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->isRValue())
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__anon6b379bbb0111::SubobjectDesignator272 SubobjectDesignator() : Invalid(true) {}
273
SubobjectDesignator__anon6b379bbb0111::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__anon6b379bbb0111::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__anon6b379bbb0111::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__anon6b379bbb0111::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__anon6b379bbb0111::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__anon6b379bbb0111::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__anon6b379bbb0111::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__anon6b379bbb0111::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__anon6b379bbb0111::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__anon6b379bbb0111::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__anon6b379bbb0111::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__anon6b379bbb0111::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__anon6b379bbb0111::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__anon6b379bbb0111::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__anon6b379bbb0111::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__anon6b379bbb0111::CallRef495 CallRef() : OrigCallee(), CallIndex(0), Version() {}
CallRef__anon6b379bbb0111::CallRef496 CallRef(const FunctionDecl *Callee, unsigned CallIndex, unsigned Version)
497 : OrigCallee(Callee), CallIndex(CallIndex), Version(Version) {}
498
operator bool__anon6b379bbb0111::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__anon6b379bbb0111::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__anon6b379bbb0311::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 ()__anon6b379bbb0311::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__anon6b379bbb0311::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__anon6b379bbb0311::EvalInfo::EvaluatingConstructorRAII867 void finishedConstructingBases() {
868 EI.ObjectsUnderConstruction[Object] = ConstructionPhase::AfterBases;
869 }
finishedConstructingFields__anon6b379bbb0311::EvalInfo::EvaluatingConstructorRAII870 void finishedConstructingFields() {
871 EI.ObjectsUnderConstruction[Object] = ConstructionPhase::AfterFields;
872 }
~EvaluatingConstructorRAII__anon6b379bbb0311::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__anon6b379bbb0311::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__anon6b379bbb0311::EvalInfo::EvaluatingDestructorRAII888 void startedDestroyingBases() {
889 EI.ObjectsUnderConstruction[Object] =
890 ConstructionPhase::DestroyingBases;
891 }
~EvaluatingDestructorRAII__anon6b379bbb0311::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__anon6b379bbb0311::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__anon6b379bbb0311::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__anon6b379bbb0311::FoldConstant1271 void keepDiagnostics() { Enabled = false; }
~FoldConstant__anon6b379bbb0311::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__anon6b379bbb0311::IgnoreSideEffectsRAII1285 explicit IgnoreSideEffectsRAII(EvalInfo &Info)
1286 : Info(Info), OldMode(Info.EvalMode) {
1287 Info.EvalMode = EvalInfo::EM_IgnoreSideEffects;
1288 }
1289
~IgnoreSideEffectsRAII__anon6b379bbb0311::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__anon6b379bbb0611::ComplexValue1517 ComplexValue() : FloatReal(APFloat::Bogus()), FloatImag(APFloat::Bogus()) {}
1518
makeComplexFloat__anon6b379bbb0611::ComplexValue1519 void makeComplexFloat() { IsInt = false; }
isComplexFloat__anon6b379bbb0611::ComplexValue1520 bool isComplexFloat() const { return !IsInt; }
getComplexFloatReal__anon6b379bbb0611::ComplexValue1521 APFloat &getComplexFloatReal() { return FloatReal; }
getComplexFloatImag__anon6b379bbb0611::ComplexValue1522 APFloat &getComplexFloatImag() { return FloatImag; }
1523
makeComplexInt__anon6b379bbb0611::ComplexValue1524 void makeComplexInt() { IsInt = true; }
isComplexInt__anon6b379bbb0611::ComplexValue1525 bool isComplexInt() const { return IsInt; }
getComplexIntReal__anon6b379bbb0611::ComplexValue1526 APSInt &getComplexIntReal() { return IntReal; }
getComplexIntImag__anon6b379bbb0611::ComplexValue1527 APSInt &getComplexIntImag() { return IntImag; }
1528
moveInto__anon6b379bbb0611::ComplexValue1529 void moveInto(APValue &v) const {
1530 if (isComplexFloat())
1531 v = APValue(FloatReal, FloatImag);
1532 else
1533 v = APValue(IntReal, IntImag);
1534 }
setFrom__anon6b379bbb0611::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__anon6b379bbb0611::LValue1556 const APValue::LValueBase getLValueBase() const { return Base; }
getLValueOffset__anon6b379bbb0611::LValue1557 CharUnits &getLValueOffset() { return Offset; }
getLValueOffset__anon6b379bbb0611::LValue1558 const CharUnits &getLValueOffset() const { return Offset; }
getLValueDesignator__anon6b379bbb0611::LValue1559 SubobjectDesignator &getLValueDesignator() { return Designator; }
getLValueDesignator__anon6b379bbb0611::LValue1560 const SubobjectDesignator &getLValueDesignator() const { return Designator;}
isNullPointer__anon6b379bbb0611::LValue1561 bool isNullPointer() const { return IsNullPtr;}
1562
getLValueCallIndex__anon6b379bbb0611::LValue1563 unsigned getLValueCallIndex() const { return Base.getCallIndex(); }
getLValueVersion__anon6b379bbb0611::LValue1564 unsigned getLValueVersion() const { return Base.getVersion(); }
1565
moveInto__anon6b379bbb0611::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__anon6b379bbb0611::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__anon6b379bbb0611::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__anon6b379bbb0611::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__anon6b379bbb0611::LValue1610 void setInvalid(APValue::LValueBase B, unsigned I = 0) {
1611 set(B, true);
1612 }
1613
toString__anon6b379bbb0611::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__anon6b379bbb0611::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__anon6b379bbb0611::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__anon6b379bbb0611::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__anon6b379bbb0611::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__anon6b379bbb0611::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__anon6b379bbb0611::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__anon6b379bbb0611::LValue1674 void addArray(EvalInfo &Info, const Expr *E, const ConstantArrayType *CAT) {
1675 if (checkSubobject(Info, E, CSK_ArrayToPointer))
1676 Designator.addArrayUnchecked(CAT);
1677 }
addComplex__anon6b379bbb0611::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__anon6b379bbb0611::LValue1682 void clearIsNullPointer() {
1683 IsNullPtr = false;
1684 }
adjustOffsetAndIndex__anon6b379bbb0611::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__anon6b379bbb0611::LValue1704 void adjustOffset(CharUnits N) {
1705 Offset += N;
1706 if (N.getQuantity())
1707 clearIsNullPointer();
1708 }
1709 };
1710
1711 struct MemberPtr {
MemberPtr__anon6b379bbb0611::MemberPtr1712 MemberPtr() {}
MemberPtr__anon6b379bbb0611::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__anon6b379bbb0611::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__anon6b379bbb0611::MemberPtr1722 bool isDerivedMember() const {
1723 return DeclAndIsDerivedMember.getInt();
1724 }
1725 /// Get the class which the declaration actually lives in.
getContainingRecord__anon6b379bbb0611::MemberPtr1726 const CXXRecordDecl *getContainingRecord() const {
1727 return cast<CXXRecordDecl>(
1728 DeclAndIsDerivedMember.getPointer()->getDeclContext());
1729 }
1730
moveInto__anon6b379bbb0611::MemberPtr1731 void moveInto(APValue &V) const {
1732 V = APValue(getDecl(), isDerivedMember(), Path);
1733 }
setFrom__anon6b379bbb0611::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__anon6b379bbb0611::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__anon6b379bbb0611::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__anon6b379bbb0611::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
1830 /// Evaluate an integer or fixed point expression into an APResult.
1831 static bool EvaluateFixedPointOrInteger(const Expr *E, APFixedPoint &Result,
1832 EvalInfo &Info);
1833
1834 /// Evaluate only a fixed point expression into an APResult.
1835 static bool EvaluateFixedPoint(const Expr *E, APFixedPoint &Result,
1836 EvalInfo &Info);
1837
1838 //===----------------------------------------------------------------------===//
1839 // Misc utilities
1840 //===----------------------------------------------------------------------===//
1841
1842 /// Negate an APSInt in place, converting it to a signed form if necessary, and
1843 /// preserving its value (by extending by up to one bit as needed).
negateAsSigned(APSInt & Int)1844 static void negateAsSigned(APSInt &Int) {
1845 if (Int.isUnsigned() || Int.isMinSignedValue()) {
1846 Int = Int.extend(Int.getBitWidth() + 1);
1847 Int.setIsSigned(true);
1848 }
1849 Int = -Int;
1850 }
1851
1852 template<typename KeyT>
createTemporary(const KeyT * Key,QualType T,ScopeKind Scope,LValue & LV)1853 APValue &CallStackFrame::createTemporary(const KeyT *Key, QualType T,
1854 ScopeKind Scope, LValue &LV) {
1855 unsigned Version = getTempVersion();
1856 APValue::LValueBase Base(Key, Index, Version);
1857 LV.set(Base);
1858 return createLocal(Base, Key, T, Scope);
1859 }
1860
1861 /// Allocate storage for a parameter of a function call made in this frame.
createParam(CallRef Args,const ParmVarDecl * PVD,LValue & LV)1862 APValue &CallStackFrame::createParam(CallRef Args, const ParmVarDecl *PVD,
1863 LValue &LV) {
1864 assert(Args.CallIndex == Index && "creating parameter in wrong frame");
1865 APValue::LValueBase Base(PVD, Index, Args.Version);
1866 LV.set(Base);
1867 // We always destroy parameters at the end of the call, even if we'd allow
1868 // them to live to the end of the full-expression at runtime, in order to
1869 // give portable results and match other compilers.
1870 return createLocal(Base, PVD, PVD->getType(), ScopeKind::Call);
1871 }
1872
createLocal(APValue::LValueBase Base,const void * Key,QualType T,ScopeKind Scope)1873 APValue &CallStackFrame::createLocal(APValue::LValueBase Base, const void *Key,
1874 QualType T, ScopeKind Scope) {
1875 assert(Base.getCallIndex() == Index && "lvalue for wrong frame");
1876 unsigned Version = Base.getVersion();
1877 APValue &Result = Temporaries[MapKeyTy(Key, Version)];
1878 assert(Result.isAbsent() && "local created multiple times");
1879
1880 // If we're creating a local immediately in the operand of a speculative
1881 // evaluation, don't register a cleanup to be run outside the speculative
1882 // evaluation context, since we won't actually be able to initialize this
1883 // object.
1884 if (Index <= Info.SpeculativeEvaluationDepth) {
1885 if (T.isDestructedType())
1886 Info.noteSideEffect();
1887 } else {
1888 Info.CleanupStack.push_back(Cleanup(&Result, Base, T, Scope));
1889 }
1890 return Result;
1891 }
1892
createHeapAlloc(const Expr * E,QualType T,LValue & LV)1893 APValue *EvalInfo::createHeapAlloc(const Expr *E, QualType T, LValue &LV) {
1894 if (NumHeapAllocs > DynamicAllocLValue::getMaxIndex()) {
1895 FFDiag(E, diag::note_constexpr_heap_alloc_limit_exceeded);
1896 return nullptr;
1897 }
1898
1899 DynamicAllocLValue DA(NumHeapAllocs++);
1900 LV.set(APValue::LValueBase::getDynamicAlloc(DA, T));
1901 auto Result = HeapAllocs.emplace(std::piecewise_construct,
1902 std::forward_as_tuple(DA), std::tuple<>());
1903 assert(Result.second && "reused a heap alloc index?");
1904 Result.first->second.AllocExpr = E;
1905 return &Result.first->second.Value;
1906 }
1907
1908 /// Produce a string describing the given constexpr call.
describe(raw_ostream & Out)1909 void CallStackFrame::describe(raw_ostream &Out) {
1910 unsigned ArgIndex = 0;
1911 bool IsMemberCall = isa<CXXMethodDecl>(Callee) &&
1912 !isa<CXXConstructorDecl>(Callee) &&
1913 cast<CXXMethodDecl>(Callee)->isInstance();
1914
1915 if (!IsMemberCall)
1916 Out << *Callee << '(';
1917
1918 if (This && IsMemberCall) {
1919 APValue Val;
1920 This->moveInto(Val);
1921 Val.printPretty(Out, Info.Ctx,
1922 This->Designator.MostDerivedType);
1923 // FIXME: Add parens around Val if needed.
1924 Out << "->" << *Callee << '(';
1925 IsMemberCall = false;
1926 }
1927
1928 for (FunctionDecl::param_const_iterator I = Callee->param_begin(),
1929 E = Callee->param_end(); I != E; ++I, ++ArgIndex) {
1930 if (ArgIndex > (unsigned)IsMemberCall)
1931 Out << ", ";
1932
1933 const ParmVarDecl *Param = *I;
1934 APValue *V = Info.getParamSlot(Arguments, Param);
1935 if (V)
1936 V->printPretty(Out, Info.Ctx, Param->getType());
1937 else
1938 Out << "<...>";
1939
1940 if (ArgIndex == 0 && IsMemberCall)
1941 Out << "->" << *Callee << '(';
1942 }
1943
1944 Out << ')';
1945 }
1946
1947 /// Evaluate an expression to see if it had side-effects, and discard its
1948 /// result.
1949 /// \return \c true if the caller should keep evaluating.
EvaluateIgnoredValue(EvalInfo & Info,const Expr * E)1950 static bool EvaluateIgnoredValue(EvalInfo &Info, const Expr *E) {
1951 assert(!E->isValueDependent());
1952 APValue Scratch;
1953 if (!Evaluate(Scratch, Info, E))
1954 // We don't need the value, but we might have skipped a side effect here.
1955 return Info.noteSideEffect();
1956 return true;
1957 }
1958
1959 /// Should this call expression be treated as a string literal?
IsStringLiteralCall(const CallExpr * E)1960 static bool IsStringLiteralCall(const CallExpr *E) {
1961 unsigned Builtin = E->getBuiltinCallee();
1962 return (Builtin == Builtin::BI__builtin___CFStringMakeConstantString ||
1963 Builtin == Builtin::BI__builtin___NSStringMakeConstantString);
1964 }
1965
IsGlobalLValue(APValue::LValueBase B)1966 static bool IsGlobalLValue(APValue::LValueBase B) {
1967 // C++11 [expr.const]p3 An address constant expression is a prvalue core
1968 // constant expression of pointer type that evaluates to...
1969
1970 // ... a null pointer value, or a prvalue core constant expression of type
1971 // std::nullptr_t.
1972 if (!B) return true;
1973
1974 if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) {
1975 // ... the address of an object with static storage duration,
1976 if (const VarDecl *VD = dyn_cast<VarDecl>(D))
1977 return VD->hasGlobalStorage();
1978 if (isa<TemplateParamObjectDecl>(D))
1979 return true;
1980 // ... the address of a function,
1981 // ... the address of a GUID [MS extension],
1982 return isa<FunctionDecl>(D) || isa<MSGuidDecl>(D);
1983 }
1984
1985 if (B.is<TypeInfoLValue>() || B.is<DynamicAllocLValue>())
1986 return true;
1987
1988 const Expr *E = B.get<const Expr*>();
1989 switch (E->getStmtClass()) {
1990 default:
1991 return false;
1992 case Expr::CompoundLiteralExprClass: {
1993 const CompoundLiteralExpr *CLE = cast<CompoundLiteralExpr>(E);
1994 return CLE->isFileScope() && CLE->isLValue();
1995 }
1996 case Expr::MaterializeTemporaryExprClass:
1997 // A materialized temporary might have been lifetime-extended to static
1998 // storage duration.
1999 return cast<MaterializeTemporaryExpr>(E)->getStorageDuration() == SD_Static;
2000 // A string literal has static storage duration.
2001 case Expr::StringLiteralClass:
2002 case Expr::PredefinedExprClass:
2003 case Expr::ObjCStringLiteralClass:
2004 case Expr::ObjCEncodeExprClass:
2005 return true;
2006 case Expr::ObjCBoxedExprClass:
2007 return cast<ObjCBoxedExpr>(E)->isExpressibleAsConstantInitializer();
2008 case Expr::CallExprClass:
2009 return IsStringLiteralCall(cast<CallExpr>(E));
2010 // For GCC compatibility, &&label has static storage duration.
2011 case Expr::AddrLabelExprClass:
2012 return true;
2013 // A Block literal expression may be used as the initialization value for
2014 // Block variables at global or local static scope.
2015 case Expr::BlockExprClass:
2016 return !cast<BlockExpr>(E)->getBlockDecl()->hasCaptures();
2017 case Expr::ImplicitValueInitExprClass:
2018 // FIXME:
2019 // We can never form an lvalue with an implicit value initialization as its
2020 // base through expression evaluation, so these only appear in one case: the
2021 // implicit variable declaration we invent when checking whether a constexpr
2022 // constructor can produce a constant expression. We must assume that such
2023 // an expression might be a global lvalue.
2024 return true;
2025 }
2026 }
2027
GetLValueBaseDecl(const LValue & LVal)2028 static const ValueDecl *GetLValueBaseDecl(const LValue &LVal) {
2029 return LVal.Base.dyn_cast<const ValueDecl*>();
2030 }
2031
IsLiteralLValue(const LValue & Value)2032 static bool IsLiteralLValue(const LValue &Value) {
2033 if (Value.getLValueCallIndex())
2034 return false;
2035 const Expr *E = Value.Base.dyn_cast<const Expr*>();
2036 return E && !isa<MaterializeTemporaryExpr>(E);
2037 }
2038
IsWeakLValue(const LValue & Value)2039 static bool IsWeakLValue(const LValue &Value) {
2040 const ValueDecl *Decl = GetLValueBaseDecl(Value);
2041 return Decl && Decl->isWeak();
2042 }
2043
isZeroSized(const LValue & Value)2044 static bool isZeroSized(const LValue &Value) {
2045 const ValueDecl *Decl = GetLValueBaseDecl(Value);
2046 if (Decl && isa<VarDecl>(Decl)) {
2047 QualType Ty = Decl->getType();
2048 if (Ty->isArrayType())
2049 return Ty->isIncompleteType() ||
2050 Decl->getASTContext().getTypeSize(Ty) == 0;
2051 }
2052 return false;
2053 }
2054
HasSameBase(const LValue & A,const LValue & B)2055 static bool HasSameBase(const LValue &A, const LValue &B) {
2056 if (!A.getLValueBase())
2057 return !B.getLValueBase();
2058 if (!B.getLValueBase())
2059 return false;
2060
2061 if (A.getLValueBase().getOpaqueValue() !=
2062 B.getLValueBase().getOpaqueValue())
2063 return false;
2064
2065 return A.getLValueCallIndex() == B.getLValueCallIndex() &&
2066 A.getLValueVersion() == B.getLValueVersion();
2067 }
2068
NoteLValueLocation(EvalInfo & Info,APValue::LValueBase Base)2069 static void NoteLValueLocation(EvalInfo &Info, APValue::LValueBase Base) {
2070 assert(Base && "no location for a null lvalue");
2071 const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>();
2072
2073 // For a parameter, find the corresponding call stack frame (if it still
2074 // exists), and point at the parameter of the function definition we actually
2075 // invoked.
2076 if (auto *PVD = dyn_cast_or_null<ParmVarDecl>(VD)) {
2077 unsigned Idx = PVD->getFunctionScopeIndex();
2078 for (CallStackFrame *F = Info.CurrentCall; F; F = F->Caller) {
2079 if (F->Arguments.CallIndex == Base.getCallIndex() &&
2080 F->Arguments.Version == Base.getVersion() && F->Callee &&
2081 Idx < F->Callee->getNumParams()) {
2082 VD = F->Callee->getParamDecl(Idx);
2083 break;
2084 }
2085 }
2086 }
2087
2088 if (VD)
2089 Info.Note(VD->getLocation(), diag::note_declared_at);
2090 else if (const Expr *E = Base.dyn_cast<const Expr*>())
2091 Info.Note(E->getExprLoc(), diag::note_constexpr_temporary_here);
2092 else if (DynamicAllocLValue DA = Base.dyn_cast<DynamicAllocLValue>()) {
2093 // FIXME: Produce a note for dangling pointers too.
2094 if (Optional<DynAlloc*> Alloc = Info.lookupDynamicAlloc(DA))
2095 Info.Note((*Alloc)->AllocExpr->getExprLoc(),
2096 diag::note_constexpr_dynamic_alloc_here);
2097 }
2098 // We have no information to show for a typeid(T) object.
2099 }
2100
2101 enum class CheckEvaluationResultKind {
2102 ConstantExpression,
2103 FullyInitialized,
2104 };
2105
2106 /// Materialized temporaries that we've already checked to determine if they're
2107 /// initializsed by a constant expression.
2108 using CheckedTemporaries =
2109 llvm::SmallPtrSet<const MaterializeTemporaryExpr *, 8>;
2110
2111 static bool CheckEvaluationResult(CheckEvaluationResultKind CERK,
2112 EvalInfo &Info, SourceLocation DiagLoc,
2113 QualType Type, const APValue &Value,
2114 ConstantExprKind Kind,
2115 SourceLocation SubobjectLoc,
2116 CheckedTemporaries &CheckedTemps);
2117
2118 /// Check that this reference or pointer core constant expression is a valid
2119 /// value for an address or reference constant expression. Return true if we
2120 /// 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)2121 static bool CheckLValueConstantExpression(EvalInfo &Info, SourceLocation Loc,
2122 QualType Type, const LValue &LVal,
2123 ConstantExprKind Kind,
2124 CheckedTemporaries &CheckedTemps) {
2125 bool IsReferenceType = Type->isReferenceType();
2126
2127 APValue::LValueBase Base = LVal.getLValueBase();
2128 const SubobjectDesignator &Designator = LVal.getLValueDesignator();
2129
2130 const Expr *BaseE = Base.dyn_cast<const Expr *>();
2131 const ValueDecl *BaseVD = Base.dyn_cast<const ValueDecl*>();
2132
2133 // Additional restrictions apply in a template argument. We only enforce the
2134 // C++20 restrictions here; additional syntactic and semantic restrictions
2135 // are applied elsewhere.
2136 if (isTemplateArgument(Kind)) {
2137 int InvalidBaseKind = -1;
2138 StringRef Ident;
2139 if (Base.is<TypeInfoLValue>())
2140 InvalidBaseKind = 0;
2141 else if (isa_and_nonnull<StringLiteral>(BaseE))
2142 InvalidBaseKind = 1;
2143 else if (isa_and_nonnull<MaterializeTemporaryExpr>(BaseE) ||
2144 isa_and_nonnull<LifetimeExtendedTemporaryDecl>(BaseVD))
2145 InvalidBaseKind = 2;
2146 else if (auto *PE = dyn_cast_or_null<PredefinedExpr>(BaseE)) {
2147 InvalidBaseKind = 3;
2148 Ident = PE->getIdentKindName();
2149 }
2150
2151 if (InvalidBaseKind != -1) {
2152 Info.FFDiag(Loc, diag::note_constexpr_invalid_template_arg)
2153 << IsReferenceType << !Designator.Entries.empty() << InvalidBaseKind
2154 << Ident;
2155 return false;
2156 }
2157 }
2158
2159 if (auto *FD = dyn_cast_or_null<FunctionDecl>(BaseVD)) {
2160 if (FD->isConsteval()) {
2161 Info.FFDiag(Loc, diag::note_consteval_address_accessible)
2162 << !Type->isAnyPointerType();
2163 Info.Note(FD->getLocation(), diag::note_declared_at);
2164 return false;
2165 }
2166 }
2167
2168 // Check that the object is a global. Note that the fake 'this' object we
2169 // manufacture when checking potential constant expressions is conservatively
2170 // assumed to be global here.
2171 if (!IsGlobalLValue(Base)) {
2172 if (Info.getLangOpts().CPlusPlus11) {
2173 const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>();
2174 Info.FFDiag(Loc, diag::note_constexpr_non_global, 1)
2175 << IsReferenceType << !Designator.Entries.empty()
2176 << !!VD << VD;
2177
2178 auto *VarD = dyn_cast_or_null<VarDecl>(VD);
2179 if (VarD && VarD->isConstexpr()) {
2180 // Non-static local constexpr variables have unintuitive semantics:
2181 // constexpr int a = 1;
2182 // constexpr const int *p = &a;
2183 // ... is invalid because the address of 'a' is not constant. Suggest
2184 // adding a 'static' in this case.
2185 Info.Note(VarD->getLocation(), diag::note_constexpr_not_static)
2186 << VarD
2187 << FixItHint::CreateInsertion(VarD->getBeginLoc(), "static ");
2188 } else {
2189 NoteLValueLocation(Info, Base);
2190 }
2191 } else {
2192 Info.FFDiag(Loc);
2193 }
2194 // Don't allow references to temporaries to escape.
2195 return false;
2196 }
2197 assert((Info.checkingPotentialConstantExpression() ||
2198 LVal.getLValueCallIndex() == 0) &&
2199 "have call index for global lvalue");
2200
2201 if (Base.is<DynamicAllocLValue>()) {
2202 Info.FFDiag(Loc, diag::note_constexpr_dynamic_alloc)
2203 << IsReferenceType << !Designator.Entries.empty();
2204 NoteLValueLocation(Info, Base);
2205 return false;
2206 }
2207
2208 if (BaseVD) {
2209 if (const VarDecl *Var = dyn_cast<const VarDecl>(BaseVD)) {
2210 // Check if this is a thread-local variable.
2211 if (Var->getTLSKind())
2212 // FIXME: Diagnostic!
2213 return false;
2214
2215 // A dllimport variable never acts like a constant, unless we're
2216 // evaluating a value for use only in name mangling.
2217 if (!isForManglingOnly(Kind) && Var->hasAttr<DLLImportAttr>())
2218 // FIXME: Diagnostic!
2219 return false;
2220 }
2221 if (const auto *FD = dyn_cast<const FunctionDecl>(BaseVD)) {
2222 // __declspec(dllimport) must be handled very carefully:
2223 // We must never initialize an expression with the thunk in C++.
2224 // Doing otherwise would allow the same id-expression to yield
2225 // different addresses for the same function in different translation
2226 // units. However, this means that we must dynamically initialize the
2227 // expression with the contents of the import address table at runtime.
2228 //
2229 // The C language has no notion of ODR; furthermore, it has no notion of
2230 // dynamic initialization. This means that we are permitted to
2231 // perform initialization with the address of the thunk.
2232 if (Info.getLangOpts().CPlusPlus && !isForManglingOnly(Kind) &&
2233 FD->hasAttr<DLLImportAttr>())
2234 // FIXME: Diagnostic!
2235 return false;
2236 }
2237 } else if (const auto *MTE =
2238 dyn_cast_or_null<MaterializeTemporaryExpr>(BaseE)) {
2239 if (CheckedTemps.insert(MTE).second) {
2240 QualType TempType = getType(Base);
2241 if (TempType.isDestructedType()) {
2242 Info.FFDiag(MTE->getExprLoc(),
2243 diag::note_constexpr_unsupported_temporary_nontrivial_dtor)
2244 << TempType;
2245 return false;
2246 }
2247
2248 APValue *V = MTE->getOrCreateValue(false);
2249 assert(V && "evasluation result refers to uninitialised temporary");
2250 if (!CheckEvaluationResult(CheckEvaluationResultKind::ConstantExpression,
2251 Info, MTE->getExprLoc(), TempType, *V,
2252 Kind, SourceLocation(), CheckedTemps))
2253 return false;
2254 }
2255 }
2256
2257 // Allow address constant expressions to be past-the-end pointers. This is
2258 // an extension: the standard requires them to point to an object.
2259 if (!IsReferenceType)
2260 return true;
2261
2262 // A reference constant expression must refer to an object.
2263 if (!Base) {
2264 // FIXME: diagnostic
2265 Info.CCEDiag(Loc);
2266 return true;
2267 }
2268
2269 // Does this refer one past the end of some object?
2270 if (!Designator.Invalid && Designator.isOnePastTheEnd()) {
2271 Info.FFDiag(Loc, diag::note_constexpr_past_end, 1)
2272 << !Designator.Entries.empty() << !!BaseVD << BaseVD;
2273 NoteLValueLocation(Info, Base);
2274 }
2275
2276 return true;
2277 }
2278
2279 /// Member pointers are constant expressions unless they point to a
2280 /// non-virtual dllimport member function.
CheckMemberPointerConstantExpression(EvalInfo & Info,SourceLocation Loc,QualType Type,const APValue & Value,ConstantExprKind Kind)2281 static bool CheckMemberPointerConstantExpression(EvalInfo &Info,
2282 SourceLocation Loc,
2283 QualType Type,
2284 const APValue &Value,
2285 ConstantExprKind Kind) {
2286 const ValueDecl *Member = Value.getMemberPointerDecl();
2287 const auto *FD = dyn_cast_or_null<CXXMethodDecl>(Member);
2288 if (!FD)
2289 return true;
2290 if (FD->isConsteval()) {
2291 Info.FFDiag(Loc, diag::note_consteval_address_accessible) << /*pointer*/ 0;
2292 Info.Note(FD->getLocation(), diag::note_declared_at);
2293 return false;
2294 }
2295 return isForManglingOnly(Kind) || FD->isVirtual() ||
2296 !FD->hasAttr<DLLImportAttr>();
2297 }
2298
2299 /// Check that this core constant expression is of literal type, and if not,
2300 /// produce an appropriate diagnostic.
CheckLiteralType(EvalInfo & Info,const Expr * E,const LValue * This=nullptr)2301 static bool CheckLiteralType(EvalInfo &Info, const Expr *E,
2302 const LValue *This = nullptr) {
2303 if (!E->isRValue() || E->getType()->isLiteralType(Info.Ctx))
2304 return true;
2305
2306 // C++1y: A constant initializer for an object o [...] may also invoke
2307 // constexpr constructors for o and its subobjects even if those objects
2308 // are of non-literal class types.
2309 //
2310 // C++11 missed this detail for aggregates, so classes like this:
2311 // struct foo_t { union { int i; volatile int j; } u; };
2312 // are not (obviously) initializable like so:
2313 // __attribute__((__require_constant_initialization__))
2314 // static const foo_t x = {{0}};
2315 // because "i" is a subobject with non-literal initialization (due to the
2316 // volatile member of the union). See:
2317 // http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#1677
2318 // Therefore, we use the C++1y behavior.
2319 if (This && Info.EvaluatingDecl == This->getLValueBase())
2320 return true;
2321
2322 // Prvalue constant expressions must be of literal types.
2323 if (Info.getLangOpts().CPlusPlus11)
2324 Info.FFDiag(E, diag::note_constexpr_nonliteral)
2325 << E->getType();
2326 else
2327 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
2328 return false;
2329 }
2330
CheckEvaluationResult(CheckEvaluationResultKind CERK,EvalInfo & Info,SourceLocation DiagLoc,QualType Type,const APValue & Value,ConstantExprKind Kind,SourceLocation SubobjectLoc,CheckedTemporaries & CheckedTemps)2331 static bool CheckEvaluationResult(CheckEvaluationResultKind CERK,
2332 EvalInfo &Info, SourceLocation DiagLoc,
2333 QualType Type, const APValue &Value,
2334 ConstantExprKind Kind,
2335 SourceLocation SubobjectLoc,
2336 CheckedTemporaries &CheckedTemps) {
2337 if (!Value.hasValue()) {
2338 Info.FFDiag(DiagLoc, diag::note_constexpr_uninitialized)
2339 << true << Type;
2340 if (SubobjectLoc.isValid())
2341 Info.Note(SubobjectLoc, diag::note_constexpr_subobject_declared_here);
2342 return false;
2343 }
2344
2345 // We allow _Atomic(T) to be initialized from anything that T can be
2346 // initialized from.
2347 if (const AtomicType *AT = Type->getAs<AtomicType>())
2348 Type = AT->getValueType();
2349
2350 // Core issue 1454: For a literal constant expression of array or class type,
2351 // each subobject of its value shall have been initialized by a constant
2352 // expression.
2353 if (Value.isArray()) {
2354 QualType EltTy = Type->castAsArrayTypeUnsafe()->getElementType();
2355 for (unsigned I = 0, N = Value.getArrayInitializedElts(); I != N; ++I) {
2356 if (!CheckEvaluationResult(CERK, Info, DiagLoc, EltTy,
2357 Value.getArrayInitializedElt(I), Kind,
2358 SubobjectLoc, CheckedTemps))
2359 return false;
2360 }
2361 if (!Value.hasArrayFiller())
2362 return true;
2363 return CheckEvaluationResult(CERK, Info, DiagLoc, EltTy,
2364 Value.getArrayFiller(), Kind, SubobjectLoc,
2365 CheckedTemps);
2366 }
2367 if (Value.isUnion() && Value.getUnionField()) {
2368 return CheckEvaluationResult(
2369 CERK, Info, DiagLoc, Value.getUnionField()->getType(),
2370 Value.getUnionValue(), Kind, Value.getUnionField()->getLocation(),
2371 CheckedTemps);
2372 }
2373 if (Value.isStruct()) {
2374 RecordDecl *RD = Type->castAs<RecordType>()->getDecl();
2375 if (const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(RD)) {
2376 unsigned BaseIndex = 0;
2377 for (const CXXBaseSpecifier &BS : CD->bases()) {
2378 if (!CheckEvaluationResult(CERK, Info, DiagLoc, BS.getType(),
2379 Value.getStructBase(BaseIndex), Kind,
2380 BS.getBeginLoc(), CheckedTemps))
2381 return false;
2382 ++BaseIndex;
2383 }
2384 }
2385 for (const auto *I : RD->fields()) {
2386 if (I->isUnnamedBitfield())
2387 continue;
2388
2389 if (!CheckEvaluationResult(CERK, Info, DiagLoc, I->getType(),
2390 Value.getStructField(I->getFieldIndex()),
2391 Kind, I->getLocation(), CheckedTemps))
2392 return false;
2393 }
2394 }
2395
2396 if (Value.isLValue() &&
2397 CERK == CheckEvaluationResultKind::ConstantExpression) {
2398 LValue LVal;
2399 LVal.setFrom(Info.Ctx, Value);
2400 return CheckLValueConstantExpression(Info, DiagLoc, Type, LVal, Kind,
2401 CheckedTemps);
2402 }
2403
2404 if (Value.isMemberPointer() &&
2405 CERK == CheckEvaluationResultKind::ConstantExpression)
2406 return CheckMemberPointerConstantExpression(Info, DiagLoc, Type, Value, Kind);
2407
2408 // Everything else is fine.
2409 return true;
2410 }
2411
2412 /// Check that this core constant expression value is a valid value for a
2413 /// constant expression. If not, report an appropriate diagnostic. Does not
2414 /// check that the expression is of literal type.
CheckConstantExpression(EvalInfo & Info,SourceLocation DiagLoc,QualType Type,const APValue & Value,ConstantExprKind Kind)2415 static bool CheckConstantExpression(EvalInfo &Info, SourceLocation DiagLoc,
2416 QualType Type, const APValue &Value,
2417 ConstantExprKind Kind) {
2418 // Nothing to check for a constant expression of type 'cv void'.
2419 if (Type->isVoidType())
2420 return true;
2421
2422 CheckedTemporaries CheckedTemps;
2423 return CheckEvaluationResult(CheckEvaluationResultKind::ConstantExpression,
2424 Info, DiagLoc, Type, Value, Kind,
2425 SourceLocation(), CheckedTemps);
2426 }
2427
2428 /// Check that this evaluated value is fully-initialized and can be loaded by
2429 /// an lvalue-to-rvalue conversion.
CheckFullyInitialized(EvalInfo & Info,SourceLocation DiagLoc,QualType Type,const APValue & Value)2430 static bool CheckFullyInitialized(EvalInfo &Info, SourceLocation DiagLoc,
2431 QualType Type, const APValue &Value) {
2432 CheckedTemporaries CheckedTemps;
2433 return CheckEvaluationResult(
2434 CheckEvaluationResultKind::FullyInitialized, Info, DiagLoc, Type, Value,
2435 ConstantExprKind::Normal, SourceLocation(), CheckedTemps);
2436 }
2437
2438 /// Enforce C++2a [expr.const]/4.17, which disallows new-expressions unless
2439 /// "the allocated storage is deallocated within the evaluation".
CheckMemoryLeaks(EvalInfo & Info)2440 static bool CheckMemoryLeaks(EvalInfo &Info) {
2441 if (!Info.HeapAllocs.empty()) {
2442 // We can still fold to a constant despite a compile-time memory leak,
2443 // so long as the heap allocation isn't referenced in the result (we check
2444 // that in CheckConstantExpression).
2445 Info.CCEDiag(Info.HeapAllocs.begin()->second.AllocExpr,
2446 diag::note_constexpr_memory_leak)
2447 << unsigned(Info.HeapAllocs.size() - 1);
2448 }
2449 return true;
2450 }
2451
EvalPointerValueAsBool(const APValue & Value,bool & Result)2452 static bool EvalPointerValueAsBool(const APValue &Value, bool &Result) {
2453 // A null base expression indicates a null pointer. These are always
2454 // evaluatable, and they are false unless the offset is zero.
2455 if (!Value.getLValueBase()) {
2456 Result = !Value.getLValueOffset().isZero();
2457 return true;
2458 }
2459
2460 // We have a non-null base. These are generally known to be true, but if it's
2461 // a weak declaration it can be null at runtime.
2462 Result = true;
2463 const ValueDecl *Decl = Value.getLValueBase().dyn_cast<const ValueDecl*>();
2464 return !Decl || !Decl->isWeak();
2465 }
2466
HandleConversionToBool(const APValue & Val,bool & Result)2467 static bool HandleConversionToBool(const APValue &Val, bool &Result) {
2468 switch (Val.getKind()) {
2469 case APValue::None:
2470 case APValue::Indeterminate:
2471 return false;
2472 case APValue::Int:
2473 Result = Val.getInt().getBoolValue();
2474 return true;
2475 case APValue::FixedPoint:
2476 Result = Val.getFixedPoint().getBoolValue();
2477 return true;
2478 case APValue::Float:
2479 Result = !Val.getFloat().isZero();
2480 return true;
2481 case APValue::ComplexInt:
2482 Result = Val.getComplexIntReal().getBoolValue() ||
2483 Val.getComplexIntImag().getBoolValue();
2484 return true;
2485 case APValue::ComplexFloat:
2486 Result = !Val.getComplexFloatReal().isZero() ||
2487 !Val.getComplexFloatImag().isZero();
2488 return true;
2489 case APValue::LValue:
2490 return EvalPointerValueAsBool(Val, Result);
2491 case APValue::MemberPointer:
2492 Result = Val.getMemberPointerDecl();
2493 return true;
2494 case APValue::Vector:
2495 case APValue::Array:
2496 case APValue::Struct:
2497 case APValue::Union:
2498 case APValue::AddrLabelDiff:
2499 return false;
2500 }
2501
2502 llvm_unreachable("unknown APValue kind");
2503 }
2504
EvaluateAsBooleanCondition(const Expr * E,bool & Result,EvalInfo & Info)2505 static bool EvaluateAsBooleanCondition(const Expr *E, bool &Result,
2506 EvalInfo &Info) {
2507 assert(!E->isValueDependent());
2508 assert(E->isRValue() && "missing lvalue-to-rvalue conv in bool condition");
2509 APValue Val;
2510 if (!Evaluate(Val, Info, E))
2511 return false;
2512 return HandleConversionToBool(Val, Result);
2513 }
2514
2515 template<typename T>
HandleOverflow(EvalInfo & Info,const Expr * E,const T & SrcValue,QualType DestType)2516 static bool HandleOverflow(EvalInfo &Info, const Expr *E,
2517 const T &SrcValue, QualType DestType) {
2518 Info.CCEDiag(E, diag::note_constexpr_overflow)
2519 << SrcValue << DestType;
2520 return Info.noteUndefinedBehavior();
2521 }
2522
HandleFloatToIntCast(EvalInfo & Info,const Expr * E,QualType SrcType,const APFloat & Value,QualType DestType,APSInt & Result)2523 static bool HandleFloatToIntCast(EvalInfo &Info, const Expr *E,
2524 QualType SrcType, const APFloat &Value,
2525 QualType DestType, APSInt &Result) {
2526 unsigned DestWidth = Info.Ctx.getIntWidth(DestType);
2527 // Determine whether we are converting to unsigned or signed.
2528 bool DestSigned = DestType->isSignedIntegerOrEnumerationType();
2529
2530 Result = APSInt(DestWidth, !DestSigned);
2531 bool ignored;
2532 if (Value.convertToInteger(Result, llvm::APFloat::rmTowardZero, &ignored)
2533 & APFloat::opInvalidOp)
2534 return HandleOverflow(Info, E, Value, DestType);
2535 return true;
2536 }
2537
2538 /// Get rounding mode used for evaluation of the specified expression.
2539 /// \param[out] DynamicRM Is set to true is the requested rounding mode is
2540 /// dynamic.
2541 /// If rounding mode is unknown at compile time, still try to evaluate the
2542 /// expression. If the result is exact, it does not depend on rounding mode.
2543 /// So return "tonearest" mode instead of "dynamic".
getActiveRoundingMode(EvalInfo & Info,const Expr * E,bool & DynamicRM)2544 static llvm::RoundingMode getActiveRoundingMode(EvalInfo &Info, const Expr *E,
2545 bool &DynamicRM) {
2546 llvm::RoundingMode RM =
2547 E->getFPFeaturesInEffect(Info.Ctx.getLangOpts()).getRoundingMode();
2548 DynamicRM = (RM == llvm::RoundingMode::Dynamic);
2549 if (DynamicRM)
2550 RM = llvm::RoundingMode::NearestTiesToEven;
2551 return RM;
2552 }
2553
2554 /// Check if the given evaluation result is allowed for constant evaluation.
checkFloatingPointResult(EvalInfo & Info,const Expr * E,APFloat::opStatus St)2555 static bool checkFloatingPointResult(EvalInfo &Info, const Expr *E,
2556 APFloat::opStatus St) {
2557 // In a constant context, assume that any dynamic rounding mode or FP
2558 // exception state matches the default floating-point environment.
2559 if (Info.InConstantContext)
2560 return true;
2561
2562 FPOptions FPO = E->getFPFeaturesInEffect(Info.Ctx.getLangOpts());
2563 if ((St & APFloat::opInexact) &&
2564 FPO.getRoundingMode() == llvm::RoundingMode::Dynamic) {
2565 // Inexact result means that it depends on rounding mode. If the requested
2566 // mode is dynamic, the evaluation cannot be made in compile time.
2567 Info.FFDiag(E, diag::note_constexpr_dynamic_rounding);
2568 return false;
2569 }
2570
2571 if ((St != APFloat::opOK) &&
2572 (FPO.getRoundingMode() == llvm::RoundingMode::Dynamic ||
2573 FPO.getFPExceptionMode() != LangOptions::FPE_Ignore ||
2574 FPO.getAllowFEnvAccess())) {
2575 Info.FFDiag(E, diag::note_constexpr_float_arithmetic_strict);
2576 return false;
2577 }
2578
2579 if ((St & APFloat::opStatus::opInvalidOp) &&
2580 FPO.getFPExceptionMode() != LangOptions::FPE_Ignore) {
2581 // There is no usefully definable result.
2582 Info.FFDiag(E);
2583 return false;
2584 }
2585
2586 // FIXME: if:
2587 // - evaluation triggered other FP exception, and
2588 // - exception mode is not "ignore", and
2589 // - the expression being evaluated is not a part of global variable
2590 // initializer,
2591 // the evaluation probably need to be rejected.
2592 return true;
2593 }
2594
HandleFloatToFloatCast(EvalInfo & Info,const Expr * E,QualType SrcType,QualType DestType,APFloat & Result)2595 static bool HandleFloatToFloatCast(EvalInfo &Info, const Expr *E,
2596 QualType SrcType, QualType DestType,
2597 APFloat &Result) {
2598 assert(isa<CastExpr>(E) || isa<CompoundAssignOperator>(E));
2599 bool DynamicRM;
2600 llvm::RoundingMode RM = getActiveRoundingMode(Info, E, DynamicRM);
2601 APFloat::opStatus St;
2602 APFloat Value = Result;
2603 bool ignored;
2604 St = Result.convert(Info.Ctx.getFloatTypeSemantics(DestType), RM, &ignored);
2605 return checkFloatingPointResult(Info, E, St);
2606 }
2607
HandleIntToIntCast(EvalInfo & Info,const Expr * E,QualType DestType,QualType SrcType,const APSInt & Value)2608 static APSInt HandleIntToIntCast(EvalInfo &Info, const Expr *E,
2609 QualType DestType, QualType SrcType,
2610 const APSInt &Value) {
2611 unsigned DestWidth = Info.Ctx.getIntWidth(DestType);
2612 // Figure out if this is a truncate, extend or noop cast.
2613 // If the input is signed, do a sign extend, noop, or truncate.
2614 APSInt Result = Value.extOrTrunc(DestWidth);
2615 Result.setIsUnsigned(DestType->isUnsignedIntegerOrEnumerationType());
2616 if (DestType->isBooleanType())
2617 Result = Value.getBoolValue();
2618 return Result;
2619 }
2620
HandleIntToFloatCast(EvalInfo & Info,const Expr * E,const FPOptions FPO,QualType SrcType,const APSInt & Value,QualType DestType,APFloat & Result)2621 static bool HandleIntToFloatCast(EvalInfo &Info, const Expr *E,
2622 const FPOptions FPO,
2623 QualType SrcType, const APSInt &Value,
2624 QualType DestType, APFloat &Result) {
2625 Result = APFloat(Info.Ctx.getFloatTypeSemantics(DestType), 1);
2626 APFloat::opStatus St = Result.convertFromAPInt(Value, Value.isSigned(),
2627 APFloat::rmNearestTiesToEven);
2628 if (!Info.InConstantContext && St != llvm::APFloatBase::opOK &&
2629 FPO.isFPConstrained()) {
2630 Info.FFDiag(E, diag::note_constexpr_float_arithmetic_strict);
2631 return false;
2632 }
2633 return true;
2634 }
2635
truncateBitfieldValue(EvalInfo & Info,const Expr * E,APValue & Value,const FieldDecl * FD)2636 static bool truncateBitfieldValue(EvalInfo &Info, const Expr *E,
2637 APValue &Value, const FieldDecl *FD) {
2638 assert(FD->isBitField() && "truncateBitfieldValue on non-bitfield");
2639
2640 if (!Value.isInt()) {
2641 // Trying to store a pointer-cast-to-integer into a bitfield.
2642 // FIXME: In this case, we should provide the diagnostic for casting
2643 // a pointer to an integer.
2644 assert(Value.isLValue() && "integral value neither int nor lvalue?");
2645 Info.FFDiag(E);
2646 return false;
2647 }
2648
2649 APSInt &Int = Value.getInt();
2650 unsigned OldBitWidth = Int.getBitWidth();
2651 unsigned NewBitWidth = FD->getBitWidthValue(Info.Ctx);
2652 if (NewBitWidth < OldBitWidth)
2653 Int = Int.trunc(NewBitWidth).extend(OldBitWidth);
2654 return true;
2655 }
2656
EvalAndBitcastToAPInt(EvalInfo & Info,const Expr * E,llvm::APInt & Res)2657 static bool EvalAndBitcastToAPInt(EvalInfo &Info, const Expr *E,
2658 llvm::APInt &Res) {
2659 APValue SVal;
2660 if (!Evaluate(SVal, Info, E))
2661 return false;
2662 if (SVal.isInt()) {
2663 Res = SVal.getInt();
2664 return true;
2665 }
2666 if (SVal.isFloat()) {
2667 Res = SVal.getFloat().bitcastToAPInt();
2668 return true;
2669 }
2670 if (SVal.isVector()) {
2671 QualType VecTy = E->getType();
2672 unsigned VecSize = Info.Ctx.getTypeSize(VecTy);
2673 QualType EltTy = VecTy->castAs<VectorType>()->getElementType();
2674 unsigned EltSize = Info.Ctx.getTypeSize(EltTy);
2675 bool BigEndian = Info.Ctx.getTargetInfo().isBigEndian();
2676 Res = llvm::APInt::getNullValue(VecSize);
2677 for (unsigned i = 0; i < SVal.getVectorLength(); i++) {
2678 APValue &Elt = SVal.getVectorElt(i);
2679 llvm::APInt EltAsInt;
2680 if (Elt.isInt()) {
2681 EltAsInt = Elt.getInt();
2682 } else if (Elt.isFloat()) {
2683 EltAsInt = Elt.getFloat().bitcastToAPInt();
2684 } else {
2685 // Don't try to handle vectors of anything other than int or float
2686 // (not sure if it's possible to hit this case).
2687 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
2688 return false;
2689 }
2690 unsigned BaseEltSize = EltAsInt.getBitWidth();
2691 if (BigEndian)
2692 Res |= EltAsInt.zextOrTrunc(VecSize).rotr(i*EltSize+BaseEltSize);
2693 else
2694 Res |= EltAsInt.zextOrTrunc(VecSize).rotl(i*EltSize);
2695 }
2696 return true;
2697 }
2698 // Give up if the input isn't an int, float, or vector. For example, we
2699 // reject "(v4i16)(intptr_t)&a".
2700 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
2701 return false;
2702 }
2703
2704 /// Perform the given integer operation, which is known to need at most BitWidth
2705 /// bits, and check for overflow in the original type (if that type was not an
2706 /// unsigned type).
2707 template<typename Operation>
CheckedIntArithmetic(EvalInfo & Info,const Expr * E,const APSInt & LHS,const APSInt & RHS,unsigned BitWidth,Operation Op,APSInt & Result)2708 static bool CheckedIntArithmetic(EvalInfo &Info, const Expr *E,
2709 const APSInt &LHS, const APSInt &RHS,
2710 unsigned BitWidth, Operation Op,
2711 APSInt &Result) {
2712 if (LHS.isUnsigned()) {
2713 Result = Op(LHS, RHS);
2714 return true;
2715 }
2716
2717 APSInt Value(Op(LHS.extend(BitWidth), RHS.extend(BitWidth)), false);
2718 Result = Value.trunc(LHS.getBitWidth());
2719 if (Result.extend(BitWidth) != Value) {
2720 if (Info.checkingForUndefinedBehavior())
2721 Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
2722 diag::warn_integer_constant_overflow)
2723 << Result.toString(10) << E->getType();
2724 return HandleOverflow(Info, E, Value, E->getType());
2725 }
2726 return true;
2727 }
2728
2729 /// Perform the given binary integer operation.
handleIntIntBinOp(EvalInfo & Info,const Expr * E,const APSInt & LHS,BinaryOperatorKind Opcode,APSInt RHS,APSInt & Result)2730 static bool handleIntIntBinOp(EvalInfo &Info, const Expr *E, const APSInt &LHS,
2731 BinaryOperatorKind Opcode, APSInt RHS,
2732 APSInt &Result) {
2733 switch (Opcode) {
2734 default:
2735 Info.FFDiag(E);
2736 return false;
2737 case BO_Mul:
2738 return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() * 2,
2739 std::multiplies<APSInt>(), Result);
2740 case BO_Add:
2741 return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1,
2742 std::plus<APSInt>(), Result);
2743 case BO_Sub:
2744 return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1,
2745 std::minus<APSInt>(), Result);
2746 case BO_And: Result = LHS & RHS; return true;
2747 case BO_Xor: Result = LHS ^ RHS; return true;
2748 case BO_Or: Result = LHS | RHS; return true;
2749 case BO_Div:
2750 case BO_Rem:
2751 if (RHS == 0) {
2752 Info.FFDiag(E, diag::note_expr_divide_by_zero);
2753 return false;
2754 }
2755 Result = (Opcode == BO_Rem ? LHS % RHS : LHS / RHS);
2756 // Check for overflow case: INT_MIN / -1 or INT_MIN % -1. APSInt supports
2757 // this operation and gives the two's complement result.
2758 if (RHS.isNegative() && RHS.isAllOnesValue() &&
2759 LHS.isSigned() && LHS.isMinSignedValue())
2760 return HandleOverflow(Info, E, -LHS.extend(LHS.getBitWidth() + 1),
2761 E->getType());
2762 return true;
2763 case BO_Shl: {
2764 if (Info.getLangOpts().OpenCL)
2765 // OpenCL 6.3j: shift values are effectively % word size of LHS.
2766 RHS &= APSInt(llvm::APInt(RHS.getBitWidth(),
2767 static_cast<uint64_t>(LHS.getBitWidth() - 1)),
2768 RHS.isUnsigned());
2769 else if (RHS.isSigned() && RHS.isNegative()) {
2770 // During constant-folding, a negative shift is an opposite shift. Such
2771 // a shift is not a constant expression.
2772 Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHS;
2773 RHS = -RHS;
2774 goto shift_right;
2775 }
2776 shift_left:
2777 // C++11 [expr.shift]p1: Shift width must be less than the bit width of
2778 // the shifted type.
2779 unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1);
2780 if (SA != RHS) {
2781 Info.CCEDiag(E, diag::note_constexpr_large_shift)
2782 << RHS << E->getType() << LHS.getBitWidth();
2783 } else if (LHS.isSigned() && !Info.getLangOpts().CPlusPlus20) {
2784 // C++11 [expr.shift]p2: A signed left shift must have a non-negative
2785 // operand, and must not overflow the corresponding unsigned type.
2786 // C++2a [expr.shift]p2: E1 << E2 is the unique value congruent to
2787 // E1 x 2^E2 module 2^N.
2788 if (LHS.isNegative())
2789 Info.CCEDiag(E, diag::note_constexpr_lshift_of_negative) << LHS;
2790 else if (LHS.countLeadingZeros() < SA)
2791 Info.CCEDiag(E, diag::note_constexpr_lshift_discards);
2792 }
2793 Result = LHS << SA;
2794 return true;
2795 }
2796 case BO_Shr: {
2797 if (Info.getLangOpts().OpenCL)
2798 // OpenCL 6.3j: shift values are effectively % word size of LHS.
2799 RHS &= APSInt(llvm::APInt(RHS.getBitWidth(),
2800 static_cast<uint64_t>(LHS.getBitWidth() - 1)),
2801 RHS.isUnsigned());
2802 else if (RHS.isSigned() && RHS.isNegative()) {
2803 // During constant-folding, a negative shift is an opposite shift. Such a
2804 // shift is not a constant expression.
2805 Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHS;
2806 RHS = -RHS;
2807 goto shift_left;
2808 }
2809 shift_right:
2810 // C++11 [expr.shift]p1: Shift width must be less than the bit width of the
2811 // shifted type.
2812 unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1);
2813 if (SA != RHS)
2814 Info.CCEDiag(E, diag::note_constexpr_large_shift)
2815 << RHS << E->getType() << LHS.getBitWidth();
2816 Result = LHS >> SA;
2817 return true;
2818 }
2819
2820 case BO_LT: Result = LHS < RHS; return true;
2821 case BO_GT: Result = LHS > RHS; return true;
2822 case BO_LE: Result = LHS <= RHS; return true;
2823 case BO_GE: Result = LHS >= RHS; return true;
2824 case BO_EQ: Result = LHS == RHS; return true;
2825 case BO_NE: Result = LHS != RHS; return true;
2826 case BO_Cmp:
2827 llvm_unreachable("BO_Cmp should be handled elsewhere");
2828 }
2829 }
2830
2831 /// Perform the given binary floating-point operation, in-place, on LHS.
handleFloatFloatBinOp(EvalInfo & Info,const BinaryOperator * E,APFloat & LHS,BinaryOperatorKind Opcode,const APFloat & RHS)2832 static bool handleFloatFloatBinOp(EvalInfo &Info, const BinaryOperator *E,
2833 APFloat &LHS, BinaryOperatorKind Opcode,
2834 const APFloat &RHS) {
2835 bool DynamicRM;
2836 llvm::RoundingMode RM = getActiveRoundingMode(Info, E, DynamicRM);
2837 APFloat::opStatus St;
2838 switch (Opcode) {
2839 default:
2840 Info.FFDiag(E);
2841 return false;
2842 case BO_Mul:
2843 St = LHS.multiply(RHS, RM);
2844 break;
2845 case BO_Add:
2846 St = LHS.add(RHS, RM);
2847 break;
2848 case BO_Sub:
2849 St = LHS.subtract(RHS, RM);
2850 break;
2851 case BO_Div:
2852 // [expr.mul]p4:
2853 // If the second operand of / or % is zero the behavior is undefined.
2854 if (RHS.isZero())
2855 Info.CCEDiag(E, diag::note_expr_divide_by_zero);
2856 St = LHS.divide(RHS, RM);
2857 break;
2858 }
2859
2860 // [expr.pre]p4:
2861 // If during the evaluation of an expression, the result is not
2862 // mathematically defined [...], the behavior is undefined.
2863 // FIXME: C++ rules require us to not conform to IEEE 754 here.
2864 if (LHS.isNaN()) {
2865 Info.CCEDiag(E, diag::note_constexpr_float_arithmetic) << LHS.isNaN();
2866 return Info.noteUndefinedBehavior();
2867 }
2868
2869 return checkFloatingPointResult(Info, E, St);
2870 }
2871
handleLogicalOpForVector(const APInt & LHSValue,BinaryOperatorKind Opcode,const APInt & RHSValue,APInt & Result)2872 static bool handleLogicalOpForVector(const APInt &LHSValue,
2873 BinaryOperatorKind Opcode,
2874 const APInt &RHSValue, APInt &Result) {
2875 bool LHS = (LHSValue != 0);
2876 bool RHS = (RHSValue != 0);
2877
2878 if (Opcode == BO_LAnd)
2879 Result = LHS && RHS;
2880 else
2881 Result = LHS || RHS;
2882 return true;
2883 }
handleLogicalOpForVector(const APFloat & LHSValue,BinaryOperatorKind Opcode,const APFloat & RHSValue,APInt & Result)2884 static bool handleLogicalOpForVector(const APFloat &LHSValue,
2885 BinaryOperatorKind Opcode,
2886 const APFloat &RHSValue, APInt &Result) {
2887 bool LHS = !LHSValue.isZero();
2888 bool RHS = !RHSValue.isZero();
2889
2890 if (Opcode == BO_LAnd)
2891 Result = LHS && RHS;
2892 else
2893 Result = LHS || RHS;
2894 return true;
2895 }
2896
handleLogicalOpForVector(const APValue & LHSValue,BinaryOperatorKind Opcode,const APValue & RHSValue,APInt & Result)2897 static bool handleLogicalOpForVector(const APValue &LHSValue,
2898 BinaryOperatorKind Opcode,
2899 const APValue &RHSValue, APInt &Result) {
2900 // The result is always an int type, however operands match the first.
2901 if (LHSValue.getKind() == APValue::Int)
2902 return handleLogicalOpForVector(LHSValue.getInt(), Opcode,
2903 RHSValue.getInt(), Result);
2904 assert(LHSValue.getKind() == APValue::Float && "Should be no other options");
2905 return handleLogicalOpForVector(LHSValue.getFloat(), Opcode,
2906 RHSValue.getFloat(), Result);
2907 }
2908
2909 template <typename APTy>
2910 static bool
handleCompareOpForVectorHelper(const APTy & LHSValue,BinaryOperatorKind Opcode,const APTy & RHSValue,APInt & Result)2911 handleCompareOpForVectorHelper(const APTy &LHSValue, BinaryOperatorKind Opcode,
2912 const APTy &RHSValue, APInt &Result) {
2913 switch (Opcode) {
2914 default:
2915 llvm_unreachable("unsupported binary operator");
2916 case BO_EQ:
2917 Result = (LHSValue == RHSValue);
2918 break;
2919 case BO_NE:
2920 Result = (LHSValue != RHSValue);
2921 break;
2922 case BO_LT:
2923 Result = (LHSValue < RHSValue);
2924 break;
2925 case BO_GT:
2926 Result = (LHSValue > RHSValue);
2927 break;
2928 case BO_LE:
2929 Result = (LHSValue <= RHSValue);
2930 break;
2931 case BO_GE:
2932 Result = (LHSValue >= RHSValue);
2933 break;
2934 }
2935
2936 return true;
2937 }
2938
handleCompareOpForVector(const APValue & LHSValue,BinaryOperatorKind Opcode,const APValue & RHSValue,APInt & Result)2939 static bool handleCompareOpForVector(const APValue &LHSValue,
2940 BinaryOperatorKind Opcode,
2941 const APValue &RHSValue, APInt &Result) {
2942 // The result is always an int type, however operands match the first.
2943 if (LHSValue.getKind() == APValue::Int)
2944 return handleCompareOpForVectorHelper(LHSValue.getInt(), Opcode,
2945 RHSValue.getInt(), Result);
2946 assert(LHSValue.getKind() == APValue::Float && "Should be no other options");
2947 return handleCompareOpForVectorHelper(LHSValue.getFloat(), Opcode,
2948 RHSValue.getFloat(), Result);
2949 }
2950
2951 // Perform binary operations for vector types, in place on the LHS.
handleVectorVectorBinOp(EvalInfo & Info,const BinaryOperator * E,BinaryOperatorKind Opcode,APValue & LHSValue,const APValue & RHSValue)2952 static bool handleVectorVectorBinOp(EvalInfo &Info, const BinaryOperator *E,
2953 BinaryOperatorKind Opcode,
2954 APValue &LHSValue,
2955 const APValue &RHSValue) {
2956 assert(Opcode != BO_PtrMemD && Opcode != BO_PtrMemI &&
2957 "Operation not supported on vector types");
2958
2959 const auto *VT = E->getType()->castAs<VectorType>();
2960 unsigned NumElements = VT->getNumElements();
2961 QualType EltTy = VT->getElementType();
2962
2963 // In the cases (typically C as I've observed) where we aren't evaluating
2964 // constexpr but are checking for cases where the LHS isn't yet evaluatable,
2965 // just give up.
2966 if (!LHSValue.isVector()) {
2967 assert(LHSValue.isLValue() &&
2968 "A vector result that isn't a vector OR uncalculated LValue");
2969 Info.FFDiag(E);
2970 return false;
2971 }
2972
2973 assert(LHSValue.getVectorLength() == NumElements &&
2974 RHSValue.getVectorLength() == NumElements && "Different vector sizes");
2975
2976 SmallVector<APValue, 4> ResultElements;
2977
2978 for (unsigned EltNum = 0; EltNum < NumElements; ++EltNum) {
2979 APValue LHSElt = LHSValue.getVectorElt(EltNum);
2980 APValue RHSElt = RHSValue.getVectorElt(EltNum);
2981
2982 if (EltTy->isIntegerType()) {
2983 APSInt EltResult{Info.Ctx.getIntWidth(EltTy),
2984 EltTy->isUnsignedIntegerType()};
2985 bool Success = true;
2986
2987 if (BinaryOperator::isLogicalOp(Opcode))
2988 Success = handleLogicalOpForVector(LHSElt, Opcode, RHSElt, EltResult);
2989 else if (BinaryOperator::isComparisonOp(Opcode))
2990 Success = handleCompareOpForVector(LHSElt, Opcode, RHSElt, EltResult);
2991 else
2992 Success = handleIntIntBinOp(Info, E, LHSElt.getInt(), Opcode,
2993 RHSElt.getInt(), EltResult);
2994
2995 if (!Success) {
2996 Info.FFDiag(E);
2997 return false;
2998 }
2999 ResultElements.emplace_back(EltResult);
3000
3001 } else if (EltTy->isFloatingType()) {
3002 assert(LHSElt.getKind() == APValue::Float &&
3003 RHSElt.getKind() == APValue::Float &&
3004 "Mismatched LHS/RHS/Result Type");
3005 APFloat LHSFloat = LHSElt.getFloat();
3006
3007 if (!handleFloatFloatBinOp(Info, E, LHSFloat, Opcode,
3008 RHSElt.getFloat())) {
3009 Info.FFDiag(E);
3010 return false;
3011 }
3012
3013 ResultElements.emplace_back(LHSFloat);
3014 }
3015 }
3016
3017 LHSValue = APValue(ResultElements.data(), ResultElements.size());
3018 return true;
3019 }
3020
3021 /// Cast an lvalue referring to a base subobject to a derived class, by
3022 /// truncating the lvalue's path to the given length.
CastToDerivedClass(EvalInfo & Info,const Expr * E,LValue & Result,const RecordDecl * TruncatedType,unsigned TruncatedElements)3023 static bool CastToDerivedClass(EvalInfo &Info, const Expr *E, LValue &Result,
3024 const RecordDecl *TruncatedType,
3025 unsigned TruncatedElements) {
3026 SubobjectDesignator &D = Result.Designator;
3027
3028 // Check we actually point to a derived class object.
3029 if (TruncatedElements == D.Entries.size())
3030 return true;
3031 assert(TruncatedElements >= D.MostDerivedPathLength &&
3032 "not casting to a derived class");
3033 if (!Result.checkSubobject(Info, E, CSK_Derived))
3034 return false;
3035
3036 // Truncate the path to the subobject, and remove any derived-to-base offsets.
3037 const RecordDecl *RD = TruncatedType;
3038 for (unsigned I = TruncatedElements, N = D.Entries.size(); I != N; ++I) {
3039 if (RD->isInvalidDecl()) return false;
3040 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
3041 const CXXRecordDecl *Base = getAsBaseClass(D.Entries[I]);
3042 if (isVirtualBaseClass(D.Entries[I]))
3043 Result.Offset -= Layout.getVBaseClassOffset(Base);
3044 else
3045 Result.Offset -= Layout.getBaseClassOffset(Base);
3046 RD = Base;
3047 }
3048 D.Entries.resize(TruncatedElements);
3049 return true;
3050 }
3051
HandleLValueDirectBase(EvalInfo & Info,const Expr * E,LValue & Obj,const CXXRecordDecl * Derived,const CXXRecordDecl * Base,const ASTRecordLayout * RL=nullptr)3052 static bool HandleLValueDirectBase(EvalInfo &Info, const Expr *E, LValue &Obj,
3053 const CXXRecordDecl *Derived,
3054 const CXXRecordDecl *Base,
3055 const ASTRecordLayout *RL = nullptr) {
3056 if (!RL) {
3057 if (Derived->isInvalidDecl()) return false;
3058 RL = &Info.Ctx.getASTRecordLayout(Derived);
3059 }
3060
3061 Obj.getLValueOffset() += RL->getBaseClassOffset(Base);
3062 Obj.addDecl(Info, E, Base, /*Virtual*/ false);
3063 return true;
3064 }
3065
HandleLValueBase(EvalInfo & Info,const Expr * E,LValue & Obj,const CXXRecordDecl * DerivedDecl,const CXXBaseSpecifier * Base)3066 static bool HandleLValueBase(EvalInfo &Info, const Expr *E, LValue &Obj,
3067 const CXXRecordDecl *DerivedDecl,
3068 const CXXBaseSpecifier *Base) {
3069 const CXXRecordDecl *BaseDecl = Base->getType()->getAsCXXRecordDecl();
3070
3071 if (!Base->isVirtual())
3072 return HandleLValueDirectBase(Info, E, Obj, DerivedDecl, BaseDecl);
3073
3074 SubobjectDesignator &D = Obj.Designator;
3075 if (D.Invalid)
3076 return false;
3077
3078 // Extract most-derived object and corresponding type.
3079 DerivedDecl = D.MostDerivedType->getAsCXXRecordDecl();
3080 if (!CastToDerivedClass(Info, E, Obj, DerivedDecl, D.MostDerivedPathLength))
3081 return false;
3082
3083 // Find the virtual base class.
3084 if (DerivedDecl->isInvalidDecl()) return false;
3085 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(DerivedDecl);
3086 Obj.getLValueOffset() += Layout.getVBaseClassOffset(BaseDecl);
3087 Obj.addDecl(Info, E, BaseDecl, /*Virtual*/ true);
3088 return true;
3089 }
3090
HandleLValueBasePath(EvalInfo & Info,const CastExpr * E,QualType Type,LValue & Result)3091 static bool HandleLValueBasePath(EvalInfo &Info, const CastExpr *E,
3092 QualType Type, LValue &Result) {
3093 for (CastExpr::path_const_iterator PathI = E->path_begin(),
3094 PathE = E->path_end();
3095 PathI != PathE; ++PathI) {
3096 if (!HandleLValueBase(Info, E, Result, Type->getAsCXXRecordDecl(),
3097 *PathI))
3098 return false;
3099 Type = (*PathI)->getType();
3100 }
3101 return true;
3102 }
3103
3104 /// 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)3105 static bool CastToBaseClass(EvalInfo &Info, const Expr *E, LValue &Result,
3106 const CXXRecordDecl *DerivedRD,
3107 const CXXRecordDecl *BaseRD) {
3108 CXXBasePaths Paths(/*FindAmbiguities=*/false,
3109 /*RecordPaths=*/true, /*DetectVirtual=*/false);
3110 if (!DerivedRD->isDerivedFrom(BaseRD, Paths))
3111 llvm_unreachable("Class must be derived from the passed in base class!");
3112
3113 for (CXXBasePathElement &Elem : Paths.front())
3114 if (!HandleLValueBase(Info, E, Result, Elem.Class, Elem.Base))
3115 return false;
3116 return true;
3117 }
3118
3119 /// Update LVal to refer to the given field, which must be a member of the type
3120 /// currently described by LVal.
HandleLValueMember(EvalInfo & Info,const Expr * E,LValue & LVal,const FieldDecl * FD,const ASTRecordLayout * RL=nullptr)3121 static bool HandleLValueMember(EvalInfo &Info, const Expr *E, LValue &LVal,
3122 const FieldDecl *FD,
3123 const ASTRecordLayout *RL = nullptr) {
3124 if (!RL) {
3125 if (FD->getParent()->isInvalidDecl()) return false;
3126 RL = &Info.Ctx.getASTRecordLayout(FD->getParent());
3127 }
3128
3129 unsigned I = FD->getFieldIndex();
3130 LVal.adjustOffset(Info.Ctx.toCharUnitsFromBits(RL->getFieldOffset(I)));
3131 LVal.addDecl(Info, E, FD);
3132 return true;
3133 }
3134
3135 /// Update LVal to refer to the given indirect field.
HandleLValueIndirectMember(EvalInfo & Info,const Expr * E,LValue & LVal,const IndirectFieldDecl * IFD)3136 static bool HandleLValueIndirectMember(EvalInfo &Info, const Expr *E,
3137 LValue &LVal,
3138 const IndirectFieldDecl *IFD) {
3139 for (const auto *C : IFD->chain())
3140 if (!HandleLValueMember(Info, E, LVal, cast<FieldDecl>(C)))
3141 return false;
3142 return true;
3143 }
3144
3145 /// Get the size of the given type in char units.
HandleSizeof(EvalInfo & Info,SourceLocation Loc,QualType Type,CharUnits & Size)3146 static bool HandleSizeof(EvalInfo &Info, SourceLocation Loc,
3147 QualType Type, CharUnits &Size) {
3148 // sizeof(void), __alignof__(void), sizeof(function) = 1 as a gcc
3149 // extension.
3150 if (Type->isVoidType() || Type->isFunctionType()) {
3151 Size = CharUnits::One();
3152 return true;
3153 }
3154
3155 if (Type->isDependentType()) {
3156 Info.FFDiag(Loc);
3157 return false;
3158 }
3159
3160 if (!Type->isConstantSizeType()) {
3161 // sizeof(vla) is not a constantexpr: C99 6.5.3.4p2.
3162 // FIXME: Better diagnostic.
3163 Info.FFDiag(Loc);
3164 return false;
3165 }
3166
3167 Size = Info.Ctx.getTypeSizeInChars(Type);
3168 return true;
3169 }
3170
3171 /// Update a pointer value to model pointer arithmetic.
3172 /// \param Info - Information about the ongoing evaluation.
3173 /// \param E - The expression being evaluated, for diagnostic purposes.
3174 /// \param LVal - The pointer value to be updated.
3175 /// \param EltTy - The pointee type represented by LVal.
3176 /// \param Adjustment - The adjustment, in objects of type EltTy, to add.
HandleLValueArrayAdjustment(EvalInfo & Info,const Expr * E,LValue & LVal,QualType EltTy,APSInt Adjustment)3177 static bool HandleLValueArrayAdjustment(EvalInfo &Info, const Expr *E,
3178 LValue &LVal, QualType EltTy,
3179 APSInt Adjustment) {
3180 CharUnits SizeOfPointee;
3181 if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfPointee))
3182 return false;
3183
3184 LVal.adjustOffsetAndIndex(Info, E, Adjustment, SizeOfPointee);
3185 return true;
3186 }
3187
HandleLValueArrayAdjustment(EvalInfo & Info,const Expr * E,LValue & LVal,QualType EltTy,int64_t Adjustment)3188 static bool HandleLValueArrayAdjustment(EvalInfo &Info, const Expr *E,
3189 LValue &LVal, QualType EltTy,
3190 int64_t Adjustment) {
3191 return HandleLValueArrayAdjustment(Info, E, LVal, EltTy,
3192 APSInt::get(Adjustment));
3193 }
3194
3195 /// Update an lvalue to refer to a component of a complex number.
3196 /// \param Info - Information about the ongoing evaluation.
3197 /// \param LVal - The lvalue to be updated.
3198 /// \param EltTy - The complex number's component type.
3199 /// \param Imag - False for the real component, true for the imaginary.
HandleLValueComplexElement(EvalInfo & Info,const Expr * E,LValue & LVal,QualType EltTy,bool Imag)3200 static bool HandleLValueComplexElement(EvalInfo &Info, const Expr *E,
3201 LValue &LVal, QualType EltTy,
3202 bool Imag) {
3203 if (Imag) {
3204 CharUnits SizeOfComponent;
3205 if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfComponent))
3206 return false;
3207 LVal.Offset += SizeOfComponent;
3208 }
3209 LVal.addComplex(Info, E, EltTy, Imag);
3210 return true;
3211 }
3212
3213 /// Try to evaluate the initializer for a variable declaration.
3214 ///
3215 /// \param Info Information about the ongoing evaluation.
3216 /// \param E An expression to be used when printing diagnostics.
3217 /// \param VD The variable whose initializer should be obtained.
3218 /// \param Version The version of the variable within the frame.
3219 /// \param Frame The frame in which the variable was created. Must be null
3220 /// if this variable is not local to the evaluation.
3221 /// \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)3222 static bool evaluateVarDeclInit(EvalInfo &Info, const Expr *E,
3223 const VarDecl *VD, CallStackFrame *Frame,
3224 unsigned Version, APValue *&Result) {
3225 APValue::LValueBase Base(VD, Frame ? Frame->Index : 0, Version);
3226
3227 // If this is a local variable, dig out its value.
3228 if (Frame) {
3229 Result = Frame->getTemporary(VD, Version);
3230 if (Result)
3231 return true;
3232
3233 if (!isa<ParmVarDecl>(VD)) {
3234 // Assume variables referenced within a lambda's call operator that were
3235 // not declared within the call operator are captures and during checking
3236 // of a potential constant expression, assume they are unknown constant
3237 // expressions.
3238 assert(isLambdaCallOperator(Frame->Callee) &&
3239 (VD->getDeclContext() != Frame->Callee || VD->isInitCapture()) &&
3240 "missing value for local variable");
3241 if (Info.checkingPotentialConstantExpression())
3242 return false;
3243 // FIXME: This diagnostic is bogus; we do support captures. Is this code
3244 // still reachable at all?
3245 Info.FFDiag(E->getBeginLoc(),
3246 diag::note_unimplemented_constexpr_lambda_feature_ast)
3247 << "captures not currently allowed";
3248 return false;
3249 }
3250 }
3251
3252 // If we're currently evaluating the initializer of this declaration, use that
3253 // in-flight value.
3254 if (Info.EvaluatingDecl == Base) {
3255 Result = Info.EvaluatingDeclValue;
3256 return true;
3257 }
3258
3259 if (isa<ParmVarDecl>(VD)) {
3260 // Assume parameters of a potential constant expression are usable in
3261 // constant expressions.
3262 if (!Info.checkingPotentialConstantExpression() ||
3263 !Info.CurrentCall->Callee ||
3264 !Info.CurrentCall->Callee->Equals(VD->getDeclContext())) {
3265 if (Info.getLangOpts().CPlusPlus11) {
3266 Info.FFDiag(E, diag::note_constexpr_function_param_value_unknown)
3267 << VD;
3268 NoteLValueLocation(Info, Base);
3269 } else {
3270 Info.FFDiag(E);
3271 }
3272 }
3273 return false;
3274 }
3275
3276 // Dig out the initializer, and use the declaration which it's attached to.
3277 // FIXME: We should eventually check whether the variable has a reachable
3278 // initializing declaration.
3279 const Expr *Init = VD->getAnyInitializer(VD);
3280 if (!Init) {
3281 // Don't diagnose during potential constant expression checking; an
3282 // initializer might be added later.
3283 if (!Info.checkingPotentialConstantExpression()) {
3284 Info.FFDiag(E, diag::note_constexpr_var_init_unknown, 1)
3285 << VD;
3286 NoteLValueLocation(Info, Base);
3287 }
3288 return false;
3289 }
3290
3291 if (Init->isValueDependent()) {
3292 // The DeclRefExpr is not value-dependent, but the variable it refers to
3293 // has a value-dependent initializer. This should only happen in
3294 // constant-folding cases, where the variable is not actually of a suitable
3295 // type for use in a constant expression (otherwise the DeclRefExpr would
3296 // have been value-dependent too), so diagnose that.
3297 assert(!VD->mightBeUsableInConstantExpressions(Info.Ctx));
3298 if (!Info.checkingPotentialConstantExpression()) {
3299 Info.FFDiag(E, Info.getLangOpts().CPlusPlus11
3300 ? diag::note_constexpr_ltor_non_constexpr
3301 : diag::note_constexpr_ltor_non_integral, 1)
3302 << VD << VD->getType();
3303 NoteLValueLocation(Info, Base);
3304 }
3305 return false;
3306 }
3307
3308 // Check that we can fold the initializer. In C++, we will have already done
3309 // this in the cases where it matters for conformance.
3310 if (!VD->evaluateValue()) {
3311 Info.FFDiag(E, diag::note_constexpr_var_init_non_constant, 1) << VD;
3312 NoteLValueLocation(Info, Base);
3313 return false;
3314 }
3315
3316 // Check that the variable is actually usable in constant expressions. For a
3317 // const integral variable or a reference, we might have a non-constant
3318 // initializer that we can nonetheless evaluate the initializer for. Such
3319 // variables are not usable in constant expressions. In C++98, the
3320 // initializer also syntactically needs to be an ICE.
3321 //
3322 // FIXME: We don't diagnose cases that aren't potentially usable in constant
3323 // expressions here; doing so would regress diagnostics for things like
3324 // reading from a volatile constexpr variable.
3325 if ((Info.getLangOpts().CPlusPlus && !VD->hasConstantInitialization() &&
3326 VD->mightBeUsableInConstantExpressions(Info.Ctx)) ||
3327 ((Info.getLangOpts().CPlusPlus || Info.getLangOpts().OpenCL) &&
3328 !Info.getLangOpts().CPlusPlus11 && !VD->hasICEInitializer(Info.Ctx))) {
3329 Info.CCEDiag(E, diag::note_constexpr_var_init_non_constant, 1) << VD;
3330 NoteLValueLocation(Info, Base);
3331 }
3332
3333 // Never use the initializer of a weak variable, not even for constant
3334 // folding. We can't be sure that this is the definition that will be used.
3335 if (VD->isWeak()) {
3336 Info.FFDiag(E, diag::note_constexpr_var_init_weak) << VD;
3337 NoteLValueLocation(Info, Base);
3338 return false;
3339 }
3340
3341 Result = VD->getEvaluatedValue();
3342 return true;
3343 }
3344
3345 /// Get the base index of the given base class within an APValue representing
3346 /// the given derived class.
getBaseIndex(const CXXRecordDecl * Derived,const CXXRecordDecl * Base)3347 static unsigned getBaseIndex(const CXXRecordDecl *Derived,
3348 const CXXRecordDecl *Base) {
3349 Base = Base->getCanonicalDecl();
3350 unsigned Index = 0;
3351 for (CXXRecordDecl::base_class_const_iterator I = Derived->bases_begin(),
3352 E = Derived->bases_end(); I != E; ++I, ++Index) {
3353 if (I->getType()->getAsCXXRecordDecl()->getCanonicalDecl() == Base)
3354 return Index;
3355 }
3356
3357 llvm_unreachable("base class missing from derived class's bases list");
3358 }
3359
3360 /// Extract the value of a character from a string literal.
extractStringLiteralCharacter(EvalInfo & Info,const Expr * Lit,uint64_t Index)3361 static APSInt extractStringLiteralCharacter(EvalInfo &Info, const Expr *Lit,
3362 uint64_t Index) {
3363 assert(!isa<SourceLocExpr>(Lit) &&
3364 "SourceLocExpr should have already been converted to a StringLiteral");
3365
3366 // FIXME: Support MakeStringConstant
3367 if (const auto *ObjCEnc = dyn_cast<ObjCEncodeExpr>(Lit)) {
3368 std::string Str;
3369 Info.Ctx.getObjCEncodingForType(ObjCEnc->getEncodedType(), Str);
3370 assert(Index <= Str.size() && "Index too large");
3371 return APSInt::getUnsigned(Str.c_str()[Index]);
3372 }
3373
3374 if (auto PE = dyn_cast<PredefinedExpr>(Lit))
3375 Lit = PE->getFunctionName();
3376 const StringLiteral *S = cast<StringLiteral>(Lit);
3377 const ConstantArrayType *CAT =
3378 Info.Ctx.getAsConstantArrayType(S->getType());
3379 assert(CAT && "string literal isn't an array");
3380 QualType CharType = CAT->getElementType();
3381 assert(CharType->isIntegerType() && "unexpected character type");
3382
3383 APSInt Value(S->getCharByteWidth() * Info.Ctx.getCharWidth(),
3384 CharType->isUnsignedIntegerType());
3385 if (Index < S->getLength())
3386 Value = S->getCodeUnit(Index);
3387 return Value;
3388 }
3389
3390 // Expand a string literal into an array of characters.
