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:
MicrosoftCXXABI(CodeGenModule & CGM)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 
isSRetParameterAfterThis() const59   bool isSRetParameterAfterThis() const override { return true; }
60 
isThisCompleteObject(GlobalDecl GD) const61   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 
getSrcArgforCopyCtor(const CXXConstructorDecl * CD,FunctionArgList & Args) const82   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 
getVBPtrOffsets(const CXXRecordDecl * RD)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 
GetPureVirtualCallName()113   StringRef GetPureVirtualCallName() override { return "_purecall"; }
GetDeletedVirtualCallName()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.
getCatchAllTypeInfo()133   CatchTypeInfo getCatchAllTypeInfo() override {
134     // For -EHa catch(...) must handle HW exception
135     // Adjective = HT_IsStdDotDot (0x40), only catch C++ exceptions
136     if (getContext().getLangOpts().EHAsynch)
137       return CatchTypeInfo{nullptr, 0};
138     else
139       return CatchTypeInfo{nullptr, 0x40};
140   }
141 
142   bool shouldTypeidBeNullChecked(bool IsDeref, QualType SrcRecordTy) override;
143   void EmitBadTypeidCall(CodeGenFunction &CGF) override;
144   llvm::Value *EmitTypeid(CodeGenFunction &CGF, QualType SrcRecordTy,
145                           Address ThisPtr,
146                           llvm::Type *StdTypeInfoPtrTy) override;
147 
148   bool shouldDynamicCastCallBeNullChecked(bool SrcIsPtr,
149                                           QualType SrcRecordTy) override;
150 
151   llvm::Value *EmitDynamicCastCall(CodeGenFunction &CGF, Address Value,
152                                    QualType SrcRecordTy, QualType DestTy,
153                                    QualType DestRecordTy,
154                                    llvm::BasicBlock *CastEnd) override;
155 
156   llvm::Value *EmitDynamicCastToVoid(CodeGenFunction &CGF, Address Value,
157                                      QualType SrcRecordTy,
158                                      QualType DestTy) override;
159 
160   bool EmitBadCastCall(CodeGenFunction &CGF) override;
canSpeculativelyEmitVTable(const CXXRecordDecl * RD) const161   bool canSpeculativelyEmitVTable(const CXXRecordDecl *RD) const override {
162     return false;
163   }
164 
165   llvm::Value *
166   GetVirtualBaseClassOffset(CodeGenFunction &CGF, Address This,
167                             const CXXRecordDecl *ClassDecl,
168                             const CXXRecordDecl *BaseClassDecl) override;
169 
170   llvm::BasicBlock *
171   EmitCtorCompleteObjectHandler(CodeGenFunction &CGF,
172                                 const CXXRecordDecl *RD) override;
173 
174   llvm::BasicBlock *
175   EmitDtorCompleteObjectHandler(CodeGenFunction &CGF);
176 
177   void initializeHiddenVirtualInheritanceMembers(CodeGenFunction &CGF,
178                                               const CXXRecordDecl *RD) override;
179 
180   void EmitCXXConstructors(const CXXConstructorDecl *D) override;
181 
182   // Background on MSVC destructors
183   // ==============================
184   //
185   // Both Itanium and MSVC ABIs have destructor variants.  The variant names
186   // roughly correspond in the following way:
187   //   Itanium       Microsoft
188   //   Base       -> no name, just ~Class
189   //   Complete   -> vbase destructor
190   //   Deleting   -> scalar deleting destructor
191   //                 vector deleting destructor
192   //
193   // The base and complete destructors are the same as in Itanium, although the
194   // complete destructor does not accept a VTT parameter when there are virtual
195   // bases.  A separate mechanism involving vtordisps is used to ensure that
196   // virtual methods of destroyed subobjects are not called.
197   //
198   // The deleting destructors accept an i32 bitfield as a second parameter.  Bit
199   // 1 indicates if the memory should be deleted.  Bit 2 indicates if the this
200   // pointer points to an array.  The scalar deleting destructor assumes that
201   // bit 2 is zero, and therefore does not contain a loop.
202   //
203   // For virtual destructors, only one entry is reserved in the vftable, and it
204   // always points to the vector deleting destructor.  The vector deleting
205   // destructor is the most general, so it can be used to destroy objects in
206   // place, delete single heap objects, or delete arrays.
207   //
208   // A TU defining a non-inline destructor is only guaranteed to emit a base
209   // destructor, and all of the other variants are emitted on an as-needed basis
210   // in COMDATs.  Because a non-base destructor can be emitted in a TU that
211   // lacks a definition for the destructor, non-base destructors must always
212   // delegate to or alias the base destructor.
213 
214   AddedStructorArgCounts
215   buildStructorSignature(GlobalDecl GD,
216                          SmallVectorImpl<CanQualType> &ArgTys) override;
217 
218   /// Non-base dtors should be emitted as delegating thunks in this ABI.
useThunkForDtorVariant(const CXXDestructorDecl * Dtor,CXXDtorType DT) const219   bool useThunkForDtorVariant(const CXXDestructorDecl *Dtor,
220                               CXXDtorType DT) const override {
221     return DT != Dtor_Base;
222   }
223 
224   void setCXXDestructorDLLStorage(llvm::GlobalValue *GV,
225                                   const CXXDestructorDecl *Dtor,
226                                   CXXDtorType DT) const override;
227 
228   llvm::GlobalValue::LinkageTypes
229   getCXXDestructorLinkage(GVALinkage Linkage, const CXXDestructorDecl *Dtor,
230                           CXXDtorType DT) const override;
231 
232   void EmitCXXDestructors(const CXXDestructorDecl *D) override;
233 
234   const CXXRecordDecl *
getThisArgumentTypeForMethod(const CXXMethodDecl * MD)235   getThisArgumentTypeForMethod(const CXXMethodDecl *MD) override {
236     if (MD->isVirtual() && !isa<CXXDestructorDecl>(MD)) {
237       MethodVFTableLocation ML =
238           CGM.getMicrosoftVTableContext().getMethodVFTableLocation(MD);
239       // The vbases might be ordered differently in the final overrider object
240       // and the complete object, so the "this" argument may sometimes point to
241       // memory that has no particular type (e.g. past the complete object).
242       // In this case, we just use a generic pointer type.
243       // FIXME: might want to have a more precise type in the non-virtual
244       // multiple inheritance case.
245       if (ML.VBase || !ML.VFPtrOffset.isZero())
246         return nullptr;
247     }
248     return MD->getParent();
249   }
250 
251   Address
252   adjustThisArgumentForVirtualFunctionCall(CodeGenFunction &CGF, GlobalDecl GD,
253                                            Address This,
254                                            bool VirtualCall) override;
255 
256   void addImplicitStructorParams(CodeGenFunction &CGF, QualType &ResTy,
257                                  FunctionArgList &Params) override;
258 
259   void EmitInstanceFunctionProlog(CodeGenFunction &CGF) override;
260 
261   AddedStructorArgs getImplicitConstructorArgs(CodeGenFunction &CGF,
262                                                const CXXConstructorDecl *D,
263                                                CXXCtorType Type,
264                                                bool ForVirtualBase,
265                                                bool Delegating) override;
266 
267   llvm::Value *getCXXDestructorImplicitParam(CodeGenFunction &CGF,
268                                              const CXXDestructorDecl *DD,
269                                              CXXDtorType Type,
270                                              bool ForVirtualBase,
271                                              bool Delegating) override;
272 
273   void EmitDestructorCall(CodeGenFunction &CGF, const CXXDestructorDecl *DD,
274                           CXXDtorType Type, bool ForVirtualBase,
275                           bool Delegating, Address This,
276                           QualType ThisTy) override;
277 
278   void emitVTableTypeMetadata(const VPtrInfo &Info, const CXXRecordDecl *RD,
279                               llvm::GlobalVariable *VTable);
280 
281   void emitVTableDefinitions(CodeGenVTables &CGVT,
282                              const CXXRecordDecl *RD) override;
283 
284   bool isVirtualOffsetNeededForVTableField(CodeGenFunction &CGF,
285                                            CodeGenFunction::VPtr Vptr) override;
286 
287   /// Don't initialize vptrs if dynamic class
288   /// is marked with with the 'novtable' attribute.
doStructorsInitializeVPtrs(const CXXRecordDecl * VTableClass)289   bool doStructorsInitializeVPtrs(const CXXRecordDecl *VTableClass) override {
290     return !VTableClass->hasAttr<MSNoVTableAttr>();
291   }
292 
293   llvm::Constant *
294   getVTableAddressPoint(BaseSubobject Base,
295                         const CXXRecordDecl *VTableClass) override;
296 
297   llvm::Value *getVTableAddressPointInStructor(
298       CodeGenFunction &CGF, const CXXRecordDecl *VTableClass,
299       BaseSubobject Base, const CXXRecordDecl *NearestVBase) override;
300 
301   llvm::Constant *
302   getVTableAddressPointForConstExpr(BaseSubobject Base,
303                                     const CXXRecordDecl *VTableClass) override;
304 
305   llvm::GlobalVariable *getAddrOfVTable(const CXXRecordDecl *RD,
306                                         CharUnits VPtrOffset) override;
307 
308   CGCallee getVirtualFunctionPointer(CodeGenFunction &CGF, GlobalDecl GD,
309                                      Address This, llvm::Type *Ty,
310                                      SourceLocation Loc) override;
311 
312   llvm::Value *EmitVirtualDestructorCall(CodeGenFunction &CGF,
313                                          const CXXDestructorDecl *Dtor,
314                                          CXXDtorType DtorType, Address This,
315                                          DeleteOrMemberCallExpr E) override;
316 
adjustCallArgsForDestructorThunk(CodeGenFunction & CGF,GlobalDecl GD,CallArgList & CallArgs)317   void adjustCallArgsForDestructorThunk(CodeGenFunction &CGF, GlobalDecl GD,
318                                         CallArgList &CallArgs) override {
319     assert(GD.getDtorType() == Dtor_Deleting &&
320            "Only deleting destructor thunks are available in this ABI");
321     CallArgs.add(RValue::get(getStructorImplicitParamValue(CGF)),
322                  getContext().IntTy);
323   }
324 
325   void emitVirtualInheritanceTables(const CXXRecordDecl *RD) override;
326 
327   llvm::GlobalVariable *
328   getAddrOfVBTable(const VPtrInfo &VBT, const CXXRecordDecl *RD,
329                    llvm::GlobalVariable::LinkageTypes Linkage);
330 
331   llvm::GlobalVariable *
getAddrOfVirtualDisplacementMap(const CXXRecordDecl * SrcRD,const CXXRecordDecl * DstRD)332   getAddrOfVirtualDisplacementMap(const CXXRecordDecl *SrcRD,
333                                   const CXXRecordDecl *DstRD) {
334     SmallString<256> OutName;
335     llvm::raw_svector_ostream Out(OutName);
336     getMangleContext().mangleCXXVirtualDisplacementMap(SrcRD, DstRD, Out);
337     StringRef MangledName = OutName.str();
338 
339     if (auto *VDispMap = CGM.getModule().getNamedGlobal(MangledName))
340       return VDispMap;
341 
342     MicrosoftVTableContext &VTContext = CGM.getMicrosoftVTableContext();
343     unsigned NumEntries = 1 + SrcRD->getNumVBases();
344     SmallVector<llvm::Constant *, 4> Map(NumEntries,
345                                          llvm::UndefValue::get(CGM.IntTy));
346     Map[0] = llvm::ConstantInt::get(CGM.IntTy, 0);
347     bool AnyDifferent = false;
348     for (const auto &I : SrcRD->vbases()) {
349       const CXXRecordDecl *VBase = I.getType()->getAsCXXRecordDecl();
350       if (!DstRD->isVirtuallyDerivedFrom(VBase))
351         continue;
352 
353       unsigned SrcVBIndex = VTContext.getVBTableIndex(SrcRD, VBase);
354       unsigned DstVBIndex = VTContext.getVBTableIndex(DstRD, VBase);
355       Map[SrcVBIndex] = llvm::ConstantInt::get(CGM.IntTy, DstVBIndex * 4);
356       AnyDifferent |= SrcVBIndex != DstVBIndex;
357     }
358     // This map would be useless, don't use it.
359     if (!AnyDifferent)
360       return nullptr;
361 
362     llvm::ArrayType *VDispMapTy = llvm::ArrayType::get(CGM.IntTy, Map.size());
363     llvm::Constant *Init = llvm::ConstantArray::get(VDispMapTy, Map);
364     llvm::GlobalValue::LinkageTypes Linkage =
365         SrcRD->isExternallyVisible() && DstRD->isExternallyVisible()
366             ? llvm::GlobalValue::LinkOnceODRLinkage
367             : llvm::GlobalValue::InternalLinkage;
368     auto *VDispMap = new llvm::GlobalVariable(
369         CGM.getModule(), VDispMapTy, /*isConstant=*/true, Linkage,
370         /*Initializer=*/Init, MangledName);
371     return VDispMap;
372   }
373 
374   void emitVBTableDefinition(const VPtrInfo &VBT, const CXXRecordDecl *RD,
375                              llvm::GlobalVariable *GV) const;
376 
setThunkLinkage(llvm::Function * Thunk,bool ForVTable,GlobalDecl GD,bool ReturnAdjustment)377   void setThunkLinkage(llvm::Function *Thunk, bool ForVTable,
378                        GlobalDecl GD, bool ReturnAdjustment) override {
379     GVALinkage Linkage =
380         getContext().GetGVALinkageForFunction(cast<FunctionDecl>(GD.getDecl()));
381 
382     if (Linkage == GVA_Internal)
383       Thunk->setLinkage(llvm::GlobalValue::InternalLinkage);
384     else if (ReturnAdjustment)
385       Thunk->setLinkage(llvm::GlobalValue::WeakODRLinkage);
386     else
387       Thunk->setLinkage(llvm::GlobalValue::LinkOnceODRLinkage);
388   }
389 
exportThunk()390   bool exportThunk() override { return false; }
391 
392   llvm::Value *performThisAdjustment(CodeGenFunction &CGF, Address This,
393                                      const ThisAdjustment &TA) override;
394 
395   llvm::Value *performReturnAdjustment(CodeGenFunction &CGF, Address Ret,
396                                        const ReturnAdjustment &RA) override;
397 
398   void EmitThreadLocalInitFuncs(
399       CodeGenModule &CGM, ArrayRef<const VarDecl *> CXXThreadLocals,
400       ArrayRef<llvm::Function *> CXXThreadLocalInits,
401       ArrayRef<const VarDecl *> CXXThreadLocalInitVars) override;
402 
usesThreadWrapperFunction(const VarDecl * VD) const403   bool usesThreadWrapperFunction(const VarDecl *VD) const override {
404     return false;
405   }
406   LValue EmitThreadLocalVarDeclLValue(CodeGenFunction &CGF, const VarDecl *VD,
407                                       QualType LValType) override;
408 
409   void EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D,
410                        llvm::GlobalVariable *DeclPtr,
411                        bool PerformInit) override;
412   void registerGlobalDtor(CodeGenFunction &CGF, const VarDecl &D,
413                           llvm::FunctionCallee Dtor,
414                           llvm::Constant *Addr) override;
415 
416   // ==== Notes on array cookies =========
417   //
418   // MSVC seems to only use cookies when the class has a destructor; a
419   // two-argument usual array deallocation function isn't sufficient.
420   //
421   // For example, this code prints "100" and "1":
422   //   struct A {
423   //     char x;
424   //     void *operator new[](size_t sz) {
425   //       printf("%u\n", sz);
426   //       return malloc(sz);
427   //     }
428   //     void operator delete[](void *p, size_t sz) {
429   //       printf("%u\n", sz);
430   //       free(p);
431   //     }
432   //   };
433   //   int main() {
434   //     A *p = new A[100];
435   //     delete[] p;
436   //   }
437   // Whereas it prints "104" and "104" if you give A a destructor.
438 
439   bool requiresArrayCookie(const CXXDeleteExpr *expr,
440                            QualType elementType) override;
441   bool requiresArrayCookie(const CXXNewExpr *expr) override;
442   CharUnits getArrayCookieSizeImpl(QualType type) override;
443   Address InitializeArrayCookie(CodeGenFunction &CGF,
444                                 Address NewPtr,
445                                 llvm::Value *NumElements,
446                                 const CXXNewExpr *expr,
447                                 QualType ElementType) override;
448   llvm::Value *readArrayCookieImpl(CodeGenFunction &CGF,
449                                    Address allocPtr,
450                                    CharUnits cookieSize) override;
451 
452   friend struct MSRTTIBuilder;
453 
isImageRelative() const454   bool isImageRelative() const {
455     return CGM.getTarget().getPointerWidth(/*AddrSpace=*/0) == 64;
456   }
457 
458   // 5 routines for constructing the llvm types for MS RTTI structs.
getTypeDescriptorType(StringRef TypeInfoString)459   llvm::StructType *getTypeDescriptorType(StringRef TypeInfoString) {
460     llvm::SmallString<32> TDTypeName("rtti.TypeDescriptor");
461     TDTypeName += llvm::utostr(TypeInfoString.size());
462     llvm::StructType *&TypeDescriptorType =
463         TypeDescriptorTypeMap[TypeInfoString.size()];
464     if (TypeDescriptorType)
465       return TypeDescriptorType;
466     llvm::Type *FieldTypes[] = {
467         CGM.Int8PtrPtrTy,
468         CGM.Int8PtrTy,
469         llvm::ArrayType::get(CGM.Int8Ty, TypeInfoString.size() + 1)};
470     TypeDescriptorType =
471         llvm::StructType::create(CGM.getLLVMContext(), FieldTypes, TDTypeName);
472     return TypeDescriptorType;
473   }
474 
getImageRelativeType(llvm::Type * PtrType)475   llvm::Type *getImageRelativeType(llvm::Type *PtrType) {
476     if (!isImageRelative())
477       return PtrType;
478     return CGM.IntTy;
479   }
480 
getBaseClassDescriptorType()481   llvm::StructType *getBaseClassDescriptorType() {
482     if (BaseClassDescriptorType)
483       return BaseClassDescriptorType;
484     llvm::Type *FieldTypes[] = {
485         getImageRelativeType(CGM.Int8PtrTy),
486         CGM.IntTy,
487         CGM.IntTy,
488         CGM.IntTy,
489         CGM.IntTy,
490         CGM.IntTy,
491         getImageRelativeType(getClassHierarchyDescriptorType()->getPointerTo()),
492     };
493     BaseClassDescriptorType = llvm::StructType::create(
494         CGM.getLLVMContext(), FieldTypes, "rtti.BaseClassDescriptor");
495     return BaseClassDescriptorType;
496   }
497 
getClassHierarchyDescriptorType()498   llvm::StructType *getClassHierarchyDescriptorType() {
499     if (ClassHierarchyDescriptorType)
500       return ClassHierarchyDescriptorType;
501     // Forward-declare RTTIClassHierarchyDescriptor to break a cycle.
502     ClassHierarchyDescriptorType = llvm::StructType::create(
503         CGM.getLLVMContext(), "rtti.ClassHierarchyDescriptor");
504     llvm::Type *FieldTypes[] = {
505         CGM.IntTy,
506         CGM.IntTy,
507         CGM.IntTy,
508         getImageRelativeType(
509             getBaseClassDescriptorType()->getPointerTo()->getPointerTo()),
510     };
511     ClassHierarchyDescriptorType->setBody(FieldTypes);
512     return ClassHierarchyDescriptorType;
513   }
514 
getCompleteObjectLocatorType()515   llvm::StructType *getCompleteObjectLocatorType() {
516     if (CompleteObjectLocatorType)
517       return CompleteObjectLocatorType;
518     CompleteObjectLocatorType = llvm::StructType::create(
519         CGM.getLLVMContext(), "rtti.CompleteObjectLocator");
520     llvm::Type *FieldTypes[] = {
521         CGM.IntTy,
522         CGM.IntTy,
523         CGM.IntTy,
524         getImageRelativeType(CGM.Int8PtrTy),
525         getImageRelativeType(getClassHierarchyDescriptorType()->getPointerTo()),
526         getImageRelativeType(CompleteObjectLocatorType),
527     };
528     llvm::ArrayRef<llvm::Type *> FieldTypesRef(FieldTypes);
529     if (!isImageRelative())
530       FieldTypesRef = FieldTypesRef.drop_back();
531     CompleteObjectLocatorType->setBody(FieldTypesRef);
532     return CompleteObjectLocatorType;
533   }
534 
getImageBase()535   llvm::GlobalVariable *getImageBase() {
536     StringRef Name = "__ImageBase";
537     if (llvm::GlobalVariable *GV = CGM.getModule().getNamedGlobal(Name))
538       return GV;
539 
540     auto *GV = new llvm::GlobalVariable(CGM.getModule(), CGM.Int8Ty,
541                                         /*isConstant=*/true,
542                                         llvm::GlobalValue::ExternalLinkage,
543                                         /*Initializer=*/nullptr, Name);
544     CGM.setDSOLocal(GV);
545     return GV;
546   }
547 
getImageRelativeConstant(llvm::Constant * PtrVal)548   llvm::Constant *getImageRelativeConstant(llvm::Constant *PtrVal) {
549     if (!isImageRelative())
550       return PtrVal;
551 
552     if (PtrVal->isNullValue())
553       return llvm::Constant::getNullValue(CGM.IntTy);
554 
555     llvm::Constant *ImageBaseAsInt =
556         llvm::ConstantExpr::getPtrToInt(getImageBase(), CGM.IntPtrTy);
557     llvm::Constant *PtrValAsInt =
558         llvm::ConstantExpr::getPtrToInt(PtrVal, CGM.IntPtrTy);
559     llvm::Constant *Diff =
560         llvm::ConstantExpr::getSub(PtrValAsInt, ImageBaseAsInt,
561                                    /*HasNUW=*/true, /*HasNSW=*/true);
562     return llvm::ConstantExpr::getTrunc(Diff, CGM.IntTy);
563   }
564 
565 private:
getMangleContext()566   MicrosoftMangleContext &getMangleContext() {
567     return cast<MicrosoftMangleContext>(CodeGen::CGCXXABI::getMangleContext());
568   }
569 
getZeroInt()570   llvm::Constant *getZeroInt() {
571     return llvm::ConstantInt::get(CGM.IntTy, 0);
572   }
573 
getAllOnesInt()574   llvm::Constant *getAllOnesInt() {
575     return  llvm::Constant::getAllOnesValue(CGM.IntTy);
576   }
577 
578   CharUnits getVirtualFunctionPrologueThisAdjustment(GlobalDecl GD) override;
579 
580   void
581   GetNullMemberPointerFields(const MemberPointerType *MPT,
582                              llvm::SmallVectorImpl<llvm::Constant *> &fields);
583 
584   /// Shared code for virtual base adjustment.  Returns the offset from
585   /// the vbptr to the virtual base.  Optionally returns the address of the
586   /// vbptr itself.
587   llvm::Value *GetVBaseOffsetFromVBPtr(CodeGenFunction &CGF,
588                                        Address Base,
589                                        llvm::Value *VBPtrOffset,
590                                        llvm::Value *VBTableOffset,
591                                        llvm::Value **VBPtr = nullptr);
592 
GetVBaseOffsetFromVBPtr(CodeGenFunction & CGF,Address Base,int32_t VBPtrOffset,int32_t VBTableOffset,llvm::Value ** VBPtr=nullptr)593   llvm::Value *GetVBaseOffsetFromVBPtr(CodeGenFunction &CGF,
594                                        Address Base,
595                                        int32_t VBPtrOffset,
596                                        int32_t VBTableOffset,
597                                        llvm::Value **VBPtr = nullptr) {
598     assert(VBTableOffset % 4 == 0 && "should be byte offset into table of i32s");
599     llvm::Value *VBPOffset = llvm::ConstantInt::get(CGM.IntTy, VBPtrOffset),
600                 *VBTOffset = llvm::ConstantInt::get(CGM.IntTy, VBTableOffset);
601     return GetVBaseOffsetFromVBPtr(CGF, Base, VBPOffset, VBTOffset, VBPtr);
602   }
603 
604   std::tuple<Address, llvm::Value *, const CXXRecordDecl *>
605   performBaseAdjustment(CodeGenFunction &CGF, Address Value,
606                         QualType SrcRecordTy);
607 
608   /// Performs a full virtual base adjustment.  Used to dereference
609   /// pointers to members of virtual bases.
610   llvm::Value *AdjustVirtualBase(CodeGenFunction &CGF, const Expr *E,
611                                  const CXXRecordDecl *RD, Address Base,
612                                  llvm::Value *VirtualBaseAdjustmentOffset,
613                                  llvm::Value *VBPtrOffset /* optional */);
614 
615   /// Emits a full member pointer with the fields common to data and
616   /// function member pointers.
617   llvm::Constant *EmitFullMemberPointer(llvm::Constant *FirstField,
618                                         bool IsMemberFunction,
619                                         const CXXRecordDecl *RD,
620                                         CharUnits NonVirtualBaseAdjustment,
621                                         unsigned VBTableIndex);
622 
623   bool MemberPointerConstantIsNull(const MemberPointerType *MPT,
624                                    llvm::Constant *MP);
625 
626   /// - Initialize all vbptrs of 'this' with RD as the complete type.
627   void EmitVBPtrStores(CodeGenFunction &CGF, const CXXRecordDecl *RD);
628 
629   /// Caching wrapper around VBTableBuilder::enumerateVBTables().
630   const VBTableGlobals &enumerateVBTables(const CXXRecordDecl *RD);
631 
632   /// Generate a thunk for calling a virtual member function MD.
633   llvm::Function *EmitVirtualMemPtrThunk(const CXXMethodDecl *MD,
634                                          const MethodVFTableLocation &ML);
635 
636   llvm::Constant *EmitMemberDataPointer(const CXXRecordDecl *RD,
637                                         CharUnits offset);
638 
639 public:
640   llvm::Type *ConvertMemberPointerType(const MemberPointerType *MPT) override;
641 
642   bool isZeroInitializable(const MemberPointerType *MPT) override;
643 
isMemberPointerConvertible(const MemberPointerType * MPT) const644   bool isMemberPointerConvertible(const MemberPointerType *MPT) const override {
645     const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();
646     return RD->hasAttr<MSInheritanceAttr>();
647   }
648 
649   llvm::Constant *EmitNullMemberPointer(const MemberPointerType *MPT) override;
650 
651   llvm::Constant *EmitMemberDataPointer(const MemberPointerType *MPT,
652                                         CharUnits offset) override;
653   llvm::Constant *EmitMemberFunctionPointer(const CXXMethodDecl *MD) override;
654   llvm::Constant *EmitMemberPointer(const APValue &MP, QualType MPT) override;
655 
656   llvm::Value *EmitMemberPointerComparison(CodeGenFunction &CGF,
657                                            llvm::Value *L,
658                                            llvm::Value *R,
659                                            const MemberPointerType *MPT,
660                                            bool Inequality) override;
661 
662   llvm::Value *EmitMemberPointerIsNotNull(CodeGenFunction &CGF,
663                                           llvm::Value *MemPtr,
664                                           const MemberPointerType *MPT) override;
665 
666   llvm::Value *
667   EmitMemberDataPointerAddress(CodeGenFunction &CGF, const Expr *E,
668                                Address Base, llvm::Value *MemPtr,
669                                const MemberPointerType *MPT) override;
670 
671   llvm::Value *EmitNonNullMemberPointerConversion(
672       const MemberPointerType *SrcTy, const MemberPointerType *DstTy,
673       CastKind CK, CastExpr::path_const_iterator PathBegin,
674       CastExpr::path_const_iterator PathEnd, llvm::Value *Src,
675       CGBuilderTy &Builder);
676 
677   llvm::Value *EmitMemberPointerConversion(CodeGenFunction &CGF,
678                                            const CastExpr *E,
679                                            llvm::Value *Src) override;
680 
681   llvm::Constant *EmitMemberPointerConversion(const CastExpr *E,
682                                               llvm::Constant *Src) override;
683 
684   llvm::Constant *EmitMemberPointerConversion(
685       const MemberPointerType *SrcTy, const MemberPointerType *DstTy,
686       CastKind CK, CastExpr::path_const_iterator PathBegin,
687       CastExpr::path_const_iterator PathEnd, llvm::Constant *Src);
688 
689   CGCallee
690   EmitLoadOfMemberFunctionPointer(CodeGenFunction &CGF, const Expr *E,
691                                   Address This, llvm::Value *&ThisPtrForCall,
692                                   llvm::Value *MemPtr,
693                                   const MemberPointerType *MPT) override;
694 
695   void emitCXXStructor(GlobalDecl GD) override;
696 
getCatchableTypeType()697   llvm::StructType *getCatchableTypeType() {
698     if (CatchableTypeType)
699       return CatchableTypeType;
700     llvm::Type *FieldTypes[] = {
701         CGM.IntTy,                           // Flags
702         getImageRelativeType(CGM.Int8PtrTy), // TypeDescriptor
703         CGM.IntTy,                           // NonVirtualAdjustment
704         CGM.IntTy,                           // OffsetToVBPtr
705         CGM.IntTy,                           // VBTableIndex
706         CGM.IntTy,                           // Size
707         getImageRelativeType(CGM.Int8PtrTy)  // CopyCtor
708     };
709     CatchableTypeType = llvm::StructType::create(
710         CGM.getLLVMContext(), FieldTypes, "eh.CatchableType");
711     return CatchableTypeType;
712   }
713 
getCatchableTypeArrayType(uint32_t NumEntries)714   llvm::StructType *getCatchableTypeArrayType(uint32_t NumEntries) {
715     llvm::StructType *&CatchableTypeArrayType =
716         CatchableTypeArrayTypeMap[NumEntries];
717     if (CatchableTypeArrayType)
718       return CatchableTypeArrayType;
719 
720     llvm::SmallString<23> CTATypeName("eh.CatchableTypeArray.");
721     CTATypeName += llvm::utostr(NumEntries);
722     llvm::Type *CTType =
723         getImageRelativeType(getCatchableTypeType()->getPointerTo());
724     llvm::Type *FieldTypes[] = {
725         CGM.IntTy,                               // NumEntries
726         llvm::ArrayType::get(CTType, NumEntries) // CatchableTypes
727     };
728     CatchableTypeArrayType =
729         llvm::StructType::create(CGM.getLLVMContext(), FieldTypes, CTATypeName);
730     return CatchableTypeArrayType;
731   }
732 
getThrowInfoType()733   llvm::StructType *getThrowInfoType() {
734     if (ThrowInfoType)
735       return ThrowInfoType;
736     llvm::Type *FieldTypes[] = {
737         CGM.IntTy,                           // Flags
738         getImageRelativeType(CGM.Int8PtrTy), // CleanupFn
739         getImageRelativeType(CGM.Int8PtrTy), // ForwardCompat
740         getImageRelativeType(CGM.Int8PtrTy)  // CatchableTypeArray
741     };
742     ThrowInfoType = llvm::StructType::create(CGM.getLLVMContext(), FieldTypes,
743                                              "eh.ThrowInfo");
744     return ThrowInfoType;
745   }
746 
getThrowFn()747   llvm::FunctionCallee getThrowFn() {
748     // _CxxThrowException is passed an exception object and a ThrowInfo object
749     // which describes the exception.
