clang 17.0.0git
ExprConstant.cpp
Go to the documentation of this file.
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"
41#include "clang/AST/ASTLambda.h"
42#include "clang/AST/Attr.h"
44#include "clang/AST/CharUnits.h"
46#include "clang/AST/Expr.h"
47#include "clang/AST/OSLog.h"
51#include "clang/AST/TypeLoc.h"
54#include "llvm/ADT/APFixedPoint.h"
55#include "llvm/ADT/SmallBitVector.h"
56#include "llvm/Support/Debug.h"
57#include "llvm/Support/SaveAndRestore.h"
58#include "llvm/Support/TimeProfiler.h"
59#include "llvm/Support/raw_ostream.h"
60#include <cstring>
61#include <functional>
62#include <optional>
63
64#define DEBUG_TYPE "exprconstant"
65
66using namespace clang;
67using llvm::APFixedPoint;
68using llvm::APInt;
69using llvm::APSInt;
70using llvm::APFloat;
71using llvm::FixedPointSemantics;
72
73namespace {
74 struct LValue;
75 class CallStackFrame;
76 class EvalInfo;
77
78 using SourceLocExprScopeGuard =
80
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.
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.
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.
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.
103 static QualType getStorageType(const ASTContext &Ctx, const Expr *E) {
104 if (E->isPRValue())
105 return E->getType();
106 return Ctx.getLValueReferenceType(E->getType());
107 }
108
109 /// Given a CallExpr, try to get the alloc_size attribute. May return null.
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.
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.
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).
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
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
190 findMostDerivedSubobject(ASTContext &Ctx, APValue::LValueBase Base,
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.
271
272 SubobjectDesignator() : Invalid(true) {}
273
274 explicit SubobjectDesignator(QualType T)
275 : Invalid(false), IsOnePastTheEnd(false),
276 FirstEntryIsAnUnsizedArray(false), MostDerivedIsArrayElement(false),
277 MostDerivedPathLength(0), MostDerivedArraySize(0),
278 MostDerivedType(T) {}
279
280 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
301 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
322 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.
329 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.
336 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.
342 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}
356 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.
373 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.
383 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.
391 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.
402 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.
415 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.
427 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.
441 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 {
495 CallRef() : OrigCallee(), CallIndex(0), Version() {}
496 CallRef(const FunctionDecl *Callee, unsigned CallIndex, unsigned Version)
497 : OrigCallee(Callee), CallIndex(CallIndex), Version(Version) {}
498
499 explicit operator bool() const { return OrigCallee; }
500
501 /// Get the parameter that the caller initialized, corresponding to the
502 /// given parameter in the callee.
503 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
559 unsigned getTempVersion() const { return TempVersionStack.back(); }
560
561 void pushTempVersion() {
562 TempVersionStack.push_back(++CurTempVersion);
563 }
564
565 void popTempVersion() {
566 TempVersionStack.pop_back();
567 }
568
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 ValueDecl *, 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.
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 return nullptr;
596 }
597
598 // Return the current temporary for Key in the map.
599 APValue *getCurrentTemporary(const void *Key) {
600 auto UB = Temporaries.upper_bound(MapKeyTy(Key, UINT_MAX));
601 if (UB != Temporaries.begin() && std::prev(UB)->first.first == Key)
602 return &std::prev(UB)->second;
603 return nullptr;
604 }
605
606 // Return the version number of the current temporary for Key.
607 unsigned getCurrentTemporaryVersion(const void *Key) const {
608 auto UB = Temporaries.upper_bound(MapKeyTy(Key, UINT_MAX));
609 if (UB != Temporaries.begin() && std::prev(UB)->first.first == Key)
610 return std::prev(UB)->first.second;
611 return 0;
612 }
613
614 /// Allocate storage for an object of type T in this stack frame.
615 /// Populates LV with a handle to the created object. Key identifies
616 /// the temporary within the stack frame, and must not be reused without
617 /// bumping the temporary version number.
618 template<typename KeyT>
619 APValue &createTemporary(const KeyT *Key, QualType T,
620 ScopeKind Scope, LValue &LV);
621
622 /// Allocate storage for a parameter of a function call made in this frame.
623 APValue &createParam(CallRef Args, const ParmVarDecl *PVD, LValue &LV);
624
625 void describe(llvm::raw_ostream &OS) override;
626
627 Frame *getCaller() const override { return Caller; }
628 SourceLocation getCallLocation() const override { return CallLoc; }
629 const FunctionDecl *getCallee() const override { return Callee; }
630
631 bool isStdFunction() const {
632 for (const DeclContext *DC = Callee; DC; DC = DC->getParent())
633 if (DC->isStdNamespace())
634 return true;
635 return false;
636 }
637
638 private:
639 APValue &createLocal(APValue::LValueBase Base, const void *Key, QualType T,
640 ScopeKind Scope);
641 };
642
643 /// Temporarily override 'this'.
644 class ThisOverrideRAII {
645 public:
646 ThisOverrideRAII(CallStackFrame &Frame, const LValue *NewThis, bool Enable)
647 : Frame(Frame), OldThis(Frame.This) {
648 if (Enable)
649 Frame.This = NewThis;
650 }
651 ~ThisOverrideRAII() {
652 Frame.This = OldThis;
653 }
654 private:
655 CallStackFrame &Frame;
656 const LValue *OldThis;
657 };
658
659 // A shorthand time trace scope struct, prints source range, for example
660 // {"name":"EvaluateAsRValue","args":{"detail":"<test.cc:8:21, col:25>"}}}
661 class ExprTimeTraceScope {
662 public:
663 ExprTimeTraceScope(const Expr *E, const ASTContext &Ctx, StringRef Name)
664 : TimeScope(Name, [E, &Ctx] {
665 return E->getSourceRange().printToString(Ctx.getSourceManager());
666 }) {}
667
668 private:
669 llvm::TimeTraceScope TimeScope;
670 };
671}
672
673static bool HandleDestruction(EvalInfo &Info, const Expr *E,
674 const LValue &This, QualType ThisType);
675static bool HandleDestruction(EvalInfo &Info, SourceLocation Loc,
677 QualType T);
678
679namespace {
680 /// A cleanup, and a flag indicating whether it is lifetime-extended.
681 class Cleanup {
682 llvm::PointerIntPair<APValue*, 2, ScopeKind> Value;
684 QualType T;
685
686 public:
687 Cleanup(APValue *Val, APValue::LValueBase Base, QualType T,
688 ScopeKind Scope)
689 : Value(Val, Scope), Base(Base), T(T) {}
690
691 /// Determine whether this cleanup should be performed at the end of the
692 /// given kind of scope.
693 bool isDestroyedAtEndOf(ScopeKind K) const {
694 return (int)Value.getInt() >= (int)K;
695 }
696 bool endLifetime(EvalInfo &Info, bool RunDestructors) {
697 if (RunDestructors) {
698 SourceLocation Loc;
699 if (const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>())
700 Loc = VD->getLocation();
701 else if (const Expr *E = Base.dyn_cast<const Expr*>())
702 Loc = E->getExprLoc();
703 return HandleDestruction(Info, Loc, Base, *Value.getPointer(), T);
704 }
705 *Value.getPointer() = APValue();
706 return true;
707 }
708
709 bool hasSideEffect() {
710 return T.isDestructedType();
711 }
712 };
713
714 /// A reference to an object whose construction we are currently evaluating.
715 struct ObjectUnderConstruction {
718 friend bool operator==(const ObjectUnderConstruction &LHS,
719 const ObjectUnderConstruction &RHS) {
720 return LHS.Base == RHS.Base && LHS.Path == RHS.Path;
721 }
722 friend llvm::hash_code hash_value(const ObjectUnderConstruction &Obj) {
723 return llvm::hash_combine(Obj.Base, Obj.Path);
724 }
725 };
726 enum class ConstructionPhase {
727 None,
728 Bases,
729 AfterBases,
730 AfterFields,
731 Destroying,
732 DestroyingBases
733 };
734}
735
736namespace llvm {
737template<> struct DenseMapInfo<ObjectUnderConstruction> {
738 using Base = DenseMapInfo<APValue::LValueBase>;
739 static ObjectUnderConstruction getEmptyKey() {
740 return {Base::getEmptyKey(), {}}; }
741 static ObjectUnderConstruction getTombstoneKey() {
742 return {Base::getTombstoneKey(), {}};
743 }
744 static unsigned getHashValue(const ObjectUnderConstruction &Object) {
745 return hash_value(Object);
746 }
747 static bool isEqual(const ObjectUnderConstruction &LHS,
748 const ObjectUnderConstruction &RHS) {
749 return LHS == RHS;
750 }
751};
752}
753
754namespace {
755 /// A dynamically-allocated heap object.
756 struct DynAlloc {
757 /// The value of this heap-allocated object.
759 /// The allocating expression; used for diagnostics. Either a CXXNewExpr
760 /// or a CallExpr (the latter is for direct calls to operator new inside
761 /// std::allocator<T>::allocate).
762 const Expr *AllocExpr = nullptr;
763
764 enum Kind {
765 New,
766 ArrayNew,
767 StdAllocator
768 };
769
770 /// Get the kind of the allocation. This must match between allocation
771 /// and deallocation.
772 Kind getKind() const {
773 if (auto *NE = dyn_cast<CXXNewExpr>(AllocExpr))
774 return NE->isArray() ? ArrayNew : New;
775 assert(isa<CallExpr>(AllocExpr));
776 return StdAllocator;
777 }
778 };
779
780 struct DynAllocOrder {
781 bool operator()(DynamicAllocLValue L, DynamicAllocLValue R) const {
782 return L.getIndex() < R.getIndex();
783 }
784 };
785
786 /// EvalInfo - This is a private struct used by the evaluator to capture
787 /// information about a subexpression as it is folded. It retains information
788 /// about the AST context, but also maintains information about the folded
789 /// expression.
790 ///
791 /// If an expression could be evaluated, it is still possible it is not a C
792 /// "integer constant expression" or constant expression. If not, this struct
793 /// captures information about how and why not.
794 ///
795 /// One bit of information passed *into* the request for constant folding
796 /// indicates whether the subexpression is "evaluated" or not according to C
797 /// rules. For example, the RHS of (0 && foo()) is not evaluated. We can
798 /// evaluate the expression regardless of what the RHS is, but C only allows
799 /// certain things in certain situations.
800 class EvalInfo : public interp::State {
801 public:
802 ASTContext &Ctx;
803
804 /// EvalStatus - Contains information about the evaluation.
805 Expr::EvalStatus &EvalStatus;
806
807 /// CurrentCall - The top of the constexpr call stack.
808 CallStackFrame *CurrentCall;
809
810 /// CallStackDepth - The number of calls in the call stack right now.
811 unsigned CallStackDepth;
812
813 /// NextCallIndex - The next call index to assign.
814 unsigned NextCallIndex;
815
816 /// StepsLeft - The remaining number of evaluation steps we're permitted
817 /// to perform. This is essentially a limit for the number of statements
818 /// we will evaluate.
819 unsigned StepsLeft;
820
821 /// Enable the experimental new constant interpreter. If an expression is
822 /// not supported by the interpreter, an error is triggered.
823 bool EnableNewConstInterp;
824
825 /// BottomFrame - The frame in which evaluation started. This must be
826 /// initialized after CurrentCall and CallStackDepth.
827 CallStackFrame BottomFrame;
828
829 /// A stack of values whose lifetimes end at the end of some surrounding
830 /// evaluation frame.
832
833 /// EvaluatingDecl - This is the declaration whose initializer is being
834 /// evaluated, if any.
835 APValue::LValueBase EvaluatingDecl;
836
837 enum class EvaluatingDeclKind {
838 None,
839 /// We're evaluating the construction of EvaluatingDecl.
840 Ctor,
841 /// We're evaluating the destruction of EvaluatingDecl.
842 Dtor,
843 };
844 EvaluatingDeclKind IsEvaluatingDecl = EvaluatingDeclKind::None;
845
846 /// EvaluatingDeclValue - This is the value being constructed for the
847 /// declaration whose initializer is being evaluated, if any.
848 APValue *EvaluatingDeclValue;
849
850 /// Set of objects that are currently being constructed.
851 llvm::DenseMap<ObjectUnderConstruction, ConstructionPhase>
852 ObjectsUnderConstruction;
853
854 /// Current heap allocations, along with the location where each was
855 /// allocated. We use std::map here because we need stable addresses
856 /// for the stored APValues.
857 std::map<DynamicAllocLValue, DynAlloc, DynAllocOrder> HeapAllocs;
858
859 /// The number of heap allocations performed so far in this evaluation.
860 unsigned NumHeapAllocs = 0;
861
862 struct EvaluatingConstructorRAII {
863 EvalInfo &EI;
864 ObjectUnderConstruction Object;
865 bool DidInsert;
866 EvaluatingConstructorRAII(EvalInfo &EI, ObjectUnderConstruction Object,
867 bool HasBases)
868 : EI(EI), Object(Object) {
869 DidInsert =
870 EI.ObjectsUnderConstruction
871 .insert({Object, HasBases ? ConstructionPhase::Bases
872 : ConstructionPhase::AfterBases})
873 .second;
874 }
875 void finishedConstructingBases() {
876 EI.ObjectsUnderConstruction[Object] = ConstructionPhase::AfterBases;
877 }
878 void finishedConstructingFields() {
879 EI.ObjectsUnderConstruction[Object] = ConstructionPhase::AfterFields;
880 }
881 ~EvaluatingConstructorRAII() {
882 if (DidInsert) EI.ObjectsUnderConstruction.erase(Object);
883 }
884 };
885
886 struct EvaluatingDestructorRAII {
887 EvalInfo &EI;
888 ObjectUnderConstruction Object;
889 bool DidInsert;
890 EvaluatingDestructorRAII(EvalInfo &EI, ObjectUnderConstruction Object)
891 : EI(EI), Object(Object) {
892 DidInsert = EI.ObjectsUnderConstruction
893 .insert({Object, ConstructionPhase::Destroying})
894 .second;
895 }
896 void startedDestroyingBases() {
897 EI.ObjectsUnderConstruction[Object] =
898 ConstructionPhase::DestroyingBases;
899 }
900 ~EvaluatingDestructorRAII() {
901 if (DidInsert)
902 EI.ObjectsUnderConstruction.erase(Object);
903 }
904 };
905
906 ConstructionPhase
907 isEvaluatingCtorDtor(APValue::LValueBase Base,
909 return ObjectsUnderConstruction.lookup({Base, Path});
910 }
911
912 /// If we're currently speculatively evaluating, the outermost call stack
913 /// depth at which we can mutate state, otherwise 0.
914 unsigned SpeculativeEvaluationDepth = 0;
915
916 /// The current array initialization index, if we're performing array
917 /// initialization.
918 uint64_t ArrayInitIndex = -1;
919
920 /// HasActiveDiagnostic - Was the previous diagnostic stored? If so, further
921 /// notes attached to it will also be stored, otherwise they will not be.
922 bool HasActiveDiagnostic;
923
924 /// Have we emitted a diagnostic explaining why we couldn't constant
925 /// fold (not just why it's not strictly a constant expression)?
926 bool HasFoldFailureDiagnostic;
927
928 /// Whether we're checking that an expression is a potential constant
929 /// expression. If so, do not fail on constructs that could become constant
930 /// later on (such as a use of an undefined global).
931 bool CheckingPotentialConstantExpression = false;
932
933 /// Whether we're checking for an expression that has undefined behavior.
934 /// If so, we will produce warnings if we encounter an operation that is
935 /// always undefined.
936 ///
937 /// Note that we still need to evaluate the expression normally when this
938 /// is set; this is used when evaluating ICEs in C.
939 bool CheckingForUndefinedBehavior = false;
940
941 enum EvaluationMode {
942 /// Evaluate as a constant expression. Stop if we find that the expression
943 /// is not a constant expression.
944 EM_ConstantExpression,
945
946 /// Evaluate as a constant expression. Stop if we find that the expression
947 /// is not a constant expression. Some expressions can be retried in the
948 /// optimizer if we don't constant fold them here, but in an unevaluated
949 /// context we try to fold them immediately since the optimizer never
950 /// gets a chance to look at it.
951 EM_ConstantExpressionUnevaluated,
952
953 /// Fold the expression to a constant. Stop if we hit a side-effect that
954 /// we can't model.
955 EM_ConstantFold,
956
957 /// Evaluate in any way we know how. Don't worry about side-effects that
958 /// can't be modeled.
959 EM_IgnoreSideEffects,
960 } EvalMode;
961
962 /// Are we checking whether the expression is a potential constant
963 /// expression?
964 bool checkingPotentialConstantExpression() const override {
965 return CheckingPotentialConstantExpression;
966 }
967
968 /// Are we checking an expression for overflow?
969 // FIXME: We should check for any kind of undefined or suspicious behavior
970 // in such constructs, not just overflow.
971 bool checkingForUndefinedBehavior() const override {
972 return CheckingForUndefinedBehavior;
973 }
974
975 EvalInfo(const ASTContext &C, Expr::EvalStatus &S, EvaluationMode Mode)
976 : Ctx(const_cast<ASTContext &>(C)), EvalStatus(S), CurrentCall(nullptr),
977 CallStackDepth(0), NextCallIndex(1),
978 StepsLeft(C.getLangOpts().ConstexprStepLimit),
979 EnableNewConstInterp(C.getLangOpts().EnableNewConstInterp),
980 BottomFrame(*this, SourceLocation(), nullptr, nullptr, CallRef()),
981 EvaluatingDecl((const ValueDecl *)nullptr),
982 EvaluatingDeclValue(nullptr), HasActiveDiagnostic(false),
983 HasFoldFailureDiagnostic(false), EvalMode(Mode) {}
984
985 ~EvalInfo() {
986 discardCleanups();
987 }
988
989 ASTContext &getCtx() const override { return Ctx; }
990
991 void setEvaluatingDecl(APValue::LValueBase Base, APValue &Value,
992 EvaluatingDeclKind EDK = EvaluatingDeclKind::Ctor) {
993 EvaluatingDecl = Base;
994 IsEvaluatingDecl = EDK;
995 EvaluatingDeclValue = &Value;
996 }
997
998 bool CheckCallLimit(SourceLocation Loc) {
999 // Don't perform any constexpr calls (other than the call we're checking)
1000 // when checking a potential constant expression.
1001 if (checkingPotentialConstantExpression() && CallStackDepth > 1)
1002 return false;
1003 if (NextCallIndex == 0) {
1004 // NextCallIndex has wrapped around.
1005 FFDiag(Loc, diag::note_constexpr_call_limit_exceeded);
1006 return false;
1007 }
1008 if (CallStackDepth <= getLangOpts().ConstexprCallDepth)
1009 return true;
1010 FFDiag(Loc, diag::note_constexpr_depth_limit_exceeded)
1011 << getLangOpts().ConstexprCallDepth;
1012 return false;
1013 }
1014
1015 std::pair<CallStackFrame *, unsigned>
1016 getCallFrameAndDepth(unsigned CallIndex) {
1017 assert(CallIndex && "no call index in getCallFrameAndDepth");
1018 // We will eventually hit BottomFrame, which has Index 1, so Frame can't
1019 // be null in this loop.
1020 unsigned Depth = CallStackDepth;
1021 CallStackFrame *Frame = CurrentCall;
1022 while (Frame->Index > CallIndex) {
1023 Frame = Frame->Caller;
1024 --Depth;
1025 }
1026 if (Frame->Index == CallIndex)
1027 return {Frame, Depth};
1028 return {nullptr, 0};
1029 }
1030
1031 bool nextStep(const Stmt *S) {
1032 if (!StepsLeft) {
1033 FFDiag(S->getBeginLoc(), diag::note_constexpr_step_limit_exceeded);
1034 return false;
1035 }
1036 --StepsLeft;
1037 return true;
1038 }
1039
1040 APValue *createHeapAlloc(const Expr *E, QualType T, LValue &LV);
1041
1042 std::optional<DynAlloc *> lookupDynamicAlloc(DynamicAllocLValue DA) {
1043 std::optional<DynAlloc *> Result;
1044 auto It = HeapAllocs.find(DA);
1045 if (It != HeapAllocs.end())
1046 Result = &It->second;
1047 return Result;
1048 }
1049
1050 /// Get the allocated storage for the given parameter of the given call.
1051 APValue *getParamSlot(CallRef Call, const ParmVarDecl *PVD) {
1052 CallStackFrame *Frame = getCallFrameAndDepth(Call.CallIndex).first;
1053 return Frame ? Frame->getTemporary(Call.getOrigParam(PVD), Call.Version)
1054 : nullptr;
1055 }
1056
1057 /// Information about a stack frame for std::allocator<T>::[de]allocate.
1058 struct StdAllocatorCaller {
1059 unsigned FrameIndex;
1060 QualType ElemType;
1061 explicit operator bool() const { return FrameIndex != 0; };
1062 };
1063
1064 StdAllocatorCaller getStdAllocatorCaller(StringRef FnName) const {
1065 for (const CallStackFrame *Call = CurrentCall; Call != &BottomFrame;
1066 Call = Call->Caller) {
1067 const auto *MD = dyn_cast_or_null<CXXMethodDecl>(Call->Callee);
1068 if (!MD)
1069 continue;
1070 const IdentifierInfo *FnII = MD->getIdentifier();
1071 if (!FnII || !FnII->isStr(FnName))
1072 continue;
1073
1074 const auto *CTSD =
1075 dyn_cast<ClassTemplateSpecializationDecl>(MD->getParent());
1076 if (!CTSD)
1077 continue;
1078
1079 const IdentifierInfo *ClassII = CTSD->getIdentifier();
1080 const TemplateArgumentList &TAL = CTSD->getTemplateArgs();
1081 if (CTSD->isInStdNamespace() && ClassII &&
1082 ClassII->isStr("allocator") && TAL.size() >= 1 &&
1083 TAL[0].getKind() == TemplateArgument::Type)
1084 return {Call->Index, TAL[0].getAsType()};
1085 }
1086
1087 return {};
1088 }
1089
1090 void performLifetimeExtension() {
1091 // Disable the cleanups for lifetime-extended temporaries.
1092 llvm::erase_if(CleanupStack, [](Cleanup &C) {
1093 return !C.isDestroyedAtEndOf(ScopeKind::FullExpression);
1094 });
1095 }
1096
1097 /// Throw away any remaining cleanups at the end of evaluation. If any
1098 /// cleanups would have had a side-effect, note that as an unmodeled
1099 /// side-effect and return false. Otherwise, return true.
1100 bool discardCleanups() {
1101 for (Cleanup &C : CleanupStack) {
1102 if (C.hasSideEffect() && !noteSideEffect()) {
1103 CleanupStack.clear();
1104 return false;
1105 }
1106 }
1107 CleanupStack.clear();
1108 return true;
1109 }
1110
1111 private:
1112 interp::Frame *getCurrentFrame() override { return CurrentCall; }
1113 const interp::Frame *getBottomFrame() const override { return &BottomFrame; }
1114
1115 bool hasActiveDiagnostic() override { return HasActiveDiagnostic; }
1116 void setActiveDiagnostic(bool Flag) override { HasActiveDiagnostic = Flag; }
1117
1118 void setFoldFailureDiagnostic(bool Flag) override {
1119 HasFoldFailureDiagnostic = Flag;
1120 }
1121
1122 Expr::EvalStatus &getEvalStatus() const override { return EvalStatus; }
1123
1124 // If we have a prior diagnostic, it will be noting that the expression
1125 // isn't a constant expression. This diagnostic is more important,
1126 // unless we require this evaluation to produce a constant expression.
1127 //
1128 // FIXME: We might want to show both diagnostics to the user in
1129 // EM_ConstantFold mode.
1130 bool hasPriorDiagnostic() override {
1131 if (!EvalStatus.Diag->empty()) {
1132 switch (EvalMode) {
1133 case EM_ConstantFold:
1134 case EM_IgnoreSideEffects:
1135 if (!HasFoldFailureDiagnostic)
1136 break;
1137 // We've already failed to fold something. Keep that diagnostic.
1138 [[fallthrough]];
1139 case EM_ConstantExpression:
1140 case EM_ConstantExpressionUnevaluated:
1141 setActiveDiagnostic(false);
1142 return true;
1143 }
1144 }
1145 return false;
1146 }
1147
1148 unsigned getCallStackDepth() override { return CallStackDepth; }
1149
1150 public:
1151 /// Should we continue evaluation after encountering a side-effect that we
1152 /// couldn't model?
1153 bool keepEvaluatingAfterSideEffect() {
1154 switch (EvalMode) {
1155 case EM_IgnoreSideEffects:
1156 return true;
1157
1158 case EM_ConstantExpression:
1159 case EM_ConstantExpressionUnevaluated:
1160 case EM_ConstantFold:
1161 // By default, assume any side effect might be valid in some other
1162 // evaluation of this expression from a different context.
1163 return checkingPotentialConstantExpression() ||
1164 checkingForUndefinedBehavior();
1165 }
1166 llvm_unreachable("Missed EvalMode case");
1167 }
1168
1169 /// Note that we have had a side-effect, and determine whether we should
1170 /// keep evaluating.
1171 bool noteSideEffect() {
1172 EvalStatus.HasSideEffects = true;
1173 return keepEvaluatingAfterSideEffect();
1174 }
1175
1176 /// Should we continue evaluation after encountering undefined behavior?
1177 bool keepEvaluatingAfterUndefinedBehavior() {
1178 switch (EvalMode) {
1179 case EM_IgnoreSideEffects:
1180 case EM_ConstantFold:
1181 return true;
1182
1183 case EM_ConstantExpression:
1184 case EM_ConstantExpressionUnevaluated:
1185 return checkingForUndefinedBehavior();
1186 }
1187 llvm_unreachable("Missed EvalMode case");
1188 }
1189
1190 /// Note that we hit something that was technically undefined behavior, but
1191 /// that we can evaluate past it (such as signed overflow or floating-point
1192 /// division by zero.)
1193 bool noteUndefinedBehavior() override {
1194 EvalStatus.HasUndefinedBehavior = true;
1195 return keepEvaluatingAfterUndefinedBehavior();
1196 }
1197
1198 /// Should we continue evaluation as much as possible after encountering a
1199 /// construct which can't be reduced to a value?
1200 bool keepEvaluatingAfterFailure() const override {
1201 if (!StepsLeft)
1202 return false;
1203
1204 switch (EvalMode) {
1205 case EM_ConstantExpression:
1206 case EM_ConstantExpressionUnevaluated:
1207 case EM_ConstantFold:
1208 case EM_IgnoreSideEffects:
1209 return checkingPotentialConstantExpression() ||
1210 checkingForUndefinedBehavior();
1211 }
1212 llvm_unreachable("Missed EvalMode case");
1213 }
1214
1215 /// Notes that we failed to evaluate an expression that other expressions
1216 /// directly depend on, and determine if we should keep evaluating. This
1217 /// should only be called if we actually intend to keep evaluating.
