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 "Interp/Context.h"
36 #include "Interp/Frame.h"
37 #include "Interp/State.h"
38 #include "clang/AST/APValue.h"
39 #include "clang/AST/ASTContext.h"
40 #include "clang/AST/ASTDiagnostic.h"
41 #include "clang/AST/ASTLambda.h"
42 #include "clang/AST/Attr.h"
43 #include "clang/AST/CXXInheritance.h"
44 #include "clang/AST/CharUnits.h"
45 #include "clang/AST/CurrentSourceLocExprScope.h"
46 #include "clang/AST/Expr.h"
47 #include "clang/AST/OSLog.h"
48 #include "clang/AST/OptionalDiagnostic.h"
49 #include "clang/AST/RecordLayout.h"
50 #include "clang/AST/StmtVisitor.h"
51 #include "clang/AST/TypeLoc.h"
52 #include "clang/Basic/Builtins.h"
53 #include "clang/Basic/TargetInfo.h"
54 #include "llvm/ADT/APFixedPoint.h"
55 #include "llvm/ADT/Optional.h"
56 #include "llvm/ADT/SmallBitVector.h"
57 #include "llvm/Support/Debug.h"
58 #include "llvm/Support/SaveAndRestore.h"
59 #include "llvm/Support/raw_ostream.h"
60 #include <cstring>
61 #include <functional>
62
63 #define DEBUG_TYPE "exprconstant"
64
65 using namespace clang;
66 using llvm::APFixedPoint;
67 using llvm::APInt;
68 using llvm::APSInt;
69 using llvm::APFloat;
70 using llvm::FixedPointSemantics;
71 using llvm::Optional;
72
73 namespace {
74 struct LValue;
75 class CallStackFrame;
76 class EvalInfo;
77
78 using SourceLocExprScopeGuard =
79 CurrentSourceLocExprScope::SourceLocExprScopeGuard;
80
getType(APValue::LValueBase B)81 static QualType getType(APValue::LValueBase B) {
82 return B.getType();
83 }
84
85 /// Get an LValue path entry, which is known to not be an array index, as a
86 /// field declaration.
getAsField(APValue::LValuePathEntry E)87 static const FieldDecl *getAsField(APValue::LValuePathEntry E) {
88 return dyn_cast_or_null<FieldDecl>(E.getAsBaseOrMember().getPointer());
89 }
90 /// Get an LValue path entry, which is known to not be an array index, as a
91 /// base class declaration.
getAsBaseClass(APValue::LValuePathEntry E)92 static const CXXRecordDecl *getAsBaseClass(APValue::LValuePathEntry E) {
93 return dyn_cast_or_null<CXXRecordDecl>(E.getAsBaseOrMember().getPointer());
94 }
95 /// Determine whether this LValue path entry for a base class names a virtual
96 /// base class.
isVirtualBaseClass(APValue::LValuePathEntry E)97 static bool isVirtualBaseClass(APValue::LValuePathEntry E) {
98 return E.getAsBaseOrMember().getInt();
99 }
100
101 /// Given an expression, determine the type used to store the result of
102 /// evaluating that expression.
getStorageType(const ASTContext & Ctx,const Expr * E)103 static QualType getStorageType(const ASTContext &Ctx, const Expr *E) {
104 if (E->isPRValue())
105 return E->getType();
106 return Ctx.getLValueReferenceType(E->getType());
107 }
108
109 /// Given a CallExpr, try to get the alloc_size attribute. May return null.
getAllocSizeAttr(const CallExpr * CE)110 static const AllocSizeAttr *getAllocSizeAttr(const CallExpr *CE) {
111 if (const FunctionDecl *DirectCallee = CE->getDirectCallee())
112 return DirectCallee->getAttr<AllocSizeAttr>();
113 if (const Decl *IndirectCallee = CE->getCalleeDecl())
114 return IndirectCallee->getAttr<AllocSizeAttr>();
115 return nullptr;
116 }
117
118 /// Attempts to unwrap a CallExpr (with an alloc_size attribute) from an Expr.
119 /// This will look through a single cast.
120 ///
121 /// Returns null if we couldn't unwrap a function with alloc_size.
tryUnwrapAllocSizeCall(const Expr * E)122 static const CallExpr *tryUnwrapAllocSizeCall(const Expr *E) {
123 if (!E->getType()->isPointerType())
124 return nullptr;
125
126 E = E->IgnoreParens();
127 // If we're doing a variable assignment from e.g. malloc(N), there will
128 // probably be a cast of some kind. In exotic cases, we might also see a
129 // top-level ExprWithCleanups. Ignore them either way.
130 if (const auto *FE = dyn_cast<FullExpr>(E))
131 E = FE->getSubExpr()->IgnoreParens();
132
133 if (const auto *Cast = dyn_cast<CastExpr>(E))
134 E = Cast->getSubExpr()->IgnoreParens();
135
136 if (const auto *CE = dyn_cast<CallExpr>(E))
137 return getAllocSizeAttr(CE) ? CE : nullptr;
138 return nullptr;
139 }
140
141 /// Determines whether or not the given Base contains a call to a function
142 /// with the alloc_size attribute.
isBaseAnAllocSizeCall(APValue::LValueBase Base)143 static bool isBaseAnAllocSizeCall(APValue::LValueBase Base) {
144 const auto *E = Base.dyn_cast<const Expr *>();
145 return E && E->getType()->isPointerType() && tryUnwrapAllocSizeCall(E);
146 }
147
148 /// Determines whether the given kind of constant expression is only ever
149 /// used for name mangling. If so, it's permitted to reference things that we
150 /// can't generate code for (in particular, dllimported functions).
isForManglingOnly(ConstantExprKind Kind)151 static bool isForManglingOnly(ConstantExprKind Kind) {
152 switch (Kind) {
153 case ConstantExprKind::Normal:
154 case ConstantExprKind::ClassTemplateArgument:
155 case ConstantExprKind::ImmediateInvocation:
156 // Note that non-type template arguments of class type are emitted as
157 // template parameter objects.
158 return false;
159
160 case ConstantExprKind::NonClassTemplateArgument:
161 return true;
162 }
163 llvm_unreachable("unknown ConstantExprKind");
164 }
165
isTemplateArgument(ConstantExprKind Kind)166 static bool isTemplateArgument(ConstantExprKind Kind) {
167 switch (Kind) {
168 case ConstantExprKind::Normal:
169 case ConstantExprKind::ImmediateInvocation:
170 return false;
171
172 case ConstantExprKind::ClassTemplateArgument:
173 case ConstantExprKind::NonClassTemplateArgument:
174 return true;
175 }
176 llvm_unreachable("unknown ConstantExprKind");
177 }
178
179 /// The bound to claim that an array of unknown bound has.
180 /// The value in MostDerivedArraySize is undefined in this case. So, set it
181 /// to an arbitrary value that's likely to loudly break things if it's used.
182 static const uint64_t AssumedSizeForUnsizedArray =
183 std::numeric_limits<uint64_t>::max() / 2;
184
185 /// Determines if an LValue with the given LValueBase will have an unsized
186 /// array in its designator.
187 /// Find the path length and type of the most-derived subobject in the given
188 /// path, and find the size of the containing array, if any.
189 static unsigned
findMostDerivedSubobject(ASTContext & Ctx,APValue::LValueBase Base,ArrayRef<APValue::LValuePathEntry> Path,uint64_t & ArraySize,QualType & Type,bool & IsArray,bool & FirstEntryIsUnsizedArray)190 findMostDerivedSubobject(ASTContext &Ctx, APValue::LValueBase Base,
191 ArrayRef<APValue::LValuePathEntry> Path,
192 uint64_t &ArraySize, QualType &Type, bool &IsArray,
193 bool &FirstEntryIsUnsizedArray) {
194 // This only accepts LValueBases from APValues, and APValues don't support
195 // arrays that lack size info.
196 assert(!isBaseAnAllocSizeCall(Base) &&
197 "Unsized arrays shouldn't appear here");
198 unsigned MostDerivedLength = 0;
199 Type = getType(Base);
200
201 for (unsigned I = 0, N = Path.size(); I != N; ++I) {
202 if (Type->isArrayType()) {
203 const ArrayType *AT = Ctx.getAsArrayType(Type);
204 Type = AT->getElementType();
205 MostDerivedLength = I + 1;
206 IsArray = true;
207
208 if (auto *CAT = dyn_cast<ConstantArrayType>(AT)) {
209 ArraySize = CAT->getSize().getZExtValue();
210 } else {
211 assert(I == 0 && "unexpected unsized array designator");
212 FirstEntryIsUnsizedArray = true;
213 ArraySize = AssumedSizeForUnsizedArray;
214 }
215 } else if (Type->isAnyComplexType()) {
216 const ComplexType *CT = Type->castAs<ComplexType>();
217 Type = CT->getElementType();
218 ArraySize = 2;
219 MostDerivedLength = I + 1;
220 IsArray = true;
221 } else if (const FieldDecl *FD = getAsField(Path[I])) {
222 Type = FD->getType();
223 ArraySize = 0;
224 MostDerivedLength = I + 1;
225 IsArray = false;
226 } else {
227 // Path[I] describes a base class.
228 ArraySize = 0;
229 IsArray = false;
230 }
231 }
232 return MostDerivedLength;
233 }
234
235 /// A path from a glvalue to a subobject of that glvalue.
236 struct SubobjectDesignator {
237 /// True if the subobject was named in a manner not supported by C++11. Such
238 /// lvalues can still be folded, but they are not core constant expressions
239 /// and we cannot perform lvalue-to-rvalue conversions on them.
240 unsigned Invalid : 1;
241
242 /// Is this a pointer one past the end of an object?
243 unsigned IsOnePastTheEnd : 1;
244
245 /// Indicator of whether the first entry is an unsized array.
246 unsigned FirstEntryIsAnUnsizedArray : 1;
247
248 /// Indicator of whether the most-derived object is an array element.
249 unsigned MostDerivedIsArrayElement : 1;
250
251 /// The length of the path to the most-derived object of which this is a
252 /// subobject.
253 unsigned MostDerivedPathLength : 28;
254
255 /// The size of the array of which the most-derived object is an element.
256 /// This will always be 0 if the most-derived object is not an array
257 /// element. 0 is not an indicator of whether or not the most-derived object
258 /// is an array, however, because 0-length arrays are allowed.
259 ///
260 /// If the current array is an unsized array, the value of this is
261 /// undefined.
262 uint64_t MostDerivedArraySize;
263
264 /// The type of the most derived object referred to by this address.
265 QualType MostDerivedType;
266
267 typedef APValue::LValuePathEntry PathEntry;
268
269 /// The entries on the path from the glvalue to the designated subobject.
270 SmallVector<PathEntry, 8> Entries;
271
SubobjectDesignator__anon4a4db2530111::SubobjectDesignator272 SubobjectDesignator() : Invalid(true) {}
273
SubobjectDesignator__anon4a4db2530111::SubobjectDesignator274 explicit SubobjectDesignator(QualType T)
275 : Invalid(false), IsOnePastTheEnd(false),
276 FirstEntryIsAnUnsizedArray(false), MostDerivedIsArrayElement(false),
277 MostDerivedPathLength(0), MostDerivedArraySize(0),
278 MostDerivedType(T) {}
279
SubobjectDesignator__anon4a4db2530111::SubobjectDesignator280 SubobjectDesignator(ASTContext &Ctx, const APValue &V)
281 : Invalid(!V.isLValue() || !V.hasLValuePath()), IsOnePastTheEnd(false),
282 FirstEntryIsAnUnsizedArray(false), MostDerivedIsArrayElement(false),
283 MostDerivedPathLength(0), MostDerivedArraySize(0) {
284 assert(V.isLValue() && "Non-LValue used to make an LValue designator?");
285 if (!Invalid) {
286 IsOnePastTheEnd = V.isLValueOnePastTheEnd();
287 ArrayRef<PathEntry> VEntries = V.getLValuePath();
288 Entries.insert(Entries.end(), VEntries.begin(), VEntries.end());
289 if (V.getLValueBase()) {
290 bool IsArray = false;
291 bool FirstIsUnsizedArray = false;
292 MostDerivedPathLength = findMostDerivedSubobject(
293 Ctx, V.getLValueBase(), V.getLValuePath(), MostDerivedArraySize,
294 MostDerivedType, IsArray, FirstIsUnsizedArray);
295 MostDerivedIsArrayElement = IsArray;
296 FirstEntryIsAnUnsizedArray = FirstIsUnsizedArray;
297 }
298 }
299 }
300
truncate__anon4a4db2530111::SubobjectDesignator301 void truncate(ASTContext &Ctx, APValue::LValueBase Base,
302 unsigned NewLength) {
303 if (Invalid)
304 return;
305
306 assert(Base && "cannot truncate path for null pointer");
307 assert(NewLength <= Entries.size() && "not a truncation");
308
309 if (NewLength == Entries.size())
310 return;
311 Entries.resize(NewLength);
312
313 bool IsArray = false;
314 bool FirstIsUnsizedArray = false;
315 MostDerivedPathLength = findMostDerivedSubobject(
316 Ctx, Base, Entries, MostDerivedArraySize, MostDerivedType, IsArray,
317 FirstIsUnsizedArray);
318 MostDerivedIsArrayElement = IsArray;
319 FirstEntryIsAnUnsizedArray = FirstIsUnsizedArray;
320 }
321
setInvalid__anon4a4db2530111::SubobjectDesignator322 void setInvalid() {
323 Invalid = true;
324 Entries.clear();
325 }
326
327 /// Determine whether the most derived subobject is an array without a
328 /// known bound.
isMostDerivedAnUnsizedArray__anon4a4db2530111::SubobjectDesignator329 bool isMostDerivedAnUnsizedArray() const {
330 assert(!Invalid && "Calling this makes no sense on invalid designators");
331 return Entries.size() == 1 && FirstEntryIsAnUnsizedArray;
332 }
333
334 /// Determine what the most derived array's size is. Results in an assertion
335 /// failure if the most derived array lacks a size.
getMostDerivedArraySize__anon4a4db2530111::SubobjectDesignator336 uint64_t getMostDerivedArraySize() const {
337 assert(!isMostDerivedAnUnsizedArray() && "Unsized array has no size");
338 return MostDerivedArraySize;
339 }
340
341 /// Determine whether this is a one-past-the-end pointer.
isOnePastTheEnd__anon4a4db2530111::SubobjectDesignator342 bool isOnePastTheEnd() const {
343 assert(!Invalid);
344 if (IsOnePastTheEnd)
345 return true;
346 if (!isMostDerivedAnUnsizedArray() && MostDerivedIsArrayElement &&
347 Entries[MostDerivedPathLength - 1].getAsArrayIndex() ==
348 MostDerivedArraySize)
349 return true;
350 return false;
351 }
352
353 /// Get the range of valid index adjustments in the form
354 /// {maximum value that can be subtracted from this pointer,
355 /// maximum value that can be added to this pointer}
validIndexAdjustments__anon4a4db2530111::SubobjectDesignator356 std::pair<uint64_t, uint64_t> validIndexAdjustments() {
357 if (Invalid || isMostDerivedAnUnsizedArray())
358 return {0, 0};
359
360 // [expr.add]p4: For the purposes of these operators, a pointer to a
361 // nonarray object behaves the same as a pointer to the first element of
362 // an array of length one with the type of the object as its element type.
363 bool IsArray = MostDerivedPathLength == Entries.size() &&
364 MostDerivedIsArrayElement;
365 uint64_t ArrayIndex = IsArray ? Entries.back().getAsArrayIndex()
366 : (uint64_t)IsOnePastTheEnd;
367 uint64_t ArraySize =
368 IsArray ? getMostDerivedArraySize() : (uint64_t)1;
369 return {ArrayIndex, ArraySize - ArrayIndex};
370 }
371
372 /// Check that this refers to a valid subobject.
isValidSubobject__anon4a4db2530111::SubobjectDesignator373 bool isValidSubobject() const {
374 if (Invalid)
375 return false;
376 return !isOnePastTheEnd();
377 }
378 /// Check that this refers to a valid subobject, and if not, produce a
379 /// relevant diagnostic and set the designator as invalid.
380 bool checkSubobject(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK);
381
382 /// Get the type of the designated object.
getType__anon4a4db2530111::SubobjectDesignator383 QualType getType(ASTContext &Ctx) const {
384 assert(!Invalid && "invalid designator has no subobject type");
385 return MostDerivedPathLength == Entries.size()
386 ? MostDerivedType
387 : Ctx.getRecordType(getAsBaseClass(Entries.back()));
388 }
389
390 /// Update this designator to refer to the first element within this array.
addArrayUnchecked__anon4a4db2530111::SubobjectDesignator391 void addArrayUnchecked(const ConstantArrayType *CAT) {
392 Entries.push_back(PathEntry::ArrayIndex(0));
393
394 // This is a most-derived object.
395 MostDerivedType = CAT->getElementType();
396 MostDerivedIsArrayElement = true;
397 MostDerivedArraySize = CAT->getSize().getZExtValue();
398 MostDerivedPathLength = Entries.size();
399 }
400 /// Update this designator to refer to the first element within the array of
401 /// elements of type T. This is an array of unknown size.
addUnsizedArrayUnchecked__anon4a4db2530111::SubobjectDesignator402 void addUnsizedArrayUnchecked(QualType ElemTy) {
403 Entries.push_back(PathEntry::ArrayIndex(0));
404
405 MostDerivedType = ElemTy;
406 MostDerivedIsArrayElement = true;
407 // The value in MostDerivedArraySize is undefined in this case. So, set it
408 // to an arbitrary value that's likely to loudly break things if it's
409 // used.
410 MostDerivedArraySize = AssumedSizeForUnsizedArray;
411 MostDerivedPathLength = Entries.size();
412 }
413 /// Update this designator to refer to the given base or member of this
414 /// object.
addDeclUnchecked__anon4a4db2530111::SubobjectDesignator415 void addDeclUnchecked(const Decl *D, bool Virtual = false) {
416 Entries.push_back(APValue::BaseOrMemberType(D, Virtual));
417
418 // If this isn't a base class, it's a new most-derived object.
419 if (const FieldDecl *FD = dyn_cast<FieldDecl>(D)) {
420 MostDerivedType = FD->getType();
421 MostDerivedIsArrayElement = false;
422 MostDerivedArraySize = 0;
423 MostDerivedPathLength = Entries.size();
424 }
425 }
426 /// Update this designator to refer to the given complex component.
addComplexUnchecked__anon4a4db2530111::SubobjectDesignator427 void addComplexUnchecked(QualType EltTy, bool Imag) {
428 Entries.push_back(PathEntry::ArrayIndex(Imag));
429
430 // This is technically a most-derived object, though in practice this
431 // is unlikely to matter.
432 MostDerivedType = EltTy;
433 MostDerivedIsArrayElement = true;
434 MostDerivedArraySize = 2;
435 MostDerivedPathLength = Entries.size();
436 }
437 void diagnoseUnsizedArrayPointerArithmetic(EvalInfo &Info, const Expr *E);
438 void diagnosePointerArithmetic(EvalInfo &Info, const Expr *E,
439 const APSInt &N);
440 /// Add N to the address of this subobject.
adjustIndex__anon4a4db2530111::SubobjectDesignator441 void adjustIndex(EvalInfo &Info, const Expr *E, APSInt N) {
442 if (Invalid || !N) return;
443 uint64_t TruncatedN = N.extOrTrunc(64).getZExtValue();
444 if (isMostDerivedAnUnsizedArray()) {
445 diagnoseUnsizedArrayPointerArithmetic(Info, E);
446 // Can't verify -- trust that the user is doing the right thing (or if
447 // not, trust that the caller will catch the bad behavior).
448 // FIXME: Should we reject if this overflows, at least?
449 Entries.back() = PathEntry::ArrayIndex(
450 Entries.back().getAsArrayIndex() + TruncatedN);
451 return;
452 }
453
454 // [expr.add]p4: For the purposes of these operators, a pointer to a
455 // nonarray object behaves the same as a pointer to the first element of
456 // an array of length one with the type of the object as its element type.
457 bool IsArray = MostDerivedPathLength == Entries.size() &&
458 MostDerivedIsArrayElement;
459 uint64_t ArrayIndex = IsArray ? Entries.back().getAsArrayIndex()
460 : (uint64_t)IsOnePastTheEnd;
461 uint64_t ArraySize =
462 IsArray ? getMostDerivedArraySize() : (uint64_t)1;
463
464 if (N < -(int64_t)ArrayIndex || N > ArraySize - ArrayIndex) {
465 // Calculate the actual index in a wide enough type, so we can include
466 // it in the note.
467 N = N.extend(std::max<unsigned>(N.getBitWidth() + 1, 65));
468 (llvm::APInt&)N += ArrayIndex;
469 assert(N.ugt(ArraySize) && "bounds check failed for in-bounds index");
470 diagnosePointerArithmetic(Info, E, N);
471 setInvalid();
472 return;
473 }
474
475 ArrayIndex += TruncatedN;
476 assert(ArrayIndex <= ArraySize &&
477 "bounds check succeeded for out-of-bounds index");
478
479 if (IsArray)
480 Entries.back() = PathEntry::ArrayIndex(ArrayIndex);
481 else
482 IsOnePastTheEnd = (ArrayIndex != 0);
483 }
484 };
485
486 /// A scope at the end of which an object can need to be destroyed.
487 enum class ScopeKind {
488 Block,
489 FullExpression,
490 Call
491 };
492
493 /// A reference to a particular call and its arguments.
494 struct CallRef {
CallRef__anon4a4db2530111::CallRef495 CallRef() : OrigCallee(), CallIndex(0), Version() {}
CallRef__anon4a4db2530111::CallRef496 CallRef(const FunctionDecl *Callee, unsigned CallIndex, unsigned Version)
497 : OrigCallee(Callee), CallIndex(CallIndex), Version(Version) {}
498
operator bool__anon4a4db2530111::CallRef499 explicit operator bool() const { return OrigCallee; }
500
501 /// Get the parameter that the caller initialized, corresponding to the
502 /// given parameter in the callee.
getOrigParam__anon4a4db2530111::CallRef503 const ParmVarDecl *getOrigParam(const ParmVarDecl *PVD) const {
504 return OrigCallee ? OrigCallee->getParamDecl(PVD->getFunctionScopeIndex())
505 : PVD;
506 }
507
508 /// The callee at the point where the arguments were evaluated. This might
509 /// be different from the actual callee (a different redeclaration, or a
510 /// virtual override), but this function's parameters are the ones that
511 /// appear in the parameter map.
512 const FunctionDecl *OrigCallee;
513 /// The call index of the frame that holds the argument values.
514 unsigned CallIndex;
515 /// The version of the parameters corresponding to this call.
516 unsigned Version;
517 };
518
519 /// A stack frame in the constexpr call stack.
520 class CallStackFrame : public interp::Frame {
521 public:
522 EvalInfo &Info;
523
524 /// Parent - The caller of this stack frame.
525 CallStackFrame *Caller;
526
527 /// Callee - The function which was called.
528 const FunctionDecl *Callee;
529
530 /// This - The binding for the this pointer in this call, if any.
531 const LValue *This;
532
533 /// Information on how to find the arguments to this call. Our arguments
534 /// are stored in our parent's CallStackFrame, using the ParmVarDecl* as a
535 /// key and this value as the version.
536 CallRef Arguments;
537
538 /// Source location information about the default argument or default
539 /// initializer expression we're evaluating, if any.
540 CurrentSourceLocExprScope CurSourceLocExprScope;
541
542 // Note that we intentionally use std::map here so that references to
543 // values are stable.
544 typedef std::pair<const void *, unsigned> MapKeyTy;
545 typedef std::map<MapKeyTy, APValue> MapTy;
546 /// Temporaries - Temporary lvalues materialized within this stack frame.
547 MapTy Temporaries;
548
549 /// CallLoc - The location of the call expression for this call.
550 SourceLocation CallLoc;
551
552 /// Index - The call index of this call.
553 unsigned Index;
554
555 /// The stack of integers for tracking version numbers for temporaries.
556 SmallVector<unsigned, 2> TempVersionStack = {1};
557 unsigned CurTempVersion = TempVersionStack.back();
558
getTempVersion() const559 unsigned getTempVersion() const { return TempVersionStack.back(); }
560
pushTempVersion()561 void pushTempVersion() {
562 TempVersionStack.push_back(++CurTempVersion);
563 }
564
popTempVersion()565 void popTempVersion() {
566 TempVersionStack.pop_back();
567 }
568
createCall(const FunctionDecl * Callee)569 CallRef createCall(const FunctionDecl *Callee) {
570 return {Callee, Index, ++CurTempVersion};
571 }
572
573 // FIXME: Adding this to every 'CallStackFrame' may have a nontrivial impact
574 // on the overall stack usage of deeply-recursing constexpr evaluations.
575 // (We should cache this map rather than recomputing it repeatedly.)
576 // But let's try this and see how it goes; we can look into caching the map
577 // as a later change.
578
579 /// LambdaCaptureFields - Mapping from captured variables/this to
580 /// corresponding data members in the closure class.
581 llvm::DenseMap<const VarDecl *, FieldDecl *> LambdaCaptureFields;
582 FieldDecl *LambdaThisCaptureField;
583
584 CallStackFrame(EvalInfo &Info, SourceLocation CallLoc,
585 const FunctionDecl *Callee, const LValue *This,
586 CallRef Arguments);
587 ~CallStackFrame();
588
589 // Return the temporary for Key whose version number is Version.
getTemporary(const void * Key,unsigned Version)590 APValue *getTemporary(const void *Key, unsigned Version) {
591 MapKeyTy KV(Key, Version);
592 auto LB = Temporaries.lower_bound(KV);
593 if (LB != Temporaries.end() && LB->first == KV)
594 return &LB->second;
595 // Pair (Key,Version) wasn't found in the map. Check that no elements
596 // in the map have 'Key' as their key.
597 assert((LB == Temporaries.end() || LB->first.first != Key) &&
598 (LB == Temporaries.begin() || std::prev(LB)->first.first != Key) &&
599 "Element with key 'Key' found in map");
600 return nullptr;
601 }
602
603 // Return the current temporary for Key in the map.
getCurrentTemporary(const void * Key)604 APValue *getCurrentTemporary(const void *Key) {
605 auto UB = Temporaries.upper_bound(MapKeyTy(Key, UINT_MAX));
606 if (UB != Temporaries.begin() && std::prev(UB)->first.first == Key)
607 return &std::prev(UB)->second;
608 return nullptr;
609 }
610
611 // Return the version number of the current temporary for Key.
getCurrentTemporaryVersion(const void * Key) const612 unsigned getCurrentTemporaryVersion(const void *Key) const {
613 auto UB = Temporaries.upper_bound(MapKeyTy(Key, UINT_MAX));
614 if (UB != Temporaries.begin() && std::prev(UB)->first.first == Key)
615 return std::prev(UB)->first.second;
616 return 0;
617 }
618
619 /// Allocate storage for an object of type T in this stack frame.
620 /// Populates LV with a handle to the created object. Key identifies
621 /// the temporary within the stack frame, and must not be reused without
622 /// bumping the temporary version number.
623 template<typename KeyT>
624 APValue &createTemporary(const KeyT *Key, QualType T,
625 ScopeKind Scope, LValue &LV);
626
627 /// Allocate storage for a parameter of a function call made in this frame.
628 APValue &createParam(CallRef Args, const ParmVarDecl *PVD, LValue &LV);
629
630 void describe(llvm::raw_ostream &OS) override;
631
getCaller() const632 Frame *getCaller() const override { return Caller; }
getCallLocation() const633 SourceLocation getCallLocation() const override { return CallLoc; }
getCallee() const634 const FunctionDecl *getCallee() const override { return Callee; }
635
isStdFunction() const636 bool isStdFunction() const {
637 for (const DeclContext *DC = Callee; DC; DC = DC->getParent())
638 if (DC->isStdNamespace())
639 return true;
640 return false;
641 }
642
643 private:
644 APValue &createLocal(APValue::LValueBase Base, const void *Key, QualType T,
645 ScopeKind Scope);
646 };
647
648 /// Temporarily override 'this'.
649 class ThisOverrideRAII {
650 public:
ThisOverrideRAII(CallStackFrame & Frame,const LValue * NewThis,bool Enable)651 ThisOverrideRAII(CallStackFrame &Frame, const LValue *NewThis, bool Enable)
652 : Frame(Frame), OldThis(Frame.This) {
653 if (Enable)
654 Frame.This = NewThis;
655 }
~ThisOverrideRAII()656 ~ThisOverrideRAII() {
657 Frame.This = OldThis;
658 }
659 private:
660 CallStackFrame &Frame;
661 const LValue *OldThis;
662 };
663 }
664
665 static bool HandleDestruction(EvalInfo &Info, const Expr *E,
666 const LValue &This, QualType ThisType);
667 static bool HandleDestruction(EvalInfo &Info, SourceLocation Loc,
668 APValue::LValueBase LVBase, APValue &Value,
669 QualType T);
670
671 namespace {
672 /// A cleanup, and a flag indicating whether it is lifetime-extended.
673 class Cleanup {
674 llvm::PointerIntPair<APValue*, 2, ScopeKind> Value;
675 APValue::LValueBase Base;
676 QualType T;
677
678 public:
Cleanup(APValue * Val,APValue::LValueBase Base,QualType T,ScopeKind Scope)679 Cleanup(APValue *Val, APValue::LValueBase Base, QualType T,
680 ScopeKind Scope)
681 : Value(Val, Scope), Base(Base), T(T) {}
682
683 /// Determine whether this cleanup should be performed at the end of the
684 /// given kind of scope.
isDestroyedAtEndOf(ScopeKind K) const685 bool isDestroyedAtEndOf(ScopeKind K) const {
686 return (int)Value.getInt() >= (int)K;
687 }
endLifetime(EvalInfo & Info,bool RunDestructors)688 bool endLifetime(EvalInfo &Info, bool RunDestructors) {
689 if (RunDestructors) {
690 SourceLocation Loc;
691 if (const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>())
692 Loc = VD->getLocation();
693 else if (const Expr *E = Base.dyn_cast<const Expr*>())
694 Loc = E->getExprLoc();
695 return HandleDestruction(Info, Loc, Base, *Value.getPointer(), T);
696 }
697 *Value.getPointer() = APValue();
698 return true;
699 }
700
hasSideEffect()701 bool hasSideEffect() {
702 return T.isDestructedType();
703 }
704 };
705
706 /// A reference to an object whose construction we are currently evaluating.
707 struct ObjectUnderConstruction {
708 APValue::LValueBase Base;
709 ArrayRef<APValue::LValuePathEntry> Path;
operator ==(const ObjectUnderConstruction & LHS,const ObjectUnderConstruction & RHS)710 friend bool operator==(const ObjectUnderConstruction &LHS,
711 const ObjectUnderConstruction &RHS) {
712 return LHS.Base == RHS.Base && LHS.Path == RHS.Path;
713 }
hash_value(const ObjectUnderConstruction & Obj)714 friend llvm::hash_code hash_value(const ObjectUnderConstruction &Obj) {
715 return llvm::hash_combine(Obj.Base, Obj.Path);
716 }
717 };
718 enum class ConstructionPhase {
719 None,
720 Bases,
721 AfterBases,
722 AfterFields,
723 Destroying,
724 DestroyingBases
725 };
726 }
727
728 namespace llvm {
729 template<> struct DenseMapInfo<ObjectUnderConstruction> {
730 using Base = DenseMapInfo<APValue::LValueBase>;
getEmptyKeyllvm::DenseMapInfo731 static ObjectUnderConstruction getEmptyKey() {
732 return {Base::getEmptyKey(), {}}; }
getTombstoneKeyllvm::DenseMapInfo733 static ObjectUnderConstruction getTombstoneKey() {
734 return {Base::getTombstoneKey(), {}};
735 }
getHashValuellvm::DenseMapInfo736 static unsigned getHashValue(const ObjectUnderConstruction &Object) {
737 return hash_value(Object);
738 }
isEqualllvm::DenseMapInfo739 static bool isEqual(const ObjectUnderConstruction &LHS,
740 const ObjectUnderConstruction &RHS) {
741 return LHS == RHS;
742 }
743 };
744 }
745
746 namespace {
747 /// A dynamically-allocated heap object.
748 struct DynAlloc {
749 /// The value of this heap-allocated object.
750 APValue Value;
751 /// The allocating expression; used for diagnostics. Either a CXXNewExpr
752 /// or a CallExpr (the latter is for direct calls to operator new inside
753 /// std::allocator<T>::allocate).
754 const Expr *AllocExpr = nullptr;
755
756 enum Kind {
757 New,
758 ArrayNew,
759 StdAllocator
760 };
761
762 /// Get the kind of the allocation. This must match between allocation
763 /// and deallocation.
getKind__anon4a4db2530311::DynAlloc764 Kind getKind() const {
765 if (auto *NE = dyn_cast<CXXNewExpr>(AllocExpr))
766 return NE->isArray() ? ArrayNew : New;
767 assert(isa<CallExpr>(AllocExpr));
768 return StdAllocator;
769 }
770 };
771
772 struct DynAllocOrder {
operator ()__anon4a4db2530311::DynAllocOrder773 bool operator()(DynamicAllocLValue L, DynamicAllocLValue R) const {
774 return L.getIndex() < R.getIndex();
775 }
776 };
777
778 /// EvalInfo - This is a private struct used by the evaluator to capture
779 /// information about a subexpression as it is folded. It retains information
780 /// about the AST context, but also maintains information about the folded
781 /// expression.
782 ///
783 /// If an expression could be evaluated, it is still possible it is not a C
784 /// "integer constant expression" or constant expression. If not, this struct
785 /// captures information about how and why not.
786 ///
787 /// One bit of information passed *into* the request for constant folding
788 /// indicates whether the subexpression is "evaluated" or not according to C
789 /// rules. For example, the RHS of (0 && foo()) is not evaluated. We can
790 /// evaluate the expression regardless of what the RHS is, but C only allows
791 /// certain things in certain situations.
792 class EvalInfo : public interp::State {
793 public:
794 ASTContext &Ctx;
795
796 /// EvalStatus - Contains information about the evaluation.
797 Expr::EvalStatus &EvalStatus;
798
799 /// CurrentCall - The top of the constexpr call stack.
800 CallStackFrame *CurrentCall;
801
802 /// CallStackDepth - The number of calls in the call stack right now.
803 unsigned CallStackDepth;
804
805 /// NextCallIndex - The next call index to assign.
806 unsigned NextCallIndex;
807
808 /// StepsLeft - The remaining number of evaluation steps we're permitted
809 /// to perform. This is essentially a limit for the number of statements
810 /// we will evaluate.
811 unsigned StepsLeft;
812
813 /// Enable the experimental new constant interpreter. If an expression is
814 /// not supported by the interpreter, an error is triggered.
815 bool EnableNewConstInterp;
816
817 /// BottomFrame - The frame in which evaluation started. This must be
818 /// initialized after CurrentCall and CallStackDepth.
819 CallStackFrame BottomFrame;
820
821 /// A stack of values whose lifetimes end at the end of some surrounding
822 /// evaluation frame.
823 llvm::SmallVector<Cleanup, 16> CleanupStack;
824
825 /// EvaluatingDecl - This is the declaration whose initializer is being
826 /// evaluated, if any.
827 APValue::LValueBase EvaluatingDecl;
828
829 enum class EvaluatingDeclKind {
830 None,
831 /// We're evaluating the construction of EvaluatingDecl.
832 Ctor,
833 /// We're evaluating the destruction of EvaluatingDecl.
834 Dtor,
835 };
836 EvaluatingDeclKind IsEvaluatingDecl = EvaluatingDeclKind::None;
837
838 /// EvaluatingDeclValue - This is the value being constructed for the
839 /// declaration whose initializer is being evaluated, if any.
840 APValue *EvaluatingDeclValue;
841
842 /// Set of objects that are currently being constructed.
843 llvm::DenseMap<ObjectUnderConstruction, ConstructionPhase>
844 ObjectsUnderConstruction;
845
846 /// Current heap allocations, along with the location where each was
847 /// allocated. We use std::map here because we need stable addresses
848 /// for the stored APValues.
849 std::map<DynamicAllocLValue, DynAlloc, DynAllocOrder> HeapAllocs;
850
851 /// The number of heap allocations performed so far in this evaluation.
852 unsigned NumHeapAllocs = 0;
853
854 struct EvaluatingConstructorRAII {
855 EvalInfo &EI;
856 ObjectUnderConstruction Object;
857 bool DidInsert;
EvaluatingConstructorRAII__anon4a4db2530311::EvalInfo::EvaluatingConstructorRAII858 EvaluatingConstructorRAII(EvalInfo &EI, ObjectUnderConstruction Object,
859 bool HasBases)
860 : EI(EI), Object(Object) {
861 DidInsert =
862 EI.ObjectsUnderConstruction
863 .insert({Object, HasBases ? ConstructionPhase::Bases
864 : ConstructionPhase::AfterBases})
865 .second;
866 }
finishedConstructingBases__anon4a4db2530311::EvalInfo::EvaluatingConstructorRAII867 void finishedConstructingBases() {
868 EI.ObjectsUnderConstruction[Object] = ConstructionPhase::AfterBases;
869 }
finishedConstructingFields__anon4a4db2530311::EvalInfo::EvaluatingConstructorRAII870 void finishedConstructingFields() {
871 EI.ObjectsUnderConstruction[Object] = ConstructionPhase::AfterFields;
872 }
~EvaluatingConstructorRAII__anon4a4db2530311::EvalInfo::EvaluatingConstructorRAII873 ~EvaluatingConstructorRAII() {
874 if (DidInsert) EI.ObjectsUnderConstruction.erase(Object);
875 }
876 };
877
878 struct EvaluatingDestructorRAII {
879 EvalInfo &EI;
880 ObjectUnderConstruction Object;
881 bool DidInsert;
EvaluatingDestructorRAII__anon4a4db2530311::EvalInfo::EvaluatingDestructorRAII882 EvaluatingDestructorRAII(EvalInfo &EI, ObjectUnderConstruction Object)
883 : EI(EI), Object(Object) {
884 DidInsert = EI.ObjectsUnderConstruction
885 .insert({Object, ConstructionPhase::Destroying})
886 .second;
887 }
startedDestroyingBases__anon4a4db2530311::EvalInfo::EvaluatingDestructorRAII888 void startedDestroyingBases() {
889 EI.ObjectsUnderConstruction[Object] =
890 ConstructionPhase::DestroyingBases;
891 }
~EvaluatingDestructorRAII__anon4a4db2530311::EvalInfo::EvaluatingDestructorRAII892 ~EvaluatingDestructorRAII() {
893 if (DidInsert)
894 EI.ObjectsUnderConstruction.erase(Object);
895 }
896 };
897
898 ConstructionPhase
isEvaluatingCtorDtor(APValue::LValueBase Base,ArrayRef<APValue::LValuePathEntry> Path)899 isEvaluatingCtorDtor(APValue::LValueBase Base,
900 ArrayRef<APValue::LValuePathEntry> Path) {
901 return ObjectsUnderConstruction.lookup({Base, Path});
902 }
903
904 /// If we're currently speculatively evaluating, the outermost call stack
905 /// depth at which we can mutate state, otherwise 0.
906 unsigned SpeculativeEvaluationDepth = 0;
907
908 /// The current array initialization index, if we're performing array
909 /// initialization.
910 uint64_t ArrayInitIndex = -1;
911
912 /// HasActiveDiagnostic - Was the previous diagnostic stored? If so, further
913 /// notes attached to it will also be stored, otherwise they will not be.
914 bool HasActiveDiagnostic;
915
916 /// Have we emitted a diagnostic explaining why we couldn't constant
917 /// fold (not just why it's not strictly a constant expression)?
918 bool HasFoldFailureDiagnostic;
919
920 /// Whether or not we're in a context where the front end requires a
921 /// constant value.
922 bool InConstantContext;
923
924 /// Whether we're checking that an expression is a potential constant
925 /// expression. If so, do not fail on constructs that could become constant
926 /// later on (such as a use of an undefined global).
927 bool CheckingPotentialConstantExpression = false;
928
929 /// Whether we're checking for an expression that has undefined behavior.
930 /// If so, we will produce warnings if we encounter an operation that is
931 /// always undefined.
932 ///
933 /// Note that we still need to evaluate the expression normally when this
934 /// is set; this is used when evaluating ICEs in C.
935 bool CheckingForUndefinedBehavior = false;
936
937 enum EvaluationMode {
938 /// Evaluate as a constant expression. Stop if we find that the expression
939 /// is not a constant expression.
940 EM_ConstantExpression,
941
942 /// Evaluate as a constant expression. Stop if we find that the expression
943 /// is not a constant expression. Some expressions can be retried in the
944 /// optimizer if we don't constant fold them here, but in an unevaluated
945 /// context we try to fold them immediately since the optimizer never
946 /// gets a chance to look at it.
947 EM_ConstantExpressionUnevaluated,
948
949 /// Fold the expression to a constant. Stop if we hit a side-effect that
950 /// we can't model.
951 EM_ConstantFold,
952
953 /// Evaluate in any way we know how. Don't worry about side-effects that
954 /// can't be modeled.
955 EM_IgnoreSideEffects,
956 } EvalMode;
957
958 /// Are we checking whether the expression is a potential constant
959 /// expression?
checkingPotentialConstantExpression() const960 bool checkingPotentialConstantExpression() const override {
961 return CheckingPotentialConstantExpression;
962 }
963
964 /// Are we checking an expression for overflow?
965 // FIXME: We should check for any kind of undefined or suspicious behavior
966 // in such constructs, not just overflow.
checkingForUndefinedBehavior() const967 bool checkingForUndefinedBehavior() const override {
968 return CheckingForUndefinedBehavior;
969 }
970
EvalInfo(const ASTContext & C,Expr::EvalStatus & S,EvaluationMode Mode)971 EvalInfo(const ASTContext &C, Expr::EvalStatus &S, EvaluationMode Mode)
972 : Ctx(const_cast<ASTContext &>(C)), EvalStatus(S), CurrentCall(nullptr),
973 CallStackDepth(0), NextCallIndex(1),
974 StepsLeft(C.getLangOpts().ConstexprStepLimit),
975 EnableNewConstInterp(C.getLangOpts().EnableNewConstInterp),
976 BottomFrame(*this, SourceLocation(), nullptr, nullptr, CallRef()),
977 EvaluatingDecl((const ValueDecl *)nullptr),
978 EvaluatingDeclValue(nullptr), HasActiveDiagnostic(false),
979 HasFoldFailureDiagnostic(false), InConstantContext(false),
980 EvalMode(Mode) {}
981
~EvalInfo()982 ~EvalInfo() {
983 discardCleanups();
984 }
985
setEvaluatingDecl(APValue::LValueBase Base,APValue & Value,EvaluatingDeclKind EDK=EvaluatingDeclKind::Ctor)986 void setEvaluatingDecl(APValue::LValueBase Base, APValue &Value,
987 EvaluatingDeclKind EDK = EvaluatingDeclKind::Ctor) {
988 EvaluatingDecl = Base;
989 IsEvaluatingDecl = EDK;
990 EvaluatingDeclValue = &Value;
991 }
992
CheckCallLimit(SourceLocation Loc)993 bool CheckCallLimit(SourceLocation Loc) {
994 // Don't perform any constexpr calls (other than the call we're checking)
995 // when checking a potential constant expression.
996 if (checkingPotentialConstantExpression() && CallStackDepth > 1)
997 return false;
998 if (NextCallIndex == 0) {
999 // NextCallIndex has wrapped around.
1000 FFDiag(Loc, diag::note_constexpr_call_limit_exceeded);
1001 return false;
1002 }
1003 if (CallStackDepth <= getLangOpts().ConstexprCallDepth)
1004 return true;
1005 FFDiag(Loc, diag::note_constexpr_depth_limit_exceeded)
1006 << getLangOpts().ConstexprCallDepth;
1007 return false;
1008 }
1009
1010 std::pair<CallStackFrame *, unsigned>
getCallFrameAndDepth(unsigned CallIndex)1011 getCallFrameAndDepth(unsigned CallIndex) {
1012 assert(CallIndex && "no call index in getCallFrameAndDepth");
1013 // We will eventually hit BottomFrame, which has Index 1, so Frame can't
1014 // be null in this loop.
1015 unsigned Depth = CallStackDepth;
1016 CallStackFrame *Frame = CurrentCall;
1017 while (Frame->Index > CallIndex) {
1018 Frame = Frame->Caller;
1019 --Depth;
1020 }
1021 if (Frame->Index == CallIndex)
1022 return {Frame, Depth};
1023 return {nullptr, 0};
1024 }
1025
nextStep(const Stmt * S)1026 bool nextStep(const Stmt *S) {
1027 if (!StepsLeft) {
1028 FFDiag(S->getBeginLoc(), diag::note_constexpr_step_limit_exceeded);
1029 return false;
1030 }
1031 --StepsLeft;
1032 return true;
1033 }
1034
1035 APValue *createHeapAlloc(const Expr *E, QualType T, LValue &LV);
1036
lookupDynamicAlloc(DynamicAllocLValue DA)1037 Optional<DynAlloc*> lookupDynamicAlloc(DynamicAllocLValue DA) {
1038 Optional<DynAlloc*> Result;
1039 auto It = HeapAllocs.find(DA);
1040 if (It != HeapAllocs.end())
1041 Result = &It->second;
1042 return Result;
1043 }
1044
1045 /// Get the allocated storage for the given parameter of the given call.
getParamSlot(CallRef Call,const ParmVarDecl * PVD)1046 APValue *getParamSlot(CallRef Call, const ParmVarDecl *PVD) {
1047 CallStackFrame *Frame = getCallFrameAndDepth(Call.CallIndex).first;
1048 return Frame ? Frame->getTemporary(Call.getOrigParam(PVD), Call.Version)
1049 : nullptr;
1050 }
1051
1052 /// Information about a stack frame for std::allocator<T>::[de]allocate.
1053 struct StdAllocatorCaller {
1054 unsigned FrameIndex;
1055 QualType ElemType;
operator bool__anon4a4db2530311::EvalInfo::StdAllocatorCaller1056 explicit operator bool() const { return FrameIndex != 0; };
1057 };
1058
getStdAllocatorCaller(StringRef FnName) const1059 StdAllocatorCaller getStdAllocatorCaller(StringRef FnName) const {
1060 for (const CallStackFrame *Call = CurrentCall; Call != &BottomFrame;
1061 Call = Call->Caller) {
1062 const auto *MD = dyn_cast_or_null<CXXMethodDecl>(Call->Callee);
1063 if (!MD)
1064 continue;
1065 const IdentifierInfo *FnII = MD->getIdentifier();
1066 if (!FnII || !FnII->isStr(FnName))
1067 continue;
1068
1069 const auto *CTSD =
1070 dyn_cast<ClassTemplateSpecializationDecl>(MD->getParent());
1071 if (!CTSD)
1072 continue;
1073
1074 const IdentifierInfo *ClassII = CTSD->getIdentifier();
1075 const TemplateArgumentList &TAL = CTSD->getTemplateArgs();
1076 if (CTSD->isInStdNamespace() && ClassII &&
1077 ClassII->isStr("allocator") && TAL.size() >= 1 &&
1078 TAL[0].getKind() == TemplateArgument::Type)
1079 return {Call->Index, TAL[0].getAsType()};
1080 }
1081
1082 return {};
1083 }
1084
performLifetimeExtension()1085 void performLifetimeExtension() {
1086 // Disable the cleanups for lifetime-extended temporaries.
1087 CleanupStack.erase(std::remove_if(CleanupStack.begin(),
1088 CleanupStack.end(),
1089 [](Cleanup &C) {
1090 return !C.isDestroyedAtEndOf(
1091 ScopeKind::FullExpression);
1092 }),
1093 CleanupStack.end());
1094 }
1095
1096 /// Throw away any remaining cleanups at the end of evaluation. If any
1097 /// cleanups would have had a side-effect, note that as an unmodeled
1098 /// side-effect and return false. Otherwise, return true.
discardCleanups()1099 bool discardCleanups() {
1100 for (Cleanup &C : CleanupStack) {
1101 if (C.hasSideEffect() && !noteSideEffect()) {
1102 CleanupStack.clear();
1103 return false;
1104 }
1105 }
1106 CleanupStack.clear();
1107 return true;
1108 }
1109
1110 private:
getCurrentFrame()1111 interp::Frame *getCurrentFrame() override { return CurrentCall; }
getBottomFrame() const1112 const interp::Frame *getBottomFrame() const override { return &BottomFrame; }
1113
hasActiveDiagnostic()1114 bool hasActiveDiagnostic() override { return HasActiveDiagnostic; }
setActiveDiagnostic(bool Flag)1115 void setActiveDiagnostic(bool Flag) override { HasActiveDiagnostic = Flag; }
1116
setFoldFailureDiagnostic(bool Flag)1117 void setFoldFailureDiagnostic(bool Flag) override {
1118 HasFoldFailureDiagnostic = Flag;
1119 }
1120
getEvalStatus() const1121 Expr::EvalStatus &getEvalStatus() const override { return EvalStatus; }
1122
getCtx() const1123 ASTContext &getCtx() const override { return Ctx; }
1124
1125 // If we have a prior diagnostic, it will be noting that the expression
1126 // isn't a constant expression. This diagnostic is more important,
1127 // unless we require this evaluation to produce a constant expression.
1128 //
1129 // FIXME: We might want to show both diagnostics to the user in
1130 // EM_ConstantFold mode.
hasPriorDiagnostic()1131 bool hasPriorDiagnostic() override {
1132 if (!EvalStatus.Diag->empty()) {
1133 switch (EvalMode) {
1134 case EM_ConstantFold:
1135 case EM_IgnoreSideEffects:
1136 if (!HasFoldFailureDiagnostic)
1137 break;
1138 // We've already failed to fold something. Keep that diagnostic.
1139 LLVM_FALLTHROUGH;
1140 case EM_ConstantExpression:
1141 case EM_ConstantExpressionUnevaluated:
1142 setActiveDiagnostic(false);
1143 return true;
1144 }
1145 }
1146 return false;
1147 }
1148
getCallStackDepth()1149 unsigned getCallStackDepth() override { return CallStackDepth; }
1150
1151 public:
1152 /// Should we continue evaluation after encountering a side-effect that we
1153 /// couldn't model?
keepEvaluatingAfterSideEffect()1154 bool keepEvaluatingAfterSideEffect() {
1155 switch (EvalMode) {
1156 case EM_IgnoreSideEffects:
1157 return true;
1158
1159 case EM_ConstantExpression:
1160 case EM_ConstantExpressionUnevaluated:
1161 case EM_ConstantFold:
1162 // By default, assume any side effect might be valid in some other
1163 // evaluation of this expression from a different context.
1164 return checkingPotentialConstantExpression() ||
1165 checkingForUndefinedBehavior();
1166 }
1167 llvm_unreachable("Missed EvalMode case");
1168 }
1169
1170 /// Note that we have had a side-effect, and determine whether we should
1171 /// keep evaluating.
noteSideEffect()1172 bool noteSideEffect() {
1173 EvalStatus.HasSideEffects = true;
1174 return keepEvaluatingAfterSideEffect();
1175 }
1176
1177 /// Should we continue evaluation after encountering undefined behavior?
keepEvaluatingAfterUndefinedBehavior()1178 bool keepEvaluatingAfterUndefinedBehavior() {
1179 switch (EvalMode) {
1180 case EM_IgnoreSideEffects:
1181 case EM_ConstantFold:
1182 return true;
1183
1184 case EM_ConstantExpression:
1185 case EM_ConstantExpressionUnevaluated:
1186 return checkingForUndefinedBehavior();
1187 }
1188 llvm_unreachable("Missed EvalMode case");
1189 }
1190
1191 /// Note that we hit something that was technically undefined behavior, but
1192 /// that we can evaluate past it (such as signed overflow or floating-point
1193 /// division by zero.)
noteUndefinedBehavior()1194 bool noteUndefinedBehavior() override {
1195 EvalStatus.HasUndefinedBehavior = true;
1196 return keepEvaluatingAfterUndefinedBehavior();
1197 }
1198
1199 /// Should we continue evaluation as much as possible after encountering a
1200 /// construct which can't be reduced to a value?
keepEvaluatingAfterFailure() const1201 bool keepEvaluatingAfterFailure() const override {
1202 if (!StepsLeft)
1203 return false;
1204
1205 switch (EvalMode) {
1206 case EM_ConstantExpression:
1207 case EM_ConstantExpressionUnevaluated:
1208 case EM_ConstantFold:
1209 case EM_IgnoreSideEffects:
1210 return checkingPotentialConstantExpression() ||
1211 checkingForUndefinedBehavior();
1212 }
1213 llvm_unreachable("Missed EvalMode case");
1214 }
1215
1216 /// Notes that we failed to evaluate an expression that other expressions
1217 /// directly depend on, and determine if we should keep evaluating. This
1218 /// should only be called if we actually intend to keep evaluating.
1219 ///
1220 /// Call noteSideEffect() instead if we may be able to ignore the value that
1221 /// we failed to evaluate, e.g. if we failed to evaluate Foo() in:
1222 ///
1223 /// (Foo(), 1) // use noteSideEffect
1224 /// (Foo() || true) // use noteSideEffect
1225 /// Foo() + 1 // use noteFailure
noteFailure()1226 LLVM_NODISCARD bool noteFailure() {
1227 // Failure when evaluating some expression often means there is some
1228 // subexpression whose evaluation was skipped. Therefore, (because we
1229 // don't track whether we skipped an expression when unwinding after an
1230 // evaluation failure) every evaluation failure that bubbles up from a
1231 // subexpression implies that a side-effect has potentially happened. We
1232 // skip setting the HasSideEffects flag to true until we decide to
1233 // continue evaluating after that point, which happens here.
1234 bool KeepGoing = keepEvaluatingAfterFailure();
1235 EvalStatus.HasSideEffects |= KeepGoing;
1236 return KeepGoing;
1237 }
1238
1239 class ArrayInitLoopIndex {
1240 EvalInfo &Info;
1241 uint64_t OuterIndex;
1242
1243 public:
ArrayInitLoopIndex(EvalInfo & Info)1244 ArrayInitLoopIndex(EvalInfo &Info)
1245 : Info(Info), OuterIndex(Info.ArrayInitIndex) {
1246 Info.ArrayInitIndex = 0;
1247 }
~ArrayInitLoopIndex()1248 ~ArrayInitLoopIndex() { Info.ArrayInitIndex = OuterIndex; }
1249
operator uint64_t&()1250 operator uint64_t&() { return Info.ArrayInitIndex; }
1251 };
1252 };
1253
1254 /// Object used to treat all foldable expressions as constant expressions.
1255 struct FoldConstant {
1256 EvalInfo &Info;
1257 bool Enabled;
1258 bool HadNoPriorDiags;
1259 EvalInfo::EvaluationMode OldMode;
1260
FoldConstant__anon4a4db2530311::FoldConstant1261 explicit FoldConstant(EvalInfo &Info, bool Enabled)
1262 : Info(Info),
1263 Enabled(Enabled),
1264 HadNoPriorDiags(Info.EvalStatus.Diag &&
1265 Info.EvalStatus.Diag->empty() &&
1266 !Info.EvalStatus.HasSideEffects),
1267 OldMode(Info.EvalMode) {
1268 if (Enabled)
1269 Info.EvalMode = EvalInfo::EM_ConstantFold;
1270 }
keepDiagnostics__anon4a4db2530311::FoldConstant1271 void keepDiagnostics() { Enabled = false; }
~FoldConstant__anon4a4db2530311::FoldConstant1272 ~FoldConstant() {
1273 if (Enabled && HadNoPriorDiags && !Info.EvalStatus.Diag->empty() &&
1274 !Info.EvalStatus.HasSideEffects)
1275 Info.EvalStatus.Diag->clear();
1276 Info.EvalMode = OldMode;
1277 }
1278 };
1279
1280 /// RAII object used to set the current evaluation mode to ignore
1281 /// side-effects.
1282 struct IgnoreSideEffectsRAII {
1283 EvalInfo &Info;
1284 EvalInfo::EvaluationMode OldMode;
IgnoreSideEffectsRAII__anon4a4db2530311::IgnoreSideEffectsRAII1285 explicit IgnoreSideEffectsRAII(EvalInfo &Info)
1286 : Info(Info), OldMode(Info.EvalMode) {
1287 Info.EvalMode = EvalInfo::EM_IgnoreSideEffects;
1288 }
1289
~IgnoreSideEffectsRAII__anon4a4db2530311::IgnoreSideEffectsRAII1290 ~IgnoreSideEffectsRAII() { Info.EvalMode = OldMode; }
1291 };
1292
1293 /// RAII object used to optionally suppress diagnostics and side-effects from
1294 /// a speculative evaluation.
1295 class SpeculativeEvaluationRAII {
1296 EvalInfo *Info = nullptr;
1297 Expr::EvalStatus OldStatus;
1298 unsigned OldSpeculativeEvaluationDepth;
1299
moveFromAndCancel(SpeculativeEvaluationRAII && Other)1300 void moveFromAndCancel(SpeculativeEvaluationRAII &&Other) {
1301 Info = Other.Info;
1302 OldStatus = Other.OldStatus;
1303 OldSpeculativeEvaluationDepth = Other.OldSpeculativeEvaluationDepth;
1304 Other.Info = nullptr;
1305 }
1306
maybeRestoreState()1307 void maybeRestoreState() {
1308 if (!Info)
1309 return;
1310
1311 Info->EvalStatus = OldStatus;
1312 Info->SpeculativeEvaluationDepth = OldSpeculativeEvaluationDepth;
1313 }
1314
1315 public:
1316 SpeculativeEvaluationRAII() = default;
1317
SpeculativeEvaluationRAII(EvalInfo & Info,SmallVectorImpl<PartialDiagnosticAt> * NewDiag=nullptr)1318 SpeculativeEvaluationRAII(
1319 EvalInfo &Info, SmallVectorImpl<PartialDiagnosticAt> *NewDiag = nullptr)
1320 : Info(&Info), OldStatus(Info.EvalStatus),
1321 OldSpeculativeEvaluationDepth(Info.SpeculativeEvaluationDepth) {
1322 Info.EvalStatus.Diag = NewDiag;
1323 Info.SpeculativeEvaluationDepth = Info.CallStackDepth + 1;
1324 }
1325
1326 SpeculativeEvaluationRAII(const SpeculativeEvaluationRAII &Other) = delete;
SpeculativeEvaluationRAII(SpeculativeEvaluationRAII && Other)1327 SpeculativeEvaluationRAII(SpeculativeEvaluationRAII &&Other) {
1328 moveFromAndCancel(std::move(Other));
1329 }
1330
operator =(SpeculativeEvaluationRAII && Other)1331 SpeculativeEvaluationRAII &operator=(SpeculativeEvaluationRAII &&Other) {
1332 maybeRestoreState();
1333 moveFromAndCancel(std::move(Other));
1334 return *this;
1335 }
1336
~SpeculativeEvaluationRAII()1337 ~SpeculativeEvaluationRAII() { maybeRestoreState(); }
1338 };
1339
1340 /// RAII object wrapping a full-expression or block scope, and handling
1341 /// the ending of the lifetime of temporaries created within it.
1342 template<ScopeKind Kind>
1343 class ScopeRAII {
1344 EvalInfo &Info;
1345 unsigned OldStackSize;
1346 public:
ScopeRAII(EvalInfo & Info)1347 ScopeRAII(EvalInfo &Info)
1348 : Info(Info), OldStackSize(Info.CleanupStack.size()) {
1349 // Push a new temporary version. This is needed to distinguish between
1350 // temporaries created in different iterations of a loop.
1351 Info.CurrentCall->pushTempVersion();
1352 }
destroy(bool RunDestructors=true)1353 bool destroy(bool RunDestructors = true) {
1354 bool OK = cleanup(Info, RunDestructors, OldStackSize);
1355 OldStackSize = -1U;
1356 return OK;
1357 }
~ScopeRAII()1358 ~ScopeRAII() {
1359 if (OldStackSize != -1U)
1360 destroy(false);
1361 // Body moved to a static method to encourage the compiler to inline away
1362 // instances of this class.
1363 Info.CurrentCall->popTempVersion();
1364 }
1365 private:
cleanup(EvalInfo & Info,bool RunDestructors,unsigned OldStackSize)1366 static bool cleanup(EvalInfo &Info, bool RunDestructors,
1367 unsigned OldStackSize) {
1368 assert(OldStackSize <= Info.CleanupStack.size() &&
1369 "running cleanups out of order?");
1370
1371 // Run all cleanups for a block scope, and non-lifetime-extended cleanups
1372 // for a full-expression scope.
1373 bool Success = true;
1374 for (unsigned I = Info.CleanupStack.size(); I > OldStackSize; --I) {
1375 if (Info.CleanupStack[I - 1].isDestroyedAtEndOf(Kind)) {
1376 if (!Info.CleanupStack[I - 1].endLifetime(Info, RunDestructors)) {
1377 Success = false;
1378 break;
1379 }
1380 }
1381 }
1382
1383 // Compact any retained cleanups.
1384 auto NewEnd = Info.CleanupStack.begin() + OldStackSize;
1385 if (Kind != ScopeKind::Block)
1386 NewEnd =
1387 std::remove_if(NewEnd, Info.CleanupStack.end(), [](Cleanup &C) {
1388 return C.isDestroyedAtEndOf(Kind);
1389 });
1390 Info.CleanupStack.erase(NewEnd, Info.CleanupStack.end());
1391 return Success;
1392 }
1393 };
1394 typedef ScopeRAII<ScopeKind::Block> BlockScopeRAII;
1395 typedef ScopeRAII<ScopeKind::FullExpression> FullExpressionRAII;
1396 typedef ScopeRAII<ScopeKind::Call> CallScopeRAII;
1397 }
1398
checkSubobject(EvalInfo & Info,const Expr * E,CheckSubobjectKind CSK)1399 bool SubobjectDesignator::checkSubobject(EvalInfo &Info, const Expr *E,
1400 CheckSubobjectKind CSK) {
1401 if (Invalid)
1402 return false;
1403 if (isOnePastTheEnd()) {
1404 Info.CCEDiag(E, diag::note_constexpr_past_end_subobject)
1405 << CSK;
1406 setInvalid();
1407 return false;
1408 }
1409 // Note, we do not diagnose if isMostDerivedAnUnsizedArray(), because there
1410 // must actually be at least one array element; even a VLA cannot have a
1411 // bound of zero. And if our index is nonzero, we already had a CCEDiag.
1412 return true;
1413 }
1414
diagnoseUnsizedArrayPointerArithmetic(EvalInfo & Info,const Expr * E)1415 void SubobjectDesignator::diagnoseUnsizedArrayPointerArithmetic(EvalInfo &Info,
1416 const Expr *E) {
1417 Info.CCEDiag(E, diag::note_constexpr_unsized_array_indexed);
1418 // Do not set the designator as invalid: we can represent this situation,
1419 // and correct handling of __builtin_object_size requires us to do so.
1420 }
1421
diagnosePointerArithmetic(EvalInfo & Info,const Expr * E,const APSInt & N)1422 void SubobjectDesignator::diagnosePointerArithmetic(EvalInfo &Info,
1423 const Expr *E,
1424 const APSInt &N) {
1425 // If we're complaining, we must be able to statically determine the size of
1426 // the most derived array.
1427 if (MostDerivedPathLength == Entries.size() && MostDerivedIsArrayElement)
1428 Info.CCEDiag(E, diag::note_constexpr_array_index)
1429 << N << /*array*/ 0
1430 << static_cast<unsigned>(getMostDerivedArraySize());
1431 else
1432 Info.CCEDiag(E, diag::note_constexpr_array_index)
1433 << N << /*non-array*/ 1;
1434 setInvalid();
1435 }
1436
CallStackFrame(EvalInfo & Info,SourceLocation CallLoc,const FunctionDecl * Callee,const LValue * This,CallRef Call)1437 CallStackFrame::CallStackFrame(EvalInfo &Info, SourceLocation CallLoc,
1438 const FunctionDecl *Callee, const LValue *This,
1439 CallRef Call)
1440 : Info(Info), Caller(Info.CurrentCall), Callee(Callee), This(This),
1441 Arguments(Call), CallLoc(CallLoc), Index(Info.NextCallIndex++) {
1442 Info.CurrentCall = this;
1443 ++Info.CallStackDepth;
1444 }
1445
~CallStackFrame()1446 CallStackFrame::~CallStackFrame() {
1447 assert(Info.CurrentCall == this && "calls retired out of order");
1448 --Info.CallStackDepth;
1449 Info.CurrentCall = Caller;
1450 }
1451
isRead(AccessKinds AK)1452 static bool isRead(AccessKinds AK) {
1453 return AK == AK_Read || AK == AK_ReadObjectRepresentation;
1454 }
1455
isModification(AccessKinds AK)1456 static bool isModification(AccessKinds AK) {
1457 switch (AK) {
1458 case AK_Read:
1459 case AK_ReadObjectRepresentation:
1460 case AK_MemberCall:
1461 case AK_DynamicCast:
1462 case AK_TypeId:
1463 return false;
1464 case AK_Assign:
1465 case AK_Increment:
1466 case AK_Decrement:
1467 case AK_Construct:
1468 case AK_Destroy:
1469 return true;
1470 }
1471 llvm_unreachable("unknown access kind");
1472 }
1473
isAnyAccess(AccessKinds AK)1474 static bool isAnyAccess(AccessKinds AK) {
1475 return isRead(AK) || isModification(AK);
1476 }
1477
1478 /// Is this an access per the C++ definition?
isFormalAccess(AccessKinds AK)1479 static bool isFormalAccess(AccessKinds AK) {
1480 return isAnyAccess(AK) && AK != AK_Construct && AK != AK_Destroy;
1481 }
1482
1483 /// Is this kind of axcess valid on an indeterminate object value?
isValidIndeterminateAccess(AccessKinds AK)1484 static bool isValidIndeterminateAccess(AccessKinds AK) {
1485 switch (AK) {
1486 case AK_Read:
1487 case AK_Increment:
1488 case AK_Decrement:
1489 // These need the object's value.
1490 return false;
1491
1492 case AK_ReadObjectRepresentation:
1493 case AK_Assign:
1494 case AK_Construct:
1495 case AK_Destroy:
1496 // Construction and destruction don't need the value.
1497 return true;
1498
1499 case AK_MemberCall:
1500 case AK_DynamicCast:
1501 case AK_TypeId:
1502 // These aren't really meaningful on scalars.
1503 return true;
1504 }
1505 llvm_unreachable("unknown access kind");
1506 }
1507
1508 namespace {
1509 struct ComplexValue {
1510 private:
1511 bool IsInt;
1512
1513 public:
1514 APSInt IntReal, IntImag;
1515 APFloat FloatReal, FloatImag;
1516
ComplexValue__anon4a4db2530611::ComplexValue1517 ComplexValue() : FloatReal(APFloat::Bogus()), FloatImag(APFloat::Bogus()) {}
1518
makeComplexFloat__anon4a4db2530611::ComplexValue1519 void makeComplexFloat() { IsInt = false; }
isComplexFloat__anon4a4db2530611::ComplexValue1520 bool isComplexFloat() const { return !IsInt; }
getComplexFloatReal__anon4a4db2530611::ComplexValue1521 APFloat &getComplexFloatReal() { return FloatReal; }
getComplexFloatImag__anon4a4db2530611::ComplexValue1522 APFloat &getComplexFloatImag() { return FloatImag; }
1523
makeComplexInt__anon4a4db2530611::ComplexValue1524 void makeComplexInt() { IsInt = true; }
isComplexInt__anon4a4db2530611::ComplexValue1525 bool isComplexInt() const { return IsInt; }
getComplexIntReal__anon4a4db2530611::ComplexValue1526 APSInt &getComplexIntReal() { return IntReal; }
getComplexIntImag__anon4a4db2530611::ComplexValue1527 APSInt &getComplexIntImag() { return IntImag; }
1528
moveInto__anon4a4db2530611::ComplexValue1529 void moveInto(APValue &v) const {
1530 if (isComplexFloat())
1531 v = APValue(FloatReal, FloatImag);
1532 else
1533 v = APValue(IntReal, IntImag);
1534 }
setFrom__anon4a4db2530611::ComplexValue1535 void setFrom(const APValue &v) {
1536 assert(v.isComplexFloat() || v.isComplexInt());
1537 if (v.isComplexFloat()) {
1538 makeComplexFloat();
1539 FloatReal = v.getComplexFloatReal();
1540 FloatImag = v.getComplexFloatImag();
1541 } else {
1542 makeComplexInt();
1543 IntReal = v.getComplexIntReal();
1544 IntImag = v.getComplexIntImag();
1545 }
1546 }
1547 };
1548
1549 struct LValue {
1550 APValue::LValueBase Base;
1551 CharUnits Offset;
1552 SubobjectDesignator Designator;
1553 bool IsNullPtr : 1;
1554 bool InvalidBase : 1;
1555
getLValueBase__anon4a4db2530611::LValue1556 const APValue::LValueBase getLValueBase() const { return Base; }
getLValueOffset__anon4a4db2530611::LValue1557 CharUnits &getLValueOffset() { return Offset; }
getLValueOffset__anon4a4db2530611::LValue1558 const CharUnits &getLValueOffset() const { return Offset; }
getLValueDesignator__anon4a4db2530611::LValue1559 SubobjectDesignator &getLValueDesignator() { return Designator; }
getLValueDesignator__anon4a4db2530611::LValue1560 const SubobjectDesignator &getLValueDesignator() const { return Designator;}
isNullPointer__anon4a4db2530611::LValue1561 bool isNullPointer() const { return IsNullPtr;}
1562
getLValueCallIndex__anon4a4db2530611::LValue1563 unsigned getLValueCallIndex() const { return Base.getCallIndex(); }
getLValueVersion__anon4a4db2530611::LValue1564 unsigned getLValueVersion() const { return Base.getVersion(); }
1565
moveInto__anon4a4db2530611::LValue1566 void moveInto(APValue &V) const {
1567 if (Designator.Invalid)
1568 V = APValue(Base, Offset, APValue::NoLValuePath(), IsNullPtr);
1569 else {
1570 assert(!InvalidBase && "APValues can't handle invalid LValue bases");
1571 V = APValue(Base, Offset, Designator.Entries,
1572 Designator.IsOnePastTheEnd, IsNullPtr);
1573 }
1574 }
setFrom__anon4a4db2530611::LValue1575 void setFrom(ASTContext &Ctx, const APValue &V) {
1576 assert(V.isLValue() && "Setting LValue from a non-LValue?");
1577 Base = V.getLValueBase();
1578 Offset = V.getLValueOffset();
1579 InvalidBase = false;
1580 Designator = SubobjectDesignator(Ctx, V);
1581 IsNullPtr = V.isNullPointer();
1582 }
1583
set__anon4a4db2530611::LValue1584 void set(APValue::LValueBase B, bool BInvalid = false) {
1585 #ifndef NDEBUG
1586 // We only allow a few types of invalid bases. Enforce that here.
1587 if (BInvalid) {
1588 const auto *E = B.get<const Expr *>();
1589 assert((isa<MemberExpr>(E) || tryUnwrapAllocSizeCall(E)) &&
1590 "Unexpected type of invalid base");
1591 }
1592 #endif
1593
1594 Base = B;
1595 Offset = CharUnits::fromQuantity(0);
1596 InvalidBase = BInvalid;
1597 Designator = SubobjectDesignator(getType(B));
1598 IsNullPtr = false;
1599 }
1600
setNull__anon4a4db2530611::LValue1601 void setNull(ASTContext &Ctx, QualType PointerTy) {
1602 Base = (const ValueDecl *)nullptr;
1603 Offset =
1604 CharUnits::fromQuantity(Ctx.getTargetNullPointerValue(PointerTy));
1605 InvalidBase = false;
1606 Designator = SubobjectDesignator(PointerTy->getPointeeType());
1607 IsNullPtr = true;
1608 }
1609
setInvalid__anon4a4db2530611::LValue1610 void setInvalid(APValue::LValueBase B, unsigned I = 0) {
1611 set(B, true);
1612 }
1613
toString__anon4a4db2530611::LValue1614 std::string toString(ASTContext &Ctx, QualType T) const {
1615 APValue Printable;
1616 moveInto(Printable);
1617 return Printable.getAsString(Ctx, T);
1618 }
1619
1620 private:
1621 // Check that this LValue is not based on a null pointer. If it is, produce
1622 // a diagnostic and mark the designator as invalid.
1623 template <typename GenDiagType>
checkNullPointerDiagnosingWith__anon4a4db2530611::LValue1624 bool checkNullPointerDiagnosingWith(const GenDiagType &GenDiag) {
1625 if (Designator.Invalid)
1626 return false;
1627 if (IsNullPtr) {
1628 GenDiag();
1629 Designator.setInvalid();
1630 return false;
1631 }
1632 return true;
1633 }
1634
1635 public:
checkNullPointer__anon4a4db2530611::LValue1636 bool checkNullPointer(EvalInfo &Info, const Expr *E,
1637 CheckSubobjectKind CSK) {
1638 return checkNullPointerDiagnosingWith([&Info, E, CSK] {
1639 Info.CCEDiag(E, diag::note_constexpr_null_subobject) << CSK;
1640 });
1641 }
1642
checkNullPointerForFoldAccess__anon4a4db2530611::LValue1643 bool checkNullPointerForFoldAccess(EvalInfo &Info, const Expr *E,
1644 AccessKinds AK) {
1645 return checkNullPointerDiagnosingWith([&Info, E, AK] {
1646 Info.FFDiag(E, diag::note_constexpr_access_null) << AK;
1647 });
1648 }
1649
1650 // Check this LValue refers to an object. If not, set the designator to be
1651 // invalid and emit a diagnostic.
checkSubobject__anon4a4db2530611::LValue1652 bool checkSubobject(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK) {
1653 return (CSK == CSK_ArrayToPointer || checkNullPointer(Info, E, CSK)) &&
1654 Designator.checkSubobject(Info, E, CSK);
1655 }
1656
addDecl__anon4a4db2530611::LValue1657 void addDecl(EvalInfo &Info, const Expr *E,
1658 const Decl *D, bool Virtual = false) {
1659 if (checkSubobject(Info, E, isa<FieldDecl>(D) ? CSK_Field : CSK_Base))
1660 Designator.addDeclUnchecked(D, Virtual);
1661 }
addUnsizedArray__anon4a4db2530611::LValue1662 void addUnsizedArray(EvalInfo &Info, const Expr *E, QualType ElemTy) {
1663 if (!Designator.Entries.empty()) {
1664 Info.CCEDiag(E, diag::note_constexpr_unsupported_unsized_array);
1665 Designator.setInvalid();
1666 return;
1667 }
1668 if (checkSubobject(Info, E, CSK_ArrayToPointer)) {
1669 assert(getType(Base)->isPointerType() || getType(Base)->isArrayType());
1670 Designator.FirstEntryIsAnUnsizedArray = true;
1671 Designator.addUnsizedArrayUnchecked(ElemTy);
1672 }
1673 }
addArray__anon4a4db2530611::LValue1674 void addArray(EvalInfo &Info, const Expr *E, const ConstantArrayType *CAT) {
1675 if (checkSubobject(Info, E, CSK_ArrayToPointer))
1676 Designator.addArrayUnchecked(CAT);
1677 }
addComplex__anon4a4db2530611::LValue1678 void addComplex(EvalInfo &Info, const Expr *E, QualType EltTy, bool Imag) {
1679 if (checkSubobject(Info, E, Imag ? CSK_Imag : CSK_Real))
1680 Designator.addComplexUnchecked(EltTy, Imag);
1681 }
clearIsNullPointer__anon4a4db2530611::LValue1682 void clearIsNullPointer() {
1683 IsNullPtr = false;
1684 }
adjustOffsetAndIndex__anon4a4db2530611::LValue1685 void adjustOffsetAndIndex(EvalInfo &Info, const Expr *E,
1686 const APSInt &Index, CharUnits ElementSize) {
1687 // An index of 0 has no effect. (In C, adding 0 to a null pointer is UB,
1688 // but we're not required to diagnose it and it's valid in C++.)
1689 if (!Index)
1690 return;
1691
1692 // Compute the new offset in the appropriate width, wrapping at 64 bits.
1693 // FIXME: When compiling for a 32-bit target, we should use 32-bit
1694 // offsets.
1695 uint64_t Offset64 = Offset.getQuantity();
1696 uint64_t ElemSize64 = ElementSize.getQuantity();
1697 uint64_t Index64 = Index.extOrTrunc(64).getZExtValue();
1698 Offset = CharUnits::fromQuantity(Offset64 + ElemSize64 * Index64);
1699
1700 if (checkNullPointer(Info, E, CSK_ArrayIndex))
1701 Designator.adjustIndex(Info, E, Index);
1702 clearIsNullPointer();
1703 }
adjustOffset__anon4a4db2530611::LValue1704 void adjustOffset(CharUnits N) {
1705 Offset += N;
1706 if (N.getQuantity())
1707 clearIsNullPointer();
1708 }
1709 };
1710
1711 struct MemberPtr {
MemberPtr__anon4a4db2530611::MemberPtr1712 MemberPtr() {}
MemberPtr__anon4a4db2530611::MemberPtr1713 explicit MemberPtr(const ValueDecl *Decl) :
1714 DeclAndIsDerivedMember(Decl, false), Path() {}
1715
1716 /// The member or (direct or indirect) field referred to by this member
1717 /// pointer, or 0 if this is a null member pointer.
getDecl__anon4a4db2530611::MemberPtr1718 const ValueDecl *getDecl() const {
1719 return DeclAndIsDerivedMember.getPointer();
1720 }
1721 /// Is this actually a member of some type derived from the relevant class?
isDerivedMember__anon4a4db2530611::MemberPtr1722 bool isDerivedMember() const {
1723 return DeclAndIsDerivedMember.getInt();
1724 }
1725 /// Get the class which the declaration actually lives in.
getContainingRecord__anon4a4db2530611::MemberPtr1726 const CXXRecordDecl *getContainingRecord() const {
1727 return cast<CXXRecordDecl>(
1728 DeclAndIsDerivedMember.getPointer()->getDeclContext());
1729 }
1730
moveInto__anon4a4db2530611::MemberPtr1731 void moveInto(APValue &V) const {
1732 V = APValue(getDecl(), isDerivedMember(), Path);
1733 }
setFrom__anon4a4db2530611::MemberPtr1734 void setFrom(const APValue &V) {
1735 assert(V.isMemberPointer());
1736 DeclAndIsDerivedMember.setPointer(V.getMemberPointerDecl());
1737 DeclAndIsDerivedMember.setInt(V.isMemberPointerToDerivedMember());
1738 Path.clear();
1739 ArrayRef<const CXXRecordDecl*> P = V.getMemberPointerPath();
1740 Path.insert(Path.end(), P.begin(), P.end());
1741 }
1742
1743 /// DeclAndIsDerivedMember - The member declaration, and a flag indicating
1744 /// whether the member is a member of some class derived from the class type
1745 /// of the member pointer.
1746 llvm::PointerIntPair<const ValueDecl*, 1, bool> DeclAndIsDerivedMember;
1747 /// Path - The path of base/derived classes from the member declaration's
1748 /// class (exclusive) to the class type of the member pointer (inclusive).
1749 SmallVector<const CXXRecordDecl*, 4> Path;
1750
1751 /// Perform a cast towards the class of the Decl (either up or down the
1752 /// hierarchy).
castBack__anon4a4db2530611::MemberPtr1753 bool castBack(const CXXRecordDecl *Class) {
1754 assert(!Path.empty());
1755 const CXXRecordDecl *Expected;
1756 if (Path.size() >= 2)
1757 Expected = Path[Path.size() - 2];
1758 else
1759 Expected = getContainingRecord();
1760 if (Expected->getCanonicalDecl() != Class->getCanonicalDecl()) {
1761 // C++11 [expr.static.cast]p12: In a conversion from (D::*) to (B::*),
1762 // if B does not contain the original member and is not a base or
1763 // derived class of the class containing the original member, the result
1764 // of the cast is undefined.
1765 // C++11 [conv.mem]p2 does not cover this case for a cast from (B::*) to
1766 // (D::*). We consider that to be a language defect.
1767 return false;
1768 }
1769 Path.pop_back();
1770 return true;
1771 }
1772 /// Perform a base-to-derived member pointer cast.
castToDerived__anon4a4db2530611::MemberPtr1773 bool castToDerived(const CXXRecordDecl *Derived) {
1774 if (!getDecl())
1775 return true;
1776 if (!isDerivedMember()) {
1777 Path.push_back(Derived);
1778 return true;
1779 }
1780 if (!castBack(Derived))
1781 return false;
1782 if (Path.empty())
1783 DeclAndIsDerivedMember.setInt(false);
1784 return true;
1785 }
1786 /// Perform a derived-to-base member pointer cast.
castToBase__anon4a4db2530611::MemberPtr1787 bool castToBase(const CXXRecordDecl *Base) {
1788 if (!getDecl())
1789 return true;
1790 if (Path.empty())
1791 DeclAndIsDerivedMember.setInt(true);
1792 if (isDerivedMember()) {
1793 Path.push_back(Base);
1794 return true;
1795 }
1796 return castBack(Base);
1797 }
1798 };
1799
1800 /// Compare two member pointers, which are assumed to be of the same type.
operator ==(const MemberPtr & LHS,const MemberPtr & RHS)1801 static bool operator==(const MemberPtr &LHS, const MemberPtr &RHS) {
1802 if (!LHS.getDecl() || !RHS.getDecl())
1803 return !LHS.getDecl() && !RHS.getDecl();
1804 if (LHS.getDecl()->getCanonicalDecl() != RHS.getDecl()->getCanonicalDecl())
1805 return false;
1806 return LHS.Path == RHS.Path;
1807 }
1808 }
1809
1810 static bool Evaluate(APValue &Result, EvalInfo &Info, const Expr *E);
1811 static bool EvaluateInPlace(APValue &Result, EvalInfo &Info,
1812 const LValue &This, const Expr *E,
1813 bool AllowNonLiteralTypes = false);
1814 static bool EvaluateLValue(const Expr *E, LValue &Result, EvalInfo &Info,
1815 bool InvalidBaseOK = false);
1816 static bool EvaluatePointer(const Expr *E, LValue &Result, EvalInfo &Info,
1817 bool InvalidBaseOK = false);
1818 static bool EvaluateMemberPointer(const Expr *E, MemberPtr &Result,
1819 EvalInfo &Info);
1820 static bool EvaluateTemporary(const Expr *E, LValue &Result, EvalInfo &Info);
1821 static bool EvaluateInteger(const Expr *E, APSInt &Result, EvalInfo &Info);
1822 static bool EvaluateIntegerOrLValue(const Expr *E, APValue &Result,
1823 EvalInfo &Info);
1824 static bool EvaluateFloat(const Expr *E, APFloat &Result, EvalInfo &Info);
1825 static bool EvaluateComplex(const Expr *E, ComplexValue &Res, EvalInfo &Info);
1826 static bool EvaluateAtomic(const Expr *E, const LValue *This, APValue &Result,
1827 EvalInfo &Info);
1828 static bool EvaluateAsRValue(EvalInfo &Info, const Expr *E, APValue &Result);
1829 static bool EvaluateBuiltinStrLen(const Expr *E, uint64_t &Result,
1830 EvalInfo &Info);
1831
1832 /// Evaluate an integer or fixed point expression into an APResult.
1833 static bool EvaluateFixedPointOrInteger(const Expr *E, APFixedPoint &Result,
1834 EvalInfo &Info);
1835
1836 /// Evaluate only a fixed point expression into an APResult.
1837 static bool EvaluateFixedPoint(const Expr *E, APFixedPoint &Result,
1838 EvalInfo &Info);
1839
1840 //===----------------------------------------------------------------------===//
1841 // Misc utilities
1842 //===----------------------------------------------------------------------===//
1843
1844 /// Negate an APSInt in place, converting it to a signed form if necessary, and
1845 /// preserving its value (by extending by up to one bit as needed).
negateAsSigned(APSInt & Int)1846 static void negateAsSigned(APSInt &Int) {
1847 if (Int.isUnsigned() || Int.isMinSignedValue()) {
1848 Int = Int.extend(Int.getBitWidth() + 1);
1849 Int.setIsSigned(true);
1850 }
1851 Int = -Int;
1852 }
1853
1854 template<typename KeyT>
createTemporary(const KeyT * Key,QualType T,ScopeKind Scope,LValue & LV)1855 APValue &CallStackFrame::createTemporary(const KeyT *Key, QualType T,
1856 ScopeKind Scope, LValue &LV) {
1857 unsigned Version = getTempVersion();
1858 APValue::LValueBase Base(Key, Index, Version);
1859 LV.set(Base);
1860 return createLocal(Base, Key, T, Scope);
1861 }
1862
1863 /// Allocate storage for a parameter of a function call made in this frame.
createParam(CallRef Args,const ParmVarDecl * PVD,LValue & LV)1864 APValue &CallStackFrame::createParam(CallRef Args, const ParmVarDecl *PVD,
1865 LValue &LV) {
1866 assert(Args.CallIndex == Index && "creating parameter in wrong frame");
1867 APValue::LValueBase Base(PVD, Index, Args.Version);
1868 LV.set(Base);
1869 // We always destroy parameters at the end of the call, even if we'd allow
1870 // them to live to the end of the full-expression at runtime, in order to
1871 // give portable results and match other compilers.
1872 return createLocal(Base, PVD, PVD->getType(), ScopeKind::Call);
1873 }
1874
createLocal(APValue::LValueBase Base,const void * Key,QualType T,ScopeKind Scope)1875 APValue &CallStackFrame::createLocal(APValue::LValueBase Base, const void *Key,
1876 QualType T, ScopeKind Scope) {
1877 assert(Base.getCallIndex() == Index && "lvalue for wrong frame");
1878 unsigned Version = Base.getVersion();
1879 APValue &Result = Temporaries[MapKeyTy(Key, Version)];
1880 assert(Result.isAbsent() && "local created multiple times");
1881
1882 // If we're creating a local immediately in the operand of a speculative
1883 // evaluation, don't register a cleanup to be run outside the speculative
1884 // evaluation context, since we won't actually be able to initialize this
1885 // object.
1886 if (Index <= Info.SpeculativeEvaluationDepth) {
1887 if (T.isDestructedType())
1888 Info.noteSideEffect();
1889 } else {
1890 Info.CleanupStack.push_back(Cleanup(&Result, Base, T, Scope));
1891 }
1892 return Result;
1893 }
1894
createHeapAlloc(const Expr * E,QualType T,LValue & LV)1895 APValue *EvalInfo::createHeapAlloc(const Expr *E, QualType T, LValue &LV) {
1896 if (NumHeapAllocs > DynamicAllocLValue::getMaxIndex()) {
1897 FFDiag(E, diag::note_constexpr_heap_alloc_limit_exceeded);
1898 return nullptr;
1899 }
1900
1901 DynamicAllocLValue DA(NumHeapAllocs++);
1902 LV.set(APValue::LValueBase::getDynamicAlloc(DA, T));
1903 auto Result = HeapAllocs.emplace(std::piecewise_construct,
1904 std::forward_as_tuple(DA), std::tuple<>());
1905 assert(Result.second && "reused a heap alloc index?");
1906 Result.first->second.AllocExpr = E;
1907 return &Result.first->second.Value;
1908 }
1909
1910 /// Produce a string describing the given constexpr call.
describe(raw_ostream & Out)1911 void CallStackFrame::describe(raw_ostream &Out) {
1912 unsigned ArgIndex = 0;
1913 bool IsMemberCall = isa<CXXMethodDecl>(Callee) &&
1914 !isa<CXXConstructorDecl>(Callee) &&
1915 cast<CXXMethodDecl>(Callee)->isInstance();
1916
1917 if (!IsMemberCall)
1918 Out << *Callee << '(';
1919
1920 if (This && IsMemberCall) {
1921 APValue Val;
1922 This->moveInto(Val);
1923 Val.printPretty(Out, Info.Ctx,
1924 This->Designator.MostDerivedType);
1925 // FIXME: Add parens around Val if needed.
1926 Out << "->" << *Callee << '(';
1927 IsMemberCall = false;
1928 }
1929
1930 for (FunctionDecl::param_const_iterator I = Callee->param_begin(),
1931 E = Callee->param_end(); I != E; ++I, ++ArgIndex) {
1932 if (ArgIndex > (unsigned)IsMemberCall)
1933 Out << ", ";
1934
1935 const ParmVarDecl *Param = *I;
1936 APValue *V = Info.getParamSlot(Arguments, Param);
1937 if (V)
1938 V->printPretty(Out, Info.Ctx, Param->getType());
1939 else
1940 Out << "<...>";
1941
1942 if (ArgIndex == 0 && IsMemberCall)
1943 Out << "->" << *Callee << '(';
1944 }
1945
1946 Out << ')';
1947 }
1948
1949 /// Evaluate an expression to see if it had side-effects, and discard its
1950 /// result.
1951 /// \return \c true if the caller should keep evaluating.
EvaluateIgnoredValue(EvalInfo & Info,const Expr * E)1952 static bool EvaluateIgnoredValue(EvalInfo &Info, const Expr *E) {
1953 assert(!E->isValueDependent());
1954 APValue Scratch;
1955 if (!Evaluate(Scratch, Info, E))
1956 // We don't need the value, but we might have skipped a side effect here.
1957 return Info.noteSideEffect();
1958 return true;
1959 }
1960
1961 /// Should this call expression be treated as a string literal?
IsStringLiteralCall(const CallExpr * E)1962 static bool IsStringLiteralCall(const CallExpr *E) {
1963 unsigned Builtin = E->getBuiltinCallee();
1964 return (Builtin == Builtin::BI__builtin___CFStringMakeConstantString ||
1965 Builtin == Builtin::BI__builtin___NSStringMakeConstantString);
1966 }
1967
IsGlobalLValue(APValue::LValueBase B)1968 static bool IsGlobalLValue(APValue::LValueBase B) {
1969 // C++11 [expr.const]p3 An address constant expression is a prvalue core
1970 // constant expression of pointer type that evaluates to...
1971
1972 // ... a null pointer value, or a prvalue core constant expression of type
1973 // std::nullptr_t.
1974 if (!B) return true;
1975
1976 if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) {
1977 // ... the address of an object with static storage duration,
1978 if (const VarDecl *VD = dyn_cast<VarDecl>(D))
1979 return VD->hasGlobalStorage();
1980 if (isa<TemplateParamObjectDecl>(D))
1981 return true;
1982 // ... the address of a function,
1983 // ... the address of a GUID [MS extension],
1984 return isa<FunctionDecl>(D) || isa<MSGuidDecl>(D);
1985 }
1986
1987 if (B.is<TypeInfoLValue>() || B.is<DynamicAllocLValue>())
1988 return true;
1989
1990 const Expr *E = B.get<const Expr*>();
1991 switch (E->getStmtClass()) {
1992 default:
1993 return false;
1994 case Expr::CompoundLiteralExprClass: {
1995 const CompoundLiteralExpr *CLE = cast<CompoundLiteralExpr>(E);
1996 return CLE->isFileScope() && CLE->isLValue();
1997 }
1998 case Expr::MaterializeTemporaryExprClass:
1999 // A materialized temporary might have been lifetime-extended to static
2000 // storage duration.