750     llvm::Type *Args[] = {CGM.Int8PtrTy, getThrowInfoType()->getPointerTo()};
751     llvm::FunctionType *FTy =
752         llvm::FunctionType::get(CGM.VoidTy, Args, /*isVarArg=*/false);
753     llvm::FunctionCallee Throw =
754         CGM.CreateRuntimeFunction(FTy, "_CxxThrowException");
755     // _CxxThrowException is stdcall on 32-bit x86 platforms.
756     if (CGM.getTarget().getTriple().getArch() == llvm::Triple::x86) {
757       if (auto *Fn = dyn_cast<llvm::Function>(Throw.getCallee()))
758         Fn->setCallingConv(llvm::CallingConv::X86_StdCall);
759     }
760     return Throw;
761   }
762 
763   llvm::Function *getAddrOfCXXCtorClosure(const CXXConstructorDecl *CD,
764                                           CXXCtorType CT);
765 
766   llvm::Constant *getCatchableType(QualType T,
767                                    uint32_t NVOffset = 0,
768                                    int32_t VBPtrOffset = -1,
769                                    uint32_t VBIndex = 0);
770 
771   llvm::GlobalVariable *getCatchableTypeArray(QualType T);
772 
773   llvm::GlobalVariable *getThrowInfo(QualType T) override;
774 
775   std::pair<llvm::Value *, const CXXRecordDecl *>
776   LoadVTablePtr(CodeGenFunction &CGF, Address This,
777                 const CXXRecordDecl *RD) override;
778 
779   virtual bool
780   isPermittedToBeHomogeneousAggregate(const CXXRecordDecl *RD) const override;
781 
782 private:
783   typedef std::pair<const CXXRecordDecl *, CharUnits> VFTableIdTy;
784   typedef llvm::DenseMap<VFTableIdTy, llvm::GlobalVariable *> VTablesMapTy;
785   typedef llvm::DenseMap<VFTableIdTy, llvm::GlobalValue *> VFTablesMapTy;
786   /// All the vftables that have been referenced.
787   VFTablesMapTy VFTablesMap;
788   VTablesMapTy VTablesMap;
789 
790   /// This set holds the record decls we've deferred vtable emission for.
791   llvm::SmallPtrSet<const CXXRecordDecl *, 4> DeferredVFTables;
792 
793 
794   /// All the vbtables which have been referenced.
795   llvm::DenseMap<const CXXRecordDecl *, VBTableGlobals> VBTablesMap;
796 
797   /// Info on the global variable used to guard initialization of static locals.
798   /// The BitIndex field is only used for externally invisible declarations.
799   struct GuardInfo {
GuardInfo__anona6ec54210111::MicrosoftCXXABI::GuardInfo800     GuardInfo() : Guard(nullptr), BitIndex(0) {}
801     llvm::GlobalVariable *Guard;
802     unsigned BitIndex;
803   };
804 
805   /// Map from DeclContext to the current guard variable.  We assume that the
806   /// AST is visited in source code order.
807   llvm::DenseMap<const DeclContext *, GuardInfo> GuardVariableMap;
808   llvm::DenseMap<const DeclContext *, GuardInfo> ThreadLocalGuardVariableMap;
809   llvm::DenseMap<const DeclContext *, unsigned> ThreadSafeGuardNumMap;
810 
811   llvm::DenseMap<size_t, llvm::StructType *> TypeDescriptorTypeMap;
812   llvm::StructType *BaseClassDescriptorType;
813   llvm::StructType *ClassHierarchyDescriptorType;
814   llvm::StructType *CompleteObjectLocatorType;
815 
816   llvm::DenseMap<QualType, llvm::GlobalVariable *> CatchableTypeArrays;
817 
818   llvm::StructType *CatchableTypeType;
819   llvm::DenseMap<uint32_t, llvm::StructType *> CatchableTypeArrayTypeMap;
820   llvm::StructType *ThrowInfoType;
821 };
822 
823 }
824 
825 CGCXXABI::RecordArgABI
getRecordArgABI(const CXXRecordDecl * RD) const826 MicrosoftCXXABI::getRecordArgABI(const CXXRecordDecl *RD) const {
827   // Use the default C calling convention rules for things that can be passed in
828   // registers, i.e. non-trivially copyable records or records marked with
829   // [[trivial_abi]].
830   if (RD->canPassInRegisters())
831     return RAA_Default;
832 
833   switch (CGM.getTarget().getTriple().getArch()) {
834   default:
835     // FIXME: Implement for other architectures.
836     return RAA_Indirect;
837 
838   case llvm::Triple::thumb:
839     // Pass things indirectly for now because it is simple.
840     // FIXME: This is incompatible with MSVC for arguments with a dtor and no
841     // copy ctor.
842     return RAA_Indirect;
843 
844   case llvm::Triple::x86: {
845     // If the argument has *required* alignment greater than four bytes, pass
846     // it indirectly. Prior to MSVC version 19.14, passing overaligned
847     // arguments was not supported and resulted in a compiler error. In 19.14
848     // and later versions, such arguments are now passed indirectly.
849     TypeInfo Info = getContext().getTypeInfo(RD->getTypeForDecl());
850     if (Info.AlignIsRequired && Info.Align > 4)
851       return RAA_Indirect;
852 
853     // If C++ prohibits us from making a copy, construct the arguments directly
854     // into argument memory.
855     return RAA_DirectInMemory;
856   }
857 
858   case llvm::Triple::x86_64:
859   case llvm::Triple::aarch64:
860     return RAA_Indirect;
861   }
862 
863   llvm_unreachable("invalid enum");
864 }
865 
emitVirtualObjectDelete(CodeGenFunction & CGF,const CXXDeleteExpr * DE,Address Ptr,QualType ElementType,const CXXDestructorDecl * Dtor)866 void MicrosoftCXXABI::emitVirtualObjectDelete(CodeGenFunction &CGF,
867                                               const CXXDeleteExpr *DE,
868                                               Address Ptr,
869                                               QualType ElementType,
870                                               const CXXDestructorDecl *Dtor) {
871   // FIXME: Provide a source location here even though there's no
872   // CXXMemberCallExpr for dtor call.
873   bool UseGlobalDelete = DE->isGlobalDelete();
874   CXXDtorType DtorType = UseGlobalDelete ? Dtor_Complete : Dtor_Deleting;
875   llvm::Value *MDThis = EmitVirtualDestructorCall(CGF, Dtor, DtorType, Ptr, DE);
876   if (UseGlobalDelete)
877     CGF.EmitDeleteCall(DE->getOperatorDelete(), MDThis, ElementType);
878 }
879 
emitRethrow(CodeGenFunction & CGF,bool isNoReturn)880 void MicrosoftCXXABI::emitRethrow(CodeGenFunction &CGF, bool isNoReturn) {
881   llvm::Value *Args[] = {
882       llvm::ConstantPointerNull::get(CGM.Int8PtrTy),
883       llvm::ConstantPointerNull::get(getThrowInfoType()->getPointerTo())};
884   llvm::FunctionCallee Fn = getThrowFn();
885   if (isNoReturn)
886     CGF.EmitNoreturnRuntimeCallOrInvoke(Fn, Args);
887   else
888     CGF.EmitRuntimeCallOrInvoke(Fn, Args);
889 }
890 
emitBeginCatch(CodeGenFunction & CGF,const CXXCatchStmt * S)891 void MicrosoftCXXABI::emitBeginCatch(CodeGenFunction &CGF,
892                                      const CXXCatchStmt *S) {
893   // In the MS ABI, the runtime handles the copy, and the catch handler is
894   // responsible for destruction.
895   VarDecl *CatchParam = S->getExceptionDecl();
896   llvm::BasicBlock *CatchPadBB = CGF.Builder.GetInsertBlock();
897   llvm::CatchPadInst *CPI =
898       cast<llvm::CatchPadInst>(CatchPadBB->getFirstNonPHI());
899   CGF.CurrentFuncletPad = CPI;
900 
901   // If this is a catch-all or the catch parameter is unnamed, we don't need to
902   // emit an alloca to the object.
903   if (!CatchParam || !CatchParam->getDeclName()) {
904     CGF.EHStack.pushCleanup<CatchRetScope>(NormalCleanup, CPI);
905     return;
906   }
907 
908   CodeGenFunction::AutoVarEmission var = CGF.EmitAutoVarAlloca(*CatchParam);
909   CPI->setArgOperand(2, var.getObjectAddress(CGF).getPointer());
910   CGF.EHStack.pushCleanup<CatchRetScope>(NormalCleanup, CPI);
911   CGF.EmitAutoVarCleanups(var);
912 }
913 
914 /// We need to perform a generic polymorphic operation (like a typeid
915 /// or a cast), which requires an object with a vfptr.  Adjust the
916 /// address to point to an object with a vfptr.
917 std::tuple<Address, llvm::Value *, const CXXRecordDecl *>
performBaseAdjustment(CodeGenFunction & CGF,Address Value,QualType SrcRecordTy)918 MicrosoftCXXABI::performBaseAdjustment(CodeGenFunction &CGF, Address Value,
919                                        QualType SrcRecordTy) {
920   Value = CGF.Builder.CreateBitCast(Value, CGF.Int8PtrTy);
921   const CXXRecordDecl *SrcDecl = SrcRecordTy->getAsCXXRecordDecl();
922   const ASTContext &Context = getContext();
923 
924   // If the class itself has a vfptr, great.  This check implicitly
925   // covers non-virtual base subobjects: a class with its own virtual
926   // functions would be a candidate to be a primary base.
927   if (Context.getASTRecordLayout(SrcDecl).hasExtendableVFPtr())
928     return std::make_tuple(Value, llvm::ConstantInt::get(CGF.Int32Ty, 0),
929                            SrcDecl);
930 
931   // Okay, one of the vbases must have a vfptr, or else this isn't
932   // actually a polymorphic class.
933   const CXXRecordDecl *PolymorphicBase = nullptr;
934   for (auto &Base : SrcDecl->vbases()) {
935     const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
936     if (Context.getASTRecordLayout(BaseDecl).hasExtendableVFPtr()) {
937       PolymorphicBase = BaseDecl;
938       break;
939     }
940   }
941   assert(PolymorphicBase && "polymorphic class has no apparent vfptr?");
942 
943   llvm::Value *Offset =
944     GetVirtualBaseClassOffset(CGF, Value, SrcDecl, PolymorphicBase);
945   llvm::Value *Ptr = CGF.Builder.CreateInBoundsGEP(
946       Value.getElementType(), Value.getPointer(), Offset);
947   CharUnits VBaseAlign =
948     CGF.CGM.getVBaseAlignment(Value.getAlignment(), SrcDecl, PolymorphicBase);
949   return std::make_tuple(Address(Ptr, VBaseAlign), Offset, PolymorphicBase);
950 }
951 
shouldTypeidBeNullChecked(bool IsDeref,QualType SrcRecordTy)952 bool MicrosoftCXXABI::shouldTypeidBeNullChecked(bool IsDeref,
953                                                 QualType SrcRecordTy) {
954   const CXXRecordDecl *SrcDecl = SrcRecordTy->getAsCXXRecordDecl();
955   return IsDeref &&
956          !getContext().getASTRecordLayout(SrcDecl).hasExtendableVFPtr();
957 }
958 
emitRTtypeidCall(CodeGenFunction & CGF,llvm::Value * Argument)959 static llvm::CallBase *emitRTtypeidCall(CodeGenFunction &CGF,
960                                         llvm::Value *Argument) {
961   llvm::Type *ArgTypes[] = {CGF.Int8PtrTy};
962   llvm::FunctionType *FTy =
963       llvm::FunctionType::get(CGF.Int8PtrTy, ArgTypes, false);
964   llvm::Value *Args[] = {Argument};
965   llvm::FunctionCallee Fn = CGF.CGM.CreateRuntimeFunction(FTy, "__RTtypeid");
966   return CGF.EmitRuntimeCallOrInvoke(Fn, Args);
967 }
968 
EmitBadTypeidCall(CodeGenFunction & CGF)969 void MicrosoftCXXABI::EmitBadTypeidCall(CodeGenFunction &CGF) {
970   llvm::CallBase *Call =
971       emitRTtypeidCall(CGF, llvm::Constant::getNullValue(CGM.VoidPtrTy));
972   Call->setDoesNotReturn();
973   CGF.Builder.CreateUnreachable();
974 }
975 
EmitTypeid(CodeGenFunction & CGF,QualType SrcRecordTy,Address ThisPtr,llvm::Type * StdTypeInfoPtrTy)976 llvm::Value *MicrosoftCXXABI::EmitTypeid(CodeGenFunction &CGF,
977                                          QualType SrcRecordTy,
978                                          Address ThisPtr,
979                                          llvm::Type *StdTypeInfoPtrTy) {
980   std::tie(ThisPtr, std::ignore, std::ignore) =
981       performBaseAdjustment(CGF, ThisPtr, SrcRecordTy);
982   llvm::CallBase *Typeid = emitRTtypeidCall(CGF, ThisPtr.getPointer());
983   return CGF.Builder.CreateBitCast(Typeid, StdTypeInfoPtrTy);
984 }
985 
shouldDynamicCastCallBeNullChecked(bool SrcIsPtr,QualType SrcRecordTy)986 bool MicrosoftCXXABI::shouldDynamicCastCallBeNullChecked(bool SrcIsPtr,
987                                                          QualType SrcRecordTy) {
988   const CXXRecordDecl *SrcDecl = SrcRecordTy->getAsCXXRecordDecl();
989   return SrcIsPtr &&
990          !getContext().getASTRecordLayout(SrcDecl).hasExtendableVFPtr();
991 }
992 
EmitDynamicCastCall(CodeGenFunction & CGF,Address This,QualType SrcRecordTy,QualType DestTy,QualType DestRecordTy,llvm::BasicBlock * CastEnd)993 llvm::Value *MicrosoftCXXABI::EmitDynamicCastCall(
994     CodeGenFunction &CGF, Address This, QualType SrcRecordTy,
995     QualType DestTy, QualType DestRecordTy, llvm::BasicBlock *CastEnd) {
996   llvm::Type *DestLTy = CGF.ConvertType(DestTy);
997 
998   llvm::Value *SrcRTTI =
999       CGF.CGM.GetAddrOfRTTIDescriptor(SrcRecordTy.getUnqualifiedType());
1000   llvm::Value *DestRTTI =
1001       CGF.CGM.GetAddrOfRTTIDescriptor(DestRecordTy.getUnqualifiedType());
1002 
1003   llvm::Value *Offset;
1004   std::tie(This, Offset, std::ignore) =
1005       performBaseAdjustment(CGF, This, SrcRecordTy);
1006   llvm::Value *ThisPtr = This.getPointer();
1007   Offset = CGF.Builder.CreateTrunc(Offset, CGF.Int32Ty);
1008 
1009   // PVOID __RTDynamicCast(
1010   //   PVOID inptr,
1011   //   LONG VfDelta,
1012   //   PVOID SrcType,
1013   //   PVOID TargetType,
1014   //   BOOL isReference)
1015   llvm::Type *ArgTypes[] = {CGF.Int8PtrTy, CGF.Int32Ty, CGF.Int8PtrTy,
1016                             CGF.Int8PtrTy, CGF.Int32Ty};
1017   llvm::FunctionCallee Function = CGF.CGM.CreateRuntimeFunction(
1018       llvm::FunctionType::get(CGF.Int8PtrTy, ArgTypes, false),
1019       "__RTDynamicCast");
1020   llvm::Value *Args[] = {
1021       ThisPtr, Offset, SrcRTTI, DestRTTI,
1022       llvm::ConstantInt::get(CGF.Int32Ty, DestTy->isReferenceType())};
1023   ThisPtr = CGF.EmitRuntimeCallOrInvoke(Function, Args);
1024   return CGF.Builder.CreateBitCast(ThisPtr, DestLTy);
1025 }
1026 
1027 llvm::Value *
EmitDynamicCastToVoid(CodeGenFunction & CGF,Address Value,QualType SrcRecordTy,QualType DestTy)1028 MicrosoftCXXABI::EmitDynamicCastToVoid(CodeGenFunction &CGF, Address Value,
1029                                        QualType SrcRecordTy,
1030                                        QualType DestTy) {
1031   std::tie(Value, std::ignore, std::ignore) =
1032       performBaseAdjustment(CGF, Value, SrcRecordTy);
1033 
1034   // PVOID __RTCastToVoid(
1035   //   PVOID inptr)
1036   llvm::Type *ArgTypes[] = {CGF.Int8PtrTy};
1037   llvm::FunctionCallee Function = CGF.CGM.CreateRuntimeFunction(
1038       llvm::FunctionType::get(CGF.Int8PtrTy, ArgTypes, false),
1039       "__RTCastToVoid");
1040   llvm::Value *Args[] = {Value.getPointer()};
1041   return CGF.EmitRuntimeCall(Function, Args);
1042 }
1043 
EmitBadCastCall(CodeGenFunction & CGF)1044 bool MicrosoftCXXABI::EmitBadCastCall(CodeGenFunction &CGF) {
1045   return false;
1046 }
1047 
GetVirtualBaseClassOffset(CodeGenFunction & CGF,Address This,const CXXRecordDecl * ClassDecl,const CXXRecordDecl * BaseClassDecl)1048 llvm::Value *MicrosoftCXXABI::GetVirtualBaseClassOffset(
1049     CodeGenFunction &CGF, Address This, const CXXRecordDecl *ClassDecl,
1050     const CXXRecordDecl *BaseClassDecl) {
1051   const ASTContext &Context = getContext();
1052   int64_t VBPtrChars =
1053       Context.getASTRecordLayout(ClassDecl).getVBPtrOffset().getQuantity();
1054   llvm::Value *VBPtrOffset = llvm::ConstantInt::get(CGM.PtrDiffTy, VBPtrChars);
1055   CharUnits IntSize = Context.getTypeSizeInChars(Context.IntTy);
1056   CharUnits VBTableChars =
1057       IntSize *
1058       CGM.getMicrosoftVTableContext().getVBTableIndex(ClassDecl, BaseClassDecl);
1059   llvm::Value *VBTableOffset =
1060       llvm::ConstantInt::get(CGM.IntTy, VBTableChars.getQuantity());
1061 
1062   llvm::Value *VBPtrToNewBase =
1063       GetVBaseOffsetFromVBPtr(CGF, This, VBPtrOffset, VBTableOffset);
1064   VBPtrToNewBase =
1065       CGF.Builder.CreateSExtOrBitCast(VBPtrToNewBase, CGM.PtrDiffTy);
1066   return CGF.Builder.CreateNSWAdd(VBPtrOffset, VBPtrToNewBase);
1067 }
1068 
HasThisReturn(GlobalDecl GD) const1069 bool MicrosoftCXXABI::HasThisReturn(GlobalDecl GD) const {
1070   return isa<CXXConstructorDecl>(GD.getDecl());
1071 }
1072 
isDeletingDtor(GlobalDecl GD)1073 static bool isDeletingDtor(GlobalDecl GD) {
1074   return isa<CXXDestructorDecl>(GD.getDecl()) &&
1075          GD.getDtorType() == Dtor_Deleting;
1076 }
1077 
hasMostDerivedReturn(GlobalDecl GD) const1078 bool MicrosoftCXXABI::hasMostDerivedReturn(GlobalDecl GD) const {
1079   return isDeletingDtor(GD);
1080 }
1081 
isTrivialForAArch64MSVC(const CXXRecordDecl * RD)1082 static bool isTrivialForAArch64MSVC(const CXXRecordDecl *RD) {
1083   // For AArch64, we use the C++14 definition of an aggregate, so we also
1084   // check for:
1085   //   No private or protected non static data members.
1086   //   No base classes
1087   //   No virtual functions
1088   // Additionally, we need to ensure that there is a trivial copy assignment
1089   // operator, a trivial destructor and no user-provided constructors.
1090   if (RD->hasProtectedFields() || RD->hasPrivateFields())
1091     return false;
1092   if (RD->getNumBases() > 0)
1093     return false;
1094   if (RD->isPolymorphic())
1095     return false;
1096   if (RD->hasNonTrivialCopyAssignment())
1097     return false;
1098   for (const CXXConstructorDecl *Ctor : RD->ctors())
1099     if (Ctor->isUserProvided())
1100       return false;
1101   if (RD->hasNonTrivialDestructor())
1102     return false;
1103   return true;
1104 }
1105 
classifyReturnType(CGFunctionInfo & FI) const1106 bool MicrosoftCXXABI::classifyReturnType(CGFunctionInfo &FI) const {
1107   const CXXRecordDecl *RD = FI.getReturnType()->getAsCXXRecordDecl();
1108   if (!RD)
1109     return false;
1110 
1111   // Normally, the C++ concept of "is trivially copyable" is used to determine
1112   // if a struct can be returned directly. However, as MSVC and the language
1113   // have evolved, the definition of "trivially copyable" has changed, while the
1114   // ABI must remain stable. AArch64 uses the C++14 concept of an "aggregate",
1115   // while other ISAs use the older concept of "plain old data".
1116   bool isTrivialForABI = RD->isPOD();
1117   bool isAArch64 = CGM.getTarget().getTriple().isAArch64();
1118   if (isAArch64)
1119     isTrivialForABI = RD->canPassInRegisters() && isTrivialForAArch64MSVC(RD);
1120 
1121   // MSVC always returns structs indirectly from C++ instance methods.
1122   bool isIndirectReturn = !isTrivialForABI || FI.isInstanceMethod();
1123 
1124   if (isIndirectReturn) {
1125     CharUnits Align = CGM.getContext().getTypeAlignInChars(FI.getReturnType());
1126     FI.getReturnInfo() = ABIArgInfo::getIndirect(Align, /*ByVal=*/false);
1127 
1128     // MSVC always passes `this` before the `sret` parameter.
1129     FI.getReturnInfo().setSRetAfterThis(FI.isInstanceMethod());
1130 
1131     // On AArch64, use the `inreg` attribute if the object is considered to not
1132     // be trivially copyable, or if this is an instance method struct return.
1133     FI.getReturnInfo().setInReg(isAArch64);
1134 
1135     return true;
1136   }
1137 
1138   // Otherwise, use the C ABI rules.
1139   return false;
1140 }
1141 
1142 llvm::BasicBlock *
EmitCtorCompleteObjectHandler(CodeGenFunction & CGF,const CXXRecordDecl * RD)1143 MicrosoftCXXABI::EmitCtorCompleteObjectHandler(CodeGenFunction &CGF,
1144                                                const CXXRecordDecl *RD) {
1145   llvm::Value *IsMostDerivedClass = getStructorImplicitParamValue(CGF);
1146   assert(IsMostDerivedClass &&
1147          "ctor for a class with virtual bases must have an implicit parameter");
1148   llvm::Value *IsCompleteObject =
1149     CGF.Builder.CreateIsNotNull(IsMostDerivedClass, "is_complete_object");
1150 
1151   llvm::BasicBlock *CallVbaseCtorsBB = CGF.createBasicBlock("ctor.init_vbases");
1152   llvm::BasicBlock *SkipVbaseCtorsBB = CGF.createBasicBlock("ctor.skip_vbases");
1153   CGF.Builder.CreateCondBr(IsCompleteObject,
1154                            CallVbaseCtorsBB, SkipVbaseCtorsBB);
1155 
1156   CGF.EmitBlock(CallVbaseCtorsBB);
1157 
1158   // Fill in the vbtable pointers here.
1159   EmitVBPtrStores(CGF, RD);
1160 
1161   // CGF will put the base ctor calls in this basic block for us later.
1162 
1163   return SkipVbaseCtorsBB;
1164 }
1165 
1166 llvm::BasicBlock *
EmitDtorCompleteObjectHandler(CodeGenFunction & CGF)1167 MicrosoftCXXABI::EmitDtorCompleteObjectHandler(CodeGenFunction &CGF) {
1168   llvm::Value *IsMostDerivedClass = getStructorImplicitParamValue(CGF);
1169   assert(IsMostDerivedClass &&
1170          "ctor for a class with virtual bases must have an implicit parameter");
1171   llvm::Value *IsCompleteObject =
1172       CGF.Builder.CreateIsNotNull(IsMostDerivedClass, "is_complete_object");
1173 
1174   llvm::BasicBlock *CallVbaseDtorsBB = CGF.createBasicBlock("Dtor.dtor_vbases");
1175   llvm::BasicBlock *SkipVbaseDtorsBB = CGF.createBasicBlock("Dtor.skip_vbases");
1176   CGF.Builder.CreateCondBr(IsCompleteObject,
1177                            CallVbaseDtorsBB, SkipVbaseDtorsBB);
1178 
1179   CGF.EmitBlock(CallVbaseDtorsBB);
1180   // CGF will put the base dtor calls in this basic block for us later.
1181 
1182   return SkipVbaseDtorsBB;
1183 }
1184 
initializeHiddenVirtualInheritanceMembers(CodeGenFunction & CGF,const CXXRecordDecl * RD)1185 void MicrosoftCXXABI::initializeHiddenVirtualInheritanceMembers(
1186     CodeGenFunction &CGF, const CXXRecordDecl *RD) {
1187   // In most cases, an override for a vbase virtual method can adjust
1188   // the "this" parameter by applying a constant offset.
1189   // However, this is not enough while a constructor or a destructor of some
1190   // class X is being executed if all the following conditions are met:
1191   //  - X has virtual bases, (1)
1192   //  - X overrides a virtual method M of a vbase Y, (2)
1193   //  - X itself is a vbase of the most derived class.
1194   //
1195   // If (1) and (2) are true, the vtorDisp for vbase Y is a hidden member of X
1196   // which holds the extra amount of "this" adjustment we must do when we use
1197   // the X vftables (i.e. during X ctor or dtor).
1198   // Outside the ctors and dtors, the values of vtorDisps are zero.
1199 
1200   const ASTRecordLayout &Layout = getContext().getASTRecordLayout(RD);
1201   typedef ASTRecordLayout::VBaseOffsetsMapTy VBOffsets;
1202   const VBOffsets &VBaseMap = Layout.getVBaseOffsetsMap();
1203   CGBuilderTy &Builder = CGF.Builder;
1204 
1205   unsigned AS = getThisAddress(CGF).getAddressSpace();
1206   llvm::Value *Int8This = nullptr;  // Initialize lazily.
1207 
1208   for (const CXXBaseSpecifier &S : RD->vbases()) {
1209     const CXXRecordDecl *VBase = S.getType()->getAsCXXRecordDecl();
1210     auto I = VBaseMap.find(VBase);
1211     assert(I != VBaseMap.end());
1212     if (!I->second.hasVtorDisp())
1213       continue;
1214 
1215     llvm::Value *VBaseOffset =
1216         GetVirtualBaseClassOffset(CGF, getThisAddress(CGF), RD, VBase);
1217     uint64_t ConstantVBaseOffset = I->second.VBaseOffset.getQuantity();
1218 
1219     // vtorDisp_for_vbase = vbptr[vbase_idx] - offsetof(RD, vbase).
1220     llvm::Value *VtorDispValue = Builder.CreateSub(
1221         VBaseOffset, llvm::ConstantInt::get(CGM.PtrDiffTy, ConstantVBaseOffset),
1222         "vtordisp.value");
1223     VtorDispValue = Builder.CreateTruncOrBitCast(VtorDispValue, CGF.Int32Ty);
1224 
1225     if (!Int8This)
1226       Int8This = Builder.CreateBitCast(getThisValue(CGF),
1227                                        CGF.Int8Ty->getPointerTo(AS));
1228     llvm::Value *VtorDispPtr =
1229         Builder.CreateInBoundsGEP(CGF.Int8Ty, Int8This, VBaseOffset);
1230     // vtorDisp is always the 32-bits before the vbase in the class layout.
