brintos / llvm-project-archived public Read only

1//===------- ItaniumCXXABI.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 Itanium C++ ABI.  The class10// in this file generates structures that follow the Itanium C++ ABI, which is11// documented at:12//  https://itanium-cxx-abi.github.io/cxx-abi/abi.html13//  https://itanium-cxx-abi.github.io/cxx-abi/abi-eh.html14//15// It also supports the closely-related ARM ABI, documented at:16// https://developer.arm.com/documentation/ihi0041/g/17//18//===----------------------------------------------------------------------===//19 20#include "CGCXXABI.h"21#include "CGCleanup.h"22#include "CGDebugInfo.h"23#include "CGRecordLayout.h"24#include "CGVTables.h"25#include "CodeGenFunction.h"26#include "CodeGenModule.h"27#include "TargetInfo.h"28#include "clang/AST/Attr.h"29#include "clang/AST/Mangle.h"30#include "clang/AST/StmtCXX.h"31#include "clang/AST/Type.h"32#include "clang/CodeGen/ConstantInitBuilder.h"33#include "llvm/IR/DataLayout.h"34#include "llvm/IR/GlobalValue.h"35#include "llvm/IR/Instructions.h"36#include "llvm/IR/Intrinsics.h"37#include "llvm/IR/Value.h"38#include "llvm/Support/ScopedPrinter.h"39 40#include <optional>41 42using namespace clang;43using namespace CodeGen;44 45namespace {46class ItaniumCXXABI : public CodeGen::CGCXXABI {47  /// VTables - All the vtables which have been defined.48  llvm::DenseMap<const CXXRecordDecl *, llvm::GlobalVariable *> VTables;49 50  /// All the thread wrapper functions that have been used.51  llvm::SmallVector<std::pair<const VarDecl *, llvm::Function *>, 8>52      ThreadWrappers;53 54protected:55  bool UseARMMethodPtrABI;56  bool UseARMGuardVarABI;57  bool Use32BitVTableOffsetABI;58 59  ItaniumMangleContext &getMangleContext() {60    return cast<ItaniumMangleContext>(CodeGen::CGCXXABI::getMangleContext());61  }62 63public:64  ItaniumCXXABI(CodeGen::CodeGenModule &CGM,65                bool UseARMMethodPtrABI = false,66                bool UseARMGuardVarABI = false) :67    CGCXXABI(CGM), UseARMMethodPtrABI(UseARMMethodPtrABI),68    UseARMGuardVarABI(UseARMGuardVarABI),69    Use32BitVTableOffsetABI(false) { }70 71  bool classifyReturnType(CGFunctionInfo &FI) const override;72 73  RecordArgABI getRecordArgABI(const CXXRecordDecl *RD) const override {74    // If C++ prohibits us from making a copy, pass by address.75    if (!RD->canPassInRegisters())76      return RAA_Indirect;77    return RAA_Default;78  }79 80  bool isThisCompleteObject(GlobalDecl GD) const override {81    // The Itanium ABI has separate complete-object vs.  base-object82    // variants of both constructors and destructors.83    if (isa<CXXDestructorDecl>(GD.getDecl())) {84      switch (GD.getDtorType()) {85      case Dtor_Complete:86      case Dtor_Deleting:87        return true;88 89      case Dtor_Base:90        return false;91 92      case Dtor_Comdat:93        llvm_unreachable("emitting dtor comdat as function?");94      case Dtor_Unified:95        llvm_unreachable("emitting unified dtor as function?");96      }97      llvm_unreachable("bad dtor kind");98    }99    if (isa<CXXConstructorDecl>(GD.getDecl())) {100      switch (GD.getCtorType()) {101      case Ctor_Complete:102        return true;103 104      case Ctor_Base:105        return false;106 107      case Ctor_CopyingClosure:108      case Ctor_DefaultClosure:109        llvm_unreachable("closure ctors in Itanium ABI?");110 111      case Ctor_Comdat:112        llvm_unreachable("emitting ctor comdat as function?");113 114      case Ctor_Unified:115        llvm_unreachable("emitting unified ctor as function?");116      }117      llvm_unreachable("bad dtor kind");118    }119 120    // No other kinds.121    return false;122  }123 124  bool isZeroInitializable(const MemberPointerType *MPT) override;125 126  llvm::Type *ConvertMemberPointerType(const MemberPointerType *MPT) override;127 128  CGCallee129    EmitLoadOfMemberFunctionPointer(CodeGenFunction &CGF,130                                    const Expr *E,131                                    Address This,132                                    llvm::Value *&ThisPtrForCall,133                                    llvm::Value *MemFnPtr,134                                    const MemberPointerType *MPT) override;135 136  llvm::Value *EmitMemberDataPointerAddress(CodeGenFunction &CGF, const Expr *E,137                                            Address Base, llvm::Value *MemPtr,138                                            const MemberPointerType *MPT,139                                            bool IsInBounds) override;140 141  llvm::Value *EmitMemberPointerConversion(CodeGenFunction &CGF,142                                           const CastExpr *E,143                                           llvm::Value *Src) override;144  llvm::Constant *EmitMemberPointerConversion(const CastExpr *E,145                                              llvm::Constant *Src) override;146 147  llvm::Constant *EmitNullMemberPointer(const MemberPointerType *MPT) override;148 149  llvm::Constant *EmitMemberFunctionPointer(const CXXMethodDecl *MD) override;150  llvm::Constant *EmitMemberDataPointer(const MemberPointerType *MPT,151                                        CharUnits offset) override;152  llvm::Constant *EmitMemberPointer(const APValue &MP, QualType MPT) override;153  