brintos / llvm-project-archived public Read only

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-exception6//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 Microsoft11// Visual C++ ABI, which is actually not very well documented at all outside12// of Microsoft.13//14//===----------------------------------------------------------------------===//15 16#include "ABIInfo.h"17#include "CGCXXABI.h"18#include "CGCleanup.h"19#include "CGDebugInfo.h"20#include "CGVTables.h"21#include "CodeGenModule.h"22#include "CodeGenTypes.h"23#include "TargetInfo.h"24#include "clang/AST/Attr.h"25#include "clang/AST/CXXInheritance.h"26#include "clang/AST/Decl.h"27#include "clang/AST/DeclCXX.h"28#include "clang/AST/StmtCXX.h"29#include "clang/AST/VTableBuilder.h"30#include "clang/CodeGen/ConstantInitBuilder.h"31#include "llvm/ADT/StringExtras.h"32#include "llvm/ADT/StringSet.h"33#include "llvm/IR/Intrinsics.h"34 35using namespace clang;36using namespace CodeGen;37 38namespace {39 40/// Holds all the vbtable globals for a given class.41struct VBTableGlobals {42  const VPtrInfoVector *VBTables;43  SmallVector<llvm::GlobalVariable *, 2> Globals;44};45 46class MicrosoftCXXABI : public CGCXXABI {47public:48  MicrosoftCXXABI(CodeGenModule &CGM)49      : CGCXXABI(CGM), BaseClassDescriptorType(nullptr),50        ClassHierarchyDescriptorType(nullptr),51        CompleteObjectLocatorType(nullptr), CatchableTypeType(nullptr),52        ThrowInfoType(nullptr) {53    assert(!(CGM.getLangOpts().isExplicitDefaultVisibilityExportMapping() ||54             CGM.getLangOpts().isAllDefaultVisibilityExportMapping()) &&55           "visibility export mapping option unimplemented in this ABI");56  }57 58  bool HasThisReturn(GlobalDecl GD) const override;59  bool hasMostDerivedReturn(GlobalDecl GD) const override;60 61  bool classifyReturnType(CGFunctionInfo &FI) const override;62 63  RecordArgABI getRecordArgABI(const CXXRecordDecl *RD) const override;64 65  bool isSRetParameterAfterThis() const override { return true; }66 67  bool isThisCompleteObject(GlobalDecl GD) const override {68    // The Microsoft ABI doesn't use separate complete-object vs.69    // base-object variants of constructors, but it does of destructors.70    if (isa<CXXDestructorDecl>(GD.getDecl())) {71      switch (GD.getDtorType()) {72      case Dtor_Complete:73      case Dtor_Deleting:74        return true;75 76      case Dtor_Base:77        return false;78 79      case Dtor_Comdat: llvm_unreachable("emitting dtor comdat as function?");80      case Dtor_Unified:81        llvm_unreachable("unexpected unified dtor type");82      }83      llvm_unreachable("bad dtor kind");84    }85 86    // No other kinds.87    return false;88  }89 90  size_t getSrcArgforCopyCtor(const CXXConstructorDecl *CD,91                              FunctionArgList &Args) const override {92    assert(Args.size() >= 2 &&93           "expected the arglist to have at least two args!");94    // The 'most_derived' parameter goes second if the ctor is variadic and95    // has v-bases.96    if (CD->getParent()->getNumVBases() > 0 &&97        CD->getType()->castAs<FunctionProtoType>()->isVariadic())98      return 2;99    return 1;100  }101 102  std::vector<CharUnits> getVBPtrOffsets(const CXXRecordDecl *RD) override {103    std::vector<CharUnits> VBPtrOffsets;104    const ASTContext &Context = getContext();105    const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);106 107    const VBTableGlobals &VBGlobals = enumerateVBTables(RD);108    for (const std::unique_ptr<VPtrInfo> &VBT : *VBGlobals.VBTables) {109      const ASTRecordLayout &SubobjectLayout =110          Context.getASTRecordLayout(VBT->IntroducingObject);111      CharUnits Offs = VBT->NonVirtualOffset;112      Offs += SubobjectLayout.getVBPtrOffset();113      if (VBT->getVBaseWithVPtr())114        Offs += Layout.getVBaseClassOffset(VBT->getVBaseWithVPtr());115      VBPtrOffsets.push_back(Offs);116    }117    llvm::array_pod_sort(VBPtrOffsets.begin(), VBPtrOffsets.end());118    return VBPtrOffsets;119  }120 121  StringRef GetPureVirtualCallName() override { return "_purecall"; }122  StringRef GetDeletedVirtualCallName() override { return "_purecall"; }123 124  void emitVirtualObjectDelete(CodeGenFunction &CGF, const CXXDeleteExpr *DE,125                               Address Ptr, QualType ElementType,126                               const CXXDestructorDecl *Dtor) override;127 128  void emitRethrow(CodeGenFunction &CGF, bool isNoReturn) override;129  void emitThrow(CodeGenFunction &CGF, const CXXThrowExpr *E) override;130 131  void emitBeginCatch(CodeGenFunction &CGF, const CXXCatchStmt *C) override;132 133  llvm::GlobalVariable *getMSCompleteObjectLocator(const CXXRecordDecl *RD,134                                                   const VPtrInfo &Info);135 136  llvm::Constant *getAddrOfRTTIDescriptor(QualType Ty) override;137  CatchTypeInfo138  getAddrOfCXXCatchHandlerType(QualType Ty, QualType CatchHandlerType) override;139 140  /// MSVC needs an extra flag to indicate a catchall.141  CatchTypeInfo getCatchAllTypeInfo() override {142    // For -EHa catch(...) must handle HW exception143    // Adjective = HT_IsStdDotDot (0x40), only catch C++ exceptions144    if (getContext().getLangOpts().EHAsynch)145      return CatchTypeInfo{nullptr, 0};146    else147      return CatchTypeInfo{nullptr, 0x40};148  }149 150  bool shouldTypeidBeNullChecked(QualType SrcRecordTy) override;151  void EmitBadTypeidCall(CodeGenFunction &CGF) override;152  llvm::Value *EmitTypeid(CodeGenFunction &CGF, QualType SrcRecordTy,153                          Address ThisPtr,154                          llvm::Type *StdTypeInfoPtrTy) override;155 156  bool shouldDynamicCastCallBeNullChecked(bool SrcIsPtr,157                                          QualType SrcRecordTy) override;158 159  bool shouldEmitExactDynamicCast(QualType DestRecordTy) override {160    // TODO: Add support for exact dynamic_casts.161    return false;162  }163  std::optional<ExactDynamicCastInfo>164  getExactDynamicCastInfo(QualType SrcRecordTy, QualType DestTy,165                          QualType DestRecordTy) override {166    llvm_unreachable("unsupported");167  }168  llvm::Value *emitExactDynamicCast(CodeGenFunction &CGF, Address Value,169                                    QualType SrcRecordTy, QualType DestTy,170                                    QualType DestRecordTy,171                                    const ExactDynamicCastInfo &CastInfo,172                                    llvm::BasicBlock *CastSuccess,173                                    llvm::BasicBlock *CastFail) override {174    llvm_unreachable("unsupported");175  }176 177  llvm::Value *emitDynamicCastCall(CodeGenFunction &CGF, Address Value,178                                   QualType SrcRecordTy, QualType DestTy,179                                   QualType DestRecordTy,180                                   llvm::BasicBlock *CastEnd) override;181 182  llvm::Value *emitDynamicCastToVoid(CodeGenFunction &CGF, Address Value,183                                     QualType SrcRecordTy) override;184 185  bool EmitBadCastCall(CodeGenFunction &CGF) override;186  bool canSpeculativelyEmitVTable(const CXXRecordDecl *RD) const override {187    return false;188  }189 190  llvm::Value *191  GetVirtualBaseClassOffset(CodeGenFunction &CGF, Address This,192                            const CXXRecordDecl *ClassDecl,193                            const CXXRecordDecl *BaseClassDecl) override;194 195  llvm::BasicBlock *196  EmitCtorCompleteObjectHandler(CodeGenFunction &CGF,197                                const CXXRecordDecl *RD) override;198 199  llvm::BasicBlock *200  EmitDtorCompleteObjectHandler(CodeGenFunction &CGF);201 202  void initializeHiddenVirtualInheritanceMembers(CodeGenFunction &CGF,203                                              const CXXRecordDecl *RD) override;204 205  void EmitCXXConstructors(const CXXConstructorDecl *D) override;206 207  // Background on MSVC destructors208  // ==============================209  //210  // Both Itanium and MSVC ABIs have destructor variants.  The variant names211  // roughly correspond in the following way:212  //   Itanium       Microsoft213  //   Base       -> no name, just ~Class214  //   Complete   -> vbase destructor215  //   Deleting   -> scalar deleting destructor216  //                 vector deleting destructor217  //218  // The base and complete destructors are the same as in Itanium, although the219  // complete destructor does not accept a VTT parameter when there are virtual220  // bases.  A separate mechanism involving vtordisps is used to ensure that221  // virtual methods of destroyed subobjects are not called.222  //223  // The deleting destructors accept an i32 bitfield as a second parameter.  Bit224  // 1 indicates if the memory should be deleted.  Bit 2 indicates if the this225  // pointer points to an array.  The scalar deleting destructor assumes that226  // bit 2 is zero, and therefore does not contain a loop.227  //228  // For virtual destructors, only one entry is reserved in the vftable, and it229  // always points to the vector deleting destructor.  The vector deleting230  // destructor is the most general, so it can be used to destroy objects in231  // place, delete single heap objects, or delete arrays.232  //233  // A TU defining a non-inline destructor is only guaranteed to emit a base234  // destructor, and all of the other variants are emitted on an as-needed basis235  // in COMDATs.  Because a non-base destructor can be emitted in a TU that236  // lacks a definition for the destructor, non-base destructors must always237  // delegate to or alias the base destructor.238 239  AddedStructorArgCounts240  buildStructorSignature(GlobalDecl GD,241                         SmallVectorImpl<CanQualType> &ArgTys) override;242 243  /// Non-base dtors should be emitted as delegating thunks in this ABI.244  bool useThunkForDtorVariant(const CXXDestructorDecl *Dtor,245                              CXXDtorType DT) const override {246    return DT != Dtor_Base;247  }248 249  void setCXXDestructorDLLStorage(llvm::GlobalValue *GV,250                                  const CXXDestructorDecl *Dtor,251                                  CXXDtorType DT) const override;252 253  llvm::GlobalValue::LinkageTypes254  getCXXDestructorLinkage(GVALinkage Linkage, const CXXDestructorDecl *Dtor,255                          CXXDtorType DT) const override;256 257  void EmitCXXDestructors(const CXXDestructorDecl *D) override;258 259  const CXXRecordDecl *getThisArgumentTypeForMethod(GlobalDecl GD) override {260    auto *MD = cast<CXXMethodDecl>(GD.getDecl());261 262    if (MD->isVirtual()) {263      GlobalDecl LookupGD = GD;264      if (const auto *DD = dyn_cast<CXXDestructorDecl>(MD)) {265        // Complete dtors take a pointer to the complete object,266        // thus don't need adjustment.267        if (GD.getDtorType() == Dtor_Complete)268          return MD->getParent();269 270        // There's only Dtor_Deleting in vftable but it shares the this271        // adjustment with the base one, so look up the deleting one instead.272        LookupGD = GlobalDecl(DD, Dtor_Deleting);273      }274      MethodVFTableLocation ML =275          CGM.getMicrosoftVTableContext().getMethodVFTableLocation(LookupGD);276 277      // The vbases might be ordered differently in the final overrider object278      // and the complete object, so the "this" argument may sometimes point to279      // memory that has no particular type (e.g. past the complete object).280      // In this case, we just use a generic pointer type.281      // FIXME: might want to have a more precise type in the non-virtual282      // multiple inheritance case.283      if (ML.VBase || !ML.VFPtrOffset.isZero())284        return nullptr;285    }286    return MD->getParent();287  }288 289  Address290  adjustThisArgumentForVirtualFunctionCall(CodeGenFunction &CGF, GlobalDecl GD,291                                           Address This,292                                           bool VirtualCall) override;293 294  void addImplicitStructorParams(CodeGenFunction &CGF, QualType &ResTy,295                                 FunctionArgList &Params) override;296 297  void EmitInstanceFunctionProlog(CodeGenFunction &CGF) override;298 299  AddedStructorArgs getImplicitConstructorArgs(CodeGenFunction &CGF,300                                               const CXXConstructorDecl *D,301                                               CXXCtorType Type,302                                               bool ForVirtualBase,303                                               bool Delegating) override;304 305  llvm::Value *getCXXDestructorImplicitParam(CodeGenFunction &CGF,306                                             const CXXDestructorDecl *DD,307                                             CXXDtorType Type,308                                             bool ForVirtualBase,309                                             bool Delegating) override;310 311  void EmitDestructorCall(CodeGenFunction &CGF, const CXXDestructorDecl *DD,312                          CXXDtorType Type, bool ForVirtualBase,313                          bool Delegating, Address This,314                          QualType ThisTy) override;315 316  void emitVTableTypeMetadata(const VPtrInfo &Info, const CXXRecordDecl *RD,317                              llvm::GlobalVariable *VTable);318 319  void emitVTableDefinitions(CodeGenVTables &CGVT,320                             const CXXRecordDecl *RD) override;321 322  bool isVirtualOffsetNeededForVTableField(CodeGenFunction &CGF,323                                           CodeGenFunction::VPtr Vptr) override;324 325  /// Don't initialize vptrs if dynamic class326  /// is marked with the 'novtable' attribute.327  bool doStructorsInitializeVPtrs(const CXXRecordDecl *VTableClass) override {328    return !VTableClass->hasAttr<MSNoVTableAttr>();329  }330 331  llvm::Constant *332  getVTableAddressPoint(BaseSubobject Base,333                        const CXXRecordDecl *VTableClass) override;334 335  llvm::Value *getVTableAddressPointInStructor(336      CodeGenFunction &CGF, const CXXRecordDecl *VTableClass,337      BaseSubobject Base, const CXXRecordDecl *NearestVBase) override;338 339  llvm::GlobalVariable *getAddrOfVTable(const CXXRecordDecl *RD,340                                        CharUnits VPtrOffset) override;341 342  CGCallee getVirtualFunctionPointer(CodeGenFunction &CGF, GlobalDecl GD,343                                     Address This, llvm::Type *Ty,344                                     SourceLocation Loc) override;345 346  llvm::Value *347  EmitVirtualDestructorCall(CodeGenFunction &CGF, const CXXDestructorDecl *Dtor,348                            CXXDtorType DtorType, Address This,349                            DeleteOrMemberCallExpr E,350                            llvm::CallBase **CallOrInvoke) override;351 352  void adjustCallArgsForDestructorThunk(CodeGenFunction &CGF, GlobalDecl GD,353                                        CallArgList &CallArgs) override {354    assert(GD.getDtorType() == Dtor_Deleting &&355           "Only deleting destructor thunks are available in this ABI");356    CallArgs.add(RValue::get(getStructorImplicitParamValue(CGF)),357                 getContext().IntTy);358  }359 360  void emitVirtualInheritanceTables(const CXXRecordDecl *RD) override;361 362  llvm::GlobalVariable *363  getAddrOfVBTable(const VPtrInfo &VBT, const CXXRecordDecl *RD,364                   llvm::GlobalVariable::LinkageTypes Linkage);365 366  llvm::GlobalVariable *367  getAddrOfVirtualDisplacementMap(const CXXRecordDecl *SrcRD,368                                  const CXXRecordDecl *DstRD) {369    SmallString<256> OutName;370    llvm::raw_svector_ostream Out(OutName);371    getMangleContext().mangleCXXVirtualDisplacementMap(SrcRD, DstRD, Out);372    StringRef MangledName = OutName.str();373 374    if (auto *VDispMap = CGM.getModule().getNamedGlobal(MangledName))375      return VDispMap;376 377    MicrosoftVTableContext &VTContext = CGM.getMicrosoftVTableContext();378    unsigned NumEntries = 1 + SrcRD->getNumVBases();379    SmallVector<llvm::Constant *, 4> Map(NumEntries,380                                         llvm::PoisonValue::get(CGM.IntTy));381    Map[0] = llvm::ConstantInt::get(CGM.IntTy, 0);382    bool AnyDifferent = false;383    for (const auto &I : SrcRD->vbases()) {384      const CXXRecordDecl *VBase = I.getType()->getAsCXXRecordDecl();385      if (!DstRD->isVirtuallyDerivedFrom(VBase))386        continue;387 388      unsigned SrcVBIndex = VTContext.getVBTableIndex(SrcRD, VBase);389      unsigned DstVBIndex = VTContext.getVBTableIndex(DstRD, VBase);390      Map[SrcVBIndex] = llvm::ConstantInt::get(CGM.IntTy, DstVBIndex * 4);391      AnyDifferent |= SrcVBIndex != DstVBIndex;392    }393    // This map would be useless, don't use it.394    if (!AnyDifferent)395      return nullptr;396 397    llvm::ArrayType *VDispMapTy = llvm::ArrayType::get(CGM.IntTy, Map.size());398    llvm::Constant *Init = llvm::ConstantArray::get(VDispMapTy, Map);399    llvm::GlobalValue::LinkageTypes Linkage =400        SrcRD->isExternallyVisible() && DstRD->isExternallyVisible()401            ? llvm::GlobalValue::LinkOnceODRLinkage402            : llvm::GlobalValue::InternalLinkage;403    auto *VDispMap = new llvm::GlobalVariable(404        CGM.getModule(), VDispMapTy, /*isConstant=*/true, Linkage,405        /*Initializer=*/Init, MangledName);406    return VDispMap;407  }408 409  void emitVBTableDefinition(const VPtrInfo &VBT, const CXXRecordDecl *RD,410                             llvm::GlobalVariable *GV) const;411 412  void setThunkLinkage(llvm::Function *Thunk, bool ForVTable,413                       GlobalDecl GD, bool ReturnAdjustment) override {414    GVALinkage Linkage =415        getContext().GetGVALinkageForFunction(cast<FunctionDecl>(GD.getDecl()));416 417    if (Linkage == GVA_Internal)418      Thunk->setLinkage(llvm::GlobalValue::InternalLinkage);419    else if (ReturnAdjustment)420      Thunk->setLinkage(llvm::GlobalValue::WeakODRLinkage);421    else422      Thunk->setLinkage(llvm::GlobalValue::LinkOnceODRLinkage);423  }424 425  bool exportThunk() override { return false; }426 427  llvm::Value *performThisAdjustment(CodeGenFunction &CGF, Address This,428                                     const CXXRecordDecl * /*UnadjustedClass*/,429                                     const ThunkInfo &TI) override;430 431  llvm::Value *performReturnAdjustment(CodeGenFunction &CGF, Address Ret,432                                       const CXXRecordDecl * /*UnadjustedClass*/,433                                       const ReturnAdjustment &RA) override;434 435  void EmitThreadLocalInitFuncs(436      CodeGenModule &CGM, ArrayRef<const VarDecl *> CXXThreadLocals,437      ArrayRef<llvm::Function *> CXXThreadLocalInits,438      ArrayRef<const VarDecl *> CXXThreadLocalInitVars) override;439 440  bool usesThreadWrapperFunction(const VarDecl *VD) const override {441    return getContext().getLangOpts().isCompatibleWithMSVC(442               LangOptions::MSVC2019_5) &&443           CGM.getCodeGenOpts().TlsGuards &&444           (!isEmittedWithConstantInitializer(VD) || mayNeedDestruction(VD));445  }446  LValue EmitThreadLocalVarDeclLValue(CodeGenFunction &CGF, const VarDecl *VD,447                                      QualType LValType) override;448 449  void EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D,450                       llvm::GlobalVariable *DeclPtr,451                       bool PerformInit) override;452  void registerGlobalDtor(CodeGenFunction &CGF, const VarDecl &D,453                          llvm::FunctionCallee Dtor,454                          llvm::Constant *Addr) override;455 456  // ==== Notes on array cookies =========457  //458  // MSVC seems to only use cookies when the class has a destructor; a459  // two-argument usual array deallocation function isn't sufficient.460  //461  // For example, this code prints "100" and "1":462  //   struct A {463  //     char x;464  //     void *operator new[](size_t sz) {465  //       printf("%u\n", sz);466  //       return malloc(sz);467  //     }468  //     void operator delete[](void *p, size_t sz) {469  //       printf("%u\n", sz);470  //       free(p);471  //     }472  //   };473  //   int main() {474  //     A *p = new A[100];475  //     delete[] p;476  //   }477  // Whereas it prints "104" and "104" if you give A a destructor.478 479  bool requiresArrayCookie(const CXXDeleteExpr *expr,480                           QualType elementType) override;481  bool requiresArrayCookie(const CXXNewExpr *expr) override;482  CharUnits getArrayCookieSizeImpl(QualType type) override;483  Address InitializeArrayCookie(CodeGenFunction &CGF,484                                Address NewPtr,485                                llvm::Value *NumElements,486                                const CXXNewExpr *expr,487                                QualType ElementType) override;488  llvm::Value *readArrayCookieImpl(CodeGenFunction &CGF,489                                   Address allocPtr,490                                   CharUnits cookieSize) override;491 492  friend struct MSRTTIBuilder;493 494  bool isImageRelative() const {495    return CGM.getTarget().getPointerWidth(LangAS::Default) == 64;496  }497 498  // 5 routines for constructing the llvm types for MS RTTI structs.499  llvm::StructType *getTypeDescriptorType(StringRef TypeInfoString) {500    llvm::SmallString<32> TDTypeName("rtti.TypeDescriptor");501    TDTypeName += llvm::utostr(TypeInfoString.size());502    llvm::StructType *&TypeDescriptorType =503        TypeDescriptorTypeMap[TypeInfoString.size()];504    if (TypeDescriptorType)505      return TypeDescriptorType;506    llvm::Type *FieldTypes[] = {507        CGM.Int8PtrPtrTy,508        CGM.Int8PtrTy,509        llvm::ArrayType::get(CGM.Int8Ty, TypeInfoString.size() + 1)};510    TypeDescriptorType =511        llvm::StructType::create(CGM.getLLVMContext(), FieldTypes, TDTypeName);512    return TypeDescriptorType;513  }514 515  llvm::Type *getImageRelativeType(llvm::Type *PtrType) {516    if (!isImageRelative())517      return PtrType;518    return CGM.IntTy;519  }520 521  llvm::StructType *getBaseClassDescriptorType() {522    if (BaseClassDescriptorType)523      return BaseClassDescriptorType;524    llvm::Type *FieldTypes[] = {525        getImageRelativeType(CGM.Int8PtrTy),526        CGM.IntTy,527        CGM.IntTy,528        CGM.IntTy,529        CGM.IntTy,530        CGM.IntTy,531        getImageRelativeType(CGM.DefaultPtrTy),532    };533    BaseClassDescriptorType = llvm::StructType::create(534        CGM.getLLVMContext(), FieldTypes, "rtti.BaseClassDescriptor");535    return BaseClassDescriptorType;536  }537 538  llvm::StructType *getClassHierarchyDescriptorType() {539    if (ClassHierarchyDescriptorType)540      return ClassHierarchyDescriptorType;541    // Forward-declare RTTIClassHierarchyDescriptor to break a cycle.542    llvm::Type *FieldTypes[] = {CGM.IntTy, CGM.IntTy, CGM.IntTy,543                                getImageRelativeType(CGM.DefaultPtrTy)};544    ClassHierarchyDescriptorType =545        llvm::StructType::create(FieldTypes, "rtti.ClassHierarchyDescriptor");546    return ClassHierarchyDescriptorType;547  }548 549  llvm::StructType *getCompleteObjectLocatorType() {550    if (CompleteObjectLocatorType)551      return CompleteObjectLocatorType;552    llvm::Type *FieldTypes[] = {553        CGM.IntTy,554        CGM.IntTy,555        CGM.IntTy,556        getImageRelativeType(CGM.Int8PtrTy),557        getImageRelativeType(CGM.DefaultPtrTy),558        getImageRelativeType(CGM.VoidTy),559    };560    llvm::ArrayRef<llvm::Type *> FieldTypesRef(FieldTypes);561    if (!isImageRelative())562      FieldTypesRef = FieldTypesRef.drop_back();563    CompleteObjectLocatorType =564        llvm::StructType::create(FieldTypesRef, "rtti.CompleteObjectLocator");565    return CompleteObjectLocatorType;566  }567 568  llvm::GlobalVariable *getImageBase() {569    StringRef Name = "__ImageBase";570    if (llvm::GlobalVariable *GV = CGM.getModule().getNamedGlobal(Name))571      return GV;572 573    auto *GV = new llvm::GlobalVariable(CGM.getModule(), CGM.Int8Ty,574                                        /*isConstant=*/true,575                                        llvm::GlobalValue::ExternalLinkage,576                                        /*Initializer=*/nullptr, Name);577    CGM.setDSOLocal(GV);578    return GV;579  }580 581  llvm::Constant *getImageRelativeConstant(llvm::Constant *PtrVal) {582    if (!isImageRelative())583      return PtrVal;584 585    if (PtrVal->isNullValue())586      return llvm::Constant::getNullValue(CGM.IntTy);587 588    llvm::Constant *ImageBaseAsInt =589        llvm::ConstantExpr::getPtrToInt(getImageBase(), CGM.IntPtrTy);590    llvm::Constant *PtrValAsInt =591        llvm::ConstantExpr::getPtrToInt(PtrVal, CGM.IntPtrTy);592    llvm::Constant *Diff =593        llvm::ConstantExpr::getSub(PtrValAsInt, ImageBaseAsInt,594                                   /*HasNUW=*/true, /*HasNSW=*/true);595    return llvm::ConstantExpr::getTrunc(Diff, CGM.IntTy);596  }597 598private:599  MicrosoftMangleContext &getMangleContext() {600    return cast<MicrosoftMangleContext>(CodeGen::CGCXXABI::getMangleContext());601  }602 603  llvm::Constant *getZeroInt() {604    return llvm::ConstantInt::get(CGM.IntTy, 0);605  }606 607  llvm::Constant *getAllOnesInt() {608    return  llvm::Constant::getAllOnesValue(CGM.IntTy);609  }610 611  CharUnits getVirtualFunctionPrologueThisAdjustment(GlobalDecl GD) override;612 613  void614  GetNullMemberPointerFields(const MemberPointerType *MPT,615                             llvm::SmallVectorImpl<llvm::Constant *> &fields);616 617  /// Shared code for virtual base adjustment.  