1231     VtorDispPtr = Builder.CreateConstGEP1_32(CGF.Int8Ty, VtorDispPtr, -4);
1232     VtorDispPtr = Builder.CreateBitCast(
1233         VtorDispPtr, CGF.Int32Ty->getPointerTo(AS), "vtordisp.ptr");
1234 
1235     Builder.CreateAlignedStore(VtorDispValue, VtorDispPtr,
1236                                CharUnits::fromQuantity(4));
1237   }
1238 }
1239 
hasDefaultCXXMethodCC(ASTContext & Context,const CXXMethodDecl * MD)1240 static bool hasDefaultCXXMethodCC(ASTContext &Context,
1241                                   const CXXMethodDecl *MD) {
1242   CallingConv ExpectedCallingConv = Context.getDefaultCallingConvention(
1243       /*IsVariadic=*/false, /*IsCXXMethod=*/true);
1244   CallingConv ActualCallingConv =
1245       MD->getType()->castAs<FunctionProtoType>()->getCallConv();
1246   return ExpectedCallingConv == ActualCallingConv;
1247 }
1248 
EmitCXXConstructors(const CXXConstructorDecl * D)1249 void MicrosoftCXXABI::EmitCXXConstructors(const CXXConstructorDecl *D) {
1250   // There's only one constructor type in this ABI.
1251   CGM.EmitGlobal(GlobalDecl(D, Ctor_Complete));
1252 
1253   // Exported default constructors either have a simple call-site where they use
1254   // the typical calling convention and have a single 'this' pointer for an
1255   // argument -or- they get a wrapper function which appropriately thunks to the
1256   // real default constructor.  This thunk is the default constructor closure.
1257   if (D->hasAttr<DLLExportAttr>() && D->isDefaultConstructor() &&
1258       D->isDefined()) {
1259     if (!hasDefaultCXXMethodCC(getContext(), D) || D->getNumParams() != 0) {
1260       llvm::Function *Fn = getAddrOfCXXCtorClosure(D, Ctor_DefaultClosure);
1261       Fn->setLinkage(llvm::GlobalValue::WeakODRLinkage);
1262       CGM.setGVProperties(Fn, D);
1263     }
1264   }
1265 }
1266 
EmitVBPtrStores(CodeGenFunction & CGF,const CXXRecordDecl * RD)1267 void MicrosoftCXXABI::EmitVBPtrStores(CodeGenFunction &CGF,
1268                                       const CXXRecordDecl *RD) {
1269   Address This = getThisAddress(CGF);
1270   This = CGF.Builder.CreateElementBitCast(This, CGM.Int8Ty, "this.int8");
1271   const ASTContext &Context = getContext();
1272   const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
1273 
1274   const VBTableGlobals &VBGlobals = enumerateVBTables(RD);
1275   for (unsigned I = 0, E = VBGlobals.VBTables->size(); I != E; ++I) {
1276     const std::unique_ptr<VPtrInfo> &VBT = (*VBGlobals.VBTables)[I];
1277     llvm::GlobalVariable *GV = VBGlobals.Globals[I];
1278     const ASTRecordLayout &SubobjectLayout =
1279         Context.getASTRecordLayout(VBT->IntroducingObject);
1280     CharUnits Offs = VBT->NonVirtualOffset;
1281     Offs += SubobjectLayout.getVBPtrOffset();
1282     if (VBT->getVBaseWithVPtr())
1283       Offs += Layout.getVBaseClassOffset(VBT->getVBaseWithVPtr());
1284     Address VBPtr = CGF.Builder.CreateConstInBoundsByteGEP(This, Offs);
1285     llvm::Value *GVPtr =
1286         CGF.Builder.CreateConstInBoundsGEP2_32(GV->getValueType(), GV, 0, 0);
1287     VBPtr = CGF.Builder.CreateElementBitCast(VBPtr, GVPtr->getType(),
1288                                       "vbptr." + VBT->ObjectWithVPtr->getName());
1289     CGF.Builder.CreateStore(GVPtr, VBPtr);
1290   }
1291 }
1292 
1293 CGCXXABI::AddedStructorArgCounts
buildStructorSignature(GlobalDecl GD,SmallVectorImpl<CanQualType> & ArgTys)1294 MicrosoftCXXABI::buildStructorSignature(GlobalDecl GD,
1295                                         SmallVectorImpl<CanQualType> &ArgTys) {
1296   AddedStructorArgCounts Added;
1297   // TODO: 'for base' flag
1298   if (isa<CXXDestructorDecl>(GD.getDecl()) &&
1299       GD.getDtorType() == Dtor_Deleting) {
1300     // The scalar deleting destructor takes an implicit int parameter.
1301     ArgTys.push_back(getContext().IntTy);
1302     ++Added.Suffix;
1303   }
1304   auto *CD = dyn_cast<CXXConstructorDecl>(GD.getDecl());
1305   if (!CD)
1306     return Added;
1307 
1308   // All parameters are already in place except is_most_derived, which goes
1309   // after 'this' if it's variadic and last if it's not.
1310 
1311   const CXXRecordDecl *Class = CD->getParent();
1312   const FunctionProtoType *FPT = CD->getType()->castAs<FunctionProtoType>();
1313   if (Class->getNumVBases()) {
1314     if (FPT->isVariadic()) {
1315       ArgTys.insert(ArgTys.begin() + 1, getContext().IntTy);
1316       ++Added.Prefix;
1317     } else {
1318       ArgTys.push_back(getContext().IntTy);
1319       ++Added.Suffix;
1320     }
1321   }
1322 
1323   return Added;
1324 }
1325 
setCXXDestructorDLLStorage(llvm::GlobalValue * GV,const CXXDestructorDecl * Dtor,CXXDtorType DT) const1326 void MicrosoftCXXABI::setCXXDestructorDLLStorage(llvm::GlobalValue *GV,
1327                                                  const CXXDestructorDecl *Dtor,
1328                                                  CXXDtorType DT) const {
1329   // Deleting destructor variants are never imported or exported. Give them the
1330   // default storage class.
1331   if (DT == Dtor_Deleting) {
1332     GV->setDLLStorageClass(llvm::GlobalValue::DefaultStorageClass);
1333   } else {
1334     const NamedDecl *ND = Dtor;
1335     CGM.setDLLImportDLLExport(GV, ND);
1336   }
1337 }
1338 
getCXXDestructorLinkage(GVALinkage Linkage,const CXXDestructorDecl * Dtor,CXXDtorType DT) const1339 llvm::GlobalValue::LinkageTypes MicrosoftCXXABI::getCXXDestructorLinkage(
1340     GVALinkage Linkage, const CXXDestructorDecl *Dtor, CXXDtorType DT) const {
1341   // Internal things are always internal, regardless of attributes. After this,
1342   // we know the thunk is externally visible.
1343   if (Linkage == GVA_Internal)
1344     return llvm::GlobalValue::InternalLinkage;
1345 
1346   switch (DT) {
1347   case Dtor_Base:
1348     // The base destructor most closely tracks the user-declared constructor, so
1349     // we delegate back to the normal declarator case.
1350     return CGM.getLLVMLinkageForDeclarator(Dtor, Linkage,
1351                                            /*IsConstantVariable=*/false);
1352   case Dtor_Complete:
1353     // The complete destructor is like an inline function, but it may be
1354     // imported and therefore must be exported as well. This requires changing
1355     // the linkage if a DLL attribute is present.
1356     if (Dtor->hasAttr<DLLExportAttr>())
1357       return llvm::GlobalValue::WeakODRLinkage;
1358     if (Dtor->hasAttr<DLLImportAttr>())
1359       return llvm::GlobalValue::AvailableExternallyLinkage;
1360     return llvm::GlobalValue::LinkOnceODRLinkage;
1361   case Dtor_Deleting:
1362     // Deleting destructors are like inline functions. They have vague linkage
1363     // and are emitted everywhere they are used. They are internal if the class
1364     // is internal.
1365     return llvm::GlobalValue::LinkOnceODRLinkage;
1366   case Dtor_Comdat:
1367     llvm_unreachable("MS C++ ABI does not support comdat dtors");
1368   }
1369   llvm_unreachable("invalid dtor type");
1370 }
1371 
EmitCXXDestructors(const CXXDestructorDecl * D)1372 void MicrosoftCXXABI::EmitCXXDestructors(const CXXDestructorDecl *D) {
1373   // The TU defining a dtor is only guaranteed to emit a base destructor.  All
1374   // other destructor variants are delegating thunks.
1375   CGM.EmitGlobal(GlobalDecl(D, Dtor_Base));
1376 
1377   // If the class is dllexported, emit the complete (vbase) destructor wherever
1378   // the base dtor is emitted.
1379   // FIXME: To match MSVC, this should only be done when the class is exported
1380   // with -fdllexport-inlines enabled.
1381   if (D->getParent()->getNumVBases() > 0 && D->hasAttr<DLLExportAttr>())
1382     CGM.EmitGlobal(GlobalDecl(D, Dtor_Complete));
1383 }
1384 
1385 CharUnits
getVirtualFunctionPrologueThisAdjustment(GlobalDecl GD)1386 MicrosoftCXXABI::getVirtualFunctionPrologueThisAdjustment(GlobalDecl GD) {
1387   const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
1388 
1389   if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
1390     // Complete destructors take a pointer to the complete object as a
1391     // parameter, thus don't need this adjustment.
1392     if (GD.getDtorType() == Dtor_Complete)
1393       return CharUnits();
1394 
1395     // There's no Dtor_Base in vftable but it shares the this adjustment with
1396     // the deleting one, so look it up instead.
1397     GD = GlobalDecl(DD, Dtor_Deleting);
1398   }
1399 
1400   MethodVFTableLocation ML =
1401       CGM.getMicrosoftVTableContext().getMethodVFTableLocation(GD);
1402   CharUnits Adjustment = ML.VFPtrOffset;
1403 
1404   // Normal virtual instance methods need to adjust from the vfptr that first
1405   // defined the virtual method to the virtual base subobject, but destructors
1406   // do not.  The vector deleting destructor thunk applies this adjustment for
1407   // us if necessary.
1408   if (isa<CXXDestructorDecl>(MD))
1409     Adjustment = CharUnits::Zero();
1410 
1411   if (ML.VBase) {
1412     const ASTRecordLayout &DerivedLayout =
1413         getContext().getASTRecordLayout(MD->getParent());
1414     Adjustment += DerivedLayout.getVBaseClassOffset(ML.VBase);
1415   }
1416 
1417   return Adjustment;
1418 }
1419 
adjustThisArgumentForVirtualFunctionCall(CodeGenFunction & CGF,GlobalDecl GD,Address This,bool VirtualCall)1420 Address MicrosoftCXXABI::adjustThisArgumentForVirtualFunctionCall(
1421     CodeGenFunction &CGF, GlobalDecl GD, Address This,
1422     bool VirtualCall) {
1423   if (!VirtualCall) {
1424     // If the call of a virtual function is not virtual, we just have to
1425     // compensate for the adjustment the virtual function does in its prologue.
1426     CharUnits Adjustment = getVirtualFunctionPrologueThisAdjustment(GD);
1427     if (Adjustment.isZero())
1428       return This;
1429 
1430     This = CGF.Builder.CreateElementBitCast(This, CGF.Int8Ty);
1431     assert(Adjustment.isPositive());
1432     return CGF.Builder.CreateConstByteGEP(This, Adjustment);
1433   }
1434 
1435   const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
1436 
1437   GlobalDecl LookupGD = GD;
1438   if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
1439     // Complete dtors take a pointer to the complete object,
1440     // thus don't need adjustment.
1441     if (GD.getDtorType() == Dtor_Complete)
1442       return This;
1443 
1444     // There's only Dtor_Deleting in vftable but it shares the this adjustment
1445     // with the base one, so look up the deleting one instead.
1446     LookupGD = GlobalDecl(DD, Dtor_Deleting);
1447   }
1448   MethodVFTableLocation ML =
1449       CGM.getMicrosoftVTableContext().getMethodVFTableLocation(LookupGD);
1450 
1451   CharUnits StaticOffset = ML.VFPtrOffset;
1452 
1453   // Base destructors expect 'this' to point to the beginning of the base
1454   // subobject, not the first vfptr that happens to contain the virtual dtor.
1455   // However, we still need to apply the virtual base adjustment.
1456   if (isa<CXXDestructorDecl>(MD) && GD.getDtorType() == Dtor_Base)
1457     StaticOffset = CharUnits::Zero();
1458 
1459   Address Result = This;
1460   if (ML.VBase) {
1461     Result = CGF.Builder.CreateElementBitCast(Result, CGF.Int8Ty);
1462 
1463     const CXXRecordDecl *Derived = MD->getParent();
1464     const CXXRecordDecl *VBase = ML.VBase;
1465     llvm::Value *VBaseOffset =
1466       GetVirtualBaseClassOffset(CGF, Result, Derived, VBase);
1467     llvm::Value *VBasePtr = CGF.Builder.CreateInBoundsGEP(
1468         Result.getElementType(), Result.getPointer(), VBaseOffset);
1469     CharUnits VBaseAlign =
1470       CGF.CGM.getVBaseAlignment(Result.getAlignment(), Derived, VBase);
1471     Result = Address(VBasePtr, VBaseAlign);
1472   }
1473   if (!StaticOffset.isZero()) {
1474     assert(StaticOffset.isPositive());
1475     Result = CGF.Builder.CreateElementBitCast(Result, CGF.Int8Ty);
1476     if (ML.VBase) {
1477       // Non-virtual adjustment might result in a pointer outside the allocated
1478       // object, e.g. if the final overrider class is laid out after the virtual
1479       // base that declares a method in the most derived class.
1480       // FIXME: Update the code that emits this adjustment in thunks prologues.
1481       Result = CGF.Builder.CreateConstByteGEP(Result, StaticOffset);
1482     } else {
1483       Result = CGF.Builder.CreateConstInBoundsByteGEP(Result, StaticOffset);
1484     }
1485   }
1486   return Result;
1487 }
1488 
addImplicitStructorParams(CodeGenFunction & CGF,QualType & ResTy,FunctionArgList & Params)1489 void MicrosoftCXXABI::addImplicitStructorParams(CodeGenFunction &CGF,
1490                                                 QualType &ResTy,
1491                                                 FunctionArgList &Params) {
1492   ASTContext &Context = getContext();
1493   const CXXMethodDecl *MD = cast<CXXMethodDecl>(CGF.CurGD.getDecl());
1494   assert(isa<CXXConstructorDecl>(MD) || isa<CXXDestructorDecl>(MD));
1495   if (isa<CXXConstructorDecl>(MD) && MD->getParent()->getNumVBases()) {
1496     auto *IsMostDerived = ImplicitParamDecl::Create(
1497         Context, /*DC=*/nullptr, CGF.CurGD.getDecl()->getLocation(),
1498         &Context.Idents.get("is_most_derived"), Context.IntTy,
1499         ImplicitParamDecl::Other);
1500     // The 'most_derived' parameter goes second if the ctor is variadic and last
1501     // if it's not.  Dtors can't be variadic.
1502     const FunctionProtoType *FPT = MD->getType()->castAs<FunctionProtoType>();
1503     if (FPT->isVariadic())
1504       Params.insert(Params.begin() + 1, IsMostDerived);
1505     else
1506       Params.push_back(IsMostDerived);
1507     getStructorImplicitParamDecl(CGF) = IsMostDerived;
1508   } else if (isDeletingDtor(CGF.CurGD)) {
1509     auto *ShouldDelete = ImplicitParamDecl::Create(
1510         Context, /*DC=*/nullptr, CGF.CurGD.getDecl()->getLocation(),
1511         &Context.Idents.get("should_call_delete"), Context.IntTy,
1512         ImplicitParamDecl::Other);
1513     Params.push_back(ShouldDelete);
1514     getStructorImplicitParamDecl(CGF) = ShouldDelete;
1515   }
1516 }
1517 
EmitInstanceFunctionProlog(CodeGenFunction & CGF)1518 void MicrosoftCXXABI::EmitInstanceFunctionProlog(CodeGenFunction &CGF) {
1519   // Naked functions have no prolog.
1520   if (CGF.CurFuncDecl && CGF.CurFuncDecl->hasAttr<NakedAttr>())
1521     return;
1522 
1523   // Overridden virtual methods of non-primary bases need to adjust the incoming
1524   // 'this' pointer in the prologue. In this hierarchy, C::b will subtract
1525   // sizeof(void*) to adjust from B* to C*:
1526   //   struct A { virtual void a(); };
1527   //   struct B { virtual void b(); };
1528   //   struct C : A, B { virtual void b(); };
1529   //
1530   // Leave the value stored in the 'this' alloca unadjusted, so that the
1531   // debugger sees the unadjusted value. Microsoft debuggers require this, and
1532   // will apply the ThisAdjustment in the method type information.
1533   // FIXME: Do something better for DWARF debuggers, which won't expect this,
1534   // without making our codegen depend on debug info settings.
1535   llvm::Value *This = loadIncomingCXXThis(CGF);
1536   const CXXMethodDecl *MD = cast<CXXMethodDecl>(CGF.CurGD.getDecl());
1537   if (!CGF.CurFuncIsThunk && MD->isVirtual()) {
1538     CharUnits Adjustment = getVirtualFunctionPrologueThisAdjustment(CGF.CurGD);
1539     if (!Adjustment.isZero()) {
1540       unsigned AS = cast<llvm::PointerType>(This->getType())->getAddressSpace();
1541       llvm::Type *charPtrTy = CGF.Int8Ty->getPointerTo(AS),
1542                  *thisTy = This->getType();
1543       This = CGF.Builder.CreateBitCast(This, charPtrTy);
1544       assert(Adjustment.isPositive());
1545       This = CGF.Builder.CreateConstInBoundsGEP1_32(CGF.Int8Ty, This,
1546                                                     -Adjustment.getQuantity());
1547       This = CGF.Builder.CreateBitCast(This, thisTy, "this.adjusted");
1548     }
1549   }
1550   setCXXABIThisValue(CGF, This);
1551 
1552   // If this is a function that the ABI specifies returns 'this', initialize
1553   // the return slot to 'this' at the start of the function.
1554   //
1555   // Unlike the setting of return types, this is done within the ABI
1556   // implementation instead of by clients of CGCXXABI because:
1557   // 1) getThisValue is currently protected
1558   // 2) in theory, an ABI could implement 'this' returns some other way;
1559   //    HasThisReturn only specifies a contract, not the implementation
1560   if (HasThisReturn(CGF.CurGD))
1561     CGF.Builder.CreateStore(getThisValue(CGF), CGF.ReturnValue);
1562   else if (hasMostDerivedReturn(CGF.CurGD))
1563     CGF.Builder.CreateStore(CGF.EmitCastToVoidPtr(getThisValue(CGF)),
1564                             CGF.ReturnValue);
1565 
1566   if (isa<CXXConstructorDecl>(MD) && MD->getParent()->getNumVBases()) {
1567     assert(getStructorImplicitParamDecl(CGF) &&
1568            "no implicit parameter for a constructor with virtual bases?");
1569     getStructorImplicitParamValue(CGF)
1570       = CGF.Builder.CreateLoad(
1571           CGF.GetAddrOfLocalVar(getStructorImplicitParamDecl(CGF)),
1572           "is_most_derived");
1573   }
1574 
1575   if (isDeletingDtor(CGF.CurGD)) {
1576     assert(getStructorImplicitParamDecl(CGF) &&
1577            "no implicit parameter for a deleting destructor?");
1578     getStructorImplicitParamValue(CGF)
1579       = CGF.Builder.CreateLoad(
1580           CGF.GetAddrOfLocalVar(getStructorImplicitParamDecl(CGF)),
1581           "should_call_delete");
1582   }
1583 }
1584 
getImplicitConstructorArgs(CodeGenFunction & CGF,const CXXConstructorDecl * D,CXXCtorType Type,bool ForVirtualBase,bool Delegating)1585 CGCXXABI::AddedStructorArgs MicrosoftCXXABI::getImplicitConstructorArgs(
1586     CodeGenFunction &CGF, const CXXConstructorDecl *D, CXXCtorType Type,
1587     bool ForVirtualBase, bool Delegating) {
1588   assert(Type == Ctor_Complete || Type == Ctor_Base);
1589 
1590   // Check if we need a 'most_derived' parameter.
1591   if (!D->getParent()->getNumVBases())
1592     return AddedStructorArgs{};
1593 
1594   // Add the 'most_derived' argument second if we are variadic or last if not.
1595   const FunctionProtoType *FPT = D->getType()->castAs<FunctionProtoType>();
1596   llvm::Value *MostDerivedArg;
1597   if (Delegating) {
1598     MostDerivedArg = getStructorImplicitParamValue(CGF);
1599   } else {
1600     MostDerivedArg = llvm::ConstantInt::get(CGM.Int32Ty, Type == Ctor_Complete);
1601   }
1602   if (FPT->isVariadic()) {
1603     return AddedStructorArgs::prefix({{MostDerivedArg, getContext().IntTy}});
1604   }
1605   return AddedStructorArgs::suffix({{MostDerivedArg, getContext().IntTy}});
1606 }
1607 
getCXXDestructorImplicitParam(CodeGenFunction & CGF,const CXXDestructorDecl * DD,CXXDtorType Type,bool ForVirtualBase,bool Delegating)1608 llvm::Value *MicrosoftCXXABI::getCXXDestructorImplicitParam(
1609     CodeGenFunction &CGF, const CXXDestructorDecl *DD, CXXDtorType Type,
1610     bool ForVirtualBase, bool Delegating) {
1611   return nullptr;
1612 }
1613 
EmitDestructorCall(CodeGenFunction & CGF,const CXXDestructorDecl * DD,CXXDtorType Type,bool ForVirtualBase,bool Delegating,Address This,QualType ThisTy)1614 void MicrosoftCXXABI::EmitDestructorCall(CodeGenFunction &CGF,
1615                                          const CXXDestructorDecl *DD,
1616                                          CXXDtorType Type, bool ForVirtualBase,
1617                                          bool Delegating, Address This,
1618                                          QualType ThisTy) {
1619   // Use the base destructor variant in place of the complete destructor variant
1620   // if the class has no virtual bases. This effectively implements some of the
1621   // -mconstructor-aliases optimization, but as part of the MS C++ ABI.
1622   if (Type == Dtor_Complete && DD->getParent()->getNumVBases() == 0)
1623     Type = Dtor_Base;
1624 
1625   GlobalDecl GD(DD, Type);
1626   CGCallee Callee = CGCallee::forDirect(CGM.getAddrOfCXXStructor(GD), GD);
1627 
1628   if (DD->isVirtual()) {
1629     assert(Type != CXXDtorType::Dtor_Deleting &&
1630            "The deleting destructor should only be called via a virtual call");
1631     This = adjustThisArgumentForVirtualFunctionCall(CGF, GlobalDecl(DD, Type),
1632                                                     This, false);
1633   }
1634 
1635   llvm::BasicBlock *BaseDtorEndBB = nullptr;
1636   if (ForVirtualBase && isa<CXXConstructorDecl>(CGF.CurCodeDecl)) {
1637     BaseDtorEndBB = EmitDtorCompleteObjectHandler(CGF);
1638   }
1639 
1640   llvm::Value *Implicit =
1641       getCXXDestructorImplicitParam(CGF, DD, Type, ForVirtualBase,
1642                                     Delegating); // = nullptr
1643   CGF.EmitCXXDestructorCall(GD, Callee, This.getPointer(), ThisTy,
1644                             /*ImplicitParam=*/Implicit,
1645                             /*ImplicitParamTy=*/QualType(), nullptr);
1646   if (BaseDtorEndBB) {
1647     // Complete object handler should continue to be the remaining
1648     CGF.Builder.CreateBr(BaseDtorEndBB);
1649     CGF.EmitBlock(BaseDtorEndBB);
1650   }
1651 }
1652 
emitVTableTypeMetadata(const VPtrInfo & Info,const CXXRecordDecl * RD,llvm::GlobalVariable * VTable)1653 void MicrosoftCXXABI::emitVTableTypeMetadata(const VPtrInfo &Info,
1654                                              const CXXRecordDecl *RD,
1655                                              llvm::GlobalVariable *VTable) {
1656   if (!CGM.getCodeGenOpts().LTOUnit)
1657     return;
1658 
1659   // TODO: Should VirtualFunctionElimination also be supported here?
1660   // See similar handling in CodeGenModule::EmitVTableTypeMetadata.
1661   if (CGM.getCodeGenOpts().WholeProgramVTables) {
1662     llvm::DenseSet<const CXXRecordDecl *> Visited;
1663     llvm::GlobalObject::VCallVisibility TypeVis =
1664         CGM.GetVCallVisibilityLevel(RD, Visited);
1665     if (TypeVis != llvm::GlobalObject::VCallVisibilityPublic)
1666       VTable->setVCallVisibilityMetadata(TypeVis);
1667   }
1668 
1669   // The location of the first virtual function pointer in the virtual table,
1670   // aka the "address point" on Itanium. This is at offset 0 if RTTI is
1671   // disabled, or sizeof(void*) if RTTI is enabled.
1672   CharUnits AddressPoint =
1673       getContext().getLangOpts().RTTIData
1674           ? getContext().toCharUnitsFromBits(
1675                 getContext().getTargetInfo().getPointerWidth(0))
1676           : CharUnits::Zero();
1677 
1678   if (Info.PathToIntroducingObject.empty()) {
1679     CGM.AddVTableTypeMetadata(VTable, AddressPoint, RD);
1680     return;
1681   }
1682 
1683   // Add a bitset entry for the least derived base belonging to this vftable.
1684   CGM.AddVTableTypeMetadata(VTable, AddressPoint,
1685                             Info.PathToIntroducingObject.back());
1686 
1687   // Add a bitset entry for each derived class that is laid out at the same
1688   // offset as the least derived base.
1689   for (unsigned I = Info.PathToIntroducingObject.size() - 1; I != 0; --I) {
1690     const CXXRecordDecl *DerivedRD = Info.PathToIntroducingObject[I - 1];
1691     const CXXRecordDecl *BaseRD = Info.PathToIntroducingObject[I];
1692 
1693     const ASTRecordLayout &Layout =
1694         getContext().getASTRecordLayout(DerivedRD);
1695     CharUnits Offset;
1696     auto VBI = Layout.getVBaseOffsetsMap().find(BaseRD);
1697     if (VBI == Layout.getVBaseOffsetsMap().end())
1698       Offset = Layout.getBaseClassOffset(BaseRD);
1699     else
1700       Offset = VBI->second.VBaseOffset;
1701     if (!Offset.isZero())
1702       return;
1703     CGM.AddVTableTypeMetadata(VTable, AddressPoint, DerivedRD);
1704   }
1705 
1706   // Finally do the same for the most derived class.
1707   if (Info.FullOffsetInMDC.isZero())
1708     CGM.AddVTableTypeMetadata(VTable, AddressPoint, RD);
1709 }
1710 
emitVTableDefinitions(CodeGenVTables & CGVT,const CXXRecordDecl * RD)1711 void MicrosoftCXXABI::emitVTableDefinitions(CodeGenVTables &CGVT,
1712                                             const CXXRecordDecl *RD) {
1713   MicrosoftVTableContext &VFTContext = CGM.getMicrosoftVTableContext();
1714   const VPtrInfoVector &VFPtrs = VFTContext.getVFPtrOffsets(RD);
1715 
1716   for (const std::unique_ptr<VPtrInfo>& Info : VFPtrs) {
1717     llvm::GlobalVariable *VTable = getAddrOfVTable(RD, Info->FullOffsetInMDC);
1718     if (VTable->hasInitializer())
1719       continue;
1720 
1721     const VTableLayout &VTLayout =
1722       VFTContext.getVFTableLayout(RD, Info->FullOffsetInMDC);
1723 
1724     llvm::Constant *RTTI = nullptr;
1725     if (any_of(VTLayout.vtable_components(),
1726                [](const VTableComponent &VTC) { return VTC.isRTTIKind(); }))
1727       RTTI = getMSCompleteObjectLocator(RD, *Info);
1728 
1729     ConstantInitBuilder builder(CGM);
1730     auto components = builder.beginStruct();
1731     CGVT.createVTableInitializer(components, VTLayout, RTTI,
1732                                  VTable->hasLocalLinkage());
1733     components.finishAndSetAsInitializer(VTable);
1734 
1735     emitVTableTypeMetadata(*Info, RD, VTable);
1736   }
1737 }
1738 
isVirtualOffsetNeededForVTableField(CodeGenFunction & CGF,CodeGenFunction::VPtr Vptr)1739 bool MicrosoftCXXABI::isVirtualOffsetNeededForVTableField(
1740     CodeGenFunction &CGF, CodeGenFunction::VPtr Vptr) {
1741   return Vptr.NearestVBase != nullptr;
1742 }
1743 
getVTableAddressPointInStructor(CodeGenFunction & CGF,const CXXRecordDecl * VTableClass,BaseSubobject Base,const CXXRecordDecl * NearestVBase)1744 llvm::Value *MicrosoftCXXABI::getVTableAddressPointInStructor(
1745     CodeGenFunction &CGF, const CXXRecordDecl *VTableClass, BaseSubobject Base,
1746     const CXXRecordDecl *NearestVBase) {
1747   llvm::Constant *VTableAddressPoint = getVTableAddressPoint(Base, VTableClass);
1748   if (!VTableAddressPoint) {
1749     assert(Base.getBase()->getNumVBases() &&
1750            !getContext().getASTRecordLayout(Base.getBase()).hasOwnVFPtr());
1751   }
1752   return VTableAddressPoint;
1753 }
1754 
mangleVFTableName(MicrosoftMangleContext & MangleContext,const CXXRecordDecl * RD,const VPtrInfo & VFPtr,SmallString<256> & Name)1755 static void mangleVFTableName(MicrosoftMangleContext &MangleContext,
1756                               const CXXRecordDecl *RD, const VPtrInfo &VFPtr,
1757                               SmallString<256> &Name) {
1758   llvm::raw_svector_ostream Out(Name);
1759   MangleContext.mangleCXXVFTable(RD, VFPtr.MangledPath, Out);
1760 }
1761 
1762 llvm::Constant *
getVTableAddressPoint(BaseSubobject Base,const CXXRecordDecl * VTableClass)1763 MicrosoftCXXABI::getVTableAddressPoint(BaseSubobject Base,
1764                                        const CXXRecordDecl *VTableClass) {
1765   (void)getAddrOfVTable(VTableClass, Base.getBaseOffset());
1766   VFTableIdTy ID(VTableClass, Base.getBaseOffset());
1767   return VFTablesMap[ID];
1768 }
1769 
getVTableAddressPointForConstExpr(BaseSubobject Base,const CXXRecordDecl * VTableClass)1770 llvm::Constant *MicrosoftCXXABI::getVTableAddressPointForConstExpr(
1771     BaseSubobject Base, const CXXRecordDecl *VTableClass) {
1772   llvm::Constant *VFTable = getVTableAddressPoint(Base, VTableClass);
1773   assert(VFTable && "Couldn't find a vftable for the given base?");
1774   return VFTable;
1775 }
1776 
getAddrOfVTable(const CXXRecordDecl * RD,CharUnits VPtrOffset)1777 llvm::GlobalVariable *MicrosoftCXXABI::getAddrOfVTable(const CXXRecordDecl *RD,
1778                                                        CharUnits VPtrOffset) {
1779   // getAddrOfVTable may return 0 if asked to get an address of a vtable which
1780   // shouldn't be used in the given record type. We want to cache this result in
1781   // VFTablesMap, thus a simple zero check is not sufficient.