llvm::Constant *BuildMemberPointer(const CXXMethodDecl *MD,154                                     CharUnits ThisAdjustment);155 156  llvm::Value *EmitMemberPointerComparison(CodeGenFunction &CGF,157                                           llvm::Value *L, llvm::Value *R,158                                           const MemberPointerType *MPT,159                                           bool Inequality) override;160 161  llvm::Value *EmitMemberPointerIsNotNull(CodeGenFunction &CGF,162                                         llvm::Value *Addr,163                                         const MemberPointerType *MPT) override;164 165  void emitVirtualObjectDelete(CodeGenFunction &CGF, const CXXDeleteExpr *DE,166                               Address Ptr, QualType ElementType,167                               const CXXDestructorDecl *Dtor) override;168 169  void emitRethrow(CodeGenFunction &CGF, bool isNoReturn) override;170  void emitThrow(CodeGenFunction &CGF, const CXXThrowExpr *E) override;171 172  void emitBeginCatch(CodeGenFunction &CGF, const CXXCatchStmt *C) override;173 174  llvm::CallInst *175  emitTerminateForUnexpectedException(CodeGenFunction &CGF,176                                      llvm::Value *Exn) override;177 178  void EmitFundamentalRTTIDescriptors(const CXXRecordDecl *RD);179  llvm::Constant *getAddrOfRTTIDescriptor(QualType Ty) override;180  CatchTypeInfo181  getAddrOfCXXCatchHandlerType(QualType Ty,182                               QualType CatchHandlerType) override {183    return CatchTypeInfo{getAddrOfRTTIDescriptor(Ty), 0};184  }185 186  bool shouldTypeidBeNullChecked(QualType SrcRecordTy) override;187  void EmitBadTypeidCall(CodeGenFunction &CGF) override;188  llvm::Value *EmitTypeid(CodeGenFunction &CGF, QualType SrcRecordTy,189                          Address ThisPtr,190                          llvm::Type *StdTypeInfoPtrTy) override;191 192  bool shouldDynamicCastCallBeNullChecked(bool SrcIsPtr,193                                          QualType SrcRecordTy) override;194 195  /// Determine whether we know that all instances of type RecordTy will have196  /// the same vtable pointer values, that is distinct from all other vtable197  /// pointers. While this is required by the Itanium ABI, it doesn't happen in198  /// practice in some cases due to language extensions.199  bool hasUniqueVTablePointer(QualType RecordTy) {200    const CXXRecordDecl *RD = RecordTy->getAsCXXRecordDecl();201 202    // Under -fapple-kext, multiple definitions of the same vtable may be203    // emitted.204    if (!CGM.getCodeGenOpts().AssumeUniqueVTables ||205        getContext().getLangOpts().AppleKext)206      return false;207 208    // If the type_info* would be null, the vtable might be merged with that of209    // another type.210    if (!CGM.shouldEmitRTTI())211      return false;212 213    // If there's only one definition of the vtable in the program, it has a214    // unique address.215    if (!llvm::GlobalValue::isWeakForLinker(CGM.getVTableLinkage(RD)))216      return true;217 218    // Even if there are multiple definitions of the vtable, they are required219    // by the ABI to use the same symbol name, so should be merged at load220    // time. However, if the class has hidden visibility, there can be221    // different versions of the class in different modules, and the ABI222    // library might treat them as being the same.223    if (CGM.GetLLVMVisibility(RD->getVisibility()) !=224        llvm::GlobalValue::DefaultVisibility)225      return false;226 227    return true;228  }229 230  bool shouldEmitExactDynamicCast(QualType DestRecordTy) override {231    return hasUniqueVTablePointer(DestRecordTy);232  }233 234  std::optional<ExactDynamicCastInfo>235  getExactDynamicCastInfo(QualType SrcRecordTy, QualType DestTy,236                          QualType DestRecordTy) override;237 238  llvm::Value *emitDynamicCastCall(CodeGenFunction &CGF, Address Value,239                                   QualType SrcRecordTy, QualType DestTy,240                                   QualType DestRecordTy,241                                   llvm::BasicBlock *CastEnd) override;242 243  llvm::Value *emitExactDynamicCast(CodeGenFunction &CGF, Address ThisAddr,244                                    QualType SrcRecordTy, QualType DestTy,245                                    QualType DestRecordTy,246                                    const ExactDynamicCastInfo &CastInfo,247                                    llvm::BasicBlock *CastSuccess,248                                    llvm::BasicBlock *CastFail) override;249 250  llvm::Value *emitDynamicCastToVoid(CodeGenFunction &CGF, Address Value,251                                     QualType SrcRecordTy) override;252 253  bool EmitBadCastCall(CodeGenFunction &CGF) override;254 255  llvm::Value *256    GetVirtualBaseClassOffset(CodeGenFunction &CGF, Address This,257                              const CXXRecordDecl *ClassDecl,258                              const CXXRecordDecl *BaseClassDecl) override;259 260  void EmitCXXConstructors(const CXXConstructorDecl *D) override;261 262  AddedStructorArgCounts263  buildStructorSignature(GlobalDecl GD,264                         SmallVectorImpl<CanQualType> &ArgTys) override;265 266  bool useThunkForDtorVariant(const CXXDestructorDecl *Dtor,267                              CXXDtorType DT) const override {268    // Itanium does not emit any destructor variant as an inline thunk.269    // Delegating may occur as an optimization, but all variants are either270    // emitted with external linkage or as linkonce if they are inline and used.271    return false;272  }273 274  void EmitCXXDestructors(const CXXDestructorDecl *D) override;275 276  void addImplicitStructorParams(CodeGenFunction &CGF, QualType &ResTy,277                                 FunctionArgList &Params) override;278 279  void EmitInstanceFunctionProlog(CodeGenFunction &CGF) override;280 281  AddedStructorArgs getImplicitConstructorArgs(CodeGenFunction &CGF,282                                               const CXXConstructorDecl *D,283                                               CXXCtorType Type,284                                               bool ForVirtualBase,285                                               bool Delegating) override;286 287  llvm::Value *getCXXDestructorImplicitParam(CodeGenFunction &CGF,288                                             const CXXDestructorDecl *DD,289                                             CXXDtorType Type,290                                             bool ForVirtualBase,291                                             bool Delegating) override;292 293  void EmitDestructorCall(CodeGenFunction &CGF, const CXXDestructorDecl *DD,294                          CXXDtorType Type, bool ForVirtualBase,295                          bool Delegating, Address This,296                          QualType ThisTy) override;297 298  void emitVTableDefinitions(CodeGenVTables &CGVT,299                             const CXXRecordDecl *RD) override;300 301  bool isVirtualOffsetNeededForVTableField(CodeGenFunction &CGF,302                                           CodeGenFunction::VPtr Vptr) override;303 304  bool doStructorsInitializeVPtrs(const CXXRecordDecl *VTableClass) override {305    return true;306  }307 308  llvm::Constant *309  getVTableAddressPoint(BaseSubobject Base,310                        const CXXRecordDecl *VTableClass) override;311 312  llvm::Value *getVTableAddressPointInStructor(313      CodeGenFunction &CGF, const CXXRecordDecl *VTableClass,314      BaseSubobject Base, const CXXRecordDecl *NearestVBase) override;315 316  llvm::Value *getVTableAddressPointInStructorWithVTT(317      CodeGenFunction &CGF, const CXXRecordDecl *VTableClass,318      BaseSubobject Base, const CXXRecordDecl *NearestVBase);319 320  llvm::GlobalVariable *getAddrOfVTable(const CXXRecordDecl *RD,321                                        CharUnits VPtrOffset) override;322 323  CGCallee getVirtualFunctionPointer(CodeGenFunction &CGF, GlobalDecl GD,324                                     Address This, llvm::Type *Ty,325                                     SourceLocation Loc) override;326 327  llvm::Value *328  EmitVirtualDestructorCall(CodeGenFunction &CGF, const CXXDestructorDecl *Dtor,329                            CXXDtorType DtorType, Address This,330                            DeleteOrMemberCallExpr E,331                            llvm::CallBase **CallOrInvoke) override;332 333  void emitVirtualInheritanceTables(const CXXRecordDecl *RD) override;334 335  bool canSpeculativelyEmitVTable(const CXXRecordDecl *RD) const override;336  bool canSpeculativelyEmitVTableAsBaseClass(const CXXRecordDecl *RD) const;337 338  void setThunkLinkage(llvm::Function *Thunk, bool ForVTable, GlobalDecl GD,339                       bool ReturnAdjustment) override {340    // Allow inlining of thunks by emitting them with available_externally341    // linkage together with vtables when needed.342    if (ForVTable && !Thunk->hasLocalLinkage())343      Thunk->setLinkage(llvm::GlobalValue::AvailableExternallyLinkage);344    CGM.setGVProperties(Thunk, GD);345  }346 347  bool exportThunk() override { return true; }348 349  llvm::Value *performThisAdjustment(CodeGenFunction &CGF, Address This,350                                     const CXXRecordDecl *UnadjustedThisClass,351                                     const ThunkInfo &TI) override;352 353  llvm::Value *performReturnAdjustment(CodeGenFunction &CGF, Address Ret,354                                       const CXXRecordDecl *UnadjustedRetClass,355                                       const ReturnAdjustment &RA) override;356 357  size_t getSrcArgforCopyCtor(const CXXConstructorDecl *,358                              FunctionArgList &Args) const override {359    assert(!Args.empty() && "expected the arglist to not be empty!");360    return Args.size() - 1;361  }362 363  StringRef GetPureVirtualCallName() override { return "__cxa_pure_virtual"; }364  StringRef GetDeletedVirtualCallName() override365    { return "__cxa_deleted_virtual"; }366 367  CharUnits getArrayCookieSizeImpl(QualType elementType) override;368  Address InitializeArrayCookie(CodeGenFunction &CGF,369                                Address NewPtr,370                                llvm::Value *NumElements,371                                const CXXNewExpr *expr,372                                QualType ElementType) override;373  llvm::Value *readArrayCookieImpl(CodeGenFunction &CGF,374                                   Address allocPtr,375                                   