xref: /freebsd/contrib/llvm-project/clang/lib/CodeGen/MicrosoftCXXABI.cpp (revision 25ecdc7d52770caf1c9b44b5ec11f468f6b636f3)
1 //===--- MicrosoftCXXABI.cpp - Emit LLVM Code from ASTs for a Module ------===//
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 provides C++ code generation targeting the Microsoft Visual C++ ABI.
10 // The class in this file generates structures that follow the Microsoft
11 // Visual C++ ABI, which is actually not very well documented at all outside
12 // of Microsoft.
13 //
14 //===----------------------------------------------------------------------===//
15 
16 #include "CGCXXABI.h"
17 #include "CGCleanup.h"
18 #include "CGVTables.h"
19 #include "CodeGenModule.h"
20 #include "CodeGenTypes.h"
21 #include "TargetInfo.h"
22 #include "clang/AST/Attr.h"
23 #include "clang/AST/CXXInheritance.h"
24 #include "clang/AST/Decl.h"
25 #include "clang/AST/DeclCXX.h"
26 #include "clang/AST/StmtCXX.h"
27 #include "clang/AST/VTableBuilder.h"
28 #include "clang/CodeGen/ConstantInitBuilder.h"
29 #include "llvm/ADT/StringExtras.h"
30 #include "llvm/ADT/StringSet.h"
31 #include "llvm/IR/Intrinsics.h"
32 
33 using namespace clang;
34 using namespace CodeGen;
35 
36 namespace {
37 
38 /// Holds all the vbtable globals for a given class.
39 struct VBTableGlobals {
40   const VPtrInfoVector *VBTables;
41   SmallVector<llvm::GlobalVariable *, 2> Globals;
42 };
43 
44 class MicrosoftCXXABI : public CGCXXABI {
45 public:
46   MicrosoftCXXABI(CodeGenModule &CGM)
47       : CGCXXABI(CGM), BaseClassDescriptorType(nullptr),
48         ClassHierarchyDescriptorType(nullptr),
49         CompleteObjectLocatorType(nullptr), CatchableTypeType(nullptr),
50         ThrowInfoType(nullptr) {}
51 
52   bool HasThisReturn(GlobalDecl GD) const override;
53   bool hasMostDerivedReturn(GlobalDecl GD) const override;
54 
55   bool classifyReturnType(CGFunctionInfo &FI) const override;
56 
57   RecordArgABI getRecordArgABI(const CXXRecordDecl *RD) const override;
58 
59   bool isSRetParameterAfterThis() const override { return true; }
60 
61   bool isThisCompleteObject(GlobalDecl GD) const override {
62     // The Microsoft ABI doesn't use separate complete-object vs.
63     // base-object variants of constructors, but it does of destructors.
64     if (isa<CXXDestructorDecl>(GD.getDecl())) {
65       switch (GD.getDtorType()) {
66       case Dtor_Complete:
67       case Dtor_Deleting:
68         return true;
69 
70       case Dtor_Base:
71         return false;
72 
73       case Dtor_Comdat: llvm_unreachable("emitting dtor comdat as function?");
74       }
75       llvm_unreachable("bad dtor kind");
76     }
77 
78     // No other kinds.
79     return false;
80   }
81 
82   size_t getSrcArgforCopyCtor(const CXXConstructorDecl *CD,
83                               FunctionArgList &Args) const override {
84     assert(Args.size() >= 2 &&
85            "expected the arglist to have at least two args!");
86     // The 'most_derived' parameter goes second if the ctor is variadic and
87     // has v-bases.
88     if (CD->getParent()->getNumVBases() > 0 &&
89         CD->getType()->castAs<FunctionProtoType>()->isVariadic())
90       return 2;
91     return 1;
92   }
93 
94   std::vector<CharUnits> getVBPtrOffsets(const CXXRecordDecl *RD) override {
95     std::vector<CharUnits> VBPtrOffsets;
96     const ASTContext &Context = getContext();
97     const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
98 
99     const VBTableGlobals &VBGlobals = enumerateVBTables(RD);
100     for (const std::unique_ptr<VPtrInfo> &VBT : *VBGlobals.VBTables) {
101       const ASTRecordLayout &SubobjectLayout =
102           Context.getASTRecordLayout(VBT->IntroducingObject);
103       CharUnits Offs = VBT->NonVirtualOffset;
104       Offs += SubobjectLayout.getVBPtrOffset();
105       if (VBT->getVBaseWithVPtr())
106         Offs += Layout.getVBaseClassOffset(VBT->getVBaseWithVPtr());
107       VBPtrOffsets.push_back(Offs);
108     }
109     llvm::array_pod_sort(VBPtrOffsets.begin(), VBPtrOffsets.end());
110     return VBPtrOffsets;
111   }
112 
113   StringRef GetPureVirtualCallName() override { return "_purecall"; }
114   StringRef GetDeletedVirtualCallName() override { return "_purecall"; }
115 
116   void emitVirtualObjectDelete(CodeGenFunction &CGF, const CXXDeleteExpr *DE,
117                                Address Ptr, QualType ElementType,
118                                const CXXDestructorDecl *Dtor) override;
119 
120   void emitRethrow(CodeGenFunction &CGF, bool isNoReturn) override;
121   void emitThrow(CodeGenFunction &CGF, const CXXThrowExpr *E) override;
122 
123   void emitBeginCatch(CodeGenFunction &CGF, const CXXCatchStmt *C) override;
124 
125   llvm::GlobalVariable *getMSCompleteObjectLocator(const CXXRecordDecl *RD,
126                                                    const VPtrInfo &Info);
127 
128   llvm::Constant *getAddrOfRTTIDescriptor(QualType Ty) override;
129   CatchTypeInfo
130   getAddrOfCXXCatchHandlerType(QualType Ty, QualType CatchHandlerType) override;
131 
132   /// MSVC needs an extra flag to indicate a catchall.
133   CatchTypeInfo getCatchAllTypeInfo() override {
134     return CatchTypeInfo{nullptr, 0x40};
135   }
136 
137   bool shouldTypeidBeNullChecked(bool IsDeref, QualType SrcRecordTy) override;
138   void EmitBadTypeidCall(CodeGenFunction &CGF) override;
139   llvm::Value *EmitTypeid(CodeGenFunction &CGF, QualType SrcRecordTy,
140                           Address ThisPtr,
141                           llvm::Type *StdTypeInfoPtrTy) override;
142 
143   bool shouldDynamicCastCallBeNullChecked(bool SrcIsPtr,
144                                           QualType SrcRecordTy) override;
145 
146   llvm::Value *EmitDynamicCastCall(CodeGenFunction &CGF, Address Value,
147                                    QualType SrcRecordTy, QualType DestTy,
148                                    QualType DestRecordTy,
149                                    llvm::BasicBlock *CastEnd) override;
150 
151   llvm::Value *EmitDynamicCastToVoid(CodeGenFunction &CGF, Address Value,
152                                      QualType SrcRecordTy,
153                                      QualType DestTy) override;
154 
155   bool EmitBadCastCall(CodeGenFunction &CGF) override;
156   bool canSpeculativelyEmitVTable(const CXXRecordDecl *RD) const override {
157     return false;
158   }
159 
160   llvm::Value *
161   GetVirtualBaseClassOffset(CodeGenFunction &CGF, Address This,
162                             const CXXRecordDecl *ClassDecl,
163                             const CXXRecordDecl *BaseClassDecl) override;
164 
165   llvm::BasicBlock *
166   EmitCtorCompleteObjectHandler(CodeGenFunction &CGF,
167                                 const CXXRecordDecl *RD) override;
168 
169   llvm::BasicBlock *
170   EmitDtorCompleteObjectHandler(CodeGenFunction &CGF);
171 
172   void initializeHiddenVirtualInheritanceMembers(CodeGenFunction &CGF,
173                                               const CXXRecordDecl *RD) override;
174 
175   void EmitCXXConstructors(const CXXConstructorDecl *D) override;
176 
177   // Background on MSVC destructors
178   // ==============================
179   //
180   // Both Itanium and MSVC ABIs have destructor variants.  The variant names
181   // roughly correspond in the following way:
182   //   Itanium       Microsoft
183   //   Base       -> no name, just ~Class
184   //   Complete   -> vbase destructor
185   //   Deleting   -> scalar deleting destructor
186   //                 vector deleting destructor
187   //
188   // The base and complete destructors are the same as in Itanium, although the
189   // complete destructor does not accept a VTT parameter when there are virtual
190   // bases.  A separate mechanism involving vtordisps is used to ensure that
191   // virtual methods of destroyed subobjects are not called.
192   //
193   // The deleting destructors accept an i32 bitfield as a second parameter.  Bit
194   // 1 indicates if the memory should be deleted.  Bit 2 indicates if the this
195   // pointer points to an array.  The scalar deleting destructor assumes that
196   // bit 2 is zero, and therefore does not contain a loop.
197   //
198   // For virtual destructors, only one entry is reserved in the vftable, and it
199   // always points to the vector deleting destructor.  The vector deleting
200   // destructor is the most general, so it can be used to destroy objects in
201   // place, delete single heap objects, or delete arrays.
202   //
203   // A TU defining a non-inline destructor is only guaranteed to emit a base
204   // destructor, and all of the other variants are emitted on an as-needed basis
205   // in COMDATs.  Because a non-base destructor can be emitted in a TU that
206   // lacks a definition for the destructor, non-base destructors must always
207   // delegate to or alias the base destructor.
208 
209   AddedStructorArgCounts
210   buildStructorSignature(GlobalDecl GD,
211                          SmallVectorImpl<CanQualType> &ArgTys) override;
212 
213   /// Non-base dtors should be emitted as delegating thunks in this ABI.
214   bool useThunkForDtorVariant(const CXXDestructorDecl *Dtor,
215                               CXXDtorType DT) const override {
216     return DT != Dtor_Base;
217   }
218 
219   void setCXXDestructorDLLStorage(llvm::GlobalValue *GV,
220                                   const CXXDestructorDecl *Dtor,
221                                   CXXDtorType DT) const override;
222 
223   llvm::GlobalValue::LinkageTypes
224   getCXXDestructorLinkage(GVALinkage Linkage, const CXXDestructorDecl *Dtor,
225                           CXXDtorType DT) const override;
226 
227   void EmitCXXDestructors(const CXXDestructorDecl *D) override;
228 
229   const CXXRecordDecl *
230   getThisArgumentTypeForMethod(const CXXMethodDecl *MD) override {
231     if (MD->isVirtual() && !isa<CXXDestructorDecl>(MD)) {
232       MethodVFTableLocation ML =
233           CGM.getMicrosoftVTableContext().getMethodVFTableLocation(MD);
234       // The vbases might be ordered differently in the final overrider object
235       // and the complete object, so the "this" argument may sometimes point to
236       // memory that has no particular type (e.g. past the complete object).
237       // In this case, we just use a generic pointer type.
238       // FIXME: might want to have a more precise type in the non-virtual
239       // multiple inheritance case.
240       if (ML.VBase || !ML.VFPtrOffset.isZero())
241         return nullptr;
242     }
243     return MD->getParent();
244   }
245 
246   Address
247   adjustThisArgumentForVirtualFunctionCall(CodeGenFunction &CGF, GlobalDecl GD,
248                                            Address This,
249                                            bool VirtualCall) override;
250 
251   void addImplicitStructorParams(CodeGenFunction &CGF, QualType &ResTy,
252                                  FunctionArgList &Params) override;
253 
254   void EmitInstanceFunctionProlog(CodeGenFunction &CGF) override;
255 
256   AddedStructorArgs getImplicitConstructorArgs(CodeGenFunction &CGF,
257                                                const CXXConstructorDecl *D,
258                                                CXXCtorType Type,
259                                                bool ForVirtualBase,
260                                                bool Delegating) override;
261 
262   llvm::Value *getCXXDestructorImplicitParam(CodeGenFunction &CGF,
263                                              const CXXDestructorDecl *DD,
264                                              CXXDtorType Type,
265                                              bool ForVirtualBase,
266                                              bool Delegating) override;
267 
268   void EmitDestructorCall(CodeGenFunction &CGF, const CXXDestructorDecl *DD,
269                           CXXDtorType Type, bool ForVirtualBase,
270                           bool Delegating, Address This,
271                           QualType ThisTy) override;
272 
273   void emitVTableTypeMetadata(const VPtrInfo &Info, const CXXRecordDecl *RD,
274                               llvm::GlobalVariable *VTable);
275 
276   void emitVTableDefinitions(CodeGenVTables &CGVT,
277                              const CXXRecordDecl *RD) override;
278 
279   bool isVirtualOffsetNeededForVTableField(CodeGenFunction &CGF,
280                                            CodeGenFunction::VPtr Vptr) override;
281 
282   /// Don't initialize vptrs if dynamic class
283   /// is marked with with the 'novtable' attribute.
284   bool doStructorsInitializeVPtrs(const CXXRecordDecl *VTableClass) override {
285     return !VTableClass->hasAttr<MSNoVTableAttr>();
286   }
287 
288   llvm::Constant *
289   getVTableAddressPoint(BaseSubobject Base,
290                         const CXXRecordDecl *VTableClass) override;
291 
292   llvm::Value *getVTableAddressPointInStructor(
293       CodeGenFunction &CGF, const CXXRecordDecl *VTableClass,
294       BaseSubobject Base, const CXXRecordDecl *NearestVBase) override;
295 
296   llvm::Constant *
297   getVTableAddressPointForConstExpr(BaseSubobject Base,
298                                     const CXXRecordDecl *VTableClass) override;
299 
300   llvm::GlobalVariable *getAddrOfVTable(const CXXRecordDecl *RD,
301                                         CharUnits VPtrOffset) override;
302 
303   CGCallee getVirtualFunctionPointer(CodeGenFunction &CGF, GlobalDecl GD,
304                                      Address This, llvm::Type *Ty,
305                                      SourceLocation Loc) override;
306 
307   llvm::Value *EmitVirtualDestructorCall(CodeGenFunction &CGF,
308                                          const CXXDestructorDecl *Dtor,
309                                          CXXDtorType DtorType, Address This,
310                                          DeleteOrMemberCallExpr E) override;
311 
312   void adjustCallArgsForDestructorThunk(CodeGenFunction &CGF, GlobalDecl GD,
313                                         CallArgList &CallArgs) override {
314     assert(GD.getDtorType() == Dtor_Deleting &&
315            "Only deleting destructor thunks are available in this ABI");
316     CallArgs.add(RValue::get(getStructorImplicitParamValue(CGF)),
317                  getContext().IntTy);
318   }
319 
320   void emitVirtualInheritanceTables(const CXXRecordDecl *RD) override;
321 
322   llvm::GlobalVariable *
323   getAddrOfVBTable(const VPtrInfo &VBT, const CXXRecordDecl *RD,
324                    llvm::GlobalVariable::LinkageTypes Linkage);
325 
326   llvm::GlobalVariable *
327   getAddrOfVirtualDisplacementMap(const CXXRecordDecl *SrcRD,
328                                   const CXXRecordDecl *DstRD) {
329     SmallString<256> OutName;
330     llvm::raw_svector_ostream Out(OutName);
331     getMangleContext().mangleCXXVirtualDisplacementMap(SrcRD, DstRD, Out);
332     StringRef MangledName = OutName.str();
333 
334     if (auto *VDispMap = CGM.getModule().getNamedGlobal(MangledName))
335       return VDispMap;
336 
337     MicrosoftVTableContext &VTContext = CGM.getMicrosoftVTableContext();
338     unsigned NumEntries = 1 + SrcRD->getNumVBases();
339     SmallVector<llvm::Constant *, 4> Map(NumEntries,
340                                          llvm::UndefValue::get(CGM.IntTy));
341     Map[0] = llvm::ConstantInt::get(CGM.IntTy, 0);
342     bool AnyDifferent = false;
343     for (const auto &I : SrcRD->vbases()) {
344       const CXXRecordDecl *VBase = I.getType()->getAsCXXRecordDecl();
345       if (!DstRD->isVirtuallyDerivedFrom(VBase))
346         continue;
347 
348       unsigned SrcVBIndex = VTContext.getVBTableIndex(SrcRD, VBase);
349       unsigned DstVBIndex = VTContext.getVBTableIndex(DstRD, VBase);
350       Map[SrcVBIndex] = llvm::ConstantInt::get(CGM.IntTy, DstVBIndex * 4);
351       AnyDifferent |= SrcVBIndex != DstVBIndex;
352     }
353     // This map would be useless, don't use it.
354     if (!AnyDifferent)
355       return nullptr;
356 
357     llvm::ArrayType *VDispMapTy = llvm::ArrayType::get(CGM.IntTy, Map.size());
358     llvm::Constant *Init = llvm::ConstantArray::get(VDispMapTy, Map);
359     llvm::GlobalValue::LinkageTypes Linkage =
360         SrcRD->isExternallyVisible() && DstRD->isExternallyVisible()
361             ? llvm::GlobalValue::LinkOnceODRLinkage
362             : llvm::GlobalValue::InternalLinkage;
363     auto *VDispMap = new llvm::GlobalVariable(
364         CGM.getModule(), VDispMapTy, /*isConstant=*/true, Linkage,
365         /*Initializer=*/Init, MangledName);
366     return VDispMap;
367   }
368 
369   void emitVBTableDefinition(const VPtrInfo &VBT, const CXXRecordDecl *RD,
370                              llvm::GlobalVariable *GV) const;
371 
372   void setThunkLinkage(llvm::Function *Thunk, bool ForVTable,
373                        GlobalDecl GD, bool ReturnAdjustment) override {
374     GVALinkage Linkage =
375         getContext().GetGVALinkageForFunction(cast<FunctionDecl>(GD.getDecl()));
376 
377     if (Linkage == GVA_Internal)
378       Thunk->setLinkage(llvm::GlobalValue::InternalLinkage);
379     else if (ReturnAdjustment)
380       Thunk->setLinkage(llvm::GlobalValue::WeakODRLinkage);
381     else
382       Thunk->setLinkage(llvm::GlobalValue::LinkOnceODRLinkage);
383   }
384 
385   bool exportThunk() override { return false; }
386 
387   llvm::Value *performThisAdjustment(CodeGenFunction &CGF, Address This,
388                                      const ThisAdjustment &TA) override;
389 
390   llvm::Value *performReturnAdjustment(CodeGenFunction &CGF, Address Ret,
391                                        const ReturnAdjustment &RA) override;
392 
393   void EmitThreadLocalInitFuncs(
394       CodeGenModule &CGM, ArrayRef<const VarDecl *> CXXThreadLocals,
395       ArrayRef<llvm::Function *> CXXThreadLocalInits,
396       ArrayRef<const VarDecl *> CXXThreadLocalInitVars) override;
397 
398   bool usesThreadWrapperFunction(const VarDecl *VD) const override {
399     return false;
400   }
401   LValue EmitThreadLocalVarDeclLValue(CodeGenFunction &CGF, const VarDecl *VD,
402                                       QualType LValType) override;
403 
404   void EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D,
405                        llvm::GlobalVariable *DeclPtr,
406                        bool PerformInit) override;
407   void registerGlobalDtor(CodeGenFunction &CGF, const VarDecl &D,
408                           llvm::FunctionCallee Dtor,
409                           llvm::Constant *Addr) override;
410 
411   // ==== Notes on array cookies =========
412   //
413   // MSVC seems to only use cookies when the class has a destructor; a
414   // two-argument usual array deallocation function isn't sufficient.
415   //
416   // For example, this code prints "100" and "1":
417   //   struct A {
418   //     char x;
419   //     void *operator new[](size_t sz) {
420   //       printf("%u\n", sz);
421   //       return malloc(sz);
422   //     }
423   //     void operator delete[](void *p, size_t sz) {
424   //       printf("%u\n", sz);
425   //       free(p);
426   //     }
427   //   };
428   //   int main() {
429   //     A *p = new A[100];
430   //     delete[] p;
431   //   }
432   // Whereas it prints "104" and "104" if you give A a destructor.
433 
434   bool requiresArrayCookie(const CXXDeleteExpr *expr,
435                            QualType elementType) override;
436   bool requiresArrayCookie(const CXXNewExpr *expr) override;
437   CharUnits getArrayCookieSizeImpl(QualType type) override;
438   Address InitializeArrayCookie(CodeGenFunction &CGF,
439                                 Address NewPtr,
440                                 llvm::Value *NumElements,
441                                 const CXXNewExpr *expr,
442                                 QualType ElementType) override;
443   llvm::Value *readArrayCookieImpl(CodeGenFunction &CGF,
444                                    Address allocPtr,
445                                    CharUnits cookieSize) override;
446 
447   friend struct MSRTTIBuilder;
448 
449   bool isImageRelative() const {
450     return CGM.getTarget().getPointerWidth(/*AddrSpace=*/0) == 64;
451   }
452 
453   // 5 routines for constructing the llvm types for MS RTTI structs.
454   llvm::StructType *getTypeDescriptorType(StringRef TypeInfoString) {
455     llvm::SmallString<32> TDTypeName("rtti.TypeDescriptor");
456     TDTypeName += llvm::utostr(TypeInfoString.size());
457     llvm::StructType *&TypeDescriptorType =
458         TypeDescriptorTypeMap[TypeInfoString.size()];
459     if (TypeDescriptorType)
460       return TypeDescriptorType;
461     llvm::Type *FieldTypes[] = {
462         CGM.Int8PtrPtrTy,
463         CGM.Int8PtrTy,
464         llvm::ArrayType::get(CGM.Int8Ty, TypeInfoString.size() + 1)};
465     TypeDescriptorType =
466         llvm::StructType::create(CGM.getLLVMContext(), FieldTypes, TDTypeName);
467     return TypeDescriptorType;
468   }
469 
470   llvm::Type *getImageRelativeType(llvm::Type *PtrType) {
471     if (!isImageRelative())
472       return PtrType;
473     return CGM.IntTy;
474   }
475 
476   llvm::StructType *getBaseClassDescriptorType() {
477     if (BaseClassDescriptorType)
478       return BaseClassDescriptorType;
479     llvm::Type *FieldTypes[] = {
480         getImageRelativeType(CGM.Int8PtrTy),
481         CGM.IntTy,
482         CGM.IntTy,
483         CGM.IntTy,
484         CGM.IntTy,
485         CGM.IntTy,
486         getImageRelativeType(getClassHierarchyDescriptorType()->getPointerTo()),
487     };
488     BaseClassDescriptorType = llvm::StructType::create(
489         CGM.getLLVMContext(), FieldTypes, "rtti.BaseClassDescriptor");
490     return BaseClassDescriptorType;
491   }
492 
493   llvm::StructType *getClassHierarchyDescriptorType() {
494     if (ClassHierarchyDescriptorType)
495       return ClassHierarchyDescriptorType;
496     // Forward-declare RTTIClassHierarchyDescriptor to break a cycle.
497     ClassHierarchyDescriptorType = llvm::StructType::create(
498         CGM.getLLVMContext(), "rtti.ClassHierarchyDescriptor");
499     llvm::Type *FieldTypes[] = {
500         CGM.IntTy,
501         CGM.IntTy,
502         CGM.IntTy,
503         getImageRelativeType(
504             getBaseClassDescriptorType()->getPointerTo()->getPointerTo()),
505     };
506     ClassHierarchyDescriptorType->setBody(FieldTypes);
507     return ClassHierarchyDescriptorType;
508   }
509 
510   llvm::StructType *getCompleteObjectLocatorType() {
511     if (CompleteObjectLocatorType)
512       return CompleteObjectLocatorType;
513     CompleteObjectLocatorType = llvm::StructType::create(
514         CGM.getLLVMContext(), "rtti.CompleteObjectLocator");
515     llvm::Type *FieldTypes[] = {
516         CGM.IntTy,
517         CGM.IntTy,
518         CGM.IntTy,
519         getImageRelativeType(CGM.Int8PtrTy),
520         getImageRelativeType(getClassHierarchyDescriptorType()->getPointerTo()),
521         getImageRelativeType(CompleteObjectLocatorType),
522     };
523     llvm::ArrayRef<llvm::Type *> FieldTypesRef(FieldTypes);
524     if (!isImageRelative())
525       FieldTypesRef = FieldTypesRef.drop_back();
526     CompleteObjectLocatorType->setBody(FieldTypesRef);
527     return CompleteObjectLocatorType;
528   }
529 
530   llvm::GlobalVariable *getImageBase() {
531     StringRef Name = "__ImageBase";
532     if (llvm::GlobalVariable *GV = CGM.getModule().getNamedGlobal(Name))
533       return GV;
534 
535     auto *GV = new llvm::GlobalVariable(CGM.getModule(), CGM.Int8Ty,
536                                         /*isConstant=*/true,
537                                         llvm::GlobalValue::ExternalLinkage,
538                                         /*Initializer=*/nullptr, Name);
539     CGM.setDSOLocal(GV);
540     return GV;
541   }
542 
543   llvm::Constant *getImageRelativeConstant(llvm::Constant *PtrVal) {
544     if (!isImageRelative())
545       return PtrVal;
546 
547     if (PtrVal->isNullValue())
548       return llvm::Constant::getNullValue(CGM.IntTy);
549 
550     llvm::Constant *ImageBaseAsInt =
551         llvm::ConstantExpr::getPtrToInt(getImageBase(), CGM.IntPtrTy);
552     llvm::Constant *PtrValAsInt =
553         llvm::ConstantExpr::getPtrToInt(PtrVal, CGM.IntPtrTy);
554     llvm::Constant *Diff =
555         llvm::ConstantExpr::getSub(PtrValAsInt, ImageBaseAsInt,
556                                    /*HasNUW=*/true, /*HasNSW=*/true);
557     return llvm::ConstantExpr::getTrunc(Diff, CGM.IntTy);
558   }
559 
560 private:
561   MicrosoftMangleContext &getMangleContext() {
562     return cast<MicrosoftMangleContext>(CodeGen::CGCXXABI::getMangleContext());
563   }
564 
565   llvm::Constant *getZeroInt() {
566     return llvm::ConstantInt::get(CGM.IntTy, 0);
567   }
568 
569   llvm::Constant *getAllOnesInt() {
570     return  llvm::Constant::getAllOnesValue(CGM.IntTy);
571   }
572 
573   CharUnits getVirtualFunctionPrologueThisAdjustment(GlobalDecl GD) override;
574 
575   void
576   GetNullMemberPointerFields(const MemberPointerType *MPT,
577                              llvm::SmallVectorImpl<llvm::Constant *> &fields);
578 
579   /// Shared code for virtual base adjustment.  Returns the offset from
580   /// the vbptr to the virtual base.  Optionally returns the address of the
581   /// vbptr itself.
582   llvm::Value *GetVBaseOffsetFromVBPtr(CodeGenFunction &CGF,
583                                        Address Base,
584                                        llvm::Value *VBPtrOffset,
585                                        llvm::Value *VBTableOffset,
586                                        llvm::Value **VBPtr = nullptr);
587 
588   llvm::Value *GetVBaseOffsetFromVBPtr(CodeGenFunction &CGF,
589                                        Address Base,
590                                        int32_t VBPtrOffset,
591                                        int32_t VBTableOffset,
592                                        llvm::Value **VBPtr = nullptr) {
593     assert(VBTableOffset % 4 == 0 && "should be byte offset into table of i32s");
594     llvm::Value *VBPOffset = llvm::ConstantInt::get(CGM.IntTy, VBPtrOffset),
595                 *VBTOffset = llvm::ConstantInt::get(CGM.IntTy, VBTableOffset);
596     return GetVBaseOffsetFromVBPtr(CGF, Base, VBPOffset, VBTOffset, VBPtr);
597   }
598 
599   std::tuple<Address, llvm::Value *, const CXXRecordDecl *>
600   performBaseAdjustment(CodeGenFunction &CGF, Address Value,
601                         QualType SrcRecordTy);
602 
603   /// Performs a full virtual base adjustment.  Used to dereference
604   /// pointers to members of virtual bases.
605   llvm::Value *AdjustVirtualBase(CodeGenFunction &CGF, const Expr *E,
606                                  const CXXRecordDecl *RD, Address Base,
607                                  llvm::Value *VirtualBaseAdjustmentOffset,
608                                  llvm::Value *VBPtrOffset /* optional */);
609 
610   /// Emits a full member pointer with the fields common to data and
611   /// function member pointers.