1782 
1783   VFTableIdTy ID(RD, VPtrOffset);
1784   VTablesMapTy::iterator I;
1785   bool Inserted;
1786   std::tie(I, Inserted) = VTablesMap.insert(std::make_pair(ID, nullptr));
1787   if (!Inserted)
1788     return I->second;
1789 
1790   llvm::GlobalVariable *&VTable = I->second;
1791 
1792   MicrosoftVTableContext &VTContext = CGM.getMicrosoftVTableContext();
1793   const VPtrInfoVector &VFPtrs = VTContext.getVFPtrOffsets(RD);
1794 
1795   if (DeferredVFTables.insert(RD).second) {
1796     // We haven't processed this record type before.
1797     // Queue up this vtable for possible deferred emission.
1798     CGM.addDeferredVTable(RD);
1799 
1800 #ifndef NDEBUG
1801     // Create all the vftables at once in order to make sure each vftable has
1802     // a unique mangled name.
1803     llvm::StringSet<> ObservedMangledNames;
1804     for (size_t J = 0, F = VFPtrs.size(); J != F; ++J) {
1805       SmallString<256> Name;
1806       mangleVFTableName(getMangleContext(), RD, *VFPtrs[J], Name);
1807       if (!ObservedMangledNames.insert(Name.str()).second)
1808         llvm_unreachable("Already saw this mangling before?");
1809     }
1810 #endif
1811   }
1812 
1813   const std::unique_ptr<VPtrInfo> *VFPtrI = std::find_if(
1814       VFPtrs.begin(), VFPtrs.end(), [&](const std::unique_ptr<VPtrInfo>& VPI) {
1815         return VPI->FullOffsetInMDC == VPtrOffset;
1816       });
1817   if (VFPtrI == VFPtrs.end()) {
1818     VFTablesMap[ID] = nullptr;
1819     return nullptr;
1820   }
1821   const std::unique_ptr<VPtrInfo> &VFPtr = *VFPtrI;
1822 
1823   SmallString<256> VFTableName;
1824   mangleVFTableName(getMangleContext(), RD, *VFPtr, VFTableName);
1825 
1826   // Classes marked __declspec(dllimport) need vftables generated on the
1827   // import-side in order to support features like constexpr.  No other
1828   // translation unit relies on the emission of the local vftable, translation
1829   // units are expected to generate them as needed.
1830   //
1831   // Because of this unique behavior, we maintain this logic here instead of
1832   // getVTableLinkage.
1833   llvm::GlobalValue::LinkageTypes VFTableLinkage =
1834       RD->hasAttr<DLLImportAttr>() ? llvm::GlobalValue::LinkOnceODRLinkage
1835                                    : CGM.getVTableLinkage(RD);
1836   bool VFTableComesFromAnotherTU =
1837       llvm::GlobalValue::isAvailableExternallyLinkage(VFTableLinkage) ||
1838       llvm::GlobalValue::isExternalLinkage(VFTableLinkage);
1839   bool VTableAliasIsRequred =
1840       !VFTableComesFromAnotherTU && getContext().getLangOpts().RTTIData;
1841 
1842   if (llvm::GlobalValue *VFTable =
1843           CGM.getModule().getNamedGlobal(VFTableName)) {
1844     VFTablesMap[ID] = VFTable;
1845     VTable = VTableAliasIsRequred
1846                  ? cast<llvm::GlobalVariable>(
1847                        cast<llvm::GlobalAlias>(VFTable)->getBaseObject())
1848                  : cast<llvm::GlobalVariable>(VFTable);
1849     return VTable;
1850   }
1851 
1852   const VTableLayout &VTLayout =
1853       VTContext.getVFTableLayout(RD, VFPtr->FullOffsetInMDC);
1854   llvm::GlobalValue::LinkageTypes VTableLinkage =
1855       VTableAliasIsRequred ? llvm::GlobalValue::PrivateLinkage : VFTableLinkage;
1856 
1857   StringRef VTableName = VTableAliasIsRequred ? StringRef() : VFTableName.str();
1858 
1859   llvm::Type *VTableType = CGM.getVTables().getVTableType(VTLayout);
1860 
1861   // Create a backing variable for the contents of VTable.  The VTable may
1862   // or may not include space for a pointer to RTTI data.
1863   llvm::GlobalValue *VFTable;
1864   VTable = new llvm::GlobalVariable(CGM.getModule(), VTableType,
1865                                     /*isConstant=*/true, VTableLinkage,
1866                                     /*Initializer=*/nullptr, VTableName);
1867   VTable->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
1868 
1869   llvm::Comdat *C = nullptr;
1870   if (!VFTableComesFromAnotherTU &&
1871       (llvm::GlobalValue::isWeakForLinker(VFTableLinkage) ||
1872        (llvm::GlobalValue::isLocalLinkage(VFTableLinkage) &&
1873         VTableAliasIsRequred)))
1874     C = CGM.getModule().getOrInsertComdat(VFTableName.str());
1875 
1876   // Only insert a pointer into the VFTable for RTTI data if we are not
1877   // importing it.  We never reference the RTTI data directly so there is no
1878   // need to make room for it.
1879   if (VTableAliasIsRequred) {
1880     llvm::Value *GEPIndices[] = {llvm::ConstantInt::get(CGM.Int32Ty, 0),
1881                                  llvm::ConstantInt::get(CGM.Int32Ty, 0),
1882                                  llvm::ConstantInt::get(CGM.Int32Ty, 1)};
1883     // Create a GEP which points just after the first entry in the VFTable,
1884     // this should be the location of the first virtual method.
1885     llvm::Constant *VTableGEP = llvm::ConstantExpr::getInBoundsGetElementPtr(
1886         VTable->getValueType(), VTable, GEPIndices);
1887     if (llvm::GlobalValue::isWeakForLinker(VFTableLinkage)) {
1888       VFTableLinkage = llvm::GlobalValue::ExternalLinkage;
1889       if (C)
1890         C->setSelectionKind(llvm::Comdat::Largest);
1891     }
1892     VFTable = llvm::GlobalAlias::create(CGM.Int8PtrTy,
1893                                         /*AddressSpace=*/0, VFTableLinkage,
1894                                         VFTableName.str(), VTableGEP,
1895                                         &CGM.getModule());
1896     VFTable->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
1897   } else {
1898     // We don't need a GlobalAlias to be a symbol for the VTable if we won't
1899     // be referencing any RTTI data.
1900     // The GlobalVariable will end up being an appropriate definition of the
1901     // VFTable.
1902     VFTable = VTable;
1903   }
1904   if (C)
1905     VTable->setComdat(C);
1906 
1907   if (RD->hasAttr<DLLExportAttr>())
1908     VFTable->setDLLStorageClass(llvm::GlobalValue::DLLExportStorageClass);
1909 
1910   VFTablesMap[ID] = VFTable;
1911   return VTable;
1912 }
1913 
getVirtualFunctionPointer(CodeGenFunction & CGF,GlobalDecl GD,Address This,llvm::Type * Ty,SourceLocation Loc)1914 CGCallee MicrosoftCXXABI::getVirtualFunctionPointer(CodeGenFunction &CGF,
1915                                                     GlobalDecl GD,
1916                                                     Address This,
1917                                                     llvm::Type *Ty,
1918                                                     SourceLocation Loc) {
1919   CGBuilderTy &Builder = CGF.Builder;
1920 
1921   Ty = Ty->getPointerTo();
1922   Address VPtr =
1923       adjustThisArgumentForVirtualFunctionCall(CGF, GD, This, true);
1924 
1925   auto *MethodDecl = cast<CXXMethodDecl>(GD.getDecl());
1926   llvm::Value *VTable = CGF.GetVTablePtr(VPtr, Ty->getPointerTo(),
1927                                          MethodDecl->getParent());
1928 
1929   MicrosoftVTableContext &VFTContext = CGM.getMicrosoftVTableContext();
1930   MethodVFTableLocation ML = VFTContext.getMethodVFTableLocation(GD);
1931 
1932   // Compute the identity of the most derived class whose virtual table is
1933   // located at the MethodVFTableLocation ML.
1934   auto getObjectWithVPtr = [&] {
1935     return llvm::find_if(VFTContext.getVFPtrOffsets(
1936                              ML.VBase ? ML.VBase : MethodDecl->getParent()),
1937                          [&](const std::unique_ptr<VPtrInfo> &Info) {
1938                            return Info->FullOffsetInMDC == ML.VFPtrOffset;
1939                          })
1940         ->get()
1941         ->ObjectWithVPtr;
1942   };
1943 
1944   llvm::Value *VFunc;
1945   if (CGF.ShouldEmitVTableTypeCheckedLoad(MethodDecl->getParent())) {
1946     VFunc = CGF.EmitVTableTypeCheckedLoad(
1947         getObjectWithVPtr(), VTable,
1948         ML.Index * CGM.getContext().getTargetInfo().getPointerWidth(0) / 8);
1949   } else {
1950     if (CGM.getCodeGenOpts().PrepareForLTO)
1951       CGF.EmitTypeMetadataCodeForVCall(getObjectWithVPtr(), VTable, Loc);
1952 
1953     llvm::Value *VFuncPtr =
1954         Builder.CreateConstInBoundsGEP1_64(Ty, VTable, ML.Index, "vfn");
1955     VFunc = Builder.CreateAlignedLoad(Ty, VFuncPtr, CGF.getPointerAlign());
1956   }
1957 
1958   CGCallee Callee(GD, VFunc);
1959   return Callee;
1960 }
1961 
EmitVirtualDestructorCall(CodeGenFunction & CGF,const CXXDestructorDecl * Dtor,CXXDtorType DtorType,Address This,DeleteOrMemberCallExpr E)1962 llvm::Value *MicrosoftCXXABI::EmitVirtualDestructorCall(
1963     CodeGenFunction &CGF, const CXXDestructorDecl *Dtor, CXXDtorType DtorType,
1964     Address This, DeleteOrMemberCallExpr E) {
1965   auto *CE = E.dyn_cast<const CXXMemberCallExpr *>();
1966   auto *D = E.dyn_cast<const CXXDeleteExpr *>();
1967   assert((CE != nullptr) ^ (D != nullptr));
1968   assert(CE == nullptr || CE->arg_begin() == CE->arg_end());
1969   assert(DtorType == Dtor_Deleting || DtorType == Dtor_Complete);
1970 
1971   // We have only one destructor in the vftable but can get both behaviors
1972   // by passing an implicit int parameter.
1973   GlobalDecl GD(Dtor, Dtor_Deleting);
1974   const CGFunctionInfo *FInfo =
1975       &CGM.getTypes().arrangeCXXStructorDeclaration(GD);
1976   llvm::FunctionType *Ty = CGF.CGM.getTypes().GetFunctionType(*FInfo);
1977   CGCallee Callee = CGCallee::forVirtual(CE, GD, This, Ty);
1978 
1979   ASTContext &Context = getContext();
1980   llvm::Value *ImplicitParam = llvm::ConstantInt::get(
1981       llvm::IntegerType::getInt32Ty(CGF.getLLVMContext()),
1982       DtorType == Dtor_Deleting);
1983 
1984   QualType ThisTy;
1985   if (CE) {
1986     ThisTy = CE->getObjectType();
1987   } else {
1988     ThisTy = D->getDestroyedType();
1989   }
1990 
1991   This = adjustThisArgumentForVirtualFunctionCall(CGF, GD, This, true);
1992   RValue RV = CGF.EmitCXXDestructorCall(GD, Callee, This.getPointer(), ThisTy,
1993                                         ImplicitParam, Context.IntTy, CE);
1994   return RV.getScalarVal();
1995 }
1996 
1997 const VBTableGlobals &
enumerateVBTables(const CXXRecordDecl * RD)1998 MicrosoftCXXABI::enumerateVBTables(const CXXRecordDecl *RD) {
1999   // At this layer, we can key the cache off of a single class, which is much
2000   // easier than caching each vbtable individually.
2001   llvm::DenseMap<const CXXRecordDecl*, VBTableGlobals>::iterator Entry;
2002   bool Added;
2003   std::tie(Entry, Added) =
2004       VBTablesMap.insert(std::make_pair(RD, VBTableGlobals()));
2005   VBTableGlobals &VBGlobals = Entry->second;
2006   if (!Added)
2007     return VBGlobals;
2008 
2009   MicrosoftVTableContext &Context = CGM.getMicrosoftVTableContext();
2010   VBGlobals.VBTables = &Context.enumerateVBTables(RD);
2011 
2012   // Cache the globals for all vbtables so we don't have to recompute the
2013   // mangled names.
2014   llvm::GlobalVariable::LinkageTypes Linkage = CGM.getVTableLinkage(RD);
2015   for (VPtrInfoVector::const_iterator I = VBGlobals.VBTables->begin(),
2016                                       E = VBGlobals.VBTables->end();
2017        I != E; ++I) {
2018     VBGlobals.Globals.push_back(getAddrOfVBTable(**I, RD, Linkage));
2019   }
2020 
2021   return VBGlobals;
2022 }
2023 
2024 llvm::Function *
EmitVirtualMemPtrThunk(const CXXMethodDecl * MD,const MethodVFTableLocation & ML)2025 MicrosoftCXXABI::EmitVirtualMemPtrThunk(const CXXMethodDecl *MD,
2026                                         const MethodVFTableLocation &ML) {
2027   assert(!isa<CXXConstructorDecl>(MD) && !isa<CXXDestructorDecl>(MD) &&
2028          "can't form pointers to ctors or virtual dtors");
2029 
2030   // Calculate the mangled name.
2031   SmallString<256> ThunkName;
2032   llvm::raw_svector_ostream Out(ThunkName);
2033   getMangleContext().mangleVirtualMemPtrThunk(MD, ML, Out);
2034 
2035   // If the thunk has been generated previously, just return it.
2036   if (llvm::GlobalValue *GV = CGM.getModule().getNamedValue(ThunkName))
2037     return cast<llvm::Function>(GV);
2038 
2039   // Create the llvm::Function.
2040   const CGFunctionInfo &FnInfo =
2041       CGM.getTypes().arrangeUnprototypedMustTailThunk(MD);
2042   llvm::FunctionType *ThunkTy = CGM.getTypes().GetFunctionType(FnInfo);
2043   llvm::Function *ThunkFn =
2044       llvm::Function::Create(ThunkTy, llvm::Function::ExternalLinkage,
2045                              ThunkName.str(), &CGM.getModule());
2046   assert(ThunkFn->getName() == ThunkName && "name was uniqued!");
2047 
2048   ThunkFn->setLinkage(MD->isExternallyVisible()
2049                           ? llvm::GlobalValue::LinkOnceODRLinkage
2050                           : llvm::GlobalValue::InternalLinkage);
2051   if (MD->isExternallyVisible())
2052     ThunkFn->setComdat(CGM.getModule().getOrInsertComdat(ThunkFn->getName()));
2053 
2054   CGM.SetLLVMFunctionAttributes(MD, FnInfo, ThunkFn, /*IsThunk=*/false);
2055   CGM.SetLLVMFunctionAttributesForDefinition(MD, ThunkFn);
2056 
2057   // Add the "thunk" attribute so that LLVM knows that the return type is
2058   // meaningless. These thunks can be used to call functions with differing
2059   // return types, and the caller is required to cast the prototype
2060   // appropriately to extract the correct value.
2061   ThunkFn->addFnAttr("thunk");
2062 
2063   // These thunks can be compared, so they are not unnamed.
2064   ThunkFn->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::None);
2065 
2066   // Start codegen.
2067   CodeGenFunction CGF(CGM);
2068   CGF.CurGD = GlobalDecl(MD);
2069   CGF.CurFuncIsThunk = true;
2070 
2071   // Build FunctionArgs, but only include the implicit 'this' parameter
2072   // declaration.
2073   FunctionArgList FunctionArgs;
2074   buildThisParam(CGF, FunctionArgs);
2075 
2076   // Start defining the function.
2077   CGF.StartFunction(GlobalDecl(), FnInfo.getReturnType(), ThunkFn, FnInfo,
2078                     FunctionArgs, MD->getLocation(), SourceLocation());
2079   setCXXABIThisValue(CGF, loadIncomingCXXThis(CGF));
2080 
2081   // Load the vfptr and then callee from the vftable.  The callee should have
2082   // adjusted 'this' so that the vfptr is at offset zero.
2083   llvm::Type *ThunkPtrTy = ThunkTy->getPointerTo();
2084   llvm::Value *VTable = CGF.GetVTablePtr(
2085       getThisAddress(CGF), ThunkPtrTy->getPointerTo(), MD->getParent());
2086 
2087   llvm::Value *VFuncPtr = CGF.Builder.CreateConstInBoundsGEP1_64(
2088       ThunkPtrTy, VTable, ML.Index, "vfn");
2089   llvm::Value *Callee =
2090     CGF.Builder.CreateAlignedLoad(ThunkPtrTy, VFuncPtr, CGF.getPointerAlign());
2091 
2092   CGF.EmitMustTailThunk(MD, getThisValue(CGF), {ThunkTy, Callee});
2093 
2094   return ThunkFn;
2095 }
2096 
emitVirtualInheritanceTables(const CXXRecordDecl * RD)2097 void MicrosoftCXXABI::emitVirtualInheritanceTables(const CXXRecordDecl *RD) {
2098   const VBTableGlobals &VBGlobals = enumerateVBTables(RD);
2099   for (unsigned I = 0, E = VBGlobals.VBTables->size(); I != E; ++I) {
2100     const std::unique_ptr<VPtrInfo>& VBT = (*VBGlobals.VBTables)[I];
2101     llvm::GlobalVariable *GV = VBGlobals.Globals[I];
2102     if (GV->isDeclaration())
2103       emitVBTableDefinition(*VBT, RD, GV);
2104   }
2105 }
2106 
2107 llvm::GlobalVariable *
getAddrOfVBTable(const VPtrInfo & VBT,const CXXRecordDecl * RD,llvm::GlobalVariable::LinkageTypes Linkage)2108 MicrosoftCXXABI::getAddrOfVBTable(const VPtrInfo &VBT, const CXXRecordDecl *RD,
2109                                   llvm::GlobalVariable::LinkageTypes Linkage) {
2110   SmallString<256> OutName;
2111   llvm::raw_svector_ostream Out(OutName);
2112   getMangleContext().mangleCXXVBTable(RD, VBT.MangledPath, Out);
2113   StringRef Name = OutName.str();
2114 
2115   llvm::ArrayType *VBTableType =
2116       llvm::ArrayType::get(CGM.IntTy, 1 + VBT.ObjectWithVPtr->getNumVBases());
2117 
2118   assert(!CGM.getModule().getNamedGlobal(Name) &&
2119          "vbtable with this name already exists: mangling bug?");
2120   CharUnits Alignment =
2121       CGM.getContext().getTypeAlignInChars(CGM.getContext().IntTy);
2122   llvm::GlobalVariable *GV = CGM.CreateOrReplaceCXXRuntimeVariable(
2123       Name, VBTableType, Linkage, Alignment.getQuantity());
2124   GV->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
2125 
2126   if (RD->hasAttr<DLLImportAttr>())
2127     GV->setDLLStorageClass(llvm::GlobalValue::DLLImportStorageClass);
2128   else if (RD->hasAttr<DLLExportAttr>())
2129     GV->setDLLStorageClass(llvm::GlobalValue::DLLExportStorageClass);
2130 
2131   if (!GV->hasExternalLinkage())
2132     emitVBTableDefinition(VBT, RD, GV);
2133 
2134   return GV;
2135 }
2136 
emitVBTableDefinition(const VPtrInfo & VBT,const CXXRecordDecl * RD,llvm::GlobalVariable * GV) const2137 void MicrosoftCXXABI::emitVBTableDefinition(const VPtrInfo &VBT,
2138                                             const CXXRecordDecl *RD,
2139                                             llvm::GlobalVariable *GV) const {
2140   const CXXRecordDecl *ObjectWithVPtr = VBT.ObjectWithVPtr;
2141 
2142   assert(RD->getNumVBases() && ObjectWithVPtr->getNumVBases() &&
2143          "should only emit vbtables for classes with vbtables");
2144 
2145   const ASTRecordLayout &BaseLayout =
2146       getContext().getASTRecordLayout(VBT.IntroducingObject);
2147   const ASTRecordLayout &DerivedLayout = getContext().getASTRecordLayout(RD);
2148 
2149   SmallVector<llvm::Constant *, 4> Offsets(1 + ObjectWithVPtr->getNumVBases(),
2150                                            nullptr);
2151 
2152   // The offset from ObjectWithVPtr's vbptr to itself always leads.
2153   CharUnits VBPtrOffset = BaseLayout.getVBPtrOffset();
2154   Offsets[0] = llvm::ConstantInt::get(CGM.IntTy, -VBPtrOffset.getQuantity());
2155 
2156   MicrosoftVTableContext &Context = CGM.getMicrosoftVTableContext();
2157   for (const auto &I : ObjectWithVPtr->vbases()) {
2158     const CXXRecordDecl *VBase = I.getType()->getAsCXXRecordDecl();
2159     CharUnits Offset = DerivedLayout.getVBaseClassOffset(VBase);
2160     assert(!Offset.isNegative());
2161 
2162     // Make it relative to the subobject vbptr.
2163     CharUnits CompleteVBPtrOffset = VBT.NonVirtualOffset + VBPtrOffset;
2164     if (VBT.getVBaseWithVPtr())
2165       CompleteVBPtrOffset +=
2166           DerivedLayout.getVBaseClassOffset(VBT.getVBaseWithVPtr());
2167     Offset -= CompleteVBPtrOffset;
2168 
2169     unsigned VBIndex = Context.getVBTableIndex(ObjectWithVPtr, VBase);
2170     assert(Offsets[VBIndex] == nullptr && "The same vbindex seen twice?");
2171     Offsets[VBIndex] = llvm::ConstantInt::get(CGM.IntTy, Offset.getQuantity());
2172   }
2173 
2174   assert(Offsets.size() ==
2175          cast<llvm::ArrayType>(GV->getValueType())->getNumElements());
2176   llvm::ArrayType *VBTableType =
2177     llvm::ArrayType::get(CGM.IntTy, Offsets.size());
2178   llvm::Constant *Init = llvm::ConstantArray::get(VBTableType, Offsets);
2179   GV->setInitializer(Init);
2180 
2181   if (RD->hasAttr<DLLImportAttr>())
2182     GV->setLinkage(llvm::GlobalVariable::AvailableExternallyLinkage);
2183 }
2184 
performThisAdjustment(CodeGenFunction & CGF,Address This,const ThisAdjustment & TA)2185 llvm::Value *MicrosoftCXXABI::performThisAdjustment(CodeGenFunction &CGF,
2186                                                     Address This,
2187                                                     const ThisAdjustment &TA) {
2188   if (TA.isEmpty())
2189     return This.getPointer();
2190 
2191   This = CGF.Builder.CreateElementBitCast(This, CGF.Int8Ty);
2192 
2193   llvm::Value *V;
2194   if (TA.Virtual.isEmpty()) {
2195     V = This.getPointer();
2196   } else {
2197     assert(TA.Virtual.Microsoft.VtordispOffset < 0);
2198     // Adjust the this argument based on the vtordisp value.
2199     Address VtorDispPtr =
2200         CGF.Builder.CreateConstInBoundsByteGEP(This,
2201                  CharUnits::fromQuantity(TA.Virtual.Microsoft.VtordispOffset));
2202     VtorDispPtr = CGF.Builder.CreateElementBitCast(VtorDispPtr, CGF.Int32Ty);
2203     llvm::Value *VtorDisp = CGF.Builder.CreateLoad(VtorDispPtr, "vtordisp");
2204     V = CGF.Builder.CreateGEP(This.getElementType(), This.getPointer(),
2205                               CGF.Builder.CreateNeg(VtorDisp));
2206 
2207     // Unfortunately, having applied the vtordisp means that we no
2208     // longer really have a known alignment for the vbptr step.
2209     // We'll assume the vbptr is pointer-aligned.
2210 
2211     if (TA.Virtual.Microsoft.VBPtrOffset) {
2212       // If the final overrider is defined in a virtual base other than the one
2213       // that holds the vfptr, we have to use a vtordispex thunk which looks up
2214       // the vbtable of the derived class.
2215       assert(TA.Virtual.Microsoft.VBPtrOffset > 0);
2216       assert(TA.Virtual.Microsoft.VBOffsetOffset >= 0);
2217       llvm::Value *VBPtr;
2218       llvm::Value *VBaseOffset =
2219           GetVBaseOffsetFromVBPtr(CGF, Address(V, CGF.getPointerAlign()),
2220                                   -TA.Virtual.Microsoft.VBPtrOffset,
2221                                   TA.Virtual.Microsoft.VBOffsetOffset, &VBPtr);
2222       V = CGF.Builder.CreateInBoundsGEP(CGF.Int8Ty, VBPtr, VBaseOffset);
2223     }
2224   }
2225 
2226   if (TA.NonVirtual) {
2227     // Non-virtual adjustment might result in a pointer outside the allocated
2228     // object, e.g. if the final overrider class is laid out after the virtual
2229     // base that declares a method in the most derived class.
2230     V = CGF.Builder.CreateConstGEP1_32(CGF.Int8Ty, V, TA.NonVirtual);
2231   }
2232 
2233   // Don't need to bitcast back, the call CodeGen will handle this.
2234   return V;
2235 }
2236 
2237 llvm::Value *
performReturnAdjustment(CodeGenFunction & CGF,Address Ret,const ReturnAdjustment & RA)2238 MicrosoftCXXABI::performReturnAdjustment(CodeGenFunction &CGF, Address Ret,
2239                                          const ReturnAdjustment &RA) {
2240   if (RA.isEmpty())
2241     return Ret.getPointer();
2242 
2243   auto OrigTy = Ret.getType();
2244   Ret = CGF.Builder.CreateElementBitCast(Ret, CGF.Int8Ty);
2245 
2246   llvm::Value *V = Ret.getPointer();
2247   if (RA.Virtual.Microsoft.VBIndex) {
2248     assert(RA.Virtual.Microsoft.VBIndex > 0);
2249     int32_t IntSize = CGF.getIntSize().getQuantity();
2250     llvm::Value *VBPtr;
2251     llvm::Value *VBaseOffset =
2252         GetVBaseOffsetFromVBPtr(CGF, Ret, RA.Virtual.Microsoft.VBPtrOffset,
2253                                 IntSize * RA.Virtual.Microsoft.VBIndex, &VBPtr);
2254     V = CGF.Builder.CreateInBoundsGEP(CGF.Int8Ty, VBPtr, VBaseOffset);
2255   }
2256 
2257   if (RA.NonVirtual)
2258     V = CGF.Builder.CreateConstInBoundsGEP1_32(CGF.Int8Ty, V, RA.NonVirtual);
2259 
2260   // Cast back to the original type.
2261   return CGF.Builder.CreateBitCast(V, OrigTy);
2262 }
2263 
requiresArrayCookie(const CXXDeleteExpr * expr,QualType elementType)2264 bool MicrosoftCXXABI::requiresArrayCookie(const CXXDeleteExpr *expr,
2265                                    QualType elementType) {
2266   // Microsoft seems to completely ignore the possibility of a
2267   // two-argument usual deallocation function.