3391 //
3392 // FIXME: This is inefficient; we should probably introduce something similar
3393 // to the LLVM ConstantDataArray to make this cheaper.
expandStringLiteral(EvalInfo & Info,const StringLiteral * S,APValue & Result,QualType AllocType=QualType ())3394 static void expandStringLiteral(EvalInfo &Info, const StringLiteral *S,
3395 APValue &Result,
3396 QualType AllocType = QualType()) {
3397 const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(
3398 AllocType.isNull() ? S->getType() : AllocType);
3399 assert(CAT && "string literal isn't an array");
3400 QualType CharType = CAT->getElementType();
3401 assert(CharType->isIntegerType() && "unexpected character type");
3402
3403 unsigned Elts = CAT->getSize().getZExtValue();
3404 Result = APValue(APValue::UninitArray(),
3405 std::min(S->getLength(), Elts), Elts);
3406 APSInt Value(S->getCharByteWidth() * Info.Ctx.getCharWidth(),
3407 CharType->isUnsignedIntegerType());
3408 if (Result.hasArrayFiller())
3409 Result.getArrayFiller() = APValue(Value);
3410 for (unsigned I = 0, N = Result.getArrayInitializedElts(); I != N; ++I) {
3411 Value = S->getCodeUnit(I);
3412 Result.getArrayInitializedElt(I) = APValue(Value);
3413 }
3414 }
3415
3416 // Expand an array so that it has more than Index filled elements.
expandArray(APValue & Array,unsigned Index)3417 static void expandArray(APValue &Array, unsigned Index) {
3418 unsigned Size = Array.getArraySize();
3419 assert(Index < Size);
3420
3421 // Always at least double the number of elements for which we store a value.
3422 unsigned OldElts = Array.getArrayInitializedElts();
3423 unsigned NewElts = std::max(Index+1, OldElts * 2);
3424 NewElts = std::min(Size, std::max(NewElts, 8u));
3425
3426 // Copy the data across.
3427 APValue NewValue(APValue::UninitArray(), NewElts, Size);
3428 for (unsigned I = 0; I != OldElts; ++I)
3429 NewValue.getArrayInitializedElt(I).swap(Array.getArrayInitializedElt(I));
3430 for (unsigned I = OldElts; I != NewElts; ++I)
3431 NewValue.getArrayInitializedElt(I) = Array.getArrayFiller();
3432 if (NewValue.hasArrayFiller())
3433 NewValue.getArrayFiller() = Array.getArrayFiller();
3434 Array.swap(NewValue);
3435 }
3436
3437 /// Determine whether a type would actually be read by an lvalue-to-rvalue
3438 /// conversion. If it's of class type, we may assume that the copy operation
3439 /// is trivial. Note that this is never true for a union type with fields
3440 /// (because the copy always "reads" the active member) and always true for
3441 /// a non-class type.
3442 static bool isReadByLvalueToRvalueConversion(const CXXRecordDecl *RD);
isReadByLvalueToRvalueConversion(QualType T)3443 static bool isReadByLvalueToRvalueConversion(QualType T) {
3444 CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
3445 return !RD || isReadByLvalueToRvalueConversion(RD);
3446 }
isReadByLvalueToRvalueConversion(const CXXRecordDecl * RD)3447 static bool isReadByLvalueToRvalueConversion(const CXXRecordDecl *RD) {
3448 // FIXME: A trivial copy of a union copies the object representation, even if
3449 // the union is empty.
3450 if (RD->isUnion())
3451 return !RD->field_empty();
3452 if (RD->isEmpty())
3453 return false;
3454
3455 for (auto *Field : RD->fields())
3456 if (!Field->isUnnamedBitfield() &&
3457 isReadByLvalueToRvalueConversion(Field->getType()))
3458 return true;
3459
3460 for (auto &BaseSpec : RD->bases())
3461 if (isReadByLvalueToRvalueConversion(BaseSpec.getType()))
3462 return true;
3463
3464 return false;
3465 }
3466
3467 /// Diagnose an attempt to read from any unreadable field within the specified
3468 /// type, which might be a class type.
diagnoseMutableFields(EvalInfo & Info,const Expr * E,AccessKinds AK,QualType T)3469 static bool diagnoseMutableFields(EvalInfo &Info, const Expr *E, AccessKinds AK,
3470 QualType T) {
3471 CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
3472 if (!RD)
3473 return false;
3474
3475 if (!RD->hasMutableFields())
3476 return false;
3477
3478 for (auto *Field : RD->fields()) {
3479 // If we're actually going to read this field in some way, then it can't
3480 // be mutable. If we're in a union, then assigning to a mutable field
3481 // (even an empty one) can change the active member, so that's not OK.
3482 // FIXME: Add core issue number for the union case.
3483 if (Field->isMutable() &&
3484 (RD->isUnion() || isReadByLvalueToRvalueConversion(Field->getType()))) {
3485 Info.FFDiag(E, diag::note_constexpr_access_mutable, 1) << AK << Field;
3486 Info.Note(Field->getLocation(), diag::note_declared_at);
3487 return true;
3488 }
3489
3490 if (diagnoseMutableFields(Info, E, AK, Field->getType()))
3491 return true;
3492 }
3493
3494 for (auto &BaseSpec : RD->bases())
3495 if (diagnoseMutableFields(Info, E, AK, BaseSpec.getType()))
3496 return true;
3497
3498 // All mutable fields were empty, and thus not actually read.
3499 return false;
3500 }
3501
lifetimeStartedInEvaluation(EvalInfo & Info,APValue::LValueBase Base,bool MutableSubobject=false)3502 static bool lifetimeStartedInEvaluation(EvalInfo &Info,
3503 APValue::LValueBase Base,
3504 bool MutableSubobject = false) {
3505 // A temporary or transient heap allocation we created.
3506 if (Base.getCallIndex() || Base.is<DynamicAllocLValue>())
3507 return true;
3508
3509 switch (Info.IsEvaluatingDecl) {
3510 case EvalInfo::EvaluatingDeclKind::None:
3511 return false;
3512
3513 case EvalInfo::EvaluatingDeclKind::Ctor:
3514 // The variable whose initializer we're evaluating.
3515 if (Info.EvaluatingDecl == Base)
3516 return true;
3517
3518 // A temporary lifetime-extended by the variable whose initializer we're
3519 // evaluating.
3520 if (auto *BaseE = Base.dyn_cast<const Expr *>())
3521 if (auto *BaseMTE = dyn_cast<MaterializeTemporaryExpr>(BaseE))
3522 return Info.EvaluatingDecl == BaseMTE->getExtendingDecl();
3523 return false;
3524
3525 case EvalInfo::EvaluatingDeclKind::Dtor:
3526 // C++2a [expr.const]p6:
3527 // [during constant destruction] the lifetime of a and its non-mutable
3528 // subobjects (but not its mutable subobjects) [are] considered to start
3529 // within e.
3530 if (MutableSubobject || Base != Info.EvaluatingDecl)
3531 return false;
3532 // FIXME: We can meaningfully extend this to cover non-const objects, but
3533 // we will need special handling: we should be able to access only
3534 // subobjects of such objects that are themselves declared const.
3535 QualType T = getType(Base);
3536 return T.isConstQualified() || T->isReferenceType();
3537 }
3538
3539 llvm_unreachable("unknown evaluating decl kind");
3540 }
3541
3542 namespace {
3543 /// A handle to a complete object (an object that is not a subobject of
3544 /// another object).
3545 struct CompleteObject {
3546 /// The identity of the object.
3547 APValue::LValueBase Base;
3548 /// The value of the complete object.
3549 APValue *Value;
3550 /// The type of the complete object.
3551 QualType Type;
3552
CompleteObject__anon6b379bbb0911::CompleteObject3553 CompleteObject() : Value(nullptr) {}
CompleteObject__anon6b379bbb0911::CompleteObject3554 CompleteObject(APValue::LValueBase Base, APValue *Value, QualType Type)
3555 : Base(Base), Value(Value), Type(Type) {}
3556
mayAccessMutableMembers__anon6b379bbb0911::CompleteObject3557 bool mayAccessMutableMembers(EvalInfo &Info, AccessKinds AK) const {
3558 // If this isn't a "real" access (eg, if it's just accessing the type
3559 // info), allow it. We assume the type doesn't change dynamically for
3560 // subobjects of constexpr objects (even though we'd hit UB here if it
3561 // did). FIXME: Is this right?
3562 if (!isAnyAccess(AK))
3563 return true;
3564
3565 // In C++14 onwards, it is permitted to read a mutable member whose
3566 // lifetime began within the evaluation.
3567 // FIXME: Should we also allow this in C++11?
3568 if (!Info.getLangOpts().CPlusPlus14)
3569 return false;
3570 return lifetimeStartedInEvaluation(Info, Base, /*MutableSubobject*/true);
3571 }
3572
operator bool__anon6b379bbb0911::CompleteObject3573 explicit operator bool() const { return !Type.isNull(); }
3574 };
3575 } // end anonymous namespace
3576
getSubobjectType(QualType ObjType,QualType SubobjType,bool IsMutable=false)3577 static QualType getSubobjectType(QualType ObjType, QualType SubobjType,
3578 bool IsMutable = false) {
3579 // C++ [basic.type.qualifier]p1:
3580 // - A const object is an object of type const T or a non-mutable subobject
3581 // of a const object.
3582 if (ObjType.isConstQualified() && !IsMutable)
3583 SubobjType.addConst();
3584 // - A volatile object is an object of type const T or a subobject of a
3585 // volatile object.
3586 if (ObjType.isVolatileQualified())
3587 SubobjType.addVolatile();
3588 return SubobjType;
3589 }
3590
3591 /// Find the designated sub-object of an rvalue.
3592 template<typename SubobjectHandler>
3593 typename SubobjectHandler::result_type
findSubobject(EvalInfo & Info,const Expr * E,const CompleteObject & Obj,const SubobjectDesignator & Sub,SubobjectHandler & handler)3594 findSubobject(EvalInfo &Info, const Expr *E, const CompleteObject &Obj,
3595 const SubobjectDesignator &Sub, SubobjectHandler &handler) {
3596 if (Sub.Invalid)
3597 // A diagnostic will have already been produced.
3598 return handler.failed();
3599 if (Sub.isOnePastTheEnd() || Sub.isMostDerivedAnUnsizedArray()) {
3600 if (Info.getLangOpts().CPlusPlus11)
3601 Info.FFDiag(E, Sub.isOnePastTheEnd()
3602 ? diag::note_constexpr_access_past_end
3603 : diag::note_constexpr_access_unsized_array)
3604 << handler.AccessKind;
3605 else
3606 Info.FFDiag(E);
3607 return handler.failed();
3608 }
3609
3610 APValue *O = Obj.Value;
3611 QualType ObjType = Obj.Type;
3612 const FieldDecl *LastField = nullptr;
3613 const FieldDecl *VolatileField = nullptr;
3614
3615 // Walk the designator's path to find the subobject.
3616 for (unsigned I = 0, N = Sub.Entries.size(); /**/; ++I) {
3617 // Reading an indeterminate value is undefined, but assigning over one is OK.
3618 if ((O->isAbsent() && !(handler.AccessKind == AK_Construct && I == N)) ||
3619 (O->isIndeterminate() &&
3620 !isValidIndeterminateAccess(handler.AccessKind))) {
3621 if (!Info.checkingPotentialConstantExpression())
3622 Info.FFDiag(E, diag::note_constexpr_access_uninit)
3623 << handler.AccessKind << O->isIndeterminate();
3624 return handler.failed();
3625 }
3626
3627 // C++ [class.ctor]p5, C++ [class.dtor]p5:
3628 // const and volatile semantics are not applied on an object under
3629 // {con,de}struction.
3630 if ((ObjType.isConstQualified() || ObjType.isVolatileQualified()) &&
3631 ObjType->isRecordType() &&
3632 Info.isEvaluatingCtorDtor(
3633 Obj.Base, llvm::makeArrayRef(Sub.Entries.begin(),
3634 Sub.Entries.begin() + I)) !=
3635 ConstructionPhase::None) {
3636 ObjType = Info.Ctx.getCanonicalType(ObjType);
3637 ObjType.removeLocalConst();
3638 ObjType.removeLocalVolatile();
3639 }
3640
3641 // If this is our last pass, check that the final object type is OK.
3642 if (I == N || (I == N - 1 && ObjType->isAnyComplexType())) {
3643 // Accesses to volatile objects are prohibited.
3644 if (ObjType.isVolatileQualified() && isFormalAccess(handler.AccessKind)) {
3645 if (Info.getLangOpts().CPlusPlus) {
3646 int DiagKind;
3647 SourceLocation Loc;
3648 const NamedDecl *Decl = nullptr;
3649 if (VolatileField) {
3650 DiagKind = 2;
3651 Loc = VolatileField->getLocation();
3652 Decl = VolatileField;
3653 } else if (auto *VD = Obj.Base.dyn_cast<const ValueDecl*>()) {
3654 DiagKind = 1;
3655 Loc = VD->getLocation();
3656 Decl = VD;
3657 } else {
3658 DiagKind = 0;
3659 if (auto *E = Obj.Base.dyn_cast<const Expr *>())
3660 Loc = E->getExprLoc();
3661 }
3662 Info.FFDiag(E, diag::note_constexpr_access_volatile_obj, 1)
3663 << handler.AccessKind << DiagKind << Decl;
3664 Info.Note(Loc, diag::note_constexpr_volatile_here) << DiagKind;
3665 } else {
3666 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
3667 }
3668 return handler.failed();
3669 }
3670
3671 // If we are reading an object of class type, there may still be more
3672 // things we need to check: if there are any mutable subobjects, we
3673 // cannot perform this read. (This only happens when performing a trivial
3674 // copy or assignment.)
3675 if (ObjType->isRecordType() &&
3676 !Obj.mayAccessMutableMembers(Info, handler.AccessKind) &&
3677 diagnoseMutableFields(Info, E, handler.AccessKind, ObjType))
3678 return handler.failed();
3679 }
3680
3681 if (I == N) {
3682 if (!handler.found(*O, ObjType))
3683 return false;
3684
3685 // If we modified a bit-field, truncate it to the right width.
3686 if (isModification(handler.AccessKind) &&
3687 LastField && LastField->isBitField() &&
3688 !truncateBitfieldValue(Info, E, *O, LastField))
3689 return false;
3690
3691 return true;
3692 }
3693
3694 LastField = nullptr;
3695 if (ObjType->isArrayType()) {
3696 // Next subobject is an array element.
3697 const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(ObjType);
3698 assert(CAT && "vla in literal type?");
3699 uint64_t Index = Sub.Entries[I].getAsArrayIndex();
3700 if (CAT->getSize().ule(Index)) {
3701 // Note, it should not be possible to form a pointer with a valid
3702 // designator which points more than one past the end of the array.
3703 if (Info.getLangOpts().CPlusPlus11)
3704 Info.FFDiag(E, diag::note_constexpr_access_past_end)
3705 << handler.AccessKind;
3706 else
3707 Info.FFDiag(E);
3708 return handler.failed();
3709 }
3710
3711 ObjType = CAT->getElementType();
3712
3713 if (O->getArrayInitializedElts() > Index)
3714 O = &O->getArrayInitializedElt(Index);
3715 else if (!isRead(handler.AccessKind)) {
3716 expandArray(*O, Index);
3717 O = &O->getArrayInitializedElt(Index);
3718 } else
3719 O = &O->getArrayFiller();
3720 } else if (ObjType->isAnyComplexType()) {
3721 // Next subobject is a complex number.
3722 uint64_t Index = Sub.Entries[I].getAsArrayIndex();
3723 if (Index > 1) {
3724 if (Info.getLangOpts().CPlusPlus11)
3725 Info.FFDiag(E, diag::note_constexpr_access_past_end)
3726 << handler.AccessKind;
3727 else
3728 Info.FFDiag(E);
3729 return handler.failed();
3730 }
3731
3732 ObjType = getSubobjectType(
3733 ObjType, ObjType->castAs<ComplexType>()->getElementType());
3734
3735 assert(I == N - 1 && "extracting subobject of scalar?");
3736 if (O->isComplexInt()) {
3737 return handler.found(Index ? O->getComplexIntImag()
3738 : O->getComplexIntReal(), ObjType);
3739 } else {
3740 assert(O->isComplexFloat());
3741 return handler.found(Index ? O->getComplexFloatImag()
3742 : O->getComplexFloatReal(), ObjType);
3743 }
3744 } else if (const FieldDecl *Field = getAsField(Sub.Entries[I])) {
3745 if (Field->isMutable() &&
3746 !Obj.mayAccessMutableMembers(Info, handler.AccessKind)) {
3747 Info.FFDiag(E, diag::note_constexpr_access_mutable, 1)
3748 << handler.AccessKind << Field;
3749 Info.Note(Field->getLocation(), diag::note_declared_at);
3750 return handler.failed();
3751 }
3752
3753 // Next subobject is a class, struct or union field.
3754 RecordDecl *RD = ObjType->castAs<RecordType>()->getDecl();
3755 if (RD->isUnion()) {
3756 const FieldDecl *UnionField = O->getUnionField();
3757 if (!UnionField ||
3758 UnionField->getCanonicalDecl() != Field->getCanonicalDecl()) {
3759 if (I == N - 1 && handler.AccessKind == AK_Construct) {
3760 // Placement new onto an inactive union member makes it active.
3761 O->setUnion(Field, APValue());
3762 } else {
3763 // FIXME: If O->getUnionValue() is absent, report that there's no
3764 // active union member rather than reporting the prior active union
3765 // member. We'll need to fix nullptr_t to not use APValue() as its
3766 // representation first.
3767 Info.FFDiag(E, diag::note_constexpr_access_inactive_union_member)
3768 << handler.AccessKind << Field << !UnionField << UnionField;
3769 return handler.failed();
3770 }
3771 }
3772 O = &O->getUnionValue();
3773 } else
3774 O = &O->getStructField(Field->getFieldIndex());
3775
3776 ObjType = getSubobjectType(ObjType, Field->getType(), Field->isMutable());
3777 LastField = Field;
3778 if (Field->getType().isVolatileQualified())
3779 VolatileField = Field;
3780 } else {
3781 // Next subobject is a base class.
3782 const CXXRecordDecl *Derived = ObjType->getAsCXXRecordDecl();
3783 const CXXRecordDecl *Base = getAsBaseClass(Sub.Entries[I]);
3784 O = &O->getStructBase(getBaseIndex(Derived, Base));
3785
3786 ObjType = getSubobjectType(ObjType, Info.Ctx.getRecordType(Base));
3787 }
3788 }
3789 }
3790
3791 namespace {
3792 struct ExtractSubobjectHandler {
3793 EvalInfo &Info;
3794 const Expr *E;
3795 APValue &Result;
3796 const AccessKinds AccessKind;
3797
3798 typedef bool result_type;
failed__anon6b379bbb0a11::ExtractSubobjectHandler3799 bool failed() { return false; }
found__anon6b379bbb0a11::ExtractSubobjectHandler3800 bool found(APValue &Subobj, QualType SubobjType) {
3801 Result = Subobj;
3802 if (AccessKind == AK_ReadObjectRepresentation)
3803 return true;
3804 return CheckFullyInitialized(Info, E->getExprLoc(), SubobjType, Result);
3805 }
found__anon6b379bbb0a11::ExtractSubobjectHandler3806 bool found(APSInt &Value, QualType SubobjType) {
3807 Result = APValue(Value);
3808 return true;
3809 }
found__anon6b379bbb0a11::ExtractSubobjectHandler3810 bool found(APFloat &Value, QualType SubobjType) {
3811 Result = APValue(Value);
3812 return true;
3813 }
3814 };
3815 } // end anonymous namespace
3816
3817 /// 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)3818 static bool extractSubobject(EvalInfo &Info, const Expr *E,
3819 const CompleteObject &Obj,
3820 const SubobjectDesignator &Sub, APValue &Result,
3821 AccessKinds AK = AK_Read) {
3822 assert(AK == AK_Read || AK == AK_ReadObjectRepresentation);
3823 ExtractSubobjectHandler Handler = {Info, E, Result, AK};
3824 return findSubobject(Info, E, Obj, Sub, Handler);
3825 }
3826
3827 namespace {
3828 struct ModifySubobjectHandler {
3829 EvalInfo &Info;
3830 APValue &NewVal;
3831 const Expr *E;
3832
3833 typedef bool result_type;
3834 static const AccessKinds AccessKind = AK_Assign;
3835
checkConst__anon6b379bbb0b11::ModifySubobjectHandler3836 bool checkConst(QualType QT) {
3837 // Assigning to a const object has undefined behavior.
3838 if (QT.isConstQualified()) {
3839 Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT;
3840 return false;
3841 }
3842 return true;
3843 }
3844
failed__anon6b379bbb0b11::ModifySubobjectHandler3845 bool failed() { return false; }
found__anon6b379bbb0b11::ModifySubobjectHandler3846 bool found(APValue &Subobj, QualType SubobjType) {
3847 if (!checkConst(SubobjType))
3848 return false;
3849 // We've been given ownership of NewVal, so just swap it in.
3850 Subobj.swap(NewVal);
3851 return true;
3852 }
found__anon6b379bbb0b11::ModifySubobjectHandler3853 bool found(APSInt &Value, QualType SubobjType) {
3854 if (!checkConst(SubobjType))
3855 return false;
3856 if (!NewVal.isInt()) {
3857 // Maybe trying to write a cast pointer value into a complex?
3858 Info.FFDiag(E);
3859 return false;
3860 }
3861 Value = NewVal.getInt();
3862 return true;
3863 }
found__anon6b379bbb0b11::ModifySubobjectHandler3864 bool found(APFloat &Value, QualType SubobjType) {
3865 if (!checkConst(SubobjType))
3866 return false;
3867 Value = NewVal.getFloat();
3868 return true;
3869 }
3870 };
3871 } // end anonymous namespace
3872
3873 const AccessKinds ModifySubobjectHandler::AccessKind;
3874
3875 /// 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)3876 static bool modifySubobject(EvalInfo &Info, const Expr *E,
3877 const CompleteObject &Obj,
3878 const SubobjectDesignator &Sub,
3879 APValue &NewVal) {
3880 ModifySubobjectHandler Handler = { Info, NewVal, E };
3881 return findSubobject(Info, E, Obj, Sub, Handler);
3882 }
3883
3884 /// Find the position where two subobject designators diverge, or equivalently
3885 /// the length of the common initial subsequence.
FindDesignatorMismatch(QualType ObjType,const SubobjectDesignator & A,const SubobjectDesignator & B,bool & WasArrayIndex)3886 static unsigned FindDesignatorMismatch(QualType ObjType,
3887 const SubobjectDesignator &A,
3888 const SubobjectDesignator &B,
3889 bool &WasArrayIndex) {
3890 unsigned I = 0, N = std::min(A.Entries.size(), B.Entries.size());
3891 for (/**/; I != N; ++I) {
3892 if (!ObjType.isNull() &&
3893 (ObjType->isArrayType() || ObjType->isAnyComplexType())) {
3894 // Next subobject is an array element.
3895 if (A.Entries[I].getAsArrayIndex() != B.Entries[I].getAsArrayIndex()) {
3896 WasArrayIndex = true;
3897 return I;
3898 }
3899 if (ObjType->isAnyComplexType())
3900 ObjType = ObjType->castAs<ComplexType>()->getElementType();
3901 else
3902 ObjType = ObjType->castAsArrayTypeUnsafe()->getElementType();
3903 } else {
3904 if (A.Entries[I].getAsBaseOrMember() !=
3905 B.Entries[I].getAsBaseOrMember()) {
3906 WasArrayIndex = false;
3907 return I;
3908 }
3909 if (const FieldDecl *FD = getAsField(A.Entries[I]))
3910 // Next subobject is a field.
3911 ObjType = FD->getType();
3912 else
3913 // Next subobject is a base class.
3914 ObjType = QualType();
3915 }
3916 }
3917 WasArrayIndex = false;
3918 return I;
3919 }
3920
3921 /// Determine whether the given subobject designators refer to elements of the
3922 /// same array object.
AreElementsOfSameArray(QualType ObjType,const SubobjectDesignator & A,const SubobjectDesignator & B)3923 static bool AreElementsOfSameArray(QualType ObjType,
3924 const SubobjectDesignator &A,
3925 const SubobjectDesignator &B) {
3926 if (A.Entries.size() != B.Entries.size())
3927 return false;
3928
3929 bool IsArray = A.MostDerivedIsArrayElement;
3930 if (IsArray && A.MostDerivedPathLength != A.Entries.size())
3931 // A is a subobject of the array element.
3932 return false;
3933
3934 // If A (and B) designates an array element, the last entry will be the array
3935 // index. That doesn't have to match. Otherwise, we're in the 'implicit array
3936 // of length 1' case, and the entire path must match.
3937 bool WasArrayIndex;
3938 unsigned CommonLength = FindDesignatorMismatch(ObjType, A, B, WasArrayIndex);
3939 return CommonLength >= A.Entries.size() - IsArray;
3940 }
3941
3942 /// Find the complete object to which an LValue refers.
findCompleteObject(EvalInfo & Info,const Expr * E,AccessKinds AK,const LValue & LVal,QualType LValType)3943 static CompleteObject findCompleteObject(EvalInfo &Info, const Expr *E,
3944 AccessKinds AK, const LValue &LVal,
3945 QualType LValType) {
3946 if (LVal.InvalidBase) {
3947 Info.FFDiag(E);
3948 return CompleteObject();
3949 }
3950
3951 if (!LVal.Base) {
3952 Info.FFDiag(E, diag::note_constexpr_access_null) << AK;
3953 return CompleteObject();
3954 }
3955
3956 CallStackFrame *Frame = nullptr;
3957 unsigned Depth = 0;
3958 if (LVal.getLValueCallIndex()) {
3959 std::tie(Frame, Depth) =
3960 Info.getCallFrameAndDepth(LVal.getLValueCallIndex());
3961 if (!Frame) {
3962 Info.FFDiag(E, diag::note_constexpr_lifetime_ended, 1)
3963 << AK << LVal.Base.is<const ValueDecl*>();
3964 NoteLValueLocation(Info, LVal.Base);
3965 return CompleteObject();
3966 }
3967 }
3968
3969 bool IsAccess = isAnyAccess(AK);
3970
3971 // C++11 DR1311: An lvalue-to-rvalue conversion on a volatile-qualified type
3972 // is not a constant expression (even if the object is non-volatile). We also
3973 // apply this rule to C++98, in order to conform to the expected 'volatile'
3974 // semantics.
3975 if (isFormalAccess(AK) && LValType.isVolatileQualified()) {
3976 if (Info.getLangOpts().CPlusPlus)
3977 Info.FFDiag(E, diag::note_constexpr_access_volatile_type)
3978 << AK << LValType;
3979 else
3980 Info.FFDiag(E);
3981 return CompleteObject();
3982 }
3983
3984 // Compute value storage location and type of base object.
3985 APValue *BaseVal = nullptr;
3986 QualType BaseType = getType(LVal.Base);
3987
3988 if (Info.getLangOpts().CPlusPlus14 && LVal.Base == Info.EvaluatingDecl &&
3989 lifetimeStartedInEvaluation(Info, LVal.Base)) {
3990 // This is the object whose initializer we're evaluating, so its lifetime
3991 // started in the current evaluation.
3992 BaseVal = Info.EvaluatingDeclValue;
3993 } else if (const ValueDecl *D = LVal.Base.dyn_cast<const ValueDecl *>()) {
3994 // Allow reading from a GUID declaration.
3995 if (auto *GD = dyn_cast<MSGuidDecl>(D)) {
3996 if (isModification(AK)) {
3997 // All the remaining cases do not permit modification of the object.
3998 Info.FFDiag(E, diag::note_constexpr_modify_global);
3999 return CompleteObject();
4000 }
4001 APValue &V = GD->getAsAPValue();
4002 if (V.isAbsent()) {
4003 Info.FFDiag(E, diag::note_constexpr_unsupported_layout)
4004 << GD->getType();
4005 return CompleteObject();
4006 }
4007 return CompleteObject(LVal.Base, &V, GD->getType());
4008 }
4009
4010 // Allow reading from template parameter objects.
4011 if (auto *TPO = dyn_cast<TemplateParamObjectDecl>(D)) {
4012 if (isModification(AK)) {
4013 Info.FFDiag(E, diag::note_constexpr_modify_global);
4014 return CompleteObject();
4015 }
4016 return CompleteObject(LVal.Base, const_cast<APValue *>(&TPO->getValue()),
4017 TPO->getType());
4018 }
4019
4020 // In C++98, const, non-volatile integers initialized with ICEs are ICEs.
4021 // In C++11, constexpr, non-volatile variables initialized with constant
4022 // expressions are constant expressions too. Inside constexpr functions,
4023 // parameters are constant expressions even if they're non-const.
4024 // In C++1y, objects local to a constant expression (those with a Frame) are
4025 // both readable and writable inside constant expressions.
4026 // In C, such things can also be folded, although they are not ICEs.
4027 const VarDecl *VD = dyn_cast<VarDecl>(D);
4028 if (VD) {
4029 if (const VarDecl *VDef = VD->getDefinition(Info.Ctx))
4030 VD = VDef;
4031 }
4032 if (!VD || VD->isInvalidDecl()) {
4033 Info.FFDiag(E);
4034 return CompleteObject();
4035 }
4036
4037 bool IsConstant = BaseType.isConstant(Info.Ctx);
4038
4039 // Unless we're looking at a local variable or argument in a constexpr call,
4040 // the variable we're reading must be const.
4041 if (!Frame) {
4042 if (IsAccess && isa<ParmVarDecl>(VD)) {
4043 // Access of a parameter that's not associated with a frame isn't going
4044 // to work out, but we can leave it to evaluateVarDeclInit to provide a
4045 // suitable diagnostic.
4046 } else if (Info.getLangOpts().CPlusPlus14 &&
4047 lifetimeStartedInEvaluation(Info, LVal.Base)) {
4048 // OK, we can read and modify an object if we're in the process of
4049 // evaluating its initializer, because its lifetime began in this
4050 // evaluation.
4051 } else if (isModification(AK)) {
4052 // All the remaining cases do not permit modification of the object.
4053 Info.FFDiag(E, diag::note_constexpr_modify_global);
4054 return CompleteObject();
4055 } else if (VD->isConstexpr()) {
4056 // OK, we can read this variable.
4057 } else if (BaseType->isIntegralOrEnumerationType()) {
4058 if (!IsConstant) {
4059 if (!IsAccess)
4060 return CompleteObject(LVal.getLValueBase(), nullptr, BaseType);
4061 if (Info.getLangOpts().CPlusPlus) {
4062 Info.FFDiag(E, diag::note_constexpr_ltor_non_const_int, 1) << VD;
4063 Info.Note(VD->getLocation(), diag::note_declared_at);
4064 } else {
4065 Info.FFDiag(E);
4066 }
4067 return CompleteObject();
4068 }
4069 } else if (!IsAccess) {
4070 return CompleteObject(LVal.getLValueBase(), nullptr, BaseType);
4071 } else if (IsConstant && Info.checkingPotentialConstantExpression() &&
4072 BaseType->isLiteralType(Info.Ctx) && !VD->hasDefinition()) {
4073 // This variable might end up being constexpr. Don't diagnose it yet.
4074 } else if (IsConstant) {
4075 // Keep evaluating to see what we can do. In particular, we support
4076 // folding of const floating-point types, in order to make static const
4077 // data members of such types (supported as an extension) more useful.
4078 if (Info.getLangOpts().CPlusPlus) {
4079 Info.CCEDiag(E, Info.getLangOpts().CPlusPlus11
4080 ? diag::note_constexpr_ltor_non_constexpr
4081 : diag::note_constexpr_ltor_non_integral, 1)
4082 << VD << BaseType;
4083 Info.Note(VD->getLocation(), diag::note_declared_at);
4084 } else {
4085 Info.CCEDiag(E);
4086 }
4087 } else {
4088 // Never allow reading a non-const value.
4089 if (Info.getLangOpts().CPlusPlus) {
4090 Info.FFDiag(E, Info.getLangOpts().CPlusPlus11
4091 ? diag::note_constexpr_ltor_non_constexpr
4092 : diag::note_constexpr_ltor_non_integral, 1)
4093 << VD << BaseType;
4094 Info.Note(VD->getLocation(), diag::note_declared_at);
4095 } else {
4096 Info.FFDiag(E);
4097 }
4098 return CompleteObject();
4099 }
4100 }
4101
4102 if (!evaluateVarDeclInit(Info, E, VD, Frame, LVal.getLValueVersion(), BaseVal))
4103 return CompleteObject();
4104 } else if (DynamicAllocLValue DA = LVal.Base.dyn_cast<DynamicAllocLValue>()) {
4105 Optional<DynAlloc*> Alloc = Info.lookupDynamicAlloc(DA);
4106 if (!Alloc) {
4107 Info.FFDiag(E, diag::note_constexpr_access_deleted_object) << AK;
4108 return CompleteObject();
4109 }
4110 return CompleteObject(LVal.Base, &(*Alloc)->Value,
4111 LVal.Base.getDynamicAllocType());
4112 } else {
4113 const Expr *Base = LVal.Base.dyn_cast<const Expr*>();
4114
4115 if (!Frame) {
4116 if (const MaterializeTemporaryExpr *MTE =
4117 dyn_cast_or_null<MaterializeTemporaryExpr>(Base)) {
4118 assert(MTE->getStorageDuration() == SD_Static &&
4119 "should have a frame for a non-global materialized temporary");
4120
4121 // C++20 [expr.const]p4: [DR2126]
4122 // An object or reference is usable in constant expressions if it is
4123 // - a temporary object of non-volatile const-qualified literal type
4124 // whose lifetime is extended to that of a variable that is usable
4125 // in constant expressions
4126 //
4127 // C++20 [expr.const]p5:
4128 // an lvalue-to-rvalue conversion [is not allowed unless it applies to]
4129 // - a non-volatile glvalue that refers to an object that is usable
4130 // in constant expressions, or
4131 // - a non-volatile glvalue of literal type that refers to a
4132 // non-volatile object whose lifetime began within the evaluation
4133 // of E;
4134 //
4135 // C++11 misses the 'began within the evaluation of e' check and
4136 // instead allows all temporaries, including things like:
4137 // int &&r = 1;
4138 // int x = ++r;
4139 // constexpr int k = r;
4140 // Therefore we use the C++14-onwards rules in C++11 too.
4141 //
4142 // Note that temporaries whose lifetimes began while evaluating a
4143 // variable's constructor are not usable while evaluating the
4144 // corresponding destructor, not even if they're of const-qualified
4145 // types.
4146 if (!MTE->isUsableInConstantExpressions(Info.Ctx) &&
4147 !lifetimeStartedInEvaluation(Info, LVal.Base)) {
4148 if (!IsAccess)
4149 return CompleteObject(LVal.getLValueBase(), nullptr, BaseType);
4150 Info.FFDiag(E, diag::note_constexpr_access_static_temporary, 1) << AK;
4151 Info.Note(MTE->getExprLoc(), diag::note_constexpr_temporary_here);
4152 return CompleteObject();
4153 }
4154
4155 BaseVal = MTE->getOrCreateValue(false);
4156 assert(BaseVal && "got reference to unevaluated temporary");
4157 } else {
4158 if (!IsAccess)
4159 return CompleteObject(LVal.getLValueBase(), nullptr, BaseType);
4160 APValue Val;
4161 LVal.moveInto(Val);
4162 Info.FFDiag(E, diag::note_constexpr_access_unreadable_object)
4163 << AK
4164 << Val.getAsString(Info.Ctx,
4165 Info.Ctx.getLValueReferenceType(LValType));
4166 NoteLValueLocation(Info, LVal.Base);
4167 return CompleteObject();
4168 }
4169 } else {
4170 BaseVal = Frame->getTemporary(Base, LVal.Base.getVersion());
4171 assert(BaseVal && "missing value for temporary");
4172 }
4173 }
4174
4175 // In C++14, we can't safely access any mutable state when we might be
4176 // evaluating after an unmodeled side effect. Parameters are modeled as state
4177 // in the caller, but aren't visible once the call returns, so they can be
4178 // modified in a speculatively-evaluated call.
4179 //
4180 // FIXME: Not all local state is mutable. Allow local constant subobjects
4181 // to be read here (but take care with 'mutable' fields).
4182 unsigned VisibleDepth = Depth;
4183 if (llvm::isa_and_nonnull<ParmVarDecl>(
4184 LVal.Base.dyn_cast<const ValueDecl *>()))
4185 ++VisibleDepth;
4186 if ((Frame && Info.getLangOpts().CPlusPlus14 &&
4187 Info.EvalStatus.HasSideEffects) ||
4188 (isModification(AK) && VisibleDepth < Info.SpeculativeEvaluationDepth))
4189 return CompleteObject();
4190
4191 return CompleteObject(LVal.getLValueBase(), BaseVal, BaseType);
4192 }
4193
4194 /// Perform an lvalue-to-rvalue conversion on the given glvalue. This
4195 /// can also be used for 'lvalue-to-lvalue' conversions for looking up the
4196 /// glvalue referred to by an entity of reference type.
4197 ///
4198 /// \param Info - Information about the ongoing evaluation.
4199 /// \param Conv - The expression for which we are performing the conversion.
4200 /// Used for diagnostics.
4201 /// \param Type - The type of the glvalue (before stripping cv-qualifiers in the
4202 /// case of a non-class type).
4203 /// \param LVal - The glvalue on which we are attempting to perform this action.
4204 /// \param RVal - The produced value will be placed here.
4205 /// \param WantObjectRepresentation - If true, we're looking for the object
4206 /// representation rather than the value, and in particular,
4207 /// there is no requirement that the result be fully initialized.
4208 static bool
handleLValueToRValueConversion(EvalInfo & Info,const Expr * Conv,QualType Type,const LValue & LVal,APValue & RVal,bool WantObjectRepresentation=false)4209 handleLValueToRValueConversion(EvalInfo &Info, const Expr *Conv, QualType Type,
4210 const LValue &LVal, APValue &RVal,
4211 bool WantObjectRepresentation = false) {
4212 if (LVal.Designator.Invalid)
4213 return false;
4214
4215 // Check for special cases where there is no existing APValue to look at.
4216 const Expr *Base = LVal.Base.dyn_cast<const Expr*>();
4217
4218 AccessKinds AK =
4219 WantObjectRepresentation ? AK_ReadObjectRepresentation : AK_Read;
4220
4221 if (Base && !LVal.getLValueCallIndex() && !Type.isVolatileQualified()) {
4222 if (const CompoundLiteralExpr *CLE = dyn_cast<CompoundLiteralExpr>(Base)) {
4223 // In C99, a CompoundLiteralExpr is an lvalue, and we defer evaluating the
4224 // initializer until now for such expressions. Such an expression can't be
4225 // an ICE in C, so this only matters for fold.
4226 if (Type.isVolatileQualified()) {
4227 Info.FFDiag(Conv);
4228 return false;
4229 }
4230 APValue Lit;
4231 if (!Evaluate(Lit, Info, CLE->getInitializer()))
4232 return false;
4233 CompleteObject LitObj(LVal.Base, &Lit, Base->getType());
4234 return extractSubobject(Info, Conv, LitObj, LVal.Designator, RVal, AK);
4235 } else if (isa<StringLiteral>(Base) || isa<PredefinedExpr>(Base)) {
4236 // Special-case character extraction so we don't have to construct an
4237 // APValue for the whole string.
4238 assert(LVal.Designator.Entries.size() <= 1 &&
4239 "Can only read characters from string literals");
4240 if (LVal.Designator.Entries.empty()) {
4241 // Fail for now for LValue to RValue conversion of an array.
4242 // (This shouldn't show up in C/C++, but it could be triggered by a
4243 // weird EvaluateAsRValue call from a tool.)
4244 Info.FFDiag(Conv);
4245 return false;
4246 }
4247 if (LVal.Designator.isOnePastTheEnd()) {
4248 if (Info.getLangOpts().CPlusPlus11)
4249 Info.FFDiag(Conv, diag::note_constexpr_access_past_end) << AK;
4250 else
4251 Info.FFDiag(Conv);
4252 return false;
4253 }
4254 uint64_t CharIndex = LVal.Designator.Entries[0].getAsArrayIndex();
4255 RVal = APValue(extractStringLiteralCharacter(Info, Base, CharIndex));
4256 return true;
4257 }
4258 }
4259
4260 CompleteObject Obj = findCompleteObject(Info, Conv, AK, LVal, Type);
4261 return Obj && extractSubobject(Info, Conv, Obj, LVal.Designator, RVal, AK);
4262 }
4263
4264 /// Perform an assignment of Val to LVal. Takes ownership of Val.
handleAssignment(EvalInfo & Info,const Expr * E,const LValue & LVal,QualType LValType,APValue & Val)4265 static bool handleAssignment(EvalInfo &Info, const Expr *E, const LValue &LVal,
4266 QualType LValType, APValue &Val) {
4267 if (LVal.Designator.Invalid)
4268 return false;
4269
4270 if (!Info.getLangOpts().CPlusPlus14) {
4271 Info.FFDiag(E);
4272 return false;
4273 }
4274
4275 CompleteObject Obj = findCompleteObject(Info, E, AK_Assign, LVal, LValType);
4276 return Obj && modifySubobject(Info, E, Obj, LVal.Designator, Val);
4277 }
4278
4279 namespace {
4280 struct CompoundAssignSubobjectHandler {
4281 EvalInfo &Info;
4282 const CompoundAssignOperator *E;
4283 QualType PromotedLHSType;
4284 BinaryOperatorKind Opcode;
4285 const APValue &RHS;
4286
4287 static const AccessKinds AccessKind = AK_Assign;
4288
4289 typedef bool result_type;
4290
checkConst__anon6b379bbb0c11::CompoundAssignSubobjectHandler4291 bool checkConst(QualType QT) {
4292 // Assigning to a const object has undefined behavior.
4293 if (QT.isConstQualified()) {
4294 Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT;
4295 return false;
4296 }
4297 return true;
4298 }
4299
failed__anon6b379bbb0c11::CompoundAssignSubobjectHandler4300 bool failed() { return false; }
found__anon6b379bbb0c11::CompoundAssignSubobjectHandler4301 bool found(APValue &Subobj, QualType SubobjType) {
4302 switch (Subobj.getKind()) {
4303 case APValue::Int:
4304 return found(Subobj.getInt(), SubobjType);
4305 case APValue::Float:
4306 return found(Subobj.getFloat(), SubobjType);
4307 case APValue::ComplexInt:
4308 case APValue::ComplexFloat:
4309 // FIXME: Implement complex compound assignment.
4310 Info.FFDiag(E);
4311 return false;
4312 case APValue::LValue:
4313 return foundPointer(Subobj, SubobjType);
4314 case APValue::Vector:
4315 return foundVector(Subobj, SubobjType);
4316 default:
4317 // FIXME: can this happen?
4318 Info.FFDiag(E);
4319 return false;
4320 }
4321 }
4322
foundVector__anon6b379bbb0c11::CompoundAssignSubobjectHandler4323 bool foundVector(APValue &Value, QualType SubobjType) {
4324 if (!checkConst(SubobjType))
4325 return false;
4326
4327 if (!SubobjType->isVectorType()) {
4328 Info.FFDiag(E);
4329 return false;
4330 }
4331 return handleVectorVectorBinOp(Info, E, Opcode, Value, RHS);
4332 }
4333
found__anon6b379bbb0c11::CompoundAssignSubobjectHandler4334 bool found(APSInt &Value, QualType SubobjType) {
4335 if (!checkConst(SubobjType))
4336 return false;
4337
4338 if (!SubobjType->isIntegerType()) {
4339 // We don't support compound assignment on integer-cast-to-pointer
4340 // values.
4341 Info.FFDiag(E);
4342 return false;
4343 }
4344
4345 if (RHS.isInt()) {
4346 APSInt LHS =
4347 HandleIntToIntCast(Info, E, PromotedLHSType, SubobjType, Value);
4348 if (!handleIntIntBinOp(Info, E, LHS, Opcode, RHS.getInt(), LHS))
4349 return false;
4350 Value = HandleIntToIntCast(Info, E, SubobjType, PromotedLHSType, LHS);
4351 return true;
4352 } else if (RHS.isFloat()) {
4353 const FPOptions FPO = E->getFPFeaturesInEffect(
4354 Info.Ctx.getLangOpts());
4355 APFloat FValue(0.0);
4356 return HandleIntToFloatCast(Info, E, FPO, SubobjType, Value,
4357 PromotedLHSType, FValue) &&
4358 handleFloatFloatBinOp(Info, E, FValue, Opcode, RHS.getFloat()) &&
4359 HandleFloatToIntCast(Info, E, PromotedLHSType, FValue, SubobjType,
4360 Value);
4361 }
4362
4363 Info.FFDiag(E);
4364 return false;
4365 }
found__anon6b379bbb0c11::CompoundAssignSubobjectHandler4366 bool found(APFloat &Value, QualType SubobjType) {
4367 return checkConst(SubobjType) &&
4368 HandleFloatToFloatCast(Info, E, SubobjType, PromotedLHSType,
4369 Value) &&
4370 handleFloatFloatBinOp(Info, E, Value, Opcode, RHS.getFloat()) &&
4371 HandleFloatToFloatCast(Info, E, PromotedLHSType, SubobjType, Value);
4372 }
foundPointer__anon6b379bbb0c11::CompoundAssignSubobjectHandler4373 bool foundPointer(APValue &Subobj, QualType SubobjType) {
4374 if (!checkConst(SubobjType))
4375 return false;
4376
4377 QualType PointeeType;
4378 if (const PointerType *PT = SubobjType->getAs<PointerType>())
4379 PointeeType = PT->getPointeeType();
4380
4381 if (PointeeType.isNull() || !RHS.isInt() ||
4382 (Opcode != BO_Add && Opcode != BO_Sub)) {
4383 Info.FFDiag(E);
4384 return false;
4385 }
4386
4387 APSInt Offset = RHS.getInt();
4388 if (Opcode == BO_Sub)
4389 negateAsSigned(Offset);
4390
4391 LValue LVal;
4392 LVal.setFrom(Info.Ctx, Subobj);
4393 if (!HandleLValueArrayAdjustment(Info, E, LVal, PointeeType, Offset))
4394 return false;
4395 LVal.moveInto(Subobj);
4396 return true;
4397 }
4398 };
4399 } // end anonymous namespace
4400
4401 const AccessKinds CompoundAssignSubobjectHandler::AccessKind;
4402
4403 /// 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)4404 static bool handleCompoundAssignment(EvalInfo &Info,
4405 const CompoundAssignOperator *E,
4406 const LValue &LVal, QualType LValType,
4407 QualType PromotedLValType,
4408 BinaryOperatorKind Opcode,
4409 const APValue &RVal) {
4410 if (LVal.Designator.Invalid)
4411 return false;
4412
4413 if (!Info.getLangOpts().CPlusPlus14) {
4414 Info.FFDiag(E);
4415 return false;
4416 }
4417
4418 CompleteObject Obj = findCompleteObject(Info, E, AK_Assign, LVal, LValType);
4419 CompoundAssignSubobjectHandler Handler = { Info, E, PromotedLValType, Opcode,
4420 RVal };
4421 return Obj && findSubobject(Info, E, Obj, LVal.Designator, Handler);
4422 }
4423
4424 namespace {
4425 struct IncDecSubobjectHandler {
4426 EvalInfo &Info;
4427 const UnaryOperator *E;
4428 AccessKinds AccessKind;
4429 APValue *Old;
4430
4431 typedef bool result_type;
4432
checkConst__anon6b379bbb0d11::IncDecSubobjectHandler4433 bool checkConst(QualType QT) {
4434 // Assigning to a const object has undefined behavior.
4435 if (QT.isConstQualified()) {
4436 Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT;
4437 return false;
4438 }
4439 return true;
4440 }
4441
failed__anon6b379bbb0d11::IncDecSubobjectHandler4442 bool failed() { return false; }
found__anon6b379bbb0d11::IncDecSubobjectHandler4443 bool found(APValue &Subobj, QualType SubobjType) {
4444 // Stash the old value. Also clear Old, so we don't clobber it later
4445 // if we're post-incrementing a complex.
4446 if (Old) {
4447 *Old = Subobj;
4448 Old = nullptr;
4449 }
4450
4451 switch (Subobj.getKind()) {
4452 case APValue::Int:
4453 return found(Subobj.getInt(), SubobjType);
4454 case APValue::Float:
4455 return found(Subobj.getFloat(), SubobjType);
4456 case APValue::ComplexInt:
4457 return found(Subobj.getComplexIntReal(),
4458 SubobjType->castAs<ComplexType>()->getElementType()
4459 .withCVRQualifiers(SubobjType.getCVRQualifiers()));
4460 case APValue::ComplexFloat:
4461 return found(Subobj.getComplexFloatReal(),
4462 SubobjType->castAs<ComplexType>()->getElementType()
4463 .withCVRQualifiers(SubobjType.getCVRQualifiers()));
4464 case APValue::LValue:
4465 return foundPointer(Subobj, SubobjType);
4466 default:
4467 // FIXME: can this happen?
4468 Info.FFDiag(E);
4469 return false;
4470 }
4471 }
found__anon6b379bbb0d11::IncDecSubobjectHandler4472 bool found(APSInt &Value, QualType SubobjType) {
4473 if (!checkConst(SubobjType))
4474 return false;
4475
4476 if (!SubobjType->isIntegerType()) {
4477 // We don't support increment / decrement on integer-cast-to-pointer
4478 // values.
4479 Info.FFDiag(E);
4480 return false;
4481 }
4482
4483 if (Old) *Old = APValue(Value);
4484
4485 // bool arithmetic promotes to int, and the conversion back to bool
4486 // doesn't reduce mod 2^n, so special-case it.
4487 if (SubobjType->isBooleanType()) {
4488 if (AccessKind == AK_Increment)
4489 Value = 1;
4490 else
4491 Value = !Value;
4492 return true;
4493 }
4494
4495 bool WasNegative = Value.isNegative();
4496 if (AccessKind == AK_Increment) {
4497 ++Value;
4498
4499 if (!WasNegative && Value.isNegative() && E->canOverflow()) {
4500 APSInt ActualValue(Value, /*IsUnsigned*/true);
4501 return HandleOverflow(Info, E, ActualValue, SubobjType);
4502 }
4503 } else {
4504 --Value;
4505
4506 if (WasNegative && !Value.isNegative() && E->canOverflow()) {
4507 unsigned BitWidth = Value.getBitWidth();
4508 APSInt ActualValue(Value.sext(BitWidth + 1), /*IsUnsigned*/false);
4509 ActualValue.setBit(BitWidth);
4510 return HandleOverflow(Info, E, ActualValue, SubobjType);
4511 }
4512 }
4513 return true;
4514 }
found__anon6b379bbb0d11::IncDecSubobjectHandler4515 bool found(APFloat &Value, QualType SubobjType) {
4516 if (!checkConst(SubobjType))
4517 return false;
4518
4519 if (Old) *Old = APValue(Value);
4520
4521 APFloat One(Value.getSemantics(), 1);
4522 if (AccessKind == AK_Increment)
4523 Value.add(One, APFloat::rmNearestTiesToEven);
4524 else
4525 Value.subtract(One, APFloat::rmNearestTiesToEven);
4526 return true;
4527 }
foundPointer__anon6b379bbb0d11::IncDecSubobjectHandler4528 bool foundPointer(APValue &Subobj, QualType SubobjType) {
4529 if (!checkConst(SubobjType))
4530 return false;
4531
4532 QualType PointeeType;
4533 if (const PointerType *PT = SubobjType->getAs<PointerType>())
4534 PointeeType = PT->getPointeeType();
4535 else {
4536 Info.FFDiag(E);
4537 return false;
4538 }
4539
4540 LValue LVal;
4541 LVal.setFrom(Info.Ctx, Subobj);
4542 if (!HandleLValueArrayAdjustment(Info, E, LVal, PointeeType,
4543 AccessKind == AK_Increment ? 1 : -1))
4544 return false;
4545 LVal.moveInto(Subobj);
4546 return true;
4547 }
4548 };
4549 } // end anonymous namespace
4550
4551 /// Perform an increment or decrement on LVal.
handleIncDec(EvalInfo & Info,const Expr * E,const LValue & LVal,QualType LValType,bool IsIncrement,APValue * Old)4552 static bool handleIncDec(EvalInfo &Info, const Expr *E, const LValue &LVal,
4553 QualType LValType, bool IsIncrement, APValue *Old) {
4554 if (LVal.Designator.Invalid)
4555 return false;
4556
4557 if (!Info.getLangOpts().CPlusPlus14) {
4558 Info.FFDiag(E);
4559 return false;
4560 }
4561
4562 AccessKinds AK = IsIncrement ? AK_Increment : AK_Decrement;
4563 CompleteObject Obj = findCompleteObject(Info, E, AK, LVal, LValType);
4564 IncDecSubobjectHandler Handler = {Info, cast<UnaryOperator>(E), AK, Old};
4565 return Obj && findSubobject(Info, E, Obj, LVal.Designator, Handler);
4566 }
4567
4568 /// Build an lvalue for the object argument of a member function call.
EvaluateObjectArgument(EvalInfo & Info,const Expr * Object,LValue & This)4569 static bool EvaluateObjectArgument(EvalInfo &Info, const Expr *Object,
4570 LValue &This) {
4571 if (Object->getType()->isPointerType() && Object->isRValue())
4572 return EvaluatePointer(Object, This, Info);
4573
4574 if (Object->isGLValue())
4575 return EvaluateLValue(Object, This, Info);
4576
4577 if (Object->getType()->isLiteralType(Info.Ctx))
4578 return EvaluateTemporary(Object, This, Info);
4579
4580 Info.FFDiag(Object, diag::note_constexpr_nonliteral) << Object->getType();
4581 return false;
4582 }
4583
4584 /// HandleMemberPointerAccess - Evaluate a member access operation and build an
4585 /// lvalue referring to the result.
4586 ///
4587 /// \param Info - Information about the ongoing evaluation.
4588 /// \param LV - An lvalue referring to the base of the member pointer.
4589 /// \param RHS - The member pointer expression.
4590 /// \param IncludeMember - Specifies whether the member itself is included in
4591 /// the resulting LValue subobject designator. This is not possible when
4592 /// creating a bound member function.
4593 /// \return The field or method declaration to which the member pointer refers,
4594 /// or 0 if evaluation fails.
HandleMemberPointerAccess(EvalInfo & Info,QualType LVType,LValue & LV,const Expr * RHS,bool IncludeMember=true)4595 static const ValueDecl *HandleMemberPointerAccess(EvalInfo &Info,
4596 QualType LVType,
4597 LValue &LV,
4598 const Expr *RHS,
4599 bool IncludeMember = true) {
4600 MemberPtr MemPtr;
4601 if (!EvaluateMemberPointer(RHS, MemPtr, Info))
4602 return nullptr;
4603
4604 // C++11 [expr.mptr.oper]p6: If the second operand is the null pointer to
4605 // member value, the behavior is undefined.
4606 if (!MemPtr.getDecl()) {
4607 // FIXME: Specific diagnostic.
4608 Info.FFDiag(RHS);
4609 return nullptr;
4610 }
4611
4612 if (MemPtr.isDerivedMember()) {
4613 // This is a member of some derived class. Truncate LV appropriately.
4614 // The end of the derived-to-base path for the base object must match the
4615 // derived-to-base path for the member pointer.
4616 if (LV.Designator.MostDerivedPathLength + MemPtr.Path.size() >
4617 LV.Designator.Entries.size()) {
4618 Info.FFDiag(RHS);
4619 return nullptr;
4620 }
4621 unsigned PathLengthToMember =
4622 LV.Designator.Entries.size() - MemPtr.Path.size();
4623 for (unsigned I = 0, N = MemPtr.Path.size(); I != N; ++I) {
4624 const CXXRecordDecl *LVDecl = getAsBaseClass(
4625 LV.Designator.Entries[PathLengthToMember + I]);
4626 const CXXRecordDecl *MPDecl = MemPtr.Path[I];
4627 if (LVDecl->getCanonicalDecl() != MPDecl->getCanonicalDecl()) {
4628 Info.FFDiag(RHS);
4629 return nullptr;
4630 }
4631 }
4632
4633 // Truncate the lvalue to the appropriate derived class.
4634 if (!CastToDerivedClass(Info, RHS, LV, MemPtr.getContainingRecord(),
4635 PathLengthToMember))
4636 return nullptr;
4637 } else if (!MemPtr.Path.empty()) {
4638 // Extend the LValue path with the member pointer's path.
4639 LV.Designator.Entries.reserve(LV.Designator.Entries.size() +
4640 MemPtr.Path.size() + IncludeMember);
4641
4642 // Walk down to the appropriate base class.
4643 if (const PointerType *PT = LVType->getAs<PointerType>())
4644 LVType = PT->getPointeeType();
4645 const CXXRecordDecl *RD = LVType->getAsCXXRecordDecl();
4646 assert(RD && "member pointer access on non-class-type expression");
4647 // The first class in the path is that of the lvalue.
4648 for (unsigned I = 1, N = MemPtr.Path.size(); I != N; ++I) {
4649 const CXXRecordDecl *Base = MemPtr.Path[N - I - 1];
4650 if (!HandleLValueDirectBase(Info, RHS, LV, RD, Base))
4651 return nullptr;
4652 RD = Base;
4653 }
4654 // Finally cast to the class containing the member.
4655 if (!HandleLValueDirectBase(Info, RHS, LV, RD,
4656 MemPtr.getContainingRecord()))
4657 return nullptr;
4658 }
4659
4660 // Add the member. Note that we cannot build bound member functions here.
4661 if (IncludeMember) {
4662 if (const FieldDecl *FD = dyn_cast<FieldDecl>(MemPtr.getDecl())) {
4663 if (!HandleLValueMember(Info, RHS, LV, FD))
4664 return nullptr;
4665 } else if (const IndirectFieldDecl *IFD =
4666 dyn_cast<IndirectFieldDecl>(MemPtr.getDecl())) {
4667 if (!HandleLValueIndirectMember(Info, RHS, LV, IFD))
4668 return nullptr;
4669 } else {
4670 llvm_unreachable("can't construct reference to bound member function");
4671 }
4672 }
4673
4674 return MemPtr.getDecl();
4675 }
4676
HandleMemberPointerAccess(EvalInfo & Info,const BinaryOperator * BO,LValue & LV,bool IncludeMember=true)4677 static const ValueDecl *HandleMemberPointerAccess(EvalInfo &Info,
4678 const BinaryOperator *BO,
4679 LValue &LV,
4680 bool IncludeMember = true) {
4681 assert(BO->getOpcode() == BO_PtrMemD || BO->getOpcode() == BO_PtrMemI);
4682
4683 if (!EvaluateObjectArgument(Info, BO->getLHS(), LV)) {
4684 if (Info.noteFailure()) {
4685 MemberPtr MemPtr;
4686 EvaluateMemberPointer(BO->getRHS(), MemPtr, Info);
4687 }
4688 return nullptr;
4689 }
4690
4691 return HandleMemberPointerAccess(Info, BO->getLHS()->getType(), LV,
4692 BO->getRHS(), IncludeMember);
4693 }
4694
4695 /// HandleBaseToDerivedCast - Apply the given base-to-derived cast operation on
4696 /// the provided lvalue, which currently refers to the base object.
HandleBaseToDerivedCast(EvalInfo & Info,const CastExpr * E,LValue & Result)4697 static bool HandleBaseToDerivedCast(EvalInfo &Info, const CastExpr *E,
4698 LValue &Result) {
4699 SubobjectDesignator &D = Result.Designator;
4700 if (D.Invalid || !Result.checkNullPointer(Info, E, CSK_Derived))
4701 return false;
4702
4703 QualType TargetQT = E->getType();
4704 if (const PointerType *PT = TargetQT->getAs<PointerType>())
4705 TargetQT = PT->getPointeeType();
4706
4707 // Check this cast lands within the final derived-to-base subobject path.
4708 if (D.MostDerivedPathLength + E->path_size() > D.Entries.size()) {
4709 Info.CCEDiag(E, diag::note_constexpr_invalid_downcast)
4710 << D.MostDerivedType << TargetQT;
4711 return false;
4712 }
4713
4714 // Check the type of the final cast. We don't need to check the path,
4715 // since a cast can only be formed if the path is unique.
4716 unsigned NewEntriesSize = D.Entries.size() - E->path_size();
4717 const CXXRecordDecl *TargetType = TargetQT->getAsCXXRecordDecl();
4718 const CXXRecordDecl *FinalType;
4719 if (NewEntriesSize == D.MostDerivedPathLength)
4720 FinalType = D.MostDerivedType->getAsCXXRecordDecl();
4721 else
4722 FinalType = getAsBaseClass(D.Entries[NewEntriesSize - 1]);
4723 if (FinalType->getCanonicalDecl() != TargetType->getCanonicalDecl()) {
4724 Info.CCEDiag(E, diag::note_constexpr_invalid_downcast)
4725 << D.MostDerivedType << TargetQT;
4726 return false;
4727 }
4728
4729 // Truncate the lvalue to the appropriate derived class.
4730 return CastToDerivedClass(Info, E, Result, TargetType, NewEntriesSize);
4731 }
4732
4733 /// Get the value to use for a default-initialized object of type T.
4734 /// Return false if it encounters something invalid.
getDefaultInitValue(QualType T,APValue & Result)4735 static bool getDefaultInitValue(QualType T, APValue &Result) {
4736 bool Success = true;
4737 if (auto *RD = T->getAsCXXRecordDecl()) {
4738 if (RD->isInvalidDecl()) {
4739 Result = APValue();
4740 return false;
4741 }
4742 if (RD->isUnion()) {
4743 Result = APValue((const FieldDecl *)nullptr);
4744 return true;
4745 }
4746 Result = APValue(APValue::UninitStruct(), RD->getNumBases(),
4747 std::distance(RD->field_begin(), RD->field_end()));
4748
4749 unsigned Index = 0;
4750 for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
4751 End = RD->bases_end();
4752 I != End; ++I, ++Index)
4753 Success &= getDefaultInitValue(I->getType(), Result.getStructBase(Index));
4754
4755 for (const auto *I : RD->fields()) {
4756 if (I->isUnnamedBitfield())
4757 continue;
4758 Success &= getDefaultInitValue(I->getType(),
4759 Result.getStructField(I->getFieldIndex()));
4760 }
4761 return Success;
4762 }
4763
4764 if (auto *AT =
4765 dyn_cast_or_null<ConstantArrayType>(T->getAsArrayTypeUnsafe())) {
4766 Result = APValue(APValue::UninitArray(), 0, AT->getSize().getZExtValue());
4767 if (Result.hasArrayFiller())
4768 Success &=
4769 getDefaultInitValue(AT->getElementType(), Result.getArrayFiller());
4770
4771 return Success;
4772 }
4773
4774 Result = APValue::IndeterminateValue();
4775 return true;
4776 }
4777
4778 namespace {
4779 enum EvalStmtResult {
4780 /// Evaluation failed.
4781 ESR_Failed,
4782 /// Hit a 'return' statement.
4783 ESR_Returned,
4784 /// Evaluation succeeded.
4785 ESR_Succeeded,
4786 /// Hit a 'continue' statement.
4787 ESR_Continue,
4788 /// Hit a 'break' statement.
4789 ESR_Break,
4790 /// Still scanning for 'case' or 'default' statement.
4791 ESR_CaseNotFound
4792 };
4793 }
4794
EvaluateVarDecl(EvalInfo & Info,const VarDecl * VD)4795 static bool EvaluateVarDecl(EvalInfo &Info, const VarDecl *VD) {
4796 // We don't need to evaluate the initializer for a static local.
4797 if (!VD->hasLocalStorage())
4798 return true;
4799
4800 LValue Result;
4801 APValue &Val = Info.CurrentCall->createTemporary(VD, VD->getType(),
4802 ScopeKind::Block, Result);
4803
4804 const Expr *InitE = VD->getInit();
4805 if (!InitE) {
4806 if (VD->getType()->isDependentType())
4807 return Info.noteSideEffect();
4808 return getDefaultInitValue(VD->getType(), Val);
4809 }
4810 if (InitE->isValueDependent())
4811 return false;
4812
4813 if (!EvaluateInPlace(Val, Info, Result, InitE)) {
4814 // Wipe out any partially-computed value, to allow tracking that this
4815 // evaluation failed.
4816 Val = APValue();
4817 return false;
4818 }
4819
4820 return true;
4821 }
4822
EvaluateDecl(EvalInfo & Info,const Decl * D)4823 static bool EvaluateDecl(EvalInfo &Info, const Decl *D) {
4824 bool OK = true;
4825
4826 if (const VarDecl *VD = dyn_cast<VarDecl>(D))
4827 OK &= EvaluateVarDecl(Info, VD);
4828
4829 if (const DecompositionDecl *DD = dyn_cast<DecompositionDecl>(D))
4830 for (auto *BD : DD->bindings())
4831 if (auto *VD = BD->getHoldingVar())
4832 OK &= EvaluateDecl(Info, VD);
4833
4834 return OK;
4835 }
4836
EvaluateDependentExpr(const Expr * E,EvalInfo & Info)4837 static bool EvaluateDependentExpr(const Expr *E, EvalInfo &Info) {
4838 assert(E->isValueDependent());
4839 if (Info.noteSideEffect())
4840 return true;
4841 assert(E->containsErrors() && "valid value-dependent expression should never "
4842 "reach invalid code path.");
4843 return false;
4844 }
4845
4846 /// Evaluate a condition (either a variable declaration or an expression).
EvaluateCond(EvalInfo & Info,const VarDecl * CondDecl,const Expr * Cond,bool & Result)4847 static bool EvaluateCond(EvalInfo &Info, const VarDecl *CondDecl,
4848 const Expr *Cond, bool &Result) {
4849 if (Cond->isValueDependent())
4850 return false;
4851 FullExpressionRAII Scope(Info);
4852 if (CondDecl && !EvaluateDecl(Info, CondDecl))
4853 return false;
4854 if (!EvaluateAsBooleanCondition(Cond, Result, Info))
4855 return false;
4856 return Scope.destroy();
4857 }
4858
4859 namespace {
4860 /// A location where the result (returned value) of evaluating a
4861 /// statement should be stored.
4862 struct StmtResult {
4863 /// The APValue that should be filled in with the returned value.
4864 APValue &Value;
4865 /// The location containing the result, if any (used to support RVO).
4866 const LValue *Slot;
4867 };
4868
4869 struct TempVersionRAII {
4870 CallStackFrame &Frame;
4871
TempVersionRAII__anon6b379bbb0f11::TempVersionRAII4872 TempVersionRAII(CallStackFrame &Frame) : Frame(Frame) {
4873 Frame.pushTempVersion();
4874 }
4875
~TempVersionRAII__anon6b379bbb0f11::TempVersionRAII4876 ~TempVersionRAII() {
4877 Frame.popTempVersion();
4878 }
4879 };
4880
4881 }
4882
4883 static EvalStmtResult EvaluateStmt(StmtResult &Result, EvalInfo &Info,
4884 const Stmt *S,
4885 const SwitchCase *SC = nullptr);
4886
4887 /// Evaluate the body of a loop, and translate the result as appropriate.
EvaluateLoopBody(StmtResult & Result,EvalInfo & Info,const Stmt * Body,const SwitchCase * Case=nullptr)4888 static EvalStmtResult EvaluateLoopBody(StmtResult &Result, EvalInfo &Info,
4889 const Stmt *Body,
4890 const SwitchCase *Case = nullptr) {
4891 BlockScopeRAII Scope(Info);
4892
4893 EvalStmtResult ESR = EvaluateStmt(Result, Info, Body, Case);
4894 if (ESR != ESR_Failed && ESR != ESR_CaseNotFound && !Scope.destroy())
4895 ESR = ESR_Failed;
4896
4897 switch (ESR) {
4898 case ESR_Break:
4899 return ESR_Succeeded;
4900 case ESR_Succeeded:
4901 case ESR_Continue:
4902 return ESR_Continue;
4903 case ESR_Failed:
4904 case ESR_Returned:
4905 case ESR_CaseNotFound:
4906 return ESR;
4907 }
4908 llvm_unreachable("Invalid EvalStmtResult!");
4909 }
4910
4911 /// Evaluate a switch statement.
EvaluateSwitch(StmtResult & Result,EvalInfo & Info,const SwitchStmt * SS)4912 static EvalStmtResult EvaluateSwitch(StmtResult &Result, EvalInfo &Info,
4913 const SwitchStmt *SS) {
4914 BlockScopeRAII Scope(Info);
4915
4916 // Evaluate the switch condition.
4917 APSInt Value;
4918 {
4919 if (const Stmt *Init = SS->getInit()) {
4920 EvalStmtResult ESR = EvaluateStmt(Result, Info, Init);
4921 if (ESR != ESR_Succeeded) {
4922 if (ESR != ESR_Failed && !Scope.destroy())
4923 ESR = ESR_Failed;
4924 return ESR;
4925 }
4926 }
4927
4928 FullExpressionRAII CondScope(Info);
4929 if (SS->getConditionVariable() &&
4930 !EvaluateDecl(Info, SS->getConditionVariable()))
4931 return ESR_Failed;
4932 if (!EvaluateInteger(SS->getCond(), Value, Info))
4933 return ESR_Failed;
4934 if (!CondScope.destroy())
4935 return ESR_Failed;
4936 }
4937
4938 // Find the switch case corresponding to the value of the condition.
4939 // FIXME: Cache this lookup.
4940 const SwitchCase *Found = nullptr;
4941 for (const SwitchCase *SC = SS->getSwitchCaseList(); SC;
4942 SC = SC->getNextSwitchCase()) {
4943 if (isa<DefaultStmt>(SC)) {
4944 Found = SC;
4945 continue;
4946 }
4947
4948 const CaseStmt *CS = cast<CaseStmt>(SC);
4949 APSInt LHS = CS->getLHS()->EvaluateKnownConstInt(Info.Ctx);
4950 APSInt RHS = CS->getRHS() ? CS->getRHS()->EvaluateKnownConstInt(Info.Ctx)
4951 : LHS;
4952 if (LHS <= Value && Value <= RHS) {
4953 Found = SC;
4954 break;
4955 }
4956 }
4957
4958 if (!Found)
4959 return Scope.destroy() ? ESR_Succeeded : ESR_Failed;
4960
4961 // Search the switch body for the switch case and evaluate it from there.
4962 EvalStmtResult ESR = EvaluateStmt(Result, Info, SS->getBody(), Found);
4963 if (ESR != ESR_Failed && ESR != ESR_CaseNotFound && !Scope.destroy())
4964 return ESR_Failed;
4965
4966 switch (ESR) {
4967 case ESR_Break:
4968 return ESR_Succeeded;
4969 case ESR_Succeeded:
4970 case ESR_Continue:
4971 case ESR_Failed:
4972 case ESR_Returned:
4973 return ESR;
4974 case ESR_CaseNotFound:
4975 // This can only happen if the switch case is nested within a statement
4976 // expression. We have no intention of supporting that.
4977 Info.FFDiag(Found->getBeginLoc(),
4978 diag::note_constexpr_stmt_expr_unsupported);
4979 return ESR_Failed;
4980 }
4981 llvm_unreachable("Invalid EvalStmtResult!");
4982 }
4983
4984 // Evaluate a statement.
EvaluateStmt(StmtResult & Result,EvalInfo & Info,const Stmt * S,const SwitchCase * Case)4985 static EvalStmtResult EvaluateStmt(StmtResult &Result, EvalInfo &Info,
4986 const Stmt *S, const SwitchCase *Case) {
4987 if (!Info.nextStep(S))
4988 return ESR_Failed;
4989
4990 // If we're hunting down a 'case' or 'default' label, recurse through
4991 // substatements until we hit the label.
4992 if (Case) {
4993 switch (S->getStmtClass()) {
4994 case Stmt::CompoundStmtClass:
4995 // FIXME: Precompute which substatement of a compound statement we
4996 // would jump to, and go straight there rather than performing a
4997 // linear scan each time.
4998 case Stmt::LabelStmtClass:
4999 case Stmt::AttributedStmtClass:
5000 case Stmt::DoStmtClass:
5001 break;
5002
5003 case Stmt::CaseStmtClass:
5004 case Stmt::DefaultStmtClass:
5005 if (Case == S)
5006 Case = nullptr;
5007 break;
5008
5009 case Stmt::IfStmtClass: {
5010 // FIXME: Precompute which side of an 'if' we would jump to, and go
5011 // straight there rather than scanning both sides.
5012 const IfStmt *IS = cast<IfStmt>(S);
5013
5014 // Wrap the evaluation in a block scope, in case it's a DeclStmt
5015 // preceded by our switch label.
5016 BlockScopeRAII Scope(Info);
5017
5018 // Step into the init statement in case it brings an (uninitialized)
5019 // variable into scope.
5020 if (const Stmt *Init = IS->getInit()) {
5021 EvalStmtResult ESR = EvaluateStmt(Result, Info, Init, Case);
5022 if (ESR != ESR_CaseNotFound) {
5023 assert(ESR != ESR_Succeeded);
5024 return ESR;
5025 }
5026 }
5027
5028 // Condition variable must be initialized if it exists.
5029 // FIXME: We can skip evaluating the body if there's a condition
5030 // variable, as there can't be any case labels within it.
5031 // (The same is true for 'for' statements.)
5032
5033 EvalStmtResult ESR = EvaluateStmt(Result, Info, IS->getThen(), Case);
5034 if (ESR == ESR_Failed)
5035 return ESR;
5036 if (ESR != ESR_CaseNotFound)
5037 return Scope.destroy() ? ESR : ESR_Failed;
5038 if (!IS->getElse())
5039 return ESR_CaseNotFound;
5040
5041 ESR = EvaluateStmt(Result, Info, IS->getElse(), Case);
5042 if (ESR == ESR_Failed)
5043 return ESR;
5044 if (ESR != ESR_CaseNotFound)
5045 return Scope.destroy() ? ESR : ESR_Failed;
5046 return ESR_CaseNotFound;
5047 }
5048
5049 case Stmt::WhileStmtClass: {
5050 EvalStmtResult ESR =
5051 EvaluateLoopBody(Result, Info, cast<WhileStmt>(S)->getBody(), Case);
5052 if (ESR != ESR_Continue)
5053 return ESR;
5054 break;
5055 }
5056
5057 case Stmt::ForStmtClass: {
5058 const ForStmt *FS = cast<ForStmt>(S);
5059 BlockScopeRAII Scope(Info);
5060
5061 // Step into the init statement in case it brings an (uninitialized)
5062 // variable into scope.
5063 if (const Stmt *Init = FS->getInit()) {
5064 EvalStmtResult ESR = EvaluateStmt(Result, Info, Init, Case);
5065 if (ESR != ESR_CaseNotFound) {
5066 assert(ESR != ESR_Succeeded);
5067 return ESR;
5068 }
5069 }
5070
5071 EvalStmtResult ESR =
5072 EvaluateLoopBody(Result, Info, FS->getBody(), Case);
5073 if (ESR != ESR_Continue)
5074 return ESR;
5075 if (const auto *Inc = FS->getInc()) {
5076 if (Inc->isValueDependent()) {
5077 if (!EvaluateDependentExpr(Inc, Info))
5078 return ESR_Failed;
5079 } else {
5080 FullExpressionRAII IncScope(Info);
5081 if (!EvaluateIgnoredValue(Info, Inc) || !IncScope.destroy())
5082 return ESR_Failed;
5083 }
5084 }
5085 break;
5086 }
5087
5088 case Stmt::DeclStmtClass: {
5089 // Start the lifetime of any uninitialized variables we encounter. They
5090 // might be used by the selected branch of the switch.
5091 const DeclStmt *DS = cast<DeclStmt>(S);
5092 for (const auto *D : DS->decls()) {
5093 if (const auto *VD = dyn_cast<VarDecl>(D)) {
5094 if (VD->hasLocalStorage() && !VD->getInit())
5095 if (!EvaluateVarDecl(Info, VD))
5096 return ESR_Failed;
5097 // FIXME: If the variable has initialization that can't be jumped
5098 // over, bail out of any immediately-surrounding compound-statement
5099 // too. There can't be any case labels here.
5100 }
5101 }
5102 return ESR_CaseNotFound;
5103 }
5104
5105 default:
5106 return ESR_CaseNotFound;
5107 }
5108 }
5109
5110 switch (S->getStmtClass()) {
5111 default:
5112 if (const Expr *E = dyn_cast<Expr>(S)) {
5113 if (E->isValueDependent()) {
5114 if (!EvaluateDependentExpr(E, Info))
5115 return ESR_Failed;
5116 } else {
5117 // Don't bother evaluating beyond an expression-statement which couldn't
5118 // be evaluated.
5119 // FIXME: Do we need the FullExpressionRAII object here?
5120 // VisitExprWithCleanups should create one when necessary.
5121 FullExpressionRAII Scope(Info);
5122 if (!EvaluateIgnoredValue(Info, E) || !Scope.destroy())
5123 return ESR_Failed;
5124 }
5125 return ESR_Succeeded;
5126 }
5127
5128 Info.FFDiag(S->getBeginLoc());
5129 return ESR_Failed;
5130
5131 case Stmt::NullStmtClass:
5132 return ESR_Succeeded;
5133
5134 case Stmt::DeclStmtClass: {
5135 const DeclStmt *DS = cast<DeclStmt>(S);
5136 for (const auto *D : DS->decls()) {
5137 // Each declaration initialization is its own full-expression.
5138 FullExpressionRAII Scope(Info);
5139 if (!EvaluateDecl(Info, D) && !Info.noteFailure())
5140 return ESR_Failed;
5141 if (!Scope.destroy())
5142 return ESR_Failed;
5143 }
5144 return ESR_Succeeded;
5145 }
5146
5147 case Stmt::ReturnStmtClass: {
5148 const Expr *RetExpr = cast<ReturnStmt>(S)->getRetValue();
5149 FullExpressionRAII Scope(Info);
5150 if (RetExpr && RetExpr->isValueDependent()) {
5151 EvaluateDependentExpr(RetExpr, Info);
5152 // We know we returned, but we don't know what the value is.
5153 return ESR_Failed;
5154 }
5155 if (RetExpr &&
5156 !(Result.Slot
5157 ? EvaluateInPlace(Result.Value, Info, *Result.Slot, RetExpr)
5158 : Evaluate(Result.Value, Info, RetExpr)))
5159 return ESR_Failed;
5160 return Scope.destroy() ? ESR_Returned : ESR_Failed;
5161 }
5162
5163 case Stmt::CompoundStmtClass: {
5164 BlockScopeRAII Scope(Info);
5165
5166 const CompoundStmt *CS = cast<CompoundStmt>(S);
5167 for (const auto *BI : CS->body()) {
5168 EvalStmtResult ESR = EvaluateStmt(Result, Info, BI, Case);
5169 if (ESR == ESR_Succeeded)
5170 Case = nullptr;
5171 else if (ESR != ESR_CaseNotFound) {
5172 if (ESR != ESR_Failed && !Scope.destroy())
5173 return ESR_Failed;
5174 return ESR;
5175 }
5176 }
5177 if (Case)
5178 return ESR_CaseNotFound;
5179 return Scope.destroy() ? ESR_Succeeded : ESR_Failed;
5180 }
5181
5182 case Stmt::IfStmtClass: {
5183 const IfStmt *IS = cast<IfStmt>(S);
5184
5185 // Evaluate the condition, as either a var decl or as an expression.
