1 //===--- ExprConstant.cpp - Expression Constant Evaluator -----------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file implements the Expr constant evaluator.
10 //
11 // Constant expression evaluation produces four main results:
12 //
13 // * A success/failure flag indicating whether constant folding was successful.
14 // This is the 'bool' return value used by most of the code in this file. A
15 // 'false' return value indicates that constant folding has failed, and any
16 // appropriate diagnostic has already been produced.
17 //
18 // * An evaluated result, valid only if constant folding has not failed.
19 //
20 // * A flag indicating if evaluation encountered (unevaluated) side-effects.
21 // These arise in cases such as (sideEffect(), 0) and (sideEffect() || 1),
22 // where it is possible to determine the evaluated result regardless.
23 //
24 // * A set of notes indicating why the evaluation was not a constant expression
25 // (under the C++11 / C++1y rules only, at the moment), or, if folding failed
26 // too, why the expression could not be folded.
27 //
28 // If we are checking for a potential constant expression, failure to constant
29 // fold a potential constant sub-expression will be indicated by a 'false'
30 // return value (the expression could not be folded) and no diagnostic (the
31 // expression is not necessarily non-constant).
32 //
33 //===----------------------------------------------------------------------===//
34
35 #include "ExprConstShared.h"
36 #include "Interp/Context.h"
37 #include "Interp/Frame.h"
38 #include "Interp/State.h"
39 #include "clang/AST/APValue.h"
40 #include "clang/AST/ASTContext.h"
41 #include "clang/AST/ASTDiagnostic.h"
42 #include "clang/AST/ASTLambda.h"
43 #include "clang/AST/Attr.h"
44 #include "clang/AST/CXXInheritance.h"
45 #include "clang/AST/CharUnits.h"
46 #include "clang/AST/CurrentSourceLocExprScope.h"
47 #include "clang/AST/Expr.h"
48 #include "clang/AST/OSLog.h"
49 #include "clang/AST/OptionalDiagnostic.h"
50 #include "clang/AST/RecordLayout.h"
51 #include "clang/AST/StmtVisitor.h"
52 #include "clang/AST/TypeLoc.h"
53 #include "clang/Basic/Builtins.h"
54 #include "clang/Basic/DiagnosticSema.h"
55 #include "clang/Basic/TargetInfo.h"
56 #include "llvm/ADT/APFixedPoint.h"
57 #include "llvm/ADT/SmallBitVector.h"
58 #include "llvm/ADT/StringExtras.h"
59 #include "llvm/Support/Debug.h"
60 #include "llvm/Support/SaveAndRestore.h"
61 #include "llvm/Support/TimeProfiler.h"
62 #include "llvm/Support/raw_ostream.h"
63 #include <cstring>
64 #include <functional>
65 #include <optional>
66
67 #define DEBUG_TYPE "exprconstant"
68
69 using namespace clang;
70 using llvm::APFixedPoint;
71 using llvm::APInt;
72 using llvm::APSInt;
73 using llvm::APFloat;
74 using llvm::FixedPointSemantics;
75
76 namespace {
77 struct LValue;
78 class CallStackFrame;
79 class EvalInfo;
80
81 using SourceLocExprScopeGuard =
82 CurrentSourceLocExprScope::SourceLocExprScopeGuard;
83
getType(APValue::LValueBase B)84 static QualType getType(APValue::LValueBase B) {
85 return B.getType();
86 }
87
88 /// Get an LValue path entry, which is known to not be an array index, as a
89 /// field declaration.
getAsField(APValue::LValuePathEntry E)90 static const FieldDecl *getAsField(APValue::LValuePathEntry E) {
91 return dyn_cast_or_null<FieldDecl>(E.getAsBaseOrMember().getPointer());
92 }
93 /// Get an LValue path entry, which is known to not be an array index, as a
94 /// base class declaration.
getAsBaseClass(APValue::LValuePathEntry E)95 static const CXXRecordDecl *getAsBaseClass(APValue::LValuePathEntry E) {
96 return dyn_cast_or_null<CXXRecordDecl>(E.getAsBaseOrMember().getPointer());
97 }
98 /// Determine whether this LValue path entry for a base class names a virtual
99 /// base class.
isVirtualBaseClass(APValue::LValuePathEntry E)100 static bool isVirtualBaseClass(APValue::LValuePathEntry E) {
101 return E.getAsBaseOrMember().getInt();
102 }
103
104 /// Given an expression, determine the type used to store the result of
105 /// evaluating that expression.
getStorageType(const ASTContext & Ctx,const Expr * E)106 static QualType getStorageType(const ASTContext &Ctx, const Expr *E) {
107 if (E->isPRValue())
108 return E->getType();
109 return Ctx.getLValueReferenceType(E->getType());
110 }
111
112 /// Given a CallExpr, try to get the alloc_size attribute. May return null.
getAllocSizeAttr(const CallExpr * CE)113 static const AllocSizeAttr *getAllocSizeAttr(const CallExpr *CE) {
114 if (const FunctionDecl *DirectCallee = CE->getDirectCallee())
115 return DirectCallee->getAttr<AllocSizeAttr>();
116 if (const Decl *IndirectCallee = CE->getCalleeDecl())
117 return IndirectCallee->getAttr<AllocSizeAttr>();
118 return nullptr;
119 }
120
121 /// Attempts to unwrap a CallExpr (with an alloc_size attribute) from an Expr.
122 /// This will look through a single cast.
123 ///
124 /// Returns null if we couldn't unwrap a function with alloc_size.
tryUnwrapAllocSizeCall(const Expr * E)125 static const CallExpr *tryUnwrapAllocSizeCall(const Expr *E) {
126 if (!E->getType()->isPointerType())
127 return nullptr;
128
129 E = E->IgnoreParens();
130 // If we're doing a variable assignment from e.g. malloc(N), there will
131 // probably be a cast of some kind. In exotic cases, we might also see a
132 // top-level ExprWithCleanups. Ignore them either way.
133 if (const auto *FE = dyn_cast<FullExpr>(E))
134 E = FE->getSubExpr()->IgnoreParens();
135
136 if (const auto *Cast = dyn_cast<CastExpr>(E))
137 E = Cast->getSubExpr()->IgnoreParens();
138
139 if (const auto *CE = dyn_cast<CallExpr>(E))
140 return getAllocSizeAttr(CE) ? CE : nullptr;
141 return nullptr;
142 }
143
144 /// Determines whether or not the given Base contains a call to a function
145 /// with the alloc_size attribute.
isBaseAnAllocSizeCall(APValue::LValueBase Base)146 static bool isBaseAnAllocSizeCall(APValue::LValueBase Base) {
147 const auto *E = Base.dyn_cast<const Expr *>();
148 return E && E->getType()->isPointerType() && tryUnwrapAllocSizeCall(E);
149 }
150
151 /// Determines whether the given kind of constant expression is only ever
152 /// used for name mangling. If so, it's permitted to reference things that we
153 /// can't generate code for (in particular, dllimported functions).
isForManglingOnly(ConstantExprKind Kind)154 static bool isForManglingOnly(ConstantExprKind Kind) {
155 switch (Kind) {
156 case ConstantExprKind::Normal:
157 case ConstantExprKind::ClassTemplateArgument:
158 case ConstantExprKind::ImmediateInvocation:
159 // Note that non-type template arguments of class type are emitted as
160 // template parameter objects.
161 return false;
162
163 case ConstantExprKind::NonClassTemplateArgument:
164 return true;
165 }
166 llvm_unreachable("unknown ConstantExprKind");
167 }
168
isTemplateArgument(ConstantExprKind Kind)169 static bool isTemplateArgument(ConstantExprKind Kind) {
170 switch (Kind) {
171 case ConstantExprKind::Normal:
172 case ConstantExprKind::ImmediateInvocation:
173 return false;
174
175 case ConstantExprKind::ClassTemplateArgument:
176 case ConstantExprKind::NonClassTemplateArgument:
177 return true;
178 }
179 llvm_unreachable("unknown ConstantExprKind");
180 }
181
182 /// The bound to claim that an array of unknown bound has.
183 /// The value in MostDerivedArraySize is undefined in this case. So, set it
184 /// to an arbitrary value that's likely to loudly break things if it's used.
185 static const uint64_t AssumedSizeForUnsizedArray =
186 std::numeric_limits<uint64_t>::max() / 2;
187
188 /// Determines if an LValue with the given LValueBase will have an unsized
189 /// array in its designator.
190 /// Find the path length and type of the most-derived subobject in the given
191 /// path, and find the size of the containing array, if any.
192 static unsigned
findMostDerivedSubobject(ASTContext & Ctx,APValue::LValueBase Base,ArrayRef<APValue::LValuePathEntry> Path,uint64_t & ArraySize,QualType & Type,bool & IsArray,bool & FirstEntryIsUnsizedArray)193 findMostDerivedSubobject(ASTContext &Ctx, APValue::LValueBase Base,
194 ArrayRef<APValue::LValuePathEntry> Path,
195 uint64_t &ArraySize, QualType &Type, bool &IsArray,
196 bool &FirstEntryIsUnsizedArray) {
197 // This only accepts LValueBases from APValues, and APValues don't support
198 // arrays that lack size info.
199 assert(!isBaseAnAllocSizeCall(Base) &&
200 "Unsized arrays shouldn't appear here");
201 unsigned MostDerivedLength = 0;
202 Type = getType(Base);
203
204 for (unsigned I = 0, N = Path.size(); I != N; ++I) {
205 if (Type->isArrayType()) {
206 const ArrayType *AT = Ctx.getAsArrayType(Type);
207 Type = AT->getElementType();
208 MostDerivedLength = I + 1;
209 IsArray = true;
210
211 if (auto *CAT = dyn_cast<ConstantArrayType>(AT)) {
212 ArraySize = CAT->getSize().getZExtValue();
213 } else {
214 assert(I == 0 && "unexpected unsized array designator");
215 FirstEntryIsUnsizedArray = true;
216 ArraySize = AssumedSizeForUnsizedArray;
217 }
218 } else if (Type->isAnyComplexType()) {
219 const ComplexType *CT = Type->castAs<ComplexType>();
220 Type = CT->getElementType();
221 ArraySize = 2;
222 MostDerivedLength = I + 1;
223 IsArray = true;
224 } else if (const FieldDecl *FD = getAsField(Path[I])) {
225 Type = FD->getType();
226 ArraySize = 0;
227 MostDerivedLength = I + 1;
228 IsArray = false;
229 } else {
230 // Path[I] describes a base class.
231 ArraySize = 0;
232 IsArray = false;
233 }
234 }
235 return MostDerivedLength;
236 }
237
238 /// A path from a glvalue to a subobject of that glvalue.
239 struct SubobjectDesignator {
240 /// True if the subobject was named in a manner not supported by C++11. Such
241 /// lvalues can still be folded, but they are not core constant expressions
242 /// and we cannot perform lvalue-to-rvalue conversions on them.
243 unsigned Invalid : 1;
244
245 /// Is this a pointer one past the end of an object?
246 unsigned IsOnePastTheEnd : 1;
247
248 /// Indicator of whether the first entry is an unsized array.
249 unsigned FirstEntryIsAnUnsizedArray : 1;
250
251 /// Indicator of whether the most-derived object is an array element.
252 unsigned MostDerivedIsArrayElement : 1;
253
254 /// The length of the path to the most-derived object of which this is a
255 /// subobject.
256 unsigned MostDerivedPathLength : 28;
257
258 /// The size of the array of which the most-derived object is an element.
259 /// This will always be 0 if the most-derived object is not an array
260 /// element. 0 is not an indicator of whether or not the most-derived object
261 /// is an array, however, because 0-length arrays are allowed.
262 ///
263 /// If the current array is an unsized array, the value of this is
264 /// undefined.
265 uint64_t MostDerivedArraySize;
266
267 /// The type of the most derived object referred to by this address.
268 QualType MostDerivedType;
269
270 typedef APValue::LValuePathEntry PathEntry;
271
272 /// The entries on the path from the glvalue to the designated subobject.
273 SmallVector<PathEntry, 8> Entries;
274
SubobjectDesignator__anonbf0ddd820111::SubobjectDesignator275 SubobjectDesignator() : Invalid(true) {}
276
SubobjectDesignator__anonbf0ddd820111::SubobjectDesignator277 explicit SubobjectDesignator(QualType T)
278 : Invalid(false), IsOnePastTheEnd(false),
279 FirstEntryIsAnUnsizedArray(false), MostDerivedIsArrayElement(false),
280 MostDerivedPathLength(0), MostDerivedArraySize(0),
281 MostDerivedType(T) {}
282
SubobjectDesignator__anonbf0ddd820111::SubobjectDesignator283 SubobjectDesignator(ASTContext &Ctx, const APValue &V)
284 : Invalid(!V.isLValue() || !V.hasLValuePath()), IsOnePastTheEnd(false),
285 FirstEntryIsAnUnsizedArray(false), MostDerivedIsArrayElement(false),
286 MostDerivedPathLength(0), MostDerivedArraySize(0) {
287 assert(V.isLValue() && "Non-LValue used to make an LValue designator?");
288 if (!Invalid) {
289 IsOnePastTheEnd = V.isLValueOnePastTheEnd();
290 ArrayRef<PathEntry> VEntries = V.getLValuePath();
291 Entries.insert(Entries.end(), VEntries.begin(), VEntries.end());
292 if (V.getLValueBase()) {
293 bool IsArray = false;
294 bool FirstIsUnsizedArray = false;
295 MostDerivedPathLength = findMostDerivedSubobject(
296 Ctx, V.getLValueBase(), V.getLValuePath(), MostDerivedArraySize,
297 MostDerivedType, IsArray, FirstIsUnsizedArray);
298 MostDerivedIsArrayElement = IsArray;
299 FirstEntryIsAnUnsizedArray = FirstIsUnsizedArray;
300 }
301 }
302 }
303
truncate__anonbf0ddd820111::SubobjectDesignator304 void truncate(ASTContext &Ctx, APValue::LValueBase Base,
305 unsigned NewLength) {
306 if (Invalid)
307 return;
308
309 assert(Base && "cannot truncate path for null pointer");
310 assert(NewLength <= Entries.size() && "not a truncation");
311
312 if (NewLength == Entries.size())
313 return;
314 Entries.resize(NewLength);
315
316 bool IsArray = false;
317 bool FirstIsUnsizedArray = false;
318 MostDerivedPathLength = findMostDerivedSubobject(
319 Ctx, Base, Entries, MostDerivedArraySize, MostDerivedType, IsArray,
320 FirstIsUnsizedArray);
321 MostDerivedIsArrayElement = IsArray;
322 FirstEntryIsAnUnsizedArray = FirstIsUnsizedArray;
323 }
324
setInvalid__anonbf0ddd820111::SubobjectDesignator325 void setInvalid() {
326 Invalid = true;
327 Entries.clear();
328 }
329
330 /// Determine whether the most derived subobject is an array without a
331 /// known bound.
isMostDerivedAnUnsizedArray__anonbf0ddd820111::SubobjectDesignator332 bool isMostDerivedAnUnsizedArray() const {
333 assert(!Invalid && "Calling this makes no sense on invalid designators");
334 return Entries.size() == 1 && FirstEntryIsAnUnsizedArray;
335 }
336
337 /// Determine what the most derived array's size is. Results in an assertion
338 /// failure if the most derived array lacks a size.
getMostDerivedArraySize__anonbf0ddd820111::SubobjectDesignator339 uint64_t getMostDerivedArraySize() const {
340 assert(!isMostDerivedAnUnsizedArray() && "Unsized array has no size");
341 return MostDerivedArraySize;
342 }
343
344 /// Determine whether this is a one-past-the-end pointer.
isOnePastTheEnd__anonbf0ddd820111::SubobjectDesignator345 bool isOnePastTheEnd() const {
346 assert(!Invalid);
347 if (IsOnePastTheEnd)
348 return true;
349 if (!isMostDerivedAnUnsizedArray() && MostDerivedIsArrayElement &&
350 Entries[MostDerivedPathLength - 1].getAsArrayIndex() ==
351 MostDerivedArraySize)
352 return true;
353 return false;
354 }
355
356 /// Get the range of valid index adjustments in the form
357 /// {maximum value that can be subtracted from this pointer,
358 /// maximum value that can be added to this pointer}
validIndexAdjustments__anonbf0ddd820111::SubobjectDesignator359 std::pair<uint64_t, uint64_t> validIndexAdjustments() {
360 if (Invalid || isMostDerivedAnUnsizedArray())
361 return {0, 0};
362
363 // [expr.add]p4: For the purposes of these operators, a pointer to a
364 // nonarray object behaves the same as a pointer to the first element of
365 // an array of length one with the type of the object as its element type.
366 bool IsArray = MostDerivedPathLength == Entries.size() &&
367 MostDerivedIsArrayElement;
368 uint64_t ArrayIndex = IsArray ? Entries.back().getAsArrayIndex()
369 : (uint64_t)IsOnePastTheEnd;
370 uint64_t ArraySize =
371 IsArray ? getMostDerivedArraySize() : (uint64_t)1;
372 return {ArrayIndex, ArraySize - ArrayIndex};
373 }
374
375 /// Check that this refers to a valid subobject.
isValidSubobject__anonbf0ddd820111::SubobjectDesignator376 bool isValidSubobject() const {
377 if (Invalid)
378 return false;
379 return !isOnePastTheEnd();
380 }
381 /// Check that this refers to a valid subobject, and if not, produce a
382 /// relevant diagnostic and set the designator as invalid.
383 bool checkSubobject(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK);
384
385 /// Get the type of the designated object.
getType__anonbf0ddd820111::SubobjectDesignator386 QualType getType(ASTContext &Ctx) const {
387 assert(!Invalid && "invalid designator has no subobject type");
388 return MostDerivedPathLength == Entries.size()
389 ? MostDerivedType
390 : Ctx.getRecordType(getAsBaseClass(Entries.back()));
391 }
392
393 /// Update this designator to refer to the first element within this array.
addArrayUnchecked__anonbf0ddd820111::SubobjectDesignator394 void addArrayUnchecked(const ConstantArrayType *CAT) {
395 Entries.push_back(PathEntry::ArrayIndex(0));
396
397 // This is a most-derived object.
398 MostDerivedType = CAT->getElementType();
399 MostDerivedIsArrayElement = true;
400 MostDerivedArraySize = CAT->getSize().getZExtValue();
401 MostDerivedPathLength = Entries.size();
402 }
403 /// Update this designator to refer to the first element within the array of
404 /// elements of type T. This is an array of unknown size.
addUnsizedArrayUnchecked__anonbf0ddd820111::SubobjectDesignator405 void addUnsizedArrayUnchecked(QualType ElemTy) {
406 Entries.push_back(PathEntry::ArrayIndex(0));
407
408 MostDerivedType = ElemTy;
409 MostDerivedIsArrayElement = true;
410 // The value in MostDerivedArraySize is undefined in this case. So, set it
411 // to an arbitrary value that's likely to loudly break things if it's
412 // used.
413 MostDerivedArraySize = AssumedSizeForUnsizedArray;
414 MostDerivedPathLength = Entries.size();
415 }
416 /// Update this designator to refer to the given base or member of this
417 /// object.
addDeclUnchecked__anonbf0ddd820111::SubobjectDesignator418 void addDeclUnchecked(const Decl *D, bool Virtual = false) {
419 Entries.push_back(APValue::BaseOrMemberType(D, Virtual));
420
421 // If this isn't a base class, it's a new most-derived object.
422 if (const FieldDecl *FD = dyn_cast<FieldDecl>(D)) {
423 MostDerivedType = FD->getType();
424 MostDerivedIsArrayElement = false;
425 MostDerivedArraySize = 0;
426 MostDerivedPathLength = Entries.size();
427 }
428 }
429 /// Update this designator to refer to the given complex component.
addComplexUnchecked__anonbf0ddd820111::SubobjectDesignator430 void addComplexUnchecked(QualType EltTy, bool Imag) {
431 Entries.push_back(PathEntry::ArrayIndex(Imag));
432
433 // This is technically a most-derived object, though in practice this
434 // is unlikely to matter.
435 MostDerivedType = EltTy;
436 MostDerivedIsArrayElement = true;
437 MostDerivedArraySize = 2;
438 MostDerivedPathLength = Entries.size();
439 }
440 void diagnoseUnsizedArrayPointerArithmetic(EvalInfo &Info, const Expr *E);
441 void diagnosePointerArithmetic(EvalInfo &Info, const Expr *E,
442 const APSInt &N);
443 /// Add N to the address of this subobject.
adjustIndex__anonbf0ddd820111::SubobjectDesignator444 void adjustIndex(EvalInfo &Info, const Expr *E, APSInt N) {
445 if (Invalid || !N) return;
446 uint64_t TruncatedN = N.extOrTrunc(64).getZExtValue();
447 if (isMostDerivedAnUnsizedArray()) {
448 diagnoseUnsizedArrayPointerArithmetic(Info, E);
449 // Can't verify -- trust that the user is doing the right thing (or if
450 // not, trust that the caller will catch the bad behavior).
451 // FIXME: Should we reject if this overflows, at least?
452 Entries.back() = PathEntry::ArrayIndex(
453 Entries.back().getAsArrayIndex() + TruncatedN);
454 return;
455 }
456
457 // [expr.add]p4: For the purposes of these operators, a pointer to a
458 // nonarray object behaves the same as a pointer to the first element of
459 // an array of length one with the type of the object as its element type.
460 bool IsArray = MostDerivedPathLength == Entries.size() &&
461 MostDerivedIsArrayElement;
462 uint64_t ArrayIndex = IsArray ? Entries.back().getAsArrayIndex()
463 : (uint64_t)IsOnePastTheEnd;
464 uint64_t ArraySize =
465 IsArray ? getMostDerivedArraySize() : (uint64_t)1;
466
467 if (N < -(int64_t)ArrayIndex || N > ArraySize - ArrayIndex) {
468 // Calculate the actual index in a wide enough type, so we can include
469 // it in the note.
470 N = N.extend(std::max<unsigned>(N.getBitWidth() + 1, 65));
471 (llvm::APInt&)N += ArrayIndex;
472 assert(N.ugt(ArraySize) && "bounds check failed for in-bounds index");
473 diagnosePointerArithmetic(Info, E, N);
474 setInvalid();
475 return;
476 }
477
478 ArrayIndex += TruncatedN;
479 assert(ArrayIndex <= ArraySize &&
480 "bounds check succeeded for out-of-bounds index");
481
482 if (IsArray)
483 Entries.back() = PathEntry::ArrayIndex(ArrayIndex);
484 else
485 IsOnePastTheEnd = (ArrayIndex != 0);
486 }
487 };
488
489 /// A scope at the end of which an object can need to be destroyed.
490 enum class ScopeKind {
491 Block,
492 FullExpression,
493 Call
494 };
495
496 /// A reference to a particular call and its arguments.
497 struct CallRef {
CallRef__anonbf0ddd820111::CallRef498 CallRef() : OrigCallee(), CallIndex(0), Version() {}
CallRef__anonbf0ddd820111::CallRef499 CallRef(const FunctionDecl *Callee, unsigned CallIndex, unsigned Version)
500 : OrigCallee(Callee), CallIndex(CallIndex), Version(Version) {}
501
operator bool__anonbf0ddd820111::CallRef502 explicit operator bool() const { return OrigCallee; }
503
504 /// Get the parameter that the caller initialized, corresponding to the
505 /// given parameter in the callee.
getOrigParam__anonbf0ddd820111::CallRef506 const ParmVarDecl *getOrigParam(const ParmVarDecl *PVD) const {
507 return OrigCallee ? OrigCallee->getParamDecl(PVD->getFunctionScopeIndex())
508 : PVD;
509 }
510
511 /// The callee at the point where the arguments were evaluated. This might
512 /// be different from the actual callee (a different redeclaration, or a
513 /// virtual override), but this function's parameters are the ones that
514 /// appear in the parameter map.
515 const FunctionDecl *OrigCallee;
516 /// The call index of the frame that holds the argument values.
517 unsigned CallIndex;
518 /// The version of the parameters corresponding to this call.
519 unsigned Version;
520 };
521
522 /// A stack frame in the constexpr call stack.
523 class CallStackFrame : public interp::Frame {
524 public:
525 EvalInfo &Info;
526
527 /// Parent - The caller of this stack frame.
528 CallStackFrame *Caller;
529
530 /// Callee - The function which was called.
531 const FunctionDecl *Callee;
532
533 /// This - The binding for the this pointer in this call, if any.
534 const LValue *This;
535
536 /// CallExpr - The syntactical structure of member function calls
537 const Expr *CallExpr;
538
539 /// Information on how to find the arguments to this call. Our arguments
540 /// are stored in our parent's CallStackFrame, using the ParmVarDecl* as a
541 /// key and this value as the version.
542 CallRef Arguments;
543
544 /// Source location information about the default argument or default
545 /// initializer expression we're evaluating, if any.
546 CurrentSourceLocExprScope CurSourceLocExprScope;
547
548 // Note that we intentionally use std::map here so that references to
549 // values are stable.
550 typedef std::pair<const void *, unsigned> MapKeyTy;
551 typedef std::map<MapKeyTy, APValue> MapTy;
552 /// Temporaries - Temporary lvalues materialized within this stack frame.
553 MapTy Temporaries;
554
555 /// CallRange - The source range of the call expression for this call.
556 SourceRange CallRange;
557
558 /// Index - The call index of this call.
559 unsigned Index;
560
561 /// The stack of integers for tracking version numbers for temporaries.
562 SmallVector<unsigned, 2> TempVersionStack = {1};
563 unsigned CurTempVersion = TempVersionStack.back();
564
getTempVersion() const565 unsigned getTempVersion() const { return TempVersionStack.back(); }
566
pushTempVersion()567 void pushTempVersion() {
568 TempVersionStack.push_back(++CurTempVersion);
569 }
570
popTempVersion()571 void popTempVersion() {
572 TempVersionStack.pop_back();
573 }
574
createCall(const FunctionDecl * Callee)575 CallRef createCall(const FunctionDecl *Callee) {
576 return {Callee, Index, ++CurTempVersion};
577 }
578
579 // FIXME: Adding this to every 'CallStackFrame' may have a nontrivial impact
580 // on the overall stack usage of deeply-recursing constexpr evaluations.
581 // (We should cache this map rather than recomputing it repeatedly.)
582 // But let's try this and see how it goes; we can look into caching the map
583 // as a later change.
584
585 /// LambdaCaptureFields - Mapping from captured variables/this to
586 /// corresponding data members in the closure class.
587 llvm::DenseMap<const ValueDecl *, FieldDecl *> LambdaCaptureFields;
588 FieldDecl *LambdaThisCaptureField = nullptr;
589
590 CallStackFrame(EvalInfo &Info, SourceRange CallRange,
591 const FunctionDecl *Callee, const LValue *This,
592 const Expr *CallExpr, CallRef Arguments);
593 ~CallStackFrame();
594
595 // Return the temporary for Key whose version number is Version.
getTemporary(const void * Key,unsigned Version)596 APValue *getTemporary(const void *Key, unsigned Version) {
597 MapKeyTy KV(Key, Version);
598 auto LB = Temporaries.lower_bound(KV);
599 if (LB != Temporaries.end() && LB->first == KV)
600 return &LB->second;
601 return nullptr;
602 }
603
604 // Return the current temporary for Key in the map.
getCurrentTemporary(const void * Key)605 APValue *getCurrentTemporary(const void *Key) {
606 auto UB = Temporaries.upper_bound(MapKeyTy(Key, UINT_MAX));
607 if (UB != Temporaries.begin() && std::prev(UB)->first.first == Key)
608 return &std::prev(UB)->second;
609 return nullptr;
610 }
611
612 // Return the version number of the current temporary for Key.
getCurrentTemporaryVersion(const void * Key) const613 unsigned getCurrentTemporaryVersion(const void *Key) const {
614 auto UB = Temporaries.upper_bound(MapKeyTy(Key, UINT_MAX));
615 if (UB != Temporaries.begin() && std::prev(UB)->first.first == Key)
616 return std::prev(UB)->first.second;
617 return 0;
618 }
619
620 /// Allocate storage for an object of type T in this stack frame.
621 /// Populates LV with a handle to the created object. Key identifies
622 /// the temporary within the stack frame, and must not be reused without
623 /// bumping the temporary version number.
624 template<typename KeyT>
625 APValue &createTemporary(const KeyT *Key, QualType T,
626 ScopeKind Scope, LValue &LV);
627
628 /// Allocate storage for a parameter of a function call made in this frame.
629 APValue &createParam(CallRef Args, const ParmVarDecl *PVD, LValue &LV);
630
631 void describe(llvm::raw_ostream &OS) const override;
632
getCaller() const633 Frame *getCaller() const override { return Caller; }
getCallRange() const634 SourceRange getCallRange() const override { return CallRange; }
getCallee() const635 const FunctionDecl *getCallee() const override { return Callee; }
636
isStdFunction() const637 bool isStdFunction() const {
638 for (const DeclContext *DC = Callee; DC; DC = DC->getParent())
639 if (DC->isStdNamespace())
640 return true;
641 return false;
642 }
643
644 /// Whether we're in a context where [[msvc::constexpr]] evaluation is
645 /// permitted. See MSConstexprDocs for description of permitted contexts.
646 bool CanEvalMSConstexpr = false;
647
648 private:
649 APValue &createLocal(APValue::LValueBase Base, const void *Key, QualType T,
650 ScopeKind Scope);
651 };
652
653 /// Temporarily override 'this'.
654 class ThisOverrideRAII {
655 public:
ThisOverrideRAII(CallStackFrame & Frame,const LValue * NewThis,bool Enable)656 ThisOverrideRAII(CallStackFrame &Frame, const LValue *NewThis, bool Enable)
657 : Frame(Frame), OldThis(Frame.This) {
658 if (Enable)
659 Frame.This = NewThis;
660 }
~ThisOverrideRAII()661 ~ThisOverrideRAII() {
662 Frame.This = OldThis;
663 }
664 private:
665 CallStackFrame &Frame;
666 const LValue *OldThis;
667 };
668
669 // A shorthand time trace scope struct, prints source range, for example
670 // {"name":"EvaluateAsRValue","args":{"detail":"<test.cc:8:21, col:25>"}}}
671 class ExprTimeTraceScope {
672 public:
ExprTimeTraceScope(const Expr * E,const ASTContext & Ctx,StringRef Name)673 ExprTimeTraceScope(const Expr *E, const ASTContext &Ctx, StringRef Name)
674 : TimeScope(Name, [E, &Ctx] {
675 return E->getSourceRange().printToString(Ctx.getSourceManager());
676 }) {}
677
678 private:
679 llvm::TimeTraceScope TimeScope;
680 };
681
682 /// RAII object used to change the current ability of
683 /// [[msvc::constexpr]] evaulation.
684 struct MSConstexprContextRAII {
685 CallStackFrame &Frame;
686 bool OldValue;
MSConstexprContextRAII__anonbf0ddd820111::MSConstexprContextRAII687 explicit MSConstexprContextRAII(CallStackFrame &Frame, bool Value)
688 : Frame(Frame), OldValue(Frame.CanEvalMSConstexpr) {
689 Frame.CanEvalMSConstexpr = Value;
690 }
691
~MSConstexprContextRAII__anonbf0ddd820111::MSConstexprContextRAII692 ~MSConstexprContextRAII() { Frame.CanEvalMSConstexpr = OldValue; }
693 };
694 }
695
696 static bool HandleDestruction(EvalInfo &Info, const Expr *E,
697 const LValue &This, QualType ThisType);
698 static bool HandleDestruction(EvalInfo &Info, SourceLocation Loc,
699 APValue::LValueBase LVBase, APValue &Value,
700 QualType T);
701
702 namespace {
703 /// A cleanup, and a flag indicating whether it is lifetime-extended.
704 class Cleanup {
705 llvm::PointerIntPair<APValue*, 2, ScopeKind> Value;
706 APValue::LValueBase Base;
707 QualType T;
708
709 public:
Cleanup(APValue * Val,APValue::LValueBase Base,QualType T,ScopeKind Scope)710 Cleanup(APValue *Val, APValue::LValueBase Base, QualType T,
711 ScopeKind Scope)
712 : Value(Val, Scope), Base(Base), T(T) {}
713
714 /// Determine whether this cleanup should be performed at the end of the
715 /// given kind of scope.
isDestroyedAtEndOf(ScopeKind K) const716 bool isDestroyedAtEndOf(ScopeKind K) const {
717 return (int)Value.getInt() >= (int)K;
718 }
endLifetime(EvalInfo & Info,bool RunDestructors)719 bool endLifetime(EvalInfo &Info, bool RunDestructors) {
720 if (RunDestructors) {
721 SourceLocation Loc;
722 if (const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>())
723 Loc = VD->getLocation();
724 else if (const Expr *E = Base.dyn_cast<const Expr*>())
725 Loc = E->getExprLoc();
726 return HandleDestruction(Info, Loc, Base, *Value.getPointer(), T);
727 }
728 *Value.getPointer() = APValue();
729 return true;
730 }
731
hasSideEffect()732 bool hasSideEffect() {
733 return T.isDestructedType();
734 }
735 };
736
737 /// A reference to an object whose construction we are currently evaluating.
738 struct ObjectUnderConstruction {
739 APValue::LValueBase Base;
740 ArrayRef<APValue::LValuePathEntry> Path;
operator ==(const ObjectUnderConstruction & LHS,const ObjectUnderConstruction & RHS)741 friend bool operator==(const ObjectUnderConstruction &LHS,
742 const ObjectUnderConstruction &RHS) {
743 return LHS.Base == RHS.Base && LHS.Path == RHS.Path;
744 }
hash_value(const ObjectUnderConstruction & Obj)745 friend llvm::hash_code hash_value(const ObjectUnderConstruction &Obj) {
746 return llvm::hash_combine(Obj.Base, Obj.Path);
747 }
748 };
749 enum class ConstructionPhase {
750 None,
751 Bases,
752 AfterBases,
753 AfterFields,
754 Destroying,
755 DestroyingBases
756 };
757 }
758
759 namespace llvm {
760 template<> struct DenseMapInfo<ObjectUnderConstruction> {
761 using Base = DenseMapInfo<APValue::LValueBase>;
getEmptyKeyllvm::DenseMapInfo762 static ObjectUnderConstruction getEmptyKey() {
763 return {Base::getEmptyKey(), {}}; }
getTombstoneKeyllvm::DenseMapInfo764 static ObjectUnderConstruction getTombstoneKey() {
765 return {Base::getTombstoneKey(), {}};
766 }
getHashValuellvm::DenseMapInfo767 static unsigned getHashValue(const ObjectUnderConstruction &Object) {
768 return hash_value(Object);
769 }
isEqualllvm::DenseMapInfo770 static bool isEqual(const ObjectUnderConstruction &LHS,
771 const ObjectUnderConstruction &RHS) {
772 return LHS == RHS;
773 }
774 };
775 }
776
777 namespace {
778 /// A dynamically-allocated heap object.
779 struct DynAlloc {
780 /// The value of this heap-allocated object.
781 APValue Value;
782 /// The allocating expression; used for diagnostics. Either a CXXNewExpr
783 /// or a CallExpr (the latter is for direct calls to operator new inside
784 /// std::allocator<T>::allocate).
785 const Expr *AllocExpr = nullptr;
786
787 enum Kind {
788 New,
789 ArrayNew,
790 StdAllocator
791 };
792
793 /// Get the kind of the allocation. This must match between allocation
794 /// and deallocation.
getKind__anonbf0ddd820411::DynAlloc795 Kind getKind() const {
796 if (auto *NE = dyn_cast<CXXNewExpr>(AllocExpr))
797 return NE->isArray() ? ArrayNew : New;
798 assert(isa<CallExpr>(AllocExpr));
799 return StdAllocator;
800 }
801 };
802
803 struct DynAllocOrder {
operator ()__anonbf0ddd820411::DynAllocOrder804 bool operator()(DynamicAllocLValue L, DynamicAllocLValue R) const {
805 return L.getIndex() < R.getIndex();
806 }
807 };
808
809 /// EvalInfo - This is a private struct used by the evaluator to capture
810 /// information about a subexpression as it is folded. It retains information
811 /// about the AST context, but also maintains information about the folded
812 /// expression.
813 ///
814 /// If an expression could be evaluated, it is still possible it is not a C
815 /// "integer constant expression" or constant expression. If not, this struct
816 /// captures information about how and why not.
817 ///
818 /// One bit of information passed *into* the request for constant folding
819 /// indicates whether the subexpression is "evaluated" or not according to C
820 /// rules. For example, the RHS of (0 && foo()) is not evaluated. We can
821 /// evaluate the expression regardless of what the RHS is, but C only allows
822 /// certain things in certain situations.
823 class EvalInfo : public interp::State {
824 public:
825 ASTContext &Ctx;
826
827 /// EvalStatus - Contains information about the evaluation.
828 Expr::EvalStatus &EvalStatus;
829
830 /// CurrentCall - The top of the constexpr call stack.
831 CallStackFrame *CurrentCall;
832
833 /// CallStackDepth - The number of calls in the call stack right now.
834 unsigned CallStackDepth;
835
836 /// NextCallIndex - The next call index to assign.
837 unsigned NextCallIndex;
838
839 /// StepsLeft - The remaining number of evaluation steps we're permitted
840 /// to perform. This is essentially a limit for the number of statements
841 /// we will evaluate.
842 unsigned StepsLeft;
843
844 /// Enable the experimental new constant interpreter. If an expression is
845 /// not supported by the interpreter, an error is triggered.
846 bool EnableNewConstInterp;
847
848 /// BottomFrame - The frame in which evaluation started. This must be
849 /// initialized after CurrentCall and CallStackDepth.
850 CallStackFrame BottomFrame;
851
852 /// A stack of values whose lifetimes end at the end of some surrounding
853 /// evaluation frame.
854 llvm::SmallVector<Cleanup, 16> CleanupStack;
855
856 /// EvaluatingDecl - This is the declaration whose initializer is being
857 /// evaluated, if any.
858 APValue::LValueBase EvaluatingDecl;
859
860 enum class EvaluatingDeclKind {
861 None,
862 /// We're evaluating the construction of EvaluatingDecl.
863 Ctor,
864 /// We're evaluating the destruction of EvaluatingDecl.
865 Dtor,
866 };
867 EvaluatingDeclKind IsEvaluatingDecl = EvaluatingDeclKind::None;
868
869 /// EvaluatingDeclValue - This is the value being constructed for the
870 /// declaration whose initializer is being evaluated, if any.
871 APValue *EvaluatingDeclValue;
872
873 /// Set of objects that are currently being constructed.
874 llvm::DenseMap<ObjectUnderConstruction, ConstructionPhase>
875 ObjectsUnderConstruction;
876
877 /// Current heap allocations, along with the location where each was
878 /// allocated. We use std::map here because we need stable addresses
879 /// for the stored APValues.
880 std::map<DynamicAllocLValue, DynAlloc, DynAllocOrder> HeapAllocs;
881
882 /// The number of heap allocations performed so far in this evaluation.
883 unsigned NumHeapAllocs = 0;
884
885 struct EvaluatingConstructorRAII {
886 EvalInfo &EI;
887 ObjectUnderConstruction Object;
888 bool DidInsert;
EvaluatingConstructorRAII__anonbf0ddd820411::EvalInfo::EvaluatingConstructorRAII889 EvaluatingConstructorRAII(EvalInfo &EI, ObjectUnderConstruction Object,
890 bool HasBases)
891 : EI(EI), Object(Object) {
892 DidInsert =
893 EI.ObjectsUnderConstruction
894 .insert({Object, HasBases ? ConstructionPhase::Bases
895 : ConstructionPhase::AfterBases})
896 .second;
897 }
finishedConstructingBases__anonbf0ddd820411::EvalInfo::EvaluatingConstructorRAII898 void finishedConstructingBases() {
899 EI.ObjectsUnderConstruction[Object] = ConstructionPhase::AfterBases;
900 }
finishedConstructingFields__anonbf0ddd820411::EvalInfo::EvaluatingConstructorRAII901 void finishedConstructingFields() {
902 EI.ObjectsUnderConstruction[Object] = ConstructionPhase::AfterFields;
903 }
~EvaluatingConstructorRAII__anonbf0ddd820411::EvalInfo::EvaluatingConstructorRAII904 ~EvaluatingConstructorRAII() {
905 if (DidInsert) EI.ObjectsUnderConstruction.erase(Object);
906 }
907 };
908
909 struct EvaluatingDestructorRAII {
910 EvalInfo &EI;
911 ObjectUnderConstruction Object;
912 bool DidInsert;
EvaluatingDestructorRAII__anonbf0ddd820411::EvalInfo::EvaluatingDestructorRAII913 EvaluatingDestructorRAII(EvalInfo &EI, ObjectUnderConstruction Object)
914 : EI(EI), Object(Object) {
915 DidInsert = EI.ObjectsUnderConstruction
916 .insert({Object, ConstructionPhase::Destroying})
917 .second;
918 }
startedDestroyingBases__anonbf0ddd820411::EvalInfo::EvaluatingDestructorRAII919 void startedDestroyingBases() {
920 EI.ObjectsUnderConstruction[Object] =
921 ConstructionPhase::DestroyingBases;
922 }
~EvaluatingDestructorRAII__anonbf0ddd820411::EvalInfo::EvaluatingDestructorRAII923 ~EvaluatingDestructorRAII() {
924 if (DidInsert)
925 EI.ObjectsUnderConstruction.erase(Object);
926 }
927 };
928
929 ConstructionPhase
isEvaluatingCtorDtor(APValue::LValueBase Base,ArrayRef<APValue::LValuePathEntry> Path)930 isEvaluatingCtorDtor(APValue::LValueBase Base,
931 ArrayRef<APValue::LValuePathEntry> Path) {
932 return ObjectsUnderConstruction.lookup({Base, Path});
933 }
934
935 /// If we're currently speculatively evaluating, the outermost call stack
936 /// depth at which we can mutate state, otherwise 0.
937 unsigned SpeculativeEvaluationDepth = 0;
938
939 /// The current array initialization index, if we're performing array
940 /// initialization.
941 uint64_t ArrayInitIndex = -1;
942
943 /// HasActiveDiagnostic - Was the previous diagnostic stored? If so, further
944 /// notes attached to it will also be stored, otherwise they will not be.
945 bool HasActiveDiagnostic;
946
947 /// Have we emitted a diagnostic explaining why we couldn't constant
948 /// fold (not just why it's not strictly a constant expression)?
949 bool HasFoldFailureDiagnostic;
950
951 /// Whether we're checking that an expression is a potential constant
952 /// expression. If so, do not fail on constructs that could become constant
953 /// later on (such as a use of an undefined global).
954 bool CheckingPotentialConstantExpression = false;
955
956 /// Whether we're checking for an expression that has undefined behavior.
957 /// If so, we will produce warnings if we encounter an operation that is
958 /// always undefined.
959 ///
960 /// Note that we still need to evaluate the expression normally when this
961 /// is set; this is used when evaluating ICEs in C.
962 bool CheckingForUndefinedBehavior = false;
963
964 enum EvaluationMode {
965 /// Evaluate as a constant expression. Stop if we find that the expression
966 /// is not a constant expression.
967 EM_ConstantExpression,
968
969 /// Evaluate as a constant expression. Stop if we find that the expression
970 /// is not a constant expression. Some expressions can be retried in the
971 /// optimizer if we don't constant fold them here, but in an unevaluated
972 /// context we try to fold them immediately since the optimizer never
973 /// gets a chance to look at it.
974 EM_ConstantExpressionUnevaluated,
975
976 /// Fold the expression to a constant. Stop if we hit a side-effect that
977 /// we can't model.
978 EM_ConstantFold,
979
980 /// Evaluate in any way we know how. Don't worry about side-effects that
981 /// can't be modeled.
982 EM_IgnoreSideEffects,
983 } EvalMode;
984
985 /// Are we checking whether the expression is a potential constant
986 /// expression?
checkingPotentialConstantExpression() const987 bool checkingPotentialConstantExpression() const override {
988 return CheckingPotentialConstantExpression;
989 }
990
991 /// Are we checking an expression for overflow?
992 // FIXME: We should check for any kind of undefined or suspicious behavior
993 // in such constructs, not just overflow.
checkingForUndefinedBehavior() const994 bool checkingForUndefinedBehavior() const override {
995 return CheckingForUndefinedBehavior;
996 }
997
EvalInfo(const ASTContext & C,Expr::EvalStatus & S,EvaluationMode Mode)998 EvalInfo(const ASTContext &C, Expr::EvalStatus &S, EvaluationMode Mode)
999 : Ctx(const_cast<ASTContext &>(C)), EvalStatus(S), CurrentCall(nullptr),
1000 CallStackDepth(0), NextCallIndex(1),
1001 StepsLeft(C.getLangOpts().ConstexprStepLimit),
1002 EnableNewConstInterp(C.getLangOpts().EnableNewConstInterp),
1003 BottomFrame(*this, SourceLocation(), /*Callee=*/nullptr,
1004 /*This=*/nullptr,
1005 /*CallExpr=*/nullptr, CallRef()),
1006 EvaluatingDecl((const ValueDecl *)nullptr),
1007 EvaluatingDeclValue(nullptr), HasActiveDiagnostic(false),
1008 HasFoldFailureDiagnostic(false), EvalMode(Mode) {}
1009
~EvalInfo()1010 ~EvalInfo() {
1011 discardCleanups();
1012 }
1013
getCtx() const1014 ASTContext &getCtx() const override { return Ctx; }
1015
setEvaluatingDecl(APValue::LValueBase Base,APValue & Value,EvaluatingDeclKind EDK=EvaluatingDeclKind::Ctor)1016 void setEvaluatingDecl(APValue::LValueBase Base, APValue &Value,
1017 EvaluatingDeclKind EDK = EvaluatingDeclKind::Ctor) {
1018 EvaluatingDecl = Base;
1019 IsEvaluatingDecl = EDK;
1020 EvaluatingDeclValue = &Value;
1021 }
1022
CheckCallLimit(SourceLocation Loc)1023 bool CheckCallLimit(SourceLocation Loc) {
1024 // Don't perform any constexpr calls (other than the call we're checking)
1025 // when checking a potential constant expression.
1026 if (checkingPotentialConstantExpression() && CallStackDepth > 1)
1027 return false;
1028 if (NextCallIndex == 0) {
1029 // NextCallIndex has wrapped around.
1030 FFDiag(Loc, diag::note_constexpr_call_limit_exceeded);
1031 return false;
1032 }
1033 if (CallStackDepth <= getLangOpts().ConstexprCallDepth)
1034 return true;
1035 FFDiag(Loc, diag::note_constexpr_depth_limit_exceeded)
1036 << getLangOpts().ConstexprCallDepth;
1037 return false;
1038 }
1039
CheckArraySize(SourceLocation Loc,unsigned BitWidth,uint64_t ElemCount,bool Diag)1040 bool CheckArraySize(SourceLocation Loc, unsigned BitWidth,
1041 uint64_t ElemCount, bool Diag) {
1042 // FIXME: GH63562
1043 // APValue stores array extents as unsigned,
1044 // so anything that is greater that unsigned would overflow when
1045 // constructing the array, we catch this here.
1046 if (BitWidth > ConstantArrayType::getMaxSizeBits(Ctx) ||
1047 ElemCount > uint64_t(std::numeric_limits<unsigned>::max())) {
1048 if (Diag)
1049 FFDiag(Loc, diag::note_constexpr_new_too_large) << ElemCount;
1050 return false;
1051 }
1052
1053 // FIXME: GH63562
1054 // Arrays allocate an APValue per element.
1055 // We use the number of constexpr steps as a proxy for the maximum size
1056 // of arrays to avoid exhausting the system resources, as initialization
1057 // of each element is likely to take some number of steps anyway.
1058 uint64_t Limit = Ctx.getLangOpts().ConstexprStepLimit;
1059 if (ElemCount > Limit) {
1060 if (Diag)
1061 FFDiag(Loc, diag::note_constexpr_new_exceeds_limits)
1062 << ElemCount << Limit;
1063 return false;
1064 }
1065 return true;
1066 }
1067
1068 std::pair<CallStackFrame *, unsigned>
getCallFrameAndDepth(unsigned CallIndex)1069 getCallFrameAndDepth(unsigned CallIndex) {
1070 assert(CallIndex && "no call index in getCallFrameAndDepth");
1071 // We will eventually hit BottomFrame, which has Index 1, so Frame can't
1072 // be null in this loop.
1073 unsigned Depth = CallStackDepth;
1074 CallStackFrame *Frame = CurrentCall;
1075 while (Frame->Index > CallIndex) {
1076 Frame = Frame->Caller;
1077 --Depth;
1078 }
1079 if (Frame->Index == CallIndex)
1080 return {Frame, Depth};
1081 return {nullptr, 0};
1082 }
1083
nextStep(const Stmt * S)1084 bool nextStep(const Stmt *S) {
1085 if (!StepsLeft) {
1086 FFDiag(S->getBeginLoc(), diag::note_constexpr_step_limit_exceeded);
1087 return false;
1088 }
1089 --StepsLeft;
1090 return true;
1091 }
1092
1093 APValue *createHeapAlloc(const Expr *E, QualType T, LValue &LV);
1094
lookupDynamicAlloc(DynamicAllocLValue DA)1095 std::optional<DynAlloc *> lookupDynamicAlloc(DynamicAllocLValue DA) {
1096 std::optional<DynAlloc *> Result;
1097 auto It = HeapAllocs.find(DA);
1098 if (It != HeapAllocs.end())
1099 Result = &It->second;
1100 return Result;
1101 }
1102
1103 /// Get the allocated storage for the given parameter of the given call.
getParamSlot(CallRef Call,const ParmVarDecl * PVD)1104 APValue *getParamSlot(CallRef Call, const ParmVarDecl *PVD) {
1105 CallStackFrame *Frame = getCallFrameAndDepth(Call.CallIndex).first;
1106 return Frame ? Frame->getTemporary(Call.getOrigParam(PVD), Call.Version)
1107 : nullptr;
1108 }
1109
1110 /// Information about a stack frame for std::allocator<T>::[de]allocate.
1111 struct StdAllocatorCaller {
1112 unsigned FrameIndex;
1113 QualType ElemType;
operator bool__anonbf0ddd820411::EvalInfo::StdAllocatorCaller1114 explicit operator bool() const { return FrameIndex != 0; };
1115 };
1116
getStdAllocatorCaller(StringRef FnName) const1117 StdAllocatorCaller getStdAllocatorCaller(StringRef FnName) const {
1118 for (const CallStackFrame *Call = CurrentCall; Call != &BottomFrame;
1119 Call = Call->Caller) {
1120 const auto *MD = dyn_cast_or_null<CXXMethodDecl>(Call->Callee);
1121 if (!MD)
1122 continue;
1123 const IdentifierInfo *FnII = MD->getIdentifier();
1124 if (!FnII || !FnII->isStr(FnName))
1125 continue;
1126
1127 const auto *CTSD =
1128 dyn_cast<ClassTemplateSpecializationDecl>(MD->getParent());
1129 if (!CTSD)
1130 continue;
1131
1132 const IdentifierInfo *ClassII = CTSD->getIdentifier();
1133 const TemplateArgumentList &TAL = CTSD->getTemplateArgs();
1134 if (CTSD->isInStdNamespace() && ClassII &&
1135 ClassII->isStr("allocator") && TAL.size() >= 1 &&
1136 TAL[0].getKind() == TemplateArgument::Type)
1137 return {Call->Index, TAL[0].getAsType()};
1138 }
1139
1140 return {};
1141 }
1142
performLifetimeExtension()1143 void performLifetimeExtension() {
1144 // Disable the cleanups for lifetime-extended temporaries.
1145 llvm::erase_if(CleanupStack, [](Cleanup &C) {
1146 return !C.isDestroyedAtEndOf(ScopeKind::FullExpression);
1147 });
1148 }
1149
1150 /// Throw away any remaining cleanups at the end of evaluation. If any
1151 /// cleanups would have had a side-effect, note that as an unmodeled
1152 /// side-effect and return false. Otherwise, return true.
discardCleanups()1153 bool discardCleanups() {
1154 for (Cleanup &C : CleanupStack) {
1155 if (C.hasSideEffect() && !noteSideEffect()) {
1156 CleanupStack.clear();
1157 return false;
1158 }
1159 }
1160 CleanupStack.clear();
1161 return true;
1162 }
1163
1164 private:
getCurrentFrame()1165 interp::Frame *getCurrentFrame() override { return CurrentCall; }
getBottomFrame() const1166 const interp::Frame *getBottomFrame() const override { return &BottomFrame; }
1167
hasActiveDiagnostic()1168 bool hasActiveDiagnostic() override { return HasActiveDiagnostic; }
setActiveDiagnostic(bool Flag)1169 void setActiveDiagnostic(bool Flag) override { HasActiveDiagnostic = Flag; }
1170
setFoldFailureDiagnostic(bool Flag)1171 void setFoldFailureDiagnostic(bool Flag) override {
1172 HasFoldFailureDiagnostic = Flag;
1173 }
1174
getEvalStatus() const1175 Expr::EvalStatus &getEvalStatus() const override { return EvalStatus; }
1176
1177 // If we have a prior diagnostic, it will be noting that the expression
1178 // isn't a constant expression. This diagnostic is more important,
1179 // unless we require this evaluation to produce a constant expression.
1180 //
1181 // FIXME: We might want to show both diagnostics to the user in
1182 // EM_ConstantFold mode.
hasPriorDiagnostic()1183 bool hasPriorDiagnostic() override {
1184 if (!EvalStatus.Diag->empty()) {
1185 switch (EvalMode) {
1186 case EM_ConstantFold:
1187 case EM_IgnoreSideEffects:
1188 if (!HasFoldFailureDiagnostic)
1189 break;
1190 // We've already failed to fold something. Keep that diagnostic.
1191 [[fallthrough]];
1192 case EM_ConstantExpression:
1193 case EM_ConstantExpressionUnevaluated:
1194 setActiveDiagnostic(false);
1195 return true;
1196 }
1197 }
1198 return false;
1199 }
1200
getCallStackDepth()1201 unsigned getCallStackDepth() override { return CallStackDepth; }
1202
1203 public:
1204 /// Should we continue evaluation after encountering a side-effect that we
1205 /// couldn't model?
keepEvaluatingAfterSideEffect()1206 bool keepEvaluatingAfterSideEffect() {
1207 switch (EvalMode) {
1208 case EM_IgnoreSideEffects:
1209 return true;
1210
1211 case EM_ConstantExpression:
1212 case EM_ConstantExpressionUnevaluated:
1213 case EM_ConstantFold:
1214 // By default, assume any side effect might be valid in some other
1215 // evaluation of this expression from a different context.
1216 return checkingPotentialConstantExpression() ||
1217 checkingForUndefinedBehavior();
1218 }
1219 llvm_unreachable("Missed EvalMode case");
1220 }
1221
1222 /// Note that we have had a side-effect, and determine whether we should
1223 /// keep evaluating.
noteSideEffect()1224 bool noteSideEffect() {
1225 EvalStatus.HasSideEffects = true;
1226 return keepEvaluatingAfterSideEffect();
1227 }
1228
1229 /// Should we continue evaluation after encountering undefined behavior?
keepEvaluatingAfterUndefinedBehavior()1230 bool keepEvaluatingAfterUndefinedBehavior() {
1231 switch (EvalMode) {
1232 case EM_IgnoreSideEffects:
1233 case EM_ConstantFold:
1234 return true;
1235
1236 case EM_ConstantExpression:
1237 case EM_ConstantExpressionUnevaluated:
1238 return checkingForUndefinedBehavior();
1239 }
1240 llvm_unreachable("Missed EvalMode case");
1241 }
1242
1243 /// Note that we hit something that was technically undefined behavior, but
1244 /// that we can evaluate past it (such as signed overflow or floating-point
1245 /// division by zero.)
noteUndefinedBehavior()1246 bool noteUndefinedBehavior() override {
1247 EvalStatus.HasUndefinedBehavior = true;
1248 return keepEvaluatingAfterUndefinedBehavior();
1249 }
1250
1251 /// Should we continue evaluation as much as possible after encountering a
1252 /// construct which can't be reduced to a value?
keepEvaluatingAfterFailure() const1253 bool keepEvaluatingAfterFailure() const override {
1254 if (!StepsLeft)
1255 return false;
1256
1257 switch (EvalMode) {
1258 case EM_ConstantExpression:
1259 case EM_ConstantExpressionUnevaluated:
1260 case EM_ConstantFold:
1261 case EM_IgnoreSideEffects:
1262 return checkingPotentialConstantExpression() ||
1263 checkingForUndefinedBehavior();
1264 }
1265 llvm_unreachable("Missed EvalMode case");
1266 }
1267
1268 /// Notes that we failed to evaluate an expression that other expressions
1269 /// directly depend on, and determine if we should keep evaluating. This
1270 /// should only be called if we actually intend to keep evaluating.
1271 ///
1272 /// Call noteSideEffect() instead if we may be able to ignore the value that
1273 /// we failed to evaluate, e.g. if we failed to evaluate Foo() in:
1274 ///
1275 /// (Foo(), 1) // use noteSideEffect
1276 /// (Foo() || true) // use noteSideEffect
1277 /// Foo() + 1 // use noteFailure
noteFailure()1278 [[nodiscard]] bool noteFailure() {
1279 // Failure when evaluating some expression often means there is some
1280 // subexpression whose evaluation was skipped. Therefore, (because we
1281 // don't track whether we skipped an expression when unwinding after an
1282 // evaluation failure) every evaluation failure that bubbles up from a
1283 // subexpression implies that a side-effect has potentially happened. We
1284 // skip setting the HasSideEffects flag to true until we decide to
1285 // continue evaluating after that point, which happens here.
1286 bool KeepGoing = keepEvaluatingAfterFailure();
1287 EvalStatus.HasSideEffects |= KeepGoing;
1288 return KeepGoing;
1289 }
1290
1291 class ArrayInitLoopIndex {
1292 EvalInfo &Info;
1293 uint64_t OuterIndex;
1294
1295 public:
ArrayInitLoopIndex(EvalInfo & Info)1296 ArrayInitLoopIndex(EvalInfo &Info)
1297 : Info(Info), OuterIndex(Info.ArrayInitIndex) {
1298 Info.ArrayInitIndex = 0;
1299 }
~ArrayInitLoopIndex()1300 ~ArrayInitLoopIndex() { Info.ArrayInitIndex = OuterIndex; }
1301
operator uint64_t&()1302 operator uint64_t&() { return Info.ArrayInitIndex; }
1303 };
1304 };
1305
1306 /// Object used to treat all foldable expressions as constant expressions.
1307 struct FoldConstant {
1308 EvalInfo &Info;
1309 bool Enabled;
1310 bool HadNoPriorDiags;
1311 EvalInfo::EvaluationMode OldMode;
1312
FoldConstant__anonbf0ddd820411::FoldConstant1313 explicit FoldConstant(EvalInfo &Info, bool Enabled)
1314 : Info(Info),
1315 Enabled(Enabled),
1316 HadNoPriorDiags(Info.EvalStatus.Diag &&
1317 Info.EvalStatus.Diag->empty() &&
1318 !Info.EvalStatus.HasSideEffects),
1319 OldMode(Info.EvalMode) {
1320 if (Enabled)
1321 Info.EvalMode = EvalInfo::EM_ConstantFold;
1322 }
keepDiagnostics__anonbf0ddd820411::FoldConstant1323 void keepDiagnostics() { Enabled = false; }
~FoldConstant__anonbf0ddd820411::FoldConstant1324 ~FoldConstant() {
1325 if (Enabled && HadNoPriorDiags && !Info.EvalStatus.Diag->empty() &&
1326 !Info.EvalStatus.HasSideEffects)
1327 Info.EvalStatus.Diag->clear();
1328 Info.EvalMode = OldMode;
1329 }
1330 };
1331
1332 /// RAII object used to set the current evaluation mode to ignore
1333 /// side-effects.
1334 struct IgnoreSideEffectsRAII {
1335 EvalInfo &Info;
1336 EvalInfo::EvaluationMode OldMode;
IgnoreSideEffectsRAII__anonbf0ddd820411::IgnoreSideEffectsRAII1337 explicit IgnoreSideEffectsRAII(EvalInfo &Info)
1338 : Info(Info), OldMode(Info.EvalMode) {
1339 Info.EvalMode = EvalInfo::EM_IgnoreSideEffects;
1340 }
1341
~IgnoreSideEffectsRAII__anonbf0ddd820411::IgnoreSideEffectsRAII1342 ~IgnoreSideEffectsRAII() { Info.EvalMode = OldMode; }
1343 };
1344
1345 /// RAII object used to optionally suppress diagnostics and side-effects from
1346 /// a speculative evaluation.
1347 class SpeculativeEvaluationRAII {
1348 EvalInfo *Info = nullptr;
1349 Expr::EvalStatus OldStatus;
1350 unsigned OldSpeculativeEvaluationDepth = 0;
1351
moveFromAndCancel(SpeculativeEvaluationRAII && Other)1352 void moveFromAndCancel(SpeculativeEvaluationRAII &&Other) {
1353 Info = Other.Info;
1354 OldStatus = Other.OldStatus;
1355 OldSpeculativeEvaluationDepth = Other.OldSpeculativeEvaluationDepth;
1356 Other.Info = nullptr;
1357 }
1358
maybeRestoreState()1359 void maybeRestoreState() {
1360 if (!Info)
1361 return;
1362
1363 Info->EvalStatus = OldStatus;
1364 Info->SpeculativeEvaluationDepth = OldSpeculativeEvaluationDepth;
1365 }
1366
1367 public:
1368 SpeculativeEvaluationRAII() = default;
1369
SpeculativeEvaluationRAII(EvalInfo & Info,SmallVectorImpl<PartialDiagnosticAt> * NewDiag=nullptr)1370 SpeculativeEvaluationRAII(
1371 EvalInfo &Info, SmallVectorImpl<PartialDiagnosticAt> *NewDiag = nullptr)
1372 : Info(&Info), OldStatus(Info.EvalStatus),
1373 OldSpeculativeEvaluationDepth(Info.SpeculativeEvaluationDepth) {
1374 Info.EvalStatus.Diag = NewDiag;
1375 Info.SpeculativeEvaluationDepth = Info.CallStackDepth + 1;
1376 }
1377
1378 SpeculativeEvaluationRAII(const SpeculativeEvaluationRAII &Other) = delete;
SpeculativeEvaluationRAII(SpeculativeEvaluationRAII && Other)1379 SpeculativeEvaluationRAII(SpeculativeEvaluationRAII &&Other) {
1380 moveFromAndCancel(std::move(Other));
1381 }
1382
operator =(SpeculativeEvaluationRAII && Other)1383 SpeculativeEvaluationRAII &operator=(SpeculativeEvaluationRAII &&Other) {
1384 maybeRestoreState();
1385 moveFromAndCancel(std::move(Other));
1386 return *this;
1387 }
1388
~SpeculativeEvaluationRAII()1389 ~SpeculativeEvaluationRAII() { maybeRestoreState(); }
1390 };
1391
1392 /// RAII object wrapping a full-expression or block scope, and handling
1393 /// the ending of the lifetime of temporaries created within it.
1394 template<ScopeKind Kind>
1395 class ScopeRAII {
1396 EvalInfo &Info;
1397 unsigned OldStackSize;
1398 public:
ScopeRAII(EvalInfo & Info)1399 ScopeRAII(EvalInfo &Info)
1400 : Info(Info), OldStackSize(Info.CleanupStack.size()) {
1401 // Push a new temporary version. This is needed to distinguish between
1402 // temporaries created in different iterations of a loop.
1403 Info.CurrentCall->pushTempVersion();
1404 }
destroy(bool RunDestructors=true)1405 bool destroy(bool RunDestructors = true) {
1406 bool OK = cleanup(Info, RunDestructors, OldStackSize);
1407 OldStackSize = -1U;
1408 return OK;
1409 }
~ScopeRAII()1410 ~ScopeRAII() {
1411 if (OldStackSize != -1U)
1412 destroy(false);
1413 // Body moved to a static method to encourage the compiler to inline away
1414 // instances of this class.
1415 Info.CurrentCall->popTempVersion();
1416 }
1417 private:
cleanup(EvalInfo & Info,bool RunDestructors,unsigned OldStackSize)1418 static bool cleanup(EvalInfo &Info, bool RunDestructors,
1419 unsigned OldStackSize) {
1420 assert(OldStackSize <= Info.CleanupStack.size() &&
1421 "running cleanups out of order?");
1422
1423 // Run all cleanups for a block scope, and non-lifetime-extended cleanups
1424 // for a full-expression scope.
1425 bool Success = true;
1426 for (unsigned I = Info.CleanupStack.size(); I > OldStackSize; --I) {
1427 if (Info.CleanupStack[I - 1].isDestroyedAtEndOf(Kind)) {
1428 if (!Info.CleanupStack[I - 1].endLifetime(Info, RunDestructors)) {
1429 Success = false;
1430 break;
1431 }
1432 }
1433 }
1434
1435 // Compact any retained cleanups.
1436 auto NewEnd = Info.CleanupStack.begin() + OldStackSize;
1437 if (Kind != ScopeKind::Block)
1438 NewEnd =
1439 std::remove_if(NewEnd, Info.CleanupStack.end(), [](Cleanup &C) {
1440 return C.isDestroyedAtEndOf(Kind);
1441 });
1442 Info.CleanupStack.erase(NewEnd, Info.CleanupStack.end());
1443 return Success;
1444 }
1445 };
1446 typedef ScopeRAII<ScopeKind::Block> BlockScopeRAII;
1447 typedef ScopeRAII<ScopeKind::FullExpression> FullExpressionRAII;
1448 typedef ScopeRAII<ScopeKind::Call> CallScopeRAII;
1449 }
1450
checkSubobject(EvalInfo & Info,const Expr * E,CheckSubobjectKind CSK)1451 bool SubobjectDesignator::checkSubobject(EvalInfo &Info, const Expr *E,
1452 CheckSubobjectKind CSK) {
1453 if (Invalid)
1454 return false;
1455 if (isOnePastTheEnd()) {
1456 Info.CCEDiag(E, diag::note_constexpr_past_end_subobject)
1457 << CSK;
1458 setInvalid();
1459 return false;
1460 }
1461 // Note, we do not diagnose if isMostDerivedAnUnsizedArray(), because there
1462 // must actually be at least one array element; even a VLA cannot have a
1463 // bound of zero. And if our index is nonzero, we already had a CCEDiag.
1464 return true;
1465 }
1466
diagnoseUnsizedArrayPointerArithmetic(EvalInfo & Info,const Expr * E)1467 void SubobjectDesignator::diagnoseUnsizedArrayPointerArithmetic(EvalInfo &Info,
1468 const Expr *E) {
1469 Info.CCEDiag(E, diag::note_constexpr_unsized_array_indexed);
1470 // Do not set the designator as invalid: we can represent this situation,
1471 // and correct handling of __builtin_object_size requires us to do so.
1472 }
1473
diagnosePointerArithmetic(EvalInfo & Info,const Expr * E,const APSInt & N)1474 void SubobjectDesignator::diagnosePointerArithmetic(EvalInfo &Info,
1475 const Expr *E,
1476 const APSInt &N) {
1477 // If we're complaining, we must be able to statically determine the size of
1478 // the most derived array.
1479 if (MostDerivedPathLength == Entries.size() && MostDerivedIsArrayElement)
1480 Info.CCEDiag(E, diag::note_constexpr_array_index)
1481 << N << /*array*/ 0
1482 << static_cast<unsigned>(getMostDerivedArraySize());
1483 else
1484 Info.CCEDiag(E, diag::note_constexpr_array_index)
1485 << N << /*non-array*/ 1;
1486 setInvalid();
1487 }
1488
CallStackFrame(EvalInfo & Info,SourceRange CallRange,const FunctionDecl * Callee,const LValue * This,const Expr * CallExpr,CallRef Call)1489 CallStackFrame::CallStackFrame(EvalInfo &Info, SourceRange CallRange,
1490 const FunctionDecl *Callee, const LValue *This,
1491 const Expr *CallExpr, CallRef Call)
1492 : Info(Info), Caller(Info.CurrentCall), Callee(Callee), This(This),
1493 CallExpr(CallExpr), Arguments(Call), CallRange(CallRange),
1494 Index(Info.NextCallIndex++) {
1495 Info.CurrentCall = this;
1496 ++Info.CallStackDepth;
1497 }
1498
~CallStackFrame()1499 CallStackFrame::~CallStackFrame() {
1500 assert(Info.CurrentCall == this && "calls retired out of order");
1501 --Info.CallStackDepth;
1502 Info.CurrentCall = Caller;
1503 }
1504
isRead(AccessKinds AK)1505 static bool isRead(AccessKinds AK) {
1506 return AK == AK_Read || AK == AK_ReadObjectRepresentation;
1507 }
1508
isModification(AccessKinds AK)1509 static bool isModification(AccessKinds AK) {
1510 switch (AK) {
1511 case AK_Read:
1512 case AK_ReadObjectRepresentation:
1513 case AK_MemberCall:
1514 case AK_DynamicCast:
1515 case AK_TypeId:
1516 return false;
1517 case AK_Assign:
1518 case AK_Increment:
1519 case AK_Decrement:
1520 case AK_Construct:
1521 case AK_Destroy:
1522 return true;
1523 }
1524 llvm_unreachable("unknown access kind");
1525 }
1526
isAnyAccess(AccessKinds AK)1527 static bool isAnyAccess(AccessKinds AK) {
1528 return isRead(AK) || isModification(AK);
1529 }
1530
1531 /// Is this an access per the C++ definition?
isFormalAccess(AccessKinds AK)1532 static bool isFormalAccess(AccessKinds AK) {
1533 return isAnyAccess(AK) && AK != AK_Construct && AK != AK_Destroy;
1534 }
1535
1536 /// Is this kind of axcess valid on an indeterminate object value?
isValidIndeterminateAccess(AccessKinds AK)1537 static bool isValidIndeterminateAccess(AccessKinds AK) {
1538 switch (AK) {
1539 case AK_Read:
1540 case AK_Increment:
1541 case AK_Decrement:
1542 // These need the object's value.
1543 return false;
1544
1545 case AK_ReadObjectRepresentation:
1546 case AK_Assign:
1547 case AK_Construct:
1548 case AK_Destroy:
1549 // Construction and destruction don't need the value.
1550 return true;
1551
1552 case AK_MemberCall:
1553 case AK_DynamicCast:
1554 case AK_TypeId:
1555 // These aren't really meaningful on scalars.
1556 return true;
1557 }
1558 llvm_unreachable("unknown access kind");
1559 }
1560
1561 namespace {
1562 struct ComplexValue {
1563 private:
1564 bool IsInt;
1565
1566 public:
1567 APSInt IntReal, IntImag;
1568 APFloat FloatReal, FloatImag;
1569
ComplexValue__anonbf0ddd820711::ComplexValue1570 ComplexValue() : FloatReal(APFloat::Bogus()), FloatImag(APFloat::Bogus()) {}
1571
makeComplexFloat__anonbf0ddd820711::ComplexValue1572 void makeComplexFloat() { IsInt = false; }
isComplexFloat__anonbf0ddd820711::ComplexValue1573 bool isComplexFloat() const { return !IsInt; }
getComplexFloatReal__anonbf0ddd820711::ComplexValue1574 APFloat &getComplexFloatReal() { return FloatReal; }
getComplexFloatImag__anonbf0ddd820711::ComplexValue1575 APFloat &getComplexFloatImag() { return FloatImag; }
1576
makeComplexInt__anonbf0ddd820711::ComplexValue1577 void makeComplexInt() { IsInt = true; }
isComplexInt__anonbf0ddd820711::ComplexValue1578 bool isComplexInt() const { return IsInt; }
getComplexIntReal__anonbf0ddd820711::ComplexValue1579 APSInt &getComplexIntReal() { return IntReal; }
getComplexIntImag__anonbf0ddd820711::ComplexValue1580 APSInt &getComplexIntImag() { return IntImag; }
1581
moveInto__anonbf0ddd820711::ComplexValue1582 void moveInto(APValue &v) const {
1583 if (isComplexFloat())
1584 v = APValue(FloatReal, FloatImag);
1585 else
1586 v = APValue(IntReal, IntImag);
1587 }
setFrom__anonbf0ddd820711::ComplexValue1588 void setFrom(const APValue &v) {
1589 assert(v.isComplexFloat() || v.isComplexInt());
1590 if (v.isComplexFloat()) {
1591 makeComplexFloat();
1592 FloatReal = v.getComplexFloatReal();
1593 FloatImag = v.getComplexFloatImag();
1594 } else {
1595 makeComplexInt();
1596 IntReal = v.getComplexIntReal();
1597 IntImag = v.getComplexIntImag();
1598 }
1599 }
1600 };
1601
1602 struct LValue {
1603 APValue::LValueBase Base;
1604 CharUnits Offset;
1605 SubobjectDesignator Designator;
1606 bool IsNullPtr : 1;
1607 bool InvalidBase : 1;
1608
getLValueBase__anonbf0ddd820711::LValue1609 const APValue::LValueBase getLValueBase() const { return Base; }
getLValueOffset__anonbf0ddd820711::LValue1610 CharUnits &getLValueOffset() { return Offset; }
getLValueOffset__anonbf0ddd820711::LValue1611 const CharUnits &getLValueOffset() const { return Offset; }
getLValueDesignator__anonbf0ddd820711::LValue1612 SubobjectDesignator &getLValueDesignator() { return Designator; }
getLValueDesignator__anonbf0ddd820711::LValue1613 const SubobjectDesignator &getLValueDesignator() const { return Designator;}
isNullPointer__anonbf0ddd820711::LValue1614 bool isNullPointer() const { return IsNullPtr;}
1615
getLValueCallIndex__anonbf0ddd820711::LValue1616 unsigned getLValueCallIndex() const { return Base.getCallIndex(); }
getLValueVersion__anonbf0ddd820711::LValue1617 unsigned getLValueVersion() const { return Base.getVersion(); }
1618
moveInto__anonbf0ddd820711::LValue1619 void moveInto(APValue &V) const {
1620 if (Designator.Invalid)
1621 V = APValue(Base, Offset, APValue::NoLValuePath(), IsNullPtr);
1622 else {
1623 assert(!InvalidBase && "APValues can't handle invalid LValue bases");
1624 V = APValue(Base, Offset, Designator.Entries,
1625 Designator.IsOnePastTheEnd, IsNullPtr);
1626 }
1627 }
setFrom__anonbf0ddd820711::LValue1628 void setFrom(ASTContext &Ctx, const APValue &V) {
1629 assert(V.isLValue() && "Setting LValue from a non-LValue?");
1630 Base = V.getLValueBase();
1631 Offset = V.getLValueOffset();
1632 InvalidBase = false;
1633 Designator = SubobjectDesignator(Ctx, V);
1634 IsNullPtr = V.isNullPointer();
1635 }
1636
set__anonbf0ddd820711::LValue1637 void set(APValue::LValueBase B, bool BInvalid = false) {
1638 #ifndef NDEBUG
1639 // We only allow a few types of invalid bases. Enforce that here.
1640 if (BInvalid) {
1641 const auto *E = B.get<const Expr *>();
1642 assert((isa<MemberExpr>(E) || tryUnwrapAllocSizeCall(E)) &&
1643 "Unexpected type of invalid base");
1644 }
1645 #endif
1646
1647 Base = B;
1648 Offset = CharUnits::fromQuantity(0);
1649 InvalidBase = BInvalid;
1650 Designator = SubobjectDesignator(getType(B));
1651 IsNullPtr = false;
1652 }
1653
setNull__anonbf0ddd820711::LValue1654 void setNull(ASTContext &Ctx, QualType PointerTy) {
1655 Base = (const ValueDecl *)nullptr;
1656 Offset =
1657 CharUnits::fromQuantity(Ctx.getTargetNullPointerValue(PointerTy));
1658 InvalidBase = false;
1659 Designator = SubobjectDesignator(PointerTy->getPointeeType());
1660 IsNullPtr = true;
1661 }
1662
setInvalid__anonbf0ddd820711::LValue1663 void setInvalid(APValue::LValueBase B, unsigned I = 0) {
1664 set(B, true);
1665 }
1666
toString__anonbf0ddd820711::LValue1667 std::string toString(ASTContext &Ctx, QualType T) const {
1668 APValue Printable;
1669 moveInto(Printable);
1670 return Printable.getAsString(Ctx, T);
1671 }
1672
1673 private:
1674 // Check that this LValue is not based on a null pointer. If it is, produce
1675 // a diagnostic and mark the designator as invalid.
1676 template <typename GenDiagType>
checkNullPointerDiagnosingWith__anonbf0ddd820711::LValue1677 bool checkNullPointerDiagnosingWith(const GenDiagType &GenDiag) {
1678 if (Designator.Invalid)
1679 return false;
1680 if (IsNullPtr) {
1681 GenDiag();
1682 Designator.setInvalid();
1683 return false;
1684 }
1685 return true;
1686 }
1687
1688 public:
checkNullPointer__anonbf0ddd820711::LValue1689 bool checkNullPointer(EvalInfo &Info, const Expr *E,
1690 CheckSubobjectKind CSK) {
1691 return checkNullPointerDiagnosingWith([&Info, E, CSK] {
1692 Info.CCEDiag(E, diag::note_constexpr_null_subobject) << CSK;
1693 });
1694 }
1695
checkNullPointerForFoldAccess__anonbf0ddd820711::LValue1696 bool checkNullPointerForFoldAccess(EvalInfo &Info, const Expr *E,
1697 AccessKinds AK) {
1698 return checkNullPointerDiagnosingWith([&Info, E, AK] {
1699 Info.FFDiag(E, diag::note_constexpr_access_null) << AK;
1700 });
1701 }
1702
1703 // Check this LValue refers to an object. If not, set the designator to be
1704 // invalid and emit a diagnostic.
checkSubobject__anonbf0ddd820711::LValue1705 bool checkSubobject(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK) {
1706 return (CSK == CSK_ArrayToPointer || checkNullPointer(Info, E, CSK)) &&
1707 Designator.checkSubobject(Info, E, CSK);
1708 }
1709
addDecl__anonbf0ddd820711::LValue1710 void addDecl(EvalInfo &Info, const Expr *E,
1711 const Decl *D, bool Virtual = false) {
1712 if (checkSubobject(Info, E, isa<FieldDecl>(D) ? CSK_Field : CSK_Base))
1713 Designator.addDeclUnchecked(D, Virtual);
1714 }
addUnsizedArray__anonbf0ddd820711::LValue1715 void addUnsizedArray(EvalInfo &Info, const Expr *E, QualType ElemTy) {
1716 if (!Designator.Entries.empty()) {
1717 Info.CCEDiag(E, diag::note_constexpr_unsupported_unsized_array);
1718 Designator.setInvalid();
1719 return;
1720 }
1721 if (checkSubobject(Info, E, CSK_ArrayToPointer)) {
1722 assert(getType(Base)->isPointerType() || getType(Base)->isArrayType());
1723 Designator.FirstEntryIsAnUnsizedArray = true;
1724 Designator.addUnsizedArrayUnchecked(ElemTy);
1725 }
1726 }
addArray__anonbf0ddd820711::LValue1727 void addArray(EvalInfo &Info, const Expr *E, const ConstantArrayType *CAT) {
1728 if (checkSubobject(Info, E, CSK_ArrayToPointer))
1729 Designator.addArrayUnchecked(CAT);
1730 }
addComplex__anonbf0ddd820711::LValue1731 void addComplex(EvalInfo &Info, const Expr *E, QualType EltTy, bool Imag) {
1732 if (checkSubobject(Info, E, Imag ? CSK_Imag : CSK_Real))
1733 Designator.addComplexUnchecked(EltTy, Imag);
1734 }
clearIsNullPointer__anonbf0ddd820711::LValue1735 void clearIsNullPointer() {
1736 IsNullPtr = false;
1737 }
adjustOffsetAndIndex__anonbf0ddd820711::LValue1738 void adjustOffsetAndIndex(EvalInfo &Info, const Expr *E,
1739 const APSInt &Index, CharUnits ElementSize) {
1740 // An index of 0 has no effect. (In C, adding 0 to a null pointer is UB,
1741 // but we're not required to diagnose it and it's valid in C++.)
1742 if (!Index)
1743 return;
1744
1745 // Compute the new offset in the appropriate width, wrapping at 64 bits.
1746 // FIXME: When compiling for a 32-bit target, we should use 32-bit
1747 // offsets.
1748 uint64_t Offset64 = Offset.getQuantity();
1749 uint64_t ElemSize64 = ElementSize.getQuantity();
1750 uint64_t Index64 = Index.extOrTrunc(64).getZExtValue();
1751 Offset = CharUnits::fromQuantity(Offset64 + ElemSize64 * Index64);
1752
1753 if (checkNullPointer(Info, E, CSK_ArrayIndex))
1754 Designator.adjustIndex(Info, E, Index);
1755 clearIsNullPointer();
1756 }
adjustOffset__anonbf0ddd820711::LValue1757 void adjustOffset(CharUnits N) {
1758 Offset += N;
1759 if (N.getQuantity())
1760 clearIsNullPointer();
1761 }
1762 };
1763
1764 struct MemberPtr {
MemberPtr__anonbf0ddd820711::MemberPtr1765 MemberPtr() {}
MemberPtr__anonbf0ddd820711::MemberPtr1766 explicit MemberPtr(const ValueDecl *Decl)
1767 : DeclAndIsDerivedMember(Decl, false) {}
1768
1769 /// The member or (direct or indirect) field referred to by this member
1770 /// pointer, or 0 if this is a null member pointer.
getDecl__anonbf0ddd820711::MemberPtr1771 const ValueDecl *getDecl() const {
1772 return DeclAndIsDerivedMember.getPointer();
1773 }
1774 /// Is this actually a member of some type derived from the relevant class?
isDerivedMember__anonbf0ddd820711::MemberPtr1775 bool isDerivedMember() const {
1776 return DeclAndIsDerivedMember.getInt();
1777 }
1778 /// Get the class which the declaration actually lives in.
getContainingRecord__anonbf0ddd820711::MemberPtr1779 const CXXRecordDecl *getContainingRecord() const {
1780 return cast<CXXRecordDecl>(
1781 DeclAndIsDerivedMember.getPointer()->getDeclContext());
1782 }
1783
moveInto__anonbf0ddd820711::MemberPtr1784 void moveInto(APValue &V) const {
1785 V = APValue(getDecl(), isDerivedMember(), Path);
1786 }
setFrom__anonbf0ddd820711::MemberPtr1787 void setFrom(const APValue &V) {
1788 assert(V.isMemberPointer());
1789 DeclAndIsDerivedMember.setPointer(V.getMemberPointerDecl());
1790 DeclAndIsDerivedMember.setInt(V.isMemberPointerToDerivedMember());
1791 Path.clear();
1792 ArrayRef<const CXXRecordDecl*> P = V.getMemberPointerPath();
1793 Path.insert(Path.end(), P.begin(), P.end());
1794 }
1795
1796 /// DeclAndIsDerivedMember - The member declaration, and a flag indicating
1797 /// whether the member is a member of some class derived from the class type
1798 /// of the member pointer.
1799 llvm::PointerIntPair<const ValueDecl*, 1, bool> DeclAndIsDerivedMember;
1800 /// Path - The path of base/derived classes from the member declaration's
1801 /// class (exclusive) to the class type of the member pointer (inclusive).
1802 SmallVector<const CXXRecordDecl*, 4> Path;
1803
1804 /// Perform a cast towards the class of the Decl (either up or down the
1805 /// hierarchy).
castBack__anonbf0ddd820711::MemberPtr1806 bool castBack(const CXXRecordDecl *Class) {
1807 assert(!Path.empty());
1808 const CXXRecordDecl *Expected;
1809 if (Path.size() >= 2)
1810 Expected = Path[Path.size() - 2];
1811 else
1812 Expected = getContainingRecord();
1813 if (Expected->getCanonicalDecl() != Class->getCanonicalDecl()) {
1814 // C++11 [expr.static.cast]p12: In a conversion from (D::*) to (B::*),
1815 // if B does not contain the original member and is not a base or
1816 // derived class of the class containing the original member, the result
1817 // of the cast is undefined.
1818 // C++11 [conv.mem]p2 does not cover this case for a cast from (B::*) to
1819 // (D::*). We consider that to be a language defect.
1820 return false;
1821 }
1822 Path.pop_back();
1823 return true;
1824 }
1825 /// Perform a base-to-derived member pointer cast.
castToDerived__anonbf0ddd820711::MemberPtr1826 bool castToDerived(const CXXRecordDecl *Derived) {
1827 if (!getDecl())
1828 return true;
1829 if (!isDerivedMember()) {
1830 Path.push_back(Derived);
1831 return true;
1832 }
1833 if (!castBack(Derived))
1834 return false;
1835 if (Path.empty())
1836 DeclAndIsDerivedMember.setInt(false);
1837 return true;
1838 }
1839 /// Perform a derived-to-base member pointer cast.
castToBase__anonbf0ddd820711::MemberPtr1840 bool castToBase(const CXXRecordDecl *Base) {
1841 if (!getDecl())
1842 return true;
1843 if (Path.empty())
1844 DeclAndIsDerivedMember.setInt(true);
1845 if (isDerivedMember()) {
1846 Path.push_back(Base);
1847 return true;
1848 }
1849 return castBack(Base);
1850 }
1851 };
1852
1853 /// Compare two member pointers, which are assumed to be of the same type.
operator ==(const MemberPtr & LHS,const MemberPtr & RHS)1854 static bool operator==(const MemberPtr &LHS, const MemberPtr &RHS) {
1855 if (!LHS.getDecl() || !RHS.getDecl())
1856 return !LHS.getDecl() && !RHS.getDecl();
1857 if (LHS.getDecl()->getCanonicalDecl() != RHS.getDecl()->getCanonicalDecl())
1858 return false;
1859 return LHS.Path == RHS.Path;
1860 }
1861 }
1862
1863 static bool Evaluate(APValue &Result, EvalInfo &Info, const Expr *E);
1864 static bool EvaluateInPlace(APValue &Result, EvalInfo &Info,
1865 const LValue &This, const Expr *E,
1866 bool AllowNonLiteralTypes = false);
1867 static bool EvaluateLValue(const Expr *E, LValue &Result, EvalInfo &Info,
1868 bool InvalidBaseOK = false);
1869 static bool EvaluatePointer(const Expr *E, LValue &Result, EvalInfo &Info,
1870 bool InvalidBaseOK = false);
1871 static bool EvaluateMemberPointer(const Expr *E, MemberPtr &Result,
1872 EvalInfo &Info);
1873 static bool EvaluateTemporary(const Expr *E, LValue &Result, EvalInfo &Info);
1874 static bool EvaluateInteger(const Expr *E, APSInt &Result, EvalInfo &Info);
1875 static bool EvaluateIntegerOrLValue(const Expr *E, APValue &Result,
1876 EvalInfo &Info);
1877 static bool EvaluateFloat(const Expr *E, APFloat &Result, EvalInfo &Info);
1878 static bool EvaluateComplex(const Expr *E, ComplexValue &Res, EvalInfo &Info);
1879 static bool EvaluateAtomic(const Expr *E, const LValue *This, APValue &Result,
1880 EvalInfo &Info);
1881 static bool EvaluateAsRValue(EvalInfo &Info, const Expr *E, APValue &Result);
1882 static bool EvaluateBuiltinStrLen(const Expr *E, uint64_t &Result,
1883 EvalInfo &Info);
1884
1885 /// Evaluate an integer or fixed point expression into an APResult.
1886 static bool EvaluateFixedPointOrInteger(const Expr *E, APFixedPoint &Result,
1887 EvalInfo &Info);
1888
1889 /// Evaluate only a fixed point expression into an APResult.
1890 static bool EvaluateFixedPoint(const Expr *E, APFixedPoint &Result,
1891 EvalInfo &Info);
1892
1893 //===----------------------------------------------------------------------===//
1894 // Misc utilities
1895 //===----------------------------------------------------------------------===//
1896
1897 /// Negate an APSInt in place, converting it to a signed form if necessary, and
1898 /// preserving its value (by extending by up to one bit as needed).
negateAsSigned(APSInt & Int)1899 static void negateAsSigned(APSInt &Int) {
1900 if (Int.isUnsigned() || Int.isMinSignedValue()) {
1901 Int = Int.extend(Int.getBitWidth() + 1);
1902 Int.setIsSigned(true);
1903 }
1904 Int = -Int;
1905 }
1906
1907 template<typename KeyT>
createTemporary(const KeyT * Key,QualType T,ScopeKind Scope,LValue & LV)1908 APValue &CallStackFrame::createTemporary(const KeyT *Key, QualType T,
1909 ScopeKind Scope, LValue &LV) {
1910 unsigned Version = getTempVersion();
1911 APValue::LValueBase Base(Key, Index, Version);
1912 LV.set(Base);
1913 return createLocal(Base, Key, T, Scope);
1914 }
1915
1916 /// Allocate storage for a parameter of a function call made in this frame.
createParam(CallRef Args,const ParmVarDecl * PVD,LValue & LV)1917 APValue &CallStackFrame::createParam(CallRef Args, const ParmVarDecl *PVD,
1918 LValue &LV) {
1919 assert(Args.CallIndex == Index && "creating parameter in wrong frame");
1920 APValue::LValueBase Base(PVD, Index, Args.Version);
1921 LV.set(Base);
1922 // We always destroy parameters at the end of the call, even if we'd allow
1923 // them to live to the end of the full-expression at runtime, in order to
1924 // give portable results and match other compilers.
1925 return createLocal(Base, PVD, PVD->getType(), ScopeKind::Call);
1926 }
1927
createLocal(APValue::LValueBase Base,const void * Key,QualType T,ScopeKind Scope)1928 APValue &CallStackFrame::createLocal(APValue::LValueBase Base, const void *Key,
1929 QualType T, ScopeKind Scope) {
1930 assert(Base.getCallIndex() == Index && "lvalue for wrong frame");
1931 unsigned Version = Base.getVersion();
1932 APValue &Result = Temporaries[MapKeyTy(Key, Version)];
1933 assert(Result.isAbsent() && "local created multiple times");
1934
1935 // If we're creating a local immediately in the operand of a speculative
1936 // evaluation, don't register a cleanup to be run outside the speculative
1937 // evaluation context, since we won't actually be able to initialize this
1938 // object.
1939 if (Index <= Info.SpeculativeEvaluationDepth) {
1940 if (T.isDestructedType())
1941 Info.noteSideEffect();
1942 } else {
1943 Info.CleanupStack.push_back(Cleanup(&Result, Base, T, Scope));
1944 }
1945 return Result;
1946 }
1947
createHeapAlloc(const Expr * E,QualType T,LValue & LV)1948 APValue *EvalInfo::createHeapAlloc(const Expr *E, QualType T, LValue &LV) {
1949 if (NumHeapAllocs > DynamicAllocLValue::getMaxIndex()) {
1950 FFDiag(E, diag::note_constexpr_heap_alloc_limit_exceeded);
1951 return nullptr;
1952 }
1953
1954 DynamicAllocLValue DA(NumHeapAllocs++);
1955 LV.set(APValue::LValueBase::getDynamicAlloc(DA, T));
1956 auto Result = HeapAllocs.emplace(std::piecewise_construct,
1957 std::forward_as_tuple(DA), std::tuple<>());
1958 assert(Result.second && "reused a heap alloc index?");
1959 Result.first->second.AllocExpr = E;
1960 return &Result.first->second.Value;
1961 }
1962
1963 /// Produce a string describing the given constexpr call.
describe(raw_ostream & Out) const1964 void CallStackFrame::describe(raw_ostream &Out) const {
1965 unsigned ArgIndex = 0;
1966 bool IsMemberCall =
1967 isa<CXXMethodDecl>(Callee) && !isa<CXXConstructorDecl>(Callee) &&
1968 cast<CXXMethodDecl>(Callee)->isImplicitObjectMemberFunction();
1969
1970 if (!IsMemberCall)
1971 Callee->getNameForDiagnostic(Out, Info.Ctx.getPrintingPolicy(),
1972 /*Qualified=*/false);
1973
1974 if (This && IsMemberCall) {
1975 if (const auto *MCE = dyn_cast_if_present<CXXMemberCallExpr>(CallExpr)) {
1976 const Expr *Object = MCE->getImplicitObjectArgument();
1977 Object->printPretty(Out, /*Helper=*/nullptr, Info.Ctx.getPrintingPolicy(),
1978 /*Indentation=*/0);
1979 if (Object->getType()->isPointerType())
1980 Out << "->";
1981 else
1982 Out << ".";
1983 } else if (const auto *OCE =
1984 dyn_cast_if_present<CXXOperatorCallExpr>(CallExpr)) {
1985 OCE->getArg(0)->printPretty(Out, /*Helper=*/nullptr,
1986 Info.Ctx.getPrintingPolicy(),
1987 /*Indentation=*/0);
1988 Out << ".";
1989 } else {
1990 APValue Val;
1991 This->moveInto(Val);
1992 Val.printPretty(
1993 Out, Info.Ctx,
1994 Info.Ctx.getLValueReferenceType(This->Designator.MostDerivedType));
1995 Out << ".";
1996 }
1997 Callee->getNameForDiagnostic(Out, Info.Ctx.getPrintingPolicy(),
1998 /*Qualified=*/false);
1999 IsMemberCall = false;
2000 }
2001
2002 Out << '(';
2003
2004 for (FunctionDecl::param_const_iterator I = Callee->param_begin(),
2005 E = Callee->param_end(); I != E; ++I, ++ArgIndex) {
2006 if (ArgIndex > (unsigned)IsMemberCall)
2007 Out << ", ";
2008
2009 const ParmVarDecl *Param = *I;
2010 APValue *V = Info.getParamSlot(Arguments, Param);
2011 if (V)
2012 V->printPretty(Out, Info.Ctx, Param->getType());
2013 else
2014 Out << "<...>";
2015
2016 if (ArgIndex == 0 && IsMemberCall)
2017 Out << "->" << *Callee << '(';
2018 }
2019
2020 Out << ')';
2021 }
2022
2023 /// Evaluate an expression to see if it had side-effects, and discard its
2024 /// result.
2025 /// \return \c true if the caller should keep evaluating.
EvaluateIgnoredValue(EvalInfo & Info,const Expr * E)2026 static bool EvaluateIgnoredValue(EvalInfo &Info, const Expr *E) {
2027 assert(!E->isValueDependent());
2028 APValue Scratch;
2029 if (!Evaluate(Scratch, Info, E))
2030 // We don't need the value, but we might have skipped a side effect here.
2031 return Info.noteSideEffect();
2032 return true;
2033 }
2034
2035 /// Should this call expression be treated as a no-op?
IsNoOpCall(const CallExpr * E)2036 static bool IsNoOpCall(const CallExpr *E) {
2037 unsigned Builtin = E->getBuiltinCallee();
2038 return (Builtin == Builtin::BI__builtin___CFStringMakeConstantString ||
2039 Builtin == Builtin::BI__builtin___NSStringMakeConstantString ||
2040 Builtin == Builtin::BI__builtin_function_start);
2041 }
2042
IsGlobalLValue(APValue::LValueBase B)2043 static bool IsGlobalLValue(APValue::LValueBase B) {
2044 // C++11 [expr.const]p3 An address constant expression is a prvalue core
2045 // constant expression of pointer type that evaluates to...
2046
2047 // ... a null pointer value, or a prvalue core constant expression of type
2048 // std::nullptr_t.
2049 if (!B)
2050 return true;
2051
2052 if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) {
2053 // ... the address of an object with static storage duration,
2054 if (const VarDecl *VD = dyn_cast<VarDecl>(D))
2055 return VD->hasGlobalStorage();
2056 if (isa<TemplateParamObjectDecl>(D))
2057 return true;
2058 // ... the address of a function,
2059 // ... the address of a GUID [MS extension],
2060 // ... the address of an unnamed global constant
2061 return isa<FunctionDecl, MSGuidDecl, UnnamedGlobalConstantDecl>(D);
2062 }
2063
2064 if (B.is<TypeInfoLValue>() || B.is<DynamicAllocLValue>())
2065 return true;
2066
2067 const Expr *E = B.get<const Expr*>();
2068 switch (E->getStmtClass()) {
2069 default:
2070 return false;
2071 case Expr::CompoundLiteralExprClass: {
2072 const CompoundLiteralExpr *CLE = cast<CompoundLiteralExpr>(E);
2073 return CLE->isFileScope() && CLE->isLValue();
2074 }
2075 case Expr::MaterializeTemporaryExprClass:
2076 // A materialized temporary might have been lifetime-extended to static
2077 // storage duration.
2078 return cast<MaterializeTemporaryExpr>(E)->getStorageDuration() == SD_Static;
2079 // A string literal has static storage duration.
2080 case Expr::StringLiteralClass:
2081 case Expr::PredefinedExprClass:
2082 case Expr::ObjCStringLiteralClass:
2083 case Expr::ObjCEncodeExprClass:
2084 return true;
2085 case Expr::ObjCBoxedExprClass:
2086 return cast<ObjCBoxedExpr>(E)->isExpressibleAsConstantInitializer();
2087 case Expr::CallExprClass:
2088 return IsNoOpCall(cast<CallExpr>(E));
2089 // For GCC compatibility, &&label has static storage duration.