Returns the offset from618  /// the vbptr to the virtual base.  Optionally returns the address of the619  /// vbptr itself.620  llvm::Value *GetVBaseOffsetFromVBPtr(CodeGenFunction &CGF,621                                       Address Base,622                                       llvm::Value *VBPtrOffset,623                                       llvm::Value *VBTableOffset,624                                       llvm::Value **VBPtr = nullptr);625 626  llvm::Value *GetVBaseOffsetFromVBPtr(CodeGenFunction &CGF,627                                       Address Base,628                                       int32_t VBPtrOffset,629                                       int32_t VBTableOffset,630                                       llvm::Value **VBPtr = nullptr) {631    assert(VBTableOffset % 4 == 0 && "should be byte offset into table of i32s");632    llvm::Value *VBPOffset = llvm::ConstantInt::get(CGM.IntTy, VBPtrOffset),633                *VBTOffset = llvm::ConstantInt::get(CGM.IntTy, VBTableOffset);634    return GetVBaseOffsetFromVBPtr(CGF, Base, VBPOffset, VBTOffset, VBPtr);635  }636 637  std::tuple<Address, llvm::Value *, const CXXRecordDecl *>638  performBaseAdjustment(CodeGenFunction &CGF, Address Value,639                        QualType SrcRecordTy);640 641  /// Performs a full virtual base adjustment.  Used to dereference642  /// pointers to members of virtual bases.643  llvm::Value *AdjustVirtualBase(CodeGenFunction &CGF, const Expr *E,644                                 const CXXRecordDecl *RD, Address Base,645                                 llvm::Value *VirtualBaseAdjustmentOffset,646                                 llvm::Value *VBPtrOffset /* optional */);647 648  /// Emits a full member pointer with the fields common to data and649  /// function member pointers.650  llvm::Constant *EmitFullMemberPointer(llvm::Constant *FirstField,651                                        bool IsMemberFunction,652                                        const CXXRecordDecl *RD,653                                        CharUnits NonVirtualBaseAdjustment,654                                        unsigned VBTableIndex);655 656  bool MemberPointerConstantIsNull(const MemberPointerType *MPT,657                                   llvm::Constant *MP);658 659  /// - Initialize all vbptrs of 'this' with RD as the complete type.660  void EmitVBPtrStores(CodeGenFunction &CGF, const CXXRecordDecl *RD);661 662  /// Caching wrapper around VBTableBuilder::enumerateVBTables().663  const VBTableGlobals &enumerateVBTables(const CXXRecordDecl *RD);664 665  /// Generate a thunk for calling a virtual member function MD.666  llvm::Function *EmitVirtualMemPtrThunk(const CXXMethodDecl *MD,667                                         const MethodVFTableLocation &ML);668 669  llvm::Constant *EmitMemberDataPointer(const CXXRecordDecl *RD,670                                        CharUnits offset);671 672public:673  llvm::Type *ConvertMemberPointerType(const MemberPointerType *MPT) override;674 675  bool isZeroInitializable(const MemberPointerType *MPT) override;676 677  bool isMemberPointerConvertible(const MemberPointerType *MPT) const override {678    const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();679    return RD->hasAttr<MSInheritanceAttr>();680  }681 682  llvm::Constant *EmitNullMemberPointer(const MemberPointerType *MPT) override;683 684  llvm::Constant *EmitMemberDataPointer(const MemberPointerType *MPT,685                                        CharUnits offset) override;686  llvm::Constant *EmitMemberFunctionPointer(const CXXMethodDecl *MD) override;687  llvm::Constant *EmitMemberPointer(const APValue &MP, QualType MPT) override;688 689  llvm::Value *EmitMemberPointerComparison(CodeGenFunction &CGF,690                                           llvm::Value *L,691                                           llvm::Value *R,692                                           const MemberPointerType *MPT,693                                           bool Inequality) override;694 695  llvm::Value *EmitMemberPointerIsNotNull(CodeGenFunction &CGF,696                                          llvm::Value *MemPtr,697                                          const MemberPointerType *MPT) override;698 699  llvm::Value *EmitMemberDataPointerAddress(CodeGenFunction &CGF, const Expr *E,700                                            Address Base, llvm::Value *MemPtr,701                                            const MemberPointerType *MPT,702                                            bool IsInBounds) override;703 704  llvm::Value *EmitNonNullMemberPointerConversion(705      const MemberPointerType *SrcTy, const MemberPointerType *DstTy,706      CastKind CK, CastExpr::path_const_iterator PathBegin,707      CastExpr::path_const_iterator PathEnd, llvm::Value *Src,708      CGBuilderTy &Builder);709 710  llvm::Value *EmitMemberPointerConversion(CodeGenFunction &CGF,711                                           const CastExpr *E,712                                           llvm::Value *Src) override;713 714  llvm::Constant *EmitMemberPointerConversion(const CastExpr *E,715                                              llvm::Constant *Src) override;716 717  llvm::Constant *EmitMemberPointerConversion(718      const MemberPointerType *SrcTy, const MemberPointerType *DstTy,719      CastKind CK, CastExpr::path_const_iterator PathBegin,720      CastExpr::path_const_iterator PathEnd, llvm::Constant *Src);721 722  CGCallee723  EmitLoadOfMemberFunctionPointer(CodeGenFunction &CGF, const Expr *E,724                                  Address This, llvm::Value *&ThisPtrForCall,725                                  llvm::Value *MemPtr,726                                  const MemberPointerType *MPT) override;727 728  void emitCXXStructor(GlobalDecl GD) override;729 730  llvm::StructType *getCatchableTypeType() {731    if (CatchableTypeType)732      return CatchableTypeType;733    llvm::Type *FieldTypes[] = {734        CGM.IntTy,                           // Flags735        getImageRelativeType(CGM.Int8PtrTy), // TypeDescriptor736        CGM.IntTy,                           // NonVirtualAdjustment737        CGM.IntTy,                           // OffsetToVBPtr738        CGM.IntTy,                           // VBTableIndex739        CGM.IntTy,                           // Size740        getImageRelativeType(CGM.Int8PtrTy)  // CopyCtor741    };742    CatchableTypeType = llvm::StructType::create(743        CGM.getLLVMContext(), FieldTypes, "eh.CatchableType");744    return CatchableTypeType;745  }746 747  llvm::StructType *getCatchableTypeArrayType(uint32_t NumEntries) {748    llvm::StructType *&CatchableTypeArrayType =749        CatchableTypeArrayTypeMap[NumEntries];750    if (CatchableTypeArrayType)751      return CatchableTypeArrayType;752 753    llvm::SmallString<23> CTATypeName("eh.CatchableTypeArray.");754    CTATypeName += llvm::utostr(NumEntries);755    llvm::Type *CTType = getImageRelativeType(CGM.DefaultPtrTy);756    llvm::Type *FieldTypes[] = {757        CGM.IntTy,                               // NumEntries758        llvm::ArrayType::get(CTType, NumEntries) // CatchableTypes759    };760    CatchableTypeArrayType =761        llvm::StructType::create(CGM.getLLVMContext(), FieldTypes, CTATypeName);762    return CatchableTypeArrayType;763  }764 765  llvm::StructType *getThrowInfoType() {766    if (ThrowInfoType)767      return ThrowInfoType;768    llvm::Type *FieldTypes[] = {769        CGM.IntTy,                           // Flags770        getImageRelativeType(CGM.Int8PtrTy), // CleanupFn771        getImageRelativeType(CGM.Int8PtrTy), // ForwardCompat772        getImageRelativeType(CGM.Int8PtrTy)  // CatchableTypeArray773    };774    ThrowInfoType = llvm::StructType::create(CGM.getLLVMContext(), FieldTypes,775                                             "eh.ThrowInfo");776    return ThrowInfoType;777  }778 779  llvm::FunctionCallee getThrowFn() {780    // _CxxThrowException is passed an exception object and a ThrowInfo object781    // which describes the exception.782    llvm::Type *Args[] = {CGM.Int8PtrTy, CGM.DefaultPtrTy};783    llvm::FunctionType *FTy =784        llvm::FunctionType::get(CGM.VoidTy, Args, /*isVarArg=*/false);785    llvm::FunctionCallee Throw =786        CGM.CreateRuntimeFunction(FTy, "_CxxThrowException");787    // _CxxThrowException is stdcall on 32-bit x86 platforms.788    if (CGM.getTarget().getTriple().getArch() == llvm::Triple::x86) {789      if (auto *Fn = dyn_cast<llvm::Function>(Throw.getCallee()))790        Fn->setCallingConv(llvm::CallingConv::X86_StdCall);791    }792    return Throw;793  }794 795  llvm::Function *getAddrOfCXXCtorClosure(const CXXConstructorDecl *CD,796                                          CXXCtorType CT);797 798  llvm::Constant *getCatchableType(QualType T,799                                   uint32_t NVOffset = 0,800                                   int32_t VBPtrOffset = -1,801                                   uint32_t VBIndex = 0);802 803  llvm::GlobalVariable *getCatchableTypeArray(QualType T);804 805  llvm::GlobalVariable *getThrowInfo(QualType T) override;806 807  std::pair<llvm::Value *, const CXXRecordDecl *>808  LoadVTablePtr(CodeGenFunction &CGF, Address This,809                const CXXRecordDecl *RD) override;810 811  bool812  isPermittedToBeHomogeneousAggregate(const CXXRecordDecl *RD) const override;813 814private:815  typedef std::pair<const CXXRecordDecl *, CharUnits> VFTableIdTy;816  typedef llvm::DenseMap<VFTableIdTy, llvm::GlobalVariable *> VTablesMapTy;817  typedef llvm::DenseMap<VFTableIdTy, llvm::GlobalValue *> VFTablesMapTy;818  /// All the vftables that have been referenced.819  VFTablesMapTy VFTablesMap;820  VTablesMapTy VTablesMap;821 822  /// This set holds the record decls we've deferred vtable emission for.823  llvm::SmallPtrSet<const CXXRecordDecl *, 4> DeferredVFTables;824 825 826  /// All the vbtables which have been referenced.827  llvm::DenseMap<const CXXRecordDecl *, VBTableGlobals> VBTablesMap;828 829  /// Info on the global variable used to guard initialization of static locals.830  /// The BitIndex field is only used for externally invisible declarations.831  struct GuardInfo {832    GuardInfo() = default;833    llvm::GlobalVariable *Guard = nullptr;834    unsigned BitIndex = 0;835  };836 837  /// Map from DeclContext to the current guard variable.  We assume that the838  /// AST is visited in source code order.839  llvm::DenseMap<const DeclContext *, GuardInfo> GuardVariableMap;840  llvm::DenseMap<const DeclContext *, GuardInfo> ThreadLocalGuardVariableMap;841  llvm::DenseMap<const DeclContext *, unsigned> ThreadSafeGuardNumMap;842 843  llvm::DenseMap<size_t, llvm::StructType *> TypeDescriptorTypeMap;844  llvm::StructType *BaseClassDescriptorType;845  llvm::StructType *ClassHierarchyDescriptorType;846  llvm::StructType *CompleteObjectLocatorType;847 848  llvm::DenseMap<QualType, llvm::GlobalVariable *> CatchableTypeArrays;849 850  llvm::StructType *CatchableTypeType;851  llvm::DenseMap<uint32_t, llvm::StructType *> CatchableTypeArrayTypeMap;852  llvm::StructType *ThrowInfoType;853};854 855}856 857CGCXXABI::RecordArgABI858MicrosoftCXXABI::getRecordArgABI(const CXXRecordDecl *RD) const {859  // Use the default C calling convention rules for things that can be passed in860  // registers, i.e. non-trivially copyable records or records marked with861  // [[trivial_abi]].862  if (RD->canPassInRegisters())863    return RAA_Default;864 865  switch (CGM.getTarget().getTriple().getArch()) {866  default:867    // FIXME: Implement for other architectures.868    return RAA_Indirect;869 870  case llvm::Triple::thumb:871    // Pass things indirectly for now because it is simple.872    // FIXME: This is incompatible with MSVC for arguments with a dtor and no873    // copy ctor.874    return RAA_Indirect;875 876  case llvm::Triple::x86: {877    // If the argument has *required* alignment greater than four bytes, pass878    // it indirectly. Prior to MSVC version 19.14, passing overaligned879    // arguments was not supported and resulted in a compiler error. In 19.14880    // and later versions, such arguments are now passed indirectly.881    TypeInfo Info =882        getContext().getTypeInfo(getContext().getCanonicalTagType(RD));883    if (Info.isAlignRequired() && Info.Align > 4)884      return RAA_Indirect;885 886    // If C++ prohibits us from making a copy, construct the arguments directly887    // into argument memory.888    return RAA_DirectInMemory;889  }890 891  case llvm::Triple::x86_64:892  case llvm::Triple::aarch64:893    return RAA_Indirect;894  }895 896  llvm_unreachable("invalid enum");897}898 899void MicrosoftCXXABI::emitVirtualObjectDelete(CodeGenFunction &CGF,900                                              const CXXDeleteExpr *DE,901                                              Address Ptr,902                                              QualType ElementType,903                                              const CXXDestructorDecl *Dtor) {904  // FIXME: Provide a source location here even though there's no905  // CXXMemberCallExpr for dtor call.906  if (!getContext().getTargetInfo().callGlobalDeleteInDeletingDtor(907          getContext().getLangOpts())) {908    bool UseGlobalDelete = DE->isGlobalDelete();909    CXXDtorType DtorType = UseGlobalDelete ? Dtor_Complete : Dtor_Deleting;910    llvm::Value *MDThis =911        EmitVirtualDestructorCall(CGF, Dtor, DtorType, Ptr, DE,912                                  /*CallOrInvoke=*/nullptr);913    if (UseGlobalDelete)914      CGF.EmitDeleteCall(DE->getOperatorDelete(), MDThis, ElementType);915  } else {916    EmitVirtualDestructorCall(CGF, Dtor, Dtor_Deleting, Ptr, DE,917                              /*CallOrInvoke=*/nullptr);918  }919}920 921void MicrosoftCXXABI::emitRethrow(CodeGenFunction &CGF, bool isNoReturn) {922  llvm::Value *Args[] = {llvm::ConstantPointerNull::get(CGM.Int8PtrTy),923                         llvm::ConstantPointerNull::get(CGM.DefaultPtrTy)};924  llvm::FunctionCallee Fn = getThrowFn();925  if (isNoReturn)926    CGF.EmitNoreturnRuntimeCallOrInvoke(Fn, Args);927  else928    CGF.EmitRuntimeCallOrInvoke(Fn, Args);929}930 931void MicrosoftCXXABI::emitBeginCatch(CodeGenFunction &CGF,932                                     const CXXCatchStmt *S) {933  // In the MS ABI, the runtime handles the copy, and the catch handler is934  // responsible for destruction.935  VarDecl *CatchParam = S->getExceptionDecl();936  llvm::BasicBlock *CatchPadBB = CGF.Builder.GetInsertBlock();937  llvm::CatchPadInst *CPI =938      cast<llvm::CatchPadInst>(CatchPadBB->getFirstNonPHIIt());939  CGF.CurrentFuncletPad = CPI;940 941  // If this is a catch-all or the catch parameter is unnamed, we don't need to942  // emit an alloca to the object.943  if (!CatchParam || !CatchParam->getDeclName()) {944    CGF.EHStack.pushCleanup<CatchRetScope>(NormalCleanup, CPI);945    return;946  }947 948  CodeGenFunction::AutoVarEmission var = CGF.EmitAutoVarAlloca(*CatchParam);949  CPI->setArgOperand(2, var.getObjectAddress(CGF).emitRawPointer(CGF));950  CGF.EHStack.pushCleanup<CatchRetScope>(NormalCleanup, CPI);951  CGF.EmitAutoVarCleanups(var);952}953 954/// We need to perform a generic polymorphic operation (like a typeid955/// or a cast), which requires an object with a vfptr.  Adjust the956/// address to point to an object with a vfptr.957std::tuple<Address, llvm::Value *, const CXXRecordDecl *>958MicrosoftCXXABI::performBaseAdjustment(CodeGenFunction &CGF, Address Value,959                                       QualType SrcRecordTy) {960  Value = Value.withElementType(CGF.Int8Ty);961  const CXXRecordDecl *SrcDecl = SrcRecordTy->getAsCXXRecordDecl();962  const ASTContext &Context = getContext();963 964  // If the class itself has a vfptr, great.  This check implicitly965  // covers non-virtual base subobjects: a class with its own virtual966  // functions would be a candidate to be a primary base.967  if (Context.getASTRecordLayout(SrcDecl).hasExtendableVFPtr())968    return std::make_tuple(Value, llvm::ConstantInt::get(CGF.Int32Ty, 0),969                           SrcDecl);970 971  // Okay, one of the vbases must have a vfptr, or else this isn't972  // actually a polymorphic class.973  const CXXRecordDecl *PolymorphicBase = nullptr;974  for (auto &Base : SrcDecl->vbases()) {975    const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();976    if (Context.getASTRecordLayout(BaseDecl).hasExtendableVFPtr()) {977      PolymorphicBase = BaseDecl;978      break;979    }980  }981  assert(PolymorphicBase && "polymorphic class has no apparent vfptr?");982 983  llvm::Value *Offset =984    GetVirtualBaseClassOffset(CGF, Value, SrcDecl, PolymorphicBase);985  llvm::Value *Ptr = CGF.Builder.CreateInBoundsGEP(986      Value.getElementType(), Value.emitRawPointer(CGF), Offset);987  CharUnits VBaseAlign =988    CGF.CGM.getVBaseAlignment(Value.getAlignment(), SrcDecl, PolymorphicBase);989  return std::make_tuple(Address(Ptr, CGF.Int8Ty, VBaseAlign), Offset,990                         PolymorphicBase);991}992 993bool MicrosoftCXXABI::shouldTypeidBeNullChecked(QualType SrcRecordTy) {994  const CXXRecordDecl *SrcDecl = SrcRecordTy->getAsCXXRecordDecl();995  return !getContext().getASTRecordLayout(SrcDecl).hasExtendableVFPtr();996}997 998static llvm::CallBase *emitRTtypeidCall(CodeGenFunction &CGF,999                                        llvm::Value *Argument) {1000  llvm::Type *ArgTypes[] = {CGF.Int8PtrTy};1001  llvm::FunctionType *FTy =1002      llvm::FunctionType::get(CGF.Int8PtrTy, ArgTypes, false);1003  llvm::Value *Args[] = {Argument};1004  llvm::FunctionCallee Fn = CGF.CGM.CreateRuntimeFunction(FTy, "__RTtypeid");1005  return CGF.EmitRuntimeCallOrInvoke(Fn, Args);1006}1007 1008void MicrosoftCXXABI::EmitBadTypeidCall(CodeGenFunction &CGF) {1009  llvm::CallBase *Call =1010      emitRTtypeidCall(CGF, llvm::Constant::getNullValue(CGM.VoidPtrTy));1011  Call->setDoesNotReturn();1012  CGF.Builder.CreateUnreachable();1013}1014 1015llvm::Value *MicrosoftCXXABI::EmitTypeid(CodeGenFunction &CGF,1016                                         QualType SrcRecordTy,1017                                         Address ThisPtr,1018                                         llvm::Type *StdTypeInfoPtrTy) {1019  std::tie(ThisPtr, std::ignore, std::ignore) =1020      performBaseAdjustment(CGF, ThisPtr, SrcRecordTy);1021  llvm::CallBase *Typeid = emitRTtypeidCall(CGF, ThisPtr.emitRawPointer(CGF));1022  return CGF.Builder.CreateBitCast(Typeid, StdTypeInfoPtrTy);1023}1024 1025bool MicrosoftCXXABI::shouldDynamicCastCallBeNullChecked(bool SrcIsPtr,1026                                                         QualType SrcRecordTy) {1027  const CXXRecordDecl *SrcDecl = SrcRecordTy->getAsCXXRecordDecl();1028  return SrcIsPtr &&1029         !getContext().getASTRecordLayout(SrcDecl).hasExtendableVFPtr();1030}1031 1032llvm::Value *MicrosoftCXXABI::emitDynamicCastCall(1033    CodeGenFunction &CGF, Address This, QualType SrcRecordTy, QualType DestTy,1034    QualType DestRecordTy, llvm::BasicBlock *CastEnd) {1035  llvm::Value *SrcRTTI =1036      CGF.CGM.GetAddrOfRTTIDescriptor(SrcRecordTy.getUnqualifiedType());1037  llvm::Value *DestRTTI =1038      CGF.CGM.GetAddrOfRTTIDescriptor(DestRecordTy.getUnqualifiedType());1039 1040  llvm::Value *Offset;1041  std::tie(This, Offset, std::ignore) =1042      performBaseAdjustment(CGF, This, SrcRecordTy);1043  llvm::Value *ThisPtr = This.emitRawPointer(CGF);1044  Offset = CGF.Builder.CreateTrunc(Offset, CGF.Int32Ty);1045 1046  // PVOID __RTDynamicCast(1047  //   PVOID inptr,1048  //   LONG VfDelta,1049  //   PVOID SrcType,1050  //   PVOID TargetType,1051  //   BOOL isReference)1052  llvm::Type *ArgTypes[] = {CGF.Int8PtrTy, CGF.Int32Ty, CGF.Int8PtrTy,1053                            CGF.Int8PtrTy, CGF.Int32Ty};1054  llvm::FunctionCallee Function = CGF.CGM.CreateRuntimeFunction(1055      llvm::FunctionType::get(CGF.Int8PtrTy, ArgTypes, false),1056      "__RTDynamicCast");1057  llvm::Value *Args[] = {1058      ThisPtr, Offset, SrcRTTI, DestRTTI,1059      llvm::ConstantInt::get(CGF.Int32Ty, DestTy->isReferenceType())};1060  return CGF.EmitRuntimeCallOrInvoke(Function, Args);1061}1062 1063llvm::Value *MicrosoftCXXABI::emitDynamicCastToVoid(CodeGenFunction &CGF,1064                                                    Address Value,1065                                                    QualType SrcRecordTy) {1066  std::tie(Value, std::ignore, std::ignore) =1067      performBaseAdjustment(CGF, Value, SrcRecordTy);1068 1069  // PVOID __RTCastToVoid(1070  //   PVOID inptr)1071  llvm::Type *ArgTypes[] = {CGF.Int8PtrTy};1072  llvm::FunctionCallee Function = CGF.CGM.CreateRuntimeFunction(1073      llvm::FunctionType::get(CGF.Int8PtrTy, ArgTypes, false),1074      "__RTCastToVoid");1075  llvm::Value *Args[] = {Value.emitRawPointer(CGF)};1076  return CGF.EmitRuntimeCall(Function, Args);1077}1078 1079bool MicrosoftCXXABI::EmitBadCastCall(CodeGenFunction &CGF) {1080  return false;1081}1082 1083llvm::Value *MicrosoftCXXABI::GetVirtualBaseClassOffset(1084    CodeGenFunction &CGF, Address This, const CXXRecordDecl *ClassDecl,1085    const CXXRecordDecl *BaseClassDecl) {1086  const ASTContext &Context = getContext();1087  int64_t VBPtrChars =1088      Context.getASTRecordLayout(ClassDecl).getVBPtrOffset().getQuantity();1089  llvm::Value *VBPtrOffset = llvm::ConstantInt::get(CGM.PtrDiffTy, VBPtrChars);1090  CharUnits IntSize = Context.getTypeSizeInChars(Context.IntTy);1091  CharUnits VBTableChars =1092      IntSize *1093      CGM.getMicrosoftVTableContext().getVBTableIndex(ClassDecl, BaseClassDecl);1094  llvm::Value *VBTableOffset =1095      llvm::ConstantInt::get(CGM.IntTy, VBTableChars.getQuantity());1096 1097  llvm::Value *VBPtrToNewBase =1098      GetVBaseOffsetFromVBPtr(CGF, This, VBPtrOffset, VBTableOffset);1099  VBPtrToNewBase =1100      CGF.Builder.CreateSExtOrBitCast(VBPtrToNewBase, CGM.PtrDiffTy);1101  return CGF.Builder.CreateNSWAdd(VBPtrOffset, VBPtrToNewBase);1102}1103 1104bool MicrosoftCXXABI::HasThisReturn(GlobalDecl GD) const {1105  return isa<CXXConstructorDecl>(GD.getDecl());1106}1107 1108static bool isDeletingDtor(GlobalDecl GD) {1109  return isa<CXXDestructorDecl>(GD.getDecl()) &&1110         GD.getDtorType() == Dtor_Deleting;1111}1112 1113bool MicrosoftCXXABI::hasMostDerivedReturn(GlobalDecl GD) const {1114  return isDeletingDtor(GD);1115}1116 1117static bool isTrivialForMSVC(const CXXRecordDecl *RD, QualType Ty,1118                             CodeGenModule &CGM) {1119  // On AArch64, HVAs that can be passed in registers can also be returned1120  // in registers. (Note this is using the MSVC definition of an HVA; see1121  // isPermittedToBeHomogeneousAggregate().)1122  const Type *Base = nullptr;1123  uint64_t NumElts = 0;1124  if (CGM.getTarget().getTriple().isAArch64() &&1125      CGM.getABIInfo().isHomogeneousAggregate(Ty, Base, NumElts) &&1126      isa<VectorType>(Base)) {1127    return true;1128  }1129 1130  // We use the C++14 definition of an aggregate, so we also1131  // check for:1132  //   No private or protected non static data members.1133  //   No base classes1134  //   No virtual functions1135  // Additionally, we need to ensure that there is a trivial copy assignment1136  // operator, a trivial destructor, no user-provided constructors and no1137  // deleted copy assignment operator.1138 1139  // We need to cover two cases when checking for a deleted copy assignment1140  // operator.1141  //1142  // struct S { int& r; };1143  // The above will have an implicit copy assignment operator that is deleted1144  // and there will not be a `CXXMethodDecl` for the copy assignment operator.1145  // This is handled by the `needsImplicitCopyAssignment()` check below.1146  //1147  // struct S { S& operator=(const S&) = delete; int i; };1148  // The above will not have an implicit copy assignment operator that is1149  // deleted but there is a deleted `CXXMethodDecl` for the declared copy1150  // assignment operator. This is handled by the `isDeleted()` check below.1151 1152  if (RD->hasProtectedFields() || RD->hasPrivateFields())1153    