xref: /freebsd/contrib/llvm-project/clang/lib/AST/APValue.cpp (revision cfd6422a5217410fbd66f7a7a8a64d9d85e61229) 
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 "clang/AST/ASTContext.h"
15 #include "clang/AST/CharUnits.h"
16 #include "clang/AST/DeclCXX.h"
17 #include "clang/AST/Expr.h"
18 #include "clang/AST/Type.h"
19 #include "llvm/Support/ErrorHandling.h"
20 #include "llvm/Support/raw_ostream.h"
21 using namespace clang;
22 
23 /// The identity of a type_info object depends on the canonical unqualified
24 /// type only.
25 TypeInfoLValue::TypeInfoLValue(const Type *T)
26     : T(T->getCanonicalTypeUnqualified().getTypePtr()) {}
27 
28 void TypeInfoLValue::print(llvm::raw_ostream &Out,
29                            const PrintingPolicy &Policy) const {
30   Out << "typeid(";
31   QualType(getType(), 0).print(Out, Policy);
32   Out << ")";
33 }
34 
35 static_assert(
36     1 << llvm::PointerLikeTypeTraits<TypeInfoLValue>::NumLowBitsAvailable <=
37         alignof(Type),
38     "Type is insufficiently aligned");
39 
40 APValue::LValueBase::LValueBase(const ValueDecl *P, unsigned I, unsigned V)
41     : Ptr(P), Local{I, V} {}
42 APValue::LValueBase::LValueBase(const Expr *P, unsigned I, unsigned V)
43     : Ptr(P), Local{I, V} {}
44 
45 APValue::LValueBase APValue::LValueBase::getDynamicAlloc(DynamicAllocLValue LV,
46                                                          QualType Type) {
47   LValueBase Base;
48   Base.Ptr = LV;
49   Base.DynamicAllocType = Type.getAsOpaquePtr();
50   return Base;
51 }
52 
53 APValue::LValueBase APValue::LValueBase::getTypeInfo(TypeInfoLValue LV,
54                                                      QualType TypeInfo) {
55   LValueBase Base;
56   Base.Ptr = LV;
57   Base.TypeInfoType = TypeInfo.getAsOpaquePtr();
58   return Base;
59 }
60 
61 unsigned APValue::LValueBase::getCallIndex() const {
62   return (is<TypeInfoLValue>() || is<DynamicAllocLValue>()) ? 0
63                                                             : Local.CallIndex;
64 }
65 
66 unsigned APValue::LValueBase::getVersion() const {
67   return (is<TypeInfoLValue>() || is<DynamicAllocLValue>()) ? 0 : Local.Version;
68 }
69 
70 QualType APValue::LValueBase::getTypeInfoType() const {
71   assert(is<TypeInfoLValue>() && "not a type_info lvalue");
72   return QualType::getFromOpaquePtr(TypeInfoType);
73 }
74 
75 QualType APValue::LValueBase::getDynamicAllocType() const {
76   assert(is<DynamicAllocLValue>() && "not a dynamic allocation lvalue");
77   return QualType::getFromOpaquePtr(DynamicAllocType);
78 }
79 
80 namespace clang {
81 bool operator==(const APValue::LValueBase &LHS,
82                 const APValue::LValueBase &RHS) {
83   if (LHS.Ptr != RHS.Ptr)
84     return false;
85   if (LHS.is<TypeInfoLValue>())
86     return true;
87   return LHS.Local.CallIndex == RHS.Local.CallIndex &&
88          LHS.Local.Version == RHS.Local.Version;
89 }
90 }
91 
92 namespace {
93   struct LVBase {
94     APValue::LValueBase Base;
95     CharUnits Offset;
96     unsigned PathLength;
97     bool IsNullPtr : 1;
98     bool IsOnePastTheEnd : 1;
99   };
100 }
101 
102 void *APValue::LValueBase::getOpaqueValue() const {
103   return Ptr.getOpaqueValue();
104 }
105 
106 bool APValue::LValueBase::isNull() const {
107   return Ptr.isNull();
108 }
109 
110 APValue::LValueBase::operator bool () const {
111   return static_cast<bool>(Ptr);
112 }
113 
114 clang::APValue::LValueBase