2268   return elementType.isDestructedType();
2269 }
2270 
requiresArrayCookie(const CXXNewExpr * expr)2271 bool MicrosoftCXXABI::requiresArrayCookie(const CXXNewExpr *expr) {
2272   // Microsoft seems to completely ignore the possibility of a
2273   // two-argument usual deallocation function.
2274   return expr->getAllocatedType().isDestructedType();
2275 }
2276 
getArrayCookieSizeImpl(QualType type)2277 CharUnits MicrosoftCXXABI::getArrayCookieSizeImpl(QualType type) {
2278   // The array cookie is always a size_t; we then pad that out to the
2279   // alignment of the element type.
2280   ASTContext &Ctx = getContext();
2281   return std::max(Ctx.getTypeSizeInChars(Ctx.getSizeType()),
2282                   Ctx.getTypeAlignInChars(type));
2283 }
2284 
readArrayCookieImpl(CodeGenFunction & CGF,Address allocPtr,CharUnits cookieSize)2285 llvm::Value *MicrosoftCXXABI::readArrayCookieImpl(CodeGenFunction &CGF,
2286                                                   Address allocPtr,
2287                                                   CharUnits cookieSize) {
2288   Address numElementsPtr =
2289     CGF.Builder.CreateElementBitCast(allocPtr, CGF.SizeTy);
2290   return CGF.Builder.CreateLoad(numElementsPtr);
2291 }
2292 
InitializeArrayCookie(CodeGenFunction & CGF,Address newPtr,llvm::Value * numElements,const CXXNewExpr * expr,QualType elementType)2293 Address MicrosoftCXXABI::InitializeArrayCookie(CodeGenFunction &CGF,
2294                                                Address newPtr,
2295                                                llvm::Value *numElements,
2296                                                const CXXNewExpr *expr,
2297                                                QualType elementType) {
2298   assert(requiresArrayCookie(expr));
2299 
2300   // The size of the cookie.
2301   CharUnits cookieSize = getArrayCookieSizeImpl(elementType);
2302 
2303   // Compute an offset to the cookie.
2304   Address cookiePtr = newPtr;
2305 
2306   // Write the number of elements into the appropriate slot.
2307   Address numElementsPtr
2308     = CGF.Builder.CreateElementBitCast(cookiePtr, CGF.SizeTy);
2309   CGF.Builder.CreateStore(numElements, numElementsPtr);
2310 
2311   // Finally, compute a pointer to the actual data buffer by skipping
2312   // over the cookie completely.
2313   return CGF.Builder.CreateConstInBoundsByteGEP(newPtr, cookieSize);
2314 }
2315 
emitGlobalDtorWithTLRegDtor(CodeGenFunction & CGF,const VarDecl & VD,llvm::FunctionCallee Dtor,llvm::Constant * Addr)2316 static void emitGlobalDtorWithTLRegDtor(CodeGenFunction &CGF, const VarDecl &VD,
2317                                         llvm::FunctionCallee Dtor,
2318                                         llvm::Constant *Addr) {
2319   // Create a function which calls the destructor.
2320   llvm::Constant *DtorStub = CGF.createAtExitStub(VD, Dtor, Addr);
2321 
2322   // extern "C" int __tlregdtor(void (*f)(void));
2323   llvm::FunctionType *TLRegDtorTy = llvm::FunctionType::get(
2324       CGF.IntTy, DtorStub->getType(), /*isVarArg=*/false);
2325 
2326   llvm::FunctionCallee TLRegDtor = CGF.CGM.CreateRuntimeFunction(
2327       TLRegDtorTy, "__tlregdtor", llvm::AttributeList(), /*Local=*/true);
2328   if (llvm::Function *TLRegDtorFn =
2329           dyn_cast<llvm::Function>(TLRegDtor.getCallee()))
2330     TLRegDtorFn->setDoesNotThrow();
2331 
2332   CGF.EmitNounwindRuntimeCall(TLRegDtor, DtorStub);
2333 }
2334 
registerGlobalDtor(CodeGenFunction & CGF,const VarDecl & D,llvm::FunctionCallee Dtor,llvm::Constant * Addr)2335 void MicrosoftCXXABI::registerGlobalDtor(CodeGenFunction &CGF, const VarDecl &D,
2336                                          llvm::FunctionCallee Dtor,
2337                                          llvm::Constant *Addr) {
2338   if (D.isNoDestroy(CGM.getContext()))
2339     return;
2340 
2341   if (D.getTLSKind())
2342     return emitGlobalDtorWithTLRegDtor(CGF, D, Dtor, Addr);
2343 
2344   // The default behavior is to use atexit.
2345   CGF.registerGlobalDtorWithAtExit(D, Dtor, Addr);
2346 }
2347 
EmitThreadLocalInitFuncs(CodeGenModule & CGM,ArrayRef<const VarDecl * > CXXThreadLocals,ArrayRef<llvm::Function * > CXXThreadLocalInits,ArrayRef<const VarDecl * > CXXThreadLocalInitVars)2348 void MicrosoftCXXABI::EmitThreadLocalInitFuncs(
2349     CodeGenModule &CGM, ArrayRef<const VarDecl *> CXXThreadLocals,
2350     ArrayRef<llvm::Function *> CXXThreadLocalInits,
2351     ArrayRef<const VarDecl *> CXXThreadLocalInitVars) {
2352   if (CXXThreadLocalInits.empty())
2353     return;
2354 
2355   CGM.AppendLinkerOptions(CGM.getTarget().getTriple().getArch() ==
2356                                   llvm::Triple::x86
2357                               ? "/include:___dyn_tls_init@12"
2358                               : "/include:__dyn_tls_init");
2359 
2360   // This will create a GV in the .CRT$XDU section.  It will point to our
2361   // initialization function.  The CRT will call all of these function
2362   // pointers at start-up time and, eventually, at thread-creation time.
2363   auto AddToXDU = [&CGM](llvm::Function *InitFunc) {
2364     llvm::GlobalVariable *InitFuncPtr = new llvm::GlobalVariable(
2365         CGM.getModule(), InitFunc->getType(), /*isConstant=*/true,
2366         llvm::GlobalVariable::InternalLinkage, InitFunc,
2367         Twine(InitFunc->getName(), "$initializer$"));
2368     InitFuncPtr->setSection(".CRT$XDU");
2369     // This variable has discardable linkage, we have to add it to @llvm.used to
2370     // ensure it won't get discarded.
2371     CGM.addUsedGlobal(InitFuncPtr);
2372     return InitFuncPtr;
2373   };
2374 
2375   std::vector<llvm::Function *> NonComdatInits;
2376   for (size_t I = 0, E = CXXThreadLocalInitVars.size(); I != E; ++I) {
2377     llvm::GlobalVariable *GV = cast<llvm::GlobalVariable>(
2378         CGM.GetGlobalValue(CGM.getMangledName(CXXThreadLocalInitVars[I])));
2379     llvm::Function *F = CXXThreadLocalInits[I];
2380 
2381     // If the GV is already in a comdat group, then we have to join it.
2382     if (llvm::Comdat *C = GV->getComdat())
2383       AddToXDU(F)->setComdat(C);
2384     else
2385       NonComdatInits.push_back(F);
2386   }
2387 
2388   if (!NonComdatInits.empty()) {
2389     llvm::FunctionType *FTy =
2390         llvm::FunctionType::get(CGM.VoidTy, /*isVarArg=*/false);
2391     llvm::Function *InitFunc = CGM.CreateGlobalInitOrCleanUpFunction(
2392         FTy, "__tls_init", CGM.getTypes().arrangeNullaryFunction(),
2393         SourceLocation(), /*TLS=*/true);
2394     CodeGenFunction(CGM).GenerateCXXGlobalInitFunc(InitFunc, NonComdatInits);
2395 
2396     AddToXDU(InitFunc);
2397   }
2398 }
2399 
EmitThreadLocalVarDeclLValue(CodeGenFunction & CGF,const VarDecl * VD,QualType LValType)2400 LValue MicrosoftCXXABI::EmitThreadLocalVarDeclLValue(CodeGenFunction &CGF,
2401                                                      const VarDecl *VD,
2402                                                      QualType LValType) {
2403   CGF.CGM.ErrorUnsupported(VD, "thread wrappers");
2404   return LValue();
2405 }
2406 
getInitThreadEpochPtr(CodeGenModule & CGM)2407 static ConstantAddress getInitThreadEpochPtr(CodeGenModule &CGM) {
2408   StringRef VarName("_Init_thread_epoch");
2409   CharUnits Align = CGM.getIntAlign();
2410   if (auto *GV = CGM.getModule().getNamedGlobal(VarName))
2411     return ConstantAddress(GV, Align);
2412   auto *GV = new llvm::GlobalVariable(
2413       CGM.getModule(), CGM.IntTy,
2414       /*isConstant=*/false, llvm::GlobalVariable::ExternalLinkage,
2415       /*Initializer=*/nullptr, VarName,
2416       /*InsertBefore=*/nullptr, llvm::GlobalVariable::GeneralDynamicTLSModel);
2417   GV->setAlignment(Align.getAsAlign());
2418   return ConstantAddress(GV, Align);
2419 }
2420 
getInitThreadHeaderFn(CodeGenModule & CGM)2421 static llvm::FunctionCallee getInitThreadHeaderFn(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_header",
2427       llvm::AttributeList::get(CGM.getLLVMContext(),
2428                                llvm::AttributeList::FunctionIndex,
2429                                llvm::Attribute::NoUnwind),
2430       /*Local=*/true);
2431 }
2432 
getInitThreadFooterFn(CodeGenModule & CGM)2433 static llvm::FunctionCallee getInitThreadFooterFn(CodeGenModule &CGM) {
2434   llvm::FunctionType *FTy =
2435       llvm::FunctionType::get(llvm::Type::getVoidTy(CGM.getLLVMContext()),
2436                               CGM.IntTy->getPointerTo(), /*isVarArg=*/false);
2437   return CGM.CreateRuntimeFunction(
2438       FTy, "_Init_thread_footer",
2439       llvm::AttributeList::get(CGM.getLLVMContext(),
2440                                llvm::AttributeList::FunctionIndex,
2441                                llvm::Attribute::NoUnwind),
2442       /*Local=*/true);
2443 }
2444 
getInitThreadAbortFn(CodeGenModule & CGM)2445 static llvm::FunctionCallee getInitThreadAbortFn(CodeGenModule &CGM) {
2446   llvm::FunctionType *FTy =
2447       llvm::FunctionType::get(llvm::Type::getVoidTy(CGM.getLLVMContext()),
2448                               CGM.IntTy->getPointerTo(), /*isVarArg=*/false);
2449   return CGM.CreateRuntimeFunction(
2450       FTy, "_Init_thread_abort",
2451       llvm::AttributeList::get(CGM.getLLVMContext(),
2452                                llvm::AttributeList::FunctionIndex,
2453                                llvm::Attribute::NoUnwind),
2454       /*Local=*/true);
2455 }
2456 
2457 namespace {
2458 struct ResetGuardBit final : EHScopeStack::Cleanup {
2459   Address Guard;
2460   unsigned GuardNum;
ResetGuardBit__anona6ec54210711::ResetGuardBit2461   ResetGuardBit(Address Guard, unsigned GuardNum)
2462       : Guard(Guard), GuardNum(GuardNum) {}
2463 
Emit__anona6ec54210711::ResetGuardBit2464   void Emit(CodeGenFunction &CGF, Flags flags) override {
2465     // Reset the bit in the mask so that the static variable may be
2466     // reinitialized.
2467     CGBuilderTy &Builder = CGF.Builder;
2468     llvm::LoadInst *LI = Builder.CreateLoad(Guard);
2469     llvm::ConstantInt *Mask =
2470         llvm::ConstantInt::get(CGF.IntTy, ~(1ULL << GuardNum));
2471     Builder.CreateStore(Builder.CreateAnd(LI, Mask), Guard);
2472   }
2473 };
2474 
2475 struct CallInitThreadAbort final : EHScopeStack::Cleanup {
2476   llvm::Value *Guard;
CallInitThreadAbort__anona6ec54210711::CallInitThreadAbort2477   CallInitThreadAbort(Address Guard) : Guard(Guard.getPointer()) {}
2478 
Emit__anona6ec54210711::CallInitThreadAbort2479   void Emit(CodeGenFunction &CGF, Flags flags) override {
2480     // Calling _Init_thread_abort will reset the guard's state.
2481     CGF.EmitNounwindRuntimeCall(getInitThreadAbortFn(CGF.CGM), Guard);
2482   }
2483 };
2484 }
2485 
EmitGuardedInit(CodeGenFunction & CGF,const VarDecl & D,llvm::GlobalVariable * GV,bool PerformInit)2486 void MicrosoftCXXABI::EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D,
2487                                       llvm::GlobalVariable *GV,
2488                                       bool PerformInit) {
2489   // MSVC only uses guards for static locals.
2490   if (!D.isStaticLocal()) {
2491     assert(GV->hasWeakLinkage() || GV->hasLinkOnceLinkage());
2492     // GlobalOpt is allowed to discard the initializer, so use linkonce_odr.
2493     llvm::Function *F = CGF.CurFn;
2494     F->setLinkage(llvm::GlobalValue::LinkOnceODRLinkage);
2495     F->setComdat(CGM.getModule().getOrInsertComdat(F->getName()));
2496     CGF.EmitCXXGlobalVarDeclInit(D, GV, PerformInit);
2497     return;
2498   }
2499 
2500   bool ThreadlocalStatic = D.getTLSKind();
2501   bool ThreadsafeStatic = getContext().getLangOpts().ThreadsafeStatics;
2502 
2503   // Thread-safe static variables which aren't thread-specific have a
2504   // per-variable guard.
2505   bool HasPerVariableGuard = ThreadsafeStatic && !ThreadlocalStatic;
2506 
2507   CGBuilderTy &Builder = CGF.Builder;
2508   llvm::IntegerType *GuardTy = CGF.Int32Ty;
2509   llvm::ConstantInt *Zero = llvm::ConstantInt::get(GuardTy, 0);
2510   CharUnits GuardAlign = CharUnits::fromQuantity(4);
2511 
2512   // Get the guard variable for this function if we have one already.
2513   GuardInfo *GI = nullptr;
2514   if (ThreadlocalStatic)
2515     GI = &ThreadLocalGuardVariableMap[D.getDeclContext()];
2516   else if (!ThreadsafeStatic)
2517     GI = &GuardVariableMap[D.getDeclContext()];
2518 
2519   llvm::GlobalVariable *GuardVar = GI ? GI->Guard : nullptr;
2520   unsigned GuardNum;
2521   if (D.isExternallyVisible()) {
2522     // Externally visible variables have to be numbered in Sema to properly
2523     // handle unreachable VarDecls.
2524     GuardNum = getContext().getStaticLocalNumber(&D);
2525     assert(GuardNum > 0);
2526     GuardNum--;
2527   } else if (HasPerVariableGuard) {
2528     GuardNum = ThreadSafeGuardNumMap[D.getDeclContext()]++;
2529   } else {
2530     // Non-externally visible variables are numbered here in CodeGen.
2531     GuardNum = GI->BitIndex++;
2532   }
2533 
2534   if (!HasPerVariableGuard && GuardNum >= 32) {
2535     if (D.isExternallyVisible())
2536       ErrorUnsupportedABI(CGF, "more than 32 guarded initializations");
2537     GuardNum %= 32;
2538     GuardVar = nullptr;
2539   }
2540 
2541   if (!GuardVar) {
2542     // Mangle the name for the guard.
2543     SmallString<256> GuardName;
2544     {
2545       llvm::raw_svector_ostream Out(GuardName);
2546       if (HasPerVariableGuard)
2547         getMangleContext().mangleThreadSafeStaticGuardVariable(&D, GuardNum,
2548                                                                Out);
2549       else
2550         getMangleContext().mangleStaticGuardVariable(&D, Out);
2551     }
2552 
2553     // Create the guard variable with a zero-initializer. Just absorb linkage,
2554     // visibility and dll storage class from the guarded variable.
2555     GuardVar =
2556         new llvm::GlobalVariable(CGM.getModule(), GuardTy, /*isConstant=*/false,
2557                                  GV->getLinkage(), Zero, GuardName.str());
2558     GuardVar->setVisibility(GV->getVisibility());
2559     GuardVar->setDLLStorageClass(GV->getDLLStorageClass());
2560     GuardVar->setAlignment(GuardAlign.getAsAlign());
2561     if (GuardVar->isWeakForLinker())
2562       GuardVar->setComdat(
2563           CGM.getModule().getOrInsertComdat(GuardVar->getName()));
2564     if (D.getTLSKind())
2565       CGM.setTLSMode(GuardVar, D);
2566     if (GI && !HasPerVariableGuard)
2567       GI->Guard = GuardVar;
2568   }
2569 
2570   ConstantAddress GuardAddr(GuardVar, GuardAlign);
2571 
2572   assert(GuardVar->getLinkage() == GV->getLinkage() &&
2573          "static local from the same function had different linkage");
2574 
2575   if (!HasPerVariableGuard) {
2576     // Pseudo code for the test:
2577     // if (!(GuardVar & MyGuardBit)) {
2578     //   GuardVar |= MyGuardBit;
2579     //   ... initialize the object ...;
2580     // }
2581 
2582     // Test our bit from the guard variable.
2583     llvm::ConstantInt *Bit = llvm::ConstantInt::get(GuardTy, 1ULL << GuardNum);
2584     llvm::LoadInst *LI = Builder.CreateLoad(GuardAddr);
2585     llvm::Value *NeedsInit =
2586         Builder.CreateICmpEQ(Builder.CreateAnd(LI, Bit), Zero);
2587     llvm::BasicBlock *InitBlock = CGF.createBasicBlock("init");
2588     llvm::BasicBlock *EndBlock = CGF.createBasicBlock("init.end");
2589     CGF.EmitCXXGuardedInitBranch(NeedsInit, InitBlock, EndBlock,
2590                                  CodeGenFunction::GuardKind::VariableGuard, &D);
2591 
2592     // Set our bit in the guard variable and emit the initializer and add a global
2593     // destructor if appropriate.
2594     CGF.EmitBlock(InitBlock);
2595     Builder.CreateStore(Builder.CreateOr(LI, Bit), GuardAddr);
2596     CGF.EHStack.pushCleanup<ResetGuardBit>(EHCleanup, GuardAddr, GuardNum);
2597     CGF.EmitCXXGlobalVarDeclInit(D, GV, PerformInit);
2598     CGF.PopCleanupBlock();
2599     Builder.CreateBr(EndBlock);
2600 
2601     // Continue.
2602     CGF.EmitBlock(EndBlock);
2603   } else {
2604     // Pseudo code for the test:
2605     // if (TSS > _Init_thread_epoch) {
2606     //   _Init_thread_header(&TSS);
2607     //   if (TSS == -1) {
2608     //     ... initialize the object ...;
2609     //     _Init_thread_footer(&TSS);
2610     //   }
2611     // }
2612     //
2613     // The algorithm is almost identical to what can be found in the appendix
2614     // found in N2325.
2615 
2616     // This BasicBLock determines whether or not we have any work to do.
2617     llvm::LoadInst *FirstGuardLoad = Builder.CreateLoad(GuardAddr);
2618     FirstGuardLoad->setOrdering(llvm::AtomicOrdering::Unordered);
2619     llvm::LoadInst *InitThreadEpoch =
2620         Builder.CreateLoad(getInitThreadEpochPtr(CGM));
2621     llvm::Value *IsUninitialized =
2622         Builder.CreateICmpSGT(FirstGuardLoad, InitThreadEpoch);
2623     llvm::BasicBlock *AttemptInitBlock = CGF.createBasicBlock("init.attempt");
2624     llvm::BasicBlock *EndBlock = CGF.createBasicBlock("init.end");
2625     CGF.EmitCXXGuardedInitBranch(IsUninitialized, AttemptInitBlock, EndBlock,
2626                                  CodeGenFunction::GuardKind::VariableGuard, &D);
2627 
2628     // This BasicBlock attempts to determine whether or not this thread is
2629     // responsible for doing the initialization.
2630     CGF.EmitBlock(AttemptInitBlock);
2631     CGF.EmitNounwindRuntimeCall(getInitThreadHeaderFn(CGM),
2632                                 GuardAddr.getPointer());
2633     llvm::LoadInst *SecondGuardLoad = Builder.CreateLoad(GuardAddr);
2634     SecondGuardLoad->setOrdering(llvm::AtomicOrdering::Unordered);
2635     llvm::Value *ShouldDoInit =
2636         Builder.CreateICmpEQ(SecondGuardLoad, getAllOnesInt());
2637     llvm::BasicBlock *InitBlock = CGF.createBasicBlock("init");
2638     Builder.CreateCondBr(ShouldDoInit, InitBlock, EndBlock);
2639 
2640     // Ok, we ended up getting selected as the initializing thread.
2641     CGF.EmitBlock(InitBlock);
2642     CGF.EHStack.pushCleanup<CallInitThreadAbort>(EHCleanup, GuardAddr);
2643     CGF.EmitCXXGlobalVarDeclInit(D, GV, PerformInit);
2644     CGF.PopCleanupBlock();
2645     CGF.EmitNounwindRuntimeCall(getInitThreadFooterFn(CGM),
2646                                 GuardAddr.getPointer());
2647     Builder.CreateBr(EndBlock);
2648 
2649     CGF.EmitBlock(EndBlock);
2650   }
2651 }
2652 
isZeroInitializable(const MemberPointerType * MPT)2653 bool MicrosoftCXXABI::isZeroInitializable(const MemberPointerType *MPT) {
2654   // Null-ness for function memptrs only depends on the first field, which is
2655   // the function pointer.  The rest don't matter, so we can zero initialize.
2656   if (MPT->isMemberFunctionPointer())
2657     return true;
2658 
2659   // The virtual base adjustment field is always -1 for null, so if we have one
2660   // we can't zero initialize.  The field offset is sometimes also -1 if 0 is a
2661   // valid field offset.
2662   const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();
2663   MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
2664   return (!inheritanceModelHasVBTableOffsetField(Inheritance) &&
2665           RD->nullFieldOffsetIsZero());
2666 }
2667 
2668 llvm::Type *
ConvertMemberPointerType(const MemberPointerType * MPT)2669 MicrosoftCXXABI::ConvertMemberPointerType(const MemberPointerType *MPT) {
2670   const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();
2671   MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
2672   llvm::SmallVector<llvm::Type *, 4> fields;
2673   if (MPT->isMemberFunctionPointer())
2674     fields.push_back(CGM.VoidPtrTy);  // FunctionPointerOrVirtualThunk
2675   else
2676     fields.push_back(CGM.IntTy);  // FieldOffset
2677 
2678   if (inheritanceModelHasNVOffsetField(MPT->isMemberFunctionPointer(),
2679                                        Inheritance))
2680     fields.push_back(CGM.IntTy);
2681   if (inheritanceModelHasVBPtrOffsetField(Inheritance))
2682     fields.push_back(CGM.IntTy);
2683   if (inheritanceModelHasVBTableOffsetField(Inheritance))
2684     fields.push_back(CGM.IntTy);  // VirtualBaseAdjustmentOffset
2685 
2686   if (fields.size() == 1)
2687     return fields[0];
2688   return llvm::StructType::get(CGM.getLLVMContext(), fields);
2689 }
2690 
2691 void MicrosoftCXXABI::
GetNullMemberPointerFields(const MemberPointerType * MPT,llvm::SmallVectorImpl<llvm::Constant * > & fields)2692 GetNullMemberPointerFields(const MemberPointerType *MPT,
2693                            llvm::SmallVectorImpl<llvm::Constant *> &fields) {
2694   assert(fields.empty());
2695   const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();
2696   MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
2697   if (MPT->isMemberFunctionPointer()) {
2698     // FunctionPointerOrVirtualThunk
2699     fields.push_back(llvm::Constant::getNullValue(CGM.VoidPtrTy));
2700   } else {
2701     if (RD->nullFieldOffsetIsZero())
2702       fields.push_back(getZeroInt());  // FieldOffset
2703     else
2704       fields.push_back(getAllOnesInt());  // FieldOffset
2705   }
2706 
2707   if (inheritanceModelHasNVOffsetField(MPT->isMemberFunctionPointer(),
2708                                        Inheritance))
2709     fields.push_back(getZeroInt());
2710   if (inheritanceModelHasVBPtrOffsetField(Inheritance))
2711     fields.push_back(getZeroInt());
2712   if (inheritanceModelHasVBTableOffsetField(Inheritance))
2713     fields.push_back(getAllOnesInt());
2714 }
2715 
2716 llvm::Constant *
EmitNullMemberPointer(const MemberPointerType * MPT)2717 MicrosoftCXXABI::EmitNullMemberPointer(const MemberPointerType *MPT) {
2718   llvm::SmallVector<llvm::Constant *, 4> fields;
2719   GetNullMemberPointerFields(MPT, fields);
2720   if (fields.size() == 1)
2721     return fields[0];
2722   llvm::Constant *Res = llvm::ConstantStruct::getAnon(fields);
2723   assert(Res->getType() == ConvertMemberPointerType(MPT));
2724   return Res;
2725 }
2726 
2727 llvm::Constant *
EmitFullMemberPointer(llvm::Constant * FirstField,bool IsMemberFunction,const CXXRecordDecl * RD,CharUnits NonVirtualBaseAdjustment,unsigned VBTableIndex)2728 MicrosoftCXXABI::EmitFullMemberPointer(llvm::Constant *FirstField,
2729                                        bool IsMemberFunction,
2730                                        const CXXRecordDecl *RD,
2731                                        CharUnits NonVirtualBaseAdjustment,
2732                                        unsigned VBTableIndex) {
2733   MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
2734 
2735   // Single inheritance class member pointer are represented as scalars instead
2736   // of aggregates.
2737   if (inheritanceModelHasOnlyOneField(IsMemberFunction, Inheritance))
2738     return FirstField;
2739 
2740   llvm::SmallVector<llvm::Constant *, 4> fields;
2741   fields.push_back(FirstField);
2742 
2743   if (inheritanceModelHasNVOffsetField(IsMemberFunction, Inheritance))
2744     fields.push_back(llvm::ConstantInt::get(
2745       CGM.IntTy, NonVirtualBaseAdjustment.getQuantity()));
2746 
2747   if (inheritanceModelHasVBPtrOffsetField(Inheritance)) {
2748     CharUnits Offs = CharUnits::Zero();
2749     if (VBTableIndex)
2750       Offs = getContext().getASTRecordLayout(RD).getVBPtrOffset();
2751     fields.push_back(llvm::ConstantInt::get(CGM.IntTy, Offs.getQuantity()));
2752   }
2753 
2754   // The rest of the fields are adjusted by conversions to a more derived class.
2755   if (inheritanceModelHasVBTableOffsetField(Inheritance))
2756     fields.push_back(llvm::ConstantInt::get(CGM.IntTy, VBTableIndex));
2757 
2758   return llvm::ConstantStruct::getAnon(fields);
2759 }
2760 
2761 llvm::Constant *
EmitMemberDataPointer(const MemberPointerType * MPT,CharUnits offset)2762 MicrosoftCXXABI::EmitMemberDataPointer(const MemberPointerType *MPT,
2763                                        CharUnits offset) {
2764   return EmitMemberDataPointer(MPT->getMostRecentCXXRecordDecl(), offset);
2765 }
2766 
EmitMemberDataPointer(const CXXRecordDecl * RD,CharUnits offset)2767 llvm::Constant *MicrosoftCXXABI::EmitMemberDataPointer(const CXXRecordDecl *RD,
2768                                                        CharUnits offset) {
2769   if (RD->getMSInheritanceModel() ==
2770       MSInheritanceModel::Virtual)
2771     offset -= getContext().getOffsetOfBaseWithVBPtr(RD);
2772   llvm::Constant *FirstField =
2773     llvm::ConstantInt::get(CGM.IntTy, offset.getQuantity());
2774   return EmitFullMemberPointer(FirstField, /*IsMemberFunction=*/false, RD,
2775                                CharUnits::Zero(), /*VBTableIndex=*/0);
2776 }
2777 
EmitMemberPointer(const APValue & MP,QualType MPType)2778 llvm::Constant *MicrosoftCXXABI::EmitMemberPointer(const APValue &MP,
2779                                                    QualType MPType) {
2780   const MemberPointerType *DstTy = MPType->castAs<MemberPointerType>();
2781   const ValueDecl *MPD = MP.getMemberPointerDecl();
2782   if (!MPD)
2783     return EmitNullMemberPointer(DstTy);
2784 
2785   ASTContext &Ctx = getContext();
2786   ArrayRef<const CXXRecordDecl *> MemberPointerPath = MP.getMemberPointerPath();
2787 
2788   llvm::Constant *C;
2789   if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(MPD)) {
2790     C = EmitMemberFunctionPointer(MD);
2791   } else {
2792     // For a pointer to data member, start off with the offset of the field in
2793     // the class in which it was declared, and convert from there if necessary.
2794     // For indirect field decls, get the outermost anonymous field and use the
2795     // parent class.