1218 ///
1219 /// Call noteSideEffect() instead if we may be able to ignore the value that
1220 /// we failed to evaluate, e.g. if we failed to evaluate Foo() in:
1221 ///
1222 /// (Foo(), 1) // use noteSideEffect
1223 /// (Foo() || true) // use noteSideEffect
1224 /// Foo() + 1 // use noteFailure
1225 [[nodiscard]] bool noteFailure() {
1226 // Failure when evaluating some expression often means there is some
1227 // subexpression whose evaluation was skipped. Therefore, (because we
1228 // don't track whether we skipped an expression when unwinding after an
1229 // evaluation failure) every evaluation failure that bubbles up from a
1230 // subexpression implies that a side-effect has potentially happened. We
1231 // skip setting the HasSideEffects flag to true until we decide to
1232 // continue evaluating after that point, which happens here.
1233 bool KeepGoing = keepEvaluatingAfterFailure();
1234 EvalStatus.HasSideEffects |= KeepGoing;
1235 return KeepGoing;
1236 }
1237
1238 class ArrayInitLoopIndex {
1239 EvalInfo &Info;
1240 uint64_t OuterIndex;
1241
1242 public:
1243 ArrayInitLoopIndex(EvalInfo &Info)
1244 : Info(Info), OuterIndex(Info.ArrayInitIndex) {
1245 Info.ArrayInitIndex = 0;
1246 }
1247 ~ArrayInitLoopIndex() { Info.ArrayInitIndex = OuterIndex; }
1248
1249 operator uint64_t&() { return Info.ArrayInitIndex; }
1250 };
1251 };
1252
1253 /// Object used to treat all foldable expressions as constant expressions.
1254 struct FoldConstant {
1255 EvalInfo &Info;
1256 bool Enabled;
1257 bool HadNoPriorDiags;
1258 EvalInfo::EvaluationMode OldMode;
1259
1260 explicit FoldConstant(EvalInfo &Info, bool Enabled)
1261 : Info(Info),
1262 Enabled(Enabled),
1263 HadNoPriorDiags(Info.EvalStatus.Diag &&
1264 Info.EvalStatus.Diag->empty() &&
1265 !Info.EvalStatus.HasSideEffects),
1266 OldMode(Info.EvalMode) {
1267 if (Enabled)
1268 Info.EvalMode = EvalInfo::EM_ConstantFold;
1269 }
1270 void keepDiagnostics() { Enabled = false; }
1271 ~FoldConstant() {
1272 if (Enabled && HadNoPriorDiags && !Info.EvalStatus.Diag->empty() &&
1273 !Info.EvalStatus.HasSideEffects)
1274 Info.EvalStatus.Diag->clear();
1275 Info.EvalMode = OldMode;
1276 }
1277 };
1278
1279 /// RAII object used to set the current evaluation mode to ignore
1280 /// side-effects.
1281 struct IgnoreSideEffectsRAII {
1282 EvalInfo &Info;
1283 EvalInfo::EvaluationMode OldMode;
1284 explicit IgnoreSideEffectsRAII(EvalInfo &Info)
1285 : Info(Info), OldMode(Info.EvalMode) {
1286 Info.EvalMode = EvalInfo::EM_IgnoreSideEffects;
1287 }
1288
1289 ~IgnoreSideEffectsRAII() { Info.EvalMode = OldMode; }
1290 };
1291
1292 /// RAII object used to optionally suppress diagnostics and side-effects from
1293 /// a speculative evaluation.
1294 class SpeculativeEvaluationRAII {
1295 EvalInfo *Info = nullptr;
1296 Expr::EvalStatus OldStatus;
1297 unsigned OldSpeculativeEvaluationDepth;
1298
1299 void moveFromAndCancel(SpeculativeEvaluationRAII &&Other) {
1300 Info = Other.Info;
1301 OldStatus = Other.OldStatus;
1302 OldSpeculativeEvaluationDepth = Other.OldSpeculativeEvaluationDepth;
1303 Other.Info = nullptr;
1304 }
1305
1306 void maybeRestoreState() {
1307 if (!Info)
1308 return;
1309
1310 Info->EvalStatus = OldStatus;
1311 Info->SpeculativeEvaluationDepth = OldSpeculativeEvaluationDepth;
1312 }
1313
1314 public:
1315 SpeculativeEvaluationRAII() = default;
1316
1317 SpeculativeEvaluationRAII(
1318 EvalInfo &Info, SmallVectorImpl<PartialDiagnosticAt> *NewDiag = nullptr)
1319 : Info(&Info), OldStatus(Info.EvalStatus),
1320 OldSpeculativeEvaluationDepth(Info.SpeculativeEvaluationDepth) {
1321 Info.EvalStatus.Diag = NewDiag;
1322 Info.SpeculativeEvaluationDepth = Info.CallStackDepth + 1;
1323 }
1324
1325 SpeculativeEvaluationRAII(const SpeculativeEvaluationRAII &Other) = delete;
1326 SpeculativeEvaluationRAII(SpeculativeEvaluationRAII &&Other) {
1327 moveFromAndCancel(std::move(Other));
1328 }
1329
1330 SpeculativeEvaluationRAII &operator=(SpeculativeEvaluationRAII &&Other) {
1331 maybeRestoreState();
1332 moveFromAndCancel(std::move(Other));
1333 return *this;
1334 }
1335
1336 ~SpeculativeEvaluationRAII() { maybeRestoreState(); }
1337 };
1338
1339 /// RAII object wrapping a full-expression or block scope, and handling
1340 /// the ending of the lifetime of temporaries created within it.
1341 template<ScopeKind Kind>
1342 class ScopeRAII {
1343 EvalInfo &Info;
1344 unsigned OldStackSize;
1345 public:
1346 ScopeRAII(EvalInfo &Info)
1347 : Info(Info), OldStackSize(Info.CleanupStack.size()) {
1348 // Push a new temporary version. This is needed to distinguish between
1349 // temporaries created in different iterations of a loop.
1350 Info.CurrentCall->pushTempVersion();
1351 }
1352 bool destroy(bool RunDestructors = true) {
1353 bool OK = cleanup(Info, RunDestructors, OldStackSize);
1354 OldStackSize = -1U;
1355 return OK;
1356 }
1357 ~ScopeRAII() {
1358 if (OldStackSize != -1U)
1359 destroy(false);
1360 // Body moved to a static method to encourage the compiler to inline away
1361 // instances of this class.
1362 Info.CurrentCall->popTempVersion();
1363 }
1364 private:
1365 static bool cleanup(EvalInfo &Info, bool RunDestructors,
1366 unsigned OldStackSize) {
1367 assert(OldStackSize <= Info.CleanupStack.size() &&
1368 "running cleanups out of order?");
1369
1370 // Run all cleanups for a block scope, and non-lifetime-extended cleanups
1371 // for a full-expression scope.
1372 bool Success = true;
1373 for (unsigned I = Info.CleanupStack.size(); I > OldStackSize; --I) {
1374 if (Info.CleanupStack[I - 1].isDestroyedAtEndOf(Kind)) {
1375 if (!Info.CleanupStack[I - 1].endLifetime(Info, RunDestructors)) {
1376 Success = false;
1377 break;
1378 }
1379 }
1380 }
1381
1382 // Compact any retained cleanups.
1383 auto NewEnd = Info.CleanupStack.begin() + OldStackSize;
1384 if (Kind != ScopeKind::Block)
1385 NewEnd =
1386 std::remove_if(NewEnd, Info.CleanupStack.end(), [](Cleanup &C) {
1387 return C.isDestroyedAtEndOf(Kind);
1388 });
1389 Info.CleanupStack.erase(NewEnd, Info.CleanupStack.end());
1390 return Success;
1391 }
1392 };
1393 typedef ScopeRAII<ScopeKind::Block> BlockScopeRAII;
1394 typedef ScopeRAII<ScopeKind::FullExpression> FullExpressionRAII;
1395 typedef ScopeRAII<ScopeKind::Call> CallScopeRAII;
1396}
1397
1398bool SubobjectDesignator::checkSubobject(EvalInfo &Info, const Expr *E,
1399 CheckSubobjectKind CSK) {
1400 if (Invalid)
1401 return false;
1402 if (isOnePastTheEnd()) {
1403 Info.CCEDiag(E, diag::note_constexpr_past_end_subobject)
1404 << CSK;
1405 setInvalid();
1406 return false;
1407 }
1408 // Note, we do not diagnose if isMostDerivedAnUnsizedArray(), because there
1409 // must actually be at least one array element; even a VLA cannot have a
1410 // bound of zero. And if our index is nonzero, we already had a CCEDiag.
1411 return true;
1412}
1413
1414void SubobjectDesignator::diagnoseUnsizedArrayPointerArithmetic(EvalInfo &Info,
1415 const Expr *E) {
1416 Info.CCEDiag(E, diag::note_constexpr_unsized_array_indexed);
1417 // Do not set the designator as invalid: we can represent this situation,
1418 // and correct handling of __builtin_object_size requires us to do so.
1419}
1420
1421void SubobjectDesignator::diagnosePointerArithmetic(EvalInfo &Info,
1422 const Expr *E,
1423 const APSInt &N) {
1424 // If we're complaining, we must be able to statically determine the size of
1425 // the most derived array.
1426 if (MostDerivedPathLength == Entries.size() && MostDerivedIsArrayElement)
1427 Info.CCEDiag(E, diag::note_constexpr_array_index)
1428 << N << /*array*/ 0
1429 << static_cast<unsigned>(getMostDerivedArraySize());
1430 else
1431 Info.CCEDiag(E, diag::note_constexpr_array_index)
1432 << N << /*non-array*/ 1;
1433 setInvalid();
1434}
1435
1436CallStackFrame::CallStackFrame(EvalInfo &Info, SourceLocation CallLoc,
1437 const FunctionDecl *Callee, const LValue *This,
1438 CallRef Call)
1439 : Info(Info), Caller(Info.CurrentCall), Callee(Callee), This(This),
1440 Arguments(Call), CallLoc(CallLoc), Index(Info.NextCallIndex++) {
1441 Info.CurrentCall = this;
1442 ++Info.CallStackDepth;
1443}
1444
1445CallStackFrame::~CallStackFrame() {
1446 assert(Info.CurrentCall == this && "calls retired out of order");
1447 --Info.CallStackDepth;
1448 Info.CurrentCall = Caller;
1449}
1450
1451static bool isRead(AccessKinds AK) {
1452 return AK == AK_Read || AK == AK_ReadObjectRepresentation;
1453}
1454
1456 switch (AK) {
1457 case AK_Read:
1459 case AK_MemberCall:
1460 case AK_DynamicCast:
1461 case AK_TypeId:
1462 return false;
1463 case AK_Assign:
1464 case AK_Increment:
1465 case AK_Decrement:
1466 case AK_Construct:
1467 case AK_Destroy:
1468 return true;
1469 }
1470 llvm_unreachable("unknown access kind");
1471}
1472
1473static bool isAnyAccess(AccessKinds AK) {
1474 return isRead(AK) || isModification(AK);
1475}
1476
1477/// Is this an access per the C++ definition?
1479 return isAnyAccess(AK) && AK != AK_Construct && AK != AK_Destroy;
1480}
1481
1482/// Is this kind of axcess valid on an indeterminate object value?
1484 switch (AK) {
1485 case AK_Read:
1486 case AK_Increment:
1487 case AK_Decrement:
1488 // These need the object's value.
1489 return false;
1490
1492 case AK_Assign:
1493 case AK_Construct:
1494 case AK_Destroy:
1495 // Construction and destruction don't need the value.
1496 return true;
1497
1498 case AK_MemberCall:
1499 case AK_DynamicCast:
1500 case AK_TypeId:
1501 // These aren't really meaningful on scalars.
1502 return true;
1503 }
1504 llvm_unreachable("unknown access kind");
1505}
1506
1507namespace {
1508 struct ComplexValue {
1509 private:
1510 bool IsInt;
1511
1512 public:
1513 APSInt IntReal, IntImag;
1514 APFloat FloatReal, FloatImag;
1515
1516 ComplexValue() : FloatReal(APFloat::Bogus()), FloatImag(APFloat::Bogus()) {}
1517
1518 void makeComplexFloat() { IsInt = false; }
1519 bool isComplexFloat() const { return !IsInt; }
1520 APFloat &getComplexFloatReal() { return FloatReal; }
1521 APFloat &getComplexFloatImag() { return FloatImag; }
1522
1523 void makeComplexInt() { IsInt = true; }
1524 bool isComplexInt() const { return IsInt; }
1525 APSInt &getComplexIntReal() { return IntReal; }
1526 APSInt &getComplexIntImag() { return IntImag; }
1527
1528 void moveInto(APValue &v) const {
1529 if (isComplexFloat())
1530 v = APValue(FloatReal, FloatImag);
1531 else
1532 v = APValue(IntReal, IntImag);
1533 }
1534 void setFrom(const APValue &v) {
1535 assert(v.isComplexFloat() || v.isComplexInt());
1536 if (v.isComplexFloat()) {
1537 makeComplexFloat();
1538 FloatReal = v.getComplexFloatReal();
1539 FloatImag = v.getComplexFloatImag();
1540 } else {
1541 makeComplexInt();
1542 IntReal = v.getComplexIntReal();
1543 IntImag = v.getComplexIntImag();
1544 }
1545 }
1546 };
1547
1548 struct LValue {
1551 SubobjectDesignator Designator;
1552 bool IsNullPtr : 1;
1553 bool InvalidBase : 1;
1554
1555 const APValue::LValueBase getLValueBase() const { return Base; }
1556 CharUnits &getLValueOffset() { return Offset; }
1557 const CharUnits &getLValueOffset() const { return Offset; }
1558 SubobjectDesignator &getLValueDesignator() { return Designator; }
1559 const SubobjectDesignator &getLValueDesignator() const { return Designator;}
1560 bool isNullPointer() const { return IsNullPtr;}
1561
1562 unsigned getLValueCallIndex() const { return Base.getCallIndex(); }
1563 unsigned getLValueVersion() const { return Base.getVersion(); }
1564
1565 void moveInto(APValue &V) const {
1566 if (Designator.Invalid)
1567 V = APValue(Base, Offset, APValue::NoLValuePath(), IsNullPtr);
1568 else {
1569 assert(!InvalidBase && "APValues can't handle invalid LValue bases");
1570 V = APValue(Base, Offset, Designator.Entries,
1571 Designator.IsOnePastTheEnd, IsNullPtr);
1572 }
1573 }
1574 void setFrom(ASTContext &Ctx, const APValue &V) {
1575 assert(V.isLValue() && "Setting LValue from a non-LValue?");
1576 Base = V.getLValueBase();
1577 Offset = V.getLValueOffset();
1578 InvalidBase = false;
1579 Designator = SubobjectDesignator(Ctx, V);
1580 IsNullPtr = V.isNullPointer();
1581 }
1582
1583 void set(APValue::LValueBase B, bool BInvalid = false) {
1584#ifndef NDEBUG
1585 // We only allow a few types of invalid bases. Enforce that here.
1586 if (BInvalid) {
1587 const auto *E = B.get<const Expr *>();
1588 assert((isa<MemberExpr>(E) || tryUnwrapAllocSizeCall(E)) &&
1589 "Unexpected type of invalid base");
1590 }
1591#endif
1592
1593 Base = B;
1595 InvalidBase = BInvalid;
1596 Designator = SubobjectDesignator(getType(B));
1597 IsNullPtr = false;
1598 }
1599
1600 void setNull(ASTContext &Ctx, QualType PointerTy) {
1601 Base = (const ValueDecl *)nullptr;
1602 Offset =
1604 InvalidBase = false;
1605 Designator = SubobjectDesignator(PointerTy->getPointeeType());
1606 IsNullPtr = true;
1607 }
1608
1609 void setInvalid(APValue::LValueBase B, unsigned I = 0) {
1610 set(B, true);
1611 }
1612
1613 std::string toString(ASTContext &Ctx, QualType T) const {
1614 APValue Printable;
1615 moveInto(Printable);
1616 return Printable.getAsString(Ctx, T);
1617 }
1618
1619 private:
1620 // Check that this LValue is not based on a null pointer. If it is, produce
1621 // a diagnostic and mark the designator as invalid.
1622 template <typename GenDiagType>
1623 bool checkNullPointerDiagnosingWith(const GenDiagType &GenDiag) {
1624 if (Designator.Invalid)
1625 return false;
1626 if (IsNullPtr) {
1627 GenDiag();
1628 Designator.setInvalid();
1629 return false;
1630 }
1631 return true;
1632 }
1633
1634 public:
1635 bool checkNullPointer(EvalInfo &Info, const Expr *E,
1636 CheckSubobjectKind CSK) {
1637 return checkNullPointerDiagnosingWith([&Info, E, CSK] {
1638 Info.CCEDiag(E, diag::note_constexpr_null_subobject) << CSK;
1639 });
1640 }
1641
1642 bool checkNullPointerForFoldAccess(EvalInfo &Info, const Expr *E,
1643 AccessKinds AK) {
1644 return checkNullPointerDiagnosingWith([&Info, E, AK] {
1645 Info.FFDiag(E, diag::note_constexpr_access_null) << AK;
1646 });
1647 }
1648
1649 // Check this LValue refers to an object. If not, set the designator to be
1650 // invalid and emit a diagnostic.
1651 bool checkSubobject(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK) {
1652 return (CSK == CSK_ArrayToPointer || checkNullPointer(Info, E, CSK)) &&
1653 Designator.checkSubobject(Info, E, CSK);
1654 }
1655
1656 void addDecl(EvalInfo &Info, const Expr *E,
1657 const Decl *D, bool Virtual = false) {
1658 if (checkSubobject(Info, E, isa<FieldDecl>(D) ? CSK_Field : CSK_Base))
1659 Designator.addDeclUnchecked(D, Virtual);
1660 }
1661 void addUnsizedArray(EvalInfo &Info, const Expr *E, QualType ElemTy) {
1662 if (!Designator.Entries.empty()) {
1663 Info.CCEDiag(E, diag::note_constexpr_unsupported_unsized_array);
1664 Designator.setInvalid();
1665 return;
1666 }
1667 if (checkSubobject(Info, E, CSK_ArrayToPointer)) {
1668 assert(getType(Base)->isPointerType() || getType(Base)->isArrayType());
1669 Designator.FirstEntryIsAnUnsizedArray = true;
1670 Designator.addUnsizedArrayUnchecked(ElemTy);
1671 }
1672 }
1673 void addArray(EvalInfo &Info, const Expr *E, const ConstantArrayType *CAT) {
1674 if (checkSubobject(Info, E, CSK_ArrayToPointer))
1675 Designator.addArrayUnchecked(CAT);
1676 }
1677 void addComplex(EvalInfo &Info, const Expr *E, QualType EltTy, bool Imag) {
1678 if (checkSubobject(Info, E, Imag ? CSK_Imag : CSK_Real))
1679 Designator.addComplexUnchecked(EltTy, Imag);
1680 }
1681 void clearIsNullPointer() {
1682 IsNullPtr = false;
1683 }
1684 void adjustOffsetAndIndex(EvalInfo &Info, const Expr *E,
1685 const APSInt &Index, CharUnits ElementSize) {
1686 // An index of 0 has no effect. (In C, adding 0 to a null pointer is UB,
1687 // but we're not required to diagnose it and it's valid in C++.)
1688 if (!Index)
1689 return;
1690
1691 // Compute the new offset in the appropriate width, wrapping at 64 bits.
1692 // FIXME: When compiling for a 32-bit target, we should use 32-bit
1693 // offsets.
1694 uint64_t Offset64 = Offset.getQuantity();
1695 uint64_t ElemSize64 = ElementSize.getQuantity();
1696 uint64_t Index64 = Index.extOrTrunc(64).getZExtValue();
1697 Offset = CharUnits::fromQuantity(Offset64 + ElemSize64 * Index64);
1698
1699 if (checkNullPointer(Info, E, CSK_ArrayIndex))
1700 Designator.adjustIndex(Info, E, Index);
1701 clearIsNullPointer();
1702 }
1703 void adjustOffset(CharUnits N) {
1704 Offset += N;
1705 if (N.getQuantity())
1706 clearIsNullPointer();
1707 }
1708 };
1709
1710 struct MemberPtr {
1711 MemberPtr() {}
1712 explicit MemberPtr(const ValueDecl *Decl)
1713 : DeclAndIsDerivedMember(Decl, false) {}
1714
1715 /// The member or (direct or indirect) field referred to by this member
1716 /// pointer, or 0 if this is a null member pointer.
1717 const ValueDecl *getDecl() const {
1718 return DeclAndIsDerivedMember.getPointer();
1719 }
1720 /// Is this actually a member of some type derived from the relevant class?
1721 bool isDerivedMember() const {
1722 return DeclAndIsDerivedMember.getInt();
1723 }
1724 /// Get the class which the declaration actually lives in.
1725 const CXXRecordDecl *getContainingRecord() const {
1726 return cast<CXXRecordDecl>(
1727 DeclAndIsDerivedMember.getPointer()->getDeclContext());
1728 }
1729
1730 void moveInto(APValue &V) const {
1731 V = APValue(getDecl(), isDerivedMember(), Path);
1732 }
1733 void setFrom(const APValue &V) {
1734 assert(V.isMemberPointer());
1735 DeclAndIsDerivedMember.setPointer(V.getMemberPointerDecl());
1736 DeclAndIsDerivedMember.setInt(V.isMemberPointerToDerivedMember());
1737 Path.clear();
1738 ArrayRef<const CXXRecordDecl*> P = V.getMemberPointerPath();
1739 Path.insert(Path.end(), P.begin(), P.end());
1740 }
1741
1742 /// DeclAndIsDerivedMember - The member declaration, and a flag indicating
1743 /// whether the member is a member of some class derived from the class type
1744 /// of the member pointer.
1745 llvm::PointerIntPair<const ValueDecl*, 1, bool> DeclAndIsDerivedMember;
1746 /// Path - The path of base/derived classes from the member declaration's
1747 /// class (exclusive) to the class type of the member pointer (inclusive).
1749
1750 /// Perform a cast towards the class of the Decl (either up or down the
1751 /// hierarchy).
1752 bool castBack(const CXXRecordDecl *Class) {
1753 assert(!Path.empty());
1754 const CXXRecordDecl *Expected;
1755 if (Path.size() >= 2)
1756 Expected = Path[Path.size() - 2];
1757 else
1758 Expected = getContainingRecord();
1759 if (Expected->getCanonicalDecl() != Class->getCanonicalDecl()) {
1760 // C++11 [expr.static.cast]p12: In a conversion from (D::*) to (B::*),
1761 // if B does not contain the original member and is not a base or
1762 // derived class of the class containing the original member, the result
1763 // of the cast is undefined.
1764 // C++11 [conv.mem]p2 does not cover this case for a cast from (B::*) to
1765 // (D::*). We consider that to be a language defect.
1766 return false;
1767 }
1768 Path.pop_back();
1769 return true;
1770 }
1771 /// Perform a base-to-derived member pointer cast.
1772 bool castToDerived(const CXXRecordDecl *Derived) {
1773 if (!getDecl())
1774 return true;
1775 if (!isDerivedMember()) {
1776 Path.push_back(Derived);
1777 return true;
1778 }
1779 if (!castBack(Derived))
1780 return false;
1781 if (Path.empty())
1782 DeclAndIsDerivedMember.setInt(false);
1783 return true;
1784 }
1785 /// Perform a derived-to-base member pointer cast.
1786 bool castToBase(const CXXRecordDecl *Base) {
1787 if (!getDecl())
1788 return true;
1789 if (Path.empty())
1790 DeclAndIsDerivedMember.setInt(true);
1791 if (isDerivedMember()) {
1792 Path.push_back(Base);
1793 return true;
1794 }
1795 return castBack(Base);
1796 }
1797 };
1798
1799 /// Compare two member pointers, which are assumed to be of the same type.
1800 static bool operator==(const MemberPtr &LHS, const MemberPtr &RHS) {
1801 if (!LHS.getDecl() || !RHS.getDecl())
1802 return !LHS.getDecl() && !RHS.getDecl();
1803 if (LHS.getDecl()->getCanonicalDecl() != RHS.getDecl()->getCanonicalDecl())
1804 return false;
1805 return LHS.Path == RHS.Path;
1806 }
1807}
1808
1809static bool Evaluate(APValue &Result, EvalInfo &Info, const Expr *E);
1810static bool EvaluateInPlace(APValue &Result, EvalInfo &Info,
1811 const LValue &This, const Expr *E,
1812 bool AllowNonLiteralTypes = false);
1813static bool EvaluateLValue(const Expr *E, LValue &Result, EvalInfo &Info,
1814 bool InvalidBaseOK = false);
1815static bool EvaluatePointer(const Expr *E, LValue &Result, EvalInfo &Info,
1816 bool InvalidBaseOK = false);
1817static bool EvaluateMemberPointer(const Expr *E, MemberPtr &Result,
1818 EvalInfo &Info);
1819static bool EvaluateTemporary(const Expr *E, LValue &Result, EvalInfo &Info);
1820static bool EvaluateInteger(const Expr *E, APSInt &Result, EvalInfo &Info);
1821static bool EvaluateIntegerOrLValue(const Expr *E, APValue &Result,
1822 EvalInfo &Info);
1823static bool EvaluateFloat(const Expr *E, APFloat &Result, EvalInfo &Info);
1824static bool EvaluateComplex(const Expr *E, ComplexValue &Res, EvalInfo &Info);
1825static bool EvaluateAtomic(const Expr *E, const LValue *This, APValue &Result,
1826 EvalInfo &Info);
1827static bool EvaluateAsRValue(EvalInfo &Info, const Expr *E, APValue &Result);
1828static bool EvaluateBuiltinStrLen(const Expr *E, uint64_t &Result,
1829 EvalInfo &Info);
1830
1831/// Evaluate an integer or fixed point expression into an APResult.
1832static bool EvaluateFixedPointOrInteger(const Expr *E, APFixedPoint &Result,
1833 EvalInfo &Info);
1834
1835/// Evaluate only a fixed point expression into an APResult.