115 llvm::DenseMapInfo<clang::APValue::LValueBase>::getEmptyKey() {
116   return clang::APValue::LValueBase(
117       DenseMapInfo<const ValueDecl*>::getEmptyKey());
118 }
119 
120 clang::APValue::LValueBase
121 llvm::DenseMapInfo<clang::APValue::LValueBase>::getTombstoneKey() {
122   return clang::APValue::LValueBase(
123       DenseMapInfo<const ValueDecl*>::getTombstoneKey());
124 }
125 
126 namespace clang {
127 llvm::hash_code hash_value(const APValue::LValueBase &Base) {
128   if (Base.is<TypeInfoLValue>() || Base.is<DynamicAllocLValue>())
129     return llvm::hash_value(Base.getOpaqueValue());
130   return llvm::hash_combine(Base.getOpaqueValue(), Base.getCallIndex(),
131                             Base.getVersion());
132 }
133 }
134 
135 unsigned llvm::DenseMapInfo<clang::APValue::LValueBase>::getHashValue(
136     const clang::APValue::LValueBase &Base) {
137   return hash_value(Base);
138 }
139 
140 bool llvm::DenseMapInfo<clang::APValue::LValueBase>::isEqual(
141     const clang::APValue::LValueBase &LHS,
142     const clang::APValue::LValueBase &RHS) {
143   return LHS == RHS;
144 }
145 
146 struct APValue::LV : LVBase {
147   static const unsigned InlinePathSpace =
148       (DataSize - sizeof(LVBase)) / sizeof(LValuePathEntry);
149 
150   /// Path - The sequence of base classes, fields and array indices to follow to
151   /// walk from Base to the subobject. When performing GCC-style folding, there
152   /// may not be such a path.
153   union {
154     LValuePathEntry Path[InlinePathSpace];
155     LValuePathEntry *PathPtr;
156   };
157 
158   LV() { PathLength = (unsigned)-1; }
159   ~LV() { resizePath(0); }
160 
161   void resizePath(unsigned Length) {
162     if (Length == PathLength)
163       return;
164     if (hasPathPtr())
165       delete [] PathPtr;
166     PathLength = Length;
167     if (hasPathPtr())
168       PathPtr = new LValuePathEntry[Length];
169   }
170 
171   bool hasPath() const { return PathLength != (unsigned)-1; }
172   bool hasPathPtr() const { return hasPath() && PathLength > InlinePathSpace; }
173 
174   LValuePathEntry *getPath() { return hasPathPtr() ? PathPtr : Path; }
175   const LValuePathEntry *getPath() const {
176     return hasPathPtr() ? PathPtr : Path;
177   }
178 };
179 
180 namespace {
181   struct MemberPointerBase {
182     llvm::PointerIntPair<const ValueDecl*, 1, bool> MemberAndIsDerivedMember;
183     unsigned PathLength;
184   };
185 }
186 
187 struct APValue::MemberPointerData : MemberPointerBase {
188   static const unsigned InlinePathSpace =
189       (DataSize - sizeof(MemberPointerBase)) / sizeof(const CXXRecordDecl*);
190   typedef const CXXRecordDecl *PathElem;
191   union {
192     PathElem Path[InlinePathSpace];
193     PathElem *PathPtr;
194   };
195 
196   MemberPointerData() { PathLength = 0; }
197   ~MemberPointerData() { resizePath(0); }
198 
199   void resizePath(unsigned Length) {
200     if (Length == PathLength)
201       return;
202     if (hasPathPtr())
203       delete [] PathPtr;
204     PathLength = Length;
205     if (hasPathPtr())
206       PathPtr = new PathElem[Length];
207   }
208 
209   bool hasPathPtr() const { return PathLength > InlinePathSpace; }
210 
211   PathElem *getPath() { return hasPathPtr() ? PathPtr : Path; }
212   const PathElem *getPath() const {
213     return hasPathPtr() ? PathPtr : Path;
214   }
215 };
216 
217 // FIXME: Reduce the malloc traffic here.