2796     CharUnits FieldOffset = Ctx.toCharUnitsFromBits(Ctx.getFieldOffset(MPD));
2797     const FieldDecl *FD = dyn_cast<FieldDecl>(MPD);
2798     if (!FD)
2799       FD = cast<FieldDecl>(*cast<IndirectFieldDecl>(MPD)->chain_begin());
2800     const CXXRecordDecl *RD = cast<CXXRecordDecl>(FD->getParent());
2801     RD = RD->getMostRecentNonInjectedDecl();
2802     C = EmitMemberDataPointer(RD, FieldOffset);
2803   }
2804 
2805   if (!MemberPointerPath.empty()) {
2806     const CXXRecordDecl *SrcRD = cast<CXXRecordDecl>(MPD->getDeclContext());
2807     const Type *SrcRecTy = Ctx.getTypeDeclType(SrcRD).getTypePtr();
2808     const MemberPointerType *SrcTy =
2809         Ctx.getMemberPointerType(DstTy->getPointeeType(), SrcRecTy)
2810             ->castAs<MemberPointerType>();
2811 
2812     bool DerivedMember = MP.isMemberPointerToDerivedMember();
2813     SmallVector<const CXXBaseSpecifier *, 4> DerivedToBasePath;
2814     const CXXRecordDecl *PrevRD = SrcRD;
2815     for (const CXXRecordDecl *PathElem : MemberPointerPath) {
2816       const CXXRecordDecl *Base = nullptr;
2817       const CXXRecordDecl *Derived = nullptr;
2818       if (DerivedMember) {
2819         Base = PathElem;
2820         Derived = PrevRD;
2821       } else {
2822         Base = PrevRD;
2823         Derived = PathElem;
2824       }
2825       for (const CXXBaseSpecifier &BS : Derived->bases())
2826         if (BS.getType()->getAsCXXRecordDecl()->getCanonicalDecl() ==
2827             Base->getCanonicalDecl())
2828           DerivedToBasePath.push_back(&BS);
2829       PrevRD = PathElem;
2830     }
2831     assert(DerivedToBasePath.size() == MemberPointerPath.size());
2832 
2833     CastKind CK = DerivedMember ? CK_DerivedToBaseMemberPointer
2834                                 : CK_BaseToDerivedMemberPointer;
2835     C = EmitMemberPointerConversion(SrcTy, DstTy, CK, DerivedToBasePath.begin(),
2836                                     DerivedToBasePath.end(), C);
2837   }
2838   return C;
2839 }
2840 
2841 llvm::Constant *
EmitMemberFunctionPointer(const CXXMethodDecl * MD)2842 MicrosoftCXXABI::EmitMemberFunctionPointer(const CXXMethodDecl *MD) {
2843   assert(MD->isInstance() && "Member function must not be static!");
2844 
2845   CharUnits NonVirtualBaseAdjustment = CharUnits::Zero();
2846   const CXXRecordDecl *RD = MD->getParent()->getMostRecentNonInjectedDecl();
2847   CodeGenTypes &Types = CGM.getTypes();
2848 
2849   unsigned VBTableIndex = 0;
2850   llvm::Constant *FirstField;
2851   const FunctionProtoType *FPT = MD->getType()->castAs<FunctionProtoType>();
2852   if (!MD->isVirtual()) {
2853     llvm::Type *Ty;
2854     // Check whether the function has a computable LLVM signature.
2855     if (Types.isFuncTypeConvertible(FPT)) {
2856       // The function has a computable LLVM signature; use the correct type.
2857       Ty = Types.GetFunctionType(Types.arrangeCXXMethodDeclaration(MD));
2858     } else {
2859       // Use an arbitrary non-function type to tell GetAddrOfFunction that the
2860       // function type is incomplete.
2861       Ty = CGM.PtrDiffTy;
2862     }
2863     FirstField = CGM.GetAddrOfFunction(MD, Ty);
2864   } else {
2865     auto &VTableContext = CGM.getMicrosoftVTableContext();
2866     MethodVFTableLocation ML = VTableContext.getMethodVFTableLocation(MD);
2867     FirstField = EmitVirtualMemPtrThunk(MD, ML);
2868     // Include the vfptr adjustment if the method is in a non-primary vftable.
2869     NonVirtualBaseAdjustment += ML.VFPtrOffset;
2870     if (ML.VBase)
2871       VBTableIndex = VTableContext.getVBTableIndex(RD, ML.VBase) * 4;
2872   }
2873 
2874   if (VBTableIndex == 0 &&
2875       RD->getMSInheritanceModel() ==
2876           MSInheritanceModel::Virtual)
2877     NonVirtualBaseAdjustment -= getContext().getOffsetOfBaseWithVBPtr(RD);
2878 
2879   // The rest of the fields are common with data member pointers.
2880   FirstField = llvm::ConstantExpr::getBitCast(FirstField, CGM.VoidPtrTy);
2881   return EmitFullMemberPointer(FirstField, /*IsMemberFunction=*/true, RD,
2882                                NonVirtualBaseAdjustment, VBTableIndex);
2883 }
2884 
2885 /// Member pointers are the same if they're either bitwise identical *or* both
2886 /// null.  Null-ness for function members is determined by the first field,
2887 /// while for data member pointers we must compare all fields.
2888 llvm::Value *
EmitMemberPointerComparison(CodeGenFunction & CGF,llvm::Value * L,llvm::Value * R,const MemberPointerType * MPT,bool Inequality)2889 MicrosoftCXXABI::EmitMemberPointerComparison(CodeGenFunction &CGF,
2890                                              llvm::Value *L,
2891                                              llvm::Value *R,
2892                                              const MemberPointerType *MPT,
2893                                              bool Inequality) {
2894   CGBuilderTy &Builder = CGF.Builder;
2895 
2896   // Handle != comparisons by switching the sense of all boolean operations.
2897   llvm::ICmpInst::Predicate Eq;
2898   llvm::Instruction::BinaryOps And, Or;
2899   if (Inequality) {
2900     Eq = llvm::ICmpInst::ICMP_NE;
2901     And = llvm::Instruction::Or;
2902     Or = llvm::Instruction::And;
2903   } else {
2904     Eq = llvm::ICmpInst::ICMP_EQ;
2905     And = llvm::Instruction::And;
2906     Or = llvm::Instruction::Or;
2907   }
2908 
2909   // If this is a single field member pointer (single inheritance), this is a
2910   // single icmp.
2911   const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();
2912   MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
2913   if (inheritanceModelHasOnlyOneField(MPT->isMemberFunctionPointer(),
2914                                       Inheritance))
2915     return Builder.CreateICmp(Eq, L, R);
2916 
2917   // Compare the first field.
2918   llvm::Value *L0 = Builder.CreateExtractValue(L, 0, "lhs.0");
2919   llvm::Value *R0 = Builder.CreateExtractValue(R, 0, "rhs.0");
2920   llvm::Value *Cmp0 = Builder.CreateICmp(Eq, L0, R0, "memptr.cmp.first");
2921 
2922   // Compare everything other than the first field.
2923   llvm::Value *Res = nullptr;
2924   llvm::StructType *LType = cast<llvm::StructType>(L->getType());
2925   for (unsigned I = 1, E = LType->getNumElements(); I != E; ++I) {
2926     llvm::Value *LF = Builder.CreateExtractValue(L, I);
2927     llvm::Value *RF = Builder.CreateExtractValue(R, I);
2928     llvm::Value *Cmp = Builder.CreateICmp(Eq, LF, RF, "memptr.cmp.rest");
2929     if (Res)
2930       Res = Builder.CreateBinOp(And, Res, Cmp);
2931     else
2932       Res = Cmp;
2933   }
2934 
2935   // Check if the first field is 0 if this is a function pointer.
2936   if (MPT->isMemberFunctionPointer()) {
2937     // (l1 == r1 && ...) || l0 == 0
2938     llvm::Value *Zero = llvm::Constant::getNullValue(L0->getType());
2939     llvm::Value *IsZero = Builder.CreateICmp(Eq, L0, Zero, "memptr.cmp.iszero");
2940     Res = Builder.CreateBinOp(Or, Res, IsZero);
2941   }
2942 
2943   // Combine the comparison of the first field, which must always be true for
2944   // this comparison to succeeed.
2945   return Builder.CreateBinOp(And, Res, Cmp0, "memptr.cmp");
2946 }
2947 
2948 llvm::Value *
EmitMemberPointerIsNotNull(CodeGenFunction & CGF,llvm::Value * MemPtr,const MemberPointerType * MPT)2949 MicrosoftCXXABI::EmitMemberPointerIsNotNull(CodeGenFunction &CGF,
2950                                             llvm::Value *MemPtr,
2951                                             const MemberPointerType *MPT) {
2952   CGBuilderTy &Builder = CGF.Builder;
2953   llvm::SmallVector<llvm::Constant *, 4> fields;
2954   // We only need one field for member functions.
2955   if (MPT->isMemberFunctionPointer())
2956     fields.push_back(llvm::Constant::getNullValue(CGM.VoidPtrTy));
2957   else
2958     GetNullMemberPointerFields(MPT, fields);
2959   assert(!fields.empty());
2960   llvm::Value *FirstField = MemPtr;
2961   if (MemPtr->getType()->isStructTy())
2962     FirstField = Builder.CreateExtractValue(MemPtr, 0);
2963   llvm::Value *Res = Builder.CreateICmpNE(FirstField, fields[0], "memptr.cmp0");
2964 
2965   // For function member pointers, we only need to test the function pointer
2966   // field.  The other fields if any can be garbage.
2967   if (MPT->isMemberFunctionPointer())
2968     return Res;
2969 
2970   // Otherwise, emit a series of compares and combine the results.
2971   for (int I = 1, E = fields.size(); I < E; ++I) {
2972     llvm::Value *Field = Builder.CreateExtractValue(MemPtr, I);
2973     llvm::Value *Next = Builder.CreateICmpNE(Field, fields[I], "memptr.cmp");
2974     Res = Builder.CreateOr(Res, Next, "memptr.tobool");
2975   }
2976   return Res;
2977 }
2978 
MemberPointerConstantIsNull(const MemberPointerType * MPT,llvm::Constant * Val)2979 bool MicrosoftCXXABI::MemberPointerConstantIsNull(const MemberPointerType *MPT,
2980                                                   llvm::Constant *Val) {
2981   // Function pointers are null if the pointer in the first field is null.
2982   if (MPT->isMemberFunctionPointer()) {
2983     llvm::Constant *FirstField = Val->getType()->isStructTy() ?
2984       Val->getAggregateElement(0U) : Val;
2985     return FirstField->isNullValue();
2986   }
2987 
2988   // If it's not a function pointer and it's zero initializable, we can easily
2989   // check zero.
2990   if (isZeroInitializable(MPT) && Val->isNullValue())
2991     return true;
2992 
2993   // Otherwise, break down all the fields for comparison.  Hopefully these
2994   // little Constants are reused, while a big null struct might not be.
2995   llvm::SmallVector<llvm::Constant *, 4> Fields;
2996   GetNullMemberPointerFields(MPT, Fields);
2997   if (Fields.size() == 1) {
2998     assert(Val->getType()->isIntegerTy());
2999     return Val == Fields[0];
3000   }
3001 
3002   unsigned I, E;
3003   for (I = 0, E = Fields.size(); I != E; ++I) {
3004     if (Val->getAggregateElement(I) != Fields[I])
3005       break;
3006   }
3007   return I == E;
3008 }
3009 
3010 llvm::Value *
GetVBaseOffsetFromVBPtr(CodeGenFunction & CGF,Address This,llvm::Value * VBPtrOffset,llvm::Value * VBTableOffset,llvm::Value ** VBPtrOut)3011 MicrosoftCXXABI::GetVBaseOffsetFromVBPtr(CodeGenFunction &CGF,
3012                                          Address This,
3013                                          llvm::Value *VBPtrOffset,
3014                                          llvm::Value *VBTableOffset,
3015                                          llvm::Value **VBPtrOut) {
3016   CGBuilderTy &Builder = CGF.Builder;
3017   // Load the vbtable pointer from the vbptr in the instance.
3018   This = Builder.CreateElementBitCast(This, CGM.Int8Ty);
3019   llvm::Value *VBPtr = Builder.CreateInBoundsGEP(
3020       This.getElementType(), This.getPointer(), VBPtrOffset, "vbptr");
3021   if (VBPtrOut) *VBPtrOut = VBPtr;
3022   VBPtr = Builder.CreateBitCast(VBPtr,
3023             CGM.Int32Ty->getPointerTo(0)->getPointerTo(This.getAddressSpace()));
3024 
3025   CharUnits VBPtrAlign;
3026   if (auto CI = dyn_cast<llvm::ConstantInt>(VBPtrOffset)) {
3027     VBPtrAlign = This.getAlignment().alignmentAtOffset(
3028                                    CharUnits::fromQuantity(CI->getSExtValue()));
3029   } else {
3030     VBPtrAlign = CGF.getPointerAlign();
3031   }
3032 
3033   llvm::Value *VBTable = Builder.CreateAlignedLoad(
3034       CGM.Int32Ty->getPointerTo(0), VBPtr, VBPtrAlign, "vbtable");
3035 
3036   // Translate from byte offset to table index. It improves analyzability.
3037   llvm::Value *VBTableIndex = Builder.CreateAShr(
3038       VBTableOffset, llvm::ConstantInt::get(VBTableOffset->getType(), 2),
3039       "vbtindex", /*isExact=*/true);
3040 
3041   // Load an i32 offset from the vb-table.
3042   llvm::Value *VBaseOffs =
3043       Builder.CreateInBoundsGEP(CGM.Int32Ty, VBTable, VBTableIndex);
3044   VBaseOffs = Builder.CreateBitCast(VBaseOffs, CGM.Int32Ty->getPointerTo(0));
3045   return Builder.CreateAlignedLoad(CGM.Int32Ty, VBaseOffs,
3046                                    CharUnits::fromQuantity(4), "vbase_offs");
3047 }
3048 
3049 // Returns an adjusted base cast to i8*, since we do more address arithmetic on
3050 // it.
AdjustVirtualBase(CodeGenFunction & CGF,const Expr * E,const CXXRecordDecl * RD,Address Base,llvm::Value * VBTableOffset,llvm::Value * VBPtrOffset)3051 llvm::Value *MicrosoftCXXABI::AdjustVirtualBase(
3052     CodeGenFunction &CGF, const Expr *E, const CXXRecordDecl *RD,
3053     Address Base, llvm::Value *VBTableOffset, llvm::Value *VBPtrOffset) {
3054   CGBuilderTy &Builder = CGF.Builder;
3055   Base = Builder.CreateElementBitCast(Base, CGM.Int8Ty);
3056   llvm::BasicBlock *OriginalBB = nullptr;
3057   llvm::BasicBlock *SkipAdjustBB = nullptr;
3058   llvm::BasicBlock *VBaseAdjustBB = nullptr;
3059 
3060   // In the unspecified inheritance model, there might not be a vbtable at all,
3061   // in which case we need to skip the virtual base lookup.  If there is a
3062   // vbtable, the first entry is a no-op entry that gives back the original
3063   // base, so look for a virtual base adjustment offset of zero.
3064   if (VBPtrOffset) {
3065     OriginalBB = Builder.GetInsertBlock();
3066     VBaseAdjustBB = CGF.createBasicBlock("memptr.vadjust");
3067     SkipAdjustBB = CGF.createBasicBlock("memptr.skip_vadjust");
3068     llvm::Value *IsVirtual =
3069       Builder.CreateICmpNE(VBTableOffset, getZeroInt(),
3070                            "memptr.is_vbase");
3071     Builder.CreateCondBr(IsVirtual, VBaseAdjustBB, SkipAdjustBB);
3072     CGF.EmitBlock(VBaseAdjustBB);
3073   }
3074 
3075   // If we weren't given a dynamic vbptr offset, RD should be complete and we'll
3076   // know the vbptr offset.
3077   if (!VBPtrOffset) {
3078     CharUnits offs = CharUnits::Zero();
3079     if (!RD->hasDefinition()) {
3080       DiagnosticsEngine &Diags = CGF.CGM.getDiags();
3081       unsigned DiagID = Diags.getCustomDiagID(
3082           DiagnosticsEngine::Error,
3083           "member pointer representation requires a "
3084           "complete class type for %0 to perform this expression");
3085       Diags.Report(E->getExprLoc(), DiagID) << RD << E->getSourceRange();
3086     } else if (RD->getNumVBases())
3087       offs = getContext().getASTRecordLayout(RD).getVBPtrOffset();
3088     VBPtrOffset = llvm::ConstantInt::get(CGM.IntTy, offs.getQuantity());
3089   }
3090   llvm::Value *VBPtr = nullptr;
3091   llvm::Value *VBaseOffs =
3092     GetVBaseOffsetFromVBPtr(CGF, Base, VBPtrOffset, VBTableOffset, &VBPtr);
3093   llvm::Value *AdjustedBase =
3094     Builder.CreateInBoundsGEP(CGM.Int8Ty, VBPtr, VBaseOffs);
3095 
3096   // Merge control flow with the case where we didn't have to adjust.
3097   if (VBaseAdjustBB) {
3098     Builder.CreateBr(SkipAdjustBB);
3099     CGF.EmitBlock(SkipAdjustBB);
3100     llvm::PHINode *Phi = Builder.CreatePHI(CGM.Int8PtrTy, 2, "memptr.base");
3101     Phi->addIncoming(Base.getPointer(), OriginalBB);
3102     Phi->addIncoming(AdjustedBase, VBaseAdjustBB);
3103     return Phi;
3104   }
3105   return AdjustedBase;
3106 }
3107 
EmitMemberDataPointerAddress(CodeGenFunction & CGF,const Expr * E,Address Base,llvm::Value * MemPtr,const MemberPointerType * MPT)3108 llvm::Value *MicrosoftCXXABI::EmitMemberDataPointerAddress(
3109     CodeGenFunction &CGF, const Expr *E, Address Base, llvm::Value *MemPtr,
3110     const MemberPointerType *MPT) {
3111   assert(MPT->isMemberDataPointer());
3112   unsigned AS = Base.getAddressSpace();
3113   llvm::Type *PType =
3114       CGF.ConvertTypeForMem(MPT->getPointeeType())->getPointerTo(AS);
3115   CGBuilderTy &Builder = CGF.Builder;
3116   const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();
3117   MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
3118 
3119   // Extract the fields we need, regardless of model.  We'll apply them if we
3120   // have them.
3121   llvm::Value *FieldOffset = MemPtr;
3122   llvm::Value *VirtualBaseAdjustmentOffset = nullptr;
3123   llvm::Value *VBPtrOffset = nullptr;
3124   if (MemPtr->getType()->isStructTy()) {
3125     // We need to extract values.
3126     unsigned I = 0;
3127     FieldOffset = Builder.CreateExtractValue(MemPtr, I++);
3128     if (inheritanceModelHasVBPtrOffsetField(Inheritance))
3129       VBPtrOffset = Builder.CreateExtractValue(MemPtr, I++);
3130     if (inheritanceModelHasVBTableOffsetField(Inheritance))
3131       VirtualBaseAdjustmentOffset = Builder.CreateExtractValue(MemPtr, I++);
3132   }
3133 
3134   llvm::Value *Addr;
3135   if (VirtualBaseAdjustmentOffset) {
3136     Addr = AdjustVirtualBase(CGF, E, RD, Base, VirtualBaseAdjustmentOffset,
3137                              VBPtrOffset);
3138   } else {
3139     Addr = Base.getPointer();
3140   }
3141 
3142   // Cast to char*.
3143   Addr = Builder.CreateBitCast(Addr, CGF.Int8Ty->getPointerTo(AS));
3144 
3145   // Apply the offset, which we assume is non-null.
3146   Addr = Builder.CreateInBoundsGEP(CGF.Int8Ty, Addr, FieldOffset,
3147                                    "memptr.offset");
3148 
3149   // Cast the address to the appropriate pointer type, adopting the address
3150   // space of the base pointer.
3151   return Builder.CreateBitCast(Addr, PType);
3152 }
3153 
3154 llvm::Value *
EmitMemberPointerConversion(CodeGenFunction & CGF,const CastExpr * E,llvm::Value * Src)3155 MicrosoftCXXABI::EmitMemberPointerConversion(CodeGenFunction &CGF,
3156                                              const CastExpr *E,
3157                                              llvm::Value *Src) {
3158   assert(E->getCastKind() == CK_DerivedToBaseMemberPointer ||
3159          E->getCastKind() == CK_BaseToDerivedMemberPointer ||
3160          E->getCastKind() == CK_ReinterpretMemberPointer);
3161 
3162   // Use constant emission if we can.
3163   if (isa<llvm::Constant>(Src))
3164     return EmitMemberPointerConversion(E, cast<llvm::Constant>(Src));
3165 
3166   // We may be adding or dropping fields from the member pointer, so we need
3167   // both types and the inheritance models of both records.
3168   const MemberPointerType *SrcTy =
3169     E->getSubExpr()->getType()->castAs<MemberPointerType>();
3170   const MemberPointerType *DstTy = E->getType()->castAs<MemberPointerType>();
3171   bool IsFunc = SrcTy->isMemberFunctionPointer();
3172 
3173   // If the classes use the same null representation, reinterpret_cast is a nop.
3174   bool IsReinterpret = E->getCastKind() == CK_ReinterpretMemberPointer;
3175   if (IsReinterpret && IsFunc)
3176     return Src;
3177 
3178   CXXRecordDecl *SrcRD = SrcTy->getMostRecentCXXRecordDecl();
3179   CXXRecordDecl *DstRD = DstTy->getMostRecentCXXRecordDecl();
3180   if (IsReinterpret &&
3181       SrcRD->nullFieldOffsetIsZero() == DstRD->nullFieldOffsetIsZero())
3182     return Src;
3183 
3184   CGBuilderTy &Builder = CGF.Builder;
3185 
3186   // Branch past the conversion if Src is null.
3187   llvm::Value *IsNotNull = EmitMemberPointerIsNotNull(CGF, Src, SrcTy);
3188   llvm::Constant *DstNull = EmitNullMemberPointer(DstTy);
3189 
3190   // C++ 5.2.10p9: The null member pointer value is converted to the null member
3191   //   pointer value of the destination type.
3192   if (IsReinterpret) {
3193     // For reinterpret casts, sema ensures that src and dst are both functions
3194     // or data and have the same size, which means the LLVM types should match.
3195     assert(Src->getType() == DstNull->getType());
3196     return Builder.CreateSelect(IsNotNull, Src, DstNull);
3197   }
3198 
3199   llvm::BasicBlock *OriginalBB = Builder.GetInsertBlock();
3200   llvm::BasicBlock *ConvertBB = CGF.createBasicBlock("memptr.convert");
3201   llvm::BasicBlock *ContinueBB = CGF.createBasicBlock("memptr.converted");
3202   Builder.CreateCondBr(IsNotNull, ConvertBB, ContinueBB);
3203   CGF.EmitBlock(ConvertBB);
3204 
3205   llvm::Value *Dst = EmitNonNullMemberPointerConversion(
3206       SrcTy, DstTy, E->getCastKind(), E->path_begin(), E->path_end(), Src,
3207       Builder);
3208 
3209   Builder.CreateBr(ContinueBB);
3210 
3211   // In the continuation, choose between DstNull and Dst.
3212   CGF.EmitBlock(ContinueBB);
3213   llvm::PHINode *Phi = Builder.CreatePHI(DstNull->getType(), 2, "memptr.converted");
3214   Phi->addIncoming(DstNull, OriginalBB);
3215   Phi->addIncoming(Dst, ConvertBB);
3216   return Phi;
3217 }
3218 
EmitNonNullMemberPointerConversion(const MemberPointerType * SrcTy,const MemberPointerType * DstTy,CastKind CK,CastExpr::path_const_iterator PathBegin,CastExpr::path_const_iterator PathEnd,llvm::Value * Src,CGBuilderTy & Builder)3219 llvm::Value *MicrosoftCXXABI::EmitNonNullMemberPointerConversion(
3220     const MemberPointerType *SrcTy, const MemberPointerType *DstTy, CastKind CK,
3221     CastExpr::path_const_iterator PathBegin,
3222     CastExpr::path_const_iterator PathEnd, llvm::Value *Src,
3223     CGBuilderTy &Builder) {
3224   const CXXRecordDecl *SrcRD = SrcTy->getMostRecentCXXRecordDecl();
3225   const CXXRecordDecl *DstRD = DstTy->getMostRecentCXXRecordDecl();
3226   MSInheritanceModel SrcInheritance = SrcRD->getMSInheritanceModel();
3227   MSInheritanceModel DstInheritance = DstRD->getMSInheritanceModel();
3228   bool IsFunc = SrcTy->isMemberFunctionPointer();
3229   bool IsConstant = isa<llvm::Constant>(Src);
3230 
3231   // Decompose src.
3232   llvm::Value *FirstField = Src;
3233   llvm::Value *NonVirtualBaseAdjustment = getZeroInt();
3234   llvm::Value *VirtualBaseAdjustmentOffset = getZeroInt();
3235   llvm::Value *VBPtrOffset = getZeroInt();
3236   if (!inheritanceModelHasOnlyOneField(IsFunc, SrcInheritance)) {
3237     // We need to extract values.
3238     unsigned I = 0;
3239     FirstField = Builder.CreateExtractValue(Src, I++);
3240     if (inheritanceModelHasNVOffsetField(IsFunc, SrcInheritance))
3241       NonVirtualBaseAdjustment = Builder.CreateExtractValue(Src, I++);
3242     if (inheritanceModelHasVBPtrOffsetField(SrcInheritance))
3243       VBPtrOffset = Builder.CreateExtractValue(Src, I++);
3244     if (inheritanceModelHasVBTableOffsetField(SrcInheritance))
3245       VirtualBaseAdjustmentOffset = Builder.CreateExtractValue(Src, I++);
3246   }
3247 
3248   bool IsDerivedToBase = (CK == CK_DerivedToBaseMemberPointer);
3249   const MemberPointerType *DerivedTy = IsDerivedToBase ? SrcTy : DstTy;
3250   const CXXRecordDecl *DerivedClass = DerivedTy->getMostRecentCXXRecordDecl();
3251 
3252   // For data pointers, we adjust the field offset directly.  For functions, we
3253   // have a separate field.
3254   llvm::Value *&NVAdjustField = IsFunc ? NonVirtualBaseAdjustment : FirstField;
3255 
3256   // The virtual inheritance model has a quirk: the virtual base table is always
3257   // referenced when dereferencing a member pointer even if the member pointer
3258   // is non-virtual.  This is accounted for by adjusting the non-virtual offset
3259   // to point backwards to the top of the MDC from the first VBase.  Undo this
3260   // adjustment to normalize the member pointer.
3261   llvm::Value *SrcVBIndexEqZero =
3262       Builder.CreateICmpEQ(VirtualBaseAdjustmentOffset, getZeroInt());
3263   if (SrcInheritance == MSInheritanceModel::Virtual) {
3264     if (int64_t SrcOffsetToFirstVBase =
3265             getContext().getOffsetOfBaseWithVBPtr(SrcRD).getQuantity()) {
3266       llvm::Value *UndoSrcAdjustment = Builder.CreateSelect(
3267           SrcVBIndexEqZero,
3268           llvm::ConstantInt::get(CGM.IntTy, SrcOffsetToFirstVBase),
3269           getZeroInt());
3270       NVAdjustField = Builder.CreateNSWAdd(NVAdjustField, UndoSrcAdjustment);
3271     }
3272   }
3273 
3274   // A non-zero vbindex implies that we are dealing with a source member in a
3275   // floating virtual base in addition to some non-virtual offset.  If the
3276   // vbindex is zero, we are dealing with a source that exists in a non-virtual,
3277   // fixed, base.  The difference between these two cases is that the vbindex +
3278   // nvoffset *always* point to the member regardless of what context they are
3279   // evaluated in so long as the vbindex is adjusted.  A member inside a fixed
3280   // base requires explicit nv adjustment.
3281   llvm::Constant *BaseClassOffset = llvm::ConstantInt::get(
3282       CGM.IntTy,
3283       CGM.computeNonVirtualBaseClassOffset(DerivedClass, PathBegin, PathEnd)
3284           .getQuantity());
3285 
3286   llvm::Value *NVDisp;
3287   if (IsDerivedToBase)
3288     NVDisp = Builder.CreateNSWSub(NVAdjustField, BaseClassOffset, "adj");
3289   else
3290     NVDisp = Builder.CreateNSWAdd(NVAdjustField, BaseClassOffset, "adj");
3291 
3292   NVAdjustField = Builder.CreateSelect(SrcVBIndexEqZero, NVDisp, getZeroInt());
3293 
3294   // Update the vbindex to an appropriate value in the destination because
3295   // SrcRD's vbtable might not be a strict prefix of the one in DstRD.