1836static bool EvaluateFixedPoint(const Expr *E, APFixedPoint &Result,
1837 EvalInfo &Info);
1838
1839//===----------------------------------------------------------------------===//
1840// Misc utilities
1841//===----------------------------------------------------------------------===//
1842
1843/// Negate an APSInt in place, converting it to a signed form if necessary, and
1844/// preserving its value (by extending by up to one bit as needed).
1845static void negateAsSigned(APSInt &Int) {
1846 if (Int.isUnsigned() || Int.isMinSignedValue()) {
1847 Int = Int.extend(Int.getBitWidth() + 1);
1848 Int.setIsSigned(true);
1849 }
1850 Int = -Int;
1851}
1852
1853template<typename KeyT>
1854APValue &CallStackFrame::createTemporary(const KeyT *Key, QualType T,
1855 ScopeKind Scope, LValue &LV) {
1856 unsigned Version = getTempVersion();
1857 APValue::LValueBase Base(Key, Index, Version);
1858 LV.set(Base);
1859 return createLocal(Base, Key, T, Scope);
1860}
1861
1862/// Allocate storage for a parameter of a function call made in this frame.
1863APValue &CallStackFrame::createParam(CallRef Args, const ParmVarDecl *PVD,
1864 LValue &LV) {
1865 assert(Args.CallIndex == Index && "creating parameter in wrong frame");
1866 APValue::LValueBase Base(PVD, Index, Args.Version);
1867 LV.set(Base);
1868 // We always destroy parameters at the end of the call, even if we'd allow
1869 // them to live to the end of the full-expression at runtime, in order to
1870 // give portable results and match other compilers.
1871 return createLocal(Base, PVD, PVD->getType(), ScopeKind::Call);
1872}
1873
1874APValue &CallStackFrame::createLocal(APValue::LValueBase Base, const void *Key,
1875 QualType T, ScopeKind Scope) {
1876 assert(Base.getCallIndex() == Index && "lvalue for wrong frame");
1877 unsigned Version = Base.getVersion();
1878 APValue &Result = Temporaries[MapKeyTy(Key, Version)];
1879 assert(Result.isAbsent() && "local created multiple times");
1880
1881 // If we're creating a local immediately in the operand of a speculative
1882 // evaluation, don't register a cleanup to be run outside the speculative
1883 // evaluation context, since we won't actually be able to initialize this
1884 // object.
1885 if (Index <= Info.SpeculativeEvaluationDepth) {
1886 if (T.isDestructedType())
1887 Info.noteSideEffect();
1888 } else {
1889 Info.CleanupStack.push_back(Cleanup(&Result, Base, T, Scope));
1890 }
1891 return Result;
1892}
1893
1894APValue *EvalInfo::createHeapAlloc(const Expr *E, QualType T, LValue &LV) {
1895 if (NumHeapAllocs > DynamicAllocLValue::getMaxIndex()) {
1896 FFDiag(E, diag::note_constexpr_heap_alloc_limit_exceeded);
1897 return nullptr;
1898 }
1899
1900 DynamicAllocLValue DA(NumHeapAllocs++);
1902 auto Result = HeapAllocs.emplace(std::piecewise_construct,
1903 std::forward_as_tuple(DA), std::tuple<>());
1904 assert(Result.second && "reused a heap alloc index?");
1905 Result.first->second.AllocExpr = E;
1906 return &Result.first->second.Value;
1907}
1908
1909/// Produce a string describing the given constexpr call.
1910void CallStackFrame::describe(raw_ostream &Out) {
1911 unsigned ArgIndex = 0;
1912 bool IsMemberCall = isa<CXXMethodDecl>(Callee) &&
1913 !isa<CXXConstructorDecl>(Callee) &&
1914 cast<CXXMethodDecl>(Callee)->isInstance();
1915
1916 if (!IsMemberCall)
1917 Out << *Callee << '(';
1918
1919 if (This && IsMemberCall) {
1920 APValue Val;
1921 This->moveInto(Val);
1922 Val.printPretty(Out, Info.Ctx,
1923 This->Designator.MostDerivedType);
1924 // FIXME: Add parens around Val if needed.
1925 Out << "->" << *Callee << '(';
1926 IsMemberCall = false;
1927 }
1928
1929 for (FunctionDecl::param_const_iterator I = Callee->param_begin(),
1930 E = Callee->param_end(); I != E; ++I, ++ArgIndex) {
1931 if (ArgIndex > (unsigned)IsMemberCall)
1932 Out << ", ";
1933
1934 const ParmVarDecl *Param = *I;
1935 APValue *V = Info.getParamSlot(Arguments, Param);
1936 if (V)
1937 V->printPretty(Out, Info.Ctx, Param->getType());
1938 else
1939 Out << "<...>";
1940
1941 if (ArgIndex == 0 && IsMemberCall)
1942 Out << "->" << *Callee << '(';
1943 }
1944
1945 Out << ')';
1946}
1947
1948/// Evaluate an expression to see if it had side-effects, and discard its
1949/// result.
1950/// \return \c true if the caller should keep evaluating.
1951static bool EvaluateIgnoredValue(EvalInfo &Info, const Expr *E) {
1952 assert(!E->isValueDependent());
1953 APValue Scratch;
1954 if (!Evaluate(Scratch, Info, E))
1955 // We don't need the value, but we might have skipped a side effect here.
1956 return Info.noteSideEffect();
1957 return true;
1958}
1959
1960/// Should this call expression be treated as a no-op?
1961static bool IsNoOpCall(const CallExpr *E) {
1962 unsigned Builtin = E->getBuiltinCallee();
1963 return (Builtin == Builtin::BI__builtin___CFStringMakeConstantString ||
1964 Builtin == Builtin::BI__builtin___NSStringMakeConstantString ||
1965 Builtin == Builtin::BI__builtin_function_start);
1966}
1967
1969 // C++11 [expr.const]p3 An address constant expression is a prvalue core
1970 // constant expression of pointer type that evaluates to...
1971
1972 // ... a null pointer value, or a prvalue core constant expression of type
1973 // std::nullptr_t.
1974 if (!B) return true;
1975
1976 if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) {
1977 // ... the address of an object with static storage duration,
1978 if (const VarDecl *VD = dyn_cast<VarDecl>(D))
1979 return VD->hasGlobalStorage();
1980 if (isa<TemplateParamObjectDecl>(D))
1981 return true;
1982 // ... the address of a function,
1983 // ... the address of a GUID [MS extension],
1984 // ... the address of an unnamed global constant
1985 return isa<FunctionDecl, MSGuidDecl, UnnamedGlobalConstantDecl>(D);
1986 }
1987
1988 if (B.is<TypeInfoLValue>() || B.is<DynamicAllocLValue>())
1989 return true;
1990
1991 const Expr *E = B.get<const Expr*>();
1992 switch (E->getStmtClass()) {
1993 default:
1994 return false;
1995 case Expr::CompoundLiteralExprClass: {
1996 const CompoundLiteralExpr *CLE = cast<CompoundLiteralExpr>(E);
1997 return CLE->isFileScope() && CLE->isLValue();
1998 }
1999 case Expr::MaterializeTemporaryExprClass:
2000 // A materialized temporary might have been lifetime-extended to static
2001 // storage duration.
2002 return cast<MaterializeTemporaryExpr>(E)->getStorageDuration() == SD_Static;
2003 // A string literal has static storage duration.
2004 case Expr::StringLiteralClass:
2005 case Expr::PredefinedExprClass:
2006 case Expr::ObjCStringLiteralClass:
2007 case Expr::ObjCEncodeExprClass:
2008 return true;
2009 case Expr::ObjCBoxedExprClass:
2010 return cast<ObjCBoxedExpr>(E)->isExpressibleAsConstantInitializer();
2011 case Expr::CallExprClass:
2012 return IsNoOpCall(cast<CallExpr>(E));
2013 // For GCC compatibility, &&label has static storage duration.
2014 case Expr::AddrLabelExprClass:
2015 return true;
2016 // A Block literal expression may be used as the initialization value for
2017 // Block variables at global or local static scope.
2018 case Expr::BlockExprClass:
2019 return !cast<BlockExpr>(E)->getBlockDecl()->hasCaptures();
2020 // The APValue generated from a __builtin_source_location will be emitted as a
2021 // literal.
2022 case Expr::SourceLocExprClass:
2023 return true;
2024 case Expr::ImplicitValueInitExprClass:
2025 // FIXME:
2026 // We can never form an lvalue with an implicit value initialization as its
2027 // base through expression evaluation, so these only appear in one case: the
2028 // implicit variable declaration we invent when checking whether a constexpr
2029 // constructor can produce a constant expression. We must assume that such
2030 // an expression might be a global lvalue.
2031 return true;
2032 }
2033}
2034
2035static const ValueDecl *GetLValueBaseDecl(const LValue &LVal) {
2036 return LVal.Base.dyn_cast<const ValueDecl*>();
2037}
2038
2039static bool IsLiteralLValue(const LValue &Value) {
2040 if (Value.getLValueCallIndex())
2041 return false;
2042 const Expr *E = Value.Base.dyn_cast<const Expr*>();
2043 return E && !isa<MaterializeTemporaryExpr>(E);
2044}
2045
2046static bool IsWeakLValue(const LValue &Value) {
2048 return Decl && Decl->isWeak();
2049}
2050
2051static bool isZeroSized(const LValue &Value) {
2053 if (Decl && isa<VarDecl>(Decl)) {
2054 QualType Ty = Decl->getType();
2055 if (Ty->isArrayType())
2056 return Ty->isIncompleteType() ||
2057 Decl->getASTContext().getTypeSize(Ty) == 0;
2058 }
2059 return false;
2060}
2061
2062static bool HasSameBase(const LValue &A, const LValue &B) {
2063 if (!A.getLValueBase())
2064 return !B.getLValueBase();
2065 if (!B.getLValueBase())
2066 return false;
2067
2068 if (A.getLValueBase().getOpaqueValue() !=
2069 B.getLValueBase().getOpaqueValue())
2070 return false;
2071
2072 return A.getLValueCallIndex() == B.getLValueCallIndex() &&
2073 A.getLValueVersion() == B.getLValueVersion();
2074}
2075
2076static void NoteLValueLocation(EvalInfo &Info, APValue::LValueBase Base) {
2077 assert(Base && "no location for a null lvalue");
2078 const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>();
2079
2080 // For a parameter, find the corresponding call stack frame (if it still
2081 // exists), and point at the parameter of the function definition we actually
2082 // invoked.
2083 if (auto *PVD = dyn_cast_or_null<ParmVarDecl>(VD)) {
2084 unsigned Idx = PVD->getFunctionScopeIndex();
2085 for (CallStackFrame *F = Info.CurrentCall; F; F = F->Caller) {
2086 if (F->Arguments.CallIndex == Base.getCallIndex() &&
2087 F->Arguments.Version == Base.getVersion() && F->Callee &&
2088 Idx < F->Callee->getNumParams()) {
2089 VD = F->Callee->getParamDecl(Idx);
2090 break;
2091 }
2092 }
2093 }
2094
2095 if (VD)
2096 Info.Note(VD->getLocation(), diag::note_declared_at);
2097 else if (const Expr *E = Base.dyn_cast<const Expr*>())
2098 Info.Note(E->getExprLoc(), diag::note_constexpr_temporary_here);
2099 else if (DynamicAllocLValue DA = Base.dyn_cast<DynamicAllocLValue>()) {
2100 // FIXME: Produce a note for dangling pointers too.
2101 if (std::optional<DynAlloc *> Alloc = Info.lookupDynamicAlloc(DA))
2102 Info.Note((*Alloc)->AllocExpr->getExprLoc(),
2103 diag::note_constexpr_dynamic_alloc_here);
2104 }
2105 // We have no information to show for a typeid(T) object.
2106}
2107
2111};
2112
2113/// Materialized temporaries that we've already checked to determine if they're
2114/// initializsed by a constant expression.
2117
2119 EvalInfo &Info, SourceLocation DiagLoc,
2120 QualType Type, const APValue &Value,
2121 ConstantExprKind Kind,
2122 const FieldDecl *SubobjectDecl,
2123 CheckedTemporaries &CheckedTemps);
2124
2125/// Check that this reference or pointer core constant expression is a valid
2126/// value for an address or reference constant expression. Return true if we
2127/// can fold this expression, whether or not it's a constant expression.
2128static bool CheckLValueConstantExpression(EvalInfo &Info, SourceLocation Loc,
2129 QualType Type, const LValue &LVal,
2130 ConstantExprKind Kind,
2131 CheckedTemporaries &CheckedTemps) {
2132 bool IsReferenceType = Type->isReferenceType();
2133
2134 APValue::LValueBase Base = LVal.getLValueBase();
2135 const SubobjectDesignator &Designator = LVal.getLValueDesignator();
2136
2137 const Expr *BaseE = Base.dyn_cast<const Expr *>();
2138 const ValueDecl *BaseVD = Base.dyn_cast<const ValueDecl*>();
2139
2140 // Additional restrictions apply in a template argument. We only enforce the
2141 // C++20 restrictions here; additional syntactic and semantic restrictions
2142 // are applied elsewhere.
2143 if (isTemplateArgument(Kind)) {
2144 int InvalidBaseKind = -1;
2145 StringRef Ident;
2146 if (Base.is<TypeInfoLValue>())
2147 InvalidBaseKind = 0;
2148 else if (isa_and_nonnull<StringLiteral>(BaseE))
2149 InvalidBaseKind = 1;
2150 else if (isa_and_nonnull<MaterializeTemporaryExpr>(BaseE) ||
2151 isa_and_nonnull<LifetimeExtendedTemporaryDecl>(BaseVD))
2152 InvalidBaseKind = 2;
2153 else if (auto *PE = dyn_cast_or_null<PredefinedExpr>(BaseE)) {
2154 InvalidBaseKind = 3;
2155 Ident = PE->getIdentKindName();
2156 }
2157
2158 if (InvalidBaseKind != -1) {
2159 Info.FFDiag(Loc, diag::note_constexpr_invalid_template_arg)
2160 << IsReferenceType << !Designator.Entries.empty() << InvalidBaseKind
2161 << Ident;
2162 return false;
2163 }
2164 }
2165
2166 if (auto *FD = dyn_cast_or_null<FunctionDecl>(BaseVD);
2167 FD && FD->isImmediateFunction()) {
2168 Info.FFDiag(Loc, diag::note_consteval_address_accessible)
2169 << !Type->isAnyPointerType();
2170 Info.Note(FD->getLocation(), diag::note_declared_at);
2171 return false;
2172 }
2173
2174 // Check that the object is a global. Note that the fake 'this' object we
2175 // manufacture when checking potential constant expressions is conservatively
2176 // assumed to be global here.
2177 if (!IsGlobalLValue(Base)) {
2178 if (Info.getLangOpts().CPlusPlus11) {
2179 Info.FFDiag(Loc, diag::note_constexpr_non_global, 1)
2180 << IsReferenceType << !Designator.Entries.empty() << !!BaseVD
2181 << BaseVD;
2182 auto *VarD = dyn_cast_or_null<VarDecl>(BaseVD);
2183 if (VarD && VarD->isConstexpr()) {
2184 // Non-static local constexpr variables have unintuitive semantics:
2185 // constexpr int a = 1;
2186 // constexpr const int *p = &a;
2187 // ... is invalid because the address of 'a' is not constant. Suggest
2188 // adding a 'static' in this case.
2189 Info.Note(VarD->getLocation(), diag::note_constexpr_not_static)
2190 << VarD
2191 << FixItHint::CreateInsertion(VarD->getBeginLoc(), "static ");
2192 } else {
2193 NoteLValueLocation(Info, Base);
2194 }
2195 } else {
2196 Info.FFDiag(Loc);
2197 }
2198 // Don't allow references to temporaries to escape.
2199 return false;
2200 }
2201 assert((Info.checkingPotentialConstantExpression() ||
2202 LVal.getLValueCallIndex() == 0) &&
2203 "have call index for global lvalue");
2204
2205 if (Base.is<DynamicAllocLValue>()) {
2206 Info.FFDiag(Loc, diag::note_constexpr_dynamic_alloc)
2207 << IsReferenceType << !Designator.Entries.empty();
2208 NoteLValueLocation(Info, Base);
2209 return false;
2210 }
2211
2212 if (BaseVD) {
2213 if (const VarDecl *Var = dyn_cast<const VarDecl>(BaseVD)) {
2214 // Check if this is a thread-local variable.
2215 if (Var->getTLSKind())
2216 // FIXME: Diagnostic!
2217 return false;
2218
2219 // A dllimport variable never acts like a constant, unless we're
2220 // evaluating a value for use only in name mangling.
2221 if (!isForManglingOnly(Kind) && Var->hasAttr<DLLImportAttr>())
2222 // FIXME: Diagnostic!
2223 return false;
2224
2225 // In CUDA/HIP device compilation, only device side variables have
2226 // constant addresses.
2227 if (Info.getCtx().getLangOpts().CUDA &&
2228 Info.getCtx().getLangOpts().CUDAIsDevice &&
2229 Info.getCtx().CUDAConstantEvalCtx.NoWrongSidedVars) {
2230 if ((!Var->hasAttr<CUDADeviceAttr>() &&
2231 !Var->hasAttr<CUDAConstantAttr>() &&
2232 !Var->getType()->isCUDADeviceBuiltinSurfaceType() &&
2233 !Var->getType()->isCUDADeviceBuiltinTextureType()) ||
2234 Var->hasAttr<HIPManagedAttr>())
2235 return false;
2236 }
2237 }
2238 if (const auto *FD = dyn_cast<const FunctionDecl>(BaseVD)) {
2239 // __declspec(dllimport) must be handled very carefully:
2240 // We must never initialize an expression with the thunk in C++.
2241 // Doing otherwise would allow the same id-expression to yield
2242 // different addresses for the same function in different translation
2243 // units. However, this means that we must dynamically initialize the
2244 // expression with the contents of the import address table at runtime.
2245 //
2246 // The C language has no notion of ODR; furthermore, it has no notion of
2247 // dynamic initialization. This means that we are permitted to
2248 // perform initialization with the address of the thunk.
2249 if (Info.getLangOpts().CPlusPlus && !isForManglingOnly(Kind) &&
2250 FD->hasAttr<DLLImportAttr>())
2251 // FIXME: Diagnostic!
2252 return false;
2253 }
2254 } else if (const auto *MTE =
2255 dyn_cast_or_null<MaterializeTemporaryExpr>(BaseE)) {
2256 if (CheckedTemps.insert(MTE).second) {
2257 QualType TempType = getType(Base);
2258 if (TempType.isDestructedType()) {
2259 Info.FFDiag(MTE->getExprLoc(),
2260 diag::note_constexpr_unsupported_temporary_nontrivial_dtor)
2261 << TempType;
2262 return false;
2263 }
2264
2265 APValue *V = MTE->getOrCreateValue(false);
2266 assert(V && "evasluation result refers to uninitialised temporary");
2267 if (!CheckEvaluationResult(CheckEvaluationResultKind::ConstantExpression,
2268 Info, MTE->getExprLoc(), TempType, *V, Kind,
2269 /*SubobjectDecl=*/nullptr, CheckedTemps))
2270 return false;
2271 }
2272 }
2273
2274 // Allow address constant expressions to be past-the-end pointers. This is
2275 // an extension: the standard requires them to point to an object.
2276 if (!IsReferenceType)
2277 return true;
2278
2279 // A reference constant expression must refer to an object.
2280 if (!Base) {
2281 // FIXME: diagnostic
2282 Info.CCEDiag(Loc);
2283 return true;
2284 }
2285
2286 // Does this refer one past the end of some object?
2287 if (!Designator.Invalid && Designator.isOnePastTheEnd()) {
2288 Info.FFDiag(Loc, diag::note_constexpr_past_end, 1)
2289 << !Designator.Entries.empty() << !!BaseVD << BaseVD;
2290 NoteLValueLocation(Info, Base);
2291 }
2292
2293 return true;
2294}
2295
2296/// Member pointers are constant expressions unless they point to a
2297/// non-virtual dllimport member function.
2298static bool CheckMemberPointerConstantExpression(EvalInfo &Info,
2299 SourceLocation Loc,
2300 QualType Type,
2301 const APValue &Value,
2302 ConstantExprKind Kind) {
2303 const ValueDecl *Member = Value.getMemberPointerDecl();
2304 const auto *FD = dyn_cast_or_null<CXXMethodDecl>(Member);
2305 if (!FD)
2306 return true;
2307 if (FD->isImmediateFunction()) {
2308 Info.FFDiag(Loc, diag::note_consteval_address_accessible) << /*pointer*/ 0;
2309 Info.Note(FD->getLocation(), diag::note_declared_at);
2310 return false;
2311 }
2312 return isForManglingOnly(Kind) || FD->isVirtual() ||
2313 !FD->hasAttr<DLLImportAttr>();
2314}
2315
2316/// Check that this core constant expression is of literal type, and if not,
2317/// produce an appropriate diagnostic.
2318static bool CheckLiteralType(EvalInfo &Info, const Expr *E,
2319 const LValue *This = nullptr) {
2320 if (!E->isPRValue() || E->getType()->isLiteralType(Info.Ctx))
2321 return true;
2322
2323 // C++1y: A constant initializer for an object o [...] may also invoke
2324 // constexpr constructors for o and its subobjects even if those objects
2325 // are of non-literal class types.
2326 //
2327 // C++11 missed this detail for aggregates, so classes like this:
2328 // struct foo_t { union { int i; volatile int j; } u; };
2329 // are not (obviously) initializable like so:
2330 // __attribute__((__require_constant_initialization__))
2331 // static const foo_t x = {{0}};
2332 // because "i" is a subobject with non-literal initialization (due to the
2333 // volatile member of the union). See:
2334 // http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#1677
2335 // Therefore, we use the C++1y behavior.
2336 if (This && Info.EvaluatingDecl == This->getLValueBase())
2337 return true;
2338
2339 // Prvalue constant expressions must be of literal types.
2340 if (Info.getLangOpts().CPlusPlus11)
2341 Info.FFDiag(E, diag::note_constexpr_nonliteral)
2342 << E->getType();
2343 else
2344 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
2345 return false;
2346}
2347
2349 EvalInfo &Info, SourceLocation DiagLoc,
2350 QualType Type, const APValue &Value,
2351 ConstantExprKind Kind,
2352 const FieldDecl *SubobjectDecl,
2353 CheckedTemporaries &CheckedTemps) {
2354 if (!Value.hasValue()) {
2355 assert(SubobjectDecl && "SubobjectDecl shall be non-null");
2356 Info.FFDiag(DiagLoc, diag::note_constexpr_uninitialized) << SubobjectDecl;
2357 Info.Note(SubobjectDecl->getLocation(),
2358 diag::note_constexpr_subobject_declared_here);
2359 return false;
2360 }
2361
2362 // We allow _Atomic(T) to be initialized from anything that T can be
2363 // initialized from.
2364 if (const AtomicType *AT = Type->getAs<AtomicType>())
2365 Type = AT->getValueType();
2366
2367 // Core issue 1454: For a literal constant expression of array or class type,
2368 // each subobject of its value shall have been initialized by a constant
2369 // expression.
2370 if (Value.isArray()) {
2372 for (unsigned I = 0, N = Value.getArrayInitializedElts(); I != N; ++I) {
2373 if (!CheckEvaluationResult(CERK, Info, DiagLoc, EltTy,
2374 Value.getArrayInitializedElt(I), Kind,
2375 SubobjectDecl, CheckedTemps))
2376 return false;
2377 }
2378 if (!Value.hasArrayFiller())
2379 return true;
2380 return CheckEvaluationResult(CERK, Info, DiagLoc, EltTy,
2381 Value.getArrayFiller(), Kind, SubobjectDecl,
2382 CheckedTemps);
2383 }
2384 if (Value.isUnion() && Value.getUnionField()) {
2385 return CheckEvaluationResult(
2386 CERK, Info, DiagLoc, Value.getUnionField()->getType(),
2387 Value.getUnionValue(), Kind, Value.getUnionField(), CheckedTemps);
2388 }
2389 if (Value.isStruct()) {
2390 RecordDecl *RD = Type->castAs<RecordType>()->getDecl();
2391 if (const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(RD)) {
2392 unsigned BaseIndex = 0;
2393 for (const CXXBaseSpecifier &BS : CD->bases()) {
2394 if (!CheckEvaluationResult(CERK, Info, DiagLoc, BS.getType(),
2395 Value.getStructBase(BaseIndex), Kind,
2396 /*SubobjectDecl=*/nullptr, CheckedTemps))
2397 return false;
2398 ++BaseIndex;
2399 }
2400 }
2401 for (const auto *I : RD->fields()) {
2402 if (I->isUnnamedBitfield())
2403 continue;
2404
2405 if (!CheckEvaluationResult(CERK, Info, DiagLoc, I->getType(),
2406 Value.getStructField(I->getFieldIndex()), Kind,
2407 I, CheckedTemps))
2408 return false;
2409 }
2410 }
2411
2412 if (Value.isLValue() &&
2413 CERK == CheckEvaluationResultKind::ConstantExpression) {
2414 LValue LVal;
2415 LVal.setFrom(Info.Ctx, Value);
2416 return CheckLValueConstantExpression(Info, DiagLoc, Type, LVal, Kind,
2417 CheckedTemps);
2418 }
2419
2420 if (Value.isMemberPointer() &&
2421 CERK == CheckEvaluationResultKind::ConstantExpression)
2422 return CheckMemberPointerConstantExpression(Info, DiagLoc, Type, Value, Kind);
2423
2424 // Everything else is fine.
2425 return true;
2426}
2427
2428/// Check that this core constant expression value is a valid value for a
2429/// constant expression. If not, report an appropriate diagnostic. Does not
2430/// check that the expression is of literal type.
2431static bool CheckConstantExpression(EvalInfo &Info, SourceLocation DiagLoc,
2432 QualType Type, const APValue &Value,
2433 ConstantExprKind Kind) {
2434 // Nothing to check for a constant expression of type 'cv void'.
2435 if (Type->isVoidType())
2436 return true;
2437
2438 CheckedTemporaries CheckedTemps;
2439 return CheckEvaluationResult(CheckEvaluationResultKind::ConstantExpression,
2440 Info, DiagLoc, Type, Value, Kind,
2441 /*SubobjectDecl=*/nullptr, CheckedTemps);
2442}
2443
2444/// Check that this evaluated value is fully-initialized and can be loaded by
2445/// an lvalue-to-rvalue conversion.