218 
219 APValue::Arr::Arr(unsigned NumElts, unsigned Size) :
220   Elts(new APValue[NumElts + (NumElts != Size ? 1 : 0)]),
221   NumElts(NumElts), ArrSize(Size) {}
222 APValue::Arr::~Arr() { delete [] Elts; }
223 
224 APValue::StructData::StructData(unsigned NumBases, unsigned NumFields) :
225   Elts(new APValue[NumBases+NumFields]),
226   NumBases(NumBases), NumFields(NumFields) {}
227 APValue::StructData::~StructData() {
228   delete [] Elts;
229 }
230 
231 APValue::UnionData::UnionData() : Field(nullptr), Value(new APValue) {}
232 APValue::UnionData::~UnionData () {
233   delete Value;
234 }
235 
236 APValue::APValue(const APValue &RHS) : Kind(None) {
237   switch (RHS.getKind()) {
238   case None:
239   case Indeterminate:
240     Kind = RHS.getKind();
241     break;
242   case Int:
243     MakeInt();
244     setInt(RHS.getInt());
245     break;
246   case Float:
247     MakeFloat();
248     setFloat(RHS.getFloat());
249     break;
250   case FixedPoint: {
251     APFixedPoint FXCopy = RHS.getFixedPoint();
252     MakeFixedPoint(std::move(FXCopy));
253     break;
254   }
255   case Vector:
256     MakeVector();
257     setVector(((const Vec *)(const char *)RHS.Data.buffer)->Elts,
258               RHS.getVectorLength());
259     break;
260   case ComplexInt:
261     MakeComplexInt();
262     setComplexInt(RHS.getComplexIntReal(), RHS.getComplexIntImag());
263     break;
264   case ComplexFloat:
265     MakeComplexFloat();
266     setComplexFloat(RHS.getComplexFloatReal(), RHS.getComplexFloatImag());
267     break;
268   case LValue:
269     MakeLValue();
270     if (RHS.hasLValuePath())
271       setLValue(RHS.getLValueBase(), RHS.getLValueOffset(), RHS.getLValuePath(),
272                 RHS.isLValueOnePastTheEnd(), RHS.isNullPointer());
273     else
274       setLValue(RHS.getLValueBase(), RHS.getLValueOffset(), NoLValuePath(),
275                 RHS.isNullPointer());
276     break;
277   case Array:
278     MakeArray(RHS.getArrayInitializedElts(), RHS.getArraySize());
279     for (unsigned I = 0, N = RHS.getArrayInitializedElts(); I != N; ++I)
280       getArrayInitializedElt(I) = RHS.getArrayInitializedElt(I);
281     if (RHS.hasArrayFiller())
282       getArrayFiller() = RHS.getArrayFiller();
283     break;
284   case Struct:
285     MakeStruct(RHS.getStructNumBases(), RHS.getStructNumFields());
286     for (unsigned I = 0, N = RHS.getStructNumBases(); I != N; ++I)
287       getStructBase(I) = RHS.getStructBase(I);
288     for (unsigned I = 0, N = RHS.getStructNumFields(); I != N; ++I)
289       getStructField(I) = RHS.getStructField(I);
290     break;
291   case Union:
292     MakeUnion();
293     setUnion(RHS.getUnionField(), RHS.getUnionValue());
294     break;
295   case MemberPointer:
296     MakeMemberPointer(RHS.getMemberPointerDecl(),
297                       RHS.isMemberPointerToDerivedMember(),
298                       RHS.getMemberPointerPath());
299     break;
300   case AddrLabelDiff:
301     MakeAddrLabelDiff();
302     setAddrLabelDiff(RHS.getAddrLabelDiffLHS(), RHS.getAddrLabelDiffRHS());
303     break;
304   }
305 }
306 
307 void APValue::DestroyDataAndMakeUninit() {
308   if (Kind == Int)
309     ((APSInt*)(char*)Data.buffer)->~APSInt();
310   else if (Kind == Float)
311     ((APFloat*)(char*)Data.buffer)->~APFloat();
312   else if (Kind == FixedPoint)
313     ((APFixedPoint *)(char *)Data.buffer)->~APFixedPoint();
314   else if (Kind == Vector)
315     ((Vec*)(char*)Data.buffer)->~Vec();
316   else if (Kind == ComplexInt)
317     ((ComplexAPSInt*)(char*)Data.buffer)->~ComplexAPSInt();
318   else if (Kind == ComplexFloat)
319     ((ComplexAPFloat*)(char*)Data.buffer)->~ComplexAPFloat();
320   else if (Kind == LValue)
321     ((LV*)(char*)Data.buffer)->~LV();
322   else if (Kind == Array)
323     ((Arr*)(char*)Data.buffer)->~Arr();
324   else if (Kind == Struct)
325     ((StructData*)(char*)Data.buffer)->~StructData();
326   else if (Kind == Union)
327     ((UnionData*)(char*)Data.buffer)->~UnionData();
328   else if (Kind == MemberPointer)
329     ((MemberPointerData*)(char*)Data.buffer)->~MemberPointerData();
