xref: /llvm-project/clang/lib/AST/APValue.cpp (revision 8ac137acefc01caf636db5f95eb0977c97def1ba) 
1 //===--- APValue.cpp - Union class for APFloat/APSInt/Complex -------------===//
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 APValue class.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "clang/AST/APValue.h"
14 #include "Linkage.h"
15 #include "clang/AST/ASTContext.h"
16 #include "clang/AST/CharUnits.h"
17 #include "clang/AST/DeclCXX.h"
18 #include "clang/AST/Expr.h"
19 #include "clang/AST/ExprCXX.h"
20 #include "clang/AST/Type.h"
21 #include "llvm/Support/ErrorHandling.h"
22 #include "llvm/Support/raw_ostream.h"
23 using namespace clang;
24 
25 /// The identity of a type_info object depends on the canonical unqualified
26 /// type only.
27 TypeInfoLValue::TypeInfoLValue(const Type *T)
28     : T(T->getCanonicalTypeUnqualified().getTypePtr()) {}
29 
30 void TypeInfoLValue::print(llvm::raw_ostream &Out,
31                            const PrintingPolicy &Policy) const {
32   Out << "typeid(";
33   QualType(getType(), 0).print(Out, Policy);
34   Out << ")";
35 }
36 
37 static_assert(
38     1 << llvm::PointerLikeTypeTraits<TypeInfoLValue>::NumLowBitsAvailable <=
39         alignof(Type),
40     "Type is insufficiently aligned");
41 
42 APValue::LValueBase::LValueBase(const ValueDecl *P, unsigned I, unsigned V)
43     : Ptr(P ? cast<ValueDecl>(P->getCanonicalDecl()) : nullptr), Local{I, V} {}
44 APValue::LValueBase::LValueBase(const Expr *P, unsigned I, unsigned V)
45     : Ptr(P), Local{I, V} {}
46 
47 APValue::LValueBase APValue::LValueBase::getDynamicAlloc(DynamicAllocLValue LV,
48                                                          QualType Type) {
49   LValueBase Base;
50   Base.Ptr = LV;
51   Base.DynamicAllocType = Type.getAsOpaquePtr();
52   return Base;
53 }
54 
55 APValue::LValueBase APValue::LValueBase::getTypeInfo(TypeInfoLValue LV,
56                                                      QualType TypeInfo) {
57   LValueBase Base;
58   Base.Ptr = LV;
59   Base.TypeInfoType = TypeInfo.getAsOpaquePtr();
60   return Base;
61 }
62 
63 QualType APValue::LValueBase::getType() const {
64   if (!*this) return QualType();
65   if (const ValueDecl *D = dyn_cast<const ValueDecl*>()) {
66     // FIXME: It's unclear where we're supposed to take the type from, and
67     // this actually matters for arrays of unknown bound. Eg:
68     //
69     // extern int arr[]; void f() { extern int arr[3]; };
70     // constexpr int *p = &arr[1]; // valid?
71     //
72     // For now, we take the most complete type we can find.
73     for (auto *Redecl = cast<ValueDecl>(D->getMostRecentDecl()); Redecl;
74          Redecl = cast_or_null<ValueDecl>(Redecl->getPreviousDecl())) {
75       QualType T = Redecl->getType();
76       if (!T->isIncompleteArrayType())
77         return T;
78     }
79     return D->getType();
80   }
81 
82   if (is<TypeInfoLValue>())
83     return getTypeInfoType();
84 
85   if (is<DynamicAllocLValue>())
86     return getDynamicAllocType();
87 
88   const Expr *Base = get<const Expr*>();
89 
90   // For a materialized temporary, the type of the temporary we materialized
91   // may not be the type of the expression.
92   if (const MaterializeTemporaryExpr *MTE =
93           clang::dyn_cast<MaterializeTemporaryExpr>(Base)) {
94     SmallVector<const Expr *, 2> CommaLHSs;
95     SmallVector<SubobjectAdjustment, 2> Adjustments;
96     const Expr *Temp = MTE->getSubExpr();
97     const Expr *Inner = Temp->skipRValueSubobjectAdjustments(CommaLHSs,
98                                                              Adjustments);
99     // Keep any cv-qualifiers from the reference if we generated a temporary
100     // for it directly. Otherwise use the type after adjustment.