5186 BlockScopeRAII Scope(Info);
5187 if (const Stmt *Init = IS->getInit()) {
5188 EvalStmtResult ESR = EvaluateStmt(Result, Info, Init);
5189 if (ESR != ESR_Succeeded) {
5190 if (ESR != ESR_Failed && !Scope.destroy())
5191 return ESR_Failed;
5192 return ESR;
5193 }
5194 }
5195 bool Cond;
5196 if (!EvaluateCond(Info, IS->getConditionVariable(), IS->getCond(), Cond))
5197 return ESR_Failed;
5198
5199 if (const Stmt *SubStmt = Cond ? IS->getThen() : IS->getElse()) {
5200 EvalStmtResult ESR = EvaluateStmt(Result, Info, SubStmt);
5201 if (ESR != ESR_Succeeded) {
5202 if (ESR != ESR_Failed && !Scope.destroy())
5203 return ESR_Failed;
5204 return ESR;
5205 }
5206 }
5207 return Scope.destroy() ? ESR_Succeeded : ESR_Failed;
5208 }
5209
5210 case Stmt::WhileStmtClass: {
5211 const WhileStmt *WS = cast<WhileStmt>(S);
5212 while (true) {
5213 BlockScopeRAII Scope(Info);
5214 bool Continue;
5215 if (!EvaluateCond(Info, WS->getConditionVariable(), WS->getCond(),
5216 Continue))
5217 return ESR_Failed;
5218 if (!Continue)
5219 break;
5220
5221 EvalStmtResult ESR = EvaluateLoopBody(Result, Info, WS->getBody());
5222 if (ESR != ESR_Continue) {
5223 if (ESR != ESR_Failed && !Scope.destroy())
5224 return ESR_Failed;
5225 return ESR;
5226 }
5227 if (!Scope.destroy())
5228 return ESR_Failed;
5229 }
5230 return ESR_Succeeded;
5231 }
5232
5233 case Stmt::DoStmtClass: {
5234 const DoStmt *DS = cast<DoStmt>(S);
5235 bool Continue;
5236 do {
5237 EvalStmtResult ESR = EvaluateLoopBody(Result, Info, DS->getBody(), Case);
5238 if (ESR != ESR_Continue)
5239 return ESR;
5240 Case = nullptr;
5241
5242 if (DS->getCond()->isValueDependent()) {
5243 EvaluateDependentExpr(DS->getCond(), Info);
5244 // Bailout as we don't know whether to keep going or terminate the loop.
5245 return ESR_Failed;
5246 }
5247 FullExpressionRAII CondScope(Info);
5248 if (!EvaluateAsBooleanCondition(DS->getCond(), Continue, Info) ||
5249 !CondScope.destroy())
5250 return ESR_Failed;
5251 } while (Continue);
5252 return ESR_Succeeded;
5253 }
5254
5255 case Stmt::ForStmtClass: {
5256 const ForStmt *FS = cast<ForStmt>(S);
5257 BlockScopeRAII ForScope(Info);
5258 if (FS->getInit()) {
5259 EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getInit());
5260 if (ESR != ESR_Succeeded) {
5261 if (ESR != ESR_Failed && !ForScope.destroy())
5262 return ESR_Failed;
5263 return ESR;
5264 }
5265 }
5266 while (true) {
5267 BlockScopeRAII IterScope(Info);
5268 bool Continue = true;
5269 if (FS->getCond() && !EvaluateCond(Info, FS->getConditionVariable(),
5270 FS->getCond(), Continue))
5271 return ESR_Failed;
5272 if (!Continue)
5273 break;
5274
5275 EvalStmtResult ESR = EvaluateLoopBody(Result, Info, FS->getBody());
5276 if (ESR != ESR_Continue) {
5277 if (ESR != ESR_Failed && (!IterScope.destroy() || !ForScope.destroy()))
5278 return ESR_Failed;
5279 return ESR;
5280 }
5281
5282 if (const auto *Inc = FS->getInc()) {
5283 if (Inc->isValueDependent()) {
5284 if (!EvaluateDependentExpr(Inc, Info))
5285 return ESR_Failed;
5286 } else {
5287 FullExpressionRAII IncScope(Info);
5288 if (!EvaluateIgnoredValue(Info, Inc) || !IncScope.destroy())
5289 return ESR_Failed;
5290 }
5291 }
5292
5293 if (!IterScope.destroy())
5294 return ESR_Failed;
5295 }
5296 return ForScope.destroy() ? ESR_Succeeded : ESR_Failed;
5297 }
5298
5299 case Stmt::CXXForRangeStmtClass: {
5300 const CXXForRangeStmt *FS = cast<CXXForRangeStmt>(S);
5301 BlockScopeRAII Scope(Info);
5302
5303 // Evaluate the init-statement if present.
5304 if (FS->getInit()) {
5305 EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getInit());
5306 if (ESR != ESR_Succeeded) {
5307 if (ESR != ESR_Failed && !Scope.destroy())
5308 return ESR_Failed;
5309 return ESR;
5310 }
5311 }
5312
5313 // Initialize the __range variable.
5314 EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getRangeStmt());
5315 if (ESR != ESR_Succeeded) {
5316 if (ESR != ESR_Failed && !Scope.destroy())
5317 return ESR_Failed;
5318 return ESR;
5319 }
5320
5321 // Create the __begin and __end iterators.
5322 ESR = EvaluateStmt(Result, Info, FS->getBeginStmt());
5323 if (ESR != ESR_Succeeded) {
5324 if (ESR != ESR_Failed && !Scope.destroy())
5325 return ESR_Failed;
5326 return ESR;
5327 }
5328 ESR = EvaluateStmt(Result, Info, FS->getEndStmt());
5329 if (ESR != ESR_Succeeded) {
5330 if (ESR != ESR_Failed && !Scope.destroy())
5331 return ESR_Failed;
5332 return ESR;
5333 }
5334
5335 while (true) {
5336 // Condition: __begin != __end.
5337 {
5338 if (FS->getCond()->isValueDependent()) {
5339 EvaluateDependentExpr(FS->getCond(), Info);
5340 // We don't know whether to keep going or terminate the loop.
5341 return ESR_Failed;
5342 }
5343 bool Continue = true;
5344 FullExpressionRAII CondExpr(Info);
5345 if (!EvaluateAsBooleanCondition(FS->getCond(), Continue, Info))
5346 return ESR_Failed;
5347 if (!Continue)
5348 break;
5349 }
5350
5351 // User's variable declaration, initialized by *__begin.
5352 BlockScopeRAII InnerScope(Info);
5353 ESR = EvaluateStmt(Result, Info, FS->getLoopVarStmt());
5354 if (ESR != ESR_Succeeded) {
5355 if (ESR != ESR_Failed && (!InnerScope.destroy() || !Scope.destroy()))
5356 return ESR_Failed;
5357 return ESR;
5358 }
5359
5360 // Loop body.
5361 ESR = EvaluateLoopBody(Result, Info, FS->getBody());
5362 if (ESR != ESR_Continue) {
5363 if (ESR != ESR_Failed && (!InnerScope.destroy() || !Scope.destroy()))
5364 return ESR_Failed;
5365 return ESR;
5366 }
5367 if (FS->getInc()->isValueDependent()) {
5368 if (!EvaluateDependentExpr(FS->getInc(), Info))
5369 return ESR_Failed;
5370 } else {
5371 // Increment: ++__begin
5372 if (!EvaluateIgnoredValue(Info, FS->getInc()))
5373 return ESR_Failed;
5374 }
5375
5376 if (!InnerScope.destroy())
5377 return ESR_Failed;
5378 }
5379
5380 return Scope.destroy() ? ESR_Succeeded : ESR_Failed;
5381 }
5382
5383 case Stmt::SwitchStmtClass:
5384 return EvaluateSwitch(Result, Info, cast<SwitchStmt>(S));
5385
5386 case Stmt::ContinueStmtClass:
5387 return ESR_Continue;
5388
5389 case Stmt::BreakStmtClass:
5390 return ESR_Break;
5391
5392 case Stmt::LabelStmtClass:
5393 return EvaluateStmt(Result, Info, cast<LabelStmt>(S)->getSubStmt(), Case);
5394
5395 case Stmt::AttributedStmtClass:
5396 // As a general principle, C++11 attributes can be ignored without
5397 // any semantic impact.
5398 return EvaluateStmt(Result, Info, cast<AttributedStmt>(S)->getSubStmt(),
5399 Case);
5400
5401 case Stmt::CaseStmtClass:
5402 case Stmt::DefaultStmtClass:
5403 return EvaluateStmt(Result, Info, cast<SwitchCase>(S)->getSubStmt(), Case);
5404 case Stmt::CXXTryStmtClass:
5405 // Evaluate try blocks by evaluating all sub statements.
5406 return EvaluateStmt(Result, Info, cast<CXXTryStmt>(S)->getTryBlock(), Case);
5407 }
5408 }
5409
5410 /// CheckTrivialDefaultConstructor - Check whether a constructor is a trivial
5411 /// default constructor. If so, we'll fold it whether or not it's marked as
5412 /// constexpr. If it is marked as constexpr, we will never implicitly define it,
5413 /// so we need special handling.
CheckTrivialDefaultConstructor(EvalInfo & Info,SourceLocation Loc,const CXXConstructorDecl * CD,bool IsValueInitialization)5414 static bool CheckTrivialDefaultConstructor(EvalInfo &Info, SourceLocation Loc,
5415 const CXXConstructorDecl *CD,
5416 bool IsValueInitialization) {
5417 if (!CD->isTrivial() || !CD->isDefaultConstructor())
5418 return false;
5419
5420 // Value-initialization does not call a trivial default constructor, so such a
5421 // call is a core constant expression whether or not the constructor is
5422 // constexpr.
5423 if (!CD->isConstexpr() && !IsValueInitialization) {
5424 if (Info.getLangOpts().CPlusPlus11) {
5425 // FIXME: If DiagDecl is an implicitly-declared special member function,
5426 // we should be much more explicit about why it's not constexpr.
5427 Info.CCEDiag(Loc, diag::note_constexpr_invalid_function, 1)
5428 << /*IsConstexpr*/0 << /*IsConstructor*/1 << CD;
5429 Info.Note(CD->getLocation(), diag::note_declared_at);
5430 } else {
5431 Info.CCEDiag(Loc, diag::note_invalid_subexpr_in_const_expr);
5432 }
5433 }
5434 return true;
5435 }
5436
5437 /// CheckConstexprFunction - Check that a function can be called in a constant
5438 /// expression.
CheckConstexprFunction(EvalInfo & Info,SourceLocation CallLoc,const FunctionDecl * Declaration,const FunctionDecl * Definition,const Stmt * Body)5439 static bool CheckConstexprFunction(EvalInfo &Info, SourceLocation CallLoc,
5440 const FunctionDecl *Declaration,
5441 const FunctionDecl *Definition,
5442 const Stmt *Body) {
5443 // Potential constant expressions can contain calls to declared, but not yet
5444 // defined, constexpr functions.
5445 if (Info.checkingPotentialConstantExpression() && !Definition &&
5446 Declaration->isConstexpr())
5447 return false;
5448
5449 // Bail out if the function declaration itself is invalid. We will
5450 // have produced a relevant diagnostic while parsing it, so just
5451 // note the problematic sub-expression.
5452 if (Declaration->isInvalidDecl()) {
5453 Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr);
5454 return false;
5455 }
5456
5457 // DR1872: An instantiated virtual constexpr function can't be called in a
5458 // constant expression (prior to C++20). We can still constant-fold such a
5459 // call.
5460 if (!Info.Ctx.getLangOpts().CPlusPlus20 && isa<CXXMethodDecl>(Declaration) &&
5461 cast<CXXMethodDecl>(Declaration)->isVirtual())
5462 Info.CCEDiag(CallLoc, diag::note_constexpr_virtual_call);
5463
5464 if (Definition && Definition->isInvalidDecl()) {
5465 Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr);
5466 return false;
5467 }
5468
5469 // Can we evaluate this function call?
5470 if (Definition && Definition->isConstexpr() && Body)
5471 return true;
5472
5473 if (Info.getLangOpts().CPlusPlus11) {
5474 const FunctionDecl *DiagDecl = Definition ? Definition : Declaration;
5475
5476 // If this function is not constexpr because it is an inherited
5477 // non-constexpr constructor, diagnose that directly.
5478 auto *CD = dyn_cast<CXXConstructorDecl>(DiagDecl);
5479 if (CD && CD->isInheritingConstructor()) {
5480 auto *Inherited = CD->getInheritedConstructor().getConstructor();
5481 if (!Inherited->isConstexpr())
5482 DiagDecl = CD = Inherited;
5483 }
5484
5485 // FIXME: If DiagDecl is an implicitly-declared special member function
5486 // or an inheriting constructor, we should be much more explicit about why
5487 // it's not constexpr.
5488 if (CD && CD->isInheritingConstructor())
5489 Info.FFDiag(CallLoc, diag::note_constexpr_invalid_inhctor, 1)
5490 << CD->getInheritedConstructor().getConstructor()->getParent();
5491 else
5492 Info.FFDiag(CallLoc, diag::note_constexpr_invalid_function, 1)
5493 << DiagDecl->isConstexpr() << (bool)CD << DiagDecl;
5494 Info.Note(DiagDecl->getLocation(), diag::note_declared_at);
5495 } else {
5496 Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr);
5497 }
5498 return false;
5499 }
5500
5501 namespace {
5502 struct CheckDynamicTypeHandler {
5503 AccessKinds AccessKind;
5504 typedef bool result_type;
failed__anon6b379bbb1011::CheckDynamicTypeHandler5505 bool failed() { return false; }
found__anon6b379bbb1011::CheckDynamicTypeHandler5506 bool found(APValue &Subobj, QualType SubobjType) { return true; }
found__anon6b379bbb1011::CheckDynamicTypeHandler5507 bool found(APSInt &Value, QualType SubobjType) { return true; }
found__anon6b379bbb1011::CheckDynamicTypeHandler5508 bool found(APFloat &Value, QualType SubobjType) { return true; }
5509 };
5510 } // end anonymous namespace
5511
5512 /// Check that we can access the notional vptr of an object / determine its
5513 /// dynamic type.
checkDynamicType(EvalInfo & Info,const Expr * E,const LValue & This,AccessKinds AK,bool Polymorphic)5514 static bool checkDynamicType(EvalInfo &Info, const Expr *E, const LValue &This,
5515 AccessKinds AK, bool Polymorphic) {
5516 if (This.Designator.Invalid)
5517 return false;
5518
5519 CompleteObject Obj = findCompleteObject(Info, E, AK, This, QualType());
5520
5521 if (!Obj)
5522 return false;
5523
5524 if (!Obj.Value) {
5525 // The object is not usable in constant expressions, so we can't inspect
5526 // its value to see if it's in-lifetime or what the active union members
5527 // are. We can still check for a one-past-the-end lvalue.
5528 if (This.Designator.isOnePastTheEnd() ||
5529 This.Designator.isMostDerivedAnUnsizedArray()) {
5530 Info.FFDiag(E, This.Designator.isOnePastTheEnd()
5531 ? diag::note_constexpr_access_past_end
5532 : diag::note_constexpr_access_unsized_array)
5533 << AK;
5534 return false;
5535 } else if (Polymorphic) {
5536 // Conservatively refuse to perform a polymorphic operation if we would
5537 // not be able to read a notional 'vptr' value.
5538 APValue Val;
5539 This.moveInto(Val);
5540 QualType StarThisType =
5541 Info.Ctx.getLValueReferenceType(This.Designator.getType(Info.Ctx));
5542 Info.FFDiag(E, diag::note_constexpr_polymorphic_unknown_dynamic_type)
5543 << AK << Val.getAsString(Info.Ctx, StarThisType);
5544 return false;
5545 }
5546 return true;
5547 }
5548
5549 CheckDynamicTypeHandler Handler{AK};
5550 return Obj && findSubobject(Info, E, Obj, This.Designator, Handler);
5551 }
5552
5553 /// Check that the pointee of the 'this' pointer in a member function call is
5554 /// either within its lifetime or in its period of construction or destruction.
5555 static bool
checkNonVirtualMemberCallThisPointer(EvalInfo & Info,const Expr * E,const LValue & This,const CXXMethodDecl * NamedMember)5556 checkNonVirtualMemberCallThisPointer(EvalInfo &Info, const Expr *E,
5557 const LValue &This,
5558 const CXXMethodDecl *NamedMember) {
5559 return checkDynamicType(
5560 Info, E, This,
5561 isa<CXXDestructorDecl>(NamedMember) ? AK_Destroy : AK_MemberCall, false);
5562 }
5563
5564 struct DynamicType {
5565 /// The dynamic class type of the object.
5566 const CXXRecordDecl *Type;
5567 /// The corresponding path length in the lvalue.
5568 unsigned PathLength;
5569 };
5570
getBaseClassType(SubobjectDesignator & Designator,unsigned PathLength)5571 static const CXXRecordDecl *getBaseClassType(SubobjectDesignator &Designator,
5572 unsigned PathLength) {
5573 assert(PathLength >= Designator.MostDerivedPathLength && PathLength <=
5574 Designator.Entries.size() && "invalid path length");
5575 return (PathLength == Designator.MostDerivedPathLength)
5576 ? Designator.MostDerivedType->getAsCXXRecordDecl()
5577 : getAsBaseClass(Designator.Entries[PathLength - 1]);
5578 }
5579
5580 /// Determine the dynamic type of an object.
ComputeDynamicType(EvalInfo & Info,const Expr * E,LValue & This,AccessKinds AK)5581 static Optional<DynamicType> ComputeDynamicType(EvalInfo &Info, const Expr *E,
5582 LValue &This, AccessKinds AK) {
5583 // If we don't have an lvalue denoting an object of class type, there is no
5584 // meaningful dynamic type. (We consider objects of non-class type to have no
5585 // dynamic type.)
5586 if (!checkDynamicType(Info, E, This, AK, true))
5587 return None;
5588
5589 // Refuse to compute a dynamic type in the presence of virtual bases. This
5590 // shouldn't happen other than in constant-folding situations, since literal
5591 // types can't have virtual bases.
5592 //
5593 // Note that consumers of DynamicType assume that the type has no virtual
5594 // bases, and will need modifications if this restriction is relaxed.
5595 const CXXRecordDecl *Class =
5596 This.Designator.MostDerivedType->getAsCXXRecordDecl();
5597 if (!Class || Class->getNumVBases()) {
5598 Info.FFDiag(E);
5599 return None;
5600 }
5601
5602 // FIXME: For very deep class hierarchies, it might be beneficial to use a
5603 // binary search here instead. But the overwhelmingly common case is that
5604 // we're not in the middle of a constructor, so it probably doesn't matter
5605 // in practice.
5606 ArrayRef<APValue::LValuePathEntry> Path = This.Designator.Entries;
5607 for (unsigned PathLength = This.Designator.MostDerivedPathLength;
5608 PathLength <= Path.size(); ++PathLength) {
5609 switch (Info.isEvaluatingCtorDtor(This.getLValueBase(),
5610 Path.slice(0, PathLength))) {
5611 case ConstructionPhase::Bases:
5612 case ConstructionPhase::DestroyingBases:
5613 // We're constructing or destroying a base class. This is not the dynamic
5614 // type.
5615 break;
5616
5617 case ConstructionPhase::None:
5618 case ConstructionPhase::AfterBases:
5619 case ConstructionPhase::AfterFields:
5620 case ConstructionPhase::Destroying:
5621 // We've finished constructing the base classes and not yet started
5622 // destroying them again, so this is the dynamic type.
5623 return DynamicType{getBaseClassType(This.Designator, PathLength),
5624 PathLength};
5625 }
5626 }
5627
5628 // CWG issue 1517: we're constructing a base class of the object described by
5629 // 'This', so that object has not yet begun its period of construction and
5630 // any polymorphic operation on it results in undefined behavior.
5631 Info.FFDiag(E);
5632 return None;
5633 }
5634
5635 /// Perform virtual dispatch.
HandleVirtualDispatch(EvalInfo & Info,const Expr * E,LValue & This,const CXXMethodDecl * Found,llvm::SmallVectorImpl<QualType> & CovariantAdjustmentPath)5636 static const CXXMethodDecl *HandleVirtualDispatch(
5637 EvalInfo &Info, const Expr *E, LValue &This, const CXXMethodDecl *Found,
5638 llvm::SmallVectorImpl<QualType> &CovariantAdjustmentPath) {
5639 Optional<DynamicType> DynType = ComputeDynamicType(
5640 Info, E, This,
5641 isa<CXXDestructorDecl>(Found) ? AK_Destroy : AK_MemberCall);
5642 if (!DynType)
5643 return nullptr;
5644
5645 // Find the final overrider. It must be declared in one of the classes on the
5646 // path from the dynamic type to the static type.
5647 // FIXME: If we ever allow literal types to have virtual base classes, that
5648 // won't be true.
5649 const CXXMethodDecl *Callee = Found;
5650 unsigned PathLength = DynType->PathLength;
5651 for (/**/; PathLength <= This.Designator.Entries.size(); ++PathLength) {
5652 const CXXRecordDecl *Class = getBaseClassType(This.Designator, PathLength);
5653 const CXXMethodDecl *Overrider =
5654 Found->getCorrespondingMethodDeclaredInClass(Class, false);
5655 if (Overrider) {
5656 Callee = Overrider;
5657 break;
5658 }
5659 }
5660
5661 // C++2a [class.abstract]p6:
5662 // the effect of making a virtual call to a pure virtual function [...] is
5663 // undefined
5664 if (Callee->isPure()) {
5665 Info.FFDiag(E, diag::note_constexpr_pure_virtual_call, 1) << Callee;
5666 Info.Note(Callee->getLocation(), diag::note_declared_at);
5667 return nullptr;
5668 }
5669
5670 // If necessary, walk the rest of the path to determine the sequence of
5671 // covariant adjustment steps to apply.
5672 if (!Info.Ctx.hasSameUnqualifiedType(Callee->getReturnType(),
5673 Found->getReturnType())) {
5674 CovariantAdjustmentPath.push_back(Callee->getReturnType());
5675 for (unsigned CovariantPathLength = PathLength + 1;
5676 CovariantPathLength != This.Designator.Entries.size();
5677 ++CovariantPathLength) {
5678 const CXXRecordDecl *NextClass =
5679 getBaseClassType(This.Designator, CovariantPathLength);
5680 const CXXMethodDecl *Next =
5681 Found->getCorrespondingMethodDeclaredInClass(NextClass, false);
5682 if (Next && !Info.Ctx.hasSameUnqualifiedType(
5683 Next->getReturnType(), CovariantAdjustmentPath.back()))
5684 CovariantAdjustmentPath.push_back(Next->getReturnType());
5685 }
5686 if (!Info.Ctx.hasSameUnqualifiedType(Found->getReturnType(),
5687 CovariantAdjustmentPath.back()))
5688 CovariantAdjustmentPath.push_back(Found->getReturnType());
5689 }
5690
5691 // Perform 'this' adjustment.
5692 if (!CastToDerivedClass(Info, E, This, Callee->getParent(), PathLength))
5693 return nullptr;
5694
5695 return Callee;
5696 }
5697
5698 /// Perform the adjustment from a value returned by a virtual function to
5699 /// a value of the statically expected type, which may be a pointer or
5700 /// reference to a base class of the returned type.
HandleCovariantReturnAdjustment(EvalInfo & Info,const Expr * E,APValue & Result,ArrayRef<QualType> Path)5701 static bool HandleCovariantReturnAdjustment(EvalInfo &Info, const Expr *E,
5702 APValue &Result,
5703 ArrayRef<QualType> Path) {
5704 assert(Result.isLValue() &&
5705 "unexpected kind of APValue for covariant return");
5706 if (Result.isNullPointer())
5707 return true;
5708
5709 LValue LVal;
5710 LVal.setFrom(Info.Ctx, Result);
5711
5712 const CXXRecordDecl *OldClass = Path[0]->getPointeeCXXRecordDecl();
5713 for (unsigned I = 1; I != Path.size(); ++I) {
5714 const CXXRecordDecl *NewClass = Path[I]->getPointeeCXXRecordDecl();
5715 assert(OldClass && NewClass && "unexpected kind of covariant return");
5716 if (OldClass != NewClass &&
5717 !CastToBaseClass(Info, E, LVal, OldClass, NewClass))
5718 return false;
5719 OldClass = NewClass;
5720 }
5721
5722 LVal.moveInto(Result);
5723 return true;
5724 }
5725
5726 /// Determine whether \p Base, which is known to be a direct base class of
5727 /// \p Derived, is a public base class.
isBaseClassPublic(const CXXRecordDecl * Derived,const CXXRecordDecl * Base)5728 static bool isBaseClassPublic(const CXXRecordDecl *Derived,
5729 const CXXRecordDecl *Base) {
5730 for (const CXXBaseSpecifier &BaseSpec : Derived->bases()) {
5731 auto *BaseClass = BaseSpec.getType()->getAsCXXRecordDecl();
5732 if (BaseClass && declaresSameEntity(BaseClass, Base))
5733 return BaseSpec.getAccessSpecifier() == AS_public;
5734 }
5735 llvm_unreachable("Base is not a direct base of Derived");
5736 }
5737
5738 /// Apply the given dynamic cast operation on the provided lvalue.
5739 ///
5740 /// This implements the hard case of dynamic_cast, requiring a "runtime check"
5741 /// to find a suitable target subobject.
HandleDynamicCast(EvalInfo & Info,const ExplicitCastExpr * E,LValue & Ptr)5742 static bool HandleDynamicCast(EvalInfo &Info, const ExplicitCastExpr *E,
5743 LValue &Ptr) {
5744 // We can't do anything with a non-symbolic pointer value.
5745 SubobjectDesignator &D = Ptr.Designator;
5746 if (D.Invalid)
5747 return false;
5748
5749 // C++ [expr.dynamic.cast]p6:
5750 // If v is a null pointer value, the result is a null pointer value.
5751 if (Ptr.isNullPointer() && !E->isGLValue())
5752 return true;
5753
5754 // For all the other cases, we need the pointer to point to an object within
5755 // its lifetime / period of construction / destruction, and we need to know
5756 // its dynamic type.
5757 Optional<DynamicType> DynType =
5758 ComputeDynamicType(Info, E, Ptr, AK_DynamicCast);
5759 if (!DynType)
5760 return false;
5761
5762 // C++ [expr.dynamic.cast]p7:
5763 // If T is "pointer to cv void", then the result is a pointer to the most
5764 // derived object
5765 if (E->getType()->isVoidPointerType())
5766 return CastToDerivedClass(Info, E, Ptr, DynType->Type, DynType->PathLength);
5767
5768 const CXXRecordDecl *C = E->getTypeAsWritten()->getPointeeCXXRecordDecl();
5769 assert(C && "dynamic_cast target is not void pointer nor class");
5770 CanQualType CQT = Info.Ctx.getCanonicalType(Info.Ctx.getRecordType(C));
5771
5772 auto RuntimeCheckFailed = [&] (CXXBasePaths *Paths) {
5773 // C++ [expr.dynamic.cast]p9:
5774 if (!E->isGLValue()) {
5775 // The value of a failed cast to pointer type is the null pointer value
5776 // of the required result type.
5777 Ptr.setNull(Info.Ctx, E->getType());
5778 return true;
5779 }
5780
5781 // A failed cast to reference type throws [...] std::bad_cast.
5782 unsigned DiagKind;
5783 if (!Paths && (declaresSameEntity(DynType->Type, C) ||
5784 DynType->Type->isDerivedFrom(C)))
5785 DiagKind = 0;
5786 else if (!Paths || Paths->begin() == Paths->end())
5787 DiagKind = 1;
5788 else if (Paths->isAmbiguous(CQT))
5789 DiagKind = 2;
5790 else {
5791 assert(Paths->front().Access != AS_public && "why did the cast fail?");
5792 DiagKind = 3;
5793 }
5794 Info.FFDiag(E, diag::note_constexpr_dynamic_cast_to_reference_failed)
5795 << DiagKind << Ptr.Designator.getType(Info.Ctx)
5796 << Info.Ctx.getRecordType(DynType->Type)
5797 << E->getType().getUnqualifiedType();
5798 return false;
5799 };
5800
5801 // Runtime check, phase 1:
5802 // Walk from the base subobject towards the derived object looking for the
5803 // target type.
5804 for (int PathLength = Ptr.Designator.Entries.size();
5805 PathLength >= (int)DynType->PathLength; --PathLength) {
5806 const CXXRecordDecl *Class = getBaseClassType(Ptr.Designator, PathLength);
5807 if (declaresSameEntity(Class, C))
5808 return CastToDerivedClass(Info, E, Ptr, Class, PathLength);
5809 // We can only walk across public inheritance edges.
5810 if (PathLength > (int)DynType->PathLength &&
5811 !isBaseClassPublic(getBaseClassType(Ptr.Designator, PathLength - 1),
5812 Class))
5813 return RuntimeCheckFailed(nullptr);
5814 }
5815
5816 // Runtime check, phase 2:
5817 // Search the dynamic type for an unambiguous public base of type C.
5818 CXXBasePaths Paths(/*FindAmbiguities=*/true,
5819 /*RecordPaths=*/true, /*DetectVirtual=*/false);
5820 if (DynType->Type->isDerivedFrom(C, Paths) && !Paths.isAmbiguous(CQT) &&
5821 Paths.front().Access == AS_public) {
5822 // Downcast to the dynamic type...
5823 if (!CastToDerivedClass(Info, E, Ptr, DynType->Type, DynType->PathLength))
5824 return false;
5825 // ... then upcast to the chosen base class subobject.
5826 for (CXXBasePathElement &Elem : Paths.front())
5827 if (!HandleLValueBase(Info, E, Ptr, Elem.Class, Elem.Base))
5828 return false;
5829 return true;
5830 }
5831
5832 // Otherwise, the runtime check fails.
5833 return RuntimeCheckFailed(&Paths);
5834 }
5835
5836 namespace {
5837 struct StartLifetimeOfUnionMemberHandler {
5838 EvalInfo &Info;
5839 const Expr *LHSExpr;
5840 const FieldDecl *Field;
5841 bool DuringInit;
5842 bool Failed = false;
5843 static const AccessKinds AccessKind = AK_Assign;
5844
5845 typedef bool result_type;
failed__anon6b379bbb1211::StartLifetimeOfUnionMemberHandler5846 bool failed() { return Failed; }
found__anon6b379bbb1211::StartLifetimeOfUnionMemberHandler5847 bool found(APValue &Subobj, QualType SubobjType) {
5848 // We are supposed to perform no initialization but begin the lifetime of
5849 // the object. We interpret that as meaning to do what default
5850 // initialization of the object would do if all constructors involved were
5851 // trivial:
5852 // * All base, non-variant member, and array element subobjects' lifetimes
5853 // begin
5854 // * No variant members' lifetimes begin
5855 // * All scalar subobjects whose lifetimes begin have indeterminate values
5856 assert(SubobjType->isUnionType());
5857 if (declaresSameEntity(Subobj.getUnionField(), Field)) {
5858 // This union member is already active. If it's also in-lifetime, there's
5859 // nothing to do.
5860 if (Subobj.getUnionValue().hasValue())
5861 return true;
5862 } else if (DuringInit) {
5863 // We're currently in the process of initializing a different union
5864 // member. If we carried on, that initialization would attempt to
5865 // store to an inactive union member, resulting in undefined behavior.
5866 Info.FFDiag(LHSExpr,
5867 diag::note_constexpr_union_member_change_during_init);
5868 return false;
5869 }
5870 APValue Result;
5871 Failed = !getDefaultInitValue(Field->getType(), Result);
5872 Subobj.setUnion(Field, Result);
5873 return true;
5874 }
found__anon6b379bbb1211::StartLifetimeOfUnionMemberHandler5875 bool found(APSInt &Value, QualType SubobjType) {
5876 llvm_unreachable("wrong value kind for union object");
5877 }
found__anon6b379bbb1211::StartLifetimeOfUnionMemberHandler5878 bool found(APFloat &Value, QualType SubobjType) {
5879 llvm_unreachable("wrong value kind for union object");
5880 }
5881 };
5882 } // end anonymous namespace
5883
5884 const AccessKinds StartLifetimeOfUnionMemberHandler::AccessKind;
5885
5886 /// Handle a builtin simple-assignment or a call to a trivial assignment
5887 /// operator whose left-hand side might involve a union member access. If it
5888 /// does, implicitly start the lifetime of any accessed union elements per
5889 /// C++20 [class.union]5.
HandleUnionActiveMemberChange(EvalInfo & Info,const Expr * LHSExpr,const LValue & LHS)5890 static bool HandleUnionActiveMemberChange(EvalInfo &Info, const Expr *LHSExpr,
5891 const LValue &LHS) {
5892 if (LHS.InvalidBase || LHS.Designator.Invalid)
5893 return false;
5894
5895 llvm::SmallVector<std::pair<unsigned, const FieldDecl*>, 4> UnionPathLengths;
5896 // C++ [class.union]p5:
5897 // define the set S(E) of subexpressions of E as follows:
5898 unsigned PathLength = LHS.Designator.Entries.size();
5899 for (const Expr *E = LHSExpr; E != nullptr;) {
5900 // -- If E is of the form A.B, S(E) contains the elements of S(A)...
5901 if (auto *ME = dyn_cast<MemberExpr>(E)) {
5902 auto *FD = dyn_cast<FieldDecl>(ME->getMemberDecl());
5903 // Note that we can't implicitly start the lifetime of a reference,
5904 // so we don't need to proceed any further if we reach one.
5905 if (!FD || FD->getType()->isReferenceType())
5906 break;
5907
5908 // ... and also contains A.B if B names a union member ...
5909 if (FD->getParent()->isUnion()) {
5910 // ... of a non-class, non-array type, or of a class type with a
5911 // trivial default constructor that is not deleted, or an array of
5912 // such types.
5913 auto *RD =
5914 FD->getType()->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
5915 if (!RD || RD->hasTrivialDefaultConstructor())
5916 UnionPathLengths.push_back({PathLength - 1, FD});
5917 }
5918
5919 E = ME->getBase();
5920 --PathLength;
5921 assert(declaresSameEntity(FD,
5922 LHS.Designator.Entries[PathLength]
5923 .getAsBaseOrMember().getPointer()));
5924
5925 // -- If E is of the form A[B] and is interpreted as a built-in array
5926 // subscripting operator, S(E) is [S(the array operand, if any)].
5927 } else if (auto *ASE = dyn_cast<ArraySubscriptExpr>(E)) {
5928 // Step over an ArrayToPointerDecay implicit cast.
5929 auto *Base = ASE->getBase()->IgnoreImplicit();
5930 if (!Base->getType()->isArrayType())
5931 break;
5932
5933 E = Base;
5934 --PathLength;
5935
5936 } else if (auto *ICE = dyn_cast<ImplicitCastExpr>(E)) {
5937 // Step over a derived-to-base conversion.
5938 E = ICE->getSubExpr();
5939 if (ICE->getCastKind() == CK_NoOp)
5940 continue;
5941 if (ICE->getCastKind() != CK_DerivedToBase &&
5942 ICE->getCastKind() != CK_UncheckedDerivedToBase)
5943 break;
5944 // Walk path backwards as we walk up from the base to the derived class.
5945 for (const CXXBaseSpecifier *Elt : llvm::reverse(ICE->path())) {
5946 --PathLength;
5947 (void)Elt;
5948 assert(declaresSameEntity(Elt->getType()->getAsCXXRecordDecl(),
5949 LHS.Designator.Entries[PathLength]
5950 .getAsBaseOrMember().getPointer()));
5951 }
5952
5953 // -- Otherwise, S(E) is empty.
5954 } else {
5955 break;
5956 }
5957 }
5958
5959 // Common case: no unions' lifetimes are started.
5960 if (UnionPathLengths.empty())
5961 return true;
5962
5963 // if modification of X [would access an inactive union member], an object
5964 // of the type of X is implicitly created
5965 CompleteObject Obj =
5966 findCompleteObject(Info, LHSExpr, AK_Assign, LHS, LHSExpr->getType());
5967 if (!Obj)
5968 return false;
5969 for (std::pair<unsigned, const FieldDecl *> LengthAndField :
5970 llvm::reverse(UnionPathLengths)) {
5971 // Form a designator for the union object.
5972 SubobjectDesignator D = LHS.Designator;
5973 D.truncate(Info.Ctx, LHS.Base, LengthAndField.first);
5974
5975 bool DuringInit = Info.isEvaluatingCtorDtor(LHS.Base, D.Entries) ==
5976 ConstructionPhase::AfterBases;
5977 StartLifetimeOfUnionMemberHandler StartLifetime{
5978 Info, LHSExpr, LengthAndField.second, DuringInit};
5979 if (!findSubobject(Info, LHSExpr, Obj, D, StartLifetime))
5980 return false;
5981 }
5982
5983 return true;
5984 }
5985
EvaluateCallArg(const ParmVarDecl * PVD,const Expr * Arg,CallRef Call,EvalInfo & Info,bool NonNull=false)5986 static bool EvaluateCallArg(const ParmVarDecl *PVD, const Expr *Arg,
5987 CallRef Call, EvalInfo &Info,
5988 bool NonNull = false) {
5989 LValue LV;
5990 // Create the parameter slot and register its destruction. For a vararg
5991 // argument, create a temporary.
5992 // FIXME: For calling conventions that destroy parameters in the callee,
5993 // should we consider performing destruction when the function returns
5994 // instead?
5995 APValue &V = PVD ? Info.CurrentCall->createParam(Call, PVD, LV)
5996 : Info.CurrentCall->createTemporary(Arg, Arg->getType(),
5997 ScopeKind::Call, LV);
5998 if (!EvaluateInPlace(V, Info, LV, Arg))
5999 return false;
6000
6001 // Passing a null pointer to an __attribute__((nonnull)) parameter results in
6002 // undefined behavior, so is non-constant.
6003 if (NonNull && V.isLValue() && V.isNullPointer()) {
6004 Info.CCEDiag(Arg, diag::note_non_null_attribute_failed);
6005 return false;
6006 }
6007
6008 return true;
6009 }
6010
6011 /// Evaluate the arguments to a function call.
EvaluateArgs(ArrayRef<const Expr * > Args,CallRef Call,EvalInfo & Info,const FunctionDecl * Callee,bool RightToLeft=false)6012 static bool EvaluateArgs(ArrayRef<const Expr *> Args, CallRef Call,
6013 EvalInfo &Info, const FunctionDecl *Callee,
6014 bool RightToLeft = false) {
6015 bool Success = true;
6016 llvm::SmallBitVector ForbiddenNullArgs;
6017 if (Callee->hasAttr<NonNullAttr>()) {
6018 ForbiddenNullArgs.resize(Args.size());
6019 for (const auto *Attr : Callee->specific_attrs<NonNullAttr>()) {
6020 if (!Attr->args_size()) {
6021 ForbiddenNullArgs.set();
6022 break;
6023 } else
6024 for (auto Idx : Attr->args()) {
6025 unsigned ASTIdx = Idx.getASTIndex();
6026 if (ASTIdx >= Args.size())
6027 continue;
6028 ForbiddenNullArgs[ASTIdx] = 1;
6029 }
6030 }
6031 }
6032 for (unsigned I = 0; I < Args.size(); I++) {
6033 unsigned Idx = RightToLeft ? Args.size() - I - 1 : I;
6034 const ParmVarDecl *PVD =
6035 Idx < Callee->getNumParams() ? Callee->getParamDecl(Idx) : nullptr;
6036 bool NonNull = !ForbiddenNullArgs.empty() && ForbiddenNullArgs[Idx];
6037 if (!EvaluateCallArg(PVD, Args[Idx], Call, Info, NonNull)) {
6038 // If we're checking for a potential constant expression, evaluate all
6039 // initializers even if some of them fail.
6040 if (!Info.noteFailure())
6041 return false;
6042 Success = false;
6043 }
6044 }
6045 return Success;
6046 }
6047
6048 /// Perform a trivial copy from Param, which is the parameter of a copy or move
6049 /// constructor or assignment operator.
handleTrivialCopy(EvalInfo & Info,const ParmVarDecl * Param,const Expr * E,APValue & Result,bool CopyObjectRepresentation)6050 static bool handleTrivialCopy(EvalInfo &Info, const ParmVarDecl *Param,
6051 const Expr *E, APValue &Result,
6052 bool CopyObjectRepresentation) {
6053 // Find the reference argument.
6054 CallStackFrame *Frame = Info.CurrentCall;
6055 APValue *RefValue = Info.getParamSlot(Frame->Arguments, Param);
6056 if (!RefValue) {
6057 Info.FFDiag(E);
6058 return false;
6059 }
6060
6061 // Copy out the contents of the RHS object.
6062 LValue RefLValue;
6063 RefLValue.setFrom(Info.Ctx, *RefValue);
6064 return handleLValueToRValueConversion(
6065 Info, E, Param->getType().getNonReferenceType(), RefLValue, Result,
6066 CopyObjectRepresentation);
6067 }
6068
6069 /// 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)6070 static bool HandleFunctionCall(SourceLocation CallLoc,
6071 const FunctionDecl *Callee, const LValue *This,
6072 ArrayRef<const Expr *> Args, CallRef Call,
6073 const Stmt *Body, EvalInfo &Info,
6074 APValue &Result, const LValue *ResultSlot) {
6075 if (!Info.CheckCallLimit(CallLoc))
6076 return false;
6077
6078 CallStackFrame Frame(Info, CallLoc, Callee, This, Call);
6079
6080 // For a trivial copy or move assignment, perform an APValue copy. This is
6081 // essential for unions, where the operations performed by the assignment
6082 // operator cannot be represented as statements.
6083 //
6084 // Skip this for non-union classes with no fields; in that case, the defaulted
6085 // copy/move does not actually read the object.
6086 const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(Callee);
6087 if (MD && MD->isDefaulted() &&
6088 (MD->getParent()->isUnion() ||
6089 (MD->isTrivial() &&
6090 isReadByLvalueToRvalueConversion(MD->getParent())))) {
6091 assert(This &&
6092 (MD->isCopyAssignmentOperator() || MD->isMoveAssignmentOperator()));
6093 APValue RHSValue;
6094 if (!handleTrivialCopy(Info, MD->getParamDecl(0), Args[0], RHSValue,
6095 MD->getParent()->isUnion()))
6096 return false;
6097 if (Info.getLangOpts().CPlusPlus20 && MD->isTrivial() &&
6098 !HandleUnionActiveMemberChange(Info, Args[0], *This))
6099 return false;
6100 if (!handleAssignment(Info, Args[0], *This, MD->getThisType(),
6101 RHSValue))
6102 return false;
6103 This->moveInto(Result);
6104 return true;
6105 } else if (MD && isLambdaCallOperator(MD)) {
6106 // We're in a lambda; determine the lambda capture field maps unless we're
6107 // just constexpr checking a lambda's call operator. constexpr checking is
6108 // done before the captures have been added to the closure object (unless
6109 // we're inferring constexpr-ness), so we don't have access to them in this
6110 // case. But since we don't need the captures to constexpr check, we can
6111 // just ignore them.
6112 if (!Info.checkingPotentialConstantExpression())
6113 MD->getParent()->getCaptureFields(Frame.LambdaCaptureFields,
6114 Frame.LambdaThisCaptureField);
6115 }
6116
6117 StmtResult Ret = {Result, ResultSlot};
6118 EvalStmtResult ESR = EvaluateStmt(Ret, Info, Body);
6119 if (ESR == ESR_Succeeded) {
6120 if (Callee->getReturnType()->isVoidType())
6121 return true;
6122 Info.FFDiag(Callee->getEndLoc(), diag::note_constexpr_no_return);
6123 }
6124 return ESR == ESR_Returned;
6125 }
6126
6127 /// Evaluate a constructor call.
HandleConstructorCall(const Expr * E,const LValue & This,CallRef Call,const CXXConstructorDecl * Definition,EvalInfo & Info,APValue & Result)6128 static bool HandleConstructorCall(const Expr *E, const LValue &This,
6129 CallRef Call,
6130 const CXXConstructorDecl *Definition,
6131 EvalInfo &Info, APValue &Result) {
6132 SourceLocation CallLoc = E->getExprLoc();
6133 if (!Info.CheckCallLimit(CallLoc))
6134 return false;
6135
6136 const CXXRecordDecl *RD = Definition->getParent();
6137 if (RD->getNumVBases()) {
6138 Info.FFDiag(CallLoc, diag::note_constexpr_virtual_base) << RD;
6139 return false;
6140 }
6141
6142 EvalInfo::EvaluatingConstructorRAII EvalObj(
6143 Info,
6144 ObjectUnderConstruction{This.getLValueBase(), This.Designator.Entries},
6145 RD->getNumBases());
6146 CallStackFrame Frame(Info, CallLoc, Definition, &This, Call);
6147
6148 // FIXME: Creating an APValue just to hold a nonexistent return value is
6149 // wasteful.
6150 APValue RetVal;
6151 StmtResult Ret = {RetVal, nullptr};
6152
6153 // If it's a delegating constructor, delegate.
6154 if (Definition->isDelegatingConstructor()) {
6155 CXXConstructorDecl::init_const_iterator I = Definition->init_begin();
6156 if ((*I)->getInit()->isValueDependent()) {
6157 if (!EvaluateDependentExpr((*I)->getInit(), Info))
6158 return false;
6159 } else {
6160 FullExpressionRAII InitScope(Info);
6161 if (!EvaluateInPlace(Result, Info, This, (*I)->getInit()) ||
6162 !InitScope.destroy())
6163 return false;
6164 }
6165 return EvaluateStmt(Ret, Info, Definition->getBody()) != ESR_Failed;
6166 }
6167
6168 // For a trivial copy or move constructor, perform an APValue copy. This is
6169 // essential for unions (or classes with anonymous union members), where the
6170 // operations performed by the constructor cannot be represented by
6171 // ctor-initializers.
6172 //
6173 // Skip this for empty non-union classes; we should not perform an
6174 // lvalue-to-rvalue conversion on them because their copy constructor does not
6175 // actually read them.
6176 if (Definition->isDefaulted() && Definition->isCopyOrMoveConstructor() &&
6177 (Definition->getParent()->isUnion() ||
6178 (Definition->isTrivial() &&
6179 isReadByLvalueToRvalueConversion(Definition->getParent())))) {
6180 return handleTrivialCopy(Info, Definition->getParamDecl(0), E, Result,
6181 Definition->getParent()->isUnion());
6182 }
6183
6184 // Reserve space for the struct members.
6185 if (!Result.hasValue()) {
6186 if (!RD->isUnion())
6187 Result = APValue(APValue::UninitStruct(), RD->getNumBases(),
6188 std::distance(RD->field_begin(), RD->field_end()));
6189 else
6190 // A union starts with no active member.
6191 Result = APValue((const FieldDecl*)nullptr);
6192 }
6193
6194 if (RD->isInvalidDecl()) return false;
6195 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
6196
6197 // A scope for temporaries lifetime-extended by reference members.
6198 BlockScopeRAII LifetimeExtendedScope(Info);
6199
6200 bool Success = true;
6201 unsigned BasesSeen = 0;
6202 #ifndef NDEBUG
6203 CXXRecordDecl::base_class_const_iterator BaseIt = RD->bases_begin();
6204 #endif
6205 CXXRecordDecl::field_iterator FieldIt = RD->field_begin();
6206 auto SkipToField = [&](FieldDecl *FD, bool Indirect) {
6207 // We might be initializing the same field again if this is an indirect
6208 // field initialization.
6209 if (FieldIt == RD->field_end() ||
6210 FieldIt->getFieldIndex() > FD->getFieldIndex()) {
6211 assert(Indirect && "fields out of order?");
6212 return;
6213 }
6214
6215 // Default-initialize any fields with no explicit initializer.
6216 for (; !declaresSameEntity(*FieldIt, FD); ++FieldIt) {
6217 assert(FieldIt != RD->field_end() && "missing field?");
6218 if (!FieldIt->isUnnamedBitfield())
6219 Success &= getDefaultInitValue(
6220 FieldIt->getType(),
6221 Result.getStructField(FieldIt->getFieldIndex()));
6222 }
6223 ++FieldIt;
6224 };
6225 for (const auto *I : Definition->inits()) {
6226 LValue Subobject = This;
6227 LValue SubobjectParent = This;
6228 APValue *Value = &Result;
6229
6230 // Determine the subobject to initialize.
6231 FieldDecl *FD = nullptr;
6232 if (I->isBaseInitializer()) {
6233 QualType BaseType(I->getBaseClass(), 0);
6234 #ifndef NDEBUG
6235 // Non-virtual base classes are initialized in the order in the class
6236 // definition. We have already checked for virtual base classes.
6237 assert(!BaseIt->isVirtual() && "virtual base for literal type");
6238 assert(Info.Ctx.hasSameType(BaseIt->getType(), BaseType) &&
6239 "base class initializers not in expected order");
6240 ++BaseIt;
6241 #endif
6242 if (!HandleLValueDirectBase(Info, I->getInit(), Subobject, RD,
6243 BaseType->getAsCXXRecordDecl(), &Layout))
6244 return false;
6245 Value = &Result.getStructBase(BasesSeen++);
6246 } else if ((FD = I->getMember())) {
6247 if (!HandleLValueMember(Info, I->getInit(), Subobject, FD, &Layout))
6248 return false;
6249 if (RD->isUnion()) {
6250 Result = APValue(FD);
6251 Value = &Result.getUnionValue();
6252 } else {
6253 SkipToField(FD, false);
6254 Value = &Result.getStructField(FD->getFieldIndex());
6255 }
6256 } else if (IndirectFieldDecl *IFD = I->getIndirectMember()) {
6257 // Walk the indirect field decl's chain to find the object to initialize,
6258 // and make sure we've initialized every step along it.
6259 auto IndirectFieldChain = IFD->chain();
6260 for (auto *C : IndirectFieldChain) {
6261 FD = cast<FieldDecl>(C);
6262 CXXRecordDecl *CD = cast<CXXRecordDecl>(FD->getParent());
6263 // Switch the union field if it differs. This happens if we had
6264 // preceding zero-initialization, and we're now initializing a union
6265 // subobject other than the first.
6266 // FIXME: In this case, the values of the other subobjects are
6267 // specified, since zero-initialization sets all padding bits to zero.
6268 if (!Value->hasValue() ||
6269 (Value->isUnion() && Value->getUnionField() != FD)) {
6270 if (CD->isUnion())
6271 *Value = APValue(FD);
6272 else
6273 // FIXME: This immediately starts the lifetime of all members of
6274 // an anonymous struct. It would be preferable to strictly start
6275 // member lifetime in initialization order.
6276 Success &= getDefaultInitValue(Info.Ctx.getRecordType(CD), *Value);
6277 }
6278 // Store Subobject as its parent before updating it for the last element
6279 // in the chain.
6280 if (C == IndirectFieldChain.back())
6281 SubobjectParent = Subobject;
6282 if (!HandleLValueMember(Info, I->getInit(), Subobject, FD))
6283 return false;
6284 if (CD->isUnion())
6285 Value = &Value->getUnionValue();
6286 else {
6287 if (C == IndirectFieldChain.front() && !RD->isUnion())
6288 SkipToField(FD, true);
6289 Value = &Value->getStructField(FD->getFieldIndex());
6290 }
6291 }
6292 } else {
6293 llvm_unreachable("unknown base initializer kind");
6294 }
6295
6296 // Need to override This for implicit field initializers as in this case
6297 // This refers to innermost anonymous struct/union containing initializer,
6298 // not to currently constructed class.
6299 const Expr *Init = I->getInit();
6300 if (Init->isValueDependent()) {
6301 if (!EvaluateDependentExpr(Init, Info))
6302 return false;
6303 } else {
6304 ThisOverrideRAII ThisOverride(*Info.CurrentCall, &SubobjectParent,
6305 isa<CXXDefaultInitExpr>(Init));
6306 FullExpressionRAII InitScope(Info);
6307 if (!EvaluateInPlace(*Value, Info, Subobject, Init) ||
6308 (FD && FD->isBitField() &&
6309 !truncateBitfieldValue(Info, Init, *Value, FD))) {
6310 // If we're checking for a potential constant expression, evaluate all
6311 // initializers even if some of them fail.
6312 if (!Info.noteFailure())
6313 return false;
6314 Success = false;
6315 }
6316 }
6317
6318 // This is the point at which the dynamic type of the object becomes this
6319 // class type.
6320 if (I->isBaseInitializer() && BasesSeen == RD->getNumBases())
6321 EvalObj.finishedConstructingBases();
6322 }
6323
6324 // Default-initialize any remaining fields.
6325 if (!RD->isUnion()) {
6326 for (; FieldIt != RD->field_end(); ++FieldIt) {
6327 if (!FieldIt->isUnnamedBitfield())
6328 Success &= getDefaultInitValue(
6329 FieldIt->getType(),
6330 Result.getStructField(FieldIt->getFieldIndex()));
6331 }
6332 }
6333
6334 EvalObj.finishedConstructingFields();
6335
6336 return Success &&
6337 EvaluateStmt(Ret, Info, Definition->getBody()) != ESR_Failed &&
6338 LifetimeExtendedScope.destroy();
6339 }
6340
HandleConstructorCall(const Expr * E,const LValue & This,ArrayRef<const Expr * > Args,const CXXConstructorDecl * Definition,EvalInfo & Info,APValue & Result)6341 static bool HandleConstructorCall(const Expr *E, const LValue &This,
6342 ArrayRef<const Expr*> Args,
6343 const CXXConstructorDecl *Definition,
6344 EvalInfo &Info, APValue &Result) {
6345 CallScopeRAII CallScope(Info);
6346 CallRef Call = Info.CurrentCall->createCall(Definition);
6347 if (!EvaluateArgs(Args, Call, Info, Definition))
6348 return false;
6349
6350 return HandleConstructorCall(E, This, Call, Definition, Info, Result) &&
6351 CallScope.destroy();
6352 }
6353
HandleDestructionImpl(EvalInfo & Info,SourceLocation CallLoc,const LValue & This,APValue & Value,QualType T)6354 static bool HandleDestructionImpl(EvalInfo &Info, SourceLocation CallLoc,
6355 const LValue &This, APValue &Value,
6356 QualType T) {
6357 // Objects can only be destroyed while they're within their lifetimes.
6358 // FIXME: We have no representation for whether an object of type nullptr_t
6359 // is in its lifetime; it usually doesn't matter. Perhaps we should model it
6360 // as indeterminate instead?
6361 if (Value.isAbsent() && !T->isNullPtrType()) {
6362 APValue Printable;
6363 This.moveInto(Printable);
6364 Info.FFDiag(CallLoc, diag::note_constexpr_destroy_out_of_lifetime)
6365 << Printable.getAsString(Info.Ctx, Info.Ctx.getLValueReferenceType(T));
6366 return false;
6367 }
6368
6369 // Invent an expression for location purposes.
6370 // FIXME: We shouldn't need to do this.
6371 OpaqueValueExpr LocE(CallLoc, Info.Ctx.IntTy, VK_RValue);
6372
6373 // For arrays, destroy elements right-to-left.
6374 if (const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(T)) {
6375 uint64_t Size = CAT->getSize().getZExtValue();
6376 QualType ElemT = CAT->getElementType();
6377
6378 LValue ElemLV = This;
6379 ElemLV.addArray(Info, &LocE, CAT);
6380 if (!HandleLValueArrayAdjustment(Info, &LocE, ElemLV, ElemT, Size))
6381 return false;
6382
6383 // Ensure that we have actual array elements available to destroy; the
6384 // destructors might mutate the value, so we can't run them on the array
6385 // filler.
6386 if (Size && Size > Value.getArrayInitializedElts())
6387 expandArray(Value, Value.getArraySize() - 1);
6388
6389 for (; Size != 0; --Size) {
6390 APValue &Elem = Value.getArrayInitializedElt(Size - 1);
6391 if (!HandleLValueArrayAdjustment(Info, &LocE, ElemLV, ElemT, -1) ||
6392 !HandleDestructionImpl(Info, CallLoc, ElemLV, Elem, ElemT))
6393 return false;
6394 }
6395
6396 // End the lifetime of this array now.
6397 Value = APValue();
6398 return true;
6399 }
6400
6401 const CXXRecordDecl *RD = T->getAsCXXRecordDecl();
6402 if (!RD) {
6403 if (T.isDestructedType()) {
6404 Info.FFDiag(CallLoc, diag::note_constexpr_unsupported_destruction) << T;
6405 return false;
6406 }
6407
6408 Value = APValue();
6409 return true;
6410 }
6411
6412 if (RD->getNumVBases()) {
6413 Info.FFDiag(CallLoc, diag::note_constexpr_virtual_base) << RD;
6414 return false;
6415 }
6416
6417 const CXXDestructorDecl *DD = RD->getDestructor();
6418 if (!DD && !RD->hasTrivialDestructor()) {
6419 Info.FFDiag(CallLoc);
6420 return false;
6421 }
6422
6423 if (!DD || DD->isTrivial() ||
6424 (RD->isAnonymousStructOrUnion() && RD->isUnion())) {
6425 // A trivial destructor just ends the lifetime of the object. Check for
6426 // this case before checking for a body, because we might not bother
6427 // building a body for a trivial destructor. Note that it doesn't matter
6428 // whether the destructor is constexpr in this case; all trivial
6429 // destructors are constexpr.
6430 //
6431 // If an anonymous union would be destroyed, some enclosing destructor must
6432 // have been explicitly defined, and the anonymous union destruction should
6433 // have no effect.
6434 Value = APValue();
6435 return true;
6436 }
6437
6438 if (!Info.CheckCallLimit(CallLoc))
6439 return false;
6440
6441 const FunctionDecl *Definition = nullptr;
6442 const Stmt *Body = DD->getBody(Definition);
6443
6444 if (!CheckConstexprFunction(Info, CallLoc, DD, Definition, Body))
6445 return false;
6446
6447 CallStackFrame Frame(Info, CallLoc, Definition, &This, CallRef());
6448
6449 // We're now in the period of destruction of this object.
6450 unsigned BasesLeft = RD->getNumBases();
6451 EvalInfo::EvaluatingDestructorRAII EvalObj(
6452 Info,
6453 ObjectUnderConstruction{This.getLValueBase(), This.Designator.Entries});
6454 if (!EvalObj.DidInsert) {
6455 // C++2a [class.dtor]p19:
6456 // the behavior is undefined if the destructor is invoked for an object
6457 // whose lifetime has ended
6458 // (Note that formally the lifetime ends when the period of destruction
6459 // begins, even though certain uses of the object remain valid until the
6460 // period of destruction ends.)
6461 Info.FFDiag(CallLoc, diag::note_constexpr_double_destroy);
6462 return false;
6463 }
6464
6465 // FIXME: Creating an APValue just to hold a nonexistent return value is
6466 // wasteful.
6467 APValue RetVal;
6468 StmtResult Ret = {RetVal, nullptr};
6469 if (EvaluateStmt(Ret, Info, Definition->getBody()) == ESR_Failed)
6470 return false;
6471
6472 // A union destructor does not implicitly destroy its members.
6473 if (RD->isUnion())
6474 return true;
6475
6476 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
6477
6478 // We don't have a good way to iterate fields in reverse, so collect all the
6479 // fields first and then walk them backwards.
6480 SmallVector<FieldDecl*, 16> Fields(RD->field_begin(), RD->field_end());
6481 for (const FieldDecl *FD : llvm::reverse(Fields)) {
6482 if (FD->isUnnamedBitfield())
6483 continue;
6484
6485 LValue Subobject = This;
6486 if (!HandleLValueMember(Info, &LocE, Subobject, FD, &Layout))
6487 return false;
6488
6489 APValue *SubobjectValue = &Value.getStructField(FD->getFieldIndex());
6490 if (!HandleDestructionImpl(Info, CallLoc, Subobject, *SubobjectValue,
6491 FD->getType()))
6492 return false;
6493 }
6494
6495 if (BasesLeft != 0)
6496 EvalObj.startedDestroyingBases();
6497
6498 // Destroy base classes in reverse order.
6499 for (const CXXBaseSpecifier &Base : llvm::reverse(RD->bases())) {
6500 --BasesLeft;
6501
6502 QualType BaseType = Base.getType();
6503 LValue Subobject = This;
6504 if (!HandleLValueDirectBase(Info, &LocE, Subobject, RD,
6505 BaseType->getAsCXXRecordDecl(), &Layout))
6506 return false;
6507
6508 APValue *SubobjectValue = &Value.getStructBase(BasesLeft);
6509 if (!HandleDestructionImpl(Info, CallLoc, Subobject, *SubobjectValue,
6510 BaseType))
6511 return false;
6512 }
6513 assert(BasesLeft == 0 && "NumBases was wrong?");
6514
6515 // The period of destruction ends now. The object is gone.
6516 Value = APValue();
6517 return true;
6518 }
6519
6520 namespace {
6521 struct DestroyObjectHandler {
6522 EvalInfo &Info;
6523 const Expr *E;
6524 const LValue &This;
6525 const AccessKinds AccessKind;
6526
6527 typedef bool result_type;
failed__anon6b379bbb1411::DestroyObjectHandler6528 bool failed() { return false; }
found__anon6b379bbb1411::DestroyObjectHandler6529 bool found(APValue &Subobj, QualType SubobjType) {
6530 return HandleDestructionImpl(Info, E->getExprLoc(), This, Subobj,
6531 SubobjType);
6532 }
found__anon6b379bbb1411::DestroyObjectHandler6533 bool found(APSInt &Value, QualType SubobjType) {
6534 Info.FFDiag(E, diag::note_constexpr_destroy_complex_elem);
6535 return false;
6536 }
found__anon6b379bbb1411::DestroyObjectHandler6537 bool found(APFloat &Value, QualType SubobjType) {
6538 Info.FFDiag(E, diag::note_constexpr_destroy_complex_elem);
6539 return false;
6540 }
6541 };
6542 }
6543
6544 /// Perform a destructor or pseudo-destructor call on the given object, which
6545 /// might in general not be a complete object.
HandleDestruction(EvalInfo & Info,const Expr * E,const LValue & This,QualType ThisType)6546 static bool HandleDestruction(EvalInfo &Info, const Expr *E,
6547 const LValue &This, QualType ThisType) {
6548 CompleteObject Obj = findCompleteObject(Info, E, AK_Destroy, This, ThisType);
6549 DestroyObjectHandler Handler = {Info, E, This, AK_Destroy};
6550 return Obj && findSubobject(Info, E, Obj, This.Designator, Handler);
6551 }
6552
6553 /// Destroy and end the lifetime of the given complete object.
HandleDestruction(EvalInfo & Info,SourceLocation Loc,APValue::LValueBase LVBase,APValue & Value,QualType T)6554 static bool HandleDestruction(EvalInfo &Info, SourceLocation Loc,
6555 APValue::LValueBase LVBase, APValue &Value,
6556 QualType T) {
6557 // If we've had an unmodeled side-effect, we can't rely on mutable state
6558 // (such as the object we're about to destroy) being correct.
6559 if (Info.EvalStatus.HasSideEffects)
6560 return false;
6561
6562 LValue LV;
6563 LV.set({LVBase});
6564 return HandleDestructionImpl(Info, Loc, LV, Value, T);
6565 }
6566
6567 /// Perform a call to 'perator new' or to `__builtin_operator_new'.
HandleOperatorNewCall(EvalInfo & Info,const CallExpr * E,LValue & Result)6568 static bool HandleOperatorNewCall(EvalInfo &Info, const CallExpr *E,
6569 LValue &Result) {
6570 if (Info.checkingPotentialConstantExpression() ||
6571 Info.SpeculativeEvaluationDepth)
6572 return false;
6573
6574 // This is permitted only within a call to std::allocator<T>::allocate.
6575 auto Caller = Info.getStdAllocatorCaller("allocate");
6576 if (!Caller) {
6577 Info.FFDiag(E->getExprLoc(), Info.getLangOpts().CPlusPlus20
6578 ? diag::note_constexpr_new_untyped
6579 : diag::note_constexpr_new);
6580 return false;
6581 }
6582
6583 QualType ElemType = Caller.ElemType;
6584 if (ElemType->isIncompleteType() || ElemType->isFunctionType()) {
6585 Info.FFDiag(E->getExprLoc(),
6586 diag::note_constexpr_new_not_complete_object_type)
6587 << (ElemType->isIncompleteType() ? 0 : 1) << ElemType;
6588 return false;
6589 }
6590
6591 APSInt ByteSize;
6592 if (!EvaluateInteger(E->getArg(0), ByteSize, Info))
6593 return false;
6594 bool IsNothrow = false;
6595 for (unsigned I = 1, N = E->getNumArgs(); I != N; ++I) {
6596 EvaluateIgnoredValue(Info, E->getArg(I));
6597 IsNothrow |= E->getType()->isNothrowT();
6598 }
6599
6600 CharUnits ElemSize;
6601 if (!HandleSizeof(Info, E->getExprLoc(), ElemType, ElemSize))
6602 return false;
6603 APInt Size, Remainder;
6604 APInt ElemSizeAP(ByteSize.getBitWidth(), ElemSize.getQuantity());
6605 APInt::udivrem(ByteSize, ElemSizeAP, Size, Remainder);
6606 if (Remainder != 0) {
6607 // This likely indicates a bug in the implementation of 'std::allocator'.
6608 Info.FFDiag(E->getExprLoc(), diag::note_constexpr_operator_new_bad_size)
6609 << ByteSize << APSInt(ElemSizeAP, true) << ElemType;
6610 return false;
6611 }
6612
6613 if (ByteSize.getActiveBits() > ConstantArrayType::getMaxSizeBits(Info.Ctx)) {
6614 if (IsNothrow) {
6615 Result.setNull(Info.Ctx, E->getType());
6616 return true;
6617 }
6618
6619 Info.FFDiag(E, diag::note_constexpr_new_too_large) << APSInt(Size, true);
6620 return false;
6621 }
6622
6623 QualType AllocType = Info.Ctx.getConstantArrayType(ElemType, Size, nullptr,
6624 ArrayType::Normal, 0);
6625 APValue *Val = Info.createHeapAlloc(E, AllocType, Result);
6626 *Val = APValue(APValue::UninitArray(), 0, Size.getZExtValue());
6627 Result.addArray(Info, E, cast<ConstantArrayType>(AllocType));
6628 return true;
6629 }
6630
hasVirtualDestructor(QualType T)6631 static bool hasVirtualDestructor(QualType T) {
6632 if (CXXRecordDecl *RD = T->getAsCXXRecordDecl())
6633 if (CXXDestructorDecl *DD = RD->getDestructor())
6634 return DD->isVirtual();
6635 return false;
6636 }
6637
getVirtualOperatorDelete(QualType T)6638 static const FunctionDecl *getVirtualOperatorDelete(QualType T) {
6639 if (CXXRecordDecl *RD = T->getAsCXXRecordDecl())
6640 if (CXXDestructorDecl *DD = RD->getDestructor())
6641 return DD->isVirtual() ? DD->getOperatorDelete() : nullptr;
6642 return nullptr;
6643 }
6644
6645 /// Check that the given object is a suitable pointer to a heap allocation that
6646 /// still exists and is of the right kind for the purpose of a deletion.
6647 ///
6648 /// On success, returns the heap allocation to deallocate. On failure, produces
6649 /// a diagnostic and returns None.
CheckDeleteKind(EvalInfo & Info,const Expr * E,const LValue & Pointer,DynAlloc::Kind DeallocKind)6650 static Optional<DynAlloc *> CheckDeleteKind(EvalInfo &Info, const Expr *E,
6651 const LValue &Pointer,
6652 DynAlloc::Kind DeallocKind) {
6653 auto PointerAsString = [&] {
6654 return Pointer.toString(Info.Ctx, Info.Ctx.VoidPtrTy);
6655 };
6656
6657 DynamicAllocLValue DA = Pointer.Base.dyn_cast<DynamicAllocLValue>();
6658 if (!DA) {
6659 Info.FFDiag(E, diag::note_constexpr_delete_not_heap_alloc)
6660 << PointerAsString();
6661 if (Pointer.Base)
6662 NoteLValueLocation(Info, Pointer.Base);
6663 return None;
6664 }
6665
6666 Optional<DynAlloc *> Alloc = Info.lookupDynamicAlloc(DA);
6667 if (!Alloc) {
6668 Info.FFDiag(E, diag::note_constexpr_double_delete);
6669 return None;
6670 }
6671
6672 QualType AllocType = Pointer.Base.getDynamicAllocType();
6673 if (DeallocKind != (*Alloc)->getKind()) {
6674 Info.FFDiag(E, diag::note_constexpr_new_delete_mismatch)
6675 << DeallocKind << (*Alloc)->getKind() << AllocType;
6676 NoteLValueLocation(Info, Pointer.Base);
6677 return None;
6678 }
6679
6680 bool Subobject = false;
6681 if (DeallocKind == DynAlloc::New) {
6682 Subobject = Pointer.Designator.MostDerivedPathLength != 0 ||
6683 Pointer.Designator.isOnePastTheEnd();
6684 } else {
6685 Subobject = Pointer.Designator.Entries.size() != 1 ||
6686 Pointer.Designator.Entries[0].getAsArrayIndex() != 0;
6687 }
6688 if (Subobject) {
6689 Info.FFDiag(E, diag::note_constexpr_delete_subobject)
6690 << PointerAsString() << Pointer.Designator.isOnePastTheEnd();
6691 return None;
6692 }
6693
6694 return Alloc;
6695 }
6696
6697 // Perform a call to 'operator delete' or '__builtin_operator_delete'.
HandleOperatorDeleteCall(EvalInfo & Info,const CallExpr * E)6698 bool HandleOperatorDeleteCall(EvalInfo &Info, const CallExpr *E) {
6699 if (Info.checkingPotentialConstantExpression() ||
6700 Info.SpeculativeEvaluationDepth)
6701 return false;
6702
6703 // This is permitted only within a call to std::allocator<T>::deallocate.
6704 if (!Info.getStdAllocatorCaller("deallocate")) {
6705 Info.FFDiag(E->getExprLoc());
6706 return true;
6707 }
6708
6709 LValue Pointer;
6710 if (!EvaluatePointer(E->getArg(0), Pointer, Info))
6711 return false;
6712 for (unsigned I = 1, N = E->getNumArgs(); I != N; ++I)
6713 EvaluateIgnoredValue(Info, E->getArg(I));
6714
6715 if (Pointer.Designator.Invalid)
6716 return false;
6717
6718 // Deleting a null pointer would have no effect, but it's not permitted by
6719 // std::allocator<T>::deallocate's contract.
6720 if (Pointer.isNullPointer()) {
6721 Info.CCEDiag(E->getExprLoc(), diag::note_constexpr_deallocate_null);
6722 return true;
6723 }
6724
6725 if (!CheckDeleteKind(Info, E, Pointer, DynAlloc::StdAllocator))
6726 return false;
6727
6728 Info.HeapAllocs.erase(Pointer.Base.get<DynamicAllocLValue>());
6729 return true;
6730 }
6731
6732 //===----------------------------------------------------------------------===//
6733 // Generic Evaluation
6734 //===----------------------------------------------------------------------===//
6735 namespace {
6736
6737 class BitCastBuffer {
6738 // FIXME: We're going to need bit-level granularity when we support
6739 // bit-fields.
6740 // FIXME: Its possible under the C++ standard for 'char' to not be 8 bits, but
6741 // we don't support a host or target where that is the case. Still, we should
6742 // use a more generic type in case we ever do.
6743 SmallVector<Optional<unsigned char>, 32> Bytes;
6744
6745 static_assert(std::numeric_limits<unsigned char>::digits >= 8,
6746 "Need at least 8 bit unsigned char");
6747
6748 bool TargetIsLittleEndian;
6749
6750 public:
BitCastBuffer(CharUnits Width,bool TargetIsLittleEndian)6751 BitCastBuffer(CharUnits Width, bool TargetIsLittleEndian)
6752 : Bytes(Width.getQuantity()),
6753 TargetIsLittleEndian(TargetIsLittleEndian) {}
6754
6755 LLVM_NODISCARD
readObject(CharUnits Offset,CharUnits Width,SmallVectorImpl<unsigned char> & Output) const6756 bool readObject(CharUnits Offset, CharUnits Width,
6757 SmallVectorImpl<unsigned char> &Output) const {
6758 for (CharUnits I = Offset, E = Offset + Width; I != E; ++I) {
6759 // If a byte of an integer is uninitialized, then the whole integer is
6760 // uninitalized.
6761 if (!Bytes[I.getQuantity()])
6762 return false;
6763 Output.push_back(*Bytes[I.getQuantity()]);
6764 }
6765 if (llvm::sys::IsLittleEndianHost != TargetIsLittleEndian)
6766 std::reverse(Output.begin(), Output.end());
6767 return true;
6768 }
6769
writeObject(CharUnits Offset,SmallVectorImpl<unsigned char> & Input)6770 void writeObject(CharUnits Offset, SmallVectorImpl<unsigned char> &Input) {
6771 if (llvm::sys::IsLittleEndianHost != TargetIsLittleEndian)
6772 std::reverse(Input.begin(), Input.end());
6773
6774 size_t Index = 0;
6775 for (unsigned char Byte : Input) {
6776 assert(!Bytes[Offset.getQuantity() + Index] && "overwriting a byte?");
6777 Bytes[Offset.getQuantity() + Index] = Byte;
6778 ++Index;
6779 }
6780 }
6781
size()6782 size_t size() { return Bytes.size(); }
6783 };
6784
6785 /// Traverse an APValue to produce an BitCastBuffer, emulating how the current
6786 /// target would represent the value at runtime.
6787 class APValueToBufferConverter {
6788 EvalInfo &Info;
6789 BitCastBuffer Buffer;
6790 const CastExpr *BCE;
6791
APValueToBufferConverter(EvalInfo & Info,CharUnits ObjectWidth,const CastExpr * BCE)6792 APValueToBufferConverter(EvalInfo &Info, CharUnits ObjectWidth,
6793 const CastExpr *BCE)
6794 : Info(Info),
6795 Buffer(ObjectWidth, Info.Ctx.getTargetInfo().isLittleEndian()),
6796 BCE(BCE) {}
6797
visit(const APValue & Val,QualType Ty)6798 bool visit(const APValue &Val, QualType Ty) {
6799 return visit(Val, Ty, CharUnits::fromQuantity(0));
6800 }
6801
6802 // Write out Val with type Ty into Buffer starting at Offset.
visit(const APValue & Val,QualType Ty,CharUnits Offset)6803 bool visit(const APValue &Val, QualType Ty, CharUnits Offset) {
6804 assert((size_t)Offset.getQuantity() <= Buffer.size());
6805
6806 // As a special case, nullptr_t has an indeterminate value.
6807 if (Ty->isNullPtrType())
6808 return true;
6809
6810 // Dig through Src to find the byte at SrcOffset.
6811 switch (Val.getKind()) {
6812 case APValue::Indeterminate:
6813 case APValue::None:
6814 return true;
6815
6816 case APValue::Int:
6817 return visitInt(Val.getInt(), Ty, Offset);
6818 case APValue::Float:
6819 return visitFloat(Val.getFloat(), Ty, Offset);
6820 case APValue::Array:
6821 return visitArray(Val, Ty, Offset);
6822 case APValue::Struct:
6823 return visitRecord(Val, Ty, Offset);
6824
6825 case APValue::ComplexInt:
6826 case APValue::ComplexFloat:
6827 case APValue::Vector:
6828 case APValue::FixedPoint:
6829 // FIXME: We should support these.
6830
6831 case APValue::Union:
6832 case APValue::MemberPointer:
6833 case APValue::AddrLabelDiff: {
6834 Info.FFDiag(BCE->getBeginLoc(),
6835 diag::note_constexpr_bit_cast_unsupported_type)
6836 << Ty;
6837 return false;
6838 }
6839
6840 case APValue::LValue:
6841 llvm_unreachable("LValue subobject in bit_cast?");
6842 }
6843 llvm_unreachable("Unhandled APValue::ValueKind");
6844 }
6845
visitRecord(const APValue & Val,QualType Ty,CharUnits Offset)6846 bool visitRecord(const APValue &Val, QualType Ty, CharUnits Offset) {
6847 const RecordDecl *RD = Ty->getAsRecordDecl();
6848 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
6849
6850 // Visit the base classes.
6851 if (auto *CXXRD = dyn_cast<CXXRecordDecl>(RD)) {
6852 for (size_t I = 0, E = CXXRD->getNumBases(); I != E; ++I) {
6853 const CXXBaseSpecifier &BS = CXXRD->bases_begin()[I];
6854 CXXRecordDecl *BaseDecl = BS.getType()->getAsCXXRecordDecl();
6855
6856 if (!visitRecord(Val.getStructBase(I), BS.getType(),
6857 Layout.getBaseClassOffset(BaseDecl) + Offset))
6858 return false;
6859 }
6860 }
6861
6862 // Visit the fields.
6863 unsigned FieldIdx = 0;
6864 for (FieldDecl *FD : RD->fields()) {
6865 if (FD->isBitField()) {
6866 Info.FFDiag(BCE->getBeginLoc(),
6867 diag::note_constexpr_bit_cast_unsupported_bitfield);
6868 return false;
6869 }
6870
6871 uint64_t FieldOffsetBits = Layout.getFieldOffset(FieldIdx);
6872
6873 assert(FieldOffsetBits % Info.Ctx.getCharWidth() == 0 &&
6874 "only bit-fields can have sub-char alignment");
6875 CharUnits FieldOffset =
6876 Info.Ctx.toCharUnitsFromBits(FieldOffsetBits) + Offset;
6877 QualType FieldTy = FD->getType();
6878 if (!visit(Val.getStructField(FieldIdx), FieldTy, FieldOffset))
6879 return false;
6880 ++FieldIdx;
6881 }
6882
6883 return true;
6884 }
6885
visitArray(const APValue & Val,QualType Ty,CharUnits Offset)6886 bool visitArray(const APValue &Val, QualType Ty, CharUnits Offset) {
6887 const auto *CAT =
6888 dyn_cast_or_null<ConstantArrayType>(Ty->getAsArrayTypeUnsafe());
6889 if (!CAT)
6890 return false;
6891
6892 CharUnits ElemWidth = Info.Ctx.getTypeSizeInChars(CAT->getElementType());
6893 unsigned NumInitializedElts = Val.getArrayInitializedElts();
6894 unsigned ArraySize = Val.getArraySize();
6895 // First, initialize the initialized elements.
6896 for (unsigned I = 0; I != NumInitializedElts; ++I) {
6897 const APValue &SubObj = Val.getArrayInitializedElt(I);
6898 if (!visit(SubObj, CAT->getElementType(), Offset + I * ElemWidth))
6899 return false;
6900 }
6901
6902 // Next, initialize the rest of the array using the filler.
6903 if (Val.hasArrayFiller()) {
6904 const APValue &Filler = Val.getArrayFiller();
6905 for (unsigned I = NumInitializedElts; I != ArraySize; ++I) {
6906 if (!visit(Filler, CAT->getElementType(), Offset + I * ElemWidth))
6907 return false;
6908 }
6909 }
6910
6911 return true;
6912 }
6913
visitInt(const APSInt & Val,QualType Ty,CharUnits Offset)6914 bool visitInt(const APSInt &Val, QualType Ty, CharUnits Offset) {
6915 APSInt AdjustedVal = Val;
6916 unsigned Width = AdjustedVal.getBitWidth();
6917 if (Ty->isBooleanType()) {
6918 Width = Info.Ctx.getTypeSize(Ty);
6919 AdjustedVal = AdjustedVal.extend(Width);
6920 }
6921
6922 SmallVector<unsigned char, 8> Bytes(Width / 8);
6923 llvm::StoreIntToMemory(AdjustedVal, &*Bytes.begin(), Width / 8);
6924 Buffer.writeObject(Offset, Bytes);
6925 return true;
6926 }
6927
visitFloat(const APFloat & Val,QualType Ty,CharUnits Offset)6928 bool visitFloat(const APFloat &Val, QualType Ty, CharUnits Offset) {
6929 APSInt AsInt(Val.bitcastToAPInt());
6930 return visitInt(AsInt, Ty, Offset);
6931 }
6932
6933 public:
convert(EvalInfo & Info,const APValue & Src,const CastExpr * BCE)6934 static Optional<BitCastBuffer> convert(EvalInfo &Info, const APValue &Src,
6935 const CastExpr *BCE) {
6936 CharUnits DstSize = Info.Ctx.getTypeSizeInChars(BCE->getType());
6937 APValueToBufferConverter Converter(Info, DstSize, BCE);
6938 if (!Converter.visit(Src, BCE->getSubExpr()->getType()))
6939 return None;
6940 return Converter.Buffer;
6941 }
6942 };
6943
6944 /// Write an BitCastBuffer into an APValue.
6945 class BufferToAPValueConverter {
6946 EvalInfo &Info;
6947 const BitCastBuffer &Buffer;
6948 const CastExpr *BCE;
6949
BufferToAPValueConverter(EvalInfo & Info,const BitCastBuffer & Buffer,const CastExpr * BCE)6950 BufferToAPValueConverter(EvalInfo &Info, const BitCastBuffer &Buffer,
6951 const CastExpr *BCE)
6952 : Info(Info), Buffer(Buffer), BCE(BCE) {}
6953
6954 // Emit an unsupported bit_cast type error. Sema refuses to build a bit_cast
6955 // with an invalid type, so anything left is a deficiency on our part (FIXME).
6956 // Ideally this will be unreachable.
unsupportedType(QualType Ty)6957 llvm::NoneType unsupportedType(QualType Ty) {
6958 Info.FFDiag(BCE->getBeginLoc(),
6959 diag::note_constexpr_bit_cast_unsupported_type)
6960 << Ty;
6961 return None;
6962 }
6963
unrepresentableValue(QualType Ty,const APSInt & Val)6964 llvm::NoneType unrepresentableValue(QualType Ty, const APSInt &Val) {
6965 Info.FFDiag(BCE->getBeginLoc(),
6966 diag::note_constexpr_bit_cast_unrepresentable_value)
6967 << Ty << Val.toString(/*Radix=*/10);
6968 return None;
6969 }
6970
visit(const BuiltinType * T,CharUnits Offset,const EnumType * EnumSugar=nullptr)6971 Optional<APValue> visit(const BuiltinType *T, CharUnits Offset,
6972 const EnumType *EnumSugar = nullptr) {
6973 if (T->isNullPtrType()) {
6974 uint64_t NullValue = Info.Ctx.getTargetNullPointerValue(QualType(T, 0));
6975 return APValue((Expr *)nullptr,
6976 /*Offset=*/CharUnits::fromQuantity(NullValue),
6977 APValue::NoLValuePath{}, /*IsNullPtr=*/true);
6978 }
6979
6980 CharUnits SizeOf = Info.Ctx.getTypeSizeInChars(T);
6981
6982 // Work around floating point types that contain unused padding bytes. This
6983 // is really just `long double` on x86, which is the only fundamental type
6984 // with padding bytes.