330   else if (Kind == AddrLabelDiff)
331     ((AddrLabelDiffData*)(char*)Data.buffer)->~AddrLabelDiffData();
332   Kind = None;
333 }
334 
335 bool APValue::needsCleanup() const {
336   switch (getKind()) {
337   case None:
338   case Indeterminate:
339   case AddrLabelDiff:
340     return false;
341   case Struct:
342   case Union:
343   case Array:
344   case Vector:
345     return true;
346   case Int:
347     return getInt().needsCleanup();
348   case Float:
349     return getFloat().needsCleanup();
350   case FixedPoint:
351     return getFixedPoint().getValue().needsCleanup();
352   case ComplexFloat:
353     assert(getComplexFloatImag().needsCleanup() ==
354                getComplexFloatReal().needsCleanup() &&
355            "In _Complex float types, real and imaginary values always have the "
356            "same size.");
357     return getComplexFloatReal().needsCleanup();
358   case ComplexInt:
359     assert(getComplexIntImag().needsCleanup() ==
360                getComplexIntReal().needsCleanup() &&
361            "In _Complex int types, real and imaginary values must have the "
362            "same size.");
363     return getComplexIntReal().needsCleanup();
364   case LValue:
365     return reinterpret_cast<const LV *>(Data.buffer)->hasPathPtr();
366   case MemberPointer:
367     return reinterpret_cast<const MemberPointerData *>(Data.buffer)
368         ->hasPathPtr();
369   }
370   llvm_unreachable("Unknown APValue kind!");
371 }
372 
373 void APValue::swap(APValue &RHS) {
374   std::swap(Kind, RHS.Kind);
375   char TmpData[DataSize];
376   memcpy(TmpData, Data.buffer, DataSize);
377   memcpy(Data.buffer, RHS.Data.buffer, DataSize);
378   memcpy(RHS.Data.buffer, TmpData, DataSize);
379 }
380 
381 static double GetApproxValue(const llvm::APFloat &F) {
382   llvm::APFloat V = F;
383   bool ignored;
384   V.convert(llvm::APFloat::IEEEdouble(), llvm::APFloat::rmNearestTiesToEven,
385             &ignored);
386   return V.convertToDouble();
387 }
388 
389 void APValue::printPretty(raw_ostream &Out, const ASTContext &Ctx,
390                           QualType Ty) const {
391   switch (getKind()) {
392   case APValue::None:
393     Out << "<out of lifetime>";
394     return;
395   case APValue::Indeterminate:
396     Out << "<uninitialized>";
397     return;
398   case APValue::Int:
399     if (Ty->isBooleanType())
400       Out << (getInt().getBoolValue() ? "true" : "false");
401     else
402       Out << getInt();
403     return;
404   case APValue::Float:
405     Out << GetApproxValue(getFloat());
406     return;
407   case APValue::FixedPoint:
408     Out << getFixedPoint();
409     return;
410   case APValue::Vector: {
411     Out << '{';
412     QualType ElemTy = Ty->castAs<VectorType>()->getElementType();
413     getVectorElt(0).printPretty(Out, Ctx, ElemTy);
414     for (unsigned i = 1; i != getVectorLength(); ++i) {
415       Out << ", ";
416       getVectorElt(i).printPretty(Out, Ctx, ElemTy);
417     }
418     Out << '}';
419     return;
420   }
421   case APValue::ComplexInt:
422     Out << getComplexIntReal() << "+" << getComplexIntImag() << "i";
423     return;
424   case APValue::ComplexFloat:
425     Out << GetApproxValue(getComplexFloatReal()) << "+"
426         << GetApproxValue(getComplexFloatImag()) << "i";
427     return;
428   case APValue::LValue: {
429     bool IsReference = Ty->isReferenceType();
430     QualType InnerTy
431       = IsReference ? Ty.getNonReferenceType() : Ty->getPointeeType();
432     if (InnerTy.isNull())
433       InnerTy = Ty;
434 
435     LValueBase Base = getLValueBase();
436     if (!Base) {
437       if (isNullPointer()) {
438         Out << (Ctx.getLangOpts().CPlusPlus11 ? "nullptr" : "0");
439       } else if (IsReference) {
440         Out << "*(" << InnerTy.stream(Ctx.getPrintingPolicy()) << "*)"
441             << getLValueOffset().getQuantity();
442       } else {
443         Out << "(" << Ty.stream(Ctx.getPrintingPolicy()) << ")"
444             << getLValueOffset().getQuantity();
445       }
446       return;
447     }
448 
449     if (!hasLValuePath()) {
450       // No lvalue path: just print the offset.