101     if (!Adjustments.empty())
102       return Inner->getType();
103   }
104 
105   return Base->getType();
106 }
107 
108 unsigned APValue::LValueBase::getCallIndex() const {
109   return (is<TypeInfoLValue>() || is<DynamicAllocLValue>()) ? 0
110                                                             : Local.CallIndex;
111 }
112 
113 unsigned APValue::LValueBase::getVersion() const {
114   return (is<TypeInfoLValue>() || is<DynamicAllocLValue>()) ? 0 : Local.Version;
115 }
116 
117 QualType APValue::LValueBase::getTypeInfoType() const {
118   assert(is<TypeInfoLValue>() && "not a type_info lvalue");
119   return QualType::getFromOpaquePtr(TypeInfoType);
120 }
121 
122 QualType APValue::LValueBase::getDynamicAllocType() const {
123   assert(is<DynamicAllocLValue>() && "not a dynamic allocation lvalue");
124   return QualType::getFromOpaquePtr(DynamicAllocType);
125 }
126 
127 void APValue::LValueBase::Profile(llvm::FoldingSetNodeID &ID) const {
128   ID.AddPointer(Ptr.getOpaqueValue());
129   if (is<TypeInfoLValue>() || is<DynamicAllocLValue>())
130     return;
131   ID.AddInteger(Local.CallIndex);
132   ID.AddInteger(Local.Version);
133 }
134 
135 namespace clang {
136 bool operator==(const APValue::LValueBase &LHS,
137                 const APValue::LValueBase &RHS) {
138   if (LHS.Ptr != RHS.Ptr)
139     return false;
140   if (LHS.is<TypeInfoLValue>() || LHS.is<DynamicAllocLValue>())
141     return true;
142   return LHS.Local.CallIndex == RHS.Local.CallIndex &&
143          LHS.Local.Version == RHS.Local.Version;
144 }
145 }
146 
147 APValue::LValuePathEntry::LValuePathEntry(BaseOrMemberType BaseOrMember) {
148   if (const Decl *D = BaseOrMember.getPointer())
149     BaseOrMember.setPointer(D->getCanonicalDecl());
150   Value = reinterpret_cast<uintptr_t>(BaseOrMember.getOpaqueValue());
151 }
152 
153 void APValue::LValuePathEntry::Profile(llvm::FoldingSetNodeID &ID) const {
154   ID.AddInteger(Value);
155 }
156 
157 APValue::LValuePathSerializationHelper::LValuePathSerializationHelper(
158     ArrayRef<LValuePathEntry> Path, QualType ElemTy)
159     : Ty((const void *)ElemTy.getTypePtrOrNull()), Path(Path) {}
160 
161 QualType APValue::LValuePathSerializationHelper::getType() {
162   return QualType::getFromOpaquePtr(Ty);
163 }
164 
165 namespace {
166   struct LVBase {
167     APValue::LValueBase Base;
168     CharUnits Offset;
169     unsigned PathLength;
170     bool IsNullPtr : 1;
171     bool IsOnePastTheEnd : 1;
172   };
173 }
174 
175 void *APValue::LValueBase::getOpaqueValue() const {
176   return Ptr.getOpaqueValue();
177 }
178 
179 bool APValue::LValueBase::isNull() const {
180   return Ptr.isNull();
181 }
182 
183 APValue::LValueBase::operator bool () const {
184   return static_cast<bool>(Ptr);
185 }
186 
187 clang::APValue::LValueBase
188 llvm::DenseMapInfo<clang::APValue::LValueBase>::getEmptyKey() {
189   clang::APValue::LValueBase B;
190   B.Ptr = DenseMapInfo<const ValueDecl*>::getEmptyKey();
191   return B;
192 }
193 
194 clang::APValue::LValueBase
195 llvm::DenseMapInfo<clang::APValue::LValueBase>::getTombstoneKey() {
196   clang::APValue::LValueBase B;
197   B.Ptr = DenseMapInfo<const ValueDecl*>::getTombstoneKey();
198   return B;
199 }
200 
201 namespace clang {
202 llvm::hash_code hash_value(const APValue::LValueBase &Base) {
203   if (Base.is<TypeInfoLValue>() || Base.is<DynamicAllocLValue>())
204     return llvm::hash_value(Base.getOpaqueValue());
205   return llvm::hash_combine(Base.getOpaqueValue(), Base.getCallIndex(),
206                             Base.getVersion());
207 }
208 }
209 
210 unsigned llvm::DenseMapInfo<clang::APValue::LValueBase>::getHashValue(
211     const clang::APValue::LValueBase &Base) {
212   return hash_value(Base);
213 }
214 
215 bool llvm::DenseMapInfo<clang::APValue::LValueBase>::isEqual(
216     const clang::APValue::LValueBase &LHS,
217     const clang::APValue::LValueBase &RHS) {
218   return LHS == RHS;
219 }
220 
221 struct APValue::LV : LVBase {
222   static const unsigned InlinePathSpace =
223       (DataSize - sizeof(LVBase)) / sizeof(LValuePathEntry);
224 
225   /// Path - The sequence of base classes, fields and array indices to follow to
226   /// walk from Base to the subobject. When performing GCC-style folding, there
227   /// may not be such a path.
228   union {
229     LValuePathEntry Path[InlinePathSpace];
230     LValuePathEntry *PathPtr;
231   };
232 
233   LV() { PathLength = (unsigned)-1; }
234   ~LV() { resizePath(0); }
235 
236   void resizePath(unsigned Length) {
237     if (Length == PathLength)
238       return;
239     if (hasPathPtr())
240       delete [] PathPtr;
241     PathLength = Length;
242     if (hasPathPtr())
243       PathPtr = new LValuePathEntry[Length];
244   }
245 
246   bool hasPath() const { return PathLength != (unsigned)-1; }
247   bool hasPathPtr() const { return hasPath() && PathLength > InlinePathSpace; }
248 
249   LValuePathEntry *getPath() { return hasPathPtr() ? PathPtr : Path; }
250   const LValuePathEntry *getPath() const {
251     return hasPathPtr() ? PathPtr : Path;
252   }
253 };
254 
255 namespace {
256   struct MemberPointerBase {
257     llvm::PointerIntPair<const ValueDecl*, 1, bool> MemberAndIsDerivedMember;
258     unsigned PathLength;
259   };
260 }
261 
262 struct APValue::MemberPointerData : MemberPointerBase {
263   static const unsigned InlinePathSpace =
264       (DataSize - sizeof(MemberPointerBase)) / sizeof(const CXXRecordDecl*);
265   typedef const CXXRecordDecl *PathElem;
266   union {
267     PathElem Path[InlinePathSpace];
268     PathElem *PathPtr;
269   };
270 
271   MemberPointerData() { PathLength = 0; }
272   ~MemberPointerData() { resizePath(0); }
273 
274   void resizePath(unsigned Length) {
275     if (Length == PathLength)
276       return;
277     if (hasPathPtr())
278       delete [] PathPtr;
279     PathLength = Length;
280     if (hasPathPtr())
281       PathPtr = new PathElem[Length];
282   }
283 
284   bool hasPathPtr() const { return PathLength > InlinePathSpace; }
285 
286   PathElem *getPath() { return hasPathPtr() ? PathPtr : Path; }
287   const PathElem *getPath() const {
288     return hasPathPtr() ? PathPtr : Path;
289   }
290 };
291 
292 // FIXME: Reduce the malloc traffic here.