2090 case Expr::AddrLabelExprClass:
2091 return true;
2092 // A Block literal expression may be used as the initialization value for
2093 // Block variables at global or local static scope.
2094 case Expr::BlockExprClass:
2095 return !cast<BlockExpr>(E)->getBlockDecl()->hasCaptures();
2096 // The APValue generated from a __builtin_source_location will be emitted as a
2097 // literal.
2098 case Expr::SourceLocExprClass:
2099 return true;
2100 case Expr::ImplicitValueInitExprClass:
2101 // FIXME:
2102 // We can never form an lvalue with an implicit value initialization as its
2103 // base through expression evaluation, so these only appear in one case: the
2104 // implicit variable declaration we invent when checking whether a constexpr
2105 // constructor can produce a constant expression. We must assume that such
2106 // an expression might be a global lvalue.
2107 return true;
2108 }
2109 }
2110
GetLValueBaseDecl(const LValue & LVal)2111 static const ValueDecl *GetLValueBaseDecl(const LValue &LVal) {
2112 return LVal.Base.dyn_cast<const ValueDecl*>();
2113 }
2114
IsLiteralLValue(const LValue & Value)2115 static bool IsLiteralLValue(const LValue &Value) {
2116 if (Value.getLValueCallIndex())
2117 return false;
2118 const Expr *E = Value.Base.dyn_cast<const Expr*>();
2119 return E && !isa<MaterializeTemporaryExpr>(E);
2120 }
2121
IsWeakLValue(const LValue & Value)2122 static bool IsWeakLValue(const LValue &Value) {
2123 const ValueDecl *Decl = GetLValueBaseDecl(Value);
2124 return Decl && Decl->isWeak();
2125 }
2126
isZeroSized(const LValue & Value)2127 static bool isZeroSized(const LValue &Value) {
2128 const ValueDecl *Decl = GetLValueBaseDecl(Value);
2129 if (Decl && isa<VarDecl>(Decl)) {
2130 QualType Ty = Decl->getType();
2131 if (Ty->isArrayType())
2132 return Ty->isIncompleteType() ||
2133 Decl->getASTContext().getTypeSize(Ty) == 0;
2134 }
2135 return false;
2136 }
2137
HasSameBase(const LValue & A,const LValue & B)2138 static bool HasSameBase(const LValue &A, const LValue &B) {
2139 if (!A.getLValueBase())
2140 return !B.getLValueBase();
2141 if (!B.getLValueBase())
2142 return false;
2143
2144 if (A.getLValueBase().getOpaqueValue() !=
2145 B.getLValueBase().getOpaqueValue())
2146 return false;
2147
2148 return A.getLValueCallIndex() == B.getLValueCallIndex() &&
2149 A.getLValueVersion() == B.getLValueVersion();
2150 }
2151
NoteLValueLocation(EvalInfo & Info,APValue::LValueBase Base)2152 static void NoteLValueLocation(EvalInfo &Info, APValue::LValueBase Base) {
2153 assert(Base && "no location for a null lvalue");
2154 const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>();
2155
2156 // For a parameter, find the corresponding call stack frame (if it still
2157 // exists), and point at the parameter of the function definition we actually
2158 // invoked.
2159 if (auto *PVD = dyn_cast_or_null<ParmVarDecl>(VD)) {
2160 unsigned Idx = PVD->getFunctionScopeIndex();
2161 for (CallStackFrame *F = Info.CurrentCall; F; F = F->Caller) {
2162 if (F->Arguments.CallIndex == Base.getCallIndex() &&
2163 F->Arguments.Version == Base.getVersion() && F->Callee &&
2164 Idx < F->Callee->getNumParams()) {
2165 VD = F->Callee->getParamDecl(Idx);
2166 break;
2167 }
2168 }
2169 }
2170
2171 if (VD)
2172 Info.Note(VD->getLocation(), diag::note_declared_at);
2173 else if (const Expr *E = Base.dyn_cast<const Expr*>())
2174 Info.Note(E->getExprLoc(), diag::note_constexpr_temporary_here);
2175 else if (DynamicAllocLValue DA = Base.dyn_cast<DynamicAllocLValue>()) {
2176 // FIXME: Produce a note for dangling pointers too.
2177 if (std::optional<DynAlloc *> Alloc = Info.lookupDynamicAlloc(DA))
2178 Info.Note((*Alloc)->AllocExpr->getExprLoc(),
2179 diag::note_constexpr_dynamic_alloc_here);
2180 }
2181
2182 // We have no information to show for a typeid(T) object.
2183 }
2184
2185 enum class CheckEvaluationResultKind {
2186 ConstantExpression,
2187 FullyInitialized,
2188 };
2189
2190 /// Materialized temporaries that we've already checked to determine if they're
2191 /// initializsed by a constant expression.
2192 using CheckedTemporaries =
2193 llvm::SmallPtrSet<const MaterializeTemporaryExpr *, 8>;
2194
2195 static bool CheckEvaluationResult(CheckEvaluationResultKind CERK,
2196 EvalInfo &Info, SourceLocation DiagLoc,
2197 QualType Type, const APValue &Value,
2198 ConstantExprKind Kind,
2199 const FieldDecl *SubobjectDecl,
2200 CheckedTemporaries &CheckedTemps);
2201
2202 /// Check that this reference or pointer core constant expression is a valid
2203 /// value for an address or reference constant expression. Return true if we
2204 /// can fold this expression, whether or not it's a constant expression.
CheckLValueConstantExpression(EvalInfo & Info,SourceLocation Loc,QualType Type,const LValue & LVal,ConstantExprKind Kind,CheckedTemporaries & CheckedTemps)2205 static bool CheckLValueConstantExpression(EvalInfo &Info, SourceLocation Loc,
2206 QualType Type, const LValue &LVal,
2207 ConstantExprKind Kind,
2208 CheckedTemporaries &CheckedTemps) {
2209 bool IsReferenceType = Type->isReferenceType();
2210
2211 APValue::LValueBase Base = LVal.getLValueBase();
2212 const SubobjectDesignator &Designator = LVal.getLValueDesignator();
2213
2214 const Expr *BaseE = Base.dyn_cast<const Expr *>();
2215 const ValueDecl *BaseVD = Base.dyn_cast<const ValueDecl*>();
2216
2217 // Additional restrictions apply in a template argument. We only enforce the
2218 // C++20 restrictions here; additional syntactic and semantic restrictions
2219 // are applied elsewhere.
2220 if (isTemplateArgument(Kind)) {
2221 int InvalidBaseKind = -1;
2222 StringRef Ident;
2223 if (Base.is<TypeInfoLValue>())
2224 InvalidBaseKind = 0;
2225 else if (isa_and_nonnull<StringLiteral>(BaseE))
2226 InvalidBaseKind = 1;
2227 else if (isa_and_nonnull<MaterializeTemporaryExpr>(BaseE) ||
2228 isa_and_nonnull<LifetimeExtendedTemporaryDecl>(BaseVD))
2229 InvalidBaseKind = 2;
2230 else if (auto *PE = dyn_cast_or_null<PredefinedExpr>(BaseE)) {
2231 InvalidBaseKind = 3;
2232 Ident = PE->getIdentKindName();
2233 }
2234
2235 if (InvalidBaseKind != -1) {
2236 Info.FFDiag(Loc, diag::note_constexpr_invalid_template_arg)
2237 << IsReferenceType << !Designator.Entries.empty() << InvalidBaseKind
2238 << Ident;
2239 return false;
2240 }
2241 }
2242
2243 if (auto *FD = dyn_cast_or_null<FunctionDecl>(BaseVD);
2244 FD && FD->isImmediateFunction()) {
2245 Info.FFDiag(Loc, diag::note_consteval_address_accessible)
2246 << !Type->isAnyPointerType();
2247 Info.Note(FD->getLocation(), diag::note_declared_at);
2248 return false;
2249 }
2250
2251 // Check that the object is a global. Note that the fake 'this' object we
2252 // manufacture when checking potential constant expressions is conservatively
2253 // assumed to be global here.
2254 if (!IsGlobalLValue(Base)) {
2255 if (Info.getLangOpts().CPlusPlus11) {
2256 Info.FFDiag(Loc, diag::note_constexpr_non_global, 1)
2257 << IsReferenceType << !Designator.Entries.empty() << !!BaseVD
2258 << BaseVD;
2259 auto *VarD = dyn_cast_or_null<VarDecl>(BaseVD);
2260 if (VarD && VarD->isConstexpr()) {
2261 // Non-static local constexpr variables have unintuitive semantics:
2262 // constexpr int a = 1;
2263 // constexpr const int *p = &a;
2264 // ... is invalid because the address of 'a' is not constant. Suggest
2265 // adding a 'static' in this case.
2266 Info.Note(VarD->getLocation(), diag::note_constexpr_not_static)
2267 << VarD
2268 << FixItHint::CreateInsertion(VarD->getBeginLoc(), "static ");
2269 } else {
2270 NoteLValueLocation(Info, Base);
2271 }
2272 } else {
2273 Info.FFDiag(Loc);
2274 }
2275 // Don't allow references to temporaries to escape.
2276 return false;
2277 }
2278 assert((Info.checkingPotentialConstantExpression() ||
2279 LVal.getLValueCallIndex() == 0) &&
2280 "have call index for global lvalue");
2281
2282 if (Base.is<DynamicAllocLValue>()) {
2283 Info.FFDiag(Loc, diag::note_constexpr_dynamic_alloc)
2284 << IsReferenceType << !Designator.Entries.empty();
2285 NoteLValueLocation(Info, Base);
2286 return false;
2287 }
2288
2289 if (BaseVD) {
2290 if (const VarDecl *Var = dyn_cast<const VarDecl>(BaseVD)) {
2291 // Check if this is a thread-local variable.
2292 if (Var->getTLSKind())
2293 // FIXME: Diagnostic!
2294 return false;
2295
2296 // A dllimport variable never acts like a constant, unless we're
2297 // evaluating a value for use only in name mangling.
2298 if (!isForManglingOnly(Kind) && Var->hasAttr<DLLImportAttr>())
2299 // FIXME: Diagnostic!
2300 return false;
2301
2302 // In CUDA/HIP device compilation, only device side variables have
2303 // constant addresses.
2304 if (Info.getCtx().getLangOpts().CUDA &&
2305 Info.getCtx().getLangOpts().CUDAIsDevice &&
2306 Info.getCtx().CUDAConstantEvalCtx.NoWrongSidedVars) {
2307 if ((!Var->hasAttr<CUDADeviceAttr>() &&
2308 !Var->hasAttr<CUDAConstantAttr>() &&
2309 !Var->getType()->isCUDADeviceBuiltinSurfaceType() &&
2310 !Var->getType()->isCUDADeviceBuiltinTextureType()) ||
2311 Var->hasAttr<HIPManagedAttr>())
2312 return false;
2313 }
2314 }
2315 if (const auto *FD = dyn_cast<const FunctionDecl>(BaseVD)) {
2316 // __declspec(dllimport) must be handled very carefully:
2317 // We must never initialize an expression with the thunk in C++.
2318 // Doing otherwise would allow the same id-expression to yield
2319 // different addresses for the same function in different translation
2320 // units. However, this means that we must dynamically initialize the
2321 // expression with the contents of the import address table at runtime.
2322 //
2323 // The C language has no notion of ODR; furthermore, it has no notion of
2324 // dynamic initialization. This means that we are permitted to
2325 // perform initialization with the address of the thunk.
2326 if (Info.getLangOpts().CPlusPlus && !isForManglingOnly(Kind) &&
2327 FD->hasAttr<DLLImportAttr>())
2328 // FIXME: Diagnostic!
2329 return false;
2330 }
2331 } else if (const auto *MTE =
2332 dyn_cast_or_null<MaterializeTemporaryExpr>(BaseE)) {
2333 if (CheckedTemps.insert(MTE).second) {
2334 QualType TempType = getType(Base);
2335 if (TempType.isDestructedType()) {
2336 Info.FFDiag(MTE->getExprLoc(),
2337 diag::note_constexpr_unsupported_temporary_nontrivial_dtor)
2338 << TempType;
2339 return false;
2340 }
2341
2342 APValue *V = MTE->getOrCreateValue(false);
2343 assert(V && "evasluation result refers to uninitialised temporary");
2344 if (!CheckEvaluationResult(CheckEvaluationResultKind::ConstantExpression,
2345 Info, MTE->getExprLoc(), TempType, *V, Kind,
2346 /*SubobjectDecl=*/nullptr, CheckedTemps))
2347 return false;
2348 }
2349 }
2350
2351 // Allow address constant expressions to be past-the-end pointers. This is
2352 // an extension: the standard requires them to point to an object.
2353 if (!IsReferenceType)
2354 return true;
2355
2356 // A reference constant expression must refer to an object.
2357 if (!Base) {
2358 // FIXME: diagnostic
2359 Info.CCEDiag(Loc);
2360 return true;
2361 }
2362
2363 // Does this refer one past the end of some object?
2364 if (!Designator.Invalid && Designator.isOnePastTheEnd()) {
2365 Info.FFDiag(Loc, diag::note_constexpr_past_end, 1)
2366 << !Designator.Entries.empty() << !!BaseVD << BaseVD;
2367 NoteLValueLocation(Info, Base);
2368 }
2369
2370 return true;
2371 }
2372
2373 /// Member pointers are constant expressions unless they point to a
2374 /// non-virtual dllimport member function.
CheckMemberPointerConstantExpression(EvalInfo & Info,SourceLocation Loc,QualType Type,const APValue & Value,ConstantExprKind Kind)2375 static bool CheckMemberPointerConstantExpression(EvalInfo &Info,
2376 SourceLocation Loc,
2377 QualType Type,
2378 const APValue &Value,
2379 ConstantExprKind Kind) {
2380 const ValueDecl *Member = Value.getMemberPointerDecl();
2381 const auto *FD = dyn_cast_or_null<CXXMethodDecl>(Member);
2382 if (!FD)
2383 return true;
2384 if (FD->isImmediateFunction()) {
2385 Info.FFDiag(Loc, diag::note_consteval_address_accessible) << /*pointer*/ 0;
2386 Info.Note(FD->getLocation(), diag::note_declared_at);
2387 return false;
2388 }
2389 return isForManglingOnly(Kind) || FD->isVirtual() ||
2390 !FD->hasAttr<DLLImportAttr>();
2391 }
2392
2393 /// Check that this core constant expression is of literal type, and if not,
2394 /// produce an appropriate diagnostic.
CheckLiteralType(EvalInfo & Info,const Expr * E,const LValue * This=nullptr)2395 static bool CheckLiteralType(EvalInfo &Info, const Expr *E,
2396 const LValue *This = nullptr) {
2397 if (!E->isPRValue() || E->getType()->isLiteralType(Info.Ctx))
2398 return true;
2399
2400 // C++1y: A constant initializer for an object o [...] may also invoke
2401 // constexpr constructors for o and its subobjects even if those objects
2402 // are of non-literal class types.
2403 //
2404 // C++11 missed this detail for aggregates, so classes like this:
2405 // struct foo_t { union { int i; volatile int j; } u; };
2406 // are not (obviously) initializable like so:
2407 // __attribute__((__require_constant_initialization__))
2408 // static const foo_t x = {{0}};
2409 // because "i" is a subobject with non-literal initialization (due to the
2410 // volatile member of the union). See:
2411 // http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#1677
2412 // Therefore, we use the C++1y behavior.
2413 if (This && Info.EvaluatingDecl == This->getLValueBase())
2414 return true;
2415
2416 // Prvalue constant expressions must be of literal types.
2417 if (Info.getLangOpts().CPlusPlus11)
2418 Info.FFDiag(E, diag::note_constexpr_nonliteral)
2419 << E->getType();
2420 else
2421 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
2422 return false;
2423 }
2424
CheckEvaluationResult(CheckEvaluationResultKind CERK,EvalInfo & Info,SourceLocation DiagLoc,QualType Type,const APValue & Value,ConstantExprKind Kind,const FieldDecl * SubobjectDecl,CheckedTemporaries & CheckedTemps)2425 static bool CheckEvaluationResult(CheckEvaluationResultKind CERK,
2426 EvalInfo &Info, SourceLocation DiagLoc,
2427 QualType Type, const APValue &Value,
2428 ConstantExprKind Kind,
2429 const FieldDecl *SubobjectDecl,
2430 CheckedTemporaries &CheckedTemps) {
2431 if (!Value.hasValue()) {
2432 if (SubobjectDecl) {
2433 Info.FFDiag(DiagLoc, diag::note_constexpr_uninitialized)
2434 << /*(name)*/ 1 << SubobjectDecl;
2435 Info.Note(SubobjectDecl->getLocation(),
2436 diag::note_constexpr_subobject_declared_here);
2437 } else {
2438 Info.FFDiag(DiagLoc, diag::note_constexpr_uninitialized)
2439 << /*of type*/ 0 << Type;
2440 }
2441 return false;
2442 }
2443
2444 // We allow _Atomic(T) to be initialized from anything that T can be
2445 // initialized from.
2446 if (const AtomicType *AT = Type->getAs<AtomicType>())
2447 Type = AT->getValueType();
2448
2449 // Core issue 1454: For a literal constant expression of array or class type,
2450 // each subobject of its value shall have been initialized by a constant
2451 // expression.
2452 if (Value.isArray()) {
2453 QualType EltTy = Type->castAsArrayTypeUnsafe()->getElementType();
2454 for (unsigned I = 0, N = Value.getArrayInitializedElts(); I != N; ++I) {
2455 if (!CheckEvaluationResult(CERK, Info, DiagLoc, EltTy,
2456 Value.getArrayInitializedElt(I), Kind,
2457 SubobjectDecl, CheckedTemps))
2458 return false;
2459 }
2460 if (!Value.hasArrayFiller())
2461 return true;
2462 return CheckEvaluationResult(CERK, Info, DiagLoc, EltTy,
2463 Value.getArrayFiller(), Kind, SubobjectDecl,
2464 CheckedTemps);
2465 }
2466 if (Value.isUnion() && Value.getUnionField()) {
2467 return CheckEvaluationResult(
2468 CERK, Info, DiagLoc, Value.getUnionField()->getType(),
2469 Value.getUnionValue(), Kind, Value.getUnionField(), CheckedTemps);
2470 }
2471 if (Value.isStruct()) {
2472 RecordDecl *RD = Type->castAs<RecordType>()->getDecl();
2473 if (const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(RD)) {
2474 unsigned BaseIndex = 0;
2475 for (const CXXBaseSpecifier &BS : CD->bases()) {
2476 const APValue &BaseValue = Value.getStructBase(BaseIndex);
2477 if (!BaseValue.hasValue()) {
2478 SourceLocation TypeBeginLoc = BS.getBaseTypeLoc();
2479 Info.FFDiag(TypeBeginLoc, diag::note_constexpr_uninitialized_base)
2480 << BS.getType() << SourceRange(TypeBeginLoc, BS.getEndLoc());
2481 return false;
2482 }
2483 if (!CheckEvaluationResult(CERK, Info, DiagLoc, BS.getType(), BaseValue,
2484 Kind, /*SubobjectDecl=*/nullptr,
2485 CheckedTemps))
2486 return false;
2487 ++BaseIndex;
2488 }
2489 }
2490 for (const auto *I : RD->fields()) {
2491 if (I->isUnnamedBitfield())
2492 continue;
2493
2494 if (!CheckEvaluationResult(CERK, Info, DiagLoc, I->getType(),
2495 Value.getStructField(I->getFieldIndex()), Kind,
2496 I, CheckedTemps))
2497 return false;
2498 }
2499 }
2500
2501 if (Value.isLValue() &&
2502 CERK == CheckEvaluationResultKind::ConstantExpression) {
2503 LValue LVal;
2504 LVal.setFrom(Info.Ctx, Value);
2505 return CheckLValueConstantExpression(Info, DiagLoc, Type, LVal, Kind,
2506 CheckedTemps);
2507 }
2508
2509 if (Value.isMemberPointer() &&
2510 CERK == CheckEvaluationResultKind::ConstantExpression)
2511 return CheckMemberPointerConstantExpression(Info, DiagLoc, Type, Value, Kind);
2512
2513 // Everything else is fine.
2514 return true;
2515 }
2516
2517 /// Check that this core constant expression value is a valid value for a
2518 /// constant expression. If not, report an appropriate diagnostic. Does not
2519 /// check that the expression is of literal type.
CheckConstantExpression(EvalInfo & Info,SourceLocation DiagLoc,QualType Type,const APValue & Value,ConstantExprKind Kind)2520 static bool CheckConstantExpression(EvalInfo &Info, SourceLocation DiagLoc,
2521 QualType Type, const APValue &Value,
2522 ConstantExprKind Kind) {
2523 // Nothing to check for a constant expression of type 'cv void'.
2524 if (Type->isVoidType())
2525 return true;
2526
2527 CheckedTemporaries CheckedTemps;
2528 return CheckEvaluationResult(CheckEvaluationResultKind::ConstantExpression,
2529 Info, DiagLoc, Type, Value, Kind,
2530 /*SubobjectDecl=*/nullptr, CheckedTemps);
2531 }
2532
2533 /// Check that this evaluated value is fully-initialized and can be loaded by
2534 /// an lvalue-to-rvalue conversion.
CheckFullyInitialized(EvalInfo & Info,SourceLocation DiagLoc,QualType Type,const APValue & Value)2535 static bool CheckFullyInitialized(EvalInfo &Info, SourceLocation DiagLoc,
2536 QualType Type, const APValue &Value) {
2537 CheckedTemporaries CheckedTemps;
2538 return CheckEvaluationResult(
2539 CheckEvaluationResultKind::FullyInitialized, Info, DiagLoc, Type, Value,
2540 ConstantExprKind::Normal, /*SubobjectDecl=*/nullptr, CheckedTemps);
2541 }
2542
2543 /// Enforce C++2a [expr.const]/4.17, which disallows new-expressions unless
2544 /// "the allocated storage is deallocated within the evaluation".
CheckMemoryLeaks(EvalInfo & Info)2545 static bool CheckMemoryLeaks(EvalInfo &Info) {
2546 if (!Info.HeapAllocs.empty()) {
2547 // We can still fold to a constant despite a compile-time memory leak,
2548 // so long as the heap allocation isn't referenced in the result (we check
2549 // that in CheckConstantExpression).
2550 Info.CCEDiag(Info.HeapAllocs.begin()->second.AllocExpr,
2551 diag::note_constexpr_memory_leak)
2552 << unsigned(Info.HeapAllocs.size() - 1);
2553 }
2554 return true;
2555 }
2556
EvalPointerValueAsBool(const APValue & Value,bool & Result)2557 static bool EvalPointerValueAsBool(const APValue &Value, bool &Result) {
2558 // A null base expression indicates a null pointer. These are always
2559 // evaluatable, and they are false unless the offset is zero.
2560 if (!Value.getLValueBase()) {
2561 // TODO: Should a non-null pointer with an offset of zero evaluate to true?
2562 Result = !Value.getLValueOffset().isZero();
2563 return true;
2564 }
2565
2566 // We have a non-null base. These are generally known to be true, but if it's
2567 // a weak declaration it can be null at runtime.
2568 Result = true;
2569 const ValueDecl *Decl = Value.getLValueBase().dyn_cast<const ValueDecl*>();
2570 return !Decl || !Decl->isWeak();
2571 }
2572
HandleConversionToBool(const APValue & Val,bool & Result)2573 static bool HandleConversionToBool(const APValue &Val, bool &Result) {
2574 // TODO: This function should produce notes if it fails.
2575 switch (Val.getKind()) {
2576 case APValue::None:
2577 case APValue::Indeterminate:
2578 return false;
2579 case APValue::Int:
2580 Result = Val.getInt().getBoolValue();
2581 return true;
2582 case APValue::FixedPoint:
2583 Result = Val.getFixedPoint().getBoolValue();
2584 return true;
2585 case APValue::Float:
2586 Result = !Val.getFloat().isZero();
2587 return true;
2588 case APValue::ComplexInt:
2589 Result = Val.getComplexIntReal().getBoolValue() ||
2590 Val.getComplexIntImag().getBoolValue();
2591 return true;
2592 case APValue::ComplexFloat:
2593 Result = !Val.getComplexFloatReal().isZero() ||
2594 !Val.getComplexFloatImag().isZero();
2595 return true;
2596 case APValue::LValue:
2597 return EvalPointerValueAsBool(Val, Result);
2598 case APValue::MemberPointer:
2599 if (Val.getMemberPointerDecl() && Val.getMemberPointerDecl()->isWeak()) {
2600 return false;
2601 }
2602 Result = Val.getMemberPointerDecl();
2603 return true;
2604 case APValue::Vector:
2605 case APValue::Array:
2606 case APValue::Struct:
2607 case APValue::Union:
2608 case APValue::AddrLabelDiff:
2609 return false;
2610 }
2611
2612 llvm_unreachable("unknown APValue kind");
2613 }
2614
EvaluateAsBooleanCondition(const Expr * E,bool & Result,EvalInfo & Info)2615 static bool EvaluateAsBooleanCondition(const Expr *E, bool &Result,
2616 EvalInfo &Info) {
2617 assert(!E->isValueDependent());
2618 assert(E->isPRValue() && "missing lvalue-to-rvalue conv in bool condition");
2619 APValue Val;
2620 if (!Evaluate(Val, Info, E))
2621 return false;
2622 return HandleConversionToBool(Val, Result);
2623 }
2624
2625 template<typename T>
HandleOverflow(EvalInfo & Info,const Expr * E,const T & SrcValue,QualType DestType)2626 static bool HandleOverflow(EvalInfo &Info, const Expr *E,
2627 const T &SrcValue, QualType DestType) {
2628 Info.CCEDiag(E, diag::note_constexpr_overflow)
2629 << SrcValue << DestType;
2630 return Info.noteUndefinedBehavior();
2631 }
2632
HandleFloatToIntCast(EvalInfo & Info,const Expr * E,QualType SrcType,const APFloat & Value,QualType DestType,APSInt & Result)2633 static bool HandleFloatToIntCast(EvalInfo &Info, const Expr *E,
2634 QualType SrcType, const APFloat &Value,
2635 QualType DestType, APSInt &Result) {
2636 unsigned DestWidth = Info.Ctx.getIntWidth(DestType);
2637 // Determine whether we are converting to unsigned or signed.
2638 bool DestSigned = DestType->isSignedIntegerOrEnumerationType();
2639
2640 Result = APSInt(DestWidth, !DestSigned);
2641 bool ignored;
2642 if (Value.convertToInteger(Result, llvm::APFloat::rmTowardZero, &ignored)
2643 & APFloat::opInvalidOp)
2644 return HandleOverflow(Info, E, Value, DestType);
2645 return true;
2646 }
2647
2648 /// Get rounding mode to use in evaluation of the specified expression.
2649 ///
2650 /// If rounding mode is unknown at compile time, still try to evaluate the
2651 /// expression. If the result is exact, it does not depend on rounding mode.
2652 /// So return "tonearest" mode instead of "dynamic".
getActiveRoundingMode(EvalInfo & Info,const Expr * E)2653 static llvm::RoundingMode getActiveRoundingMode(EvalInfo &Info, const Expr *E) {
2654 llvm::RoundingMode RM =
2655 E->getFPFeaturesInEffect(Info.Ctx.getLangOpts()).getRoundingMode();
2656 if (RM == llvm::RoundingMode::Dynamic)
2657 RM = llvm::RoundingMode::NearestTiesToEven;
2658 return RM;
2659 }
2660
2661 /// Check if the given evaluation result is allowed for constant evaluation.
checkFloatingPointResult(EvalInfo & Info,const Expr * E,APFloat::opStatus St)2662 static bool checkFloatingPointResult(EvalInfo &Info, const Expr *E,
2663 APFloat::opStatus St) {
2664 // In a constant context, assume that any dynamic rounding mode or FP
2665 // exception state matches the default floating-point environment.
2666 if (Info.InConstantContext)
2667 return true;
2668
2669 FPOptions FPO = E->getFPFeaturesInEffect(Info.Ctx.getLangOpts());
2670 if ((St & APFloat::opInexact) &&
2671 FPO.getRoundingMode() == llvm::RoundingMode::Dynamic) {
2672 // Inexact result means that it depends on rounding mode. If the requested
2673 // mode is dynamic, the evaluation cannot be made in compile time.
2674 Info.FFDiag(E, diag::note_constexpr_dynamic_rounding);
2675 return false;
2676 }
2677
2678 if ((St != APFloat::opOK) &&
2679 (FPO.getRoundingMode() == llvm::RoundingMode::Dynamic ||
2680 FPO.getExceptionMode() != LangOptions::FPE_Ignore ||
2681 FPO.getAllowFEnvAccess())) {
2682 Info.FFDiag(E, diag::note_constexpr_float_arithmetic_strict);
2683 return false;
2684 }
2685
2686 if ((St & APFloat::opStatus::opInvalidOp) &&
2687 FPO.getExceptionMode() != LangOptions::FPE_Ignore) {
2688 // There is no usefully definable result.
2689 Info.FFDiag(E);
2690 return false;
2691 }
2692
2693 // FIXME: if:
2694 // - evaluation triggered other FP exception, and
2695 // - exception mode is not "ignore", and
2696 // - the expression being evaluated is not a part of global variable
2697 // initializer,
2698 // the evaluation probably need to be rejected.
2699 return true;
2700 }
2701
HandleFloatToFloatCast(EvalInfo & Info,const Expr * E,QualType SrcType,QualType DestType,APFloat & Result)2702 static bool HandleFloatToFloatCast(EvalInfo &Info, const Expr *E,
2703 QualType SrcType, QualType DestType,
2704 APFloat &Result) {
2705 assert(isa<CastExpr>(E) || isa<CompoundAssignOperator>(E));
2706 llvm::RoundingMode RM = getActiveRoundingMode(Info, E);
2707 APFloat::opStatus St;
2708 APFloat Value = Result;
2709 bool ignored;
2710 St = Result.convert(Info.Ctx.getFloatTypeSemantics(DestType), RM, &ignored);
2711 return checkFloatingPointResult(Info, E, St);
2712 }
2713
HandleIntToIntCast(EvalInfo & Info,const Expr * E,QualType DestType,QualType SrcType,const APSInt & Value)2714 static APSInt HandleIntToIntCast(EvalInfo &Info, const Expr *E,
2715 QualType DestType, QualType SrcType,
2716 const APSInt &Value) {
2717 unsigned DestWidth = Info.Ctx.getIntWidth(DestType);
2718 // Figure out if this is a truncate, extend or noop cast.
2719 // If the input is signed, do a sign extend, noop, or truncate.
2720 APSInt Result = Value.extOrTrunc(DestWidth);
2721 Result.setIsUnsigned(DestType->isUnsignedIntegerOrEnumerationType());
2722 if (DestType->isBooleanType())
2723 Result = Value.getBoolValue();
2724 return Result;
2725 }
2726
HandleIntToFloatCast(EvalInfo & Info,const Expr * E,const FPOptions FPO,QualType SrcType,const APSInt & Value,QualType DestType,APFloat & Result)2727 static bool HandleIntToFloatCast(EvalInfo &Info, const Expr *E,
2728 const FPOptions FPO,
2729 QualType SrcType, const APSInt &Value,
2730 QualType DestType, APFloat &Result) {
2731 Result = APFloat(Info.Ctx.getFloatTypeSemantics(DestType), 1);
2732 llvm::RoundingMode RM = getActiveRoundingMode(Info, E);
2733 APFloat::opStatus St = Result.convertFromAPInt(Value, Value.isSigned(), RM);
2734 return checkFloatingPointResult(Info, E, St);
2735 }
2736
truncateBitfieldValue(EvalInfo & Info,const Expr * E,APValue & Value,const FieldDecl * FD)2737 static bool truncateBitfieldValue(EvalInfo &Info, const Expr *E,
2738 APValue &Value, const FieldDecl *FD) {
2739 assert(FD->isBitField() && "truncateBitfieldValue on non-bitfield");
2740
2741 if (!Value.isInt()) {
2742 // Trying to store a pointer-cast-to-integer into a bitfield.
2743 // FIXME: In this case, we should provide the diagnostic for casting
2744 // a pointer to an integer.
2745 assert(Value.isLValue() && "integral value neither int nor lvalue?");
2746 Info.FFDiag(E);
2747 return false;
2748 }
2749
2750 APSInt &Int = Value.getInt();
2751 unsigned OldBitWidth = Int.getBitWidth();
2752 unsigned NewBitWidth = FD->getBitWidthValue(Info.Ctx);
2753 if (NewBitWidth < OldBitWidth)
2754 Int = Int.trunc(NewBitWidth).extend(OldBitWidth);
2755 return true;
2756 }
2757
2758 /// Perform the given integer operation, which is known to need at most BitWidth
2759 /// bits, and check for overflow in the original type (if that type was not an
2760 /// unsigned type).
2761 template<typename Operation>
CheckedIntArithmetic(EvalInfo & Info,const Expr * E,const APSInt & LHS,const APSInt & RHS,unsigned BitWidth,Operation Op,APSInt & Result)2762 static bool CheckedIntArithmetic(EvalInfo &Info, const Expr *E,
2763 const APSInt &LHS, const APSInt &RHS,
2764 unsigned BitWidth, Operation Op,
2765 APSInt &Result) {
2766 if (LHS.isUnsigned()) {
2767 Result = Op(LHS, RHS);
2768 return true;
2769 }
2770
2771 APSInt Value(Op(LHS.extend(BitWidth), RHS.extend(BitWidth)), false);
2772 Result = Value.trunc(LHS.getBitWidth());
2773 if (Result.extend(BitWidth) != Value) {
2774 if (Info.checkingForUndefinedBehavior())
2775 Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
2776 diag::warn_integer_constant_overflow)
2777 << toString(Result, 10) << E->getType() << E->getSourceRange();
2778 return HandleOverflow(Info, E, Value, E->getType());
2779 }
2780 return true;
2781 }
2782
2783 /// Perform the given binary integer operation.
handleIntIntBinOp(EvalInfo & Info,const BinaryOperator * E,const APSInt & LHS,BinaryOperatorKind Opcode,APSInt RHS,APSInt & Result)2784 static bool handleIntIntBinOp(EvalInfo &Info, const BinaryOperator *E,
2785 const APSInt &LHS, BinaryOperatorKind Opcode,
2786 APSInt RHS, APSInt &Result) {
2787 bool HandleOverflowResult = true;
2788 switch (Opcode) {
2789 default:
2790 Info.FFDiag(E);
2791 return false;
2792 case BO_Mul:
2793 return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() * 2,
2794 std::multiplies<APSInt>(), Result);
2795 case BO_Add:
2796 return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1,
2797 std::plus<APSInt>(), Result);
2798 case BO_Sub:
2799 return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1,
2800 std::minus<APSInt>(), Result);
2801 case BO_And: Result = LHS & RHS; return true;
2802 case BO_Xor: Result = LHS ^ RHS; return true;
2803 case BO_Or: Result = LHS | RHS; return true;
2804 case BO_Div:
2805 case BO_Rem:
2806 if (RHS == 0) {
2807 Info.FFDiag(E, diag::note_expr_divide_by_zero)
2808 << E->getRHS()->getSourceRange();
2809 return false;
2810 }
2811 // Check for overflow case: INT_MIN / -1 or INT_MIN % -1. APSInt supports
2812 // this operation and gives the two's complement result.
2813 if (RHS.isNegative() && RHS.isAllOnes() && LHS.isSigned() &&
2814 LHS.isMinSignedValue())
2815 HandleOverflowResult = HandleOverflow(
2816 Info, E, -LHS.extend(LHS.getBitWidth() + 1), E->getType());
2817 Result = (Opcode == BO_Rem ? LHS % RHS : LHS / RHS);
2818 return HandleOverflowResult;
2819 case BO_Shl: {
2820 if (Info.getLangOpts().OpenCL)
2821 // OpenCL 6.3j: shift values are effectively % word size of LHS.
2822 RHS &= APSInt(llvm::APInt(RHS.getBitWidth(),
2823 static_cast<uint64_t>(LHS.getBitWidth() - 1)),
2824 RHS.isUnsigned());
2825 else if (RHS.isSigned() && RHS.isNegative()) {
2826 // During constant-folding, a negative shift is an opposite shift. Such
2827 // a shift is not a constant expression.
2828 Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHS;
2829 RHS = -RHS;
2830 goto shift_right;
2831 }
2832 shift_left:
2833 // C++11 [expr.shift]p1: Shift width must be less than the bit width of
2834 // the shifted type.
2835 unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1);
2836 if (SA != RHS) {
2837 Info.CCEDiag(E, diag::note_constexpr_large_shift)
2838 << RHS << E->getType() << LHS.getBitWidth();
2839 } else if (LHS.isSigned() && !Info.getLangOpts().CPlusPlus20) {
2840 // C++11 [expr.shift]p2: A signed left shift must have a non-negative
2841 // operand, and must not overflow the corresponding unsigned type.
2842 // C++2a [expr.shift]p2: E1 << E2 is the unique value congruent to
2843 // E1 x 2^E2 module 2^N.
2844 if (LHS.isNegative())
2845 Info.CCEDiag(E, diag::note_constexpr_lshift_of_negative) << LHS;
2846 else if (LHS.countl_zero() < SA)
2847 Info.CCEDiag(E, diag::note_constexpr_lshift_discards);
2848 }
2849 Result = LHS << SA;
2850 return true;
2851 }
2852 case BO_Shr: {
2853 if (Info.getLangOpts().OpenCL)
2854 // OpenCL 6.3j: shift values are effectively % word size of LHS.
2855 RHS &= APSInt(llvm::APInt(RHS.getBitWidth(),
2856 static_cast<uint64_t>(LHS.getBitWidth() - 1)),
2857 RHS.isUnsigned());
2858 else if (RHS.isSigned() && RHS.isNegative()) {
2859 // During constant-folding, a negative shift is an opposite shift. Such a
2860 // shift is not a constant expression.
2861 Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHS;
2862 RHS = -RHS;
2863 goto shift_left;
2864 }
2865 shift_right:
2866 // C++11 [expr.shift]p1: Shift width must be less than the bit width of the
2867 // shifted type.
2868 unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1);
2869 if (SA != RHS)
2870 Info.CCEDiag(E, diag::note_constexpr_large_shift)
2871 << RHS << E->getType() << LHS.getBitWidth();
2872 Result = LHS >> SA;
2873 return true;
2874 }
2875
2876 case BO_LT: Result = LHS < RHS; return true;
2877 case BO_GT: Result = LHS > RHS; return true;
2878 case BO_LE: Result = LHS <= RHS; return true;
2879 case BO_GE: Result = LHS >= RHS; return true;
2880 case BO_EQ: Result = LHS == RHS; return true;
2881 case BO_NE: Result = LHS != RHS; return true;
2882 case BO_Cmp:
2883 llvm_unreachable("BO_Cmp should be handled elsewhere");
2884 }
2885 }
2886
2887 /// Perform the given binary floating-point operation, in-place, on LHS.
handleFloatFloatBinOp(EvalInfo & Info,const BinaryOperator * E,APFloat & LHS,BinaryOperatorKind Opcode,const APFloat & RHS)2888 static bool handleFloatFloatBinOp(EvalInfo &Info, const BinaryOperator *E,
2889 APFloat &LHS, BinaryOperatorKind Opcode,
2890 const APFloat &RHS) {
2891 llvm::RoundingMode RM = getActiveRoundingMode(Info, E);
2892 APFloat::opStatus St;
2893 switch (Opcode) {
2894 default:
2895 Info.FFDiag(E);
2896 return false;
2897 case BO_Mul:
2898 St = LHS.multiply(RHS, RM);
2899 break;
2900 case BO_Add:
2901 St = LHS.add(RHS, RM);
2902 break;
2903 case BO_Sub:
2904 St = LHS.subtract(RHS, RM);
2905 break;
2906 case BO_Div:
2907 // [expr.mul]p4:
2908 // If the second operand of / or % is zero the behavior is undefined.
2909 if (RHS.isZero())
2910 Info.CCEDiag(E, diag::note_expr_divide_by_zero);
2911 St = LHS.divide(RHS, RM);
2912 break;
2913 }
2914
2915 // [expr.pre]p4:
2916 // If during the evaluation of an expression, the result is not
2917 // mathematically defined [...], the behavior is undefined.
2918 // FIXME: C++ rules require us to not conform to IEEE 754 here.
2919 if (LHS.isNaN()) {
2920 Info.CCEDiag(E, diag::note_constexpr_float_arithmetic) << LHS.isNaN();
2921 return Info.noteUndefinedBehavior();
2922 }
2923
2924 return checkFloatingPointResult(Info, E, St);
2925 }
2926
handleLogicalOpForVector(const APInt & LHSValue,BinaryOperatorKind Opcode,const APInt & RHSValue,APInt & Result)2927 static bool handleLogicalOpForVector(const APInt &LHSValue,
2928 BinaryOperatorKind Opcode,
2929 const APInt &RHSValue, APInt &Result) {
2930 bool LHS = (LHSValue != 0);
2931 bool RHS = (RHSValue != 0);
2932
2933 if (Opcode == BO_LAnd)
2934 Result = LHS && RHS;
2935 else
2936 Result = LHS || RHS;
2937 return true;
2938 }
handleLogicalOpForVector(const APFloat & LHSValue,BinaryOperatorKind Opcode,const APFloat & RHSValue,APInt & Result)2939 static bool handleLogicalOpForVector(const APFloat &LHSValue,
2940 BinaryOperatorKind Opcode,
2941 const APFloat &RHSValue, APInt &Result) {
2942 bool LHS = !LHSValue.isZero();
2943 bool RHS = !RHSValue.isZero();
2944
2945 if (Opcode == BO_LAnd)
2946 Result = LHS && RHS;
2947 else
2948 Result = LHS || RHS;
2949 return true;
2950 }
2951
handleLogicalOpForVector(const APValue & LHSValue,BinaryOperatorKind Opcode,const APValue & RHSValue,APInt & Result)2952 static bool handleLogicalOpForVector(const APValue &LHSValue,
2953 BinaryOperatorKind Opcode,
2954 const APValue &RHSValue, APInt &Result) {
2955 // The result is always an int type, however operands match the first.
2956 if (LHSValue.getKind() == APValue::Int)
2957 return handleLogicalOpForVector(LHSValue.getInt(), Opcode,
2958 RHSValue.getInt(), Result);
2959 assert(LHSValue.getKind() == APValue::Float && "Should be no other options");
2960 return handleLogicalOpForVector(LHSValue.getFloat(), Opcode,
2961 RHSValue.getFloat(), Result);
2962 }
2963
2964 template <typename APTy>
2965 static bool
handleCompareOpForVectorHelper(const APTy & LHSValue,BinaryOperatorKind Opcode,const APTy & RHSValue,APInt & Result)2966 handleCompareOpForVectorHelper(const APTy &LHSValue, BinaryOperatorKind Opcode,
2967 const APTy &RHSValue, APInt &Result) {
2968 switch (Opcode) {
2969 default:
2970 llvm_unreachable("unsupported binary operator");
2971 case BO_EQ:
2972 Result = (LHSValue == RHSValue);
2973 break;
2974 case BO_NE:
2975 Result = (LHSValue != RHSValue);
2976 break;
2977 case BO_LT:
2978 Result = (LHSValue < RHSValue);
2979 break;
2980 case BO_GT:
2981 Result = (LHSValue > RHSValue);
2982 break;
2983 case BO_LE:
2984 Result = (LHSValue <= RHSValue);
2985 break;
2986 case BO_GE:
2987 Result = (LHSValue >= RHSValue);
2988 break;
2989 }
2990
2991 // The boolean operations on these vector types use an instruction that
2992 // results in a mask of '-1' for the 'truth' value. Ensure that we negate 1
2993 // to -1 to make sure that we produce the correct value.
2994 Result.negate();
2995
2996 return true;
2997 }
2998
handleCompareOpForVector(const APValue & LHSValue,BinaryOperatorKind Opcode,const APValue & RHSValue,APInt & Result)2999 static bool handleCompareOpForVector(const APValue &LHSValue,
3000 BinaryOperatorKind Opcode,
3001 const APValue &RHSValue, APInt &Result) {
3002 // The result is always an int type, however operands match the first.
3003 if (LHSValue.getKind() == APValue::Int)
3004 return handleCompareOpForVectorHelper(LHSValue.getInt(), Opcode,
3005 RHSValue.getInt(), Result);
3006 assert(LHSValue.getKind() == APValue::Float && "Should be no other options");
3007 return handleCompareOpForVectorHelper(LHSValue.getFloat(), Opcode,
3008 RHSValue.getFloat(), Result);
3009 }
3010
3011 // Perform binary operations for vector types, in place on the LHS.
handleVectorVectorBinOp(EvalInfo & Info,const BinaryOperator * E,BinaryOperatorKind Opcode,APValue & LHSValue,const APValue & RHSValue)3012 static bool handleVectorVectorBinOp(EvalInfo &Info, const BinaryOperator *E,
3013 BinaryOperatorKind Opcode,
3014 APValue &LHSValue,
3015 const APValue &RHSValue) {
3016 assert(Opcode != BO_PtrMemD && Opcode != BO_PtrMemI &&
3017 "Operation not supported on vector types");
3018
3019 const auto *VT = E->getType()->castAs<VectorType>();
3020 unsigned NumElements = VT->getNumElements();
3021 QualType EltTy = VT->getElementType();
3022
3023 // In the cases (typically C as I've observed) where we aren't evaluating
3024 // constexpr but are checking for cases where the LHS isn't yet evaluatable,
3025 // just give up.
3026 if (!LHSValue.isVector()) {
3027 assert(LHSValue.isLValue() &&
3028 "A vector result that isn't a vector OR uncalculated LValue");
3029 Info.FFDiag(E);
3030 return false;
3031 }
3032
3033 assert(LHSValue.getVectorLength() == NumElements &&
3034 RHSValue.getVectorLength() == NumElements && "Different vector sizes");
3035
3036 SmallVector<APValue, 4> ResultElements;
3037
3038 for (unsigned EltNum = 0; EltNum < NumElements; ++EltNum) {
3039 APValue LHSElt = LHSValue.getVectorElt(EltNum);
3040 APValue RHSElt = RHSValue.getVectorElt(EltNum);
3041
3042 if (EltTy->isIntegerType()) {
3043 APSInt EltResult{Info.Ctx.getIntWidth(EltTy),
3044 EltTy->isUnsignedIntegerType()};
3045 bool Success = true;
3046
3047 if (BinaryOperator::isLogicalOp(Opcode))
3048 Success = handleLogicalOpForVector(LHSElt, Opcode, RHSElt, EltResult);
3049 else if (BinaryOperator::isComparisonOp(Opcode))
3050 Success = handleCompareOpForVector(LHSElt, Opcode, RHSElt, EltResult);
3051 else
3052 Success = handleIntIntBinOp(Info, E, LHSElt.getInt(), Opcode,
3053 RHSElt.getInt(), EltResult);
3054
3055 if (!Success) {
3056 Info.FFDiag(E);
3057 return false;
3058 }
3059 ResultElements.emplace_back(EltResult);
3060
3061 } else if (EltTy->isFloatingType()) {
3062 assert(LHSElt.getKind() == APValue::Float &&
3063 RHSElt.getKind() == APValue::Float &&
3064 "Mismatched LHS/RHS/Result Type");
3065 APFloat LHSFloat = LHSElt.getFloat();
3066
3067 if (!handleFloatFloatBinOp(Info, E, LHSFloat, Opcode,
3068 RHSElt.getFloat())) {
3069 Info.FFDiag(E);
3070 return false;
3071 }
3072
3073 ResultElements.emplace_back(LHSFloat);
3074 }
3075 }
3076
3077 LHSValue = APValue(ResultElements.data(), ResultElements.size());
3078 return true;
3079 }
3080
3081 /// Cast an lvalue referring to a base subobject to a derived class, by
3082 /// truncating the lvalue's path to the given length.
CastToDerivedClass(EvalInfo & Info,const Expr * E,LValue & Result,const RecordDecl * TruncatedType,unsigned TruncatedElements)3083 static bool CastToDerivedClass(EvalInfo &Info, const Expr *E, LValue &Result,
3084 const RecordDecl *TruncatedType,
3085 unsigned TruncatedElements) {
3086 SubobjectDesignator &D = Result.Designator;
3087
3088 // Check we actually point to a derived class object.
3089 if (TruncatedElements == D.Entries.size())
3090 return true;
3091 assert(TruncatedElements >= D.MostDerivedPathLength &&
3092 "not casting to a derived class");
3093 if (!Result.checkSubobject(Info, E, CSK_Derived))
3094 return false;
3095
3096 // Truncate the path to the subobject, and remove any derived-to-base offsets.
3097 const RecordDecl *RD = TruncatedType;
3098 for (unsigned I = TruncatedElements, N = D.Entries.size(); I != N; ++I) {
3099 if (RD->isInvalidDecl()) return false;
3100 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
3101 const CXXRecordDecl *Base = getAsBaseClass(D.Entries[I]);
3102 if (isVirtualBaseClass(D.Entries[I]))
3103 Result.Offset -= Layout.getVBaseClassOffset(Base);
3104 else
3105 Result.Offset -= Layout.getBaseClassOffset(Base);
3106 RD = Base;
3107 }
3108 D.Entries.resize(TruncatedElements);
3109 return true;
3110 }
3111
HandleLValueDirectBase(EvalInfo & Info,const Expr * E,LValue & Obj,const CXXRecordDecl * Derived,const CXXRecordDecl * Base,const ASTRecordLayout * RL=nullptr)3112 static bool HandleLValueDirectBase(EvalInfo &Info, const Expr *E, LValue &Obj,
3113 const CXXRecordDecl *Derived,
3114 const CXXRecordDecl *Base,
3115 const ASTRecordLayout *RL = nullptr) {
3116 if (!RL) {
3117 if (Derived->isInvalidDecl()) return false;
3118 RL = &Info.Ctx.getASTRecordLayout(Derived);
3119 }
3120
3121 Obj.getLValueOffset() += RL->getBaseClassOffset(Base);
3122 Obj.addDecl(Info, E, Base, /*Virtual*/ false);
3123 return true;
3124 }
3125
HandleLValueBase(EvalInfo & Info,const Expr * E,LValue & Obj,const CXXRecordDecl * DerivedDecl,const CXXBaseSpecifier * Base)3126 static bool HandleLValueBase(EvalInfo &Info, const Expr *E, LValue &Obj,
3127 const CXXRecordDecl *DerivedDecl,
3128 const CXXBaseSpecifier *Base) {
3129 const CXXRecordDecl *BaseDecl = Base->getType()->getAsCXXRecordDecl();
3130
3131 if (!Base->isVirtual())
3132 return HandleLValueDirectBase(Info, E, Obj, DerivedDecl, BaseDecl);
3133
3134 SubobjectDesignator &D = Obj.Designator;
3135 if (D.Invalid)
3136 return false;
3137
3138 // Extract most-derived object and corresponding type.
3139 DerivedDecl = D.MostDerivedType->getAsCXXRecordDecl();
3140 if (!CastToDerivedClass(Info, E, Obj, DerivedDecl, D.MostDerivedPathLength))
3141 return false;
3142
3143 // Find the virtual base class.
3144 if (DerivedDecl->isInvalidDecl()) return false;
3145 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(DerivedDecl);
3146 Obj.getLValueOffset() += Layout.getVBaseClassOffset(BaseDecl);
3147 Obj.addDecl(Info, E, BaseDecl, /*Virtual*/ true);
3148 return true;
3149 }
3150
HandleLValueBasePath(EvalInfo & Info,const CastExpr * E,QualType Type,LValue & Result)3151 static bool HandleLValueBasePath(EvalInfo &Info, const CastExpr *E,
3152 QualType Type, LValue &Result) {
3153 for (CastExpr::path_const_iterator PathI = E->path_begin(),
3154 PathE = E->path_end();
3155 PathI != PathE; ++PathI) {
3156 if (!HandleLValueBase(Info, E, Result, Type->getAsCXXRecordDecl(),
3157 *PathI))
3158 return false;
3159 Type = (*PathI)->getType();
3160 }
3161 return true;
3162 }
3163
3164 /// Cast an lvalue referring to a derived class to a known base subobject.
CastToBaseClass(EvalInfo & Info,const Expr * E,LValue & Result,const CXXRecordDecl * DerivedRD,const CXXRecordDecl * BaseRD)3165 static bool CastToBaseClass(EvalInfo &Info, const Expr *E, LValue &Result,
3166 const CXXRecordDecl *DerivedRD,
3167 const CXXRecordDecl *BaseRD) {
3168 CXXBasePaths Paths(/*FindAmbiguities=*/false,
3169 /*RecordPaths=*/true, /*DetectVirtual=*/false);
3170 if (!DerivedRD->isDerivedFrom(BaseRD, Paths))
3171 llvm_unreachable("Class must be derived from the passed in base class!");
3172
3173 for (CXXBasePathElement &Elem : Paths.front())
3174 if (!HandleLValueBase(Info, E, Result, Elem.Class, Elem.Base))
3175 return false;
3176 return true;
3177 }
3178
3179 /// Update LVal to refer to the given field, which must be a member of the type
3180 /// currently described by LVal.
HandleLValueMember(EvalInfo & Info,const Expr * E,LValue & LVal,const FieldDecl * FD,const ASTRecordLayout * RL=nullptr)3181 static bool HandleLValueMember(EvalInfo &Info, const Expr *E, LValue &LVal,
3182 const FieldDecl *FD,
3183 const ASTRecordLayout *RL = nullptr) {
3184 if (!RL) {
3185 if (FD->getParent()->isInvalidDecl()) return false;
3186 RL = &Info.Ctx.getASTRecordLayout(FD->getParent());
3187 }
3188
3189 unsigned I = FD->getFieldIndex();
3190 LVal.adjustOffset(Info.Ctx.toCharUnitsFromBits(RL->getFieldOffset(I)));
3191 LVal.addDecl(Info, E, FD);
3192 return true;
3193 }
3194
3195 /// Update LVal to refer to the given indirect field.
HandleLValueIndirectMember(EvalInfo & Info,const Expr * E,LValue & LVal,const IndirectFieldDecl * IFD)3196 static bool HandleLValueIndirectMember(EvalInfo &Info, const Expr *E,
3197 LValue &LVal,
3198 const IndirectFieldDecl *IFD) {
3199 for (const auto *C : IFD->chain())
3200 if (!HandleLValueMember(Info, E, LVal, cast<FieldDecl>(C)))
3201 return false;
3202 return true;
3203 }
3204
3205 enum class SizeOfType {
3206 SizeOf,
3207 DataSizeOf,
3208 };
3209
3210 /// Get the size of the given type in char units.
HandleSizeof(EvalInfo & Info,SourceLocation Loc,QualType Type,CharUnits & Size,SizeOfType SOT=SizeOfType::SizeOf)3211 static bool HandleSizeof(EvalInfo &Info, SourceLocation Loc, QualType Type,
3212 CharUnits &Size, SizeOfType SOT = SizeOfType::SizeOf) {
3213 // sizeof(void), __alignof__(void), sizeof(function) = 1 as a gcc
3214 // extension.
3215 if (Type->isVoidType() || Type->isFunctionType()) {
3216 Size = CharUnits::One();
3217 return true;
3218 }
3219
3220 if (Type->isDependentType()) {
3221 Info.FFDiag(Loc);
3222 return false;
3223 }
3224
3225 if (!Type->isConstantSizeType()) {
3226 // sizeof(vla) is not a constantexpr: C99 6.5.3.4p2.
3227 // FIXME: Better diagnostic.
3228 Info.FFDiag(Loc);
3229 return false;
3230 }
3231
3232 if (SOT == SizeOfType::SizeOf)
3233 Size = Info.Ctx.getTypeSizeInChars(Type);
3234 else
3235 Size = Info.Ctx.getTypeInfoDataSizeInChars(Type).Width;
3236 return true;
3237 }
3238
3239 /// Update a pointer value to model pointer arithmetic.
3240 /// \param Info - Information about the ongoing evaluation.
3241 /// \param E - The expression being evaluated, for diagnostic purposes.
3242 /// \param LVal - The pointer value to be updated.
3243 /// \param EltTy - The pointee type represented by LVal.
3244 /// \param Adjustment - The adjustment, in objects of type EltTy, to add.
HandleLValueArrayAdjustment(EvalInfo & Info,const Expr * E,LValue & LVal,QualType EltTy,APSInt Adjustment)3245 static bool HandleLValueArrayAdjustment(EvalInfo &Info, const Expr *E,
3246 LValue &LVal, QualType EltTy,
3247 APSInt Adjustment) {
3248 CharUnits SizeOfPointee;
3249 if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfPointee))
3250 return false;
3251
3252 LVal.adjustOffsetAndIndex(Info, E, Adjustment, SizeOfPointee);
3253 return true;
3254 }
3255
HandleLValueArrayAdjustment(EvalInfo & Info,const Expr * E,LValue & LVal,QualType EltTy,int64_t Adjustment)3256 static bool HandleLValueArrayAdjustment(EvalInfo &Info, const Expr *E,
3257 LValue &LVal, QualType EltTy,
3258 int64_t Adjustment) {
3259 return HandleLValueArrayAdjustment(Info, E, LVal, EltTy,
3260 APSInt::get(Adjustment));
3261 }
3262
3263 /// Update an lvalue to refer to a component of a complex number.
3264 /// \param Info - Information about the ongoing evaluation.
3265 /// \param LVal - The lvalue to be updated.
3266 /// \param EltTy - The complex number's component type.
3267 /// \param Imag - False for the real component, true for the imaginary.
HandleLValueComplexElement(EvalInfo & Info,const Expr * E,LValue & LVal,QualType EltTy,bool Imag)3268 static bool HandleLValueComplexElement(EvalInfo &Info, const Expr *E,
3269 LValue &LVal, QualType EltTy,
3270 bool Imag) {
3271 if (Imag) {
3272 CharUnits SizeOfComponent;
3273 if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfComponent))
3274 return false;
3275 LVal.Offset += SizeOfComponent;
3276 }
3277 LVal.addComplex(Info, E, EltTy, Imag);
3278 return true;
3279 }
3280
3281 /// Try to evaluate the initializer for a variable declaration.
3282 ///
3283 /// \param Info Information about the ongoing evaluation.
3284 /// \param E An expression to be used when printing diagnostics.
3285 /// \param VD The variable whose initializer should be obtained.
3286 /// \param Version The version of the variable within the frame.
3287 /// \param Frame The frame in which the variable was created. Must be null
3288 /// if this variable is not local to the evaluation.
3289 /// \param Result Filled in with a pointer to the value of the variable.
evaluateVarDeclInit(EvalInfo & Info,const Expr * E,const VarDecl * VD,CallStackFrame * Frame,unsigned Version,APValue * & Result)3290 static bool evaluateVarDeclInit(EvalInfo &Info, const Expr *E,
3291 const VarDecl *VD, CallStackFrame *Frame,
3292 unsigned Version, APValue *&Result) {
3293 APValue::LValueBase Base(VD, Frame ? Frame->Index : 0, Version);
3294
3295 // If this is a local variable, dig out its value.
3296 if (Frame) {
3297 Result = Frame->getTemporary(VD, Version);
3298 if (Result)
3299 return true;
3300
3301 if (!isa<ParmVarDecl>(VD)) {
3302 // Assume variables referenced within a lambda's call operator that were
3303 // not declared within the call operator are captures and during checking
3304 // of a potential constant expression, assume they are unknown constant
3305 // expressions.
3306 assert(isLambdaCallOperator(Frame->Callee) &&
3307 (VD->getDeclContext() != Frame->Callee || VD->isInitCapture()) &&
3308 "missing value for local variable");
3309 if (Info.checkingPotentialConstantExpression())
3310 return false;
3311 // FIXME: This diagnostic is bogus; we do support captures. Is this code
3312 // still reachable at all?
3313 Info.FFDiag(E->getBeginLoc(),
3314 diag::note_unimplemented_constexpr_lambda_feature_ast)
3315 << "captures not currently allowed";
3316 return false;
3317 }
3318 }
3319
3320 // If we're currently evaluating the initializer of this declaration, use that
3321 // in-flight value.
3322 if (Info.EvaluatingDecl == Base) {
3323 Result = Info.EvaluatingDeclValue;
3324 return true;
3325 }
3326
3327 if (isa<ParmVarDecl>(VD)) {
3328 // Assume parameters of a potential constant expression are usable in
3329 // constant expressions.
3330 if (!Info.checkingPotentialConstantExpression() ||
3331 !Info.CurrentCall->Callee ||
3332 !Info.CurrentCall->Callee->Equals(VD->getDeclContext())) {
3333 if (Info.getLangOpts().CPlusPlus11) {
3334 Info.FFDiag(E, diag::note_constexpr_function_param_value_unknown)
3335 << VD;
3336 NoteLValueLocation(Info, Base);
3337 } else {
3338 Info.FFDiag(E);
3339 }
3340 }
3341 return false;
3342 }
3343
3344 if (E->isValueDependent())
3345 return false;
3346
3347 // Dig out the initializer, and use the declaration which it's attached to.
3348 // FIXME: We should eventually check whether the variable has a reachable
3349 // initializing declaration.
3350 const Expr *Init = VD->getAnyInitializer(VD);
3351 if (!Init) {
3352 // Don't diagnose during potential constant expression checking; an
3353 // initializer might be added later.
3354 if (!Info.checkingPotentialConstantExpression()) {
3355 Info.FFDiag(E, diag::note_constexpr_var_init_unknown, 1)
3356 << VD;
3357 NoteLValueLocation(Info, Base);
3358 }
3359 return false;
3360 }
3361
3362 if (Init->isValueDependent()) {
3363 // The DeclRefExpr is not value-dependent, but the variable it refers to
3364 // has a value-dependent initializer. This should only happen in
3365 // constant-folding cases, where the variable is not actually of a suitable
3366 // type for use in a constant expression (otherwise the DeclRefExpr would
3367 // have been value-dependent too), so diagnose that.
3368 assert(!VD->mightBeUsableInConstantExpressions(Info.Ctx));
3369 if (!Info.checkingPotentialConstantExpression()) {
3370 Info.FFDiag(E, Info.getLangOpts().CPlusPlus11
3371 ? diag::note_constexpr_ltor_non_constexpr
3372 : diag::note_constexpr_ltor_non_integral, 1)
3373 << VD << VD->getType();
3374 NoteLValueLocation(Info, Base);
3375 }
3376 return false;
3377 }
3378
3379 // Check that we can fold the initializer. In C++, we will have already done
3380 // this in the cases where it matters for conformance.
3381 if (!VD->evaluateValue()) {
3382 Info.FFDiag(E, diag::note_constexpr_var_init_non_constant, 1) << VD;
3383 NoteLValueLocation(Info, Base);
3384 return false;
3385 }
3386
3387 // Check that the variable is actually usable in constant expressions. For a
3388 // const integral variable or a reference, we might have a non-constant
3389 // initializer that we can nonetheless evaluate the initializer for. Such
3390 // variables are not usable in constant expressions. In C++98, the
3391 // initializer also syntactically needs to be an ICE.
3392 //
3393 // FIXME: We don't diagnose cases that aren't potentially usable in constant
3394 // expressions here; doing so would regress diagnostics for things like
3395 // reading from a volatile constexpr variable.
3396 if ((Info.getLangOpts().CPlusPlus && !VD->hasConstantInitialization() &&
3397 VD->mightBeUsableInConstantExpressions(Info.Ctx)) ||
3398 ((Info.getLangOpts().CPlusPlus || Info.getLangOpts().OpenCL) &&
3399 !Info.getLangOpts().CPlusPlus11 && !VD->hasICEInitializer(Info.Ctx))) {
3400 Info.CCEDiag(E, diag::note_constexpr_var_init_non_constant, 1) << VD;
3401 NoteLValueLocation(Info, Base);
3402 }
3403
3404 // Never use the initializer of a weak variable, not even for constant
3405 // folding. We can't be sure that this is the definition that will be used.
3406 if (VD->isWeak()) {
3407 Info.FFDiag(E, diag::note_constexpr_var_init_weak) << VD;
3408 NoteLValueLocation(Info, Base);
3409 return false;
3410 }
3411
3412 Result = VD->getEvaluatedValue();
3413 return true;
3414 }
3415
3416 /// Get the base index of the given base class within an APValue representing
3417 /// the given derived class.
getBaseIndex(const CXXRecordDecl * Derived,const CXXRecordDecl * Base)3418 static unsigned getBaseIndex(const CXXRecordDecl *Derived,
3419 const CXXRecordDecl *Base) {
3420 Base = Base->getCanonicalDecl();
3421 unsigned Index = 0;
3422 for (CXXRecordDecl::base_class_const_iterator I = Derived->bases_begin(),
3423 E = Derived->bases_end(); I != E; ++I, ++Index) {
3424 if (I->getType()->getAsCXXRecordDecl()->getCanonicalDecl() == Base)
3425 return Index;
3426 }
3427
3428 llvm_unreachable("base class missing from derived class's bases list");
3429 }
3430
3431 /// Extract the value of a character from a string literal.
extractStringLiteralCharacter(EvalInfo & Info,const Expr * Lit,uint64_t Index)3432 static APSInt extractStringLiteralCharacter(EvalInfo &Info, const Expr *Lit,
3433 uint64_t Index) {
3434 assert(!isa<SourceLocExpr>(Lit) &&
3435 "SourceLocExpr should have already been converted to a StringLiteral");
3436
3437 // FIXME: Support MakeStringConstant
3438 if (const auto *ObjCEnc = dyn_cast<ObjCEncodeExpr>(Lit)) {
3439 std::string Str;
3440 Info.Ctx.getObjCEncodingForType(ObjCEnc->getEncodedType(), Str);
3441 assert(Index <= Str.size() && "Index too large");
3442 return APSInt::getUnsigned(Str.c_str()[Index]);
3443 }
3444
3445 if (auto PE = dyn_cast<PredefinedExpr>(Lit))
3446 Lit = PE->getFunctionName();
3447 const StringLiteral *S = cast<StringLiteral>(Lit);
3448 const ConstantArrayType *CAT =
3449 Info.Ctx.getAsConstantArrayType(S->getType());
3450 assert(CAT && "string literal isn't an array");
3451 QualType CharType = CAT->getElementType();
3452 assert(CharType->isIntegerType() && "unexpected character type");
3453 APSInt Value(Info.Ctx.getTypeSize(CharType),
3454 CharType->isUnsignedIntegerType());
3455 if (Index < S->getLength())
3456 Value = S->getCodeUnit(Index);
3457 return Value;
3458 }
3459
3460 // Expand a string literal into an array of characters.
3461 //
3462 // FIXME: This is inefficient; we should probably introduce something similar
3463 // to the LLVM ConstantDataArray to make this cheaper.
expandStringLiteral(EvalInfo & Info,const StringLiteral * S,APValue & Result,QualType AllocType=QualType ())3464 static void expandStringLiteral(EvalInfo &Info, const StringLiteral *S,
3465 APValue &Result,
3466 QualType AllocType = QualType()) {
3467 const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(
3468 AllocType.isNull() ? S->getType() : AllocType);
3469 assert(CAT && "string literal isn't an array");
3470 QualType CharType = CAT->getElementType();
3471 assert(CharType->isIntegerType() && "unexpected character type");
3472
3473 unsigned Elts = CAT->getSize().getZExtValue();
3474 Result = APValue(APValue::UninitArray(),
3475 std::min(S->getLength(), Elts), Elts);
3476 APSInt Value(Info.Ctx.getTypeSize(CharType),
3477 CharType->isUnsignedIntegerType());
3478 if (Result.hasArrayFiller())
3479 Result.getArrayFiller() = APValue(Value);
3480 for (unsigned I = 0, N = Result.getArrayInitializedElts(); I != N; ++I) {
3481 Value = S->getCodeUnit(I);
3482 Result.getArrayInitializedElt(I) = APValue(Value);
3483 }
3484 }
3485
3486 // Expand an array so that it has more than Index filled elements.
expandArray(APValue & Array,unsigned Index)3487 static void expandArray(APValue &Array, unsigned Index) {
3488 unsigned Size = Array.getArraySize();
3489 assert(Index < Size);
3490
3491 // Always at least double the number of elements for which we store a value.
3492 unsigned OldElts = Array.getArrayInitializedElts();
3493 unsigned NewElts = std::max(Index+1, OldElts * 2);
3494 NewElts = std::min(Size, std::max(NewElts, 8u));
3495
3496 // Copy the data across.
3497 APValue NewValue(APValue::UninitArray(), NewElts, Size);
3498 for (unsigned I = 0; I != OldElts; ++I)
3499 NewValue.getArrayInitializedElt(I).swap(Array.getArrayInitializedElt(I));
3500 for (unsigned I = OldElts; I != NewElts; ++I)
3501 NewValue.getArrayInitializedElt(I) = Array.getArrayFiller();
3502 if (NewValue.hasArrayFiller())
3503 NewValue.getArrayFiller() = Array.getArrayFiller();
3504 Array.swap(NewValue);
3505 }
3506
3507 /// Determine whether a type would actually be read by an lvalue-to-rvalue
3508 /// conversion. If it's of class type, we may assume that the copy operation
3509 /// is trivial. Note that this is never true for a union type with fields
3510 /// (because the copy always "reads" the active member) and always true for
3511 /// a non-class type.
3512 static bool isReadByLvalueToRvalueConversion(const CXXRecordDecl *RD);
isReadByLvalueToRvalueConversion(QualType T)3513 static bool isReadByLvalueToRvalueConversion(QualType T) {
3514 CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
3515 return !RD || isReadByLvalueToRvalueConversion(RD);
3516 }
isReadByLvalueToRvalueConversion(const CXXRecordDecl * RD)3517 static bool isReadByLvalueToRvalueConversion(const CXXRecordDecl *RD) {
3518 // FIXME: A trivial copy of a union copies the object representation, even if
3519 // the union is empty.
3520 if (RD->isUnion())
3521 return !RD->field_empty();
3522 if (RD->isEmpty())
3523 return false;
3524
3525 for (auto *Field : RD->fields())
3526 if (!Field->isUnnamedBitfield() &&
3527 isReadByLvalueToRvalueConversion(Field->getType()))
3528 return true;
3529
3530 for (auto &BaseSpec : RD->bases())
3531 if (isReadByLvalueToRvalueConversion(BaseSpec.getType()))
3532 return true;
3533
3534 return false;
3535 }
3536
3537 /// Diagnose an attempt to read from any unreadable field within the specified
3538 /// type, which might be a class type.
diagnoseMutableFields(EvalInfo & Info,const Expr * E,AccessKinds AK,QualType T)3539 static bool diagnoseMutableFields(EvalInfo &Info, const Expr *E, AccessKinds AK,
3540 QualType T) {
3541 CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
3542 if (!RD)
3543 return false;
3544
3545 if (!RD->hasMutableFields())
3546 return false;
3547
3548 for (auto *Field : RD->fields()) {
3549 // If we're actually going to read this field in some way, then it can't
3550 // be mutable. If we're in a union, then assigning to a mutable field
3551 // (even an empty one) can change the active member, so that's not OK.
3552 // FIXME: Add core issue number for the union case.
3553 if (Field->isMutable() &&
3554 (RD->isUnion() || isReadByLvalueToRvalueConversion(Field->getType()))) {
3555 Info.FFDiag(E, diag::note_constexpr_access_mutable, 1) << AK << Field;
3556 Info.Note(Field->getLocation(), diag::note_declared_at);
3557 return true;
3558 }
3559
3560 if (diagnoseMutableFields(Info, E, AK, Field->getType()))
3561 return true;
3562 }
3563
3564 for (auto &BaseSpec : RD->bases())
3565 if (diagnoseMutableFields(Info, E, AK, BaseSpec.getType()))
3566 return true;
3567
3568 // All mutable fields were empty, and thus not actually read.
3569 return false;
3570 }
3571
lifetimeStartedInEvaluation(EvalInfo & Info,APValue::LValueBase Base,bool MutableSubobject=false)3572 static bool lifetimeStartedInEvaluation(EvalInfo &Info,
3573 APValue::LValueBase Base,
3574 bool MutableSubobject = false) {
3575 // A temporary or transient heap allocation we created.
3576 if (Base.getCallIndex() || Base.is<DynamicAllocLValue>())
3577 return true;
3578
3579 switch (Info.IsEvaluatingDecl) {
3580 case EvalInfo::EvaluatingDeclKind::None:
3581 return false;
3582
3583 case EvalInfo::EvaluatingDeclKind::Ctor:
3584 // The variable whose initializer we're evaluating.
3585 if (Info.EvaluatingDecl == Base)
3586 return true;
3587
3588 // A temporary lifetime-extended by the variable whose initializer we're
3589 // evaluating.
3590 if (auto *BaseE = Base.dyn_cast<const Expr *>())
3591 if (auto *BaseMTE = dyn_cast<MaterializeTemporaryExpr>(BaseE))
3592 return Info.EvaluatingDecl == BaseMTE->getExtendingDecl();
3593 return false;
3594
3595 case EvalInfo::EvaluatingDeclKind::Dtor:
3596 // C++2a [expr.const]p6:
3597 // [during constant destruction] the lifetime of a and its non-mutable
3598 // subobjects (but not its mutable subobjects) [are] considered to start
3599 // within e.
3600 if (MutableSubobject || Base != Info.EvaluatingDecl)
3601 return false;
3602 // FIXME: We can meaningfully extend this to cover non-const objects, but
3603 // we will need special handling: we should be able to access only
3604 // subobjects of such objects that are themselves declared const.
3605 QualType T = getType(Base);
3606 return T.isConstQualified() || T->isReferenceType();
3607 }
3608
3609 llvm_unreachable("unknown evaluating decl kind");
3610 }
3611
CheckArraySize(EvalInfo & Info,const ConstantArrayType * CAT,SourceLocation CallLoc={})3612 static bool CheckArraySize(EvalInfo &Info, const ConstantArrayType *CAT,
3613 SourceLocation CallLoc = {}) {
3614 return Info.CheckArraySize(
3615 CAT->getSizeExpr() ? CAT->getSizeExpr()->getBeginLoc() : CallLoc,
3616 CAT->getNumAddressingBits(Info.Ctx), CAT->getSize().getZExtValue(),
3617 /*Diag=*/true);
3618 }
3619
3620 namespace {
3621 /// A handle to a complete object (an object that is not a subobject of
3622 /// another object).
3623 struct CompleteObject {
3624 /// The identity of the object.
3625 APValue::LValueBase Base;
3626 /// The value of the complete object.
3627 APValue *Value;
3628 /// The type of the complete object.
3629 QualType Type;
3630
CompleteObject__anonbf0ddd820a11::CompleteObject3631 CompleteObject() : Value(nullptr) {}
CompleteObject__anonbf0ddd820a11::CompleteObject3632 CompleteObject(APValue::LValueBase Base, APValue *Value, QualType Type)
3633 : Base(Base), Value(Value), Type(Type) {}
3634
mayAccessMutableMembers__anonbf0ddd820a11::CompleteObject3635 bool mayAccessMutableMembers(EvalInfo &Info, AccessKinds AK) const {
3636 // If this isn't a "real" access (eg, if it's just accessing the type
3637 // info), allow it. We assume the type doesn't change dynamically for
3638 // subobjects of constexpr objects (even though we'd hit UB here if it
3639 // did). FIXME: Is this right?
3640 if (!isAnyAccess(AK))
3641 return true;
3642
3643 // In C++14 onwards, it is permitted to read a mutable member whose
3644 // lifetime began within the evaluation.
3645 // FIXME: Should we also allow this in C++11?
3646 if (!Info.getLangOpts().CPlusPlus14)
3647 return false;
3648 return lifetimeStartedInEvaluation(Info, Base, /*MutableSubobject*/true);
3649 }
3650
operator bool__anonbf0ddd820a11::CompleteObject3651 explicit operator bool() const { return !Type.isNull(); }
3652 };
3653 } // end anonymous namespace
3654
getSubobjectType(QualType ObjType,QualType SubobjType,bool IsMutable=false)3655 static QualType getSubobjectType(QualType ObjType, QualType SubobjType,
3656 bool IsMutable = false) {
3657 // C++ [basic.type.qualifier]p1:
3658 // - A const object is an object of type const T or a non-mutable subobject
3659 // of a const object.
3660 if (ObjType.isConstQualified() && !IsMutable)
3661 SubobjType.addConst();
3662 // - A volatile object is an object of type const T or a subobject of a
3663 // volatile object.
3664 if (ObjType.isVolatileQualified())
3665 SubobjType.addVolatile();
3666 return SubobjType;
3667 }
3668
3669 /// Find the designated sub-object of an rvalue.
3670 template<typename SubobjectHandler>
3671 typename SubobjectHandler::result_type
findSubobject(EvalInfo & Info,const Expr * E,const CompleteObject & Obj,const SubobjectDesignator & Sub,SubobjectHandler & handler)3672 findSubobject(EvalInfo &Info, const Expr *E, const CompleteObject &Obj,
3673 const SubobjectDesignator &Sub, SubobjectHandler &handler) {
3674 if (Sub.Invalid)
3675 // A diagnostic will have already been produced.
3676 return handler.failed();
3677 if (Sub.isOnePastTheEnd() || Sub.isMostDerivedAnUnsizedArray()) {
3678 if (Info.getLangOpts().CPlusPlus11)
3679 Info.FFDiag(E, Sub.isOnePastTheEnd()
3680 ? diag::note_constexpr_access_past_end
3681 : diag::note_constexpr_access_unsized_array)
3682 << handler.AccessKind;
3683 else
3684 Info.FFDiag(E);
3685 return handler.failed();
3686 }
3687
3688 APValue *O = Obj.Value;
3689 QualType ObjType = Obj.Type;
3690 const FieldDecl *LastField = nullptr;
3691 const FieldDecl *VolatileField = nullptr;
3692
3693 // Walk the designator's path to find the subobject.
3694 for (unsigned I = 0, N = Sub.Entries.size(); /**/; ++I) {
3695 // Reading an indeterminate value is undefined, but assigning over one is OK.
3696 if ((O->isAbsent() && !(handler.AccessKind == AK_Construct && I == N)) ||
3697 (O->isIndeterminate() &&
3698 !isValidIndeterminateAccess(handler.AccessKind))) {
3699 if (!Info.checkingPotentialConstantExpression())
3700 Info.FFDiag(E, diag::note_constexpr_access_uninit)
3701 << handler.AccessKind << O->isIndeterminate()
3702 << E->getSourceRange();
3703 return handler.failed();
3704 }
3705
3706 // C++ [class.ctor]p5, C++ [class.dtor]p5:
3707 // const and volatile semantics are not applied on an object under
3708 // {con,de}struction.
3709 if ((ObjType.isConstQualified() || ObjType.isVolatileQualified()) &&
3710 ObjType->isRecordType() &&
3711 Info.isEvaluatingCtorDtor(
3712 Obj.Base,
3713 llvm::ArrayRef(Sub.Entries.begin(), Sub.Entries.begin() + I)) !=
3714 ConstructionPhase::None) {
3715 ObjType = Info.Ctx.getCanonicalType(ObjType);
3716 ObjType.removeLocalConst();
3717 ObjType.removeLocalVolatile();
3718 }
3719
3720 // If this is our last pass, check that the final object type is OK.
3721 if (I == N || (I == N - 1 && ObjType->isAnyComplexType())) {
3722 // Accesses to volatile objects are prohibited.
3723 if (ObjType.isVolatileQualified() && isFormalAccess(handler.AccessKind)) {
3724 if (Info.getLangOpts().CPlusPlus) {
3725 int DiagKind;
3726 SourceLocation Loc;
3727 const NamedDecl *Decl = nullptr;
3728 if (VolatileField) {
3729 DiagKind = 2;
3730 Loc = VolatileField->getLocation();
3731 Decl = VolatileField;
3732 } else if (auto *VD = Obj.Base.dyn_cast<const ValueDecl*>()) {
3733 DiagKind = 1;
3734 Loc = VD->getLocation();
3735 Decl = VD;
3736 } else {
3737 DiagKind = 0;
3738 if (auto *E = Obj.Base.dyn_cast<const Expr *>())
3739 Loc = E->getExprLoc();
3740 }
3741 Info.FFDiag(E, diag::note_constexpr_access_volatile_obj, 1)
3742 << handler.AccessKind << DiagKind << Decl;
3743 Info.Note(Loc, diag::note_constexpr_volatile_here) << DiagKind;
3744 } else {
3745 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
3746 }
3747 return handler.failed();
3748 }
3749
3750 // If we are reading an object of class type, there may still be more
3751 // things we need to check: if there are any mutable subobjects, we
3752 // cannot perform this read. (This only happens when performing a trivial
3753 // copy or assignment.)
3754 if (ObjType->isRecordType() &&
3755 !Obj.mayAccessMutableMembers(Info, handler.AccessKind) &&
3756 diagnoseMutableFields(Info, E, handler.AccessKind, ObjType))
3757 return handler.failed();
3758 }
3759
3760 if (I == N) {
3761 if (!handler.found(*O, ObjType))
3762 return false;
3763
3764 // If we modified a bit-field, truncate it to the right width.
3765 if (isModification(handler.AccessKind) &&
3766 LastField && LastField->isBitField() &&
3767 !truncateBitfieldValue(Info, E, *O, LastField))
3768 return false;
3769
3770 return true;
3771 }
3772
3773 LastField = nullptr;
3774 if (ObjType->isArrayType()) {
3775 // Next subobject is an array element.
3776 const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(ObjType);
3777 assert(CAT && "vla in literal type?");
3778 uint64_t Index = Sub.Entries[I].getAsArrayIndex();
3779 if (CAT->getSize().ule(Index)) {
3780 // Note, it should not be possible to form a pointer with a valid
3781 // designator which points more than one past the end of the array.
3782 if (Info.getLangOpts().CPlusPlus11)
3783 Info.FFDiag(E, diag::note_constexpr_access_past_end)
3784 << handler.AccessKind;
3785 else
3786 Info.FFDiag(E);
3787 return handler.failed();
3788 }
3789
3790 ObjType = CAT->getElementType();
3791
3792 if (O->getArrayInitializedElts() > Index)
3793 O = &O->getArrayInitializedElt(Index);
3794 else if (!isRead(handler.AccessKind)) {
3795 if (!CheckArraySize(Info, CAT, E->getExprLoc()))
3796 return handler.failed();
3797
3798 expandArray(*O, Index);
3799 O = &O->getArrayInitializedElt(Index);
3800 } else
3801 O = &O->getArrayFiller();
3802 } else if (ObjType->isAnyComplexType()) {
3803 // Next subobject is a complex number.
3804 uint64_t Index = Sub.Entries[I].getAsArrayIndex();
3805 if (Index > 1) {
3806 if (Info.getLangOpts().CPlusPlus11)
3807 Info.FFDiag(E, diag::note_constexpr_access_past_end)
3808 << handler.AccessKind;
3809 else
3810 Info.FFDiag(E);
3811 return handler.failed();
3812 }
3813
3814 ObjType = getSubobjectType(
3815 ObjType, ObjType->castAs<ComplexType>()->getElementType());
3816
3817 assert(I == N - 1 && "extracting subobject of scalar?");
3818 if (O->isComplexInt()) {
3819 return handler.found(Index ? O->getComplexIntImag()
3820 : O->getComplexIntReal(), ObjType);
3821 } else {
3822 assert(O->isComplexFloat());
3823 return handler.found(Index ? O->getComplexFloatImag()
3824 : O->getComplexFloatReal(), ObjType);
3825 }
3826 } else if (const FieldDecl *Field = getAsField(Sub.Entries[I])) {
3827 if (Field->isMutable() &&
3828 !Obj.mayAccessMutableMembers(Info, handler.AccessKind)) {
3829 Info.FFDiag(E, diag::note_constexpr_access_mutable, 1)
3830 << handler.AccessKind << Field;
3831 Info.Note(Field->getLocation(), diag::note_declared_at);
3832 return handler.failed();
3833 }
3834
3835 // Next subobject is a class, struct or union field.
3836 RecordDecl *RD = ObjType->castAs<RecordType>()->getDecl();
3837 if (RD->isUnion()) {
3838 const FieldDecl *UnionField = O->getUnionField();
3839 if (!UnionField ||
3840 UnionField->getCanonicalDecl() != Field->getCanonicalDecl()) {
3841 if (I == N - 1 && handler.AccessKind == AK_Construct) {
3842 // Placement new onto an inactive union member makes it active.
3843 O->setUnion(Field, APValue());
3844 } else {
3845 // FIXME: If O->getUnionValue() is absent, report that there's no
3846 // active union member rather than reporting the prior active union
3847 // member. We'll need to fix nullptr_t to not use APValue() as its
3848 // representation first.
3849 Info.FFDiag(E, diag::note_constexpr_access_inactive_union_member)
3850 << handler.AccessKind << Field << !UnionField << UnionField;
3851 return handler.failed();
3852 }
3853 }
3854 O = &O->getUnionValue();
3855 } else
3856 O = &O->getStructField(Field->getFieldIndex());
3857
3858 ObjType = getSubobjectType(ObjType, Field->getType(), Field->isMutable());
3859 LastField = Field;
3860 if (Field->getType().isVolatileQualified())
3861 VolatileField = Field;
3862 } else {
3863 // Next subobject is a base class.
3864 const CXXRecordDecl *Derived = ObjType->getAsCXXRecordDecl();
3865 const CXXRecordDecl *Base = getAsBaseClass(Sub.Entries[I]);
3866 O = &O->getStructBase(getBaseIndex(Derived, Base));
3867
3868 ObjType = getSubobjectType(ObjType, Info.Ctx.getRecordType(Base));
3869 }
3870 }
3871 }
3872
3873 namespace {
3874 struct ExtractSubobjectHandler {
3875 EvalInfo &Info;
3876 const Expr *E;
3877 APValue &Result;
3878 const AccessKinds AccessKind;
3879
3880 typedef bool result_type;
failed__anonbf0ddd820b11::ExtractSubobjectHandler3881 bool failed() { return false; }
found__anonbf0ddd820b11::ExtractSubobjectHandler3882 bool found(APValue &Subobj, QualType SubobjType) {
3883 Result = Subobj;
3884 if (AccessKind == AK_ReadObjectRepresentation)
3885 return true;
3886 return CheckFullyInitialized(Info, E->getExprLoc(), SubobjType, Result);
3887 }
found__anonbf0ddd820b11::ExtractSubobjectHandler3888 bool found(APSInt &Value, QualType SubobjType) {
3889 Result = APValue(Value);
3890 return true;
3891 }
found__anonbf0ddd820b11::ExtractSubobjectHandler3892 bool found(APFloat &Value, QualType SubobjType) {
3893 Result = APValue(Value);
3894 return true;
3895 }
3896 };
3897 } // end anonymous namespace
3898
3899 /// Extract the designated sub-object of an rvalue.
extractSubobject(EvalInfo & Info,const Expr * E,const CompleteObject & Obj,const SubobjectDesignator & Sub,APValue & Result,AccessKinds AK=AK_Read)3900 static bool extractSubobject(EvalInfo &Info, const Expr *E,
3901 const CompleteObject &Obj,
3902 const SubobjectDesignator &Sub, APValue &Result,
3903 AccessKinds AK = AK_Read) {
3904 assert(AK == AK_Read || AK == AK_ReadObjectRepresentation);
3905 ExtractSubobjectHandler Handler = {Info, E, Result, AK};
3906 return findSubobject(Info, E, Obj, Sub, Handler);
3907 }
3908
3909 namespace {
3910 struct ModifySubobjectHandler {
3911 EvalInfo &Info;
3912 APValue &NewVal;
3913 const Expr *E;
3914
3915 typedef bool result_type;
3916 static const AccessKinds AccessKind = AK_Assign;
3917
checkConst__anonbf0ddd820c11::ModifySubobjectHandler3918 bool checkConst(QualType QT) {
3919 // Assigning to a const object has undefined behavior.
3920 if (QT.isConstQualified()) {
3921 Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT;
3922 return false;
3923 }
3924 return true;
3925 }
3926
failed__anonbf0ddd820c11::ModifySubobjectHandler3927 bool failed() { return false; }
found__anonbf0ddd820c11::ModifySubobjectHandler3928 bool found(APValue &Subobj, QualType SubobjType) {
3929 if (!checkConst(SubobjType))
3930 return false;
3931 // We've been given ownership of NewVal, so just swap it in.
3932 Subobj.swap(NewVal);
3933 return true;
3934 }
found__anonbf0ddd820c11::ModifySubobjectHandler3935 bool found(APSInt &Value, QualType SubobjType) {
3936 if (!checkConst(SubobjType))
3937 return false;
3938 if (!NewVal.isInt()) {
3939 // Maybe trying to write a cast pointer value into a complex?
3940 Info.FFDiag(E);
3941 return false;
3942 }
3943 Value = NewVal.getInt();
3944 return true;
3945 }
found__anonbf0ddd820c11::ModifySubobjectHandler3946 bool found(APFloat &Value, QualType SubobjType) {
3947 if (!checkConst(SubobjType))
3948 return false;
3949 Value = NewVal.getFloat();
3950 return true;
3951 }
3952 };
3953 } // end anonymous namespace
3954
3955 const AccessKinds ModifySubobjectHandler::AccessKind;
3956
3957 /// Update the designated sub-object of an rvalue to the given value.
modifySubobject(EvalInfo & Info,const Expr * E,const CompleteObject & Obj,const SubobjectDesignator & Sub,APValue & NewVal)3958 static bool modifySubobject(EvalInfo &Info, const Expr *E,
3959 const CompleteObject &Obj,
3960 const SubobjectDesignator &Sub,
3961 APValue &NewVal) {
3962 ModifySubobjectHandler Handler = { Info, NewVal, E };
3963 return findSubobject(Info, E, Obj, Sub, Handler);
3964 }
3965
3966 /// Find the position where two subobject designators diverge, or equivalently
3967 /// the length of the common initial subsequence.
FindDesignatorMismatch(QualType ObjType,const SubobjectDesignator & A,const SubobjectDesignator & B,bool & WasArrayIndex)3968 static unsigned FindDesignatorMismatch(QualType ObjType,
3969 const SubobjectDesignator &A,
3970 const SubobjectDesignator &B,
3971 bool &WasArrayIndex) {
3972 unsigned I = 0, N = std::min(A.Entries.size(), B.Entries.size());
3973 for (/**/; I != N; ++I) {
3974 if (!ObjType.isNull() &&
3975 (ObjType->isArrayType() || ObjType->isAnyComplexType())) {
3976 // Next subobject is an array element.
3977 if (A.Entries[I].getAsArrayIndex() != B.Entries[I].getAsArrayIndex()) {
3978 WasArrayIndex = true;
3979 return I;
3980 }
3981 if (ObjType->isAnyComplexType())
3982 ObjType = ObjType->castAs<ComplexType>()->getElementType();
3983 else
3984 ObjType = ObjType->castAsArrayTypeUnsafe()->getElementType();
3985 } else {
3986 if (A.Entries[I].getAsBaseOrMember() !=
3987 B.Entries[I].getAsBaseOrMember()) {
3988 WasArrayIndex = false;
3989 return I;
3990 }
3991 if (const FieldDecl *FD = getAsField(A.Entries[I]))
3992 // Next subobject is a field.
3993 ObjType = FD->getType();
3994 else
3995 // Next subobject is a base class.
3996 ObjType = QualType();
3997 }
3998 }
3999 WasArrayIndex = false;
4000 return I;
4001 }
4002
4003 /// Determine whether the given subobject designators refer to elements of the
4004 /// same array object.
AreElementsOfSameArray(QualType ObjType,const SubobjectDesignator & A,const SubobjectDesignator & B)4005 static bool AreElementsOfSameArray(QualType ObjType,
4006 const SubobjectDesignator &A,
4007 const SubobjectDesignator &B) {
4008 if (A.Entries.size() != B.Entries.size())
4009 return false;
4010
4011 bool IsArray = A.MostDerivedIsArrayElement;
4012 if (IsArray && A.MostDerivedPathLength != A.Entries.size())
4013 // A is a subobject of the array element.
4014 return false;
4015
4016 // If A (and B) designates an array element, the last entry will be the array
4017 // index. That doesn't have to match. Otherwise, we're in the 'implicit array
4018 // of length 1' case, and the entire path must match.
4019 bool WasArrayIndex;
4020 unsigned CommonLength = FindDesignatorMismatch(ObjType, A, B, WasArrayIndex);
4021 return CommonLength >= A.Entries.size() - IsArray;
4022 }
4023
4024 /// Find the complete object to which an LValue refers.
findCompleteObject(EvalInfo & Info,const Expr * E,AccessKinds AK,const LValue & LVal,QualType LValType)4025 static CompleteObject findCompleteObject(EvalInfo &Info, const Expr *E,
4026 AccessKinds AK, const LValue &LVal,
4027 QualType LValType) {
4028 if (LVal.InvalidBase) {
4029 Info.FFDiag(E);
4030 return CompleteObject();
4031 }
4032
4033 if (!LVal.Base) {
4034 Info.FFDiag(E, diag::note_constexpr_access_null) << AK;
4035 return CompleteObject();
4036 }
4037
4038 CallStackFrame *Frame = nullptr;
4039 unsigned Depth = 0;
4040 if (LVal.getLValueCallIndex()) {
4041 std::tie(Frame, Depth) =
4042 Info.getCallFrameAndDepth(LVal.getLValueCallIndex());
4043 if (!Frame) {
4044 Info.FFDiag(E, diag::note_constexpr_lifetime_ended, 1)
4045 << AK << LVal.Base.is<const ValueDecl*>();
4046 NoteLValueLocation(Info, LVal.Base);
4047 return CompleteObject();
4048 }
4049 }
4050
4051 bool IsAccess = isAnyAccess(AK);
4052
4053 // C++11 DR1311: An lvalue-to-rvalue conversion on a volatile-qualified type
4054 // is not a constant expression (even if the object is non-volatile). We also
4055 // apply this rule to C++98, in order to conform to the expected 'volatile'
4056 // semantics.
4057 if (isFormalAccess(AK) && LValType.isVolatileQualified()) {
4058 if (Info.getLangOpts().CPlusPlus)
4059 Info.FFDiag(E, diag::note_constexpr_access_volatile_type)
4060 << AK << LValType;
4061 else
4062 Info.FFDiag(E);
4063 return CompleteObject();
4064 }
4065
4066 // Compute value storage location and type of base object.
4067 APValue *BaseVal = nullptr;
4068 QualType BaseType = getType(LVal.Base);
4069
4070 if (Info.getLangOpts().CPlusPlus14 && LVal.Base == Info.EvaluatingDecl &&
4071 lifetimeStartedInEvaluation(Info, LVal.Base)) {
4072 // This is the object whose initializer we're evaluating, so its lifetime
4073 // started in the current evaluation.
4074 BaseVal = Info.EvaluatingDeclValue;
4075 } else if (const ValueDecl *D = LVal.Base.dyn_cast<const ValueDecl *>()) {
4076 // Allow reading from a GUID declaration.
4077 if (auto *GD = dyn_cast<MSGuidDecl>(D)) {
4078 if (isModification(AK)) {
4079 // All the remaining cases do not permit modification of the object.
4080 Info.FFDiag(E, diag::note_constexpr_modify_global);
4081 return CompleteObject();
4082 }
4083 APValue &V = GD->getAsAPValue();
4084 if (V.isAbsent()) {
4085 Info.FFDiag(E, diag::note_constexpr_unsupported_layout)
4086 << GD->getType();
4087 return CompleteObject();
4088 }
4089 return CompleteObject(LVal.Base, &V, GD->getType());
4090 }
4091
4092 // Allow reading the APValue from an UnnamedGlobalConstantDecl.
4093 if (auto *GCD = dyn_cast<UnnamedGlobalConstantDecl>(D)) {
4094 if (isModification(AK)) {
4095 Info.FFDiag(E, diag::note_constexpr_modify_global);
4096 return CompleteObject();
4097 }
4098 return CompleteObject(LVal.Base, const_cast<APValue *>(&GCD->getValue()),
4099 GCD->getType());
4100 }
4101
4102 // Allow reading from template parameter objects.
4103 if (auto *TPO = dyn_cast<TemplateParamObjectDecl>(D)) {
4104 if (isModification(AK)) {
4105 Info.FFDiag(E, diag::note_constexpr_modify_global);
4106 return CompleteObject();
4107 }
4108 return CompleteObject(LVal.Base, const_cast<APValue *>(&TPO->getValue()),
4109 TPO->getType());
4110 }
4111
4112 // In C++98, const, non-volatile integers initialized with ICEs are ICEs.
4113 // In C++11, constexpr, non-volatile variables initialized with constant
4114 // expressions are constant expressions too. Inside constexpr functions,
4115 // parameters are constant expressions even if they're non-const.
4116 // In C++1y, objects local to a constant expression (those with a Frame) are
4117 // both readable and writable inside constant expressions.
4118 // In C, such things can also be folded, although they are not ICEs.