CharUnits cookieSize) override;376 377  void EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D,378                       llvm::GlobalVariable *DeclPtr,379                       bool PerformInit) override;380  void registerGlobalDtor(CodeGenFunction &CGF, const VarDecl &D,381                          llvm::FunctionCallee dtor,382                          llvm::Constant *addr) override;383 384  llvm::Function *getOrCreateThreadLocalWrapper(const VarDecl *VD,385                                                llvm::Value *Val);386  void EmitThreadLocalInitFuncs(387      CodeGenModule &CGM,388      ArrayRef<const VarDecl *> CXXThreadLocals,389      ArrayRef<llvm::Function *> CXXThreadLocalInits,390      ArrayRef<const VarDecl *> CXXThreadLocalInitVars) override;391 392  bool usesThreadWrapperFunction(const VarDecl *VD) const override {393    return !isEmittedWithConstantInitializer(VD) ||394           mayNeedDestruction(VD);395  }396  LValue EmitThreadLocalVarDeclLValue(CodeGenFunction &CGF, const VarDecl *VD,397                                      QualType LValType) override;398 399  bool NeedsVTTParameter(GlobalDecl GD) override;400 401  llvm::Constant *402  getOrCreateVirtualFunctionPointerThunk(const CXXMethodDecl *MD);403 404  /**************************** RTTI Uniqueness ******************************/405 406protected:407  /// Returns true if the ABI requires RTTI type_info objects to be unique408  /// across a program.409  virtual bool shouldRTTIBeUnique() const { return true; }410 411public:412  /// What sort of unique-RTTI behavior should we use?413  enum RTTIUniquenessKind {414    /// We are guaranteeing, or need to guarantee, that the RTTI string415    /// is unique.416    RUK_Unique,417 418    /// We are not guaranteeing uniqueness for the RTTI string, so we419    /// can demote to hidden visibility but must use string comparisons.420    RUK_NonUniqueHidden,421 422    /// We are not guaranteeing uniqueness for the RTTI string, so we423    /// have to use string comparisons, but we also have to emit it with424    /// non-hidden visibility.425    RUK_NonUniqueVisible426  };427 428  /// Return the required visibility status for the given type and linkage in429  /// the current ABI.430  RTTIUniquenessKind431  classifyRTTIUniqueness(QualType CanTy,432                         llvm::GlobalValue::LinkageTypes Linkage) const;433  friend class ItaniumRTTIBuilder;434 435  void emitCXXStructor(GlobalDecl GD) override;436 437  std::pair<llvm::Value *, const CXXRecordDecl *>438  LoadVTablePtr(CodeGenFunction &CGF, Address This,439                const CXXRecordDecl *RD) override;440 441 private:442   llvm::Constant *443   getSignedVirtualMemberFunctionPointer(const CXXMethodDecl *MD);444 445   bool hasAnyUnusedVirtualInlineFunction(const CXXRecordDecl *RD) const {446     const auto &VtableLayout =447         CGM.getItaniumVTableContext().getVTableLayout(RD);448 449     for (const auto &VtableComponent : VtableLayout.vtable_components()) {450       // Skip empty slot.451       if (!VtableComponent.isUsedFunctionPointerKind())452         continue;453 454       const CXXMethodDecl *Method = VtableComponent.getFunctionDecl();455       const FunctionDecl *FD = Method->getDefinition();456       const bool IsInlined =457           Method->getCanonicalDecl()->isInlined() || (FD && FD->isInlined());458       if (!IsInlined)459         continue;460 461       StringRef Name = CGM.getMangledName(VtableComponent.getGlobalDecl());462       auto *Entry = CGM.GetGlobalValue(Name);463       // This checks if virtual inline function has already been emitted.464       // Note that it is possible that this inline function would be emitted465       // after trying to emit vtable speculatively. Because of this we do466       // an extra pass after emitting all deferred vtables to find and emit467       // these vtables opportunistically.468       if (!Entry || Entry->isDeclaration())469         return true;470     }471     return false;472  }473 474  bool isVTableHidden(const CXXRecordDecl *RD) const {475    const auto &VtableLayout =476            CGM.getItaniumVTableContext().getVTableLayout(RD);477 478    for (const auto &VtableComponent : VtableLayout.vtable_components()) {479      if (VtableComponent.isRTTIKind()) {480        const CXXRecordDecl *RTTIDecl = VtableComponent.getRTTIDecl();481        if (RTTIDecl->getVisibility() == Visibility::HiddenVisibility)482          return true;483      } else if (VtableComponent.isUsedFunctionPointerKind()) {484        const CXXMethodDecl *Method = VtableComponent.getFunctionDecl();485        if (Method->getVisibility() == Visibility::HiddenVisibility &&486            !Method->isDefined())487          return true;488      }489    }490    return false;491  }492};493 494class ARMCXXABI : public ItaniumCXXABI {495public:496  ARMCXXABI(CodeGen::CodeGenModule &CGM) :497    ItaniumCXXABI(CGM, /*UseARMMethodPtrABI=*/true,498                  /*UseARMGuardVarABI=*/true) {}499 500  bool constructorsAndDestructorsReturnThis() const override { return true; }501 502  void EmitReturnFromThunk(CodeGenFunction &CGF, RValue RV,503                           QualType ResTy) override;504 505  CharUnits getArrayCookieSizeImpl(QualType elementType) override;506  Address InitializeArrayCookie(CodeGenFunction &CGF,507                                Address NewPtr,508                                llvm::Value *NumElements,509                                const CXXNewExpr *expr,510                                QualType ElementType) override;511  llvm::Value *readArrayCookieImpl(CodeGenFunction &CGF, Address allocPtr,512                                   CharUnits cookieSize) override;513};514 515class AppleARM64CXXABI : public ARMCXXABI {516public:517  AppleARM64CXXABI(CodeGen::CodeGenModule &CGM) : ARMCXXABI(CGM) {518    Use32BitVTableOffsetABI = true;519  }520 521  // ARM64 libraries are prepared for non-unique RTTI.522  bool shouldRTTIBeUnique() const override { return false; }523};524 525class FuchsiaCXXABI final : public ItaniumCXXABI {526public:527  explicit FuchsiaCXXABI(CodeGen::CodeGenModule &CGM)528      : ItaniumCXXABI(CGM) {}529 530private:531  bool constructorsAndDestructorsReturnThis() const override { return true; }532};533 534class WebAssemblyCXXABI final : public ItaniumCXXABI {535public:536  explicit WebAssemblyCXXABI(CodeGen::CodeGenModule &CGM)537      : ItaniumCXXABI(CGM, /*UseARMMethodPtrABI=*/true,538                      /*UseARMGuardVarABI=*/true) {}539  void emitBeginCatch(CodeGenFunction &CGF, const CXXCatchStmt *C) override;540  llvm::CallInst *541  emitTerminateForUnexpectedException(CodeGenFunction &CGF,542                                      llvm::Value *Exn) override;543 544private:545  bool constructorsAndDestructorsReturnThis() const override { return true; }546  bool canCallMismatchedFunctionType() const override { return false; }547};548 549class XLCXXABI final : public ItaniumCXXABI {550public:551  explicit XLCXXABI(CodeGen::CodeGenModule &CGM)552      : ItaniumCXXABI(CGM) {}553 554  void registerGlobalDtor(CodeGenFunction &CGF, const VarDecl &D,555                          llvm::FunctionCallee dtor,556                          llvm::Constant *addr) override;557 558  bool useSinitAndSterm() const override { return true; }559 560private:561  void emitCXXStermFinalizer(const VarDecl &D, llvm::Function *dtorStub,562                             llvm::Constant *addr);563};564}565 566CodeGen::CGCXXABI *CodeGen::CreateItaniumCXXABI(CodeGenModule &CGM) {567  switch (CGM.getContext().getCXXABIKind()) {568  // For IR-generation purposes, there's no significant difference569  // between the ARM and iOS ABIs.570  case TargetCXXABI::GenericARM:571  case TargetCXXABI::iOS:572  case TargetCXXABI::WatchOS:573    return new ARMCXXABI(CGM);574 575  case TargetCXXABI::AppleARM64:576    return new AppleARM64CXXABI(CGM);577 578  case TargetCXXABI::Fuchsia:579    return new FuchsiaCXXABI(CGM);580 581  // Note that AArch64 uses the generic ItaniumCXXABI class since it doesn't582  // include the other 32-bit ARM oddities: constructor/destructor return values583  // and array cookies.584  case TargetCXXABI::GenericAArch64:585    return new ItaniumCXXABI(CGM, /*UseARMMethodPtrABI=*/true,586                             /*UseARMGuardVarABI=*/true);587 588  case TargetCXXABI::GenericMIPS:589    return new ItaniumCXXABI(CGM, /*UseARMMethodPtrABI=*/true);590 591  case TargetCXXABI::WebAssembly:592    return new WebAssemblyCXXABI(CGM);593 594  case TargetCXXABI::XL:595    return new XLCXXABI(CGM);596 597  case TargetCXXABI::GenericItanium:598    return new ItaniumCXXABI(CGM);599 600  case TargetCXXABI::Microsoft:601    llvm_unreachable("Microsoft ABI is not Itanium-based");602  }603  llvm_unreachable("bad ABI kind");604}605 606llvm::Type *607ItaniumCXXABI::ConvertMemberPointerType(const MemberPointerType *MPT) {608  if (MPT->isMemberDataPointer())609    return CGM.PtrDiffTy;610  return llvm::StructType::get(CGM.PtrDiffTy, CGM.PtrDiffTy);611}612 613/// In the Itanium and ARM ABIs, method pointers have the form:614///   struct { ptrdiff_t ptr; ptrdiff_t adj; } memptr;615///616/// In the Itanium ABI:617///  - method pointers are virtual if (memptr.ptr & 1) is nonzero618///  - the this-adjustment is (memptr.adj)619///  - the virtual offset is (memptr.ptr - 1)620///621/// In the ARM ABI:622///  - method pointers are virtual if (memptr.adj & 1) is nonzero623///  - the this-adjustment is (memptr.adj >> 1)624///  - the virtual offset is (memptr.ptr)625/// ARM uses 'adj' for the virtual flag because Thumb functions626/// may be only single-byte aligned.627///628/// If the member is virtual, the adjusted 'this' pointer points629/// to a vtable pointer from which the virtual offset is applied.630///631/// If the member is non-virtual, memptr.ptr is the address of632/// the function to call.633CGCallee ItaniumCXXABI::EmitLoadOfMemberFunctionPointer(634    CodeGenFunction &CGF, const Expr *E, Address ThisAddr,635    llvm::Value *&ThisPtrForCall,636    llvm::Value *MemFnPtr, const MemberPointerType *MPT) {637  CGBuilderTy &Builder = CGF.Builder;638 639  const FunctionProtoType *FPT =640      MPT->getPointeeType()->castAs<FunctionProtoType>();641  auto *RD = MPT->getMostRecentCXXRecordDecl();642 643  llvm::Constant *ptrdiff_1 = llvm::ConstantInt::get(CGM.PtrDiffTy, 1);644 645  llvm::BasicBlock *FnVirtual = CGF.createBasicBlock("memptr.virtual");646  llvm::BasicBlock *FnNonVirtual = CGF.createBasicBlock("memptr.nonvirtual");647  llvm::BasicBlock *FnEnd = CGF.createBasicBlock("memptr.end");648 649  // Extract memptr.adj, which is in the second