293 
294 APValue::Arr::Arr(unsigned NumElts, unsigned Size) :
295   Elts(new APValue[NumElts + (NumElts != Size ? 1 : 0)]),
296   NumElts(NumElts), ArrSize(Size) {}
297 APValue::Arr::~Arr() { delete [] Elts; }
298 
299 APValue::StructData::StructData(unsigned NumBases, unsigned NumFields) :
300   Elts(new APValue[NumBases+NumFields]),
301   NumBases(NumBases), NumFields(NumFields) {}
302 APValue::StructData::~StructData() {
303   delete [] Elts;
304 }
305 
306 APValue::UnionData::UnionData() : Field(nullptr), Value(new APValue) {}
307 APValue::UnionData::~UnionData () {
308   delete Value;
309 }
310 
311 APValue::APValue(const APValue &RHS) : Kind(None) {
312   switch (RHS.getKind()) {
313   case None:
314   case Indeterminate:
315     Kind = RHS.getKind();
316     break;
317   case Int:
318     MakeInt();
319     setInt(RHS.getInt());
320     break;
321   case Float:
322     MakeFloat();
323     setFloat(RHS.getFloat());
324     break;
325   case FixedPoint: {
326     APFixedPoint FXCopy = RHS.getFixedPoint();
327     MakeFixedPoint(std::move(FXCopy));
328     break;
329   }
330   case Vector:
331     MakeVector();
332     setVector(((const Vec *)(const char *)&RHS.Data)->Elts,
333               RHS.getVectorLength());
334     break;
335   case ComplexInt:
336     MakeComplexInt();
337     setComplexInt(RHS.getComplexIntReal(), RHS.getComplexIntImag());
338     break;
339   case ComplexFloat:
340     MakeComplexFloat();
341     setComplexFloat(RHS.getComplexFloatReal(), RHS.getComplexFloatImag());
342     break;
343   case LValue:
344     MakeLValue();
345     if (RHS.hasLValuePath())
346       setLValue(RHS.getLValueBase(), RHS.getLValueOffset(), RHS.getLValuePath(),
347                 RHS.isLValueOnePastTheEnd(), RHS.isNullPointer());
348     else
349       setLValue(RHS.getLValueBase(), RHS.getLValueOffset(), NoLValuePath(),
350                 RHS.isNullPointer());
351     break;
352   case Array:
353     MakeArray(RHS.getArrayInitializedElts(), RHS.getArraySize());
354     for (unsigned I = 0, N = RHS.getArrayInitializedElts(); I != N; ++I)
355       getArrayInitializedElt(I) = RHS.getArrayInitializedElt(I);
356     if (RHS.hasArrayFiller())
357       getArrayFiller() = RHS.getArrayFiller();
358     break;
359   case Struct:
360     MakeStruct(RHS.getStructNumBases(), RHS.getStructNumFields());
361     for (unsigned I = 0, N = RHS.getStructNumBases(); I != N; ++I)
362       getStructBase(I) = RHS.getStructBase(I);
363     for (unsigned I = 0, N = RHS.getStructNumFields(); I != N; ++I)
364       getStructField(I) = RHS.getStructField(I);
365     break;
366   case Union:
367     MakeUnion();
368     setUnion(RHS.getUnionField(), RHS.getUnionValue());
369     break;
370   case MemberPointer:
371     MakeMemberPointer(RHS.getMemberPointerDecl(),
372                       RHS.isMemberPointerToDerivedMember(),
373                       RHS.getMemberPointerPath());
374     break;
375   case AddrLabelDiff:
376     MakeAddrLabelDiff();
377     setAddrLabelDiff(RHS.getAddrLabelDiffLHS(), RHS.getAddrLabelDiffRHS());
378     break;
379   }
380 }
381 
382 APValue::APValue(APValue &&RHS) : Kind(RHS.Kind), Data(RHS.Data) {
383   RHS.Kind = None;
384 }
385 
386 APValue &APValue::operator=(const APValue &RHS) {
387   if (this != &RHS)
388     *this = APValue(RHS);
389   return *this;
390 }
391 
392 APValue &APValue::operator=(APValue &&RHS) {
393   if (this != RHS) {
394     if (Kind != None && Kind != Indeterminate)
395       DestroyDataAndMakeUninit();
396     Kind = RHS.Kind;
397     Data = RHS.Data;
398     RHS.Kind = None;
399   }
400   return *this;
401 }
402 
403 void APValue::DestroyDataAndMakeUninit() {
404   if (Kind == Int)
405     ((APSInt *)(char *)&Data)->~APSInt();
406   else if (Kind == Float)
407     ((APFloat *)(char *)&Data)->~APFloat();
408   else if (Kind == FixedPoint)
409     ((APFixedPoint *)(char *)&Data)->~APFixedPoint();
410   else if (Kind == Vector)
411     ((Vec *)(char *)&Data)->~Vec();
412   else if (Kind == ComplexInt)
413     ((ComplexAPSInt *)(char *)&Data)->~ComplexAPSInt();
414   else if (Kind == ComplexFloat)
415     ((ComplexAPFloat *)(char *)&Data)->~ComplexAPFloat();
416   else if (Kind == LValue)
417     ((LV *)(char *)&Data)->~LV();
418   else if (Kind == Array)
419     ((Arr *)(char *)&Data)->~Arr();
420   else if (Kind == Struct)
421     ((StructData *)(char *)&Data)->~StructData();
422   else if (Kind == Union)
423     ((UnionData *)(char *)&Data)->~UnionData();
424   else if (Kind == MemberPointer)
425     ((MemberPointerData *)(char *)&Data)->~MemberPointerData();
426   else if (Kind == AddrLabelDiff)
427     ((AddrLabelDiffData *)(char *)&Data)->~AddrLabelDiffData();
428   Kind = None;
429 }
430 
431 bool APValue::needsCleanup() const {
432   switch (getKind()) {
433   case None:
434   case Indeterminate:
435   case AddrLabelDiff:
436     return false;
437   case Struct:
438   case Union:
439   case Array:
440   case Vector:
441     return true;
442   case Int:
443     return getInt().needsCleanup();
444   case Float:
445     return getFloat().needsCleanup();
446   case FixedPoint:
447     return getFixedPoint().getValue().needsCleanup();
448   case ComplexFloat:
449     assert(getComplexFloatImag().needsCleanup() ==
450                getComplexFloatReal().needsCleanup() &&
451            "In _Complex float types, real and imaginary values always have the "
452            "same size.");
453     return getComplexFloatReal().needsCleanup();
454   case ComplexInt:
455     assert(getComplexIntImag().needsCleanup() ==
456                getComplexIntReal().needsCleanup() &&
457            "In _Complex int types, real and imaginary values must have the "
458            "same size.");
459     return getComplexIntReal().needsCleanup();
460   case LValue:
461     return reinterpret_cast<const LV *>(&Data)->hasPathPtr();
462   case MemberPointer:
463     return reinterpret_cast<const MemberPointerData *>(&Data)->hasPathPtr();
464   }
465   llvm_unreachable("Unknown APValue kind!");
466 }
467 
468 void APValue::swap(APValue &RHS) {
469   std::swap(Kind, RHS.Kind);
470   std::swap(Data, RHS.Data);
471 }
472 
473 /// Profile the value of an APInt, excluding its bit-width.