451       CharUnits O = getLValueOffset();
452       CharUnits S = Ctx.getTypeSizeInChars(InnerTy);
453       if (!O.isZero()) {
454         if (IsReference)
455           Out << "*(";
456         if (O % S) {
457           Out << "(char*)";
458           S = CharUnits::One();
459         }
460         Out << '&';
461       } else if (!IsReference) {
462         Out << '&';
463       }
464 
465       if (const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>())
466         Out << *VD;
467       else if (TypeInfoLValue TI = Base.dyn_cast<TypeInfoLValue>()) {
468         TI.print(Out, Ctx.getPrintingPolicy());
469       } else if (DynamicAllocLValue DA = Base.dyn_cast<DynamicAllocLValue>()) {
470         Out << "{*new "
471             << Base.getDynamicAllocType().stream(Ctx.getPrintingPolicy()) << "#"
472             << DA.getIndex() << "}";
473       } else {
474         assert(Base.get<const Expr *>() != nullptr &&
475                "Expecting non-null Expr");
476         Base.get<const Expr*>()->printPretty(Out, nullptr,
477                                              Ctx.getPrintingPolicy());
478       }
479 
480       if (!O.isZero()) {
481         Out << " + " << (O / S);
482         if (IsReference)
483           Out << ')';
484       }
485       return;
486     }
487 
488     // We have an lvalue path. Print it out nicely.
489     if (!IsReference)
490       Out << '&';
491     else if (isLValueOnePastTheEnd())
492       Out << "*(&";
493 
494     QualType ElemTy;
495     if (const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>()) {
496       Out << *VD;
497       ElemTy = VD->getType();
498     } else if (TypeInfoLValue TI = Base.dyn_cast<TypeInfoLValue>()) {
499       TI.print(Out, Ctx.getPrintingPolicy());
500       ElemTy = Base.getTypeInfoType();
501     } else if (DynamicAllocLValue DA = Base.dyn_cast<DynamicAllocLValue>()) {
502       Out << "{*new "
503           << Base.getDynamicAllocType().stream(Ctx.getPrintingPolicy()) << "#"
504           << DA.getIndex() << "}";
505       ElemTy = Base.getDynamicAllocType();
506     } else {
507       const Expr *E = Base.get<const Expr*>();
508       assert(E != nullptr && "Expecting non-null Expr");
509       E->printPretty(Out, nullptr, Ctx.getPrintingPolicy());
510       // FIXME: This is wrong if E is a MaterializeTemporaryExpr with an lvalue
511       // adjustment.
512       ElemTy = E->getType();
513     }
514 
515     ArrayRef<LValuePathEntry> Path = getLValuePath();
516     const CXXRecordDecl *CastToBase = nullptr;
517     for (unsigned I = 0, N = Path.size(); I != N; ++I) {
518       if (ElemTy->getAs<RecordType>()) {
519         // The lvalue refers to a class type, so the next path entry is a base
520         // or member.
521         const Decl *BaseOrMember = Path[I].getAsBaseOrMember().getPointer();
522         if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(BaseOrMember)) {
523           CastToBase = RD;
524           ElemTy = Ctx.getRecordType(RD);
525         } else {
526           const ValueDecl *VD = cast<ValueDecl>(BaseOrMember);
527           Out << ".";
528           if (CastToBase)
529             Out << *CastToBase << "::";
530           Out << *VD;
531           ElemTy = VD->getType();
532         }
533       } else {
534         // The lvalue must refer to an array.
535         Out << '[' << Path[I].getAsArrayIndex() << ']';
536         ElemTy = Ctx.getAsArrayType(ElemTy)->getElementType();
537       }
538     }
539 
540     // Handle formatting of one-past-the-end lvalues.
541     if (isLValueOnePastTheEnd()) {
542       // FIXME: If CastToBase is non-0, we should prefix the output with
543       // "(CastToBase*)".