6985 if (T->isRealFloatingType()) {
6986 const llvm::fltSemantics &Semantics =
6987 Info.Ctx.getFloatTypeSemantics(QualType(T, 0));
6988 unsigned NumBits = llvm::APFloatBase::getSizeInBits(Semantics);
6989 assert(NumBits % 8 == 0);
6990 CharUnits NumBytes = CharUnits::fromQuantity(NumBits / 8);
6991 if (NumBytes != SizeOf)
6992 SizeOf = NumBytes;
6993 }
6994
6995 SmallVector<uint8_t, 8> Bytes;
6996 if (!Buffer.readObject(Offset, SizeOf, Bytes)) {
6997 // If this is std::byte or unsigned char, then its okay to store an
6998 // indeterminate value.
6999 bool IsStdByte = EnumSugar && EnumSugar->isStdByteType();
7000 bool IsUChar =
7001 !EnumSugar && (T->isSpecificBuiltinType(BuiltinType::UChar) ||
7002 T->isSpecificBuiltinType(BuiltinType::Char_U));
7003 if (!IsStdByte && !IsUChar) {
7004 QualType DisplayType(EnumSugar ? (const Type *)EnumSugar : T, 0);
7005 Info.FFDiag(BCE->getExprLoc(),
7006 diag::note_constexpr_bit_cast_indet_dest)
7007 << DisplayType << Info.Ctx.getLangOpts().CharIsSigned;
7008 return None;
7009 }
7010
7011 return APValue::IndeterminateValue();
7012 }
7013
7014 APSInt Val(SizeOf.getQuantity() * Info.Ctx.getCharWidth(), true);
7015 llvm::LoadIntFromMemory(Val, &*Bytes.begin(), Bytes.size());
7016
7017 if (T->isIntegralOrEnumerationType()) {
7018 Val.setIsSigned(T->isSignedIntegerOrEnumerationType());
7019
7020 unsigned IntWidth = Info.Ctx.getIntWidth(QualType(T, 0));
7021 if (IntWidth != Val.getBitWidth()) {
7022 APSInt Truncated = Val.trunc(IntWidth);
7023 if (Truncated.extend(Val.getBitWidth()) != Val)
7024 return unrepresentableValue(QualType(T, 0), Val);
7025 Val = Truncated;
7026 }
7027
7028 return APValue(Val);
7029 }
7030
7031 if (T->isRealFloatingType()) {
7032 const llvm::fltSemantics &Semantics =
7033 Info.Ctx.getFloatTypeSemantics(QualType(T, 0));
7034 return APValue(APFloat(Semantics, Val));
7035 }
7036
7037 return unsupportedType(QualType(T, 0));
7038 }
7039
visit(const RecordType * RTy,CharUnits Offset)7040 Optional<APValue> visit(const RecordType *RTy, CharUnits Offset) {
7041 const RecordDecl *RD = RTy->getAsRecordDecl();
7042 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
7043
7044 unsigned NumBases = 0;
7045 if (auto *CXXRD = dyn_cast<CXXRecordDecl>(RD))
7046 NumBases = CXXRD->getNumBases();
7047
7048 APValue ResultVal(APValue::UninitStruct(), NumBases,
7049 std::distance(RD->field_begin(), RD->field_end()));
7050
7051 // Visit the base classes.
7052 if (auto *CXXRD = dyn_cast<CXXRecordDecl>(RD)) {
7053 for (size_t I = 0, E = CXXRD->getNumBases(); I != E; ++I) {
7054 const CXXBaseSpecifier &BS = CXXRD->bases_begin()[I];
7055 CXXRecordDecl *BaseDecl = BS.getType()->getAsCXXRecordDecl();
7056 if (BaseDecl->isEmpty() ||
7057 Info.Ctx.getASTRecordLayout(BaseDecl).getNonVirtualSize().isZero())
7058 continue;
7059
7060 Optional<APValue> SubObj = visitType(
7061 BS.getType(), Layout.getBaseClassOffset(BaseDecl) + Offset);
7062 if (!SubObj)
7063 return None;
7064 ResultVal.getStructBase(I) = *SubObj;
7065 }
7066 }
7067
7068 // Visit the fields.
7069 unsigned FieldIdx = 0;
7070 for (FieldDecl *FD : RD->fields()) {
7071 // FIXME: We don't currently support bit-fields. A lot of the logic for
7072 // this is in CodeGen, so we need to factor it around.
7073 if (FD->isBitField()) {
7074 Info.FFDiag(BCE->getBeginLoc(),
7075 diag::note_constexpr_bit_cast_unsupported_bitfield);
7076 return None;
7077 }
7078
7079 uint64_t FieldOffsetBits = Layout.getFieldOffset(FieldIdx);
7080 assert(FieldOffsetBits % Info.Ctx.getCharWidth() == 0);
7081
7082 CharUnits FieldOffset =
7083 CharUnits::fromQuantity(FieldOffsetBits / Info.Ctx.getCharWidth()) +
7084 Offset;
7085 QualType FieldTy = FD->getType();
7086 Optional<APValue> SubObj = visitType(FieldTy, FieldOffset);
7087 if (!SubObj)
7088 return None;
7089 ResultVal.getStructField(FieldIdx) = *SubObj;
7090 ++FieldIdx;
7091 }
7092
7093 return ResultVal;
7094 }
7095
visit(const EnumType * Ty,CharUnits Offset)7096 Optional<APValue> visit(const EnumType *Ty, CharUnits Offset) {
7097 QualType RepresentationType = Ty->getDecl()->getIntegerType();
7098 assert(!RepresentationType.isNull() &&
7099 "enum forward decl should be caught by Sema");
7100 const auto *AsBuiltin =
7101 RepresentationType.getCanonicalType()->castAs<BuiltinType>();
7102 // Recurse into the underlying type. Treat std::byte transparently as
7103 // unsigned char.
7104 return visit(AsBuiltin, Offset, /*EnumTy=*/Ty);
7105 }
7106
visit(const ConstantArrayType * Ty,CharUnits Offset)7107 Optional<APValue> visit(const ConstantArrayType *Ty, CharUnits Offset) {
7108 size_t Size = Ty->getSize().getLimitedValue();
7109 CharUnits ElementWidth = Info.Ctx.getTypeSizeInChars(Ty->getElementType());
7110
7111 APValue ArrayValue(APValue::UninitArray(), Size, Size);
7112 for (size_t I = 0; I != Size; ++I) {
7113 Optional<APValue> ElementValue =
7114 visitType(Ty->getElementType(), Offset + I * ElementWidth);
7115 if (!ElementValue)
7116 return None;
7117 ArrayValue.getArrayInitializedElt(I) = std::move(*ElementValue);
7118 }
7119
7120 return ArrayValue;
7121 }
7122
visit(const Type * Ty,CharUnits Offset)7123 Optional<APValue> visit(const Type *Ty, CharUnits Offset) {
7124 return unsupportedType(QualType(Ty, 0));
7125 }
7126
visitType(QualType Ty,CharUnits Offset)7127 Optional<APValue> visitType(QualType Ty, CharUnits Offset) {
7128 QualType Can = Ty.getCanonicalType();
7129
7130 switch (Can->getTypeClass()) {
7131 #define TYPE(Class, Base) \
7132 case Type::Class: \
7133 return visit(cast<Class##Type>(Can.getTypePtr()), Offset);
7134 #define ABSTRACT_TYPE(Class, Base)
7135 #define NON_CANONICAL_TYPE(Class, Base) \
7136 case Type::Class: \
7137 llvm_unreachable("non-canonical type should be impossible!");
7138 #define DEPENDENT_TYPE(Class, Base) \
7139 case Type::Class: \
7140 llvm_unreachable( \
7141 "dependent types aren't supported in the constant evaluator!");
7142 #define NON_CANONICAL_UNLESS_DEPENDENT(Class, Base) \
7143 case Type::Class: \
7144 llvm_unreachable("either dependent or not canonical!");
7145 #include "clang/AST/TypeNodes.inc"
7146 }
7147 llvm_unreachable("Unhandled Type::TypeClass");
7148 }
7149
7150 public:
7151 // Pull out a full value of type DstType.
convert(EvalInfo & Info,BitCastBuffer & Buffer,const CastExpr * BCE)7152 static Optional<APValue> convert(EvalInfo &Info, BitCastBuffer &Buffer,
7153 const CastExpr *BCE) {
7154 BufferToAPValueConverter Converter(Info, Buffer, BCE);
7155 return Converter.visitType(BCE->getType(), CharUnits::fromQuantity(0));
7156 }
7157 };
7158
checkBitCastConstexprEligibilityType(SourceLocation Loc,QualType Ty,EvalInfo * Info,const ASTContext & Ctx,bool CheckingDest)7159 static bool checkBitCastConstexprEligibilityType(SourceLocation Loc,
7160 QualType Ty, EvalInfo *Info,
7161 const ASTContext &Ctx,
7162 bool CheckingDest) {
7163 Ty = Ty.getCanonicalType();
7164
7165 auto diag = [&](int Reason) {
7166 if (Info)
7167 Info->FFDiag(Loc, diag::note_constexpr_bit_cast_invalid_type)
7168 << CheckingDest << (Reason == 4) << Reason;
7169 return false;
7170 };
7171 auto note = [&](int Construct, QualType NoteTy, SourceLocation NoteLoc) {
7172 if (Info)
7173 Info->Note(NoteLoc, diag::note_constexpr_bit_cast_invalid_subtype)
7174 << NoteTy << Construct << Ty;
7175 return false;
7176 };
7177
7178 if (Ty->isUnionType())
7179 return diag(0);
7180 if (Ty->isPointerType())
7181 return diag(1);
7182 if (Ty->isMemberPointerType())
7183 return diag(2);
7184 if (Ty.isVolatileQualified())
7185 return diag(3);
7186
7187 if (RecordDecl *Record = Ty->getAsRecordDecl()) {
7188 if (auto *CXXRD = dyn_cast<CXXRecordDecl>(Record)) {
7189 for (CXXBaseSpecifier &BS : CXXRD->bases())
7190 if (!checkBitCastConstexprEligibilityType(Loc, BS.getType(), Info, Ctx,
7191 CheckingDest))
7192 return note(1, BS.getType(), BS.getBeginLoc());
7193 }
7194 for (FieldDecl *FD : Record->fields()) {
7195 if (FD->getType()->isReferenceType())
7196 return diag(4);
7197 if (!checkBitCastConstexprEligibilityType(Loc, FD->getType(), Info, Ctx,
7198 CheckingDest))
7199 return note(0, FD->getType(), FD->getBeginLoc());
7200 }
7201 }
7202
7203 if (Ty->isArrayType() &&
7204 !checkBitCastConstexprEligibilityType(Loc, Ctx.getBaseElementType(Ty),
7205 Info, Ctx, CheckingDest))
7206 return false;
7207
7208 return true;
7209 }
7210
checkBitCastConstexprEligibility(EvalInfo * Info,const ASTContext & Ctx,const CastExpr * BCE)7211 static bool checkBitCastConstexprEligibility(EvalInfo *Info,
7212 const ASTContext &Ctx,
7213 const CastExpr *BCE) {
7214 bool DestOK = checkBitCastConstexprEligibilityType(
7215 BCE->getBeginLoc(), BCE->getType(), Info, Ctx, true);
7216 bool SourceOK = DestOK && checkBitCastConstexprEligibilityType(
7217 BCE->getBeginLoc(),
7218 BCE->getSubExpr()->getType(), Info, Ctx, false);
7219 return SourceOK;
7220 }
7221
handleLValueToRValueBitCast(EvalInfo & Info,APValue & DestValue,APValue & SourceValue,const CastExpr * BCE)7222 static bool handleLValueToRValueBitCast(EvalInfo &Info, APValue &DestValue,
7223 APValue &SourceValue,
7224 const CastExpr *BCE) {
7225 assert(CHAR_BIT == 8 && Info.Ctx.getTargetInfo().getCharWidth() == 8 &&
7226 "no host or target supports non 8-bit chars");
7227 assert(SourceValue.isLValue() &&
7228 "LValueToRValueBitcast requires an lvalue operand!");
7229
7230 if (!checkBitCastConstexprEligibility(&Info, Info.Ctx, BCE))
7231 return false;
7232
7233 LValue SourceLValue;
7234 APValue SourceRValue;
7235 SourceLValue.setFrom(Info.Ctx, SourceValue);
7236 if (!handleLValueToRValueConversion(
7237 Info, BCE, BCE->getSubExpr()->getType().withConst(), SourceLValue,
7238 SourceRValue, /*WantObjectRepresentation=*/true))
7239 return false;
7240
7241 // Read out SourceValue into a char buffer.
7242 Optional<BitCastBuffer> Buffer =
7243 APValueToBufferConverter::convert(Info, SourceRValue, BCE);
7244 if (!Buffer)
7245 return false;
7246
7247 // Write out the buffer into a new APValue.
7248 Optional<APValue> MaybeDestValue =
7249 BufferToAPValueConverter::convert(Info, *Buffer, BCE);
7250 if (!MaybeDestValue)
7251 return false;
7252
7253 DestValue = std::move(*MaybeDestValue);
7254 return true;
7255 }
7256
7257 template <class Derived>
7258 class ExprEvaluatorBase
7259 : public ConstStmtVisitor<Derived, bool> {
7260 private:
getDerived()7261 Derived &getDerived() { return static_cast<Derived&>(*this); }
DerivedSuccess(const APValue & V,const Expr * E)7262 bool DerivedSuccess(const APValue &V, const Expr *E) {
7263 return getDerived().Success(V, E);
7264 }
DerivedZeroInitialization(const Expr * E)7265 bool DerivedZeroInitialization(const Expr *E) {
7266 return getDerived().ZeroInitialization(E);
7267 }
7268
7269 // Check whether a conditional operator with a non-constant condition is a
7270 // potential constant expression. If neither arm is a potential constant
7271 // expression, then the conditional operator is not either.
7272 template<typename ConditionalOperator>
CheckPotentialConstantConditional(const ConditionalOperator * E)7273 void CheckPotentialConstantConditional(const ConditionalOperator *E) {
7274 assert(Info.checkingPotentialConstantExpression());
7275
7276 // Speculatively evaluate both arms.
7277 SmallVector<PartialDiagnosticAt, 8> Diag;
7278 {
7279 SpeculativeEvaluationRAII Speculate(Info, &Diag);
7280 StmtVisitorTy::Visit(E->getFalseExpr());
7281 if (Diag.empty())
7282 return;
7283 }
7284
7285 {
7286 SpeculativeEvaluationRAII Speculate(Info, &Diag);
7287 Diag.clear();
7288 StmtVisitorTy::Visit(E->getTrueExpr());
7289 if (Diag.empty())
7290 return;
7291 }
7292
7293 Error(E, diag::note_constexpr_conditional_never_const);
7294 }
7295
7296
7297 template<typename ConditionalOperator>
HandleConditionalOperator(const ConditionalOperator * E)7298 bool HandleConditionalOperator(const ConditionalOperator *E) {
7299 bool BoolResult;
7300 if (!EvaluateAsBooleanCondition(E->getCond(), BoolResult, Info)) {
7301 if (Info.checkingPotentialConstantExpression() && Info.noteFailure()) {
7302 CheckPotentialConstantConditional(E);
7303 return false;
7304 }
7305 if (Info.noteFailure()) {
7306 StmtVisitorTy::Visit(E->getTrueExpr());
7307 StmtVisitorTy::Visit(E->getFalseExpr());
7308 }
7309 return false;
7310 }
7311
7312 Expr *EvalExpr = BoolResult ? E->getTrueExpr() : E->getFalseExpr();
7313 return StmtVisitorTy::Visit(EvalExpr);
7314 }
7315
7316 protected:
7317 EvalInfo &Info;
7318 typedef ConstStmtVisitor<Derived, bool> StmtVisitorTy;
7319 typedef ExprEvaluatorBase ExprEvaluatorBaseTy;
7320
CCEDiag(const Expr * E,diag::kind D)7321 OptionalDiagnostic CCEDiag(const Expr *E, diag::kind D) {
7322 return Info.CCEDiag(E, D);
7323 }
7324
ZeroInitialization(const Expr * E)7325 bool ZeroInitialization(const Expr *E) { return Error(E); }
7326
7327 public:
ExprEvaluatorBase(EvalInfo & Info)7328 ExprEvaluatorBase(EvalInfo &Info) : Info(Info) {}
7329
getEvalInfo()7330 EvalInfo &getEvalInfo() { return Info; }
7331
7332 /// Report an evaluation error. This should only be called when an error is
7333 /// first discovered. When propagating an error, just return false.
Error(const Expr * E,diag::kind D)7334 bool Error(const Expr *E, diag::kind D) {
7335 Info.FFDiag(E, D);
7336 return false;
7337 }
Error(const Expr * E)7338 bool Error(const Expr *E) {
7339 return Error(E, diag::note_invalid_subexpr_in_const_expr);
7340 }
7341
VisitStmt(const Stmt *)7342 bool VisitStmt(const Stmt *) {
7343 llvm_unreachable("Expression evaluator should not be called on stmts");
7344 }
VisitExpr(const Expr * E)7345 bool VisitExpr(const Expr *E) {
7346 return Error(E);
7347 }
7348
VisitConstantExpr(const ConstantExpr * E)7349 bool VisitConstantExpr(const ConstantExpr *E) {
7350 if (E->hasAPValueResult())
7351 return DerivedSuccess(E->getAPValueResult(), E);
7352
7353 return StmtVisitorTy::Visit(E->getSubExpr());
7354 }
7355
VisitParenExpr(const ParenExpr * E)7356 bool VisitParenExpr(const ParenExpr *E)
7357 { return StmtVisitorTy::Visit(E->getSubExpr()); }
VisitUnaryExtension(const UnaryOperator * E)7358 bool VisitUnaryExtension(const UnaryOperator *E)
7359 { return StmtVisitorTy::Visit(E->getSubExpr()); }
VisitUnaryPlus(const UnaryOperator * E)7360 bool VisitUnaryPlus(const UnaryOperator *E)
7361 { return StmtVisitorTy::Visit(E->getSubExpr()); }
VisitChooseExpr(const ChooseExpr * E)7362 bool VisitChooseExpr(const ChooseExpr *E)
7363 { return StmtVisitorTy::Visit(E->getChosenSubExpr()); }
VisitGenericSelectionExpr(const GenericSelectionExpr * E)7364 bool VisitGenericSelectionExpr(const GenericSelectionExpr *E)
7365 { return StmtVisitorTy::Visit(E->getResultExpr()); }
VisitSubstNonTypeTemplateParmExpr(const SubstNonTypeTemplateParmExpr * E)7366 bool VisitSubstNonTypeTemplateParmExpr(const SubstNonTypeTemplateParmExpr *E)
7367 { return StmtVisitorTy::Visit(E->getReplacement()); }
VisitCXXDefaultArgExpr(const CXXDefaultArgExpr * E)7368 bool VisitCXXDefaultArgExpr(const CXXDefaultArgExpr *E) {
7369 TempVersionRAII RAII(*Info.CurrentCall);
7370 SourceLocExprScopeGuard Guard(E, Info.CurrentCall->CurSourceLocExprScope);
7371 return StmtVisitorTy::Visit(E->getExpr());
7372 }
VisitCXXDefaultInitExpr(const CXXDefaultInitExpr * E)7373 bool VisitCXXDefaultInitExpr(const CXXDefaultInitExpr *E) {
7374 TempVersionRAII RAII(*Info.CurrentCall);
7375 // The initializer may not have been parsed yet, or might be erroneous.
7376 if (!E->getExpr())
7377 return Error(E);
7378 SourceLocExprScopeGuard Guard(E, Info.CurrentCall->CurSourceLocExprScope);
7379 return StmtVisitorTy::Visit(E->getExpr());
7380 }
7381
VisitExprWithCleanups(const ExprWithCleanups * E)7382 bool VisitExprWithCleanups(const ExprWithCleanups *E) {
7383 FullExpressionRAII Scope(Info);
7384 return StmtVisitorTy::Visit(E->getSubExpr()) && Scope.destroy();
7385 }
7386
7387 // Temporaries are registered when created, so we don't care about
7388 // CXXBindTemporaryExpr.
VisitCXXBindTemporaryExpr(const CXXBindTemporaryExpr * E)7389 bool VisitCXXBindTemporaryExpr(const CXXBindTemporaryExpr *E) {
7390 return StmtVisitorTy::Visit(E->getSubExpr());
7391 }
7392
VisitCXXReinterpretCastExpr(const CXXReinterpretCastExpr * E)7393 bool VisitCXXReinterpretCastExpr(const CXXReinterpretCastExpr *E) {
7394 CCEDiag(E, diag::note_constexpr_invalid_cast) << 0;
7395 return static_cast<Derived*>(this)->VisitCastExpr(E);
7396 }
VisitCXXDynamicCastExpr(const CXXDynamicCastExpr * E)7397 bool VisitCXXDynamicCastExpr(const CXXDynamicCastExpr *E) {
7398 if (!Info.Ctx.getLangOpts().CPlusPlus20)
7399 CCEDiag(E, diag::note_constexpr_invalid_cast) << 1;
7400 return static_cast<Derived*>(this)->VisitCastExpr(E);
7401 }
VisitBuiltinBitCastExpr(const BuiltinBitCastExpr * E)7402 bool VisitBuiltinBitCastExpr(const BuiltinBitCastExpr *E) {
7403 return static_cast<Derived*>(this)->VisitCastExpr(E);
7404 }
7405
VisitBinaryOperator(const BinaryOperator * E)7406 bool VisitBinaryOperator(const BinaryOperator *E) {
7407 switch (E->getOpcode()) {
7408 default:
7409 return Error(E);
7410
7411 case BO_Comma:
7412 VisitIgnoredValue(E->getLHS());
7413 return StmtVisitorTy::Visit(E->getRHS());
7414
7415 case BO_PtrMemD:
7416 case BO_PtrMemI: {
7417 LValue Obj;
7418 if (!HandleMemberPointerAccess(Info, E, Obj))
7419 return false;
7420 APValue Result;
7421 if (!handleLValueToRValueConversion(Info, E, E->getType(), Obj, Result))
7422 return false;
7423 return DerivedSuccess(Result, E);
7424 }
7425 }
7426 }
7427
VisitCXXRewrittenBinaryOperator(const CXXRewrittenBinaryOperator * E)7428 bool VisitCXXRewrittenBinaryOperator(const CXXRewrittenBinaryOperator *E) {
7429 return StmtVisitorTy::Visit(E->getSemanticForm());
7430 }
7431
VisitBinaryConditionalOperator(const BinaryConditionalOperator * E)7432 bool VisitBinaryConditionalOperator(const BinaryConditionalOperator *E) {
7433 // Evaluate and cache the common expression. We treat it as a temporary,
7434 // even though it's not quite the same thing.
7435 LValue CommonLV;
7436 if (!Evaluate(Info.CurrentCall->createTemporary(
7437 E->getOpaqueValue(),
7438 getStorageType(Info.Ctx, E->getOpaqueValue()),
7439 ScopeKind::FullExpression, CommonLV),
7440 Info, E->getCommon()))
7441 return false;
7442
7443 return HandleConditionalOperator(E);
7444 }
7445
VisitConditionalOperator(const ConditionalOperator * E)7446 bool VisitConditionalOperator(const ConditionalOperator *E) {
7447 bool IsBcpCall = false;
7448 // If the condition (ignoring parens) is a __builtin_constant_p call,
7449 // the result is a constant expression if it can be folded without
7450 // side-effects. This is an important GNU extension. See GCC PR38377
7451 // for discussion.
7452 if (const CallExpr *CallCE =
7453 dyn_cast<CallExpr>(E->getCond()->IgnoreParenCasts()))
7454 if (CallCE->getBuiltinCallee() == Builtin::BI__builtin_constant_p)
7455 IsBcpCall = true;
7456
7457 // Always assume __builtin_constant_p(...) ? ... : ... is a potential
7458 // constant expression; we can't check whether it's potentially foldable.
7459 // FIXME: We should instead treat __builtin_constant_p as non-constant if
7460 // it would return 'false' in this mode.
7461 if (Info.checkingPotentialConstantExpression() && IsBcpCall)
7462 return false;
7463
7464 FoldConstant Fold(Info, IsBcpCall);
7465 if (!HandleConditionalOperator(E)) {
7466 Fold.keepDiagnostics();
7467 return false;
7468 }
7469
7470 return true;
7471 }
7472
VisitOpaqueValueExpr(const OpaqueValueExpr * E)7473 bool VisitOpaqueValueExpr(const OpaqueValueExpr *E) {
7474 if (APValue *Value = Info.CurrentCall->getCurrentTemporary(E))
7475 return DerivedSuccess(*Value, E);
7476
7477 const Expr *Source = E->getSourceExpr();
7478 if (!Source)
7479 return Error(E);
7480 if (Source == E) { // sanity checking.
7481 assert(0 && "OpaqueValueExpr recursively refers to itself");
7482 return Error(E);
7483 }
7484 return StmtVisitorTy::Visit(Source);
7485 }
7486
VisitPseudoObjectExpr(const PseudoObjectExpr * E)7487 bool VisitPseudoObjectExpr(const PseudoObjectExpr *E) {
7488 for (const Expr *SemE : E->semantics()) {
7489 if (auto *OVE = dyn_cast<OpaqueValueExpr>(SemE)) {
7490 // FIXME: We can't handle the case where an OpaqueValueExpr is also the
7491 // result expression: there could be two different LValues that would
7492 // refer to the same object in that case, and we can't model that.
7493 if (SemE == E->getResultExpr())
7494 return Error(E);
7495
7496 // Unique OVEs get evaluated if and when we encounter them when
7497 // emitting the rest of the semantic form, rather than eagerly.
7498 if (OVE->isUnique())
7499 continue;
7500
7501 LValue LV;
7502 if (!Evaluate(Info.CurrentCall->createTemporary(
7503 OVE, getStorageType(Info.Ctx, OVE),
7504 ScopeKind::FullExpression, LV),
7505 Info, OVE->getSourceExpr()))
7506 return false;
7507 } else if (SemE == E->getResultExpr()) {
7508 if (!StmtVisitorTy::Visit(SemE))
7509 return false;
7510 } else {
7511 if (!EvaluateIgnoredValue(Info, SemE))
7512 return false;
7513 }
7514 }
7515 return true;
7516 }
7517
VisitCallExpr(const CallExpr * E)7518 bool VisitCallExpr(const CallExpr *E) {
7519 APValue Result;
7520 if (!handleCallExpr(E, Result, nullptr))
7521 return false;
7522 return DerivedSuccess(Result, E);
7523 }
7524
handleCallExpr(const CallExpr * E,APValue & Result,const LValue * ResultSlot)7525 bool handleCallExpr(const CallExpr *E, APValue &Result,
7526 const LValue *ResultSlot) {
7527 CallScopeRAII CallScope(Info);
7528
7529 const Expr *Callee = E->getCallee()->IgnoreParens();
7530 QualType CalleeType = Callee->getType();
7531
7532 const FunctionDecl *FD = nullptr;
7533 LValue *This = nullptr, ThisVal;
7534 auto Args = llvm::makeArrayRef(E->getArgs(), E->getNumArgs());
7535 bool HasQualifier = false;
7536
7537 CallRef Call;
7538
7539 // Extract function decl and 'this' pointer from the callee.
7540 if (CalleeType->isSpecificBuiltinType(BuiltinType::BoundMember)) {
7541 const CXXMethodDecl *Member = nullptr;
7542 if (const MemberExpr *ME = dyn_cast<MemberExpr>(Callee)) {
7543 // Explicit bound member calls, such as x.f() or p->g();
7544 if (!EvaluateObjectArgument(Info, ME->getBase(), ThisVal))
7545 return false;
7546 Member = dyn_cast<CXXMethodDecl>(ME->getMemberDecl());
7547 if (!Member)
7548 return Error(Callee);
7549 This = &ThisVal;
7550 HasQualifier = ME->hasQualifier();
7551 } else if (const BinaryOperator *BE = dyn_cast<BinaryOperator>(Callee)) {
7552 // Indirect bound member calls ('.*' or '->*').
7553 const ValueDecl *D =
7554 HandleMemberPointerAccess(Info, BE, ThisVal, false);
7555 if (!D)
7556 return false;
7557 Member = dyn_cast<CXXMethodDecl>(D);
7558 if (!Member)
7559 return Error(Callee);
7560 This = &ThisVal;
7561 } else if (const auto *PDE = dyn_cast<CXXPseudoDestructorExpr>(Callee)) {
7562 if (!Info.getLangOpts().CPlusPlus20)
7563 Info.CCEDiag(PDE, diag::note_constexpr_pseudo_destructor);
7564 return EvaluateObjectArgument(Info, PDE->getBase(), ThisVal) &&
7565 HandleDestruction(Info, PDE, ThisVal, PDE->getDestroyedType());
7566 } else
7567 return Error(Callee);
7568 FD = Member;
7569 } else if (CalleeType->isFunctionPointerType()) {
7570 LValue CalleeLV;
7571 if (!EvaluatePointer(Callee, CalleeLV, Info))
7572 return false;
7573
7574 if (!CalleeLV.getLValueOffset().isZero())
7575 return Error(Callee);
7576 FD = dyn_cast_or_null<FunctionDecl>(
7577 CalleeLV.getLValueBase().dyn_cast<const ValueDecl *>());
7578 if (!FD)
7579 return Error(Callee);
7580 // Don't call function pointers which have been cast to some other type.
7581 // Per DR (no number yet), the caller and callee can differ in noexcept.
7582 if (!Info.Ctx.hasSameFunctionTypeIgnoringExceptionSpec(
7583 CalleeType->getPointeeType(), FD->getType())) {
7584 return Error(E);
7585 }
7586
7587 // For an (overloaded) assignment expression, evaluate the RHS before the
7588 // LHS.
7589 auto *OCE = dyn_cast<CXXOperatorCallExpr>(E);
7590 if (OCE && OCE->isAssignmentOp()) {
7591 assert(Args.size() == 2 && "wrong number of arguments in assignment");
7592 Call = Info.CurrentCall->createCall(FD);
7593 if (!EvaluateArgs(isa<CXXMethodDecl>(FD) ? Args.slice(1) : Args, Call,
7594 Info, FD, /*RightToLeft=*/true))
7595 return false;
7596 }
7597
7598 // Overloaded operator calls to member functions are represented as normal
7599 // calls with '*this' as the first argument.
7600 const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD);
7601 if (MD && !MD->isStatic()) {
7602 // FIXME: When selecting an implicit conversion for an overloaded
7603 // operator delete, we sometimes try to evaluate calls to conversion
7604 // operators without a 'this' parameter!
7605 if (Args.empty())
7606 return Error(E);
7607
7608 if (!EvaluateObjectArgument(Info, Args[0], ThisVal))
7609 return false;
7610 This = &ThisVal;
7611 Args = Args.slice(1);
7612 } else if (MD && MD->isLambdaStaticInvoker()) {
7613 // Map the static invoker for the lambda back to the call operator.
7614 // Conveniently, we don't have to slice out the 'this' argument (as is
7615 // being done for the non-static case), since a static member function
7616 // doesn't have an implicit argument passed in.
7617 const CXXRecordDecl *ClosureClass = MD->getParent();
7618 assert(
7619 ClosureClass->captures_begin() == ClosureClass->captures_end() &&
7620 "Number of captures must be zero for conversion to function-ptr");
7621
7622 const CXXMethodDecl *LambdaCallOp =
7623 ClosureClass->getLambdaCallOperator();
7624
7625 // Set 'FD', the function that will be called below, to the call
7626 // operator. If the closure object represents a generic lambda, find
7627 // the corresponding specialization of the call operator.
7628
7629 if (ClosureClass->isGenericLambda()) {
7630 assert(MD->isFunctionTemplateSpecialization() &&
7631 "A generic lambda's static-invoker function must be a "
7632 "template specialization");
7633 const TemplateArgumentList *TAL = MD->getTemplateSpecializationArgs();
7634 FunctionTemplateDecl *CallOpTemplate =
7635 LambdaCallOp->getDescribedFunctionTemplate();
7636 void *InsertPos = nullptr;
7637 FunctionDecl *CorrespondingCallOpSpecialization =
7638 CallOpTemplate->findSpecialization(TAL->asArray(), InsertPos);
7639 assert(CorrespondingCallOpSpecialization &&
7640 "We must always have a function call operator specialization "
7641 "that corresponds to our static invoker specialization");
7642 FD = cast<CXXMethodDecl>(CorrespondingCallOpSpecialization);
7643 } else
7644 FD = LambdaCallOp;
7645 } else if (FD->isReplaceableGlobalAllocationFunction()) {
7646 if (FD->getDeclName().getCXXOverloadedOperator() == OO_New ||
7647 FD->getDeclName().getCXXOverloadedOperator() == OO_Array_New) {
7648 LValue Ptr;
7649 if (!HandleOperatorNewCall(Info, E, Ptr))
7650 return false;
7651 Ptr.moveInto(Result);
7652 return CallScope.destroy();
7653 } else {
7654 return HandleOperatorDeleteCall(Info, E) && CallScope.destroy();
7655 }
7656 }
7657 } else
7658 return Error(E);
7659
7660 // Evaluate the arguments now if we've not already done so.
7661 if (!Call) {
7662 Call = Info.CurrentCall->createCall(FD);
7663 if (!EvaluateArgs(Args, Call, Info, FD))
7664 return false;
7665 }
7666
7667 SmallVector<QualType, 4> CovariantAdjustmentPath;
7668 if (This) {
7669 auto *NamedMember = dyn_cast<CXXMethodDecl>(FD);
7670 if (NamedMember && NamedMember->isVirtual() && !HasQualifier) {
7671 // Perform virtual dispatch, if necessary.
7672 FD = HandleVirtualDispatch(Info, E, *This, NamedMember,
7673 CovariantAdjustmentPath);
7674 if (!FD)
7675 return false;
7676 } else {
7677 // Check that the 'this' pointer points to an object of the right type.
7678 // FIXME: If this is an assignment operator call, we may need to change
7679 // the active union member before we check this.
7680 if (!checkNonVirtualMemberCallThisPointer(Info, E, *This, NamedMember))
7681 return false;
7682 }
7683 }
7684
7685 // Destructor calls are different enough that they have their own codepath.
7686 if (auto *DD = dyn_cast<CXXDestructorDecl>(FD)) {
7687 assert(This && "no 'this' pointer for destructor call");
7688 return HandleDestruction(Info, E, *This,
7689 Info.Ctx.getRecordType(DD->getParent())) &&
7690 CallScope.destroy();
7691 }
7692
7693 const FunctionDecl *Definition = nullptr;
7694 Stmt *Body = FD->getBody(Definition);
7695
7696 if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition, Body) ||
7697 !HandleFunctionCall(E->getExprLoc(), Definition, This, Args, Call,
7698 Body, Info, Result, ResultSlot))
7699 return false;
7700
7701 if (!CovariantAdjustmentPath.empty() &&
7702 !HandleCovariantReturnAdjustment(Info, E, Result,
7703 CovariantAdjustmentPath))
7704 return false;
7705
7706 return CallScope.destroy();
7707 }
7708
VisitCompoundLiteralExpr(const CompoundLiteralExpr * E)7709 bool VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) {
7710 return StmtVisitorTy::Visit(E->getInitializer());
7711 }
VisitInitListExpr(const InitListExpr * E)7712 bool VisitInitListExpr(const InitListExpr *E) {
7713 if (E->getNumInits() == 0)
7714 return DerivedZeroInitialization(E);
7715 if (E->getNumInits() == 1)
7716 return StmtVisitorTy::Visit(E->getInit(0));
7717 return Error(E);
7718 }
VisitImplicitValueInitExpr(const ImplicitValueInitExpr * E)7719 bool VisitImplicitValueInitExpr(const ImplicitValueInitExpr *E) {
7720 return DerivedZeroInitialization(E);
7721 }
VisitCXXScalarValueInitExpr(const CXXScalarValueInitExpr * E)7722 bool VisitCXXScalarValueInitExpr(const CXXScalarValueInitExpr *E) {
7723 return DerivedZeroInitialization(E);
7724 }
VisitCXXNullPtrLiteralExpr(const CXXNullPtrLiteralExpr * E)7725 bool VisitCXXNullPtrLiteralExpr(const CXXNullPtrLiteralExpr *E) {
7726 return DerivedZeroInitialization(E);
7727 }
7728
7729 /// A member expression where the object is a prvalue is itself a prvalue.
VisitMemberExpr(const MemberExpr * E)7730 bool VisitMemberExpr(const MemberExpr *E) {
7731 assert(!Info.Ctx.getLangOpts().CPlusPlus11 &&
7732 "missing temporary materialization conversion");
7733 assert(!E->isArrow() && "missing call to bound member function?");
7734
7735 APValue Val;
7736 if (!Evaluate(Val, Info, E->getBase()))
7737 return false;
7738
7739 QualType BaseTy = E->getBase()->getType();
7740
7741 const FieldDecl *FD = dyn_cast<FieldDecl>(E->getMemberDecl());
7742 if (!FD) return Error(E);
7743 assert(!FD->getType()->isReferenceType() && "prvalue reference?");
7744 assert(BaseTy->castAs<RecordType>()->getDecl()->getCanonicalDecl() ==
7745 FD->getParent()->getCanonicalDecl() && "record / field mismatch");
7746
7747 // Note: there is no lvalue base here. But this case should only ever
7748 // happen in C or in C++98, where we cannot be evaluating a constexpr
7749 // constructor, which is the only case the base matters.
7750 CompleteObject Obj(APValue::LValueBase(), &Val, BaseTy);
7751 SubobjectDesignator Designator(BaseTy);
7752 Designator.addDeclUnchecked(FD);
7753
7754 APValue Result;
7755 return extractSubobject(Info, E, Obj, Designator, Result) &&
7756 DerivedSuccess(Result, E);
7757 }
7758
VisitExtVectorElementExpr(const ExtVectorElementExpr * E)7759 bool VisitExtVectorElementExpr(const ExtVectorElementExpr *E) {
7760 APValue Val;
7761 if (!Evaluate(Val, Info, E->getBase()))
7762 return false;
7763
7764 if (Val.isVector()) {
7765 SmallVector<uint32_t, 4> Indices;
7766 E->getEncodedElementAccess(Indices);
7767 if (Indices.size() == 1) {
7768 // Return scalar.
7769 return DerivedSuccess(Val.getVectorElt(Indices[0]), E);
7770 } else {
7771 // Construct new APValue vector.
7772 SmallVector<APValue, 4> Elts;
7773 for (unsigned I = 0; I < Indices.size(); ++I) {
7774 Elts.push_back(Val.getVectorElt(Indices[I]));
7775 }
7776 APValue VecResult(Elts.data(), Indices.size());
7777 return DerivedSuccess(VecResult, E);
7778 }
7779 }
7780
7781 return false;
7782 }
7783
VisitCastExpr(const CastExpr * E)7784 bool VisitCastExpr(const CastExpr *E) {
7785 switch (E->getCastKind()) {
7786 default:
7787 break;
7788
7789 case CK_AtomicToNonAtomic: {
7790 APValue AtomicVal;
7791 // This does not need to be done in place even for class/array types:
7792 // atomic-to-non-atomic conversion implies copying the object
7793 // representation.
7794 if (!Evaluate(AtomicVal, Info, E->getSubExpr()))
7795 return false;
7796 return DerivedSuccess(AtomicVal, E);
7797 }
7798
7799 case CK_NoOp:
7800 case CK_UserDefinedConversion:
7801 return StmtVisitorTy::Visit(E->getSubExpr());
7802
7803 case CK_LValueToRValue: {
7804 LValue LVal;
7805 if (!EvaluateLValue(E->getSubExpr(), LVal, Info))
7806 return false;
7807 APValue RVal;
7808 // Note, we use the subexpression's type in order to retain cv-qualifiers.
7809 if (!handleLValueToRValueConversion(Info, E, E->getSubExpr()->getType(),
7810 LVal, RVal))
7811 return false;
7812 return DerivedSuccess(RVal, E);
7813 }
7814 case CK_LValueToRValueBitCast: {
7815 APValue DestValue, SourceValue;
7816 if (!Evaluate(SourceValue, Info, E->getSubExpr()))
7817 return false;
7818 if (!handleLValueToRValueBitCast(Info, DestValue, SourceValue, E))
7819 return false;
7820 return DerivedSuccess(DestValue, E);
7821 }
7822
7823 case CK_AddressSpaceConversion: {
7824 APValue Value;
7825 if (!Evaluate(Value, Info, E->getSubExpr()))
7826 return false;
7827 return DerivedSuccess(Value, E);
7828 }
7829 }
7830
7831 return Error(E);
7832 }
7833
VisitUnaryPostInc(const UnaryOperator * UO)7834 bool VisitUnaryPostInc(const UnaryOperator *UO) {
7835 return VisitUnaryPostIncDec(UO);
7836 }
VisitUnaryPostDec(const UnaryOperator * UO)7837 bool VisitUnaryPostDec(const UnaryOperator *UO) {
7838 return VisitUnaryPostIncDec(UO);
7839 }
VisitUnaryPostIncDec(const UnaryOperator * UO)7840 bool VisitUnaryPostIncDec(const UnaryOperator *UO) {
7841 if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure())
7842 return Error(UO);
7843
7844 LValue LVal;
7845 if (!EvaluateLValue(UO->getSubExpr(), LVal, Info))
7846 return false;
7847 APValue RVal;
7848 if (!handleIncDec(this->Info, UO, LVal, UO->getSubExpr()->getType(),
7849 UO->isIncrementOp(), &RVal))
7850 return false;
7851 return DerivedSuccess(RVal, UO);
7852 }
7853
VisitStmtExpr(const StmtExpr * E)7854 bool VisitStmtExpr(const StmtExpr *E) {
7855 // We will have checked the full-expressions inside the statement expression
7856 // when they were completed, and don't need to check them again now.
7857 llvm::SaveAndRestore<bool> NotCheckingForUB(
7858 Info.CheckingForUndefinedBehavior, false);
7859
7860 const CompoundStmt *CS = E->getSubStmt();
7861 if (CS->body_empty())
7862 return true;
7863
7864 BlockScopeRAII Scope(Info);
7865 for (CompoundStmt::const_body_iterator BI = CS->body_begin(),
7866 BE = CS->body_end();
7867 /**/; ++BI) {
7868 if (BI + 1 == BE) {
7869 const Expr *FinalExpr = dyn_cast<Expr>(*BI);
7870 if (!FinalExpr) {
7871 Info.FFDiag((*BI)->getBeginLoc(),
7872 diag::note_constexpr_stmt_expr_unsupported);
7873 return false;
7874 }
7875 return this->Visit(FinalExpr) && Scope.destroy();
7876 }
7877
7878 APValue ReturnValue;
7879 StmtResult Result = { ReturnValue, nullptr };
7880 EvalStmtResult ESR = EvaluateStmt(Result, Info, *BI);
7881 if (ESR != ESR_Succeeded) {
7882 // FIXME: If the statement-expression terminated due to 'return',
7883 // 'break', or 'continue', it would be nice to propagate that to
7884 // the outer statement evaluation rather than bailing out.
7885 if (ESR != ESR_Failed)
7886 Info.FFDiag((*BI)->getBeginLoc(),
7887 diag::note_constexpr_stmt_expr_unsupported);
7888 return false;
7889 }
7890 }
7891
7892 llvm_unreachable("Return from function from the loop above.");
7893 }
7894
7895 /// Visit a value which is evaluated, but whose value is ignored.
VisitIgnoredValue(const Expr * E)7896 void VisitIgnoredValue(const Expr *E) {
7897 EvaluateIgnoredValue(Info, E);
7898 }
7899
7900 /// Potentially visit a MemberExpr's base expression.
VisitIgnoredBaseExpression(const Expr * E)7901 void VisitIgnoredBaseExpression(const Expr *E) {
7902 // While MSVC doesn't evaluate the base expression, it does diagnose the
7903 // presence of side-effecting behavior.
7904 if (Info.getLangOpts().MSVCCompat && !E->HasSideEffects(Info.Ctx))
7905 return;
7906 VisitIgnoredValue(E);
7907 }
7908 };
7909
7910 } // namespace
7911
7912 //===----------------------------------------------------------------------===//
7913 // Common base class for lvalue and temporary evaluation.
7914 //===----------------------------------------------------------------------===//
7915 namespace {
7916 template<class Derived>
7917 class LValueExprEvaluatorBase
7918 : public ExprEvaluatorBase<Derived> {
7919 protected:
7920 LValue &Result;
7921 bool InvalidBaseOK;
7922 typedef LValueExprEvaluatorBase LValueExprEvaluatorBaseTy;
7923 typedef ExprEvaluatorBase<Derived> ExprEvaluatorBaseTy;
7924
Success(APValue::LValueBase B)7925 bool Success(APValue::LValueBase B) {
7926 Result.set(B);
7927 return true;
7928 }
7929
evaluatePointer(const Expr * E,LValue & Result)7930 bool evaluatePointer(const Expr *E, LValue &Result) {
7931 return EvaluatePointer(E, Result, this->Info, InvalidBaseOK);
7932 }
7933
7934 public:
LValueExprEvaluatorBase(EvalInfo & Info,LValue & Result,bool InvalidBaseOK)7935 LValueExprEvaluatorBase(EvalInfo &Info, LValue &Result, bool InvalidBaseOK)
7936 : ExprEvaluatorBaseTy(Info), Result(Result),
7937 InvalidBaseOK(InvalidBaseOK) {}
7938
Success(const APValue & V,const Expr * E)7939 bool Success(const APValue &V, const Expr *E) {
7940 Result.setFrom(this->Info.Ctx, V);
7941 return true;
7942 }
7943
VisitMemberExpr(const MemberExpr * E)7944 bool VisitMemberExpr(const MemberExpr *E) {
7945 // Handle non-static data members.
7946 QualType BaseTy;
7947 bool EvalOK;
7948 if (E->isArrow()) {
7949 EvalOK = evaluatePointer(E->getBase(), Result);
7950 BaseTy = E->getBase()->getType()->castAs<PointerType>()->getPointeeType();
7951 } else if (E->getBase()->isRValue()) {
7952 assert(E->getBase()->getType()->isRecordType());
7953 EvalOK = EvaluateTemporary(E->getBase(), Result, this->Info);
7954 BaseTy = E->getBase()->getType();
7955 } else {
7956 EvalOK = this->Visit(E->getBase());
7957 BaseTy = E->getBase()->getType();
7958 }
7959 if (!EvalOK) {
7960 if (!InvalidBaseOK)
7961 return false;
7962 Result.setInvalid(E);
7963 return true;
7964 }
7965
7966 const ValueDecl *MD = E->getMemberDecl();
7967 if (const FieldDecl *FD = dyn_cast<FieldDecl>(E->getMemberDecl())) {
7968 assert(BaseTy->castAs<RecordType>()->getDecl()->getCanonicalDecl() ==
7969 FD->getParent()->getCanonicalDecl() && "record / field mismatch");
7970 (void)BaseTy;
7971 if (!HandleLValueMember(this->Info, E, Result, FD))
7972 return false;
7973 } else if (const IndirectFieldDecl *IFD = dyn_cast<IndirectFieldDecl>(MD)) {
7974 if (!HandleLValueIndirectMember(this->Info, E, Result, IFD))
7975 return false;
7976 } else
7977 return this->Error(E);
7978
7979 if (MD->getType()->isReferenceType()) {
7980 APValue RefValue;
7981 if (!handleLValueToRValueConversion(this->Info, E, MD->getType(), Result,
7982 RefValue))
7983 return false;
7984 return Success(RefValue, E);
7985 }
7986 return true;
7987 }
7988
VisitBinaryOperator(const BinaryOperator * E)7989 bool VisitBinaryOperator(const BinaryOperator *E) {
7990 switch (E->getOpcode()) {
7991 default:
7992 return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
7993
7994 case BO_PtrMemD:
7995 case BO_PtrMemI:
7996 return HandleMemberPointerAccess(this->Info, E, Result);
7997 }
7998 }
7999
VisitCastExpr(const CastExpr * E)8000 bool VisitCastExpr(const CastExpr *E) {
8001 switch (E->getCastKind()) {
8002 default:
8003 return ExprEvaluatorBaseTy::VisitCastExpr(E);
8004
8005 case CK_DerivedToBase:
8006 case CK_UncheckedDerivedToBase:
8007 if (!this->Visit(E->getSubExpr()))
8008 return false;
8009
8010 // Now figure out the necessary offset to add to the base LV to get from
8011 // the derived class to the base class.
8012 return HandleLValueBasePath(this->Info, E, E->getSubExpr()->getType(),
8013 Result);
8014 }
8015 }
8016 };
8017 }
8018
8019 //===----------------------------------------------------------------------===//
8020 // LValue Evaluation
8021 //
8022 // This is used for evaluating lvalues (in C and C++), xvalues (in C++11),
8023 // function designators (in C), decl references to void objects (in C), and
8024 // temporaries (if building with -Wno-address-of-temporary).
8025 //
8026 // LValue evaluation produces values comprising a base expression of one of the
8027 // following types:
8028 // - Declarations
8029 // * VarDecl
8030 // * FunctionDecl
8031 // - Literals
8032 // * CompoundLiteralExpr in C (and in global scope in C++)
8033 // * StringLiteral
8034 // * PredefinedExpr
8035 // * ObjCStringLiteralExpr
8036 // * ObjCEncodeExpr
8037 // * AddrLabelExpr
8038 // * BlockExpr
8039 // * CallExpr for a MakeStringConstant builtin
8040 // - typeid(T) expressions, as TypeInfoLValues
8041 // - Locals and temporaries
8042 // * MaterializeTemporaryExpr
8043 // * Any Expr, with a CallIndex indicating the function in which the temporary
8044 // was evaluated, for cases where the MaterializeTemporaryExpr is missing
8045 // from the AST (FIXME).
8046 // * A MaterializeTemporaryExpr that has static storage duration, with no
8047 // CallIndex, for a lifetime-extended temporary.
8048 // * The ConstantExpr that is currently being evaluated during evaluation of an
8049 // immediate invocation.
8050 // plus an offset in bytes.
8051 //===----------------------------------------------------------------------===//
8052 namespace {
8053 class LValueExprEvaluator
8054 : public LValueExprEvaluatorBase<LValueExprEvaluator> {
8055 public:
LValueExprEvaluator(EvalInfo & Info,LValue & Result,bool InvalidBaseOK)8056 LValueExprEvaluator(EvalInfo &Info, LValue &Result, bool InvalidBaseOK) :
8057 LValueExprEvaluatorBaseTy(Info, Result, InvalidBaseOK) {}
8058
8059 bool VisitVarDecl(const Expr *E, const VarDecl *VD);
8060 bool VisitUnaryPreIncDec(const UnaryOperator *UO);
8061
8062 bool VisitDeclRefExpr(const DeclRefExpr *E);
VisitPredefinedExpr(const PredefinedExpr * E)8063 bool VisitPredefinedExpr(const PredefinedExpr *E) { return Success(E); }
8064 bool VisitMaterializeTemporaryExpr(const MaterializeTemporaryExpr *E);
8065 bool VisitCompoundLiteralExpr(const CompoundLiteralExpr *E);
8066 bool VisitMemberExpr(const MemberExpr *E);
VisitStringLiteral(const StringLiteral * E)8067 bool VisitStringLiteral(const StringLiteral *E) { return Success(E); }
VisitObjCEncodeExpr(const ObjCEncodeExpr * E)8068 bool VisitObjCEncodeExpr(const ObjCEncodeExpr *E) { return Success(E); }
8069 bool VisitCXXTypeidExpr(const CXXTypeidExpr *E);
8070 bool VisitCXXUuidofExpr(const CXXUuidofExpr *E);
8071 bool VisitArraySubscriptExpr(const ArraySubscriptExpr *E);
8072 bool VisitUnaryDeref(const UnaryOperator *E);
8073 bool VisitUnaryReal(const UnaryOperator *E);
8074 bool VisitUnaryImag(const UnaryOperator *E);
VisitUnaryPreInc(const UnaryOperator * UO)8075 bool VisitUnaryPreInc(const UnaryOperator *UO) {
8076 return VisitUnaryPreIncDec(UO);
8077 }
VisitUnaryPreDec(const UnaryOperator * UO)8078 bool VisitUnaryPreDec(const UnaryOperator *UO) {
8079 return VisitUnaryPreIncDec(UO);
8080 }
8081 bool VisitBinAssign(const BinaryOperator *BO);
8082 bool VisitCompoundAssignOperator(const CompoundAssignOperator *CAO);
8083
VisitCastExpr(const CastExpr * E)8084 bool VisitCastExpr(const CastExpr *E) {
8085 switch (E->getCastKind()) {
8086 default:
8087 return LValueExprEvaluatorBaseTy::VisitCastExpr(E);
8088
8089 case CK_LValueBitCast:
8090 this->CCEDiag(E, diag::note_constexpr_invalid_cast) << 2;
8091 if (!Visit(E->getSubExpr()))
8092 return false;
8093 Result.Designator.setInvalid();
8094 return true;
8095
8096 case CK_BaseToDerived:
8097 if (!Visit(E->getSubExpr()))
8098 return false;
8099 return HandleBaseToDerivedCast(Info, E, Result);
8100
8101 case CK_Dynamic:
8102 if (!Visit(E->getSubExpr()))
8103 return false;
8104 return HandleDynamicCast(Info, cast<ExplicitCastExpr>(E), Result);
8105 }
8106 }
8107 };
8108 } // end anonymous namespace
8109
8110 /// Evaluate an expression as an lvalue. This can be legitimately called on
8111 /// expressions which are not glvalues, in three cases:
8112 /// * function designators in C, and
8113 /// * "extern void" objects
8114 /// * @selector() expressions in Objective-C
EvaluateLValue(const Expr * E,LValue & Result,EvalInfo & Info,bool InvalidBaseOK)8115 static bool EvaluateLValue(const Expr *E, LValue &Result, EvalInfo &Info,
8116 bool InvalidBaseOK) {
8117 assert(!E->isValueDependent());
8118 assert(E->isGLValue() || E->getType()->isFunctionType() ||
8119 E->getType()->isVoidType() || isa<ObjCSelectorExpr>(E));
8120 return LValueExprEvaluator(Info, Result, InvalidBaseOK).Visit(E);
8121 }
8122
VisitDeclRefExpr(const DeclRefExpr * E)8123 bool LValueExprEvaluator::VisitDeclRefExpr(const DeclRefExpr *E) {
8124 const NamedDecl *D = E->getDecl();
8125 if (isa<FunctionDecl, MSGuidDecl, TemplateParamObjectDecl>(D))
8126 return Success(cast<ValueDecl>(D));
8127 if (const VarDecl *VD = dyn_cast<VarDecl>(D))
8128 return VisitVarDecl(E, VD);
8129 if (const BindingDecl *BD = dyn_cast<BindingDecl>(D))
8130 return Visit(BD->getBinding());
8131 return Error(E);
8132 }
8133
8134
VisitVarDecl(const Expr * E,const VarDecl * VD)8135 bool LValueExprEvaluator::VisitVarDecl(const Expr *E, const VarDecl *VD) {
8136
8137 // If we are within a lambda's call operator, check whether the 'VD' referred
8138 // to within 'E' actually represents a lambda-capture that maps to a
8139 // data-member/field within the closure object, and if so, evaluate to the
8140 // field or what the field refers to.
8141 if (Info.CurrentCall && isLambdaCallOperator(Info.CurrentCall->Callee) &&
8142 isa<DeclRefExpr>(E) &&
8143 cast<DeclRefExpr>(E)->refersToEnclosingVariableOrCapture()) {
8144 // We don't always have a complete capture-map when checking or inferring if
8145 // the function call operator meets the requirements of a constexpr function
8146 // - but we don't need to evaluate the captures to determine constexprness
8147 // (dcl.constexpr C++17).
8148 if (Info.checkingPotentialConstantExpression())
8149 return false;
8150
8151 if (auto *FD = Info.CurrentCall->LambdaCaptureFields.lookup(VD)) {
8152 // Start with 'Result' referring to the complete closure object...
8153 Result = *Info.CurrentCall->This;
8154 // ... then update it to refer to the field of the closure object
8155 // that represents the capture.
8156 if (!HandleLValueMember(Info, E, Result, FD))
8157 return false;
8158 // And if the field is of reference type, update 'Result' to refer to what
8159 // the field refers to.
8160 if (FD->getType()->isReferenceType()) {
8161 APValue RVal;
8162 if (!handleLValueToRValueConversion(Info, E, FD->getType(), Result,
8163 RVal))
8164 return false;
8165 Result.setFrom(Info.Ctx, RVal);
8166 }
8167 return true;
8168 }
8169 }
8170
8171 CallStackFrame *Frame = nullptr;
8172 unsigned Version = 0;
8173 if (VD->hasLocalStorage()) {
8174 // Only if a local variable was declared in the function currently being
8175 // evaluated, do we expect to be able to find its value in the current
8176 // frame. (Otherwise it was likely declared in an enclosing context and
8177 // could either have a valid evaluatable value (for e.g. a constexpr
8178 // variable) or be ill-formed (and trigger an appropriate evaluation
8179 // diagnostic)).
8180 CallStackFrame *CurrFrame = Info.CurrentCall;
8181 if (CurrFrame->Callee && CurrFrame->Callee->Equals(VD->getDeclContext())) {
8182 // Function parameters are stored in some caller's frame. (Usually the
8183 // immediate caller, but for an inherited constructor they may be more
8184 // distant.)
8185 if (auto *PVD = dyn_cast<ParmVarDecl>(VD)) {
8186 if (CurrFrame->Arguments) {
8187 VD = CurrFrame->Arguments.getOrigParam(PVD);
8188 Frame =
8189 Info.getCallFrameAndDepth(CurrFrame->Arguments.CallIndex).first;
8190 Version = CurrFrame->Arguments.Version;
8191 }
8192 } else {
8193 Frame = CurrFrame;
8194 Version = CurrFrame->getCurrentTemporaryVersion(VD);
8195 }
8196 }
8197 }
8198
8199 if (!VD->getType()->isReferenceType()) {
8200 if (Frame) {
8201 Result.set({VD, Frame->Index, Version});
8202 return true;
8203 }
8204 return Success(VD);
8205 }
8206
8207 if (!Info.getLangOpts().CPlusPlus11) {
8208 Info.CCEDiag(E, diag::note_constexpr_ltor_non_integral, 1)
8209 << VD << VD->getType();
8210 Info.Note(VD->getLocation(), diag::note_declared_at);
8211 }
8212
8213 APValue *V;
8214 if (!evaluateVarDeclInit(Info, E, VD, Frame, Version, V))
8215 return false;
8216 if (!V->hasValue()) {
8217 // FIXME: Is it possible for V to be indeterminate here? If so, we should
8218 // adjust the diagnostic to say that.
8219 if (!Info.checkingPotentialConstantExpression())
8220 Info.FFDiag(E, diag::note_constexpr_use_uninit_reference);
8221 return false;
8222 }
8223 return Success(*V, E);
8224 }
8225
VisitMaterializeTemporaryExpr(const MaterializeTemporaryExpr * E)8226 bool LValueExprEvaluator::VisitMaterializeTemporaryExpr(
8227 const MaterializeTemporaryExpr *E) {
8228 // Walk through the expression to find the materialized temporary itself.
8229 SmallVector<const Expr *, 2> CommaLHSs;
8230 SmallVector<SubobjectAdjustment, 2> Adjustments;
8231 const Expr *Inner =
8232 E->getSubExpr()->skipRValueSubobjectAdjustments(CommaLHSs, Adjustments);
8233
8234 // If we passed any comma operators, evaluate their LHSs.
8235 for (unsigned I = 0, N = CommaLHSs.size(); I != N; ++I)
8236 if (!EvaluateIgnoredValue(Info, CommaLHSs[I]))
8237 return false;
8238
8239 // A materialized temporary with static storage duration can appear within the
8240 // result of a constant expression evaluation, so we need to preserve its
8241 // value for use outside this evaluation.
8242 APValue *Value;
8243 if (E->getStorageDuration() == SD_Static) {
8244 // FIXME: What about SD_Thread?
8245 Value = E->getOrCreateValue(true);
8246 *Value = APValue();
8247 Result.set(E);
8248 } else {
8249 Value = &Info.CurrentCall->createTemporary(
8250 E, E->getType(),
8251 E->getStorageDuration() == SD_FullExpression ? ScopeKind::FullExpression
8252 : ScopeKind::Block,
8253 Result);
8254 }
8255
8256 QualType Type = Inner->getType();
8257
8258 // Materialize the temporary itself.
8259 if (!EvaluateInPlace(*Value, Info, Result, Inner)) {
8260 *Value = APValue();
8261 return false;
8262 }
8263
8264 // Adjust our lvalue to refer to the desired subobject.
8265 for (unsigned I = Adjustments.size(); I != 0; /**/) {
8266 --I;
8267 switch (Adjustments[I].Kind) {
8268 case SubobjectAdjustment::DerivedToBaseAdjustment:
8269 if (!HandleLValueBasePath(Info, Adjustments[I].DerivedToBase.BasePath,
8270 Type, Result))
8271 return false;
8272 Type = Adjustments[I].DerivedToBase.BasePath->getType();
8273 break;
8274
8275 case SubobjectAdjustment::FieldAdjustment:
8276 if (!HandleLValueMember(Info, E, Result, Adjustments[I].Field))
8277 return false;
8278 Type = Adjustments[I].Field->getType();
8279 break;
8280
8281 case SubobjectAdjustment::MemberPointerAdjustment:
8282 if (!HandleMemberPointerAccess(this->Info, Type, Result,
8283 Adjustments[I].Ptr.RHS))
8284 return false;
8285 Type = Adjustments[I].Ptr.MPT->getPointeeType();
8286 break;
8287 }
8288 }
8289
8290 return true;
8291 }
8292
8293 bool
VisitCompoundLiteralExpr(const CompoundLiteralExpr * E)8294 LValueExprEvaluator::VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) {
8295 assert((!Info.getLangOpts().CPlusPlus || E->isFileScope()) &&
8296 "lvalue compound literal in c++?");
8297 // Defer visiting the literal until the lvalue-to-rvalue conversion. We can
8298 // only see this when folding in C, so there's no standard to follow here.
8299 return Success(E);
8300 }
8301
VisitCXXTypeidExpr(const CXXTypeidExpr * E)8302 bool LValueExprEvaluator::VisitCXXTypeidExpr(const CXXTypeidExpr *E) {
8303 TypeInfoLValue TypeInfo;
8304
8305 if (!E->isPotentiallyEvaluated()) {
8306 if (E->isTypeOperand())
8307 TypeInfo = TypeInfoLValue(E->getTypeOperand(Info.Ctx).getTypePtr());
8308 else
8309 TypeInfo = TypeInfoLValue(E->getExprOperand()->getType().getTypePtr());
8310 } else {
8311 if (!Info.Ctx.getLangOpts().CPlusPlus20) {
8312 Info.CCEDiag(E, diag::note_constexpr_typeid_polymorphic)
8313 << E->getExprOperand()->getType()
8314 << E->getExprOperand()->getSourceRange();
8315 }
8316
8317 if (!Visit(E->getExprOperand()))
8318 return false;
8319
8320 Optional<DynamicType> DynType =
8321 ComputeDynamicType(Info, E, Result, AK_TypeId);
8322 if (!DynType)
8323 return false;
8324
8325 TypeInfo =
8326 TypeInfoLValue(Info.Ctx.getRecordType(DynType->Type).getTypePtr());
8327 }
8328
8329 return Success(APValue::LValueBase::getTypeInfo(TypeInfo, E->getType()));
8330 }
8331
VisitCXXUuidofExpr(const CXXUuidofExpr * E)8332 bool LValueExprEvaluator::VisitCXXUuidofExpr(const CXXUuidofExpr *E) {
8333 return Success(E->getGuidDecl());
8334 }
8335
VisitMemberExpr(const MemberExpr * E)8336 bool LValueExprEvaluator::VisitMemberExpr(const MemberExpr *E) {
8337 // Handle static data members.
8338 if (const VarDecl *VD = dyn_cast<VarDecl>(E->getMemberDecl())) {
8339 VisitIgnoredBaseExpression(E->getBase());
8340 return VisitVarDecl(E, VD);
8341 }
8342
8343 // Handle static member functions.
8344 if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(E->getMemberDecl())) {
8345 if (MD->isStatic()) {
8346 VisitIgnoredBaseExpression(E->getBase());
8347 return Success(MD);
8348 }
8349 }
8350
8351 // Handle non-static data members.
8352 return LValueExprEvaluatorBaseTy::VisitMemberExpr(E);
8353 }
8354
VisitArraySubscriptExpr(const ArraySubscriptExpr * E)8355 bool LValueExprEvaluator::VisitArraySubscriptExpr(const ArraySubscriptExpr *E) {
8356 // FIXME: Deal with vectors as array subscript bases.
8357 if (E->getBase()->getType()->isVectorType())
8358 return Error(E);
8359
8360 APSInt Index;
8361 bool Success = true;
8362
8363 // C++17's rules require us to evaluate the LHS first, regardless of which
8364 // side is the base.
8365 for (const Expr *SubExpr : {E->getLHS(), E->getRHS()}) {
8366 if (SubExpr == E->getBase() ? !evaluatePointer(SubExpr, Result)
8367 : !EvaluateInteger(SubExpr, Index, Info)) {
8368 if (!Info.noteFailure())
8369 return false;
8370 Success = false;
8371 }
8372 }
8373
8374 return Success &&
8375 HandleLValueArrayAdjustment(Info, E, Result, E->getType(), Index);
8376 }
8377
VisitUnaryDeref(const UnaryOperator * E)8378 bool LValueExprEvaluator::VisitUnaryDeref(const UnaryOperator *E) {
8379 return evaluatePointer(E->getSubExpr(), Result);
8380 }
8381
VisitUnaryReal(const UnaryOperator * E)8382 bool LValueExprEvaluator::VisitUnaryReal(const UnaryOperator *E) {
8383 if (!Visit(E->getSubExpr()))
8384 return false;
8385 // __real is a no-op on scalar lvalues.
8386 if (E->getSubExpr()->getType()->isAnyComplexType())
8387 HandleLValueComplexElement(Info, E, Result, E->getType(), false);
8388 return true;
8389 }
8390
VisitUnaryImag(const UnaryOperator * E)8391 bool LValueExprEvaluator::VisitUnaryImag(const UnaryOperator *E) {
8392 assert(E->getSubExpr()->getType()->isAnyComplexType() &&
8393 "lvalue __imag__ on scalar?");
8394 if (!Visit(E->getSubExpr()))
8395 return false;
8396 HandleLValueComplexElement(Info, E, Result, E->getType(), true);
8397 return true;
8398 }
8399
VisitUnaryPreIncDec(const UnaryOperator * UO)8400 bool LValueExprEvaluator::VisitUnaryPreIncDec(const UnaryOperator *UO) {
8401 if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure())
8402 return Error(UO);
8403
8404 if (!this->Visit(UO->getSubExpr()))
8405 return false;
8406
8407 return handleIncDec(
8408 this->Info, UO, Result, UO->getSubExpr()->getType(),
8409 UO->isIncrementOp(), nullptr);
8410 }
8411
VisitCompoundAssignOperator(const CompoundAssignOperator * CAO)8412 bool LValueExprEvaluator::VisitCompoundAssignOperator(
8413 const CompoundAssignOperator *CAO) {
8414 if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure())
8415 return Error(CAO);
8416
8417 bool Success = true;
8418
8419 // C++17 onwards require that we evaluate the RHS first.
8420 APValue RHS;
8421 if (!Evaluate(RHS, this->Info, CAO->getRHS())) {
8422 if (!Info.noteFailure())
8423 return false;
8424 Success = false;
8425 }
8426
8427 // The overall lvalue result is the result of evaluating the LHS.
8428 if (!this->Visit(CAO->getLHS()) || !Success)
8429 return false;
8430
8431 return handleCompoundAssignment(
8432 this->Info, CAO,
8433 Result, CAO->getLHS()->getType(), CAO->getComputationLHSType(),
8434 CAO->getOpForCompoundAssignment(CAO->getOpcode()), RHS);
8435 }
8436
VisitBinAssign(const BinaryOperator * E)8437 bool LValueExprEvaluator::VisitBinAssign(const BinaryOperator *E) {
8438 if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure())
8439 return Error(E);
8440
8441 bool Success = true;
8442
8443 // C++17 onwards require that we evaluate the RHS first.
8444 APValue NewVal;
8445 if (!Evaluate(NewVal, this->Info, E->getRHS())) {
8446 if (!Info.noteFailure())
8447 return false;
8448 Success = false;
8449 }
8450
8451 if (!this->Visit(E->getLHS()) || !Success)
8452 return false;
8453
8454 if (Info.getLangOpts().CPlusPlus20 &&
8455 !HandleUnionActiveMemberChange(Info, E->getLHS(), Result))
8456 return false;
8457
8458 return handleAssignment(this->Info, E, Result, E->getLHS()->getType(),
8459 NewVal);
8460 }
8461
8462 //===----------------------------------------------------------------------===//
8463 // Pointer Evaluation
8464 //===----------------------------------------------------------------------===//
8465
8466 /// Attempts to compute the number of bytes available at the pointer
8467 /// returned by a function with the alloc_size attribute. Returns true if we
8468 /// were successful. Places an unsigned number into `Result`.
8469 ///
8470 /// This expects the given CallExpr to be a call to a function with an
8471 /// alloc_size attribute.
getBytesReturnedByAllocSizeCall(const ASTContext & Ctx,const CallExpr * Call,llvm::APInt & Result)8472 static bool getBytesReturnedByAllocSizeCall(const ASTContext &Ctx,
8473 const CallExpr *Call,
8474 llvm::APInt &Result) {
8475 const AllocSizeAttr *AllocSize = getAllocSizeAttr(Call);
8476
8477 assert(AllocSize && AllocSize->getElemSizeParam().isValid());
8478 unsigned SizeArgNo = AllocSize->getElemSizeParam().getASTIndex();
8479 unsigned BitsInSizeT = Ctx.getTypeSize(Ctx.getSizeType());
8480 if (Call->getNumArgs() <= SizeArgNo)
8481 return false;
8482
8483 auto EvaluateAsSizeT = [&](const Expr *E, APSInt &Into) {
8484 Expr::EvalResult ExprResult;
8485 if (!E->EvaluateAsInt(ExprResult, Ctx, Expr::SE_AllowSideEffects))
8486 return false;
8487 Into = ExprResult.Val.getInt();
8488 if (Into.isNegative() || !Into.isIntN(BitsInSizeT))
8489 return false;
8490 Into = Into.zextOrSelf(BitsInSizeT);
8491 return true;
8492 };
8493
8494 APSInt SizeOfElem;
8495 if (!EvaluateAsSizeT(Call->getArg(SizeArgNo), SizeOfElem))
8496 return false;
8497
8498 if (!AllocSize->getNumElemsParam().isValid()) {
8499 Result = std::move(SizeOfElem);
8500 return true;
8501 }
8502
8503 APSInt NumberOfElems;
8504 unsigned NumArgNo = AllocSize->getNumElemsParam().getASTIndex();
8505 if (!EvaluateAsSizeT(Call->getArg(NumArgNo), NumberOfElems))
8506 return false;
8507
8508 bool Overflow;
8509 llvm::APInt BytesAvailable = SizeOfElem.umul_ov(NumberOfElems, Overflow);
8510 if (Overflow)
8511 return false;
8512
8513 Result = std::move(BytesAvailable);
8514 return true;
8515 }
8516
8517 /// Convenience function. LVal's base must be a call to an alloc_size
8518 /// function.
getBytesReturnedByAllocSizeCall(const ASTContext & Ctx,const LValue & LVal,llvm::APInt & Result)8519 static bool getBytesReturnedByAllocSizeCall(const ASTContext &Ctx,
8520 const LValue &LVal,
8521 llvm::APInt &Result) {
8522 assert(isBaseAnAllocSizeCall(LVal.getLValueBase()) &&
8523 "Can't get the size of a non alloc_size function");
8524 const auto *Base = LVal.getLValueBase().get<const Expr *>();
8525 const CallExpr *CE = tryUnwrapAllocSizeCall(Base);
8526 return getBytesReturnedByAllocSizeCall(Ctx, CE, Result);
8527 }
8528
8529 /// Attempts to evaluate the given LValueBase as the result of a call to
8530 /// a function with the alloc_size attribute. If it was possible to do so, this
8531 /// function will return true, make Result's Base point to said function call,
8532 /// and mark Result's Base as invalid.
evaluateLValueAsAllocSize(EvalInfo & Info,APValue::LValueBase Base,LValue & Result)8533 static bool evaluateLValueAsAllocSize(EvalInfo &Info, APValue::LValueBase Base,
8534 LValue &Result) {
8535 if (Base.isNull())
8536 return false;
8537
8538 // Because we do no form of static analysis, we only support const variables.
8539 //
8540 // Additionally, we can't support parameters, nor can we support static
8541 // variables (in the latter case, use-before-assign isn't UB; in the former,
8542 // we have no clue what they'll be assigned to).
8543 const auto *VD =
8544 dyn_cast_or_null<VarDecl>(Base.dyn_cast<const ValueDecl *>());
8545 if (!VD || !VD->isLocalVarDecl() || !VD->getType().isConstQualified())
8546 return false;
8547
8548 const Expr *Init = VD->getAnyInitializer();
8549 if (!Init)
8550 return false;
8551
8552 const Expr *E = Init->IgnoreParens();
8553 if (!tryUnwrapAllocSizeCall(E))
8554 return false;
8555
8556 // Store E instead of E unwrapped so that the type of the LValue's base is
8557 // what the user wanted.
8558 Result.setInvalid(E);
8559
8560 QualType Pointee = E->getType()->castAs<PointerType>()->getPointeeType();
8561 Result.addUnsizedArray(Info, E, Pointee);
8562 return true;
8563 }
8564
8565 namespace {
8566 class PointerExprEvaluator
8567 : public ExprEvaluatorBase<PointerExprEvaluator> {
8568 LValue &Result;
8569 bool InvalidBaseOK;
8570
Success(const Expr * E)8571 bool Success(const Expr *E) {
8572 Result.set(E);
8573 return true;
8574 }
8575
evaluateLValue(const Expr * E,LValue & Result)8576 bool evaluateLValue(const Expr *E, LValue &Result) {
8577 return EvaluateLValue(E, Result, Info, InvalidBaseOK);
8578 }
8579
evaluatePointer(const Expr * E,LValue & Result)8580 bool evaluatePointer(const Expr *E, LValue &Result) {
8581 return EvaluatePointer(E, Result, Info, InvalidBaseOK);
8582 }
8583
8584 bool visitNonBuiltinCallExpr(const CallExpr *E);
8585 public:
8586
PointerExprEvaluator(EvalInfo & info,LValue & Result,bool InvalidBaseOK)8587 PointerExprEvaluator(EvalInfo &info, LValue &Result, bool InvalidBaseOK)
8588 : ExprEvaluatorBaseTy(info), Result(Result),
8589 InvalidBaseOK(InvalidBaseOK) {}
8590
Success(const APValue & V,const Expr * E)8591 bool Success(const APValue &V, const Expr *E) {
8592 Result.setFrom(Info.Ctx, V);
8593 return true;
8594 }
ZeroInitialization(const Expr * E)8595 bool ZeroInitialization(const Expr *E) {
8596 Result.setNull(Info.Ctx, E->getType());
8597 return true;
8598 }
8599
8600 bool VisitBinaryOperator(const BinaryOperator *E);
8601 bool VisitCastExpr(const CastExpr* E);
8602 bool VisitUnaryAddrOf(const UnaryOperator *E);
VisitObjCStringLiteral(const ObjCStringLiteral * E)8603 bool VisitObjCStringLiteral(const ObjCStringLiteral *E)
8604 { return Success(E); }
VisitObjCBoxedExpr(const ObjCBoxedExpr * E)8605 bool VisitObjCBoxedExpr(const ObjCBoxedExpr *E) {
8606 if (E->isExpressibleAsConstantInitializer())
8607 return Success(E);
8608 if (Info.noteFailure())
8609 EvaluateIgnoredValue(Info, E->getSubExpr());
8610 return Error(E);
8611 }
VisitAddrLabelExpr(const AddrLabelExpr * E)8612 bool VisitAddrLabelExpr(const AddrLabelExpr *E)
8613 { return Success(E); }
8614 bool VisitCallExpr(const CallExpr *E);
8615 bool VisitBuiltinCallExpr(const CallExpr *E, unsigned BuiltinOp);
VisitBlockExpr(const BlockExpr * E)8616 bool VisitBlockExpr(const BlockExpr *E) {
8617 if (!E->getBlockDecl()->hasCaptures())
8618 return Success(E);
8619 return Error(E);
8620 }
VisitCXXThisExpr(const CXXThisExpr * E)8621 bool VisitCXXThisExpr(const CXXThisExpr *E) {
8622 // Can't look at 'this' when checking a potential constant expression.
8623 if (Info.checkingPotentialConstantExpression())
8624 return false;
8625 if (!Info.CurrentCall->This) {
8626 if (Info.getLangOpts().CPlusPlus11)
8627 Info.FFDiag(E, diag::note_constexpr_this) << E->isImplicit();
8628 else
8629 Info.FFDiag(E);
8630 return false;
8631 }
8632 Result = *Info.CurrentCall->This;
8633 // If we are inside a lambda's call operator, the 'this' expression refers
8634 // to the enclosing '*this' object (either by value or reference) which is
8635 // either copied into the closure object's field that represents the '*this'
8636 // or refers to '*this'.
8637 if (isLambdaCallOperator(Info.CurrentCall->Callee)) {
8638 // Ensure we actually have captured 'this'. (an error will have
8639 // been previously reported if not).
8640 if (!Info.CurrentCall->LambdaThisCaptureField)
8641 return false;
8642
8643 // Update 'Result' to refer to the data member/field of the closure object
8644 // that represents the '*this' capture.
8645 if (!HandleLValueMember(Info, E, Result,
8646 Info.CurrentCall->LambdaThisCaptureField))
8647 return false;
8648 // If we captured '*this' by reference, replace the field with its referent.
8649 if (Info.CurrentCall->LambdaThisCaptureField->getType()
8650 ->isPointerType()) {
8651 APValue RVal;
8652 if (!handleLValueToRValueConversion(Info, E, E->getType(), Result,
8653 RVal))
8654 return false;
8655
8656 Result.setFrom(Info.Ctx, RVal);
8657 }
8658 }
8659 return true;
8660 }
8661
8662 bool VisitCXXNewExpr(const CXXNewExpr *E);
8663
VisitSourceLocExpr(const SourceLocExpr * E)8664 bool VisitSourceLocExpr(const SourceLocExpr *E) {
8665 assert(E->isStringType() && "SourceLocExpr isn't a pointer type?");
8666 APValue LValResult = E->EvaluateInContext(
8667 Info.Ctx, Info.CurrentCall->CurSourceLocExprScope.getDefaultExpr());
8668 Result.setFrom(Info.Ctx, LValResult);
8669 return true;
8670 }
8671
8672 // FIXME: Missing: @protocol, @selector
8673 };
8674 } // end anonymous namespace
8675
EvaluatePointer(const Expr * E,LValue & Result,EvalInfo & Info,bool InvalidBaseOK)8676 static bool EvaluatePointer(const Expr* E, LValue& Result, EvalInfo &Info,
8677 bool InvalidBaseOK) {
8678 assert(!E->isValueDependent());
8679 assert(E->isRValue() && E->getType()->hasPointerRepresentation());
8680 return PointerExprEvaluator(Info, Result, InvalidBaseOK).Visit(E);
8681 }
8682
VisitBinaryOperator(const BinaryOperator * E)8683 bool PointerExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
8684 if (E->getOpcode() != BO_Add &&
8685 E->getOpcode() != BO_Sub)
8686 return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
8687
8688 const Expr *PExp = E->getLHS();
8689 const Expr *IExp = E->getRHS();
8690 if (IExp->getType()->isPointerType())
8691 std::swap(PExp, IExp);
8692
8693 bool EvalPtrOK = evaluatePointer(PExp, Result);
8694 if (!EvalPtrOK && !Info.noteFailure())
8695 return false;
8696
8697 llvm::APSInt Offset;
8698 if (!EvaluateInteger(IExp, Offset, Info) || !EvalPtrOK)
8699 return false;
8700
8701 if (E->getOpcode() == BO_Sub)
8702 negateAsSigned(Offset);
8703
8704 QualType Pointee = PExp->getType()->castAs<PointerType>()->getPointeeType();
8705 return HandleLValueArrayAdjustment(Info, E, Result, Pointee, Offset);
8706 }
8707
VisitUnaryAddrOf(const UnaryOperator * E)8708 bool PointerExprEvaluator::VisitUnaryAddrOf(const UnaryOperator *E) {
8709 return evaluateLValue(E->getSubExpr(), Result);
8710 }
8711
VisitCastExpr(const CastExpr * E)8712 bool PointerExprEvaluator::VisitCastExpr(const CastExpr *E) {
8713 const Expr *SubExpr = E->getSubExpr();
8714
8715 switch (E->getCastKind()) {
8716 default:
8717 break;
8718 case CK_BitCast:
8719 case CK_CPointerToObjCPointerCast:
8720 case CK_BlockPointerToObjCPointerCast:
8721 case CK_AnyPointerToBlockPointerCast:
8722 case CK_AddressSpaceConversion:
8723 if (!Visit(SubExpr))
8724 return false;
8725 // Bitcasts to cv void* are static_casts, not reinterpret_casts, so are
8726 // permitted in constant expressions in C++11. Bitcasts from cv void* are
8727 // also static_casts, but we disallow them as a resolution to DR1312.