2446static bool CheckFullyInitialized(EvalInfo &Info, SourceLocation DiagLoc,
2447 QualType Type, const APValue &Value) {
2448 CheckedTemporaries CheckedTemps;
2449 return CheckEvaluationResult(
2450 CheckEvaluationResultKind::FullyInitialized, Info, DiagLoc, Type, Value,
2451 ConstantExprKind::Normal, /*SubobjectDecl=*/nullptr, CheckedTemps);
2452}
2453
2454/// Enforce C++2a [expr.const]/4.17, which disallows new-expressions unless
2455/// "the allocated storage is deallocated within the evaluation".
2456static bool CheckMemoryLeaks(EvalInfo &Info) {
2457 if (!Info.HeapAllocs.empty()) {
2458 // We can still fold to a constant despite a compile-time memory leak,
2459 // so long as the heap allocation isn't referenced in the result (we check
2460 // that in CheckConstantExpression).
2461 Info.CCEDiag(Info.HeapAllocs.begin()->second.AllocExpr,
2462 diag::note_constexpr_memory_leak)
2463 << unsigned(Info.HeapAllocs.size() - 1);
2464 }
2465 return true;
2466}
2467
2468static bool EvalPointerValueAsBool(const APValue &Value, bool &Result) {
2469 // A null base expression indicates a null pointer. These are always
2470 // evaluatable, and they are false unless the offset is zero.
2471 if (!Value.getLValueBase()) {
2472 // TODO: Should a non-null pointer with an offset of zero evaluate to true?
2473 Result = !Value.getLValueOffset().isZero();
2474 return true;
2475 }
2476
2477 // We have a non-null base. These are generally known to be true, but if it's
2478 // a weak declaration it can be null at runtime.
2479 Result = true;
2480 const ValueDecl *Decl = Value.getLValueBase().dyn_cast<const ValueDecl*>();
2481 return !Decl || !Decl->isWeak();
2482}
2483
2484static bool HandleConversionToBool(const APValue &Val, bool &Result) {
2485 // TODO: This function should produce notes if it fails.
2486 switch (Val.getKind()) {
2487 case APValue::None:
2489 return false;
2490 case APValue::Int:
2491 Result = Val.getInt().getBoolValue();
2492 return true;
2494 Result = Val.getFixedPoint().getBoolValue();
2495 return true;
2496 case APValue::Float:
2497 Result = !Val.getFloat().isZero();
2498 return true;
2500 Result = Val.getComplexIntReal().getBoolValue() ||
2501 Val.getComplexIntImag().getBoolValue();
2502 return true;
2504 Result = !Val.getComplexFloatReal().isZero() ||
2505 !Val.getComplexFloatImag().isZero();
2506 return true;
2507 case APValue::LValue:
2508 return EvalPointerValueAsBool(Val, Result);
2510 if (Val.getMemberPointerDecl() && Val.getMemberPointerDecl()->isWeak()) {
2511 return false;
2512 }
2513 Result = Val.getMemberPointerDecl();
2514 return true;
2515 case APValue::Vector:
2516 case APValue::Array:
2517 case APValue::Struct:
2518 case APValue::Union:
2520 return false;
2521 }
2522
2523 llvm_unreachable("unknown APValue kind");
2524}
2525
2526static bool EvaluateAsBooleanCondition(const Expr *E, bool &Result,
2527 EvalInfo &Info) {
2528 assert(!E->isValueDependent());
2529 assert(E->isPRValue() && "missing lvalue-to-rvalue conv in bool condition");
2530 APValue Val;
2531 if (!Evaluate(Val, Info, E))
2532 return false;
2533 return HandleConversionToBool(Val, Result);
2534}
2535
2536template<typename T>
2537static bool HandleOverflow(EvalInfo &Info, const Expr *E,
2538 const T &SrcValue, QualType DestType) {
2539 Info.CCEDiag(E, diag::note_constexpr_overflow)
2540 << SrcValue << DestType;
2541 return Info.noteUndefinedBehavior();
2542}
2543
2544static bool HandleFloatToIntCast(EvalInfo &Info, const Expr *E,
2545 QualType SrcType, const APFloat &Value,
2546 QualType DestType, APSInt &Result) {
2547 unsigned DestWidth = Info.Ctx.getIntWidth(DestType);
2548 // Determine whether we are converting to unsigned or signed.
2549 bool DestSigned = DestType->isSignedIntegerOrEnumerationType();
2550
2551 Result = APSInt(DestWidth, !DestSigned);
2552 bool ignored;
2553 if (Value.convertToInteger(Result, llvm::APFloat::rmTowardZero, &ignored)
2554 & APFloat::opInvalidOp)
2555 return HandleOverflow(Info, E, Value, DestType);
2556 return true;
2557}
2558
2559/// Get rounding mode to use in evaluation of the specified expression.
2560///
2561/// If rounding mode is unknown at compile time, still try to evaluate the
2562/// expression. If the result is exact, it does not depend on rounding mode.
2563/// So return "tonearest" mode instead of "dynamic".
2564static llvm::RoundingMode getActiveRoundingMode(EvalInfo &Info, const Expr *E) {
2565 llvm::RoundingMode RM =
2566 E->getFPFeaturesInEffect(Info.Ctx.getLangOpts()).getRoundingMode();
2567 if (RM == llvm::RoundingMode::Dynamic)
2568 RM = llvm::RoundingMode::NearestTiesToEven;
2569 return RM;
2570}
2571
2572/// Check if the given evaluation result is allowed for constant evaluation.
2573static bool checkFloatingPointResult(EvalInfo &Info, const Expr *E,
2574 APFloat::opStatus St) {
2575 // In a constant context, assume that any dynamic rounding mode or FP
2576 // exception state matches the default floating-point environment.
2577 if (Info.InConstantContext)
2578 return true;
2579
2580 FPOptions FPO = E->getFPFeaturesInEffect(Info.Ctx.getLangOpts());
2581 if ((St & APFloat::opInexact) &&
2582 FPO.getRoundingMode() == llvm::RoundingMode::Dynamic) {
2583 // Inexact result means that it depends on rounding mode. If the requested
2584 // mode is dynamic, the evaluation cannot be made in compile time.
2585 Info.FFDiag(E, diag::note_constexpr_dynamic_rounding);
2586 return false;
2587 }
2588
2589 if ((St != APFloat::opOK) &&
2590 (FPO.getRoundingMode() == llvm::RoundingMode::Dynamic ||
2592 FPO.getAllowFEnvAccess())) {
2593 Info.FFDiag(E, diag::note_constexpr_float_arithmetic_strict);
2594 return false;
2595 }
2596
2597 if ((St & APFloat::opStatus::opInvalidOp) &&
2599 // There is no usefully definable result.
2600 Info.FFDiag(E);
2601 return false;
2602 }
2603
2604 // FIXME: if:
2605 // - evaluation triggered other FP exception, and
2606 // - exception mode is not "ignore", and
2607 // - the expression being evaluated is not a part of global variable
2608 // initializer,
2609 // the evaluation probably need to be rejected.
2610 return true;
2611}
2612
2613static bool HandleFloatToFloatCast(EvalInfo &Info, const Expr *E,
2614 QualType SrcType, QualType DestType,
2615 APFloat &Result) {
2616 assert(isa<CastExpr>(E) || isa<CompoundAssignOperator>(E));
2617 llvm::RoundingMode RM = getActiveRoundingMode(Info, E);
2618 APFloat::opStatus St;
2619 APFloat Value = Result;
2620 bool ignored;
2621 St = Result.convert(Info.Ctx.getFloatTypeSemantics(DestType), RM, &ignored);
2622 return checkFloatingPointResult(Info, E, St);
2623}
2624
2625static APSInt HandleIntToIntCast(EvalInfo &Info, const Expr *E,
2626 QualType DestType, QualType SrcType,
2627 const APSInt &Value) {
2628 unsigned DestWidth = Info.Ctx.getIntWidth(DestType);
2629 // Figure out if this is a truncate, extend or noop cast.
2630 // If the input is signed, do a sign extend, noop, or truncate.
2631 APSInt Result = Value.extOrTrunc(DestWidth);
2632 Result.setIsUnsigned(DestType->isUnsignedIntegerOrEnumerationType());
2633 if (DestType->isBooleanType())
2634 Result = Value.getBoolValue();
2635 return Result;
2636}
2637
2638static bool HandleIntToFloatCast(EvalInfo &Info, const Expr *E,
2639 const FPOptions FPO,
2640 QualType SrcType, const APSInt &Value,
2641 QualType DestType, APFloat &Result) {
2642 Result = APFloat(Info.Ctx.getFloatTypeSemantics(DestType), 1);
2643 llvm::RoundingMode RM = getActiveRoundingMode(Info, E);
2644 APFloat::opStatus St = Result.convertFromAPInt(Value, Value.isSigned(), RM);
2645 return checkFloatingPointResult(Info, E, St);
2646}
2647
2648static bool truncateBitfieldValue(EvalInfo &Info, const Expr *E,
2649 APValue &Value, const FieldDecl *FD) {
2650 assert(FD->isBitField() && "truncateBitfieldValue on non-bitfield");
2651
2652 if (!Value.isInt()) {
2653 // Trying to store a pointer-cast-to-integer into a bitfield.
2654 // FIXME: In this case, we should provide the diagnostic for casting
2655 // a pointer to an integer.
2656 assert(Value.isLValue() && "integral value neither int nor lvalue?");
2657 Info.FFDiag(E);
2658 return false;
2659 }
2660
2661 APSInt &Int = Value.getInt();
2662 unsigned OldBitWidth = Int.getBitWidth();
2663 unsigned NewBitWidth = FD->getBitWidthValue(Info.Ctx);
2664 if (NewBitWidth < OldBitWidth)
2665 Int = Int.trunc(NewBitWidth).extend(OldBitWidth);
2666 return true;
2667}
2668
2669static bool EvalAndBitcastToAPInt(EvalInfo &Info, const Expr *E,
2670 llvm::APInt &Res) {
2671 APValue SVal;
2672 if (!Evaluate(SVal, Info, E))
2673 return false;
2674 if (SVal.isInt()) {
2675 Res = SVal.getInt();
2676 return true;
2677 }
2678 if (SVal.isFloat()) {
2679 Res = SVal.getFloat().bitcastToAPInt();
2680 return true;
2681 }
2682 if (SVal.isVector()) {
2683 QualType VecTy = E->getType();
2684 unsigned VecSize = Info.Ctx.getTypeSize(VecTy);
2685 QualType EltTy = VecTy->castAs<VectorType>()->getElementType();
2686 unsigned EltSize = Info.Ctx.getTypeSize(EltTy);
2687 bool BigEndian = Info.Ctx.getTargetInfo().isBigEndian();
2688 Res = llvm::APInt::getZero(VecSize);
2689 for (unsigned i = 0; i < SVal.getVectorLength(); i++) {
2690 APValue &Elt = SVal.getVectorElt(i);
2691 llvm::APInt EltAsInt;
2692 if (Elt.isInt()) {
2693 EltAsInt = Elt.getInt();
2694 } else if (Elt.isFloat()) {
2695 EltAsInt = Elt.getFloat().bitcastToAPInt();
2696 } else {
2697 // Don't try to handle vectors of anything other than int or float
2698 // (not sure if it's possible to hit this case).
2699 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
2700 return false;
2701 }
2702 unsigned BaseEltSize = EltAsInt.getBitWidth();
2703 if (BigEndian)
2704 Res |= EltAsInt.zextOrTrunc(VecSize).rotr(i*EltSize+BaseEltSize);
2705 else
2706 Res |= EltAsInt.zextOrTrunc(VecSize).rotl(i*EltSize);
2707 }
2708 return true;
2709 }
2710 // Give up if the input isn't an int, float, or vector. For example, we
2711 // reject "(v4i16)(intptr_t)&a".
2712 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
2713 return false;
2714}
2715
2716/// Perform the given integer operation, which is known to need at most BitWidth
2717/// bits, and check for overflow in the original type (if that type was not an
2718/// unsigned type).
2719template<typename Operation>
2720static bool CheckedIntArithmetic(EvalInfo &Info, const Expr *E,
2721 const APSInt &LHS, const APSInt &RHS,
2722 unsigned BitWidth, Operation Op,
2723 APSInt &Result) {
2724 if (LHS.isUnsigned()) {
2725 Result = Op(LHS, RHS);
2726 return true;
2727 }
2728
2729 APSInt Value(Op(LHS.extend(BitWidth), RHS.extend(BitWidth)), false);
2730 Result = Value.trunc(LHS.getBitWidth());
2731 if (Result.extend(BitWidth) != Value) {
2732 if (Info.checkingForUndefinedBehavior())
2733 Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
2734 diag::warn_integer_constant_overflow)
2735 << toString(Result, 10) << E->getType();
2736 return HandleOverflow(Info, E, Value, E->getType());
2737 }
2738 return true;
2739}
2740
2741/// Perform the given binary integer operation.
2742static bool handleIntIntBinOp(EvalInfo &Info, const Expr *E, const APSInt &LHS,
2743 BinaryOperatorKind Opcode, APSInt RHS,
2744 APSInt &Result) {
2745 bool HandleOverflowResult = true;
2746 switch (Opcode) {
2747 default:
2748 Info.FFDiag(E);
2749 return false;
2750 case BO_Mul:
2751 return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() * 2,
2752 std::multiplies<APSInt>(), Result);
2753 case BO_Add:
2754 return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1,
2755 std::plus<APSInt>(), Result);
2756 case BO_Sub:
2757 return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1,
2758 std::minus<APSInt>(), Result);
2759 case BO_And: Result = LHS & RHS; return true;
2760 case BO_Xor: Result = LHS ^ RHS; return true;
2761 case BO_Or: Result = LHS | RHS; return true;
2762 case BO_Div:
2763 case BO_Rem:
2764 if (RHS == 0) {
2765 Info.FFDiag(E, diag::note_expr_divide_by_zero);
2766 return false;
2767 }
2768 // Check for overflow case: INT_MIN / -1 or INT_MIN % -1. APSInt supports
2769 // this operation and gives the two's complement result.
2770 if (RHS.isNegative() && RHS.isAllOnes() && LHS.isSigned() &&
2771 LHS.isMinSignedValue())
2772 HandleOverflowResult = HandleOverflow(
2773 Info, E, -LHS.extend(LHS.getBitWidth() + 1), E->getType());
2774 Result = (Opcode == BO_Rem ? LHS % RHS : LHS / RHS);
2775 return HandleOverflowResult;
2776 case BO_Shl: {
2777 if (Info.getLangOpts().OpenCL)
2778 // OpenCL 6.3j: shift values are effectively % word size of LHS.
2779 RHS &= APSInt(llvm::APInt(RHS.getBitWidth(),
2780 static_cast<uint64_t>(LHS.getBitWidth() - 1)),
2781 RHS.isUnsigned());
2782 else if (RHS.isSigned() && RHS.isNegative()) {
2783 // During constant-folding, a negative shift is an opposite shift. Such
2784 // a shift is not a constant expression.
2785 Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHS;
2786 RHS = -RHS;
2787 goto shift_right;
2788 }
2789 shift_left:
2790 // C++11 [expr.shift]p1: Shift width must be less than the bit width of
2791 // the shifted type.
2792 unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1);
2793 if (SA != RHS) {
2794 Info.CCEDiag(E, diag::note_constexpr_large_shift)
2795 << RHS << E->getType() << LHS.getBitWidth();
2796 } else if (LHS.isSigned() && !Info.getLangOpts().CPlusPlus20) {
2797 // C++11 [expr.shift]p2: A signed left shift must have a non-negative
2798 // operand, and must not overflow the corresponding unsigned type.
2799 // C++2a [expr.shift]p2: E1 << E2 is the unique value congruent to
2800 // E1 x 2^E2 module 2^N.
2801 if (LHS.isNegative())
2802 Info.CCEDiag(E, diag::note_constexpr_lshift_of_negative) << LHS;
2803 else if (LHS.countl_zero() < SA)
2804 Info.CCEDiag(E, diag::note_constexpr_lshift_discards);
2805 }
2806 Result = LHS << SA;
2807 return true;
2808 }
2809 case BO_Shr: {
2810 if (Info.getLangOpts().OpenCL)
2811 // OpenCL 6.3j: shift values are effectively % word size of LHS.
2812 RHS &= APSInt(llvm::APInt(RHS.getBitWidth(),
2813 static_cast<uint64_t>(LHS.getBitWidth() - 1)),
2814 RHS.isUnsigned());
2815 else if (RHS.isSigned() && RHS.isNegative()) {
2816 // During constant-folding, a negative shift is an opposite shift. Such a
2817 // shift is not a constant expression.
2818 Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHS;
2819 RHS = -RHS;
2820 goto shift_left;
2821 }
2822 shift_right:
2823 // C++11 [expr.shift]p1: Shift width must be less than the bit width of the
2824 // shifted type.
2825 unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1);
2826 if (SA != RHS)
2827 Info.CCEDiag(E, diag::note_constexpr_large_shift)
2828 << RHS << E->getType() << LHS.getBitWidth();
2829 Result = LHS >> SA;
2830 return true;
2831 }
2832
2833 case BO_LT: Result = LHS < RHS; return true;
2834 case BO_GT: Result = LHS > RHS; return true;
2835 case BO_LE: Result = LHS <= RHS; return true;
2836 case BO_GE: Result = LHS >= RHS; return true;
2837 case BO_EQ: Result = LHS == RHS; return true;
2838 case BO_NE: Result = LHS != RHS; return true;
2839 case BO_Cmp:
2840 llvm_unreachable("BO_Cmp should be handled elsewhere");
2841 }
2842}
2843
2844/// Perform the given binary floating-point operation, in-place, on LHS.
2845static bool handleFloatFloatBinOp(EvalInfo &Info, const BinaryOperator *E,
2846 APFloat &LHS, BinaryOperatorKind Opcode,
2847 const APFloat &RHS) {
2848 llvm::RoundingMode RM = getActiveRoundingMode(Info, E);
2849 APFloat::opStatus St;
2850 switch (Opcode) {
2851 default:
2852 Info.FFDiag(E);
2853 return false;
2854 case BO_Mul:
2855 St = LHS.multiply(RHS, RM);
2856 break;
2857 case BO_Add:
2858 St = LHS.add(RHS, RM);
2859 break;
2860 case BO_Sub:
2861 St = LHS.subtract(RHS, RM);
2862 break;
2863 case BO_Div:
2864 // [expr.mul]p4:
2865 // If the second operand of / or % is zero the behavior is undefined.
2866 if (RHS.isZero())
2867 Info.CCEDiag(E, diag::note_expr_divide_by_zero);
2868 St = LHS.divide(RHS, RM);
2869 break;
2870 }
2871
2872 // [expr.pre]p4:
2873 // If during the evaluation of an expression, the result is not
2874 // mathematically defined [...], the behavior is undefined.
2875 // FIXME: C++ rules require us to not conform to IEEE 754 here.
2876 if (LHS.isNaN()) {
2877 Info.CCEDiag(E, diag::note_constexpr_float_arithmetic) << LHS.isNaN();
2878 return Info.noteUndefinedBehavior();
2879 }
2880
2881 return checkFloatingPointResult(Info, E, St);
2882}
2883
2884static bool handleLogicalOpForVector(const APInt &LHSValue,
2885 BinaryOperatorKind Opcode,
2886 const APInt &RHSValue, APInt &Result) {
2887 bool LHS = (LHSValue != 0);
2888 bool RHS = (RHSValue != 0);
2889
2890 if (Opcode == BO_LAnd)
2891 Result = LHS && RHS;
2892 else
2893 Result = LHS || RHS;
2894 return true;
2895}
2896static bool handleLogicalOpForVector(const APFloat &LHSValue,
2897 BinaryOperatorKind Opcode,
2898 const APFloat &RHSValue, APInt &Result) {
2899 bool LHS = !LHSValue.isZero();
2900 bool RHS = !RHSValue.isZero();
2901
2902 if (Opcode == BO_LAnd)
2903 Result = LHS && RHS;
2904 else
2905 Result = LHS || RHS;
2906 return true;
2907}
2908
2909static bool handleLogicalOpForVector(const APValue &LHSValue,
2910 BinaryOperatorKind Opcode,
2911 const APValue &RHSValue, APInt &Result) {
2912 // The result is always an int type, however operands match the first.
2913 if (LHSValue.getKind() == APValue::Int)
2914 return handleLogicalOpForVector(LHSValue.getInt(), Opcode,
2915 RHSValue.getInt(), Result);
2916 assert(LHSValue.getKind() == APValue::Float && "Should be no other options");
2917 return handleLogicalOpForVector(LHSValue.getFloat(), Opcode,
2918 RHSValue.getFloat(), Result);
2919}
2920
2921template <typename APTy>
2922static bool
2924 const APTy &RHSValue, APInt &Result) {
2925 switch (Opcode) {
2926 default:
2927 llvm_unreachable("unsupported binary operator");
2928 case BO_EQ:
2929 Result = (LHSValue == RHSValue);
2930 break;
2931 case BO_NE:
2932 Result = (LHSValue != RHSValue);
2933 break;
2934 case BO_LT:
2935 Result = (LHSValue < RHSValue);
2936 break;
2937 case BO_GT:
2938 Result = (LHSValue > RHSValue);
2939 break;
2940 case BO_LE:
2941 Result = (LHSValue <= RHSValue);
2942 break;
2943 case BO_GE:
2944 Result = (LHSValue >= RHSValue);
2945 break;
2946 }
2947
2948 // The boolean operations on these vector types use an instruction that
2949 // results in a mask of '-1' for the 'truth' value. Ensure that we negate 1
2950 // to -1 to make sure that we produce the correct value.
2951 Result.negate();
2952
2953 return true;
2954}
2955
2956static bool handleCompareOpForVector(const APValue &LHSValue,
2957 BinaryOperatorKind Opcode,
2958 const APValue &RHSValue, APInt &Result) {
2959 // The result is always an int type, however operands match the first.
2960 if (LHSValue.getKind() == APValue::Int)
2961 return handleCompareOpForVectorHelper(LHSValue.getInt(), Opcode,
2962 RHSValue.getInt(), Result);
2963 assert(LHSValue.getKind() == APValue::Float && "Should be no other options");
2964 return handleCompareOpForVectorHelper(LHSValue.getFloat(), Opcode,
2965 RHSValue.getFloat(), Result);
2966}
2967
2968// Perform binary operations for vector types, in place on the LHS.
2969static bool handleVectorVectorBinOp(EvalInfo &Info, const BinaryOperator *E,
2970 BinaryOperatorKind Opcode,
2971 APValue &LHSValue,
2972 const APValue &RHSValue) {
2973 assert(Opcode != BO_PtrMemD && Opcode != BO_PtrMemI &&
2974 "Operation not supported on vector types");
2975
2976 const auto *VT = E->getType()->castAs<VectorType>();
2977 unsigned NumElements = VT->getNumElements();
2978 QualType EltTy = VT->getElementType();
2979
2980 // In the cases (typically C as I've observed) where we aren't evaluating
2981 // constexpr but are checking for cases where the LHS isn't yet evaluatable,
2982 // just give up.
2983 if (!LHSValue.isVector()) {
2984 assert(LHSValue.isLValue() &&
2985 "A vector result that isn't a vector OR uncalculated LValue");
2986 Info.FFDiag(E);
2987 return false;
2988 }
2989
2990 assert(LHSValue.getVectorLength() == NumElements &&
2991 RHSValue.getVectorLength() == NumElements && "Different vector sizes");
2992
2993 SmallVector<APValue, 4> ResultElements;
2994
2995 for (unsigned EltNum = 0; EltNum < NumElements; ++EltNum) {
2996 APValue LHSElt = LHSValue.getVectorElt(EltNum);
2997 APValue RHSElt = RHSValue.getVectorElt(EltNum);
2998
2999 if (EltTy->isIntegerType()) {
3000 APSInt EltResult{Info.Ctx.getIntWidth(EltTy),
3001 EltTy->isUnsignedIntegerType()};
3002 bool Success = true;
3003
3004 if (BinaryOperator::isLogicalOp(Opcode))
3005 Success = handleLogicalOpForVector(LHSElt, Opcode, RHSElt, EltResult);
3006 else if (BinaryOperator::isComparisonOp(Opcode))
3007 Success = handleCompareOpForVector(LHSElt, Opcode, RHSElt, EltResult);
3008 else
3009 Success = handleIntIntBinOp(Info, E, LHSElt.getInt(), Opcode,
3010 RHSElt.getInt(), EltResult);
3011
3012 if (!Success) {
3013 Info.FFDiag(E);
3014 return false;
3015 }
3016 ResultElements.emplace_back(EltResult);
3017
3018 } else if (EltTy->isFloatingType()) {
3019 assert(LHSElt.getKind() == APValue::Float &&
3020 RHSElt.getKind() == APValue::Float &&
3021 "Mismatched LHS/RHS/Result Type");
3022 APFloat LHSFloat = LHSElt.getFloat();
3023
3024 if (!handleFloatFloatBinOp(Info, E, LHSFloat, Opcode,
3025 RHSElt.getFloat())) {
3026 Info.FFDiag(E);
3027 return false;
3028 }
3029
3030 ResultElements.emplace_back(LHSFloat);
3031 }
3032 }
3033
3034 LHSValue = APValue(ResultElements.data(), ResultElements.size());
3035 return true;
3036}
3037
3038/// Cast an lvalue referring to a base subobject to a derived class, by
3039/// truncating the lvalue's path to the given length.
3040static bool CastToDerivedClass(EvalInfo &Info, const Expr *E, LValue &Result,
3041 const RecordDecl *TruncatedType,
3042 unsigned TruncatedElements) {
3043 SubobjectDesignator &D = Result.Designator;
3044
3045 // Check we actually point to a derived class object.
3046 if (TruncatedElements == D.Entries.size())
3047 return true;
3048 assert(TruncatedElements >= D.MostDerivedPathLength &&
3049 "not casting to a derived class");
3050 if (!Result.checkSubobject(Info, E, CSK_Derived))
3051 return false;
3052
3053 // Truncate the path to the subobject, and remove any derived-to-base offsets.