return false;1154  if (RD->getNumBases() > 0)1155    return false;1156  if (RD->isPolymorphic())1157    return false;1158  if (RD->hasNonTrivialCopyAssignment())1159    return false;1160  if (RD->needsImplicitCopyAssignment() && !RD->hasSimpleCopyAssignment())1161    return false;1162  for (const Decl *D : RD->decls()) {1163    if (auto *Ctor = dyn_cast<CXXConstructorDecl>(D)) {1164      if (Ctor->isUserProvided())1165        return false;1166    } else if (auto *Template = dyn_cast<FunctionTemplateDecl>(D)) {1167      if (isa<CXXConstructorDecl>(Template->getTemplatedDecl()))1168        return false;1169    } else if (auto *MethodDecl = dyn_cast<CXXMethodDecl>(D)) {1170      if (MethodDecl->isCopyAssignmentOperator() && MethodDecl->isDeleted())1171        return false;1172    }1173  }1174  if (RD->hasNonTrivialDestructor())1175    return false;1176  return true;1177}1178 1179bool MicrosoftCXXABI::classifyReturnType(CGFunctionInfo &FI) const {1180  const CXXRecordDecl *RD = FI.getReturnType()->getAsCXXRecordDecl();1181  if (!RD)1182    return false;1183 1184  bool isTrivialForABI = RD->canPassInRegisters() &&1185                         isTrivialForMSVC(RD, FI.getReturnType(), CGM);1186 1187  // MSVC always returns structs indirectly from C++ instance methods.1188  bool isIndirectReturn = !isTrivialForABI || FI.isInstanceMethod();1189 1190  if (isIndirectReturn) {1191    CharUnits Align = CGM.getContext().getTypeAlignInChars(FI.getReturnType());1192    FI.getReturnInfo() = ABIArgInfo::getIndirect(1193        Align, /*AddrSpace=*/CGM.getDataLayout().getAllocaAddrSpace(),1194        /*ByVal=*/false);1195 1196    // MSVC always passes `this` before the `sret` parameter.1197    FI.getReturnInfo().setSRetAfterThis(FI.isInstanceMethod());1198 1199    // On AArch64, use the `inreg` attribute if the object is considered to not1200    // be trivially copyable, or if this is an instance method struct return.1201    FI.getReturnInfo().setInReg(CGM.getTarget().getTriple().isAArch64());1202 1203    return true;1204  }1205 1206  // Otherwise, use the C ABI rules.1207  return false;1208}1209 1210llvm::BasicBlock *1211MicrosoftCXXABI::EmitCtorCompleteObjectHandler(CodeGenFunction &CGF,1212                                               const CXXRecordDecl *RD) {1213  llvm::Value *IsMostDerivedClass = getStructorImplicitParamValue(CGF);1214  assert(IsMostDerivedClass &&1215         "ctor for a class with virtual bases must have an implicit parameter");1216  llvm::Value *IsCompleteObject =1217    CGF.Builder.CreateIsNotNull(IsMostDerivedClass, "is_complete_object");1218 1219  llvm::BasicBlock *CallVbaseCtorsBB = CGF.createBasicBlock("ctor.init_vbases");1220  llvm::BasicBlock *SkipVbaseCtorsBB = CGF.createBasicBlock("ctor.skip_vbases");1221  CGF.Builder.CreateCondBr(IsCompleteObject,1222                           CallVbaseCtorsBB, SkipVbaseCtorsBB);1223 1224  CGF.EmitBlock(CallVbaseCtorsBB);1225 1226  // Fill in the vbtable pointers here.1227  EmitVBPtrStores(CGF, RD);1228 1229  // CGF will put the base ctor calls in this basic block for us later.1230 1231  return SkipVbaseCtorsBB;1232}1233 1234llvm::BasicBlock *1235MicrosoftCXXABI::EmitDtorCompleteObjectHandler(CodeGenFunction &CGF) {1236  llvm::Value *IsMostDerivedClass = getStructorImplicitParamValue(CGF);1237  assert(IsMostDerivedClass &&1238         "ctor for a class with virtual bases must have an implicit parameter");1239  llvm::Value *IsCompleteObject =1240      CGF.Builder.CreateIsNotNull(IsMostDerivedClass, "is_complete_object");1241 1242  llvm::BasicBlock *CallVbaseDtorsBB = CGF.createBasicBlock("Dtor.dtor_vbases");1243  llvm::BasicBlock *SkipVbaseDtorsBB = CGF.createBasicBlock("Dtor.skip_vbases");1244  CGF.Builder.CreateCondBr(IsCompleteObject,1245                           CallVbaseDtorsBB, SkipVbaseDtorsBB);1246 1247  CGF.EmitBlock(CallVbaseDtorsBB);1248  // CGF will put the base dtor calls in this basic block for us later.1249 1250  return SkipVbaseDtorsBB;1251}1252 1253void MicrosoftCXXABI::initializeHiddenVirtualInheritanceMembers(1254    CodeGenFunction &CGF, const CXXRecordDecl *RD) {1255  // In most cases, an override for a vbase virtual method can adjust1256  // the "this" parameter by applying a constant offset.1257  // However, this is not enough while a constructor or a destructor of some1258  // class X is being executed if all the following conditions are met:1259  //  - X has virtual bases, (1)1260  //  - X overrides a virtual method M of a vbase Y, (2)1261  //  - X itself is a vbase of the most derived class.1262  //1263  // If (1) and (2) are true, the vtorDisp for vbase Y is a hidden member of X1264  // which holds the extra amount of "this" adjustment we must do when we use1265  // the X vftables (i.e. during X ctor or dtor).1266  // Outside the ctors and dtors, the values of vtorDisps are zero.1267 1268  const ASTRecordLayout &Layout = getContext().getASTRecordLayout(RD);1269  typedef ASTRecordLayout::VBaseOffsetsMapTy VBOffsets;1270  const VBOffsets &VBaseMap = Layout.getVBaseOffsetsMap();1271  CGBuilderTy &Builder = CGF.Builder;1272 1273  llvm::Value *Int8This = nullptr;  // Initialize lazily.1274 1275  for (const CXXBaseSpecifier &S : RD->vbases()) {1276    const CXXRecordDecl *VBase = S.getType()->getAsCXXRecordDecl();1277    auto I = VBaseMap.find(VBase);1278    assert(I != VBaseMap.end());1279    if (!I->second.hasVtorDisp())1280      continue;1281 1282    llvm::Value *VBaseOffset =1283        GetVirtualBaseClassOffset(CGF, getThisAddress(CGF), RD, VBase);1284    uint64_t ConstantVBaseOffset = I->second.VBaseOffset.getQuantity();1285 1286    // vtorDisp_for_vbase = vbptr[vbase_idx] - offsetof(RD, vbase).1287    llvm::Value *VtorDispValue = Builder.CreateSub(1288        VBaseOffset, llvm::ConstantInt::get(CGM.PtrDiffTy, ConstantVBaseOffset),1289        "vtordisp.value");1290    VtorDispValue = Builder.CreateTruncOrBitCast(VtorDispValue, CGF.Int32Ty);1291 1292    if (!Int8This)1293      Int8This = getThisValue(CGF);1294 1295    llvm::Value *VtorDispPtr =1296        Builder.CreateInBoundsGEP(CGF.Int8Ty, Int8This, VBaseOffset);1297    // vtorDisp is always the 32-bits before the vbase in the class layout.1298    VtorDispPtr = Builder.CreateConstGEP1_32(CGF.Int8Ty, VtorDispPtr, -4);1299 1300    Builder.CreateAlignedStore(VtorDispValue, VtorDispPtr,1301                               CharUnits::fromQuantity(4));1302  }1303}1304 1305static bool hasDefaultCXXMethodCC(ASTContext &Context,1306                                  const CXXMethodDecl *MD) {1307  CallingConv ExpectedCallingConv = Context.getDefaultCallingConvention(1308      /*IsVariadic=*/false, /*IsCXXMethod=*/true);1309  CallingConv ActualCallingConv =1310      MD->getType()->castAs<FunctionProtoType>()->getCallConv();1311  return ExpectedCallingConv == ActualCallingConv;1312}1313 1314void MicrosoftCXXABI::EmitCXXConstructors(const CXXConstructorDecl *D) {1315  // There's only one constructor type in this ABI.1316  CGM.EmitGlobal(GlobalDecl(D, Ctor_Complete));1317 1318  // Exported default constructors either have a simple call-site where they use1319  // the typical calling convention and have a single 'this' pointer for an1320  // argument -or- they get a wrapper function which appropriately thunks to the1321  // real default constructor.  This thunk is the default constructor closure.1322  if (D->hasAttr<DLLExportAttr>() && D->isDefaultConstructor() &&1323      D->isDefined()) {1324    if (!hasDefaultCXXMethodCC(getContext(), D) || D->getNumParams() != 0) {1325      llvm::Function *Fn = getAddrOfCXXCtorClosure(D, Ctor_DefaultClosure);1326      Fn->setLinkage(llvm::GlobalValue::WeakODRLinkage);1327      CGM.setGVProperties(Fn, D);1328    }1329  }1330}1331 1332void MicrosoftCXXABI::EmitVBPtrStores(CodeGenFunction &CGF,1333                                      const CXXRecordDecl *RD) {1334  Address This = getThisAddress(CGF);1335  This = This.withElementType(CGM.Int8Ty);1336  const ASTContext &Context = getContext();1337  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);1338 1339  const VBTableGlobals &VBGlobals = enumerateVBTables(RD);1340  for (unsigned I = 0, E = VBGlobals.VBTables->size(); I != E; ++I) {1341    const std::unique_ptr<VPtrInfo> &VBT = (*VBGlobals.VBTables)[I];1342    llvm::GlobalVariable *GV = VBGlobals.Globals[I];1343    const ASTRecordLayout &SubobjectLayout =1344        Context.getASTRecordLayout(VBT->IntroducingObject);1345    CharUnits Offs = VBT->NonVirtualOffset;1346    Offs += SubobjectLayout.getVBPtrOffset();1347    if (VBT->getVBaseWithVPtr())1348      Offs += Layout.getVBaseClassOffset(VBT->getVBaseWithVPtr());1349    Address VBPtr = CGF.Builder.CreateConstInBoundsByteGEP(This, Offs);1350    llvm::Value *GVPtr =1351        CGF.Builder.CreateConstInBoundsGEP2_32(GV->getValueType(), GV, 0, 0);1352    VBPtr = VBPtr.withElementType(GVPtr->getType());1353    CGF.Builder.CreateStore(GVPtr, VBPtr);1354  }1355}1356 1357CGCXXABI::AddedStructorArgCounts1358MicrosoftCXXABI::buildStructorSignature(GlobalDecl GD,1359                                        SmallVectorImpl<CanQualType> &ArgTys) {1360  AddedStructorArgCounts Added;1361  // TODO: 'for base' flag1362  if (isa<CXXDestructorDecl>(GD.getDecl()) &&1363      GD.getDtorType() == Dtor_Deleting) {1364    // The scalar deleting destructor takes an implicit int parameter.1365    ArgTys.push_back(getContext().IntTy);1366    ++Added.Suffix;1367  }1368  auto *CD = dyn_cast<CXXConstructorDecl>(GD.getDecl());1369  if (!CD)1370    return Added;1371 1372  // All parameters are already in place except is_most_derived, which goes1373  // after 'this' if it's variadic and last if it's not.1374 1375  const CXXRecordDecl *Class = CD->getParent();1376  const FunctionProtoType *FPT = CD->getType()->castAs<FunctionProtoType>();1377  if (Class->getNumVBases()) {1378    if (FPT->isVariadic()) {1379      ArgTys.insert(ArgTys.begin() + 1, getContext().IntTy);1380      ++Added.Prefix;1381    } else {1382      ArgTys.push_back(getContext().IntTy);1383      ++Added.Suffix;1384    }1385  }1386 1387  return Added;1388}1389 1390void MicrosoftCXXABI::setCXXDestructorDLLStorage(llvm::GlobalValue *GV,1391                                                 const CXXDestructorDecl *Dtor,1392                                                 CXXDtorType DT) const {1393  // Deleting destructor variants are never imported or exported. Give them the1394  // default storage class.1395  if (DT == Dtor_Deleting) {1396    GV->setDLLStorageClass(llvm::GlobalValue::DefaultStorageClass);1397  } else {1398    const NamedDecl *ND = Dtor;1399    CGM.setDLLImportDLLExport(GV, ND);1400  }1401}1402 1403llvm::GlobalValue::LinkageTypes MicrosoftCXXABI::getCXXDestructorLinkage(1404    GVALinkage Linkage, const CXXDestructorDecl *Dtor, CXXDtorType DT) const {1405  // Internal things are always internal, regardless of attributes. After this,1406  // we know the thunk is externally visible.1407  if (Linkage == GVA_Internal)1408    return llvm::GlobalValue::InternalLinkage;1409 1410  switch (DT) {1411  case Dtor_Base:1412    // The base destructor most closely tracks the user-declared constructor, so1413    // we delegate back to the normal declarator case.1414    return CGM.getLLVMLinkageForDeclarator(Dtor, Linkage);1415  case Dtor_Complete:1416    // The complete destructor is like an inline function, but it may be1417    // imported and therefore must be exported as well. This requires changing1418    // the linkage if a DLL attribute is present.1419    if (Dtor->hasAttr<DLLExportAttr>())1420      return llvm::GlobalValue::WeakODRLinkage;1421    if (Dtor->hasAttr<DLLImportAttr>())1422      return llvm::GlobalValue::AvailableExternallyLinkage;1423    return llvm::GlobalValue::LinkOnceODRLinkage;1424  case Dtor_Deleting:1425    // Deleting destructors are like inline functions. They have vague linkage1426    // and are emitted everywhere they are used. They are internal if the class1427    // is internal.1428    return llvm::GlobalValue::LinkOnceODRLinkage;1429  case Dtor_Unified:1430    llvm_unreachable("MS C++ ABI does not support unified dtors");1431  case Dtor_Comdat:1432    llvm_unreachable("MS C++ ABI does not support comdat dtors");1433  }1434  llvm_unreachable("invalid dtor type");1435}1436 1437void MicrosoftCXXABI::EmitCXXDestructors(const CXXDestructorDecl *D) {1438  // The TU defining a dtor is only guaranteed to emit a base destructor.  All1439  // other destructor variants are delegating thunks.1440  CGM.EmitGlobal(GlobalDecl(D, Dtor_Base));1441 1442  // If the class is dllexported, emit the complete (vbase) destructor wherever1443  // the base dtor is emitted.1444  // FIXME: To match MSVC, this should only be done when the class is exported1445  // with -fdllexport-inlines enabled.1446  if (D->getParent()->getNumVBases() > 0 && D->hasAttr<DLLExportAttr>())1447    CGM.EmitGlobal(GlobalDecl(D, Dtor_Complete));1448}1449 1450CharUnits1451MicrosoftCXXABI::getVirtualFunctionPrologueThisAdjustment(GlobalDecl GD) {1452  const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());1453 1454  if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {1455    // Complete destructors take a pointer to the complete object as a1456    // parameter, thus don't need this adjustment.1457    if (GD.getDtorType() == Dtor_Complete)1458      return CharUnits();1459 1460    // There's no Dtor_Base in vftable but it shares the this adjustment with1461    // the deleting one, so look it up instead.1462    GD = GlobalDecl(DD, Dtor_Deleting);1463  }1464 1465  MethodVFTableLocation ML =1466      CGM.getMicrosoftVTableContext().getMethodVFTableLocation(GD);1467  CharUnits Adjustment = ML.VFPtrOffset;1468 1469  // Normal virtual instance methods need to adjust from the vfptr that first1470  // defined the virtual method to the virtual base subobject, but destructors1471  // do not.  The vector deleting destructor thunk applies this adjustment for1472  // us if necessary.1473  if (isa<CXXDestructorDecl>(MD))1474    Adjustment = CharUnits::Zero();1475 1476  if (ML.VBase) {1477    const ASTRecordLayout &DerivedLayout =1478        getContext().getASTRecordLayout(MD->getParent());1479    Adjustment += DerivedLayout.getVBaseClassOffset(ML.VBase);1480  }1481 1482  return Adjustment;1483}1484 1485Address MicrosoftCXXABI::adjustThisArgumentForVirtualFunctionCall(1486    CodeGenFunction &CGF, GlobalDecl GD, Address This,1487    bool VirtualCall) {1488  if (!VirtualCall) {1489    // If the call of a virtual function is not virtual, we just have to1490    // compensate for the adjustment the virtual function does in its prologue.1491    CharUnits Adjustment = getVirtualFunctionPrologueThisAdjustment(GD);1492    if (Adjustment.isZero())1493      return This;1494 1495    This = This.withElementType(CGF.Int8Ty);1496    assert(Adjustment.isPositive());1497    return CGF.Builder.CreateConstByteGEP(This, Adjustment);1498  }1499 1500  const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());1501 1502  GlobalDecl LookupGD = GD;1503  if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {1504    // Complete dtors take a pointer to the complete object,1505    // thus don't need adjustment.1506    if (GD.getDtorType() == Dtor_Complete)1507      return This;1508 1509    // There's only Dtor_Deleting in vftable but it shares the this adjustment1510    // with the base one, so look up the deleting one instead.1511    LookupGD = GlobalDecl(DD, Dtor_Deleting);1512  }1513  MethodVFTableLocation ML =1514      CGM.getMicrosoftVTableContext().getMethodVFTableLocation(LookupGD);1515 1516  CharUnits StaticOffset = ML.VFPtrOffset;1517 1518  // Base destructors expect 'this' to point to the beginning of the base1519  // subobject, not the first vfptr that happens to contain the virtual dtor.1520  // However, we still need to apply the virtual base adjustment.1521  if (isa<CXXDestructorDecl>(MD) && GD.getDtorType() == Dtor_Base)1522    StaticOffset = CharUnits::Zero();1523 1524  Address Result = This;1525  if (ML.VBase) {1526    Result = Result.withElementType(CGF.Int8Ty);1527 1528    const CXXRecordDecl *Derived = MD->getParent();1529    const CXXRecordDecl *VBase = ML.VBase;1530    llvm::Value *VBaseOffset =1531      GetVirtualBaseClassOffset(CGF, Result, Derived, VBase);1532    llvm::Value *VBasePtr = CGF.Builder.CreateInBoundsGEP(1533        Result.getElementType(), Result.emitRawPointer(CGF), VBaseOffset);1534    CharUnits VBaseAlign =1535      CGF.CGM.getVBaseAlignment(Result.getAlignment(), Derived, VBase);1536    Result = Address(VBasePtr, CGF.Int8Ty, VBaseAlign);1537  }1538  if (!StaticOffset.isZero()) {1539    assert(StaticOffset.isPositive());1540    Result = Result.withElementType(CGF.Int8Ty);1541    if (ML.VBase) {1542      // Non-virtual adjustment might result in a pointer outside the allocated1543      // object, e.g. if the final overrider class is laid out after the virtual1544      // base that declares a method in the most derived class.1545      // FIXME: Update the code that emits this adjustment in thunks prologues.1546      Result = CGF.Builder.CreateConstByteGEP(Result, StaticOffset);1547    } else {1548      Result = CGF.Builder.CreateConstInBoundsByteGEP(Result, StaticOffset);1549    }1550  }1551  return Result;1552}1553 1554void MicrosoftCXXABI::addImplicitStructorParams(CodeGenFunction &CGF,1555                                                QualType &ResTy,1556                                                FunctionArgList &Params) {1557  ASTContext &Context = getContext();1558  const CXXMethodDecl *MD = cast<CXXMethodDecl>(CGF.CurGD.getDecl());1559  assert(isa<CXXConstructorDecl>(MD) || isa<CXXDestructorDecl>(MD));1560  if (isa<CXXConstructorDecl>(MD) && MD->getParent()->getNumVBases()) {1561    auto *IsMostDerived = ImplicitParamDecl::Create(1562        Context, /*DC=*/nullptr, CGF.CurGD.getDecl()->getLocation(),1563        &Context.Idents.get("is_most_derived"), Context.IntTy,1564        ImplicitParamKind::Other);1565    // The 'most_derived' parameter goes second if the ctor is variadic and last1566    // if it's not.  Dtors can't be variadic.1567    const FunctionProtoType *FPT = MD->getType()->castAs<FunctionProtoType>();1568    if (FPT->isVariadic())1569      Params.insert(Params.begin() + 1, IsMostDerived);1570    else1571      Params.push_back(IsMostDerived);1572    getStructorImplicitParamDecl(CGF) = IsMostDerived;1573  } else if (isDeletingDtor(CGF.CurGD)) {1574    auto *ShouldDelete = ImplicitParamDecl::Create(1575        Context, /*DC=*/nullptr, CGF.CurGD.getDecl()->getLocation(),1576        &Context.Idents.get("should_call_delete"), Context.IntTy,1577        ImplicitParamKind::Other);1578    Params.push_back(ShouldDelete);1579    getStructorImplicitParamDecl(CGF) = ShouldDelete;1580  }1581}1582 1583void MicrosoftCXXABI::EmitInstanceFunctionProlog(CodeGenFunction &CGF) {1584  // Naked functions have no prolog.1585  if (CGF.CurFuncDecl && CGF.CurFuncDecl->hasAttr<NakedAttr>())1586    return;1587 1588  // Overridden virtual methods of non-primary bases need to adjust the incoming1589  // 'this' pointer in the prologue. In this hierarchy, C::b will subtract1590  // sizeof(void*) to adjust from B* to C*:1591  //   struct A { virtual void a(); };1592  //   struct B { virtual void b(); };1593  //   struct C : A, B { virtual void b(); };1594  //1595  // Leave the value stored in the 'this' alloca unadjusted, so that the1596  // debugger sees the unadjusted value. Microsoft debuggers require this, and1597  // will apply the ThisAdjustment in the method type information.1598  // FIXME: Do something better for DWARF debuggers, which won't expect this,1599  // without making our codegen depend on debug info settings.1600  llvm::Value *This = loadIncomingCXXThis(CGF);1601  const CXXMethodDecl *MD = cast<CXXMethodDecl>(CGF.CurGD.getDecl());1602  if (!CGF.CurFuncIsThunk && MD->isVirtual()) {1603    CharUnits Adjustment = getVirtualFunctionPrologueThisAdjustment(CGF.CurGD);1604    if (!Adjustment.isZero()) {1605      assert(Adjustment.isPositive());1606      This = CGF.Builder.CreateConstInBoundsGEP1_32(CGF.Int8Ty, This,1607                                                    -Adjustment.getQuantity());1608    }1609  }1610  setCXXABIThisValue(CGF, This);1611 1612  // If this is a function that the ABI specifies returns 'this', initialize1613  // the return slot to 'this' at the start of the function.1614  //1615  // Unlike the setting of return types, this is done within the ABI1616  // implementation instead of by clients of CGCXXABI because:1617  // 1) getThisValue is currently protected1618  // 2) in theory, an ABI could implement 'this' returns some other way;1619  //    HasThisReturn only specifies a contract, not the implementation1620  if (HasThisReturn(CGF.CurGD) || hasMostDerivedReturn(CGF.CurGD))1621    CGF.Builder.CreateStore(getThisValue(CGF), CGF.ReturnValue);1622 1623  if (isa<CXXConstructorDecl>(MD) && MD->getParent()->getNumVBases()) {1624    assert(getStructorImplicitParamDecl(CGF) &&1625           "no implicit parameter for a constructor with virtual bases?");1626    getStructorImplicitParamValue(CGF)1627      = CGF.Builder.CreateLoad(1628          CGF.GetAddrOfLocalVar(getStructorImplicitParamDecl(CGF)),1629          "is_most_derived");1630  }1631 1632  if (isDeletingDtor(CGF.CurGD)) {1633    assert(getStructorImplicitParamDecl(CGF) &&1634           "no implicit parameter for a deleting destructor?");1635    getStructorImplicitParamValue(CGF)1636      = CGF.Builder.CreateLoad(1637          CGF.GetAddrOfLocalVar(getStructorImplicitParamDecl(CGF)),1638          "should_call_delete");1639  }1640}1641 1642CGCXXABI::AddedStructorArgs MicrosoftCXXABI::getImplicitConstructorArgs(1643    CodeGenFunction &CGF, const CXXConstructorDecl *D, CXXCtorType Type,1644    bool ForVirtualBase, bool Delegating) {1645  assert(Type == Ctor_Complete || Type == Ctor_Base);1646 1647  // Check if we need a 'most_derived' parameter.1648  if (!D->getParent()->getNumVBases())1649    return AddedStructorArgs{};1650 1651  // Add the 'most_derived' argument second if we are variadic or last if not.1652  const FunctionProtoType *FPT = D->getType()->castAs<FunctionProtoType>();1653  llvm::Value *MostDerivedArg;1654  if (Delegating) {1655    MostDerivedArg = getStructorImplicitParamValue(CGF);1656  } else {1657    MostDerivedArg = llvm::ConstantInt::get(CGM.Int32Ty, Type == Ctor_Complete);1658  }1659  if (FPT->isVariadic()) {1660    return AddedStructorArgs::prefix({{MostDerivedArg, getContext().IntTy}});1661  }1662  return AddedStructorArgs::suffix({{MostDerivedArg, getContext().IntTy}});1663}1664 1665llvm::Value *MicrosoftCXXABI::getCXXDestructorImplicitParam(1666    CodeGenFunction &CGF, const CXXDestructorDecl *DD, CXXDtorType Type,1667    bool ForVirtualBase, bool Delegating) {1668  return nullptr;1669}1670 1671void MicrosoftCXXABI::EmitDestructorCall(CodeGenFunction &CGF,1672                                         const CXXDestructorDecl *DD,1673                                         CXXDtorType Type, bool ForVirtualBase,1674                                         bool Delegating, Address This,1675                                         QualType ThisTy) {1676  // Use the base destructor variant in place of the complete destructor variant1677  // if the class has no virtual bases. This effectively implements some of the1678  // -mconstructor-aliases optimization, but as part of the MS C++ ABI.1679  if (Type == Dtor_Complete && DD->getParent()->getNumVBases() == 0)1680    Type = Dtor_Base;1681 1682  GlobalDecl GD(DD, Type);1683  CGCallee Callee = CGCallee::forDirect(CGM.getAddrOfCXXStructor(GD), GD);1684 1685  if (DD->isVirtual()) {1686    assert(Type != CXXDtorType::Dtor_Deleting &&1687           "The deleting destructor should only be called via a virtual call");1688    This = adjustThisArgumentForVirtualFunctionCall(CGF, GlobalDecl(DD, Type),1689                                                    This, false);1690  }1691 1692  llvm::BasicBlock *BaseDtorEndBB = nullptr;1693  if (ForVirtualBase && isa<CXXConstructorDecl>(CGF.CurCodeDecl)) {1694    BaseDtorEndBB = EmitDtorCompleteObjectHandler(CGF);1695  }1696 1697  llvm::Value *Implicit =1698      getCXXDestructorImplicitParam(CGF, DD, Type, ForVirtualBase,1699                                    Delegating); // = nullptr1700  CGF.EmitCXXDestructorCall(GD, Callee, CGF.getAsNaturalPointerTo(This, ThisTy),1701                            ThisTy,1702                            /*ImplicitParam=*/Implicit,1703                            /*ImplicitParamTy=*/QualType(), /*E=*/nullptr);1704  if (BaseDtorEndBB) {1705    // Complete object handler should continue to be the remaining1706    CGF.Builder.CreateBr(BaseDtorEndBB);1707    CGF.EmitBlock(BaseDtorEndBB);1708  }1709}1710 1711void MicrosoftCXXABI::emitVTableTypeMetadata(const VPtrInfo &Info,1712                                             const CXXRecordDecl *RD,1713                                             llvm::GlobalVariable *VTable) {1714  // Emit type metadata on vtables with LTO or IR instrumentation.1715  // In IR instrumentation, the type metadata could be used to find out vtable1716  // definitions (for type profiling) among all global variables.1717  if (!CGM.getCodeGenOpts().LTOUnit &&1718      !CGM.getCodeGenOpts().hasProfileIRInstr())1719    return;1720 1721  // TODO: Should VirtualFunctionElimination also be supported here?1722  // See similar handling in CodeGenModule::EmitVTableTypeMetadata.1723  if (CGM.getCodeGenOpts().WholeProgramVTables) {1724    llvm::DenseSet<const CXXRecordDecl *> Visited;1725    llvm::GlobalObject::VCallVisibility TypeVis =1726        CGM.GetVCallVisibilityLevel(RD, Visited);1727    if (TypeVis != llvm::GlobalObject::VCallVisibilityPublic)1728      VTable->setVCallVisibilityMetadata(TypeVis);1729  }1730 1731  // The location of the first virtual function pointer in the virtual table,1732  // aka the "address point" on Itanium. This is at offset 0 if RTTI is1733  // disabled, or sizeof(void*) if RTTI is enabled.1734  CharUnits AddressPoint =1735      getContext().getLangOpts().RTTIData1736          ? getContext().toCharUnitsFromBits(1737                getContext().getTargetInfo().getPointerWidth(LangAS::Default))1738          : CharUnits::Zero();1739 1740  if (Info.PathToIntroducingObject.empty()) {1741    CGM.AddVTableTypeMetadata(VTable, AddressPoint, RD);1742    return;1743  }1744 1745  // Add a bitset entry for the least derived base belonging to this vftable.1746  CGM.AddVTableTypeMetadata(VTable, AddressPoint,1747                            Info.PathToIntroducingObject.back());1748 1749  // Add a bitset entry for each derived class that is laid out at the same1750  // offset as the least derived base.1751  for (unsigned I = Info.PathToIntroducingObject.size() - 1; I != 0; --I) {1752    const CXXRecordDecl *DerivedRD = Info.PathToIntroducingObject[I - 1];1753    const CXXRecordDecl *BaseRD = Info.PathToIntroducingObject[I];1754 1755    const ASTRecordLayout &Layout =1756        getContext().getASTRecordLayout(DerivedRD);1757    CharUnits Offset;1758    auto VBI = Layout.getVBaseOffsetsMap().find(BaseRD);1759    if (VBI == Layout.getVBaseOffsetsMap().end())1760      Offset = Layout.getBaseClassOffset(BaseRD);1761    else1762      Offset = VBI->second.VBaseOffset;1763    if (!Offset.isZero())1764      return;1765    CGM.AddVTableTypeMetadata(VTable, AddressPoint, DerivedRD);1766  }1767 1768  // Finally do the same for the most derived class.1769  if (Info.FullOffsetInMDC.isZero())1770    CGM.AddVTableTypeMetadata(VTable, AddressPoint, RD);1771}1772 1773void MicrosoftCXXABI::emitVTableDefinitions(CodeGenVTables &CGVT,1774                                            const CXXRecordDecl *RD) {1775  MicrosoftVTableContext &VFTContext = CGM.getMicrosoftVTableContext();1776  const VPtrInfoVector &VFPtrs = VFTContext.getVFPtrOffsets(RD);1777 1778  for (const std::unique_ptr<VPtrInfo>& Info : VFPtrs) {1779    llvm::GlobalVariable *VTable = getAddrOfVTable(RD, Info->FullOffsetInMDC);1780    if (VTable->hasInitializer())1781      continue;1782 1783    const VTableLayout &VTLayout =1784      VFTContext.getVFTableLayout(RD, Info->FullOffsetInMDC);1785 1786    llvm::Constant *RTTI = nullptr;1787    if (any_of(VTLayout.vtable_components(),1788               [](const VTableComponent &VTC) { return VTC.isRTTIKind(); }))1789      RTTI = getMSCompleteObjectLocator(RD, *Info);1790 1791    ConstantInitBuilder builder(CGM);1792    auto components = builder.beginStruct();1793    CGVT.createVTableInitializer(components, VTLayout, RTTI,1794                                 VTable->hasLocalLinkage());1795    components.finishAndSetAsInitializer(VTable);1796 1797    emitVTableTypeMetadata(*Info, RD, VTable);1798  }1799}1800 1801bool MicrosoftCXXABI::isVirtualOffsetNeededForVTableField(1802    CodeGenFunction &CGF, CodeGenFunction::VPtr Vptr) {1803  return Vptr.NearestVBase != nullptr;1804}1805 1806llvm::Value *MicrosoftCXXABI::getVTableAddressPointInStructor(1807    CodeGenFunction &CGF, const CXXRecordDecl *VTableClass, BaseSubobject Base,1808    const CXXRecordDecl *NearestVBase) {1809  llvm::Constant *VTableAddressPoint = getVTableAddressPoint(Base, VTableClass);1810  if (!VTableAddressPoint) {1811    assert(Base.getBase()->getNumVBases() &&1812           !getContext().getASTRecordLayout(Base.getBase()).hasOwnVFPtr());1813  }1814  return VTableAddressPoint;1815}1816 1817static void mangleVFTableName(MicrosoftMangleContext &MangleContext,1818                              const CXXRecordDecl *RD, const VPtrInfo &VFPtr,1819                              SmallString<256> &Name) {1820  llvm::raw_svector_ostream Out(Name);1821  MangleContext.mangleCXXVFTable(RD, VFPtr.MangledPath, Out);1822}1823 1824llvm::Constant *1825MicrosoftCXXABI::getVTableAddressPoint(BaseSubobject Base,1826                                       const CXXRecordDecl *VTableClass) {1827  (void)getAddrOfVTable(VTableClass, Base.getBaseOffset());1828  VFTableIdTy ID(VTableClass, Base.getBaseOffset());1829  return VFTablesMap[ID];1830}1831 1832llvm::GlobalVariable *MicrosoftCXXABI::getAddrOfVTable(const CXXRecordDecl *RD,1833                                                       CharUnits VPtrOffset) {1834  // getAddrOfVTable may return 0 if asked to get an address of a vtable which1835  // shouldn't be used in the given record type. We want to cache this result in1836  // VFTablesMap, thus a simple zero check is not sufficient.1837 1838  VFTableIdTy ID(RD, VPtrOffset);1839  auto [I, Inserted] = VTablesMap.try_emplace(ID);1840  if (!Inserted)1841    return I->second;1842 1843  llvm::GlobalVariable *&VTable = I->second;1844 1845  MicrosoftVTableContext &VTContext = CGM.getMicrosoftVTableContext();1846  const VPtrInfoVector &VFPtrs = VTContext.getVFPtrOffsets(RD);1847 1848  if (DeferredVFTables.insert(RD).second) {1849    // We haven't processed this record type before.1850    // Queue up this vtable for possible deferred emission.1851    CGM.addDeferredVTable(RD);1852 1853#ifndef NDEBUG1854    // Create all the vftables at once in order to make sure each vftable has1855    // a unique mangled name.1856    llvm::StringSet<> ObservedMangledNames;1857    for (const auto &VFPtr : VFPtrs) {1858      SmallString<256> Name;1859      mangleVFTableName(getMangleContext(), RD, *VFPtr, Name);1860      if (!ObservedMangledNames.insert(Name.str()).second)1861        llvm_unreachable("Already saw this mangling before?");1862    }1863#endif1864  }1865 1866  const std::unique_ptr<VPtrInfo> *VFPtrI =1867      llvm::find_if(VFPtrs, [&](const std::unique_ptr<VPtrInfo> &VPI) {1868        return VPI->FullOffsetInMDC == VPtrOffset;1869      });1870  if (VFPtrI == VFPtrs.end()) {1871    VFTablesMap[ID] = nullptr;1872    return nullptr;1873  }1874  const std::unique_ptr<VPtrInfo> &VFPtr = *VFPtrI;1875 1876  SmallString<256> VFTableName;1877  mangleVFTableName(getMangleContext(), RD, *VFPtr, VFTableName);1878 1879  // Classes marked __declspec(dllimport) need vftables generated on the1880  // import-side in order to support features like constexpr.  No other1881  // translation unit relies on the emission of the local vftable, translation1882  // units are expected to generate them as needed.1883  //1884  // Because of this unique behavior, we maintain this logic here instead of1885  // getVTableLinkage.1886  llvm::GlobalValue::LinkageTypes VFTableLinkage =1887      RD->hasAttr<DLLImportAttr>() ? llvm::GlobalValue::LinkOnceODRLinkage1888                                   : CGM.getVTableLinkage(RD);1889  bool VFTableComesFromAnotherTU =1890      llvm::GlobalValue::isAvailableExternallyLinkage(VFTableLinkage) ||1891      llvm::GlobalValue::isExternalLinkage(VFTableLinkage);1892  bool VTableAliasIsRequred =1893      !VFTableComesFromAnotherTU && getContext().getLangOpts().RTTIData;1894 1895  if (llvm::GlobalValue *VFTable =1896          CGM.getModule().getNamedGlobal(VFTableName)) {1897    VFTablesMap[ID] = VFTable;1898    VTable = VTableAliasIsRequred1899                 ? cast<llvm::GlobalVariable>(1900                       cast<llvm::GlobalAlias>(VFTable)->getAliaseeObject())1901                 : cast<llvm::GlobalVariable>(VFTable);1902    return VTable;1903  }1904 1905  const VTableLayout &VTLayout =1906      VTContext.getVFTableLayout(RD, VFPtr->FullOffsetInMDC);1907  llvm::GlobalValue::LinkageTypes VTableLinkage =1908      VTableAliasIsRequred ? llvm::GlobalValue::PrivateLinkage : VFTableLinkage;1909 1910  StringRef VTableName = VTableAliasIsRequred ? StringRef() : VFTableName.str();1911 1912  llvm::Type *VTableType = CGM.getVTables().getVTableType(VTLayout);1913 1914  // Create a backing variable for the contents of VTable.  The VTable may1915  // or may not include space for a pointer to RTTI data.1916  llvm::GlobalValue *VFTable;1917  VTable = new llvm::GlobalVariable(CGM.getModule(), VTableType,1918                                    /*isConstant=*/true, VTableLinkage,1919                                    /*Initializer=*/nullptr, VTableName);1920  VTable->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);1921 1922  llvm::Comdat *C = nullptr;1923  if (!VFTableComesFromAnotherTU &&1924      llvm::GlobalValue::isWeakForLinker(VFTableLinkage))1925    C = CGM.getModule().getOrInsertComdat(VFTableName.str());1926 1927  // Only insert a pointer into the VFTable for RTTI data if we are not1928  // importing it.  We never reference the RTTI data directly so there is no1929  // need to make room for it.1930  if (VTableAliasIsRequred) {1931    llvm::Value *GEPIndices[] = {llvm::ConstantInt::get(CGM.Int32Ty, 0),1932                                 llvm::ConstantInt::get(CGM.Int32Ty, 0),1933                                 llvm::ConstantInt::get(CGM.Int32Ty, 1)};1934    // Create a GEP which points just after the first entry in the VFTable,1935    // this should be the location of the first virtual method.1936    llvm::Constant *VTableGEP = llvm::ConstantExpr::getInBoundsGetElementPtr(1937        VTable->getValueType(), VTable, GEPIndices);1938    if (llvm::GlobalValue::isWeakForLinker(VFTableLinkage)) {1939      VFTableLinkage = llvm::GlobalValue::ExternalLinkage;1940      if (C)1941        C->setSelectionKind(llvm::Comdat::Largest);1942    }1943    VFTable = llvm::GlobalAlias::create(CGM.Int8PtrTy,1944                                        /*AddressSpace=*/0, VFTableLinkage,1945                                        VFTableName.str(), VTableGEP,1946                                        &CGM.getModule());1947    VFTable->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);1948  } else {1949    // We don't need a GlobalAlias to be a symbol for the VTable if we won't1950    // be referencing any RTTI data.1951    // The GlobalVariable will end up being an appropriate definition of the1952    // VFTable.1953    VFTable = VTable;1954  }1955  if (C)1956    VTable->setComdat(C);1957 1958  if (RD->hasAttr<DLLExportAttr>())1959    VFTable->setDLLStorageClass(llvm::GlobalValue::DLLExportStorageClass);1960 1961  VFTablesMap[ID] = VFTable;1962  return VTable;1963}1964 1965CGCallee MicrosoftCXXABI::getVirtualFunctionPointer(CodeGenFunction &CGF,1966                                                    GlobalDecl GD,1967                                                    Address This,1968                                                    llvm::Type *Ty,1969                                                    SourceLocation Loc) {1970  CGBuilderTy &Builder = CGF.Builder;1971 1972  Ty = CGF.DefaultPtrTy;1973  Address VPtr =1974      adjustThisArgumentForVirtualFunctionCall(CGF, GD, This, true);1975 1976  auto *MethodDecl = cast<CXXMethodDecl>(GD.getDecl());1977  llvm::Value *VTable =1978      CGF.GetVTablePtr(VPtr, CGF.DefaultPtrTy, MethodDecl->getParent());1979 1980  MicrosoftVTableContext &VFTContext = CGM.getMicrosoftVTableContext();1981  MethodVFTableLocation ML = VFTContext.getMethodVFTableLocation(GD);1982 1983  // Compute the identity of the most derived class whose virtual table is1984  // located at the MethodVFTableLocation ML.1985  auto getObjectWithVPtr = [&] {1986    return llvm::find_if(VFTContext.getVFPtrOffsets(1987                             ML.VBase ? ML.VBase : MethodDecl->getParent()),1988                         [&](const std::unique_ptr<VPtrInfo> &Info) {1989                           return Info->FullOffsetInMDC == ML.VFPtrOffset;1990                         })1991        ->get()1992        ->ObjectWithVPtr;1993  };1994 1995  llvm::Value *VFunc;1996  if (CGF.ShouldEmitVTableTypeCheckedLoad(MethodDecl->getParent())) {1997    VFunc = CGF.EmitVTableTypeCheckedLoad(1998        getObjectWithVPtr(), VTable, Ty,1999        ML.Index *2000            CGM.getContext().getTargetInfo().getPointerWidth(LangAS::Default) /2001            8);2002  } else {2003    if (CGM.getCodeGenOpts().PrepareForLTO)2004      CGF.EmitTypeMetadataCodeForVCall(getObjectWithVPtr(), VTable, Loc);2005 2006    llvm::Value *VFuncPtr =2007        Builder.CreateConstInBoundsGEP1_64(Ty, VTable, ML.Index, "vfn");2008    VFunc = Builder.CreateAlignedLoad(Ty, VFuncPtr, CGF.getPointerAlign());2009  }2010 2011  CGCallee Callee(GD, VFunc);2012  return Callee;2013}2014 2015llvm::Value *MicrosoftCXXABI::EmitVirtualDestructorCall(2016    CodeGenFunction &CGF, const CXXDestructorDecl *Dtor, CXXDtorType DtorType,2017    Address This, DeleteOrMemberCallExpr E, llvm::CallBase **CallOrInvoke) {2018  auto *CE = dyn_cast<const CXXMemberCallExpr *>(E);2019  auto *D = dyn_cast<const CXXDeleteExpr *>(E);2020  assert((CE != nullptr) ^ (D != nullptr));2021  assert(CE == nullptr || CE->arguments().empty());2022  assert(DtorType == Dtor_Deleting || DtorType == Dtor_Complete);2023 2024  // We have only one destructor in the vftable but can get both behaviors2025  // by passing an implicit int parameter.2026  GlobalDecl GD(Dtor, Dtor_Deleting);2027  const CGFunctionInfo *FInfo =2028      &CGM.getTypes().arrangeCXXStructorDeclaration(GD);2029  llvm::FunctionType *Ty = CGF.CGM.getTypes().GetFunctionType(*FInfo);2030  CGCallee Callee = CGCallee::forVirtual(CE, GD, This, Ty);2031 2032  ASTContext &Context = getContext();2033  bool IsDeleting = DtorType == Dtor_Deleting;2034  bool IsGlobalDelete = D && D->isGlobalDelete() &&2035                        Context.getTargetInfo().callGlobalDeleteInDeletingDtor(2036                            Context.getLangOpts());2037  llvm::Value *ImplicitParam =2038      CGF.Builder.getInt32((IsDeleting ? 1 : 0) | (IsGlobalDelete ? 4 : 0));2039 2040  QualType ThisTy;2041  if (CE) {2042    ThisTy = CE->getObjectType();2043  } else {2044    ThisTy = D->getDestroyedType();2045  }2046 2047  This = adjustThisArgumentForVirtualFunctionCall(CGF, GD, This, true);2048  RValue RV =2049      CGF.EmitCXXDestructorCall(GD, Callee, This.emitRawPointer(CGF), ThisTy,2050                                ImplicitParam, Context.IntTy, CE, CallOrInvoke);2051  return RV.getScalarVal();2052}2053 2054const VBTableGlobals &2055MicrosoftCXXABI::enumerateVBTables(const CXXRecordDecl *RD) {2056  // At this layer, we can key the cache off of a single class, which is much2057  // easier than caching each vbtable individually.2058  auto [Entry, Added] = VBTablesMap.try_emplace(RD);2059  VBTableGlobals &VBGlobals = Entry->second;2060  if (!Added)2061    return VBGlobals;2062 2063  MicrosoftVTableContext &Context = CGM.getMicrosoftVTableContext();2064  VBGlobals.VBTables = &Context.enumerateVBTables(RD);2065 2066  // Cache the globals for all vbtables so we don't have to recompute the2067  // mangled names.2068  llvm::GlobalVariable::LinkageTypes Linkage = CGM.getVTableLinkage(RD);2069  for (VPtrInfoVector::const_iterator I = VBGlobals.VBTables->begin(),2070                                      E = VBGlobals.VBTables->end();2071       I != E; ++I) {2072    VBGlobals.Globals.push_back(getAddrOfVBTable(**I, RD, Linkage));2073  }2074 2075  return VBGlobals;2076}2077 2078llvm::Function *2079MicrosoftCXXABI::EmitVirtualMemPtrThunk(const CXXMethodDecl *MD,2080                                        const MethodVFTableLocation &ML) {2081  assert(!isa<CXXConstructorDecl>(MD) && !isa<CXXDestructorDecl>(MD) &&2082         "can't form pointers to ctors or virtual dtors");2083 2084  // Calculate the mangled name.2085  SmallString<256> ThunkName;2086  llvm::raw_svector_ostream Out(ThunkName);2087  getMangleContext().mangleVirtualMemPtrThunk(MD, ML, Out);2088 2089  // If the thunk has been generated previously, just return it.2090  if (llvm::GlobalValue *GV = CGM.getModule().getNamedValue(ThunkName))2091    return cast<llvm::Function>(GV);2092 2093  // Create the llvm::Function.2094  const CGFunctionInfo &FnInfo =2095      CGM.getTypes().arrangeUnprototypedMustTailThunk(MD);2096  llvm::FunctionType *ThunkTy = CGM.getTypes().GetFunctionType(FnInfo);2097  llvm::Function *ThunkFn =2098      llvm::Function::Create(ThunkTy, llvm::Function::ExternalLinkage,2099                             ThunkName.str(), &CGM.getModule());2100  assert(ThunkFn->getName() == ThunkName && "name was uniqued!");2101 2102  ThunkFn->setLinkage(MD->isExternallyVisible()2103                          ? llvm::GlobalValue::LinkOnceODRLinkage2104                          : llvm::GlobalValue::InternalLinkage);2105  if (MD->isExternallyVisible())2106    ThunkFn->setComdat(CGM.getModule().getOrInsertComdat(ThunkFn->getName()));2107 2108  CGM.SetLLVMFunctionAttributes(MD, FnInfo, ThunkFn, /*IsThunk=*/false);2109  CGM.SetLLVMFunctionAttributesForDefinition(MD, ThunkFn);2110 2111  // Add the "thunk" attribute so that LLVM knows that the return type is2112  // meaningless. These thunks can be used to call functions with differing2113  // return types, and the caller is required to cast the prototype2114  // appropriately to extract the correct value.2115  ThunkFn->addFnAttr("thunk");2116 2117  // These thunks can be compared, so they are not unnamed.2118  ThunkFn->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::None);2119 2120  // Start codegen.2121  CodeGenFunction CGF(CGM);2122  CGF.CurGD = GlobalDecl(MD);2123  CGF.CurFuncIsThunk = true;2124 2125  // Build FunctionArgs, but only include the implicit 'this' parameter2126  // declaration.2127  FunctionArgList FunctionArgs;2128  buildThisParam(CGF, FunctionArgs);2129 2130  // Start defining the function.2131  CGF.StartFunction(GlobalDecl(), FnInfo.getReturnType(), ThunkFn, FnInfo,2132                    FunctionArgs, MD->getLocation(), SourceLocation());2133 2134  ApplyDebugLocation AL(CGF, MD->getLocation());2135  setCXXABIThisValue(CGF, loadIncomingCXXThis(CGF));2136 2137  // Load the vfptr and then callee from the vftable.  The callee should have2138  // adjusted 'this' so that the vfptr is at offset zero.2139  llvm::Type *ThunkPtrTy = CGF.DefaultPtrTy;2140  llvm::Value *VTable =2141      CGF.GetVTablePtr(getThisAddress(CGF), CGF.DefaultPtrTy, MD->getParent());2142 2143  llvm::Value *VFuncPtr = CGF.Builder.CreateConstInBoundsGEP1_64(2144      ThunkPtrTy, VTable, ML.Index, "vfn");2145  llvm::Value *Callee =2146    CGF.Builder.CreateAlignedLoad(ThunkPtrTy, VFuncPtr, CGF.getPointerAlign());2147 2148  CGF.EmitMustTailThunk(MD, getThisValue(CGF), {ThunkTy, Callee});2149 2150  return ThunkFn;2151}2152 2153void MicrosoftCXXABI::emitVirtualInheritanceTables(const CXXRecordDecl *RD) {2154  const VBTableGlobals &VBGlobals = enumerateVBTables(RD);2155  for (unsigned I = 0, E = VBGlobals.VBTables->size(); I != E; ++I) {2156    const std::unique_ptr<VPtrInfo>& VBT = (*VBGlobals.VBTables)[I];2157    llvm::GlobalVariable *GV = VBGlobals.Globals[I];2158    if (GV->isDeclaration())2159      emitVBTableDefinition(*VBT, RD, GV);2160  }2161}2162 2163llvm::GlobalVariable *2164MicrosoftCXXABI::getAddrOfVBTable(const VPtrInfo &VBT, const CXXRecordDecl *RD,2165                                  llvm::GlobalVariable::LinkageTypes Linkage) {2166  SmallString<256> OutName;2167  llvm::raw_svector_ostream Out(OutName);2168  getMangleContext().mangleCXXVBTable(RD, VBT.MangledPath, Out);2169  StringRef Name = OutName.str();2170 2171  llvm::ArrayType *VBTableType =2172      llvm::ArrayType::get(CGM.IntTy, 1 + VBT.ObjectWithVPtr->getNumVBases());2173 2174  assert(!CGM.getModule().getNamedGlobal(Name) &&2175         "vbtable with this name already exists: mangling bug?");2176  CharUnits Alignment =2177      CGM.getContext().getTypeAlignInChars(CGM.getContext().IntTy);2178  llvm::GlobalVariable *GV = CGM.CreateOrReplaceCXXRuntimeVariable(2179      Name, VBTableType, Linkage, Alignment.getAsAlign());2180  GV->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);2181 2182  if (RD->hasAttr<DLLImportAttr>())2183    GV->setDLLStorageClass(llvm::GlobalValue::DLLImportStorageClass);2184  else if (RD->hasAttr<DLLExportAttr>())2185    GV->setDLLStorageClass(llvm::GlobalValue::DLLExportStorageClass);2186 2187  if (!GV->hasExternalLinkage())2188    emitVBTableDefinition(VBT, RD, GV);2189 2190  return GV;2191}2192 2193void MicrosoftCXXABI::emitVBTableDefinition(const VPtrInfo &VBT,2194                                            const CXXRecordDecl *RD,2195                                            llvm::GlobalVariable *GV) const {2196  const CXXRecordDecl *ObjectWithVPtr = VBT.ObjectWithVPtr;2197 2198  assert(RD->getNumVBases() && ObjectWithVPtr->getNumVBases() &&2199         "should only emit vbtables for classes with vbtables");2200 2201  const ASTRecordLayout &BaseLayout =2202      getContext().getASTRecordLayout(VBT.IntroducingObject);2203  const ASTRecordLayout &DerivedLayout = getContext().getASTRecordLayout(RD);2204 2205  SmallVector<llvm::Constant *, 4> Offsets(1 + ObjectWithVPtr->getNumVBases(),2206                                           nullptr);2207 2208  // The offset from ObjectWithVPtr's vbptr to itself always leads.2209  CharUnits VBPtrOffset = BaseLayout.getVBPtrOffset();2210  Offsets[0] = llvm::ConstantInt::get(CGM.IntTy, -VBPtrOffset.getQuantity());2211 2212  MicrosoftVTableContext &Context = CGM.getMicrosoftVTableContext();2213  for (const auto &I : ObjectWithVPtr->vbases()) {2214    const CXXRecordDecl *VBase = I.getType()->getAsCXXRecordDecl();2215    CharUnits Offset = DerivedLayout.getVBaseClassOffset(VBase);2216    assert(!Offset.isNegative());2217 2218    // Make it relative to the subobject vbptr.2219    CharUnits CompleteVBPtrOffset = VBT.NonVirtualOffset + VBPtrOffset;2220    if (VBT.getVBaseWithVPtr())2221      CompleteVBPtrOffset +=2222          DerivedLayout.getVBaseClassOffset(VBT.getVBaseWithVPtr());2223    Offset -= CompleteVBPtrOffset;2224 2225    unsigned VBIndex = Context.getVBTableIndex(ObjectWithVPtr, VBase);2226    assert(Offsets[VBIndex] == nullptr && "The same vbindex seen twice?");2227    Offsets[VBIndex] = llvm::ConstantInt::get(CGM.IntTy, Offset.getQuantity());2228  }2229 2230  assert(Offsets.size() ==2231         cast<llvm::ArrayType>(GV->getValueType())->getNumElements());2232  llvm::ArrayType *VBTableType =2233    llvm::ArrayType::get(CGM.IntTy, Offsets.size());2234  llvm::Constant *Init = llvm::ConstantArray::get(VBTableType, Offsets);2235  GV->setInitializer(Init);2236 2237  if (RD->hasAttr<DLLImportAttr>())2238    GV->setLinkage(llvm::GlobalVariable::AvailableExternallyLinkage);2239}2240 2241llvm::Value *MicrosoftCXXABI::performThisAdjustment(2242    CodeGenFunction &CGF, Address This,2243    const CXXRecordDecl * /*UnadjustedClass*/, const ThunkInfo &TI) {2244  const ThisAdjustment &TA = TI.This;2245  if (TA.isEmpty())2246    return This.emitRawPointer(CGF);2247 2248  This = This.withElementType(CGF.Int8Ty);2249 2250  llvm::Value *V;2251  if (TA.Virtual.isEmpty()) {2252    V = This.emitRawPointer(CGF);2253  } else {2254    assert(TA.Virtual.Microsoft.VtordispOffset < 0);2255    // Adjust the this argument based on the vtordisp value.2256    Address VtorDispPtr =2257        CGF.Builder.CreateConstInBoundsByteGEP(This,2258                 CharUnits::fromQuantity(TA.Virtual.Microsoft.VtordispOffset));2259    VtorDispPtr = VtorDispPtr.withElementType(CGF.Int32Ty);2260    llvm::Value *VtorDisp = CGF.Builder.CreateLoad(VtorDispPtr, "vtordisp");2261    V = CGF.Builder.CreateGEP(This.getElementType(), This.emitRawPointer(CGF),2262                              CGF.Builder.CreateNeg(VtorDisp));2263 2264    // Unfortunately, having applied the vtordisp means that we no2265    // longer really have a known alignment for the vbptr step.2266    // We'll assume the vbptr is pointer-aligned.2267 2268    if (TA.Virtual.Microsoft.VBPtrOffset) {2269      // If the final overrider is defined in a virtual base other than the one2270      // that holds the vfptr, we have to use a vtordispex thunk which looks up2271      // the vbtable of the derived class.2272      assert(TA.Virtual.Microsoft.VBPtrOffset > 0);2273      assert(TA.Virtual.Microsoft.VBOffsetOffset >= 0);2274      llvm::Value *VBPtr;2275      llvm::Value *VBaseOffset = GetVBaseOffsetFromVBPtr(2276          CGF, Address(V, CGF.Int8Ty, CGF.getPointerAlign()),2277          -TA.Virtual.Microsoft.VBPtrOffset,2278          