474 static void profileIntValue(llvm::FoldingSetNodeID &ID, const llvm::APInt &V) {
475   for (unsigned I = 0, N = V.getBitWidth(); I < N; I += 32)
476     ID.AddInteger((uint32_t)V.extractBitsAsZExtValue(std::min(32u, N - I), I));
477 }
478 
479 void APValue::Profile(llvm::FoldingSetNodeID &ID) const {
480   // Note that our profiling assumes that only APValues of the same type are
481   // ever compared. As a result, we don't consider collisions that could only
482   // happen if the types are different. (For example, structs with different
483   // numbers of members could profile the same.)
484 
485   ID.AddInteger(Kind);
486 
487   switch (Kind) {
488   case None:
489   case Indeterminate:
490     return;
491 
492   case AddrLabelDiff:
493     ID.AddPointer(getAddrLabelDiffLHS()->getLabel()->getCanonicalDecl());
494     ID.AddPointer(getAddrLabelDiffRHS()->getLabel()->getCanonicalDecl());
495     return;
496 
497   case Struct:
498     for (unsigned I = 0, N = getStructNumBases(); I != N; ++I)
499       getStructBase(I).Profile(ID);
500     for (unsigned I = 0, N = getStructNumFields(); I != N; ++I)
501       getStructField(I).Profile(ID);
502     return;
503 
504   case Union:
505     if (!getUnionField()) {
506       ID.AddInteger(0);
507       return;
508     }
509     ID.AddInteger(getUnionField()->getFieldIndex() + 1);
510     getUnionValue().Profile(ID);
511     return;
512 
513   case Array: {
514     if (getArraySize() == 0)
515       return;
516 
517     // The profile should not depend on whether the array is expanded or
518     // not, but we don't want to profile the array filler many times for
519     // a large array. So treat all equal trailing elements as the filler.
520     // Elements are profiled in reverse order to support this, and the
521     // first profiled element is followed by a count. For example:
522     //
523     //   ['a', 'c', 'x', 'x', 'x'] is profiled as
524     //   [5, 'x', 3, 'c', 'a']
525     llvm::FoldingSetNodeID FillerID;
526     (hasArrayFiller() ? getArrayFiller()
527                       : getArrayInitializedElt(getArrayInitializedElts() - 1))
528         .Profile(FillerID);
529     ID.AddNodeID(FillerID);
530     unsigned NumFillers = getArraySize() - getArrayInitializedElts();
531     unsigned N = getArrayInitializedElts();
532 
533     // Count the number of elements equal to the last one. This loop ends
534     // by adding an integer indicating the number of such elements, with
535     // N set to the number of elements left to profile.
536     while (true) {
537       if (N == 0) {
538         // All elements are fillers.
539         assert(NumFillers == getArraySize());
540         ID.AddInteger(NumFillers);
541         break;
542       }
543 
544       // No need to check if the last element is equal to the last
545       // element.
546       if (N != getArraySize()) {
547         llvm::FoldingSetNodeID ElemID;
548         getArrayInitializedElt(N - 1).Profile(ElemID);
549         if (ElemID != FillerID) {
550           ID.AddInteger(NumFillers);
551           ID.AddNodeID(ElemID);
552           --N;
553           break;
554         }
555       }
556 
557       // This is a filler.
558       ++NumFillers;
559       --N;
560     }
561 
562     // Emit the remaining elements.
563     for (; N != 0; --N)
564       getArrayInitializedElt(N - 1).Profile(ID);
565     return;
566   }
567 
568   case Vector:
569     for (unsigned I = 0, N = getVectorLength(); I != N; ++I)
570       getVectorElt(I).Profile(ID);
571     return;
572 
573   case Int:
574     profileIntValue(ID, getInt());
575     return;
576 
577   case Float:
578     profileIntValue(ID, getFloat().bitcastToAPInt());
579     return;
580 
581   case FixedPoint:
582     profileIntValue(ID, getFixedPoint().getValue());
583     return;
584 
585   case ComplexFloat:
586     profileIntValue(ID, getComplexFloatReal().bitcastToAPInt());
587     profileIntValue(ID, getComplexFloatImag().bitcastToAPInt());
588     return;
589 
590   case ComplexInt:
591     profileIntValue(ID, getComplexIntReal());
592     profileIntValue(ID, getComplexIntImag());
593     return;
594 
595   case LValue:
596     getLValueBase().Profile(ID);
597     ID.AddInteger(getLValueOffset().getQuantity());
598     ID.AddInteger((isNullPointer() ? 1 : 0) |
599                   (isLValueOnePastTheEnd() ? 2 : 0) |
600                   (hasLValuePath() ? 4 : 0));
601     if (hasLValuePath()) {
602       ID.AddInteger(getLValuePath().size());
603       // For uniqueness, we only need to profile the entries corresponding
604       // to union members, but we don't have the type here so we don't know
605       // how to interpret the entries.