2001 return cast<MaterializeTemporaryExpr>(E)->getStorageDuration() == SD_Static;
2002 // A string literal has static storage duration.
2003 case Expr::StringLiteralClass:
2004 case Expr::PredefinedExprClass:
2005 case Expr::ObjCStringLiteralClass:
2006 case Expr::ObjCEncodeExprClass:
2007 return true;
2008 case Expr::ObjCBoxedExprClass:
2009 return cast<ObjCBoxedExpr>(E)->isExpressibleAsConstantInitializer();
2010 case Expr::CallExprClass:
2011 return IsStringLiteralCall(cast<CallExpr>(E));
2012 // For GCC compatibility, &&label has static storage duration.
2013 case Expr::AddrLabelExprClass:
2014 return true;
2015 // A Block literal expression may be used as the initialization value for
2016 // Block variables at global or local static scope.
2017 case Expr::BlockExprClass:
2018 return !cast<BlockExpr>(E)->getBlockDecl()->hasCaptures();
2019 case Expr::ImplicitValueInitExprClass:
2020 // FIXME:
2021 // We can never form an lvalue with an implicit value initialization as its
2022 // base through expression evaluation, so these only appear in one case: the
2023 // implicit variable declaration we invent when checking whether a constexpr
2024 // constructor can produce a constant expression. We must assume that such
2025 // an expression might be a global lvalue.
2026 return true;
2027 }
2028 }
2029
GetLValueBaseDecl(const LValue & LVal)2030 static const ValueDecl *GetLValueBaseDecl(const LValue &LVal) {
2031 return LVal.Base.dyn_cast<const ValueDecl*>();
2032 }
2033
IsLiteralLValue(const LValue & Value)2034 static bool IsLiteralLValue(const LValue &Value) {
2035 if (Value.getLValueCallIndex())
2036 return false;
2037 const Expr *E = Value.Base.dyn_cast<const Expr*>();
2038 return E && !isa<MaterializeTemporaryExpr>(E);
2039 }
2040
IsWeakLValue(const LValue & Value)2041 static bool IsWeakLValue(const LValue &Value) {
2042 const ValueDecl *Decl = GetLValueBaseDecl(Value);
2043 return Decl && Decl->isWeak();
2044 }
2045
isZeroSized(const LValue & Value)2046 static bool isZeroSized(const LValue &Value) {
2047 const ValueDecl *Decl = GetLValueBaseDecl(Value);
2048 if (Decl && isa<VarDecl>(Decl)) {
2049 QualType Ty = Decl->getType();
2050 if (Ty->isArrayType())
2051 return Ty->isIncompleteType() ||
2052 Decl->getASTContext().getTypeSize(Ty) == 0;
2053 }
2054 return false;
2055 }
2056
HasSameBase(const LValue & A,const LValue & B)2057 static bool HasSameBase(const LValue &A, const LValue &B) {
2058 if (!A.getLValueBase())
2059 return !B.getLValueBase();
2060 if (!B.getLValueBase())
2061 return false;
2062
2063 if (A.getLValueBase().getOpaqueValue() !=
2064 B.getLValueBase().getOpaqueValue())
2065 return false;
2066
2067 return A.getLValueCallIndex() == B.getLValueCallIndex() &&
2068 A.getLValueVersion() == B.getLValueVersion();
2069 }
2070
NoteLValueLocation(EvalInfo & Info,APValue::LValueBase Base)2071 static void NoteLValueLocation(EvalInfo &Info, APValue::LValueBase Base) {
2072 assert(Base && "no location for a null lvalue");
2073 const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>();
2074
2075 // For a parameter, find the corresponding call stack frame (if it still
2076 // exists), and point at the parameter of the function definition we actually
2077 // invoked.
2078 if (auto *PVD = dyn_cast_or_null<ParmVarDecl>(VD)) {
2079 unsigned Idx = PVD->getFunctionScopeIndex();
2080 for (CallStackFrame *F = Info.CurrentCall; F; F = F->Caller) {
2081 if (F->Arguments.CallIndex == Base.getCallIndex() &&
2082 F->Arguments.Version == Base.getVersion() && F->Callee &&
2083 Idx < F->Callee->getNumParams()) {
2084 VD = F->Callee->getParamDecl(Idx);
2085 break;
2086 }
2087 }
2088 }
2089
2090 if (VD)
2091 Info.Note(VD->getLocation(), diag::note_declared_at);
2092 else if (const Expr *E = Base.dyn_cast<const Expr*>())
2093 Info.Note(E->getExprLoc(), diag::note_constexpr_temporary_here);
2094 else if (DynamicAllocLValue DA = Base.dyn_cast<DynamicAllocLValue>()) {
2095 // FIXME: Produce a note for dangling pointers too.
2096 if (Optional<DynAlloc*> Alloc = Info.lookupDynamicAlloc(DA))
2097 Info.Note((*Alloc)->AllocExpr->getExprLoc(),
2098 diag::note_constexpr_dynamic_alloc_here);
2099 }
2100 // We have no information to show for a typeid(T) object.
2101 }
2102
2103 enum class CheckEvaluationResultKind {
2104 ConstantExpression,
2105 FullyInitialized,
2106 };
2107
2108 /// Materialized temporaries that we've already checked to determine if they're
2109 /// initializsed by a constant expression.
2110 using CheckedTemporaries =
2111 llvm::SmallPtrSet<const MaterializeTemporaryExpr *, 8>;
2112
2113 static bool CheckEvaluationResult(CheckEvaluationResultKind CERK,
2114 EvalInfo &Info, SourceLocation DiagLoc,
2115 QualType Type, const APValue &Value,
2116 ConstantExprKind Kind,
2117 SourceLocation SubobjectLoc,
2118 CheckedTemporaries &CheckedTemps);
2119
2120 /// Check that this reference or pointer core constant expression is a valid
2121 /// value for an address or reference constant expression. Return true if we
2122 /// 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)2123 static bool CheckLValueConstantExpression(EvalInfo &Info, SourceLocation Loc,
2124 QualType Type, const LValue &LVal,
2125 ConstantExprKind Kind,
2126 CheckedTemporaries &CheckedTemps) {
2127 bool IsReferenceType = Type->isReferenceType();
2128
2129 APValue::LValueBase Base = LVal.getLValueBase();
2130 const SubobjectDesignator &Designator = LVal.getLValueDesignator();
2131
2132 const Expr *BaseE = Base.dyn_cast<const Expr *>();
2133 const ValueDecl *BaseVD = Base.dyn_cast<const ValueDecl*>();
2134
2135 // Additional restrictions apply in a template argument. We only enforce the
2136 // C++20 restrictions here; additional syntactic and semantic restrictions
2137 // are applied elsewhere.
2138 if (isTemplateArgument(Kind)) {
2139 int InvalidBaseKind = -1;
2140 StringRef Ident;
2141 if (Base.is<TypeInfoLValue>())
2142 InvalidBaseKind = 0;
2143 else if (isa_and_nonnull<StringLiteral>(BaseE))
2144 InvalidBaseKind = 1;
2145 else if (isa_and_nonnull<MaterializeTemporaryExpr>(BaseE) ||
2146 isa_and_nonnull<LifetimeExtendedTemporaryDecl>(BaseVD))
2147 InvalidBaseKind = 2;
2148 else if (auto *PE = dyn_cast_or_null<PredefinedExpr>(BaseE)) {
2149 InvalidBaseKind = 3;
2150 Ident = PE->getIdentKindName();
2151 }
2152
2153 if (InvalidBaseKind != -1) {
2154 Info.FFDiag(Loc, diag::note_constexpr_invalid_template_arg)
2155 << IsReferenceType << !Designator.Entries.empty() << InvalidBaseKind
2156 << Ident;
2157 return false;
2158 }
2159 }
2160
2161 if (auto *FD = dyn_cast_or_null<FunctionDecl>(BaseVD)) {
2162 if (FD->isConsteval()) {
2163 Info.FFDiag(Loc, diag::note_consteval_address_accessible)
2164 << !Type->isAnyPointerType();
2165 Info.Note(FD->getLocation(), diag::note_declared_at);
2166 return false;
2167 }
2168 }
2169
2170 // Check that the object is a global. Note that the fake 'this' object we
2171 // manufacture when checking potential constant expressions is conservatively
2172 // assumed to be global here.
2173 if (!IsGlobalLValue(Base)) {
2174 if (Info.getLangOpts().CPlusPlus11) {
2175 const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>();
2176 Info.FFDiag(Loc, diag::note_constexpr_non_global, 1)
2177 << IsReferenceType << !Designator.Entries.empty()
2178 << !!VD << VD;
2179
2180 auto *VarD = dyn_cast_or_null<VarDecl>(VD);
2181 if (VarD && VarD->isConstexpr()) {
2182 // Non-static local constexpr variables have unintuitive semantics:
2183 // constexpr int a = 1;
2184 // constexpr const int *p = &a;
2185 // ... is invalid because the address of 'a' is not constant. Suggest
2186 // adding a 'static' in this case.
2187 Info.Note(VarD->getLocation(), diag::note_constexpr_not_static)
2188 << VarD
2189 << FixItHint::CreateInsertion(VarD->getBeginLoc(), "static ");
2190 } else {
2191 NoteLValueLocation(Info, Base);
2192 }
2193 } else {
2194 Info.FFDiag(Loc);
2195 }
2196 // Don't allow references to temporaries to escape.
2197 return false;
2198 }
2199 assert((Info.checkingPotentialConstantExpression() ||
2200 LVal.getLValueCallIndex() == 0) &&
2201 "have call index for global lvalue");
2202
2203 if (Base.is<DynamicAllocLValue>()) {
2204 Info.FFDiag(Loc, diag::note_constexpr_dynamic_alloc)
2205 << IsReferenceType << !Designator.Entries.empty();
2206 NoteLValueLocation(Info, Base);
2207 return false;
2208 }
2209
2210 if (BaseVD) {
2211 if (const VarDecl *Var = dyn_cast<const VarDecl>(BaseVD)) {
2212 // Check if this is a thread-local variable.
2213 if (Var->getTLSKind())
2214 // FIXME: Diagnostic!
2215 return false;
2216
2217 // A dllimport variable never acts like a constant, unless we're
2218 // evaluating a value for use only in name mangling.
2219 if (!isForManglingOnly(Kind) && Var->hasAttr<DLLImportAttr>())
2220 // FIXME: Diagnostic!
2221 return false;
2222 }
2223 if (const auto *FD = dyn_cast<const FunctionDecl>(BaseVD)) {
2224 // __declspec(dllimport) must be handled very carefully:
2225 // We must never initialize an expression with the thunk in C++.
2226 // Doing otherwise would allow the same id-expression to yield
2227 // different addresses for the same function in different translation
2228 // units. However, this means that we must dynamically initialize the
2229 // expression with the contents of the import address table at runtime.
2230 //
2231 // The C language has no notion of ODR; furthermore, it has no notion of
2232 // dynamic initialization. This means that we are permitted to
2233 // perform initialization with the address of the thunk.
2234 if (Info.getLangOpts().CPlusPlus && !isForManglingOnly(Kind) &&
2235 FD->hasAttr<DLLImportAttr>())
2236 // FIXME: Diagnostic!
2237 return false;
2238 }
2239 } else if (const auto *MTE =
2240 dyn_cast_or_null<MaterializeTemporaryExpr>(BaseE)) {
2241 if (CheckedTemps.insert(MTE).second) {
2242 QualType TempType = getType(Base);
2243 if (TempType.isDestructedType()) {
2244 Info.FFDiag(MTE->getExprLoc(),
2245 diag::note_constexpr_unsupported_temporary_nontrivial_dtor)
2246 << TempType;
2247 return false;
2248 }
2249
2250 APValue *V = MTE->getOrCreateValue(false);
2251 assert(V && "evasluation result refers to uninitialised temporary");
2252 if (!CheckEvaluationResult(CheckEvaluationResultKind::ConstantExpression,
2253 Info, MTE->getExprLoc(), TempType, *V,
2254 Kind, SourceLocation(), CheckedTemps))
2255 return false;
2256 }
2257 }
2258
2259 // Allow address constant expressions to be past-the-end pointers. This is
2260 // an extension: the standard requires them to point to an object.
2261 if (!IsReferenceType)
2262 return true;
2263
2264 // A reference constant expression must refer to an object.
2265 if (!Base) {
2266 // FIXME: diagnostic
2267 Info.CCEDiag(Loc);
2268 return true;
2269 }
2270
2271 // Does this refer one past the end of some object?
2272 if (!Designator.Invalid && Designator.isOnePastTheEnd()) {
2273 Info.FFDiag(Loc, diag::note_constexpr_past_end, 1)
2274 << !Designator.Entries.empty() << !!BaseVD << BaseVD;
2275 NoteLValueLocation(Info, Base);
2276 }
2277
2278 return true;
2279 }
2280
2281 /// Member pointers are constant expressions unless they point to a
2282 /// non-virtual dllimport member function.
CheckMemberPointerConstantExpression(EvalInfo & Info,SourceLocation Loc,QualType Type,const APValue & Value,ConstantExprKind Kind)2283 static bool CheckMemberPointerConstantExpression(EvalInfo &Info,
2284 SourceLocation Loc,
2285 QualType Type,
2286 const APValue &Value,
2287 ConstantExprKind Kind) {
2288 const ValueDecl *Member = Value.getMemberPointerDecl();
2289 const auto *FD = dyn_cast_or_null<CXXMethodDecl>(Member);
2290 if (!FD)
2291 return true;
2292 if (FD->isConsteval()) {
2293 Info.FFDiag(Loc, diag::note_consteval_address_accessible) << /*pointer*/ 0;
2294 Info.Note(FD->getLocation(), diag::note_declared_at);
2295 return false;
2296 }
2297 return isForManglingOnly(Kind) || FD->isVirtual() ||
2298 !FD->hasAttr<DLLImportAttr>();
2299 }
2300
2301 /// Check that this core constant expression is of literal type, and if not,
2302 /// produce an appropriate diagnostic.
CheckLiteralType(EvalInfo & Info,const Expr * E,const LValue * This=nullptr)2303 static bool CheckLiteralType(EvalInfo &Info, const Expr *E,
2304 const LValue *This = nullptr) {
2305 if (!E->isPRValue() || E->getType()->isLiteralType(Info.Ctx))
2306 return true;
2307
2308 // C++1y: A constant initializer for an object o [...] may also invoke
2309 // constexpr constructors for o and its subobjects even if those objects
2310 // are of non-literal class types.
2311 //
2312 // C++11 missed this detail for aggregates, so classes like this:
2313 // struct foo_t { union { int i; volatile int j; } u; };
2314 // are not (obviously) initializable like so:
2315 // __attribute__((__require_constant_initialization__))
2316 // static const foo_t x = {{0}};
2317 // because "i" is a subobject with non-literal initialization (due to the
2318 // volatile member of the union). See:
2319 // http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#1677
2320 // Therefore, we use the C++1y behavior.
2321 if (This && Info.EvaluatingDecl == This->getLValueBase())
2322 return true;
2323
2324 // Prvalue constant expressions must be of literal types.
2325 if (Info.getLangOpts().CPlusPlus11)
2326 Info.FFDiag(E, diag::note_constexpr_nonliteral)
2327 << E->getType();
2328 else
2329 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
2330 return false;
2331 }
2332
CheckEvaluationResult(CheckEvaluationResultKind CERK,EvalInfo & Info,SourceLocation DiagLoc,QualType Type,const APValue & Value,ConstantExprKind Kind,SourceLocation SubobjectLoc,CheckedTemporaries & CheckedTemps)2333 static bool CheckEvaluationResult(CheckEvaluationResultKind CERK,
2334 EvalInfo &Info, SourceLocation DiagLoc,
2335 QualType Type, const APValue &Value,
2336 ConstantExprKind Kind,
2337 SourceLocation SubobjectLoc,
2338 CheckedTemporaries &CheckedTemps) {
2339 if (!Value.hasValue()) {
2340 Info.FFDiag(DiagLoc, diag::note_constexpr_uninitialized)
2341 << true << Type;
2342 if (SubobjectLoc.isValid())
2343 Info.Note(SubobjectLoc, diag::note_constexpr_subobject_declared_here);
2344 return false;
2345 }
2346
2347 // We allow _Atomic(T) to be initialized from anything that T can be
2348 // initialized from.
2349 if (const AtomicType *AT = Type->getAs<AtomicType>())
2350 Type = AT->getValueType();
2351
2352 // Core issue 1454: For a literal constant expression of array or class type,
2353 // each subobject of its value shall have been initialized by a constant
2354 // expression.
2355 if (Value.isArray()) {
2356 QualType EltTy = Type->castAsArrayTypeUnsafe()->getElementType();
2357 for (unsigned I = 0, N = Value.getArrayInitializedElts(); I != N; ++I) {
2358 if (!CheckEvaluationResult(CERK, Info, DiagLoc, EltTy,
2359 Value.getArrayInitializedElt(I), Kind,
2360 SubobjectLoc, CheckedTemps))
2361 return false;
2362 }
2363 if (!Value.hasArrayFiller())
2364 return true;
2365 return CheckEvaluationResult(CERK, Info, DiagLoc, EltTy,
2366 Value.getArrayFiller(), Kind, SubobjectLoc,
2367 CheckedTemps);
2368 }
2369 if (Value.isUnion() && Value.getUnionField()) {
2370 return CheckEvaluationResult(
2371 CERK, Info, DiagLoc, Value.getUnionField()->getType(),
2372 Value.getUnionValue(), Kind, Value.getUnionField()->getLocation(),
2373 CheckedTemps);
2374 }
2375 if (Value.isStruct()) {
2376 RecordDecl *RD = Type->castAs<RecordType>()->getDecl();
2377 if (const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(RD)) {
2378 unsigned BaseIndex = 0;
2379 for (const CXXBaseSpecifier &BS : CD->bases()) {
2380 if (!CheckEvaluationResult(CERK, Info, DiagLoc, BS.getType(),
2381 Value.getStructBase(BaseIndex), Kind,
2382 BS.getBeginLoc(), CheckedTemps))
2383 return false;
2384 ++BaseIndex;
2385 }
2386 }
2387 for (const auto *I : RD->fields()) {
2388 if (I->isUnnamedBitfield())
2389 continue;
2390
2391 if (!CheckEvaluationResult(CERK, Info, DiagLoc, I->getType(),
2392 Value.getStructField(I->getFieldIndex()),
2393 Kind, I->getLocation(), CheckedTemps))
2394 return false;
2395 }
2396 }
2397
2398 if (Value.isLValue() &&
2399 CERK == CheckEvaluationResultKind::ConstantExpression) {
2400 LValue LVal;
2401 LVal.setFrom(Info.Ctx, Value);
2402 return CheckLValueConstantExpression(Info, DiagLoc, Type, LVal, Kind,
2403 CheckedTemps);
2404 }
2405
2406 if (Value.isMemberPointer() &&
2407 CERK == CheckEvaluationResultKind::ConstantExpression)
2408 return CheckMemberPointerConstantExpression(Info, DiagLoc, Type, Value, Kind);
2409
2410 // Everything else is fine.
2411 return true;
2412 }
2413
2414 /// Check that this core constant expression value is a valid value for a
2415 /// constant expression. If not, report an appropriate diagnostic. Does not
2416 /// check that the expression is of literal type.
CheckConstantExpression(EvalInfo & Info,SourceLocation DiagLoc,QualType Type,const APValue & Value,ConstantExprKind Kind)2417 static bool CheckConstantExpression(EvalInfo &Info, SourceLocation DiagLoc,
2418 QualType Type, const APValue &Value,
2419 ConstantExprKind Kind) {
2420 // Nothing to check for a constant expression of type 'cv void'.
2421 if (Type->isVoidType())
2422 return true;
2423
2424 CheckedTemporaries CheckedTemps;
2425 return CheckEvaluationResult(CheckEvaluationResultKind::ConstantExpression,
2426 Info, DiagLoc, Type, Value, Kind,
2427 SourceLocation(), CheckedTemps);
2428 }
2429
2430 /// Check that this evaluated value is fully-initialized and can be loaded by
2431 /// an lvalue-to-rvalue conversion.
CheckFullyInitialized(EvalInfo & Info,SourceLocation DiagLoc,QualType Type,const APValue & Value)2432 static bool CheckFullyInitialized(EvalInfo &Info, SourceLocation DiagLoc,
2433 QualType Type, const APValue &Value) {
2434 CheckedTemporaries CheckedTemps;
2435 return CheckEvaluationResult(
2436 CheckEvaluationResultKind::FullyInitialized, Info, DiagLoc, Type, Value,
2437 ConstantExprKind::Normal, SourceLocation(), CheckedTemps);
2438 }
2439
2440 /// Enforce C++2a [expr.const]/4.17, which disallows new-expressions unless
2441 /// "the allocated storage is deallocated within the evaluation".
CheckMemoryLeaks(EvalInfo & Info)2442 static bool CheckMemoryLeaks(EvalInfo &Info) {
2443 if (!Info.HeapAllocs.empty()) {
2444 // We can still fold to a constant despite a compile-time memory leak,
2445 // so long as the heap allocation isn't referenced in the result (we check
2446 // that in CheckConstantExpression).
2447 Info.CCEDiag(Info.HeapAllocs.begin()->second.AllocExpr,
2448 diag::note_constexpr_memory_leak)
2449 << unsigned(Info.HeapAllocs.size() - 1);
2450 }
2451 return true;
2452 }
2453
EvalPointerValueAsBool(const APValue & Value,bool & Result)2454 static bool EvalPointerValueAsBool(const APValue &Value, bool &Result) {
2455 // A null base expression indicates a null pointer. These are always
2456 // evaluatable, and they are false unless the offset is zero.
2457 if (!Value.getLValueBase()) {
2458 Result = !Value.getLValueOffset().isZero();
2459 return true;
2460 }
2461
2462 // We have a non-null base. These are generally known to be true, but if it's
2463 // a weak declaration it can be null at runtime.
2464 Result = true;
2465 const ValueDecl *Decl = Value.getLValueBase().dyn_cast<const ValueDecl*>();
2466 return !Decl || !Decl->isWeak();
2467 }
2468
HandleConversionToBool(const APValue & Val,bool & Result)2469 static bool HandleConversionToBool(const APValue &Val, bool &Result) {
2470 switch (Val.getKind()) {
2471 case APValue::None:
2472 case APValue::Indeterminate:
2473 return false;
2474 case APValue::Int:
2475 Result = Val.getInt().getBoolValue();
2476 return true;
2477 case APValue::FixedPoint:
2478 Result = Val.getFixedPoint().getBoolValue();
2479 return true;
2480 case APValue::Float:
2481 Result = !Val.getFloat().isZero();
2482 return true;
2483 case APValue::ComplexInt:
2484 Result = Val.getComplexIntReal().getBoolValue() ||
2485 Val.getComplexIntImag().getBoolValue();
2486 return true;
2487 case APValue::ComplexFloat:
2488 Result = !Val.getComplexFloatReal().isZero() ||
2489 !Val.getComplexFloatImag().isZero();
2490 return true;
2491 case APValue::LValue:
2492 return EvalPointerValueAsBool(Val, Result);
2493 case APValue::MemberPointer:
2494 Result = Val.getMemberPointerDecl();
2495 return true;
2496 case APValue::Vector:
2497 case APValue::Array:
2498 case APValue::Struct:
2499 case APValue::Union:
2500 case APValue::AddrLabelDiff:
2501 return false;
2502 }
2503
2504 llvm_unreachable("unknown APValue kind");
2505 }
2506
EvaluateAsBooleanCondition(const Expr * E,bool & Result,EvalInfo & Info)2507 static bool EvaluateAsBooleanCondition(const Expr *E, bool &Result,
2508 EvalInfo &Info) {
2509 assert(!E->isValueDependent());
2510 assert(E->isPRValue() && "missing lvalue-to-rvalue conv in bool condition");
2511 APValue Val;
2512 if (!Evaluate(Val, Info, E))
2513 return false;
2514 return HandleConversionToBool(Val, Result);
2515 }
2516
2517 template<typename T>
HandleOverflow(EvalInfo & Info,const Expr * E,const T & SrcValue,QualType DestType)2518 static bool HandleOverflow(EvalInfo &Info, const Expr *E,
2519 const T &SrcValue, QualType DestType) {
2520 Info.CCEDiag(E, diag::note_constexpr_overflow)
2521 << SrcValue << DestType;
2522 return Info.noteUndefinedBehavior();
2523 }
2524
HandleFloatToIntCast(EvalInfo & Info,const Expr * E,QualType SrcType,const APFloat & Value,QualType DestType,APSInt & Result)2525 static bool HandleFloatToIntCast(EvalInfo &Info, const Expr *E,
2526 QualType SrcType, const APFloat &Value,
2527 QualType DestType, APSInt &Result) {
2528 unsigned DestWidth = Info.Ctx.getIntWidth(DestType);
2529 // Determine whether we are converting to unsigned or signed.
2530 bool DestSigned = DestType->isSignedIntegerOrEnumerationType();
2531
2532 Result = APSInt(DestWidth, !DestSigned);
2533 bool ignored;
2534 if (Value.convertToInteger(Result, llvm::APFloat::rmTowardZero, &ignored)
2535 & APFloat::opInvalidOp)
2536 return HandleOverflow(Info, E, Value, DestType);
2537 return true;
2538 }
2539
2540 /// Get rounding mode used for evaluation of the specified expression.
2541 /// \param[out] DynamicRM Is set to true is the requested rounding mode is
2542 /// dynamic.
2543 /// If rounding mode is unknown at compile time, still try to evaluate the
2544 /// expression. If the result is exact, it does not depend on rounding mode.
2545 /// So return "tonearest" mode instead of "dynamic".
getActiveRoundingMode(EvalInfo & Info,const Expr * E,bool & DynamicRM)2546 static llvm::RoundingMode getActiveRoundingMode(EvalInfo &Info, const Expr *E,
2547 bool &DynamicRM) {
2548 llvm::RoundingMode RM =
2549 E->getFPFeaturesInEffect(Info.Ctx.getLangOpts()).getRoundingMode();
2550 DynamicRM = (RM == llvm::RoundingMode::Dynamic);
2551 if (DynamicRM)
2552 RM = llvm::RoundingMode::NearestTiesToEven;
2553 return RM;
2554 }
2555
2556 /// Check if the given evaluation result is allowed for constant evaluation.
checkFloatingPointResult(EvalInfo & Info,const Expr * E,APFloat::opStatus St)2557 static bool checkFloatingPointResult(EvalInfo &Info, const Expr *E,
2558 APFloat::opStatus St) {
2559 // In a constant context, assume that any dynamic rounding mode or FP
2560 // exception state matches the default floating-point environment.
2561 if (Info.InConstantContext)
2562 return true;
2563
2564 FPOptions FPO = E->getFPFeaturesInEffect(Info.Ctx.getLangOpts());
2565 if ((St & APFloat::opInexact) &&
2566 FPO.getRoundingMode() == llvm::RoundingMode::Dynamic) {
2567 // Inexact result means that it depends on rounding mode. If the requested
2568 // mode is dynamic, the evaluation cannot be made in compile time.
2569 Info.FFDiag(E, diag::note_constexpr_dynamic_rounding);
2570 return false;
2571 }
2572
2573 if ((St != APFloat::opOK) &&
2574 (FPO.getRoundingMode() == llvm::RoundingMode::Dynamic ||
2575 FPO.getFPExceptionMode() != LangOptions::FPE_Ignore ||
2576 FPO.getAllowFEnvAccess())) {
2577 Info.FFDiag(E, diag::note_constexpr_float_arithmetic_strict);
2578 return false;
2579 }
2580
2581 if ((St & APFloat::opStatus::opInvalidOp) &&
2582 FPO.getFPExceptionMode() != LangOptions::FPE_Ignore) {
2583 // There is no usefully definable result.
2584 Info.FFDiag(E);
2585 return false;
2586 }
2587
2588 // FIXME: if:
2589 // - evaluation triggered other FP exception, and
2590 // - exception mode is not "ignore", and
2591 // - the expression being evaluated is not a part of global variable
2592 // initializer,
2593 // the evaluation probably need to be rejected.
2594 return true;
2595 }
2596
HandleFloatToFloatCast(EvalInfo & Info,const Expr * E,QualType SrcType,QualType DestType,APFloat & Result)2597 static bool HandleFloatToFloatCast(EvalInfo &Info, const Expr *E,
2598 QualType SrcType, QualType DestType,
2599 APFloat &Result) {
2600 assert(isa<CastExpr>(E) || isa<CompoundAssignOperator>(E));
2601 bool DynamicRM;
2602 llvm::RoundingMode RM = getActiveRoundingMode(Info, E, DynamicRM);
2603 APFloat::opStatus St;
2604 APFloat Value = Result;
2605 bool ignored;
2606 St = Result.convert(Info.Ctx.getFloatTypeSemantics(DestType), RM, &ignored);
2607 return checkFloatingPointResult(Info, E, St);
2608 }
2609
HandleIntToIntCast(EvalInfo & Info,const Expr * E,QualType DestType,QualType SrcType,const APSInt & Value)2610 static APSInt HandleIntToIntCast(EvalInfo &Info, const Expr *E,
2611 QualType DestType, QualType SrcType,
2612 const APSInt &Value) {
2613 unsigned DestWidth = Info.Ctx.getIntWidth(DestType);
2614 // Figure out if this is a truncate, extend or noop cast.
2615 // If the input is signed, do a sign extend, noop, or truncate.
2616 APSInt Result = Value.extOrTrunc(DestWidth);
2617 Result.setIsUnsigned(DestType->isUnsignedIntegerOrEnumerationType());
2618 if (DestType->isBooleanType())
2619 Result = Value.getBoolValue();
2620 return Result;
2621 }
2622
HandleIntToFloatCast(EvalInfo & Info,const Expr * E,const FPOptions FPO,QualType SrcType,const APSInt & Value,QualType DestType,APFloat & Result)2623 static bool HandleIntToFloatCast(EvalInfo &Info, const Expr *E,
2624 const FPOptions FPO,
2625 QualType SrcType, const APSInt &Value,
2626 QualType DestType, APFloat &Result) {
2627 Result = APFloat(Info.Ctx.getFloatTypeSemantics(DestType), 1);
2628 APFloat::opStatus St = Result.convertFromAPInt(Value, Value.isSigned(),
2629 APFloat::rmNearestTiesToEven);
2630 if (!Info.InConstantContext && St != llvm::APFloatBase::opOK &&
2631 FPO.isFPConstrained()) {
2632 Info.FFDiag(E, diag::note_constexpr_float_arithmetic_strict);
2633 return false;
2634 }
2635 return true;
2636 }
2637
truncateBitfieldValue(EvalInfo & Info,const Expr * E,APValue & Value,const FieldDecl * FD)2638 static bool truncateBitfieldValue(EvalInfo &Info, const Expr *E,
2639 APValue &Value, const FieldDecl *FD) {
2640 assert(FD->isBitField() && "truncateBitfieldValue on non-bitfield");
2641
2642 if (!Value.isInt()) {
2643 // Trying to store a pointer-cast-to-integer into a bitfield.
2644 // FIXME: In this case, we should provide the diagnostic for casting
2645 // a pointer to an integer.
2646 assert(Value.isLValue() && "integral value neither int nor lvalue?");
2647 Info.FFDiag(E);
2648 return false;
2649 }
2650
2651 APSInt &Int = Value.getInt();
2652 unsigned OldBitWidth = Int.getBitWidth();
2653 unsigned NewBitWidth = FD->getBitWidthValue(Info.Ctx);
2654 if (NewBitWidth < OldBitWidth)
2655 Int = Int.trunc(NewBitWidth).extend(OldBitWidth);
2656 return true;
2657 }
2658
EvalAndBitcastToAPInt(EvalInfo & Info,const Expr * E,llvm::APInt & Res)2659 static bool EvalAndBitcastToAPInt(EvalInfo &Info, const Expr *E,
2660 llvm::APInt &Res) {
2661 APValue SVal;
2662 if (!Evaluate(SVal, Info, E))
2663 return false;
2664 if (SVal.isInt()) {
2665 Res = SVal.getInt();
2666 return true;
2667 }
2668 if (SVal.isFloat()) {
2669 Res = SVal.getFloat().bitcastToAPInt();
2670 return true;
2671 }
2672 if (SVal.isVector()) {
2673 QualType VecTy = E->getType();
2674 unsigned VecSize = Info.Ctx.getTypeSize(VecTy);
2675 QualType EltTy = VecTy->castAs<VectorType>()->getElementType();
2676 unsigned EltSize = Info.Ctx.getTypeSize(EltTy);
2677 bool BigEndian = Info.Ctx.getTargetInfo().isBigEndian();
2678 Res = llvm::APInt::getZero(VecSize);
2679 for (unsigned i = 0; i < SVal.getVectorLength(); i++) {
2680 APValue &Elt = SVal.getVectorElt(i);
2681 llvm::APInt EltAsInt;
2682 if (Elt.isInt()) {
2683 EltAsInt = Elt.getInt();
2684 } else if (Elt.isFloat()) {
2685 EltAsInt = Elt.getFloat().bitcastToAPInt();
2686 } else {
2687 // Don't try to handle vectors of anything other than int or float
2688 // (not sure if it's possible to hit this case).
2689 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
2690 return false;
2691 }
2692 unsigned BaseEltSize = EltAsInt.getBitWidth();
2693 if (BigEndian)
2694 Res |= EltAsInt.zextOrTrunc(VecSize).rotr(i*EltSize+BaseEltSize);
2695 else
2696 Res |= EltAsInt.zextOrTrunc(VecSize).rotl(i*EltSize);
2697 }
2698 return true;
2699 }
2700 // Give up if the input isn't an int, float, or vector. For example, we
2701 // reject "(v4i16)(intptr_t)&a".
2702 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
2703 return false;
2704 }
2705
2706 /// Perform the given integer operation, which is known to need at most BitWidth
2707 /// bits, and check for overflow in the original type (if that type was not an
2708 /// unsigned type).
2709 template<typename Operation>
CheckedIntArithmetic(EvalInfo & Info,const Expr * E,const APSInt & LHS,const APSInt & RHS,unsigned BitWidth,Operation Op,APSInt & Result)2710 static bool CheckedIntArithmetic(EvalInfo &Info, const Expr *E,
2711 const APSInt &LHS, const APSInt &RHS,
2712 unsigned BitWidth, Operation Op,
2713 APSInt &Result) {
2714 if (LHS.isUnsigned()) {
2715 Result = Op(LHS, RHS);
2716 return true;
2717 }
2718
2719 APSInt Value(Op(LHS.extend(BitWidth), RHS.extend(BitWidth)), false);
2720 Result = Value.trunc(LHS.getBitWidth());
2721 if (Result.extend(BitWidth) != Value) {
2722 if (Info.checkingForUndefinedBehavior())
2723 Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
2724 diag::warn_integer_constant_overflow)
2725 << toString(Result, 10) << E->getType();
2726 return HandleOverflow(Info, E, Value, E->getType());
2727 }
2728 return true;
2729 }
2730
2731 /// Perform the given binary integer operation.
handleIntIntBinOp(EvalInfo & Info,const Expr * E,const APSInt & LHS,BinaryOperatorKind Opcode,APSInt RHS,APSInt & Result)2732 static bool handleIntIntBinOp(EvalInfo &Info, const Expr *E, const APSInt &LHS,
2733 BinaryOperatorKind Opcode, APSInt RHS,
2734 APSInt &Result) {
2735 switch (Opcode) {
2736 default:
2737 Info.FFDiag(E);
2738 return false;
2739 case BO_Mul:
2740 return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() * 2,
2741 std::multiplies<APSInt>(), Result);
2742 case BO_Add:
2743 return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1,
2744 std::plus<APSInt>(), Result);
2745 case BO_Sub:
2746 return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1,
2747 std::minus<APSInt>(), Result);
2748 case BO_And: Result = LHS & RHS; return true;
2749 case BO_Xor: Result = LHS ^ RHS; return true;
2750 case BO_Or: Result = LHS | RHS; return true;
2751 case BO_Div:
2752 case BO_Rem:
2753 if (RHS == 0) {
2754 Info.FFDiag(E, diag::note_expr_divide_by_zero);
2755 return false;
2756 }
2757 Result = (Opcode == BO_Rem ? LHS % RHS : LHS / RHS);
2758 // Check for overflow case: INT_MIN / -1 or INT_MIN % -1. APSInt supports
2759 // this operation and gives the two's complement result.
2760 if (RHS.isNegative() && RHS.isAllOnes() && LHS.isSigned() &&
2761 LHS.isMinSignedValue())
2762 return HandleOverflow(Info, E, -LHS.extend(LHS.getBitWidth() + 1),
2763 E->getType());
2764 return true;
2765 case BO_Shl: {
2766 if (Info.getLangOpts().OpenCL)
2767 // OpenCL 6.3j: shift values are effectively % word size of LHS.
2768 RHS &= APSInt(llvm::APInt(RHS.getBitWidth(),
2769 static_cast<uint64_t>(LHS.getBitWidth() - 1)),
2770 RHS.isUnsigned());
2771 else if (RHS.isSigned() && RHS.isNegative()) {
2772 // During constant-folding, a negative shift is an opposite shift. Such
2773 // a shift is not a constant expression.
2774 Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHS;
2775 RHS = -RHS;
2776 goto shift_right;
2777 }
2778 shift_left:
2779 // C++11 [expr.shift]p1: Shift width must be less than the bit width of
2780 // the shifted type.
2781 unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1);
2782 if (SA != RHS) {
2783 Info.CCEDiag(E, diag::note_constexpr_large_shift)
2784 << RHS << E->getType() << LHS.getBitWidth();
2785 } else if (LHS.isSigned() && !Info.getLangOpts().CPlusPlus20) {
2786 // C++11 [expr.shift]p2: A signed left shift must have a non-negative
2787 // operand, and must not overflow the corresponding unsigned type.
2788 // C++2a [expr.shift]p2: E1 << E2 is the unique value congruent to
2789 // E1 x 2^E2 module 2^N.
2790 if (LHS.isNegative())
2791 Info.CCEDiag(E, diag::note_constexpr_lshift_of_negative) << LHS;
2792 else if (LHS.countLeadingZeros() < SA)
2793 Info.CCEDiag(E, diag::note_constexpr_lshift_discards);
2794 }
2795 Result = LHS << SA;
2796 return true;
2797 }
2798 case BO_Shr: {
2799 if (Info.getLangOpts().OpenCL)
2800 // OpenCL 6.3j: shift values are effectively % word size of LHS.
2801 RHS &= APSInt(llvm::APInt(RHS.getBitWidth(),
2802 static_cast<uint64_t>(LHS.getBitWidth() - 1)),
2803 RHS.isUnsigned());
2804 else if (RHS.isSigned() && RHS.isNegative()) {
2805 // During constant-folding, a negative shift is an opposite shift. Such a
2806 // shift is not a constant expression.
2807 Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHS;
2808 RHS = -RHS;
2809 goto shift_left;
2810 }
2811 shift_right:
2812 // C++11 [expr.shift]p1: Shift width must be less than the bit width of the
2813 // shifted type.
2814 unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1);
2815 if (SA != RHS)
2816 Info.CCEDiag(E, diag::note_constexpr_large_shift)
2817 << RHS << E->getType() << LHS.getBitWidth();
2818 Result = LHS >> SA;
2819 return true;
2820 }
2821
2822 case BO_LT: Result = LHS < RHS; return true;
2823 case BO_GT: Result = LHS > RHS; return true;
2824 case BO_LE: Result = LHS <= RHS; return true;
2825 case BO_GE: Result = LHS >= RHS; return true;
2826 case BO_EQ: Result = LHS == RHS; return true;
2827 case BO_NE: Result = LHS != RHS; return true;
2828 case BO_Cmp:
2829 llvm_unreachable("BO_Cmp should be handled elsewhere");
2830 }
2831 }
2832
2833 /// Perform the given binary floating-point operation, in-place, on LHS.
handleFloatFloatBinOp(EvalInfo & Info,const BinaryOperator * E,APFloat & LHS,BinaryOperatorKind Opcode,const APFloat & RHS)2834 static bool handleFloatFloatBinOp(EvalInfo &Info, const BinaryOperator *E,
2835 APFloat &LHS, BinaryOperatorKind Opcode,
2836 const APFloat &RHS) {
2837 bool DynamicRM;
2838 llvm::RoundingMode RM = getActiveRoundingMode(Info, E, DynamicRM);
2839 APFloat::opStatus St;
2840 switch (Opcode) {
2841 default:
2842 Info.FFDiag(E);
2843 return false;
2844 case BO_Mul:
2845 St = LHS.multiply(RHS, RM);
2846 break;
2847 case BO_Add:
2848 St = LHS.add(RHS, RM);
2849 break;
2850 case BO_Sub:
2851 St = LHS.subtract(RHS, RM);
2852 break;
2853 case BO_Div:
2854 // [expr.mul]p4:
2855 // If the second operand of / or % is zero the behavior is undefined.
2856 if (RHS.isZero())
2857 Info.CCEDiag(E, diag::note_expr_divide_by_zero);
2858 St = LHS.divide(RHS, RM);
2859 break;
2860 }
2861
2862 // [expr.pre]p4:
2863 // If during the evaluation of an expression, the result is not
2864 // mathematically defined [...], the behavior is undefined.
2865 // FIXME: C++ rules require us to not conform to IEEE 754 here.
2866 if (LHS.isNaN()) {
2867 Info.CCEDiag(E, diag::note_constexpr_float_arithmetic) << LHS.isNaN();
2868 return Info.noteUndefinedBehavior();
2869 }
2870
2871 return checkFloatingPointResult(Info, E, St);
2872 }
2873
handleLogicalOpForVector(const APInt & LHSValue,BinaryOperatorKind Opcode,const APInt & RHSValue,APInt & Result)2874 static bool handleLogicalOpForVector(const APInt &LHSValue,
2875 BinaryOperatorKind Opcode,
2876 const APInt &RHSValue, APInt &Result) {
2877 bool LHS = (LHSValue != 0);
2878 bool RHS = (RHSValue != 0);
2879
2880 if (Opcode == BO_LAnd)
2881 Result = LHS && RHS;
2882 else
2883 Result = LHS || RHS;
2884 return true;
2885 }
handleLogicalOpForVector(const APFloat & LHSValue,BinaryOperatorKind Opcode,const APFloat & RHSValue,APInt & Result)2886 static bool handleLogicalOpForVector(const APFloat &LHSValue,
2887 BinaryOperatorKind Opcode,
2888 const APFloat &RHSValue, APInt &Result) {
2889 bool LHS = !LHSValue.isZero();
2890 bool RHS = !RHSValue.isZero();
2891
2892 if (Opcode == BO_LAnd)
2893 Result = LHS && RHS;
2894 else
2895 Result = LHS || RHS;
2896 return true;
2897 }
2898
handleLogicalOpForVector(const APValue & LHSValue,BinaryOperatorKind Opcode,const APValue & RHSValue,APInt & Result)2899 static bool handleLogicalOpForVector(const APValue &LHSValue,
2900 BinaryOperatorKind Opcode,
2901 const APValue &RHSValue, APInt &Result) {
2902 // The result is always an int type, however operands match the first.
2903 if (LHSValue.getKind() == APValue::Int)
2904 return handleLogicalOpForVector(LHSValue.getInt(), Opcode,
2905 RHSValue.getInt(), Result);
2906 assert(LHSValue.getKind() == APValue::Float && "Should be no other options");
2907 return handleLogicalOpForVector(LHSValue.getFloat(), Opcode,
2908 RHSValue.getFloat(), Result);
2909 }
2910
2911 template <typename APTy>
2912 static bool
handleCompareOpForVectorHelper(const APTy & LHSValue,BinaryOperatorKind Opcode,const APTy & RHSValue,APInt & Result)2913 handleCompareOpForVectorHelper(const APTy &LHSValue, BinaryOperatorKind Opcode,
2914 const APTy &RHSValue, APInt &Result) {
2915 switch (Opcode) {
2916 default:
2917 llvm_unreachable("unsupported binary operator");
2918 case BO_EQ:
2919 Result = (LHSValue == RHSValue);
2920 break;
2921 case BO_NE:
2922 Result = (LHSValue != RHSValue);
2923 break;
2924 case BO_LT:
2925 Result = (LHSValue < RHSValue);
2926 break;
2927 case BO_GT:
2928 Result = (LHSValue > RHSValue);
2929 break;
2930 case BO_LE:
2931 Result = (LHSValue <= RHSValue);
2932 break;
2933 case BO_GE:
2934 Result = (LHSValue >= RHSValue);
2935 break;
2936 }
2937
2938 return true;
2939 }
2940
handleCompareOpForVector(const APValue & LHSValue,BinaryOperatorKind Opcode,const APValue & RHSValue,APInt & Result)2941 static bool handleCompareOpForVector(const APValue &LHSValue,
2942 BinaryOperatorKind Opcode,
2943 const APValue &RHSValue, APInt &Result) {
2944 // The result is always an int type, however operands match the first.
2945 if (LHSValue.getKind() == APValue::Int)
2946 return handleCompareOpForVectorHelper(LHSValue.getInt(), Opcode,
2947 RHSValue.getInt(), Result);
2948 assert(LHSValue.getKind() == APValue::Float && "Should be no other options");
2949 return handleCompareOpForVectorHelper(LHSValue.getFloat(), Opcode,
2950 RHSValue.getFloat(), Result);
2951 }
2952
2953 // Perform binary operations for vector types, in place on the LHS.
handleVectorVectorBinOp(EvalInfo & Info,const BinaryOperator * E,BinaryOperatorKind Opcode,APValue & LHSValue,const APValue & RHSValue)2954 static bool handleVectorVectorBinOp(EvalInfo &Info, const BinaryOperator *E,
2955 BinaryOperatorKind Opcode,
2956 APValue &LHSValue,
2957 const APValue &RHSValue) {
2958 assert(Opcode != BO_PtrMemD && Opcode != BO_PtrMemI &&
2959 "Operation not supported on vector types");
2960
2961 const auto *VT = E->getType()->castAs<VectorType>();
2962 unsigned NumElements = VT->getNumElements();
2963 QualType EltTy = VT->getElementType();
2964
2965 // In the cases (typically C as I've observed) where we aren't evaluating
2966 // constexpr but are checking for cases where the LHS isn't yet evaluatable,
2967 // just give up.
2968 if (!LHSValue.isVector()) {
2969 assert(LHSValue.isLValue() &&
2970 "A vector result that isn't a vector OR uncalculated LValue");
2971 Info.FFDiag(E);
2972 return false;
2973 }
2974
2975 assert(LHSValue.getVectorLength() == NumElements &&
2976 RHSValue.getVectorLength() == NumElements && "Different vector sizes");
2977
2978 SmallVector<APValue, 4> ResultElements;
2979
2980 for (unsigned EltNum = 0; EltNum < NumElements; ++EltNum) {
2981 APValue LHSElt = LHSValue.getVectorElt(EltNum);
2982 APValue RHSElt = RHSValue.getVectorElt(EltNum);
2983
2984 if (EltTy->isIntegerType()) {
2985 APSInt EltResult{Info.Ctx.getIntWidth(EltTy),
2986 EltTy->isUnsignedIntegerType()};
2987 bool Success = true;
2988
2989 if (BinaryOperator::isLogicalOp(Opcode))
2990 Success = handleLogicalOpForVector(LHSElt, Opcode, RHSElt, EltResult);
2991 else if (BinaryOperator::isComparisonOp(Opcode))
2992 Success = handleCompareOpForVector(LHSElt, Opcode, RHSElt, EltResult);
2993 else
2994 Success = handleIntIntBinOp(Info, E, LHSElt.getInt(), Opcode,
2995 RHSElt.getInt(), EltResult);
2996
2997 if (!Success) {
2998 Info.FFDiag(E);
2999 return false;
3000 }
3001 ResultElements.emplace_back(EltResult);
3002
3003 } else if (EltTy->isFloatingType()) {
3004 assert(LHSElt.getKind() == APValue::Float &&
3005 RHSElt.getKind() == APValue::Float &&
3006 "Mismatched LHS/RHS/Result Type");
3007 APFloat LHSFloat = LHSElt.getFloat();
3008
3009 if (!handleFloatFloatBinOp(Info, E, LHSFloat, Opcode,
3010 RHSElt.getFloat())) {
3011 Info.FFDiag(E);
3012 return false;
3013 }
3014
3015 ResultElements.emplace_back(LHSFloat);
3016 }
3017 }
3018
3019 LHSValue = APValue(ResultElements.data(), ResultElements.size());
3020 return true;
3021 }
3022
3023 /// Cast an lvalue referring to a base subobject to a derived class, by
3024 /// truncating the lvalue's path to the given length.
CastToDerivedClass(EvalInfo & Info,const Expr * E,LValue & Result,const RecordDecl * TruncatedType,unsigned TruncatedElements)3025 static bool CastToDerivedClass(EvalInfo &Info, const Expr *E, LValue &Result,
3026 const RecordDecl *TruncatedType,
3027 unsigned TruncatedElements) {
3028 SubobjectDesignator &D = Result.Designator;
3029
3030 // Check we actually point to a derived class object.
3031 if (TruncatedElements == D.Entries.size())
3032 return true;
3033 assert(TruncatedElements >= D.MostDerivedPathLength &&
3034 "not casting to a derived class");
3035 if (!Result.checkSubobject(Info, E, CSK_Derived))
3036 return false;
3037
3038 // Truncate the path to the subobject, and remove any derived-to-base offsets.
3039 const RecordDecl *RD = TruncatedType;
3040 for (unsigned I = TruncatedElements, N = D.Entries.size(); I != N; ++I) {
3041 if (RD->isInvalidDecl()) return false;
3042 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
3043 const CXXRecordDecl *Base = getAsBaseClass(D.Entries[I]);
3044 if (isVirtualBaseClass(D.Entries[I]))
3045 Result.Offset -= Layout.getVBaseClassOffset(Base);
3046 else
3047 Result.Offset -= Layout.getBaseClassOffset(Base);
3048 RD = Base;
3049 }
3050 D.Entries.resize(TruncatedElements);
3051 return true;
3052 }
3053
HandleLValueDirectBase(EvalInfo & Info,const Expr * E,LValue & Obj,const CXXRecordDecl * Derived,const CXXRecordDecl * Base,const ASTRecordLayout * RL=nullptr)3054 static bool HandleLValueDirectBase(EvalInfo &Info, const Expr *E, LValue &Obj,
3055 const CXXRecordDecl *Derived,
3056 const CXXRecordDecl *Base,
3057 const ASTRecordLayout *RL = nullptr) {
3058 if (!RL) {
3059 if (Derived->isInvalidDecl()) return false;
3060 RL = &Info.Ctx.getASTRecordLayout(Derived);
3061 }
3062
3063 Obj.getLValueOffset() += RL->getBaseClassOffset(Base);
3064 Obj.addDecl(Info, E, Base, /*Virtual*/ false);
3065 return true;
3066 }
3067
HandleLValueBase(EvalInfo & Info,const Expr * E,LValue & Obj,const CXXRecordDecl * DerivedDecl,const CXXBaseSpecifier * Base)3068 static bool HandleLValueBase(EvalInfo &Info, const Expr *E, LValue &Obj,
3069 const CXXRecordDecl *DerivedDecl,
3070 const CXXBaseSpecifier *Base) {
3071 const CXXRecordDecl *BaseDecl = Base->getType()->getAsCXXRecordDecl();
3072
3073 if (!Base->isVirtual())
3074 return HandleLValueDirectBase(Info, E, Obj, DerivedDecl, BaseDecl);
3075
3076 SubobjectDesignator &D = Obj.Designator;
3077 if (D.Invalid)
3078 return false;
3079
3080 // Extract most-derived object and corresponding type.
3081 DerivedDecl = D.MostDerivedType->getAsCXXRecordDecl();
3082 if (!CastToDerivedClass(Info, E, Obj, DerivedDecl, D.MostDerivedPathLength))
3083 return false;
3084
3085 // Find the virtual base class.
3086 if (DerivedDecl->isInvalidDecl()) return false;
3087 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(DerivedDecl);
3088 Obj.getLValueOffset() += Layout.getVBaseClassOffset(BaseDecl);
3089 Obj.addDecl(Info, E, BaseDecl, /*Virtual*/ true);
3090 return true;
3091 }
3092
HandleLValueBasePath(EvalInfo & Info,const CastExpr * E,QualType Type,LValue & Result)3093 static bool HandleLValueBasePath(EvalInfo &Info, const CastExpr *E,
3094 QualType Type, LValue &Result) {
3095 for (CastExpr::path_const_iterator PathI = E->path_begin(),
3096 PathE = E->path_end();
3097 PathI != PathE; ++PathI) {
3098 if (!HandleLValueBase(Info, E, Result, Type->getAsCXXRecordDecl(),
3099 *PathI))
3100 return false;
3101 Type = (*PathI)->getType();
3102 }
3103 return true;
3104 }
3105
3106 /// 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)3107 static bool CastToBaseClass(EvalInfo &Info, const Expr *E, LValue &Result,
3108 const CXXRecordDecl *DerivedRD,
3109 const CXXRecordDecl *BaseRD) {
3110 CXXBasePaths Paths(/*FindAmbiguities=*/false,
3111 /*RecordPaths=*/true, /*DetectVirtual=*/false);
3112 if (!DerivedRD->isDerivedFrom(BaseRD, Paths))
3113 llvm_unreachable("Class must be derived from the passed in base class!");
3114
3115 for (CXXBasePathElement &Elem : Paths.front())
3116 if (!HandleLValueBase(Info, E, Result, Elem.Class, Elem.Base))
3117 return false;
3118 return true;
3119 }
3120
3121 /// Update LVal to refer to the given field, which must be a member of the type
3122 /// currently described by LVal.
HandleLValueMember(EvalInfo & Info,const Expr * E,LValue & LVal,const FieldDecl * FD,const ASTRecordLayout * RL=nullptr)3123 static bool HandleLValueMember(EvalInfo &Info, const Expr *E, LValue &LVal,
3124 const FieldDecl *FD,
3125 const ASTRecordLayout *RL = nullptr) {
3126 if (!RL) {
3127 if (FD->getParent()->isInvalidDecl()) return false;
3128 RL = &Info.Ctx.getASTRecordLayout(FD->getParent());
3129 }
3130
3131 unsigned I = FD->getFieldIndex();
3132 LVal.adjustOffset(Info.Ctx.toCharUnitsFromBits(RL->getFieldOffset(I)));
3133 LVal.addDecl(Info, E, FD);
3134 return true;
3135 }
3136
3137 /// Update LVal to refer to the given indirect field.
HandleLValueIndirectMember(EvalInfo & Info,const Expr * E,LValue & LVal,const IndirectFieldDecl * IFD)3138 static bool HandleLValueIndirectMember(EvalInfo &Info, const Expr *E,
3139 LValue &LVal,
3140 const IndirectFieldDecl *IFD) {
3141 for (const auto *C : IFD->chain())
3142 if (!HandleLValueMember(Info, E, LVal, cast<FieldDecl>(C)))
3143 return false;
3144 return true;
3145 }
3146
3147 /// Get the size of the given type in char units.
HandleSizeof(EvalInfo & Info,SourceLocation Loc,QualType Type,CharUnits & Size)3148 static bool HandleSizeof(EvalInfo &Info, SourceLocation Loc,
3149 QualType Type, CharUnits &Size) {
3150 // sizeof(void), __alignof__(void), sizeof(function) = 1 as a gcc
3151 // extension.
3152 if (Type->isVoidType() || Type->isFunctionType()) {
3153 Size = CharUnits::One();
3154 return true;
3155 }
3156
3157 if (Type->isDependentType()) {
3158 Info.FFDiag(Loc);
3159 return false;
3160 }
3161
3162 if (!Type->isConstantSizeType()) {
3163 // sizeof(vla) is not a constantexpr: C99 6.5.3.4p2.
3164 // FIXME: Better diagnostic.
3165 Info.FFDiag(Loc);
3166 return false;
3167 }
3168
3169 Size = Info.Ctx.getTypeSizeInChars(Type);
3170 return true;
3171 }
3172
3173 /// Update a pointer value to model pointer arithmetic.
3174 /// \param Info - Information about the ongoing evaluation.
3175 /// \param E - The expression being evaluated, for diagnostic purposes.
3176 /// \param LVal - The pointer value to be updated.
3177 /// \param EltTy - The pointee type represented by LVal.
3178 /// \param Adjustment - The adjustment, in objects of type EltTy, to add.
HandleLValueArrayAdjustment(EvalInfo & Info,const Expr * E,LValue & LVal,QualType EltTy,APSInt Adjustment)3179 static bool HandleLValueArrayAdjustment(EvalInfo &Info, const Expr *E,
3180 LValue &LVal, QualType EltTy,
3181 APSInt Adjustment) {
3182 CharUnits SizeOfPointee;
3183 if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfPointee))
3184 return false;
3185
3186 LVal.adjustOffsetAndIndex(Info, E, Adjustment, SizeOfPointee);
3187 return true;
3188 }
3189
HandleLValueArrayAdjustment(EvalInfo & Info,const Expr * E,LValue & LVal,QualType EltTy,int64_t Adjustment)3190 static bool HandleLValueArrayAdjustment(EvalInfo &Info, const Expr *E,
3191 LValue &LVal, QualType EltTy,
3192 int64_t Adjustment) {
3193 return HandleLValueArrayAdjustment(Info, E, LVal, EltTy,
3194 APSInt::get(Adjustment));
3195 }
3196
3197 /// Update an lvalue to refer to a component of a complex number.
3198 /// \param Info - Information about the ongoing evaluation.
3199 /// \param LVal - The lvalue to be updated.
3200 /// \param EltTy - The complex number's component type.
3201 /// \param Imag - False for the real component, true for the imaginary.
HandleLValueComplexElement(EvalInfo & Info,const Expr * E,LValue & LVal,QualType EltTy,bool Imag)3202 static bool HandleLValueComplexElement(EvalInfo &Info, const Expr *E,
3203 LValue &LVal, QualType EltTy,
3204 bool Imag) {
3205 if (Imag) {
3206 CharUnits SizeOfComponent;
3207 if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfComponent))
3208 return false;
3209 LVal.Offset += SizeOfComponent;
3210 }
3211 LVal.addComplex(Info, E, EltTy, Imag);
3212 return true;
3213 }
3214
3215 /// Try to evaluate the initializer for a variable declaration.
3216 ///
3217 /// \param Info Information about the ongoing evaluation.
3218 /// \param E An expression to be used when printing diagnostics.
3219 /// \param VD The variable whose initializer should be obtained.
3220 /// \param Version The version of the variable within the frame.
3221 /// \param Frame The frame in which the variable was created. Must be null
3222 /// if this variable is not local to the evaluation.
3223 /// \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)3224 static bool evaluateVarDeclInit(EvalInfo &Info, const Expr *E,
3225 const VarDecl *VD, CallStackFrame *Frame,
3226 unsigned Version, APValue *&Result) {
3227 APValue::LValueBase Base(VD, Frame ? Frame->Index : 0, Version);
3228
3229 // If this is a local variable, dig out its value.
3230 if (Frame) {
3231 Result = Frame->getTemporary(VD, Version);
3232 if (Result)
3233 return true;
3234
3235 if (!isa<ParmVarDecl>(VD)) {
3236 // Assume variables referenced within a lambda's call operator that were
3237 // not declared within the call operator are captures and during checking
3238 // of a potential constant expression, assume they are unknown constant
3239 // expressions.
3240 assert(isLambdaCallOperator(Frame->Callee) &&
3241 (VD->getDeclContext() != Frame->Callee || VD->isInitCapture()) &&
3242 "missing value for local variable");
3243 if (Info.checkingPotentialConstantExpression())
3244 return false;
3245 // FIXME: This diagnostic is bogus; we do support captures. Is this code
3246 // still reachable at all?
3247 Info.FFDiag(E->getBeginLoc(),
3248 diag::note_unimplemented_constexpr_lambda_feature_ast)
3249 << "captures not currently allowed";
3250 return false;
3251 }
3252 }
3253
3254 // If we're currently evaluating the initializer of this declaration, use that
3255 // in-flight value.
3256 if (Info.EvaluatingDecl == Base) {
3257 Result = Info.EvaluatingDeclValue;
3258 return true;
3259 }
3260
3261 if (isa<ParmVarDecl>(VD)) {
3262 // Assume parameters of a potential constant expression are usable in
3263 // constant expressions.
3264 if (!Info.checkingPotentialConstantExpression() ||
3265 !Info.CurrentCall->Callee ||
3266 !Info.CurrentCall->Callee->Equals(VD->getDeclContext())) {
3267 if (Info.getLangOpts().CPlusPlus11) {
3268 Info.FFDiag(E, diag::note_constexpr_function_param_value_unknown)
3269 << VD;
3270 NoteLValueLocation(Info, Base);
3271 } else {
3272 Info.FFDiag(E);
3273 }
3274 }
3275 return false;
3276 }
3277
3278 // Dig out the initializer, and use the declaration which it's attached to.
3279 // FIXME: We should eventually check whether the variable has a reachable
3280 // initializing declaration.
3281 const Expr *Init = VD->getAnyInitializer(VD);
3282 if (!Init) {
3283 // Don't diagnose during potential constant expression checking; an
3284 // initializer might be added later.
3285 if (!Info.checkingPotentialConstantExpression()) {
3286 Info.FFDiag(E, diag::note_constexpr_var_init_unknown, 1)
3287 << VD;
3288 NoteLValueLocation(Info, Base);
3289 }
3290 return false;
3291 }
3292
3293 if (Init->isValueDependent()) {
3294 // The DeclRefExpr is not value-dependent, but the variable it refers to
3295 // has a value-dependent initializer. This should only happen in
3296 // constant-folding cases, where the variable is not actually of a suitable
3297 // type for use in a constant expression (otherwise the DeclRefExpr would
3298 // have been value-dependent too), so diagnose that.
3299 assert(!VD->mightBeUsableInConstantExpressions(Info.Ctx));
3300 if (!Info.checkingPotentialConstantExpression()) {
3301 Info.FFDiag(E, Info.getLangOpts().CPlusPlus11
3302 ? diag::note_constexpr_ltor_non_constexpr
3303 : diag::note_constexpr_ltor_non_integral, 1)
3304 << VD << VD->getType();
3305 NoteLValueLocation(Info, Base);
3306 }
3307 return false;
3308 }
3309
3310 // Check that we can fold the initializer. In C++, we will have already done
3311 // this in the cases where it matters for conformance.
3312 if (!VD->evaluateValue()) {
3313 Info.FFDiag(E, diag::note_constexpr_var_init_non_constant, 1) << VD;
3314 NoteLValueLocation(Info, Base);
3315 return false;
3316 }
3317
3318 // Check that the variable is actually usable in constant expressions. For a
3319 // const integral variable or a reference, we might have a non-constant
3320 // initializer that we can nonetheless evaluate the initializer for. Such
3321 // variables are not usable in constant expressions. In C++98, the
3322 // initializer also syntactically needs to be an ICE.
3323 //
3324 // FIXME: We don't diagnose cases that aren't potentially usable in constant
3325 // expressions here; doing so would regress diagnostics for things like
3326 // reading from a volatile constexpr variable.
3327 if ((Info.getLangOpts().CPlusPlus && !VD->hasConstantInitialization() &&
3328 VD->mightBeUsableInConstantExpressions(Info.Ctx)) ||
3329 ((Info.getLangOpts().CPlusPlus || Info.getLangOpts().OpenCL) &&
3330 !Info.getLangOpts().CPlusPlus11 && !VD->hasICEInitializer(Info.Ctx))) {
3331 Info.CCEDiag(E, diag::note_constexpr_var_init_non_constant, 1) << VD;
3332 NoteLValueLocation(Info, Base);
3333 }
3334
3335 // Never use the initializer of a weak variable, not even for constant
3336 // folding. We can't be sure that this is the definition that will be used.
3337 if (VD->isWeak()) {
3338 Info.FFDiag(E, diag::note_constexpr_var_init_weak) << VD;
3339 NoteLValueLocation(Info, Base);
3340 return false;
3341 }
3342
3343 Result = VD->getEvaluatedValue();
3344 return true;
3345 }
3346
3347 /// Get the base index of the given base class within an APValue representing
3348 /// the given derived class.
getBaseIndex(const CXXRecordDecl * Derived,const CXXRecordDecl * Base)3349 static unsigned getBaseIndex(const CXXRecordDecl *Derived,
3350 const CXXRecordDecl *Base) {
3351 Base = Base->getCanonicalDecl();
3352 unsigned Index = 0;
3353 for (CXXRecordDecl::base_class_const_iterator I = Derived->bases_begin(),
3354 E = Derived->bases_end(); I != E; ++I, ++Index) {
3355 if (I->getType()->getAsCXXRecordDecl()->getCanonicalDecl() == Base)
3356 return Index;
3357 }
3358
3359 llvm_unreachable("base class missing from derived class's bases list");
3360 }
3361
3362 /// Extract the value of a character from a string literal.
extractStringLiteralCharacter(EvalInfo & Info,const Expr * Lit,uint64_t Index)3363 static APSInt extractStringLiteralCharacter(EvalInfo &Info, const Expr *Lit,
3364 uint64_t Index) {
3365 assert(!isa<SourceLocExpr>(Lit) &&
3366 "SourceLocExpr should have already been converted to a StringLiteral");
3367
3368 // FIXME: Support MakeStringConstant
3369 if (const auto *ObjCEnc = dyn_cast<ObjCEncodeExpr>(Lit)) {
3370 std::string Str;
3371 Info.Ctx.getObjCEncodingForType(ObjCEnc->getEncodedType(), Str);
3372 assert(Index <= Str.size() && "Index too large");
3373 return APSInt::getUnsigned(Str.c_str()[Index]);
3374 }
3375
3376 if (auto PE = dyn_cast<PredefinedExpr>(Lit))
3377 Lit = PE->getFunctionName();
3378 const StringLiteral *S = cast<StringLiteral>(Lit);
3379 const ConstantArrayType *CAT =
3380 Info.Ctx.getAsConstantArrayType(S->getType());
3381 assert(CAT && "string literal isn't an array");
3382 QualType CharType = CAT->getElementType();
3383 assert(CharType->isIntegerType() && "unexpected character type");
3384
3385 APSInt Value(S->getCharByteWidth() * Info.Ctx.getCharWidth(),
3386 CharType->isUnsignedIntegerType());
3387 if (Index < S->getLength())
3388 Value = S->getCodeUnit(Index);
3389 return Value;
3390 }
3391
3392 // Expand a string literal into an array of characters.
3393 //
3394 // FIXME: This is inefficient; we should probably introduce something similar
3395 // to the LLVM ConstantDataArray to make this cheaper.
expandStringLiteral(EvalInfo & Info,const StringLiteral * S,APValue & Result,QualType AllocType=QualType ())3396 static void expandStringLiteral(EvalInfo &Info, const StringLiteral *S,
3397 APValue &Result,
3398 QualType AllocType = QualType()) {
3399 const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(
3400 AllocType.isNull() ? S->getType() : AllocType);
3401 assert(CAT && "string literal isn't an array");
3402 QualType CharType = CAT->getElementType();
3403 assert(CharType->isIntegerType() && "unexpected character type");
3404
3405 unsigned Elts = CAT->getSize().getZExtValue();
3406 Result = APValue(APValue::UninitArray(),
3407 std::min(S->getLength(), Elts), Elts);
3408 APSInt Value(S->getCharByteWidth() * Info.Ctx.getCharWidth(),
3409 CharType->isUnsignedIntegerType());
3410 if (Result.hasArrayFiller())
3411 Result.getArrayFiller() = APValue(Value);
3412 for (unsigned I = 0, N = Result.getArrayInitializedElts(); I != N; ++I) {
3413 Value = S->getCodeUnit(I);
3414 Result.getArrayInitializedElt(I) = APValue(Value);
3415 }
3416 }
3417
3418 // Expand an array so that it has more than Index filled elements.
expandArray(APValue & Array,unsigned Index)3419 static void expandArray(APValue &Array, unsigned Index) {
3420 unsigned Size = Array.getArraySize();
3421 assert(Index < Size);
3422
3423 // Always at least double the number of elements for which we store a value.
3424 unsigned OldElts = Array.getArrayInitializedElts();
3425 unsigned NewElts = std::max(Index+1, OldElts * 2);
3426 NewElts = std::min(Size, std::max(NewElts, 8u));
3427
3428 // Copy the data across.
3429 APValue NewValue(APValue::UninitArray(), NewElts, Size);
3430 for (unsigned I = 0; I != OldElts; ++I)
3431 NewValue.getArrayInitializedElt(I).swap(Array.getArrayInitializedElt(I));
3432 for (unsigned I = OldElts; I != NewElts; ++I)
3433 NewValue.getArrayInitializedElt(I) = Array.getArrayFiller();
3434 if (NewValue.hasArrayFiller())
3435 NewValue.getArrayFiller() = Array.getArrayFiller();
3436 Array.swap(NewValue);
3437 }
3438
3439 /// Determine whether a type would actually be read by an lvalue-to-rvalue
3440 /// conversion. If it's of class type, we may assume that the copy operation
3441 /// is trivial. Note that this is never true for a union type with fields
3442 /// (because the copy always "reads" the active member) and always true for
3443 /// a non-class type.
3444 static bool isReadByLvalueToRvalueConversion(const CXXRecordDecl *RD);
isReadByLvalueToRvalueConversion(QualType T)3445 static bool isReadByLvalueToRvalueConversion(QualType T) {
3446 CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
3447 return !RD || isReadByLvalueToRvalueConversion(RD);
3448 }
isReadByLvalueToRvalueConversion(const CXXRecordDecl * RD)3449 static bool isReadByLvalueToRvalueConversion(const CXXRecordDecl *RD) {
3450 // FIXME: A trivial copy of a union copies the object representation, even if
3451 // the union is empty.
3452 if (RD->isUnion())
3453 return !RD->field_empty();
3454 if (RD->isEmpty())
3455 return false;
3456
3457 for (auto *Field : RD->fields())
3458 if (!Field->isUnnamedBitfield() &&
3459 isReadByLvalueToRvalueConversion(Field->getType()))
3460 return true;
3461
3462 for (auto &BaseSpec : RD->bases())
3463 if (isReadByLvalueToRvalueConversion(BaseSpec.getType()))
3464 return true;
3465
3466 return false;
3467 }
3468
3469 /// Diagnose an attempt to read from any unreadable field within the specified
3470 /// type, which might be a class type.
diagnoseMutableFields(EvalInfo & Info,const Expr * E,AccessKinds AK,QualType T)3471 static bool diagnoseMutableFields(EvalInfo &Info, const Expr *E, AccessKinds AK,
3472 QualType T) {
3473 CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
3474 if (!RD)
3475 return false;
3476
3477 if (!RD->hasMutableFields())
3478 return false;
3479
3480 for (auto *Field : RD->fields()) {
3481 // If we're actually going to read this field in some way, then it can't
3482 // be mutable. If we're in a union, then assigning to a mutable field
3483 // (even an empty one) can change the active member, so that's not OK.
3484 // FIXME: Add core issue number for the union case.
3485 if (Field->isMutable() &&
3486 (RD->isUnion() || isReadByLvalueToRvalueConversion(Field->getType()))) {
3487 Info.FFDiag(E, diag::note_constexpr_access_mutable, 1) << AK << Field;
3488 Info.Note(Field->getLocation(), diag::note_declared_at);
3489 return true;
3490 }
3491
3492 if (diagnoseMutableFields(Info, E, AK, Field->getType()))
3493 return true;
3494 }
3495
3496 for (auto &BaseSpec : RD->bases())
3497 if (diagnoseMutableFields(Info, E, AK, BaseSpec.getType()))
3498 return true;
3499
3500 // All mutable fields were empty, and thus not actually read.
3501 return false;
3502 }
3503
lifetimeStartedInEvaluation(EvalInfo & Info,APValue::LValueBase Base,bool MutableSubobject=false)3504 static bool lifetimeStartedInEvaluation(EvalInfo &Info,
3505 APValue::LValueBase Base,
3506 bool MutableSubobject = false) {
3507 // A temporary or transient heap allocation we created.
3508 if (Base.getCallIndex() || Base.is<DynamicAllocLValue>())
3509 return true;
3510
3511 switch (Info.IsEvaluatingDecl) {
3512 case EvalInfo::EvaluatingDeclKind::None:
3513 return false;
3514
3515 case EvalInfo::EvaluatingDeclKind::Ctor:
3516 // The variable whose initializer we're evaluating.
3517 if (Info.EvaluatingDecl == Base)
3518 return true;
3519
3520 // A temporary lifetime-extended by the variable whose initializer we're
3521 // evaluating.
3522 if (auto *BaseE = Base.dyn_cast<const Expr *>())
3523 if (auto *BaseMTE = dyn_cast<MaterializeTemporaryExpr>(BaseE))
3524 return Info.EvaluatingDecl == BaseMTE->getExtendingDecl();
3525 return false;
3526
3527 case EvalInfo::EvaluatingDeclKind::Dtor:
3528 // C++2a [expr.const]p6:
3529 // [during constant destruction] the lifetime of a and its non-mutable
3530 // subobjects (but not its mutable subobjects) [are] considered to start
3531 // within e.
3532 if (MutableSubobject || Base != Info.EvaluatingDecl)
3533 return false;
3534 // FIXME: We can meaningfully extend this to cover non-const objects, but
3535 // we will need special handling: we should be able to access only
3536 // subobjects of such objects that are themselves declared const.
3537 QualType T = getType(Base);
3538 return T.isConstQualified() || T->isReferenceType();
3539 }
3540
3541 llvm_unreachable("unknown evaluating decl kind");
3542 }
3543
3544 namespace {
3545 /// A handle to a complete object (an object that is not a subobject of
3546 /// another object).
3547 struct CompleteObject {
3548 /// The identity of the object.
3549 APValue::LValueBase Base;
3550 /// The value of the complete object.
3551 APValue *Value;
3552 /// The type of the complete object.
3553 QualType Type;
3554
CompleteObject__anon4a4db2530911::CompleteObject3555 CompleteObject() : Value(nullptr) {}
CompleteObject__anon4a4db2530911::CompleteObject3556 CompleteObject(APValue::LValueBase Base, APValue *Value, QualType Type)
3557 : Base(Base), Value(Value), Type(Type) {}
3558
mayAccessMutableMembers__anon4a4db2530911::CompleteObject3559 bool mayAccessMutableMembers(EvalInfo &Info, AccessKinds AK) const {
3560 // If this isn't a "real" access (eg, if it's just accessing the type
3561 // info), allow it. We assume the type doesn't change dynamically for
3562 // subobjects of constexpr objects (even though we'd hit UB here if it
3563 // did). FIXME: Is this right?
3564 if (!isAnyAccess(AK))
3565 return true;
3566
3567 // In C++14 onwards, it is permitted to read a mutable member whose
3568 // lifetime began within the evaluation.
3569 // FIXME: Should we also allow this in C++11?
3570 if (!Info.getLangOpts().CPlusPlus14)
3571 return false;
3572 return lifetimeStartedInEvaluation(Info, Base, /*MutableSubobject*/true);
3573 }
3574
operator bool__anon4a4db2530911::CompleteObject3575 explicit operator bool() const { return !Type.isNull(); }
3576 };
3577 } // end anonymous namespace
3578
getSubobjectType(QualType ObjType,QualType SubobjType,bool IsMutable=false)3579 static QualType getSubobjectType(QualType ObjType, QualType SubobjType,
3580 bool IsMutable = false) {
3581 // C++ [basic.type.qualifier]p1:
3582 // - A const object is an object of type const T or a non-mutable subobject
3583 // of a const object.
3584 if (ObjType.isConstQualified() && !IsMutable)
3585 SubobjType.addConst();
3586 // - A volatile object is an object of type const T or a subobject of a
3587 // volatile object.
3588 if (ObjType.isVolatileQualified())
3589 SubobjType.addVolatile();
3590 return SubobjType;
3591 }
3592
3593 /// Find the designated sub-object of an rvalue.
3594 template<typename SubobjectHandler>
3595 typename SubobjectHandler::result_type
findSubobject(EvalInfo & Info,const Expr * E,const CompleteObject & Obj,const SubobjectDesignator & Sub,SubobjectHandler & handler)3596 findSubobject(EvalInfo &Info, const Expr *E, const CompleteObject &Obj,
3597 const SubobjectDesignator &Sub, SubobjectHandler &handler) {
3598 if (Sub.Invalid)
3599 // A diagnostic will have already been produced.
3600 return handler.failed();
3601 if (Sub.isOnePastTheEnd() || Sub.isMostDerivedAnUnsizedArray()) {
3602 if (Info.getLangOpts().CPlusPlus11)
3603 Info.FFDiag(E, Sub.isOnePastTheEnd()
3604 ? diag::note_constexpr_access_past_end
3605 : diag::note_constexpr_access_unsized_array)
3606 << handler.AccessKind;
3607 else
3608 Info.FFDiag(E);
3609 return handler.failed();
3610 }
3611
3612 APValue *O = Obj.Value;
3613 QualType ObjType = Obj.Type;
3614 const FieldDecl *LastField = nullptr;
3615 const FieldDecl *VolatileField = nullptr;
3616
3617 // Walk the designator's path to find the subobject.
3618 for (unsigned I = 0, N = Sub.Entries.size(); /**/; ++I) {
3619 // Reading an indeterminate value is undefined, but assigning over one is OK.
3620 if ((O->isAbsent() && !(handler.AccessKind == AK_Construct && I == N)) ||
3621 (O->isIndeterminate() &&
3622 !isValidIndeterminateAccess(handler.AccessKind))) {
3623 if (!Info.checkingPotentialConstantExpression())
3624 Info.FFDiag(E, diag::note_constexpr_access_uninit)
3625 << handler.AccessKind << O->isIndeterminate();
3626 return handler.failed();
3627 }
3628
3629 // C++ [class.ctor]p5, C++ [class.dtor]p5:
3630 // const and volatile semantics are not applied on an object under
3631 // {con,de}struction.
3632 if ((ObjType.isConstQualified() || ObjType.isVolatileQualified()) &&
3633 ObjType->isRecordType() &&
3634 Info.isEvaluatingCtorDtor(
3635 Obj.Base, llvm::makeArrayRef(Sub.Entries.begin(),
3636 Sub.Entries.begin() + I)) !=
3637 ConstructionPhase::None) {
3638 ObjType = Info.Ctx.getCanonicalType(ObjType);
3639 ObjType.removeLocalConst();
3640 ObjType.removeLocalVolatile();
3641 }
3642
3643 // If this is our last pass, check that the final object type is OK.
3644 if (I == N || (I == N - 1 && ObjType->isAnyComplexType())) {
3645 // Accesses to volatile objects are prohibited.
3646 if (ObjType.isVolatileQualified() && isFormalAccess(handler.AccessKind)) {
3647 if (Info.getLangOpts().CPlusPlus) {
3648 int DiagKind;
3649 SourceLocation Loc;
3650 const NamedDecl *Decl = nullptr;
3651 if (VolatileField) {
3652 DiagKind = 2;
3653 Loc = VolatileField->getLocation();
3654 Decl = VolatileField;
3655 } else if (auto *VD = Obj.Base.dyn_cast<const ValueDecl*>()) {
3656 DiagKind = 1;
3657 Loc = VD->getLocation();
3658 Decl = VD;
3659 } else {
3660 DiagKind = 0;
3661 if (auto *E = Obj.Base.dyn_cast<const Expr *>())
3662 Loc = E->getExprLoc();
3663 }
3664 Info.FFDiag(E, diag::note_constexpr_access_volatile_obj, 1)
3665 << handler.AccessKind << DiagKind << Decl;
3666 Info.Note(Loc, diag::note_constexpr_volatile_here) << DiagKind;
3667 } else {
3668 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
3669 }
3670 return handler.failed();
3671 }
3672
3673 // If we are reading an object of class type, there may still be more
3674 // things we need to check: if there are any mutable subobjects, we
3675 // cannot perform this read. (This only happens when performing a trivial
3676 // copy or assignment.)
3677 if (ObjType->isRecordType() &&
3678 !Obj.mayAccessMutableMembers(Info, handler.AccessKind) &&
3679 diagnoseMutableFields(Info, E, handler.AccessKind, ObjType))
3680 return handler.failed();
3681 }
3682
3683 if (I == N) {
3684 if (!handler.found(*O, ObjType))
3685 return false;
3686
3687 // If we modified a bit-field, truncate it to the right width.
3688 if (isModification(handler.AccessKind) &&
3689 LastField && LastField->isBitField() &&
3690 !truncateBitfieldValue(Info, E, *O, LastField))
3691 return false;
3692
3693 return true;
3694 }
3695
3696 LastField = nullptr;
3697 if (ObjType->isArrayType()) {
3698 // Next subobject is an array element.
3699 const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(ObjType);
3700 assert(CAT && "vla in literal type?");
3701 uint64_t Index = Sub.Entries[I].getAsArrayIndex();
3702 if (CAT->getSize().ule(Index)) {
3703 // Note, it should not be possible to form a pointer with a valid
3704 // designator which points more than one past the end of the array.
3705 if (Info.getLangOpts().CPlusPlus11)
3706 Info.FFDiag(E, diag::note_constexpr_access_past_end)
3707 << handler.AccessKind;
3708 else
3709 Info.FFDiag(E);
3710 return handler.failed();
3711 }
3712
3713 ObjType = CAT->getElementType();
3714
3715 if (O->getArrayInitializedElts() > Index)
3716 O = &O->getArrayInitializedElt(Index);
3717 else if (!isRead(handler.AccessKind)) {
3718 expandArray(*O, Index);
3719 O = &O->getArrayInitializedElt(Index);
3720 } else
3721 O = &O->getArrayFiller();
3722 } else if (ObjType->isAnyComplexType()) {
3723 // Next subobject is a complex number.
3724 uint64_t Index = Sub.Entries[I].getAsArrayIndex();
3725 if (Index > 1) {
3726 if (Info.getLangOpts().CPlusPlus11)
3727 Info.FFDiag(E, diag::note_constexpr_access_past_end)
3728 << handler.AccessKind;
3729 else
3730 Info.FFDiag(E);
3731 return handler.failed();
3732 }
3733
3734 ObjType = getSubobjectType(
3735 ObjType, ObjType->castAs<ComplexType>()->getElementType());
3736
3737 assert(I == N - 1 && "extracting subobject of scalar?");
3738 if (O->isComplexInt()) {
3739 return handler.found(Index ? O->getComplexIntImag()
3740 : O->getComplexIntReal(), ObjType);
3741 } else {
3742 assert(O->isComplexFloat());
3743 return handler.found(Index ? O->getComplexFloatImag()
3744 : O->getComplexFloatReal(), ObjType);
3745 }
3746 } else if (const FieldDecl *Field = getAsField(Sub.Entries[I])) {
3747 if (Field->isMutable() &&
3748 !Obj.mayAccessMutableMembers(Info, handler.AccessKind)) {
3749 Info.FFDiag(E, diag::note_constexpr_access_mutable, 1)
3750 << handler.AccessKind << Field;
3751 Info.Note(Field->getLocation(), diag::note_declared_at);
3752 return handler.failed();
3753 }
3754
3755 // Next subobject is a class, struct or union field.
3756 RecordDecl *RD = ObjType->castAs<RecordType>()->getDecl();
3757 if (RD->isUnion()) {
3758 const FieldDecl *UnionField = O->getUnionField();
3759 if (!UnionField ||
3760 UnionField->getCanonicalDecl() != Field->getCanonicalDecl()) {
3761 if (I == N - 1 && handler.AccessKind == AK_Construct) {
3762 // Placement new onto an inactive union member makes it active.
3763 O->setUnion(Field, APValue());
3764 } else {
3765 // FIXME: If O->getUnionValue() is absent, report that there's no
3766 // active union member rather than reporting the prior active union
3767 // member. We'll need to fix nullptr_t to not use APValue() as its
3768 // representation first.
3769 Info.FFDiag(E, diag::note_constexpr_access_inactive_union_member)
3770 << handler.AccessKind << Field << !UnionField << UnionField;
3771 return handler.failed();
3772 }
3773 }
3774 O = &O->getUnionValue();
3775 } else
3776 O = &O->getStructField(Field->getFieldIndex());
3777
3778 ObjType = getSubobjectType(ObjType, Field->getType(), Field->isMutable());
3779 LastField = Field;
3780 if (Field->getType().isVolatileQualified())
3781 VolatileField = Field;
3782 } else {
3783 // Next subobject is a base class.
3784 const CXXRecordDecl *Derived = ObjType->getAsCXXRecordDecl();
3785 const CXXRecordDecl *Base = getAsBaseClass(Sub.Entries[I]);
3786 O = &O->getStructBase(getBaseIndex(Derived, Base));
3787
3788 ObjType = getSubobjectType(ObjType, Info.Ctx.getRecordType(Base));
3789 }
3790 }
3791 }
3792
3793 namespace {
3794 struct ExtractSubobjectHandler {
3795 EvalInfo &Info;
3796 const Expr *E;
3797 APValue &Result;
3798 const AccessKinds AccessKind;
3799
3800 typedef bool result_type;
failed__anon4a4db2530a11::ExtractSubobjectHandler3801 bool failed() { return false; }
found__anon4a4db2530a11::ExtractSubobjectHandler3802 bool found(APValue &Subobj, QualType SubobjType) {
3803 Result = Subobj;
3804 if (AccessKind == AK_ReadObjectRepresentation)
3805 return true;
3806 return CheckFullyInitialized(Info, E->getExprLoc(), SubobjType, Result);
3807 }
found__anon4a4db2530a11::ExtractSubobjectHandler3808 bool found(APSInt &Value, QualType SubobjType) {
3809 Result = APValue(Value);
3810 return true;
3811 }
found__anon4a4db2530a11::ExtractSubobjectHandler3812 bool found(APFloat &Value, QualType SubobjType) {
3813 Result = APValue(Value);
3814 return true;
3815 }
3816 };
3817 } // end anonymous namespace
3818
3819 /// 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)3820 static bool extractSubobject(EvalInfo &Info, const Expr *E,
3821 const CompleteObject &Obj,
3822 const SubobjectDesignator &Sub, APValue &Result,
3823 AccessKinds AK = AK_Read) {
3824 assert(AK == AK_Read || AK == AK_ReadObjectRepresentation);
3825 ExtractSubobjectHandler Handler = {Info, E, Result, AK};
3826 return findSubobject(Info, E, Obj, Sub, Handler);
3827 }
3828
3829 namespace {
3830 struct ModifySubobjectHandler {
3831 EvalInfo &Info;
3832 APValue &NewVal;
3833 const Expr *E;
3834
3835 typedef bool result_type;
3836 static const AccessKinds AccessKind = AK_Assign;
3837
checkConst__anon4a4db2530b11::ModifySubobjectHandler3838 bool checkConst(QualType QT) {
3839 // Assigning to a const object has undefined behavior.
3840 if (QT.isConstQualified()) {
3841 Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT;
3842 return false;
3843 }
3844 return true;
3845 }
3846
failed__anon4a4db2530b11::ModifySubobjectHandler3847 bool failed() { return false; }
found__anon4a4db2530b11::ModifySubobjectHandler3848 bool found(APValue &Subobj, QualType SubobjType) {
3849 if (!checkConst(SubobjType))
3850 return false;
3851 // We've been given ownership of NewVal, so just swap it in.
3852 Subobj.swap(NewVal);
3853 return true;
3854 }
found__anon4a4db2530b11::ModifySubobjectHandler3855 bool found(APSInt &Value, QualType SubobjType) {
3856 if (!checkConst(SubobjType))
3857 return false;
3858 if (!NewVal.isInt()) {
3859 // Maybe trying to write a cast pointer value into a complex?
3860 Info.FFDiag(E);
3861 return false;
3862 }
3863 Value = NewVal.getInt();
3864 return true;
3865 }
found__anon4a4db2530b11::ModifySubobjectHandler3866 bool found(APFloat &Value, QualType SubobjType) {
3867 if (!checkConst(SubobjType))
3868 return false;
3869 Value = NewVal.getFloat();
3870 return true;
3871 }
3872 };
3873 } // end anonymous namespace
3874
3875 const AccessKinds ModifySubobjectHandler::AccessKind;
3876
3877 /// 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)3878 static bool modifySubobject(EvalInfo &Info, const Expr *E,
3879 const CompleteObject &Obj,
3880 const SubobjectDesignator &Sub,
3881 APValue &NewVal) {
3882 ModifySubobjectHandler Handler = { Info, NewVal, E };
3883 return findSubobject(Info, E, Obj, Sub, Handler);
3884 }
3885
3886 /// Find the position where two subobject designators diverge, or equivalently
3887 /// the length of the common initial subsequence.
FindDesignatorMismatch(QualType ObjType,const SubobjectDesignator & A,const SubobjectDesignator & B,bool & WasArrayIndex)3888 static unsigned FindDesignatorMismatch(QualType ObjType,
3889 const SubobjectDesignator &A,
3890 const SubobjectDesignator &B,
3891 bool &WasArrayIndex) {
3892 unsigned I = 0, N = std::min(A.Entries.size(), B.Entries.size());
3893 for (/**/; I != N; ++I) {
3894 if (!ObjType.isNull() &&
3895 (ObjType->isArrayType() || ObjType->isAnyComplexType())) {
3896 // Next subobject is an array element.
3897 if (A.Entries[I].getAsArrayIndex() != B.Entries[I].getAsArrayIndex()) {
3898 WasArrayIndex = true;
3899 return I;
3900 }
3901 if (ObjType->isAnyComplexType())
3902 ObjType = ObjType->castAs<ComplexType>()->getElementType();
3903 else
3904 ObjType = ObjType->castAsArrayTypeUnsafe()->getElementType();
3905 } else {
3906 if (A.Entries[I].getAsBaseOrMember() !=
3907 B.Entries[I].getAsBaseOrMember()) {
3908 WasArrayIndex = false;
3909 return I;
3910 }
3911 if (const FieldDecl *FD = getAsField(A.Entries[I]))
3912 // Next subobject is a field.
3913 ObjType = FD->getType();
3914 else
3915 // Next subobject is a base class.
3916 ObjType = QualType();
3917 }
3918 }
3919 WasArrayIndex = false;
3920 return I;
3921 }
3922
3923 /// Determine whether the given subobject designators refer to elements of the
3924 /// same array object.
AreElementsOfSameArray(QualType ObjType,const SubobjectDesignator & A,const SubobjectDesignator & B)3925 static bool AreElementsOfSameArray(QualType ObjType,
3926 const SubobjectDesignator &A,
3927 const SubobjectDesignator &B) {
3928 if (A.Entries.size() != B.Entries.size())
3929 return false;
3930
3931 bool IsArray = A.MostDerivedIsArrayElement;
3932 if (IsArray && A.MostDerivedPathLength != A.Entries.size())
3933 // A is a subobject of the array element.