8728 if (!E->getType()->isVoidPointerType()) {
8729 if (!Result.InvalidBase && !Result.Designator.Invalid &&
8730 !Result.IsNullPtr &&
8731 Info.Ctx.hasSameUnqualifiedType(Result.Designator.getType(Info.Ctx),
8732 E->getType()->getPointeeType()) &&
8733 Info.getStdAllocatorCaller("allocate")) {
8734 // Inside a call to std::allocator::allocate and friends, we permit
8735 // casting from void* back to cv1 T* for a pointer that points to a
8736 // cv2 T.
8737 } else {
8738 Result.Designator.setInvalid();
8739 if (SubExpr->getType()->isVoidPointerType())
8740 CCEDiag(E, diag::note_constexpr_invalid_cast)
8741 << 3 << SubExpr->getType();
8742 else
8743 CCEDiag(E, diag::note_constexpr_invalid_cast) << 2;
8744 }
8745 }
8746 if (E->getCastKind() == CK_AddressSpaceConversion && Result.IsNullPtr)
8747 ZeroInitialization(E);
8748 return true;
8749
8750 case CK_DerivedToBase:
8751 case CK_UncheckedDerivedToBase:
8752 if (!evaluatePointer(E->getSubExpr(), Result))
8753 return false;
8754 if (!Result.Base && Result.Offset.isZero())
8755 return true;
8756
8757 // Now figure out the necessary offset to add to the base LV to get from
8758 // the derived class to the base class.
8759 return HandleLValueBasePath(Info, E, E->getSubExpr()->getType()->
8760 castAs<PointerType>()->getPointeeType(),
8761 Result);
8762
8763 case CK_BaseToDerived:
8764 if (!Visit(E->getSubExpr()))
8765 return false;
8766 if (!Result.Base && Result.Offset.isZero())
8767 return true;
8768 return HandleBaseToDerivedCast(Info, E, Result);
8769
8770 case CK_Dynamic:
8771 if (!Visit(E->getSubExpr()))
8772 return false;
8773 return HandleDynamicCast(Info, cast<ExplicitCastExpr>(E), Result);
8774
8775 case CK_NullToPointer:
8776 VisitIgnoredValue(E->getSubExpr());
8777 return ZeroInitialization(E);
8778
8779 case CK_IntegralToPointer: {
8780 CCEDiag(E, diag::note_constexpr_invalid_cast) << 2;
8781
8782 APValue Value;
8783 if (!EvaluateIntegerOrLValue(SubExpr, Value, Info))
8784 break;
8785
8786 if (Value.isInt()) {
8787 unsigned Size = Info.Ctx.getTypeSize(E->getType());
8788 uint64_t N = Value.getInt().extOrTrunc(Size).getZExtValue();
8789 Result.Base = (Expr*)nullptr;
8790 Result.InvalidBase = false;
8791 Result.Offset = CharUnits::fromQuantity(N);
8792 Result.Designator.setInvalid();
8793 Result.IsNullPtr = false;
8794 return true;
8795 } else {
8796 // Cast is of an lvalue, no need to change value.
8797 Result.setFrom(Info.Ctx, Value);
8798 return true;
8799 }
8800 }
8801
8802 case CK_ArrayToPointerDecay: {
8803 if (SubExpr->isGLValue()) {
8804 if (!evaluateLValue(SubExpr, Result))
8805 return false;
8806 } else {
8807 APValue &Value = Info.CurrentCall->createTemporary(
8808 SubExpr, SubExpr->getType(), ScopeKind::FullExpression, Result);
8809 if (!EvaluateInPlace(Value, Info, Result, SubExpr))
8810 return false;
8811 }
8812 // The result is a pointer to the first element of the array.
8813 auto *AT = Info.Ctx.getAsArrayType(SubExpr->getType());
8814 if (auto *CAT = dyn_cast<ConstantArrayType>(AT))
8815 Result.addArray(Info, E, CAT);
8816 else
8817 Result.addUnsizedArray(Info, E, AT->getElementType());
8818 return true;
8819 }
8820
8821 case CK_FunctionToPointerDecay:
8822 return evaluateLValue(SubExpr, Result);
8823
8824 case CK_LValueToRValue: {
8825 LValue LVal;
8826 if (!evaluateLValue(E->getSubExpr(), LVal))
8827 return false;
8828
8829 APValue RVal;
8830 // Note, we use the subexpression's type in order to retain cv-qualifiers.
8831 if (!handleLValueToRValueConversion(Info, E, E->getSubExpr()->getType(),
8832 LVal, RVal))
8833 return InvalidBaseOK &&
8834 evaluateLValueAsAllocSize(Info, LVal.Base, Result);
8835 return Success(RVal, E);
8836 }
8837 }
8838
8839 return ExprEvaluatorBaseTy::VisitCastExpr(E);
8840 }
8841
GetAlignOfType(EvalInfo & Info,QualType T,UnaryExprOrTypeTrait ExprKind)8842 static CharUnits GetAlignOfType(EvalInfo &Info, QualType T,
8843 UnaryExprOrTypeTrait ExprKind) {
8844 // C++ [expr.alignof]p3:
8845 // When alignof is applied to a reference type, the result is the
8846 // alignment of the referenced type.
8847 if (const ReferenceType *Ref = T->getAs<ReferenceType>())
8848 T = Ref->getPointeeType();
8849
8850 if (T.getQualifiers().hasUnaligned())
8851 return CharUnits::One();
8852
8853 const bool AlignOfReturnsPreferred =
8854 Info.Ctx.getLangOpts().getClangABICompat() <= LangOptions::ClangABI::Ver7;
8855
8856 // __alignof is defined to return the preferred alignment.
8857 // Before 8, clang returned the preferred alignment for alignof and _Alignof
8858 // as well.
8859 if (ExprKind == UETT_PreferredAlignOf || AlignOfReturnsPreferred)
8860 return Info.Ctx.toCharUnitsFromBits(
8861 Info.Ctx.getPreferredTypeAlign(T.getTypePtr()));
8862 // alignof and _Alignof are defined to return the ABI alignment.
8863 else if (ExprKind == UETT_AlignOf)
8864 return Info.Ctx.getTypeAlignInChars(T.getTypePtr());
8865 else
8866 llvm_unreachable("GetAlignOfType on a non-alignment ExprKind");
8867 }
8868
GetAlignOfExpr(EvalInfo & Info,const Expr * E,UnaryExprOrTypeTrait ExprKind)8869 static CharUnits GetAlignOfExpr(EvalInfo &Info, const Expr *E,
8870 UnaryExprOrTypeTrait ExprKind) {
8871 E = E->IgnoreParens();
8872
8873 // The kinds of expressions that we have special-case logic here for
8874 // should be kept up to date with the special checks for those
8875 // expressions in Sema.
8876
8877 // alignof decl is always accepted, even if it doesn't make sense: we default
8878 // to 1 in those cases.
8879 if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
8880 return Info.Ctx.getDeclAlign(DRE->getDecl(),
8881 /*RefAsPointee*/true);
8882
8883 if (const MemberExpr *ME = dyn_cast<MemberExpr>(E))
8884 return Info.Ctx.getDeclAlign(ME->getMemberDecl(),
8885 /*RefAsPointee*/true);
8886
8887 return GetAlignOfType(Info, E->getType(), ExprKind);
8888 }
8889
getBaseAlignment(EvalInfo & Info,const LValue & Value)8890 static CharUnits getBaseAlignment(EvalInfo &Info, const LValue &Value) {
8891 if (const auto *VD = Value.Base.dyn_cast<const ValueDecl *>())
8892 return Info.Ctx.getDeclAlign(VD);
8893 if (const auto *E = Value.Base.dyn_cast<const Expr *>())
8894 return GetAlignOfExpr(Info, E, UETT_AlignOf);
8895 return GetAlignOfType(Info, Value.Base.getTypeInfoType(), UETT_AlignOf);
8896 }
8897
8898 /// Evaluate the value of the alignment argument to __builtin_align_{up,down},
8899 /// __builtin_is_aligned and __builtin_assume_aligned.
getAlignmentArgument(const Expr * E,QualType ForType,EvalInfo & Info,APSInt & Alignment)8900 static bool getAlignmentArgument(const Expr *E, QualType ForType,
8901 EvalInfo &Info, APSInt &Alignment) {
8902 if (!EvaluateInteger(E, Alignment, Info))
8903 return false;
8904 if (Alignment < 0 || !Alignment.isPowerOf2()) {
8905 Info.FFDiag(E, diag::note_constexpr_invalid_alignment) << Alignment;
8906 return false;
8907 }
8908 unsigned SrcWidth = Info.Ctx.getIntWidth(ForType);
8909 APSInt MaxValue(APInt::getOneBitSet(SrcWidth, SrcWidth - 1));
8910 if (APSInt::compareValues(Alignment, MaxValue) > 0) {
8911 Info.FFDiag(E, diag::note_constexpr_alignment_too_big)
8912 << MaxValue << ForType << Alignment;
8913 return false;
8914 }
8915 // Ensure both alignment and source value have the same bit width so that we
8916 // don't assert when computing the resulting value.
8917 APSInt ExtAlignment =
8918 APSInt(Alignment.zextOrTrunc(SrcWidth), /*isUnsigned=*/true);
8919 assert(APSInt::compareValues(Alignment, ExtAlignment) == 0 &&
8920 "Alignment should not be changed by ext/trunc");
8921 Alignment = ExtAlignment;
8922 assert(Alignment.getBitWidth() == SrcWidth);
8923 return true;
8924 }
8925
8926 // To be clear: this happily visits unsupported builtins. Better name welcomed.
visitNonBuiltinCallExpr(const CallExpr * E)8927 bool PointerExprEvaluator::visitNonBuiltinCallExpr(const CallExpr *E) {
8928 if (ExprEvaluatorBaseTy::VisitCallExpr(E))
8929 return true;
8930
8931 if (!(InvalidBaseOK && getAllocSizeAttr(E)))
8932 return false;
8933
8934 Result.setInvalid(E);
8935 QualType PointeeTy = E->getType()->castAs<PointerType>()->getPointeeType();
8936 Result.addUnsizedArray(Info, E, PointeeTy);
8937 return true;
8938 }
8939
VisitCallExpr(const CallExpr * E)8940 bool PointerExprEvaluator::VisitCallExpr(const CallExpr *E) {
8941 if (IsStringLiteralCall(E))
8942 return Success(E);
8943
8944 if (unsigned BuiltinOp = E->getBuiltinCallee())
8945 return VisitBuiltinCallExpr(E, BuiltinOp);
8946
8947 return visitNonBuiltinCallExpr(E);
8948 }
8949
8950 // Determine if T is a character type for which we guarantee that
8951 // sizeof(T) == 1.
isOneByteCharacterType(QualType T)8952 static bool isOneByteCharacterType(QualType T) {
8953 return T->isCharType() || T->isChar8Type();
8954 }
8955
VisitBuiltinCallExpr(const CallExpr * E,unsigned BuiltinOp)8956 bool PointerExprEvaluator::VisitBuiltinCallExpr(const CallExpr *E,
8957 unsigned BuiltinOp) {
8958 switch (BuiltinOp) {
8959 case Builtin::BI__builtin_addressof:
8960 return evaluateLValue(E->getArg(0), Result);
8961 case Builtin::BI__builtin_assume_aligned: {
8962 // We need to be very careful here because: if the pointer does not have the
8963 // asserted alignment, then the behavior is undefined, and undefined
8964 // behavior is non-constant.
8965 if (!evaluatePointer(E->getArg(0), Result))
8966 return false;
8967
8968 LValue OffsetResult(Result);
8969 APSInt Alignment;
8970 if (!getAlignmentArgument(E->getArg(1), E->getArg(0)->getType(), Info,
8971 Alignment))
8972 return false;
8973 CharUnits Align = CharUnits::fromQuantity(Alignment.getZExtValue());
8974
8975 if (E->getNumArgs() > 2) {
8976 APSInt Offset;
8977 if (!EvaluateInteger(E->getArg(2), Offset, Info))
8978 return false;
8979
8980 int64_t AdditionalOffset = -Offset.getZExtValue();
8981 OffsetResult.Offset += CharUnits::fromQuantity(AdditionalOffset);
8982 }
8983
8984 // If there is a base object, then it must have the correct alignment.
8985 if (OffsetResult.Base) {
8986 CharUnits BaseAlignment = getBaseAlignment(Info, OffsetResult);
8987
8988 if (BaseAlignment < Align) {
8989 Result.Designator.setInvalid();
8990 // FIXME: Add support to Diagnostic for long / long long.
8991 CCEDiag(E->getArg(0),
8992 diag::note_constexpr_baa_insufficient_alignment) << 0
8993 << (unsigned)BaseAlignment.getQuantity()
8994 << (unsigned)Align.getQuantity();
8995 return false;
8996 }
8997 }
8998
8999 // The offset must also have the correct alignment.
9000 if (OffsetResult.Offset.alignTo(Align) != OffsetResult.Offset) {
9001 Result.Designator.setInvalid();
9002
9003 (OffsetResult.Base
9004 ? CCEDiag(E->getArg(0),
9005 diag::note_constexpr_baa_insufficient_alignment) << 1
9006 : CCEDiag(E->getArg(0),
9007 diag::note_constexpr_baa_value_insufficient_alignment))
9008 << (int)OffsetResult.Offset.getQuantity()
9009 << (unsigned)Align.getQuantity();
9010 return false;
9011 }
9012
9013 return true;
9014 }
9015 case Builtin::BI__builtin_align_up:
9016 case Builtin::BI__builtin_align_down: {
9017 if (!evaluatePointer(E->getArg(0), Result))
9018 return false;
9019 APSInt Alignment;
9020 if (!getAlignmentArgument(E->getArg(1), E->getArg(0)->getType(), Info,
9021 Alignment))
9022 return false;
9023 CharUnits BaseAlignment = getBaseAlignment(Info, Result);
9024 CharUnits PtrAlign = BaseAlignment.alignmentAtOffset(Result.Offset);
9025 // For align_up/align_down, we can return the same value if the alignment
9026 // is known to be greater or equal to the requested value.
9027 if (PtrAlign.getQuantity() >= Alignment)
9028 return true;
9029
9030 // The alignment could be greater than the minimum at run-time, so we cannot
9031 // infer much about the resulting pointer value. One case is possible:
9032 // For `_Alignas(32) char buf[N]; __builtin_align_down(&buf[idx], 32)` we
9033 // can infer the correct index if the requested alignment is smaller than
9034 // the base alignment so we can perform the computation on the offset.
9035 if (BaseAlignment.getQuantity() >= Alignment) {
9036 assert(Alignment.getBitWidth() <= 64 &&
9037 "Cannot handle > 64-bit address-space");
9038 uint64_t Alignment64 = Alignment.getZExtValue();
9039 CharUnits NewOffset = CharUnits::fromQuantity(
9040 BuiltinOp == Builtin::BI__builtin_align_down
9041 ? llvm::alignDown(Result.Offset.getQuantity(), Alignment64)
9042 : llvm::alignTo(Result.Offset.getQuantity(), Alignment64));
9043 Result.adjustOffset(NewOffset - Result.Offset);
9044 // TODO: diagnose out-of-bounds values/only allow for arrays?
9045 return true;
9046 }
9047 // Otherwise, we cannot constant-evaluate the result.
9048 Info.FFDiag(E->getArg(0), diag::note_constexpr_alignment_adjust)
9049 << Alignment;
9050 return false;
9051 }
9052 case Builtin::BI__builtin_operator_new:
9053 return HandleOperatorNewCall(Info, E, Result);
9054 case Builtin::BI__builtin_launder:
9055 return evaluatePointer(E->getArg(0), Result);
9056 case Builtin::BIstrchr:
9057 case Builtin::BIwcschr:
9058 case Builtin::BImemchr:
9059 case Builtin::BIwmemchr:
9060 if (Info.getLangOpts().CPlusPlus11)
9061 Info.CCEDiag(E, diag::note_constexpr_invalid_function)
9062 << /*isConstexpr*/0 << /*isConstructor*/0
9063 << (std::string("'") + Info.Ctx.BuiltinInfo.getName(BuiltinOp) + "'");
9064 else
9065 Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr);
9066 LLVM_FALLTHROUGH;
9067 case Builtin::BI__builtin_strchr:
9068 case Builtin::BI__builtin_wcschr:
9069 case Builtin::BI__builtin_memchr:
9070 case Builtin::BI__builtin_char_memchr:
9071 case Builtin::BI__builtin_wmemchr: {
9072 if (!Visit(E->getArg(0)))
9073 return false;
9074 APSInt Desired;
9075 if (!EvaluateInteger(E->getArg(1), Desired, Info))
9076 return false;
9077 uint64_t MaxLength = uint64_t(-1);
9078 if (BuiltinOp != Builtin::BIstrchr &&
9079 BuiltinOp != Builtin::BIwcschr &&
9080 BuiltinOp != Builtin::BI__builtin_strchr &&
9081 BuiltinOp != Builtin::BI__builtin_wcschr) {
9082 APSInt N;
9083 if (!EvaluateInteger(E->getArg(2), N, Info))
9084 return false;
9085 MaxLength = N.getExtValue();
9086 }
9087 // We cannot find the value if there are no candidates to match against.
9088 if (MaxLength == 0u)
9089 return ZeroInitialization(E);
9090 if (!Result.checkNullPointerForFoldAccess(Info, E, AK_Read) ||
9091 Result.Designator.Invalid)
9092 return false;
9093 QualType CharTy = Result.Designator.getType(Info.Ctx);
9094 bool IsRawByte = BuiltinOp == Builtin::BImemchr ||
9095 BuiltinOp == Builtin::BI__builtin_memchr;
9096 assert(IsRawByte ||
9097 Info.Ctx.hasSameUnqualifiedType(
9098 CharTy, E->getArg(0)->getType()->getPointeeType()));
9099 // Pointers to const void may point to objects of incomplete type.
9100 if (IsRawByte && CharTy->isIncompleteType()) {
9101 Info.FFDiag(E, diag::note_constexpr_ltor_incomplete_type) << CharTy;
9102 return false;
9103 }
9104 // Give up on byte-oriented matching against multibyte elements.
9105 // FIXME: We can compare the bytes in the correct order.
9106 if (IsRawByte && !isOneByteCharacterType(CharTy)) {
9107 Info.FFDiag(E, diag::note_constexpr_memchr_unsupported)
9108 << (std::string("'") + Info.Ctx.BuiltinInfo.getName(BuiltinOp) + "'")
9109 << CharTy;
9110 return false;
9111 }
9112 // Figure out what value we're actually looking for (after converting to
9113 // the corresponding unsigned type if necessary).
9114 uint64_t DesiredVal;
9115 bool StopAtNull = false;
9116 switch (BuiltinOp) {
9117 case Builtin::BIstrchr:
9118 case Builtin::BI__builtin_strchr:
9119 // strchr compares directly to the passed integer, and therefore
9120 // always fails if given an int that is not a char.
9121 if (!APSInt::isSameValue(HandleIntToIntCast(Info, E, CharTy,
9122 E->getArg(1)->getType(),
9123 Desired),
9124 Desired))
9125 return ZeroInitialization(E);
9126 StopAtNull = true;
9127 LLVM_FALLTHROUGH;
9128 case Builtin::BImemchr:
9129 case Builtin::BI__builtin_memchr:
9130 case Builtin::BI__builtin_char_memchr:
9131 // memchr compares by converting both sides to unsigned char. That's also
9132 // correct for strchr if we get this far (to cope with plain char being
9133 // unsigned in the strchr case).
9134 DesiredVal = Desired.trunc(Info.Ctx.getCharWidth()).getZExtValue();
9135 break;
9136
9137 case Builtin::BIwcschr:
9138 case Builtin::BI__builtin_wcschr:
9139 StopAtNull = true;
9140 LLVM_FALLTHROUGH;
9141 case Builtin::BIwmemchr:
9142 case Builtin::BI__builtin_wmemchr:
9143 // wcschr and wmemchr are given a wchar_t to look for. Just use it.
9144 DesiredVal = Desired.getZExtValue();
9145 break;
9146 }
9147
9148 for (; MaxLength; --MaxLength) {
9149 APValue Char;
9150 if (!handleLValueToRValueConversion(Info, E, CharTy, Result, Char) ||
9151 !Char.isInt())
9152 return false;
9153 if (Char.getInt().getZExtValue() == DesiredVal)
9154 return true;
9155 if (StopAtNull && !Char.getInt())
9156 break;
9157 if (!HandleLValueArrayAdjustment(Info, E, Result, CharTy, 1))
9158 return false;
9159 }
9160 // Not found: return nullptr.
9161 return ZeroInitialization(E);
9162 }
9163
9164 case Builtin::BImemcpy:
9165 case Builtin::BImemmove:
9166 case Builtin::BIwmemcpy:
9167 case Builtin::BIwmemmove:
9168 if (Info.getLangOpts().CPlusPlus11)
9169 Info.CCEDiag(E, diag::note_constexpr_invalid_function)
9170 << /*isConstexpr*/0 << /*isConstructor*/0
9171 << (std::string("'") + Info.Ctx.BuiltinInfo.getName(BuiltinOp) + "'");
9172 else
9173 Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr);
9174 LLVM_FALLTHROUGH;
9175 case Builtin::BI__builtin_memcpy:
9176 case Builtin::BI__builtin_memmove:
9177 case Builtin::BI__builtin_wmemcpy:
9178 case Builtin::BI__builtin_wmemmove: {
9179 bool WChar = BuiltinOp == Builtin::BIwmemcpy ||
9180 BuiltinOp == Builtin::BIwmemmove ||
9181 BuiltinOp == Builtin::BI__builtin_wmemcpy ||
9182 BuiltinOp == Builtin::BI__builtin_wmemmove;
9183 bool Move = BuiltinOp == Builtin::BImemmove ||
9184 BuiltinOp == Builtin::BIwmemmove ||
9185 BuiltinOp == Builtin::BI__builtin_memmove ||
9186 BuiltinOp == Builtin::BI__builtin_wmemmove;
9187
9188 // The result of mem* is the first argument.
9189 if (!Visit(E->getArg(0)))
9190 return false;
9191 LValue Dest = Result;
9192
9193 LValue Src;
9194 if (!EvaluatePointer(E->getArg(1), Src, Info))
9195 return false;
9196
9197 APSInt N;
9198 if (!EvaluateInteger(E->getArg(2), N, Info))
9199 return false;
9200 assert(!N.isSigned() && "memcpy and friends take an unsigned size");
9201
9202 // If the size is zero, we treat this as always being a valid no-op.
9203 // (Even if one of the src and dest pointers is null.)
9204 if (!N)
9205 return true;
9206
9207 // Otherwise, if either of the operands is null, we can't proceed. Don't
9208 // try to determine the type of the copied objects, because there aren't
9209 // any.
9210 if (!Src.Base || !Dest.Base) {
9211 APValue Val;
9212 (!Src.Base ? Src : Dest).moveInto(Val);
9213 Info.FFDiag(E, diag::note_constexpr_memcpy_null)
9214 << Move << WChar << !!Src.Base
9215 << Val.getAsString(Info.Ctx, E->getArg(0)->getType());
9216 return false;
9217 }
9218 if (Src.Designator.Invalid || Dest.Designator.Invalid)
9219 return false;
9220
9221 // We require that Src and Dest are both pointers to arrays of
9222 // trivially-copyable type. (For the wide version, the designator will be
9223 // invalid if the designated object is not a wchar_t.)
9224 QualType T = Dest.Designator.getType(Info.Ctx);
9225 QualType SrcT = Src.Designator.getType(Info.Ctx);
9226 if (!Info.Ctx.hasSameUnqualifiedType(T, SrcT)) {
9227 // FIXME: Consider using our bit_cast implementation to support this.
9228 Info.FFDiag(E, diag::note_constexpr_memcpy_type_pun) << Move << SrcT << T;
9229 return false;
9230 }
9231 if (T->isIncompleteType()) {
9232 Info.FFDiag(E, diag::note_constexpr_memcpy_incomplete_type) << Move << T;
9233 return false;
9234 }
9235 if (!T.isTriviallyCopyableType(Info.Ctx)) {
9236 Info.FFDiag(E, diag::note_constexpr_memcpy_nontrivial) << Move << T;
9237 return false;
9238 }
9239
9240 // Figure out how many T's we're copying.
9241 uint64_t TSize = Info.Ctx.getTypeSizeInChars(T).getQuantity();
9242 if (!WChar) {
9243 uint64_t Remainder;
9244 llvm::APInt OrigN = N;
9245 llvm::APInt::udivrem(OrigN, TSize, N, Remainder);
9246 if (Remainder) {
9247 Info.FFDiag(E, diag::note_constexpr_memcpy_unsupported)
9248 << Move << WChar << 0 << T << OrigN.toString(10, /*Signed*/false)
9249 << (unsigned)TSize;
9250 return false;
9251 }
9252 }
9253
9254 // Check that the copying will remain within the arrays, just so that we
9255 // can give a more meaningful diagnostic. This implicitly also checks that
9256 // N fits into 64 bits.
9257 uint64_t RemainingSrcSize = Src.Designator.validIndexAdjustments().second;
9258 uint64_t RemainingDestSize = Dest.Designator.validIndexAdjustments().second;
9259 if (N.ugt(RemainingSrcSize) || N.ugt(RemainingDestSize)) {
9260 Info.FFDiag(E, diag::note_constexpr_memcpy_unsupported)
9261 << Move << WChar << (N.ugt(RemainingSrcSize) ? 1 : 2) << T
9262 << N.toString(10, /*Signed*/false);
9263 return false;
9264 }
9265 uint64_t NElems = N.getZExtValue();
9266 uint64_t NBytes = NElems * TSize;
9267
9268 // Check for overlap.
9269 int Direction = 1;
9270 if (HasSameBase(Src, Dest)) {
9271 uint64_t SrcOffset = Src.getLValueOffset().getQuantity();
9272 uint64_t DestOffset = Dest.getLValueOffset().getQuantity();
9273 if (DestOffset >= SrcOffset && DestOffset - SrcOffset < NBytes) {
9274 // Dest is inside the source region.
9275 if (!Move) {
9276 Info.FFDiag(E, diag::note_constexpr_memcpy_overlap) << WChar;
9277 return false;
9278 }
9279 // For memmove and friends, copy backwards.
9280 if (!HandleLValueArrayAdjustment(Info, E, Src, T, NElems - 1) ||
9281 !HandleLValueArrayAdjustment(Info, E, Dest, T, NElems - 1))
9282 return false;
9283 Direction = -1;
9284 } else if (!Move && SrcOffset >= DestOffset &&
9285 SrcOffset - DestOffset < NBytes) {
9286 // Src is inside the destination region for memcpy: invalid.
9287 Info.FFDiag(E, diag::note_constexpr_memcpy_overlap) << WChar;
9288 return false;
9289 }
9290 }
9291
9292 while (true) {
9293 APValue Val;
9294 // FIXME: Set WantObjectRepresentation to true if we're copying a
9295 // char-like type?
9296 if (!handleLValueToRValueConversion(Info, E, T, Src, Val) ||
9297 !handleAssignment(Info, E, Dest, T, Val))
9298 return false;
9299 // Do not iterate past the last element; if we're copying backwards, that
9300 // might take us off the start of the array.
9301 if (--NElems == 0)
9302 return true;
9303 if (!HandleLValueArrayAdjustment(Info, E, Src, T, Direction) ||
9304 !HandleLValueArrayAdjustment(Info, E, Dest, T, Direction))
9305 return false;
9306 }
9307 }
9308
9309 default:
9310 break;
9311 }
9312
9313 return visitNonBuiltinCallExpr(E);
9314 }
9315
9316 static bool EvaluateArrayNewInitList(EvalInfo &Info, LValue &This,
9317 APValue &Result, const InitListExpr *ILE,
9318 QualType AllocType);
9319 static bool EvaluateArrayNewConstructExpr(EvalInfo &Info, LValue &This,
9320 APValue &Result,
9321 const CXXConstructExpr *CCE,
9322 QualType AllocType);
9323
VisitCXXNewExpr(const CXXNewExpr * E)9324 bool PointerExprEvaluator::VisitCXXNewExpr(const CXXNewExpr *E) {
9325 if (!Info.getLangOpts().CPlusPlus20)
9326 Info.CCEDiag(E, diag::note_constexpr_new);
9327
9328 // We cannot speculatively evaluate a delete expression.
9329 if (Info.SpeculativeEvaluationDepth)
9330 return false;
9331
9332 FunctionDecl *OperatorNew = E->getOperatorNew();
9333
9334 bool IsNothrow = false;
9335 bool IsPlacement = false;
9336 if (OperatorNew->isReservedGlobalPlacementOperator() &&
9337 Info.CurrentCall->isStdFunction() && !E->isArray()) {
9338 // FIXME Support array placement new.
9339 assert(E->getNumPlacementArgs() == 1);
9340 if (!EvaluatePointer(E->getPlacementArg(0), Result, Info))
9341 return false;
9342 if (Result.Designator.Invalid)
9343 return false;
9344 IsPlacement = true;
9345 } else if (!OperatorNew->isReplaceableGlobalAllocationFunction()) {
9346 Info.FFDiag(E, diag::note_constexpr_new_non_replaceable)
9347 << isa<CXXMethodDecl>(OperatorNew) << OperatorNew;
9348 return false;
9349 } else if (E->getNumPlacementArgs()) {
9350 // The only new-placement list we support is of the form (std::nothrow).
9351 //
9352 // FIXME: There is no restriction on this, but it's not clear that any
9353 // other form makes any sense. We get here for cases such as:
9354 //
9355 // new (std::align_val_t{N}) X(int)
9356 //
9357 // (which should presumably be valid only if N is a multiple of
9358 // alignof(int), and in any case can't be deallocated unless N is
9359 // alignof(X) and X has new-extended alignment).
9360 if (E->getNumPlacementArgs() != 1 ||
9361 !E->getPlacementArg(0)->getType()->isNothrowT())
9362 return Error(E, diag::note_constexpr_new_placement);
9363
9364 LValue Nothrow;
9365 if (!EvaluateLValue(E->getPlacementArg(0), Nothrow, Info))
9366 return false;
9367 IsNothrow = true;
9368 }
9369
9370 const Expr *Init = E->getInitializer();
9371 const InitListExpr *ResizedArrayILE = nullptr;
9372 const CXXConstructExpr *ResizedArrayCCE = nullptr;
9373 bool ValueInit = false;
9374
9375 QualType AllocType = E->getAllocatedType();
9376 if (Optional<const Expr*> ArraySize = E->getArraySize()) {
9377 const Expr *Stripped = *ArraySize;
9378 for (; auto *ICE = dyn_cast<ImplicitCastExpr>(Stripped);
9379 Stripped = ICE->getSubExpr())
9380 if (ICE->getCastKind() != CK_NoOp &&
9381 ICE->getCastKind() != CK_IntegralCast)
9382 break;
9383
9384 llvm::APSInt ArrayBound;
9385 if (!EvaluateInteger(Stripped, ArrayBound, Info))
9386 return false;
9387
9388 // C++ [expr.new]p9:
9389 // The expression is erroneous if:
9390 // -- [...] its value before converting to size_t [or] applying the
9391 // second standard conversion sequence is less than zero
9392 if (ArrayBound.isSigned() && ArrayBound.isNegative()) {
9393 if (IsNothrow)
9394 return ZeroInitialization(E);
9395
9396 Info.FFDiag(*ArraySize, diag::note_constexpr_new_negative)
9397 << ArrayBound << (*ArraySize)->getSourceRange();
9398 return false;
9399 }
9400
9401 // -- its value is such that the size of the allocated object would
9402 // exceed the implementation-defined limit
9403 if (ConstantArrayType::getNumAddressingBits(Info.Ctx, AllocType,
9404 ArrayBound) >
9405 ConstantArrayType::getMaxSizeBits(Info.Ctx)) {
9406 if (IsNothrow)
9407 return ZeroInitialization(E);
9408
9409 Info.FFDiag(*ArraySize, diag::note_constexpr_new_too_large)
9410 << ArrayBound << (*ArraySize)->getSourceRange();
9411 return false;
9412 }
9413
9414 // -- the new-initializer is a braced-init-list and the number of
9415 // array elements for which initializers are provided [...]
9416 // exceeds the number of elements to initialize
9417 if (!Init) {
9418 // No initialization is performed.
9419 } else if (isa<CXXScalarValueInitExpr>(Init) ||
9420 isa<ImplicitValueInitExpr>(Init)) {
9421 ValueInit = true;
9422 } else if (auto *CCE = dyn_cast<CXXConstructExpr>(Init)) {
9423 ResizedArrayCCE = CCE;
9424 } else {
9425 auto *CAT = Info.Ctx.getAsConstantArrayType(Init->getType());
9426 assert(CAT && "unexpected type for array initializer");
9427
9428 unsigned Bits =
9429 std::max(CAT->getSize().getBitWidth(), ArrayBound.getBitWidth());
9430 llvm::APInt InitBound = CAT->getSize().zextOrSelf(Bits);
9431 llvm::APInt AllocBound = ArrayBound.zextOrSelf(Bits);
9432 if (InitBound.ugt(AllocBound)) {
9433 if (IsNothrow)
9434 return ZeroInitialization(E);
9435
9436 Info.FFDiag(*ArraySize, diag::note_constexpr_new_too_small)
9437 << AllocBound.toString(10, /*Signed=*/false)
9438 << InitBound.toString(10, /*Signed=*/false)
9439 << (*ArraySize)->getSourceRange();
9440 return false;
9441 }
9442
9443 // If the sizes differ, we must have an initializer list, and we need
9444 // special handling for this case when we initialize.
9445 if (InitBound != AllocBound)
9446 ResizedArrayILE = cast<InitListExpr>(Init);
9447 }
9448
9449 AllocType = Info.Ctx.getConstantArrayType(AllocType, ArrayBound, nullptr,
9450 ArrayType::Normal, 0);
9451 } else {
9452 assert(!AllocType->isArrayType() &&
9453 "array allocation with non-array new");
9454 }
9455
9456 APValue *Val;
9457 if (IsPlacement) {
9458 AccessKinds AK = AK_Construct;
9459 struct FindObjectHandler {
9460 EvalInfo &Info;
9461 const Expr *E;
9462 QualType AllocType;
9463 const AccessKinds AccessKind;
9464 APValue *Value;
9465
9466 typedef bool result_type;
9467 bool failed() { return false; }
9468 bool found(APValue &Subobj, QualType SubobjType) {
9469 // FIXME: Reject the cases where [basic.life]p8 would not permit the
9470 // old name of the object to be used to name the new object.
9471 if (!Info.Ctx.hasSameUnqualifiedType(SubobjType, AllocType)) {
9472 Info.FFDiag(E, diag::note_constexpr_placement_new_wrong_type) <<
9473 SubobjType << AllocType;
9474 return false;
9475 }
9476 Value = &Subobj;
9477 return true;
9478 }
9479 bool found(APSInt &Value, QualType SubobjType) {
9480 Info.FFDiag(E, diag::note_constexpr_construct_complex_elem);
9481 return false;
9482 }
9483 bool found(APFloat &Value, QualType SubobjType) {
9484 Info.FFDiag(E, diag::note_constexpr_construct_complex_elem);
9485 return false;
9486 }
9487 } Handler = {Info, E, AllocType, AK, nullptr};
9488
9489 CompleteObject Obj = findCompleteObject(Info, E, AK, Result, AllocType);
9490 if (!Obj || !findSubobject(Info, E, Obj, Result.Designator, Handler))
9491 return false;
9492
9493 Val = Handler.Value;
9494
9495 // [basic.life]p1:
9496 // The lifetime of an object o of type T ends when [...] the storage
9497 // which the object occupies is [...] reused by an object that is not
9498 // nested within o (6.6.2).
9499 *Val = APValue();
9500 } else {
9501 // Perform the allocation and obtain a pointer to the resulting object.
9502 Val = Info.createHeapAlloc(E, AllocType, Result);
9503 if (!Val)
9504 return false;
9505 }
9506
9507 if (ValueInit) {
9508 ImplicitValueInitExpr VIE(AllocType);
9509 if (!EvaluateInPlace(*Val, Info, Result, &VIE))
9510 return false;
9511 } else if (ResizedArrayILE) {
9512 if (!EvaluateArrayNewInitList(Info, Result, *Val, ResizedArrayILE,
9513 AllocType))
9514 return false;
9515 } else if (ResizedArrayCCE) {
9516 if (!EvaluateArrayNewConstructExpr(Info, Result, *Val, ResizedArrayCCE,
9517 AllocType))
9518 return false;
9519 } else if (Init) {
9520 if (!EvaluateInPlace(*Val, Info, Result, Init))
9521 return false;
9522 } else if (!getDefaultInitValue(AllocType, *Val)) {
9523 return false;
9524 }
9525
9526 // Array new returns a pointer to the first element, not a pointer to the
9527 // array.
9528 if (auto *AT = AllocType->getAsArrayTypeUnsafe())
9529 Result.addArray(Info, E, cast<ConstantArrayType>(AT));
9530
9531 return true;
9532 }
9533 //===----------------------------------------------------------------------===//
9534 // Member Pointer Evaluation
9535 //===----------------------------------------------------------------------===//
9536
9537 namespace {
9538 class MemberPointerExprEvaluator
9539 : public ExprEvaluatorBase<MemberPointerExprEvaluator> {
9540 MemberPtr &Result;
9541
Success(const ValueDecl * D)9542 bool Success(const ValueDecl *D) {
9543 Result = MemberPtr(D);
9544 return true;
9545 }
9546 public:
9547
MemberPointerExprEvaluator(EvalInfo & Info,MemberPtr & Result)9548 MemberPointerExprEvaluator(EvalInfo &Info, MemberPtr &Result)
9549 : ExprEvaluatorBaseTy(Info), Result(Result) {}
9550
Success(const APValue & V,const Expr * E)9551 bool Success(const APValue &V, const Expr *E) {
9552 Result.setFrom(V);
9553 return true;
9554 }
ZeroInitialization(const Expr * E)9555 bool ZeroInitialization(const Expr *E) {
9556 return Success((const ValueDecl*)nullptr);
9557 }
9558
9559 bool VisitCastExpr(const CastExpr *E);
9560 bool VisitUnaryAddrOf(const UnaryOperator *E);
9561 };
9562 } // end anonymous namespace
9563
EvaluateMemberPointer(const Expr * E,MemberPtr & Result,EvalInfo & Info)9564 static bool EvaluateMemberPointer(const Expr *E, MemberPtr &Result,
9565 EvalInfo &Info) {
9566 assert(!E->isValueDependent());
9567 assert(E->isRValue() && E->getType()->isMemberPointerType());
9568 return MemberPointerExprEvaluator(Info, Result).Visit(E);
9569 }
9570
VisitCastExpr(const CastExpr * E)9571 bool MemberPointerExprEvaluator::VisitCastExpr(const CastExpr *E) {
9572 switch (E->getCastKind()) {
9573 default:
9574 return ExprEvaluatorBaseTy::VisitCastExpr(E);
9575
9576 case CK_NullToMemberPointer:
9577 VisitIgnoredValue(E->getSubExpr());
9578 return ZeroInitialization(E);
9579
9580 case CK_BaseToDerivedMemberPointer: {
9581 if (!Visit(E->getSubExpr()))
9582 return false;
9583 if (E->path_empty())
9584 return true;
9585 // Base-to-derived member pointer casts store the path in derived-to-base
9586 // order, so iterate backwards. The CXXBaseSpecifier also provides us with
9587 // the wrong end of the derived->base arc, so stagger the path by one class.
9588 typedef std::reverse_iterator<CastExpr::path_const_iterator> ReverseIter;
9589 for (ReverseIter PathI(E->path_end() - 1), PathE(E->path_begin());
9590 PathI != PathE; ++PathI) {
9591 assert(!(*PathI)->isVirtual() && "memptr cast through vbase");
9592 const CXXRecordDecl *Derived = (*PathI)->getType()->getAsCXXRecordDecl();
9593 if (!Result.castToDerived(Derived))
9594 return Error(E);
9595 }
9596 const Type *FinalTy = E->getType()->castAs<MemberPointerType>()->getClass();
9597 if (!Result.castToDerived(FinalTy->getAsCXXRecordDecl()))
9598 return Error(E);
9599 return true;
9600 }
9601
9602 case CK_DerivedToBaseMemberPointer:
9603 if (!Visit(E->getSubExpr()))
9604 return false;
9605 for (CastExpr::path_const_iterator PathI = E->path_begin(),
9606 PathE = E->path_end(); PathI != PathE; ++PathI) {
9607 assert(!(*PathI)->isVirtual() && "memptr cast through vbase");
9608 const CXXRecordDecl *Base = (*PathI)->getType()->getAsCXXRecordDecl();
9609 if (!Result.castToBase(Base))
9610 return Error(E);
9611 }
9612 return true;
9613 }
9614 }
9615
VisitUnaryAddrOf(const UnaryOperator * E)9616 bool MemberPointerExprEvaluator::VisitUnaryAddrOf(const UnaryOperator *E) {
9617 // C++11 [expr.unary.op]p3 has very strict rules on how the address of a
9618 // member can be formed.
9619 return Success(cast<DeclRefExpr>(E->getSubExpr())->getDecl());
9620 }
9621
9622 //===----------------------------------------------------------------------===//
9623 // Record Evaluation
9624 //===----------------------------------------------------------------------===//
9625
9626 namespace {
9627 class RecordExprEvaluator
9628 : public ExprEvaluatorBase<RecordExprEvaluator> {
9629 const LValue &This;
9630 APValue &Result;
9631 public:
9632
RecordExprEvaluator(EvalInfo & info,const LValue & This,APValue & Result)9633 RecordExprEvaluator(EvalInfo &info, const LValue &This, APValue &Result)
9634 : ExprEvaluatorBaseTy(info), This(This), Result(Result) {}
9635
Success(const APValue & V,const Expr * E)9636 bool Success(const APValue &V, const Expr *E) {
9637 Result = V;
9638 return true;
9639 }
ZeroInitialization(const Expr * E)9640 bool ZeroInitialization(const Expr *E) {
9641 return ZeroInitialization(E, E->getType());
9642 }
9643 bool ZeroInitialization(const Expr *E, QualType T);
9644
VisitCallExpr(const CallExpr * E)9645 bool VisitCallExpr(const CallExpr *E) {
9646 return handleCallExpr(E, Result, &This);
9647 }
9648 bool VisitCastExpr(const CastExpr *E);
9649 bool VisitInitListExpr(const InitListExpr *E);
VisitCXXConstructExpr(const CXXConstructExpr * E)9650 bool VisitCXXConstructExpr(const CXXConstructExpr *E) {
9651 return VisitCXXConstructExpr(E, E->getType());
9652 }
9653 bool VisitLambdaExpr(const LambdaExpr *E);
9654 bool VisitCXXInheritedCtorInitExpr(const CXXInheritedCtorInitExpr *E);
9655 bool VisitCXXConstructExpr(const CXXConstructExpr *E, QualType T);
9656 bool VisitCXXStdInitializerListExpr(const CXXStdInitializerListExpr *E);
9657 bool VisitBinCmp(const BinaryOperator *E);
9658 };
9659 }
9660
9661 /// Perform zero-initialization on an object of non-union class type.
9662 /// C++11 [dcl.init]p5:
9663 /// To zero-initialize an object or reference of type T means:
9664 /// [...]
9665 /// -- if T is a (possibly cv-qualified) non-union class type,
9666 /// each non-static data member and each base-class subobject is
9667 /// zero-initialized
HandleClassZeroInitialization(EvalInfo & Info,const Expr * E,const RecordDecl * RD,const LValue & This,APValue & Result)9668 static bool HandleClassZeroInitialization(EvalInfo &Info, const Expr *E,
9669 const RecordDecl *RD,
9670 const LValue &This, APValue &Result) {
9671 assert(!RD->isUnion() && "Expected non-union class type");
9672 const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(RD);
9673 Result = APValue(APValue::UninitStruct(), CD ? CD->getNumBases() : 0,
9674 std::distance(RD->field_begin(), RD->field_end()));
9675
9676 if (RD->isInvalidDecl()) return false;
9677 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
9678
9679 if (CD) {
9680 unsigned Index = 0;
9681 for (CXXRecordDecl::base_class_const_iterator I = CD->bases_begin(),
9682 End = CD->bases_end(); I != End; ++I, ++Index) {
9683 const CXXRecordDecl *Base = I->getType()->getAsCXXRecordDecl();
9684 LValue Subobject = This;
9685 if (!HandleLValueDirectBase(Info, E, Subobject, CD, Base, &Layout))
9686 return false;
9687 if (!HandleClassZeroInitialization(Info, E, Base, Subobject,
9688 Result.getStructBase(Index)))
9689 return false;
9690 }
9691 }
9692
9693 for (const auto *I : RD->fields()) {
9694 // -- if T is a reference type, no initialization is performed.
9695 if (I->isUnnamedBitfield() || I->getType()->isReferenceType())
9696 continue;
9697
9698 LValue Subobject = This;
9699 if (!HandleLValueMember(Info, E, Subobject, I, &Layout))
9700 return false;
9701
9702 ImplicitValueInitExpr VIE(I->getType());
9703 if (!EvaluateInPlace(
9704 Result.getStructField(I->getFieldIndex()), Info, Subobject, &VIE))
9705 return false;
9706 }
9707
9708 return true;
9709 }
9710
ZeroInitialization(const Expr * E,QualType T)9711 bool RecordExprEvaluator::ZeroInitialization(const Expr *E, QualType T) {
9712 const RecordDecl *RD = T->castAs<RecordType>()->getDecl();
9713 if (RD->isInvalidDecl()) return false;
9714 if (RD->isUnion()) {
9715 // C++11 [dcl.init]p5: If T is a (possibly cv-qualified) union type, the
9716 // object's first non-static named data member is zero-initialized
9717 RecordDecl::field_iterator I = RD->field_begin();
9718 while (I != RD->field_end() && (*I)->isUnnamedBitfield())
9719 ++I;
9720 if (I == RD->field_end()) {
9721 Result = APValue((const FieldDecl*)nullptr);
9722 return true;
9723 }
9724
9725 LValue Subobject = This;
9726 if (!HandleLValueMember(Info, E, Subobject, *I))
9727 return false;
9728 Result = APValue(*I);
9729 ImplicitValueInitExpr VIE(I->getType());
9730 return EvaluateInPlace(Result.getUnionValue(), Info, Subobject, &VIE);
9731 }
9732
9733 if (isa<CXXRecordDecl>(RD) && cast<CXXRecordDecl>(RD)->getNumVBases()) {
9734 Info.FFDiag(E, diag::note_constexpr_virtual_base) << RD;
9735 return false;
9736 }
9737
9738 return HandleClassZeroInitialization(Info, E, RD, This, Result);
9739 }
9740
VisitCastExpr(const CastExpr * E)9741 bool RecordExprEvaluator::VisitCastExpr(const CastExpr *E) {
9742 switch (E->getCastKind()) {
9743 default:
9744 return ExprEvaluatorBaseTy::VisitCastExpr(E);
9745
9746 case CK_ConstructorConversion:
9747 return Visit(E->getSubExpr());
9748
9749 case CK_DerivedToBase:
9750 case CK_UncheckedDerivedToBase: {
9751 APValue DerivedObject;
9752 if (!Evaluate(DerivedObject, Info, E->getSubExpr()))
9753 return false;
9754 if (!DerivedObject.isStruct())
9755 return Error(E->getSubExpr());
9756
9757 // Derived-to-base rvalue conversion: just slice off the derived part.
9758 APValue *Value = &DerivedObject;
9759 const CXXRecordDecl *RD = E->getSubExpr()->getType()->getAsCXXRecordDecl();
9760 for (CastExpr::path_const_iterator PathI = E->path_begin(),
9761 PathE = E->path_end(); PathI != PathE; ++PathI) {
9762 assert(!(*PathI)->isVirtual() && "record rvalue with virtual base");
9763 const CXXRecordDecl *Base = (*PathI)->getType()->getAsCXXRecordDecl();
9764 Value = &Value->getStructBase(getBaseIndex(RD, Base));
9765 RD = Base;
9766 }
9767 Result = *Value;
9768 return true;
9769 }
9770 }
9771 }
9772
VisitInitListExpr(const InitListExpr * E)9773 bool RecordExprEvaluator::VisitInitListExpr(const InitListExpr *E) {
9774 if (E->isTransparent())
9775 return Visit(E->getInit(0));
9776
9777 const RecordDecl *RD = E->getType()->castAs<RecordType>()->getDecl();
9778 if (RD->isInvalidDecl()) return false;
9779 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
9780 auto *CXXRD = dyn_cast<CXXRecordDecl>(RD);
9781
9782 EvalInfo::EvaluatingConstructorRAII EvalObj(
9783 Info,
9784 ObjectUnderConstruction{This.getLValueBase(), This.Designator.Entries},
9785 CXXRD && CXXRD->getNumBases());
9786
9787 if (RD->isUnion()) {
9788 const FieldDecl *Field = E->getInitializedFieldInUnion();
9789 Result = APValue(Field);
9790 if (!Field)
9791 return true;
9792
9793 // If the initializer list for a union does not contain any elements, the
9794 // first element of the union is value-initialized.
9795 // FIXME: The element should be initialized from an initializer list.
9796 // Is this difference ever observable for initializer lists which
9797 // we don't build?
9798 ImplicitValueInitExpr VIE(Field->getType());
9799 const Expr *InitExpr = E->getNumInits() ? E->getInit(0) : &VIE;
9800
9801 LValue Subobject = This;
9802 if (!HandleLValueMember(Info, InitExpr, Subobject, Field, &Layout))
9803 return false;
9804
9805 // Temporarily override This, in case there's a CXXDefaultInitExpr in here.
9806 ThisOverrideRAII ThisOverride(*Info.CurrentCall, &This,
9807 isa<CXXDefaultInitExpr>(InitExpr));
9808
9809 if (EvaluateInPlace(Result.getUnionValue(), Info, Subobject, InitExpr)) {
9810 if (Field->isBitField())
9811 return truncateBitfieldValue(Info, InitExpr, Result.getUnionValue(),
9812 Field);
9813 return true;
9814 }
9815
9816 return false;
9817 }
9818
9819 if (!Result.hasValue())
9820 Result = APValue(APValue::UninitStruct(), CXXRD ? CXXRD->getNumBases() : 0,
9821 std::distance(RD->field_begin(), RD->field_end()));
9822 unsigned ElementNo = 0;
9823 bool Success = true;
9824
9825 // Initialize base classes.
9826 if (CXXRD && CXXRD->getNumBases()) {
9827 for (const auto &Base : CXXRD->bases()) {
9828 assert(ElementNo < E->getNumInits() && "missing init for base class");
9829 const Expr *Init = E->getInit(ElementNo);
9830
9831 LValue Subobject = This;
9832 if (!HandleLValueBase(Info, Init, Subobject, CXXRD, &Base))
9833 return false;
9834
9835 APValue &FieldVal = Result.getStructBase(ElementNo);
9836 if (!EvaluateInPlace(FieldVal, Info, Subobject, Init)) {
9837 if (!Info.noteFailure())
9838 return false;
9839 Success = false;
9840 }
9841 ++ElementNo;
9842 }
9843
9844 EvalObj.finishedConstructingBases();
9845 }
9846
9847 // Initialize members.
9848 for (const auto *Field : RD->fields()) {
9849 // Anonymous bit-fields are not considered members of the class for
9850 // purposes of aggregate initialization.
9851 if (Field->isUnnamedBitfield())
9852 continue;
9853
9854 LValue Subobject = This;
9855
9856 bool HaveInit = ElementNo < E->getNumInits();
9857
9858 // FIXME: Diagnostics here should point to the end of the initializer
9859 // list, not the start.
9860 if (!HandleLValueMember(Info, HaveInit ? E->getInit(ElementNo) : E,
9861 Subobject, Field, &Layout))
9862 return false;
9863
9864 // Perform an implicit value-initialization for members beyond the end of
9865 // the initializer list.
9866 ImplicitValueInitExpr VIE(HaveInit ? Info.Ctx.IntTy : Field->getType());
9867 const Expr *Init = HaveInit ? E->getInit(ElementNo++) : &VIE;
9868
9869 // Temporarily override This, in case there's a CXXDefaultInitExpr in here.
9870 ThisOverrideRAII ThisOverride(*Info.CurrentCall, &This,
9871 isa<CXXDefaultInitExpr>(Init));
9872
9873 APValue &FieldVal = Result.getStructField(Field->getFieldIndex());
9874 if (!EvaluateInPlace(FieldVal, Info, Subobject, Init) ||
9875 (Field->isBitField() && !truncateBitfieldValue(Info, Init,
9876 FieldVal, Field))) {
9877 if (!Info.noteFailure())
9878 return false;
9879 Success = false;
9880 }
9881 }
9882
9883 EvalObj.finishedConstructingFields();
9884
9885 return Success;
9886 }
9887
VisitCXXConstructExpr(const CXXConstructExpr * E,QualType T)9888 bool RecordExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E,
9889 QualType T) {
9890 // Note that E's type is not necessarily the type of our class here; we might
9891 // be initializing an array element instead.
9892 const CXXConstructorDecl *FD = E->getConstructor();
9893 if (FD->isInvalidDecl() || FD->getParent()->isInvalidDecl()) return false;
9894
9895 bool ZeroInit = E->requiresZeroInitialization();
9896 if (CheckTrivialDefaultConstructor(Info, E->getExprLoc(), FD, ZeroInit)) {
9897 // If we've already performed zero-initialization, we're already done.
9898 if (Result.hasValue())
9899 return true;
9900
9901 if (ZeroInit)
9902 return ZeroInitialization(E, T);
9903
9904 return getDefaultInitValue(T, Result);
9905 }
9906
9907 const FunctionDecl *Definition = nullptr;
9908 auto Body = FD->getBody(Definition);
9909
9910 if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition, Body))
9911 return false;
9912
9913 // Avoid materializing a temporary for an elidable copy/move constructor.
9914 if (E->isElidable() && !ZeroInit)
9915 if (const MaterializeTemporaryExpr *ME
9916 = dyn_cast<MaterializeTemporaryExpr>(E->getArg(0)))
9917 return Visit(ME->getSubExpr());
9918
9919 if (ZeroInit && !ZeroInitialization(E, T))
9920 return false;
9921
9922 auto Args = llvm::makeArrayRef(E->getArgs(), E->getNumArgs());
9923 return HandleConstructorCall(E, This, Args,
9924 cast<CXXConstructorDecl>(Definition), Info,
9925 Result);
9926 }
9927
VisitCXXInheritedCtorInitExpr(const CXXInheritedCtorInitExpr * E)9928 bool RecordExprEvaluator::VisitCXXInheritedCtorInitExpr(
9929 const CXXInheritedCtorInitExpr *E) {
9930 if (!Info.CurrentCall) {
9931 assert(Info.checkingPotentialConstantExpression());
9932 return false;
9933 }
9934
9935 const CXXConstructorDecl *FD = E->getConstructor();
9936 if (FD->isInvalidDecl() || FD->getParent()->isInvalidDecl())
9937 return false;
9938
9939 const FunctionDecl *Definition = nullptr;
9940 auto Body = FD->getBody(Definition);
9941
9942 if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition, Body))
9943 return false;
9944
9945 return HandleConstructorCall(E, This, Info.CurrentCall->Arguments,
9946 cast<CXXConstructorDecl>(Definition), Info,
9947 Result);
9948 }
9949
VisitCXXStdInitializerListExpr(const CXXStdInitializerListExpr * E)9950 bool RecordExprEvaluator::VisitCXXStdInitializerListExpr(
9951 const CXXStdInitializerListExpr *E) {
9952 const ConstantArrayType *ArrayType =
9953 Info.Ctx.getAsConstantArrayType(E->getSubExpr()->getType());
9954
9955 LValue Array;
9956 if (!EvaluateLValue(E->getSubExpr(), Array, Info))
9957 return false;
9958
9959 // Get a pointer to the first element of the array.
9960 Array.addArray(Info, E, ArrayType);
9961
9962 auto InvalidType = [&] {
9963 Info.FFDiag(E, diag::note_constexpr_unsupported_layout)
9964 << E->getType();
9965 return false;
9966 };
9967
9968 // FIXME: Perform the checks on the field types in SemaInit.
9969 RecordDecl *Record = E->getType()->castAs<RecordType>()->getDecl();
9970 RecordDecl::field_iterator Field = Record->field_begin();
9971 if (Field == Record->field_end())
9972 return InvalidType();
9973
9974 // Start pointer.
9975 if (!Field->getType()->isPointerType() ||
9976 !Info.Ctx.hasSameType(Field->getType()->getPointeeType(),
9977 ArrayType->getElementType()))
9978 return InvalidType();
9979
9980 // FIXME: What if the initializer_list type has base classes, etc?
9981 Result = APValue(APValue::UninitStruct(), 0, 2);
9982 Array.moveInto(Result.getStructField(0));
9983
9984 if (++Field == Record->field_end())
9985 return InvalidType();
9986
9987 if (Field->getType()->isPointerType() &&
9988 Info.Ctx.hasSameType(Field->getType()->getPointeeType(),
9989 ArrayType->getElementType())) {
9990 // End pointer.
9991 if (!HandleLValueArrayAdjustment(Info, E, Array,
9992 ArrayType->getElementType(),
9993 ArrayType->getSize().getZExtValue()))
9994 return false;
9995 Array.moveInto(Result.getStructField(1));
9996 } else if (Info.Ctx.hasSameType(Field->getType(), Info.Ctx.getSizeType()))
9997 // Length.
9998 Result.getStructField(1) = APValue(APSInt(ArrayType->getSize()));
9999 else
10000 return InvalidType();
10001
10002 if (++Field != Record->field_end())
10003 return InvalidType();
10004
10005 return true;
10006 }
10007
VisitLambdaExpr(const LambdaExpr * E)10008 bool RecordExprEvaluator::VisitLambdaExpr(const LambdaExpr *E) {
10009 const CXXRecordDecl *ClosureClass = E->getLambdaClass();
10010 if (ClosureClass->isInvalidDecl())
10011 return false;
10012
10013 const size_t NumFields =
10014 std::distance(ClosureClass->field_begin(), ClosureClass->field_end());
10015
10016 assert(NumFields == (size_t)std::distance(E->capture_init_begin(),
10017 E->capture_init_end()) &&
10018 "The number of lambda capture initializers should equal the number of "
10019 "fields within the closure type");
10020
10021 Result = APValue(APValue::UninitStruct(), /*NumBases*/0, NumFields);
10022 // Iterate through all the lambda's closure object's fields and initialize
10023 // them.
10024 auto *CaptureInitIt = E->capture_init_begin();
10025 const LambdaCapture *CaptureIt = ClosureClass->captures_begin();
10026 bool Success = true;
10027 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(ClosureClass);
10028 for (const auto *Field : ClosureClass->fields()) {
10029 assert(CaptureInitIt != E->capture_init_end());
10030 // Get the initializer for this field
10031 Expr *const CurFieldInit = *CaptureInitIt++;
10032
10033 // If there is no initializer, either this is a VLA or an error has
10034 // occurred.
10035 if (!CurFieldInit)
10036 return Error(E);
10037
10038 LValue Subobject = This;
10039
10040 if (!HandleLValueMember(Info, E, Subobject, Field, &Layout))
10041 return false;
10042
10043 APValue &FieldVal = Result.getStructField(Field->getFieldIndex());
10044 if (!EvaluateInPlace(FieldVal, Info, Subobject, CurFieldInit)) {
10045 if (!Info.keepEvaluatingAfterFailure())
10046 return false;
10047 Success = false;
10048 }
10049 ++CaptureIt;
10050 }
10051 return Success;
10052 }
10053
EvaluateRecord(const Expr * E,const LValue & This,APValue & Result,EvalInfo & Info)10054 static bool EvaluateRecord(const Expr *E, const LValue &This,
10055 APValue &Result, EvalInfo &Info) {
10056 assert(!E->isValueDependent());
10057 assert(E->isRValue() && E->getType()->isRecordType() &&
10058 "can't evaluate expression as a record rvalue");
10059 return RecordExprEvaluator(Info, This, Result).Visit(E);
10060 }
10061
10062 //===----------------------------------------------------------------------===//
10063 // Temporary Evaluation
10064 //
10065 // Temporaries are represented in the AST as rvalues, but generally behave like
10066 // lvalues. The full-object of which the temporary is a subobject is implicitly
10067 // materialized so that a reference can bind to it.
10068 //===----------------------------------------------------------------------===//
10069 namespace {
10070 class TemporaryExprEvaluator
10071 : public LValueExprEvaluatorBase<TemporaryExprEvaluator> {
10072 public:
TemporaryExprEvaluator(EvalInfo & Info,LValue & Result)10073 TemporaryExprEvaluator(EvalInfo &Info, LValue &Result) :
10074 LValueExprEvaluatorBaseTy(Info, Result, false) {}
10075
10076 /// Visit an expression which constructs the value of this temporary.
VisitConstructExpr(const Expr * E)10077 bool VisitConstructExpr(const Expr *E) {
10078 APValue &Value = Info.CurrentCall->createTemporary(
10079 E, E->getType(), ScopeKind::FullExpression, Result);
10080 return EvaluateInPlace(Value, Info, Result, E);
10081 }
10082
VisitCastExpr(const CastExpr * E)10083 bool VisitCastExpr(const CastExpr *E) {
10084 switch (E->getCastKind()) {
10085 default:
10086 return LValueExprEvaluatorBaseTy::VisitCastExpr(E);
10087
10088 case CK_ConstructorConversion:
10089 return VisitConstructExpr(E->getSubExpr());
10090 }
10091 }
VisitInitListExpr(const InitListExpr * E)10092 bool VisitInitListExpr(const InitListExpr *E) {
10093 return VisitConstructExpr(E);
10094 }
VisitCXXConstructExpr(const CXXConstructExpr * E)10095 bool VisitCXXConstructExpr(const CXXConstructExpr *E) {
10096 return VisitConstructExpr(E);
10097 }
VisitCallExpr(const CallExpr * E)10098 bool VisitCallExpr(const CallExpr *E) {
10099 return VisitConstructExpr(E);
10100 }
VisitCXXStdInitializerListExpr(const CXXStdInitializerListExpr * E)10101 bool VisitCXXStdInitializerListExpr(const CXXStdInitializerListExpr *E) {
10102 return VisitConstructExpr(E);
10103 }
VisitLambdaExpr(const LambdaExpr * E)10104 bool VisitLambdaExpr(const LambdaExpr *E) {
10105 return VisitConstructExpr(E);
10106 }
10107 };
10108 } // end anonymous namespace
10109
10110 /// Evaluate an expression of record type as a temporary.
EvaluateTemporary(const Expr * E,LValue & Result,EvalInfo & Info)10111 static bool EvaluateTemporary(const Expr *E, LValue &Result, EvalInfo &Info) {
10112 assert(!E->isValueDependent());
10113 assert(E->isRValue() && E->getType()->isRecordType());
10114 return TemporaryExprEvaluator(Info, Result).Visit(E);
10115 }
10116
10117 //===----------------------------------------------------------------------===//
10118 // Vector Evaluation
10119 //===----------------------------------------------------------------------===//
10120
10121 namespace {
10122 class VectorExprEvaluator
10123 : public ExprEvaluatorBase<VectorExprEvaluator> {
10124 APValue &Result;
10125 public:
10126
VectorExprEvaluator(EvalInfo & info,APValue & Result)10127 VectorExprEvaluator(EvalInfo &info, APValue &Result)
10128 : ExprEvaluatorBaseTy(info), Result(Result) {}
10129
Success(ArrayRef<APValue> V,const Expr * E)10130 bool Success(ArrayRef<APValue> V, const Expr *E) {
10131 assert(V.size() == E->getType()->castAs<VectorType>()->getNumElements());
10132 // FIXME: remove this APValue copy.
10133 Result = APValue(V.data(), V.size());
10134 return true;
10135 }
Success(const APValue & V,const Expr * E)10136 bool Success(const APValue &V, const Expr *E) {
10137 assert(V.isVector());
10138 Result = V;
10139 return true;
10140 }
10141 bool ZeroInitialization(const Expr *E);
10142
VisitUnaryReal(const UnaryOperator * E)10143 bool VisitUnaryReal(const UnaryOperator *E)
10144 { return Visit(E->getSubExpr()); }
10145 bool VisitCastExpr(const CastExpr* E);
10146 bool VisitInitListExpr(const InitListExpr *E);
10147 bool VisitUnaryImag(const UnaryOperator *E);
10148 bool VisitBinaryOperator(const BinaryOperator *E);
10149 // FIXME: Missing: unary -, unary ~, conditional operator (for GNU
10150 // conditional select), shufflevector, ExtVectorElementExpr
10151 };
10152 } // end anonymous namespace
10153
EvaluateVector(const Expr * E,APValue & Result,EvalInfo & Info)10154 static bool EvaluateVector(const Expr* E, APValue& Result, EvalInfo &Info) {
10155 assert(E->isRValue() && E->getType()->isVectorType() &&"not a vector rvalue");
10156 return VectorExprEvaluator(Info, Result).Visit(E);
10157 }
10158
VisitCastExpr(const CastExpr * E)10159 bool VectorExprEvaluator::VisitCastExpr(const CastExpr *E) {
10160 const VectorType *VTy = E->getType()->castAs<VectorType>();
10161 unsigned NElts = VTy->getNumElements();
10162
10163 const Expr *SE = E->getSubExpr();
10164 QualType SETy = SE->getType();
10165
10166 switch (E->getCastKind()) {
10167 case CK_VectorSplat: {
10168 APValue Val = APValue();
10169 if (SETy->isIntegerType()) {
10170 APSInt IntResult;
10171 if (!EvaluateInteger(SE, IntResult, Info))
10172 return false;
10173 Val = APValue(std::move(IntResult));
10174 } else if (SETy->isRealFloatingType()) {
10175 APFloat FloatResult(0.0);
10176 if (!EvaluateFloat(SE, FloatResult, Info))
10177 return false;
10178 Val = APValue(std::move(FloatResult));
10179 } else {
10180 return Error(E);
10181 }
10182
10183 // Splat and create vector APValue.
10184 SmallVector<APValue, 4> Elts(NElts, Val);
10185 return Success(Elts, E);
10186 }
10187 case CK_BitCast: {
10188 // Evaluate the operand into an APInt we can extract from.
10189 llvm::APInt SValInt;
10190 if (!EvalAndBitcastToAPInt(Info, SE, SValInt))
10191 return false;
10192 // Extract the elements
10193 QualType EltTy = VTy->getElementType();
10194 unsigned EltSize = Info.Ctx.getTypeSize(EltTy);
10195 bool BigEndian = Info.Ctx.getTargetInfo().isBigEndian();
10196 SmallVector<APValue, 4> Elts;
10197 if (EltTy->isRealFloatingType()) {
10198 const llvm::fltSemantics &Sem = Info.Ctx.getFloatTypeSemantics(EltTy);
10199 unsigned FloatEltSize = EltSize;
10200 if (&Sem == &APFloat::x87DoubleExtended())
10201 FloatEltSize = 80;
10202 for (unsigned i = 0; i < NElts; i++) {
10203 llvm::APInt Elt;
10204 if (BigEndian)
10205 Elt = SValInt.rotl(i*EltSize+FloatEltSize).trunc(FloatEltSize);
10206 else
10207 Elt = SValInt.rotr(i*EltSize).trunc(FloatEltSize);
10208 Elts.push_back(APValue(APFloat(Sem, Elt)));
10209 }
10210 } else if (EltTy->isIntegerType()) {
10211 for (unsigned i = 0; i < NElts; i++) {
10212 llvm::APInt Elt;
10213 if (BigEndian)
10214 Elt = SValInt.rotl(i*EltSize+EltSize).zextOrTrunc(EltSize);
10215 else
10216 Elt = SValInt.rotr(i*EltSize).zextOrTrunc(EltSize);
10217 Elts.push_back(APValue(APSInt(Elt, !EltTy->isSignedIntegerType())));
10218 }
10219 } else {
10220 return Error(E);
10221 }
10222 return Success(Elts, E);
10223 }
10224 default:
10225 return ExprEvaluatorBaseTy::VisitCastExpr(E);
10226 }
10227 }
10228
10229 bool
VisitInitListExpr(const InitListExpr * E)10230 VectorExprEvaluator::VisitInitListExpr(const InitListExpr *E) {
10231 const VectorType *VT = E->getType()->castAs<VectorType>();
10232 unsigned NumInits = E->getNumInits();
10233 unsigned NumElements = VT->getNumElements();
10234
10235 QualType EltTy = VT->getElementType();
10236 SmallVector<APValue, 4> Elements;
10237
10238 // The number of initializers can be less than the number of
10239 // vector elements. For OpenCL, this can be due to nested vector
10240 // initialization. For GCC compatibility, missing trailing elements
10241 // should be initialized with zeroes.
10242 unsigned CountInits = 0, CountElts = 0;
10243 while (CountElts < NumElements) {
10244 // Handle nested vector initialization.
10245 if (CountInits < NumInits
10246 && E->getInit(CountInits)->getType()->isVectorType()) {
10247 APValue v;
10248 if (!EvaluateVector(E->getInit(CountInits), v, Info))
10249 return Error(E);
10250 unsigned vlen = v.getVectorLength();
10251 for (unsigned j = 0; j < vlen; j++)
10252 Elements.push_back(v.getVectorElt(j));
10253 CountElts += vlen;
10254 } else if (EltTy->isIntegerType()) {
10255 llvm::APSInt sInt(32);
10256 if (CountInits < NumInits) {
10257 if (!EvaluateInteger(E->getInit(CountInits), sInt, Info))
10258 return false;
10259 } else // trailing integer zero.
10260 sInt = Info.Ctx.MakeIntValue(0, EltTy);
10261 Elements.push_back(APValue(sInt));
10262 CountElts++;
10263 } else {
10264 llvm::APFloat f(0.0);
10265 if (CountInits < NumInits) {
10266 if (!EvaluateFloat(E->getInit(CountInits), f, Info))
10267 return false;
10268 } else // trailing float zero.
10269 f = APFloat::getZero(Info.Ctx.getFloatTypeSemantics(EltTy));
10270 Elements.push_back(APValue(f));
10271 CountElts++;
10272 }
10273 CountInits++;
10274 }
10275 return Success(Elements, E);
10276 }
10277
10278 bool
ZeroInitialization(const Expr * E)10279 VectorExprEvaluator::ZeroInitialization(const Expr *E) {
10280 const auto *VT = E->getType()->castAs<VectorType>();
10281 QualType EltTy = VT->getElementType();
10282 APValue ZeroElement;
10283 if (EltTy->isIntegerType())
10284 ZeroElement = APValue(Info.Ctx.MakeIntValue(0, EltTy));
10285 else
10286 ZeroElement =
10287 APValue(APFloat::getZero(Info.Ctx.getFloatTypeSemantics(EltTy)));
10288
10289 SmallVector<APValue, 4> Elements(VT->getNumElements(), ZeroElement);
10290 return Success(Elements, E);
10291 }
10292
VisitUnaryImag(const UnaryOperator * E)10293 bool VectorExprEvaluator::VisitUnaryImag(const UnaryOperator *E) {
10294 VisitIgnoredValue(E->getSubExpr());
10295 return ZeroInitialization(E);
10296 }
10297
VisitBinaryOperator(const BinaryOperator * E)10298 bool VectorExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
10299 BinaryOperatorKind Op = E->getOpcode();
10300 assert(Op != BO_PtrMemD && Op != BO_PtrMemI && Op != BO_Cmp &&
10301 "Operation not supported on vector types");
10302
10303 if (Op == BO_Comma)
10304 return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
10305
10306 Expr *LHS = E->getLHS();
10307 Expr *RHS = E->getRHS();
10308
10309 assert(LHS->getType()->isVectorType() && RHS->getType()->isVectorType() &&
10310 "Must both be vector types");
10311 // Checking JUST the types are the same would be fine, except shifts don't
10312 // need to have their types be the same (since you always shift by an int).
10313 assert(LHS->getType()->castAs<VectorType>()->getNumElements() ==
10314 E->getType()->castAs<VectorType>()->getNumElements() &&
10315 RHS->getType()->castAs<VectorType>()->getNumElements() ==
10316 E->getType()->castAs<VectorType>()->getNumElements() &&
10317 "All operands must be the same size.");
10318
10319 APValue LHSValue;
10320 APValue RHSValue;
10321 bool LHSOK = Evaluate(LHSValue, Info, LHS);
10322 if (!LHSOK && !Info.noteFailure())
10323 return false;
10324 if (!Evaluate(RHSValue, Info, RHS) || !LHSOK)
10325 return false;
10326
10327 if (!handleVectorVectorBinOp(Info, E, Op, LHSValue, RHSValue))
10328 return false;
10329
10330 return Success(LHSValue, E);
10331 }
10332
10333 //===----------------------------------------------------------------------===//
10334 // Array Evaluation
10335 //===----------------------------------------------------------------------===//
10336
10337 namespace {
10338 class ArrayExprEvaluator
10339 : public ExprEvaluatorBase<ArrayExprEvaluator> {
10340 const LValue &This;
10341 APValue &Result;
10342 public:
10343
ArrayExprEvaluator(EvalInfo & Info,const LValue & This,APValue & Result)10344 ArrayExprEvaluator(EvalInfo &Info, const LValue &This, APValue &Result)
10345 : ExprEvaluatorBaseTy(Info), This(This), Result(Result) {}
10346
Success(const APValue & V,const Expr * E)10347 bool Success(const APValue &V, const Expr *E) {
10348 assert(V.isArray() && "expected array");
10349 Result = V;
10350 return true;
10351 }
10352
ZeroInitialization(const Expr * E)10353 bool ZeroInitialization(const Expr *E) {
10354 const ConstantArrayType *CAT =
10355 Info.Ctx.getAsConstantArrayType(E->getType());
10356 if (!CAT) {
10357 if (E->getType()->isIncompleteArrayType()) {
10358 // We can be asked to zero-initialize a flexible array member; this
10359 // is represented as an ImplicitValueInitExpr of incomplete array
10360 // type. In this case, the array has zero elements.
10361 Result = APValue(APValue::UninitArray(), 0, 0);
10362 return true;
10363 }
10364 // FIXME: We could handle VLAs here.
10365 return Error(E);
10366 }
10367
10368 Result = APValue(APValue::UninitArray(), 0,
10369 CAT->getSize().getZExtValue());
10370 if (!Result.hasArrayFiller()) return true;
10371
10372 // Zero-initialize all elements.
10373 LValue Subobject = This;
10374 Subobject.addArray(Info, E, CAT);
10375 ImplicitValueInitExpr VIE(CAT->getElementType());
10376 return EvaluateInPlace(Result.getArrayFiller(), Info, Subobject, &VIE);
10377 }
10378
VisitCallExpr(const CallExpr * E)10379 bool VisitCallExpr(const CallExpr *E) {
10380 return handleCallExpr(E, Result, &This);
10381 }
10382 bool VisitInitListExpr(const InitListExpr *E,
10383 QualType AllocType = QualType());
10384 bool VisitArrayInitLoopExpr(const ArrayInitLoopExpr *E);
10385 bool VisitCXXConstructExpr(const CXXConstructExpr *E);
10386 bool VisitCXXConstructExpr(const CXXConstructExpr *E,
10387 const LValue &Subobject,
10388 APValue *Value, QualType Type);
VisitStringLiteral(const StringLiteral * E,QualType AllocType=QualType ())10389 bool VisitStringLiteral(const StringLiteral *E,
10390 QualType AllocType = QualType()) {
10391 expandStringLiteral(Info, E, Result, AllocType);
10392 return true;
10393 }
10394 };
10395 } // end anonymous namespace
10396
EvaluateArray(const Expr * E,const LValue & This,APValue & Result,EvalInfo & Info)10397 static bool EvaluateArray(const Expr *E, const LValue &This,
10398 APValue &Result, EvalInfo &Info) {
10399 assert(!E->isValueDependent());
10400 assert(E->isRValue() && E->getType()->isArrayType() && "not an array rvalue");
10401 return ArrayExprEvaluator(Info, This, Result).Visit(E);
10402 }
10403
EvaluateArrayNewInitList(EvalInfo & Info,LValue & This,APValue & Result,const InitListExpr * ILE,QualType AllocType)10404 static bool EvaluateArrayNewInitList(EvalInfo &Info, LValue &This,
10405 APValue &Result, const InitListExpr *ILE,
10406 QualType AllocType) {
10407 assert(!ILE->isValueDependent());
10408 assert(ILE->isRValue() && ILE->getType()->isArrayType() &&
10409 "not an array rvalue");
10410 return ArrayExprEvaluator(Info, This, Result)
10411 .VisitInitListExpr(ILE, AllocType);
10412 }
10413
EvaluateArrayNewConstructExpr(EvalInfo & Info,LValue & This,APValue & Result,const CXXConstructExpr * CCE,QualType AllocType)10414 static bool EvaluateArrayNewConstructExpr(EvalInfo &Info, LValue &This,
10415 APValue &Result,
10416 const CXXConstructExpr *CCE,
10417 QualType AllocType) {
10418 assert(!CCE->isValueDependent());
10419 assert(CCE->isRValue() && CCE->getType()->isArrayType() &&
10420 "not an array rvalue");
10421 return ArrayExprEvaluator(Info, This, Result)
10422 .VisitCXXConstructExpr(CCE, This, &Result, AllocType);
10423 }
10424
10425 // Return true iff the given array filler may depend on the element index.
MaybeElementDependentArrayFiller(const Expr * FillerExpr)10426 static bool MaybeElementDependentArrayFiller(const Expr *FillerExpr) {
10427 // For now, just allow non-class value-initialization and initialization
10428 // lists comprised of them.
10429 if (isa<ImplicitValueInitExpr>(FillerExpr))
10430 return false;
10431 if (const InitListExpr *ILE = dyn_cast<InitListExpr>(FillerExpr)) {
10432 for (unsigned I = 0, E = ILE->getNumInits(); I != E; ++I) {
10433 if (MaybeElementDependentArrayFiller(ILE->getInit(I)))
10434 return true;
10435 }
10436 return false;
10437 }
10438 return true;
10439 }
10440
VisitInitListExpr(const InitListExpr * E,QualType AllocType)10441 bool ArrayExprEvaluator::VisitInitListExpr(const InitListExpr *E,
10442 QualType AllocType) {
10443 const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(
10444 AllocType.isNull() ? E->getType() : AllocType);
10445 if (!CAT)
10446 return Error(E);
10447
10448 // C++11 [dcl.init.string]p1: A char array [...] can be initialized by [...]
10449 // an appropriately-typed string literal enclosed in braces.
10450 if (E->isStringLiteralInit()) {
10451 auto *SL = dyn_cast<StringLiteral>(E->getInit(0)->IgnoreParens());
10452 // FIXME: Support ObjCEncodeExpr here once we support it in
10453 // ArrayExprEvaluator generally.
10454 if (!SL)
10455 return Error(E);
10456 return VisitStringLiteral(SL, AllocType);
10457 }
10458
10459 bool Success = true;
10460
10461 assert((!Result.isArray() || Result.getArrayInitializedElts() == 0) &&
10462 "zero-initialized array shouldn't have any initialized elts");
10463 APValue Filler;
10464 if (Result.isArray() && Result.hasArrayFiller())
10465 Filler = Result.getArrayFiller();
10466
10467 unsigned NumEltsToInit = E->getNumInits();
10468 unsigned NumElts = CAT->getSize().getZExtValue();
10469 const Expr *FillerExpr = E->hasArrayFiller() ? E->getArrayFiller() : nullptr;
10470
10471 // If the initializer might depend on the array index, run it for each
10472 // array element.
10473 if (NumEltsToInit != NumElts && MaybeElementDependentArrayFiller(FillerExpr))
10474 NumEltsToInit = NumElts;
10475
10476 LLVM_DEBUG(llvm::dbgs() << "The number of elements to initialize: "
10477 << NumEltsToInit << ".\n");
10478
10479 Result = APValue(APValue::UninitArray(), NumEltsToInit, NumElts);
10480
10481 // If the array was previously zero-initialized, preserve the
10482 // zero-initialized values.