TA.Virtual.Microsoft.VBOffsetOffset, &VBPtr);2279      V = CGF.Builder.CreateInBoundsGEP(CGF.Int8Ty, VBPtr, VBaseOffset);2280    }2281  }2282 2283  if (TA.NonVirtual) {2284    // Non-virtual adjustment might result in a pointer outside the allocated2285    // object, e.g. if the final overrider class is laid out after the virtual2286    // base that declares a method in the most derived class.2287    V = CGF.Builder.CreateConstGEP1_32(CGF.Int8Ty, V, TA.NonVirtual);2288  }2289 2290  // Don't need to bitcast back, the call CodeGen will handle this.2291  return V;2292}2293 2294llvm::Value *MicrosoftCXXABI::performReturnAdjustment(2295    CodeGenFunction &CGF, Address Ret,2296    const CXXRecordDecl * /*UnadjustedClass*/, const ReturnAdjustment &RA) {2297 2298  if (RA.isEmpty())2299    return Ret.emitRawPointer(CGF);2300 2301  Ret = Ret.withElementType(CGF.Int8Ty);2302 2303  llvm::Value *V = Ret.emitRawPointer(CGF);2304  if (RA.Virtual.Microsoft.VBIndex) {2305    assert(RA.Virtual.Microsoft.VBIndex > 0);2306    int32_t IntSize = CGF.getIntSize().getQuantity();2307    llvm::Value *VBPtr;2308    llvm::Value *VBaseOffset =2309        GetVBaseOffsetFromVBPtr(CGF, Ret, RA.Virtual.Microsoft.VBPtrOffset,2310                                IntSize * RA.Virtual.Microsoft.VBIndex, &VBPtr);2311    V = CGF.Builder.CreateInBoundsGEP(CGF.Int8Ty, VBPtr, VBaseOffset);2312  }2313 2314  if (RA.NonVirtual)2315    V = CGF.Builder.CreateConstInBoundsGEP1_32(CGF.Int8Ty, V, RA.NonVirtual);2316 2317  return V;2318}2319 2320bool MicrosoftCXXABI::requiresArrayCookie(const CXXDeleteExpr *expr,2321                                   QualType elementType) {2322  // Microsoft seems to completely ignore the possibility of a2323  // two-argument usual deallocation function.2324  return elementType.isDestructedType();2325}2326 2327bool MicrosoftCXXABI::requiresArrayCookie(const CXXNewExpr *expr) {2328  // Microsoft seems to completely ignore the possibility of a2329  // two-argument usual deallocation function.2330  return expr->getAllocatedType().isDestructedType();2331}2332 2333CharUnits MicrosoftCXXABI::getArrayCookieSizeImpl(QualType type) {2334  // The array cookie is always a size_t; we then pad that out to the2335  // alignment of the element type.2336  ASTContext &Ctx = getContext();2337  return std::max(Ctx.getTypeSizeInChars(Ctx.getSizeType()),2338                  Ctx.getTypeAlignInChars(type));2339}2340 2341llvm::Value *MicrosoftCXXABI::readArrayCookieImpl(CodeGenFunction &CGF,2342                                                  Address allocPtr,2343                                                  CharUnits cookieSize) {2344  Address numElementsPtr = allocPtr.withElementType(CGF.SizeTy);2345  return CGF.Builder.CreateLoad(numElementsPtr);2346}2347 2348Address MicrosoftCXXABI::InitializeArrayCookie(CodeGenFunction &CGF,2349                                               Address newPtr,2350                                               llvm::Value *numElements,2351                                               const CXXNewExpr *expr,2352                                               QualType elementType) {2353  assert(requiresArrayCookie(expr));2354 2355  // The size of the cookie.2356  CharUnits cookieSize = getArrayCookieSizeImpl(elementType);2357 2358  // Compute an offset to the cookie.2359  Address cookiePtr = newPtr;2360 2361  // Write the number of elements into the appropriate slot.2362  Address numElementsPtr = cookiePtr.withElementType(CGF.SizeTy);2363  CGF.Builder.CreateStore(numElements, numElementsPtr);2364 2365  // Finally, compute a pointer to the actual data buffer by skipping2366  // over the cookie completely.2367  return CGF.Builder.CreateConstInBoundsByteGEP(newPtr, cookieSize);2368}2369 2370static void emitGlobalDtorWithTLRegDtor(CodeGenFunction &CGF, const VarDecl &VD,2371                                        llvm::FunctionCallee Dtor,2372                                        llvm::Constant *Addr) {2373  // Create a function which calls the destructor.2374  llvm::Constant *DtorStub = CGF.createAtExitStub(VD, Dtor, Addr);2375 2376  // extern "C" int __tlregdtor(void (*f)(void));2377  llvm::FunctionType *TLRegDtorTy = llvm::FunctionType::get(2378      CGF.IntTy, DtorStub->getType(), /*isVarArg=*/false);2379 2380  llvm::FunctionCallee TLRegDtor = CGF.CGM.CreateRuntimeFunction(2381      TLRegDtorTy, "__tlregdtor", llvm::AttributeList(), /*Local=*/true);2382  if (llvm::Function *TLRegDtorFn =2383          dyn_cast<llvm::Function>(TLRegDtor.getCallee()))2384    TLRegDtorFn->setDoesNotThrow();2385 2386  CGF.EmitNounwindRuntimeCall(TLRegDtor, DtorStub);2387}2388 2389void MicrosoftCXXABI::registerGlobalDtor(CodeGenFunction &CGF, const VarDecl &D,2390                                         llvm::FunctionCallee Dtor,2391                                         llvm::Constant *Addr) {2392  if (D.isNoDestroy(CGM.getContext()))2393    return;2394 2395  if (D.getTLSKind())2396    return emitGlobalDtorWithTLRegDtor(CGF, D, Dtor, Addr);2397 2398  // HLSL doesn't support atexit.2399  if (CGM.getLangOpts().HLSL)2400    return CGM.AddCXXDtorEntry(Dtor, Addr);2401 2402  // The default behavior is to use atexit.2403  CGF.registerGlobalDtorWithAtExit(D, Dtor, Addr);2404}2405 2406void MicrosoftCXXABI::EmitThreadLocalInitFuncs(2407    CodeGenModule &CGM, ArrayRef<const VarDecl *> CXXThreadLocals,2408    ArrayRef<llvm::Function *> CXXThreadLocalInits,2409    ArrayRef<const VarDecl *> CXXThreadLocalInitVars) {2410  if (CXXThreadLocalInits.empty())2411    return;2412 2413  CGM.AppendLinkerOptions(CGM.getTarget().getTriple().getArch() ==2414                                  llvm::Triple::x862415                              ? "/include:___dyn_tls_init@12"2416                              : "/include:__dyn_tls_init");2417 2418  // This will create a GV in the .CRT$XDU section.  It will point to our2419  // initialization function.  The CRT will call all of these function2420  // pointers at start-up time and, eventually, at thread-creation time.2421  auto AddToXDU = [&CGM](llvm::Function *InitFunc) {2422    llvm::GlobalVariable *InitFuncPtr = new llvm::GlobalVariable(2423        CGM.getModule(), InitFunc->getType(), /*isConstant=*/true,2424        llvm::GlobalVariable::InternalLinkage, InitFunc,2425        Twine(InitFunc->getName(), "$initializer$"));2426    InitFuncPtr->setSection(".CRT$XDU");2427    // This variable has discardable linkage, we have to add it to @llvm.used to2428    // ensure it won't get discarded.2429    CGM.addUsedGlobal(InitFuncPtr);2430    return InitFuncPtr;2431  };2432 2433  std::vector<llvm::Function *> NonComdatInits;2434  for (size_t I = 0, E = CXXThreadLocalInitVars.size(); I != E; ++I) {2435    llvm::GlobalVariable *GV = cast<llvm::GlobalVariable>(2436        CGM.GetGlobalValue(CGM.getMangledName(CXXThreadLocalInitVars[I])));2437    llvm::Function *F = CXXThreadLocalInits[I];2438 2439    // If the GV is already in a comdat group, then we have to join it.2440    if (llvm::Comdat *C = GV->getComdat())2441      AddToXDU(F)->setComdat(C);2442    else2443      NonComdatInits.push_back(F);2444  }2445 2446  if (!NonComdatInits.empty()) {2447    llvm::FunctionType *FTy =2448        llvm::FunctionType::get(CGM.VoidTy, /*isVarArg=*/false);2449    llvm::Function *InitFunc = CGM.CreateGlobalInitOrCleanUpFunction(2450        FTy, "__tls_init", CGM.getTypes().arrangeNullaryFunction(),2451        SourceLocation(), /*TLS=*/true);2452    CodeGenFunction(CGM).GenerateCXXGlobalInitFunc(InitFunc, NonComdatInits);2453 2454    AddToXDU(InitFunc);2455  }2456}2457 2458static llvm::GlobalValue *getTlsGuardVar(CodeGenModule &CGM) {2459  // __tls_guard comes from the MSVC runtime and reflects2460  // whether TLS has been initialized for a particular thread.2461  // It is set from within __dyn_tls_init by the runtime.2462  // Every library and executable has its own variable.2463  llvm::Type *VTy = llvm::Type::getInt8Ty(CGM.getLLVMContext());2464  llvm::Constant *TlsGuardConstant =2465      CGM.CreateRuntimeVariable(VTy, "__tls_guard");2466  llvm::GlobalValue *TlsGuard = cast<llvm::GlobalValue>(TlsGuardConstant);2467 2468  TlsGuard->setThreadLocal(true);2469 2470  return TlsGuard;2471}2472 2473static llvm::FunctionCallee getDynTlsOnDemandInitFn(CodeGenModule &CGM) {2474  // __dyn_tls_on_demand_init comes from the MSVC runtime and triggers2475  // dynamic TLS initialization by calling __dyn_tls_init internally.2476  llvm::FunctionType *FTy =2477      llvm::FunctionType::get(llvm::Type::getVoidTy(CGM.getLLVMContext()), {},2478                              /*isVarArg=*/false);2479  return CGM.CreateRuntimeFunction(2480      FTy, "__dyn_tls_on_demand_init",2481      llvm::AttributeList::get(CGM.getLLVMContext(),2482                               llvm::AttributeList::FunctionIndex,2483                               llvm::Attribute::NoUnwind),2484      /*Local=*/true);2485}2486 2487static void emitTlsGuardCheck(CodeGenFunction &CGF, llvm::GlobalValue *TlsGuard,2488                              llvm::BasicBlock *DynInitBB,2489                              llvm::BasicBlock *ContinueBB) {2490  llvm::LoadInst *TlsGuardValue =2491      CGF.Builder.CreateLoad(Address(TlsGuard, CGF.Int8Ty, CharUnits::One()));2492  llvm::Value *CmpResult =2493      CGF.Builder.CreateICmpEQ(TlsGuardValue, CGF.Builder.getInt8(0));2494  CGF.Builder.CreateCondBr(CmpResult, DynInitBB, ContinueBB);2495}2496 2497static void emitDynamicTlsInitializationCall(CodeGenFunction &CGF,2498                                             llvm::GlobalValue *TlsGuard,2499                                             llvm::BasicBlock *ContinueBB) {2500  llvm::FunctionCallee Initializer = getDynTlsOnDemandInitFn(CGF.CGM);2501  llvm::Function *InitializerFunction =2502      cast<llvm::Function>(Initializer.getCallee());2503  llvm::CallInst *CallVal = CGF.Builder.CreateCall(InitializerFunction);2504  CallVal->setCallingConv(InitializerFunction->getCallingConv());2505 2506  CGF.Builder.CreateBr(ContinueBB);2507}2508 2509static void emitDynamicTlsInitialization(CodeGenFunction &CGF) {2510  llvm::BasicBlock *DynInitBB =2511      CGF.createBasicBlock("dyntls.dyn_init", CGF.CurFn);2512  llvm::BasicBlock *ContinueBB =2513      CGF.createBasicBlock("dyntls.continue", CGF.CurFn);2514 2515  llvm::GlobalValue *TlsGuard = getTlsGuardVar(CGF.CGM);2516 2517  emitTlsGuardCheck(CGF, TlsGuard, DynInitBB, ContinueBB);2518  CGF.Builder.SetInsertPoint(DynInitBB);2519  emitDynamicTlsInitializationCall(CGF, TlsGuard, ContinueBB);2520  CGF.Builder.SetInsertPoint(ContinueBB);2521}2522 2523LValue MicrosoftCXXABI::EmitThreadLocalVarDeclLValue(CodeGenFunction &CGF,2524                                                     const VarDecl *VD,2525                                                     QualType LValType) {2526  // Dynamic TLS initialization works by checking the state of a2527  // guard variable (__tls_guard) to see whether TLS initialization2528  // for a thread has happend yet.2529  // If not, the initialization is triggered on-demand2530  // by calling __dyn_tls_on_demand_init.2531  emitDynamicTlsInitialization(CGF);2532 2533  // Emit the variable just like any regular global variable.2534 2535  llvm::Value *V = CGF.CGM.GetAddrOfGlobalVar(VD);2536  llvm::Type *RealVarTy = CGF.getTypes().ConvertTypeForMem(VD->getType());2537 2538  CharUnits Alignment = CGF.getContext().getDeclAlign(VD);2539  Address Addr(V, RealVarTy, Alignment);2540 2541  LValue LV = VD->getType()->isReferenceType()2542                  ? CGF.EmitLoadOfReferenceLValue(Addr, VD->getType(),2543                                                  AlignmentSource::Decl)2544                  : CGF.MakeAddrLValue(Addr, LValType, AlignmentSource::Decl);2545  return LV;2546}2547 2548static ConstantAddress getInitThreadEpochPtr(CodeGenModule &CGM) {2549  StringRef VarName("_Init_thread_epoch");2550  CharUnits Align = CGM.getIntAlign();2551  if (auto *GV = CGM.getModule().getNamedGlobal(VarName))2552    return ConstantAddress(GV, GV->getValueType(), Align);2553  auto *GV = new llvm::GlobalVariable(2554      CGM.getModule(), CGM.IntTy,2555      /*isConstant=*/false, llvm::GlobalVariable::ExternalLinkage,2556      /*Initializer=*/nullptr, VarName,2557      /*InsertBefore=*/nullptr, llvm::GlobalVariable::GeneralDynamicTLSModel);2558  GV->setAlignment(Align.getAsAlign());2559  return ConstantAddress(GV, GV->getValueType(), Align);2560}2561 2562static llvm::FunctionCallee getInitThreadHeaderFn(CodeGenModule &CGM) {2563  llvm::FunctionType *FTy =2564      llvm::FunctionType::get(llvm::Type::getVoidTy(CGM.getLLVMContext()),2565                              CGM.DefaultPtrTy, /*isVarArg=*/false);2566  return CGM.CreateRuntimeFunction(2567      FTy, "_Init_thread_header",2568      llvm::AttributeList::get(CGM.getLLVMContext(),2569                               llvm::AttributeList::FunctionIndex,2570                               llvm::Attribute::NoUnwind),2571      /*Local=*/true);2572}2573 2574static llvm::FunctionCallee getInitThreadFooterFn(CodeGenModule &CGM) {2575  llvm::FunctionType *FTy =2576      llvm::FunctionType::get(llvm::Type::getVoidTy(CGM.getLLVMContext()),2577                              CGM.DefaultPtrTy, /*isVarArg=*/false);2578  return CGM.CreateRuntimeFunction(2579      FTy, "_Init_thread_footer",2580      llvm::AttributeList::get(CGM.getLLVMContext(),2581                               llvm::AttributeList::FunctionIndex,2582                               llvm::Attribute::NoUnwind),2583      /*Local=*/true);2584}2585 2586static llvm::FunctionCallee getInitThreadAbortFn(CodeGenModule &CGM) {2587  llvm::FunctionType *FTy =2588      llvm::FunctionType::get(llvm::Type::getVoidTy(CGM.getLLVMContext()),2589                              CGM.DefaultPtrTy, /*isVarArg=*/false);2590  return CGM.CreateRuntimeFunction(2591      FTy, "_Init_thread_abort",2592      llvm::AttributeList::get(CGM.getLLVMContext(),2593                               llvm::AttributeList::FunctionIndex,2594                               llvm::Attribute::NoUnwind),2595      /*Local=*/true);2596}2597 2598namespace {2599struct ResetGuardBit final : EHScopeStack::Cleanup {2600  Address Guard;2601  unsigned GuardNum;2602  ResetGuardBit(Address Guard, unsigned GuardNum)2603      : Guard(Guard), GuardNum(GuardNum) {}2604 2605  void Emit(CodeGenFunction &CGF, Flags flags) override {2606    // Reset the bit in the mask so that the static variable may be2607    // reinitialized.2608    CGBuilderTy &Builder = CGF.Builder;2609    llvm::LoadInst *LI = Builder.CreateLoad(Guard);2610    llvm::ConstantInt *Mask =2611        llvm::ConstantInt::get(CGF.IntTy, ~(1ULL << GuardNum));2612    Builder.CreateStore(Builder.CreateAnd(LI, Mask), Guard);2613  }2614};2615 2616struct CallInitThreadAbort final : EHScopeStack::Cleanup {2617  llvm::Value *Guard;2618  CallInitThreadAbort(RawAddress Guard) : Guard(Guard.getPointer()) {}2619 2620  void Emit(CodeGenFunction &CGF, Flags flags) override {2621    // Calling _Init_thread_abort will reset the guard's state.2622    CGF.EmitNounwindRuntimeCall(getInitThreadAbortFn(CGF.CGM), Guard);2623  }2624};2625}2626 2627void MicrosoftCXXABI::EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D,2628                                      llvm::GlobalVariable *GV,2629                                      bool PerformInit) {2630  // MSVC only uses guards for static locals.2631  if (!D.isStaticLocal()) {2632    assert(GV->hasWeakLinkage() || GV->hasLinkOnceLinkage());2633    // GlobalOpt is allowed to discard the initializer, so use linkonce_odr.2634    llvm::Function *F = CGF.CurFn;2635    F->setLinkage(llvm::GlobalValue::LinkOnceODRLinkage);2636    F->setComdat(CGM.getModule().getOrInsertComdat(F->getName()));2637    CGF.EmitCXXGlobalVarDeclInit(D, GV, PerformInit);2638    return;2639  }2640 2641  bool ThreadlocalStatic = D.getTLSKind();2642  bool ThreadsafeStatic = getContext().getLangOpts().ThreadsafeStatics;2643 2644  // Thread-safe static variables which aren't thread-specific have a2645  // per-variable guard.2646  bool HasPerVariableGuard = ThreadsafeStatic && !ThreadlocalStatic;2647 2648  CGBuilderTy &Builder = CGF.Builder;2649  llvm::IntegerType *GuardTy = CGF.Int32Ty;2650  llvm::ConstantInt *Zero = llvm::ConstantInt::get(GuardTy, 0);2651  CharUnits GuardAlign = CharUnits::fromQuantity(4);2652 2653  // Get the guard variable for this function if we have one already.2654  GuardInfo *GI = nullptr;2655  if (ThreadlocalStatic)2656    GI = &ThreadLocalGuardVariableMap[D.getDeclContext()];2657  else if (!ThreadsafeStatic)2658    GI = &GuardVariableMap[D.getDeclContext()];2659 2660  llvm::GlobalVariable *GuardVar = GI ? GI->Guard : nullptr;2661  unsigned GuardNum;2662  if (D.isExternallyVisible()) {2663    // Externally visible variables have to be numbered in Sema to properly2664    // handle unreachable VarDecls.2665    GuardNum = getContext().getStaticLocalNumber(&D);2666    assert(GuardNum > 0);2667    GuardNum--;2668  } else if (HasPerVariableGuard) {2669    GuardNum = ThreadSafeGuardNumMap[D.getDeclContext()]++;2670  } else {2671    // Non-externally visible variables are numbered here in CodeGen.2672    GuardNum = GI->BitIndex++;2673  }2674 2675  if (!HasPerVariableGuard && GuardNum >= 32) {2676    if (D.isExternallyVisible())2677      ErrorUnsupportedABI(CGF, "more than 32 guarded initializations");2678    GuardNum %= 32;2679    GuardVar = nullptr;2680  }2681 2682  if (!GuardVar) {2683    // Mangle the name for the guard.2684    SmallString<256> GuardName;2685    {2686      llvm::raw_svector_ostream Out(GuardName);2687      if (HasPerVariableGuard)2688        getMangleContext().mangleThreadSafeStaticGuardVariable(&D, GuardNum,2689                                                               Out);2690      else2691        getMangleContext().mangleStaticGuardVariable(&D, Out);2692    }2693 2694    // Create the guard variable with a zero-initializer. Just absorb linkage,2695    // visibility and dll storage class from the guarded variable.2696    GuardVar =2697        new llvm::GlobalVariable(CGM.getModule(), GuardTy, /*isConstant=*/false,2698                                 GV->getLinkage(), Zero, GuardName.str());2699    GuardVar->setVisibility(GV->getVisibility());2700    GuardVar->setDLLStorageClass(GV->getDLLStorageClass());2701    GuardVar->setAlignment(GuardAlign.getAsAlign());2702    if (GuardVar->isWeakForLinker())2703      GuardVar->setComdat(2704          CGM.getModule().getOrInsertComdat(GuardVar->getName()));2705    if (D.getTLSKind())2706      CGM.setTLSMode(GuardVar, D);2707    if (GI && !HasPerVariableGuard)2708      GI->Guard = GuardVar;2709  }2710 2711  ConstantAddress GuardAddr(GuardVar, GuardTy, GuardAlign);2712 2713  assert(GuardVar->getLinkage() == GV->getLinkage() &&2714         "static local from the same function had different linkage");2715 2716  if (!HasPerVariableGuard) {2717    // Pseudo code for the test:2718    // if (!(GuardVar & MyGuardBit)) {2719    //   GuardVar |= MyGuardBit;2720    //   ... initialize the object ...;2721    // }2722 2723    // Test our bit from the guard variable.2724    llvm::ConstantInt *Bit = llvm::ConstantInt::get(GuardTy, 1ULL << GuardNum);2725    llvm::LoadInst *LI = Builder.CreateLoad(GuardAddr);2726    llvm::Value *NeedsInit =2727        Builder.CreateICmpEQ(Builder.CreateAnd(LI, Bit), Zero);2728    llvm::BasicBlock *InitBlock = CGF.createBasicBlock("init");2729    llvm::BasicBlock *EndBlock = CGF.createBasicBlock("init.end");2730    CGF.EmitCXXGuardedInitBranch(NeedsInit, InitBlock, EndBlock,2731                                 CodeGenFunction::GuardKind::VariableGuard, &D);2732 2733    // Set our bit in the guard variable and emit the initializer and add a global2734    // destructor if appropriate.2735    CGF.EmitBlock(InitBlock);2736    Builder.CreateStore(Builder.CreateOr(LI, Bit), GuardAddr);2737    CGF.EHStack.pushCleanup<ResetGuardBit>(EHCleanup, GuardAddr, GuardNum);2738    CGF.EmitCXXGlobalVarDeclInit(D, GV, PerformInit);2739    CGF.PopCleanupBlock();2740    Builder.CreateBr(EndBlock);2741 2742    // Continue.2743    CGF.EmitBlock(EndBlock);2744  } else {2745    // Pseudo code for the test:2746    // if (TSS > _Init_thread_epoch) {2747    //   _Init_thread_header(&TSS);2748    //   if (TSS == -1) {2749    //     ... initialize the object ...;2750    //     _Init_thread_footer(&TSS);2751    //   }2752    // }2753    //2754    // The algorithm is almost identical to what can be found in the appendix2755    // found in N2325.2756 2757    // This BasicBLock determines whether or not we have any work to do.2758    llvm::LoadInst *FirstGuardLoad = Builder.CreateLoad(GuardAddr);2759    FirstGuardLoad->setOrdering(llvm::AtomicOrdering::Unordered);2760    llvm::LoadInst *InitThreadEpoch =2761        Builder.CreateLoad(getInitThreadEpochPtr(CGM));2762    llvm::Value *IsUninitialized =2763        Builder.CreateICmpSGT(FirstGuardLoad, InitThreadEpoch);2764    llvm::BasicBlock *AttemptInitBlock = CGF.createBasicBlock("init.attempt");2765    llvm::BasicBlock *EndBlock = CGF.createBasicBlock("init.end");2766    CGF.EmitCXXGuardedInitBranch(IsUninitialized, AttemptInitBlock, EndBlock,2767                                 CodeGenFunction::GuardKind::VariableGuard, &D);2768 2769    // This BasicBlock attempts to determine whether or not this thread is2770    // responsible for doing the initialization.2771    CGF.EmitBlock(AttemptInitBlock);2772    CGF.EmitNounwindRuntimeCall(getInitThreadHeaderFn(CGM),2773                                GuardAddr.getPointer());2774    llvm::LoadInst *SecondGuardLoad = Builder.CreateLoad(GuardAddr);2775    SecondGuardLoad->setOrdering(llvm::AtomicOrdering::Unordered);2776    llvm::Value *ShouldDoInit =2777        Builder.CreateICmpEQ(SecondGuardLoad, getAllOnesInt());2778    llvm::BasicBlock *InitBlock = CGF.createBasicBlock("init");2779    Builder.CreateCondBr(ShouldDoInit, InitBlock, EndBlock);2780 2781    // Ok, we ended up getting selected as the initializing thread.2782    CGF.EmitBlock(InitBlock);2783    CGF.EHStack.pushCleanup<CallInitThreadAbort>(EHCleanup, GuardAddr);2784    CGF.EmitCXXGlobalVarDeclInit(D, GV, PerformInit);2785    CGF.PopCleanupBlock();2786    CGF.EmitNounwindRuntimeCall(getInitThreadFooterFn(CGM),2787                                GuardAddr.getPointer());2788    Builder.CreateBr(EndBlock);2789 2790    CGF.EmitBlock(EndBlock);2791  }2792}2793 2794bool MicrosoftCXXABI::isZeroInitializable(const MemberPointerType *MPT) {2795  // Null-ness for function memptrs only depends on the first field, which is2796  // the function pointer.  The rest don't matter, so we can zero initialize.2797  if (MPT->isMemberFunctionPointer())2798    return true;2799 2800  // The virtual base adjustment field is always -1 for null, so if we have one2801  // we can't zero initialize.  