3934 return false;
3935
3936 // If A (and B) designates an array element, the last entry will be the array
3937 // index. That doesn't have to match. Otherwise, we're in the 'implicit array
3938 // of length 1' case, and the entire path must match.
3939 bool WasArrayIndex;
3940 unsigned CommonLength = FindDesignatorMismatch(ObjType, A, B, WasArrayIndex);
3941 return CommonLength >= A.Entries.size() - IsArray;
3942 }
3943
3944 /// Find the complete object to which an LValue refers.
findCompleteObject(EvalInfo & Info,const Expr * E,AccessKinds AK,const LValue & LVal,QualType LValType)3945 static CompleteObject findCompleteObject(EvalInfo &Info, const Expr *E,
3946 AccessKinds AK, const LValue &LVal,
3947 QualType LValType) {
3948 if (LVal.InvalidBase) {
3949 Info.FFDiag(E);
3950 return CompleteObject();
3951 }
3952
3953 if (!LVal.Base) {
3954 Info.FFDiag(E, diag::note_constexpr_access_null) << AK;
3955 return CompleteObject();
3956 }
3957
3958 CallStackFrame *Frame = nullptr;
3959 unsigned Depth = 0;
3960 if (LVal.getLValueCallIndex()) {
3961 std::tie(Frame, Depth) =
3962 Info.getCallFrameAndDepth(LVal.getLValueCallIndex());
3963 if (!Frame) {
3964 Info.FFDiag(E, diag::note_constexpr_lifetime_ended, 1)
3965 << AK << LVal.Base.is<const ValueDecl*>();
3966 NoteLValueLocation(Info, LVal.Base);
3967 return CompleteObject();
3968 }
3969 }
3970
3971 bool IsAccess = isAnyAccess(AK);
3972
3973 // C++11 DR1311: An lvalue-to-rvalue conversion on a volatile-qualified type
3974 // is not a constant expression (even if the object is non-volatile). We also
3975 // apply this rule to C++98, in order to conform to the expected 'volatile'
3976 // semantics.
3977 if (isFormalAccess(AK) && LValType.isVolatileQualified()) {
3978 if (Info.getLangOpts().CPlusPlus)
3979 Info.FFDiag(E, diag::note_constexpr_access_volatile_type)
3980 << AK << LValType;
3981 else
3982 Info.FFDiag(E);
3983 return CompleteObject();
3984 }
3985
3986 // Compute value storage location and type of base object.
3987 APValue *BaseVal = nullptr;
3988 QualType BaseType = getType(LVal.Base);
3989
3990 if (Info.getLangOpts().CPlusPlus14 && LVal.Base == Info.EvaluatingDecl &&
3991 lifetimeStartedInEvaluation(Info, LVal.Base)) {
3992 // This is the object whose initializer we're evaluating, so its lifetime
3993 // started in the current evaluation.
3994 BaseVal = Info.EvaluatingDeclValue;
3995 } else if (const ValueDecl *D = LVal.Base.dyn_cast<const ValueDecl *>()) {
3996 // Allow reading from a GUID declaration.
3997 if (auto *GD = dyn_cast<MSGuidDecl>(D)) {
3998 if (isModification(AK)) {
3999 // All the remaining cases do not permit modification of the object.
4000 Info.FFDiag(E, diag::note_constexpr_modify_global);
4001 return CompleteObject();
4002 }
4003 APValue &V = GD->getAsAPValue();
4004 if (V.isAbsent()) {
4005 Info.FFDiag(E, diag::note_constexpr_unsupported_layout)
4006 << GD->getType();
4007 return CompleteObject();
4008 }
4009 return CompleteObject(LVal.Base, &V, GD->getType());
4010 }
4011
4012 // Allow reading from template parameter objects.
4013 if (auto *TPO = dyn_cast<TemplateParamObjectDecl>(D)) {
4014 if (isModification(AK)) {
4015 Info.FFDiag(E, diag::note_constexpr_modify_global);
4016 return CompleteObject();
4017 }
4018 return CompleteObject(LVal.Base, const_cast<APValue *>(&TPO->getValue()),
4019 TPO->getType());
4020 }
4021
4022 // In C++98, const, non-volatile integers initialized with ICEs are ICEs.
4023 // In C++11, constexpr, non-volatile variables initialized with constant
4024 // expressions are constant expressions too. Inside constexpr functions,
4025 // parameters are constant expressions even if they're non-const.
4026 // In C++1y, objects local to a constant expression (those with a Frame) are
4027 // both readable and writable inside constant expressions.
4028 // In C, such things can also be folded, although they are not ICEs.
4029 const VarDecl *VD = dyn_cast<VarDecl>(D);
4030 if (VD) {
4031 if (const VarDecl *VDef = VD->getDefinition(Info.Ctx))
4032 VD = VDef;
4033 }
4034 if (!VD || VD->isInvalidDecl()) {
4035 Info.FFDiag(E);
4036 return CompleteObject();
4037 }
4038
4039 bool IsConstant = BaseType.isConstant(Info.Ctx);
4040
4041 // Unless we're looking at a local variable or argument in a constexpr call,
4042 // the variable we're reading must be const.
4043 if (!Frame) {
4044 if (IsAccess && isa<ParmVarDecl>(VD)) {
4045 // Access of a parameter that's not associated with a frame isn't going
4046 // to work out, but we can leave it to evaluateVarDeclInit to provide a
4047 // suitable diagnostic.
4048 } else if (Info.getLangOpts().CPlusPlus14 &&
4049 lifetimeStartedInEvaluation(Info, LVal.Base)) {
4050 // OK, we can read and modify an object if we're in the process of
4051 // evaluating its initializer, because its lifetime began in this
4052 // evaluation.
4053 } else if (isModification(AK)) {
4054 // All the remaining cases do not permit modification of the object.
4055 Info.FFDiag(E, diag::note_constexpr_modify_global);
4056 return CompleteObject();
4057 } else if (VD->isConstexpr()) {
4058 // OK, we can read this variable.
4059 } else if (BaseType->isIntegralOrEnumerationType()) {
4060 if (!IsConstant) {
4061 if (!IsAccess)
4062 return CompleteObject(LVal.getLValueBase(), nullptr, BaseType);
4063 if (Info.getLangOpts().CPlusPlus) {
4064 Info.FFDiag(E, diag::note_constexpr_ltor_non_const_int, 1) << VD;
4065 Info.Note(VD->getLocation(), diag::note_declared_at);
4066 } else {
4067 Info.FFDiag(E);
4068 }
4069 return CompleteObject();
4070 }
4071 } else if (!IsAccess) {
4072 return CompleteObject(LVal.getLValueBase(), nullptr, BaseType);
4073 } else if (IsConstant && Info.checkingPotentialConstantExpression() &&
4074 BaseType->isLiteralType(Info.Ctx) && !VD->hasDefinition()) {
4075 // This variable might end up being constexpr. Don't diagnose it yet.
4076 } else if (IsConstant) {
4077 // Keep evaluating to see what we can do. In particular, we support
4078 // folding of const floating-point types, in order to make static const
4079 // data members of such types (supported as an extension) more useful.
4080 if (Info.getLangOpts().CPlusPlus) {
4081 Info.CCEDiag(E, Info.getLangOpts().CPlusPlus11
4082 ? diag::note_constexpr_ltor_non_constexpr
4083 : diag::note_constexpr_ltor_non_integral, 1)
4084 << VD << BaseType;
4085 Info.Note(VD->getLocation(), diag::note_declared_at);
4086 } else {
4087 Info.CCEDiag(E);
4088 }
4089 } else {
4090 // Never allow reading a non-const value.
4091 if (Info.getLangOpts().CPlusPlus) {
4092 Info.FFDiag(E, Info.getLangOpts().CPlusPlus11
4093 ? diag::note_constexpr_ltor_non_constexpr
4094 : diag::note_constexpr_ltor_non_integral, 1)
4095 << VD << BaseType;
4096 Info.Note(VD->getLocation(), diag::note_declared_at);
4097 } else {
4098 Info.FFDiag(E);
4099 }
4100 return CompleteObject();
4101 }
4102 }
4103
4104 if (!evaluateVarDeclInit(Info, E, VD, Frame, LVal.getLValueVersion(), BaseVal))
4105 return CompleteObject();
4106 } else if (DynamicAllocLValue DA = LVal.Base.dyn_cast<DynamicAllocLValue>()) {
4107 Optional<DynAlloc*> Alloc = Info.lookupDynamicAlloc(DA);
4108 if (!Alloc) {
4109 Info.FFDiag(E, diag::note_constexpr_access_deleted_object) << AK;
4110 return CompleteObject();
4111 }
4112 return CompleteObject(LVal.Base, &(*Alloc)->Value,
4113 LVal.Base.getDynamicAllocType());
4114 } else {
4115 const Expr *Base = LVal.Base.dyn_cast<const Expr*>();
4116
4117 if (!Frame) {
4118 if (const MaterializeTemporaryExpr *MTE =
4119 dyn_cast_or_null<MaterializeTemporaryExpr>(Base)) {
4120 assert(MTE->getStorageDuration() == SD_Static &&
4121 "should have a frame for a non-global materialized temporary");
4122
4123 // C++20 [expr.const]p4: [DR2126]
4124 // An object or reference is usable in constant expressions if it is
4125 // - a temporary object of non-volatile const-qualified literal type
4126 // whose lifetime is extended to that of a variable that is usable
4127 // in constant expressions
4128 //
4129 // C++20 [expr.const]p5:
4130 // an lvalue-to-rvalue conversion [is not allowed unless it applies to]
4131 // - a non-volatile glvalue that refers to an object that is usable
4132 // in constant expressions, or
4133 // - a non-volatile glvalue of literal type that refers to a
4134 // non-volatile object whose lifetime began within the evaluation
4135 // of E;
4136 //
4137 // C++11 misses the 'began within the evaluation of e' check and
4138 // instead allows all temporaries, including things like:
4139 // int &&r = 1;
4140 // int x = ++r;
4141 // constexpr int k = r;
4142 // Therefore we use the C++14-onwards rules in C++11 too.
4143 //
4144 // Note that temporaries whose lifetimes began while evaluating a
4145 // variable's constructor are not usable while evaluating the
4146 // corresponding destructor, not even if they're of const-qualified
4147 // types.
4148 if (!MTE->isUsableInConstantExpressions(Info.Ctx) &&
4149 !lifetimeStartedInEvaluation(Info, LVal.Base)) {
4150 if (!IsAccess)
4151 return CompleteObject(LVal.getLValueBase(), nullptr, BaseType);
4152 Info.FFDiag(E, diag::note_constexpr_access_static_temporary, 1) << AK;
4153 Info.Note(MTE->getExprLoc(), diag::note_constexpr_temporary_here);
4154 return CompleteObject();
4155 }
4156
4157 BaseVal = MTE->getOrCreateValue(false);
4158 assert(BaseVal && "got reference to unevaluated temporary");
4159 } else {
4160 if (!IsAccess)
4161 return CompleteObject(LVal.getLValueBase(), nullptr, BaseType);
4162 APValue Val;
4163 LVal.moveInto(Val);
4164 Info.FFDiag(E, diag::note_constexpr_access_unreadable_object)
4165 << AK
4166 << Val.getAsString(Info.Ctx,
4167 Info.Ctx.getLValueReferenceType(LValType));
4168 NoteLValueLocation(Info, LVal.Base);
4169 return CompleteObject();
4170 }
4171 } else {
4172 BaseVal = Frame->getTemporary(Base, LVal.Base.getVersion());
4173 assert(BaseVal && "missing value for temporary");
4174 }
4175 }
4176
4177 // In C++14, we can't safely access any mutable state when we might be
4178 // evaluating after an unmodeled side effect. Parameters are modeled as state
4179 // in the caller, but aren't visible once the call returns, so they can be
4180 // modified in a speculatively-evaluated call.
4181 //
4182 // FIXME: Not all local state is mutable. Allow local constant subobjects
4183 // to be read here (but take care with 'mutable' fields).
4184 unsigned VisibleDepth = Depth;
4185 if (llvm::isa_and_nonnull<ParmVarDecl>(
4186 LVal.Base.dyn_cast<const ValueDecl *>()))
4187 ++VisibleDepth;
4188 if ((Frame && Info.getLangOpts().CPlusPlus14 &&
4189 Info.EvalStatus.HasSideEffects) ||
4190 (isModification(AK) && VisibleDepth < Info.SpeculativeEvaluationDepth))
4191 return CompleteObject();
4192
4193 return CompleteObject(LVal.getLValueBase(), BaseVal, BaseType);
4194 }
4195
4196 /// Perform an lvalue-to-rvalue conversion on the given glvalue. This
4197 /// can also be used for 'lvalue-to-lvalue' conversions for looking up the
4198 /// glvalue referred to by an entity of reference type.
4199 ///
4200 /// \param Info - Information about the ongoing evaluation.
4201 /// \param Conv - The expression for which we are performing the conversion.
4202 /// Used for diagnostics.
4203 /// \param Type - The type of the glvalue (before stripping cv-qualifiers in the
4204 /// case of a non-class type).
4205 /// \param LVal - The glvalue on which we are attempting to perform this action.
4206 /// \param RVal - The produced value will be placed here.
4207 /// \param WantObjectRepresentation - If true, we're looking for the object
4208 /// representation rather than the value, and in particular,
4209 /// there is no requirement that the result be fully initialized.
4210 static bool
handleLValueToRValueConversion(EvalInfo & Info,const Expr * Conv,QualType Type,const LValue & LVal,APValue & RVal,bool WantObjectRepresentation=false)4211 handleLValueToRValueConversion(EvalInfo &Info, const Expr *Conv, QualType Type,
4212 const LValue &LVal, APValue &RVal,
4213 bool WantObjectRepresentation = false) {
4214 if (LVal.Designator.Invalid)
4215 return false;
4216
4217 // Check for special cases where there is no existing APValue to look at.
4218 const Expr *Base = LVal.Base.dyn_cast<const Expr*>();
4219
4220 AccessKinds AK =
4221 WantObjectRepresentation ? AK_ReadObjectRepresentation : AK_Read;
4222
4223 if (Base && !LVal.getLValueCallIndex() && !Type.isVolatileQualified()) {
4224 if (const CompoundLiteralExpr *CLE = dyn_cast<CompoundLiteralExpr>(Base)) {
4225 // In C99, a CompoundLiteralExpr is an lvalue, and we defer evaluating the
4226 // initializer until now for such expressions. Such an expression can't be
4227 // an ICE in C, so this only matters for fold.
4228 if (Type.isVolatileQualified()) {
4229 Info.FFDiag(Conv);
4230 return false;
4231 }
4232 APValue Lit;
4233 if (!Evaluate(Lit, Info, CLE->getInitializer()))
4234 return false;
4235 CompleteObject LitObj(LVal.Base, &Lit, Base->getType());
4236 return extractSubobject(Info, Conv, LitObj, LVal.Designator, RVal, AK);
4237 } else if (isa<StringLiteral>(Base) || isa<PredefinedExpr>(Base)) {
4238 // Special-case character extraction so we don't have to construct an
4239 // APValue for the whole string.
4240 assert(LVal.Designator.Entries.size() <= 1 &&
4241 "Can only read characters from string literals");
4242 if (LVal.Designator.Entries.empty()) {
4243 // Fail for now for LValue to RValue conversion of an array.
4244 // (This shouldn't show up in C/C++, but it could be triggered by a
4245 // weird EvaluateAsRValue call from a tool.)
4246 Info.FFDiag(Conv);
4247 return false;
4248 }
4249 if (LVal.Designator.isOnePastTheEnd()) {
4250 if (Info.getLangOpts().CPlusPlus11)
4251 Info.FFDiag(Conv, diag::note_constexpr_access_past_end) << AK;
4252 else
4253 Info.FFDiag(Conv);
4254 return false;
4255 }
4256 uint64_t CharIndex = LVal.Designator.Entries[0].getAsArrayIndex();
4257 RVal = APValue(extractStringLiteralCharacter(Info, Base, CharIndex));
4258 return true;
4259 }
4260 }
4261
4262 CompleteObject Obj = findCompleteObject(Info, Conv, AK, LVal, Type);
4263 return Obj && extractSubobject(Info, Conv, Obj, LVal.Designator, RVal, AK);
4264 }
4265
4266 /// Perform an assignment of Val to LVal. Takes ownership of Val.
handleAssignment(EvalInfo & Info,const Expr * E,const LValue & LVal,QualType LValType,APValue & Val)4267 static bool handleAssignment(EvalInfo &Info, const Expr *E, const LValue &LVal,
4268 QualType LValType, APValue &Val) {
4269 if (LVal.Designator.Invalid)
4270 return false;
4271
4272 if (!Info.getLangOpts().CPlusPlus14) {
4273 Info.FFDiag(E);
4274 return false;
4275 }
4276
4277 CompleteObject Obj = findCompleteObject(Info, E, AK_Assign, LVal, LValType);
4278 return Obj && modifySubobject(Info, E, Obj, LVal.Designator, Val);
4279 }
4280
4281 namespace {
4282 struct CompoundAssignSubobjectHandler {
4283 EvalInfo &Info;
4284 const CompoundAssignOperator *E;
4285 QualType PromotedLHSType;
4286 BinaryOperatorKind Opcode;
4287 const APValue &RHS;
4288
4289 static const AccessKinds AccessKind = AK_Assign;
4290
4291 typedef bool result_type;
4292
checkConst__anon4a4db2530c11::CompoundAssignSubobjectHandler4293 bool checkConst(QualType QT) {
4294 // Assigning to a const object has undefined behavior.
4295 if (QT.isConstQualified()) {
4296 Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT;
4297 return false;
4298 }
4299 return true;
4300 }
4301
failed__anon4a4db2530c11::CompoundAssignSubobjectHandler4302 bool failed() { return false; }
found__anon4a4db2530c11::CompoundAssignSubobjectHandler4303 bool found(APValue &Subobj, QualType SubobjType) {
4304 switch (Subobj.getKind()) {
4305 case APValue::Int:
4306 return found(Subobj.getInt(), SubobjType);
4307 case APValue::Float:
4308 return found(Subobj.getFloat(), SubobjType);
4309 case APValue::ComplexInt:
4310 case APValue::ComplexFloat:
4311 // FIXME: Implement complex compound assignment.
4312 Info.FFDiag(E);
4313 return false;
4314 case APValue::LValue:
4315 return foundPointer(Subobj, SubobjType);
4316 case APValue::Vector:
4317 return foundVector(Subobj, SubobjType);
4318 default:
4319 // FIXME: can this happen?
4320 Info.FFDiag(E);
4321 return false;
4322 }
4323 }
4324
foundVector__anon4a4db2530c11::CompoundAssignSubobjectHandler4325 bool foundVector(APValue &Value, QualType SubobjType) {
4326 if (!checkConst(SubobjType))
4327 return false;
4328
4329 if (!SubobjType->isVectorType()) {
4330 Info.FFDiag(E);
4331 return false;
4332 }
4333 return handleVectorVectorBinOp(Info, E, Opcode, Value, RHS);
4334 }
4335
found__anon4a4db2530c11::CompoundAssignSubobjectHandler4336 bool found(APSInt &Value, QualType SubobjType) {
4337 if (!checkConst(SubobjType))
4338 return false;
4339
4340 if (!SubobjType->isIntegerType()) {
4341 // We don't support compound assignment on integer-cast-to-pointer
4342 // values.
4343 Info.FFDiag(E);
4344 return false;
4345 }
4346
4347 if (RHS.isInt()) {
4348 APSInt LHS =
4349 HandleIntToIntCast(Info, E, PromotedLHSType, SubobjType, Value);
4350 if (!handleIntIntBinOp(Info, E, LHS, Opcode, RHS.getInt(), LHS))
4351 return false;
4352 Value = HandleIntToIntCast(Info, E, SubobjType, PromotedLHSType, LHS);
4353 return true;
4354 } else if (RHS.isFloat()) {
4355 const FPOptions FPO = E->getFPFeaturesInEffect(
4356 Info.Ctx.getLangOpts());
4357 APFloat FValue(0.0);
4358 return HandleIntToFloatCast(Info, E, FPO, SubobjType, Value,
4359 PromotedLHSType, FValue) &&
4360 handleFloatFloatBinOp(Info, E, FValue, Opcode, RHS.getFloat()) &&
4361 HandleFloatToIntCast(Info, E, PromotedLHSType, FValue, SubobjType,
4362 Value);
4363 }
4364
4365 Info.FFDiag(E);
4366 return false;
4367 }
found__anon4a4db2530c11::CompoundAssignSubobjectHandler4368 bool found(APFloat &Value, QualType SubobjType) {
4369 return checkConst(SubobjType) &&
4370 HandleFloatToFloatCast(Info, E, SubobjType, PromotedLHSType,
4371 Value) &&
4372 handleFloatFloatBinOp(Info, E, Value, Opcode, RHS.getFloat()) &&
4373 HandleFloatToFloatCast(Info, E, PromotedLHSType, SubobjType, Value);
4374 }
foundPointer__anon4a4db2530c11::CompoundAssignSubobjectHandler4375 bool foundPointer(APValue &Subobj, QualType SubobjType) {
4376 if (!checkConst(SubobjType))
4377 return false;
4378
4379 QualType PointeeType;
4380 if (const PointerType *PT = SubobjType->getAs<PointerType>())
4381 PointeeType = PT->getPointeeType();
4382
4383 if (PointeeType.isNull() || !RHS.isInt() ||
4384 (Opcode != BO_Add && Opcode != BO_Sub)) {
4385 Info.FFDiag(E);
4386 return false;
4387 }
4388
4389 APSInt Offset = RHS.getInt();
4390 if (Opcode == BO_Sub)
4391 negateAsSigned(Offset);
4392
4393 LValue LVal;
4394 LVal.setFrom(Info.Ctx, Subobj);
4395 if (!HandleLValueArrayAdjustment(Info, E, LVal, PointeeType, Offset))
4396 return false;
4397 LVal.moveInto(Subobj);
4398 return true;
4399 }
4400 };
4401 } // end anonymous namespace
4402
4403 const AccessKinds CompoundAssignSubobjectHandler::AccessKind;
4404
4405 /// 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)4406 static bool handleCompoundAssignment(EvalInfo &Info,
4407 const CompoundAssignOperator *E,
4408 const LValue &LVal, QualType LValType,
4409 QualType PromotedLValType,
4410 BinaryOperatorKind Opcode,
4411 const APValue &RVal) {
4412 if (LVal.Designator.Invalid)
4413 return false;
4414
4415 if (!Info.getLangOpts().CPlusPlus14) {
4416 Info.FFDiag(E);
4417 return false;
4418 }
4419
4420 CompleteObject Obj = findCompleteObject(Info, E, AK_Assign, LVal, LValType);
4421 CompoundAssignSubobjectHandler Handler = { Info, E, PromotedLValType, Opcode,
4422 RVal };
4423 return Obj && findSubobject(Info, E, Obj, LVal.Designator, Handler);
4424 }
4425
4426 namespace {
4427 struct IncDecSubobjectHandler {
4428 EvalInfo &Info;
4429 const UnaryOperator *E;
4430 AccessKinds AccessKind;
4431 APValue *Old;
4432
4433 typedef bool result_type;
4434
checkConst__anon4a4db2530d11::IncDecSubobjectHandler4435 bool checkConst(QualType QT) {
4436 // Assigning to a const object has undefined behavior.
4437 if (QT.isConstQualified()) {
4438 Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT;
4439 return false;
4440 }
4441 return true;
4442 }
4443
failed__anon4a4db2530d11::IncDecSubobjectHandler4444 bool failed() { return false; }
found__anon4a4db2530d11::IncDecSubobjectHandler4445 bool found(APValue &Subobj, QualType SubobjType) {
4446 // Stash the old value. Also clear Old, so we don't clobber it later
4447 // if we're post-incrementing a complex.
4448 if (Old) {
4449 *Old = Subobj;
4450 Old = nullptr;
4451 }
4452
4453 switch (Subobj.getKind()) {
4454 case APValue::Int:
4455 return found(Subobj.getInt(), SubobjType);
4456 case APValue::Float:
4457 return found(Subobj.getFloat(), SubobjType);
4458 case APValue::ComplexInt:
4459 return found(Subobj.getComplexIntReal(),
4460 SubobjType->castAs<ComplexType>()->getElementType()
4461 .withCVRQualifiers(SubobjType.getCVRQualifiers()));
4462 case APValue::ComplexFloat:
4463 return found(Subobj.getComplexFloatReal(),
4464 SubobjType->castAs<ComplexType>()->getElementType()
4465 .withCVRQualifiers(SubobjType.getCVRQualifiers()));
4466 case APValue::LValue:
4467 return foundPointer(Subobj, SubobjType);
4468 default:
4469 // FIXME: can this happen?
4470 Info.FFDiag(E);
4471 return false;
4472 }
4473 }
found__anon4a4db2530d11::IncDecSubobjectHandler4474 bool found(APSInt &Value, QualType SubobjType) {
4475 if (!checkConst(SubobjType))
4476 return false;
4477
4478 if (!SubobjType->isIntegerType()) {
4479 // We don't support increment / decrement on integer-cast-to-pointer
4480 // values.
4481 Info.FFDiag(E);
4482 return false;
4483 }
4484
4485 if (Old) *Old = APValue(Value);
4486
4487 // bool arithmetic promotes to int, and the conversion back to bool
4488 // doesn't reduce mod 2^n, so special-case it.
4489 if (SubobjType->isBooleanType()) {
4490 if (AccessKind == AK_Increment)
4491 Value = 1;
4492 else
4493 Value = !Value;
4494 return true;
4495 }
4496
4497 bool WasNegative = Value.isNegative();
4498 if (AccessKind == AK_Increment) {
4499 ++Value;
4500
4501 if (!WasNegative && Value.isNegative() && E->canOverflow()) {
4502 APSInt ActualValue(Value, /*IsUnsigned*/true);
4503 return HandleOverflow(Info, E, ActualValue, SubobjType);
4504 }
4505 } else {
4506 --Value;
4507
4508 if (WasNegative && !Value.isNegative() && E->canOverflow()) {
4509 unsigned BitWidth = Value.getBitWidth();
4510 APSInt ActualValue(Value.sext(BitWidth + 1), /*IsUnsigned*/false);
4511 ActualValue.setBit(BitWidth);
4512 return HandleOverflow(Info, E, ActualValue, SubobjType);
4513 }
4514 }
4515 return true;
4516 }
found__anon4a4db2530d11::IncDecSubobjectHandler4517 bool found(APFloat &Value, QualType SubobjType) {
4518 if (!checkConst(SubobjType))
4519 return false;
4520
4521 if (Old) *Old = APValue(Value);
4522
4523 APFloat One(Value.getSemantics(), 1);
4524 if (AccessKind == AK_Increment)
4525 Value.add(One, APFloat::rmNearestTiesToEven);
4526 else
4527 Value.subtract(One, APFloat::rmNearestTiesToEven);
4528 return true;
4529 }
foundPointer__anon4a4db2530d11::IncDecSubobjectHandler4530 bool foundPointer(APValue &Subobj, QualType SubobjType) {
4531 if (!checkConst(SubobjType))
4532 return false;
4533
4534 QualType PointeeType;
4535 if (const PointerType *PT = SubobjType->getAs<PointerType>())
4536 PointeeType = PT->getPointeeType();
4537 else {
4538 Info.FFDiag(E);
4539 return false;
4540 }
4541
4542 LValue LVal;
4543 LVal.setFrom(Info.Ctx, Subobj);
4544 if (!HandleLValueArrayAdjustment(Info, E, LVal, PointeeType,
4545 AccessKind == AK_Increment ? 1 : -1))
4546 return false;
4547 LVal.moveInto(Subobj);
4548 return true;
4549 }
4550 };
4551 } // end anonymous namespace
4552
4553 /// Perform an increment or decrement on LVal.
handleIncDec(EvalInfo & Info,const Expr * E,const LValue & LVal,QualType LValType,bool IsIncrement,APValue * Old)4554 static bool handleIncDec(EvalInfo &Info, const Expr *E, const LValue &LVal,
4555 QualType LValType, bool IsIncrement, APValue *Old) {
4556 if (LVal.Designator.Invalid)
4557 return false;
4558
4559 if (!Info.getLangOpts().CPlusPlus14) {
4560 Info.FFDiag(E);
4561 return false;
4562 }
4563
4564 AccessKinds AK = IsIncrement ? AK_Increment : AK_Decrement;
4565 CompleteObject Obj = findCompleteObject(Info, E, AK, LVal, LValType);
4566 IncDecSubobjectHandler Handler = {Info, cast<UnaryOperator>(E), AK, Old};
4567 return Obj && findSubobject(Info, E, Obj, LVal.Designator, Handler);
4568 }
4569
4570 /// Build an lvalue for the object argument of a member function call.
EvaluateObjectArgument(EvalInfo & Info,const Expr * Object,LValue & This)4571 static bool EvaluateObjectArgument(EvalInfo &Info, const Expr *Object,
4572 LValue &This) {
4573 if (Object->getType()->isPointerType() && Object->isPRValue())
4574 return EvaluatePointer(Object, This, Info);
4575
4576 if (Object->isGLValue())
4577 return EvaluateLValue(Object, This, Info);
4578
4579 if (Object->getType()->isLiteralType(Info.Ctx))
4580 return EvaluateTemporary(Object, This, Info);
4581
4582 Info.FFDiag(Object, diag::note_constexpr_nonliteral) << Object->getType();
4583 return false;
4584 }
4585
4586 /// HandleMemberPointerAccess - Evaluate a member access operation and build an
4587 /// lvalue referring to the result.
4588 ///
4589 /// \param Info - Information about the ongoing evaluation.
4590 /// \param LV - An lvalue referring to the base of the member pointer.
4591 /// \param RHS - The member pointer expression.
4592 /// \param IncludeMember - Specifies whether the member itself is included in
4593 /// the resulting LValue subobject designator. This is not possible when
4594 /// creating a bound member function.
4595 /// \return The field or method declaration to which the member pointer refers,
4596 /// or 0 if evaluation fails.
HandleMemberPointerAccess(EvalInfo & Info,QualType LVType,LValue & LV,const Expr * RHS,bool IncludeMember=true)4597 static const ValueDecl *HandleMemberPointerAccess(EvalInfo &Info,
4598 QualType LVType,
4599 LValue &LV,
4600 const Expr *RHS,
4601 bool IncludeMember = true) {
4602 MemberPtr MemPtr;
4603 if (!EvaluateMemberPointer(RHS, MemPtr, Info))
4604 return nullptr;
4605
4606 // C++11 [expr.mptr.oper]p6: If the second operand is the null pointer to
4607 // member value, the behavior is undefined.
4608 if (!MemPtr.getDecl()) {
4609 // FIXME: Specific diagnostic.
4610 Info.FFDiag(RHS);
4611 return nullptr;
4612 }
4613
4614 if (MemPtr.isDerivedMember()) {
4615 // This is a member of some derived class. Truncate LV appropriately.
4616 // The end of the derived-to-base path for the base object must match the
4617 // derived-to-base path for the member pointer.
4618 if (LV.Designator.MostDerivedPathLength + MemPtr.Path.size() >
4619 LV.Designator.Entries.size()) {
4620 Info.FFDiag(RHS);
4621 return nullptr;
4622 }
4623 unsigned PathLengthToMember =
4624 LV.Designator.Entries.size() - MemPtr.Path.size();
4625 for (unsigned I = 0, N = MemPtr.Path.size(); I != N; ++I) {
4626 const CXXRecordDecl *LVDecl = getAsBaseClass(
4627 LV.Designator.Entries[PathLengthToMember + I]);
4628 const CXXRecordDecl *MPDecl = MemPtr.Path[I];
4629 if (LVDecl->getCanonicalDecl() != MPDecl->getCanonicalDecl()) {
4630 Info.FFDiag(RHS);
4631 return nullptr;
4632 }
4633 }
4634
4635 // Truncate the lvalue to the appropriate derived class.
4636 if (!CastToDerivedClass(Info, RHS, LV, MemPtr.getContainingRecord(),
4637 PathLengthToMember))
4638 return nullptr;
4639 } else if (!MemPtr.Path.empty()) {
4640 // Extend the LValue path with the member pointer's path.
4641 LV.Designator.Entries.reserve(LV.Designator.Entries.size() +
4642 MemPtr.Path.size() + IncludeMember);
4643
4644 // Walk down to the appropriate base class.
4645 if (const PointerType *PT = LVType->getAs<PointerType>())
4646 LVType = PT->getPointeeType();
4647 const CXXRecordDecl *RD = LVType->getAsCXXRecordDecl();
4648 assert(RD && "member pointer access on non-class-type expression");
4649 // The first class in the path is that of the lvalue.
4650 for (unsigned I = 1, N = MemPtr.Path.size(); I != N; ++I) {
4651 const CXXRecordDecl *Base = MemPtr.Path[N - I - 1];
4652 if (!HandleLValueDirectBase(Info, RHS, LV, RD, Base))
4653 return nullptr;
4654 RD = Base;
4655 }
4656 // Finally cast to the class containing the member.
4657 if (!HandleLValueDirectBase(Info, RHS, LV, RD,
4658 MemPtr.getContainingRecord()))
4659 return nullptr;
4660 }
4661
4662 // Add the member. Note that we cannot build bound member functions here.
4663 if (IncludeMember) {
4664 if (const FieldDecl *FD = dyn_cast<FieldDecl>(MemPtr.getDecl())) {
4665 if (!HandleLValueMember(Info, RHS, LV, FD))
4666 return nullptr;
4667 } else if (const IndirectFieldDecl *IFD =
4668 dyn_cast<IndirectFieldDecl>(MemPtr.getDecl())) {
4669 if (!HandleLValueIndirectMember(Info, RHS, LV, IFD))
4670 return nullptr;
4671 } else {
4672 llvm_unreachable("can't construct reference to bound member function");
4673 }
4674 }
4675
4676 return MemPtr.getDecl();
4677 }
4678
HandleMemberPointerAccess(EvalInfo & Info,const BinaryOperator * BO,LValue & LV,bool IncludeMember=true)4679 static const ValueDecl *HandleMemberPointerAccess(EvalInfo &Info,
4680 const BinaryOperator *BO,
4681 LValue &LV,
4682 bool IncludeMember = true) {
4683 assert(BO->getOpcode() == BO_PtrMemD || BO->getOpcode() == BO_PtrMemI);
4684
4685 if (!EvaluateObjectArgument(Info, BO->getLHS(), LV)) {
4686 if (Info.noteFailure()) {
4687 MemberPtr MemPtr;
4688 EvaluateMemberPointer(BO->getRHS(), MemPtr, Info);
4689 }
4690 return nullptr;
4691 }
4692
4693 return HandleMemberPointerAccess(Info, BO->getLHS()->getType(), LV,
4694 BO->getRHS(), IncludeMember);
4695 }
4696
4697 /// HandleBaseToDerivedCast - Apply the given base-to-derived cast operation on
4698 /// the provided lvalue, which currently refers to the base object.
HandleBaseToDerivedCast(EvalInfo & Info,const CastExpr * E,LValue & Result)4699 static bool HandleBaseToDerivedCast(EvalInfo &Info, const CastExpr *E,
4700 LValue &Result) {
4701 SubobjectDesignator &D = Result.Designator;
4702 if (D.Invalid || !Result.checkNullPointer(Info, E, CSK_Derived))
4703 return false;
4704
4705 QualType TargetQT = E->getType();
4706 if (const PointerType *PT = TargetQT->getAs<PointerType>())
4707 TargetQT = PT->getPointeeType();
4708
4709 // Check this cast lands within the final derived-to-base subobject path.
4710 if (D.MostDerivedPathLength + E->path_size() > D.Entries.size()) {
4711 Info.CCEDiag(E, diag::note_constexpr_invalid_downcast)
4712 << D.MostDerivedType << TargetQT;
4713 return false;
4714 }
4715
4716 // Check the type of the final cast. We don't need to check the path,
4717 // since a cast can only be formed if the path is unique.
4718 unsigned NewEntriesSize = D.Entries.size() - E->path_size();
4719 const CXXRecordDecl *TargetType = TargetQT->getAsCXXRecordDecl();
4720 const CXXRecordDecl *FinalType;
4721 if (NewEntriesSize == D.MostDerivedPathLength)
4722 FinalType = D.MostDerivedType->getAsCXXRecordDecl();
4723 else
4724 FinalType = getAsBaseClass(D.Entries[NewEntriesSize - 1]);
4725 if (FinalType->getCanonicalDecl() != TargetType->getCanonicalDecl()) {
4726 Info.CCEDiag(E, diag::note_constexpr_invalid_downcast)
4727 << D.MostDerivedType << TargetQT;
4728 return false;
4729 }
4730
4731 // Truncate the lvalue to the appropriate derived class.
4732 return CastToDerivedClass(Info, E, Result, TargetType, NewEntriesSize);
4733 }
4734
4735 /// Get the value to use for a default-initialized object of type T.
4736 /// Return false if it encounters something invalid.
getDefaultInitValue(QualType T,APValue & Result)4737 static bool getDefaultInitValue(QualType T, APValue &Result) {
4738 bool Success = true;
4739 if (auto *RD = T->getAsCXXRecordDecl()) {
4740 if (RD->isInvalidDecl()) {
4741 Result = APValue();
4742 return false;
4743 }
4744 if (RD->isUnion()) {
4745 Result = APValue((const FieldDecl *)nullptr);
4746 return true;
4747 }
4748 Result = APValue(APValue::UninitStruct(), RD->getNumBases(),
4749 std::distance(RD->field_begin(), RD->field_end()));
4750
4751 unsigned Index = 0;
4752 for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
4753 End = RD->bases_end();
4754 I != End; ++I, ++Index)
4755 Success &= getDefaultInitValue(I->getType(), Result.getStructBase(Index));
4756
4757 for (const auto *I : RD->fields()) {
4758 if (I->isUnnamedBitfield())
4759 continue;
4760 Success &= getDefaultInitValue(I->getType(),
4761 Result.getStructField(I->getFieldIndex()));
4762 }
4763 return Success;
4764 }
4765
4766 if (auto *AT =
4767 dyn_cast_or_null<ConstantArrayType>(T->getAsArrayTypeUnsafe())) {
4768 Result = APValue(APValue::UninitArray(), 0, AT->getSize().getZExtValue());
4769 if (Result.hasArrayFiller())
4770 Success &=
4771 getDefaultInitValue(AT->getElementType(), Result.getArrayFiller());
4772
4773 return Success;
4774 }
4775
4776 Result = APValue::IndeterminateValue();
4777 return true;
4778 }
4779
4780 namespace {
4781 enum EvalStmtResult {
4782 /// Evaluation failed.
4783 ESR_Failed,
4784 /// Hit a 'return' statement.
4785 ESR_Returned,
4786 /// Evaluation succeeded.
4787 ESR_Succeeded,
4788 /// Hit a 'continue' statement.
4789 ESR_Continue,
4790 /// Hit a 'break' statement.
4791 ESR_Break,
4792 /// Still scanning for 'case' or 'default' statement.
4793 ESR_CaseNotFound
4794 };
4795 }
4796
EvaluateVarDecl(EvalInfo & Info,const VarDecl * VD)4797 static bool EvaluateVarDecl(EvalInfo &Info, const VarDecl *VD) {
4798 // We don't need to evaluate the initializer for a static local.
4799 if (!VD->hasLocalStorage())
4800 return true;
4801
4802 LValue Result;
4803 APValue &Val = Info.CurrentCall->createTemporary(VD, VD->getType(),
4804 ScopeKind::Block, Result);
4805
4806 const Expr *InitE = VD->getInit();
4807 if (!InitE) {
4808 if (VD->getType()->isDependentType())
4809 return Info.noteSideEffect();
4810 return getDefaultInitValue(VD->getType(), Val);
4811 }
4812 if (InitE->isValueDependent())
4813 return false;
4814
4815 if (!EvaluateInPlace(Val, Info, Result, InitE)) {
4816 // Wipe out any partially-computed value, to allow tracking that this
4817 // evaluation failed.
4818 Val = APValue();
4819 return false;
4820 }
4821
4822 return true;
4823 }
4824
EvaluateDecl(EvalInfo & Info,const Decl * D)4825 static bool EvaluateDecl(EvalInfo &Info, const Decl *D) {
4826 bool OK = true;
4827
4828 if (const VarDecl *VD = dyn_cast<VarDecl>(D))
4829 OK &= EvaluateVarDecl(Info, VD);
4830
4831 if (const DecompositionDecl *DD = dyn_cast<DecompositionDecl>(D))
4832 for (auto *BD : DD->bindings())
4833 if (auto *VD = BD->getHoldingVar())
4834 OK &= EvaluateDecl(Info, VD);
4835
4836 return OK;
4837 }
4838
EvaluateDependentExpr(const Expr * E,EvalInfo & Info)4839 static bool EvaluateDependentExpr(const Expr *E, EvalInfo &Info) {
4840 assert(E->isValueDependent());
4841 if (Info.noteSideEffect())
4842 return true;
4843 assert(E->containsErrors() && "valid value-dependent expression should never "
4844 "reach invalid code path.");
4845 return false;
4846 }
4847
4848 /// Evaluate a condition (either a variable declaration or an expression).
EvaluateCond(EvalInfo & Info,const VarDecl * CondDecl,const Expr * Cond,bool & Result)4849 static bool EvaluateCond(EvalInfo &Info, const VarDecl *CondDecl,
4850 const Expr *Cond, bool &Result) {
4851 if (Cond->isValueDependent())
4852 return false;
4853 FullExpressionRAII Scope(Info);
4854 if (CondDecl && !EvaluateDecl(Info, CondDecl))
4855 return false;
4856 if (!EvaluateAsBooleanCondition(Cond, Result, Info))
4857 return false;
4858 return Scope.destroy();
4859 }
4860
4861 namespace {
4862 /// A location where the result (returned value) of evaluating a
4863 /// statement should be stored.
4864 struct StmtResult {
4865 /// The APValue that should be filled in with the returned value.
4866 APValue &Value;
4867 /// The location containing the result, if any (used to support RVO).
4868 const LValue *Slot;
4869 };
4870
4871 struct TempVersionRAII {
4872 CallStackFrame &Frame;
4873
TempVersionRAII__anon4a4db2530f11::TempVersionRAII4874 TempVersionRAII(CallStackFrame &Frame) : Frame(Frame) {
4875 Frame.pushTempVersion();
4876 }
4877
~TempVersionRAII__anon4a4db2530f11::TempVersionRAII4878 ~TempVersionRAII() {
4879 Frame.popTempVersion();
4880 }
4881 };
4882
4883 }
4884
4885 static EvalStmtResult EvaluateStmt(StmtResult &Result, EvalInfo &Info,
4886 const Stmt *S,
4887 const SwitchCase *SC = nullptr);
4888
4889 /// Evaluate the body of a loop, and translate the result as appropriate.
EvaluateLoopBody(StmtResult & Result,EvalInfo & Info,const Stmt * Body,const SwitchCase * Case=nullptr)4890 static EvalStmtResult EvaluateLoopBody(StmtResult &Result, EvalInfo &Info,
4891 const Stmt *Body,
4892 const SwitchCase *Case = nullptr) {
4893 BlockScopeRAII Scope(Info);
4894
4895 EvalStmtResult ESR = EvaluateStmt(Result, Info, Body, Case);
4896 if (ESR != ESR_Failed && ESR != ESR_CaseNotFound && !Scope.destroy())
4897 ESR = ESR_Failed;
4898
4899 switch (ESR) {
4900 case ESR_Break:
4901 return ESR_Succeeded;
4902 case ESR_Succeeded:
4903 case ESR_Continue:
4904 return ESR_Continue;
4905 case ESR_Failed:
4906 case ESR_Returned:
4907 case ESR_CaseNotFound:
4908 return ESR;
4909 }
4910 llvm_unreachable("Invalid EvalStmtResult!");
4911 }
4912
4913 /// Evaluate a switch statement.
EvaluateSwitch(StmtResult & Result,EvalInfo & Info,const SwitchStmt * SS)4914 static EvalStmtResult EvaluateSwitch(StmtResult &Result, EvalInfo &Info,
4915 const SwitchStmt *SS) {
4916 BlockScopeRAII Scope(Info);
4917
4918 // Evaluate the switch condition.
4919 APSInt Value;
4920 {
4921 if (const Stmt *Init = SS->getInit()) {
4922 EvalStmtResult ESR = EvaluateStmt(Result, Info, Init);
4923 if (ESR != ESR_Succeeded) {
4924 if (ESR != ESR_Failed && !Scope.destroy())
4925 ESR = ESR_Failed;
4926 return ESR;
4927 }
4928 }
4929
4930 FullExpressionRAII CondScope(Info);
4931 if (SS->getConditionVariable() &&
4932 !EvaluateDecl(Info, SS->getConditionVariable()))
4933 return ESR_Failed;
4934 if (!EvaluateInteger(SS->getCond(), Value, Info))
4935 return ESR_Failed;
4936 if (!CondScope.destroy())
4937 return ESR_Failed;
4938 }
4939
4940 // Find the switch case corresponding to the value of the condition.
4941 // FIXME: Cache this lookup.
4942 const SwitchCase *Found = nullptr;
4943 for (const SwitchCase *SC = SS->getSwitchCaseList(); SC;
4944 SC = SC->getNextSwitchCase()) {
4945 if (isa<DefaultStmt>(SC)) {
4946 Found = SC;
4947 continue;
4948 }
4949
4950 const CaseStmt *CS = cast<CaseStmt>(SC);
4951 APSInt LHS = CS->getLHS()->EvaluateKnownConstInt(Info.Ctx);
4952 APSInt RHS = CS->getRHS() ? CS->getRHS()->EvaluateKnownConstInt(Info.Ctx)
4953 : LHS;
4954 if (LHS <= Value && Value <= RHS) {
4955 Found = SC;
4956 break;
4957 }
4958 }
4959
4960 if (!Found)
4961 return Scope.destroy() ? ESR_Succeeded : ESR_Failed;
4962
4963 // Search the switch body for the switch case and evaluate it from there.
4964 EvalStmtResult ESR = EvaluateStmt(Result, Info, SS->getBody(), Found);
4965 if (ESR != ESR_Failed && ESR != ESR_CaseNotFound && !Scope.destroy())
4966 return ESR_Failed;
4967
4968 switch (ESR) {
4969 case ESR_Break:
4970 return ESR_Succeeded;
4971 case ESR_Succeeded:
4972 case ESR_Continue:
4973 case ESR_Failed:
4974 case ESR_Returned:
4975 return ESR;
4976 case ESR_CaseNotFound:
4977 // This can only happen if the switch case is nested within a statement
4978 // expression. We have no intention of supporting that.
4979 Info.FFDiag(Found->getBeginLoc(),
4980 diag::note_constexpr_stmt_expr_unsupported);
4981 return ESR_Failed;
4982 }
4983 llvm_unreachable("Invalid EvalStmtResult!");
4984 }
4985
4986 // Evaluate a statement.
EvaluateStmt(StmtResult & Result,EvalInfo & Info,const Stmt * S,const SwitchCase * Case)4987 static EvalStmtResult EvaluateStmt(StmtResult &Result, EvalInfo &Info,
4988 const Stmt *S, const SwitchCase *Case) {
4989 if (!Info.nextStep(S))
4990 return ESR_Failed;
4991
4992 // If we're hunting down a 'case' or 'default' label, recurse through
4993 // substatements until we hit the label.
4994 if (Case) {
4995 switch (S->getStmtClass()) {
4996 case Stmt::CompoundStmtClass:
4997 // FIXME: Precompute which substatement of a compound statement we
4998 // would jump to, and go straight there rather than performing a
4999 // linear scan each time.
5000 case Stmt::LabelStmtClass:
5001 case Stmt::AttributedStmtClass:
5002 case Stmt::DoStmtClass:
5003 break;
5004
5005 case Stmt::CaseStmtClass:
5006 case Stmt::DefaultStmtClass:
5007 if (Case == S)
5008 Case = nullptr;
5009 break;
5010
5011 case Stmt::IfStmtClass: {
5012 // FIXME: Precompute which side of an 'if' we would jump to, and go
5013 // straight there rather than scanning both sides.
5014 const IfStmt *IS = cast<IfStmt>(S);
5015
5016 // Wrap the evaluation in a block scope, in case it's a DeclStmt
5017 // preceded by our switch label.
5018 BlockScopeRAII Scope(Info);
5019
5020 // Step into the init statement in case it brings an (uninitialized)
5021 // variable into scope.
5022 if (const Stmt *Init = IS->getInit()) {
5023 EvalStmtResult ESR = EvaluateStmt(Result, Info, Init, Case);
5024 if (ESR != ESR_CaseNotFound) {
5025 assert(ESR != ESR_Succeeded);
5026 return ESR;
5027 }
5028 }
5029
5030 // Condition variable must be initialized if it exists.
5031 // FIXME: We can skip evaluating the body if there's a condition
5032 // variable, as there can't be any case labels within it.
5033 // (The same is true for 'for' statements.)
5034
5035 EvalStmtResult ESR = EvaluateStmt(Result, Info, IS->getThen(), Case);
5036 if (ESR == ESR_Failed)
5037 return ESR;
5038 if (ESR != ESR_CaseNotFound)
5039 return Scope.destroy() ? ESR : ESR_Failed;
5040 if (!IS->getElse())
5041 return ESR_CaseNotFound;
5042
5043 ESR = EvaluateStmt(Result, Info, IS->getElse(), Case);
5044 if (ESR == ESR_Failed)
5045 return ESR;
5046 if (ESR != ESR_CaseNotFound)
5047 return Scope.destroy() ? ESR : ESR_Failed;
5048 return ESR_CaseNotFound;
5049 }
5050
5051 case Stmt::WhileStmtClass: {
5052 EvalStmtResult ESR =
5053 EvaluateLoopBody(Result, Info, cast<WhileStmt>(S)->getBody(), Case);
5054 if (ESR != ESR_Continue)
5055 return ESR;
5056 break;
5057 }
5058
5059 case Stmt::ForStmtClass: {
5060 const ForStmt *FS = cast<ForStmt>(S);
5061 BlockScopeRAII Scope(Info);
5062
5063 // Step into the init statement in case it brings an (uninitialized)
5064 // variable into scope.
5065 if (const Stmt *Init = FS->getInit()) {
5066 EvalStmtResult ESR = EvaluateStmt(Result, Info, Init, Case);
5067 if (ESR != ESR_CaseNotFound) {
5068 assert(ESR != ESR_Succeeded);
5069 return ESR;
5070 }
5071 }
5072
5073 EvalStmtResult ESR =
5074 EvaluateLoopBody(Result, Info, FS->getBody(), Case);
5075 if (ESR != ESR_Continue)
5076 return ESR;
5077 if (const auto *Inc = FS->getInc()) {
5078 if (Inc->isValueDependent()) {
5079 if (!EvaluateDependentExpr(Inc, Info))
5080 return ESR_Failed;
5081 } else {
5082 FullExpressionRAII IncScope(Info);
5083 if (!EvaluateIgnoredValue(Info, Inc) || !IncScope.destroy())
5084 return ESR_Failed;
5085 }
5086 }
5087 break;
5088 }
5089
5090 case Stmt::DeclStmtClass: {
5091 // Start the lifetime of any uninitialized variables we encounter. They
5092 // might be used by the selected branch of the switch.
5093 const DeclStmt *DS = cast<DeclStmt>(S);
5094 for (const auto *D : DS->decls()) {
5095 if (const auto *VD = dyn_cast<VarDecl>(D)) {
5096 if (VD->hasLocalStorage() && !VD->getInit())
5097 if (!EvaluateVarDecl(Info, VD))
5098 return ESR_Failed;
5099 // FIXME: If the variable has initialization that can't be jumped
5100 // over, bail out of any immediately-surrounding compound-statement
5101 // too. There can't be any case labels here.
5102 }
5103 }
5104 return ESR_CaseNotFound;
5105 }
5106
5107 default:
5108 return ESR_CaseNotFound;
5109 }
5110 }
5111
5112 switch (S->getStmtClass()) {
5113 default:
5114 if (const Expr *E = dyn_cast<Expr>(S)) {
5115 if (E->isValueDependent()) {
5116 if (!EvaluateDependentExpr(E, Info))
5117 return ESR_Failed;
5118 } else {
5119 // Don't bother evaluating beyond an expression-statement which couldn't
5120 // be evaluated.
5121 // FIXME: Do we need the FullExpressionRAII object here?
5122 // VisitExprWithCleanups should create one when necessary.
5123 FullExpressionRAII Scope(Info);
5124 if (!EvaluateIgnoredValue(Info, E) || !Scope.destroy())
5125 return ESR_Failed;
5126 }
5127 return ESR_Succeeded;
5128 }
5129
5130 Info.FFDiag(S->getBeginLoc());
5131 return ESR_Failed;
5132
5133 case Stmt::NullStmtClass:
5134 return ESR_Succeeded;
5135
5136 case Stmt::DeclStmtClass: {
5137 const DeclStmt *DS = cast<DeclStmt>(S);
5138 for (const auto *D : DS->decls()) {
5139 // Each declaration initialization is its own full-expression.
5140 FullExpressionRAII Scope(Info);
5141 if (!EvaluateDecl(Info, D) && !Info.noteFailure())
5142 return ESR_Failed;
5143 if (!Scope.destroy())
5144 return ESR_Failed;
5145 }
5146 return ESR_Succeeded;
5147 }
5148
5149 case Stmt::ReturnStmtClass: {
5150 const Expr *RetExpr = cast<ReturnStmt>(S)->getRetValue();
5151 FullExpressionRAII Scope(Info);
5152 if (RetExpr && RetExpr->isValueDependent()) {
5153 EvaluateDependentExpr(RetExpr, Info);
5154 // We know we returned, but we don't know what the value is.
5155 return ESR_Failed;
5156 }
5157 if (RetExpr &&
5158 !(Result.Slot
5159 ? EvaluateInPlace(Result.Value, Info, *Result.Slot, RetExpr)
5160 : Evaluate(Result.Value, Info, RetExpr)))
5161 return ESR_Failed;
5162 return Scope.destroy() ? ESR_Returned : ESR_Failed;
5163 }
5164
5165 case Stmt::CompoundStmtClass: {
5166 BlockScopeRAII Scope(Info);
5167
5168 const CompoundStmt *CS = cast<CompoundStmt>(S);
5169 for (const auto *BI : CS->body()) {
5170 EvalStmtResult ESR = EvaluateStmt(Result, Info, BI, Case);
5171 if (ESR == ESR_Succeeded)
5172 Case = nullptr;
5173 else if (ESR != ESR_CaseNotFound) {
5174 if (ESR != ESR_Failed && !Scope.destroy())
5175 return ESR_Failed;
5176 return ESR;
5177 }
5178 }
5179 if (Case)
5180 return ESR_CaseNotFound;
5181 return Scope.destroy() ? ESR_Succeeded : ESR_Failed;
5182 }
5183
5184 case Stmt::IfStmtClass: {
5185 const IfStmt *IS = cast<IfStmt>(S);
5186
5187 // Evaluate the condition, as either a var decl or as an expression.
5188 BlockScopeRAII Scope(Info);
5189 if (const Stmt *Init = IS->getInit()) {
5190 EvalStmtResult ESR = EvaluateStmt(Result, Info, Init);
5191 if (ESR != ESR_Succeeded) {
5192 if (ESR != ESR_Failed && !Scope.destroy())
5193 return ESR_Failed;
5194 return ESR;
5195 }
5196 }
5197 bool Cond;
5198 if (IS->isConsteval())
5199 Cond = IS->isNonNegatedConsteval();
5200 else if (!EvaluateCond(Info, IS->getConditionVariable(), IS->getCond(),
5201 Cond))
5202 return ESR_Failed;
5203
5204 if (const Stmt *SubStmt = Cond ? IS->getThen() : IS->getElse()) {
5205 EvalStmtResult ESR = EvaluateStmt(Result, Info, SubStmt);
5206 if (ESR != ESR_Succeeded) {
5207 if (ESR != ESR_Failed && !Scope.destroy())
5208 return ESR_Failed;
5209 return ESR;
5210 }
5211 }
5212 return Scope.destroy() ? ESR_Succeeded : ESR_Failed;
5213 }
5214
5215 case Stmt::WhileStmtClass: {
5216 const WhileStmt *WS = cast<WhileStmt>(S);
5217 while (true) {
5218 BlockScopeRAII Scope(Info);
5219 bool Continue;
5220 if (!EvaluateCond(Info, WS->getConditionVariable(), WS->getCond(),
5221 Continue))
5222 return ESR_Failed;
5223 if (!Continue)
5224 break;
5225
5226 EvalStmtResult ESR = EvaluateLoopBody(Result, Info, WS->getBody());
5227 if (ESR != ESR_Continue) {
5228 if (ESR != ESR_Failed && !Scope.destroy())
5229 return ESR_Failed;
5230 return ESR;
5231 }
5232 if (!Scope.destroy())
5233 return ESR_Failed;
5234 }
5235 return ESR_Succeeded;
5236 }
5237
5238 case Stmt::DoStmtClass: {
5239 const DoStmt *DS = cast<DoStmt>(S);
5240 bool Continue;
5241 do {
5242 EvalStmtResult ESR = EvaluateLoopBody(Result, Info, DS->getBody(), Case);
5243 if (ESR != ESR_Continue)
5244 return ESR;
5245 Case = nullptr;
5246
5247 if (DS->getCond()->isValueDependent()) {
5248 EvaluateDependentExpr(DS->getCond(), Info);
5249 // Bailout as we don't know whether to keep going or terminate the loop.
5250 return ESR_Failed;
5251 }
5252 FullExpressionRAII CondScope(Info);
5253 if (!EvaluateAsBooleanCondition(DS->getCond(), Continue, Info) ||
5254 !CondScope.destroy())
5255 return ESR_Failed;
5256 } while (Continue);
5257 return ESR_Succeeded;
5258 }
5259
5260 case Stmt::ForStmtClass: {
5261 const ForStmt *FS = cast<ForStmt>(S);
5262 BlockScopeRAII ForScope(Info);
5263 if (FS->getInit()) {
5264 EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getInit());
5265 if (ESR != ESR_Succeeded) {
5266 if (ESR != ESR_Failed && !ForScope.destroy())
5267 return ESR_Failed;
5268 return ESR;
5269 }
5270 }
5271 while (true) {
5272 BlockScopeRAII IterScope(Info);
5273 bool Continue = true;
5274 if (FS->getCond() && !EvaluateCond(Info, FS->getConditionVariable(),
5275 FS->getCond(), Continue))
5276 return ESR_Failed;
5277 if (!Continue)
5278 break;
5279
5280 EvalStmtResult ESR = EvaluateLoopBody(Result, Info, FS->getBody());
5281 if (ESR != ESR_Continue) {
5282 if (ESR != ESR_Failed && (!IterScope.destroy() || !ForScope.destroy()))
5283 return ESR_Failed;
5284 return ESR;
5285 }
5286
5287 if (const auto *Inc = FS->getInc()) {
5288 if (Inc->isValueDependent()) {
5289 if (!EvaluateDependentExpr(Inc, Info))
5290 return ESR_Failed;
5291 } else {
5292 FullExpressionRAII IncScope(Info);
5293 if (!EvaluateIgnoredValue(Info, Inc) || !IncScope.destroy())
5294 return ESR_Failed;
5295 }
5296 }
5297
5298 if (!IterScope.destroy())
5299 return ESR_Failed;
5300 }
5301 return ForScope.destroy() ? ESR_Succeeded : ESR_Failed;
5302 }
5303
5304 case Stmt::CXXForRangeStmtClass: {
5305 const CXXForRangeStmt *FS = cast<CXXForRangeStmt>(S);
5306 BlockScopeRAII Scope(Info);
5307
5308 // Evaluate the init-statement if present.
5309 if (FS->getInit()) {
5310 EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getInit());
5311 if (ESR != ESR_Succeeded) {
5312 if (ESR != ESR_Failed && !Scope.destroy())
5313 return ESR_Failed;
5314 return ESR;
5315 }
5316 }
5317
5318 // Initialize the __range variable.
5319 EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getRangeStmt());
5320 if (ESR != ESR_Succeeded) {
5321 if (ESR != ESR_Failed && !Scope.destroy())
5322 return ESR_Failed;
5323 return ESR;
5324 }
5325
5326 // Create the __begin and __end iterators.
5327 ESR = EvaluateStmt(Result, Info, FS->getBeginStmt());
5328 if (ESR != ESR_Succeeded) {
5329 if (ESR != ESR_Failed && !Scope.destroy())
5330 return ESR_Failed;
5331 return ESR;
5332 }
5333 ESR = EvaluateStmt(Result, Info, FS->getEndStmt());
5334 if (ESR != ESR_Succeeded) {
5335 if (ESR != ESR_Failed && !Scope.destroy())
5336 return ESR_Failed;
5337 return ESR;
5338 }
5339
5340 while (true) {
5341 // Condition: __begin != __end.
5342 {
5343 if (FS->getCond()->isValueDependent()) {
5344 EvaluateDependentExpr(FS->getCond(), Info);
5345 // We don't know whether to keep going or terminate the loop.
5346 return ESR_Failed;
5347 }
5348 bool Continue = true;
5349 FullExpressionRAII CondExpr(Info);
5350 if (!EvaluateAsBooleanCondition(FS->getCond(), Continue, Info))
5351 return ESR_Failed;
5352 if (!Continue)
5353 break;
5354 }
5355
5356 // User's variable declaration, initialized by *__begin.
5357 BlockScopeRAII InnerScope(Info);
5358 ESR = EvaluateStmt(Result, Info, FS->getLoopVarStmt());
5359 if (ESR != ESR_Succeeded) {
5360 if (ESR != ESR_Failed && (!InnerScope.destroy() || !Scope.destroy()))
5361 return ESR_Failed;
5362 return ESR;
5363 }
5364
5365 // Loop body.
5366 ESR = EvaluateLoopBody(Result, Info, FS->getBody());
5367 if (ESR != ESR_Continue) {
5368 if (ESR != ESR_Failed && (!InnerScope.destroy() || !Scope.destroy()))
5369 return ESR_Failed;
5370 return ESR;
5371 }
5372 if (FS->getInc()->isValueDependent()) {
5373 if (!EvaluateDependentExpr(FS->getInc(), Info))
5374 return ESR_Failed;
5375 } else {
5376 // Increment: ++__begin
5377 if (!EvaluateIgnoredValue(Info, FS->getInc()))
5378 return ESR_Failed;
5379 }
5380
5381 if (!InnerScope.destroy())
5382 return ESR_Failed;
5383 }
5384
5385 return Scope.destroy() ? ESR_Succeeded : ESR_Failed;
5386 }
5387
5388 case Stmt::SwitchStmtClass:
5389 return EvaluateSwitch(Result, Info, cast<SwitchStmt>(S));
5390
5391 case Stmt::ContinueStmtClass:
5392 return ESR_Continue;
5393
5394 case Stmt::BreakStmtClass:
5395 return ESR_Break;
5396
5397 case Stmt::LabelStmtClass:
5398 return EvaluateStmt(Result, Info, cast<LabelStmt>(S)->getSubStmt(), Case);
5399
5400 case Stmt::AttributedStmtClass:
5401 // As a general principle, C++11 attributes can be ignored without
5402 // any semantic impact.
5403 return EvaluateStmt(Result, Info, cast<AttributedStmt>(S)->getSubStmt(),
5404 Case);
5405
5406 case Stmt::CaseStmtClass:
5407 case Stmt::DefaultStmtClass:
5408 return EvaluateStmt(Result, Info, cast<SwitchCase>(S)->getSubStmt(), Case);
5409 case Stmt::CXXTryStmtClass:
5410 // Evaluate try blocks by evaluating all sub statements.
5411 return EvaluateStmt(Result, Info, cast<CXXTryStmt>(S)->getTryBlock(), Case);
5412 }
5413 }
5414
5415 /// CheckTrivialDefaultConstructor - Check whether a constructor is a trivial
5416 /// default constructor. If so, we'll fold it whether or not it's marked as
5417 /// constexpr. If it is marked as constexpr, we will never implicitly define it,
5418 /// so we need special handling.
CheckTrivialDefaultConstructor(EvalInfo & Info,SourceLocation Loc,const CXXConstructorDecl * CD,bool IsValueInitialization)5419 static bool CheckTrivialDefaultConstructor(EvalInfo &Info, SourceLocation Loc,
5420 const CXXConstructorDecl *CD,
5421 bool IsValueInitialization) {
5422 if (!CD->isTrivial() || !CD->isDefaultConstructor())
5423 return false;
5424
5425 // Value-initialization does not call a trivial default constructor, so such a
5426 // call is a core constant expression whether or not the constructor is
5427 // constexpr.
5428 if (!CD->isConstexpr() && !IsValueInitialization) {
5429 if (Info.getLangOpts().CPlusPlus11) {
5430 // FIXME: If DiagDecl is an implicitly-declared special member function,
5431 // we should be much more explicit about why it's not constexpr.
5432 Info.CCEDiag(Loc, diag::note_constexpr_invalid_function, 1)
5433 << /*IsConstexpr*/0 << /*IsConstructor*/1 << CD;
5434 Info.Note(CD->getLocation(), diag::note_declared_at);
5435 } else {
5436 Info.CCEDiag(Loc, diag::note_invalid_subexpr_in_const_expr);
5437 }
5438 }
5439 return true;
5440 }
5441
5442 /// CheckConstexprFunction - Check that a function can be called in a constant
5443 /// expression.
CheckConstexprFunction(EvalInfo & Info,SourceLocation CallLoc,const FunctionDecl * Declaration,const FunctionDecl * Definition,const Stmt * Body)5444 static bool CheckConstexprFunction(EvalInfo &Info, SourceLocation CallLoc,
5445 const FunctionDecl *Declaration,
5446 const FunctionDecl *Definition,
5447 const Stmt *Body) {
5448 // Potential constant expressions can contain calls to declared, but not yet
5449 // defined, constexpr functions.
5450 if (Info.checkingPotentialConstantExpression() && !Definition &&
5451 Declaration->isConstexpr())
5452 return false;
5453
5454 // Bail out if the function declaration itself is invalid. We will
5455 // have produced a relevant diagnostic while parsing it, so just
5456 // note the problematic sub-expression.
5457 if (Declaration->isInvalidDecl()) {
5458 Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr);
5459 return false;
5460 }
5461
5462 // DR1872: An instantiated virtual constexpr function can't be called in a
5463 // constant expression (prior to C++20). We can still constant-fold such a
5464 // call.
5465 if (!Info.Ctx.getLangOpts().CPlusPlus20 && isa<CXXMethodDecl>(Declaration) &&
5466 cast<CXXMethodDecl>(Declaration)->isVirtual())
5467 Info.CCEDiag(CallLoc, diag::note_constexpr_virtual_call);
5468
5469 if (Definition && Definition->isInvalidDecl()) {
5470 Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr);
5471 return false;
5472 }
5473
5474 // Can we evaluate this function call?
5475 if (Definition && Definition->isConstexpr() && Body)
5476 return true;
5477
5478 if (Info.getLangOpts().CPlusPlus11) {
5479 const FunctionDecl *DiagDecl = Definition ? Definition : Declaration;
5480
5481 // If this function is not constexpr because it is an inherited
5482 // non-constexpr constructor, diagnose that directly.
5483 auto *CD = dyn_cast<CXXConstructorDecl>(DiagDecl);
5484 if (CD && CD->isInheritingConstructor()) {
5485 auto *Inherited = CD->getInheritedConstructor().getConstructor();
5486 if (!Inherited->isConstexpr())
5487 DiagDecl = CD = Inherited;
5488 }
5489
5490 // FIXME: If DiagDecl is an implicitly-declared special member function
5491 // or an inheriting constructor, we should be much more explicit about why
5492 // it's not constexpr.
5493 if (CD && CD->isInheritingConstructor())
5494 Info.FFDiag(CallLoc, diag::note_constexpr_invalid_inhctor, 1)
5495 << CD->getInheritedConstructor().getConstructor()->getParent();
5496 else
5497 Info.FFDiag(CallLoc, diag::note_constexpr_invalid_function, 1)
5498 << DiagDecl->isConstexpr() << (bool)CD << DiagDecl;
5499 Info.Note(DiagDecl->getLocation(), diag::note_declared_at);
5500 } else {
5501 Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr);
5502 }
5503 return false;
5504 }
5505
5506 namespace {
5507 struct CheckDynamicTypeHandler {
5508 AccessKinds AccessKind;
5509 typedef bool result_type;
failed__anon4a4db2531011::CheckDynamicTypeHandler5510 bool failed() { return false; }
found__anon4a4db2531011::CheckDynamicTypeHandler5511 bool found(APValue &Subobj, QualType SubobjType) { return true; }
found__anon4a4db2531011::CheckDynamicTypeHandler5512 bool found(APSInt &Value, QualType SubobjType) { return true; }
found__anon4a4db2531011::CheckDynamicTypeHandler5513 bool found(APFloat &Value, QualType SubobjType) { return true; }
5514 };
5515 } // end anonymous namespace
5516
5517 /// Check that we can access the notional vptr of an object / determine its
5518 /// dynamic type.
checkDynamicType(EvalInfo & Info,const Expr * E,const LValue & This,AccessKinds AK,bool Polymorphic)5519 static bool checkDynamicType(EvalInfo &Info, const Expr *E, const LValue &This,
5520 AccessKinds AK, bool Polymorphic) {
5521 if (This.Designator.Invalid)
5522 return false;
5523
5524 CompleteObject Obj = findCompleteObject(Info, E, AK, This, QualType());
5525
5526 if (!Obj)
5527 return false;
5528
5529 if (!Obj.Value) {
5530 // The object is not usable in constant expressions, so we can't inspect
5531 // its value to see if it's in-lifetime or what the active union members
5532 // are. We can still check for a one-past-the-end lvalue.
5533 if (This.Designator.isOnePastTheEnd() ||
5534 This.Designator.isMostDerivedAnUnsizedArray()) {
5535 Info.FFDiag(E, This.Designator.isOnePastTheEnd()
5536 ? diag::note_constexpr_access_past_end
5537 : diag::note_constexpr_access_unsized_array)
5538 << AK;
5539 return false;
5540 } else if (Polymorphic) {
5541 // Conservatively refuse to perform a polymorphic operation if we would
5542 // not be able to read a notional 'vptr' value.
5543 APValue Val;
5544 This.moveInto(Val);
5545 QualType StarThisType =
5546 Info.Ctx.getLValueReferenceType(This.Designator.getType(Info.Ctx));
5547 Info.FFDiag(E, diag::note_constexpr_polymorphic_unknown_dynamic_type)
5548 << AK << Val.getAsString(Info.Ctx, StarThisType);
5549 return false;
5550 }
5551 return true;
5552 }
5553
5554 CheckDynamicTypeHandler Handler{AK};
5555 return Obj && findSubobject(Info, E, Obj, This.Designator, Handler);
5556 }
5557
5558 /// Check that the pointee of the 'this' pointer in a member function call is
5559 /// either within its lifetime or in its period of construction or destruction.
5560 static bool
checkNonVirtualMemberCallThisPointer(EvalInfo & Info,const Expr * E,const LValue & This,const CXXMethodDecl * NamedMember)5561 checkNonVirtualMemberCallThisPointer(EvalInfo &Info, const Expr *E,
5562 const LValue &This,
5563 const CXXMethodDecl *NamedMember) {
5564 return checkDynamicType(
5565 Info, E, This,
5566 isa<CXXDestructorDecl>(NamedMember) ? AK_Destroy : AK_MemberCall, false);
5567 }
5568
5569 struct DynamicType {
5570 /// The dynamic class type of the object.
5571 const CXXRecordDecl *Type;
5572 /// The corresponding path length in the lvalue.
5573 unsigned PathLength;
5574 };
5575
getBaseClassType(SubobjectDesignator & Designator,unsigned PathLength)5576 static const CXXRecordDecl *getBaseClassType(SubobjectDesignator &Designator,
5577 unsigned PathLength) {
5578 assert(PathLength >= Designator.MostDerivedPathLength && PathLength <=
5579 Designator.Entries.size() && "invalid path length");
5580 return (PathLength == Designator.MostDerivedPathLength)
5581 ? Designator.MostDerivedType->getAsCXXRecordDecl()
5582 : getAsBaseClass(Designator.Entries[PathLength - 1]);
5583 }
5584
5585 /// Determine the dynamic type of an object.
ComputeDynamicType(EvalInfo & Info,const Expr * E,LValue & This,AccessKinds AK)5586 static Optional<DynamicType> ComputeDynamicType(EvalInfo &Info, const Expr *E,
5587 LValue &This, AccessKinds AK) {
5588 // If we don't have an lvalue denoting an object of class type, there is no
5589 // meaningful dynamic type. (We consider objects of non-class type to have no
5590 // dynamic type.)
5591 if (!checkDynamicType(Info, E, This, AK, true))
5592 return None;
5593
5594 // Refuse to compute a dynamic type in the presence of virtual bases. This
5595 // shouldn't happen other than in constant-folding situations, since literal
5596 // types can't have virtual bases.
5597 //
5598 // Note that consumers of DynamicType assume that the type has no virtual
5599 // bases, and will need modifications if this restriction is relaxed.
5600 const CXXRecordDecl *Class =
5601 This.Designator.MostDerivedType->getAsCXXRecordDecl();
5602 if (!Class || Class->getNumVBases()) {
5603 Info.FFDiag(E);
5604 return None;
5605 }
5606
5607 // FIXME: For very deep class hierarchies, it might be beneficial to use a
5608 // binary search here instead. But the overwhelmingly common case is that
5609 // we're not in the middle of a constructor, so it probably doesn't matter
5610 // in practice.
5611 ArrayRef<APValue::LValuePathEntry> Path = This.Designator.Entries;
5612 for (unsigned PathLength = This.Designator.MostDerivedPathLength;
5613 PathLength <= Path.size(); ++PathLength) {
5614 switch (Info.isEvaluatingCtorDtor(This.getLValueBase(),
5615 Path.slice(0, PathLength))) {
5616 case ConstructionPhase::Bases:
5617 case ConstructionPhase::DestroyingBases:
5618 // We're constructing or destroying a base class. This is not the dynamic
5619 // type.
5620 break;
5621
5622 case ConstructionPhase::None:
5623 case ConstructionPhase::AfterBases:
5624 case ConstructionPhase::AfterFields:
5625 case ConstructionPhase::Destroying:
5626 // We've finished constructing the base classes and not yet started
5627 // destroying them again, so this is the dynamic type.
5628 return DynamicType{getBaseClassType(This.Designator, PathLength),
5629 PathLength};
5630 }
5631 }
5632
5633 // CWG issue 1517: we're constructing a base class of the object described by
5634 // 'This', so that object has not yet begun its period of construction and
5635 // any polymorphic operation on it results in undefined behavior.
5636 Info.FFDiag(E);
5637 return None;
5638 }
5639
5640 /// Perform virtual dispatch.
HandleVirtualDispatch(EvalInfo & Info,const Expr * E,LValue & This,const CXXMethodDecl * Found,llvm::SmallVectorImpl<QualType> & CovariantAdjustmentPath)5641 static const CXXMethodDecl *HandleVirtualDispatch(
5642 EvalInfo &Info, const Expr *E, LValue &This, const CXXMethodDecl *Found,
5643 llvm::SmallVectorImpl<QualType> &CovariantAdjustmentPath) {
5644 Optional<DynamicType> DynType = ComputeDynamicType(
5645 Info, E, This,
5646 isa<CXXDestructorDecl>(Found) ? AK_Destroy : AK_MemberCall);
5647 if (!DynType)
5648 return nullptr;
5649
5650 // Find the final overrider. It must be declared in one of the classes on the
5651 // path from the dynamic type to the static type.
5652 // FIXME: If we ever allow literal types to have virtual base classes, that
5653 // won't be true.
5654 const CXXMethodDecl *Callee = Found;
5655 unsigned PathLength = DynType->PathLength;
5656 for (/**/; PathLength <= This.Designator.Entries.size(); ++PathLength) {
5657 const CXXRecordDecl *Class = getBaseClassType(This.Designator, PathLength);
5658 const CXXMethodDecl *Overrider =
5659 Found->getCorrespondingMethodDeclaredInClass(Class, false);
5660 if (Overrider) {
5661 Callee = Overrider;
5662 break;
5663 }
5664 }
5665
5666 // C++2a [class.abstract]p6:
5667 // the effect of making a virtual call to a pure virtual function [...] is
5668 // undefined
5669 if (Callee->isPure()) {
5670 Info.FFDiag(E, diag::note_constexpr_pure_virtual_call, 1) << Callee;
5671 Info.Note(Callee->getLocation(), diag::note_declared_at);
5672 return nullptr;
5673 }
5674
5675 // If necessary, walk the rest of the path to determine the sequence of
5676 // covariant adjustment steps to apply.
5677 if (!Info.Ctx.hasSameUnqualifiedType(Callee->getReturnType(),
5678 Found->getReturnType())) {
5679 CovariantAdjustmentPath.push_back(Callee->getReturnType());
5680 for (unsigned CovariantPathLength = PathLength + 1;
5681 CovariantPathLength != This.Designator.Entries.size();
5682 ++CovariantPathLength) {
5683 const CXXRecordDecl *NextClass =
5684 getBaseClassType(This.Designator, CovariantPathLength);
5685 const CXXMethodDecl *Next =
5686 Found->getCorrespondingMethodDeclaredInClass(NextClass, false);
5687 if (Next && !Info.Ctx.hasSameUnqualifiedType(
5688 Next->getReturnType(), CovariantAdjustmentPath.back()))
5689 CovariantAdjustmentPath.push_back(Next->getReturnType());
5690 }
5691 if (!Info.Ctx.hasSameUnqualifiedType(Found->getReturnType(),
5692 CovariantAdjustmentPath.back()))
5693 CovariantAdjustmentPath.push_back(Found->getReturnType());
5694 }
5695
5696 // Perform 'this' adjustment.
5697 if (!CastToDerivedClass(Info, E, This, Callee->getParent(), PathLength))
5698 return nullptr;
5699
5700 return Callee;
5701 }
5702
5703 /// Perform the adjustment from a value returned by a virtual function to
5704 /// a value of the statically expected type, which may be a pointer or
5705 /// reference to a base class of the returned type.
HandleCovariantReturnAdjustment(EvalInfo & Info,const Expr * E,APValue & Result,ArrayRef<QualType> Path)5706 static bool HandleCovariantReturnAdjustment(EvalInfo &Info, const Expr *E,
5707 APValue &Result,
5708 ArrayRef<QualType> Path) {
5709 assert(Result.isLValue() &&
5710 "unexpected kind of APValue for covariant return");
5711 if (Result.isNullPointer())
5712 return true;
5713
5714 LValue LVal;
5715 LVal.setFrom(Info.Ctx, Result);
5716
5717 const CXXRecordDecl *OldClass = Path[0]->getPointeeCXXRecordDecl();
5718 for (unsigned I = 1; I != Path.size(); ++I) {
5719 const CXXRecordDecl *NewClass = Path[I]->getPointeeCXXRecordDecl();
5720 assert(OldClass && NewClass && "unexpected kind of covariant return");
5721 if (OldClass != NewClass &&
5722 !CastToBaseClass(Info, E, LVal, OldClass, NewClass))
5723 return false;
5724 OldClass = NewClass;
5725 }
5726
5727 LVal.moveInto(Result);
5728 return true;
5729 }
5730
5731 /// Determine whether \p Base, which is known to be a direct base class of
5732 /// \p Derived, is a public base class.
isBaseClassPublic(const CXXRecordDecl * Derived,const CXXRecordDecl * Base)5733 static bool isBaseClassPublic(const CXXRecordDecl *Derived,
5734 const CXXRecordDecl *Base) {
5735 for (const CXXBaseSpecifier &BaseSpec : Derived->bases()) {
5736 auto *BaseClass = BaseSpec.getType()->getAsCXXRecordDecl();
5737 if (BaseClass && declaresSameEntity(BaseClass, Base))
5738 return BaseSpec.getAccessSpecifier() == AS_public;
5739 }
5740 llvm_unreachable("Base is not a direct base of Derived");
5741 }
5742
5743 /// Apply the given dynamic cast operation on the provided lvalue.
5744 ///
5745 /// This implements the hard case of dynamic_cast, requiring a "runtime check"
5746 /// to find a suitable target subobject.
HandleDynamicCast(EvalInfo & Info,const ExplicitCastExpr * E,LValue & Ptr)5747 static bool HandleDynamicCast(EvalInfo &Info, const ExplicitCastExpr *E,
5748 LValue &Ptr) {
5749 // We can't do anything with a non-symbolic pointer value.
5750 SubobjectDesignator &D = Ptr.Designator;
5751 if (D.Invalid)
5752 return false;
5753
5754 // C++ [expr.dynamic.cast]p6:
5755 // If v is a null pointer value, the result is a null pointer value.
5756 if (Ptr.isNullPointer() && !E->isGLValue())
5757 return true;
5758
5759 // For all the other cases, we need the pointer to point to an object within
5760 // its lifetime / period of construction / destruction, and we need to know
5761 // its dynamic type.
5762 Optional<DynamicType> DynType =
5763 ComputeDynamicType(Info, E, Ptr, AK_DynamicCast);
5764 if (!DynType)
5765 return false;
5766
5767 // C++ [expr.dynamic.cast]p7:
5768 // If T is "pointer to cv void", then the result is a pointer to the most
5769 // derived object
5770 if (E->getType()->isVoidPointerType())
5771 return CastToDerivedClass(Info, E, Ptr, DynType->Type, DynType->PathLength);
5772
5773 const CXXRecordDecl *C = E->getTypeAsWritten()->getPointeeCXXRecordDecl();
5774 assert(C && "dynamic_cast target is not void pointer nor class");
5775 CanQualType CQT = Info.Ctx.getCanonicalType(Info.Ctx.getRecordType(C));
5776
5777 auto RuntimeCheckFailed = [&] (CXXBasePaths *Paths) {
5778 // C++ [expr.dynamic.cast]p9:
5779 if (!E->isGLValue()) {
5780 // The value of a failed cast to pointer type is the null pointer value
5781 // of the required result type.
5782 Ptr.setNull(Info.Ctx, E->getType());
5783 return true;
5784 }
5785
5786 // A failed cast to reference type throws [...] std::bad_cast.
5787 unsigned DiagKind;
5788 if (!Paths && (declaresSameEntity(DynType->Type, C) ||
5789 DynType->Type->isDerivedFrom(C)))
5790 DiagKind = 0;
5791 else if (!Paths || Paths->begin() == Paths->end())
5792 DiagKind = 1;
5793 else if (Paths->isAmbiguous(CQT))
5794 DiagKind = 2;
5795 else {
5796 assert(Paths->front().Access != AS_public && "why did the cast fail?");
5797 DiagKind = 3;
5798 }
5799 Info.FFDiag(E, diag::note_constexpr_dynamic_cast_to_reference_failed)
5800 << DiagKind << Ptr.Designator.getType(Info.Ctx)
5801 << Info.Ctx.getRecordType(DynType->Type)
5802 << E->getType().getUnqualifiedType();
5803 return false;
5804 };
5805
5806 // Runtime check, phase 1:
5807 // Walk from the base subobject towards the derived object looking for the
5808 // target type.
5809 for (int PathLength = Ptr.Designator.Entries.size();
5810 PathLength >= (int)DynType->PathLength; --PathLength) {
5811 const CXXRecordDecl *Class = getBaseClassType(Ptr.Designator, PathLength);
5812 if (declaresSameEntity(Class, C))
5813 return CastToDerivedClass(Info, E, Ptr, Class, PathLength);
5814 // We can only walk across public inheritance edges.
5815 if (PathLength > (int)DynType->PathLength &&
5816 !isBaseClassPublic(getBaseClassType(Ptr.Designator, PathLength - 1),
5817 Class))
5818 return RuntimeCheckFailed(nullptr);
5819 }
5820
5821 // Runtime check, phase 2:
5822 // Search the dynamic type for an unambiguous public base of type C.
5823 CXXBasePaths Paths(/*FindAmbiguities=*/true,
5824 /*RecordPaths=*/true, /*DetectVirtual=*/false);
5825 if (DynType->Type->isDerivedFrom(C, Paths) && !Paths.isAmbiguous(CQT) &&
5826 Paths.front().Access == AS_public) {
5827 // Downcast to the dynamic type...
5828 if (!CastToDerivedClass(Info, E, Ptr, DynType->Type, DynType->PathLength))
5829 return false;
5830 // ... then upcast to the chosen base class subobject.
5831 for (CXXBasePathElement &Elem : Paths.front())
5832 if (!HandleLValueBase(Info, E, Ptr, Elem.Class, Elem.Base))
5833 return false;
5834 return true;
5835 }
5836
5837 // Otherwise, the runtime check fails.
5838 return RuntimeCheckFailed(&Paths);
5839 }
5840
5841 namespace {
5842 struct StartLifetimeOfUnionMemberHandler {
5843 EvalInfo &Info;
5844 const Expr *LHSExpr;
5845 const FieldDecl *Field;
5846 bool DuringInit;
5847 bool Failed = false;
5848 static const AccessKinds AccessKind = AK_Assign;
5849
5850 typedef bool result_type;
failed__anon4a4db2531211::StartLifetimeOfUnionMemberHandler5851 bool failed() { return Failed; }
found__anon4a4db2531211::StartLifetimeOfUnionMemberHandler5852 bool found(APValue &Subobj, QualType SubobjType) {
5853 // We are supposed to perform no initialization but begin the lifetime of
5854 // the object. We interpret that as meaning to do what default
5855 // initialization of the object would do if all constructors involved were
5856 // trivial:
5857 // * All base, non-variant member, and array element subobjects' lifetimes
5858 // begin
5859 // * No variant members' lifetimes begin
5860 // * All scalar subobjects whose lifetimes begin have indeterminate values
5861 assert(SubobjType->isUnionType());
5862 if (declaresSameEntity(Subobj.getUnionField(), Field)) {
5863 // This union member is already active. If it's also in-lifetime, there's
5864 // nothing to do.
5865 if (Subobj.getUnionValue().hasValue())
5866 return true;
5867 } else if (DuringInit) {
5868 // We're currently in the process of initializing a different union
5869 // member. If we carried on, that initialization would attempt to
5870 // store to an inactive union member, resulting in undefined behavior.
5871 Info.FFDiag(LHSExpr,
5872 diag::note_constexpr_union_member_change_during_init);
5873 return false;
5874 }
5875 APValue Result;
5876 Failed = !getDefaultInitValue(Field->getType(), Result);
5877 Subobj.setUnion(Field, Result);
5878 return true;
5879 }
found__anon4a4db2531211::StartLifetimeOfUnionMemberHandler5880 bool found(APSInt &Value, QualType SubobjType) {
5881 llvm_unreachable("wrong value kind for union object");
5882 }
found__anon4a4db2531211::StartLifetimeOfUnionMemberHandler5883 bool found(APFloat &Value, QualType SubobjType) {
5884 llvm_unreachable("wrong value kind for union object");
5885 }
5886 };
5887 } // end anonymous namespace
5888
5889 const AccessKinds StartLifetimeOfUnionMemberHandler::AccessKind;
5890
5891 /// Handle a builtin simple-assignment or a call to a trivial assignment
5892 /// operator whose left-hand side might involve a union member access. If it
5893 /// does, implicitly start the lifetime of any accessed union elements per
5894 /// C++20 [class.union]5.
HandleUnionActiveMemberChange(EvalInfo & Info,const Expr * LHSExpr,const LValue & LHS)5895 static bool HandleUnionActiveMemberChange(EvalInfo &Info, const Expr *LHSExpr,
5896 const LValue &LHS) {
5897 if (LHS.InvalidBase || LHS.Designator.Invalid)
5898 return false;
5899
5900 llvm::SmallVector<std::pair<unsigned, const FieldDecl*>, 4> UnionPathLengths;
5901 // C++ [class.union]p5:
5902 // define the set S(E) of subexpressions of E as follows:
5903 unsigned PathLength = LHS.Designator.Entries.size();
5904 for (const Expr *E = LHSExpr; E != nullptr;) {
5905 // -- If E is of the form A.B, S(E) contains the elements of S(A)...
5906 if (auto *ME = dyn_cast<MemberExpr>(E)) {
5907 auto *FD = dyn_cast<FieldDecl>(ME->getMemberDecl());
5908 // Note that we can't implicitly start the lifetime of a reference,
5909 // so we don't need to proceed any further if we reach one.
5910 if (!FD || FD->getType()->isReferenceType())
5911 break;
5912
5913 // ... and also contains A.B if B names a union member ...
5914 if (FD->getParent()->isUnion()) {
5915 // ... of a non-class, non-array type, or of a class type with a
5916 // trivial default constructor that is not deleted, or an array of
5917 // such types.
5918 auto *RD =
5919 FD->getType()->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
5920 if (!RD || RD->hasTrivialDefaultConstructor())
5921 UnionPathLengths.push_back({PathLength - 1, FD});
5922 }
5923
5924 E = ME->getBase();
5925 --PathLength;
5926 assert(declaresSameEntity(FD,
5927 LHS.Designator.Entries[PathLength]
5928 .getAsBaseOrMember().getPointer()));
5929
5930 // -- If E is of the form A[B] and is interpreted as a built-in array
5931 // subscripting operator, S(E) is [S(the array operand, if any)].
5932 } else if (auto *ASE = dyn_cast<ArraySubscriptExpr>(E)) {
5933 // Step over an ArrayToPointerDecay implicit cast.
5934 auto *Base = ASE->getBase()->IgnoreImplicit();
5935 if (!Base->getType()->isArrayType())
5936 break;
5937
5938 E = Base;
5939 --PathLength;
5940
5941 } else if (auto *ICE = dyn_cast<ImplicitCastExpr>(E)) {
5942 // Step over a derived-to-base conversion.
5943 E = ICE->getSubExpr();
5944 if (ICE->getCastKind() == CK_NoOp)
5945 continue;
5946 if (ICE->getCastKind() != CK_DerivedToBase &&
5947 ICE->getCastKind() != CK_UncheckedDerivedToBase)
5948 break;
5949 // Walk path backwards as we walk up from the base to the derived class.
5950 for (const CXXBaseSpecifier *Elt : llvm::reverse(ICE->path())) {
5951 --PathLength;
5952 (void)Elt;
5953 assert(declaresSameEntity(Elt->getType()->getAsCXXRecordDecl(),
5954 LHS.Designator.Entries[PathLength]
5955 .getAsBaseOrMember().getPointer()));
5956 }
5957
5958 // -- Otherwise, S(E) is empty.
5959 } else {
5960 break;
5961 }
5962 }
5963
5964 // Common case: no unions' lifetimes are started.