field.650  llvm::Value *RawAdj = Builder.CreateExtractValue(MemFnPtr, 1, "memptr.adj");651 652  // Compute the true adjustment.653  llvm::Value *Adj = RawAdj;654  if (UseARMMethodPtrABI)655    Adj = Builder.CreateAShr(Adj, ptrdiff_1, "memptr.adj.shifted");656 657  // Apply the adjustment and cast back to the original struct type658  // for consistency.659  llvm::Value *This = ThisAddr.emitRawPointer(CGF);660  This = Builder.CreateInBoundsGEP(Builder.getInt8Ty(), This, Adj);661  ThisPtrForCall = This;662 663  // Load the function pointer.664  llvm::Value *FnAsInt = Builder.CreateExtractValue(MemFnPtr, 0, "memptr.ptr");665 666  // If the LSB in the function pointer is 1, the function pointer points to667  // a virtual function.668  llvm::Value *IsVirtual;669  if (UseARMMethodPtrABI)670    IsVirtual = Builder.CreateAnd(RawAdj, ptrdiff_1);671  else672    IsVirtual = Builder.CreateAnd(FnAsInt, ptrdiff_1);673  IsVirtual = Builder.CreateIsNotNull(IsVirtual, "memptr.isvirtual");674  Builder.CreateCondBr(IsVirtual, FnVirtual, FnNonVirtual);675 676  // In the virtual path, the adjustment left 'This' pointing to the677  // vtable of the correct base subobject.  The "function pointer" is an678  // offset within the vtable (+1 for the virtual flag on non-ARM).679  CGF.EmitBlock(FnVirtual);680 681  // Cast the adjusted this to a pointer to vtable pointer and load.682  llvm::Type *VTableTy = CGF.CGM.GlobalsInt8PtrTy;683  CharUnits VTablePtrAlign =684    CGF.CGM.getDynamicOffsetAlignment(ThisAddr.getAlignment(), RD,685                                      CGF.getPointerAlign());686  llvm::Value *VTable = CGF.GetVTablePtr(687      Address(This, ThisAddr.getElementType(), VTablePtrAlign), VTableTy, RD);688 689  // Apply the offset.690  // On ARM64, to reserve extra space in virtual member function pointers,691  // we only pay attention to the low 32 bits of the offset.692  llvm::Value *VTableOffset = FnAsInt;693  if (!UseARMMethodPtrABI)694    VTableOffset = Builder.CreateSub(VTableOffset, ptrdiff_1);695  if (Use32BitVTableOffsetABI) {696    VTableOffset = Builder.CreateTrunc(VTableOffset, CGF.Int32Ty);697    VTableOffset = Builder.CreateZExt(VTableOffset, CGM.PtrDiffTy);698  }699 700  // Check the address of the function pointer if CFI on member function701  // pointers is enabled.702  llvm::Constant *CheckSourceLocation;703  llvm::Constant *CheckTypeDesc;704  bool ShouldEmitCFICheck = CGF.SanOpts.has(SanitizerKind::CFIMFCall) &&705                            CGM.HasHiddenLTOVisibility(RD);706 707  if (ShouldEmitCFICheck) {708    if (const auto *BinOp = dyn_cast<BinaryOperator>(E)) {709      if (BinOp->isPtrMemOp() &&710          BinOp->getRHS()711              ->getType()712              ->hasPointeeToToCFIUncheckedCalleeFunctionType())713        ShouldEmitCFICheck = false;714    }715  }716 717  bool ShouldEmitVFEInfo = CGM.getCodeGenOpts().VirtualFunctionElimination &&718                           CGM.HasHiddenLTOVisibility(RD);719  bool ShouldEmitWPDInfo =720      CGM.getCodeGenOpts().WholeProgramVTables &&721      // Don't insert type tests if we are forcing public visibility.722      !CGM.AlwaysHasLTOVisibilityPublic(RD);723  llvm::Value *VirtualFn = nullptr;724 725  {726    auto CheckOrdinal = SanitizerKind::SO_CFIMFCall;727    auto CheckHandler = SanitizerHandler::CFICheckFail;728    SanitizerDebugLocation SanScope(&CGF, {CheckOrdinal}, CheckHandler);729 730    llvm::Value *TypeId = nullptr;731    llvm::Value *CheckResult = nullptr;732 733    if (ShouldEmitCFICheck || ShouldEmitVFEInfo || ShouldEmitWPDInfo) {734      // If doing CFI, VFE or WPD, we will need the metadata node to check735      // against.736      llvm::Metadata *MD =737          CGM.CreateMetadataIdentifierForVirtualMemPtrType(QualType(MPT, 0));738      TypeId = llvm::MetadataAsValue::get(CGF.getLLVMContext(), MD);739    }740 741    if (ShouldEmitVFEInfo) {742      llvm::Value *VFPAddr =743          Builder.CreateGEP(CGF.Int8Ty, VTable, VTableOffset);744 745      // If doing VFE, load from the vtable with a type.checked.load intrinsic746      // call. Note that we use the GEP to calculate the address to load from747      // and pass 0 as the offset to the intrinsic. This is because every748      // vtable slot of the correct type is marked with matching metadata, and749      // we know that the load must be from one of these slots.750      llvm::Value *CheckedLoad = Builder.CreateCall(751          CGM.getIntrinsic(llvm::Intrinsic::type_checked_load),752          {VFPAddr, llvm::ConstantInt::get(CGM.Int32Ty, 0), TypeId});753      CheckResult = Builder.CreateExtractValue(CheckedLoad, 1);754      VirtualFn = Builder.CreateExtractValue(CheckedLoad, 0);755    } else {756      // When not doing VFE, emit a normal load, as it allows more757      // optimisations than type.checked.load.758      if (ShouldEmitCFICheck || ShouldEmitWPDInfo) {759        llvm::Value *VFPAddr =760            Builder.CreateGEP(CGF.Int8Ty, VTable, VTableOffset);761        llvm::Intrinsic::ID IID = CGM.HasHiddenLTOVisibility(RD)762                                      ? llvm::Intrinsic::type_test763                                      : llvm::Intrinsic::public_type_test;764 765        CheckResult =766            Builder.CreateCall(CGM.getIntrinsic(IID), {VFPAddr, TypeId});767      }768 769      if (CGM.getItaniumVTableContext().isRelativeLayout()) {770        VirtualFn = CGF.Builder.CreateCall(771            CGM.getIntrinsic(llvm::Intrinsic::load_relative,772                             {VTableOffset->getType()}),773            {VTable, VTableOffset});774      } else {775        llvm::Value *VFPAddr =776            CGF.Builder.CreateGEP(CGF.Int8Ty, VTable, VTableOffset);777        VirtualFn = CGF.Builder.CreateAlignedLoad(CGF.DefaultPtrTy, VFPAddr,778                                                  CGF.getPointerAlign(),779                                                  "memptr.virtualfn");780      }781    }782    assert(VirtualFn && "Virtual fuction pointer not created!");783    assert((!ShouldEmitCFICheck || !ShouldEmitVFEInfo || !ShouldEmitWPDInfo ||784            CheckResult) &&785           "Check result required but not created!");786 787    if (ShouldEmitCFICheck) {788      // If doing CFI, emit the check.789      CheckSourceLocation = CGF.EmitCheckSourceLocation(E->getBeginLoc());790      CheckTypeDesc = CGF.EmitCheckTypeDescriptor(QualType(MPT, 0));791      llvm::Constant *StaticData[] = {792          llvm::ConstantInt::get(CGF.Int8Ty, CodeGenFunction::CFITCK_VMFCall),793          CheckSourceLocation,794          CheckTypeDesc,795      };796 797      if (CGM.getCodeGenOpts().SanitizeTrap.has(SanitizerKind::CFIMFCall)) {798        CGF.EmitTrapCheck(CheckResult, CheckHandler);799      } else {800        llvm::Value *AllVtables = llvm::MetadataAsValue::get(801            CGM.getLLVMContext(),802            llvm::MDString::get(CGM.getLLVMContext(), "all-vtables"));803        llvm::Value *ValidVtable = Builder.CreateCall(804            CGM.getIntrinsic(llvm::Intrinsic::type_test), {VTable, AllVtables});805        CGF.EmitCheck(std::make_pair(CheckResult, CheckOrdinal), CheckHandler,806                      StaticData, {VTable, ValidVtable});807      }808 809      FnVirtual = Builder.GetInsertBlock();810    }811  } // End of sanitizer scope812 813  CGF.EmitBranch(FnEnd);814 815  // In the non-virtual path, the function pointer is actually a816  // function pointer.817  CGF.EmitBlock(FnNonVirtual);818  llvm::Value *NonVirtualFn =819      Builder.CreateIntToPtr(FnAsInt, CGF.DefaultPtrTy, "memptr.nonvirtualfn");820 821  // Check the function pointer if CFI on member function pointers is enabled.822  if (ShouldEmitCFICheck) {823    CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl();824    if (RD->hasDefinition()) {825      auto CheckOrdinal = SanitizerKind::SO_CFIMFCall;826      auto CheckHandler = SanitizerHandler::CFICheckFail;827      SanitizerDebugLocation SanScope(&CGF, {CheckOrdinal}, CheckHandler);828 829      llvm::Constant *StaticData[] = {830          llvm::ConstantInt::get(CGF.Int8Ty, CodeGenFunction::CFITCK_NVMFCall),831          CheckSourceLocation,832          CheckTypeDesc,833      };834 835      llvm::Value *Bit = Builder.getFalse();836      for (const CXXRecordDecl *Base : CGM.getMostBaseClasses(RD)) {837        llvm::Metadata *MD = CGM.CreateMetadataIdentifierForType(838            getContext().getMemberPointerType(MPT->getPointeeType(),839                                              /*Qualifier=*/std::nullopt,840                                              Base->getCanonicalDecl()));841        llvm::Value *TypeId =842            llvm::MetadataAsValue::get(CGF.getLLVMContext(), MD);843 844        llvm::Value *TypeTest =845            Builder.CreateCall(CGM.getIntrinsic(llvm::Intrinsic::type_test),846                               {NonVirtualFn, TypeId});847        Bit = Builder.CreateOr(Bit, TypeTest);848      }849 850      CGF.EmitCheck(std::make_pair(Bit, CheckOrdinal), CheckHandler, StaticData,851                    {NonVirtualFn, llvm::UndefValue::get(CGF.IntPtrTy)});852 853      FnNonVirtual = Builder.GetInsertBlock();854    }855  }856 857  // We're done.858  CGF.EmitBlock(FnEnd);859  llvm::PHINode *CalleePtr = Builder.CreatePHI(CGF.DefaultPtrTy, 2);860  CalleePtr->addIncoming(VirtualFn, FnVirtual);861  CalleePtr->addIncoming(NonVirtualFn, FnNonVirtual);862 863  CGPointerAuthInfo PointerAuth;864 865  if (const auto &Schema =866          CGM.getCodeGenOpts().PointerAuth.CXXMemberFunctionPointers) {867    llvm::PHINode *DiscriminatorPHI = Builder.CreatePHI(CGF.IntPtrTy, 2);868    DiscriminatorPHI->addIncoming(llvm::ConstantInt::get(CGF.IntPtrTy, 0),869                                  FnVirtual);870    const auto &AuthInfo =871        CGM.getMemberFunctionPointerAuthInfo(QualType(MPT, 0));872    assert(Schema.getKey() == AuthInfo.getKey() &&873           "Keys for virtual and non-virtual member functions must match");874    auto *NonVirtualDiscriminator = AuthInfo.getDiscriminator();875    DiscriminatorPHI->addIncoming(NonVirtualDiscriminator, FnNonVirtual);876    PointerAuth = CGPointerAuthInfo(877        Schema.getKey(), Schema.getAuthenticationMode(), Schema.isIsaPointer(),878        Schema.authenticatesNullValues(), DiscriminatorPHI);879  }880 881  CGCallee Callee(FPT, CalleePtr, PointerAuth);882  return Callee;883}884 885/// Compute an l-value by applying the given pointer-to-member to a886/// base object.887llvm::Value *ItaniumCXXABI::EmitMemberDataPointerAddress(888    CodeGenFunction &CGF, const Expr *E, Address Base, llvm::Value *MemPtr,889    const MemberPointerType *MPT, bool