612   llvm::Constant *EmitFullMemberPointer(llvm::Constant *FirstField,
613                                         bool IsMemberFunction,
614                                         const CXXRecordDecl *RD,
615                                         CharUnits NonVirtualBaseAdjustment,
616                                         unsigned VBTableIndex);
617 
618   bool MemberPointerConstantIsNull(const MemberPointerType *MPT,
619                                    llvm::Constant *MP);
620 
621   /// - Initialize all vbptrs of 'this' with RD as the complete type.
622   void EmitVBPtrStores(CodeGenFunction &CGF, const CXXRecordDecl *RD);
623 
624   /// Caching wrapper around VBTableBuilder::enumerateVBTables().
625   const VBTableGlobals &enumerateVBTables(const CXXRecordDecl *RD);
626 
627   /// Generate a thunk for calling a virtual member function MD.
628   llvm::Function *EmitVirtualMemPtrThunk(const CXXMethodDecl *MD,
629                                          const MethodVFTableLocation &ML);
630 
631   llvm::Constant *EmitMemberDataPointer(const CXXRecordDecl *RD,
632                                         CharUnits offset);
633 
634 public:
635   llvm::Type *ConvertMemberPointerType(const MemberPointerType *MPT) override;
636 
637   bool isZeroInitializable(const MemberPointerType *MPT) override;
638 
639   bool isMemberPointerConvertible(const MemberPointerType *MPT) const override {
640     const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();
641     return RD->hasAttr<MSInheritanceAttr>();
642   }
643 
644   llvm::Constant *EmitNullMemberPointer(const MemberPointerType *MPT) override;
645 
646   llvm::Constant *EmitMemberDataPointer(const MemberPointerType *MPT,
647                                         CharUnits offset) override;
648   llvm::Constant *EmitMemberFunctionPointer(const CXXMethodDecl *MD) override;
649   llvm::Constant *EmitMemberPointer(const APValue &MP, QualType MPT) override;
650 
651   llvm::Value *EmitMemberPointerComparison(CodeGenFunction &CGF,
652                                            llvm::Value *L,
653                                            llvm::Value *R,
654                                            const MemberPointerType *MPT,
655                                            bool Inequality) override;
656 
657   llvm::Value *EmitMemberPointerIsNotNull(CodeGenFunction &CGF,
658                                           llvm::Value *MemPtr,
659                                           const MemberPointerType *MPT) override;
660 
661   llvm::Value *
662   EmitMemberDataPointerAddress(CodeGenFunction &CGF, const Expr *E,
663                                Address Base, llvm::Value *MemPtr,
664                                const MemberPointerType *MPT) override;
665 
666   llvm::Value *EmitNonNullMemberPointerConversion(
667       const MemberPointerType *SrcTy, const MemberPointerType *DstTy,
668       CastKind CK, CastExpr::path_const_iterator PathBegin,
669       CastExpr::path_const_iterator PathEnd, llvm::Value *Src,
670       CGBuilderTy &Builder);
671 
672   llvm::Value *EmitMemberPointerConversion(CodeGenFunction &CGF,
673                                            const CastExpr *E,
674                                            llvm::Value *Src) override;
675 
676   llvm::Constant *EmitMemberPointerConversion(const CastExpr *E,
677                                               llvm::Constant *Src) override;
678 
679   llvm::Constant *EmitMemberPointerConversion(
680       const MemberPointerType *SrcTy, const MemberPointerType *DstTy,
681       CastKind CK, CastExpr::path_const_iterator PathBegin,
682       CastExpr::path_const_iterator PathEnd, llvm::Constant *Src);
683 
684   CGCallee
685   EmitLoadOfMemberFunctionPointer(CodeGenFunction &CGF, const Expr *E,
686                                   Address This, llvm::Value *&ThisPtrForCall,
687                                   llvm::Value *MemPtr,
688                                   const MemberPointerType *MPT) override;
689 
690   void emitCXXStructor(GlobalDecl GD) override;
691 
692   llvm::StructType *getCatchableTypeType() {
693     if (CatchableTypeType)
694       return CatchableTypeType;
695     llvm::Type *FieldTypes[] = {
696         CGM.IntTy,                           // Flags
697         getImageRelativeType(CGM.Int8PtrTy), // TypeDescriptor
698         CGM.IntTy,                           // NonVirtualAdjustment
699         CGM.IntTy,                           // OffsetToVBPtr
700         CGM.IntTy,                           // VBTableIndex
701         CGM.IntTy,                           // Size
702         getImageRelativeType(CGM.Int8PtrTy)  // CopyCtor
703     };
704     CatchableTypeType = llvm::StructType::create(
705         CGM.getLLVMContext(), FieldTypes, "eh.CatchableType");
706     return CatchableTypeType;
707   }
708 
709   llvm::StructType *getCatchableTypeArrayType(uint32_t NumEntries) {
710     llvm::StructType *&CatchableTypeArrayType =
711         CatchableTypeArrayTypeMap[NumEntries];
712     if (CatchableTypeArrayType)
713       return CatchableTypeArrayType;
714 
715     llvm::SmallString<23> CTATypeName("eh.CatchableTypeArray.");
716     CTATypeName += llvm::utostr(NumEntries);
717     llvm::Type *CTType =
718         getImageRelativeType(getCatchableTypeType()->getPointerTo());
719     llvm::Type *FieldTypes[] = {
720         CGM.IntTy,                               // NumEntries
721         llvm::ArrayType::get(CTType, NumEntries) // CatchableTypes
722     };
723     CatchableTypeArrayType =
724         llvm::StructType::create(CGM.getLLVMContext(), FieldTypes, CTATypeName);
725     return CatchableTypeArrayType;
726   }
727 
728   llvm::StructType *getThrowInfoType() {
729     if (ThrowInfoType)
730       return ThrowInfoType;
731     llvm::Type *FieldTypes[] = {
732         CGM.IntTy,                           // Flags
733         getImageRelativeType(CGM.Int8PtrTy), // CleanupFn
734         getImageRelativeType(CGM.Int8PtrTy), // ForwardCompat
735         getImageRelativeType(CGM.Int8PtrTy)  // CatchableTypeArray
736     };
737     ThrowInfoType = llvm::StructType::create(CGM.getLLVMContext(), FieldTypes,
738                                              "eh.ThrowInfo");
739     return ThrowInfoType;
740   }
741 
742   llvm::FunctionCallee getThrowFn() {
743     // _CxxThrowException is passed an exception object and a ThrowInfo object
744     // which describes the exception.
745     llvm::Type *Args[] = {CGM.Int8PtrTy, getThrowInfoType()->getPointerTo()};
746     llvm::FunctionType *FTy =
747         llvm::FunctionType::get(CGM.VoidTy, Args, /*isVarArg=*/false);
748     llvm::FunctionCallee Throw =
749         CGM.CreateRuntimeFunction(FTy, "_CxxThrowException");
750     // _CxxThrowException is stdcall on 32-bit x86 platforms.
751     if (CGM.getTarget().getTriple().getArch() == llvm::Triple::x86) {
752       if (auto *Fn = dyn_cast<llvm::Function>(Throw.getCallee()))
753         Fn->setCallingConv(llvm::CallingConv::X86_StdCall);
754     }
755     return Throw;
756   }
757 
758   llvm::Function *getAddrOfCXXCtorClosure(const CXXConstructorDecl *CD,
759                                           CXXCtorType CT);
760 
761   llvm::Constant *getCatchableType(QualType T,
762                                    uint32_t NVOffset = 0,
763                                    int32_t VBPtrOffset = -1,
764                                    uint32_t VBIndex = 0);
765 
766   llvm::GlobalVariable *getCatchableTypeArray(QualType T);
767 
768   llvm::GlobalVariable *getThrowInfo(QualType T) override;
769 
770   std::pair<llvm::Value *, const CXXRecordDecl *>
771   LoadVTablePtr(CodeGenFunction &CGF, Address This,
772                 const CXXRecordDecl *RD) override;
773 
774 private:
775   typedef std::pair<const CXXRecordDecl *, CharUnits> VFTableIdTy;
776   typedef llvm::DenseMap<VFTableIdTy, llvm::GlobalVariable *> VTablesMapTy;
777   typedef llvm::DenseMap<VFTableIdTy, llvm::GlobalValue *> VFTablesMapTy;
778   /// All the vftables that have been referenced.
779   VFTablesMapTy VFTablesMap;
780   VTablesMapTy VTablesMap;
781 
782   /// This set holds the record decls we've deferred vtable emission for.
783   llvm::SmallPtrSet<const CXXRecordDecl *, 4> DeferredVFTables;
784 
785 
786   /// All the vbtables which have been referenced.
787   llvm::DenseMap<const CXXRecordDecl *, VBTableGlobals> VBTablesMap;
788 
789   /// Info on the global variable used to guard initialization of static locals.
790   /// The BitIndex field is only used for externally invisible declarations.
791   struct GuardInfo {
792     GuardInfo() : Guard(nullptr), BitIndex(0) {}
793     llvm::GlobalVariable *Guard;
794     unsigned BitIndex;
795   };
796 
797   /// Map from DeclContext to the current guard variable.  We assume that the
798   /// AST is visited in source code order.
799   llvm::DenseMap<const DeclContext *, GuardInfo> GuardVariableMap;
800   llvm::DenseMap<const DeclContext *, GuardInfo> ThreadLocalGuardVariableMap;
801   llvm::DenseMap<const DeclContext *, unsigned> ThreadSafeGuardNumMap;
802 
803   llvm::DenseMap<size_t, llvm::StructType *> TypeDescriptorTypeMap;
804   llvm::StructType *BaseClassDescriptorType;
805   llvm::StructType *ClassHierarchyDescriptorType;
806   llvm::StructType *CompleteObjectLocatorType;
807 
808   llvm::DenseMap<QualType, llvm::GlobalVariable *> CatchableTypeArrays;
809 
810   llvm::StructType *CatchableTypeType;
811   llvm::DenseMap<uint32_t, llvm::StructType *> CatchableTypeArrayTypeMap;
812   llvm::StructType *ThrowInfoType;
813 };
814 
815 }
816 
817 CGCXXABI::RecordArgABI
818 MicrosoftCXXABI::getRecordArgABI(const CXXRecordDecl *RD) const {
819   switch (CGM.getTarget().getTriple().getArch()) {
820   default:
821     // FIXME: Implement for other architectures.
822     return RAA_Default;
823 
824   case llvm::Triple::thumb:
825     // Use the simple Itanium rules for now.
826     // FIXME: This is incompatible with MSVC for arguments with a dtor and no
827     // copy ctor.
828     return !RD->canPassInRegisters() ? RAA_Indirect : RAA_Default;
829 
830   case llvm::Triple::x86:
831     // All record arguments are passed in memory on x86.  Decide whether to
832     // construct the object directly in argument memory, or to construct the
833     // argument elsewhere and copy the bytes during the call.
834 
835     // If C++ prohibits us from making a copy, construct the arguments directly
836     // into argument memory.
837     if (!RD->canPassInRegisters())
838       return RAA_DirectInMemory;
839 
840     // Otherwise, construct the argument into a temporary and copy the bytes
841     // into the outgoing argument memory.
842     return RAA_Default;
843 
844   case llvm::Triple::x86_64:
845   case llvm::Triple::aarch64:
846     return !RD->canPassInRegisters() ? RAA_Indirect : RAA_Default;
847   }
848 
849   llvm_unreachable("invalid enum");
850 }
851 
852 void MicrosoftCXXABI::emitVirtualObjectDelete(CodeGenFunction &CGF,
853                                               const CXXDeleteExpr *DE,
854                                               Address Ptr,
855                                               QualType ElementType,
856                                               const CXXDestructorDecl *Dtor) {
857   // FIXME: Provide a source location here even though there's no
858   // CXXMemberCallExpr for dtor call.
859   bool UseGlobalDelete = DE->isGlobalDelete();
860   CXXDtorType DtorType = UseGlobalDelete ? Dtor_Complete : Dtor_Deleting;
861   llvm::Value *MDThis = EmitVirtualDestructorCall(CGF, Dtor, DtorType, Ptr, DE);
862   if (UseGlobalDelete)
863     CGF.EmitDeleteCall(DE->getOperatorDelete(), MDThis, ElementType);
864 }
865 
866 void MicrosoftCXXABI::emitRethrow(CodeGenFunction &CGF, bool isNoReturn) {
867   llvm::Value *Args[] = {
868       llvm::ConstantPointerNull::get(CGM.Int8PtrTy),
869       llvm::ConstantPointerNull::get(getThrowInfoType()->getPointerTo())};
870   llvm::FunctionCallee Fn = getThrowFn();
871   if (isNoReturn)
872     CGF.EmitNoreturnRuntimeCallOrInvoke(Fn, Args);
873   else
874     CGF.EmitRuntimeCallOrInvoke(Fn, Args);
875 }
876 
877 void MicrosoftCXXABI::emitBeginCatch(CodeGenFunction &CGF,
878                                      const CXXCatchStmt *S) {
879   // In the MS ABI, the runtime handles the copy, and the catch handler is
880   // responsible for destruction.
881   VarDecl *CatchParam = S->getExceptionDecl();
882   llvm::BasicBlock *CatchPadBB = CGF.Builder.GetInsertBlock();
883   llvm::CatchPadInst *CPI =
884       cast<llvm::CatchPadInst>(CatchPadBB->getFirstNonPHI());
885   CGF.CurrentFuncletPad = CPI;
886 
887   // If this is a catch-all or the catch parameter is unnamed, we don't need to
888   // emit an alloca to the object.
889   if (!CatchParam || !CatchParam->getDeclName()) {
890     CGF.EHStack.pushCleanup<CatchRetScope>(NormalCleanup, CPI);
891     return;
892   }
893 
894   CodeGenFunction::AutoVarEmission var = CGF.EmitAutoVarAlloca(*CatchParam);
895   CPI->setArgOperand(2, var.getObjectAddress(CGF).getPointer());
896   CGF.EHStack.pushCleanup<CatchRetScope>(NormalCleanup, CPI);
897   CGF.EmitAutoVarCleanups(var);
898 }
899 
900 /// We need to perform a generic polymorphic operation (like a typeid
901 /// or a cast), which requires an object with a vfptr.  Adjust the
902 /// address to point to an object with a vfptr.
903 std::tuple<Address, llvm::Value *, const CXXRecordDecl *>
904 MicrosoftCXXABI::performBaseAdjustment(CodeGenFunction &CGF, Address Value,
905                                        QualType SrcRecordTy) {
906   Value = CGF.Builder.CreateBitCast(Value, CGF.Int8PtrTy);
907   const CXXRecordDecl *SrcDecl = SrcRecordTy->getAsCXXRecordDecl();
908   const ASTContext &Context = getContext();
909 
910   // If the class itself has a vfptr, great.  This check implicitly
911   // covers non-virtual base subobjects: a class with its own virtual
912   // functions would be a candidate to be a primary base.
913   if (Context.getASTRecordLayout(SrcDecl).hasExtendableVFPtr())
914     return std::make_tuple(Value, llvm::ConstantInt::get(CGF.Int32Ty, 0),
915                            SrcDecl);
916 
917   // Okay, one of the vbases must have a vfptr, or else this isn't
918   // actually a polymorphic class.
919   const CXXRecordDecl *PolymorphicBase = nullptr;
920   for (auto &Base : SrcDecl->vbases()) {
921     const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
922     if (Context.getASTRecordLayout(BaseDecl).hasExtendableVFPtr()) {
923       PolymorphicBase = BaseDecl;
924       break;
925     }
926   }
927   assert(PolymorphicBase && "polymorphic class has no apparent vfptr?");
928 
929   llvm::Value *Offset =
930     GetVirtualBaseClassOffset(CGF, Value, SrcDecl, PolymorphicBase);
931   llvm::Value *Ptr = CGF.Builder.CreateInBoundsGEP(Value.getPointer(), Offset);
932   CharUnits VBaseAlign =
933     CGF.CGM.getVBaseAlignment(Value.getAlignment(), SrcDecl, PolymorphicBase);
934   return std::make_tuple(Address(Ptr, VBaseAlign), Offset, PolymorphicBase);
935 }
936 
937 bool MicrosoftCXXABI::shouldTypeidBeNullChecked(bool IsDeref,
938                                                 QualType SrcRecordTy) {
939   const CXXRecordDecl *SrcDecl = SrcRecordTy->getAsCXXRecordDecl();
940   return IsDeref &&
941          !getContext().getASTRecordLayout(SrcDecl).hasExtendableVFPtr();
942 }
943 
944 static llvm::CallBase *emitRTtypeidCall(CodeGenFunction &CGF,
945                                         llvm::Value *Argument) {
946   llvm::Type *ArgTypes[] = {CGF.Int8PtrTy};
947   llvm::FunctionType *FTy =
948       llvm::FunctionType::get(CGF.Int8PtrTy, ArgTypes, false);
949   llvm::Value *Args[] = {Argument};
950   llvm::FunctionCallee Fn = CGF.CGM.CreateRuntimeFunction(FTy, "__RTtypeid");
951   return CGF.EmitRuntimeCallOrInvoke(Fn, Args);
952 }
953 
954 void MicrosoftCXXABI::EmitBadTypeidCall(CodeGenFunction &CGF) {
955   llvm::CallBase *Call =
956       emitRTtypeidCall(CGF, llvm::Constant::getNullValue(CGM.VoidPtrTy));
957   Call->setDoesNotReturn();
958   CGF.Builder.CreateUnreachable();
959 }
960 
961 llvm::Value *MicrosoftCXXABI::EmitTypeid(CodeGenFunction &CGF,
962                                          QualType SrcRecordTy,
963                                          Address ThisPtr,
964                                          llvm::Type *StdTypeInfoPtrTy) {
965   std::tie(ThisPtr, std::ignore, std::ignore) =
966       performBaseAdjustment(CGF, ThisPtr, SrcRecordTy);
967   llvm::CallBase *Typeid = emitRTtypeidCall(CGF, ThisPtr.getPointer());
968   return CGF.Builder.CreateBitCast(Typeid, StdTypeInfoPtrTy);
969 }
970 
971 bool MicrosoftCXXABI::shouldDynamicCastCallBeNullChecked(bool SrcIsPtr,
972                                                          QualType SrcRecordTy) {
973   const CXXRecordDecl *SrcDecl = SrcRecordTy->getAsCXXRecordDecl();
974   return SrcIsPtr &&
975          !getContext().getASTRecordLayout(SrcDecl).hasExtendableVFPtr();
976 }
977 
978 llvm::Value *MicrosoftCXXABI::EmitDynamicCastCall(
979     CodeGenFunction &CGF, Address This, QualType SrcRecordTy,
980     QualType DestTy, QualType DestRecordTy, llvm::BasicBlock *CastEnd) {
981   llvm::Type *DestLTy = CGF.ConvertType(DestTy);
982 
983   llvm::Value *SrcRTTI =
984       CGF.CGM.GetAddrOfRTTIDescriptor(SrcRecordTy.getUnqualifiedType());
985   llvm::Value *DestRTTI =
986       CGF.CGM.GetAddrOfRTTIDescriptor(DestRecordTy.getUnqualifiedType());
987 
988   llvm::Value *Offset;
989   std::tie(This, Offset, std::ignore) =
990       performBaseAdjustment(CGF, This, SrcRecordTy);
991   llvm::Value *ThisPtr = This.getPointer();
992   Offset = CGF.Builder.CreateTrunc(Offset, CGF.Int32Ty);
993 
994   // PVOID __RTDynamicCast(
995   //   PVOID inptr,
996   //   LONG VfDelta,
997   //   PVOID SrcType,
998   //   PVOID TargetType,
999   //   BOOL isReference)
1000   llvm::Type *ArgTypes[] = {CGF.Int8PtrTy, CGF.Int32Ty, CGF.Int8PtrTy,
1001                             CGF.Int8PtrTy, CGF.Int32Ty};
1002   llvm::FunctionCallee Function = CGF.CGM.CreateRuntimeFunction(
1003       llvm::FunctionType::get(CGF.Int8PtrTy, ArgTypes, false),
1004       "__RTDynamicCast");
1005   llvm::Value *Args[] = {
1006       ThisPtr, Offset, SrcRTTI, DestRTTI,
1007       llvm::ConstantInt::get(CGF.Int32Ty, DestTy->isReferenceType())};
1008   ThisPtr = CGF.EmitRuntimeCallOrInvoke(Function, Args);
1009   return CGF.Builder.CreateBitCast(ThisPtr, DestLTy);
1010 }
1011 
1012 llvm::Value *
1013 MicrosoftCXXABI::EmitDynamicCastToVoid(CodeGenFunction &CGF, Address Value,
1014                                        QualType SrcRecordTy,
1015                                        QualType DestTy) {
1016   std::tie(Value, std::ignore, std::ignore) =
1017       performBaseAdjustment(CGF, Value, SrcRecordTy);
1018 
1019   // PVOID __RTCastToVoid(
1020   //   PVOID inptr)
1021   llvm::Type *ArgTypes[] = {CGF.Int8PtrTy};
1022   llvm::FunctionCallee Function = CGF.CGM.CreateRuntimeFunction(
1023       llvm::FunctionType::get(CGF.Int8PtrTy, ArgTypes, false),
1024       "__RTCastToVoid");
1025   llvm::Value *Args[] = {Value.getPointer()};
1026   return CGF.EmitRuntimeCall(Function, Args);
1027 }
1028 
1029 bool MicrosoftCXXABI::EmitBadCastCall(CodeGenFunction &CGF) {
1030   return false;
1031 }
1032 
1033 llvm::Value *MicrosoftCXXABI::GetVirtualBaseClassOffset(
1034     CodeGenFunction &CGF, Address This, const CXXRecordDecl *ClassDecl,
1035     const CXXRecordDecl *BaseClassDecl) {
1036   const ASTContext &Context = getContext();
1037   int64_t VBPtrChars =
1038       Context.getASTRecordLayout(ClassDecl).getVBPtrOffset().getQuantity();
1039   llvm::Value *VBPtrOffset = llvm::ConstantInt::get(CGM.PtrDiffTy, VBPtrChars);
1040   CharUnits IntSize = Context.getTypeSizeInChars(Context.IntTy);
1041   CharUnits VBTableChars =
1042       IntSize *
1043       CGM.getMicrosoftVTableContext().getVBTableIndex(ClassDecl, BaseClassDecl);
1044   llvm::Value *VBTableOffset =
1045       llvm::ConstantInt::get(CGM.IntTy, VBTableChars.getQuantity());
1046 
1047   llvm::Value *VBPtrToNewBase =
1048       GetVBaseOffsetFromVBPtr(CGF, This, VBPtrOffset, VBTableOffset);
1049   VBPtrToNewBase =
1050       CGF.Builder.CreateSExtOrBitCast(VBPtrToNewBase, CGM.PtrDiffTy);
1051   return CGF.Builder.CreateNSWAdd(VBPtrOffset, VBPtrToNewBase);
1052 }
1053 
1054 bool MicrosoftCXXABI::HasThisReturn(GlobalDecl GD) const {
1055   return isa<CXXConstructorDecl>(GD.getDecl());
1056 }
1057 
1058 static bool isDeletingDtor(GlobalDecl GD) {
1059   return isa<CXXDestructorDecl>(GD.getDecl()) &&
1060          GD.getDtorType() == Dtor_Deleting;
1061 }
1062 
1063 bool MicrosoftCXXABI::hasMostDerivedReturn(GlobalDecl GD) const {
1064   return isDeletingDtor(GD);
1065 }
1066 
1067 static bool IsSizeGreaterThan128(const CXXRecordDecl *RD) {
1068   return RD->getASTContext().getTypeSize(RD->getTypeForDecl()) > 128;
1069 }
1070 
1071 static bool hasMicrosoftABIRestrictions(const CXXRecordDecl *RD) {
1072   // For AArch64, we use the C++14 definition of an aggregate, so we also
1073   // check for:
1074   //   No private or protected non static data members.
1075   //   No base classes
1076   //   No virtual functions
1077   // Additionally, we need to ensure that there is a trivial copy assignment
1078   // operator, a trivial destructor and no user-provided constructors.
1079   if (RD->hasProtectedFields() || RD->hasPrivateFields())
1080     return true;
1081   if (RD->getNumBases() > 0)
1082     return true;
1083   if (RD->isPolymorphic())
1084     return true;
1085   if (RD->hasNonTrivialCopyAssignment())
1086     return true;
1087   for (const CXXConstructorDecl *Ctor : RD->ctors())
1088     if (Ctor->isUserProvided())
1089       return true;
1090   if (RD->hasNonTrivialDestructor())
1091     return true;
1092   return false;
1093 }
1094 
1095 bool MicrosoftCXXABI::classifyReturnType(CGFunctionInfo &FI) const {
1096   const CXXRecordDecl *RD = FI.getReturnType()->getAsCXXRecordDecl();
1097   if (!RD)
1098     return false;
1099 
1100   bool isAArch64 = CGM.getTarget().getTriple().isAArch64();
1101   bool isSimple = !isAArch64 || !hasMicrosoftABIRestrictions(RD);
1102   bool isIndirectReturn =
1103       isAArch64 ? (!RD->canPassInRegisters() ||
1104                    IsSizeGreaterThan128(RD))
1105                 : !RD->isPOD();
1106   bool isInstanceMethod = FI.isInstanceMethod();
1107 
1108   if (isIndirectReturn || !isSimple || isInstanceMethod) {
1109     CharUnits Align = CGM.getContext().getTypeAlignInChars(FI.getReturnType());
1110     FI.getReturnInfo() = ABIArgInfo::getIndirect(Align, /*ByVal=*/false);
1111     FI.getReturnInfo().setSRetAfterThis(isInstanceMethod);
1112 
1113     FI.getReturnInfo().setInReg(isAArch64 &&
1114                                 !(isSimple && IsSizeGreaterThan128(RD)));
1115 
1116     return true;
1117   }
1118 
1119   // Otherwise, use the C ABI rules.
1120   return false;
1121 }
1122 
1123 llvm::BasicBlock *
1124 MicrosoftCXXABI::EmitCtorCompleteObjectHandler(CodeGenFunction &CGF,
1125                                                const CXXRecordDecl *RD) {
1126   llvm::Value *IsMostDerivedClass = getStructorImplicitParamValue(CGF);
1127   assert(IsMostDerivedClass &&
1128          "ctor for a class with virtual bases must have an implicit parameter");
1129   llvm::Value *IsCompleteObject =
1130     CGF.Builder.CreateIsNotNull(IsMostDerivedClass, "is_complete_object");
1131 
1132   llvm::BasicBlock *CallVbaseCtorsBB = CGF.createBasicBlock("ctor.init_vbases");
1133   llvm::BasicBlock *SkipVbaseCtorsBB = CGF.createBasicBlock("ctor.skip_vbases");
1134   CGF.Builder.CreateCondBr(IsCompleteObject,
1135                            CallVbaseCtorsBB, SkipVbaseCtorsBB);
1136 
1137   CGF.EmitBlock(CallVbaseCtorsBB);
1138 
1139   // Fill in the vbtable pointers here.
1140   EmitVBPtrStores(CGF, RD);
1141 
1142   // CGF will put the base ctor calls in this basic block for us later.
1143 
1144   return SkipVbaseCtorsBB;
1145 }
1146 
1147 llvm::BasicBlock *
1148 MicrosoftCXXABI::EmitDtorCompleteObjectHandler(CodeGenFunction &CGF) {
1149   llvm::Value *IsMostDerivedClass = getStructorImplicitParamValue(CGF);
1150   assert(IsMostDerivedClass &&
1151          "ctor for a class with virtual bases must have an implicit parameter");
1152   llvm::Value *IsCompleteObject =
1153       CGF.Builder.CreateIsNotNull(IsMostDerivedClass, "is_complete_object");
1154 
1155   llvm::BasicBlock *CallVbaseDtorsBB = CGF.createBasicBlock("Dtor.dtor_vbases");
1156   llvm::BasicBlock *SkipVbaseDtorsBB = CGF.createBasicBlock("Dtor.skip_vbases");
1157   CGF.Builder.CreateCondBr(IsCompleteObject,
1158                            CallVbaseDtorsBB, SkipVbaseDtorsBB);
1159 
1160   CGF.EmitBlock(CallVbaseDtorsBB);
1161   // CGF will put the base dtor calls in this basic block for us later.