5965 if (UnionPathLengths.empty())
5966 return true;
5967
5968 // if modification of X [would access an inactive union member], an object
5969 // of the type of X is implicitly created
5970 CompleteObject Obj =
5971 findCompleteObject(Info, LHSExpr, AK_Assign, LHS, LHSExpr->getType());
5972 if (!Obj)
5973 return false;
5974 for (std::pair<unsigned, const FieldDecl *> LengthAndField :
5975 llvm::reverse(UnionPathLengths)) {
5976 // Form a designator for the union object.
5977 SubobjectDesignator D = LHS.Designator;
5978 D.truncate(Info.Ctx, LHS.Base, LengthAndField.first);
5979
5980 bool DuringInit = Info.isEvaluatingCtorDtor(LHS.Base, D.Entries) ==
5981 ConstructionPhase::AfterBases;
5982 StartLifetimeOfUnionMemberHandler StartLifetime{
5983 Info, LHSExpr, LengthAndField.second, DuringInit};
5984 if (!findSubobject(Info, LHSExpr, Obj, D, StartLifetime))
5985 return false;
5986 }
5987
5988 return true;
5989 }
5990
EvaluateCallArg(const ParmVarDecl * PVD,const Expr * Arg,CallRef Call,EvalInfo & Info,bool NonNull=false)5991 static bool EvaluateCallArg(const ParmVarDecl *PVD, const Expr *Arg,
5992 CallRef Call, EvalInfo &Info,
5993 bool NonNull = false) {
5994 LValue LV;
5995 // Create the parameter slot and register its destruction. For a vararg
5996 // argument, create a temporary.
5997 // FIXME: For calling conventions that destroy parameters in the callee,
5998 // should we consider performing destruction when the function returns
5999 // instead?
6000 APValue &V = PVD ? Info.CurrentCall->createParam(Call, PVD, LV)
6001 : Info.CurrentCall->createTemporary(Arg, Arg->getType(),
6002 ScopeKind::Call, LV);
6003 if (!EvaluateInPlace(V, Info, LV, Arg))
6004 return false;
6005
6006 // Passing a null pointer to an __attribute__((nonnull)) parameter results in
6007 // undefined behavior, so is non-constant.
6008 if (NonNull && V.isLValue() && V.isNullPointer()) {
6009 Info.CCEDiag(Arg, diag::note_non_null_attribute_failed);
6010 return false;
6011 }
6012
6013 return true;
6014 }
6015
6016 /// Evaluate the arguments to a function call.
EvaluateArgs(ArrayRef<const Expr * > Args,CallRef Call,EvalInfo & Info,const FunctionDecl * Callee,bool RightToLeft=false)6017 static bool EvaluateArgs(ArrayRef<const Expr *> Args, CallRef Call,
6018 EvalInfo &Info, const FunctionDecl *Callee,
6019 bool RightToLeft = false) {
6020 bool Success = true;
6021 llvm::SmallBitVector ForbiddenNullArgs;
6022 if (Callee->hasAttr<NonNullAttr>()) {
6023 ForbiddenNullArgs.resize(Args.size());
6024 for (const auto *Attr : Callee->specific_attrs<NonNullAttr>()) {
6025 if (!Attr->args_size()) {
6026 ForbiddenNullArgs.set();
6027 break;
6028 } else
6029 for (auto Idx : Attr->args()) {
6030 unsigned ASTIdx = Idx.getASTIndex();
6031 if (ASTIdx >= Args.size())
6032 continue;
6033 ForbiddenNullArgs[ASTIdx] = 1;
6034 }
6035 }
6036 }
6037 for (unsigned I = 0; I < Args.size(); I++) {
6038 unsigned Idx = RightToLeft ? Args.size() - I - 1 : I;
6039 const ParmVarDecl *PVD =
6040 Idx < Callee->getNumParams() ? Callee->getParamDecl(Idx) : nullptr;
6041 bool NonNull = !ForbiddenNullArgs.empty() && ForbiddenNullArgs[Idx];
6042 if (!EvaluateCallArg(PVD, Args[Idx], Call, Info, NonNull)) {
6043 // If we're checking for a potential constant expression, evaluate all
6044 // initializers even if some of them fail.
6045 if (!Info.noteFailure())
6046 return false;
6047 Success = false;
6048 }
6049 }
6050 return Success;
6051 }
6052
6053 /// Perform a trivial copy from Param, which is the parameter of a copy or move
6054 /// constructor or assignment operator.
handleTrivialCopy(EvalInfo & Info,const ParmVarDecl * Param,const Expr * E,APValue & Result,bool CopyObjectRepresentation)6055 static bool handleTrivialCopy(EvalInfo &Info, const ParmVarDecl *Param,
6056 const Expr *E, APValue &Result,
6057 bool CopyObjectRepresentation) {
6058 // Find the reference argument.
6059 CallStackFrame *Frame = Info.CurrentCall;
6060 APValue *RefValue = Info.getParamSlot(Frame->Arguments, Param);
6061 if (!RefValue) {
6062 Info.FFDiag(E);
6063 return false;
6064 }
6065
6066 // Copy out the contents of the RHS object.
6067 LValue RefLValue;
6068 RefLValue.setFrom(Info.Ctx, *RefValue);
6069 return handleLValueToRValueConversion(
6070 Info, E, Param->getType().getNonReferenceType(), RefLValue, Result,
6071 CopyObjectRepresentation);
6072 }
6073
6074 /// Evaluate a function call.
HandleFunctionCall(SourceLocation CallLoc,const FunctionDecl * Callee,const LValue * This,ArrayRef<const Expr * > Args,CallRef Call,const Stmt * Body,EvalInfo & Info,APValue & Result,const LValue * ResultSlot)6075 static bool HandleFunctionCall(SourceLocation CallLoc,
6076 const FunctionDecl *Callee, const LValue *This,
6077 ArrayRef<const Expr *> Args, CallRef Call,
6078 const Stmt *Body, EvalInfo &Info,
6079 APValue &Result, const LValue *ResultSlot) {
6080 if (!Info.CheckCallLimit(CallLoc))
6081 return false;
6082
6083 CallStackFrame Frame(Info, CallLoc, Callee, This, Call);
6084
6085 // For a trivial copy or move assignment, perform an APValue copy. This is
6086 // essential for unions, where the operations performed by the assignment
6087 // operator cannot be represented as statements.
6088 //
6089 // Skip this for non-union classes with no fields; in that case, the defaulted
6090 // copy/move does not actually read the object.
6091 const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(Callee);
6092 if (MD && MD->isDefaulted() &&
6093 (MD->getParent()->isUnion() ||
6094 (MD->isTrivial() &&
6095 isReadByLvalueToRvalueConversion(MD->getParent())))) {
6096 assert(This &&
6097 (MD->isCopyAssignmentOperator() || MD->isMoveAssignmentOperator()));
6098 APValue RHSValue;
6099 if (!handleTrivialCopy(Info, MD->getParamDecl(0), Args[0], RHSValue,
6100 MD->getParent()->isUnion()))
6101 return false;
6102 if (Info.getLangOpts().CPlusPlus20 && MD->isTrivial() &&
6103 !HandleUnionActiveMemberChange(Info, Args[0], *This))
6104 return false;
6105 if (!handleAssignment(Info, Args[0], *This, MD->getThisType(),
6106 RHSValue))
6107 return false;
6108 This->moveInto(Result);
6109 return true;
6110 } else if (MD && isLambdaCallOperator(MD)) {
6111 // We're in a lambda; determine the lambda capture field maps unless we're
6112 // just constexpr checking a lambda's call operator. constexpr checking is
6113 // done before the captures have been added to the closure object (unless
6114 // we're inferring constexpr-ness), so we don't have access to them in this
6115 // case. But since we don't need the captures to constexpr check, we can
6116 // just ignore them.
6117 if (!Info.checkingPotentialConstantExpression())
6118 MD->getParent()->getCaptureFields(Frame.LambdaCaptureFields,
6119 Frame.LambdaThisCaptureField);
6120 }
6121
6122 StmtResult Ret = {Result, ResultSlot};
6123 EvalStmtResult ESR = EvaluateStmt(Ret, Info, Body);
6124 if (ESR == ESR_Succeeded) {
6125 if (Callee->getReturnType()->isVoidType())
6126 return true;
6127 Info.FFDiag(Callee->getEndLoc(), diag::note_constexpr_no_return);
6128 }
6129 return ESR == ESR_Returned;
6130 }
6131
6132 /// Evaluate a constructor call.
HandleConstructorCall(const Expr * E,const LValue & This,CallRef Call,const CXXConstructorDecl * Definition,EvalInfo & Info,APValue & Result)6133 static bool HandleConstructorCall(const Expr *E, const LValue &This,
6134 CallRef Call,
6135 const CXXConstructorDecl *Definition,
6136 EvalInfo &Info, APValue &Result) {
6137 SourceLocation CallLoc = E->getExprLoc();
6138 if (!Info.CheckCallLimit(CallLoc))
6139 return false;
6140
6141 const CXXRecordDecl *RD = Definition->getParent();
6142 if (RD->getNumVBases()) {
6143 Info.FFDiag(CallLoc, diag::note_constexpr_virtual_base) << RD;
6144 return false;
6145 }
6146
6147 EvalInfo::EvaluatingConstructorRAII EvalObj(
6148 Info,
6149 ObjectUnderConstruction{This.getLValueBase(), This.Designator.Entries},
6150 RD->getNumBases());
6151 CallStackFrame Frame(Info, CallLoc, Definition, &This, Call);
6152
6153 // FIXME: Creating an APValue just to hold a nonexistent return value is
6154 // wasteful.
6155 APValue RetVal;
6156 StmtResult Ret = {RetVal, nullptr};
6157
6158 // If it's a delegating constructor, delegate.
6159 if (Definition->isDelegatingConstructor()) {
6160 CXXConstructorDecl::init_const_iterator I = Definition->init_begin();
6161 if ((*I)->getInit()->isValueDependent()) {
6162 if (!EvaluateDependentExpr((*I)->getInit(), Info))
6163 return false;
6164 } else {
6165 FullExpressionRAII InitScope(Info);
6166 if (!EvaluateInPlace(Result, Info, This, (*I)->getInit()) ||
6167 !InitScope.destroy())
6168 return false;
6169 }
6170 return EvaluateStmt(Ret, Info, Definition->getBody()) != ESR_Failed;
6171 }
6172
6173 // For a trivial copy or move constructor, perform an APValue copy. This is
6174 // essential for unions (or classes with anonymous union members), where the
6175 // operations performed by the constructor cannot be represented by
6176 // ctor-initializers.
6177 //
6178 // Skip this for empty non-union classes; we should not perform an
6179 // lvalue-to-rvalue conversion on them because their copy constructor does not
6180 // actually read them.
6181 if (Definition->isDefaulted() && Definition->isCopyOrMoveConstructor() &&
6182 (Definition->getParent()->isUnion() ||
6183 (Definition->isTrivial() &&
6184 isReadByLvalueToRvalueConversion(Definition->getParent())))) {
6185 return handleTrivialCopy(Info, Definition->getParamDecl(0), E, Result,
6186 Definition->getParent()->isUnion());
6187 }
6188
6189 // Reserve space for the struct members.
6190 if (!Result.hasValue()) {
6191 if (!RD->isUnion())
6192 Result = APValue(APValue::UninitStruct(), RD->getNumBases(),
6193 std::distance(RD->field_begin(), RD->field_end()));
6194 else
6195 // A union starts with no active member.
6196 Result = APValue((const FieldDecl*)nullptr);
6197 }
6198
6199 if (RD->isInvalidDecl()) return false;
6200 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
6201
6202 // A scope for temporaries lifetime-extended by reference members.
6203 BlockScopeRAII LifetimeExtendedScope(Info);
6204
6205 bool Success = true;
6206 unsigned BasesSeen = 0;
6207 #ifndef NDEBUG
6208 CXXRecordDecl::base_class_const_iterator BaseIt = RD->bases_begin();
6209 #endif
6210 CXXRecordDecl::field_iterator FieldIt = RD->field_begin();
6211 auto SkipToField = [&](FieldDecl *FD, bool Indirect) {
6212 // We might be initializing the same field again if this is an indirect
6213 // field initialization.
6214 if (FieldIt == RD->field_end() ||
6215 FieldIt->getFieldIndex() > FD->getFieldIndex()) {
6216 assert(Indirect && "fields out of order?");
6217 return;
6218 }
6219
6220 // Default-initialize any fields with no explicit initializer.
6221 for (; !declaresSameEntity(*FieldIt, FD); ++FieldIt) {
6222 assert(FieldIt != RD->field_end() && "missing field?");
6223 if (!FieldIt->isUnnamedBitfield())
6224 Success &= getDefaultInitValue(
6225 FieldIt->getType(),
6226 Result.getStructField(FieldIt->getFieldIndex()));
6227 }
6228 ++FieldIt;
6229 };
6230 for (const auto *I : Definition->inits()) {
6231 LValue Subobject = This;
6232 LValue SubobjectParent = This;
6233 APValue *Value = &Result;
6234
6235 // Determine the subobject to initialize.
6236 FieldDecl *FD = nullptr;
6237 if (I->isBaseInitializer()) {
6238 QualType BaseType(I->getBaseClass(), 0);
6239 #ifndef NDEBUG
6240 // Non-virtual base classes are initialized in the order in the class
6241 // definition. We have already checked for virtual base classes.
6242 assert(!BaseIt->isVirtual() && "virtual base for literal type");
6243 assert(Info.Ctx.hasSameType(BaseIt->getType(), BaseType) &&
6244 "base class initializers not in expected order");
6245 ++BaseIt;
6246 #endif
6247 if (!HandleLValueDirectBase(Info, I->getInit(), Subobject, RD,
6248 BaseType->getAsCXXRecordDecl(), &Layout))
6249 return false;
6250 Value = &Result.getStructBase(BasesSeen++);
6251 } else if ((FD = I->getMember())) {
6252 if (!HandleLValueMember(Info, I->getInit(), Subobject, FD, &Layout))
6253 return false;
6254 if (RD->isUnion()) {
6255 Result = APValue(FD);
6256 Value = &Result.getUnionValue();
6257 } else {
6258 SkipToField(FD, false);
6259 Value = &Result.getStructField(FD->getFieldIndex());
6260 }
6261 } else if (IndirectFieldDecl *IFD = I->getIndirectMember()) {
6262 // Walk the indirect field decl's chain to find the object to initialize,
6263 // and make sure we've initialized every step along it.
6264 auto IndirectFieldChain = IFD->chain();
6265 for (auto *C : IndirectFieldChain) {
6266 FD = cast<FieldDecl>(C);
6267 CXXRecordDecl *CD = cast<CXXRecordDecl>(FD->getParent());
6268 // Switch the union field if it differs. This happens if we had
6269 // preceding zero-initialization, and we're now initializing a union
6270 // subobject other than the first.
6271 // FIXME: In this case, the values of the other subobjects are
6272 // specified, since zero-initialization sets all padding bits to zero.
6273 if (!Value->hasValue() ||
6274 (Value->isUnion() && Value->getUnionField() != FD)) {
6275 if (CD->isUnion())
6276 *Value = APValue(FD);
6277 else
6278 // FIXME: This immediately starts the lifetime of all members of
6279 // an anonymous struct. It would be preferable to strictly start
6280 // member lifetime in initialization order.
6281 Success &= getDefaultInitValue(Info.Ctx.getRecordType(CD), *Value);
6282 }
6283 // Store Subobject as its parent before updating it for the last element
6284 // in the chain.
6285 if (C == IndirectFieldChain.back())
6286 SubobjectParent = Subobject;
6287 if (!HandleLValueMember(Info, I->getInit(), Subobject, FD))
6288 return false;
6289 if (CD->isUnion())
6290 Value = &Value->getUnionValue();
6291 else {
6292 if (C == IndirectFieldChain.front() && !RD->isUnion())
6293 SkipToField(FD, true);
6294 Value = &Value->getStructField(FD->getFieldIndex());
6295 }
6296 }
6297 } else {
6298 llvm_unreachable("unknown base initializer kind");
6299 }
6300
6301 // Need to override This for implicit field initializers as in this case
6302 // This refers to innermost anonymous struct/union containing initializer,
6303 // not to currently constructed class.
6304 const Expr *Init = I->getInit();
6305 if (Init->isValueDependent()) {
6306 if (!EvaluateDependentExpr(Init, Info))
6307 return false;
6308 } else {
6309 ThisOverrideRAII ThisOverride(*Info.CurrentCall, &SubobjectParent,
6310 isa<CXXDefaultInitExpr>(Init));
6311 FullExpressionRAII InitScope(Info);
6312 if (!EvaluateInPlace(*Value, Info, Subobject, Init) ||
6313 (FD && FD->isBitField() &&
6314 !truncateBitfieldValue(Info, Init, *Value, FD))) {
6315 // If we're checking for a potential constant expression, evaluate all
6316 // initializers even if some of them fail.
6317 if (!Info.noteFailure())
6318 return false;
6319 Success = false;
6320 }
6321 }
6322
6323 // This is the point at which the dynamic type of the object becomes this
6324 // class type.
6325 if (I->isBaseInitializer() && BasesSeen == RD->getNumBases())
6326 EvalObj.finishedConstructingBases();
6327 }
6328
6329 // Default-initialize any remaining fields.
6330 if (!RD->isUnion()) {
6331 for (; FieldIt != RD->field_end(); ++FieldIt) {
6332 if (!FieldIt->isUnnamedBitfield())
6333 Success &= getDefaultInitValue(
6334 FieldIt->getType(),
6335 Result.getStructField(FieldIt->getFieldIndex()));
6336 }
6337 }
6338
6339 EvalObj.finishedConstructingFields();
6340
6341 return Success &&
6342 EvaluateStmt(Ret, Info, Definition->getBody()) != ESR_Failed &&
6343 LifetimeExtendedScope.destroy();
6344 }
6345
HandleConstructorCall(const Expr * E,const LValue & This,ArrayRef<const Expr * > Args,const CXXConstructorDecl * Definition,EvalInfo & Info,APValue & Result)6346 static bool HandleConstructorCall(const Expr *E, const LValue &This,
6347 ArrayRef<const Expr*> Args,
6348 const CXXConstructorDecl *Definition,
6349 EvalInfo &Info, APValue &Result) {
6350 CallScopeRAII CallScope(Info);
6351 CallRef Call = Info.CurrentCall->createCall(Definition);
6352 if (!EvaluateArgs(Args, Call, Info, Definition))
6353 return false;
6354
6355 return HandleConstructorCall(E, This, Call, Definition, Info, Result) &&
6356 CallScope.destroy();
6357 }
6358
HandleDestructionImpl(EvalInfo & Info,SourceLocation CallLoc,const LValue & This,APValue & Value,QualType T)6359 static bool HandleDestructionImpl(EvalInfo &Info, SourceLocation CallLoc,
6360 const LValue &This, APValue &Value,
6361 QualType T) {
6362 // Objects can only be destroyed while they're within their lifetimes.
6363 // FIXME: We have no representation for whether an object of type nullptr_t
6364 // is in its lifetime; it usually doesn't matter. Perhaps we should model it
6365 // as indeterminate instead?
6366 if (Value.isAbsent() && !T->isNullPtrType()) {
6367 APValue Printable;
6368 This.moveInto(Printable);
6369 Info.FFDiag(CallLoc, diag::note_constexpr_destroy_out_of_lifetime)
6370 << Printable.getAsString(Info.Ctx, Info.Ctx.getLValueReferenceType(T));
6371 return false;
6372 }
6373
6374 // Invent an expression for location purposes.
6375 // FIXME: We shouldn't need to do this.
6376 OpaqueValueExpr LocE(CallLoc, Info.Ctx.IntTy, VK_PRValue);
6377
6378 // For arrays, destroy elements right-to-left.
6379 if (const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(T)) {
6380 uint64_t Size = CAT->getSize().getZExtValue();
6381 QualType ElemT = CAT->getElementType();
6382
6383 LValue ElemLV = This;
6384 ElemLV.addArray(Info, &LocE, CAT);
6385 if (!HandleLValueArrayAdjustment(Info, &LocE, ElemLV, ElemT, Size))
6386 return false;
6387
6388 // Ensure that we have actual array elements available to destroy; the
6389 // destructors might mutate the value, so we can't run them on the array
6390 // filler.
6391 if (Size && Size > Value.getArrayInitializedElts())
6392 expandArray(Value, Value.getArraySize() - 1);
6393
6394 for (; Size != 0; --Size) {
6395 APValue &Elem = Value.getArrayInitializedElt(Size - 1);
6396 if (!HandleLValueArrayAdjustment(Info, &LocE, ElemLV, ElemT, -1) ||
6397 !HandleDestructionImpl(Info, CallLoc, ElemLV, Elem, ElemT))
6398 return false;
6399 }
6400
6401 // End the lifetime of this array now.
6402 Value = APValue();
6403 return true;
6404 }
6405
6406 const CXXRecordDecl *RD = T->getAsCXXRecordDecl();
6407 if (!RD) {
6408 if (T.isDestructedType()) {
6409 Info.FFDiag(CallLoc, diag::note_constexpr_unsupported_destruction) << T;
6410 return false;
6411 }
6412
6413 Value = APValue();
6414 return true;
6415 }
6416
6417 if (RD->getNumVBases()) {
6418 Info.FFDiag(CallLoc, diag::note_constexpr_virtual_base) << RD;
6419 return false;
6420 }
6421
6422 const CXXDestructorDecl *DD = RD->getDestructor();
6423 if (!DD && !RD->hasTrivialDestructor()) {
6424 Info.FFDiag(CallLoc);
6425 return false;
6426 }
6427
6428 if (!DD || DD->isTrivial() ||
6429 (RD->isAnonymousStructOrUnion() && RD->isUnion())) {
6430 // A trivial destructor just ends the lifetime of the object. Check for
6431 // this case before checking for a body, because we might not bother
6432 // building a body for a trivial destructor. Note that it doesn't matter
6433 // whether the destructor is constexpr in this case; all trivial
6434 // destructors are constexpr.
6435 //
6436 // If an anonymous union would be destroyed, some enclosing destructor must
6437 // have been explicitly defined, and the anonymous union destruction should
6438 // have no effect.
6439 Value = APValue();
6440 return true;
6441 }
6442
6443 if (!Info.CheckCallLimit(CallLoc))
6444 return false;
6445
6446 const FunctionDecl *Definition = nullptr;
6447 const Stmt *Body = DD->getBody(Definition);
6448
6449 if (!CheckConstexprFunction(Info, CallLoc, DD, Definition, Body))
6450 return false;
6451
6452 CallStackFrame Frame(Info, CallLoc, Definition, &This, CallRef());
6453
6454 // We're now in the period of destruction of this object.
6455 unsigned BasesLeft = RD->getNumBases();
6456 EvalInfo::EvaluatingDestructorRAII EvalObj(
6457 Info,
6458 ObjectUnderConstruction{This.getLValueBase(), This.Designator.Entries});
6459 if (!EvalObj.DidInsert) {
6460 // C++2a [class.dtor]p19:
6461 // the behavior is undefined if the destructor is invoked for an object
6462 // whose lifetime has ended
6463 // (Note that formally the lifetime ends when the period of destruction
6464 // begins, even though certain uses of the object remain valid until the
6465 // period of destruction ends.)
6466 Info.FFDiag(CallLoc, diag::note_constexpr_double_destroy);
6467 return false;
6468 }
6469
6470 // FIXME: Creating an APValue just to hold a nonexistent return value is
6471 // wasteful.
6472 APValue RetVal;
6473 StmtResult Ret = {RetVal, nullptr};
6474 if (EvaluateStmt(Ret, Info, Definition->getBody()) == ESR_Failed)
6475 return false;
6476
6477 // A union destructor does not implicitly destroy its members.
6478 if (RD->isUnion())
6479 return true;
6480
6481 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
6482
6483 // We don't have a good way to iterate fields in reverse, so collect all the
6484 // fields first and then walk them backwards.
6485 SmallVector<FieldDecl*, 16> Fields(RD->field_begin(), RD->field_end());
6486 for (const FieldDecl *FD : llvm::reverse(Fields)) {
6487 if (FD->isUnnamedBitfield())
6488 continue;
6489
6490 LValue Subobject = This;
6491 if (!HandleLValueMember(Info, &LocE, Subobject, FD, &Layout))
6492 return false;
6493
6494 APValue *SubobjectValue = &Value.getStructField(FD->getFieldIndex());
6495 if (!HandleDestructionImpl(Info, CallLoc, Subobject, *SubobjectValue,
6496 FD->getType()))
6497 return false;
6498 }
6499
6500 if (BasesLeft != 0)
6501 EvalObj.startedDestroyingBases();
6502
6503 // Destroy base classes in reverse order.
6504 for (const CXXBaseSpecifier &Base : llvm::reverse(RD->bases())) {
6505 --BasesLeft;
6506
6507 QualType BaseType = Base.getType();
6508 LValue Subobject = This;
6509 if (!HandleLValueDirectBase(Info, &LocE, Subobject, RD,
6510 BaseType->getAsCXXRecordDecl(), &Layout))
6511 return false;
6512
6513 APValue *SubobjectValue = &Value.getStructBase(BasesLeft);
6514 if (!HandleDestructionImpl(Info, CallLoc, Subobject, *SubobjectValue,
6515 BaseType))
6516 return false;
6517 }
6518 assert(BasesLeft == 0 && "NumBases was wrong?");
6519
6520 // The period of destruction ends now. The object is gone.
6521 Value = APValue();
6522 return true;
6523 }
6524
6525 namespace {
6526 struct DestroyObjectHandler {
6527 EvalInfo &Info;
6528 const Expr *E;
6529 const LValue &This;
6530 const AccessKinds AccessKind;
6531
6532 typedef bool result_type;
failed__anon4a4db2531411::DestroyObjectHandler6533 bool failed() { return false; }
found__anon4a4db2531411::DestroyObjectHandler6534 bool found(APValue &Subobj, QualType SubobjType) {
6535 return HandleDestructionImpl(Info, E->getExprLoc(), This, Subobj,
6536 SubobjType);
6537 }
found__anon4a4db2531411::DestroyObjectHandler6538 bool found(APSInt &Value, QualType SubobjType) {
6539 Info.FFDiag(E, diag::note_constexpr_destroy_complex_elem);
6540 return false;
6541 }
found__anon4a4db2531411::DestroyObjectHandler6542 bool found(APFloat &Value, QualType SubobjType) {
6543 Info.FFDiag(E, diag::note_constexpr_destroy_complex_elem);
6544 return false;
6545 }
6546 };
6547 }
6548
6549 /// Perform a destructor or pseudo-destructor call on the given object, which
6550 /// might in general not be a complete object.
HandleDestruction(EvalInfo & Info,const Expr * E,const LValue & This,QualType ThisType)6551 static bool HandleDestruction(EvalInfo &Info, const Expr *E,
6552 const LValue &This, QualType ThisType) {
6553 CompleteObject Obj = findCompleteObject(Info, E, AK_Destroy, This, ThisType);
6554 DestroyObjectHandler Handler = {Info, E, This, AK_Destroy};
6555 return Obj && findSubobject(Info, E, Obj, This.Designator, Handler);
6556 }
6557
6558 /// Destroy and end the lifetime of the given complete object.
HandleDestruction(EvalInfo & Info,SourceLocation Loc,APValue::LValueBase LVBase,APValue & Value,QualType T)6559 static bool HandleDestruction(EvalInfo &Info, SourceLocation Loc,
6560 APValue::LValueBase LVBase, APValue &Value,
6561 QualType T) {
6562 // If we've had an unmodeled side-effect, we can't rely on mutable state
6563 // (such as the object we're about to destroy) being correct.
6564 if (Info.EvalStatus.HasSideEffects)
6565 return false;
6566
6567 LValue LV;
6568 LV.set({LVBase});
6569 return HandleDestructionImpl(Info, Loc, LV, Value, T);
6570 }
6571
6572 /// Perform a call to 'perator new' or to `__builtin_operator_new'.
HandleOperatorNewCall(EvalInfo & Info,const CallExpr * E,LValue & Result)6573 static bool HandleOperatorNewCall(EvalInfo &Info, const CallExpr *E,
6574 LValue &Result) {
6575 if (Info.checkingPotentialConstantExpression() ||
6576 Info.SpeculativeEvaluationDepth)
6577 return false;
6578
6579 // This is permitted only within a call to std::allocator<T>::allocate.
6580 auto Caller = Info.getStdAllocatorCaller("allocate");
6581 if (!Caller) {
6582 Info.FFDiag(E->getExprLoc(), Info.getLangOpts().CPlusPlus20
6583 ? diag::note_constexpr_new_untyped
6584 : diag::note_constexpr_new);
6585 return false;
6586 }
6587
6588 QualType ElemType = Caller.ElemType;
6589 if (ElemType->isIncompleteType() || ElemType->isFunctionType()) {
6590 Info.FFDiag(E->getExprLoc(),
6591 diag::note_constexpr_new_not_complete_object_type)
6592 << (ElemType->isIncompleteType() ? 0 : 1) << ElemType;
6593 return false;
6594 }
6595
6596 APSInt ByteSize;
6597 if (!EvaluateInteger(E->getArg(0), ByteSize, Info))
6598 return false;
6599 bool IsNothrow = false;
6600 for (unsigned I = 1, N = E->getNumArgs(); I != N; ++I) {
6601 EvaluateIgnoredValue(Info, E->getArg(I));
6602 IsNothrow |= E->getType()->isNothrowT();
6603 }
6604
6605 CharUnits ElemSize;
6606 if (!HandleSizeof(Info, E->getExprLoc(), ElemType, ElemSize))
6607 return false;
6608 APInt Size, Remainder;
6609 APInt ElemSizeAP(ByteSize.getBitWidth(), ElemSize.getQuantity());
6610 APInt::udivrem(ByteSize, ElemSizeAP, Size, Remainder);
6611 if (Remainder != 0) {
6612 // This likely indicates a bug in the implementation of 'std::allocator'.
6613 Info.FFDiag(E->getExprLoc(), diag::note_constexpr_operator_new_bad_size)
6614 << ByteSize << APSInt(ElemSizeAP, true) << ElemType;
6615 return false;
6616 }
6617
6618 if (ByteSize.getActiveBits() > ConstantArrayType::getMaxSizeBits(Info.Ctx)) {
6619 if (IsNothrow) {
6620 Result.setNull(Info.Ctx, E->getType());
6621 return true;
6622 }
6623
6624 Info.FFDiag(E, diag::note_constexpr_new_too_large) << APSInt(Size, true);
6625 return false;
6626 }
6627
6628 QualType AllocType = Info.Ctx.getConstantArrayType(ElemType, Size, nullptr,
6629 ArrayType::Normal, 0);
6630 APValue *Val = Info.createHeapAlloc(E, AllocType, Result);
6631 *Val = APValue(APValue::UninitArray(), 0, Size.getZExtValue());
6632 Result.addArray(Info, E, cast<ConstantArrayType>(AllocType));
6633 return true;
6634 }
6635
hasVirtualDestructor(QualType T)6636 static bool hasVirtualDestructor(QualType T) {
6637 if (CXXRecordDecl *RD = T->getAsCXXRecordDecl())
6638 if (CXXDestructorDecl *DD = RD->getDestructor())
6639 return DD->isVirtual();
6640 return false;
6641 }
6642
getVirtualOperatorDelete(QualType T)6643 static const FunctionDecl *getVirtualOperatorDelete(QualType T) {
6644 if (CXXRecordDecl *RD = T->getAsCXXRecordDecl())
6645 if (CXXDestructorDecl *DD = RD->getDestructor())
6646 return DD->isVirtual() ? DD->getOperatorDelete() : nullptr;
6647 return nullptr;
6648 }
6649
6650 /// Check that the given object is a suitable pointer to a heap allocation that
6651 /// still exists and is of the right kind for the purpose of a deletion.
6652 ///
6653 /// On success, returns the heap allocation to deallocate. On failure, produces
6654 /// a diagnostic and returns None.
CheckDeleteKind(EvalInfo & Info,const Expr * E,const LValue & Pointer,DynAlloc::Kind DeallocKind)6655 static Optional<DynAlloc *> CheckDeleteKind(EvalInfo &Info, const Expr *E,
6656 const LValue &Pointer,
6657 DynAlloc::Kind DeallocKind) {
6658 auto PointerAsString = [&] {
6659 return Pointer.toString(Info.Ctx, Info.Ctx.VoidPtrTy);
6660 };
6661
6662 DynamicAllocLValue DA = Pointer.Base.dyn_cast<DynamicAllocLValue>();
6663 if (!DA) {
6664 Info.FFDiag(E, diag::note_constexpr_delete_not_heap_alloc)
6665 << PointerAsString();
6666 if (Pointer.Base)
6667 NoteLValueLocation(Info, Pointer.Base);
6668 return None;
6669 }
6670
6671 Optional<DynAlloc *> Alloc = Info.lookupDynamicAlloc(DA);
6672 if (!Alloc) {
6673 Info.FFDiag(E, diag::note_constexpr_double_delete);
6674 return None;
6675 }
6676
6677 QualType AllocType = Pointer.Base.getDynamicAllocType();
6678 if (DeallocKind != (*Alloc)->getKind()) {
6679 Info.FFDiag(E, diag::note_constexpr_new_delete_mismatch)
6680 << DeallocKind << (*Alloc)->getKind() << AllocType;
6681 NoteLValueLocation(Info, Pointer.Base);
6682 return None;
6683 }
6684
6685 bool Subobject = false;
6686 if (DeallocKind == DynAlloc::New) {
6687 Subobject = Pointer.Designator.MostDerivedPathLength != 0 ||
6688 Pointer.Designator.isOnePastTheEnd();
6689 } else {
6690 Subobject = Pointer.Designator.Entries.size() != 1 ||
6691 Pointer.Designator.Entries[0].getAsArrayIndex() != 0;
6692 }
6693 if (Subobject) {
6694 Info.FFDiag(E, diag::note_constexpr_delete_subobject)
6695 << PointerAsString() << Pointer.Designator.isOnePastTheEnd();
6696 return None;
6697 }
6698
6699 return Alloc;
6700 }
6701
6702 // Perform a call to 'operator delete' or '__builtin_operator_delete'.
HandleOperatorDeleteCall(EvalInfo & Info,const CallExpr * E)6703 bool HandleOperatorDeleteCall(EvalInfo &Info, const CallExpr *E) {
6704 if (Info.checkingPotentialConstantExpression() ||
6705 Info.SpeculativeEvaluationDepth)
6706 return false;
6707
6708 // This is permitted only within a call to std::allocator<T>::deallocate.
6709 if (!Info.getStdAllocatorCaller("deallocate")) {
6710 Info.FFDiag(E->getExprLoc());
6711 return true;
6712 }
6713
6714 LValue Pointer;
6715 if (!EvaluatePointer(E->getArg(0), Pointer, Info))
6716 return false;
6717 for (unsigned I = 1, N = E->getNumArgs(); I != N; ++I)
6718 EvaluateIgnoredValue(Info, E->getArg(I));
6719
6720 if (Pointer.Designator.Invalid)
6721 return false;
6722
6723 // Deleting a null pointer would have no effect, but it's not permitted by
6724 // std::allocator<T>::deallocate's contract.
6725 if (Pointer.isNullPointer()) {
6726 Info.CCEDiag(E->getExprLoc(), diag::note_constexpr_deallocate_null);
6727 return true;
6728 }
6729
6730 if (!CheckDeleteKind(Info, E, Pointer, DynAlloc::StdAllocator))
6731 return false;
6732
6733 Info.HeapAllocs.erase(Pointer.Base.get<DynamicAllocLValue>());
6734 return true;
6735 }
6736
6737 //===----------------------------------------------------------------------===//
6738 // Generic Evaluation
6739 //===----------------------------------------------------------------------===//
6740 namespace {
6741
6742 class BitCastBuffer {
6743 // FIXME: We're going to need bit-level granularity when we support
6744 // bit-fields.
6745 // FIXME: Its possible under the C++ standard for 'char' to not be 8 bits, but
6746 // we don't support a host or target where that is the case. Still, we should
6747 // use a more generic type in case we ever do.
6748 SmallVector<Optional<unsigned char>, 32> Bytes;
6749
6750 static_assert(std::numeric_limits<unsigned char>::digits >= 8,
6751 "Need at least 8 bit unsigned char");
6752
6753 bool TargetIsLittleEndian;
6754
6755 public:
BitCastBuffer(CharUnits Width,bool TargetIsLittleEndian)6756 BitCastBuffer(CharUnits Width, bool TargetIsLittleEndian)
6757 : Bytes(Width.getQuantity()),
6758 TargetIsLittleEndian(TargetIsLittleEndian) {}
6759
6760 LLVM_NODISCARD
readObject(CharUnits Offset,CharUnits Width,SmallVectorImpl<unsigned char> & Output) const6761 bool readObject(CharUnits Offset, CharUnits Width,
6762 SmallVectorImpl<unsigned char> &Output) const {
6763 for (CharUnits I = Offset, E = Offset + Width; I != E; ++I) {
6764 // If a byte of an integer is uninitialized, then the whole integer is
6765 // uninitialized.
6766 if (!Bytes[I.getQuantity()])
6767 return false;
6768 Output.push_back(*Bytes[I.getQuantity()]);
6769 }
6770 if (llvm::sys::IsLittleEndianHost != TargetIsLittleEndian)
6771 std::reverse(Output.begin(), Output.end());
6772 return true;
6773 }
6774
writeObject(CharUnits Offset,SmallVectorImpl<unsigned char> & Input)6775 void writeObject(CharUnits Offset, SmallVectorImpl<unsigned char> &Input) {
6776 if (llvm::sys::IsLittleEndianHost != TargetIsLittleEndian)
6777 std::reverse(Input.begin(), Input.end());
6778
6779 size_t Index = 0;
6780 for (unsigned char Byte : Input) {
6781 assert(!Bytes[Offset.getQuantity() + Index] && "overwriting a byte?");
6782 Bytes[Offset.getQuantity() + Index] = Byte;
6783 ++Index;
6784 }
6785 }
6786
size()6787 size_t size() { return Bytes.size(); }
6788 };
6789
6790 /// Traverse an APValue to produce an BitCastBuffer, emulating how the current
6791 /// target would represent the value at runtime.
6792 class APValueToBufferConverter {
6793 EvalInfo &Info;
6794 BitCastBuffer Buffer;
6795 const CastExpr *BCE;
6796
APValueToBufferConverter(EvalInfo & Info,CharUnits ObjectWidth,const CastExpr * BCE)6797 APValueToBufferConverter(EvalInfo &Info, CharUnits ObjectWidth,
6798 const CastExpr *BCE)
6799 : Info(Info),
6800 Buffer(ObjectWidth, Info.Ctx.getTargetInfo().isLittleEndian()),
6801 BCE(BCE) {}
6802
visit(const APValue & Val,QualType Ty)6803 bool visit(const APValue &Val, QualType Ty) {
6804 return visit(Val, Ty, CharUnits::fromQuantity(0));
6805 }
6806
6807 // Write out Val with type Ty into Buffer starting at Offset.
visit(const APValue & Val,QualType Ty,CharUnits Offset)6808 bool visit(const APValue &Val, QualType Ty, CharUnits Offset) {
6809 assert((size_t)Offset.getQuantity() <= Buffer.size());
6810
6811 // As a special case, nullptr_t has an indeterminate value.
6812 if (Ty->isNullPtrType())
6813 return true;
6814
6815 // Dig through Src to find the byte at SrcOffset.
6816 switch (Val.getKind()) {
6817 case APValue::Indeterminate:
6818 case APValue::None:
6819 return true;
6820
6821 case APValue::Int:
6822 return visitInt(Val.getInt(), Ty, Offset);
6823 case APValue::Float:
6824 return visitFloat(Val.getFloat(), Ty, Offset);
6825 case APValue::Array:
6826 return visitArray(Val, Ty, Offset);
6827 case APValue::Struct:
6828 return visitRecord(Val, Ty, Offset);
6829
6830 case APValue::ComplexInt:
6831 case APValue::ComplexFloat:
6832 case APValue::Vector:
6833 case APValue::FixedPoint:
6834 // FIXME: We should support these.
6835
6836 case APValue::Union:
6837 case APValue::MemberPointer:
6838 case APValue::AddrLabelDiff: {
6839 Info.FFDiag(BCE->getBeginLoc(),
6840 diag::note_constexpr_bit_cast_unsupported_type)
6841 << Ty;
6842 return false;
6843 }
6844
6845 case APValue::LValue:
6846 llvm_unreachable("LValue subobject in bit_cast?");
6847 }
6848 llvm_unreachable("Unhandled APValue::ValueKind");
6849 }
6850
visitRecord(const APValue & Val,QualType Ty,CharUnits Offset)6851 bool visitRecord(const APValue &Val, QualType Ty, CharUnits Offset) {
6852 const RecordDecl *RD = Ty->getAsRecordDecl();
6853 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
6854
6855 // Visit the base classes.
6856 if (auto *CXXRD = dyn_cast<CXXRecordDecl>(RD)) {
6857 for (size_t I = 0, E = CXXRD->getNumBases(); I != E; ++I) {
6858 const CXXBaseSpecifier &BS = CXXRD->bases_begin()[I];
6859 CXXRecordDecl *BaseDecl = BS.getType()->getAsCXXRecordDecl();
6860
6861 if (!visitRecord(Val.getStructBase(I), BS.getType(),
6862 Layout.getBaseClassOffset(BaseDecl) + Offset))
6863 return false;
6864 }
6865 }
6866
6867 // Visit the fields.
6868 unsigned FieldIdx = 0;
6869 for (FieldDecl *FD : RD->fields()) {
6870 if (FD->isBitField()) {
6871 Info.FFDiag(BCE->getBeginLoc(),
6872 diag::note_constexpr_bit_cast_unsupported_bitfield);
6873 return false;
6874 }
6875
6876 uint64_t FieldOffsetBits = Layout.getFieldOffset(FieldIdx);
6877
6878 assert(FieldOffsetBits % Info.Ctx.getCharWidth() == 0 &&
6879 "only bit-fields can have sub-char alignment");
6880 CharUnits FieldOffset =
6881 Info.Ctx.toCharUnitsFromBits(FieldOffsetBits) + Offset;
6882 QualType FieldTy = FD->getType();
6883 if (!visit(Val.getStructField(FieldIdx), FieldTy, FieldOffset))
6884 return false;
6885 ++FieldIdx;
6886 }
6887
6888 return true;
6889 }
6890
visitArray(const APValue & Val,QualType Ty,CharUnits Offset)6891 bool visitArray(const APValue &Val, QualType Ty, CharUnits Offset) {
6892 const auto *CAT =
6893 dyn_cast_or_null<ConstantArrayType>(Ty->getAsArrayTypeUnsafe());
6894 if (!CAT)
6895 return false;
6896
6897 CharUnits ElemWidth = Info.Ctx.getTypeSizeInChars(CAT->getElementType());
6898 unsigned NumInitializedElts = Val.getArrayInitializedElts();
6899 unsigned ArraySize = Val.getArraySize();
6900 // First, initialize the initialized elements.
6901 for (unsigned I = 0; I != NumInitializedElts; ++I) {
6902 const APValue &SubObj = Val.getArrayInitializedElt(I);
6903 if (!visit(SubObj, CAT->getElementType(), Offset + I * ElemWidth))
6904 return false;
6905 }
6906
6907 // Next, initialize the rest of the array using the filler.
6908 if (Val.hasArrayFiller()) {
6909 const APValue &Filler = Val.getArrayFiller();
6910 for (unsigned I = NumInitializedElts; I != ArraySize; ++I) {
6911 if (!visit(Filler, CAT->getElementType(), Offset + I * ElemWidth))
6912 return false;
6913 }
6914 }
6915
6916 return true;
6917 }
6918
visitInt(const APSInt & Val,QualType Ty,CharUnits Offset)6919 bool visitInt(const APSInt &Val, QualType Ty, CharUnits Offset) {
6920 APSInt AdjustedVal = Val;
6921 unsigned Width = AdjustedVal.getBitWidth();
6922 if (Ty->isBooleanType()) {
6923 Width = Info.Ctx.getTypeSize(Ty);
6924 AdjustedVal = AdjustedVal.extend(Width);
6925 }
6926
6927 SmallVector<unsigned char, 8> Bytes(Width / 8);
6928 llvm::StoreIntToMemory(AdjustedVal, &*Bytes.begin(), Width / 8);
6929 Buffer.writeObject(Offset, Bytes);
6930 return true;
6931 }
6932
visitFloat(const APFloat & Val,QualType Ty,CharUnits Offset)6933 bool visitFloat(const APFloat &Val, QualType Ty, CharUnits Offset) {
6934 APSInt AsInt(Val.bitcastToAPInt());
6935 return visitInt(AsInt, Ty, Offset);
6936 }
6937
6938 public:
convert(EvalInfo & Info,const APValue & Src,const CastExpr * BCE)6939 static Optional<BitCastBuffer> convert(EvalInfo &Info, const APValue &Src,
6940 const CastExpr *BCE) {
6941 CharUnits DstSize = Info.Ctx.getTypeSizeInChars(BCE->getType());
6942 APValueToBufferConverter Converter(Info, DstSize, BCE);
6943 if (!Converter.visit(Src, BCE->getSubExpr()->getType()))
6944 return None;
6945 return Converter.Buffer;
6946 }
6947 };
6948
6949 /// Write an BitCastBuffer into an APValue.
6950 class BufferToAPValueConverter {
6951 EvalInfo &Info;
6952 const BitCastBuffer &Buffer;
6953 const CastExpr *BCE;
6954
BufferToAPValueConverter(EvalInfo & Info,const BitCastBuffer & Buffer,const CastExpr * BCE)6955 BufferToAPValueConverter(EvalInfo &Info, const BitCastBuffer &Buffer,
6956 const CastExpr *BCE)
6957 : Info(Info), Buffer(Buffer), BCE(BCE) {}
6958
6959 // Emit an unsupported bit_cast type error. Sema refuses to build a bit_cast
6960 // with an invalid type, so anything left is a deficiency on our part (FIXME).
6961 // Ideally this will be unreachable.
unsupportedType(QualType Ty)6962 llvm::NoneType unsupportedType(QualType Ty) {
6963 Info.FFDiag(BCE->getBeginLoc(),
6964 diag::note_constexpr_bit_cast_unsupported_type)
6965 << Ty;
6966 return None;
6967 }
6968
unrepresentableValue(QualType Ty,const APSInt & Val)6969 llvm::NoneType unrepresentableValue(QualType Ty, const APSInt &Val) {
6970 Info.FFDiag(BCE->getBeginLoc(),
6971 diag::note_constexpr_bit_cast_unrepresentable_value)
6972 << Ty << toString(Val, /*Radix=*/10);
6973 return None;
6974 }
6975
visit(const BuiltinType * T,CharUnits Offset,const EnumType * EnumSugar=nullptr)6976 Optional<APValue> visit(const BuiltinType *T, CharUnits Offset,
6977 const EnumType *EnumSugar = nullptr) {
6978 if (T->isNullPtrType()) {
6979 uint64_t NullValue = Info.Ctx.getTargetNullPointerValue(QualType(T, 0));
6980 return APValue((Expr *)nullptr,
6981 /*Offset=*/CharUnits::fromQuantity(NullValue),
6982 APValue::NoLValuePath{}, /*IsNullPtr=*/true);
6983 }
6984
6985 CharUnits SizeOf = Info.Ctx.getTypeSizeInChars(T);
6986
6987 // Work around floating point types that contain unused padding bytes. This
6988 // is really just `long double` on x86, which is the only fundamental type
6989 // with padding bytes.
6990 if (T->isRealFloatingType()) {
6991 const llvm::fltSemantics &Semantics =
6992 Info.Ctx.getFloatTypeSemantics(QualType(T, 0));
6993 unsigned NumBits = llvm::APFloatBase::getSizeInBits(Semantics);
6994 assert(NumBits % 8 == 0);
6995 CharUnits NumBytes = CharUnits::fromQuantity(NumBits / 8);
6996 if (NumBytes != SizeOf)
6997 SizeOf = NumBytes;
6998 }
6999
7000 SmallVector<uint8_t, 8> Bytes;
7001 if (!Buffer.readObject(Offset, SizeOf, Bytes)) {
7002 // If this is std::byte or unsigned char, then its okay to store an
7003 // indeterminate value.
7004 bool IsStdByte = EnumSugar && EnumSugar->isStdByteType();
7005 bool IsUChar =
7006 !EnumSugar && (T->isSpecificBuiltinType(BuiltinType::UChar) ||
7007 T->isSpecificBuiltinType(BuiltinType::Char_U));
7008 if (!IsStdByte && !IsUChar) {
7009 QualType DisplayType(EnumSugar ? (const Type *)EnumSugar : T, 0);
7010 Info.FFDiag(BCE->getExprLoc(),
7011 diag::note_constexpr_bit_cast_indet_dest)
7012 << DisplayType << Info.Ctx.getLangOpts().CharIsSigned;
7013 return None;
7014 }
7015
7016 return APValue::IndeterminateValue();
7017 }
7018
7019 APSInt Val(SizeOf.getQuantity() * Info.Ctx.getCharWidth(), true);
7020 llvm::LoadIntFromMemory(Val, &*Bytes.begin(), Bytes.size());
7021
7022 if (T->isIntegralOrEnumerationType()) {
7023 Val.setIsSigned(T->isSignedIntegerOrEnumerationType());
7024
7025 unsigned IntWidth = Info.Ctx.getIntWidth(QualType(T, 0));
7026 if (IntWidth != Val.getBitWidth()) {
7027 APSInt Truncated = Val.trunc(IntWidth);
7028 if (Truncated.extend(Val.getBitWidth()) != Val)
7029 return unrepresentableValue(QualType(T, 0), Val);
7030 Val = Truncated;
7031 }
7032
7033 return APValue(Val);
7034 }
7035
7036 if (T->isRealFloatingType()) {
7037 const llvm::fltSemantics &Semantics =
7038 Info.Ctx.getFloatTypeSemantics(QualType(T, 0));
7039 return APValue(APFloat(Semantics, Val));
7040 }
7041
7042 return unsupportedType(QualType(T, 0));
7043 }
7044
visit(const RecordType * RTy,CharUnits Offset)7045 Optional<APValue> visit(const RecordType *RTy, CharUnits Offset) {
7046 const RecordDecl *RD = RTy->getAsRecordDecl();
7047 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
7048
7049 unsigned NumBases = 0;
7050 if (auto *CXXRD = dyn_cast<CXXRecordDecl>(RD))
7051 NumBases = CXXRD->getNumBases();
7052
7053 APValue ResultVal(APValue::UninitStruct(), NumBases,
7054 std::distance(RD->field_begin(), RD->field_end()));
7055
7056 // Visit the base classes.
7057 if (auto *CXXRD = dyn_cast<CXXRecordDecl>(RD)) {
7058 for (size_t I = 0, E = CXXRD->getNumBases(); I != E; ++I) {
7059 const CXXBaseSpecifier &BS = CXXRD->bases_begin()[I];
7060 CXXRecordDecl *BaseDecl = BS.getType()->getAsCXXRecordDecl();
7061 if (BaseDecl->isEmpty() ||
7062 Info.Ctx.getASTRecordLayout(BaseDecl).getNonVirtualSize().isZero())
7063 continue;
7064
7065 Optional<APValue> SubObj = visitType(
7066 BS.getType(), Layout.getBaseClassOffset(BaseDecl) + Offset);
7067 if (!SubObj)
7068 return None;
7069 ResultVal.getStructBase(I) = *SubObj;
7070 }
7071 }
7072
7073 // Visit the fields.
7074 unsigned FieldIdx = 0;
7075 for (FieldDecl *FD : RD->fields()) {
7076 // FIXME: We don't currently support bit-fields. A lot of the logic for
7077 // this is in CodeGen, so we need to factor it around.
7078 if (FD->isBitField()) {
7079 Info.FFDiag(BCE->getBeginLoc(),
7080 diag::note_constexpr_bit_cast_unsupported_bitfield);
7081 return None;
7082 }
7083
7084 uint64_t FieldOffsetBits = Layout.getFieldOffset(FieldIdx);
7085 assert(FieldOffsetBits % Info.Ctx.getCharWidth() == 0);
7086
7087 CharUnits FieldOffset =
7088 CharUnits::fromQuantity(FieldOffsetBits / Info.Ctx.getCharWidth()) +
7089 Offset;
7090 QualType FieldTy = FD->getType();
7091 Optional<APValue> SubObj = visitType(FieldTy, FieldOffset);
7092 if (!SubObj)
7093 return None;
7094 ResultVal.getStructField(FieldIdx) = *SubObj;
7095 ++FieldIdx;
7096 }
7097
7098 return ResultVal;
7099 }
7100
visit(const EnumType * Ty,CharUnits Offset)7101 Optional<APValue> visit(const EnumType *Ty, CharUnits Offset) {
7102 QualType RepresentationType = Ty->getDecl()->getIntegerType();
7103 assert(!RepresentationType.isNull() &&
7104 "enum forward decl should be caught by Sema");
7105 const auto *AsBuiltin =
7106 RepresentationType.getCanonicalType()->castAs<BuiltinType>();
7107 // Recurse into the underlying type. Treat std::byte transparently as
7108 // unsigned char.
7109 return visit(AsBuiltin, Offset, /*EnumTy=*/Ty);
7110 }
7111
visit(const ConstantArrayType * Ty,CharUnits Offset)7112 Optional<APValue> visit(const ConstantArrayType *Ty, CharUnits Offset) {
7113 size_t Size = Ty->getSize().getLimitedValue();
7114 CharUnits ElementWidth = Info.Ctx.getTypeSizeInChars(Ty->getElementType());
7115
7116 APValue ArrayValue(APValue::UninitArray(), Size, Size);
7117 for (size_t I = 0; I != Size; ++I) {
7118 Optional<APValue> ElementValue =
7119 visitType(Ty->getElementType(), Offset + I * ElementWidth);
7120 if (!ElementValue)
7121 return None;
7122 ArrayValue.getArrayInitializedElt(I) = std::move(*ElementValue);
7123 }
7124
7125 return ArrayValue;
7126 }
7127
visit(const Type * Ty,CharUnits Offset)7128 Optional<APValue> visit(const Type *Ty, CharUnits Offset) {
7129 return unsupportedType(QualType(Ty, 0));
7130 }
7131
visitType(QualType Ty,CharUnits Offset)7132 Optional<APValue> visitType(QualType Ty, CharUnits Offset) {
7133 QualType Can = Ty.getCanonicalType();
7134
7135 switch (Can->getTypeClass()) {
7136 #define TYPE(Class, Base) \
7137 case Type::Class: \
7138 return visit(cast<Class##Type>(Can.getTypePtr()), Offset);
7139 #define ABSTRACT_TYPE(Class, Base)
7140 #define NON_CANONICAL_TYPE(Class, Base) \
7141 case Type::Class: \
7142 llvm_unreachable("non-canonical type should be impossible!");
7143 #define DEPENDENT_TYPE(Class, Base) \
7144 case Type::Class: \
7145 llvm_unreachable( \
7146 "dependent types aren't supported in the constant evaluator!");
7147 #define NON_CANONICAL_UNLESS_DEPENDENT(Class, Base) \
7148 case Type::Class: \
7149 llvm_unreachable("either dependent or not canonical!");
7150 #include "clang/AST/TypeNodes.inc"
7151 }
7152 llvm_unreachable("Unhandled Type::TypeClass");
7153 }
7154
7155 public:
7156 // Pull out a full value of type DstType.
convert(EvalInfo & Info,BitCastBuffer & Buffer,const CastExpr * BCE)7157 static Optional<APValue> convert(EvalInfo &Info, BitCastBuffer &Buffer,
7158 const CastExpr *BCE) {
7159 BufferToAPValueConverter Converter(Info, Buffer, BCE);
7160 return Converter.visitType(BCE->getType(), CharUnits::fromQuantity(0));
7161 }
7162 };
7163
checkBitCastConstexprEligibilityType(SourceLocation Loc,QualType Ty,EvalInfo * Info,const ASTContext & Ctx,bool CheckingDest)7164 static bool checkBitCastConstexprEligibilityType(SourceLocation Loc,
7165 QualType Ty, EvalInfo *Info,
7166 const ASTContext &Ctx,
7167 bool CheckingDest) {
7168 Ty = Ty.getCanonicalType();
7169
7170 auto diag = [&](int Reason) {
7171 if (Info)
7172 Info->FFDiag(Loc, diag::note_constexpr_bit_cast_invalid_type)
7173 << CheckingDest << (Reason == 4) << Reason;
7174 return false;
7175 };
7176 auto note = [&](int Construct, QualType NoteTy, SourceLocation NoteLoc) {
7177 if (Info)
7178 Info->Note(NoteLoc, diag::note_constexpr_bit_cast_invalid_subtype)
7179 << NoteTy << Construct << Ty;
7180 return false;
7181 };
7182
7183 if (Ty->isUnionType())
7184 return diag(0);
7185 if (Ty->isPointerType())
7186 return diag(1);
7187 if (Ty->isMemberPointerType())
7188 return diag(2);
7189 if (Ty.isVolatileQualified())
7190 return diag(3);
7191
7192 if (RecordDecl *Record = Ty->getAsRecordDecl()) {
7193 if (auto *CXXRD = dyn_cast<CXXRecordDecl>(Record)) {
7194 for (CXXBaseSpecifier &BS : CXXRD->bases())
7195 if (!checkBitCastConstexprEligibilityType(Loc, BS.getType(), Info, Ctx,
7196 CheckingDest))
7197 return note(1, BS.getType(), BS.getBeginLoc());
7198 }
7199 for (FieldDecl *FD : Record->fields()) {
7200 if (FD->getType()->isReferenceType())
7201 return diag(4);
7202 if (!checkBitCastConstexprEligibilityType(Loc, FD->getType(), Info, Ctx,
7203 CheckingDest))
7204 return note(0, FD->getType(), FD->getBeginLoc());
7205 }
7206 }
7207
7208 if (Ty->isArrayType() &&
7209 !checkBitCastConstexprEligibilityType(Loc, Ctx.getBaseElementType(Ty),
7210 Info, Ctx, CheckingDest))
7211 return false;
7212
7213 return true;
7214 }
7215
checkBitCastConstexprEligibility(EvalInfo * Info,const ASTContext & Ctx,const CastExpr * BCE)7216 static bool checkBitCastConstexprEligibility(EvalInfo *Info,
7217 const ASTContext &Ctx,
7218 const CastExpr *BCE) {
7219 bool DestOK = checkBitCastConstexprEligibilityType(
7220 BCE->getBeginLoc(), BCE->getType(), Info, Ctx, true);
7221 bool SourceOK = DestOK && checkBitCastConstexprEligibilityType(
7222 BCE->getBeginLoc(),
7223 BCE->getSubExpr()->getType(), Info, Ctx, false);
7224 return SourceOK;
7225 }
7226
handleLValueToRValueBitCast(EvalInfo & Info,APValue & DestValue,APValue & SourceValue,const CastExpr * BCE)7227 static bool handleLValueToRValueBitCast(EvalInfo &Info, APValue &DestValue,
7228 APValue &SourceValue,
7229 const CastExpr *BCE) {
7230 assert(CHAR_BIT == 8 && Info.Ctx.getTargetInfo().getCharWidth() == 8 &&
7231 "no host or target supports non 8-bit chars");
7232 assert(SourceValue.isLValue() &&
7233 "LValueToRValueBitcast requires an lvalue operand!");
7234
7235 if (!checkBitCastConstexprEligibility(&Info, Info.Ctx, BCE))
7236 return false;
7237
7238 LValue SourceLValue;
7239 APValue SourceRValue;
7240 SourceLValue.setFrom(Info.Ctx, SourceValue);
7241 if (!handleLValueToRValueConversion(
7242 Info, BCE, BCE->getSubExpr()->getType().withConst(), SourceLValue,
7243 SourceRValue, /*WantObjectRepresentation=*/true))
7244 return false;
7245
7246 // Read out SourceValue into a char buffer.
7247 Optional<BitCastBuffer> Buffer =
7248 APValueToBufferConverter::convert(Info, SourceRValue, BCE);
7249 if (!Buffer)
7250 return false;
7251
7252 // Write out the buffer into a new APValue.
7253 Optional<APValue> MaybeDestValue =
7254 BufferToAPValueConverter::convert(Info, *Buffer, BCE);
7255 if (!MaybeDestValue)
7256 return false;
7257
7258 DestValue = std::move(*MaybeDestValue);
7259 return true;
7260 }
7261
7262 template <class Derived>
7263 class ExprEvaluatorBase
7264 : public ConstStmtVisitor<Derived, bool> {
7265 private:
getDerived()7266 Derived &getDerived() { return static_cast<Derived&>(*this); }
DerivedSuccess(const APValue & V,const Expr * E)7267 bool DerivedSuccess(const APValue &V, const Expr *E) {
7268 return getDerived().Success(V, E);
7269 }
DerivedZeroInitialization(const Expr * E)7270 bool DerivedZeroInitialization(const Expr *E) {
7271 return getDerived().ZeroInitialization(E);
7272 }
7273
7274 // Check whether a conditional operator with a non-constant condition is a
7275 // potential constant expression. If neither arm is a potential constant
7276 // expression, then the conditional operator is not either.
7277 template<typename ConditionalOperator>
CheckPotentialConstantConditional(const ConditionalOperator * E)7278 void CheckPotentialConstantConditional(const ConditionalOperator *E) {
7279 assert(Info.checkingPotentialConstantExpression());
7280
7281 // Speculatively evaluate both arms.
7282 SmallVector<PartialDiagnosticAt, 8> Diag;
7283 {
7284 SpeculativeEvaluationRAII Speculate(Info, &Diag);
7285 StmtVisitorTy::Visit(E->getFalseExpr());
7286 if (Diag.empty())
7287 return;
7288 }
7289
7290 {
7291 SpeculativeEvaluationRAII Speculate(Info, &Diag);
7292 Diag.clear();
7293 StmtVisitorTy::Visit(E->getTrueExpr());
7294 if (Diag.empty())
7295 return;
7296 }
7297
7298 Error(E, diag::note_constexpr_conditional_never_const);
7299 }
7300
7301
7302 template<typename ConditionalOperator>
HandleConditionalOperator(const ConditionalOperator * E)7303 bool HandleConditionalOperator(const ConditionalOperator *E) {
7304 bool BoolResult;
7305 if (!EvaluateAsBooleanCondition(E->getCond(), BoolResult, Info)) {
7306 if (Info.checkingPotentialConstantExpression() && Info.noteFailure()) {
7307 CheckPotentialConstantConditional(E);
7308 return false;
7309 }
7310 if (Info.noteFailure()) {
7311 StmtVisitorTy::Visit(E->getTrueExpr());
7312 StmtVisitorTy::Visit(E->getFalseExpr());
7313 }
7314 return false;
7315 }
7316
7317 Expr *EvalExpr = BoolResult ? E->getTrueExpr() : E->getFalseExpr();
7318 return StmtVisitorTy::Visit(EvalExpr);
7319 }
7320
7321 protected:
7322 EvalInfo &Info;
7323 typedef ConstStmtVisitor<Derived, bool> StmtVisitorTy;
7324 typedef ExprEvaluatorBase ExprEvaluatorBaseTy;
7325
CCEDiag(const Expr * E,diag::kind D)7326 OptionalDiagnostic CCEDiag(const Expr *E, diag::kind D) {
7327 return Info.CCEDiag(E, D);
7328 }
7329
ZeroInitialization(const Expr * E)7330 bool ZeroInitialization(const Expr *E) { return Error(E); }
7331
7332 public:
ExprEvaluatorBase(EvalInfo & Info)7333 ExprEvaluatorBase(EvalInfo &Info) : Info(Info) {}
7334
getEvalInfo()7335 EvalInfo &getEvalInfo() { return Info; }
7336
7337 /// Report an evaluation error. This should only be called when an error is
7338 /// first discovered. When propagating an error, just return false.
Error(const Expr * E,diag::kind D)7339 bool Error(const Expr *E, diag::kind D) {
7340 Info.FFDiag(E, D);
7341 return false;
7342 }
Error(const Expr * E)7343 bool Error(const Expr *E) {
7344 return Error(E, diag::note_invalid_subexpr_in_const_expr);
7345 }
7346
VisitStmt(const Stmt *)7347 bool VisitStmt(const Stmt *) {
7348 llvm_unreachable("Expression evaluator should not be called on stmts");
7349 }
VisitExpr(const Expr * E)7350 bool VisitExpr(const Expr *E) {
7351 return Error(E);
7352 }
7353
VisitConstantExpr(const ConstantExpr * E)7354 bool VisitConstantExpr(const ConstantExpr *E) {
7355 if (E->hasAPValueResult())
7356 return DerivedSuccess(E->getAPValueResult(), E);
7357
7358 return StmtVisitorTy::Visit(E->getSubExpr());
7359 }
7360
VisitParenExpr(const ParenExpr * E)7361 bool VisitParenExpr(const ParenExpr *E)
7362 { return StmtVisitorTy::Visit(E->getSubExpr()); }
VisitUnaryExtension(const UnaryOperator * E)7363 bool VisitUnaryExtension(const UnaryOperator *E)
7364 { return StmtVisitorTy::Visit(E->getSubExpr()); }
VisitUnaryPlus(const UnaryOperator * E)7365 bool VisitUnaryPlus(const UnaryOperator *E)
7366 { return StmtVisitorTy::Visit(E->getSubExpr()); }
VisitChooseExpr(const ChooseExpr * E)7367 bool VisitChooseExpr(const ChooseExpr *E)
7368 { return StmtVisitorTy::Visit(E->getChosenSubExpr()); }
VisitGenericSelectionExpr(const GenericSelectionExpr * E)7369 bool VisitGenericSelectionExpr(const GenericSelectionExpr *E)
7370 { return StmtVisitorTy::Visit(E->getResultExpr()); }
VisitSubstNonTypeTemplateParmExpr(const SubstNonTypeTemplateParmExpr * E)7371 bool VisitSubstNonTypeTemplateParmExpr(const SubstNonTypeTemplateParmExpr *E)
7372 { return StmtVisitorTy::Visit(E->getReplacement()); }
VisitCXXDefaultArgExpr(const CXXDefaultArgExpr * E)7373 bool VisitCXXDefaultArgExpr(const CXXDefaultArgExpr *E) {
7374 TempVersionRAII RAII(*Info.CurrentCall);
7375 SourceLocExprScopeGuard Guard(E, Info.CurrentCall->CurSourceLocExprScope);
7376 return StmtVisitorTy::Visit(E->getExpr());
7377 }
VisitCXXDefaultInitExpr(const CXXDefaultInitExpr * E)7378 bool VisitCXXDefaultInitExpr(const CXXDefaultInitExpr *E) {
7379 TempVersionRAII RAII(*Info.CurrentCall);
7380 // The initializer may not have been parsed yet, or might be erroneous.
7381 if (!E->getExpr())
7382 return Error(E);
7383 SourceLocExprScopeGuard Guard(E, Info.CurrentCall->CurSourceLocExprScope);
7384 return StmtVisitorTy::Visit(E->getExpr());
7385 }
7386
VisitExprWithCleanups(const ExprWithCleanups * E)7387 bool VisitExprWithCleanups(const ExprWithCleanups *E) {
7388 FullExpressionRAII Scope(Info);
7389 return StmtVisitorTy::Visit(E->getSubExpr()) && Scope.destroy();
7390 }
7391
7392 // Temporaries are registered when created, so we don't care about
7393 // CXXBindTemporaryExpr.
VisitCXXBindTemporaryExpr(const CXXBindTemporaryExpr * E)7394 bool VisitCXXBindTemporaryExpr(const CXXBindTemporaryExpr *E) {
7395 return StmtVisitorTy::Visit(E->getSubExpr());
7396 }
7397
VisitCXXReinterpretCastExpr(const CXXReinterpretCastExpr * E)7398 bool VisitCXXReinterpretCastExpr(const CXXReinterpretCastExpr *E) {
7399 CCEDiag(E, diag::note_constexpr_invalid_cast) << 0;
7400 return static_cast<Derived*>(this)->VisitCastExpr(E);
7401 }
VisitCXXDynamicCastExpr(const CXXDynamicCastExpr * E)7402 bool VisitCXXDynamicCastExpr(const CXXDynamicCastExpr *E) {
7403 if (!Info.Ctx.getLangOpts().CPlusPlus20)
7404 CCEDiag(E, diag::note_constexpr_invalid_cast) << 1;
7405 return static_cast<Derived*>(this)->VisitCastExpr(E);
7406 }
VisitBuiltinBitCastExpr(const BuiltinBitCastExpr * E)7407 bool VisitBuiltinBitCastExpr(const BuiltinBitCastExpr *E) {
7408 return static_cast<Derived*>(this)->VisitCastExpr(E);
7409 }
7410
VisitBinaryOperator(const BinaryOperator * E)7411 bool VisitBinaryOperator(const BinaryOperator *E) {
7412 switch (E->getOpcode()) {
7413 default:
7414 return Error(E);
7415
7416 case BO_Comma:
7417 VisitIgnoredValue(E->getLHS());
7418 return StmtVisitorTy::Visit(E->getRHS());
7419
7420 case BO_PtrMemD:
7421 case BO_PtrMemI: {
7422 LValue Obj;
7423 if (!HandleMemberPointerAccess(Info, E, Obj))
7424 return false;
7425 APValue Result;
7426 if (!handleLValueToRValueConversion(Info, E, E->getType(), Obj, Result))
7427 return false;
7428 return DerivedSuccess(Result, E);
7429 }
7430 }
7431 }
7432
VisitCXXRewrittenBinaryOperator(const CXXRewrittenBinaryOperator * E)7433 bool VisitCXXRewrittenBinaryOperator(const CXXRewrittenBinaryOperator *E) {
7434 return StmtVisitorTy::Visit(E->getSemanticForm());
7435 }
7436
VisitBinaryConditionalOperator(const BinaryConditionalOperator * E)7437 bool VisitBinaryConditionalOperator(const BinaryConditionalOperator *E) {
7438 // Evaluate and cache the common expression. We treat it as a temporary,
7439 // even though it's not quite the same thing.
7440 LValue CommonLV;
7441 if (!Evaluate(Info.CurrentCall->createTemporary(
7442 E->getOpaqueValue(),
7443 getStorageType(Info.Ctx, E->getOpaqueValue()),
7444 ScopeKind::FullExpression, CommonLV),
7445 Info, E->getCommon()))
7446 return false;
7447
7448 return HandleConditionalOperator(E);
7449 }
7450
VisitConditionalOperator(const ConditionalOperator * E)7451 bool VisitConditionalOperator(const ConditionalOperator *E) {
7452 bool IsBcpCall = false;
7453 // If the condition (ignoring parens) is a __builtin_constant_p call,
7454 // the result is a constant expression if it can be folded without
7455 // side-effects. This is an important GNU extension. See GCC PR38377
7456 // for discussion.
7457 if (const CallExpr *CallCE =
7458 dyn_cast<CallExpr>(E->getCond()->IgnoreParenCasts()))
7459 if (CallCE->getBuiltinCallee() == Builtin::BI__builtin_constant_p)
7460 IsBcpCall = true;
7461
7462 // Always assume __builtin_constant_p(...) ? ... : ... is a potential
7463 // constant expression; we can't check whether it's potentially foldable.
7464 // FIXME: We should instead treat __builtin_constant_p as non-constant if
7465 // it would return 'false' in this mode.
7466 if (Info.checkingPotentialConstantExpression() && IsBcpCall)
7467 return false;
7468
7469 FoldConstant Fold(Info, IsBcpCall);
7470 if (!HandleConditionalOperator(E)) {
7471 Fold.keepDiagnostics();
7472 return false;
7473 }
7474
7475 return true;
7476 }
7477
VisitOpaqueValueExpr(const OpaqueValueExpr * E)7478 bool VisitOpaqueValueExpr(const OpaqueValueExpr *E) {
7479 if (APValue *Value = Info.CurrentCall->getCurrentTemporary(E))
7480 return DerivedSuccess(*Value, E);
7481
7482 const Expr *Source = E->getSourceExpr();
7483 if (!Source)
7484 return Error(E);
7485 if (Source == E) { // sanity checking.
7486 assert(0 && "OpaqueValueExpr recursively refers to itself");
7487 return Error(E);
7488 }
7489 return StmtVisitorTy::Visit(Source);
7490 }
7491
VisitPseudoObjectExpr(const PseudoObjectExpr * E)7492 bool VisitPseudoObjectExpr(const PseudoObjectExpr *E) {
7493 for (const Expr *SemE : E->semantics()) {
7494 if (auto *OVE = dyn_cast<OpaqueValueExpr>(SemE)) {
7495 // FIXME: We can't handle the case where an OpaqueValueExpr is also the
7496 // result expression: there could be two different LValues that would
7497 // refer to the same object in that case, and we can't model that.
7498 if (SemE == E->getResultExpr())
7499 return Error(E);
7500
7501 // Unique OVEs get evaluated if and when we encounter them when
7502 // emitting the rest of the semantic form, rather than eagerly.
7503 if (OVE->isUnique())
7504 continue;
7505
7506 LValue LV;
7507 if (!Evaluate(Info.CurrentCall->createTemporary(
7508 OVE, getStorageType(Info.Ctx, OVE),
7509 ScopeKind::FullExpression, LV),
7510 Info, OVE->getSourceExpr()))
7511 return false;
7512 } else if (SemE == E->getResultExpr()) {
7513 if (!StmtVisitorTy::Visit(SemE))
7514 return false;
7515 } else {
7516 if (!EvaluateIgnoredValue(Info, SemE))
7517 return false;
7518 }
7519 }
7520 return true;
7521 }
7522
VisitCallExpr(const CallExpr * E)7523 bool VisitCallExpr(const CallExpr *E) {
7524 APValue Result;
7525 if (!handleCallExpr(E, Result, nullptr))
7526 return false;
7527 return DerivedSuccess(Result, E);
7528 }
7529
handleCallExpr(const CallExpr * E,APValue & Result,const LValue * ResultSlot)7530 bool handleCallExpr(const CallExpr *E, APValue &Result,
7531 const LValue *ResultSlot) {
7532 CallScopeRAII CallScope(Info);
7533
7534 const Expr *Callee = E->getCallee()->IgnoreParens();
7535 QualType CalleeType = Callee->getType();
7536
7537 const FunctionDecl *FD = nullptr;
7538 LValue *This = nullptr, ThisVal;
7539 auto Args = llvm::makeArrayRef(E->getArgs(), E->getNumArgs());
7540 bool HasQualifier = false;
7541
7542 CallRef Call;
7543
7544 // Extract function decl and 'this' pointer from the callee.
7545 if (CalleeType->isSpecificBuiltinType(BuiltinType::BoundMember)) {
7546 const CXXMethodDecl *Member = nullptr;
7547 if (const MemberExpr *ME = dyn_cast<MemberExpr>(Callee)) {
7548 // Explicit bound member calls, such as x.f() or p->g();
7549 if (!EvaluateObjectArgument(Info, ME->getBase(), ThisVal))
7550 return false;
7551 Member = dyn_cast<CXXMethodDecl>(ME->getMemberDecl());
7552 if (!Member)
7553 return Error(Callee);
7554 This = &ThisVal;
7555 HasQualifier = ME->hasQualifier();
7556 } else if (const BinaryOperator *BE = dyn_cast<BinaryOperator>(Callee)) {
7557 // Indirect bound member calls ('.*' or '->*').
7558 const ValueDecl *D =
7559 HandleMemberPointerAccess(Info, BE, ThisVal, false);
7560 if (!D)
7561 return false;
7562 Member = dyn_cast<CXXMethodDecl>(D);
7563 if (!Member)
7564 return Error(Callee);
7565 This = &ThisVal;
7566 } else if (const auto *PDE = dyn_cast<CXXPseudoDestructorExpr>(Callee)) {
7567 if (!Info.getLangOpts().CPlusPlus20)
7568 Info.CCEDiag(PDE, diag::note_constexpr_pseudo_destructor);
7569 return EvaluateObjectArgument(Info, PDE->getBase(), ThisVal) &&
7570 HandleDestruction(Info, PDE, ThisVal, PDE->getDestroyedType());
7571 } else
7572 return Error(Callee);
7573 FD = Member;
7574 } else if (CalleeType->isFunctionPointerType()) {
7575 LValue CalleeLV;
7576 if (!EvaluatePointer(Callee, CalleeLV, Info))
7577 return false;
7578
7579 if (!CalleeLV.getLValueOffset().isZero())
7580 return Error(Callee);
7581 FD = dyn_cast_or_null<FunctionDecl>(
7582 CalleeLV.getLValueBase().dyn_cast<const ValueDecl *>());
7583 if (!FD)
7584 return Error(Callee);
7585 // Don't call function pointers which have been cast to some other type.
7586 // Per DR (no number yet), the caller and callee can differ in noexcept.
7587 if (!Info.Ctx.hasSameFunctionTypeIgnoringExceptionSpec(
7588 CalleeType->getPointeeType(), FD->getType())) {
7589 return Error(E);
7590 }
7591
7592 // For an (overloaded) assignment expression, evaluate the RHS before the
7593 // LHS.
7594 auto *OCE = dyn_cast<CXXOperatorCallExpr>(E);
7595 if (OCE && OCE->isAssignmentOp()) {
7596 assert(Args.size() == 2 && "wrong number of arguments in assignment");
7597 Call = Info.CurrentCall->createCall(FD);
7598 if (!EvaluateArgs(isa<CXXMethodDecl>(FD) ? Args.slice(1) : Args, Call,
7599 Info, FD, /*RightToLeft=*/true))
7600 return false;
7601 }
7602
7603 // Overloaded operator calls to member functions are represented as normal
7604 // calls with '*this' as the first argument.
7605 const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD);
7606 if (MD && !MD->isStatic()) {
7607 // FIXME: When selecting an implicit conversion for an overloaded
7608 // operator delete, we sometimes try to evaluate calls to conversion
7609 // operators without a 'this' parameter!
7610 if (Args.empty())
7611 return Error(E);
7612
7613 if (!EvaluateObjectArgument(Info, Args[0], ThisVal))
7614 return false;
7615 This = &ThisVal;
7616 Args = Args.slice(1);
7617 } else if (MD && MD->isLambdaStaticInvoker()) {
7618 // Map the static invoker for the lambda back to the call operator.
7619 // Conveniently, we don't have to slice out the 'this' argument (as is
7620 // being done for the non-static case), since a static member function
7621 // doesn't have an implicit argument passed in.
7622 const CXXRecordDecl *ClosureClass = MD->getParent();
7623 assert(
7624 ClosureClass->captures_begin() == ClosureClass->captures_end() &&
7625 "Number of captures must be zero for conversion to function-ptr");
7626
7627 const CXXMethodDecl *LambdaCallOp =
7628 ClosureClass->getLambdaCallOperator();
7629
7630 // Set 'FD', the function that will be called below, to the call
7631 // operator. If the closure object represents a generic lambda, find
7632 // the corresponding specialization of the call operator.
7633
7634 if (ClosureClass->isGenericLambda()) {
7635 assert(MD->isFunctionTemplateSpecialization() &&
7636 "A generic lambda's static-invoker function must be a "
7637 "template specialization");
7638 const TemplateArgumentList *TAL = MD->getTemplateSpecializationArgs();
7639 FunctionTemplateDecl *CallOpTemplate =
7640 LambdaCallOp->getDescribedFunctionTemplate();
7641 void *InsertPos = nullptr;
7642 FunctionDecl *CorrespondingCallOpSpecialization =
7643 CallOpTemplate->findSpecialization(TAL->asArray(), InsertPos);
7644 assert(CorrespondingCallOpSpecialization &&
7645 "We must always have a function call operator specialization "
7646 "that corresponds to our static invoker specialization");
7647 FD = cast<CXXMethodDecl>(CorrespondingCallOpSpecialization);
7648 } else
7649 FD = LambdaCallOp;
7650 } else if (FD->isReplaceableGlobalAllocationFunction()) {
7651 if (FD->getDeclName().getCXXOverloadedOperator() == OO_New ||
7652 FD->getDeclName().getCXXOverloadedOperator() == OO_Array_New) {
7653 LValue Ptr;
7654 if (!HandleOperatorNewCall(Info, E, Ptr))
7655 return false;
7656 Ptr.moveInto(Result);
7657 return CallScope.destroy();
7658 } else {
7659 return HandleOperatorDeleteCall(Info, E) && CallScope.destroy();
7660 }
7661 }
7662 } else
7663 return Error(E);
7664
7665 // Evaluate the arguments now if we've not already done so.
7666 if (!Call) {
7667 Call = Info.CurrentCall->createCall(FD);
7668 if (!EvaluateArgs(Args, Call, Info, FD))
7669 return false;
7670 }
7671
7672 SmallVector<QualType, 4> CovariantAdjustmentPath;
7673 if (This) {
7674 auto *NamedMember = dyn_cast<CXXMethodDecl>(FD);
7675 if (NamedMember && NamedMember->isVirtual() && !HasQualifier) {
7676 // Perform virtual dispatch, if necessary.
7677 FD = HandleVirtualDispatch(Info, E, *This, NamedMember,
7678 CovariantAdjustmentPath);
7679 if (!FD)
7680 return false;
7681 } else {
7682 // Check that the 'this' pointer points to an object of the right type.
7683 // FIXME: If this is an assignment operator call, we may need to change
7684 // the active union member before we check this.
7685 if (!checkNonVirtualMemberCallThisPointer(Info, E, *This, NamedMember))
7686 return false;
7687 }
7688 }
7689
7690 // Destructor calls are different enough that they have their own codepath.
7691 if (auto *DD = dyn_cast<CXXDestructorDecl>(FD)) {
7692 assert(This && "no 'this' pointer for destructor call");
7693 return HandleDestruction(Info, E, *This,
7694 Info.Ctx.getRecordType(DD->getParent())) &&
7695 CallScope.destroy();
7696 }
7697
7698 const FunctionDecl *Definition = nullptr;
7699 Stmt *Body = FD->getBody(Definition);
7700
7701 if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition, Body) ||
7702 !HandleFunctionCall(E->getExprLoc(), Definition, This, Args, Call,
7703 Body, Info, Result, ResultSlot))
7704 return false;
7705
7706 if (!CovariantAdjustmentPath.empty() &&
7707 !HandleCovariantReturnAdjustment(Info, E, Result,
7708 CovariantAdjustmentPath))
7709 return false;
7710
7711 return CallScope.destroy();
7712 }
7713
VisitCompoundLiteralExpr(const CompoundLiteralExpr * E)7714 bool VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) {
7715 return StmtVisitorTy::Visit(E->getInitializer());
7716 }
VisitInitListExpr(const InitListExpr * E)7717 bool VisitInitListExpr(const InitListExpr *E) {
7718 if (E->getNumInits() == 0)
7719 return DerivedZeroInitialization(E);
7720 if (E->getNumInits() == 1)
7721 return StmtVisitorTy::Visit(E->getInit(0));
7722 return Error(E);
7723 }
VisitImplicitValueInitExpr(const ImplicitValueInitExpr * E)7724 bool VisitImplicitValueInitExpr(const ImplicitValueInitExpr *E) {
7725 return DerivedZeroInitialization(E);
7726 }
VisitCXXScalarValueInitExpr(const CXXScalarValueInitExpr * E)7727 bool VisitCXXScalarValueInitExpr(const CXXScalarValueInitExpr *E) {
7728 return DerivedZeroInitialization(E);
7729 }
VisitCXXNullPtrLiteralExpr(const CXXNullPtrLiteralExpr * E)7730 bool VisitCXXNullPtrLiteralExpr(const CXXNullPtrLiteralExpr *E) {
7731 return DerivedZeroInitialization(E);
7732 }
7733
7734 /// A member expression where the object is a prvalue is itself a prvalue.
VisitMemberExpr(const MemberExpr * E)7735 bool VisitMemberExpr(const MemberExpr *E) {
7736 assert(!Info.Ctx.getLangOpts().CPlusPlus11 &&
7737 "missing temporary materialization conversion");
7738 assert(!E->isArrow() && "missing call to bound member function?");
7739
7740 APValue Val;
7741 if (!Evaluate(Val, Info, E->getBase()))
7742 return false;
7743
7744 QualType BaseTy = E->getBase()->getType();
7745
7746 const FieldDecl *FD = dyn_cast<FieldDecl>(E->getMemberDecl());
7747 if (!FD) return Error(E);
7748 assert(!FD->getType()->isReferenceType() && "prvalue reference?");
7749 assert(BaseTy->castAs<RecordType>()->getDecl()->getCanonicalDecl() ==
7750 FD->getParent()->getCanonicalDecl() && "record / field mismatch");
7751
7752 // Note: there is no lvalue base here. But this case should only ever
7753 // happen in C or in C++98, where we cannot be evaluating a constexpr
7754 // constructor, which is the only case the base matters.
7755 CompleteObject Obj(APValue::LValueBase(), &Val, BaseTy);
7756 SubobjectDesignator Designator(BaseTy);
7757 Designator.addDeclUnchecked(FD);
7758
7759 APValue Result;
7760 return extractSubobject(Info, E, Obj, Designator, Result) &&
7761 DerivedSuccess(Result, E);
7762 }
7763
VisitExtVectorElementExpr(const ExtVectorElementExpr * E)7764 bool VisitExtVectorElementExpr(const ExtVectorElementExpr *E) {
7765 APValue Val;
7766 if (!Evaluate(Val, Info, E->getBase()))
7767 return false;
7768
7769 if (Val.isVector()) {
7770 SmallVector<uint32_t, 4> Indices;
7771 E->getEncodedElementAccess(Indices);
7772 if (Indices.size() == 1) {
7773 // Return scalar.
7774 return DerivedSuccess(Val.getVectorElt(Indices[0]), E);
7775 } else {
7776 // Construct new APValue vector.
7777 SmallVector<APValue, 4> Elts;
7778 for (unsigned I = 0; I < Indices.size(); ++I) {
7779 Elts.push_back(Val.getVectorElt(Indices[I]));
7780 }
7781 APValue VecResult(Elts.data(), Indices.size());
7782 return DerivedSuccess(VecResult, E);
7783 }
7784 }
7785
7786 return false;
7787 }
7788
VisitCastExpr(const CastExpr * E)7789 bool VisitCastExpr(const CastExpr *E) {
7790 switch (E->getCastKind()) {
7791 default:
7792 break;
7793
7794 case CK_AtomicToNonAtomic: {
7795 APValue AtomicVal;
7796 // This does not need to be done in place even for class/array types:
7797 // atomic-to-non-atomic conversion implies copying the object
7798 // representation.
7799 if (!Evaluate(AtomicVal, Info, E->getSubExpr()))
7800 return false;
7801 return DerivedSuccess(AtomicVal, E);
7802 }
7803
7804 case CK_NoOp:
7805 case CK_UserDefinedConversion:
7806 return StmtVisitorTy::Visit(E->getSubExpr());
7807
7808 case CK_LValueToRValue: {
7809 LValue LVal;
7810 if (!EvaluateLValue(E->getSubExpr(), LVal, Info))
7811 return false;
7812 APValue RVal;
7813 // Note, we use the subexpression's type in order to retain cv-qualifiers.
7814 if (!handleLValueToRValueConversion(Info, E, E->getSubExpr()->getType(),
7815 LVal, RVal))
7816 return false;
7817 return DerivedSuccess(RVal, E);
7818 }
7819 case CK_LValueToRValueBitCast: {
7820 APValue DestValue, SourceValue;
7821 if (!Evaluate(SourceValue, Info, E->getSubExpr()))
7822 return false;
7823 if (!handleLValueToRValueBitCast(Info, DestValue, SourceValue, E))
7824 return false;
7825 return DerivedSuccess(DestValue, E);
7826 }
7827
7828 case CK_AddressSpaceConversion: {
7829 APValue Value;
7830 if (!Evaluate(Value, Info, E->getSubExpr()))
7831 return false;
7832 return DerivedSuccess(Value, E);
7833 }
7834 }
7835
7836 return Error(E);
7837 }
7838
VisitUnaryPostInc(const UnaryOperator * UO)7839 bool VisitUnaryPostInc(const UnaryOperator *UO) {
7840 return VisitUnaryPostIncDec(UO);
7841 }
VisitUnaryPostDec(const UnaryOperator * UO)7842 bool VisitUnaryPostDec(const UnaryOperator *UO) {
7843 return VisitUnaryPostIncDec(UO);
7844 }
VisitUnaryPostIncDec(const UnaryOperator * UO)7845 bool VisitUnaryPostIncDec(const UnaryOperator *UO) {
7846 if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure())
7847 return Error(UO);
7848
7849 LValue LVal;
7850 if (!EvaluateLValue(UO->getSubExpr(), LVal, Info))
7851 return false;
7852 APValue RVal;
7853 if (!handleIncDec(this->Info, UO, LVal, UO->getSubExpr()->getType(),
7854 UO->isIncrementOp(), &RVal))
7855 return false;
7856 return DerivedSuccess(RVal, UO);
7857 }
7858
VisitStmtExpr(const StmtExpr * E)7859 bool VisitStmtExpr(const StmtExpr *E) {
7860 // We will have checked the full-expressions inside the statement expression
7861 // when they were completed, and don't need to check them again now.
7862 llvm::SaveAndRestore<bool> NotCheckingForUB(
7863 Info.CheckingForUndefinedBehavior, false);
7864
7865 const CompoundStmt *CS = E->getSubStmt();
7866 if (CS->body_empty())
7867 return true;
7868
7869 BlockScopeRAII Scope(Info);
7870 for (CompoundStmt::const_body_iterator BI = CS->body_begin(),
7871 BE = CS->body_end();
7872 /**/; ++BI) {
7873 if (BI + 1 == BE) {
7874 const Expr *FinalExpr = dyn_cast<Expr>(*BI);
7875 if (!FinalExpr) {
7876 Info.FFDiag((*BI)->getBeginLoc(),
7877 diag::note_constexpr_stmt_expr_unsupported);
7878 return false;
7879 }
7880 return this->Visit(FinalExpr) && Scope.destroy();
7881 }
7882
7883 APValue ReturnValue;
7884 StmtResult Result = { ReturnValue, nullptr };
7885 EvalStmtResult ESR = EvaluateStmt(Result, Info, *BI);
7886 if (ESR != ESR_Succeeded) {
7887 // FIXME: If the statement-expression terminated due to 'return',
7888 // 'break', or 'continue', it would be nice to propagate that to
7889 // the outer statement evaluation rather than bailing out.
7890 if (ESR != ESR_Failed)
7891 Info.FFDiag((*BI)->getBeginLoc(),
7892 diag::note_constexpr_stmt_expr_unsupported);
7893 return false;
7894 }
7895 }
7896
7897 llvm_unreachable("Return from function from the loop above.");
7898 }
7899
7900 /// Visit a value which is evaluated, but whose value is ignored.
VisitIgnoredValue(const Expr * E)7901 void VisitIgnoredValue(const Expr *E) {
7902 EvaluateIgnoredValue(Info, E);
7903 }
7904
7905 /// Potentially visit a MemberExpr's base expression.
VisitIgnoredBaseExpression(const Expr * E)7906 void VisitIgnoredBaseExpression(const Expr *E) {
7907 // While MSVC doesn't evaluate the base expression, it does diagnose the
7908 // presence of side-effecting behavior.