3296   llvm::Value *DstVBIndexEqZero = SrcVBIndexEqZero;
3297   if (inheritanceModelHasVBTableOffsetField(DstInheritance) &&
3298       inheritanceModelHasVBTableOffsetField(SrcInheritance)) {
3299     if (llvm::GlobalVariable *VDispMap =
3300             getAddrOfVirtualDisplacementMap(SrcRD, DstRD)) {
3301       llvm::Value *VBIndex = Builder.CreateExactUDiv(
3302           VirtualBaseAdjustmentOffset, llvm::ConstantInt::get(CGM.IntTy, 4));
3303       if (IsConstant) {
3304         llvm::Constant *Mapping = VDispMap->getInitializer();
3305         VirtualBaseAdjustmentOffset =
3306             Mapping->getAggregateElement(cast<llvm::Constant>(VBIndex));
3307       } else {
3308         llvm::Value *Idxs[] = {getZeroInt(), VBIndex};
3309         VirtualBaseAdjustmentOffset = Builder.CreateAlignedLoad(
3310             CGM.IntTy, Builder.CreateInBoundsGEP(VDispMap->getValueType(),
3311                                                  VDispMap, Idxs),
3312             CharUnits::fromQuantity(4));
3313       }
3314 
3315       DstVBIndexEqZero =
3316           Builder.CreateICmpEQ(VirtualBaseAdjustmentOffset, getZeroInt());
3317     }
3318   }
3319 
3320   // Set the VBPtrOffset to zero if the vbindex is zero.  Otherwise, initialize
3321   // it to the offset of the vbptr.
3322   if (inheritanceModelHasVBPtrOffsetField(DstInheritance)) {
3323     llvm::Value *DstVBPtrOffset = llvm::ConstantInt::get(
3324         CGM.IntTy,
3325         getContext().getASTRecordLayout(DstRD).getVBPtrOffset().getQuantity());
3326     VBPtrOffset =
3327         Builder.CreateSelect(DstVBIndexEqZero, getZeroInt(), DstVBPtrOffset);
3328   }
3329 
3330   // Likewise, apply a similar adjustment so that dereferencing the member
3331   // pointer correctly accounts for the distance between the start of the first
3332   // virtual base and the top of the MDC.
3333   if (DstInheritance == MSInheritanceModel::Virtual) {
3334     if (int64_t DstOffsetToFirstVBase =
3335             getContext().getOffsetOfBaseWithVBPtr(DstRD).getQuantity()) {
3336       llvm::Value *DoDstAdjustment = Builder.CreateSelect(
3337           DstVBIndexEqZero,
3338           llvm::ConstantInt::get(CGM.IntTy, DstOffsetToFirstVBase),
3339           getZeroInt());
3340       NVAdjustField = Builder.CreateNSWSub(NVAdjustField, DoDstAdjustment);
3341     }
3342   }
3343 
3344   // Recompose dst from the null struct and the adjusted fields from src.
3345   llvm::Value *Dst;
3346   if (inheritanceModelHasOnlyOneField(IsFunc, DstInheritance)) {
3347     Dst = FirstField;
3348   } else {
3349     Dst = llvm::UndefValue::get(ConvertMemberPointerType(DstTy));
3350     unsigned Idx = 0;
3351     Dst = Builder.CreateInsertValue(Dst, FirstField, Idx++);
3352     if (inheritanceModelHasNVOffsetField(IsFunc, DstInheritance))
3353       Dst = Builder.CreateInsertValue(Dst, NonVirtualBaseAdjustment, Idx++);
3354     if (inheritanceModelHasVBPtrOffsetField(DstInheritance))
3355       Dst = Builder.CreateInsertValue(Dst, VBPtrOffset, Idx++);
3356     if (inheritanceModelHasVBTableOffsetField(DstInheritance))
3357       Dst = Builder.CreateInsertValue(Dst, VirtualBaseAdjustmentOffset, Idx++);
3358   }
3359   return Dst;
3360 }
3361 
3362 llvm::Constant *
EmitMemberPointerConversion(const CastExpr * E,llvm::Constant * Src)3363 MicrosoftCXXABI::EmitMemberPointerConversion(const CastExpr *E,
3364                                              llvm::Constant *Src) {
3365   const MemberPointerType *SrcTy =
3366       E->getSubExpr()->getType()->castAs<MemberPointerType>();
3367   const MemberPointerType *DstTy = E->getType()->castAs<MemberPointerType>();
3368 
3369   CastKind CK = E->getCastKind();
3370 
3371   return EmitMemberPointerConversion(SrcTy, DstTy, CK, E->path_begin(),
3372                                      E->path_end(), Src);
3373 }
3374 
EmitMemberPointerConversion(const MemberPointerType * SrcTy,const MemberPointerType * DstTy,CastKind CK,CastExpr::path_const_iterator PathBegin,CastExpr::path_const_iterator PathEnd,llvm::Constant * Src)3375 llvm::Constant *MicrosoftCXXABI::EmitMemberPointerConversion(
3376     const MemberPointerType *SrcTy, const MemberPointerType *DstTy, CastKind CK,
3377     CastExpr::path_const_iterator PathBegin,
3378     CastExpr::path_const_iterator PathEnd, llvm::Constant *Src) {
3379   assert(CK == CK_DerivedToBaseMemberPointer ||
3380          CK == CK_BaseToDerivedMemberPointer ||
3381          CK == CK_ReinterpretMemberPointer);
3382   // If src is null, emit a new null for dst.  We can't return src because dst
3383   // might have a new representation.
3384   if (MemberPointerConstantIsNull(SrcTy, Src))
3385     return EmitNullMemberPointer(DstTy);
3386 
3387   // We don't need to do anything for reinterpret_casts of non-null member
3388   // pointers.  We should only get here when the two type representations have
3389   // the same size.
3390   if (CK == CK_ReinterpretMemberPointer)
3391     return Src;
3392 
3393   CGBuilderTy Builder(CGM, CGM.getLLVMContext());
3394   auto *Dst = cast<llvm::Constant>(EmitNonNullMemberPointerConversion(
3395       SrcTy, DstTy, CK, PathBegin, PathEnd, Src, Builder));
3396 
3397   return Dst;
3398 }
3399 
EmitLoadOfMemberFunctionPointer(CodeGenFunction & CGF,const Expr * E,Address This,llvm::Value * & ThisPtrForCall,llvm::Value * MemPtr,const MemberPointerType * MPT)3400 CGCallee MicrosoftCXXABI::EmitLoadOfMemberFunctionPointer(
3401     CodeGenFunction &CGF, const Expr *E, Address This,
3402     llvm::Value *&ThisPtrForCall, llvm::Value *MemPtr,
3403     const MemberPointerType *MPT) {
3404   assert(MPT->isMemberFunctionPointer());
3405   const FunctionProtoType *FPT =
3406     MPT->getPointeeType()->castAs<FunctionProtoType>();
3407   const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();
3408   llvm::FunctionType *FTy = CGM.getTypes().GetFunctionType(
3409       CGM.getTypes().arrangeCXXMethodType(RD, FPT, /*FD=*/nullptr));
3410   CGBuilderTy &Builder = CGF.Builder;
3411 
3412   MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
3413 
3414   // Extract the fields we need, regardless of model.  We'll apply them if we
3415   // have them.
3416   llvm::Value *FunctionPointer = MemPtr;
3417   llvm::Value *NonVirtualBaseAdjustment = nullptr;
3418   llvm::Value *VirtualBaseAdjustmentOffset = nullptr;
3419   llvm::Value *VBPtrOffset = nullptr;
3420   if (MemPtr->getType()->isStructTy()) {
3421     // We need to extract values.
3422     unsigned I = 0;
3423     FunctionPointer = Builder.CreateExtractValue(MemPtr, I++);
3424     if (inheritanceModelHasNVOffsetField(MPT, Inheritance))
3425       NonVirtualBaseAdjustment = Builder.CreateExtractValue(MemPtr, I++);
3426     if (inheritanceModelHasVBPtrOffsetField(Inheritance))
3427       VBPtrOffset = Builder.CreateExtractValue(MemPtr, I++);
3428     if (inheritanceModelHasVBTableOffsetField(Inheritance))
3429       VirtualBaseAdjustmentOffset = Builder.CreateExtractValue(MemPtr, I++);
3430   }
3431 
3432   if (VirtualBaseAdjustmentOffset) {
3433     ThisPtrForCall = AdjustVirtualBase(CGF, E, RD, This,
3434                                    VirtualBaseAdjustmentOffset, VBPtrOffset);
3435   } else {
3436     ThisPtrForCall = This.getPointer();
3437   }
3438 
3439   if (NonVirtualBaseAdjustment) {
3440     // Apply the adjustment and cast back to the original struct type.
3441     llvm::Value *Ptr = Builder.CreateBitCast(ThisPtrForCall, CGF.Int8PtrTy);
3442     Ptr = Builder.CreateInBoundsGEP(CGF.Int8Ty, Ptr, NonVirtualBaseAdjustment);
3443     ThisPtrForCall = Builder.CreateBitCast(Ptr, ThisPtrForCall->getType(),
3444                                            "this.adjusted");
3445   }
3446 
3447   FunctionPointer =
3448     Builder.CreateBitCast(FunctionPointer, FTy->getPointerTo());
3449   CGCallee Callee(FPT, FunctionPointer);
3450   return Callee;
3451 }
3452 
CreateMicrosoftCXXABI(CodeGenModule & CGM)3453 CGCXXABI *clang::CodeGen::CreateMicrosoftCXXABI(CodeGenModule &CGM) {
3454   return new MicrosoftCXXABI(CGM);
3455 }
3456 
3457 // MS RTTI Overview:
3458 // The run time type information emitted by cl.exe contains 5 distinct types of
3459 // structures.  Many of them reference each other.
3460 //
3461 // TypeInfo:  Static classes that are returned by typeid.
3462 //
3463 // CompleteObjectLocator:  Referenced by vftables.  They contain information
3464 //   required for dynamic casting, including OffsetFromTop.  They also contain
3465 //   a reference to the TypeInfo for the type and a reference to the
3466 //   CompleteHierarchyDescriptor for the type.
3467 //
3468 // ClassHierarchyDescriptor: Contains information about a class hierarchy.
3469 //   Used during dynamic_cast to walk a class hierarchy.  References a base
3470 //   class array and the size of said array.
3471 //
3472 // BaseClassArray: Contains a list of classes in a hierarchy.  BaseClassArray is
3473 //   somewhat of a misnomer because the most derived class is also in the list
3474 //   as well as multiple copies of virtual bases (if they occur multiple times
3475 //   in the hierarchy.)  The BaseClassArray contains one BaseClassDescriptor for
3476 //   every path in the hierarchy, in pre-order depth first order.  Note, we do
3477 //   not declare a specific llvm type for BaseClassArray, it's merely an array
3478 //   of BaseClassDescriptor pointers.
3479 //
3480 // BaseClassDescriptor: Contains information about a class in a class hierarchy.
3481 //   BaseClassDescriptor is also somewhat of a misnomer for the same reason that
3482 //   BaseClassArray is.  It contains information about a class within a
3483 //   hierarchy such as: is this base is ambiguous and what is its offset in the
3484 //   vbtable.  The names of the BaseClassDescriptors have all of their fields
3485 //   mangled into them so they can be aggressively deduplicated by the linker.
3486 
getTypeInfoVTable(CodeGenModule & CGM)3487 static llvm::GlobalVariable *getTypeInfoVTable(CodeGenModule &CGM) {
3488   StringRef MangledName("??_7type_info@@6B@");
3489   if (auto VTable = CGM.getModule().getNamedGlobal(MangledName))
3490     return VTable;
3491   return new llvm::GlobalVariable(CGM.getModule(), CGM.Int8PtrTy,
3492                                   /*isConstant=*/true,
3493                                   llvm::GlobalVariable::ExternalLinkage,
3494                                   /*Initializer=*/nullptr, MangledName);
3495 }
3496 
3497 namespace {
3498 
3499 /// A Helper struct that stores information about a class in a class
3500 /// hierarchy.  The information stored in these structs struct is used during
3501 /// the generation of ClassHierarchyDescriptors and BaseClassDescriptors.
3502 // During RTTI creation, MSRTTIClasses are stored in a contiguous array with
3503 // implicit depth first pre-order tree connectivity.  getFirstChild and
3504 // getNextSibling allow us to walk the tree efficiently.
3505 struct MSRTTIClass {
3506   enum {
3507     IsPrivateOnPath = 1 | 8,
3508     IsAmbiguous = 2,
3509     IsPrivate = 4,
3510     IsVirtual = 16,
3511     HasHierarchyDescriptor = 64
3512   };
MSRTTIClass__anona6ec54210811::MSRTTIClass3513   MSRTTIClass(const CXXRecordDecl *RD) : RD(RD) {}
3514   uint32_t initialize(const MSRTTIClass *Parent,
3515                       const CXXBaseSpecifier *Specifier);
3516 
getFirstChild__anona6ec54210811::MSRTTIClass3517   MSRTTIClass *getFirstChild() { return this + 1; }
getNextChild__anona6ec54210811::MSRTTIClass3518   static MSRTTIClass *getNextChild(MSRTTIClass *Child) {
3519     return Child + 1 + Child->NumBases;
3520   }
3521 
3522   const CXXRecordDecl *RD, *VirtualRoot;
3523   uint32_t Flags, NumBases, OffsetInVBase;
3524 };
3525 
3526 /// Recursively initialize the base class array.
initialize(const MSRTTIClass * Parent,const CXXBaseSpecifier * Specifier)3527 uint32_t MSRTTIClass::initialize(const MSRTTIClass *Parent,
3528                                  const CXXBaseSpecifier *Specifier) {
3529   Flags = HasHierarchyDescriptor;
3530   if (!Parent) {
3531     VirtualRoot = nullptr;
3532     OffsetInVBase = 0;
3533   } else {
3534     if (Specifier->getAccessSpecifier() != AS_public)
3535       Flags |= IsPrivate | IsPrivateOnPath;
3536     if (Specifier->isVirtual()) {
3537       Flags |= IsVirtual;
3538       VirtualRoot = RD;
3539       OffsetInVBase = 0;
3540     } else {
3541       if (Parent->Flags & IsPrivateOnPath)
3542         Flags |= IsPrivateOnPath;
3543       VirtualRoot = Parent->VirtualRoot;
3544       OffsetInVBase = Parent->OffsetInVBase + RD->getASTContext()
3545           .getASTRecordLayout(Parent->RD).getBaseClassOffset(RD).getQuantity();
3546     }
3547   }
3548   NumBases = 0;
3549   MSRTTIClass *Child = getFirstChild();
3550   for (const CXXBaseSpecifier &Base : RD->bases()) {
3551     NumBases += Child->initialize(this, &Base) + 1;
3552     Child = getNextChild(Child);
3553   }
3554   return NumBases;
3555 }
3556 
getLinkageForRTTI(QualType Ty)3557 static llvm::GlobalValue::LinkageTypes getLinkageForRTTI(QualType Ty) {
3558   switch (Ty->getLinkage()) {
3559   case NoLinkage:
3560   case InternalLinkage:
3561   case UniqueExternalLinkage:
3562     return llvm::GlobalValue::InternalLinkage;
3563 
3564   case VisibleNoLinkage:
3565   case ModuleInternalLinkage:
3566   case ModuleLinkage:
3567   case ExternalLinkage:
3568     return llvm::GlobalValue::LinkOnceODRLinkage;
3569   }
3570   llvm_unreachable("Invalid linkage!");
3571 }
3572 
3573 /// An ephemeral helper class for building MS RTTI types.  It caches some
3574 /// calls to the module and information about the most derived class in a
3575 /// hierarchy.
3576 struct MSRTTIBuilder {
3577   enum {
3578     HasBranchingHierarchy = 1,
3579     HasVirtualBranchingHierarchy = 2,
3580     HasAmbiguousBases = 4
3581   };
3582 
MSRTTIBuilder__anona6ec54210811::MSRTTIBuilder3583   MSRTTIBuilder(MicrosoftCXXABI &ABI, const CXXRecordDecl *RD)
3584       : CGM(ABI.CGM), Context(CGM.getContext()),
3585         VMContext(CGM.getLLVMContext()), Module(CGM.getModule()), RD(RD),
3586         Linkage(getLinkageForRTTI(CGM.getContext().getTagDeclType(RD))),
3587         ABI(ABI) {}
3588 
3589   llvm::GlobalVariable *getBaseClassDescriptor(const MSRTTIClass &Classes);
3590   llvm::GlobalVariable *
3591   getBaseClassArray(SmallVectorImpl<MSRTTIClass> &Classes);
3592   llvm::GlobalVariable *getClassHierarchyDescriptor();
3593   llvm::GlobalVariable *getCompleteObjectLocator(const VPtrInfo &Info);
3594 
3595   CodeGenModule &CGM;
3596   ASTContext &Context;
3597   llvm::LLVMContext &VMContext;
3598   llvm::Module &Module;
3599   const CXXRecordDecl *RD;
3600   llvm::GlobalVariable::LinkageTypes Linkage;
3601   MicrosoftCXXABI &ABI;
3602 };
3603 
3604 } // namespace
3605 
3606 /// Recursively serializes a class hierarchy in pre-order depth first
3607 /// order.
serializeClassHierarchy(SmallVectorImpl<MSRTTIClass> & Classes,const CXXRecordDecl * RD)3608 static void serializeClassHierarchy(SmallVectorImpl<MSRTTIClass> &Classes,
3609                                     const CXXRecordDecl *RD) {
3610   Classes.push_back(MSRTTIClass(RD));
3611   for (const CXXBaseSpecifier &Base : RD->bases())
3612     serializeClassHierarchy(Classes, Base.getType()->getAsCXXRecordDecl());
3613 }
3614 
3615 /// Find ambiguity among base classes.
3616 static void
detectAmbiguousBases(SmallVectorImpl<MSRTTIClass> & Classes)3617 detectAmbiguousBases(SmallVectorImpl<MSRTTIClass> &Classes) {
3618   llvm::SmallPtrSet<const CXXRecordDecl *, 8> VirtualBases;
3619   llvm::SmallPtrSet<const CXXRecordDecl *, 8> UniqueBases;
3620   llvm::SmallPtrSet<const CXXRecordDecl *, 8> AmbiguousBases;
3621   for (MSRTTIClass *Class = &Classes.front(); Class <= &Classes.back();) {
3622     if ((Class->Flags & MSRTTIClass::IsVirtual) &&
3623         !VirtualBases.insert(Class->RD).second) {
3624       Class = MSRTTIClass::getNextChild(Class);
3625       continue;
3626     }
3627     if (!UniqueBases.insert(Class->RD).second)
3628       AmbiguousBases.insert(Class->RD);
3629     Class++;
3630   }
3631   if (AmbiguousBases.empty())
3632     return;
3633   for (MSRTTIClass &Class : Classes)
3634     if (AmbiguousBases.count(Class.RD))
3635       Class.Flags |= MSRTTIClass::IsAmbiguous;
3636 }
3637 
getClassHierarchyDescriptor()3638 llvm::GlobalVariable *MSRTTIBuilder::getClassHierarchyDescriptor() {
3639   SmallString<256> MangledName;
3640   {
3641     llvm::raw_svector_ostream Out(MangledName);
3642     ABI.getMangleContext().mangleCXXRTTIClassHierarchyDescriptor(RD, Out);
3643   }
3644 
3645   // Check to see if we've already declared this ClassHierarchyDescriptor.
3646   if (auto CHD = Module.getNamedGlobal(MangledName))
3647     return CHD;
3648 
3649   // Serialize the class hierarchy and initialize the CHD Fields.
3650   SmallVector<MSRTTIClass, 8> Classes;
3651   serializeClassHierarchy(Classes, RD);
3652   Classes.front().initialize(/*Parent=*/nullptr, /*Specifier=*/nullptr);
3653   detectAmbiguousBases(Classes);
3654   int Flags = 0;
3655   for (auto Class : Classes) {
3656     if (Class.RD->getNumBases() > 1)
3657       Flags |= HasBranchingHierarchy;
3658     // Note: cl.exe does not calculate "HasAmbiguousBases" correctly.  We
3659     // believe the field isn't actually used.
3660     if (Class.Flags & MSRTTIClass::IsAmbiguous)
3661       Flags |= HasAmbiguousBases;
3662   }
3663   if ((Flags & HasBranchingHierarchy) && RD->getNumVBases() != 0)
3664     Flags |= HasVirtualBranchingHierarchy;
3665   // These gep indices are used to get the address of the first element of the
3666   // base class array.
3667   llvm::Value *GEPIndices[] = {llvm::ConstantInt::get(CGM.IntTy, 0),
3668                                llvm::ConstantInt::get(CGM.IntTy, 0)};
3669 
3670   // Forward-declare the class hierarchy descriptor
3671   auto Type = ABI.getClassHierarchyDescriptorType();
3672   auto CHD = new llvm::GlobalVariable(Module, Type, /*isConstant=*/true, Linkage,
3673                                       /*Initializer=*/nullptr,
3674                                       MangledName);
3675   if (CHD->isWeakForLinker())
3676     CHD->setComdat(CGM.getModule().getOrInsertComdat(CHD->getName()));
3677 
3678   auto *Bases = getBaseClassArray(Classes);
3679 
3680   // Initialize the base class ClassHierarchyDescriptor.
3681   llvm::Constant *Fields[] = {
3682       llvm::ConstantInt::get(CGM.IntTy, 0), // reserved by the runtime
3683       llvm::ConstantInt::get(CGM.IntTy, Flags),
3684       llvm::ConstantInt::get(CGM.IntTy, Classes.size()),
3685       ABI.getImageRelativeConstant(llvm::ConstantExpr::getInBoundsGetElementPtr(
3686           Bases->getValueType(), Bases,
3687           llvm::ArrayRef<llvm::Value *>(GEPIndices))),
3688   };
3689   CHD->setInitializer(llvm::ConstantStruct::get(Type, Fields));
3690   return CHD;
3691 }
3692 
3693 llvm::GlobalVariable *
getBaseClassArray(SmallVectorImpl<MSRTTIClass> & Classes)3694 MSRTTIBuilder::getBaseClassArray(SmallVectorImpl<MSRTTIClass> &Classes) {
3695   SmallString<256> MangledName;
3696   {
3697     llvm::raw_svector_ostream Out(MangledName);
3698     ABI.getMangleContext().mangleCXXRTTIBaseClassArray(RD, Out);
3699   }
3700 
3701   // Forward-declare the base class array.
3702   // cl.exe pads the base class array with 1 (in 32 bit mode) or 4 (in 64 bit
3703   // mode) bytes of padding.  We provide a pointer sized amount of padding by
3704   // adding +1 to Classes.size().  The sections have pointer alignment and are
3705   // marked pick-any so it shouldn't matter.
3706   llvm::Type *PtrType = ABI.getImageRelativeType(
3707       ABI.getBaseClassDescriptorType()->getPointerTo());
3708   auto *ArrType = llvm::ArrayType::get(PtrType, Classes.size() + 1);
3709   auto *BCA =
3710       new llvm::GlobalVariable(Module, ArrType,
3711                                /*isConstant=*/true, Linkage,
3712                                /*Initializer=*/nullptr, MangledName);
3713   if (BCA->isWeakForLinker())
3714     BCA->setComdat(CGM.getModule().getOrInsertComdat(BCA->getName()));
3715 
3716   // Initialize the BaseClassArray.
3717   SmallVector<llvm::Constant *, 8> BaseClassArrayData;
3718   for (MSRTTIClass &Class : Classes)
3719     BaseClassArrayData.push_back(
3720         ABI.getImageRelativeConstant(getBaseClassDescriptor(Class)));
3721   BaseClassArrayData.push_back(llvm::Constant::getNullValue(PtrType));
3722   BCA->setInitializer(llvm::ConstantArray::get(ArrType, BaseClassArrayData));
3723   return BCA;
3724 }
3725 
3726 llvm::GlobalVariable *
getBaseClassDescriptor(const MSRTTIClass & Class)3727 MSRTTIBuilder::getBaseClassDescriptor(const MSRTTIClass &Class) {
3728   // Compute the fields for the BaseClassDescriptor.  They are computed up front
3729   // because they are mangled into the name of the object.
3730   uint32_t OffsetInVBTable = 0;
3731   int32_t VBPtrOffset = -1;
3732   if (Class.VirtualRoot) {
3733     auto &VTableContext = CGM.getMicrosoftVTableContext();
3734     OffsetInVBTable = VTableContext.getVBTableIndex(RD, Class.VirtualRoot) * 4;
3735     VBPtrOffset = Context.getASTRecordLayout(RD).getVBPtrOffset().getQuantity();
3736   }
3737 
3738   SmallString<256> MangledName;
3739   {
3740     llvm::raw_svector_ostream Out(MangledName);
3741     ABI.getMangleContext().mangleCXXRTTIBaseClassDescriptor(
3742         Class.RD, Class.OffsetInVBase, VBPtrOffset, OffsetInVBTable,
3743         Class.Flags, Out);
3744   }
3745 
3746   // Check to see if we've already declared this object.
3747   if (auto BCD = Module.getNamedGlobal(MangledName))
3748     return BCD;
3749 
3750   // Forward-declare the base class descriptor.
3751   auto Type = ABI.getBaseClassDescriptorType();
3752   auto BCD =
3753       new llvm::GlobalVariable(Module, Type, /*isConstant=*/true, Linkage,
3754                                /*Initializer=*/nullptr, MangledName);
3755   if (BCD->isWeakForLinker())
3756     BCD->setComdat(CGM.getModule().getOrInsertComdat(BCD->getName()));
3757 
3758   // Initialize the BaseClassDescriptor.
3759   llvm::Constant *Fields[] = {
3760       ABI.getImageRelativeConstant(
3761           ABI.getAddrOfRTTIDescriptor(Context.getTypeDeclType(Class.RD))),
3762       llvm::ConstantInt::get(CGM.IntTy, Class.NumBases),
3763       llvm::ConstantInt::get(CGM.IntTy, Class.OffsetInVBase),
3764       llvm::ConstantInt::get(CGM.IntTy, VBPtrOffset),
3765       llvm::ConstantInt::get(CGM.IntTy, OffsetInVBTable),
3766       llvm::ConstantInt::get(CGM.IntTy, Class.Flags),
3767       ABI.getImageRelativeConstant(
3768           MSRTTIBuilder(ABI, Class.RD).getClassHierarchyDescriptor()),
3769   };
3770   BCD->setInitializer(llvm::ConstantStruct::get(Type, Fields));
3771   return BCD;
3772 }
3773 
3774 llvm::GlobalVariable *
getCompleteObjectLocator(const VPtrInfo & Info)3775 MSRTTIBuilder::getCompleteObjectLocator(const VPtrInfo &Info) {
3776   SmallString<256> MangledName;
3777   {
3778     llvm::raw_svector_ostream Out(MangledName);
3779     ABI.getMangleContext().mangleCXXRTTICompleteObjectLocator(RD, Info.MangledPath, Out);
3780   }
3781 
3782   // Check to see if we've already computed this complete object locator.
3783   if (auto COL = Module.getNamedGlobal(MangledName))
3784     return COL;
3785 
3786   // Compute the fields of the complete object locator.
3787   int OffsetToTop = Info.FullOffsetInMDC.getQuantity();
3788   int VFPtrOffset = 0;
3789   // The offset includes the vtordisp if one exists.
3790   if (const CXXRecordDecl *VBase = Info.getVBaseWithVPtr())
3791     if (Context.getASTRecordLayout(RD)
3792       .getVBaseOffsetsMap()
3793       .find(VBase)
3794       ->second.hasVtorDisp())
3795       VFPtrOffset = Info.NonVirtualOffset.getQuantity() + 4;
3796 
3797   // Forward-declare the complete object locator.
3798   llvm::StructType *Type = ABI.getCompleteObjectLocatorType();
3799   auto COL = new llvm::GlobalVariable(Module, Type, /*isConstant=*/true, Linkage,
3800     /*Initializer=*/nullptr, MangledName);
3801 
3802   // Initialize the CompleteObjectLocator.
3803   llvm::Constant *Fields[] = {
3804       llvm::ConstantInt::get(CGM.IntTy, ABI.isImageRelative()),
3805       llvm::ConstantInt::get(CGM.IntTy, OffsetToTop),
3806       llvm::ConstantInt::get(CGM.IntTy, VFPtrOffset),
3807       ABI.getImageRelativeConstant(
3808           CGM.GetAddrOfRTTIDescriptor(Context.getTypeDeclType(RD))),
3809       ABI.getImageRelativeConstant(getClassHierarchyDescriptor()),
3810       ABI.getImageRelativeConstant(COL),
3811   };
3812   llvm::ArrayRef<llvm::Constant *> FieldsRef(Fields);
3813   if (!ABI.isImageRelative())
3814     FieldsRef = FieldsRef.drop_back();
3815   COL->setInitializer(llvm::ConstantStruct::get(Type, FieldsRef));
3816   if (COL->isWeakForLinker())
3817     COL->setComdat(CGM.getModule().getOrInsertComdat(COL->getName()));
3818   return COL;
3819 }
3820 
decomposeTypeForEH(ASTContext & Context,QualType T,bool & IsConst,bool & IsVolatile,bool & IsUnaligned)3821 static QualType decomposeTypeForEH(ASTContext &Context, QualType T,
3822                                    bool &IsConst, bool &IsVolatile,
3823                                    bool &IsUnaligned) {
3824   T = Context.getExceptionObjectType(T);
3825 
3826   // C++14 [except.handle]p3:
3827   //   A handler is a match for an exception object of type E if [...]
3828   //     - the handler is of type cv T or const T& where T is a pointer type and
3829   //       E is a pointer type that can be converted to T by [...]
3830   //         - a qualification conversion
3831   IsConst = false;
3832   IsVolatile = false;
3833   IsUnaligned = false;
3834   QualType PointeeType = T->getPointeeType();
3835   if (!PointeeType.isNull()) {
3836     IsConst = PointeeType.isConstQualified();
3837     IsVolatile = PointeeType.isVolatileQualified();
3838     IsUnaligned = PointeeType.getQualifiers().hasUnaligned();
3839   }
3840 
3841   // Member pointer types like "const int A::*" are represented by having RTTI
3842   // for "int A::*" and separately storing the const qualifier.