544       Out << " + 1";
545       if (IsReference)
546         Out << ')';
547     }
548     return;
549   }
550   case APValue::Array: {
551     const ArrayType *AT = Ctx.getAsArrayType(Ty);
552     QualType ElemTy = AT->getElementType();
553     Out << '{';
554     if (unsigned N = getArrayInitializedElts()) {
555       getArrayInitializedElt(0).printPretty(Out, Ctx, ElemTy);
556       for (unsigned I = 1; I != N; ++I) {
557         Out << ", ";
558         if (I == 10) {
559           // Avoid printing out the entire contents of large arrays.
560           Out << "...";
561           break;
562         }
563         getArrayInitializedElt(I).printPretty(Out, Ctx, ElemTy);
564       }
565     }
566     Out << '}';
567     return;
568   }
569   case APValue::Struct: {
570     Out << '{';
571     const RecordDecl *RD = Ty->castAs<RecordType>()->getDecl();
572     bool First = true;
573     if (unsigned N = getStructNumBases()) {
574       const CXXRecordDecl *CD = cast<CXXRecordDecl>(RD);
575       CXXRecordDecl::base_class_const_iterator BI = CD->bases_begin();
576       for (unsigned I = 0; I != N; ++I, ++BI) {
577         assert(BI != CD->bases_end());
578         if (!First)
579           Out << ", ";
580         getStructBase(I).printPretty(Out, Ctx, BI->getType());
581         First = false;
582       }
583     }
584     for (const auto *FI : RD->fields()) {
585       if (!First)
586         Out << ", ";
587       if (FI->isUnnamedBitfield()) continue;
588       getStructField(FI->getFieldIndex()).
589         printPretty(Out, Ctx, FI->getType());
590       First = false;
591     }
592     Out << '}';
593     return;
594   }
595   case APValue::Union:
596     Out << '{';
597     if (const FieldDecl *FD = getUnionField()) {
598       Out << "." << *FD << " = ";
599       getUnionValue().printPretty(Out, Ctx, FD->getType());
600     }
601     Out << '}';
602     return;
603   case APValue::MemberPointer:
604     // FIXME: This is not enough to unambiguously identify the member in a
605     // multiple-inheritance scenario.
606     if (const ValueDecl *VD = getMemberPointerDecl()) {
607       Out << '&' << *cast<CXXRecordDecl>(VD->getDeclContext()) << "::" << *VD;
608       return;
609     }
610     Out << "0";
611     return;
612   case APValue::AddrLabelDiff:
613     Out << "&&" << getAddrLabelDiffLHS()->getLabel()->getName();
614     Out << " - ";
615     Out << "&&" << getAddrLabelDiffRHS()->getLabel()->getName();
616     return;
617   }
618   llvm_unreachable("Unknown APValue kind!");
619 }
620 
621 std::string APValue::getAsString(const ASTContext &Ctx, QualType Ty) const {
622   std::string Result;
623   llvm::raw_string_ostream Out(Result);
624   printPretty(Out, Ctx, Ty);
625   Out.flush();
626   return Result;
627 }
628 
629 bool APValue::toIntegralConstant(APSInt &Result, QualType SrcTy,
630                                  const ASTContext &Ctx) const {
631   if (isInt()) {
632     Result = getInt();
633     return true;
634   }
635 
636   if (isLValue() && isNullPointer()) {
637     Result = Ctx.MakeIntValue(Ctx.getTargetNullPointerValue(SrcTy), SrcTy);
638     return true;
639   }
640 
641   if (isLValue() && !getLValueBase()) {
642     Result = Ctx.MakeIntValue(getLValueOffset().getQuantity(), SrcTy);
643     return true;
644   }
645 
646   return false;
647 }
648 
649 const APValue::LValueBase APValue::getLValueBase() const {
650   assert(isLValue() && "Invalid accessor");
651   return ((const LV*)(const void*)Data.buffer)->Base;
652 }
653 
654 bool APValue::isLValueOnePastTheEnd() const {
655   assert(isLValue() && "Invalid accessor");
656   return ((const LV*)(const void*)Data.buffer)->IsOnePastTheEnd;
657 }
658 
659 CharUnits &APValue::getLValueOffset() {
660   assert(isLValue() && "Invalid accessor");