4119 const VarDecl *VD = dyn_cast<VarDecl>(D);
4120 if (VD) {
4121 if (const VarDecl *VDef = VD->getDefinition(Info.Ctx))
4122 VD = VDef;
4123 }
4124 if (!VD || VD->isInvalidDecl()) {
4125 Info.FFDiag(E);
4126 return CompleteObject();
4127 }
4128
4129 bool IsConstant = BaseType.isConstant(Info.Ctx);
4130
4131 // Unless we're looking at a local variable or argument in a constexpr call,
4132 // the variable we're reading must be const.
4133 if (!Frame) {
4134 if (IsAccess && isa<ParmVarDecl>(VD)) {
4135 // Access of a parameter that's not associated with a frame isn't going
4136 // to work out, but we can leave it to evaluateVarDeclInit to provide a
4137 // suitable diagnostic.
4138 } else if (Info.getLangOpts().CPlusPlus14 &&
4139 lifetimeStartedInEvaluation(Info, LVal.Base)) {
4140 // OK, we can read and modify an object if we're in the process of
4141 // evaluating its initializer, because its lifetime began in this
4142 // evaluation.
4143 } else if (isModification(AK)) {
4144 // All the remaining cases do not permit modification of the object.
4145 Info.FFDiag(E, diag::note_constexpr_modify_global);
4146 return CompleteObject();
4147 } else if (VD->isConstexpr()) {
4148 // OK, we can read this variable.
4149 } else if (BaseType->isIntegralOrEnumerationType()) {
4150 if (!IsConstant) {
4151 if (!IsAccess)
4152 return CompleteObject(LVal.getLValueBase(), nullptr, BaseType);
4153 if (Info.getLangOpts().CPlusPlus) {
4154 Info.FFDiag(E, diag::note_constexpr_ltor_non_const_int, 1) << VD;
4155 Info.Note(VD->getLocation(), diag::note_declared_at);
4156 } else {
4157 Info.FFDiag(E);
4158 }
4159 return CompleteObject();
4160 }
4161 } else if (!IsAccess) {
4162 return CompleteObject(LVal.getLValueBase(), nullptr, BaseType);
4163 } else if (IsConstant && Info.checkingPotentialConstantExpression() &&
4164 BaseType->isLiteralType(Info.Ctx) && !VD->hasDefinition()) {
4165 // This variable might end up being constexpr. Don't diagnose it yet.
4166 } else if (IsConstant) {
4167 // Keep evaluating to see what we can do. In particular, we support
4168 // folding of const floating-point types, in order to make static const
4169 // data members of such types (supported as an extension) more useful.
4170 if (Info.getLangOpts().CPlusPlus) {
4171 Info.CCEDiag(E, Info.getLangOpts().CPlusPlus11
4172 ? diag::note_constexpr_ltor_non_constexpr
4173 : diag::note_constexpr_ltor_non_integral, 1)
4174 << VD << BaseType;
4175 Info.Note(VD->getLocation(), diag::note_declared_at);
4176 } else {
4177 Info.CCEDiag(E);
4178 }
4179 } else {
4180 // Never allow reading a non-const value.
4181 if (Info.getLangOpts().CPlusPlus) {
4182 Info.FFDiag(E, Info.getLangOpts().CPlusPlus11
4183 ? diag::note_constexpr_ltor_non_constexpr
4184 : diag::note_constexpr_ltor_non_integral, 1)
4185 << VD << BaseType;
4186 Info.Note(VD->getLocation(), diag::note_declared_at);
4187 } else {
4188 Info.FFDiag(E);
4189 }
4190 return CompleteObject();
4191 }
4192 }
4193
4194 if (!evaluateVarDeclInit(Info, E, VD, Frame, LVal.getLValueVersion(), BaseVal))
4195 return CompleteObject();
4196 } else if (DynamicAllocLValue DA = LVal.Base.dyn_cast<DynamicAllocLValue>()) {
4197 std::optional<DynAlloc *> Alloc = Info.lookupDynamicAlloc(DA);
4198 if (!Alloc) {
4199 Info.FFDiag(E, diag::note_constexpr_access_deleted_object) << AK;
4200 return CompleteObject();
4201 }
4202 return CompleteObject(LVal.Base, &(*Alloc)->Value,
4203 LVal.Base.getDynamicAllocType());
4204 } else {
4205 const Expr *Base = LVal.Base.dyn_cast<const Expr*>();
4206
4207 if (!Frame) {
4208 if (const MaterializeTemporaryExpr *MTE =
4209 dyn_cast_or_null<MaterializeTemporaryExpr>(Base)) {
4210 assert(MTE->getStorageDuration() == SD_Static &&
4211 "should have a frame for a non-global materialized temporary");
4212
4213 // C++20 [expr.const]p4: [DR2126]
4214 // An object or reference is usable in constant expressions if it is
4215 // - a temporary object of non-volatile const-qualified literal type
4216 // whose lifetime is extended to that of a variable that is usable
4217 // in constant expressions
4218 //
4219 // C++20 [expr.const]p5:
4220 // an lvalue-to-rvalue conversion [is not allowed unless it applies to]
4221 // - a non-volatile glvalue that refers to an object that is usable
4222 // in constant expressions, or
4223 // - a non-volatile glvalue of literal type that refers to a
4224 // non-volatile object whose lifetime began within the evaluation
4225 // of E;
4226 //
4227 // C++11 misses the 'began within the evaluation of e' check and
4228 // instead allows all temporaries, including things like:
4229 // int &&r = 1;
4230 // int x = ++r;
4231 // constexpr int k = r;
4232 // Therefore we use the C++14-onwards rules in C++11 too.
4233 //
4234 // Note that temporaries whose lifetimes began while evaluating a
4235 // variable's constructor are not usable while evaluating the
4236 // corresponding destructor, not even if they're of const-qualified
4237 // types.
4238 if (!MTE->isUsableInConstantExpressions(Info.Ctx) &&
4239 !lifetimeStartedInEvaluation(Info, LVal.Base)) {
4240 if (!IsAccess)
4241 return CompleteObject(LVal.getLValueBase(), nullptr, BaseType);
4242 Info.FFDiag(E, diag::note_constexpr_access_static_temporary, 1) << AK;
4243 Info.Note(MTE->getExprLoc(), diag::note_constexpr_temporary_here);
4244 return CompleteObject();
4245 }
4246
4247 BaseVal = MTE->getOrCreateValue(false);
4248 assert(BaseVal && "got reference to unevaluated temporary");
4249 } else {
4250 if (!IsAccess)
4251 return CompleteObject(LVal.getLValueBase(), nullptr, BaseType);
4252 APValue Val;
4253 LVal.moveInto(Val);
4254 Info.FFDiag(E, diag::note_constexpr_access_unreadable_object)
4255 << AK
4256 << Val.getAsString(Info.Ctx,
4257 Info.Ctx.getLValueReferenceType(LValType));
4258 NoteLValueLocation(Info, LVal.Base);
4259 return CompleteObject();
4260 }
4261 } else {
4262 BaseVal = Frame->getTemporary(Base, LVal.Base.getVersion());
4263 assert(BaseVal && "missing value for temporary");
4264 }
4265 }
4266
4267 // In C++14, we can't safely access any mutable state when we might be
4268 // evaluating after an unmodeled side effect. Parameters are modeled as state
4269 // in the caller, but aren't visible once the call returns, so they can be
4270 // modified in a speculatively-evaluated call.
4271 //
4272 // FIXME: Not all local state is mutable. Allow local constant subobjects
4273 // to be read here (but take care with 'mutable' fields).
4274 unsigned VisibleDepth = Depth;
4275 if (llvm::isa_and_nonnull<ParmVarDecl>(
4276 LVal.Base.dyn_cast<const ValueDecl *>()))
4277 ++VisibleDepth;
4278 if ((Frame && Info.getLangOpts().CPlusPlus14 &&
4279 Info.EvalStatus.HasSideEffects) ||
4280 (isModification(AK) && VisibleDepth < Info.SpeculativeEvaluationDepth))
4281 return CompleteObject();
4282
4283 return CompleteObject(LVal.getLValueBase(), BaseVal, BaseType);
4284 }
4285
4286 /// Perform an lvalue-to-rvalue conversion on the given glvalue. This
4287 /// can also be used for 'lvalue-to-lvalue' conversions for looking up the
4288 /// glvalue referred to by an entity of reference type.
4289 ///
4290 /// \param Info - Information about the ongoing evaluation.
4291 /// \param Conv - The expression for which we are performing the conversion.
4292 /// Used for diagnostics.
4293 /// \param Type - The type of the glvalue (before stripping cv-qualifiers in the
4294 /// case of a non-class type).
4295 /// \param LVal - The glvalue on which we are attempting to perform this action.
4296 /// \param RVal - The produced value will be placed here.
4297 /// \param WantObjectRepresentation - If true, we're looking for the object
4298 /// representation rather than the value, and in particular,
4299 /// there is no requirement that the result be fully initialized.
4300 static bool
handleLValueToRValueConversion(EvalInfo & Info,const Expr * Conv,QualType Type,const LValue & LVal,APValue & RVal,bool WantObjectRepresentation=false)4301 handleLValueToRValueConversion(EvalInfo &Info, const Expr *Conv, QualType Type,
4302 const LValue &LVal, APValue &RVal,
4303 bool WantObjectRepresentation = false) {
4304 if (LVal.Designator.Invalid)
4305 return false;
4306
4307 // Check for special cases where there is no existing APValue to look at.
4308 const Expr *Base = LVal.Base.dyn_cast<const Expr*>();
4309
4310 AccessKinds AK =
4311 WantObjectRepresentation ? AK_ReadObjectRepresentation : AK_Read;
4312
4313 if (Base && !LVal.getLValueCallIndex() && !Type.isVolatileQualified()) {
4314 if (const CompoundLiteralExpr *CLE = dyn_cast<CompoundLiteralExpr>(Base)) {
4315 // In C99, a CompoundLiteralExpr is an lvalue, and we defer evaluating the
4316 // initializer until now for such expressions. Such an expression can't be
4317 // an ICE in C, so this only matters for fold.
4318 if (Type.isVolatileQualified()) {
4319 Info.FFDiag(Conv);
4320 return false;
4321 }
4322
4323 APValue Lit;
4324 if (!Evaluate(Lit, Info, CLE->getInitializer()))
4325 return false;
4326
4327 // According to GCC info page:
4328 //
4329 // 6.28 Compound Literals
4330 //
4331 // As an optimization, G++ sometimes gives array compound literals longer
4332 // lifetimes: when the array either appears outside a function or has a
4333 // const-qualified type. If foo and its initializer had elements of type
4334 // char *const rather than char *, or if foo were a global variable, the
4335 // array would have static storage duration. But it is probably safest
4336 // just to avoid the use of array compound literals in C++ code.
4337 //
4338 // Obey that rule by checking constness for converted array types.
4339
4340 QualType CLETy = CLE->getType();
4341 if (CLETy->isArrayType() && !Type->isArrayType()) {
4342 if (!CLETy.isConstant(Info.Ctx)) {
4343 Info.FFDiag(Conv);
4344 Info.Note(CLE->getExprLoc(), diag::note_declared_at);
4345 return false;
4346 }
4347 }
4348
4349 CompleteObject LitObj(LVal.Base, &Lit, Base->getType());
4350 return extractSubobject(Info, Conv, LitObj, LVal.Designator, RVal, AK);
4351 } else if (isa<StringLiteral>(Base) || isa<PredefinedExpr>(Base)) {
4352 // Special-case character extraction so we don't have to construct an
4353 // APValue for the whole string.
4354 assert(LVal.Designator.Entries.size() <= 1 &&
4355 "Can only read characters from string literals");
4356 if (LVal.Designator.Entries.empty()) {
4357 // Fail for now for LValue to RValue conversion of an array.
4358 // (This shouldn't show up in C/C++, but it could be triggered by a
4359 // weird EvaluateAsRValue call from a tool.)
4360 Info.FFDiag(Conv);
4361 return false;
4362 }
4363 if (LVal.Designator.isOnePastTheEnd()) {
4364 if (Info.getLangOpts().CPlusPlus11)
4365 Info.FFDiag(Conv, diag::note_constexpr_access_past_end) << AK;
4366 else
4367 Info.FFDiag(Conv);
4368 return false;
4369 }
4370 uint64_t CharIndex = LVal.Designator.Entries[0].getAsArrayIndex();
4371 RVal = APValue(extractStringLiteralCharacter(Info, Base, CharIndex));
4372 return true;
4373 }
4374 }
4375
4376 CompleteObject Obj = findCompleteObject(Info, Conv, AK, LVal, Type);
4377 return Obj && extractSubobject(Info, Conv, Obj, LVal.Designator, RVal, AK);
4378 }
4379
4380 /// Perform an assignment of Val to LVal. Takes ownership of Val.
handleAssignment(EvalInfo & Info,const Expr * E,const LValue & LVal,QualType LValType,APValue & Val)4381 static bool handleAssignment(EvalInfo &Info, const Expr *E, const LValue &LVal,
4382 QualType LValType, APValue &Val) {
4383 if (LVal.Designator.Invalid)
4384 return false;
4385
4386 if (!Info.getLangOpts().CPlusPlus14) {
4387 Info.FFDiag(E);
4388 return false;
4389 }
4390
4391 CompleteObject Obj = findCompleteObject(Info, E, AK_Assign, LVal, LValType);
4392 return Obj && modifySubobject(Info, E, Obj, LVal.Designator, Val);
4393 }
4394
4395 namespace {
4396 struct CompoundAssignSubobjectHandler {
4397 EvalInfo &Info;
4398 const CompoundAssignOperator *E;
4399 QualType PromotedLHSType;
4400 BinaryOperatorKind Opcode;
4401 const APValue &RHS;
4402
4403 static const AccessKinds AccessKind = AK_Assign;
4404
4405 typedef bool result_type;
4406
checkConst__anonbf0ddd820d11::CompoundAssignSubobjectHandler4407 bool checkConst(QualType QT) {
4408 // Assigning to a const object has undefined behavior.
4409 if (QT.isConstQualified()) {
4410 Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT;
4411 return false;
4412 }
4413 return true;
4414 }
4415
failed__anonbf0ddd820d11::CompoundAssignSubobjectHandler4416 bool failed() { return false; }
found__anonbf0ddd820d11::CompoundAssignSubobjectHandler4417 bool found(APValue &Subobj, QualType SubobjType) {
4418 switch (Subobj.getKind()) {
4419 case APValue::Int:
4420 return found(Subobj.getInt(), SubobjType);
4421 case APValue::Float:
4422 return found(Subobj.getFloat(), SubobjType);
4423 case APValue::ComplexInt:
4424 case APValue::ComplexFloat:
4425 // FIXME: Implement complex compound assignment.
4426 Info.FFDiag(E);
4427 return false;
4428 case APValue::LValue:
4429 return foundPointer(Subobj, SubobjType);
4430 case APValue::Vector:
4431 return foundVector(Subobj, SubobjType);
4432 case APValue::Indeterminate:
4433 Info.FFDiag(E, diag::note_constexpr_access_uninit)
4434 << /*read of=*/0 << /*uninitialized object=*/1
4435 << E->getLHS()->getSourceRange();
4436 return false;
4437 default:
4438 // FIXME: can this happen?
4439 Info.FFDiag(E);
4440 return false;
4441 }
4442 }
4443
foundVector__anonbf0ddd820d11::CompoundAssignSubobjectHandler4444 bool foundVector(APValue &Value, QualType SubobjType) {
4445 if (!checkConst(SubobjType))
4446 return false;
4447
4448 if (!SubobjType->isVectorType()) {
4449 Info.FFDiag(E);
4450 return false;
4451 }
4452 return handleVectorVectorBinOp(Info, E, Opcode, Value, RHS);
4453 }
4454
found__anonbf0ddd820d11::CompoundAssignSubobjectHandler4455 bool found(APSInt &Value, QualType SubobjType) {
4456 if (!checkConst(SubobjType))
4457 return false;
4458
4459 if (!SubobjType->isIntegerType()) {
4460 // We don't support compound assignment on integer-cast-to-pointer
4461 // values.
4462 Info.FFDiag(E);
4463 return false;
4464 }
4465
4466 if (RHS.isInt()) {
4467 APSInt LHS =
4468 HandleIntToIntCast(Info, E, PromotedLHSType, SubobjType, Value);
4469 if (!handleIntIntBinOp(Info, E, LHS, Opcode, RHS.getInt(), LHS))
4470 return false;
4471 Value = HandleIntToIntCast(Info, E, SubobjType, PromotedLHSType, LHS);
4472 return true;
4473 } else if (RHS.isFloat()) {
4474 const FPOptions FPO = E->getFPFeaturesInEffect(
4475 Info.Ctx.getLangOpts());
4476 APFloat FValue(0.0);
4477 return HandleIntToFloatCast(Info, E, FPO, SubobjType, Value,
4478 PromotedLHSType, FValue) &&
4479 handleFloatFloatBinOp(Info, E, FValue, Opcode, RHS.getFloat()) &&
4480 HandleFloatToIntCast(Info, E, PromotedLHSType, FValue, SubobjType,
4481 Value);
4482 }
4483
4484 Info.FFDiag(E);
4485 return false;
4486 }
found__anonbf0ddd820d11::CompoundAssignSubobjectHandler4487 bool found(APFloat &Value, QualType SubobjType) {
4488 return checkConst(SubobjType) &&
4489 HandleFloatToFloatCast(Info, E, SubobjType, PromotedLHSType,
4490 Value) &&
4491 handleFloatFloatBinOp(Info, E, Value, Opcode, RHS.getFloat()) &&
4492 HandleFloatToFloatCast(Info, E, PromotedLHSType, SubobjType, Value);
4493 }
foundPointer__anonbf0ddd820d11::CompoundAssignSubobjectHandler4494 bool foundPointer(APValue &Subobj, QualType SubobjType) {
4495 if (!checkConst(SubobjType))
4496 return false;
4497
4498 QualType PointeeType;
4499 if (const PointerType *PT = SubobjType->getAs<PointerType>())
4500 PointeeType = PT->getPointeeType();
4501
4502 if (PointeeType.isNull() || !RHS.isInt() ||
4503 (Opcode != BO_Add && Opcode != BO_Sub)) {
4504 Info.FFDiag(E);
4505 return false;
4506 }
4507
4508 APSInt Offset = RHS.getInt();
4509 if (Opcode == BO_Sub)
4510 negateAsSigned(Offset);
4511
4512 LValue LVal;
4513 LVal.setFrom(Info.Ctx, Subobj);
4514 if (!HandleLValueArrayAdjustment(Info, E, LVal, PointeeType, Offset))
4515 return false;
4516 LVal.moveInto(Subobj);
4517 return true;
4518 }
4519 };
4520 } // end anonymous namespace
4521
4522 const AccessKinds CompoundAssignSubobjectHandler::AccessKind;
4523
4524 /// Perform a compound assignment of LVal <op>= RVal.
handleCompoundAssignment(EvalInfo & Info,const CompoundAssignOperator * E,const LValue & LVal,QualType LValType,QualType PromotedLValType,BinaryOperatorKind Opcode,const APValue & RVal)4525 static bool handleCompoundAssignment(EvalInfo &Info,
4526 const CompoundAssignOperator *E,
4527 const LValue &LVal, QualType LValType,
4528 QualType PromotedLValType,
4529 BinaryOperatorKind Opcode,
4530 const APValue &RVal) {
4531 if (LVal.Designator.Invalid)
4532 return false;
4533
4534 if (!Info.getLangOpts().CPlusPlus14) {
4535 Info.FFDiag(E);
4536 return false;
4537 }
4538
4539 CompleteObject Obj = findCompleteObject(Info, E, AK_Assign, LVal, LValType);
4540 CompoundAssignSubobjectHandler Handler = { Info, E, PromotedLValType, Opcode,
4541 RVal };
4542 return Obj && findSubobject(Info, E, Obj, LVal.Designator, Handler);
4543 }
4544
4545 namespace {
4546 struct IncDecSubobjectHandler {
4547 EvalInfo &Info;
4548 const UnaryOperator *E;
4549 AccessKinds AccessKind;
4550 APValue *Old;
4551
4552 typedef bool result_type;
4553
checkConst__anonbf0ddd820e11::IncDecSubobjectHandler4554 bool checkConst(QualType QT) {
4555 // Assigning to a const object has undefined behavior.
4556 if (QT.isConstQualified()) {
4557 Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT;
4558 return false;
4559 }
4560 return true;
4561 }
4562
failed__anonbf0ddd820e11::IncDecSubobjectHandler4563 bool failed() { return false; }
found__anonbf0ddd820e11::IncDecSubobjectHandler4564 bool found(APValue &Subobj, QualType SubobjType) {
4565 // Stash the old value. Also clear Old, so we don't clobber it later
4566 // if we're post-incrementing a complex.
4567 if (Old) {
4568 *Old = Subobj;
4569 Old = nullptr;
4570 }
4571
4572 switch (Subobj.getKind()) {
4573 case APValue::Int:
4574 return found(Subobj.getInt(), SubobjType);
4575 case APValue::Float:
4576 return found(Subobj.getFloat(), SubobjType);
4577 case APValue::ComplexInt:
4578 return found(Subobj.getComplexIntReal(),
4579 SubobjType->castAs<ComplexType>()->getElementType()
4580 .withCVRQualifiers(SubobjType.getCVRQualifiers()));
4581 case APValue::ComplexFloat:
4582 return found(Subobj.getComplexFloatReal(),
4583 SubobjType->castAs<ComplexType>()->getElementType()
4584 .withCVRQualifiers(SubobjType.getCVRQualifiers()));
4585 case APValue::LValue:
4586 return foundPointer(Subobj, SubobjType);
4587 default:
4588 // FIXME: can this happen?
4589 Info.FFDiag(E);
4590 return false;
4591 }
4592 }
found__anonbf0ddd820e11::IncDecSubobjectHandler4593 bool found(APSInt &Value, QualType SubobjType) {
4594 if (!checkConst(SubobjType))
4595 return false;
4596
4597 if (!SubobjType->isIntegerType()) {
4598 // We don't support increment / decrement on integer-cast-to-pointer
4599 // values.
4600 Info.FFDiag(E);
4601 return false;
4602 }
4603
4604 if (Old) *Old = APValue(Value);
4605
4606 // bool arithmetic promotes to int, and the conversion back to bool
4607 // doesn't reduce mod 2^n, so special-case it.
4608 if (SubobjType->isBooleanType()) {
4609 if (AccessKind == AK_Increment)
4610 Value = 1;
4611 else
4612 Value = !Value;
4613 return true;
4614 }
4615
4616 bool WasNegative = Value.isNegative();
4617 if (AccessKind == AK_Increment) {
4618 ++Value;
4619
4620 if (!WasNegative && Value.isNegative() && E->canOverflow()) {
4621 APSInt ActualValue(Value, /*IsUnsigned*/true);
4622 return HandleOverflow(Info, E, ActualValue, SubobjType);
4623 }
4624 } else {
4625 --Value;
4626
4627 if (WasNegative && !Value.isNegative() && E->canOverflow()) {
4628 unsigned BitWidth = Value.getBitWidth();
4629 APSInt ActualValue(Value.sext(BitWidth + 1), /*IsUnsigned*/false);
4630 ActualValue.setBit(BitWidth);
4631 return HandleOverflow(Info, E, ActualValue, SubobjType);
4632 }
4633 }
4634 return true;
4635 }
found__anonbf0ddd820e11::IncDecSubobjectHandler4636 bool found(APFloat &Value, QualType SubobjType) {
4637 if (!checkConst(SubobjType))
4638 return false;
4639
4640 if (Old) *Old = APValue(Value);
4641
4642 APFloat One(Value.getSemantics(), 1);
4643 llvm::RoundingMode RM = getActiveRoundingMode(Info, E);
4644 APFloat::opStatus St;
4645 if (AccessKind == AK_Increment)
4646 St = Value.add(One, RM);
4647 else
4648 St = Value.subtract(One, RM);
4649 return checkFloatingPointResult(Info, E, St);
4650 }
foundPointer__anonbf0ddd820e11::IncDecSubobjectHandler4651 bool foundPointer(APValue &Subobj, QualType SubobjType) {
4652 if (!checkConst(SubobjType))
4653 return false;
4654
4655 QualType PointeeType;
4656 if (const PointerType *PT = SubobjType->getAs<PointerType>())
4657 PointeeType = PT->getPointeeType();
4658 else {
4659 Info.FFDiag(E);
4660 return false;
4661 }
4662
4663 LValue LVal;
4664 LVal.setFrom(Info.Ctx, Subobj);
4665 if (!HandleLValueArrayAdjustment(Info, E, LVal, PointeeType,
4666 AccessKind == AK_Increment ? 1 : -1))
4667 return false;
4668 LVal.moveInto(Subobj);
4669 return true;
4670 }
4671 };
4672 } // end anonymous namespace
4673
4674 /// Perform an increment or decrement on LVal.
handleIncDec(EvalInfo & Info,const Expr * E,const LValue & LVal,QualType LValType,bool IsIncrement,APValue * Old)4675 static bool handleIncDec(EvalInfo &Info, const Expr *E, const LValue &LVal,
4676 QualType LValType, bool IsIncrement, APValue *Old) {
4677 if (LVal.Designator.Invalid)
4678 return false;
4679
4680 if (!Info.getLangOpts().CPlusPlus14) {
4681 Info.FFDiag(E);
4682 return false;
4683 }
4684
4685 AccessKinds AK = IsIncrement ? AK_Increment : AK_Decrement;
4686 CompleteObject Obj = findCompleteObject(Info, E, AK, LVal, LValType);
4687 IncDecSubobjectHandler Handler = {Info, cast<UnaryOperator>(E), AK, Old};
4688 return Obj && findSubobject(Info, E, Obj, LVal.Designator, Handler);
4689 }
4690
4691 /// Build an lvalue for the object argument of a member function call.
EvaluateObjectArgument(EvalInfo & Info,const Expr * Object,LValue & This)4692 static bool EvaluateObjectArgument(EvalInfo &Info, const Expr *Object,
4693 LValue &This) {
4694 if (Object->getType()->isPointerType() && Object->isPRValue())
4695 return EvaluatePointer(Object, This, Info);
4696
4697 if (Object->isGLValue())
4698 return EvaluateLValue(Object, This, Info);
4699
4700 if (Object->getType()->isLiteralType(Info.Ctx))
4701 return EvaluateTemporary(Object, This, Info);
4702
4703 if (Object->getType()->isRecordType() && Object->isPRValue())
4704 return EvaluateTemporary(Object, This, Info);
4705
4706 Info.FFDiag(Object, diag::note_constexpr_nonliteral) << Object->getType();
4707 return false;
4708 }
4709
4710 /// HandleMemberPointerAccess - Evaluate a member access operation and build an
4711 /// lvalue referring to the result.
4712 ///
4713 /// \param Info - Information about the ongoing evaluation.
4714 /// \param LV - An lvalue referring to the base of the member pointer.
4715 /// \param RHS - The member pointer expression.
4716 /// \param IncludeMember - Specifies whether the member itself is included in
4717 /// the resulting LValue subobject designator. This is not possible when
4718 /// creating a bound member function.
4719 /// \return The field or method declaration to which the member pointer refers,
4720 /// or 0 if evaluation fails.
HandleMemberPointerAccess(EvalInfo & Info,QualType LVType,LValue & LV,const Expr * RHS,bool IncludeMember=true)4721 static const ValueDecl *HandleMemberPointerAccess(EvalInfo &Info,
4722 QualType LVType,
4723 LValue &LV,
4724 const Expr *RHS,
4725 bool IncludeMember = true) {
4726 MemberPtr MemPtr;
4727 if (!EvaluateMemberPointer(RHS, MemPtr, Info))
4728 return nullptr;
4729
4730 // C++11 [expr.mptr.oper]p6: If the second operand is the null pointer to
4731 // member value, the behavior is undefined.
4732 if (!MemPtr.getDecl()) {
4733 // FIXME: Specific diagnostic.
4734 Info.FFDiag(RHS);
4735 return nullptr;
4736 }
4737
4738 if (MemPtr.isDerivedMember()) {
4739 // This is a member of some derived class. Truncate LV appropriately.
4740 // The end of the derived-to-base path for the base object must match the
4741 // derived-to-base path for the member pointer.
4742 if (LV.Designator.MostDerivedPathLength + MemPtr.Path.size() >
4743 LV.Designator.Entries.size()) {
4744 Info.FFDiag(RHS);
4745 return nullptr;
4746 }
4747 unsigned PathLengthToMember =
4748 LV.Designator.Entries.size() - MemPtr.Path.size();
4749 for (unsigned I = 0, N = MemPtr.Path.size(); I != N; ++I) {
4750 const CXXRecordDecl *LVDecl = getAsBaseClass(
4751 LV.Designator.Entries[PathLengthToMember + I]);
4752 const CXXRecordDecl *MPDecl = MemPtr.Path[I];
4753 if (LVDecl->getCanonicalDecl() != MPDecl->getCanonicalDecl()) {
4754 Info.FFDiag(RHS);
4755 return nullptr;
4756 }
4757 }
4758
4759 // Truncate the lvalue to the appropriate derived class.
4760 if (!CastToDerivedClass(Info, RHS, LV, MemPtr.getContainingRecord(),
4761 PathLengthToMember))
4762 return nullptr;
4763 } else if (!MemPtr.Path.empty()) {
4764 // Extend the LValue path with the member pointer's path.
4765 LV.Designator.Entries.reserve(LV.Designator.Entries.size() +
4766 MemPtr.Path.size() + IncludeMember);
4767
4768 // Walk down to the appropriate base class.
4769 if (const PointerType *PT = LVType->getAs<PointerType>())
4770 LVType = PT->getPointeeType();
4771 const CXXRecordDecl *RD = LVType->getAsCXXRecordDecl();
4772 assert(RD && "member pointer access on non-class-type expression");
4773 // The first class in the path is that of the lvalue.
4774 for (unsigned I = 1, N = MemPtr.Path.size(); I != N; ++I) {
4775 const CXXRecordDecl *Base = MemPtr.Path[N - I - 1];
4776 if (!HandleLValueDirectBase(Info, RHS, LV, RD, Base))
4777 return nullptr;
4778 RD = Base;
4779 }
4780 // Finally cast to the class containing the member.
4781 if (!HandleLValueDirectBase(Info, RHS, LV, RD,
4782 MemPtr.getContainingRecord()))
4783 return nullptr;
4784 }
4785
4786 // Add the member. Note that we cannot build bound member functions here.
4787 if (IncludeMember) {
4788 if (const FieldDecl *FD = dyn_cast<FieldDecl>(MemPtr.getDecl())) {
4789 if (!HandleLValueMember(Info, RHS, LV, FD))
4790 return nullptr;
4791 } else if (const IndirectFieldDecl *IFD =
4792 dyn_cast<IndirectFieldDecl>(MemPtr.getDecl())) {
4793 if (!HandleLValueIndirectMember(Info, RHS, LV, IFD))
4794 return nullptr;
4795 } else {
4796 llvm_unreachable("can't construct reference to bound member function");
4797 }
4798 }
4799
4800 return MemPtr.getDecl();
4801 }
4802
HandleMemberPointerAccess(EvalInfo & Info,const BinaryOperator * BO,LValue & LV,bool IncludeMember=true)4803 static const ValueDecl *HandleMemberPointerAccess(EvalInfo &Info,
4804 const BinaryOperator *BO,
4805 LValue &LV,
4806 bool IncludeMember = true) {
4807 assert(BO->getOpcode() == BO_PtrMemD || BO->getOpcode() == BO_PtrMemI);
4808
4809 if (!EvaluateObjectArgument(Info, BO->getLHS(), LV)) {
4810 if (Info.noteFailure()) {
4811 MemberPtr MemPtr;
4812 EvaluateMemberPointer(BO->getRHS(), MemPtr, Info);
4813 }
4814 return nullptr;
4815 }
4816
4817 return HandleMemberPointerAccess(Info, BO->getLHS()->getType(), LV,
4818 BO->getRHS(), IncludeMember);
4819 }
4820
4821 /// HandleBaseToDerivedCast - Apply the given base-to-derived cast operation on
4822 /// the provided lvalue, which currently refers to the base object.
HandleBaseToDerivedCast(EvalInfo & Info,const CastExpr * E,LValue & Result)4823 static bool HandleBaseToDerivedCast(EvalInfo &Info, const CastExpr *E,
4824 LValue &Result) {
4825 SubobjectDesignator &D = Result.Designator;
4826 if (D.Invalid || !Result.checkNullPointer(Info, E, CSK_Derived))
4827 return false;
4828
4829 QualType TargetQT = E->getType();
4830 if (const PointerType *PT = TargetQT->getAs<PointerType>())
4831 TargetQT = PT->getPointeeType();
4832
4833 // Check this cast lands within the final derived-to-base subobject path.
4834 if (D.MostDerivedPathLength + E->path_size() > D.Entries.size()) {
4835 Info.CCEDiag(E, diag::note_constexpr_invalid_downcast)
4836 << D.MostDerivedType << TargetQT;
4837 return false;
4838 }
4839
4840 // Check the type of the final cast. We don't need to check the path,
4841 // since a cast can only be formed if the path is unique.
4842 unsigned NewEntriesSize = D.Entries.size() - E->path_size();
4843 const CXXRecordDecl *TargetType = TargetQT->getAsCXXRecordDecl();
4844 const CXXRecordDecl *FinalType;
4845 if (NewEntriesSize == D.MostDerivedPathLength)
4846 FinalType = D.MostDerivedType->getAsCXXRecordDecl();
4847 else
4848 FinalType = getAsBaseClass(D.Entries[NewEntriesSize - 1]);
4849 if (FinalType->getCanonicalDecl() != TargetType->getCanonicalDecl()) {
4850 Info.CCEDiag(E, diag::note_constexpr_invalid_downcast)
4851 << D.MostDerivedType << TargetQT;
4852 return false;
4853 }
4854
4855 // Truncate the lvalue to the appropriate derived class.
4856 return CastToDerivedClass(Info, E, Result, TargetType, NewEntriesSize);
4857 }
4858
4859 /// Get the value to use for a default-initialized object of type T.
4860 /// Return false if it encounters something invalid.
handleDefaultInitValue(QualType T,APValue & Result)4861 static bool handleDefaultInitValue(QualType T, APValue &Result) {
4862 bool Success = true;
4863
4864 // If there is already a value present don't overwrite it.
4865 if (!Result.isAbsent())
4866 return true;
4867
4868 if (auto *RD = T->getAsCXXRecordDecl()) {
4869 if (RD->isInvalidDecl()) {
4870 Result = APValue();
4871 return false;
4872 }
4873 if (RD->isUnion()) {
4874 Result = APValue((const FieldDecl *)nullptr);
4875 return true;
4876 }
4877 Result = APValue(APValue::UninitStruct(), RD->getNumBases(),
4878 std::distance(RD->field_begin(), RD->field_end()));
4879
4880 unsigned Index = 0;
4881 for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
4882 End = RD->bases_end();
4883 I != End; ++I, ++Index)
4884 Success &=
4885 handleDefaultInitValue(I->getType(), Result.getStructBase(Index));
4886
4887 for (const auto *I : RD->fields()) {
4888 if (I->isUnnamedBitfield())
4889 continue;
4890 Success &= handleDefaultInitValue(
4891 I->getType(), Result.getStructField(I->getFieldIndex()));
4892 }
4893 return Success;
4894 }
4895
4896 if (auto *AT =
4897 dyn_cast_or_null<ConstantArrayType>(T->getAsArrayTypeUnsafe())) {
4898 Result = APValue(APValue::UninitArray(), 0, AT->getSize().getZExtValue());
4899 if (Result.hasArrayFiller())
4900 Success &=
4901 handleDefaultInitValue(AT->getElementType(), Result.getArrayFiller());
4902
4903 return Success;
4904 }
4905
4906 Result = APValue::IndeterminateValue();
4907 return true;
4908 }
4909
4910 namespace {
4911 enum EvalStmtResult {
4912 /// Evaluation failed.
4913 ESR_Failed,
4914 /// Hit a 'return' statement.
4915 ESR_Returned,
4916 /// Evaluation succeeded.
4917 ESR_Succeeded,
4918 /// Hit a 'continue' statement.
4919 ESR_Continue,
4920 /// Hit a 'break' statement.
4921 ESR_Break,
4922 /// Still scanning for 'case' or 'default' statement.
4923 ESR_CaseNotFound
4924 };
4925 }
4926
EvaluateVarDecl(EvalInfo & Info,const VarDecl * VD)4927 static bool EvaluateVarDecl(EvalInfo &Info, const VarDecl *VD) {
4928 if (VD->isInvalidDecl())
4929 return false;
4930 // We don't need to evaluate the initializer for a static local.
4931 if (!VD->hasLocalStorage())
4932 return true;
4933
4934 LValue Result;
4935 APValue &Val = Info.CurrentCall->createTemporary(VD, VD->getType(),
4936 ScopeKind::Block, Result);
4937
4938 const Expr *InitE = VD->getInit();
4939 if (!InitE) {
4940 if (VD->getType()->isDependentType())
4941 return Info.noteSideEffect();
4942 return handleDefaultInitValue(VD->getType(), Val);
4943 }
4944 if (InitE->isValueDependent())
4945 return false;
4946
4947 if (!EvaluateInPlace(Val, Info, Result, InitE)) {
4948 // Wipe out any partially-computed value, to allow tracking that this
4949 // evaluation failed.
4950 Val = APValue();
4951 return false;
4952 }
4953
4954 return true;
4955 }
4956
EvaluateDecl(EvalInfo & Info,const Decl * D)4957 static bool EvaluateDecl(EvalInfo &Info, const Decl *D) {
4958 bool OK = true;
4959
4960 if (const VarDecl *VD = dyn_cast<VarDecl>(D))
4961 OK &= EvaluateVarDecl(Info, VD);
4962
4963 if (const DecompositionDecl *DD = dyn_cast<DecompositionDecl>(D))
4964 for (auto *BD : DD->bindings())
4965 if (auto *VD = BD->getHoldingVar())
4966 OK &= EvaluateDecl(Info, VD);
4967
4968 return OK;
4969 }
4970
EvaluateDependentExpr(const Expr * E,EvalInfo & Info)4971 static bool EvaluateDependentExpr(const Expr *E, EvalInfo &Info) {
4972 assert(E->isValueDependent());
4973 if (Info.noteSideEffect())
4974 return true;
4975 assert(E->containsErrors() && "valid value-dependent expression should never "
4976 "reach invalid code path.");
4977 return false;
4978 }
4979
4980 /// Evaluate a condition (either a variable declaration or an expression).
EvaluateCond(EvalInfo & Info,const VarDecl * CondDecl,const Expr * Cond,bool & Result)4981 static bool EvaluateCond(EvalInfo &Info, const VarDecl *CondDecl,
4982 const Expr *Cond, bool &Result) {
4983 if (Cond->isValueDependent())
4984 return false;
4985 FullExpressionRAII Scope(Info);
4986 if (CondDecl && !EvaluateDecl(Info, CondDecl))
4987 return false;
4988 if (!EvaluateAsBooleanCondition(Cond, Result, Info))
4989 return false;
4990 return Scope.destroy();
4991 }
4992
4993 namespace {
4994 /// A location where the result (returned value) of evaluating a
4995 /// statement should be stored.
4996 struct StmtResult {
4997 /// The APValue that should be filled in with the returned value.
4998 APValue &Value;
4999 /// The location containing the result, if any (used to support RVO).
5000 const LValue *Slot;
5001 };
5002
5003 struct TempVersionRAII {
5004 CallStackFrame &Frame;
5005
TempVersionRAII__anonbf0ddd821011::TempVersionRAII5006 TempVersionRAII(CallStackFrame &Frame) : Frame(Frame) {
5007 Frame.pushTempVersion();
5008 }
5009
~TempVersionRAII__anonbf0ddd821011::TempVersionRAII5010 ~TempVersionRAII() {
5011 Frame.popTempVersion();
5012 }
5013 };
5014
5015 }
5016
5017 static EvalStmtResult EvaluateStmt(StmtResult &Result, EvalInfo &Info,
5018 const Stmt *S,
5019 const SwitchCase *SC = nullptr);
5020
5021 /// Evaluate the body of a loop, and translate the result as appropriate.
EvaluateLoopBody(StmtResult & Result,EvalInfo & Info,const Stmt * Body,const SwitchCase * Case=nullptr)5022 static EvalStmtResult EvaluateLoopBody(StmtResult &Result, EvalInfo &Info,
5023 const Stmt *Body,
5024 const SwitchCase *Case = nullptr) {
5025 BlockScopeRAII Scope(Info);
5026
5027 EvalStmtResult ESR = EvaluateStmt(Result, Info, Body, Case);
5028 if (ESR != ESR_Failed && ESR != ESR_CaseNotFound && !Scope.destroy())
5029 ESR = ESR_Failed;
5030
5031 switch (ESR) {
5032 case ESR_Break:
5033 return ESR_Succeeded;
5034 case ESR_Succeeded:
5035 case ESR_Continue:
5036 return ESR_Continue;
5037 case ESR_Failed:
5038 case ESR_Returned:
5039 case ESR_CaseNotFound:
5040 return ESR;
5041 }
5042 llvm_unreachable("Invalid EvalStmtResult!");
5043 }
5044
5045 /// Evaluate a switch statement.
EvaluateSwitch(StmtResult & Result,EvalInfo & Info,const SwitchStmt * SS)5046 static EvalStmtResult EvaluateSwitch(StmtResult &Result, EvalInfo &Info,
5047 const SwitchStmt *SS) {
5048 BlockScopeRAII Scope(Info);
5049
5050 // Evaluate the switch condition.
5051 APSInt Value;
5052 {
5053 if (const Stmt *Init = SS->getInit()) {
5054 EvalStmtResult ESR = EvaluateStmt(Result, Info, Init);
5055 if (ESR != ESR_Succeeded) {
5056 if (ESR != ESR_Failed && !Scope.destroy())
5057 ESR = ESR_Failed;
5058 return ESR;
5059 }
5060 }
5061
5062 FullExpressionRAII CondScope(Info);
5063 if (SS->getConditionVariable() &&
5064 !EvaluateDecl(Info, SS->getConditionVariable()))
5065 return ESR_Failed;
5066 if (SS->getCond()->isValueDependent()) {
5067 // We don't know what the value is, and which branch should jump to.
5068 EvaluateDependentExpr(SS->getCond(), Info);
5069 return ESR_Failed;
5070 }
5071 if (!EvaluateInteger(SS->getCond(), Value, Info))
5072 return ESR_Failed;
5073
5074 if (!CondScope.destroy())
5075 return ESR_Failed;
5076 }
5077
5078 // Find the switch case corresponding to the value of the condition.
5079 // FIXME: Cache this lookup.
5080 const SwitchCase *Found = nullptr;
5081 for (const SwitchCase *SC = SS->getSwitchCaseList(); SC;
5082 SC = SC->getNextSwitchCase()) {
5083 if (isa<DefaultStmt>(SC)) {
5084 Found = SC;
5085 continue;
5086 }
5087
5088 const CaseStmt *CS = cast<CaseStmt>(SC);
5089 APSInt LHS = CS->getLHS()->EvaluateKnownConstInt(Info.Ctx);
5090 APSInt RHS = CS->getRHS() ? CS->getRHS()->EvaluateKnownConstInt(Info.Ctx)
5091 : LHS;
5092 if (LHS <= Value && Value <= RHS) {
5093 Found = SC;
5094 break;
5095 }
5096 }
5097
5098 if (!Found)
5099 return Scope.destroy() ? ESR_Succeeded : ESR_Failed;
5100
5101 // Search the switch body for the switch case and evaluate it from there.
5102 EvalStmtResult ESR = EvaluateStmt(Result, Info, SS->getBody(), Found);
5103 if (ESR != ESR_Failed && ESR != ESR_CaseNotFound && !Scope.destroy())
5104 return ESR_Failed;
5105
5106 switch (ESR) {
5107 case ESR_Break:
5108 return ESR_Succeeded;
5109 case ESR_Succeeded:
5110 case ESR_Continue:
5111 case ESR_Failed:
5112 case ESR_Returned:
5113 return ESR;
5114 case ESR_CaseNotFound:
5115 // This can only happen if the switch case is nested within a statement
5116 // expression. We have no intention of supporting that.
5117 Info.FFDiag(Found->getBeginLoc(),
5118 diag::note_constexpr_stmt_expr_unsupported);
5119 return ESR_Failed;
5120 }
5121 llvm_unreachable("Invalid EvalStmtResult!");
5122 }
5123
CheckLocalVariableDeclaration(EvalInfo & Info,const VarDecl * VD)5124 static bool CheckLocalVariableDeclaration(EvalInfo &Info, const VarDecl *VD) {
5125 // An expression E is a core constant expression unless the evaluation of E
5126 // would evaluate one of the following: [C++23] - a control flow that passes
5127 // through a declaration of a variable with static or thread storage duration
5128 // unless that variable is usable in constant expressions.
5129 if (VD->isLocalVarDecl() && VD->isStaticLocal() &&
5130 !VD->isUsableInConstantExpressions(Info.Ctx)) {
5131 Info.CCEDiag(VD->getLocation(), diag::note_constexpr_static_local)
5132 << (VD->getTSCSpec() == TSCS_unspecified ? 0 : 1) << VD;
5133 return false;
5134 }
5135 return true;
5136 }
5137
5138 // Evaluate a statement.
EvaluateStmt(StmtResult & Result,EvalInfo & Info,const Stmt * S,const SwitchCase * Case)5139 static EvalStmtResult EvaluateStmt(StmtResult &Result, EvalInfo &Info,
5140 const Stmt *S, const SwitchCase *Case) {
5141 if (!Info.nextStep(S))
5142 return ESR_Failed;
5143
5144 // If we're hunting down a 'case' or 'default' label, recurse through
5145 // substatements until we hit the label.
5146 if (Case) {
5147 switch (S->getStmtClass()) {
5148 case Stmt::CompoundStmtClass:
5149 // FIXME: Precompute which substatement of a compound statement we
5150 // would jump to, and go straight there rather than performing a
5151 // linear scan each time.
5152 case Stmt::LabelStmtClass:
5153 case Stmt::AttributedStmtClass:
5154 case Stmt::DoStmtClass:
5155 break;
5156
5157 case Stmt::CaseStmtClass:
5158 case Stmt::DefaultStmtClass:
5159 if (Case == S)
5160 Case = nullptr;
5161 break;
5162
5163 case Stmt::IfStmtClass: {
5164 // FIXME: Precompute which side of an 'if' we would jump to, and go
5165 // straight there rather than scanning both sides.
5166 const IfStmt *IS = cast<IfStmt>(S);
5167
5168 // Wrap the evaluation in a block scope, in case it's a DeclStmt
5169 // preceded by our switch label.
5170 BlockScopeRAII Scope(Info);
5171
5172 // Step into the init statement in case it brings an (uninitialized)
5173 // variable into scope.
5174 if (const Stmt *Init = IS->getInit()) {
5175 EvalStmtResult ESR = EvaluateStmt(Result, Info, Init, Case);
5176 if (ESR != ESR_CaseNotFound) {
5177 assert(ESR != ESR_Succeeded);
5178 return ESR;
5179 }
5180 }
5181
5182 // Condition variable must be initialized if it exists.
5183 // FIXME: We can skip evaluating the body if there's a condition
5184 // variable, as there can't be any case labels within it.
5185 // (The same is true for 'for' statements.)
5186
5187 EvalStmtResult ESR = EvaluateStmt(Result, Info, IS->getThen(), Case);
5188 if (ESR == ESR_Failed)
5189 return ESR;
5190 if (ESR != ESR_CaseNotFound)
5191 return Scope.destroy() ? ESR : ESR_Failed;
5192 if (!IS->getElse())
5193 return ESR_CaseNotFound;
5194
5195 ESR = EvaluateStmt(Result, Info, IS->getElse(), Case);
5196 if (ESR == ESR_Failed)
5197 return ESR;
5198 if (ESR != ESR_CaseNotFound)
5199 return Scope.destroy() ? ESR : ESR_Failed;
5200 return ESR_CaseNotFound;
5201 }
5202
5203 case Stmt::WhileStmtClass: {
5204 EvalStmtResult ESR =
5205 EvaluateLoopBody(Result, Info, cast<WhileStmt>(S)->getBody(), Case);
5206 if (ESR != ESR_Continue)
5207 return ESR;
5208 break;
5209 }
5210
5211 case Stmt::ForStmtClass: {
5212 const ForStmt *FS = cast<ForStmt>(S);
5213 BlockScopeRAII Scope(Info);
5214
5215 // Step into the init statement in case it brings an (uninitialized)
5216 // variable into scope.
5217 if (const Stmt *Init = FS->getInit()) {
5218 EvalStmtResult ESR = EvaluateStmt(Result, Info, Init, Case);
5219 if (ESR != ESR_CaseNotFound) {
5220 assert(ESR != ESR_Succeeded);
5221 return ESR;
5222 }
5223 }
5224
5225 EvalStmtResult ESR =
5226 EvaluateLoopBody(Result, Info, FS->getBody(), Case);
5227 if (ESR != ESR_Continue)
5228 return ESR;
5229 if (const auto *Inc = FS->getInc()) {
5230 if (Inc->isValueDependent()) {
5231 if (!EvaluateDependentExpr(Inc, Info))
5232 return ESR_Failed;
5233 } else {
5234 FullExpressionRAII IncScope(Info);
5235 if (!EvaluateIgnoredValue(Info, Inc) || !IncScope.destroy())
5236 return ESR_Failed;
5237 }
5238 }
5239 break;
5240 }
5241
5242 case Stmt::DeclStmtClass: {
5243 // Start the lifetime of any uninitialized variables we encounter. They
5244 // might be used by the selected branch of the switch.
5245 const DeclStmt *DS = cast<DeclStmt>(S);
5246 for (const auto *D : DS->decls()) {
5247 if (const auto *VD = dyn_cast<VarDecl>(D)) {
5248 if (!CheckLocalVariableDeclaration(Info, VD))
5249 return ESR_Failed;
5250 if (VD->hasLocalStorage() && !VD->getInit())
5251 if (!EvaluateVarDecl(Info, VD))
5252 return ESR_Failed;
5253 // FIXME: If the variable has initialization that can't be jumped
5254 // over, bail out of any immediately-surrounding compound-statement
5255 // too. There can't be any case labels here.
5256 }
5257 }
5258 return ESR_CaseNotFound;
5259 }
5260
5261 default:
5262 return ESR_CaseNotFound;
5263 }
5264 }
5265
5266 switch (S->getStmtClass()) {
5267 default:
5268 if (const Expr *E = dyn_cast<Expr>(S)) {
5269 if (E->isValueDependent()) {
5270 if (!EvaluateDependentExpr(E, Info))
5271 return ESR_Failed;
5272 } else {
5273 // Don't bother evaluating beyond an expression-statement which couldn't
5274 // be evaluated.
5275 // FIXME: Do we need the FullExpressionRAII object here?
5276 // VisitExprWithCleanups should create one when necessary.
5277 FullExpressionRAII Scope(Info);
5278 if (!EvaluateIgnoredValue(Info, E) || !Scope.destroy())
5279 return ESR_Failed;
5280 }
5281 return ESR_Succeeded;
5282 }
5283
5284 Info.FFDiag(S->getBeginLoc()) << S->getSourceRange();
5285 return ESR_Failed;
5286
5287 case Stmt::NullStmtClass:
5288 return ESR_Succeeded;
5289
5290 case Stmt::DeclStmtClass: {
5291 const DeclStmt *DS = cast<DeclStmt>(S);
5292 for (const auto *D : DS->decls()) {
5293 const VarDecl *VD = dyn_cast_or_null<VarDecl>(D);
5294 if (VD && !CheckLocalVariableDeclaration(Info, VD))
5295 return ESR_Failed;
5296 // Each declaration initialization is its own full-expression.
5297 FullExpressionRAII Scope(Info);
5298 if (!EvaluateDecl(Info, D) && !Info.noteFailure())
5299 return ESR_Failed;
5300 if (!Scope.destroy())
5301 return ESR_Failed;
5302 }
5303 return ESR_Succeeded;
5304 }
5305
5306 case Stmt::ReturnStmtClass: {
5307 const Expr *RetExpr = cast<ReturnStmt>(S)->getRetValue();
5308 FullExpressionRAII Scope(Info);
5309 if (RetExpr && RetExpr->isValueDependent()) {
5310 EvaluateDependentExpr(RetExpr, Info);
5311 // We know we returned, but we don't know what the value is.
5312 return ESR_Failed;
5313 }
5314 if (RetExpr &&
5315 !(Result.Slot
5316 ? EvaluateInPlace(Result.Value, Info, *Result.Slot, RetExpr)
5317 : Evaluate(Result.Value, Info, RetExpr)))
5318 return ESR_Failed;
5319 return Scope.destroy() ? ESR_Returned : ESR_Failed;
5320 }
5321
5322 case Stmt::CompoundStmtClass: {
5323 BlockScopeRAII Scope(Info);
5324
5325 const CompoundStmt *CS = cast<CompoundStmt>(S);
5326 for (const auto *BI : CS->body()) {
5327 EvalStmtResult ESR = EvaluateStmt(Result, Info, BI, Case);
5328 if (ESR == ESR_Succeeded)
5329 Case = nullptr;
5330 else if (ESR != ESR_CaseNotFound) {
5331 if (ESR != ESR_Failed && !Scope.destroy())
5332 return ESR_Failed;
5333 return ESR;
5334 }
5335 }
5336 if (Case)
5337 return ESR_CaseNotFound;
5338 return Scope.destroy() ? ESR_Succeeded : ESR_Failed;
5339 }
5340
5341 case Stmt::IfStmtClass: {
5342 const IfStmt *IS = cast<IfStmt>(S);
5343
5344 // Evaluate the condition, as either a var decl or as an expression.
5345 BlockScopeRAII Scope(Info);
5346 if (const Stmt *Init = IS->getInit()) {
5347 EvalStmtResult ESR = EvaluateStmt(Result, Info, Init);
5348 if (ESR != ESR_Succeeded) {
5349 if (ESR != ESR_Failed && !Scope.destroy())
5350 return ESR_Failed;
5351 return ESR;
5352 }
5353 }
5354 bool Cond;
5355 if (IS->isConsteval()) {
5356 Cond = IS->isNonNegatedConsteval();
5357 // If we are not in a constant context, if consteval should not evaluate
5358 // to true.
5359 if (!Info.InConstantContext)
5360 Cond = !Cond;
5361 } else if (!EvaluateCond(Info, IS->getConditionVariable(), IS->getCond(),
5362 Cond))
5363 return ESR_Failed;
5364
5365 if (const Stmt *SubStmt = Cond ? IS->getThen() : IS->getElse()) {
5366 EvalStmtResult ESR = EvaluateStmt(Result, Info, SubStmt);
5367 if (ESR != ESR_Succeeded) {
5368 if (ESR != ESR_Failed && !Scope.destroy())
5369 return ESR_Failed;
5370 return ESR;
5371 }
5372 }
5373 return Scope.destroy() ? ESR_Succeeded : ESR_Failed;
5374 }
5375
5376 case Stmt::WhileStmtClass: {
5377 const WhileStmt *WS = cast<WhileStmt>(S);
5378 while (true) {
5379 BlockScopeRAII Scope(Info);
5380 bool Continue;
5381 if (!EvaluateCond(Info, WS->getConditionVariable(), WS->getCond(),
5382 Continue))
5383 return ESR_Failed;
5384 if (!Continue)
5385 break;
5386
5387 EvalStmtResult ESR = EvaluateLoopBody(Result, Info, WS->getBody());
5388 if (ESR != ESR_Continue) {
5389 if (ESR != ESR_Failed && !Scope.destroy())
5390 return ESR_Failed;
5391 return ESR;
5392 }
5393 if (!Scope.destroy())
5394 return ESR_Failed;
5395 }
5396 return ESR_Succeeded;
5397 }
5398
5399 case Stmt::DoStmtClass: {
5400 const DoStmt *DS = cast<DoStmt>(S);
5401 bool Continue;
5402 do {
5403 EvalStmtResult ESR = EvaluateLoopBody(Result, Info, DS->getBody(), Case);
5404 if (ESR != ESR_Continue)
5405 return ESR;
5406 Case = nullptr;
5407
5408 if (DS->getCond()->isValueDependent()) {
5409 EvaluateDependentExpr(DS->getCond(), Info);
5410 // Bailout as we don't know whether to keep going or terminate the loop.
5411 return ESR_Failed;
5412 }
5413 FullExpressionRAII CondScope(Info);
5414 if (!EvaluateAsBooleanCondition(DS->getCond(), Continue, Info) ||
5415 !CondScope.destroy())
5416 return ESR_Failed;
5417 } while (Continue);
5418 return ESR_Succeeded;
5419 }
5420
5421 case Stmt::ForStmtClass: {
5422 const ForStmt *FS = cast<ForStmt>(S);
5423 BlockScopeRAII ForScope(Info);
5424 if (FS->getInit()) {
5425 EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getInit());
5426 if (ESR != ESR_Succeeded) {
5427 if (ESR != ESR_Failed && !ForScope.destroy())
5428 return ESR_Failed;
5429 return ESR;
5430 }
5431 }
5432 while (true) {
5433 BlockScopeRAII IterScope(Info);
5434 bool Continue = true;
5435 if (FS->getCond() && !EvaluateCond(Info, FS->getConditionVariable(),
5436 FS->getCond(), Continue))
5437 return ESR_Failed;
5438 if (!Continue)
5439 break;
5440
5441 EvalStmtResult ESR = EvaluateLoopBody(Result, Info, FS->getBody());
5442 if (ESR != ESR_Continue) {
5443 if (ESR != ESR_Failed && (!IterScope.destroy() || !ForScope.destroy()))
5444 return ESR_Failed;
5445 return ESR;
5446 }
5447
5448 if (const auto *Inc = FS->getInc()) {
5449 if (Inc->isValueDependent()) {
5450 if (!EvaluateDependentExpr(Inc, Info))
5451 return ESR_Failed;
5452 } else {
5453 FullExpressionRAII IncScope(Info);
5454 if (!EvaluateIgnoredValue(Info, Inc) || !IncScope.destroy())
5455 return ESR_Failed;
5456 }
5457 }
5458
5459 if (!IterScope.destroy())
5460 return ESR_Failed;
5461 }
5462 return ForScope.destroy() ? ESR_Succeeded : ESR_Failed;
5463 }
5464
5465 case Stmt::CXXForRangeStmtClass: {
5466 const CXXForRangeStmt *FS = cast<CXXForRangeStmt>(S);
5467 BlockScopeRAII Scope(Info);
5468
5469 // Evaluate the init-statement if present.
5470 if (FS->getInit()) {
5471 EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getInit());
5472 if (ESR != ESR_Succeeded) {
5473 if (ESR != ESR_Failed && !Scope.destroy())
5474 return ESR_Failed;
5475 return ESR;
5476 }
5477 }
5478
5479 // Initialize the __range variable.
5480 EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getRangeStmt());
5481 if (ESR != ESR_Succeeded) {
5482 if (ESR != ESR_Failed && !Scope.destroy())
5483 return ESR_Failed;
5484 return ESR;
5485 }
5486
5487 // In error-recovery cases it's possible to get here even if we failed to
5488 // synthesize the __begin and __end variables.
5489 if (!FS->getBeginStmt() || !FS->getEndStmt() || !FS->getCond())
5490 return ESR_Failed;
5491
5492 // Create the __begin and __end iterators.
5493 ESR = EvaluateStmt(Result, Info, FS->getBeginStmt());
5494 if (ESR != ESR_Succeeded) {
5495 if (ESR != ESR_Failed && !Scope.destroy())
5496 return ESR_Failed;
5497 return ESR;
5498 }
5499 ESR = EvaluateStmt(Result, Info, FS->getEndStmt());
5500 if (ESR != ESR_Succeeded) {
5501 if (ESR != ESR_Failed && !Scope.destroy())
5502 return ESR_Failed;
5503 return ESR;
5504 }
5505
5506 while (true) {
5507 // Condition: __begin != __end.
5508 {
5509 if (FS->getCond()->isValueDependent()) {
5510 EvaluateDependentExpr(FS->getCond(), Info);
5511 // We don't know whether to keep going or terminate the loop.
5512 return ESR_Failed;
5513 }
5514 bool Continue = true;
5515 FullExpressionRAII CondExpr(Info);
5516 if (!EvaluateAsBooleanCondition(FS->getCond(), Continue, Info))
5517 return ESR_Failed;
5518 if (!Continue)
5519 break;
5520 }
5521
5522 // User's variable declaration, initialized by *__begin.
5523 BlockScopeRAII InnerScope(Info);
5524 ESR = EvaluateStmt(Result, Info, FS->getLoopVarStmt());
5525 if (ESR != ESR_Succeeded) {
5526 if (ESR != ESR_Failed && (!InnerScope.destroy() || !Scope.destroy()))
5527 return ESR_Failed;
5528 return ESR;
5529 }
5530
5531 // Loop body.
5532 ESR = EvaluateLoopBody(Result, Info, FS->getBody());
5533 if (ESR != ESR_Continue) {
5534 if (ESR != ESR_Failed && (!InnerScope.destroy() || !Scope.destroy()))
5535 return ESR_Failed;
5536 return ESR;
5537 }
5538 if (FS->getInc()->isValueDependent()) {
5539 if (!EvaluateDependentExpr(FS->getInc(), Info))
5540 return ESR_Failed;
5541 } else {
5542 // Increment: ++__begin
5543 if (!EvaluateIgnoredValue(Info, FS->getInc()))
5544 return ESR_Failed;
5545 }
5546
5547 if (!InnerScope.destroy())
5548 return ESR_Failed;
5549 }
5550
5551 return Scope.destroy() ? ESR_Succeeded : ESR_Failed;
5552 }
5553
5554 case Stmt::SwitchStmtClass:
5555 return EvaluateSwitch(Result, Info, cast<SwitchStmt>(S));
5556
5557 case Stmt::ContinueStmtClass:
5558 return ESR_Continue;
5559
5560 case Stmt::BreakStmtClass:
5561 return ESR_Break;
5562
5563 case Stmt::LabelStmtClass:
5564 return EvaluateStmt(Result, Info, cast<LabelStmt>(S)->getSubStmt(), Case);
5565
5566 case Stmt::AttributedStmtClass: {
5567 const auto *AS = cast<AttributedStmt>(S);
5568 const auto *SS = AS->getSubStmt();
5569 MSConstexprContextRAII ConstexprContext(
5570 *Info.CurrentCall, hasSpecificAttr<MSConstexprAttr>(AS->getAttrs()) &&
5571 isa<ReturnStmt>(SS));
5572 return EvaluateStmt(Result, Info, SS, Case);
5573 }
5574
5575 case Stmt::CaseStmtClass:
5576 case Stmt::DefaultStmtClass:
5577 return EvaluateStmt(Result, Info, cast<SwitchCase>(S)->getSubStmt(), Case);
5578 case Stmt::CXXTryStmtClass:
5579 // Evaluate try blocks by evaluating all sub statements.
5580 return EvaluateStmt(Result, Info, cast<CXXTryStmt>(S)->getTryBlock(), Case);
5581 }
5582 }
5583
5584 /// CheckTrivialDefaultConstructor - Check whether a constructor is a trivial
5585 /// default constructor. If so, we'll fold it whether or not it's marked as
5586 /// constexpr. If it is marked as constexpr, we will never implicitly define it,
5587 /// so we need special handling.
CheckTrivialDefaultConstructor(EvalInfo & Info,SourceLocation Loc,const CXXConstructorDecl * CD,bool IsValueInitialization)5588 static bool CheckTrivialDefaultConstructor(EvalInfo &Info, SourceLocation Loc,
5589 const CXXConstructorDecl *CD,
5590 bool IsValueInitialization) {
5591 if (!CD->isTrivial() || !CD->isDefaultConstructor())
5592 return false;
5593
5594 // Value-initialization does not call a trivial default constructor, so such a
5595 // call is a core constant expression whether or not the constructor is
5596 // constexpr.
5597 if (!CD->isConstexpr() && !IsValueInitialization) {
5598 if (Info.getLangOpts().CPlusPlus11) {
5599 // FIXME: If DiagDecl is an implicitly-declared special member function,
5600 // we should be much more explicit about why it's not constexpr.
5601 Info.CCEDiag(Loc, diag::note_constexpr_invalid_function, 1)
5602 << /*IsConstexpr*/0 << /*IsConstructor*/1 << CD;
5603 Info.Note(CD->getLocation(), diag::note_declared_at);
5604 } else {
5605 Info.CCEDiag(Loc, diag::note_invalid_subexpr_in_const_expr);
5606 }
5607 }
5608 return true;
5609 }
5610
5611 /// CheckConstexprFunction - Check that a function can be called in a constant
5612 /// expression.
CheckConstexprFunction(EvalInfo & Info,SourceLocation CallLoc,const FunctionDecl * Declaration,const FunctionDecl * Definition,const Stmt * Body)5613 static bool CheckConstexprFunction(EvalInfo &Info, SourceLocation CallLoc,
5614 const FunctionDecl *Declaration,
5615 const FunctionDecl *Definition,
5616 const Stmt *Body) {
5617 // Potential constant expressions can contain calls to declared, but not yet
5618 // defined, constexpr functions.
5619 if (Info.checkingPotentialConstantExpression() && !Definition &&
5620 Declaration->isConstexpr())
5621 return false;
5622
5623 // Bail out if the function declaration itself is invalid. We will
5624 // have produced a relevant diagnostic while parsing it, so just
5625 // note the problematic sub-expression.
5626 if (Declaration->isInvalidDecl()) {
5627 Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr);
5628 return false;
5629 }
5630
5631 // DR1872: An instantiated virtual constexpr function can't be called in a
5632 // constant expression (prior to C++20). We can still constant-fold such a
5633 // call.
5634 if (!Info.Ctx.getLangOpts().CPlusPlus20 && isa<CXXMethodDecl>(Declaration) &&
5635 cast<CXXMethodDecl>(Declaration)->isVirtual())
5636 Info.CCEDiag(CallLoc, diag::note_constexpr_virtual_call);
5637
5638 if (Definition && Definition->isInvalidDecl()) {
5639 Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr);
5640 return false;
5641 }
5642
5643 // Can we evaluate this function call?
5644 if (Definition && Body &&
5645 (Definition->isConstexpr() || (Info.CurrentCall->CanEvalMSConstexpr &&
5646 Definition->hasAttr<MSConstexprAttr>())))
5647 return true;
5648
5649 if (Info.getLangOpts().CPlusPlus11) {
5650 const FunctionDecl *DiagDecl = Definition ? Definition : Declaration;
5651
5652 // If this function is not constexpr because it is an inherited
5653 // non-constexpr constructor, diagnose that directly.
5654 auto *CD = dyn_cast<CXXConstructorDecl>(DiagDecl);
5655 if (CD && CD->isInheritingConstructor()) {
5656 auto *Inherited = CD->getInheritedConstructor().getConstructor();
5657 if (!Inherited->isConstexpr())
5658 DiagDecl = CD = Inherited;
5659 }
5660
5661 // FIXME: If DiagDecl is an implicitly-declared special member function
5662 // or an inheriting constructor, we should be much more explicit about why
5663 // it's not constexpr.
5664 if (CD && CD->isInheritingConstructor())
5665 Info.FFDiag(CallLoc, diag::note_constexpr_invalid_inhctor, 1)
5666 << CD->getInheritedConstructor().getConstructor()->getParent();
5667 else
5668 Info.FFDiag(CallLoc, diag::note_constexpr_invalid_function, 1)
5669 << DiagDecl->isConstexpr() << (bool)CD << DiagDecl;
5670 Info.Note(DiagDecl->getLocation(), diag::note_declared_at);
5671 } else {
5672 Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr);
5673 }
5674 return false;
5675 }
5676
5677 namespace {
5678 struct CheckDynamicTypeHandler {
5679 AccessKinds AccessKind;
5680 typedef bool result_type;
failed__anonbf0ddd821111::CheckDynamicTypeHandler5681 bool failed() { return false; }
found__anonbf0ddd821111::CheckDynamicTypeHandler5682 bool found(APValue &Subobj, QualType SubobjType) { return true; }
found__anonbf0ddd821111::CheckDynamicTypeHandler5683 bool found(APSInt &Value, QualType SubobjType) { return true; }
found__anonbf0ddd821111::CheckDynamicTypeHandler5684 bool found(APFloat &Value, QualType SubobjType) { return true; }
5685 };
5686 } // end anonymous namespace
5687
5688 /// Check that we can access the notional vptr of an object / determine its
5689 /// dynamic type.
checkDynamicType(EvalInfo & Info,const Expr * E,const LValue & This,AccessKinds AK,bool Polymorphic)5690 static bool checkDynamicType(EvalInfo &Info, const Expr *E, const LValue &This,
5691 AccessKinds AK, bool Polymorphic) {
5692 if (This.Designator.Invalid)
5693 return false;
5694
5695 CompleteObject Obj = findCompleteObject(Info, E, AK, This, QualType());
5696
5697 if (!Obj)
5698 return false;
5699
5700 if (!Obj.Value) {
5701 // The object is not usable in constant expressions, so we can't inspect
5702 // its value to see if it's in-lifetime or what the active union members
5703 // are. We can still check for a one-past-the-end lvalue.
5704 if (This.Designator.isOnePastTheEnd() ||
5705 This.Designator.isMostDerivedAnUnsizedArray()) {
5706 Info.FFDiag(E, This.Designator.isOnePastTheEnd()
5707 ? diag::note_constexpr_access_past_end
5708 : diag::note_constexpr_access_unsized_array)
5709 << AK;
5710 return false;
5711 } else if (Polymorphic) {
5712 // Conservatively refuse to perform a polymorphic operation if we would
5713 // not be able to read a notional 'vptr' value.
5714 APValue Val;
5715 This.moveInto(Val);
5716 QualType StarThisType =
5717 Info.Ctx.getLValueReferenceType(This.Designator.getType(Info.Ctx));
5718 Info.FFDiag(E, diag::note_constexpr_polymorphic_unknown_dynamic_type)
5719 << AK << Val.getAsString(Info.Ctx, StarThisType);
5720 return false;
5721 }
5722 return true;
5723 }
5724
5725 CheckDynamicTypeHandler Handler{AK};
5726 return Obj && findSubobject(Info, E, Obj, This.Designator, Handler);
5727 }
5728
5729 /// Check that the pointee of the 'this' pointer in a member function call is
5730 /// either within its lifetime or in its period of construction or destruction.
5731 static bool
checkNonVirtualMemberCallThisPointer(EvalInfo & Info,const Expr * E,const LValue & This,const CXXMethodDecl * NamedMember)5732 checkNonVirtualMemberCallThisPointer(EvalInfo &Info, const Expr *E,
5733 const LValue &This,
5734 const CXXMethodDecl *NamedMember) {
5735 return checkDynamicType(
5736 Info, E, This,
5737 isa<CXXDestructorDecl>(NamedMember) ? AK_Destroy : AK_MemberCall, false);
5738 }
5739
5740 struct DynamicType {
5741 /// The dynamic class type of the object.
5742 const CXXRecordDecl *Type;
5743 /// The corresponding path length in the lvalue.
5744 unsigned PathLength;
5745 };
5746
getBaseClassType(SubobjectDesignator & Designator,unsigned PathLength)5747 static const CXXRecordDecl *getBaseClassType(SubobjectDesignator &Designator,
5748 unsigned PathLength) {
5749 assert(PathLength >= Designator.MostDerivedPathLength && PathLength <=
5750 Designator.Entries.size() && "invalid path length");
5751 return (PathLength == Designator.MostDerivedPathLength)
5752 ? Designator.MostDerivedType->getAsCXXRecordDecl()
5753 : getAsBaseClass(Designator.Entries[PathLength - 1]);
5754 }
5755
5756 /// Determine the dynamic type of an object.
ComputeDynamicType(EvalInfo & Info,const Expr * E,LValue & This,AccessKinds AK)5757 static std::optional<DynamicType> ComputeDynamicType(EvalInfo &Info,
5758 const Expr *E,
5759 LValue &This,
5760 AccessKinds AK) {
5761 // If we don't have an lvalue denoting an object of class type, there is no
5762 // meaningful dynamic type. (We consider objects of non-class type to have no
5763 // dynamic type.)
5764 if (!checkDynamicType(Info, E, This, AK, true))
5765 return std::nullopt;
5766
5767 // Refuse to compute a dynamic type in the presence of virtual bases. This
5768 // shouldn't happen other than in constant-folding situations, since literal
5769 // types can't have virtual bases.
5770 //
5771 // Note that consumers of DynamicType assume that the type has no virtual
5772 // bases, and will need modifications if this restriction is relaxed.
5773 const CXXRecordDecl *Class =
5774 This.Designator.MostDerivedType->getAsCXXRecordDecl();
5775 if (!Class || Class->getNumVBases()) {
5776 Info.FFDiag(E);
5777 return std::nullopt;
5778 }
5779
5780 // FIXME: For very deep class hierarchies, it might be beneficial to use a
5781 // binary search here instead. But the overwhelmingly common case is that
5782 // we're not in the middle of a constructor, so it probably doesn't matter
5783 // in practice.
5784 ArrayRef<APValue::LValuePathEntry> Path = This.Designator.Entries;
5785 for (unsigned PathLength = This.Designator.MostDerivedPathLength;
5786 PathLength <= Path.size(); ++PathLength) {
5787 switch (Info.isEvaluatingCtorDtor(This.getLValueBase(),
5788 Path.slice(0, PathLength))) {
5789 case ConstructionPhase::Bases:
5790 case ConstructionPhase::DestroyingBases:
5791 // We're constructing or destroying a base class. This is not the dynamic
5792 // type.
5793 break;
5794
5795 case ConstructionPhase::None:
5796 case ConstructionPhase::AfterBases:
5797 case ConstructionPhase::AfterFields:
5798 case ConstructionPhase::Destroying:
5799 // We've finished constructing the base classes and not yet started
5800 // destroying them again, so this is the dynamic type.
5801 return DynamicType{getBaseClassType(This.Designator, PathLength),
5802 PathLength};
5803 }
5804 }
5805
5806 // CWG issue 1517: we're constructing a base class of the object described by
5807 // 'This', so that object has not yet begun its period of construction and
5808 // any polymorphic operation on it results in undefined behavior.
5809 Info.FFDiag(E);
5810 return std::nullopt;
5811 }
5812
5813 /// Perform virtual dispatch.
HandleVirtualDispatch(EvalInfo & Info,const Expr * E,LValue & This,const CXXMethodDecl * Found,llvm::SmallVectorImpl<QualType> & CovariantAdjustmentPath)5814 static const CXXMethodDecl *HandleVirtualDispatch(
5815 EvalInfo &Info, const Expr *E, LValue &This, const CXXMethodDecl *Found,
5816 llvm::SmallVectorImpl<QualType> &CovariantAdjustmentPath) {
5817 std::optional<DynamicType> DynType = ComputeDynamicType(
5818 Info, E, This,
5819 isa<CXXDestructorDecl>(Found) ? AK_Destroy : AK_MemberCall);
5820 if (!DynType)
5821 return nullptr;
5822
5823 // Find the final overrider. It must be declared in one of the classes on the
5824 // path from the dynamic type to the static type.
5825 // FIXME: If we ever allow literal types to have virtual base classes, that
5826 // won't be true.
5827 const CXXMethodDecl *Callee = Found;
5828 unsigned PathLength = DynType->PathLength;
5829 for (/**/; PathLength <= This.Designator.Entries.size(); ++PathLength) {
5830 const CXXRecordDecl *Class = getBaseClassType(This.Designator, PathLength);
5831 const CXXMethodDecl *Overrider =
5832 Found->getCorrespondingMethodDeclaredInClass(Class, false);
5833 if (Overrider) {
5834 Callee = Overrider;
5835 break;
5836 }
5837 }
5838
5839 // C++2a [class.abstract]p6:
5840 // the effect of making a virtual call to a pure virtual function [...] is
5841 // undefined
5842 if (Callee->isPureVirtual()) {
5843 Info.FFDiag(E, diag::note_constexpr_pure_virtual_call, 1) << Callee;
5844 Info.Note(Callee->getLocation(), diag::note_declared_at);
5845 return nullptr;
5846 }
5847
5848 // If necessary, walk the rest of the path to determine the sequence of
5849 // covariant adjustment steps to apply.
5850 if (!Info.Ctx.hasSameUnqualifiedType(Callee->getReturnType(),
5851 Found->getReturnType())) {
5852 CovariantAdjustmentPath.push_back(Callee->getReturnType());
5853 for (unsigned CovariantPathLength = PathLength + 1;
5854 CovariantPathLength != This.Designator.Entries.size();
5855 ++CovariantPathLength) {
5856 const CXXRecordDecl *NextClass =
5857 getBaseClassType(This.Designator, CovariantPathLength);
5858 const CXXMethodDecl *Next =
5859 Found->getCorrespondingMethodDeclaredInClass(NextClass, false);
5860 if (Next && !Info.Ctx.hasSameUnqualifiedType(
5861 Next->getReturnType(), CovariantAdjustmentPath.back()))
5862 CovariantAdjustmentPath.push_back(Next->getReturnType());
5863 }
5864 if (!Info.Ctx.hasSameUnqualifiedType(Found->getReturnType(),
5865 CovariantAdjustmentPath.back()))
5866 CovariantAdjustmentPath.push_back(Found->getReturnType());
5867 }
5868
5869 // Perform 'this' adjustment.
5870 if (!CastToDerivedClass(Info, E, This, Callee->getParent(), PathLength))
5871 return nullptr;
5872
5873 return Callee;
5874 }
5875
5876 /// Perform the adjustment from a value returned by a virtual function to
5877 /// a value of the statically expected type, which may be a pointer or
5878 /// reference to a base class of the returned type.
HandleCovariantReturnAdjustment(EvalInfo & Info,const Expr * E,APValue & Result,ArrayRef<QualType> Path)5879 static bool HandleCovariantReturnAdjustment(EvalInfo &Info, const Expr *E,
5880 APValue &Result,
5881 ArrayRef<QualType> Path) {
5882 assert(Result.isLValue() &&
5883 "unexpected kind of APValue for covariant return");
5884 if (Result.isNullPointer())
5885 return true;
5886
5887 LValue LVal;
5888 LVal.setFrom(Info.Ctx, Result);
5889
5890 const CXXRecordDecl *OldClass = Path[0]->getPointeeCXXRecordDecl();
5891 for (unsigned I = 1; I != Path.size(); ++I) {
5892 const CXXRecordDecl *NewClass = Path[I]->getPointeeCXXRecordDecl();
5893 assert(OldClass && NewClass && "unexpected kind of covariant return");
5894 if (OldClass != NewClass &&
5895 !CastToBaseClass(Info, E, LVal, OldClass, NewClass))
5896 return false;
5897 OldClass = NewClass;
5898 }
5899
5900 LVal.moveInto(Result);
5901 return true;
5902 }
5903
5904 /// Determine whether \p Base, which is known to be a direct base class of
5905 /// \p Derived, is a public base class.
isBaseClassPublic(const CXXRecordDecl * Derived,const CXXRecordDecl * Base)5906 static bool isBaseClassPublic(const CXXRecordDecl *Derived,
5907 const CXXRecordDecl *Base) {
5908 for (const CXXBaseSpecifier &BaseSpec : Derived->bases()) {
5909 auto *BaseClass = BaseSpec.getType()->getAsCXXRecordDecl();
5910 if (BaseClass && declaresSameEntity(BaseClass, Base))
5911 return BaseSpec.getAccessSpecifier() == AS_public;
5912 }
5913 llvm_unreachable("Base is not a direct base of Derived");
5914 }
5915
5916 /// Apply the given dynamic cast operation on the provided lvalue.
5917 ///
5918 /// This implements the hard case of dynamic_cast, requiring a "runtime check"
5919 /// to find a suitable target subobject.
HandleDynamicCast(EvalInfo & Info,const ExplicitCastExpr * E,LValue & Ptr)5920 static bool HandleDynamicCast(EvalInfo &Info, const ExplicitCastExpr *E,
5921 LValue &Ptr) {
5922 // We can't do anything with a non-symbolic pointer value.
5923 SubobjectDesignator &D = Ptr.Designator;
5924 if (D.Invalid)
5925 return false;
5926
5927 // C++ [expr.dynamic.cast]p6:
5928 // If v is a null pointer value, the result is a null pointer value.
5929 if (Ptr.isNullPointer() && !E->isGLValue())
5930 return true;
5931
5932 // For all the other cases, we need the pointer to point to an object within
5933 // its lifetime / period of construction / destruction, and we need to know
5934 // its dynamic type.
5935 std::optional<DynamicType> DynType =
5936 ComputeDynamicType(Info, E, Ptr, AK_DynamicCast);
5937 if (!DynType)
5938 return false;
5939
5940 // C++ [expr.dynamic.cast]p7:
5941 // If T is "pointer to cv void", then the result is a pointer to the most
5942 // derived object
5943 if (E->getType()->isVoidPointerType())
5944 return CastToDerivedClass(Info, E, Ptr, DynType->Type, DynType->PathLength);
5945
5946 const CXXRecordDecl *C = E->getTypeAsWritten()->getPointeeCXXRecordDecl();
5947 assert(C && "dynamic_cast target is not void pointer nor class");
5948 CanQualType CQT = Info.Ctx.getCanonicalType(Info.Ctx.getRecordType(C));
5949
5950 auto RuntimeCheckFailed = [&] (CXXBasePaths *Paths) {
5951 // C++ [expr.dynamic.cast]p9:
5952 if (!E->isGLValue()) {
5953 // The value of a failed cast to pointer type is the null pointer value
5954 // of the required result type.
5955 Ptr.setNull(Info.Ctx, E->getType());
5956 return true;
5957 }
5958
5959 // A failed cast to reference type throws [...] std::bad_cast.
5960 unsigned DiagKind;
5961 if (!Paths && (declaresSameEntity(DynType->Type, C) ||
5962 DynType->Type->isDerivedFrom(C)))
5963 DiagKind = 0;
5964 else if (!Paths || Paths->begin() == Paths->end())
5965 DiagKind = 1;
5966 else if (Paths->isAmbiguous(CQT))
5967 DiagKind = 2;
5968 else {
5969 assert(Paths->front().Access != AS_public && "why did the cast fail?");
5970 DiagKind = 3;
5971 }
5972 Info.FFDiag(E, diag::note_constexpr_dynamic_cast_to_reference_failed)
5973 << DiagKind << Ptr.Designator.getType(Info.Ctx)
5974 << Info.Ctx.getRecordType(DynType->Type)
5975 << E->getType().getUnqualifiedType();
5976 return false;
5977 };
5978
5979 // Runtime check, phase 1:
5980 // Walk from the base subobject towards the derived object looking for the
5981 // target type.
5982 for (int PathLength = Ptr.Designator.Entries.size();
5983 PathLength >= (int)DynType->PathLength; --PathLength) {
5984 const CXXRecordDecl *Class = getBaseClassType(Ptr.Designator, PathLength);
5985 if (declaresSameEntity(Class, C))
5986 return CastToDerivedClass(Info, E, Ptr, Class, PathLength);
5987 // We can only walk across public inheritance edges.
5988 if (PathLength > (int)DynType->PathLength &&
5989 !isBaseClassPublic(getBaseClassType(Ptr.Designator, PathLength - 1),
5990 Class))
5991 return RuntimeCheckFailed(nullptr);
5992 }
5993
5994 // Runtime check, phase 2:
5995 // Search the dynamic type for an unambiguous public base of type C.
5996 CXXBasePaths Paths(/*FindAmbiguities=*/true,
5997 /*RecordPaths=*/true, /*DetectVirtual=*/false);
5998 if (DynType->Type->isDerivedFrom(C, Paths) && !Paths.isAmbiguous(CQT) &&
5999 Paths.front().Access == AS_public) {
6000 // Downcast to the dynamic type...
6001 if (!CastToDerivedClass(Info, E, Ptr, DynType->Type, DynType->PathLength))
6002 return false;
6003 // ... then upcast to the chosen base class subobject.
6004 for (CXXBasePathElement &Elem : Paths.front())
6005 if (!HandleLValueBase(Info, E, Ptr, Elem.Class, Elem.Base))
6006 return false;
6007 return true;
6008 }
6009
6010 // Otherwise, the runtime check fails.
6011 return RuntimeCheckFailed(&Paths);
6012 }
6013
6014 namespace {
6015 struct StartLifetimeOfUnionMemberHandler {
6016 EvalInfo &Info;
6017 const Expr *LHSExpr;
6018 const FieldDecl *Field;
6019 bool DuringInit;
6020 bool Failed = false;
6021 static const AccessKinds AccessKind = AK_Assign;
6022
6023 typedef bool result_type;
failed__anonbf0ddd821311::StartLifetimeOfUnionMemberHandler6024 bool failed() { return Failed; }
found__anonbf0ddd821311::StartLifetimeOfUnionMemberHandler6025 bool found(APValue &Subobj, QualType SubobjType) {
6026 // We are supposed to perform no initialization but begin the lifetime of
6027 // the object. We interpret that as meaning to do what default
6028 // initialization of the object would do if all constructors involved were
6029 // trivial:
6030 // * All base, non-variant member, and array element subobjects' lifetimes
6031 // begin
6032 // * No variant members' lifetimes begin
6033 // * All scalar subobjects whose lifetimes begin have indeterminate values
6034 assert(SubobjType->isUnionType());
6035 if (declaresSameEntity(Subobj.getUnionField(), Field)) {
6036 // This union member is already active. If it's also in-lifetime, there's
6037 // nothing to do.
6038 if (Subobj.getUnionValue().hasValue())
6039 return true;
6040 } else if (DuringInit) {
6041 // We're currently in the process of initializing a different union
6042 // member. If we carried on, that initialization would attempt to
6043 // store to an inactive union member, resulting in undefined behavior.
6044 Info.FFDiag(LHSExpr,
6045 diag::note_constexpr_union_member_change_during_init);
6046 return false;
6047 }
6048 APValue Result;
6049 Failed = !handleDefaultInitValue(Field->getType(), Result);
6050 Subobj.setUnion(Field, Result);
6051 return true;
6052 }
found__anonbf0ddd821311::StartLifetimeOfUnionMemberHandler6053 bool found(APSInt &Value, QualType SubobjType) {
6054 llvm_unreachable("wrong value kind for union object");
6055 }
found__anonbf0ddd821311::StartLifetimeOfUnionMemberHandler6056 bool found(APFloat &Value, QualType SubobjType) {
6057 llvm_unreachable("wrong value kind for union object");
6058 }
6059 };
6060 } // end anonymous namespace
6061
6062 const AccessKinds StartLifetimeOfUnionMemberHandler::AccessKind;
6063
6064 /// Handle a builtin simple-assignment or a call to a trivial assignment
6065 /// operator whose left-hand side might involve a union member access. If it
6066 /// does, implicitly start the lifetime of any accessed union elements per
6067 /// C++20 [class.union]5.
MaybeHandleUnionActiveMemberChange(EvalInfo & Info,const Expr * LHSExpr,const LValue & LHS)6068 static bool MaybeHandleUnionActiveMemberChange(EvalInfo &Info,
6069 const Expr *LHSExpr,
6070 const LValue &LHS) {
6071 if (LHS.InvalidBase || LHS.Designator.Invalid)
6072 return false;
6073
6074 llvm::SmallVector<std::pair<unsigned, const FieldDecl*>, 4> UnionPathLengths;
6075 // C++ [class.union]p5:
6076 // define the set S(E) of subexpressions of E as follows:
6077 unsigned PathLength = LHS.Designator.Entries.size();
6078 for (const Expr *E = LHSExpr; E != nullptr;) {
6079 // -- If E is of the form A.B, S(E) contains the elements of S(A)...
6080 if (auto *ME = dyn_cast<MemberExpr>(E)) {
6081 auto *FD = dyn_cast<FieldDecl>(ME->getMemberDecl());
6082 // Note that we can't implicitly start the lifetime of a reference,
6083 // so we don't need to proceed any further if we reach one.
6084 if (!FD || FD->getType()->isReferenceType())
6085 break;
6086
6087 // ... and also contains A.B if B names a union member ...
6088 if (FD->getParent()->isUnion()) {
6089 // ... of a non-class, non-array type, or of a class type with a
6090 // trivial default constructor that is not deleted, or an array of
6091 // such types.
6092 auto *RD =
6093 FD->getType()->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
6094 if (!RD || RD->hasTrivialDefaultConstructor())
6095 UnionPathLengths.push_back({PathLength - 1, FD});
6096 }
6097
6098 E = ME->getBase();
6099 --PathLength;
6100 assert(declaresSameEntity(FD,
6101 LHS.Designator.Entries[PathLength]
6102 .getAsBaseOrMember().getPointer()));
6103
6104 // -- If E is of the form A[B] and is interpreted as a built-in array
6105 // subscripting operator, S(E) is [S(the array operand, if any)].
6106 } else if (auto *ASE = dyn_cast<ArraySubscriptExpr>(E)) {
6107 // Step over an ArrayToPointerDecay implicit cast.
6108 auto *Base = ASE->getBase()->IgnoreImplicit();
6109 if (!Base->getType()->isArrayType())
6110 break;
6111
6112 E = Base;
6113 --PathLength;
6114
6115 } else if (auto *ICE = dyn_cast<ImplicitCastExpr>(E)) {
6116 // Step over a derived-to-base conversion.
6117 E = ICE->getSubExpr();
6118 if (ICE->getCastKind() == CK_NoOp)
6119 continue;
6120 if (ICE->getCastKind() != CK_DerivedToBase &&
6121 ICE->getCastKind() != CK_UncheckedDerivedToBase)
6122 break;
6123 // Walk path backwards as we walk up from the base to the derived class.
6124 for (const CXXBaseSpecifier *Elt : llvm::reverse(ICE->path())) {
6125 if (Elt->isVirtual()) {
6126 // A class with virtual base classes never has a trivial default
6127 // constructor, so S(E) is empty in this case.
6128 E = nullptr;
6129 break;
6130 }
6131
6132 --PathLength;
6133 assert(declaresSameEntity(Elt->getType()->getAsCXXRecordDecl(),
6134 LHS.Designator.Entries[PathLength]
6135 .getAsBaseOrMember().getPointer()));
6136 }
6137
6138 // -- Otherwise, S(E) is empty.
6139 } else {
6140 break;
6141 }
6142 }
6143
6144 // Common case: no unions' lifetimes are started.
6145 if (UnionPathLengths.empty())
6146 return true;
6147
6148 // if modification of X [would access an inactive union member], an object
6149 // of the type of X is implicitly created
6150 CompleteObject Obj =
6151 findCompleteObject(Info, LHSExpr, AK_Assign, LHS, LHSExpr->getType());
6152 if (!Obj)
6153 return false;
6154 for (std::pair<unsigned, const FieldDecl *> LengthAndField :
6155 llvm::reverse(UnionPathLengths)) {
6156 // Form a designator for the union object.
6157 SubobjectDesignator D = LHS.Designator;
6158 D.truncate(Info.Ctx, LHS.Base, LengthAndField.first);
6159
6160 bool DuringInit = Info.isEvaluatingCtorDtor(LHS.Base, D.Entries) ==
6161 ConstructionPhase::AfterBases;
6162 StartLifetimeOfUnionMemberHandler StartLifetime{
6163 Info, LHSExpr, LengthAndField.second, DuringInit};
6164 if (!findSubobject(Info, LHSExpr, Obj, D, StartLifetime))
6165 return false;
6166 }
6167
6168 return true;
6169 }
6170
EvaluateCallArg(const ParmVarDecl * PVD,const Expr * Arg,CallRef Call,EvalInfo & Info,bool NonNull=false)6171 static bool EvaluateCallArg(const ParmVarDecl *PVD, const Expr *Arg,
6172 CallRef Call, EvalInfo &Info,
6173 bool NonNull = false) {
6174 LValue LV;
6175 // Create the parameter slot and register its destruction. For a vararg
6176 // argument, create a temporary.
6177 // FIXME: For calling conventions that destroy parameters in the callee,
6178 // should we consider performing destruction when the function returns
6179 // instead?
6180 APValue &V = PVD ? Info.CurrentCall->createParam(Call, PVD, LV)
6181 : Info.CurrentCall->createTemporary(Arg, Arg->getType(),
6182 ScopeKind::Call, LV);
6183 if (!EvaluateInPlace(V, Info, LV, Arg))
6184 return false;
6185
6186 // Passing a null pointer to an __attribute__((nonnull)) parameter results in
6187 // undefined behavior, so is non-constant.
6188 if (NonNull && V.isLValue() && V.isNullPointer()) {
6189 Info.CCEDiag(Arg, diag::note_non_null_attribute_failed);
6190 return false;
6191 }
6192
6193 return true;
6194 }
6195
6196 /// Evaluate the arguments to a function call.
EvaluateArgs(ArrayRef<const Expr * > Args,CallRef Call,EvalInfo & Info,const FunctionDecl * Callee,bool RightToLeft=false)6197 static bool EvaluateArgs(ArrayRef<const Expr *> Args, CallRef Call,
6198 EvalInfo &Info, const FunctionDecl *Callee,
6199 bool RightToLeft = false) {
6200 bool Success = true;
6201 llvm::SmallBitVector ForbiddenNullArgs;
6202 if (Callee->hasAttr<NonNullAttr>()) {
6203 ForbiddenNullArgs.resize(Args.size());
6204 for (const auto *Attr : Callee->specific_attrs<NonNullAttr>()) {
6205 if (!Attr->args_size()) {
6206 ForbiddenNullArgs.set();
6207 break;
6208 } else
6209 for (auto Idx : Attr->args()) {
6210 unsigned ASTIdx = Idx.getASTIndex();
6211 if (ASTIdx >= Args.size())
6212 continue;
6213 ForbiddenNullArgs[ASTIdx] = true;
6214 }
6215 }
6216 }
6217 for (unsigned I = 0; I < Args.size(); I++) {
6218 unsigned Idx = RightToLeft ? Args.size() - I - 1 : I;
6219 const ParmVarDecl *PVD =
6220 Idx < Callee->getNumParams() ? Callee->getParamDecl(Idx) : nullptr;
6221 bool NonNull = !ForbiddenNullArgs.empty() && ForbiddenNullArgs[Idx];
6222 if (!EvaluateCallArg(PVD, Args[Idx], Call, Info, NonNull)) {
6223 // If we're checking for a potential constant expression, evaluate all
6224 // initializers even if some of them fail.
6225 if (!Info.noteFailure())
6226 return false;
6227 Success = false;
6228 }
6229 }
6230 return Success;
6231 }
6232
6233 /// Perform a trivial copy from Param, which is the parameter of a copy or move
6234 /// constructor or assignment operator.
handleTrivialCopy(EvalInfo & Info,const ParmVarDecl * Param,const Expr * E,APValue & Result,bool CopyObjectRepresentation)6235 static bool handleTrivialCopy(EvalInfo &Info, const ParmVarDecl *Param,
6236 const Expr *E, APValue &Result,
6237 bool CopyObjectRepresentation) {
6238 // Find the reference argument.
6239 CallStackFrame *Frame = Info.CurrentCall;
6240 APValue *RefValue = Info.getParamSlot(Frame->Arguments, Param);
6241 if (!RefValue) {
6242 Info.FFDiag(E);
6243 return false;
6244 }
6245
6246 // Copy out the contents of the RHS object.
6247 LValue RefLValue;
6248 RefLValue.setFrom(Info.Ctx, *RefValue);
6249 return handleLValueToRValueConversion(
6250 Info, E, Param->getType().getNonReferenceType(), RefLValue, Result,
6251 CopyObjectRepresentation);
6252 }
6253
6254 /// Evaluate a function call.
HandleFunctionCall(SourceLocation CallLoc,const FunctionDecl * Callee,const LValue * This,const Expr * E,ArrayRef<const Expr * > Args,CallRef Call,const Stmt * Body,EvalInfo & Info,APValue & Result,const LValue * ResultSlot)6255 static bool HandleFunctionCall(SourceLocation CallLoc,
6256 const FunctionDecl *Callee, const LValue *This,
6257 const Expr *E, ArrayRef<const Expr *> Args,
6258 CallRef Call, const Stmt *Body, EvalInfo &Info,
6259 APValue &Result, const LValue *ResultSlot) {
6260 if (!Info.CheckCallLimit(CallLoc))
6261 return false;
6262
6263 CallStackFrame Frame(Info, E->getSourceRange(), Callee, This, E, Call);
6264
6265 // For a trivial copy or move assignment, perform an APValue copy. This is
6266 // essential for unions, where the operations performed by the assignment
6267 // operator cannot be represented as statements.
6268 //
6269 // Skip this for non-union classes with no fields; in that case, the defaulted
6270 // copy/move does not actually read the object.