3054 const RecordDecl *RD = TruncatedType;
3055 for (unsigned I = TruncatedElements, N = D.Entries.size(); I != N; ++I) {
3056 if (RD->isInvalidDecl()) return false;
3057 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
3058 const CXXRecordDecl *Base = getAsBaseClass(D.Entries[I]);
3059 if (isVirtualBaseClass(D.Entries[I]))
3060 Result.Offset -= Layout.getVBaseClassOffset(Base);
3061 else
3062 Result.Offset -= Layout.getBaseClassOffset(Base);
3063 RD = Base;
3064 }
3065 D.Entries.resize(TruncatedElements);
3066 return true;
3067}
3068
3069static bool HandleLValueDirectBase(EvalInfo &Info, const Expr *E, LValue &Obj,
3070 const CXXRecordDecl *Derived,
3071 const CXXRecordDecl *Base,
3072 const ASTRecordLayout *RL = nullptr) {
3073 if (!RL) {
3074 if (Derived->isInvalidDecl()) return false;
3075 RL = &Info.Ctx.getASTRecordLayout(Derived);
3076 }
3077
3078 Obj.getLValueOffset() += RL->getBaseClassOffset(Base);
3079 Obj.addDecl(Info, E, Base, /*Virtual*/ false);
3080 return true;
3081}
3082
3083static bool HandleLValueBase(EvalInfo &Info, const Expr *E, LValue &Obj,
3084 const CXXRecordDecl *DerivedDecl,
3085 const CXXBaseSpecifier *Base) {
3086 const CXXRecordDecl *BaseDecl = Base->getType()->getAsCXXRecordDecl();
3087
3088 if (!Base->isVirtual())
3089 return HandleLValueDirectBase(Info, E, Obj, DerivedDecl, BaseDecl);
3090
3091 SubobjectDesignator &D = Obj.Designator;
3092 if (D.Invalid)
3093 return false;
3094
3095 // Extract most-derived object and corresponding type.
3096 DerivedDecl = D.MostDerivedType->getAsCXXRecordDecl();
3097 if (!CastToDerivedClass(Info, E, Obj, DerivedDecl, D.MostDerivedPathLength))
3098 return false;
3099
3100 // Find the virtual base class.
3101 if (DerivedDecl->isInvalidDecl()) return false;
3102 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(DerivedDecl);
3103 Obj.getLValueOffset() += Layout.getVBaseClassOffset(BaseDecl);
3104 Obj.addDecl(Info, E, BaseDecl, /*Virtual*/ true);
3105 return true;
3106}
3107
3108static bool HandleLValueBasePath(EvalInfo &Info, const CastExpr *E,
3109 QualType Type, LValue &Result) {
3110 for (CastExpr::path_const_iterator PathI = E->path_begin(),
3111 PathE = E->path_end();
3112 PathI != PathE; ++PathI) {
3113 if (!HandleLValueBase(Info, E, Result, Type->getAsCXXRecordDecl(),
3114 *PathI))
3115 return false;
3116 Type = (*PathI)->getType();
3117 }
3118 return true;
3119}
3120
3121/// Cast an lvalue referring to a derived class to a known base subobject.
3122static bool CastToBaseClass(EvalInfo &Info, const Expr *E, LValue &Result,
3123 const CXXRecordDecl *DerivedRD,
3124 const CXXRecordDecl *BaseRD) {
3125 CXXBasePaths Paths(/*FindAmbiguities=*/false,
3126 /*RecordPaths=*/true, /*DetectVirtual=*/false);
3127 if (!DerivedRD->isDerivedFrom(BaseRD, Paths))
3128 llvm_unreachable("Class must be derived from the passed in base class!");
3129
3130 for (CXXBasePathElement &Elem : Paths.front())
3131 if (!HandleLValueBase(Info, E, Result, Elem.Class, Elem.Base))
3132 return false;
3133 return true;
3134}
3135
3136/// Update LVal to refer to the given field, which must be a member of the type
3137/// currently described by LVal.
3138static bool HandleLValueMember(EvalInfo &Info, const Expr *E, LValue &LVal,
3139 const FieldDecl *FD,
3140 const ASTRecordLayout *RL = nullptr) {
3141 if (!RL) {
3142 if (FD->getParent()->isInvalidDecl()) return false;
3143 RL = &Info.Ctx.getASTRecordLayout(FD->getParent());
3144 }
3145
3146 unsigned I = FD->getFieldIndex();
3147 LVal.adjustOffset(Info.Ctx.toCharUnitsFromBits(RL->getFieldOffset(I)));
3148 LVal.addDecl(Info, E, FD);
3149 return true;
3150}
3151
3152/// Update LVal to refer to the given indirect field.
3153static bool HandleLValueIndirectMember(EvalInfo &Info, const Expr *E,
3154 LValue &LVal,
3155 const IndirectFieldDecl *IFD) {
3156 for (const auto *C : IFD->chain())
3157 if (!HandleLValueMember(Info, E, LVal, cast<FieldDecl>(C)))
3158 return false;
3159 return true;
3160}
3161
3162/// Get the size of the given type in char units.
3163static bool HandleSizeof(EvalInfo &Info, SourceLocation Loc,
3164 QualType Type, CharUnits &Size) {
3165 // sizeof(void), __alignof__(void), sizeof(function) = 1 as a gcc
3166 // extension.
3167 if (Type->isVoidType() || Type->isFunctionType()) {
3168 Size = CharUnits::One();
3169 return true;
3170 }
3171
3172 if (Type->isDependentType()) {
3173 Info.FFDiag(Loc);
3174 return false;
3175 }
3176
3177 if (!Type->isConstantSizeType()) {
3178 // sizeof(vla) is not a constantexpr: C99 6.5.3.4p2.
3179 // FIXME: Better diagnostic.
3180 Info.FFDiag(Loc);
3181 return false;
3182 }
3183
3184 Size = Info.Ctx.getTypeSizeInChars(Type);
3185 return true;
3186}
3187
3188/// Update a pointer value to model pointer arithmetic.
3189/// \param Info - Information about the ongoing evaluation.
3190/// \param E - The expression being evaluated, for diagnostic purposes.
3191/// \param LVal - The pointer value to be updated.
3192/// \param EltTy - The pointee type represented by LVal.
3193/// \param Adjustment - The adjustment, in objects of type EltTy, to add.
3194static bool HandleLValueArrayAdjustment(EvalInfo &Info, const Expr *E,
3195 LValue &LVal, QualType EltTy,
3196 APSInt Adjustment) {
3197 CharUnits SizeOfPointee;
3198 if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfPointee))
3199 return false;
3200
3201 LVal.adjustOffsetAndIndex(Info, E, Adjustment, SizeOfPointee);
3202 return true;
3203}
3204
3205static bool HandleLValueArrayAdjustment(EvalInfo &Info, const Expr *E,
3206 LValue &LVal, QualType EltTy,
3207 int64_t Adjustment) {
3208 return HandleLValueArrayAdjustment(Info, E, LVal, EltTy,
3209 APSInt::get(Adjustment));
3210}
3211
3212/// Update an lvalue to refer to a component of a complex number.
3213/// \param Info - Information about the ongoing evaluation.
3214/// \param LVal - The lvalue to be updated.
3215/// \param EltTy - The complex number's component type.
3216/// \param Imag - False for the real component, true for the imaginary.
3217static bool HandleLValueComplexElement(EvalInfo &Info, const Expr *E,
3218 LValue &LVal, QualType EltTy,
3219 bool Imag) {
3220 if (Imag) {
3221 CharUnits SizeOfComponent;
3222 if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfComponent))
3223 return false;
3224 LVal.Offset += SizeOfComponent;
3225 }
3226 LVal.addComplex(Info, E, EltTy, Imag);
3227 return true;
3228}
3229
3230/// Try to evaluate the initializer for a variable declaration.
3231///
3232/// \param Info Information about the ongoing evaluation.
3233/// \param E An expression to be used when printing diagnostics.
3234/// \param VD The variable whose initializer should be obtained.
3235/// \param Version The version of the variable within the frame.
3236/// \param Frame The frame in which the variable was created. Must be null
3237/// if this variable is not local to the evaluation.
3238/// \param Result Filled in with a pointer to the value of the variable.
3239static bool evaluateVarDeclInit(EvalInfo &Info, const Expr *E,
3240 const VarDecl *VD, CallStackFrame *Frame,
3241 unsigned Version, APValue *&Result) {
3242 APValue::LValueBase Base(VD, Frame ? Frame->Index : 0, Version);
3243
3244 // If this is a local variable, dig out its value.
3245 if (Frame) {
3246 Result = Frame->getTemporary(VD, Version);
3247 if (Result)
3248 return true;
3249
3250 if (!isa<ParmVarDecl>(VD)) {
3251 // Assume variables referenced within a lambda's call operator that were
3252 // not declared within the call operator are captures and during checking
3253 // of a potential constant expression, assume they are unknown constant
3254 // expressions.
3255 assert(isLambdaCallOperator(Frame->Callee) &&
3256 (VD->getDeclContext() != Frame->Callee || VD->isInitCapture()) &&
3257 "missing value for local variable");
3258 if (Info.checkingPotentialConstantExpression())
3259 return false;
3260 // FIXME: This diagnostic is bogus; we do support captures. Is this code
3261 // still reachable at all?
3262 Info.FFDiag(E->getBeginLoc(),
3263 diag::note_unimplemented_constexpr_lambda_feature_ast)
3264 << "captures not currently allowed";
3265 return false;
3266 }
3267 }
3268
3269 // If we're currently evaluating the initializer of this declaration, use that
3270 // in-flight value.
3271 if (Info.EvaluatingDecl == Base) {
3272 Result = Info.EvaluatingDeclValue;
3273 return true;
3274 }
3275
3276 if (isa<ParmVarDecl>(VD)) {
3277 // Assume parameters of a potential constant expression are usable in
3278 // constant expressions.
3279 if (!Info.checkingPotentialConstantExpression() ||
3280 !Info.CurrentCall->Callee ||
3281 !Info.CurrentCall->Callee->Equals(VD->getDeclContext())) {
3282 if (Info.getLangOpts().CPlusPlus11) {
3283 Info.FFDiag(E, diag::note_constexpr_function_param_value_unknown)
3284 << VD;
3285 NoteLValueLocation(Info, Base);
3286 } else {
3287 Info.FFDiag(E);
3288 }
3289 }
3290 return false;
3291 }
3292
3293 // Dig out the initializer, and use the declaration which it's attached to.
3294 // FIXME: We should eventually check whether the variable has a reachable
3295 // initializing declaration.
3296 const Expr *Init = VD->getAnyInitializer(VD);
3297 if (!Init) {
3298 // Don't diagnose during potential constant expression checking; an
3299 // initializer might be added later.
3300 if (!Info.checkingPotentialConstantExpression()) {
3301 Info.FFDiag(E, diag::note_constexpr_var_init_unknown, 1)
3302 << VD;
3303 NoteLValueLocation(Info, Base);
3304 }
3305 return false;
3306 }
3307
3308 if (Init->isValueDependent()) {
3309 // The DeclRefExpr is not value-dependent, but the variable it refers to
3310 // has a value-dependent initializer. This should only happen in
3311 // constant-folding cases, where the variable is not actually of a suitable
3312 // type for use in a constant expression (otherwise the DeclRefExpr would
3313 // have been value-dependent too), so diagnose that.
3314 assert(!VD->mightBeUsableInConstantExpressions(Info.Ctx));
3315 if (!Info.checkingPotentialConstantExpression()) {
3316 Info.FFDiag(E, Info.getLangOpts().CPlusPlus11
3317 ? diag::note_constexpr_ltor_non_constexpr
3318 : diag::note_constexpr_ltor_non_integral, 1)
3319 << VD << VD->getType();
3320 NoteLValueLocation(Info, Base);
3321 }
3322 return false;
3323 }
3324
3325 // Check that we can fold the initializer. In C++, we will have already done
3326 // this in the cases where it matters for conformance.
3327 if (!VD->evaluateValue()) {
3328 Info.FFDiag(E, diag::note_constexpr_var_init_non_constant, 1) << VD;
3329 NoteLValueLocation(Info, Base);
3330 return false;
3331 }
3332
3333 // Check that the variable is actually usable in constant expressions. For a
3334 // const integral variable or a reference, we might have a non-constant
3335 // initializer that we can nonetheless evaluate the initializer for. Such
3336 // variables are not usable in constant expressions. In C++98, the
3337 // initializer also syntactically needs to be an ICE.
3338 //
3339 // FIXME: We don't diagnose cases that aren't potentially usable in constant
3340 // expressions here; doing so would regress diagnostics for things like
3341 // reading from a volatile constexpr variable.
3342 if ((Info.getLangOpts().CPlusPlus && !VD->hasConstantInitialization() &&
3343 VD->mightBeUsableInConstantExpressions(Info.Ctx)) ||
3344 ((Info.getLangOpts().CPlusPlus || Info.getLangOpts().OpenCL) &&
3345 !Info.getLangOpts().CPlusPlus11 && !VD->hasICEInitializer(Info.Ctx))) {
3346 Info.CCEDiag(E, diag::note_constexpr_var_init_non_constant, 1) << VD;
3347 NoteLValueLocation(Info, Base);
3348 }
3349
3350 // Never use the initializer of a weak variable, not even for constant
3351 // folding. We can't be sure that this is the definition that will be used.
3352 if (VD->isWeak()) {
3353 Info.FFDiag(E, diag::note_constexpr_var_init_weak) << VD;
3354 NoteLValueLocation(Info, Base);
3355 return false;
3356 }
3357
3358 Result = VD->getEvaluatedValue();
3359 return true;
3360}
3361
3362/// Get the base index of the given base class within an APValue representing
3363/// the given derived class.
3364static unsigned getBaseIndex(const CXXRecordDecl *Derived,
3365 const CXXRecordDecl *Base) {
3366 Base = Base->getCanonicalDecl();
3367 unsigned Index = 0;
3369 E = Derived->bases_end(); I != E; ++I, ++Index) {
3370 if (I->getType()->getAsCXXRecordDecl()->getCanonicalDecl() == Base)
3371 return Index;
3372 }
3373
3374 llvm_unreachable("base class missing from derived class's bases list");
3375}
3376
3377/// Extract the value of a character from a string literal.
3378static APSInt extractStringLiteralCharacter(EvalInfo &Info, const Expr *Lit,
3379 uint64_t Index) {
3380 assert(!isa<SourceLocExpr>(Lit) &&
3381 "SourceLocExpr should have already been converted to a StringLiteral");
3382
3383 // FIXME: Support MakeStringConstant
3384 if (const auto *ObjCEnc = dyn_cast<ObjCEncodeExpr>(Lit)) {
3385 std::string Str;
3386 Info.Ctx.getObjCEncodingForType(ObjCEnc->getEncodedType(), Str);
3387 assert(Index <= Str.size() && "Index too large");
3388 return APSInt::getUnsigned(Str.c_str()[Index]);
3389 }
3390
3391 if (auto PE = dyn_cast<PredefinedExpr>(Lit))
3392 Lit = PE->getFunctionName();
3393 const StringLiteral *S = cast<StringLiteral>(Lit);
3394 const ConstantArrayType *CAT =
3395 Info.Ctx.getAsConstantArrayType(S->getType());
3396 assert(CAT && "string literal isn't an array");
3397 QualType CharType = CAT->getElementType();
3398 assert(CharType->isIntegerType() && "unexpected character type");
3399
3400 APSInt Value(S->getCharByteWidth() * Info.Ctx.getCharWidth(),
3401 CharType->isUnsignedIntegerType());
3402 if (Index < S->getLength())
3403 Value = S->getCodeUnit(Index);
3404 return Value;
3405}
3406
3407// Expand a string literal into an array of characters.
3408//
3409// FIXME: This is inefficient; we should probably introduce something similar
3410// to the LLVM ConstantDataArray to make this cheaper.
3411static void expandStringLiteral(EvalInfo &Info, const StringLiteral *S,
3412 APValue &Result,
3413 QualType AllocType = QualType()) {
3414 const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(
3415 AllocType.isNull() ? S->getType() : AllocType);
3416 assert(CAT && "string literal isn't an array");
3417 QualType CharType = CAT->getElementType();
3418 assert(CharType->isIntegerType() && "unexpected character type");
3419
3420 unsigned Elts = CAT->getSize().getZExtValue();
3421 Result = APValue(APValue::UninitArray(),
3422 std::min(S->getLength(), Elts), Elts);
3423 APSInt Value(S->getCharByteWidth() * Info.Ctx.getCharWidth(),
3424 CharType->isUnsignedIntegerType());
3425 if (Result.hasArrayFiller())
3426 Result.getArrayFiller() = APValue(Value);
3427 for (unsigned I = 0, N = Result.getArrayInitializedElts(); I != N; ++I) {
3428 Value = S->getCodeUnit(I);
3429 Result.getArrayInitializedElt(I) = APValue(Value);
3430 }
3431}
3432
3433// Expand an array so that it has more than Index filled elements.
3434static void expandArray(APValue &Array, unsigned Index) {
3435 unsigned Size = Array.getArraySize();
3436 assert(Index < Size);
3437
3438 // Always at least double the number of elements for which we store a value.
3439 unsigned OldElts = Array.getArrayInitializedElts();
3440 unsigned NewElts = std::max(Index+1, OldElts * 2);
3441 NewElts = std::min(Size, std::max(NewElts, 8u));
3442
3443 // Copy the data across.
3444 APValue NewValue(APValue::UninitArray(), NewElts, Size);
3445 for (unsigned I = 0; I != OldElts; ++I)
3446 NewValue.getArrayInitializedElt(I).swap(Array.getArrayInitializedElt(I));
3447 for (unsigned I = OldElts; I != NewElts; ++I)
3448 NewValue.getArrayInitializedElt(I) = Array.getArrayFiller();
3449 if (NewValue.hasArrayFiller())
3450 NewValue.getArrayFiller() = Array.getArrayFiller();
3451 Array.swap(NewValue);
3452}
3453
3454/// Determine whether a type would actually be read by an lvalue-to-rvalue
3455/// conversion. If it's of class type, we may assume that the copy operation
3456/// is trivial. Note that this is never true for a union type with fields
3457/// (because the copy always "reads" the active member) and always true for
3458/// a non-class type.
3459static bool isReadByLvalueToRvalueConversion(const CXXRecordDecl *RD);
3462 return !RD || isReadByLvalueToRvalueConversion(RD);
3463}
3465 // FIXME: A trivial copy of a union copies the object representation, even if
3466 // the union is empty.
3467 if (RD->isUnion())
3468 return !RD->field_empty();
3469 if (RD->isEmpty())
3470 return false;
3471
3472 for (auto *Field : RD->fields())
3473 if (!Field->isUnnamedBitfield() &&
3474 isReadByLvalueToRvalueConversion(Field->getType()))
3475 return true;
3476
3477 for (auto &BaseSpec : RD->bases())
3478 if (isReadByLvalueToRvalueConversion(BaseSpec.getType()))
3479 return true;
3480
3481 return false;
3482}
3483
3484/// Diagnose an attempt to read from any unreadable field within the specified
3485/// type, which might be a class type.
3486static bool diagnoseMutableFields(EvalInfo &Info, const Expr *E, AccessKinds AK,
3487 QualType T) {
3489 if (!RD)
3490 return false;
3491
3492 if (!RD->hasMutableFields())
3493 return false;
3494
3495 for (auto *Field : RD->fields()) {
3496 // If we're actually going to read this field in some way, then it can't
3497 // be mutable. If we're in a union, then assigning to a mutable field
3498 // (even an empty one) can change the active member, so that's not OK.
3499 // FIXME: Add core issue number for the union case.
3500 if (Field->isMutable() &&
3501 (RD->isUnion() || isReadByLvalueToRvalueConversion(Field->getType()))) {
3502 Info.FFDiag(E, diag::note_constexpr_access_mutable, 1) << AK << Field;
3503 Info.Note(Field->getLocation(), diag::note_declared_at);
3504 return true;
3505 }
3506
3507 if (diagnoseMutableFields(Info, E, AK, Field->getType()))
3508 return true;
3509 }
3510
3511 for (auto &BaseSpec : RD->bases())
3512 if (diagnoseMutableFields(Info, E, AK, BaseSpec.getType()))
3513 return true;
3514
3515 // All mutable fields were empty, and thus not actually read.
3516 return false;
3517}
3518
3519static bool lifetimeStartedInEvaluation(EvalInfo &Info,
3521 bool MutableSubobject = false) {
3522 // A temporary or transient heap allocation we created.
3523 if (Base.getCallIndex() || Base.is<DynamicAllocLValue>())
3524 return true;
3525
3526 switch (Info.IsEvaluatingDecl) {
3527 case EvalInfo::EvaluatingDeclKind::None:
3528 return false;
3529
3530 case EvalInfo::EvaluatingDeclKind::Ctor:
3531 // The variable whose initializer we're evaluating.
3532 if (Info.EvaluatingDecl == Base)
3533 return true;
3534
3535 // A temporary lifetime-extended by the variable whose initializer we're
3536 // evaluating.
3537 if (auto *BaseE = Base.dyn_cast<const Expr *>())
3538 if (auto *BaseMTE = dyn_cast<MaterializeTemporaryExpr>(BaseE))
3539 return Info.EvaluatingDecl == BaseMTE->getExtendingDecl();
3540 return false;
3541
3542 case EvalInfo::EvaluatingDeclKind::Dtor:
3543 // C++2a [expr.const]p6:
3544 // [during constant destruction] the lifetime of a and its non-mutable
3545 // subobjects (but not its mutable subobjects) [are] considered to start
3546 // within e.
3547 if (MutableSubobject || Base != Info.EvaluatingDecl)
3548 return false;
3549 // FIXME: We can meaningfully extend this to cover non-const objects, but
3550 // we will need special handling: we should be able to access only
3551 // subobjects of such objects that are themselves declared const.
3552 QualType T = getType(Base);
3553 return T.isConstQualified() || T->isReferenceType();
3554 }
3555
3556 llvm_unreachable("unknown evaluating decl kind");
3557}
3558
3559namespace {
3560/// A handle to a complete object (an object that is not a subobject of
3561/// another object).
3562struct CompleteObject {
3563 /// The identity of the object.
3565 /// The value of the complete object.
3566 APValue *Value;
3567 /// The type of the complete object.
3568 QualType Type;
3569
3570 CompleteObject() : Value(nullptr) {}
3572 : Base(Base), Value(Value), Type(Type) {}
3573
3574 bool mayAccessMutableMembers(EvalInfo &Info, AccessKinds AK) const {
3575 // If this isn't a "real" access (eg, if it's just accessing the type
3576 // info), allow it. We assume the type doesn't change dynamically for
3577 // subobjects of constexpr objects (even though we'd hit UB here if it
3578 // did). FIXME: Is this right?
3579 if (!isAnyAccess(AK))
3580 return true;
3581
3582 // In C++14 onwards, it is permitted to read a mutable member whose
3583 // lifetime began within the evaluation.
3584 // FIXME: Should we also allow this in C++11?
3585 if (!Info.getLangOpts().CPlusPlus14)
3586 return false;
3587 return lifetimeStartedInEvaluation(Info, Base, /*MutableSubobject*/true);
3588 }
3589
3590 explicit operator bool() const { return !Type.isNull(); }
3591};
3592} // end anonymous namespace
3593
3594static QualType getSubobjectType(QualType ObjType, QualType SubobjType,
3595 bool IsMutable = false) {
3596 // C++ [basic.type.qualifier]p1:
3597 // - A const object is an object of type const T or a non-mutable subobject
3598 // of a const object.
3599 if (ObjType.isConstQualified() && !IsMutable)
3600 SubobjType.addConst();
3601 // - A volatile object is an object of type const T or a subobject of a
3602 // volatile object.
3603 if (ObjType.isVolatileQualified())
3604 SubobjType.addVolatile();
3605 return SubobjType;
3606}
3607
3608/// Find the designated sub-object of an rvalue.
3609template<typename SubobjectHandler>
3610typename SubobjectHandler::result_type
3611findSubobject(EvalInfo &Info, const Expr *E, const CompleteObject &Obj,
3612 const SubobjectDesignator &Sub, SubobjectHandler &handler) {
3613 if (Sub.Invalid)
3614 // A diagnostic will have already been produced.
3615 return handler.failed();
3616 if (Sub.isOnePastTheEnd() || Sub.isMostDerivedAnUnsizedArray()) {
3617 if (Info.getLangOpts().CPlusPlus11)
3618 Info.FFDiag(E, Sub.isOnePastTheEnd()
3619 ? diag::note_constexpr_access_past_end
3620 : diag::note_constexpr_access_unsized_array)
3621 << handler.AccessKind;
3622 else
3623 Info.FFDiag(E);
3624 return handler.failed();
3625 }
3626
3627 APValue *O = Obj.Value;
3628 QualType ObjType = Obj.Type;
3629 const FieldDecl *LastField = nullptr;
3630 const FieldDecl *VolatileField = nullptr;
3631
3632 // Walk the designator's path to find the subobject.
3633 for (unsigned I = 0, N = Sub.Entries.size(); /**/; ++I) {
3634 // Reading an indeterminate value is undefined, but assigning over one is OK.
3635 if ((O->isAbsent() && !(handler.AccessKind == AK_Construct && I == N)) ||
3636 (O->isIndeterminate() &&
3637 !isValidIndeterminateAccess(handler.AccessKind))) {
3638 if (!Info.checkingPotentialConstantExpression())
3639 Info.FFDiag(E, diag::note_constexpr_access_uninit)
3640 << handler.AccessKind << O->isIndeterminate();
3641 return handler.failed();
3642 }
3643
3644 // C++ [class.ctor]p5, C++ [class.dtor]p5:
3645 // const and volatile semantics are not applied on an object under
3646 // {con,de}struction.
3647 if ((ObjType.isConstQualified() || ObjType.isVolatileQualified()) &&
3648 ObjType->isRecordType() &&
3649 Info.isEvaluatingCtorDtor(
3650 Obj.Base,
3651 llvm::ArrayRef(Sub.Entries.begin(), Sub.Entries.begin() + I)) !=
3652 ConstructionPhase::None) {
3653 ObjType = Info.Ctx.getCanonicalType(ObjType);
3654 ObjType.removeLocalConst();
3655 ObjType.removeLocalVolatile();
3656 }
3657
3658 // If this is our last pass, check that the final object type is OK.
3659 if (I == N || (I == N - 1 && ObjType->isAnyComplexType())) {
3660 // Accesses to volatile objects are prohibited.
3661 if (ObjType.isVolatileQualified() && isFormalAccess(handler.AccessKind)) {
3662 if (Info.getLangOpts().CPlusPlus) {
3663 int DiagKind;
3664 SourceLocation Loc;
3665 const NamedDecl *Decl = nullptr;
3666 if (VolatileField) {
3667 DiagKind = 2;
3668 Loc = VolatileField->getLocation();
3669 Decl = VolatileField;
3670 } else if (auto *VD = Obj.Base.dyn_cast<const ValueDecl*>()) {
3671 DiagKind = 1;
3672 Loc = VD->getLocation();
3673 Decl = VD;
3674 } else {
3675 DiagKind = 0;
3676 if (auto *E = Obj.Base.dyn_cast<const Expr *>())
3677 Loc = E->getExprLoc();
3678 }
3679 Info.FFDiag(E, diag::note_constexpr_access_volatile_obj, 1)
3680 << handler.AccessKind << DiagKind << Decl;
3681 Info.Note(Loc, diag::note_constexpr_volatile_here) << DiagKind;
3682 } else {
3683 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
3684 }
3685 return handler.failed();
3686 }
3687
3688 // If we are reading an object of class type, there may still be more
3689 // things we need to check: if there are any mutable subobjects, we
3690 // cannot perform this read. (This only happens when performing a trivial
3691 // copy or assignment.)