10483 if (Filler.hasValue()) {
10484 for (unsigned I = 0, E = Result.getArrayInitializedElts(); I != E; ++I)
10485 Result.getArrayInitializedElt(I) = Filler;
10486 if (Result.hasArrayFiller())
10487 Result.getArrayFiller() = Filler;
10488 }
10489
10490 LValue Subobject = This;
10491 Subobject.addArray(Info, E, CAT);
10492 for (unsigned Index = 0; Index != NumEltsToInit; ++Index) {
10493 const Expr *Init =
10494 Index < E->getNumInits() ? E->getInit(Index) : FillerExpr;
10495 if (!EvaluateInPlace(Result.getArrayInitializedElt(Index),
10496 Info, Subobject, Init) ||
10497 !HandleLValueArrayAdjustment(Info, Init, Subobject,
10498 CAT->getElementType(), 1)) {
10499 if (!Info.noteFailure())
10500 return false;
10501 Success = false;
10502 }
10503 }
10504
10505 if (!Result.hasArrayFiller())
10506 return Success;
10507
10508 // If we get here, we have a trivial filler, which we can just evaluate
10509 // once and splat over the rest of the array elements.
10510 assert(FillerExpr && "no array filler for incomplete init list");
10511 return EvaluateInPlace(Result.getArrayFiller(), Info, Subobject,
10512 FillerExpr) && Success;
10513 }
10514
VisitArrayInitLoopExpr(const ArrayInitLoopExpr * E)10515 bool ArrayExprEvaluator::VisitArrayInitLoopExpr(const ArrayInitLoopExpr *E) {
10516 LValue CommonLV;
10517 if (E->getCommonExpr() &&
10518 !Evaluate(Info.CurrentCall->createTemporary(
10519 E->getCommonExpr(),
10520 getStorageType(Info.Ctx, E->getCommonExpr()),
10521 ScopeKind::FullExpression, CommonLV),
10522 Info, E->getCommonExpr()->getSourceExpr()))
10523 return false;
10524
10525 auto *CAT = cast<ConstantArrayType>(E->getType()->castAsArrayTypeUnsafe());
10526
10527 uint64_t Elements = CAT->getSize().getZExtValue();
10528 Result = APValue(APValue::UninitArray(), Elements, Elements);
10529
10530 LValue Subobject = This;
10531 Subobject.addArray(Info, E, CAT);
10532
10533 bool Success = true;
10534 for (EvalInfo::ArrayInitLoopIndex Index(Info); Index != Elements; ++Index) {
10535 if (!EvaluateInPlace(Result.getArrayInitializedElt(Index),
10536 Info, Subobject, E->getSubExpr()) ||
10537 !HandleLValueArrayAdjustment(Info, E, Subobject,
10538 CAT->getElementType(), 1)) {
10539 if (!Info.noteFailure())
10540 return false;
10541 Success = false;
10542 }
10543 }
10544
10545 return Success;
10546 }
10547
VisitCXXConstructExpr(const CXXConstructExpr * E)10548 bool ArrayExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E) {
10549 return VisitCXXConstructExpr(E, This, &Result, E->getType());
10550 }
10551
VisitCXXConstructExpr(const CXXConstructExpr * E,const LValue & Subobject,APValue * Value,QualType Type)10552 bool ArrayExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E,
10553 const LValue &Subobject,
10554 APValue *Value,
10555 QualType Type) {
10556 bool HadZeroInit = Value->hasValue();
10557
10558 if (const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(Type)) {
10559 unsigned N = CAT->getSize().getZExtValue();
10560
10561 // Preserve the array filler if we had prior zero-initialization.
10562 APValue Filler =
10563 HadZeroInit && Value->hasArrayFiller() ? Value->getArrayFiller()
10564 : APValue();
10565
10566 *Value = APValue(APValue::UninitArray(), N, N);
10567
10568 if (HadZeroInit)
10569 for (unsigned I = 0; I != N; ++I)
10570 Value->getArrayInitializedElt(I) = Filler;
10571
10572 // Initialize the elements.
10573 LValue ArrayElt = Subobject;
10574 ArrayElt.addArray(Info, E, CAT);
10575 for (unsigned I = 0; I != N; ++I)
10576 if (!VisitCXXConstructExpr(E, ArrayElt, &Value->getArrayInitializedElt(I),
10577 CAT->getElementType()) ||
10578 !HandleLValueArrayAdjustment(Info, E, ArrayElt,
10579 CAT->getElementType(), 1))
10580 return false;
10581
10582 return true;
10583 }
10584
10585 if (!Type->isRecordType())
10586 return Error(E);
10587
10588 return RecordExprEvaluator(Info, Subobject, *Value)
10589 .VisitCXXConstructExpr(E, Type);
10590 }
10591
10592 //===----------------------------------------------------------------------===//
10593 // Integer Evaluation
10594 //
10595 // As a GNU extension, we support casting pointers to sufficiently-wide integer
10596 // types and back in constant folding. Integer values are thus represented
10597 // either as an integer-valued APValue, or as an lvalue-valued APValue.
10598 //===----------------------------------------------------------------------===//
10599
10600 namespace {
10601 class IntExprEvaluator
10602 : public ExprEvaluatorBase<IntExprEvaluator> {
10603 APValue &Result;
10604 public:
IntExprEvaluator(EvalInfo & info,APValue & result)10605 IntExprEvaluator(EvalInfo &info, APValue &result)
10606 : ExprEvaluatorBaseTy(info), Result(result) {}
10607
Success(const llvm::APSInt & SI,const Expr * E,APValue & Result)10608 bool Success(const llvm::APSInt &SI, const Expr *E, APValue &Result) {
10609 assert(E->getType()->isIntegralOrEnumerationType() &&
10610 "Invalid evaluation result.");
10611 assert(SI.isSigned() == E->getType()->isSignedIntegerOrEnumerationType() &&
10612 "Invalid evaluation result.");
10613 assert(SI.getBitWidth() == Info.Ctx.getIntWidth(E->getType()) &&
10614 "Invalid evaluation result.");
10615 Result = APValue(SI);
10616 return true;
10617 }
Success(const llvm::APSInt & SI,const Expr * E)10618 bool Success(const llvm::APSInt &SI, const Expr *E) {
10619 return Success(SI, E, Result);
10620 }
10621
Success(const llvm::APInt & I,const Expr * E,APValue & Result)10622 bool Success(const llvm::APInt &I, const Expr *E, APValue &Result) {
10623 assert(E->getType()->isIntegralOrEnumerationType() &&
10624 "Invalid evaluation result.");
10625 assert(I.getBitWidth() == Info.Ctx.getIntWidth(E->getType()) &&
10626 "Invalid evaluation result.");
10627 Result = APValue(APSInt(I));
10628 Result.getInt().setIsUnsigned(
10629 E->getType()->isUnsignedIntegerOrEnumerationType());
10630 return true;
10631 }
Success(const llvm::APInt & I,const Expr * E)10632 bool Success(const llvm::APInt &I, const Expr *E) {
10633 return Success(I, E, Result);
10634 }
10635
Success(uint64_t Value,const Expr * E,APValue & Result)10636 bool Success(uint64_t Value, const Expr *E, APValue &Result) {
10637 assert(E->getType()->isIntegralOrEnumerationType() &&
10638 "Invalid evaluation result.");
10639 Result = APValue(Info.Ctx.MakeIntValue(Value, E->getType()));
10640 return true;
10641 }
Success(uint64_t Value,const Expr * E)10642 bool Success(uint64_t Value, const Expr *E) {
10643 return Success(Value, E, Result);
10644 }
10645
Success(CharUnits Size,const Expr * E)10646 bool Success(CharUnits Size, const Expr *E) {
10647 return Success(Size.getQuantity(), E);
10648 }
10649
Success(const APValue & V,const Expr * E)10650 bool Success(const APValue &V, const Expr *E) {
10651 if (V.isLValue() || V.isAddrLabelDiff() || V.isIndeterminate()) {
10652 Result = V;
10653 return true;
10654 }
10655 return Success(V.getInt(), E);
10656 }
10657
ZeroInitialization(const Expr * E)10658 bool ZeroInitialization(const Expr *E) { return Success(0, E); }
10659
10660 //===--------------------------------------------------------------------===//
10661 // Visitor Methods
10662 //===--------------------------------------------------------------------===//
10663
VisitIntegerLiteral(const IntegerLiteral * E)10664 bool VisitIntegerLiteral(const IntegerLiteral *E) {
10665 return Success(E->getValue(), E);
10666 }
VisitCharacterLiteral(const CharacterLiteral * E)10667 bool VisitCharacterLiteral(const CharacterLiteral *E) {
10668 return Success(E->getValue(), E);
10669 }
10670
10671 bool CheckReferencedDecl(const Expr *E, const Decl *D);
VisitDeclRefExpr(const DeclRefExpr * E)10672 bool VisitDeclRefExpr(const DeclRefExpr *E) {
10673 if (CheckReferencedDecl(E, E->getDecl()))
10674 return true;
10675
10676 return ExprEvaluatorBaseTy::VisitDeclRefExpr(E);
10677 }
VisitMemberExpr(const MemberExpr * E)10678 bool VisitMemberExpr(const MemberExpr *E) {
10679 if (CheckReferencedDecl(E, E->getMemberDecl())) {
10680 VisitIgnoredBaseExpression(E->getBase());
10681 return true;
10682 }
10683
10684 return ExprEvaluatorBaseTy::VisitMemberExpr(E);
10685 }
10686
10687 bool VisitCallExpr(const CallExpr *E);
10688 bool VisitBuiltinCallExpr(const CallExpr *E, unsigned BuiltinOp);
10689 bool VisitBinaryOperator(const BinaryOperator *E);
10690 bool VisitOffsetOfExpr(const OffsetOfExpr *E);
10691 bool VisitUnaryOperator(const UnaryOperator *E);
10692
10693 bool VisitCastExpr(const CastExpr* E);
10694 bool VisitUnaryExprOrTypeTraitExpr(const UnaryExprOrTypeTraitExpr *E);
10695
VisitCXXBoolLiteralExpr(const CXXBoolLiteralExpr * E)10696 bool VisitCXXBoolLiteralExpr(const CXXBoolLiteralExpr *E) {
10697 return Success(E->getValue(), E);
10698 }
10699
VisitObjCBoolLiteralExpr(const ObjCBoolLiteralExpr * E)10700 bool VisitObjCBoolLiteralExpr(const ObjCBoolLiteralExpr *E) {
10701 return Success(E->getValue(), E);
10702 }
10703
VisitArrayInitIndexExpr(const ArrayInitIndexExpr * E)10704 bool VisitArrayInitIndexExpr(const ArrayInitIndexExpr *E) {
10705 if (Info.ArrayInitIndex == uint64_t(-1)) {
10706 // We were asked to evaluate this subexpression independent of the
10707 // enclosing ArrayInitLoopExpr. We can't do that.
10708 Info.FFDiag(E);
10709 return false;
10710 }
10711 return Success(Info.ArrayInitIndex, E);
10712 }
10713
10714 // Note, GNU defines __null as an integer, not a pointer.
VisitGNUNullExpr(const GNUNullExpr * E)10715 bool VisitGNUNullExpr(const GNUNullExpr *E) {
10716 return ZeroInitialization(E);
10717 }
10718
VisitTypeTraitExpr(const TypeTraitExpr * E)10719 bool VisitTypeTraitExpr(const TypeTraitExpr *E) {
10720 return Success(E->getValue(), E);
10721 }
10722
VisitArrayTypeTraitExpr(const ArrayTypeTraitExpr * E)10723 bool VisitArrayTypeTraitExpr(const ArrayTypeTraitExpr *E) {
10724 return Success(E->getValue(), E);
10725 }
10726
VisitExpressionTraitExpr(const ExpressionTraitExpr * E)10727 bool VisitExpressionTraitExpr(const ExpressionTraitExpr *E) {
10728 return Success(E->getValue(), E);
10729 }
10730
10731 bool VisitUnaryReal(const UnaryOperator *E);
10732 bool VisitUnaryImag(const UnaryOperator *E);
10733
10734 bool VisitCXXNoexceptExpr(const CXXNoexceptExpr *E);
10735 bool VisitSizeOfPackExpr(const SizeOfPackExpr *E);
10736 bool VisitSourceLocExpr(const SourceLocExpr *E);
10737 bool VisitConceptSpecializationExpr(const ConceptSpecializationExpr *E);
10738 bool VisitRequiresExpr(const RequiresExpr *E);
10739 // FIXME: Missing: array subscript of vector, member of vector
10740 };
10741
10742 class FixedPointExprEvaluator
10743 : public ExprEvaluatorBase<FixedPointExprEvaluator> {
10744 APValue &Result;
10745
10746 public:
FixedPointExprEvaluator(EvalInfo & info,APValue & result)10747 FixedPointExprEvaluator(EvalInfo &info, APValue &result)
10748 : ExprEvaluatorBaseTy(info), Result(result) {}
10749
Success(const llvm::APInt & I,const Expr * E)10750 bool Success(const llvm::APInt &I, const Expr *E) {
10751 return Success(
10752 APFixedPoint(I, Info.Ctx.getFixedPointSemantics(E->getType())), E);
10753 }
10754
Success(uint64_t Value,const Expr * E)10755 bool Success(uint64_t Value, const Expr *E) {
10756 return Success(
10757 APFixedPoint(Value, Info.Ctx.getFixedPointSemantics(E->getType())), E);
10758 }
10759
Success(const APValue & V,const Expr * E)10760 bool Success(const APValue &V, const Expr *E) {
10761 return Success(V.getFixedPoint(), E);
10762 }
10763
Success(const APFixedPoint & V,const Expr * E)10764 bool Success(const APFixedPoint &V, const Expr *E) {
10765 assert(E->getType()->isFixedPointType() && "Invalid evaluation result.");
10766 assert(V.getWidth() == Info.Ctx.getIntWidth(E->getType()) &&
10767 "Invalid evaluation result.");
10768 Result = APValue(V);
10769 return true;
10770 }
10771
10772 //===--------------------------------------------------------------------===//
10773 // Visitor Methods
10774 //===--------------------------------------------------------------------===//
10775
VisitFixedPointLiteral(const FixedPointLiteral * E)10776 bool VisitFixedPointLiteral(const FixedPointLiteral *E) {
10777 return Success(E->getValue(), E);
10778 }
10779
10780 bool VisitCastExpr(const CastExpr *E);
10781 bool VisitUnaryOperator(const UnaryOperator *E);
10782 bool VisitBinaryOperator(const BinaryOperator *E);
10783 };
10784 } // end anonymous namespace
10785
10786 /// EvaluateIntegerOrLValue - Evaluate an rvalue integral-typed expression, and
10787 /// produce either the integer value or a pointer.
10788 ///
10789 /// GCC has a heinous extension which folds casts between pointer types and
10790 /// pointer-sized integral types. We support this by allowing the evaluation of
10791 /// an integer rvalue to produce a pointer (represented as an lvalue) instead.
10792 /// Some simple arithmetic on such values is supported (they are treated much
10793 /// like char*).
EvaluateIntegerOrLValue(const Expr * E,APValue & Result,EvalInfo & Info)10794 static bool EvaluateIntegerOrLValue(const Expr *E, APValue &Result,
10795 EvalInfo &Info) {
10796 assert(!E->isValueDependent());
10797 assert(E->isRValue() && E->getType()->isIntegralOrEnumerationType());
10798 return IntExprEvaluator(Info, Result).Visit(E);
10799 }
10800
EvaluateInteger(const Expr * E,APSInt & Result,EvalInfo & Info)10801 static bool EvaluateInteger(const Expr *E, APSInt &Result, EvalInfo &Info) {
10802 assert(!E->isValueDependent());
10803 APValue Val;
10804 if (!EvaluateIntegerOrLValue(E, Val, Info))
10805 return false;
10806 if (!Val.isInt()) {
10807 // FIXME: It would be better to produce the diagnostic for casting
10808 // a pointer to an integer.
10809 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
10810 return false;
10811 }
10812 Result = Val.getInt();
10813 return true;
10814 }
10815
VisitSourceLocExpr(const SourceLocExpr * E)10816 bool IntExprEvaluator::VisitSourceLocExpr(const SourceLocExpr *E) {
10817 APValue Evaluated = E->EvaluateInContext(
10818 Info.Ctx, Info.CurrentCall->CurSourceLocExprScope.getDefaultExpr());
10819 return Success(Evaluated, E);
10820 }
10821
EvaluateFixedPoint(const Expr * E,APFixedPoint & Result,EvalInfo & Info)10822 static bool EvaluateFixedPoint(const Expr *E, APFixedPoint &Result,
10823 EvalInfo &Info) {
10824 assert(!E->isValueDependent());
10825 if (E->getType()->isFixedPointType()) {
10826 APValue Val;
10827 if (!FixedPointExprEvaluator(Info, Val).Visit(E))
10828 return false;
10829 if (!Val.isFixedPoint())
10830 return false;
10831
10832 Result = Val.getFixedPoint();
10833 return true;
10834 }
10835 return false;
10836 }
10837
EvaluateFixedPointOrInteger(const Expr * E,APFixedPoint & Result,EvalInfo & Info)10838 static bool EvaluateFixedPointOrInteger(const Expr *E, APFixedPoint &Result,
10839 EvalInfo &Info) {
10840 assert(!E->isValueDependent());
10841 if (E->getType()->isIntegerType()) {
10842 auto FXSema = Info.Ctx.getFixedPointSemantics(E->getType());
10843 APSInt Val;
10844 if (!EvaluateInteger(E, Val, Info))
10845 return false;
10846 Result = APFixedPoint(Val, FXSema);
10847 return true;
10848 } else if (E->getType()->isFixedPointType()) {
10849 return EvaluateFixedPoint(E, Result, Info);
10850 }
10851 return false;
10852 }
10853
10854 /// Check whether the given declaration can be directly converted to an integral
10855 /// rvalue. If not, no diagnostic is produced; there are other things we can
10856 /// try.
CheckReferencedDecl(const Expr * E,const Decl * D)10857 bool IntExprEvaluator::CheckReferencedDecl(const Expr* E, const Decl* D) {
10858 // Enums are integer constant exprs.
10859 if (const EnumConstantDecl *ECD = dyn_cast<EnumConstantDecl>(D)) {
10860 // Check for signedness/width mismatches between E type and ECD value.
10861 bool SameSign = (ECD->getInitVal().isSigned()
10862 == E->getType()->isSignedIntegerOrEnumerationType());
10863 bool SameWidth = (ECD->getInitVal().getBitWidth()
10864 == Info.Ctx.getIntWidth(E->getType()));
10865 if (SameSign && SameWidth)
10866 return Success(ECD->getInitVal(), E);
10867 else {
10868 // Get rid of mismatch (otherwise Success assertions will fail)
10869 // by computing a new value matching the type of E.
10870 llvm::APSInt Val = ECD->getInitVal();
10871 if (!SameSign)
10872 Val.setIsSigned(!ECD->getInitVal().isSigned());
10873 if (!SameWidth)
10874 Val = Val.extOrTrunc(Info.Ctx.getIntWidth(E->getType()));
10875 return Success(Val, E);
10876 }
10877 }
10878 return false;
10879 }
10880
10881 /// Values returned by __builtin_classify_type, chosen to match the values
10882 /// produced by GCC's builtin.
10883 enum class GCCTypeClass {
10884 None = -1,
10885 Void = 0,
10886 Integer = 1,
10887 // GCC reserves 2 for character types, but instead classifies them as
10888 // integers.
10889 Enum = 3,
10890 Bool = 4,
10891 Pointer = 5,
10892 // GCC reserves 6 for references, but appears to never use it (because
10893 // expressions never have reference type, presumably).
10894 PointerToDataMember = 7,
10895 RealFloat = 8,
10896 Complex = 9,
10897 // GCC reserves 10 for functions, but does not use it since GCC version 6 due
10898 // to decay to pointer. (Prior to version 6 it was only used in C++ mode).
10899 // GCC claims to reserve 11 for pointers to member functions, but *actually*
10900 // uses 12 for that purpose, same as for a class or struct. Maybe it
10901 // internally implements a pointer to member as a struct? Who knows.
10902 PointerToMemberFunction = 12, // Not a bug, see above.
10903 ClassOrStruct = 12,
10904 Union = 13,
10905 // GCC reserves 14 for arrays, but does not use it since GCC version 6 due to
10906 // decay to pointer. (Prior to version 6 it was only used in C++ mode).
10907 // GCC reserves 15 for strings, but actually uses 5 (pointer) for string
10908 // literals.
10909 };
10910
10911 /// EvaluateBuiltinClassifyType - Evaluate __builtin_classify_type the same way
10912 /// as GCC.
10913 static GCCTypeClass
EvaluateBuiltinClassifyType(QualType T,const LangOptions & LangOpts)10914 EvaluateBuiltinClassifyType(QualType T, const LangOptions &LangOpts) {
10915 assert(!T->isDependentType() && "unexpected dependent type");
10916
10917 QualType CanTy = T.getCanonicalType();
10918 const BuiltinType *BT = dyn_cast<BuiltinType>(CanTy);
10919
10920 switch (CanTy->getTypeClass()) {
10921 #define TYPE(ID, BASE)
10922 #define DEPENDENT_TYPE(ID, BASE) case Type::ID:
10923 #define NON_CANONICAL_TYPE(ID, BASE) case Type::ID:
10924 #define NON_CANONICAL_UNLESS_DEPENDENT_TYPE(ID, BASE) case Type::ID:
10925 #include "clang/AST/TypeNodes.inc"
10926 case Type::Auto:
10927 case Type::DeducedTemplateSpecialization:
10928 llvm_unreachable("unexpected non-canonical or dependent type");
10929
10930 case Type::Builtin:
10931 switch (BT->getKind()) {
10932 #define BUILTIN_TYPE(ID, SINGLETON_ID)
10933 #define SIGNED_TYPE(ID, SINGLETON_ID) \
10934 case BuiltinType::ID: return GCCTypeClass::Integer;
10935 #define FLOATING_TYPE(ID, SINGLETON_ID) \
10936 case BuiltinType::ID: return GCCTypeClass::RealFloat;
10937 #define PLACEHOLDER_TYPE(ID, SINGLETON_ID) \
10938 case BuiltinType::ID: break;
10939 #include "clang/AST/BuiltinTypes.def"
10940 case BuiltinType::Void:
10941 return GCCTypeClass::Void;
10942
10943 case BuiltinType::Bool:
10944 return GCCTypeClass::Bool;
10945
10946 case BuiltinType::Char_U:
10947 case BuiltinType::UChar:
10948 case BuiltinType::WChar_U:
10949 case BuiltinType::Char8:
10950 case BuiltinType::Char16:
10951 case BuiltinType::Char32:
10952 case BuiltinType::UShort:
10953 case BuiltinType::UInt:
10954 case BuiltinType::ULong:
10955 case BuiltinType::ULongLong:
10956 case BuiltinType::UInt128:
10957 return GCCTypeClass::Integer;
10958
10959 case BuiltinType::UShortAccum:
10960 case BuiltinType::UAccum:
10961 case BuiltinType::ULongAccum:
10962 case BuiltinType::UShortFract:
10963 case BuiltinType::UFract:
10964 case BuiltinType::ULongFract:
10965 case BuiltinType::SatUShortAccum:
10966 case BuiltinType::SatUAccum:
10967 case BuiltinType::SatULongAccum:
10968 case BuiltinType::SatUShortFract:
10969 case BuiltinType::SatUFract:
10970 case BuiltinType::SatULongFract:
10971 return GCCTypeClass::None;
10972
10973 case BuiltinType::NullPtr:
10974
10975 case BuiltinType::ObjCId:
10976 case BuiltinType::ObjCClass:
10977 case BuiltinType::ObjCSel:
10978 #define IMAGE_TYPE(ImgType, Id, SingletonId, Access, Suffix) \
10979 case BuiltinType::Id:
10980 #include "clang/Basic/OpenCLImageTypes.def"
10981 #define EXT_OPAQUE_TYPE(ExtType, Id, Ext) \
10982 case BuiltinType::Id:
10983 #include "clang/Basic/OpenCLExtensionTypes.def"
10984 case BuiltinType::OCLSampler:
10985 case BuiltinType::OCLEvent:
10986 case BuiltinType::OCLClkEvent:
10987 case BuiltinType::OCLQueue:
10988 case BuiltinType::OCLReserveID:
10989 #define SVE_TYPE(Name, Id, SingletonId) \
10990 case BuiltinType::Id:
10991 #include "clang/Basic/AArch64SVEACLETypes.def"
10992 #define PPC_VECTOR_TYPE(Name, Id, Size) \
10993 case BuiltinType::Id:
10994 #include "clang/Basic/PPCTypes.def"
10995 #define RVV_TYPE(Name, Id, SingletonId) case BuiltinType::Id:
10996 #include "clang/Basic/RISCVVTypes.def"
10997 return GCCTypeClass::None;
10998
10999 case BuiltinType::Dependent:
11000 llvm_unreachable("unexpected dependent type");
11001 };
11002 llvm_unreachable("unexpected placeholder type");
11003
11004 case Type::Enum:
11005 return LangOpts.CPlusPlus ? GCCTypeClass::Enum : GCCTypeClass::Integer;
11006
11007 case Type::Pointer:
11008 case Type::ConstantArray:
11009 case Type::VariableArray:
11010 case Type::IncompleteArray:
11011 case Type::FunctionNoProto:
11012 case Type::FunctionProto:
11013 return GCCTypeClass::Pointer;
11014
11015 case Type::MemberPointer:
11016 return CanTy->isMemberDataPointerType()
11017 ? GCCTypeClass::PointerToDataMember
11018 : GCCTypeClass::PointerToMemberFunction;
11019
11020 case Type::Complex:
11021 return GCCTypeClass::Complex;
11022
11023 case Type::Record:
11024 return CanTy->isUnionType() ? GCCTypeClass::Union
11025 : GCCTypeClass::ClassOrStruct;
11026
11027 case Type::Atomic:
11028 // GCC classifies _Atomic T the same as T.
11029 return EvaluateBuiltinClassifyType(
11030 CanTy->castAs<AtomicType>()->getValueType(), LangOpts);
11031
11032 case Type::BlockPointer:
11033 case Type::Vector:
11034 case Type::ExtVector:
11035 case Type::ConstantMatrix:
11036 case Type::ObjCObject:
11037 case Type::ObjCInterface:
11038 case Type::ObjCObjectPointer:
11039 case Type::Pipe:
11040 case Type::ExtInt:
11041 // GCC classifies vectors as None. We follow its lead and classify all
11042 // other types that don't fit into the regular classification the same way.
11043 return GCCTypeClass::None;
11044
11045 case Type::LValueReference:
11046 case Type::RValueReference:
11047 llvm_unreachable("invalid type for expression");
11048 }
11049
11050 llvm_unreachable("unexpected type class");
11051 }
11052
11053 /// EvaluateBuiltinClassifyType - Evaluate __builtin_classify_type the same way
11054 /// as GCC.
11055 static GCCTypeClass
EvaluateBuiltinClassifyType(const CallExpr * E,const LangOptions & LangOpts)11056 EvaluateBuiltinClassifyType(const CallExpr *E, const LangOptions &LangOpts) {
11057 // If no argument was supplied, default to None. This isn't
11058 // ideal, however it is what gcc does.
11059 if (E->getNumArgs() == 0)
11060 return GCCTypeClass::None;
11061
11062 // FIXME: Bizarrely, GCC treats a call with more than one argument as not
11063 // being an ICE, but still folds it to a constant using the type of the first
11064 // argument.
11065 return EvaluateBuiltinClassifyType(E->getArg(0)->getType(), LangOpts);
11066 }
11067
11068 /// EvaluateBuiltinConstantPForLValue - Determine the result of
11069 /// __builtin_constant_p when applied to the given pointer.
11070 ///
11071 /// A pointer is only "constant" if it is null (or a pointer cast to integer)
11072 /// or it points to the first character of a string literal.
EvaluateBuiltinConstantPForLValue(const APValue & LV)11073 static bool EvaluateBuiltinConstantPForLValue(const APValue &LV) {
11074 APValue::LValueBase Base = LV.getLValueBase();
11075 if (Base.isNull()) {
11076 // A null base is acceptable.
11077 return true;
11078 } else if (const Expr *E = Base.dyn_cast<const Expr *>()) {
11079 if (!isa<StringLiteral>(E))
11080 return false;
11081 return LV.getLValueOffset().isZero();
11082 } else if (Base.is<TypeInfoLValue>()) {
11083 // Surprisingly, GCC considers __builtin_constant_p(&typeid(int)) to
11084 // evaluate to true.
11085 return true;
11086 } else {
11087 // Any other base is not constant enough for GCC.
11088 return false;
11089 }
11090 }
11091
11092 /// EvaluateBuiltinConstantP - Evaluate __builtin_constant_p as similarly to
11093 /// GCC as we can manage.
EvaluateBuiltinConstantP(EvalInfo & Info,const Expr * Arg)11094 static bool EvaluateBuiltinConstantP(EvalInfo &Info, const Expr *Arg) {
11095 // This evaluation is not permitted to have side-effects, so evaluate it in
11096 // a speculative evaluation context.
11097 SpeculativeEvaluationRAII SpeculativeEval(Info);
11098
11099 // Constant-folding is always enabled for the operand of __builtin_constant_p
11100 // (even when the enclosing evaluation context otherwise requires a strict
11101 // language-specific constant expression).
11102 FoldConstant Fold(Info, true);
11103
11104 QualType ArgType = Arg->getType();
11105
11106 // __builtin_constant_p always has one operand. The rules which gcc follows
11107 // are not precisely documented, but are as follows:
11108 //
11109 // - If the operand is of integral, floating, complex or enumeration type,
11110 // and can be folded to a known value of that type, it returns 1.
11111 // - If the operand can be folded to a pointer to the first character
11112 // of a string literal (or such a pointer cast to an integral type)
11113 // or to a null pointer or an integer cast to a pointer, it returns 1.
11114 //
11115 // Otherwise, it returns 0.
11116 //
11117 // FIXME: GCC also intends to return 1 for literals of aggregate types, but
11118 // its support for this did not work prior to GCC 9 and is not yet well
11119 // understood.
11120 if (ArgType->isIntegralOrEnumerationType() || ArgType->isFloatingType() ||
11121 ArgType->isAnyComplexType() || ArgType->isPointerType() ||
11122 ArgType->isNullPtrType()) {
11123 APValue V;
11124 if (!::EvaluateAsRValue(Info, Arg, V) || Info.EvalStatus.HasSideEffects) {
11125 Fold.keepDiagnostics();
11126 return false;
11127 }
11128
11129 // For a pointer (possibly cast to integer), there are special rules.
11130 if (V.getKind() == APValue::LValue)
11131 return EvaluateBuiltinConstantPForLValue(V);
11132
11133 // Otherwise, any constant value is good enough.
11134 return V.hasValue();
11135 }
11136
11137 // Anything else isn't considered to be sufficiently constant.
11138 return false;
11139 }
11140
11141 /// Retrieves the "underlying object type" of the given expression,
11142 /// as used by __builtin_object_size.
getObjectType(APValue::LValueBase B)11143 static QualType getObjectType(APValue::LValueBase B) {
11144 if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) {
11145 if (const VarDecl *VD = dyn_cast<VarDecl>(D))
11146 return VD->getType();
11147 } else if (const Expr *E = B.dyn_cast<const Expr*>()) {
11148 if (isa<CompoundLiteralExpr>(E))
11149 return E->getType();
11150 } else if (B.is<TypeInfoLValue>()) {
11151 return B.getTypeInfoType();
11152 } else if (B.is<DynamicAllocLValue>()) {
11153 return B.getDynamicAllocType();
11154 }
11155
11156 return QualType();
11157 }
11158
11159 /// A more selective version of E->IgnoreParenCasts for
11160 /// tryEvaluateBuiltinObjectSize. This ignores some casts/parens that serve only
11161 /// to change the type of E.
11162 /// Ex. For E = `(short*)((char*)(&foo))`, returns `&foo`
11163 ///
11164 /// Always returns an RValue with a pointer representation.
ignorePointerCastsAndParens(const Expr * E)11165 static const Expr *ignorePointerCastsAndParens(const Expr *E) {
11166 assert(E->isRValue() && E->getType()->hasPointerRepresentation());
11167
11168 auto *NoParens = E->IgnoreParens();
11169 auto *Cast = dyn_cast<CastExpr>(NoParens);
11170 if (Cast == nullptr)
11171 return NoParens;
11172
11173 // We only conservatively allow a few kinds of casts, because this code is
11174 // inherently a simple solution that seeks to support the common case.
11175 auto CastKind = Cast->getCastKind();
11176 if (CastKind != CK_NoOp && CastKind != CK_BitCast &&
11177 CastKind != CK_AddressSpaceConversion)
11178 return NoParens;
11179
11180 auto *SubExpr = Cast->getSubExpr();
11181 if (!SubExpr->getType()->hasPointerRepresentation() || !SubExpr->isRValue())
11182 return NoParens;
11183 return ignorePointerCastsAndParens(SubExpr);
11184 }
11185
11186 /// Checks to see if the given LValue's Designator is at the end of the LValue's
11187 /// record layout. e.g.
11188 /// struct { struct { int a, b; } fst, snd; } obj;
11189 /// obj.fst // no
11190 /// obj.snd // yes
11191 /// obj.fst.a // no
11192 /// obj.fst.b // no
11193 /// obj.snd.a // no
11194 /// obj.snd.b // yes
11195 ///
11196 /// Please note: this function is specialized for how __builtin_object_size
11197 /// views "objects".
11198 ///
11199 /// If this encounters an invalid RecordDecl or otherwise cannot determine the
11200 /// correct result, it will always return true.
isDesignatorAtObjectEnd(const ASTContext & Ctx,const LValue & LVal)11201 static bool isDesignatorAtObjectEnd(const ASTContext &Ctx, const LValue &LVal) {
11202 assert(!LVal.Designator.Invalid);
11203
11204 auto IsLastOrInvalidFieldDecl = [&Ctx](const FieldDecl *FD, bool &Invalid) {
11205 const RecordDecl *Parent = FD->getParent();
11206 Invalid = Parent->isInvalidDecl();
11207 if (Invalid || Parent->isUnion())
11208 return true;
11209 const ASTRecordLayout &Layout = Ctx.getASTRecordLayout(Parent);
11210 return FD->getFieldIndex() + 1 == Layout.getFieldCount();
11211 };
11212
11213 auto &Base = LVal.getLValueBase();
11214 if (auto *ME = dyn_cast_or_null<MemberExpr>(Base.dyn_cast<const Expr *>())) {
11215 if (auto *FD = dyn_cast<FieldDecl>(ME->getMemberDecl())) {
11216 bool Invalid;
11217 if (!IsLastOrInvalidFieldDecl(FD, Invalid))
11218 return Invalid;
11219 } else if (auto *IFD = dyn_cast<IndirectFieldDecl>(ME->getMemberDecl())) {
11220 for (auto *FD : IFD->chain()) {
11221 bool Invalid;
11222 if (!IsLastOrInvalidFieldDecl(cast<FieldDecl>(FD), Invalid))
11223 return Invalid;
11224 }
11225 }
11226 }
11227
11228 unsigned I = 0;
11229 QualType BaseType = getType(Base);
11230 if (LVal.Designator.FirstEntryIsAnUnsizedArray) {
11231 // If we don't know the array bound, conservatively assume we're looking at
11232 // the final array element.
11233 ++I;
11234 if (BaseType->isIncompleteArrayType())
11235 BaseType = Ctx.getAsArrayType(BaseType)->getElementType();
11236 else
11237 BaseType = BaseType->castAs<PointerType>()->getPointeeType();
11238 }
11239
11240 for (unsigned E = LVal.Designator.Entries.size(); I != E; ++I) {
11241 const auto &Entry = LVal.Designator.Entries[I];
11242 if (BaseType->isArrayType()) {
11243 // Because __builtin_object_size treats arrays as objects, we can ignore
11244 // the index iff this is the last array in the Designator.
11245 if (I + 1 == E)
11246 return true;
11247 const auto *CAT = cast<ConstantArrayType>(Ctx.getAsArrayType(BaseType));
11248 uint64_t Index = Entry.getAsArrayIndex();
11249 if (Index + 1 != CAT->getSize())
11250 return false;
11251 BaseType = CAT->getElementType();
11252 } else if (BaseType->isAnyComplexType()) {
11253 const auto *CT = BaseType->castAs<ComplexType>();
11254 uint64_t Index = Entry.getAsArrayIndex();
11255 if (Index != 1)
11256 return false;
11257 BaseType = CT->getElementType();
11258 } else if (auto *FD = getAsField(Entry)) {
11259 bool Invalid;
11260 if (!IsLastOrInvalidFieldDecl(FD, Invalid))
11261 return Invalid;
11262 BaseType = FD->getType();
11263 } else {
11264 assert(getAsBaseClass(Entry) && "Expecting cast to a base class");
11265 return false;
11266 }
11267 }
11268 return true;
11269 }
11270
11271 /// Tests to see if the LValue has a user-specified designator (that isn't
11272 /// necessarily valid). Note that this always returns 'true' if the LValue has
11273 /// an unsized array as its first designator entry, because there's currently no
11274 /// way to tell if the user typed *foo or foo[0].
refersToCompleteObject(const LValue & LVal)11275 static bool refersToCompleteObject(const LValue &LVal) {
11276 if (LVal.Designator.Invalid)
11277 return false;
11278
11279 if (!LVal.Designator.Entries.empty())
11280 return LVal.Designator.isMostDerivedAnUnsizedArray();
11281
11282 if (!LVal.InvalidBase)
11283 return true;
11284
11285 // If `E` is a MemberExpr, then the first part of the designator is hiding in
11286 // the LValueBase.
11287 const auto *E = LVal.Base.dyn_cast<const Expr *>();
11288 return !E || !isa<MemberExpr>(E);
11289 }
11290
11291 /// Attempts to detect a user writing into a piece of memory that's impossible
11292 /// to figure out the size of by just using types.
isUserWritingOffTheEnd(const ASTContext & Ctx,const LValue & LVal)11293 static bool isUserWritingOffTheEnd(const ASTContext &Ctx, const LValue &LVal) {
11294 const SubobjectDesignator &Designator = LVal.Designator;
11295 // Notes:
11296 // - Users can only write off of the end when we have an invalid base. Invalid
11297 // bases imply we don't know where the memory came from.
11298 // - We used to be a bit more aggressive here; we'd only be conservative if
11299 // the array at the end was flexible, or if it had 0 or 1 elements. This
11300 // broke some common standard library extensions (PR30346), but was
11301 // otherwise seemingly fine. It may be useful to reintroduce this behavior
11302 // with some sort of list. OTOH, it seems that GCC is always
11303 // conservative with the last element in structs (if it's an array), so our
11304 // current behavior is more compatible than an explicit list approach would
11305 // be.
11306 return LVal.InvalidBase &&
11307 Designator.Entries.size() == Designator.MostDerivedPathLength &&
11308 Designator.MostDerivedIsArrayElement &&
11309 isDesignatorAtObjectEnd(Ctx, LVal);
11310 }
11311
11312 /// Converts the given APInt to CharUnits, assuming the APInt is unsigned.
11313 /// Fails if the conversion would cause loss of precision.
convertUnsignedAPIntToCharUnits(const llvm::APInt & Int,CharUnits & Result)11314 static bool convertUnsignedAPIntToCharUnits(const llvm::APInt &Int,
11315 CharUnits &Result) {
11316 auto CharUnitsMax = std::numeric_limits<CharUnits::QuantityType>::max();
11317 if (Int.ugt(CharUnitsMax))
11318 return false;
11319 Result = CharUnits::fromQuantity(Int.getZExtValue());
11320 return true;
11321 }
11322
11323 /// Helper for tryEvaluateBuiltinObjectSize -- Given an LValue, this will
11324 /// determine how many bytes exist from the beginning of the object to either
11325 /// the end of the current subobject, or the end of the object itself, depending
11326 /// on what the LValue looks like + the value of Type.
11327 ///
11328 /// If this returns false, the value of Result is undefined.
determineEndOffset(EvalInfo & Info,SourceLocation ExprLoc,unsigned Type,const LValue & LVal,CharUnits & EndOffset)11329 static bool determineEndOffset(EvalInfo &Info, SourceLocation ExprLoc,
11330 unsigned Type, const LValue &LVal,
11331 CharUnits &EndOffset) {
11332 bool DetermineForCompleteObject = refersToCompleteObject(LVal);
11333
11334 auto CheckedHandleSizeof = [&](QualType Ty, CharUnits &Result) {
11335 if (Ty.isNull() || Ty->isIncompleteType() || Ty->isFunctionType())
11336 return false;
11337 return HandleSizeof(Info, ExprLoc, Ty, Result);
11338 };
11339
11340 // We want to evaluate the size of the entire object. This is a valid fallback
11341 // for when Type=1 and the designator is invalid, because we're asked for an
11342 // upper-bound.
11343 if (!(Type & 1) || LVal.Designator.Invalid || DetermineForCompleteObject) {
11344 // Type=3 wants a lower bound, so we can't fall back to this.
11345 if (Type == 3 && !DetermineForCompleteObject)
11346 return false;
11347
11348 llvm::APInt APEndOffset;
11349 if (isBaseAnAllocSizeCall(LVal.getLValueBase()) &&
11350 getBytesReturnedByAllocSizeCall(Info.Ctx, LVal, APEndOffset))
11351 return convertUnsignedAPIntToCharUnits(APEndOffset, EndOffset);
11352
11353 if (LVal.InvalidBase)
11354 return false;
11355
11356 QualType BaseTy = getObjectType(LVal.getLValueBase());
11357 return CheckedHandleSizeof(BaseTy, EndOffset);
11358 }
11359
11360 // We want to evaluate the size of a subobject.
11361 const SubobjectDesignator &Designator = LVal.Designator;
11362
11363 // The following is a moderately common idiom in C:
11364 //
11365 // struct Foo { int a; char c[1]; };
11366 // struct Foo *F = (struct Foo *)malloc(sizeof(struct Foo) + strlen(Bar));
11367 // strcpy(&F->c[0], Bar);
11368 //
11369 // In order to not break too much legacy code, we need to support it.
11370 if (isUserWritingOffTheEnd(Info.Ctx, LVal)) {
11371 // If we can resolve this to an alloc_size call, we can hand that back,
11372 // because we know for certain how many bytes there are to write to.
11373 llvm::APInt APEndOffset;
11374 if (isBaseAnAllocSizeCall(LVal.getLValueBase()) &&
11375 getBytesReturnedByAllocSizeCall(Info.Ctx, LVal, APEndOffset))
11376 return convertUnsignedAPIntToCharUnits(APEndOffset, EndOffset);
11377
11378 // If we cannot determine the size of the initial allocation, then we can't
11379 // given an accurate upper-bound. However, we are still able to give
11380 // conservative lower-bounds for Type=3.
11381 if (Type == 1)
11382 return false;
11383 }
11384
11385 CharUnits BytesPerElem;
11386 if (!CheckedHandleSizeof(Designator.MostDerivedType, BytesPerElem))
11387 return false;
11388
11389 // According to the GCC documentation, we want the size of the subobject
11390 // denoted by the pointer. But that's not quite right -- what we actually
11391 // want is the size of the immediately-enclosing array, if there is one.
11392 int64_t ElemsRemaining;
11393 if (Designator.MostDerivedIsArrayElement &&
11394 Designator.Entries.size() == Designator.MostDerivedPathLength) {
11395 uint64_t ArraySize = Designator.getMostDerivedArraySize();
11396 uint64_t ArrayIndex = Designator.Entries.back().getAsArrayIndex();
11397 ElemsRemaining = ArraySize <= ArrayIndex ? 0 : ArraySize - ArrayIndex;
11398 } else {
11399 ElemsRemaining = Designator.isOnePastTheEnd() ? 0 : 1;
11400 }
11401
11402 EndOffset = LVal.getLValueOffset() + BytesPerElem * ElemsRemaining;
11403 return true;
11404 }
11405
11406 /// Tries to evaluate the __builtin_object_size for @p E. If successful,
11407 /// returns true and stores the result in @p Size.
11408 ///
11409 /// If @p WasError is non-null, this will report whether the failure to evaluate
11410 /// is to be treated as an Error in IntExprEvaluator.
tryEvaluateBuiltinObjectSize(const Expr * E,unsigned Type,EvalInfo & Info,uint64_t & Size)11411 static bool tryEvaluateBuiltinObjectSize(const Expr *E, unsigned Type,
11412 EvalInfo &Info, uint64_t &Size) {
11413 // Determine the denoted object.
11414 LValue LVal;
11415 {
11416 // The operand of __builtin_object_size is never evaluated for side-effects.
11417 // If there are any, but we can determine the pointed-to object anyway, then
11418 // ignore the side-effects.
11419 SpeculativeEvaluationRAII SpeculativeEval(Info);
11420 IgnoreSideEffectsRAII Fold(Info);
11421
11422 if (E->isGLValue()) {
11423 // It's possible for us to be given GLValues if we're called via
11424 // Expr::tryEvaluateObjectSize.
11425 APValue RVal;
11426 if (!EvaluateAsRValue(Info, E, RVal))
11427 return false;
11428 LVal.setFrom(Info.Ctx, RVal);
11429 } else if (!EvaluatePointer(ignorePointerCastsAndParens(E), LVal, Info,
11430 /*InvalidBaseOK=*/true))
11431 return false;
11432 }
11433
11434 // If we point to before the start of the object, there are no accessible
11435 // bytes.
11436 if (LVal.getLValueOffset().isNegative()) {
11437 Size = 0;
11438 return true;
11439 }
11440
11441 CharUnits EndOffset;
11442 if (!determineEndOffset(Info, E->getExprLoc(), Type, LVal, EndOffset))
11443 return false;
11444
11445 // If we've fallen outside of the end offset, just pretend there's nothing to
11446 // write to/read from.
11447 if (EndOffset <= LVal.getLValueOffset())
11448 Size = 0;
11449 else
11450 Size = (EndOffset - LVal.getLValueOffset()).getQuantity();
11451 return true;
11452 }
11453
VisitCallExpr(const CallExpr * E)11454 bool IntExprEvaluator::VisitCallExpr(const CallExpr *E) {
11455 if (unsigned BuiltinOp = E->getBuiltinCallee())
11456 return VisitBuiltinCallExpr(E, BuiltinOp);
11457
11458 return ExprEvaluatorBaseTy::VisitCallExpr(E);
11459 }
11460
getBuiltinAlignArguments(const CallExpr * E,EvalInfo & Info,APValue & Val,APSInt & Alignment)11461 static bool getBuiltinAlignArguments(const CallExpr *E, EvalInfo &Info,
11462 APValue &Val, APSInt &Alignment) {
11463 QualType SrcTy = E->getArg(0)->getType();
11464 if (!getAlignmentArgument(E->getArg(1), SrcTy, Info, Alignment))
11465 return false;
11466 // Even though we are evaluating integer expressions we could get a pointer
11467 // argument for the __builtin_is_aligned() case.
11468 if (SrcTy->isPointerType()) {
11469 LValue Ptr;
11470 if (!EvaluatePointer(E->getArg(0), Ptr, Info))
11471 return false;
11472 Ptr.moveInto(Val);
11473 } else if (!SrcTy->isIntegralOrEnumerationType()) {
11474 Info.FFDiag(E->getArg(0));
11475 return false;
11476 } else {
11477 APSInt SrcInt;
11478 if (!EvaluateInteger(E->getArg(0), SrcInt, Info))
11479 return false;
11480 assert(SrcInt.getBitWidth() >= Alignment.getBitWidth() &&
11481 "Bit widths must be the same");
11482 Val = APValue(SrcInt);
11483 }
11484 assert(Val.hasValue());
11485 return true;
11486 }
11487
VisitBuiltinCallExpr(const CallExpr * E,unsigned BuiltinOp)11488 bool IntExprEvaluator::VisitBuiltinCallExpr(const CallExpr *E,
11489 unsigned BuiltinOp) {
11490 switch (BuiltinOp) {
11491 default:
11492 return ExprEvaluatorBaseTy::VisitCallExpr(E);
11493
11494 case Builtin::BI__builtin_dynamic_object_size:
11495 case Builtin::BI__builtin_object_size: {
11496 // The type was checked when we built the expression.
11497 unsigned Type =
11498 E->getArg(1)->EvaluateKnownConstInt(Info.Ctx).getZExtValue();
11499 assert(Type <= 3 && "unexpected type");
11500
11501 uint64_t Size;
11502 if (tryEvaluateBuiltinObjectSize(E->getArg(0), Type, Info, Size))
11503 return Success(Size, E);
11504
11505 if (E->getArg(0)->HasSideEffects(Info.Ctx))
11506 return Success((Type & 2) ? 0 : -1, E);
11507
11508 // Expression had no side effects, but we couldn't statically determine the
11509 // size of the referenced object.
11510 switch (Info.EvalMode) {
11511 case EvalInfo::EM_ConstantExpression:
11512 case EvalInfo::EM_ConstantFold:
11513 case EvalInfo::EM_IgnoreSideEffects:
11514 // Leave it to IR generation.
11515 return Error(E);
11516 case EvalInfo::EM_ConstantExpressionUnevaluated:
11517 // Reduce it to a constant now.
11518 return Success((Type & 2) ? 0 : -1, E);
11519 }
11520
11521 llvm_unreachable("unexpected EvalMode");
11522 }
11523
11524 case Builtin::BI__builtin_os_log_format_buffer_size: {
11525 analyze_os_log::OSLogBufferLayout Layout;
11526 analyze_os_log::computeOSLogBufferLayout(Info.Ctx, E, Layout);
11527 return Success(Layout.size().getQuantity(), E);
11528 }
11529
11530 case Builtin::BI__builtin_is_aligned: {
11531 APValue Src;
11532 APSInt Alignment;
11533 if (!getBuiltinAlignArguments(E, Info, Src, Alignment))
11534 return false;
11535 if (Src.isLValue()) {
11536 // If we evaluated a pointer, check the minimum known alignment.
11537 LValue Ptr;
11538 Ptr.setFrom(Info.Ctx, Src);
11539 CharUnits BaseAlignment = getBaseAlignment(Info, Ptr);
11540 CharUnits PtrAlign = BaseAlignment.alignmentAtOffset(Ptr.Offset);
11541 // We can return true if the known alignment at the computed offset is
11542 // greater than the requested alignment.
11543 assert(PtrAlign.isPowerOfTwo());
11544 assert(Alignment.isPowerOf2());
11545 if (PtrAlign.getQuantity() >= Alignment)
11546 return Success(1, E);
11547 // If the alignment is not known to be sufficient, some cases could still
11548 // be aligned at run time. However, if the requested alignment is less or
11549 // equal to the base alignment and the offset is not aligned, we know that
11550 // the run-time value can never be aligned.
11551 if (BaseAlignment.getQuantity() >= Alignment &&
11552 PtrAlign.getQuantity() < Alignment)
11553 return Success(0, E);
11554 // Otherwise we can't infer whether the value is sufficiently aligned.
11555 // TODO: __builtin_is_aligned(__builtin_align_{down,up{(expr, N), N)
11556 // in cases where we can't fully evaluate the pointer.
11557 Info.FFDiag(E->getArg(0), diag::note_constexpr_alignment_compute)
11558 << Alignment;
11559 return false;
11560 }
11561 assert(Src.isInt());
11562 return Success((Src.getInt() & (Alignment - 1)) == 0 ? 1 : 0, E);
11563 }
11564 case Builtin::BI__builtin_align_up: {
11565 APValue Src;
11566 APSInt Alignment;
11567 if (!getBuiltinAlignArguments(E, Info, Src, Alignment))
11568 return false;
11569 if (!Src.isInt())
11570 return Error(E);
11571 APSInt AlignedVal =
11572 APSInt((Src.getInt() + (Alignment - 1)) & ~(Alignment - 1),
11573 Src.getInt().isUnsigned());
11574 assert(AlignedVal.getBitWidth() == Src.getInt().getBitWidth());
11575 return Success(AlignedVal, E);
11576 }
11577 case Builtin::BI__builtin_align_down: {
11578 APValue Src;
11579 APSInt Alignment;
11580 if (!getBuiltinAlignArguments(E, Info, Src, Alignment))
11581 return false;
11582 if (!Src.isInt())
11583 return Error(E);
11584 APSInt AlignedVal =
11585 APSInt(Src.getInt() & ~(Alignment - 1), Src.getInt().isUnsigned());
11586 assert(AlignedVal.getBitWidth() == Src.getInt().getBitWidth());
11587 return Success(AlignedVal, E);
11588 }
11589
11590 case Builtin::BI__builtin_bitreverse8:
11591 case Builtin::BI__builtin_bitreverse16:
11592 case Builtin::BI__builtin_bitreverse32:
11593 case Builtin::BI__builtin_bitreverse64: {
11594 APSInt Val;
11595 if (!EvaluateInteger(E->getArg(0), Val, Info))
11596 return false;
11597
11598 return Success(Val.reverseBits(), E);
11599 }
11600
11601 case Builtin::BI__builtin_bswap16:
11602 case Builtin::BI__builtin_bswap32:
11603 case Builtin::BI__builtin_bswap64: {
11604 APSInt Val;
11605 if (!EvaluateInteger(E->getArg(0), Val, Info))
11606 return false;
11607
11608 return Success(Val.byteSwap(), E);
11609 }
11610
11611 case Builtin::BI__builtin_classify_type:
11612 return Success((int)EvaluateBuiltinClassifyType(E, Info.getLangOpts()), E);
11613
11614 case Builtin::BI__builtin_clrsb:
11615 case Builtin::BI__builtin_clrsbl:
11616 case Builtin::BI__builtin_clrsbll: {
11617 APSInt Val;
11618 if (!EvaluateInteger(E->getArg(0), Val, Info))
11619 return false;
11620
11621 return Success(Val.getBitWidth() - Val.getMinSignedBits(), E);
11622 }
11623
11624 case Builtin::BI__builtin_clz:
11625 case Builtin::BI__builtin_clzl:
11626 case Builtin::BI__builtin_clzll:
11627 case Builtin::BI__builtin_clzs: {
11628 APSInt Val;
11629 if (!EvaluateInteger(E->getArg(0), Val, Info))
11630 return false;
11631 if (!Val)
11632 return Error(E);
11633
11634 return Success(Val.countLeadingZeros(), E);
11635 }
11636
11637 case Builtin::BI__builtin_constant_p: {
11638 const Expr *Arg = E->getArg(0);
11639 if (EvaluateBuiltinConstantP(Info, Arg))
11640 return Success(true, E);
11641 if (Info.InConstantContext || Arg->HasSideEffects(Info.Ctx)) {
11642 // Outside a constant context, eagerly evaluate to false in the presence
11643 // of side-effects in order to avoid -Wunsequenced false-positives in
11644 // a branch on __builtin_constant_p(expr).
11645 return Success(false, E);
11646 }
11647 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
11648 return false;
11649 }
11650
11651 case Builtin::BI__builtin_is_constant_evaluated: {
11652 const auto *Callee = Info.CurrentCall->getCallee();
11653 if (Info.InConstantContext && !Info.CheckingPotentialConstantExpression &&
11654 (Info.CallStackDepth == 1 ||
11655 (Info.CallStackDepth == 2 && Callee->isInStdNamespace() &&
11656 Callee->getIdentifier() &&
11657 Callee->getIdentifier()->isStr("is_constant_evaluated")))) {
11658 // FIXME: Find a better way to avoid duplicated diagnostics.
11659 if (Info.EvalStatus.Diag)
11660 Info.report((Info.CallStackDepth == 1) ? E->getExprLoc()
11661 : Info.CurrentCall->CallLoc,
11662 diag::warn_is_constant_evaluated_always_true_constexpr)
11663 << (Info.CallStackDepth == 1 ? "__builtin_is_constant_evaluated"
11664 : "std::is_constant_evaluated");
11665 }
11666
11667 return Success(Info.InConstantContext, E);
11668 }
11669
11670 case Builtin::BI__builtin_ctz:
11671 case Builtin::BI__builtin_ctzl:
11672 case Builtin::BI__builtin_ctzll:
11673 case Builtin::BI__builtin_ctzs: {
11674 APSInt Val;
11675 if (!EvaluateInteger(E->getArg(0), Val, Info))
11676 return false;
11677 if (!Val)
11678 return Error(E);
11679
11680 return Success(Val.countTrailingZeros(), E);
11681 }
11682
11683 case Builtin::BI__builtin_eh_return_data_regno: {
11684 int Operand = E->getArg(0)->EvaluateKnownConstInt(Info.Ctx).getZExtValue();
11685 Operand = Info.Ctx.getTargetInfo().getEHDataRegisterNumber(Operand);
11686 return Success(Operand, E);
11687 }
11688
11689 case Builtin::BI__builtin_expect:
11690 case Builtin::BI__builtin_expect_with_probability:
11691 return Visit(E->getArg(0));
11692
11693 case Builtin::BI__builtin_ffs:
11694 case Builtin::BI__builtin_ffsl:
11695 case Builtin::BI__builtin_ffsll: {
11696 APSInt Val;
11697 if (!EvaluateInteger(E->getArg(0), Val, Info))
11698 return false;
11699
11700 unsigned N = Val.countTrailingZeros();
11701 return Success(N == Val.getBitWidth() ? 0 : N + 1, E);
11702 }
11703
11704 case Builtin::BI__builtin_fpclassify: {
11705 APFloat Val(0.0);
11706 if (!EvaluateFloat(E->getArg(5), Val, Info))
11707 return false;
11708 unsigned Arg;
11709 switch (Val.getCategory()) {
11710 case APFloat::fcNaN: Arg = 0; break;
11711 case APFloat::fcInfinity: Arg = 1; break;
11712 case APFloat::fcNormal: Arg = Val.isDenormal() ? 3 : 2; break;
11713 case APFloat::fcZero: Arg = 4; break;
11714 }
11715 return Visit(E->getArg(Arg));
11716 }
11717
11718 case Builtin::BI__builtin_isinf_sign: {
11719 APFloat Val(0.0);
11720 return EvaluateFloat(E->getArg(0), Val, Info) &&
11721 Success(Val.isInfinity() ? (Val.isNegative() ? -1 : 1) : 0, E);
11722 }
11723
11724 case Builtin::BI__builtin_isinf: {
11725 APFloat Val(0.0);
11726 return EvaluateFloat(E->getArg(0), Val, Info) &&
11727 Success(Val.isInfinity() ? 1 : 0, E);
11728 }
11729
11730 case Builtin::BI__builtin_isfinite: {
11731 APFloat Val(0.0);
11732 return EvaluateFloat(E->getArg(0), Val, Info) &&
11733 Success(Val.isFinite() ? 1 : 0, E);
11734 }
11735
11736 case Builtin::BI__builtin_isnan: {
11737 APFloat Val(0.0);
11738 return EvaluateFloat(E->getArg(0), Val, Info) &&
11739 Success(Val.isNaN() ? 1 : 0, E);
11740 }
11741
11742 case Builtin::BI__builtin_isnormal: {
11743 APFloat Val(0.0);
11744 return EvaluateFloat(E->getArg(0), Val, Info) &&
11745 Success(Val.isNormal() ? 1 : 0, E);
11746 }
11747
11748 case Builtin::BI__builtin_parity:
11749 case Builtin::BI__builtin_parityl:
11750 case Builtin::BI__builtin_parityll: {
11751 APSInt Val;
11752 if (!EvaluateInteger(E->getArg(0), Val, Info))
11753 return false;
11754
11755 return Success(Val.countPopulation() % 2, E);
11756 }
11757
11758 case Builtin::BI__builtin_popcount:
11759 case Builtin::BI__builtin_popcountl:
11760 case Builtin::BI__builtin_popcountll: {
11761 APSInt Val;
11762 if (!EvaluateInteger(E->getArg(0), Val, Info))
11763 return false;
11764
11765 return Success(Val.countPopulation(), E);
11766 }
11767
11768 case Builtin::BI__builtin_rotateleft8:
11769 case Builtin::BI__builtin_rotateleft16:
11770 case Builtin::BI__builtin_rotateleft32:
11771 case Builtin::BI__builtin_rotateleft64:
11772 case Builtin::BI_rotl8: // Microsoft variants of rotate right
11773 case Builtin::BI_rotl16:
11774 case Builtin::BI_rotl:
11775 case Builtin::BI_lrotl:
11776 case Builtin::BI_rotl64: {
11777 APSInt Val, Amt;
11778 if (!EvaluateInteger(E->getArg(0), Val, Info) ||
11779 !EvaluateInteger(E->getArg(1), Amt, Info))
11780 return false;
11781
11782 return Success(Val.rotl(Amt.urem(Val.getBitWidth())), E);
11783 }
11784
11785 case Builtin::BI__builtin_rotateright8:
11786 case Builtin::BI__builtin_rotateright16:
11787 case Builtin::BI__builtin_rotateright32:
11788 case Builtin::BI__builtin_rotateright64:
11789 case Builtin::BI_rotr8: // Microsoft variants of rotate right
11790 case Builtin::BI_rotr16:
11791 case Builtin::BI_rotr:
11792 case Builtin::BI_lrotr:
11793 case Builtin::BI_rotr64: {
11794 APSInt Val, Amt;
11795 if (!EvaluateInteger(E->getArg(0), Val, Info) ||
11796 !EvaluateInteger(E->getArg(1), Amt, Info))
11797 return false;
11798
11799 return Success(Val.rotr(Amt.urem(Val.getBitWidth())), E);
11800 }
11801
11802 case Builtin::BIstrlen:
11803 case Builtin::BIwcslen:
11804 // A call to strlen is not a constant expression.
11805 if (Info.getLangOpts().CPlusPlus11)
11806 Info.CCEDiag(E, diag::note_constexpr_invalid_function)
11807 << /*isConstexpr*/0 << /*isConstructor*/0
11808 << (std::string("'") + Info.Ctx.BuiltinInfo.getName(BuiltinOp) + "'");
11809 else
11810 Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr);
11811 LLVM_FALLTHROUGH;
11812 case Builtin::BI__builtin_strlen:
11813 case Builtin::BI__builtin_wcslen: {
11814 // As an extension, we support __builtin_strlen() as a constant expression,
11815 // and support folding strlen() to a constant.
11816 LValue String;
11817 if (!EvaluatePointer(E->getArg(0), String, Info))
11818 return false;
11819
11820 QualType CharTy = E->getArg(0)->getType()->getPointeeType();
11821
11822 // Fast path: if it's a string literal, search the string value.
11823 if (const StringLiteral *S = dyn_cast_or_null<StringLiteral>(
11824 String.getLValueBase().dyn_cast<const Expr *>())) {
11825 // The string literal may have embedded null characters. Find the first
11826 // one and truncate there.
11827 StringRef Str = S->getBytes();
11828 int64_t Off = String.Offset.getQuantity();
11829 if (Off >= 0 && (uint64_t)Off <= (uint64_t)Str.size() &&
11830 S->getCharByteWidth() == 1 &&
11831 // FIXME: Add fast-path for wchar_t too.
11832 Info.Ctx.hasSameUnqualifiedType(CharTy, Info.Ctx.CharTy)) {
11833 Str = Str.substr(Off);
11834
11835 StringRef::size_type Pos = Str.find(0);
11836 if (Pos != StringRef::npos)
11837 Str = Str.substr(0, Pos);
11838
11839 return Success(Str.size(), E);
11840 }
11841
11842 // Fall through to slow path to issue appropriate diagnostic.
11843 }
11844
11845 // Slow path: scan the bytes of the string looking for the terminating 0.
11846 for (uint64_t Strlen = 0; /**/; ++Strlen) {
11847 APValue Char;
11848 if (!handleLValueToRValueConversion(Info, E, CharTy, String, Char) ||
11849 !Char.isInt())
11850 return false;
11851 if (!Char.getInt())
11852 return Success(Strlen, E);
11853 if (!HandleLValueArrayAdjustment(Info, E, String, CharTy, 1))
11854 return false;
11855 }
11856 }
11857
11858 case Builtin::BIstrcmp:
11859 case Builtin::BIwcscmp:
11860 case Builtin::BIstrncmp:
11861 case Builtin::BIwcsncmp:
11862 case Builtin::BImemcmp:
11863 case Builtin::BIbcmp:
11864 case Builtin::BIwmemcmp:
11865 // A call to strlen is not a constant expression.
11866 if (Info.getLangOpts().CPlusPlus11)
11867 Info.CCEDiag(E, diag::note_constexpr_invalid_function)
11868 << /*isConstexpr*/0 << /*isConstructor*/0
11869 << (std::string("'") + Info.Ctx.BuiltinInfo.getName(BuiltinOp) + "'");
11870 else
11871 Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr);
11872 LLVM_FALLTHROUGH;
11873 case Builtin::BI__builtin_strcmp:
11874 case Builtin::BI__builtin_wcscmp:
11875 case Builtin::BI__builtin_strncmp:
11876 case Builtin::BI__builtin_wcsncmp:
11877 case Builtin::BI__builtin_memcmp:
11878 case Builtin::BI__builtin_bcmp:
11879 case Builtin::BI__builtin_wmemcmp: {
11880 LValue String1, String2;
11881 if (!EvaluatePointer(E->getArg(0), String1, Info) ||
11882 !EvaluatePointer(E->getArg(1), String2, Info))
11883 return false;
11884
11885 uint64_t MaxLength = uint64_t(-1);
11886 if (BuiltinOp != Builtin::BIstrcmp &&
11887 BuiltinOp != Builtin::BIwcscmp &&
11888 BuiltinOp != Builtin::BI__builtin_strcmp &&
11889 BuiltinOp != Builtin::BI__builtin_wcscmp) {
11890 APSInt N;
11891 if (!EvaluateInteger(E->getArg(2), N, Info))
11892 return false;
11893 MaxLength = N.getExtValue();
11894 }
11895
11896 // Empty substrings compare equal by definition.
11897 if (MaxLength == 0u)
11898 return Success(0, E);
11899
11900 if (!String1.checkNullPointerForFoldAccess(Info, E, AK_Read) ||
11901 !String2.checkNullPointerForFoldAccess(Info, E, AK_Read) ||
11902 String1.Designator.Invalid || String2.Designator.Invalid)
11903 return false;
11904
11905 QualType CharTy1 = String1.Designator.getType(Info.Ctx);
11906 QualType CharTy2 = String2.Designator.getType(Info.Ctx);
11907
11908 bool IsRawByte = BuiltinOp == Builtin::BImemcmp ||
11909 BuiltinOp == Builtin::BIbcmp ||
11910 BuiltinOp == Builtin::BI__builtin_memcmp ||
11911 BuiltinOp == Builtin::BI__builtin_bcmp;
11912
11913 assert(IsRawByte ||
11914 (Info.Ctx.hasSameUnqualifiedType(
11915 CharTy1, E->getArg(0)->getType()->getPointeeType()) &&
11916 Info.Ctx.hasSameUnqualifiedType(CharTy1, CharTy2)));
11917
11918 // For memcmp, allow comparing any arrays of '[[un]signed] char' or
11919 // 'char8_t', but no other types.
11920 if (IsRawByte &&
11921 !(isOneByteCharacterType(CharTy1) && isOneByteCharacterType(CharTy2))) {
11922 // FIXME: Consider using our bit_cast implementation to support this.
11923 Info.FFDiag(E, diag::note_constexpr_memcmp_unsupported)
11924 << (std::string("'") + Info.Ctx.BuiltinInfo.getName(BuiltinOp) + "'")
11925 << CharTy1 << CharTy2;
11926 return false;
11927 }
11928
11929 const auto &ReadCurElems = [&](APValue &Char1, APValue &Char2) {
11930 return handleLValueToRValueConversion(Info, E, CharTy1, String1, Char1) &&
11931 handleLValueToRValueConversion(Info, E, CharTy2, String2, Char2) &&
11932 Char1.isInt() && Char2.isInt();
11933 };
11934 const auto &AdvanceElems = [&] {
11935 return HandleLValueArrayAdjustment(Info, E, String1, CharTy1, 1) &&
11936 HandleLValueArrayAdjustment(Info, E, String2, CharTy2, 1);
11937 };
11938
11939 bool StopAtNull =
11940 (BuiltinOp != Builtin::BImemcmp && BuiltinOp != Builtin::BIbcmp &&
11941 BuiltinOp != Builtin::BIwmemcmp &&
11942 BuiltinOp != Builtin::BI__builtin_memcmp &&
11943 BuiltinOp != Builtin::BI__builtin_bcmp &&
11944 BuiltinOp != Builtin::BI__builtin_wmemcmp);
11945 bool IsWide = BuiltinOp == Builtin::BIwcscmp ||
11946 BuiltinOp == Builtin::BIwcsncmp ||
11947 BuiltinOp == Builtin::BIwmemcmp ||
11948 BuiltinOp == Builtin::BI__builtin_wcscmp ||
11949 BuiltinOp == Builtin::BI__builtin_wcsncmp ||
11950 BuiltinOp == Builtin::BI__builtin_wmemcmp;
11951
11952 for (; MaxLength; --MaxLength) {
11953 APValue Char1, Char2;
11954 if (!ReadCurElems(Char1, Char2))
11955 return false;
11956 if (Char1.getInt().ne(Char2.getInt())) {
11957 if (IsWide) // wmemcmp compares with wchar_t signedness.
11958 return Success(Char1.getInt() < Char2.getInt() ? -1 : 1, E);
11959 // memcmp always compares unsigned chars.
11960 return Success(Char1.getInt().ult(Char2.getInt()) ? -1 : 1, E);
11961 }
11962 if (StopAtNull && !Char1.getInt())
11963 return Success(0, E);
11964 assert(!(StopAtNull && !Char2.getInt()));
11965 if (!AdvanceElems())
11966 return false;
11967 }
11968 // We hit the strncmp / memcmp limit.
11969 return Success(0, E);
11970 }
11971
11972 case Builtin::BI__atomic_always_lock_free:
11973 case Builtin::BI__atomic_is_lock_free:
11974 case Builtin::BI__c11_atomic_is_lock_free: {
11975 APSInt SizeVal;
11976 if (!EvaluateInteger(E->getArg(0), SizeVal, Info))
11977 return false;
11978
11979 // For __atomic_is_lock_free(sizeof(_Atomic(T))), if the size is a power
11980 // of two less than or equal to the maximum inline atomic width, we know it
11981 // is lock-free. If the size isn't a power of two, or greater than the
11982 // maximum alignment where we promote atomics, we know it is not lock-free
11983 // (at least not in the sense of atomic_is_lock_free). Otherwise,
11984 // the answer can only be determined at runtime; for example, 16-byte
11985 // atomics have lock-free implementations on some, but not all,
11986 // x86-64 processors.
11987
11988 // Check power-of-two.
11989 CharUnits Size = CharUnits::fromQuantity(SizeVal.getZExtValue());
11990 if (Size.isPowerOfTwo()) {
11991 // Check against inlining width.
11992 unsigned InlineWidthBits =
11993 Info.Ctx.getTargetInfo().getMaxAtomicInlineWidth();
11994 if (Size <= Info.Ctx.toCharUnitsFromBits(InlineWidthBits)) {
11995 if (BuiltinOp == Builtin::BI__c11_atomic_is_lock_free ||
11996 Size == CharUnits::One() ||
11997 E->getArg(1)->isNullPointerConstant(Info.Ctx,
11998 Expr::NPC_NeverValueDependent))
11999 // OK, we will inline appropriately-aligned operations of this size,
12000 // and _Atomic(T) is appropriately-aligned.
12001 return Success(1, E);
12002
12003 QualType PointeeType = E->getArg(1)->IgnoreImpCasts()->getType()->
12004 castAs<PointerType>()->getPointeeType();
12005 if (!PointeeType->isIncompleteType() &&
12006 Info.Ctx.getTypeAlignInChars(PointeeType) >= Size) {
12007 // OK, we will inline operations on this object.
12008 return Success(1, E);
12009 }
12010 }
12011 }
12012
12013 return BuiltinOp == Builtin::BI__atomic_always_lock_free ?
12014 Success(0, E) : Error(E);
12015 }
12016 case Builtin::BI__builtin_add_overflow:
12017 case Builtin::BI__builtin_sub_overflow:
12018 case Builtin::BI__builtin_mul_overflow:
12019 case Builtin::BI__builtin_sadd_overflow:
12020 case Builtin::BI__builtin_uadd_overflow:
12021 case Builtin::BI__builtin_uaddl_overflow:
12022 case Builtin::BI__builtin_uaddll_overflow:
12023 case Builtin::BI__builtin_usub_overflow:
12024 case Builtin::BI__builtin_usubl_overflow:
12025 case Builtin::BI__builtin_usubll_overflow:
12026 case Builtin::BI__builtin_umul_overflow:
12027 case Builtin::BI__builtin_umull_overflow:
12028 case Builtin::BI__builtin_umulll_overflow:
12029 case Builtin::BI__builtin_saddl_overflow:
12030 case Builtin::BI__builtin_saddll_overflow:
12031 case Builtin::BI__builtin_ssub_overflow:
12032 case Builtin::BI__builtin_ssubl_overflow:
12033 case Builtin::BI__builtin_ssubll_overflow:
12034 case Builtin::BI__builtin_smul_overflow:
12035 case Builtin::BI__builtin_smull_overflow:
12036 case Builtin::BI__builtin_smulll_overflow: {
12037 LValue ResultLValue;
12038 APSInt LHS, RHS;
12039
12040 QualType ResultType = E->getArg(2)->getType()->getPointeeType();
12041 if (!EvaluateInteger(E->getArg(0), LHS, Info) ||
12042 !EvaluateInteger(E->getArg(1), RHS, Info) ||
12043 !EvaluatePointer(E->getArg(2), ResultLValue, Info))
12044 return false;
12045
12046 APSInt Result;
12047 bool DidOverflow = false;
12048
12049 // If the types don't have to match, enlarge all 3 to the largest of them.
12050 if (BuiltinOp == Builtin::BI__builtin_add_overflow ||
12051 BuiltinOp == Builtin::BI__builtin_sub_overflow ||
12052 BuiltinOp == Builtin::BI__builtin_mul_overflow) {
12053 bool IsSigned = LHS.isSigned() || RHS.isSigned() ||
12054 ResultType->isSignedIntegerOrEnumerationType();
12055 bool AllSigned = LHS.isSigned() && RHS.isSigned() &&
12056 ResultType->isSignedIntegerOrEnumerationType();
12057 uint64_t LHSSize = LHS.getBitWidth();
12058 uint64_t RHSSize = RHS.getBitWidth();
12059 uint64_t ResultSize = Info.Ctx.getTypeSize(ResultType);
12060 uint64_t MaxBits = std::max(std::max(LHSSize, RHSSize), ResultSize);
12061
12062 // Add an additional bit if the signedness isn't uniformly agreed to. We
12063 // could do this ONLY if there is a signed and an unsigned that both have
12064 // MaxBits, but the code to check that is pretty nasty. The issue will be
12065 // caught in the shrink-to-result later anyway.
12066 if (IsSigned && !AllSigned)
12067 ++MaxBits;
12068
12069 LHS = APSInt(LHS.extOrTrunc(MaxBits), !IsSigned);
12070 RHS = APSInt(RHS.extOrTrunc(MaxBits), !IsSigned);
12071 Result = APSInt(MaxBits, !IsSigned);
12072 }
12073
12074 // Find largest int.
12075 switch (BuiltinOp) {
12076 default:
12077 llvm_unreachable("Invalid value for BuiltinOp");
12078 case Builtin::BI__builtin_add_overflow:
12079 case Builtin::BI__builtin_sadd_overflow:
12080 case Builtin::BI__builtin_saddl_overflow:
12081 case Builtin::BI__builtin_saddll_overflow:
12082 case Builtin::BI__builtin_uadd_overflow:
12083 case Builtin::BI__builtin_uaddl_overflow:
12084 case Builtin::BI__builtin_uaddll_overflow:
12085 Result = LHS.isSigned() ? LHS.sadd_ov(RHS, DidOverflow)
12086 : LHS.uadd_ov(RHS, DidOverflow);
12087 break;
12088 case Builtin::BI__builtin_sub_overflow:
12089 case Builtin::BI__builtin_ssub_overflow:
12090 case Builtin::BI__builtin_ssubl_overflow:
12091 case Builtin::BI__builtin_ssubll_overflow:
12092 case Builtin::BI__builtin_usub_overflow:
12093 case Builtin::BI__builtin_usubl_overflow:
12094 case Builtin::BI__builtin_usubll_overflow:
12095 Result = LHS.isSigned() ? LHS.ssub_ov(RHS, DidOverflow)
12096 : LHS.usub_ov(RHS, DidOverflow);
12097 break;
12098 case Builtin::BI__builtin_mul_overflow:
12099 case Builtin::BI__builtin_smul_overflow:
12100 case Builtin::BI__builtin_smull_overflow:
12101 case Builtin::BI__builtin_smulll_overflow:
12102 case Builtin::BI__builtin_umul_overflow:
12103 case Builtin::BI__builtin_umull_overflow:
12104 case Builtin::BI__builtin_umulll_overflow:
12105 Result = LHS.isSigned() ? LHS.smul_ov(RHS, DidOverflow)
12106 : LHS.umul_ov(RHS, DidOverflow);
12107 break;
12108 }
12109
12110 // In the case where multiple sizes are allowed, truncate and see if
12111 // the values are the same.
12112 if (BuiltinOp == Builtin::BI__builtin_add_overflow ||
12113 BuiltinOp == Builtin::BI__builtin_sub_overflow ||
12114 BuiltinOp == Builtin::BI__builtin_mul_overflow) {
12115 // APSInt doesn't have a TruncOrSelf, so we use extOrTrunc instead,
12116 // since it will give us the behavior of a TruncOrSelf in the case where
12117 // its parameter <= its size. We previously set Result to be at least the
12118 // type-size of the result, so getTypeSize(ResultType) <= Result.BitWidth
12119 // will work exactly like TruncOrSelf.
12120 APSInt Temp = Result.extOrTrunc(Info.Ctx.getTypeSize(ResultType));
12121 Temp.setIsSigned(ResultType->isSignedIntegerOrEnumerationType());
12122
12123 if (!APSInt::isSameValue(Temp, Result))
12124 DidOverflow = true;
12125 Result = Temp;
12126 }
12127
12128 APValue APV{Result};
12129 if (!handleAssignment(Info, E, ResultLValue, ResultType, APV))
12130 return false;
12131 return Success(DidOverflow, E);
12132 }
12133 }
12134 }
12135
12136 /// Determine whether this is a pointer past the end of the complete
12137 /// object referred to by the lvalue.
isOnePastTheEndOfCompleteObject(const ASTContext & Ctx,const LValue & LV)12138 static bool isOnePastTheEndOfCompleteObject(const ASTContext &Ctx,
12139 const LValue &LV) {
12140 // A null pointer can be viewed as being "past the end" but we don't
12141 // choose to look at it that way here.
12142 if (!LV.getLValueBase())
12143 return false;
12144
12145 // If the designator is valid and refers to a subobject, we're not pointing
12146 // past the end.
12147 if (!LV.getLValueDesignator().Invalid &&
12148 !LV.getLValueDesignator().isOnePastTheEnd())
12149 return false;
12150
12151 // A pointer to an incomplete type might be past-the-end if the type's size is
12152 // zero. We cannot tell because the type is incomplete.
12153 QualType Ty = getType(LV.getLValueBase());
12154 if (Ty->isIncompleteType())
12155 return true;
12156
12157 // We're a past-the-end pointer if we point to the byte after the object,
12158 // no matter what our type or path is.
12159 auto Size = Ctx.getTypeSizeInChars(Ty);
12160 return LV.getLValueOffset() == Size;
12161 }
12162
12163 namespace {
12164
12165 /// Data recursive integer evaluator of certain binary operators.
12166 ///
12167 /// We use a data recursive algorithm for binary operators so that we are able
12168 /// to handle extreme cases of chained binary operators without causing stack
12169 /// overflow.
12170 class DataRecursiveIntBinOpEvaluator {
12171 struct EvalResult {
12172 APValue Val;
12173 bool Failed;
12174
EvalResult__anon6b379bbb2811::DataRecursiveIntBinOpEvaluator::EvalResult12175 EvalResult() : Failed(false) { }
12176
swap__anon6b379bbb2811::DataRecursiveIntBinOpEvaluator::EvalResult12177 void swap(EvalResult &RHS) {
12178 Val.swap(RHS.Val);
12179 Failed = RHS.Failed;
12180 RHS.Failed = false;
12181 }
12182 };
12183
12184 struct Job {
12185 const Expr *E;
12186 EvalResult LHSResult; // meaningful only for binary operator expression.
12187 enum { AnyExprKind, BinOpKind, BinOpVisitedLHSKind } Kind;
12188
12189 Job() = default;
12190 Job(Job &&) = default;
12191
startSpeculativeEval__anon6b379bbb2811::DataRecursiveIntBinOpEvaluator::Job12192 void startSpeculativeEval(EvalInfo &Info) {
12193 SpecEvalRAII = SpeculativeEvaluationRAII(Info);
12194 }
12195
12196 private:
12197 SpeculativeEvaluationRAII SpecEvalRAII;
12198 };
12199
12200 SmallVector<Job, 16> Queue;
12201
12202 IntExprEvaluator &IntEval;
12203 EvalInfo &Info;
12204 APValue &FinalResult;
12205
12206 public:
DataRecursiveIntBinOpEvaluator(IntExprEvaluator & IntEval,APValue & Result)12207 DataRecursiveIntBinOpEvaluator(IntExprEvaluator &IntEval, APValue &Result)
12208 : IntEval(IntEval), Info(IntEval.getEvalInfo()), FinalResult(Result) { }
12209
12210 /// True if \param E is a binary operator that we are going to handle
12211 /// data recursively.