1162 
1163   return SkipVbaseDtorsBB;
1164 }
1165 
1166 void MicrosoftCXXABI::initializeHiddenVirtualInheritanceMembers(
1167     CodeGenFunction &CGF, const CXXRecordDecl *RD) {
1168   // In most cases, an override for a vbase virtual method can adjust
1169   // the "this" parameter by applying a constant offset.
1170   // However, this is not enough while a constructor or a destructor of some
1171   // class X is being executed if all the following conditions are met:
1172   //  - X has virtual bases, (1)
1173   //  - X overrides a virtual method M of a vbase Y, (2)
1174   //  - X itself is a vbase of the most derived class.
1175   //
1176   // If (1) and (2) are true, the vtorDisp for vbase Y is a hidden member of X
1177   // which holds the extra amount of "this" adjustment we must do when we use
1178   // the X vftables (i.e. during X ctor or dtor).
1179   // Outside the ctors and dtors, the values of vtorDisps are zero.
1180 
1181   const ASTRecordLayout &Layout = getContext().getASTRecordLayout(RD);
1182   typedef ASTRecordLayout::VBaseOffsetsMapTy VBOffsets;
1183   const VBOffsets &VBaseMap = Layout.getVBaseOffsetsMap();
1184   CGBuilderTy &Builder = CGF.Builder;
1185 
1186   unsigned AS = getThisAddress(CGF).getAddressSpace();
1187   llvm::Value *Int8This = nullptr;  // Initialize lazily.
1188 
1189   for (const CXXBaseSpecifier &S : RD->vbases()) {
1190     const CXXRecordDecl *VBase = S.getType()->getAsCXXRecordDecl();
1191     auto I = VBaseMap.find(VBase);
1192     assert(I != VBaseMap.end());
1193     if (!I->second.hasVtorDisp())
1194       continue;
1195 
1196     llvm::Value *VBaseOffset =
1197         GetVirtualBaseClassOffset(CGF, getThisAddress(CGF), RD, VBase);
1198     uint64_t ConstantVBaseOffset = I->second.VBaseOffset.getQuantity();
1199 
1200     // vtorDisp_for_vbase = vbptr[vbase_idx] - offsetof(RD, vbase).
1201     llvm::Value *VtorDispValue = Builder.CreateSub(
1202         VBaseOffset, llvm::ConstantInt::get(CGM.PtrDiffTy, ConstantVBaseOffset),
1203         "vtordisp.value");
1204     VtorDispValue = Builder.CreateTruncOrBitCast(VtorDispValue, CGF.Int32Ty);
1205 
1206     if (!Int8This)
1207       Int8This = Builder.CreateBitCast(getThisValue(CGF),
1208                                        CGF.Int8Ty->getPointerTo(AS));
1209     llvm::Value *VtorDispPtr = Builder.CreateInBoundsGEP(Int8This, VBaseOffset);
1210     // vtorDisp is always the 32-bits before the vbase in the class layout.
1211     VtorDispPtr = Builder.CreateConstGEP1_32(VtorDispPtr, -4);
1212     VtorDispPtr = Builder.CreateBitCast(
1213         VtorDispPtr, CGF.Int32Ty->getPointerTo(AS), "vtordisp.ptr");
1214 
1215     Builder.CreateAlignedStore(VtorDispValue, VtorDispPtr,
1216                                CharUnits::fromQuantity(4));
1217   }
1218 }
1219 
1220 static bool hasDefaultCXXMethodCC(ASTContext &Context,
1221                                   const CXXMethodDecl *MD) {
1222   CallingConv ExpectedCallingConv = Context.getDefaultCallingConvention(
1223       /*IsVariadic=*/false, /*IsCXXMethod=*/true);
1224   CallingConv ActualCallingConv =
1225       MD->getType()->castAs<FunctionProtoType>()->getCallConv();
1226   return ExpectedCallingConv == ActualCallingConv;
1227 }
1228 
1229 void MicrosoftCXXABI::EmitCXXConstructors(const CXXConstructorDecl *D) {
1230   // There's only one constructor type in this ABI.
1231   CGM.EmitGlobal(GlobalDecl(D, Ctor_Complete));
1232 
1233   // Exported default constructors either have a simple call-site where they use
1234   // the typical calling convention and have a single 'this' pointer for an
1235   // argument -or- they get a wrapper function which appropriately thunks to the
1236   // real default constructor.  This thunk is the default constructor closure.
1237   if (D->hasAttr<DLLExportAttr>() && D->isDefaultConstructor())
1238     if (!hasDefaultCXXMethodCC(getContext(), D) || D->getNumParams() != 0) {
1239       llvm::Function *Fn = getAddrOfCXXCtorClosure(D, Ctor_DefaultClosure);
1240       Fn->setLinkage(llvm::GlobalValue::WeakODRLinkage);
1241       CGM.setGVProperties(Fn, D);
1242     }
1243 }
1244 
1245 void MicrosoftCXXABI::EmitVBPtrStores(CodeGenFunction &CGF,
1246                                       const CXXRecordDecl *RD) {
1247   Address This = getThisAddress(CGF);
1248   This = CGF.Builder.CreateElementBitCast(This, CGM.Int8Ty, "this.int8");
1249   const ASTContext &Context = getContext();
1250   const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
1251 
1252   const VBTableGlobals &VBGlobals = enumerateVBTables(RD);
1253   for (unsigned I = 0, E = VBGlobals.VBTables->size(); I != E; ++I) {
1254     const std::unique_ptr<VPtrInfo> &VBT = (*VBGlobals.VBTables)[I];
1255     llvm::GlobalVariable *GV = VBGlobals.Globals[I];
1256     const ASTRecordLayout &SubobjectLayout =
1257         Context.getASTRecordLayout(VBT->IntroducingObject);
1258     CharUnits Offs = VBT->NonVirtualOffset;
1259     Offs += SubobjectLayout.getVBPtrOffset();
1260     if (VBT->getVBaseWithVPtr())
1261       Offs += Layout.getVBaseClassOffset(VBT->getVBaseWithVPtr());
1262     Address VBPtr = CGF.Builder.CreateConstInBoundsByteGEP(This, Offs);
1263     llvm::Value *GVPtr =
1264         CGF.Builder.CreateConstInBoundsGEP2_32(GV->getValueType(), GV, 0, 0);
1265     VBPtr = CGF.Builder.CreateElementBitCast(VBPtr, GVPtr->getType(),
1266                                       "vbptr." + VBT->ObjectWithVPtr->getName());
1267     CGF.Builder.CreateStore(GVPtr, VBPtr);
1268   }
1269 }
1270 
1271 CGCXXABI::AddedStructorArgCounts
1272 MicrosoftCXXABI::buildStructorSignature(GlobalDecl GD,
1273                                         SmallVectorImpl<CanQualType> &ArgTys) {
1274   AddedStructorArgCounts Added;
1275   // TODO: 'for base' flag
1276   if (isa<CXXDestructorDecl>(GD.getDecl()) &&
1277       GD.getDtorType() == Dtor_Deleting) {
1278     // The scalar deleting destructor takes an implicit int parameter.
1279     ArgTys.push_back(getContext().IntTy);
1280     ++Added.Suffix;
1281   }
1282   auto *CD = dyn_cast<CXXConstructorDecl>(GD.getDecl());
1283   if (!CD)
1284     return Added;
1285 
1286   // All parameters are already in place except is_most_derived, which goes
1287   // after 'this' if it's variadic and last if it's not.
1288 
1289   const CXXRecordDecl *Class = CD->getParent();
1290   const FunctionProtoType *FPT = CD->getType()->castAs<FunctionProtoType>();
1291   if (Class->getNumVBases()) {
1292     if (FPT->isVariadic()) {
1293       ArgTys.insert(ArgTys.begin() + 1, getContext().IntTy);
1294       ++Added.Prefix;
1295     } else {
1296       ArgTys.push_back(getContext().IntTy);
1297       ++Added.Suffix;
1298     }
1299   }
1300 
1301   return Added;
1302 }
1303 
1304 void MicrosoftCXXABI::setCXXDestructorDLLStorage(llvm::GlobalValue *GV,
1305                                                  const CXXDestructorDecl *Dtor,
1306                                                  CXXDtorType DT) const {
1307   // Deleting destructor variants are never imported or exported. Give them the
1308   // default storage class.
1309   if (DT == Dtor_Deleting) {
1310     GV->setDLLStorageClass(llvm::GlobalValue::DefaultStorageClass);
1311   } else {
1312     const NamedDecl *ND = Dtor;
1313     CGM.setDLLImportDLLExport(GV, ND);
1314   }
1315 }
1316 
1317 llvm::GlobalValue::LinkageTypes MicrosoftCXXABI::getCXXDestructorLinkage(
1318     GVALinkage Linkage, const CXXDestructorDecl *Dtor, CXXDtorType DT) const {
1319   // Internal things are always internal, regardless of attributes. After this,
1320   // we know the thunk is externally visible.
1321   if (Linkage == GVA_Internal)
1322     return llvm::GlobalValue::InternalLinkage;
1323 
1324   switch (DT) {
1325   case Dtor_Base:
1326     // The base destructor most closely tracks the user-declared constructor, so
1327     // we delegate back to the normal declarator case.
1328     return CGM.getLLVMLinkageForDeclarator(Dtor, Linkage,
1329                                            /*IsConstantVariable=*/false);
1330   case Dtor_Complete:
1331     // The complete destructor is like an inline function, but it may be
1332     // imported and therefore must be exported as well. This requires changing
1333     // the linkage if a DLL attribute is present.
1334     if (Dtor->hasAttr<DLLExportAttr>())
1335       return llvm::GlobalValue::WeakODRLinkage;
1336     if (Dtor->hasAttr<DLLImportAttr>())
1337       return llvm::GlobalValue::AvailableExternallyLinkage;
1338     return llvm::GlobalValue::LinkOnceODRLinkage;
1339   case Dtor_Deleting:
1340     // Deleting destructors are like inline functions. They have vague linkage
1341     // and are emitted everywhere they are used. They are internal if the class
1342     // is internal.
1343     return llvm::GlobalValue::LinkOnceODRLinkage;
1344   case Dtor_Comdat:
1345     llvm_unreachable("MS C++ ABI does not support comdat dtors");
1346   }
1347   llvm_unreachable("invalid dtor type");
1348 }
1349 
1350 void MicrosoftCXXABI::EmitCXXDestructors(const CXXDestructorDecl *D) {
1351   // The TU defining a dtor is only guaranteed to emit a base destructor.  All
1352   // other destructor variants are delegating thunks.
1353   CGM.EmitGlobal(GlobalDecl(D, Dtor_Base));
1354 
1355   // If the class is dllexported, emit the complete (vbase) destructor wherever
1356   // the base dtor is emitted.
1357   // FIXME: To match MSVC, this should only be done when the class is exported
1358   // with -fdllexport-inlines enabled.
1359   if (D->getParent()->getNumVBases() > 0 && D->hasAttr<DLLExportAttr>())
1360     CGM.EmitGlobal(GlobalDecl(D, Dtor_Complete));
1361 }
1362 
1363 CharUnits
1364 MicrosoftCXXABI::getVirtualFunctionPrologueThisAdjustment(GlobalDecl GD) {
1365   const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
1366 
1367   if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
1368     // Complete destructors take a pointer to the complete object as a
1369     // parameter, thus don't need this adjustment.
1370     if (GD.getDtorType() == Dtor_Complete)
1371       return CharUnits();
1372 
1373     // There's no Dtor_Base in vftable but it shares the this adjustment with
1374     // the deleting one, so look it up instead.
1375     GD = GlobalDecl(DD, Dtor_Deleting);
1376   }
1377 
1378   MethodVFTableLocation ML =
1379       CGM.getMicrosoftVTableContext().getMethodVFTableLocation(GD);
1380   CharUnits Adjustment = ML.VFPtrOffset;
1381 
1382   // Normal virtual instance methods need to adjust from the vfptr that first
1383   // defined the virtual method to the virtual base subobject, but destructors
1384   // do not.  The vector deleting destructor thunk applies this adjustment for
1385   // us if necessary.
1386   if (isa<CXXDestructorDecl>(MD))
1387     Adjustment = CharUnits::Zero();
1388 
1389   if (ML.VBase) {
1390     const ASTRecordLayout &DerivedLayout =
1391         getContext().getASTRecordLayout(MD->getParent());
1392     Adjustment += DerivedLayout.getVBaseClassOffset(ML.VBase);
1393   }
1394 
1395   return Adjustment;
1396 }
1397 
1398 Address MicrosoftCXXABI::adjustThisArgumentForVirtualFunctionCall(
1399     CodeGenFunction &CGF, GlobalDecl GD, Address This,
1400     bool VirtualCall) {
1401   if (!VirtualCall) {
1402     // If the call of a virtual function is not virtual, we just have to
1403     // compensate for the adjustment the virtual function does in its prologue.
1404     CharUnits Adjustment = getVirtualFunctionPrologueThisAdjustment(GD);
1405     if (Adjustment.isZero())
1406       return This;
1407 
1408     This = CGF.Builder.CreateElementBitCast(This, CGF.Int8Ty);
1409     assert(Adjustment.isPositive());
1410     return CGF.Builder.CreateConstByteGEP(This, Adjustment);
1411   }
1412 
1413   const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
1414 
1415   GlobalDecl LookupGD = GD;
1416   if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
1417     // Complete dtors take a pointer to the complete object,
1418     // thus don't need adjustment.
1419     if (GD.getDtorType() == Dtor_Complete)
1420       return This;
1421 
1422     // There's only Dtor_Deleting in vftable but it shares the this adjustment
1423     // with the base one, so look up the deleting one instead.
1424     LookupGD = GlobalDecl(DD, Dtor_Deleting);
1425   }
1426   MethodVFTableLocation ML =
1427       CGM.getMicrosoftVTableContext().getMethodVFTableLocation(LookupGD);
1428 
1429   CharUnits StaticOffset = ML.VFPtrOffset;
1430 
1431   // Base destructors expect 'this' to point to the beginning of the base
1432   // subobject, not the first vfptr that happens to contain the virtual dtor.
1433   // However, we still need to apply the virtual base adjustment.
1434   if (isa<CXXDestructorDecl>(MD) && GD.getDtorType() == Dtor_Base)
1435     StaticOffset = CharUnits::Zero();
1436 
1437   Address Result = This;
1438   if (ML.VBase) {
1439     Result = CGF.Builder.CreateElementBitCast(Result, CGF.Int8Ty);
1440 
1441     const CXXRecordDecl *Derived = MD->getParent();
1442     const CXXRecordDecl *VBase = ML.VBase;
1443     llvm::Value *VBaseOffset =
1444       GetVirtualBaseClassOffset(CGF, Result, Derived, VBase);
1445     llvm::Value *VBasePtr =
1446       CGF.Builder.CreateInBoundsGEP(Result.getPointer(), VBaseOffset);
1447     CharUnits VBaseAlign =
1448       CGF.CGM.getVBaseAlignment(Result.getAlignment(), Derived, VBase);
1449     Result = Address(VBasePtr, VBaseAlign);
1450   }
1451   if (!StaticOffset.isZero()) {
1452     assert(StaticOffset.isPositive());
1453     Result = CGF.Builder.CreateElementBitCast(Result, CGF.Int8Ty);
1454     if (ML.VBase) {
1455       // Non-virtual adjustment might result in a pointer outside the allocated
1456       // object, e.g. if the final overrider class is laid out after the virtual
1457       // base that declares a method in the most derived class.
1458       // FIXME: Update the code that emits this adjustment in thunks prologues.
1459       Result = CGF.Builder.CreateConstByteGEP(Result, StaticOffset);
1460     } else {
1461       Result = CGF.Builder.CreateConstInBoundsByteGEP(Result, StaticOffset);
1462     }
1463   }
1464   return Result;
1465 }
1466 
1467 void MicrosoftCXXABI::addImplicitStructorParams(CodeGenFunction &CGF,
1468                                                 QualType &ResTy,
1469                                                 FunctionArgList &Params) {
1470   ASTContext &Context = getContext();
1471   const CXXMethodDecl *MD = cast<CXXMethodDecl>(CGF.CurGD.getDecl());
1472   assert(isa<CXXConstructorDecl>(MD) || isa<CXXDestructorDecl>(MD));
1473   if (isa<CXXConstructorDecl>(MD) && MD->getParent()->getNumVBases()) {
1474     auto *IsMostDerived = ImplicitParamDecl::Create(
1475         Context, /*DC=*/nullptr, CGF.CurGD.getDecl()->getLocation(),
1476         &Context.Idents.get("is_most_derived"), Context.IntTy,
1477         ImplicitParamDecl::Other);
1478     // The 'most_derived' parameter goes second if the ctor is variadic and last
1479     // if it's not.  Dtors can't be variadic.
1480     const FunctionProtoType *FPT = MD->getType()->castAs<FunctionProtoType>();
1481     if (FPT->isVariadic())
1482       Params.insert(Params.begin() + 1, IsMostDerived);
1483     else
1484       Params.push_back(IsMostDerived);
1485     getStructorImplicitParamDecl(CGF) = IsMostDerived;
1486   } else if (isDeletingDtor(CGF.CurGD)) {
1487     auto *ShouldDelete = ImplicitParamDecl::Create(
1488         Context, /*DC=*/nullptr, CGF.CurGD.getDecl()->getLocation(),
1489         &Context.Idents.get("should_call_delete"), Context.IntTy,
1490         ImplicitParamDecl::Other);
1491     Params.push_back(ShouldDelete);
1492     getStructorImplicitParamDecl(CGF) = ShouldDelete;
1493   }
1494 }
1495 
1496 void MicrosoftCXXABI::EmitInstanceFunctionProlog(CodeGenFunction &CGF) {
1497   // Naked functions have no prolog.
1498   if (CGF.CurFuncDecl && CGF.CurFuncDecl->hasAttr<NakedAttr>())
1499     return;
1500 
1501   // Overridden virtual methods of non-primary bases need to adjust the incoming
1502   // 'this' pointer in the prologue. In this hierarchy, C::b will subtract
1503   // sizeof(void*) to adjust from B* to C*:
1504   //   struct A { virtual void a(); };
1505   //   struct B { virtual void b(); };
1506   //   struct C : A, B { virtual void b(); };
1507   //
1508   // Leave the value stored in the 'this' alloca unadjusted, so that the
1509   // debugger sees the unadjusted value. Microsoft debuggers require this, and
1510   // will apply the ThisAdjustment in the method type information.
1511   // FIXME: Do something better for DWARF debuggers, which won't expect this,
1512   // without making our codegen depend on debug info settings.
1513   llvm::Value *This = loadIncomingCXXThis(CGF);
1514   const CXXMethodDecl *MD = cast<CXXMethodDecl>(CGF.CurGD.getDecl());
1515   if (!CGF.CurFuncIsThunk && MD->isVirtual()) {
1516     CharUnits Adjustment = getVirtualFunctionPrologueThisAdjustment(CGF.CurGD);
1517     if (!Adjustment.isZero()) {
1518       unsigned AS = cast<llvm::PointerType>(This->getType())->getAddressSpace();
1519       llvm::Type *charPtrTy = CGF.Int8Ty->getPointerTo(AS),
1520                  *thisTy = This->getType();
1521       This = CGF.Builder.CreateBitCast(This, charPtrTy);
1522       assert(Adjustment.isPositive());
1523       This = CGF.Builder.CreateConstInBoundsGEP1_32(CGF.Int8Ty, This,
1524                                                     -Adjustment.getQuantity());
1525       This = CGF.Builder.CreateBitCast(This, thisTy, "this.adjusted");
1526     }
1527   }
1528   setCXXABIThisValue(CGF, This);
1529 
1530   // If this is a function that the ABI specifies returns 'this', initialize
1531   // the return slot to 'this' at the start of the function.
1532   //
1533   // Unlike the setting of return types, this is done within the ABI
1534   // implementation instead of by clients of CGCXXABI because:
1535   // 1) getThisValue is currently protected
1536   // 2) in theory, an ABI could implement 'this' returns some other way;
1537   //    HasThisReturn only specifies a contract, not the implementation
1538   if (HasThisReturn(CGF.CurGD))
1539     CGF.Builder.CreateStore(getThisValue(CGF), CGF.ReturnValue);
1540   else if (hasMostDerivedReturn(CGF.CurGD))
1541     CGF.Builder.CreateStore(CGF.EmitCastToVoidPtr(getThisValue(CGF)),
1542                             CGF.ReturnValue);
1543 
1544   if (isa<CXXConstructorDecl>(MD) && MD->getParent()->getNumVBases()) {
1545     assert(getStructorImplicitParamDecl(CGF) &&
1546            "no implicit parameter for a constructor with virtual bases?");
1547     getStructorImplicitParamValue(CGF)
1548       = CGF.Builder.CreateLoad(
1549           CGF.GetAddrOfLocalVar(getStructorImplicitParamDecl(CGF)),
1550           "is_most_derived");
1551   }
1552 
1553   if (isDeletingDtor(CGF.CurGD)) {
1554     assert(getStructorImplicitParamDecl(CGF) &&
1555            "no implicit parameter for a deleting destructor?");
1556     getStructorImplicitParamValue(CGF)
1557       = CGF.Builder.CreateLoad(
1558           CGF.GetAddrOfLocalVar(getStructorImplicitParamDecl(CGF)),
1559           "should_call_delete");
1560   }
1561 }
1562 
1563 CGCXXABI::AddedStructorArgs MicrosoftCXXABI::getImplicitConstructorArgs(
1564     CodeGenFunction &CGF, const CXXConstructorDecl *D, CXXCtorType Type,
1565     bool ForVirtualBase, bool Delegating) {
1566   assert(Type == Ctor_Complete || Type == Ctor_Base);
1567 
1568   // Check if we need a 'most_derived' parameter.
1569   if (!D->getParent()->getNumVBases())
1570     return AddedStructorArgs{};
1571 
1572   // Add the 'most_derived' argument second if we are variadic or last if not.
1573   const FunctionProtoType *FPT = D->getType()->castAs<FunctionProtoType>();
1574   llvm::Value *MostDerivedArg;
1575   if (Delegating) {
1576     MostDerivedArg = getStructorImplicitParamValue(CGF);
1577   } else {
1578     MostDerivedArg = llvm::ConstantInt::get(CGM.Int32Ty, Type == Ctor_Complete);
1579   }
1580   if (FPT->isVariadic()) {
1581     return AddedStructorArgs::prefix({{MostDerivedArg, getContext().IntTy}});
1582   }
1583   return AddedStructorArgs::suffix({{MostDerivedArg, getContext().IntTy}});
1584 }
1585 
1586 llvm::Value *MicrosoftCXXABI::getCXXDestructorImplicitParam(
1587     CodeGenFunction &CGF, const CXXDestructorDecl *DD, CXXDtorType Type,
1588     bool ForVirtualBase, bool Delegating) {
1589   return nullptr;
1590 }
1591 
1592 void MicrosoftCXXABI::EmitDestructorCall(CodeGenFunction &CGF,
1593                                          const CXXDestructorDecl *DD,
1594                                          CXXDtorType Type, bool ForVirtualBase,
1595                                          bool Delegating, Address This,
1596                                          QualType ThisTy) {
1597   // Use the base destructor variant in place of the complete destructor variant
1598   // if the class has no virtual bases. This effectively implements some of the
1599   // -mconstructor-aliases optimization, but as part of the MS C++ ABI.
1600   if (Type == Dtor_Complete && DD->getParent()->getNumVBases() == 0)
1601     Type = Dtor_Base;
1602 
1603   GlobalDecl GD(DD, Type);
1604   CGCallee Callee = CGCallee::forDirect(CGM.getAddrOfCXXStructor(GD), GD);
1605 
1606   if (DD->isVirtual()) {
1607     assert(Type != CXXDtorType::Dtor_Deleting &&
1608            "The deleting destructor should only be called via a virtual call");
1609     This = adjustThisArgumentForVirtualFunctionCall(CGF, GlobalDecl(DD, Type),
1610                                                     This, false);
1611   }
1612 
1613   llvm::BasicBlock *BaseDtorEndBB = nullptr;
1614   if (ForVirtualBase && isa<CXXConstructorDecl>(CGF.CurCodeDecl)) {
1615     BaseDtorEndBB = EmitDtorCompleteObjectHandler(CGF);
1616   }
1617 
1618   llvm::Value *Implicit =
1619       getCXXDestructorImplicitParam(CGF, DD, Type, ForVirtualBase,
1620                                     Delegating); // = nullptr
1621   CGF.EmitCXXDestructorCall(GD, Callee, This.getPointer(), ThisTy,
1622                             /*ImplicitParam=*/Implicit,
1623                             /*ImplicitParamTy=*/QualType(), nullptr);
1624   if (BaseDtorEndBB) {
1625     // Complete object handler should continue to be the remaining
1626     CGF.Builder.CreateBr(BaseDtorEndBB);
1627     CGF.EmitBlock(BaseDtorEndBB);
1628   }
1629 }
1630 
1631 void MicrosoftCXXABI::emitVTableTypeMetadata(const VPtrInfo &Info,
1632                                              const CXXRecordDecl *RD,
1633                                              llvm::GlobalVariable *VTable) {
1634   if (!CGM.getCodeGenOpts().LTOUnit)
1635     return;
1636 
1637   // TODO: Should VirtualFunctionElimination also be supported here?
1638   // See similar handling in CodeGenModule::EmitVTableTypeMetadata.
1639   if (CGM.getCodeGenOpts().WholeProgramVTables) {
1640     llvm::GlobalObject::VCallVisibility TypeVis =
1641         CGM.GetVCallVisibilityLevel(RD);
1642     if (TypeVis != llvm::GlobalObject::VCallVisibilityPublic)
1643       VTable->setVCallVisibilityMetadata(TypeVis);
1644   }
1645 
1646   // The location of the first virtual function pointer in the virtual table,
1647   // aka the "address point" on Itanium. This is at offset 0 if RTTI is
1648   // disabled, or sizeof(void*) if RTTI is enabled.
1649   CharUnits AddressPoint =
1650       getContext().getLangOpts().RTTIData
1651           ? getContext().toCharUnitsFromBits(
1652                 getContext().getTargetInfo().getPointerWidth(0))
1653           : CharUnits::Zero();
1654 
1655   if (Info.PathToIntroducingObject.empty()) {
1656     CGM.AddVTableTypeMetadata(VTable, AddressPoint, RD);
1657     return;
1658   }
1659 
1660   // Add a bitset entry for the least derived base belonging to this vftable.
1661   CGM.AddVTableTypeMetadata(VTable, AddressPoint,
1662                             Info.PathToIntroducingObject.back());
1663 
1664   // Add a bitset entry for each derived class that is laid out at the same
1665   // offset as the least derived base.
1666   for (unsigned I = Info.PathToIntroducingObject.size() - 1; I != 0; --I) {
1667     const CXXRecordDecl *DerivedRD = Info.PathToIntroducingObject[I - 1];
1668     const CXXRecordDecl *BaseRD = Info.PathToIntroducingObject[I];
1669 
1670     const ASTRecordLayout &Layout =
1671         getContext().getASTRecordLayout(DerivedRD);
1672     CharUnits Offset;
1673     auto VBI = Layout.getVBaseOffsetsMap().find(BaseRD);
1674     if (VBI == Layout.getVBaseOffsetsMap().end())
1675       Offset = Layout.getBaseClassOffset(BaseRD);
1676     else
1677       Offset = VBI->second.VBaseOffset;
1678     if (!Offset.isZero())
1679       return;
1680     CGM.AddVTableTypeMetadata(VTable, AddressPoint, DerivedRD);
1681   }
1682 
1683   // Finally do the same for the most derived class.