3843   if (const auto *MPTy = T->getAs<MemberPointerType>())
3844     T = Context.getMemberPointerType(PointeeType.getUnqualifiedType(),
3845                                      MPTy->getClass());
3846 
3847   // Pointer types like "const int * const *" are represented by having RTTI
3848   // for "const int **" and separately storing the const qualifier.
3849   if (T->isPointerType())
3850     T = Context.getPointerType(PointeeType.getUnqualifiedType());
3851 
3852   return T;
3853 }
3854 
3855 CatchTypeInfo
getAddrOfCXXCatchHandlerType(QualType Type,QualType CatchHandlerType)3856 MicrosoftCXXABI::getAddrOfCXXCatchHandlerType(QualType Type,
3857                                               QualType CatchHandlerType) {
3858   // TypeDescriptors for exceptions never have qualified pointer types,
3859   // qualifiers are stored separately in order to support qualification
3860   // conversions.
3861   bool IsConst, IsVolatile, IsUnaligned;
3862   Type =
3863       decomposeTypeForEH(getContext(), Type, IsConst, IsVolatile, IsUnaligned);
3864 
3865   bool IsReference = CatchHandlerType->isReferenceType();
3866 
3867   uint32_t Flags = 0;
3868   if (IsConst)
3869     Flags |= 1;
3870   if (IsVolatile)
3871     Flags |= 2;
3872   if (IsUnaligned)
3873     Flags |= 4;
3874   if (IsReference)
3875     Flags |= 8;
3876 
3877   return CatchTypeInfo{getAddrOfRTTIDescriptor(Type)->stripPointerCasts(),
3878                        Flags};
3879 }
3880 
3881 /// Gets a TypeDescriptor.  Returns a llvm::Constant * rather than a
3882 /// llvm::GlobalVariable * because different type descriptors have different
3883 /// types, and need to be abstracted.  They are abstracting by casting the
3884 /// address to an Int8PtrTy.
getAddrOfRTTIDescriptor(QualType Type)3885 llvm::Constant *MicrosoftCXXABI::getAddrOfRTTIDescriptor(QualType Type) {
3886   SmallString<256> MangledName;
3887   {
3888     llvm::raw_svector_ostream Out(MangledName);
3889     getMangleContext().mangleCXXRTTI(Type, Out);
3890   }
3891 
3892   // Check to see if we've already declared this TypeDescriptor.
3893   if (llvm::GlobalVariable *GV = CGM.getModule().getNamedGlobal(MangledName))
3894     return llvm::ConstantExpr::getBitCast(GV, CGM.Int8PtrTy);
3895 
3896   // Note for the future: If we would ever like to do deferred emission of
3897   // RTTI, check if emitting vtables opportunistically need any adjustment.
3898 
3899   // Compute the fields for the TypeDescriptor.
3900   SmallString<256> TypeInfoString;
3901   {
3902     llvm::raw_svector_ostream Out(TypeInfoString);
3903     getMangleContext().mangleCXXRTTIName(Type, Out);
3904   }
3905 
3906   // Declare and initialize the TypeDescriptor.
3907   llvm::Constant *Fields[] = {
3908     getTypeInfoVTable(CGM),                        // VFPtr
3909     llvm::ConstantPointerNull::get(CGM.Int8PtrTy), // Runtime data
3910     llvm::ConstantDataArray::getString(CGM.getLLVMContext(), TypeInfoString)};
3911   llvm::StructType *TypeDescriptorType =
3912       getTypeDescriptorType(TypeInfoString);
3913   auto *Var = new llvm::GlobalVariable(
3914       CGM.getModule(), TypeDescriptorType, /*isConstant=*/false,
3915       getLinkageForRTTI(Type),
3916       llvm::ConstantStruct::get(TypeDescriptorType, Fields),
3917       MangledName);
3918   if (Var->isWeakForLinker())
3919     Var->setComdat(CGM.getModule().getOrInsertComdat(Var->getName()));
3920   return llvm::ConstantExpr::getBitCast(Var, CGM.Int8PtrTy);
3921 }
3922 
3923 /// Gets or a creates a Microsoft CompleteObjectLocator.
3924 llvm::GlobalVariable *
getMSCompleteObjectLocator(const CXXRecordDecl * RD,const VPtrInfo & Info)3925 MicrosoftCXXABI::getMSCompleteObjectLocator(const CXXRecordDecl *RD,
3926                                             const VPtrInfo &Info) {
3927   return MSRTTIBuilder(*this, RD).getCompleteObjectLocator(Info);
3928 }
3929 
emitCXXStructor(GlobalDecl GD)3930 void MicrosoftCXXABI::emitCXXStructor(GlobalDecl GD) {
3931   if (auto *ctor = dyn_cast<CXXConstructorDecl>(GD.getDecl())) {
3932     // There are no constructor variants, always emit the complete destructor.
3933     llvm::Function *Fn =
3934         CGM.codegenCXXStructor(GD.getWithCtorType(Ctor_Complete));
3935     CGM.maybeSetTrivialComdat(*ctor, *Fn);
3936     return;
3937   }
3938 
3939   auto *dtor = cast<CXXDestructorDecl>(GD.getDecl());
3940 
3941   // Emit the base destructor if the base and complete (vbase) destructors are
3942   // equivalent. This effectively implements -mconstructor-aliases as part of
3943   // the ABI.
3944   if (GD.getDtorType() == Dtor_Complete &&
3945       dtor->getParent()->getNumVBases() == 0)
3946     GD = GD.getWithDtorType(Dtor_Base);
3947 
3948   // The base destructor is equivalent to the base destructor of its
3949   // base class if there is exactly one non-virtual base class with a
3950   // non-trivial destructor, there are no fields with a non-trivial
3951   // destructor, and the body of the destructor is trivial.
3952   if (GD.getDtorType() == Dtor_Base && !CGM.TryEmitBaseDestructorAsAlias(dtor))
3953     return;
3954 
3955   llvm::Function *Fn = CGM.codegenCXXStructor(GD);
3956   if (Fn->isWeakForLinker())
3957     Fn->setComdat(CGM.getModule().getOrInsertComdat(Fn->getName()));
3958 }
3959 
3960 llvm::Function *
getAddrOfCXXCtorClosure(const CXXConstructorDecl * CD,CXXCtorType CT)3961 MicrosoftCXXABI::getAddrOfCXXCtorClosure(const CXXConstructorDecl *CD,
3962                                          CXXCtorType CT) {
3963   assert(CT == Ctor_CopyingClosure || CT == Ctor_DefaultClosure);
3964 
3965   // Calculate the mangled name.
3966   SmallString<256> ThunkName;
3967   llvm::raw_svector_ostream Out(ThunkName);
3968   getMangleContext().mangleName(GlobalDecl(CD, CT), Out);
3969 
3970   // If the thunk has been generated previously, just return it.
3971   if (llvm::GlobalValue *GV = CGM.getModule().getNamedValue(ThunkName))
3972     return cast<llvm::Function>(GV);
3973 
3974   // Create the llvm::Function.
3975   const CGFunctionInfo &FnInfo = CGM.getTypes().arrangeMSCtorClosure(CD, CT);
3976   llvm::FunctionType *ThunkTy = CGM.getTypes().GetFunctionType(FnInfo);
3977   const CXXRecordDecl *RD = CD->getParent();
3978   QualType RecordTy = getContext().getRecordType(RD);
3979   llvm::Function *ThunkFn = llvm::Function::Create(
3980       ThunkTy, getLinkageForRTTI(RecordTy), ThunkName.str(), &CGM.getModule());
3981   ThunkFn->setCallingConv(static_cast<llvm::CallingConv::ID>(
3982       FnInfo.getEffectiveCallingConvention()));
3983   if (ThunkFn->isWeakForLinker())
3984     ThunkFn->setComdat(CGM.getModule().getOrInsertComdat(ThunkFn->getName()));
3985   bool IsCopy = CT == Ctor_CopyingClosure;
3986 
3987   // Start codegen.
3988   CodeGenFunction CGF(CGM);
3989   CGF.CurGD = GlobalDecl(CD, Ctor_Complete);
3990 
3991   // Build FunctionArgs.
3992   FunctionArgList FunctionArgs;
3993 
3994   // A constructor always starts with a 'this' pointer as its first argument.
3995   buildThisParam(CGF, FunctionArgs);
3996 
3997   // Following the 'this' pointer is a reference to the source object that we
3998   // are copying from.
3999   ImplicitParamDecl SrcParam(
4000       getContext(), /*DC=*/nullptr, SourceLocation(),
4001       &getContext().Idents.get("src"),
4002       getContext().getLValueReferenceType(RecordTy,
4003                                           /*SpelledAsLValue=*/true),
4004       ImplicitParamDecl::Other);
4005   if (IsCopy)
4006     FunctionArgs.push_back(&SrcParam);
4007 
4008   // Constructors for classes which utilize virtual bases have an additional
4009   // parameter which indicates whether or not it is being delegated to by a more
4010   // derived constructor.
4011   ImplicitParamDecl IsMostDerived(getContext(), /*DC=*/nullptr,
4012                                   SourceLocation(),
4013                                   &getContext().Idents.get("is_most_derived"),
4014                                   getContext().IntTy, ImplicitParamDecl::Other);
4015   // Only add the parameter to the list if the class has virtual bases.
4016   if (RD->getNumVBases() > 0)
4017     FunctionArgs.push_back(&IsMostDerived);
4018 
4019   // Start defining the function.
4020   auto NL = ApplyDebugLocation::CreateEmpty(CGF);
4021   CGF.StartFunction(GlobalDecl(), FnInfo.getReturnType(), ThunkFn, FnInfo,
4022                     FunctionArgs, CD->getLocation(), SourceLocation());
4023   // Create a scope with an artificial location for the body of this function.
4024   auto AL = ApplyDebugLocation::CreateArtificial(CGF);
4025   setCXXABIThisValue(CGF, loadIncomingCXXThis(CGF));
4026   llvm::Value *This = getThisValue(CGF);
4027 
4028   llvm::Value *SrcVal =
4029       IsCopy ? CGF.Builder.CreateLoad(CGF.GetAddrOfLocalVar(&SrcParam), "src")
4030              : nullptr;
4031 
4032   CallArgList Args;
4033 
4034   // Push the this ptr.
4035   Args.add(RValue::get(This), CD->getThisType());
4036 
4037   // Push the src ptr.
4038   if (SrcVal)
4039     Args.add(RValue::get(SrcVal), SrcParam.getType());
4040 
4041   // Add the rest of the default arguments.
4042   SmallVector<const Stmt *, 4> ArgVec;
4043   ArrayRef<ParmVarDecl *> params = CD->parameters().drop_front(IsCopy ? 1 : 0);
4044   for (const ParmVarDecl *PD : params) {
4045     assert(PD->hasDefaultArg() && "ctor closure lacks default args");
4046     ArgVec.push_back(PD->getDefaultArg());
4047   }
4048 
4049   CodeGenFunction::RunCleanupsScope Cleanups(CGF);
4050 
4051   const auto *FPT = CD->getType()->castAs<FunctionProtoType>();
4052   CGF.EmitCallArgs(Args, FPT, llvm::makeArrayRef(ArgVec), CD, IsCopy ? 1 : 0);
4053 
4054   // Insert any ABI-specific implicit constructor arguments.
4055   AddedStructorArgCounts ExtraArgs =
4056       addImplicitConstructorArgs(CGF, CD, Ctor_Complete,
4057                                  /*ForVirtualBase=*/false,
4058                                  /*Delegating=*/false, Args);
4059   // Call the destructor with our arguments.
4060   llvm::Constant *CalleePtr =
4061       CGM.getAddrOfCXXStructor(GlobalDecl(CD, Ctor_Complete));
4062   CGCallee Callee =
4063       CGCallee::forDirect(CalleePtr, GlobalDecl(CD, Ctor_Complete));
4064   const CGFunctionInfo &CalleeInfo = CGM.getTypes().arrangeCXXConstructorCall(
4065       Args, CD, Ctor_Complete, ExtraArgs.Prefix, ExtraArgs.Suffix);
4066   CGF.EmitCall(CalleeInfo, Callee, ReturnValueSlot(), Args);
4067 
4068   Cleanups.ForceCleanup();
4069 
4070   // Emit the ret instruction, remove any temporary instructions created for the
4071   // aid of CodeGen.
4072   CGF.FinishFunction(SourceLocation());
4073 
4074   return ThunkFn;
4075 }
4076 
getCatchableType(QualType T,uint32_t NVOffset,int32_t VBPtrOffset,uint32_t VBIndex)4077 llvm::Constant *MicrosoftCXXABI::getCatchableType(QualType T,
4078                                                   uint32_t NVOffset,
4079                                                   int32_t VBPtrOffset,
4080                                                   uint32_t VBIndex) {
4081   assert(!T->isReferenceType());
4082 
4083   CXXRecordDecl *RD = T->getAsCXXRecordDecl();
4084   const CXXConstructorDecl *CD =
4085       RD ? CGM.getContext().getCopyConstructorForExceptionObject(RD) : nullptr;
4086   CXXCtorType CT = Ctor_Complete;
4087   if (CD)
4088     if (!hasDefaultCXXMethodCC(getContext(), CD) || CD->getNumParams() != 1)
4089       CT = Ctor_CopyingClosure;
4090 
4091   uint32_t Size = getContext().getTypeSizeInChars(T).getQuantity();
4092   SmallString<256> MangledName;
4093   {
4094     llvm::raw_svector_ostream Out(MangledName);
4095     getMangleContext().mangleCXXCatchableType(T, CD, CT, Size, NVOffset,
4096                                               VBPtrOffset, VBIndex, Out);
4097   }
4098   if (llvm::GlobalVariable *GV = CGM.getModule().getNamedGlobal(MangledName))
4099     return getImageRelativeConstant(GV);
4100 
4101   // The TypeDescriptor is used by the runtime to determine if a catch handler
4102   // is appropriate for the exception object.
4103   llvm::Constant *TD = getImageRelativeConstant(getAddrOfRTTIDescriptor(T));
4104 
4105   // The runtime is responsible for calling the copy constructor if the
4106   // exception is caught by value.
4107   llvm::Constant *CopyCtor;
4108   if (CD) {
4109     if (CT == Ctor_CopyingClosure)
4110       CopyCtor = getAddrOfCXXCtorClosure(CD, Ctor_CopyingClosure);
4111     else
4112       CopyCtor = CGM.getAddrOfCXXStructor(GlobalDecl(CD, Ctor_Complete));
4113 
4114     CopyCtor = llvm::ConstantExpr::getBitCast(CopyCtor, CGM.Int8PtrTy);
4115   } else {
4116     CopyCtor = llvm::Constant::getNullValue(CGM.Int8PtrTy);
4117   }
4118   CopyCtor = getImageRelativeConstant(CopyCtor);
4119 
4120   bool IsScalar = !RD;
4121   bool HasVirtualBases = false;
4122   bool IsStdBadAlloc = false; // std::bad_alloc is special for some reason.
4123   QualType PointeeType = T;
4124   if (T->isPointerType())
4125     PointeeType = T->getPointeeType();
4126   if (const CXXRecordDecl *RD = PointeeType->getAsCXXRecordDecl()) {
4127     HasVirtualBases = RD->getNumVBases() > 0;
4128     if (IdentifierInfo *II = RD->getIdentifier())
4129       IsStdBadAlloc = II->isStr("bad_alloc") && RD->isInStdNamespace();
4130   }
4131 
4132   // Encode the relevant CatchableType properties into the Flags bitfield.
4133   // FIXME: Figure out how bits 2 or 8 can get set.
4134   uint32_t Flags = 0;
4135   if (IsScalar)
4136     Flags |= 1;
4137   if (HasVirtualBases)
4138     Flags |= 4;
4139   if (IsStdBadAlloc)
4140     Flags |= 16;
4141 
4142   llvm::Constant *Fields[] = {
4143       llvm::ConstantInt::get(CGM.IntTy, Flags),       // Flags
4144       TD,                                             // TypeDescriptor
4145       llvm::ConstantInt::get(CGM.IntTy, NVOffset),    // NonVirtualAdjustment
4146       llvm::ConstantInt::get(CGM.IntTy, VBPtrOffset), // OffsetToVBPtr
4147       llvm::ConstantInt::get(CGM.IntTy, VBIndex),     // VBTableIndex
4148       llvm::ConstantInt::get(CGM.IntTy, Size),        // Size
4149       CopyCtor                                        // CopyCtor
4150   };
4151   llvm::StructType *CTType = getCatchableTypeType();
4152   auto *GV = new llvm::GlobalVariable(
4153       CGM.getModule(), CTType, /*isConstant=*/true, getLinkageForRTTI(T),
4154       llvm::ConstantStruct::get(CTType, Fields), MangledName);
4155   GV->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
4156   GV->setSection(".xdata");
4157   if (GV->isWeakForLinker())
4158     GV->setComdat(CGM.getModule().getOrInsertComdat(GV->getName()));
4159   return getImageRelativeConstant(GV);
4160 }
4161 
getCatchableTypeArray(QualType T)4162 llvm::GlobalVariable *MicrosoftCXXABI::getCatchableTypeArray(QualType T) {
4163   assert(!T->isReferenceType());
4164 
4165   // See if we've already generated a CatchableTypeArray for this type before.
4166   llvm::GlobalVariable *&CTA = CatchableTypeArrays[T];
4167   if (CTA)
4168     return CTA;
4169 
4170   // Ensure that we don't have duplicate entries in our CatchableTypeArray by
4171   // using a SmallSetVector.  Duplicates may arise due to virtual bases
4172   // occurring more than once in the hierarchy.
4173   llvm::SmallSetVector<llvm::Constant *, 2> CatchableTypes;
4174 
4175   // C++14 [except.handle]p3:
4176   //   A handler is a match for an exception object of type E if [...]
4177   //     - the handler is of type cv T or cv T& and T is an unambiguous public
4178   //       base class of E, or
4179   //     - the handler is of type cv T or const T& where T is a pointer type and
4180   //       E is a pointer type that can be converted to T by [...]
4181   //         - a standard pointer conversion (4.10) not involving conversions to
4182   //           pointers to private or protected or ambiguous classes
4183   const CXXRecordDecl *MostDerivedClass = nullptr;
4184   bool IsPointer = T->isPointerType();
4185   if (IsPointer)
4186     MostDerivedClass = T->getPointeeType()->getAsCXXRecordDecl();
4187   else
4188     MostDerivedClass = T->getAsCXXRecordDecl();
4189 
4190   // Collect all the unambiguous public bases of the MostDerivedClass.
4191   if (MostDerivedClass) {
4192     const ASTContext &Context = getContext();
4193     const ASTRecordLayout &MostDerivedLayout =
4194         Context.getASTRecordLayout(MostDerivedClass);
4195     MicrosoftVTableContext &VTableContext = CGM.getMicrosoftVTableContext();
4196     SmallVector<MSRTTIClass, 8> Classes;
4197     serializeClassHierarchy(Classes, MostDerivedClass);
4198     Classes.front().initialize(/*Parent=*/nullptr, /*Specifier=*/nullptr);
4199     detectAmbiguousBases(Classes);
4200     for (const MSRTTIClass &Class : Classes) {
4201       // Skip any ambiguous or private bases.
4202       if (Class.Flags &
4203           (MSRTTIClass::IsPrivateOnPath | MSRTTIClass::IsAmbiguous))
4204         continue;
4205       // Write down how to convert from a derived pointer to a base pointer.
4206       uint32_t OffsetInVBTable = 0;
4207       int32_t VBPtrOffset = -1;
4208       if (Class.VirtualRoot) {
4209         OffsetInVBTable =
4210           VTableContext.getVBTableIndex(MostDerivedClass, Class.VirtualRoot)*4;
4211         VBPtrOffset = MostDerivedLayout.getVBPtrOffset().getQuantity();
4212       }
4213 
4214       // Turn our record back into a pointer if the exception object is a
4215       // pointer.
4216       QualType RTTITy = QualType(Class.RD->getTypeForDecl(), 0);
4217       if (IsPointer)
4218         RTTITy = Context.getPointerType(RTTITy);
4219       CatchableTypes.insert(getCatchableType(RTTITy, Class.OffsetInVBase,
4220                                              VBPtrOffset, OffsetInVBTable));
4221     }
4222   }
4223 
4224   // C++14 [except.handle]p3:
4225   //   A handler is a match for an exception object of type E if
4226   //     - The handler is of type cv T or cv T& and E and T are the same type
4227   //       (ignoring the top-level cv-qualifiers)
4228   CatchableTypes.insert(getCatchableType(T));
4229 
4230   // C++14 [except.handle]p3:
4231   //   A handler is a match for an exception object of type E if
4232   //     - the handler is of type cv T or const T& where T is a pointer type and
4233   //       E is a pointer type that can be converted to T by [...]
4234   //         - a standard pointer conversion (4.10) not involving conversions to
4235   //           pointers to private or protected or ambiguous classes
4236   //
4237   // C++14 [conv.ptr]p2:
4238   //   A prvalue of type "pointer to cv T," where T is an object type, can be
4239   //   converted to a prvalue of type "pointer to cv void".
4240   if (IsPointer && T->getPointeeType()->isObjectType())
4241     CatchableTypes.insert(getCatchableType(getContext().VoidPtrTy));
4242 
4243   // C++14 [except.handle]p3:
4244   //   A handler is a match for an exception object of type E if [...]
4245   //     - the handler is of type cv T or const T& where T is a pointer or
4246   //       pointer to member type and E is std::nullptr_t.
4247   //
4248   // We cannot possibly list all possible pointer types here, making this
4249   // implementation incompatible with the standard.  However, MSVC includes an
4250   // entry for pointer-to-void in this case.  Let's do the same.
4251   if (T->isNullPtrType())
4252     CatchableTypes.insert(getCatchableType(getContext().VoidPtrTy));
4253 
4254   uint32_t NumEntries = CatchableTypes.size();
4255   llvm::Type *CTType =
4256       getImageRelativeType(getCatchableTypeType()->getPointerTo());
4257   llvm::ArrayType *AT = llvm::ArrayType::get(CTType, NumEntries);
4258   llvm::StructType *CTAType = getCatchableTypeArrayType(NumEntries);
4259   llvm::Constant *Fields[] = {
4260       llvm::ConstantInt::get(CGM.IntTy, NumEntries),    // NumEntries
4261       llvm::ConstantArray::get(
4262           AT, llvm::makeArrayRef(CatchableTypes.begin(),
4263                                  CatchableTypes.end())) // CatchableTypes
4264   };
4265   SmallString<256> MangledName;
4266   {
4267     llvm::raw_svector_ostream Out(MangledName);
4268     getMangleContext().mangleCXXCatchableTypeArray(T, NumEntries, Out);
4269   }
4270   CTA = new llvm::GlobalVariable(
4271       CGM.getModule(), CTAType, /*isConstant=*/true, getLinkageForRTTI(T),
4272       llvm::ConstantStruct::get(CTAType, Fields), MangledName);
4273   CTA->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
4274   CTA->setSection(".xdata");
4275   if (CTA->isWeakForLinker())
4276     CTA->setComdat(CGM.getModule().getOrInsertComdat(CTA->getName()));
4277   return CTA;
4278 }
4279 
getThrowInfo(QualType T)4280 llvm::GlobalVariable *MicrosoftCXXABI::getThrowInfo(QualType T) {
4281   bool IsConst, IsVolatile, IsUnaligned;
4282   T = decomposeTypeForEH(getContext(), T, IsConst, IsVolatile, IsUnaligned);
4283 
4284   // The CatchableTypeArray enumerates the various (CV-unqualified) types that
4285   // the exception object may be caught as.
4286   llvm::GlobalVariable *CTA = getCatchableTypeArray(T);
4287   // The first field in a CatchableTypeArray is the number of CatchableTypes.
4288   // This is used as a component of the mangled name which means that we need to
4289   // know what it is in order to see if we have previously generated the
4290   // ThrowInfo.
4291   uint32_t NumEntries =
4292       cast<llvm::ConstantInt>(CTA->getInitializer()->getAggregateElement(0U))
4293           ->getLimitedValue();
4294 
4295   SmallString<256> MangledName;
4296   {
4297     llvm::raw_svector_ostream Out(MangledName);
4298     getMangleContext().mangleCXXThrowInfo(T, IsConst, IsVolatile, IsUnaligned,
4299                                           NumEntries, Out);
4300   }
4301 
4302   // Reuse a previously generated ThrowInfo if we have generated an appropriate
4303   // one before.
4304   if (llvm::GlobalVariable *GV = CGM.getModule().getNamedGlobal(MangledName))
4305     return GV;
4306 
4307   // The RTTI TypeDescriptor uses an unqualified type but catch clauses must
4308   // be at least as CV qualified.  Encode this requirement into the Flags
4309   // bitfield.
4310   uint32_t Flags = 0;
4311   if (IsConst)
4312     Flags |= 1;
4313   if (IsVolatile)
4314     Flags |= 2;
4315   if (IsUnaligned)
4316     Flags |= 4;
4317 
4318   // The cleanup-function (a destructor) must be called when the exception
4319   // object's lifetime ends.
4320   llvm::Constant *CleanupFn = llvm::Constant::getNullValue(CGM.Int8PtrTy);
4321   if (const CXXRecordDecl *RD = T->getAsCXXRecordDecl())
4322     if (CXXDestructorDecl *DtorD = RD->getDestructor())
4323       if (!DtorD->isTrivial())
4324         CleanupFn = llvm::ConstantExpr::getBitCast(
4325             CGM.getAddrOfCXXStructor(GlobalDecl(DtorD, Dtor_Complete)),
4326             CGM.Int8PtrTy);
4327   // This is unused as far as we can tell, initialize it to null.
4328   llvm::Constant *ForwardCompat =
4329       getImageRelativeConstant(llvm::Constant::getNullValue(CGM.Int8PtrTy));
4330   llvm::Constant *PointerToCatchableTypes = getImageRelativeConstant(
4331       llvm::ConstantExpr::getBitCast(CTA, CGM.Int8PtrTy));
4332   llvm::StructType *TIType = getThrowInfoType();
4333   llvm::Constant *Fields[] = {
4334       llvm::ConstantInt::get(CGM.IntTy, Flags), // Flags
4335       getImageRelativeConstant(CleanupFn),      // CleanupFn
4336       ForwardCompat,                            // ForwardCompat
4337       PointerToCatchableTypes                   // CatchableTypeArray
4338   };
4339   auto *GV = new llvm::GlobalVariable(
4340       CGM.getModule(), TIType, /*isConstant=*/true, getLinkageForRTTI(T),
4341       llvm::ConstantStruct::get(TIType, Fields), MangledName.str());
4342   GV->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
4343   GV->setSection(".xdata");
4344   if (GV->isWeakForLinker())
4345     GV->setComdat(CGM.getModule().getOrInsertComdat(GV->getName()));
4346   return GV;
4347 }
4348 
emitThrow(CodeGenFunction & CGF,const CXXThrowExpr * E)4349 void MicrosoftCXXABI::emitThrow(CodeGenFunction &CGF, const CXXThrowExpr *E) {
4350   const Expr *SubExpr = E->getSubExpr();
4351   QualType ThrowType = SubExpr->getType();
4352   // The exception object lives on the stack and it's address is passed to the
4353   // runtime function.
4354   Address AI = CGF.CreateMemTemp(ThrowType);
4355   CGF.EmitAnyExprToMem(SubExpr, AI, ThrowType.getQualifiers(),
4356                        /*IsInit=*/true);
4357 
4358   // The so-called ThrowInfo is used to describe how the exception object may be
4359   // caught.
4360   llvm::GlobalVariable *TI = getThrowInfo(ThrowType);
4361 
4362   // Call into the runtime to throw the exception.
4363   llvm::Value *Args[] = {
4364     CGF.Builder.CreateBitCast(AI.getPointer(), CGM.Int8PtrTy),
4365     TI
4366   };
4367   CGF.EmitNoreturnRuntimeCallOrInvoke(getThrowFn(), Args);
4368 }
4369 
4370 std::pair<llvm::Value *, const CXXRecordDecl *>
LoadVTablePtr(CodeGenFunction & CGF,Address This,const CXXRecordDecl * RD)4371 MicrosoftCXXABI::LoadVTablePtr(CodeGenFunction &CGF, Address This,
4372                                const CXXRecordDecl *RD) {
4373   std::tie(This, std::ignore, RD) =
4374       performBaseAdjustment(CGF, This, QualType(RD->getTypeForDecl(), 0));
4375   return {CGF.GetVTablePtr(This, CGM.Int8PtrTy, RD), RD};
4376 }
4377 
isPermittedToBeHomogeneousAggregate(const CXXRecordDecl * CXXRD) const4378 bool MicrosoftCXXABI::isPermittedToBeHomogeneousAggregate(
4379     const CXXRecordDecl *CXXRD) const {
4380   // MSVC Windows on Arm64 considers a type not HFA if it is not an
4381   // aggregate according to the C++14 spec. This is not consistent with the
4382   // AAPCS64, but is defacto spec on that platform.
4383   return !CGM.getTarget().getTriple().isAArch64() ||
4384          isTrivialForAArch64MSVC(CXXRD);
4385 }
4386