3692 if (ObjType->isRecordType() &&
3693 !Obj.mayAccessMutableMembers(Info, handler.AccessKind) &&
3694 diagnoseMutableFields(Info, E, handler.AccessKind, ObjType))
3695 return handler.failed();
3696 }
3697
3698 if (I == N) {
3699 if (!handler.found(*O, ObjType))
3700 return false;
3701
3702 // If we modified a bit-field, truncate it to the right width.
3703 if (isModification(handler.AccessKind) &&
3704 LastField && LastField->isBitField() &&
3705 !truncateBitfieldValue(Info, E, *O, LastField))
3706 return false;
3707
3708 return true;
3709 }
3710
3711 LastField = nullptr;
3712 if (ObjType->isArrayType()) {
3713 // Next subobject is an array element.
3714 const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(ObjType);
3715 assert(CAT && "vla in literal type?");
3716 uint64_t Index = Sub.Entries[I].getAsArrayIndex();
3717 if (CAT->getSize().ule(Index)) {
3718 // Note, it should not be possible to form a pointer with a valid
3719 // designator which points more than one past the end of the array.
3720 if (Info.getLangOpts().CPlusPlus11)
3721 Info.FFDiag(E, diag::note_constexpr_access_past_end)
3722 << handler.AccessKind;
3723 else
3724 Info.FFDiag(E);
3725 return handler.failed();
3726 }
3727
3728 ObjType = CAT->getElementType();
3729
3730 if (O->getArrayInitializedElts() > Index)
3731 O = &O->getArrayInitializedElt(Index);
3732 else if (!isRead(handler.AccessKind)) {
3733 expandArray(*O, Index);
3734 O = &O->getArrayInitializedElt(Index);
3735 } else
3736 O = &O->getArrayFiller();
3737 } else if (ObjType->isAnyComplexType()) {
3738 // Next subobject is a complex number.
3739 uint64_t Index = Sub.Entries[I].getAsArrayIndex();
3740 if (Index > 1) {
3741 if (Info.getLangOpts().CPlusPlus11)
3742 Info.FFDiag(E, diag::note_constexpr_access_past_end)
3743 << handler.AccessKind;
3744 else
3745 Info.FFDiag(E);
3746 return handler.failed();
3747 }
3748
3749 ObjType = getSubobjectType(
3750 ObjType, ObjType->castAs<ComplexType>()->getElementType());
3751
3752 assert(I == N - 1 && "extracting subobject of scalar?");
3753 if (O->isComplexInt()) {
3754 return handler.found(Index ? O->getComplexIntImag()
3755 : O->getComplexIntReal(), ObjType);
3756 } else {
3757 assert(O->isComplexFloat());
3758 return handler.found(Index ? O->getComplexFloatImag()
3759 : O->getComplexFloatReal(), ObjType);
3760 }
3761 } else if (const FieldDecl *Field = getAsField(Sub.Entries[I])) {
3762 if (Field->isMutable() &&
3763 !Obj.mayAccessMutableMembers(Info, handler.AccessKind)) {
3764 Info.FFDiag(E, diag::note_constexpr_access_mutable, 1)
3765 << handler.AccessKind << Field;
3766 Info.Note(Field->getLocation(), diag::note_declared_at);
3767 return handler.failed();
3768 }
3769
3770 // Next subobject is a class, struct or union field.
3771 RecordDecl *RD = ObjType->castAs<RecordType>()->getDecl();
3772 if (RD->isUnion()) {
3773 const FieldDecl *UnionField = O->getUnionField();
3774 if (!UnionField ||
3775 UnionField->getCanonicalDecl() != Field->getCanonicalDecl()) {
3776 if (I == N - 1 && handler.AccessKind == AK_Construct) {
3777 // Placement new onto an inactive union member makes it active.
3778 O->setUnion(Field, APValue());
3779 } else {
3780 // FIXME: If O->getUnionValue() is absent, report that there's no
3781 // active union member rather than reporting the prior active union
3782 // member. We'll need to fix nullptr_t to not use APValue() as its
3783 // representation first.
3784 Info.FFDiag(E, diag::note_constexpr_access_inactive_union_member)
3785 << handler.AccessKind << Field << !UnionField << UnionField;
3786 return handler.failed();
3787 }
3788 }
3789 O = &O->getUnionValue();
3790 } else
3791 O = &O->getStructField(Field->getFieldIndex());
3792
3793 ObjType = getSubobjectType(ObjType, Field->getType(), Field->isMutable());
3794 LastField = Field;
3795 if (Field->getType().isVolatileQualified())
3796 VolatileField = Field;
3797 } else {
3798 // Next subobject is a base class.
3799 const CXXRecordDecl *Derived = ObjType->getAsCXXRecordDecl();
3800 const CXXRecordDecl *Base = getAsBaseClass(Sub.Entries[I]);
3801 O = &O->getStructBase(getBaseIndex(Derived, Base));
3802
3803 ObjType = getSubobjectType(ObjType, Info.Ctx.getRecordType(Base));
3804 }
3805 }
3806}
3807
3808namespace {
3809struct ExtractSubobjectHandler {
3810 EvalInfo &Info;
3811 const Expr *E;
3812 APValue &Result;
3813 const AccessKinds AccessKind;
3814
3815 typedef bool result_type;
3816 bool failed() { return false; }
3817 bool found(APValue &Subobj, QualType SubobjType) {
3818 Result = Subobj;
3819 if (AccessKind == AK_ReadObjectRepresentation)
3820 return true;
3821 return CheckFullyInitialized(Info, E->getExprLoc(), SubobjType, Result);
3822 }
3823 bool found(APSInt &Value, QualType SubobjType) {
3824 Result = APValue(Value);
3825 return true;
3826 }
3827 bool found(APFloat &Value, QualType SubobjType) {
3828 Result = APValue(Value);
3829 return true;
3830 }
3831};
3832} // end anonymous namespace
3833
3834/// Extract the designated sub-object of an rvalue.
3835static bool extractSubobject(EvalInfo &Info, const Expr *E,
3836 const CompleteObject &Obj,
3837 const SubobjectDesignator &Sub, APValue &Result,
3838 AccessKinds AK = AK_Read) {
3839 assert(AK == AK_Read || AK == AK_ReadObjectRepresentation);
3840 ExtractSubobjectHandler Handler = {Info, E, Result, AK};
3841 return findSubobject(Info, E, Obj, Sub, Handler);
3842}
3843
3844namespace {
3845struct ModifySubobjectHandler {
3846 EvalInfo &Info;
3847 APValue &NewVal;
3848 const Expr *E;
3849
3850 typedef bool result_type;
3851 static const AccessKinds AccessKind = AK_Assign;
3852
3853 bool checkConst(QualType QT) {
3854 // Assigning to a const object has undefined behavior.
3855 if (QT.isConstQualified()) {
3856 Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT;
3857 return false;
3858 }
3859 return true;
3860 }
3861
3862 bool failed() { return false; }
3863 bool found(APValue &Subobj, QualType SubobjType) {
3864 if (!checkConst(SubobjType))
3865 return false;
3866 // We've been given ownership of NewVal, so just swap it in.
3867 Subobj.swap(NewVal);
3868 return true;
3869 }
3870 bool found(APSInt &Value, QualType SubobjType) {
3871 if (!checkConst(SubobjType))
3872 return false;
3873 if (!NewVal.isInt()) {
3874 // Maybe trying to write a cast pointer value into a complex?
3875 Info.FFDiag(E);
3876 return false;
3877 }
3878 Value = NewVal.getInt();
3879 return true;
3880 }
3881 bool found(APFloat &Value, QualType SubobjType) {
3882 if (!checkConst(SubobjType))
3883 return false;
3884 Value = NewVal.getFloat();
3885 return true;
3886 }
3887};
3888} // end anonymous namespace
3889
3890const AccessKinds ModifySubobjectHandler::AccessKind;
3891
3892/// Update the designated sub-object of an rvalue to the given value.
3893static bool modifySubobject(EvalInfo &Info, const Expr *E,
3894 const CompleteObject &Obj,
3895 const SubobjectDesignator &Sub,
3896 APValue &NewVal) {
3897 ModifySubobjectHandler Handler = { Info, NewVal, E };
3898 return findSubobject(Info, E, Obj, Sub, Handler);
3899}
3900
3901/// Find the position where two subobject designators diverge, or equivalently
3902/// the length of the common initial subsequence.
3903static unsigned FindDesignatorMismatch(QualType ObjType,
3904 const SubobjectDesignator &A,
3905 const SubobjectDesignator &B,
3906 bool &WasArrayIndex) {
3907 unsigned I = 0, N = std::min(A.Entries.size(), B.Entries.size());
3908 for (/**/; I != N; ++I) {
3909 if (!ObjType.isNull() &&
3910 (ObjType->isArrayType() || ObjType->isAnyComplexType())) {
3911 // Next subobject is an array element.
3912 if (A.Entries[I].getAsArrayIndex() != B.Entries[I].getAsArrayIndex()) {
3913 WasArrayIndex = true;
3914 return I;
3915 }
3916 if (ObjType->isAnyComplexType())
3917 ObjType = ObjType->castAs<ComplexType>()->getElementType();
3918 else
3919 ObjType = ObjType->castAsArrayTypeUnsafe()->getElementType();
3920 } else {
3921 if (A.Entries[I].getAsBaseOrMember() !=
3922 B.Entries[I].getAsBaseOrMember()) {
3923 WasArrayIndex = false;
3924 return I;
3925 }
3926 if (const FieldDecl *FD = getAsField(A.Entries[I]))
3927 // Next subobject is a field.
3928 ObjType = FD->getType();
3929 else
3930 // Next subobject is a base class.
3931 ObjType = QualType();
3932 }
3933 }
3934 WasArrayIndex = false;
3935 return I;
3936}
3937
3938/// Determine whether the given subobject designators refer to elements of the
3939/// same array object.
3941 const SubobjectDesignator &A,
3942 const SubobjectDesignator &B) {
3943 if (A.Entries.size() != B.Entries.size())
3944 return false;
3945
3946 bool IsArray = A.MostDerivedIsArrayElement;
3947 if (IsArray && A.MostDerivedPathLength != A.Entries.size())
3948 // A is a subobject of the array element.
3949 return false;
3950
3951 // If A (and B) designates an array element, the last entry will be the array
3952 // index. That doesn't have to match. Otherwise, we're in the 'implicit array
3953 // of length 1' case, and the entire path must match.
3954 bool WasArrayIndex;
3955 unsigned CommonLength = FindDesignatorMismatch(ObjType, A, B, WasArrayIndex);
3956 return CommonLength >= A.Entries.size() - IsArray;
3957}
3958
3959/// Find the complete object to which an LValue refers.
3960static CompleteObject findCompleteObject(EvalInfo &Info, const Expr *E,
3961 AccessKinds AK, const LValue &LVal,
3962 QualType LValType) {
3963 if (LVal.InvalidBase) {
3964 Info.FFDiag(E);
3965 return CompleteObject();
3966 }
3967
3968 if (!LVal.Base) {
3969 Info.FFDiag(E, diag::note_constexpr_access_null) << AK;
3970 return CompleteObject();
3971 }
3972
3973 CallStackFrame *Frame = nullptr;
3974 unsigned Depth = 0;
3975 if (LVal.getLValueCallIndex()) {
3976 std::tie(Frame, Depth) =
3977 Info.getCallFrameAndDepth(LVal.getLValueCallIndex());
3978 if (!Frame) {
3979 Info.FFDiag(E, diag::note_constexpr_lifetime_ended, 1)
3980 << AK << LVal.Base.is<const ValueDecl*>();
3981 NoteLValueLocation(Info, LVal.Base);
3982 return CompleteObject();
3983 }
3984 }
3985
3986 bool IsAccess = isAnyAccess(AK);
3987
3988 // C++11 DR1311: An lvalue-to-rvalue conversion on a volatile-qualified type
3989 // is not a constant expression (even if the object is non-volatile). We also
3990 // apply this rule to C++98, in order to conform to the expected 'volatile'
3991 // semantics.
3992 if (isFormalAccess(AK) && LValType.isVolatileQualified()) {
3993 if (Info.getLangOpts().CPlusPlus)
3994 Info.FFDiag(E, diag::note_constexpr_access_volatile_type)
3995 << AK << LValType;
3996 else
3997 Info.FFDiag(E);
3998 return CompleteObject();
3999 }
4000
4001 // Compute value storage location and type of base object.
4002 APValue *BaseVal = nullptr;
4003 QualType BaseType = getType(LVal.Base);
4004
4005 if (Info.getLangOpts().CPlusPlus14 && LVal.Base == Info.EvaluatingDecl &&
4006 lifetimeStartedInEvaluation(Info, LVal.Base)) {
4007 // This is the object whose initializer we're evaluating, so its lifetime
4008 // started in the current evaluation.
4009 BaseVal = Info.EvaluatingDeclValue;
4010 } else if (const ValueDecl *D = LVal.Base.dyn_cast<const ValueDecl *>()) {
4011 // Allow reading from a GUID declaration.
4012 if (auto *GD = dyn_cast<MSGuidDecl>(D)) {
4013 if (isModification(AK)) {
4014 // All the remaining cases do not permit modification of the object.
4015 Info.FFDiag(E, diag::note_constexpr_modify_global);
4016 return CompleteObject();
4017 }
4018 APValue &V = GD->getAsAPValue();
4019 if (V.isAbsent()) {
4020 Info.FFDiag(E, diag::note_constexpr_unsupported_layout)
4021 << GD->getType();
4022 return CompleteObject();
4023 }
4024 return CompleteObject(LVal.Base, &V, GD->getType());
4025 }
4026
4027 // Allow reading the APValue from an UnnamedGlobalConstantDecl.
4028 if (auto *GCD = dyn_cast<UnnamedGlobalConstantDecl>(D)) {
4029 if (isModification(AK)) {
4030 Info.FFDiag(E, diag::note_constexpr_modify_global);
4031 return CompleteObject();
4032 }
4033 return CompleteObject(LVal.Base, const_cast<APValue *>(&GCD->getValue()),
4034 GCD->getType());
4035 }
4036
4037 // Allow reading from template parameter objects.
4038 if (auto *TPO = dyn_cast<TemplateParamObjectDecl>(D)) {
4039 if (isModification(AK)) {
4040 Info.FFDiag(E, diag::note_constexpr_modify_global);
4041 return CompleteObject();
4042 }
4043 return CompleteObject(LVal.Base, const_cast<APValue *>(&TPO->getValue()),
4044 TPO->getType());
4045 }
4046
4047 // In C++98, const, non-volatile integers initialized with ICEs are ICEs.
4048 // In C++11, constexpr, non-volatile variables initialized with constant
4049 // expressions are constant expressions too. Inside constexpr functions,
4050 // parameters are constant expressions even if they're non-const.
4051 // In C++1y, objects local to a constant expression (those with a Frame) are
4052 // both readable and writable inside constant expressions.
4053 // In C, such things can also be folded, although they are not ICEs.
4054 const VarDecl *VD = dyn_cast<VarDecl>(D);
4055 if (VD) {
4056 if (const VarDecl *VDef = VD->getDefinition(Info.Ctx))
4057 VD = VDef;
4058 }
4059 if (!VD || VD->isInvalidDecl()) {
4060 Info.FFDiag(E);
4061 return CompleteObject();
4062 }
4063
4064 bool IsConstant = BaseType.isConstant(Info.Ctx);
4065
4066 // Unless we're looking at a local variable or argument in a constexpr call,
4067 // the variable we're reading must be const.
4068 if (!Frame) {
4069 if (IsAccess && isa<ParmVarDecl>(VD)) {
4070 // Access of a parameter that's not associated with a frame isn't going
4071 // to work out, but we can leave it to evaluateVarDeclInit to provide a
4072 // suitable diagnostic.
4073 } else if (Info.getLangOpts().CPlusPlus14 &&
4074 lifetimeStartedInEvaluation(Info, LVal.Base)) {
4075 // OK, we can read and modify an object if we're in the process of
4076 // evaluating its initializer, because its lifetime began in this
4077 // evaluation.
4078 } else if (isModification(AK)) {
4079 // All the remaining cases do not permit modification of the object.
4080 Info.FFDiag(E, diag::note_constexpr_modify_global);
4081 return CompleteObject();
4082 } else if (VD->isConstexpr()) {
4083 // OK, we can read this variable.
4084 } else if (BaseType->isIntegralOrEnumerationType()) {
4085 if (!IsConstant) {
4086 if (!IsAccess)
4087 return CompleteObject(LVal.getLValueBase(), nullptr, BaseType);
4088 if (Info.getLangOpts().CPlusPlus) {
4089 Info.FFDiag(E, diag::note_constexpr_ltor_non_const_int, 1) << VD;
4090 Info.Note(VD->getLocation(), diag::note_declared_at);
4091 } else {
4092 Info.FFDiag(E);
4093 }
4094 return CompleteObject();
4095 }
4096 } else if (!IsAccess) {
4097 return CompleteObject(LVal.getLValueBase(), nullptr, BaseType);
4098 } else if (IsConstant && Info.checkingPotentialConstantExpression() &&
4099 BaseType->isLiteralType(Info.Ctx) && !VD->hasDefinition()) {
4100 // This variable might end up being constexpr. Don't diagnose it yet.
4101 } else if (IsConstant) {
4102 // Keep evaluating to see what we can do. In particular, we support
4103 // folding of const floating-point types, in order to make static const
4104 // data members of such types (supported as an extension) more useful.
4105 if (Info.getLangOpts().CPlusPlus) {
4106 Info.CCEDiag(E, Info.getLangOpts().CPlusPlus11
4107 ? diag::note_constexpr_ltor_non_constexpr
4108 : diag::note_constexpr_ltor_non_integral, 1)
4109 << VD << BaseType;
4110 Info.Note(VD->getLocation(), diag::note_declared_at);
4111 } else {
4112 Info.CCEDiag(E);
4113 }
4114 } else {
4115 // Never allow reading a non-const value.
4116 if (Info.getLangOpts().CPlusPlus) {
4117 Info.FFDiag(E, Info.getLangOpts().CPlusPlus11
4118 ? diag::note_constexpr_ltor_non_constexpr
4119 : diag::note_constexpr_ltor_non_integral, 1)
4120 << VD << BaseType;
4121 Info.Note(VD->getLocation(), diag::note_declared_at);
4122 } else {
4123 Info.FFDiag(E);
4124 }
4125 return CompleteObject();
4126 }
4127 }
4128
4129 if (!evaluateVarDeclInit(Info, E, VD, Frame, LVal.getLValueVersion(), BaseVal))
4130 return CompleteObject();
4131 } else if (DynamicAllocLValue DA = LVal.Base.dyn_cast<DynamicAllocLValue>()) {
4132 std::optional<DynAlloc *> Alloc = Info.lookupDynamicAlloc(DA);
4133 if (!Alloc) {
4134 Info.FFDiag(E, diag::note_constexpr_access_deleted_object) << AK;
4135 return CompleteObject();
4136 }
4137 return CompleteObject(LVal.Base, &(*Alloc)->Value,
4138 LVal.Base.getDynamicAllocType());
4139 } else {
4140 const Expr *Base = LVal.Base.dyn_cast<const Expr*>();
4141
4142 if (!Frame) {
4143 if (const MaterializeTemporaryExpr *MTE =
4144 dyn_cast_or_null<MaterializeTemporaryExpr>(Base)) {
4145 assert(MTE->getStorageDuration() == SD_Static &&
4146 "should have a frame for a non-global materialized temporary");
4147
4148 // C++20 [expr.const]p4: [DR2126]
4149 // An object or reference is usable in constant expressions if it is
4150 // - a temporary object of non-volatile const-qualified literal type
4151 // whose lifetime is extended to that of a variable that is usable
4152 // in constant expressions
4153 //
4154 // C++20 [expr.const]p5:
4155 // an lvalue-to-rvalue conversion [is not allowed unless it applies to]
4156 // - a non-volatile glvalue that refers to an object that is usable
4157 // in constant expressions, or
4158 // - a non-volatile glvalue of literal type that refers to a
4159 // non-volatile object whose lifetime began within the evaluation
4160 // of E;
4161 //
4162 // C++11 misses the 'began within the evaluation of e' check and
4163 // instead allows all temporaries, including things like:
4164 // int &&r = 1;
4165 // int x = ++r;
4166 // constexpr int k = r;
4167 // Therefore we use the C++14-onwards rules in C++11 too.
4168 //
4169 // Note that temporaries whose lifetimes began while evaluating a
4170 // variable's constructor are not usable while evaluating the
4171 // corresponding destructor, not even if they're of const-qualified
4172 // types.
4173 if (!MTE->isUsableInConstantExpressions(Info.Ctx) &&
4174 !lifetimeStartedInEvaluation(Info, LVal.Base)) {
4175 if (!IsAccess)
4176 return CompleteObject(LVal.getLValueBase(), nullptr, BaseType);
4177 Info.FFDiag(E, diag::note_constexpr_access_static_temporary, 1) << AK;
4178 Info.Note(MTE->getExprLoc(), diag::note_constexpr_temporary_here);
4179 return CompleteObject();
4180 }
4181
4182 BaseVal = MTE->getOrCreateValue(false);
4183 assert(BaseVal && "got reference to unevaluated temporary");
4184 } else {
4185 if (!IsAccess)
4186 return CompleteObject(LVal.getLValueBase(), nullptr, BaseType);
4187 APValue Val;
4188 LVal.moveInto(Val);
4189 Info.FFDiag(E, diag::note_constexpr_access_unreadable_object)
4190 << AK
4191 << Val.getAsString(Info.Ctx,
4192 Info.Ctx.getLValueReferenceType(LValType));
4193 NoteLValueLocation(Info, LVal.Base);
4194 return CompleteObject();
4195 }
4196 } else {
4197 BaseVal = Frame->getTemporary(Base, LVal.Base.getVersion());
4198 assert(BaseVal && "missing value for temporary");
4199 }
4200 }
4201
4202 // In C++14, we can't safely access any mutable state when we might be
4203 // evaluating after an unmodeled side effect. Parameters are modeled as state
4204 // in the caller, but aren't visible once the call returns, so they can be
4205 // modified in a speculatively-evaluated call.
4206 //
4207 // FIXME: Not all local state is mutable. Allow local constant subobjects
4208 // to be read here (but take care with 'mutable' fields).
4209 unsigned VisibleDepth = Depth;
4210 if (llvm::isa_and_nonnull<ParmVarDecl>(
4211 LVal.Base.dyn_cast<const ValueDecl *>()))
4212 ++VisibleDepth;
4213 if ((Frame && Info.getLangOpts().CPlusPlus14 &&
4214 Info.EvalStatus.HasSideEffects) ||
4215 (isModification(AK) && VisibleDepth < Info.SpeculativeEvaluationDepth))
4216 return CompleteObject();
4217
4218 return CompleteObject(LVal.getLValueBase(), BaseVal, BaseType);
4219}
4220
4221/// Perform an lvalue-to-rvalue conversion on the given glvalue. This
4222/// can also be used for 'lvalue-to-lvalue' conversions for looking up the
4223/// glvalue referred to by an entity of reference type.
4224///
4225/// \param Info - Information about the ongoing evaluation.
4226/// \param Conv - The expression for which we are performing the conversion.
4227/// Used for diagnostics.
4228/// \param Type - The type of the glvalue (before stripping cv-qualifiers in the
4229/// case of a non-class type).
4230/// \param LVal - The glvalue on which we are attempting to perform this action.
4231/// \param RVal - The produced value will be placed here.
4232/// \param WantObjectRepresentation - If true, we're looking for the object
4233/// representation rather than the value, and in particular,
4234/// there is no requirement that the result be fully initialized.
4235static bool
4237 const LValue &LVal, APValue &RVal,
4238 bool WantObjectRepresentation = false) {
4239 if (LVal.Designator.Invalid)
4240 return false;
4241
4242 // Check for special cases where there is no existing APValue to look at.
4243 const Expr *Base = LVal.Base.dyn_cast<const Expr*>();
4244
4245 AccessKinds AK =
4246 WantObjectRepresentation ? AK_ReadObjectRepresentation : AK_Read;
4247
4248 if (Base && !LVal.getLValueCallIndex() && !Type.isVolatileQualified()) {
4249 if (const CompoundLiteralExpr *CLE = dyn_cast<CompoundLiteralExpr>(Base)) {
4250 // In C99, a CompoundLiteralExpr is an lvalue, and we defer evaluating the
4251 // initializer until now for such expressions. Such an expression can't be
4252 // an ICE in C, so this only matters for fold.
4253 if (Type.isVolatileQualified()) {
4254 Info.FFDiag(Conv);
4255 return false;
4256 }
4257
4258 APValue Lit;
4259 if (!Evaluate(Lit, Info, CLE->getInitializer()))
4260 return false;
4261
4262 // According to GCC info page:
4263 //
4264 // 6.28 Compound Literals
4265 //
4266 // As an optimization, G++ sometimes gives array compound literals longer
4267 // lifetimes: when the array either appears outside a function or has a
4268 // const-qualified type. If foo and its initializer had elements of type
4269 // char *const rather than char *, or if foo were a global variable, the
4270 // array would have static storage duration. But it is probably safest
4271 // just to avoid the use of array compound literals in C++ code.
4272 //
4273 // Obey that rule by checking constness for converted array types.
4274
4275 QualType CLETy = CLE->getType();
4276 if (CLETy->isArrayType() && !Type->isArrayType()) {
4277 if (!CLETy.isConstant(Info.Ctx)) {
4278 Info.FFDiag(Conv);
4279 Info.Note(CLE->getExprLoc(), diag::note_declared_at);
4280 return false;
4281 }
4282 }
4283
4284 CompleteObject LitObj(LVal.Base, &Lit, Base->getType());
4285 return extractSubobject(Info, Conv, LitObj, LVal.Designator, RVal, AK);
4286 } else if (isa<StringLiteral>(Base) || isa<PredefinedExpr>(Base)) {
4287 // Special-case character extraction so we don't have to construct an
4288 // APValue for the whole string.