1684   if (Info.FullOffsetInMDC.isZero())
1685     CGM.AddVTableTypeMetadata(VTable, AddressPoint, RD);
1686 }
1687 
1688 void MicrosoftCXXABI::emitVTableDefinitions(CodeGenVTables &CGVT,
1689                                             const CXXRecordDecl *RD) {
1690   MicrosoftVTableContext &VFTContext = CGM.getMicrosoftVTableContext();
1691   const VPtrInfoVector &VFPtrs = VFTContext.getVFPtrOffsets(RD);
1692 
1693   for (const std::unique_ptr<VPtrInfo>& Info : VFPtrs) {
1694     llvm::GlobalVariable *VTable = getAddrOfVTable(RD, Info->FullOffsetInMDC);
1695     if (VTable->hasInitializer())
1696       continue;
1697 
1698     const VTableLayout &VTLayout =
1699       VFTContext.getVFTableLayout(RD, Info->FullOffsetInMDC);
1700 
1701     llvm::Constant *RTTI = nullptr;
1702     if (any_of(VTLayout.vtable_components(),
1703                [](const VTableComponent &VTC) { return VTC.isRTTIKind(); }))
1704       RTTI = getMSCompleteObjectLocator(RD, *Info);
1705 
1706     ConstantInitBuilder builder(CGM);
1707     auto components = builder.beginStruct();
1708     CGVT.createVTableInitializer(components, VTLayout, RTTI,
1709                                  VTable->hasLocalLinkage());
1710     components.finishAndSetAsInitializer(VTable);
1711 
1712     emitVTableTypeMetadata(*Info, RD, VTable);
1713   }
1714 }
1715 
1716 bool MicrosoftCXXABI::isVirtualOffsetNeededForVTableField(
1717     CodeGenFunction &CGF, CodeGenFunction::VPtr Vptr) {
1718   return Vptr.NearestVBase != nullptr;
1719 }
1720 
1721 llvm::Value *MicrosoftCXXABI::getVTableAddressPointInStructor(
1722     CodeGenFunction &CGF, const CXXRecordDecl *VTableClass, BaseSubobject Base,
1723     const CXXRecordDecl *NearestVBase) {
1724   llvm::Constant *VTableAddressPoint = getVTableAddressPoint(Base, VTableClass);
1725   if (!VTableAddressPoint) {
1726     assert(Base.getBase()->getNumVBases() &&
1727            !getContext().getASTRecordLayout(Base.getBase()).hasOwnVFPtr());
1728   }
1729   return VTableAddressPoint;
1730 }
1731 
1732 static void mangleVFTableName(MicrosoftMangleContext &MangleContext,
1733                               const CXXRecordDecl *RD, const VPtrInfo &VFPtr,
1734                               SmallString<256> &Name) {
1735   llvm::raw_svector_ostream Out(Name);
1736   MangleContext.mangleCXXVFTable(RD, VFPtr.MangledPath, Out);
1737 }
1738 
1739 llvm::Constant *
1740 MicrosoftCXXABI::getVTableAddressPoint(BaseSubobject Base,
1741                                        const CXXRecordDecl *VTableClass) {
1742   (void)getAddrOfVTable(VTableClass, Base.getBaseOffset());
1743   VFTableIdTy ID(VTableClass, Base.getBaseOffset());
1744   return VFTablesMap[ID];
1745 }
1746 
1747 llvm::Constant *MicrosoftCXXABI::getVTableAddressPointForConstExpr(
1748     BaseSubobject Base, const CXXRecordDecl *VTableClass) {
1749   llvm::Constant *VFTable = getVTableAddressPoint(Base, VTableClass);
1750   assert(VFTable && "Couldn't find a vftable for the given base?");
1751   return VFTable;
1752 }
1753 
1754 llvm::GlobalVariable *MicrosoftCXXABI::getAddrOfVTable(const CXXRecordDecl *RD,
1755                                                        CharUnits VPtrOffset) {
1756   // getAddrOfVTable may return 0 if asked to get an address of a vtable which
1757   // shouldn't be used in the given record type. We want to cache this result in
1758   // VFTablesMap, thus a simple zero check is not sufficient.
1759 
1760   VFTableIdTy ID(RD, VPtrOffset);
1761   VTablesMapTy::iterator I;
1762   bool Inserted;
1763   std::tie(I, Inserted) = VTablesMap.insert(std::make_pair(ID, nullptr));
1764   if (!Inserted)
1765     return I->second;
1766 
1767   llvm::GlobalVariable *&VTable = I->second;
1768 
1769   MicrosoftVTableContext &VTContext = CGM.getMicrosoftVTableContext();
1770   const VPtrInfoVector &VFPtrs = VTContext.getVFPtrOffsets(RD);
1771 
1772   if (DeferredVFTables.insert(RD).second) {
1773     // We haven't processed this record type before.
1774     // Queue up this vtable for possible deferred emission.
1775     CGM.addDeferredVTable(RD);
1776 
1777 #ifndef NDEBUG
1778     // Create all the vftables at once in order to make sure each vftable has
1779     // a unique mangled name.
1780     llvm::StringSet<> ObservedMangledNames;
1781     for (size_t J = 0, F = VFPtrs.size(); J != F; ++J) {
1782       SmallString<256> Name;
1783       mangleVFTableName(getMangleContext(), RD, *VFPtrs[J], Name);
1784       if (!ObservedMangledNames.insert(Name.str()).second)
1785         llvm_unreachable("Already saw this mangling before?");
1786     }
1787 #endif
1788   }
1789 
1790   const std::unique_ptr<VPtrInfo> *VFPtrI = std::find_if(
1791       VFPtrs.begin(), VFPtrs.end(), [&](const std::unique_ptr<VPtrInfo>& VPI) {
1792         return VPI->FullOffsetInMDC == VPtrOffset;
1793       });
1794   if (VFPtrI == VFPtrs.end()) {
1795     VFTablesMap[ID] = nullptr;
1796     return nullptr;
1797   }
1798   const std::unique_ptr<VPtrInfo> &VFPtr = *VFPtrI;
1799 
1800   SmallString<256> VFTableName;
1801   mangleVFTableName(getMangleContext(), RD, *VFPtr, VFTableName);
1802 
1803   // Classes marked __declspec(dllimport) need vftables generated on the
1804   // import-side in order to support features like constexpr.  No other
1805   // translation unit relies on the emission of the local vftable, translation
1806   // units are expected to generate them as needed.
1807   //
1808   // Because of this unique behavior, we maintain this logic here instead of
1809   // getVTableLinkage.
1810   llvm::GlobalValue::LinkageTypes VFTableLinkage =
1811       RD->hasAttr<DLLImportAttr>() ? llvm::GlobalValue::LinkOnceODRLinkage
1812                                    : CGM.getVTableLinkage(RD);
1813   bool VFTableComesFromAnotherTU =
1814       llvm::GlobalValue::isAvailableExternallyLinkage(VFTableLinkage) ||
1815       llvm::GlobalValue::isExternalLinkage(VFTableLinkage);
1816   bool VTableAliasIsRequred =
1817       !VFTableComesFromAnotherTU && getContext().getLangOpts().RTTIData;
1818 
1819   if (llvm::GlobalValue *VFTable =
1820           CGM.getModule().getNamedGlobal(VFTableName)) {
1821     VFTablesMap[ID] = VFTable;
1822     VTable = VTableAliasIsRequred
1823                  ? cast<llvm::GlobalVariable>(
1824                        cast<llvm::GlobalAlias>(VFTable)->getBaseObject())
1825                  : cast<llvm::GlobalVariable>(VFTable);
1826     return VTable;
1827   }
1828 
1829   const VTableLayout &VTLayout =
1830       VTContext.getVFTableLayout(RD, VFPtr->FullOffsetInMDC);
1831   llvm::GlobalValue::LinkageTypes VTableLinkage =
1832       VTableAliasIsRequred ? llvm::GlobalValue::PrivateLinkage : VFTableLinkage;
1833 
1834   StringRef VTableName = VTableAliasIsRequred ? StringRef() : VFTableName.str();
1835 
1836   llvm::Type *VTableType = CGM.getVTables().getVTableType(VTLayout);
1837 
1838   // Create a backing variable for the contents of VTable.  The VTable may
1839   // or may not include space for a pointer to RTTI data.
1840   llvm::GlobalValue *VFTable;
1841   VTable = new llvm::GlobalVariable(CGM.getModule(), VTableType,
1842                                     /*isConstant=*/true, VTableLinkage,
1843                                     /*Initializer=*/nullptr, VTableName);
1844   VTable->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
1845 
1846   llvm::Comdat *C = nullptr;
1847   if (!VFTableComesFromAnotherTU &&
1848       (llvm::GlobalValue::isWeakForLinker(VFTableLinkage) ||
1849        (llvm::GlobalValue::isLocalLinkage(VFTableLinkage) &&
1850         VTableAliasIsRequred)))
1851     C = CGM.getModule().getOrInsertComdat(VFTableName.str());
1852 
1853   // Only insert a pointer into the VFTable for RTTI data if we are not
1854   // importing it.  We never reference the RTTI data directly so there is no
1855   // need to make room for it.
1856   if (VTableAliasIsRequred) {
1857     llvm::Value *GEPIndices[] = {llvm::ConstantInt::get(CGM.Int32Ty, 0),
1858                                  llvm::ConstantInt::get(CGM.Int32Ty, 0),
1859                                  llvm::ConstantInt::get(CGM.Int32Ty, 1)};
1860     // Create a GEP which points just after the first entry in the VFTable,
1861     // this should be the location of the first virtual method.
1862     llvm::Constant *VTableGEP = llvm::ConstantExpr::getInBoundsGetElementPtr(
1863         VTable->getValueType(), VTable, GEPIndices);
1864     if (llvm::GlobalValue::isWeakForLinker(VFTableLinkage)) {
1865       VFTableLinkage = llvm::GlobalValue::ExternalLinkage;
1866       if (C)
1867         C->setSelectionKind(llvm::Comdat::Largest);
1868     }
1869     VFTable = llvm::GlobalAlias::create(CGM.Int8PtrTy,
1870                                         /*AddressSpace=*/0, VFTableLinkage,
1871                                         VFTableName.str(), VTableGEP,
1872                                         &CGM.getModule());
1873     VFTable->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
1874   } else {
1875     // We don't need a GlobalAlias to be a symbol for the VTable if we won't
1876     // be referencing any RTTI data.
1877     // The GlobalVariable will end up being an appropriate definition of the
1878     // VFTable.
1879     VFTable = VTable;
1880   }
1881   if (C)
1882     VTable->setComdat(C);
1883 
1884   if (RD->hasAttr<DLLExportAttr>())
1885     VFTable->setDLLStorageClass(llvm::GlobalValue::DLLExportStorageClass);
1886 
1887   VFTablesMap[ID] = VFTable;
1888   return VTable;
1889 }
1890 
1891 CGCallee MicrosoftCXXABI::getVirtualFunctionPointer(CodeGenFunction &CGF,
1892                                                     GlobalDecl GD,
1893                                                     Address This,
1894                                                     llvm::Type *Ty,
1895                                                     SourceLocation Loc) {
1896   CGBuilderTy &Builder = CGF.Builder;
1897 
1898   Ty = Ty->getPointerTo()->getPointerTo();
1899   Address VPtr =
1900       adjustThisArgumentForVirtualFunctionCall(CGF, GD, This, true);
1901 
1902   auto *MethodDecl = cast<CXXMethodDecl>(GD.getDecl());
1903   llvm::Value *VTable = CGF.GetVTablePtr(VPtr, Ty, MethodDecl->getParent());
1904 
1905   MicrosoftVTableContext &VFTContext = CGM.getMicrosoftVTableContext();
1906   MethodVFTableLocation ML = VFTContext.getMethodVFTableLocation(GD);
1907 
1908   // Compute the identity of the most derived class whose virtual table is
1909   // located at the MethodVFTableLocation ML.
1910   auto getObjectWithVPtr = [&] {
1911     return llvm::find_if(VFTContext.getVFPtrOffsets(
1912                              ML.VBase ? ML.VBase : MethodDecl->getParent()),
1913                          [&](const std::unique_ptr<VPtrInfo> &Info) {
1914                            return Info->FullOffsetInMDC == ML.VFPtrOffset;
1915                          })
1916         ->get()
1917         ->ObjectWithVPtr;
1918   };
1919 
1920   llvm::Value *VFunc;
1921   if (CGF.ShouldEmitVTableTypeCheckedLoad(MethodDecl->getParent())) {
1922     VFunc = CGF.EmitVTableTypeCheckedLoad(
1923         getObjectWithVPtr(), VTable,
1924         ML.Index * CGM.getContext().getTargetInfo().getPointerWidth(0) / 8);
1925   } else {
1926     if (CGM.getCodeGenOpts().PrepareForLTO)
1927       CGF.EmitTypeMetadataCodeForVCall(getObjectWithVPtr(), VTable, Loc);
1928 
1929     llvm::Value *VFuncPtr =
1930         Builder.CreateConstInBoundsGEP1_64(VTable, ML.Index, "vfn");
1931     VFunc = Builder.CreateAlignedLoad(VFuncPtr, CGF.getPointerAlign());
1932   }
1933 
1934   CGCallee Callee(GD, VFunc);
1935   return Callee;
1936 }
1937 
1938 llvm::Value *MicrosoftCXXABI::EmitVirtualDestructorCall(
1939     CodeGenFunction &CGF, const CXXDestructorDecl *Dtor, CXXDtorType DtorType,
1940     Address This, DeleteOrMemberCallExpr E) {
1941   auto *CE = E.dyn_cast<const CXXMemberCallExpr *>();
1942   auto *D = E.dyn_cast<const CXXDeleteExpr *>();
1943   assert((CE != nullptr) ^ (D != nullptr));
1944   assert(CE == nullptr || CE->arg_begin() == CE->arg_end());
1945   assert(DtorType == Dtor_Deleting || DtorType == Dtor_Complete);
1946 
1947   // We have only one destructor in the vftable but can get both behaviors
1948   // by passing an implicit int parameter.
1949   GlobalDecl GD(Dtor, Dtor_Deleting);
1950   const CGFunctionInfo *FInfo =
1951       &CGM.getTypes().arrangeCXXStructorDeclaration(GD);
1952   llvm::FunctionType *Ty = CGF.CGM.getTypes().GetFunctionType(*FInfo);
1953   CGCallee Callee = CGCallee::forVirtual(CE, GD, This, Ty);
1954 
1955   ASTContext &Context = getContext();
1956   llvm::Value *ImplicitParam = llvm::ConstantInt::get(
1957       llvm::IntegerType::getInt32Ty(CGF.getLLVMContext()),
1958       DtorType == Dtor_Deleting);
1959 
1960   QualType ThisTy;
1961   if (CE) {
1962     ThisTy = CE->getObjectType();
1963   } else {
1964     ThisTy = D->getDestroyedType();
1965   }
1966 
1967   This = adjustThisArgumentForVirtualFunctionCall(CGF, GD, This, true);
1968   RValue RV = CGF.EmitCXXDestructorCall(GD, Callee, This.getPointer(), ThisTy,
1969                                         ImplicitParam, Context.IntTy, CE);
1970   return RV.getScalarVal();
1971 }
1972 
1973 const VBTableGlobals &
1974 MicrosoftCXXABI::enumerateVBTables(const CXXRecordDecl *RD) {
1975   // At this layer, we can key the cache off of a single class, which is much
1976   // easier than caching each vbtable individually.
1977   llvm::DenseMap<const CXXRecordDecl*, VBTableGlobals>::iterator Entry;
1978   bool Added;
1979   std::tie(Entry, Added) =
1980       VBTablesMap.insert(std::make_pair(RD, VBTableGlobals()));
1981   VBTableGlobals &VBGlobals = Entry->second;
1982   if (!Added)
1983     return VBGlobals;
1984 
1985   MicrosoftVTableContext &Context = CGM.getMicrosoftVTableContext();
1986   VBGlobals.VBTables = &Context.enumerateVBTables(RD);
1987 
1988   // Cache the globals for all vbtables so we don't have to recompute the
1989   // mangled names.
1990   llvm::GlobalVariable::LinkageTypes Linkage = CGM.getVTableLinkage(RD);
1991   for (VPtrInfoVector::const_iterator I = VBGlobals.VBTables->begin(),
1992                                       E = VBGlobals.VBTables->end();
1993        I != E; ++I) {
1994     VBGlobals.Globals.push_back(getAddrOfVBTable(**I, RD, Linkage));
1995   }
1996 
1997   return VBGlobals;
1998 }
1999 
2000 llvm::Function *
2001 MicrosoftCXXABI::EmitVirtualMemPtrThunk(const CXXMethodDecl *MD,
2002                                         const MethodVFTableLocation &ML) {
2003   assert(!isa<CXXConstructorDecl>(MD) && !isa<CXXDestructorDecl>(MD) &&
2004          "can't form pointers to ctors or virtual dtors");
2005 
2006   // Calculate the mangled name.
2007   SmallString<256> ThunkName;
2008   llvm::raw_svector_ostream Out(ThunkName);
2009   getMangleContext().mangleVirtualMemPtrThunk(MD, ML, Out);
2010 
2011   // If the thunk has been generated previously, just return it.
2012   if (llvm::GlobalValue *GV = CGM.getModule().getNamedValue(ThunkName))
2013     return cast<llvm::Function>(GV);
2014 
2015   // Create the llvm::Function.
2016   const CGFunctionInfo &FnInfo =
2017       CGM.getTypes().arrangeUnprototypedMustTailThunk(MD);
2018   llvm::FunctionType *ThunkTy = CGM.getTypes().GetFunctionType(FnInfo);
2019   llvm::Function *ThunkFn =
2020       llvm::Function::Create(ThunkTy, llvm::Function::ExternalLinkage,
2021                              ThunkName.str(), &CGM.getModule());
2022   assert(ThunkFn->getName() == ThunkName && "name was uniqued!");
2023 
2024   ThunkFn->setLinkage(MD->isExternallyVisible()
2025                           ? llvm::GlobalValue::LinkOnceODRLinkage
2026                           : llvm::GlobalValue::InternalLinkage);
2027   if (MD->isExternallyVisible())
2028     ThunkFn->setComdat(CGM.getModule().getOrInsertComdat(ThunkFn->getName()));
2029 
2030   CGM.SetLLVMFunctionAttributes(MD, FnInfo, ThunkFn);
2031   CGM.SetLLVMFunctionAttributesForDefinition(MD, ThunkFn);
2032 
2033   // Add the "thunk" attribute so that LLVM knows that the return type is
2034   // meaningless. These thunks can be used to call functions with differing
2035   // return types, and the caller is required to cast the prototype
2036   // appropriately to extract the correct value.
2037   ThunkFn->addFnAttr("thunk");
2038 
2039   // These thunks can be compared, so they are not unnamed.
2040   ThunkFn->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::None);
2041 
2042   // Start codegen.
2043   CodeGenFunction CGF(CGM);
2044   CGF.CurGD = GlobalDecl(MD);
2045   CGF.CurFuncIsThunk = true;
2046 
2047   // Build FunctionArgs, but only include the implicit 'this' parameter
2048   // declaration.
2049   FunctionArgList FunctionArgs;
2050   buildThisParam(CGF, FunctionArgs);
2051 
2052   // Start defining the function.
2053   CGF.StartFunction(GlobalDecl(), FnInfo.getReturnType(), ThunkFn, FnInfo,
2054                     FunctionArgs, MD->getLocation(), SourceLocation());
2055   setCXXABIThisValue(CGF, loadIncomingCXXThis(CGF));
2056 
2057   // Load the vfptr and then callee from the vftable.  The callee should have
2058   // adjusted 'this' so that the vfptr is at offset zero.
2059   llvm::Value *VTable = CGF.GetVTablePtr(
2060       getThisAddress(CGF), ThunkTy->getPointerTo()->getPointerTo(), MD->getParent());
2061 
2062   llvm::Value *VFuncPtr =
2063       CGF.Builder.CreateConstInBoundsGEP1_64(VTable, ML.Index, "vfn");
2064   llvm::Value *Callee =
2065     CGF.Builder.CreateAlignedLoad(VFuncPtr, CGF.getPointerAlign());
2066 
2067   CGF.EmitMustTailThunk(MD, getThisValue(CGF), {ThunkTy, Callee});
2068 
2069   return ThunkFn;
2070 }
2071 
2072 void MicrosoftCXXABI::emitVirtualInheritanceTables(const CXXRecordDecl *RD) {
2073   const VBTableGlobals &VBGlobals = enumerateVBTables(RD);
2074   for (unsigned I = 0, E = VBGlobals.VBTables->size(); I != E; ++I) {
2075     const std::unique_ptr<VPtrInfo>& VBT = (*VBGlobals.VBTables)[I];
2076     llvm::GlobalVariable *GV = VBGlobals.Globals[I];
2077     if (GV->isDeclaration())
2078       emitVBTableDefinition(*VBT, RD, GV);
2079   }
2080 }
2081 
2082 llvm::GlobalVariable *
2083 MicrosoftCXXABI::getAddrOfVBTable(const VPtrInfo &VBT, const CXXRecordDecl *RD,
2084                                   llvm::GlobalVariable::LinkageTypes Linkage) {
2085   SmallString<256> OutName;
2086   llvm::raw_svector_ostream Out(OutName);
2087   getMangleContext().mangleCXXVBTable(RD, VBT.MangledPath, Out);
2088   StringRef Name = OutName.str();
2089 
2090   llvm::ArrayType *VBTableType =
2091       llvm::ArrayType::get(CGM.IntTy, 1 + VBT.ObjectWithVPtr->getNumVBases());
2092 
2093   assert(!CGM.getModule().getNamedGlobal(Name) &&
2094          "vbtable with this name already exists: mangling bug?");
2095   CharUnits Alignment =
2096       CGM.getContext().getTypeAlignInChars(CGM.getContext().IntTy);
2097   llvm::GlobalVariable *GV = CGM.CreateOrReplaceCXXRuntimeVariable(
2098       Name, VBTableType, Linkage, Alignment.getQuantity());
2099   GV->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
2100 
2101   if (RD->hasAttr<DLLImportAttr>())
2102     GV->setDLLStorageClass(llvm::GlobalValue::DLLImportStorageClass);
2103   else if (RD->hasAttr<DLLExportAttr>())
2104     GV->setDLLStorageClass(llvm::GlobalValue::DLLExportStorageClass);
2105 
2106   if (!GV->hasExternalLinkage())
2107     emitVBTableDefinition(VBT, RD, GV);
2108 
2109   return GV;
2110 }
2111 
2112 void MicrosoftCXXABI::emitVBTableDefinition(const VPtrInfo &VBT,
2113                                             const CXXRecordDecl *RD,
2114                                             llvm::GlobalVariable *GV) const {
2115   const CXXRecordDecl *ObjectWithVPtr = VBT.ObjectWithVPtr;
2116 
2117   assert(RD->getNumVBases() && ObjectWithVPtr->getNumVBases() &&
2118          "should only emit vbtables for classes with vbtables");
2119 
2120   const ASTRecordLayout &BaseLayout =
2121       getContext().getASTRecordLayout(VBT.IntroducingObject);
2122   const ASTRecordLayout &DerivedLayout = getContext().getASTRecordLayout(RD);
2123 
2124   SmallVector<llvm::Constant *, 4> Offsets(1 + ObjectWithVPtr->getNumVBases(),
2125                                            nullptr);
2126 
2127   // The offset from ObjectWithVPtr's vbptr to itself always leads.
2128   CharUnits VBPtrOffset = BaseLayout.getVBPtrOffset();
2129   Offsets[0] = llvm::ConstantInt::get(CGM.IntTy, -VBPtrOffset.getQuantity());
2130 
2131   MicrosoftVTableContext &Context = CGM.getMicrosoftVTableContext();
2132   for (const auto &I : ObjectWithVPtr->vbases()) {
2133     const CXXRecordDecl *VBase = I.getType()->getAsCXXRecordDecl();
2134     CharUnits Offset = DerivedLayout.getVBaseClassOffset(VBase);
2135     assert(!Offset.isNegative());
2136 
2137     // Make it relative to the subobject vbptr.
2138     CharUnits CompleteVBPtrOffset = VBT.NonVirtualOffset + VBPtrOffset;
2139     if (VBT.getVBaseWithVPtr())
2140       CompleteVBPtrOffset +=
2141           DerivedLayout.getVBaseClassOffset(VBT.getVBaseWithVPtr());
2142     Offset -= CompleteVBPtrOffset;
2143 
2144     unsigned VBIndex = Context.getVBTableIndex(ObjectWithVPtr, VBase);
2145     assert(Offsets[VBIndex] == nullptr && "The same vbindex seen twice?");
2146     Offsets[VBIndex] = llvm::ConstantInt::get(CGM.IntTy, Offset.getQuantity());
2147   }
2148 
2149   assert(Offsets.size() ==
2150          cast<llvm::ArrayType>(cast<llvm::PointerType>(GV->getType())
2151                                ->getElementType())->getNumElements());
2152   llvm::ArrayType *VBTableType =
2153     llvm::ArrayType::get(CGM.IntTy, Offsets.size());
2154   llvm::Constant *Init = llvm::ConstantArray::get(VBTableType, Offsets);
2155   GV->setInitializer(Init);
2156 
2157   if (RD->hasAttr<DLLImportAttr>())
2158     GV->setLinkage(llvm::GlobalVariable::AvailableExternallyLinkage);
2159 }
2160 
2161 llvm::Value *MicrosoftCXXABI::performThisAdjustment(CodeGenFunction &CGF,
2162                                                     Address This,
2163                                                     const ThisAdjustment &TA) {
2164   if (TA.isEmpty())
2165     return This.getPointer();
2166 
2167   This = CGF.Builder.CreateElementBitCast(This, CGF.Int8Ty);
2168 
2169   llvm::Value *V;
2170   if (TA.Virtual.isEmpty()) {
2171     V = This.getPointer();
2172   } else {
2173     assert(TA.Virtual.Microsoft.VtordispOffset < 0);
2174     // Adjust the this argument based on the vtordisp value.
2175     Address VtorDispPtr =
2176         CGF.Builder.CreateConstInBoundsByteGEP(This,
2177                  CharUnits::fromQuantity(TA.Virtual.Microsoft.VtordispOffset));
2178     VtorDispPtr = CGF.Builder.CreateElementBitCast(VtorDispPtr, CGF.Int32Ty);
2179     llvm::Value *VtorDisp = CGF.Builder.CreateLoad(VtorDispPtr, "vtordisp");
2180     V = CGF.Builder.CreateGEP(This.getPointer(),
2181                               CGF.Builder.CreateNeg(VtorDisp));
2182 
2183     // Unfortunately, having applied the vtordisp means that we no
2184     // longer really have a known alignment for the vbptr step.
2185     // We'll assume the vbptr is pointer-aligned.
2186 
2187     if (TA.Virtual.Microsoft.VBPtrOffset) {
2188       // If the final overrider is defined in a virtual base other than the one
2189       // that holds the vfptr, we have to use a vtordispex thunk which looks up
2190       // the vbtable of the derived class.
2191       assert(TA.Virtual.Microsoft.VBPtrOffset > 0);
2192       assert(TA.Virtual.Microsoft.VBOffsetOffset >= 0);
2193       llvm::Value *VBPtr;
2194       llvm::Value *VBaseOffset =
2195           GetVBaseOffsetFromVBPtr(CGF, Address(V, CGF.getPointerAlign()),
2196                                   -TA.Virtual.Microsoft.VBPtrOffset,
2197                                   TA.Virtual.Microsoft.VBOffsetOffset, &VBPtr);
2198       V = CGF.Builder.CreateInBoundsGEP(VBPtr, VBaseOffset);
2199     }
2200   }
2201 
2202   if (TA.NonVirtual) {
2203     // Non-virtual adjustment might result in a pointer outside the allocated
2204     // object, e.g. if the final overrider class is laid out after the virtual
2205     // base that declares a method in the most derived class.
2206     V = CGF.Builder.CreateConstGEP1_32(V, TA.NonVirtual);
2207   }
2208 
2209   // Don't need to bitcast back, the call CodeGen will handle this.