The field offset is sometimes also -1 if 0 is a2802  // valid field offset.2803  const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();2804  MSInheritanceModel Inheritance = RD->getMSInheritanceModel();2805  return (!inheritanceModelHasVBTableOffsetField(Inheritance) &&2806          RD->nullFieldOffsetIsZero());2807}2808 2809llvm::Type *2810MicrosoftCXXABI::ConvertMemberPointerType(const MemberPointerType *MPT) {2811  const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();2812  MSInheritanceModel Inheritance = RD->getMSInheritanceModel();2813  llvm::SmallVector<llvm::Type *, 4> fields;2814  if (MPT->isMemberFunctionPointer())2815    fields.push_back(CGM.VoidPtrTy);  // FunctionPointerOrVirtualThunk2816  else2817    fields.push_back(CGM.IntTy);  // FieldOffset2818 2819  if (inheritanceModelHasNVOffsetField(MPT->isMemberFunctionPointer(),2820                                       Inheritance))2821    fields.push_back(CGM.IntTy);2822  if (inheritanceModelHasVBPtrOffsetField(Inheritance))2823    fields.push_back(CGM.IntTy);2824  if (inheritanceModelHasVBTableOffsetField(Inheritance))2825    fields.push_back(CGM.IntTy);  // VirtualBaseAdjustmentOffset2826 2827  if (fields.size() == 1)2828    return fields[0];2829  return llvm::StructType::get(CGM.getLLVMContext(), fields);2830}2831 2832void MicrosoftCXXABI::2833GetNullMemberPointerFields(const MemberPointerType *MPT,2834                           llvm::SmallVectorImpl<llvm::Constant *> &fields) {2835  assert(fields.empty());2836  const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();2837  MSInheritanceModel Inheritance = RD->getMSInheritanceModel();2838  if (MPT->isMemberFunctionPointer()) {2839    // FunctionPointerOrVirtualThunk2840    fields.push_back(llvm::Constant::getNullValue(CGM.VoidPtrTy));2841  } else {2842    if (RD->nullFieldOffsetIsZero())2843      fields.push_back(getZeroInt());  // FieldOffset2844    else2845      fields.push_back(getAllOnesInt());  // FieldOffset2846  }2847 2848  if (inheritanceModelHasNVOffsetField(MPT->isMemberFunctionPointer(),2849                                       Inheritance))2850    fields.push_back(getZeroInt());2851  if (inheritanceModelHasVBPtrOffsetField(Inheritance))2852    fields.push_back(getZeroInt());2853  if (inheritanceModelHasVBTableOffsetField(Inheritance))2854    fields.push_back(getAllOnesInt());2855}2856 2857llvm::Constant *2858MicrosoftCXXABI::EmitNullMemberPointer(const MemberPointerType *MPT) {2859  llvm::SmallVector<llvm::Constant *, 4> fields;2860  GetNullMemberPointerFields(MPT, fields);2861  if (fields.size() == 1)2862    return fields[0];2863  llvm::Constant *Res = llvm::ConstantStruct::getAnon(fields);2864  assert(Res->getType() == ConvertMemberPointerType(MPT));2865  return Res;2866}2867 2868llvm::Constant *2869MicrosoftCXXABI::EmitFullMemberPointer(llvm::Constant *FirstField,2870                                       bool IsMemberFunction,2871                                       const CXXRecordDecl *RD,2872                                       CharUnits NonVirtualBaseAdjustment,2873                                       unsigned VBTableIndex) {2874  MSInheritanceModel Inheritance = RD->getMSInheritanceModel();2875 2876  // Single inheritance class member pointer are represented as scalars instead2877  // of aggregates.2878  if (inheritanceModelHasOnlyOneField(IsMemberFunction, Inheritance))2879    return FirstField;2880 2881  llvm::SmallVector<llvm::Constant *, 4> fields;2882  fields.push_back(FirstField);2883 2884  if (inheritanceModelHasNVOffsetField(IsMemberFunction, Inheritance))2885    fields.push_back(llvm::ConstantInt::get(2886      CGM.IntTy, NonVirtualBaseAdjustment.getQuantity()));2887 2888  if (inheritanceModelHasVBPtrOffsetField(Inheritance)) {2889    CharUnits Offs = CharUnits::Zero();2890    if (VBTableIndex)2891      Offs = getContext().getASTRecordLayout(RD).getVBPtrOffset();2892    fields.push_back(llvm::ConstantInt::get(CGM.IntTy, Offs.getQuantity()));2893  }2894 2895  // The rest of the fields are adjusted by conversions to a more derived class.2896  if (inheritanceModelHasVBTableOffsetField(Inheritance))2897    fields.push_back(llvm::ConstantInt::get(CGM.IntTy, VBTableIndex));2898 2899  return llvm::ConstantStruct::getAnon(fields);2900}2901 2902llvm::Constant *2903MicrosoftCXXABI::EmitMemberDataPointer(const MemberPointerType *MPT,2904                                       CharUnits offset) {2905  return EmitMemberDataPointer(MPT->getMostRecentCXXRecordDecl(), offset);2906}2907 2908llvm::Constant *MicrosoftCXXABI::EmitMemberDataPointer(const CXXRecordDecl *RD,2909                                                       CharUnits offset) {2910  if (RD->getMSInheritanceModel() ==2911      MSInheritanceModel::Virtual)2912    offset -= getContext().getOffsetOfBaseWithVBPtr(RD);2913  llvm::Constant *FirstField =2914    llvm::ConstantInt::get(CGM.IntTy, offset.getQuantity());2915  return EmitFullMemberPointer(FirstField, /*IsMemberFunction=*/false, RD,2916                               CharUnits::Zero(), /*VBTableIndex=*/0);2917}2918 2919llvm::Constant *MicrosoftCXXABI::EmitMemberPointer(const APValue &MP,2920                                                   QualType MPType) {2921  const MemberPointerType *DstTy = MPType->castAs<MemberPointerType>();2922  const ValueDecl *MPD = MP.getMemberPointerDecl();2923  if (!MPD)2924    return EmitNullMemberPointer(DstTy);2925 2926  ASTContext &Ctx = getContext();2927  ArrayRef<const CXXRecordDecl *> MemberPointerPath = MP.getMemberPointerPath();2928 2929  llvm::Constant *C;2930  if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(MPD)) {2931    C = EmitMemberFunctionPointer(MD);2932  } else {2933    // For a pointer to data member, start off with the offset of the field in2934    // the class in which it was declared, and convert from there if necessary.2935    // For indirect field decls, get the outermost anonymous field and use the2936    // parent class.2937    CharUnits FieldOffset = Ctx.toCharUnitsFromBits(Ctx.getFieldOffset(MPD));2938    const FieldDecl *FD = dyn_cast<FieldDecl>(MPD);2939    if (!FD)2940      FD = cast<FieldDecl>(*cast<IndirectFieldDecl>(MPD)->chain_begin());2941    const CXXRecordDecl *RD = cast<CXXRecordDecl>(FD->getParent());2942    RD = RD->getMostRecentDecl();2943    C = EmitMemberDataPointer(RD, FieldOffset);2944  }2945 2946  if (!MemberPointerPath.empty()) {2947    const CXXRecordDecl *SrcRD = cast<CXXRecordDecl>(MPD->getDeclContext());2948    const MemberPointerType *SrcTy =2949        Ctx.getMemberPointerType(DstTy->getPointeeType(),2950                                 /*Qualifier=*/std::nullopt, SrcRD)2951            ->castAs<MemberPointerType>();2952 2953    bool DerivedMember = MP.isMemberPointerToDerivedMember();2954    SmallVector<const CXXBaseSpecifier *, 4> DerivedToBasePath;2955    const CXXRecordDecl *PrevRD = SrcRD;2956    for (const CXXRecordDecl *PathElem : MemberPointerPath) {2957      const CXXRecordDecl *Base = nullptr;2958      const CXXRecordDecl *Derived = nullptr;2959      if (DerivedMember) {2960        Base = PathElem;2961        Derived = PrevRD;2962      } else {2963        Base = PrevRD;2964        Derived = PathElem;2965      }2966      for (const CXXBaseSpecifier &BS : Derived->bases())2967        if (BS.getType()->getAsCXXRecordDecl()->getCanonicalDecl() ==2968            Base->getCanonicalDecl())2969          DerivedToBasePath.push_back(&BS);2970      PrevRD = PathElem;2971    }2972    assert(DerivedToBasePath.size() == MemberPointerPath.size());2973 2974    CastKind CK = DerivedMember ? CK_DerivedToBaseMemberPointer2975                                : CK_BaseToDerivedMemberPointer;2976    C = EmitMemberPointerConversion(SrcTy, DstTy, CK, DerivedToBasePath.begin(),2977                                    DerivedToBasePath.end(), C);2978  }2979  return C;2980}2981 2982llvm::Constant *2983MicrosoftCXXABI::EmitMemberFunctionPointer(const CXXMethodDecl *MD) {2984  assert(MD->isInstance() && "Member function must not be static!");2985 2986  CharUnits NonVirtualBaseAdjustment = CharUnits::Zero();2987  const CXXRecordDecl *RD = MD->getParent()->getMostRecentDecl();2988  CodeGenTypes &Types = CGM.getTypes();2989 2990  unsigned VBTableIndex = 0;2991  llvm::Constant *FirstField;2992  const FunctionProtoType *FPT = MD->getType()->castAs<FunctionProtoType>();2993  if (!MD->isVirtual()) {2994    llvm::Type *Ty;2995    // Check whether the function has a computable LLVM signature.2996    if (Types.isFuncTypeConvertible(FPT)) {2997      // The function has a computable LLVM signature; use the correct type.2998      Ty = Types.GetFunctionType(Types.arrangeCXXMethodDeclaration(MD));2999    } else {3000      // Use an arbitrary non-function type to tell GetAddrOfFunction that the3001      // function type is incomplete.3002      Ty = CGM.PtrDiffTy;3003    }3004    FirstField = CGM.GetAddrOfFunction(MD, Ty);3005  } else {3006    auto &VTableContext = CGM.getMicrosoftVTableContext();3007    MethodVFTableLocation ML = VTableContext.getMethodVFTableLocation(MD);3008    FirstField = EmitVirtualMemPtrThunk(MD, ML);3009    // Include the vfptr adjustment if the method is in a non-primary vftable.3010    NonVirtualBaseAdjustment += ML.VFPtrOffset;3011    if (ML.VBase)3012      VBTableIndex = VTableContext.getVBTableIndex(RD, ML.VBase) * 4;3013  }3014 3015  if (VBTableIndex == 0 &&3016      RD->getMSInheritanceModel() ==3017          MSInheritanceModel::Virtual)3018    NonVirtualBaseAdjustment -= getContext().getOffsetOfBaseWithVBPtr(RD);3019 3020  // The rest of the fields are common with data member pointers.3021  return EmitFullMemberPointer(FirstField, /*IsMemberFunction=*/true, RD,3022                               NonVirtualBaseAdjustment, VBTableIndex);3023}3024 3025/// Member pointers are the same if they're either bitwise identical *or* both3026/// null.  Null-ness for function members is determined by the first field,3027/// while for data member pointers we must compare all fields.3028llvm::Value *3029MicrosoftCXXABI::EmitMemberPointerComparison(CodeGenFunction &CGF,3030                                             llvm::Value *L,3031                                             llvm::Value *R,3032                                             const MemberPointerType *MPT,3033                                             bool Inequality) {3034  CGBuilderTy &Builder = CGF.Builder;3035 3036  // Handle != comparisons by switching the sense of all boolean operations.3037  llvm::ICmpInst::Predicate Eq;3038  llvm::Instruction::BinaryOps And, Or;3039  if (Inequality) {3040    Eq = llvm::ICmpInst::ICMP_NE;3041    And = llvm::Instruction::Or;3042    Or = llvm::Instruction::And;3043  } else {3044    Eq = llvm::ICmpInst::ICMP_EQ;3045    And = llvm::Instruction::And;3046    Or = llvm::Instruction::Or;3047  }3048 3049  // If this is a single field member pointer (single inheritance), this is a3050  // single icmp.3051  const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();3052  MSInheritanceModel Inheritance = RD->getMSInheritanceModel();3053  if (inheritanceModelHasOnlyOneField(MPT->isMemberFunctionPointer(),3054                                      Inheritance))3055    return Builder.CreateICmp(Eq, L, R);3056 3057  // Compare the first field.3058  llvm::Value *L0 = Builder.CreateExtractValue(L, 0, "lhs.0");3059  llvm::Value *R0 = Builder.CreateExtractValue(R, 0, "rhs.0");3060  llvm::Value *Cmp0 = Builder.CreateICmp(Eq, L0, R0, "memptr.cmp.first");3061 3062  // Compare everything other than the first field.3063  llvm::Value *Res = nullptr;3064  llvm::StructType *LType = cast<llvm::StructType>(L->getType());3065  for (unsigned I = 1, E = LType->getNumElements(); I != E; ++I) {3066    llvm::Value *LF = Builder.CreateExtractValue(L, I);3067    llvm::Value *RF = Builder.CreateExtractValue(R, I);3068    llvm::Value *Cmp = Builder.CreateICmp(Eq, LF, RF, "memptr.cmp.rest");3069    if (Res)3070      Res = Builder.CreateBinOp(And, Res, Cmp);3071    else3072      Res = Cmp;3073  }3074 3075  // Check if the first field is 0 if this is a function pointer.3076  if (MPT->isMemberFunctionPointer()) {3077    // (l1 == r1 && ...) || l0 == 03078    llvm::Value *Zero = llvm::Constant::getNullValue(L0->getType());3079    llvm::Value *IsZero = Builder.CreateICmp(Eq, L0, Zero, "memptr.cmp.iszero");3080    Res = Builder.CreateBinOp(Or, Res, IsZero);3081  }3082 3083  // Combine the comparison of the first field, which must always be true for3084  // this comparison to succeeed.3085  return Builder.CreateBinOp(And, Res, Cmp0, "memptr.cmp");3086}3087 3088llvm::Value *3089MicrosoftCXXABI::EmitMemberPointerIsNotNull(CodeGenFunction &CGF,3090                                            llvm::Value *MemPtr,3091                                            const MemberPointerType *MPT) {3092  CGBuilderTy &Builder = CGF.Builder;3093  llvm::SmallVector<llvm::Constant *, 4> fields;3094  // We only need one field for member functions.3095  if (MPT->isMemberFunctionPointer())3096    fields.push_back(llvm::Constant::getNullValue(CGM.VoidPtrTy));3097  else3098    GetNullMemberPointerFields(MPT, fields);3099  assert(!fields.empty());3100  llvm::Value *FirstField = MemPtr;3101  if (MemPtr->getType()->isStructTy())3102    FirstField = Builder.CreateExtractValue(MemPtr, 0);3103  llvm::Value *Res = Builder.CreateICmpNE(FirstField, fields[0], "memptr.cmp0");3104 3105  // For function member pointers, we only need to test the function pointer3106  // field.  The other fields if any can be garbage.3107  if (MPT->isMemberFunctionPointer())3108    return Res;3109 3110  // Otherwise, emit a series of compares and combine the results.3111  for (int I = 1, E = fields.size(); I < E; ++I) {3112    llvm::Value *Field = Builder.CreateExtractValue(MemPtr, I);3113    llvm::Value *Next = Builder.CreateICmpNE(Field, fields[I], "memptr.cmp");3114    Res = Builder.CreateOr(Res, Next, "memptr.tobool");3115  }3116  return Res;3117}3118 3119bool MicrosoftCXXABI::MemberPointerConstantIsNull(const MemberPointerType *MPT,3120                                                  llvm::Constant *Val) {3121  // Function pointers are null if the pointer in the first field is null.3122  if (MPT->isMemberFunctionPointer()) {3123    llvm::Constant *FirstField = Val->getType()->isStructTy() ?3124      Val->getAggregateElement(0U) : Val;3125    return FirstField->isNullValue();3126  }3127 3128  // If it's not a function pointer and it's zero initializable, we can easily3129  // check zero.3130  if (isZeroInitializable(MPT) && Val->isNullValue())3131    return true;3132 3133  // Otherwise, break down all the fields for comparison.  Hopefully these3134  // little Constants are reused, while a big null struct might not be.3135  llvm::SmallVector<llvm::Constant *, 4> Fields;3136  GetNullMemberPointerFields(MPT, Fields);3137  if (Fields.size() == 1) {3138    assert(Val->getType()->isIntegerTy());3139    return Val == Fields[0];3140  }3141 3142  unsigned I, E;3143  for (I = 0, E = Fields.size(); I != E; ++I) {3144    if (Val->getAggregateElement(I) != Fields[I])3145      break;3146  }3147  return I == E;3148}3149 3150llvm::Value *3151MicrosoftCXXABI::GetVBaseOffsetFromVBPtr(CodeGenFunction &CGF,3152                                         Address This,3153                                         llvm::Value *VBPtrOffset,3154                                         llvm::Value *VBTableOffset,3155                                         llvm::Value **VBPtrOut) {3156  CGBuilderTy &Builder = CGF.Builder;3157  // Load the vbtable pointer from the vbptr in the instance.3158  llvm::Value *VBPtr = Builder.CreateInBoundsGEP(3159      CGM.Int8Ty, This.emitRawPointer(CGF), VBPtrOffset, "vbptr");3160  if (VBPtrOut)3161    *VBPtrOut = VBPtr;3162 3163  CharUnits VBPtrAlign;3164  if (auto CI = dyn_cast<llvm::ConstantInt>(VBPtrOffset)) {3165    VBPtrAlign = This.getAlignment().alignmentAtOffset(3166                                   CharUnits::fromQuantity(CI->getSExtValue()));3167  } else {3168    VBPtrAlign = CGF.getPointerAlign();3169  }3170 3171  llvm::Value *VBTable =3172      Builder.CreateAlignedLoad(CGM.DefaultPtrTy, VBPtr, VBPtrAlign, "vbtable");3173 3174  // Translate from byte offset to table index. It improves analyzability.3175  llvm::Value *VBTableIndex = Builder.CreateAShr(3176      VBTableOffset, llvm::ConstantInt::get(VBTableOffset->getType(), 2),3177      "vbtindex", /*isExact=*/true);3178 3179  // Load an i32 offset from the vb-table.3180  llvm::Value *VBaseOffs =3181      Builder.CreateInBoundsGEP(CGM.Int32Ty, VBTable, VBTableIndex);3182  return Builder.CreateAlignedLoad(CGM.Int32Ty, VBaseOffs,3183                                   CharUnits::fromQuantity(4), "vbase_offs");3184}3185 3186// Returns an adjusted base cast to i8*, since we do more address arithmetic on3187// it.3188llvm::Value *MicrosoftCXXABI::AdjustVirtualBase(3189    CodeGenFunction &CGF, const Expr *E, const CXXRecordDecl *RD,3190    Address Base, llvm::Value *VBTableOffset, llvm::Value *VBPtrOffset) {3191  CGBuilderTy &Builder = CGF.Builder;3192  Base = Base.withElementType(CGM.Int8Ty);3193  llvm::BasicBlock *OriginalBB = nullptr;3194  llvm::BasicBlock *SkipAdjustBB = nullptr;3195  llvm::BasicBlock *VBaseAdjustBB = nullptr;3196 3197  // In the unspecified inheritance model, there might not be a vbtable at all,3198  // in which case we need to skip the virtual base lookup.  If there is a3199  // vbtable, the first entry is a no-op entry that gives back the original3200  // base, so look for a virtual base adjustment offset of zero.3201  if (VBPtrOffset) {3202    OriginalBB = Builder.GetInsertBlock();3203    VBaseAdjustBB = CGF.createBasicBlock("memptr.vadjust");3204    SkipAdjustBB = CGF.createBasicBlock("memptr.skip_vadjust");3205    llvm::Value *IsVirtual =3206      Builder.CreateICmpNE(VBTableOffset, getZeroInt(),3207                           "memptr.is_vbase");3208    Builder.CreateCondBr(IsVirtual, VBaseAdjustBB, SkipAdjustBB);3209    CGF.EmitBlock(VBaseAdjustBB);3210  }3211 3212  // If we weren't given a dynamic vbptr offset, RD should be complete and we'll3213  // know the vbptr offset.3214  if (!VBPtrOffset) {3215    CharUnits offs = CharUnits::Zero();3216    if (!RD->hasDefinition()) {3217      DiagnosticsEngine &Diags = CGF.CGM.getDiags();3218      unsigned DiagID = Diags.getCustomDiagID(3219          DiagnosticsEngine::Error,3220          "member pointer representation requires a "3221          "complete class type for %0 to perform this expression");3222      Diags.Report(E->getExprLoc(), DiagID) << RD << E->getSourceRange();3223    } else if (RD->getNumVBases())3224      offs = getContext().getASTRecordLayout(RD).getVBPtrOffset();3225    VBPtrOffset = llvm::ConstantInt::get(CGM.IntTy, offs.getQuantity());3226  }3227  llvm::Value *VBPtr = nullptr;3228  llvm::Value *VBaseOffs =3229    GetVBaseOffsetFromVBPtr(CGF, Base, VBPtrOffset, VBTableOffset, &VBPtr);3230  llvm::Value *AdjustedBase =3231    Builder.CreateInBoundsGEP(CGM.Int8Ty, VBPtr, VBaseOffs);3232 3233  // Merge control flow with the case where we didn't have to adjust.3234  if (VBaseAdjustBB) {3235    Builder.CreateBr(SkipAdjustBB);3236    CGF.EmitBlock(SkipAdjustBB);3237    llvm::PHINode *Phi = Builder.CreatePHI(CGM.Int8PtrTy, 2, "memptr.base");3238    Phi->addIncoming(Base.emitRawPointer(CGF), OriginalBB);3239    Phi->addIncoming(AdjustedBase, VBaseAdjustBB);3240    return Phi;3241  }3242  return AdjustedBase;3243}3244 3245llvm::Value *MicrosoftCXXABI::EmitMemberDataPointerAddress(3246    CodeGenFunction &CGF, const Expr *E, Address Base, llvm::Value *MemPtr,3247    const MemberPointerType *MPT, bool IsInBounds) {3248  assert(MPT->isMemberDataPointer());3249  CGBuilderTy &Builder = CGF.Builder;3250  const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();3251  MSInheritanceModel Inheritance = RD->getMSInheritanceModel();3252 3253  // Extract the fields we need, regardless of model.  We'll apply them if we3254  // have them.3255  llvm::Value *FieldOffset = MemPtr;3256  llvm::Value *VirtualBaseAdjustmentOffset = nullptr;3257  llvm::Value *VBPtrOffset = nullptr;3258  if (MemPtr->getType()->isStructTy()) {3259    // We need to extract values.3260    unsigned I = 0;3261    FieldOffset = Builder.CreateExtractValue(MemPtr, I++);3262    if (inheritanceModelHasVBPtrOffsetField(Inheritance))3263      VBPtrOffset = Builder.CreateExtractValue(MemPtr, I++);3264    if (inheritanceModelHasVBTableOffsetField(Inheritance))3265      VirtualBaseAdjustmentOffset = Builder.CreateExtractValue(MemPtr, I++);3266  }3267 3268  llvm::Value *Addr;3269  if (VirtualBaseAdjustmentOffset) {3270    Addr = AdjustVirtualBase(CGF, E, RD, Base, VirtualBaseAdjustmentOffset,3271                             VBPtrOffset);3272  } else {3273    Addr = Base.emitRawPointer(CGF);3274  }3275 3276  // Apply the offset.3277  return Builder.CreateGEP(CGF.Int8Ty, Addr, FieldOffset, "memptr.offset",3278                           IsInBounds ? llvm::GEPNoWrapFlags::inBounds()3279                                      : llvm::GEPNoWrapFlags::none());3280}3281 3282llvm::Value *3283MicrosoftCXXABI::EmitMemberPointerConversion(CodeGenFunction &CGF,3284                                             const CastExpr *E,3285                                             llvm::Value *Src) {3286  assert(E->getCastKind() == CK_DerivedToBaseMemberPointer ||3287         E->getCastKind() == CK_BaseToDerivedMemberPointer ||3288         E->getCastKind() == CK_ReinterpretMemberPointer);3289 3290  // Use constant emission if we can.3291  if (isa<llvm::Constant>(Src))3292    return EmitMemberPointerConversion(E, cast<llvm::Constant>(Src));3293 3294  // We may be adding or dropping fields from the member pointer, so we need3295  // both types and the inheritance models of both records.3296  const MemberPointerType *SrcTy =3297    E->getSubExpr()->getType()->castAs<MemberPointerType>();3298  const MemberPointerType *DstTy = E->getType()->castAs<MemberPointerType>();3299  bool IsFunc = SrcTy->isMemberFunctionPointer();3300 3301  // If the classes use the same null representation, reinterpret_cast is a nop.3302  bool IsReinterpret = E->getCastKind() == CK_ReinterpretMemberPointer;3303  if (IsReinterpret && IsFunc)3304    return Src;3305 3306  CXXRecordDecl *SrcRD = SrcTy->getMostRecentCXXRecordDecl();3307  CXXRecordDecl *DstRD = DstTy->getMostRecentCXXRecordDecl();3308  if (IsReinterpret &&3309      SrcRD->nullFieldOffsetIsZero() == DstRD->nullFieldOffsetIsZero())3310    return Src;3311 3312  CGBuilderTy &Builder = CGF.Builder;3313 3314  // Branch past the conversion if Src is null.3315  llvm::Value *IsNotNull = EmitMemberPointerIsNotNull(CGF, Src, SrcTy);3316  llvm::Constant *DstNull = EmitNullMemberPointer(DstTy);3317 3318  // C++ 5.2.10p9: The null member pointer value is converted to the null member3319  //   pointer value of the destination type.3320  if (IsReinterpret) {3321    // For reinterpret casts, sema ensures that src and dst are both functions3322    // or data and have the same size, which means the LLVM types should match.3323    assert(Src->getType() == DstNull->getType());3324    return Builder.CreateSelect(IsNotNull, Src, DstNull);3325  }3326 3327  llvm::BasicBlock *OriginalBB = Builder.GetInsertBlock();3328  llvm::BasicBlock *ConvertBB = CGF.createBasicBlock("memptr.convert");3329  llvm::BasicBlock *ContinueBB = CGF.createBasicBlock("memptr.converted");3330  Builder.CreateCondBr(IsNotNull, ConvertBB, ContinueBB);3331  CGF.EmitBlock(ConvertBB);3332 3333  llvm::Value *Dst = EmitNonNullMemberPointerConversion(3334      SrcTy, DstTy, E->getCastKind(), E->path_begin(), E->path_end(), Src,3335      Builder);3336 3337  Builder.CreateBr(ContinueBB);3338 3339  // In the continuation, choose between DstNull and Dst.3340  CGF.EmitBlock(ContinueBB);3341  llvm::PHINode *Phi = Builder.CreatePHI(DstNull->getType(), 2, "memptr.converted");3342  Phi->addIncoming(DstNull, OriginalBB);3343  Phi->addIncoming(Dst, ConvertBB);3344  return Phi;3345}3346 3347llvm::Value *MicrosoftCXXABI::EmitNonNullMemberPointerConversion(3348    const MemberPointerType *SrcTy, const MemberPointerType *DstTy, CastKind CK,3349    CastExpr::path_const_iterator PathBegin,3350    CastExpr::path_const_iterator PathEnd, llvm::Value *Src,3351    CGBuilderTy &Builder) {3352  const CXXRecordDecl *SrcRD = SrcTy->getMostRecentCXXRecordDecl();3353  const CXXRecordDecl *DstRD = DstTy->getMostRecentCXXRecordDecl();3354  MSInheritanceModel SrcInheritance = SrcRD->getMSInheritanceModel();3355  MSInheritanceModel DstInheritance = DstRD->getMSInheritanceModel();3356  bool IsFunc = SrcTy->isMemberFunctionPointer();3357  bool IsConstant = isa<llvm::Constant>(Src);3358 3359  // Decompose src.3360  llvm::Value *FirstField = Src;3361  llvm::Value *NonVirtualBaseAdjustment = getZeroInt();3362  llvm::Value *VirtualBaseAdjustmentOffset = getZeroInt();3363  llvm::Value *VBPtrOffset = getZeroInt();3364  if (!inheritanceModelHasOnlyOneField(IsFunc, SrcInheritance)) {3365    // We need to extract values.3366    unsigned I = 0;3367    FirstField = Builder.CreateExtractValue(Src, I++);3368    if (inheritanceModelHasNVOffsetField(IsFunc, SrcInheritance))3369      NonVirtualBaseAdjustment = Builder.CreateExtractValue(Src, I++);3370    if (inheritanceModelHasVBPtrOffsetField(SrcInheritance))3371      VBPtrOffset = Builder.CreateExtractValue(Src, I++);3372    if (inheritanceModelHasVBTableOffsetField(SrcInheritance))3373      VirtualBaseAdjustmentOffset = Builder.CreateExtractValue(Src, I++);3374  }3375 3376  bool IsDerivedToBase = (CK == CK_DerivedToBaseMemberPointer);3377  const MemberPointerType *DerivedTy = IsDerivedToBase ? SrcTy : DstTy;3378  const CXXRecordDecl *DerivedClass = DerivedTy->getMostRecentCXXRecordDecl();3379 3380  // For data pointers, we adjust the field offset directly.  For functions, we3381  // have a separate field.3382  llvm::Value *&NVAdjustField = IsFunc ? NonVirtualBaseAdjustment : FirstField;3383 3384  // The virtual inheritance model has a quirk: the virtual base table is always3385  // referenced when dereferencing a member pointer even if the member pointer3386  // is non-virtual.  This is accounted for by adjusting the non-virtual offset3387  // to point backwards to the top of the MDC from the first VBase.  Undo this3388  // adjustment to normalize the member pointer.3389  llvm::Value *SrcVBIndexEqZero =3390      Builder.CreateICmpEQ(VirtualBaseAdjustmentOffset, getZeroInt());3391  if (SrcInheritance == MSInheritanceModel::Virtual) {3392    if (int64_t SrcOffsetToFirstVBase =3393            getContext().getOffsetOfBaseWithVBPtr(SrcRD).getQuantity()) {3394      llvm::Value *UndoSrcAdjustment = Builder.CreateSelect(3395          SrcVBIndexEqZero,3396          llvm::ConstantInt::get(CGM.IntTy, SrcOffsetToFirstVBase),3397          getZeroInt());3398      NVAdjustField = Builder.CreateNSWAdd(NVAdjustField, UndoSrcAdjustment);3399    }3400  }3401 3402  // A non-zero vbindex implies that we are dealing with a source member in a3403  // floating virtual base in addition to some non-virtual offset.  If the3404  // vbindex is zero, we are dealing with a source that exists in a non-virtual,3405  // fixed, base.  