7909 if (Info.getLangOpts().MSVCCompat && !E->HasSideEffects(Info.Ctx))
7910 return;
7911 VisitIgnoredValue(E);
7912 }
7913 };
7914
7915 } // namespace
7916
7917 //===----------------------------------------------------------------------===//
7918 // Common base class for lvalue and temporary evaluation.
7919 //===----------------------------------------------------------------------===//
7920 namespace {
7921 template<class Derived>
7922 class LValueExprEvaluatorBase
7923 : public ExprEvaluatorBase<Derived> {
7924 protected:
7925 LValue &Result;
7926 bool InvalidBaseOK;
7927 typedef LValueExprEvaluatorBase LValueExprEvaluatorBaseTy;
7928 typedef ExprEvaluatorBase<Derived> ExprEvaluatorBaseTy;
7929
Success(APValue::LValueBase B)7930 bool Success(APValue::LValueBase B) {
7931 Result.set(B);
7932 return true;
7933 }
7934
evaluatePointer(const Expr * E,LValue & Result)7935 bool evaluatePointer(const Expr *E, LValue &Result) {
7936 return EvaluatePointer(E, Result, this->Info, InvalidBaseOK);
7937 }
7938
7939 public:
LValueExprEvaluatorBase(EvalInfo & Info,LValue & Result,bool InvalidBaseOK)7940 LValueExprEvaluatorBase(EvalInfo &Info, LValue &Result, bool InvalidBaseOK)
7941 : ExprEvaluatorBaseTy(Info), Result(Result),
7942 InvalidBaseOK(InvalidBaseOK) {}
7943
Success(const APValue & V,const Expr * E)7944 bool Success(const APValue &V, const Expr *E) {
7945 Result.setFrom(this->Info.Ctx, V);
7946 return true;
7947 }
7948
VisitMemberExpr(const MemberExpr * E)7949 bool VisitMemberExpr(const MemberExpr *E) {
7950 // Handle non-static data members.
7951 QualType BaseTy;
7952 bool EvalOK;
7953 if (E->isArrow()) {
7954 EvalOK = evaluatePointer(E->getBase(), Result);
7955 BaseTy = E->getBase()->getType()->castAs<PointerType>()->getPointeeType();
7956 } else if (E->getBase()->isPRValue()) {
7957 assert(E->getBase()->getType()->isRecordType());
7958 EvalOK = EvaluateTemporary(E->getBase(), Result, this->Info);
7959 BaseTy = E->getBase()->getType();
7960 } else {
7961 EvalOK = this->Visit(E->getBase());
7962 BaseTy = E->getBase()->getType();
7963 }
7964 if (!EvalOK) {
7965 if (!InvalidBaseOK)
7966 return false;
7967 Result.setInvalid(E);
7968 return true;
7969 }
7970
7971 const ValueDecl *MD = E->getMemberDecl();
7972 if (const FieldDecl *FD = dyn_cast<FieldDecl>(E->getMemberDecl())) {
7973 assert(BaseTy->castAs<RecordType>()->getDecl()->getCanonicalDecl() ==
7974 FD->getParent()->getCanonicalDecl() && "record / field mismatch");
7975 (void)BaseTy;
7976 if (!HandleLValueMember(this->Info, E, Result, FD))
7977 return false;
7978 } else if (const IndirectFieldDecl *IFD = dyn_cast<IndirectFieldDecl>(MD)) {
7979 if (!HandleLValueIndirectMember(this->Info, E, Result, IFD))
7980 return false;
7981 } else
7982 return this->Error(E);
7983
7984 if (MD->getType()->isReferenceType()) {
7985 APValue RefValue;
7986 if (!handleLValueToRValueConversion(this->Info, E, MD->getType(), Result,
7987 RefValue))
7988 return false;
7989 return Success(RefValue, E);
7990 }
7991 return true;
7992 }
7993
VisitBinaryOperator(const BinaryOperator * E)7994 bool VisitBinaryOperator(const BinaryOperator *E) {
7995 switch (E->getOpcode()) {
7996 default:
7997 return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
7998
7999 case BO_PtrMemD:
8000 case BO_PtrMemI:
8001 return HandleMemberPointerAccess(this->Info, E, Result);
8002 }
8003 }
8004
VisitCastExpr(const CastExpr * E)8005 bool VisitCastExpr(const CastExpr *E) {
8006 switch (E->getCastKind()) {
8007 default:
8008 return ExprEvaluatorBaseTy::VisitCastExpr(E);
8009
8010 case CK_DerivedToBase:
8011 case CK_UncheckedDerivedToBase:
8012 if (!this->Visit(E->getSubExpr()))
8013 return false;
8014
8015 // Now figure out the necessary offset to add to the base LV to get from
8016 // the derived class to the base class.
8017 return HandleLValueBasePath(this->Info, E, E->getSubExpr()->getType(),
8018 Result);
8019 }
8020 }
8021 };
8022 }
8023
8024 //===----------------------------------------------------------------------===//
8025 // LValue Evaluation
8026 //
8027 // This is used for evaluating lvalues (in C and C++), xvalues (in C++11),
8028 // function designators (in C), decl references to void objects (in C), and
8029 // temporaries (if building with -Wno-address-of-temporary).
8030 //
8031 // LValue evaluation produces values comprising a base expression of one of the
8032 // following types:
8033 // - Declarations
8034 // * VarDecl
8035 // * FunctionDecl
8036 // - Literals
8037 // * CompoundLiteralExpr in C (and in global scope in C++)
8038 // * StringLiteral
8039 // * PredefinedExpr
8040 // * ObjCStringLiteralExpr
8041 // * ObjCEncodeExpr
8042 // * AddrLabelExpr
8043 // * BlockExpr
8044 // * CallExpr for a MakeStringConstant builtin
8045 // - typeid(T) expressions, as TypeInfoLValues
8046 // - Locals and temporaries
8047 // * MaterializeTemporaryExpr
8048 // * Any Expr, with a CallIndex indicating the function in which the temporary
8049 // was evaluated, for cases where the MaterializeTemporaryExpr is missing
8050 // from the AST (FIXME).
8051 // * A MaterializeTemporaryExpr that has static storage duration, with no
8052 // CallIndex, for a lifetime-extended temporary.
8053 // * The ConstantExpr that is currently being evaluated during evaluation of an
8054 // immediate invocation.
8055 // plus an offset in bytes.
8056 //===----------------------------------------------------------------------===//
8057 namespace {
8058 class LValueExprEvaluator
8059 : public LValueExprEvaluatorBase<LValueExprEvaluator> {
8060 public:
LValueExprEvaluator(EvalInfo & Info,LValue & Result,bool InvalidBaseOK)8061 LValueExprEvaluator(EvalInfo &Info, LValue &Result, bool InvalidBaseOK) :
8062 LValueExprEvaluatorBaseTy(Info, Result, InvalidBaseOK) {}
8063
8064 bool VisitVarDecl(const Expr *E, const VarDecl *VD);
8065 bool VisitUnaryPreIncDec(const UnaryOperator *UO);
8066
8067 bool VisitDeclRefExpr(const DeclRefExpr *E);
VisitPredefinedExpr(const PredefinedExpr * E)8068 bool VisitPredefinedExpr(const PredefinedExpr *E) { return Success(E); }
8069 bool VisitMaterializeTemporaryExpr(const MaterializeTemporaryExpr *E);
8070 bool VisitCompoundLiteralExpr(const CompoundLiteralExpr *E);
8071 bool VisitMemberExpr(const MemberExpr *E);
VisitStringLiteral(const StringLiteral * E)8072 bool VisitStringLiteral(const StringLiteral *E) { return Success(E); }
VisitObjCEncodeExpr(const ObjCEncodeExpr * E)8073 bool VisitObjCEncodeExpr(const ObjCEncodeExpr *E) { return Success(E); }
8074 bool VisitCXXTypeidExpr(const CXXTypeidExpr *E);
8075 bool VisitCXXUuidofExpr(const CXXUuidofExpr *E);
8076 bool VisitArraySubscriptExpr(const ArraySubscriptExpr *E);
8077 bool VisitUnaryDeref(const UnaryOperator *E);
8078 bool VisitUnaryReal(const UnaryOperator *E);
8079 bool VisitUnaryImag(const UnaryOperator *E);
VisitUnaryPreInc(const UnaryOperator * UO)8080 bool VisitUnaryPreInc(const UnaryOperator *UO) {
8081 return VisitUnaryPreIncDec(UO);
8082 }
VisitUnaryPreDec(const UnaryOperator * UO)8083 bool VisitUnaryPreDec(const UnaryOperator *UO) {
8084 return VisitUnaryPreIncDec(UO);
8085 }
8086 bool VisitBinAssign(const BinaryOperator *BO);
8087 bool VisitCompoundAssignOperator(const CompoundAssignOperator *CAO);
8088
VisitCastExpr(const CastExpr * E)8089 bool VisitCastExpr(const CastExpr *E) {
8090 switch (E->getCastKind()) {
8091 default:
8092 return LValueExprEvaluatorBaseTy::VisitCastExpr(E);
8093
8094 case CK_LValueBitCast:
8095 this->CCEDiag(E, diag::note_constexpr_invalid_cast) << 2;
8096 if (!Visit(E->getSubExpr()))
8097 return false;
8098 Result.Designator.setInvalid();
8099 return true;
8100
8101 case CK_BaseToDerived:
8102 if (!Visit(E->getSubExpr()))
8103 return false;
8104 return HandleBaseToDerivedCast(Info, E, Result);
8105
8106 case CK_Dynamic:
8107 if (!Visit(E->getSubExpr()))
8108 return false;
8109 return HandleDynamicCast(Info, cast<ExplicitCastExpr>(E), Result);
8110 }
8111 }
8112 };
8113 } // end anonymous namespace
8114
8115 /// Evaluate an expression as an lvalue. This can be legitimately called on
8116 /// expressions which are not glvalues, in three cases:
8117 /// * function designators in C, and
8118 /// * "extern void" objects
8119 /// * @selector() expressions in Objective-C
EvaluateLValue(const Expr * E,LValue & Result,EvalInfo & Info,bool InvalidBaseOK)8120 static bool EvaluateLValue(const Expr *E, LValue &Result, EvalInfo &Info,
8121 bool InvalidBaseOK) {
8122 assert(!E->isValueDependent());
8123 assert(E->isGLValue() || E->getType()->isFunctionType() ||
8124 E->getType()->isVoidType() || isa<ObjCSelectorExpr>(E));
8125 return LValueExprEvaluator(Info, Result, InvalidBaseOK).Visit(E);
8126 }
8127
VisitDeclRefExpr(const DeclRefExpr * E)8128 bool LValueExprEvaluator::VisitDeclRefExpr(const DeclRefExpr *E) {
8129 const NamedDecl *D = E->getDecl();
8130 if (isa<FunctionDecl, MSGuidDecl, TemplateParamObjectDecl>(D))
8131 return Success(cast<ValueDecl>(D));
8132 if (const VarDecl *VD = dyn_cast<VarDecl>(D))
8133 return VisitVarDecl(E, VD);
8134 if (const BindingDecl *BD = dyn_cast<BindingDecl>(D))
8135 return Visit(BD->getBinding());
8136 return Error(E);
8137 }
8138
8139
VisitVarDecl(const Expr * E,const VarDecl * VD)8140 bool LValueExprEvaluator::VisitVarDecl(const Expr *E, const VarDecl *VD) {
8141
8142 // If we are within a lambda's call operator, check whether the 'VD' referred
8143 // to within 'E' actually represents a lambda-capture that maps to a
8144 // data-member/field within the closure object, and if so, evaluate to the
8145 // field or what the field refers to.
8146 if (Info.CurrentCall && isLambdaCallOperator(Info.CurrentCall->Callee) &&
8147 isa<DeclRefExpr>(E) &&
8148 cast<DeclRefExpr>(E)->refersToEnclosingVariableOrCapture()) {
8149 // We don't always have a complete capture-map when checking or inferring if
8150 // the function call operator meets the requirements of a constexpr function
8151 // - but we don't need to evaluate the captures to determine constexprness
8152 // (dcl.constexpr C++17).
8153 if (Info.checkingPotentialConstantExpression())
8154 return false;
8155
8156 if (auto *FD = Info.CurrentCall->LambdaCaptureFields.lookup(VD)) {
8157 // Start with 'Result' referring to the complete closure object...
8158 Result = *Info.CurrentCall->This;
8159 // ... then update it to refer to the field of the closure object
8160 // that represents the capture.
8161 if (!HandleLValueMember(Info, E, Result, FD))
8162 return false;
8163 // And if the field is of reference type, update 'Result' to refer to what
8164 // the field refers to.
8165 if (FD->getType()->isReferenceType()) {
8166 APValue RVal;
8167 if (!handleLValueToRValueConversion(Info, E, FD->getType(), Result,
8168 RVal))
8169 return false;
8170 Result.setFrom(Info.Ctx, RVal);
8171 }
8172 return true;
8173 }
8174 }
8175
8176 CallStackFrame *Frame = nullptr;
8177 unsigned Version = 0;
8178 if (VD->hasLocalStorage()) {
8179 // Only if a local variable was declared in the function currently being
8180 // evaluated, do we expect to be able to find its value in the current
8181 // frame. (Otherwise it was likely declared in an enclosing context and
8182 // could either have a valid evaluatable value (for e.g. a constexpr
8183 // variable) or be ill-formed (and trigger an appropriate evaluation
8184 // diagnostic)).
8185 CallStackFrame *CurrFrame = Info.CurrentCall;
8186 if (CurrFrame->Callee && CurrFrame->Callee->Equals(VD->getDeclContext())) {
8187 // Function parameters are stored in some caller's frame. (Usually the
8188 // immediate caller, but for an inherited constructor they may be more
8189 // distant.)
8190 if (auto *PVD = dyn_cast<ParmVarDecl>(VD)) {
8191 if (CurrFrame->Arguments) {
8192 VD = CurrFrame->Arguments.getOrigParam(PVD);
8193 Frame =
8194 Info.getCallFrameAndDepth(CurrFrame->Arguments.CallIndex).first;
8195 Version = CurrFrame->Arguments.Version;
8196 }
8197 } else {
8198 Frame = CurrFrame;
8199 Version = CurrFrame->getCurrentTemporaryVersion(VD);
8200 }
8201 }
8202 }
8203
8204 if (!VD->getType()->isReferenceType()) {
8205 if (Frame) {
8206 Result.set({VD, Frame->Index, Version});
8207 return true;
8208 }
8209 return Success(VD);
8210 }
8211
8212 if (!Info.getLangOpts().CPlusPlus11) {
8213 Info.CCEDiag(E, diag::note_constexpr_ltor_non_integral, 1)
8214 << VD << VD->getType();
8215 Info.Note(VD->getLocation(), diag::note_declared_at);
8216 }
8217
8218 APValue *V;
8219 if (!evaluateVarDeclInit(Info, E, VD, Frame, Version, V))
8220 return false;
8221 if (!V->hasValue()) {
8222 // FIXME: Is it possible for V to be indeterminate here? If so, we should
8223 // adjust the diagnostic to say that.
8224 if (!Info.checkingPotentialConstantExpression())
8225 Info.FFDiag(E, diag::note_constexpr_use_uninit_reference);
8226 return false;
8227 }
8228 return Success(*V, E);
8229 }
8230
VisitMaterializeTemporaryExpr(const MaterializeTemporaryExpr * E)8231 bool LValueExprEvaluator::VisitMaterializeTemporaryExpr(
8232 const MaterializeTemporaryExpr *E) {
8233 // Walk through the expression to find the materialized temporary itself.
8234 SmallVector<const Expr *, 2> CommaLHSs;
8235 SmallVector<SubobjectAdjustment, 2> Adjustments;
8236 const Expr *Inner =
8237 E->getSubExpr()->skipRValueSubobjectAdjustments(CommaLHSs, Adjustments);
8238
8239 // If we passed any comma operators, evaluate their LHSs.
8240 for (unsigned I = 0, N = CommaLHSs.size(); I != N; ++I)
8241 if (!EvaluateIgnoredValue(Info, CommaLHSs[I]))
8242 return false;
8243
8244 // A materialized temporary with static storage duration can appear within the
8245 // result of a constant expression evaluation, so we need to preserve its
8246 // value for use outside this evaluation.
8247 APValue *Value;
8248 if (E->getStorageDuration() == SD_Static) {
8249 // FIXME: What about SD_Thread?
8250 Value = E->getOrCreateValue(true);
8251 *Value = APValue();
8252 Result.set(E);
8253 } else {
8254 Value = &Info.CurrentCall->createTemporary(
8255 E, E->getType(),
8256 E->getStorageDuration() == SD_FullExpression ? ScopeKind::FullExpression
8257 : ScopeKind::Block,
8258 Result);
8259 }
8260
8261 QualType Type = Inner->getType();
8262
8263 // Materialize the temporary itself.
8264 if (!EvaluateInPlace(*Value, Info, Result, Inner)) {
8265 *Value = APValue();
8266 return false;
8267 }
8268
8269 // Adjust our lvalue to refer to the desired subobject.
8270 for (unsigned I = Adjustments.size(); I != 0; /**/) {
8271 --I;
8272 switch (Adjustments[I].Kind) {
8273 case SubobjectAdjustment::DerivedToBaseAdjustment:
8274 if (!HandleLValueBasePath(Info, Adjustments[I].DerivedToBase.BasePath,
8275 Type, Result))
8276 return false;
8277 Type = Adjustments[I].DerivedToBase.BasePath->getType();
8278 break;
8279
8280 case SubobjectAdjustment::FieldAdjustment:
8281 if (!HandleLValueMember(Info, E, Result, Adjustments[I].Field))
8282 return false;
8283 Type = Adjustments[I].Field->getType();
8284 break;
8285
8286 case SubobjectAdjustment::MemberPointerAdjustment:
8287 if (!HandleMemberPointerAccess(this->Info, Type, Result,
8288 Adjustments[I].Ptr.RHS))
8289 return false;
8290 Type = Adjustments[I].Ptr.MPT->getPointeeType();
8291 break;
8292 }
8293 }
8294
8295 return true;
8296 }
8297
8298 bool
VisitCompoundLiteralExpr(const CompoundLiteralExpr * E)8299 LValueExprEvaluator::VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) {
8300 assert((!Info.getLangOpts().CPlusPlus || E->isFileScope()) &&
8301 "lvalue compound literal in c++?");
8302 // Defer visiting the literal until the lvalue-to-rvalue conversion. We can
8303 // only see this when folding in C, so there's no standard to follow here.
8304 return Success(E);
8305 }
8306
VisitCXXTypeidExpr(const CXXTypeidExpr * E)8307 bool LValueExprEvaluator::VisitCXXTypeidExpr(const CXXTypeidExpr *E) {
8308 TypeInfoLValue TypeInfo;
8309
8310 if (!E->isPotentiallyEvaluated()) {
8311 if (E->isTypeOperand())
8312 TypeInfo = TypeInfoLValue(E->getTypeOperand(Info.Ctx).getTypePtr());
8313 else
8314 TypeInfo = TypeInfoLValue(E->getExprOperand()->getType().getTypePtr());
8315 } else {
8316 if (!Info.Ctx.getLangOpts().CPlusPlus20) {
8317 Info.CCEDiag(E, diag::note_constexpr_typeid_polymorphic)
8318 << E->getExprOperand()->getType()
8319 << E->getExprOperand()->getSourceRange();
8320 }
8321
8322 if (!Visit(E->getExprOperand()))
8323 return false;
8324
8325 Optional<DynamicType> DynType =
8326 ComputeDynamicType(Info, E, Result, AK_TypeId);
8327 if (!DynType)
8328 return false;
8329
8330 TypeInfo =
8331 TypeInfoLValue(Info.Ctx.getRecordType(DynType->Type).getTypePtr());
8332 }
8333
8334 return Success(APValue::LValueBase::getTypeInfo(TypeInfo, E->getType()));
8335 }
8336
VisitCXXUuidofExpr(const CXXUuidofExpr * E)8337 bool LValueExprEvaluator::VisitCXXUuidofExpr(const CXXUuidofExpr *E) {
8338 return Success(E->getGuidDecl());
8339 }
8340
VisitMemberExpr(const MemberExpr * E)8341 bool LValueExprEvaluator::VisitMemberExpr(const MemberExpr *E) {
8342 // Handle static data members.
8343 if (const VarDecl *VD = dyn_cast<VarDecl>(E->getMemberDecl())) {
8344 VisitIgnoredBaseExpression(E->getBase());
8345 return VisitVarDecl(E, VD);
8346 }
8347
8348 // Handle static member functions.
8349 if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(E->getMemberDecl())) {
8350 if (MD->isStatic()) {
8351 VisitIgnoredBaseExpression(E->getBase());
8352 return Success(MD);
8353 }
8354 }
8355
8356 // Handle non-static data members.
8357 return LValueExprEvaluatorBaseTy::VisitMemberExpr(E);
8358 }
8359
VisitArraySubscriptExpr(const ArraySubscriptExpr * E)8360 bool LValueExprEvaluator::VisitArraySubscriptExpr(const ArraySubscriptExpr *E) {
8361 // FIXME: Deal with vectors as array subscript bases.
8362 if (E->getBase()->getType()->isVectorType())
8363 return Error(E);
8364
8365 APSInt Index;
8366 bool Success = true;
8367
8368 // C++17's rules require us to evaluate the LHS first, regardless of which
8369 // side is the base.
8370 for (const Expr *SubExpr : {E->getLHS(), E->getRHS()}) {
8371 if (SubExpr == E->getBase() ? !evaluatePointer(SubExpr, Result)
8372 : !EvaluateInteger(SubExpr, Index, Info)) {
8373 if (!Info.noteFailure())
8374 return false;
8375 Success = false;
8376 }
8377 }
8378
8379 return Success &&
8380 HandleLValueArrayAdjustment(Info, E, Result, E->getType(), Index);
8381 }
8382
VisitUnaryDeref(const UnaryOperator * E)8383 bool LValueExprEvaluator::VisitUnaryDeref(const UnaryOperator *E) {
8384 return evaluatePointer(E->getSubExpr(), Result);
8385 }
8386
VisitUnaryReal(const UnaryOperator * E)8387 bool LValueExprEvaluator::VisitUnaryReal(const UnaryOperator *E) {
8388 if (!Visit(E->getSubExpr()))
8389 return false;
8390 // __real is a no-op on scalar lvalues.
8391 if (E->getSubExpr()->getType()->isAnyComplexType())
8392 HandleLValueComplexElement(Info, E, Result, E->getType(), false);
8393 return true;
8394 }
8395
VisitUnaryImag(const UnaryOperator * E)8396 bool LValueExprEvaluator::VisitUnaryImag(const UnaryOperator *E) {
8397 assert(E->getSubExpr()->getType()->isAnyComplexType() &&
8398 "lvalue __imag__ on scalar?");
8399 if (!Visit(E->getSubExpr()))
8400 return false;
8401 HandleLValueComplexElement(Info, E, Result, E->getType(), true);
8402 return true;
8403 }
8404
VisitUnaryPreIncDec(const UnaryOperator * UO)8405 bool LValueExprEvaluator::VisitUnaryPreIncDec(const UnaryOperator *UO) {
8406 if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure())
8407 return Error(UO);
8408
8409 if (!this->Visit(UO->getSubExpr()))
8410 return false;
8411
8412 return handleIncDec(
8413 this->Info, UO, Result, UO->getSubExpr()->getType(),
8414 UO->isIncrementOp(), nullptr);
8415 }
8416
VisitCompoundAssignOperator(const CompoundAssignOperator * CAO)8417 bool LValueExprEvaluator::VisitCompoundAssignOperator(
8418 const CompoundAssignOperator *CAO) {
8419 if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure())
8420 return Error(CAO);
8421
8422 bool Success = true;
8423
8424 // C++17 onwards require that we evaluate the RHS first.
8425 APValue RHS;
8426 if (!Evaluate(RHS, this->Info, CAO->getRHS())) {
8427 if (!Info.noteFailure())
8428 return false;
8429 Success = false;
8430 }
8431
8432 // The overall lvalue result is the result of evaluating the LHS.
8433 if (!this->Visit(CAO->getLHS()) || !Success)
8434 return false;
8435
8436 return handleCompoundAssignment(
8437 this->Info, CAO,
8438 Result, CAO->getLHS()->getType(), CAO->getComputationLHSType(),
8439 CAO->getOpForCompoundAssignment(CAO->getOpcode()), RHS);
8440 }
8441
VisitBinAssign(const BinaryOperator * E)8442 bool LValueExprEvaluator::VisitBinAssign(const BinaryOperator *E) {
8443 if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure())
8444 return Error(E);
8445
8446 bool Success = true;
8447
8448 // C++17 onwards require that we evaluate the RHS first.
8449 APValue NewVal;
8450 if (!Evaluate(NewVal, this->Info, E->getRHS())) {
8451 if (!Info.noteFailure())
8452 return false;
8453 Success = false;
8454 }
8455
8456 if (!this->Visit(E->getLHS()) || !Success)
8457 return false;
8458
8459 if (Info.getLangOpts().CPlusPlus20 &&
8460 !HandleUnionActiveMemberChange(Info, E->getLHS(), Result))
8461 return false;
8462
8463 return handleAssignment(this->Info, E, Result, E->getLHS()->getType(),
8464 NewVal);
8465 }
8466
8467 //===----------------------------------------------------------------------===//
8468 // Pointer Evaluation
8469 //===----------------------------------------------------------------------===//
8470
8471 /// Attempts to compute the number of bytes available at the pointer
8472 /// returned by a function with the alloc_size attribute. Returns true if we
8473 /// were successful. Places an unsigned number into `Result`.
8474 ///
8475 /// This expects the given CallExpr to be a call to a function with an
8476 /// alloc_size attribute.
getBytesReturnedByAllocSizeCall(const ASTContext & Ctx,const CallExpr * Call,llvm::APInt & Result)8477 static bool getBytesReturnedByAllocSizeCall(const ASTContext &Ctx,
8478 const CallExpr *Call,
8479 llvm::APInt &Result) {
8480 const AllocSizeAttr *AllocSize = getAllocSizeAttr(Call);
8481
8482 assert(AllocSize && AllocSize->getElemSizeParam().isValid());
8483 unsigned SizeArgNo = AllocSize->getElemSizeParam().getASTIndex();
8484 unsigned BitsInSizeT = Ctx.getTypeSize(Ctx.getSizeType());
8485 if (Call->getNumArgs() <= SizeArgNo)
8486 return false;
8487
8488 auto EvaluateAsSizeT = [&](const Expr *E, APSInt &Into) {
8489 Expr::EvalResult ExprResult;
8490 if (!E->EvaluateAsInt(ExprResult, Ctx, Expr::SE_AllowSideEffects))
8491 return false;
8492 Into = ExprResult.Val.getInt();
8493 if (Into.isNegative() || !Into.isIntN(BitsInSizeT))
8494 return false;
8495 Into = Into.zextOrSelf(BitsInSizeT);
8496 return true;
8497 };
8498
8499 APSInt SizeOfElem;
8500 if (!EvaluateAsSizeT(Call->getArg(SizeArgNo), SizeOfElem))
8501 return false;
8502
8503 if (!AllocSize->getNumElemsParam().isValid()) {
8504 Result = std::move(SizeOfElem);
8505 return true;
8506 }
8507
8508 APSInt NumberOfElems;
8509 unsigned NumArgNo = AllocSize->getNumElemsParam().getASTIndex();
8510 if (!EvaluateAsSizeT(Call->getArg(NumArgNo), NumberOfElems))
8511 return false;
8512
8513 bool Overflow;
8514 llvm::APInt BytesAvailable = SizeOfElem.umul_ov(NumberOfElems, Overflow);
8515 if (Overflow)
8516 return false;
8517
8518 Result = std::move(BytesAvailable);
8519 return true;
8520 }
8521
8522 /// Convenience function. LVal's base must be a call to an alloc_size
8523 /// function.
getBytesReturnedByAllocSizeCall(const ASTContext & Ctx,const LValue & LVal,llvm::APInt & Result)8524 static bool getBytesReturnedByAllocSizeCall(const ASTContext &Ctx,
8525 const LValue &LVal,
8526 llvm::APInt &Result) {
8527 assert(isBaseAnAllocSizeCall(LVal.getLValueBase()) &&
8528 "Can't get the size of a non alloc_size function");
8529 const auto *Base = LVal.getLValueBase().get<const Expr *>();
8530 const CallExpr *CE = tryUnwrapAllocSizeCall(Base);
8531 return getBytesReturnedByAllocSizeCall(Ctx, CE, Result);
8532 }
8533
8534 /// Attempts to evaluate the given LValueBase as the result of a call to
8535 /// a function with the alloc_size attribute. If it was possible to do so, this
8536 /// function will return true, make Result's Base point to said function call,
8537 /// and mark Result's Base as invalid.
evaluateLValueAsAllocSize(EvalInfo & Info,APValue::LValueBase Base,LValue & Result)8538 static bool evaluateLValueAsAllocSize(EvalInfo &Info, APValue::LValueBase Base,
8539 LValue &Result) {
8540 if (Base.isNull())
8541 return false;
8542
8543 // Because we do no form of static analysis, we only support const variables.
8544 //
8545 // Additionally, we can't support parameters, nor can we support static
8546 // variables (in the latter case, use-before-assign isn't UB; in the former,
8547 // we have no clue what they'll be assigned to).
8548 const auto *VD =
8549 dyn_cast_or_null<VarDecl>(Base.dyn_cast<const ValueDecl *>());
8550 if (!VD || !VD->isLocalVarDecl() || !VD->getType().isConstQualified())
8551 return false;
8552
8553 const Expr *Init = VD->getAnyInitializer();
8554 if (!Init)
8555 return false;
8556
8557 const Expr *E = Init->IgnoreParens();
8558 if (!tryUnwrapAllocSizeCall(E))
8559 return false;
8560
8561 // Store E instead of E unwrapped so that the type of the LValue's base is
8562 // what the user wanted.
8563 Result.setInvalid(E);
8564
8565 QualType Pointee = E->getType()->castAs<PointerType>()->getPointeeType();
8566 Result.addUnsizedArray(Info, E, Pointee);
8567 return true;
8568 }
8569
8570 namespace {
8571 class PointerExprEvaluator
8572 : public ExprEvaluatorBase<PointerExprEvaluator> {
8573 LValue &Result;
8574 bool InvalidBaseOK;
8575
Success(const Expr * E)8576 bool Success(const Expr *E) {
8577 Result.set(E);
8578 return true;
8579 }
8580
evaluateLValue(const Expr * E,LValue & Result)8581 bool evaluateLValue(const Expr *E, LValue &Result) {
8582 return EvaluateLValue(E, Result, Info, InvalidBaseOK);
8583 }
8584
evaluatePointer(const Expr * E,LValue & Result)8585 bool evaluatePointer(const Expr *E, LValue &Result) {
8586 return EvaluatePointer(E, Result, Info, InvalidBaseOK);
8587 }
8588
8589 bool visitNonBuiltinCallExpr(const CallExpr *E);
8590 public:
8591
PointerExprEvaluator(EvalInfo & info,LValue & Result,bool InvalidBaseOK)8592 PointerExprEvaluator(EvalInfo &info, LValue &Result, bool InvalidBaseOK)
8593 : ExprEvaluatorBaseTy(info), Result(Result),
8594 InvalidBaseOK(InvalidBaseOK) {}
8595
Success(const APValue & V,const Expr * E)8596 bool Success(const APValue &V, const Expr *E) {
8597 Result.setFrom(Info.Ctx, V);
8598 return true;
8599 }
ZeroInitialization(const Expr * E)8600 bool ZeroInitialization(const Expr *E) {
8601 Result.setNull(Info.Ctx, E->getType());
8602 return true;
8603 }
8604
8605 bool VisitBinaryOperator(const BinaryOperator *E);
8606 bool VisitCastExpr(const CastExpr* E);
8607 bool VisitUnaryAddrOf(const UnaryOperator *E);
VisitObjCStringLiteral(const ObjCStringLiteral * E)8608 bool VisitObjCStringLiteral(const ObjCStringLiteral *E)
8609 { return Success(E); }
VisitObjCBoxedExpr(const ObjCBoxedExpr * E)8610 bool VisitObjCBoxedExpr(const ObjCBoxedExpr *E) {
8611 if (E->isExpressibleAsConstantInitializer())
8612 return Success(E);
8613 if (Info.noteFailure())
8614 EvaluateIgnoredValue(Info, E->getSubExpr());
8615 return Error(E);
8616 }
VisitAddrLabelExpr(const AddrLabelExpr * E)8617 bool VisitAddrLabelExpr(const AddrLabelExpr *E)
8618 { return Success(E); }
8619 bool VisitCallExpr(const CallExpr *E);
8620 bool VisitBuiltinCallExpr(const CallExpr *E, unsigned BuiltinOp);
VisitBlockExpr(const BlockExpr * E)8621 bool VisitBlockExpr(const BlockExpr *E) {
8622 if (!E->getBlockDecl()->hasCaptures())
8623 return Success(E);
8624 return Error(E);
8625 }
VisitCXXThisExpr(const CXXThisExpr * E)8626 bool VisitCXXThisExpr(const CXXThisExpr *E) {
8627 // Can't look at 'this' when checking a potential constant expression.
8628 if (Info.checkingPotentialConstantExpression())
8629 return false;
8630 if (!Info.CurrentCall->This) {
8631 if (Info.getLangOpts().CPlusPlus11)
8632 Info.FFDiag(E, diag::note_constexpr_this) << E->isImplicit();
8633 else
8634 Info.FFDiag(E);
8635 return false;
8636 }
8637 Result = *Info.CurrentCall->This;
8638 // If we are inside a lambda's call operator, the 'this' expression refers
8639 // to the enclosing '*this' object (either by value or reference) which is
8640 // either copied into the closure object's field that represents the '*this'
8641 // or refers to '*this'.
8642 if (isLambdaCallOperator(Info.CurrentCall->Callee)) {
8643 // Ensure we actually have captured 'this'. (an error will have
8644 // been previously reported if not).
8645 if (!Info.CurrentCall->LambdaThisCaptureField)
8646 return false;
8647
8648 // Update 'Result' to refer to the data member/field of the closure object
8649 // that represents the '*this' capture.
8650 if (!HandleLValueMember(Info, E, Result,
8651 Info.CurrentCall->LambdaThisCaptureField))
8652 return false;
8653 // If we captured '*this' by reference, replace the field with its referent.
8654 if (Info.CurrentCall->LambdaThisCaptureField->getType()
8655 ->isPointerType()) {
8656 APValue RVal;
8657 if (!handleLValueToRValueConversion(Info, E, E->getType(), Result,
8658 RVal))
8659 return false;
8660
8661 Result.setFrom(Info.Ctx, RVal);
8662 }
8663 }
8664 return true;
8665 }
8666
8667 bool VisitCXXNewExpr(const CXXNewExpr *E);
8668
VisitSourceLocExpr(const SourceLocExpr * E)8669 bool VisitSourceLocExpr(const SourceLocExpr *E) {
8670 assert(E->isStringType() && "SourceLocExpr isn't a pointer type?");
8671 APValue LValResult = E->EvaluateInContext(
8672 Info.Ctx, Info.CurrentCall->CurSourceLocExprScope.getDefaultExpr());
8673 Result.setFrom(Info.Ctx, LValResult);
8674 return true;
8675 }
8676
VisitSYCLUniqueStableNameExpr(const SYCLUniqueStableNameExpr * E)8677 bool VisitSYCLUniqueStableNameExpr(const SYCLUniqueStableNameExpr *E) {
8678 std::string ResultStr = E->ComputeName(Info.Ctx);
8679
8680 QualType CharTy = Info.Ctx.CharTy.withConst();
8681 APInt Size(Info.Ctx.getTypeSize(Info.Ctx.getSizeType()),
8682 ResultStr.size() + 1);
8683 QualType ArrayTy = Info.Ctx.getConstantArrayType(CharTy, Size, nullptr,
8684 ArrayType::Normal, 0);
8685
8686 StringLiteral *SL =
8687 StringLiteral::Create(Info.Ctx, ResultStr, StringLiteral::Ascii,
8688 /*Pascal*/ false, ArrayTy, E->getLocation());
8689
8690 evaluateLValue(SL, Result);
8691 Result.addArray(Info, E, cast<ConstantArrayType>(ArrayTy));
8692 return true;
8693 }
8694
8695 // FIXME: Missing: @protocol, @selector
8696 };
8697 } // end anonymous namespace
8698
EvaluatePointer(const Expr * E,LValue & Result,EvalInfo & Info,bool InvalidBaseOK)8699 static bool EvaluatePointer(const Expr* E, LValue& Result, EvalInfo &Info,
8700 bool InvalidBaseOK) {
8701 assert(!E->isValueDependent());
8702 assert(E->isPRValue() && E->getType()->hasPointerRepresentation());
8703 return PointerExprEvaluator(Info, Result, InvalidBaseOK).Visit(E);
8704 }
8705
VisitBinaryOperator(const BinaryOperator * E)8706 bool PointerExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
8707 if (E->getOpcode() != BO_Add &&
8708 E->getOpcode() != BO_Sub)
8709 return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
8710
8711 const Expr *PExp = E->getLHS();
8712 const Expr *IExp = E->getRHS();
8713 if (IExp->getType()->isPointerType())
8714 std::swap(PExp, IExp);
8715
8716 bool EvalPtrOK = evaluatePointer(PExp, Result);
8717 if (!EvalPtrOK && !Info.noteFailure())
8718 return false;
8719
8720 llvm::APSInt Offset;
8721 if (!EvaluateInteger(IExp, Offset, Info) || !EvalPtrOK)
8722 return false;
8723
8724 if (E->getOpcode() == BO_Sub)
8725 negateAsSigned(Offset);
8726
8727 QualType Pointee = PExp->getType()->castAs<PointerType>()->getPointeeType();
8728 return HandleLValueArrayAdjustment(Info, E, Result, Pointee, Offset);
8729 }
8730
VisitUnaryAddrOf(const UnaryOperator * E)8731 bool PointerExprEvaluator::VisitUnaryAddrOf(const UnaryOperator *E) {
8732 return evaluateLValue(E->getSubExpr(), Result);
8733 }
8734
VisitCastExpr(const CastExpr * E)8735 bool PointerExprEvaluator::VisitCastExpr(const CastExpr *E) {
8736 const Expr *SubExpr = E->getSubExpr();
8737
8738 switch (E->getCastKind()) {
8739 default:
8740 break;
8741 case CK_BitCast:
8742 case CK_CPointerToObjCPointerCast:
8743 case CK_BlockPointerToObjCPointerCast:
8744 case CK_AnyPointerToBlockPointerCast:
8745 case CK_AddressSpaceConversion:
8746 if (!Visit(SubExpr))
8747 return false;
8748 // Bitcasts to cv void* are static_casts, not reinterpret_casts, so are
8749 // permitted in constant expressions in C++11. Bitcasts from cv void* are
8750 // also static_casts, but we disallow them as a resolution to DR1312.
8751 if (!E->getType()->isVoidPointerType()) {
8752 if (!Result.InvalidBase && !Result.Designator.Invalid &&
8753 !Result.IsNullPtr &&
8754 Info.Ctx.hasSameUnqualifiedType(Result.Designator.getType(Info.Ctx),
8755 E->getType()->getPointeeType()) &&
8756 Info.getStdAllocatorCaller("allocate")) {
8757 // Inside a call to std::allocator::allocate and friends, we permit
8758 // casting from void* back to cv1 T* for a pointer that points to a
8759 // cv2 T.
8760 } else {
8761 Result.Designator.setInvalid();
8762 if (SubExpr->getType()->isVoidPointerType())
8763 CCEDiag(E, diag::note_constexpr_invalid_cast)
8764 << 3 << SubExpr->getType();
8765 else
8766 CCEDiag(E, diag::note_constexpr_invalid_cast) << 2;
8767 }
8768 }
8769 if (E->getCastKind() == CK_AddressSpaceConversion && Result.IsNullPtr)
8770 ZeroInitialization(E);
8771 return true;
8772
8773 case CK_DerivedToBase:
8774 case CK_UncheckedDerivedToBase:
8775 if (!evaluatePointer(E->getSubExpr(), Result))
8776 return false;
8777 if (!Result.Base && Result.Offset.isZero())
8778 return true;
8779
8780 // Now figure out the necessary offset to add to the base LV to get from
8781 // the derived class to the base class.
8782 return HandleLValueBasePath(Info, E, E->getSubExpr()->getType()->
8783 castAs<PointerType>()->getPointeeType(),
8784 Result);
8785
8786 case CK_BaseToDerived:
8787 if (!Visit(E->getSubExpr()))
8788 return false;
8789 if (!Result.Base && Result.Offset.isZero())
8790 return true;
8791 return HandleBaseToDerivedCast(Info, E, Result);
8792
8793 case CK_Dynamic:
8794 if (!Visit(E->getSubExpr()))
8795 return false;
8796 return HandleDynamicCast(Info, cast<ExplicitCastExpr>(E), Result);
8797
8798 case CK_NullToPointer:
8799 VisitIgnoredValue(E->getSubExpr());
8800 return ZeroInitialization(E);
8801
8802 case CK_IntegralToPointer: {
8803 CCEDiag(E, diag::note_constexpr_invalid_cast) << 2;
8804
8805 APValue Value;
8806 if (!EvaluateIntegerOrLValue(SubExpr, Value, Info))
8807 break;
8808
8809 if (Value.isInt()) {
8810 unsigned Size = Info.Ctx.getTypeSize(E->getType());
8811 uint64_t N = Value.getInt().extOrTrunc(Size).getZExtValue();
8812 Result.Base = (Expr*)nullptr;
8813 Result.InvalidBase = false;
8814 Result.Offset = CharUnits::fromQuantity(N);
8815 Result.Designator.setInvalid();
8816 Result.IsNullPtr = false;
8817 return true;
8818 } else {
8819 // Cast is of an lvalue, no need to change value.
8820 Result.setFrom(Info.Ctx, Value);
8821 return true;
8822 }
8823 }
8824
8825 case CK_ArrayToPointerDecay: {
8826 if (SubExpr->isGLValue()) {
8827 if (!evaluateLValue(SubExpr, Result))
8828 return false;
8829 } else {
8830 APValue &Value = Info.CurrentCall->createTemporary(
8831 SubExpr, SubExpr->getType(), ScopeKind::FullExpression, Result);
8832 if (!EvaluateInPlace(Value, Info, Result, SubExpr))
8833 return false;
8834 }
8835 // The result is a pointer to the first element of the array.
8836 auto *AT = Info.Ctx.getAsArrayType(SubExpr->getType());
8837 if (auto *CAT = dyn_cast<ConstantArrayType>(AT))
8838 Result.addArray(Info, E, CAT);
8839 else
8840 Result.addUnsizedArray(Info, E, AT->getElementType());
8841 return true;
8842 }
8843
8844 case CK_FunctionToPointerDecay:
8845 return evaluateLValue(SubExpr, Result);
8846
8847 case CK_LValueToRValue: {
8848 LValue LVal;
8849 if (!evaluateLValue(E->getSubExpr(), LVal))
8850 return false;
8851
8852 APValue RVal;
8853 // Note, we use the subexpression's type in order to retain cv-qualifiers.
8854 if (!handleLValueToRValueConversion(Info, E, E->getSubExpr()->getType(),
8855 LVal, RVal))
8856 return InvalidBaseOK &&
8857 evaluateLValueAsAllocSize(Info, LVal.Base, Result);
8858 return Success(RVal, E);
8859 }
8860 }
8861
8862 return ExprEvaluatorBaseTy::VisitCastExpr(E);
8863 }
8864
GetAlignOfType(EvalInfo & Info,QualType T,UnaryExprOrTypeTrait ExprKind)8865 static CharUnits GetAlignOfType(EvalInfo &Info, QualType T,
8866 UnaryExprOrTypeTrait ExprKind) {
8867 // C++ [expr.alignof]p3:
8868 // When alignof is applied to a reference type, the result is the
8869 // alignment of the referenced type.
8870 if (const ReferenceType *Ref = T->getAs<ReferenceType>())
8871 T = Ref->getPointeeType();
8872
8873 if (T.getQualifiers().hasUnaligned())
8874 return CharUnits::One();
8875
8876 const bool AlignOfReturnsPreferred =
8877 Info.Ctx.getLangOpts().getClangABICompat() <= LangOptions::ClangABI::Ver7;
8878
8879 // __alignof is defined to return the preferred alignment.
8880 // Before 8, clang returned the preferred alignment for alignof and _Alignof
8881 // as well.
8882 if (ExprKind == UETT_PreferredAlignOf || AlignOfReturnsPreferred)
8883 return Info.Ctx.toCharUnitsFromBits(
8884 Info.Ctx.getPreferredTypeAlign(T.getTypePtr()));
8885 // alignof and _Alignof are defined to return the ABI alignment.
8886 else if (ExprKind == UETT_AlignOf)
8887 return Info.Ctx.getTypeAlignInChars(T.getTypePtr());
8888 else
8889 llvm_unreachable("GetAlignOfType on a non-alignment ExprKind");
8890 }
8891
GetAlignOfExpr(EvalInfo & Info,const Expr * E,UnaryExprOrTypeTrait ExprKind)8892 static CharUnits GetAlignOfExpr(EvalInfo &Info, const Expr *E,
8893 UnaryExprOrTypeTrait ExprKind) {
8894 E = E->IgnoreParens();
8895
8896 // The kinds of expressions that we have special-case logic here for
8897 // should be kept up to date with the special checks for those
8898 // expressions in Sema.
8899
8900 // alignof decl is always accepted, even if it doesn't make sense: we default
8901 // to 1 in those cases.
8902 if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
8903 return Info.Ctx.getDeclAlign(DRE->getDecl(),
8904 /*RefAsPointee*/true);
8905
8906 if (const MemberExpr *ME = dyn_cast<MemberExpr>(E))
8907 return Info.Ctx.getDeclAlign(ME->getMemberDecl(),
8908 /*RefAsPointee*/true);
8909
8910 return GetAlignOfType(Info, E->getType(), ExprKind);
8911 }
8912
getBaseAlignment(EvalInfo & Info,const LValue & Value)8913 static CharUnits getBaseAlignment(EvalInfo &Info, const LValue &Value) {
8914 if (const auto *VD = Value.Base.dyn_cast<const ValueDecl *>())
8915 return Info.Ctx.getDeclAlign(VD);
8916 if (const auto *E = Value.Base.dyn_cast<const Expr *>())
8917 return GetAlignOfExpr(Info, E, UETT_AlignOf);
8918 return GetAlignOfType(Info, Value.Base.getTypeInfoType(), UETT_AlignOf);
8919 }
8920
8921 /// Evaluate the value of the alignment argument to __builtin_align_{up,down},
8922 /// __builtin_is_aligned and __builtin_assume_aligned.
getAlignmentArgument(const Expr * E,QualType ForType,EvalInfo & Info,APSInt & Alignment)8923 static bool getAlignmentArgument(const Expr *E, QualType ForType,
8924 EvalInfo &Info, APSInt &Alignment) {
8925 if (!EvaluateInteger(E, Alignment, Info))
8926 return false;
8927 if (Alignment < 0 || !Alignment.isPowerOf2()) {
8928 Info.FFDiag(E, diag::note_constexpr_invalid_alignment) << Alignment;
8929 return false;
8930 }
8931 unsigned SrcWidth = Info.Ctx.getIntWidth(ForType);
8932 APSInt MaxValue(APInt::getOneBitSet(SrcWidth, SrcWidth - 1));
8933 if (APSInt::compareValues(Alignment, MaxValue) > 0) {
8934 Info.FFDiag(E, diag::note_constexpr_alignment_too_big)
8935 << MaxValue << ForType << Alignment;
8936 return false;
8937 }
8938 // Ensure both alignment and source value have the same bit width so that we
8939 // don't assert when computing the resulting value.
8940 APSInt ExtAlignment =
8941 APSInt(Alignment.zextOrTrunc(SrcWidth), /*isUnsigned=*/true);
8942 assert(APSInt::compareValues(Alignment, ExtAlignment) == 0 &&
8943 "Alignment should not be changed by ext/trunc");
8944 Alignment = ExtAlignment;
8945 assert(Alignment.getBitWidth() == SrcWidth);
8946 return true;
8947 }
8948
8949 // To be clear: this happily visits unsupported builtins. Better name welcomed.
visitNonBuiltinCallExpr(const CallExpr * E)8950 bool PointerExprEvaluator::visitNonBuiltinCallExpr(const CallExpr *E) {
8951 if (ExprEvaluatorBaseTy::VisitCallExpr(E))
8952 return true;
8953
8954 if (!(InvalidBaseOK && getAllocSizeAttr(E)))
8955 return false;
8956
8957 Result.setInvalid(E);
8958 QualType PointeeTy = E->getType()->castAs<PointerType>()->getPointeeType();
8959 Result.addUnsizedArray(Info, E, PointeeTy);
8960 return true;
8961 }
8962
VisitCallExpr(const CallExpr * E)8963 bool PointerExprEvaluator::VisitCallExpr(const CallExpr *E) {
8964 if (IsStringLiteralCall(E))
8965 return Success(E);
8966
8967 if (unsigned BuiltinOp = E->getBuiltinCallee())
8968 return VisitBuiltinCallExpr(E, BuiltinOp);
8969
8970 return visitNonBuiltinCallExpr(E);
8971 }
8972
8973 // Determine if T is a character type for which we guarantee that
8974 // sizeof(T) == 1.
isOneByteCharacterType(QualType T)8975 static bool isOneByteCharacterType(QualType T) {
8976 return T->isCharType() || T->isChar8Type();
8977 }
8978
VisitBuiltinCallExpr(const CallExpr * E,unsigned BuiltinOp)8979 bool PointerExprEvaluator::VisitBuiltinCallExpr(const CallExpr *E,
8980 unsigned BuiltinOp) {
8981 switch (BuiltinOp) {
8982 case Builtin::BI__builtin_addressof:
8983 return evaluateLValue(E->getArg(0), Result);
8984 case Builtin::BI__builtin_assume_aligned: {
8985 // We need to be very careful here because: if the pointer does not have the
8986 // asserted alignment, then the behavior is undefined, and undefined
8987 // behavior is non-constant.
8988 if (!evaluatePointer(E->getArg(0), Result))
8989 return false;
8990
8991 LValue OffsetResult(Result);
8992 APSInt Alignment;
8993 if (!getAlignmentArgument(E->getArg(1), E->getArg(0)->getType(), Info,
8994 Alignment))
8995 return false;
8996 CharUnits Align = CharUnits::fromQuantity(Alignment.getZExtValue());
8997
8998 if (E->getNumArgs() > 2) {
8999 APSInt Offset;
9000 if (!EvaluateInteger(E->getArg(2), Offset, Info))
9001 return false;
9002
9003 int64_t AdditionalOffset = -Offset.getZExtValue();
9004 OffsetResult.Offset += CharUnits::fromQuantity(AdditionalOffset);
9005 }
9006
9007 // If there is a base object, then it must have the correct alignment.
9008 if (OffsetResult.Base) {
9009 CharUnits BaseAlignment = getBaseAlignment(Info, OffsetResult);
9010
9011 if (BaseAlignment < Align) {
9012 Result.Designator.setInvalid();
9013 // FIXME: Add support to Diagnostic for long / long long.
9014 CCEDiag(E->getArg(0),
9015 diag::note_constexpr_baa_insufficient_alignment) << 0
9016 << (unsigned)BaseAlignment.getQuantity()
9017 << (unsigned)Align.getQuantity();
9018 return false;
9019 }
9020 }
9021
9022 // The offset must also have the correct alignment.
9023 if (OffsetResult.Offset.alignTo(Align) != OffsetResult.Offset) {
9024 Result.Designator.setInvalid();
9025
9026 (OffsetResult.Base
9027 ? CCEDiag(E->getArg(0),
9028 diag::note_constexpr_baa_insufficient_alignment) << 1
9029 : CCEDiag(E->getArg(0),
9030 diag::note_constexpr_baa_value_insufficient_alignment))
9031 << (int)OffsetResult.Offset.getQuantity()
9032 << (unsigned)Align.getQuantity();
9033 return false;
9034 }
9035
9036 return true;
9037 }
9038 case Builtin::BI__builtin_align_up:
9039 case Builtin::BI__builtin_align_down: {
9040 if (!evaluatePointer(E->getArg(0), Result))
9041 return false;
9042 APSInt Alignment;
9043 if (!getAlignmentArgument(E->getArg(1), E->getArg(0)->getType(), Info,
9044 Alignment))
9045 return false;
9046 CharUnits BaseAlignment = getBaseAlignment(Info, Result);
9047 CharUnits PtrAlign = BaseAlignment.alignmentAtOffset(Result.Offset);
9048 // For align_up/align_down, we can return the same value if the alignment
9049 // is known to be greater or equal to the requested value.
9050 if (PtrAlign.getQuantity() >= Alignment)
9051 return true;
9052
9053 // The alignment could be greater than the minimum at run-time, so we cannot
9054 // infer much about the resulting pointer value. One case is possible:
9055 // For `_Alignas(32) char buf[N]; __builtin_align_down(&buf[idx], 32)` we
9056 // can infer the correct index if the requested alignment is smaller than
9057 // the base alignment so we can perform the computation on the offset.
9058 if (BaseAlignment.getQuantity() >= Alignment) {
9059 assert(Alignment.getBitWidth() <= 64 &&
9060 "Cannot handle > 64-bit address-space");
9061 uint64_t Alignment64 = Alignment.getZExtValue();
9062 CharUnits NewOffset = CharUnits::fromQuantity(
9063 BuiltinOp == Builtin::BI__builtin_align_down
9064 ? llvm::alignDown(Result.Offset.getQuantity(), Alignment64)
9065 : llvm::alignTo(Result.Offset.getQuantity(), Alignment64));
9066 Result.adjustOffset(NewOffset - Result.Offset);
9067 // TODO: diagnose out-of-bounds values/only allow for arrays?
9068 return true;
9069 }
9070 // Otherwise, we cannot constant-evaluate the result.
9071 Info.FFDiag(E->getArg(0), diag::note_constexpr_alignment_adjust)
9072 << Alignment;
9073 return false;
9074 }
9075 case Builtin::BI__builtin_operator_new:
9076 return HandleOperatorNewCall(Info, E, Result);
9077 case Builtin::BI__builtin_launder:
9078 return evaluatePointer(E->getArg(0), Result);
9079 case Builtin::BIstrchr:
9080 case Builtin::BIwcschr:
9081 case Builtin::BImemchr:
9082 case Builtin::BIwmemchr:
9083 if (Info.getLangOpts().CPlusPlus11)
9084 Info.CCEDiag(E, diag::note_constexpr_invalid_function)
9085 << /*isConstexpr*/0 << /*isConstructor*/0
9086 << (std::string("'") + Info.Ctx.BuiltinInfo.getName(BuiltinOp) + "'");
9087 else
9088 Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr);
9089 LLVM_FALLTHROUGH;
9090 case Builtin::BI__builtin_strchr:
9091 case Builtin::BI__builtin_wcschr:
9092 case Builtin::BI__builtin_memchr:
9093 case Builtin::BI__builtin_char_memchr:
9094 case Builtin::BI__builtin_wmemchr: {
9095 if (!Visit(E->getArg(0)))
9096 return false;
9097 APSInt Desired;
9098 if (!EvaluateInteger(E->getArg(1), Desired, Info))
9099 return false;
9100 uint64_t MaxLength = uint64_t(-1);
9101 if (BuiltinOp != Builtin::BIstrchr &&
9102 BuiltinOp != Builtin::BIwcschr &&
9103 BuiltinOp != Builtin::BI__builtin_strchr &&
9104 BuiltinOp != Builtin::BI__builtin_wcschr) {
9105 APSInt N;
9106 if (!EvaluateInteger(E->getArg(2), N, Info))
9107 return false;
9108 MaxLength = N.getExtValue();
9109 }
9110 // We cannot find the value if there are no candidates to match against.
9111 if (MaxLength == 0u)
9112 return ZeroInitialization(E);
9113 if (!Result.checkNullPointerForFoldAccess(Info, E, AK_Read) ||
9114 Result.Designator.Invalid)
9115 return false;
9116 QualType CharTy = Result.Designator.getType(Info.Ctx);
9117 bool IsRawByte = BuiltinOp == Builtin::BImemchr ||
9118 BuiltinOp == Builtin::BI__builtin_memchr;
9119 assert(IsRawByte ||
9120 Info.Ctx.hasSameUnqualifiedType(
9121 CharTy, E->getArg(0)->getType()->getPointeeType()));
9122 // Pointers to const void may point to objects of incomplete type.
9123 if (IsRawByte && CharTy->isIncompleteType()) {
9124 Info.FFDiag(E, diag::note_constexpr_ltor_incomplete_type) << CharTy;
9125 return false;
9126 }
9127 // Give up on byte-oriented matching against multibyte elements.
9128 // FIXME: We can compare the bytes in the correct order.
9129 if (IsRawByte && !isOneByteCharacterType(CharTy)) {
9130 Info.FFDiag(E, diag::note_constexpr_memchr_unsupported)
9131 << (std::string("'") + Info.Ctx.BuiltinInfo.getName(BuiltinOp) + "'")
9132 << CharTy;
9133 return false;
9134 }
9135 // Figure out what value we're actually looking for (after converting to
9136 // the corresponding unsigned type if necessary).
9137 uint64_t DesiredVal;
9138 bool StopAtNull = false;
9139 switch (BuiltinOp) {
9140 case Builtin::BIstrchr:
9141 case Builtin::BI__builtin_strchr:
9142 // strchr compares directly to the passed integer, and therefore
9143 // always fails if given an int that is not a char.
9144 if (!APSInt::isSameValue(HandleIntToIntCast(Info, E, CharTy,
9145 E->getArg(1)->getType(),
9146 Desired),
9147 Desired))
9148 return ZeroInitialization(E);
9149 StopAtNull = true;
9150 LLVM_FALLTHROUGH;
9151 case Builtin::BImemchr:
9152 case Builtin::BI__builtin_memchr:
9153 case Builtin::BI__builtin_char_memchr:
9154 // memchr compares by converting both sides to unsigned char. That's also
9155 // correct for strchr if we get this far (to cope with plain char being
9156 // unsigned in the strchr case).
9157 DesiredVal = Desired.trunc(Info.Ctx.getCharWidth()).getZExtValue();
9158 break;
9159
9160 case Builtin::BIwcschr:
9161 case Builtin::BI__builtin_wcschr:
9162 StopAtNull = true;
9163 LLVM_FALLTHROUGH;
9164 case Builtin::BIwmemchr:
9165 case Builtin::BI__builtin_wmemchr:
9166 // wcschr and wmemchr are given a wchar_t to look for. Just use it.
9167 DesiredVal = Desired.getZExtValue();
9168 break;
9169 }
9170
9171 for (; MaxLength; --MaxLength) {
9172 APValue Char;
9173 if (!handleLValueToRValueConversion(Info, E, CharTy, Result, Char) ||
9174 !Char.isInt())
9175 return false;
9176 if (Char.getInt().getZExtValue() == DesiredVal)
9177 return true;
9178 if (StopAtNull && !Char.getInt())
9179 break;
9180 if (!HandleLValueArrayAdjustment(Info, E, Result, CharTy, 1))
9181 return false;
9182 }
9183 // Not found: return nullptr.
9184 return ZeroInitialization(E);
9185 }
9186
9187 case Builtin::BImemcpy:
9188 case Builtin::BImemmove:
9189 case Builtin::BIwmemcpy:
9190 case Builtin::BIwmemmove:
9191 if (Info.getLangOpts().CPlusPlus11)
9192 Info.CCEDiag(E, diag::note_constexpr_invalid_function)
9193 << /*isConstexpr*/0 << /*isConstructor*/0
9194 << (std::string("'") + Info.Ctx.BuiltinInfo.getName(BuiltinOp) + "'");
9195 else
9196 Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr);
9197 LLVM_FALLTHROUGH;
9198 case Builtin::BI__builtin_memcpy:
9199 case Builtin::BI__builtin_memmove:
9200 case Builtin::BI__builtin_wmemcpy:
9201 case Builtin::BI__builtin_wmemmove: {
9202 bool WChar = BuiltinOp == Builtin::BIwmemcpy ||
9203 BuiltinOp == Builtin::BIwmemmove ||
9204 BuiltinOp == Builtin::BI__builtin_wmemcpy ||
9205 BuiltinOp == Builtin::BI__builtin_wmemmove;
9206 bool Move = BuiltinOp == Builtin::BImemmove ||
9207 BuiltinOp == Builtin::BIwmemmove ||
9208 BuiltinOp == Builtin::BI__builtin_memmove ||
9209 BuiltinOp == Builtin::BI__builtin_wmemmove;
9210
9211 // The result of mem* is the first argument.
9212 if (!Visit(E->getArg(0)))
9213 return false;
9214 LValue Dest = Result;
9215
9216 LValue Src;
9217 if (!EvaluatePointer(E->getArg(1), Src, Info))
9218 return false;
9219
9220 APSInt N;
9221 if (!EvaluateInteger(E->getArg(2), N, Info))
9222 return false;
9223 assert(!N.isSigned() && "memcpy and friends take an unsigned size");
9224
9225 // If the size is zero, we treat this as always being a valid no-op.
9226 // (Even if one of the src and dest pointers is null.)
9227 if (!N)
9228 return true;
9229
9230 // Otherwise, if either of the operands is null, we can't proceed. Don't
9231 // try to determine the type of the copied objects, because there aren't
9232 // any.
9233 if (!Src.Base || !Dest.Base) {
9234 APValue Val;
9235 (!Src.Base ? Src : Dest).moveInto(Val);
9236 Info.FFDiag(E, diag::note_constexpr_memcpy_null)
9237 << Move << WChar << !!Src.Base
9238 << Val.getAsString(Info.Ctx, E->getArg(0)->getType());
9239 return false;
9240 }
9241 if (Src.Designator.Invalid || Dest.Designator.Invalid)
9242 return false;
9243
9244 // We require that Src and Dest are both pointers to arrays of
9245 // trivially-copyable type. (For the wide version, the designator will be
9246 // invalid if the designated object is not a wchar_t.)
9247 QualType T = Dest.Designator.getType(Info.Ctx);
9248 QualType SrcT = Src.Designator.getType(Info.Ctx);
9249 if (!Info.Ctx.hasSameUnqualifiedType(T, SrcT)) {
9250 // FIXME: Consider using our bit_cast implementation to support this.
9251 Info.FFDiag(E, diag::note_constexpr_memcpy_type_pun) << Move << SrcT << T;
9252 return false;
9253 }
9254 if (T->isIncompleteType()) {
9255 Info.FFDiag(E, diag::note_constexpr_memcpy_incomplete_type) << Move << T;
9256 return false;
9257 }
9258 if (!T.isTriviallyCopyableType(Info.Ctx)) {
9259 Info.FFDiag(E, diag::note_constexpr_memcpy_nontrivial) << Move << T;
9260 return false;
9261 }
9262
9263 // Figure out how many T's we're copying.
9264 uint64_t TSize = Info.Ctx.getTypeSizeInChars(T).getQuantity();
9265 if (!WChar) {
9266 uint64_t Remainder;
9267 llvm::APInt OrigN = N;
9268 llvm::APInt::udivrem(OrigN, TSize, N, Remainder);
9269 if (Remainder) {
9270 Info.FFDiag(E, diag::note_constexpr_memcpy_unsupported)
9271 << Move << WChar << 0 << T << toString(OrigN, 10, /*Signed*/false)
9272 << (unsigned)TSize;
9273 return false;
9274 }
9275 }
9276
9277 // Check that the copying will remain within the arrays, just so that we
9278 // can give a more meaningful diagnostic. This implicitly also checks that
9279 // N fits into 64 bits.
9280 uint64_t RemainingSrcSize = Src.Designator.validIndexAdjustments().second;
9281 uint64_t RemainingDestSize = Dest.Designator.validIndexAdjustments().second;
9282 if (N.ugt(RemainingSrcSize) || N.ugt(RemainingDestSize)) {
9283 Info.FFDiag(E, diag::note_constexpr_memcpy_unsupported)
9284 << Move << WChar << (N.ugt(RemainingSrcSize) ? 1 : 2) << T
9285 << toString(N, 10, /*Signed*/false);
9286 return false;
9287 }
9288 uint64_t NElems = N.getZExtValue();
9289 uint64_t NBytes = NElems * TSize;
9290
9291 // Check for overlap.
9292 int Direction = 1;
9293 if (HasSameBase(Src, Dest)) {
9294 uint64_t SrcOffset = Src.getLValueOffset().getQuantity();
9295 uint64_t DestOffset = Dest.getLValueOffset().getQuantity();
9296 if (DestOffset >= SrcOffset && DestOffset - SrcOffset < NBytes) {
9297 // Dest is inside the source region.
9298 if (!Move) {
9299 Info.FFDiag(E, diag::note_constexpr_memcpy_overlap) << WChar;
9300 return false;
9301 }
9302 // For memmove and friends, copy backwards.
9303 if (!HandleLValueArrayAdjustment(Info, E, Src, T, NElems - 1) ||
9304 !HandleLValueArrayAdjustment(Info, E, Dest, T, NElems - 1))
9305 return false;
9306 Direction = -1;
9307 } else if (!Move && SrcOffset >= DestOffset &&
9308 SrcOffset - DestOffset < NBytes) {
9309 // Src is inside the destination region for memcpy: invalid.
9310 Info.FFDiag(E, diag::note_constexpr_memcpy_overlap) << WChar;
9311 return false;
9312 }
9313 }
9314
9315 while (true) {
9316 APValue Val;
9317 // FIXME: Set WantObjectRepresentation to true if we're copying a
9318 // char-like type?
9319 if (!handleLValueToRValueConversion(Info, E, T, Src, Val) ||
9320 !handleAssignment(Info, E, Dest, T, Val))
9321 return false;
9322 // Do not iterate past the last element; if we're copying backwards, that
9323 // might take us off the start of the array.
9324 if (--NElems == 0)
9325 return true;
9326 if (!HandleLValueArrayAdjustment(Info, E, Src, T, Direction) ||
9327 !HandleLValueArrayAdjustment(Info, E, Dest, T, Direction))
9328 return false;
9329 }
9330 }
9331
9332 default:
9333 break;
9334 }
9335
9336 return visitNonBuiltinCallExpr(E);
9337 }
9338
9339 static bool EvaluateArrayNewInitList(EvalInfo &Info, LValue &This,
9340 APValue &Result, const InitListExpr *ILE,
9341 QualType AllocType);
9342 static bool EvaluateArrayNewConstructExpr(EvalInfo &Info, LValue &This,
9343 APValue &Result,
9344 const CXXConstructExpr *CCE,
9345 QualType AllocType);
9346
VisitCXXNewExpr(const CXXNewExpr * E)9347 bool PointerExprEvaluator::VisitCXXNewExpr(const CXXNewExpr *E) {
9348 if (!Info.getLangOpts().CPlusPlus20)
9349 Info.CCEDiag(E, diag::note_constexpr_new);
9350
9351 // We cannot speculatively evaluate a delete expression.
9352 if (Info.SpeculativeEvaluationDepth)
9353 return false;
9354
9355 FunctionDecl *OperatorNew = E->getOperatorNew();
9356
9357 bool IsNothrow = false;
9358 bool IsPlacement = false;
9359 if (OperatorNew->isReservedGlobalPlacementOperator() &&
9360 Info.CurrentCall->isStdFunction() && !E->isArray()) {
9361 // FIXME Support array placement new.
9362 assert(E->getNumPlacementArgs() == 1);
9363 if (!EvaluatePointer(E->getPlacementArg(0), Result, Info))
9364 return false;
9365 if (Result.Designator.Invalid)
9366 return false;
9367 IsPlacement = true;
9368 } else if (!OperatorNew->isReplaceableGlobalAllocationFunction()) {
9369 Info.FFDiag(E, diag::note_constexpr_new_non_replaceable)
9370 << isa<CXXMethodDecl>(OperatorNew) << OperatorNew;
9371 return false;
9372 } else if (E->getNumPlacementArgs()) {
9373 // The only new-placement list we support is of the form (std::nothrow).
9374 //
9375 // FIXME: There is no restriction on this, but it's not clear that any
9376 // other form makes any sense. We get here for cases such as:
9377 //
9378 // new (std::align_val_t{N}) X(int)
9379 //
9380 // (which should presumably be valid only if N is a multiple of
9381 // alignof(int), and in any case can't be deallocated unless N is
9382 // alignof(X) and X has new-extended alignment).
9383 if (E->getNumPlacementArgs() != 1 ||
9384 !E->getPlacementArg(0)->getType()->isNothrowT())
9385 return Error(E, diag::note_constexpr_new_placement);
9386
9387 LValue Nothrow;
9388 if (!EvaluateLValue(E->getPlacementArg(0), Nothrow, Info))
9389 return false;
9390 IsNothrow = true;
9391 }
9392
9393 const Expr *Init = E->getInitializer();
9394 const InitListExpr *ResizedArrayILE = nullptr;
9395 const CXXConstructExpr *ResizedArrayCCE = nullptr;
9396 bool ValueInit = false;
9397
9398 QualType AllocType = E->getAllocatedType();
9399 if (Optional<const Expr*> ArraySize = E->getArraySize()) {
9400 const Expr *Stripped = *ArraySize;
9401 for (; auto *ICE = dyn_cast<ImplicitCastExpr>(Stripped);
9402 Stripped = ICE->getSubExpr())
9403 if (ICE->getCastKind() != CK_NoOp &&
9404 ICE->getCastKind() != CK_IntegralCast)
9405 break;
9406
9407 llvm::APSInt ArrayBound;
9408 if (!EvaluateInteger(Stripped, ArrayBound, Info))
9409 return false;
9410
9411 // C++ [expr.new]p9:
9412 // The expression is erroneous if:
9413 // -- [...] its value before converting to size_t [or] applying the
9414 // second standard conversion sequence is less than zero
9415 if (ArrayBound.isSigned() && ArrayBound.isNegative()) {
9416 if (IsNothrow)
9417 return ZeroInitialization(E);
9418
9419 Info.FFDiag(*ArraySize, diag::note_constexpr_new_negative)
9420 << ArrayBound << (*ArraySize)->getSourceRange();
9421 return false;
9422 }
9423
9424 // -- its value is such that the size of the allocated object would
9425 // exceed the implementation-defined limit
9426 if (ConstantArrayType::getNumAddressingBits(Info.Ctx, AllocType,
9427 ArrayBound) >
9428 ConstantArrayType::getMaxSizeBits(Info.Ctx)) {
9429 if (IsNothrow)
9430 return ZeroInitialization(E);
9431
9432 Info.FFDiag(*ArraySize, diag::note_constexpr_new_too_large)
9433 << ArrayBound << (*ArraySize)->getSourceRange();
9434 return false;
9435 }
9436
9437 // -- the new-initializer is a braced-init-list and the number of
9438 // array elements for which initializers are provided [...]
9439 // exceeds the number of elements to initialize
9440 if (!Init) {
9441 // No initialization is performed.
9442 } else if (isa<CXXScalarValueInitExpr>(Init) ||
9443 isa<ImplicitValueInitExpr>(Init)) {
9444 ValueInit = true;
9445 } else if (auto *CCE = dyn_cast<CXXConstructExpr>(Init)) {
9446 ResizedArrayCCE = CCE;
9447 } else {
9448 auto *CAT = Info.Ctx.getAsConstantArrayType(Init->getType());
9449 assert(CAT && "unexpected type for array initializer");
9450
9451 unsigned Bits =
9452 std::max(CAT->getSize().getBitWidth(), ArrayBound.getBitWidth());
9453 llvm::APInt InitBound = CAT->getSize().zextOrSelf(Bits);
9454 llvm::APInt AllocBound = ArrayBound.zextOrSelf(Bits);
9455 if (InitBound.ugt(AllocBound)) {
9456 if (IsNothrow)
9457 return ZeroInitialization(E);
9458
9459 Info.FFDiag(*ArraySize, diag::note_constexpr_new_too_small)
9460 << toString(AllocBound, 10, /*Signed=*/false)
9461 << toString(InitBound, 10, /*Signed=*/false)
9462 << (*ArraySize)->getSourceRange();
9463 return false;
9464 }
9465
9466 // If the sizes differ, we must have an initializer list, and we need
9467 // special handling for this case when we initialize.
9468 if (InitBound != AllocBound)
9469 ResizedArrayILE = cast<InitListExpr>(Init);
9470 }
9471
9472 AllocType = Info.Ctx.getConstantArrayType(AllocType, ArrayBound, nullptr,
9473 ArrayType::Normal, 0);
9474 } else {
9475 assert(!AllocType->isArrayType() &&
9476 "array allocation with non-array new");
9477 }
9478
9479 APValue *Val;
9480 if (IsPlacement) {
9481 AccessKinds AK = AK_Construct;
9482 struct FindObjectHandler {
9483 EvalInfo &Info;
9484 const Expr *E;
9485 QualType AllocType;
9486 const AccessKinds AccessKind;
9487 APValue *Value;
9488
9489 typedef bool result_type;
9490 bool failed() { return false; }
9491 bool found(APValue &Subobj, QualType SubobjType) {
9492 // FIXME: Reject the cases where [basic.life]p8 would not permit the
9493 // old name of the object to be used to name the new object.
9494 if (!Info.Ctx.hasSameUnqualifiedType(SubobjType, AllocType)) {
9495 Info.FFDiag(E, diag::note_constexpr_placement_new_wrong_type) <<
9496 SubobjType << AllocType;
9497 return false;
9498 }
9499 Value = &Subobj;
9500 return true;
9501 }
9502 bool found(APSInt &Value, QualType SubobjType) {
9503 Info.FFDiag(E, diag::note_constexpr_construct_complex_elem);
9504 return false;
9505 }
9506 bool found(APFloat &Value, QualType SubobjType) {
9507 Info.FFDiag(E, diag::note_constexpr_construct_complex_elem);
9508 return false;
9509 }
9510 } Handler = {Info, E, AllocType, AK, nullptr};
9511
9512 CompleteObject Obj = findCompleteObject(Info, E, AK, Result, AllocType);
9513 if (!Obj || !findSubobject(Info, E, Obj, Result.Designator, Handler))
9514 return false;
9515
9516 Val = Handler.Value;
9517
9518 // [basic.life]p1:
9519 // The lifetime of an object o of type T ends when [...] the storage
9520 // which the object occupies is [...] reused by an object that is not
9521 // nested within o (6.6.2).
9522 *Val = APValue();
9523 } else {
9524 // Perform the allocation and obtain a pointer to the resulting object.
9525 Val = Info.createHeapAlloc(E, AllocType, Result);
9526 if (!Val)
9527 return false;
9528 }
9529
9530 if (ValueInit) {
9531 ImplicitValueInitExpr VIE(AllocType);
9532 if (!EvaluateInPlace(*Val, Info, Result, &VIE))
9533 return false;
9534 } else if (ResizedArrayILE) {
9535 if (!EvaluateArrayNewInitList(Info, Result, *Val, ResizedArrayILE,
9536 AllocType))
9537 return false;
9538 } else if (ResizedArrayCCE) {
9539 if (!EvaluateArrayNewConstructExpr(Info, Result, *Val, ResizedArrayCCE,
9540 AllocType))
9541 return false;
9542 } else if (Init) {
9543 if (!EvaluateInPlace(*Val, Info, Result, Init))
9544 return false;
9545 } else if (!getDefaultInitValue(AllocType, *Val)) {
9546 return false;
9547 }
9548
9549 // Array new returns a pointer to the first element, not a pointer to the
9550 // array.
9551 if (auto *AT = AllocType->getAsArrayTypeUnsafe())
9552 Result.addArray(Info, E, cast<ConstantArrayType>(AT));
9553
9554 return true;
9555 }
9556 //===----------------------------------------------------------------------===//
9557 // Member Pointer Evaluation
9558 //===----------------------------------------------------------------------===//
9559
9560 namespace {
9561 class MemberPointerExprEvaluator
9562 : public ExprEvaluatorBase<MemberPointerExprEvaluator> {
9563 MemberPtr &Result;
9564
Success(const ValueDecl * D)9565 bool Success(const ValueDecl *D) {
9566 Result = MemberPtr(D);
9567 return true;
9568 }
9569 public:
9570
MemberPointerExprEvaluator(EvalInfo & Info,MemberPtr & Result)9571 MemberPointerExprEvaluator(EvalInfo &Info, MemberPtr &Result)
9572 : ExprEvaluatorBaseTy(Info), Result(Result) {}
9573
Success(const APValue & V,const Expr * E)9574 bool Success(const APValue &V, const Expr *E) {
9575 Result.setFrom(V);
9576 return true;
9577 }
ZeroInitialization(const Expr * E)9578 bool ZeroInitialization(const Expr *E) {
9579 return Success((const ValueDecl*)nullptr);
9580 }
9581
9582 bool VisitCastExpr(const CastExpr *E);
9583 bool VisitUnaryAddrOf(const UnaryOperator *E);
9584 };
9585 } // end anonymous namespace
9586
EvaluateMemberPointer(const Expr * E,MemberPtr & Result,EvalInfo & Info)9587 static bool EvaluateMemberPointer(const Expr *E, MemberPtr &Result,
9588 EvalInfo &Info) {
9589 assert(!E->isValueDependent());
9590 assert(E->isPRValue() && E->getType()->isMemberPointerType());
9591 return MemberPointerExprEvaluator(Info, Result).Visit(E);
9592 }
9593
VisitCastExpr(const CastExpr * E)9594 bool MemberPointerExprEvaluator::VisitCastExpr(const CastExpr *E) {
9595 switch (E->getCastKind()) {
9596 default:
9597 return ExprEvaluatorBaseTy::VisitCastExpr(E);
9598
9599 case CK_NullToMemberPointer:
9600 VisitIgnoredValue(E->getSubExpr());
9601 return ZeroInitialization(E);
9602
9603 case CK_BaseToDerivedMemberPointer: {
9604 if (!Visit(E->getSubExpr()))
9605 return false;
9606 if (E->path_empty())
9607 return true;
9608 // Base-to-derived member pointer casts store the path in derived-to-base
9609 // order, so iterate backwards. The CXXBaseSpecifier also provides us with
9610 // the wrong end of the derived->base arc, so stagger the path by one class.
9611 typedef std::reverse_iterator<CastExpr::path_const_iterator> ReverseIter;
9612 for (ReverseIter PathI(E->path_end() - 1), PathE(E->path_begin());
9613 PathI != PathE; ++PathI) {
9614 assert(!(*PathI)->isVirtual() && "memptr cast through vbase");
9615 const CXXRecordDecl *Derived = (*PathI)->getType()->getAsCXXRecordDecl();
9616 if (!Result.castToDerived(Derived))
9617 return Error(E);
9618 }
9619 const Type *FinalTy = E->getType()->castAs<MemberPointerType>()->getClass();
9620 if (!Result.castToDerived(FinalTy->getAsCXXRecordDecl()))
9621 return Error(E);
9622 return true;
9623 }
9624
9625 case CK_DerivedToBaseMemberPointer:
9626 if (!Visit(E->getSubExpr()))
9627 return false;
9628 for (CastExpr::path_const_iterator PathI = E->path_begin(),
9629 PathE = E->path_end(); PathI != PathE; ++PathI) {
9630 assert(!(*PathI)->isVirtual() && "memptr cast through vbase");
9631 const CXXRecordDecl *Base = (*PathI)->getType()->getAsCXXRecordDecl();
9632 if (!Result.castToBase(Base))
9633 return Error(E);
9634 }
9635 return true;
9636 }
9637 }
9638
VisitUnaryAddrOf(const UnaryOperator * E)9639 bool MemberPointerExprEvaluator::VisitUnaryAddrOf(const UnaryOperator *E) {
9640 // C++11 [expr.unary.op]p3 has very strict rules on how the address of a
9641 // member can be formed.
9642 return Success(cast<DeclRefExpr>(E->getSubExpr())->getDecl());
9643 }
9644
9645 //===----------------------------------------------------------------------===//
9646 // Record Evaluation
9647 //===----------------------------------------------------------------------===//
9648
9649 namespace {
9650 class RecordExprEvaluator
9651 : public ExprEvaluatorBase<RecordExprEvaluator> {
9652 const LValue &This;
9653 APValue &Result;
9654 public:
9655
RecordExprEvaluator(EvalInfo & info,const LValue & This,APValue & Result)9656 RecordExprEvaluator(EvalInfo &info, const LValue &This, APValue &Result)
9657 : ExprEvaluatorBaseTy(info), This(This), Result(Result) {}
9658
Success(const APValue & V,const Expr * E)9659 bool Success(const APValue &V, const Expr *E) {
9660 Result = V;
9661 return true;
9662 }
ZeroInitialization(const Expr * E)9663 bool ZeroInitialization(const Expr *E) {
9664 return ZeroInitialization(E, E->getType());
9665 }
9666 bool ZeroInitialization(const Expr *E, QualType T);
9667
VisitCallExpr(const CallExpr * E)9668 bool VisitCallExpr(const CallExpr *E) {
9669 return handleCallExpr(E, Result, &This);
9670 }
9671 bool VisitCastExpr(const CastExpr *E);
9672 bool VisitInitListExpr(const InitListExpr *E);
VisitCXXConstructExpr(const CXXConstructExpr * E)9673 bool VisitCXXConstructExpr(const CXXConstructExpr *E) {
9674 return VisitCXXConstructExpr(E, E->getType());
9675 }
9676 bool VisitLambdaExpr(const LambdaExpr *E);
9677 bool VisitCXXInheritedCtorInitExpr(const CXXInheritedCtorInitExpr *E);
9678 bool VisitCXXConstructExpr(const CXXConstructExpr *E, QualType T);
9679 bool VisitCXXStdInitializerListExpr(const CXXStdInitializerListExpr *E);
9680 bool VisitBinCmp(const BinaryOperator *E);
9681 };
9682 }
9683
9684 /// Perform zero-initialization on an object of non-union class type.
9685 /// C++11 [dcl.init]p5:
9686 /// To zero-initialize an object or reference of type T means:
9687 /// [...]
9688 /// -- if T is a (possibly cv-qualified) non-union class type,
9689 /// each non-static data member and each base-class subobject is
9690 /// zero-initialized
HandleClassZeroInitialization(EvalInfo & Info,const Expr * E,const RecordDecl * RD,const LValue & This,APValue & Result)9691 static bool HandleClassZeroInitialization(EvalInfo &Info, const Expr *E,
9692 const RecordDecl *RD,
9693 const LValue &This, APValue &Result) {
9694 assert(!RD->isUnion() && "Expected non-union class type");
9695 const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(RD);
9696 Result = APValue(APValue::UninitStruct(), CD ? CD->getNumBases() : 0,
9697 std::distance(RD->field_begin(), RD->field_end()));
9698
9699 if (RD->isInvalidDecl()) return false;
9700 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
9701
9702 if (CD) {
9703 unsigned Index = 0;
9704 for (CXXRecordDecl::base_class_const_iterator I = CD->bases_begin(),
9705 End = CD->bases_end(); I != End; ++I, ++Index) {
9706 const CXXRecordDecl *Base = I->getType()->getAsCXXRecordDecl();
9707 LValue Subobject = This;
9708 if (!HandleLValueDirectBase(Info, E, Subobject, CD, Base, &Layout))
9709 return false;
9710 if (!HandleClassZeroInitialization(Info, E, Base, Subobject,
9711 Result.getStructBase(Index)))
9712 return false;
9713 }
9714 }
9715
9716 for (const auto *I : RD->fields()) {
9717 // -- if T is a reference type, no initialization is performed.
9718 if (I->isUnnamedBitfield() || I->getType()->isReferenceType())
9719 continue;
9720
9721 LValue Subobject = This;
9722 if (!HandleLValueMember(Info, E, Subobject, I, &Layout))
9723 return false;
9724
9725 ImplicitValueInitExpr VIE(I->getType());
9726 if (!EvaluateInPlace(
9727 Result.getStructField(I->getFieldIndex()), Info, Subobject, &VIE))
9728 return false;
9729 }
9730
9731 return true;
9732 }
9733
ZeroInitialization(const Expr * E,QualType T)9734 bool RecordExprEvaluator::ZeroInitialization(const Expr *E, QualType T) {
9735 const RecordDecl *RD = T->castAs<RecordType>()->getDecl();
9736 if (RD->isInvalidDecl()) return false;
9737 if (RD->isUnion()) {
9738 // C++11 [dcl.init]p5: If T is a (possibly cv-qualified) union type, the
9739 // object's first non-static named data member is zero-initialized
9740 RecordDecl::field_iterator I = RD->field_begin();
9741 while (I != RD->field_end() && (*I)->isUnnamedBitfield())
9742 ++I;
9743 if (I == RD->field_end()) {
9744 Result = APValue((const FieldDecl*)nullptr);
9745 return true;
9746 }
9747
9748 LValue Subobject = This;
9749 if (!HandleLValueMember(Info, E, Subobject, *I))
9750 return false;
9751 Result = APValue(*I);
9752 ImplicitValueInitExpr VIE(I->getType());
9753 return EvaluateInPlace(Result.getUnionValue(), Info, Subobject, &VIE);
9754 }
9755
9756 if (isa<CXXRecordDecl>(RD) && cast<CXXRecordDecl>(RD)->getNumVBases()) {
9757 Info.FFDiag(E, diag::note_constexpr_virtual_base) << RD;
9758 return false;
9759 }
9760
9761 return HandleClassZeroInitialization(Info, E, RD, This, Result);
9762 }
9763
VisitCastExpr(const CastExpr * E)9764 bool RecordExprEvaluator::VisitCastExpr(const CastExpr *E) {
9765 switch (E->getCastKind()) {
9766 default:
9767 return ExprEvaluatorBaseTy::VisitCastExpr(E);
9768
9769 case CK_ConstructorConversion:
9770 return Visit(E->getSubExpr());
9771
9772 case CK_DerivedToBase:
9773 case CK_UncheckedDerivedToBase: {
9774 APValue DerivedObject;
9775 if (!Evaluate(DerivedObject, Info, E->getSubExpr()))
9776 return false;
9777 if (!DerivedObject.isStruct())
9778 return Error(E->getSubExpr());
9779
9780 // Derived-to-base rvalue conversion: just slice off the derived part.
9781 APValue *Value = &DerivedObject;
9782 const CXXRecordDecl *RD = E->getSubExpr()->getType()->getAsCXXRecordDecl();
9783 for (CastExpr::path_const_iterator PathI = E->path_begin(),
9784 PathE = E->path_end(); PathI != PathE; ++PathI) {
9785 assert(!(*PathI)->isVirtual() && "record rvalue with virtual base");
9786 const CXXRecordDecl *Base = (*PathI)->getType()->getAsCXXRecordDecl();
9787 Value = &Value->getStructBase(getBaseIndex(RD, Base));
9788 RD = Base;
9789 }
9790 Result = *Value;
9791 return true;
9792 }
9793 }
9794 }
9795
VisitInitListExpr(const InitListExpr * E)9796 bool RecordExprEvaluator::VisitInitListExpr(const InitListExpr *E) {
9797 if (E->isTransparent())
9798 return Visit(E->getInit(0));
9799
9800 const RecordDecl *RD = E->getType()->castAs<RecordType>()->getDecl();
9801 if (RD->isInvalidDecl()) return false;
9802 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
9803 auto *CXXRD = dyn_cast<CXXRecordDecl>(RD);
9804
9805 EvalInfo::EvaluatingConstructorRAII EvalObj(
9806 Info,
9807 ObjectUnderConstruction{This.getLValueBase(), This.Designator.Entries},
9808 CXXRD && CXXRD->getNumBases());
9809
9810 if (RD->isUnion()) {
9811 const FieldDecl *Field = E->getInitializedFieldInUnion();
9812 Result = APValue(Field);
9813 if (!Field)
9814 return true;
9815
9816 // If the initializer list for a union does not contain any elements, the
9817 // first element of the union is value-initialized.
9818 // FIXME: The element should be initialized from an initializer list.
9819 // Is this difference ever observable for initializer lists which
9820 // we don't build?
9821 ImplicitValueInitExpr VIE(Field->getType());
9822 const Expr *InitExpr = E->getNumInits() ? E->getInit(0) : &VIE;
9823
9824 LValue Subobject = This;
9825 if (!HandleLValueMember(Info, InitExpr, Subobject, Field, &Layout))
9826 return false;
9827
9828 // Temporarily override This, in case there's a CXXDefaultInitExpr in here.
9829 ThisOverrideRAII ThisOverride(*Info.CurrentCall, &This,
9830 isa<CXXDefaultInitExpr>(InitExpr));
9831
9832 if (EvaluateInPlace(Result.getUnionValue(), Info, Subobject, InitExpr)) {
9833 if (Field->isBitField())
9834 return truncateBitfieldValue(Info, InitExpr, Result.getUnionValue(),
9835 Field);
9836 return true;
9837 }
9838
9839 return false;
9840 }
9841
9842 if (!Result.hasValue())
9843 Result = APValue(APValue::UninitStruct(), CXXRD ? CXXRD->getNumBases() : 0,
9844 std::distance(RD->field_begin(), RD->field_end()));
9845 unsigned ElementNo = 0;
9846 bool Success = true;
9847
9848 // Initialize base classes.
9849 if (CXXRD && CXXRD->getNumBases()) {
9850 for (const auto &Base : CXXRD->bases()) {
9851 assert(ElementNo < E->getNumInits() && "missing init for base class");
9852 const Expr *Init = E->getInit(ElementNo);
9853
9854 LValue Subobject = This;
9855 if (!HandleLValueBase(Info, Init, Subobject, CXXRD, &Base))
9856 return false;
9857
9858 APValue &FieldVal = Result.getStructBase(ElementNo);
9859 if (!EvaluateInPlace(FieldVal, Info, Subobject, Init)) {
9860 if (!Info.noteFailure())
9861 return false;
9862 Success = false;
9863 }
9864 ++ElementNo;
9865 }
9866
9867 EvalObj.finishedConstructingBases();
9868 }
9869
9870 // Initialize members.
9871 for (const auto *Field : RD->fields()) {
9872 // Anonymous bit-fields are not considered members of the class for
9873 // purposes of aggregate initialization.
9874 if (Field->isUnnamedBitfield())
9875 continue;
9876
9877 LValue Subobject = This;
9878
9879 bool HaveInit = ElementNo < E->getNumInits();
9880
9881 // FIXME: Diagnostics here should point to the end of the initializer
9882 // list, not the start.
9883 if (!HandleLValueMember(Info, HaveInit ? E->getInit(ElementNo) : E,
9884 Subobject, Field, &Layout))
9885 return false;
9886
9887 // Perform an implicit value-initialization for members beyond the end of
9888 // the initializer list.
9889 ImplicitValueInitExpr VIE(HaveInit ? Info.Ctx.IntTy : Field->getType());
9890 const Expr *Init = HaveInit ? E->getInit(ElementNo++) : &VIE;
9891
9892 // Temporarily override This, in case there's a CXXDefaultInitExpr in here.