2210   return V;
2211 }
2212 
2213 llvm::Value *
2214 MicrosoftCXXABI::performReturnAdjustment(CodeGenFunction &CGF, Address Ret,
2215                                          const ReturnAdjustment &RA) {
2216   if (RA.isEmpty())
2217     return Ret.getPointer();
2218 
2219   auto OrigTy = Ret.getType();
2220   Ret = CGF.Builder.CreateElementBitCast(Ret, CGF.Int8Ty);
2221 
2222   llvm::Value *V = Ret.getPointer();
2223   if (RA.Virtual.Microsoft.VBIndex) {
2224     assert(RA.Virtual.Microsoft.VBIndex > 0);
2225     int32_t IntSize = CGF.getIntSize().getQuantity();
2226     llvm::Value *VBPtr;
2227     llvm::Value *VBaseOffset =
2228         GetVBaseOffsetFromVBPtr(CGF, Ret, RA.Virtual.Microsoft.VBPtrOffset,
2229                                 IntSize * RA.Virtual.Microsoft.VBIndex, &VBPtr);
2230     V = CGF.Builder.CreateInBoundsGEP(VBPtr, VBaseOffset);
2231   }
2232 
2233   if (RA.NonVirtual)
2234     V = CGF.Builder.CreateConstInBoundsGEP1_32(CGF.Int8Ty, V, RA.NonVirtual);
2235 
2236   // Cast back to the original type.
2237   return CGF.Builder.CreateBitCast(V, OrigTy);
2238 }
2239 
2240 bool MicrosoftCXXABI::requiresArrayCookie(const CXXDeleteExpr *expr,
2241                                    QualType elementType) {
2242   // Microsoft seems to completely ignore the possibility of a
2243   // two-argument usual deallocation function.
2244   return elementType.isDestructedType();
2245 }
2246 
2247 bool MicrosoftCXXABI::requiresArrayCookie(const CXXNewExpr *expr) {
2248   // Microsoft seems to completely ignore the possibility of a
2249   // two-argument usual deallocation function.
2250   return expr->getAllocatedType().isDestructedType();
2251 }
2252 
2253 CharUnits MicrosoftCXXABI::getArrayCookieSizeImpl(QualType type) {
2254   // The array cookie is always a size_t; we then pad that out to the
2255   // alignment of the element type.
2256   ASTContext &Ctx = getContext();
2257   return std::max(Ctx.getTypeSizeInChars(Ctx.getSizeType()),
2258                   Ctx.getTypeAlignInChars(type));
2259 }
2260 
2261 llvm::Value *MicrosoftCXXABI::readArrayCookieImpl(CodeGenFunction &CGF,
2262                                                   Address allocPtr,
2263                                                   CharUnits cookieSize) {
2264   Address numElementsPtr =
2265     CGF.Builder.CreateElementBitCast(allocPtr, CGF.SizeTy);
2266   return CGF.Builder.CreateLoad(numElementsPtr);
2267 }
2268 
2269 Address MicrosoftCXXABI::InitializeArrayCookie(CodeGenFunction &CGF,
2270                                                Address newPtr,
2271                                                llvm::Value *numElements,
2272                                                const CXXNewExpr *expr,
2273                                                QualType elementType) {
2274   assert(requiresArrayCookie(expr));
2275 
2276   // The size of the cookie.
2277   CharUnits cookieSize = getArrayCookieSizeImpl(elementType);
2278 
2279   // Compute an offset to the cookie.
2280   Address cookiePtr = newPtr;
2281 
2282   // Write the number of elements into the appropriate slot.
2283   Address numElementsPtr
2284     = CGF.Builder.CreateElementBitCast(cookiePtr, CGF.SizeTy);
2285   CGF.Builder.CreateStore(numElements, numElementsPtr);
2286 
2287   // Finally, compute a pointer to the actual data buffer by skipping
2288   // over the cookie completely.
2289   return CGF.Builder.CreateConstInBoundsByteGEP(newPtr, cookieSize);
2290 }
2291 
2292 static void emitGlobalDtorWithTLRegDtor(CodeGenFunction &CGF, const VarDecl &VD,
2293                                         llvm::FunctionCallee Dtor,
2294                                         llvm::Constant *Addr) {
2295   // Create a function which calls the destructor.
2296   llvm::Constant *DtorStub = CGF.createAtExitStub(VD, Dtor, Addr);
2297 
2298   // extern "C" int __tlregdtor(void (*f)(void));
2299   llvm::FunctionType *TLRegDtorTy = llvm::FunctionType::get(
2300       CGF.IntTy, DtorStub->getType(), /*isVarArg=*/false);
2301 
2302   llvm::FunctionCallee TLRegDtor = CGF.CGM.CreateRuntimeFunction(
2303       TLRegDtorTy, "__tlregdtor", llvm::AttributeList(), /*Local=*/true);
2304   if (llvm::Function *TLRegDtorFn =
2305           dyn_cast<llvm::Function>(TLRegDtor.getCallee()))
2306     TLRegDtorFn->setDoesNotThrow();
2307 
2308   CGF.EmitNounwindRuntimeCall(TLRegDtor, DtorStub);
2309 }
2310 
2311 void MicrosoftCXXABI::registerGlobalDtor(CodeGenFunction &CGF, const VarDecl &D,
2312                                          llvm::FunctionCallee Dtor,
2313                                          llvm::Constant *Addr) {
2314   if (D.isNoDestroy(CGM.getContext()))
2315     return;
2316 
2317   if (D.getTLSKind())
2318     return emitGlobalDtorWithTLRegDtor(CGF, D, Dtor, Addr);
2319 
2320   // The default behavior is to use atexit.
2321   CGF.registerGlobalDtorWithAtExit(D, Dtor, Addr);
2322 }
2323 
2324 void MicrosoftCXXABI::EmitThreadLocalInitFuncs(
2325     CodeGenModule &CGM, ArrayRef<const VarDecl *> CXXThreadLocals,
2326     ArrayRef<llvm::Function *> CXXThreadLocalInits,
2327     ArrayRef<const VarDecl *> CXXThreadLocalInitVars) {
2328   if (CXXThreadLocalInits.empty())
2329     return;
2330 
2331   CGM.AppendLinkerOptions(CGM.getTarget().getTriple().getArch() ==
2332                                   llvm::Triple::x86
2333                               ? "/include:___dyn_tls_init@12"
2334                               : "/include:__dyn_tls_init");
2335 
2336   // This will create a GV in the .CRT$XDU section.  It will point to our
2337   // initialization function.  The CRT will call all of these function
2338   // pointers at start-up time and, eventually, at thread-creation time.
2339   auto AddToXDU = [&CGM](llvm::Function *InitFunc) {
2340     llvm::GlobalVariable *InitFuncPtr = new llvm::GlobalVariable(
2341         CGM.getModule(), InitFunc->getType(), /*isConstant=*/true,
2342         llvm::GlobalVariable::InternalLinkage, InitFunc,
2343         Twine(InitFunc->getName(), "$initializer$"));
2344     InitFuncPtr->setSection(".CRT$XDU");
2345     // This variable has discardable linkage, we have to add it to @llvm.used to
2346     // ensure it won't get discarded.
2347     CGM.addUsedGlobal(InitFuncPtr);
2348     return InitFuncPtr;
2349   };
2350 
2351   std::vector<llvm::Function *> NonComdatInits;
2352   for (size_t I = 0, E = CXXThreadLocalInitVars.size(); I != E; ++I) {
2353     llvm::GlobalVariable *GV = cast<llvm::GlobalVariable>(
2354         CGM.GetGlobalValue(CGM.getMangledName(CXXThreadLocalInitVars[I])));
2355     llvm::Function *F = CXXThreadLocalInits[I];
2356 
2357     // If the GV is already in a comdat group, then we have to join it.
2358     if (llvm::Comdat *C = GV->getComdat())
2359       AddToXDU(F)->setComdat(C);
2360     else
2361       NonComdatInits.push_back(F);
2362   }
2363 
2364   if (!NonComdatInits.empty()) {
2365     llvm::FunctionType *FTy =
2366         llvm::FunctionType::get(CGM.VoidTy, /*isVarArg=*/false);
2367     llvm::Function *InitFunc = CGM.CreateGlobalInitOrCleanUpFunction(
2368         FTy, "__tls_init", CGM.getTypes().arrangeNullaryFunction(),
2369         SourceLocation(), /*TLS=*/true);
2370     CodeGenFunction(CGM).GenerateCXXGlobalInitFunc(InitFunc, NonComdatInits);
2371 
2372     AddToXDU(InitFunc);
2373   }
2374 }
2375 
2376 LValue MicrosoftCXXABI::EmitThreadLocalVarDeclLValue(CodeGenFunction &CGF,
2377                                                      const VarDecl *VD,
2378                                                      QualType LValType) {
2379   CGF.CGM.ErrorUnsupported(VD, "thread wrappers");
2380   return LValue();
2381 }
2382 
2383 static ConstantAddress getInitThreadEpochPtr(CodeGenModule &CGM) {
2384   StringRef VarName("_Init_thread_epoch");
2385   CharUnits Align = CGM.getIntAlign();
2386   if (auto *GV = CGM.getModule().getNamedGlobal(VarName))
2387     return ConstantAddress(GV, Align);
2388   auto *GV = new llvm::GlobalVariable(
2389       CGM.getModule(), CGM.IntTy,
2390       /*isConstant=*/false, llvm::GlobalVariable::ExternalLinkage,
2391       /*Initializer=*/nullptr, VarName,
2392       /*InsertBefore=*/nullptr, llvm::GlobalVariable::GeneralDynamicTLSModel);
2393   GV->setAlignment(Align.getAsAlign());
2394   return ConstantAddress(GV, Align);
2395 }
2396 
2397 static llvm::FunctionCallee getInitThreadHeaderFn(CodeGenModule &CGM) {
2398   llvm::FunctionType *FTy =
2399       llvm::FunctionType::get(llvm::Type::getVoidTy(CGM.getLLVMContext()),
2400                               CGM.IntTy->getPointerTo(), /*isVarArg=*/false);
2401   return CGM.CreateRuntimeFunction(
2402       FTy, "_Init_thread_header",
2403       llvm::AttributeList::get(CGM.getLLVMContext(),
2404                                llvm::AttributeList::FunctionIndex,
2405                                llvm::Attribute::NoUnwind),
2406       /*Local=*/true);
2407 }
2408 
2409 static llvm::FunctionCallee getInitThreadFooterFn(CodeGenModule &CGM) {
2410   llvm::FunctionType *FTy =
2411       llvm::FunctionType::get(llvm::Type::getVoidTy(CGM.getLLVMContext()),
2412                               CGM.IntTy->getPointerTo(), /*isVarArg=*/false);
2413   return CGM.CreateRuntimeFunction(
2414       FTy, "_Init_thread_footer",
2415       llvm::AttributeList::get(CGM.getLLVMContext(),
2416                                llvm::AttributeList::FunctionIndex,
2417                                llvm::Attribute::NoUnwind),
2418       /*Local=*/true);
2419 }
2420 
2421 static llvm::FunctionCallee getInitThreadAbortFn(CodeGenModule &CGM) {
2422   llvm::FunctionType *FTy =
2423       llvm::FunctionType::get(llvm::Type::getVoidTy(CGM.getLLVMContext()),
2424                               CGM.IntTy->getPointerTo(), /*isVarArg=*/false);
2425   return CGM.CreateRuntimeFunction(
2426       FTy, "_Init_thread_abort",
2427       llvm::AttributeList::get(CGM.getLLVMContext(),
2428                                llvm::AttributeList::FunctionIndex,
2429                                llvm::Attribute::NoUnwind),
2430       /*Local=*/true);
2431 }
2432 
2433 namespace {
2434 struct ResetGuardBit final : EHScopeStack::Cleanup {
2435   Address Guard;
2436   unsigned GuardNum;
2437   ResetGuardBit(Address Guard, unsigned GuardNum)
2438       : Guard(Guard), GuardNum(GuardNum) {}
2439 
2440   void Emit(CodeGenFunction &CGF, Flags flags) override {
2441     // Reset the bit in the mask so that the static variable may be
2442     // reinitialized.
2443     CGBuilderTy &Builder = CGF.Builder;
2444     llvm::LoadInst *LI = Builder.CreateLoad(Guard);
2445     llvm::ConstantInt *Mask =
2446         llvm::ConstantInt::get(CGF.IntTy, ~(1ULL << GuardNum));
2447     Builder.CreateStore(Builder.CreateAnd(LI, Mask), Guard);
2448   }
2449 };
2450 
2451 struct CallInitThreadAbort final : EHScopeStack::Cleanup {
2452   llvm::Value *Guard;
2453   CallInitThreadAbort(Address Guard) : Guard(Guard.getPointer()) {}
2454 
2455   void Emit(CodeGenFunction &CGF, Flags flags) override {
2456     // Calling _Init_thread_abort will reset the guard's state.
2457     CGF.EmitNounwindRuntimeCall(getInitThreadAbortFn(CGF.CGM), Guard);
2458   }
2459 };
2460 }
2461 
2462 void MicrosoftCXXABI::EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D,
2463                                       llvm::GlobalVariable *GV,
2464                                       bool PerformInit) {
2465   // MSVC only uses guards for static locals.
2466   if (!D.isStaticLocal()) {
2467     assert(GV->hasWeakLinkage() || GV->hasLinkOnceLinkage());
2468     // GlobalOpt is allowed to discard the initializer, so use linkonce_odr.
2469     llvm::Function *F = CGF.CurFn;
2470     F->setLinkage(llvm::GlobalValue::LinkOnceODRLinkage);
2471     F->setComdat(CGM.getModule().getOrInsertComdat(F->getName()));
2472     CGF.EmitCXXGlobalVarDeclInit(D, GV, PerformInit);
2473     return;
2474   }
2475 
2476   bool ThreadlocalStatic = D.getTLSKind();
2477   bool ThreadsafeStatic = getContext().getLangOpts().ThreadsafeStatics;
2478 
2479   // Thread-safe static variables which aren't thread-specific have a
2480   // per-variable guard.
2481   bool HasPerVariableGuard = ThreadsafeStatic && !ThreadlocalStatic;
2482 
2483   CGBuilderTy &Builder = CGF.Builder;
2484   llvm::IntegerType *GuardTy = CGF.Int32Ty;
2485   llvm::ConstantInt *Zero = llvm::ConstantInt::get(GuardTy, 0);
2486   CharUnits GuardAlign = CharUnits::fromQuantity(4);
2487 
2488   // Get the guard variable for this function if we have one already.
2489   GuardInfo *GI = nullptr;
2490   if (ThreadlocalStatic)
2491     GI = &ThreadLocalGuardVariableMap[D.getDeclContext()];
2492   else if (!ThreadsafeStatic)
2493     GI = &GuardVariableMap[D.getDeclContext()];
2494 
2495   llvm::GlobalVariable *GuardVar = GI ? GI->Guard : nullptr;
2496   unsigned GuardNum;
2497   if (D.isExternallyVisible()) {
2498     // Externally visible variables have to be numbered in Sema to properly
2499     // handle unreachable VarDecls.
2500     GuardNum = getContext().getStaticLocalNumber(&D);
2501     assert(GuardNum > 0);
2502     GuardNum--;
2503   } else if (HasPerVariableGuard) {
2504     GuardNum = ThreadSafeGuardNumMap[D.getDeclContext()]++;
2505   } else {
2506     // Non-externally visible variables are numbered here in CodeGen.
2507     GuardNum = GI->BitIndex++;
2508   }
2509 
2510   if (!HasPerVariableGuard && GuardNum >= 32) {
2511     if (D.isExternallyVisible())
2512       ErrorUnsupportedABI(CGF, "more than 32 guarded initializations");
2513     GuardNum %= 32;
2514     GuardVar = nullptr;
2515   }
2516 
2517   if (!GuardVar) {
2518     // Mangle the name for the guard.
2519     SmallString<256> GuardName;
2520     {
2521       llvm::raw_svector_ostream Out(GuardName);
2522       if (HasPerVariableGuard)
2523         getMangleContext().mangleThreadSafeStaticGuardVariable(&D, GuardNum,
2524                                                                Out);
2525       else
2526         getMangleContext().mangleStaticGuardVariable(&D, Out);
2527     }
2528 
2529     // Create the guard variable with a zero-initializer. Just absorb linkage,
2530     // visibility and dll storage class from the guarded variable.
2531     GuardVar =
2532         new llvm::GlobalVariable(CGM.getModule(), GuardTy, /*isConstant=*/false,
2533                                  GV->getLinkage(), Zero, GuardName.str());
2534     GuardVar->setVisibility(GV->getVisibility());
2535     GuardVar->setDLLStorageClass(GV->getDLLStorageClass());
2536     GuardVar->setAlignment(GuardAlign.getAsAlign());
2537     if (GuardVar->isWeakForLinker())
2538       GuardVar->setComdat(
2539           CGM.getModule().getOrInsertComdat(GuardVar->getName()));
2540     if (D.getTLSKind())
2541       CGM.setTLSMode(GuardVar, D);
2542     if (GI && !HasPerVariableGuard)
2543       GI->Guard = GuardVar;
2544   }
2545 
2546   ConstantAddress GuardAddr(GuardVar, GuardAlign);
2547 
2548   assert(GuardVar->getLinkage() == GV->getLinkage() &&
2549          "static local from the same function had different linkage");
2550 
2551   if (!HasPerVariableGuard) {
2552     // Pseudo code for the test:
2553     // if (!(GuardVar & MyGuardBit)) {
2554     //   GuardVar |= MyGuardBit;
2555     //   ... initialize the object ...;
2556     // }
2557 
2558     // Test our bit from the guard variable.
2559     llvm::ConstantInt *Bit = llvm::ConstantInt::get(GuardTy, 1ULL << GuardNum);
2560     llvm::LoadInst *LI = Builder.CreateLoad(GuardAddr);
2561     llvm::Value *NeedsInit =
2562         Builder.CreateICmpEQ(Builder.CreateAnd(LI, Bit), Zero);
2563     llvm::BasicBlock *InitBlock = CGF.createBasicBlock("init");
2564     llvm::BasicBlock *EndBlock = CGF.createBasicBlock("init.end");
2565     CGF.EmitCXXGuardedInitBranch(NeedsInit, InitBlock, EndBlock,
2566                                  CodeGenFunction::GuardKind::VariableGuard, &D);
2567 
2568     // Set our bit in the guard variable and emit the initializer and add a global
2569     // destructor if appropriate.
2570     CGF.EmitBlock(InitBlock);
2571     Builder.CreateStore(Builder.CreateOr(LI, Bit), GuardAddr);
2572     CGF.EHStack.pushCleanup<ResetGuardBit>(EHCleanup, GuardAddr, GuardNum);
2573     CGF.EmitCXXGlobalVarDeclInit(D, GV, PerformInit);
2574     CGF.PopCleanupBlock();
2575     Builder.CreateBr(EndBlock);
2576 
2577     // Continue.
2578     CGF.EmitBlock(EndBlock);
2579   } else {
2580     // Pseudo code for the test:
2581     // if (TSS > _Init_thread_epoch) {
2582     //   _Init_thread_header(&TSS);
2583     //   if (TSS == -1) {
2584     //     ... initialize the object ...;
2585     //     _Init_thread_footer(&TSS);
2586     //   }
2587     // }
2588     //
2589     // The algorithm is almost identical to what can be found in the appendix
2590     // found in N2325.
2591 
2592     // This BasicBLock determines whether or not we have any work to do.
2593     llvm::LoadInst *FirstGuardLoad = Builder.CreateLoad(GuardAddr);
2594     FirstGuardLoad->setOrdering(llvm::AtomicOrdering::Unordered);
2595     llvm::LoadInst *InitThreadEpoch =
2596         Builder.CreateLoad(getInitThreadEpochPtr(CGM));
2597     llvm::Value *IsUninitialized =
2598         Builder.CreateICmpSGT(FirstGuardLoad, InitThreadEpoch);
2599     llvm::BasicBlock *AttemptInitBlock = CGF.createBasicBlock("init.attempt");
2600     llvm::BasicBlock *EndBlock = CGF.createBasicBlock("init.end");
2601     CGF.EmitCXXGuardedInitBranch(IsUninitialized, AttemptInitBlock, EndBlock,
2602                                  CodeGenFunction::GuardKind::VariableGuard, &D);
2603 
2604     // This BasicBlock attempts to determine whether or not this thread is
2605     // responsible for doing the initialization.
2606     CGF.EmitBlock(AttemptInitBlock);
2607     CGF.EmitNounwindRuntimeCall(getInitThreadHeaderFn(CGM),
2608                                 GuardAddr.getPointer());
2609     llvm::LoadInst *SecondGuardLoad = Builder.CreateLoad(GuardAddr);
2610     SecondGuardLoad->setOrdering(llvm::AtomicOrdering::Unordered);
2611     llvm::Value *ShouldDoInit =
2612         Builder.CreateICmpEQ(SecondGuardLoad, getAllOnesInt());
2613     llvm::BasicBlock *InitBlock = CGF.createBasicBlock("init");
2614     Builder.CreateCondBr(ShouldDoInit, InitBlock, EndBlock);
2615 
2616     // Ok, we ended up getting selected as the initializing thread.
2617     CGF.EmitBlock(InitBlock);
2618     CGF.EHStack.pushCleanup<CallInitThreadAbort>(EHCleanup, GuardAddr);
2619     CGF.EmitCXXGlobalVarDeclInit(D, GV, PerformInit);
2620     CGF.PopCleanupBlock();
2621     CGF.EmitNounwindRuntimeCall(getInitThreadFooterFn(CGM),
2622                                 GuardAddr.getPointer());
2623     Builder.CreateBr(EndBlock);
2624 
2625     CGF.EmitBlock(EndBlock);
2626   }
2627 }
2628 
2629 bool MicrosoftCXXABI::isZeroInitializable(const MemberPointerType *MPT) {
2630   // Null-ness for function memptrs only depends on the first field, which is
2631   // the function pointer.  The rest don't matter, so we can zero initialize.
2632   if (MPT->isMemberFunctionPointer())
2633     return true;
2634 
2635   // The virtual base adjustment field is always -1 for null, so if we have one
2636   // we can't zero initialize.  The field offset is sometimes also -1 if 0 is a
2637   // valid field offset.
2638   const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();
2639   MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
2640   return (!inheritanceModelHasVBTableOffsetField(Inheritance) &&
2641           RD->nullFieldOffsetIsZero());
2642 }
2643 
2644 llvm::Type *
2645 MicrosoftCXXABI::ConvertMemberPointerType(const MemberPointerType *MPT) {
2646   const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();
2647   MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
2648   llvm::SmallVector<llvm::Type *, 4> fields;
2649   if (MPT->isMemberFunctionPointer())
2650     fields.push_back(CGM.VoidPtrTy);  // FunctionPointerOrVirtualThunk
2651   else
2652     fields.push_back(CGM.IntTy);  // FieldOffset
2653 
2654   if (inheritanceModelHasNVOffsetField(MPT->isMemberFunctionPointer(),
2655                                        Inheritance))
2656     fields.push_back(CGM.IntTy);
2657   if (inheritanceModelHasVBPtrOffsetField(Inheritance))
2658     fields.push_back(CGM.IntTy);
2659   if (inheritanceModelHasVBTableOffsetField(Inheritance))
2660     fields.push_back(CGM.IntTy);  // VirtualBaseAdjustmentOffset
2661 
2662   if (fields.size() == 1)
2663     return fields[0];
2664   return llvm::StructType::get(CGM.getLLVMContext(), fields);
2665 }
2666 
2667 void MicrosoftCXXABI::
2668 GetNullMemberPointerFields(const MemberPointerType *MPT,
2669                            llvm::SmallVectorImpl<llvm::Constant *> &fields) {
2670   assert(fields.empty());
2671   const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();
2672   MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
2673   if (MPT->isMemberFunctionPointer()) {
2674     // FunctionPointerOrVirtualThunk
2675     fields.push_back(llvm::Constant::getNullValue(CGM.VoidPtrTy));
2676   } else {
2677     if (RD->nullFieldOffsetIsZero())
2678       fields.push_back(getZeroInt());  // FieldOffset
2679     else
2680       fields.push_back(getAllOnesInt());  // FieldOffset
2681   }
2682 
2683   if (inheritanceModelHasNVOffsetField(MPT->isMemberFunctionPointer(),
2684                                        Inheritance))
2685     fields.push_back(getZeroInt());
2686   if (inheritanceModelHasVBPtrOffsetField(Inheritance))
2687     fields.push_back(getZeroInt());
2688   if (inheritanceModelHasVBTableOffsetField(Inheritance))
2689     fields.push_back(getAllOnesInt());
2690 }
2691 
2692 llvm::Constant *
2693 MicrosoftCXXABI::EmitNullMemberPointer(const MemberPointerType *MPT) {
2694   llvm::SmallVector<llvm::Constant *, 4> fields;
2695   GetNullMemberPointerFields(MPT, fields);
2696   if (fields.size() == 1)
2697     return fields[0];
2698   llvm::Constant *Res = llvm::ConstantStruct::getAnon(fields);
2699   assert(Res->getType() == ConvertMemberPointerType(MPT));
2700   return Res;
2701 }
2702 
2703 llvm::Constant *
2704 MicrosoftCXXABI::EmitFullMemberPointer(llvm::Constant *FirstField,
2705                                        bool IsMemberFunction,
2706                                        const CXXRecordDecl *RD,
2707                                        CharUnits NonVirtualBaseAdjustment,
2708                                        unsigned VBTableIndex) {
2709   MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
2710 
2711   // Single inheritance class member pointer are represented as scalars instead
2712   // of aggregates.
2713   if (inheritanceModelHasOnlyOneField(IsMemberFunction, Inheritance))
2714     return FirstField;
2715 
2716   llvm::SmallVector<llvm::Constant *, 4> fields;
2717   fields.push_back(FirstField);
2718 
2719   if (inheritanceModelHasNVOffsetField(IsMemberFunction, Inheritance))
2720     fields.push_back(llvm::ConstantInt::get(
2721       CGM.IntTy, NonVirtualBaseAdjustment.getQuantity()));
2722 
2723   if (inheritanceModelHasVBPtrOffsetField(Inheritance)) {
2724     CharUnits Offs = CharUnits::Zero();
2725     if (VBTableIndex)
2726       Offs = getContext().getASTRecordLayout(RD).getVBPtrOffset();
2727     fields.push_back(llvm::ConstantInt::get(CGM.IntTy, Offs.getQuantity()));
2728   }
2729 
2730   // The rest of the fields are adjusted by conversions to a more derived class.
2731   if (inheritanceModelHasVBTableOffsetField(Inheritance))
2732     fields.push_back(llvm::ConstantInt::get(CGM.IntTy, VBTableIndex));
2733 
2734   return llvm::ConstantStruct::getAnon(fields);
2735 }
2736 
2737 llvm::Constant *
2738 MicrosoftCXXABI::EmitMemberDataPointer(const MemberPointerType *MPT,
2739                                        CharUnits offset) {
2740   return EmitMemberDataPointer(MPT->getMostRecentCXXRecordDecl(), offset);
2741 }
2742 
2743 llvm::Constant *MicrosoftCXXABI::EmitMemberDataPointer(const CXXRecordDecl *RD,
2744                                                        CharUnits offset) {
2745   if (RD->getMSInheritanceModel() ==
2746       MSInheritanceModel::Virtual)
2747     offset -= getContext().getOffsetOfBaseWithVBPtr(RD);
2748   llvm::Constant *FirstField =
2749     llvm::ConstantInt::get(CGM.IntTy, offset.getQuantity());
2750   return EmitFullMemberPointer(FirstField, /*IsMemberFunction=*/false, RD,
2751                                CharUnits::Zero(), /*VBTableIndex=*/0);
2752 }
2753 
2754 llvm::Constant *MicrosoftCXXABI::EmitMemberPointer(const APValue &MP,
2755                                                    QualType MPType) {
2756   const MemberPointerType *DstTy = MPType->castAs<MemberPointerType>();
2757   const ValueDecl *MPD = MP.getMemberPointerDecl();
2758   if (!MPD)
2759     return EmitNullMemberPointer(DstTy);
2760 
2761   ASTContext &Ctx = getContext();
2762   ArrayRef<const CXXRecordDecl *> MemberPointerPath = MP.getMemberPointerPath();
2763 
2764   llvm::Constant *C;
2765   if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(MPD)) {
2766     C = EmitMemberFunctionPointer(MD);
2767   } else {
2768     // For a pointer to data member, start off with the offset of the field in
2769     // the class in which it was declared, and convert from there if necessary.