6271 const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(Callee);
6272 if (MD && MD->isDefaulted() &&
6273 (MD->getParent()->isUnion() ||
6274 (MD->isTrivial() &&
6275 isReadByLvalueToRvalueConversion(MD->getParent())))) {
6276 assert(This &&
6277 (MD->isCopyAssignmentOperator() || MD->isMoveAssignmentOperator()));
6278 APValue RHSValue;
6279 if (!handleTrivialCopy(Info, MD->getParamDecl(0), Args[0], RHSValue,
6280 MD->getParent()->isUnion()))
6281 return false;
6282 if (!handleAssignment(Info, Args[0], *This, MD->getThisType(),
6283 RHSValue))
6284 return false;
6285 This->moveInto(Result);
6286 return true;
6287 } else if (MD && isLambdaCallOperator(MD)) {
6288 // We're in a lambda; determine the lambda capture field maps unless we're
6289 // just constexpr checking a lambda's call operator. constexpr checking is
6290 // done before the captures have been added to the closure object (unless
6291 // we're inferring constexpr-ness), so we don't have access to them in this
6292 // case. But since we don't need the captures to constexpr check, we can
6293 // just ignore them.
6294 if (!Info.checkingPotentialConstantExpression())
6295 MD->getParent()->getCaptureFields(Frame.LambdaCaptureFields,
6296 Frame.LambdaThisCaptureField);
6297 }
6298
6299 StmtResult Ret = {Result, ResultSlot};
6300 EvalStmtResult ESR = EvaluateStmt(Ret, Info, Body);
6301 if (ESR == ESR_Succeeded) {
6302 if (Callee->getReturnType()->isVoidType())
6303 return true;
6304 Info.FFDiag(Callee->getEndLoc(), diag::note_constexpr_no_return);
6305 }
6306 return ESR == ESR_Returned;
6307 }
6308
6309 /// Evaluate a constructor call.
HandleConstructorCall(const Expr * E,const LValue & This,CallRef Call,const CXXConstructorDecl * Definition,EvalInfo & Info,APValue & Result)6310 static bool HandleConstructorCall(const Expr *E, const LValue &This,
6311 CallRef Call,
6312 const CXXConstructorDecl *Definition,
6313 EvalInfo &Info, APValue &Result) {
6314 SourceLocation CallLoc = E->getExprLoc();
6315 if (!Info.CheckCallLimit(CallLoc))
6316 return false;
6317
6318 const CXXRecordDecl *RD = Definition->getParent();
6319 if (RD->getNumVBases()) {
6320 Info.FFDiag(CallLoc, diag::note_constexpr_virtual_base) << RD;
6321 return false;
6322 }
6323
6324 EvalInfo::EvaluatingConstructorRAII EvalObj(
6325 Info,
6326 ObjectUnderConstruction{This.getLValueBase(), This.Designator.Entries},
6327 RD->getNumBases());
6328 CallStackFrame Frame(Info, E->getSourceRange(), Definition, &This, E, Call);
6329
6330 // FIXME: Creating an APValue just to hold a nonexistent return value is
6331 // wasteful.
6332 APValue RetVal;
6333 StmtResult Ret = {RetVal, nullptr};
6334
6335 // If it's a delegating constructor, delegate.
6336 if (Definition->isDelegatingConstructor()) {
6337 CXXConstructorDecl::init_const_iterator I = Definition->init_begin();
6338 if ((*I)->getInit()->isValueDependent()) {
6339 if (!EvaluateDependentExpr((*I)->getInit(), Info))
6340 return false;
6341 } else {
6342 FullExpressionRAII InitScope(Info);
6343 if (!EvaluateInPlace(Result, Info, This, (*I)->getInit()) ||
6344 !InitScope.destroy())
6345 return false;
6346 }
6347 return EvaluateStmt(Ret, Info, Definition->getBody()) != ESR_Failed;
6348 }
6349
6350 // For a trivial copy or move constructor, perform an APValue copy. This is
6351 // essential for unions (or classes with anonymous union members), where the
6352 // operations performed by the constructor cannot be represented by
6353 // ctor-initializers.
6354 //
6355 // Skip this for empty non-union classes; we should not perform an
6356 // lvalue-to-rvalue conversion on them because their copy constructor does not
6357 // actually read them.
6358 if (Definition->isDefaulted() && Definition->isCopyOrMoveConstructor() &&
6359 (Definition->getParent()->isUnion() ||
6360 (Definition->isTrivial() &&
6361 isReadByLvalueToRvalueConversion(Definition->getParent())))) {
6362 return handleTrivialCopy(Info, Definition->getParamDecl(0), E, Result,
6363 Definition->getParent()->isUnion());
6364 }
6365
6366 // Reserve space for the struct members.
6367 if (!Result.hasValue()) {
6368 if (!RD->isUnion())
6369 Result = APValue(APValue::UninitStruct(), RD->getNumBases(),
6370 std::distance(RD->field_begin(), RD->field_end()));
6371 else
6372 // A union starts with no active member.
6373 Result = APValue((const FieldDecl*)nullptr);
6374 }
6375
6376 if (RD->isInvalidDecl()) return false;
6377 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
6378
6379 // A scope for temporaries lifetime-extended by reference members.
6380 BlockScopeRAII LifetimeExtendedScope(Info);
6381
6382 bool Success = true;
6383 unsigned BasesSeen = 0;
6384 #ifndef NDEBUG
6385 CXXRecordDecl::base_class_const_iterator BaseIt = RD->bases_begin();
6386 #endif
6387 CXXRecordDecl::field_iterator FieldIt = RD->field_begin();
6388 auto SkipToField = [&](FieldDecl *FD, bool Indirect) {
6389 // We might be initializing the same field again if this is an indirect
6390 // field initialization.
6391 if (FieldIt == RD->field_end() ||
6392 FieldIt->getFieldIndex() > FD->getFieldIndex()) {
6393 assert(Indirect && "fields out of order?");
6394 return;
6395 }
6396
6397 // Default-initialize any fields with no explicit initializer.
6398 for (; !declaresSameEntity(*FieldIt, FD); ++FieldIt) {
6399 assert(FieldIt != RD->field_end() && "missing field?");
6400 if (!FieldIt->isUnnamedBitfield())
6401 Success &= handleDefaultInitValue(
6402 FieldIt->getType(),
6403 Result.getStructField(FieldIt->getFieldIndex()));
6404 }
6405 ++FieldIt;
6406 };
6407 for (const auto *I : Definition->inits()) {
6408 LValue Subobject = This;
6409 LValue SubobjectParent = This;
6410 APValue *Value = &Result;
6411
6412 // Determine the subobject to initialize.
6413 FieldDecl *FD = nullptr;
6414 if (I->isBaseInitializer()) {
6415 QualType BaseType(I->getBaseClass(), 0);
6416 #ifndef NDEBUG
6417 // Non-virtual base classes are initialized in the order in the class
6418 // definition. We have already checked for virtual base classes.
6419 assert(!BaseIt->isVirtual() && "virtual base for literal type");
6420 assert(Info.Ctx.hasSameType(BaseIt->getType(), BaseType) &&
6421 "base class initializers not in expected order");
6422 ++BaseIt;
6423 #endif
6424 if (!HandleLValueDirectBase(Info, I->getInit(), Subobject, RD,
6425 BaseType->getAsCXXRecordDecl(), &Layout))
6426 return false;
6427 Value = &Result.getStructBase(BasesSeen++);
6428 } else if ((FD = I->getMember())) {
6429 if (!HandleLValueMember(Info, I->getInit(), Subobject, FD, &Layout))
6430 return false;
6431 if (RD->isUnion()) {
6432 Result = APValue(FD);
6433 Value = &Result.getUnionValue();
6434 } else {
6435 SkipToField(FD, false);
6436 Value = &Result.getStructField(FD->getFieldIndex());
6437 }
6438 } else if (IndirectFieldDecl *IFD = I->getIndirectMember()) {
6439 // Walk the indirect field decl's chain to find the object to initialize,
6440 // and make sure we've initialized every step along it.
6441 auto IndirectFieldChain = IFD->chain();
6442 for (auto *C : IndirectFieldChain) {
6443 FD = cast<FieldDecl>(C);
6444 CXXRecordDecl *CD = cast<CXXRecordDecl>(FD->getParent());
6445 // Switch the union field if it differs. This happens if we had
6446 // preceding zero-initialization, and we're now initializing a union
6447 // subobject other than the first.
6448 // FIXME: In this case, the values of the other subobjects are
6449 // specified, since zero-initialization sets all padding bits to zero.
6450 if (!Value->hasValue() ||
6451 (Value->isUnion() && Value->getUnionField() != FD)) {
6452 if (CD->isUnion())
6453 *Value = APValue(FD);
6454 else
6455 // FIXME: This immediately starts the lifetime of all members of
6456 // an anonymous struct. It would be preferable to strictly start
6457 // member lifetime in initialization order.
6458 Success &=
6459 handleDefaultInitValue(Info.Ctx.getRecordType(CD), *Value);
6460 }
6461 // Store Subobject as its parent before updating it for the last element
6462 // in the chain.
6463 if (C == IndirectFieldChain.back())
6464 SubobjectParent = Subobject;
6465 if (!HandleLValueMember(Info, I->getInit(), Subobject, FD))
6466 return false;
6467 if (CD->isUnion())
6468 Value = &Value->getUnionValue();
6469 else {
6470 if (C == IndirectFieldChain.front() && !RD->isUnion())
6471 SkipToField(FD, true);
6472 Value = &Value->getStructField(FD->getFieldIndex());
6473 }
6474 }
6475 } else {
6476 llvm_unreachable("unknown base initializer kind");
6477 }
6478
6479 // Need to override This for implicit field initializers as in this case
6480 // This refers to innermost anonymous struct/union containing initializer,
6481 // not to currently constructed class.
6482 const Expr *Init = I->getInit();
6483 if (Init->isValueDependent()) {
6484 if (!EvaluateDependentExpr(Init, Info))
6485 return false;
6486 } else {
6487 ThisOverrideRAII ThisOverride(*Info.CurrentCall, &SubobjectParent,
6488 isa<CXXDefaultInitExpr>(Init));
6489 FullExpressionRAII InitScope(Info);
6490 if (!EvaluateInPlace(*Value, Info, Subobject, Init) ||
6491 (FD && FD->isBitField() &&
6492 !truncateBitfieldValue(Info, Init, *Value, FD))) {
6493 // If we're checking for a potential constant expression, evaluate all
6494 // initializers even if some of them fail.
6495 if (!Info.noteFailure())
6496 return false;
6497 Success = false;
6498 }
6499 }
6500
6501 // This is the point at which the dynamic type of the object becomes this
6502 // class type.
6503 if (I->isBaseInitializer() && BasesSeen == RD->getNumBases())
6504 EvalObj.finishedConstructingBases();
6505 }
6506
6507 // Default-initialize any remaining fields.
6508 if (!RD->isUnion()) {
6509 for (; FieldIt != RD->field_end(); ++FieldIt) {
6510 if (!FieldIt->isUnnamedBitfield())
6511 Success &= handleDefaultInitValue(
6512 FieldIt->getType(),
6513 Result.getStructField(FieldIt->getFieldIndex()));
6514 }
6515 }
6516
6517 EvalObj.finishedConstructingFields();
6518
6519 return Success &&
6520 EvaluateStmt(Ret, Info, Definition->getBody()) != ESR_Failed &&
6521 LifetimeExtendedScope.destroy();
6522 }
6523
HandleConstructorCall(const Expr * E,const LValue & This,ArrayRef<const Expr * > Args,const CXXConstructorDecl * Definition,EvalInfo & Info,APValue & Result)6524 static bool HandleConstructorCall(const Expr *E, const LValue &This,
6525 ArrayRef<const Expr*> Args,
6526 const CXXConstructorDecl *Definition,
6527 EvalInfo &Info, APValue &Result) {
6528 CallScopeRAII CallScope(Info);
6529 CallRef Call = Info.CurrentCall->createCall(Definition);
6530 if (!EvaluateArgs(Args, Call, Info, Definition))
6531 return false;
6532
6533 return HandleConstructorCall(E, This, Call, Definition, Info, Result) &&
6534 CallScope.destroy();
6535 }
6536
HandleDestructionImpl(EvalInfo & Info,SourceRange CallRange,const LValue & This,APValue & Value,QualType T)6537 static bool HandleDestructionImpl(EvalInfo &Info, SourceRange CallRange,
6538 const LValue &This, APValue &Value,
6539 QualType T) {
6540 // Objects can only be destroyed while they're within their lifetimes.
6541 // FIXME: We have no representation for whether an object of type nullptr_t
6542 // is in its lifetime; it usually doesn't matter. Perhaps we should model it
6543 // as indeterminate instead?
6544 if (Value.isAbsent() && !T->isNullPtrType()) {
6545 APValue Printable;
6546 This.moveInto(Printable);
6547 Info.FFDiag(CallRange.getBegin(),
6548 diag::note_constexpr_destroy_out_of_lifetime)
6549 << Printable.getAsString(Info.Ctx, Info.Ctx.getLValueReferenceType(T));
6550 return false;
6551 }
6552
6553 // Invent an expression for location purposes.
6554 // FIXME: We shouldn't need to do this.
6555 OpaqueValueExpr LocE(CallRange.getBegin(), Info.Ctx.IntTy, VK_PRValue);
6556
6557 // For arrays, destroy elements right-to-left.
6558 if (const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(T)) {
6559 uint64_t Size = CAT->getSize().getZExtValue();
6560 QualType ElemT = CAT->getElementType();
6561
6562 if (!CheckArraySize(Info, CAT, CallRange.getBegin()))
6563 return false;
6564
6565 LValue ElemLV = This;
6566 ElemLV.addArray(Info, &LocE, CAT);
6567 if (!HandleLValueArrayAdjustment(Info, &LocE, ElemLV, ElemT, Size))
6568 return false;
6569
6570 // Ensure that we have actual array elements available to destroy; the
6571 // destructors might mutate the value, so we can't run them on the array
6572 // filler.
6573 if (Size && Size > Value.getArrayInitializedElts())
6574 expandArray(Value, Value.getArraySize() - 1);
6575
6576 for (; Size != 0; --Size) {
6577 APValue &Elem = Value.getArrayInitializedElt(Size - 1);
6578 if (!HandleLValueArrayAdjustment(Info, &LocE, ElemLV, ElemT, -1) ||
6579 !HandleDestructionImpl(Info, CallRange, ElemLV, Elem, ElemT))
6580 return false;
6581 }
6582
6583 // End the lifetime of this array now.
6584 Value = APValue();
6585 return true;
6586 }
6587
6588 const CXXRecordDecl *RD = T->getAsCXXRecordDecl();
6589 if (!RD) {
6590 if (T.isDestructedType()) {
6591 Info.FFDiag(CallRange.getBegin(),
6592 diag::note_constexpr_unsupported_destruction)
6593 << T;
6594 return false;
6595 }
6596
6597 Value = APValue();
6598 return true;
6599 }
6600
6601 if (RD->getNumVBases()) {
6602 Info.FFDiag(CallRange.getBegin(), diag::note_constexpr_virtual_base) << RD;
6603 return false;
6604 }
6605
6606 const CXXDestructorDecl *DD = RD->getDestructor();
6607 if (!DD && !RD->hasTrivialDestructor()) {
6608 Info.FFDiag(CallRange.getBegin());
6609 return false;
6610 }
6611
6612 if (!DD || DD->isTrivial() ||
6613 (RD->isAnonymousStructOrUnion() && RD->isUnion())) {
6614 // A trivial destructor just ends the lifetime of the object. Check for
6615 // this case before checking for a body, because we might not bother
6616 // building a body for a trivial destructor. Note that it doesn't matter
6617 // whether the destructor is constexpr in this case; all trivial
6618 // destructors are constexpr.
6619 //
6620 // If an anonymous union would be destroyed, some enclosing destructor must
6621 // have been explicitly defined, and the anonymous union destruction should
6622 // have no effect.
6623 Value = APValue();
6624 return true;
6625 }
6626
6627 if (!Info.CheckCallLimit(CallRange.getBegin()))
6628 return false;
6629
6630 const FunctionDecl *Definition = nullptr;
6631 const Stmt *Body = DD->getBody(Definition);
6632
6633 if (!CheckConstexprFunction(Info, CallRange.getBegin(), DD, Definition, Body))
6634 return false;
6635
6636 CallStackFrame Frame(Info, CallRange, Definition, &This, /*CallExpr=*/nullptr,
6637 CallRef());
6638
6639 // We're now in the period of destruction of this object.
6640 unsigned BasesLeft = RD->getNumBases();
6641 EvalInfo::EvaluatingDestructorRAII EvalObj(
6642 Info,
6643 ObjectUnderConstruction{This.getLValueBase(), This.Designator.Entries});
6644 if (!EvalObj.DidInsert) {
6645 // C++2a [class.dtor]p19:
6646 // the behavior is undefined if the destructor is invoked for an object
6647 // whose lifetime has ended
6648 // (Note that formally the lifetime ends when the period of destruction
6649 // begins, even though certain uses of the object remain valid until the
6650 // period of destruction ends.)
6651 Info.FFDiag(CallRange.getBegin(), diag::note_constexpr_double_destroy);
6652 return false;
6653 }
6654
6655 // FIXME: Creating an APValue just to hold a nonexistent return value is
6656 // wasteful.
6657 APValue RetVal;
6658 StmtResult Ret = {RetVal, nullptr};
6659 if (EvaluateStmt(Ret, Info, Definition->getBody()) == ESR_Failed)
6660 return false;
6661
6662 // A union destructor does not implicitly destroy its members.
6663 if (RD->isUnion())
6664 return true;
6665
6666 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
6667
6668 // We don't have a good way to iterate fields in reverse, so collect all the
6669 // fields first and then walk them backwards.
6670 SmallVector<FieldDecl*, 16> Fields(RD->fields());
6671 for (const FieldDecl *FD : llvm::reverse(Fields)) {
6672 if (FD->isUnnamedBitfield())
6673 continue;
6674
6675 LValue Subobject = This;
6676 if (!HandleLValueMember(Info, &LocE, Subobject, FD, &Layout))
6677 return false;
6678
6679 APValue *SubobjectValue = &Value.getStructField(FD->getFieldIndex());
6680 if (!HandleDestructionImpl(Info, CallRange, Subobject, *SubobjectValue,
6681 FD->getType()))
6682 return false;
6683 }
6684
6685 if (BasesLeft != 0)
6686 EvalObj.startedDestroyingBases();
6687
6688 // Destroy base classes in reverse order.
6689 for (const CXXBaseSpecifier &Base : llvm::reverse(RD->bases())) {
6690 --BasesLeft;
6691
6692 QualType BaseType = Base.getType();
6693 LValue Subobject = This;
6694 if (!HandleLValueDirectBase(Info, &LocE, Subobject, RD,
6695 BaseType->getAsCXXRecordDecl(), &Layout))
6696 return false;
6697
6698 APValue *SubobjectValue = &Value.getStructBase(BasesLeft);
6699 if (!HandleDestructionImpl(Info, CallRange, Subobject, *SubobjectValue,
6700 BaseType))
6701 return false;
6702 }
6703 assert(BasesLeft == 0 && "NumBases was wrong?");
6704
6705 // The period of destruction ends now. The object is gone.
6706 Value = APValue();
6707 return true;
6708 }
6709
6710 namespace {
6711 struct DestroyObjectHandler {
6712 EvalInfo &Info;
6713 const Expr *E;
6714 const LValue &This;
6715 const AccessKinds AccessKind;
6716
6717 typedef bool result_type;
failed__anonbf0ddd821511::DestroyObjectHandler6718 bool failed() { return false; }
found__anonbf0ddd821511::DestroyObjectHandler6719 bool found(APValue &Subobj, QualType SubobjType) {
6720 return HandleDestructionImpl(Info, E->getSourceRange(), This, Subobj,
6721 SubobjType);
6722 }
found__anonbf0ddd821511::DestroyObjectHandler6723 bool found(APSInt &Value, QualType SubobjType) {
6724 Info.FFDiag(E, diag::note_constexpr_destroy_complex_elem);
6725 return false;
6726 }
found__anonbf0ddd821511::DestroyObjectHandler6727 bool found(APFloat &Value, QualType SubobjType) {
6728 Info.FFDiag(E, diag::note_constexpr_destroy_complex_elem);
6729 return false;
6730 }
6731 };
6732 }
6733
6734 /// Perform a destructor or pseudo-destructor call on the given object, which
6735 /// might in general not be a complete object.
HandleDestruction(EvalInfo & Info,const Expr * E,const LValue & This,QualType ThisType)6736 static bool HandleDestruction(EvalInfo &Info, const Expr *E,
6737 const LValue &This, QualType ThisType) {
6738 CompleteObject Obj = findCompleteObject(Info, E, AK_Destroy, This, ThisType);
6739 DestroyObjectHandler Handler = {Info, E, This, AK_Destroy};
6740 return Obj && findSubobject(Info, E, Obj, This.Designator, Handler);
6741 }
6742
6743 /// Destroy and end the lifetime of the given complete object.
HandleDestruction(EvalInfo & Info,SourceLocation Loc,APValue::LValueBase LVBase,APValue & Value,QualType T)6744 static bool HandleDestruction(EvalInfo &Info, SourceLocation Loc,
6745 APValue::LValueBase LVBase, APValue &Value,
6746 QualType T) {
6747 // If we've had an unmodeled side-effect, we can't rely on mutable state
6748 // (such as the object we're about to destroy) being correct.
6749 if (Info.EvalStatus.HasSideEffects)
6750 return false;
6751
6752 LValue LV;
6753 LV.set({LVBase});
6754 return HandleDestructionImpl(Info, Loc, LV, Value, T);
6755 }
6756
6757 /// Perform a call to 'operator new' or to `__builtin_operator_new'.
HandleOperatorNewCall(EvalInfo & Info,const CallExpr * E,LValue & Result)6758 static bool HandleOperatorNewCall(EvalInfo &Info, const CallExpr *E,
6759 LValue &Result) {
6760 if (Info.checkingPotentialConstantExpression() ||
6761 Info.SpeculativeEvaluationDepth)
6762 return false;
6763
6764 // This is permitted only within a call to std::allocator<T>::allocate.
6765 auto Caller = Info.getStdAllocatorCaller("allocate");
6766 if (!Caller) {
6767 Info.FFDiag(E->getExprLoc(), Info.getLangOpts().CPlusPlus20
6768 ? diag::note_constexpr_new_untyped
6769 : diag::note_constexpr_new);
6770 return false;
6771 }
6772
6773 QualType ElemType = Caller.ElemType;
6774 if (ElemType->isIncompleteType() || ElemType->isFunctionType()) {
6775 Info.FFDiag(E->getExprLoc(),
6776 diag::note_constexpr_new_not_complete_object_type)
6777 << (ElemType->isIncompleteType() ? 0 : 1) << ElemType;
6778 return false;
6779 }
6780
6781 APSInt ByteSize;
6782 if (!EvaluateInteger(E->getArg(0), ByteSize, Info))
6783 return false;
6784 bool IsNothrow = false;
6785 for (unsigned I = 1, N = E->getNumArgs(); I != N; ++I) {
6786 EvaluateIgnoredValue(Info, E->getArg(I));
6787 IsNothrow |= E->getType()->isNothrowT();
6788 }
6789
6790 CharUnits ElemSize;
6791 if (!HandleSizeof(Info, E->getExprLoc(), ElemType, ElemSize))
6792 return false;
6793 APInt Size, Remainder;
6794 APInt ElemSizeAP(ByteSize.getBitWidth(), ElemSize.getQuantity());
6795 APInt::udivrem(ByteSize, ElemSizeAP, Size, Remainder);
6796 if (Remainder != 0) {
6797 // This likely indicates a bug in the implementation of 'std::allocator'.
6798 Info.FFDiag(E->getExprLoc(), diag::note_constexpr_operator_new_bad_size)
6799 << ByteSize << APSInt(ElemSizeAP, true) << ElemType;
6800 return false;
6801 }
6802
6803 if (!Info.CheckArraySize(E->getBeginLoc(), ByteSize.getActiveBits(),
6804 Size.getZExtValue(), /*Diag=*/!IsNothrow)) {
6805 if (IsNothrow) {
6806 Result.setNull(Info.Ctx, E->getType());
6807 return true;
6808 }
6809 return false;
6810 }
6811
6812 QualType AllocType = Info.Ctx.getConstantArrayType(
6813 ElemType, Size, nullptr, ArraySizeModifier::Normal, 0);
6814 APValue *Val = Info.createHeapAlloc(E, AllocType, Result);
6815 *Val = APValue(APValue::UninitArray(), 0, Size.getZExtValue());
6816 Result.addArray(Info, E, cast<ConstantArrayType>(AllocType));
6817 return true;
6818 }
6819
hasVirtualDestructor(QualType T)6820 static bool hasVirtualDestructor(QualType T) {
6821 if (CXXRecordDecl *RD = T->getAsCXXRecordDecl())
6822 if (CXXDestructorDecl *DD = RD->getDestructor())
6823 return DD->isVirtual();
6824 return false;
6825 }
6826
getVirtualOperatorDelete(QualType T)6827 static const FunctionDecl *getVirtualOperatorDelete(QualType T) {
6828 if (CXXRecordDecl *RD = T->getAsCXXRecordDecl())
6829 if (CXXDestructorDecl *DD = RD->getDestructor())
6830 return DD->isVirtual() ? DD->getOperatorDelete() : nullptr;
6831 return nullptr;
6832 }
6833
6834 /// Check that the given object is a suitable pointer to a heap allocation that
6835 /// still exists and is of the right kind for the purpose of a deletion.
6836 ///
6837 /// On success, returns the heap allocation to deallocate. On failure, produces
6838 /// a diagnostic and returns std::nullopt.
CheckDeleteKind(EvalInfo & Info,const Expr * E,const LValue & Pointer,DynAlloc::Kind DeallocKind)6839 static std::optional<DynAlloc *> CheckDeleteKind(EvalInfo &Info, const Expr *E,
6840 const LValue &Pointer,
6841 DynAlloc::Kind DeallocKind) {
6842 auto PointerAsString = [&] {
6843 return Pointer.toString(Info.Ctx, Info.Ctx.VoidPtrTy);
6844 };
6845
6846 DynamicAllocLValue DA = Pointer.Base.dyn_cast<DynamicAllocLValue>();
6847 if (!DA) {
6848 Info.FFDiag(E, diag::note_constexpr_delete_not_heap_alloc)
6849 << PointerAsString();
6850 if (Pointer.Base)
6851 NoteLValueLocation(Info, Pointer.Base);
6852 return std::nullopt;
6853 }
6854
6855 std::optional<DynAlloc *> Alloc = Info.lookupDynamicAlloc(DA);
6856 if (!Alloc) {
6857 Info.FFDiag(E, diag::note_constexpr_double_delete);
6858 return std::nullopt;
6859 }
6860
6861 if (DeallocKind != (*Alloc)->getKind()) {
6862 QualType AllocType = Pointer.Base.getDynamicAllocType();
6863 Info.FFDiag(E, diag::note_constexpr_new_delete_mismatch)
6864 << DeallocKind << (*Alloc)->getKind() << AllocType;
6865 NoteLValueLocation(Info, Pointer.Base);
6866 return std::nullopt;
6867 }
6868
6869 bool Subobject = false;
6870 if (DeallocKind == DynAlloc::New) {
6871 Subobject = Pointer.Designator.MostDerivedPathLength != 0 ||
6872 Pointer.Designator.isOnePastTheEnd();
6873 } else {
6874 Subobject = Pointer.Designator.Entries.size() != 1 ||
6875 Pointer.Designator.Entries[0].getAsArrayIndex() != 0;
6876 }
6877 if (Subobject) {
6878 Info.FFDiag(E, diag::note_constexpr_delete_subobject)
6879 << PointerAsString() << Pointer.Designator.isOnePastTheEnd();
6880 return std::nullopt;
6881 }
6882
6883 return Alloc;
6884 }
6885
6886 // Perform a call to 'operator delete' or '__builtin_operator_delete'.
HandleOperatorDeleteCall(EvalInfo & Info,const CallExpr * E)6887 bool HandleOperatorDeleteCall(EvalInfo &Info, const CallExpr *E) {
6888 if (Info.checkingPotentialConstantExpression() ||
6889 Info.SpeculativeEvaluationDepth)
6890 return false;
6891
6892 // This is permitted only within a call to std::allocator<T>::deallocate.
6893 if (!Info.getStdAllocatorCaller("deallocate")) {
6894 Info.FFDiag(E->getExprLoc());
6895 return true;
6896 }
6897
6898 LValue Pointer;
6899 if (!EvaluatePointer(E->getArg(0), Pointer, Info))
6900 return false;
6901 for (unsigned I = 1, N = E->getNumArgs(); I != N; ++I)
6902 EvaluateIgnoredValue(Info, E->getArg(I));
6903
6904 if (Pointer.Designator.Invalid)
6905 return false;
6906
6907 // Deleting a null pointer would have no effect, but it's not permitted by
6908 // std::allocator<T>::deallocate's contract.
6909 if (Pointer.isNullPointer()) {
6910 Info.CCEDiag(E->getExprLoc(), diag::note_constexpr_deallocate_null);
6911 return true;
6912 }
6913
6914 if (!CheckDeleteKind(Info, E, Pointer, DynAlloc::StdAllocator))
6915 return false;
6916
6917 Info.HeapAllocs.erase(Pointer.Base.get<DynamicAllocLValue>());
6918 return true;
6919 }
6920
6921 //===----------------------------------------------------------------------===//
6922 // Generic Evaluation
6923 //===----------------------------------------------------------------------===//
6924 namespace {
6925
6926 class BitCastBuffer {
6927 // FIXME: We're going to need bit-level granularity when we support
6928 // bit-fields.
6929 // FIXME: Its possible under the C++ standard for 'char' to not be 8 bits, but
6930 // we don't support a host or target where that is the case. Still, we should
6931 // use a more generic type in case we ever do.
6932 SmallVector<std::optional<unsigned char>, 32> Bytes;
6933
6934 static_assert(std::numeric_limits<unsigned char>::digits >= 8,
6935 "Need at least 8 bit unsigned char");
6936
6937 bool TargetIsLittleEndian;
6938
6939 public:
BitCastBuffer(CharUnits Width,bool TargetIsLittleEndian)6940 BitCastBuffer(CharUnits Width, bool TargetIsLittleEndian)
6941 : Bytes(Width.getQuantity()),
6942 TargetIsLittleEndian(TargetIsLittleEndian) {}
6943
readObject(CharUnits Offset,CharUnits Width,SmallVectorImpl<unsigned char> & Output) const6944 [[nodiscard]] bool readObject(CharUnits Offset, CharUnits Width,
6945 SmallVectorImpl<unsigned char> &Output) const {
6946 for (CharUnits I = Offset, E = Offset + Width; I != E; ++I) {
6947 // If a byte of an integer is uninitialized, then the whole integer is
6948 // uninitialized.
6949 if (!Bytes[I.getQuantity()])
6950 return false;
6951 Output.push_back(*Bytes[I.getQuantity()]);
6952 }
6953 if (llvm::sys::IsLittleEndianHost != TargetIsLittleEndian)
6954 std::reverse(Output.begin(), Output.end());
6955 return true;
6956 }
6957
writeObject(CharUnits Offset,SmallVectorImpl<unsigned char> & Input)6958 void writeObject(CharUnits Offset, SmallVectorImpl<unsigned char> &Input) {
6959 if (llvm::sys::IsLittleEndianHost != TargetIsLittleEndian)
6960 std::reverse(Input.begin(), Input.end());
6961
6962 size_t Index = 0;
6963 for (unsigned char Byte : Input) {
6964 assert(!Bytes[Offset.getQuantity() + Index] && "overwriting a byte?");
6965 Bytes[Offset.getQuantity() + Index] = Byte;
6966 ++Index;
6967 }
6968 }
6969
size()6970 size_t size() { return Bytes.size(); }
6971 };
6972
6973 /// Traverse an APValue to produce an BitCastBuffer, emulating how the current
6974 /// target would represent the value at runtime.
6975 class APValueToBufferConverter {
6976 EvalInfo &Info;
6977 BitCastBuffer Buffer;
6978 const CastExpr *BCE;
6979
APValueToBufferConverter(EvalInfo & Info,CharUnits ObjectWidth,const CastExpr * BCE)6980 APValueToBufferConverter(EvalInfo &Info, CharUnits ObjectWidth,
6981 const CastExpr *BCE)
6982 : Info(Info),
6983 Buffer(ObjectWidth, Info.Ctx.getTargetInfo().isLittleEndian()),
6984 BCE(BCE) {}
6985
visit(const APValue & Val,QualType Ty)6986 bool visit(const APValue &Val, QualType Ty) {
6987 return visit(Val, Ty, CharUnits::fromQuantity(0));
6988 }
6989
6990 // Write out Val with type Ty into Buffer starting at Offset.
visit(const APValue & Val,QualType Ty,CharUnits Offset)6991 bool visit(const APValue &Val, QualType Ty, CharUnits Offset) {
6992 assert((size_t)Offset.getQuantity() <= Buffer.size());
6993
6994 // As a special case, nullptr_t has an indeterminate value.
6995 if (Ty->isNullPtrType())
6996 return true;
6997
6998 // Dig through Src to find the byte at SrcOffset.
6999 switch (Val.getKind()) {
7000 case APValue::Indeterminate:
7001 case APValue::None:
7002 return true;
7003
7004 case APValue::Int:
7005 return visitInt(Val.getInt(), Ty, Offset);
7006 case APValue::Float:
7007 return visitFloat(Val.getFloat(), Ty, Offset);
7008 case APValue::Array:
7009 return visitArray(Val, Ty, Offset);
7010 case APValue::Struct:
7011 return visitRecord(Val, Ty, Offset);
7012 case APValue::Vector:
7013 return visitVector(Val, Ty, Offset);
7014
7015 case APValue::ComplexInt:
7016 case APValue::ComplexFloat:
7017 case APValue::FixedPoint:
7018 // FIXME: We should support these.
7019
7020 case APValue::Union:
7021 case APValue::MemberPointer:
7022 case APValue::AddrLabelDiff: {
7023 Info.FFDiag(BCE->getBeginLoc(),
7024 diag::note_constexpr_bit_cast_unsupported_type)
7025 << Ty;
7026 return false;
7027 }
7028
7029 case APValue::LValue:
7030 llvm_unreachable("LValue subobject in bit_cast?");
7031 }
7032 llvm_unreachable("Unhandled APValue::ValueKind");
7033 }
7034
visitRecord(const APValue & Val,QualType Ty,CharUnits Offset)7035 bool visitRecord(const APValue &Val, QualType Ty, CharUnits Offset) {
7036 const RecordDecl *RD = Ty->getAsRecordDecl();
7037 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
7038
7039 // Visit the base classes.
7040 if (auto *CXXRD = dyn_cast<CXXRecordDecl>(RD)) {
7041 for (size_t I = 0, E = CXXRD->getNumBases(); I != E; ++I) {
7042 const CXXBaseSpecifier &BS = CXXRD->bases_begin()[I];
7043 CXXRecordDecl *BaseDecl = BS.getType()->getAsCXXRecordDecl();
7044
7045 if (!visitRecord(Val.getStructBase(I), BS.getType(),
7046 Layout.getBaseClassOffset(BaseDecl) + Offset))
7047 return false;
7048 }
7049 }
7050
7051 // Visit the fields.
7052 unsigned FieldIdx = 0;
7053 for (FieldDecl *FD : RD->fields()) {
7054 if (FD->isBitField()) {
7055 Info.FFDiag(BCE->getBeginLoc(),
7056 diag::note_constexpr_bit_cast_unsupported_bitfield);
7057 return false;
7058 }
7059
7060 uint64_t FieldOffsetBits = Layout.getFieldOffset(FieldIdx);
7061
7062 assert(FieldOffsetBits % Info.Ctx.getCharWidth() == 0 &&
7063 "only bit-fields can have sub-char alignment");
7064 CharUnits FieldOffset =
7065 Info.Ctx.toCharUnitsFromBits(FieldOffsetBits) + Offset;
7066 QualType FieldTy = FD->getType();
7067 if (!visit(Val.getStructField(FieldIdx), FieldTy, FieldOffset))
7068 return false;
7069 ++FieldIdx;
7070 }
7071
7072 return true;
7073 }
7074
visitArray(const APValue & Val,QualType Ty,CharUnits Offset)7075 bool visitArray(const APValue &Val, QualType Ty, CharUnits Offset) {
7076 const auto *CAT =
7077 dyn_cast_or_null<ConstantArrayType>(Ty->getAsArrayTypeUnsafe());
7078 if (!CAT)
7079 return false;
7080
7081 CharUnits ElemWidth = Info.Ctx.getTypeSizeInChars(CAT->getElementType());
7082 unsigned NumInitializedElts = Val.getArrayInitializedElts();
7083 unsigned ArraySize = Val.getArraySize();
7084 // First, initialize the initialized elements.
7085 for (unsigned I = 0; I != NumInitializedElts; ++I) {
7086 const APValue &SubObj = Val.getArrayInitializedElt(I);
7087 if (!visit(SubObj, CAT->getElementType(), Offset + I * ElemWidth))
7088 return false;
7089 }
7090
7091 // Next, initialize the rest of the array using the filler.
7092 if (Val.hasArrayFiller()) {
7093 const APValue &Filler = Val.getArrayFiller();
7094 for (unsigned I = NumInitializedElts; I != ArraySize; ++I) {
7095 if (!visit(Filler, CAT->getElementType(), Offset + I * ElemWidth))
7096 return false;
7097 }
7098 }
7099
7100 return true;
7101 }
7102
visitVector(const APValue & Val,QualType Ty,CharUnits Offset)7103 bool visitVector(const APValue &Val, QualType Ty, CharUnits Offset) {
7104 const VectorType *VTy = Ty->castAs<VectorType>();
7105 QualType EltTy = VTy->getElementType();
7106 unsigned NElts = VTy->getNumElements();
7107 unsigned EltSize =
7108 VTy->isExtVectorBoolType() ? 1 : Info.Ctx.getTypeSize(EltTy);
7109
7110 if ((NElts * EltSize) % Info.Ctx.getCharWidth() != 0) {
7111 // The vector's size in bits is not a multiple of the target's byte size,
7112 // so its layout is unspecified. For now, we'll simply treat these cases
7113 // as unsupported (this should only be possible with OpenCL bool vectors
7114 // whose element count isn't a multiple of the byte size).
7115 Info.FFDiag(BCE->getBeginLoc(),
7116 diag::note_constexpr_bit_cast_invalid_vector)
7117 << Ty.getCanonicalType() << EltSize << NElts
7118 << Info.Ctx.getCharWidth();
7119 return false;
7120 }
7121
7122 if (EltTy->isRealFloatingType() && &Info.Ctx.getFloatTypeSemantics(EltTy) ==
7123 &APFloat::x87DoubleExtended()) {
7124 // The layout for x86_fp80 vectors seems to be handled very inconsistently
7125 // by both clang and LLVM, so for now we won't allow bit_casts involving
7126 // it in a constexpr context.
7127 Info.FFDiag(BCE->getBeginLoc(),
7128 diag::note_constexpr_bit_cast_unsupported_type)
7129 << EltTy;
7130 return false;
7131 }
7132
7133 if (VTy->isExtVectorBoolType()) {
7134 // Special handling for OpenCL bool vectors:
7135 // Since these vectors are stored as packed bits, but we can't write
7136 // individual bits to the BitCastBuffer, we'll buffer all of the elements
7137 // together into an appropriately sized APInt and write them all out at
7138 // once. Because we don't accept vectors where NElts * EltSize isn't a
7139 // multiple of the char size, there will be no padding space, so we don't
7140 // have to worry about writing data which should have been left
7141 // uninitialized.
7142 bool BigEndian = Info.Ctx.getTargetInfo().isBigEndian();
7143
7144 llvm::APInt Res = llvm::APInt::getZero(NElts);
7145 for (unsigned I = 0; I < NElts; ++I) {
7146 const llvm::APSInt &EltAsInt = Val.getVectorElt(I).getInt();
7147 assert(EltAsInt.isUnsigned() && EltAsInt.getBitWidth() == 1 &&
7148 "bool vector element must be 1-bit unsigned integer!");
7149
7150 Res.insertBits(EltAsInt, BigEndian ? (NElts - I - 1) : I);
7151 }
7152
7153 SmallVector<uint8_t, 8> Bytes(NElts / 8);
7154 llvm::StoreIntToMemory(Res, &*Bytes.begin(), NElts / 8);
7155 Buffer.writeObject(Offset, Bytes);
7156 } else {
7157 // Iterate over each of the elements and write them out to the buffer at
7158 // the appropriate offset.
7159 CharUnits EltSizeChars = Info.Ctx.getTypeSizeInChars(EltTy);
7160 for (unsigned I = 0; I < NElts; ++I) {
7161 if (!visit(Val.getVectorElt(I), EltTy, Offset + I * EltSizeChars))
7162 return false;
7163 }
7164 }
7165
7166 return true;
7167 }
7168
visitInt(const APSInt & Val,QualType Ty,CharUnits Offset)7169 bool visitInt(const APSInt &Val, QualType Ty, CharUnits Offset) {
7170 APSInt AdjustedVal = Val;
7171 unsigned Width = AdjustedVal.getBitWidth();
7172 if (Ty->isBooleanType()) {
7173 Width = Info.Ctx.getTypeSize(Ty);
7174 AdjustedVal = AdjustedVal.extend(Width);
7175 }
7176
7177 SmallVector<uint8_t, 8> Bytes(Width / 8);
7178 llvm::StoreIntToMemory(AdjustedVal, &*Bytes.begin(), Width / 8);
7179 Buffer.writeObject(Offset, Bytes);
7180 return true;
7181 }
7182
visitFloat(const APFloat & Val,QualType Ty,CharUnits Offset)7183 bool visitFloat(const APFloat &Val, QualType Ty, CharUnits Offset) {
7184 APSInt AsInt(Val.bitcastToAPInt());
7185 return visitInt(AsInt, Ty, Offset);
7186 }
7187
7188 public:
7189 static std::optional<BitCastBuffer>
convert(EvalInfo & Info,const APValue & Src,const CastExpr * BCE)7190 convert(EvalInfo &Info, const APValue &Src, const CastExpr *BCE) {
7191 CharUnits DstSize = Info.Ctx.getTypeSizeInChars(BCE->getType());
7192 APValueToBufferConverter Converter(Info, DstSize, BCE);
7193 if (!Converter.visit(Src, BCE->getSubExpr()->getType()))
7194 return std::nullopt;
7195 return Converter.Buffer;
7196 }
7197 };
7198
7199 /// Write an BitCastBuffer into an APValue.
7200 class BufferToAPValueConverter {
7201 EvalInfo &Info;
7202 const BitCastBuffer &Buffer;
7203 const CastExpr *BCE;
7204
BufferToAPValueConverter(EvalInfo & Info,const BitCastBuffer & Buffer,const CastExpr * BCE)7205 BufferToAPValueConverter(EvalInfo &Info, const BitCastBuffer &Buffer,
7206 const CastExpr *BCE)
7207 : Info(Info), Buffer(Buffer), BCE(BCE) {}
7208
7209 // Emit an unsupported bit_cast type error. Sema refuses to build a bit_cast
7210 // with an invalid type, so anything left is a deficiency on our part (FIXME).
7211 // Ideally this will be unreachable.
unsupportedType(QualType Ty)7212 std::nullopt_t unsupportedType(QualType Ty) {
7213 Info.FFDiag(BCE->getBeginLoc(),
7214 diag::note_constexpr_bit_cast_unsupported_type)
7215 << Ty;
7216 return std::nullopt;
7217 }
7218
unrepresentableValue(QualType Ty,const APSInt & Val)7219 std::nullopt_t unrepresentableValue(QualType Ty, const APSInt &Val) {
7220 Info.FFDiag(BCE->getBeginLoc(),
7221 diag::note_constexpr_bit_cast_unrepresentable_value)
7222 << Ty << toString(Val, /*Radix=*/10);
7223 return std::nullopt;
7224 }
7225
visit(const BuiltinType * T,CharUnits Offset,const EnumType * EnumSugar=nullptr)7226 std::optional<APValue> visit(const BuiltinType *T, CharUnits Offset,
7227 const EnumType *EnumSugar = nullptr) {
7228 if (T->isNullPtrType()) {
7229 uint64_t NullValue = Info.Ctx.getTargetNullPointerValue(QualType(T, 0));
7230 return APValue((Expr *)nullptr,
7231 /*Offset=*/CharUnits::fromQuantity(NullValue),
7232 APValue::NoLValuePath{}, /*IsNullPtr=*/true);
7233 }
7234
7235 CharUnits SizeOf = Info.Ctx.getTypeSizeInChars(T);
7236
7237 // Work around floating point types that contain unused padding bytes. This
7238 // is really just `long double` on x86, which is the only fundamental type
7239 // with padding bytes.
7240 if (T->isRealFloatingType()) {
7241 const llvm::fltSemantics &Semantics =
7242 Info.Ctx.getFloatTypeSemantics(QualType(T, 0));
7243 unsigned NumBits = llvm::APFloatBase::getSizeInBits(Semantics);
7244 assert(NumBits % 8 == 0);
7245 CharUnits NumBytes = CharUnits::fromQuantity(NumBits / 8);
7246 if (NumBytes != SizeOf)
7247 SizeOf = NumBytes;
7248 }
7249
7250 SmallVector<uint8_t, 8> Bytes;
7251 if (!Buffer.readObject(Offset, SizeOf, Bytes)) {
7252 // If this is std::byte or unsigned char, then its okay to store an
7253 // indeterminate value.
7254 bool IsStdByte = EnumSugar && EnumSugar->isStdByteType();
7255 bool IsUChar =
7256 !EnumSugar && (T->isSpecificBuiltinType(BuiltinType::UChar) ||
7257 T->isSpecificBuiltinType(BuiltinType::Char_U));
7258 if (!IsStdByte && !IsUChar) {
7259 QualType DisplayType(EnumSugar ? (const Type *)EnumSugar : T, 0);
7260 Info.FFDiag(BCE->getExprLoc(),
7261 diag::note_constexpr_bit_cast_indet_dest)
7262 << DisplayType << Info.Ctx.getLangOpts().CharIsSigned;
7263 return std::nullopt;
7264 }
7265
7266 return APValue::IndeterminateValue();
7267 }
7268
7269 APSInt Val(SizeOf.getQuantity() * Info.Ctx.getCharWidth(), true);
7270 llvm::LoadIntFromMemory(Val, &*Bytes.begin(), Bytes.size());
7271
7272 if (T->isIntegralOrEnumerationType()) {
7273 Val.setIsSigned(T->isSignedIntegerOrEnumerationType());
7274
7275 unsigned IntWidth = Info.Ctx.getIntWidth(QualType(T, 0));
7276 if (IntWidth != Val.getBitWidth()) {
7277 APSInt Truncated = Val.trunc(IntWidth);
7278 if (Truncated.extend(Val.getBitWidth()) != Val)
7279 return unrepresentableValue(QualType(T, 0), Val);
7280 Val = Truncated;
7281 }
7282
7283 return APValue(Val);
7284 }
7285
7286 if (T->isRealFloatingType()) {
7287 const llvm::fltSemantics &Semantics =
7288 Info.Ctx.getFloatTypeSemantics(QualType(T, 0));
7289 return APValue(APFloat(Semantics, Val));
7290 }
7291
7292 return unsupportedType(QualType(T, 0));
7293 }
7294
visit(const RecordType * RTy,CharUnits Offset)7295 std::optional<APValue> visit(const RecordType *RTy, CharUnits Offset) {
7296 const RecordDecl *RD = RTy->getAsRecordDecl();
7297 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
7298
7299 unsigned NumBases = 0;
7300 if (auto *CXXRD = dyn_cast<CXXRecordDecl>(RD))
7301 NumBases = CXXRD->getNumBases();
7302
7303 APValue ResultVal(APValue::UninitStruct(), NumBases,
7304 std::distance(RD->field_begin(), RD->field_end()));
7305
7306 // Visit the base classes.
7307 if (auto *CXXRD = dyn_cast<CXXRecordDecl>(RD)) {
7308 for (size_t I = 0, E = CXXRD->getNumBases(); I != E; ++I) {
7309 const CXXBaseSpecifier &BS = CXXRD->bases_begin()[I];
7310 CXXRecordDecl *BaseDecl = BS.getType()->getAsCXXRecordDecl();
7311 if (BaseDecl->isEmpty() ||
7312 Info.Ctx.getASTRecordLayout(BaseDecl).getNonVirtualSize().isZero())
7313 continue;
7314
7315 std::optional<APValue> SubObj = visitType(
7316 BS.getType(), Layout.getBaseClassOffset(BaseDecl) + Offset);
7317 if (!SubObj)
7318 return std::nullopt;
7319 ResultVal.getStructBase(I) = *SubObj;
7320 }
7321 }
7322
7323 // Visit the fields.
7324 unsigned FieldIdx = 0;
7325 for (FieldDecl *FD : RD->fields()) {
7326 // FIXME: We don't currently support bit-fields. A lot of the logic for
7327 // this is in CodeGen, so we need to factor it around.
7328 if (FD->isBitField()) {
7329 Info.FFDiag(BCE->getBeginLoc(),
7330 diag::note_constexpr_bit_cast_unsupported_bitfield);
7331 return std::nullopt;
7332 }
7333
7334 uint64_t FieldOffsetBits = Layout.getFieldOffset(FieldIdx);
7335 assert(FieldOffsetBits % Info.Ctx.getCharWidth() == 0);
7336
7337 CharUnits FieldOffset =
7338 CharUnits::fromQuantity(FieldOffsetBits / Info.Ctx.getCharWidth()) +
7339 Offset;
7340 QualType FieldTy = FD->getType();
7341 std::optional<APValue> SubObj = visitType(FieldTy, FieldOffset);
7342 if (!SubObj)
7343 return std::nullopt;
7344 ResultVal.getStructField(FieldIdx) = *SubObj;
7345 ++FieldIdx;
7346 }
7347
7348 return ResultVal;
7349 }
7350
visit(const EnumType * Ty,CharUnits Offset)7351 std::optional<APValue> visit(const EnumType *Ty, CharUnits Offset) {
7352 QualType RepresentationType = Ty->getDecl()->getIntegerType();
7353 assert(!RepresentationType.isNull() &&
7354 "enum forward decl should be caught by Sema");
7355 const auto *AsBuiltin =
7356 RepresentationType.getCanonicalType()->castAs<BuiltinType>();
7357 // Recurse into the underlying type. Treat std::byte transparently as
7358 // unsigned char.
7359 return visit(AsBuiltin, Offset, /*EnumTy=*/Ty);
7360 }
7361
visit(const ConstantArrayType * Ty,CharUnits Offset)7362 std::optional<APValue> visit(const ConstantArrayType *Ty, CharUnits Offset) {
7363 size_t Size = Ty->getSize().getLimitedValue();
7364 CharUnits ElementWidth = Info.Ctx.getTypeSizeInChars(Ty->getElementType());
7365
7366 APValue ArrayValue(APValue::UninitArray(), Size, Size);
7367 for (size_t I = 0; I != Size; ++I) {
7368 std::optional<APValue> ElementValue =
7369 visitType(Ty->getElementType(), Offset + I * ElementWidth);
7370 if (!ElementValue)
7371 return std::nullopt;
7372 ArrayValue.getArrayInitializedElt(I) = std::move(*ElementValue);
7373 }
7374
7375 return ArrayValue;
7376 }
7377
visit(const VectorType * VTy,CharUnits Offset)7378 std::optional<APValue> visit(const VectorType *VTy, CharUnits Offset) {
7379 QualType EltTy = VTy->getElementType();
7380 unsigned NElts = VTy->getNumElements();
7381 unsigned EltSize =
7382 VTy->isExtVectorBoolType() ? 1 : Info.Ctx.getTypeSize(EltTy);
7383
7384 if ((NElts * EltSize) % Info.Ctx.getCharWidth() != 0) {
7385 // The vector's size in bits is not a multiple of the target's byte size,
7386 // so its layout is unspecified. For now, we'll simply treat these cases
7387 // as unsupported (this should only be possible with OpenCL bool vectors
7388 // whose element count isn't a multiple of the byte size).
7389 Info.FFDiag(BCE->getBeginLoc(),
7390 diag::note_constexpr_bit_cast_invalid_vector)
7391 << QualType(VTy, 0) << EltSize << NElts << Info.Ctx.getCharWidth();
7392 return std::nullopt;
7393 }
7394
7395 if (EltTy->isRealFloatingType() && &Info.Ctx.getFloatTypeSemantics(EltTy) ==
7396 &APFloat::x87DoubleExtended()) {
7397 // The layout for x86_fp80 vectors seems to be handled very inconsistently
7398 // by both clang and LLVM, so for now we won't allow bit_casts involving
7399 // it in a constexpr context.
7400 Info.FFDiag(BCE->getBeginLoc(),
7401 diag::note_constexpr_bit_cast_unsupported_type)
7402 << EltTy;
7403 return std::nullopt;
7404 }
7405
7406 SmallVector<APValue, 4> Elts;
7407 Elts.reserve(NElts);
7408 if (VTy->isExtVectorBoolType()) {
7409 // Special handling for OpenCL bool vectors:
7410 // Since these vectors are stored as packed bits, but we can't read
7411 // individual bits from the BitCastBuffer, we'll buffer all of the
7412 // elements together into an appropriately sized APInt and write them all
7413 // out at once. Because we don't accept vectors where NElts * EltSize
7414 // isn't a multiple of the char size, there will be no padding space, so
7415 // we don't have to worry about reading any padding data which didn't
7416 // actually need to be accessed.
7417 bool BigEndian = Info.Ctx.getTargetInfo().isBigEndian();
7418
7419 SmallVector<uint8_t, 8> Bytes;
7420 Bytes.reserve(NElts / 8);
7421 if (!Buffer.readObject(Offset, CharUnits::fromQuantity(NElts / 8), Bytes))
7422 return std::nullopt;
7423
7424 APSInt SValInt(NElts, true);
7425 llvm::LoadIntFromMemory(SValInt, &*Bytes.begin(), Bytes.size());
7426
7427 for (unsigned I = 0; I < NElts; ++I) {
7428 llvm::APInt Elt =
7429 SValInt.extractBits(1, (BigEndian ? NElts - I - 1 : I) * EltSize);
7430 Elts.emplace_back(
7431 APSInt(std::move(Elt), !EltTy->isSignedIntegerType()));
7432 }
7433 } else {
7434 // Iterate over each of the elements and read them from the buffer at
7435 // the appropriate offset.
7436 CharUnits EltSizeChars = Info.Ctx.getTypeSizeInChars(EltTy);
7437 for (unsigned I = 0; I < NElts; ++I) {
7438 std::optional<APValue> EltValue =
7439 visitType(EltTy, Offset + I * EltSizeChars);
7440 if (!EltValue)
7441 return std::nullopt;
7442 Elts.push_back(std::move(*EltValue));
7443 }
7444 }
7445
7446 return APValue(Elts.data(), Elts.size());
7447 }
7448
visit(const Type * Ty,CharUnits Offset)7449 std::optional<APValue> visit(const Type *Ty, CharUnits Offset) {
7450 return unsupportedType(QualType(Ty, 0));
7451 }
7452
visitType(QualType Ty,CharUnits Offset)7453 std::optional<APValue> visitType(QualType Ty, CharUnits Offset) {
7454 QualType Can = Ty.getCanonicalType();
7455
7456 switch (Can->getTypeClass()) {
7457 #define TYPE(Class, Base) \
7458 case Type::Class: \
7459 return visit(cast<Class##Type>(Can.getTypePtr()), Offset);
7460 #define ABSTRACT_TYPE(Class, Base)
7461 #define NON_CANONICAL_TYPE(Class, Base) \
7462 case Type::Class: \
7463 llvm_unreachable("non-canonical type should be impossible!");
7464 #define DEPENDENT_TYPE(Class, Base) \
7465 case Type::Class: \
7466 llvm_unreachable( \
7467 "dependent types aren't supported in the constant evaluator!");
7468 #define NON_CANONICAL_UNLESS_DEPENDENT(Class, Base) \
7469 case Type::Class: \
7470 llvm_unreachable("either dependent or not canonical!");
7471 #include "clang/AST/TypeNodes.inc"
7472 }
7473 llvm_unreachable("Unhandled Type::TypeClass");
7474 }
7475
7476 public:
7477 // Pull out a full value of type DstType.
convert(EvalInfo & Info,BitCastBuffer & Buffer,const CastExpr * BCE)7478 static std::optional<APValue> convert(EvalInfo &Info, BitCastBuffer &Buffer,
7479 const CastExpr *BCE) {
7480 BufferToAPValueConverter Converter(Info, Buffer, BCE);
7481 return Converter.visitType(BCE->getType(), CharUnits::fromQuantity(0));
7482 }
7483 };
7484
checkBitCastConstexprEligibilityType(SourceLocation Loc,QualType Ty,EvalInfo * Info,const ASTContext & Ctx,bool CheckingDest)7485 static bool checkBitCastConstexprEligibilityType(SourceLocation Loc,
7486 QualType Ty, EvalInfo *Info,
7487 const ASTContext &Ctx,
7488 bool CheckingDest) {
7489 Ty = Ty.getCanonicalType();
7490
7491 auto diag = [&](int Reason) {
7492 if (Info)
7493 Info->FFDiag(Loc, diag::note_constexpr_bit_cast_invalid_type)
7494 << CheckingDest << (Reason == 4) << Reason;
7495 return false;
7496 };
7497 auto note = [&](int Construct, QualType NoteTy, SourceLocation NoteLoc) {
7498 if (Info)
7499 Info->Note(NoteLoc, diag::note_constexpr_bit_cast_invalid_subtype)
7500 << NoteTy << Construct << Ty;
7501 return false;
7502 };
7503
7504 if (Ty->isUnionType())
7505 return diag(0);
7506 if (Ty->isPointerType())
7507 return diag(1);
7508 if (Ty->isMemberPointerType())
7509 return diag(2);
7510 if (Ty.isVolatileQualified())
7511 return diag(3);
7512
7513 if (RecordDecl *Record = Ty->getAsRecordDecl()) {
7514 if (auto *CXXRD = dyn_cast<CXXRecordDecl>(Record)) {
7515 for (CXXBaseSpecifier &BS : CXXRD->bases())
7516 if (!checkBitCastConstexprEligibilityType(Loc, BS.getType(), Info, Ctx,
7517 CheckingDest))
7518 return note(1, BS.getType(), BS.getBeginLoc());
7519 }
7520 for (FieldDecl *FD : Record->fields()) {
7521 if (FD->getType()->isReferenceType())
7522 return diag(4);
7523 if (!checkBitCastConstexprEligibilityType(Loc, FD->getType(), Info, Ctx,
7524 CheckingDest))
7525 return note(0, FD->getType(), FD->getBeginLoc());
7526 }
7527 }
7528
7529 if (Ty->isArrayType() &&
7530 !checkBitCastConstexprEligibilityType(Loc, Ctx.getBaseElementType(Ty),
7531 Info, Ctx, CheckingDest))
7532 return false;
7533
7534 return true;
7535 }
7536
checkBitCastConstexprEligibility(EvalInfo * Info,const ASTContext & Ctx,const CastExpr * BCE)7537 static bool checkBitCastConstexprEligibility(EvalInfo *Info,
7538 const ASTContext &Ctx,
7539 const CastExpr *BCE) {
7540 bool DestOK = checkBitCastConstexprEligibilityType(
7541 BCE->getBeginLoc(), BCE->getType(), Info, Ctx, true);
7542 bool SourceOK = DestOK && checkBitCastConstexprEligibilityType(
7543 BCE->getBeginLoc(),
7544 BCE->getSubExpr()->getType(), Info, Ctx, false);
7545 return SourceOK;
7546 }
7547
handleRValueToRValueBitCast(EvalInfo & Info,APValue & DestValue,const APValue & SourceRValue,const CastExpr * BCE)7548 static bool handleRValueToRValueBitCast(EvalInfo &Info, APValue &DestValue,
7549 const APValue &SourceRValue,
7550 const CastExpr *BCE) {
7551 assert(CHAR_BIT == 8 && Info.Ctx.getTargetInfo().getCharWidth() == 8 &&
7552 "no host or target supports non 8-bit chars");
7553
7554 if (!checkBitCastConstexprEligibility(&Info, Info.Ctx, BCE))
7555 return false;
7556
7557 // Read out SourceValue into a char buffer.
7558 std::optional<BitCastBuffer> Buffer =
7559 APValueToBufferConverter::convert(Info, SourceRValue, BCE);
7560 if (!Buffer)
7561 return false;
7562
7563 // Write out the buffer into a new APValue.
7564 std::optional<APValue> MaybeDestValue =
7565 BufferToAPValueConverter::convert(Info, *Buffer, BCE);
7566 if (!MaybeDestValue)
7567 return false;
7568
7569 DestValue = std::move(*MaybeDestValue);
7570 return true;
7571 }
7572
handleLValueToRValueBitCast(EvalInfo & Info,APValue & DestValue,APValue & SourceValue,const CastExpr * BCE)7573 static bool handleLValueToRValueBitCast(EvalInfo &Info, APValue &DestValue,
7574 APValue &SourceValue,
7575 const CastExpr *BCE) {
7576 assert(CHAR_BIT == 8 && Info.Ctx.getTargetInfo().getCharWidth() == 8 &&
7577 "no host or target supports non 8-bit chars");
7578 assert(SourceValue.isLValue() &&
7579 "LValueToRValueBitcast requires an lvalue operand!");
7580
7581 LValue SourceLValue;
7582 APValue SourceRValue;
7583 SourceLValue.setFrom(Info.Ctx, SourceValue);
7584 if (!handleLValueToRValueConversion(
7585 Info, BCE, BCE->getSubExpr()->getType().withConst(), SourceLValue,
7586 SourceRValue, /*WantObjectRepresentation=*/true))
7587 return false;
7588
7589 return handleRValueToRValueBitCast(Info, DestValue, SourceRValue, BCE);
7590 }
7591
7592 template <class Derived>
7593 class ExprEvaluatorBase
7594 : public ConstStmtVisitor<Derived, bool> {
7595 private:
getDerived()7596 Derived &getDerived() { return static_cast<Derived&>(*this); }
DerivedSuccess(const APValue & V,const Expr * E)7597 bool DerivedSuccess(const APValue &V, const Expr *E) {
7598 return getDerived().Success(V, E);
7599 }
DerivedZeroInitialization(const Expr * E)7600 bool DerivedZeroInitialization(const Expr *E) {
7601 return getDerived().ZeroInitialization(E);
7602 }
7603
7604 // Check whether a conditional operator with a non-constant condition is a
7605 // potential constant expression. If neither arm is a potential constant
7606 // expression, then the conditional operator is not either.
7607 template<typename ConditionalOperator>
CheckPotentialConstantConditional(const ConditionalOperator * E)7608 void CheckPotentialConstantConditional(const ConditionalOperator *E) {
7609 assert(Info.checkingPotentialConstantExpression());
7610
7611 // Speculatively evaluate both arms.
7612 SmallVector<PartialDiagnosticAt, 8> Diag;
7613 {
7614 SpeculativeEvaluationRAII Speculate(Info, &Diag);
7615 StmtVisitorTy::Visit(E->getFalseExpr());
7616 if (Diag.empty())
7617 return;
7618 }
7619
7620 {
7621 SpeculativeEvaluationRAII Speculate(Info, &Diag);
7622 Diag.clear();
7623 StmtVisitorTy::Visit(E->getTrueExpr());
7624 if (Diag.empty())
7625 return;
7626 }
7627
7628 Error(E, diag::note_constexpr_conditional_never_const);
7629 }
7630
7631
7632 template<typename ConditionalOperator>
HandleConditionalOperator(const ConditionalOperator * E)7633 bool HandleConditionalOperator(const ConditionalOperator *E) {
7634 bool BoolResult;
7635 if (!EvaluateAsBooleanCondition(E->getCond(), BoolResult, Info)) {
7636 if (Info.checkingPotentialConstantExpression() && Info.noteFailure()) {
7637 CheckPotentialConstantConditional(E);
7638 return false;
7639 }
7640 if (Info.noteFailure()) {
7641 StmtVisitorTy::Visit(E->getTrueExpr());
7642 StmtVisitorTy::Visit(E->getFalseExpr());
7643 }
7644 return false;
7645 }
7646
7647 Expr *EvalExpr = BoolResult ? E->getTrueExpr() : E->getFalseExpr();
7648 return StmtVisitorTy::Visit(EvalExpr);
7649 }
7650
7651 protected:
7652 EvalInfo &Info;
7653 typedef ConstStmtVisitor<Derived, bool> StmtVisitorTy;
7654 typedef ExprEvaluatorBase ExprEvaluatorBaseTy;
7655
CCEDiag(const Expr * E,diag::kind D)7656 OptionalDiagnostic CCEDiag(const Expr *E, diag::kind D) {
7657 return Info.CCEDiag(E, D);
7658 }
7659
ZeroInitialization(const Expr * E)7660 bool ZeroInitialization(const Expr *E) { return Error(E); }
7661
IsConstantEvaluatedBuiltinCall(const CallExpr * E)7662 bool IsConstantEvaluatedBuiltinCall(const CallExpr *E) {
7663 unsigned BuiltinOp = E->getBuiltinCallee();
7664 return BuiltinOp != 0 &&
7665 Info.Ctx.BuiltinInfo.isConstantEvaluated(BuiltinOp);
7666 }
7667
7668 public:
ExprEvaluatorBase(EvalInfo & Info)7669 ExprEvaluatorBase(EvalInfo &Info) : Info(Info) {}
7670
getEvalInfo()7671 EvalInfo &getEvalInfo() { return Info; }
7672
7673 /// Report an evaluation error. This should only be called when an error is
7674 /// first discovered. When propagating an error, just return false.
Error(const Expr * E,diag::kind D)7675 bool Error(const Expr *E, diag::kind D) {
7676 Info.FFDiag(E, D) << E->getSourceRange();
7677 return false;
7678 }
Error(const Expr * E)7679 bool Error(const Expr *E) {
7680 return Error(E, diag::note_invalid_subexpr_in_const_expr);
7681 }
7682
VisitStmt(const Stmt *)7683 bool VisitStmt(const Stmt *) {
7684 llvm_unreachable("Expression evaluator should not be called on stmts");
7685 }
VisitExpr(const Expr * E)7686 bool VisitExpr(const Expr *E) {
7687 return Error(E);
7688 }
7689
VisitPredefinedExpr(const PredefinedExpr * E)7690 bool VisitPredefinedExpr(const PredefinedExpr *E) {
7691 return StmtVisitorTy::Visit(E->getFunctionName());
7692 }
VisitConstantExpr(const ConstantExpr * E)7693 bool VisitConstantExpr(const ConstantExpr *E) {
7694 if (E->hasAPValueResult())
7695 return DerivedSuccess(E->getAPValueResult(), E);
7696
7697 return StmtVisitorTy::Visit(E->getSubExpr());
7698 }
7699
VisitParenExpr(const ParenExpr * E)7700 bool VisitParenExpr(const ParenExpr *E)
7701 { return StmtVisitorTy::Visit(E->getSubExpr()); }
VisitUnaryExtension(const UnaryOperator * E)7702 bool VisitUnaryExtension(const UnaryOperator *E)
7703 { return StmtVisitorTy::Visit(E->getSubExpr()); }
VisitUnaryPlus(const UnaryOperator * E)7704 bool VisitUnaryPlus(const UnaryOperator *E)
7705 { return StmtVisitorTy::Visit(E->getSubExpr()); }
VisitChooseExpr(const ChooseExpr * E)7706 bool VisitChooseExpr(const ChooseExpr *E)
7707 { return StmtVisitorTy::Visit(E->getChosenSubExpr()); }
VisitGenericSelectionExpr(const GenericSelectionExpr * E)7708 bool VisitGenericSelectionExpr(const GenericSelectionExpr *E)
7709 { return StmtVisitorTy::Visit(E->getResultExpr()); }
VisitSubstNonTypeTemplateParmExpr(const SubstNonTypeTemplateParmExpr * E)7710 bool VisitSubstNonTypeTemplateParmExpr(const SubstNonTypeTemplateParmExpr *E)
7711 { return StmtVisitorTy::Visit(E->getReplacement()); }
VisitCXXDefaultArgExpr(const CXXDefaultArgExpr * E)7712 bool VisitCXXDefaultArgExpr(const CXXDefaultArgExpr *E) {
7713 TempVersionRAII RAII(*Info.CurrentCall);
7714 SourceLocExprScopeGuard Guard(E, Info.CurrentCall->CurSourceLocExprScope);
7715 return StmtVisitorTy::Visit(E->getExpr());
7716 }
VisitCXXDefaultInitExpr(const CXXDefaultInitExpr * E)7717 bool VisitCXXDefaultInitExpr(const CXXDefaultInitExpr *E) {
7718 TempVersionRAII RAII(*Info.CurrentCall);
7719 // The initializer may not have been parsed yet, or might be erroneous.
7720 if (!E->getExpr())
7721 return Error(E);
7722 SourceLocExprScopeGuard Guard(E, Info.CurrentCall->CurSourceLocExprScope);
7723 return StmtVisitorTy::Visit(E->getExpr());
7724 }
7725
VisitExprWithCleanups(const ExprWithCleanups * E)7726 bool VisitExprWithCleanups(const ExprWithCleanups *E) {
7727 FullExpressionRAII Scope(Info);
7728 return StmtVisitorTy::Visit(E->getSubExpr()) && Scope.destroy();
7729 }
7730
7731 // Temporaries are registered when created, so we don't care about
7732 // CXXBindTemporaryExpr.
VisitCXXBindTemporaryExpr(const CXXBindTemporaryExpr * E)7733 bool VisitCXXBindTemporaryExpr(const CXXBindTemporaryExpr *E) {
7734 return StmtVisitorTy::Visit(E->getSubExpr());
7735 }
7736
VisitCXXReinterpretCastExpr(const CXXReinterpretCastExpr * E)7737 bool VisitCXXReinterpretCastExpr(const CXXReinterpretCastExpr *E) {
7738 CCEDiag(E, diag::note_constexpr_invalid_cast) << 0;
7739 return static_cast<Derived*>(this)->VisitCastExpr(E);
7740 }
VisitCXXDynamicCastExpr(const CXXDynamicCastExpr * E)7741 bool VisitCXXDynamicCastExpr(const CXXDynamicCastExpr *E) {
7742 if (!Info.Ctx.getLangOpts().CPlusPlus20)
7743 CCEDiag(E, diag::note_constexpr_invalid_cast) << 1;
7744 return static_cast<Derived*>(this)->VisitCastExpr(E);
7745 }
VisitBuiltinBitCastExpr(const BuiltinBitCastExpr * E)7746 bool VisitBuiltinBitCastExpr(const BuiltinBitCastExpr *E) {
7747 return static_cast<Derived*>(this)->VisitCastExpr(E);
7748 }
7749
VisitBinaryOperator(const BinaryOperator * E)7750 bool VisitBinaryOperator(const BinaryOperator *E) {
7751 switch (E->getOpcode()) {
7752 default:
7753 return Error(E);
7754
7755 case BO_Comma:
7756 VisitIgnoredValue(E->getLHS());
7757 return StmtVisitorTy::Visit(E->getRHS());
7758
7759 case BO_PtrMemD:
7760 case BO_PtrMemI: {
7761 LValue Obj;
7762 if (!HandleMemberPointerAccess(Info, E, Obj))
7763 return false;
7764 APValue Result;
7765 if (!handleLValueToRValueConversion(Info, E, E->getType(), Obj, Result))
7766 return false;
7767 return DerivedSuccess(Result, E);
7768 }
7769 }
7770 }
7771
VisitCXXRewrittenBinaryOperator(const CXXRewrittenBinaryOperator * E)7772 bool VisitCXXRewrittenBinaryOperator(const CXXRewrittenBinaryOperator *E) {
7773 return StmtVisitorTy::Visit(E->getSemanticForm());
7774 }
7775
VisitBinaryConditionalOperator(const BinaryConditionalOperator * E)7776 bool VisitBinaryConditionalOperator(const BinaryConditionalOperator *E) {
7777 // Evaluate and cache the common expression. We treat it as a temporary,
7778 // even though it's not quite the same thing.
7779 LValue CommonLV;
7780 if (!Evaluate(Info.CurrentCall->createTemporary(
7781 E->getOpaqueValue(),
7782 getStorageType(Info.Ctx, E->getOpaqueValue()),
7783 ScopeKind::FullExpression, CommonLV),
7784 Info, E->getCommon()))
7785 return false;
7786
7787 return HandleConditionalOperator(E);
7788 }
7789
VisitConditionalOperator(const ConditionalOperator * E)7790 bool VisitConditionalOperator(const ConditionalOperator *E) {
7791 bool IsBcpCall = false;
7792 // If the condition (ignoring parens) is a __builtin_constant_p call,
7793 // the result is a constant expression if it can be folded without
7794 // side-effects. This is an important GNU extension. See GCC PR38377
7795 // for discussion.
7796 if (const CallExpr *CallCE =
7797 dyn_cast<CallExpr>(E->getCond()->IgnoreParenCasts()))
7798 if (CallCE->getBuiltinCallee() == Builtin::BI__builtin_constant_p)
7799 IsBcpCall = true;
7800
7801 // Always assume __builtin_constant_p(...) ? ... : ... is a potential
7802 // constant expression; we can't check whether it's potentially foldable.
7803 // FIXME: We should instead treat __builtin_constant_p as non-constant if
7804 // it would return 'false' in this mode.
7805 if (Info.checkingPotentialConstantExpression() && IsBcpCall)
7806 return false;
7807
7808 FoldConstant Fold(Info, IsBcpCall);
7809 if (!HandleConditionalOperator(E)) {
7810 Fold.keepDiagnostics();
7811 return false;
7812 }
7813
7814 return true;
7815 }
7816
VisitOpaqueValueExpr(const OpaqueValueExpr * E)7817 bool VisitOpaqueValueExpr(const OpaqueValueExpr *E) {
7818 if (APValue *Value = Info.CurrentCall->getCurrentTemporary(E);
7819 Value && !Value->isAbsent())
7820 return DerivedSuccess(*Value, E);
7821
7822 const Expr *Source = E->getSourceExpr();
7823 if (!Source)
7824 return Error(E);
7825 if (Source == E) {
7826 assert(0 && "OpaqueValueExpr recursively refers to itself");
7827 return Error(E);
7828 }
7829 return StmtVisitorTy::Visit(Source);
7830 }
7831
VisitPseudoObjectExpr(const PseudoObjectExpr * E)7832 bool VisitPseudoObjectExpr(const PseudoObjectExpr *E) {
7833 for (const Expr *SemE : E->semantics()) {
7834 if (auto *OVE = dyn_cast<OpaqueValueExpr>(SemE)) {
7835 // FIXME: We can't handle the case where an OpaqueValueExpr is also the
7836 // result expression: there could be two different LValues that would
7837 // refer to the same object in that case, and we can't model that.
7838 if (SemE == E->getResultExpr())
7839 return Error(E);
7840
7841 // Unique OVEs get evaluated if and when we encounter them when
7842 // emitting the rest of the semantic form, rather than eagerly.
7843 if (OVE->isUnique())
7844 continue;
7845
7846 LValue LV;
7847 if (!Evaluate(Info.CurrentCall->createTemporary(
7848 OVE, getStorageType(Info.Ctx, OVE),
7849 ScopeKind::FullExpression, LV),
7850 Info, OVE->getSourceExpr()))
7851 return false;
7852 } else if (SemE == E->getResultExpr()) {
7853 if (!StmtVisitorTy::Visit(SemE))
7854 return false;
7855 } else {
7856 if (!EvaluateIgnoredValue(Info, SemE))
7857 return false;
7858 }
7859 }
7860 return true;
7861 }
7862
VisitCallExpr(const CallExpr * E)7863 bool VisitCallExpr(const CallExpr *E) {
7864 APValue Result;
7865 if (!handleCallExpr(E, Result, nullptr))
7866 return false;
7867 return DerivedSuccess(Result, E);
7868 }
7869
handleCallExpr(const CallExpr * E,APValue & Result,const LValue * ResultSlot)7870 bool handleCallExpr(const CallExpr *E, APValue &Result,
7871 const LValue *ResultSlot) {
7872 CallScopeRAII CallScope(Info);
7873
7874 const Expr *Callee = E->getCallee()->IgnoreParens();
7875 QualType CalleeType = Callee->getType();
7876
7877 const FunctionDecl *FD = nullptr;
7878 LValue *This = nullptr, ThisVal;
7879 auto Args = llvm::ArrayRef(E->getArgs(), E->getNumArgs());
7880 bool HasQualifier = false;
7881
7882 CallRef Call;
7883
7884 // Extract function decl and 'this' pointer from the callee.
7885 if (CalleeType->isSpecificBuiltinType(BuiltinType::BoundMember)) {
7886 const CXXMethodDecl *Member = nullptr;
7887 if (const MemberExpr *ME = dyn_cast<MemberExpr>(Callee)) {
7888 // Explicit bound member calls, such as x.f() or p->g();
7889 if (!EvaluateObjectArgument(Info, ME->getBase(), ThisVal))
7890 return false;
7891 Member = dyn_cast<CXXMethodDecl>(ME->getMemberDecl());
7892 if (!Member)
7893 return Error(Callee);
7894 This = &ThisVal;
7895 HasQualifier = ME->hasQualifier();
7896 } else if (const BinaryOperator *BE = dyn_cast<BinaryOperator>(Callee)) {
7897 // Indirect bound member calls ('.*' or '->*').
7898 const ValueDecl *D =
7899 HandleMemberPointerAccess(Info, BE, ThisVal, false);
7900 if (!D)
7901 return false;
7902 Member = dyn_cast<CXXMethodDecl>(D);
7903 if (!Member)
7904 return Error(Callee);
7905 This = &ThisVal;
7906 } else if (const auto *PDE = dyn_cast<CXXPseudoDestructorExpr>(Callee)) {
7907 if (!Info.getLangOpts().CPlusPlus20)
7908 Info.CCEDiag(PDE, diag::note_constexpr_pseudo_destructor);
7909 return EvaluateObjectArgument(Info, PDE->getBase(), ThisVal) &&
7910 HandleDestruction(Info, PDE, ThisVal, PDE->getDestroyedType());
7911 } else
7912 return Error(Callee);
7913 FD = Member;
7914 } else if (CalleeType->isFunctionPointerType()) {
7915 LValue CalleeLV;
7916 if (!EvaluatePointer(Callee, CalleeLV, Info))
7917 return false;
7918
7919 if (!CalleeLV.getLValueOffset().isZero())
7920 return Error(Callee);
7921 if (CalleeLV.isNullPointer()) {
7922 Info.FFDiag(Callee, diag::note_constexpr_null_callee)
7923 << const_cast<Expr *>(Callee);
7924 return false;
7925 }
7926 FD = dyn_cast_or_null<FunctionDecl>(
7927 CalleeLV.getLValueBase().dyn_cast<const ValueDecl *>());
7928 if (!FD)
7929 return Error(Callee);
7930 // Don't call function pointers which have been cast to some other type.
7931 // Per DR (no number yet), the caller and callee can differ in noexcept.
7932 if (!Info.Ctx.hasSameFunctionTypeIgnoringExceptionSpec(
7933 CalleeType->getPointeeType(), FD->getType())) {
7934 return Error(E);
7935 }
7936
7937 // For an (overloaded) assignment expression, evaluate the RHS before the
7938 // LHS.
7939 auto *OCE = dyn_cast<CXXOperatorCallExpr>(E);
7940 if (OCE && OCE->isAssignmentOp()) {
7941 assert(Args.size() == 2 && "wrong number of arguments in assignment");
7942 Call = Info.CurrentCall->createCall(FD);
7943 bool HasThis = false;
7944 if (const auto *MD = dyn_cast<CXXMethodDecl>(FD))
7945 HasThis = MD->isImplicitObjectMemberFunction();
7946 if (!EvaluateArgs(HasThis ? Args.slice(1) : Args, Call, Info, FD,
7947 /*RightToLeft=*/true))
7948 return false;
7949 }
7950
7951 // Overloaded operator calls to member functions are represented as normal
7952 // calls with '*this' as the first argument.
7953 const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD);
7954 if (MD &&
7955 (MD->isImplicitObjectMemberFunction() || (OCE && MD->isStatic()))) {
7956 // FIXME: When selecting an implicit conversion for an overloaded
7957 // operator delete, we sometimes try to evaluate calls to conversion
7958 // operators without a 'this' parameter!
7959 if (Args.empty())
7960 return Error(E);
7961
7962 if (!EvaluateObjectArgument(Info, Args[0], ThisVal))
7963 return false;
7964
7965 // If we are calling a static operator, the 'this' argument needs to be
7966 // ignored after being evaluated.
7967 if (MD->isInstance())
7968 This = &ThisVal;
7969
7970 // If this is syntactically a simple assignment using a trivial
7971 // assignment operator, start the lifetimes of union members as needed,
7972 // per C++20 [class.union]5.
7973 if (Info.getLangOpts().CPlusPlus20 && OCE &&
7974 OCE->getOperator() == OO_Equal && MD->isTrivial() &&
7975 !MaybeHandleUnionActiveMemberChange(Info, Args[0], ThisVal))
7976 return false;
7977
7978 Args = Args.slice(1);
7979 } else if (MD && MD->isLambdaStaticInvoker()) {
7980 // Map the static invoker for the lambda back to the call operator.
7981 // Conveniently, we don't have to slice out the 'this' argument (as is
7982 // being done for the non-static case), since a static member function
7983 // doesn't have an implicit argument passed in.
7984 const CXXRecordDecl *ClosureClass = MD->getParent();
7985 assert(
7986 ClosureClass->captures_begin() == ClosureClass->captures_end() &&
7987 "Number of captures must be zero for conversion to function-ptr");
7988
7989 const CXXMethodDecl *LambdaCallOp =
7990 ClosureClass->getLambdaCallOperator();
7991
7992 // Set 'FD', the function that will be called below, to the call
7993 // operator. If the closure object represents a generic lambda, find
7994 // the corresponding specialization of the call operator.
7995
7996 if (ClosureClass->isGenericLambda()) {
7997 assert(MD->isFunctionTemplateSpecialization() &&
7998 "A generic lambda's static-invoker function must be a "
7999 "template specialization");
8000 const TemplateArgumentList *TAL = MD->getTemplateSpecializationArgs();
8001 FunctionTemplateDecl *CallOpTemplate =
8002 LambdaCallOp->getDescribedFunctionTemplate();
8003 void *InsertPos = nullptr;
8004 FunctionDecl *CorrespondingCallOpSpecialization =
8005 CallOpTemplate->findSpecialization(TAL->asArray(), InsertPos);
8006 assert(CorrespondingCallOpSpecialization &&
8007 "We must always have a function call operator specialization "
8008 "that corresponds to our static invoker specialization");
8009 FD = cast<CXXMethodDecl>(CorrespondingCallOpSpecialization);
8010 } else
8011 FD = LambdaCallOp;
8012 } else if (FD->isReplaceableGlobalAllocationFunction()) {
8013 if (FD->getDeclName().getCXXOverloadedOperator() == OO_New ||
8014 FD->getDeclName().getCXXOverloadedOperator() == OO_Array_New) {
8015 LValue Ptr;
8016 if (!HandleOperatorNewCall(Info, E, Ptr))
8017 return false;
8018 Ptr.moveInto(Result);
8019 return CallScope.destroy();
8020 } else {
8021 return HandleOperatorDeleteCall(Info, E) && CallScope.destroy();
8022 }
8023 }
8024 } else
8025 return Error(E);
8026
8027 // Evaluate the arguments now if we've not already done so.
8028 if (!Call) {
8029 Call = Info.CurrentCall->createCall(FD);
8030 if (!EvaluateArgs(Args, Call, Info, FD))
8031 return false;
8032 }
8033
8034 SmallVector<QualType, 4> CovariantAdjustmentPath;
8035 if (This) {
8036 auto *NamedMember = dyn_cast<CXXMethodDecl>(FD);
8037 if (NamedMember && NamedMember->isVirtual() && !HasQualifier) {
8038 // Perform virtual dispatch, if necessary.
8039 FD = HandleVirtualDispatch(Info, E, *This, NamedMember,
8040 CovariantAdjustmentPath);
8041 if (!FD)
8042 return false;
8043 } else if (NamedMember && NamedMember->isImplicitObjectMemberFunction()) {
8044 // Check that the 'this' pointer points to an object of the right type.
8045 // FIXME: If this is an assignment operator call, we may need to change
8046 // the active union member before we check this.
8047 if (!checkNonVirtualMemberCallThisPointer(Info, E, *This, NamedMember))
8048 return false;
8049 }
8050 }
8051
8052 // Destructor calls are different enough that they have their own codepath.
8053 if (auto *DD = dyn_cast<CXXDestructorDecl>(FD)) {
8054 assert(This && "no 'this' pointer for destructor call");
8055 return HandleDestruction(Info, E, *This,
8056 Info.Ctx.getRecordType(DD->getParent())) &&
8057 CallScope.destroy();
8058 }
8059
8060 const FunctionDecl *Definition = nullptr;
8061 Stmt *Body = FD->getBody(Definition);
8062
8063 if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition, Body) ||
8064 !HandleFunctionCall(E->getExprLoc(), Definition, This, E, Args, Call,
8065 Body, Info, Result, ResultSlot))
8066 return false;
8067
8068 if (!CovariantAdjustmentPath.empty() &&
8069 !HandleCovariantReturnAdjustment(Info, E, Result,
8070 CovariantAdjustmentPath))
8071 return false;
8072
8073 return CallScope.destroy();
8074 }
8075
VisitCompoundLiteralExpr(const CompoundLiteralExpr * E)8076 bool VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) {
8077 return StmtVisitorTy::Visit(E->getInitializer());
8078 }
VisitInitListExpr(const InitListExpr * E)8079 bool VisitInitListExpr(const InitListExpr *E) {
8080 if (E->getNumInits() == 0)
8081 return DerivedZeroInitialization(E);
8082 if (E->getNumInits() == 1)
8083 return StmtVisitorTy::Visit(E->getInit(0));
8084 return Error(E);
8085 }
VisitImplicitValueInitExpr(const ImplicitValueInitExpr * E)8086 bool VisitImplicitValueInitExpr(const ImplicitValueInitExpr *E) {
8087 return DerivedZeroInitialization(E);
8088 }
VisitCXXScalarValueInitExpr(const CXXScalarValueInitExpr * E)8089 bool VisitCXXScalarValueInitExpr(const CXXScalarValueInitExpr *E) {
8090 return DerivedZeroInitialization(E);
8091 }
VisitCXXNullPtrLiteralExpr(const CXXNullPtrLiteralExpr * E)8092 bool VisitCXXNullPtrLiteralExpr(const CXXNullPtrLiteralExpr *E) {
8093 return DerivedZeroInitialization(E);
8094 }
8095
8096 /// A member expression where the object is a prvalue is itself a prvalue.
VisitMemberExpr(const MemberExpr * E)8097 bool VisitMemberExpr(const MemberExpr *E) {
8098 assert(!Info.Ctx.getLangOpts().CPlusPlus11 &&
8099 "missing temporary materialization conversion");
8100 assert(!E->isArrow() && "missing call to bound member function?");
8101
8102 APValue Val;
8103 if (!Evaluate(Val, Info, E->getBase()))
8104 return false;
8105
8106 QualType BaseTy = E->getBase()->getType();
8107
8108 const FieldDecl *FD = dyn_cast<FieldDecl>(E->getMemberDecl());
8109 if (!FD) return Error(E);
8110 assert(!FD->getType()->isReferenceType() && "prvalue reference?");
8111 assert(BaseTy->castAs<RecordType>()->getDecl()->getCanonicalDecl() ==
8112 FD->getParent()->getCanonicalDecl() && "record / field mismatch");
8113
8114 // Note: there is no lvalue base here. But this case should only ever
8115 // happen in C or in C++98, where we cannot be evaluating a constexpr
8116 // constructor, which is the only case the base matters.
8117 CompleteObject Obj(APValue::LValueBase(), &Val, BaseTy);
8118 SubobjectDesignator Designator(BaseTy);
8119 Designator.addDeclUnchecked(FD);
8120
8121 APValue Result;
8122 return extractSubobject(Info, E, Obj, Designator, Result) &&
8123 DerivedSuccess(Result, E);
8124 }
8125
VisitExtVectorElementExpr(const ExtVectorElementExpr * E)8126 bool VisitExtVectorElementExpr(const ExtVectorElementExpr *E) {
8127 APValue Val;
8128 if (!Evaluate(Val, Info, E->getBase()))
8129 return false;
8130
8131 if (Val.isVector()) {
8132 SmallVector<uint32_t, 4> Indices;
8133 E->getEncodedElementAccess(Indices);
8134 if (Indices.size() == 1) {
8135 // Return scalar.
8136 return DerivedSuccess(Val.getVectorElt(Indices[0]), E);
8137 } else {
8138 // Construct new APValue vector.
8139 SmallVector<APValue, 4> Elts;
8140 for (unsigned I = 0; I < Indices.size(); ++I) {
8141 Elts.push_back(Val.getVectorElt(Indices[I]));
8142 }
8143 APValue VecResult(Elts.data(), Indices.size());
8144 return DerivedSuccess(VecResult, E);
8145 }
8146 }
8147
8148 return false;
8149 }
8150
VisitCastExpr(const CastExpr * E)8151 bool VisitCastExpr(const CastExpr *E) {
8152 switch (E->getCastKind()) {
8153 default:
8154 break;
8155
8156 case CK_AtomicToNonAtomic: {
8157 APValue AtomicVal;
8158 // This does not need to be done in place even for class/array types:
8159 // atomic-to-non-atomic conversion implies copying the object
8160 // representation.
8161 if (!Evaluate(AtomicVal, Info, E->getSubExpr()))
8162 return false;
8163 return DerivedSuccess(AtomicVal, E);
8164 }
8165
8166 case CK_NoOp:
8167 case CK_UserDefinedConversion:
8168 return StmtVisitorTy::Visit(E->getSubExpr());
8169
8170 case CK_LValueToRValue: {
8171 LValue LVal;
8172 if (!EvaluateLValue(E->getSubExpr(), LVal, Info))
8173 return false;
8174 APValue RVal;
8175 // Note, we use the subexpression's type in order to retain cv-qualifiers.
8176 if (!handleLValueToRValueConversion(Info, E, E->getSubExpr()->getType(),
8177 LVal, RVal))
8178 return false;
8179 return DerivedSuccess(RVal, E);
8180 }
8181 case CK_LValueToRValueBitCast: {
8182 APValue DestValue, SourceValue;
8183 if (!Evaluate(SourceValue, Info, E->getSubExpr()))
8184 return false;
8185 if (!handleLValueToRValueBitCast(Info, DestValue, SourceValue, E))
8186 return false;
8187 return DerivedSuccess(DestValue, E);
8188 }
8189
8190 case CK_AddressSpaceConversion: {
8191 APValue Value;
8192 if (!Evaluate(Value, Info, E->getSubExpr()))
8193 return false;
8194 return DerivedSuccess(Value, E);
8195 }
8196 }
8197
8198 return Error(E);
8199 }
8200
VisitUnaryPostInc(const UnaryOperator * UO)8201 bool VisitUnaryPostInc(const UnaryOperator *UO) {
8202 return VisitUnaryPostIncDec(UO);
8203 }
VisitUnaryPostDec(const UnaryOperator * UO)8204 bool VisitUnaryPostDec(const UnaryOperator *UO) {
8205 return VisitUnaryPostIncDec(UO);
8206 }
VisitUnaryPostIncDec(const UnaryOperator * UO)8207 bool VisitUnaryPostIncDec(const UnaryOperator *UO) {
8208 if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure())
8209 return Error(UO);
8210
8211 LValue LVal;
8212 if (!EvaluateLValue(UO->getSubExpr(), LVal, Info))
8213 return false;
8214 APValue RVal;
8215 if (!handleIncDec(this->Info, UO, LVal, UO->getSubExpr()->getType(),
8216 UO->isIncrementOp(), &RVal))
8217 return false;
8218 return DerivedSuccess(RVal, UO);
8219 }
8220
VisitStmtExpr(const StmtExpr * E)8221 bool VisitStmtExpr(const StmtExpr *E) {
8222 // We will have checked the full-expressions inside the statement expression
8223 // when they were completed, and don't need to check them again now.
8224 llvm::SaveAndRestore NotCheckingForUB(Info.CheckingForUndefinedBehavior,
8225 false);
8226
8227 const CompoundStmt *CS = E->getSubStmt();
8228 if (CS->body_empty())
8229 return true;
8230
8231 BlockScopeRAII Scope(Info);
8232 for (CompoundStmt::const_body_iterator BI = CS->body_begin(),
8233 BE = CS->body_end();
8234 /**/; ++BI) {
8235 if (BI + 1 == BE) {
8236 const Expr *FinalExpr = dyn_cast<Expr>(*BI);
8237 if (!FinalExpr) {
8238 Info.FFDiag((*BI)->getBeginLoc(),
8239 diag::note_constexpr_stmt_expr_unsupported);
8240 return false;
8241 }
8242 return this->Visit(FinalExpr) && Scope.destroy();
8243 }
8244
8245 APValue ReturnValue;
8246 StmtResult Result = { ReturnValue, nullptr };
8247 EvalStmtResult ESR = EvaluateStmt(Result, Info, *BI);
8248 if (ESR != ESR_Succeeded) {
8249 // FIXME: If the statement-expression terminated due to 'return',
8250 // 'break', or 'continue', it would be nice to propagate that to
8251 // the outer statement evaluation rather than bailing out.
8252 if (ESR != ESR_Failed)
8253 Info.FFDiag((*BI)->getBeginLoc(),
8254 diag::note_constexpr_stmt_expr_unsupported);
8255 return false;
8256 }
8257 }
8258
8259 llvm_unreachable("Return from function from the loop above.");
8260 }
8261
8262 /// Visit a value which is evaluated, but whose value is ignored.
VisitIgnoredValue(const Expr * E)8263 void VisitIgnoredValue(const Expr *E) {
8264 EvaluateIgnoredValue(Info, E);
8265 }
8266
8267 /// Potentially visit a MemberExpr's base expression.
VisitIgnoredBaseExpression(const Expr * E)8268 void VisitIgnoredBaseExpression(const Expr *E) {
8269 // While MSVC doesn't evaluate the base expression, it does diagnose the
8270 // presence of side-effecting behavior.
8271 if (Info.getLangOpts().MSVCCompat && !E->HasSideEffects(Info.Ctx))
8272 return;
8273 VisitIgnoredValue(E);
8274 }
8275 };
8276
8277 } // namespace
8278
8279 //===----------------------------------------------------------------------===//
8280 // Common base class for lvalue and temporary evaluation.
8281 //===----------------------------------------------------------------------===//
8282 namespace {
8283 template<class Derived>
8284 class LValueExprEvaluatorBase
8285 : public ExprEvaluatorBase<Derived> {
8286 protected:
8287 LValue &Result;
8288 bool InvalidBaseOK;
8289 typedef LValueExprEvaluatorBase LValueExprEvaluatorBaseTy;
8290 typedef ExprEvaluatorBase<Derived> ExprEvaluatorBaseTy;
8291
Success(APValue::LValueBase B)8292 bool Success(APValue::LValueBase B) {
8293 Result.set(B);
8294 return true;
8295 }
8296
evaluatePointer(const Expr * E,LValue & Result)8297 bool evaluatePointer(const Expr *E, LValue &Result) {
8298 return EvaluatePointer(E, Result, this->Info, InvalidBaseOK);
8299 }
8300
8301 public:
LValueExprEvaluatorBase(EvalInfo & Info,LValue & Result,bool InvalidBaseOK)8302 LValueExprEvaluatorBase(EvalInfo &Info, LValue &Result, bool InvalidBaseOK)
8303 : ExprEvaluatorBaseTy(Info), Result(Result),
8304 InvalidBaseOK(InvalidBaseOK) {}
8305
Success(const APValue & V,const Expr * E)8306 bool Success(const APValue &V, const Expr *E) {
8307 Result.setFrom(this->Info.Ctx, V);
8308 return true;
8309 }
8310
VisitMemberExpr(const MemberExpr * E)8311 bool VisitMemberExpr(const MemberExpr *E) {
8312 // Handle non-static data members.