4289 assert(LVal.Designator.Entries.size() <= 1 &&
4290 "Can only read characters from string literals");
4291 if (LVal.Designator.Entries.empty()) {
4292 // Fail for now for LValue to RValue conversion of an array.
4293 // (This shouldn't show up in C/C++, but it could be triggered by a
4294 // weird EvaluateAsRValue call from a tool.)
4295 Info.FFDiag(Conv);
4296 return false;
4297 }
4298 if (LVal.Designator.isOnePastTheEnd()) {
4299 if (Info.getLangOpts().CPlusPlus11)
4300 Info.FFDiag(Conv, diag::note_constexpr_access_past_end) << AK;
4301 else
4302 Info.FFDiag(Conv);
4303 return false;
4304 }
4305 uint64_t CharIndex = LVal.Designator.Entries[0].getAsArrayIndex();
4306 RVal = APValue(extractStringLiteralCharacter(Info, Base, CharIndex));
4307 return true;
4308 }
4309 }
4310
4311 CompleteObject Obj = findCompleteObject(Info, Conv, AK, LVal, Type);
4312 return Obj && extractSubobject(Info, Conv, Obj, LVal.Designator, RVal, AK);
4313}
4314
4315/// Perform an assignment of Val to LVal. Takes ownership of Val.
4316static bool handleAssignment(EvalInfo &Info, const Expr *E, const LValue &LVal,
4317 QualType LValType, APValue &Val) {
4318 if (LVal.Designator.Invalid)
4319 return false;
4320
4321 if (!Info.getLangOpts().CPlusPlus14) {
4322 Info.FFDiag(E);
4323 return false;
4324 }
4325
4326 CompleteObject Obj = findCompleteObject(Info, E, AK_Assign, LVal, LValType);
4327 return Obj && modifySubobject(Info, E, Obj, LVal.Designator, Val);
4328}
4329
4330namespace {
4331struct CompoundAssignSubobjectHandler {
4332 EvalInfo &Info;
4333 const CompoundAssignOperator *E;
4334 QualType PromotedLHSType;
4336 const APValue &RHS;
4337
4338 static const AccessKinds AccessKind = AK_Assign;
4339
4340 typedef bool result_type;
4341
4342 bool checkConst(QualType QT) {
4343 // Assigning to a const object has undefined behavior.
4344 if (QT.isConstQualified()) {
4345 Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT;
4346 return false;
4347 }
4348 return true;
4349 }
4350
4351 bool failed() { return false; }
4352 bool found(APValue &Subobj, QualType SubobjType) {
4353 switch (Subobj.getKind()) {
4354 case APValue::Int:
4355 return found(Subobj.getInt(), SubobjType);
4356 case APValue::Float:
4357 return found(Subobj.getFloat(), SubobjType);
4360 // FIXME: Implement complex compound assignment.
4361 Info.FFDiag(E);
4362 return false;
4363 case APValue::LValue:
4364 return foundPointer(Subobj, SubobjType);
4365 case APValue::Vector:
4366 return foundVector(Subobj, SubobjType);
4367 default:
4368 // FIXME: can this happen?
4369 Info.FFDiag(E);
4370 return false;
4371 }
4372 }
4373
4374 bool foundVector(APValue &Value, QualType SubobjType) {
4375 if (!checkConst(SubobjType))
4376 return false;
4377
4378 if (!SubobjType->isVectorType()) {
4379 Info.FFDiag(E);
4380 return false;
4381 }
4382 return handleVectorVectorBinOp(Info, E, Opcode, Value, RHS);
4383 }
4384
4385 bool found(APSInt &Value, QualType SubobjType) {
4386 if (!checkConst(SubobjType))
4387 return false;
4388
4389 if (!SubobjType->isIntegerType()) {
4390 // We don't support compound assignment on integer-cast-to-pointer
4391 // values.
4392 Info.FFDiag(E);
4393 return false;
4394 }
4395
4396 if (RHS.isInt()) {
4397 APSInt LHS =
4398 HandleIntToIntCast(Info, E, PromotedLHSType, SubobjType, Value);
4399 if (!handleIntIntBinOp(Info, E, LHS, Opcode, RHS.getInt(), LHS))
4400 return false;
4401 Value = HandleIntToIntCast(Info, E, SubobjType, PromotedLHSType, LHS);
4402 return true;
4403 } else if (RHS.isFloat()) {
4404 const FPOptions FPO = E->getFPFeaturesInEffect(
4405 Info.Ctx.getLangOpts());
4406 APFloat FValue(0.0);
4407 return HandleIntToFloatCast(Info, E, FPO, SubobjType, Value,
4408 PromotedLHSType, FValue) &&
4409 handleFloatFloatBinOp(Info, E, FValue, Opcode, RHS.getFloat()) &&
4410 HandleFloatToIntCast(Info, E, PromotedLHSType, FValue, SubobjType,
4411 Value);
4412 }
4413
4414 Info.FFDiag(E);
4415 return false;
4416 }
4417 bool found(APFloat &Value, QualType SubobjType) {
4418 return checkConst(SubobjType) &&
4419 HandleFloatToFloatCast(Info, E, SubobjType, PromotedLHSType,
4420 Value) &&
4421 handleFloatFloatBinOp(Info, E, Value, Opcode, RHS.getFloat()) &&
4422 HandleFloatToFloatCast(Info, E, PromotedLHSType, SubobjType, Value);
4423 }
4424 bool foundPointer(APValue &Subobj, QualType SubobjType) {
4425 if (!checkConst(SubobjType))
4426 return false;
4427
4428 QualType PointeeType;
4429 if (const PointerType *PT = SubobjType->getAs<PointerType>())
4430 PointeeType = PT->getPointeeType();
4431
4432 if (PointeeType.isNull() || !RHS.isInt() ||
4433 (Opcode != BO_Add && Opcode != BO_Sub)) {
4434 Info.FFDiag(E);
4435 return false;
4436 }
4437
4438 APSInt Offset = RHS.getInt();
4439 if (Opcode == BO_Sub)
4441
4442 LValue LVal;
4443 LVal.setFrom(Info.Ctx, Subobj);
4444 if (!HandleLValueArrayAdjustment(Info, E, LVal, PointeeType, Offset))
4445 return false;
4446 LVal.moveInto(Subobj);
4447 return true;
4448 }
4449};
4450} // end anonymous namespace
4451
4452const AccessKinds CompoundAssignSubobjectHandler::AccessKind;
4453
4454/// Perform a compound assignment of LVal <op>= RVal.
4455static bool handleCompoundAssignment(EvalInfo &Info,
4456 const CompoundAssignOperator *E,
4457 const LValue &LVal, QualType LValType,
4458 QualType PromotedLValType,
4459 BinaryOperatorKind Opcode,
4460 const APValue &RVal) {
4461 if (LVal.Designator.Invalid)
4462 return false;
4463
4464 if (!Info.getLangOpts().CPlusPlus14) {
4465 Info.FFDiag(E);
4466 return false;
4467 }
4468
4469 CompleteObject Obj = findCompleteObject(Info, E, AK_Assign, LVal, LValType);
4470 CompoundAssignSubobjectHandler Handler = { Info, E, PromotedLValType, Opcode,
4471 RVal };
4472 return Obj && findSubobject(Info, E, Obj, LVal.Designator, Handler);
4473}
4474
4475namespace {
4476struct IncDecSubobjectHandler {
4477 EvalInfo &Info;
4478 const UnaryOperator *E;
4479 AccessKinds AccessKind;
4480 APValue *Old;
4481
4482 typedef bool result_type;
4483
4484 bool checkConst(QualType QT) {
4485 // Assigning to a const object has undefined behavior.
4486 if (QT.isConstQualified()) {
4487 Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT;
4488 return false;
4489 }
4490 return true;
4491 }
4492
4493 bool failed() { return false; }
4494 bool found(APValue &Subobj, QualType SubobjType) {
4495 // Stash the old value. Also clear Old, so we don't clobber it later
4496 // if we're post-incrementing a complex.
4497 if (Old) {
4498 *Old = Subobj;
4499 Old = nullptr;
4500 }
4501
4502 switch (Subobj.getKind()) {
4503 case APValue::Int:
4504 return found(Subobj.getInt(), SubobjType);
4505 case APValue::Float:
4506 return found(Subobj.getFloat(), SubobjType);
4508 return found(Subobj.getComplexIntReal(),
4509 SubobjType->castAs<ComplexType>()->getElementType()
4510 .withCVRQualifiers(SubobjType.getCVRQualifiers()));
4512 return found(Subobj.getComplexFloatReal(),
4513 SubobjType->castAs<ComplexType>()->getElementType()
4514 .withCVRQualifiers(SubobjType.getCVRQualifiers()));
4515 case APValue::LValue:
4516 return foundPointer(Subobj, SubobjType);
4517 default:
4518 // FIXME: can this happen?
4519 Info.FFDiag(E);
4520 return false;
4521 }
4522 }
4523 bool found(APSInt &Value, QualType SubobjType) {
4524 if (!checkConst(SubobjType))
4525 return false;
4526
4527 if (!SubobjType->isIntegerType()) {
4528 // We don't support increment / decrement on integer-cast-to-pointer
4529 // values.
4530 Info.FFDiag(E);
4531 return false;
4532 }
4533
4534 if (Old) *Old = APValue(Value);
4535
4536 // bool arithmetic promotes to int, and the conversion back to bool
4537 // doesn't reduce mod 2^n, so special-case it.
4538 if (SubobjType->isBooleanType()) {
4539 if (AccessKind == AK_Increment)
4540 Value = 1;
4541 else
4542 Value = !Value;
4543 return true;
4544 }
4545
4546 bool WasNegative = Value.isNegative();
4547 if (AccessKind == AK_Increment) {
4548 ++Value;
4549
4550 if (!WasNegative && Value.isNegative() && E->canOverflow()) {
4551 APSInt ActualValue(Value, /*IsUnsigned*/true);
4552 return HandleOverflow(Info, E, ActualValue, SubobjType);
4553 }
4554 } else {
4555 --Value;
4556
4557 if (WasNegative && !Value.isNegative() && E->canOverflow()) {
4558 unsigned BitWidth = Value.getBitWidth();
4559 APSInt ActualValue(Value.sext(BitWidth + 1), /*IsUnsigned*/false);
4560 ActualValue.setBit(BitWidth);
4561 return HandleOverflow(Info, E, ActualValue, SubobjType);
4562 }
4563 }
4564 return true;
4565 }
4566 bool found(APFloat &Value, QualType SubobjType) {
4567 if (!checkConst(SubobjType))
4568 return false;
4569
4570 if (Old) *Old = APValue(Value);
4571
4572 APFloat One(Value.getSemantics(), 1);
4573 if (AccessKind == AK_Increment)
4574 Value.add(One, APFloat::rmNearestTiesToEven);
4575 else
4576 Value.subtract(One, APFloat::rmNearestTiesToEven);
4577 return true;
4578 }
4579 bool foundPointer(APValue &Subobj, QualType SubobjType) {
4580 if (!checkConst(SubobjType))
4581 return false;
4582
4583 QualType PointeeType;
4584 if (const PointerType *PT = SubobjType->getAs<PointerType>())
4585 PointeeType = PT->getPointeeType();
4586 else {
4587 Info.FFDiag(E);
4588 return false;
4589 }
4590
4591 LValue LVal;
4592 LVal.setFrom(Info.Ctx, Subobj);
4593 if (!HandleLValueArrayAdjustment(Info, E, LVal, PointeeType,
4594 AccessKind == AK_Increment ? 1 : -1))
4595 return false;
4596 LVal.moveInto(Subobj);
4597 return true;
4598 }
4599};
4600} // end anonymous namespace
4601
4602/// Perform an increment or decrement on LVal.
4603static bool handleIncDec(EvalInfo &Info, const Expr *E, const LValue &LVal,
4604 QualType LValType, bool IsIncrement, APValue *Old) {
4605 if (LVal.Designator.Invalid)
4606 return false;
4607
4608 if (!Info.getLangOpts().CPlusPlus14) {
4609 Info.FFDiag(E);
4610 return false;
4611 }
4612
4613 AccessKinds AK = IsIncrement ? AK_Increment : AK_Decrement;
4614 CompleteObject Obj = findCompleteObject(Info, E, AK, LVal, LValType);
4615 IncDecSubobjectHandler Handler = {Info, cast<UnaryOperator>(E), AK, Old};
4616 return Obj && findSubobject(Info, E, Obj, LVal.Designator, Handler);
4617}
4618
4619/// Build an lvalue for the object argument of a member function call.
4620static bool EvaluateObjectArgument(EvalInfo &Info, const Expr *Object,
4621 LValue &This) {
4622 if (Object->getType()->isPointerType() && Object->isPRValue())
4623 return EvaluatePointer(Object, This, Info);
4624
4625 if (Object->isGLValue())
4626 return EvaluateLValue(Object, This, Info);
4627
4628 if (Object->getType()->isLiteralType(Info.Ctx))
4629 return EvaluateTemporary(Object, This, Info);
4630
4631 Info.FFDiag(Object, diag::note_constexpr_nonliteral) << Object->getType();
4632 return false;
4633}
4634
4635/// HandleMemberPointerAccess - Evaluate a member access operation and build an
4636/// lvalue referring to the result.
4637///
4638/// \param Info - Information about the ongoing evaluation.
4639/// \param LV - An lvalue referring to the base of the member pointer.
4640/// \param RHS - The member pointer expression.
4641/// \param IncludeMember - Specifies whether the member itself is included in
4642/// the resulting LValue subobject designator. This is not possible when
4643/// creating a bound member function.
4644/// \return The field or method declaration to which the member pointer refers,
4645/// or 0 if evaluation fails.
4646static const ValueDecl *HandleMemberPointerAccess(EvalInfo &Info,
4647 QualType LVType,
4648 LValue &LV,
4649 const Expr *RHS,
4650 bool IncludeMember = true) {
4651 MemberPtr MemPtr;
4652 if (!EvaluateMemberPointer(RHS, MemPtr, Info))
4653 return nullptr;
4654
4655 // C++11 [expr.mptr.oper]p6: If the second operand is the null pointer to
4656 // member value, the behavior is undefined.
4657 if (!MemPtr.getDecl()) {
4658 // FIXME: Specific diagnostic.
4659 Info.FFDiag(RHS);
4660 return nullptr;
4661 }
4662
4663 if (MemPtr.isDerivedMember()) {
4664 // This is a member of some derived class. Truncate LV appropriately.
4665 // The end of the derived-to-base path for the base object must match the
4666 // derived-to-base path for the member pointer.
4667 if (LV.Designator.MostDerivedPathLength + MemPtr.Path.size() >
4668 LV.Designator.Entries.size()) {
4669 Info.FFDiag(RHS);
4670 return nullptr;
4671 }
4672 unsigned PathLengthToMember =
4673 LV.Designator.Entries.size() - MemPtr.Path.size();
4674 for (unsigned I = 0, N = MemPtr.Path.size(); I != N; ++I) {
4675 const CXXRecordDecl *LVDecl = getAsBaseClass(
4676 LV.Designator.Entries[PathLengthToMember + I]);
4677 const CXXRecordDecl *MPDecl = MemPtr.Path[I];
4678 if (LVDecl->getCanonicalDecl() != MPDecl->getCanonicalDecl()) {
4679 Info.FFDiag(RHS);
4680 return nullptr;
4681 }
4682 }
4683
4684 // Truncate the lvalue to the appropriate derived class.
4685 if (!CastToDerivedClass(Info, RHS, LV, MemPtr.getContainingRecord(),
4686 PathLengthToMember))
4687 return nullptr;
4688 } else if (!MemPtr.Path.empty()) {
4689 // Extend the LValue path with the member pointer's path.
4690 LV.Designator.Entries.reserve(LV.Designator.Entries.size() +
4691 MemPtr.Path.size() + IncludeMember);
4692
4693 // Walk down to the appropriate base class.
4694 if (const PointerType *PT = LVType->getAs<PointerType>())
4695 LVType = PT->getPointeeType();
4696 const CXXRecordDecl *RD = LVType->getAsCXXRecordDecl();
4697 assert(RD && "member pointer access on non-class-type expression");
4698 // The first class in the path is that of the lvalue.
4699 for (unsigned I = 1, N = MemPtr.Path.size(); I != N; ++I) {
4700 const CXXRecordDecl *Base = MemPtr.Path[N - I - 1];
4701 if (!HandleLValueDirectBase(Info, RHS, LV, RD, Base))
4702 return nullptr;
4703 RD = Base;
4704 }
4705 // Finally cast to the class containing the member.
4706 if (!HandleLValueDirectBase(Info, RHS, LV, RD,
4707 MemPtr.getContainingRecord()))
4708 return nullptr;
4709 }
4710
4711 // Add the member. Note that we cannot build bound member functions here.
4712 if (IncludeMember) {
4713 if (const FieldDecl *FD = dyn_cast<FieldDecl>(MemPtr.getDecl())) {
4714 if (!HandleLValueMember(Info, RHS, LV, FD))
4715 return nullptr;
4716 } else if (const IndirectFieldDecl *IFD =
4717 dyn_cast<IndirectFieldDecl>(MemPtr.getDecl())) {
4718 if (!HandleLValueIndirectMember(Info, RHS, LV, IFD))
4719 return nullptr;
4720 } else {
4721 llvm_unreachable("can't construct reference to bound member function");
4722 }
4723 }
4724
4725 return MemPtr.getDecl();
4726}
4727
4728static const ValueDecl *HandleMemberPointerAccess(EvalInfo &Info,
4729 const BinaryOperator *BO,
4730 LValue &LV,
4731 bool IncludeMember = true) {
4732 assert(BO->getOpcode() == BO_PtrMemD || BO->getOpcode() == BO_PtrMemI);
4733
4734 if (!EvaluateObjectArgument(Info, BO->getLHS(), LV)) {
4735 if (Info.noteFailure()) {
4736 MemberPtr MemPtr;
4737 EvaluateMemberPointer(BO->getRHS(), MemPtr, Info);
4738 }
4739 return nullptr;
4740 }
4741
4742 return HandleMemberPointerAccess(Info, BO->getLHS()->getType(), LV,
4743 BO->getRHS(), IncludeMember);
4744}
4745
4746/// HandleBaseToDerivedCast - Apply the given base-to-derived cast operation on
4747/// the provided lvalue, which currently refers to the base object.
4748static bool HandleBaseToDerivedCast(EvalInfo &Info, const CastExpr *E,
4749 LValue &Result) {
4750 SubobjectDesignator &D = Result.Designator;
4751 if (D.Invalid || !Result.checkNullPointer(Info, E, CSK_Derived))
4752 return false;
4753
4754 QualType TargetQT = E->getType();
4755 if (const PointerType *PT = TargetQT->getAs<PointerType>())
4756 TargetQT = PT->getPointeeType();
4757
4758 // Check this cast lands within the final derived-to-base subobject path.
4759 if (D.MostDerivedPathLength + E->path_size() > D.Entries.size()) {
4760 Info.CCEDiag(E, diag::note_constexpr_invalid_downcast)
4761 << D.MostDerivedType << TargetQT;
4762 return false;
4763 }
4764
4765 // Check the type of the final cast. We don't need to check the path,
4766 // since a cast can only be formed if the path is unique.
4767 unsigned NewEntriesSize = D.Entries.size() - E->path_size();
4768 const CXXRecordDecl *TargetType = TargetQT->getAsCXXRecordDecl();
4769 const CXXRecordDecl *FinalType;
4770 if (NewEntriesSize == D.MostDerivedPathLength)
4771 FinalType = D.MostDerivedType->getAsCXXRecordDecl();
4772 else
4773 FinalType = getAsBaseClass(D.Entries[NewEntriesSize - 1]);
4774 if (FinalType->getCanonicalDecl() != TargetType->getCanonicalDecl()) {
4775 Info.CCEDiag(E, diag::note_constexpr_invalid_downcast)
4776 << D.MostDerivedType << TargetQT;
4777 return false;
4778 }
4779
4780 // Truncate the lvalue to the appropriate derived class.
4781 return CastToDerivedClass(Info, E, Result, TargetType, NewEntriesSize);
4782}
4783
4784/// Get the value to use for a default-initialized object of type T.
4785/// Return false if it encounters something invalid.
4786static bool getDefaultInitValue(QualType T, APValue &Result) {
4787 bool Success = true;
4788 if (auto *RD = T->getAsCXXRecordDecl()) {
4789 if (RD->isInvalidDecl()) {
4790 Result = APValue();
4791 return false;
4792 }
4793 if (RD->isUnion()) {
4794 Result = APValue((const FieldDecl *)nullptr);
4795 return true;
4796 }
4797 Result = APValue(APValue::UninitStruct(), RD->getNumBases(),
4798 std::distance(RD->field_begin(), RD->field_end()));
4799
4800 unsigned Index = 0;
4801 for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
4802 End = RD->bases_end();
4803 I != End; ++I, ++Index)
4804 Success &= getDefaultInitValue(I->getType(), Result.getStructBase(Index));
4805
4806 for (const auto *I : RD->fields()) {
4807 if (I->isUnnamedBitfield())
4808 continue;
4809 Success &= getDefaultInitValue(I->getType(),
4810 Result.getStructField(I->getFieldIndex()));
4811 }
4812 return Success;
4813 }
4814
4815 if (auto *AT =
4816 dyn_cast_or_null<ConstantArrayType>(T->getAsArrayTypeUnsafe())) {
4817 Result = APValue(APValue::UninitArray(), 0, AT->getSize().getZExtValue());
4818 if (Result.hasArrayFiller())
4819 Success &=
4820 getDefaultInitValue(AT->getElementType(), Result.getArrayFiller());
4821
4822 return Success;
4823 }
4824
4825 Result = APValue::IndeterminateValue();
4826 return true;
4827}
4828
4829namespace {
4830enum EvalStmtResult {
4831 /// Evaluation failed.
4832 ESR_Failed,
4833 /// Hit a 'return' statement.
4834 ESR_Returned,
4835 /// Evaluation succeeded.
4836 ESR_Succeeded,
4837 /// Hit a 'continue' statement.
4838 ESR_Continue,
4839 /// Hit a 'break' statement.
4840 ESR_Break,
4841 /// Still scanning for 'case' or 'default' statement.
4842 ESR_CaseNotFound
4843};
4844}
4845
4846static bool EvaluateVarDecl(EvalInfo &Info, const VarDecl *VD) {
4847 if (VD->isInvalidDecl())
4848 return false;
4849 // We don't need to evaluate the initializer for a static local.
4850 if (!VD->hasLocalStorage())
4851 return true;
4852
4853 LValue Result;
4854 APValue &Val = Info.CurrentCall->createTemporary(VD, VD->getType(),
4855 ScopeKind::Block, Result);
4856
4857 const Expr *InitE = VD->getInit();
4858 if (!InitE) {
4859 if (VD->getType()->isDependentType())
4860 return Info.noteSideEffect();
4861 return getDefaultInitValue(VD->getType(), Val);
4862 }
4863 if (InitE->isValueDependent())
4864 return false;
4865
4866 if (!EvaluateInPlace(Val, Info, Result, InitE)) {
4867 // Wipe out any partially-computed value, to allow tracking that this
4868 // evaluation failed.
4869 Val = APValue();
4870 return false;
4871 }
4872
4873 return true;
4874}
4875
4876static bool EvaluateDecl(EvalInfo &Info, const Decl *D) {
4877 bool OK = true;
4878
4879 if (const VarDecl *VD = dyn_cast<VarDecl>(D))
4880 OK &= EvaluateVarDecl(Info, VD);
4881
4882 if (const DecompositionDecl *DD = dyn_cast<DecompositionDecl>(D))
4883 for (auto *BD : DD->bindings())
4884 if (auto *VD = BD->getHoldingVar())
4885 OK &= EvaluateDecl(Info, VD);
4886
4887 return OK;
4888}
4889
4890static bool EvaluateDependentExpr(const Expr *E, EvalInfo &Info) {
4891 assert(E->isValueDependent());
4892 if (Info.noteSideEffect())
4893 return true;
4894 assert(E->containsErrors() && "valid value-dependent expression should never "
4895 "reach invalid code path.");
4896 return false;
4897}
4898
4899/// Evaluate a condition (either a variable declaration or an expression).
4900static bool EvaluateCond(EvalInfo &Info, const VarDecl *CondDecl,
4901 const Expr *Cond, bool &Result) {
4902 if (Cond->isValueDependent())
4903 return false;
4904 FullExpressionRAII Scope(Info);
4905 if (CondDecl && !EvaluateDecl(Info, CondDecl))
4906 return false;
4907 if (!EvaluateAsBooleanCondition(Cond, Result, Info))
4908 return false;
4909 return Scope.destroy();
4910}
4911
4912namespace {
4913/// A location where the result (returned value) of evaluating a
4914/// statement should be stored.
4915struct StmtResult {
4916 /// The APValue that should be filled in with the returned value.
4917 APValue &Value;
4918 /// The location containing the result, if any (used to support RVO).
4919 const LValue *Slot;
4920};
4921
4922struct TempVersionRAII {
4923 CallStackFrame &Frame;
4924
4925 TempVersionRAII(CallStackFrame &Frame) : Frame(Frame) {
4926 Frame.pushTempVersion();
4927 }
4928
4929 ~TempVersionRAII() {
4930 Frame.popTempVersion();
4931 }
4932};
4933
4934}
4935
4936static EvalStmtResult EvaluateStmt(StmtResult &Result, EvalInfo &Info,
4937 const Stmt *S,
4938 const SwitchCase *SC = nullptr);
4939
4940/// Evaluate the body of a loop, and translate the result as appropriate.
4941static EvalStmtResult EvaluateLoopBody(StmtResult &Result, EvalInfo &Info,
4942 const Stmt *Body,
4943 const SwitchCase *Case = nullptr) {
4944 BlockScopeRAII Scope(Info);
4945
4946 EvalStmtResult ESR = EvaluateStmt(Result, Info, Body, Case);
4947 if (ESR != ESR_Failed && ESR != ESR_CaseNotFound && !Scope.destroy())
4948 ESR = ESR_Failed;
4949
4950 switch (ESR) {
4951 case ESR_Break:
4952 return ESR_Succeeded;
4953 case ESR_Succeeded:
4954 case ESR_Continue:
4955 return ESR_Continue;
4956 case ESR_Failed:
4957 case ESR_Returned:
4958 case ESR_CaseNotFound:
4959 return ESR;
4960 }
4961 llvm_unreachable("Invalid EvalStmtResult!");
4962}
4963
4964/// Evaluate a switch statement.