2770     // For indirect field decls, get the outermost anonymous field and use the
2771     // parent class.
2772     CharUnits FieldOffset = Ctx.toCharUnitsFromBits(Ctx.getFieldOffset(MPD));
2773     const FieldDecl *FD = dyn_cast<FieldDecl>(MPD);
2774     if (!FD)
2775       FD = cast<FieldDecl>(*cast<IndirectFieldDecl>(MPD)->chain_begin());
2776     const CXXRecordDecl *RD = cast<CXXRecordDecl>(FD->getParent());
2777     RD = RD->getMostRecentNonInjectedDecl();
2778     C = EmitMemberDataPointer(RD, FieldOffset);
2779   }
2780 
2781   if (!MemberPointerPath.empty()) {
2782     const CXXRecordDecl *SrcRD = cast<CXXRecordDecl>(MPD->getDeclContext());
2783     const Type *SrcRecTy = Ctx.getTypeDeclType(SrcRD).getTypePtr();
2784     const MemberPointerType *SrcTy =
2785         Ctx.getMemberPointerType(DstTy->getPointeeType(), SrcRecTy)
2786             ->castAs<MemberPointerType>();
2787 
2788     bool DerivedMember = MP.isMemberPointerToDerivedMember();
2789     SmallVector<const CXXBaseSpecifier *, 4> DerivedToBasePath;
2790     const CXXRecordDecl *PrevRD = SrcRD;
2791     for (const CXXRecordDecl *PathElem : MemberPointerPath) {
2792       const CXXRecordDecl *Base = nullptr;
2793       const CXXRecordDecl *Derived = nullptr;
2794       if (DerivedMember) {
2795         Base = PathElem;
2796         Derived = PrevRD;
2797       } else {
2798         Base = PrevRD;
2799         Derived = PathElem;
2800       }
2801       for (const CXXBaseSpecifier &BS : Derived->bases())
2802         if (BS.getType()->getAsCXXRecordDecl()->getCanonicalDecl() ==
2803             Base->getCanonicalDecl())
2804           DerivedToBasePath.push_back(&BS);
2805       PrevRD = PathElem;
2806     }
2807     assert(DerivedToBasePath.size() == MemberPointerPath.size());
2808 
2809     CastKind CK = DerivedMember ? CK_DerivedToBaseMemberPointer
2810                                 : CK_BaseToDerivedMemberPointer;
2811     C = EmitMemberPointerConversion(SrcTy, DstTy, CK, DerivedToBasePath.begin(),
2812                                     DerivedToBasePath.end(), C);
2813   }
2814   return C;
2815 }
2816 
2817 llvm::Constant *
2818 MicrosoftCXXABI::EmitMemberFunctionPointer(const CXXMethodDecl *MD) {
2819   assert(MD->isInstance() && "Member function must not be static!");
2820 
2821   CharUnits NonVirtualBaseAdjustment = CharUnits::Zero();
2822   const CXXRecordDecl *RD = MD->getParent()->getMostRecentNonInjectedDecl();
2823   CodeGenTypes &Types = CGM.getTypes();
2824 
2825   unsigned VBTableIndex = 0;
2826   llvm::Constant *FirstField;
2827   const FunctionProtoType *FPT = MD->getType()->castAs<FunctionProtoType>();
2828   if (!MD->isVirtual()) {
2829     llvm::Type *Ty;
2830     // Check whether the function has a computable LLVM signature.
2831     if (Types.isFuncTypeConvertible(FPT)) {
2832       // The function has a computable LLVM signature; use the correct type.
2833       Ty = Types.GetFunctionType(Types.arrangeCXXMethodDeclaration(MD));
2834     } else {
2835       // Use an arbitrary non-function type to tell GetAddrOfFunction that the
2836       // function type is incomplete.
2837       Ty = CGM.PtrDiffTy;
2838     }
2839     FirstField = CGM.GetAddrOfFunction(MD, Ty);
2840   } else {
2841     auto &VTableContext = CGM.getMicrosoftVTableContext();
2842     MethodVFTableLocation ML = VTableContext.getMethodVFTableLocation(MD);
2843     FirstField = EmitVirtualMemPtrThunk(MD, ML);
2844     // Include the vfptr adjustment if the method is in a non-primary vftable.
2845     NonVirtualBaseAdjustment += ML.VFPtrOffset;
2846     if (ML.VBase)
2847       VBTableIndex = VTableContext.getVBTableIndex(RD, ML.VBase) * 4;
2848   }
2849 
2850   if (VBTableIndex == 0 &&
2851       RD->getMSInheritanceModel() ==
2852           MSInheritanceModel::Virtual)
2853     NonVirtualBaseAdjustment -= getContext().getOffsetOfBaseWithVBPtr(RD);
2854 
2855   // The rest of the fields are common with data member pointers.
2856   FirstField = llvm::ConstantExpr::getBitCast(FirstField, CGM.VoidPtrTy);
2857   return EmitFullMemberPointer(FirstField, /*IsMemberFunction=*/true, RD,
2858                                NonVirtualBaseAdjustment, VBTableIndex);
2859 }
2860 
2861 /// Member pointers are the same if they're either bitwise identical *or* both
2862 /// null.  Null-ness for function members is determined by the first field,
2863 /// while for data member pointers we must compare all fields.
2864 llvm::Value *
2865 MicrosoftCXXABI::EmitMemberPointerComparison(CodeGenFunction &CGF,
2866                                              llvm::Value *L,
2867                                              llvm::Value *R,
2868                                              const MemberPointerType *MPT,
2869                                              bool Inequality) {
2870   CGBuilderTy &Builder = CGF.Builder;
2871 
2872   // Handle != comparisons by switching the sense of all boolean operations.
2873   llvm::ICmpInst::Predicate Eq;
2874   llvm::Instruction::BinaryOps And, Or;
2875   if (Inequality) {
2876     Eq = llvm::ICmpInst::ICMP_NE;
2877     And = llvm::Instruction::Or;
2878     Or = llvm::Instruction::And;
2879   } else {
2880     Eq = llvm::ICmpInst::ICMP_EQ;
2881     And = llvm::Instruction::And;
2882     Or = llvm::Instruction::Or;
2883   }
2884 
2885   // If this is a single field member pointer (single inheritance), this is a
2886   // single icmp.
2887   const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();
2888   MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
2889   if (inheritanceModelHasOnlyOneField(MPT->isMemberFunctionPointer(),
2890                                       Inheritance))
2891     return Builder.CreateICmp(Eq, L, R);
2892 
2893   // Compare the first field.
2894   llvm::Value *L0 = Builder.CreateExtractValue(L, 0, "lhs.0");
2895   llvm::Value *R0 = Builder.CreateExtractValue(R, 0, "rhs.0");
2896   llvm::Value *Cmp0 = Builder.CreateICmp(Eq, L0, R0, "memptr.cmp.first");
2897 
2898   // Compare everything other than the first field.
2899   llvm::Value *Res = nullptr;
2900   llvm::StructType *LType = cast<llvm::StructType>(L->getType());
2901   for (unsigned I = 1, E = LType->getNumElements(); I != E; ++I) {
2902     llvm::Value *LF = Builder.CreateExtractValue(L, I);
2903     llvm::Value *RF = Builder.CreateExtractValue(R, I);
2904     llvm::Value *Cmp = Builder.CreateICmp(Eq, LF, RF, "memptr.cmp.rest");
2905     if (Res)
2906       Res = Builder.CreateBinOp(And, Res, Cmp);
2907     else
2908       Res = Cmp;
2909   }
2910 
2911   // Check if the first field is 0 if this is a function pointer.
2912   if (MPT->isMemberFunctionPointer()) {
2913     // (l1 == r1 && ...) || l0 == 0
2914     llvm::Value *Zero = llvm::Constant::getNullValue(L0->getType());
2915     llvm::Value *IsZero = Builder.CreateICmp(Eq, L0, Zero, "memptr.cmp.iszero");
2916     Res = Builder.CreateBinOp(Or, Res, IsZero);
2917   }
2918 
2919   // Combine the comparison of the first field, which must always be true for
2920   // this comparison to succeeed.
2921   return Builder.CreateBinOp(And, Res, Cmp0, "memptr.cmp");
2922 }
2923 
2924 llvm::Value *
2925 MicrosoftCXXABI::EmitMemberPointerIsNotNull(CodeGenFunction &CGF,
2926                                             llvm::Value *MemPtr,
2927                                             const MemberPointerType *MPT) {
2928   CGBuilderTy &Builder = CGF.Builder;
2929   llvm::SmallVector<llvm::Constant *, 4> fields;
2930   // We only need one field for member functions.
2931   if (MPT->isMemberFunctionPointer())
2932     fields.push_back(llvm::Constant::getNullValue(CGM.VoidPtrTy));
2933   else
2934     GetNullMemberPointerFields(MPT, fields);
2935   assert(!fields.empty());
2936   llvm::Value *FirstField = MemPtr;
2937   if (MemPtr->getType()->isStructTy())
2938     FirstField = Builder.CreateExtractValue(MemPtr, 0);
2939   llvm::Value *Res = Builder.CreateICmpNE(FirstField, fields[0], "memptr.cmp0");
2940 
2941   // For function member pointers, we only need to test the function pointer
2942   // field.  The other fields if any can be garbage.
2943   if (MPT->isMemberFunctionPointer())
2944     return Res;
2945 
2946   // Otherwise, emit a series of compares and combine the results.
2947   for (int I = 1, E = fields.size(); I < E; ++I) {
2948     llvm::Value *Field = Builder.CreateExtractValue(MemPtr, I);
2949     llvm::Value *Next = Builder.CreateICmpNE(Field, fields[I], "memptr.cmp");
2950     Res = Builder.CreateOr(Res, Next, "memptr.tobool");
2951   }
2952   return Res;
2953 }
2954 
2955 bool MicrosoftCXXABI::MemberPointerConstantIsNull(const MemberPointerType *MPT,
2956                                                   llvm::Constant *Val) {
2957   // Function pointers are null if the pointer in the first field is null.
2958   if (MPT->isMemberFunctionPointer()) {
2959     llvm::Constant *FirstField = Val->getType()->isStructTy() ?
2960       Val->getAggregateElement(0U) : Val;
2961     return FirstField->isNullValue();
2962   }
2963 
2964   // If it's not a function pointer and it's zero initializable, we can easily
2965   // check zero.
2966   if (isZeroInitializable(MPT) && Val->isNullValue())
2967     return true;
2968 
2969   // Otherwise, break down all the fields for comparison.  Hopefully these
2970   // little Constants are reused, while a big null struct might not be.
2971   llvm::SmallVector<llvm::Constant *, 4> Fields;
2972   GetNullMemberPointerFields(MPT, Fields);
2973   if (Fields.size() == 1) {
2974     assert(Val->getType()->isIntegerTy());
2975     return Val == Fields[0];
2976   }
2977 
2978   unsigned I, E;
2979   for (I = 0, E = Fields.size(); I != E; ++I) {
2980     if (Val->getAggregateElement(I) != Fields[I])
2981       break;
2982   }
2983   return I == E;
2984 }
2985 
2986 llvm::Value *
2987 MicrosoftCXXABI::GetVBaseOffsetFromVBPtr(CodeGenFunction &CGF,
2988                                          Address This,
2989                                          llvm::Value *VBPtrOffset,
2990                                          llvm::Value *VBTableOffset,
2991                                          llvm::Value **VBPtrOut) {
2992   CGBuilderTy &Builder = CGF.Builder;
2993   // Load the vbtable pointer from the vbptr in the instance.
2994   This = Builder.CreateElementBitCast(This, CGM.Int8Ty);
2995   llvm::Value *VBPtr =
2996     Builder.CreateInBoundsGEP(This.getPointer(), VBPtrOffset, "vbptr");
2997   if (VBPtrOut) *VBPtrOut = VBPtr;
2998   VBPtr = Builder.CreateBitCast(VBPtr,
2999             CGM.Int32Ty->getPointerTo(0)->getPointerTo(This.getAddressSpace()));
3000 
3001   CharUnits VBPtrAlign;
3002   if (auto CI = dyn_cast<llvm::ConstantInt>(VBPtrOffset)) {
3003     VBPtrAlign = This.getAlignment().alignmentAtOffset(
3004                                    CharUnits::fromQuantity(CI->getSExtValue()));
3005   } else {
3006     VBPtrAlign = CGF.getPointerAlign();
3007   }
3008 
3009   llvm::Value *VBTable = Builder.CreateAlignedLoad(VBPtr, VBPtrAlign, "vbtable");
3010 
3011   // Translate from byte offset to table index. It improves analyzability.
3012   llvm::Value *VBTableIndex = Builder.CreateAShr(
3013       VBTableOffset, llvm::ConstantInt::get(VBTableOffset->getType(), 2),
3014       "vbtindex", /*isExact=*/true);
3015 
3016   // Load an i32 offset from the vb-table.
3017   llvm::Value *VBaseOffs = Builder.CreateInBoundsGEP(VBTable, VBTableIndex);
3018   VBaseOffs = Builder.CreateBitCast(VBaseOffs, CGM.Int32Ty->getPointerTo(0));
3019   return Builder.CreateAlignedLoad(VBaseOffs, CharUnits::fromQuantity(4),
3020                                    "vbase_offs");
3021 }
3022 
3023 // Returns an adjusted base cast to i8*, since we do more address arithmetic on
3024 // it.
3025 llvm::Value *MicrosoftCXXABI::AdjustVirtualBase(
3026     CodeGenFunction &CGF, const Expr *E, const CXXRecordDecl *RD,
3027     Address Base, llvm::Value *VBTableOffset, llvm::Value *VBPtrOffset) {
3028   CGBuilderTy &Builder = CGF.Builder;
3029   Base = Builder.CreateElementBitCast(Base, CGM.Int8Ty);
3030   llvm::BasicBlock *OriginalBB = nullptr;
3031   llvm::BasicBlock *SkipAdjustBB = nullptr;
3032   llvm::BasicBlock *VBaseAdjustBB = nullptr;
3033 
3034   // In the unspecified inheritance model, there might not be a vbtable at all,
3035   // in which case we need to skip the virtual base lookup.  If there is a
3036   // vbtable, the first entry is a no-op entry that gives back the original
3037   // base, so look for a virtual base adjustment offset of zero.
3038   if (VBPtrOffset) {
3039     OriginalBB = Builder.GetInsertBlock();
3040     VBaseAdjustBB = CGF.createBasicBlock("memptr.vadjust");
3041     SkipAdjustBB = CGF.createBasicBlock("memptr.skip_vadjust");
3042     llvm::Value *IsVirtual =
3043       Builder.CreateICmpNE(VBTableOffset, getZeroInt(),
3044                            "memptr.is_vbase");
3045     Builder.CreateCondBr(IsVirtual, VBaseAdjustBB, SkipAdjustBB);
3046     CGF.EmitBlock(VBaseAdjustBB);
3047   }
3048 
3049   // If we weren't given a dynamic vbptr offset, RD should be complete and we'll
3050   // know the vbptr offset.
3051   if (!VBPtrOffset) {
3052     CharUnits offs = CharUnits::Zero();
3053     if (!RD->hasDefinition()) {
3054       DiagnosticsEngine &Diags = CGF.CGM.getDiags();
3055       unsigned DiagID = Diags.getCustomDiagID(
3056           DiagnosticsEngine::Error,
3057           "member pointer representation requires a "
3058           "complete class type for %0 to perform this expression");
3059       Diags.Report(E->getExprLoc(), DiagID) << RD << E->getSourceRange();
3060     } else if (RD->getNumVBases())
3061       offs = getContext().getASTRecordLayout(RD).getVBPtrOffset();
3062     VBPtrOffset = llvm::ConstantInt::get(CGM.IntTy, offs.getQuantity());
3063   }
3064   llvm::Value *VBPtr = nullptr;
3065   llvm::Value *VBaseOffs =
3066     GetVBaseOffsetFromVBPtr(CGF, Base, VBPtrOffset, VBTableOffset, &VBPtr);
3067   llvm::Value *AdjustedBase = Builder.CreateInBoundsGEP(VBPtr, VBaseOffs);
3068 
3069   // Merge control flow with the case where we didn't have to adjust.
3070   if (VBaseAdjustBB) {
3071     Builder.CreateBr(SkipAdjustBB);
3072     CGF.EmitBlock(SkipAdjustBB);
3073     llvm::PHINode *Phi = Builder.CreatePHI(CGM.Int8PtrTy, 2, "memptr.base");
3074     Phi->addIncoming(Base.getPointer(), OriginalBB);
3075     Phi->addIncoming(AdjustedBase, VBaseAdjustBB);
3076     return Phi;
3077   }
3078   return AdjustedBase;
3079 }
3080 
3081 llvm::Value *MicrosoftCXXABI::EmitMemberDataPointerAddress(
3082     CodeGenFunction &CGF, const Expr *E, Address Base, llvm::Value *MemPtr,
3083     const MemberPointerType *MPT) {
3084   assert(MPT->isMemberDataPointer());
3085   unsigned AS = Base.getAddressSpace();
3086   llvm::Type *PType =
3087       CGF.ConvertTypeForMem(MPT->getPointeeType())->getPointerTo(AS);
3088   CGBuilderTy &Builder = CGF.Builder;
3089   const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();
3090   MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
3091 
3092   // Extract the fields we need, regardless of model.  We'll apply them if we
3093   // have them.
3094   llvm::Value *FieldOffset = MemPtr;
3095   llvm::Value *VirtualBaseAdjustmentOffset = nullptr;
3096   llvm::Value *VBPtrOffset = nullptr;
3097   if (MemPtr->getType()->isStructTy()) {
3098     // We need to extract values.
3099     unsigned I = 0;
3100     FieldOffset = Builder.CreateExtractValue(MemPtr, I++);
3101     if (inheritanceModelHasVBPtrOffsetField(Inheritance))
3102       VBPtrOffset = Builder.CreateExtractValue(MemPtr, I++);
3103     if (inheritanceModelHasVBTableOffsetField(Inheritance))
3104       VirtualBaseAdjustmentOffset = Builder.CreateExtractValue(MemPtr, I++);
3105   }
3106 
3107   llvm::Value *Addr;
3108   if (VirtualBaseAdjustmentOffset) {
3109     Addr = AdjustVirtualBase(CGF, E, RD, Base, VirtualBaseAdjustmentOffset,
3110                              VBPtrOffset);
3111   } else {
3112     Addr = Base.getPointer();
3113   }
3114 
3115   // Cast to char*.
3116   Addr = Builder.CreateBitCast(Addr, CGF.Int8Ty->getPointerTo(AS));
3117 
3118   // Apply the offset, which we assume is non-null.
3119   Addr = Builder.CreateInBoundsGEP(Addr, FieldOffset, "memptr.offset");
3120 
3121   // Cast the address to the appropriate pointer type, adopting the address
3122   // space of the base pointer.
3123   return Builder.CreateBitCast(Addr, PType);
3124 }
3125 
3126 llvm::Value *
3127 MicrosoftCXXABI::EmitMemberPointerConversion(CodeGenFunction &CGF,
3128                                              const CastExpr *E,
3129                                              llvm::Value *Src) {
3130   assert(E->getCastKind() == CK_DerivedToBaseMemberPointer ||
3131          E->getCastKind() == CK_BaseToDerivedMemberPointer ||
3132          E->getCastKind() == CK_ReinterpretMemberPointer);
3133 
3134   // Use constant emission if we can.
3135   if (isa<llvm::Constant>(Src))
3136     return EmitMemberPointerConversion(E, cast<llvm::Constant>(Src));
3137 
3138   // We may be adding or dropping fields from the member pointer, so we need
3139   // both types and the inheritance models of both records.
3140   const MemberPointerType *SrcTy =
3141     E->getSubExpr()->getType()->castAs<MemberPointerType>();
3142   const MemberPointerType *DstTy = E->getType()->castAs<MemberPointerType>();
3143   bool IsFunc = SrcTy->isMemberFunctionPointer();
3144 
3145   // If the classes use the same null representation, reinterpret_cast is a nop.
3146   bool IsReinterpret = E->getCastKind() == CK_ReinterpretMemberPointer;
3147   if (IsReinterpret && IsFunc)
3148     return Src;
3149 
3150   CXXRecordDecl *SrcRD = SrcTy->getMostRecentCXXRecordDecl();
3151   CXXRecordDecl *DstRD = DstTy->getMostRecentCXXRecordDecl();
3152   if (IsReinterpret &&
3153       SrcRD->nullFieldOffsetIsZero() == DstRD->nullFieldOffsetIsZero())
3154     return Src;
3155 
3156   CGBuilderTy &Builder = CGF.Builder;
3157 
3158   // Branch past the conversion if Src is null.
3159   llvm::Value *IsNotNull = EmitMemberPointerIsNotNull(CGF, Src, SrcTy);
3160   llvm::Constant *DstNull = EmitNullMemberPointer(DstTy);
3161 
3162   // C++ 5.2.10p9: The null member pointer value is converted to the null member
3163   //   pointer value of the destination type.
3164   if (IsReinterpret) {
3165     // For reinterpret casts, sema ensures that src and dst are both functions
3166     // or data and have the same size, which means the LLVM types should match.
3167     assert(Src->getType() == DstNull->getType());
3168     return Builder.CreateSelect(IsNotNull, Src, DstNull);
3169   }
3170 
3171   llvm::BasicBlock *OriginalBB = Builder.GetInsertBlock();
3172   llvm::BasicBlock *ConvertBB = CGF.createBasicBlock("memptr.convert");
3173   llvm::BasicBlock *ContinueBB = CGF.createBasicBlock("memptr.converted");
3174   Builder.CreateCondBr(IsNotNull, ConvertBB, ContinueBB);
3175   CGF.EmitBlock(ConvertBB);
3176 
3177   llvm::Value *Dst = EmitNonNullMemberPointerConversion(
3178       SrcTy, DstTy, E->getCastKind(), E->path_begin(), E->path_end(), Src,
3179       Builder);
3180 
3181   Builder.CreateBr(ContinueBB);
3182 
3183   // In the continuation, choose between DstNull and Dst.
3184   CGF.EmitBlock(ContinueBB);
3185   llvm::PHINode *Phi = Builder.CreatePHI(DstNull->getType(), 2, "memptr.converted");
3186   Phi->addIncoming(DstNull, OriginalBB);
3187   Phi->addIncoming(Dst, ConvertBB);
3188   return Phi;
3189 }
3190 
3191 llvm::Value *MicrosoftCXXABI::EmitNonNullMemberPointerConversion(
3192     const MemberPointerType *SrcTy, const MemberPointerType *DstTy, CastKind CK,
3193     CastExpr::path_const_iterator PathBegin,
3194     CastExpr::path_const_iterator PathEnd, llvm::Value *Src,
3195     CGBuilderTy &Builder) {
3196   const CXXRecordDecl *SrcRD = SrcTy->getMostRecentCXXRecordDecl();
3197   const CXXRecordDecl *DstRD = DstTy->getMostRecentCXXRecordDecl();
3198   MSInheritanceModel SrcInheritance = SrcRD->getMSInheritanceModel();
3199   MSInheritanceModel DstInheritance = DstRD->getMSInheritanceModel();
3200   bool IsFunc = SrcTy->isMemberFunctionPointer();
3201   bool IsConstant = isa<llvm::Constant>(Src);
3202 
3203   // Decompose src.
3204   llvm::Value *FirstField = Src;
3205   llvm::Value *NonVirtualBaseAdjustment = getZeroInt();
3206   llvm::Value *VirtualBaseAdjustmentOffset = getZeroInt();
3207   llvm::Value *VBPtrOffset = getZeroInt();
3208   if (!inheritanceModelHasOnlyOneField(IsFunc, SrcInheritance)) {
3209     // We need to extract values.
3210     unsigned I = 0;
3211     FirstField = Builder.CreateExtractValue(Src, I++);
3212     if (inheritanceModelHasNVOffsetField(IsFunc, SrcInheritance))
3213       NonVirtualBaseAdjustment = Builder.CreateExtractValue(Src, I++);
3214     if (inheritanceModelHasVBPtrOffsetField(SrcInheritance))
3215       VBPtrOffset = Builder.CreateExtractValue(Src, I++);
3216     if (inheritanceModelHasVBTableOffsetField(SrcInheritance))
3217       VirtualBaseAdjustmentOffset = Builder.CreateExtractValue(Src, I++);
3218   }
3219 
3220   bool IsDerivedToBase = (CK == CK_DerivedToBaseMemberPointer);
3221   const MemberPointerType *DerivedTy = IsDerivedToBase ? SrcTy : DstTy;
3222   const CXXRecordDecl *DerivedClass = DerivedTy->getMostRecentCXXRecordDecl();
3223 
3224   // For data pointers, we adjust the field offset directly.  For functions, we
3225   // have a separate field.
3226   llvm::Value *&NVAdjustField = IsFunc ? NonVirtualBaseAdjustment : FirstField;
3227 
3228   // The virtual inheritance model has a quirk: the virtual base table is always
3229   // referenced when dereferencing a member pointer even if the member pointer
3230   // is non-virtual.  This is accounted for by adjusting the non-virtual offset
3231   // to point backwards to the top of the MDC from the first VBase.  Undo this
3232   // adjustment to normalize the member pointer.
3233   llvm::Value *SrcVBIndexEqZero =
3234       Builder.CreateICmpEQ(VirtualBaseAdjustmentOffset, getZeroInt());
3235   if (SrcInheritance == MSInheritanceModel::Virtual) {
3236     if (int64_t SrcOffsetToFirstVBase =
3237             getContext().getOffsetOfBaseWithVBPtr(SrcRD).getQuantity()) {
3238       llvm::Value *UndoSrcAdjustment = Builder.CreateSelect(
3239           SrcVBIndexEqZero,
3240           llvm::ConstantInt::get(CGM.IntTy, SrcOffsetToFirstVBase),
3241           getZeroInt());
3242       NVAdjustField = Builder.CreateNSWAdd(NVAdjustField, UndoSrcAdjustment);
3243     }
3244   }
3245 
3246   // A non-zero vbindex implies that we are dealing with a source member in a
3247   // floating virtual base in addition to some non-virtual offset.  If the
3248   // vbindex is zero, we are dealing with a source that exists in a non-virtual,
3249   // fixed, base.  The difference between these two cases is that the vbindex +
3250   // nvoffset *always* point to the member regardless of what context they are
3251   // evaluated in so long as the vbindex is adjusted.  A member inside a fixed
3252   // base requires explicit nv adjustment.
3253   llvm::Constant *BaseClassOffset = llvm::ConstantInt::get(
3254       CGM.IntTy,
3255       CGM.computeNonVirtualBaseClassOffset(DerivedClass, PathBegin, PathEnd)
3256           .getQuantity());
3257 
3258   llvm::Value *NVDisp;
3259   if (IsDerivedToBase)
3260     NVDisp = Builder.CreateNSWSub(NVAdjustField, BaseClassOffset, "adj");
3261   else
3262     NVDisp = Builder.CreateNSWAdd(NVAdjustField, BaseClassOffset, "adj");
3263 
3264   NVAdjustField = Builder.CreateSelect(SrcVBIndexEqZero, NVDisp, getZeroInt());
3265 
3266   // Update the vbindex to an appropriate value in the destination because
3267   // SrcRD's vbtable might not be a strict prefix of the one in DstRD.