8313 QualType BaseTy;
8314 bool EvalOK;
8315 if (E->isArrow()) {
8316 EvalOK = evaluatePointer(E->getBase(), Result);
8317 BaseTy = E->getBase()->getType()->castAs<PointerType>()->getPointeeType();
8318 } else if (E->getBase()->isPRValue()) {
8319 assert(E->getBase()->getType()->isRecordType());
8320 EvalOK = EvaluateTemporary(E->getBase(), Result, this->Info);
8321 BaseTy = E->getBase()->getType();
8322 } else {
8323 EvalOK = this->Visit(E->getBase());
8324 BaseTy = E->getBase()->getType();
8325 }
8326 if (!EvalOK) {
8327 if (!InvalidBaseOK)
8328 return false;
8329 Result.setInvalid(E);
8330 return true;
8331 }
8332
8333 const ValueDecl *MD = E->getMemberDecl();
8334 if (const FieldDecl *FD = dyn_cast<FieldDecl>(E->getMemberDecl())) {
8335 assert(BaseTy->castAs<RecordType>()->getDecl()->getCanonicalDecl() ==
8336 FD->getParent()->getCanonicalDecl() && "record / field mismatch");
8337 (void)BaseTy;
8338 if (!HandleLValueMember(this->Info, E, Result, FD))
8339 return false;
8340 } else if (const IndirectFieldDecl *IFD = dyn_cast<IndirectFieldDecl>(MD)) {
8341 if (!HandleLValueIndirectMember(this->Info, E, Result, IFD))
8342 return false;
8343 } else
8344 return this->Error(E);
8345
8346 if (MD->getType()->isReferenceType()) {
8347 APValue RefValue;
8348 if (!handleLValueToRValueConversion(this->Info, E, MD->getType(), Result,
8349 RefValue))
8350 return false;
8351 return Success(RefValue, E);
8352 }
8353 return true;
8354 }
8355
VisitBinaryOperator(const BinaryOperator * E)8356 bool VisitBinaryOperator(const BinaryOperator *E) {
8357 switch (E->getOpcode()) {
8358 default:
8359 return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
8360
8361 case BO_PtrMemD:
8362 case BO_PtrMemI:
8363 return HandleMemberPointerAccess(this->Info, E, Result);
8364 }
8365 }
8366
VisitCastExpr(const CastExpr * E)8367 bool VisitCastExpr(const CastExpr *E) {
8368 switch (E->getCastKind()) {
8369 default:
8370 return ExprEvaluatorBaseTy::VisitCastExpr(E);
8371
8372 case CK_DerivedToBase:
8373 case CK_UncheckedDerivedToBase:
8374 if (!this->Visit(E->getSubExpr()))
8375 return false;
8376
8377 // Now figure out the necessary offset to add to the base LV to get from
8378 // the derived class to the base class.
8379 return HandleLValueBasePath(this->Info, E, E->getSubExpr()->getType(),
8380 Result);
8381 }
8382 }
8383 };
8384 }
8385
8386 //===----------------------------------------------------------------------===//
8387 // LValue Evaluation
8388 //
8389 // This is used for evaluating lvalues (in C and C++), xvalues (in C++11),
8390 // function designators (in C), decl references to void objects (in C), and
8391 // temporaries (if building with -Wno-address-of-temporary).
8392 //
8393 // LValue evaluation produces values comprising a base expression of one of the
8394 // following types:
8395 // - Declarations
8396 // * VarDecl
8397 // * FunctionDecl
8398 // - Literals
8399 // * CompoundLiteralExpr in C (and in global scope in C++)
8400 // * StringLiteral
8401 // * PredefinedExpr
8402 // * ObjCStringLiteralExpr
8403 // * ObjCEncodeExpr
8404 // * AddrLabelExpr
8405 // * BlockExpr
8406 // * CallExpr for a MakeStringConstant builtin
8407 // - typeid(T) expressions, as TypeInfoLValues
8408 // - Locals and temporaries
8409 // * MaterializeTemporaryExpr
8410 // * Any Expr, with a CallIndex indicating the function in which the temporary
8411 // was evaluated, for cases where the MaterializeTemporaryExpr is missing
8412 // from the AST (FIXME).
8413 // * A MaterializeTemporaryExpr that has static storage duration, with no
8414 // CallIndex, for a lifetime-extended temporary.
8415 // * The ConstantExpr that is currently being evaluated during evaluation of an
8416 // immediate invocation.
8417 // plus an offset in bytes.
8418 //===----------------------------------------------------------------------===//
8419 namespace {
8420 class LValueExprEvaluator
8421 : public LValueExprEvaluatorBase<LValueExprEvaluator> {
8422 public:
LValueExprEvaluator(EvalInfo & Info,LValue & Result,bool InvalidBaseOK)8423 LValueExprEvaluator(EvalInfo &Info, LValue &Result, bool InvalidBaseOK) :
8424 LValueExprEvaluatorBaseTy(Info, Result, InvalidBaseOK) {}
8425
8426 bool VisitVarDecl(const Expr *E, const VarDecl *VD);
8427 bool VisitUnaryPreIncDec(const UnaryOperator *UO);
8428
8429 bool VisitCallExpr(const CallExpr *E);
8430 bool VisitDeclRefExpr(const DeclRefExpr *E);
VisitPredefinedExpr(const PredefinedExpr * E)8431 bool VisitPredefinedExpr(const PredefinedExpr *E) { return Success(E); }
8432 bool VisitMaterializeTemporaryExpr(const MaterializeTemporaryExpr *E);
8433 bool VisitCompoundLiteralExpr(const CompoundLiteralExpr *E);
8434 bool VisitMemberExpr(const MemberExpr *E);
VisitStringLiteral(const StringLiteral * E)8435 bool VisitStringLiteral(const StringLiteral *E) { return Success(E); }
VisitObjCEncodeExpr(const ObjCEncodeExpr * E)8436 bool VisitObjCEncodeExpr(const ObjCEncodeExpr *E) { return Success(E); }
8437 bool VisitCXXTypeidExpr(const CXXTypeidExpr *E);
8438 bool VisitCXXUuidofExpr(const CXXUuidofExpr *E);
8439 bool VisitArraySubscriptExpr(const ArraySubscriptExpr *E);
8440 bool VisitUnaryDeref(const UnaryOperator *E);
8441 bool VisitUnaryReal(const UnaryOperator *E);
8442 bool VisitUnaryImag(const UnaryOperator *E);
VisitUnaryPreInc(const UnaryOperator * UO)8443 bool VisitUnaryPreInc(const UnaryOperator *UO) {
8444 return VisitUnaryPreIncDec(UO);
8445 }
VisitUnaryPreDec(const UnaryOperator * UO)8446 bool VisitUnaryPreDec(const UnaryOperator *UO) {
8447 return VisitUnaryPreIncDec(UO);
8448 }
8449 bool VisitBinAssign(const BinaryOperator *BO);
8450 bool VisitCompoundAssignOperator(const CompoundAssignOperator *CAO);
8451
VisitCastExpr(const CastExpr * E)8452 bool VisitCastExpr(const CastExpr *E) {
8453 switch (E->getCastKind()) {
8454 default:
8455 return LValueExprEvaluatorBaseTy::VisitCastExpr(E);
8456
8457 case CK_LValueBitCast:
8458 this->CCEDiag(E, diag::note_constexpr_invalid_cast)
8459 << 2 << Info.Ctx.getLangOpts().CPlusPlus;
8460 if (!Visit(E->getSubExpr()))
8461 return false;
8462 Result.Designator.setInvalid();
8463 return true;
8464
8465 case CK_BaseToDerived:
8466 if (!Visit(E->getSubExpr()))
8467 return false;
8468 return HandleBaseToDerivedCast(Info, E, Result);
8469
8470 case CK_Dynamic:
8471 if (!Visit(E->getSubExpr()))
8472 return false;
8473 return HandleDynamicCast(Info, cast<ExplicitCastExpr>(E), Result);
8474 }
8475 }
8476 };
8477 } // end anonymous namespace
8478
8479 /// Evaluate an expression as an lvalue. This can be legitimately called on
8480 /// expressions which are not glvalues, in three cases:
8481 /// * function designators in C, and
8482 /// * "extern void" objects
8483 /// * @selector() expressions in Objective-C
EvaluateLValue(const Expr * E,LValue & Result,EvalInfo & Info,bool InvalidBaseOK)8484 static bool EvaluateLValue(const Expr *E, LValue &Result, EvalInfo &Info,
8485 bool InvalidBaseOK) {
8486 assert(!E->isValueDependent());
8487 assert(E->isGLValue() || E->getType()->isFunctionType() ||
8488 E->getType()->isVoidType() || isa<ObjCSelectorExpr>(E->IgnoreParens()));
8489 return LValueExprEvaluator(Info, Result, InvalidBaseOK).Visit(E);
8490 }
8491
VisitDeclRefExpr(const DeclRefExpr * E)8492 bool LValueExprEvaluator::VisitDeclRefExpr(const DeclRefExpr *E) {
8493 const NamedDecl *D = E->getDecl();
8494 if (isa<FunctionDecl, MSGuidDecl, TemplateParamObjectDecl,
8495 UnnamedGlobalConstantDecl>(D))
8496 return Success(cast<ValueDecl>(D));
8497 if (const VarDecl *VD = dyn_cast<VarDecl>(D))
8498 return VisitVarDecl(E, VD);
8499 if (const BindingDecl *BD = dyn_cast<BindingDecl>(D))
8500 return Visit(BD->getBinding());
8501 return Error(E);
8502 }
8503
8504
VisitVarDecl(const Expr * E,const VarDecl * VD)8505 bool LValueExprEvaluator::VisitVarDecl(const Expr *E, const VarDecl *VD) {
8506
8507 // If we are within a lambda's call operator, check whether the 'VD' referred
8508 // to within 'E' actually represents a lambda-capture that maps to a
8509 // data-member/field within the closure object, and if so, evaluate to the
8510 // field or what the field refers to.
8511 if (Info.CurrentCall && isLambdaCallOperator(Info.CurrentCall->Callee) &&
8512 isa<DeclRefExpr>(E) &&
8513 cast<DeclRefExpr>(E)->refersToEnclosingVariableOrCapture()) {
8514 // We don't always have a complete capture-map when checking or inferring if
8515 // the function call operator meets the requirements of a constexpr function
8516 // - but we don't need to evaluate the captures to determine constexprness
8517 // (dcl.constexpr C++17).
8518 if (Info.checkingPotentialConstantExpression())
8519 return false;
8520
8521 if (auto *FD = Info.CurrentCall->LambdaCaptureFields.lookup(VD)) {
8522 const auto *MD = cast<CXXMethodDecl>(Info.CurrentCall->Callee);
8523
8524 // Static lambda function call operators can't have captures. We already
8525 // diagnosed this, so bail out here.
8526 if (MD->isStatic()) {
8527 assert(Info.CurrentCall->This == nullptr &&
8528 "This should not be set for a static call operator");
8529 return false;
8530 }
8531
8532 // Start with 'Result' referring to the complete closure object...
8533 if (MD->isExplicitObjectMemberFunction()) {
8534 APValue *RefValue =
8535 Info.getParamSlot(Info.CurrentCall->Arguments, MD->getParamDecl(0));
8536 Result.setFrom(Info.Ctx, *RefValue);
8537 } else
8538 Result = *Info.CurrentCall->This;
8539
8540 // ... then update it to refer to the field of the closure object
8541 // that represents the capture.
8542 if (!HandleLValueMember(Info, E, Result, FD))
8543 return false;
8544 // And if the field is of reference type, update 'Result' to refer to what
8545 // the field refers to.
8546 if (FD->getType()->isReferenceType()) {
8547 APValue RVal;
8548 if (!handleLValueToRValueConversion(Info, E, FD->getType(), Result,
8549 RVal))
8550 return false;
8551 Result.setFrom(Info.Ctx, RVal);
8552 }
8553 return true;
8554 }
8555 }
8556
8557 CallStackFrame *Frame = nullptr;
8558 unsigned Version = 0;
8559 if (VD->hasLocalStorage()) {
8560 // Only if a local variable was declared in the function currently being
8561 // evaluated, do we expect to be able to find its value in the current
8562 // frame. (Otherwise it was likely declared in an enclosing context and
8563 // could either have a valid evaluatable value (for e.g. a constexpr
8564 // variable) or be ill-formed (and trigger an appropriate evaluation
8565 // diagnostic)).
8566 CallStackFrame *CurrFrame = Info.CurrentCall;
8567 if (CurrFrame->Callee && CurrFrame->Callee->Equals(VD->getDeclContext())) {
8568 // Function parameters are stored in some caller's frame. (Usually the
8569 // immediate caller, but for an inherited constructor they may be more
8570 // distant.)
8571 if (auto *PVD = dyn_cast<ParmVarDecl>(VD)) {
8572 if (CurrFrame->Arguments) {
8573 VD = CurrFrame->Arguments.getOrigParam(PVD);
8574 Frame =
8575 Info.getCallFrameAndDepth(CurrFrame->Arguments.CallIndex).first;
8576 Version = CurrFrame->Arguments.Version;
8577 }
8578 } else {
8579 Frame = CurrFrame;
8580 Version = CurrFrame->getCurrentTemporaryVersion(VD);
8581 }
8582 }
8583 }
8584
8585 if (!VD->getType()->isReferenceType()) {
8586 if (Frame) {
8587 Result.set({VD, Frame->Index, Version});
8588 return true;
8589 }
8590 return Success(VD);
8591 }
8592
8593 if (!Info.getLangOpts().CPlusPlus11) {
8594 Info.CCEDiag(E, diag::note_constexpr_ltor_non_integral, 1)
8595 << VD << VD->getType();
8596 Info.Note(VD->getLocation(), diag::note_declared_at);
8597 }
8598
8599 APValue *V;
8600 if (!evaluateVarDeclInit(Info, E, VD, Frame, Version, V))
8601 return false;
8602 if (!V->hasValue()) {
8603 // FIXME: Is it possible for V to be indeterminate here? If so, we should
8604 // adjust the diagnostic to say that.
8605 if (!Info.checkingPotentialConstantExpression())
8606 Info.FFDiag(E, diag::note_constexpr_use_uninit_reference);
8607 return false;
8608 }
8609 return Success(*V, E);
8610 }
8611
VisitCallExpr(const CallExpr * E)8612 bool LValueExprEvaluator::VisitCallExpr(const CallExpr *E) {
8613 if (!IsConstantEvaluatedBuiltinCall(E))
8614 return ExprEvaluatorBaseTy::VisitCallExpr(E);
8615
8616 switch (E->getBuiltinCallee()) {
8617 default:
8618 return false;
8619 case Builtin::BIas_const:
8620 case Builtin::BIforward:
8621 case Builtin::BIforward_like:
8622 case Builtin::BImove:
8623 case Builtin::BImove_if_noexcept:
8624 if (cast<FunctionDecl>(E->getCalleeDecl())->isConstexpr())
8625 return Visit(E->getArg(0));
8626 break;
8627 }
8628
8629 return ExprEvaluatorBaseTy::VisitCallExpr(E);
8630 }
8631
VisitMaterializeTemporaryExpr(const MaterializeTemporaryExpr * E)8632 bool LValueExprEvaluator::VisitMaterializeTemporaryExpr(
8633 const MaterializeTemporaryExpr *E) {
8634 // Walk through the expression to find the materialized temporary itself.
8635 SmallVector<const Expr *, 2> CommaLHSs;
8636 SmallVector<SubobjectAdjustment, 2> Adjustments;
8637 const Expr *Inner =
8638 E->getSubExpr()->skipRValueSubobjectAdjustments(CommaLHSs, Adjustments);
8639
8640 // If we passed any comma operators, evaluate their LHSs.
8641 for (const Expr *E : CommaLHSs)
8642 if (!EvaluateIgnoredValue(Info, E))
8643 return false;
8644
8645 // A materialized temporary with static storage duration can appear within the
8646 // result of a constant expression evaluation, so we need to preserve its
8647 // value for use outside this evaluation.
8648 APValue *Value;
8649 if (E->getStorageDuration() == SD_Static) {
8650 if (Info.EvalMode == EvalInfo::EM_ConstantFold)
8651 return false;
8652 // FIXME: What about SD_Thread?
8653 Value = E->getOrCreateValue(true);
8654 *Value = APValue();
8655 Result.set(E);
8656 } else {
8657 Value = &Info.CurrentCall->createTemporary(
8658 E, Inner->getType(),
8659 E->getStorageDuration() == SD_FullExpression ? ScopeKind::FullExpression
8660 : ScopeKind::Block,
8661 Result);
8662 }
8663
8664 QualType Type = Inner->getType();
8665
8666 // Materialize the temporary itself.
8667 if (!EvaluateInPlace(*Value, Info, Result, Inner)) {
8668 *Value = APValue();
8669 return false;
8670 }
8671
8672 // Adjust our lvalue to refer to the desired subobject.
8673 for (unsigned I = Adjustments.size(); I != 0; /**/) {
8674 --I;
8675 switch (Adjustments[I].Kind) {
8676 case SubobjectAdjustment::DerivedToBaseAdjustment:
8677 if (!HandleLValueBasePath(Info, Adjustments[I].DerivedToBase.BasePath,
8678 Type, Result))
8679 return false;
8680 Type = Adjustments[I].DerivedToBase.BasePath->getType();
8681 break;
8682
8683 case SubobjectAdjustment::FieldAdjustment:
8684 if (!HandleLValueMember(Info, E, Result, Adjustments[I].Field))
8685 return false;
8686 Type = Adjustments[I].Field->getType();
8687 break;
8688
8689 case SubobjectAdjustment::MemberPointerAdjustment:
8690 if (!HandleMemberPointerAccess(this->Info, Type, Result,
8691 Adjustments[I].Ptr.RHS))
8692 return false;
8693 Type = Adjustments[I].Ptr.MPT->getPointeeType();
8694 break;
8695 }
8696 }
8697
8698 return true;
8699 }
8700
8701 bool
VisitCompoundLiteralExpr(const CompoundLiteralExpr * E)8702 LValueExprEvaluator::VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) {
8703 assert((!Info.getLangOpts().CPlusPlus || E->isFileScope()) &&
8704 "lvalue compound literal in c++?");
8705 // Defer visiting the literal until the lvalue-to-rvalue conversion. We can
8706 // only see this when folding in C, so there's no standard to follow here.
8707 return Success(E);
8708 }
8709
VisitCXXTypeidExpr(const CXXTypeidExpr * E)8710 bool LValueExprEvaluator::VisitCXXTypeidExpr(const CXXTypeidExpr *E) {
8711 TypeInfoLValue TypeInfo;
8712
8713 if (!E->isPotentiallyEvaluated()) {
8714 if (E->isTypeOperand())
8715 TypeInfo = TypeInfoLValue(E->getTypeOperand(Info.Ctx).getTypePtr());
8716 else
8717 TypeInfo = TypeInfoLValue(E->getExprOperand()->getType().getTypePtr());
8718 } else {
8719 if (!Info.Ctx.getLangOpts().CPlusPlus20) {
8720 Info.CCEDiag(E, diag::note_constexpr_typeid_polymorphic)
8721 << E->getExprOperand()->getType()
8722 << E->getExprOperand()->getSourceRange();
8723 }
8724
8725 if (!Visit(E->getExprOperand()))
8726 return false;
8727
8728 std::optional<DynamicType> DynType =
8729 ComputeDynamicType(Info, E, Result, AK_TypeId);
8730 if (!DynType)
8731 return false;
8732
8733 TypeInfo =
8734 TypeInfoLValue(Info.Ctx.getRecordType(DynType->Type).getTypePtr());
8735 }
8736
8737 return Success(APValue::LValueBase::getTypeInfo(TypeInfo, E->getType()));
8738 }
8739
VisitCXXUuidofExpr(const CXXUuidofExpr * E)8740 bool LValueExprEvaluator::VisitCXXUuidofExpr(const CXXUuidofExpr *E) {
8741 return Success(E->getGuidDecl());
8742 }
8743
VisitMemberExpr(const MemberExpr * E)8744 bool LValueExprEvaluator::VisitMemberExpr(const MemberExpr *E) {
8745 // Handle static data members.
8746 if (const VarDecl *VD = dyn_cast<VarDecl>(E->getMemberDecl())) {
8747 VisitIgnoredBaseExpression(E->getBase());
8748 return VisitVarDecl(E, VD);
8749 }
8750
8751 // Handle static member functions.
8752 if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(E->getMemberDecl())) {
8753 if (MD->isStatic()) {
8754 VisitIgnoredBaseExpression(E->getBase());
8755 return Success(MD);
8756 }
8757 }
8758
8759 // Handle non-static data members.
8760 return LValueExprEvaluatorBaseTy::VisitMemberExpr(E);
8761 }
8762
VisitArraySubscriptExpr(const ArraySubscriptExpr * E)8763 bool LValueExprEvaluator::VisitArraySubscriptExpr(const ArraySubscriptExpr *E) {
8764 // FIXME: Deal with vectors as array subscript bases.
8765 if (E->getBase()->getType()->isVectorType() ||
8766 E->getBase()->getType()->isSveVLSBuiltinType())
8767 return Error(E);
8768
8769 APSInt Index;
8770 bool Success = true;
8771
8772 // C++17's rules require us to evaluate the LHS first, regardless of which
8773 // side is the base.
8774 for (const Expr *SubExpr : {E->getLHS(), E->getRHS()}) {
8775 if (SubExpr == E->getBase() ? !evaluatePointer(SubExpr, Result)
8776 : !EvaluateInteger(SubExpr, Index, Info)) {
8777 if (!Info.noteFailure())
8778 return false;
8779 Success = false;
8780 }
8781 }
8782
8783 return Success &&
8784 HandleLValueArrayAdjustment(Info, E, Result, E->getType(), Index);
8785 }
8786
VisitUnaryDeref(const UnaryOperator * E)8787 bool LValueExprEvaluator::VisitUnaryDeref(const UnaryOperator *E) {
8788 return evaluatePointer(E->getSubExpr(), Result);
8789 }
8790
VisitUnaryReal(const UnaryOperator * E)8791 bool LValueExprEvaluator::VisitUnaryReal(const UnaryOperator *E) {
8792 if (!Visit(E->getSubExpr()))
8793 return false;
8794 // __real is a no-op on scalar lvalues.
8795 if (E->getSubExpr()->getType()->isAnyComplexType())
8796 HandleLValueComplexElement(Info, E, Result, E->getType(), false);
8797 return true;
8798 }
8799
VisitUnaryImag(const UnaryOperator * E)8800 bool LValueExprEvaluator::VisitUnaryImag(const UnaryOperator *E) {
8801 assert(E->getSubExpr()->getType()->isAnyComplexType() &&
8802 "lvalue __imag__ on scalar?");
8803 if (!Visit(E->getSubExpr()))
8804 return false;
8805 HandleLValueComplexElement(Info, E, Result, E->getType(), true);
8806 return true;
8807 }
8808
VisitUnaryPreIncDec(const UnaryOperator * UO)8809 bool LValueExprEvaluator::VisitUnaryPreIncDec(const UnaryOperator *UO) {
8810 if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure())
8811 return Error(UO);
8812
8813 if (!this->Visit(UO->getSubExpr()))
8814 return false;
8815
8816 return handleIncDec(
8817 this->Info, UO, Result, UO->getSubExpr()->getType(),
8818 UO->isIncrementOp(), nullptr);
8819 }
8820
VisitCompoundAssignOperator(const CompoundAssignOperator * CAO)8821 bool LValueExprEvaluator::VisitCompoundAssignOperator(
8822 const CompoundAssignOperator *CAO) {
8823 if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure())
8824 return Error(CAO);
8825
8826 bool Success = true;
8827
8828 // C++17 onwards require that we evaluate the RHS first.
8829 APValue RHS;
8830 if (!Evaluate(RHS, this->Info, CAO->getRHS())) {
8831 if (!Info.noteFailure())
8832 return false;
8833 Success = false;
8834 }
8835
8836 // The overall lvalue result is the result of evaluating the LHS.
8837 if (!this->Visit(CAO->getLHS()) || !Success)
8838 return false;
8839
8840 return handleCompoundAssignment(
8841 this->Info, CAO,
8842 Result, CAO->getLHS()->getType(), CAO->getComputationLHSType(),
8843 CAO->getOpForCompoundAssignment(CAO->getOpcode()), RHS);
8844 }
8845
VisitBinAssign(const BinaryOperator * E)8846 bool LValueExprEvaluator::VisitBinAssign(const BinaryOperator *E) {
8847 if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure())
8848 return Error(E);
8849
8850 bool Success = true;
8851
8852 // C++17 onwards require that we evaluate the RHS first.
8853 APValue NewVal;
8854 if (!Evaluate(NewVal, this->Info, E->getRHS())) {
8855 if (!Info.noteFailure())
8856 return false;
8857 Success = false;
8858 }
8859
8860 if (!this->Visit(E->getLHS()) || !Success)
8861 return false;
8862
8863 if (Info.getLangOpts().CPlusPlus20 &&
8864 !MaybeHandleUnionActiveMemberChange(Info, E->getLHS(), Result))
8865 return false;
8866
8867 return handleAssignment(this->Info, E, Result, E->getLHS()->getType(),
8868 NewVal);
8869 }
8870
8871 //===----------------------------------------------------------------------===//
8872 // Pointer Evaluation
8873 //===----------------------------------------------------------------------===//
8874
8875 /// Attempts to compute the number of bytes available at the pointer
8876 /// returned by a function with the alloc_size attribute. Returns true if we
8877 /// were successful. Places an unsigned number into `Result`.
8878 ///
8879 /// This expects the given CallExpr to be a call to a function with an
8880 /// alloc_size attribute.
getBytesReturnedByAllocSizeCall(const ASTContext & Ctx,const CallExpr * Call,llvm::APInt & Result)8881 static bool getBytesReturnedByAllocSizeCall(const ASTContext &Ctx,
8882 const CallExpr *Call,
8883 llvm::APInt &Result) {
8884 const AllocSizeAttr *AllocSize = getAllocSizeAttr(Call);
8885
8886 assert(AllocSize && AllocSize->getElemSizeParam().isValid());
8887 unsigned SizeArgNo = AllocSize->getElemSizeParam().getASTIndex();
8888 unsigned BitsInSizeT = Ctx.getTypeSize(Ctx.getSizeType());
8889 if (Call->getNumArgs() <= SizeArgNo)
8890 return false;
8891
8892 auto EvaluateAsSizeT = [&](const Expr *E, APSInt &Into) {
8893 Expr::EvalResult ExprResult;
8894 if (!E->EvaluateAsInt(ExprResult, Ctx, Expr::SE_AllowSideEffects))
8895 return false;
8896 Into = ExprResult.Val.getInt();
8897 if (Into.isNegative() || !Into.isIntN(BitsInSizeT))
8898 return false;
8899 Into = Into.zext(BitsInSizeT);
8900 return true;
8901 };
8902
8903 APSInt SizeOfElem;
8904 if (!EvaluateAsSizeT(Call->getArg(SizeArgNo), SizeOfElem))
8905 return false;
8906
8907 if (!AllocSize->getNumElemsParam().isValid()) {
8908 Result = std::move(SizeOfElem);
8909 return true;
8910 }
8911
8912 APSInt NumberOfElems;
8913 unsigned NumArgNo = AllocSize->getNumElemsParam().getASTIndex();
8914 if (!EvaluateAsSizeT(Call->getArg(NumArgNo), NumberOfElems))
8915 return false;
8916
8917 bool Overflow;
8918 llvm::APInt BytesAvailable = SizeOfElem.umul_ov(NumberOfElems, Overflow);
8919 if (Overflow)
8920 return false;
8921
8922 Result = std::move(BytesAvailable);
8923 return true;
8924 }
8925
8926 /// Convenience function. LVal's base must be a call to an alloc_size
8927 /// function.
getBytesReturnedByAllocSizeCall(const ASTContext & Ctx,const LValue & LVal,llvm::APInt & Result)8928 static bool getBytesReturnedByAllocSizeCall(const ASTContext &Ctx,
8929 const LValue &LVal,
8930 llvm::APInt &Result) {
8931 assert(isBaseAnAllocSizeCall(LVal.getLValueBase()) &&
8932 "Can't get the size of a non alloc_size function");
8933 const auto *Base = LVal.getLValueBase().get<const Expr *>();
8934 const CallExpr *CE = tryUnwrapAllocSizeCall(Base);
8935 return getBytesReturnedByAllocSizeCall(Ctx, CE, Result);
8936 }
8937
8938 /// Attempts to evaluate the given LValueBase as the result of a call to
8939 /// a function with the alloc_size attribute. If it was possible to do so, this
8940 /// function will return true, make Result's Base point to said function call,
8941 /// and mark Result's Base as invalid.
evaluateLValueAsAllocSize(EvalInfo & Info,APValue::LValueBase Base,LValue & Result)8942 static bool evaluateLValueAsAllocSize(EvalInfo &Info, APValue::LValueBase Base,
8943 LValue &Result) {
8944 if (Base.isNull())
8945 return false;
8946
8947 // Because we do no form of static analysis, we only support const variables.
8948 //
8949 // Additionally, we can't support parameters, nor can we support static
8950 // variables (in the latter case, use-before-assign isn't UB; in the former,
8951 // we have no clue what they'll be assigned to).
8952 const auto *VD =
8953 dyn_cast_or_null<VarDecl>(Base.dyn_cast<const ValueDecl *>());
8954 if (!VD || !VD->isLocalVarDecl() || !VD->getType().isConstQualified())
8955 return false;
8956
8957 const Expr *Init = VD->getAnyInitializer();
8958 if (!Init || Init->getType().isNull())
8959 return false;
8960
8961 const Expr *E = Init->IgnoreParens();
8962 if (!tryUnwrapAllocSizeCall(E))
8963 return false;
8964
8965 // Store E instead of E unwrapped so that the type of the LValue's base is
8966 // what the user wanted.
8967 Result.setInvalid(E);
8968
8969 QualType Pointee = E->getType()->castAs<PointerType>()->getPointeeType();
8970 Result.addUnsizedArray(Info, E, Pointee);
8971 return true;
8972 }
8973
8974 namespace {
8975 class PointerExprEvaluator
8976 : public ExprEvaluatorBase<PointerExprEvaluator> {
8977 LValue &Result;
8978 bool InvalidBaseOK;
8979
Success(const Expr * E)8980 bool Success(const Expr *E) {
8981 Result.set(E);
8982 return true;
8983 }
8984
evaluateLValue(const Expr * E,LValue & Result)8985 bool evaluateLValue(const Expr *E, LValue &Result) {
8986 return EvaluateLValue(E, Result, Info, InvalidBaseOK);
8987 }
8988
evaluatePointer(const Expr * E,LValue & Result)8989 bool evaluatePointer(const Expr *E, LValue &Result) {
8990 return EvaluatePointer(E, Result, Info, InvalidBaseOK);
8991 }
8992
8993 bool visitNonBuiltinCallExpr(const CallExpr *E);
8994 public:
8995
PointerExprEvaluator(EvalInfo & info,LValue & Result,bool InvalidBaseOK)8996 PointerExprEvaluator(EvalInfo &info, LValue &Result, bool InvalidBaseOK)
8997 : ExprEvaluatorBaseTy(info), Result(Result),
8998 InvalidBaseOK(InvalidBaseOK) {}
8999
Success(const APValue & V,const Expr * E)9000 bool Success(const APValue &V, const Expr *E) {
9001 Result.setFrom(Info.Ctx, V);
9002 return true;
9003 }
ZeroInitialization(const Expr * E)9004 bool ZeroInitialization(const Expr *E) {
9005 Result.setNull(Info.Ctx, E->getType());
9006 return true;
9007 }
9008
9009 bool VisitBinaryOperator(const BinaryOperator *E);
9010 bool VisitCastExpr(const CastExpr* E);
9011 bool VisitUnaryAddrOf(const UnaryOperator *E);
VisitObjCStringLiteral(const ObjCStringLiteral * E)9012 bool VisitObjCStringLiteral(const ObjCStringLiteral *E)
9013 { return Success(E); }
VisitObjCBoxedExpr(const ObjCBoxedExpr * E)9014 bool VisitObjCBoxedExpr(const ObjCBoxedExpr *E) {
9015 if (E->isExpressibleAsConstantInitializer())
9016 return Success(E);
9017 if (Info.noteFailure())
9018 EvaluateIgnoredValue(Info, E->getSubExpr());
9019 return Error(E);
9020 }
VisitAddrLabelExpr(const AddrLabelExpr * E)9021 bool VisitAddrLabelExpr(const AddrLabelExpr *E)
9022 { return Success(E); }
9023 bool VisitCallExpr(const CallExpr *E);
9024 bool VisitBuiltinCallExpr(const CallExpr *E, unsigned BuiltinOp);
VisitBlockExpr(const BlockExpr * E)9025 bool VisitBlockExpr(const BlockExpr *E) {
9026 if (!E->getBlockDecl()->hasCaptures())
9027 return Success(E);
9028 return Error(E);
9029 }
VisitCXXThisExpr(const CXXThisExpr * E)9030 bool VisitCXXThisExpr(const CXXThisExpr *E) {
9031 // Can't look at 'this' when checking a potential constant expression.
9032 if (Info.checkingPotentialConstantExpression())
9033 return false;
9034 if (!Info.CurrentCall->This) {
9035 if (Info.getLangOpts().CPlusPlus11)
9036 Info.FFDiag(E, diag::note_constexpr_this) << E->isImplicit();
9037 else
9038 Info.FFDiag(E);
9039 return false;
9040 }
9041 Result = *Info.CurrentCall->This;
9042
9043 if (isLambdaCallOperator(Info.CurrentCall->Callee)) {
9044 // Ensure we actually have captured 'this'. If something was wrong with
9045 // 'this' capture, the error would have been previously reported.
9046 // Otherwise we can be inside of a default initialization of an object
9047 // declared by lambda's body, so no need to return false.
9048 if (!Info.CurrentCall->LambdaThisCaptureField)
9049 return true;
9050
9051 // If we have captured 'this', the 'this' expression refers
9052 // to the enclosing '*this' object (either by value or reference) which is
9053 // either copied into the closure object's field that represents the
9054 // '*this' or refers to '*this'.
9055 // Update 'Result' to refer to the data member/field of the closure object
9056 // that represents the '*this' capture.
9057 if (!HandleLValueMember(Info, E, Result,
9058 Info.CurrentCall->LambdaThisCaptureField))
9059 return false;
9060 // If we captured '*this' by reference, replace the field with its referent.
9061 if (Info.CurrentCall->LambdaThisCaptureField->getType()
9062 ->isPointerType()) {
9063 APValue RVal;
9064 if (!handleLValueToRValueConversion(Info, E, E->getType(), Result,
9065 RVal))
9066 return false;
9067
9068 Result.setFrom(Info.Ctx, RVal);
9069 }
9070 }
9071 return true;
9072 }
9073
9074 bool VisitCXXNewExpr(const CXXNewExpr *E);
9075
VisitSourceLocExpr(const SourceLocExpr * E)9076 bool VisitSourceLocExpr(const SourceLocExpr *E) {
9077 assert(!E->isIntType() && "SourceLocExpr isn't a pointer type?");
9078 APValue LValResult = E->EvaluateInContext(
9079 Info.Ctx, Info.CurrentCall->CurSourceLocExprScope.getDefaultExpr());
9080 Result.setFrom(Info.Ctx, LValResult);
9081 return true;
9082 }
9083
VisitSYCLUniqueStableNameExpr(const SYCLUniqueStableNameExpr * E)9084 bool VisitSYCLUniqueStableNameExpr(const SYCLUniqueStableNameExpr *E) {
9085 std::string ResultStr = E->ComputeName(Info.Ctx);
9086
9087 QualType CharTy = Info.Ctx.CharTy.withConst();
9088 APInt Size(Info.Ctx.getTypeSize(Info.Ctx.getSizeType()),
9089 ResultStr.size() + 1);
9090 QualType ArrayTy = Info.Ctx.getConstantArrayType(
9091 CharTy, Size, nullptr, ArraySizeModifier::Normal, 0);
9092
9093 StringLiteral *SL =
9094 StringLiteral::Create(Info.Ctx, ResultStr, StringLiteralKind::Ordinary,
9095 /*Pascal*/ false, ArrayTy, E->getLocation());
9096
9097 evaluateLValue(SL, Result);
9098 Result.addArray(Info, E, cast<ConstantArrayType>(ArrayTy));
9099 return true;
9100 }
9101
9102 // FIXME: Missing: @protocol, @selector
9103 };
9104 } // end anonymous namespace
9105
EvaluatePointer(const Expr * E,LValue & Result,EvalInfo & Info,bool InvalidBaseOK)9106 static bool EvaluatePointer(const Expr* E, LValue& Result, EvalInfo &Info,
9107 bool InvalidBaseOK) {
9108 assert(!E->isValueDependent());
9109 assert(E->isPRValue() && E->getType()->hasPointerRepresentation());
9110 return PointerExprEvaluator(Info, Result, InvalidBaseOK).Visit(E);
9111 }
9112
VisitBinaryOperator(const BinaryOperator * E)9113 bool PointerExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
9114 if (E->getOpcode() != BO_Add &&
9115 E->getOpcode() != BO_Sub)
9116 return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
9117
9118 const Expr *PExp = E->getLHS();
9119 const Expr *IExp = E->getRHS();
9120 if (IExp->getType()->isPointerType())
9121 std::swap(PExp, IExp);
9122
9123 bool EvalPtrOK = evaluatePointer(PExp, Result);
9124 if (!EvalPtrOK && !Info.noteFailure())
9125 return false;
9126
9127 llvm::APSInt Offset;
9128 if (!EvaluateInteger(IExp, Offset, Info) || !EvalPtrOK)
9129 return false;
9130
9131 if (E->getOpcode() == BO_Sub)
9132 negateAsSigned(Offset);
9133
9134 QualType Pointee = PExp->getType()->castAs<PointerType>()->getPointeeType();
9135 return HandleLValueArrayAdjustment(Info, E, Result, Pointee, Offset);
9136 }
9137
VisitUnaryAddrOf(const UnaryOperator * E)9138 bool PointerExprEvaluator::VisitUnaryAddrOf(const UnaryOperator *E) {
9139 return evaluateLValue(E->getSubExpr(), Result);
9140 }
9141
9142 // Is the provided decl 'std::source_location::current'?
IsDeclSourceLocationCurrent(const FunctionDecl * FD)9143 static bool IsDeclSourceLocationCurrent(const FunctionDecl *FD) {
9144 if (!FD)
9145 return false;
9146 const IdentifierInfo *FnII = FD->getIdentifier();
9147 if (!FnII || !FnII->isStr("current"))
9148 return false;
9149
9150 const auto *RD = dyn_cast<RecordDecl>(FD->getParent());
9151 if (!RD)
9152 return false;
9153
9154 const IdentifierInfo *ClassII = RD->getIdentifier();
9155 return RD->isInStdNamespace() && ClassII && ClassII->isStr("source_location");
9156 }
9157
VisitCastExpr(const CastExpr * E)9158 bool PointerExprEvaluator::VisitCastExpr(const CastExpr *E) {
9159 const Expr *SubExpr = E->getSubExpr();
9160
9161 switch (E->getCastKind()) {
9162 default:
9163 break;
9164 case CK_BitCast:
9165 case CK_CPointerToObjCPointerCast:
9166 case CK_BlockPointerToObjCPointerCast:
9167 case CK_AnyPointerToBlockPointerCast:
9168 case CK_AddressSpaceConversion:
9169 if (!Visit(SubExpr))
9170 return false;
9171 // Bitcasts to cv void* are static_casts, not reinterpret_casts, so are
9172 // permitted in constant expressions in C++11. Bitcasts from cv void* are
9173 // also static_casts, but we disallow them as a resolution to DR1312.
9174 if (!E->getType()->isVoidPointerType()) {
9175 // In some circumstances, we permit casting from void* to cv1 T*, when the
9176 // actual pointee object is actually a cv2 T.
9177 bool HasValidResult = !Result.InvalidBase && !Result.Designator.Invalid &&
9178 !Result.IsNullPtr;
9179 bool VoidPtrCastMaybeOK =
9180 HasValidResult &&
9181 Info.Ctx.hasSameUnqualifiedType(Result.Designator.getType(Info.Ctx),
9182 E->getType()->getPointeeType());
9183 // 1. We'll allow it in std::allocator::allocate, and anything which that
9184 // calls.
9185 // 2. HACK 2022-03-28: Work around an issue with libstdc++'s
9186 // <source_location> header. Fixed in GCC 12 and later (2022-04-??).
9187 // We'll allow it in the body of std::source_location::current. GCC's
9188 // implementation had a parameter of type `void*`, and casts from
9189 // that back to `const __impl*` in its body.
9190 if (VoidPtrCastMaybeOK &&
9191 (Info.getStdAllocatorCaller("allocate") ||
9192 IsDeclSourceLocationCurrent(Info.CurrentCall->Callee) ||
9193 Info.getLangOpts().CPlusPlus26)) {
9194 // Permitted.
9195 } else {
9196 if (SubExpr->getType()->isVoidPointerType()) {
9197 if (HasValidResult)
9198 CCEDiag(E, diag::note_constexpr_invalid_void_star_cast)
9199 << SubExpr->getType() << Info.getLangOpts().CPlusPlus26
9200 << Result.Designator.getType(Info.Ctx).getCanonicalType()
9201 << E->getType()->getPointeeType();
9202 else
9203 CCEDiag(E, diag::note_constexpr_invalid_cast)
9204 << 3 << SubExpr->getType();
9205 } else
9206 CCEDiag(E, diag::note_constexpr_invalid_cast)
9207 << 2 << Info.Ctx.getLangOpts().CPlusPlus;
9208 Result.Designator.setInvalid();
9209 }
9210 }
9211 if (E->getCastKind() == CK_AddressSpaceConversion && Result.IsNullPtr)
9212 ZeroInitialization(E);
9213 return true;
9214
9215 case CK_DerivedToBase:
9216 case CK_UncheckedDerivedToBase:
9217 if (!evaluatePointer(E->getSubExpr(), Result))
9218 return false;
9219 if (!Result.Base && Result.Offset.isZero())
9220 return true;
9221
9222 // Now figure out the necessary offset to add to the base LV to get from
9223 // the derived class to the base class.
9224 return HandleLValueBasePath(Info, E, E->getSubExpr()->getType()->
9225 castAs<PointerType>()->getPointeeType(),
9226 Result);
9227
9228 case CK_BaseToDerived:
9229 if (!Visit(E->getSubExpr()))
9230 return false;
9231 if (!Result.Base && Result.Offset.isZero())
9232 return true;
9233 return HandleBaseToDerivedCast(Info, E, Result);
9234
9235 case CK_Dynamic:
9236 if (!Visit(E->getSubExpr()))
9237 return false;
9238 return HandleDynamicCast(Info, cast<ExplicitCastExpr>(E), Result);
9239
9240 case CK_NullToPointer:
9241 VisitIgnoredValue(E->getSubExpr());
9242 return ZeroInitialization(E);
9243
9244 case CK_IntegralToPointer: {
9245 CCEDiag(E, diag::note_constexpr_invalid_cast)
9246 << 2 << Info.Ctx.getLangOpts().CPlusPlus;
9247
9248 APValue Value;
9249 if (!EvaluateIntegerOrLValue(SubExpr, Value, Info))
9250 break;
9251
9252 if (Value.isInt()) {
9253 unsigned Size = Info.Ctx.getTypeSize(E->getType());
9254 uint64_t N = Value.getInt().extOrTrunc(Size).getZExtValue();
9255 Result.Base = (Expr*)nullptr;
9256 Result.InvalidBase = false;
9257 Result.Offset = CharUnits::fromQuantity(N);
9258 Result.Designator.setInvalid();
9259 Result.IsNullPtr = false;
9260 return true;
9261 } else {
9262 // Cast is of an lvalue, no need to change value.
9263 Result.setFrom(Info.Ctx, Value);
9264 return true;
9265 }
9266 }
9267
9268 case CK_ArrayToPointerDecay: {
9269 if (SubExpr->isGLValue()) {
9270 if (!evaluateLValue(SubExpr, Result))
9271 return false;
9272 } else {
9273 APValue &Value = Info.CurrentCall->createTemporary(
9274 SubExpr, SubExpr->getType(), ScopeKind::FullExpression, Result);
9275 if (!EvaluateInPlace(Value, Info, Result, SubExpr))
9276 return false;
9277 }
9278 // The result is a pointer to the first element of the array.
9279 auto *AT = Info.Ctx.getAsArrayType(SubExpr->getType());
9280 if (auto *CAT = dyn_cast<ConstantArrayType>(AT))
9281 Result.addArray(Info, E, CAT);
9282 else
9283 Result.addUnsizedArray(Info, E, AT->getElementType());
9284 return true;
9285 }
9286
9287 case CK_FunctionToPointerDecay:
9288 return evaluateLValue(SubExpr, Result);
9289
9290 case CK_LValueToRValue: {
9291 LValue LVal;
9292 if (!evaluateLValue(E->getSubExpr(), LVal))
9293 return false;
9294
9295 APValue RVal;
9296 // Note, we use the subexpression's type in order to retain cv-qualifiers.
9297 if (!handleLValueToRValueConversion(Info, E, E->getSubExpr()->getType(),
9298 LVal, RVal))
9299 return InvalidBaseOK &&
9300 evaluateLValueAsAllocSize(Info, LVal.Base, Result);
9301 return Success(RVal, E);
9302 }
9303 }
9304
9305 return ExprEvaluatorBaseTy::VisitCastExpr(E);
9306 }
9307
GetAlignOfType(EvalInfo & Info,QualType T,UnaryExprOrTypeTrait ExprKind)9308 static CharUnits GetAlignOfType(EvalInfo &Info, QualType T,
9309 UnaryExprOrTypeTrait ExprKind) {
9310 // C++ [expr.alignof]p3:
9311 // When alignof is applied to a reference type, the result is the
9312 // alignment of the referenced type.
9313 T = T.getNonReferenceType();
9314
9315 if (T.getQualifiers().hasUnaligned())
9316 return CharUnits::One();
9317
9318 const bool AlignOfReturnsPreferred =
9319 Info.Ctx.getLangOpts().getClangABICompat() <= LangOptions::ClangABI::Ver7;
9320
9321 // __alignof is defined to return the preferred alignment.
9322 // Before 8, clang returned the preferred alignment for alignof and _Alignof
9323 // as well.
9324 if (ExprKind == UETT_PreferredAlignOf || AlignOfReturnsPreferred)
9325 return Info.Ctx.toCharUnitsFromBits(
9326 Info.Ctx.getPreferredTypeAlign(T.getTypePtr()));
9327 // alignof and _Alignof are defined to return the ABI alignment.
9328 else if (ExprKind == UETT_AlignOf)
9329 return Info.Ctx.getTypeAlignInChars(T.getTypePtr());
9330 else
9331 llvm_unreachable("GetAlignOfType on a non-alignment ExprKind");
9332 }
9333
GetAlignOfExpr(EvalInfo & Info,const Expr * E,UnaryExprOrTypeTrait ExprKind)9334 static CharUnits GetAlignOfExpr(EvalInfo &Info, const Expr *E,
9335 UnaryExprOrTypeTrait ExprKind) {
9336 E = E->IgnoreParens();
9337
9338 // The kinds of expressions that we have special-case logic here for
9339 // should be kept up to date with the special checks for those
9340 // expressions in Sema.
9341
9342 // alignof decl is always accepted, even if it doesn't make sense: we default
9343 // to 1 in those cases.
9344 if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
9345 return Info.Ctx.getDeclAlign(DRE->getDecl(),
9346 /*RefAsPointee*/true);
9347
9348 if (const MemberExpr *ME = dyn_cast<MemberExpr>(E))
9349 return Info.Ctx.getDeclAlign(ME->getMemberDecl(),
9350 /*RefAsPointee*/true);
9351
9352 return GetAlignOfType(Info, E->getType(), ExprKind);
9353 }
9354
getBaseAlignment(EvalInfo & Info,const LValue & Value)9355 static CharUnits getBaseAlignment(EvalInfo &Info, const LValue &Value) {
9356 if (const auto *VD = Value.Base.dyn_cast<const ValueDecl *>())
9357 return Info.Ctx.getDeclAlign(VD);
9358 if (const auto *E = Value.Base.dyn_cast<const Expr *>())
9359 return GetAlignOfExpr(Info, E, UETT_AlignOf);
9360 return GetAlignOfType(Info, Value.Base.getTypeInfoType(), UETT_AlignOf);
9361 }
9362
9363 /// Evaluate the value of the alignment argument to __builtin_align_{up,down},
9364 /// __builtin_is_aligned and __builtin_assume_aligned.
getAlignmentArgument(const Expr * E,QualType ForType,EvalInfo & Info,APSInt & Alignment)9365 static bool getAlignmentArgument(const Expr *E, QualType ForType,
9366 EvalInfo &Info, APSInt &Alignment) {
9367 if (!EvaluateInteger(E, Alignment, Info))
9368 return false;
9369 if (Alignment < 0 || !Alignment.isPowerOf2()) {
9370 Info.FFDiag(E, diag::note_constexpr_invalid_alignment) << Alignment;
9371 return false;
9372 }
9373 unsigned SrcWidth = Info.Ctx.getIntWidth(ForType);
9374 APSInt MaxValue(APInt::getOneBitSet(SrcWidth, SrcWidth - 1));
9375 if (APSInt::compareValues(Alignment, MaxValue) > 0) {
9376 Info.FFDiag(E, diag::note_constexpr_alignment_too_big)
9377 << MaxValue << ForType << Alignment;
9378 return false;
9379 }
9380 // Ensure both alignment and source value have the same bit width so that we
9381 // don't assert when computing the resulting value.
9382 APSInt ExtAlignment =
9383 APSInt(Alignment.zextOrTrunc(SrcWidth), /*isUnsigned=*/true);
9384 assert(APSInt::compareValues(Alignment, ExtAlignment) == 0 &&
9385 "Alignment should not be changed by ext/trunc");
9386 Alignment = ExtAlignment;
9387 assert(Alignment.getBitWidth() == SrcWidth);
9388 return true;
9389 }
9390
9391 // To be clear: this happily visits unsupported builtins. Better name welcomed.
visitNonBuiltinCallExpr(const CallExpr * E)9392 bool PointerExprEvaluator::visitNonBuiltinCallExpr(const CallExpr *E) {
9393 if (ExprEvaluatorBaseTy::VisitCallExpr(E))
9394 return true;
9395
9396 if (!(InvalidBaseOK && getAllocSizeAttr(E)))
9397 return false;
9398
9399 Result.setInvalid(E);
9400 QualType PointeeTy = E->getType()->castAs<PointerType>()->getPointeeType();
9401 Result.addUnsizedArray(Info, E, PointeeTy);
9402 return true;
9403 }
9404
VisitCallExpr(const CallExpr * E)9405 bool PointerExprEvaluator::VisitCallExpr(const CallExpr *E) {
9406 if (!IsConstantEvaluatedBuiltinCall(E))
9407 return visitNonBuiltinCallExpr(E);
9408 return VisitBuiltinCallExpr(E, E->getBuiltinCallee());
9409 }
9410
9411 // Determine if T is a character type for which we guarantee that
9412 // sizeof(T) == 1.
isOneByteCharacterType(QualType T)9413 static bool isOneByteCharacterType(QualType T) {
9414 return T->isCharType() || T->isChar8Type();
9415 }
9416
VisitBuiltinCallExpr(const CallExpr * E,unsigned BuiltinOp)9417 bool PointerExprEvaluator::VisitBuiltinCallExpr(const CallExpr *E,
9418 unsigned BuiltinOp) {
9419 if (IsNoOpCall(E))
9420 return Success(E);
9421
9422 switch (BuiltinOp) {
9423 case Builtin::BIaddressof:
9424 case Builtin::BI__addressof:
9425 case Builtin::BI__builtin_addressof:
9426 return evaluateLValue(E->getArg(0), Result);
9427 case Builtin::BI__builtin_assume_aligned: {
9428 // We need to be very careful here because: if the pointer does not have the
9429 // asserted alignment, then the behavior is undefined, and undefined
9430 // behavior is non-constant.
9431 if (!evaluatePointer(E->getArg(0), Result))
9432 return false;
9433
9434 LValue OffsetResult(Result);
9435 APSInt Alignment;
9436 if (!getAlignmentArgument(E->getArg(1), E->getArg(0)->getType(), Info,
9437 Alignment))
9438 return false;
9439 CharUnits Align = CharUnits::fromQuantity(Alignment.getZExtValue());
9440
9441 if (E->getNumArgs() > 2) {
9442 APSInt Offset;
9443 if (!EvaluateInteger(E->getArg(2), Offset, Info))
9444 return false;
9445
9446 int64_t AdditionalOffset = -Offset.getZExtValue();
9447 OffsetResult.Offset += CharUnits::fromQuantity(AdditionalOffset);
9448 }
9449
9450 // If there is a base object, then it must have the correct alignment.
9451 if (OffsetResult.Base) {
9452 CharUnits BaseAlignment = getBaseAlignment(Info, OffsetResult);
9453
9454 if (BaseAlignment < Align) {
9455 Result.Designator.setInvalid();
9456 // FIXME: Add support to Diagnostic for long / long long.
9457 CCEDiag(E->getArg(0),
9458 diag::note_constexpr_baa_insufficient_alignment) << 0
9459 << (unsigned)BaseAlignment.getQuantity()
9460 << (unsigned)Align.getQuantity();
9461 return false;
9462 }
9463 }
9464
9465 // The offset must also have the correct alignment.
9466 if (OffsetResult.Offset.alignTo(Align) != OffsetResult.Offset) {
9467 Result.Designator.setInvalid();
9468
9469 (OffsetResult.Base
9470 ? CCEDiag(E->getArg(0),
9471 diag::note_constexpr_baa_insufficient_alignment) << 1
9472 : CCEDiag(E->getArg(0),
9473 diag::note_constexpr_baa_value_insufficient_alignment))
9474 << (int)OffsetResult.Offset.getQuantity()
9475 << (unsigned)Align.getQuantity();
9476 return false;
9477 }
9478
9479 return true;
9480 }
9481 case Builtin::BI__builtin_align_up:
9482 case Builtin::BI__builtin_align_down: {
9483 if (!evaluatePointer(E->getArg(0), Result))
9484 return false;
9485 APSInt Alignment;
9486 if (!getAlignmentArgument(E->getArg(1), E->getArg(0)->getType(), Info,
9487 Alignment))
9488 return false;
9489 CharUnits BaseAlignment = getBaseAlignment(Info, Result);
9490 CharUnits PtrAlign = BaseAlignment.alignmentAtOffset(Result.Offset);
9491 // For align_up/align_down, we can return the same value if the alignment
9492 // is known to be greater or equal to the requested value.
9493 if (PtrAlign.getQuantity() >= Alignment)
9494 return true;
9495
9496 // The alignment could be greater than the minimum at run-time, so we cannot
9497 // infer much about the resulting pointer value. One case is possible:
9498 // For `_Alignas(32) char buf[N]; __builtin_align_down(&buf[idx], 32)` we
9499 // can infer the correct index if the requested alignment is smaller than
9500 // the base alignment so we can perform the computation on the offset.
9501 if (BaseAlignment.getQuantity() >= Alignment) {
9502 assert(Alignment.getBitWidth() <= 64 &&
9503 "Cannot handle > 64-bit address-space");
9504 uint64_t Alignment64 = Alignment.getZExtValue();
9505 CharUnits NewOffset = CharUnits::fromQuantity(
9506 BuiltinOp == Builtin::BI__builtin_align_down
9507 ? llvm::alignDown(Result.Offset.getQuantity(), Alignment64)
9508 : llvm::alignTo(Result.Offset.getQuantity(), Alignment64));
9509 Result.adjustOffset(NewOffset - Result.Offset);
9510 // TODO: diagnose out-of-bounds values/only allow for arrays?
9511 return true;
9512 }
9513 // Otherwise, we cannot constant-evaluate the result.
9514 Info.FFDiag(E->getArg(0), diag::note_constexpr_alignment_adjust)
9515 << Alignment;
9516 return false;
9517 }
9518 case Builtin::BI__builtin_operator_new:
9519 return HandleOperatorNewCall(Info, E, Result);
9520 case Builtin::BI__builtin_launder:
9521 return evaluatePointer(E->getArg(0), Result);
9522 case Builtin::BIstrchr:
9523 case Builtin::BIwcschr:
9524 case Builtin::BImemchr:
9525 case Builtin::BIwmemchr:
9526 if (Info.getLangOpts().CPlusPlus11)
9527 Info.CCEDiag(E, diag::note_constexpr_invalid_function)
9528 << /*isConstexpr*/ 0 << /*isConstructor*/ 0
9529 << ("'" + Info.Ctx.BuiltinInfo.getName(BuiltinOp) + "'").str();
9530 else
9531 Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr);
9532 [[fallthrough]];
9533 case Builtin::BI__builtin_strchr:
9534 case Builtin::BI__builtin_wcschr:
9535 case Builtin::BI__builtin_memchr:
9536 case Builtin::BI__builtin_char_memchr:
9537 case Builtin::BI__builtin_wmemchr: {
9538 if (!Visit(E->getArg(0)))
9539 return false;
9540 APSInt Desired;
9541 if (!EvaluateInteger(E->getArg(1), Desired, Info))
9542 return false;
9543 uint64_t MaxLength = uint64_t(-1);
9544 if (BuiltinOp != Builtin::BIstrchr &&
9545 BuiltinOp != Builtin::BIwcschr &&
9546 BuiltinOp != Builtin::BI__builtin_strchr &&
9547 BuiltinOp != Builtin::BI__builtin_wcschr) {
9548 APSInt N;
9549 if (!EvaluateInteger(E->getArg(2), N, Info))
9550 return false;
9551 MaxLength = N.getZExtValue();
9552 }
9553 // We cannot find the value if there are no candidates to match against.
9554 if (MaxLength == 0u)
9555 return ZeroInitialization(E);
9556 if (!Result.checkNullPointerForFoldAccess(Info, E, AK_Read) ||
9557 Result.Designator.Invalid)
9558 return false;
9559 QualType CharTy = Result.Designator.getType(Info.Ctx);
9560 bool IsRawByte = BuiltinOp == Builtin::BImemchr ||
9561 BuiltinOp == Builtin::BI__builtin_memchr;
9562 assert(IsRawByte ||
9563 Info.Ctx.hasSameUnqualifiedType(
9564 CharTy, E->getArg(0)->getType()->getPointeeType()));
9565 // Pointers to const void may point to objects of incomplete type.
9566 if (IsRawByte && CharTy->isIncompleteType()) {
9567 Info.FFDiag(E, diag::note_constexpr_ltor_incomplete_type) << CharTy;
9568 return false;
9569 }
9570 // Give up on byte-oriented matching against multibyte elements.
9571 // FIXME: We can compare the bytes in the correct order.
9572 if (IsRawByte && !isOneByteCharacterType(CharTy)) {
9573 Info.FFDiag(E, diag::note_constexpr_memchr_unsupported)
9574 << ("'" + Info.Ctx.BuiltinInfo.getName(BuiltinOp) + "'").str()
9575 << CharTy;
9576 return false;
9577 }
9578 // Figure out what value we're actually looking for (after converting to
9579 // the corresponding unsigned type if necessary).
9580 uint64_t DesiredVal;
9581 bool StopAtNull = false;
9582 switch (BuiltinOp) {
9583 case Builtin::BIstrchr:
9584 case Builtin::BI__builtin_strchr:
9585 // strchr compares directly to the passed integer, and therefore
9586 // always fails if given an int that is not a char.
9587 if (!APSInt::isSameValue(HandleIntToIntCast(Info, E, CharTy,
9588 E->getArg(1)->getType(),
9589 Desired),
9590 Desired))
9591 return ZeroInitialization(E);
9592 StopAtNull = true;
9593 [[fallthrough]];
9594 case Builtin::BImemchr:
9595 case Builtin::BI__builtin_memchr:
9596 case Builtin::BI__builtin_char_memchr:
9597 // memchr compares by converting both sides to unsigned char. That's also
9598 // correct for strchr if we get this far (to cope with plain char being
9599 // unsigned in the strchr case).
9600 DesiredVal = Desired.trunc(Info.Ctx.getCharWidth()).getZExtValue();
9601 break;
9602
9603 case Builtin::BIwcschr:
9604 case Builtin::BI__builtin_wcschr:
9605 StopAtNull = true;
9606 [[fallthrough]];
9607 case Builtin::BIwmemchr:
9608 case Builtin::BI__builtin_wmemchr:
9609 // wcschr and wmemchr are given a wchar_t to look for. Just use it.
9610 DesiredVal = Desired.getZExtValue();
9611 break;
9612 }
9613
9614 for (; MaxLength; --MaxLength) {
9615 APValue Char;
9616 if (!handleLValueToRValueConversion(Info, E, CharTy, Result, Char) ||
9617 !Char.isInt())
9618 return false;
9619 if (Char.getInt().getZExtValue() == DesiredVal)
9620 return true;
9621 if (StopAtNull && !Char.getInt())
9622 break;
9623 if (!HandleLValueArrayAdjustment(Info, E, Result, CharTy, 1))
9624 return false;
9625 }
9626 // Not found: return nullptr.
9627 return ZeroInitialization(E);
9628 }
9629
9630 case Builtin::BImemcpy:
9631 case Builtin::BImemmove:
9632 case Builtin::BIwmemcpy:
9633 case Builtin::BIwmemmove:
9634 if (Info.getLangOpts().CPlusPlus11)
9635 Info.CCEDiag(E, diag::note_constexpr_invalid_function)
9636 << /*isConstexpr*/ 0 << /*isConstructor*/ 0
9637 << ("'" + Info.Ctx.BuiltinInfo.getName(BuiltinOp) + "'").str();
9638 else
9639 Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr);
9640 [[fallthrough]];
9641 case Builtin::BI__builtin_memcpy:
9642 case Builtin::BI__builtin_memmove:
9643 case Builtin::BI__builtin_wmemcpy:
9644 case Builtin::BI__builtin_wmemmove: {
9645 bool WChar = BuiltinOp == Builtin::BIwmemcpy ||
9646 BuiltinOp == Builtin::BIwmemmove ||
9647 BuiltinOp == Builtin::BI__builtin_wmemcpy ||
9648 BuiltinOp == Builtin::BI__builtin_wmemmove;
9649 bool Move = BuiltinOp == Builtin::BImemmove ||
9650 BuiltinOp == Builtin::BIwmemmove ||
9651 BuiltinOp == Builtin::BI__builtin_memmove ||
9652 BuiltinOp == Builtin::BI__builtin_wmemmove;
9653
9654 // The result of mem* is the first argument.
9655 if (!Visit(E->getArg(0)))
9656 return false;
9657 LValue Dest = Result;
9658
9659 LValue Src;
9660 if (!EvaluatePointer(E->getArg(1), Src, Info))
9661 return false;
9662
9663 APSInt N;
9664 if (!EvaluateInteger(E->getArg(2), N, Info))
9665 return false;
9666 assert(!N.isSigned() && "memcpy and friends take an unsigned size");
9667
9668 // If the size is zero, we treat this as always being a valid no-op.
9669 // (Even if one of the src and dest pointers is null.)
9670 if (!N)
9671 return true;
9672
9673 // Otherwise, if either of the operands is null, we can't proceed. Don't
9674 // try to determine the type of the copied objects, because there aren't
9675 // any.
9676 if (!Src.Base || !Dest.Base) {
9677 APValue Val;
9678 (!Src.Base ? Src : Dest).moveInto(Val);
9679 Info.FFDiag(E, diag::note_constexpr_memcpy_null)
9680 << Move << WChar << !!Src.Base
9681 << Val.getAsString(Info.Ctx, E->getArg(0)->getType());
9682 return false;
9683 }
9684 if (Src.Designator.Invalid || Dest.Designator.Invalid)
9685 return false;
9686
9687 // We require that Src and Dest are both pointers to arrays of
9688 // trivially-copyable type. (For the wide version, the designator will be
9689 // invalid if the designated object is not a wchar_t.)
9690 QualType T = Dest.Designator.getType(Info.Ctx);
9691 QualType SrcT = Src.Designator.getType(Info.Ctx);
9692 if (!Info.Ctx.hasSameUnqualifiedType(T, SrcT)) {
9693 // FIXME: Consider using our bit_cast implementation to support this.
9694 Info.FFDiag(E, diag::note_constexpr_memcpy_type_pun) << Move << SrcT << T;
9695 return false;
9696 }
9697 if (T->isIncompleteType()) {
9698 Info.FFDiag(E, diag::note_constexpr_memcpy_incomplete_type) << Move << T;
9699 return false;
9700 }
9701 if (!T.isTriviallyCopyableType(Info.Ctx)) {
9702 Info.FFDiag(E, diag::note_constexpr_memcpy_nontrivial) << Move << T;
9703 return false;
9704 }
9705
9706 // Figure out how many T's we're copying.
9707 uint64_t TSize = Info.Ctx.getTypeSizeInChars(T).getQuantity();
9708 if (TSize == 0)
9709 return false;
9710 if (!WChar) {
9711 uint64_t Remainder;
9712 llvm::APInt OrigN = N;
9713 llvm::APInt::udivrem(OrigN, TSize, N, Remainder);
9714 if (Remainder) {
9715 Info.FFDiag(E, diag::note_constexpr_memcpy_unsupported)
9716 << Move << WChar << 0 << T << toString(OrigN, 10, /*Signed*/false)
9717 << (unsigned)TSize;
9718 return false;
9719 }
9720 }
9721
9722 // Check that the copying will remain within the arrays, just so that we
9723 // can give a more meaningful diagnostic. This implicitly also checks that
9724 // N fits into 64 bits.
9725 uint64_t RemainingSrcSize = Src.Designator.validIndexAdjustments().second;
9726 uint64_t RemainingDestSize = Dest.Designator.validIndexAdjustments().second;
9727 if (N.ugt(RemainingSrcSize) || N.ugt(RemainingDestSize)) {
9728 Info.FFDiag(E, diag::note_constexpr_memcpy_unsupported)
9729 << Move << WChar << (N.ugt(RemainingSrcSize) ? 1 : 2) << T
9730 << toString(N, 10, /*Signed*/false);
9731 return false;
9732 }
9733 uint64_t NElems = N.getZExtValue();
9734 uint64_t NBytes = NElems * TSize;
9735
9736 // Check for overlap.
9737 int Direction = 1;
9738 if (HasSameBase(Src, Dest)) {
9739 uint64_t SrcOffset = Src.getLValueOffset().getQuantity();
9740 uint64_t DestOffset = Dest.getLValueOffset().getQuantity();
9741 if (DestOffset >= SrcOffset && DestOffset - SrcOffset < NBytes) {
9742 // Dest is inside the source region.
9743 if (!Move) {
9744 Info.FFDiag(E, diag::note_constexpr_memcpy_overlap) << WChar;
9745 return false;
9746 }
9747 // For memmove and friends, copy backwards.
9748 if (!HandleLValueArrayAdjustment(Info, E, Src, T, NElems - 1) ||
9749 !HandleLValueArrayAdjustment(Info, E, Dest, T, NElems - 1))
9750 return false;
9751 Direction = -1;
9752 } else if (!Move && SrcOffset >= DestOffset &&
9753 SrcOffset - DestOffset < NBytes) {
9754 // Src is inside the destination region for memcpy: invalid.
9755 Info.FFDiag(E, diag::note_constexpr_memcpy_overlap) << WChar;
9756 return false;
9757 }
9758 }
9759
9760 while (true) {
9761 APValue Val;
9762 // FIXME: Set WantObjectRepresentation to true if we're copying a
9763 // char-like type?
9764 if (!handleLValueToRValueConversion(Info, E, T, Src, Val) ||
9765 !handleAssignment(Info, E, Dest, T, Val))
9766 return false;
9767 // Do not iterate past the last element; if we're copying backwards, that
9768 // might take us off the start of the array.
9769 if (--NElems == 0)
9770 return true;
9771 if (!HandleLValueArrayAdjustment(Info, E, Src, T, Direction) ||
9772 !HandleLValueArrayAdjustment(Info, E, Dest, T, Direction))
9773 return false;
9774 }
9775 }
9776
9777 default:
9778 return false;
9779 }
9780 }
9781
9782 static bool EvaluateArrayNewInitList(EvalInfo &Info, LValue &This,
9783 APValue &Result, const InitListExpr *ILE,
9784 QualType AllocType);
9785 static bool EvaluateArrayNewConstructExpr(EvalInfo &Info, LValue &This,
9786 APValue &Result,
9787 const CXXConstructExpr *CCE,
9788 QualType AllocType);
9789
VisitCXXNewExpr(const CXXNewExpr * E)9790 bool PointerExprEvaluator::VisitCXXNewExpr(const CXXNewExpr *E) {
9791 if (!Info.getLangOpts().CPlusPlus20)
9792 Info.CCEDiag(E, diag::note_constexpr_new);
9793
9794 // We cannot speculatively evaluate a delete expression.
9795 if (Info.SpeculativeEvaluationDepth)
9796 return false;
9797
9798 FunctionDecl *OperatorNew = E->getOperatorNew();
9799
9800 bool IsNothrow = false;
9801 bool IsPlacement = false;
9802 if (OperatorNew->isReservedGlobalPlacementOperator() &&
9803 Info.CurrentCall->isStdFunction() && !E->isArray()) {
9804 // FIXME Support array placement new.
9805 assert(E->getNumPlacementArgs() == 1);
9806 if (!EvaluatePointer(E->getPlacementArg(0), Result, Info))
9807 return false;
9808 if (Result.Designator.Invalid)
9809 return false;
9810 IsPlacement = true;
9811 } else if (!OperatorNew->isReplaceableGlobalAllocationFunction()) {
9812 Info.FFDiag(E, diag::note_constexpr_new_non_replaceable)
9813 << isa<CXXMethodDecl>(OperatorNew) << OperatorNew;
9814 return false;
9815 } else if (E->getNumPlacementArgs()) {
9816 // The only new-placement list we support is of the form (std::nothrow).
9817 //
9818 // FIXME: There is no restriction on this, but it's not clear that any
9819 // other form makes any sense. We get here for cases such as:
9820 //
9821 // new (std::align_val_t{N}) X(int)
9822 //
9823 // (which should presumably be valid only if N is a multiple of
9824 // alignof(int), and in any case can't be deallocated unless N is
9825 // alignof(X) and X has new-extended alignment).
9826 if (E->getNumPlacementArgs() != 1 ||
9827 !E->getPlacementArg(0)->getType()->isNothrowT())
9828 return Error(E, diag::note_constexpr_new_placement);
9829
9830 LValue Nothrow;
9831 if (!EvaluateLValue(E->getPlacementArg(0), Nothrow, Info))
9832 return false;
9833 IsNothrow = true;
9834 }
9835
9836 const Expr *Init = E->getInitializer();
9837 const InitListExpr *ResizedArrayILE = nullptr;
9838 const CXXConstructExpr *ResizedArrayCCE = nullptr;
9839 bool ValueInit = false;
9840
9841 QualType AllocType = E->getAllocatedType();
9842 if (std::optional<const Expr *> ArraySize = E->getArraySize()) {
9843 const Expr *Stripped = *ArraySize;
9844 for (; auto *ICE = dyn_cast<ImplicitCastExpr>(Stripped);
9845 Stripped = ICE->getSubExpr())
9846 if (ICE->getCastKind() != CK_NoOp &&
9847 ICE->getCastKind() != CK_IntegralCast)
9848 break;
9849
9850 llvm::APSInt ArrayBound;
9851 if (!EvaluateInteger(Stripped, ArrayBound, Info))
9852 return false;
9853
9854 // C++ [expr.new]p9:
9855 // The expression is erroneous if:
9856 // -- [...] its value before converting to size_t [or] applying the
9857 // second standard conversion sequence is less than zero
9858 if (ArrayBound.isSigned() && ArrayBound.isNegative()) {
9859 if (IsNothrow)
9860 return ZeroInitialization(E);
9861
9862 Info.FFDiag(*ArraySize, diag::note_constexpr_new_negative)
9863 << ArrayBound << (*ArraySize)->getSourceRange();
9864 return false;
9865 }
9866
9867 // -- its value is such that the size of the allocated object would
9868 // exceed the implementation-defined limit
9869 if (!Info.CheckArraySize(ArraySize.value()->getExprLoc(),
9870 ConstantArrayType::getNumAddressingBits(
9871 Info.Ctx, AllocType, ArrayBound),
9872 ArrayBound.getZExtValue(), /*Diag=*/!IsNothrow)) {
9873 if (IsNothrow)
9874 return ZeroInitialization(E);
9875 return false;
9876 }
9877
9878 // -- the new-initializer is a braced-init-list and the number of
9879 // array elements for which initializers are provided [...]
9880 // exceeds the number of elements to initialize
9881 if (!Init) {
9882 // No initialization is performed.
9883 } else if (isa<CXXScalarValueInitExpr>(Init) ||
9884 isa<ImplicitValueInitExpr>(Init)) {
9885 ValueInit = true;
9886 } else if (auto *CCE = dyn_cast<CXXConstructExpr>(Init)) {
9887 ResizedArrayCCE = CCE;
9888 } else {
9889 auto *CAT = Info.Ctx.getAsConstantArrayType(Init->getType());
9890 assert(CAT && "unexpected type for array initializer");
9891
9892 unsigned Bits =
9893 std::max(CAT->getSize().getBitWidth(), ArrayBound.getBitWidth());
9894 llvm::APInt InitBound = CAT->getSize().zext(Bits);
9895 llvm::APInt AllocBound = ArrayBound.zext(Bits);
9896 if (InitBound.ugt(AllocBound)) {
9897 if (IsNothrow)
9898 return ZeroInitialization(E);
9899
9900 Info.FFDiag(*ArraySize, diag::note_constexpr_new_too_small)
9901 << toString(AllocBound, 10, /*Signed=*/false)
9902 << toString(InitBound, 10, /*Signed=*/false)
9903 << (*ArraySize)->getSourceRange();
9904 return false;
9905 }
9906
9907 // If the sizes differ, we must have an initializer list, and we need
9908 // special handling for this case when we initialize.
9909 if (InitBound != AllocBound)
9910 ResizedArrayILE = cast<InitListExpr>(Init);
9911 }
9912
9913 AllocType = Info.Ctx.getConstantArrayType(AllocType, ArrayBound, nullptr,
9914 ArraySizeModifier::Normal, 0);
9915 } else {
9916 assert(!AllocType->isArrayType() &&
9917 "array allocation with non-array new");
9918 }
9919
9920 APValue *Val;
9921 if (IsPlacement) {
9922 AccessKinds AK = AK_Construct;
9923 struct FindObjectHandler {
9924 EvalInfo &Info;
9925 const Expr *E;
9926 QualType AllocType;
9927 const AccessKinds AccessKind;
9928 APValue *Value;
9929
9930 typedef bool result_type;
9931 bool failed() { return false; }
9932 bool found(APValue &Subobj, QualType SubobjType) {
9933 // FIXME: Reject the cases where [basic.life]p8 would not permit the
9934 // old name of the object to be used to name the new object.
9935 if (!Info.Ctx.hasSameUnqualifiedType(SubobjType, AllocType)) {
9936 Info.FFDiag(E, diag::note_constexpr_placement_new_wrong_type) <<
9937 SubobjType << AllocType;
9938 return false;
9939 }
9940 Value = &Subobj;
9941 return true;
9942 }
9943 bool found(APSInt &Value, QualType SubobjType) {
9944 Info.FFDiag(E, diag::note_constexpr_construct_complex_elem);
9945 return false;
9946 }
9947 bool found(APFloat &Value, QualType SubobjType) {
9948 Info.FFDiag(E, diag::note_constexpr_construct_complex_elem);
9949 return false;
9950 }
9951 } Handler = {Info, E, AllocType, AK, nullptr};
9952
9953 CompleteObject Obj = findCompleteObject(Info, E, AK, Result, AllocType);
9954 if (!Obj || !findSubobject(Info, E, Obj, Result.Designator, Handler))
9955 return false;
9956
9957 Val = Handler.Value;
9958
9959 // [basic.life]p1:
9960 // The lifetime of an object o of type T ends when [...] the storage
9961 // which the object occupies is [...] reused by an object that is not
9962 // nested within o (6.6.2).
9963 *Val = APValue();
9964 } else {
9965 // Perform the allocation and obtain a pointer to the resulting object.
9966 Val = Info.createHeapAlloc(E, AllocType, Result);
9967 if (!Val)
9968 return false;
9969 }
9970
9971 if (ValueInit) {
9972 ImplicitValueInitExpr VIE(AllocType);
9973 if (!EvaluateInPlace(*Val, Info, Result, &VIE))
9974 return false;
9975 } else if (ResizedArrayILE) {
9976 if (!EvaluateArrayNewInitList(Info, Result, *Val, ResizedArrayILE,
9977 AllocType))
9978 return false;
9979 } else if (ResizedArrayCCE) {
9980 if (!EvaluateArrayNewConstructExpr(Info, Result, *Val, ResizedArrayCCE,
9981 AllocType))
9982 return false;
9983 } else if (Init) {
9984 if (!EvaluateInPlace(*Val, Info, Result, Init))
9985 return false;
9986 } else if (!handleDefaultInitValue(AllocType, *Val)) {
9987 return false;
9988 }
9989
9990 // Array new returns a pointer to the first element, not a pointer to the
9991 // array.
9992 if (auto *AT = AllocType->getAsArrayTypeUnsafe())
9993 Result.addArray(Info, E, cast<ConstantArrayType>(AT));
9994
9995 return true;
9996 }
9997 //===----------------------------------------------------------------------===//
9998 // Member Pointer Evaluation
9999 //===----------------------------------------------------------------------===//
10000
10001 namespace {
10002 class MemberPointerExprEvaluator
10003 : public ExprEvaluatorBase<MemberPointerExprEvaluator> {
10004 MemberPtr &Result;
10005
Success(const ValueDecl * D)10006 bool Success(const ValueDecl *D) {
10007 Result = MemberPtr(D);
10008 return true;
10009 }
10010 public:
10011
MemberPointerExprEvaluator(EvalInfo & Info,MemberPtr & Result)10012 MemberPointerExprEvaluator(EvalInfo &Info, MemberPtr &Result)
10013 : ExprEvaluatorBaseTy(Info), Result(Result) {}
10014
Success(const APValue & V,const Expr * E)10015 bool Success(const APValue &V, const Expr *E) {
10016 Result.setFrom(V);
10017 return true;
10018 }
ZeroInitialization(const Expr * E)10019 bool ZeroInitialization(const Expr *E) {
10020 return Success((const ValueDecl*)nullptr);
10021 }
10022
10023 bool VisitCastExpr(const CastExpr *E);
10024 bool VisitUnaryAddrOf(const UnaryOperator *E);
10025 };
10026 } // end anonymous namespace
10027
EvaluateMemberPointer(const Expr * E,MemberPtr & Result,EvalInfo & Info)10028 static bool EvaluateMemberPointer(const Expr *E, MemberPtr &Result,
10029 EvalInfo &Info) {
10030 assert(!E->isValueDependent());
10031 assert(E->isPRValue() && E->getType()->isMemberPointerType());
10032 return MemberPointerExprEvaluator(Info, Result).Visit(E);
10033 }
10034
VisitCastExpr(const CastExpr * E)10035 bool MemberPointerExprEvaluator::VisitCastExpr(const CastExpr *E) {
10036 switch (E->getCastKind()) {
10037 default:
10038 return ExprEvaluatorBaseTy::VisitCastExpr(E);
10039
10040 case CK_NullToMemberPointer:
10041 VisitIgnoredValue(E->getSubExpr());
10042 return ZeroInitialization(E);
10043
10044 case CK_BaseToDerivedMemberPointer: {
10045 if (!Visit(E->getSubExpr()))
10046 return false;
10047 if (E->path_empty())
10048 return true;
10049 // Base-to-derived member pointer casts store the path in derived-to-base
10050 // order, so iterate backwards. The CXXBaseSpecifier also provides us with
10051 // the wrong end of the derived->base arc, so stagger the path by one class.
10052 typedef std::reverse_iterator<CastExpr::path_const_iterator> ReverseIter;
10053 for (ReverseIter PathI(E->path_end() - 1), PathE(E->path_begin());
10054 PathI != PathE; ++PathI) {
10055 assert(!(*PathI)->isVirtual() && "memptr cast through vbase");
10056 const CXXRecordDecl *Derived = (*PathI)->getType()->getAsCXXRecordDecl();
10057 if (!Result.castToDerived(Derived))
10058 return Error(E);
10059 }
10060 const Type *FinalTy = E->getType()->castAs<MemberPointerType>()->getClass();
10061 if (!Result.castToDerived(FinalTy->getAsCXXRecordDecl()))
10062 return Error(E);
10063 return true;
10064 }
10065
10066 case CK_DerivedToBaseMemberPointer:
10067 if (!Visit(E->getSubExpr()))
10068 return false;
10069 for (CastExpr::path_const_iterator PathI = E->path_begin(),
10070 PathE = E->path_end(); PathI != PathE; ++PathI) {
10071 assert(!(*PathI)->isVirtual() && "memptr cast through vbase");
10072 const CXXRecordDecl *Base = (*PathI)->getType()->getAsCXXRecordDecl();
10073 if (!Result.castToBase(Base))
10074 return Error(E);
10075 }
10076 return true;
10077 }
10078 }
10079
VisitUnaryAddrOf(const UnaryOperator * E)10080 bool MemberPointerExprEvaluator::VisitUnaryAddrOf(const UnaryOperator *E) {
10081 // C++11 [expr.unary.op]p3 has very strict rules on how the address of a
10082 // member can be formed.
10083 return Success(cast<DeclRefExpr>(E->getSubExpr())->getDecl());
10084 }
10085
10086 //===----------------------------------------------------------------------===//
10087 // Record Evaluation
10088 //===----------------------------------------------------------------------===//
10089
10090 namespace {
10091 class RecordExprEvaluator
10092 : public ExprEvaluatorBase<RecordExprEvaluator> {
10093 const LValue &This;
10094 APValue &Result;
10095 public:
10096
RecordExprEvaluator(EvalInfo & info,const LValue & This,APValue & Result)10097 RecordExprEvaluator(EvalInfo &info, const LValue &This, APValue &Result)
10098 : ExprEvaluatorBaseTy(info), This(This), Result(Result) {}
10099
Success(const APValue & V,const Expr * E)10100 bool Success(const APValue &V, const Expr *E) {
10101 Result = V;
10102 return true;
10103 }
ZeroInitialization(const Expr * E)10104 bool ZeroInitialization(const Expr *E) {
10105 return ZeroInitialization(E, E->getType());
10106 }
10107 bool ZeroInitialization(const Expr *E, QualType T);
10108
VisitCallExpr(const CallExpr * E)10109 bool VisitCallExpr(const CallExpr *E) {
10110 return handleCallExpr(E, Result, &This);
10111 }
10112 bool VisitCastExpr(const CastExpr *E);
10113 bool VisitInitListExpr(const InitListExpr *E);
VisitCXXConstructExpr(const CXXConstructExpr * E)10114 bool VisitCXXConstructExpr(const CXXConstructExpr *E) {
10115 return VisitCXXConstructExpr(E, E->getType());
10116 }
10117 bool VisitLambdaExpr(const LambdaExpr *E);
10118 bool VisitCXXInheritedCtorInitExpr(const CXXInheritedCtorInitExpr *E);
10119 bool VisitCXXConstructExpr(const CXXConstructExpr *E, QualType T);
10120 bool VisitCXXStdInitializerListExpr(const CXXStdInitializerListExpr *E);
10121 bool VisitBinCmp(const BinaryOperator *E);
10122 bool VisitCXXParenListInitExpr(const CXXParenListInitExpr *E);
10123 bool VisitCXXParenListOrInitListExpr(const Expr *ExprToVisit,
10124 ArrayRef<Expr *> Args);
10125 };
10126 }
10127
10128 /// Perform zero-initialization on an object of non-union class type.
10129 /// C++11 [dcl.init]p5:
10130 /// To zero-initialize an object or reference of type T means:
10131 /// [...]
10132 /// -- if T is a (possibly cv-qualified) non-union class type,
10133 /// each non-static data member and each base-class subobject is
10134 /// zero-initialized
HandleClassZeroInitialization(EvalInfo & Info,const Expr * E,const RecordDecl * RD,const LValue & This,APValue & Result)10135 static bool HandleClassZeroInitialization(EvalInfo &Info, const Expr *E,
10136 const RecordDecl *RD,
10137 const LValue &This, APValue &Result) {
10138 assert(!RD->isUnion() && "Expected non-union class type");
10139 const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(RD);
10140 Result = APValue(APValue::UninitStruct(), CD ? CD->getNumBases() : 0,
10141 std::distance(RD->field_begin(), RD->field_end()));
10142
10143 if (RD->isInvalidDecl()) return false;
10144 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
10145
10146 if (CD) {
10147 unsigned Index = 0;
10148 for (CXXRecordDecl::base_class_const_iterator I = CD->bases_begin(),
10149 End = CD->bases_end(); I != End; ++I, ++Index) {
10150 const CXXRecordDecl *Base = I->getType()->getAsCXXRecordDecl();
10151 LValue Subobject = This;
10152 if (!HandleLValueDirectBase(Info, E, Subobject, CD, Base, &Layout))
10153 return false;
10154 if (!HandleClassZeroInitialization(Info, E, Base, Subobject,
10155 Result.getStructBase(Index)))
10156 return false;
10157 }
10158 }
10159
10160 for (const auto *I : RD->fields()) {
10161 // -- if T is a reference type, no initialization is performed.
10162 if (I->isUnnamedBitfield() || I->getType()->isReferenceType())
10163 continue;
10164
10165 LValue Subobject = This;
10166 if (!HandleLValueMember(Info, E, Subobject, I, &Layout))
10167 return false;
10168
10169 ImplicitValueInitExpr VIE(I->getType());
10170 if (!EvaluateInPlace(
10171 Result.getStructField(I->getFieldIndex()), Info, Subobject, &VIE))
10172 return false;
10173 }
10174
10175 return true;
10176 }
10177
ZeroInitialization(const Expr * E,QualType T)10178 bool RecordExprEvaluator::ZeroInitialization(const Expr *E, QualType T) {
10179 const RecordDecl *RD = T->castAs<RecordType>()->getDecl();
10180 if (RD->isInvalidDecl()) return false;
10181 if (RD->isUnion()) {
10182 // C++11 [dcl.init]p5: If T is a (possibly cv-qualified) union type, the
10183 // object's first non-static named data member is zero-initialized
10184 RecordDecl::field_iterator I = RD->field_begin();
10185 while (I != RD->field_end() && (*I)->isUnnamedBitfield())
10186 ++I;
10187 if (I == RD->field_end()) {
10188 Result = APValue((const FieldDecl*)nullptr);
10189 return true;
10190 }
10191
10192 LValue Subobject = This;
10193 if (!HandleLValueMember(Info, E, Subobject, *I))
10194 return false;
10195 Result = APValue(*I);
10196 ImplicitValueInitExpr VIE(I->getType());
10197 return EvaluateInPlace(Result.getUnionValue(), Info, Subobject, &VIE);
10198 }
10199
10200 if (isa<CXXRecordDecl>(RD) && cast<CXXRecordDecl>(RD)->getNumVBases()) {
10201 Info.FFDiag(E, diag::note_constexpr_virtual_base) << RD;
10202 return false;
10203 }
10204
10205 return HandleClassZeroInitialization(Info, E, RD, This, Result);
10206 }
10207
VisitCastExpr(const CastExpr * E)10208 bool RecordExprEvaluator::VisitCastExpr(const CastExpr *E) {
10209 switch (E->getCastKind()) {
10210 default:
10211 return ExprEvaluatorBaseTy::VisitCastExpr(E);
10212
10213 case CK_ConstructorConversion:
10214 return Visit(E->getSubExpr());
10215
10216 case CK_DerivedToBase:
10217 case CK_UncheckedDerivedToBase: {
10218 APValue DerivedObject;
10219 if (!Evaluate(DerivedObject, Info, E->getSubExpr()))
10220 return false;
10221 if (!DerivedObject.isStruct())
10222 return Error(E->getSubExpr());
10223
10224 // Derived-to-base rvalue conversion: just slice off the derived part.
10225 APValue *Value = &DerivedObject;
10226 const CXXRecordDecl *RD = E->getSubExpr()->getType()->getAsCXXRecordDecl();
10227 for (CastExpr::path_const_iterator PathI = E->path_begin(),
10228 PathE = E->path_end(); PathI != PathE; ++PathI) {
10229 assert(!(*PathI)->isVirtual() && "record rvalue with virtual base");
10230 const CXXRecordDecl *Base = (*PathI)->getType()->getAsCXXRecordDecl();
10231 Value = &Value->getStructBase(getBaseIndex(RD, Base));
10232 RD = Base;
10233 }
10234 Result = *Value;
10235 return true;
10236 }
10237 }
10238 }
10239
VisitInitListExpr(const InitListExpr * E)10240 bool RecordExprEvaluator::VisitInitListExpr(const InitListExpr *E) {
10241 if (E->isTransparent())
10242 return Visit(E->getInit(0));
10243 return VisitCXXParenListOrInitListExpr(E, E->inits());
10244 }
10245
VisitCXXParenListOrInitListExpr(const Expr * ExprToVisit,ArrayRef<Expr * > Args)10246 bool RecordExprEvaluator::VisitCXXParenListOrInitListExpr(
10247 const Expr *ExprToVisit, ArrayRef<Expr *> Args) {
10248 const RecordDecl *RD =
10249 ExprToVisit->getType()->castAs<RecordType>()->getDecl();
10250 if (RD->isInvalidDecl()) return false;
10251 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
10252 auto *CXXRD = dyn_cast<CXXRecordDecl>(RD);
10253
10254 EvalInfo::EvaluatingConstructorRAII EvalObj(
10255 Info,
10256 ObjectUnderConstruction{This.getLValueBase(), This.Designator.Entries},
10257 CXXRD && CXXRD->getNumBases());
10258
10259 if (RD->isUnion()) {
10260 const FieldDecl *Field;
10261 if (auto *ILE = dyn_cast<InitListExpr>(ExprToVisit)) {
10262 Field = ILE->getInitializedFieldInUnion();
10263 } else if (auto *PLIE = dyn_cast<CXXParenListInitExpr>(ExprToVisit)) {
10264 Field = PLIE->getInitializedFieldInUnion();
10265 } else {
10266 llvm_unreachable(
10267 "Expression is neither an init list nor a C++ paren list");
10268 }
10269
10270 Result = APValue(Field);
10271 if (!Field)
10272 return true;
10273
10274 // If the initializer list for a union does not contain any elements, the
10275 // first element of the union is value-initialized.
10276 // FIXME: The element should be initialized from an initializer list.
10277 // Is this difference ever observable for initializer lists which
10278 // we don't build?
10279 ImplicitValueInitExpr VIE(Field->getType());
10280 const Expr *InitExpr = Args.empty() ? &VIE : Args[0];
10281
10282 LValue Subobject = This;
10283 if (!HandleLValueMember(Info, InitExpr, Subobject, Field, &Layout))
10284 return false;
10285
10286 // Temporarily override This, in case there's a CXXDefaultInitExpr in here.
10287 ThisOverrideRAII ThisOverride(*Info.CurrentCall, &This,
10288 isa<CXXDefaultInitExpr>(InitExpr));
10289
10290 if (EvaluateInPlace(Result.getUnionValue(), Info, Subobject, InitExpr)) {
10291 if (Field->isBitField())
10292 return truncateBitfieldValue(Info, InitExpr, Result.getUnionValue(),
10293 Field);
10294 return true;
10295 }
10296
10297 return false;
10298 }
10299
10300 if (!Result.hasValue())
10301 Result = APValue(APValue::UninitStruct(), CXXRD ? CXXRD->getNumBases() : 0,
10302 std::distance(RD->field_begin(), RD->field_end()));
10303 unsigned ElementNo = 0;
10304 bool Success = true;
10305
10306 // Initialize base classes.
10307 if (CXXRD && CXXRD->getNumBases()) {
10308 for (const auto &Base : CXXRD->bases()) {
10309 assert(ElementNo < Args.size() && "missing init for base class");
10310 const Expr *Init = Args[ElementNo];
10311
10312 LValue Subobject = This;
10313 if (!HandleLValueBase(Info, Init, Subobject, CXXRD, &Base))
10314 return false;
10315
10316 APValue &FieldVal = Result.getStructBase(ElementNo);
10317 if (!EvaluateInPlace(FieldVal, Info, Subobject, Init)) {
10318 if (!Info.noteFailure())
10319 return false;
10320 Success = false;
10321 }
10322 ++ElementNo;
10323 }
10324
10325 EvalObj.finishedConstructingBases();
10326 }
10327
10328 // Initialize members.
10329 for (const auto *Field : RD->fields()) {
10330 // Anonymous bit-fields are not considered members of the class for
10331 // purposes of aggregate initialization.
10332 if (Field->isUnnamedBitfield())
10333 continue;
10334
10335 LValue Subobject = This;
10336
10337 bool HaveInit = ElementNo < Args.size();
10338
10339 // FIXME: Diagnostics here should point to the end of the initializer
10340 // list, not the start.
10341 if (!HandleLValueMember(Info, HaveInit ? Args[ElementNo] : ExprToVisit,
10342 Subobject, Field, &Layout))
10343 return false;
10344
10345 // Perform an implicit value-initialization for members beyond the end of
10346 // the initializer list.
10347 ImplicitValueInitExpr VIE(HaveInit ? Info.Ctx.IntTy : Field->getType());
10348 const Expr *Init = HaveInit ? Args[ElementNo++] : &VIE;
10349
10350 if (Field->getType()->isIncompleteArrayType()) {
10351 if (auto *CAT = Info.Ctx.getAsConstantArrayType(Init->getType())) {
10352 if (!CAT->getSize().isZero()) {
10353 // Bail out for now. This might sort of "work", but the rest of the
10354 // code isn't really prepared to handle it.
10355 Info.FFDiag(Init, diag::note_constexpr_unsupported_flexible_array);
10356 return false;
10357 }
10358 }
10359 }
10360
10361 // Temporarily override This, in case there's a CXXDefaultInitExpr in here.
10362 ThisOverrideRAII ThisOverride(*Info.CurrentCall, &This,
10363 isa<CXXDefaultInitExpr>(Init));
10364
10365 APValue &FieldVal = Result.getStructField(Field->getFieldIndex());
10366 if (!EvaluateInPlace(FieldVal, Info, Subobject, Init) ||
10367 (Field->isBitField() && !truncateBitfieldValue(Info, Init,
10368 FieldVal, Field))) {
10369 if (!Info.noteFailure())
10370 return false;
10371 Success = false;
10372 }
10373 }
10374
10375 EvalObj.finishedConstructingFields();
10376
10377 return Success;
10378 }
10379
VisitCXXConstructExpr(const CXXConstructExpr * E,QualType T)10380 bool RecordExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E,
10381 QualType T) {
10382 // Note that E's type is not necessarily the type of our class here; we might
10383 // be initializing an array element instead.
10384 const CXXConstructorDecl *FD = E->getConstructor();
10385 if (FD->isInvalidDecl() || FD->getParent()->isInvalidDecl()) return false;
10386
10387 bool ZeroInit = E->requiresZeroInitialization();
10388 if (CheckTrivialDefaultConstructor(Info, E->getExprLoc(), FD, ZeroInit)) {
10389 // If we've already performed zero-initialization, we're already done.
10390 if (Result.hasValue())
10391 return true;
10392
10393 if (ZeroInit)
10394 return ZeroInitialization(E, T);
10395
10396 return handleDefaultInitValue(T, Result);
10397 }
10398
10399 const FunctionDecl *Definition = nullptr;
10400 auto Body = FD->getBody(Definition);
10401
10402 if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition, Body))
10403 return false;
10404
10405 // Avoid materializing a temporary for an elidable copy/move constructor.
10406 if (E->isElidable() && !ZeroInit) {
10407 // FIXME: This only handles the simplest case, where the source object
10408 // is passed directly as the first argument to the constructor.
10409 // This should also handle stepping though implicit casts and
10410 // and conversion sequences which involve two steps, with a
10411 // conversion operator followed by a converting constructor.
10412 const Expr *SrcObj = E->getArg(0);
10413 assert(SrcObj->isTemporaryObject(Info.Ctx, FD->getParent()));
10414 assert(Info.Ctx.hasSameUnqualifiedType(E->getType(), SrcObj->getType()));
10415 if (const MaterializeTemporaryExpr *ME =
10416 dyn_cast<MaterializeTemporaryExpr>(SrcObj))
10417 return Visit(ME->getSubExpr());
10418 }
10419
10420 if (ZeroInit && !ZeroInitialization(E, T))
10421 return false;
10422
10423 auto Args = llvm::ArrayRef(E->getArgs(), E->getNumArgs());
10424 return HandleConstructorCall(E, This, Args,
10425 cast<CXXConstructorDecl>(Definition), Info,
10426 Result);
10427 }
10428
VisitCXXInheritedCtorInitExpr(const CXXInheritedCtorInitExpr * E)10429 bool RecordExprEvaluator::VisitCXXInheritedCtorInitExpr(
10430 const CXXInheritedCtorInitExpr *E) {
10431 if (!Info.CurrentCall) {
10432 assert(Info.checkingPotentialConstantExpression());
10433 return false;
10434 }
10435
10436 const CXXConstructorDecl *FD = E->getConstructor();
10437 if (FD->isInvalidDecl() || FD->getParent()->isInvalidDecl())
10438 return false;
10439
10440 const FunctionDecl *Definition = nullptr;
10441 auto Body = FD->getBody(Definition);
10442
10443 if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition, Body))
10444 return false;
10445
10446 return HandleConstructorCall(E, This, Info.CurrentCall->Arguments,
10447 cast<CXXConstructorDecl>(Definition), Info,
10448 Result);
10449 }
10450
VisitCXXStdInitializerListExpr(const CXXStdInitializerListExpr * E)10451 bool RecordExprEvaluator::VisitCXXStdInitializerListExpr(
10452 const CXXStdInitializerListExpr *E) {
10453 const ConstantArrayType *ArrayType =
10454 Info.Ctx.getAsConstantArrayType(E->getSubExpr()->getType());
10455
10456 LValue Array;
10457 if (!EvaluateLValue(E->getSubExpr(), Array, Info))
10458 return false;
10459
10460 assert(ArrayType && "unexpected type for array initializer");
10461
10462 // Get a pointer to the first element of the array.