606       for (LValuePathEntry E : getLValuePath())
607         E.Profile(ID);
608     }
609     return;
610 
611   case MemberPointer:
612     ID.AddPointer(getMemberPointerDecl());
613     ID.AddInteger(isMemberPointerToDerivedMember());
614     for (const CXXRecordDecl *D : getMemberPointerPath())
615       ID.AddPointer(D);
616     return;
617   }
618 
619   llvm_unreachable("Unknown APValue kind!");
620 }
621 
622 static double GetApproxValue(const llvm::APFloat &F) {
623   llvm::APFloat V = F;
624   bool ignored;
625   V.convert(llvm::APFloat::IEEEdouble(), llvm::APFloat::rmNearestTiesToEven,
626             &ignored);
627   return V.convertToDouble();
628 }
629 
630 static bool TryPrintAsStringLiteral(raw_ostream &Out,
631                                     const PrintingPolicy &Policy,
632                                     const ArrayType *ATy,
633                                     ArrayRef<APValue> Inits) {
634   if (Inits.empty())
635     return false;
636 
637   QualType Ty = ATy->getElementType();
638   if (!Ty->isAnyCharacterType())
639     return false;
640 
641   // Nothing we can do about a sequence that is not null-terminated
642   if (!Inits.back().isInt() || !Inits.back().getInt().isZero())
643     return false;
644 
645   Inits = Inits.drop_back();
646 
647   llvm::SmallString<40> Buf;
648   Buf.push_back('"');
649 
650   // Better than printing a two-digit sequence of 10 integers.
651   constexpr size_t MaxN = 36;
652   StringRef Ellipsis;
653   if (Inits.size() > MaxN && !Policy.EntireContentsOfLargeArray) {
654     Ellipsis = "[...]";
655     Inits =
656         Inits.take_front(std::min(MaxN - Ellipsis.size() / 2, Inits.size()));
657   }
658 
659   for (auto &Val : Inits) {
660     if (!Val.isInt())
661       return false;
662     int64_t Char64 = Val.getInt().getExtValue();
663     if (!isASCII(Char64))
664       return false; // Bye bye, see you in integers.
665     auto Ch = static_cast<unsigned char>(Char64);
666     // The diagnostic message is 'quoted'
667     StringRef Escaped = escapeCStyle<EscapeChar::SingleAndDouble>(Ch);
668     if (Escaped.empty()) {
669       if (!isPrintable(Ch))
670         return false;
671       Buf.emplace_back(Ch);
672     } else {
673       Buf.append(Escaped);
674     }
675   }
676 
677   Buf.append(Ellipsis);
678   Buf.push_back('"');
679 
680   if (Ty->isWideCharType())
681     Out << 'L';
682   else if (Ty->isChar8Type())
683     Out << "u8";
684   else if (Ty->isChar16Type())
685     Out << 'u';
686   else if (Ty->isChar32Type())
687     Out << 'U';
688 
689   Out << Buf;
690   return true;
691 }
692 
693 void APValue::printPretty(raw_ostream &Out, const ASTContext &Ctx,
694                           QualType Ty) const {
695   printPretty(Out, Ctx.getPrintingPolicy(), Ty, &Ctx);
696 }
697 
698 void APValue::printPretty(raw_ostream &Out, const PrintingPolicy &Policy,
699                           QualType Ty, const ASTContext *Ctx) const {
700   // There are no objects of type 'void', but values of this type can be
701   // returned from functions.
702   if (Ty->isVoidType()) {
703     Out << "void()";
704     return;
705   }
706 
707   switch (getKind()) {
708   case APValue::None:
709     Out << "<out of lifetime>";
710     return;
711   case APValue::Indeterminate:
712     Out << "<uninitialized>";
713     return;
714   case APValue::Int:
715     if (Ty->isBooleanType())
716       Out << (getInt().getBoolValue() ? "true" : "false");
717     else
718       Out << getInt();
719     return;
720   case APValue::Float:
721     Out << GetApproxValue(getFloat());
722     return;
723   case APValue::FixedPoint:
724     Out << getFixedPoint();
725     return;
726   case APValue::Vector: {
727     Out << '{';
728     QualType ElemTy = Ty->castAs<VectorType>()->getElementType();
729     getVectorElt(0).printPretty(Out, Policy, ElemTy, Ctx);
730     for (unsigned i = 1; i != getVectorLength(); ++i) {
731       Out << ", ";
732       getVectorElt(i).printPretty(Out, Policy, ElemTy, Ctx);
733     }
734     Out << '}';
735     return;
736   }
737   case APValue::ComplexInt:
738     Out << getComplexIntReal() << "+" << getComplexIntImag() << "i";
739     return;
740   case APValue::ComplexFloat:
741     Out << GetApproxValue(getComplexFloatReal()) << "+"
742         << GetApproxValue(getComplexFloatImag()) << "i";
743     return;
744   case APValue::LValue: {
745     bool IsReference = Ty->isReferenceType();
746     QualType InnerTy
747       = IsReference ? Ty.getNonReferenceType() : Ty->getPointeeType();
748     if (InnerTy.isNull())
749       InnerTy = Ty;
750 
751     LValueBase Base = getLValueBase();
752     if (!Base) {
753       if (isNullPointer()) {
754         Out << (Policy.Nullptr ? "nullptr" : "0");
755       } else if (IsReference) {
756         Out << "*(" << InnerTy.stream(Policy) << "*)"
757             << getLValueOffset().getQuantity();
758       } else {
759         Out << "(" << Ty.stream(Policy) << ")"
760             << getLValueOffset().getQuantity();
761       }
762       return;
763     }
764 
765     if (!hasLValuePath()) {
766       // No lvalue path: just print the offset.