3268   llvm::Value *DstVBIndexEqZero = SrcVBIndexEqZero;
3269   if (inheritanceModelHasVBTableOffsetField(DstInheritance) &&
3270       inheritanceModelHasVBTableOffsetField(SrcInheritance)) {
3271     if (llvm::GlobalVariable *VDispMap =
3272             getAddrOfVirtualDisplacementMap(SrcRD, DstRD)) {
3273       llvm::Value *VBIndex = Builder.CreateExactUDiv(
3274           VirtualBaseAdjustmentOffset, llvm::ConstantInt::get(CGM.IntTy, 4));
3275       if (IsConstant) {
3276         llvm::Constant *Mapping = VDispMap->getInitializer();
3277         VirtualBaseAdjustmentOffset =
3278             Mapping->getAggregateElement(cast<llvm::Constant>(VBIndex));
3279       } else {
3280         llvm::Value *Idxs[] = {getZeroInt(), VBIndex};
3281         VirtualBaseAdjustmentOffset =
3282             Builder.CreateAlignedLoad(Builder.CreateInBoundsGEP(VDispMap, Idxs),
3283                                       CharUnits::fromQuantity(4));
3284       }
3285 
3286       DstVBIndexEqZero =
3287           Builder.CreateICmpEQ(VirtualBaseAdjustmentOffset, getZeroInt());
3288     }
3289   }
3290 
3291   // Set the VBPtrOffset to zero if the vbindex is zero.  Otherwise, initialize
3292   // it to the offset of the vbptr.
3293   if (inheritanceModelHasVBPtrOffsetField(DstInheritance)) {
3294     llvm::Value *DstVBPtrOffset = llvm::ConstantInt::get(
3295         CGM.IntTy,
3296         getContext().getASTRecordLayout(DstRD).getVBPtrOffset().getQuantity());
3297     VBPtrOffset =
3298         Builder.CreateSelect(DstVBIndexEqZero, getZeroInt(), DstVBPtrOffset);
3299   }
3300 
3301   // Likewise, apply a similar adjustment so that dereferencing the member
3302   // pointer correctly accounts for the distance between the start of the first
3303   // virtual base and the top of the MDC.
3304   if (DstInheritance == MSInheritanceModel::Virtual) {
3305     if (int64_t DstOffsetToFirstVBase =
3306             getContext().getOffsetOfBaseWithVBPtr(DstRD).getQuantity()) {
3307       llvm::Value *DoDstAdjustment = Builder.CreateSelect(
3308           DstVBIndexEqZero,
3309           llvm::ConstantInt::get(CGM.IntTy, DstOffsetToFirstVBase),
3310           getZeroInt());
3311       NVAdjustField = Builder.CreateNSWSub(NVAdjustField, DoDstAdjustment);
3312     }
3313   }
3314 
3315   // Recompose dst from the null struct and the adjusted fields from src.
3316   llvm::Value *Dst;
3317   if (inheritanceModelHasOnlyOneField(IsFunc, DstInheritance)) {
3318     Dst = FirstField;
3319   } else {
3320     Dst = llvm::UndefValue::get(ConvertMemberPointerType(DstTy));
3321     unsigned Idx = 0;
3322     Dst = Builder.CreateInsertValue(Dst, FirstField, Idx++);
3323     if (inheritanceModelHasNVOffsetField(IsFunc, DstInheritance))
3324       Dst = Builder.CreateInsertValue(Dst, NonVirtualBaseAdjustment, Idx++);
3325     if (inheritanceModelHasVBPtrOffsetField(DstInheritance))
3326       Dst = Builder.CreateInsertValue(Dst, VBPtrOffset, Idx++);
3327     if (inheritanceModelHasVBTableOffsetField(DstInheritance))
3328       Dst = Builder.CreateInsertValue(Dst, VirtualBaseAdjustmentOffset, Idx++);
3329   }
3330   return Dst;
3331 }
3332 
3333 llvm::Constant *
3334 MicrosoftCXXABI::EmitMemberPointerConversion(const CastExpr *E,
3335                                              llvm::Constant *Src) {
3336   const MemberPointerType *SrcTy =
3337       E->getSubExpr()->getType()->castAs<MemberPointerType>();
3338   const MemberPointerType *DstTy = E->getType()->castAs<MemberPointerType>();
3339 
3340   CastKind CK = E->getCastKind();
3341 
3342   return EmitMemberPointerConversion(SrcTy, DstTy, CK, E->path_begin(),
3343                                      E->path_end(), Src);
3344 }
3345 
3346 llvm::Constant *MicrosoftCXXABI::EmitMemberPointerConversion(
3347     const MemberPointerType *SrcTy, const MemberPointerType *DstTy, CastKind CK,
3348     CastExpr::path_const_iterator PathBegin,
3349     CastExpr::path_const_iterator PathEnd, llvm::Constant *Src) {
3350   assert(CK == CK_DerivedToBaseMemberPointer ||
3351          CK == CK_BaseToDerivedMemberPointer ||
3352          CK == CK_ReinterpretMemberPointer);
3353   // If src is null, emit a new null for dst.  We can't return src because dst
3354   // might have a new representation.
3355   if (MemberPointerConstantIsNull(SrcTy, Src))
3356     return EmitNullMemberPointer(DstTy);
3357 
3358   // We don't need to do anything for reinterpret_casts of non-null member
3359   // pointers.  We should only get here when the two type representations have
3360   // the same size.
3361   if (CK == CK_ReinterpretMemberPointer)
3362     return Src;
3363 
3364   CGBuilderTy Builder(CGM, CGM.getLLVMContext());
3365   auto *Dst = cast<llvm::Constant>(EmitNonNullMemberPointerConversion(
3366       SrcTy, DstTy, CK, PathBegin, PathEnd, Src, Builder));
3367 
3368   return Dst;
3369 }
3370 
3371 CGCallee MicrosoftCXXABI::EmitLoadOfMemberFunctionPointer(
3372     CodeGenFunction &CGF, const Expr *E, Address This,
3373     llvm::Value *&ThisPtrForCall, llvm::Value *MemPtr,
3374     const MemberPointerType *MPT) {
3375   assert(MPT->isMemberFunctionPointer());
3376   const FunctionProtoType *FPT =
3377     MPT->getPointeeType()->castAs<FunctionProtoType>();
3378   const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();
3379   llvm::FunctionType *FTy = CGM.getTypes().GetFunctionType(
3380       CGM.getTypes().arrangeCXXMethodType(RD, FPT, /*FD=*/nullptr));
3381   CGBuilderTy &Builder = CGF.Builder;
3382 
3383   MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
3384 
3385   // Extract the fields we need, regardless of model.  We'll apply them if we
3386   // have them.
3387   llvm::Value *FunctionPointer = MemPtr;
3388   llvm::Value *NonVirtualBaseAdjustment = nullptr;
3389   llvm::Value *VirtualBaseAdjustmentOffset = nullptr;
3390   llvm::Value *VBPtrOffset = nullptr;
3391   if (MemPtr->getType()->isStructTy()) {
3392     // We need to extract values.
3393     unsigned I = 0;
3394     FunctionPointer = Builder.CreateExtractValue(MemPtr, I++);
3395     if (inheritanceModelHasNVOffsetField(MPT, Inheritance))
3396       NonVirtualBaseAdjustment = Builder.CreateExtractValue(MemPtr, I++);
3397     if (inheritanceModelHasVBPtrOffsetField(Inheritance))
3398       VBPtrOffset = Builder.CreateExtractValue(MemPtr, I++);
3399     if (inheritanceModelHasVBTableOffsetField(Inheritance))
3400       VirtualBaseAdjustmentOffset = Builder.CreateExtractValue(MemPtr, I++);
3401   }
3402 
3403   if (VirtualBaseAdjustmentOffset) {
3404     ThisPtrForCall = AdjustVirtualBase(CGF, E, RD, This,
3405                                    VirtualBaseAdjustmentOffset, VBPtrOffset);
3406   } else {
3407     ThisPtrForCall = This.getPointer();
3408   }
3409 
3410   if (NonVirtualBaseAdjustment) {
3411     // Apply the adjustment and cast back to the original struct type.
3412     llvm::Value *Ptr = Builder.CreateBitCast(ThisPtrForCall, CGF.Int8PtrTy);
3413     Ptr = Builder.CreateInBoundsGEP(Ptr, NonVirtualBaseAdjustment);
3414     ThisPtrForCall = Builder.CreateBitCast(Ptr, ThisPtrForCall->getType(),
3415                                            "this.adjusted");
3416   }
3417 
3418   FunctionPointer =
3419     Builder.CreateBitCast(FunctionPointer, FTy->getPointerTo());
3420   CGCallee Callee(FPT, FunctionPointer);
3421   return Callee;
3422 }
3423 
3424 CGCXXABI *clang::CodeGen::CreateMicrosoftCXXABI(CodeGenModule &CGM) {
3425   return new MicrosoftCXXABI(CGM);
3426 }
3427 
3428 // MS RTTI Overview:
3429 // The run time type information emitted by cl.exe contains 5 distinct types of
3430 // structures.  Many of them reference each other.
3431 //
3432 // TypeInfo:  Static classes that are returned by typeid.
3433 //
3434 // CompleteObjectLocator:  Referenced by vftables.  They contain information
3435 //   required for dynamic casting, including OffsetFromTop.  They also contain
3436 //   a reference to the TypeInfo for the type and a reference to the
3437 //   CompleteHierarchyDescriptor for the type.
3438 //
3439 // ClassHierarchyDescriptor: Contains information about a class hierarchy.
3440 //   Used during dynamic_cast to walk a class hierarchy.  References a base
3441 //   class array and the size of said array.
3442 //
3443 // BaseClassArray: Contains a list of classes in a hierarchy.  BaseClassArray is
3444 //   somewhat of a misnomer because the most derived class is also in the list
3445 //   as well as multiple copies of virtual bases (if they occur multiple times
3446 //   in the hierarchy.)  The BaseClassArray contains one BaseClassDescriptor for
3447 //   every path in the hierarchy, in pre-order depth first order.  Note, we do
3448 //   not declare a specific llvm type for BaseClassArray, it's merely an array
3449 //   of BaseClassDescriptor pointers.
3450 //
3451 // BaseClassDescriptor: Contains information about a class in a class hierarchy.
3452 //   BaseClassDescriptor is also somewhat of a misnomer for the same reason that
3453 //   BaseClassArray is.  It contains information about a class within a
3454 //   hierarchy such as: is this base is ambiguous and what is its offset in the
3455 //   vbtable.  The names of the BaseClassDescriptors have all of their fields
3456 //   mangled into them so they can be aggressively deduplicated by the linker.
3457 
3458 static llvm::GlobalVariable *getTypeInfoVTable(CodeGenModule &CGM) {
3459   StringRef MangledName("??_7type_info@@6B@");
3460   if (auto VTable = CGM.getModule().getNamedGlobal(MangledName))
3461     return VTable;
3462   return new llvm::GlobalVariable(CGM.getModule(), CGM.Int8PtrTy,
3463                                   /*isConstant=*/true,
3464                                   llvm::GlobalVariable::ExternalLinkage,
3465                                   /*Initializer=*/nullptr, MangledName);
3466 }
3467 
3468 namespace {
3469 
3470 /// A Helper struct that stores information about a class in a class
3471 /// hierarchy.  The information stored in these structs struct is used during
3472 /// the generation of ClassHierarchyDescriptors and BaseClassDescriptors.
3473 // During RTTI creation, MSRTTIClasses are stored in a contiguous array with
3474 // implicit depth first pre-order tree connectivity.  getFirstChild and
3475 // getNextSibling allow us to walk the tree efficiently.
3476 struct MSRTTIClass {
3477   enum {
3478     IsPrivateOnPath = 1 | 8,
3479     IsAmbiguous = 2,
3480     IsPrivate = 4,
3481     IsVirtual = 16,
3482     HasHierarchyDescriptor = 64
3483   };
3484   MSRTTIClass(const CXXRecordDecl *RD) : RD(RD) {}
3485   uint32_t initialize(const MSRTTIClass *Parent,
3486                       const CXXBaseSpecifier *Specifier);
3487 
3488   MSRTTIClass *getFirstChild() { return this + 1; }
3489   static MSRTTIClass *getNextChild(MSRTTIClass *Child) {
3490     return Child + 1 + Child->NumBases;
3491   }
3492 
3493   const CXXRecordDecl *RD, *VirtualRoot;
3494   uint32_t Flags, NumBases, OffsetInVBase;
3495 };
3496 
3497 /// Recursively initialize the base class array.
3498 uint32_t MSRTTIClass::initialize(const MSRTTIClass *Parent,
3499                                  const CXXBaseSpecifier *Specifier) {
3500   Flags = HasHierarchyDescriptor;
3501   if (!Parent) {
3502     VirtualRoot = nullptr;
3503     OffsetInVBase = 0;
3504   } else {
3505     if (Specifier->getAccessSpecifier() != AS_public)
3506       Flags |= IsPrivate | IsPrivateOnPath;
3507     if (Specifier->isVirtual()) {
3508       Flags |= IsVirtual;
3509       VirtualRoot = RD;
3510       OffsetInVBase = 0;
3511     } else {
3512       if (Parent->Flags & IsPrivateOnPath)
3513         Flags |= IsPrivateOnPath;
3514       VirtualRoot = Parent->VirtualRoot;
3515       OffsetInVBase = Parent->OffsetInVBase + RD->getASTContext()
3516           .getASTRecordLayout(Parent->RD).getBaseClassOffset(RD).getQuantity();
3517     }
3518   }
3519   NumBases = 0;
3520   MSRTTIClass *Child = getFirstChild();
3521   for (const CXXBaseSpecifier &Base : RD->bases()) {
3522     NumBases += Child->initialize(this, &Base) + 1;
3523     Child = getNextChild(Child);
3524   }
3525   return NumBases;
3526 }
3527 
3528 static llvm::GlobalValue::LinkageTypes getLinkageForRTTI(QualType Ty) {
3529   switch (Ty->getLinkage()) {
3530   case NoLinkage:
3531   case InternalLinkage:
3532   case UniqueExternalLinkage:
3533     return llvm::GlobalValue::InternalLinkage;
3534 
3535   case VisibleNoLinkage:
3536   case ModuleInternalLinkage:
3537   case ModuleLinkage:
3538   case ExternalLinkage:
3539     return llvm::GlobalValue::LinkOnceODRLinkage;
3540   }
3541   llvm_unreachable("Invalid linkage!");
3542 }
3543 
3544 /// An ephemeral helper class for building MS RTTI types.  It caches some
3545 /// calls to the module and information about the most derived class in a
3546 /// hierarchy.
3547 struct MSRTTIBuilder {
3548   enum {
3549     HasBranchingHierarchy = 1,
3550     HasVirtualBranchingHierarchy = 2,
3551     HasAmbiguousBases = 4
3552   };
3553 
3554   MSRTTIBuilder(MicrosoftCXXABI &ABI, const CXXRecordDecl *RD)
3555       : CGM(ABI.CGM), Context(CGM.getContext()),
3556         VMContext(CGM.getLLVMContext()), Module(CGM.getModule()), RD(RD),
3557         Linkage(getLinkageForRTTI(CGM.getContext().getTagDeclType(RD))),
3558         ABI(ABI) {}
3559 
3560   llvm::GlobalVariable *getBaseClassDescriptor(const MSRTTIClass &Classes);
3561   llvm::GlobalVariable *
3562   getBaseClassArray(SmallVectorImpl<MSRTTIClass> &Classes);
3563   llvm::GlobalVariable *getClassHierarchyDescriptor();
3564   llvm::GlobalVariable *getCompleteObjectLocator(const VPtrInfo &Info);
3565 
3566   CodeGenModule &CGM;
3567   ASTContext &Context;
3568   llvm::LLVMContext &VMContext;
3569   llvm::Module &Module;
3570   const CXXRecordDecl *RD;
3571   llvm::GlobalVariable::LinkageTypes Linkage;
3572   MicrosoftCXXABI &ABI;
3573 };
3574 
3575 } // namespace
3576 
3577 /// Recursively serializes a class hierarchy in pre-order depth first
3578 /// order.
3579 static void serializeClassHierarchy(SmallVectorImpl<MSRTTIClass> &Classes,
3580                                     const CXXRecordDecl *RD) {
3581   Classes.push_back(MSRTTIClass(RD));
3582   for (const CXXBaseSpecifier &Base : RD->bases())
3583     serializeClassHierarchy(Classes, Base.getType()->getAsCXXRecordDecl());
3584 }
3585 
3586 /// Find ambiguity among base classes.
3587 static void
3588 detectAmbiguousBases(SmallVectorImpl<MSRTTIClass> &Classes) {
3589   llvm::SmallPtrSet<const CXXRecordDecl *, 8> VirtualBases;
3590   llvm::SmallPtrSet<const CXXRecordDecl *, 8> UniqueBases;
3591   llvm::SmallPtrSet<const CXXRecordDecl *, 8> AmbiguousBases;
3592   for (MSRTTIClass *Class = &Classes.front(); Class <= &Classes.back();) {
3593     if ((Class->Flags & MSRTTIClass::IsVirtual) &&
3594         !VirtualBases.insert(Class->RD).second) {
3595       Class = MSRTTIClass::getNextChild(Class);
3596       continue;
3597     }
3598     if (!UniqueBases.insert(Class->RD).second)
3599       AmbiguousBases.insert(Class->RD);
3600     Class++;
3601   }
3602   if (AmbiguousBases.empty())
3603     return;
3604   for (MSRTTIClass &Class : Classes)
3605     if (AmbiguousBases.count(Class.RD))
3606       Class.Flags |= MSRTTIClass::IsAmbiguous;
3607 }
3608 
3609 llvm::GlobalVariable *MSRTTIBuilder::getClassHierarchyDescriptor() {
3610   SmallString<256> MangledName;
3611   {
3612     llvm::raw_svector_ostream Out(MangledName);
3613     ABI.getMangleContext().mangleCXXRTTIClassHierarchyDescriptor(RD, Out);
3614   }
3615 
3616   // Check to see if we've already declared this ClassHierarchyDescriptor.
3617   if (auto CHD = Module.getNamedGlobal(MangledName))
3618     return CHD;
3619 
3620   // Serialize the class hierarchy and initialize the CHD Fields.
3621   SmallVector<MSRTTIClass, 8> Classes;
3622   serializeClassHierarchy(Classes, RD);
3623   Classes.front().initialize(/*Parent=*/nullptr, /*Specifier=*/nullptr);
3624   detectAmbiguousBases(Classes);
3625   int Flags = 0;
3626   for (auto Class : Classes) {
3627     if (Class.RD->getNumBases() > 1)
3628       Flags |= HasBranchingHierarchy;
3629     // Note: cl.exe does not calculate "HasAmbiguousBases" correctly.  We
3630     // believe the field isn't actually used.
3631     if (Class.Flags & MSRTTIClass::IsAmbiguous)
3632       Flags |= HasAmbiguousBases;
3633   }
3634   if ((Flags & HasBranchingHierarchy) && RD->getNumVBases() != 0)
3635     Flags |= HasVirtualBranchingHierarchy;
3636   // These gep indices are used to get the address of the first element of the
3637   // base class array.
3638   llvm::Value *GEPIndices[] = {llvm::ConstantInt::get(CGM.IntTy, 0),
3639                                llvm::ConstantInt::get(CGM.IntTy, 0)};
3640 
3641   // Forward-declare the class hierarchy descriptor
3642   auto Type = ABI.getClassHierarchyDescriptorType();
3643   auto CHD = new llvm::GlobalVariable(Module, Type, /*isConstant=*/true, Linkage,
3644                                       /*Initializer=*/nullptr,
3645                                       MangledName);
3646   if (CHD->isWeakForLinker())
3647     CHD->setComdat(CGM.getModule().getOrInsertComdat(CHD->getName()));
3648 
3649   auto *Bases = getBaseClassArray(Classes);
3650 
3651   // Initialize the base class ClassHierarchyDescriptor.
3652   llvm::Constant *Fields[] = {
3653       llvm::ConstantInt::get(CGM.IntTy, 0), // reserved by the runtime
3654       llvm::ConstantInt::get(CGM.IntTy, Flags),
3655       llvm::ConstantInt::get(CGM.IntTy, Classes.size()),
3656       ABI.getImageRelativeConstant(llvm::ConstantExpr::getInBoundsGetElementPtr(
3657           Bases->getValueType(), Bases,
3658           llvm::ArrayRef<llvm::Value *>(GEPIndices))),
3659   };
3660   CHD->setInitializer(llvm::ConstantStruct::get(Type, Fields));
3661   return CHD;
3662 }
3663 
3664 llvm::GlobalVariable *
3665 MSRTTIBuilder::getBaseClassArray(SmallVectorImpl<MSRTTIClass> &Classes) {
3666   SmallString<256> MangledName;
3667   {
3668     llvm::raw_svector_ostream Out(MangledName);
3669     ABI.getMangleContext().mangleCXXRTTIBaseClassArray(RD, Out);
3670   }
3671 
3672   // Forward-declare the base class array.
3673   // cl.exe pads the base class array with 1 (in 32 bit mode) or 4 (in 64 bit
3674   // mode) bytes of padding.  We provide a pointer sized amount of padding by
3675   // adding +1 to Classes.size().  The sections have pointer alignment and are
3676   // marked pick-any so it shouldn't matter.
3677   llvm::Type *PtrType = ABI.getImageRelativeType(
3678       ABI.getBaseClassDescriptorType()->getPointerTo());
3679   auto *ArrType = llvm::ArrayType::get(PtrType, Classes.size() + 1);
3680   auto *BCA =
3681       new llvm::GlobalVariable(Module, ArrType,
3682                                /*isConstant=*/true, Linkage,
3683                                /*Initializer=*/nullptr, MangledName);
3684   if (BCA->isWeakForLinker())
3685     BCA->setComdat(CGM.getModule().getOrInsertComdat(BCA->getName()));
3686 
3687   // Initialize the BaseClassArray.
3688   SmallVector<llvm::Constant *, 8> BaseClassArrayData;
3689   for (MSRTTIClass &Class : Classes)
3690     BaseClassArrayData.push_back(
3691         ABI.getImageRelativeConstant(getBaseClassDescriptor(Class)));
3692   BaseClassArrayData.push_back(llvm::Constant::getNullValue(PtrType));
3693   BCA->setInitializer(llvm::ConstantArray::get(ArrType, BaseClassArrayData));
3694   return BCA;
3695 }
3696 
3697 llvm::GlobalVariable *
3698 MSRTTIBuilder::getBaseClassDescriptor(const MSRTTIClass &Class) {
3699   // Compute the fields for the BaseClassDescriptor.  They are computed up front
3700   // because they are mangled into the name of the object.
3701   uint32_t OffsetInVBTable = 0;
3702   int32_t VBPtrOffset = -1;
3703   if (Class.VirtualRoot) {
3704     auto &VTableContext = CGM.getMicrosoftVTableContext();
3705     OffsetInVBTable = VTableContext.getVBTableIndex(RD, Class.VirtualRoot) * 4;
3706     VBPtrOffset = Context.getASTRecordLayout(RD).getVBPtrOffset().getQuantity();
3707   }
3708 
3709   SmallString<256> MangledName;
3710   {
3711     llvm::raw_svector_ostream Out(MangledName);
3712     ABI.getMangleContext().mangleCXXRTTIBaseClassDescriptor(
3713         Class.RD, Class.OffsetInVBase, VBPtrOffset, OffsetInVBTable,
3714         Class.Flags, Out);
3715   }
3716 
3717   // Check to see if we've already declared this object.
3718   if (auto BCD = Module.getNamedGlobal(MangledName))
3719     return BCD;
3720 
3721   // Forward-declare the base class descriptor.
3722   auto Type = ABI.getBaseClassDescriptorType();
3723   auto BCD =
3724       new llvm::GlobalVariable(Module, Type, /*isConstant=*/true, Linkage,
3725                                /*Initializer=*/nullptr, MangledName);
3726   if (BCD->isWeakForLinker())
3727     BCD->setComdat(CGM.getModule().getOrInsertComdat(BCD->getName()));
3728 
3729   // Initialize the BaseClassDescriptor.
3730   llvm::Constant *Fields[] = {
3731       ABI.getImageRelativeConstant(
3732           ABI.getAddrOfRTTIDescriptor(Context.getTypeDeclType(Class.RD))),
3733       llvm::ConstantInt::get(CGM.IntTy, Class.NumBases),
3734       llvm::ConstantInt::get(CGM.IntTy, Class.OffsetInVBase),
3735       llvm::ConstantInt::get(CGM.IntTy, VBPtrOffset),
3736       llvm::ConstantInt::get(CGM.IntTy, OffsetInVBTable),
3737       llvm::ConstantInt::get(CGM.IntTy, Class.Flags),
3738       ABI.getImageRelativeConstant(
3739           MSRTTIBuilder(ABI, Class.RD).getClassHierarchyDescriptor()),
3740   };
3741   BCD->setInitializer(llvm::ConstantStruct::get(Type, Fields));
3742   return BCD;
3743 }
3744 
3745 llvm::GlobalVariable *
3746 MSRTTIBuilder::getCompleteObjectLocator(const VPtrInfo &Info) {
3747   SmallString<256> MangledName;
3748   {
3749     llvm::raw_svector_ostream Out(MangledName);
3750     ABI.getMangleContext().mangleCXXRTTICompleteObjectLocator(RD, Info.MangledPath, Out);
3751   }
3752 
3753   // Check to see if we've already computed this complete object locator.
3754   if (auto COL = Module.getNamedGlobal(MangledName))
3755     return COL;
3756 
3757   // Compute the fields of the complete object locator.
3758   int OffsetToTop = Info.FullOffsetInMDC.getQuantity();
3759   int VFPtrOffset = 0;
3760   // The offset includes the vtordisp if one exists.
3761   if (const CXXRecordDecl *VBase = Info.getVBaseWithVPtr())
3762     if (Context.getASTRecordLayout(RD)
3763       .getVBaseOffsetsMap()
3764       .find(VBase)
3765       ->second.hasVtorDisp())
3766       VFPtrOffset = Info.NonVirtualOffset.getQuantity() + 4;
3767 
3768   // Forward-declare the complete object locator.
3769   llvm::StructType *Type = ABI.getCompleteObjectLocatorType();
3770   auto COL = new llvm::GlobalVariable(Module, Type, /*isConstant=*/true, Linkage,
3771     /*Initializer=*/nullptr, MangledName);
3772 
3773   // Initialize the CompleteObjectLocator.
3774   llvm::Constant *Fields[] = {
3775       llvm::ConstantInt::get(CGM.IntTy, ABI.isImageRelative()),
3776       llvm::ConstantInt::get(CGM.IntTy, OffsetToTop),
3777       llvm::ConstantInt::get(CGM.IntTy, VFPtrOffset),
3778       ABI.getImageRelativeConstant(
3779           CGM.GetAddrOfRTTIDescriptor(Context.getTypeDeclType(RD))),
3780       ABI.getImageRelativeConstant(getClassHierarchyDescriptor()),
3781       ABI.getImageRelativeConstant(COL),
3782   };
3783   llvm::ArrayRef<llvm::Constant *> FieldsRef(Fields);
3784   if (!ABI.isImageRelative())
3785     FieldsRef = FieldsRef.drop_back();
3786   COL->setInitializer(llvm::ConstantStruct::get(Type, FieldsRef));
3787   if (COL->isWeakForLinker())
3788     COL->setComdat(CGM.getModule().getOrInsertComdat(COL->getName()));
3789   return COL;
3790 }
3791 
3792 static QualType decomposeTypeForEH(ASTContext &Context, QualType T,
3793                                    bool &IsConst, bool &IsVolatile,
3794                                    bool &IsUnaligned) {
3795   T = Context.getExceptionObjectType(T);
3796 
3797   // C++14 [except.handle]p3:
3798   //   A handler is a match for an exception object of type E if [...]
3799   //     - the handler is of type cv T or const T& where T is a pointer type and
3800   //       E is a pointer type that can be converted to T by [...]
3801   //         - a qualification conversion
3802   IsConst = false;
3803   IsVolatile = false;
3804   IsUnaligned = false;
3805   QualType PointeeType = T->getPointeeType();
3806   if (!PointeeType.isNull()) {
3807     IsConst = PointeeType.isConstQualified();
3808     IsVolatile = PointeeType.isVolatileQualified();
3809     IsUnaligned = PointeeType.getQualifiers().hasUnaligned();
3810   }
3811 
3812   // Member pointer types like "const int A::*" are represented by having RTTI
3813   // for "int A::*" and separately storing the const qualifier.