The difference between these two cases is that the vbindex +3406  // nvoffset *always* point to the member regardless of what context they are3407  // evaluated in so long as the vbindex is adjusted.  A member inside a fixed3408  // base requires explicit nv adjustment.3409  llvm::Constant *BaseClassOffset = llvm::ConstantInt::get(3410      CGM.IntTy,3411      CGM.computeNonVirtualBaseClassOffset(DerivedClass, PathBegin, PathEnd)3412          .getQuantity());3413 3414  llvm::Value *NVDisp;3415  if (IsDerivedToBase)3416    NVDisp = Builder.CreateNSWSub(NVAdjustField, BaseClassOffset, "adj");3417  else3418    NVDisp = Builder.CreateNSWAdd(NVAdjustField, BaseClassOffset, "adj");3419 3420  NVAdjustField = Builder.CreateSelect(SrcVBIndexEqZero, NVDisp, getZeroInt());3421 3422  // Update the vbindex to an appropriate value in the destination because3423  // SrcRD's vbtable might not be a strict prefix of the one in DstRD.3424  llvm::Value *DstVBIndexEqZero = SrcVBIndexEqZero;3425  if (inheritanceModelHasVBTableOffsetField(DstInheritance) &&3426      inheritanceModelHasVBTableOffsetField(SrcInheritance)) {3427    if (llvm::GlobalVariable *VDispMap =3428            getAddrOfVirtualDisplacementMap(SrcRD, DstRD)) {3429      llvm::Value *VBIndex = Builder.CreateExactUDiv(3430          VirtualBaseAdjustmentOffset, llvm::ConstantInt::get(CGM.IntTy, 4));3431      if (IsConstant) {3432        llvm::Constant *Mapping = VDispMap->getInitializer();3433        VirtualBaseAdjustmentOffset =3434            Mapping->getAggregateElement(cast<llvm::Constant>(VBIndex));3435      } else {3436        llvm::Value *Idxs[] = {getZeroInt(), VBIndex};3437        VirtualBaseAdjustmentOffset = Builder.CreateAlignedLoad(3438            CGM.IntTy, Builder.CreateInBoundsGEP(VDispMap->getValueType(),3439                                                 VDispMap, Idxs),3440            CharUnits::fromQuantity(4));3441      }3442 3443      DstVBIndexEqZero =3444          Builder.CreateICmpEQ(VirtualBaseAdjustmentOffset, getZeroInt());3445    }3446  }3447 3448  // Set the VBPtrOffset to zero if the vbindex is zero.  Otherwise, initialize3449  // it to the offset of the vbptr.3450  if (inheritanceModelHasVBPtrOffsetField(DstInheritance)) {3451    llvm::Value *DstVBPtrOffset = llvm::ConstantInt::get(3452        CGM.IntTy,3453        getContext().getASTRecordLayout(DstRD).getVBPtrOffset().getQuantity());3454    VBPtrOffset =3455        Builder.CreateSelect(DstVBIndexEqZero, getZeroInt(), DstVBPtrOffset);3456  }3457 3458  // Likewise, apply a similar adjustment so that dereferencing the member3459  // pointer correctly accounts for the distance between the start of the first3460  // virtual base and the top of the MDC.3461  if (DstInheritance == MSInheritanceModel::Virtual) {3462    if (int64_t DstOffsetToFirstVBase =3463            getContext().getOffsetOfBaseWithVBPtr(DstRD).getQuantity()) {3464      llvm::Value *DoDstAdjustment = Builder.CreateSelect(3465          DstVBIndexEqZero,3466          llvm::ConstantInt::get(CGM.IntTy, DstOffsetToFirstVBase),3467          getZeroInt());3468      NVAdjustField = Builder.CreateNSWSub(NVAdjustField, DoDstAdjustment);3469    }3470  }3471 3472  // Recompose dst from the null struct and the adjusted fields from src.3473  llvm::Value *Dst;3474  if (inheritanceModelHasOnlyOneField(IsFunc, DstInheritance)) {3475    Dst = FirstField;3476  } else {3477    Dst = llvm::PoisonValue::get(ConvertMemberPointerType(DstTy));3478    unsigned Idx = 0;3479    Dst = Builder.CreateInsertValue(Dst, FirstField, Idx++);3480    if (inheritanceModelHasNVOffsetField(IsFunc, DstInheritance))3481      Dst = Builder.CreateInsertValue(Dst, NonVirtualBaseAdjustment, Idx++);3482    if (inheritanceModelHasVBPtrOffsetField(DstInheritance))3483      Dst = Builder.CreateInsertValue(Dst, VBPtrOffset, Idx++);3484    if (inheritanceModelHasVBTableOffsetField(DstInheritance))3485      Dst = Builder.CreateInsertValue(Dst, VirtualBaseAdjustmentOffset, Idx++);3486  }3487  return Dst;3488}3489 3490llvm::Constant *3491MicrosoftCXXABI::EmitMemberPointerConversion(const CastExpr *E,3492                                             llvm::Constant *Src) {3493  const MemberPointerType *SrcTy =3494      E->getSubExpr()->getType()->castAs<MemberPointerType>();3495  const MemberPointerType *DstTy = E->getType()->castAs<MemberPointerType>();3496 3497  CastKind CK = E->getCastKind();3498 3499  return EmitMemberPointerConversion(SrcTy, DstTy, CK, E->path_begin(),3500                                     E->path_end(), Src);3501}3502 3503llvm::Constant *MicrosoftCXXABI::EmitMemberPointerConversion(3504    const MemberPointerType *SrcTy, const MemberPointerType *DstTy, CastKind CK,3505    CastExpr::path_const_iterator PathBegin,3506    CastExpr::path_const_iterator PathEnd, llvm::Constant *Src) {3507  assert(CK == CK_DerivedToBaseMemberPointer ||3508         CK == CK_BaseToDerivedMemberPointer ||3509         CK == CK_ReinterpretMemberPointer);3510  // If src is null, emit a new null for dst.  We can't return src because dst3511  // might have a new representation.3512  if (MemberPointerConstantIsNull(SrcTy, Src))3513    return EmitNullMemberPointer(DstTy);3514 3515  // We don't need to do anything for reinterpret_casts of non-null member3516  // pointers.  We should only get here when the two type representations have3517  // the same size.3518  if (CK == CK_ReinterpretMemberPointer)3519    return Src;3520 3521  CGBuilderTy Builder(CGM, CGM.getLLVMContext());3522  auto *Dst = cast<llvm::Constant>(EmitNonNullMemberPointerConversion(3523      SrcTy, DstTy, CK, PathBegin, PathEnd, Src, Builder));3524 3525  return Dst;3526}3527 3528CGCallee MicrosoftCXXABI::EmitLoadOfMemberFunctionPointer(3529    CodeGenFunction &CGF, const Expr *E, Address This,3530    llvm::Value *&ThisPtrForCall, llvm::Value *MemPtr,3531    const MemberPointerType *MPT) {3532  assert(MPT->isMemberFunctionPointer());3533  const FunctionProtoType *FPT =3534    MPT->getPointeeType()->castAs<FunctionProtoType>();3535  const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();3536  CGBuilderTy &Builder = CGF.Builder;3537 3538  MSInheritanceModel Inheritance = RD->getMSInheritanceModel();3539 3540  // Extract the fields we need, regardless of model.  We'll apply them if we3541  // have them.3542  llvm::Value *FunctionPointer = MemPtr;3543  llvm::Value *NonVirtualBaseAdjustment = nullptr;3544  llvm::Value *VirtualBaseAdjustmentOffset = nullptr;3545  llvm::Value *VBPtrOffset = nullptr;3546  if (MemPtr->getType()->isStructTy()) {3547    // We need to extract values.3548    unsigned I = 0;3549    FunctionPointer = Builder.CreateExtractValue(MemPtr, I++);3550    if (inheritanceModelHasNVOffsetField(MPT, Inheritance))3551      NonVirtualBaseAdjustment = Builder.CreateExtractValue(MemPtr, I++);3552    if (inheritanceModelHasVBPtrOffsetField(Inheritance))3553      VBPtrOffset = Builder.CreateExtractValue(MemPtr, I++);3554    if (inheritanceModelHasVBTableOffsetField(Inheritance))3555      VirtualBaseAdjustmentOffset = Builder.CreateExtractValue(MemPtr, I++);3556  }3557 3558  if (VirtualBaseAdjustmentOffset) {3559    ThisPtrForCall = AdjustVirtualBase(CGF, E, RD, This,3560                                   VirtualBaseAdjustmentOffset, VBPtrOffset);3561  } else {3562    ThisPtrForCall = This.emitRawPointer(CGF);3563  }3564 3565  if (NonVirtualBaseAdjustment)3566    ThisPtrForCall = Builder.CreateInBoundsGEP(CGF.Int8Ty, ThisPtrForCall,3567                                               NonVirtualBaseAdjustment);3568 3569  CGCallee Callee(FPT, FunctionPointer);3570  return Callee;3571}3572 3573CGCXXABI *clang::CodeGen::CreateMicrosoftCXXABI(CodeGenModule &CGM) {3574  return new MicrosoftCXXABI(CGM);3575}3576 3577// MS RTTI Overview:3578// The run time type information emitted by cl.exe contains 5 distinct types of3579// structures.  Many of them reference each other.3580//3581// TypeInfo:  Static classes that are returned by typeid.3582//3583// CompleteObjectLocator:  Referenced by vftables.  They contain information3584//   required for dynamic casting, including OffsetFromTop.  They also contain3585//   a reference to the TypeInfo for the type and a reference to the3586//   CompleteHierarchyDescriptor for the type.3587//3588// ClassHierarchyDescriptor: Contains information about a class hierarchy.3589//   Used during dynamic_cast to walk a class hierarchy.  References a base3590//   class array and the size of said array.3591//3592// BaseClassArray: Contains a list of classes in a hierarchy.  BaseClassArray is3593//   somewhat of a misnomer because the most derived class is also in the list3594//   as well as multiple copies of virtual bases (if they occur multiple times3595//   in the hierarchy.)  The BaseClassArray contains one BaseClassDescriptor for3596//   every path in the hierarchy, in pre-order depth first order.  Note, we do3597//   not declare a specific llvm type for BaseClassArray, it's merely an array3598//   of BaseClassDescriptor pointers.3599//3600// BaseClassDescriptor: Contains information about a class in a class hierarchy.3601//   BaseClassDescriptor is also somewhat of a misnomer for the same reason that3602//   BaseClassArray is.  It contains information about a class within a3603//   hierarchy such as: is this base is ambiguous and what is its offset in the3604//   vbtable.  The names of the BaseClassDescriptors have all of their fields3605//   mangled into them so they can be aggressively deduplicated by the linker.3606 3607static llvm::GlobalVariable *getTypeInfoVTable(CodeGenModule &CGM) {3608  StringRef MangledName("??_7type_info@@6B@");3609  if (auto VTable = CGM.getModule().getNamedGlobal(MangledName))3610    return VTable;3611  return new llvm::GlobalVariable(CGM.getModule(), CGM.Int8PtrTy,3612                                  /*isConstant=*/true,3613                                  llvm::GlobalVariable::ExternalLinkage,3614                                  /*Initializer=*/nullptr, MangledName);3615}3616 3617namespace {3618 3619/// A Helper struct that stores information about a class in a class3620/// hierarchy.  The information stored in these structs struct is used during3621/// the generation of ClassHierarchyDescriptors and BaseClassDescriptors.3622// During RTTI creation, MSRTTIClasses are stored in a contiguous array with3623// implicit depth first pre-order tree connectivity.  getFirstChild and3624// getNextSibling allow us to walk the tree efficiently.3625struct MSRTTIClass {3626  enum {3627    IsPrivateOnPath = 1 | 8,3628    IsAmbiguous = 2,3629    IsPrivate = 4,3630    IsVirtual = 16,3631    HasHierarchyDescriptor = 643632  };3633  MSRTTIClass(const CXXRecordDecl *RD) : RD(RD) {}3634  uint32_t initialize(const MSRTTIClass *Parent,3635                      const CXXBaseSpecifier *Specifier);3636 3637  MSRTTIClass *getFirstChild() { return this + 1; }3638  static MSRTTIClass *getNextChild(MSRTTIClass *Child) {3639    return Child + 1 + Child->NumBases;3640  }3641 3642  const CXXRecordDecl *RD, *VirtualRoot;3643  uint32_t Flags, NumBases, OffsetInVBase;3644};3645 3646/// Recursively initialize the base class array.3647uint32_t MSRTTIClass::initialize(const MSRTTIClass *Parent,3648                                 const CXXBaseSpecifier *Specifier) {3649  Flags = HasHierarchyDescriptor;3650  if (!Parent) {3651    VirtualRoot = nullptr;3652    OffsetInVBase = 0;3653  } else {3654    if (Specifier->getAccessSpecifier() != AS_public)3655      Flags |= IsPrivate | IsPrivateOnPath;3656    if (Specifier->isVirtual()) {3657      Flags |= IsVirtual;3658      VirtualRoot = RD;3659      OffsetInVBase = 0;3660    } else {3661      if (Parent->Flags & IsPrivateOnPath)3662        Flags |= IsPrivateOnPath;3663      VirtualRoot = Parent->VirtualRoot;3664      OffsetInVBase = Parent->OffsetInVBase + RD->getASTContext()3665          .getASTRecordLayout(Parent->RD).getBaseClassOffset(RD).getQuantity();3666    }3667  }3668  NumBases = 0;3669  MSRTTIClass *Child = getFirstChild();3670  for (const CXXBaseSpecifier &Base : RD->bases()) {3671    NumBases += Child->initialize(this, &Base) + 1;3672    Child = getNextChild(Child);3673  }3674  return NumBases;3675}3676 3677static llvm::GlobalValue::LinkageTypes getLinkageForRTTI(QualType Ty) {3678  switch (Ty->getLinkage()) {3679  case Linkage::Invalid:3680    llvm_unreachable("Linkage hasn't been computed!");3681 3682  case Linkage::None:3683  case Linkage::Internal:3684  case Linkage::UniqueExternal:3685    return llvm::GlobalValue::InternalLinkage;3686 3687  case Linkage::VisibleNone:3688  case Linkage::Module:3689  case Linkage::External:3690    return llvm::GlobalValue::LinkOnceODRLinkage;3691  }3692  llvm_unreachable("Invalid linkage!");3693}3694 3695/// An ephemeral helper class for building MS RTTI types.  It caches some3696/// calls to the module and information about the most derived class in a3697/// hierarchy.3698struct MSRTTIBuilder {3699  enum {3700    HasBranchingHierarchy = 1,3701    HasVirtualBranchingHierarchy = 2,3702    HasAmbiguousBases = 43703  };3704 3705  MSRTTIBuilder(MicrosoftCXXABI &ABI, const CXXRecordDecl *RD)3706      : CGM(ABI.CGM), Context(CGM.getContext()),3707        VMContext(CGM.getLLVMContext()), Module(CGM.getModule()), RD(RD),3708        Linkage(getLinkageForRTTI(CGM.getContext().getCanonicalTagType(RD))),3709        ABI(ABI) {}3710 3711  llvm::GlobalVariable *getBaseClassDescriptor(const MSRTTIClass &Classes);3712  llvm::GlobalVariable *3713  getBaseClassArray(SmallVectorImpl<MSRTTIClass> &Classes);3714  llvm::GlobalVariable *getClassHierarchyDescriptor();3715  llvm::GlobalVariable *getCompleteObjectLocator(const VPtrInfo &Info);3716 3717  CodeGenModule &CGM;3718  ASTContext &Context;3719  llvm::LLVMContext &VMContext;3720  llvm::Module &Module;3721  const CXXRecordDecl *RD;3722  llvm::GlobalVariable::LinkageTypes Linkage;3723  MicrosoftCXXABI &ABI;3724};3725 3726} // namespace3727 3728/// Recursively serializes a class hierarchy in pre-order depth first3729/// order.3730static void serializeClassHierarchy(SmallVectorImpl<MSRTTIClass> &Classes,3731                                    const CXXRecordDecl *RD) {3732  Classes.push_back(MSRTTIClass(RD));3733  for (const CXXBaseSpecifier &Base : RD->bases())3734    serializeClassHierarchy(Classes, Base.getType()->getAsCXXRecordDecl());3735}3736 3737/// Find ambiguity among base classes.3738static void3739detectAmbiguousBases(SmallVectorImpl<MSRTTIClass> &Classes) {3740  llvm::SmallPtrSet<const CXXRecordDecl *, 8> VirtualBases;3741  llvm::SmallPtrSet<const CXXRecordDecl *, 8> UniqueBases;3742  llvm::SmallPtrSet<const CXXRecordDecl *, 8> AmbiguousBases;3743  for (MSRTTIClass *Class = &Classes.front(); Class <= &Classes.back();) {3744    if ((Class->Flags & MSRTTIClass::IsVirtual) &&3745        !VirtualBases.insert(Class->RD).second) {3746      Class = MSRTTIClass::getNextChild(Class);3747      continue;3748    }3749    if (!UniqueBases.insert(Class->RD).second)3750      AmbiguousBases.insert(Class->RD);3751    Class++;3752  }3753  if (AmbiguousBases.empty())3754    return;3755  for (MSRTTIClass &Class : Classes)3756    if (AmbiguousBases.count(Class.RD))3757      Class.Flags |= MSRTTIClass::IsAmbiguous;3758}3759 3760llvm::GlobalVariable *MSRTTIBuilder::getClassHierarchyDescriptor() {3761  SmallString<256> MangledName;3762  {3763    llvm::raw_svector_ostream Out(MangledName);3764    ABI.getMangleContext().mangleCXXRTTIClassHierarchyDescriptor(RD, Out);3765  }3766 3767  // Check to see if we've already declared this ClassHierarchyDescriptor.3768  if (auto CHD = Module.getNamedGlobal(MangledName))3769    return CHD;3770 3771  // Serialize the class hierarchy and initialize the CHD Fields.3772  SmallVector<MSRTTIClass, 8> Classes;3773  serializeClassHierarchy(Classes, RD);3774  Classes.front().initialize(/*Parent=*/nullptr, /*Specifier=*/nullptr);3775  detectAmbiguousBases(Classes);3776  int Flags = 0;3777  for (const MSRTTIClass &Class : Classes) {3778    if (Class.RD->getNumBases() > 1)3779      Flags |= HasBranchingHierarchy;3780    // Note: cl.exe does not calculate "HasAmbiguousBases" correctly.  We3781    // believe the field isn't actually used.3782    if (Class.Flags & MSRTTIClass::IsAmbiguous)3783      Flags |= HasAmbiguousBases;3784  }3785  if ((Flags & HasBranchingHierarchy) && RD->getNumVBases() != 0)3786    Flags |= HasVirtualBranchingHierarchy;3787  // These gep indices are used to get the address of the first element of the3788  // base class array.3789  llvm::Value *GEPIndices[] = {llvm::ConstantInt::get(CGM.IntTy, 0),3790                               llvm::ConstantInt::get(CGM.IntTy, 0)};3791 3792  // Forward-declare the class hierarchy descriptor3793  auto Type = ABI.getClassHierarchyDescriptorType();3794  auto CHD = new llvm::GlobalVariable(Module, Type, /*isConstant=*/true, Linkage,3795                                      /*Initializer=*/nullptr,3796                                      MangledName);3797  if (CHD->isWeakForLinker())3798    CHD->setComdat(CGM.getModule().getOrInsertComdat(CHD->getName()));3799 3800  auto *Bases = getBaseClassArray(Classes);3801 3802  // Initialize the base class ClassHierarchyDescriptor.3803  llvm::Constant *Fields[] = {3804      llvm::ConstantInt::get(CGM.IntTy, 0), // reserved by the runtime3805      llvm::ConstantInt::get(CGM.IntTy, Flags),3806      llvm::ConstantInt::get(CGM.IntTy, Classes.size()),3807      ABI.getImageRelativeConstant(llvm::ConstantExpr::getInBoundsGetElementPtr(3808          Bases->getValueType(), Bases,3809          llvm::ArrayRef<llvm::Value *>(GEPIndices))),3810  };3811  CHD->setInitializer(llvm::ConstantStruct::get(Type, Fields));3812  return CHD;3813}3814 3815llvm::GlobalVariable *3816MSRTTIBuilder::getBaseClassArray(SmallVectorImpl<MSRTTIClass> &Classes) {3817  SmallString<256> MangledName;3818  {3819    llvm::raw_svector_ostream Out(MangledName);3820    ABI.getMangleContext().mangleCXXRTTIBaseClassArray(RD, Out);3821  }3822 3823  // Forward-declare the base class array.3824  // cl.exe pads the base class array with 1 (in 32 bit mode) or 4 (in 64 bit3825  // mode) bytes of padding.  We provide a pointer sized amount of padding by3826  // adding +1 to Classes.size().  The sections have pointer alignment and are3827  // marked pick-any so it shouldn't matter.3828  llvm::Type *PtrType = ABI.getImageRelativeType(CGM.DefaultPtrTy);3829  auto *ArrType = llvm::ArrayType::get(PtrType, Classes.size() + 1);3830  auto *BCA =3831      new llvm::GlobalVariable(Module, ArrType,3832                               /*isConstant=*/true, Linkage,3833                               /*Initializer=*/nullptr, MangledName);3834  if (BCA->isWeakForLinker())3835    BCA->setComdat(CGM.getModule().getOrInsertComdat(BCA->getName()));3836 3837  // Initialize the BaseClassArray.3838  SmallVector<llvm::Constant *, 8> BaseClassArrayData;3839  for (MSRTTIClass &Class : Classes)3840    BaseClassArrayData.push_back(3841        ABI.getImageRelativeConstant(getBaseClassDescriptor(Class)));3842  BaseClassArrayData.push_back(llvm::Constant::getNullValue(PtrType));3843  BCA->setInitializer(llvm::ConstantArray::get(ArrType, BaseClassArrayData));3844  return BCA;3845}3846 3847llvm::GlobalVariable *3848MSRTTIBuilder::getBaseClassDescriptor(const MSRTTIClass &Class) {3849  // Compute the fields for the BaseClassDescriptor.  They are computed up front3850  // because they are mangled into the name of the object.3851  uint32_t OffsetInVBTable = 0;3852  int32_t VBPtrOffset = -1;3853  if (Class.VirtualRoot) {3854    auto &VTableContext = CGM.getMicrosoftVTableContext();3855    OffsetInVBTable = VTableContext.getVBTableIndex(RD, Class.VirtualRoot) * 4;3856    VBPtrOffset = Context.getASTRecordLayout(RD).getVBPtrOffset().getQuantity();3857  }3858 3859  SmallString<256> MangledName;3860  {3861    llvm::raw_svector_ostream Out(MangledName);3862    ABI.getMangleContext().mangleCXXRTTIBaseClassDescriptor(3863        Class.RD, Class.OffsetInVBase, VBPtrOffset, OffsetInVBTable,3864        Class.Flags, Out);3865  }3866 3867  // Check to see if we've already declared this object.3868  if (auto BCD = Module.getNamedGlobal(MangledName))3869    return BCD;3870 3871  // Forward-declare the base class descriptor.3872  auto Type = ABI.getBaseClassDescriptorType();3873  auto BCD =3874      new llvm::GlobalVariable(Module, Type, /*isConstant=*/true, Linkage,3875                               /*Initializer=*/nullptr, MangledName);3876  if (BCD->isWeakForLinker())3877    BCD->setComdat(CGM.getModule().getOrInsertComdat(BCD->getName()));3878 3879  // Initialize the BaseClassDescriptor.3880  llvm::Constant *Fields[] = {3881      ABI.getImageRelativeConstant(3882          ABI.getAddrOfRTTIDescriptor(Context.getCanonicalTagType(Class.RD))),3883      llvm::ConstantInt::get(CGM.IntTy, Class.NumBases),3884      llvm::ConstantInt::get(CGM.IntTy, Class.OffsetInVBase),3885      llvm::ConstantInt::get(CGM.IntTy, VBPtrOffset),3886      llvm::ConstantInt::get(CGM.IntTy, OffsetInVBTable),3887      llvm::ConstantInt::get(CGM.IntTy, Class.Flags),3888      ABI.getImageRelativeConstant(3889          MSRTTIBuilder(ABI, Class.RD).getClassHierarchyDescriptor()),3890  };3891  BCD->setInitializer(llvm::ConstantStruct::get(Type, Fields));3892  return BCD;3893}3894 3895llvm::GlobalVariable *3896MSRTTIBuilder::getCompleteObjectLocator(const VPtrInfo &Info) {3897  SmallString<256> MangledName;3898  {3899    llvm::raw_svector_ostream Out(MangledName);3900    ABI.getMangleContext().mangleCXXRTTICompleteObjectLocator(RD, Info.MangledPath, Out);3901  }3902 3903  // Check to see if we've already computed this complete object locator.3904  if (auto COL = Module.getNamedGlobal(MangledName))3905    return COL;3906 3907  // Compute the fields of the complete object locator.3908  int OffsetToTop = Info.FullOffsetInMDC.getQuantity();3909  int VFPtrOffset = 0;3910  // The offset includes the vtordisp if one exists.3911  if (const CXXRecordDecl *VBase = Info.getVBaseWithVPtr())3912    if (Context.getASTRecordLayout(RD)3913      .getVBaseOffsetsMap()3914      .find(VBase)3915      ->second.hasVtorDisp())3916      VFPtrOffset = Info.NonVirtualOffset.getQuantity() + 4;3917 3918  // Forward-declare the complete object locator.3919  llvm::StructType *Type = ABI.getCompleteObjectLocatorType();3920  auto COL = new llvm::GlobalVariable(Module, Type, /*isConstant=*/true, Linkage,3921    /*Initializer=*/nullptr, MangledName);3922 3923  // Initialize the CompleteObjectLocator.3924  llvm::Constant *Fields[] = {3925      llvm::ConstantInt::get(CGM.IntTy, ABI.isImageRelative()),3926      llvm::ConstantInt::get(CGM.IntTy, OffsetToTop),3927      llvm::ConstantInt::get(CGM.IntTy, VFPtrOffset),3928      ABI.getImageRelativeConstant(3929          CGM.GetAddrOfRTTIDescriptor(Context.getCanonicalTagType(RD))),3930      ABI.getImageRelativeConstant(getClassHierarchyDescriptor()),3931      ABI.getImageRelativeConstant(COL),3932  };3933  llvm::ArrayRef<llvm::Constant *> FieldsRef(Fields);3934  if (!ABI.isImageRelative())3935    FieldsRef = FieldsRef.drop_back();3936  COL->setInitializer(llvm::ConstantStruct::get(Type, FieldsRef));3937  if (COL->isWeakForLinker())3938    COL->setComdat(CGM.getModule().getOrInsertComdat(COL->getName()));3939  return COL;3940}3941 3942static QualType decomposeTypeForEH(ASTContext &Context, QualType T,3943                                   bool &IsConst, bool &IsVolatile,3944                                   bool &IsUnaligned) {3945  T = Context.getExceptionObjectType(T);3946 3947  // C++14 [except.handle]p3:3948  //   A handler is a match for an exception object of type E if [...]3949  //     - the handler is of type cv T or const T& where T is a pointer type and3950  //       E is a pointer type that can be converted to T by [...]3951  //         - a qualification conversion3952  IsConst = false;3953  IsVolatile = false;3954  IsUnaligned = false;3955  QualType PointeeType = T->getPointeeType();3956  if (!PointeeType.isNull()) {3957    IsConst = PointeeType.isConstQualified();3958    IsVolatile = PointeeType.isVolatileQualified();3959    IsUnaligned = PointeeType.getQualifiers().hasUnaligned();3960  }3961 3962  // Member pointer types like "const int A::*" are represented by having RTTI3963  // for "int A::*" and separately storing the const qualifier.3964  if (const auto *MPTy = T->getAs<MemberPointerType>())3965    T = Context.getMemberPointerType(PointeeType.getUnqualifiedType(),3966                                     MPTy->getQualifier(),3967                                     MPTy->getMostRecentCXXRecordDecl());3968 3969  // Pointer types like "const int * const *" are represented by having RTTI3970  // for "const int **" and separately storing the const qualifier.3971  if (T->isPointerType())3972    T = Context.getPointerType(PointeeType.getUnqualifiedType());3973 3974  return T;3975}3976 3977CatchTypeInfo3978MicrosoftCXXABI::getAddrOfCXXCatchHandlerType(QualType Type,3979                                              QualType CatchHandlerType) {3980  // TypeDescriptors for exceptions never have qualified pointer types,3981  // qualifiers are stored separately in order to support qualification3982  // conversions.3983  bool IsConst, IsVolatile, IsUnaligned;3984  Type =3985      decomposeTypeForEH(getContext(), Type, IsConst, IsVolatile, IsUnaligned);3986 3987  bool IsReference = CatchHandlerType->isReferenceType();3988 3989  uint32_t Flags = 0;3990  if (IsConst)3991    Flags |= 1;3992  if (IsVolatile)3993    Flags |= 2;3994  if (IsUnaligned)3995    Flags |= 4;3996  if (IsReference)3997    Flags |= 8;3998 3999  return CatchTypeInfo{getAddrOfRTTIDescriptor(Type)->stripPointerCasts(),4000                       Flags};4001}4002 4003/// Gets a TypeDescriptor.  