9893 ThisOverrideRAII ThisOverride(*Info.CurrentCall, &This,
9894 isa<CXXDefaultInitExpr>(Init));
9895
9896 APValue &FieldVal = Result.getStructField(Field->getFieldIndex());
9897 if (!EvaluateInPlace(FieldVal, Info, Subobject, Init) ||
9898 (Field->isBitField() && !truncateBitfieldValue(Info, Init,
9899 FieldVal, Field))) {
9900 if (!Info.noteFailure())
9901 return false;
9902 Success = false;
9903 }
9904 }
9905
9906 EvalObj.finishedConstructingFields();
9907
9908 return Success;
9909 }
9910
VisitCXXConstructExpr(const CXXConstructExpr * E,QualType T)9911 bool RecordExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E,
9912 QualType T) {
9913 // Note that E's type is not necessarily the type of our class here; we might
9914 // be initializing an array element instead.
9915 const CXXConstructorDecl *FD = E->getConstructor();
9916 if (FD->isInvalidDecl() || FD->getParent()->isInvalidDecl()) return false;
9917
9918 bool ZeroInit = E->requiresZeroInitialization();
9919 if (CheckTrivialDefaultConstructor(Info, E->getExprLoc(), FD, ZeroInit)) {
9920 // If we've already performed zero-initialization, we're already done.
9921 if (Result.hasValue())
9922 return true;
9923
9924 if (ZeroInit)
9925 return ZeroInitialization(E, T);
9926
9927 return getDefaultInitValue(T, Result);
9928 }
9929
9930 const FunctionDecl *Definition = nullptr;
9931 auto Body = FD->getBody(Definition);
9932
9933 if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition, Body))
9934 return false;
9935
9936 // Avoid materializing a temporary for an elidable copy/move constructor.
9937 if (E->isElidable() && !ZeroInit) {
9938 // FIXME: This only handles the simplest case, where the source object
9939 // is passed directly as the first argument to the constructor.
9940 // This should also handle stepping though implicit casts and
9941 // and conversion sequences which involve two steps, with a
9942 // conversion operator followed by a converting constructor.
9943 const Expr *SrcObj = E->getArg(0);
9944 assert(SrcObj->isTemporaryObject(Info.Ctx, FD->getParent()));
9945 assert(Info.Ctx.hasSameUnqualifiedType(E->getType(), SrcObj->getType()));
9946 if (const MaterializeTemporaryExpr *ME =
9947 dyn_cast<MaterializeTemporaryExpr>(SrcObj))
9948 return Visit(ME->getSubExpr());
9949 }
9950
9951 if (ZeroInit && !ZeroInitialization(E, T))
9952 return false;
9953
9954 auto Args = llvm::makeArrayRef(E->getArgs(), E->getNumArgs());
9955 return HandleConstructorCall(E, This, Args,
9956 cast<CXXConstructorDecl>(Definition), Info,
9957 Result);
9958 }
9959
VisitCXXInheritedCtorInitExpr(const CXXInheritedCtorInitExpr * E)9960 bool RecordExprEvaluator::VisitCXXInheritedCtorInitExpr(
9961 const CXXInheritedCtorInitExpr *E) {
9962 if (!Info.CurrentCall) {
9963 assert(Info.checkingPotentialConstantExpression());
9964 return false;
9965 }
9966
9967 const CXXConstructorDecl *FD = E->getConstructor();
9968 if (FD->isInvalidDecl() || FD->getParent()->isInvalidDecl())
9969 return false;
9970
9971 const FunctionDecl *Definition = nullptr;
9972 auto Body = FD->getBody(Definition);
9973
9974 if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition, Body))
9975 return false;
9976
9977 return HandleConstructorCall(E, This, Info.CurrentCall->Arguments,
9978 cast<CXXConstructorDecl>(Definition), Info,
9979 Result);
9980 }
9981
VisitCXXStdInitializerListExpr(const CXXStdInitializerListExpr * E)9982 bool RecordExprEvaluator::VisitCXXStdInitializerListExpr(
9983 const CXXStdInitializerListExpr *E) {
9984 const ConstantArrayType *ArrayType =
9985 Info.Ctx.getAsConstantArrayType(E->getSubExpr()->getType());
9986
9987 LValue Array;
9988 if (!EvaluateLValue(E->getSubExpr(), Array, Info))
9989 return false;
9990
9991 // Get a pointer to the first element of the array.
9992 Array.addArray(Info, E, ArrayType);
9993
9994 auto InvalidType = [&] {
9995 Info.FFDiag(E, diag::note_constexpr_unsupported_layout)
9996 << E->getType();
9997 return false;
9998 };
9999
10000 // FIXME: Perform the checks on the field types in SemaInit.
10001 RecordDecl *Record = E->getType()->castAs<RecordType>()->getDecl();
10002 RecordDecl::field_iterator Field = Record->field_begin();
10003 if (Field == Record->field_end())
10004 return InvalidType();
10005
10006 // Start pointer.
10007 if (!Field->getType()->isPointerType() ||
10008 !Info.Ctx.hasSameType(Field->getType()->getPointeeType(),
10009 ArrayType->getElementType()))
10010 return InvalidType();
10011
10012 // FIXME: What if the initializer_list type has base classes, etc?
10013 Result = APValue(APValue::UninitStruct(), 0, 2);
10014 Array.moveInto(Result.getStructField(0));
10015
10016 if (++Field == Record->field_end())
10017 return InvalidType();
10018
10019 if (Field->getType()->isPointerType() &&
10020 Info.Ctx.hasSameType(Field->getType()->getPointeeType(),
10021 ArrayType->getElementType())) {
10022 // End pointer.
10023 if (!HandleLValueArrayAdjustment(Info, E, Array,
10024 ArrayType->getElementType(),
10025 ArrayType->getSize().getZExtValue()))
10026 return false;
10027 Array.moveInto(Result.getStructField(1));
10028 } else if (Info.Ctx.hasSameType(Field->getType(), Info.Ctx.getSizeType()))
10029 // Length.
10030 Result.getStructField(1) = APValue(APSInt(ArrayType->getSize()));
10031 else
10032 return InvalidType();
10033
10034 if (++Field != Record->field_end())
10035 return InvalidType();
10036
10037 return true;
10038 }
10039
VisitLambdaExpr(const LambdaExpr * E)10040 bool RecordExprEvaluator::VisitLambdaExpr(const LambdaExpr *E) {
10041 const CXXRecordDecl *ClosureClass = E->getLambdaClass();
10042 if (ClosureClass->isInvalidDecl())
10043 return false;
10044
10045 const size_t NumFields =
10046 std::distance(ClosureClass->field_begin(), ClosureClass->field_end());
10047
10048 assert(NumFields == (size_t)std::distance(E->capture_init_begin(),
10049 E->capture_init_end()) &&
10050 "The number of lambda capture initializers should equal the number of "
10051 "fields within the closure type");
10052
10053 Result = APValue(APValue::UninitStruct(), /*NumBases*/0, NumFields);
10054 // Iterate through all the lambda's closure object's fields and initialize
10055 // them.
10056 auto *CaptureInitIt = E->capture_init_begin();
10057 const LambdaCapture *CaptureIt = ClosureClass->captures_begin();
10058 bool Success = true;
10059 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(ClosureClass);
10060 for (const auto *Field : ClosureClass->fields()) {
10061 assert(CaptureInitIt != E->capture_init_end());
10062 // Get the initializer for this field
10063 Expr *const CurFieldInit = *CaptureInitIt++;
10064
10065 // If there is no initializer, either this is a VLA or an error has
10066 // occurred.
10067 if (!CurFieldInit)
10068 return Error(E);
10069
10070 LValue Subobject = This;
10071
10072 if (!HandleLValueMember(Info, E, Subobject, Field, &Layout))
10073 return false;
10074
10075 APValue &FieldVal = Result.getStructField(Field->getFieldIndex());
10076 if (!EvaluateInPlace(FieldVal, Info, Subobject, CurFieldInit)) {
10077 if (!Info.keepEvaluatingAfterFailure())
10078 return false;
10079 Success = false;
10080 }
10081 ++CaptureIt;
10082 }
10083 return Success;
10084 }
10085
EvaluateRecord(const Expr * E,const LValue & This,APValue & Result,EvalInfo & Info)10086 static bool EvaluateRecord(const Expr *E, const LValue &This,
10087 APValue &Result, EvalInfo &Info) {
10088 assert(!E->isValueDependent());
10089 assert(E->isPRValue() && E->getType()->isRecordType() &&
10090 "can't evaluate expression as a record rvalue");
10091 return RecordExprEvaluator(Info, This, Result).Visit(E);
10092 }
10093
10094 //===----------------------------------------------------------------------===//
10095 // Temporary Evaluation
10096 //
10097 // Temporaries are represented in the AST as rvalues, but generally behave like
10098 // lvalues. The full-object of which the temporary is a subobject is implicitly
10099 // materialized so that a reference can bind to it.
10100 //===----------------------------------------------------------------------===//
10101 namespace {
10102 class TemporaryExprEvaluator
10103 : public LValueExprEvaluatorBase<TemporaryExprEvaluator> {
10104 public:
TemporaryExprEvaluator(EvalInfo & Info,LValue & Result)10105 TemporaryExprEvaluator(EvalInfo &Info, LValue &Result) :
10106 LValueExprEvaluatorBaseTy(Info, Result, false) {}
10107
10108 /// Visit an expression which constructs the value of this temporary.
VisitConstructExpr(const Expr * E)10109 bool VisitConstructExpr(const Expr *E) {
10110 APValue &Value = Info.CurrentCall->createTemporary(
10111 E, E->getType(), ScopeKind::FullExpression, Result);
10112 return EvaluateInPlace(Value, Info, Result, E);
10113 }
10114
VisitCastExpr(const CastExpr * E)10115 bool VisitCastExpr(const CastExpr *E) {
10116 switch (E->getCastKind()) {
10117 default:
10118 return LValueExprEvaluatorBaseTy::VisitCastExpr(E);
10119
10120 case CK_ConstructorConversion:
10121 return VisitConstructExpr(E->getSubExpr());
10122 }
10123 }
VisitInitListExpr(const InitListExpr * E)10124 bool VisitInitListExpr(const InitListExpr *E) {
10125 return VisitConstructExpr(E);
10126 }
VisitCXXConstructExpr(const CXXConstructExpr * E)10127 bool VisitCXXConstructExpr(const CXXConstructExpr *E) {
10128 return VisitConstructExpr(E);
10129 }
VisitCallExpr(const CallExpr * E)10130 bool VisitCallExpr(const CallExpr *E) {
10131 return VisitConstructExpr(E);
10132 }
VisitCXXStdInitializerListExpr(const CXXStdInitializerListExpr * E)10133 bool VisitCXXStdInitializerListExpr(const CXXStdInitializerListExpr *E) {
10134 return VisitConstructExpr(E);
10135 }
VisitLambdaExpr(const LambdaExpr * E)10136 bool VisitLambdaExpr(const LambdaExpr *E) {
10137 return VisitConstructExpr(E);
10138 }
10139 };
10140 } // end anonymous namespace
10141
10142 /// Evaluate an expression of record type as a temporary.
EvaluateTemporary(const Expr * E,LValue & Result,EvalInfo & Info)10143 static bool EvaluateTemporary(const Expr *E, LValue &Result, EvalInfo &Info) {
10144 assert(!E->isValueDependent());
10145 assert(E->isPRValue() && E->getType()->isRecordType());
10146 return TemporaryExprEvaluator(Info, Result).Visit(E);
10147 }
10148
10149 //===----------------------------------------------------------------------===//
10150 // Vector Evaluation
10151 //===----------------------------------------------------------------------===//
10152
10153 namespace {
10154 class VectorExprEvaluator
10155 : public ExprEvaluatorBase<VectorExprEvaluator> {
10156 APValue &Result;
10157 public:
10158
VectorExprEvaluator(EvalInfo & info,APValue & Result)10159 VectorExprEvaluator(EvalInfo &info, APValue &Result)
10160 : ExprEvaluatorBaseTy(info), Result(Result) {}
10161
Success(ArrayRef<APValue> V,const Expr * E)10162 bool Success(ArrayRef<APValue> V, const Expr *E) {
10163 assert(V.size() == E->getType()->castAs<VectorType>()->getNumElements());
10164 // FIXME: remove this APValue copy.
10165 Result = APValue(V.data(), V.size());
10166 return true;
10167 }
Success(const APValue & V,const Expr * E)10168 bool Success(const APValue &V, const Expr *E) {
10169 assert(V.isVector());
10170 Result = V;
10171 return true;
10172 }
10173 bool ZeroInitialization(const Expr *E);
10174
VisitUnaryReal(const UnaryOperator * E)10175 bool VisitUnaryReal(const UnaryOperator *E)
10176 { return Visit(E->getSubExpr()); }
10177 bool VisitCastExpr(const CastExpr* E);
10178 bool VisitInitListExpr(const InitListExpr *E);
10179 bool VisitUnaryImag(const UnaryOperator *E);
10180 bool VisitBinaryOperator(const BinaryOperator *E);
10181 // FIXME: Missing: unary -, unary ~, conditional operator (for GNU
10182 // conditional select), shufflevector, ExtVectorElementExpr
10183 };
10184 } // end anonymous namespace
10185
EvaluateVector(const Expr * E,APValue & Result,EvalInfo & Info)10186 static bool EvaluateVector(const Expr* E, APValue& Result, EvalInfo &Info) {
10187 assert(E->isPRValue() && E->getType()->isVectorType() &&
10188 "not a vector prvalue");
10189 return VectorExprEvaluator(Info, Result).Visit(E);
10190 }
10191
VisitCastExpr(const CastExpr * E)10192 bool VectorExprEvaluator::VisitCastExpr(const CastExpr *E) {
10193 const VectorType *VTy = E->getType()->castAs<VectorType>();
10194 unsigned NElts = VTy->getNumElements();
10195
10196 const Expr *SE = E->getSubExpr();
10197 QualType SETy = SE->getType();
10198
10199 switch (E->getCastKind()) {
10200 case CK_VectorSplat: {
10201 APValue Val = APValue();
10202 if (SETy->isIntegerType()) {
10203 APSInt IntResult;
10204 if (!EvaluateInteger(SE, IntResult, Info))
10205 return false;
10206 Val = APValue(std::move(IntResult));
10207 } else if (SETy->isRealFloatingType()) {
10208 APFloat FloatResult(0.0);
10209 if (!EvaluateFloat(SE, FloatResult, Info))
10210 return false;
10211 Val = APValue(std::move(FloatResult));
10212 } else {
10213 return Error(E);
10214 }
10215
10216 // Splat and create vector APValue.
10217 SmallVector<APValue, 4> Elts(NElts, Val);
10218 return Success(Elts, E);
10219 }
10220 case CK_BitCast: {
10221 // Evaluate the operand into an APInt we can extract from.
10222 llvm::APInt SValInt;
10223 if (!EvalAndBitcastToAPInt(Info, SE, SValInt))
10224 return false;
10225 // Extract the elements
10226 QualType EltTy = VTy->getElementType();
10227 unsigned EltSize = Info.Ctx.getTypeSize(EltTy);
10228 bool BigEndian = Info.Ctx.getTargetInfo().isBigEndian();
10229 SmallVector<APValue, 4> Elts;
10230 if (EltTy->isRealFloatingType()) {
10231 const llvm::fltSemantics &Sem = Info.Ctx.getFloatTypeSemantics(EltTy);
10232 unsigned FloatEltSize = EltSize;
10233 if (&Sem == &APFloat::x87DoubleExtended())
10234 FloatEltSize = 80;
10235 for (unsigned i = 0; i < NElts; i++) {
10236 llvm::APInt Elt;
10237 if (BigEndian)
10238 Elt = SValInt.rotl(i*EltSize+FloatEltSize).trunc(FloatEltSize);
10239 else
10240 Elt = SValInt.rotr(i*EltSize).trunc(FloatEltSize);
10241 Elts.push_back(APValue(APFloat(Sem, Elt)));
10242 }
10243 } else if (EltTy->isIntegerType()) {
10244 for (unsigned i = 0; i < NElts; i++) {
10245 llvm::APInt Elt;
10246 if (BigEndian)
10247 Elt = SValInt.rotl(i*EltSize+EltSize).zextOrTrunc(EltSize);
10248 else
10249 Elt = SValInt.rotr(i*EltSize).zextOrTrunc(EltSize);
10250 Elts.push_back(APValue(APSInt(Elt, !EltTy->isSignedIntegerType())));
10251 }
10252 } else {
10253 return Error(E);
10254 }
10255 return Success(Elts, E);
10256 }
10257 default:
10258 return ExprEvaluatorBaseTy::VisitCastExpr(E);
10259 }
10260 }
10261
10262 bool
VisitInitListExpr(const InitListExpr * E)10263 VectorExprEvaluator::VisitInitListExpr(const InitListExpr *E) {
10264 const VectorType *VT = E->getType()->castAs<VectorType>();
10265 unsigned NumInits = E->getNumInits();
10266 unsigned NumElements = VT->getNumElements();
10267
10268 QualType EltTy = VT->getElementType();
10269 SmallVector<APValue, 4> Elements;
10270
10271 // The number of initializers can be less than the number of
10272 // vector elements. For OpenCL, this can be due to nested vector
10273 // initialization. For GCC compatibility, missing trailing elements
10274 // should be initialized with zeroes.
10275 unsigned CountInits = 0, CountElts = 0;
10276 while (CountElts < NumElements) {
10277 // Handle nested vector initialization.
10278 if (CountInits < NumInits
10279 && E->getInit(CountInits)->getType()->isVectorType()) {
10280 APValue v;
10281 if (!EvaluateVector(E->getInit(CountInits), v, Info))
10282 return Error(E);
10283 unsigned vlen = v.getVectorLength();
10284 for (unsigned j = 0; j < vlen; j++)
10285 Elements.push_back(v.getVectorElt(j));
10286 CountElts += vlen;
10287 } else if (EltTy->isIntegerType()) {
10288 llvm::APSInt sInt(32);
10289 if (CountInits < NumInits) {
10290 if (!EvaluateInteger(E->getInit(CountInits), sInt, Info))
10291 return false;
10292 } else // trailing integer zero.
10293 sInt = Info.Ctx.MakeIntValue(0, EltTy);
10294 Elements.push_back(APValue(sInt));
10295 CountElts++;
10296 } else {
10297 llvm::APFloat f(0.0);
10298 if (CountInits < NumInits) {
10299 if (!EvaluateFloat(E->getInit(CountInits), f, Info))
10300 return false;
10301 } else // trailing float zero.
10302 f = APFloat::getZero(Info.Ctx.getFloatTypeSemantics(EltTy));
10303 Elements.push_back(APValue(f));
10304 CountElts++;
10305 }
10306 CountInits++;
10307 }
10308 return Success(Elements, E);
10309 }
10310
10311 bool
ZeroInitialization(const Expr * E)10312 VectorExprEvaluator::ZeroInitialization(const Expr *E) {
10313 const auto *VT = E->getType()->castAs<VectorType>();
10314 QualType EltTy = VT->getElementType();
10315 APValue ZeroElement;
10316 if (EltTy->isIntegerType())
10317 ZeroElement = APValue(Info.Ctx.MakeIntValue(0, EltTy));
10318 else
10319 ZeroElement =
10320 APValue(APFloat::getZero(Info.Ctx.getFloatTypeSemantics(EltTy)));
10321
10322 SmallVector<APValue, 4> Elements(VT->getNumElements(), ZeroElement);
10323 return Success(Elements, E);
10324 }
10325
VisitUnaryImag(const UnaryOperator * E)10326 bool VectorExprEvaluator::VisitUnaryImag(const UnaryOperator *E) {
10327 VisitIgnoredValue(E->getSubExpr());
10328 return ZeroInitialization(E);
10329 }
10330
VisitBinaryOperator(const BinaryOperator * E)10331 bool VectorExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
10332 BinaryOperatorKind Op = E->getOpcode();
10333 assert(Op != BO_PtrMemD && Op != BO_PtrMemI && Op != BO_Cmp &&
10334 "Operation not supported on vector types");
10335
10336 if (Op == BO_Comma)
10337 return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
10338
10339 Expr *LHS = E->getLHS();
10340 Expr *RHS = E->getRHS();
10341
10342 assert(LHS->getType()->isVectorType() && RHS->getType()->isVectorType() &&
10343 "Must both be vector types");
10344 // Checking JUST the types are the same would be fine, except shifts don't
10345 // need to have their types be the same (since you always shift by an int).
10346 assert(LHS->getType()->castAs<VectorType>()->getNumElements() ==
10347 E->getType()->castAs<VectorType>()->getNumElements() &&
10348 RHS->getType()->castAs<VectorType>()->getNumElements() ==
10349 E->getType()->castAs<VectorType>()->getNumElements() &&
10350 "All operands must be the same size.");
10351
10352 APValue LHSValue;
10353 APValue RHSValue;
10354 bool LHSOK = Evaluate(LHSValue, Info, LHS);
10355 if (!LHSOK && !Info.noteFailure())
10356 return false;
10357 if (!Evaluate(RHSValue, Info, RHS) || !LHSOK)
10358 return false;
10359
10360 if (!handleVectorVectorBinOp(Info, E, Op, LHSValue, RHSValue))
10361 return false;
10362
10363 return Success(LHSValue, E);
10364 }
10365
10366 //===----------------------------------------------------------------------===//
10367 // Array Evaluation
10368 //===----------------------------------------------------------------------===//
10369
10370 namespace {
10371 class ArrayExprEvaluator
10372 : public ExprEvaluatorBase<ArrayExprEvaluator> {
10373 const LValue &This;
10374 APValue &Result;
10375 public:
10376
ArrayExprEvaluator(EvalInfo & Info,const LValue & This,APValue & Result)10377 ArrayExprEvaluator(EvalInfo &Info, const LValue &This, APValue &Result)
10378 : ExprEvaluatorBaseTy(Info), This(This), Result(Result) {}
10379
Success(const APValue & V,const Expr * E)10380 bool Success(const APValue &V, const Expr *E) {
10381 assert(V.isArray() && "expected array");
10382 Result = V;
10383 return true;
10384 }
10385
ZeroInitialization(const Expr * E)10386 bool ZeroInitialization(const Expr *E) {
10387 const ConstantArrayType *CAT =
10388 Info.Ctx.getAsConstantArrayType(E->getType());
10389 if (!CAT) {
10390 if (E->getType()->isIncompleteArrayType()) {
10391 // We can be asked to zero-initialize a flexible array member; this
10392 // is represented as an ImplicitValueInitExpr of incomplete array
10393 // type. In this case, the array has zero elements.
10394 Result = APValue(APValue::UninitArray(), 0, 0);
10395 return true;
10396 }
10397 // FIXME: We could handle VLAs here.
10398 return Error(E);
10399 }
10400
10401 Result = APValue(APValue::UninitArray(), 0,
10402 CAT->getSize().getZExtValue());
10403 if (!Result.hasArrayFiller())
10404 return true;
10405
10406 // Zero-initialize all elements.
10407 LValue Subobject = This;
10408 Subobject.addArray(Info, E, CAT);
10409 ImplicitValueInitExpr VIE(CAT->getElementType());
10410 return EvaluateInPlace(Result.getArrayFiller(), Info, Subobject, &VIE);
10411 }
10412
VisitCallExpr(const CallExpr * E)10413 bool VisitCallExpr(const CallExpr *E) {
10414 return handleCallExpr(E, Result, &This);
10415 }
10416 bool VisitInitListExpr(const InitListExpr *E,
10417 QualType AllocType = QualType());
10418 bool VisitArrayInitLoopExpr(const ArrayInitLoopExpr *E);
10419 bool VisitCXXConstructExpr(const CXXConstructExpr *E);
10420 bool VisitCXXConstructExpr(const CXXConstructExpr *E,
10421 const LValue &Subobject,
10422 APValue *Value, QualType Type);
VisitStringLiteral(const StringLiteral * E,QualType AllocType=QualType ())10423 bool VisitStringLiteral(const StringLiteral *E,
10424 QualType AllocType = QualType()) {
10425 expandStringLiteral(Info, E, Result, AllocType);
10426 return true;
10427 }
10428 };
10429 } // end anonymous namespace
10430
EvaluateArray(const Expr * E,const LValue & This,APValue & Result,EvalInfo & Info)10431 static bool EvaluateArray(const Expr *E, const LValue &This,
10432 APValue &Result, EvalInfo &Info) {
10433 assert(!E->isValueDependent());
10434 assert(E->isPRValue() && E->getType()->isArrayType() &&
10435 "not an array prvalue");
10436 return ArrayExprEvaluator(Info, This, Result).Visit(E);
10437 }
10438
EvaluateArrayNewInitList(EvalInfo & Info,LValue & This,APValue & Result,const InitListExpr * ILE,QualType AllocType)10439 static bool EvaluateArrayNewInitList(EvalInfo &Info, LValue &This,
10440 APValue &Result, const InitListExpr *ILE,
10441 QualType AllocType) {
10442 assert(!ILE->isValueDependent());
10443 assert(ILE->isPRValue() && ILE->getType()->isArrayType() &&
10444 "not an array prvalue");
10445 return ArrayExprEvaluator(Info, This, Result)
10446 .VisitInitListExpr(ILE, AllocType);
10447 }
10448
EvaluateArrayNewConstructExpr(EvalInfo & Info,LValue & This,APValue & Result,const CXXConstructExpr * CCE,QualType AllocType)10449 static bool EvaluateArrayNewConstructExpr(EvalInfo &Info, LValue &This,
10450 APValue &Result,
10451 const CXXConstructExpr *CCE,
10452 QualType AllocType) {
10453 assert(!CCE->isValueDependent());
10454 assert(CCE->isPRValue() && CCE->getType()->isArrayType() &&
10455 "not an array prvalue");
10456 return ArrayExprEvaluator(Info, This, Result)
10457 .VisitCXXConstructExpr(CCE, This, &Result, AllocType);
10458 }
10459
10460 // Return true iff the given array filler may depend on the element index.
MaybeElementDependentArrayFiller(const Expr * FillerExpr)10461 static bool MaybeElementDependentArrayFiller(const Expr *FillerExpr) {
10462 // For now, just allow non-class value-initialization and initialization
10463 // lists comprised of them.
10464 if (isa<ImplicitValueInitExpr>(FillerExpr))
10465 return false;
10466 if (const InitListExpr *ILE = dyn_cast<InitListExpr>(FillerExpr)) {
10467 for (unsigned I = 0, E = ILE->getNumInits(); I != E; ++I) {
10468 if (MaybeElementDependentArrayFiller(ILE->getInit(I)))
10469 return true;
10470 }
10471 return false;
10472 }
10473 return true;
10474 }
10475
VisitInitListExpr(const InitListExpr * E,QualType AllocType)10476 bool ArrayExprEvaluator::VisitInitListExpr(const InitListExpr *E,
10477 QualType AllocType) {
10478 const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(
10479 AllocType.isNull() ? E->getType() : AllocType);
10480 if (!CAT)
10481 return Error(E);
10482
10483 // C++11 [dcl.init.string]p1: A char array [...] can be initialized by [...]
10484 // an appropriately-typed string literal enclosed in braces.
10485 if (E->isStringLiteralInit()) {
10486 auto *SL = dyn_cast<StringLiteral>(E->getInit(0)->IgnoreParenImpCasts());
10487 // FIXME: Support ObjCEncodeExpr here once we support it in
10488 // ArrayExprEvaluator generally.
10489 if (!SL)
10490 return Error(E);
10491 return VisitStringLiteral(SL, AllocType);
10492 }
10493 // Any other transparent list init will need proper handling of the
10494 // AllocType; we can't just recurse to the inner initializer.
10495 assert(!E->isTransparent() &&
10496 "transparent array list initialization is not string literal init?");
10497
10498 bool Success = true;
10499
10500 assert((!Result.isArray() || Result.getArrayInitializedElts() == 0) &&
10501 "zero-initialized array shouldn't have any initialized elts");
10502 APValue Filler;
10503 if (Result.isArray() && Result.hasArrayFiller())
10504 Filler = Result.getArrayFiller();
10505
10506 unsigned NumEltsToInit = E->getNumInits();
10507 unsigned NumElts = CAT->getSize().getZExtValue();
10508 const Expr *FillerExpr = E->hasArrayFiller() ? E->getArrayFiller() : nullptr;
10509
10510 // If the initializer might depend on the array index, run it for each
10511 // array element.
10512 if (NumEltsToInit != NumElts && MaybeElementDependentArrayFiller(FillerExpr))
10513 NumEltsToInit = NumElts;
10514
10515 LLVM_DEBUG(llvm::dbgs() << "The number of elements to initialize: "
10516 << NumEltsToInit << ".\n");
10517
10518 Result = APValue(APValue::UninitArray(), NumEltsToInit, NumElts);
10519
10520 // If the array was previously zero-initialized, preserve the
10521 // zero-initialized values.
10522 if (Filler.hasValue()) {
10523 for (unsigned I = 0, E = Result.getArrayInitializedElts(); I != E; ++I)
10524 Result.getArrayInitializedElt(I) = Filler;
10525 if (Result.hasArrayFiller())
10526 Result.getArrayFiller() = Filler;
10527 }
10528
10529 LValue Subobject = This;
10530 Subobject.addArray(Info, E, CAT);
10531 for (unsigned Index = 0; Index != NumEltsToInit; ++Index) {
10532 const Expr *Init =
10533 Index < E->getNumInits() ? E->getInit(Index) : FillerExpr;
10534 if (!EvaluateInPlace(Result.getArrayInitializedElt(Index),
10535 Info, Subobject, Init) ||
10536 !HandleLValueArrayAdjustment(Info, Init, Subobject,
10537 CAT->getElementType(), 1)) {
10538 if (!Info.noteFailure())
10539 return false;
10540 Success = false;
10541 }
10542 }
10543
10544 if (!Result.hasArrayFiller())
10545 return Success;
10546
10547 // If we get here, we have a trivial filler, which we can just evaluate
10548 // once and splat over the rest of the array elements.
10549 assert(FillerExpr && "no array filler for incomplete init list");
10550 return EvaluateInPlace(Result.getArrayFiller(), Info, Subobject,
10551 FillerExpr) && Success;
10552 }
10553
VisitArrayInitLoopExpr(const ArrayInitLoopExpr * E)10554 bool ArrayExprEvaluator::VisitArrayInitLoopExpr(const ArrayInitLoopExpr *E) {
10555 LValue CommonLV;
10556 if (E->getCommonExpr() &&
10557 !Evaluate(Info.CurrentCall->createTemporary(
10558 E->getCommonExpr(),
10559 getStorageType(Info.Ctx, E->getCommonExpr()),
10560 ScopeKind::FullExpression, CommonLV),
10561 Info, E->getCommonExpr()->getSourceExpr()))
10562 return false;
10563
10564 auto *CAT = cast<ConstantArrayType>(E->getType()->castAsArrayTypeUnsafe());
10565
10566 uint64_t Elements = CAT->getSize().getZExtValue();
10567 Result = APValue(APValue::UninitArray(), Elements, Elements);
10568
10569 LValue Subobject = This;
10570 Subobject.addArray(Info, E, CAT);
10571
10572 bool Success = true;
10573 for (EvalInfo::ArrayInitLoopIndex Index(Info); Index != Elements; ++Index) {
10574 if (!EvaluateInPlace(Result.getArrayInitializedElt(Index),
10575 Info, Subobject, E->getSubExpr()) ||
10576 !HandleLValueArrayAdjustment(Info, E, Subobject,
10577 CAT->getElementType(), 1)) {
10578 if (!Info.noteFailure())
10579 return false;
10580 Success = false;
10581 }
10582 }
10583
10584 return Success;
10585 }
10586
VisitCXXConstructExpr(const CXXConstructExpr * E)10587 bool ArrayExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E) {
10588 return VisitCXXConstructExpr(E, This, &Result, E->getType());
10589 }
10590
VisitCXXConstructExpr(const CXXConstructExpr * E,const LValue & Subobject,APValue * Value,QualType Type)10591 bool ArrayExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E,
10592 const LValue &Subobject,
10593 APValue *Value,
10594 QualType Type) {
10595 bool HadZeroInit = Value->hasValue();
10596
10597 if (const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(Type)) {
10598 unsigned N = CAT->getSize().getZExtValue();
10599
10600 // Preserve the array filler if we had prior zero-initialization.
10601 APValue Filler =
10602 HadZeroInit && Value->hasArrayFiller() ? Value->getArrayFiller()
10603 : APValue();
10604
10605 *Value = APValue(APValue::UninitArray(), N, N);
10606
10607 if (HadZeroInit)
10608 for (unsigned I = 0; I != N; ++I)
10609 Value->getArrayInitializedElt(I) = Filler;
10610
10611 // Initialize the elements.
10612 LValue ArrayElt = Subobject;
10613 ArrayElt.addArray(Info, E, CAT);
10614 for (unsigned I = 0; I != N; ++I)
10615 if (!VisitCXXConstructExpr(E, ArrayElt, &Value->getArrayInitializedElt(I),
10616 CAT->getElementType()) ||
10617 !HandleLValueArrayAdjustment(Info, E, ArrayElt,
10618 CAT->getElementType(), 1))
10619 return false;
10620
10621 return true;
10622 }
10623
10624 if (!Type->isRecordType())
10625 return Error(E);
10626
10627 return RecordExprEvaluator(Info, Subobject, *Value)
10628 .VisitCXXConstructExpr(E, Type);
10629 }
10630
10631 //===----------------------------------------------------------------------===//
10632 // Integer Evaluation
10633 //
10634 // As a GNU extension, we support casting pointers to sufficiently-wide integer
10635 // types and back in constant folding. Integer values are thus represented
10636 // either as an integer-valued APValue, or as an lvalue-valued APValue.
10637 //===----------------------------------------------------------------------===//
10638
10639 namespace {
10640 class IntExprEvaluator
10641 : public ExprEvaluatorBase<IntExprEvaluator> {
10642 APValue &Result;
10643 public:
IntExprEvaluator(EvalInfo & info,APValue & result)10644 IntExprEvaluator(EvalInfo &info, APValue &result)
10645 : ExprEvaluatorBaseTy(info), Result(result) {}
10646
Success(const llvm::APSInt & SI,const Expr * E,APValue & Result)10647 bool Success(const llvm::APSInt &SI, const Expr *E, APValue &Result) {
10648 assert(E->getType()->isIntegralOrEnumerationType() &&
10649 "Invalid evaluation result.");
10650 assert(SI.isSigned() == E->getType()->isSignedIntegerOrEnumerationType() &&
10651 "Invalid evaluation result.");
10652 assert(SI.getBitWidth() == Info.Ctx.getIntWidth(E->getType()) &&
10653 "Invalid evaluation result.");
10654 Result = APValue(SI);
10655 return true;
10656 }
Success(const llvm::APSInt & SI,const Expr * E)10657 bool Success(const llvm::APSInt &SI, const Expr *E) {
10658 return Success(SI, E, Result);
10659 }
10660
Success(const llvm::APInt & I,const Expr * E,APValue & Result)10661 bool Success(const llvm::APInt &I, const Expr *E, APValue &Result) {
10662 assert(E->getType()->isIntegralOrEnumerationType() &&
10663 "Invalid evaluation result.");
10664 assert(I.getBitWidth() == Info.Ctx.getIntWidth(E->getType()) &&
10665 "Invalid evaluation result.");
10666 Result = APValue(APSInt(I));
10667 Result.getInt().setIsUnsigned(
10668 E->getType()->isUnsignedIntegerOrEnumerationType());
10669 return true;
10670 }
Success(const llvm::APInt & I,const Expr * E)10671 bool Success(const llvm::APInt &I, const Expr *E) {
10672 return Success(I, E, Result);
10673 }
10674
Success(uint64_t Value,const Expr * E,APValue & Result)10675 bool Success(uint64_t Value, const Expr *E, APValue &Result) {
10676 assert(E->getType()->isIntegralOrEnumerationType() &&
10677 "Invalid evaluation result.");
10678 Result = APValue(Info.Ctx.MakeIntValue(Value, E->getType()));
10679 return true;
10680 }
Success(uint64_t Value,const Expr * E)10681 bool Success(uint64_t Value, const Expr *E) {
10682 return Success(Value, E, Result);
10683 }
10684
Success(CharUnits Size,const Expr * E)10685 bool Success(CharUnits Size, const Expr *E) {
10686 return Success(Size.getQuantity(), E);
10687 }
10688
Success(const APValue & V,const Expr * E)10689 bool Success(const APValue &V, const Expr *E) {
10690 if (V.isLValue() || V.isAddrLabelDiff() || V.isIndeterminate()) {
10691 Result = V;
10692 return true;
10693 }
10694 return Success(V.getInt(), E);
10695 }
10696
ZeroInitialization(const Expr * E)10697 bool ZeroInitialization(const Expr *E) { return Success(0, E); }
10698
10699 //===--------------------------------------------------------------------===//
10700 // Visitor Methods
10701 //===--------------------------------------------------------------------===//
10702
VisitIntegerLiteral(const IntegerLiteral * E)10703 bool VisitIntegerLiteral(const IntegerLiteral *E) {
10704 return Success(E->getValue(), E);
10705 }
VisitCharacterLiteral(const CharacterLiteral * E)10706 bool VisitCharacterLiteral(const CharacterLiteral *E) {
10707 return Success(E->getValue(), E);
10708 }
10709
10710 bool CheckReferencedDecl(const Expr *E, const Decl *D);
VisitDeclRefExpr(const DeclRefExpr * E)10711 bool VisitDeclRefExpr(const DeclRefExpr *E) {
10712 if (CheckReferencedDecl(E, E->getDecl()))
10713 return true;
10714
10715 return ExprEvaluatorBaseTy::VisitDeclRefExpr(E);
10716 }
VisitMemberExpr(const MemberExpr * E)10717 bool VisitMemberExpr(const MemberExpr *E) {
10718 if (CheckReferencedDecl(E, E->getMemberDecl())) {
10719 VisitIgnoredBaseExpression(E->getBase());
10720 return true;
10721 }
10722
10723 return ExprEvaluatorBaseTy::VisitMemberExpr(E);
10724 }
10725
10726 bool VisitCallExpr(const CallExpr *E);
10727 bool VisitBuiltinCallExpr(const CallExpr *E, unsigned BuiltinOp);
10728 bool VisitBinaryOperator(const BinaryOperator *E);
10729 bool VisitOffsetOfExpr(const OffsetOfExpr *E);
10730 bool VisitUnaryOperator(const UnaryOperator *E);
10731
10732 bool VisitCastExpr(const CastExpr* E);
10733 bool VisitUnaryExprOrTypeTraitExpr(const UnaryExprOrTypeTraitExpr *E);
10734
VisitCXXBoolLiteralExpr(const CXXBoolLiteralExpr * E)10735 bool VisitCXXBoolLiteralExpr(const CXXBoolLiteralExpr *E) {
10736 return Success(E->getValue(), E);
10737 }
10738
VisitObjCBoolLiteralExpr(const ObjCBoolLiteralExpr * E)10739 bool VisitObjCBoolLiteralExpr(const ObjCBoolLiteralExpr *E) {
10740 return Success(E->getValue(), E);
10741 }
10742
VisitArrayInitIndexExpr(const ArrayInitIndexExpr * E)10743 bool VisitArrayInitIndexExpr(const ArrayInitIndexExpr *E) {
10744 if (Info.ArrayInitIndex == uint64_t(-1)) {
10745 // We were asked to evaluate this subexpression independent of the
10746 // enclosing ArrayInitLoopExpr. We can't do that.
10747 Info.FFDiag(E);
10748 return false;
10749 }
10750 return Success(Info.ArrayInitIndex, E);
10751 }
10752
10753 // Note, GNU defines __null as an integer, not a pointer.
VisitGNUNullExpr(const GNUNullExpr * E)10754 bool VisitGNUNullExpr(const GNUNullExpr *E) {
10755 return ZeroInitialization(E);
10756 }
10757
VisitTypeTraitExpr(const TypeTraitExpr * E)10758 bool VisitTypeTraitExpr(const TypeTraitExpr *E) {
10759 return Success(E->getValue(), E);
10760 }
10761
VisitArrayTypeTraitExpr(const ArrayTypeTraitExpr * E)10762 bool VisitArrayTypeTraitExpr(const ArrayTypeTraitExpr *E) {
10763 return Success(E->getValue(), E);
10764 }
10765
VisitExpressionTraitExpr(const ExpressionTraitExpr * E)10766 bool VisitExpressionTraitExpr(const ExpressionTraitExpr *E) {
10767 return Success(E->getValue(), E);
10768 }
10769
10770 bool VisitUnaryReal(const UnaryOperator *E);
10771 bool VisitUnaryImag(const UnaryOperator *E);
10772
10773 bool VisitCXXNoexceptExpr(const CXXNoexceptExpr *E);
10774 bool VisitSizeOfPackExpr(const SizeOfPackExpr *E);
10775 bool VisitSourceLocExpr(const SourceLocExpr *E);
10776 bool VisitConceptSpecializationExpr(const ConceptSpecializationExpr *E);
10777 bool VisitRequiresExpr(const RequiresExpr *E);
10778 // FIXME: Missing: array subscript of vector, member of vector
10779 };
10780
10781 class FixedPointExprEvaluator
10782 : public ExprEvaluatorBase<FixedPointExprEvaluator> {
10783 APValue &Result;
10784
10785 public:
FixedPointExprEvaluator(EvalInfo & info,APValue & result)10786 FixedPointExprEvaluator(EvalInfo &info, APValue &result)
10787 : ExprEvaluatorBaseTy(info), Result(result) {}
10788
Success(const llvm::APInt & I,const Expr * E)10789 bool Success(const llvm::APInt &I, const Expr *E) {
10790 return Success(
10791 APFixedPoint(I, Info.Ctx.getFixedPointSemantics(E->getType())), E);
10792 }
10793
Success(uint64_t Value,const Expr * E)10794 bool Success(uint64_t Value, const Expr *E) {
10795 return Success(
10796 APFixedPoint(Value, Info.Ctx.getFixedPointSemantics(E->getType())), E);
10797 }
10798
Success(const APValue & V,const Expr * E)10799 bool Success(const APValue &V, const Expr *E) {
10800 return Success(V.getFixedPoint(), E);
10801 }
10802
Success(const APFixedPoint & V,const Expr * E)10803 bool Success(const APFixedPoint &V, const Expr *E) {
10804 assert(E->getType()->isFixedPointType() && "Invalid evaluation result.");
10805 assert(V.getWidth() == Info.Ctx.getIntWidth(E->getType()) &&
10806 "Invalid evaluation result.");
10807 Result = APValue(V);
10808 return true;
10809 }
10810
10811 //===--------------------------------------------------------------------===//
10812 // Visitor Methods
10813 //===--------------------------------------------------------------------===//
10814
VisitFixedPointLiteral(const FixedPointLiteral * E)10815 bool VisitFixedPointLiteral(const FixedPointLiteral *E) {
10816 return Success(E->getValue(), E);
10817 }
10818
10819 bool VisitCastExpr(const CastExpr *E);
10820 bool VisitUnaryOperator(const UnaryOperator *E);
10821 bool VisitBinaryOperator(const BinaryOperator *E);
10822 };
10823 } // end anonymous namespace
10824
10825 /// EvaluateIntegerOrLValue - Evaluate an rvalue integral-typed expression, and
10826 /// produce either the integer value or a pointer.
10827 ///
10828 /// GCC has a heinous extension which folds casts between pointer types and
10829 /// pointer-sized integral types. We support this by allowing the evaluation of
10830 /// an integer rvalue to produce a pointer (represented as an lvalue) instead.
10831 /// Some simple arithmetic on such values is supported (they are treated much
10832 /// like char*).
EvaluateIntegerOrLValue(const Expr * E,APValue & Result,EvalInfo & Info)10833 static bool EvaluateIntegerOrLValue(const Expr *E, APValue &Result,
10834 EvalInfo &Info) {
10835 assert(!E->isValueDependent());
10836 assert(E->isPRValue() && E->getType()->isIntegralOrEnumerationType());
10837 return IntExprEvaluator(Info, Result).Visit(E);
10838 }
10839
EvaluateInteger(const Expr * E,APSInt & Result,EvalInfo & Info)10840 static bool EvaluateInteger(const Expr *E, APSInt &Result, EvalInfo &Info) {
10841 assert(!E->isValueDependent());
10842 APValue Val;
10843 if (!EvaluateIntegerOrLValue(E, Val, Info))
10844 return false;
10845 if (!Val.isInt()) {
10846 // FIXME: It would be better to produce the diagnostic for casting
10847 // a pointer to an integer.
10848 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
10849 return false;
10850 }
10851 Result = Val.getInt();
10852 return true;
10853 }
10854
VisitSourceLocExpr(const SourceLocExpr * E)10855 bool IntExprEvaluator::VisitSourceLocExpr(const SourceLocExpr *E) {
10856 APValue Evaluated = E->EvaluateInContext(
10857 Info.Ctx, Info.CurrentCall->CurSourceLocExprScope.getDefaultExpr());
10858 return Success(Evaluated, E);
10859 }
10860
EvaluateFixedPoint(const Expr * E,APFixedPoint & Result,EvalInfo & Info)10861 static bool EvaluateFixedPoint(const Expr *E, APFixedPoint &Result,
10862 EvalInfo &Info) {
10863 assert(!E->isValueDependent());
10864 if (E->getType()->isFixedPointType()) {
10865 APValue Val;
10866 if (!FixedPointExprEvaluator(Info, Val).Visit(E))
10867 return false;
10868 if (!Val.isFixedPoint())
10869 return false;
10870
10871 Result = Val.getFixedPoint();
10872 return true;
10873 }
10874 return false;
10875 }
10876
EvaluateFixedPointOrInteger(const Expr * E,APFixedPoint & Result,EvalInfo & Info)10877 static bool EvaluateFixedPointOrInteger(const Expr *E, APFixedPoint &Result,
10878 EvalInfo &Info) {
10879 assert(!E->isValueDependent());
10880 if (E->getType()->isIntegerType()) {
10881 auto FXSema = Info.Ctx.getFixedPointSemantics(E->getType());
10882 APSInt Val;
10883 if (!EvaluateInteger(E, Val, Info))
10884 return false;
10885 Result = APFixedPoint(Val, FXSema);
10886 return true;
10887 } else if (E->getType()->isFixedPointType()) {
10888 return EvaluateFixedPoint(E, Result, Info);
10889 }
10890 return false;
10891 }
10892
10893 /// Check whether the given declaration can be directly converted to an integral
10894 /// rvalue. If not, no diagnostic is produced; there are other things we can
10895 /// try.
CheckReferencedDecl(const Expr * E,const Decl * D)10896 bool IntExprEvaluator::CheckReferencedDecl(const Expr* E, const Decl* D) {
10897 // Enums are integer constant exprs.
10898 if (const EnumConstantDecl *ECD = dyn_cast<EnumConstantDecl>(D)) {
10899 // Check for signedness/width mismatches between E type and ECD value.
10900 bool SameSign = (ECD->getInitVal().isSigned()
10901 == E->getType()->isSignedIntegerOrEnumerationType());
10902 bool SameWidth = (ECD->getInitVal().getBitWidth()
10903 == Info.Ctx.getIntWidth(E->getType()));
10904 if (SameSign && SameWidth)
10905 return Success(ECD->getInitVal(), E);
10906 else {
10907 // Get rid of mismatch (otherwise Success assertions will fail)
10908 // by computing a new value matching the type of E.
10909 llvm::APSInt Val = ECD->getInitVal();
10910 if (!SameSign)
10911 Val.setIsSigned(!ECD->getInitVal().isSigned());
10912 if (!SameWidth)
10913 Val = Val.extOrTrunc(Info.Ctx.getIntWidth(E->getType()));
10914 return Success(Val, E);
10915 }
10916 }
10917 return false;
10918 }
10919
10920 /// Values returned by __builtin_classify_type, chosen to match the values
10921 /// produced by GCC's builtin.
10922 enum class GCCTypeClass {
10923 None = -1,
10924 Void = 0,
10925 Integer = 1,
10926 // GCC reserves 2 for character types, but instead classifies them as
10927 // integers.
10928 Enum = 3,
10929 Bool = 4,
10930 Pointer = 5,
10931 // GCC reserves 6 for references, but appears to never use it (because
10932 // expressions never have reference type, presumably).
10933 PointerToDataMember = 7,
10934 RealFloat = 8,
10935 Complex = 9,
10936 // GCC reserves 10 for functions, but does not use it since GCC version 6 due
10937 // to decay to pointer. (Prior to version 6 it was only used in C++ mode).
10938 // GCC claims to reserve 11 for pointers to member functions, but *actually*
10939 // uses 12 for that purpose, same as for a class or struct. Maybe it
10940 // internally implements a pointer to member as a struct? Who knows.
10941 PointerToMemberFunction = 12, // Not a bug, see above.
10942 ClassOrStruct = 12,
10943 Union = 13,
10944 // GCC reserves 14 for arrays, but does not use it since GCC version 6 due to
10945 // decay to pointer. (Prior to version 6 it was only used in C++ mode).
10946 // GCC reserves 15 for strings, but actually uses 5 (pointer) for string
10947 // literals.
10948 };
10949
10950 /// EvaluateBuiltinClassifyType - Evaluate __builtin_classify_type the same way
10951 /// as GCC.
10952 static GCCTypeClass
EvaluateBuiltinClassifyType(QualType T,const LangOptions & LangOpts)10953 EvaluateBuiltinClassifyType(QualType T, const LangOptions &LangOpts) {
10954 assert(!T->isDependentType() && "unexpected dependent type");
10955
10956 QualType CanTy = T.getCanonicalType();
10957 const BuiltinType *BT = dyn_cast<BuiltinType>(CanTy);
10958
10959 switch (CanTy->getTypeClass()) {
10960 #define TYPE(ID, BASE)
10961 #define DEPENDENT_TYPE(ID, BASE) case Type::ID:
10962 #define NON_CANONICAL_TYPE(ID, BASE) case Type::ID:
10963 #define NON_CANONICAL_UNLESS_DEPENDENT_TYPE(ID, BASE) case Type::ID:
10964 #include "clang/AST/TypeNodes.inc"
10965 case Type::Auto:
10966 case Type::DeducedTemplateSpecialization:
10967 llvm_unreachable("unexpected non-canonical or dependent type");
10968
10969 case Type::Builtin:
10970 switch (BT->getKind()) {
10971 #define BUILTIN_TYPE(ID, SINGLETON_ID)
10972 #define SIGNED_TYPE(ID, SINGLETON_ID) \
10973 case BuiltinType::ID: return GCCTypeClass::Integer;
10974 #define FLOATING_TYPE(ID, SINGLETON_ID) \
10975 case BuiltinType::ID: return GCCTypeClass::RealFloat;
10976 #define PLACEHOLDER_TYPE(ID, SINGLETON_ID) \
10977 case BuiltinType::ID: break;
10978 #include "clang/AST/BuiltinTypes.def"
10979 case BuiltinType::Void:
10980 return GCCTypeClass::Void;
10981
10982 case BuiltinType::Bool:
10983 return GCCTypeClass::Bool;
10984
10985 case BuiltinType::Char_U:
10986 case BuiltinType::UChar:
10987 case BuiltinType::WChar_U:
10988 case BuiltinType::Char8:
10989 case BuiltinType::Char16:
10990 case BuiltinType::Char32:
10991 case BuiltinType::UShort:
10992 case BuiltinType::UInt:
10993 case BuiltinType::ULong:
10994 case BuiltinType::ULongLong:
10995 case BuiltinType::UInt128:
10996 return GCCTypeClass::Integer;
10997
10998 case BuiltinType::UShortAccum:
10999 case BuiltinType::UAccum:
11000 case BuiltinType::ULongAccum:
11001 case BuiltinType::UShortFract:
11002 case BuiltinType::UFract:
11003 case BuiltinType::ULongFract:
11004 case BuiltinType::SatUShortAccum:
11005 case BuiltinType::SatUAccum:
11006 case BuiltinType::SatULongAccum:
11007 case BuiltinType::SatUShortFract:
11008 case BuiltinType::SatUFract:
11009 case BuiltinType::SatULongFract:
11010 return GCCTypeClass::None;
11011
11012 case BuiltinType::NullPtr:
11013
11014 case BuiltinType::ObjCId:
11015 case BuiltinType::ObjCClass:
11016 case BuiltinType::ObjCSel:
11017 #define IMAGE_TYPE(ImgType, Id, SingletonId, Access, Suffix) \
11018 case BuiltinType::Id:
11019 #include "clang/Basic/OpenCLImageTypes.def"
11020 #define EXT_OPAQUE_TYPE(ExtType, Id, Ext) \
11021 case BuiltinType::Id:
11022 #include "clang/Basic/OpenCLExtensionTypes.def"
11023 case BuiltinType::OCLSampler:
11024 case BuiltinType::OCLEvent:
11025 case BuiltinType::OCLClkEvent:
11026 case BuiltinType::OCLQueue:
11027 case BuiltinType::OCLReserveID:
11028 #define SVE_TYPE(Name, Id, SingletonId) \
11029 case BuiltinType::Id:
11030 #include "clang/Basic/AArch64SVEACLETypes.def"
11031 #define PPC_VECTOR_TYPE(Name, Id, Size) \
11032 case BuiltinType::Id:
11033 #include "clang/Basic/PPCTypes.def"
11034 #define RVV_TYPE(Name, Id, SingletonId) case BuiltinType::Id:
11035 #include "clang/Basic/RISCVVTypes.def"
11036 return GCCTypeClass::None;
11037
11038 case BuiltinType::Dependent:
11039 llvm_unreachable("unexpected dependent type");
11040 };
11041 llvm_unreachable("unexpected placeholder type");
11042
11043 case Type::Enum:
11044 return LangOpts.CPlusPlus ? GCCTypeClass::Enum : GCCTypeClass::Integer;
11045
11046 case Type::Pointer:
11047 case Type::ConstantArray:
11048 case Type::VariableArray:
11049 case Type::IncompleteArray:
11050 case Type::FunctionNoProto:
11051 case Type::FunctionProto:
11052 return GCCTypeClass::Pointer;
11053
11054 case Type::MemberPointer:
11055 return CanTy->isMemberDataPointerType()
11056 ? GCCTypeClass::PointerToDataMember
11057 : GCCTypeClass::PointerToMemberFunction;
11058
11059 case Type::Complex:
11060 return GCCTypeClass::Complex;
11061
11062 case Type::Record:
11063 return CanTy->isUnionType() ? GCCTypeClass::Union
11064 : GCCTypeClass::ClassOrStruct;
11065
11066 case Type::Atomic:
11067 // GCC classifies _Atomic T the same as T.
11068 return EvaluateBuiltinClassifyType(
11069 CanTy->castAs<AtomicType>()->getValueType(), LangOpts);
11070
11071 case Type::BlockPointer:
11072 case Type::Vector:
11073 case Type::ExtVector:
11074 case Type::ConstantMatrix:
11075 case Type::ObjCObject:
11076 case Type::ObjCInterface:
11077 case Type::ObjCObjectPointer:
11078 case Type::Pipe:
11079 case Type::ExtInt:
11080 // GCC classifies vectors as None. We follow its lead and classify all
11081 // other types that don't fit into the regular classification the same way.
11082 return GCCTypeClass::None;
11083
11084 case Type::LValueReference:
11085 case Type::RValueReference:
11086 llvm_unreachable("invalid type for expression");
11087 }
11088
11089 llvm_unreachable("unexpected type class");
11090 }
11091
11092 /// EvaluateBuiltinClassifyType - Evaluate __builtin_classify_type the same way
11093 /// as GCC.
11094 static GCCTypeClass
EvaluateBuiltinClassifyType(const CallExpr * E,const LangOptions & LangOpts)11095 EvaluateBuiltinClassifyType(const CallExpr *E, const LangOptions &LangOpts) {
11096 // If no argument was supplied, default to None. This isn't
11097 // ideal, however it is what gcc does.
11098 if (E->getNumArgs() == 0)
11099 return GCCTypeClass::None;
11100
11101 // FIXME: Bizarrely, GCC treats a call with more than one argument as not
11102 // being an ICE, but still folds it to a constant using the type of the first
11103 // argument.
11104 return EvaluateBuiltinClassifyType(E->getArg(0)->getType(), LangOpts);
11105 }
11106
11107 /// EvaluateBuiltinConstantPForLValue - Determine the result of
11108 /// __builtin_constant_p when applied to the given pointer.
11109 ///
11110 /// A pointer is only "constant" if it is null (or a pointer cast to integer)
11111 /// or it points to the first character of a string literal.
EvaluateBuiltinConstantPForLValue(const APValue & LV)11112 static bool EvaluateBuiltinConstantPForLValue(const APValue &LV) {
11113 APValue::LValueBase Base = LV.getLValueBase();
11114 if (Base.isNull()) {
11115 // A null base is acceptable.
11116 return true;
11117 } else if (const Expr *E = Base.dyn_cast<const Expr *>()) {
11118 if (!isa<StringLiteral>(E))
11119 return false;
11120 return LV.getLValueOffset().isZero();
11121 } else if (Base.is<TypeInfoLValue>()) {
11122 // Surprisingly, GCC considers __builtin_constant_p(&typeid(int)) to
11123 // evaluate to true.
11124 return true;
11125 } else {
11126 // Any other base is not constant enough for GCC.
11127 return false;
11128 }
11129 }
11130
11131 /// EvaluateBuiltinConstantP - Evaluate __builtin_constant_p as similarly to
11132 /// GCC as we can manage.
EvaluateBuiltinConstantP(EvalInfo & Info,const Expr * Arg)11133 static bool EvaluateBuiltinConstantP(EvalInfo &Info, const Expr *Arg) {
11134 // This evaluation is not permitted to have side-effects, so evaluate it in
11135 // a speculative evaluation context.
11136 SpeculativeEvaluationRAII SpeculativeEval(Info);
11137
11138 // Constant-folding is always enabled for the operand of __builtin_constant_p
11139 // (even when the enclosing evaluation context otherwise requires a strict
11140 // language-specific constant expression).
11141 FoldConstant Fold(Info, true);
11142
11143 QualType ArgType = Arg->getType();
11144
11145 // __builtin_constant_p always has one operand. The rules which gcc follows
11146 // are not precisely documented, but are as follows:
11147 //
11148 // - If the operand is of integral, floating, complex or enumeration type,
11149 // and can be folded to a known value of that type, it returns 1.
11150 // - If the operand can be folded to a pointer to the first character
11151 // of a string literal (or such a pointer cast to an integral type)
11152 // or to a null pointer or an integer cast to a pointer, it returns 1.
11153 //
11154 // Otherwise, it returns 0.
11155 //
11156 // FIXME: GCC also intends to return 1 for literals of aggregate types, but
11157 // its support for this did not work prior to GCC 9 and is not yet well
11158 // understood.
11159 if (ArgType->isIntegralOrEnumerationType() || ArgType->isFloatingType() ||
11160 ArgType->isAnyComplexType() || ArgType->isPointerType() ||
11161 ArgType->isNullPtrType()) {
11162 APValue V;
11163 if (!::EvaluateAsRValue(Info, Arg, V) || Info.EvalStatus.HasSideEffects) {
11164 Fold.keepDiagnostics();
11165 return false;
11166 }
11167
11168 // For a pointer (possibly cast to integer), there are special rules.
11169 if (V.getKind() == APValue::LValue)
11170 return EvaluateBuiltinConstantPForLValue(V);
11171
11172 // Otherwise, any constant value is good enough.
11173 return V.hasValue();
11174 }
11175
11176 // Anything else isn't considered to be sufficiently constant.
11177 return false;
11178 }
11179
11180 /// Retrieves the "underlying object type" of the given expression,
11181 /// as used by __builtin_object_size.
getObjectType(APValue::LValueBase B)11182 static QualType getObjectType(APValue::LValueBase B) {
11183 if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) {
11184 if (const VarDecl *VD = dyn_cast<VarDecl>(D))
11185 return VD->getType();
11186 } else if (const Expr *E = B.dyn_cast<const Expr*>()) {
11187 if (isa<CompoundLiteralExpr>(E))
11188 return E->getType();
11189 } else if (B.is<TypeInfoLValue>()) {
11190 return B.getTypeInfoType();
11191 } else if (B.is<DynamicAllocLValue>()) {
11192 return B.getDynamicAllocType();
11193 }
11194
11195 return QualType();
11196 }
11197
11198 /// A more selective version of E->IgnoreParenCasts for
11199 /// tryEvaluateBuiltinObjectSize. This ignores some casts/parens that serve only
11200 /// to change the type of E.
11201 /// Ex. For E = `(short*)((char*)(&foo))`, returns `&foo`
11202 ///
11203 /// Always returns an RValue with a pointer representation.
ignorePointerCastsAndParens(const Expr * E)11204 static const Expr *ignorePointerCastsAndParens(const Expr *E) {
11205 assert(E->isPRValue() && E->getType()->hasPointerRepresentation());
11206
11207 auto *NoParens = E->IgnoreParens();
11208 auto *Cast = dyn_cast<CastExpr>(NoParens);
11209 if (Cast == nullptr)
11210 return NoParens;
11211
11212 // We only conservatively allow a few kinds of casts, because this code is
11213 // inherently a simple solution that seeks to support the common case.
11214 auto CastKind = Cast->getCastKind();
11215 if (CastKind != CK_NoOp && CastKind != CK_BitCast &&
11216 CastKind != CK_AddressSpaceConversion)
11217 return NoParens;
11218
11219 auto *SubExpr = Cast->getSubExpr();
11220 if (!SubExpr->getType()->hasPointerRepresentation() || !SubExpr->isPRValue())
11221 return NoParens;
11222 return ignorePointerCastsAndParens(SubExpr);
11223 }
11224
11225 /// Checks to see if the given LValue's Designator is at the end of the LValue's
11226 /// record layout. e.g.
11227 /// struct { struct { int a, b; } fst, snd; } obj;
11228 /// obj.fst // no
11229 /// obj.snd // yes
11230 /// obj.fst.a // no
11231 /// obj.fst.b // no
11232 /// obj.snd.a // no
11233 /// obj.snd.b // yes
11234 ///
11235 /// Please note: this function is specialized for how __builtin_object_size
11236 /// views "objects".
11237 ///
11238 /// If this encounters an invalid RecordDecl or otherwise cannot determine the
11239 /// correct result, it will always return true.
isDesignatorAtObjectEnd(const ASTContext & Ctx,const LValue & LVal)11240 static bool isDesignatorAtObjectEnd(const ASTContext &Ctx, const LValue &LVal) {
11241 assert(!LVal.Designator.Invalid);
11242
11243 auto IsLastOrInvalidFieldDecl = [&Ctx](const FieldDecl *FD, bool &Invalid) {
11244 const RecordDecl *Parent = FD->getParent();
11245 Invalid = Parent->isInvalidDecl();
11246 if (Invalid || Parent->isUnion())
11247 return true;
11248 const ASTRecordLayout &Layout = Ctx.getASTRecordLayout(Parent);
11249 return FD->getFieldIndex() + 1 == Layout.getFieldCount();
11250 };
11251
11252 auto &Base = LVal.getLValueBase();
11253 if (auto *ME = dyn_cast_or_null<MemberExpr>(Base.dyn_cast<const Expr *>())) {
11254 if (auto *FD = dyn_cast<FieldDecl>(ME->getMemberDecl())) {
11255 bool Invalid;
11256 if (!IsLastOrInvalidFieldDecl(FD, Invalid))
11257 return Invalid;
11258 } else if (auto *IFD = dyn_cast<IndirectFieldDecl>(ME->getMemberDecl())) {
11259 for (auto *FD : IFD->chain()) {
11260 bool Invalid;
11261 if (!IsLastOrInvalidFieldDecl(cast<FieldDecl>(FD), Invalid))
11262 return Invalid;
11263 }
11264 }
11265 }
11266
11267 unsigned I = 0;
11268 QualType BaseType = getType(Base);
11269 if (LVal.Designator.FirstEntryIsAnUnsizedArray) {
11270 // If we don't know the array bound, conservatively assume we're looking at
11271 // the final array element.
11272 ++I;
11273 if (BaseType->isIncompleteArrayType())
11274 BaseType = Ctx.getAsArrayType(BaseType)->getElementType();
11275 else
11276 BaseType = BaseType->castAs<PointerType>()->getPointeeType();
11277 }
11278
11279 for (unsigned E = LVal.Designator.Entries.size(); I != E; ++I) {
11280 const auto &Entry = LVal.Designator.Entries[I];
11281 if (BaseType->isArrayType()) {
11282 // Because __builtin_object_size treats arrays as objects, we can ignore
11283 // the index iff this is the last array in the Designator.
11284 if (I + 1 == E)
11285 return true;
11286 const auto *CAT = cast<ConstantArrayType>(Ctx.getAsArrayType(BaseType));
11287 uint64_t Index = Entry.getAsArrayIndex();
11288 if (Index + 1 != CAT->getSize())
11289 return false;
11290 BaseType = CAT->getElementType();
11291 } else if (BaseType->isAnyComplexType()) {
11292 const auto *CT = BaseType->castAs<ComplexType>();
11293 uint64_t Index = Entry.getAsArrayIndex();
11294 if (Index != 1)
11295 return false;
11296 BaseType = CT->getElementType();
11297 } else if (auto *FD = getAsField(Entry)) {
11298 bool Invalid;
11299 if (!IsLastOrInvalidFieldDecl(FD, Invalid))
11300 return Invalid;
11301 BaseType = FD->getType();
11302 } else {
11303 assert(getAsBaseClass(Entry) && "Expecting cast to a base class");
11304 return false;
11305 }
11306 }
11307 return true;
11308 }
11309
11310 /// Tests to see if the LValue has a user-specified designator (that isn't
11311 /// necessarily valid). Note that this always returns 'true' if the LValue has
11312 /// an unsized array as its first designator entry, because there's currently no
11313 /// way to tell if the user typed *foo or foo[0].
refersToCompleteObject(const LValue & LVal)11314 static bool refersToCompleteObject(const LValue &LVal) {
11315 if (LVal.Designator.Invalid)
11316 return false;
11317
11318 if (!LVal.Designator.Entries.empty())
11319 return LVal.Designator.isMostDerivedAnUnsizedArray();
11320
11321 if (!LVal.InvalidBase)
11322 return true;
11323
11324 // If `E` is a MemberExpr, then the first part of the designator is hiding in
11325 // the LValueBase.
11326 const auto *E = LVal.Base.dyn_cast<const Expr *>();
11327 return !E || !isa<MemberExpr>(E);
11328 }
11329
11330 /// Attempts to detect a user writing into a piece of memory that's impossible
11331 /// to figure out the size of by just using types.
isUserWritingOffTheEnd(const ASTContext & Ctx,const LValue & LVal)11332 static bool isUserWritingOffTheEnd(const ASTContext &Ctx, const LValue &LVal) {
11333 const SubobjectDesignator &Designator = LVal.Designator;
11334 // Notes:
11335 // - Users can only write off of the end when we have an invalid base. Invalid
11336 // bases imply we don't know where the memory came from.
11337 // - We used to be a bit more aggressive here; we'd only be conservative if
11338 // the array at the end was flexible, or if it had 0 or 1 elements. This
11339 // broke some common standard library extensions (PR30346), but was
11340 // otherwise seemingly fine. It may be useful to reintroduce this behavior
11341 // with some sort of list. OTOH, it seems that GCC is always
11342 // conservative with the last element in structs (if it's an array), so our
11343 // current behavior is more compatible than an explicit list approach would
11344 // be.
11345 return LVal.InvalidBase &&
11346 Designator.Entries.size() == Designator.MostDerivedPathLength &&
11347 Designator.MostDerivedIsArrayElement &&
11348 isDesignatorAtObjectEnd(Ctx, LVal);
11349 }
11350
11351 /// Converts the given APInt to CharUnits, assuming the APInt is unsigned.
11352 /// Fails if the conversion would cause loss of precision.
convertUnsignedAPIntToCharUnits(const llvm::APInt & Int,CharUnits & Result)11353 static bool convertUnsignedAPIntToCharUnits(const llvm::APInt &Int,
11354 CharUnits &Result) {
11355 auto CharUnitsMax = std::numeric_limits<CharUnits::QuantityType>::max();
11356 if (Int.ugt(CharUnitsMax))
11357 return false;
11358 Result = CharUnits::fromQuantity(Int.getZExtValue());
11359 return true;
11360 }
11361
11362 /// Helper for tryEvaluateBuiltinObjectSize -- Given an LValue, this will
11363 /// determine how many bytes exist from the beginning of the object to either
11364 /// the end of the current subobject, or the end of the object itself, depending
11365 /// on what the LValue looks like + the value of Type.
11366 ///
11367 /// If this returns false, the value of Result is undefined.
determineEndOffset(EvalInfo & Info,SourceLocation ExprLoc,unsigned Type,const LValue & LVal,CharUnits & EndOffset)11368 static bool determineEndOffset(EvalInfo &Info, SourceLocation ExprLoc,
11369 unsigned Type, const LValue &LVal,
11370 CharUnits &EndOffset) {
11371 bool DetermineForCompleteObject = refersToCompleteObject(LVal);
11372
11373 auto CheckedHandleSizeof = [&](QualType Ty, CharUnits &Result) {
11374 if (Ty.isNull() || Ty->isIncompleteType() || Ty->isFunctionType())
11375 return false;
11376 return HandleSizeof(Info, ExprLoc, Ty, Result);
11377 };
11378
11379 // We want to evaluate the size of the entire object. This is a valid fallback
11380 // for when Type=1 and the designator is invalid, because we're asked for an
11381 // upper-bound.
11382 if (!(Type & 1) || LVal.Designator.Invalid || DetermineForCompleteObject) {
11383 // Type=3 wants a lower bound, so we can't fall back to this.
11384 if (Type == 3 && !DetermineForCompleteObject)
11385 return false;
11386
11387 llvm::APInt APEndOffset;
11388 if (isBaseAnAllocSizeCall(LVal.getLValueBase()) &&
11389 getBytesReturnedByAllocSizeCall(Info.Ctx, LVal, APEndOffset))
11390 return convertUnsignedAPIntToCharUnits(APEndOffset, EndOffset);
11391
11392 if (LVal.InvalidBase)
11393 return false;
11394
11395 QualType BaseTy = getObjectType(LVal.getLValueBase());
11396 return CheckedHandleSizeof(BaseTy, EndOffset);
11397 }
11398
11399 // We want to evaluate the size of a subobject.
11400 const SubobjectDesignator &Designator = LVal.Designator;
11401
11402 // The following is a moderately common idiom in C:
11403 //
11404 // struct Foo { int a; char c[1]; };
11405 // struct Foo *F = (struct Foo *)malloc(sizeof(struct Foo) + strlen(Bar));
11406 // strcpy(&F->c[0], Bar);
11407 //
11408 // In order to not break too much legacy code, we need to support it.
11409 if (isUserWritingOffTheEnd(Info.Ctx, LVal)) {
11410 // If we can resolve this to an alloc_size call, we can hand that back,
11411 // because we know for certain how many bytes there are to write to.
11412 llvm::APInt APEndOffset;
11413 if (isBaseAnAllocSizeCall(LVal.getLValueBase()) &&
11414 getBytesReturnedByAllocSizeCall(Info.Ctx, LVal, APEndOffset))
11415 return convertUnsignedAPIntToCharUnits(APEndOffset, EndOffset);
11416
11417 // If we cannot determine the size of the initial allocation, then we can't
11418 // given an accurate upper-bound. However, we are still able to give
11419 // conservative lower-bounds for Type=3.
11420 if (Type == 1)
11421 return false;
11422 }
11423
11424 CharUnits BytesPerElem;
11425 if (!CheckedHandleSizeof(Designator.MostDerivedType, BytesPerElem))
11426 return false;
11427
11428 // According to the GCC documentation, we want the size of the subobject
11429 // denoted by the pointer. But that's not quite right -- what we actually
11430 // want is the size of the immediately-enclosing array, if there is one.
11431 int64_t ElemsRemaining;
11432 if (Designator.MostDerivedIsArrayElement &&
11433 Designator.Entries.size() == Designator.MostDerivedPathLength) {
11434 uint64_t ArraySize = Designator.getMostDerivedArraySize();
11435 uint64_t ArrayIndex = Designator.Entries.back().getAsArrayIndex();
11436 ElemsRemaining = ArraySize <= ArrayIndex ? 0 : ArraySize - ArrayIndex;
11437 } else {
11438 ElemsRemaining = Designator.isOnePastTheEnd() ? 0 : 1;
11439 }
11440
11441 EndOffset = LVal.getLValueOffset() + BytesPerElem * ElemsRemaining;
11442 return true;
11443 }
11444
11445 /// Tries to evaluate the __builtin_object_size for @p E. If successful,
11446 /// returns true and stores the result in @p Size.
11447 ///
11448 /// If @p WasError is non-null, this will report whether the failure to evaluate
11449 /// is to be treated as an Error in IntExprEvaluator.
tryEvaluateBuiltinObjectSize(const Expr * E,unsigned Type,EvalInfo & Info,uint64_t & Size)11450 static bool tryEvaluateBuiltinObjectSize(const Expr *E, unsigned Type,
11451 EvalInfo &Info, uint64_t &Size) {
11452 // Determine the denoted object.
11453 LValue LVal;
11454 {
11455 // The operand of __builtin_object_size is never evaluated for side-effects.
11456 // If there are any, but we can determine the pointed-to object anyway, then
11457 // ignore the side-effects.
11458 SpeculativeEvaluationRAII SpeculativeEval(Info);
11459 IgnoreSideEffectsRAII Fold(Info);
11460
11461 if (E->isGLValue()) {
11462 // It's possible for us to be given GLValues if we're called via
11463 // Expr::tryEvaluateObjectSize.
11464 APValue RVal;
11465 if (!EvaluateAsRValue(Info, E, RVal))
11466 return false;
11467 LVal.setFrom(Info.Ctx, RVal);
11468 } else if (!EvaluatePointer(ignorePointerCastsAndParens(E), LVal, Info,
11469 /*InvalidBaseOK=*/true))
11470 return false;
11471 }
11472
11473 // If we point to before the start of the object, there are no accessible
11474 // bytes.
11475 if (LVal.getLValueOffset().isNegative()) {
11476 Size = 0;
11477 return true;
11478 }
11479
11480 CharUnits EndOffset;
11481 if (!determineEndOffset(Info, E->getExprLoc(), Type, LVal, EndOffset))
11482 return false;
11483
11484 // If we've fallen outside of the end offset, just pretend there's nothing to
11485 // write to/read from.
11486 if (EndOffset <= LVal.getLValueOffset())
11487 Size = 0;
11488 else
11489 Size = (EndOffset - LVal.getLValueOffset()).getQuantity();
11490 return true;
11491 }
11492
VisitCallExpr(const CallExpr * E)11493 bool IntExprEvaluator::VisitCallExpr(const CallExpr *E) {
11494 if (unsigned BuiltinOp = E->getBuiltinCallee())
11495 return VisitBuiltinCallExpr(E, BuiltinOp);
11496
11497 return ExprEvaluatorBaseTy::VisitCallExpr(E);
11498 }
11499
getBuiltinAlignArguments(const CallExpr * E,EvalInfo & Info,APValue & Val,APSInt & Alignment)11500 static bool getBuiltinAlignArguments(const CallExpr *E, EvalInfo &Info,
11501 APValue &Val, APSInt &Alignment) {
11502 QualType SrcTy = E->getArg(0)->getType();
11503 if (!getAlignmentArgument(E->getArg(1), SrcTy, Info, Alignment))
11504 return false;
11505 // Even though we are evaluating integer expressions we could get a pointer
11506 // argument for the __builtin_is_aligned() case.
11507 if (SrcTy->isPointerType()) {
11508 LValue Ptr;
11509 if (!EvaluatePointer(E->getArg(0), Ptr, Info))
11510 return false;
11511 Ptr.moveInto(Val);
11512 } else if (!SrcTy->isIntegralOrEnumerationType()) {
11513 Info.FFDiag(E->getArg(0));
11514 return false;
11515 } else {
11516 APSInt SrcInt;
11517 if (!EvaluateInteger(E->getArg(0), SrcInt, Info))
11518 return false;
11519 assert(SrcInt.getBitWidth() >= Alignment.getBitWidth() &&
11520 "Bit widths must be the same");
11521 Val = APValue(SrcInt);
11522 }
11523 assert(Val.hasValue());
11524 return true;
11525 }
11526
VisitBuiltinCallExpr(const CallExpr * E,unsigned BuiltinOp)11527 bool IntExprEvaluator::VisitBuiltinCallExpr(const CallExpr *E,
11528 unsigned BuiltinOp) {
11529 switch (BuiltinOp) {
11530 default:
11531 return ExprEvaluatorBaseTy::VisitCallExpr(E);
11532
11533 case Builtin::BI__builtin_dynamic_object_size:
11534 case Builtin::BI__builtin_object_size: {
11535 // The type was checked when we built the expression.
11536 unsigned Type =
11537 E->getArg(1)->EvaluateKnownConstInt(Info.Ctx).getZExtValue();
11538 assert(Type <= 3 && "unexpected type");
11539
11540 uint64_t Size;
11541 if (tryEvaluateBuiltinObjectSize(E->getArg(0), Type, Info, Size))
11542 return Success(Size, E);
11543
11544 if (E->getArg(0)->HasSideEffects(Info.Ctx))
11545 return Success((Type & 2) ? 0 : -1, E);
11546
11547 // Expression had no side effects, but we couldn't statically determine the
11548 // size of the referenced object.
11549 switch (Info.EvalMode) {
11550 case EvalInfo::EM_ConstantExpression:
11551 case EvalInfo::EM_ConstantFold:
11552 case EvalInfo::EM_IgnoreSideEffects:
11553 // Leave it to IR generation.
11554 return Error(E);
11555 case EvalInfo::EM_ConstantExpressionUnevaluated:
11556 // Reduce it to a constant now.
11557 return Success((Type & 2) ? 0 : -1, E);
11558 }
11559
11560 llvm_unreachable("unexpected EvalMode");
11561 }
11562
11563 case Builtin::BI__builtin_os_log_format_buffer_size: {
11564 analyze_os_log::OSLogBufferLayout Layout;
11565 analyze_os_log::computeOSLogBufferLayout(Info.Ctx, E, Layout);
11566 return Success(Layout.size().getQuantity(), E);
11567 }
11568
11569 case Builtin::BI__builtin_is_aligned: {
11570 APValue Src;
11571 APSInt Alignment;
11572 if (!getBuiltinAlignArguments(E, Info, Src, Alignment))
11573 return false;
11574 if (Src.isLValue()) {
11575 // If we evaluated a pointer, check the minimum known alignment.
11576 LValue Ptr;
11577 Ptr.setFrom(Info.Ctx, Src);
11578 CharUnits BaseAlignment = getBaseAlignment(Info, Ptr);
11579 CharUnits PtrAlign = BaseAlignment.alignmentAtOffset(Ptr.Offset);
11580 // We can return true if the known alignment at the computed offset is
11581 // greater than the requested alignment.
11582 assert(PtrAlign.isPowerOfTwo());
11583 assert(Alignment.isPowerOf2());
11584 if (PtrAlign.getQuantity() >= Alignment)
11585 return Success(1, E);
11586 // If the alignment is not known to be sufficient, some cases could still
11587 // be aligned at run time. However, if the requested alignment is less or
11588 // equal to the base alignment and the offset is not aligned, we know that
11589 // the run-time value can never be aligned.
11590 if (BaseAlignment.getQuantity() >= Alignment &&
11591 PtrAlign.getQuantity() < Alignment)
11592 return Success(0, E);
11593 // Otherwise we can't infer whether the value is sufficiently aligned.
11594 // TODO: __builtin_is_aligned(__builtin_align_{down,up{(expr, N), N)
11595 // in cases where we can't fully evaluate the pointer.
11596 Info.FFDiag(E->getArg(0), diag::note_constexpr_alignment_compute)
11597 << Alignment;
11598 return false;
11599 }
11600 assert(Src.isInt());
11601 return Success((Src.getInt() & (Alignment - 1)) == 0 ? 1 : 0, E);
11602 }
11603 case Builtin::BI__builtin_align_up: {
11604 APValue Src;
11605 APSInt Alignment;
11606 if (!getBuiltinAlignArguments(E, Info, Src, Alignment))
11607 return false;
11608 if (!Src.isInt())
11609 return Error(E);
11610 APSInt AlignedVal =
11611 APSInt((Src.getInt() + (Alignment - 1)) & ~(Alignment - 1),
11612 Src.getInt().isUnsigned());
11613 assert(AlignedVal.getBitWidth() == Src.getInt().getBitWidth());
11614 return Success(AlignedVal, E);
11615 }
11616 case Builtin::BI__builtin_align_down: {
11617 APValue Src;
11618 APSInt Alignment;
11619 if (!getBuiltinAlignArguments(E, Info, Src, Alignment))
11620 return false;
11621 if (!Src.isInt())
11622 return Error(E);
11623 APSInt AlignedVal =
11624 APSInt(Src.getInt() & ~(Alignment - 1), Src.getInt().isUnsigned());
11625 assert(AlignedVal.getBitWidth() == Src.getInt().getBitWidth());
11626 return Success(AlignedVal, E);
11627 }
11628
11629 case Builtin::BI__builtin_bitreverse8:
11630 case Builtin::BI__builtin_bitreverse16:
11631 case Builtin::BI__builtin_bitreverse32:
11632 case Builtin::BI__builtin_bitreverse64: {
11633 APSInt Val;
11634 if (!EvaluateInteger(E->getArg(0), Val, Info))
11635 return false;
11636
11637 return Success(Val.reverseBits(), E);
11638 }
11639
11640 case Builtin::BI__builtin_bswap16:
11641 case Builtin::BI__builtin_bswap32:
11642 case Builtin::BI__builtin_bswap64: {
11643 APSInt Val;
11644 if (!EvaluateInteger(E->getArg(0), Val, Info))
11645 return false;
11646
11647 return Success(Val.byteSwap(), E);
11648 }
11649
11650 case Builtin::BI__builtin_classify_type:
11651 return Success((int)EvaluateBuiltinClassifyType(E, Info.getLangOpts()), E);
11652
11653 case Builtin::BI__builtin_clrsb:
11654 case Builtin::BI__builtin_clrsbl:
11655 case Builtin::BI__builtin_clrsbll: {
11656 APSInt Val;
11657 if (!EvaluateInteger(E->getArg(0), Val, Info))
11658 return false;
11659
11660 return Success(Val.getBitWidth() - Val.getMinSignedBits(), E);
11661 }
11662
11663 case Builtin::BI__builtin_clz:
11664 case Builtin::BI__builtin_clzl:
11665 case Builtin::BI__builtin_clzll:
11666 case Builtin::BI__builtin_clzs: {
11667 APSInt Val;
11668 if (!EvaluateInteger(E->getArg(0), Val, Info))
11669 return false;
11670 if (!Val)
11671 return Error(E);
11672
11673 return Success(Val.countLeadingZeros(), E);
11674 }
11675
11676 case Builtin::BI__builtin_constant_p: {
11677 const Expr *Arg = E->getArg(0);
11678 if (EvaluateBuiltinConstantP(Info, Arg))
11679 return Success(true, E);
11680 if (Info.InConstantContext || Arg->HasSideEffects(Info.Ctx)) {
11681 // Outside a constant context, eagerly evaluate to false in the presence
11682 // of side-effects in order to avoid -Wunsequenced false-positives in
11683 // a branch on __builtin_constant_p(expr).
11684 return Success(false, E);
11685 }
11686 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
11687 return false;
11688 }
11689
11690 case Builtin::BI__builtin_is_constant_evaluated: {
11691 const auto *Callee = Info.CurrentCall->getCallee();
11692 if (Info.InConstantContext && !Info.CheckingPotentialConstantExpression &&
11693 (Info.CallStackDepth == 1 ||
11694 (Info.CallStackDepth == 2 && Callee->isInStdNamespace() &&
11695 Callee->getIdentifier() &&
11696 Callee->getIdentifier()->isStr("is_constant_evaluated")))) {
11697 // FIXME: Find a better way to avoid duplicated diagnostics.
11698 if (Info.EvalStatus.Diag)
11699 Info.report((Info.CallStackDepth == 1) ? E->getExprLoc()
11700 : Info.CurrentCall->CallLoc,
11701 diag::warn_is_constant_evaluated_always_true_constexpr)
11702 << (Info.CallStackDepth == 1 ? "__builtin_is_constant_evaluated"
11703 : "std::is_constant_evaluated");
11704 }
11705
11706 return Success(Info.InConstantContext, E);
11707 }
11708
11709 case Builtin::BI__builtin_ctz:
11710 case Builtin::BI__builtin_ctzl:
11711 case Builtin::BI__builtin_ctzll:
11712 case Builtin::BI__builtin_ctzs: {
11713 APSInt Val;
11714 if (!EvaluateInteger(E->getArg(0), Val, Info))
11715 return false;
11716 if (!Val)
11717 return Error(E);
11718
11719 return Success(Val.countTrailingZeros(), E);
11720 }
11721
11722 case Builtin::BI__builtin_eh_return_data_regno: {
11723 int Operand = E->getArg(0)->EvaluateKnownConstInt(Info.Ctx).getZExtValue();
11724 Operand = Info.Ctx.getTargetInfo().getEHDataRegisterNumber(Operand);
11725 return Success(Operand, E);
11726 }
11727
11728 case Builtin::BI__builtin_expect:
11729 case Builtin::BI__builtin_expect_with_probability:
11730 return Visit(E->getArg(0));
11731
11732 case Builtin::BI__builtin_ffs:
11733 case Builtin::BI__builtin_ffsl:
11734 case Builtin::BI__builtin_ffsll: {
11735 APSInt Val;
11736 if (!EvaluateInteger(E->getArg(0), Val, Info))
11737 return false;
11738
11739 unsigned N = Val.countTrailingZeros();
11740 return Success(N == Val.getBitWidth() ? 0 : N + 1, E);
11741 }
11742
11743 case Builtin::BI__builtin_fpclassify: {
11744 APFloat Val(0.0);
11745 if (!EvaluateFloat(E->getArg(5), Val, Info))
11746 return false;
11747 unsigned Arg;
11748 switch (Val.getCategory()) {
11749 case APFloat::fcNaN: Arg = 0; break;
11750 case APFloat::fcInfinity: Arg = 1; break;
11751 case APFloat::fcNormal: Arg = Val.isDenormal() ? 3 : 2; break;
11752 case APFloat::fcZero: Arg = 4; break;
11753 }
11754 return Visit(E->getArg(Arg));
11755 }
11756
11757 case Builtin::BI__builtin_isinf_sign: {
11758 APFloat Val(0.0);
11759 return EvaluateFloat(E->getArg(0), Val, Info) &&
11760 Success(Val.isInfinity() ? (Val.isNegative() ? -1 : 1) : 0, E);
11761 }
11762
11763 case Builtin::BI__builtin_isinf: {
11764 APFloat Val(0.0);
11765 return EvaluateFloat(E->getArg(0), Val, Info) &&
11766 Success(Val.isInfinity() ? 1 : 0, E);
11767 }
11768
11769 case Builtin::BI__builtin_isfinite: {
11770 APFloat Val(0.0);
11771 return EvaluateFloat(E->getArg(0), Val, Info) &&
11772 Success(Val.isFinite() ? 1 : 0, E);
11773 }
11774
11775 case Builtin::BI__builtin_isnan: {
11776 APFloat Val(0.0);
11777 return EvaluateFloat(E->getArg(0), Val, Info) &&
11778 Success(Val.isNaN() ? 1 : 0, E);
11779 }
11780
11781 case Builtin::BI__builtin_isnormal: {
11782 APFloat Val(0.0);
11783 return EvaluateFloat(E->getArg(0), Val, Info) &&
11784 Success(Val.isNormal() ? 1 : 0, E);
11785 }
11786
11787 case Builtin::BI__builtin_parity:
11788 case Builtin::BI__builtin_parityl:
11789 case Builtin::BI__builtin_parityll: {
11790 APSInt Val;
11791 if (!EvaluateInteger(E->getArg(0), Val, Info))
11792 return false;
11793
11794 return Success(Val.countPopulation() % 2, E);
11795 }
11796
11797 case Builtin::BI__builtin_popcount:
11798 case Builtin::BI__builtin_popcountl:
11799 case Builtin::BI__builtin_popcountll: {
11800 APSInt Val;
11801 if (!EvaluateInteger(E->getArg(0), Val, Info))
11802 return false;
11803
11804 return Success(Val.countPopulation(), E);
11805 }
11806
11807 case Builtin::BI__builtin_rotateleft8:
11808 case Builtin::BI__builtin_rotateleft16:
11809 case Builtin::BI__builtin_rotateleft32:
11810 case Builtin::BI__builtin_rotateleft64:
11811 case Builtin::BI_rotl8: // Microsoft variants of rotate right
11812 case Builtin::BI_rotl16:
11813 case Builtin::BI_rotl:
11814 case Builtin::BI_lrotl:
11815 case Builtin::BI_rotl64: {
11816 APSInt Val, Amt;
11817 if (!EvaluateInteger(E->getArg(0), Val, Info) ||
11818 !EvaluateInteger(E->getArg(1), Amt, Info))
11819 return false;
11820
11821 return Success(Val.rotl(Amt.urem(Val.getBitWidth())), E);
11822 }
11823
11824 case Builtin::BI__builtin_rotateright8:
11825 case Builtin::BI__builtin_rotateright16:
11826 case Builtin::BI__builtin_rotateright32:
11827 case Builtin::BI__builtin_rotateright64:
11828 case Builtin::BI_rotr8: // Microsoft variants of rotate right
11829 case Builtin::BI_rotr16:
11830 case Builtin::BI_rotr:
11831 case Builtin::BI_lrotr:
11832 case Builtin::BI_rotr64: {
11833 APSInt Val, Amt;
11834 if (!EvaluateInteger(E->getArg(0), Val, Info) ||
11835 !EvaluateInteger(E->getArg(1), Amt, Info))
11836 return false;
11837
11838 return Success(Val.rotr(Amt.urem(Val.getBitWidth())), E);
11839 }
11840
11841 case Builtin::BIstrlen:
11842 case Builtin::BIwcslen:
11843 // A call to strlen is not a constant expression.
11844 if (Info.getLangOpts().CPlusPlus11)
11845 Info.CCEDiag(E, diag::note_constexpr_invalid_function)
11846 << /*isConstexpr*/0 << /*isConstructor*/0
11847 << (std::string("'") + Info.Ctx.BuiltinInfo.getName(BuiltinOp) + "'");
11848 else
11849 Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr);
11850 LLVM_FALLTHROUGH;
11851 case Builtin::BI__builtin_strlen:
11852 case Builtin::BI__builtin_wcslen: {
11853 // As an extension, we support __builtin_strlen() as a constant expression,
11854 // and support folding strlen() to a constant.