3814   if (const auto *MPTy = T->getAs<MemberPointerType>())
3815     T = Context.getMemberPointerType(PointeeType.getUnqualifiedType(),
3816                                      MPTy->getClass());
3817 
3818   // Pointer types like "const int * const *" are represented by having RTTI
3819   // for "const int **" and separately storing the const qualifier.
3820   if (T->isPointerType())
3821     T = Context.getPointerType(PointeeType.getUnqualifiedType());
3822 
3823   return T;
3824 }
3825 
3826 CatchTypeInfo
3827 MicrosoftCXXABI::getAddrOfCXXCatchHandlerType(QualType Type,
3828                                               QualType CatchHandlerType) {
3829   // TypeDescriptors for exceptions never have qualified pointer types,
3830   // qualifiers are stored separately in order to support qualification
3831   // conversions.
3832   bool IsConst, IsVolatile, IsUnaligned;
3833   Type =
3834       decomposeTypeForEH(getContext(), Type, IsConst, IsVolatile, IsUnaligned);
3835 
3836   bool IsReference = CatchHandlerType->isReferenceType();
3837 
3838   uint32_t Flags = 0;
3839   if (IsConst)
3840     Flags |= 1;
3841   if (IsVolatile)
3842     Flags |= 2;
3843   if (IsUnaligned)
3844     Flags |= 4;
3845   if (IsReference)
3846     Flags |= 8;
3847 
3848   return CatchTypeInfo{getAddrOfRTTIDescriptor(Type)->stripPointerCasts(),
3849                        Flags};
3850 }
3851 
3852 /// Gets a TypeDescriptor.  Returns a llvm::Constant * rather than a
3853 /// llvm::GlobalVariable * because different type descriptors have different
3854 /// types, and need to be abstracted.  They are abstracting by casting the
3855 /// address to an Int8PtrTy.
3856 llvm::Constant *MicrosoftCXXABI::getAddrOfRTTIDescriptor(QualType Type) {
3857   SmallString<256> MangledName;
3858   {
3859     llvm::raw_svector_ostream Out(MangledName);
3860     getMangleContext().mangleCXXRTTI(Type, Out);
3861   }
3862 
3863   // Check to see if we've already declared this TypeDescriptor.
3864   if (llvm::GlobalVariable *GV = CGM.getModule().getNamedGlobal(MangledName))
3865     return llvm::ConstantExpr::getBitCast(GV, CGM.Int8PtrTy);
3866 
3867   // Note for the future: If we would ever like to do deferred emission of
3868   // RTTI, check if emitting vtables opportunistically need any adjustment.
3869 
3870   // Compute the fields for the TypeDescriptor.
3871   SmallString<256> TypeInfoString;
3872   {
3873     llvm::raw_svector_ostream Out(TypeInfoString);
3874     getMangleContext().mangleCXXRTTIName(Type, Out);
3875   }
3876 
3877   // Declare and initialize the TypeDescriptor.
3878   llvm::Constant *Fields[] = {
3879     getTypeInfoVTable(CGM),                        // VFPtr
3880     llvm::ConstantPointerNull::get(CGM.Int8PtrTy), // Runtime data
3881     llvm::ConstantDataArray::getString(CGM.getLLVMContext(), TypeInfoString)};
3882   llvm::StructType *TypeDescriptorType =
3883       getTypeDescriptorType(TypeInfoString);
3884   auto *Var = new llvm::GlobalVariable(
3885       CGM.getModule(), TypeDescriptorType, /*isConstant=*/false,
3886       getLinkageForRTTI(Type),
3887       llvm::ConstantStruct::get(TypeDescriptorType, Fields),
3888       MangledName);
3889   if (Var->isWeakForLinker())
3890     Var->setComdat(CGM.getModule().getOrInsertComdat(Var->getName()));
3891   return llvm::ConstantExpr::getBitCast(Var, CGM.Int8PtrTy);
3892 }
3893 
3894 /// Gets or a creates a Microsoft CompleteObjectLocator.
3895 llvm::GlobalVariable *
3896 MicrosoftCXXABI::getMSCompleteObjectLocator(const CXXRecordDecl *RD,
3897                                             const VPtrInfo &Info) {
3898   return MSRTTIBuilder(*this, RD).getCompleteObjectLocator(Info);
3899 }
3900 
3901 void MicrosoftCXXABI::emitCXXStructor(GlobalDecl GD) {
3902   if (auto *ctor = dyn_cast<CXXConstructorDecl>(GD.getDecl())) {
3903     // There are no constructor variants, always emit the complete destructor.
3904     llvm::Function *Fn =
3905         CGM.codegenCXXStructor(GD.getWithCtorType(Ctor_Complete));
3906     CGM.maybeSetTrivialComdat(*ctor, *Fn);
3907     return;
3908   }
3909 
3910   auto *dtor = cast<CXXDestructorDecl>(GD.getDecl());
3911 
3912   // Emit the base destructor if the base and complete (vbase) destructors are
3913   // equivalent. This effectively implements -mconstructor-aliases as part of
3914   // the ABI.
3915   if (GD.getDtorType() == Dtor_Complete &&
3916       dtor->getParent()->getNumVBases() == 0)
3917     GD = GD.getWithDtorType(Dtor_Base);
3918 
3919   // The base destructor is equivalent to the base destructor of its
3920   // base class if there is exactly one non-virtual base class with a
3921   // non-trivial destructor, there are no fields with a non-trivial
3922   // destructor, and the body of the destructor is trivial.
3923   if (GD.getDtorType() == Dtor_Base && !CGM.TryEmitBaseDestructorAsAlias(dtor))
3924     return;
3925 
3926   llvm::Function *Fn = CGM.codegenCXXStructor(GD);
3927   if (Fn->isWeakForLinker())
3928     Fn->setComdat(CGM.getModule().getOrInsertComdat(Fn->getName()));
3929 }
3930 
3931 llvm::Function *
3932 MicrosoftCXXABI::getAddrOfCXXCtorClosure(const CXXConstructorDecl *CD,
3933                                          CXXCtorType CT) {
3934   assert(CT == Ctor_CopyingClosure || CT == Ctor_DefaultClosure);
3935 
3936   // Calculate the mangled name.
3937   SmallString<256> ThunkName;
3938   llvm::raw_svector_ostream Out(ThunkName);
3939   getMangleContext().mangleName(GlobalDecl(CD, CT), Out);
3940 
3941   // If the thunk has been generated previously, just return it.
3942   if (llvm::GlobalValue *GV = CGM.getModule().getNamedValue(ThunkName))
3943     return cast<llvm::Function>(GV);
3944 
3945   // Create the llvm::Function.
3946   const CGFunctionInfo &FnInfo = CGM.getTypes().arrangeMSCtorClosure(CD, CT);
3947   llvm::FunctionType *ThunkTy = CGM.getTypes().GetFunctionType(FnInfo);
3948   const CXXRecordDecl *RD = CD->getParent();
3949   QualType RecordTy = getContext().getRecordType(RD);
3950   llvm::Function *ThunkFn = llvm::Function::Create(
3951       ThunkTy, getLinkageForRTTI(RecordTy), ThunkName.str(), &CGM.getModule());
3952   ThunkFn->setCallingConv(static_cast<llvm::CallingConv::ID>(
3953       FnInfo.getEffectiveCallingConvention()));
3954   if (ThunkFn->isWeakForLinker())
3955     ThunkFn->setComdat(CGM.getModule().getOrInsertComdat(ThunkFn->getName()));
3956   bool IsCopy = CT == Ctor_CopyingClosure;
3957 
3958   // Start codegen.
3959   CodeGenFunction CGF(CGM);
3960   CGF.CurGD = GlobalDecl(CD, Ctor_Complete);
3961 
3962   // Build FunctionArgs.
3963   FunctionArgList FunctionArgs;
3964 
3965   // A constructor always starts with a 'this' pointer as its first argument.
3966   buildThisParam(CGF, FunctionArgs);
3967 
3968   // Following the 'this' pointer is a reference to the source object that we
3969   // are copying from.
3970   ImplicitParamDecl SrcParam(
3971       getContext(), /*DC=*/nullptr, SourceLocation(),
3972       &getContext().Idents.get("src"),
3973       getContext().getLValueReferenceType(RecordTy,
3974                                           /*SpelledAsLValue=*/true),
3975       ImplicitParamDecl::Other);
3976   if (IsCopy)
3977     FunctionArgs.push_back(&SrcParam);
3978 
3979   // Constructors for classes which utilize virtual bases have an additional
3980   // parameter which indicates whether or not it is being delegated to by a more
3981   // derived constructor.
3982   ImplicitParamDecl IsMostDerived(getContext(), /*DC=*/nullptr,
3983                                   SourceLocation(),
3984                                   &getContext().Idents.get("is_most_derived"),
3985                                   getContext().IntTy, ImplicitParamDecl::Other);
3986   // Only add the parameter to the list if the class has virtual bases.
3987   if (RD->getNumVBases() > 0)
3988     FunctionArgs.push_back(&IsMostDerived);
3989 
3990   // Start defining the function.
3991   auto NL = ApplyDebugLocation::CreateEmpty(CGF);
3992   CGF.StartFunction(GlobalDecl(), FnInfo.getReturnType(), ThunkFn, FnInfo,
3993                     FunctionArgs, CD->getLocation(), SourceLocation());
3994   // Create a scope with an artificial location for the body of this function.
3995   auto AL = ApplyDebugLocation::CreateArtificial(CGF);
3996   setCXXABIThisValue(CGF, loadIncomingCXXThis(CGF));
3997   llvm::Value *This = getThisValue(CGF);
3998 
3999   llvm::Value *SrcVal =
4000       IsCopy ? CGF.Builder.CreateLoad(CGF.GetAddrOfLocalVar(&SrcParam), "src")
4001              : nullptr;
4002 
4003   CallArgList Args;
4004 
4005   // Push the this ptr.
4006   Args.add(RValue::get(This), CD->getThisType());
4007 
4008   // Push the src ptr.
4009   if (SrcVal)
4010     Args.add(RValue::get(SrcVal), SrcParam.getType());
4011 
4012   // Add the rest of the default arguments.
4013   SmallVector<const Stmt *, 4> ArgVec;
4014   ArrayRef<ParmVarDecl *> params = CD->parameters().drop_front(IsCopy ? 1 : 0);
4015   for (const ParmVarDecl *PD : params) {
4016     assert(PD->hasDefaultArg() && "ctor closure lacks default args");
4017     ArgVec.push_back(PD->getDefaultArg());
4018   }
4019 
4020   CodeGenFunction::RunCleanupsScope Cleanups(CGF);
4021 
4022   const auto *FPT = CD->getType()->castAs<FunctionProtoType>();
4023   CGF.EmitCallArgs(Args, FPT, llvm::makeArrayRef(ArgVec), CD, IsCopy ? 1 : 0);
4024 
4025   // Insert any ABI-specific implicit constructor arguments.
4026   AddedStructorArgCounts ExtraArgs =
4027       addImplicitConstructorArgs(CGF, CD, Ctor_Complete,
4028                                  /*ForVirtualBase=*/false,
4029                                  /*Delegating=*/false, Args);
4030   // Call the destructor with our arguments.
4031   llvm::Constant *CalleePtr =
4032       CGM.getAddrOfCXXStructor(GlobalDecl(CD, Ctor_Complete));
4033   CGCallee Callee =
4034       CGCallee::forDirect(CalleePtr, GlobalDecl(CD, Ctor_Complete));
4035   const CGFunctionInfo &CalleeInfo = CGM.getTypes().arrangeCXXConstructorCall(
4036       Args, CD, Ctor_Complete, ExtraArgs.Prefix, ExtraArgs.Suffix);
4037   CGF.EmitCall(CalleeInfo, Callee, ReturnValueSlot(), Args);
4038 
4039   Cleanups.ForceCleanup();
4040 
4041   // Emit the ret instruction, remove any temporary instructions created for the
4042   // aid of CodeGen.
4043   CGF.FinishFunction(SourceLocation());
4044 
4045   return ThunkFn;
4046 }
4047 
4048 llvm::Constant *MicrosoftCXXABI::getCatchableType(QualType T,
4049                                                   uint32_t NVOffset,
4050                                                   int32_t VBPtrOffset,
4051                                                   uint32_t VBIndex) {
4052   assert(!T->isReferenceType());
4053 
4054   CXXRecordDecl *RD = T->getAsCXXRecordDecl();
4055   const CXXConstructorDecl *CD =
4056       RD ? CGM.getContext().getCopyConstructorForExceptionObject(RD) : nullptr;
4057   CXXCtorType CT = Ctor_Complete;
4058   if (CD)
4059     if (!hasDefaultCXXMethodCC(getContext(), CD) || CD->getNumParams() != 1)
4060       CT = Ctor_CopyingClosure;
4061 
4062   uint32_t Size = getContext().getTypeSizeInChars(T).getQuantity();
4063   SmallString<256> MangledName;
4064   {
4065     llvm::raw_svector_ostream Out(MangledName);
4066     getMangleContext().mangleCXXCatchableType(T, CD, CT, Size, NVOffset,
4067                                               VBPtrOffset, VBIndex, Out);
4068   }
4069   if (llvm::GlobalVariable *GV = CGM.getModule().getNamedGlobal(MangledName))
4070     return getImageRelativeConstant(GV);
4071 
4072   // The TypeDescriptor is used by the runtime to determine if a catch handler
4073   // is appropriate for the exception object.
4074   llvm::Constant *TD = getImageRelativeConstant(getAddrOfRTTIDescriptor(T));
4075 
4076   // The runtime is responsible for calling the copy constructor if the
4077   // exception is caught by value.
4078   llvm::Constant *CopyCtor;
4079   if (CD) {
4080     if (CT == Ctor_CopyingClosure)
4081       CopyCtor = getAddrOfCXXCtorClosure(CD, Ctor_CopyingClosure);
4082     else
4083       CopyCtor = CGM.getAddrOfCXXStructor(GlobalDecl(CD, Ctor_Complete));
4084 
4085     CopyCtor = llvm::ConstantExpr::getBitCast(CopyCtor, CGM.Int8PtrTy);
4086   } else {
4087     CopyCtor = llvm::Constant::getNullValue(CGM.Int8PtrTy);
4088   }
4089   CopyCtor = getImageRelativeConstant(CopyCtor);
4090 
4091   bool IsScalar = !RD;
4092   bool HasVirtualBases = false;
4093   bool IsStdBadAlloc = false; // std::bad_alloc is special for some reason.
4094   QualType PointeeType = T;
4095   if (T->isPointerType())
4096     PointeeType = T->getPointeeType();
4097   if (const CXXRecordDecl *RD = PointeeType->getAsCXXRecordDecl()) {
4098     HasVirtualBases = RD->getNumVBases() > 0;
4099     if (IdentifierInfo *II = RD->getIdentifier())
4100       IsStdBadAlloc = II->isStr("bad_alloc") && RD->isInStdNamespace();
4101   }
4102 
4103   // Encode the relevant CatchableType properties into the Flags bitfield.
4104   // FIXME: Figure out how bits 2 or 8 can get set.
4105   uint32_t Flags = 0;
4106   if (IsScalar)
4107     Flags |= 1;
4108   if (HasVirtualBases)
4109     Flags |= 4;
4110   if (IsStdBadAlloc)
4111     Flags |= 16;
4112 
4113   llvm::Constant *Fields[] = {
4114       llvm::ConstantInt::get(CGM.IntTy, Flags),       // Flags
4115       TD,                                             // TypeDescriptor
4116       llvm::ConstantInt::get(CGM.IntTy, NVOffset),    // NonVirtualAdjustment
4117       llvm::ConstantInt::get(CGM.IntTy, VBPtrOffset), // OffsetToVBPtr
4118       llvm::ConstantInt::get(CGM.IntTy, VBIndex),     // VBTableIndex
4119       llvm::ConstantInt::get(CGM.IntTy, Size),        // Size
4120       CopyCtor                                        // CopyCtor
4121   };
4122   llvm::StructType *CTType = getCatchableTypeType();
4123   auto *GV = new llvm::GlobalVariable(
4124       CGM.getModule(), CTType, /*isConstant=*/true, getLinkageForRTTI(T),
4125       llvm::ConstantStruct::get(CTType, Fields), MangledName);
4126   GV->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
4127   GV->setSection(".xdata");
4128   if (GV->isWeakForLinker())
4129     GV->setComdat(CGM.getModule().getOrInsertComdat(GV->getName()));
4130   return getImageRelativeConstant(GV);
4131 }
4132 
4133 llvm::GlobalVariable *MicrosoftCXXABI::getCatchableTypeArray(QualType T) {
4134   assert(!T->isReferenceType());
4135 
4136   // See if we've already generated a CatchableTypeArray for this type before.
4137   llvm::GlobalVariable *&CTA = CatchableTypeArrays[T];
4138   if (CTA)
4139     return CTA;
4140 
4141   // Ensure that we don't have duplicate entries in our CatchableTypeArray by
4142   // using a SmallSetVector.  Duplicates may arise due to virtual bases
4143   // occurring more than once in the hierarchy.
4144   llvm::SmallSetVector<llvm::Constant *, 2> CatchableTypes;
4145 
4146   // C++14 [except.handle]p3:
4147   //   A handler is a match for an exception object of type E if [...]
4148   //     - the handler is of type cv T or cv T& and T is an unambiguous public
4149   //       base class of E, or
4150   //     - the handler is of type cv T or const T& where T is a pointer type and
4151   //       E is a pointer type that can be converted to T by [...]
4152   //         - a standard pointer conversion (4.10) not involving conversions to
4153   //           pointers to private or protected or ambiguous classes
4154   const CXXRecordDecl *MostDerivedClass = nullptr;
4155   bool IsPointer = T->isPointerType();
4156   if (IsPointer)
4157     MostDerivedClass = T->getPointeeType()->getAsCXXRecordDecl();
4158   else
4159     MostDerivedClass = T->getAsCXXRecordDecl();
4160 
4161   // Collect all the unambiguous public bases of the MostDerivedClass.
4162   if (MostDerivedClass) {
4163     const ASTContext &Context = getContext();
4164     const ASTRecordLayout &MostDerivedLayout =
4165         Context.getASTRecordLayout(MostDerivedClass);
4166     MicrosoftVTableContext &VTableContext = CGM.getMicrosoftVTableContext();
4167     SmallVector<MSRTTIClass, 8> Classes;
4168     serializeClassHierarchy(Classes, MostDerivedClass);
4169     Classes.front().initialize(/*Parent=*/nullptr, /*Specifier=*/nullptr);
4170     detectAmbiguousBases(Classes);
4171     for (const MSRTTIClass &Class : Classes) {
4172       // Skip any ambiguous or private bases.
4173       if (Class.Flags &
4174           (MSRTTIClass::IsPrivateOnPath | MSRTTIClass::IsAmbiguous))
4175         continue;
4176       // Write down how to convert from a derived pointer to a base pointer.
4177       uint32_t OffsetInVBTable = 0;
4178       int32_t VBPtrOffset = -1;
4179       if (Class.VirtualRoot) {
4180         OffsetInVBTable =
4181           VTableContext.getVBTableIndex(MostDerivedClass, Class.VirtualRoot)*4;
4182         VBPtrOffset = MostDerivedLayout.getVBPtrOffset().getQuantity();
4183       }
4184 
4185       // Turn our record back into a pointer if the exception object is a
4186       // pointer.
4187       QualType RTTITy = QualType(Class.RD->getTypeForDecl(), 0);
4188       if (IsPointer)
4189         RTTITy = Context.getPointerType(RTTITy);
4190       CatchableTypes.insert(getCatchableType(RTTITy, Class.OffsetInVBase,
4191                                              VBPtrOffset, OffsetInVBTable));
4192     }
4193   }
4194 
4195   // C++14 [except.handle]p3:
4196   //   A handler is a match for an exception object of type E if
4197   //     - The handler is of type cv T or cv T& and E and T are the same type
4198   //       (ignoring the top-level cv-qualifiers)
4199   CatchableTypes.insert(getCatchableType(T));
4200 
4201   // C++14 [except.handle]p3:
4202   //   A handler is a match for an exception object of type E if
4203   //     - the handler is of type cv T or const T& where T is a pointer type and
4204   //       E is a pointer type that can be converted to T by [...]
4205   //         - a standard pointer conversion (4.10) not involving conversions to
4206   //           pointers to private or protected or ambiguous classes
4207   //
4208   // C++14 [conv.ptr]p2:
4209   //   A prvalue of type "pointer to cv T," where T is an object type, can be
4210   //   converted to a prvalue of type "pointer to cv void".
4211   if (IsPointer && T->getPointeeType()->isObjectType())
4212     CatchableTypes.insert(getCatchableType(getContext().VoidPtrTy));
4213 
4214   // C++14 [except.handle]p3:
4215   //   A handler is a match for an exception object of type E if [...]
4216   //     - the handler is of type cv T or const T& where T is a pointer or
4217   //       pointer to member type and E is std::nullptr_t.
4218   //
4219   // We cannot possibly list all possible pointer types here, making this
4220   // implementation incompatible with the standard.  However, MSVC includes an
4221   // entry for pointer-to-void in this case.  Let's do the same.
4222   if (T->isNullPtrType())
4223     CatchableTypes.insert(getCatchableType(getContext().VoidPtrTy));
4224 
4225   uint32_t NumEntries = CatchableTypes.size();
4226   llvm::Type *CTType =
4227       getImageRelativeType(getCatchableTypeType()->getPointerTo());
4228   llvm::ArrayType *AT = llvm::ArrayType::get(CTType, NumEntries);
4229   llvm::StructType *CTAType = getCatchableTypeArrayType(NumEntries);
4230   llvm::Constant *Fields[] = {
4231       llvm::ConstantInt::get(CGM.IntTy, NumEntries),    // NumEntries
4232       llvm::ConstantArray::get(
4233           AT, llvm::makeArrayRef(CatchableTypes.begin(),
4234                                  CatchableTypes.end())) // CatchableTypes
4235   };
4236   SmallString<256> MangledName;
4237   {
4238     llvm::raw_svector_ostream Out(MangledName);
4239     getMangleContext().mangleCXXCatchableTypeArray(T, NumEntries, Out);
4240   }
4241   CTA = new llvm::GlobalVariable(
4242       CGM.getModule(), CTAType, /*isConstant=*/true, getLinkageForRTTI(T),
4243       llvm::ConstantStruct::get(CTAType, Fields), MangledName);
4244   CTA->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
4245   CTA->setSection(".xdata");
4246   if (CTA->isWeakForLinker())
4247     CTA->setComdat(CGM.getModule().getOrInsertComdat(CTA->getName()));
4248   return CTA;
4249 }
4250 
4251 llvm::GlobalVariable *MicrosoftCXXABI::getThrowInfo(QualType T) {
4252   bool IsConst, IsVolatile, IsUnaligned;
4253   T = decomposeTypeForEH(getContext(), T, IsConst, IsVolatile, IsUnaligned);
4254 
4255   // The CatchableTypeArray enumerates the various (CV-unqualified) types that
4256   // the exception object may be caught as.
4257   llvm::GlobalVariable *CTA = getCatchableTypeArray(T);
4258   // The first field in a CatchableTypeArray is the number of CatchableTypes.
4259   // This is used as a component of the mangled name which means that we need to
4260   // know what it is in order to see if we have previously generated the
4261   // ThrowInfo.
4262   uint32_t NumEntries =
4263       cast<llvm::ConstantInt>(CTA->getInitializer()->getAggregateElement(0U))
4264           ->getLimitedValue();
4265 
4266   SmallString<256> MangledName;
4267   {
4268     llvm::raw_svector_ostream Out(MangledName);
4269     getMangleContext().mangleCXXThrowInfo(T, IsConst, IsVolatile, IsUnaligned,
4270                                           NumEntries, Out);
4271   }
4272 
4273   // Reuse a previously generated ThrowInfo if we have generated an appropriate
4274   // one before.
4275   if (llvm::GlobalVariable *GV = CGM.getModule().getNamedGlobal(MangledName))
4276     return GV;
4277 
4278   // The RTTI TypeDescriptor uses an unqualified type but catch clauses must
4279   // be at least as CV qualified.  Encode this requirement into the Flags
4280   // bitfield.
4281   uint32_t Flags = 0;
4282   if (IsConst)
4283     Flags |= 1;
4284   if (IsVolatile)
4285     Flags |= 2;
4286   if (IsUnaligned)
4287     Flags |= 4;
4288 
4289   // The cleanup-function (a destructor) must be called when the exception
4290   // object's lifetime ends.
4291   llvm::Constant *CleanupFn = llvm::Constant::getNullValue(CGM.Int8PtrTy);
4292   if (const CXXRecordDecl *RD = T->getAsCXXRecordDecl())
4293     if (CXXDestructorDecl *DtorD = RD->getDestructor())
4294       if (!DtorD->isTrivial())
4295         CleanupFn = llvm::ConstantExpr::getBitCast(
4296             CGM.getAddrOfCXXStructor(GlobalDecl(DtorD, Dtor_Complete)),
4297             CGM.Int8PtrTy);
4298   // This is unused as far as we can tell, initialize it to null.
4299   llvm::Constant *ForwardCompat =
4300       getImageRelativeConstant(llvm::Constant::getNullValue(CGM.Int8PtrTy));
4301   llvm::Constant *PointerToCatchableTypes = getImageRelativeConstant(
4302       llvm::ConstantExpr::getBitCast(CTA, CGM.Int8PtrTy));
4303   llvm::StructType *TIType = getThrowInfoType();
4304   llvm::Constant *Fields[] = {
4305       llvm::ConstantInt::get(CGM.IntTy, Flags), // Flags
4306       getImageRelativeConstant(CleanupFn),      // CleanupFn
4307       ForwardCompat,                            // ForwardCompat
4308       PointerToCatchableTypes                   // CatchableTypeArray
4309   };
4310   auto *GV = new llvm::GlobalVariable(
4311       CGM.getModule(), TIType, /*isConstant=*/true, getLinkageForRTTI(T),
4312       llvm::ConstantStruct::get(TIType, Fields), StringRef(MangledName));
4313   GV->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
4314   GV->setSection(".xdata");
4315   if (GV->isWeakForLinker())
4316     GV->setComdat(CGM.getModule().getOrInsertComdat(GV->getName()));
4317   return GV;
4318 }
4319 
4320 void MicrosoftCXXABI::emitThrow(CodeGenFunction &CGF, const CXXThrowExpr *E) {
4321   const Expr *SubExpr = E->getSubExpr();
4322   QualType ThrowType = SubExpr->getType();
4323   // The exception object lives on the stack and it's address is passed to the
4324   // runtime function.
4325   Address AI = CGF.CreateMemTemp(ThrowType);
4326   CGF.EmitAnyExprToMem(SubExpr, AI, ThrowType.getQualifiers(),
4327                        /*IsInit=*/true);
4328 
4329   // The so-called ThrowInfo is used to describe how the exception object may be
4330   // caught.
4331   llvm::GlobalVariable *TI = getThrowInfo(ThrowType);
4332 
4333   // Call into the runtime to throw the exception.
4334   llvm::Value *Args[] = {
4335     CGF.Builder.CreateBitCast(AI.getPointer(), CGM.Int8PtrTy),
4336     TI
4337   };
4338   CGF.EmitNoreturnRuntimeCallOrInvoke(getThrowFn(), Args);
4339 }
4340 
4341 std::pair<llvm::Value *, const CXXRecordDecl *>
4342 MicrosoftCXXABI::LoadVTablePtr(CodeGenFunction &CGF, Address This,
4343                                const CXXRecordDecl *RD) {
4344   std::tie(This, std::ignore, RD) =
4345       performBaseAdjustment(CGF, This, QualType(RD->getTypeForDecl(), 0));
4346   return {CGF.GetVTablePtr(This, CGM.Int8PtrTy, RD), RD};
4347 }
4348