Returns a llvm::Constant * rather than a4004/// llvm::GlobalVariable * because different type descriptors have different4005/// types, and need to be abstracted.  They are abstracting by casting the4006/// address to an Int8PtrTy.4007llvm::Constant *MicrosoftCXXABI::getAddrOfRTTIDescriptor(QualType Type) {4008  SmallString<256> MangledName;4009  {4010    llvm::raw_svector_ostream Out(MangledName);4011    getMangleContext().mangleCXXRTTI(Type, Out);4012  }4013 4014  // Check to see if we've already declared this TypeDescriptor.4015  if (llvm::GlobalVariable *GV = CGM.getModule().getNamedGlobal(MangledName))4016    return GV;4017 4018  // Note for the future: If we would ever like to do deferred emission of4019  // RTTI, check if emitting vtables opportunistically need any adjustment.4020 4021  // Compute the fields for the TypeDescriptor.4022  SmallString<256> TypeInfoString;4023  {4024    llvm::raw_svector_ostream Out(TypeInfoString);4025    getMangleContext().mangleCXXRTTIName(Type, Out);4026  }4027 4028  // Declare and initialize the TypeDescriptor.4029  llvm::Constant *Fields[] = {4030    getTypeInfoVTable(CGM),                        // VFPtr4031    llvm::ConstantPointerNull::get(CGM.Int8PtrTy), // Runtime data4032    llvm::ConstantDataArray::getString(CGM.getLLVMContext(), TypeInfoString)};4033  llvm::StructType *TypeDescriptorType =4034      getTypeDescriptorType(TypeInfoString);4035  auto *Var = new llvm::GlobalVariable(4036      CGM.getModule(), TypeDescriptorType, /*isConstant=*/false,4037      getLinkageForRTTI(Type),4038      llvm::ConstantStruct::get(TypeDescriptorType, Fields),4039      MangledName);4040  if (Var->isWeakForLinker())4041    Var->setComdat(CGM.getModule().getOrInsertComdat(Var->getName()));4042  return Var;4043}4044 4045/// Gets or a creates a Microsoft CompleteObjectLocator.4046llvm::GlobalVariable *4047MicrosoftCXXABI::getMSCompleteObjectLocator(const CXXRecordDecl *RD,4048                                            const VPtrInfo &Info) {4049  return MSRTTIBuilder(*this, RD).getCompleteObjectLocator(Info);4050}4051 4052void MicrosoftCXXABI::emitCXXStructor(GlobalDecl GD) {4053  if (auto *ctor = dyn_cast<CXXConstructorDecl>(GD.getDecl())) {4054    // There are no constructor variants, always emit the complete destructor.4055    llvm::Function *Fn =4056        CGM.codegenCXXStructor(GD.getWithCtorType(Ctor_Complete));4057    CGM.maybeSetTrivialComdat(*ctor, *Fn);4058    return;4059  }4060 4061  auto *dtor = cast<CXXDestructorDecl>(GD.getDecl());4062 4063  // Emit the base destructor if the base and complete (vbase) destructors are4064  // equivalent. This effectively implements -mconstructor-aliases as part of4065  // the ABI.4066  if (GD.getDtorType() == Dtor_Complete &&4067      dtor->getParent()->getNumVBases() == 0)4068    GD = GD.getWithDtorType(Dtor_Base);4069 4070  // The base destructor is equivalent to the base destructor of its4071  // base class if there is exactly one non-virtual base class with a4072  // non-trivial destructor, there are no fields with a non-trivial4073  // destructor, and the body of the destructor is trivial.4074  if (GD.getDtorType() == Dtor_Base && !CGM.TryEmitBaseDestructorAsAlias(dtor))4075    return;4076 4077  llvm::Function *Fn = CGM.codegenCXXStructor(GD);4078  if (Fn->isWeakForLinker())4079    Fn->setComdat(CGM.getModule().getOrInsertComdat(Fn->getName()));4080}4081 4082llvm::Function *4083MicrosoftCXXABI::getAddrOfCXXCtorClosure(const CXXConstructorDecl *CD,4084                                         CXXCtorType CT) {4085  assert(CT == Ctor_CopyingClosure || CT == Ctor_DefaultClosure);4086 4087  // Calculate the mangled name.4088  SmallString<256> ThunkName;4089  llvm::raw_svector_ostream Out(ThunkName);4090  getMangleContext().mangleName(GlobalDecl(CD, CT), Out);4091 4092  // If the thunk has been generated previously, just return it.4093  if (llvm::GlobalValue *GV = CGM.getModule().getNamedValue(ThunkName))4094    return cast<llvm::Function>(GV);4095 4096  // Create the llvm::Function.4097  const CGFunctionInfo &FnInfo = CGM.getTypes().arrangeMSCtorClosure(CD, CT);4098  llvm::FunctionType *ThunkTy = CGM.getTypes().GetFunctionType(FnInfo);4099  const CXXRecordDecl *RD = CD->getParent();4100  CanQualType RecordTy = getContext().getCanonicalTagType(RD);4101  llvm::Function *ThunkFn = llvm::Function::Create(4102      ThunkTy, getLinkageForRTTI(RecordTy), ThunkName.str(), &CGM.getModule());4103  ThunkFn->setCallingConv(static_cast<llvm::CallingConv::ID>(4104      FnInfo.getEffectiveCallingConvention()));4105  if (ThunkFn->isWeakForLinker())4106    ThunkFn->setComdat(CGM.getModule().getOrInsertComdat(ThunkFn->getName()));4107  bool IsCopy = CT == Ctor_CopyingClosure;4108 4109  // Start codegen.4110  CodeGenFunction CGF(CGM);4111  CGF.CurGD = GlobalDecl(CD, Ctor_Complete);4112 4113  // Build FunctionArgs.4114  FunctionArgList FunctionArgs;4115 4116  // A constructor always starts with a 'this' pointer as its first argument.4117  buildThisParam(CGF, FunctionArgs);4118 4119  // Following the 'this' pointer is a reference to the source object that we4120  // are copying from.4121  ImplicitParamDecl SrcParam(4122      getContext(), /*DC=*/nullptr, SourceLocation(),4123      &getContext().Idents.get("src"),4124      getContext().getLValueReferenceType(RecordTy,4125                                          /*SpelledAsLValue=*/true),4126      ImplicitParamKind::Other);4127  if (IsCopy)4128    FunctionArgs.push_back(&SrcParam);4129 4130  // Constructors for classes which utilize virtual bases have an additional4131  // parameter which indicates whether or not it is being delegated to by a more4132  // derived constructor.4133  ImplicitParamDecl IsMostDerived(getContext(), /*DC=*/nullptr,4134                                  SourceLocation(),4135                                  &getContext().Idents.get("is_most_derived"),4136                                  getContext().IntTy, ImplicitParamKind::Other);4137  // Only add the parameter to the list if the class has virtual bases.4138  if (RD->getNumVBases() > 0)4139    FunctionArgs.push_back(&IsMostDerived);4140 4141  // Start defining the function.4142  auto NL = ApplyDebugLocation::CreateEmpty(CGF);4143  CGF.StartFunction(GlobalDecl(), FnInfo.getReturnType(), ThunkFn, FnInfo,4144                    FunctionArgs, CD->getLocation(), SourceLocation());4145  // Create a scope with an artificial location for the body of this function.4146  auto AL = ApplyDebugLocation::CreateArtificial(CGF);4147  setCXXABIThisValue(CGF, loadIncomingCXXThis(CGF));4148  llvm::Value *This = getThisValue(CGF);4149 4150  llvm::Value *SrcVal =4151      IsCopy ? CGF.Builder.CreateLoad(CGF.GetAddrOfLocalVar(&SrcParam), "src")4152             : nullptr;4153 4154  CallArgList Args;4155 4156  // Push the this ptr.4157  Args.add(RValue::get(This), CD->getThisType());4158 4159  // Push the src ptr.4160  if (SrcVal)4161    Args.add(RValue::get(SrcVal), SrcParam.getType());4162 4163  // Add the rest of the default arguments.4164  SmallVector<const Stmt *, 4> ArgVec;4165  ArrayRef<ParmVarDecl *> params = CD->parameters().drop_front(IsCopy ? 1 : 0);4166  for (const ParmVarDecl *PD : params) {4167    assert(PD->hasDefaultArg() && "ctor closure lacks default args");4168    ArgVec.push_back(PD->getDefaultArg());4169  }4170 4171  CodeGenFunction::RunCleanupsScope Cleanups(CGF);4172 4173  const auto *FPT = CD->getType()->castAs<FunctionProtoType>();4174  CGF.EmitCallArgs(Args, FPT, llvm::ArrayRef(ArgVec), CD, IsCopy ? 1 : 0);4175 4176  // Insert any ABI-specific implicit constructor arguments.4177  AddedStructorArgCounts ExtraArgs =4178      addImplicitConstructorArgs(CGF, CD, Ctor_Complete,4179                                 /*ForVirtualBase=*/false,4180                                 /*Delegating=*/false, Args);4181  // Call the destructor with our arguments.4182  llvm::Constant *CalleePtr =4183      CGM.getAddrOfCXXStructor(GlobalDecl(CD, Ctor_Complete));4184  CGCallee Callee =4185      CGCallee::forDirect(CalleePtr, GlobalDecl(CD, Ctor_Complete));4186  const CGFunctionInfo &CalleeInfo = CGM.getTypes().arrangeCXXConstructorCall(4187      Args, CD, Ctor_Complete, ExtraArgs.Prefix, ExtraArgs.Suffix);4188  CGF.EmitCall(CalleeInfo, Callee, ReturnValueSlot(), Args);4189 4190  Cleanups.ForceCleanup();4191 4192  // Emit the ret instruction, remove any temporary instructions created for the4193  // aid of CodeGen.4194  CGF.FinishFunction(SourceLocation());4195 4196  return ThunkFn;4197}4198 4199llvm::Constant *MicrosoftCXXABI::getCatchableType(QualType T,4200                                                  uint32_t NVOffset,4201                                                  int32_t VBPtrOffset,4202                                                  uint32_t VBIndex) {4203  assert(!T->isReferenceType());4204 4205  CXXRecordDecl *RD = T->getAsCXXRecordDecl();4206  const CXXConstructorDecl *CD =4207      RD ? CGM.getContext().getCopyConstructorForExceptionObject(RD) : nullptr;4208  CXXCtorType CT = Ctor_Complete;4209  if (CD)4210    if (!hasDefaultCXXMethodCC(getContext(), CD) || CD->getNumParams() != 1)4211      CT = Ctor_CopyingClosure;4212 4213  uint32_t Size = getContext().getTypeSizeInChars(T).getQuantity();4214  SmallString<256> MangledName;4215  {4216    llvm::raw_svector_ostream Out(MangledName);4217    getMangleContext().mangleCXXCatchableType(T, CD, CT, Size, NVOffset,4218                                              VBPtrOffset, VBIndex, Out);4219  }4220  if (llvm::GlobalVariable *GV = CGM.getModule().getNamedGlobal(MangledName))4221    return getImageRelativeConstant(GV);4222 4223  // The TypeDescriptor is used by the runtime to determine if a catch handler4224  // is appropriate for the exception object.4225  llvm::Constant *TD = getImageRelativeConstant(getAddrOfRTTIDescriptor(T));4226 4227  // The runtime is responsible for calling the copy constructor if the4228  // exception is caught by value.4229  llvm::Constant *CopyCtor;4230  if (CD) {4231    if (CT == Ctor_CopyingClosure)4232      CopyCtor = getAddrOfCXXCtorClosure(CD, Ctor_CopyingClosure);4233    else4234      CopyCtor = CGM.getAddrOfCXXStructor(GlobalDecl(CD, Ctor_Complete));4235  } else {4236    CopyCtor = llvm::Constant::getNullValue(CGM.Int8PtrTy);4237  }4238  CopyCtor = getImageRelativeConstant(CopyCtor);4239 4240  bool IsScalar = !RD;4241  bool HasVirtualBases = false;4242  bool IsStdBadAlloc = false; // std::bad_alloc is special for some reason.4243  QualType PointeeType = T;4244  if (T->isPointerType())4245    PointeeType = T->getPointeeType();4246  if (const CXXRecordDecl *RD = PointeeType->getAsCXXRecordDecl()) {4247    HasVirtualBases = RD->getNumVBases() > 0;4248    if (IdentifierInfo *II = RD->getIdentifier())4249      IsStdBadAlloc = II->isStr("bad_alloc") && RD->isInStdNamespace();4250  }4251 4252  // Encode the relevant CatchableType properties into the Flags bitfield.4253  // FIXME: Figure out how bits 2 or 8 can get set.4254  uint32_t Flags = 0;4255  if (IsScalar)4256    Flags |= 1;4257  if (HasVirtualBases)4258    Flags |= 4;4259  if (IsStdBadAlloc)4260    Flags |= 16;4261 4262  llvm::Constant *Fields[] = {4263      llvm::ConstantInt::get(CGM.IntTy, Flags),       // Flags4264      TD,                                             // TypeDescriptor4265      llvm::ConstantInt::get(CGM.IntTy, NVOffset),    // NonVirtualAdjustment4266      llvm::ConstantInt::get(CGM.IntTy, VBPtrOffset), // OffsetToVBPtr4267      llvm::ConstantInt::get(CGM.IntTy, VBIndex),     // VBTableIndex4268      llvm::ConstantInt::get(CGM.IntTy, Size),        // Size4269      CopyCtor                                        // CopyCtor4270  };4271  llvm::StructType *CTType = getCatchableTypeType();4272  auto *GV = new llvm::GlobalVariable(4273      CGM.getModule(), CTType, /*isConstant=*/true, getLinkageForRTTI(T),4274      llvm::ConstantStruct::get(CTType, Fields), MangledName);4275  GV->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);4276  GV->setSection(".xdata");4277  if (GV->isWeakForLinker())4278    GV->setComdat(CGM.getModule().getOrInsertComdat(GV->getName()));4279  return getImageRelativeConstant(GV);4280}4281 4282llvm::GlobalVariable *MicrosoftCXXABI::getCatchableTypeArray(QualType T) {4283  assert(!T->isReferenceType());4284 4285  // See if we've already generated a CatchableTypeArray for this type before.4286  llvm::GlobalVariable *&CTA = CatchableTypeArrays[T];4287  if (CTA)4288    return CTA;4289 4290  // Ensure that we don't have duplicate entries in our CatchableTypeArray by4291  // using a SmallSetVector.  Duplicates may arise due to virtual bases4292  // occurring more than once in the hierarchy.4293  llvm::SmallSetVector<llvm::Constant *, 2> CatchableTypes;4294 4295  // C++14 [except.handle]p3:4296  //   A handler is a match for an exception object of type E if [...]4297  //     - the handler is of type cv T or cv T& and T is an unambiguous public4298  //       base class of E, or4299  //     - the handler is of type cv T or const T& where T is a pointer type and4300  //       E is a pointer type that can be converted to T by [...]4301  //         - a standard pointer conversion (4.10) not involving conversions to4302  //           pointers to private or protected or ambiguous classes4303  const CXXRecordDecl *MostDerivedClass = nullptr;4304  bool IsPointer = T->isPointerType();4305  if (IsPointer)4306    MostDerivedClass = T->getPointeeType()->getAsCXXRecordDecl();4307  else4308    MostDerivedClass = T->getAsCXXRecordDecl();4309 4310  // Collect all the unambiguous public bases of the MostDerivedClass.4311  if (MostDerivedClass) {4312    const ASTContext &Context = getContext();4313    const ASTRecordLayout &MostDerivedLayout =4314        Context.getASTRecordLayout(MostDerivedClass);4315    MicrosoftVTableContext &VTableContext = CGM.getMicrosoftVTableContext();4316    SmallVector<MSRTTIClass, 8> Classes;4317    serializeClassHierarchy(Classes, MostDerivedClass);4318    Classes.front().initialize(/*Parent=*/nullptr, /*Specifier=*/nullptr);4319    detectAmbiguousBases(Classes);4320    for (const MSRTTIClass &Class : Classes) {4321      // Skip any ambiguous or private bases.4322      if (Class.Flags &4323          (MSRTTIClass::IsPrivateOnPath | MSRTTIClass::IsAmbiguous))4324        continue;4325      // Write down how to convert from a derived pointer to a base pointer.4326      uint32_t OffsetInVBTable = 0;4327      int32_t VBPtrOffset = -1;4328      if (Class.VirtualRoot) {4329        OffsetInVBTable =4330          VTableContext.getVBTableIndex(MostDerivedClass, Class.VirtualRoot)*4;4331        VBPtrOffset = MostDerivedLayout.getVBPtrOffset().getQuantity();4332      }4333 4334      // Turn our record back into a pointer if the exception object is a4335      // pointer.4336      CanQualType RTTITy = Context.getCanonicalTagType(Class.RD);4337      if (IsPointer)4338        RTTITy = Context.getPointerType(RTTITy);4339      CatchableTypes.insert(getCatchableType(RTTITy, Class.OffsetInVBase,4340                                             VBPtrOffset, OffsetInVBTable));4341    }4342  }4343 4344  // C++14 [except.handle]p3:4345  //   A handler is a match for an exception object of type E if4346  //     - The handler is of type cv T or cv T& and E and T are the same type4347  //       (ignoring the top-level cv-qualifiers)4348  CatchableTypes.insert(getCatchableType(T));4349 4350  // C++14 [except.handle]p3:4351  //   A handler is a match for an exception object of type E if4352  //     - the handler is of type cv T or const T& where T is a pointer type and4353  //       E is a pointer type that can be converted to T by [...]4354  //         - a standard pointer conversion (4.10) not involving conversions to4355  //           pointers to private or protected or ambiguous classes4356  //4357  // C++14 [conv.ptr]p2:4358  //   A prvalue of type "pointer to cv T," where T is an object type, can be4359  //   converted to a prvalue of type "pointer to cv void".4360  if (IsPointer && T->getPointeeType()->isObjectType())4361    CatchableTypes.insert(getCatchableType(getContext().VoidPtrTy));4362 4363  // C++14 [except.handle]p3:4364  //   A handler is a match for an exception object of type E if [...]4365  //     - the handler is of type cv T or const T& where T is a pointer or4366  //       pointer to member type and E is std::nullptr_t.4367  //4368  // We cannot possibly list all possible pointer types here, making this4369  // implementation incompatible with the standard.  However, MSVC includes an4370  // entry for pointer-to-void in this case.  Let's do the same.4371  if (T->isNullPtrType())4372    CatchableTypes.insert(getCatchableType(getContext().VoidPtrTy));4373 4374  uint32_t NumEntries = CatchableTypes.size();4375  llvm::Type *CTType = getImageRelativeType(CGM.DefaultPtrTy);4376  llvm::ArrayType *AT = llvm::ArrayType::get(CTType, NumEntries);4377  llvm::StructType *CTAType = getCatchableTypeArrayType(NumEntries);4378  llvm::Constant *Fields[] = {4379      llvm::ConstantInt::get(CGM.IntTy, NumEntries), // NumEntries4380      llvm::ConstantArray::get(4381          AT, llvm::ArrayRef(CatchableTypes.begin(),4382                             CatchableTypes.end())) // CatchableTypes4383  };4384  SmallString<256> MangledName;4385  {4386    llvm::raw_svector_ostream Out(MangledName);4387    getMangleContext().mangleCXXCatchableTypeArray(T, NumEntries, Out);4388  }4389  CTA = new llvm::GlobalVariable(4390      CGM.getModule(), CTAType, /*isConstant=*/true, getLinkageForRTTI(T),4391      llvm::ConstantStruct::get(CTAType, Fields), MangledName);4392  CTA->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);4393  CTA->setSection(".xdata");4394  if (CTA->isWeakForLinker())4395    CTA->setComdat(CGM.getModule().getOrInsertComdat(CTA->getName()));4396  return CTA;4397}4398 4399llvm::GlobalVariable *MicrosoftCXXABI::getThrowInfo(QualType T) {4400  bool IsConst, IsVolatile, IsUnaligned;4401  T = decomposeTypeForEH(getContext(), T, IsConst, IsVolatile, IsUnaligned);4402 4403  // The CatchableTypeArray enumerates the various (CV-unqualified) types that4404  // the exception object may be caught as.4405  llvm::GlobalVariable *CTA = getCatchableTypeArray(T);4406  // The first field in a CatchableTypeArray is the number of CatchableTypes.4407  // This is used as a component of the mangled name which means that we need to4408  // know what it is in order to see if we have previously generated the4409  // ThrowInfo.4410  uint32_t NumEntries =4411      cast<llvm::ConstantInt>(CTA->getInitializer()->getAggregateElement(0U))4412          ->getLimitedValue();4413 4414  SmallString<256> MangledName;4415  {4416    llvm::raw_svector_ostream Out(MangledName);4417    getMangleContext().mangleCXXThrowInfo(T, IsConst, IsVolatile, IsUnaligned,4418                                          NumEntries, Out);4419  }4420 4421  // Reuse a previously generated ThrowInfo if we have generated an appropriate4422  // one before.4423  if (llvm::GlobalVariable *GV = CGM.getModule().getNamedGlobal(MangledName))4424    return GV;4425 4426  // The RTTI TypeDescriptor uses an unqualified type but catch clauses must4427  // be at least as CV qualified.  Encode this requirement into the Flags4428  // bitfield.4429  uint32_t Flags = 0;4430  if (IsConst)4431    Flags |= 1;4432  if (IsVolatile)4433    Flags |= 2;4434  if (IsUnaligned)4435    Flags |= 4;4436 4437  // The cleanup-function (a destructor) must be called when the exception4438  // object's lifetime ends.4439  llvm::Constant *CleanupFn = llvm::Constant::getNullValue(CGM.Int8PtrTy);4440  if (const CXXRecordDecl *RD = T->getAsCXXRecordDecl())4441    if (CXXDestructorDecl *DtorD = RD->getDestructor())4442      if (!DtorD->isTrivial())4443        CleanupFn = CGM.getAddrOfCXXStructor(GlobalDecl(DtorD, Dtor_Complete));4444  // This is unused as far as we can tell, initialize it to null.4445  llvm::Constant *ForwardCompat =4446      getImageRelativeConstant(llvm::Constant::getNullValue(CGM.Int8PtrTy));4447  llvm::Constant *PointerToCatchableTypes = getImageRelativeConstant(CTA);4448  llvm::StructType *TIType = getThrowInfoType();4449  llvm::Constant *Fields[] = {4450      llvm::ConstantInt::get(CGM.IntTy, Flags), // Flags4451      getImageRelativeConstant(CleanupFn),      // CleanupFn4452      ForwardCompat,                            // ForwardCompat4453      PointerToCatchableTypes                   // CatchableTypeArray4454  };4455  auto *GV = new llvm::GlobalVariable(4456      CGM.getModule(), TIType, /*isConstant=*/true, getLinkageForRTTI(T),4457      llvm::ConstantStruct::get(TIType, Fields), MangledName.str());4458  GV->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);4459  GV->setSection(".xdata");4460  if (GV->isWeakForLinker())4461    GV->setComdat(CGM.getModule().getOrInsertComdat(GV->getName()));4462  return GV;4463}4464 4465void MicrosoftCXXABI::emitThrow(CodeGenFunction &CGF, const CXXThrowExpr *E) {4466  const Expr *SubExpr = E->getSubExpr();4467  assert(SubExpr && "SubExpr cannot be null");4468  QualType ThrowType = SubExpr->getType();4469  // The exception object lives on the stack and it's address is passed to the4470  // runtime function.4471  Address AI = CGF.CreateMemTemp(ThrowType);4472  CGF.EmitAnyExprToMem(SubExpr, AI, ThrowType.getQualifiers(),4473                       /*IsInit=*/true);4474 4475  // The so-called ThrowInfo is used to describe how the exception object may be4476  // caught.4477  llvm::GlobalVariable *TI = getThrowInfo(ThrowType);4478 4479  // Call into the runtime to throw the exception.4480  llvm::Value *Args[] = {AI.emitRawPointer(CGF), TI};4481  CGF.EmitNoreturnRuntimeCallOrInvoke(getThrowFn(), Args);4482}4483 4484std::pair<llvm::Value *, const CXXRecordDecl *>4485MicrosoftCXXABI::LoadVTablePtr(CodeGenFunction &CGF, Address This,4486                               const CXXRecordDecl *RD) {4487  CanQualType T = CGF.getContext().getCanonicalTagType(RD);4488  std::tie(This, std::ignore, RD) = performBaseAdjustment(CGF, This, T);4489  return {CGF.GetVTablePtr(This, CGM.Int8PtrTy, RD), RD};4490}4491 4492bool MicrosoftCXXABI::isPermittedToBeHomogeneousAggregate(4493    const CXXRecordDecl *RD) const {4494  // All aggregates are permitted to be HFA on non-ARM platforms, which mostly4495  // affects vectorcall on x64/x86.4496  if (!CGM.getTarget().getTriple().isAArch64())4497    return true;4498  // MSVC Windows on Arm64 has its own rules for determining if a type is HFA4499  // that are inconsistent with the AAPCS64 ABI. The following are our best4500  // determination of those rules so far, based on observation of MSVC's4501  // behavior.4502  if (RD->isEmpty())4503    return false;4504  if (RD->isPolymorphic())4505    return false;4506  if (RD->hasNonTrivialCopyAssignment())4507    return false;4508  if (RD->hasNonTrivialDestructor())4509    return false;4510  if (RD->hasNonTrivialDefaultConstructor())4511    return false;4512  // These two are somewhat redundant given the caller4513  // (ABIInfo::isHomogeneousAggregate) checks the bases and fields, but that4514  // caller doesn't consider empty bases/fields to be non-homogenous, but it4515  // looks like Microsoft's AArch64 ABI does care about these empty types &4516  // anything containing/derived from one is non-homogeneous.4517  // Instead we could add another CXXABI entry point to query this property and4518  // have ABIInfo::isHomogeneousAggregate use that property.4519  // I don't think any other of the features listed above could be true of a4520  // base/field while not true of the outer struct. For example, if you have a4521  // base/field that has an non-trivial copy assignment/dtor/default ctor, then4522  // the outer struct's corresponding operation must be non-trivial.4523  for (const CXXBaseSpecifier &B : RD->bases()) {4524    if (const CXXRecordDecl *FRD = B.getType()->getAsCXXRecordDecl()) {4525      if (!isPermittedToBeHomogeneousAggregate(FRD))4526        return false;4527    }4528  }4529  // empty fields seem to be caught by the ABIInfo::isHomogeneousAggregate4530  // checking for padding - but maybe there are ways to end up with an empty4531  // field without padding? Not that I know of, so don't check fields here &4532  // rely on the padding check.4533  return true;4534}4535