10463 Array.addArray(Info, E, ArrayType);
10464
10465 auto InvalidType = [&] {
10466 Info.FFDiag(E, diag::note_constexpr_unsupported_layout)
10467 << E->getType();
10468 return false;
10469 };
10470
10471 // FIXME: Perform the checks on the field types in SemaInit.
10472 RecordDecl *Record = E->getType()->castAs<RecordType>()->getDecl();
10473 RecordDecl::field_iterator Field = Record->field_begin();
10474 if (Field == Record->field_end())
10475 return InvalidType();
10476
10477 // Start pointer.
10478 if (!Field->getType()->isPointerType() ||
10479 !Info.Ctx.hasSameType(Field->getType()->getPointeeType(),
10480 ArrayType->getElementType()))
10481 return InvalidType();
10482
10483 // FIXME: What if the initializer_list type has base classes, etc?
10484 Result = APValue(APValue::UninitStruct(), 0, 2);
10485 Array.moveInto(Result.getStructField(0));
10486
10487 if (++Field == Record->field_end())
10488 return InvalidType();
10489
10490 if (Field->getType()->isPointerType() &&
10491 Info.Ctx.hasSameType(Field->getType()->getPointeeType(),
10492 ArrayType->getElementType())) {
10493 // End pointer.
10494 if (!HandleLValueArrayAdjustment(Info, E, Array,
10495 ArrayType->getElementType(),
10496 ArrayType->getSize().getZExtValue()))
10497 return false;
10498 Array.moveInto(Result.getStructField(1));
10499 } else if (Info.Ctx.hasSameType(Field->getType(), Info.Ctx.getSizeType()))
10500 // Length.
10501 Result.getStructField(1) = APValue(APSInt(ArrayType->getSize()));
10502 else
10503 return InvalidType();
10504
10505 if (++Field != Record->field_end())
10506 return InvalidType();
10507
10508 return true;
10509 }
10510
VisitLambdaExpr(const LambdaExpr * E)10511 bool RecordExprEvaluator::VisitLambdaExpr(const LambdaExpr *E) {
10512 const CXXRecordDecl *ClosureClass = E->getLambdaClass();
10513 if (ClosureClass->isInvalidDecl())
10514 return false;
10515
10516 const size_t NumFields =
10517 std::distance(ClosureClass->field_begin(), ClosureClass->field_end());
10518
10519 assert(NumFields == (size_t)std::distance(E->capture_init_begin(),
10520 E->capture_init_end()) &&
10521 "The number of lambda capture initializers should equal the number of "
10522 "fields within the closure type");
10523
10524 Result = APValue(APValue::UninitStruct(), /*NumBases*/0, NumFields);
10525 // Iterate through all the lambda's closure object's fields and initialize
10526 // them.
10527 auto *CaptureInitIt = E->capture_init_begin();
10528 bool Success = true;
10529 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(ClosureClass);
10530 for (const auto *Field : ClosureClass->fields()) {
10531 assert(CaptureInitIt != E->capture_init_end());
10532 // Get the initializer for this field
10533 Expr *const CurFieldInit = *CaptureInitIt++;
10534
10535 // If there is no initializer, either this is a VLA or an error has
10536 // occurred.
10537 if (!CurFieldInit)
10538 return Error(E);
10539
10540 LValue Subobject = This;
10541
10542 if (!HandleLValueMember(Info, E, Subobject, Field, &Layout))
10543 return false;
10544
10545 APValue &FieldVal = Result.getStructField(Field->getFieldIndex());
10546 if (!EvaluateInPlace(FieldVal, Info, Subobject, CurFieldInit)) {
10547 if (!Info.keepEvaluatingAfterFailure())
10548 return false;
10549 Success = false;
10550 }
10551 }
10552 return Success;
10553 }
10554
EvaluateRecord(const Expr * E,const LValue & This,APValue & Result,EvalInfo & Info)10555 static bool EvaluateRecord(const Expr *E, const LValue &This,
10556 APValue &Result, EvalInfo &Info) {
10557 assert(!E->isValueDependent());
10558 assert(E->isPRValue() && E->getType()->isRecordType() &&
10559 "can't evaluate expression as a record rvalue");
10560 return RecordExprEvaluator(Info, This, Result).Visit(E);
10561 }
10562
10563 //===----------------------------------------------------------------------===//
10564 // Temporary Evaluation
10565 //
10566 // Temporaries are represented in the AST as rvalues, but generally behave like
10567 // lvalues. The full-object of which the temporary is a subobject is implicitly
10568 // materialized so that a reference can bind to it.
10569 //===----------------------------------------------------------------------===//
10570 namespace {
10571 class TemporaryExprEvaluator
10572 : public LValueExprEvaluatorBase<TemporaryExprEvaluator> {
10573 public:
TemporaryExprEvaluator(EvalInfo & Info,LValue & Result)10574 TemporaryExprEvaluator(EvalInfo &Info, LValue &Result) :
10575 LValueExprEvaluatorBaseTy(Info, Result, false) {}
10576
10577 /// Visit an expression which constructs the value of this temporary.
VisitConstructExpr(const Expr * E)10578 bool VisitConstructExpr(const Expr *E) {
10579 APValue &Value = Info.CurrentCall->createTemporary(
10580 E, E->getType(), ScopeKind::FullExpression, Result);
10581 return EvaluateInPlace(Value, Info, Result, E);
10582 }
10583
VisitCastExpr(const CastExpr * E)10584 bool VisitCastExpr(const CastExpr *E) {
10585 switch (E->getCastKind()) {
10586 default:
10587 return LValueExprEvaluatorBaseTy::VisitCastExpr(E);
10588
10589 case CK_ConstructorConversion:
10590 return VisitConstructExpr(E->getSubExpr());
10591 }
10592 }
VisitInitListExpr(const InitListExpr * E)10593 bool VisitInitListExpr(const InitListExpr *E) {
10594 return VisitConstructExpr(E);
10595 }
VisitCXXConstructExpr(const CXXConstructExpr * E)10596 bool VisitCXXConstructExpr(const CXXConstructExpr *E) {
10597 return VisitConstructExpr(E);
10598 }
VisitCallExpr(const CallExpr * E)10599 bool VisitCallExpr(const CallExpr *E) {
10600 return VisitConstructExpr(E);
10601 }
VisitCXXStdInitializerListExpr(const CXXStdInitializerListExpr * E)10602 bool VisitCXXStdInitializerListExpr(const CXXStdInitializerListExpr *E) {
10603 return VisitConstructExpr(E);
10604 }
VisitLambdaExpr(const LambdaExpr * E)10605 bool VisitLambdaExpr(const LambdaExpr *E) {
10606 return VisitConstructExpr(E);
10607 }
10608 };
10609 } // end anonymous namespace
10610
10611 /// Evaluate an expression of record type as a temporary.
EvaluateTemporary(const Expr * E,LValue & Result,EvalInfo & Info)10612 static bool EvaluateTemporary(const Expr *E, LValue &Result, EvalInfo &Info) {
10613 assert(!E->isValueDependent());
10614 assert(E->isPRValue() && E->getType()->isRecordType());
10615 return TemporaryExprEvaluator(Info, Result).Visit(E);
10616 }
10617
10618 //===----------------------------------------------------------------------===//
10619 // Vector Evaluation
10620 //===----------------------------------------------------------------------===//
10621
10622 namespace {
10623 class VectorExprEvaluator
10624 : public ExprEvaluatorBase<VectorExprEvaluator> {
10625 APValue &Result;
10626 public:
10627
VectorExprEvaluator(EvalInfo & info,APValue & Result)10628 VectorExprEvaluator(EvalInfo &info, APValue &Result)
10629 : ExprEvaluatorBaseTy(info), Result(Result) {}
10630
Success(ArrayRef<APValue> V,const Expr * E)10631 bool Success(ArrayRef<APValue> V, const Expr *E) {
10632 assert(V.size() == E->getType()->castAs<VectorType>()->getNumElements());
10633 // FIXME: remove this APValue copy.
10634 Result = APValue(V.data(), V.size());
10635 return true;
10636 }
Success(const APValue & V,const Expr * E)10637 bool Success(const APValue &V, const Expr *E) {
10638 assert(V.isVector());
10639 Result = V;
10640 return true;
10641 }
10642 bool ZeroInitialization(const Expr *E);
10643
VisitUnaryReal(const UnaryOperator * E)10644 bool VisitUnaryReal(const UnaryOperator *E)
10645 { return Visit(E->getSubExpr()); }
10646 bool VisitCastExpr(const CastExpr* E);
10647 bool VisitInitListExpr(const InitListExpr *E);
10648 bool VisitUnaryImag(const UnaryOperator *E);
10649 bool VisitBinaryOperator(const BinaryOperator *E);
10650 bool VisitUnaryOperator(const UnaryOperator *E);
10651 // FIXME: Missing: conditional operator (for GNU
10652 // conditional select), shufflevector, ExtVectorElementExpr
10653 };
10654 } // end anonymous namespace
10655
EvaluateVector(const Expr * E,APValue & Result,EvalInfo & Info)10656 static bool EvaluateVector(const Expr* E, APValue& Result, EvalInfo &Info) {
10657 assert(E->isPRValue() && E->getType()->isVectorType() &&
10658 "not a vector prvalue");
10659 return VectorExprEvaluator(Info, Result).Visit(E);
10660 }
10661
VisitCastExpr(const CastExpr * E)10662 bool VectorExprEvaluator::VisitCastExpr(const CastExpr *E) {
10663 const VectorType *VTy = E->getType()->castAs<VectorType>();
10664 unsigned NElts = VTy->getNumElements();
10665
10666 const Expr *SE = E->getSubExpr();
10667 QualType SETy = SE->getType();
10668
10669 switch (E->getCastKind()) {
10670 case CK_VectorSplat: {
10671 APValue Val = APValue();
10672 if (SETy->isIntegerType()) {
10673 APSInt IntResult;
10674 if (!EvaluateInteger(SE, IntResult, Info))
10675 return false;
10676 Val = APValue(std::move(IntResult));
10677 } else if (SETy->isRealFloatingType()) {
10678 APFloat FloatResult(0.0);
10679 if (!EvaluateFloat(SE, FloatResult, Info))
10680 return false;
10681 Val = APValue(std::move(FloatResult));
10682 } else {
10683 return Error(E);
10684 }
10685
10686 // Splat and create vector APValue.
10687 SmallVector<APValue, 4> Elts(NElts, Val);
10688 return Success(Elts, E);
10689 }
10690 case CK_BitCast: {
10691 APValue SVal;
10692 if (!Evaluate(SVal, Info, SE))
10693 return false;
10694
10695 if (!SVal.isInt() && !SVal.isFloat() && !SVal.isVector()) {
10696 // Give up if the input isn't an int, float, or vector. For example, we
10697 // reject "(v4i16)(intptr_t)&a".
10698 Info.FFDiag(E, diag::note_constexpr_invalid_cast)
10699 << 2 << Info.Ctx.getLangOpts().CPlusPlus;
10700 return false;
10701 }
10702
10703 if (!handleRValueToRValueBitCast(Info, Result, SVal, E))
10704 return false;
10705
10706 return true;
10707 }
10708 default:
10709 return ExprEvaluatorBaseTy::VisitCastExpr(E);
10710 }
10711 }
10712
10713 bool
VisitInitListExpr(const InitListExpr * E)10714 VectorExprEvaluator::VisitInitListExpr(const InitListExpr *E) {
10715 const VectorType *VT = E->getType()->castAs<VectorType>();
10716 unsigned NumInits = E->getNumInits();
10717 unsigned NumElements = VT->getNumElements();
10718
10719 QualType EltTy = VT->getElementType();
10720 SmallVector<APValue, 4> Elements;
10721
10722 // The number of initializers can be less than the number of
10723 // vector elements. For OpenCL, this can be due to nested vector
10724 // initialization. For GCC compatibility, missing trailing elements
10725 // should be initialized with zeroes.
10726 unsigned CountInits = 0, CountElts = 0;
10727 while (CountElts < NumElements) {
10728 // Handle nested vector initialization.
10729 if (CountInits < NumInits
10730 && E->getInit(CountInits)->getType()->isVectorType()) {
10731 APValue v;
10732 if (!EvaluateVector(E->getInit(CountInits), v, Info))
10733 return Error(E);
10734 unsigned vlen = v.getVectorLength();
10735 for (unsigned j = 0; j < vlen; j++)
10736 Elements.push_back(v.getVectorElt(j));
10737 CountElts += vlen;
10738 } else if (EltTy->isIntegerType()) {
10739 llvm::APSInt sInt(32);
10740 if (CountInits < NumInits) {
10741 if (!EvaluateInteger(E->getInit(CountInits), sInt, Info))
10742 return false;
10743 } else // trailing integer zero.
10744 sInt = Info.Ctx.MakeIntValue(0, EltTy);
10745 Elements.push_back(APValue(sInt));
10746 CountElts++;
10747 } else {
10748 llvm::APFloat f(0.0);
10749 if (CountInits < NumInits) {
10750 if (!EvaluateFloat(E->getInit(CountInits), f, Info))
10751 return false;
10752 } else // trailing float zero.
10753 f = APFloat::getZero(Info.Ctx.getFloatTypeSemantics(EltTy));
10754 Elements.push_back(APValue(f));
10755 CountElts++;
10756 }
10757 CountInits++;
10758 }
10759 return Success(Elements, E);
10760 }
10761
10762 bool
ZeroInitialization(const Expr * E)10763 VectorExprEvaluator::ZeroInitialization(const Expr *E) {
10764 const auto *VT = E->getType()->castAs<VectorType>();
10765 QualType EltTy = VT->getElementType();
10766 APValue ZeroElement;
10767 if (EltTy->isIntegerType())
10768 ZeroElement = APValue(Info.Ctx.MakeIntValue(0, EltTy));
10769 else
10770 ZeroElement =
10771 APValue(APFloat::getZero(Info.Ctx.getFloatTypeSemantics(EltTy)));
10772
10773 SmallVector<APValue, 4> Elements(VT->getNumElements(), ZeroElement);
10774 return Success(Elements, E);
10775 }
10776
VisitUnaryImag(const UnaryOperator * E)10777 bool VectorExprEvaluator::VisitUnaryImag(const UnaryOperator *E) {
10778 VisitIgnoredValue(E->getSubExpr());
10779 return ZeroInitialization(E);
10780 }
10781
VisitBinaryOperator(const BinaryOperator * E)10782 bool VectorExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
10783 BinaryOperatorKind Op = E->getOpcode();
10784 assert(Op != BO_PtrMemD && Op != BO_PtrMemI && Op != BO_Cmp &&
10785 "Operation not supported on vector types");
10786
10787 if (Op == BO_Comma)
10788 return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
10789
10790 Expr *LHS = E->getLHS();
10791 Expr *RHS = E->getRHS();
10792
10793 assert(LHS->getType()->isVectorType() && RHS->getType()->isVectorType() &&
10794 "Must both be vector types");
10795 // Checking JUST the types are the same would be fine, except shifts don't
10796 // need to have their types be the same (since you always shift by an int).
10797 assert(LHS->getType()->castAs<VectorType>()->getNumElements() ==
10798 E->getType()->castAs<VectorType>()->getNumElements() &&
10799 RHS->getType()->castAs<VectorType>()->getNumElements() ==
10800 E->getType()->castAs<VectorType>()->getNumElements() &&
10801 "All operands must be the same size.");
10802
10803 APValue LHSValue;
10804 APValue RHSValue;
10805 bool LHSOK = Evaluate(LHSValue, Info, LHS);
10806 if (!LHSOK && !Info.noteFailure())
10807 return false;
10808 if (!Evaluate(RHSValue, Info, RHS) || !LHSOK)
10809 return false;
10810
10811 if (!handleVectorVectorBinOp(Info, E, Op, LHSValue, RHSValue))
10812 return false;
10813
10814 return Success(LHSValue, E);
10815 }
10816
handleVectorUnaryOperator(ASTContext & Ctx,QualType ResultTy,UnaryOperatorKind Op,APValue Elt)10817 static std::optional<APValue> handleVectorUnaryOperator(ASTContext &Ctx,
10818 QualType ResultTy,
10819 UnaryOperatorKind Op,
10820 APValue Elt) {
10821 switch (Op) {
10822 case UO_Plus:
10823 // Nothing to do here.
10824 return Elt;
10825 case UO_Minus:
10826 if (Elt.getKind() == APValue::Int) {
10827 Elt.getInt().negate();
10828 } else {
10829 assert(Elt.getKind() == APValue::Float &&
10830 "Vector can only be int or float type");
10831 Elt.getFloat().changeSign();
10832 }
10833 return Elt;
10834 case UO_Not:
10835 // This is only valid for integral types anyway, so we don't have to handle
10836 // float here.
10837 assert(Elt.getKind() == APValue::Int &&
10838 "Vector operator ~ can only be int");
10839 Elt.getInt().flipAllBits();
10840 return Elt;
10841 case UO_LNot: {
10842 if (Elt.getKind() == APValue::Int) {
10843 Elt.getInt() = !Elt.getInt();
10844 // operator ! on vectors returns -1 for 'truth', so negate it.
10845 Elt.getInt().negate();
10846 return Elt;
10847 }
10848 assert(Elt.getKind() == APValue::Float &&
10849 "Vector can only be int or float type");
10850 // Float types result in an int of the same size, but -1 for true, or 0 for
10851 // false.
10852 APSInt EltResult{Ctx.getIntWidth(ResultTy),
10853 ResultTy->isUnsignedIntegerType()};
10854 if (Elt.getFloat().isZero())
10855 EltResult.setAllBits();
10856 else
10857 EltResult.clearAllBits();
10858
10859 return APValue{EltResult};
10860 }
10861 default:
10862 // FIXME: Implement the rest of the unary operators.
10863 return std::nullopt;
10864 }
10865 }
10866
VisitUnaryOperator(const UnaryOperator * E)10867 bool VectorExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) {
10868 Expr *SubExpr = E->getSubExpr();
10869 const auto *VD = SubExpr->getType()->castAs<VectorType>();
10870 // This result element type differs in the case of negating a floating point
10871 // vector, since the result type is the a vector of the equivilant sized
10872 // integer.
10873 const QualType ResultEltTy = VD->getElementType();
10874 UnaryOperatorKind Op = E->getOpcode();
10875
10876 APValue SubExprValue;
10877 if (!Evaluate(SubExprValue, Info, SubExpr))
10878 return false;
10879
10880 // FIXME: This vector evaluator someday needs to be changed to be LValue
10881 // aware/keep LValue information around, rather than dealing with just vector
10882 // types directly. Until then, we cannot handle cases where the operand to
10883 // these unary operators is an LValue. The only case I've been able to see
10884 // cause this is operator++ assigning to a member expression (only valid in
10885 // altivec compilations) in C mode, so this shouldn't limit us too much.
10886 if (SubExprValue.isLValue())
10887 return false;
10888
10889 assert(SubExprValue.getVectorLength() == VD->getNumElements() &&
10890 "Vector length doesn't match type?");
10891
10892 SmallVector<APValue, 4> ResultElements;
10893 for (unsigned EltNum = 0; EltNum < VD->getNumElements(); ++EltNum) {
10894 std::optional<APValue> Elt = handleVectorUnaryOperator(
10895 Info.Ctx, ResultEltTy, Op, SubExprValue.getVectorElt(EltNum));
10896 if (!Elt)
10897 return false;
10898 ResultElements.push_back(*Elt);
10899 }
10900 return Success(APValue(ResultElements.data(), ResultElements.size()), E);
10901 }
10902
10903 //===----------------------------------------------------------------------===//
10904 // Array Evaluation
10905 //===----------------------------------------------------------------------===//
10906
10907 namespace {
10908 class ArrayExprEvaluator
10909 : public ExprEvaluatorBase<ArrayExprEvaluator> {
10910 const LValue &This;
10911 APValue &Result;
10912 public:
10913
ArrayExprEvaluator(EvalInfo & Info,const LValue & This,APValue & Result)10914 ArrayExprEvaluator(EvalInfo &Info, const LValue &This, APValue &Result)
10915 : ExprEvaluatorBaseTy(Info), This(This), Result(Result) {}
10916
Success(const APValue & V,const Expr * E)10917 bool Success(const APValue &V, const Expr *E) {
10918 assert(V.isArray() && "expected array");
10919 Result = V;
10920 return true;
10921 }
10922
ZeroInitialization(const Expr * E)10923 bool ZeroInitialization(const Expr *E) {
10924 const ConstantArrayType *CAT =
10925 Info.Ctx.getAsConstantArrayType(E->getType());
10926 if (!CAT) {
10927 if (E->getType()->isIncompleteArrayType()) {
10928 // We can be asked to zero-initialize a flexible array member; this
10929 // is represented as an ImplicitValueInitExpr of incomplete array
10930 // type. In this case, the array has zero elements.
10931 Result = APValue(APValue::UninitArray(), 0, 0);
10932 return true;
10933 }
10934 // FIXME: We could handle VLAs here.
10935 return Error(E);
10936 }
10937
10938 Result = APValue(APValue::UninitArray(), 0,
10939 CAT->getSize().getZExtValue());
10940 if (!Result.hasArrayFiller())
10941 return true;
10942
10943 // Zero-initialize all elements.
10944 LValue Subobject = This;
10945 Subobject.addArray(Info, E, CAT);
10946 ImplicitValueInitExpr VIE(CAT->getElementType());
10947 return EvaluateInPlace(Result.getArrayFiller(), Info, Subobject, &VIE);
10948 }
10949
VisitCallExpr(const CallExpr * E)10950 bool VisitCallExpr(const CallExpr *E) {
10951 return handleCallExpr(E, Result, &This);
10952 }
10953 bool VisitInitListExpr(const InitListExpr *E,
10954 QualType AllocType = QualType());
10955 bool VisitArrayInitLoopExpr(const ArrayInitLoopExpr *E);
10956 bool VisitCXXConstructExpr(const CXXConstructExpr *E);
10957 bool VisitCXXConstructExpr(const CXXConstructExpr *E,
10958 const LValue &Subobject,
10959 APValue *Value, QualType Type);
VisitStringLiteral(const StringLiteral * E,QualType AllocType=QualType ())10960 bool VisitStringLiteral(const StringLiteral *E,
10961 QualType AllocType = QualType()) {
10962 expandStringLiteral(Info, E, Result, AllocType);
10963 return true;
10964 }
10965 bool VisitCXXParenListInitExpr(const CXXParenListInitExpr *E);
10966 bool VisitCXXParenListOrInitListExpr(const Expr *ExprToVisit,
10967 ArrayRef<Expr *> Args,
10968 const Expr *ArrayFiller,
10969 QualType AllocType = QualType());
10970 };
10971 } // end anonymous namespace
10972
EvaluateArray(const Expr * E,const LValue & This,APValue & Result,EvalInfo & Info)10973 static bool EvaluateArray(const Expr *E, const LValue &This,
10974 APValue &Result, EvalInfo &Info) {
10975 assert(!E->isValueDependent());
10976 assert(E->isPRValue() && E->getType()->isArrayType() &&
10977 "not an array prvalue");
10978 return ArrayExprEvaluator(Info, This, Result).Visit(E);
10979 }
10980
EvaluateArrayNewInitList(EvalInfo & Info,LValue & This,APValue & Result,const InitListExpr * ILE,QualType AllocType)10981 static bool EvaluateArrayNewInitList(EvalInfo &Info, LValue &This,
10982 APValue &Result, const InitListExpr *ILE,
10983 QualType AllocType) {
10984 assert(!ILE->isValueDependent());
10985 assert(ILE->isPRValue() && ILE->getType()->isArrayType() &&
10986 "not an array prvalue");
10987 return ArrayExprEvaluator(Info, This, Result)
10988 .VisitInitListExpr(ILE, AllocType);
10989 }
10990
EvaluateArrayNewConstructExpr(EvalInfo & Info,LValue & This,APValue & Result,const CXXConstructExpr * CCE,QualType AllocType)10991 static bool EvaluateArrayNewConstructExpr(EvalInfo &Info, LValue &This,
10992 APValue &Result,
10993 const CXXConstructExpr *CCE,
10994 QualType AllocType) {
10995 assert(!CCE->isValueDependent());
10996 assert(CCE->isPRValue() && CCE->getType()->isArrayType() &&
10997 "not an array prvalue");
10998 return ArrayExprEvaluator(Info, This, Result)
10999 .VisitCXXConstructExpr(CCE, This, &Result, AllocType);
11000 }
11001
11002 // Return true iff the given array filler may depend on the element index.
MaybeElementDependentArrayFiller(const Expr * FillerExpr)11003 static bool MaybeElementDependentArrayFiller(const Expr *FillerExpr) {
11004 // For now, just allow non-class value-initialization and initialization
11005 // lists comprised of them.
11006 if (isa<ImplicitValueInitExpr>(FillerExpr))
11007 return false;
11008 if (const InitListExpr *ILE = dyn_cast<InitListExpr>(FillerExpr)) {
11009 for (unsigned I = 0, E = ILE->getNumInits(); I != E; ++I) {
11010 if (MaybeElementDependentArrayFiller(ILE->getInit(I)))
11011 return true;
11012 }
11013
11014 if (ILE->hasArrayFiller() &&
11015 MaybeElementDependentArrayFiller(ILE->getArrayFiller()))
11016 return true;
11017
11018 return false;
11019 }
11020 return true;
11021 }
11022
VisitInitListExpr(const InitListExpr * E,QualType AllocType)11023 bool ArrayExprEvaluator::VisitInitListExpr(const InitListExpr *E,
11024 QualType AllocType) {
11025 const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(
11026 AllocType.isNull() ? E->getType() : AllocType);
11027 if (!CAT)
11028 return Error(E);
11029
11030 // C++11 [dcl.init.string]p1: A char array [...] can be initialized by [...]
11031 // an appropriately-typed string literal enclosed in braces.
11032 if (E->isStringLiteralInit()) {
11033 auto *SL = dyn_cast<StringLiteral>(E->getInit(0)->IgnoreParenImpCasts());
11034 // FIXME: Support ObjCEncodeExpr here once we support it in
11035 // ArrayExprEvaluator generally.
11036 if (!SL)
11037 return Error(E);
11038 return VisitStringLiteral(SL, AllocType);
11039 }
11040 // Any other transparent list init will need proper handling of the
11041 // AllocType; we can't just recurse to the inner initializer.
11042 assert(!E->isTransparent() &&
11043 "transparent array list initialization is not string literal init?");
11044
11045 return VisitCXXParenListOrInitListExpr(E, E->inits(), E->getArrayFiller(),
11046 AllocType);
11047 }
11048
VisitCXXParenListOrInitListExpr(const Expr * ExprToVisit,ArrayRef<Expr * > Args,const Expr * ArrayFiller,QualType AllocType)11049 bool ArrayExprEvaluator::VisitCXXParenListOrInitListExpr(
11050 const Expr *ExprToVisit, ArrayRef<Expr *> Args, const Expr *ArrayFiller,
11051 QualType AllocType) {
11052 const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(
11053 AllocType.isNull() ? ExprToVisit->getType() : AllocType);
11054
11055 bool Success = true;
11056
11057 assert((!Result.isArray() || Result.getArrayInitializedElts() == 0) &&
11058 "zero-initialized array shouldn't have any initialized elts");
11059 APValue Filler;
11060 if (Result.isArray() && Result.hasArrayFiller())
11061 Filler = Result.getArrayFiller();
11062
11063 unsigned NumEltsToInit = Args.size();
11064 unsigned NumElts = CAT->getSize().getZExtValue();
11065
11066 // If the initializer might depend on the array index, run it for each
11067 // array element.
11068 if (NumEltsToInit != NumElts && MaybeElementDependentArrayFiller(ArrayFiller))
11069 NumEltsToInit = NumElts;
11070
11071 LLVM_DEBUG(llvm::dbgs() << "The number of elements to initialize: "
11072 << NumEltsToInit << ".\n");
11073
11074 Result = APValue(APValue::UninitArray(), NumEltsToInit, NumElts);
11075
11076 // If the array was previously zero-initialized, preserve the
11077 // zero-initialized values.
11078 if (Filler.hasValue()) {
11079 for (unsigned I = 0, E = Result.getArrayInitializedElts(); I != E; ++I)
11080 Result.getArrayInitializedElt(I) = Filler;
11081 if (Result.hasArrayFiller())
11082 Result.getArrayFiller() = Filler;
11083 }
11084
11085 LValue Subobject = This;
11086 Subobject.addArray(Info, ExprToVisit, CAT);
11087 for (unsigned Index = 0; Index != NumEltsToInit; ++Index) {
11088 const Expr *Init = Index < Args.size() ? Args[Index] : ArrayFiller;
11089 if (!EvaluateInPlace(Result.getArrayInitializedElt(Index),
11090 Info, Subobject, Init) ||
11091 !HandleLValueArrayAdjustment(Info, Init, Subobject,
11092 CAT->getElementType(), 1)) {
11093 if (!Info.noteFailure())
11094 return false;
11095 Success = false;
11096 }
11097 }
11098
11099 if (!Result.hasArrayFiller())
11100 return Success;
11101
11102 // If we get here, we have a trivial filler, which we can just evaluate
11103 // once and splat over the rest of the array elements.
11104 assert(ArrayFiller && "no array filler for incomplete init list");
11105 return EvaluateInPlace(Result.getArrayFiller(), Info, Subobject,
11106 ArrayFiller) &&
11107 Success;
11108 }
11109
VisitArrayInitLoopExpr(const ArrayInitLoopExpr * E)11110 bool ArrayExprEvaluator::VisitArrayInitLoopExpr(const ArrayInitLoopExpr *E) {
11111 LValue CommonLV;
11112 if (E->getCommonExpr() &&
11113 !Evaluate(Info.CurrentCall->createTemporary(
11114 E->getCommonExpr(),
11115 getStorageType(Info.Ctx, E->getCommonExpr()),
11116 ScopeKind::FullExpression, CommonLV),
11117 Info, E->getCommonExpr()->getSourceExpr()))
11118 return false;
11119
11120 auto *CAT = cast<ConstantArrayType>(E->getType()->castAsArrayTypeUnsafe());
11121
11122 uint64_t Elements = CAT->getSize().getZExtValue();
11123 Result = APValue(APValue::UninitArray(), Elements, Elements);
11124
11125 LValue Subobject = This;
11126 Subobject.addArray(Info, E, CAT);
11127
11128 bool Success = true;
11129 for (EvalInfo::ArrayInitLoopIndex Index(Info); Index != Elements; ++Index) {
11130 // C++ [class.temporary]/5
11131 // There are four contexts in which temporaries are destroyed at a different
11132 // point than the end of the full-expression. [...] The second context is
11133 // when a copy constructor is called to copy an element of an array while
11134 // the entire array is copied [...]. In either case, if the constructor has
11135 // one or more default arguments, the destruction of every temporary created
11136 // in a default argument is sequenced before the construction of the next
11137 // array element, if any.
11138 FullExpressionRAII Scope(Info);
11139
11140 if (!EvaluateInPlace(Result.getArrayInitializedElt(Index),
11141 Info, Subobject, E->getSubExpr()) ||
11142 !HandleLValueArrayAdjustment(Info, E, Subobject,
11143 CAT->getElementType(), 1)) {
11144 if (!Info.noteFailure())
11145 return false;
11146 Success = false;
11147 }
11148
11149 // Make sure we run the destructors too.
11150 Scope.destroy();
11151 }
11152
11153 return Success;
11154 }
11155
VisitCXXConstructExpr(const CXXConstructExpr * E)11156 bool ArrayExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E) {
11157 return VisitCXXConstructExpr(E, This, &Result, E->getType());
11158 }
11159
VisitCXXConstructExpr(const CXXConstructExpr * E,const LValue & Subobject,APValue * Value,QualType Type)11160 bool ArrayExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E,
11161 const LValue &Subobject,
11162 APValue *Value,
11163 QualType Type) {
11164 bool HadZeroInit = Value->hasValue();
11165
11166 if (const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(Type)) {
11167 unsigned FinalSize = CAT->getSize().getZExtValue();
11168
11169 // Preserve the array filler if we had prior zero-initialization.
11170 APValue Filler =
11171 HadZeroInit && Value->hasArrayFiller() ? Value->getArrayFiller()
11172 : APValue();
11173
11174 *Value = APValue(APValue::UninitArray(), 0, FinalSize);
11175 if (FinalSize == 0)
11176 return true;
11177
11178 bool HasTrivialConstructor = CheckTrivialDefaultConstructor(
11179 Info, E->getExprLoc(), E->getConstructor(),
11180 E->requiresZeroInitialization());
11181 LValue ArrayElt = Subobject;
11182 ArrayElt.addArray(Info, E, CAT);
11183 // We do the whole initialization in two passes, first for just one element,
11184 // then for the whole array. It's possible we may find out we can't do const
11185 // init in the first pass, in which case we avoid allocating a potentially
11186 // large array. We don't do more passes because expanding array requires
11187 // copying the data, which is wasteful.
11188 for (const unsigned N : {1u, FinalSize}) {
11189 unsigned OldElts = Value->getArrayInitializedElts();
11190 if (OldElts == N)
11191 break;
11192
11193 // Expand the array to appropriate size.
11194 APValue NewValue(APValue::UninitArray(), N, FinalSize);
11195 for (unsigned I = 0; I < OldElts; ++I)
11196 NewValue.getArrayInitializedElt(I).swap(
11197 Value->getArrayInitializedElt(I));
11198 Value->swap(NewValue);
11199
11200 if (HadZeroInit)
11201 for (unsigned I = OldElts; I < N; ++I)
11202 Value->getArrayInitializedElt(I) = Filler;
11203
11204 if (HasTrivialConstructor && N == FinalSize && FinalSize != 1) {
11205 // If we have a trivial constructor, only evaluate it once and copy
11206 // the result into all the array elements.
11207 APValue &FirstResult = Value->getArrayInitializedElt(0);
11208 for (unsigned I = OldElts; I < FinalSize; ++I)
11209 Value->getArrayInitializedElt(I) = FirstResult;
11210 } else {
11211 for (unsigned I = OldElts; I < N; ++I) {
11212 if (!VisitCXXConstructExpr(E, ArrayElt,
11213 &Value->getArrayInitializedElt(I),
11214 CAT->getElementType()) ||
11215 !HandleLValueArrayAdjustment(Info, E, ArrayElt,
11216 CAT->getElementType(), 1))
11217 return false;
11218 // When checking for const initilization any diagnostic is considered
11219 // an error.
11220 if (Info.EvalStatus.Diag && !Info.EvalStatus.Diag->empty() &&
11221 !Info.keepEvaluatingAfterFailure())
11222 return false;
11223 }
11224 }
11225 }
11226
11227 return true;
11228 }
11229
11230 if (!Type->isRecordType())
11231 return Error(E);
11232
11233 return RecordExprEvaluator(Info, Subobject, *Value)
11234 .VisitCXXConstructExpr(E, Type);
11235 }
11236
VisitCXXParenListInitExpr(const CXXParenListInitExpr * E)11237 bool ArrayExprEvaluator::VisitCXXParenListInitExpr(
11238 const CXXParenListInitExpr *E) {
11239 assert(dyn_cast<ConstantArrayType>(E->getType()) &&
11240 "Expression result is not a constant array type");
11241
11242 return VisitCXXParenListOrInitListExpr(E, E->getInitExprs(),
11243 E->getArrayFiller());
11244 }
11245
11246 //===----------------------------------------------------------------------===//
11247 // Integer Evaluation
11248 //
11249 // As a GNU extension, we support casting pointers to sufficiently-wide integer
11250 // types and back in constant folding. Integer values are thus represented
11251 // either as an integer-valued APValue, or as an lvalue-valued APValue.
11252 //===----------------------------------------------------------------------===//
11253
11254 namespace {
11255 class IntExprEvaluator
11256 : public ExprEvaluatorBase<IntExprEvaluator> {
11257 APValue &Result;
11258 public:
IntExprEvaluator(EvalInfo & info,APValue & result)11259 IntExprEvaluator(EvalInfo &info, APValue &result)
11260 : ExprEvaluatorBaseTy(info), Result(result) {}
11261
Success(const llvm::APSInt & SI,const Expr * E,APValue & Result)11262 bool Success(const llvm::APSInt &SI, const Expr *E, APValue &Result) {
11263 assert(E->getType()->isIntegralOrEnumerationType() &&
11264 "Invalid evaluation result.");
11265 assert(SI.isSigned() == E->getType()->isSignedIntegerOrEnumerationType() &&
11266 "Invalid evaluation result.");
11267 assert(SI.getBitWidth() == Info.Ctx.getIntWidth(E->getType()) &&
11268 "Invalid evaluation result.");
11269 Result = APValue(SI);
11270 return true;
11271 }
Success(const llvm::APSInt & SI,const Expr * E)11272 bool Success(const llvm::APSInt &SI, const Expr *E) {
11273 return Success(SI, E, Result);
11274 }
11275
Success(const llvm::APInt & I,const Expr * E,APValue & Result)11276 bool Success(const llvm::APInt &I, const Expr *E, APValue &Result) {
11277 assert(E->getType()->isIntegralOrEnumerationType() &&
11278 "Invalid evaluation result.");
11279 assert(I.getBitWidth() == Info.Ctx.getIntWidth(E->getType()) &&
11280 "Invalid evaluation result.");
11281 Result = APValue(APSInt(I));
11282 Result.getInt().setIsUnsigned(
11283 E->getType()->isUnsignedIntegerOrEnumerationType());
11284 return true;
11285 }
Success(const llvm::APInt & I,const Expr * E)11286 bool Success(const llvm::APInt &I, const Expr *E) {
11287 return Success(I, E, Result);
11288 }
11289
Success(uint64_t Value,const Expr * E,APValue & Result)11290 bool Success(uint64_t Value, const Expr *E, APValue &Result) {
11291 assert(E->getType()->isIntegralOrEnumerationType() &&
11292 "Invalid evaluation result.");
11293 Result = APValue(Info.Ctx.MakeIntValue(Value, E->getType()));
11294 return true;
11295 }
Success(uint64_t Value,const Expr * E)11296 bool Success(uint64_t Value, const Expr *E) {
11297 return Success(Value, E, Result);
11298 }
11299
Success(CharUnits Size,const Expr * E)11300 bool Success(CharUnits Size, const Expr *E) {
11301 return Success(Size.getQuantity(), E);
11302 }
11303
Success(const APValue & V,const Expr * E)11304 bool Success(const APValue &V, const Expr *E) {
11305 if (V.isLValue() || V.isAddrLabelDiff() || V.isIndeterminate()) {
11306 Result = V;
11307 return true;
11308 }
11309 return Success(V.getInt(), E);
11310 }
11311
ZeroInitialization(const Expr * E)11312 bool ZeroInitialization(const Expr *E) { return Success(0, E); }
11313
11314 //===--------------------------------------------------------------------===//
11315 // Visitor Methods
11316 //===--------------------------------------------------------------------===//
11317
VisitIntegerLiteral(const IntegerLiteral * E)11318 bool VisitIntegerLiteral(const IntegerLiteral *E) {
11319 return Success(E->getValue(), E);
11320 }
VisitCharacterLiteral(const CharacterLiteral * E)11321 bool VisitCharacterLiteral(const CharacterLiteral *E) {
11322 return Success(E->getValue(), E);
11323 }
11324
11325 bool CheckReferencedDecl(const Expr *E, const Decl *D);
VisitDeclRefExpr(const DeclRefExpr * E)11326 bool VisitDeclRefExpr(const DeclRefExpr *E) {
11327 if (CheckReferencedDecl(E, E->getDecl()))
11328 return true;
11329
11330 return ExprEvaluatorBaseTy::VisitDeclRefExpr(E);
11331 }
VisitMemberExpr(const MemberExpr * E)11332 bool VisitMemberExpr(const MemberExpr *E) {
11333 if (CheckReferencedDecl(E, E->getMemberDecl())) {
11334 VisitIgnoredBaseExpression(E->getBase());
11335 return true;
11336 }
11337
11338 return ExprEvaluatorBaseTy::VisitMemberExpr(E);
11339 }
11340
11341 bool VisitCallExpr(const CallExpr *E);
11342 bool VisitBuiltinCallExpr(const CallExpr *E, unsigned BuiltinOp);
11343 bool VisitBinaryOperator(const BinaryOperator *E);
11344 bool VisitOffsetOfExpr(const OffsetOfExpr *E);
11345 bool VisitUnaryOperator(const UnaryOperator *E);
11346
11347 bool VisitCastExpr(const CastExpr* E);
11348 bool VisitUnaryExprOrTypeTraitExpr(const UnaryExprOrTypeTraitExpr *E);
11349
VisitCXXBoolLiteralExpr(const CXXBoolLiteralExpr * E)11350 bool VisitCXXBoolLiteralExpr(const CXXBoolLiteralExpr *E) {
11351 return Success(E->getValue(), E);
11352 }
11353
VisitObjCBoolLiteralExpr(const ObjCBoolLiteralExpr * E)11354 bool VisitObjCBoolLiteralExpr(const ObjCBoolLiteralExpr *E) {
11355 return Success(E->getValue(), E);
11356 }
11357
VisitArrayInitIndexExpr(const ArrayInitIndexExpr * E)11358 bool VisitArrayInitIndexExpr(const ArrayInitIndexExpr *E) {
11359 if (Info.ArrayInitIndex == uint64_t(-1)) {
11360 // We were asked to evaluate this subexpression independent of the
11361 // enclosing ArrayInitLoopExpr. We can't do that.
11362 Info.FFDiag(E);
11363 return false;
11364 }
11365 return Success(Info.ArrayInitIndex, E);
11366 }
11367
11368 // Note, GNU defines __null as an integer, not a pointer.
VisitGNUNullExpr(const GNUNullExpr * E)11369 bool VisitGNUNullExpr(const GNUNullExpr *E) {
11370 return ZeroInitialization(E);
11371 }
11372
VisitTypeTraitExpr(const TypeTraitExpr * E)11373 bool VisitTypeTraitExpr(const TypeTraitExpr *E) {
11374 return Success(E->getValue(), E);
11375 }
11376
VisitArrayTypeTraitExpr(const ArrayTypeTraitExpr * E)11377 bool VisitArrayTypeTraitExpr(const ArrayTypeTraitExpr *E) {
11378 return Success(E->getValue(), E);
11379 }
11380
VisitExpressionTraitExpr(const ExpressionTraitExpr * E)11381 bool VisitExpressionTraitExpr(const ExpressionTraitExpr *E) {
11382 return Success(E->getValue(), E);
11383 }
11384
11385 bool VisitUnaryReal(const UnaryOperator *E);
11386 bool VisitUnaryImag(const UnaryOperator *E);
11387
11388 bool VisitCXXNoexceptExpr(const CXXNoexceptExpr *E);
11389 bool VisitSizeOfPackExpr(const SizeOfPackExpr *E);
11390 bool VisitSourceLocExpr(const SourceLocExpr *E);
11391 bool VisitConceptSpecializationExpr(const ConceptSpecializationExpr *E);
11392 bool VisitRequiresExpr(const RequiresExpr *E);
11393 // FIXME: Missing: array subscript of vector, member of vector
11394 };
11395
11396 class FixedPointExprEvaluator
11397 : public ExprEvaluatorBase<FixedPointExprEvaluator> {
11398 APValue &Result;
11399
11400 public:
FixedPointExprEvaluator(EvalInfo & info,APValue & result)11401 FixedPointExprEvaluator(EvalInfo &info, APValue &result)
11402 : ExprEvaluatorBaseTy(info), Result(result) {}
11403
Success(const llvm::APInt & I,const Expr * E)11404 bool Success(const llvm::APInt &I, const Expr *E) {
11405 return Success(
11406 APFixedPoint(I, Info.Ctx.getFixedPointSemantics(E->getType())), E);
11407 }
11408
Success(uint64_t Value,const Expr * E)11409 bool Success(uint64_t Value, const Expr *E) {
11410 return Success(
11411 APFixedPoint(Value, Info.Ctx.getFixedPointSemantics(E->getType())), E);
11412 }
11413
Success(const APValue & V,const Expr * E)11414 bool Success(const APValue &V, const Expr *E) {
11415 return Success(V.getFixedPoint(), E);
11416 }
11417
Success(const APFixedPoint & V,const Expr * E)11418 bool Success(const APFixedPoint &V, const Expr *E) {
11419 assert(E->getType()->isFixedPointType() && "Invalid evaluation result.");
11420 assert(V.getWidth() == Info.Ctx.getIntWidth(E->getType()) &&
11421 "Invalid evaluation result.");
11422 Result = APValue(V);
11423 return true;
11424 }
11425
11426 //===--------------------------------------------------------------------===//
11427 // Visitor Methods
11428 //===--------------------------------------------------------------------===//
11429
VisitFixedPointLiteral(const FixedPointLiteral * E)11430 bool VisitFixedPointLiteral(const FixedPointLiteral *E) {
11431 return Success(E->getValue(), E);
11432 }
11433
11434 bool VisitCastExpr(const CastExpr *E);
11435 bool VisitUnaryOperator(const UnaryOperator *E);
11436 bool VisitBinaryOperator(const BinaryOperator *E);
11437 };
11438 } // end anonymous namespace
11439
11440 /// EvaluateIntegerOrLValue - Evaluate an rvalue integral-typed expression, and
11441 /// produce either the integer value or a pointer.
11442 ///
11443 /// GCC has a heinous extension which folds casts between pointer types and
11444 /// pointer-sized integral types. We support this by allowing the evaluation of
11445 /// an integer rvalue to produce a pointer (represented as an lvalue) instead.
11446 /// Some simple arithmetic on such values is supported (they are treated much
11447 /// like char*).
EvaluateIntegerOrLValue(const Expr * E,APValue & Result,EvalInfo & Info)11448 static bool EvaluateIntegerOrLValue(const Expr *E, APValue &Result,
11449 EvalInfo &Info) {
11450 assert(!E->isValueDependent());
11451 assert(E->isPRValue() && E->getType()->isIntegralOrEnumerationType());
11452 return IntExprEvaluator(Info, Result).Visit(E);
11453 }
11454
EvaluateInteger(const Expr * E,APSInt & Result,EvalInfo & Info)11455 static bool EvaluateInteger(const Expr *E, APSInt &Result, EvalInfo &Info) {
11456 assert(!E->isValueDependent());
11457 APValue Val;
11458 if (!EvaluateIntegerOrLValue(E, Val, Info))
11459 return false;
11460 if (!Val.isInt()) {
11461 // FIXME: It would be better to produce the diagnostic for casting
11462 // a pointer to an integer.
11463 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
11464 return false;
11465 }
11466 Result = Val.getInt();
11467 return true;
11468 }
11469
VisitSourceLocExpr(const SourceLocExpr * E)11470 bool IntExprEvaluator::VisitSourceLocExpr(const SourceLocExpr *E) {
11471 APValue Evaluated = E->EvaluateInContext(
11472 Info.Ctx, Info.CurrentCall->CurSourceLocExprScope.getDefaultExpr());
11473 return Success(Evaluated, E);
11474 }
11475
EvaluateFixedPoint(const Expr * E,APFixedPoint & Result,EvalInfo & Info)11476 static bool EvaluateFixedPoint(const Expr *E, APFixedPoint &Result,
11477 EvalInfo &Info) {
11478 assert(!E->isValueDependent());
11479 if (E->getType()->isFixedPointType()) {
11480 APValue Val;
11481 if (!FixedPointExprEvaluator(Info, Val).Visit(E))
11482 return false;
11483 if (!Val.isFixedPoint())
11484 return false;
11485
11486 Result = Val.getFixedPoint();
11487 return true;
11488 }
11489 return false;
11490 }
11491
EvaluateFixedPointOrInteger(const Expr * E,APFixedPoint & Result,EvalInfo & Info)11492 static bool EvaluateFixedPointOrInteger(const Expr *E, APFixedPoint &Result,
11493 EvalInfo &Info) {
11494 assert(!E->isValueDependent());
11495 if (E->getType()->isIntegerType()) {
11496 auto FXSema = Info.Ctx.getFixedPointSemantics(E->getType());
11497 APSInt Val;
11498 if (!EvaluateInteger(E, Val, Info))
11499 return false;
11500 Result = APFixedPoint(Val, FXSema);
11501 return true;
11502 } else if (E->getType()->isFixedPointType()) {
11503 return EvaluateFixedPoint(E, Result, Info);
11504 }
11505 return false;
11506 }
11507
11508 /// Check whether the given declaration can be directly converted to an integral
11509 /// rvalue. If not, no diagnostic is produced; there are other things we can
11510 /// try.
CheckReferencedDecl(const Expr * E,const Decl * D)11511 bool IntExprEvaluator::CheckReferencedDecl(const Expr* E, const Decl* D) {
11512 // Enums are integer constant exprs.
11513 if (const EnumConstantDecl *ECD = dyn_cast<EnumConstantDecl>(D)) {
11514 // Check for signedness/width mismatches between E type and ECD value.
11515 bool SameSign = (ECD->getInitVal().isSigned()
11516 == E->getType()->isSignedIntegerOrEnumerationType());
11517 bool SameWidth = (ECD->getInitVal().getBitWidth()
11518 == Info.Ctx.getIntWidth(E->getType()));
11519 if (SameSign && SameWidth)
11520 return Success(ECD->getInitVal(), E);
11521 else {
11522 // Get rid of mismatch (otherwise Success assertions will fail)
11523 // by computing a new value matching the type of E.
11524 llvm::APSInt Val = ECD->getInitVal();
11525 if (!SameSign)
11526 Val.setIsSigned(!ECD->getInitVal().isSigned());
11527 if (!SameWidth)
11528 Val = Val.extOrTrunc(Info.Ctx.getIntWidth(E->getType()));
11529 return Success(Val, E);
11530 }
11531 }
11532 return false;
11533 }
11534
11535 /// EvaluateBuiltinClassifyType - Evaluate __builtin_classify_type the same way
11536 /// as GCC.
EvaluateBuiltinClassifyType(QualType T,const LangOptions & LangOpts)11537 GCCTypeClass EvaluateBuiltinClassifyType(QualType T,
11538 const LangOptions &LangOpts) {
11539 assert(!T->isDependentType() && "unexpected dependent type");
11540
11541 QualType CanTy = T.getCanonicalType();
11542
11543 switch (CanTy->getTypeClass()) {
11544 #define TYPE(ID, BASE)
11545 #define DEPENDENT_TYPE(ID, BASE) case Type::ID:
11546 #define NON_CANONICAL_TYPE(ID, BASE) case Type::ID:
11547 #define NON_CANONICAL_UNLESS_DEPENDENT_TYPE(ID, BASE) case Type::ID:
11548 #include "clang/AST/TypeNodes.inc"
11549 case Type::Auto:
11550 case Type::DeducedTemplateSpecialization:
11551 llvm_unreachable("unexpected non-canonical or dependent type");
11552
11553 case Type::Builtin:
11554 switch (cast<BuiltinType>(CanTy)->getKind()) {
11555 #define BUILTIN_TYPE(ID, SINGLETON_ID)
11556 #define SIGNED_TYPE(ID, SINGLETON_ID) \
11557 case BuiltinType::ID: return GCCTypeClass::Integer;
11558 #define FLOATING_TYPE(ID, SINGLETON_ID) \
11559 case BuiltinType::ID: return GCCTypeClass::RealFloat;
11560 #define PLACEHOLDER_TYPE(ID, SINGLETON_ID) \
11561 case BuiltinType::ID: break;
11562 #include "clang/AST/BuiltinTypes.def"
11563 case BuiltinType::Void:
11564 return GCCTypeClass::Void;
11565
11566 case BuiltinType::Bool:
11567 return GCCTypeClass::Bool;
11568
11569 case BuiltinType::Char_U:
11570 case BuiltinType::UChar:
11571 case BuiltinType::WChar_U:
11572 case BuiltinType::Char8:
11573 case BuiltinType::Char16:
11574 case BuiltinType::Char32:
11575 case BuiltinType::UShort:
11576 case BuiltinType::UInt:
11577 case BuiltinType::ULong:
11578 case BuiltinType::ULongLong:
11579 case BuiltinType::UInt128:
11580 return GCCTypeClass::Integer;
11581
11582 case BuiltinType::UShortAccum:
11583 case BuiltinType::UAccum:
11584 case BuiltinType::ULongAccum:
11585 case BuiltinType::UShortFract:
11586 case BuiltinType::UFract:
11587 case BuiltinType::ULongFract:
11588 case BuiltinType::SatUShortAccum:
11589 case BuiltinType::SatUAccum:
11590 case BuiltinType::SatULongAccum:
11591 case BuiltinType::SatUShortFract:
11592 case BuiltinType::SatUFract:
11593 case BuiltinType::SatULongFract:
11594 return GCCTypeClass::None;
11595
11596 case BuiltinType::NullPtr:
11597
11598 case BuiltinType::ObjCId:
11599 case BuiltinType::ObjCClass:
11600 case BuiltinType::ObjCSel:
11601 #define IMAGE_TYPE(ImgType, Id, SingletonId, Access, Suffix) \
11602 case BuiltinType::Id:
11603 #include "clang/Basic/OpenCLImageTypes.def"
11604 #define EXT_OPAQUE_TYPE(ExtType, Id, Ext) \
11605 case BuiltinType::Id:
11606 #include "clang/Basic/OpenCLExtensionTypes.def"
11607 case BuiltinType::OCLSampler:
11608 case BuiltinType::OCLEvent:
11609 case BuiltinType::OCLClkEvent:
11610 case BuiltinType::OCLQueue:
11611 case BuiltinType::OCLReserveID:
11612 #define SVE_TYPE(Name, Id, SingletonId) \
11613 case BuiltinType::Id:
11614 #include "clang/Basic/AArch64SVEACLETypes.def"
11615 #define PPC_VECTOR_TYPE(Name, Id, Size) \
11616 case BuiltinType::Id:
11617 #include "clang/Basic/PPCTypes.def"
11618 #define RVV_TYPE(Name, Id, SingletonId) case BuiltinType::Id:
11619 #include "clang/Basic/RISCVVTypes.def"
11620 #define WASM_TYPE(Name, Id, SingletonId) case BuiltinType::Id:
11621 #include "clang/Basic/WebAssemblyReferenceTypes.def"
11622 return GCCTypeClass::None;
11623
11624 case BuiltinType::Dependent:
11625 llvm_unreachable("unexpected dependent type");
11626 };
11627 llvm_unreachable("unexpected placeholder type");
11628
11629 case Type::Enum:
11630 return LangOpts.CPlusPlus ? GCCTypeClass::Enum : GCCTypeClass::Integer;
11631
11632 case Type::Pointer:
11633 case Type::ConstantArray:
11634 case Type::VariableArray:
11635 case Type::IncompleteArray:
11636 case Type::FunctionNoProto:
11637 case Type::FunctionProto:
11638 return GCCTypeClass::Pointer;
11639
11640 case Type::MemberPointer:
11641 return CanTy->isMemberDataPointerType()
11642 ? GCCTypeClass::PointerToDataMember
11643 : GCCTypeClass::PointerToMemberFunction;
11644
11645 case Type::Complex:
11646 return GCCTypeClass::Complex;
11647
11648 case Type::Record:
11649 return CanTy->isUnionType() ? GCCTypeClass::Union
11650 : GCCTypeClass::ClassOrStruct;
11651
11652 case Type::Atomic:
11653 // GCC classifies _Atomic T the same as T.
11654 return EvaluateBuiltinClassifyType(
11655 CanTy->castAs<AtomicType>()->getValueType(), LangOpts);
11656
11657 case Type::Vector:
11658 case Type::ExtVector:
11659 return GCCTypeClass::Vector;
11660
11661 case Type::BlockPointer:
11662 case Type::ConstantMatrix:
11663 case Type::ObjCObject:
11664 case Type::ObjCInterface:
11665 case Type::ObjCObjectPointer:
11666 case Type::Pipe:
11667 // Classify all other types that don't fit into the regular
11668 // classification the same way.
11669 return GCCTypeClass::None;
11670
11671 case Type::BitInt:
11672 return GCCTypeClass::BitInt;
11673
11674 case Type::LValueReference:
11675 case Type::RValueReference:
11676 llvm_unreachable("invalid type for expression");
11677 }
11678
11679 llvm_unreachable("unexpected type class");
11680 }
11681
11682 /// EvaluateBuiltinClassifyType - Evaluate __builtin_classify_type the same way
11683 /// as GCC.
11684 static GCCTypeClass
EvaluateBuiltinClassifyType(const CallExpr * E,const LangOptions & LangOpts)11685 EvaluateBuiltinClassifyType(const CallExpr *E, const LangOptions &LangOpts) {
11686 // If no argument was supplied, default to None. This isn't
11687 // ideal, however it is what gcc does.
11688 if (E->getNumArgs() == 0)
11689 return GCCTypeClass::None;
11690
11691 // FIXME: Bizarrely, GCC treats a call with more than one argument as not
11692 // being an ICE, but still folds it to a constant using the type of the first
11693 // argument.
11694 return EvaluateBuiltinClassifyType(E->getArg(0)->getType(), LangOpts);
11695 }
11696
11697 /// EvaluateBuiltinConstantPForLValue - Determine the result of
11698 /// __builtin_constant_p when applied to the given pointer.
11699 ///
11700 /// A pointer is only "constant" if it is null (or a pointer cast to integer)
11701 /// or it points to the first character of a string literal.
EvaluateBuiltinConstantPForLValue(const APValue & LV)11702 static bool EvaluateBuiltinConstantPForLValue(const APValue &LV) {
11703 APValue::LValueBase Base = LV.getLValueBase();
11704 if (Base.isNull()) {
11705 // A null base is acceptable.
11706 return true;
11707 } else if (const Expr *E = Base.dyn_cast<const Expr *>()) {
11708 if (!isa<StringLiteral>(E))
11709 return false;
11710 return LV.getLValueOffset().isZero();
11711 } else if (Base.is<TypeInfoLValue>()) {
11712 // Surprisingly, GCC considers __builtin_constant_p(&typeid(int)) to
11713 // evaluate to true.
11714 return true;
11715 } else {
11716 // Any other base is not constant enough for GCC.
11717 return false;
11718 }
11719 }
11720
11721 /// EvaluateBuiltinConstantP - Evaluate __builtin_constant_p as similarly to
11722 /// GCC as we can manage.
EvaluateBuiltinConstantP(EvalInfo & Info,const Expr * Arg)11723 static bool EvaluateBuiltinConstantP(EvalInfo &Info, const Expr *Arg) {
11724 // This evaluation is not permitted to have side-effects, so evaluate it in
11725 // a speculative evaluation context.
11726 SpeculativeEvaluationRAII SpeculativeEval(Info);
11727
11728 // Constant-folding is always enabled for the operand of __builtin_constant_p
11729 // (even when the enclosing evaluation context otherwise requires a strict
11730 // language-specific constant expression).
11731 FoldConstant Fold(Info, true);
11732
11733 QualType ArgType = Arg->getType();
11734
11735 // __builtin_constant_p always has one operand. The rules which gcc follows
11736 // are not precisely documented, but are as follows:
11737 //
11738 // - If the operand is of integral, floating, complex or enumeration type,
11739 // and can be folded to a known value of that type, it returns 1.
11740 // - If the operand can be folded to a pointer to the first character
11741 // of a string literal (or such a pointer cast to an integral type)
11742 // or to a null pointer or an integer cast to a pointer, it returns 1.
11743 //
11744 // Otherwise, it returns 0.
11745 //
11746 // FIXME: GCC also intends to return 1 for literals of aggregate types, but
11747 // its support for this did not work prior to GCC 9 and is not yet well
11748 // understood.
11749 if (ArgType->isIntegralOrEnumerationType() || ArgType->isFloatingType() ||
11750 ArgType->isAnyComplexType() || ArgType->isPointerType() ||
11751 ArgType->isNullPtrType()) {
11752 APValue V;
11753 if (!::EvaluateAsRValue(Info, Arg, V) || Info.EvalStatus.HasSideEffects) {
11754 Fold.keepDiagnostics();
11755 return false;
11756 }
11757
11758 // For a pointer (possibly cast to integer), there are special rules.
11759 if (V.getKind() == APValue::LValue)
11760 return EvaluateBuiltinConstantPForLValue(V);
11761
11762 // Otherwise, any constant value is good enough.
11763 return V.hasValue();
11764 }
11765
11766 // Anything else isn't considered to be sufficiently constant.
11767 return false;
11768 }
11769
11770 /// Retrieves the "underlying object type" of the given expression,
11771 /// as used by __builtin_object_size.
getObjectType(APValue::LValueBase B)11772 static QualType getObjectType(APValue::LValueBase B) {
11773 if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) {
11774 if (const VarDecl *VD = dyn_cast<VarDecl>(D))
11775 return VD->getType();
11776 } else if (const Expr *E = B.dyn_cast<const Expr*>()) {
11777 if (isa<CompoundLiteralExpr>(E))
11778 return E->getType();
11779 } else if (B.is<TypeInfoLValue>()) {
11780 return B.getTypeInfoType();
11781 } else if (B.is<DynamicAllocLValue>()) {
11782 return B.getDynamicAllocType();
11783 }
11784
11785 return QualType();
11786 }
11787
11788 /// A more selective version of E->IgnoreParenCasts for
11789 /// tryEvaluateBuiltinObjectSize. This ignores some casts/parens that serve only
11790 /// to change the type of E.
11791 /// Ex. For E = `(short*)((char*)(&foo))`, returns `&foo`
11792 ///
11793 /// Always returns an RValue with a pointer representation.
ignorePointerCastsAndParens(const Expr * E)11794 static const Expr *ignorePointerCastsAndParens(const Expr *E) {
11795 assert(E->isPRValue() && E->getType()->hasPointerRepresentation());
11796
11797 auto *NoParens = E->IgnoreParens();
11798 auto *Cast = dyn_cast<CastExpr>(NoParens);
11799 if (Cast == nullptr)
11800 return NoParens;
11801
11802 // We only conservatively allow a few kinds of casts, because this code is
11803 // inherently a simple solution that seeks to support the common case.
11804 auto CastKind = Cast->getCastKind();
11805 if (CastKind != CK_NoOp && CastKind != CK_BitCast &&
11806 CastKind != CK_AddressSpaceConversion)
11807 return NoParens;
11808
11809 auto *SubExpr = Cast->getSubExpr();
11810 if (!SubExpr->getType()->hasPointerRepresentation() || !SubExpr->isPRValue())
11811 return NoParens;
11812 return ignorePointerCastsAndParens(SubExpr);
11813 }
11814
11815 /// Checks to see if the given LValue's Designator is at the end of the LValue's
11816 /// record layout. e.g.
11817 /// struct { struct { int a, b; } fst, snd; } obj;
11818 /// obj.fst // no
11819 /// obj.snd // yes
11820 /// obj.fst.a // no
11821 /// obj.fst.b // no
11822 /// obj.snd.a // no
11823 /// obj.snd.b // yes
11824 ///
11825 /// Please note: this function is specialized for how __builtin_object_size
11826 /// views "objects".
11827 ///
11828 /// If this encounters an invalid RecordDecl or otherwise cannot determine the
11829 /// correct result, it will always return true.
isDesignatorAtObjectEnd(const ASTContext & Ctx,const LValue & LVal)11830 static bool isDesignatorAtObjectEnd(const ASTContext &Ctx, const LValue &LVal) {
11831 assert(!LVal.Designator.Invalid);
11832
11833 auto IsLastOrInvalidFieldDecl = [&Ctx](const FieldDecl *FD, bool &Invalid) {
11834 const RecordDecl *Parent = FD->getParent();
11835 Invalid = Parent->isInvalidDecl();
11836 if (Invalid || Parent->isUnion())
11837 return true;
11838 const ASTRecordLayout &Layout = Ctx.getASTRecordLayout(Parent);
11839 return FD->getFieldIndex() + 1 == Layout.getFieldCount();
11840 };
11841
11842 auto &Base = LVal.getLValueBase();
11843 if (auto *ME = dyn_cast_or_null<MemberExpr>(Base.dyn_cast<const Expr *>())) {
11844 if (auto *FD = dyn_cast<FieldDecl>(ME->getMemberDecl())) {
11845 bool Invalid;
11846 if (!IsLastOrInvalidFieldDecl(FD, Invalid))
11847 return Invalid;
11848 } else if (auto *IFD = dyn_cast<IndirectFieldDecl>(ME->getMemberDecl())) {
11849 for (auto *FD : IFD->chain()) {
11850 bool Invalid;
11851 if (!IsLastOrInvalidFieldDecl(cast<FieldDecl>(FD), Invalid))
11852 return Invalid;
11853 }
11854 }
11855 }
11856
11857 unsigned I = 0;
11858 QualType BaseType = getType(Base);
11859 if (LVal.Designator.FirstEntryIsAnUnsizedArray) {
11860 // If we don't know the array bound, conservatively assume we're looking at
11861 // the final array element.
11862 ++I;
11863 if (BaseType->isIncompleteArrayType())
11864 BaseType = Ctx.getAsArrayType(BaseType)->getElementType();
11865 else
11866 BaseType = BaseType->castAs<PointerType>()->getPointeeType();
11867 }
11868
11869 for (unsigned E = LVal.Designator.Entries.size(); I != E; ++I) {
11870 const auto &Entry = LVal.Designator.Entries[I];
11871 if (BaseType->isArrayType()) {
11872 // Because __builtin_object_size treats arrays as objects, we can ignore
11873 // the index iff this is the last array in the Designator.
11874 if (I + 1 == E)
11875 return true;
11876 const auto *CAT = cast<ConstantArrayType>(Ctx.getAsArrayType(BaseType));
11877 uint64_t Index = Entry.getAsArrayIndex();
11878 if (Index + 1 != CAT->getSize())
11879 return false;
11880 BaseType = CAT->getElementType();
11881 } else if (BaseType->isAnyComplexType()) {
11882 const auto *CT = BaseType->castAs<ComplexType>();
11883 uint64_t Index = Entry.getAsArrayIndex();
11884 if (Index != 1)
11885 return false;
11886 BaseType = CT->getElementType();
11887 } else if (auto *FD = getAsField(Entry)) {
11888 bool Invalid;
11889 if (!IsLastOrInvalidFieldDecl(FD, Invalid))
11890 return Invalid;
11891 BaseType = FD->getType();
11892 } else {
11893 assert(getAsBaseClass(Entry) && "Expecting cast to a base class");
11894 return false;
11895 }
11896 }
11897 return true;
11898 }
11899
11900 /// Tests to see if the LValue has a user-specified designator (that isn't
11901 /// necessarily valid). Note that this always returns 'true' if the LValue has
11902 /// an unsized array as its first designator entry, because there's currently no
11903 /// way to tell if the user typed *foo or foo[0].
refersToCompleteObject(const LValue & LVal)11904 static bool refersToCompleteObject(const LValue &LVal) {
11905 if (LVal.Designator.Invalid)
11906 return false;
11907
11908 if (!LVal.Designator.Entries.empty())
11909 return LVal.Designator.isMostDerivedAnUnsizedArray();
11910
11911 if (!LVal.InvalidBase)
11912 return true;
11913
11914 // If `E` is a MemberExpr, then the first part of the designator is hiding in
11915 // the LValueBase.
11916 const auto *E = LVal.Base.dyn_cast<const Expr *>();
11917 return !E || !isa<MemberExpr>(E);
11918 }
11919
11920 /// Attempts to detect a user writing into a piece of memory that's impossible
11921 /// to figure out the size of by just using types.
isUserWritingOffTheEnd(const ASTContext & Ctx,const LValue & LVal)11922 static bool isUserWritingOffTheEnd(const ASTContext &Ctx, const LValue &LVal) {
11923 const SubobjectDesignator &Designator = LVal.Designator;
11924 // Notes:
11925 // - Users can only write off of the end when we have an invalid base. Invalid
11926 // bases imply we don't know where the memory came from.
11927 // - We used to be a bit more aggressive here; we'd only be conservative if
11928 // the array at the end was flexible, or if it had 0 or 1 elements. This
11929 // broke some common standard library extensions (PR30346), but was
11930 // otherwise seemingly fine. It may be useful to reintroduce this behavior
11931 // with some sort of list. OTOH, it seems that GCC is always
11932 // conservative with the last element in structs (if it's an array), so our
11933 // current behavior is more compatible than an explicit list approach would
11934 // be.
11935 auto isFlexibleArrayMember = [&] {
11936 using FAMKind = LangOptions::StrictFlexArraysLevelKind;
11937 FAMKind StrictFlexArraysLevel =
11938 Ctx.getLangOpts().getStrictFlexArraysLevel();
11939
11940 if (Designator.isMostDerivedAnUnsizedArray())
11941 return true;
11942
11943 if (StrictFlexArraysLevel == FAMKind::Default)
11944 return true;
11945
11946 if (Designator.getMostDerivedArraySize() == 0 &&
11947 StrictFlexArraysLevel != FAMKind::IncompleteOnly)
11948 return true;
11949
11950 if (Designator.getMostDerivedArraySize() == 1 &&
11951 StrictFlexArraysLevel == FAMKind::OneZeroOrIncomplete)
11952 return true;
11953
11954 return false;
11955 };
11956
11957 return LVal.InvalidBase &&
11958 Designator.Entries.size() == Designator.MostDerivedPathLength &&
11959 Designator.MostDerivedIsArrayElement && isFlexibleArrayMember() &&
11960 isDesignatorAtObjectEnd(Ctx, LVal);
11961 }
11962
11963 /// Converts the given APInt to CharUnits, assuming the APInt is unsigned.
11964 /// Fails if the conversion would cause loss of precision.
convertUnsignedAPIntToCharUnits(const llvm::APInt & Int,CharUnits & Result)11965 static bool convertUnsignedAPIntToCharUnits(const llvm::APInt &Int,
11966 CharUnits &Result) {
11967 auto CharUnitsMax = std::numeric_limits<CharUnits::QuantityType>::max();
11968 if (Int.ugt(CharUnitsMax))
11969 return false;
11970 Result = CharUnits::fromQuantity(Int.getZExtValue());
11971 return true;
11972 }
11973
11974 /// If we're evaluating the object size of an instance of a struct that
11975 /// contains a flexible array member, add the size of the initializer.
addFlexibleArrayMemberInitSize(EvalInfo & Info,const QualType & T,const LValue & LV,CharUnits & Size)11976 static void addFlexibleArrayMemberInitSize(EvalInfo &Info, const QualType &T,
11977 const LValue &LV, CharUnits &Size) {
11978 if (!T.isNull() && T->isStructureType() &&
11979 T->getAsStructureType()->getDecl()->hasFlexibleArrayMember())
11980 if (const auto *V = LV.getLValueBase().dyn_cast<const ValueDecl *>())
11981 if (const auto *VD = dyn_cast<VarDecl>(V))
11982 if (VD->hasInit())
11983 Size += VD->getFlexibleArrayInitChars(Info.Ctx);
11984 }
11985
11986 /// Helper for tryEvaluateBuiltinObjectSize -- Given an LValue, this will
11987 /// determine how many bytes exist from the beginning of the object to either
11988 /// the end of the current subobject, or the end of the object itself, depending
11989 /// on what the LValue looks like + the value of Type.
11990 ///
11991 /// If this returns false, the value of Result is undefined.
determineEndOffset(EvalInfo & Info,SourceLocation ExprLoc,unsigned Type,const LValue & LVal,CharUnits & EndOffset)11992 static bool determineEndOffset(EvalInfo &Info, SourceLocation ExprLoc,
11993 unsigned Type, const LValue &LVal,
11994 CharUnits &EndOffset) {
11995 bool DetermineForCompleteObject = refersToCompleteObject(LVal);
11996
11997 auto CheckedHandleSizeof = [&](QualType Ty, CharUnits &Result) {
11998 if (Ty.isNull() || Ty->isIncompleteType() || Ty->isFunctionType())
11999 return false;
12000 return HandleSizeof(Info, ExprLoc, Ty, Result);
12001 };
12002
12003 // We want to evaluate the size of the entire object. This is a valid fallback
12004 // for when Type=1 and the designator is invalid, because we're asked for an
12005 // upper-bound.
12006 if (!(Type & 1) || LVal.Designator.Invalid || DetermineForCompleteObject) {
12007 // Type=3 wants a lower bound, so we can't fall back to this.
12008 if (Type == 3 && !DetermineForCompleteObject)
12009 return false;
12010
12011 llvm::APInt APEndOffset;
12012 if (isBaseAnAllocSizeCall(LVal.getLValueBase()) &&
12013 getBytesReturnedByAllocSizeCall(Info.Ctx, LVal, APEndOffset))
12014 return convertUnsignedAPIntToCharUnits(APEndOffset, EndOffset);
12015
12016 if (LVal.InvalidBase)
12017 return false;
12018
12019 QualType BaseTy = getObjectType(LVal.getLValueBase());
12020 const bool Ret = CheckedHandleSizeof(BaseTy, EndOffset);
12021 addFlexibleArrayMemberInitSize(Info, BaseTy, LVal, EndOffset);
12022 return Ret;
12023 }
12024
12025 // We want to evaluate the size of a subobject.
12026 const SubobjectDesignator &Designator = LVal.Designator;
12027
12028 // The following is a moderately common idiom in C:
12029 //
12030 // struct Foo { int a; char c[1]; };
12031 // struct Foo *F = (struct Foo *)malloc(sizeof(struct Foo) + strlen(Bar));
12032 // strcpy(&F->c[0], Bar);
12033 //
12034 // In order to not break too much legacy code, we need to support it.
12035 if (isUserWritingOffTheEnd(Info.Ctx, LVal)) {
12036 // If we can resolve this to an alloc_size call, we can hand that back,
12037 // because we know for certain how many bytes there are to write to.
12038 llvm::APInt APEndOffset;
12039 if (isBaseAnAllocSizeCall(LVal.getLValueBase()) &&
12040 getBytesReturnedByAllocSizeCall(Info.Ctx, LVal, APEndOffset))
12041 return convertUnsignedAPIntToCharUnits(APEndOffset, EndOffset);
12042
12043 // If we cannot determine the size of the initial allocation, then we can't
12044 // given an accurate upper-bound. However, we are still able to give
12045 // conservative lower-bounds for Type=3.
12046 if (Type == 1)
12047 return false;
12048 }
12049
12050 CharUnits BytesPerElem;
12051 if (!CheckedHandleSizeof(Designator.MostDerivedType, BytesPerElem))
12052 return false;
12053
12054 // According to the GCC documentation, we want the size of the subobject
12055 // denoted by the pointer. But that's not quite right -- what we actually
12056 // want is the size of the immediately-enclosing array, if there is one.
12057 int64_t ElemsRemaining;
12058 if (Designator.MostDerivedIsArrayElement &&
12059 Designator.Entries.size() == Designator.MostDerivedPathLength) {
12060 uint64_t ArraySize = Designator.getMostDerivedArraySize();
12061 uint64_t ArrayIndex = Designator.Entries.back().getAsArrayIndex();
12062 ElemsRemaining = ArraySize <= ArrayIndex ? 0 : ArraySize - ArrayIndex;
12063 } else {
12064 ElemsRemaining = Designator.isOnePastTheEnd() ? 0 : 1;
12065 }
12066
12067 EndOffset = LVal.getLValueOffset() + BytesPerElem * ElemsRemaining;
12068 return true;
12069 }
12070
12071 /// Tries to evaluate the __builtin_object_size for @p E. If successful,
12072 /// returns true and stores the result in @p Size.
12073 ///
12074 /// If @p WasError is non-null, this will report whether the failure to evaluate
12075 /// is to be treated as an Error in IntExprEvaluator.
tryEvaluateBuiltinObjectSize(const Expr * E,unsigned Type,EvalInfo & Info,uint64_t & Size)12076 static bool tryEvaluateBuiltinObjectSize(const Expr *E, unsigned Type,
12077 EvalInfo &Info, uint64_t &Size) {
12078 // Determine the denoted object.
12079 LValue LVal;
12080 {
12081 // The operand of __builtin_object_size is never evaluated for side-effects.
12082 // If there are any, but we can determine the pointed-to object anyway, then
12083 // ignore the side-effects.
12084 SpeculativeEvaluationRAII SpeculativeEval(Info);
12085 IgnoreSideEffectsRAII Fold(Info);
12086
12087 if (E->isGLValue()) {
12088 // It's possible for us to be given GLValues if we're called via
12089 // Expr::tryEvaluateObjectSize.
12090 APValue RVal;
12091 if (!EvaluateAsRValue(Info, E, RVal))
12092 return false;
12093 LVal.setFrom(Info.Ctx, RVal);
12094 } else if (!EvaluatePointer(ignorePointerCastsAndParens(E), LVal, Info,
12095 /*InvalidBaseOK=*/true))
12096 return false;
12097 }
12098
12099 // If we point to before the start of the object, there are no accessible
12100 // bytes.
12101 if (LVal.getLValueOffset().isNegative()) {
12102 Size = 0;
12103 return true;
12104 }
12105
12106 CharUnits EndOffset;
12107 if (!determineEndOffset(Info, E->getExprLoc(), Type, LVal, EndOffset))
12108 return false;
12109
12110 // If we've fallen outside of the end offset, just pretend there's nothing to
12111 // write to/read from.
12112 if (EndOffset <= LVal.getLValueOffset())
12113 Size = 0;
12114 else
12115 Size = (EndOffset - LVal.getLValueOffset()).getQuantity();
12116 return true;
12117 }
12118
VisitCallExpr(const CallExpr * E)12119 bool IntExprEvaluator::VisitCallExpr(const CallExpr *E) {
12120 if (!IsConstantEvaluatedBuiltinCall(E))
12121 return ExprEvaluatorBaseTy::VisitCallExpr(E);
12122 return VisitBuiltinCallExpr(E, E->getBuiltinCallee());
12123 }
12124
getBuiltinAlignArguments(const CallExpr * E,EvalInfo & Info,APValue & Val,APSInt & Alignment)12125 static bool getBuiltinAlignArguments(const CallExpr *E, EvalInfo &Info,
12126 APValue &Val, APSInt &Alignment) {
12127 QualType SrcTy = E->getArg(0)->getType();
12128 if (!getAlignmentArgument(E->getArg(1), SrcTy, Info, Alignment))
12129 return false;
12130 // Even though we are evaluating integer expressions we could get a pointer
12131 // argument for the __builtin_is_aligned() case.
12132 if (SrcTy->isPointerType()) {
12133 LValue Ptr;
12134 if (!EvaluatePointer(E->getArg(0), Ptr, Info))
12135 return false;
12136 Ptr.moveInto(Val);
12137 } else if (!SrcTy->isIntegralOrEnumerationType()) {
12138 Info.FFDiag(E->getArg(0));
12139 return false;
12140 } else {
12141 APSInt SrcInt;
12142 if (!EvaluateInteger(E->getArg(0), SrcInt, Info))
12143 return false;
12144 assert(SrcInt.getBitWidth() >= Alignment.getBitWidth() &&
12145 "Bit widths must be the same");
12146 Val = APValue(SrcInt);
12147 }
12148 assert(Val.hasValue());
12149 return true;
12150 }
12151
VisitBuiltinCallExpr(const CallExpr * E,unsigned BuiltinOp)12152 bool IntExprEvaluator::VisitBuiltinCallExpr(const CallExpr *E,
12153 unsigned BuiltinOp) {
12154 switch (BuiltinOp) {
12155 default:
12156 return false;
12157
12158 case Builtin::BI__builtin_dynamic_object_size:
12159 case Builtin::BI__builtin_object_size: {
12160 // The type was checked when we built the expression.
12161 unsigned Type =
12162 E->getArg(1)->EvaluateKnownConstInt(Info.Ctx).getZExtValue();
12163 assert(Type <= 3 && "unexpected type");
12164
12165 uint64_t Size;
12166 if (tryEvaluateBuiltinObjectSize(E->getArg(0), Type, Info, Size))
12167 return Success(Size, E);
12168
12169 if (E->getArg(0)->HasSideEffects(Info.Ctx))
12170 return Success((Type & 2) ? 0 : -1, E);
12171
12172 // Expression had no side effects, but we couldn't statically determine the
12173 // size of the referenced object.
12174 switch (Info.EvalMode) {
12175 case EvalInfo::EM_ConstantExpression:
12176 case EvalInfo::EM_ConstantFold:
12177 case EvalInfo::EM_IgnoreSideEffects:
12178 // Leave it to IR generation.
12179 return Error(E);
12180 case EvalInfo::EM_ConstantExpressionUnevaluated:
12181 // Reduce it to a constant now.
12182 return Success((Type & 2) ? 0 : -1, E);
12183 }
12184
12185 llvm_unreachable("unexpected EvalMode");
12186 }
12187
12188 case Builtin::BI__builtin_os_log_format_buffer_size: {
12189 analyze_os_log::OSLogBufferLayout Layout;
12190 analyze_os_log::computeOSLogBufferLayout(Info.Ctx, E, Layout);
12191 return Success(Layout.size().getQuantity(), E);
12192 }
12193
12194 case Builtin::BI__builtin_is_aligned: {
12195 APValue Src;
12196 APSInt Alignment;
12197 if (!getBuiltinAlignArguments(E, Info, Src, Alignment))
12198 return false;
12199 if (Src.isLValue()) {
12200 // If we evaluated a pointer, check the minimum known alignment.
12201 LValue Ptr;
12202 Ptr.setFrom(Info.Ctx, Src);
12203 CharUnits BaseAlignment = getBaseAlignment(Info, Ptr);
12204 CharUnits PtrAlign = BaseAlignment.alignmentAtOffset(Ptr.Offset);
12205 // We can return true if the known alignment at the computed offset is
12206 // greater than the requested alignment.
12207 assert(PtrAlign.isPowerOfTwo());
12208 assert(Alignment.isPowerOf2());
12209 if (PtrAlign.getQuantity() >= Alignment)
12210 return Success(1, E);
12211 // If the alignment is not known to be sufficient, some cases could still
12212 // be aligned at run time. However, if the requested alignment is less or
12213 // equal to the base alignment and the offset is not aligned, we know that
12214 // the run-time value can never be aligned.
12215 if (BaseAlignment.getQuantity() >= Alignment &&
12216 PtrAlign.getQuantity() < Alignment)
12217 return Success(0, E);
12218 // Otherwise we can't infer whether the value is sufficiently aligned.
12219 // TODO: __builtin_is_aligned(__builtin_align_{down,up{(expr, N), N)
12220 // in cases where we can't fully evaluate the pointer.
12221 Info.FFDiag(E->getArg(0), diag::note_constexpr_alignment_compute)
12222 << Alignment;
12223 return false;
12224 }
12225 assert(Src.isInt());
12226 return Success((Src.getInt() & (Alignment - 1)) == 0 ? 1 : 0, E);
12227 }
12228 case Builtin::BI__builtin_align_up: {
12229 APValue Src;
12230 APSInt Alignment;
12231 if (!getBuiltinAlignArguments(E, Info, Src, Alignment))
12232 return false;
12233 if (!Src.isInt())
12234 return Error(E);
12235 APSInt AlignedVal =
12236 APSInt((Src.getInt() + (Alignment - 1)) & ~(Alignment - 1),
12237 Src.getInt().isUnsigned());
12238 assert(AlignedVal.getBitWidth() == Src.getInt().getBitWidth());
12239 return Success(AlignedVal, E);
12240 }
12241 case Builtin::BI__builtin_align_down: {
12242 APValue Src;
12243 APSInt Alignment;
12244 if (!getBuiltinAlignArguments(E, Info, Src, Alignment))
12245 return false;
12246 if (!Src.isInt())
12247 return Error(E);
12248 APSInt AlignedVal =
12249 APSInt(Src.getInt() & ~(Alignment - 1), Src.getInt().isUnsigned());
12250 assert(AlignedVal.getBitWidth() == Src.getInt().getBitWidth());
12251 return Success(AlignedVal, E);
12252 }
12253
12254 case Builtin::BI__builtin_bitreverse8:
12255 case Builtin::BI__builtin_bitreverse16:
12256 case Builtin::BI__builtin_bitreverse32:
12257 case Builtin::BI__builtin_bitreverse64: {
12258 APSInt Val;
12259 if (!EvaluateInteger(E->getArg(0), Val, Info))
12260 return false;
12261
12262 return Success(Val.reverseBits(), E);
12263 }
12264
12265 case Builtin::BI__builtin_bswap16:
12266 case Builtin::BI__builtin_bswap32:
12267 case Builtin::BI__builtin_bswap64: {
12268 APSInt Val;
12269 if (!EvaluateInteger(E->getArg(0), Val, Info))
12270 return false;
12271
12272 return Success(Val.byteSwap(), E);
12273 }
12274
12275 case Builtin::BI__builtin_classify_type:
12276 return Success((int)EvaluateBuiltinClassifyType(E, Info.getLangOpts()), E);
12277
12278 case Builtin::BI__builtin_clrsb:
12279 case Builtin::BI__builtin_clrsbl:
12280 case Builtin::BI__builtin_clrsbll: {
12281 APSInt Val;
12282 if (!EvaluateInteger(E->getArg(0), Val, Info))
12283 return false;
12284
12285 return Success(Val.getBitWidth() - Val.getSignificantBits(), E);
12286 }
12287
12288 case Builtin::BI__builtin_clz:
12289 case Builtin::BI__builtin_clzl:
12290 case Builtin::BI__builtin_clzll:
12291 case Builtin::BI__builtin_clzs:
12292 case Builtin::BI__lzcnt16: // Microsoft variants of count leading-zeroes
12293 case Builtin::BI__lzcnt:
12294 case Builtin::BI__lzcnt64: {
12295 APSInt Val;
12296 if (!EvaluateInteger(E->getArg(0), Val, Info))
12297 return false;
12298
12299 // When the argument is 0, the result of GCC builtins is undefined, whereas
12300 // for Microsoft intrinsics, the result is the bit-width of the argument.
12301 bool ZeroIsUndefined = BuiltinOp != Builtin::BI__lzcnt16 &&
12302 BuiltinOp != Builtin::BI__lzcnt &&
12303 BuiltinOp != Builtin::BI__lzcnt64;
12304
12305 if (ZeroIsUndefined && !Val)
12306 return Error(E);
12307
12308 return Success(Val.countl_zero(), E);
12309 }
12310
12311 case Builtin::BI__builtin_constant_p: {
12312 const Expr *Arg = E->getArg(0);
12313 if (EvaluateBuiltinConstantP(Info, Arg))
12314 return Success(true, E);
12315 if (Info.InConstantContext || Arg->HasSideEffects(Info.Ctx)) {
12316 // Outside a constant context, eagerly evaluate to false in the presence
12317 // of side-effects in order to avoid -Wunsequenced false-positives in
12318 // a branch on __builtin_constant_p(expr).
12319 return Success(false, E);
12320 }
12321 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
12322 return false;
12323 }
12324
12325 case Builtin::BI__builtin_is_constant_evaluated: {
12326 const auto *Callee = Info.CurrentCall->getCallee();
12327 if (Info.InConstantContext && !Info.CheckingPotentialConstantExpression &&
12328 (Info.CallStackDepth == 1 ||
12329 (Info.CallStackDepth == 2 && Callee->isInStdNamespace() &&
12330 Callee->getIdentifier() &&
12331 Callee->getIdentifier()->isStr("is_constant_evaluated")))) {
12332 // FIXME: Find a better way to avoid duplicated diagnostics.
12333 if (Info.EvalStatus.Diag)
12334 Info.report((Info.CallStackDepth == 1)
12335 ? E->getExprLoc()
12336 : Info.CurrentCall->getCallRange().getBegin(),
12337 diag::warn_is_constant_evaluated_always_true_constexpr)
12338 << (Info.CallStackDepth == 1 ? "__builtin_is_constant_evaluated"
12339 : "std::is_constant_evaluated");
12340 }
12341
12342 return Success(Info.InConstantContext, E);
12343 }
12344
12345 case Builtin::BI__builtin_ctz:
12346 case Builtin::BI__builtin_ctzl:
12347 case Builtin::BI__builtin_ctzll:
12348 case Builtin::BI__builtin_ctzs: {
12349 APSInt Val;
12350 if (!EvaluateInteger(E->getArg(0), Val, Info))
12351 return false;
12352 if (!Val)
12353 return Error(E);
12354
12355 return Success(Val.countr_zero(), E);
12356 }
12357
12358 case Builtin::BI__builtin_eh_return_data_regno: {
12359 int Operand = E->getArg(0)->EvaluateKnownConstInt(Info.Ctx).getZExtValue();
12360 Operand = Info.Ctx.getTargetInfo().getEHDataRegisterNumber(Operand);
12361 return Success(Operand, E);
12362 }
12363
12364 case Builtin::BI__builtin_expect:
12365 case Builtin::BI__builtin_expect_with_probability:
12366 return Visit(E->getArg(0));
12367
12368 case Builtin::BI__builtin_ffs:
12369 case Builtin::BI__builtin_ffsl:
12370 case Builtin::BI__builtin_ffsll: {
12371 APSInt Val;
12372 if (!EvaluateInteger(E->getArg(0), Val, Info))
12373 return false;
12374
12375 unsigned N = Val.countr_zero();
12376 return Success(N == Val.getBitWidth() ? 0 : N + 1, E);
12377 }
12378
12379 case Builtin::BI__builtin_fpclassify: {
12380 APFloat Val(0.0);
12381 if (!EvaluateFloat(E->getArg(5), Val, Info))
12382 return false;
12383 unsigned Arg;
12384 switch (Val.getCategory()) {
12385 case APFloat::fcNaN: Arg = 0; break;
12386 case APFloat::fcInfinity: Arg = 1; break;
12387 case APFloat::fcNormal: Arg = Val.isDenormal() ? 3 : 2; break;
12388 case APFloat::fcZero: Arg = 4; break;
12389 }
12390 return Visit(E->getArg(Arg));
12391 }
12392
12393 case Builtin::BI__builtin_isinf_sign: {
12394 APFloat Val(0.0);
12395 return EvaluateFloat(E->getArg(0), Val, Info) &&
12396 Success(Val.isInfinity() ? (Val.isNegative() ? -1 : 1) : 0, E);
12397 }
12398
12399 case Builtin::BI__builtin_isinf: {
12400 APFloat Val(0.0);
12401 return EvaluateFloat(E->getArg(0), Val, Info) &&
12402 Success(Val.isInfinity() ? 1 : 0, E);
12403 }
12404
12405 case Builtin::BI__builtin_isfinite: {
12406 APFloat Val(0.0);
12407 return EvaluateFloat(E->getArg(0), Val, Info) &&
12408 Success(Val.isFinite() ? 1 : 0, E);
12409 }
12410
12411 case Builtin::BI__builtin_isnan: {
12412 APFloat Val(0.0);
12413 return EvaluateFloat(E->getArg(0), Val, Info) &&
12414 Success(Val.isNaN() ? 1 : 0, E);
12415 }
12416
12417 case Builtin::BI__builtin_isnormal: {
12418 APFloat Val(0.0);
12419 return EvaluateFloat(E->getArg(0), Val, Info) &&
12420 Success(Val.isNormal() ? 1 : 0, E);
12421 }
12422
12423 case Builtin::BI__builtin_issubnormal: {
12424 APFloat Val(0.0);
12425 return EvaluateFloat(E->getArg(0), Val, Info) &&
12426 Success(Val.isDenormal() ? 1 : 0, E);
12427 }
12428
12429 case Builtin::BI__builtin_iszero: {
12430 APFloat Val(0.0);
12431 return EvaluateFloat(E->getArg(0), Val, Info) &&
12432 Success(Val.isZero() ? 1 : 0, E);
12433 }
12434
12435 case Builtin::BI__builtin_issignaling: {
12436 APFloat Val(0.0);
12437 return EvaluateFloat(E->getArg(0), Val, Info) &&
12438 Success(Val.isSignaling() ? 1 : 0, E);
12439 }
12440
12441 case Builtin::BI__builtin_isfpclass: {
12442 APSInt MaskVal;
12443 if (!EvaluateInteger(E->getArg(1), MaskVal, Info))
12444 return false;
12445 unsigned Test = static_cast<llvm::FPClassTest>(MaskVal.getZExtValue());
12446 APFloat Val(0.0);
12447 return EvaluateFloat(E->getArg(0), Val, Info) &&
12448 Success((Val.classify() & Test) ? 1 : 0, E);
12449 }
12450
12451 case Builtin::BI__builtin_parity:
12452 case Builtin::BI__builtin_parityl:
12453 case Builtin::BI__builtin_parityll: {
12454 APSInt Val;
12455 if (!EvaluateInteger(E->getArg(0), Val, Info))
12456 return false;
12457
12458 return Success(Val.popcount() % 2, E);
12459 }
12460
12461 case Builtin::BI__builtin_popcount:
12462 case Builtin::BI__builtin_popcountl:
12463 case Builtin::BI__builtin_popcountll:
12464 case Builtin::BI__popcnt16: // Microsoft variants of popcount
12465 case Builtin::BI__popcnt:
12466 case Builtin::BI__popcnt64: {
12467 APSInt Val;
12468 if (!EvaluateInteger(E->getArg(0), Val, Info))
12469 return false;
12470
12471 return Success(Val.popcount(), E);
12472 }
12473
12474 case Builtin::BI__builtin_rotateleft8:
12475 case Builtin::BI__builtin_rotateleft16:
12476 case Builtin::BI__builtin_rotateleft32:
12477 case Builtin::BI__builtin_rotateleft64:
12478 case Builtin::BI_rotl8: // Microsoft variants of rotate right
12479 case Builtin::BI_rotl16:
12480 case Builtin::BI_rotl:
12481 case Builtin::BI_lrotl:
12482 case Builtin::BI_rotl64: {
12483 APSInt Val, Amt;
12484 if (!EvaluateInteger(E->getArg(0), Val, Info) ||
12485 !EvaluateInteger(E->getArg(1), Amt, Info))
12486 return false;
12487
12488 return Success(Val.rotl(Amt.urem(Val.getBitWidth())), E);
12489 }
12490
12491 case Builtin::BI__builtin_rotateright8:
12492 case Builtin::BI__builtin_rotateright16:
12493 case Builtin::BI__builtin_rotateright32:
12494 case Builtin::BI__builtin_rotateright64:
12495 case Builtin::BI_rotr8: // Microsoft variants of rotate right
12496 case Builtin::BI_rotr16:
12497 case Builtin::BI_rotr:
12498 case Builtin::BI_lrotr:
12499 case Builtin::BI_rotr64: {
12500 APSInt Val, Amt;
12501 if (!EvaluateInteger(E->getArg(0), Val, Info) ||
12502 !EvaluateInteger(E->getArg(1), Amt, Info))
12503 return false;
12504
12505 return Success(Val.rotr(Amt.urem(Val.getBitWidth())), E);
12506 }
12507
12508 case Builtin::BIstrlen:
12509 case Builtin::BIwcslen:
12510 // A call to strlen is not a constant expression.
12511 if (Info.getLangOpts().CPlusPlus11)
12512 Info.CCEDiag(E, diag::note_constexpr_invalid_function)
12513 << /*isConstexpr*/ 0 << /*isConstructor*/ 0
12514 << ("'" + Info.Ctx.BuiltinInfo.getName(BuiltinOp) + "'").str();
12515 else
12516 Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr);
12517 [[fallthrough]];
12518 case Builtin::BI__builtin_strlen:
12519 case Builtin::BI__builtin_wcslen: {
12520 // As an extension, we support __builtin_strlen() as a constant expression,
12521 // and support folding strlen() to a constant.
12522 uint64_t StrLen;
12523 if (EvaluateBuiltinStrLen(E->getArg(0), StrLen, Info))
12524 return Success(StrLen, E);
12525 return false;
12526 }
12527
12528 case Builtin::BIstrcmp:
12529 case Builtin::BIwcscmp:
12530 case Builtin::BIstrncmp:
12531 case Builtin::BIwcsncmp:
12532 case Builtin::BImemcmp:
12533 case Builtin::BIbcmp:
12534 case Builtin::BIwmemcmp:
12535 // A call to strlen is not a constant expression.