12212 /// We handle binary operators that are comma, logical, or that have operands
12213 /// with integral or enumeration type.
shouldEnqueue(const BinaryOperator * E)12214 static bool shouldEnqueue(const BinaryOperator *E) {
12215 return E->getOpcode() == BO_Comma || E->isLogicalOp() ||
12216 (E->isRValue() && E->getType()->isIntegralOrEnumerationType() &&
12217 E->getLHS()->getType()->isIntegralOrEnumerationType() &&
12218 E->getRHS()->getType()->isIntegralOrEnumerationType());
12219 }
12220
Traverse(const BinaryOperator * E)12221 bool Traverse(const BinaryOperator *E) {
12222 enqueue(E);
12223 EvalResult PrevResult;
12224 while (!Queue.empty())
12225 process(PrevResult);
12226
12227 if (PrevResult.Failed) return false;
12228
12229 FinalResult.swap(PrevResult.Val);
12230 return true;
12231 }
12232
12233 private:
Success(uint64_t Value,const Expr * E,APValue & Result)12234 bool Success(uint64_t Value, const Expr *E, APValue &Result) {
12235 return IntEval.Success(Value, E, Result);
12236 }
Success(const APSInt & Value,const Expr * E,APValue & Result)12237 bool Success(const APSInt &Value, const Expr *E, APValue &Result) {
12238 return IntEval.Success(Value, E, Result);
12239 }
Error(const Expr * E)12240 bool Error(const Expr *E) {
12241 return IntEval.Error(E);
12242 }
Error(const Expr * E,diag::kind D)12243 bool Error(const Expr *E, diag::kind D) {
12244 return IntEval.Error(E, D);
12245 }
12246
CCEDiag(const Expr * E,diag::kind D)12247 OptionalDiagnostic CCEDiag(const Expr *E, diag::kind D) {
12248 return Info.CCEDiag(E, D);
12249 }
12250
12251 // Returns true if visiting the RHS is necessary, false otherwise.
12252 bool VisitBinOpLHSOnly(EvalResult &LHSResult, const BinaryOperator *E,
12253 bool &SuppressRHSDiags);
12254
12255 bool VisitBinOp(const EvalResult &LHSResult, const EvalResult &RHSResult,
12256 const BinaryOperator *E, APValue &Result);
12257
EvaluateExpr(const Expr * E,EvalResult & Result)12258 void EvaluateExpr(const Expr *E, EvalResult &Result) {
12259 Result.Failed = !Evaluate(Result.Val, Info, E);
12260 if (Result.Failed)
12261 Result.Val = APValue();
12262 }
12263
12264 void process(EvalResult &Result);
12265
enqueue(const Expr * E)12266 void enqueue(const Expr *E) {
12267 E = E->IgnoreParens();
12268 Queue.resize(Queue.size()+1);
12269 Queue.back().E = E;
12270 Queue.back().Kind = Job::AnyExprKind;
12271 }
12272 };
12273
12274 }
12275
12276 bool DataRecursiveIntBinOpEvaluator::
VisitBinOpLHSOnly(EvalResult & LHSResult,const BinaryOperator * E,bool & SuppressRHSDiags)12277 VisitBinOpLHSOnly(EvalResult &LHSResult, const BinaryOperator *E,
12278 bool &SuppressRHSDiags) {
12279 if (E->getOpcode() == BO_Comma) {
12280 // Ignore LHS but note if we could not evaluate it.
12281 if (LHSResult.Failed)
12282 return Info.noteSideEffect();
12283 return true;
12284 }
12285
12286 if (E->isLogicalOp()) {
12287 bool LHSAsBool;
12288 if (!LHSResult.Failed && HandleConversionToBool(LHSResult.Val, LHSAsBool)) {
12289 // We were able to evaluate the LHS, see if we can get away with not
12290 // evaluating the RHS: 0 && X -> 0, 1 || X -> 1
12291 if (LHSAsBool == (E->getOpcode() == BO_LOr)) {
12292 Success(LHSAsBool, E, LHSResult.Val);
12293 return false; // Ignore RHS
12294 }
12295 } else {
12296 LHSResult.Failed = true;
12297
12298 // Since we weren't able to evaluate the left hand side, it
12299 // might have had side effects.
12300 if (!Info.noteSideEffect())
12301 return false;
12302
12303 // We can't evaluate the LHS; however, sometimes the result
12304 // is determined by the RHS: X && 0 -> 0, X || 1 -> 1.
12305 // Don't ignore RHS and suppress diagnostics from this arm.
12306 SuppressRHSDiags = true;
12307 }
12308
12309 return true;
12310 }
12311
12312 assert(E->getLHS()->getType()->isIntegralOrEnumerationType() &&
12313 E->getRHS()->getType()->isIntegralOrEnumerationType());
12314
12315 if (LHSResult.Failed && !Info.noteFailure())
12316 return false; // Ignore RHS;
12317
12318 return true;
12319 }
12320
addOrSubLValueAsInteger(APValue & LVal,const APSInt & Index,bool IsSub)12321 static void addOrSubLValueAsInteger(APValue &LVal, const APSInt &Index,
12322 bool IsSub) {
12323 // Compute the new offset in the appropriate width, wrapping at 64 bits.
12324 // FIXME: When compiling for a 32-bit target, we should use 32-bit
12325 // offsets.
12326 assert(!LVal.hasLValuePath() && "have designator for integer lvalue");
12327 CharUnits &Offset = LVal.getLValueOffset();
12328 uint64_t Offset64 = Offset.getQuantity();
12329 uint64_t Index64 = Index.extOrTrunc(64).getZExtValue();
12330 Offset = CharUnits::fromQuantity(IsSub ? Offset64 - Index64
12331 : Offset64 + Index64);
12332 }
12333
12334 bool DataRecursiveIntBinOpEvaluator::
VisitBinOp(const EvalResult & LHSResult,const EvalResult & RHSResult,const BinaryOperator * E,APValue & Result)12335 VisitBinOp(const EvalResult &LHSResult, const EvalResult &RHSResult,
12336 const BinaryOperator *E, APValue &Result) {
12337 if (E->getOpcode() == BO_Comma) {
12338 if (RHSResult.Failed)
12339 return false;
12340 Result = RHSResult.Val;
12341 return true;
12342 }
12343
12344 if (E->isLogicalOp()) {
12345 bool lhsResult, rhsResult;
12346 bool LHSIsOK = HandleConversionToBool(LHSResult.Val, lhsResult);
12347 bool RHSIsOK = HandleConversionToBool(RHSResult.Val, rhsResult);
12348
12349 if (LHSIsOK) {
12350 if (RHSIsOK) {
12351 if (E->getOpcode() == BO_LOr)
12352 return Success(lhsResult || rhsResult, E, Result);
12353 else
12354 return Success(lhsResult && rhsResult, E, Result);
12355 }
12356 } else {
12357 if (RHSIsOK) {
12358 // We can't evaluate the LHS; however, sometimes the result
12359 // is determined by the RHS: X && 0 -> 0, X || 1 -> 1.
12360 if (rhsResult == (E->getOpcode() == BO_LOr))
12361 return Success(rhsResult, E, Result);
12362 }
12363 }
12364
12365 return false;
12366 }
12367
12368 assert(E->getLHS()->getType()->isIntegralOrEnumerationType() &&
12369 E->getRHS()->getType()->isIntegralOrEnumerationType());
12370
12371 if (LHSResult.Failed || RHSResult.Failed)
12372 return false;
12373
12374 const APValue &LHSVal = LHSResult.Val;
12375 const APValue &RHSVal = RHSResult.Val;
12376
12377 // Handle cases like (unsigned long)&a + 4.
12378 if (E->isAdditiveOp() && LHSVal.isLValue() && RHSVal.isInt()) {
12379 Result = LHSVal;
12380 addOrSubLValueAsInteger(Result, RHSVal.getInt(), E->getOpcode() == BO_Sub);
12381 return true;
12382 }
12383
12384 // Handle cases like 4 + (unsigned long)&a
12385 if (E->getOpcode() == BO_Add &&
12386 RHSVal.isLValue() && LHSVal.isInt()) {
12387 Result = RHSVal;
12388 addOrSubLValueAsInteger(Result, LHSVal.getInt(), /*IsSub*/false);
12389 return true;
12390 }
12391
12392 if (E->getOpcode() == BO_Sub && LHSVal.isLValue() && RHSVal.isLValue()) {
12393 // Handle (intptr_t)&&A - (intptr_t)&&B.
12394 if (!LHSVal.getLValueOffset().isZero() ||
12395 !RHSVal.getLValueOffset().isZero())
12396 return false;
12397 const Expr *LHSExpr = LHSVal.getLValueBase().dyn_cast<const Expr*>();
12398 const Expr *RHSExpr = RHSVal.getLValueBase().dyn_cast<const Expr*>();
12399 if (!LHSExpr || !RHSExpr)
12400 return false;
12401 const AddrLabelExpr *LHSAddrExpr = dyn_cast<AddrLabelExpr>(LHSExpr);
12402 const AddrLabelExpr *RHSAddrExpr = dyn_cast<AddrLabelExpr>(RHSExpr);
12403 if (!LHSAddrExpr || !RHSAddrExpr)
12404 return false;
12405 // Make sure both labels come from the same function.
12406 if (LHSAddrExpr->getLabel()->getDeclContext() !=
12407 RHSAddrExpr->getLabel()->getDeclContext())
12408 return false;
12409 Result = APValue(LHSAddrExpr, RHSAddrExpr);
12410 return true;
12411 }
12412
12413 // All the remaining cases expect both operands to be an integer
12414 if (!LHSVal.isInt() || !RHSVal.isInt())
12415 return Error(E);
12416
12417 // Set up the width and signedness manually, in case it can't be deduced
12418 // from the operation we're performing.
12419 // FIXME: Don't do this in the cases where we can deduce it.
12420 APSInt Value(Info.Ctx.getIntWidth(E->getType()),
12421 E->getType()->isUnsignedIntegerOrEnumerationType());
12422 if (!handleIntIntBinOp(Info, E, LHSVal.getInt(), E->getOpcode(),
12423 RHSVal.getInt(), Value))
12424 return false;
12425 return Success(Value, E, Result);
12426 }
12427
process(EvalResult & Result)12428 void DataRecursiveIntBinOpEvaluator::process(EvalResult &Result) {
12429 Job &job = Queue.back();
12430
12431 switch (job.Kind) {
12432 case Job::AnyExprKind: {
12433 if (const BinaryOperator *Bop = dyn_cast<BinaryOperator>(job.E)) {
12434 if (shouldEnqueue(Bop)) {
12435 job.Kind = Job::BinOpKind;
12436 enqueue(Bop->getLHS());
12437 return;
12438 }
12439 }
12440
12441 EvaluateExpr(job.E, Result);
12442 Queue.pop_back();
12443 return;
12444 }
12445
12446 case Job::BinOpKind: {
12447 const BinaryOperator *Bop = cast<BinaryOperator>(job.E);
12448 bool SuppressRHSDiags = false;
12449 if (!VisitBinOpLHSOnly(Result, Bop, SuppressRHSDiags)) {
12450 Queue.pop_back();
12451 return;
12452 }
12453 if (SuppressRHSDiags)
12454 job.startSpeculativeEval(Info);
12455 job.LHSResult.swap(Result);
12456 job.Kind = Job::BinOpVisitedLHSKind;
12457 enqueue(Bop->getRHS());
12458 return;
12459 }
12460
12461 case Job::BinOpVisitedLHSKind: {
12462 const BinaryOperator *Bop = cast<BinaryOperator>(job.E);
12463 EvalResult RHS;
12464 RHS.swap(Result);
12465 Result.Failed = !VisitBinOp(job.LHSResult, RHS, Bop, Result.Val);
12466 Queue.pop_back();
12467 return;
12468 }
12469 }
12470
12471 llvm_unreachable("Invalid Job::Kind!");
12472 }
12473
12474 namespace {
12475 enum class CmpResult {
12476 Unequal,
12477 Less,
12478 Equal,
12479 Greater,
12480 Unordered,
12481 };
12482 }
12483
12484 template <class SuccessCB, class AfterCB>
12485 static bool
EvaluateComparisonBinaryOperator(EvalInfo & Info,const BinaryOperator * E,SuccessCB && Success,AfterCB && DoAfter)12486 EvaluateComparisonBinaryOperator(EvalInfo &Info, const BinaryOperator *E,
12487 SuccessCB &&Success, AfterCB &&DoAfter) {
12488 assert(!E->isValueDependent());
12489 assert(E->isComparisonOp() && "expected comparison operator");
12490 assert((E->getOpcode() == BO_Cmp ||
12491 E->getType()->isIntegralOrEnumerationType()) &&
12492 "unsupported binary expression evaluation");
12493 auto Error = [&](const Expr *E) {
12494 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
12495 return false;
12496 };
12497
12498 bool IsRelational = E->isRelationalOp() || E->getOpcode() == BO_Cmp;
12499 bool IsEquality = E->isEqualityOp();
12500
12501 QualType LHSTy = E->getLHS()->getType();
12502 QualType RHSTy = E->getRHS()->getType();
12503
12504 if (LHSTy->isIntegralOrEnumerationType() &&
12505 RHSTy->isIntegralOrEnumerationType()) {
12506 APSInt LHS, RHS;
12507 bool LHSOK = EvaluateInteger(E->getLHS(), LHS, Info);
12508 if (!LHSOK && !Info.noteFailure())
12509 return false;
12510 if (!EvaluateInteger(E->getRHS(), RHS, Info) || !LHSOK)
12511 return false;
12512 if (LHS < RHS)
12513 return Success(CmpResult::Less, E);
12514 if (LHS > RHS)
12515 return Success(CmpResult::Greater, E);
12516 return Success(CmpResult::Equal, E);
12517 }
12518
12519 if (LHSTy->isFixedPointType() || RHSTy->isFixedPointType()) {
12520 APFixedPoint LHSFX(Info.Ctx.getFixedPointSemantics(LHSTy));
12521 APFixedPoint RHSFX(Info.Ctx.getFixedPointSemantics(RHSTy));
12522
12523 bool LHSOK = EvaluateFixedPointOrInteger(E->getLHS(), LHSFX, Info);
12524 if (!LHSOK && !Info.noteFailure())
12525 return false;
12526 if (!EvaluateFixedPointOrInteger(E->getRHS(), RHSFX, Info) || !LHSOK)
12527 return false;
12528 if (LHSFX < RHSFX)
12529 return Success(CmpResult::Less, E);
12530 if (LHSFX > RHSFX)
12531 return Success(CmpResult::Greater, E);
12532 return Success(CmpResult::Equal, E);
12533 }
12534
12535 if (LHSTy->isAnyComplexType() || RHSTy->isAnyComplexType()) {
12536 ComplexValue LHS, RHS;
12537 bool LHSOK;
12538 if (E->isAssignmentOp()) {
12539 LValue LV;
12540 EvaluateLValue(E->getLHS(), LV, Info);
12541 LHSOK = false;
12542 } else if (LHSTy->isRealFloatingType()) {
12543 LHSOK = EvaluateFloat(E->getLHS(), LHS.FloatReal, Info);
12544 if (LHSOK) {
12545 LHS.makeComplexFloat();
12546 LHS.FloatImag = APFloat(LHS.FloatReal.getSemantics());
12547 }
12548 } else {
12549 LHSOK = EvaluateComplex(E->getLHS(), LHS, Info);
12550 }
12551 if (!LHSOK && !Info.noteFailure())
12552 return false;
12553
12554 if (E->getRHS()->getType()->isRealFloatingType()) {
12555 if (!EvaluateFloat(E->getRHS(), RHS.FloatReal, Info) || !LHSOK)
12556 return false;
12557 RHS.makeComplexFloat();
12558 RHS.FloatImag = APFloat(RHS.FloatReal.getSemantics());
12559 } else if (!EvaluateComplex(E->getRHS(), RHS, Info) || !LHSOK)
12560 return false;
12561
12562 if (LHS.isComplexFloat()) {
12563 APFloat::cmpResult CR_r =
12564 LHS.getComplexFloatReal().compare(RHS.getComplexFloatReal());
12565 APFloat::cmpResult CR_i =
12566 LHS.getComplexFloatImag().compare(RHS.getComplexFloatImag());
12567 bool IsEqual = CR_r == APFloat::cmpEqual && CR_i == APFloat::cmpEqual;
12568 return Success(IsEqual ? CmpResult::Equal : CmpResult::Unequal, E);
12569 } else {
12570 assert(IsEquality && "invalid complex comparison");
12571 bool IsEqual = LHS.getComplexIntReal() == RHS.getComplexIntReal() &&
12572 LHS.getComplexIntImag() == RHS.getComplexIntImag();
12573 return Success(IsEqual ? CmpResult::Equal : CmpResult::Unequal, E);
12574 }
12575 }
12576
12577 if (LHSTy->isRealFloatingType() &&
12578 RHSTy->isRealFloatingType()) {
12579 APFloat RHS(0.0), LHS(0.0);
12580
12581 bool LHSOK = EvaluateFloat(E->getRHS(), RHS, Info);
12582 if (!LHSOK && !Info.noteFailure())
12583 return false;
12584
12585 if (!EvaluateFloat(E->getLHS(), LHS, Info) || !LHSOK)
12586 return false;
12587
12588 assert(E->isComparisonOp() && "Invalid binary operator!");
12589 llvm::APFloatBase::cmpResult APFloatCmpResult = LHS.compare(RHS);
12590 if (!Info.InConstantContext &&
12591 APFloatCmpResult == APFloat::cmpUnordered &&
12592 E->getFPFeaturesInEffect(Info.Ctx.getLangOpts()).isFPConstrained()) {
12593 // Note: Compares may raise invalid in some cases involving NaN or sNaN.
12594 Info.FFDiag(E, diag::note_constexpr_float_arithmetic_strict);
12595 return false;
12596 }
12597 auto GetCmpRes = [&]() {
12598 switch (APFloatCmpResult) {
12599 case APFloat::cmpEqual:
12600 return CmpResult::Equal;
12601 case APFloat::cmpLessThan:
12602 return CmpResult::Less;
12603 case APFloat::cmpGreaterThan:
12604 return CmpResult::Greater;
12605 case APFloat::cmpUnordered:
12606 return CmpResult::Unordered;
12607 }
12608 llvm_unreachable("Unrecognised APFloat::cmpResult enum");
12609 };
12610 return Success(GetCmpRes(), E);
12611 }
12612
12613 if (LHSTy->isPointerType() && RHSTy->isPointerType()) {
12614 LValue LHSValue, RHSValue;
12615
12616 bool LHSOK = EvaluatePointer(E->getLHS(), LHSValue, Info);
12617 if (!LHSOK && !Info.noteFailure())
12618 return false;
12619
12620 if (!EvaluatePointer(E->getRHS(), RHSValue, Info) || !LHSOK)
12621 return false;
12622
12623 // Reject differing bases from the normal codepath; we special-case
12624 // comparisons to null.
12625 if (!HasSameBase(LHSValue, RHSValue)) {
12626 // Inequalities and subtractions between unrelated pointers have
12627 // unspecified or undefined behavior.
12628 if (!IsEquality) {
12629 Info.FFDiag(E, diag::note_constexpr_pointer_comparison_unspecified);
12630 return false;
12631 }
12632 // A constant address may compare equal to the address of a symbol.
12633 // The one exception is that address of an object cannot compare equal
12634 // to a null pointer constant.
12635 if ((!LHSValue.Base && !LHSValue.Offset.isZero()) ||
12636 (!RHSValue.Base && !RHSValue.Offset.isZero()))
12637 return Error(E);
12638 // It's implementation-defined whether distinct literals will have
12639 // distinct addresses. In clang, the result of such a comparison is
12640 // unspecified, so it is not a constant expression. However, we do know
12641 // that the address of a literal will be non-null.
12642 if ((IsLiteralLValue(LHSValue) || IsLiteralLValue(RHSValue)) &&
12643 LHSValue.Base && RHSValue.Base)
12644 return Error(E);
12645 // We can't tell whether weak symbols will end up pointing to the same
12646 // object.
12647 if (IsWeakLValue(LHSValue) || IsWeakLValue(RHSValue))
12648 return Error(E);
12649 // We can't compare the address of the start of one object with the
12650 // past-the-end address of another object, per C++ DR1652.
12651 if ((LHSValue.Base && LHSValue.Offset.isZero() &&
12652 isOnePastTheEndOfCompleteObject(Info.Ctx, RHSValue)) ||
12653 (RHSValue.Base && RHSValue.Offset.isZero() &&
12654 isOnePastTheEndOfCompleteObject(Info.Ctx, LHSValue)))
12655 return Error(E);
12656 // We can't tell whether an object is at the same address as another
12657 // zero sized object.
12658 if ((RHSValue.Base && isZeroSized(LHSValue)) ||
12659 (LHSValue.Base && isZeroSized(RHSValue)))
12660 return Error(E);
12661 return Success(CmpResult::Unequal, E);
12662 }
12663
12664 const CharUnits &LHSOffset = LHSValue.getLValueOffset();
12665 const CharUnits &RHSOffset = RHSValue.getLValueOffset();
12666
12667 SubobjectDesignator &LHSDesignator = LHSValue.getLValueDesignator();
12668 SubobjectDesignator &RHSDesignator = RHSValue.getLValueDesignator();
12669
12670 // C++11 [expr.rel]p3:
12671 // Pointers to void (after pointer conversions) can be compared, with a
12672 // result defined as follows: If both pointers represent the same
12673 // address or are both the null pointer value, the result is true if the
12674 // operator is <= or >= and false otherwise; otherwise the result is
12675 // unspecified.
12676 // We interpret this as applying to pointers to *cv* void.
12677 if (LHSTy->isVoidPointerType() && LHSOffset != RHSOffset && IsRelational)
12678 Info.CCEDiag(E, diag::note_constexpr_void_comparison);
12679
12680 // C++11 [expr.rel]p2:
12681 // - If two pointers point to non-static data members of the same object,
12682 // or to subobjects or array elements fo such members, recursively, the
12683 // pointer to the later declared member compares greater provided the
12684 // two members have the same access control and provided their class is
12685 // not a union.
12686 // [...]
12687 // - Otherwise pointer comparisons are unspecified.
12688 if (!LHSDesignator.Invalid && !RHSDesignator.Invalid && IsRelational) {
12689 bool WasArrayIndex;
12690 unsigned Mismatch = FindDesignatorMismatch(
12691 getType(LHSValue.Base), LHSDesignator, RHSDesignator, WasArrayIndex);
12692 // At the point where the designators diverge, the comparison has a
12693 // specified value if:
12694 // - we are comparing array indices
12695 // - we are comparing fields of a union, or fields with the same access
12696 // Otherwise, the result is unspecified and thus the comparison is not a
12697 // constant expression.
12698 if (!WasArrayIndex && Mismatch < LHSDesignator.Entries.size() &&
12699 Mismatch < RHSDesignator.Entries.size()) {
12700 const FieldDecl *LF = getAsField(LHSDesignator.Entries[Mismatch]);
12701 const FieldDecl *RF = getAsField(RHSDesignator.Entries[Mismatch]);
12702 if (!LF && !RF)
12703 Info.CCEDiag(E, diag::note_constexpr_pointer_comparison_base_classes);
12704 else if (!LF)
12705 Info.CCEDiag(E, diag::note_constexpr_pointer_comparison_base_field)
12706 << getAsBaseClass(LHSDesignator.Entries[Mismatch])
12707 << RF->getParent() << RF;
12708 else if (!RF)
12709 Info.CCEDiag(E, diag::note_constexpr_pointer_comparison_base_field)
12710 << getAsBaseClass(RHSDesignator.Entries[Mismatch])
12711 << LF->getParent() << LF;
12712 else if (!LF->getParent()->isUnion() &&
12713 LF->getAccess() != RF->getAccess())
12714 Info.CCEDiag(E,
12715 diag::note_constexpr_pointer_comparison_differing_access)
12716 << LF << LF->getAccess() << RF << RF->getAccess()
12717 << LF->getParent();
12718 }
12719 }
12720
12721 // The comparison here must be unsigned, and performed with the same
12722 // width as the pointer.
12723 unsigned PtrSize = Info.Ctx.getTypeSize(LHSTy);
12724 uint64_t CompareLHS = LHSOffset.getQuantity();
12725 uint64_t CompareRHS = RHSOffset.getQuantity();
12726 assert(PtrSize <= 64 && "Unexpected pointer width");
12727 uint64_t Mask = ~0ULL >> (64 - PtrSize);
12728 CompareLHS &= Mask;
12729 CompareRHS &= Mask;
12730
12731 // If there is a base and this is a relational operator, we can only
12732 // compare pointers within the object in question; otherwise, the result
12733 // depends on where the object is located in memory.
12734 if (!LHSValue.Base.isNull() && IsRelational) {
12735 QualType BaseTy = getType(LHSValue.Base);
12736 if (BaseTy->isIncompleteType())
12737 return Error(E);
12738 CharUnits Size = Info.Ctx.getTypeSizeInChars(BaseTy);
12739 uint64_t OffsetLimit = Size.getQuantity();
12740 if (CompareLHS > OffsetLimit || CompareRHS > OffsetLimit)
12741 return Error(E);
12742 }
12743
12744 if (CompareLHS < CompareRHS)
12745 return Success(CmpResult::Less, E);
12746 if (CompareLHS > CompareRHS)
12747 return Success(CmpResult::Greater, E);
12748 return Success(CmpResult::Equal, E);
12749 }
12750
12751 if (LHSTy->isMemberPointerType()) {
12752 assert(IsEquality && "unexpected member pointer operation");
12753 assert(RHSTy->isMemberPointerType() && "invalid comparison");
12754
12755 MemberPtr LHSValue, RHSValue;
12756
12757 bool LHSOK = EvaluateMemberPointer(E->getLHS(), LHSValue, Info);
12758 if (!LHSOK && !Info.noteFailure())
12759 return false;
12760
12761 if (!EvaluateMemberPointer(E->getRHS(), RHSValue, Info) || !LHSOK)
12762 return false;
12763
12764 // C++11 [expr.eq]p2:
12765 // If both operands are null, they compare equal. Otherwise if only one is
12766 // null, they compare unequal.
12767 if (!LHSValue.getDecl() || !RHSValue.getDecl()) {
12768 bool Equal = !LHSValue.getDecl() && !RHSValue.getDecl();
12769 return Success(Equal ? CmpResult::Equal : CmpResult::Unequal, E);
12770 }
12771
12772 // Otherwise if either is a pointer to a virtual member function, the
12773 // result is unspecified.
12774 if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(LHSValue.getDecl()))
12775 if (MD->isVirtual())
12776 Info.CCEDiag(E, diag::note_constexpr_compare_virtual_mem_ptr) << MD;
12777 if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(RHSValue.getDecl()))
12778 if (MD->isVirtual())
12779 Info.CCEDiag(E, diag::note_constexpr_compare_virtual_mem_ptr) << MD;
12780
12781 // Otherwise they compare equal if and only if they would refer to the
12782 // same member of the same most derived object or the same subobject if
12783 // they were dereferenced with a hypothetical object of the associated
12784 // class type.
12785 bool Equal = LHSValue == RHSValue;
12786 return Success(Equal ? CmpResult::Equal : CmpResult::Unequal, E);
12787 }
12788
12789 if (LHSTy->isNullPtrType()) {
12790 assert(E->isComparisonOp() && "unexpected nullptr operation");
12791 assert(RHSTy->isNullPtrType() && "missing pointer conversion");
12792 // C++11 [expr.rel]p4, [expr.eq]p3: If two operands of type std::nullptr_t
12793 // are compared, the result is true of the operator is <=, >= or ==, and
12794 // false otherwise.
12795 return Success(CmpResult::Equal, E);
12796 }
12797
12798 return DoAfter();
12799 }
12800
VisitBinCmp(const BinaryOperator * E)12801 bool RecordExprEvaluator::VisitBinCmp(const BinaryOperator *E) {
12802 if (!CheckLiteralType(Info, E))
12803 return false;
12804
12805 auto OnSuccess = [&](CmpResult CR, const BinaryOperator *E) {
12806 ComparisonCategoryResult CCR;
12807 switch (CR) {
12808 case CmpResult::Unequal:
12809 llvm_unreachable("should never produce Unequal for three-way comparison");
12810 case CmpResult::Less:
12811 CCR = ComparisonCategoryResult::Less;
12812 break;
12813 case CmpResult::Equal:
12814 CCR = ComparisonCategoryResult::Equal;
12815 break;
12816 case CmpResult::Greater:
12817 CCR = ComparisonCategoryResult::Greater;
12818 break;
12819 case CmpResult::Unordered:
12820 CCR = ComparisonCategoryResult::Unordered;
12821 break;
12822 }
12823 // Evaluation succeeded. Lookup the information for the comparison category
12824 // type and fetch the VarDecl for the result.
12825 const ComparisonCategoryInfo &CmpInfo =
12826 Info.Ctx.CompCategories.getInfoForType(E->getType());
12827 const VarDecl *VD = CmpInfo.getValueInfo(CmpInfo.makeWeakResult(CCR))->VD;
12828 // Check and evaluate the result as a constant expression.
12829 LValue LV;
12830 LV.set(VD);
12831 if (!handleLValueToRValueConversion(Info, E, E->getType(), LV, Result))
12832 return false;
12833 return CheckConstantExpression(Info, E->getExprLoc(), E->getType(), Result,
12834 ConstantExprKind::Normal);
12835 };
12836 return EvaluateComparisonBinaryOperator(Info, E, OnSuccess, [&]() {
12837 return ExprEvaluatorBaseTy::VisitBinCmp(E);
12838 });
12839 }
12840
VisitBinaryOperator(const BinaryOperator * E)12841 bool IntExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
12842 // We don't support assignment in C. C++ assignments don't get here because
12843 // assignment is an lvalue in C++.
12844 if (E->isAssignmentOp()) {
12845 Error(E);
12846 if (!Info.noteFailure())
12847 return false;
12848 }
12849
12850 if (DataRecursiveIntBinOpEvaluator::shouldEnqueue(E))
12851 return DataRecursiveIntBinOpEvaluator(*this, Result).Traverse(E);
12852
12853 assert((!E->getLHS()->getType()->isIntegralOrEnumerationType() ||
12854 !E->getRHS()->getType()->isIntegralOrEnumerationType()) &&
12855 "DataRecursiveIntBinOpEvaluator should have handled integral types");
12856
12857 if (E->isComparisonOp()) {
12858 // Evaluate builtin binary comparisons by evaluating them as three-way
12859 // comparisons and then translating the result.
12860 auto OnSuccess = [&](CmpResult CR, const BinaryOperator *E) {
12861 assert((CR != CmpResult::Unequal || E->isEqualityOp()) &&
12862 "should only produce Unequal for equality comparisons");
12863 bool IsEqual = CR == CmpResult::Equal,
12864 IsLess = CR == CmpResult::Less,
12865 IsGreater = CR == CmpResult::Greater;
12866 auto Op = E->getOpcode();
12867 switch (Op) {
12868 default:
12869 llvm_unreachable("unsupported binary operator");
12870 case BO_EQ:
12871 case BO_NE:
12872 return Success(IsEqual == (Op == BO_EQ), E);
12873 case BO_LT:
12874 return Success(IsLess, E);
12875 case BO_GT:
12876 return Success(IsGreater, E);
12877 case BO_LE:
12878 return Success(IsEqual || IsLess, E);
12879 case BO_GE:
12880 return Success(IsEqual || IsGreater, E);
12881 }
12882 };
12883 return EvaluateComparisonBinaryOperator(Info, E, OnSuccess, [&]() {
12884 return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
12885 });
12886 }
12887
12888 QualType LHSTy = E->getLHS()->getType();
12889 QualType RHSTy = E->getRHS()->getType();
12890
12891 if (LHSTy->isPointerType() && RHSTy->isPointerType() &&
12892 E->getOpcode() == BO_Sub) {
12893 LValue LHSValue, RHSValue;
12894
12895 bool LHSOK = EvaluatePointer(E->getLHS(), LHSValue, Info);
12896 if (!LHSOK && !Info.noteFailure())
12897 return false;
12898
12899 if (!EvaluatePointer(E->getRHS(), RHSValue, Info) || !LHSOK)
12900 return false;
12901
12902 // Reject differing bases from the normal codepath; we special-case
12903 // comparisons to null.
12904 if (!HasSameBase(LHSValue, RHSValue)) {
12905 // Handle &&A - &&B.
12906 if (!LHSValue.Offset.isZero() || !RHSValue.Offset.isZero())
12907 return Error(E);
12908 const Expr *LHSExpr = LHSValue.Base.dyn_cast<const Expr *>();
12909 const Expr *RHSExpr = RHSValue.Base.dyn_cast<const Expr *>();
12910 if (!LHSExpr || !RHSExpr)
12911 return Error(E);
12912 const AddrLabelExpr *LHSAddrExpr = dyn_cast<AddrLabelExpr>(LHSExpr);
12913 const AddrLabelExpr *RHSAddrExpr = dyn_cast<AddrLabelExpr>(RHSExpr);
12914 if (!LHSAddrExpr || !RHSAddrExpr)
12915 return Error(E);
12916 // Make sure both labels come from the same function.
12917 if (LHSAddrExpr->getLabel()->getDeclContext() !=
12918 RHSAddrExpr->getLabel()->getDeclContext())
12919 return Error(E);
12920 return Success(APValue(LHSAddrExpr, RHSAddrExpr), E);
12921 }
12922 const CharUnits &LHSOffset = LHSValue.getLValueOffset();
12923 const CharUnits &RHSOffset = RHSValue.getLValueOffset();
12924
12925 SubobjectDesignator &LHSDesignator = LHSValue.getLValueDesignator();
12926 SubobjectDesignator &RHSDesignator = RHSValue.getLValueDesignator();
12927
12928 // C++11 [expr.add]p6:
12929 // Unless both pointers point to elements of the same array object, or
12930 // one past the last element of the array object, the behavior is
12931 // undefined.
12932 if (!LHSDesignator.Invalid && !RHSDesignator.Invalid &&
12933 !AreElementsOfSameArray(getType(LHSValue.Base), LHSDesignator,
12934 RHSDesignator))
12935 Info.CCEDiag(E, diag::note_constexpr_pointer_subtraction_not_same_array);
12936
12937 QualType Type = E->getLHS()->getType();
12938 QualType ElementType = Type->castAs<PointerType>()->getPointeeType();
12939
12940 CharUnits ElementSize;
12941 if (!HandleSizeof(Info, E->getExprLoc(), ElementType, ElementSize))
12942 return false;
12943
12944 // As an extension, a type may have zero size (empty struct or union in
12945 // C, array of zero length). Pointer subtraction in such cases has
12946 // undefined behavior, so is not constant.
12947 if (ElementSize.isZero()) {
12948 Info.FFDiag(E, diag::note_constexpr_pointer_subtraction_zero_size)
12949 << ElementType;
12950 return false;
12951 }
12952
12953 // FIXME: LLVM and GCC both compute LHSOffset - RHSOffset at runtime,
12954 // and produce incorrect results when it overflows. Such behavior
12955 // appears to be non-conforming, but is common, so perhaps we should
12956 // assume the standard intended for such cases to be undefined behavior
12957 // and check for them.
12958
12959 // Compute (LHSOffset - RHSOffset) / Size carefully, checking for
12960 // overflow in the final conversion to ptrdiff_t.
12961 APSInt LHS(llvm::APInt(65, (int64_t)LHSOffset.getQuantity(), true), false);
12962 APSInt RHS(llvm::APInt(65, (int64_t)RHSOffset.getQuantity(), true), false);
12963 APSInt ElemSize(llvm::APInt(65, (int64_t)ElementSize.getQuantity(), true),
12964 false);
12965 APSInt TrueResult = (LHS - RHS) / ElemSize;
12966 APSInt Result = TrueResult.trunc(Info.Ctx.getIntWidth(E->getType()));
12967
12968 if (Result.extend(65) != TrueResult &&
12969 !HandleOverflow(Info, E, TrueResult, E->getType()))
12970 return false;
12971 return Success(Result, E);
12972 }
12973
12974 return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
12975 }
12976
12977 /// VisitUnaryExprOrTypeTraitExpr - Evaluate a sizeof, alignof or vec_step with
12978 /// a result as the expression's type.
VisitUnaryExprOrTypeTraitExpr(const UnaryExprOrTypeTraitExpr * E)12979 bool IntExprEvaluator::VisitUnaryExprOrTypeTraitExpr(
12980 const UnaryExprOrTypeTraitExpr *E) {
12981 switch(E->getKind()) {
12982 case UETT_PreferredAlignOf:
12983 case UETT_AlignOf: {
12984 if (E->isArgumentType())
12985 return Success(GetAlignOfType(Info, E->getArgumentType(), E->getKind()),
12986 E);
12987 else
12988 return Success(GetAlignOfExpr(Info, E->getArgumentExpr(), E->getKind()),
12989 E);
12990 }
12991
12992 case UETT_VecStep: {
12993 QualType Ty = E->getTypeOfArgument();
12994
12995 if (Ty->isVectorType()) {
12996 unsigned n = Ty->castAs<VectorType>()->getNumElements();
12997
12998 // The vec_step built-in functions that take a 3-component
12999 // vector return 4. (OpenCL 1.1 spec 6.11.12)
13000 if (n == 3)
13001 n = 4;
13002
13003 return Success(n, E);
13004 } else
13005 return Success(1, E);
13006 }
13007
13008 case UETT_SizeOf: {
13009 QualType SrcTy = E->getTypeOfArgument();
13010 // C++ [expr.sizeof]p2: "When applied to a reference or a reference type,
13011 // the result is the size of the referenced type."
13012 if (const ReferenceType *Ref = SrcTy->getAs<ReferenceType>())
13013 SrcTy = Ref->getPointeeType();
13014
13015 CharUnits Sizeof;
13016 if (!HandleSizeof(Info, E->getExprLoc(), SrcTy, Sizeof))
13017 return false;
13018 return Success(Sizeof, E);
13019 }
13020 case UETT_OpenMPRequiredSimdAlign:
13021 assert(E->isArgumentType());
13022 return Success(
13023 Info.Ctx.toCharUnitsFromBits(
13024 Info.Ctx.getOpenMPDefaultSimdAlign(E->getArgumentType()))
13025 .getQuantity(),
13026 E);
13027 }
13028
13029 llvm_unreachable("unknown expr/type trait");
13030 }
13031
VisitOffsetOfExpr(const OffsetOfExpr * OOE)13032 bool IntExprEvaluator::VisitOffsetOfExpr(const OffsetOfExpr *OOE) {
13033 CharUnits Result;
13034 unsigned n = OOE->getNumComponents();
13035 if (n == 0)
13036 return Error(OOE);
13037 QualType CurrentType = OOE->getTypeSourceInfo()->getType();
13038 for (unsigned i = 0; i != n; ++i) {
13039 OffsetOfNode ON = OOE->getComponent(i);
13040 switch (ON.getKind()) {
13041 case OffsetOfNode::Array: {
13042 const Expr *Idx = OOE->getIndexExpr(ON.getArrayExprIndex());
13043 APSInt IdxResult;
13044 if (!EvaluateInteger(Idx, IdxResult, Info))
13045 return false;
13046 const ArrayType *AT = Info.Ctx.getAsArrayType(CurrentType);
13047 if (!AT)
13048 return Error(OOE);
13049 CurrentType = AT->getElementType();
13050 CharUnits ElementSize = Info.Ctx.getTypeSizeInChars(CurrentType);
13051 Result += IdxResult.getSExtValue() * ElementSize;
13052 break;
13053 }
13054
13055 case OffsetOfNode::Field: {
13056 FieldDecl *MemberDecl = ON.getField();
13057 const RecordType *RT = CurrentType->getAs<RecordType>();
13058 if (!RT)
13059 return Error(OOE);
13060 RecordDecl *RD = RT->getDecl();
13061 if (RD->isInvalidDecl()) return false;
13062 const ASTRecordLayout &RL = Info.Ctx.getASTRecordLayout(RD);
13063 unsigned i = MemberDecl->getFieldIndex();
13064 assert(i < RL.getFieldCount() && "offsetof field in wrong type");
13065 Result += Info.Ctx.toCharUnitsFromBits(RL.getFieldOffset(i));
13066 CurrentType = MemberDecl->getType().getNonReferenceType();
13067 break;
13068 }
13069
13070 case OffsetOfNode::Identifier:
13071 llvm_unreachable("dependent __builtin_offsetof");
13072
13073 case OffsetOfNode::Base: {
13074 CXXBaseSpecifier *BaseSpec = ON.getBase();
13075 if (BaseSpec->isVirtual())
13076 return Error(OOE);
13077
13078 // Find the layout of the class whose base we are looking into.
13079 const RecordType *RT = CurrentType->getAs<RecordType>();
13080 if (!RT)
13081 return Error(OOE);
13082 RecordDecl *RD = RT->getDecl();
13083 if (RD->isInvalidDecl()) return false;
13084 const ASTRecordLayout &RL = Info.Ctx.getASTRecordLayout(RD);
13085
13086 // Find the base class itself.
13087 CurrentType = BaseSpec->getType();
13088 const RecordType *BaseRT = CurrentType->getAs<RecordType>();
13089 if (!BaseRT)
13090 return Error(OOE);
13091
13092 // Add the offset to the base.
13093 Result += RL.getBaseClassOffset(cast<CXXRecordDecl>(BaseRT->getDecl()));
13094 break;
13095 }
13096 }
13097 }
13098 return Success(Result, OOE);
13099 }
13100
VisitUnaryOperator(const UnaryOperator * E)13101 bool IntExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) {
13102 switch (E->getOpcode()) {
13103 default:
13104 // Address, indirect, pre/post inc/dec, etc are not valid constant exprs.
13105 // See C99 6.6p3.
13106 return Error(E);
13107 case UO_Extension:
13108 // FIXME: Should extension allow i-c-e extension expressions in its scope?
13109 // If so, we could clear the diagnostic ID.
13110 return Visit(E->getSubExpr());
13111 case UO_Plus:
13112 // The result is just the value.
13113 return Visit(E->getSubExpr());
13114 case UO_Minus: {
13115 if (!Visit(E->getSubExpr()))
13116 return false;
13117 if (!Result.isInt()) return Error(E);
13118 const APSInt &Value = Result.getInt();
13119 if (Value.isSigned() && Value.isMinSignedValue() && E->canOverflow() &&
13120 !HandleOverflow(Info, E, -Value.extend(Value.getBitWidth() + 1),
13121 E->getType()))
13122 return false;
13123 return Success(-Value, E);
13124 }
13125 case UO_Not: {
13126 if (!Visit(E->getSubExpr()))
13127 return false;
13128 if (!Result.isInt()) return Error(E);
13129 return Success(~Result.getInt(), E);
13130 }
13131 case UO_LNot: {
13132 bool bres;
13133 if (!EvaluateAsBooleanCondition(E->getSubExpr(), bres, Info))
13134 return false;
13135 return Success(!bres, E);
13136 }
13137 }
13138 }
13139
13140 /// HandleCast - This is used to evaluate implicit or explicit casts where the
13141 /// result type is integer.
VisitCastExpr(const CastExpr * E)13142 bool IntExprEvaluator::VisitCastExpr(const CastExpr *E) {
13143 const Expr *SubExpr = E->getSubExpr();
13144 QualType DestType = E->getType();
13145 QualType SrcType = SubExpr->getType();
13146
13147 switch (E->getCastKind()) {
13148 case CK_BaseToDerived:
13149 case CK_DerivedToBase:
13150 case CK_UncheckedDerivedToBase:
13151 case CK_Dynamic:
13152 case CK_ToUnion:
13153 case CK_ArrayToPointerDecay:
13154 case CK_FunctionToPointerDecay:
13155 case CK_NullToPointer:
13156 case CK_NullToMemberPointer:
13157 case CK_BaseToDerivedMemberPointer:
13158 case CK_DerivedToBaseMemberPointer:
13159 case CK_ReinterpretMemberPointer:
13160 case CK_ConstructorConversion:
13161 case CK_IntegralToPointer:
13162 case CK_ToVoid:
13163 case CK_VectorSplat:
13164 case CK_IntegralToFloating:
13165 case CK_FloatingCast:
13166 case CK_CPointerToObjCPointerCast:
13167 case CK_BlockPointerToObjCPointerCast:
13168 case CK_AnyPointerToBlockPointerCast:
13169 case CK_ObjCObjectLValueCast:
13170 case CK_FloatingRealToComplex:
13171 case CK_FloatingComplexToReal:
13172 case CK_FloatingComplexCast:
13173 case CK_FloatingComplexToIntegralComplex:
13174 case CK_IntegralRealToComplex:
13175 case CK_IntegralComplexCast:
13176 case CK_IntegralComplexToFloatingComplex:
13177 case CK_BuiltinFnToFnPtr:
13178 case CK_ZeroToOCLOpaqueType:
13179 case CK_NonAtomicToAtomic:
13180 case CK_AddressSpaceConversion:
13181 case CK_IntToOCLSampler:
13182 case CK_FloatingToFixedPoint:
13183 case CK_FixedPointToFloating:
13184 case CK_FixedPointCast:
13185 case CK_IntegralToFixedPoint:
13186 case CK_MatrixCast:
13187 llvm_unreachable("invalid cast kind for integral value");
13188
13189 case CK_BitCast:
13190 case CK_Dependent:
13191 case CK_LValueBitCast:
13192 case CK_ARCProduceObject:
13193 case CK_ARCConsumeObject:
13194 case CK_ARCReclaimReturnedObject:
13195 case CK_ARCExtendBlockObject:
13196 case CK_CopyAndAutoreleaseBlockObject:
13197 return Error(E);
13198
13199 case CK_UserDefinedConversion:
13200 case CK_LValueToRValue:
13201 case CK_AtomicToNonAtomic:
13202 case CK_NoOp:
13203 case CK_LValueToRValueBitCast:
13204 return ExprEvaluatorBaseTy::VisitCastExpr(E);
13205
13206 case CK_MemberPointerToBoolean:
13207 case CK_PointerToBoolean:
13208 case CK_IntegralToBoolean:
13209 case CK_FloatingToBoolean:
13210 case CK_BooleanToSignedIntegral:
13211 case CK_FloatingComplexToBoolean:
13212 case CK_IntegralComplexToBoolean: {
13213 bool BoolResult;
13214 if (!EvaluateAsBooleanCondition(SubExpr, BoolResult, Info))
13215 return false;
13216 uint64_t IntResult = BoolResult;
13217 if (BoolResult && E->getCastKind() == CK_BooleanToSignedIntegral)
13218 IntResult = (uint64_t)-1;
13219 return Success(IntResult, E);
13220 }
13221
13222 case CK_FixedPointToIntegral: {
13223 APFixedPoint Src(Info.Ctx.getFixedPointSemantics(SrcType));
13224 if (!EvaluateFixedPoint(SubExpr, Src, Info))
13225 return false;
13226 bool Overflowed;
13227 llvm::APSInt Result = Src.convertToInt(
13228 Info.Ctx.getIntWidth(DestType),
13229 DestType->isSignedIntegerOrEnumerationType(), &Overflowed);
13230 if (Overflowed && !HandleOverflow(Info, E, Result, DestType))
13231 return false;
13232 return Success(Result, E);
13233 }
13234
13235 case CK_FixedPointToBoolean: {
13236 // Unsigned padding does not affect this.
13237 APValue Val;
13238 if (!Evaluate(Val, Info, SubExpr))
13239 return false;
13240 return Success(Val.getFixedPoint().getBoolValue(), E);
13241 }
13242
13243 case CK_IntegralCast: {
13244 if (!Visit(SubExpr))
13245 return false;
13246
13247 if (!Result.isInt()) {
13248 // Allow casts of address-of-label differences if they are no-ops
13249 // or narrowing. (The narrowing case isn't actually guaranteed to
13250 // be constant-evaluatable except in some narrow cases which are hard
13251 // to detect here. We let it through on the assumption the user knows
13252 // what they are doing.)
13253 if (Result.isAddrLabelDiff())
13254 return Info.Ctx.getTypeSize(DestType) <= Info.Ctx.getTypeSize(SrcType);
13255 // Only allow casts of lvalues if they are lossless.
13256 return Info.Ctx.getTypeSize(DestType) == Info.Ctx.getTypeSize(SrcType);
13257 }
13258
13259 return Success(HandleIntToIntCast(Info, E, DestType, SrcType,
13260 Result.getInt()), E);
13261 }
13262
13263 case CK_PointerToIntegral: {
13264 CCEDiag(E, diag::note_constexpr_invalid_cast) << 2;
13265
13266 LValue LV;
13267 if (!EvaluatePointer(SubExpr, LV, Info))
13268 return false;
13269
13270 if (LV.getLValueBase()) {
13271 // Only allow based lvalue casts if they are lossless.
13272 // FIXME: Allow a larger integer size than the pointer size, and allow
13273 // narrowing back down to pointer width in subsequent integral casts.
13274 // FIXME: Check integer type's active bits, not its type size.
13275 if (Info.Ctx.getTypeSize(DestType) != Info.Ctx.getTypeSize(SrcType))
13276 return Error(E);
13277
13278 LV.Designator.setInvalid();
13279 LV.moveInto(Result);
13280 return true;
13281 }
13282
13283 APSInt AsInt;
13284 APValue V;
13285 LV.moveInto(V);
13286 if (!V.toIntegralConstant(AsInt, SrcType, Info.Ctx))
13287 llvm_unreachable("Can't cast this!");
13288
13289 return Success(HandleIntToIntCast(Info, E, DestType, SrcType, AsInt), E);
13290 }
13291
13292 case CK_IntegralComplexToReal: {
13293 ComplexValue C;
13294 if (!EvaluateComplex(SubExpr, C, Info))
13295 return false;
13296 return Success(C.getComplexIntReal(), E);
13297 }
13298
13299 case CK_FloatingToIntegral: {
13300 APFloat F(0.0);
13301 if (!EvaluateFloat(SubExpr, F, Info))
13302 return false;
13303
13304 APSInt Value;
13305 if (!HandleFloatToIntCast(Info, E, SrcType, F, DestType, Value))
13306 return false;
13307 return Success(Value, E);
13308 }
13309 }
13310
13311 llvm_unreachable("unknown cast resulting in integral value");
13312 }
13313
VisitUnaryReal(const UnaryOperator * E)13314 bool IntExprEvaluator::VisitUnaryReal(const UnaryOperator *E) {
13315 if (E->getSubExpr()->getType()->isAnyComplexType()) {
13316 ComplexValue LV;
13317 if (!EvaluateComplex(E->getSubExpr(), LV, Info))
13318 return false;
13319 if (!LV.isComplexInt())
13320 return Error(E);
13321 return Success(LV.getComplexIntReal(), E);
13322 }
13323
13324 return Visit(E->getSubExpr());
13325 }
13326
VisitUnaryImag(const UnaryOperator * E)13327 bool IntExprEvaluator::VisitUnaryImag(const UnaryOperator *E) {
13328 if (E->getSubExpr()->getType()->isComplexIntegerType()) {
13329 ComplexValue LV;
13330 if (!EvaluateComplex(E->getSubExpr(), LV, Info))
13331 return false;
13332 if (!LV.isComplexInt())
13333 return Error(E);
13334 return Success(LV.getComplexIntImag(), E);
13335 }
13336
13337 VisitIgnoredValue(E->getSubExpr());
13338 return Success(0, E);
13339 }
13340
VisitSizeOfPackExpr(const SizeOfPackExpr * E)13341 bool IntExprEvaluator::VisitSizeOfPackExpr(const SizeOfPackExpr *E) {
13342 return Success(E->getPackLength(), E);
13343 }
13344
VisitCXXNoexceptExpr(const CXXNoexceptExpr * E)13345 bool IntExprEvaluator::VisitCXXNoexceptExpr(const CXXNoexceptExpr *E) {
13346 return Success(E->getValue(), E);
13347 }
13348
VisitConceptSpecializationExpr(const ConceptSpecializationExpr * E)13349 bool IntExprEvaluator::VisitConceptSpecializationExpr(
13350 const ConceptSpecializationExpr *E) {
13351 return Success(E->isSatisfied(), E);
13352 }
13353
VisitRequiresExpr(const RequiresExpr * E)13354 bool IntExprEvaluator::VisitRequiresExpr(const RequiresExpr *E) {
13355 return Success(E->isSatisfied(), E);
13356 }
13357
VisitUnaryOperator(const UnaryOperator * E)13358 bool FixedPointExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) {
13359 switch (E->getOpcode()) {
13360 default:
13361 // Invalid unary operators
13362 return Error(E);
13363 case UO_Plus:
13364 // The result is just the value.
13365 return Visit(E->getSubExpr());
13366 case UO_Minus: {
13367 if (!Visit(E->getSubExpr())) return false;
13368 if (!Result.isFixedPoint())
13369 return Error(E);
13370 bool Overflowed;
13371 APFixedPoint Negated = Result.getFixedPoint().negate(&Overflowed);
13372 if (Overflowed && !HandleOverflow(Info, E, Negated, E->getType()))
13373 return false;
13374 return Success(Negated, E);
13375 }
13376 case UO_LNot: {
13377 bool bres;
13378 if (!EvaluateAsBooleanCondition(E->getSubExpr(), bres, Info))
13379 return false;
13380 return Success(!bres, E);
13381 }
13382 }
13383 }
13384
VisitCastExpr(const CastExpr * E)13385 bool FixedPointExprEvaluator::VisitCastExpr(const CastExpr *E) {
13386 const Expr *SubExpr = E->getSubExpr();
13387 QualType DestType = E->getType();
13388 assert(DestType->isFixedPointType() &&
13389 "Expected destination type to be a fixed point type");
13390 auto DestFXSema = Info.Ctx.getFixedPointSemantics(DestType);
13391
13392 switch (E->getCastKind()) {
13393 case CK_FixedPointCast: {
13394 APFixedPoint Src(Info.Ctx.getFixedPointSemantics(SubExpr->getType()));
13395 if (!EvaluateFixedPoint(SubExpr, Src, Info))
13396 return false;
13397 bool Overflowed;
13398 APFixedPoint Result = Src.convert(DestFXSema, &Overflowed);
13399 if (Overflowed) {
13400 if (Info.checkingForUndefinedBehavior())
13401 Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
13402 diag::warn_fixedpoint_constant_overflow)
13403 << Result.toString() << E->getType();
13404 if (!HandleOverflow(Info, E, Result, E->getType()))
13405 return false;
13406 }
13407 return Success(Result, E);
13408 }
13409 case CK_IntegralToFixedPoint: {
13410 APSInt Src;
13411 if (!EvaluateInteger(SubExpr, Src, Info))
13412 return false;
13413
13414 bool Overflowed;
13415 APFixedPoint IntResult = APFixedPoint::getFromIntValue(
13416 Src, Info.Ctx.getFixedPointSemantics(DestType), &Overflowed);
13417
13418 if (Overflowed) {
13419 if (Info.checkingForUndefinedBehavior())
13420 Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
13421 diag::warn_fixedpoint_constant_overflow)
13422 << IntResult.toString() << E->getType();
13423 if (!HandleOverflow(Info, E, IntResult, E->getType()))
13424 return false;
13425 }
13426
13427 return Success(IntResult, E);
13428 }
13429 case CK_FloatingToFixedPoint: {
13430 APFloat Src(0.0);
13431 if (!EvaluateFloat(SubExpr, Src, Info))
13432 return false;
13433
13434 bool Overflowed;
13435 APFixedPoint Result = APFixedPoint::getFromFloatValue(
13436 Src, Info.Ctx.getFixedPointSemantics(DestType), &Overflowed);
13437
13438 if (Overflowed) {
13439 if (Info.checkingForUndefinedBehavior())
13440 Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
13441 diag::warn_fixedpoint_constant_overflow)
13442 << Result.toString() << E->getType();
13443 if (!HandleOverflow(Info, E, Result, E->getType()))
13444 return false;
13445 }
13446
13447 return Success(Result, E);
13448 }
13449 case CK_NoOp:
13450 case CK_LValueToRValue:
13451 return ExprEvaluatorBaseTy::VisitCastExpr(E);
13452 default:
13453 return Error(E);
13454 }
13455 }
13456
VisitBinaryOperator(const BinaryOperator * E)13457 bool FixedPointExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
13458 if (E->isPtrMemOp() || E->isAssignmentOp() || E->getOpcode() == BO_Comma)
13459 return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
13460
13461 const Expr *LHS = E->getLHS();
13462 const Expr *RHS = E->getRHS();
13463 FixedPointSemantics ResultFXSema =
13464 Info.Ctx.getFixedPointSemantics(E->getType());
13465
13466 APFixedPoint LHSFX(Info.Ctx.getFixedPointSemantics(LHS->getType()));
13467 if (!EvaluateFixedPointOrInteger(LHS, LHSFX, Info))
13468 return false;
13469 APFixedPoint RHSFX(Info.Ctx.getFixedPointSemantics(RHS->getType()));
13470 if (!EvaluateFixedPointOrInteger(RHS, RHSFX, Info))
13471 return false;
13472
13473 bool OpOverflow = false, ConversionOverflow = false;
13474 APFixedPoint Result(LHSFX.getSemantics());
13475 switch (E->getOpcode()) {
13476 case BO_Add: {
13477 Result = LHSFX.add(RHSFX, &OpOverflow)
13478 .convert(ResultFXSema, &ConversionOverflow);
13479 break;
13480 }
13481 case BO_Sub: {
13482 Result = LHSFX.sub(RHSFX, &OpOverflow)
13483 .convert(ResultFXSema, &ConversionOverflow);
13484 break;
13485 }
13486 case BO_Mul: {
13487 Result = LHSFX.mul(RHSFX, &OpOverflow)
13488 .convert(ResultFXSema, &ConversionOverflow);
13489 break;
13490 }
13491 case BO_Div: {
13492 if (RHSFX.getValue() == 0) {
13493 Info.FFDiag(E, diag::note_expr_divide_by_zero);
13494 return false;
13495 }
13496 Result = LHSFX.div(RHSFX, &OpOverflow)
13497 .convert(ResultFXSema, &ConversionOverflow);
13498 break;
13499 }
13500 case BO_Shl:
13501 case BO_Shr: {
13502 FixedPointSemantics LHSSema = LHSFX.getSemantics();
13503 llvm::APSInt RHSVal = RHSFX.getValue();
13504
13505 unsigned ShiftBW =
13506 LHSSema.getWidth() - (unsigned)LHSSema.hasUnsignedPadding();
13507 unsigned Amt = RHSVal.getLimitedValue(ShiftBW - 1);
13508 // Embedded-C 4.1.6.2.2:
13509 // The right operand must be nonnegative and less than the total number
13510 // of (nonpadding) bits of the fixed-point operand ...
13511 if (RHSVal.isNegative())
13512 Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHSVal;
13513 else if (Amt != RHSVal)
13514 Info.CCEDiag(E, diag::note_constexpr_large_shift)
13515 << RHSVal << E->getType() << ShiftBW;
13516
13517 if (E->getOpcode() == BO_Shl)
13518 Result = LHSFX.shl(Amt, &OpOverflow);
13519 else
13520 Result = LHSFX.shr(Amt, &OpOverflow);
13521 break;
13522 }
13523 default:
13524 return false;
13525 }
13526 if (OpOverflow || ConversionOverflow) {
13527 if (Info.checkingForUndefinedBehavior())
13528 Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
13529 diag::warn_fixedpoint_constant_overflow)
13530 << Result.toString() << E->getType();
13531 if (!HandleOverflow(Info, E, Result, E->getType()))
13532 return false;
13533 }
13534 return Success(Result, E);
13535 }
13536
13537 //===----------------------------------------------------------------------===//
13538 // Float Evaluation
13539 //===----------------------------------------------------------------------===//
13540
13541 namespace {
13542 class FloatExprEvaluator
13543 : public ExprEvaluatorBase<FloatExprEvaluator> {
13544 APFloat &Result;
13545 public:
FloatExprEvaluator(EvalInfo & info,APFloat & result)13546 FloatExprEvaluator(EvalInfo &info, APFloat &result)
13547 : ExprEvaluatorBaseTy(info), Result(result) {}
13548
Success(const APValue & V,const Expr * e)13549 bool Success(const APValue &V, const Expr *e) {
13550 Result = V.getFloat();
13551 return true;
13552 }
13553
ZeroInitialization(const Expr * E)13554 bool ZeroInitialization(const Expr *E) {
13555 Result = APFloat::getZero(Info.Ctx.getFloatTypeSemantics(E->getType()));
13556 return true;
13557 }
13558
13559 bool VisitCallExpr(const CallExpr *E);
13560
13561 bool VisitUnaryOperator(const UnaryOperator *E);
13562 bool VisitBinaryOperator(const BinaryOperator *E);
13563 bool VisitFloatingLiteral(const FloatingLiteral *E);
13564 bool VisitCastExpr(const CastExpr *E);
13565
13566 bool VisitUnaryReal(const UnaryOperator *E);
13567 bool VisitUnaryImag(const UnaryOperator *E);
13568
13569 // FIXME: Missing: array subscript of vector, member of vector
13570 };
13571 } // end anonymous namespace
13572
EvaluateFloat(const Expr * E,APFloat & Result,EvalInfo & Info)13573 static bool EvaluateFloat(const Expr* E, APFloat& Result, EvalInfo &Info) {
13574 assert(!E->isValueDependent());
13575 assert(E->isRValue() && E->getType()->isRealFloatingType());
13576 return FloatExprEvaluator(Info, Result).Visit(E);
13577 }
13578
TryEvaluateBuiltinNaN(const ASTContext & Context,QualType ResultTy,const Expr * Arg,bool SNaN,llvm::APFloat & Result)13579 static bool TryEvaluateBuiltinNaN(const ASTContext &Context,
13580 QualType ResultTy,
13581 const Expr *Arg,
13582 bool SNaN,
13583 llvm::APFloat &Result) {
13584 const StringLiteral *S = dyn_cast<StringLiteral>(Arg->IgnoreParenCasts());
13585 if (!S) return false;
13586
13587 const llvm::fltSemantics &Sem = Context.getFloatTypeSemantics(ResultTy);
13588
13589 llvm::APInt fill;
13590
13591 // Treat empty strings as if they were zero.
13592 if (S->getString().empty())
13593 fill = llvm::APInt(32, 0);
13594 else if (S->getString().getAsInteger(0, fill))
13595 return false;
13596
13597 if (Context.getTargetInfo().isNan2008()) {
13598 if (SNaN)
13599 Result = llvm::APFloat::getSNaN(Sem, false, &fill);
13600 else
13601 Result = llvm::APFloat::getQNaN(Sem, false, &fill);
13602 } else {
13603 // Prior to IEEE 754-2008, architectures were allowed to choose whether
13604 // the first bit of their significand was set for qNaN or sNaN. MIPS chose
13605 // a different encoding to what became a standard in 2008, and for pre-
13606 // 2008 revisions, MIPS interpreted sNaN-2008 as qNan and qNaN-2008 as
13607 // sNaN. This is now known as "legacy NaN" encoding.
13608 if (SNaN)
13609 Result = llvm::APFloat::getQNaN(Sem, false, &fill);
13610 else
13611 Result = llvm::APFloat::getSNaN(Sem, false, &fill);
13612 }
13613
13614 return true;
13615 }
13616
VisitCallExpr(const CallExpr * E)13617 bool FloatExprEvaluator::VisitCallExpr(const CallExpr *E) {
13618 switch (E->getBuiltinCallee()) {
13619 default:
13620 return ExprEvaluatorBaseTy::VisitCallExpr(E);
13621
13622 case Builtin::BI__builtin_huge_val:
13623 case Builtin::BI__builtin_huge_valf:
13624 case Builtin::BI__builtin_huge_vall:
13625 case Builtin::BI__builtin_huge_valf128:
13626 case Builtin::BI__builtin_inf:
13627 case Builtin::BI__builtin_inff:
13628 case Builtin::BI__builtin_infl:
13629 case Builtin::BI__builtin_inff128: {
13630 const llvm::fltSemantics &Sem =
13631 Info.Ctx.getFloatTypeSemantics(E->getType());
13632 Result = llvm::APFloat::getInf(Sem);
13633 return true;
13634 }
13635
13636 case Builtin::BI__builtin_nans:
13637 case Builtin::BI__builtin_nansf:
13638 case Builtin::BI__builtin_nansl:
13639 case Builtin::BI__builtin_nansf128:
13640 if (!TryEvaluateBuiltinNaN(Info.Ctx, E->getType(), E->getArg(0),
13641 true, Result))
13642 return Error(E);
13643 return true;
13644
13645 case Builtin::BI__builtin_nan:
13646 case Builtin::BI__builtin_nanf:
13647 case Builtin::BI__builtin_nanl:
13648 case Builtin::BI__builtin_nanf128:
13649 // If this is __builtin_nan() turn this into a nan, otherwise we
13650 // can't constant fold it.
13651 if (!TryEvaluateBuiltinNaN(Info.Ctx, E->getType(), E->getArg(0),
13652 false, Result))
13653 return Error(E);
13654 return true;
13655
13656 case Builtin::BI__builtin_fabs:
13657 case Builtin::BI__builtin_fabsf:
13658 case Builtin::BI__builtin_fabsl:
13659 case Builtin::BI__builtin_fabsf128:
13660 // The C standard says "fabs raises no floating-point exceptions,
13661 // even if x is a signaling NaN. The returned value is independent of
13662 // the current rounding direction mode." Therefore constant folding can
13663 // proceed without regard to the floating point settings.
13664 // Reference, WG14 N2478 F.10.4.3
13665 if (!EvaluateFloat(E->getArg(0), Result, Info))
13666 return false;
13667
13668 if (Result.isNegative())
13669 Result.changeSign();
13670 return true;
13671
13672 // FIXME: Builtin::BI__builtin_powi
13673 // FIXME: Builtin::BI__builtin_powif
13674 // FIXME: Builtin::BI__builtin_powil
13675
13676 case Builtin::BI__builtin_copysign:
13677 case Builtin::BI__builtin_copysignf:
13678 case Builtin::BI__builtin_copysignl:
13679 case Builtin::BI__builtin_copysignf128: {
13680 APFloat RHS(0.);
13681 if (!EvaluateFloat(E->getArg(0), Result, Info) ||
13682 !EvaluateFloat(E->getArg(1), RHS, Info))
13683 return false;
13684 Result.copySign(RHS);
13685 return true;
13686 }
13687 }
13688 }
13689
VisitUnaryReal(const UnaryOperator * E)13690 bool FloatExprEvaluator::VisitUnaryReal(const UnaryOperator *E) {
13691 if (E->getSubExpr()->getType()->isAnyComplexType()) {
13692 ComplexValue CV;
13693 if (!EvaluateComplex(E->getSubExpr(), CV, Info))
13694 return false;
13695 Result = CV.FloatReal;
13696 return true;
13697 }
13698
13699 return Visit(E->getSubExpr());
13700 }
13701
VisitUnaryImag(const UnaryOperator * E)13702 bool FloatExprEvaluator::VisitUnaryImag(const UnaryOperator *E) {
13703 if (E->getSubExpr()->getType()->isAnyComplexType()) {
13704 ComplexValue CV;
13705 if (!EvaluateComplex(E->getSubExpr(), CV, Info))
13706 return false;
13707 Result = CV.FloatImag;
13708 return true;
13709 }
13710
13711 VisitIgnoredValue(E->getSubExpr());
13712 const llvm::fltSemantics &Sem = Info.Ctx.getFloatTypeSemantics(E->getType());
13713 Result = llvm::APFloat::getZero(Sem);
13714 return true;
13715 }
13716
VisitUnaryOperator(const UnaryOperator * E)13717 bool FloatExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) {
13718 switch (E->getOpcode()) {
13719 default: return Error(E);
13720 case UO_Plus:
13721 return EvaluateFloat(E->getSubExpr(), Result, Info);
13722 case UO_Minus:
13723 // In C standard, WG14 N2478 F.3 p4
13724 // "the unary - raises no floating point exceptions,
13725 // even if the operand is signalling."
13726 if (!EvaluateFloat(E->getSubExpr(), Result, Info))
13727 return false;
13728 Result.changeSign();
13729 return true;
13730 }
13731 }
13732
VisitBinaryOperator(const BinaryOperator * E)13733 bool FloatExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
13734 if (E->isPtrMemOp() || E->isAssignmentOp() || E->getOpcode() == BO_Comma)
13735 return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
13736
13737 APFloat RHS(0.0);
13738 bool LHSOK = EvaluateFloat(E->getLHS(), Result, Info);
13739 if (!LHSOK && !Info.noteFailure())
13740 return false;
13741 return EvaluateFloat(E->getRHS(), RHS, Info) && LHSOK &&
13742 handleFloatFloatBinOp(Info, E, Result, E->getOpcode(), RHS);
13743 }
13744
VisitFloatingLiteral(const FloatingLiteral * E)13745 bool FloatExprEvaluator::VisitFloatingLiteral(const FloatingLiteral *E) {
13746 Result = E->getValue();
13747 return true;
13748 }
13749
VisitCastExpr(const CastExpr * E)13750 bool FloatExprEvaluator::VisitCastExpr(const CastExpr *E) {
13751 const Expr* SubExpr = E->getSubExpr();
13752
13753 switch (E->getCastKind()) {
13754 default:
13755 return ExprEvaluatorBaseTy::VisitCastExpr(E);
13756
13757 case CK_IntegralToFloating: {
13758 APSInt IntResult;
13759 const FPOptions FPO = E->getFPFeaturesInEffect(
13760 Info.Ctx.getLangOpts());
13761 return EvaluateInteger(SubExpr, IntResult, Info) &&
13762 HandleIntToFloatCast(Info, E, FPO, SubExpr->getType(),
13763 IntResult, E->getType(), Result);
13764 }
13765
13766 case CK_FixedPointToFloating: {
13767 APFixedPoint FixResult(Info.Ctx.getFixedPointSemantics(SubExpr->getType()));
13768 if (!EvaluateFixedPoint(SubExpr, FixResult, Info))
13769 return false;
13770 Result =
13771 FixResult.convertToFloat(Info.Ctx.getFloatTypeSemantics(E->getType()));
13772 return true;
13773 }
13774
13775 case CK_FloatingCast: {
13776 if (!Visit(SubExpr))
13777 return false;
13778 return HandleFloatToFloatCast(Info, E, SubExpr->getType(), E->getType(),
13779 Result);
13780 }
13781
13782 case CK_FloatingComplexToReal: {
13783 ComplexValue V;
13784 if (!EvaluateComplex(SubExpr, V, Info))
13785 return false;
13786 Result = V.getComplexFloatReal();
13787 return true;
13788 }
13789 }
13790 }
13791
13792 //===----------------------------------------------------------------------===//
13793 // Complex Evaluation (for float and integer)
13794 //===----------------------------------------------------------------------===//
13795
13796 namespace {
13797 class ComplexExprEvaluator
13798 : public ExprEvaluatorBase<ComplexExprEvaluator> {
13799 ComplexValue &Result;
13800
13801 public:
ComplexExprEvaluator(EvalInfo & info,ComplexValue & Result)13802 ComplexExprEvaluator(EvalInfo &info, ComplexValue &Result)
13803 : ExprEvaluatorBaseTy(info), Result(Result) {}
13804
Success(const APValue & V,const Expr * e)13805 bool Success(const APValue &V, const Expr *e) {
13806 Result.setFrom(V);
13807 return true;
13808 }
13809
13810 bool ZeroInitialization(const Expr *E);
13811
13812 //===--------------------------------------------------------------------===//
13813 // Visitor Methods
13814 //===--------------------------------------------------------------------===//
13815
13816 bool VisitImaginaryLiteral(const ImaginaryLiteral *E);
13817 bool VisitCastExpr(const CastExpr *E);
13818 bool VisitBinaryOperator(const BinaryOperator *E);
13819 bool VisitUnaryOperator(const UnaryOperator *E);
13820 bool VisitInitListExpr(const InitListExpr *E);
13821 bool VisitCallExpr(const CallExpr *E);
13822 };
13823 } // end anonymous namespace
13824
EvaluateComplex(const Expr * E,ComplexValue & Result,EvalInfo & Info)13825 static bool EvaluateComplex(const Expr *E, ComplexValue &Result,
13826 EvalInfo &Info) {
13827 assert(!E->isValueDependent());
13828 assert(E->isRValue() && E->getType()->isAnyComplexType());
13829 return ComplexExprEvaluator(Info, Result).Visit(E);
13830 }
13831
ZeroInitialization(const Expr * E)13832 bool ComplexExprEvaluator::ZeroInitialization(const Expr *E) {
13833 QualType ElemTy = E->getType()->castAs<ComplexType>()->getElementType();
13834 if (ElemTy->isRealFloatingType()) {
13835 Result.makeComplexFloat();
13836 APFloat Zero = APFloat::getZero(Info.Ctx.getFloatTypeSemantics(ElemTy));
13837 Result.FloatReal = Zero;
13838 Result.FloatImag = Zero;
13839 } else {
13840 Result.makeComplexInt();
13841 APSInt Zero = Info.Ctx.MakeIntValue(0, ElemTy);
13842 Result.IntReal = Zero;
13843 Result.IntImag = Zero;
13844 }
13845 return true;
13846 }
13847
VisitImaginaryLiteral(const ImaginaryLiteral * E)13848 bool ComplexExprEvaluator::VisitImaginaryLiteral(const ImaginaryLiteral *E) {
13849 const Expr* SubExpr = E->getSubExpr();
13850
13851 if (SubExpr->getType()->isRealFloatingType()) {
13852 Result.makeComplexFloat();
13853 APFloat &Imag = Result.FloatImag;
13854 if (!EvaluateFloat(SubExpr, Imag, Info))
13855 return false;
13856
13857 Result.FloatReal = APFloat(Imag.getSemantics());
13858 return true;
13859 } else {
13860 assert(SubExpr->getType()->isIntegerType() &&
13861 "Unexpected imaginary literal.");
13862
13863 Result.makeComplexInt();
13864 APSInt &Imag = Result.IntImag;
13865 if (!EvaluateInteger(SubExpr, Imag, Info))
13866 return false;
13867
13868 Result.IntReal = APSInt(Imag.getBitWidth(), !Imag.isSigned());
13869 return true;
13870 }
13871 }
13872
VisitCastExpr(const CastExpr * E)13873 bool ComplexExprEvaluator::VisitCastExpr(const CastExpr *E) {
13874
13875 switch (E->getCastKind()) {
13876 case CK_BitCast:
13877 case CK_BaseToDerived:
13878 case CK_DerivedToBase:
13879 case CK_UncheckedDerivedToBase:
13880 case CK_Dynamic:
13881 case CK_ToUnion:
13882 case CK_ArrayToPointerDecay:
13883 case CK_FunctionToPointerDecay:
13884 case CK_NullToPointer:
13885 case CK_NullToMemberPointer:
13886 case CK_BaseToDerivedMemberPointer:
13887 case CK_DerivedToBaseMemberPointer:
13888 case CK_MemberPointerToBoolean:
13889 case CK_ReinterpretMemberPointer:
13890 case CK_ConstructorConversion:
13891 case CK_IntegralToPointer:
13892 case CK_PointerToIntegral:
13893 case CK_PointerToBoolean:
13894 case CK_ToVoid:
13895 case CK_VectorSplat:
13896 case CK_IntegralCast:
13897 case CK_BooleanToSignedIntegral:
13898 case CK_IntegralToBoolean:
13899 case CK_IntegralToFloating:
13900 case CK_FloatingToIntegral:
13901 case CK_FloatingToBoolean:
13902 case CK_FloatingCast:
13903 case CK_CPointerToObjCPointerCast:
13904 case CK_BlockPointerToObjCPointerCast:
13905 case CK_AnyPointerToBlockPointerCast:
13906 case CK_ObjCObjectLValueCast:
13907 case CK_FloatingComplexToReal:
13908 case CK_FloatingComplexToBoolean:
13909 case CK_IntegralComplexToReal:
13910 case CK_IntegralComplexToBoolean:
13911 case CK_ARCProduceObject:
13912 case CK_ARCConsumeObject:
13913 case CK_ARCReclaimReturnedObject:
13914 case CK_ARCExtendBlockObject:
13915 case CK_CopyAndAutoreleaseBlockObject:
13916 case CK_BuiltinFnToFnPtr:
13917 case CK_ZeroToOCLOpaqueType:
13918 case CK_NonAtomicToAtomic:
13919 case CK_AddressSpaceConversion:
13920 case CK_IntToOCLSampler:
13921 case CK_FloatingToFixedPoint:
13922 case CK_FixedPointToFloating:
13923 case CK_FixedPointCast:
13924 case CK_FixedPointToBoolean:
13925 case CK_FixedPointToIntegral:
13926 case CK_IntegralToFixedPoint:
13927 case CK_MatrixCast:
13928 llvm_unreachable("invalid cast kind for complex value");
13929
13930 case CK_LValueToRValue:
13931 case CK_AtomicToNonAtomic:
13932 case CK_NoOp:
13933 case CK_LValueToRValueBitCast:
13934 return ExprEvaluatorBaseTy::VisitCastExpr(E);
13935
13936 case CK_Dependent:
13937 case CK_LValueBitCast:
13938 case CK_UserDefinedConversion:
13939 return Error(E);
13940
13941 case CK_FloatingRealToComplex: {
13942 APFloat &Real = Result.FloatReal;
13943 if (!EvaluateFloat(E->getSubExpr(), Real, Info))
13944 return false;
13945
13946 Result.makeComplexFloat();
13947 Result.FloatImag = APFloat(Real.getSemantics());
13948 return true;
13949 }
13950
13951 case CK_FloatingComplexCast: {
13952 if (!Visit(E->getSubExpr()))
13953 return false;
13954
13955 QualType To = E->getType()->castAs<ComplexType>()->getElementType();
13956 QualType From
13957 = E->getSubExpr()->getType()->castAs<ComplexType>()->getElementType();
13958
13959 return HandleFloatToFloatCast(Info, E, From, To, Result.FloatReal) &&
13960 HandleFloatToFloatCast(Info, E, From, To, Result.FloatImag);
13961 }
13962
13963 case CK_FloatingComplexToIntegralComplex: {
13964 if (!Visit(E->getSubExpr()))
13965 return false;
13966
13967 QualType To = E->getType()->castAs<ComplexType>()->getElementType();
13968 QualType From
13969 = E->getSubExpr()->getType()->castAs<ComplexType>()->getElementType();
13970 Result.makeComplexInt();
13971 return HandleFloatToIntCast(Info, E, From, Result.FloatReal,
13972 To, Result.IntReal) &&
13973 HandleFloatToIntCast(Info, E, From, Result.FloatImag,
13974 To, Result.IntImag);
13975 }
13976
13977 case CK_IntegralRealToComplex: {
13978 APSInt &Real = Result.IntReal;
13979 if (!EvaluateInteger(E->getSubExpr(), Real, Info))
13980 return false;
13981
13982 Result.makeComplexInt();
13983 Result.IntImag = APSInt(Real.getBitWidth(), !Real.isSigned());
13984 return true;
13985 }
13986
13987 case CK_IntegralComplexCast: {
13988 if (!Visit(E->getSubExpr()))
13989 return false;
13990
13991 QualType To = E->getType()->castAs<ComplexType>()->getElementType();
13992 QualType From
13993 = E->getSubExpr()->getType()->castAs<ComplexType>()->getElementType();
13994
13995 Result.IntReal = HandleIntToIntCast(Info, E, To, From, Result.IntReal);
13996 Result.IntImag = HandleIntToIntCast(Info, E, To, From, Result.IntImag);
13997 return true;
13998 }
13999
14000 case CK_IntegralComplexToFloatingComplex: {
14001 if (!Visit(E->getSubExpr()))
14002 return false;
14003
14004 const FPOptions FPO = E->getFPFeaturesInEffect(
14005 Info.Ctx.getLangOpts());
14006 QualType To = E->getType()->castAs<ComplexType>()->getElementType();
14007 QualType From
14008 = E->getSubExpr()->getType()->castAs<ComplexType>()->getElementType();
14009 Result.makeComplexFloat();
14010 return HandleIntToFloatCast(Info, E, FPO, From, Result.IntReal,
14011 To, Result.FloatReal) &&
14012 HandleIntToFloatCast(Info, E, FPO, From, Result.IntImag,
14013 To, Result.FloatImag);
14014 }
14015 }
14016
14017 llvm_unreachable("unknown cast resulting in complex value");
14018 }
14019
VisitBinaryOperator(const BinaryOperator * E)14020 bool ComplexExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
14021 if (E->isPtrMemOp() || E->isAssignmentOp() || E->getOpcode() == BO_Comma)
14022 return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
14023
14024 // Track whether the LHS or RHS is real at the type system level. When this is
14025 // the case we can simplify our evaluation strategy.