767       CharUnits O = getLValueOffset();
768       CharUnits S = Ctx ? Ctx->getTypeSizeInCharsIfKnown(InnerTy).value_or(
769                               CharUnits::Zero())
770                         : CharUnits::Zero();
771       if (!O.isZero()) {
772         if (IsReference)
773           Out << "*(";
774         if (S.isZero() || O % S) {
775           Out << "(char*)";
776           S = CharUnits::One();
777         }
778         Out << '&';
779       } else if (!IsReference) {
780         Out << '&';
781       }
782 
783       if (const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>())
784         Out << *VD;
785       else if (TypeInfoLValue TI = Base.dyn_cast<TypeInfoLValue>()) {
786         TI.print(Out, Policy);
787       } else if (DynamicAllocLValue DA = Base.dyn_cast<DynamicAllocLValue>()) {
788         Out << "{*new "
789             << Base.getDynamicAllocType().stream(Policy) << "#"
790             << DA.getIndex() << "}";
791       } else {
792         assert(Base.get<const Expr *>() != nullptr &&
793                "Expecting non-null Expr");
794         Base.get<const Expr*>()->printPretty(Out, nullptr, Policy);
795       }
796 
797       if (!O.isZero()) {
798         Out << " + " << (O / S);
799         if (IsReference)
800           Out << ')';
801       }
802       return;
803     }
804 
805     // We have an lvalue path. Print it out nicely.
806     if (!IsReference)
807       Out << '&';
808     else if (isLValueOnePastTheEnd())
809       Out << "*(&";
810 
811     QualType ElemTy = Base.getType();
812     if (const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>()) {
813       Out << *VD;
814     } else if (TypeInfoLValue TI = Base.dyn_cast<TypeInfoLValue>()) {
815       TI.print(Out, Policy);
816     } else if (DynamicAllocLValue DA = Base.dyn_cast<DynamicAllocLValue>()) {
817       Out << "{*new " << Base.getDynamicAllocType().stream(Policy) << "#"
818           << DA.getIndex() << "}";
819     } else {
820       const Expr *E = Base.get<const Expr*>();
821       assert(E != nullptr && "Expecting non-null Expr");
822       E->printPretty(Out, nullptr, Policy);
823     }
824 
825     ArrayRef<LValuePathEntry> Path = getLValuePath();
826     const CXXRecordDecl *CastToBase = nullptr;
827     for (unsigned I = 0, N = Path.size(); I != N; ++I) {
828       if (ElemTy->isRecordType()) {
829         // The lvalue refers to a class type, so the next path entry is a base
830         // or member.
831         const Decl *BaseOrMember = Path[I].getAsBaseOrMember().getPointer();
832         if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(BaseOrMember)) {
833           CastToBase = RD;
834           // Leave ElemTy referring to the most-derived class. The actual type
835           // doesn't matter except for array types.
836         } else {
837           const ValueDecl *VD = cast<ValueDecl>(BaseOrMember);
838           Out << ".";
839           if (CastToBase)
840             Out << *CastToBase << "::";
841           Out << *VD;
842           ElemTy = VD->getType();
843         }
844       } else {
845         // The lvalue must refer to an array.
846         Out << '[' << Path[I].getAsArrayIndex() << ']';
847         ElemTy = ElemTy->castAsArrayTypeUnsafe()->getElementType();
848       }
849     }
850 
851     // Handle formatting of one-past-the-end lvalues.
852     if (isLValueOnePastTheEnd()) {
853       // FIXME: If CastToBase is non-0, we should prefix the output with
854       // "(CastToBase*)".
855       Out << " + 1";
856       if (IsReference)
857         Out << ')';
858     }
859     return;
860   }
861   case APValue::Array: {
862     const ArrayType *AT = Ty->castAsArrayTypeUnsafe();
863     unsigned N = getArrayInitializedElts();
864     if (N != 0 && TryPrintAsStringLiteral(Out, Policy, AT,
865                                           {&getArrayInitializedElt(0), N}))
866       return;
867     QualType ElemTy = AT->getElementType();
868     Out << '{';
869     unsigned I = 0;
870     switch (N) {
871     case 0:
872       for (; I != N; ++I) {
873         Out << ", ";
874         if (I == 10 && !Policy.EntireContentsOfLargeArray) {
875           Out << "...}";
876           return;
877         }
878         [[fallthrough]];
879       default:
880         getArrayInitializedElt(I).printPretty(Out, Policy, ElemTy, Ctx);
881       }
882     }
883     Out << '}';
884     return;
885   }
886   case APValue::Struct: {
887     Out << '{';
888     const RecordDecl *RD = Ty->castAs<RecordType>()->getDecl();
889     bool First = true;
890     if (unsigned N = getStructNumBases()) {
891       const CXXRecordDecl *CD = cast<CXXRecordDecl>(RD);
892       CXXRecordDecl::base_class_const_iterator BI = CD->bases_begin();
893       for (unsigned I = 0; I != N; ++I, ++BI) {
894         assert(BI != CD->bases_end());
895         if (!First)
896           Out << ", ";
897         getStructBase(I).printPretty(Out, Policy, BI->getType(), Ctx);
898         First = false;
899       }
900     }
901     for (const auto *FI : RD->fields()) {
902       if (!First)
903         Out << ", ";
904       if (FI->isUnnamedBitfield()) continue;
905       getStructField(FI->getFieldIndex()).
906         printPretty(Out, Policy, FI->getType(), Ctx);
907       First = false;
908     }
909     Out << '}';
910     return;
911   }
912   case APValue::Union:
913     Out << '{';
914     if (const FieldDecl *FD = getUnionField()) {
915       Out << "." << *FD << " = ";
916       getUnionValue().printPretty(Out, Policy, FD->getType(), Ctx);
917     }
918     Out << '}';
919     return;
920   case APValue::MemberPointer:
921     // FIXME: This is not enough to unambiguously identify the member in a
922     // multiple-inheritance scenario.