11855 uint64_t StrLen;
11856 if (EvaluateBuiltinStrLen(E->getArg(0), StrLen, Info))
11857 return Success(StrLen, E);
11858 return false;
11859 }
11860
11861 case Builtin::BIstrcmp:
11862 case Builtin::BIwcscmp:
11863 case Builtin::BIstrncmp:
11864 case Builtin::BIwcsncmp:
11865 case Builtin::BImemcmp:
11866 case Builtin::BIbcmp:
11867 case Builtin::BIwmemcmp:
11868 // A call to strlen is not a constant expression.
11869 if (Info.getLangOpts().CPlusPlus11)
11870 Info.CCEDiag(E, diag::note_constexpr_invalid_function)
11871 << /*isConstexpr*/0 << /*isConstructor*/0
11872 << (std::string("'") + Info.Ctx.BuiltinInfo.getName(BuiltinOp) + "'");
11873 else
11874 Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr);
11875 LLVM_FALLTHROUGH;
11876 case Builtin::BI__builtin_strcmp:
11877 case Builtin::BI__builtin_wcscmp:
11878 case Builtin::BI__builtin_strncmp:
11879 case Builtin::BI__builtin_wcsncmp:
11880 case Builtin::BI__builtin_memcmp:
11881 case Builtin::BI__builtin_bcmp:
11882 case Builtin::BI__builtin_wmemcmp: {
11883 LValue String1, String2;
11884 if (!EvaluatePointer(E->getArg(0), String1, Info) ||
11885 !EvaluatePointer(E->getArg(1), String2, Info))
11886 return false;
11887
11888 uint64_t MaxLength = uint64_t(-1);
11889 if (BuiltinOp != Builtin::BIstrcmp &&
11890 BuiltinOp != Builtin::BIwcscmp &&
11891 BuiltinOp != Builtin::BI__builtin_strcmp &&
11892 BuiltinOp != Builtin::BI__builtin_wcscmp) {
11893 APSInt N;
11894 if (!EvaluateInteger(E->getArg(2), N, Info))
11895 return false;
11896 MaxLength = N.getExtValue();
11897 }
11898
11899 // Empty substrings compare equal by definition.
11900 if (MaxLength == 0u)
11901 return Success(0, E);
11902
11903 if (!String1.checkNullPointerForFoldAccess(Info, E, AK_Read) ||
11904 !String2.checkNullPointerForFoldAccess(Info, E, AK_Read) ||
11905 String1.Designator.Invalid || String2.Designator.Invalid)
11906 return false;
11907
11908 QualType CharTy1 = String1.Designator.getType(Info.Ctx);
11909 QualType CharTy2 = String2.Designator.getType(Info.Ctx);
11910
11911 bool IsRawByte = BuiltinOp == Builtin::BImemcmp ||
11912 BuiltinOp == Builtin::BIbcmp ||
11913 BuiltinOp == Builtin::BI__builtin_memcmp ||
11914 BuiltinOp == Builtin::BI__builtin_bcmp;
11915
11916 assert(IsRawByte ||
11917 (Info.Ctx.hasSameUnqualifiedType(
11918 CharTy1, E->getArg(0)->getType()->getPointeeType()) &&
11919 Info.Ctx.hasSameUnqualifiedType(CharTy1, CharTy2)));
11920
11921 // For memcmp, allow comparing any arrays of '[[un]signed] char' or
11922 // 'char8_t', but no other types.
11923 if (IsRawByte &&
11924 !(isOneByteCharacterType(CharTy1) && isOneByteCharacterType(CharTy2))) {
11925 // FIXME: Consider using our bit_cast implementation to support this.
11926 Info.FFDiag(E, diag::note_constexpr_memcmp_unsupported)
11927 << (std::string("'") + Info.Ctx.BuiltinInfo.getName(BuiltinOp) + "'")
11928 << CharTy1 << CharTy2;
11929 return false;
11930 }
11931
11932 const auto &ReadCurElems = [&](APValue &Char1, APValue &Char2) {
11933 return handleLValueToRValueConversion(Info, E, CharTy1, String1, Char1) &&
11934 handleLValueToRValueConversion(Info, E, CharTy2, String2, Char2) &&
11935 Char1.isInt() && Char2.isInt();
11936 };
11937 const auto &AdvanceElems = [&] {
11938 return HandleLValueArrayAdjustment(Info, E, String1, CharTy1, 1) &&
11939 HandleLValueArrayAdjustment(Info, E, String2, CharTy2, 1);
11940 };
11941
11942 bool StopAtNull =
11943 (BuiltinOp != Builtin::BImemcmp && BuiltinOp != Builtin::BIbcmp &&
11944 BuiltinOp != Builtin::BIwmemcmp &&
11945 BuiltinOp != Builtin::BI__builtin_memcmp &&
11946 BuiltinOp != Builtin::BI__builtin_bcmp &&
11947 BuiltinOp != Builtin::BI__builtin_wmemcmp);
11948 bool IsWide = BuiltinOp == Builtin::BIwcscmp ||
11949 BuiltinOp == Builtin::BIwcsncmp ||
11950 BuiltinOp == Builtin::BIwmemcmp ||
11951 BuiltinOp == Builtin::BI__builtin_wcscmp ||
11952 BuiltinOp == Builtin::BI__builtin_wcsncmp ||
11953 BuiltinOp == Builtin::BI__builtin_wmemcmp;
11954
11955 for (; MaxLength; --MaxLength) {
11956 APValue Char1, Char2;
11957 if (!ReadCurElems(Char1, Char2))
11958 return false;
11959 if (Char1.getInt().ne(Char2.getInt())) {
11960 if (IsWide) // wmemcmp compares with wchar_t signedness.
11961 return Success(Char1.getInt() < Char2.getInt() ? -1 : 1, E);
11962 // memcmp always compares unsigned chars.
11963 return Success(Char1.getInt().ult(Char2.getInt()) ? -1 : 1, E);
11964 }
11965 if (StopAtNull && !Char1.getInt())
11966 return Success(0, E);
11967 assert(!(StopAtNull && !Char2.getInt()));
11968 if (!AdvanceElems())
11969 return false;
11970 }
11971 // We hit the strncmp / memcmp limit.
11972 return Success(0, E);
11973 }
11974
11975 case Builtin::BI__atomic_always_lock_free:
11976 case Builtin::BI__atomic_is_lock_free:
11977 case Builtin::BI__c11_atomic_is_lock_free: {
11978 APSInt SizeVal;
11979 if (!EvaluateInteger(E->getArg(0), SizeVal, Info))
11980 return false;
11981
11982 // For __atomic_is_lock_free(sizeof(_Atomic(T))), if the size is a power
11983 // of two less than or equal to the maximum inline atomic width, we know it
11984 // is lock-free. If the size isn't a power of two, or greater than the
11985 // maximum alignment where we promote atomics, we know it is not lock-free
11986 // (at least not in the sense of atomic_is_lock_free). Otherwise,
11987 // the answer can only be determined at runtime; for example, 16-byte
11988 // atomics have lock-free implementations on some, but not all,
11989 // x86-64 processors.
11990
11991 // Check power-of-two.
11992 CharUnits Size = CharUnits::fromQuantity(SizeVal.getZExtValue());
11993 if (Size.isPowerOfTwo()) {
11994 // Check against inlining width.
11995 unsigned InlineWidthBits =
11996 Info.Ctx.getTargetInfo().getMaxAtomicInlineWidth();
11997 if (Size <= Info.Ctx.toCharUnitsFromBits(InlineWidthBits)) {
11998 if (BuiltinOp == Builtin::BI__c11_atomic_is_lock_free ||
11999 Size == CharUnits::One() ||
12000 E->getArg(1)->isNullPointerConstant(Info.Ctx,
12001 Expr::NPC_NeverValueDependent))
12002 // OK, we will inline appropriately-aligned operations of this size,
12003 // and _Atomic(T) is appropriately-aligned.
12004 return Success(1, E);
12005
12006 QualType PointeeType = E->getArg(1)->IgnoreImpCasts()->getType()->
12007 castAs<PointerType>()->getPointeeType();
12008 if (!PointeeType->isIncompleteType() &&
12009 Info.Ctx.getTypeAlignInChars(PointeeType) >= Size) {
12010 // OK, we will inline operations on this object.
12011 return Success(1, E);
12012 }
12013 }
12014 }
12015
12016 return BuiltinOp == Builtin::BI__atomic_always_lock_free ?
12017 Success(0, E) : Error(E);
12018 }
12019 case Builtin::BI__builtin_add_overflow:
12020 case Builtin::BI__builtin_sub_overflow:
12021 case Builtin::BI__builtin_mul_overflow:
12022 case Builtin::BI__builtin_sadd_overflow:
12023 case Builtin::BI__builtin_uadd_overflow:
12024 case Builtin::BI__builtin_uaddl_overflow:
12025 case Builtin::BI__builtin_uaddll_overflow:
12026 case Builtin::BI__builtin_usub_overflow:
12027 case Builtin::BI__builtin_usubl_overflow:
12028 case Builtin::BI__builtin_usubll_overflow:
12029 case Builtin::BI__builtin_umul_overflow:
12030 case Builtin::BI__builtin_umull_overflow:
12031 case Builtin::BI__builtin_umulll_overflow:
12032 case Builtin::BI__builtin_saddl_overflow:
12033 case Builtin::BI__builtin_saddll_overflow:
12034 case Builtin::BI__builtin_ssub_overflow:
12035 case Builtin::BI__builtin_ssubl_overflow:
12036 case Builtin::BI__builtin_ssubll_overflow:
12037 case Builtin::BI__builtin_smul_overflow:
12038 case Builtin::BI__builtin_smull_overflow:
12039 case Builtin::BI__builtin_smulll_overflow: {
12040 LValue ResultLValue;
12041 APSInt LHS, RHS;
12042
12043 QualType ResultType = E->getArg(2)->getType()->getPointeeType();
12044 if (!EvaluateInteger(E->getArg(0), LHS, Info) ||
12045 !EvaluateInteger(E->getArg(1), RHS, Info) ||
12046 !EvaluatePointer(E->getArg(2), ResultLValue, Info))
12047 return false;
12048
12049 APSInt Result;
12050 bool DidOverflow = false;
12051
12052 // If the types don't have to match, enlarge all 3 to the largest of them.
12053 if (BuiltinOp == Builtin::BI__builtin_add_overflow ||
12054 BuiltinOp == Builtin::BI__builtin_sub_overflow ||
12055 BuiltinOp == Builtin::BI__builtin_mul_overflow) {
12056 bool IsSigned = LHS.isSigned() || RHS.isSigned() ||
12057 ResultType->isSignedIntegerOrEnumerationType();
12058 bool AllSigned = LHS.isSigned() && RHS.isSigned() &&
12059 ResultType->isSignedIntegerOrEnumerationType();
12060 uint64_t LHSSize = LHS.getBitWidth();
12061 uint64_t RHSSize = RHS.getBitWidth();
12062 uint64_t ResultSize = Info.Ctx.getTypeSize(ResultType);
12063 uint64_t MaxBits = std::max(std::max(LHSSize, RHSSize), ResultSize);
12064
12065 // Add an additional bit if the signedness isn't uniformly agreed to. We
12066 // could do this ONLY if there is a signed and an unsigned that both have
12067 // MaxBits, but the code to check that is pretty nasty. The issue will be
12068 // caught in the shrink-to-result later anyway.
12069 if (IsSigned && !AllSigned)
12070 ++MaxBits;
12071
12072 LHS = APSInt(LHS.extOrTrunc(MaxBits), !IsSigned);
12073 RHS = APSInt(RHS.extOrTrunc(MaxBits), !IsSigned);
12074 Result = APSInt(MaxBits, !IsSigned);
12075 }
12076
12077 // Find largest int.
12078 switch (BuiltinOp) {
12079 default:
12080 llvm_unreachable("Invalid value for BuiltinOp");
12081 case Builtin::BI__builtin_add_overflow:
12082 case Builtin::BI__builtin_sadd_overflow:
12083 case Builtin::BI__builtin_saddl_overflow:
12084 case Builtin::BI__builtin_saddll_overflow:
12085 case Builtin::BI__builtin_uadd_overflow:
12086 case Builtin::BI__builtin_uaddl_overflow:
12087 case Builtin::BI__builtin_uaddll_overflow:
12088 Result = LHS.isSigned() ? LHS.sadd_ov(RHS, DidOverflow)
12089 : LHS.uadd_ov(RHS, DidOverflow);
12090 break;
12091 case Builtin::BI__builtin_sub_overflow:
12092 case Builtin::BI__builtin_ssub_overflow:
12093 case Builtin::BI__builtin_ssubl_overflow:
12094 case Builtin::BI__builtin_ssubll_overflow:
12095 case Builtin::BI__builtin_usub_overflow:
12096 case Builtin::BI__builtin_usubl_overflow:
12097 case Builtin::BI__builtin_usubll_overflow:
12098 Result = LHS.isSigned() ? LHS.ssub_ov(RHS, DidOverflow)
12099 : LHS.usub_ov(RHS, DidOverflow);
12100 break;
12101 case Builtin::BI__builtin_mul_overflow:
12102 case Builtin::BI__builtin_smul_overflow:
12103 case Builtin::BI__builtin_smull_overflow:
12104 case Builtin::BI__builtin_smulll_overflow:
12105 case Builtin::BI__builtin_umul_overflow:
12106 case Builtin::BI__builtin_umull_overflow:
12107 case Builtin::BI__builtin_umulll_overflow:
12108 Result = LHS.isSigned() ? LHS.smul_ov(RHS, DidOverflow)
12109 : LHS.umul_ov(RHS, DidOverflow);
12110 break;
12111 }
12112
12113 // In the case where multiple sizes are allowed, truncate and see if
12114 // the values are the same.
12115 if (BuiltinOp == Builtin::BI__builtin_add_overflow ||
12116 BuiltinOp == Builtin::BI__builtin_sub_overflow ||
12117 BuiltinOp == Builtin::BI__builtin_mul_overflow) {
12118 // APSInt doesn't have a TruncOrSelf, so we use extOrTrunc instead,
12119 // since it will give us the behavior of a TruncOrSelf in the case where
12120 // its parameter <= its size. We previously set Result to be at least the
12121 // type-size of the result, so getTypeSize(ResultType) <= Result.BitWidth
12122 // will work exactly like TruncOrSelf.
12123 APSInt Temp = Result.extOrTrunc(Info.Ctx.getTypeSize(ResultType));
12124 Temp.setIsSigned(ResultType->isSignedIntegerOrEnumerationType());
12125
12126 if (!APSInt::isSameValue(Temp, Result))
12127 DidOverflow = true;
12128 Result = Temp;
12129 }
12130
12131 APValue APV{Result};
12132 if (!handleAssignment(Info, E, ResultLValue, ResultType, APV))
12133 return false;
12134 return Success(DidOverflow, E);
12135 }
12136 }
12137 }
12138
12139 /// Determine whether this is a pointer past the end of the complete
12140 /// object referred to by the lvalue.
isOnePastTheEndOfCompleteObject(const ASTContext & Ctx,const LValue & LV)12141 static bool isOnePastTheEndOfCompleteObject(const ASTContext &Ctx,
12142 const LValue &LV) {
12143 // A null pointer can be viewed as being "past the end" but we don't
12144 // choose to look at it that way here.
12145 if (!LV.getLValueBase())
12146 return false;
12147
12148 // If the designator is valid and refers to a subobject, we're not pointing
12149 // past the end.
12150 if (!LV.getLValueDesignator().Invalid &&
12151 !LV.getLValueDesignator().isOnePastTheEnd())
12152 return false;
12153
12154 // A pointer to an incomplete type might be past-the-end if the type's size is
12155 // zero. We cannot tell because the type is incomplete.
12156 QualType Ty = getType(LV.getLValueBase());
12157 if (Ty->isIncompleteType())
12158 return true;
12159
12160 // We're a past-the-end pointer if we point to the byte after the object,
12161 // no matter what our type or path is.
12162 auto Size = Ctx.getTypeSizeInChars(Ty);
12163 return LV.getLValueOffset() == Size;
12164 }
12165
12166 namespace {
12167
12168 /// Data recursive integer evaluator of certain binary operators.
12169 ///
12170 /// We use a data recursive algorithm for binary operators so that we are able
12171 /// to handle extreme cases of chained binary operators without causing stack
12172 /// overflow.
12173 class DataRecursiveIntBinOpEvaluator {
12174 struct EvalResult {
12175 APValue Val;
12176 bool Failed;
12177
EvalResult__anon4a4db2532811::DataRecursiveIntBinOpEvaluator::EvalResult12178 EvalResult() : Failed(false) { }
12179
swap__anon4a4db2532811::DataRecursiveIntBinOpEvaluator::EvalResult12180 void swap(EvalResult &RHS) {
12181 Val.swap(RHS.Val);
12182 Failed = RHS.Failed;
12183 RHS.Failed = false;
12184 }
12185 };
12186
12187 struct Job {
12188 const Expr *E;
12189 EvalResult LHSResult; // meaningful only for binary operator expression.
12190 enum { AnyExprKind, BinOpKind, BinOpVisitedLHSKind } Kind;
12191
12192 Job() = default;
12193 Job(Job &&) = default;
12194
startSpeculativeEval__anon4a4db2532811::DataRecursiveIntBinOpEvaluator::Job12195 void startSpeculativeEval(EvalInfo &Info) {
12196 SpecEvalRAII = SpeculativeEvaluationRAII(Info);
12197 }
12198
12199 private:
12200 SpeculativeEvaluationRAII SpecEvalRAII;
12201 };
12202
12203 SmallVector<Job, 16> Queue;
12204
12205 IntExprEvaluator &IntEval;
12206 EvalInfo &Info;
12207 APValue &FinalResult;
12208
12209 public:
DataRecursiveIntBinOpEvaluator(IntExprEvaluator & IntEval,APValue & Result)12210 DataRecursiveIntBinOpEvaluator(IntExprEvaluator &IntEval, APValue &Result)
12211 : IntEval(IntEval), Info(IntEval.getEvalInfo()), FinalResult(Result) { }
12212
12213 /// True if \param E is a binary operator that we are going to handle
12214 /// data recursively.
12215 /// We handle binary operators that are comma, logical, or that have operands
12216 /// with integral or enumeration type.
shouldEnqueue(const BinaryOperator * E)12217 static bool shouldEnqueue(const BinaryOperator *E) {
12218 return E->getOpcode() == BO_Comma || E->isLogicalOp() ||
12219 (E->isPRValue() && E->getType()->isIntegralOrEnumerationType() &&
12220 E->getLHS()->getType()->isIntegralOrEnumerationType() &&
12221 E->getRHS()->getType()->isIntegralOrEnumerationType());
12222 }
12223
Traverse(const BinaryOperator * E)12224 bool Traverse(const BinaryOperator *E) {
12225 enqueue(E);
12226 EvalResult PrevResult;
12227 while (!Queue.empty())
12228 process(PrevResult);
12229
12230 if (PrevResult.Failed) return false;
12231
12232 FinalResult.swap(PrevResult.Val);
12233 return true;
12234 }
12235
12236 private:
Success(uint64_t Value,const Expr * E,APValue & Result)12237 bool Success(uint64_t Value, const Expr *E, APValue &Result) {
12238 return IntEval.Success(Value, E, Result);
12239 }
Success(const APSInt & Value,const Expr * E,APValue & Result)12240 bool Success(const APSInt &Value, const Expr *E, APValue &Result) {
12241 return IntEval.Success(Value, E, Result);
12242 }
Error(const Expr * E)12243 bool Error(const Expr *E) {
12244 return IntEval.Error(E);
12245 }
Error(const Expr * E,diag::kind D)12246 bool Error(const Expr *E, diag::kind D) {
12247 return IntEval.Error(E, D);
12248 }
12249
CCEDiag(const Expr * E,diag::kind D)12250 OptionalDiagnostic CCEDiag(const Expr *E, diag::kind D) {
12251 return Info.CCEDiag(E, D);
12252 }
12253
12254 // Returns true if visiting the RHS is necessary, false otherwise.
12255 bool VisitBinOpLHSOnly(EvalResult &LHSResult, const BinaryOperator *E,
12256 bool &SuppressRHSDiags);
12257
12258 bool VisitBinOp(const EvalResult &LHSResult, const EvalResult &RHSResult,
12259 const BinaryOperator *E, APValue &Result);
12260
EvaluateExpr(const Expr * E,EvalResult & Result)12261 void EvaluateExpr(const Expr *E, EvalResult &Result) {
12262 Result.Failed = !Evaluate(Result.Val, Info, E);
12263 if (Result.Failed)
12264 Result.Val = APValue();
12265 }
12266
12267 void process(EvalResult &Result);
12268
enqueue(const Expr * E)12269 void enqueue(const Expr *E) {
12270 E = E->IgnoreParens();
12271 Queue.resize(Queue.size()+1);
12272 Queue.back().E = E;
12273 Queue.back().Kind = Job::AnyExprKind;
12274 }
12275 };
12276
12277 }
12278
12279 bool DataRecursiveIntBinOpEvaluator::
VisitBinOpLHSOnly(EvalResult & LHSResult,const BinaryOperator * E,bool & SuppressRHSDiags)12280 VisitBinOpLHSOnly(EvalResult &LHSResult, const BinaryOperator *E,
12281 bool &SuppressRHSDiags) {
12282 if (E->getOpcode() == BO_Comma) {
12283 // Ignore LHS but note if we could not evaluate it.
12284 if (LHSResult.Failed)
12285 return Info.noteSideEffect();
12286 return true;
12287 }
12288
12289 if (E->isLogicalOp()) {
12290 bool LHSAsBool;
12291 if (!LHSResult.Failed && HandleConversionToBool(LHSResult.Val, LHSAsBool)) {
12292 // We were able to evaluate the LHS, see if we can get away with not
12293 // evaluating the RHS: 0 && X -> 0, 1 || X -> 1
12294 if (LHSAsBool == (E->getOpcode() == BO_LOr)) {
12295 Success(LHSAsBool, E, LHSResult.Val);
12296 return false; // Ignore RHS
12297 }
12298 } else {
12299 LHSResult.Failed = true;
12300
12301 // Since we weren't able to evaluate the left hand side, it
12302 // might have had side effects.
12303 if (!Info.noteSideEffect())
12304 return false;
12305
12306 // We can't evaluate the LHS; however, sometimes the result
12307 // is determined by the RHS: X && 0 -> 0, X || 1 -> 1.
12308 // Don't ignore RHS and suppress diagnostics from this arm.
12309 SuppressRHSDiags = true;
12310 }
12311
12312 return true;
12313 }
12314
12315 assert(E->getLHS()->getType()->isIntegralOrEnumerationType() &&
12316 E->getRHS()->getType()->isIntegralOrEnumerationType());
12317
12318 if (LHSResult.Failed && !Info.noteFailure())
12319 return false; // Ignore RHS;
12320
12321 return true;
12322 }
12323
addOrSubLValueAsInteger(APValue & LVal,const APSInt & Index,bool IsSub)12324 static void addOrSubLValueAsInteger(APValue &LVal, const APSInt &Index,
12325 bool IsSub) {
12326 // Compute the new offset in the appropriate width, wrapping at 64 bits.
12327 // FIXME: When compiling for a 32-bit target, we should use 32-bit
12328 // offsets.
12329 assert(!LVal.hasLValuePath() && "have designator for integer lvalue");
12330 CharUnits &Offset = LVal.getLValueOffset();
12331 uint64_t Offset64 = Offset.getQuantity();
12332 uint64_t Index64 = Index.extOrTrunc(64).getZExtValue();
12333 Offset = CharUnits::fromQuantity(IsSub ? Offset64 - Index64
12334 : Offset64 + Index64);
12335 }
12336
12337 bool DataRecursiveIntBinOpEvaluator::
VisitBinOp(const EvalResult & LHSResult,const EvalResult & RHSResult,const BinaryOperator * E,APValue & Result)12338 VisitBinOp(const EvalResult &LHSResult, const EvalResult &RHSResult,
12339 const BinaryOperator *E, APValue &Result) {
12340 if (E->getOpcode() == BO_Comma) {
12341 if (RHSResult.Failed)
12342 return false;
12343 Result = RHSResult.Val;
12344 return true;
12345 }
12346
12347 if (E->isLogicalOp()) {
12348 bool lhsResult, rhsResult;
12349 bool LHSIsOK = HandleConversionToBool(LHSResult.Val, lhsResult);
12350 bool RHSIsOK = HandleConversionToBool(RHSResult.Val, rhsResult);
12351
12352 if (LHSIsOK) {
12353 if (RHSIsOK) {
12354 if (E->getOpcode() == BO_LOr)
12355 return Success(lhsResult || rhsResult, E, Result);
12356 else
12357 return Success(lhsResult && rhsResult, E, Result);
12358 }
12359 } else {
12360 if (RHSIsOK) {
12361 // We can't evaluate the LHS; however, sometimes the result
12362 // is determined by the RHS: X && 0 -> 0, X || 1 -> 1.
12363 if (rhsResult == (E->getOpcode() == BO_LOr))
12364 return Success(rhsResult, E, Result);
12365 }
12366 }
12367
12368 return false;
12369 }
12370
12371 assert(E->getLHS()->getType()->isIntegralOrEnumerationType() &&
12372 E->getRHS()->getType()->isIntegralOrEnumerationType());
12373
12374 if (LHSResult.Failed || RHSResult.Failed)
12375 return false;
12376
12377 const APValue &LHSVal = LHSResult.Val;
12378 const APValue &RHSVal = RHSResult.Val;
12379
12380 // Handle cases like (unsigned long)&a + 4.
12381 if (E->isAdditiveOp() && LHSVal.isLValue() && RHSVal.isInt()) {
12382 Result = LHSVal;
12383 addOrSubLValueAsInteger(Result, RHSVal.getInt(), E->getOpcode() == BO_Sub);
12384 return true;
12385 }
12386
12387 // Handle cases like 4 + (unsigned long)&a
12388 if (E->getOpcode() == BO_Add &&
12389 RHSVal.isLValue() && LHSVal.isInt()) {
12390 Result = RHSVal;
12391 addOrSubLValueAsInteger(Result, LHSVal.getInt(), /*IsSub*/false);
12392 return true;
12393 }
12394
12395 if (E->getOpcode() == BO_Sub && LHSVal.isLValue() && RHSVal.isLValue()) {
12396 // Handle (intptr_t)&&A - (intptr_t)&&B.
12397 if (!LHSVal.getLValueOffset().isZero() ||
12398 !RHSVal.getLValueOffset().isZero())
12399 return false;
12400 const Expr *LHSExpr = LHSVal.getLValueBase().dyn_cast<const Expr*>();
12401 const Expr *RHSExpr = RHSVal.getLValueBase().dyn_cast<const Expr*>();
12402 if (!LHSExpr || !RHSExpr)
12403 return false;
12404 const AddrLabelExpr *LHSAddrExpr = dyn_cast<AddrLabelExpr>(LHSExpr);
12405 const AddrLabelExpr *RHSAddrExpr = dyn_cast<AddrLabelExpr>(RHSExpr);
12406 if (!LHSAddrExpr || !RHSAddrExpr)
12407 return false;
12408 // Make sure both labels come from the same function.
12409 if (LHSAddrExpr->getLabel()->getDeclContext() !=
12410 RHSAddrExpr->getLabel()->getDeclContext())
12411 return false;
12412 Result = APValue(LHSAddrExpr, RHSAddrExpr);
12413 return true;
12414 }
12415
12416 // All the remaining cases expect both operands to be an integer
12417 if (!LHSVal.isInt() || !RHSVal.isInt())
12418 return Error(E);
12419
12420 // Set up the width and signedness manually, in case it can't be deduced
12421 // from the operation we're performing.
12422 // FIXME: Don't do this in the cases where we can deduce it.
12423 APSInt Value(Info.Ctx.getIntWidth(E->getType()),
12424 E->getType()->isUnsignedIntegerOrEnumerationType());
12425 if (!handleIntIntBinOp(Info, E, LHSVal.getInt(), E->getOpcode(),
12426 RHSVal.getInt(), Value))
12427 return false;
12428 return Success(Value, E, Result);
12429 }
12430
process(EvalResult & Result)12431 void DataRecursiveIntBinOpEvaluator::process(EvalResult &Result) {
12432 Job &job = Queue.back();
12433
12434 switch (job.Kind) {
12435 case Job::AnyExprKind: {
12436 if (const BinaryOperator *Bop = dyn_cast<BinaryOperator>(job.E)) {
12437 if (shouldEnqueue(Bop)) {
12438 job.Kind = Job::BinOpKind;
12439 enqueue(Bop->getLHS());
12440 return;
12441 }
12442 }
12443
12444 EvaluateExpr(job.E, Result);
12445 Queue.pop_back();
12446 return;
12447 }
12448
12449 case Job::BinOpKind: {
12450 const BinaryOperator *Bop = cast<BinaryOperator>(job.E);
12451 bool SuppressRHSDiags = false;
12452 if (!VisitBinOpLHSOnly(Result, Bop, SuppressRHSDiags)) {
12453 Queue.pop_back();
12454 return;
12455 }
12456 if (SuppressRHSDiags)
12457 job.startSpeculativeEval(Info);
12458 job.LHSResult.swap(Result);
12459 job.Kind = Job::BinOpVisitedLHSKind;
12460 enqueue(Bop->getRHS());
12461 return;
12462 }
12463
12464 case Job::BinOpVisitedLHSKind: {
12465 const BinaryOperator *Bop = cast<BinaryOperator>(job.E);
12466 EvalResult RHS;
12467 RHS.swap(Result);
12468 Result.Failed = !VisitBinOp(job.LHSResult, RHS, Bop, Result.Val);
12469 Queue.pop_back();
12470 return;
12471 }
12472 }
12473
12474 llvm_unreachable("Invalid Job::Kind!");
12475 }
12476
12477 namespace {
12478 enum class CmpResult {
12479 Unequal,
12480 Less,
12481 Equal,
12482 Greater,
12483 Unordered,
12484 };
12485 }
12486
12487 template <class SuccessCB, class AfterCB>
12488 static bool
EvaluateComparisonBinaryOperator(EvalInfo & Info,const BinaryOperator * E,SuccessCB && Success,AfterCB && DoAfter)12489 EvaluateComparisonBinaryOperator(EvalInfo &Info, const BinaryOperator *E,
12490 SuccessCB &&Success, AfterCB &&DoAfter) {
12491 assert(!E->isValueDependent());
12492 assert(E->isComparisonOp() && "expected comparison operator");
12493 assert((E->getOpcode() == BO_Cmp ||
12494 E->getType()->isIntegralOrEnumerationType()) &&
12495 "unsupported binary expression evaluation");
12496 auto Error = [&](const Expr *E) {
12497 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
12498 return false;
12499 };
12500
12501 bool IsRelational = E->isRelationalOp() || E->getOpcode() == BO_Cmp;
12502 bool IsEquality = E->isEqualityOp();
12503
12504 QualType LHSTy = E->getLHS()->getType();
12505 QualType RHSTy = E->getRHS()->getType();
12506
12507 if (LHSTy->isIntegralOrEnumerationType() &&
12508 RHSTy->isIntegralOrEnumerationType()) {
12509 APSInt LHS, RHS;
12510 bool LHSOK = EvaluateInteger(E->getLHS(), LHS, Info);
12511 if (!LHSOK && !Info.noteFailure())
12512 return false;
12513 if (!EvaluateInteger(E->getRHS(), RHS, Info) || !LHSOK)
12514 return false;
12515 if (LHS < RHS)
12516 return Success(CmpResult::Less, E);
12517 if (LHS > RHS)
12518 return Success(CmpResult::Greater, E);
12519 return Success(CmpResult::Equal, E);
12520 }
12521
12522 if (LHSTy->isFixedPointType() || RHSTy->isFixedPointType()) {
12523 APFixedPoint LHSFX(Info.Ctx.getFixedPointSemantics(LHSTy));
12524 APFixedPoint RHSFX(Info.Ctx.getFixedPointSemantics(RHSTy));
12525
12526 bool LHSOK = EvaluateFixedPointOrInteger(E->getLHS(), LHSFX, Info);
12527 if (!LHSOK && !Info.noteFailure())
12528 return false;
12529 if (!EvaluateFixedPointOrInteger(E->getRHS(), RHSFX, Info) || !LHSOK)
12530 return false;
12531 if (LHSFX < RHSFX)
12532 return Success(CmpResult::Less, E);
12533 if (LHSFX > RHSFX)
12534 return Success(CmpResult::Greater, E);
12535 return Success(CmpResult::Equal, E);
12536 }
12537
12538 if (LHSTy->isAnyComplexType() || RHSTy->isAnyComplexType()) {
12539 ComplexValue LHS, RHS;
12540 bool LHSOK;
12541 if (E->isAssignmentOp()) {
12542 LValue LV;
12543 EvaluateLValue(E->getLHS(), LV, Info);
12544 LHSOK = false;
12545 } else if (LHSTy->isRealFloatingType()) {
12546 LHSOK = EvaluateFloat(E->getLHS(), LHS.FloatReal, Info);
12547 if (LHSOK) {
12548 LHS.makeComplexFloat();
12549 LHS.FloatImag = APFloat(LHS.FloatReal.getSemantics());
12550 }
12551 } else {
12552 LHSOK = EvaluateComplex(E->getLHS(), LHS, Info);
12553 }
12554 if (!LHSOK && !Info.noteFailure())
12555 return false;
12556
12557 if (E->getRHS()->getType()->isRealFloatingType()) {
12558 if (!EvaluateFloat(E->getRHS(), RHS.FloatReal, Info) || !LHSOK)
12559 return false;
12560 RHS.makeComplexFloat();
12561 RHS.FloatImag = APFloat(RHS.FloatReal.getSemantics());
12562 } else if (!EvaluateComplex(E->getRHS(), RHS, Info) || !LHSOK)
12563 return false;
12564
12565 if (LHS.isComplexFloat()) {
12566 APFloat::cmpResult CR_r =
12567 LHS.getComplexFloatReal().compare(RHS.getComplexFloatReal());
12568 APFloat::cmpResult CR_i =
12569 LHS.getComplexFloatImag().compare(RHS.getComplexFloatImag());
12570 bool IsEqual = CR_r == APFloat::cmpEqual && CR_i == APFloat::cmpEqual;
12571 return Success(IsEqual ? CmpResult::Equal : CmpResult::Unequal, E);
12572 } else {
12573 assert(IsEquality && "invalid complex comparison");
12574 bool IsEqual = LHS.getComplexIntReal() == RHS.getComplexIntReal() &&
12575 LHS.getComplexIntImag() == RHS.getComplexIntImag();
12576 return Success(IsEqual ? CmpResult::Equal : CmpResult::Unequal, E);
12577 }
12578 }
12579
12580 if (LHSTy->isRealFloatingType() &&
12581 RHSTy->isRealFloatingType()) {
12582 APFloat RHS(0.0), LHS(0.0);
12583
12584 bool LHSOK = EvaluateFloat(E->getRHS(), RHS, Info);
12585 if (!LHSOK && !Info.noteFailure())
12586 return false;
12587
12588 if (!EvaluateFloat(E->getLHS(), LHS, Info) || !LHSOK)
12589 return false;
12590
12591 assert(E->isComparisonOp() && "Invalid binary operator!");
12592 llvm::APFloatBase::cmpResult APFloatCmpResult = LHS.compare(RHS);
12593 if (!Info.InConstantContext &&
12594 APFloatCmpResult == APFloat::cmpUnordered &&
12595 E->getFPFeaturesInEffect(Info.Ctx.getLangOpts()).isFPConstrained()) {
12596 // Note: Compares may raise invalid in some cases involving NaN or sNaN.
12597 Info.FFDiag(E, diag::note_constexpr_float_arithmetic_strict);
12598 return false;
12599 }
12600 auto GetCmpRes = [&]() {
12601 switch (APFloatCmpResult) {
12602 case APFloat::cmpEqual:
12603 return CmpResult::Equal;
12604 case APFloat::cmpLessThan:
12605 return CmpResult::Less;
12606 case APFloat::cmpGreaterThan:
12607 return CmpResult::Greater;
12608 case APFloat::cmpUnordered:
12609 return CmpResult::Unordered;
12610 }
12611 llvm_unreachable("Unrecognised APFloat::cmpResult enum");
12612 };
12613 return Success(GetCmpRes(), E);
12614 }
12615
12616 if (LHSTy->isPointerType() && RHSTy->isPointerType()) {
12617 LValue LHSValue, RHSValue;
12618
12619 bool LHSOK = EvaluatePointer(E->getLHS(), LHSValue, Info);
12620 if (!LHSOK && !Info.noteFailure())
12621 return false;
12622
12623 if (!EvaluatePointer(E->getRHS(), RHSValue, Info) || !LHSOK)
12624 return false;
12625
12626 // Reject differing bases from the normal codepath; we special-case
12627 // comparisons to null.
12628 if (!HasSameBase(LHSValue, RHSValue)) {
12629 // Inequalities and subtractions between unrelated pointers have
12630 // unspecified or undefined behavior.
12631 if (!IsEquality) {
12632 Info.FFDiag(E, diag::note_constexpr_pointer_comparison_unspecified);
12633 return false;
12634 }
12635 // A constant address may compare equal to the address of a symbol.
12636 // The one exception is that address of an object cannot compare equal
12637 // to a null pointer constant.
12638 if ((!LHSValue.Base && !LHSValue.Offset.isZero()) ||
12639 (!RHSValue.Base && !RHSValue.Offset.isZero()))
12640 return Error(E);
12641 // It's implementation-defined whether distinct literals will have
12642 // distinct addresses. In clang, the result of such a comparison is
12643 // unspecified, so it is not a constant expression. However, we do know
12644 // that the address of a literal will be non-null.
12645 if ((IsLiteralLValue(LHSValue) || IsLiteralLValue(RHSValue)) &&
12646 LHSValue.Base && RHSValue.Base)
12647 return Error(E);
12648 // We can't tell whether weak symbols will end up pointing to the same
12649 // object.
12650 if (IsWeakLValue(LHSValue) || IsWeakLValue(RHSValue))
12651 return Error(E);
12652 // We can't compare the address of the start of one object with the
12653 // past-the-end address of another object, per C++ DR1652.
12654 if ((LHSValue.Base && LHSValue.Offset.isZero() &&
12655 isOnePastTheEndOfCompleteObject(Info.Ctx, RHSValue)) ||
12656 (RHSValue.Base && RHSValue.Offset.isZero() &&
12657 isOnePastTheEndOfCompleteObject(Info.Ctx, LHSValue)))
12658 return Error(E);
12659 // We can't tell whether an object is at the same address as another
12660 // zero sized object.
12661 if ((RHSValue.Base && isZeroSized(LHSValue)) ||
12662 (LHSValue.Base && isZeroSized(RHSValue)))
12663 return Error(E);
12664 return Success(CmpResult::Unequal, E);
12665 }
12666
12667 const CharUnits &LHSOffset = LHSValue.getLValueOffset();
12668 const CharUnits &RHSOffset = RHSValue.getLValueOffset();
12669
12670 SubobjectDesignator &LHSDesignator = LHSValue.getLValueDesignator();
12671 SubobjectDesignator &RHSDesignator = RHSValue.getLValueDesignator();
12672
12673 // C++11 [expr.rel]p3:
12674 // Pointers to void (after pointer conversions) can be compared, with a
12675 // result defined as follows: If both pointers represent the same
12676 // address or are both the null pointer value, the result is true if the
12677 // operator is <= or >= and false otherwise; otherwise the result is
12678 // unspecified.
12679 // We interpret this as applying to pointers to *cv* void.
12680 if (LHSTy->isVoidPointerType() && LHSOffset != RHSOffset && IsRelational)
12681 Info.CCEDiag(E, diag::note_constexpr_void_comparison);
12682
12683 // C++11 [expr.rel]p2:
12684 // - If two pointers point to non-static data members of the same object,
12685 // or to subobjects or array elements fo such members, recursively, the
12686 // pointer to the later declared member compares greater provided the
12687 // two members have the same access control and provided their class is
12688 // not a union.
12689 // [...]
12690 // - Otherwise pointer comparisons are unspecified.
12691 if (!LHSDesignator.Invalid && !RHSDesignator.Invalid && IsRelational) {
12692 bool WasArrayIndex;
12693 unsigned Mismatch = FindDesignatorMismatch(
12694 getType(LHSValue.Base), LHSDesignator, RHSDesignator, WasArrayIndex);
12695 // At the point where the designators diverge, the comparison has a
12696 // specified value if:
12697 // - we are comparing array indices
12698 // - we are comparing fields of a union, or fields with the same access
12699 // Otherwise, the result is unspecified and thus the comparison is not a
12700 // constant expression.
12701 if (!WasArrayIndex && Mismatch < LHSDesignator.Entries.size() &&
12702 Mismatch < RHSDesignator.Entries.size()) {
12703 const FieldDecl *LF = getAsField(LHSDesignator.Entries[Mismatch]);
12704 const FieldDecl *RF = getAsField(RHSDesignator.Entries[Mismatch]);
12705 if (!LF && !RF)
12706 Info.CCEDiag(E, diag::note_constexpr_pointer_comparison_base_classes);
12707 else if (!LF)
12708 Info.CCEDiag(E, diag::note_constexpr_pointer_comparison_base_field)
12709 << getAsBaseClass(LHSDesignator.Entries[Mismatch])
12710 << RF->getParent() << RF;
12711 else if (!RF)
12712 Info.CCEDiag(E, diag::note_constexpr_pointer_comparison_base_field)
12713 << getAsBaseClass(RHSDesignator.Entries[Mismatch])
12714 << LF->getParent() << LF;
12715 else if (!LF->getParent()->isUnion() &&
12716 LF->getAccess() != RF->getAccess())
12717 Info.CCEDiag(E,
12718 diag::note_constexpr_pointer_comparison_differing_access)
12719 << LF << LF->getAccess() << RF << RF->getAccess()
12720 << LF->getParent();
12721 }
12722 }
12723
12724 // The comparison here must be unsigned, and performed with the same
12725 // width as the pointer.
12726 unsigned PtrSize = Info.Ctx.getTypeSize(LHSTy);
12727 uint64_t CompareLHS = LHSOffset.getQuantity();
12728 uint64_t CompareRHS = RHSOffset.getQuantity();
12729 assert(PtrSize <= 64 && "Unexpected pointer width");
12730 uint64_t Mask = ~0ULL >> (64 - PtrSize);
12731 CompareLHS &= Mask;
12732 CompareRHS &= Mask;
12733
12734 // If there is a base and this is a relational operator, we can only
12735 // compare pointers within the object in question; otherwise, the result
12736 // depends on where the object is located in memory.
12737 if (!LHSValue.Base.isNull() && IsRelational) {
12738 QualType BaseTy = getType(LHSValue.Base);
12739 if (BaseTy->isIncompleteType())
12740 return Error(E);
12741 CharUnits Size = Info.Ctx.getTypeSizeInChars(BaseTy);
12742 uint64_t OffsetLimit = Size.getQuantity();
12743 if (CompareLHS > OffsetLimit || CompareRHS > OffsetLimit)
12744 return Error(E);
12745 }
12746
12747 if (CompareLHS < CompareRHS)
12748 return Success(CmpResult::Less, E);
12749 if (CompareLHS > CompareRHS)
12750 return Success(CmpResult::Greater, E);
12751 return Success(CmpResult::Equal, E);
12752 }
12753
12754 if (LHSTy->isMemberPointerType()) {
12755 assert(IsEquality && "unexpected member pointer operation");
12756 assert(RHSTy->isMemberPointerType() && "invalid comparison");
12757
12758 MemberPtr LHSValue, RHSValue;
12759
12760 bool LHSOK = EvaluateMemberPointer(E->getLHS(), LHSValue, Info);
12761 if (!LHSOK && !Info.noteFailure())
12762 return false;
12763
12764 if (!EvaluateMemberPointer(E->getRHS(), RHSValue, Info) || !LHSOK)
12765 return false;
12766
12767 // C++11 [expr.eq]p2:
12768 // If both operands are null, they compare equal. Otherwise if only one is
12769 // null, they compare unequal.
12770 if (!LHSValue.getDecl() || !RHSValue.getDecl()) {
12771 bool Equal = !LHSValue.getDecl() && !RHSValue.getDecl();
12772 return Success(Equal ? CmpResult::Equal : CmpResult::Unequal, E);
12773 }
12774
12775 // Otherwise if either is a pointer to a virtual member function, the
12776 // result is unspecified.
12777 if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(LHSValue.getDecl()))
12778 if (MD->isVirtual())
12779 Info.CCEDiag(E, diag::note_constexpr_compare_virtual_mem_ptr) << MD;
12780 if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(RHSValue.getDecl()))
12781 if (MD->isVirtual())
12782 Info.CCEDiag(E, diag::note_constexpr_compare_virtual_mem_ptr) << MD;
12783
12784 // Otherwise they compare equal if and only if they would refer to the
12785 // same member of the same most derived object or the same subobject if
12786 // they were dereferenced with a hypothetical object of the associated
12787 // class type.
12788 bool Equal = LHSValue == RHSValue;
12789 return Success(Equal ? CmpResult::Equal : CmpResult::Unequal, E);
12790 }
12791
12792 if (LHSTy->isNullPtrType()) {
12793 assert(E->isComparisonOp() && "unexpected nullptr operation");
12794 assert(RHSTy->isNullPtrType() && "missing pointer conversion");
12795 // C++11 [expr.rel]p4, [expr.eq]p3: If two operands of type std::nullptr_t
12796 // are compared, the result is true of the operator is <=, >= or ==, and
12797 // false otherwise.
12798 return Success(CmpResult::Equal, E);
12799 }
12800
12801 return DoAfter();
12802 }
12803
VisitBinCmp(const BinaryOperator * E)12804 bool RecordExprEvaluator::VisitBinCmp(const BinaryOperator *E) {
12805 if (!CheckLiteralType(Info, E))
12806 return false;
12807
12808 auto OnSuccess = [&](CmpResult CR, const BinaryOperator *E) {
12809 ComparisonCategoryResult CCR;
12810 switch (CR) {
12811 case CmpResult::Unequal:
12812 llvm_unreachable("should never produce Unequal for three-way comparison");
12813 case CmpResult::Less:
12814 CCR = ComparisonCategoryResult::Less;
12815 break;
12816 case CmpResult::Equal:
12817 CCR = ComparisonCategoryResult::Equal;
12818 break;
12819 case CmpResult::Greater:
12820 CCR = ComparisonCategoryResult::Greater;
12821 break;
12822 case CmpResult::Unordered:
12823 CCR = ComparisonCategoryResult::Unordered;
12824 break;
12825 }
12826 // Evaluation succeeded. Lookup the information for the comparison category
12827 // type and fetch the VarDecl for the result.
12828 const ComparisonCategoryInfo &CmpInfo =
12829 Info.Ctx.CompCategories.getInfoForType(E->getType());
12830 const VarDecl *VD = CmpInfo.getValueInfo(CmpInfo.makeWeakResult(CCR))->VD;
12831 // Check and evaluate the result as a constant expression.
12832 LValue LV;
12833 LV.set(VD);
12834 if (!handleLValueToRValueConversion(Info, E, E->getType(), LV, Result))
12835 return false;
12836 return CheckConstantExpression(Info, E->getExprLoc(), E->getType(), Result,
12837 ConstantExprKind::Normal);
12838 };
12839 return EvaluateComparisonBinaryOperator(Info, E, OnSuccess, [&]() {
12840 return ExprEvaluatorBaseTy::VisitBinCmp(E);
12841 });
12842 }
12843
VisitBinaryOperator(const BinaryOperator * E)12844 bool IntExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
12845 // We don't support assignment in C. C++ assignments don't get here because
12846 // assignment is an lvalue in C++.
12847 if (E->isAssignmentOp()) {
12848 Error(E);
12849 if (!Info.noteFailure())
12850 return false;
12851 }
12852
12853 if (DataRecursiveIntBinOpEvaluator::shouldEnqueue(E))
12854 return DataRecursiveIntBinOpEvaluator(*this, Result).Traverse(E);
12855
12856 assert((!E->getLHS()->getType()->isIntegralOrEnumerationType() ||
12857 !E->getRHS()->getType()->isIntegralOrEnumerationType()) &&
12858 "DataRecursiveIntBinOpEvaluator should have handled integral types");
12859
12860 if (E->isComparisonOp()) {
12861 // Evaluate builtin binary comparisons by evaluating them as three-way
12862 // comparisons and then translating the result.
12863 auto OnSuccess = [&](CmpResult CR, const BinaryOperator *E) {
12864 assert((CR != CmpResult::Unequal || E->isEqualityOp()) &&
12865 "should only produce Unequal for equality comparisons");
12866 bool IsEqual = CR == CmpResult::Equal,
12867 IsLess = CR == CmpResult::Less,
12868 IsGreater = CR == CmpResult::Greater;
12869 auto Op = E->getOpcode();
12870 switch (Op) {
12871 default:
12872 llvm_unreachable("unsupported binary operator");
12873 case BO_EQ:
12874 case BO_NE:
12875 return Success(IsEqual == (Op == BO_EQ), E);
12876 case BO_LT:
12877 return Success(IsLess, E);
12878 case BO_GT:
12879 return Success(IsGreater, E);
12880 case BO_LE:
12881 return Success(IsEqual || IsLess, E);
12882 case BO_GE:
12883 return Success(IsEqual || IsGreater, E);
12884 }
12885 };
12886 return EvaluateComparisonBinaryOperator(Info, E, OnSuccess, [&]() {
12887 return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
12888 });
12889 }
12890
12891 QualType LHSTy = E->getLHS()->getType();
12892 QualType RHSTy = E->getRHS()->getType();
12893
12894 if (LHSTy->isPointerType() && RHSTy->isPointerType() &&
12895 E->getOpcode() == BO_Sub) {
12896 LValue LHSValue, RHSValue;
12897
12898 bool LHSOK = EvaluatePointer(E->getLHS(), LHSValue, Info);
12899 if (!LHSOK && !Info.noteFailure())
12900 return false;
12901
12902 if (!EvaluatePointer(E->getRHS(), RHSValue, Info) || !LHSOK)
12903 return false;
12904
12905 // Reject differing bases from the normal codepath; we special-case
12906 // comparisons to null.
12907 if (!HasSameBase(LHSValue, RHSValue)) {
12908 // Handle &&A - &&B.
12909 if (!LHSValue.Offset.isZero() || !RHSValue.Offset.isZero())
12910 return Error(E);
12911 const Expr *LHSExpr = LHSValue.Base.dyn_cast<const Expr *>();
12912 const Expr *RHSExpr = RHSValue.Base.dyn_cast<const Expr *>();
12913 if (!LHSExpr || !RHSExpr)
12914 return Error(E);
12915 const AddrLabelExpr *LHSAddrExpr = dyn_cast<AddrLabelExpr>(LHSExpr);
12916 const AddrLabelExpr *RHSAddrExpr = dyn_cast<AddrLabelExpr>(RHSExpr);
12917 if (!LHSAddrExpr || !RHSAddrExpr)
12918 return Error(E);
12919 // Make sure both labels come from the same function.
12920 if (LHSAddrExpr->getLabel()->getDeclContext() !=
12921 RHSAddrExpr->getLabel()->getDeclContext())
12922 return Error(E);
12923 return Success(APValue(LHSAddrExpr, RHSAddrExpr), E);
12924 }
12925 const CharUnits &LHSOffset = LHSValue.getLValueOffset();
12926 const CharUnits &RHSOffset = RHSValue.getLValueOffset();
12927
12928 SubobjectDesignator &LHSDesignator = LHSValue.getLValueDesignator();
12929 SubobjectDesignator &RHSDesignator = RHSValue.getLValueDesignator();
12930
12931 // C++11 [expr.add]p6:
12932 // Unless both pointers point to elements of the same array object, or
12933 // one past the last element of the array object, the behavior is
12934 // undefined.
12935 if (!LHSDesignator.Invalid && !RHSDesignator.Invalid &&
12936 !AreElementsOfSameArray(getType(LHSValue.Base), LHSDesignator,
12937 RHSDesignator))
12938 Info.CCEDiag(E, diag::note_constexpr_pointer_subtraction_not_same_array);
12939
12940 QualType Type = E->getLHS()->getType();
12941 QualType ElementType = Type->castAs<PointerType>()->getPointeeType();
12942
12943 CharUnits ElementSize;
12944 if (!HandleSizeof(Info, E->getExprLoc(), ElementType, ElementSize))
12945 return false;
12946
12947 // As an extension, a type may have zero size (empty struct or union in
12948 // C, array of zero length). Pointer subtraction in such cases has
12949 // undefined behavior, so is not constant.
12950 if (ElementSize.isZero()) {
12951 Info.FFDiag(E, diag::note_constexpr_pointer_subtraction_zero_size)
12952 << ElementType;
12953 return false;
12954 }
12955
12956 // FIXME: LLVM and GCC both compute LHSOffset - RHSOffset at runtime,
12957 // and produce incorrect results when it overflows. Such behavior
12958 // appears to be non-conforming, but is common, so perhaps we should
12959 // assume the standard intended for such cases to be undefined behavior
12960 // and check for them.
12961
12962 // Compute (LHSOffset - RHSOffset) / Size carefully, checking for
12963 // overflow in the final conversion to ptrdiff_t.
12964 APSInt LHS(llvm::APInt(65, (int64_t)LHSOffset.getQuantity(), true), false);
12965 APSInt RHS(llvm::APInt(65, (int64_t)RHSOffset.getQuantity(), true), false);
12966 APSInt ElemSize(llvm::APInt(65, (int64_t)ElementSize.getQuantity(), true),
12967 false);
12968 APSInt TrueResult = (LHS - RHS) / ElemSize;
12969 APSInt Result = TrueResult.trunc(Info.Ctx.getIntWidth(E->getType()));
12970
12971 if (Result.extend(65) != TrueResult &&
12972 !HandleOverflow(Info, E, TrueResult, E->getType()))
12973 return false;
12974 return Success(Result, E);
12975 }
12976
12977 return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
12978 }
12979
12980 /// VisitUnaryExprOrTypeTraitExpr - Evaluate a sizeof, alignof or vec_step with
12981 /// a result as the expression's type.
VisitUnaryExprOrTypeTraitExpr(const UnaryExprOrTypeTraitExpr * E)12982 bool IntExprEvaluator::VisitUnaryExprOrTypeTraitExpr(
12983 const UnaryExprOrTypeTraitExpr *E) {
12984 switch(E->getKind()) {
12985 case UETT_PreferredAlignOf:
12986 case UETT_AlignOf: {
12987 if (E->isArgumentType())
12988 return Success(GetAlignOfType(Info, E->getArgumentType(), E->getKind()),
12989 E);
12990 else
12991 return Success(GetAlignOfExpr(Info, E->getArgumentExpr(), E->getKind()),
12992 E);
12993 }
12994
12995 case UETT_VecStep: {
12996 QualType Ty = E->getTypeOfArgument();
12997
12998 if (Ty->isVectorType()) {
12999 unsigned n = Ty->castAs<VectorType>()->getNumElements();
13000
13001 // The vec_step built-in functions that take a 3-component
13002 // vector return 4. (OpenCL 1.1 spec 6.11.12)
13003 if (n == 3)
13004 n = 4;
13005
13006 return Success(n, E);
13007 } else
13008 return Success(1, E);
13009 }
13010
13011 case UETT_SizeOf: {
13012 QualType SrcTy = E->getTypeOfArgument();
13013 // C++ [expr.sizeof]p2: "When applied to a reference or a reference type,
13014 // the result is the size of the referenced type."
13015 if (const ReferenceType *Ref = SrcTy->getAs<ReferenceType>())
13016 SrcTy = Ref->getPointeeType();
13017
13018 CharUnits Sizeof;
13019 if (!HandleSizeof(Info, E->getExprLoc(), SrcTy, Sizeof))
13020 return false;
13021 return Success(Sizeof, E);
13022 }
13023 case UETT_OpenMPRequiredSimdAlign:
13024 assert(E->isArgumentType());
13025 return Success(
13026 Info.Ctx.toCharUnitsFromBits(
13027 Info.Ctx.getOpenMPDefaultSimdAlign(E->getArgumentType()))
13028 .getQuantity(),
13029 E);
13030 }
13031
13032 llvm_unreachable("unknown expr/type trait");
13033 }
13034
VisitOffsetOfExpr(const OffsetOfExpr * OOE)13035 bool IntExprEvaluator::VisitOffsetOfExpr(const OffsetOfExpr *OOE) {
13036 CharUnits Result;
13037 unsigned n = OOE->getNumComponents();
13038 if (n == 0)
13039 return Error(OOE);
13040 QualType CurrentType = OOE->getTypeSourceInfo()->getType();
13041 for (unsigned i = 0; i != n; ++i) {
13042 OffsetOfNode ON = OOE->getComponent(i);
13043 switch (ON.getKind()) {
13044 case OffsetOfNode::Array: {
13045 const Expr *Idx = OOE->getIndexExpr(ON.getArrayExprIndex());
13046 APSInt IdxResult;
13047 if (!EvaluateInteger(Idx, IdxResult, Info))
13048 return false;
13049 const ArrayType *AT = Info.Ctx.getAsArrayType(CurrentType);
13050 if (!AT)
13051 return Error(OOE);
13052 CurrentType = AT->getElementType();
13053 CharUnits ElementSize = Info.Ctx.getTypeSizeInChars(CurrentType);
13054 Result += IdxResult.getSExtValue() * ElementSize;
13055 break;
13056 }
13057
13058 case OffsetOfNode::Field: {
13059 FieldDecl *MemberDecl = ON.getField();
13060 const RecordType *RT = CurrentType->getAs<RecordType>();
13061 if (!RT)
13062 return Error(OOE);
13063 RecordDecl *RD = RT->getDecl();
13064 if (RD->isInvalidDecl()) return false;
13065 const ASTRecordLayout &RL = Info.Ctx.getASTRecordLayout(RD);
13066 unsigned i = MemberDecl->getFieldIndex();
13067 assert(i < RL.getFieldCount() && "offsetof field in wrong type");
13068 Result += Info.Ctx.toCharUnitsFromBits(RL.getFieldOffset(i));
13069 CurrentType = MemberDecl->getType().getNonReferenceType();
13070 break;
13071 }
13072
13073 case OffsetOfNode::Identifier:
13074 llvm_unreachable("dependent __builtin_offsetof");
13075
13076 case OffsetOfNode::Base: {
13077 CXXBaseSpecifier *BaseSpec = ON.getBase();
13078 if (BaseSpec->isVirtual())
13079 return Error(OOE);
13080
13081 // Find the layout of the class whose base we are looking into.
13082 const RecordType *RT = CurrentType->getAs<RecordType>();
13083 if (!RT)
13084 return Error(OOE);
13085 RecordDecl *RD = RT->getDecl();
13086 if (RD->isInvalidDecl()) return false;
13087 const ASTRecordLayout &RL = Info.Ctx.getASTRecordLayout(RD);
13088
13089 // Find the base class itself.
13090 CurrentType = BaseSpec->getType();
13091 const RecordType *BaseRT = CurrentType->getAs<RecordType>();
13092 if (!BaseRT)
13093 return Error(OOE);
13094
13095 // Add the offset to the base.
13096 Result += RL.getBaseClassOffset(cast<CXXRecordDecl>(BaseRT->getDecl()));
13097 break;
13098 }
13099 }
13100 }
13101 return Success(Result, OOE);
13102 }
13103
VisitUnaryOperator(const UnaryOperator * E)13104 bool IntExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) {
13105 switch (E->getOpcode()) {
13106 default:
13107 // Address, indirect, pre/post inc/dec, etc are not valid constant exprs.
13108 // See C99 6.6p3.
13109 return Error(E);
13110 case UO_Extension:
13111 // FIXME: Should extension allow i-c-e extension expressions in its scope?
13112 // If so, we could clear the diagnostic ID.
13113 return Visit(E->getSubExpr());
13114 case UO_Plus:
13115 // The result is just the value.
13116 return Visit(E->getSubExpr());
13117 case UO_Minus: {
13118 if (!Visit(E->getSubExpr()))
13119 return false;
13120 if (!Result.isInt()) return Error(E);
13121 const APSInt &Value = Result.getInt();
13122 if (Value.isSigned() && Value.isMinSignedValue() && E->canOverflow() &&
13123 !HandleOverflow(Info, E, -Value.extend(Value.getBitWidth() + 1),
13124 E->getType()))
13125 return false;
13126 return Success(-Value, E);
13127 }
13128 case UO_Not: {
13129 if (!Visit(E->getSubExpr()))
13130 return false;
13131 if (!Result.isInt()) return Error(E);
13132 return Success(~Result.getInt(), E);
13133 }
13134 case UO_LNot: {
13135 bool bres;
13136 if (!EvaluateAsBooleanCondition(E->getSubExpr(), bres, Info))
13137 return false;
13138 return Success(!bres, E);
13139 }
13140 }
13141 }
13142
13143 /// HandleCast - This is used to evaluate implicit or explicit casts where the
13144 /// result type is integer.
VisitCastExpr(const CastExpr * E)13145 bool IntExprEvaluator::VisitCastExpr(const CastExpr *E) {
13146 const Expr *SubExpr = E->getSubExpr();
13147 QualType DestType = E->getType();
13148 QualType SrcType = SubExpr->getType();
13149
13150 switch (E->getCastKind()) {
13151 case CK_BaseToDerived:
13152 case CK_DerivedToBase:
13153 case CK_UncheckedDerivedToBase:
13154 case CK_Dynamic:
13155 case CK_ToUnion:
13156 case CK_ArrayToPointerDecay:
13157 case CK_FunctionToPointerDecay:
13158 case CK_NullToPointer:
13159 case CK_NullToMemberPointer:
13160 case CK_BaseToDerivedMemberPointer:
13161 case CK_DerivedToBaseMemberPointer:
13162 case CK_ReinterpretMemberPointer:
13163 case CK_ConstructorConversion:
13164 case CK_IntegralToPointer:
13165 case CK_ToVoid:
13166 case CK_VectorSplat:
13167 case CK_IntegralToFloating:
13168 case CK_FloatingCast:
13169 case CK_CPointerToObjCPointerCast:
13170 case CK_BlockPointerToObjCPointerCast:
13171 case CK_AnyPointerToBlockPointerCast:
13172 case CK_ObjCObjectLValueCast:
13173 case CK_FloatingRealToComplex:
13174 case CK_FloatingComplexToReal:
13175 case CK_FloatingComplexCast:
13176 case CK_FloatingComplexToIntegralComplex:
13177 case CK_IntegralRealToComplex:
13178 case CK_IntegralComplexCast:
13179 case CK_IntegralComplexToFloatingComplex:
13180 case CK_BuiltinFnToFnPtr:
13181 case CK_ZeroToOCLOpaqueType:
13182 case CK_NonAtomicToAtomic:
13183 case CK_AddressSpaceConversion:
13184 case CK_IntToOCLSampler:
13185 case CK_FloatingToFixedPoint:
13186 case CK_FixedPointToFloating:
13187 case CK_FixedPointCast:
13188 case CK_IntegralToFixedPoint:
13189 case CK_MatrixCast:
13190 llvm_unreachable("invalid cast kind for integral value");
13191
13192 case CK_BitCast:
13193 case CK_Dependent:
13194 case CK_LValueBitCast:
13195 case CK_ARCProduceObject:
13196 case CK_ARCConsumeObject:
13197 case CK_ARCReclaimReturnedObject:
13198 case CK_ARCExtendBlockObject:
13199 case CK_CopyAndAutoreleaseBlockObject:
13200 return Error(E);
13201
13202 case CK_UserDefinedConversion:
13203 case CK_LValueToRValue:
13204 case CK_AtomicToNonAtomic:
13205 case CK_NoOp:
13206 case CK_LValueToRValueBitCast:
13207 return ExprEvaluatorBaseTy::VisitCastExpr(E);
13208
13209 case CK_MemberPointerToBoolean:
13210 case CK_PointerToBoolean:
13211 case CK_IntegralToBoolean:
13212 case CK_FloatingToBoolean:
13213 case CK_BooleanToSignedIntegral:
13214 case CK_FloatingComplexToBoolean:
13215 case CK_IntegralComplexToBoolean: {
13216 bool BoolResult;
13217 if (!EvaluateAsBooleanCondition(SubExpr, BoolResult, Info))
13218 return false;
13219 uint64_t IntResult = BoolResult;
13220 if (BoolResult && E->getCastKind() == CK_BooleanToSignedIntegral)
13221 IntResult = (uint64_t)-1;
13222 return Success(IntResult, E);
13223 }
13224
13225 case CK_FixedPointToIntegral: {
13226 APFixedPoint Src(Info.Ctx.getFixedPointSemantics(SrcType));
13227 if (!EvaluateFixedPoint(SubExpr, Src, Info))
13228 return false;
13229 bool Overflowed;
13230 llvm::APSInt Result = Src.convertToInt(
13231 Info.Ctx.getIntWidth(DestType),
13232 DestType->isSignedIntegerOrEnumerationType(), &Overflowed);
13233 if (Overflowed && !HandleOverflow(Info, E, Result, DestType))
13234 return false;
13235 return Success(Result, E);
13236 }
13237
13238 case CK_FixedPointToBoolean: {
13239 // Unsigned padding does not affect this.
13240 APValue Val;
13241 if (!Evaluate(Val, Info, SubExpr))
13242 return false;
13243 return Success(Val.getFixedPoint().getBoolValue(), E);
13244 }
13245
13246 case CK_IntegralCast: {
13247 if (!Visit(SubExpr))
13248 return false;
13249
13250 if (!Result.isInt()) {
13251 // Allow casts of address-of-label differences if they are no-ops
13252 // or narrowing. (The narrowing case isn't actually guaranteed to
13253 // be constant-evaluatable except in some narrow cases which are hard
13254 // to detect here. We let it through on the assumption the user knows
13255 // what they are doing.)
13256 if (Result.isAddrLabelDiff())
13257 return Info.Ctx.getTypeSize(DestType) <= Info.Ctx.getTypeSize(SrcType);
13258 // Only allow casts of lvalues if they are lossless.
13259 return Info.Ctx.getTypeSize(DestType) == Info.Ctx.getTypeSize(SrcType);
13260 }
13261
13262 return Success(HandleIntToIntCast(Info, E, DestType, SrcType,
13263 Result.getInt()), E);
13264 }
13265
13266 case CK_PointerToIntegral: {
13267 CCEDiag(E, diag::note_constexpr_invalid_cast) << 2;
13268
13269 LValue LV;
13270 if (!EvaluatePointer(SubExpr, LV, Info))
13271 return false;
13272
13273 if (LV.getLValueBase()) {
13274 // Only allow based lvalue casts if they are lossless.
13275 // FIXME: Allow a larger integer size than the pointer size, and allow
13276 // narrowing back down to pointer width in subsequent integral casts.
13277 // FIXME: Check integer type's active bits, not its type size.
13278 if (Info.Ctx.getTypeSize(DestType) != Info.Ctx.getTypeSize(SrcType))
13279 return Error(E);
13280
13281 LV.Designator.setInvalid();
13282 LV.moveInto(Result);
13283 return true;
13284 }
13285
13286 APSInt AsInt;
13287 APValue V;
13288 LV.moveInto(V);
13289 if (!V.toIntegralConstant(AsInt, SrcType, Info.Ctx))
13290 llvm_unreachable("Can't cast this!");
13291
13292 return Success(HandleIntToIntCast(Info, E, DestType, SrcType, AsInt), E);
13293 }
13294
13295 case CK_IntegralComplexToReal: {
13296 ComplexValue C;
13297 if (!EvaluateComplex(SubExpr, C, Info))
13298 return false;
13299 return Success(C.getComplexIntReal(), E);
13300 }
13301
13302 case CK_FloatingToIntegral: {
13303 APFloat F(0.0);
13304 if (!EvaluateFloat(SubExpr, F, Info))
13305 return false;
13306
13307 APSInt Value;
13308 if (!HandleFloatToIntCast(Info, E, SrcType, F, DestType, Value))
13309 return false;
13310 return Success(Value, E);
13311 }
13312 }
13313
13314 llvm_unreachable("unknown cast resulting in integral value");
13315 }
13316
VisitUnaryReal(const UnaryOperator * E)13317 bool IntExprEvaluator::VisitUnaryReal(const UnaryOperator *E) {
13318 if (E->getSubExpr()->getType()->isAnyComplexType()) {
13319 ComplexValue LV;
13320 if (!EvaluateComplex(E->getSubExpr(), LV, Info))
13321 return false;
13322 if (!LV.isComplexInt())
13323 return Error(E);
13324 return Success(LV.getComplexIntReal(), E);
13325 }
13326
13327 return Visit(E->getSubExpr());
13328 }
13329
VisitUnaryImag(const UnaryOperator * E)13330 bool IntExprEvaluator::VisitUnaryImag(const UnaryOperator *E) {
13331 if (E->getSubExpr()->getType()->isComplexIntegerType()) {
13332 ComplexValue LV;
13333 if (!EvaluateComplex(E->getSubExpr(), LV, Info))
13334 return false;
13335 if (!LV.isComplexInt())
13336 return Error(E);
13337 return Success(LV.getComplexIntImag(), E);
13338 }
13339
13340 VisitIgnoredValue(E->getSubExpr());
13341 return Success(0, E);
13342 }
13343
VisitSizeOfPackExpr(const SizeOfPackExpr * E)13344 bool IntExprEvaluator::VisitSizeOfPackExpr(const SizeOfPackExpr *E) {
13345 return Success(E->getPackLength(), E);
13346 }
13347
VisitCXXNoexceptExpr(const CXXNoexceptExpr * E)13348 bool IntExprEvaluator::VisitCXXNoexceptExpr(const CXXNoexceptExpr *E) {
13349 return Success(E->getValue(), E);
13350 }
13351
VisitConceptSpecializationExpr(const ConceptSpecializationExpr * E)13352 bool IntExprEvaluator::VisitConceptSpecializationExpr(
13353 const ConceptSpecializationExpr *E) {
13354 return Success(E->isSatisfied(), E);
13355 }
13356
VisitRequiresExpr(const RequiresExpr * E)13357 bool IntExprEvaluator::VisitRequiresExpr(const RequiresExpr *E) {
13358 return Success(E->isSatisfied(), E);
13359 }
13360
VisitUnaryOperator(const UnaryOperator * E)13361 bool FixedPointExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) {
13362 switch (E->getOpcode()) {
13363 default:
13364 // Invalid unary operators
13365 return Error(E);
13366 case UO_Plus:
13367 // The result is just the value.
13368 return Visit(E->getSubExpr());
13369 case UO_Minus: {
13370 if (!Visit(E->getSubExpr())) return false;
13371 if (!Result.isFixedPoint())
13372 return Error(E);
13373 bool Overflowed;
13374 APFixedPoint Negated = Result.getFixedPoint().negate(&Overflowed);
13375 if (Overflowed && !HandleOverflow(Info, E, Negated, E->getType()))
13376 return false;
13377 return Success(Negated, E);
13378 }
13379 case UO_LNot: {
13380 bool bres;
13381 if (!EvaluateAsBooleanCondition(E->getSubExpr(), bres, Info))
13382 return false;
13383 return Success(!bres, E);
13384 }
13385 }
13386 }
13387
VisitCastExpr(const CastExpr * E)13388 bool FixedPointExprEvaluator::VisitCastExpr(const CastExpr *E) {
13389 const Expr *SubExpr = E->getSubExpr();
13390 QualType DestType = E->getType();
13391 assert(DestType->isFixedPointType() &&
13392 "Expected destination type to be a fixed point type");
13393 auto DestFXSema = Info.Ctx.getFixedPointSemantics(DestType);
13394
13395 switch (E->getCastKind()) {
13396 case CK_FixedPointCast: {
13397 APFixedPoint Src(Info.Ctx.getFixedPointSemantics(SubExpr->getType()));
13398 if (!EvaluateFixedPoint(SubExpr, Src, Info))
13399 return false;
13400 bool Overflowed;
13401 APFixedPoint Result = Src.convert(DestFXSema, &Overflowed);
13402 if (Overflowed) {
13403 if (Info.checkingForUndefinedBehavior())
13404 Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
13405 diag::warn_fixedpoint_constant_overflow)
13406 << Result.toString() << E->getType();
13407 if (!HandleOverflow(Info, E, Result, E->getType()))
13408 return false;
13409 }
13410 return Success(Result, E);
13411 }
13412 case CK_IntegralToFixedPoint: {
13413 APSInt Src;
13414 if (!EvaluateInteger(SubExpr, Src, Info))
13415 return false;
13416
13417 bool Overflowed;
13418 APFixedPoint IntResult = APFixedPoint::getFromIntValue(
13419 Src, Info.Ctx.getFixedPointSemantics(DestType), &Overflowed);
13420
13421 if (Overflowed) {
13422 if (Info.checkingForUndefinedBehavior())
13423 Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
13424 diag::warn_fixedpoint_constant_overflow)
13425 << IntResult.toString() << E->getType();
13426 if (!HandleOverflow(Info, E, IntResult, E->getType()))
13427 return false;
13428 }
13429
13430 return Success(IntResult, E);
13431 }
13432 case CK_FloatingToFixedPoint: {
13433 APFloat Src(0.0);
13434 if (!EvaluateFloat(SubExpr, Src, Info))
13435 return false;
13436
13437 bool Overflowed;
13438 APFixedPoint Result = APFixedPoint::getFromFloatValue(
13439 Src, Info.Ctx.getFixedPointSemantics(DestType), &Overflowed);
13440
13441 if (Overflowed) {
13442 if (Info.checkingForUndefinedBehavior())
13443 Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
13444 diag::warn_fixedpoint_constant_overflow)
13445 << Result.toString() << E->getType();
13446 if (!HandleOverflow(Info, E, Result, E->getType()))
13447 return false;
13448 }
13449
13450 return Success(Result, E);
13451 }
13452 case CK_NoOp:
13453 case CK_LValueToRValue:
13454 return ExprEvaluatorBaseTy::VisitCastExpr(E);
13455 default:
13456 return Error(E);
13457 }
13458 }
13459
VisitBinaryOperator(const BinaryOperator * E)13460 bool FixedPointExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
13461 if (E->isPtrMemOp() || E->isAssignmentOp() || E->getOpcode() == BO_Comma)
13462 return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
13463
13464 const Expr *LHS = E->getLHS();
13465 const Expr *RHS = E->getRHS();
13466 FixedPointSemantics ResultFXSema =
13467 Info.Ctx.getFixedPointSemantics(E->getType());
13468
13469 APFixedPoint LHSFX(Info.Ctx.getFixedPointSemantics(LHS->getType()));
13470 if (!EvaluateFixedPointOrInteger(LHS, LHSFX, Info))
13471 return false;
13472 APFixedPoint RHSFX(Info.Ctx.getFixedPointSemantics(RHS->getType()));
13473 if (!EvaluateFixedPointOrInteger(RHS, RHSFX, Info))
13474 return false;
13475
13476 bool OpOverflow = false, ConversionOverflow = false;
13477 APFixedPoint Result(LHSFX.getSemantics());
13478 switch (E->getOpcode()) {
13479 case BO_Add: {
13480 Result = LHSFX.add(RHSFX, &OpOverflow)
13481 .convert(ResultFXSema, &ConversionOverflow);
13482 break;
13483 }
13484 case BO_Sub: {
13485 Result = LHSFX.sub(RHSFX, &OpOverflow)
13486 .convert(ResultFXSema, &ConversionOverflow);
13487 break;
13488 }
13489 case BO_Mul: {
13490 Result = LHSFX.mul(RHSFX, &OpOverflow)
13491 .convert(ResultFXSema, &ConversionOverflow);
13492 break;
13493 }
13494 case BO_Div: {
13495 if (RHSFX.getValue() == 0) {
13496 Info.FFDiag(E, diag::note_expr_divide_by_zero);
13497 return false;
13498 }
13499 Result = LHSFX.div(RHSFX, &OpOverflow)
13500 .convert(ResultFXSema, &ConversionOverflow);
13501 break;
13502 }
13503 case BO_Shl:
13504 case BO_Shr: {
13505 FixedPointSemantics LHSSema = LHSFX.getSemantics();
13506 llvm::APSInt RHSVal = RHSFX.getValue();
13507
13508 unsigned ShiftBW =
13509 LHSSema.getWidth() - (unsigned)LHSSema.hasUnsignedPadding();
13510 unsigned Amt = RHSVal.getLimitedValue(ShiftBW - 1);
13511 // Embedded-C 4.1.6.2.2:
13512 // The right operand must be nonnegative and less than the total number
13513 // of (nonpadding) bits of the fixed-point operand ...
13514 if (RHSVal.isNegative())
13515 Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHSVal;
13516 else if (Amt != RHSVal)
13517 Info.CCEDiag(E, diag::note_constexpr_large_shift)
13518 << RHSVal << E->getType() << ShiftBW;
13519
13520 if (E->getOpcode() == BO_Shl)
13521 Result = LHSFX.shl(Amt, &OpOverflow);
13522 else
13523 Result = LHSFX.shr(Amt, &OpOverflow);
13524 break;
13525 }
13526 default:
13527 return false;
13528 }
13529 if (OpOverflow || ConversionOverflow) {
13530 if (Info.checkingForUndefinedBehavior())
13531 Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
13532 diag::warn_fixedpoint_constant_overflow)
13533 << Result.toString() << E->getType();
13534 if (!HandleOverflow(Info, E, Result, E->getType()))
13535 return false;
13536 }
13537 return Success(Result, E);
13538 }
13539
13540 //===----------------------------------------------------------------------===//
13541 // Float Evaluation
13542 //===----------------------------------------------------------------------===//
13543
13544 namespace {
13545 class FloatExprEvaluator
13546 : public ExprEvaluatorBase<FloatExprEvaluator> {
13547 APFloat &Result;
13548 public:
FloatExprEvaluator(EvalInfo & info,APFloat & result)13549 FloatExprEvaluator(EvalInfo &info, APFloat &result)
13550 : ExprEvaluatorBaseTy(info), Result(result) {}
13551
Success(const APValue & V,const Expr * e)13552 bool Success(const APValue &V, const Expr *e) {
13553 Result = V.getFloat();
13554 return true;
13555 }
13556
ZeroInitialization(const Expr * E)13557 bool ZeroInitialization(const Expr *E) {
13558 Result = APFloat::getZero(Info.Ctx.getFloatTypeSemantics(E->getType()));
13559 return true;
13560 }
13561
13562 bool VisitCallExpr(const CallExpr *E);
13563
13564 bool VisitUnaryOperator(const UnaryOperator *E);
13565 bool VisitBinaryOperator(const BinaryOperator *E);
13566 bool VisitFloatingLiteral(const FloatingLiteral *E);
13567 bool VisitCastExpr(const CastExpr *E);
13568
13569 bool VisitUnaryReal(const UnaryOperator *E);
13570 bool VisitUnaryImag(const UnaryOperator *E);
13571
13572 // FIXME: Missing: array subscript of vector, member of vector
13573 };
13574 } // end anonymous namespace
13575
EvaluateFloat(const Expr * E,APFloat & Result,EvalInfo & Info)13576 static bool EvaluateFloat(const Expr* E, APFloat& Result, EvalInfo &Info) {
13577 assert(!E->isValueDependent());
13578 assert(E->isPRValue() && E->getType()->isRealFloatingType());
13579 return FloatExprEvaluator(Info, Result).Visit(E);
13580 }
13581
TryEvaluateBuiltinNaN(const ASTContext & Context,QualType ResultTy,const Expr * Arg,bool SNaN,llvm::APFloat & Result)13582 static bool TryEvaluateBuiltinNaN(const ASTContext &Context,
13583 QualType ResultTy,
13584 const Expr *Arg,
13585 bool SNaN,
13586 llvm::APFloat &Result) {
13587 const StringLiteral *S = dyn_cast<StringLiteral>(Arg->IgnoreParenCasts());
13588 if (!S) return false;
13589
13590 const llvm::fltSemantics &Sem = Context.getFloatTypeSemantics(ResultTy);
13591
13592 llvm::APInt fill;
13593
13594 // Treat empty strings as if they were zero.
13595 if (S->getString().empty())
13596 fill = llvm::APInt(32, 0);
13597 else if (S->getString().getAsInteger(0, fill))
13598 return false;
13599
13600 if (Context.getTargetInfo().isNan2008()) {
13601 if (SNaN)
13602 Result = llvm::APFloat::getSNaN(Sem, false, &fill);
13603 else
13604 Result = llvm::APFloat::getQNaN(Sem, false, &fill);
13605 } else {
13606 // Prior to IEEE 754-2008, architectures were allowed to choose whether
13607 // the first bit of their significand was set for qNaN or sNaN. MIPS chose
13608 // a different encoding to what became a standard in 2008, and for pre-
13609 // 2008 revisions, MIPS interpreted sNaN-2008 as qNan and qNaN-2008 as
13610 // sNaN. This is now known as "legacy NaN" encoding.
13611 if (SNaN)
13612 Result = llvm::APFloat::getQNaN(Sem, false, &fill);
13613 else
13614 Result = llvm::APFloat::getSNaN(Sem, false, &fill);
13615 }
13616
13617 return true;
13618 }
13619
VisitCallExpr(const CallExpr * E)13620 bool FloatExprEvaluator::VisitCallExpr(const CallExpr *E) {
13621 switch (E->getBuiltinCallee()) {
13622 default:
13623 return ExprEvaluatorBaseTy::VisitCallExpr(E);
13624
13625 case Builtin::BI__builtin_huge_val:
13626 case Builtin::BI__builtin_huge_valf:
13627 case Builtin::BI__builtin_huge_vall:
13628 case Builtin::BI__builtin_huge_valf128:
13629 case Builtin::BI__builtin_inf:
13630 case Builtin::BI__builtin_inff:
13631 case Builtin::BI__builtin_infl:
13632 case Builtin::BI__builtin_inff128: {
13633 const llvm::fltSemantics &Sem =
13634 Info.Ctx.getFloatTypeSemantics(E->getType());
13635 Result = llvm::APFloat::getInf(Sem);
13636 return true;
13637 }
13638
13639 case Builtin::BI__builtin_nans:
13640 case Builtin::BI__builtin_nansf:
13641 case Builtin::BI__builtin_nansl:
13642 case Builtin::BI__builtin_nansf128:
13643 if (!TryEvaluateBuiltinNaN(Info.Ctx, E->getType(), E->getArg(0),
13644 true, Result))
13645 return Error(E);
13646 return true;
13647
13648 case Builtin::BI__builtin_nan:
13649 case Builtin::BI__builtin_nanf:
13650 case Builtin::BI__builtin_nanl:
13651 case Builtin::BI__builtin_nanf128:
13652 // If this is __builtin_nan() turn this into a nan, otherwise we
13653 // can't constant fold it.
13654 if (!TryEvaluateBuiltinNaN(Info.Ctx, E->getType(), E->getArg(0),
13655 false, Result))
13656 return Error(E);
13657 return true;
13658
13659 case Builtin::BI__builtin_fabs:
13660 case Builtin::BI__builtin_fabsf:
13661 case Builtin::BI__builtin_fabsl:
13662 case Builtin::BI__builtin_fabsf128:
13663 // The C standard says "fabs raises no floating-point exceptions,
13664 // even if x is a signaling NaN. The returned value is independent of
13665 // the current rounding direction mode." Therefore constant folding can
13666 // proceed without regard to the floating point settings.
13667 // Reference, WG14 N2478 F.10.4.3
13668 if (!EvaluateFloat(E->getArg(0), Result, Info))
13669 return false;
13670
13671 if (Result.isNegative())
13672 Result.changeSign();
13673 return true;
13674
13675 case Builtin::BI__arithmetic_fence:
13676 return EvaluateFloat(E->getArg(0), Result, Info);
13677
13678 // FIXME: Builtin::BI__builtin_powi
13679 // FIXME: Builtin::BI__builtin_powif
13680 // FIXME: Builtin::BI__builtin_powil
13681
13682 case Builtin::BI__builtin_copysign:
13683 case Builtin::BI__builtin_copysignf:
13684 case Builtin::BI__builtin_copysignl:
13685 case Builtin::BI__builtin_copysignf128: {
13686 APFloat RHS(0.);
13687 if (!EvaluateFloat(E->getArg(0), Result, Info) ||
13688 !EvaluateFloat(E->getArg(1), RHS, Info))
13689 return false;
13690 Result.copySign(RHS);
13691 return true;
13692 }
13693 }
13694 }
13695
VisitUnaryReal(const UnaryOperator * E)13696 bool FloatExprEvaluator::VisitUnaryReal(const UnaryOperator *E) {
13697 if (E->getSubExpr()->getType()->isAnyComplexType()) {
13698 ComplexValue CV;
13699 if (!EvaluateComplex(E->getSubExpr(), CV, Info))
13700 return false;
13701 Result = CV.FloatReal;
13702 return true;
13703 }
13704
13705 return Visit(E->getSubExpr());
13706 }
13707
VisitUnaryImag(const UnaryOperator * E)13708 bool FloatExprEvaluator::VisitUnaryImag(const UnaryOperator *E) {
13709 if (E->getSubExpr()->getType()->isAnyComplexType()) {
13710 ComplexValue CV;
13711 if (!EvaluateComplex(E->getSubExpr(), CV, Info))
13712 return false;
13713 Result = CV.FloatImag;
13714 return true;
13715 }
13716
13717 VisitIgnoredValue(E->getSubExpr());
13718 const llvm::fltSemantics &Sem = Info.Ctx.getFloatTypeSemantics(E->getType());
13719 Result = llvm::APFloat::getZero(Sem);
13720 return true;
13721 }
13722
VisitUnaryOperator(const UnaryOperator * E)13723 bool FloatExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) {
13724 switch (E->getOpcode()) {
13725 default: return Error(E);
13726 case UO_Plus:
13727 return EvaluateFloat(E->getSubExpr(), Result, Info);
13728 case UO_Minus:
13729 // In C standard, WG14 N2478 F.3 p4
13730 // "the unary - raises no floating point exceptions,
13731 // even if the operand is signalling."