661   return ((LV*)(void*)Data.buffer)->Offset;
662 }
663 
664 bool APValue::hasLValuePath() const {
665   assert(isLValue() && "Invalid accessor");
666   return ((const LV*)(const char*)Data.buffer)->hasPath();
667 }
668 
669 ArrayRef<APValue::LValuePathEntry> APValue::getLValuePath() const {
670   assert(isLValue() && hasLValuePath() && "Invalid accessor");
671   const LV &LVal = *((const LV*)(const char*)Data.buffer);
672   return llvm::makeArrayRef(LVal.getPath(), LVal.PathLength);
673 }
674 
675 unsigned APValue::getLValueCallIndex() const {
676   assert(isLValue() && "Invalid accessor");
677   return ((const LV*)(const char*)Data.buffer)->Base.getCallIndex();
678 }
679 
680 unsigned APValue::getLValueVersion() const {
681   assert(isLValue() && "Invalid accessor");
682   return ((const LV*)(const char*)Data.buffer)->Base.getVersion();
683 }
684 
685 bool APValue::isNullPointer() const {
686   assert(isLValue() && "Invalid usage");
687   return ((const LV*)(const char*)Data.buffer)->IsNullPtr;
688 }
689 
690 void APValue::setLValue(LValueBase B, const CharUnits &O, NoLValuePath,
691                         bool IsNullPtr) {
692   assert(isLValue() && "Invalid accessor");
693   LV &LVal = *((LV*)(char*)Data.buffer);
694   LVal.Base = B;
695   LVal.IsOnePastTheEnd = false;
696   LVal.Offset = O;
697   LVal.resizePath((unsigned)-1);
698   LVal.IsNullPtr = IsNullPtr;
699 }
700 
701 void APValue::setLValue(LValueBase B, const CharUnits &O,
702                         ArrayRef<LValuePathEntry> Path, bool IsOnePastTheEnd,
703                         bool IsNullPtr) {
704   assert(isLValue() && "Invalid accessor");
705   LV &LVal = *((LV*)(char*)Data.buffer);
706   LVal.Base = B;
707   LVal.IsOnePastTheEnd = IsOnePastTheEnd;
708   LVal.Offset = O;
709   LVal.resizePath(Path.size());
710   memcpy(LVal.getPath(), Path.data(), Path.size() * sizeof(LValuePathEntry));
711   LVal.IsNullPtr = IsNullPtr;
712 }
713 
714 const ValueDecl *APValue::getMemberPointerDecl() const {
715   assert(isMemberPointer() && "Invalid accessor");
716   const MemberPointerData &MPD =
717       *((const MemberPointerData *)(const char *)Data.buffer);
718   return MPD.MemberAndIsDerivedMember.getPointer();
719 }
720 
721 bool APValue::isMemberPointerToDerivedMember() const {
722   assert(isMemberPointer() && "Invalid accessor");
723   const MemberPointerData &MPD =
724       *((const MemberPointerData *)(const char *)Data.buffer);
725   return MPD.MemberAndIsDerivedMember.getInt();
726 }
727 
728 ArrayRef<const CXXRecordDecl*> APValue::getMemberPointerPath() const {
729   assert(isMemberPointer() && "Invalid accessor");
730   const MemberPointerData &MPD =
731       *((const MemberPointerData *)(const char *)Data.buffer);
732   return llvm::makeArrayRef(MPD.getPath(), MPD.PathLength);
733 }
734 
735 void APValue::MakeLValue() {
736   assert(isAbsent() && "Bad state change");
737   static_assert(sizeof(LV) <= DataSize, "LV too big");
738   new ((void*)(char*)Data.buffer) LV();
739   Kind = LValue;
740 }
741 
742 void APValue::MakeArray(unsigned InitElts, unsigned Size) {
743   assert(isAbsent() && "Bad state change");
744   new ((void*)(char*)Data.buffer) Arr(InitElts, Size);
745   Kind = Array;
746 }
747 
748 void APValue::MakeMemberPointer(const ValueDecl *Member, bool IsDerivedMember,
749                                 ArrayRef<const CXXRecordDecl*> Path) {
750   assert(isAbsent() && "Bad state change");
751   MemberPointerData *MPD = new ((void*)(char*)Data.buffer) MemberPointerData;
752   Kind = MemberPointer;
753   MPD->MemberAndIsDerivedMember.setPointer(Member);
754   MPD->MemberAndIsDerivedMember.setInt(IsDerivedMember);
755   MPD->resizePath(Path.size());
756   memcpy(MPD->getPath(), Path.data(), Path.size()*sizeof(const CXXRecordDecl*));
757 }
758