923     if (const ValueDecl *VD = getMemberPointerDecl()) {
924       Out << '&' << *cast<CXXRecordDecl>(VD->getDeclContext()) << "::" << *VD;
925       return;
926     }
927     Out << "0";
928     return;
929   case APValue::AddrLabelDiff:
930     Out << "&&" << getAddrLabelDiffLHS()->getLabel()->getName();
931     Out << " - ";
932     Out << "&&" << getAddrLabelDiffRHS()->getLabel()->getName();
933     return;
934   }
935   llvm_unreachable("Unknown APValue kind!");
936 }
937 
938 std::string APValue::getAsString(const ASTContext &Ctx, QualType Ty) const {
939   std::string Result;
940   llvm::raw_string_ostream Out(Result);
941   printPretty(Out, Ctx, Ty);
942   Out.flush();
943   return Result;
944 }
945 
946 bool APValue::toIntegralConstant(APSInt &Result, QualType SrcTy,
947                                  const ASTContext &Ctx) const {
948   if (isInt()) {
949     Result = getInt();
950     return true;
951   }
952 
953   if (isLValue() && isNullPointer()) {
954     Result = Ctx.MakeIntValue(Ctx.getTargetNullPointerValue(SrcTy), SrcTy);
955     return true;
956   }
957 
958   if (isLValue() && !getLValueBase()) {
959     Result = Ctx.MakeIntValue(getLValueOffset().getQuantity(), SrcTy);
960     return true;
961   }
962 
963   return false;
964 }
965 
966 const APValue::LValueBase APValue::getLValueBase() const {
967   assert(isLValue() && "Invalid accessor");
968   return ((const LV *)(const void *)&Data)->Base;
969 }
970 
971 bool APValue::isLValueOnePastTheEnd() const {
972   assert(isLValue() && "Invalid accessor");
973   return ((const LV *)(const void *)&Data)->IsOnePastTheEnd;
974 }
975 
976 CharUnits &APValue::getLValueOffset() {
977   assert(isLValue() && "Invalid accessor");
978   return ((LV *)(void *)&Data)->Offset;
979 }
980 
981 bool APValue::hasLValuePath() const {
982   assert(isLValue() && "Invalid accessor");
983   return ((const LV *)(const char *)&Data)->hasPath();
984 }
985 
986 ArrayRef<APValue::LValuePathEntry> APValue::getLValuePath() const {
987   assert(isLValue() && hasLValuePath() && "Invalid accessor");
988   const LV &LVal = *((const LV *)(const char *)&Data);
989   return llvm::ArrayRef(LVal.getPath(), LVal.PathLength);
990 }
991 
992 unsigned APValue::getLValueCallIndex() const {
993   assert(isLValue() && "Invalid accessor");
994   return ((const LV *)(const char *)&Data)->Base.getCallIndex();
995 }
996 
997 unsigned APValue::getLValueVersion() const {
998   assert(isLValue() && "Invalid accessor");
999   return ((const LV *)(const char *)&Data)->Base.getVersion();
1000 }
1001 
1002 bool APValue::isNullPointer() const {
1003   assert(isLValue() && "Invalid usage");
1004   return ((const LV *)(const char *)&Data)->IsNullPtr;
1005 }
1006 
1007 void APValue::setLValue(LValueBase B, const CharUnits &O, NoLValuePath,
1008                         bool IsNullPtr) {
1009   assert(isLValue() && "Invalid accessor");
1010   LV &LVal = *((LV *)(char *)&Data);
1011   LVal.Base = B;
1012   LVal.IsOnePastTheEnd = false;
1013   LVal.Offset = O;
1014   LVal.resizePath((unsigned)-1);
1015   LVal.IsNullPtr = IsNullPtr;
1016 }
1017 
1018 MutableArrayRef<APValue::LValuePathEntry>
1019 APValue::setLValueUninit(LValueBase B, const CharUnits &O, unsigned Size,
1020                          bool IsOnePastTheEnd, bool IsNullPtr) {
1021   assert(isLValue() && "Invalid accessor");
1022   LV &LVal = *((LV *)(char *)&Data);
1023   LVal.Base = B;
1024   LVal.IsOnePastTheEnd = IsOnePastTheEnd;
1025   LVal.Offset = O;
1026   LVal.IsNullPtr = IsNullPtr;
1027   LVal.resizePath(Size);
1028   return {LVal.getPath(), Size};
1029 }
1030 
1031 void APValue::setLValue(LValueBase B, const CharUnits &O,
1032                         ArrayRef<LValuePathEntry> Path, bool IsOnePastTheEnd,
1033                         bool IsNullPtr) {
1034   MutableArrayRef<APValue::LValuePathEntry> InternalPath =
1035       setLValueUninit(B, O, Path.size(), IsOnePastTheEnd, IsNullPtr);
1036   if (Path.size()) {
1037     memcpy(InternalPath.data(), Path.data(),
1038            Path.size() * sizeof(LValuePathEntry));
1039   }
1040 }
1041 
1042 void APValue::setUnion(const FieldDecl *Field, const APValue &Value) {
1043   assert(isUnion() && "Invalid accessor");
1044   ((UnionData *)(char *)&Data)->Field =
1045       Field ? Field->getCanonicalDecl() : nullptr;
1046   *((UnionData *)(char *)&Data)->Value = Value;
1047 }
1048 
1049 const ValueDecl *APValue::getMemberPointerDecl() const {
1050   assert(isMemberPointer() && "Invalid accessor");
1051   const MemberPointerData &MPD =
1052       *((const MemberPointerData *)(const char *)&Data);
1053   return MPD.MemberAndIsDerivedMember.getPointer();
1054 }
1055 
1056 bool APValue::isMemberPointerToDerivedMember() const {
1057   assert(isMemberPointer() && "Invalid accessor");
1058   const MemberPointerData &MPD =
1059       *((const MemberPointerData *)(const char *)&Data);
1060   return MPD.MemberAndIsDerivedMember.getInt();
1061 }
1062 
1063 ArrayRef<const CXXRecordDecl*> APValue::getMemberPointerPath() const {
1064   assert(isMemberPointer() && "Invalid accessor");
1065   const MemberPointerData &MPD =
1066       *((const MemberPointerData *)(const char *)&Data);
1067   return llvm::ArrayRef(MPD.getPath(), MPD.PathLength);
1068 }
1069 
1070 void APValue::MakeLValue() {