12536 if (Info.getLangOpts().CPlusPlus11)
12537 Info.CCEDiag(E, diag::note_constexpr_invalid_function)
12538 << /*isConstexpr*/ 0 << /*isConstructor*/ 0
12539 << ("'" + Info.Ctx.BuiltinInfo.getName(BuiltinOp) + "'").str();
12540 else
12541 Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr);
12542 [[fallthrough]];
12543 case Builtin::BI__builtin_strcmp:
12544 case Builtin::BI__builtin_wcscmp:
12545 case Builtin::BI__builtin_strncmp:
12546 case Builtin::BI__builtin_wcsncmp:
12547 case Builtin::BI__builtin_memcmp:
12548 case Builtin::BI__builtin_bcmp:
12549 case Builtin::BI__builtin_wmemcmp: {
12550 LValue String1, String2;
12551 if (!EvaluatePointer(E->getArg(0), String1, Info) ||
12552 !EvaluatePointer(E->getArg(1), String2, Info))
12553 return false;
12554
12555 uint64_t MaxLength = uint64_t(-1);
12556 if (BuiltinOp != Builtin::BIstrcmp &&
12557 BuiltinOp != Builtin::BIwcscmp &&
12558 BuiltinOp != Builtin::BI__builtin_strcmp &&
12559 BuiltinOp != Builtin::BI__builtin_wcscmp) {
12560 APSInt N;
12561 if (!EvaluateInteger(E->getArg(2), N, Info))
12562 return false;
12563 MaxLength = N.getZExtValue();
12564 }
12565
12566 // Empty substrings compare equal by definition.
12567 if (MaxLength == 0u)
12568 return Success(0, E);
12569
12570 if (!String1.checkNullPointerForFoldAccess(Info, E, AK_Read) ||
12571 !String2.checkNullPointerForFoldAccess(Info, E, AK_Read) ||
12572 String1.Designator.Invalid || String2.Designator.Invalid)
12573 return false;
12574
12575 QualType CharTy1 = String1.Designator.getType(Info.Ctx);
12576 QualType CharTy2 = String2.Designator.getType(Info.Ctx);
12577
12578 bool IsRawByte = BuiltinOp == Builtin::BImemcmp ||
12579 BuiltinOp == Builtin::BIbcmp ||
12580 BuiltinOp == Builtin::BI__builtin_memcmp ||
12581 BuiltinOp == Builtin::BI__builtin_bcmp;
12582
12583 assert(IsRawByte ||
12584 (Info.Ctx.hasSameUnqualifiedType(
12585 CharTy1, E->getArg(0)->getType()->getPointeeType()) &&
12586 Info.Ctx.hasSameUnqualifiedType(CharTy1, CharTy2)));
12587
12588 // For memcmp, allow comparing any arrays of '[[un]signed] char' or
12589 // 'char8_t', but no other types.
12590 if (IsRawByte &&
12591 !(isOneByteCharacterType(CharTy1) && isOneByteCharacterType(CharTy2))) {
12592 // FIXME: Consider using our bit_cast implementation to support this.
12593 Info.FFDiag(E, diag::note_constexpr_memcmp_unsupported)
12594 << ("'" + Info.Ctx.BuiltinInfo.getName(BuiltinOp) + "'").str()
12595 << CharTy1 << CharTy2;
12596 return false;
12597 }
12598
12599 const auto &ReadCurElems = [&](APValue &Char1, APValue &Char2) {
12600 return handleLValueToRValueConversion(Info, E, CharTy1, String1, Char1) &&
12601 handleLValueToRValueConversion(Info, E, CharTy2, String2, Char2) &&
12602 Char1.isInt() && Char2.isInt();
12603 };
12604 const auto &AdvanceElems = [&] {
12605 return HandleLValueArrayAdjustment(Info, E, String1, CharTy1, 1) &&
12606 HandleLValueArrayAdjustment(Info, E, String2, CharTy2, 1);
12607 };
12608
12609 bool StopAtNull =
12610 (BuiltinOp != Builtin::BImemcmp && BuiltinOp != Builtin::BIbcmp &&
12611 BuiltinOp != Builtin::BIwmemcmp &&
12612 BuiltinOp != Builtin::BI__builtin_memcmp &&
12613 BuiltinOp != Builtin::BI__builtin_bcmp &&
12614 BuiltinOp != Builtin::BI__builtin_wmemcmp);
12615 bool IsWide = BuiltinOp == Builtin::BIwcscmp ||
12616 BuiltinOp == Builtin::BIwcsncmp ||
12617 BuiltinOp == Builtin::BIwmemcmp ||
12618 BuiltinOp == Builtin::BI__builtin_wcscmp ||
12619 BuiltinOp == Builtin::BI__builtin_wcsncmp ||
12620 BuiltinOp == Builtin::BI__builtin_wmemcmp;
12621
12622 for (; MaxLength; --MaxLength) {
12623 APValue Char1, Char2;
12624 if (!ReadCurElems(Char1, Char2))
12625 return false;
12626 if (Char1.getInt().ne(Char2.getInt())) {
12627 if (IsWide) // wmemcmp compares with wchar_t signedness.
12628 return Success(Char1.getInt() < Char2.getInt() ? -1 : 1, E);
12629 // memcmp always compares unsigned chars.
12630 return Success(Char1.getInt().ult(Char2.getInt()) ? -1 : 1, E);
12631 }
12632 if (StopAtNull && !Char1.getInt())
12633 return Success(0, E);
12634 assert(!(StopAtNull && !Char2.getInt()));
12635 if (!AdvanceElems())
12636 return false;
12637 }
12638 // We hit the strncmp / memcmp limit.
12639 return Success(0, E);
12640 }
12641
12642 case Builtin::BI__atomic_always_lock_free:
12643 case Builtin::BI__atomic_is_lock_free:
12644 case Builtin::BI__c11_atomic_is_lock_free: {
12645 APSInt SizeVal;
12646 if (!EvaluateInteger(E->getArg(0), SizeVal, Info))
12647 return false;
12648
12649 // For __atomic_is_lock_free(sizeof(_Atomic(T))), if the size is a power
12650 // of two less than or equal to the maximum inline atomic width, we know it
12651 // is lock-free. If the size isn't a power of two, or greater than the
12652 // maximum alignment where we promote atomics, we know it is not lock-free
12653 // (at least not in the sense of atomic_is_lock_free). Otherwise,
12654 // the answer can only be determined at runtime; for example, 16-byte
12655 // atomics have lock-free implementations on some, but not all,
12656 // x86-64 processors.
12657
12658 // Check power-of-two.
12659 CharUnits Size = CharUnits::fromQuantity(SizeVal.getZExtValue());
12660 if (Size.isPowerOfTwo()) {
12661 // Check against inlining width.
12662 unsigned InlineWidthBits =
12663 Info.Ctx.getTargetInfo().getMaxAtomicInlineWidth();
12664 if (Size <= Info.Ctx.toCharUnitsFromBits(InlineWidthBits)) {
12665 if (BuiltinOp == Builtin::BI__c11_atomic_is_lock_free ||
12666 Size == CharUnits::One() ||
12667 E->getArg(1)->isNullPointerConstant(Info.Ctx,
12668 Expr::NPC_NeverValueDependent))
12669 // OK, we will inline appropriately-aligned operations of this size,
12670 // and _Atomic(T) is appropriately-aligned.
12671 return Success(1, E);
12672
12673 QualType PointeeType = E->getArg(1)->IgnoreImpCasts()->getType()->
12674 castAs<PointerType>()->getPointeeType();
12675 if (!PointeeType->isIncompleteType() &&
12676 Info.Ctx.getTypeAlignInChars(PointeeType) >= Size) {
12677 // OK, we will inline operations on this object.
12678 return Success(1, E);
12679 }
12680 }
12681 }
12682
12683 return BuiltinOp == Builtin::BI__atomic_always_lock_free ?
12684 Success(0, E) : Error(E);
12685 }
12686 case Builtin::BI__builtin_add_overflow:
12687 case Builtin::BI__builtin_sub_overflow:
12688 case Builtin::BI__builtin_mul_overflow:
12689 case Builtin::BI__builtin_sadd_overflow:
12690 case Builtin::BI__builtin_uadd_overflow:
12691 case Builtin::BI__builtin_uaddl_overflow:
12692 case Builtin::BI__builtin_uaddll_overflow:
12693 case Builtin::BI__builtin_usub_overflow:
12694 case Builtin::BI__builtin_usubl_overflow:
12695 case Builtin::BI__builtin_usubll_overflow:
12696 case Builtin::BI__builtin_umul_overflow:
12697 case Builtin::BI__builtin_umull_overflow:
12698 case Builtin::BI__builtin_umulll_overflow:
12699 case Builtin::BI__builtin_saddl_overflow:
12700 case Builtin::BI__builtin_saddll_overflow:
12701 case Builtin::BI__builtin_ssub_overflow:
12702 case Builtin::BI__builtin_ssubl_overflow:
12703 case Builtin::BI__builtin_ssubll_overflow:
12704 case Builtin::BI__builtin_smul_overflow:
12705 case Builtin::BI__builtin_smull_overflow:
12706 case Builtin::BI__builtin_smulll_overflow: {
12707 LValue ResultLValue;
12708 APSInt LHS, RHS;
12709
12710 QualType ResultType = E->getArg(2)->getType()->getPointeeType();
12711 if (!EvaluateInteger(E->getArg(0), LHS, Info) ||
12712 !EvaluateInteger(E->getArg(1), RHS, Info) ||
12713 !EvaluatePointer(E->getArg(2), ResultLValue, Info))
12714 return false;
12715
12716 APSInt Result;
12717 bool DidOverflow = false;
12718
12719 // If the types don't have to match, enlarge all 3 to the largest of them.
12720 if (BuiltinOp == Builtin::BI__builtin_add_overflow ||
12721 BuiltinOp == Builtin::BI__builtin_sub_overflow ||
12722 BuiltinOp == Builtin::BI__builtin_mul_overflow) {
12723 bool IsSigned = LHS.isSigned() || RHS.isSigned() ||
12724 ResultType->isSignedIntegerOrEnumerationType();
12725 bool AllSigned = LHS.isSigned() && RHS.isSigned() &&
12726 ResultType->isSignedIntegerOrEnumerationType();
12727 uint64_t LHSSize = LHS.getBitWidth();
12728 uint64_t RHSSize = RHS.getBitWidth();
12729 uint64_t ResultSize = Info.Ctx.getTypeSize(ResultType);
12730 uint64_t MaxBits = std::max(std::max(LHSSize, RHSSize), ResultSize);
12731
12732 // Add an additional bit if the signedness isn't uniformly agreed to. We
12733 // could do this ONLY if there is a signed and an unsigned that both have
12734 // MaxBits, but the code to check that is pretty nasty. The issue will be
12735 // caught in the shrink-to-result later anyway.
12736 if (IsSigned && !AllSigned)
12737 ++MaxBits;
12738
12739 LHS = APSInt(LHS.extOrTrunc(MaxBits), !IsSigned);
12740 RHS = APSInt(RHS.extOrTrunc(MaxBits), !IsSigned);
12741 Result = APSInt(MaxBits, !IsSigned);
12742 }
12743
12744 // Find largest int.
12745 switch (BuiltinOp) {
12746 default:
12747 llvm_unreachable("Invalid value for BuiltinOp");
12748 case Builtin::BI__builtin_add_overflow:
12749 case Builtin::BI__builtin_sadd_overflow:
12750 case Builtin::BI__builtin_saddl_overflow:
12751 case Builtin::BI__builtin_saddll_overflow:
12752 case Builtin::BI__builtin_uadd_overflow:
12753 case Builtin::BI__builtin_uaddl_overflow:
12754 case Builtin::BI__builtin_uaddll_overflow:
12755 Result = LHS.isSigned() ? LHS.sadd_ov(RHS, DidOverflow)
12756 : LHS.uadd_ov(RHS, DidOverflow);
12757 break;
12758 case Builtin::BI__builtin_sub_overflow:
12759 case Builtin::BI__builtin_ssub_overflow:
12760 case Builtin::BI__builtin_ssubl_overflow:
12761 case Builtin::BI__builtin_ssubll_overflow:
12762 case Builtin::BI__builtin_usub_overflow:
12763 case Builtin::BI__builtin_usubl_overflow:
12764 case Builtin::BI__builtin_usubll_overflow:
12765 Result = LHS.isSigned() ? LHS.ssub_ov(RHS, DidOverflow)
12766 : LHS.usub_ov(RHS, DidOverflow);
12767 break;
12768 case Builtin::BI__builtin_mul_overflow:
12769 case Builtin::BI__builtin_smul_overflow:
12770 case Builtin::BI__builtin_smull_overflow:
12771 case Builtin::BI__builtin_smulll_overflow:
12772 case Builtin::BI__builtin_umul_overflow:
12773 case Builtin::BI__builtin_umull_overflow:
12774 case Builtin::BI__builtin_umulll_overflow:
12775 Result = LHS.isSigned() ? LHS.smul_ov(RHS, DidOverflow)
12776 : LHS.umul_ov(RHS, DidOverflow);
12777 break;
12778 }
12779
12780 // In the case where multiple sizes are allowed, truncate and see if
12781 // the values are the same.
12782 if (BuiltinOp == Builtin::BI__builtin_add_overflow ||
12783 BuiltinOp == Builtin::BI__builtin_sub_overflow ||
12784 BuiltinOp == Builtin::BI__builtin_mul_overflow) {
12785 // APSInt doesn't have a TruncOrSelf, so we use extOrTrunc instead,
12786 // since it will give us the behavior of a TruncOrSelf in the case where
12787 // its parameter <= its size. We previously set Result to be at least the
12788 // type-size of the result, so getTypeSize(ResultType) <= Result.BitWidth
12789 // will work exactly like TruncOrSelf.
12790 APSInt Temp = Result.extOrTrunc(Info.Ctx.getTypeSize(ResultType));
12791 Temp.setIsSigned(ResultType->isSignedIntegerOrEnumerationType());
12792
12793 if (!APSInt::isSameValue(Temp, Result))
12794 DidOverflow = true;
12795 Result = Temp;
12796 }
12797
12798 APValue APV{Result};
12799 if (!handleAssignment(Info, E, ResultLValue, ResultType, APV))
12800 return false;
12801 return Success(DidOverflow, E);
12802 }
12803 }
12804 }
12805
12806 /// Determine whether this is a pointer past the end of the complete
12807 /// object referred to by the lvalue.
isOnePastTheEndOfCompleteObject(const ASTContext & Ctx,const LValue & LV)12808 static bool isOnePastTheEndOfCompleteObject(const ASTContext &Ctx,
12809 const LValue &LV) {
12810 // A null pointer can be viewed as being "past the end" but we don't
12811 // choose to look at it that way here.
12812 if (!LV.getLValueBase())
12813 return false;
12814
12815 // If the designator is valid and refers to a subobject, we're not pointing
12816 // past the end.
12817 if (!LV.getLValueDesignator().Invalid &&
12818 !LV.getLValueDesignator().isOnePastTheEnd())
12819 return false;
12820
12821 // A pointer to an incomplete type might be past-the-end if the type's size is
12822 // zero. We cannot tell because the type is incomplete.
12823 QualType Ty = getType(LV.getLValueBase());
12824 if (Ty->isIncompleteType())
12825 return true;
12826
12827 // We're a past-the-end pointer if we point to the byte after the object,
12828 // no matter what our type or path is.
12829 auto Size = Ctx.getTypeSizeInChars(Ty);
12830 return LV.getLValueOffset() == Size;
12831 }
12832
12833 namespace {
12834
12835 /// Data recursive integer evaluator of certain binary operators.
12836 ///
12837 /// We use a data recursive algorithm for binary operators so that we are able
12838 /// to handle extreme cases of chained binary operators without causing stack
12839 /// overflow.
12840 class DataRecursiveIntBinOpEvaluator {
12841 struct EvalResult {
12842 APValue Val;
12843 bool Failed = false;
12844
12845 EvalResult() = default;
12846
swap__anonbf0ddd822a11::DataRecursiveIntBinOpEvaluator::EvalResult12847 void swap(EvalResult &RHS) {
12848 Val.swap(RHS.Val);
12849 Failed = RHS.Failed;
12850 RHS.Failed = false;
12851 }
12852 };
12853
12854 struct Job {
12855 const Expr *E;
12856 EvalResult LHSResult; // meaningful only for binary operator expression.
12857 enum { AnyExprKind, BinOpKind, BinOpVisitedLHSKind } Kind;
12858
12859 Job() = default;
12860 Job(Job &&) = default;
12861
startSpeculativeEval__anonbf0ddd822a11::DataRecursiveIntBinOpEvaluator::Job12862 void startSpeculativeEval(EvalInfo &Info) {
12863 SpecEvalRAII = SpeculativeEvaluationRAII(Info);
12864 }
12865
12866 private:
12867 SpeculativeEvaluationRAII SpecEvalRAII;
12868 };
12869
12870 SmallVector<Job, 16> Queue;
12871
12872 IntExprEvaluator &IntEval;
12873 EvalInfo &Info;
12874 APValue &FinalResult;
12875
12876 public:
DataRecursiveIntBinOpEvaluator(IntExprEvaluator & IntEval,APValue & Result)12877 DataRecursiveIntBinOpEvaluator(IntExprEvaluator &IntEval, APValue &Result)
12878 : IntEval(IntEval), Info(IntEval.getEvalInfo()), FinalResult(Result) { }
12879
12880 /// True if \param E is a binary operator that we are going to handle
12881 /// data recursively.
12882 /// We handle binary operators that are comma, logical, or that have operands
12883 /// with integral or enumeration type.
shouldEnqueue(const BinaryOperator * E)12884 static bool shouldEnqueue(const BinaryOperator *E) {
12885 return E->getOpcode() == BO_Comma || E->isLogicalOp() ||
12886 (E->isPRValue() && E->getType()->isIntegralOrEnumerationType() &&
12887 E->getLHS()->getType()->isIntegralOrEnumerationType() &&
12888 E->getRHS()->getType()->isIntegralOrEnumerationType());
12889 }
12890
Traverse(const BinaryOperator * E)12891 bool Traverse(const BinaryOperator *E) {
12892 enqueue(E);
12893 EvalResult PrevResult;
12894 while (!Queue.empty())
12895 process(PrevResult);
12896
12897 if (PrevResult.Failed) return false;
12898
12899 FinalResult.swap(PrevResult.Val);
12900 return true;
12901 }
12902
12903 private:
Success(uint64_t Value,const Expr * E,APValue & Result)12904 bool Success(uint64_t Value, const Expr *E, APValue &Result) {
12905 return IntEval.Success(Value, E, Result);
12906 }
Success(const APSInt & Value,const Expr * E,APValue & Result)12907 bool Success(const APSInt &Value, const Expr *E, APValue &Result) {
12908 return IntEval.Success(Value, E, Result);
12909 }
Error(const Expr * E)12910 bool Error(const Expr *E) {
12911 return IntEval.Error(E);
12912 }
Error(const Expr * E,diag::kind D)12913 bool Error(const Expr *E, diag::kind D) {
12914 return IntEval.Error(E, D);
12915 }
12916
CCEDiag(const Expr * E,diag::kind D)12917 OptionalDiagnostic CCEDiag(const Expr *E, diag::kind D) {
12918 return Info.CCEDiag(E, D);
12919 }
12920
12921 // Returns true if visiting the RHS is necessary, false otherwise.
12922 bool VisitBinOpLHSOnly(EvalResult &LHSResult, const BinaryOperator *E,
12923 bool &SuppressRHSDiags);
12924
12925 bool VisitBinOp(const EvalResult &LHSResult, const EvalResult &RHSResult,
12926 const BinaryOperator *E, APValue &Result);
12927
EvaluateExpr(const Expr * E,EvalResult & Result)12928 void EvaluateExpr(const Expr *E, EvalResult &Result) {
12929 Result.Failed = !Evaluate(Result.Val, Info, E);
12930 if (Result.Failed)
12931 Result.Val = APValue();
12932 }
12933
12934 void process(EvalResult &Result);
12935
enqueue(const Expr * E)12936 void enqueue(const Expr *E) {
12937 E = E->IgnoreParens();
12938 Queue.resize(Queue.size()+1);
12939 Queue.back().E = E;
12940 Queue.back().Kind = Job::AnyExprKind;
12941 }
12942 };
12943
12944 }
12945
12946 bool DataRecursiveIntBinOpEvaluator::
VisitBinOpLHSOnly(EvalResult & LHSResult,const BinaryOperator * E,bool & SuppressRHSDiags)12947 VisitBinOpLHSOnly(EvalResult &LHSResult, const BinaryOperator *E,
12948 bool &SuppressRHSDiags) {
12949 if (E->getOpcode() == BO_Comma) {
12950 // Ignore LHS but note if we could not evaluate it.
12951 if (LHSResult.Failed)
12952 return Info.noteSideEffect();
12953 return true;
12954 }
12955
12956 if (E->isLogicalOp()) {
12957 bool LHSAsBool;
12958 if (!LHSResult.Failed && HandleConversionToBool(LHSResult.Val, LHSAsBool)) {
12959 // We were able to evaluate the LHS, see if we can get away with not
12960 // evaluating the RHS: 0 && X -> 0, 1 || X -> 1
12961 if (LHSAsBool == (E->getOpcode() == BO_LOr)) {
12962 Success(LHSAsBool, E, LHSResult.Val);
12963 return false; // Ignore RHS
12964 }
12965 } else {
12966 LHSResult.Failed = true;
12967
12968 // Since we weren't able to evaluate the left hand side, it
12969 // might have had side effects.
12970 if (!Info.noteSideEffect())
12971 return false;
12972
12973 // We can't evaluate the LHS; however, sometimes the result
12974 // is determined by the RHS: X && 0 -> 0, X || 1 -> 1.
12975 // Don't ignore RHS and suppress diagnostics from this arm.
12976 SuppressRHSDiags = true;
12977 }
12978
12979 return true;
12980 }
12981
12982 assert(E->getLHS()->getType()->isIntegralOrEnumerationType() &&
12983 E->getRHS()->getType()->isIntegralOrEnumerationType());
12984
12985 if (LHSResult.Failed && !Info.noteFailure())
12986 return false; // Ignore RHS;
12987
12988 return true;
12989 }
12990
addOrSubLValueAsInteger(APValue & LVal,const APSInt & Index,bool IsSub)12991 static void addOrSubLValueAsInteger(APValue &LVal, const APSInt &Index,
12992 bool IsSub) {
12993 // Compute the new offset in the appropriate width, wrapping at 64 bits.
12994 // FIXME: When compiling for a 32-bit target, we should use 32-bit
12995 // offsets.
12996 assert(!LVal.hasLValuePath() && "have designator for integer lvalue");
12997 CharUnits &Offset = LVal.getLValueOffset();
12998 uint64_t Offset64 = Offset.getQuantity();
12999 uint64_t Index64 = Index.extOrTrunc(64).getZExtValue();
13000 Offset = CharUnits::fromQuantity(IsSub ? Offset64 - Index64
13001 : Offset64 + Index64);
13002 }
13003
13004 bool DataRecursiveIntBinOpEvaluator::
VisitBinOp(const EvalResult & LHSResult,const EvalResult & RHSResult,const BinaryOperator * E,APValue & Result)13005 VisitBinOp(const EvalResult &LHSResult, const EvalResult &RHSResult,
13006 const BinaryOperator *E, APValue &Result) {
13007 if (E->getOpcode() == BO_Comma) {
13008 if (RHSResult.Failed)
13009 return false;
13010 Result = RHSResult.Val;
13011 return true;
13012 }
13013
13014 if (E->isLogicalOp()) {
13015 bool lhsResult, rhsResult;
13016 bool LHSIsOK = HandleConversionToBool(LHSResult.Val, lhsResult);
13017 bool RHSIsOK = HandleConversionToBool(RHSResult.Val, rhsResult);
13018
13019 if (LHSIsOK) {
13020 if (RHSIsOK) {
13021 if (E->getOpcode() == BO_LOr)
13022 return Success(lhsResult || rhsResult, E, Result);
13023 else
13024 return Success(lhsResult && rhsResult, E, Result);
13025 }
13026 } else {
13027 if (RHSIsOK) {
13028 // We can't evaluate the LHS; however, sometimes the result
13029 // is determined by the RHS: X && 0 -> 0, X || 1 -> 1.
13030 if (rhsResult == (E->getOpcode() == BO_LOr))
13031 return Success(rhsResult, E, Result);
13032 }
13033 }
13034
13035 return false;
13036 }
13037
13038 assert(E->getLHS()->getType()->isIntegralOrEnumerationType() &&
13039 E->getRHS()->getType()->isIntegralOrEnumerationType());
13040
13041 if (LHSResult.Failed || RHSResult.Failed)
13042 return false;
13043
13044 const APValue &LHSVal = LHSResult.Val;
13045 const APValue &RHSVal = RHSResult.Val;
13046
13047 // Handle cases like (unsigned long)&a + 4.
13048 if (E->isAdditiveOp() && LHSVal.isLValue() && RHSVal.isInt()) {
13049 Result = LHSVal;
13050 addOrSubLValueAsInteger(Result, RHSVal.getInt(), E->getOpcode() == BO_Sub);
13051 return true;
13052 }
13053
13054 // Handle cases like 4 + (unsigned long)&a
13055 if (E->getOpcode() == BO_Add &&
13056 RHSVal.isLValue() && LHSVal.isInt()) {
13057 Result = RHSVal;
13058 addOrSubLValueAsInteger(Result, LHSVal.getInt(), /*IsSub*/false);
13059 return true;
13060 }
13061
13062 if (E->getOpcode() == BO_Sub && LHSVal.isLValue() && RHSVal.isLValue()) {
13063 // Handle (intptr_t)&&A - (intptr_t)&&B.
13064 if (!LHSVal.getLValueOffset().isZero() ||
13065 !RHSVal.getLValueOffset().isZero())
13066 return false;
13067 const Expr *LHSExpr = LHSVal.getLValueBase().dyn_cast<const Expr*>();
13068 const Expr *RHSExpr = RHSVal.getLValueBase().dyn_cast<const Expr*>();
13069 if (!LHSExpr || !RHSExpr)
13070 return false;
13071 const AddrLabelExpr *LHSAddrExpr = dyn_cast<AddrLabelExpr>(LHSExpr);
13072 const AddrLabelExpr *RHSAddrExpr = dyn_cast<AddrLabelExpr>(RHSExpr);
13073 if (!LHSAddrExpr || !RHSAddrExpr)
13074 return false;
13075 // Make sure both labels come from the same function.
13076 if (LHSAddrExpr->getLabel()->getDeclContext() !=
13077 RHSAddrExpr->getLabel()->getDeclContext())
13078 return false;
13079 Result = APValue(LHSAddrExpr, RHSAddrExpr);
13080 return true;
13081 }
13082
13083 // All the remaining cases expect both operands to be an integer
13084 if (!LHSVal.isInt() || !RHSVal.isInt())
13085 return Error(E);
13086
13087 // Set up the width and signedness manually, in case it can't be deduced
13088 // from the operation we're performing.
13089 // FIXME: Don't do this in the cases where we can deduce it.
13090 APSInt Value(Info.Ctx.getIntWidth(E->getType()),
13091 E->getType()->isUnsignedIntegerOrEnumerationType());
13092 if (!handleIntIntBinOp(Info, E, LHSVal.getInt(), E->getOpcode(),
13093 RHSVal.getInt(), Value))
13094 return false;
13095 return Success(Value, E, Result);
13096 }
13097
process(EvalResult & Result)13098 void DataRecursiveIntBinOpEvaluator::process(EvalResult &Result) {
13099 Job &job = Queue.back();
13100
13101 switch (job.Kind) {
13102 case Job::AnyExprKind: {
13103 if (const BinaryOperator *Bop = dyn_cast<BinaryOperator>(job.E)) {
13104 if (shouldEnqueue(Bop)) {
13105 job.Kind = Job::BinOpKind;
13106 enqueue(Bop->getLHS());
13107 return;
13108 }
13109 }
13110
13111 EvaluateExpr(job.E, Result);
13112 Queue.pop_back();
13113 return;
13114 }
13115
13116 case Job::BinOpKind: {
13117 const BinaryOperator *Bop = cast<BinaryOperator>(job.E);
13118 bool SuppressRHSDiags = false;
13119 if (!VisitBinOpLHSOnly(Result, Bop, SuppressRHSDiags)) {
13120 Queue.pop_back();
13121 return;
13122 }
13123 if (SuppressRHSDiags)
13124 job.startSpeculativeEval(Info);
13125 job.LHSResult.swap(Result);
13126 job.Kind = Job::BinOpVisitedLHSKind;
13127 enqueue(Bop->getRHS());
13128 return;
13129 }
13130
13131 case Job::BinOpVisitedLHSKind: {
13132 const BinaryOperator *Bop = cast<BinaryOperator>(job.E);
13133 EvalResult RHS;
13134 RHS.swap(Result);
13135 Result.Failed = !VisitBinOp(job.LHSResult, RHS, Bop, Result.Val);
13136 Queue.pop_back();
13137 return;
13138 }
13139 }
13140
13141 llvm_unreachable("Invalid Job::Kind!");
13142 }
13143
13144 namespace {
13145 enum class CmpResult {
13146 Unequal,
13147 Less,
13148 Equal,
13149 Greater,
13150 Unordered,
13151 };
13152 }
13153
13154 template <class SuccessCB, class AfterCB>
13155 static bool
EvaluateComparisonBinaryOperator(EvalInfo & Info,const BinaryOperator * E,SuccessCB && Success,AfterCB && DoAfter)13156 EvaluateComparisonBinaryOperator(EvalInfo &Info, const BinaryOperator *E,
13157 SuccessCB &&Success, AfterCB &&DoAfter) {
13158 assert(!E->isValueDependent());
13159 assert(E->isComparisonOp() && "expected comparison operator");
13160 assert((E->getOpcode() == BO_Cmp ||
13161 E->getType()->isIntegralOrEnumerationType()) &&
13162 "unsupported binary expression evaluation");
13163 auto Error = [&](const Expr *E) {
13164 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
13165 return false;
13166 };
13167
13168 bool IsRelational = E->isRelationalOp() || E->getOpcode() == BO_Cmp;
13169 bool IsEquality = E->isEqualityOp();
13170
13171 QualType LHSTy = E->getLHS()->getType();
13172 QualType RHSTy = E->getRHS()->getType();
13173
13174 if (LHSTy->isIntegralOrEnumerationType() &&
13175 RHSTy->isIntegralOrEnumerationType()) {
13176 APSInt LHS, RHS;
13177 bool LHSOK = EvaluateInteger(E->getLHS(), LHS, Info);
13178 if (!LHSOK && !Info.noteFailure())
13179 return false;
13180 if (!EvaluateInteger(E->getRHS(), RHS, Info) || !LHSOK)
13181 return false;
13182 if (LHS < RHS)
13183 return Success(CmpResult::Less, E);
13184 if (LHS > RHS)
13185 return Success(CmpResult::Greater, E);
13186 return Success(CmpResult::Equal, E);
13187 }
13188
13189 if (LHSTy->isFixedPointType() || RHSTy->isFixedPointType()) {
13190 APFixedPoint LHSFX(Info.Ctx.getFixedPointSemantics(LHSTy));
13191 APFixedPoint RHSFX(Info.Ctx.getFixedPointSemantics(RHSTy));
13192
13193 bool LHSOK = EvaluateFixedPointOrInteger(E->getLHS(), LHSFX, Info);
13194 if (!LHSOK && !Info.noteFailure())
13195 return false;
13196 if (!EvaluateFixedPointOrInteger(E->getRHS(), RHSFX, Info) || !LHSOK)
13197 return false;
13198 if (LHSFX < RHSFX)
13199 return Success(CmpResult::Less, E);
13200 if (LHSFX > RHSFX)
13201 return Success(CmpResult::Greater, E);
13202 return Success(CmpResult::Equal, E);
13203 }
13204
13205 if (LHSTy->isAnyComplexType() || RHSTy->isAnyComplexType()) {
13206 ComplexValue LHS, RHS;
13207 bool LHSOK;
13208 if (E->isAssignmentOp()) {
13209 LValue LV;
13210 EvaluateLValue(E->getLHS(), LV, Info);
13211 LHSOK = false;
13212 } else if (LHSTy->isRealFloatingType()) {
13213 LHSOK = EvaluateFloat(E->getLHS(), LHS.FloatReal, Info);
13214 if (LHSOK) {
13215 LHS.makeComplexFloat();
13216 LHS.FloatImag = APFloat(LHS.FloatReal.getSemantics());
13217 }
13218 } else {
13219 LHSOK = EvaluateComplex(E->getLHS(), LHS, Info);
13220 }
13221 if (!LHSOK && !Info.noteFailure())
13222 return false;
13223
13224 if (E->getRHS()->getType()->isRealFloatingType()) {
13225 if (!EvaluateFloat(E->getRHS(), RHS.FloatReal, Info) || !LHSOK)
13226 return false;
13227 RHS.makeComplexFloat();
13228 RHS.FloatImag = APFloat(RHS.FloatReal.getSemantics());
13229 } else if (!EvaluateComplex(E->getRHS(), RHS, Info) || !LHSOK)
13230 return false;
13231
13232 if (LHS.isComplexFloat()) {
13233 APFloat::cmpResult CR_r =
13234 LHS.getComplexFloatReal().compare(RHS.getComplexFloatReal());
13235 APFloat::cmpResult CR_i =
13236 LHS.getComplexFloatImag().compare(RHS.getComplexFloatImag());
13237 bool IsEqual = CR_r == APFloat::cmpEqual && CR_i == APFloat::cmpEqual;
13238 return Success(IsEqual ? CmpResult::Equal : CmpResult::Unequal, E);
13239 } else {
13240 assert(IsEquality && "invalid complex comparison");
13241 bool IsEqual = LHS.getComplexIntReal() == RHS.getComplexIntReal() &&
13242 LHS.getComplexIntImag() == RHS.getComplexIntImag();
13243 return Success(IsEqual ? CmpResult::Equal : CmpResult::Unequal, E);
13244 }
13245 }
13246
13247 if (LHSTy->isRealFloatingType() &&
13248 RHSTy->isRealFloatingType()) {
13249 APFloat RHS(0.0), LHS(0.0);
13250
13251 bool LHSOK = EvaluateFloat(E->getRHS(), RHS, Info);
13252 if (!LHSOK && !Info.noteFailure())
13253 return false;
13254
13255 if (!EvaluateFloat(E->getLHS(), LHS, Info) || !LHSOK)
13256 return false;
13257
13258 assert(E->isComparisonOp() && "Invalid binary operator!");
13259 llvm::APFloatBase::cmpResult APFloatCmpResult = LHS.compare(RHS);
13260 if (!Info.InConstantContext &&
13261 APFloatCmpResult == APFloat::cmpUnordered &&
13262 E->getFPFeaturesInEffect(Info.Ctx.getLangOpts()).isFPConstrained()) {
13263 // Note: Compares may raise invalid in some cases involving NaN or sNaN.
13264 Info.FFDiag(E, diag::note_constexpr_float_arithmetic_strict);
13265 return false;
13266 }
13267 auto GetCmpRes = [&]() {
13268 switch (APFloatCmpResult) {
13269 case APFloat::cmpEqual:
13270 return CmpResult::Equal;
13271 case APFloat::cmpLessThan:
13272 return CmpResult::Less;
13273 case APFloat::cmpGreaterThan:
13274 return CmpResult::Greater;
13275 case APFloat::cmpUnordered:
13276 return CmpResult::Unordered;
13277 }
13278 llvm_unreachable("Unrecognised APFloat::cmpResult enum");
13279 };
13280 return Success(GetCmpRes(), E);
13281 }
13282
13283 if (LHSTy->isPointerType() && RHSTy->isPointerType()) {
13284 LValue LHSValue, RHSValue;
13285
13286 bool LHSOK = EvaluatePointer(E->getLHS(), LHSValue, Info);
13287 if (!LHSOK && !Info.noteFailure())
13288 return false;
13289
13290 if (!EvaluatePointer(E->getRHS(), RHSValue, Info) || !LHSOK)
13291 return false;
13292
13293 // Reject differing bases from the normal codepath; we special-case
13294 // comparisons to null.
13295 if (!HasSameBase(LHSValue, RHSValue)) {
13296 auto DiagComparison = [&] (unsigned DiagID, bool Reversed = false) {
13297 std::string LHS = LHSValue.toString(Info.Ctx, E->getLHS()->getType());
13298 std::string RHS = RHSValue.toString(Info.Ctx, E->getRHS()->getType());
13299 Info.FFDiag(E, DiagID)
13300 << (Reversed ? RHS : LHS) << (Reversed ? LHS : RHS);
13301 return false;
13302 };
13303 // Inequalities and subtractions between unrelated pointers have
13304 // unspecified or undefined behavior.
13305 if (!IsEquality)
13306 return DiagComparison(
13307 diag::note_constexpr_pointer_comparison_unspecified);
13308 // A constant address may compare equal to the address of a symbol.
13309 // The one exception is that address of an object cannot compare equal
13310 // to a null pointer constant.
13311 // TODO: Should we restrict this to actual null pointers, and exclude the
13312 // case of zero cast to pointer type?
13313 if ((!LHSValue.Base && !LHSValue.Offset.isZero()) ||
13314 (!RHSValue.Base && !RHSValue.Offset.isZero()))
13315 return DiagComparison(diag::note_constexpr_pointer_constant_comparison,
13316 !RHSValue.Base);
13317 // It's implementation-defined whether distinct literals will have
13318 // distinct addresses. In clang, the result of such a comparison is
13319 // unspecified, so it is not a constant expression. However, we do know
13320 // that the address of a literal will be non-null.
13321 if ((IsLiteralLValue(LHSValue) || IsLiteralLValue(RHSValue)) &&
13322 LHSValue.Base && RHSValue.Base)
13323 return DiagComparison(diag::note_constexpr_literal_comparison);
13324 // We can't tell whether weak symbols will end up pointing to the same
13325 // object.
13326 if (IsWeakLValue(LHSValue) || IsWeakLValue(RHSValue))
13327 return DiagComparison(diag::note_constexpr_pointer_weak_comparison,
13328 !IsWeakLValue(LHSValue));
13329 // We can't compare the address of the start of one object with the
13330 // past-the-end address of another object, per C++ DR1652.
13331 if (LHSValue.Base && LHSValue.Offset.isZero() &&
13332 isOnePastTheEndOfCompleteObject(Info.Ctx, RHSValue))
13333 return DiagComparison(diag::note_constexpr_pointer_comparison_past_end,
13334 true);
13335 if (RHSValue.Base && RHSValue.Offset.isZero() &&
13336 isOnePastTheEndOfCompleteObject(Info.Ctx, LHSValue))
13337 return DiagComparison(diag::note_constexpr_pointer_comparison_past_end,
13338 false);
13339 // We can't tell whether an object is at the same address as another
13340 // zero sized object.
13341 if ((RHSValue.Base && isZeroSized(LHSValue)) ||
13342 (LHSValue.Base && isZeroSized(RHSValue)))
13343 return DiagComparison(
13344 diag::note_constexpr_pointer_comparison_zero_sized);
13345 return Success(CmpResult::Unequal, E);
13346 }
13347
13348 const CharUnits &LHSOffset = LHSValue.getLValueOffset();
13349 const CharUnits &RHSOffset = RHSValue.getLValueOffset();
13350
13351 SubobjectDesignator &LHSDesignator = LHSValue.getLValueDesignator();
13352 SubobjectDesignator &RHSDesignator = RHSValue.getLValueDesignator();
13353
13354 // C++11 [expr.rel]p3:
13355 // Pointers to void (after pointer conversions) can be compared, with a
13356 // result defined as follows: If both pointers represent the same
13357 // address or are both the null pointer value, the result is true if the
13358 // operator is <= or >= and false otherwise; otherwise the result is
13359 // unspecified.
13360 // We interpret this as applying to pointers to *cv* void.
13361 if (LHSTy->isVoidPointerType() && LHSOffset != RHSOffset && IsRelational)
13362 Info.CCEDiag(E, diag::note_constexpr_void_comparison);
13363
13364 // C++11 [expr.rel]p2:
13365 // - If two pointers point to non-static data members of the same object,
13366 // or to subobjects or array elements fo such members, recursively, the
13367 // pointer to the later declared member compares greater provided the
13368 // two members have the same access control and provided their class is
13369 // not a union.
13370 // [...]
13371 // - Otherwise pointer comparisons are unspecified.
13372 if (!LHSDesignator.Invalid && !RHSDesignator.Invalid && IsRelational) {
13373 bool WasArrayIndex;
13374 unsigned Mismatch = FindDesignatorMismatch(
13375 getType(LHSValue.Base), LHSDesignator, RHSDesignator, WasArrayIndex);
13376 // At the point where the designators diverge, the comparison has a
13377 // specified value if:
13378 // - we are comparing array indices
13379 // - we are comparing fields of a union, or fields with the same access
13380 // Otherwise, the result is unspecified and thus the comparison is not a
13381 // constant expression.
13382 if (!WasArrayIndex && Mismatch < LHSDesignator.Entries.size() &&
13383 Mismatch < RHSDesignator.Entries.size()) {
13384 const FieldDecl *LF = getAsField(LHSDesignator.Entries[Mismatch]);
13385 const FieldDecl *RF = getAsField(RHSDesignator.Entries[Mismatch]);
13386 if (!LF && !RF)
13387 Info.CCEDiag(E, diag::note_constexpr_pointer_comparison_base_classes);
13388 else if (!LF)
13389 Info.CCEDiag(E, diag::note_constexpr_pointer_comparison_base_field)
13390 << getAsBaseClass(LHSDesignator.Entries[Mismatch])
13391 << RF->getParent() << RF;
13392 else if (!RF)
13393 Info.CCEDiag(E, diag::note_constexpr_pointer_comparison_base_field)
13394 << getAsBaseClass(RHSDesignator.Entries[Mismatch])
13395 << LF->getParent() << LF;
13396 else if (!LF->getParent()->isUnion() &&
13397 LF->getAccess() != RF->getAccess())
13398 Info.CCEDiag(E,
13399 diag::note_constexpr_pointer_comparison_differing_access)
13400 << LF << LF->getAccess() << RF << RF->getAccess()
13401 << LF->getParent();
13402 }
13403 }
13404
13405 // The comparison here must be unsigned, and performed with the same
13406 // width as the pointer.
13407 unsigned PtrSize = Info.Ctx.getTypeSize(LHSTy);
13408 uint64_t CompareLHS = LHSOffset.getQuantity();
13409 uint64_t CompareRHS = RHSOffset.getQuantity();
13410 assert(PtrSize <= 64 && "Unexpected pointer width");
13411 uint64_t Mask = ~0ULL >> (64 - PtrSize);
13412 CompareLHS &= Mask;
13413 CompareRHS &= Mask;
13414
13415 // If there is a base and this is a relational operator, we can only
13416 // compare pointers within the object in question; otherwise, the result
13417 // depends on where the object is located in memory.
13418 if (!LHSValue.Base.isNull() && IsRelational) {
13419 QualType BaseTy = getType(LHSValue.Base);
13420 if (BaseTy->isIncompleteType())
13421 return Error(E);
13422 CharUnits Size = Info.Ctx.getTypeSizeInChars(BaseTy);
13423 uint64_t OffsetLimit = Size.getQuantity();
13424 if (CompareLHS > OffsetLimit || CompareRHS > OffsetLimit)
13425 return Error(E);
13426 }
13427
13428 if (CompareLHS < CompareRHS)
13429 return Success(CmpResult::Less, E);
13430 if (CompareLHS > CompareRHS)
13431 return Success(CmpResult::Greater, E);
13432 return Success(CmpResult::Equal, E);
13433 }
13434
13435 if (LHSTy->isMemberPointerType()) {
13436 assert(IsEquality && "unexpected member pointer operation");
13437 assert(RHSTy->isMemberPointerType() && "invalid comparison");
13438
13439 MemberPtr LHSValue, RHSValue;
13440
13441 bool LHSOK = EvaluateMemberPointer(E->getLHS(), LHSValue, Info);
13442 if (!LHSOK && !Info.noteFailure())
13443 return false;
13444
13445 if (!EvaluateMemberPointer(E->getRHS(), RHSValue, Info) || !LHSOK)
13446 return false;
13447
13448 // If either operand is a pointer to a weak function, the comparison is not
13449 // constant.
13450 if (LHSValue.getDecl() && LHSValue.getDecl()->isWeak()) {
13451 Info.FFDiag(E, diag::note_constexpr_mem_pointer_weak_comparison)
13452 << LHSValue.getDecl();
13453 return false;
13454 }
13455 if (RHSValue.getDecl() && RHSValue.getDecl()->isWeak()) {
13456 Info.FFDiag(E, diag::note_constexpr_mem_pointer_weak_comparison)
13457 << RHSValue.getDecl();
13458 return false;
13459 }
13460
13461 // C++11 [expr.eq]p2:
13462 // If both operands are null, they compare equal. Otherwise if only one is
13463 // null, they compare unequal.
13464 if (!LHSValue.getDecl() || !RHSValue.getDecl()) {
13465 bool Equal = !LHSValue.getDecl() && !RHSValue.getDecl();
13466 return Success(Equal ? CmpResult::Equal : CmpResult::Unequal, E);
13467 }
13468
13469 // Otherwise if either is a pointer to a virtual member function, the
13470 // result is unspecified.
13471 if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(LHSValue.getDecl()))
13472 if (MD->isVirtual())
13473 Info.CCEDiag(E, diag::note_constexpr_compare_virtual_mem_ptr) << MD;
13474 if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(RHSValue.getDecl()))
13475 if (MD->isVirtual())
13476 Info.CCEDiag(E, diag::note_constexpr_compare_virtual_mem_ptr) << MD;
13477
13478 // Otherwise they compare equal if and only if they would refer to the
13479 // same member of the same most derived object or the same subobject if
13480 // they were dereferenced with a hypothetical object of the associated
13481 // class type.
13482 bool Equal = LHSValue == RHSValue;
13483 return Success(Equal ? CmpResult::Equal : CmpResult::Unequal, E);
13484 }
13485
13486 if (LHSTy->isNullPtrType()) {
13487 assert(E->isComparisonOp() && "unexpected nullptr operation");
13488 assert(RHSTy->isNullPtrType() && "missing pointer conversion");
13489 // C++11 [expr.rel]p4, [expr.eq]p3: If two operands of type std::nullptr_t
13490 // are compared, the result is true of the operator is <=, >= or ==, and
13491 // false otherwise.
13492 LValue Res;
13493 if (!EvaluatePointer(E->getLHS(), Res, Info) ||
13494 !EvaluatePointer(E->getRHS(), Res, Info))
13495 return false;
13496 return Success(CmpResult::Equal, E);
13497 }
13498
13499 return DoAfter();
13500 }
13501
VisitBinCmp(const BinaryOperator * E)13502 bool RecordExprEvaluator::VisitBinCmp(const BinaryOperator *E) {
13503 if (!CheckLiteralType(Info, E))
13504 return false;
13505
13506 auto OnSuccess = [&](CmpResult CR, const BinaryOperator *E) {
13507 ComparisonCategoryResult CCR;
13508 switch (CR) {
13509 case CmpResult::Unequal:
13510 llvm_unreachable("should never produce Unequal for three-way comparison");
13511 case CmpResult::Less:
13512 CCR = ComparisonCategoryResult::Less;
13513 break;
13514 case CmpResult::Equal:
13515 CCR = ComparisonCategoryResult::Equal;
13516 break;
13517 case CmpResult::Greater:
13518 CCR = ComparisonCategoryResult::Greater;
13519 break;
13520 case CmpResult::Unordered:
13521 CCR = ComparisonCategoryResult::Unordered;
13522 break;
13523 }
13524 // Evaluation succeeded. Lookup the information for the comparison category
13525 // type and fetch the VarDecl for the result.
13526 const ComparisonCategoryInfo &CmpInfo =
13527 Info.Ctx.CompCategories.getInfoForType(E->getType());
13528 const VarDecl *VD = CmpInfo.getValueInfo(CmpInfo.makeWeakResult(CCR))->VD;
13529 // Check and evaluate the result as a constant expression.
13530 LValue LV;
13531 LV.set(VD);
13532 if (!handleLValueToRValueConversion(Info, E, E->getType(), LV, Result))
13533 return false;
13534 return CheckConstantExpression(Info, E->getExprLoc(), E->getType(), Result,
13535 ConstantExprKind::Normal);
13536 };
13537 return EvaluateComparisonBinaryOperator(Info, E, OnSuccess, [&]() {
13538 return ExprEvaluatorBaseTy::VisitBinCmp(E);
13539 });
13540 }
13541
VisitCXXParenListInitExpr(const CXXParenListInitExpr * E)13542 bool RecordExprEvaluator::VisitCXXParenListInitExpr(
13543 const CXXParenListInitExpr *E) {
13544 return VisitCXXParenListOrInitListExpr(E, E->getInitExprs());
13545 }
13546
VisitBinaryOperator(const BinaryOperator * E)13547 bool IntExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
13548 // We don't support assignment in C. C++ assignments don't get here because
13549 // assignment is an lvalue in C++.
13550 if (E->isAssignmentOp()) {
13551 Error(E);
13552 if (!Info.noteFailure())
13553 return false;
13554 }
13555
13556 if (DataRecursiveIntBinOpEvaluator::shouldEnqueue(E))
13557 return DataRecursiveIntBinOpEvaluator(*this, Result).Traverse(E);
13558
13559 assert((!E->getLHS()->getType()->isIntegralOrEnumerationType() ||
13560 !E->getRHS()->getType()->isIntegralOrEnumerationType()) &&
13561 "DataRecursiveIntBinOpEvaluator should have handled integral types");
13562
13563 if (E->isComparisonOp()) {
13564 // Evaluate builtin binary comparisons by evaluating them as three-way
13565 // comparisons and then translating the result.
13566 auto OnSuccess = [&](CmpResult CR, const BinaryOperator *E) {
13567 assert((CR != CmpResult::Unequal || E->isEqualityOp()) &&
13568 "should only produce Unequal for equality comparisons");
13569 bool IsEqual = CR == CmpResult::Equal,
13570 IsLess = CR == CmpResult::Less,
13571 IsGreater = CR == CmpResult::Greater;
13572 auto Op = E->getOpcode();
13573 switch (Op) {
13574 default:
13575 llvm_unreachable("unsupported binary operator");
13576 case BO_EQ:
13577 case BO_NE:
13578 return Success(IsEqual == (Op == BO_EQ), E);
13579 case BO_LT:
13580 return Success(IsLess, E);
13581 case BO_GT:
13582 return Success(IsGreater, E);
13583 case BO_LE:
13584 return Success(IsEqual || IsLess, E);
13585 case BO_GE:
13586 return Success(IsEqual || IsGreater, E);
13587 }
13588 };
13589 return EvaluateComparisonBinaryOperator(Info, E, OnSuccess, [&]() {
13590 return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
13591 });
13592 }
13593
13594 QualType LHSTy = E->getLHS()->getType();
13595 QualType RHSTy = E->getRHS()->getType();
13596
13597 if (LHSTy->isPointerType() && RHSTy->isPointerType() &&
13598 E->getOpcode() == BO_Sub) {
13599 LValue LHSValue, RHSValue;
13600
13601 bool LHSOK = EvaluatePointer(E->getLHS(), LHSValue, Info);
13602 if (!LHSOK && !Info.noteFailure())
13603 return false;
13604
13605 if (!EvaluatePointer(E->getRHS(), RHSValue, Info) || !LHSOK)
13606 return false;
13607
13608 // Reject differing bases from the normal codepath; we special-case
13609 // comparisons to null.
13610 if (!HasSameBase(LHSValue, RHSValue)) {
13611 // Handle &&A - &&B.
13612 if (!LHSValue.Offset.isZero() || !RHSValue.Offset.isZero())
13613 return Error(E);
13614 const Expr *LHSExpr = LHSValue.Base.dyn_cast<const Expr *>();
13615 const Expr *RHSExpr = RHSValue.Base.dyn_cast<const Expr *>();
13616 if (!LHSExpr || !RHSExpr)
13617 return Error(E);
13618 const AddrLabelExpr *LHSAddrExpr = dyn_cast<AddrLabelExpr>(LHSExpr);
13619 const AddrLabelExpr *RHSAddrExpr = dyn_cast<AddrLabelExpr>(RHSExpr);
13620 if (!LHSAddrExpr || !RHSAddrExpr)
13621 return Error(E);
13622 // Make sure both labels come from the same function.
13623 if (LHSAddrExpr->getLabel()->getDeclContext() !=
13624 RHSAddrExpr->getLabel()->getDeclContext())
13625 return Error(E);
13626 return Success(APValue(LHSAddrExpr, RHSAddrExpr), E);
13627 }
13628 const CharUnits &LHSOffset = LHSValue.getLValueOffset();
13629 const CharUnits &RHSOffset = RHSValue.getLValueOffset();
13630
13631 SubobjectDesignator &LHSDesignator = LHSValue.getLValueDesignator();
13632 SubobjectDesignator &RHSDesignator = RHSValue.getLValueDesignator();
13633
13634 // C++11 [expr.add]p6:
13635 // Unless both pointers point to elements of the same array object, or
13636 // one past the last element of the array object, the behavior is
13637 // undefined.
13638 if (!LHSDesignator.Invalid && !RHSDesignator.Invalid &&
13639 !AreElementsOfSameArray(getType(LHSValue.Base), LHSDesignator,
13640 RHSDesignator))
13641 Info.CCEDiag(E, diag::note_constexpr_pointer_subtraction_not_same_array);
13642
13643 QualType Type = E->getLHS()->getType();
13644 QualType ElementType = Type->castAs<PointerType>()->getPointeeType();
13645
13646 CharUnits ElementSize;
13647 if (!HandleSizeof(Info, E->getExprLoc(), ElementType, ElementSize))
13648 return false;
13649
13650 // As an extension, a type may have zero size (empty struct or union in
13651 // C, array of zero length). Pointer subtraction in such cases has
13652 // undefined behavior, so is not constant.
13653 if (ElementSize.isZero()) {
13654 Info.FFDiag(E, diag::note_constexpr_pointer_subtraction_zero_size)
13655 << ElementType;
13656 return false;
13657 }
13658
13659 // FIXME: LLVM and GCC both compute LHSOffset - RHSOffset at runtime,
13660 // and produce incorrect results when it overflows. Such behavior
13661 // appears to be non-conforming, but is common, so perhaps we should
13662 // assume the standard intended for such cases to be undefined behavior
13663 // and check for them.
13664
13665 // Compute (LHSOffset - RHSOffset) / Size carefully, checking for
13666 // overflow in the final conversion to ptrdiff_t.
13667 APSInt LHS(llvm::APInt(65, (int64_t)LHSOffset.getQuantity(), true), false);
13668 APSInt RHS(llvm::APInt(65, (int64_t)RHSOffset.getQuantity(), true), false);
13669 APSInt ElemSize(llvm::APInt(65, (int64_t)ElementSize.getQuantity(), true),
13670 false);
13671 APSInt TrueResult = (LHS - RHS) / ElemSize;
13672 APSInt Result = TrueResult.trunc(Info.Ctx.getIntWidth(E->getType()));
13673
13674 if (Result.extend(65) != TrueResult &&
13675 !HandleOverflow(Info, E, TrueResult, E->getType()))
13676 return false;
13677 return Success(Result, E);
13678 }
13679
13680 return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
13681 }
13682
13683 /// VisitUnaryExprOrTypeTraitExpr - Evaluate a sizeof, alignof or vec_step with
13684 /// a result as the expression's type.
VisitUnaryExprOrTypeTraitExpr(const UnaryExprOrTypeTraitExpr * E)13685 bool IntExprEvaluator::VisitUnaryExprOrTypeTraitExpr(
13686 const UnaryExprOrTypeTraitExpr *E) {
13687 switch(E->getKind()) {
13688 case UETT_PreferredAlignOf:
13689 case UETT_AlignOf: {
13690 if (E->isArgumentType())
13691 return Success(GetAlignOfType(Info, E->getArgumentType(), E->getKind()),
13692 E);
13693 else
13694 return Success(GetAlignOfExpr(Info, E->getArgumentExpr(), E->getKind()),
13695 E);
13696 }
13697
13698 case UETT_VecStep: {
13699 QualType Ty = E->getTypeOfArgument();
13700
13701 if (Ty->isVectorType()) {
13702 unsigned n = Ty->castAs<VectorType>()->getNumElements();
13703
13704 // The vec_step built-in functions that take a 3-component
13705 // vector return 4. (OpenCL 1.1 spec 6.11.12)
13706 if (n == 3)
13707 n = 4;
13708
13709 return Success(n, E);
13710 } else
13711 return Success(1, E);
13712 }
13713
13714 case UETT_DataSizeOf:
13715 case UETT_SizeOf: {
13716 QualType SrcTy = E->getTypeOfArgument();
13717 // C++ [expr.sizeof]p2: "When applied to a reference or a reference type,
13718 // the result is the size of the referenced type."
13719 if (const ReferenceType *Ref = SrcTy->getAs<ReferenceType>())
13720 SrcTy = Ref->getPointeeType();
13721
13722 CharUnits Sizeof;
13723 if (!HandleSizeof(Info, E->getExprLoc(), SrcTy, Sizeof,
13724 E->getKind() == UETT_DataSizeOf ? SizeOfType::DataSizeOf
13725 : SizeOfType::SizeOf)) {
13726 return false;
13727 }
13728 return Success(Sizeof, E);
13729 }
13730 case UETT_OpenMPRequiredSimdAlign:
13731 assert(E->isArgumentType());
13732 return Success(
13733 Info.Ctx.toCharUnitsFromBits(
13734 Info.Ctx.getOpenMPDefaultSimdAlign(E->getArgumentType()))
13735 .getQuantity(),
13736 E);
13737 case UETT_VectorElements: {
13738 QualType Ty = E->getTypeOfArgument();
13739 // If the vector has a fixed size, we can determine the number of elements
13740 // at compile time.
13741 if (Ty->isVectorType())
13742 return Success(Ty->castAs<VectorType>()->getNumElements(), E);
13743
13744 assert(Ty->isSizelessVectorType());
13745 if (Info.InConstantContext)
13746 Info.CCEDiag(E, diag::note_constexpr_non_const_vectorelements)
13747 << E->getSourceRange();
13748
13749 return false;
13750 }
13751 }
13752
13753 llvm_unreachable("unknown expr/type trait");
13754 }
13755
VisitOffsetOfExpr(const OffsetOfExpr * OOE)13756 bool IntExprEvaluator::VisitOffsetOfExpr(const OffsetOfExpr *OOE) {
13757 CharUnits Result;
13758 unsigned n = OOE->getNumComponents();
13759 if (n == 0)
13760 return Error(OOE);
13761 QualType CurrentType = OOE->getTypeSourceInfo()->getType();
13762 for (unsigned i = 0; i != n; ++i) {
13763 OffsetOfNode ON = OOE->getComponent(i);
13764 switch (ON.getKind()) {
13765 case OffsetOfNode::Array: {
13766 const Expr *Idx = OOE->getIndexExpr(ON.getArrayExprIndex());
13767 APSInt IdxResult;
13768 if (!EvaluateInteger(Idx, IdxResult, Info))
13769 return false;
13770 const ArrayType *AT = Info.Ctx.getAsArrayType(CurrentType);
13771 if (!AT)
13772 return Error(OOE);
13773 CurrentType = AT->getElementType();
13774 CharUnits ElementSize = Info.Ctx.getTypeSizeInChars(CurrentType);
13775 Result += IdxResult.getSExtValue() * ElementSize;
13776 break;
13777 }
13778
13779 case OffsetOfNode::Field: {
13780 FieldDecl *MemberDecl = ON.getField();
13781 const RecordType *RT = CurrentType->getAs<RecordType>();
13782 if (!RT)
13783 return Error(OOE);
13784 RecordDecl *RD = RT->getDecl();
13785 if (RD->isInvalidDecl()) return false;
13786 const ASTRecordLayout &RL = Info.Ctx.getASTRecordLayout(RD);
13787 unsigned i = MemberDecl->getFieldIndex();
13788 assert(i < RL.getFieldCount() && "offsetof field in wrong type");
13789 Result += Info.Ctx.toCharUnitsFromBits(RL.getFieldOffset(i));
13790 CurrentType = MemberDecl->getType().getNonReferenceType();
13791 break;
13792 }
13793
13794 case OffsetOfNode::Identifier:
13795 llvm_unreachable("dependent __builtin_offsetof");
13796
13797 case OffsetOfNode::Base: {
13798 CXXBaseSpecifier *BaseSpec = ON.getBase();
13799 if (BaseSpec->isVirtual())
13800 return Error(OOE);
13801
13802 // Find the layout of the class whose base we are looking into.
13803 const RecordType *RT = CurrentType->getAs<RecordType>();
13804 if (!RT)
13805 return Error(OOE);
13806 RecordDecl *RD = RT->getDecl();
13807 if (RD->isInvalidDecl()) return false;
13808 const ASTRecordLayout &RL = Info.Ctx.getASTRecordLayout(RD);
13809
13810 // Find the base class itself.
13811 CurrentType = BaseSpec->getType();
13812 const RecordType *BaseRT = CurrentType->getAs<RecordType>();
13813 if (!BaseRT)
13814 return Error(OOE);
13815
13816 // Add the offset to the base.
13817 Result += RL.getBaseClassOffset(cast<CXXRecordDecl>(BaseRT->getDecl()));
13818 break;
13819 }
13820 }
13821 }
13822 return Success(Result, OOE);
13823 }
13824
VisitUnaryOperator(const UnaryOperator * E)13825 bool IntExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) {
13826 switch (E->getOpcode()) {
13827 default:
13828 // Address, indirect, pre/post inc/dec, etc are not valid constant exprs.
13829 // See C99 6.6p3.
13830 return Error(E);
13831 case UO_Extension:
13832 // FIXME: Should extension allow i-c-e extension expressions in its scope?
13833 // If so, we could clear the diagnostic ID.
13834 return Visit(E->getSubExpr());
13835 case UO_Plus:
13836 // The result is just the value.
13837 return Visit(E->getSubExpr());
13838 case UO_Minus: {
13839 if (!Visit(E->getSubExpr()))
13840 return false;
13841 if (!Result.isInt()) return Error(E);
13842 const APSInt &Value = Result.getInt();
13843 if (Value.isSigned() && Value.isMinSignedValue() && E->canOverflow()) {
13844 if (Info.checkingForUndefinedBehavior())
13845 Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
13846 diag::warn_integer_constant_overflow)
13847 << toString(Value, 10) << E->getType() << E->getSourceRange();
13848
13849 if (!HandleOverflow(Info, E, -Value.extend(Value.getBitWidth() + 1),
13850 E->getType()))
13851 return false;
13852 }
13853 return Success(-Value, E);
13854 }
13855 case UO_Not: {
13856 if (!Visit(E->getSubExpr()))
13857 return false;
13858 if (!Result.isInt()) return Error(E);
13859 return Success(~Result.getInt(), E);
13860 }
13861 case UO_LNot: {
13862 bool bres;
13863 if (!EvaluateAsBooleanCondition(E->getSubExpr(), bres, Info))
13864 return false;
13865 return Success(!bres, E);
13866 }
13867 }
13868 }
13869
13870 /// HandleCast - This is used to evaluate implicit or explicit casts where the
13871 /// result type is integer.
VisitCastExpr(const CastExpr * E)13872 bool IntExprEvaluator::VisitCastExpr(const CastExpr *E) {
13873 const Expr *SubExpr = E->getSubExpr();
13874 QualType DestType = E->getType();
13875 QualType SrcType = SubExpr->getType();
13876
13877 switch (E->getCastKind()) {
13878 case CK_BaseToDerived:
13879 case CK_DerivedToBase:
13880 case CK_UncheckedDerivedToBase:
13881 case CK_Dynamic:
13882 case CK_ToUnion:
13883 case CK_ArrayToPointerDecay:
13884 case CK_FunctionToPointerDecay:
13885 case CK_NullToPointer:
13886 case CK_NullToMemberPointer:
13887 case CK_BaseToDerivedMemberPointer:
13888 case CK_DerivedToBaseMemberPointer:
13889 case CK_ReinterpretMemberPointer:
13890 case CK_ConstructorConversion:
13891 case CK_IntegralToPointer:
13892 case CK_ToVoid:
13893 case CK_VectorSplat:
13894 case CK_IntegralToFloating:
13895 case CK_FloatingCast:
13896 case CK_CPointerToObjCPointerCast:
13897 case CK_BlockPointerToObjCPointerCast:
13898 case CK_AnyPointerToBlockPointerCast:
13899 case CK_ObjCObjectLValueCast:
13900 case CK_FloatingRealToComplex:
13901 case CK_FloatingComplexToReal:
13902 case CK_FloatingComplexCast:
13903 case CK_FloatingComplexToIntegralComplex:
13904 case CK_IntegralRealToComplex:
13905 case CK_IntegralComplexCast:
13906 case CK_IntegralComplexToFloatingComplex:
13907 case CK_BuiltinFnToFnPtr:
13908 case CK_ZeroToOCLOpaqueType:
13909 case CK_NonAtomicToAtomic:
13910 case CK_AddressSpaceConversion:
13911 case CK_IntToOCLSampler:
13912 case CK_FloatingToFixedPoint:
13913 case CK_FixedPointToFloating:
13914 case CK_FixedPointCast:
13915 case CK_IntegralToFixedPoint:
13916 case CK_MatrixCast:
13917 llvm_unreachable("invalid cast kind for integral value");
13918
13919 case CK_BitCast:
13920 case CK_Dependent:
13921 case CK_LValueBitCast:
13922 case CK_ARCProduceObject:
13923 case CK_ARCConsumeObject:
13924 case CK_ARCReclaimReturnedObject:
13925 case CK_ARCExtendBlockObject:
13926 case CK_CopyAndAutoreleaseBlockObject:
13927 return Error(E);
13928
13929 case CK_UserDefinedConversion:
13930 case CK_LValueToRValue:
13931 case CK_AtomicToNonAtomic:
13932 case CK_NoOp:
13933 case CK_LValueToRValueBitCast:
13934 return ExprEvaluatorBaseTy::VisitCastExpr(E);
13935
13936 case CK_MemberPointerToBoolean:
13937 case CK_PointerToBoolean:
13938 case CK_IntegralToBoolean:
13939 case CK_FloatingToBoolean:
13940 case CK_BooleanToSignedIntegral:
13941 case CK_FloatingComplexToBoolean:
13942 case CK_IntegralComplexToBoolean: {
13943 bool BoolResult;
13944 if (!EvaluateAsBooleanCondition(SubExpr, BoolResult, Info))
13945 return false;
13946 uint64_t IntResult = BoolResult;
13947 if (BoolResult && E->getCastKind() == CK_BooleanToSignedIntegral)
13948 IntResult = (uint64_t)-1;
13949 return Success(IntResult, E);
13950 }
13951
13952 case CK_FixedPointToIntegral: {
13953 APFixedPoint Src(Info.Ctx.getFixedPointSemantics(SrcType));
13954 if (!EvaluateFixedPoint(SubExpr, Src, Info))
13955 return false;
13956 bool Overflowed;
13957 llvm::APSInt Result = Src.convertToInt(
13958 Info.Ctx.getIntWidth(DestType),
13959 DestType->isSignedIntegerOrEnumerationType(), &Overflowed);
13960 if (Overflowed && !HandleOverflow(Info, E, Result, DestType))
13961 return false;
13962 return Success(Result, E);
13963 }
13964
13965 case CK_FixedPointToBoolean: {
13966 // Unsigned padding does not affect this.
13967 APValue Val;
13968 if (!Evaluate(Val, Info, SubExpr))
13969 return false;
13970 return Success(Val.getFixedPoint().getBoolValue(), E);
13971 }
13972
13973 case CK_IntegralCast: {
13974 if (!Visit(SubExpr))
13975 return false;
13976
13977 if (!Result.isInt()) {
13978 // Allow casts of address-of-label differences if they are no-ops
13979 // or narrowing. (The narrowing case isn't actually guaranteed to
13980 // be constant-evaluatable except in some narrow cases which are hard
13981 // to detect here. We let it through on the assumption the user knows
13982 // what they are doing.)
13983 if (Result.isAddrLabelDiff())
13984 return Info.Ctx.getTypeSize(DestType) <= Info.Ctx.getTypeSize(SrcType);
13985 // Only allow casts of lvalues if they are lossless.
13986 return Info.Ctx.getTypeSize(DestType) == Info.Ctx.getTypeSize(SrcType);
13987 }
13988
13989 if (Info.Ctx.getLangOpts().CPlusPlus && Info.InConstantContext &&
13990 Info.EvalMode == EvalInfo::EM_ConstantExpression &&
13991 DestType->isEnumeralType()) {
13992
13993 bool ConstexprVar = true;
13994
13995 // We know if we are here that we are in a context that we might require
13996 // a constant expression or a context that requires a constant
13997 // value. But if we are initializing a value we don't know if it is a
13998 // constexpr variable or not. We can check the EvaluatingDecl to determine
13999 // if it constexpr or not. If not then we don't want to emit a diagnostic.
14000 if (const auto *VD = dyn_cast_or_null<VarDecl>(
14001 Info.EvaluatingDecl.dyn_cast<const ValueDecl *>()))
14002 ConstexprVar = VD->isConstexpr();
14003
14004 const EnumType *ET = dyn_cast<EnumType>(DestType.getCanonicalType());
14005 const EnumDecl *ED = ET->getDecl();
14006 // Check that the value is within the range of the enumeration values.
14007 //
14008 // This corressponds to [expr.static.cast]p10 which says:
14009 // A value of integral or enumeration type can be explicitly converted
14010 // to a complete enumeration type ... If the enumeration type does not
14011 // have a fixed underlying type, the value is unchanged if the original
14012 // value is within the range of the enumeration values ([dcl.enum]), and
14013 // otherwise, the behavior is undefined.
14014 //
14015 // This was resolved as part of DR2338 which has CD5 status.
14016 if (!ED->isFixed()) {
14017 llvm::APInt Min;
14018 llvm::APInt Max;
14019
14020 ED->getValueRange(Max, Min);
14021 --Max;
14022
14023 if (ED->getNumNegativeBits() && ConstexprVar &&
14024 (Max.slt(Result.getInt().getSExtValue()) ||
14025 Min.sgt(Result.getInt().getSExtValue())))
14026 Info.Ctx.getDiagnostics().Report(
14027 E->getExprLoc(), diag::warn_constexpr_unscoped_enum_out_of_range)
14028 << llvm::toString(Result.getInt(), 10) << Min.getSExtValue()
14029 << Max.getSExtValue() << ED;
14030 else if (!ED->getNumNegativeBits() && ConstexprVar &&
14031 Max.ult(Result.getInt().getZExtValue()))
14032 Info.Ctx.getDiagnostics().Report(
14033 E->getExprLoc(), diag::warn_constexpr_unscoped_enum_out_of_range)
14034 << llvm::toString(Result.getInt(), 10) << Min.getZExtValue()
14035 << Max.getZExtValue() << ED;
14036 }
14037 }
14038
14039 return Success(HandleIntToIntCast(Info, E, DestType, SrcType,
14040 Result.getInt()), E);
14041 }
14042
14043 case CK_PointerToIntegral: {
14044 CCEDiag(E, diag::note_constexpr_invalid_cast)
14045 << 2 << Info.Ctx.getLangOpts().CPlusPlus << E->getSourceRange();
14046
14047 LValue LV;
14048 if (!EvaluatePointer(SubExpr, LV, Info))
14049 return false;
14050
14051 if (LV.getLValueBase()) {
14052 // Only allow based lvalue casts if they are lossless.
14053 // FIXME: Allow a larger integer size than the pointer size, and allow
14054 // narrowing back down to pointer width in subsequent integral casts.
14055 // FIXME: Check integer type's active bits, not its type size.
14056 if (Info.Ctx.getTypeSize(DestType) != Info.Ctx.getTypeSize(SrcType))
14057 return Error(E);
14058
14059 LV.Designator.setInvalid();
14060 LV.moveInto(Result);
14061 return true;
14062 }
14063
14064 APSInt AsInt;
14065 APValue V;
14066 LV.moveInto(V);
14067 if (!V.toIntegralConstant(AsInt, SrcType, Info.Ctx))
14068 llvm_unreachable("Can't cast this!");
14069
14070 return Success(HandleIntToIntCast(Info, E, DestType, SrcType, AsInt), E);
14071 }
14072
14073 case CK_IntegralComplexToReal: {
14074 ComplexValue C;
14075 if (!EvaluateComplex(SubExpr, C, Info))
14076 return false;
14077 return Success(C.getComplexIntReal(), E);
14078 }
14079
14080 case CK_FloatingToIntegral: {
14081 APFloat F(0.0);
14082 if (!EvaluateFloat(SubExpr, F, Info))
14083 return false;
14084
14085 APSInt Value;
14086 if (!HandleFloatToIntCast(Info, E, SrcType, F, DestType, Value))
14087 return false;
14088 return Success(Value, E);
14089 }
14090 }
14091
14092 llvm_unreachable("unknown cast resulting in integral value");
14093 }
14094
VisitUnaryReal(const UnaryOperator * E)14095 bool IntExprEvaluator::VisitUnaryReal(const UnaryOperator *E) {
14096 if (E->getSubExpr()->getType()->isAnyComplexType()) {
14097 ComplexValue LV;
14098 if (!EvaluateComplex(E->getSubExpr(), LV, Info))
14099 return false;
14100 if (!LV.isComplexInt())
14101 return Error(E);
14102 return Success(LV.getComplexIntReal(), E);
14103 }
14104
14105 return Visit(E->getSubExpr());
14106 }
14107
VisitUnaryImag(const UnaryOperator * E)14108 bool IntExprEvaluator::VisitUnaryImag(const UnaryOperator *E) {
14109 if (E->getSubExpr()->getType()->isComplexIntegerType()) {
14110 ComplexValue LV;
14111 if (!EvaluateComplex(E->getSubExpr(), LV, Info))
14112 return false;
14113 if (!LV.isComplexInt())
14114 return Error(E);
14115 return Success(LV.getComplexIntImag(), E);
14116 }
14117
14118 VisitIgnoredValue(E->getSubExpr());
14119 return Success(0, E);
14120 }
14121
VisitSizeOfPackExpr(const SizeOfPackExpr * E)14122 bool IntExprEvaluator::VisitSizeOfPackExpr(const SizeOfPackExpr *E) {
14123 return Success(E->getPackLength(), E);
14124 }
14125
VisitCXXNoexceptExpr(const CXXNoexceptExpr * E)14126 bool IntExprEvaluator::VisitCXXNoexceptExpr(const CXXNoexceptExpr *E) {
14127 return Success(E->getValue(), E);
14128 }
14129
VisitConceptSpecializationExpr(const ConceptSpecializationExpr * E)14130 bool IntExprEvaluator::VisitConceptSpecializationExpr(
14131 const ConceptSpecializationExpr *E) {
14132 return Success(E->isSatisfied(), E);
14133 }
14134
VisitRequiresExpr(const RequiresExpr * E)14135 bool IntExprEvaluator::VisitRequiresExpr(const RequiresExpr *E) {
14136 return Success(E->isSatisfied(), E);
14137 }
14138
VisitUnaryOperator(const UnaryOperator * E)14139 bool FixedPointExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) {
14140 switch (E->getOpcode()) {
14141 default:
14142 // Invalid unary operators
14143 return Error(E);
14144 case UO_Plus:
14145 // The result is just the value.
14146 return Visit(E->getSubExpr());
14147 case UO_Minus: {
14148 if (!Visit(E->getSubExpr())) return false;
14149 if (!Result.isFixedPoint())
14150 return Error(E);
14151 bool Overflowed;
14152 APFixedPoint Negated = Result.getFixedPoint().negate(&Overflowed);
14153 if (Overflowed && !HandleOverflow(Info, E, Negated, E->getType()))
14154 return false;
14155 return Success(Negated, E);
14156 }
14157 case UO_LNot: {
14158 bool bres;
14159 if (!EvaluateAsBooleanCondition(E->getSubExpr(), bres, Info))
14160 return false;
14161 return Success(!bres, E);
14162 }
14163 }
14164 }
14165
VisitCastExpr(const CastExpr * E)14166 bool FixedPointExprEvaluator::VisitCastExpr(const CastExpr *E) {
14167 const Expr *SubExpr = E->getSubExpr();
14168 QualType DestType = E->getType();
14169 assert(DestType->isFixedPointType() &&
14170 "Expected destination type to be a fixed point type");
14171 auto DestFXSema = Info.Ctx.getFixedPointSemantics(DestType);
14172
14173 switch (E->getCastKind()) {
14174 case CK_FixedPointCast: {
14175 APFixedPoint Src(Info.Ctx.getFixedPointSemantics(SubExpr->getType()));
14176 if (!EvaluateFixedPoint(SubExpr, Src, Info))
14177 return false;
14178 bool Overflowed;
14179 APFixedPoint Result = Src.convert(DestFXSema, &Overflowed);
14180 if (Overflowed) {
14181 if (Info.checkingForUndefinedBehavior())
14182 Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
14183 diag::warn_fixedpoint_constant_overflow)
14184 << Result.toString() << E->getType();
14185 if (!HandleOverflow(Info, E, Result, E->getType()))
14186 return false;
14187 }
14188 return Success(Result, E);
14189 }
14190 case CK_IntegralToFixedPoint: {
14191 APSInt Src;
14192 if (!EvaluateInteger(SubExpr, Src, Info))
14193 return false;
14194
14195 bool Overflowed;
14196 APFixedPoint IntResult = APFixedPoint::getFromIntValue(
14197 Src, Info.Ctx.getFixedPointSemantics(DestType), &Overflowed);
14198
14199 if (Overflowed) {
14200 if (Info.checkingForUndefinedBehavior())
14201 Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
14202 diag::warn_fixedpoint_constant_overflow)
14203 << IntResult.toString() << E->getType();
14204 if (!HandleOverflow(Info, E, IntResult, E->getType()))
14205 return false;
14206 }
14207
14208 return Success(IntResult, E);
14209 }
14210 case CK_FloatingToFixedPoint: {
14211 APFloat Src(0.0);
14212 if (!EvaluateFloat(SubExpr, Src, Info))
14213 return false;
14214
14215 bool Overflowed;
14216 APFixedPoint Result = APFixedPoint::getFromFloatValue(
14217 Src, Info.Ctx.getFixedPointSemantics(DestType), &Overflowed);
14218
14219 if (Overflowed) {
14220 if (Info.checkingForUndefinedBehavior())
14221 Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
14222 diag::warn_fixedpoint_constant_overflow)
14223 << Result.toString() << E->getType();
14224 if (!HandleOverflow(Info, E, Result, E->getType()))
14225 return false;
14226 }
14227
14228 return Success(Result, E);
14229 }
14230 case CK_NoOp:
14231 case CK_LValueToRValue:
14232 return ExprEvaluatorBaseTy::VisitCastExpr(E);
14233 default:
14234 return Error(E);
14235 }
14236 }
14237
VisitBinaryOperator(const BinaryOperator * E)14238 bool FixedPointExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
14239 if (E->isPtrMemOp() || E->isAssignmentOp() || E->getOpcode() == BO_Comma)
14240 return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
14241
14242 const Expr *LHS = E->getLHS();
14243 const Expr *RHS = E->getRHS();
14244 FixedPointSemantics ResultFXSema =
14245 Info.Ctx.getFixedPointSemantics(E->getType());
14246
14247 APFixedPoint LHSFX(Info.Ctx.getFixedPointSemantics(LHS->getType()));
14248 if (!EvaluateFixedPointOrInteger(LHS, LHSFX, Info))
14249 return false;
14250 APFixedPoint RHSFX(Info.Ctx.getFixedPointSemantics(RHS->getType()));
14251 if (!EvaluateFixedPointOrInteger(RHS, RHSFX, Info))
14252 return false;
14253
14254 bool OpOverflow = false, ConversionOverflow = false;
14255 APFixedPoint Result(LHSFX.getSemantics());
14256 switch (E->getOpcode()) {
14257 case BO_Add: {
14258 Result = LHSFX.add(RHSFX, &OpOverflow)
14259 .convert(ResultFXSema, &ConversionOverflow);
14260 break;
14261 }
14262 case BO_Sub: {
14263 Result = LHSFX.sub(RHSFX, &OpOverflow)
14264 .convert(ResultFXSema, &ConversionOverflow);
14265 break;
14266 }
14267 case BO_Mul: {
14268 Result = LHSFX.mul(RHSFX, &OpOverflow)
14269 .convert(ResultFXSema, &ConversionOverflow);
14270 break;
14271 }
14272 case BO_Div: {
14273 if (RHSFX.getValue() == 0) {
14274 Info.FFDiag(E, diag::note_expr_divide_by_zero);
14275 return false;
14276 }
14277 Result = LHSFX.div(RHSFX, &OpOverflow)
14278 .convert(ResultFXSema, &ConversionOverflow);
14279 break;
14280 }
14281 case BO_Shl:
14282 case BO_Shr: {
14283 FixedPointSemantics LHSSema = LHSFX.getSemantics();
14284 llvm::APSInt RHSVal = RHSFX.getValue();
14285
14286 unsigned ShiftBW =
14287 LHSSema.getWidth() - (unsigned)LHSSema.hasUnsignedPadding();
14288 unsigned Amt = RHSVal.getLimitedValue(ShiftBW - 1);
14289 // Embedded-C 4.1.6.2.2:
14290 // The right operand must be nonnegative and less than the total number
14291 // of (nonpadding) bits of the fixed-point operand ...
14292 if (RHSVal.isNegative())
14293 Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHSVal;
14294 else if (Amt != RHSVal)
14295 Info.CCEDiag(E, diag::note_constexpr_large_shift)
14296 << RHSVal << E->getType() << ShiftBW;
14297
14298 if (E->getOpcode() == BO_Shl)
14299 Result = LHSFX.shl(Amt, &OpOverflow);
14300 else
14301 Result = LHSFX.shr(Amt, &OpOverflow);
14302 break;
14303 }
14304 default:
14305 return false;
14306 }
14307 if (OpOverflow || ConversionOverflow) {
14308 if (Info.checkingForUndefinedBehavior())
14309 Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
14310 diag::warn_fixedpoint_constant_overflow)
14311 << Result.toString() << E->getType();
14312 if (!HandleOverflow(Info, E, Result, E->getType()))
14313 return false;
14314 }
14315 return Success(Result, E);
14316 }
14317
14318 //===----------------------------------------------------------------------===//
14319 // Float Evaluation
14320 //===----------------------------------------------------------------------===//
14321
14322 namespace {
14323 class FloatExprEvaluator
14324 : public ExprEvaluatorBase<FloatExprEvaluator> {
14325 APFloat &Result;
14326 public:
FloatExprEvaluator(EvalInfo & info,APFloat & result)14327 FloatExprEvaluator(EvalInfo &info, APFloat &result)
14328 : ExprEvaluatorBaseTy(info), Result(result) {}
14329
Success(const APValue & V,const Expr * e)14330 bool Success(const APValue &V, const Expr *e) {
14331 Result = V.getFloat();
14332 return true;
14333 }
14334
ZeroInitialization(const Expr * E)14335 bool ZeroInitialization(const Expr *E) {
14336 Result = APFloat::getZero(Info.Ctx.getFloatTypeSemantics(E->getType()));
14337 return true;
14338 }
14339
14340 bool VisitCallExpr(const CallExpr *E);
14341
14342 bool VisitUnaryOperator(const UnaryOperator *E);
14343 bool VisitBinaryOperator(const BinaryOperator *E);
14344 bool VisitFloatingLiteral(const FloatingLiteral *E);
14345 bool VisitCastExpr(const CastExpr *E);
14346
14347 bool VisitUnaryReal(const UnaryOperator *E);
14348 bool VisitUnaryImag(const UnaryOperator *E);
14349
14350 // FIXME: Missing: array subscript of vector, member of vector
14351 };
14352 } // end anonymous namespace
14353
EvaluateFloat(const Expr * E,APFloat & Result,EvalInfo & Info)14354 static bool EvaluateFloat(const Expr* E, APFloat& Result, EvalInfo &Info) {
14355 assert(!E->isValueDependent());
14356 assert(E->isPRValue() && E->getType()->isRealFloatingType());
14357 return FloatExprEvaluator(Info, Result).Visit(E);
14358 }
14359
TryEvaluateBuiltinNaN(const ASTContext & Context,QualType ResultTy,const Expr * Arg,bool SNaN,llvm::APFloat & Result)14360 static bool TryEvaluateBuiltinNaN(const ASTContext &Context,
14361 QualType ResultTy,
14362 const Expr *Arg,
14363 bool SNaN,
14364 llvm::APFloat &Result) {
14365 const StringLiteral *S = dyn_cast<StringLiteral>(Arg->IgnoreParenCasts());
14366 if (!S) return false;
14367
14368 const llvm::fltSemantics &Sem = Context.getFloatTypeSemantics(ResultTy);
14369
14370 llvm::APInt fill;
14371
14372 // Treat empty strings as if they were zero.
14373 if (S->getString().empty())
14374 fill = llvm::APInt(32, 0);
14375 else if (S->getString().getAsInteger(0, fill))
14376 return false;
14377
14378 if (Context.getTargetInfo().isNan2008()) {
14379 if (SNaN)
14380 Result = llvm::APFloat::getSNaN(Sem, false, &fill);
14381 else
14382 Result = llvm::APFloat::getQNaN(Sem, false, &fill);
14383 } else {
14384 // Prior to IEEE 754-2008, architectures were allowed to choose whether
14385 // the first bit of their significand was set for qNaN or sNaN. MIPS chose
14386 // a different encoding to what became a standard in 2008, and for pre-
14387 // 2008 revisions, MIPS interpreted sNaN-2008 as qNan and qNaN-2008 as
14388 // sNaN. This is now known as "legacy NaN" encoding.
14389 if (SNaN)
14390 Result = llvm::APFloat::getQNaN(Sem, false, &fill);
14391 else
14392 Result = llvm::APFloat::getSNaN(Sem, false, &fill);
14393 }
14394
14395 return true;
14396 }
14397
VisitCallExpr(const CallExpr * E)14398 bool FloatExprEvaluator::VisitCallExpr(const CallExpr *E) {
14399 if (!IsConstantEvaluatedBuiltinCall(E))
14400 return ExprEvaluatorBaseTy::VisitCallExpr(E);
14401
14402 switch (E->getBuiltinCallee()) {
14403 default:
14404 return false;
14405
14406 case Builtin::BI__builtin_huge_val:
14407 case Builtin::BI__builtin_huge_valf:
14408 case Builtin::BI__builtin_huge_vall:
14409 case Builtin::BI__builtin_huge_valf16:
14410 case Builtin::BI__builtin_huge_valf128:
14411 case Builtin::BI__builtin_inf:
14412 case Builtin::BI__builtin_inff:
14413 case Builtin::BI__builtin_infl:
14414 case Builtin::BI__builtin_inff16:
14415 case Builtin::BI__builtin_inff128: {
14416 const llvm::fltSemantics &Sem =
14417 Info.Ctx.getFloatTypeSemantics(E->getType());
14418 Result = llvm::APFloat::getInf(Sem);
14419 return true;
14420 }
14421
14422 case Builtin::BI__builtin_nans:
14423 case Builtin::BI__builtin_nansf:
14424 case Builtin::BI__builtin_nansl:
14425 case Builtin::BI__builtin_nansf16:
14426 case Builtin::BI__builtin_nansf128:
14427 if (!TryEvaluateBuiltinNaN(Info.Ctx, E->getType(), E->getArg(0),
14428 true, Result))
14429 return Error(E);
14430 return true;
14431
14432 case Builtin::BI__builtin_nan:
14433 case Builtin::BI__builtin_nanf:
14434 case Builtin::BI__builtin_nanl:
14435 case Builtin::BI__builtin_nanf16:
14436 case Builtin::BI__builtin_nanf128:
14437 // If this is __builtin_nan() turn this into a nan, otherwise we
14438 // can't constant fold it.
14439 if (!TryEvaluateBuiltinNaN(Info.Ctx, E->getType(), E->getArg(0),
14440 false, Result))
14441 return Error(E);
14442 return true;
14443
14444 case Builtin::BI__builtin_fabs:
14445 case Builtin::BI__builtin_fabsf:
14446 case Builtin::BI__builtin_fabsl:
14447 case Builtin::BI__builtin_fabsf128:
14448 // The C standard says "fabs raises no floating-point exceptions,
14449 // even if x is a signaling NaN. The returned value is independent of
14450 // the current rounding direction mode." Therefore constant folding can
14451 // proceed without regard to the floating point settings.
14452 // Reference, WG14 N2478 F.10.4.3
14453 if (!EvaluateFloat(E->getArg(0), Result, Info))
14454 return false;
14455
14456 if (Result.isNegative())
14457 Result.changeSign();
14458 return true;
14459
14460 case Builtin::BI__arithmetic_fence:
14461 return EvaluateFloat(E->getArg(0), Result, Info);
14462
14463 // FIXME: Builtin::BI__builtin_powi
14464 // FIXME: Builtin::BI__builtin_powif
14465 // FIXME: Builtin::BI__builtin_powil
14466
14467 case Builtin::BI__builtin_copysign:
14468 case Builtin::BI__builtin_copysignf:
14469 case Builtin::BI__builtin_copysignl:
14470 case Builtin::BI__builtin_copysignf128: {
14471 APFloat RHS(0.);
14472 if (!EvaluateFloat(E->getArg(0), Result, Info) ||
14473 !EvaluateFloat(E->getArg(1), RHS, Info))
14474 return false;
14475 Result.copySign(RHS);
14476 return true;
14477 }
14478
14479 case Builtin::BI__builtin_fmax:
14480 case Builtin::BI__builtin_fmaxf:
14481 case Builtin::BI__builtin_fmaxl:
14482 case Builtin::BI__builtin_fmaxf16:
14483 case Builtin::BI__builtin_fmaxf128: {
14484 // TODO: Handle sNaN.
14485 APFloat RHS(0.);
14486 if (!EvaluateFloat(E->getArg(0), Result, Info) ||
14487 !EvaluateFloat(E->getArg(1), RHS, Info))
14488 return false;
14489 // When comparing zeroes, return +0.0 if one of the zeroes is positive.
14490 if (Result.isZero() && RHS.isZero() && Result.isNegative())
14491 Result = RHS;
14492 else if (Result.isNaN() || RHS > Result)
14493 Result = RHS;
14494 return true;
14495 }
14496
14497 case Builtin::BI__builtin_fmin:
14498 case Builtin::BI__builtin_fminf:
14499 case Builtin::BI__builtin_fminl:
14500 case Builtin::BI__builtin_fminf16:
14501 case Builtin::BI__builtin_fminf128: {
14502 // TODO: Handle sNaN.
14503 APFloat RHS(0.);
14504 if (!EvaluateFloat(E->getArg(0), Result, Info) ||
14505 !EvaluateFloat(E->getArg(1), RHS, Info))
14506 return false;
14507 // When comparing zeroes, return -0.0 if one of the zeroes is negative.
14508 if (Result.isZero() && RHS.isZero() && RHS.isNegative())
14509 Result = RHS;
14510 else if (Result.isNaN() || RHS < Result)
14511 Result = RHS;
14512 return true;
14513 }
14514 }
14515 }
14516
VisitUnaryReal(const UnaryOperator * E)14517 bool FloatExprEvaluator::VisitUnaryReal(const UnaryOperator *E) {
14518 if (E->getSubExpr()->getType()->isAnyComplexType()) {
14519 ComplexValue CV;
14520 if (!EvaluateComplex(E->getSubExpr(), CV, Info))
14521 return false;
14522 Result = CV.FloatReal;
14523 return true;
14524 }
14525
14526 return Visit(E->getSubExpr());
14527 }
14528
VisitUnaryImag(const UnaryOperator * E)14529 bool FloatExprEvaluator::VisitUnaryImag(const UnaryOperator *E) {
14530 if (E->getSubExpr()->getType()->isAnyComplexType()) {
14531 ComplexValue CV;
14532 if (!EvaluateComplex(E->getSubExpr(), CV, Info))
14533 return false;
14534 Result = CV.FloatImag;
14535 return true;
14536 }
14537
14538 VisitIgnoredValue(E->getSubExpr());
14539 const llvm::fltSemantics &Sem = Info.Ctx.getFloatTypeSemantics(E->getType());
14540 Result = llvm::APFloat::getZero(Sem);
14541 return true;
14542 }
14543
VisitUnaryOperator(const UnaryOperator * E)14544 bool FloatExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) {
14545 switch (E->getOpcode()) {
14546 default: return Error(E);
14547 case UO_Plus:
14548 return EvaluateFloat(E->getSubExpr(), Result, Info);
14549 case UO_Minus:
14550 // In C standard, WG14 N2478 F.3 p4
14551 // "the unary - raises no floating point exceptions,
14552 // even if the operand is signalling."