13732 if (!EvaluateFloat(E->getSubExpr(), Result, Info))
13733 return false;
13734 Result.changeSign();
13735 return true;
13736 }
13737 }
13738
VisitBinaryOperator(const BinaryOperator * E)13739 bool FloatExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
13740 if (E->isPtrMemOp() || E->isAssignmentOp() || E->getOpcode() == BO_Comma)
13741 return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
13742
13743 APFloat RHS(0.0);
13744 bool LHSOK = EvaluateFloat(E->getLHS(), Result, Info);
13745 if (!LHSOK && !Info.noteFailure())
13746 return false;
13747 return EvaluateFloat(E->getRHS(), RHS, Info) && LHSOK &&
13748 handleFloatFloatBinOp(Info, E, Result, E->getOpcode(), RHS);
13749 }
13750
VisitFloatingLiteral(const FloatingLiteral * E)13751 bool FloatExprEvaluator::VisitFloatingLiteral(const FloatingLiteral *E) {
13752 Result = E->getValue();
13753 return true;
13754 }
13755
VisitCastExpr(const CastExpr * E)13756 bool FloatExprEvaluator::VisitCastExpr(const CastExpr *E) {
13757 const Expr* SubExpr = E->getSubExpr();
13758
13759 switch (E->getCastKind()) {
13760 default:
13761 return ExprEvaluatorBaseTy::VisitCastExpr(E);
13762
13763 case CK_IntegralToFloating: {
13764 APSInt IntResult;
13765 const FPOptions FPO = E->getFPFeaturesInEffect(
13766 Info.Ctx.getLangOpts());
13767 return EvaluateInteger(SubExpr, IntResult, Info) &&
13768 HandleIntToFloatCast(Info, E, FPO, SubExpr->getType(),
13769 IntResult, E->getType(), Result);
13770 }
13771
13772 case CK_FixedPointToFloating: {
13773 APFixedPoint FixResult(Info.Ctx.getFixedPointSemantics(SubExpr->getType()));
13774 if (!EvaluateFixedPoint(SubExpr, FixResult, Info))
13775 return false;
13776 Result =
13777 FixResult.convertToFloat(Info.Ctx.getFloatTypeSemantics(E->getType()));
13778 return true;
13779 }
13780
13781 case CK_FloatingCast: {
13782 if (!Visit(SubExpr))
13783 return false;
13784 return HandleFloatToFloatCast(Info, E, SubExpr->getType(), E->getType(),
13785 Result);
13786 }
13787
13788 case CK_FloatingComplexToReal: {
13789 ComplexValue V;
13790 if (!EvaluateComplex(SubExpr, V, Info))
13791 return false;
13792 Result = V.getComplexFloatReal();
13793 return true;
13794 }
13795 }
13796 }
13797
13798 //===----------------------------------------------------------------------===//
13799 // Complex Evaluation (for float and integer)
13800 //===----------------------------------------------------------------------===//
13801
13802 namespace {
13803 class ComplexExprEvaluator
13804 : public ExprEvaluatorBase<ComplexExprEvaluator> {
13805 ComplexValue &Result;
13806
13807 public:
ComplexExprEvaluator(EvalInfo & info,ComplexValue & Result)13808 ComplexExprEvaluator(EvalInfo &info, ComplexValue &Result)
13809 : ExprEvaluatorBaseTy(info), Result(Result) {}
13810
Success(const APValue & V,const Expr * e)13811 bool Success(const APValue &V, const Expr *e) {
13812 Result.setFrom(V);
13813 return true;
13814 }
13815
13816 bool ZeroInitialization(const Expr *E);
13817
13818 //===--------------------------------------------------------------------===//
13819 // Visitor Methods
13820 //===--------------------------------------------------------------------===//
13821
13822 bool VisitImaginaryLiteral(const ImaginaryLiteral *E);
13823 bool VisitCastExpr(const CastExpr *E);
13824 bool VisitBinaryOperator(const BinaryOperator *E);
13825 bool VisitUnaryOperator(const UnaryOperator *E);
13826 bool VisitInitListExpr(const InitListExpr *E);
13827 bool VisitCallExpr(const CallExpr *E);
13828 };
13829 } // end anonymous namespace
13830
EvaluateComplex(const Expr * E,ComplexValue & Result,EvalInfo & Info)13831 static bool EvaluateComplex(const Expr *E, ComplexValue &Result,
13832 EvalInfo &Info) {
13833 assert(!E->isValueDependent());
13834 assert(E->isPRValue() && E->getType()->isAnyComplexType());
13835 return ComplexExprEvaluator(Info, Result).Visit(E);
13836 }
13837
ZeroInitialization(const Expr * E)13838 bool ComplexExprEvaluator::ZeroInitialization(const Expr *E) {
13839 QualType ElemTy = E->getType()->castAs<ComplexType>()->getElementType();
13840 if (ElemTy->isRealFloatingType()) {
13841 Result.makeComplexFloat();
13842 APFloat Zero = APFloat::getZero(Info.Ctx.getFloatTypeSemantics(ElemTy));
13843 Result.FloatReal = Zero;
13844 Result.FloatImag = Zero;
13845 } else {
13846 Result.makeComplexInt();
13847 APSInt Zero = Info.Ctx.MakeIntValue(0, ElemTy);
13848 Result.IntReal = Zero;
13849 Result.IntImag = Zero;
13850 }
13851 return true;
13852 }
13853
VisitImaginaryLiteral(const ImaginaryLiteral * E)13854 bool ComplexExprEvaluator::VisitImaginaryLiteral(const ImaginaryLiteral *E) {
13855 const Expr* SubExpr = E->getSubExpr();
13856
13857 if (SubExpr->getType()->isRealFloatingType()) {
13858 Result.makeComplexFloat();
13859 APFloat &Imag = Result.FloatImag;
13860 if (!EvaluateFloat(SubExpr, Imag, Info))
13861 return false;
13862
13863 Result.FloatReal = APFloat(Imag.getSemantics());
13864 return true;
13865 } else {
13866 assert(SubExpr->getType()->isIntegerType() &&
13867 "Unexpected imaginary literal.");
13868
13869 Result.makeComplexInt();
13870 APSInt &Imag = Result.IntImag;
13871 if (!EvaluateInteger(SubExpr, Imag, Info))
13872 return false;
13873
13874 Result.IntReal = APSInt(Imag.getBitWidth(), !Imag.isSigned());
13875 return true;
13876 }
13877 }
13878
VisitCastExpr(const CastExpr * E)13879 bool ComplexExprEvaluator::VisitCastExpr(const CastExpr *E) {
13880
13881 switch (E->getCastKind()) {
13882 case CK_BitCast:
13883 case CK_BaseToDerived:
13884 case CK_DerivedToBase:
13885 case CK_UncheckedDerivedToBase:
13886 case CK_Dynamic:
13887 case CK_ToUnion:
13888 case CK_ArrayToPointerDecay:
13889 case CK_FunctionToPointerDecay:
13890 case CK_NullToPointer:
13891 case CK_NullToMemberPointer:
13892 case CK_BaseToDerivedMemberPointer:
13893 case CK_DerivedToBaseMemberPointer:
13894 case CK_MemberPointerToBoolean:
13895 case CK_ReinterpretMemberPointer:
13896 case CK_ConstructorConversion:
13897 case CK_IntegralToPointer:
13898 case CK_PointerToIntegral:
13899 case CK_PointerToBoolean:
13900 case CK_ToVoid:
13901 case CK_VectorSplat:
13902 case CK_IntegralCast:
13903 case CK_BooleanToSignedIntegral:
13904 case CK_IntegralToBoolean:
13905 case CK_IntegralToFloating:
13906 case CK_FloatingToIntegral:
13907 case CK_FloatingToBoolean:
13908 case CK_FloatingCast:
13909 case CK_CPointerToObjCPointerCast:
13910 case CK_BlockPointerToObjCPointerCast:
13911 case CK_AnyPointerToBlockPointerCast:
13912 case CK_ObjCObjectLValueCast:
13913 case CK_FloatingComplexToReal:
13914 case CK_FloatingComplexToBoolean:
13915 case CK_IntegralComplexToReal:
13916 case CK_IntegralComplexToBoolean:
13917 case CK_ARCProduceObject:
13918 case CK_ARCConsumeObject:
13919 case CK_ARCReclaimReturnedObject:
13920 case CK_ARCExtendBlockObject:
13921 case CK_CopyAndAutoreleaseBlockObject:
13922 case CK_BuiltinFnToFnPtr:
13923 case CK_ZeroToOCLOpaqueType:
13924 case CK_NonAtomicToAtomic:
13925 case CK_AddressSpaceConversion:
13926 case CK_IntToOCLSampler:
13927 case CK_FloatingToFixedPoint:
13928 case CK_FixedPointToFloating:
13929 case CK_FixedPointCast:
13930 case CK_FixedPointToBoolean:
13931 case CK_FixedPointToIntegral:
13932 case CK_IntegralToFixedPoint:
13933 case CK_MatrixCast:
13934 llvm_unreachable("invalid cast kind for complex value");
13935
13936 case CK_LValueToRValue:
13937 case CK_AtomicToNonAtomic:
13938 case CK_NoOp:
13939 case CK_LValueToRValueBitCast:
13940 return ExprEvaluatorBaseTy::VisitCastExpr(E);
13941
13942 case CK_Dependent:
13943 case CK_LValueBitCast:
13944 case CK_UserDefinedConversion:
13945 return Error(E);
13946
13947 case CK_FloatingRealToComplex: {
13948 APFloat &Real = Result.FloatReal;
13949 if (!EvaluateFloat(E->getSubExpr(), Real, Info))
13950 return false;
13951
13952 Result.makeComplexFloat();
13953 Result.FloatImag = APFloat(Real.getSemantics());
13954 return true;
13955 }
13956
13957 case CK_FloatingComplexCast: {
13958 if (!Visit(E->getSubExpr()))
13959 return false;
13960
13961 QualType To = E->getType()->castAs<ComplexType>()->getElementType();
13962 QualType From
13963 = E->getSubExpr()->getType()->castAs<ComplexType>()->getElementType();
13964
13965 return HandleFloatToFloatCast(Info, E, From, To, Result.FloatReal) &&
13966 HandleFloatToFloatCast(Info, E, From, To, Result.FloatImag);
13967 }
13968
13969 case CK_FloatingComplexToIntegralComplex: {
13970 if (!Visit(E->getSubExpr()))
13971 return false;
13972
13973 QualType To = E->getType()->castAs<ComplexType>()->getElementType();
13974 QualType From
13975 = E->getSubExpr()->getType()->castAs<ComplexType>()->getElementType();
13976 Result.makeComplexInt();
13977 return HandleFloatToIntCast(Info, E, From, Result.FloatReal,
13978 To, Result.IntReal) &&
13979 HandleFloatToIntCast(Info, E, From, Result.FloatImag,
13980 To, Result.IntImag);
13981 }
13982
13983 case CK_IntegralRealToComplex: {
13984 APSInt &Real = Result.IntReal;
13985 if (!EvaluateInteger(E->getSubExpr(), Real, Info))
13986 return false;
13987
13988 Result.makeComplexInt();
13989 Result.IntImag = APSInt(Real.getBitWidth(), !Real.isSigned());
13990 return true;
13991 }
13992
13993 case CK_IntegralComplexCast: {
13994 if (!Visit(E->getSubExpr()))
13995 return false;
13996
13997 QualType To = E->getType()->castAs<ComplexType>()->getElementType();
13998 QualType From
13999 = E->getSubExpr()->getType()->castAs<ComplexType>()->getElementType();
14000
14001 Result.IntReal = HandleIntToIntCast(Info, E, To, From, Result.IntReal);
14002 Result.IntImag = HandleIntToIntCast(Info, E, To, From, Result.IntImag);
14003 return true;
14004 }
14005
14006 case CK_IntegralComplexToFloatingComplex: {
14007 if (!Visit(E->getSubExpr()))
14008 return false;
14009
14010 const FPOptions FPO = E->getFPFeaturesInEffect(
14011 Info.Ctx.getLangOpts());
14012 QualType To = E->getType()->castAs<ComplexType>()->getElementType();
14013 QualType From
14014 = E->getSubExpr()->getType()->castAs<ComplexType>()->getElementType();
14015 Result.makeComplexFloat();
14016 return HandleIntToFloatCast(Info, E, FPO, From, Result.IntReal,
14017 To, Result.FloatReal) &&
14018 HandleIntToFloatCast(Info, E, FPO, From, Result.IntImag,
14019 To, Result.FloatImag);
14020 }
14021 }
14022
14023 llvm_unreachable("unknown cast resulting in complex value");
14024 }
14025
VisitBinaryOperator(const BinaryOperator * E)14026 bool ComplexExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
14027 if (E->isPtrMemOp() || E->isAssignmentOp() || E->getOpcode() == BO_Comma)
14028 return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
14029
14030 // Track whether the LHS or RHS is real at the type system level. When this is
14031 // the case we can simplify our evaluation strategy.
14032 bool LHSReal = false, RHSReal = false;
14033
14034 bool LHSOK;
14035 if (E->getLHS()->getType()->isRealFloatingType()) {
14036 LHSReal = true;
14037 APFloat &Real = Result.FloatReal;
14038 LHSOK = EvaluateFloat(E->getLHS(), Real, Info);
14039 if (LHSOK) {
14040 Result.makeComplexFloat();
14041 Result.FloatImag = APFloat(Real.getSemantics());
14042 }
14043 } else {
14044 LHSOK = Visit(E->getLHS());
14045 }
14046 if (!LHSOK && !Info.noteFailure())
14047 return false;
14048
14049 ComplexValue RHS;
14050 if (E->getRHS()->getType()->isRealFloatingType()) {
14051 RHSReal = true;
14052 APFloat &Real = RHS.FloatReal;
14053 if (!EvaluateFloat(E->getRHS(), Real, Info) || !LHSOK)
14054 return false;
14055 RHS.makeComplexFloat();
14056 RHS.FloatImag = APFloat(Real.getSemantics());
14057 } else if (!EvaluateComplex(E->getRHS(), RHS, Info) || !LHSOK)
14058 return false;
14059
14060 assert(!(LHSReal && RHSReal) &&
14061 "Cannot have both operands of a complex operation be real.");
14062 switch (E->getOpcode()) {
14063 default: return Error(E);
14064 case BO_Add:
14065 if (Result.isComplexFloat()) {
14066 Result.getComplexFloatReal().add(RHS.getComplexFloatReal(),
14067 APFloat::rmNearestTiesToEven);
14068 if (LHSReal)
14069 Result.getComplexFloatImag() = RHS.getComplexFloatImag();
14070 else if (!RHSReal)
14071 Result.getComplexFloatImag().add(RHS.getComplexFloatImag(),
14072 APFloat::rmNearestTiesToEven);
14073 } else {
14074 Result.getComplexIntReal() += RHS.getComplexIntReal();
14075 Result.getComplexIntImag() += RHS.getComplexIntImag();
14076 }
14077 break;
14078 case BO_Sub:
14079 if (Result.isComplexFloat()) {
14080 Result.getComplexFloatReal().subtract(RHS.getComplexFloatReal(),
14081 APFloat::rmNearestTiesToEven);
14082 if (LHSReal) {
14083 Result.getComplexFloatImag() = RHS.getComplexFloatImag();
14084 Result.getComplexFloatImag().changeSign();
14085 } else if (!RHSReal) {
14086 Result.getComplexFloatImag().subtract(RHS.getComplexFloatImag(),
14087 APFloat::rmNearestTiesToEven);
14088 }
14089 } else {
14090 Result.getComplexIntReal() -= RHS.getComplexIntReal();
14091 Result.getComplexIntImag() -= RHS.getComplexIntImag();
14092 }
14093 break;
14094 case BO_Mul:
14095 if (Result.isComplexFloat()) {
14096 // This is an implementation of complex multiplication according to the
14097 // constraints laid out in C11 Annex G. The implementation uses the
14098 // following naming scheme:
14099 // (a + ib) * (c + id)
14100 ComplexValue LHS = Result;
14101 APFloat &A = LHS.getComplexFloatReal();
14102 APFloat &B = LHS.getComplexFloatImag();
14103 APFloat &C = RHS.getComplexFloatReal();
14104 APFloat &D = RHS.getComplexFloatImag();
14105 APFloat &ResR = Result.getComplexFloatReal();
14106 APFloat &ResI = Result.getComplexFloatImag();
14107 if (LHSReal) {
14108 assert(!RHSReal && "Cannot have two real operands for a complex op!");
14109 ResR = A * C;
14110 ResI = A * D;
14111 } else if (RHSReal) {
14112 ResR = C * A;
14113 ResI = C * B;
14114 } else {
14115 // In the fully general case, we need to handle NaNs and infinities
14116 // robustly.
14117 APFloat AC = A * C;
14118 APFloat BD = B * D;
14119 APFloat AD = A * D;
14120 APFloat BC = B * C;
14121 ResR = AC - BD;
14122 ResI = AD + BC;
14123 if (ResR.isNaN() && ResI.isNaN()) {
14124 bool Recalc = false;
14125 if (A.isInfinity() || B.isInfinity()) {
14126 A = APFloat::copySign(
14127 APFloat(A.getSemantics(), A.isInfinity() ? 1 : 0), A);
14128 B = APFloat::copySign(
14129 APFloat(B.getSemantics(), B.isInfinity() ? 1 : 0), B);
14130 if (C.isNaN())
14131 C = APFloat::copySign(APFloat(C.getSemantics()), C);
14132 if (D.isNaN())
14133 D = APFloat::copySign(APFloat(D.getSemantics()), D);
14134 Recalc = true;
14135 }
14136 if (C.isInfinity() || D.isInfinity()) {
14137 C = APFloat::copySign(
14138 APFloat(C.getSemantics(), C.isInfinity() ? 1 : 0), C);
14139 D = APFloat::copySign(
14140 APFloat(D.getSemantics(), D.isInfinity() ? 1 : 0), D);
14141 if (A.isNaN())
14142 A = APFloat::copySign(APFloat(A.getSemantics()), A);
14143 if (B.isNaN())
14144 B = APFloat::copySign(APFloat(B.getSemantics()), B);
14145 Recalc = true;
14146 }
14147 if (!Recalc && (AC.isInfinity() || BD.isInfinity() ||
14148 AD.isInfinity() || BC.isInfinity())) {
14149 if (A.isNaN())
14150 A = APFloat::copySign(APFloat(A.getSemantics()), A);
14151 if (B.isNaN())
14152 B = APFloat::copySign(APFloat(B.getSemantics()), B);
14153 if (C.isNaN())
14154 C = APFloat::copySign(APFloat(C.getSemantics()), C);
14155 if (D.isNaN())
14156 D = APFloat::copySign(APFloat(D.getSemantics()), D);
14157 Recalc = true;
14158 }
14159 if (Recalc) {
14160 ResR = APFloat::getInf(A.getSemantics()) * (A * C - B * D);
14161 ResI = APFloat::getInf(A.getSemantics()) * (A * D + B * C);
14162 }
14163 }
14164 }
14165 } else {
14166 ComplexValue LHS = Result;
14167 Result.getComplexIntReal() =
14168 (LHS.getComplexIntReal() * RHS.getComplexIntReal() -
14169 LHS.getComplexIntImag() * RHS.getComplexIntImag());
14170 Result.getComplexIntImag() =
14171 (LHS.getComplexIntReal() * RHS.getComplexIntImag() +
14172 LHS.getComplexIntImag() * RHS.getComplexIntReal());
14173 }
14174 break;
14175 case BO_Div:
14176 if (Result.isComplexFloat()) {
14177 // This is an implementation of complex division according to the
14178 // constraints laid out in C11 Annex G. The implementation uses the
14179 // following naming scheme:
14180 // (a + ib) / (c + id)
14181 ComplexValue LHS = Result;
14182 APFloat &A = LHS.getComplexFloatReal();
14183 APFloat &B = LHS.getComplexFloatImag();
14184 APFloat &C = RHS.getComplexFloatReal();
14185 APFloat &D = RHS.getComplexFloatImag();
14186 APFloat &ResR = Result.getComplexFloatReal();
14187 APFloat &ResI = Result.getComplexFloatImag();
14188 if (RHSReal) {
14189 ResR = A / C;
14190 ResI = B / C;
14191 } else {
14192 if (LHSReal) {
14193 // No real optimizations we can do here, stub out with zero.
14194 B = APFloat::getZero(A.getSemantics());
14195 }
14196 int DenomLogB = 0;
14197 APFloat MaxCD = maxnum(abs(C), abs(D));
14198 if (MaxCD.isFinite()) {
14199 DenomLogB = ilogb(MaxCD);
14200 C = scalbn(C, -DenomLogB, APFloat::rmNearestTiesToEven);
14201 D = scalbn(D, -DenomLogB, APFloat::rmNearestTiesToEven);
14202 }
14203 APFloat Denom = C * C + D * D;
14204 ResR = scalbn((A * C + B * D) / Denom, -DenomLogB,
14205 APFloat::rmNearestTiesToEven);
14206 ResI = scalbn((B * C - A * D) / Denom, -DenomLogB,
14207 APFloat::rmNearestTiesToEven);
14208 if (ResR.isNaN() && ResI.isNaN()) {
14209 if (Denom.isPosZero() && (!A.isNaN() || !B.isNaN())) {
14210 ResR = APFloat::getInf(ResR.getSemantics(), C.isNegative()) * A;
14211 ResI = APFloat::getInf(ResR.getSemantics(), C.isNegative()) * B;
14212 } else if ((A.isInfinity() || B.isInfinity()) && C.isFinite() &&
14213 D.isFinite()) {
14214 A = APFloat::copySign(
14215 APFloat(A.getSemantics(), A.isInfinity() ? 1 : 0), A);
14216 B = APFloat::copySign(
14217 APFloat(B.getSemantics(), B.isInfinity() ? 1 : 0), B);
14218 ResR = APFloat::getInf(ResR.getSemantics()) * (A * C + B * D);
14219 ResI = APFloat::getInf(ResI.getSemantics()) * (B * C - A * D);
14220 } else if (MaxCD.isInfinity() && A.isFinite() && B.isFinite()) {
14221 C = APFloat::copySign(
14222 APFloat(C.getSemantics(), C.isInfinity() ? 1 : 0), C);
14223 D = APFloat::copySign(
14224 APFloat(D.getSemantics(), D.isInfinity() ? 1 : 0), D);
14225 ResR = APFloat::getZero(ResR.getSemantics()) * (A * C + B * D);
14226 ResI = APFloat::getZero(ResI.getSemantics()) * (B * C - A * D);
14227 }
14228 }
14229 }
14230 } else {
14231 if (RHS.getComplexIntReal() == 0 && RHS.getComplexIntImag() == 0)
14232 return Error(E, diag::note_expr_divide_by_zero);
14233
14234 ComplexValue LHS = Result;
14235 APSInt Den = RHS.getComplexIntReal() * RHS.getComplexIntReal() +
14236 RHS.getComplexIntImag() * RHS.getComplexIntImag();
14237 Result.getComplexIntReal() =
14238 (LHS.getComplexIntReal() * RHS.getComplexIntReal() +
14239 LHS.getComplexIntImag() * RHS.getComplexIntImag()) / Den;
14240 Result.getComplexIntImag() =
14241 (LHS.getComplexIntImag() * RHS.getComplexIntReal() -
14242 LHS.getComplexIntReal() * RHS.getComplexIntImag()) / Den;
14243 }
14244 break;
14245 }
14246
14247 return true;
14248 }
14249
VisitUnaryOperator(const UnaryOperator * E)14250 bool ComplexExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) {
14251 // Get the operand value into 'Result'.
14252 if (!Visit(E->getSubExpr()))
14253 return false;
14254
14255 switch (E->getOpcode()) {
14256 default:
14257 return Error(E);
14258 case UO_Extension:
14259 return true;
14260 case UO_Plus:
14261 // The result is always just the subexpr.
14262 return true;
14263 case UO_Minus:
14264 if (Result.isComplexFloat()) {
14265 Result.getComplexFloatReal().changeSign();
14266 Result.getComplexFloatImag().changeSign();
14267 }
14268 else {
14269 Result.getComplexIntReal() = -Result.getComplexIntReal();
14270 Result.getComplexIntImag() = -Result.getComplexIntImag();
14271 }
14272 return true;
14273 case UO_Not:
14274 if (Result.isComplexFloat())
14275 Result.getComplexFloatImag().changeSign();
14276 else
14277 Result.getComplexIntImag() = -Result.getComplexIntImag();
14278 return true;
14279 }
14280 }
14281
VisitInitListExpr(const InitListExpr * E)14282 bool ComplexExprEvaluator::VisitInitListExpr(const InitListExpr *E) {
14283 if (E->getNumInits() == 2) {
14284 if (E->getType()->isComplexType()) {
14285 Result.makeComplexFloat();
14286 if (!EvaluateFloat(E->getInit(0), Result.FloatReal, Info))
14287 return false;
14288 if (!EvaluateFloat(E->getInit(1), Result.FloatImag, Info))
14289 return false;
14290 } else {
14291 Result.makeComplexInt();
14292 if (!EvaluateInteger(E->getInit(0), Result.IntReal, Info))
14293 return false;
14294 if (!EvaluateInteger(E->getInit(1), Result.IntImag, Info))
14295 return false;
14296 }
14297 return true;
14298 }
14299 return ExprEvaluatorBaseTy::VisitInitListExpr(E);
14300 }
14301
VisitCallExpr(const CallExpr * E)14302 bool ComplexExprEvaluator::VisitCallExpr(const CallExpr *E) {
14303 switch (E->getBuiltinCallee()) {
14304 case Builtin::BI__builtin_complex:
14305 Result.makeComplexFloat();
14306 if (!EvaluateFloat(E->getArg(0), Result.FloatReal, Info))
14307 return false;
14308 if (!EvaluateFloat(E->getArg(1), Result.FloatImag, Info))
14309 return false;
14310 return true;
14311
14312 default:
14313 break;
14314 }
14315
14316 return ExprEvaluatorBaseTy::VisitCallExpr(E);
14317 }
14318
14319 //===----------------------------------------------------------------------===//
14320 // Atomic expression evaluation, essentially just handling the NonAtomicToAtomic
14321 // implicit conversion.
14322 //===----------------------------------------------------------------------===//
14323
14324 namespace {
14325 class AtomicExprEvaluator :
14326 public ExprEvaluatorBase<AtomicExprEvaluator> {
14327 const LValue *This;
14328 APValue &Result;
14329 public:
AtomicExprEvaluator(EvalInfo & Info,const LValue * This,APValue & Result)14330 AtomicExprEvaluator(EvalInfo &Info, const LValue *This, APValue &Result)
14331 : ExprEvaluatorBaseTy(Info), This(This), Result(Result) {}
14332
Success(const APValue & V,const Expr * E)14333 bool Success(const APValue &V, const Expr *E) {
14334 Result = V;
14335 return true;
14336 }
14337
ZeroInitialization(const Expr * E)14338 bool ZeroInitialization(const Expr *E) {
14339 ImplicitValueInitExpr VIE(
14340 E->getType()->castAs<AtomicType>()->getValueType());
14341 // For atomic-qualified class (and array) types in C++, initialize the
14342 // _Atomic-wrapped subobject directly, in-place.
14343 return This ? EvaluateInPlace(Result, Info, *This, &VIE)
14344 : Evaluate(Result, Info, &VIE);
14345 }
14346
VisitCastExpr(const CastExpr * E)14347 bool VisitCastExpr(const CastExpr *E) {
14348 switch (E->getCastKind()) {
14349 default:
14350 return ExprEvaluatorBaseTy::VisitCastExpr(E);
14351 case CK_NonAtomicToAtomic:
14352 return This ? EvaluateInPlace(Result, Info, *This, E->getSubExpr())
14353 : Evaluate(Result, Info, E->getSubExpr());
14354 }
14355 }
14356 };
14357 } // end anonymous namespace
14358
EvaluateAtomic(const Expr * E,const LValue * This,APValue & Result,EvalInfo & Info)14359 static bool EvaluateAtomic(const Expr *E, const LValue *This, APValue &Result,
14360 EvalInfo &Info) {
14361 assert(!E->isValueDependent());
14362 assert(E->isPRValue() && E->getType()->isAtomicType());
14363 return AtomicExprEvaluator(Info, This, Result).Visit(E);
14364 }
14365
14366 //===----------------------------------------------------------------------===//
14367 // Void expression evaluation, primarily for a cast to void on the LHS of a
14368 // comma operator
14369 //===----------------------------------------------------------------------===//
14370
14371 namespace {
14372 class VoidExprEvaluator
14373 : public ExprEvaluatorBase<VoidExprEvaluator> {
14374 public:
VoidExprEvaluator(EvalInfo & Info)14375 VoidExprEvaluator(EvalInfo &Info) : ExprEvaluatorBaseTy(Info) {}
14376
Success(const APValue & V,const Expr * e)14377 bool Success(const APValue &V, const Expr *e) { return true; }
14378
ZeroInitialization(const Expr * E)14379 bool ZeroInitialization(const Expr *E) { return true; }
14380
VisitCastExpr(const CastExpr * E)14381 bool VisitCastExpr(const CastExpr *E) {
14382 switch (E->getCastKind()) {
14383 default:
14384 return ExprEvaluatorBaseTy::VisitCastExpr(E);
14385 case CK_ToVoid:
14386 VisitIgnoredValue(E->getSubExpr());
14387 return true;
14388 }
14389 }
14390
VisitCallExpr(const CallExpr * E)14391 bool VisitCallExpr(const CallExpr *E) {
14392 switch (E->getBuiltinCallee()) {
14393 case Builtin::BI__assume:
14394 case Builtin::BI__builtin_assume:
14395 // The argument is not evaluated!
14396 return true;
14397
14398 case Builtin::BI__builtin_operator_delete:
14399 return HandleOperatorDeleteCall(Info, E);
14400
14401 default:
14402 break;
14403 }
14404
14405 return ExprEvaluatorBaseTy::VisitCallExpr(E);
14406 }
14407
14408 bool VisitCXXDeleteExpr(const CXXDeleteExpr *E);
14409 };
14410 } // end anonymous namespace
14411
VisitCXXDeleteExpr(const CXXDeleteExpr * E)14412 bool VoidExprEvaluator::VisitCXXDeleteExpr(const CXXDeleteExpr *E) {
14413 // We cannot speculatively evaluate a delete expression.
14414 if (Info.SpeculativeEvaluationDepth)
14415 return false;
14416
14417 FunctionDecl *OperatorDelete = E->getOperatorDelete();
14418 if (!OperatorDelete->isReplaceableGlobalAllocationFunction()) {
14419 Info.FFDiag(E, diag::note_constexpr_new_non_replaceable)
14420 << isa<CXXMethodDecl>(OperatorDelete) << OperatorDelete;
14421 return false;
14422 }
14423
14424 const Expr *Arg = E->getArgument();
14425
14426 LValue Pointer;
14427 if (!EvaluatePointer(Arg, Pointer, Info))
14428 return false;
14429 if (Pointer.Designator.Invalid)
14430 return false;
14431
14432 // Deleting a null pointer has no effect.
14433 if (Pointer.isNullPointer()) {
14434 // This is the only case where we need to produce an extension warning:
14435 // the only other way we can succeed is if we find a dynamic allocation,
14436 // and we will have warned when we allocated it in that case.
14437 if (!Info.getLangOpts().CPlusPlus20)
14438 Info.CCEDiag(E, diag::note_constexpr_new);
14439 return true;
14440 }
14441
14442 Optional<DynAlloc *> Alloc = CheckDeleteKind(
14443 Info, E, Pointer, E->isArrayForm() ? DynAlloc::ArrayNew : DynAlloc::New);
14444 if (!Alloc)
14445 return false;
14446 QualType AllocType = Pointer.Base.getDynamicAllocType();
14447
14448 // For the non-array case, the designator must be empty if the static type
14449 // does not have a virtual destructor.
14450 if (!E->isArrayForm() && Pointer.Designator.Entries.size() != 0 &&
14451 !hasVirtualDestructor(Arg->getType()->getPointeeType())) {
14452 Info.FFDiag(E, diag::note_constexpr_delete_base_nonvirt_dtor)
14453 << Arg->getType()->getPointeeType() << AllocType;
14454 return false;
14455 }
14456
14457 // For a class type with a virtual destructor, the selected operator delete
14458 // is the one looked up when building the destructor.
14459 if (!E->isArrayForm() && !E->isGlobalDelete()) {
14460 const FunctionDecl *VirtualDelete = getVirtualOperatorDelete(AllocType);
14461 if (VirtualDelete &&
14462 !VirtualDelete->isReplaceableGlobalAllocationFunction()) {
14463 Info.FFDiag(E, diag::note_constexpr_new_non_replaceable)
14464 << isa<CXXMethodDecl>(VirtualDelete) << VirtualDelete;
14465 return false;
14466 }
14467 }
14468
14469 if (!HandleDestruction(Info, E->getExprLoc(), Pointer.getLValueBase(),
14470 (*Alloc)->Value, AllocType))
14471 return false;
14472
14473 if (!Info.HeapAllocs.erase(Pointer.Base.dyn_cast<DynamicAllocLValue>())) {
14474 // The element was already erased. This means the destructor call also
14475 // deleted the object.
14476 // FIXME: This probably results in undefined behavior before we get this
14477 // far, and should be diagnosed elsewhere first.
14478 Info.FFDiag(E, diag::note_constexpr_double_delete);
14479 return false;
14480 }
14481
14482 return true;
14483 }
14484
EvaluateVoid(const Expr * E,EvalInfo & Info)14485 static bool EvaluateVoid(const Expr *E, EvalInfo &Info) {
14486 assert(!E->isValueDependent());
14487 assert(E->isPRValue() && E->getType()->isVoidType());
14488 return VoidExprEvaluator(Info).Visit(E);
14489 }
14490
14491 //===----------------------------------------------------------------------===//
14492 // Top level Expr::EvaluateAsRValue method.
14493 //===----------------------------------------------------------------------===//
14494
Evaluate(APValue & Result,EvalInfo & Info,const Expr * E)14495 static bool Evaluate(APValue &Result, EvalInfo &Info, const Expr *E) {
14496 assert(!E->isValueDependent());
14497 // In C, function designators are not lvalues, but we evaluate them as if they
14498 // are.
14499 QualType T = E->getType();
14500 if (E->isGLValue() || T->isFunctionType()) {
14501 LValue LV;
14502 if (!EvaluateLValue(E, LV, Info))
14503 return false;
14504 LV.moveInto(Result);
14505 } else if (T->isVectorType()) {
14506 if (!EvaluateVector(E, Result, Info))
14507 return false;
14508 } else if (T->isIntegralOrEnumerationType()) {
14509 if (!IntExprEvaluator(Info, Result).Visit(E))
14510 return false;
14511 } else if (T->hasPointerRepresentation()) {
14512 LValue LV;
14513 if (!EvaluatePointer(E, LV, Info))
14514 return false;
14515 LV.moveInto(Result);
14516 } else if (T->isRealFloatingType()) {
14517 llvm::APFloat F(0.0);
14518 if (!EvaluateFloat(E, F, Info))
14519 return false;
14520 Result = APValue(F);
14521 } else if (T->isAnyComplexType()) {
14522 ComplexValue C;
14523 if (!EvaluateComplex(E, C, Info))
14524 return false;
14525 C.moveInto(Result);
14526 } else if (T->isFixedPointType()) {
14527 if (!FixedPointExprEvaluator(Info, Result).Visit(E)) return false;
14528 } else if (T->isMemberPointerType()) {
14529 MemberPtr P;
14530 if (!EvaluateMemberPointer(E, P, Info))
14531 return false;
14532 P.moveInto(Result);
14533 return true;
14534 } else if (T->isArrayType()) {
14535 LValue LV;
14536 APValue &Value =
14537 Info.CurrentCall->createTemporary(E, T, ScopeKind::FullExpression, LV);
14538 if (!EvaluateArray(E, LV, Value, Info))
14539 return false;
14540 Result = Value;
14541 } else if (T->isRecordType()) {
14542 LValue LV;
14543 APValue &Value =
14544 Info.CurrentCall->createTemporary(E, T, ScopeKind::FullExpression, LV);
14545 if (!EvaluateRecord(E, LV, Value, Info))
14546 return false;
14547 Result = Value;
14548 } else if (T->isVoidType()) {
14549 if (!Info.getLangOpts().CPlusPlus11)
14550 Info.CCEDiag(E, diag::note_constexpr_nonliteral)
14551 << E->getType();
14552 if (!EvaluateVoid(E, Info))
14553 return false;
14554 } else if (T->isAtomicType()) {
14555 QualType Unqual = T.getAtomicUnqualifiedType();
14556 if (Unqual->isArrayType() || Unqual->isRecordType()) {
14557 LValue LV;
14558 APValue &Value = Info.CurrentCall->createTemporary(
14559 E, Unqual, ScopeKind::FullExpression, LV);
14560 if (!EvaluateAtomic(E, &LV, Value, Info))
14561 return false;
14562 } else {
14563 if (!EvaluateAtomic(E, nullptr, Result, Info))
14564 return false;
14565 }
14566 } else if (Info.getLangOpts().CPlusPlus11) {
14567 Info.FFDiag(E, diag::note_constexpr_nonliteral) << E->getType();
14568 return false;
14569 } else {
14570 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
14571 return false;
14572 }
14573
14574 return true;
14575 }
14576
14577 /// EvaluateInPlace - Evaluate an expression in-place in an APValue. In some
14578 /// cases, the in-place evaluation is essential, since later initializers for
14579 /// an object can indirectly refer to subobjects which were initialized earlier.
EvaluateInPlace(APValue & Result,EvalInfo & Info,const LValue & This,const Expr * E,bool AllowNonLiteralTypes)14580 static bool EvaluateInPlace(APValue &Result, EvalInfo &Info, const LValue &This,
14581 const Expr *E, bool AllowNonLiteralTypes) {
14582 assert(!E->isValueDependent());
14583
14584 if (!AllowNonLiteralTypes && !CheckLiteralType(Info, E, &This))
14585 return false;
14586
14587 if (E->isPRValue()) {
14588 // Evaluate arrays and record types in-place, so that later initializers can
14589 // refer to earlier-initialized members of the object.
14590 QualType T = E->getType();
14591 if (T->isArrayType())
14592 return EvaluateArray(E, This, Result, Info);
14593 else if (T->isRecordType())
14594 return EvaluateRecord(E, This, Result, Info);
14595 else if (T->isAtomicType()) {
14596 QualType Unqual = T.getAtomicUnqualifiedType();
14597 if (Unqual->isArrayType() || Unqual->isRecordType())
14598 return EvaluateAtomic(E, &This, Result, Info);
14599 }
14600 }
14601
14602 // For any other type, in-place evaluation is unimportant.
14603 return Evaluate(Result, Info, E);
14604 }
14605
14606 /// EvaluateAsRValue - Try to evaluate this expression, performing an implicit
14607 /// lvalue-to-rvalue cast if it is an lvalue.
EvaluateAsRValue(EvalInfo & Info,const Expr * E,APValue & Result)14608 static bool EvaluateAsRValue(EvalInfo &Info, const Expr *E, APValue &Result) {
14609 assert(!E->isValueDependent());
14610 if (Info.EnableNewConstInterp) {
14611 if (!Info.Ctx.getInterpContext().evaluateAsRValue(Info, E, Result))
14612 return false;
14613 } else {
14614 if (E->getType().isNull())
14615 return false;
14616
14617 if (!CheckLiteralType(Info, E))
14618 return false;
14619
14620 if (!::Evaluate(Result, Info, E))
14621 return false;
14622
14623 if (E->isGLValue()) {
14624 LValue LV;
14625 LV.setFrom(Info.Ctx, Result);
14626 if (!handleLValueToRValueConversion(Info, E, E->getType(), LV, Result))
14627 return false;
14628 }
14629 }
14630
14631 // Check this core constant expression is a constant expression.
14632 return CheckConstantExpression(Info, E->getExprLoc(), E->getType(), Result,
14633 ConstantExprKind::Normal) &&
14634 CheckMemoryLeaks(Info);
14635 }
14636
FastEvaluateAsRValue(const Expr * Exp,Expr::EvalResult & Result,const ASTContext & Ctx,bool & IsConst)14637 static bool FastEvaluateAsRValue(const Expr *Exp, Expr::EvalResult &Result,
14638 const ASTContext &Ctx, bool &IsConst) {
14639 // Fast-path evaluations of integer literals, since we sometimes see files
14640 // containing vast quantities of these.
14641 if (const IntegerLiteral *L = dyn_cast<IntegerLiteral>(Exp)) {
14642 Result.Val = APValue(APSInt(L->getValue(),
14643 L->getType()->isUnsignedIntegerType()));
14644 IsConst = true;
14645 return true;
14646 }
14647
14648 // This case should be rare, but we need to check it before we check on
14649 // the type below.
14650 if (Exp->getType().isNull()) {
14651 IsConst = false;
14652 return true;
14653 }
14654
14655 // FIXME: Evaluating values of large array and record types can cause
14656 // performance problems. Only do so in C++11 for now.
14657 if (Exp->isPRValue() &&
14658 (Exp->getType()->isArrayType() || Exp->getType()->isRecordType()) &&
14659 !Ctx.getLangOpts().CPlusPlus11) {
14660 IsConst = false;
14661 return true;
14662 }
14663 return false;
14664 }
14665
hasUnacceptableSideEffect(Expr::EvalStatus & Result,Expr::SideEffectsKind SEK)14666 static bool hasUnacceptableSideEffect(Expr::EvalStatus &Result,
14667 Expr::SideEffectsKind SEK) {
14668 return (SEK < Expr::SE_AllowSideEffects && Result.HasSideEffects) ||
14669 (SEK < Expr::SE_AllowUndefinedBehavior && Result.HasUndefinedBehavior);
14670 }
14671
EvaluateAsRValue(const Expr * E,Expr::EvalResult & Result,const ASTContext & Ctx,EvalInfo & Info)14672 static bool EvaluateAsRValue(const Expr *E, Expr::EvalResult &Result,
14673 const ASTContext &Ctx, EvalInfo &Info) {
14674 assert(!E->isValueDependent());
14675 bool IsConst;
14676 if (FastEvaluateAsRValue(E, Result, Ctx, IsConst))
14677 return IsConst;
14678
14679 return EvaluateAsRValue(Info, E, Result.Val);
14680 }
14681
EvaluateAsInt(const Expr * E,Expr::EvalResult & ExprResult,const ASTContext & Ctx,Expr::SideEffectsKind AllowSideEffects,EvalInfo & Info)14682 static bool EvaluateAsInt(const Expr *E, Expr::EvalResult &ExprResult,
14683 const ASTContext &Ctx,
14684 Expr::SideEffectsKind AllowSideEffects,
14685 EvalInfo &Info) {
14686 assert(!E->isValueDependent());
14687 if (!E->getType()->isIntegralOrEnumerationType())
14688 return false;
14689
14690 if (!::EvaluateAsRValue(E, ExprResult, Ctx, Info) ||
14691 !ExprResult.Val.isInt() ||
14692 hasUnacceptableSideEffect(ExprResult, AllowSideEffects))
14693 return false;
14694
14695 return true;
14696 }
14697
EvaluateAsFixedPoint(const Expr * E,Expr::EvalResult & ExprResult,const ASTContext & Ctx,Expr::SideEffectsKind AllowSideEffects,EvalInfo & Info)14698 static bool EvaluateAsFixedPoint(const Expr *E, Expr::EvalResult &ExprResult,
14699 const ASTContext &Ctx,
14700 Expr::SideEffectsKind AllowSideEffects,
14701 EvalInfo &Info) {
14702 assert(!E->isValueDependent());
14703 if (!E->getType()->isFixedPointType())
14704 return false;
14705
14706 if (!::EvaluateAsRValue(E, ExprResult, Ctx, Info))
14707 return false;
14708
14709 if (!ExprResult.Val.isFixedPoint() ||
14710 hasUnacceptableSideEffect(ExprResult, AllowSideEffects))
14711 return false;
14712
14713 return true;
14714 }
14715
14716 /// EvaluateAsRValue - Return true if this is a constant which we can fold using
14717 /// any crazy technique (that has nothing to do with language standards) that
14718 /// we want to. If this function returns true, it returns the folded constant
14719 /// in Result. If this expression is a glvalue, an lvalue-to-rvalue conversion
14720 /// will be applied to the result.
EvaluateAsRValue(EvalResult & Result,const ASTContext & Ctx,bool InConstantContext) const14721 bool Expr::EvaluateAsRValue(EvalResult &Result, const ASTContext &Ctx,
14722 bool InConstantContext) const {
14723 assert(!isValueDependent() &&
14724 "Expression evaluator can't be called on a dependent expression.");
14725 EvalInfo Info(Ctx, Result, EvalInfo::EM_IgnoreSideEffects);
14726 Info.InConstantContext = InConstantContext;
14727 return ::EvaluateAsRValue(this, Result, Ctx, Info);
14728 }
14729
EvaluateAsBooleanCondition(bool & Result,const ASTContext & Ctx,bool InConstantContext) const14730 bool Expr::EvaluateAsBooleanCondition(bool &Result, const ASTContext &Ctx,
14731 bool InConstantContext) const {
14732 assert(!isValueDependent() &&
14733 "Expression evaluator can't be called on a dependent expression.");
14734 EvalResult Scratch;
14735 return EvaluateAsRValue(Scratch, Ctx, InConstantContext) &&
14736 HandleConversionToBool(Scratch.Val, Result);
14737 }
14738
EvaluateAsInt(EvalResult & Result,const ASTContext & Ctx,SideEffectsKind AllowSideEffects,bool InConstantContext) const14739 bool Expr::EvaluateAsInt(EvalResult &Result, const ASTContext &Ctx,
14740 SideEffectsKind AllowSideEffects,
14741 bool InConstantContext) const {
14742 assert(!isValueDependent() &&
14743 "Expression evaluator can't be called on a dependent expression.");
14744 EvalInfo Info(Ctx, Result, EvalInfo::EM_IgnoreSideEffects);
14745 Info.InConstantContext = InConstantContext;
14746 return ::EvaluateAsInt(this, Result, Ctx, AllowSideEffects, Info);
14747 }
14748
EvaluateAsFixedPoint(EvalResult & Result,const ASTContext & Ctx,SideEffectsKind AllowSideEffects,bool InConstantContext) const14749 bool Expr::EvaluateAsFixedPoint(EvalResult &Result, const ASTContext &Ctx,
14750 SideEffectsKind AllowSideEffects,
14751 bool InConstantContext) const {
14752 assert(!isValueDependent() &&
14753 "Expression evaluator can't be called on a dependent expression.");
14754 EvalInfo Info(Ctx, Result, EvalInfo::EM_IgnoreSideEffects);
14755 Info.InConstantContext = InConstantContext;
14756 return ::EvaluateAsFixedPoint(this, Result, Ctx, AllowSideEffects, Info);
14757 }
14758
EvaluateAsFloat(APFloat & Result,const ASTContext & Ctx,SideEffectsKind AllowSideEffects,bool InConstantContext) const14759 bool Expr::EvaluateAsFloat(APFloat &Result, const ASTContext &Ctx,
14760 SideEffectsKind AllowSideEffects,
14761 bool InConstantContext) const {
14762 assert(!isValueDependent() &&
14763 "Expression evaluator can't be called on a dependent expression.");
14764
14765 if (!getType()->isRealFloatingType())
14766 return false;
14767
14768 EvalResult ExprResult;
14769 if (!EvaluateAsRValue(ExprResult, Ctx, InConstantContext) ||
14770 !ExprResult.Val.isFloat() ||
14771 hasUnacceptableSideEffect(ExprResult, AllowSideEffects))
14772 return false;
14773
14774 Result = ExprResult.Val.getFloat();
14775 return true;
14776 }
14777
EvaluateAsLValue(EvalResult & Result,const ASTContext & Ctx,bool InConstantContext) const14778 bool Expr::EvaluateAsLValue(EvalResult &Result, const ASTContext &Ctx,
14779 bool InConstantContext) const {
14780 assert(!isValueDependent() &&
14781 "Expression evaluator can't be called on a dependent expression.");
14782
14783 EvalInfo Info(Ctx, Result, EvalInfo::EM_ConstantFold);
14784 Info.InConstantContext = InConstantContext;
14785 LValue LV;
14786 CheckedTemporaries CheckedTemps;
14787 if (!EvaluateLValue(this, LV, Info) || !Info.discardCleanups() ||
14788 Result.HasSideEffects ||
14789 !CheckLValueConstantExpression(Info, getExprLoc(),
14790 Ctx.getLValueReferenceType(getType()), LV,
14791 ConstantExprKind::Normal, CheckedTemps))
14792 return false;
14793
14794 LV.moveInto(Result.Val);
14795 return true;
14796 }
14797
EvaluateDestruction(const ASTContext & Ctx,APValue::LValueBase Base,APValue DestroyedValue,QualType Type,SourceLocation Loc,Expr::EvalStatus & EStatus,bool IsConstantDestruction)14798 static bool EvaluateDestruction(const ASTContext &Ctx, APValue::LValueBase Base,
14799 APValue DestroyedValue, QualType Type,
14800 SourceLocation Loc, Expr::EvalStatus &EStatus,
14801 bool IsConstantDestruction) {
14802 EvalInfo Info(Ctx, EStatus,
14803 IsConstantDestruction ? EvalInfo::EM_ConstantExpression
14804 : EvalInfo::EM_ConstantFold);
14805 Info.setEvaluatingDecl(Base, DestroyedValue,
14806 EvalInfo::EvaluatingDeclKind::Dtor);
14807 Info.InConstantContext = IsConstantDestruction;
14808
14809 LValue LVal;
14810 LVal.set(Base);
14811
14812 if (!HandleDestruction(Info, Loc, Base, DestroyedValue, Type) ||
14813 EStatus.HasSideEffects)
14814 return false;
14815
14816 if (!Info.discardCleanups())
14817 llvm_unreachable("Unhandled cleanup; missing full expression marker?");
14818
14819 return true;
14820 }
14821
EvaluateAsConstantExpr(EvalResult & Result,const ASTContext & Ctx,ConstantExprKind Kind) const14822 bool Expr::EvaluateAsConstantExpr(EvalResult &Result, const ASTContext &Ctx,
14823 ConstantExprKind Kind) const {
14824 assert(!isValueDependent() &&
14825 "Expression evaluator can't be called on a dependent expression.");
14826
14827 EvalInfo::EvaluationMode EM = EvalInfo::EM_ConstantExpression;
14828 EvalInfo Info(Ctx, Result, EM);
14829 Info.InConstantContext = true;
14830
14831 // The type of the object we're initializing is 'const T' for a class NTTP.
14832 QualType T = getType();
14833 if (Kind == ConstantExprKind::ClassTemplateArgument)
14834 T.addConst();
14835
14836 // If we're evaluating a prvalue, fake up a MaterializeTemporaryExpr to
14837 // represent the result of the evaluation. CheckConstantExpression ensures
14838 // this doesn't escape.
14839 MaterializeTemporaryExpr BaseMTE(T, const_cast<Expr*>(this), true);
14840 APValue::LValueBase Base(&BaseMTE);
14841
14842 Info.setEvaluatingDecl(Base, Result.Val);
14843 LValue LVal;
14844 LVal.set(Base);
14845
14846 if (!::EvaluateInPlace(Result.Val, Info, LVal, this) || Result.HasSideEffects)
14847 return false;
14848
14849 if (!Info.discardCleanups())
14850 llvm_unreachable("Unhandled cleanup; missing full expression marker?");
14851
14852 if (!CheckConstantExpression(Info, getExprLoc(), getStorageType(Ctx, this),
14853 Result.Val, Kind))
14854 return false;
14855 if (!CheckMemoryLeaks(Info))
14856 return false;
14857
14858 // If this is a class template argument, it's required to have constant
14859 // destruction too.
14860 if (Kind == ConstantExprKind::ClassTemplateArgument &&
14861 (!EvaluateDestruction(Ctx, Base, Result.Val, T, getBeginLoc(), Result,
14862 true) ||
14863 Result.HasSideEffects)) {
14864 // FIXME: Prefix a note to indicate that the problem is lack of constant
14865 // destruction.
14866 return false;
14867 }
14868
14869 return true;
14870 }
14871
EvaluateAsInitializer(APValue & Value,const ASTContext & Ctx,const VarDecl * VD,SmallVectorImpl<PartialDiagnosticAt> & Notes,bool IsConstantInitialization) const14872 bool Expr::EvaluateAsInitializer(APValue &Value, const ASTContext &Ctx,
14873 const VarDecl *VD,
14874 SmallVectorImpl<PartialDiagnosticAt> &Notes,
14875 bool IsConstantInitialization) const {
14876 assert(!isValueDependent() &&
14877 "Expression evaluator can't be called on a dependent expression.");
14878
14879 // FIXME: Evaluating initializers for large array and record types can cause
14880 // performance problems. Only do so in C++11 for now.
14881 if (isPRValue() && (getType()->isArrayType() || getType()->isRecordType()) &&
14882 !Ctx.getLangOpts().CPlusPlus11)
14883 return false;
14884
14885 Expr::EvalStatus EStatus;
14886 EStatus.Diag = &Notes;
14887
14888 EvalInfo Info(Ctx, EStatus,
14889 (IsConstantInitialization && Ctx.getLangOpts().CPlusPlus11)
14890 ? EvalInfo::EM_ConstantExpression
14891 : EvalInfo::EM_ConstantFold);
14892 Info.setEvaluatingDecl(VD, Value);
14893 Info.InConstantContext = IsConstantInitialization;
14894
14895 SourceLocation DeclLoc = VD->getLocation();
14896 QualType DeclTy = VD->getType();
14897
14898 if (Info.EnableNewConstInterp) {
14899 auto &InterpCtx = const_cast<ASTContext &>(Ctx).getInterpContext();
14900 if (!InterpCtx.evaluateAsInitializer(Info, VD, Value))
14901 return false;
14902 } else {
14903 LValue LVal;
14904 LVal.set(VD);
14905
14906 if (!EvaluateInPlace(Value, Info, LVal, this,
14907 /*AllowNonLiteralTypes=*/true) ||
14908 EStatus.HasSideEffects)
14909 return false;
14910
14911 // At this point, any lifetime-extended temporaries are completely
14912 // initialized.
14913 Info.performLifetimeExtension();
14914
14915 if (!Info.discardCleanups())
14916 llvm_unreachable("Unhandled cleanup; missing full expression marker?");
14917 }
14918 return CheckConstantExpression(Info, DeclLoc, DeclTy, Value,
14919 ConstantExprKind::Normal) &&
14920 CheckMemoryLeaks(Info);
14921 }
14922
evaluateDestruction(SmallVectorImpl<PartialDiagnosticAt> & Notes) const14923 bool VarDecl::evaluateDestruction(
14924 SmallVectorImpl<PartialDiagnosticAt> &Notes) const {
14925 Expr::EvalStatus EStatus;
14926 EStatus.Diag = &Notes;
14927
14928 // Only treat the destruction as constant destruction if we formally have
14929 // constant initialization (or are usable in a constant expression).
14930 bool IsConstantDestruction = hasConstantInitialization();
14931
14932 // Make a copy of the value for the destructor to mutate, if we know it.
14933 // Otherwise, treat the value as default-initialized; if the destructor works
14934 // anyway, then the destruction is constant (and must be essentially empty).
14935 APValue DestroyedValue;
14936 if (getEvaluatedValue() && !getEvaluatedValue()->isAbsent())
14937 DestroyedValue = *getEvaluatedValue();
14938 else if (!getDefaultInitValue(getType(), DestroyedValue))
14939 return false;
14940
14941 if (!EvaluateDestruction(getASTContext(), this, std::move(DestroyedValue),
14942 getType(), getLocation(), EStatus,
14943 IsConstantDestruction) ||
14944 EStatus.HasSideEffects)
14945 return false;
14946
14947 ensureEvaluatedStmt()->HasConstantDestruction = true;
14948 return true;
14949 }
14950
14951 /// isEvaluatable - Call EvaluateAsRValue to see if this expression can be
14952 /// constant folded, but discard the result.
isEvaluatable(const ASTContext & Ctx,SideEffectsKind SEK) const14953 bool Expr::isEvaluatable(const ASTContext &Ctx, SideEffectsKind SEK) const {
14954 assert(!isValueDependent() &&
14955 "Expression evaluator can't be called on a dependent expression.");
14956
14957 EvalResult Result;
14958 return EvaluateAsRValue(Result, Ctx, /* in constant context */ true) &&
14959 !hasUnacceptableSideEffect(Result, SEK);
14960 }
14961
EvaluateKnownConstInt(const ASTContext & Ctx,SmallVectorImpl<PartialDiagnosticAt> * Diag) const14962 APSInt Expr::EvaluateKnownConstInt(const ASTContext &Ctx,
14963 SmallVectorImpl<PartialDiagnosticAt> *Diag) const {
14964 assert(!isValueDependent() &&
14965 "Expression evaluator can't be called on a dependent expression.");
14966
14967 EvalResult EVResult;
14968 EVResult.Diag = Diag;
14969 EvalInfo Info(Ctx, EVResult, EvalInfo::EM_IgnoreSideEffects);
14970 Info.InConstantContext = true;
14971
14972 bool Result = ::EvaluateAsRValue(this, EVResult, Ctx, Info);
14973 (void)Result;
14974 assert(Result && "Could not evaluate expression");
14975 assert(EVResult.Val.isInt() && "Expression did not evaluate to integer");
14976
14977 return EVResult.Val.getInt();
14978 }
14979
EvaluateKnownConstIntCheckOverflow(const ASTContext & Ctx,SmallVectorImpl<PartialDiagnosticAt> * Diag) const14980 APSInt Expr::EvaluateKnownConstIntCheckOverflow(
14981 const ASTContext &Ctx, SmallVectorImpl<PartialDiagnosticAt> *Diag) const {
14982 assert(!isValueDependent() &&
14983 "Expression evaluator can't be called on a dependent expression.");
14984
14985 EvalResult EVResult;
14986 EVResult.Diag = Diag;
14987 EvalInfo Info(Ctx, EVResult, EvalInfo::EM_IgnoreSideEffects);
14988 Info.InConstantContext = true;
14989 Info.CheckingForUndefinedBehavior = true;
14990
14991 bool Result = ::EvaluateAsRValue(Info, this, EVResult.Val);
14992 (void)Result;
14993 assert(Result && "Could not evaluate expression");
14994 assert(EVResult.Val.isInt() && "Expression did not evaluate to integer");
14995
14996 return EVResult.Val.getInt();
14997 }
14998
EvaluateForOverflow(const ASTContext & Ctx) const14999 void Expr::EvaluateForOverflow(const ASTContext &Ctx) const {
15000 assert(!isValueDependent() &&
15001 "Expression evaluator can't be called on a dependent expression.");
15002
15003 bool IsConst;
15004 EvalResult EVResult;
15005 if (!FastEvaluateAsRValue(this, EVResult, Ctx, IsConst)) {
15006 EvalInfo Info(Ctx, EVResult, EvalInfo::EM_IgnoreSideEffects);
15007 Info.CheckingForUndefinedBehavior = true;
15008 (void)::EvaluateAsRValue(Info, this, EVResult.Val);
15009 }
15010 }
15011
isGlobalLValue() const15012 bool Expr::EvalResult::isGlobalLValue() const {
15013 assert(Val.isLValue());
15014 return IsGlobalLValue(Val.getLValueBase());
15015 }
15016
15017 /// isIntegerConstantExpr - this recursive routine will test if an expression is
15018 /// an integer constant expression.
15019
15020 /// FIXME: Pass up a reason why! Invalid operation in i-c-e, division by zero,
15021 /// comma, etc
15022
15023 // CheckICE - This function does the fundamental ICE checking: the returned
15024 // ICEDiag contains an ICEKind indicating whether the expression is an ICE,
15025 // and a (possibly null) SourceLocation indicating the location of the problem.
15026 //
15027 // Note that to reduce code duplication, this helper does no evaluation
15028 // itself; the caller checks whether the expression is evaluatable, and
15029 // in the rare cases where CheckICE actually cares about the evaluated
15030 // value, it calls into Evaluate.
15031
15032 namespace {
15033
15034 enum ICEKind {
15035 /// This expression is an ICE.
15036 IK_ICE,
15037 /// This expression is not an ICE, but if it isn't evaluated, it's
15038 /// a legal subexpression for an ICE. This return value is used to handle
15039 /// the comma operator in C99 mode, and non-constant subexpressions.
15040 IK_ICEIfUnevaluated,
15041 /// This expression is not an ICE, and is not a legal subexpression for one.
15042 IK_NotICE
15043 };
15044
15045 struct ICEDiag {
15046 ICEKind Kind;
15047 SourceLocation Loc;
15048
ICEDiag__anon4a4db2533511::ICEDiag15049 ICEDiag(ICEKind IK, SourceLocation l) : Kind(IK), Loc(l) {}
15050 };
15051
15052 }
15053
NoDiag()15054 static ICEDiag NoDiag() { return ICEDiag(IK_ICE, SourceLocation()); }
15055
Worst(ICEDiag A,ICEDiag B)15056 static ICEDiag Worst(ICEDiag A, ICEDiag B) { return A.Kind >= B.Kind ? A : B; }
15057
CheckEvalInICE(const Expr * E,const ASTContext & Ctx)15058 static ICEDiag CheckEvalInICE(const Expr* E, const ASTContext &Ctx) {
15059 Expr::EvalResult EVResult;
15060 Expr::EvalStatus Status;
15061 EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantExpression);
15062
15063 Info.InConstantContext = true;
15064 if (!::EvaluateAsRValue(E, EVResult, Ctx, Info) || EVResult.HasSideEffects ||
15065 !EVResult.Val.isInt())
15066 return ICEDiag(IK_NotICE, E->getBeginLoc());
15067
15068 return NoDiag();
15069 }
15070
CheckICE(const Expr * E,const ASTContext & Ctx)15071 static ICEDiag CheckICE(const Expr* E, const ASTContext &Ctx) {
15072 assert(!E->isValueDependent() && "Should not see value dependent exprs!");
15073 if (!E->getType()->isIntegralOrEnumerationType())
15074 return ICEDiag(IK_NotICE, E->getBeginLoc());
15075
15076 switch (E->getStmtClass()) {
15077 #define ABSTRACT_STMT(Node)
15078 #define STMT(Node, Base) case Expr::Node##Class:
15079 #define EXPR(Node, Base)
15080 #include "clang/AST/StmtNodes.inc"
15081 case Expr::PredefinedExprClass:
15082 case Expr::FloatingLiteralClass:
15083 case Expr::ImaginaryLiteralClass:
15084 case Expr::StringLiteralClass:
15085 case Expr::ArraySubscriptExprClass:
15086 case Expr::MatrixSubscriptExprClass:
15087 case Expr::OMPArraySectionExprClass:
15088 case Expr::OMPArrayShapingExprClass:
15089 case Expr::OMPIteratorExprClass:
15090 case Expr::MemberExprClass:
15091 case Expr::CompoundAssignOperatorClass:
15092 case Expr::CompoundLiteralExprClass:
15093 case Expr::ExtVectorElementExprClass:
15094 case Expr::DesignatedInitExprClass:
15095 case Expr::ArrayInitLoopExprClass:
15096 case Expr::ArrayInitIndexExprClass:
15097 case Expr::NoInitExprClass:
15098 case Expr::DesignatedInitUpdateExprClass:
15099 case Expr::ImplicitValueInitExprClass:
15100 case Expr::ParenListExprClass:
15101 case Expr::VAArgExprClass:
15102 case Expr::AddrLabelExprClass:
15103 case Expr::StmtExprClass:
15104 case Expr::CXXMemberCallExprClass:
15105 case Expr::CUDAKernelCallExprClass:
15106 case Expr::CXXAddrspaceCastExprClass:
15107 case Expr::CXXDynamicCastExprClass:
15108 case Expr::CXXTypeidExprClass:
15109 case Expr::CXXUuidofExprClass:
15110 case Expr::MSPropertyRefExprClass:
15111 case Expr::MSPropertySubscriptExprClass:
15112 case Expr::CXXNullPtrLiteralExprClass:
15113 case Expr::UserDefinedLiteralClass:
15114 case Expr::CXXThisExprClass:
15115 case Expr::CXXThrowExprClass:
15116 case Expr::CXXNewExprClass:
15117 case Expr::CXXDeleteExprClass:
15118 case Expr::CXXPseudoDestructorExprClass:
15119 case Expr::UnresolvedLookupExprClass:
15120 case Expr::TypoExprClass:
15121 case Expr::RecoveryExprClass:
15122 case Expr::DependentScopeDeclRefExprClass:
15123 case Expr::CXXConstructExprClass:
15124 case Expr::CXXInheritedCtorInitExprClass:
15125 case Expr::CXXStdInitializerListExprClass:
15126 case Expr::CXXBindTemporaryExprClass:
15127 case Expr::ExprWithCleanupsClass:
15128 case Expr::CXXTemporaryObjectExprClass:
15129 case Expr::CXXUnresolvedConstructExprClass:
15130 case Expr::CXXDependentScopeMemberExprClass:
15131 case Expr::UnresolvedMemberExprClass:
15132 case Expr::ObjCStringLiteralClass:
15133 case Expr::ObjCBoxedExprClass:
15134 case Expr::ObjCArrayLiteralClass:
15135 case Expr::ObjCDictionaryLiteralClass:
15136 case Expr::ObjCEncodeExprClass:
15137 case Expr::ObjCMessageExprClass:
15138 case Expr::ObjCSelectorExprClass:
15139 case Expr::ObjCProtocolExprClass:
15140 case Expr::ObjCIvarRefExprClass:
15141 case Expr::ObjCPropertyRefExprClass:
15142 case Expr::ObjCSubscriptRefExprClass:
15143 case Expr::ObjCIsaExprClass:
15144 case Expr::ObjCAvailabilityCheckExprClass:
15145 case Expr::ShuffleVectorExprClass:
15146 case Expr::ConvertVectorExprClass:
15147 case Expr::BlockExprClass:
15148 case Expr::NoStmtClass:
15149 case Expr::OpaqueValueExprClass:
15150 case Expr::PackExpansionExprClass:
15151 case Expr::SubstNonTypeTemplateParmPackExprClass:
15152 case Expr::FunctionParmPackExprClass:
15153 case Expr::AsTypeExprClass:
15154 case Expr::ObjCIndirectCopyRestoreExprClass:
15155 case Expr::MaterializeTemporaryExprClass:
15156 case Expr::PseudoObjectExprClass:
15157 case Expr::AtomicExprClass:
15158 case Expr::LambdaExprClass:
15159 case Expr::CXXFoldExprClass:
15160 case Expr::CoawaitExprClass:
15161 case Expr::DependentCoawaitExprClass:
15162 case Expr::CoyieldExprClass:
15163 case Expr::SYCLUniqueStableNameExprClass:
15164 return ICEDiag(IK_NotICE, E->getBeginLoc());
15165
15166 case Expr::InitListExprClass: {
15167 // C++03 [dcl.init]p13: If T is a scalar type, then a declaration of the
15168 // form "T x = { a };" is equivalent to "T x = a;".
15169 // Unless we're initializing a reference, T is a scalar as it is known to be
15170 // of integral or enumeration type.
15171 if (E->isPRValue())
15172 if (cast<InitListExpr>(E)->getNumInits() == 1)
15173 return CheckICE(cast<InitListExpr>(E)->getInit(0), Ctx);
15174 return ICEDiag(IK_NotICE, E->getBeginLoc());
15175 }
15176
15177 case Expr::SizeOfPackExprClass:
15178 case Expr::GNUNullExprClass:
15179 case Expr::SourceLocExprClass:
15180 return NoDiag();
15181
15182 case Expr::SubstNonTypeTemplateParmExprClass:
15183 return
15184 CheckICE(cast<SubstNonTypeTemplateParmExpr>(E)->getReplacement(), Ctx);
15185
15186 case Expr::ConstantExprClass:
15187 return CheckICE(cast<ConstantExpr>(E)->getSubExpr(), Ctx);
15188
15189 case Expr::ParenExprClass:
15190 return CheckICE(cast<ParenExpr>(E)->getSubExpr(), Ctx);
15191 case Expr::GenericSelectionExprClass:
15192 return CheckICE(cast<GenericSelectionExpr>(E)->getResultExpr(), Ctx);
15193 case Expr::IntegerLiteralClass:
15194 case Expr::FixedPointLiteralClass:
15195 case Expr::CharacterLiteralClass:
15196 case Expr::ObjCBoolLiteralExprClass:
15197 case Expr::CXXBoolLiteralExprClass:
15198 case Expr::CXXScalarValueInitExprClass:
15199 case Expr::TypeTraitExprClass:
15200 case Expr::ConceptSpecializationExprClass:
15201 case Expr::RequiresExprClass:
15202 case Expr::ArrayTypeTraitExprClass:
15203 case Expr::ExpressionTraitExprClass:
15204 case Expr::CXXNoexceptExprClass:
15205 return NoDiag();
15206 case Expr::CallExprClass:
15207 case Expr::CXXOperatorCallExprClass: {
15208 // C99 6.6/3 allows function calls within unevaluated subexpressions of
15209 // constant expressions, but they can never be ICEs because an ICE cannot
15210 // contain an operand of (pointer to) function type.
15211 const CallExpr *CE = cast<CallExpr>(E);
15212 if (CE->getBuiltinCallee())
15213 return CheckEvalInICE(E, Ctx);
15214 return ICEDiag(IK_NotICE, E->getBeginLoc());
15215 }
15216 case Expr::CXXRewrittenBinaryOperatorClass:
15217 return CheckICE(cast<CXXRewrittenBinaryOperator>(E)->getSemanticForm(),
15218 Ctx);
15219 case Expr::DeclRefExprClass: {
15220 const NamedDecl *D = cast<DeclRefExpr>(E)->getDecl();
15221 if (isa<EnumConstantDecl>(D))
15222 return NoDiag();
15223
15224 // C++ and OpenCL (FIXME: spec reference?) allow reading const-qualified
15225 // integer variables in constant expressions:
15226 //
15227 // C++ 7.1.5.1p2
15228 // A variable of non-volatile const-qualified integral or enumeration
15229 // type initialized by an ICE can be used in ICEs.
15230 //
15231 // We sometimes use CheckICE to check the C++98 rules in C++11 mode. In
15232 // that mode, use of reference variables should not be allowed.
15233 const VarDecl *VD = dyn_cast<VarDecl>(D);
15234 if (VD && VD->isUsableInConstantExpressions(Ctx) &&
15235 !VD->getType()->isReferenceType())
15236 return NoDiag();
15237
15238 return ICEDiag(IK_NotICE, E->getBeginLoc());
15239 }
15240 case Expr::UnaryOperatorClass: {
15241 const UnaryOperator *Exp = cast<UnaryOperator>(E);
15242 switch (Exp->getOpcode()) {
15243 case UO_PostInc:
15244 case UO_PostDec:
15245 case UO_PreInc:
15246 case UO_PreDec:
15247 case UO_AddrOf:
15248 case UO_Deref:
15249 case UO_Coawait:
15250 // C99 6.6/3 allows increment and decrement within unevaluated
15251 // subexpressions of constant expressions, but they can never be ICEs
15252 // because an ICE cannot contain an lvalue operand.
15253 return ICEDiag(IK_NotICE, E->getBeginLoc());
15254 case UO_Extension:
15255 case UO_LNot:
15256 case UO_Plus:
15257 case UO_Minus:
15258 case UO_Not:
15259 case UO_Real:
15260 case UO_Imag:
15261 return CheckICE(Exp->getSubExpr(), Ctx);
15262 }
15263 llvm_unreachable("invalid unary operator class");
15264 }
15265 case Expr::OffsetOfExprClass: {
15266 // Note that per C99, offsetof must be an ICE. And AFAIK, using
15267 // EvaluateAsRValue matches the proposed gcc behavior for cases like
15268 // "offsetof(struct s{int x[4];}, x[1.0])". This doesn't affect
15269 // compliance: we should warn earlier for offsetof expressions with
15270 // array subscripts that aren't ICEs, and if the array subscripts
15271 // are ICEs, the value of the offsetof must be an integer constant.
15272 return CheckEvalInICE(E, Ctx);
15273 }
15274 case Expr::UnaryExprOrTypeTraitExprClass: {
15275 const UnaryExprOrTypeTraitExpr *Exp = cast<UnaryExprOrTypeTraitExpr>(E);
15276 if ((Exp->getKind() == UETT_SizeOf) &&
15277 Exp->getTypeOfArgument()->isVariableArrayType())
15278 return ICEDiag(IK_NotICE, E->getBeginLoc());
15279 return NoDiag();
15280 }
15281 case Expr::BinaryOperatorClass: {
15282 const BinaryOperator *Exp = cast<BinaryOperator>(E);
15283 switch (Exp->getOpcode()) {
15284 case BO_PtrMemD:
15285 case BO_PtrMemI:
15286 case BO_Assign:
15287 case BO_MulAssign:
15288 case BO_DivAssign:
15289 case BO_RemAssign:
15290 case BO_AddAssign:
15291 case BO_SubAssign:
15292 case BO_ShlAssign:
15293 case BO_ShrAssign:
15294 case BO_AndAssign:
15295 case BO_XorAssign:
15296 case BO_OrAssign:
15297 // C99 6.6/3 allows assignments within unevaluated subexpressions of
15298 // constant expressions, but they can never be ICEs because an ICE cannot
15299 // contain an lvalue operand.
15300 return ICEDiag(IK_NotICE, E->getBeginLoc());
15301
15302 case BO_Mul:
15303 case BO_Div:
15304 case BO_Rem:
15305 case BO_Add:
15306 case BO_Sub:
15307 case BO_Shl:
15308 case BO_Shr:
15309 case BO_LT:
15310 case BO_GT:
15311 case BO_LE:
15312 case BO_GE:
15313 case BO_EQ:
15314 case BO_NE:
15315 case BO_And:
15316 case BO_Xor:
15317 case BO_Or:
15318 case BO_Comma:
15319 case BO_Cmp: {
15320 ICEDiag LHSResult = CheckICE(Exp->getLHS(), Ctx);
15321 ICEDiag RHSResult = CheckICE(Exp->getRHS(), Ctx);
15322 if (Exp->getOpcode() == BO_Div ||
15323 Exp->getOpcode() == BO_Rem) {
15324 // EvaluateAsRValue gives an error for undefined Div/Rem, so make sure
15325 // we don't evaluate one.
15326 if (LHSResult.Kind == IK_ICE && RHSResult.Kind == IK_ICE) {
15327 llvm::APSInt REval = Exp->getRHS()->EvaluateKnownConstInt(Ctx);
15328 if (REval == 0)
15329 return ICEDiag(IK_ICEIfUnevaluated, E->getBeginLoc());
15330 if (REval.isSigned() && REval.isAllOnes()) {
15331 llvm::APSInt LEval = Exp->getLHS()->EvaluateKnownConstInt(Ctx);
15332 if (LEval.isMinSignedValue())
15333 return ICEDiag(IK_ICEIfUnevaluated, E->getBeginLoc());
15334 }
15335 }
15336 }
15337 if (Exp->getOpcode() == BO_Comma) {
15338 if (Ctx.getLangOpts().C99) {
15339 // C99 6.6p3 introduces a strange edge case: comma can be in an ICE
15340 // if it isn't evaluated.
15341 if (LHSResult.Kind == IK_ICE && RHSResult.Kind == IK_ICE)
15342 return ICEDiag(IK_ICEIfUnevaluated, E->getBeginLoc());
15343 } else {
15344 // In both C89 and C++, commas in ICEs are illegal.
15345 return ICEDiag(IK_NotICE, E->getBeginLoc());
15346 }
15347 }
15348 return Worst(LHSResult, RHSResult);
15349 }
15350 case BO_LAnd:
15351 case BO_LOr: {
15352 ICEDiag LHSResult = CheckICE(Exp->getLHS(), Ctx);
15353 ICEDiag RHSResult = CheckICE(Exp->getRHS(), Ctx);
15354 if (LHSResult.Kind == IK_ICE && RHSResult.Kind == IK_ICEIfUnevaluated) {
15355 // Rare case where the RHS has a comma "side-effect"; we need
15356 // to actually check the condition to see whether the side
15357 // with the comma is evaluated.
15358 if ((Exp->getOpcode() == BO_LAnd) !=
15359 (Exp->getLHS()->EvaluateKnownConstInt(Ctx) == 0))
15360 return RHSResult;
15361 return NoDiag();
15362 }
15363
15364 return Worst(LHSResult, RHSResult);
15365 }
15366 }
15367 llvm_unreachable("invalid binary operator kind");
15368 }
15369 case Expr::ImplicitCastExprClass:
15370 case Expr::CStyleCastExprClass:
15371 case Expr::CXXFunctionalCastExprClass:
15372 case Expr::CXXStaticCastExprClass:
15373 case Expr::CXXReinterpretCastExprClass:
15374 case Expr::CXXConstCastExprClass:
15375 case Expr::ObjCBridgedCastExprClass: {
15376 const Expr *SubExpr = cast<CastExpr>(E)->getSubExpr();
15377 if (isa<ExplicitCastExpr>(E)) {
15378 if (const FloatingLiteral *FL
15379 = dyn_cast<FloatingLiteral>(SubExpr->IgnoreParenImpCasts())) {
15380 unsigned DestWidth = Ctx.getIntWidth(E->getType());
15381 bool DestSigned = E->getType()->isSignedIntegerOrEnumerationType();
15382 APSInt IgnoredVal(DestWidth, !DestSigned);
15383 bool Ignored;
15384 // If the value does not fit in the destination type, the behavior is
15385 // undefined, so we are not required to treat it as a constant
15386 // expression.
15387 if (FL->getValue().convertToInteger(IgnoredVal,
15388 llvm::APFloat::rmTowardZero,
15389 &Ignored) & APFloat::opInvalidOp)
15390 return ICEDiag(IK_NotICE, E->getBeginLoc());
15391 return NoDiag();
15392 }
15393 }
15394 switch (cast<CastExpr>(E)->getCastKind()) {
15395 case CK_LValueToRValue:
15396 case CK_AtomicToNonAtomic:
15397 case CK_NonAtomicToAtomic:
15398 case CK_NoOp:
15399 case CK_IntegralToBoolean:
15400 case CK_IntegralCast:
15401 return CheckICE(SubExpr, Ctx);
15402 default:
15403 return ICEDiag(IK_NotICE, E->getBeginLoc());
15404 }
15405 }
15406 case Expr::BinaryConditionalOperatorClass: {
15407 const BinaryConditionalOperator *Exp = cast<BinaryConditionalOperator>(E);
15408 ICEDiag CommonResult = CheckICE(Exp->getCommon(), Ctx);
15409 if (CommonResult.Kind == IK_NotICE) return CommonResult;
15410 ICEDiag FalseResult = CheckICE(Exp->getFalseExpr(), Ctx);
15411 if (FalseResult.Kind == IK_NotICE) return FalseResult;
15412 if (CommonResult.Kind == IK_ICEIfUnevaluated) return CommonResult;
15413 if (FalseResult.Kind == IK_ICEIfUnevaluated &&
15414 Exp->getCommon()->EvaluateKnownConstInt(Ctx) != 0) return NoDiag();
15415 return FalseResult;
15416 }
15417 case Expr::ConditionalOperatorClass: {
15418 const ConditionalOperator *Exp = cast<ConditionalOperator>(E);
15419 // If the condition (ignoring parens) is a __builtin_constant_p call,
15420 // then only the true side is actually considered in an integer constant
15421 // expression, and it is fully evaluated. This is an important GNU
15422 // extension. See GCC PR38377 for discussion.
15423 if (const CallExpr *CallCE
15424 = dyn_cast<CallExpr>(Exp->getCond()->IgnoreParenCasts()))
15425 if (CallCE->getBuiltinCallee() == Builtin::BI__builtin_constant_p)
15426 return CheckEvalInICE(E, Ctx);
15427 ICEDiag CondResult = CheckICE(Exp->getCond(), Ctx);
15428 if (CondResult.Kind == IK_NotICE)
15429 return CondResult;
15430
15431 ICEDiag TrueResult = CheckICE(Exp->getTrueExpr(), Ctx);
15432 ICEDiag FalseResult = CheckICE(Exp->getFalseExpr(), Ctx);
15433
15434 if (TrueResult.Kind == IK_NotICE)
15435 return TrueResult;
15436 if (FalseResult.Kind == IK_NotICE)
15437 return FalseResult;
15438 if (CondResult.Kind == IK_ICEIfUnevaluated)
15439 return CondResult;
15440 if (TrueResult.Kind == IK_ICE && FalseResult.Kind == IK_ICE)
15441 return NoDiag();
15442 // Rare case where the diagnostics depend on which side is evaluated
15443 // Note that if we get here, CondResult is 0, and at least one of
15444 // TrueResult and FalseResult is non-zero.
15445 if (Exp->getCond()->EvaluateKnownConstInt(Ctx) == 0)
15446 return FalseResult;
15447 return TrueResult;
15448 }
15449 case Expr::CXXDefaultArgExprClass:
15450 return CheckICE(cast<CXXDefaultArgExpr>(E)->getExpr(), Ctx);
15451 case Expr::CXXDefaultInitExprClass:
15452 return CheckICE(cast<CXXDefaultInitExpr>(E)->getExpr(), Ctx);
15453 case Expr::ChooseExprClass: {
15454 return CheckICE(cast<ChooseExpr>(E)->getChosenSubExpr(), Ctx);
15455 }
15456 case Expr::BuiltinBitCastExprClass: {
15457 if (!checkBitCastConstexprEligibility(nullptr, Ctx, cast<CastExpr>(E)))
15458 return ICEDiag(IK_NotICE, E->getBeginLoc());
15459 return CheckICE(cast<CastExpr>(E)->getSubExpr(), Ctx);
15460 }
15461 }
15462
15463 llvm_unreachable("Invalid StmtClass!");
15464 }
15465
15466 /// Evaluate an expression as a C++11 integral constant expression.
EvaluateCPlusPlus11IntegralConstantExpr(const ASTContext & Ctx,const Expr * E,llvm::APSInt * Value,SourceLocation * Loc)15467 static bool EvaluateCPlusPlus11IntegralConstantExpr(const ASTContext &Ctx,
15468 const Expr *E,
15469 llvm::APSInt *Value,
15470 SourceLocation *Loc) {
15471 if (!E->getType()->isIntegralOrUnscopedEnumerationType()) {
15472 if (Loc) *Loc = E->getExprLoc();
15473 return false;
15474 }
15475
15476 APValue Result;
15477 if (!E->isCXX11ConstantExpr(Ctx, &Result, Loc))
15478 return false;
15479
15480 if (!Result.isInt()) {
15481 if (Loc) *Loc = E->getExprLoc();
15482 return false;
15483 }
15484
15485 if (Value) *Value = Result.getInt();
15486 return true;
15487 }
15488
isIntegerConstantExpr(const ASTContext & Ctx,SourceLocation * Loc) const15489 bool Expr::isIntegerConstantExpr(const ASTContext &Ctx,
15490 SourceLocation *Loc) const {
15491 assert(!isValueDependent() &&
15492 "Expression evaluator can't be called on a dependent expression.");
15493
15494 if (Ctx.getLangOpts().CPlusPlus11)
15495 return EvaluateCPlusPlus11IntegralConstantExpr(Ctx, this, nullptr, Loc);
15496
15497 ICEDiag D = CheckICE(this, Ctx);
15498 if (D.Kind != IK_ICE) {
15499 if (Loc) *Loc = D.Loc;
15500 return false;
15501 }
15502 return true;
15503 }
15504
getIntegerConstantExpr(const ASTContext & Ctx,SourceLocation * Loc,bool isEvaluated) const15505 Optional<llvm::APSInt> Expr::getIntegerConstantExpr(const ASTContext &Ctx,
15506 SourceLocation *Loc,
15507 bool isEvaluated) const {
15508 assert(!isValueDependent() &&
15509 "Expression evaluator can't be called on a dependent expression.");
15510
15511 APSInt Value;
15512
15513 if (Ctx.getLangOpts().CPlusPlus11) {
15514 if (EvaluateCPlusPlus11IntegralConstantExpr(Ctx, this, &Value, Loc))
15515 return Value;
15516 return None;
15517 }
15518
15519 if (!isIntegerConstantExpr(Ctx, Loc))
15520 return None;
15521
15522 // The only possible side-effects here are due to UB discovered in the
15523 // evaluation (for instance, INT_MAX + 1). In such a case, we are still
15524 // required to treat the expression as an ICE, so we produce the folded
15525 // value.
15526 EvalResult ExprResult;
15527 Expr::EvalStatus Status;
15528 EvalInfo Info(Ctx, Status, EvalInfo::EM_IgnoreSideEffects);
15529 Info.InConstantContext = true;
15530
15531 if (!::EvaluateAsInt(this, ExprResult, Ctx, SE_AllowSideEffects, Info))
15532 llvm_unreachable("ICE cannot be evaluated!");
15533
15534 return ExprResult.Val.getInt();
15535 }
15536
isCXX98IntegralConstantExpr(const ASTContext & Ctx) const15537 bool Expr::isCXX98IntegralConstantExpr(const ASTContext &Ctx) const {
15538 assert(!isValueDependent() &&
15539 "Expression evaluator can't be called on a dependent expression.");
15540
15541 return CheckICE(this, Ctx).Kind == IK_ICE;
15542 }
15543
isCXX11ConstantExpr(const ASTContext & Ctx,APValue * Result,SourceLocation * Loc) const15544 bool Expr::isCXX11ConstantExpr(const ASTContext &Ctx, APValue *Result,
15545 SourceLocation *Loc) const {
15546 assert(!isValueDependent() &&
15547 "Expression evaluator can't be called on a dependent expression.");
15548
15549 // We support this checking in C++98 mode in order to diagnose compatibility
15550 // issues.
15551 assert(Ctx.getLangOpts().CPlusPlus);
15552
15553 // Build evaluation settings.
15554 Expr::EvalStatus Status;
15555 SmallVector<PartialDiagnosticAt, 8> Diags;
15556 Status.Diag = &Diags;
15557 EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantExpression);
15558
15559 APValue Scratch;
15560 bool IsConstExpr =
15561 ::EvaluateAsRValue(Info, this, Result ? *Result : Scratch) &&
15562 // FIXME: We don't produce a diagnostic for this, but the callers that
15563 // call us on arbitrary full-expressions should generally not care.
15564 Info.discardCleanups() && !Status.HasSideEffects;
15565
15566 if (!Diags.empty()) {
15567 IsConstExpr = false;
15568 if (Loc) *Loc = Diags[0].first;
15569 } else if (!IsConstExpr) {
15570 // FIXME: This shouldn't happen.
15571 if (Loc) *Loc = getExprLoc();
15572 }
15573
15574 return IsConstExpr;
15575 }
15576
EvaluateWithSubstitution(APValue & Value,ASTContext & Ctx,const FunctionDecl * Callee,ArrayRef<const Expr * > Args,const Expr * This) const15577 bool Expr::EvaluateWithSubstitution(APValue &Value, ASTContext &Ctx,
15578 const FunctionDecl *Callee,
15579 ArrayRef<const Expr*> Args,
15580 const Expr *This) const {
15581 assert(!isValueDependent() &&
15582 "Expression evaluator can't be called on a dependent expression.");
15583
15584 Expr::EvalStatus Status;
15585 EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantExpressionUnevaluated);
15586 Info.InConstantContext = true;
15587
15588 LValue ThisVal;
15589 const LValue *ThisPtr = nullptr;
15590 if (This) {
15591 #ifndef NDEBUG
15592 auto *MD = dyn_cast<CXXMethodDecl>(Callee);
15593 assert(MD && "Don't provide `this` for non-methods.");
15594 assert(!MD->isStatic() && "Don't provide `this` for static methods.");
15595 #endif
15596 if (!This->isValueDependent() &&
15597 EvaluateObjectArgument(Info, This, ThisVal) &&
15598 !Info.EvalStatus.HasSideEffects)
15599 ThisPtr = &ThisVal;
15600
15601 // Ignore any side-effects from a failed evaluation. This is safe because
15602 // they can't interfere with any other argument evaluation.
15603 Info.EvalStatus.HasSideEffects = false;
15604 }
15605
15606 CallRef Call = Info.CurrentCall->createCall(Callee);
15607 for (ArrayRef<const Expr*>::iterator I = Args.begin(), E = Args.end();
15608 I != E; ++I) {
15609 unsigned Idx = I - Args.begin();
15610 if (Idx >= Callee->getNumParams())
15611 break;
15612 const ParmVarDecl *PVD = Callee->getParamDecl(Idx);
15613 if ((*I)->isValueDependent() ||
15614 !EvaluateCallArg(PVD, *I, Call, Info) ||
15615 Info.EvalStatus.HasSideEffects) {
15616 // If evaluation fails, throw away the argument entirely.
15617 if (APValue *Slot = Info.getParamSlot(Call, PVD))
15618 *Slot = APValue();
15619 }
15620
15621 // Ignore any side-effects from a failed evaluation. This is safe because
15622 // they can't interfere with any other argument evaluation.
15623 Info.EvalStatus.HasSideEffects = false;
15624 }
15625
15626 // Parameter cleanups happen in the caller and are not part of this
15627 // evaluation.
15628 Info.discardCleanups();
15629 Info.EvalStatus.HasSideEffects = false;
15630
15631 // Build fake call to Callee.
15632 CallStackFrame Frame(Info, Callee->getLocation(), Callee, ThisPtr, Call);
15633 // FIXME: Missing ExprWithCleanups in enable_if conditions?
15634 FullExpressionRAII Scope(Info);
15635 return Evaluate(Value, Info, this) && Scope.destroy() &&
15636 !Info.EvalStatus.HasSideEffects;
15637 }
15638
isPotentialConstantExpr(const FunctionDecl * FD,SmallVectorImpl<PartialDiagnosticAt> & Diags)15639 bool Expr::isPotentialConstantExpr(const FunctionDecl *FD,
15640 SmallVectorImpl<
15641 PartialDiagnosticAt> &Diags) {
15642 // FIXME: It would be useful to check constexpr function templates, but at the
15643 // moment the constant expression evaluator cannot cope with the non-rigorous
15644 // ASTs which we build for dependent expressions.
15645 if (FD->isDependentContext())
15646 return true;
15647
15648 Expr::EvalStatus Status;
15649 Status.Diag = &Diags;
15650
15651 EvalInfo Info(FD->getASTContext(), Status, EvalInfo::EM_ConstantExpression);
15652 Info.InConstantContext = true;
15653 Info.CheckingPotentialConstantExpression = true;
15654
15655 // The constexpr VM attempts to compile all methods to bytecode here.
15656 if (Info.EnableNewConstInterp) {
15657 Info.Ctx.getInterpContext().isPotentialConstantExpr(Info, FD);
15658 return Diags.empty();
15659 }
15660
15661 const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD);
15662 const CXXRecordDecl *RD = MD ? MD->getParent()->getCanonicalDecl() : nullptr;
15663
15664 // Fabricate an arbitrary expression on the stack and pretend that it
15665 // is a temporary being used as the 'this' pointer.
15666 LValue This;
15667 ImplicitValueInitExpr VIE(RD ? Info.Ctx.getRecordType(RD) : Info.Ctx.IntTy);
15668 This.set({&VIE, Info.CurrentCall->Index});
15669
15670 ArrayRef<const Expr*> Args;
15671
15672 APValue Scratch;
15673 if (const CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(FD)) {
15674 // Evaluate the call as a constant initializer, to allow the construction
15675 // of objects of non-literal types.
15676 Info.setEvaluatingDecl(This.getLValueBase(), Scratch);
15677 HandleConstructorCall(&VIE, This, Args, CD, Info, Scratch);
15678 } else {
15679 SourceLocation Loc = FD->getLocation();
15680 HandleFunctionCall(Loc, FD, (MD && MD->isInstance()) ? &This : nullptr,
15681 Args, CallRef(), FD->getBody(), Info, Scratch, nullptr);
15682 }
15683
15684 return Diags.empty();
15685 }
15686
isPotentialConstantExprUnevaluated(Expr * E,const FunctionDecl * FD,SmallVectorImpl<PartialDiagnosticAt> & Diags)15687 bool Expr::isPotentialConstantExprUnevaluated(Expr *E,
15688 const FunctionDecl *FD,
15689 SmallVectorImpl<
15690 PartialDiagnosticAt> &Diags) {
15691 assert(!E->isValueDependent() &&
15692 "Expression evaluator can't be called on a dependent expression.");
15693
15694 Expr::EvalStatus Status;
15695 Status.Diag = &Diags;
15696
15697 EvalInfo Info(FD->getASTContext(), Status,
15698 EvalInfo::EM_ConstantExpressionUnevaluated);
15699 Info.InConstantContext = true;
15700 Info.CheckingPotentialConstantExpression = true;
15701
15702 // Fabricate a call stack frame to give the arguments a plausible cover story.
15703 CallStackFrame Frame(Info, SourceLocation(), FD, /*This*/ nullptr, CallRef());
15704
15705 APValue ResultScratch;
15706 Evaluate(ResultScratch, Info, E);
15707 return Diags.empty();
15708 }
15709
tryEvaluateObjectSize(uint64_t & Result,ASTContext & Ctx,unsigned Type) const15710 bool Expr::tryEvaluateObjectSize(uint64_t &Result, ASTContext &Ctx,
15711 unsigned Type) const {
15712 if (!getType()->isPointerType())
15713 return false;
15714
15715 Expr::EvalStatus Status;
15716 EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantFold);
15717 return tryEvaluateBuiltinObjectSize(this, Type, Info, Result);
15718 }
15719
EvaluateBuiltinStrLen(const Expr * E,uint64_t & Result,EvalInfo & Info)15720 static bool EvaluateBuiltinStrLen(const Expr *E, uint64_t &Result,
15721 EvalInfo &Info) {
15722 if (!E->getType()->hasPointerRepresentation() || !E->isPRValue())
15723 return false;
15724
15725 LValue String;
15726
15727 if (!EvaluatePointer(E, String, Info))
15728 return false;
15729
15730 QualType CharTy = E->getType()->getPointeeType();
15731
15732 // Fast path: if it's a string literal, search the string value.
15733 if (const StringLiteral *S = dyn_cast_or_null<StringLiteral>(
15734 String.getLValueBase().dyn_cast<const Expr *>())) {
15735 StringRef Str = S->getBytes();
15736 int64_t Off = String.Offset.getQuantity();
15737 if (Off >= 0 && (uint64_t)Off <= (uint64_t)Str.size() &&
15738 S->getCharByteWidth() == 1 &&
15739 // FIXME: Add fast-path for wchar_t too.
15740 Info.Ctx.hasSameUnqualifiedType(CharTy, Info.Ctx.CharTy)) {
15741 Str = Str.substr(Off);
15742
15743 StringRef::size_type Pos = Str.find(0);
15744 if (Pos != StringRef::npos)
15745 Str = Str.substr(0, Pos);
15746
15747 Result = Str.size();
15748 return true;
15749 }
15750
15751 // Fall through to slow path.
15752 }
15753
15754 // Slow path: scan the bytes of the string looking for the terminating 0.
15755 for (uint64_t Strlen = 0; /**/; ++Strlen) {
15756 APValue Char;
15757 if (!handleLValueToRValueConversion(Info, E, CharTy, String, Char) ||
15758 !Char.isInt())
15759 return false;
15760 if (!Char.getInt()) {
15761 Result = Strlen;
15762 return true;
15763 }
15764 if (!HandleLValueArrayAdjustment(Info, E, String, CharTy, 1))
15765 return false;
15766 }
15767 }
15768
tryEvaluateStrLen(uint64_t & Result,ASTContext & Ctx) const15769 bool Expr::tryEvaluateStrLen(uint64_t &Result, ASTContext &Ctx) const {
15770 Expr::EvalStatus Status;
15771 EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantFold);
15772 return EvaluateBuiltinStrLen(this, Result, Info);
15773 }
15774