4965static EvalStmtResult EvaluateSwitch(StmtResult &Result, EvalInfo &Info,
4966 const SwitchStmt *SS) {
4967 BlockScopeRAII Scope(Info);
4968
4969 // Evaluate the switch condition.
4970 APSInt Value;
4971 {
4972 if (const Stmt *Init = SS->getInit()) {
4973 EvalStmtResult ESR = EvaluateStmt(Result, Info, Init);
4974 if (ESR != ESR_Succeeded) {
4975 if (ESR != ESR_Failed && !Scope.destroy())
4976 ESR = ESR_Failed;
4977 return ESR;
4978 }
4979 }
4980
4981 FullExpressionRAII CondScope(Info);
4982 if (SS->getConditionVariable() &&
4983 !EvaluateDecl(Info, SS->getConditionVariable()))
4984 return ESR_Failed;
4985 if (SS->getCond()->isValueDependent()) {
4986 if (!EvaluateDependentExpr(SS->getCond(), Info))
4987 return ESR_Failed;
4988 } else {
4989 if (!EvaluateInteger(SS->getCond(), Value, Info))
4990 return ESR_Failed;
4991 }
4992 if (!CondScope.destroy())
4993 return ESR_Failed;
4994 }
4995
4996 // Find the switch case corresponding to the value of the condition.
4997 // FIXME: Cache this lookup.
4998 const SwitchCase *Found = nullptr;
4999 for (const SwitchCase *SC = SS->getSwitchCaseList(); SC;
5000 SC = SC->getNextSwitchCase()) {
5001 if (isa<DefaultStmt>(SC)) {
5002 Found = SC;
5003 continue;
5004 }
5005
5006 const CaseStmt *CS = cast<CaseStmt>(SC);
5007 APSInt LHS = CS->getLHS()->EvaluateKnownConstInt(Info.Ctx);
5008 APSInt RHS = CS->getRHS() ? CS->getRHS()->EvaluateKnownConstInt(Info.Ctx)
5009 : LHS;
5010 if (LHS <= Value && Value <= RHS) {
5011 Found = SC;
5012 break;
5013 }
5014 }
5015
5016 if (!Found)
5017 return Scope.destroy() ? ESR_Succeeded : ESR_Failed;
5018
5019 // Search the switch body for the switch case and evaluate it from there.
5020 EvalStmtResult ESR = EvaluateStmt(Result, Info, SS->getBody(), Found);
5021 if (ESR != ESR_Failed && ESR != ESR_CaseNotFound && !Scope.destroy())
5022 return ESR_Failed;
5023
5024 switch (ESR) {
5025 case ESR_Break:
5026 return ESR_Succeeded;
5027 case ESR_Succeeded:
5028 case ESR_Continue:
5029 case ESR_Failed:
5030 case ESR_Returned:
5031 return ESR;
5032 case ESR_CaseNotFound:
5033 // This can only happen if the switch case is nested within a statement
5034 // expression. We have no intention of supporting that.
5035 Info.FFDiag(Found->getBeginLoc(),
5036 diag::note_constexpr_stmt_expr_unsupported);
5037 return ESR_Failed;
5038 }
5039 llvm_unreachable("Invalid EvalStmtResult!");
5040}
5041
5042static bool CheckLocalVariableDeclaration(EvalInfo &Info, const VarDecl *VD) {
5043 // An expression E is a core constant expression unless the evaluation of E
5044 // would evaluate one of the following: [C++23] - a control flow that passes
5045 // through a declaration of a variable with static or thread storage duration
5046 // unless that variable is usable in constant expressions.
5047 if (VD->isLocalVarDecl() && VD->isStaticLocal() &&
5048 !VD->isUsableInConstantExpressions(Info.Ctx)) {
5049 Info.CCEDiag(VD->getLocation(), diag::note_constexpr_static_local)
5050 << (VD->getTSCSpec() == TSCS_unspecified ? 0 : 1) << VD;
5051 return false;
5052 }
5053 return true;
5054}
5055
5056// Evaluate a statement.
5057static EvalStmtResult EvaluateStmt(StmtResult &Result, EvalInfo &Info,
5058 const Stmt *S, const SwitchCase *Case) {
5059 if (!Info.nextStep(S))
5060 return ESR_Failed;
5061
5062 // If we're hunting down a 'case' or 'default' label, recurse through
5063 // substatements until we hit the label.
5064 if (Case) {
5065 switch (S->getStmtClass()) {
5066 case Stmt::CompoundStmtClass:
5067 // FIXME: Precompute which substatement of a compound statement we
5068 // would jump to, and go straight there rather than performing a
5069 // linear scan each time.
5070 case Stmt::LabelStmtClass:
5071 case Stmt::AttributedStmtClass:
5072 case Stmt::DoStmtClass:
5073 break;
5074
5075 case Stmt::CaseStmtClass:
5076 case Stmt::DefaultStmtClass:
5077 if (Case == S)
5078 Case = nullptr;
5079 break;
5080
5081 case Stmt::IfStmtClass: {
5082 // FIXME: Precompute which side of an 'if' we would jump to, and go
5083 // straight there rather than scanning both sides.
5084 const IfStmt *IS = cast<IfStmt>(S);
5085
5086 // Wrap the evaluation in a block scope, in case it's a DeclStmt
5087 // preceded by our switch label.
5088 BlockScopeRAII Scope(Info);
5089
5090 // Step into the init statement in case it brings an (uninitialized)
5091 // variable into scope.
5092 if (const Stmt *Init = IS->getInit()) {
5093 EvalStmtResult ESR = EvaluateStmt(Result, Info, Init, Case);
5094 if (ESR != ESR_CaseNotFound) {
5095 assert(ESR != ESR_Succeeded);
5096 return ESR;
5097 }
5098 }
5099
5100 // Condition variable must be initialized if it exists.
5101 // FIXME: We can skip evaluating the body if there's a condition
5102 // variable, as there can't be any case labels within it.
5103 // (The same is true for 'for' statements.)
5104
5105 EvalStmtResult ESR = EvaluateStmt(Result, Info, IS->getThen(), Case);
5106 if (ESR == ESR_Failed)
5107 return ESR;
5108 if (ESR != ESR_CaseNotFound)
5109 return Scope.destroy() ? ESR : ESR_Failed;
5110 if (!IS->getElse())
5111 return ESR_CaseNotFound;
5112
5113 ESR = EvaluateStmt(Result, Info, IS->getElse(), Case);
5114 if (ESR == ESR_Failed)
5115 return ESR;
5116 if (ESR != ESR_CaseNotFound)
5117 return Scope.destroy() ? ESR : ESR_Failed;
5118 return ESR_CaseNotFound;
5119 }
5120
5121 case Stmt::WhileStmtClass: {
5122 EvalStmtResult ESR =
5123 EvaluateLoopBody(Result, Info, cast<WhileStmt>(S)->getBody(), Case);
5124 if (ESR != ESR_Continue)
5125 return ESR;
5126 break;
5127 }
5128
5129 case Stmt::ForStmtClass: {
5130 const ForStmt *FS = cast<ForStmt>(S);
5131 BlockScopeRAII Scope(Info);
5132
5133 // Step into the init statement in case it brings an (uninitialized)
5134 // variable into scope.
5135 if (const Stmt *Init = FS->getInit()) {
5136 EvalStmtResult ESR = EvaluateStmt(Result, Info, Init, Case);
5137 if (ESR != ESR_CaseNotFound) {
5138 assert(ESR != ESR_Succeeded);
5139 return ESR;
5140 }
5141 }
5142
5143 EvalStmtResult ESR =
5144 EvaluateLoopBody(Result, Info, FS->getBody(), Case);
5145 if (ESR != ESR_Continue)
5146 return ESR;
5147 if (const auto *Inc = FS->getInc()) {
5148 if (Inc->isValueDependent()) {
5149 if (!EvaluateDependentExpr(Inc, Info))
5150 return ESR_Failed;
5151 } else {
5152 FullExpressionRAII IncScope(Info);
5153 if (!EvaluateIgnoredValue(Info, Inc) || !IncScope.destroy())
5154 return ESR_Failed;
5155 }
5156 }
5157 break;
5158 }
5159
5160 case Stmt::DeclStmtClass: {
5161 // Start the lifetime of any uninitialized variables we encounter. They
5162 // might be used by the selected branch of the switch.
5163 const DeclStmt *DS = cast<DeclStmt>(S);
5164 for (const auto *D : DS->decls()) {
5165 if (const auto *VD = dyn_cast<VarDecl>(D)) {
5166 if (!CheckLocalVariableDeclaration(Info, VD))
5167 return ESR_Failed;
5168 if (VD->hasLocalStorage() && !VD->getInit())
5169 if (!EvaluateVarDecl(Info, VD))
5170 return ESR_Failed;
5171 // FIXME: If the variable has initialization that can't be jumped
5172 // over, bail out of any immediately-surrounding compound-statement
5173 // too. There can't be any case labels here.
5174 }
5175 }
5176 return ESR_CaseNotFound;
5177 }
5178
5179 default:
5180 return ESR_CaseNotFound;
5181 }
5182 }
5183
5184 switch (S->getStmtClass()) {
5185 default:
5186 if (const Expr *E = dyn_cast<Expr>(S)) {
5187 if (E->isValueDependent()) {
5188 if (!EvaluateDependentExpr(E, Info))
5189 return ESR_Failed;
5190 } else {
5191 // Don't bother evaluating beyond an expression-statement which couldn't
5192 // be evaluated.
5193 // FIXME: Do we need the FullExpressionRAII object here?
5194 // VisitExprWithCleanups should create one when necessary.
5195 FullExpressionRAII Scope(Info);
5196 if (!EvaluateIgnoredValue(Info, E) || !Scope.destroy())
5197 return ESR_Failed;
5198 }
5199 return ESR_Succeeded;
5200 }
5201
5202 Info.FFDiag(S->getBeginLoc());
5203 return ESR_Failed;
5204
5205 case Stmt::NullStmtClass:
5206 return ESR_Succeeded;
5207
5208 case Stmt::DeclStmtClass: {
5209 const DeclStmt *DS = cast<DeclStmt>(S);
5210 for (const auto *D : DS->decls()) {
5211 const VarDecl *VD = dyn_cast_or_null<VarDecl>(D);
5212 if (VD && !CheckLocalVariableDeclaration(Info, VD))
5213 return ESR_Failed;
5214 // Each declaration initialization is its own full-expression.
5215 FullExpressionRAII Scope(Info);
5216 if (!EvaluateDecl(Info, D) && !Info.noteFailure())
5217 return ESR_Failed;
5218 if (!Scope.destroy())
5219 return ESR_Failed;
5220 }
5221 return ESR_Succeeded;
5222 }
5223
5224 case Stmt::ReturnStmtClass: {
5225 const Expr *RetExpr = cast<ReturnStmt>(S)->getRetValue();
5226 FullExpressionRAII Scope(Info);
5227 if (RetExpr && RetExpr->isValueDependent()) {
5228 EvaluateDependentExpr(RetExpr, Info);
5229 // We know we returned, but we don't know what the value is.
5230 return ESR_Failed;
5231 }
5232 if (RetExpr &&
5233 !(Result.Slot
5234 ? EvaluateInPlace(Result.Value, Info, *Result.Slot, RetExpr)
5235 : Evaluate(Result.Value, Info, RetExpr)))
5236 return ESR_Failed;
5237 return Scope.destroy() ? ESR_Returned : ESR_Failed;
5238 }
5239
5240 case Stmt::CompoundStmtClass: {
5241 BlockScopeRAII Scope(Info);
5242
5243 const CompoundStmt *CS = cast<CompoundStmt>(S);
5244 for (const auto *BI : CS->body()) {
5245 EvalStmtResult ESR = EvaluateStmt(Result, Info, BI, Case);
5246 if (ESR == ESR_Succeeded)
5247 Case = nullptr;
5248 else if (ESR != ESR_CaseNotFound) {
5249 if (ESR != ESR_Failed && !Scope.destroy())
5250 return ESR_Failed;
5251 return ESR;
5252 }
5253 }
5254 if (Case)
5255 return ESR_CaseNotFound;
5256 return Scope.destroy() ? ESR_Succeeded : ESR_Failed;
5257 }
5258
5259 case Stmt::IfStmtClass: {
5260 const IfStmt *IS = cast<IfStmt>(S);
5261
5262 // Evaluate the condition, as either a var decl or as an expression.
5263 BlockScopeRAII Scope(Info);
5264 if (const Stmt *Init = IS->getInit()) {
5265 EvalStmtResult ESR = EvaluateStmt(Result, Info, Init);
5266 if (ESR != ESR_Succeeded) {
5267 if (ESR != ESR_Failed && !Scope.destroy())
5268 return ESR_Failed;
5269 return ESR;
5270 }
5271 }
5272 bool Cond;
5273 if (IS->isConsteval()) {
5274 Cond = IS->isNonNegatedConsteval();
5275 // If we are not in a constant context, if consteval should not evaluate
5276 // to true.
5277 if (!Info.InConstantContext)
5278 Cond = !Cond;
5279 } else if (!EvaluateCond(Info, IS->getConditionVariable(), IS->getCond(),
5280 Cond))
5281 return ESR_Failed;
5282
5283 if (const Stmt *SubStmt = Cond ? IS->getThen() : IS->getElse()) {
5284 EvalStmtResult ESR = EvaluateStmt(Result, Info, SubStmt);
5285 if (ESR != ESR_Succeeded) {
5286 if (ESR != ESR_Failed && !Scope.destroy())
5287 return ESR_Failed;
5288 return ESR;
5289 }
5290 }
5291 return Scope.destroy() ? ESR_Succeeded : ESR_Failed;
5292 }
5293
5294 case Stmt::WhileStmtClass: {
5295 const WhileStmt *WS = cast<WhileStmt>(S);
5296 while (true) {
5297 BlockScopeRAII Scope(Info);
5298 bool Continue;
5299 if (!EvaluateCond(Info, WS->getConditionVariable(), WS->getCond(),
5300 Continue))
5301 return ESR_Failed;
5302 if (!Continue)
5303 break;
5304
5305 EvalStmtResult ESR = EvaluateLoopBody(Result, Info, WS->getBody());
5306 if (ESR != ESR_Continue) {
5307 if (ESR != ESR_Failed && !Scope.destroy())
5308 return ESR_Failed;
5309 return ESR;
5310 }
5311 if (!Scope.destroy())
5312 return ESR_Failed;
5313 }
5314 return ESR_Succeeded;
5315 }
5316
5317 case Stmt::DoStmtClass: {
5318 const DoStmt *DS = cast<DoStmt>(S);
5319 bool Continue;
5320 do {
5321 EvalStmtResult ESR = EvaluateLoopBody(Result, Info, DS->getBody(), Case);
5322 if (ESR != ESR_Continue)
5323 return ESR;
5324 Case = nullptr;
5325
5326 if (DS->getCond()->isValueDependent()) {
5327 EvaluateDependentExpr(DS->getCond(), Info);
5328 // Bailout as we don't know whether to keep going or terminate the loop.
5329 return ESR_Failed;
5330 }
5331 FullExpressionRAII CondScope(Info);
5332 if (!EvaluateAsBooleanCondition(DS->getCond(), Continue, Info) ||
5333 !CondScope.destroy())
5334 return ESR_Failed;
5335 } while (Continue);
5336 return ESR_Succeeded;
5337 }
5338
5339 case Stmt::ForStmtClass: {
5340 const ForStmt *FS = cast<ForStmt>(S);
5341 BlockScopeRAII ForScope(Info);
5342 if (FS->getInit()) {
5343 EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getInit());
5344 if (ESR != ESR_Succeeded) {
5345 if (ESR != ESR_Failed && !ForScope.destroy())
5346 return ESR_Failed;
5347 return ESR;
5348 }
5349 }
5350 while (true) {
5351 BlockScopeRAII IterScope(Info);
5352 bool Continue = true;
5353 if (FS->getCond() && !EvaluateCond(Info, FS->getConditionVariable(),
5354 FS->getCond(), Continue))
5355 return ESR_Failed;
5356 if (!Continue)
5357 break;
5358
5359 EvalStmtResult ESR = EvaluateLoopBody(Result, Info, FS->getBody());
5360 if (ESR != ESR_Continue) {
5361 if (ESR != ESR_Failed && (!IterScope.destroy() || !ForScope.destroy()))
5362 return ESR_Failed;
5363 return ESR;
5364 }
5365
5366 if (const auto *Inc = FS->getInc()) {
5367 if (Inc->isValueDependent()) {
5368 if (!EvaluateDependentExpr(Inc, Info))
5369 return ESR_Failed;
5370 } else {
5371 FullExpressionRAII IncScope(Info);
5372 if (!EvaluateIgnoredValue(Info, Inc) || !IncScope.destroy())
5373 return ESR_Failed;
5374 }
5375 }
5376
5377 if (!IterScope.destroy())
5378 return ESR_Failed;
5379 }
5380 return ForScope.destroy() ? ESR_Succeeded : ESR_Failed;
5381 }
5382
5383 case Stmt::CXXForRangeStmtClass: {
5384 const CXXForRangeStmt *FS = cast<CXXForRangeStmt>(S);
5385 BlockScopeRAII Scope(Info);
5386
5387 // Evaluate the init-statement if present.
5388 if (FS->getInit()) {
5389 EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getInit());
5390 if (ESR != ESR_Succeeded) {
5391 if (ESR != ESR_Failed && !Scope.destroy())
5392 return ESR_Failed;
5393 return ESR;
5394 }
5395 }
5396
5397 // Initialize the __range variable.
5398 EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getRangeStmt());
5399 if (ESR != ESR_Succeeded) {
5400 if (ESR != ESR_Failed && !Scope.destroy())
5401 return ESR_Failed;
5402 return ESR;
5403 }
5404
5405 // In error-recovery cases it's possible to get here even if we failed to
5406 // synthesize the __begin and __end variables.
5407 if (!FS->getBeginStmt() || !FS->getEndStmt() || !FS->getCond())
5408 return ESR_Failed;
5409
5410 // Create the __begin and __end iterators.
5411 ESR = EvaluateStmt(Result, Info, FS->getBeginStmt());
5412 if (ESR != ESR_Succeeded) {
5413 if (ESR != ESR_Failed && !Scope.destroy())
5414 return ESR_Failed;
5415 return ESR;
5416 }
5417 ESR = EvaluateStmt(Result, Info, FS->getEndStmt());
5418 if (ESR != ESR_Succeeded) {
5419 if (ESR != ESR_Failed && !Scope.destroy())
5420 return ESR_Failed;
5421 return ESR;
5422 }
5423
5424 while (true) {
5425 // Condition: __begin != __end.
5426 {
5427 if (FS->getCond()->isValueDependent()) {
5428 EvaluateDependentExpr(FS->getCond(), Info);
5429 // We don't know whether to keep going or terminate the loop.
5430 return ESR_Failed;
5431 }
5432 bool Continue = true;
5433 FullExpressionRAII CondExpr(Info);
5434 if (!EvaluateAsBooleanCondition(FS->getCond(), Continue, Info))
5435 return ESR_Failed;
5436 if (!Continue)
5437 break;
5438 }
5439
5440 // User's variable declaration, initialized by *__begin.
5441 BlockScopeRAII InnerScope(Info);
5442 ESR = EvaluateStmt(Result, Info, FS->getLoopVarStmt());
5443 if (ESR != ESR_Succeeded) {
5444 if (ESR != ESR_Failed && (!InnerScope.destroy() || !Scope.destroy()))
5445 return ESR_Failed;
5446 return ESR;
5447 }
5448
5449 // Loop body.
5450 ESR = EvaluateLoopBody(Result, Info, FS->getBody());
5451 if (ESR != ESR_Continue) {
5452 if (ESR != ESR_Failed && (!InnerScope.destroy() || !Scope.destroy()))
5453 return ESR_Failed;
5454 return ESR;
5455 }
5456 if (FS->getInc()->isValueDependent()) {
5457 if (!EvaluateDependentExpr(FS->getInc(), Info))
5458 return ESR_Failed;
5459 } else {
5460 // Increment: ++__begin
5461 if (!EvaluateIgnoredValue(Info, FS->getInc()))
5462 return ESR_Failed;
5463 }
5464
5465 if (!InnerScope.destroy())
5466 return ESR_Failed;
5467 }
5468
5469 return Scope.destroy() ? ESR_Succeeded : ESR_Failed;
5470 }
5471
5472 case Stmt::SwitchStmtClass:
5473 return EvaluateSwitch(Result, Info, cast<SwitchStmt>(S));
5474
5475 case Stmt::ContinueStmtClass:
5476 return ESR_Continue;
5477
5478 case Stmt::BreakStmtClass:
5479 return ESR_Break;
5480
5481 case Stmt::LabelStmtClass:
5482 return EvaluateStmt(Result, Info, cast<LabelStmt>(S)->getSubStmt(), Case);
5483
5484 case Stmt::AttributedStmtClass:
5485 // As a general principle, C++11 attributes can be ignored without
5486 // any semantic impact.
5487 return EvaluateStmt(Result, Info, cast<AttributedStmt>(S)->getSubStmt(),
5488 Case);
5489
5490 case Stmt::CaseStmtClass:
5491 case Stmt::DefaultStmtClass:
5492 return EvaluateStmt(Result, Info, cast<SwitchCase>(S)->getSubStmt(), Case);
5493 case Stmt::CXXTryStmtClass:
5494 // Evaluate try blocks by evaluating all sub statements.
5495 return EvaluateStmt(Result, Info, cast<CXXTryStmt>(S)->getTryBlock(), Case);
5496 }
5497}
5498
5499/// CheckTrivialDefaultConstructor - Check whether a constructor is a trivial
5500/// default constructor. If so, we'll fold it whether or not it's marked as
5501/// constexpr. If it is marked as constexpr, we will never implicitly define it,
5502/// so we need special handling.
5503static bool CheckTrivialDefaultConstructor(EvalInfo &Info, SourceLocation Loc,
5504 const CXXConstructorDecl *CD,
5505 bool IsValueInitialization) {
5506 if (!CD->isTrivial() || !CD->isDefaultConstructor())
5507 return false;
5508
5509 // Value-initialization does not call a trivial default constructor, so such a
5510 // call is a core constant expression whether or not the constructor is
5511 // constexpr.
5512 if (!CD->isConstexpr() && !IsValueInitialization) {
5513 if (Info.getLangOpts().CPlusPlus11) {
5514 // FIXME: If DiagDecl is an implicitly-declared special member function,
5515 // we should be much more explicit about why it's not constexpr.
5516 Info.CCEDiag(Loc, diag::note_constexpr_invalid_function, 1)
5517 << /*IsConstexpr*/0 << /*IsConstructor*/1 << CD;
5518 Info.Note(CD->getLocation(), diag::note_declared_at);
5519 } else {
5520 Info.CCEDiag(Loc, diag::note_invalid_subexpr_in_const_expr);
5521 }
5522 }
5523 return true;
5524}
5525
5526/// CheckConstexprFunction - Check that a function can be called in a constant
5527/// expression.
5528static bool CheckConstexprFunction(EvalInfo &Info, SourceLocation CallLoc,
5530 const FunctionDecl *Definition,
5531 const Stmt *Body) {
5532 // Potential constant expressions can contain calls to declared, but not yet
5533 // defined, constexpr functions.
5534 if (Info.checkingPotentialConstantExpression() && !Definition &&
5535 Declaration->isConstexpr())
5536 return false;
5537
5538 // Bail out if the function declaration itself is invalid. We will
5539 // have produced a relevant diagnostic while parsing it, so just
5540 // note the problematic sub-expression.
5541 if (Declaration->isInvalidDecl()) {
5542 Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr);
5543 return false;
5544 }
5545
5546 // DR1872: An instantiated virtual constexpr function can't be called in a
5547 // constant expression (prior to C++20). We can still constant-fold such a
5548 // call.
5549 if (!Info.Ctx.getLangOpts().CPlusPlus20 && isa<CXXMethodDecl>(Declaration) &&
5550 cast<CXXMethodDecl>(Declaration)->isVirtual())
5551 Info.CCEDiag(CallLoc, diag::note_constexpr_virtual_call);
5552
5553 if (Definition && Definition->isInvalidDecl()) {
5554 Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr);
5555 return false;
5556 }
5557
5558 // Can we evaluate this function call?
5559 if (Definition && Definition->isConstexpr() && Body)
5560 return true;
5561
5562 if (Info.getLangOpts().CPlusPlus11) {
5563 const FunctionDecl *DiagDecl = Definition ? Definition : Declaration;
5564
5565 // If this function is not constexpr because it is an inherited
5566 // non-constexpr constructor, diagnose that directly.
5567 auto *CD = dyn_cast<CXXConstructorDecl>(DiagDecl);
5568 if (CD && CD->isInheritingConstructor()) {
5569 auto *Inherited = CD->getInheritedConstructor().getConstructor();
5570 if (!Inherited->isConstexpr())
5571 DiagDecl = CD = Inherited;
5572 }
5573
5574 // FIXME: If DiagDecl is an implicitly-declared special member function
5575 // or an inheriting constructor, we should be much more explicit about why
5576 // it's not constexpr.
5577 if (CD && CD->isInheritingConstructor())
5578 Info.FFDiag(CallLoc, diag::note_constexpr_invalid_inhctor, 1)
5579 << CD->getInheritedConstructor().getConstructor()->getParent();
5580 else
5581 Info.FFDiag(CallLoc, diag::note_constexpr_invalid_function, 1)
5582 << DiagDecl->isConstexpr() << (bool)CD << DiagDecl;
5583 Info.Note(DiagDecl->getLocation(), diag::note_declared_at);
5584 } else {
5585 Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr);
5586 }
5587 return false;
5588}
5589
5590namespace {
5591struct CheckDynamicTypeHandler {
5592 AccessKinds AccessKind;
5593 typedef bool result_type;
5594 bool failed() { return false; }
5595 bool found(APValue &Subobj, QualType SubobjType) { return true; }
5596 bool found(APSInt &Value, QualType SubobjType) { return true; }
5597 bool found(APFloat &Value, QualType SubobjType) { return true; }
5598};
5599} // end anonymous namespace
5600
5601/// Check that we can access the notional vptr of an object / determine its
5602/// dynamic type.
5603static bool checkDynamicType(EvalInfo &Info, const Expr *E, const LValue &This,
5604 AccessKinds AK, bool Polymorphic) {
5605 if (This.Designator.Invalid)
5606 return false;
5607
5608 CompleteObject Obj = findCompleteObject(Info, E, AK, This, QualType());
5609
5610 if (!Obj)