14026 bool LHSReal = false, RHSReal = false;
14027
14028 bool LHSOK;
14029 if (E->getLHS()->getType()->isRealFloatingType()) {
14030 LHSReal = true;
14031 APFloat &Real = Result.FloatReal;
14032 LHSOK = EvaluateFloat(E->getLHS(), Real, Info);
14033 if (LHSOK) {
14034 Result.makeComplexFloat();
14035 Result.FloatImag = APFloat(Real.getSemantics());
14036 }
14037 } else {
14038 LHSOK = Visit(E->getLHS());
14039 }
14040 if (!LHSOK && !Info.noteFailure())
14041 return false;
14042
14043 ComplexValue RHS;
14044 if (E->getRHS()->getType()->isRealFloatingType()) {
14045 RHSReal = true;
14046 APFloat &Real = RHS.FloatReal;
14047 if (!EvaluateFloat(E->getRHS(), Real, Info) || !LHSOK)
14048 return false;
14049 RHS.makeComplexFloat();
14050 RHS.FloatImag = APFloat(Real.getSemantics());
14051 } else if (!EvaluateComplex(E->getRHS(), RHS, Info) || !LHSOK)
14052 return false;
14053
14054 assert(!(LHSReal && RHSReal) &&
14055 "Cannot have both operands of a complex operation be real.");
14056 switch (E->getOpcode()) {
14057 default: return Error(E);
14058 case BO_Add:
14059 if (Result.isComplexFloat()) {
14060 Result.getComplexFloatReal().add(RHS.getComplexFloatReal(),
14061 APFloat::rmNearestTiesToEven);
14062 if (LHSReal)
14063 Result.getComplexFloatImag() = RHS.getComplexFloatImag();
14064 else if (!RHSReal)
14065 Result.getComplexFloatImag().add(RHS.getComplexFloatImag(),
14066 APFloat::rmNearestTiesToEven);
14067 } else {
14068 Result.getComplexIntReal() += RHS.getComplexIntReal();
14069 Result.getComplexIntImag() += RHS.getComplexIntImag();
14070 }
14071 break;
14072 case BO_Sub:
14073 if (Result.isComplexFloat()) {
14074 Result.getComplexFloatReal().subtract(RHS.getComplexFloatReal(),
14075 APFloat::rmNearestTiesToEven);
14076 if (LHSReal) {
14077 Result.getComplexFloatImag() = RHS.getComplexFloatImag();
14078 Result.getComplexFloatImag().changeSign();
14079 } else if (!RHSReal) {
14080 Result.getComplexFloatImag().subtract(RHS.getComplexFloatImag(),
14081 APFloat::rmNearestTiesToEven);
14082 }
14083 } else {
14084 Result.getComplexIntReal() -= RHS.getComplexIntReal();
14085 Result.getComplexIntImag() -= RHS.getComplexIntImag();
14086 }
14087 break;
14088 case BO_Mul:
14089 if (Result.isComplexFloat()) {
14090 // This is an implementation of complex multiplication according to the
14091 // constraints laid out in C11 Annex G. The implementation uses the
14092 // following naming scheme:
14093 // (a + ib) * (c + id)
14094 ComplexValue LHS = Result;
14095 APFloat &A = LHS.getComplexFloatReal();
14096 APFloat &B = LHS.getComplexFloatImag();
14097 APFloat &C = RHS.getComplexFloatReal();
14098 APFloat &D = RHS.getComplexFloatImag();
14099 APFloat &ResR = Result.getComplexFloatReal();
14100 APFloat &ResI = Result.getComplexFloatImag();
14101 if (LHSReal) {
14102 assert(!RHSReal && "Cannot have two real operands for a complex op!");
14103 ResR = A * C;
14104 ResI = A * D;
14105 } else if (RHSReal) {
14106 ResR = C * A;
14107 ResI = C * B;
14108 } else {
14109 // In the fully general case, we need to handle NaNs and infinities
14110 // robustly.
14111 APFloat AC = A * C;
14112 APFloat BD = B * D;
14113 APFloat AD = A * D;
14114 APFloat BC = B * C;
14115 ResR = AC - BD;
14116 ResI = AD + BC;
14117 if (ResR.isNaN() && ResI.isNaN()) {
14118 bool Recalc = false;
14119 if (A.isInfinity() || B.isInfinity()) {
14120 A = APFloat::copySign(
14121 APFloat(A.getSemantics(), A.isInfinity() ? 1 : 0), A);
14122 B = APFloat::copySign(
14123 APFloat(B.getSemantics(), B.isInfinity() ? 1 : 0), B);
14124 if (C.isNaN())
14125 C = APFloat::copySign(APFloat(C.getSemantics()), C);
14126 if (D.isNaN())
14127 D = APFloat::copySign(APFloat(D.getSemantics()), D);
14128 Recalc = true;
14129 }
14130 if (C.isInfinity() || D.isInfinity()) {
14131 C = APFloat::copySign(
14132 APFloat(C.getSemantics(), C.isInfinity() ? 1 : 0), C);
14133 D = APFloat::copySign(
14134 APFloat(D.getSemantics(), D.isInfinity() ? 1 : 0), D);
14135 if (A.isNaN())
14136 A = APFloat::copySign(APFloat(A.getSemantics()), A);
14137 if (B.isNaN())
14138 B = APFloat::copySign(APFloat(B.getSemantics()), B);
14139 Recalc = true;
14140 }
14141 if (!Recalc && (AC.isInfinity() || BD.isInfinity() ||
14142 AD.isInfinity() || BC.isInfinity())) {
14143 if (A.isNaN())
14144 A = APFloat::copySign(APFloat(A.getSemantics()), A);
14145 if (B.isNaN())
14146 B = APFloat::copySign(APFloat(B.getSemantics()), B);
14147 if (C.isNaN())
14148 C = APFloat::copySign(APFloat(C.getSemantics()), C);
14149 if (D.isNaN())
14150 D = APFloat::copySign(APFloat(D.getSemantics()), D);
14151 Recalc = true;
14152 }
14153 if (Recalc) {
14154 ResR = APFloat::getInf(A.getSemantics()) * (A * C - B * D);
14155 ResI = APFloat::getInf(A.getSemantics()) * (A * D + B * C);
14156 }
14157 }
14158 }
14159 } else {
14160 ComplexValue LHS = Result;
14161 Result.getComplexIntReal() =
14162 (LHS.getComplexIntReal() * RHS.getComplexIntReal() -
14163 LHS.getComplexIntImag() * RHS.getComplexIntImag());
14164 Result.getComplexIntImag() =
14165 (LHS.getComplexIntReal() * RHS.getComplexIntImag() +
14166 LHS.getComplexIntImag() * RHS.getComplexIntReal());
14167 }
14168 break;
14169 case BO_Div:
14170 if (Result.isComplexFloat()) {
14171 // This is an implementation of complex division according to the
14172 // constraints laid out in C11 Annex G. The implementation uses the
14173 // following naming scheme:
14174 // (a + ib) / (c + id)
14175 ComplexValue LHS = Result;
14176 APFloat &A = LHS.getComplexFloatReal();
14177 APFloat &B = LHS.getComplexFloatImag();
14178 APFloat &C = RHS.getComplexFloatReal();
14179 APFloat &D = RHS.getComplexFloatImag();
14180 APFloat &ResR = Result.getComplexFloatReal();
14181 APFloat &ResI = Result.getComplexFloatImag();
14182 if (RHSReal) {
14183 ResR = A / C;
14184 ResI = B / C;
14185 } else {
14186 if (LHSReal) {
14187 // No real optimizations we can do here, stub out with zero.
14188 B = APFloat::getZero(A.getSemantics());
14189 }
14190 int DenomLogB = 0;
14191 APFloat MaxCD = maxnum(abs(C), abs(D));
14192 if (MaxCD.isFinite()) {
14193 DenomLogB = ilogb(MaxCD);
14194 C = scalbn(C, -DenomLogB, APFloat::rmNearestTiesToEven);
14195 D = scalbn(D, -DenomLogB, APFloat::rmNearestTiesToEven);
14196 }
14197 APFloat Denom = C * C + D * D;
14198 ResR = scalbn((A * C + B * D) / Denom, -DenomLogB,
14199 APFloat::rmNearestTiesToEven);
14200 ResI = scalbn((B * C - A * D) / Denom, -DenomLogB,
14201 APFloat::rmNearestTiesToEven);
14202 if (ResR.isNaN() && ResI.isNaN()) {
14203 if (Denom.isPosZero() && (!A.isNaN() || !B.isNaN())) {
14204 ResR = APFloat::getInf(ResR.getSemantics(), C.isNegative()) * A;
14205 ResI = APFloat::getInf(ResR.getSemantics(), C.isNegative()) * B;
14206 } else if ((A.isInfinity() || B.isInfinity()) && C.isFinite() &&
14207 D.isFinite()) {
14208 A = APFloat::copySign(
14209 APFloat(A.getSemantics(), A.isInfinity() ? 1 : 0), A);
14210 B = APFloat::copySign(
14211 APFloat(B.getSemantics(), B.isInfinity() ? 1 : 0), B);
14212 ResR = APFloat::getInf(ResR.getSemantics()) * (A * C + B * D);
14213 ResI = APFloat::getInf(ResI.getSemantics()) * (B * C - A * D);
14214 } else if (MaxCD.isInfinity() && A.isFinite() && B.isFinite()) {
14215 C = APFloat::copySign(
14216 APFloat(C.getSemantics(), C.isInfinity() ? 1 : 0), C);
14217 D = APFloat::copySign(
14218 APFloat(D.getSemantics(), D.isInfinity() ? 1 : 0), D);
14219 ResR = APFloat::getZero(ResR.getSemantics()) * (A * C + B * D);
14220 ResI = APFloat::getZero(ResI.getSemantics()) * (B * C - A * D);
14221 }
14222 }
14223 }
14224 } else {
14225 if (RHS.getComplexIntReal() == 0 && RHS.getComplexIntImag() == 0)
14226 return Error(E, diag::note_expr_divide_by_zero);
14227
14228 ComplexValue LHS = Result;
14229 APSInt Den = RHS.getComplexIntReal() * RHS.getComplexIntReal() +
14230 RHS.getComplexIntImag() * RHS.getComplexIntImag();
14231 Result.getComplexIntReal() =
14232 (LHS.getComplexIntReal() * RHS.getComplexIntReal() +
14233 LHS.getComplexIntImag() * RHS.getComplexIntImag()) / Den;
14234 Result.getComplexIntImag() =
14235 (LHS.getComplexIntImag() * RHS.getComplexIntReal() -
14236 LHS.getComplexIntReal() * RHS.getComplexIntImag()) / Den;
14237 }
14238 break;
14239 }
14240
14241 return true;
14242 }
14243
VisitUnaryOperator(const UnaryOperator * E)14244 bool ComplexExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) {
14245 // Get the operand value into 'Result'.
14246 if (!Visit(E->getSubExpr()))
14247 return false;
14248
14249 switch (E->getOpcode()) {
14250 default:
14251 return Error(E);
14252 case UO_Extension:
14253 return true;
14254 case UO_Plus:
14255 // The result is always just the subexpr.
14256 return true;
14257 case UO_Minus:
14258 if (Result.isComplexFloat()) {
14259 Result.getComplexFloatReal().changeSign();
14260 Result.getComplexFloatImag().changeSign();
14261 }
14262 else {
14263 Result.getComplexIntReal() = -Result.getComplexIntReal();
14264 Result.getComplexIntImag() = -Result.getComplexIntImag();
14265 }
14266 return true;
14267 case UO_Not:
14268 if (Result.isComplexFloat())
14269 Result.getComplexFloatImag().changeSign();
14270 else
14271 Result.getComplexIntImag() = -Result.getComplexIntImag();
14272 return true;
14273 }
14274 }
14275
VisitInitListExpr(const InitListExpr * E)14276 bool ComplexExprEvaluator::VisitInitListExpr(const InitListExpr *E) {
14277 if (E->getNumInits() == 2) {
14278 if (E->getType()->isComplexType()) {
14279 Result.makeComplexFloat();
14280 if (!EvaluateFloat(E->getInit(0), Result.FloatReal, Info))
14281 return false;
14282 if (!EvaluateFloat(E->getInit(1), Result.FloatImag, Info))
14283 return false;
14284 } else {
14285 Result.makeComplexInt();
14286 if (!EvaluateInteger(E->getInit(0), Result.IntReal, Info))
14287 return false;
14288 if (!EvaluateInteger(E->getInit(1), Result.IntImag, Info))
14289 return false;
14290 }
14291 return true;
14292 }
14293 return ExprEvaluatorBaseTy::VisitInitListExpr(E);
14294 }
14295
VisitCallExpr(const CallExpr * E)14296 bool ComplexExprEvaluator::VisitCallExpr(const CallExpr *E) {
14297 switch (E->getBuiltinCallee()) {
14298 case Builtin::BI__builtin_complex:
14299 Result.makeComplexFloat();
14300 if (!EvaluateFloat(E->getArg(0), Result.FloatReal, Info))
14301 return false;
14302 if (!EvaluateFloat(E->getArg(1), Result.FloatImag, Info))
14303 return false;
14304 return true;
14305
14306 default:
14307 break;
14308 }
14309
14310 return ExprEvaluatorBaseTy::VisitCallExpr(E);
14311 }
14312
14313 //===----------------------------------------------------------------------===//
14314 // Atomic expression evaluation, essentially just handling the NonAtomicToAtomic
14315 // implicit conversion.
14316 //===----------------------------------------------------------------------===//
14317
14318 namespace {
14319 class AtomicExprEvaluator :
14320 public ExprEvaluatorBase<AtomicExprEvaluator> {
14321 const LValue *This;
14322 APValue &Result;
14323 public:
AtomicExprEvaluator(EvalInfo & Info,const LValue * This,APValue & Result)14324 AtomicExprEvaluator(EvalInfo &Info, const LValue *This, APValue &Result)
14325 : ExprEvaluatorBaseTy(Info), This(This), Result(Result) {}
14326
Success(const APValue & V,const Expr * E)14327 bool Success(const APValue &V, const Expr *E) {
14328 Result = V;
14329 return true;
14330 }
14331
ZeroInitialization(const Expr * E)14332 bool ZeroInitialization(const Expr *E) {
14333 ImplicitValueInitExpr VIE(
14334 E->getType()->castAs<AtomicType>()->getValueType());
14335 // For atomic-qualified class (and array) types in C++, initialize the
14336 // _Atomic-wrapped subobject directly, in-place.
14337 return This ? EvaluateInPlace(Result, Info, *This, &VIE)
14338 : Evaluate(Result, Info, &VIE);
14339 }
14340
VisitCastExpr(const CastExpr * E)14341 bool VisitCastExpr(const CastExpr *E) {
14342 switch (E->getCastKind()) {
14343 default:
14344 return ExprEvaluatorBaseTy::VisitCastExpr(E);
14345 case CK_NonAtomicToAtomic:
14346 return This ? EvaluateInPlace(Result, Info, *This, E->getSubExpr())
14347 : Evaluate(Result, Info, E->getSubExpr());
14348 }
14349 }
14350 };
14351 } // end anonymous namespace
14352
EvaluateAtomic(const Expr * E,const LValue * This,APValue & Result,EvalInfo & Info)14353 static bool EvaluateAtomic(const Expr *E, const LValue *This, APValue &Result,
14354 EvalInfo &Info) {
14355 assert(!E->isValueDependent());
14356 assert(E->isRValue() && E->getType()->isAtomicType());
14357 return AtomicExprEvaluator(Info, This, Result).Visit(E);
14358 }
14359
14360 //===----------------------------------------------------------------------===//
14361 // Void expression evaluation, primarily for a cast to void on the LHS of a
14362 // comma operator
14363 //===----------------------------------------------------------------------===//
14364
14365 namespace {
14366 class VoidExprEvaluator
14367 : public ExprEvaluatorBase<VoidExprEvaluator> {
14368 public:
VoidExprEvaluator(EvalInfo & Info)14369 VoidExprEvaluator(EvalInfo &Info) : ExprEvaluatorBaseTy(Info) {}
14370
Success(const APValue & V,const Expr * e)14371 bool Success(const APValue &V, const Expr *e) { return true; }
14372
ZeroInitialization(const Expr * E)14373 bool ZeroInitialization(const Expr *E) { return true; }
14374
VisitCastExpr(const CastExpr * E)14375 bool VisitCastExpr(const CastExpr *E) {
14376 switch (E->getCastKind()) {
14377 default:
14378 return ExprEvaluatorBaseTy::VisitCastExpr(E);
14379 case CK_ToVoid:
14380 VisitIgnoredValue(E->getSubExpr());
14381 return true;
14382 }
14383 }
14384
VisitCallExpr(const CallExpr * E)14385 bool VisitCallExpr(const CallExpr *E) {
14386 switch (E->getBuiltinCallee()) {
14387 case Builtin::BI__assume:
14388 case Builtin::BI__builtin_assume:
14389 // The argument is not evaluated!
14390 return true;
14391
14392 case Builtin::BI__builtin_operator_delete:
14393 return HandleOperatorDeleteCall(Info, E);
14394
14395 default:
14396 break;
14397 }
14398
14399 return ExprEvaluatorBaseTy::VisitCallExpr(E);
14400 }
14401
14402 bool VisitCXXDeleteExpr(const CXXDeleteExpr *E);
14403 };
14404 } // end anonymous namespace
14405
VisitCXXDeleteExpr(const CXXDeleteExpr * E)14406 bool VoidExprEvaluator::VisitCXXDeleteExpr(const CXXDeleteExpr *E) {
14407 // We cannot speculatively evaluate a delete expression.
14408 if (Info.SpeculativeEvaluationDepth)
14409 return false;
14410
14411 FunctionDecl *OperatorDelete = E->getOperatorDelete();
14412 if (!OperatorDelete->isReplaceableGlobalAllocationFunction()) {
14413 Info.FFDiag(E, diag::note_constexpr_new_non_replaceable)
14414 << isa<CXXMethodDecl>(OperatorDelete) << OperatorDelete;
14415 return false;
14416 }
14417
14418 const Expr *Arg = E->getArgument();
14419
14420 LValue Pointer;
14421 if (!EvaluatePointer(Arg, Pointer, Info))
14422 return false;
14423 if (Pointer.Designator.Invalid)
14424 return false;
14425
14426 // Deleting a null pointer has no effect.
14427 if (Pointer.isNullPointer()) {
14428 // This is the only case where we need to produce an extension warning:
14429 // the only other way we can succeed is if we find a dynamic allocation,
14430 // and we will have warned when we allocated it in that case.
14431 if (!Info.getLangOpts().CPlusPlus20)
14432 Info.CCEDiag(E, diag::note_constexpr_new);
14433 return true;
14434 }
14435
14436 Optional<DynAlloc *> Alloc = CheckDeleteKind(
14437 Info, E, Pointer, E->isArrayForm() ? DynAlloc::ArrayNew : DynAlloc::New);
14438 if (!Alloc)
14439 return false;
14440 QualType AllocType = Pointer.Base.getDynamicAllocType();
14441
14442 // For the non-array case, the designator must be empty if the static type
14443 // does not have a virtual destructor.
14444 if (!E->isArrayForm() && Pointer.Designator.Entries.size() != 0 &&
14445 !hasVirtualDestructor(Arg->getType()->getPointeeType())) {
14446 Info.FFDiag(E, diag::note_constexpr_delete_base_nonvirt_dtor)
14447 << Arg->getType()->getPointeeType() << AllocType;
14448 return false;
14449 }
14450
14451 // For a class type with a virtual destructor, the selected operator delete
14452 // is the one looked up when building the destructor.
14453 if (!E->isArrayForm() && !E->isGlobalDelete()) {
14454 const FunctionDecl *VirtualDelete = getVirtualOperatorDelete(AllocType);
14455 if (VirtualDelete &&
14456 !VirtualDelete->isReplaceableGlobalAllocationFunction()) {
14457 Info.FFDiag(E, diag::note_constexpr_new_non_replaceable)
14458 << isa<CXXMethodDecl>(VirtualDelete) << VirtualDelete;
14459 return false;
14460 }
14461 }
14462
14463 if (!HandleDestruction(Info, E->getExprLoc(), Pointer.getLValueBase(),
14464 (*Alloc)->Value, AllocType))
14465 return false;
14466
14467 if (!Info.HeapAllocs.erase(Pointer.Base.dyn_cast<DynamicAllocLValue>())) {
14468 // The element was already erased. This means the destructor call also
14469 // deleted the object.
14470 // FIXME: This probably results in undefined behavior before we get this
14471 // far, and should be diagnosed elsewhere first.
14472 Info.FFDiag(E, diag::note_constexpr_double_delete);
14473 return false;
14474 }
14475
14476 return true;
14477 }
14478
EvaluateVoid(const Expr * E,EvalInfo & Info)14479 static bool EvaluateVoid(const Expr *E, EvalInfo &Info) {
14480 assert(!E->isValueDependent());
14481 assert(E->isRValue() && E->getType()->isVoidType());
14482 return VoidExprEvaluator(Info).Visit(E);
14483 }
14484
14485 //===----------------------------------------------------------------------===//
14486 // Top level Expr::EvaluateAsRValue method.
14487 //===----------------------------------------------------------------------===//
14488
Evaluate(APValue & Result,EvalInfo & Info,const Expr * E)14489 static bool Evaluate(APValue &Result, EvalInfo &Info, const Expr *E) {
14490 assert(!E->isValueDependent());
14491 // In C, function designators are not lvalues, but we evaluate them as if they
14492 // are.
14493 QualType T = E->getType();
14494 if (E->isGLValue() || T->isFunctionType()) {
14495 LValue LV;
14496 if (!EvaluateLValue(E, LV, Info))
14497 return false;
14498 LV.moveInto(Result);
14499 } else if (T->isVectorType()) {
14500 if (!EvaluateVector(E, Result, Info))
14501 return false;
14502 } else if (T->isIntegralOrEnumerationType()) {
14503 if (!IntExprEvaluator(Info, Result).Visit(E))
14504 return false;
14505 } else if (T->hasPointerRepresentation()) {
14506 LValue LV;
14507 if (!EvaluatePointer(E, LV, Info))
14508 return false;
14509 LV.moveInto(Result);
14510 } else if (T->isRealFloatingType()) {
14511 llvm::APFloat F(0.0);
14512 if (!EvaluateFloat(E, F, Info))
14513 return false;
14514 Result = APValue(F);
14515 } else if (T->isAnyComplexType()) {
14516 ComplexValue C;
14517 if (!EvaluateComplex(E, C, Info))
14518 return false;
14519 C.moveInto(Result);
14520 } else if (T->isFixedPointType()) {
14521 if (!FixedPointExprEvaluator(Info, Result).Visit(E)) return false;
14522 } else if (T->isMemberPointerType()) {
14523 MemberPtr P;
14524 if (!EvaluateMemberPointer(E, P, Info))
14525 return false;
14526 P.moveInto(Result);
14527 return true;
14528 } else if (T->isArrayType()) {
14529 LValue LV;
14530 APValue &Value =
14531 Info.CurrentCall->createTemporary(E, T, ScopeKind::FullExpression, LV);
14532 if (!EvaluateArray(E, LV, Value, Info))
14533 return false;
14534 Result = Value;
14535 } else if (T->isRecordType()) {
14536 LValue LV;
14537 APValue &Value =
14538 Info.CurrentCall->createTemporary(E, T, ScopeKind::FullExpression, LV);
14539 if (!EvaluateRecord(E, LV, Value, Info))
14540 return false;
14541 Result = Value;
14542 } else if (T->isVoidType()) {
14543 if (!Info.getLangOpts().CPlusPlus11)
14544 Info.CCEDiag(E, diag::note_constexpr_nonliteral)
14545 << E->getType();
14546 if (!EvaluateVoid(E, Info))
14547 return false;
14548 } else if (T->isAtomicType()) {
14549 QualType Unqual = T.getAtomicUnqualifiedType();
14550 if (Unqual->isArrayType() || Unqual->isRecordType()) {
14551 LValue LV;
14552 APValue &Value = Info.CurrentCall->createTemporary(
14553 E, Unqual, ScopeKind::FullExpression, LV);
14554 if (!EvaluateAtomic(E, &LV, Value, Info))
14555 return false;
14556 } else {
14557 if (!EvaluateAtomic(E, nullptr, Result, Info))
14558 return false;
14559 }
14560 } else if (Info.getLangOpts().CPlusPlus11) {
14561 Info.FFDiag(E, diag::note_constexpr_nonliteral) << E->getType();
14562 return false;
14563 } else {
14564 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
14565 return false;
14566 }
14567
14568 return true;
14569 }
14570
14571 /// EvaluateInPlace - Evaluate an expression in-place in an APValue. In some
14572 /// cases, the in-place evaluation is essential, since later initializers for
14573 /// an object can indirectly refer to subobjects which were initialized earlier.
EvaluateInPlace(APValue & Result,EvalInfo & Info,const LValue & This,const Expr * E,bool AllowNonLiteralTypes)14574 static bool EvaluateInPlace(APValue &Result, EvalInfo &Info, const LValue &This,
14575 const Expr *E, bool AllowNonLiteralTypes) {
14576 assert(!E->isValueDependent());
14577
14578 if (!AllowNonLiteralTypes && !CheckLiteralType(Info, E, &This))
14579 return false;
14580
14581 if (E->isRValue()) {
14582 // Evaluate arrays and record types in-place, so that later initializers can
14583 // refer to earlier-initialized members of the object.
14584 QualType T = E->getType();
14585 if (T->isArrayType())
14586 return EvaluateArray(E, This, Result, Info);
14587 else if (T->isRecordType())
14588 return EvaluateRecord(E, This, Result, Info);
14589 else if (T->isAtomicType()) {
14590 QualType Unqual = T.getAtomicUnqualifiedType();
14591 if (Unqual->isArrayType() || Unqual->isRecordType())
14592 return EvaluateAtomic(E, &This, Result, Info);
14593 }
14594 }
14595
14596 // For any other type, in-place evaluation is unimportant.
14597 return Evaluate(Result, Info, E);
14598 }
14599
14600 /// EvaluateAsRValue - Try to evaluate this expression, performing an implicit
14601 /// lvalue-to-rvalue cast if it is an lvalue.
EvaluateAsRValue(EvalInfo & Info,const Expr * E,APValue & Result)14602 static bool EvaluateAsRValue(EvalInfo &Info, const Expr *E, APValue &Result) {
14603 assert(!E->isValueDependent());
14604 if (Info.EnableNewConstInterp) {
14605 if (!Info.Ctx.getInterpContext().evaluateAsRValue(Info, E, Result))
14606 return false;
14607 } else {
14608 if (E->getType().isNull())
14609 return false;
14610
14611 if (!CheckLiteralType(Info, E))
14612 return false;
14613
14614 if (!::Evaluate(Result, Info, E))
14615 return false;
14616
14617 if (E->isGLValue()) {
14618 LValue LV;
14619 LV.setFrom(Info.Ctx, Result);
14620 if (!handleLValueToRValueConversion(Info, E, E->getType(), LV, Result))
14621 return false;
14622 }
14623 }
14624
14625 // Check this core constant expression is a constant expression.
14626 return CheckConstantExpression(Info, E->getExprLoc(), E->getType(), Result,
14627 ConstantExprKind::Normal) &&
14628 CheckMemoryLeaks(Info);
14629 }
14630
FastEvaluateAsRValue(const Expr * Exp,Expr::EvalResult & Result,const ASTContext & Ctx,bool & IsConst)14631 static bool FastEvaluateAsRValue(const Expr *Exp, Expr::EvalResult &Result,
14632 const ASTContext &Ctx, bool &IsConst) {
14633 // Fast-path evaluations of integer literals, since we sometimes see files
14634 // containing vast quantities of these.
14635 if (const IntegerLiteral *L = dyn_cast<IntegerLiteral>(Exp)) {
14636 Result.Val = APValue(APSInt(L->getValue(),
14637 L->getType()->isUnsignedIntegerType()));
14638 IsConst = true;
14639 return true;
14640 }
14641
14642 // This case should be rare, but we need to check it before we check on
14643 // the type below.
14644 if (Exp->getType().isNull()) {
14645 IsConst = false;
14646 return true;
14647 }
14648
14649 // FIXME: Evaluating values of large array and record types can cause
14650 // performance problems. Only do so in C++11 for now.
14651 if (Exp->isRValue() && (Exp->getType()->isArrayType() ||
14652 Exp->getType()->isRecordType()) &&
14653 !Ctx.getLangOpts().CPlusPlus11) {
14654 IsConst = false;
14655 return true;
14656 }
14657 return false;
14658 }
14659
hasUnacceptableSideEffect(Expr::EvalStatus & Result,Expr::SideEffectsKind SEK)14660 static bool hasUnacceptableSideEffect(Expr::EvalStatus &Result,
14661 Expr::SideEffectsKind SEK) {
14662 return (SEK < Expr::SE_AllowSideEffects && Result.HasSideEffects) ||
14663 (SEK < Expr::SE_AllowUndefinedBehavior && Result.HasUndefinedBehavior);
14664 }
14665
EvaluateAsRValue(const Expr * E,Expr::EvalResult & Result,const ASTContext & Ctx,EvalInfo & Info)14666 static bool EvaluateAsRValue(const Expr *E, Expr::EvalResult &Result,
14667 const ASTContext &Ctx, EvalInfo &Info) {
14668 assert(!E->isValueDependent());
14669 bool IsConst;
14670 if (FastEvaluateAsRValue(E, Result, Ctx, IsConst))
14671 return IsConst;
14672
14673 return EvaluateAsRValue(Info, E, Result.Val);
14674 }
14675
EvaluateAsInt(const Expr * E,Expr::EvalResult & ExprResult,const ASTContext & Ctx,Expr::SideEffectsKind AllowSideEffects,EvalInfo & Info)14676 static bool EvaluateAsInt(const Expr *E, Expr::EvalResult &ExprResult,
14677 const ASTContext &Ctx,
14678 Expr::SideEffectsKind AllowSideEffects,
14679 EvalInfo &Info) {
14680 assert(!E->isValueDependent());
14681 if (!E->getType()->isIntegralOrEnumerationType())
14682 return false;
14683
14684 if (!::EvaluateAsRValue(E, ExprResult, Ctx, Info) ||
14685 !ExprResult.Val.isInt() ||
14686 hasUnacceptableSideEffect(ExprResult, AllowSideEffects))
14687 return false;
14688
14689 return true;
14690 }
14691
EvaluateAsFixedPoint(const Expr * E,Expr::EvalResult & ExprResult,const ASTContext & Ctx,Expr::SideEffectsKind AllowSideEffects,EvalInfo & Info)14692 static bool EvaluateAsFixedPoint(const Expr *E, Expr::EvalResult &ExprResult,
14693 const ASTContext &Ctx,
14694 Expr::SideEffectsKind AllowSideEffects,
14695 EvalInfo &Info) {
14696 assert(!E->isValueDependent());
14697 if (!E->getType()->isFixedPointType())
14698 return false;
14699
14700 if (!::EvaluateAsRValue(E, ExprResult, Ctx, Info))
14701 return false;
14702
14703 if (!ExprResult.Val.isFixedPoint() ||
14704 hasUnacceptableSideEffect(ExprResult, AllowSideEffects))
14705 return false;
14706
14707 return true;
14708 }
14709
14710 /// EvaluateAsRValue - Return true if this is a constant which we can fold using
14711 /// any crazy technique (that has nothing to do with language standards) that
14712 /// we want to. If this function returns true, it returns the folded constant
14713 /// in Result. If this expression is a glvalue, an lvalue-to-rvalue conversion
14714 /// will be applied to the result.
EvaluateAsRValue(EvalResult & Result,const ASTContext & Ctx,bool InConstantContext) const14715 bool Expr::EvaluateAsRValue(EvalResult &Result, const ASTContext &Ctx,
14716 bool InConstantContext) const {
14717 assert(!isValueDependent() &&
14718 "Expression evaluator can't be called on a dependent expression.");
14719 EvalInfo Info(Ctx, Result, EvalInfo::EM_IgnoreSideEffects);
14720 Info.InConstantContext = InConstantContext;
14721 return ::EvaluateAsRValue(this, Result, Ctx, Info);
14722 }
14723
EvaluateAsBooleanCondition(bool & Result,const ASTContext & Ctx,bool InConstantContext) const14724 bool Expr::EvaluateAsBooleanCondition(bool &Result, const ASTContext &Ctx,
14725 bool InConstantContext) const {
14726 assert(!isValueDependent() &&
14727 "Expression evaluator can't be called on a dependent expression.");
14728 EvalResult Scratch;
14729 return EvaluateAsRValue(Scratch, Ctx, InConstantContext) &&
14730 HandleConversionToBool(Scratch.Val, Result);
14731 }
14732
EvaluateAsInt(EvalResult & Result,const ASTContext & Ctx,SideEffectsKind AllowSideEffects,bool InConstantContext) const14733 bool Expr::EvaluateAsInt(EvalResult &Result, const ASTContext &Ctx,
14734 SideEffectsKind AllowSideEffects,
14735 bool InConstantContext) const {
14736 assert(!isValueDependent() &&
14737 "Expression evaluator can't be called on a dependent expression.");
14738 EvalInfo Info(Ctx, Result, EvalInfo::EM_IgnoreSideEffects);
14739 Info.InConstantContext = InConstantContext;
14740 return ::EvaluateAsInt(this, Result, Ctx, AllowSideEffects, Info);
14741 }
14742
EvaluateAsFixedPoint(EvalResult & Result,const ASTContext & Ctx,SideEffectsKind AllowSideEffects,bool InConstantContext) const14743 bool Expr::EvaluateAsFixedPoint(EvalResult &Result, const ASTContext &Ctx,
14744 SideEffectsKind AllowSideEffects,
14745 bool InConstantContext) const {
14746 assert(!isValueDependent() &&
14747 "Expression evaluator can't be called on a dependent expression.");
14748 EvalInfo Info(Ctx, Result, EvalInfo::EM_IgnoreSideEffects);
14749 Info.InConstantContext = InConstantContext;
14750 return ::EvaluateAsFixedPoint(this, Result, Ctx, AllowSideEffects, Info);
14751 }
14752
EvaluateAsFloat(APFloat & Result,const ASTContext & Ctx,SideEffectsKind AllowSideEffects,bool InConstantContext) const14753 bool Expr::EvaluateAsFloat(APFloat &Result, const ASTContext &Ctx,
14754 SideEffectsKind AllowSideEffects,
14755 bool InConstantContext) const {
14756 assert(!isValueDependent() &&
14757 "Expression evaluator can't be called on a dependent expression.");
14758
14759 if (!getType()->isRealFloatingType())
14760 return false;
14761
14762 EvalResult ExprResult;
14763 if (!EvaluateAsRValue(ExprResult, Ctx, InConstantContext) ||
14764 !ExprResult.Val.isFloat() ||
14765 hasUnacceptableSideEffect(ExprResult, AllowSideEffects))
14766 return false;
14767
14768 Result = ExprResult.Val.getFloat();
14769 return true;
14770 }
14771
EvaluateAsLValue(EvalResult & Result,const ASTContext & Ctx,bool InConstantContext) const14772 bool Expr::EvaluateAsLValue(EvalResult &Result, const ASTContext &Ctx,
14773 bool InConstantContext) const {
14774 assert(!isValueDependent() &&
14775 "Expression evaluator can't be called on a dependent expression.");
14776
14777 EvalInfo Info(Ctx, Result, EvalInfo::EM_ConstantFold);
14778 Info.InConstantContext = InConstantContext;
14779 LValue LV;
14780 CheckedTemporaries CheckedTemps;
14781 if (!EvaluateLValue(this, LV, Info) || !Info.discardCleanups() ||
14782 Result.HasSideEffects ||
14783 !CheckLValueConstantExpression(Info, getExprLoc(),
14784 Ctx.getLValueReferenceType(getType()), LV,
14785 ConstantExprKind::Normal, CheckedTemps))
14786 return false;
14787
14788 LV.moveInto(Result.Val);
14789 return true;
14790 }
14791
EvaluateDestruction(const ASTContext & Ctx,APValue::LValueBase Base,APValue DestroyedValue,QualType Type,SourceLocation Loc,Expr::EvalStatus & EStatus,bool IsConstantDestruction)14792 static bool EvaluateDestruction(const ASTContext &Ctx, APValue::LValueBase Base,
14793 APValue DestroyedValue, QualType Type,
14794 SourceLocation Loc, Expr::EvalStatus &EStatus,
14795 bool IsConstantDestruction) {
14796 EvalInfo Info(Ctx, EStatus,
14797 IsConstantDestruction ? EvalInfo::EM_ConstantExpression
14798 : EvalInfo::EM_ConstantFold);
14799 Info.setEvaluatingDecl(Base, DestroyedValue,
14800 EvalInfo::EvaluatingDeclKind::Dtor);
14801 Info.InConstantContext = IsConstantDestruction;
14802
14803 LValue LVal;
14804 LVal.set(Base);
14805
14806 if (!HandleDestruction(Info, Loc, Base, DestroyedValue, Type) ||
14807 EStatus.HasSideEffects)
14808 return false;
14809
14810 if (!Info.discardCleanups())
14811 llvm_unreachable("Unhandled cleanup; missing full expression marker?");
14812
14813 return true;
14814 }
14815
EvaluateAsConstantExpr(EvalResult & Result,const ASTContext & Ctx,ConstantExprKind Kind) const14816 bool Expr::EvaluateAsConstantExpr(EvalResult &Result, const ASTContext &Ctx,
14817 ConstantExprKind Kind) const {
14818 assert(!isValueDependent() &&
14819 "Expression evaluator can't be called on a dependent expression.");
14820
14821 EvalInfo::EvaluationMode EM = EvalInfo::EM_ConstantExpression;
14822 EvalInfo Info(Ctx, Result, EM);
14823 Info.InConstantContext = true;
14824
14825 // The type of the object we're initializing is 'const T' for a class NTTP.
14826 QualType T = getType();
14827 if (Kind == ConstantExprKind::ClassTemplateArgument)
14828 T.addConst();
14829
14830 // If we're evaluating a prvalue, fake up a MaterializeTemporaryExpr to
14831 // represent the result of the evaluation. CheckConstantExpression ensures
14832 // this doesn't escape.
14833 MaterializeTemporaryExpr BaseMTE(T, const_cast<Expr*>(this), true);
14834 APValue::LValueBase Base(&BaseMTE);
14835
14836 Info.setEvaluatingDecl(Base, Result.Val);
14837 LValue LVal;
14838 LVal.set(Base);
14839
14840 if (!::EvaluateInPlace(Result.Val, Info, LVal, this) || Result.HasSideEffects)
14841 return false;
14842
14843 if (!Info.discardCleanups())
14844 llvm_unreachable("Unhandled cleanup; missing full expression marker?");
14845
14846 if (!CheckConstantExpression(Info, getExprLoc(), getStorageType(Ctx, this),
14847 Result.Val, Kind))
14848 return false;
14849 if (!CheckMemoryLeaks(Info))
14850 return false;
14851
14852 // If this is a class template argument, it's required to have constant
14853 // destruction too.
14854 if (Kind == ConstantExprKind::ClassTemplateArgument &&
14855 (!EvaluateDestruction(Ctx, Base, Result.Val, T, getBeginLoc(), Result,
14856 true) ||
14857 Result.HasSideEffects)) {
14858 // FIXME: Prefix a note to indicate that the problem is lack of constant
14859 // destruction.
14860 return false;
14861 }
14862
14863 return true;
14864 }
14865
EvaluateAsInitializer(APValue & Value,const ASTContext & Ctx,const VarDecl * VD,SmallVectorImpl<PartialDiagnosticAt> & Notes,bool IsConstantInitialization) const14866 bool Expr::EvaluateAsInitializer(APValue &Value, const ASTContext &Ctx,
14867 const VarDecl *VD,
14868 SmallVectorImpl<PartialDiagnosticAt> &Notes,
14869 bool IsConstantInitialization) const {
14870 assert(!isValueDependent() &&
14871 "Expression evaluator can't be called on a dependent expression.");
14872
14873 // FIXME: Evaluating initializers for large array and record types can cause
14874 // performance problems. Only do so in C++11 for now.
14875 if (isRValue() && (getType()->isArrayType() || getType()->isRecordType()) &&
14876 !Ctx.getLangOpts().CPlusPlus11)
14877 return false;
14878
14879 Expr::EvalStatus EStatus;
14880 EStatus.Diag = &Notes;
14881
14882 EvalInfo Info(Ctx, EStatus,
14883 (IsConstantInitialization && Ctx.getLangOpts().CPlusPlus11)
14884 ? EvalInfo::EM_ConstantExpression
14885 : EvalInfo::EM_ConstantFold);
14886 Info.setEvaluatingDecl(VD, Value);
14887 Info.InConstantContext = IsConstantInitialization;
14888
14889 SourceLocation DeclLoc = VD->getLocation();
14890 QualType DeclTy = VD->getType();
14891
14892 if (Info.EnableNewConstInterp) {
14893 auto &InterpCtx = const_cast<ASTContext &>(Ctx).getInterpContext();
14894 if (!InterpCtx.evaluateAsInitializer(Info, VD, Value))
14895 return false;
14896 } else {
14897 LValue LVal;
14898 LVal.set(VD);
14899
14900 if (!EvaluateInPlace(Value, Info, LVal, this,
14901 /*AllowNonLiteralTypes=*/true) ||
14902 EStatus.HasSideEffects)
14903 return false;
14904
14905 // At this point, any lifetime-extended temporaries are completely
14906 // initialized.
14907 Info.performLifetimeExtension();
14908
14909 if (!Info.discardCleanups())
14910 llvm_unreachable("Unhandled cleanup; missing full expression marker?");
14911 }
14912 return CheckConstantExpression(Info, DeclLoc, DeclTy, Value,
14913 ConstantExprKind::Normal) &&
14914 CheckMemoryLeaks(Info);
14915 }
14916
evaluateDestruction(SmallVectorImpl<PartialDiagnosticAt> & Notes) const14917 bool VarDecl::evaluateDestruction(
14918 SmallVectorImpl<PartialDiagnosticAt> &Notes) const {
14919 Expr::EvalStatus EStatus;
14920 EStatus.Diag = &Notes;
14921
14922 // Only treat the destruction as constant destruction if we formally have
14923 // constant initialization (or are usable in a constant expression).
14924 bool IsConstantDestruction = hasConstantInitialization();
14925
14926 // Make a copy of the value for the destructor to mutate, if we know it.
14927 // Otherwise, treat the value as default-initialized; if the destructor works
14928 // anyway, then the destruction is constant (and must be essentially empty).
14929 APValue DestroyedValue;
14930 if (getEvaluatedValue() && !getEvaluatedValue()->isAbsent())
14931 DestroyedValue = *getEvaluatedValue();
14932 else if (!getDefaultInitValue(getType(), DestroyedValue))
14933 return false;
14934
14935 if (!EvaluateDestruction(getASTContext(), this, std::move(DestroyedValue),
14936 getType(), getLocation(), EStatus,
14937 IsConstantDestruction) ||
14938 EStatus.HasSideEffects)
14939 return false;
14940
14941 ensureEvaluatedStmt()->HasConstantDestruction = true;
14942 return true;
14943 }
14944
14945 /// isEvaluatable - Call EvaluateAsRValue to see if this expression can be
14946 /// constant folded, but discard the result.
isEvaluatable(const ASTContext & Ctx,SideEffectsKind SEK) const14947 bool Expr::isEvaluatable(const ASTContext &Ctx, SideEffectsKind SEK) const {
14948 assert(!isValueDependent() &&
14949 "Expression evaluator can't be called on a dependent expression.");
14950
14951 EvalResult Result;
14952 return EvaluateAsRValue(Result, Ctx, /* in constant context */ true) &&
14953 !hasUnacceptableSideEffect(Result, SEK);
14954 }
14955
EvaluateKnownConstInt(const ASTContext & Ctx,SmallVectorImpl<PartialDiagnosticAt> * Diag) const14956 APSInt Expr::EvaluateKnownConstInt(const ASTContext &Ctx,
14957 SmallVectorImpl<PartialDiagnosticAt> *Diag) const {
14958 assert(!isValueDependent() &&
14959 "Expression evaluator can't be called on a dependent expression.");
14960
14961 EvalResult EVResult;
14962 EVResult.Diag = Diag;
14963 EvalInfo Info(Ctx, EVResult, EvalInfo::EM_IgnoreSideEffects);
14964 Info.InConstantContext = true;
14965
14966 bool Result = ::EvaluateAsRValue(this, EVResult, Ctx, Info);
14967 (void)Result;
14968 assert(Result && "Could not evaluate expression");
14969 assert(EVResult.Val.isInt() && "Expression did not evaluate to integer");
14970
14971 return EVResult.Val.getInt();
14972 }
14973
EvaluateKnownConstIntCheckOverflow(const ASTContext & Ctx,SmallVectorImpl<PartialDiagnosticAt> * Diag) const14974 APSInt Expr::EvaluateKnownConstIntCheckOverflow(
14975 const ASTContext &Ctx, SmallVectorImpl<PartialDiagnosticAt> *Diag) const {
14976 assert(!isValueDependent() &&
14977 "Expression evaluator can't be called on a dependent expression.");
14978
14979 EvalResult EVResult;
14980 EVResult.Diag = Diag;
14981 EvalInfo Info(Ctx, EVResult, EvalInfo::EM_IgnoreSideEffects);
14982 Info.InConstantContext = true;
14983 Info.CheckingForUndefinedBehavior = true;
14984
14985 bool Result = ::EvaluateAsRValue(Info, this, EVResult.Val);
14986 (void)Result;
14987 assert(Result && "Could not evaluate expression");
14988 assert(EVResult.Val.isInt() && "Expression did not evaluate to integer");
14989
14990 return EVResult.Val.getInt();
14991 }
14992
EvaluateForOverflow(const ASTContext & Ctx) const14993 void Expr::EvaluateForOverflow(const ASTContext &Ctx) const {
14994 assert(!isValueDependent() &&
14995 "Expression evaluator can't be called on a dependent expression.");
14996
14997 bool IsConst;
14998 EvalResult EVResult;
14999 if (!FastEvaluateAsRValue(this, EVResult, Ctx, IsConst)) {
15000 EvalInfo Info(Ctx, EVResult, EvalInfo::EM_IgnoreSideEffects);
15001 Info.CheckingForUndefinedBehavior = true;
15002 (void)::EvaluateAsRValue(Info, this, EVResult.Val);
15003 }
15004 }
15005
isGlobalLValue() const15006 bool Expr::EvalResult::isGlobalLValue() const {
15007 assert(Val.isLValue());
15008 return IsGlobalLValue(Val.getLValueBase());
15009 }
15010
15011 /// isIntegerConstantExpr - this recursive routine will test if an expression is
15012 /// an integer constant expression.
15013
15014 /// FIXME: Pass up a reason why! Invalid operation in i-c-e, division by zero,
15015 /// comma, etc
15016
15017 // CheckICE - This function does the fundamental ICE checking: the returned
15018 // ICEDiag contains an ICEKind indicating whether the expression is an ICE,
15019 // and a (possibly null) SourceLocation indicating the location of the problem.
15020 //
15021 // Note that to reduce code duplication, this helper does no evaluation
15022 // itself; the caller checks whether the expression is evaluatable, and
15023 // in the rare cases where CheckICE actually cares about the evaluated
15024 // value, it calls into Evaluate.
15025
15026 namespace {
15027
15028 enum ICEKind {
15029 /// This expression is an ICE.
15030 IK_ICE,
15031 /// This expression is not an ICE, but if it isn't evaluated, it's
15032 /// a legal subexpression for an ICE. This return value is used to handle
15033 /// the comma operator in C99 mode, and non-constant subexpressions.
15034 IK_ICEIfUnevaluated,
15035 /// This expression is not an ICE, and is not a legal subexpression for one.
15036 IK_NotICE
15037 };
15038
15039 struct ICEDiag {
15040 ICEKind Kind;
15041 SourceLocation Loc;
15042
ICEDiag__anon6b379bbb3511::ICEDiag15043 ICEDiag(ICEKind IK, SourceLocation l) : Kind(IK), Loc(l) {}
15044 };
15045
15046 }
15047
NoDiag()15048 static ICEDiag NoDiag() { return ICEDiag(IK_ICE, SourceLocation()); }
15049
Worst(ICEDiag A,ICEDiag B)15050 static ICEDiag Worst(ICEDiag A, ICEDiag B) { return A.Kind >= B.Kind ? A : B; }
15051
CheckEvalInICE(const Expr * E,const ASTContext & Ctx)15052 static ICEDiag CheckEvalInICE(const Expr* E, const ASTContext &Ctx) {
15053 Expr::EvalResult EVResult;
15054 Expr::EvalStatus Status;
15055 EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantExpression);
15056
15057 Info.InConstantContext = true;
15058 if (!::EvaluateAsRValue(E, EVResult, Ctx, Info) || EVResult.HasSideEffects ||
15059 !EVResult.Val.isInt())
15060 return ICEDiag(IK_NotICE, E->getBeginLoc());
15061
15062 return NoDiag();
15063 }
15064
CheckICE(const Expr * E,const ASTContext & Ctx)15065 static ICEDiag CheckICE(const Expr* E, const ASTContext &Ctx) {
15066 assert(!E->isValueDependent() && "Should not see value dependent exprs!");
15067 if (!E->getType()->isIntegralOrEnumerationType())
15068 return ICEDiag(IK_NotICE, E->getBeginLoc());
15069
15070 switch (E->getStmtClass()) {
15071 #define ABSTRACT_STMT(Node)
15072 #define STMT(Node, Base) case Expr::Node##Class:
15073 #define EXPR(Node, Base)
15074 #include "clang/AST/StmtNodes.inc"
15075 case Expr::PredefinedExprClass:
15076 case Expr::FloatingLiteralClass:
15077 case Expr::ImaginaryLiteralClass:
15078 case Expr::StringLiteralClass:
15079 case Expr::ArraySubscriptExprClass:
15080 case Expr::MatrixSubscriptExprClass:
15081 case Expr::OMPArraySectionExprClass:
15082 case Expr::OMPArrayShapingExprClass:
15083 case Expr::OMPIteratorExprClass:
15084 case Expr::MemberExprClass:
15085 case Expr::CompoundAssignOperatorClass:
15086 case Expr::CompoundLiteralExprClass:
15087 case Expr::ExtVectorElementExprClass:
15088 case Expr::DesignatedInitExprClass:
15089 case Expr::ArrayInitLoopExprClass:
15090 case Expr::ArrayInitIndexExprClass:
15091 case Expr::NoInitExprClass:
15092 case Expr::DesignatedInitUpdateExprClass:
15093 case Expr::ImplicitValueInitExprClass:
15094 case Expr::ParenListExprClass:
15095 case Expr::VAArgExprClass:
15096 case Expr::AddrLabelExprClass:
15097 case Expr::StmtExprClass:
15098 case Expr::CXXMemberCallExprClass:
15099 case Expr::CUDAKernelCallExprClass:
15100 case Expr::CXXAddrspaceCastExprClass:
15101 case Expr::CXXDynamicCastExprClass:
15102 case Expr::CXXTypeidExprClass:
15103 case Expr::CXXUuidofExprClass:
15104 case Expr::MSPropertyRefExprClass:
15105 case Expr::MSPropertySubscriptExprClass:
15106 case Expr::CXXNullPtrLiteralExprClass:
15107 case Expr::UserDefinedLiteralClass:
15108 case Expr::CXXThisExprClass:
15109 case Expr::CXXThrowExprClass:
15110 case Expr::CXXNewExprClass:
15111 case Expr::CXXDeleteExprClass:
15112 case Expr::CXXPseudoDestructorExprClass:
15113 case Expr::UnresolvedLookupExprClass:
15114 case Expr::TypoExprClass:
15115 case Expr::RecoveryExprClass:
15116 case Expr::DependentScopeDeclRefExprClass:
15117 case Expr::CXXConstructExprClass:
15118 case Expr::CXXInheritedCtorInitExprClass:
15119 case Expr::CXXStdInitializerListExprClass:
15120 case Expr::CXXBindTemporaryExprClass:
15121 case Expr::ExprWithCleanupsClass:
15122 case Expr::CXXTemporaryObjectExprClass:
15123 case Expr::CXXUnresolvedConstructExprClass:
15124 case Expr::CXXDependentScopeMemberExprClass:
15125 case Expr::UnresolvedMemberExprClass:
15126 case Expr::ObjCStringLiteralClass:
15127 case Expr::ObjCBoxedExprClass:
15128 case Expr::ObjCArrayLiteralClass:
15129 case Expr::ObjCDictionaryLiteralClass:
15130 case Expr::ObjCEncodeExprClass:
15131 case Expr::ObjCMessageExprClass:
15132 case Expr::ObjCSelectorExprClass:
15133 case Expr::ObjCProtocolExprClass:
15134 case Expr::ObjCIvarRefExprClass:
15135 case Expr::ObjCPropertyRefExprClass:
15136 case Expr::ObjCSubscriptRefExprClass:
15137 case Expr::ObjCIsaExprClass:
15138 case Expr::ObjCAvailabilityCheckExprClass:
15139 case Expr::ShuffleVectorExprClass:
15140 case Expr::ConvertVectorExprClass:
15141 case Expr::BlockExprClass:
15142 case Expr::NoStmtClass:
15143 case Expr::OpaqueValueExprClass:
15144 case Expr::PackExpansionExprClass:
15145 case Expr::SubstNonTypeTemplateParmPackExprClass:
15146 case Expr::FunctionParmPackExprClass:
15147 case Expr::AsTypeExprClass:
15148 case Expr::ObjCIndirectCopyRestoreExprClass:
15149 case Expr::MaterializeTemporaryExprClass:
15150 case Expr::PseudoObjectExprClass:
15151 case Expr::AtomicExprClass:
15152 case Expr::LambdaExprClass:
15153 case Expr::CXXFoldExprClass:
15154 case Expr::CoawaitExprClass:
15155 case Expr::DependentCoawaitExprClass:
15156 case Expr::CoyieldExprClass:
15157 return ICEDiag(IK_NotICE, E->getBeginLoc());
15158
15159 case Expr::InitListExprClass: {
15160 // C++03 [dcl.init]p13: If T is a scalar type, then a declaration of the
15161 // form "T x = { a };" is equivalent to "T x = a;".
15162 // Unless we're initializing a reference, T is a scalar as it is known to be
15163 // of integral or enumeration type.
15164 if (E->isRValue())
15165 if (cast<InitListExpr>(E)->getNumInits() == 1)
15166 return CheckICE(cast<InitListExpr>(E)->getInit(0), Ctx);
15167 return ICEDiag(IK_NotICE, E->getBeginLoc());
15168 }
15169
15170 case Expr::SizeOfPackExprClass:
15171 case Expr::GNUNullExprClass:
15172 case Expr::SourceLocExprClass:
15173 return NoDiag();
15174
15175 case Expr::SubstNonTypeTemplateParmExprClass:
15176 return
15177 CheckICE(cast<SubstNonTypeTemplateParmExpr>(E)->getReplacement(), Ctx);
15178
15179 case Expr::ConstantExprClass:
15180 return CheckICE(cast<ConstantExpr>(E)->getSubExpr(), Ctx);
15181
15182 case Expr::ParenExprClass:
15183 return CheckICE(cast<ParenExpr>(E)->getSubExpr(), Ctx);
15184 case Expr::GenericSelectionExprClass:
15185 return CheckICE(cast<GenericSelectionExpr>(E)->getResultExpr(), Ctx);
15186 case Expr::IntegerLiteralClass:
15187 case Expr::FixedPointLiteralClass:
15188 case Expr::CharacterLiteralClass:
15189 case Expr::ObjCBoolLiteralExprClass:
15190 case Expr::CXXBoolLiteralExprClass:
15191 case Expr::CXXScalarValueInitExprClass:
15192 case Expr::TypeTraitExprClass:
15193 case Expr::ConceptSpecializationExprClass:
15194 case Expr::RequiresExprClass:
15195 case Expr::ArrayTypeTraitExprClass:
15196 case Expr::ExpressionTraitExprClass:
15197 case Expr::CXXNoexceptExprClass:
15198 return NoDiag();
15199 case Expr::CallExprClass:
15200 case Expr::CXXOperatorCallExprClass: {
15201 // C99 6.6/3 allows function calls within unevaluated subexpressions of
15202 // constant expressions, but they can never be ICEs because an ICE cannot
15203 // contain an operand of (pointer to) function type.
15204 const CallExpr *CE = cast<CallExpr>(E);
15205 if (CE->getBuiltinCallee())
15206 return CheckEvalInICE(E, Ctx);
15207 return ICEDiag(IK_NotICE, E->getBeginLoc());
15208 }
15209 case Expr::CXXRewrittenBinaryOperatorClass:
15210 return CheckICE(cast<CXXRewrittenBinaryOperator>(E)->getSemanticForm(),
15211 Ctx);
15212 case Expr::DeclRefExprClass: {
15213 const NamedDecl *D = cast<DeclRefExpr>(E)->getDecl();
15214 if (isa<EnumConstantDecl>(D))
15215 return NoDiag();
15216
15217 // C++ and OpenCL (FIXME: spec reference?) allow reading const-qualified
15218 // integer variables in constant expressions:
15219 //
15220 // C++ 7.1.5.1p2
15221 // A variable of non-volatile const-qualified integral or enumeration
15222 // type initialized by an ICE can be used in ICEs.
15223 //
15224 // We sometimes use CheckICE to check the C++98 rules in C++11 mode. In
15225 // that mode, use of reference variables should not be allowed.
15226 const VarDecl *VD = dyn_cast<VarDecl>(D);
15227 if (VD && VD->isUsableInConstantExpressions(Ctx) &&
15228 !VD->getType()->isReferenceType())
15229 return NoDiag();
15230
15231 return ICEDiag(IK_NotICE, E->getBeginLoc());
15232 }
15233 case Expr::UnaryOperatorClass: {
15234 const UnaryOperator *Exp = cast<UnaryOperator>(E);
15235 switch (Exp->getOpcode()) {
15236 case UO_PostInc:
15237 case UO_PostDec:
15238 case UO_PreInc:
15239 case UO_PreDec:
15240 case UO_AddrOf:
15241 case UO_Deref:
15242 case UO_Coawait:
15243 // C99 6.6/3 allows increment and decrement within unevaluated
15244 // subexpressions of constant expressions, but they can never be ICEs
15245 // because an ICE cannot contain an lvalue operand.
15246 return ICEDiag(IK_NotICE, E->getBeginLoc());
15247 case UO_Extension:
15248 case UO_LNot:
15249 case UO_Plus:
15250 case UO_Minus:
15251 case UO_Not:
15252 case UO_Real:
15253 case UO_Imag:
15254 return CheckICE(Exp->getSubExpr(), Ctx);
15255 }
15256 llvm_unreachable("invalid unary operator class");
15257 }
15258 case Expr::OffsetOfExprClass: {
15259 // Note that per C99, offsetof must be an ICE. And AFAIK, using
15260 // EvaluateAsRValue matches the proposed gcc behavior for cases like
15261 // "offsetof(struct s{int x[4];}, x[1.0])". This doesn't affect
15262 // compliance: we should warn earlier for offsetof expressions with
15263 // array subscripts that aren't ICEs, and if the array subscripts
15264 // are ICEs, the value of the offsetof must be an integer constant.
15265 return CheckEvalInICE(E, Ctx);
15266 }
15267 case Expr::UnaryExprOrTypeTraitExprClass: {
15268 const UnaryExprOrTypeTraitExpr *Exp = cast<UnaryExprOrTypeTraitExpr>(E);
15269 if ((Exp->getKind() == UETT_SizeOf) &&
15270 Exp->getTypeOfArgument()->isVariableArrayType())
15271 return ICEDiag(IK_NotICE, E->getBeginLoc());
15272 return NoDiag();
15273 }
15274 case Expr::BinaryOperatorClass: {
15275 const BinaryOperator *Exp = cast<BinaryOperator>(E);
15276 switch (Exp->getOpcode()) {
15277 case BO_PtrMemD:
15278 case BO_PtrMemI:
15279 case BO_Assign:
15280 case BO_MulAssign:
15281 case BO_DivAssign:
15282 case BO_RemAssign:
15283 case BO_AddAssign:
15284 case BO_SubAssign:
15285 case BO_ShlAssign:
15286 case BO_ShrAssign:
15287 case BO_AndAssign:
15288 case BO_XorAssign:
15289 case BO_OrAssign:
15290 // C99 6.6/3 allows assignments within unevaluated subexpressions of
15291 // constant expressions, but they can never be ICEs because an ICE cannot
15292 // contain an lvalue operand.
15293 return ICEDiag(IK_NotICE, E->getBeginLoc());
15294
15295 case BO_Mul:
15296 case BO_Div:
15297 case BO_Rem:
15298 case BO_Add:
15299 case BO_Sub:
15300 case BO_Shl:
15301 case BO_Shr:
15302 case BO_LT:
15303 case BO_GT:
15304 case BO_LE:
15305 case BO_GE:
15306 case BO_EQ:
15307 case BO_NE:
15308 case BO_And:
15309 case BO_Xor:
15310 case BO_Or:
15311 case BO_Comma:
15312 case BO_Cmp: {
15313 ICEDiag LHSResult = CheckICE(Exp->getLHS(), Ctx);
15314 ICEDiag RHSResult = CheckICE(Exp->getRHS(), Ctx);
15315 if (Exp->getOpcode() == BO_Div ||
15316 Exp->getOpcode() == BO_Rem) {
15317 // EvaluateAsRValue gives an error for undefined Div/Rem, so make sure
15318 // we don't evaluate one.
15319 if (LHSResult.Kind == IK_ICE && RHSResult.Kind == IK_ICE) {
15320 llvm::APSInt REval = Exp->getRHS()->EvaluateKnownConstInt(Ctx);
15321 if (REval == 0)
15322 return ICEDiag(IK_ICEIfUnevaluated, E->getBeginLoc());
15323 if (REval.isSigned() && REval.isAllOnesValue()) {
15324 llvm::APSInt LEval = Exp->getLHS()->EvaluateKnownConstInt(Ctx);
15325 if (LEval.isMinSignedValue())
15326 return ICEDiag(IK_ICEIfUnevaluated, E->getBeginLoc());
15327 }
15328 }
15329 }
15330 if (Exp->getOpcode() == BO_Comma) {
15331 if (Ctx.getLangOpts().C99) {
15332 // C99 6.6p3 introduces a strange edge case: comma can be in an ICE
15333 // if it isn't evaluated.
15334 if (LHSResult.Kind == IK_ICE && RHSResult.Kind == IK_ICE)
15335 return ICEDiag(IK_ICEIfUnevaluated, E->getBeginLoc());
15336 } else {
15337 // In both C89 and C++, commas in ICEs are illegal.
15338 return ICEDiag(IK_NotICE, E->getBeginLoc());
15339 }
15340 }
15341 return Worst(LHSResult, RHSResult);
15342 }
15343 case BO_LAnd:
15344 case BO_LOr: {
15345 ICEDiag LHSResult = CheckICE(Exp->getLHS(), Ctx);
15346 ICEDiag RHSResult = CheckICE(Exp->getRHS(), Ctx);
15347 if (LHSResult.Kind == IK_ICE && RHSResult.Kind == IK_ICEIfUnevaluated) {
15348 // Rare case where the RHS has a comma "side-effect"; we need
15349 // to actually check the condition to see whether the side
15350 // with the comma is evaluated.
15351 if ((Exp->getOpcode() == BO_LAnd) !=
15352 (Exp->getLHS()->EvaluateKnownConstInt(Ctx) == 0))
15353 return RHSResult;
15354 return NoDiag();
15355 }
15356
15357 return Worst(LHSResult, RHSResult);
15358 }
15359 }
15360 llvm_unreachable("invalid binary operator kind");
15361 }
15362 case Expr::ImplicitCastExprClass:
15363 case Expr::CStyleCastExprClass:
15364 case Expr::CXXFunctionalCastExprClass:
15365 case Expr::CXXStaticCastExprClass:
15366 case Expr::CXXReinterpretCastExprClass:
15367 case Expr::CXXConstCastExprClass:
15368 case Expr::ObjCBridgedCastExprClass: {
15369 const Expr *SubExpr = cast<CastExpr>(E)->getSubExpr();
15370 if (isa<ExplicitCastExpr>(E)) {
15371 if (const FloatingLiteral *FL
15372 = dyn_cast<FloatingLiteral>(SubExpr->IgnoreParenImpCasts())) {
15373 unsigned DestWidth = Ctx.getIntWidth(E->getType());
15374 bool DestSigned = E->getType()->isSignedIntegerOrEnumerationType();
15375 APSInt IgnoredVal(DestWidth, !DestSigned);
15376 bool Ignored;
15377 // If the value does not fit in the destination type, the behavior is
15378 // undefined, so we are not required to treat it as a constant
15379 // expression.
15380 if (FL->getValue().convertToInteger(IgnoredVal,
15381 llvm::APFloat::rmTowardZero,
15382 &Ignored) & APFloat::opInvalidOp)
15383 return ICEDiag(IK_NotICE, E->getBeginLoc());
15384 return NoDiag();
15385 }
15386 }
15387 switch (cast<CastExpr>(E)->getCastKind()) {
15388 case CK_LValueToRValue:
15389 case CK_AtomicToNonAtomic:
15390 case CK_NonAtomicToAtomic:
15391 case CK_NoOp:
15392 case CK_IntegralToBoolean:
15393 case CK_IntegralCast:
15394 return CheckICE(SubExpr, Ctx);
15395 default:
15396 return ICEDiag(IK_NotICE, E->getBeginLoc());
15397 }
15398 }
15399 case Expr::BinaryConditionalOperatorClass: {
15400 const BinaryConditionalOperator *Exp = cast<BinaryConditionalOperator>(E);
15401 ICEDiag CommonResult = CheckICE(Exp->getCommon(), Ctx);
15402 if (CommonResult.Kind == IK_NotICE) return CommonResult;
15403 ICEDiag FalseResult = CheckICE(Exp->getFalseExpr(), Ctx);
15404 if (FalseResult.Kind == IK_NotICE) return FalseResult;
15405 if (CommonResult.Kind == IK_ICEIfUnevaluated) return CommonResult;
15406 if (FalseResult.Kind == IK_ICEIfUnevaluated &&
15407 Exp->getCommon()->EvaluateKnownConstInt(Ctx) != 0) return NoDiag();
15408 return FalseResult;
15409 }
15410 case Expr::ConditionalOperatorClass: {
15411 const ConditionalOperator *Exp = cast<ConditionalOperator>(E);
15412 // If the condition (ignoring parens) is a __builtin_constant_p call,
15413 // then only the true side is actually considered in an integer constant
15414 // expression, and it is fully evaluated. This is an important GNU
15415 // extension. See GCC PR38377 for discussion.
15416 if (const CallExpr *CallCE
15417 = dyn_cast<CallExpr>(Exp->getCond()->IgnoreParenCasts()))
15418 if (CallCE->getBuiltinCallee() == Builtin::BI__builtin_constant_p)
15419 return CheckEvalInICE(E, Ctx);
15420 ICEDiag CondResult = CheckICE(Exp->getCond(), Ctx);
15421 if (CondResult.Kind == IK_NotICE)
15422 return CondResult;
15423
15424 ICEDiag TrueResult = CheckICE(Exp->getTrueExpr(), Ctx);
15425 ICEDiag FalseResult = CheckICE(Exp->getFalseExpr(), Ctx);
15426
15427 if (TrueResult.Kind == IK_NotICE)
15428 return TrueResult;
15429 if (FalseResult.Kind == IK_NotICE)
15430 return FalseResult;
15431 if (CondResult.Kind == IK_ICEIfUnevaluated)
15432 return CondResult;
15433 if (TrueResult.Kind == IK_ICE && FalseResult.Kind == IK_ICE)
15434 return NoDiag();
15435 // Rare case where the diagnostics depend on which side is evaluated
15436 // Note that if we get here, CondResult is 0, and at least one of
15437 // TrueResult and FalseResult is non-zero.
15438 if (Exp->getCond()->EvaluateKnownConstInt(Ctx) == 0)
15439 return FalseResult;
15440 return TrueResult;
15441 }
15442 case Expr::CXXDefaultArgExprClass:
15443 return CheckICE(cast<CXXDefaultArgExpr>(E)->getExpr(), Ctx);
15444 case Expr::CXXDefaultInitExprClass:
15445 return CheckICE(cast<CXXDefaultInitExpr>(E)->getExpr(), Ctx);
15446 case Expr::ChooseExprClass: {
15447 return CheckICE(cast<ChooseExpr>(E)->getChosenSubExpr(), Ctx);
15448 }
15449 case Expr::BuiltinBitCastExprClass: {
15450 if (!checkBitCastConstexprEligibility(nullptr, Ctx, cast<CastExpr>(E)))
15451 return ICEDiag(IK_NotICE, E->getBeginLoc());
15452 return CheckICE(cast<CastExpr>(E)->getSubExpr(), Ctx);
15453 }
15454 }
15455
15456 llvm_unreachable("Invalid StmtClass!");
15457 }
15458
15459 /// Evaluate an expression as a C++11 integral constant expression.
EvaluateCPlusPlus11IntegralConstantExpr(const ASTContext & Ctx,const Expr * E,llvm::APSInt * Value,SourceLocation * Loc)15460 static bool EvaluateCPlusPlus11IntegralConstantExpr(const ASTContext &Ctx,
15461 const Expr *E,
15462 llvm::APSInt *Value,
15463 SourceLocation *Loc) {
15464 if (!E->getType()->isIntegralOrUnscopedEnumerationType()) {
15465 if (Loc) *Loc = E->getExprLoc();
15466 return false;
15467 }
15468
15469 APValue Result;
15470 if (!E->isCXX11ConstantExpr(Ctx, &Result, Loc))
15471 return false;
15472
15473 if (!Result.isInt()) {
15474 if (Loc) *Loc = E->getExprLoc();
15475 return false;
15476 }
15477
15478 if (Value) *Value = Result.getInt();
15479 return true;
15480 }
15481
isIntegerConstantExpr(const ASTContext & Ctx,SourceLocation * Loc) const15482 bool Expr::isIntegerConstantExpr(const ASTContext &Ctx,
15483 SourceLocation *Loc) const {
15484 assert(!isValueDependent() &&
15485 "Expression evaluator can't be called on a dependent expression.");
15486
15487 if (Ctx.getLangOpts().CPlusPlus11)
15488 return EvaluateCPlusPlus11IntegralConstantExpr(Ctx, this, nullptr, Loc);
15489
15490 ICEDiag D = CheckICE(this, Ctx);
15491 if (D.Kind != IK_ICE) {
15492 if (Loc) *Loc = D.Loc;
15493 return false;
15494 }
15495 return true;
15496 }
15497
getIntegerConstantExpr(const ASTContext & Ctx,SourceLocation * Loc,bool isEvaluated) const15498 Optional<llvm::APSInt> Expr::getIntegerConstantExpr(const ASTContext &Ctx,
15499 SourceLocation *Loc,
15500 bool isEvaluated) const {
15501 assert(!isValueDependent() &&
15502 "Expression evaluator can't be called on a dependent expression.");
15503
15504 APSInt Value;
15505
15506 if (Ctx.getLangOpts().CPlusPlus11) {
15507 if (EvaluateCPlusPlus11IntegralConstantExpr(Ctx, this, &Value, Loc))
15508 return Value;
15509 return None;
15510 }
15511
15512 if (!isIntegerConstantExpr(Ctx, Loc))
15513 return None;
15514
15515 // The only possible side-effects here are due to UB discovered in the
15516 // evaluation (for instance, INT_MAX + 1). In such a case, we are still
15517 // required to treat the expression as an ICE, so we produce the folded
15518 // value.
15519 EvalResult ExprResult;
15520 Expr::EvalStatus Status;
15521 EvalInfo Info(Ctx, Status, EvalInfo::EM_IgnoreSideEffects);
15522 Info.InConstantContext = true;
15523
15524 if (!::EvaluateAsInt(this, ExprResult, Ctx, SE_AllowSideEffects, Info))
15525 llvm_unreachable("ICE cannot be evaluated!");
15526
15527 return ExprResult.Val.getInt();
15528 }
15529
isCXX98IntegralConstantExpr(const ASTContext & Ctx) const15530 bool Expr::isCXX98IntegralConstantExpr(const ASTContext &Ctx) const {
15531 assert(!isValueDependent() &&
15532 "Expression evaluator can't be called on a dependent expression.");
15533
15534 return CheckICE(this, Ctx).Kind == IK_ICE;
15535 }
15536
isCXX11ConstantExpr(const ASTContext & Ctx,APValue * Result,SourceLocation * Loc) const15537 bool Expr::isCXX11ConstantExpr(const ASTContext &Ctx, APValue *Result,
15538 SourceLocation *Loc) const {
15539 assert(!isValueDependent() &&
15540 "Expression evaluator can't be called on a dependent expression.");
15541
15542 // We support this checking in C++98 mode in order to diagnose compatibility
15543 // issues.
15544 assert(Ctx.getLangOpts().CPlusPlus);
15545
15546 // Build evaluation settings.
15547 Expr::EvalStatus Status;
15548 SmallVector<PartialDiagnosticAt, 8> Diags;
15549 Status.Diag = &Diags;
15550 EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantExpression);
15551
15552 APValue Scratch;
15553 bool IsConstExpr =
15554 ::EvaluateAsRValue(Info, this, Result ? *Result : Scratch) &&
15555 // FIXME: We don't produce a diagnostic for this, but the callers that
15556 // call us on arbitrary full-expressions should generally not care.
15557 Info.discardCleanups() && !Status.HasSideEffects;
15558
15559 if (!Diags.empty()) {
15560 IsConstExpr = false;
15561 if (Loc) *Loc = Diags[0].first;
15562 } else if (!IsConstExpr) {
15563 // FIXME: This shouldn't happen.
15564 if (Loc) *Loc = getExprLoc();
15565 }
15566
15567 return IsConstExpr;
15568 }
15569
EvaluateWithSubstitution(APValue & Value,ASTContext & Ctx,const FunctionDecl * Callee,ArrayRef<const Expr * > Args,const Expr * This) const15570 bool Expr::EvaluateWithSubstitution(APValue &Value, ASTContext &Ctx,
15571 const FunctionDecl *Callee,
15572 ArrayRef<const Expr*> Args,
15573 const Expr *This) const {
15574 assert(!isValueDependent() &&
15575 "Expression evaluator can't be called on a dependent expression.");
15576
15577 Expr::EvalStatus Status;
15578 EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantExpressionUnevaluated);
15579 Info.InConstantContext = true;
15580
15581 LValue ThisVal;
15582 const LValue *ThisPtr = nullptr;
15583 if (This) {
15584 #ifndef NDEBUG
15585 auto *MD = dyn_cast<CXXMethodDecl>(Callee);
15586 assert(MD && "Don't provide `this` for non-methods.");
15587 assert(!MD->isStatic() && "Don't provide `this` for static methods.");
15588 #endif
15589 if (!This->isValueDependent() &&
15590 EvaluateObjectArgument(Info, This, ThisVal) &&
15591 !Info.EvalStatus.HasSideEffects)
15592 ThisPtr = &ThisVal;
15593
15594 // Ignore any side-effects from a failed evaluation. This is safe because
15595 // they can't interfere with any other argument evaluation.
15596 Info.EvalStatus.HasSideEffects = false;
15597 }
15598
15599 CallRef Call = Info.CurrentCall->createCall(Callee);
15600 for (ArrayRef<const Expr*>::iterator I = Args.begin(), E = Args.end();
15601 I != E; ++I) {
15602 unsigned Idx = I - Args.begin();
15603 if (Idx >= Callee->getNumParams())
15604 break;
15605 const ParmVarDecl *PVD = Callee->getParamDecl(Idx);
15606 if ((*I)->isValueDependent() ||
15607 !EvaluateCallArg(PVD, *I, Call, Info) ||
15608 Info.EvalStatus.HasSideEffects) {
15609 // If evaluation fails, throw away the argument entirely.
15610 if (APValue *Slot = Info.getParamSlot(Call, PVD))
15611 *Slot = APValue();
15612 }
15613
15614 // Ignore any side-effects from a failed evaluation. This is safe because
15615 // they can't interfere with any other argument evaluation.
15616 Info.EvalStatus.HasSideEffects = false;
15617 }
15618
15619 // Parameter cleanups happen in the caller and are not part of this
15620 // evaluation.
15621 Info.discardCleanups();
15622 Info.EvalStatus.HasSideEffects = false;
15623
15624 // Build fake call to Callee.
15625 CallStackFrame Frame(Info, Callee->getLocation(), Callee, ThisPtr, Call);
15626 // FIXME: Missing ExprWithCleanups in enable_if conditions?
15627 FullExpressionRAII Scope(Info);
15628 return Evaluate(Value, Info, this) && Scope.destroy() &&
15629 !Info.EvalStatus.HasSideEffects;
15630 }
15631
isPotentialConstantExpr(const FunctionDecl * FD,SmallVectorImpl<PartialDiagnosticAt> & Diags)15632 bool Expr::isPotentialConstantExpr(const FunctionDecl *FD,
15633 SmallVectorImpl<
15634 PartialDiagnosticAt> &Diags) {
15635 // FIXME: It would be useful to check constexpr function templates, but at the
15636 // moment the constant expression evaluator cannot cope with the non-rigorous
15637 // ASTs which we build for dependent expressions.
15638 if (FD->isDependentContext())
15639 return true;
15640
15641 Expr::EvalStatus Status;
15642 Status.Diag = &Diags;
15643
15644 EvalInfo Info(FD->getASTContext(), Status, EvalInfo::EM_ConstantExpression);
15645 Info.InConstantContext = true;
15646 Info.CheckingPotentialConstantExpression = true;
15647
15648 // The constexpr VM attempts to compile all methods to bytecode here.
15649 if (Info.EnableNewConstInterp) {
15650 Info.Ctx.getInterpContext().isPotentialConstantExpr(Info, FD);
15651 return Diags.empty();
15652 }
15653
15654 const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD);
15655 const CXXRecordDecl *RD = MD ? MD->getParent()->getCanonicalDecl() : nullptr;
15656
15657 // Fabricate an arbitrary expression on the stack and pretend that it
15658 // is a temporary being used as the 'this' pointer.
15659 LValue This;
15660 ImplicitValueInitExpr VIE(RD ? Info.Ctx.getRecordType(RD) : Info.Ctx.IntTy);
15661 This.set({&VIE, Info.CurrentCall->Index});
15662
15663 ArrayRef<const Expr*> Args;
15664
15665 APValue Scratch;
15666 if (const CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(FD)) {
15667 // Evaluate the call as a constant initializer, to allow the construction
15668 // of objects of non-literal types.
15669 Info.setEvaluatingDecl(This.getLValueBase(), Scratch);
15670 HandleConstructorCall(&VIE, This, Args, CD, Info, Scratch);
15671 } else {
15672 SourceLocation Loc = FD->getLocation();
15673 HandleFunctionCall(Loc, FD, (MD && MD->isInstance()) ? &This : nullptr,
15674 Args, CallRef(), FD->getBody(), Info, Scratch, nullptr);
15675 }
15676
15677 return Diags.empty();
15678 }
15679
isPotentialConstantExprUnevaluated(Expr * E,const FunctionDecl * FD,SmallVectorImpl<PartialDiagnosticAt> & Diags)15680 bool Expr::isPotentialConstantExprUnevaluated(Expr *E,
15681 const FunctionDecl *FD,
15682 SmallVectorImpl<
15683 PartialDiagnosticAt> &Diags) {
15684 assert(!E->isValueDependent() &&
15685 "Expression evaluator can't be called on a dependent expression.");
15686
15687 Expr::EvalStatus Status;
15688 Status.Diag = &Diags;
15689
15690 EvalInfo Info(FD->getASTContext(), Status,
15691 EvalInfo::EM_ConstantExpressionUnevaluated);
15692 Info.InConstantContext = true;
15693 Info.CheckingPotentialConstantExpression = true;
15694
15695 // Fabricate a call stack frame to give the arguments a plausible cover story.
15696 CallStackFrame Frame(Info, SourceLocation(), FD, /*This*/ nullptr, CallRef());
15697
15698 APValue ResultScratch;
15699 Evaluate(ResultScratch, Info, E);
15700 return Diags.empty();
15701 }
15702
tryEvaluateObjectSize(uint64_t & Result,ASTContext & Ctx,unsigned Type) const15703 bool Expr::tryEvaluateObjectSize(uint64_t &Result, ASTContext &Ctx,
15704 unsigned Type) const {
15705 if (!getType()->isPointerType())
15706 return false;
15707
15708 Expr::EvalStatus Status;
15709 EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantFold);
15710 return tryEvaluateBuiltinObjectSize(this, Type, Info, Result);
15711 }
15712