14553 if (!EvaluateFloat(E->getSubExpr(), Result, Info))
14554 return false;
14555 Result.changeSign();
14556 return true;
14557 }
14558 }
14559
VisitBinaryOperator(const BinaryOperator * E)14560 bool FloatExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
14561 if (E->isPtrMemOp() || E->isAssignmentOp() || E->getOpcode() == BO_Comma)
14562 return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
14563
14564 APFloat RHS(0.0);
14565 bool LHSOK = EvaluateFloat(E->getLHS(), Result, Info);
14566 if (!LHSOK && !Info.noteFailure())
14567 return false;
14568 return EvaluateFloat(E->getRHS(), RHS, Info) && LHSOK &&
14569 handleFloatFloatBinOp(Info, E, Result, E->getOpcode(), RHS);
14570 }
14571
VisitFloatingLiteral(const FloatingLiteral * E)14572 bool FloatExprEvaluator::VisitFloatingLiteral(const FloatingLiteral *E) {
14573 Result = E->getValue();
14574 return true;
14575 }
14576
VisitCastExpr(const CastExpr * E)14577 bool FloatExprEvaluator::VisitCastExpr(const CastExpr *E) {
14578 const Expr* SubExpr = E->getSubExpr();
14579
14580 switch (E->getCastKind()) {
14581 default:
14582 return ExprEvaluatorBaseTy::VisitCastExpr(E);
14583
14584 case CK_IntegralToFloating: {
14585 APSInt IntResult;
14586 const FPOptions FPO = E->getFPFeaturesInEffect(
14587 Info.Ctx.getLangOpts());
14588 return EvaluateInteger(SubExpr, IntResult, Info) &&
14589 HandleIntToFloatCast(Info, E, FPO, SubExpr->getType(),
14590 IntResult, E->getType(), Result);
14591 }
14592
14593 case CK_FixedPointToFloating: {
14594 APFixedPoint FixResult(Info.Ctx.getFixedPointSemantics(SubExpr->getType()));
14595 if (!EvaluateFixedPoint(SubExpr, FixResult, Info))
14596 return false;
14597 Result =
14598 FixResult.convertToFloat(Info.Ctx.getFloatTypeSemantics(E->getType()));
14599 return true;
14600 }
14601
14602 case CK_FloatingCast: {
14603 if (!Visit(SubExpr))
14604 return false;
14605 return HandleFloatToFloatCast(Info, E, SubExpr->getType(), E->getType(),
14606 Result);
14607 }
14608
14609 case CK_FloatingComplexToReal: {
14610 ComplexValue V;
14611 if (!EvaluateComplex(SubExpr, V, Info))
14612 return false;
14613 Result = V.getComplexFloatReal();
14614 return true;
14615 }
14616 }
14617 }
14618
14619 //===----------------------------------------------------------------------===//
14620 // Complex Evaluation (for float and integer)
14621 //===----------------------------------------------------------------------===//
14622
14623 namespace {
14624 class ComplexExprEvaluator
14625 : public ExprEvaluatorBase<ComplexExprEvaluator> {
14626 ComplexValue &Result;
14627
14628 public:
ComplexExprEvaluator(EvalInfo & info,ComplexValue & Result)14629 ComplexExprEvaluator(EvalInfo &info, ComplexValue &Result)
14630 : ExprEvaluatorBaseTy(info), Result(Result) {}
14631
Success(const APValue & V,const Expr * e)14632 bool Success(const APValue &V, const Expr *e) {
14633 Result.setFrom(V);
14634 return true;
14635 }
14636
14637 bool ZeroInitialization(const Expr *E);
14638
14639 //===--------------------------------------------------------------------===//
14640 // Visitor Methods
14641 //===--------------------------------------------------------------------===//
14642
14643 bool VisitImaginaryLiteral(const ImaginaryLiteral *E);
14644 bool VisitCastExpr(const CastExpr *E);
14645 bool VisitBinaryOperator(const BinaryOperator *E);
14646 bool VisitUnaryOperator(const UnaryOperator *E);
14647 bool VisitInitListExpr(const InitListExpr *E);
14648 bool VisitCallExpr(const CallExpr *E);
14649 };
14650 } // end anonymous namespace
14651
EvaluateComplex(const Expr * E,ComplexValue & Result,EvalInfo & Info)14652 static bool EvaluateComplex(const Expr *E, ComplexValue &Result,
14653 EvalInfo &Info) {
14654 assert(!E->isValueDependent());
14655 assert(E->isPRValue() && E->getType()->isAnyComplexType());
14656 return ComplexExprEvaluator(Info, Result).Visit(E);
14657 }
14658
ZeroInitialization(const Expr * E)14659 bool ComplexExprEvaluator::ZeroInitialization(const Expr *E) {
14660 QualType ElemTy = E->getType()->castAs<ComplexType>()->getElementType();
14661 if (ElemTy->isRealFloatingType()) {
14662 Result.makeComplexFloat();
14663 APFloat Zero = APFloat::getZero(Info.Ctx.getFloatTypeSemantics(ElemTy));
14664 Result.FloatReal = Zero;
14665 Result.FloatImag = Zero;
14666 } else {
14667 Result.makeComplexInt();
14668 APSInt Zero = Info.Ctx.MakeIntValue(0, ElemTy);
14669 Result.IntReal = Zero;
14670 Result.IntImag = Zero;
14671 }
14672 return true;
14673 }
14674
VisitImaginaryLiteral(const ImaginaryLiteral * E)14675 bool ComplexExprEvaluator::VisitImaginaryLiteral(const ImaginaryLiteral *E) {
14676 const Expr* SubExpr = E->getSubExpr();
14677
14678 if (SubExpr->getType()->isRealFloatingType()) {
14679 Result.makeComplexFloat();
14680 APFloat &Imag = Result.FloatImag;
14681 if (!EvaluateFloat(SubExpr, Imag, Info))
14682 return false;
14683
14684 Result.FloatReal = APFloat(Imag.getSemantics());
14685 return true;
14686 } else {
14687 assert(SubExpr->getType()->isIntegerType() &&
14688 "Unexpected imaginary literal.");
14689
14690 Result.makeComplexInt();
14691 APSInt &Imag = Result.IntImag;
14692 if (!EvaluateInteger(SubExpr, Imag, Info))
14693 return false;
14694
14695 Result.IntReal = APSInt(Imag.getBitWidth(), !Imag.isSigned());
14696 return true;
14697 }
14698 }
14699
VisitCastExpr(const CastExpr * E)14700 bool ComplexExprEvaluator::VisitCastExpr(const CastExpr *E) {
14701
14702 switch (E->getCastKind()) {
14703 case CK_BitCast:
14704 case CK_BaseToDerived:
14705 case CK_DerivedToBase:
14706 case CK_UncheckedDerivedToBase:
14707 case CK_Dynamic:
14708 case CK_ToUnion:
14709 case CK_ArrayToPointerDecay:
14710 case CK_FunctionToPointerDecay:
14711 case CK_NullToPointer:
14712 case CK_NullToMemberPointer:
14713 case CK_BaseToDerivedMemberPointer:
14714 case CK_DerivedToBaseMemberPointer:
14715 case CK_MemberPointerToBoolean:
14716 case CK_ReinterpretMemberPointer:
14717 case CK_ConstructorConversion:
14718 case CK_IntegralToPointer:
14719 case CK_PointerToIntegral:
14720 case CK_PointerToBoolean:
14721 case CK_ToVoid:
14722 case CK_VectorSplat:
14723 case CK_IntegralCast:
14724 case CK_BooleanToSignedIntegral:
14725 case CK_IntegralToBoolean:
14726 case CK_IntegralToFloating:
14727 case CK_FloatingToIntegral:
14728 case CK_FloatingToBoolean:
14729 case CK_FloatingCast:
14730 case CK_CPointerToObjCPointerCast:
14731 case CK_BlockPointerToObjCPointerCast:
14732 case CK_AnyPointerToBlockPointerCast:
14733 case CK_ObjCObjectLValueCast:
14734 case CK_FloatingComplexToReal:
14735 case CK_FloatingComplexToBoolean:
14736 case CK_IntegralComplexToReal:
14737 case CK_IntegralComplexToBoolean:
14738 case CK_ARCProduceObject:
14739 case CK_ARCConsumeObject:
14740 case CK_ARCReclaimReturnedObject:
14741 case CK_ARCExtendBlockObject:
14742 case CK_CopyAndAutoreleaseBlockObject:
14743 case CK_BuiltinFnToFnPtr:
14744 case CK_ZeroToOCLOpaqueType:
14745 case CK_NonAtomicToAtomic:
14746 case CK_AddressSpaceConversion:
14747 case CK_IntToOCLSampler:
14748 case CK_FloatingToFixedPoint:
14749 case CK_FixedPointToFloating:
14750 case CK_FixedPointCast:
14751 case CK_FixedPointToBoolean:
14752 case CK_FixedPointToIntegral:
14753 case CK_IntegralToFixedPoint:
14754 case CK_MatrixCast:
14755 llvm_unreachable("invalid cast kind for complex value");
14756
14757 case CK_LValueToRValue:
14758 case CK_AtomicToNonAtomic:
14759 case CK_NoOp:
14760 case CK_LValueToRValueBitCast:
14761 return ExprEvaluatorBaseTy::VisitCastExpr(E);
14762
14763 case CK_Dependent:
14764 case CK_LValueBitCast:
14765 case CK_UserDefinedConversion:
14766 return Error(E);
14767
14768 case CK_FloatingRealToComplex: {
14769 APFloat &Real = Result.FloatReal;
14770 if (!EvaluateFloat(E->getSubExpr(), Real, Info))
14771 return false;
14772
14773 Result.makeComplexFloat();
14774 Result.FloatImag = APFloat(Real.getSemantics());
14775 return true;
14776 }
14777
14778 case CK_FloatingComplexCast: {
14779 if (!Visit(E->getSubExpr()))
14780 return false;
14781
14782 QualType To = E->getType()->castAs<ComplexType>()->getElementType();
14783 QualType From
14784 = E->getSubExpr()->getType()->castAs<ComplexType>()->getElementType();
14785
14786 return HandleFloatToFloatCast(Info, E, From, To, Result.FloatReal) &&
14787 HandleFloatToFloatCast(Info, E, From, To, Result.FloatImag);
14788 }
14789
14790 case CK_FloatingComplexToIntegralComplex: {
14791 if (!Visit(E->getSubExpr()))
14792 return false;
14793
14794 QualType To = E->getType()->castAs<ComplexType>()->getElementType();
14795 QualType From
14796 = E->getSubExpr()->getType()->castAs<ComplexType>()->getElementType();
14797 Result.makeComplexInt();
14798 return HandleFloatToIntCast(Info, E, From, Result.FloatReal,
14799 To, Result.IntReal) &&
14800 HandleFloatToIntCast(Info, E, From, Result.FloatImag,
14801 To, Result.IntImag);
14802 }
14803
14804 case CK_IntegralRealToComplex: {
14805 APSInt &Real = Result.IntReal;
14806 if (!EvaluateInteger(E->getSubExpr(), Real, Info))
14807 return false;
14808
14809 Result.makeComplexInt();
14810 Result.IntImag = APSInt(Real.getBitWidth(), !Real.isSigned());
14811 return true;
14812 }
14813
14814 case CK_IntegralComplexCast: {
14815 if (!Visit(E->getSubExpr()))
14816 return false;
14817
14818 QualType To = E->getType()->castAs<ComplexType>()->getElementType();
14819 QualType From
14820 = E->getSubExpr()->getType()->castAs<ComplexType>()->getElementType();
14821
14822 Result.IntReal = HandleIntToIntCast(Info, E, To, From, Result.IntReal);
14823 Result.IntImag = HandleIntToIntCast(Info, E, To, From, Result.IntImag);
14824 return true;
14825 }
14826
14827 case CK_IntegralComplexToFloatingComplex: {
14828 if (!Visit(E->getSubExpr()))
14829 return false;
14830
14831 const FPOptions FPO = E->getFPFeaturesInEffect(
14832 Info.Ctx.getLangOpts());
14833 QualType To = E->getType()->castAs<ComplexType>()->getElementType();
14834 QualType From
14835 = E->getSubExpr()->getType()->castAs<ComplexType>()->getElementType();
14836 Result.makeComplexFloat();
14837 return HandleIntToFloatCast(Info, E, FPO, From, Result.IntReal,
14838 To, Result.FloatReal) &&
14839 HandleIntToFloatCast(Info, E, FPO, From, Result.IntImag,
14840 To, Result.FloatImag);
14841 }
14842 }
14843
14844 llvm_unreachable("unknown cast resulting in complex value");
14845 }
14846
VisitBinaryOperator(const BinaryOperator * E)14847 bool ComplexExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
14848 if (E->isPtrMemOp() || E->isAssignmentOp() || E->getOpcode() == BO_Comma)
14849 return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
14850
14851 // Track whether the LHS or RHS is real at the type system level. When this is
14852 // the case we can simplify our evaluation strategy.
14853 bool LHSReal = false, RHSReal = false;
14854
14855 bool LHSOK;
14856 if (E->getLHS()->getType()->isRealFloatingType()) {
14857 LHSReal = true;
14858 APFloat &Real = Result.FloatReal;
14859 LHSOK = EvaluateFloat(E->getLHS(), Real, Info);
14860 if (LHSOK) {
14861 Result.makeComplexFloat();
14862 Result.FloatImag = APFloat(Real.getSemantics());
14863 }
14864 } else {
14865 LHSOK = Visit(E->getLHS());
14866 }
14867 if (!LHSOK && !Info.noteFailure())
14868 return false;
14869
14870 ComplexValue RHS;
14871 if (E->getRHS()->getType()->isRealFloatingType()) {
14872 RHSReal = true;
14873 APFloat &Real = RHS.FloatReal;
14874 if (!EvaluateFloat(E->getRHS(), Real, Info) || !LHSOK)
14875 return false;
14876 RHS.makeComplexFloat();
14877 RHS.FloatImag = APFloat(Real.getSemantics());
14878 } else if (!EvaluateComplex(E->getRHS(), RHS, Info) || !LHSOK)
14879 return false;
14880
14881 assert(!(LHSReal && RHSReal) &&
14882 "Cannot have both operands of a complex operation be real.");
14883 switch (E->getOpcode()) {
14884 default: return Error(E);
14885 case BO_Add:
14886 if (Result.isComplexFloat()) {
14887 Result.getComplexFloatReal().add(RHS.getComplexFloatReal(),
14888 APFloat::rmNearestTiesToEven);
14889 if (LHSReal)
14890 Result.getComplexFloatImag() = RHS.getComplexFloatImag();
14891 else if (!RHSReal)
14892 Result.getComplexFloatImag().add(RHS.getComplexFloatImag(),
14893 APFloat::rmNearestTiesToEven);
14894 } else {
14895 Result.getComplexIntReal() += RHS.getComplexIntReal();
14896 Result.getComplexIntImag() += RHS.getComplexIntImag();
14897 }
14898 break;
14899 case BO_Sub:
14900 if (Result.isComplexFloat()) {
14901 Result.getComplexFloatReal().subtract(RHS.getComplexFloatReal(),
14902 APFloat::rmNearestTiesToEven);
14903 if (LHSReal) {
14904 Result.getComplexFloatImag() = RHS.getComplexFloatImag();
14905 Result.getComplexFloatImag().changeSign();
14906 } else if (!RHSReal) {
14907 Result.getComplexFloatImag().subtract(RHS.getComplexFloatImag(),
14908 APFloat::rmNearestTiesToEven);
14909 }
14910 } else {
14911 Result.getComplexIntReal() -= RHS.getComplexIntReal();
14912 Result.getComplexIntImag() -= RHS.getComplexIntImag();
14913 }
14914 break;
14915 case BO_Mul:
14916 if (Result.isComplexFloat()) {
14917 // This is an implementation of complex multiplication according to the
14918 // constraints laid out in C11 Annex G. The implementation uses the
14919 // following naming scheme:
14920 // (a + ib) * (c + id)
14921 ComplexValue LHS = Result;
14922 APFloat &A = LHS.getComplexFloatReal();
14923 APFloat &B = LHS.getComplexFloatImag();
14924 APFloat &C = RHS.getComplexFloatReal();
14925 APFloat &D = RHS.getComplexFloatImag();
14926 APFloat &ResR = Result.getComplexFloatReal();
14927 APFloat &ResI = Result.getComplexFloatImag();
14928 if (LHSReal) {
14929 assert(!RHSReal && "Cannot have two real operands for a complex op!");
14930 ResR = A * C;
14931 ResI = A * D;
14932 } else if (RHSReal) {
14933 ResR = C * A;
14934 ResI = C * B;
14935 } else {
14936 // In the fully general case, we need to handle NaNs and infinities
14937 // robustly.
14938 APFloat AC = A * C;
14939 APFloat BD = B * D;
14940 APFloat AD = A * D;
14941 APFloat BC = B * C;
14942 ResR = AC - BD;
14943 ResI = AD + BC;
14944 if (ResR.isNaN() && ResI.isNaN()) {
14945 bool Recalc = false;
14946 if (A.isInfinity() || B.isInfinity()) {
14947 A = APFloat::copySign(
14948 APFloat(A.getSemantics(), A.isInfinity() ? 1 : 0), A);
14949 B = APFloat::copySign(
14950 APFloat(B.getSemantics(), B.isInfinity() ? 1 : 0), B);
14951 if (C.isNaN())
14952 C = APFloat::copySign(APFloat(C.getSemantics()), C);
14953 if (D.isNaN())
14954 D = APFloat::copySign(APFloat(D.getSemantics()), D);
14955 Recalc = true;
14956 }
14957 if (C.isInfinity() || D.isInfinity()) {
14958 C = APFloat::copySign(
14959 APFloat(C.getSemantics(), C.isInfinity() ? 1 : 0), C);
14960 D = APFloat::copySign(
14961 APFloat(D.getSemantics(), D.isInfinity() ? 1 : 0), D);
14962 if (A.isNaN())
14963 A = APFloat::copySign(APFloat(A.getSemantics()), A);
14964 if (B.isNaN())
14965 B = APFloat::copySign(APFloat(B.getSemantics()), B);
14966 Recalc = true;
14967 }
14968 if (!Recalc && (AC.isInfinity() || BD.isInfinity() ||
14969 AD.isInfinity() || BC.isInfinity())) {
14970 if (A.isNaN())
14971 A = APFloat::copySign(APFloat(A.getSemantics()), A);
14972 if (B.isNaN())
14973 B = APFloat::copySign(APFloat(B.getSemantics()), B);
14974 if (C.isNaN())
14975 C = APFloat::copySign(APFloat(C.getSemantics()), C);
14976 if (D.isNaN())
14977 D = APFloat::copySign(APFloat(D.getSemantics()), D);
14978 Recalc = true;
14979 }
14980 if (Recalc) {
14981 ResR = APFloat::getInf(A.getSemantics()) * (A * C - B * D);
14982 ResI = APFloat::getInf(A.getSemantics()) * (A * D + B * C);
14983 }
14984 }
14985 }
14986 } else {
14987 ComplexValue LHS = Result;
14988 Result.getComplexIntReal() =
14989 (LHS.getComplexIntReal() * RHS.getComplexIntReal() -
14990 LHS.getComplexIntImag() * RHS.getComplexIntImag());
14991 Result.getComplexIntImag() =
14992 (LHS.getComplexIntReal() * RHS.getComplexIntImag() +
14993 LHS.getComplexIntImag() * RHS.getComplexIntReal());
14994 }
14995 break;
14996 case BO_Div:
14997 if (Result.isComplexFloat()) {
14998 // This is an implementation of complex division according to the
14999 // constraints laid out in C11 Annex G. The implementation uses the
15000 // following naming scheme:
15001 // (a + ib) / (c + id)
15002 ComplexValue LHS = Result;
15003 APFloat &A = LHS.getComplexFloatReal();
15004 APFloat &B = LHS.getComplexFloatImag();
15005 APFloat &C = RHS.getComplexFloatReal();
15006 APFloat &D = RHS.getComplexFloatImag();
15007 APFloat &ResR = Result.getComplexFloatReal();
15008 APFloat &ResI = Result.getComplexFloatImag();
15009 if (RHSReal) {
15010 ResR = A / C;
15011 ResI = B / C;
15012 } else {
15013 if (LHSReal) {
15014 // No real optimizations we can do here, stub out with zero.
15015 B = APFloat::getZero(A.getSemantics());
15016 }
15017 int DenomLogB = 0;
15018 APFloat MaxCD = maxnum(abs(C), abs(D));
15019 if (MaxCD.isFinite()) {
15020 DenomLogB = ilogb(MaxCD);
15021 C = scalbn(C, -DenomLogB, APFloat::rmNearestTiesToEven);
15022 D = scalbn(D, -DenomLogB, APFloat::rmNearestTiesToEven);
15023 }
15024 APFloat Denom = C * C + D * D;
15025 ResR = scalbn((A * C + B * D) / Denom, -DenomLogB,
15026 APFloat::rmNearestTiesToEven);
15027 ResI = scalbn((B * C - A * D) / Denom, -DenomLogB,
15028 APFloat::rmNearestTiesToEven);
15029 if (ResR.isNaN() && ResI.isNaN()) {
15030 if (Denom.isPosZero() && (!A.isNaN() || !B.isNaN())) {
15031 ResR = APFloat::getInf(ResR.getSemantics(), C.isNegative()) * A;
15032 ResI = APFloat::getInf(ResR.getSemantics(), C.isNegative()) * B;
15033 } else if ((A.isInfinity() || B.isInfinity()) && C.isFinite() &&
15034 D.isFinite()) {
15035 A = APFloat::copySign(
15036 APFloat(A.getSemantics(), A.isInfinity() ? 1 : 0), A);
15037 B = APFloat::copySign(
15038 APFloat(B.getSemantics(), B.isInfinity() ? 1 : 0), B);
15039 ResR = APFloat::getInf(ResR.getSemantics()) * (A * C + B * D);
15040 ResI = APFloat::getInf(ResI.getSemantics()) * (B * C - A * D);
15041 } else if (MaxCD.isInfinity() && A.isFinite() && B.isFinite()) {
15042 C = APFloat::copySign(
15043 APFloat(C.getSemantics(), C.isInfinity() ? 1 : 0), C);
15044 D = APFloat::copySign(
15045 APFloat(D.getSemantics(), D.isInfinity() ? 1 : 0), D);
15046 ResR = APFloat::getZero(ResR.getSemantics()) * (A * C + B * D);
15047 ResI = APFloat::getZero(ResI.getSemantics()) * (B * C - A * D);
15048 }
15049 }
15050 }
15051 } else {
15052 if (RHS.getComplexIntReal() == 0 && RHS.getComplexIntImag() == 0)
15053 return Error(E, diag::note_expr_divide_by_zero);
15054
15055 ComplexValue LHS = Result;
15056 APSInt Den = RHS.getComplexIntReal() * RHS.getComplexIntReal() +
15057 RHS.getComplexIntImag() * RHS.getComplexIntImag();
15058 Result.getComplexIntReal() =
15059 (LHS.getComplexIntReal() * RHS.getComplexIntReal() +
15060 LHS.getComplexIntImag() * RHS.getComplexIntImag()) / Den;
15061 Result.getComplexIntImag() =
15062 (LHS.getComplexIntImag() * RHS.getComplexIntReal() -
15063 LHS.getComplexIntReal() * RHS.getComplexIntImag()) / Den;
15064 }
15065 break;
15066 }
15067
15068 return true;
15069 }
15070
VisitUnaryOperator(const UnaryOperator * E)15071 bool ComplexExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) {
15072 // Get the operand value into 'Result'.
15073 if (!Visit(E->getSubExpr()))
15074 return false;
15075
15076 switch (E->getOpcode()) {
15077 default:
15078 return Error(E);
15079 case UO_Extension:
15080 return true;
15081 case UO_Plus:
15082 // The result is always just the subexpr.
15083 return true;
15084 case UO_Minus:
15085 if (Result.isComplexFloat()) {
15086 Result.getComplexFloatReal().changeSign();
15087 Result.getComplexFloatImag().changeSign();
15088 }
15089 else {
15090 Result.getComplexIntReal() = -Result.getComplexIntReal();
15091 Result.getComplexIntImag() = -Result.getComplexIntImag();
15092 }
15093 return true;
15094 case UO_Not:
15095 if (Result.isComplexFloat())
15096 Result.getComplexFloatImag().changeSign();
15097 else
15098 Result.getComplexIntImag() = -Result.getComplexIntImag();
15099 return true;
15100 }
15101 }
15102
VisitInitListExpr(const InitListExpr * E)15103 bool ComplexExprEvaluator::VisitInitListExpr(const InitListExpr *E) {
15104 if (E->getNumInits() == 2) {
15105 if (E->getType()->isComplexType()) {
15106 Result.makeComplexFloat();
15107 if (!EvaluateFloat(E->getInit(0), Result.FloatReal, Info))
15108 return false;
15109 if (!EvaluateFloat(E->getInit(1), Result.FloatImag, Info))
15110 return false;
15111 } else {
15112 Result.makeComplexInt();
15113 if (!EvaluateInteger(E->getInit(0), Result.IntReal, Info))
15114 return false;
15115 if (!EvaluateInteger(E->getInit(1), Result.IntImag, Info))
15116 return false;
15117 }
15118 return true;
15119 }
15120 return ExprEvaluatorBaseTy::VisitInitListExpr(E);
15121 }
15122
VisitCallExpr(const CallExpr * E)15123 bool ComplexExprEvaluator::VisitCallExpr(const CallExpr *E) {
15124 if (!IsConstantEvaluatedBuiltinCall(E))
15125 return ExprEvaluatorBaseTy::VisitCallExpr(E);
15126
15127 switch (E->getBuiltinCallee()) {
15128 case Builtin::BI__builtin_complex:
15129 Result.makeComplexFloat();
15130 if (!EvaluateFloat(E->getArg(0), Result.FloatReal, Info))
15131 return false;
15132 if (!EvaluateFloat(E->getArg(1), Result.FloatImag, Info))
15133 return false;
15134 return true;
15135
15136 default:
15137 return false;
15138 }
15139 }
15140
15141 //===----------------------------------------------------------------------===//
15142 // Atomic expression evaluation, essentially just handling the NonAtomicToAtomic
15143 // implicit conversion.
15144 //===----------------------------------------------------------------------===//
15145
15146 namespace {
15147 class AtomicExprEvaluator :
15148 public ExprEvaluatorBase<AtomicExprEvaluator> {
15149 const LValue *This;
15150 APValue &Result;
15151 public:
AtomicExprEvaluator(EvalInfo & Info,const LValue * This,APValue & Result)15152 AtomicExprEvaluator(EvalInfo &Info, const LValue *This, APValue &Result)
15153 : ExprEvaluatorBaseTy(Info), This(This), Result(Result) {}
15154
Success(const APValue & V,const Expr * E)15155 bool Success(const APValue &V, const Expr *E) {
15156 Result = V;
15157 return true;
15158 }
15159
ZeroInitialization(const Expr * E)15160 bool ZeroInitialization(const Expr *E) {
15161 ImplicitValueInitExpr VIE(
15162 E->getType()->castAs<AtomicType>()->getValueType());
15163 // For atomic-qualified class (and array) types in C++, initialize the
15164 // _Atomic-wrapped subobject directly, in-place.
15165 return This ? EvaluateInPlace(Result, Info, *This, &VIE)
15166 : Evaluate(Result, Info, &VIE);
15167 }
15168
VisitCastExpr(const CastExpr * E)15169 bool VisitCastExpr(const CastExpr *E) {
15170 switch (E->getCastKind()) {
15171 default:
15172 return ExprEvaluatorBaseTy::VisitCastExpr(E);
15173 case CK_NullToPointer:
15174 VisitIgnoredValue(E->getSubExpr());
15175 return ZeroInitialization(E);
15176 case CK_NonAtomicToAtomic:
15177 return This ? EvaluateInPlace(Result, Info, *This, E->getSubExpr())
15178 : Evaluate(Result, Info, E->getSubExpr());
15179 }
15180 }
15181 };
15182 } // end anonymous namespace
15183
EvaluateAtomic(const Expr * E,const LValue * This,APValue & Result,EvalInfo & Info)15184 static bool EvaluateAtomic(const Expr *E, const LValue *This, APValue &Result,
15185 EvalInfo &Info) {
15186 assert(!E->isValueDependent());
15187 assert(E->isPRValue() && E->getType()->isAtomicType());
15188 return AtomicExprEvaluator(Info, This, Result).Visit(E);
15189 }
15190
15191 //===----------------------------------------------------------------------===//
15192 // Void expression evaluation, primarily for a cast to void on the LHS of a
15193 // comma operator
15194 //===----------------------------------------------------------------------===//
15195
15196 namespace {
15197 class VoidExprEvaluator
15198 : public ExprEvaluatorBase<VoidExprEvaluator> {
15199 public:
VoidExprEvaluator(EvalInfo & Info)15200 VoidExprEvaluator(EvalInfo &Info) : ExprEvaluatorBaseTy(Info) {}
15201
Success(const APValue & V,const Expr * e)15202 bool Success(const APValue &V, const Expr *e) { return true; }
15203
ZeroInitialization(const Expr * E)15204 bool ZeroInitialization(const Expr *E) { return true; }
15205
VisitCastExpr(const CastExpr * E)15206 bool VisitCastExpr(const CastExpr *E) {
15207 switch (E->getCastKind()) {
15208 default:
15209 return ExprEvaluatorBaseTy::VisitCastExpr(E);
15210 case CK_ToVoid:
15211 VisitIgnoredValue(E->getSubExpr());
15212 return true;
15213 }
15214 }
15215
VisitCallExpr(const CallExpr * E)15216 bool VisitCallExpr(const CallExpr *E) {
15217 if (!IsConstantEvaluatedBuiltinCall(E))
15218 return ExprEvaluatorBaseTy::VisitCallExpr(E);
15219
15220 switch (E->getBuiltinCallee()) {
15221 case Builtin::BI__assume:
15222 case Builtin::BI__builtin_assume:
15223 // The argument is not evaluated!
15224 return true;
15225
15226 case Builtin::BI__builtin_operator_delete:
15227 return HandleOperatorDeleteCall(Info, E);
15228
15229 default:
15230 return false;
15231 }
15232 }
15233
15234 bool VisitCXXDeleteExpr(const CXXDeleteExpr *E);
15235 };
15236 } // end anonymous namespace
15237
VisitCXXDeleteExpr(const CXXDeleteExpr * E)15238 bool VoidExprEvaluator::VisitCXXDeleteExpr(const CXXDeleteExpr *E) {
15239 // We cannot speculatively evaluate a delete expression.
15240 if (Info.SpeculativeEvaluationDepth)
15241 return false;
15242
15243 FunctionDecl *OperatorDelete = E->getOperatorDelete();
15244 if (!OperatorDelete->isReplaceableGlobalAllocationFunction()) {
15245 Info.FFDiag(E, diag::note_constexpr_new_non_replaceable)
15246 << isa<CXXMethodDecl>(OperatorDelete) << OperatorDelete;
15247 return false;
15248 }
15249
15250 const Expr *Arg = E->getArgument();
15251
15252 LValue Pointer;
15253 if (!EvaluatePointer(Arg, Pointer, Info))
15254 return false;
15255 if (Pointer.Designator.Invalid)
15256 return false;
15257
15258 // Deleting a null pointer has no effect.
15259 if (Pointer.isNullPointer()) {
15260 // This is the only case where we need to produce an extension warning:
15261 // the only other way we can succeed is if we find a dynamic allocation,
15262 // and we will have warned when we allocated it in that case.
15263 if (!Info.getLangOpts().CPlusPlus20)
15264 Info.CCEDiag(E, diag::note_constexpr_new);
15265 return true;
15266 }
15267
15268 std::optional<DynAlloc *> Alloc = CheckDeleteKind(
15269 Info, E, Pointer, E->isArrayForm() ? DynAlloc::ArrayNew : DynAlloc::New);
15270 if (!Alloc)
15271 return false;
15272 QualType AllocType = Pointer.Base.getDynamicAllocType();
15273
15274 // For the non-array case, the designator must be empty if the static type
15275 // does not have a virtual destructor.
15276 if (!E->isArrayForm() && Pointer.Designator.Entries.size() != 0 &&
15277 !hasVirtualDestructor(Arg->getType()->getPointeeType())) {
15278 Info.FFDiag(E, diag::note_constexpr_delete_base_nonvirt_dtor)
15279 << Arg->getType()->getPointeeType() << AllocType;
15280 return false;
15281 }
15282
15283 // For a class type with a virtual destructor, the selected operator delete
15284 // is the one looked up when building the destructor.
15285 if (!E->isArrayForm() && !E->isGlobalDelete()) {
15286 const FunctionDecl *VirtualDelete = getVirtualOperatorDelete(AllocType);
15287 if (VirtualDelete &&
15288 !VirtualDelete->isReplaceableGlobalAllocationFunction()) {
15289 Info.FFDiag(E, diag::note_constexpr_new_non_replaceable)
15290 << isa<CXXMethodDecl>(VirtualDelete) << VirtualDelete;
15291 return false;
15292 }
15293 }
15294
15295 if (!HandleDestruction(Info, E->getExprLoc(), Pointer.getLValueBase(),
15296 (*Alloc)->Value, AllocType))
15297 return false;
15298
15299 if (!Info.HeapAllocs.erase(Pointer.Base.dyn_cast<DynamicAllocLValue>())) {
15300 // The element was already erased. This means the destructor call also
15301 // deleted the object.
15302 // FIXME: This probably results in undefined behavior before we get this
15303 // far, and should be diagnosed elsewhere first.
15304 Info.FFDiag(E, diag::note_constexpr_double_delete);
15305 return false;
15306 }
15307
15308 return true;
15309 }
15310
EvaluateVoid(const Expr * E,EvalInfo & Info)15311 static bool EvaluateVoid(const Expr *E, EvalInfo &Info) {
15312 assert(!E->isValueDependent());
15313 assert(E->isPRValue() && E->getType()->isVoidType());
15314 return VoidExprEvaluator(Info).Visit(E);
15315 }
15316
15317 //===----------------------------------------------------------------------===//
15318 // Top level Expr::EvaluateAsRValue method.
15319 //===----------------------------------------------------------------------===//
15320
Evaluate(APValue & Result,EvalInfo & Info,const Expr * E)15321 static bool Evaluate(APValue &Result, EvalInfo &Info, const Expr *E) {
15322 assert(!E->isValueDependent());
15323 // In C, function designators are not lvalues, but we evaluate them as if they
15324 // are.
15325 QualType T = E->getType();
15326 if (E->isGLValue() || T->isFunctionType()) {
15327 LValue LV;
15328 if (!EvaluateLValue(E, LV, Info))
15329 return false;
15330 LV.moveInto(Result);
15331 } else if (T->isVectorType()) {
15332 if (!EvaluateVector(E, Result, Info))
15333 return false;
15334 } else if (T->isIntegralOrEnumerationType()) {
15335 if (!IntExprEvaluator(Info, Result).Visit(E))
15336 return false;
15337 } else if (T->hasPointerRepresentation()) {
15338 LValue LV;
15339 if (!EvaluatePointer(E, LV, Info))
15340 return false;
15341 LV.moveInto(Result);
15342 } else if (T->isRealFloatingType()) {
15343 llvm::APFloat F(0.0);
15344 if (!EvaluateFloat(E, F, Info))
15345 return false;
15346 Result = APValue(F);
15347 } else if (T->isAnyComplexType()) {
15348 ComplexValue C;
15349 if (!EvaluateComplex(E, C, Info))
15350 return false;
15351 C.moveInto(Result);
15352 } else if (T->isFixedPointType()) {
15353 if (!FixedPointExprEvaluator(Info, Result).Visit(E)) return false;
15354 } else if (T->isMemberPointerType()) {
15355 MemberPtr P;
15356 if (!EvaluateMemberPointer(E, P, Info))
15357 return false;
15358 P.moveInto(Result);
15359 return true;
15360 } else if (T->isArrayType()) {
15361 LValue LV;
15362 APValue &Value =
15363 Info.CurrentCall->createTemporary(E, T, ScopeKind::FullExpression, LV);
15364 if (!EvaluateArray(E, LV, Value, Info))
15365 return false;
15366 Result = Value;
15367 } else if (T->isRecordType()) {
15368 LValue LV;
15369 APValue &Value =
15370 Info.CurrentCall->createTemporary(E, T, ScopeKind::FullExpression, LV);
15371 if (!EvaluateRecord(E, LV, Value, Info))
15372 return false;
15373 Result = Value;
15374 } else if (T->isVoidType()) {
15375 if (!Info.getLangOpts().CPlusPlus11)
15376 Info.CCEDiag(E, diag::note_constexpr_nonliteral)
15377 << E->getType();
15378 if (!EvaluateVoid(E, Info))
15379 return false;
15380 } else if (T->isAtomicType()) {
15381 QualType Unqual = T.getAtomicUnqualifiedType();
15382 if (Unqual->isArrayType() || Unqual->isRecordType()) {
15383 LValue LV;
15384 APValue &Value = Info.CurrentCall->createTemporary(
15385 E, Unqual, ScopeKind::FullExpression, LV);
15386 if (!EvaluateAtomic(E, &LV, Value, Info))
15387 return false;
15388 Result = Value;
15389 } else {
15390 if (!EvaluateAtomic(E, nullptr, Result, Info))
15391 return false;
15392 }
15393 } else if (Info.getLangOpts().CPlusPlus11) {
15394 Info.FFDiag(E, diag::note_constexpr_nonliteral) << E->getType();
15395 return false;
15396 } else {
15397 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
15398 return false;
15399 }
15400
15401 return true;
15402 }
15403
15404 /// EvaluateInPlace - Evaluate an expression in-place in an APValue. In some
15405 /// cases, the in-place evaluation is essential, since later initializers for
15406 /// an object can indirectly refer to subobjects which were initialized earlier.
EvaluateInPlace(APValue & Result,EvalInfo & Info,const LValue & This,const Expr * E,bool AllowNonLiteralTypes)15407 static bool EvaluateInPlace(APValue &Result, EvalInfo &Info, const LValue &This,
15408 const Expr *E, bool AllowNonLiteralTypes) {
15409 assert(!E->isValueDependent());
15410
15411 if (!AllowNonLiteralTypes && !CheckLiteralType(Info, E, &This))
15412 return false;
15413
15414 if (E->isPRValue()) {
15415 // Evaluate arrays and record types in-place, so that later initializers can
15416 // refer to earlier-initialized members of the object.
15417 QualType T = E->getType();
15418 if (T->isArrayType())
15419 return EvaluateArray(E, This, Result, Info);
15420 else if (T->isRecordType())
15421 return EvaluateRecord(E, This, Result, Info);
15422 else if (T->isAtomicType()) {
15423 QualType Unqual = T.getAtomicUnqualifiedType();
15424 if (Unqual->isArrayType() || Unqual->isRecordType())
15425 return EvaluateAtomic(E, &This, Result, Info);
15426 }
15427 }
15428
15429 // For any other type, in-place evaluation is unimportant.
15430 return Evaluate(Result, Info, E);
15431 }
15432
15433 /// EvaluateAsRValue - Try to evaluate this expression, performing an implicit
15434 /// lvalue-to-rvalue cast if it is an lvalue.
EvaluateAsRValue(EvalInfo & Info,const Expr * E,APValue & Result)15435 static bool EvaluateAsRValue(EvalInfo &Info, const Expr *E, APValue &Result) {
15436 assert(!E->isValueDependent());
15437
15438 if (E->getType().isNull())
15439 return false;
15440
15441 if (!CheckLiteralType(Info, E))
15442 return false;
15443
15444 if (Info.EnableNewConstInterp) {
15445 if (!Info.Ctx.getInterpContext().evaluateAsRValue(Info, E, Result))
15446 return false;
15447 return CheckConstantExpression(Info, E->getExprLoc(), E->getType(), Result,
15448 ConstantExprKind::Normal);
15449 }
15450
15451 if (!::Evaluate(Result, Info, E))
15452 return false;
15453
15454 // Implicit lvalue-to-rvalue cast.
15455 if (E->isGLValue()) {
15456 LValue LV;
15457 LV.setFrom(Info.Ctx, Result);
15458 if (!handleLValueToRValueConversion(Info, E, E->getType(), LV, Result))
15459 return false;
15460 }
15461
15462 // Check this core constant expression is a constant expression.
15463 return CheckConstantExpression(Info, E->getExprLoc(), E->getType(), Result,
15464 ConstantExprKind::Normal) &&
15465 CheckMemoryLeaks(Info);
15466 }
15467
FastEvaluateAsRValue(const Expr * Exp,Expr::EvalResult & Result,const ASTContext & Ctx,bool & IsConst)15468 static bool FastEvaluateAsRValue(const Expr *Exp, Expr::EvalResult &Result,
15469 const ASTContext &Ctx, bool &IsConst) {
15470 // Fast-path evaluations of integer literals, since we sometimes see files
15471 // containing vast quantities of these.
15472 if (const IntegerLiteral *L = dyn_cast<IntegerLiteral>(Exp)) {
15473 Result.Val = APValue(APSInt(L->getValue(),
15474 L->getType()->isUnsignedIntegerType()));
15475 IsConst = true;
15476 return true;
15477 }
15478
15479 if (const auto *L = dyn_cast<CXXBoolLiteralExpr>(Exp)) {
15480 Result.Val = APValue(APSInt(APInt(1, L->getValue())));
15481 IsConst = true;
15482 return true;
15483 }
15484
15485 if (const auto *CE = dyn_cast<ConstantExpr>(Exp)) {
15486 if (CE->hasAPValueResult()) {
15487 Result.Val = CE->getAPValueResult();
15488 IsConst = true;
15489 return true;
15490 }
15491
15492 // The SubExpr is usually just an IntegerLiteral.
15493 return FastEvaluateAsRValue(CE->getSubExpr(), Result, Ctx, IsConst);
15494 }
15495
15496 // This case should be rare, but we need to check it before we check on
15497 // the type below.
15498 if (Exp->getType().isNull()) {
15499 IsConst = false;
15500 return true;
15501 }
15502
15503 return false;
15504 }
15505
hasUnacceptableSideEffect(Expr::EvalStatus & Result,Expr::SideEffectsKind SEK)15506 static bool hasUnacceptableSideEffect(Expr::EvalStatus &Result,
15507 Expr::SideEffectsKind SEK) {
15508 return (SEK < Expr::SE_AllowSideEffects && Result.HasSideEffects) ||
15509 (SEK < Expr::SE_AllowUndefinedBehavior && Result.HasUndefinedBehavior);
15510 }
15511
EvaluateAsRValue(const Expr * E,Expr::EvalResult & Result,const ASTContext & Ctx,EvalInfo & Info)15512 static bool EvaluateAsRValue(const Expr *E, Expr::EvalResult &Result,
15513 const ASTContext &Ctx, EvalInfo &Info) {
15514 assert(!E->isValueDependent());
15515 bool IsConst;
15516 if (FastEvaluateAsRValue(E, Result, Ctx, IsConst))
15517 return IsConst;
15518
15519 return EvaluateAsRValue(Info, E, Result.Val);
15520 }
15521
EvaluateAsInt(const Expr * E,Expr::EvalResult & ExprResult,const ASTContext & Ctx,Expr::SideEffectsKind AllowSideEffects,EvalInfo & Info)15522 static bool EvaluateAsInt(const Expr *E, Expr::EvalResult &ExprResult,
15523 const ASTContext &Ctx,
15524 Expr::SideEffectsKind AllowSideEffects,
15525 EvalInfo &Info) {
15526 assert(!E->isValueDependent());
15527 if (!E->getType()->isIntegralOrEnumerationType())
15528 return false;
15529
15530 if (!::EvaluateAsRValue(E, ExprResult, Ctx, Info) ||
15531 !ExprResult.Val.isInt() ||
15532 hasUnacceptableSideEffect(ExprResult, AllowSideEffects))
15533 return false;
15534
15535 return true;
15536 }
15537
EvaluateAsFixedPoint(const Expr * E,Expr::EvalResult & ExprResult,const ASTContext & Ctx,Expr::SideEffectsKind AllowSideEffects,EvalInfo & Info)15538 static bool EvaluateAsFixedPoint(const Expr *E, Expr::EvalResult &ExprResult,
15539 const ASTContext &Ctx,
15540 Expr::SideEffectsKind AllowSideEffects,
15541 EvalInfo &Info) {
15542 assert(!E->isValueDependent());
15543 if (!E->getType()->isFixedPointType())
15544 return false;
15545
15546 if (!::EvaluateAsRValue(E, ExprResult, Ctx, Info))
15547 return false;
15548
15549 if (!ExprResult.Val.isFixedPoint() ||
15550 hasUnacceptableSideEffect(ExprResult, AllowSideEffects))
15551 return false;
15552
15553 return true;
15554 }
15555
15556 /// EvaluateAsRValue - Return true if this is a constant which we can fold using
15557 /// any crazy technique (that has nothing to do with language standards) that
15558 /// we want to. If this function returns true, it returns the folded constant
15559 /// in Result. If this expression is a glvalue, an lvalue-to-rvalue conversion
15560 /// will be applied to the result.
EvaluateAsRValue(EvalResult & Result,const ASTContext & Ctx,bool InConstantContext) const15561 bool Expr::EvaluateAsRValue(EvalResult &Result, const ASTContext &Ctx,
15562 bool InConstantContext) const {
15563 assert(!isValueDependent() &&
15564 "Expression evaluator can't be called on a dependent expression.");
15565 ExprTimeTraceScope TimeScope(this, Ctx, "EvaluateAsRValue");
15566 EvalInfo Info(Ctx, Result, EvalInfo::EM_IgnoreSideEffects);
15567 Info.InConstantContext = InConstantContext;
15568 return ::EvaluateAsRValue(this, Result, Ctx, Info);
15569 }
15570
EvaluateAsBooleanCondition(bool & Result,const ASTContext & Ctx,bool InConstantContext) const15571 bool Expr::EvaluateAsBooleanCondition(bool &Result, const ASTContext &Ctx,
15572 bool InConstantContext) const {
15573 assert(!isValueDependent() &&
15574 "Expression evaluator can't be called on a dependent expression.");
15575 ExprTimeTraceScope TimeScope(this, Ctx, "EvaluateAsBooleanCondition");
15576 EvalResult Scratch;
15577 return EvaluateAsRValue(Scratch, Ctx, InConstantContext) &&
15578 HandleConversionToBool(Scratch.Val, Result);
15579 }
15580
EvaluateAsInt(EvalResult & Result,const ASTContext & Ctx,SideEffectsKind AllowSideEffects,bool InConstantContext) const15581 bool Expr::EvaluateAsInt(EvalResult &Result, const ASTContext &Ctx,
15582 SideEffectsKind AllowSideEffects,
15583 bool InConstantContext) const {
15584 assert(!isValueDependent() &&
15585 "Expression evaluator can't be called on a dependent expression.");
15586 ExprTimeTraceScope TimeScope(this, Ctx, "EvaluateAsInt");
15587 EvalInfo Info(Ctx, Result, EvalInfo::EM_IgnoreSideEffects);
15588 Info.InConstantContext = InConstantContext;
15589 return ::EvaluateAsInt(this, Result, Ctx, AllowSideEffects, Info);
15590 }
15591
EvaluateAsFixedPoint(EvalResult & Result,const ASTContext & Ctx,SideEffectsKind AllowSideEffects,bool InConstantContext) const15592 bool Expr::EvaluateAsFixedPoint(EvalResult &Result, const ASTContext &Ctx,
15593 SideEffectsKind AllowSideEffects,
15594 bool InConstantContext) const {
15595 assert(!isValueDependent() &&
15596 "Expression evaluator can't be called on a dependent expression.");
15597 ExprTimeTraceScope TimeScope(this, Ctx, "EvaluateAsFixedPoint");
15598 EvalInfo Info(Ctx, Result, EvalInfo::EM_IgnoreSideEffects);
15599 Info.InConstantContext = InConstantContext;
15600 return ::EvaluateAsFixedPoint(this, Result, Ctx, AllowSideEffects, Info);
15601 }
15602
EvaluateAsFloat(APFloat & Result,const ASTContext & Ctx,SideEffectsKind AllowSideEffects,bool InConstantContext) const15603 bool Expr::EvaluateAsFloat(APFloat &Result, const ASTContext &Ctx,
15604 SideEffectsKind AllowSideEffects,
15605 bool InConstantContext) const {
15606 assert(!isValueDependent() &&
15607 "Expression evaluator can't be called on a dependent expression.");
15608
15609 if (!getType()->isRealFloatingType())
15610 return false;
15611
15612 ExprTimeTraceScope TimeScope(this, Ctx, "EvaluateAsFloat");
15613 EvalResult ExprResult;
15614 if (!EvaluateAsRValue(ExprResult, Ctx, InConstantContext) ||
15615 !ExprResult.Val.isFloat() ||
15616 hasUnacceptableSideEffect(ExprResult, AllowSideEffects))
15617 return false;
15618
15619 Result = ExprResult.Val.getFloat();
15620 return true;
15621 }
15622
EvaluateAsLValue(EvalResult & Result,const ASTContext & Ctx,bool InConstantContext) const15623 bool Expr::EvaluateAsLValue(EvalResult &Result, const ASTContext &Ctx,
15624 bool InConstantContext) const {
15625 assert(!isValueDependent() &&
15626 "Expression evaluator can't be called on a dependent expression.");
15627
15628 ExprTimeTraceScope TimeScope(this, Ctx, "EvaluateAsLValue");
15629 EvalInfo Info(Ctx, Result, EvalInfo::EM_ConstantFold);
15630 Info.InConstantContext = InConstantContext;
15631 LValue LV;
15632 CheckedTemporaries CheckedTemps;
15633 if (!EvaluateLValue(this, LV, Info) || !Info.discardCleanups() ||
15634 Result.HasSideEffects ||
15635 !CheckLValueConstantExpression(Info, getExprLoc(),
15636 Ctx.getLValueReferenceType(getType()), LV,
15637 ConstantExprKind::Normal, CheckedTemps))
15638 return false;
15639
15640 LV.moveInto(Result.Val);
15641 return true;
15642 }
15643
EvaluateDestruction(const ASTContext & Ctx,APValue::LValueBase Base,APValue DestroyedValue,QualType Type,SourceLocation Loc,Expr::EvalStatus & EStatus,bool IsConstantDestruction)15644 static bool EvaluateDestruction(const ASTContext &Ctx, APValue::LValueBase Base,
15645 APValue DestroyedValue, QualType Type,
15646 SourceLocation Loc, Expr::EvalStatus &EStatus,
15647 bool IsConstantDestruction) {
15648 EvalInfo Info(Ctx, EStatus,
15649 IsConstantDestruction ? EvalInfo::EM_ConstantExpression
15650 : EvalInfo::EM_ConstantFold);
15651 Info.setEvaluatingDecl(Base, DestroyedValue,
15652 EvalInfo::EvaluatingDeclKind::Dtor);
15653 Info.InConstantContext = IsConstantDestruction;
15654
15655 LValue LVal;
15656 LVal.set(Base);
15657
15658 if (!HandleDestruction(Info, Loc, Base, DestroyedValue, Type) ||
15659 EStatus.HasSideEffects)
15660 return false;
15661
15662 if (!Info.discardCleanups())
15663 llvm_unreachable("Unhandled cleanup; missing full expression marker?");
15664
15665 return true;
15666 }
15667
EvaluateAsConstantExpr(EvalResult & Result,const ASTContext & Ctx,ConstantExprKind Kind) const15668 bool Expr::EvaluateAsConstantExpr(EvalResult &Result, const ASTContext &Ctx,
15669 ConstantExprKind Kind) const {
15670 assert(!isValueDependent() &&
15671 "Expression evaluator can't be called on a dependent expression.");
15672 bool IsConst;
15673 if (FastEvaluateAsRValue(this, Result, Ctx, IsConst) && Result.Val.hasValue())
15674 return true;
15675
15676 ExprTimeTraceScope TimeScope(this, Ctx, "EvaluateAsConstantExpr");
15677 EvalInfo::EvaluationMode EM = EvalInfo::EM_ConstantExpression;
15678 EvalInfo Info(Ctx, Result, EM);
15679 Info.InConstantContext = true;
15680
15681 if (Info.EnableNewConstInterp) {
15682 if (!Info.Ctx.getInterpContext().evaluate(Info, this, Result.Val))
15683 return false;
15684 return CheckConstantExpression(Info, getExprLoc(),
15685 getStorageType(Ctx, this), Result.Val, Kind);
15686 }
15687
15688 // The type of the object we're initializing is 'const T' for a class NTTP.
15689 QualType T = getType();
15690 if (Kind == ConstantExprKind::ClassTemplateArgument)
15691 T.addConst();
15692
15693 // If we're evaluating a prvalue, fake up a MaterializeTemporaryExpr to
15694 // represent the result of the evaluation. CheckConstantExpression ensures
15695 // this doesn't escape.
15696 MaterializeTemporaryExpr BaseMTE(T, const_cast<Expr*>(this), true);
15697 APValue::LValueBase Base(&BaseMTE);
15698 Info.setEvaluatingDecl(Base, Result.Val);
15699
15700 if (Info.EnableNewConstInterp) {
15701 if (!Info.Ctx.getInterpContext().evaluateAsRValue(Info, this, Result.Val))
15702 return false;
15703 } else {
15704 LValue LVal;
15705 LVal.set(Base);
15706 // C++23 [intro.execution]/p5
15707 // A full-expression is [...] a constant-expression
15708 // So we need to make sure temporary objects are destroyed after having
15709 // evaluating the expression (per C++23 [class.temporary]/p4).
15710 FullExpressionRAII Scope(Info);
15711 if (!::EvaluateInPlace(Result.Val, Info, LVal, this) ||
15712 Result.HasSideEffects || !Scope.destroy())
15713 return false;
15714
15715 if (!Info.discardCleanups())
15716 llvm_unreachable("Unhandled cleanup; missing full expression marker?");
15717 }
15718
15719 if (!CheckConstantExpression(Info, getExprLoc(), getStorageType(Ctx, this),
15720 Result.Val, Kind))
15721 return false;
15722 if (!CheckMemoryLeaks(Info))
15723 return false;
15724
15725 // If this is a class template argument, it's required to have constant
15726 // destruction too.
15727 if (Kind == ConstantExprKind::ClassTemplateArgument &&
15728 (!EvaluateDestruction(Ctx, Base, Result.Val, T, getBeginLoc(), Result,
15729 true) ||
15730 Result.HasSideEffects)) {
15731 // FIXME: Prefix a note to indicate that the problem is lack of constant
15732 // destruction.
15733 return false;
15734 }
15735
15736 return true;
15737 }
15738
EvaluateAsInitializer(APValue & Value,const ASTContext & Ctx,const VarDecl * VD,SmallVectorImpl<PartialDiagnosticAt> & Notes,bool IsConstantInitialization) const15739 bool Expr::EvaluateAsInitializer(APValue &Value, const ASTContext &Ctx,
15740 const VarDecl *VD,
15741 SmallVectorImpl<PartialDiagnosticAt> &Notes,
15742 bool IsConstantInitialization) const {
15743 assert(!isValueDependent() &&
15744 "Expression evaluator can't be called on a dependent expression.");
15745
15746 llvm::TimeTraceScope TimeScope("EvaluateAsInitializer", [&] {
15747 std::string Name;
15748 llvm::raw_string_ostream OS(Name);
15749 VD->printQualifiedName(OS);
15750 return Name;
15751 });
15752
15753 Expr::EvalStatus EStatus;
15754 EStatus.Diag = &Notes;
15755
15756 EvalInfo Info(Ctx, EStatus,
15757 (IsConstantInitialization && Ctx.getLangOpts().CPlusPlus)
15758 ? EvalInfo::EM_ConstantExpression
15759 : EvalInfo::EM_ConstantFold);
15760 Info.setEvaluatingDecl(VD, Value);
15761 Info.InConstantContext = IsConstantInitialization;
15762
15763 SourceLocation DeclLoc = VD->getLocation();
15764 QualType DeclTy = VD->getType();
15765
15766 if (Info.EnableNewConstInterp) {
15767 auto &InterpCtx = const_cast<ASTContext &>(Ctx).getInterpContext();
15768 if (!InterpCtx.evaluateAsInitializer(Info, VD, Value))
15769 return false;
15770
15771 return CheckConstantExpression(Info, DeclLoc, DeclTy, Value,
15772 ConstantExprKind::Normal);
15773 } else {
15774 LValue LVal;
15775 LVal.set(VD);
15776
15777 {
15778 // C++23 [intro.execution]/p5
15779 // A full-expression is ... an init-declarator ([dcl.decl]) or a
15780 // mem-initializer.
15781 // So we need to make sure temporary objects are destroyed after having
15782 // evaluated the expression (per C++23 [class.temporary]/p4).
15783 //
15784 // FIXME: Otherwise this may break test/Modules/pr68702.cpp because the
15785 // serialization code calls ParmVarDecl::getDefaultArg() which strips the
15786 // outermost FullExpr, such as ExprWithCleanups.
15787 FullExpressionRAII Scope(Info);
15788 if (!EvaluateInPlace(Value, Info, LVal, this,
15789 /*AllowNonLiteralTypes=*/true) ||
15790 EStatus.HasSideEffects)
15791 return false;
15792 }
15793
15794 // At this point, any lifetime-extended temporaries are completely
15795 // initialized.
15796 Info.performLifetimeExtension();
15797
15798 if (!Info.discardCleanups())
15799 llvm_unreachable("Unhandled cleanup; missing full expression marker?");
15800 }
15801
15802 return CheckConstantExpression(Info, DeclLoc, DeclTy, Value,
15803 ConstantExprKind::Normal) &&
15804 CheckMemoryLeaks(Info);
15805 }
15806
evaluateDestruction(SmallVectorImpl<PartialDiagnosticAt> & Notes) const15807 bool VarDecl::evaluateDestruction(
15808 SmallVectorImpl<PartialDiagnosticAt> &Notes) const {
15809 Expr::EvalStatus EStatus;
15810 EStatus.Diag = &Notes;
15811
15812 // Only treat the destruction as constant destruction if we formally have
15813 // constant initialization (or are usable in a constant expression).
15814 bool IsConstantDestruction = hasConstantInitialization();
15815
15816 // Make a copy of the value for the destructor to mutate, if we know it.
15817 // Otherwise, treat the value as default-initialized; if the destructor works
15818 // anyway, then the destruction is constant (and must be essentially empty).
15819 APValue DestroyedValue;
15820 if (getEvaluatedValue() && !getEvaluatedValue()->isAbsent())
15821 DestroyedValue = *getEvaluatedValue();
15822 else if (!handleDefaultInitValue(getType(), DestroyedValue))
15823 return false;
15824
15825 if (!EvaluateDestruction(getASTContext(), this, std::move(DestroyedValue),
15826 getType(), getLocation(), EStatus,
15827 IsConstantDestruction) ||
15828 EStatus.HasSideEffects)
15829 return false;
15830
15831 ensureEvaluatedStmt()->HasConstantDestruction = true;
15832 return true;
15833 }
15834
15835 /// isEvaluatable - Call EvaluateAsRValue to see if this expression can be
15836 /// constant folded, but discard the result.
isEvaluatable(const ASTContext & Ctx,SideEffectsKind SEK) const15837 bool Expr::isEvaluatable(const ASTContext &Ctx, SideEffectsKind SEK) const {
15838 assert(!isValueDependent() &&
15839 "Expression evaluator can't be called on a dependent expression.");
15840
15841 EvalResult Result;
15842 return EvaluateAsRValue(Result, Ctx, /* in constant context */ true) &&
15843 !hasUnacceptableSideEffect(Result, SEK);
15844 }
15845
EvaluateKnownConstInt(const ASTContext & Ctx,SmallVectorImpl<PartialDiagnosticAt> * Diag) const15846 APSInt Expr::EvaluateKnownConstInt(const ASTContext &Ctx,
15847 SmallVectorImpl<PartialDiagnosticAt> *Diag) const {
15848 assert(!isValueDependent() &&
15849 "Expression evaluator can't be called on a dependent expression.");
15850
15851 ExprTimeTraceScope TimeScope(this, Ctx, "EvaluateKnownConstInt");
15852 EvalResult EVResult;
15853 EVResult.Diag = Diag;
15854 EvalInfo Info(Ctx, EVResult, EvalInfo::EM_IgnoreSideEffects);
15855 Info.InConstantContext = true;
15856
15857 bool Result = ::EvaluateAsRValue(this, EVResult, Ctx, Info);
15858 (void)Result;
15859 assert(Result && "Could not evaluate expression");
15860 assert(EVResult.Val.isInt() && "Expression did not evaluate to integer");
15861
15862 return EVResult.Val.getInt();
15863 }
15864
EvaluateKnownConstIntCheckOverflow(const ASTContext & Ctx,SmallVectorImpl<PartialDiagnosticAt> * Diag) const15865 APSInt Expr::EvaluateKnownConstIntCheckOverflow(
15866 const ASTContext &Ctx, SmallVectorImpl<PartialDiagnosticAt> *Diag) const {
15867 assert(!isValueDependent() &&
15868 "Expression evaluator can't be called on a dependent expression.");
15869
15870 ExprTimeTraceScope TimeScope(this, Ctx, "EvaluateKnownConstIntCheckOverflow");
15871 EvalResult EVResult;
15872 EVResult.Diag = Diag;
15873 EvalInfo Info(Ctx, EVResult, EvalInfo::EM_IgnoreSideEffects);
15874 Info.InConstantContext = true;
15875 Info.CheckingForUndefinedBehavior = true;
15876
15877 bool Result = ::EvaluateAsRValue(Info, this, EVResult.Val);
15878 (void)Result;
15879 assert(Result && "Could not evaluate expression");
15880 assert(EVResult.Val.isInt() && "Expression did not evaluate to integer");
15881
15882 return EVResult.Val.getInt();
15883 }
15884
EvaluateForOverflow(const ASTContext & Ctx) const15885 void Expr::EvaluateForOverflow(const ASTContext &Ctx) const {
15886 assert(!isValueDependent() &&
15887 "Expression evaluator can't be called on a dependent expression.");
15888
15889 ExprTimeTraceScope TimeScope(this, Ctx, "EvaluateForOverflow");
15890 bool IsConst;
15891 EvalResult EVResult;
15892 if (!FastEvaluateAsRValue(this, EVResult, Ctx, IsConst)) {
15893 EvalInfo Info(Ctx, EVResult, EvalInfo::EM_IgnoreSideEffects);
15894 Info.CheckingForUndefinedBehavior = true;
15895 (void)::EvaluateAsRValue(Info, this, EVResult.Val);
15896 }
15897 }
15898
isGlobalLValue() const15899 bool Expr::EvalResult::isGlobalLValue() const {
15900 assert(Val.isLValue());
15901 return IsGlobalLValue(Val.getLValueBase());
15902 }
15903
15904 /// isIntegerConstantExpr - this recursive routine will test if an expression is
15905 /// an integer constant expression.
15906
15907 /// FIXME: Pass up a reason why! Invalid operation in i-c-e, division by zero,
15908 /// comma, etc
15909
15910 // CheckICE - This function does the fundamental ICE checking: the returned
15911 // ICEDiag contains an ICEKind indicating whether the expression is an ICE,
15912 // and a (possibly null) SourceLocation indicating the location of the problem.
15913 //
15914 // Note that to reduce code duplication, this helper does no evaluation
15915 // itself; the caller checks whether the expression is evaluatable, and
15916 // in the rare cases where CheckICE actually cares about the evaluated
15917 // value, it calls into Evaluate.
15918
15919 namespace {
15920
15921 enum ICEKind {
15922 /// This expression is an ICE.
15923 IK_ICE,
15924 /// This expression is not an ICE, but if it isn't evaluated, it's
15925 /// a legal subexpression for an ICE. This return value is used to handle
15926 /// the comma operator in C99 mode, and non-constant subexpressions.
15927 IK_ICEIfUnevaluated,
15928 /// This expression is not an ICE, and is not a legal subexpression for one.
15929 IK_NotICE
15930 };
15931
15932 struct ICEDiag {
15933 ICEKind Kind;
15934 SourceLocation Loc;
15935
ICEDiag__anonbf0ddd823911::ICEDiag15936 ICEDiag(ICEKind IK, SourceLocation l) : Kind(IK), Loc(l) {}
15937 };
15938
15939 }
15940
NoDiag()15941 static ICEDiag NoDiag() { return ICEDiag(IK_ICE, SourceLocation()); }
15942
Worst(ICEDiag A,ICEDiag B)15943 static ICEDiag Worst(ICEDiag A, ICEDiag B) { return A.Kind >= B.Kind ? A : B; }
15944
CheckEvalInICE(const Expr * E,const ASTContext & Ctx)15945 static ICEDiag CheckEvalInICE(const Expr* E, const ASTContext &Ctx) {
15946 Expr::EvalResult EVResult;
15947 Expr::EvalStatus Status;
15948 EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantExpression);
15949
15950 Info.InConstantContext = true;
15951 if (!::EvaluateAsRValue(E, EVResult, Ctx, Info) || EVResult.HasSideEffects ||
15952 !EVResult.Val.isInt())
15953 return ICEDiag(IK_NotICE, E->getBeginLoc());
15954
15955 return NoDiag();
15956 }
15957
CheckICE(const Expr * E,const ASTContext & Ctx)15958 static ICEDiag CheckICE(const Expr* E, const ASTContext &Ctx) {
15959 assert(!E->isValueDependent() && "Should not see value dependent exprs!");
15960 if (!E->getType()->isIntegralOrEnumerationType())
15961 return ICEDiag(IK_NotICE, E->getBeginLoc());
15962
15963 switch (E->getStmtClass()) {
15964 #define ABSTRACT_STMT(Node)
15965 #define STMT(Node, Base) case Expr::Node##Class:
15966 #define EXPR(Node, Base)
15967 #include "clang/AST/StmtNodes.inc"
15968 case Expr::PredefinedExprClass:
15969 case Expr::FloatingLiteralClass:
15970 case Expr::ImaginaryLiteralClass:
15971 case Expr::StringLiteralClass:
15972 case Expr::ArraySubscriptExprClass:
15973 case Expr::MatrixSubscriptExprClass:
15974 case Expr::OMPArraySectionExprClass:
15975 case Expr::OMPArrayShapingExprClass:
15976 case Expr::OMPIteratorExprClass:
15977 case Expr::MemberExprClass:
15978 case Expr::CompoundAssignOperatorClass:
15979 case Expr::CompoundLiteralExprClass:
15980 case Expr::ExtVectorElementExprClass:
15981 case Expr::DesignatedInitExprClass:
15982 case Expr::ArrayInitLoopExprClass:
15983 case Expr::ArrayInitIndexExprClass:
15984 case Expr::NoInitExprClass:
15985 case Expr::DesignatedInitUpdateExprClass:
15986 case Expr::ImplicitValueInitExprClass:
15987 case Expr::ParenListExprClass:
15988 case Expr::VAArgExprClass:
15989 case Expr::AddrLabelExprClass:
15990 case Expr::StmtExprClass:
15991 case Expr::CXXMemberCallExprClass:
15992 case Expr::CUDAKernelCallExprClass:
15993 case Expr::CXXAddrspaceCastExprClass:
15994 case Expr::CXXDynamicCastExprClass:
15995 case Expr::CXXTypeidExprClass:
15996 case Expr::CXXUuidofExprClass:
15997 case Expr::MSPropertyRefExprClass:
15998 case Expr::MSPropertySubscriptExprClass:
15999 case Expr::CXXNullPtrLiteralExprClass:
16000 case Expr::UserDefinedLiteralClass:
16001 case Expr::CXXThisExprClass:
16002 case Expr::CXXThrowExprClass:
16003 case Expr::CXXNewExprClass:
16004 case Expr::CXXDeleteExprClass:
16005 case Expr::CXXPseudoDestructorExprClass:
16006 case Expr::UnresolvedLookupExprClass:
16007 case Expr::TypoExprClass:
16008 case Expr::RecoveryExprClass:
16009 case Expr::DependentScopeDeclRefExprClass:
16010 case Expr::CXXConstructExprClass:
16011 case Expr::CXXInheritedCtorInitExprClass:
16012 case Expr::CXXStdInitializerListExprClass:
16013 case Expr::CXXBindTemporaryExprClass:
16014 case Expr::ExprWithCleanupsClass:
16015 case Expr::CXXTemporaryObjectExprClass:
16016 case Expr::CXXUnresolvedConstructExprClass:
16017 case Expr::CXXDependentScopeMemberExprClass:
16018 case Expr::UnresolvedMemberExprClass:
16019 case Expr::ObjCStringLiteralClass:
16020 case Expr::ObjCBoxedExprClass:
16021 case Expr::ObjCArrayLiteralClass:
16022 case Expr::ObjCDictionaryLiteralClass:
16023 case Expr::ObjCEncodeExprClass:
16024 case Expr::ObjCMessageExprClass:
16025 case Expr::ObjCSelectorExprClass:
16026 case Expr::ObjCProtocolExprClass:
16027 case Expr::ObjCIvarRefExprClass:
16028 case Expr::ObjCPropertyRefExprClass:
16029 case Expr::ObjCSubscriptRefExprClass:
16030 case Expr::ObjCIsaExprClass:
16031 case Expr::ObjCAvailabilityCheckExprClass:
16032 case Expr::ShuffleVectorExprClass:
16033 case Expr::ConvertVectorExprClass:
16034 case Expr::BlockExprClass:
16035 case Expr::NoStmtClass:
16036 case Expr::OpaqueValueExprClass:
16037 case Expr::PackExpansionExprClass:
16038 case Expr::SubstNonTypeTemplateParmPackExprClass:
16039 case Expr::FunctionParmPackExprClass:
16040 case Expr::AsTypeExprClass:
16041 case Expr::ObjCIndirectCopyRestoreExprClass:
16042 case Expr::MaterializeTemporaryExprClass:
16043 case Expr::PseudoObjectExprClass:
16044 case Expr::AtomicExprClass:
16045 case Expr::LambdaExprClass:
16046 case Expr::CXXFoldExprClass:
16047 case Expr::CoawaitExprClass:
16048 case Expr::DependentCoawaitExprClass:
16049 case Expr::CoyieldExprClass:
16050 case Expr::SYCLUniqueStableNameExprClass:
16051 case Expr::CXXParenListInitExprClass:
16052 return ICEDiag(IK_NotICE, E->getBeginLoc());
16053
16054 case Expr::InitListExprClass: {
16055 // C++03 [dcl.init]p13: If T is a scalar type, then a declaration of the
16056 // form "T x = { a };" is equivalent to "T x = a;".
16057 // Unless we're initializing a reference, T is a scalar as it is known to be
16058 // of integral or enumeration type.
16059 if (E->isPRValue())
16060 if (cast<InitListExpr>(E)->getNumInits() == 1)
16061 return CheckICE(cast<InitListExpr>(E)->getInit(0), Ctx);
16062 return ICEDiag(IK_NotICE, E->getBeginLoc());
16063 }
16064
16065 case Expr::SizeOfPackExprClass:
16066 case Expr::GNUNullExprClass:
16067 case Expr::SourceLocExprClass:
16068 return NoDiag();
16069
16070 case Expr::SubstNonTypeTemplateParmExprClass:
16071 return
16072 CheckICE(cast<SubstNonTypeTemplateParmExpr>(E)->getReplacement(), Ctx);
16073
16074 case Expr::ConstantExprClass:
16075 return CheckICE(cast<ConstantExpr>(E)->getSubExpr(), Ctx);
16076
16077 case Expr::ParenExprClass:
16078 return CheckICE(cast<ParenExpr>(E)->getSubExpr(), Ctx);
16079 case Expr::GenericSelectionExprClass:
16080 return CheckICE(cast<GenericSelectionExpr>(E)->getResultExpr(), Ctx);
16081 case Expr::IntegerLiteralClass:
16082 case Expr::FixedPointLiteralClass:
16083 case Expr::CharacterLiteralClass:
16084 case Expr::ObjCBoolLiteralExprClass:
16085 case Expr::CXXBoolLiteralExprClass:
16086 case Expr::CXXScalarValueInitExprClass:
16087 case Expr::TypeTraitExprClass:
16088 case Expr::ConceptSpecializationExprClass:
16089 case Expr::RequiresExprClass:
16090 case Expr::ArrayTypeTraitExprClass:
16091 case Expr::ExpressionTraitExprClass:
16092 case Expr::CXXNoexceptExprClass:
16093 return NoDiag();
16094 case Expr::CallExprClass:
16095 case Expr::CXXOperatorCallExprClass: {
16096 // C99 6.6/3 allows function calls within unevaluated subexpressions of
16097 // constant expressions, but they can never be ICEs because an ICE cannot
16098 // contain an operand of (pointer to) function type.
16099 const CallExpr *CE = cast<CallExpr>(E);
16100 if (CE->getBuiltinCallee())
16101 return CheckEvalInICE(E, Ctx);
16102 return ICEDiag(IK_NotICE, E->getBeginLoc());
16103 }
16104 case Expr::CXXRewrittenBinaryOperatorClass:
16105 return CheckICE(cast<CXXRewrittenBinaryOperator>(E)->getSemanticForm(),
16106 Ctx);
16107 case Expr::DeclRefExprClass: {
16108 const NamedDecl *D = cast<DeclRefExpr>(E)->getDecl();
16109 if (isa<EnumConstantDecl>(D))
16110 return NoDiag();
16111
16112 // C++ and OpenCL (FIXME: spec reference?) allow reading const-qualified
16113 // integer variables in constant expressions:
16114 //
16115 // C++ 7.1.5.1p2
16116 // A variable of non-volatile const-qualified integral or enumeration
16117 // type initialized by an ICE can be used in ICEs.
16118 //
16119 // We sometimes use CheckICE to check the C++98 rules in C++11 mode. In
16120 // that mode, use of reference variables should not be allowed.
16121 const VarDecl *VD = dyn_cast<VarDecl>(D);
16122 if (VD && VD->isUsableInConstantExpressions(Ctx) &&
16123 !VD->getType()->isReferenceType())
16124 return NoDiag();
16125
16126 return ICEDiag(IK_NotICE, E->getBeginLoc());
16127 }
16128 case Expr::UnaryOperatorClass: {
16129 const UnaryOperator *Exp = cast<UnaryOperator>(E);
16130 switch (Exp->getOpcode()) {
16131 case UO_PostInc:
16132 case UO_PostDec:
16133 case UO_PreInc:
16134 case UO_PreDec:
16135 case UO_AddrOf:
16136 case UO_Deref:
16137 case UO_Coawait:
16138 // C99 6.6/3 allows increment and decrement within unevaluated
16139 // subexpressions of constant expressions, but they can never be ICEs
16140 // because an ICE cannot contain an lvalue operand.
16141 return ICEDiag(IK_NotICE, E->getBeginLoc());
16142 case UO_Extension:
16143 case UO_LNot:
16144 case UO_Plus:
16145 case UO_Minus:
16146 case UO_Not:
16147 case UO_Real:
16148 case UO_Imag:
16149 return CheckICE(Exp->getSubExpr(), Ctx);
16150 }
16151 llvm_unreachable("invalid unary operator class");
16152 }
16153 case Expr::OffsetOfExprClass: {
16154 // Note that per C99, offsetof must be an ICE. And AFAIK, using
16155 // EvaluateAsRValue matches the proposed gcc behavior for cases like
16156 // "offsetof(struct s{int x[4];}, x[1.0])". This doesn't affect
16157 // compliance: we should warn earlier for offsetof expressions with
16158 // array subscripts that aren't ICEs, and if the array subscripts
16159 // are ICEs, the value of the offsetof must be an integer constant.
16160 return CheckEvalInICE(E, Ctx);
16161 }
16162 case Expr::UnaryExprOrTypeTraitExprClass: {
16163 const UnaryExprOrTypeTraitExpr *Exp = cast<UnaryExprOrTypeTraitExpr>(E);
16164 if ((Exp->getKind() == UETT_SizeOf) &&
16165 Exp->getTypeOfArgument()->isVariableArrayType())
16166 return ICEDiag(IK_NotICE, E->getBeginLoc());
16167 return NoDiag();
16168 }
16169 case Expr::BinaryOperatorClass: {
16170 const BinaryOperator *Exp = cast<BinaryOperator>(E);
16171 switch (Exp->getOpcode()) {
16172 case BO_PtrMemD:
16173 case BO_PtrMemI:
16174 case BO_Assign:
16175 case BO_MulAssign:
16176 case BO_DivAssign:
16177 case BO_RemAssign:
16178 case BO_AddAssign:
16179 case BO_SubAssign:
16180 case BO_ShlAssign:
16181 case BO_ShrAssign:
16182 case BO_AndAssign:
16183 case BO_XorAssign:
16184 case BO_OrAssign:
16185 // C99 6.6/3 allows assignments within unevaluated subexpressions of
16186 // constant expressions, but they can never be ICEs because an ICE cannot
16187 // contain an lvalue operand.
16188 return ICEDiag(IK_NotICE, E->getBeginLoc());
16189
16190 case BO_Mul:
16191 case BO_Div:
16192 case BO_Rem:
16193 case BO_Add:
16194 case BO_Sub:
16195 case BO_Shl:
16196 case BO_Shr:
16197 case BO_LT:
16198 case BO_GT:
16199 case BO_LE:
16200 case BO_GE:
16201 case BO_EQ:
16202 case BO_NE:
16203 case BO_And:
16204 case BO_Xor:
16205 case BO_Or:
16206 case BO_Comma:
16207 case BO_Cmp: {
16208 ICEDiag LHSResult = CheckICE(Exp->getLHS(), Ctx);
16209 ICEDiag RHSResult = CheckICE(Exp->getRHS(), Ctx);
16210 if (Exp->getOpcode() == BO_Div ||
16211 Exp->getOpcode() == BO_Rem) {
16212 // EvaluateAsRValue gives an error for undefined Div/Rem, so make sure
16213 // we don't evaluate one.
16214 if (LHSResult.Kind == IK_ICE && RHSResult.Kind == IK_ICE) {
16215 llvm::APSInt REval = Exp->getRHS()->EvaluateKnownConstInt(Ctx);
16216 if (REval == 0)
16217 return ICEDiag(IK_ICEIfUnevaluated, E->getBeginLoc());
16218 if (REval.isSigned() && REval.isAllOnes()) {
16219 llvm::APSInt LEval = Exp->getLHS()->EvaluateKnownConstInt(Ctx);
16220 if (LEval.isMinSignedValue())
16221 return ICEDiag(IK_ICEIfUnevaluated, E->getBeginLoc());
16222 }
16223 }
16224 }
16225 if (Exp->getOpcode() == BO_Comma) {
16226 if (Ctx.getLangOpts().C99) {
16227 // C99 6.6p3 introduces a strange edge case: comma can be in an ICE
16228 // if it isn't evaluated.
16229 if (LHSResult.Kind == IK_ICE && RHSResult.Kind == IK_ICE)
16230 return ICEDiag(IK_ICEIfUnevaluated, E->getBeginLoc());
16231 } else {
16232 // In both C89 and C++, commas in ICEs are illegal.
16233 return ICEDiag(IK_NotICE, E->getBeginLoc());
16234 }
16235 }
16236 return Worst(LHSResult, RHSResult);
16237 }
16238 case BO_LAnd:
16239 case BO_LOr: {
16240 ICEDiag LHSResult = CheckICE(Exp->getLHS(), Ctx);
16241 ICEDiag RHSResult = CheckICE(Exp->getRHS(), Ctx);
16242 if (LHSResult.Kind == IK_ICE && RHSResult.Kind == IK_ICEIfUnevaluated) {
16243 // Rare case where the RHS has a comma "side-effect"; we need
16244 // to actually check the condition to see whether the side
16245 // with the comma is evaluated.
16246 if ((Exp->getOpcode() == BO_LAnd) !=
16247 (Exp->getLHS()->EvaluateKnownConstInt(Ctx) == 0))
16248 return RHSResult;
16249 return NoDiag();
16250 }
16251
16252 return Worst(LHSResult, RHSResult);
16253 }
16254 }
16255 llvm_unreachable("invalid binary operator kind");
16256 }
16257 case Expr::ImplicitCastExprClass:
16258 case Expr::CStyleCastExprClass:
16259 case Expr::CXXFunctionalCastExprClass:
16260 case Expr::CXXStaticCastExprClass:
16261 case Expr::CXXReinterpretCastExprClass:
16262 case Expr::CXXConstCastExprClass:
16263 case Expr::ObjCBridgedCastExprClass: {
16264 const Expr *SubExpr = cast<CastExpr>(E)->getSubExpr();
16265 if (isa<ExplicitCastExpr>(E)) {
16266 if (const FloatingLiteral *FL
16267 = dyn_cast<FloatingLiteral>(SubExpr->IgnoreParenImpCasts())) {
16268 unsigned DestWidth = Ctx.getIntWidth(E->getType());
16269 bool DestSigned = E->getType()->isSignedIntegerOrEnumerationType();
16270 APSInt IgnoredVal(DestWidth, !DestSigned);
16271 bool Ignored;
16272 // If the value does not fit in the destination type, the behavior is
16273 // undefined, so we are not required to treat it as a constant
16274 // expression.
16275 if (FL->getValue().convertToInteger(IgnoredVal,
16276 llvm::APFloat::rmTowardZero,
16277 &Ignored) & APFloat::opInvalidOp)
16278 return ICEDiag(IK_NotICE, E->getBeginLoc());
16279 return NoDiag();
16280 }
16281 }
16282 switch (cast<CastExpr>(E)->getCastKind()) {
16283 case CK_LValueToRValue:
16284 case CK_AtomicToNonAtomic:
16285 case CK_NonAtomicToAtomic:
16286 case CK_NoOp:
16287 case CK_IntegralToBoolean:
16288 case CK_IntegralCast:
16289 return CheckICE(SubExpr, Ctx);
16290 default:
16291 return ICEDiag(IK_NotICE, E->getBeginLoc());
16292 }
16293 }
16294 case Expr::BinaryConditionalOperatorClass: {
16295 const BinaryConditionalOperator *Exp = cast<BinaryConditionalOperator>(E);
16296 ICEDiag CommonResult = CheckICE(Exp->getCommon(), Ctx);
16297 if (CommonResult.Kind == IK_NotICE) return CommonResult;
16298 ICEDiag FalseResult = CheckICE(Exp->getFalseExpr(), Ctx);
16299 if (FalseResult.Kind == IK_NotICE) return FalseResult;
16300 if (CommonResult.Kind == IK_ICEIfUnevaluated) return CommonResult;
16301 if (FalseResult.Kind == IK_ICEIfUnevaluated &&
16302 Exp->getCommon()->EvaluateKnownConstInt(Ctx) != 0) return NoDiag();
16303 return FalseResult;
16304 }
16305 case Expr::ConditionalOperatorClass: {
16306 const ConditionalOperator *Exp = cast<ConditionalOperator>(E);
16307 // If the condition (ignoring parens) is a __builtin_constant_p call,
16308 // then only the true side is actually considered in an integer constant
16309 // expression, and it is fully evaluated. This is an important GNU
16310 // extension. See GCC PR38377 for discussion.
16311 if (const CallExpr *CallCE
16312 = dyn_cast<CallExpr>(Exp->getCond()->IgnoreParenCasts()))
16313 if (CallCE->getBuiltinCallee() == Builtin::BI__builtin_constant_p)
16314 return CheckEvalInICE(E, Ctx);
16315 ICEDiag CondResult = CheckICE(Exp->getCond(), Ctx);
16316 if (CondResult.Kind == IK_NotICE)
16317 return CondResult;
16318
16319 ICEDiag TrueResult = CheckICE(Exp->getTrueExpr(), Ctx);
16320 ICEDiag FalseResult = CheckICE(Exp->getFalseExpr(), Ctx);
16321
16322 if (TrueResult.Kind == IK_NotICE)
16323 return TrueResult;
16324 if (FalseResult.Kind == IK_NotICE)
16325 return FalseResult;
16326 if (CondResult.Kind == IK_ICEIfUnevaluated)
16327 return CondResult;
16328 if (TrueResult.Kind == IK_ICE && FalseResult.Kind == IK_ICE)
16329 return NoDiag();
16330 // Rare case where the diagnostics depend on which side is evaluated
16331 // Note that if we get here, CondResult is 0, and at least one of
16332 // TrueResult and FalseResult is non-zero.
16333 if (Exp->getCond()->EvaluateKnownConstInt(Ctx) == 0)
16334 return FalseResult;
16335 return TrueResult;
16336 }
16337 case Expr::CXXDefaultArgExprClass:
16338 return CheckICE(cast<CXXDefaultArgExpr>(E)->getExpr(), Ctx);
16339 case Expr::CXXDefaultInitExprClass:
16340 return CheckICE(cast<CXXDefaultInitExpr>(E)->getExpr(), Ctx);
16341 case Expr::ChooseExprClass: {
16342 return CheckICE(cast<ChooseExpr>(E)->getChosenSubExpr(), Ctx);
16343 }
16344 case Expr::BuiltinBitCastExprClass: {
16345 if (!checkBitCastConstexprEligibility(nullptr, Ctx, cast<CastExpr>(E)))
16346 return ICEDiag(IK_NotICE, E->getBeginLoc());
16347 return CheckICE(cast<CastExpr>(E)->getSubExpr(), Ctx);
16348 }
16349 }
16350
16351 llvm_unreachable("Invalid StmtClass!");
16352 }
16353
16354 /// Evaluate an expression as a C++11 integral constant expression.
EvaluateCPlusPlus11IntegralConstantExpr(const ASTContext & Ctx,const Expr * E,llvm::APSInt * Value,SourceLocation * Loc)16355 static bool EvaluateCPlusPlus11IntegralConstantExpr(const ASTContext &Ctx,
16356 const Expr *E,
16357 llvm::APSInt *Value,
16358 SourceLocation *Loc) {
16359 if (!E->getType()->isIntegralOrUnscopedEnumerationType()) {
16360 if (Loc) *Loc = E->getExprLoc();
16361 return false;
16362 }
16363
16364 APValue Result;
16365 if (!E->isCXX11ConstantExpr(Ctx, &Result, Loc))
16366 return false;
16367
16368 if (!Result.isInt()) {
16369 if (Loc) *Loc = E->getExprLoc();
16370 return false;
16371 }
16372
16373 if (Value) *Value = Result.getInt();
16374 return true;
16375 }
16376
isIntegerConstantExpr(const ASTContext & Ctx,SourceLocation * Loc) const16377 bool Expr::isIntegerConstantExpr(const ASTContext &Ctx,
16378 SourceLocation *Loc) const {
16379 assert(!isValueDependent() &&
16380 "Expression evaluator can't be called on a dependent expression.");
16381
16382 ExprTimeTraceScope TimeScope(this, Ctx, "isIntegerConstantExpr");
16383
16384 if (Ctx.getLangOpts().CPlusPlus11)
16385 return EvaluateCPlusPlus11IntegralConstantExpr(Ctx, this, nullptr, Loc);
16386
16387 ICEDiag D = CheckICE(this, Ctx);
16388 if (D.Kind != IK_ICE) {
16389 if (Loc) *Loc = D.Loc;
16390 return false;
16391 }
16392 return true;
16393 }
16394
16395 std::optional<llvm::APSInt>
getIntegerConstantExpr(const ASTContext & Ctx,SourceLocation * Loc) const16396 Expr::getIntegerConstantExpr(const ASTContext &Ctx, SourceLocation *Loc) const {
16397 if (isValueDependent()) {
16398 // Expression evaluator can't succeed on a dependent expression.
16399 return std::nullopt;
16400 }
16401
16402 APSInt Value;
16403
16404 if (Ctx.getLangOpts().CPlusPlus11) {
16405 if (EvaluateCPlusPlus11IntegralConstantExpr(Ctx, this, &Value, Loc))
16406 return Value;
16407 return std::nullopt;
16408 }
16409
16410 if (!isIntegerConstantExpr(Ctx, Loc))
16411 return std::nullopt;
16412
16413 // The only possible side-effects here are due to UB discovered in the
16414 // evaluation (for instance, INT_MAX + 1). In such a case, we are still
16415 // required to treat the expression as an ICE, so we produce the folded
16416 // value.
16417 EvalResult ExprResult;
16418 Expr::EvalStatus Status;
16419 EvalInfo Info(Ctx, Status, EvalInfo::EM_IgnoreSideEffects);
16420 Info.InConstantContext = true;
16421
16422 if (!::EvaluateAsInt(this, ExprResult, Ctx, SE_AllowSideEffects, Info))
16423 llvm_unreachable("ICE cannot be evaluated!");
16424
16425 return ExprResult.Val.getInt();
16426 }
16427
isCXX98IntegralConstantExpr(const ASTContext & Ctx) const16428 bool Expr::isCXX98IntegralConstantExpr(const ASTContext &Ctx) const {
16429 assert(!isValueDependent() &&
16430 "Expression evaluator can't be called on a dependent expression.");
16431
16432 return CheckICE(this, Ctx).Kind == IK_ICE;
16433 }
16434
isCXX11ConstantExpr(const ASTContext & Ctx,APValue * Result,SourceLocation * Loc) const16435 bool Expr::isCXX11ConstantExpr(const ASTContext &Ctx, APValue *Result,
16436 SourceLocation *Loc) const {
16437 assert(!isValueDependent() &&
16438 "Expression evaluator can't be called on a dependent expression.");
16439
16440 // We support this checking in C++98 mode in order to diagnose compatibility
16441 // issues.
16442 assert(Ctx.getLangOpts().CPlusPlus);
16443
16444 // Build evaluation settings.
16445 Expr::EvalStatus Status;
16446 SmallVector<PartialDiagnosticAt, 8> Diags;
16447 Status.Diag = &Diags;
16448 EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantExpression);
16449
16450 APValue Scratch;
16451 bool IsConstExpr =
16452 ::EvaluateAsRValue(Info, this, Result ? *Result : Scratch) &&
16453 // FIXME: We don't produce a diagnostic for this, but the callers that
16454 // call us on arbitrary full-expressions should generally not care.
16455 Info.discardCleanups() && !Status.HasSideEffects;
16456
16457 if (!Diags.empty()) {
16458 IsConstExpr = false;
16459 if (Loc) *Loc = Diags[0].first;
16460 } else if (!IsConstExpr) {
16461 // FIXME: This shouldn't happen.
16462 if (Loc) *Loc = getExprLoc();
16463 }
16464
16465 return IsConstExpr;
16466 }
16467
EvaluateWithSubstitution(APValue & Value,ASTContext & Ctx,const FunctionDecl * Callee,ArrayRef<const Expr * > Args,const Expr * This) const16468 bool Expr::EvaluateWithSubstitution(APValue &Value, ASTContext &Ctx,
16469 const FunctionDecl *Callee,
16470 ArrayRef<const Expr*> Args,
16471 const Expr *This) const {
16472 assert(!isValueDependent() &&
16473 "Expression evaluator can't be called on a dependent expression.");
16474
16475 llvm::TimeTraceScope TimeScope("EvaluateWithSubstitution", [&] {
16476 std::string Name;
16477 llvm::raw_string_ostream OS(Name);
16478 Callee->getNameForDiagnostic(OS, Ctx.getPrintingPolicy(),
16479 /*Qualified=*/true);
16480 return Name;
16481 });
16482
16483 Expr::EvalStatus Status;
16484 EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantExpressionUnevaluated);
16485 Info.InConstantContext = true;
16486
16487 LValue ThisVal;
16488 const LValue *ThisPtr = nullptr;
16489 if (This) {
16490 #ifndef NDEBUG
16491 auto *MD = dyn_cast<CXXMethodDecl>(Callee);
16492 assert(MD && "Don't provide `this` for non-methods.");
16493 assert(MD->isImplicitObjectMemberFunction() &&
16494 "Don't provide `this` for methods without an implicit object.");
16495 #endif
16496 if (!This->isValueDependent() &&
16497 EvaluateObjectArgument(Info, This, ThisVal) &&
16498 !Info.EvalStatus.HasSideEffects)
16499 ThisPtr = &ThisVal;
16500
16501 // Ignore any side-effects from a failed evaluation. This is safe because
16502 // they can't interfere with any other argument evaluation.
16503 Info.EvalStatus.HasSideEffects = false;
16504 }
16505
16506 CallRef Call = Info.CurrentCall->createCall(Callee);
16507 for (ArrayRef<const Expr*>::iterator I = Args.begin(), E = Args.end();
16508 I != E; ++I) {
16509 unsigned Idx = I - Args.begin();
16510 if (Idx >= Callee->getNumParams())
16511 break;
16512 const ParmVarDecl *PVD = Callee->getParamDecl(Idx);
16513 if ((*I)->isValueDependent() ||
16514 !EvaluateCallArg(PVD, *I, Call, Info) ||
16515 Info.EvalStatus.HasSideEffects) {
16516 // If evaluation fails, throw away the argument entirely.
16517 if (APValue *Slot = Info.getParamSlot(Call, PVD))
16518 *Slot = APValue();
16519 }
16520
16521 // Ignore any side-effects from a failed evaluation. This is safe because
16522 // they can't interfere with any other argument evaluation.
16523 Info.EvalStatus.HasSideEffects = false;
16524 }
16525
16526 // Parameter cleanups happen in the caller and are not part of this
16527 // evaluation.
16528 Info.discardCleanups();
16529 Info.EvalStatus.HasSideEffects = false;
16530
16531 // Build fake call to Callee.
16532 CallStackFrame Frame(Info, Callee->getLocation(), Callee, ThisPtr, This,
16533 Call);
16534 // FIXME: Missing ExprWithCleanups in enable_if conditions?
16535 FullExpressionRAII Scope(Info);
16536 return Evaluate(Value, Info, this) && Scope.destroy() &&
16537 !Info.EvalStatus.HasSideEffects;
16538 }
16539
isPotentialConstantExpr(const FunctionDecl * FD,SmallVectorImpl<PartialDiagnosticAt> & Diags)16540 bool Expr::isPotentialConstantExpr(const FunctionDecl *FD,
16541 SmallVectorImpl<
16542 PartialDiagnosticAt> &Diags) {
16543 // FIXME: It would be useful to check constexpr function templates, but at the
16544 // moment the constant expression evaluator cannot cope with the non-rigorous
16545 // ASTs which we build for dependent expressions.
16546 if (FD->isDependentContext())
16547 return true;
16548
16549 llvm::TimeTraceScope TimeScope("isPotentialConstantExpr", [&] {
16550 std::string Name;
16551 llvm::raw_string_ostream OS(Name);
16552 FD->getNameForDiagnostic(OS, FD->getASTContext().getPrintingPolicy(),
16553 /*Qualified=*/true);
16554 return Name;
16555 });
16556
16557 Expr::EvalStatus Status;
16558 Status.Diag = &Diags;
16559
16560 EvalInfo Info(FD->getASTContext(), Status, EvalInfo::EM_ConstantExpression);
16561 Info.InConstantContext = true;
16562 Info.CheckingPotentialConstantExpression = true;
16563
16564 // The constexpr VM attempts to compile all methods to bytecode here.
16565 if (Info.EnableNewConstInterp) {
16566 Info.Ctx.getInterpContext().isPotentialConstantExpr(Info, FD);
16567 return Diags.empty();
16568 }
16569
16570 const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD);
16571 const CXXRecordDecl *RD = MD ? MD->getParent()->getCanonicalDecl() : nullptr;
16572
16573 // Fabricate an arbitrary expression on the stack and pretend that it
16574 // is a temporary being used as the 'this' pointer.
16575 LValue This;
16576 ImplicitValueInitExpr VIE(RD ? Info.Ctx.getRecordType(RD) : Info.Ctx.IntTy);
16577 This.set({&VIE, Info.CurrentCall->Index});
16578
16579 ArrayRef<const Expr*> Args;
16580
16581 APValue Scratch;
16582 if (const CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(FD)) {
16583 // Evaluate the call as a constant initializer, to allow the construction
16584 // of objects of non-literal types.
16585 Info.setEvaluatingDecl(This.getLValueBase(), Scratch);
16586 HandleConstructorCall(&VIE, This, Args, CD, Info, Scratch);
16587 } else {
16588 SourceLocation Loc = FD->getLocation();
16589 HandleFunctionCall(
16590 Loc, FD, (MD && MD->isImplicitObjectMemberFunction()) ? &This : nullptr,
16591 &VIE, Args, CallRef(), FD->getBody(), Info, Scratch,
16592 /*ResultSlot=*/nullptr);
16593 }
16594
16595 return Diags.empty();
16596 }
16597
isPotentialConstantExprUnevaluated(Expr * E,const FunctionDecl * FD,SmallVectorImpl<PartialDiagnosticAt> & Diags)16598 bool Expr::isPotentialConstantExprUnevaluated(Expr *E,
16599 const FunctionDecl *FD,
16600 SmallVectorImpl<
16601 PartialDiagnosticAt> &Diags) {
16602 assert(!E->isValueDependent() &&
16603 "Expression evaluator can't be called on a dependent expression.");
16604
16605 Expr::EvalStatus Status;
16606 Status.Diag = &Diags;
16607
16608 EvalInfo Info(FD->getASTContext(), Status,
16609 EvalInfo::EM_ConstantExpressionUnevaluated);
16610 Info.InConstantContext = true;
16611 Info.CheckingPotentialConstantExpression = true;
16612
16613 // Fabricate a call stack frame to give the arguments a plausible cover story.
16614 CallStackFrame Frame(Info, SourceLocation(), FD, /*This=*/nullptr,
16615 /*CallExpr=*/nullptr, CallRef());
16616
16617 APValue ResultScratch;
16618 Evaluate(ResultScratch, Info, E);
16619 return Diags.empty();
16620 }
16621
tryEvaluateObjectSize(uint64_t & Result,ASTContext & Ctx,unsigned Type) const16622 bool Expr::tryEvaluateObjectSize(uint64_t &Result, ASTContext &Ctx,
16623 unsigned Type) const {
16624 if (!getType()->isPointerType())
16625 return false;
16626
16627 Expr::EvalStatus Status;
16628 EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantFold);
16629 return tryEvaluateBuiltinObjectSize(this, Type, Info, Result);
16630 }
16631
EvaluateBuiltinStrLen(const Expr * E,uint64_t & Result,EvalInfo & Info)16632 static bool EvaluateBuiltinStrLen(const Expr *E, uint64_t &Result,
16633 EvalInfo &Info) {
16634 if (!E->getType()->hasPointerRepresentation() || !E->isPRValue())
16635 return false;
16636
16637 LValue String;
16638
16639 if (!EvaluatePointer(E, String, Info))
16640 return false;
16641
16642 QualType CharTy = E->getType()->getPointeeType();
16643
16644 // Fast path: if it's a string literal, search the string value.
16645 if (const StringLiteral *S = dyn_cast_or_null<StringLiteral>(
16646 String.getLValueBase().dyn_cast<const Expr *>())) {
16647 StringRef Str = S->getBytes();
16648 int64_t Off = String.Offset.getQuantity();
16649 if (Off >= 0 && (uint64_t)Off <= (uint64_t)Str.size() &&
16650 S->getCharByteWidth() == 1 &&
16651 // FIXME: Add fast-path for wchar_t too.
16652 Info.Ctx.hasSameUnqualifiedType(CharTy, Info.Ctx.CharTy)) {
16653 Str = Str.substr(Off);
16654
16655 StringRef::size_type Pos = Str.find(0);
16656 if (Pos != StringRef::npos)
16657 Str = Str.substr(0, Pos);
16658
16659 Result = Str.size();
16660 return true;
16661 }
16662
16663 // Fall through to slow path.
16664 }
16665
16666 // Slow path: scan the bytes of the string looking for the terminating 0.
16667 for (uint64_t Strlen = 0; /**/; ++Strlen) {
16668 APValue Char;
16669 if (!handleLValueToRValueConversion(Info, E, CharTy, String, Char) ||
16670 !Char.isInt())
16671 return false;
16672 if (!Char.getInt()) {
16673 Result = Strlen;
16674 return true;
16675 }
16676 if (!HandleLValueArrayAdjustment(Info, E, String, CharTy, 1))
16677 return false;
16678 }
16679 }
16680
EvaluateCharRangeAsString(std::string & Result,const Expr * SizeExpression,const Expr * PtrExpression,ASTContext & Ctx,EvalResult & Status) const16681 bool Expr::EvaluateCharRangeAsString(std::string &Result,
16682 const Expr *SizeExpression,
16683 const Expr *PtrExpression, ASTContext &Ctx,
16684 EvalResult &Status) const {
16685 LValue String;
16686 EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantExpression);
16687 Info.InConstantContext = true;
16688
16689 FullExpressionRAII Scope(Info);
16690 APSInt SizeValue;
16691 if (!::EvaluateInteger(SizeExpression, SizeValue, Info))
16692 return false;
16693
16694 int64_t Size = SizeValue.getExtValue();
16695
16696 if (!::EvaluatePointer(PtrExpression, String, Info))
16697 return false;
16698
16699 QualType CharTy = PtrExpression->getType()->getPointeeType();
16700 for (int64_t I = 0; I < Size; ++I) {
16701 APValue Char;
16702 if (!handleLValueToRValueConversion(Info, PtrExpression, CharTy, String,
16703 Char))
16704 return false;
16705
16706 APSInt C = Char.getInt();
16707 Result.push_back(static_cast<char>(C.getExtValue()));
16708 if (!HandleLValueArrayAdjustment(Info, PtrExpression, String, CharTy, 1))
16709 return false;
16710 }
16711 if (!Scope.destroy())
16712 return false;
16713
16714 if (!CheckMemoryLeaks(Info))
16715 return false;
16716
16717 return true;
16718 }
16719
tryEvaluateStrLen(uint64_t & Result,ASTContext & Ctx) const16720 bool Expr::tryEvaluateStrLen(uint64_t &Result, ASTContext &Ctx) const {
16721 Expr::EvalStatus Status;
16722 EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantFold);
16723 return EvaluateBuiltinStrLen(this, Result, Info);
16724 }
16725