1071   assert(isAbsent() && "Bad state change");
1072   static_assert(sizeof(LV) <= DataSize, "LV too big");
1073   new ((void *)(char *)&Data) LV();
1074   Kind = LValue;
1075 }
1076 
1077 void APValue::MakeArray(unsigned InitElts, unsigned Size) {
1078   assert(isAbsent() && "Bad state change");
1079   new ((void *)(char *)&Data) Arr(InitElts, Size);
1080   Kind = Array;
1081 }
1082 
1083 MutableArrayRef<APValue::LValuePathEntry>
1084 setLValueUninit(APValue::LValueBase B, const CharUnits &O, unsigned Size,
1085                 bool OnePastTheEnd, bool IsNullPtr);
1086 
1087 MutableArrayRef<const CXXRecordDecl *>
1088 APValue::setMemberPointerUninit(const ValueDecl *Member, bool IsDerivedMember,
1089                                 unsigned Size) {
1090   assert(isAbsent() && "Bad state change");
1091   MemberPointerData *MPD = new ((void *)(char *)&Data) MemberPointerData;
1092   Kind = MemberPointer;
1093   MPD->MemberAndIsDerivedMember.setPointer(
1094       Member ? cast<ValueDecl>(Member->getCanonicalDecl()) : nullptr);
1095   MPD->MemberAndIsDerivedMember.setInt(IsDerivedMember);
1096   MPD->resizePath(Size);
1097   return {MPD->getPath(), MPD->PathLength};
1098 }
1099 
1100 void APValue::MakeMemberPointer(const ValueDecl *Member, bool IsDerivedMember,
1101                                 ArrayRef<const CXXRecordDecl *> Path) {
1102   MutableArrayRef<const CXXRecordDecl *> InternalPath =
1103       setMemberPointerUninit(Member, IsDerivedMember, Path.size());
1104   for (unsigned I = 0; I != Path.size(); ++I)
1105     InternalPath[I] = Path[I]->getCanonicalDecl();
1106 }
1107 
1108 LinkageInfo LinkageComputer::getLVForValue(const APValue &V,
1109                                            LVComputationKind computation) {
1110   LinkageInfo LV = LinkageInfo::external();
1111 
1112   auto MergeLV = [&](LinkageInfo MergeLV) {
1113     LV.merge(MergeLV);
1114     return LV.getLinkage() == InternalLinkage;
1115   };
1116   auto Merge = [&](const APValue &V) {
1117     return MergeLV(getLVForValue(V, computation));
1118   };
1119 
1120   switch (V.getKind()) {
1121   case APValue::None:
1122   case APValue::Indeterminate:
1123   case APValue::Int:
1124   case APValue::Float:
1125   case APValue::FixedPoint:
1126   case APValue::ComplexInt:
1127   case APValue::ComplexFloat:
1128   case APValue::Vector:
1129     break;
1130 
1131   case APValue::AddrLabelDiff:
1132     // Even for an inline function, it's not reasonable to treat a difference
1133     // between the addresses of labels as an external value.
1134     return LinkageInfo::internal();
1135 
1136   case APValue::Struct: {
1137     for (unsigned I = 0, N = V.getStructNumBases(); I != N; ++I)
1138       if (Merge(V.getStructBase(I)))
1139         break;
1140     for (unsigned I = 0, N = V.getStructNumFields(); I != N; ++I)
1141       if (Merge(V.getStructField(I)))
1142         break;
1143     break;
1144   }
1145 
1146   case APValue::Union:
1147     if (V.getUnionField())
1148       Merge(V.getUnionValue());
1149     break;
1150 
1151   case APValue::Array: {
1152     for (unsigned I = 0, N = V.getArrayInitializedElts(); I != N; ++I)
1153       if (Merge(V.getArrayInitializedElt(I)))
1154         break;
1155     if (V.hasArrayFiller())
1156       Merge(V.getArrayFiller());
1157     break;
1158   }
1159 
1160   case APValue::LValue: {
1161     if (!V.getLValueBase()) {
1162       // Null or absolute address: this is external.
1163     } else if (const auto *VD =
1164                    V.getLValueBase().dyn_cast<const ValueDecl *>()) {
1165       if (VD && MergeLV(getLVForDecl(VD, computation)))
1166         break;
1167     } else if (const auto TI = V.getLValueBase().dyn_cast<TypeInfoLValue>()) {
1168       if (MergeLV(getLVForType(*TI.getType(), computation)))
1169         break;
1170     } else if (const Expr *E = V.getLValueBase().dyn_cast<const Expr *>()) {
1171       // Almost all expression bases are internal. The exception is
1172       // lifetime-extended temporaries.
1173       // FIXME: These should be modeled as having the
1174       // LifetimeExtendedTemporaryDecl itself as the base.
1175       // FIXME: If we permit Objective-C object literals in template arguments,
1176       // they should not imply internal linkage.
1177       auto *MTE = dyn_cast<MaterializeTemporaryExpr>(E);
1178       if (!MTE || MTE->getStorageDuration() == SD_FullExpression)
1179         return LinkageInfo::internal();
1180       if (MergeLV(getLVForDecl(MTE->getExtendingDecl(), computation)))
1181         break;
1182     } else {
1183       assert(V.getLValueBase().is<DynamicAllocLValue>() &&
1184              "unexpected LValueBase kind");
1185       return LinkageInfo::internal();
1186     }
1187     // The lvalue path doesn't matter: pointers to all subobjects always have
1188     // the same visibility as pointers to the complete object.
1189     break;
1190   }
1191 
1192   case APValue::MemberPointer:
1193     if (const NamedDecl *D = V.getMemberPointerDecl())
1194       MergeLV(getLVForDecl(D, computation));
1195     // Note that we could have a base-to-derived conversion here to a member of
1196     // a derived class with less linkage/visibility. That's covered by the
1197     // linkage and visibility of the value's type.
1198     break;
1199   }
1200 
1201   return LV;
1202 }
1203