IsInBounds) {890  assert(MemPtr->getType() == CGM.PtrDiffTy);891 892  CGBuilderTy &Builder = CGF.Builder;893 894  // Apply the offset.895  llvm::Value *BaseAddr = Base.emitRawPointer(CGF);896  return Builder.CreateGEP(CGF.Int8Ty, BaseAddr, MemPtr, "memptr.offset",897                           IsInBounds ? llvm::GEPNoWrapFlags::inBounds()898                                      : llvm::GEPNoWrapFlags::none());899}900 901// See if it's possible to return a constant signed pointer.902static llvm::Constant *pointerAuthResignConstant(903    llvm::Value *Ptr, const CGPointerAuthInfo &CurAuthInfo,904    const CGPointerAuthInfo &NewAuthInfo, CodeGenModule &CGM) {905  const auto *CPA = dyn_cast<llvm::ConstantPtrAuth>(Ptr);906 907  if (!CPA)908    return nullptr;909 910  assert(CPA->getKey()->getZExtValue() == CurAuthInfo.getKey() &&911         CPA->getAddrDiscriminator()->isZeroValue() &&912         CPA->getDiscriminator() == CurAuthInfo.getDiscriminator() &&913         "unexpected key or discriminators");914 915  return CGM.getConstantSignedPointer(916      CPA->getPointer(), NewAuthInfo.getKey(), nullptr,917      cast<llvm::ConstantInt>(NewAuthInfo.getDiscriminator()));918}919 920/// Perform a bitcast, derived-to-base, or base-to-derived member pointer921/// conversion.922///923/// Bitcast conversions are always a no-op under Itanium.924///925/// Obligatory offset/adjustment diagram:926///         <-- offset -->          <-- adjustment -->927///   |--------------------------|----------------------|--------------------|928///   ^Derived address point     ^Base address point    ^Member address point929///930/// So when converting a base member pointer to a derived member pointer,931/// we add the offset to the adjustment because the address point has932/// decreased;  and conversely, when converting a derived MP to a base MP933/// we subtract the offset from the adjustment because the address point934/// has increased.935///936/// The standard forbids (at compile time) conversion to and from937/// virtual bases, which is why we don't have to consider them here.938///939/// The standard forbids (at run time) casting a derived MP to a base940/// MP when the derived MP does not point to a member of the base.941/// This is why -1 is a reasonable choice for null data member942/// pointers.943llvm::Value *944ItaniumCXXABI::EmitMemberPointerConversion(CodeGenFunction &CGF,945                                           const CastExpr *E,946                                           llvm::Value *src) {947  // Use constant emission if we can.948  if (isa<llvm::Constant>(src))949    return EmitMemberPointerConversion(E, cast<llvm::Constant>(src));950 951  assert(E->getCastKind() == CK_DerivedToBaseMemberPointer ||952         E->getCastKind() == CK_BaseToDerivedMemberPointer ||953         E->getCastKind() == CK_ReinterpretMemberPointer);954 955  CGBuilderTy &Builder = CGF.Builder;956  QualType DstType = E->getType();957 958  if (DstType->isMemberFunctionPointerType()) {959    if (const auto &NewAuthInfo =960            CGM.getMemberFunctionPointerAuthInfo(DstType)) {961      QualType SrcType = E->getSubExpr()->getType();962      assert(SrcType->isMemberFunctionPointerType());963      const auto &CurAuthInfo = CGM.getMemberFunctionPointerAuthInfo(SrcType);964      llvm::Value *MemFnPtr = Builder.CreateExtractValue(src, 0, "memptr.ptr");965      llvm::Type *OrigTy = MemFnPtr->getType();966 967      llvm::BasicBlock *StartBB = Builder.GetInsertBlock();968      llvm::BasicBlock *ResignBB = CGF.createBasicBlock("resign");969      llvm::BasicBlock *MergeBB = CGF.createBasicBlock("merge");970 971      // Check whether we have a virtual offset or a pointer to a function.972      assert(UseARMMethodPtrABI && "ARM ABI expected");973      llvm::Value *Adj = Builder.CreateExtractValue(src, 1, "memptr.adj");974      llvm::Constant *Ptrdiff_1 = llvm::ConstantInt::get(CGM.PtrDiffTy, 1);975      llvm::Value *AndVal = Builder.CreateAnd(Adj, Ptrdiff_1);976      llvm::Value *IsVirtualOffset =977          Builder.CreateIsNotNull(AndVal, "is.virtual.offset");978      Builder.CreateCondBr(IsVirtualOffset, MergeBB, ResignBB);979 980      CGF.EmitBlock(ResignBB);981      llvm::Type *PtrTy = llvm::PointerType::getUnqual(CGM.getLLVMContext());982      MemFnPtr = Builder.CreateIntToPtr(MemFnPtr, PtrTy);983      MemFnPtr =984          CGF.emitPointerAuthResign(MemFnPtr, SrcType, CurAuthInfo, NewAuthInfo,985                                    isa<llvm::Constant>(src));986      MemFnPtr = Builder.CreatePtrToInt(MemFnPtr, OrigTy);987      llvm::Value *ResignedVal = Builder.CreateInsertValue(src, MemFnPtr, 0);988      ResignBB = Builder.GetInsertBlock();989 990      CGF.EmitBlock(MergeBB);991      llvm::PHINode *NewSrc = Builder.CreatePHI(src->getType(), 2);992      NewSrc->addIncoming(src, StartBB);993      NewSrc->addIncoming(ResignedVal, ResignBB);994      src = NewSrc;995    }996  }997 998  // Under Itanium, reinterprets don't require any additional processing.999  if (E->getCastKind() == CK_ReinterpretMemberPointer) return src;1000 1001  llvm::Constant *adj = getMemberPointerAdjustment(E);1002  if (!adj) return src;1003 1004  bool isDerivedToBase = (E->getCastKind() == CK_DerivedToBaseMemberPointer);1005 1006  const MemberPointerType *destTy =1007    E->getType()->castAs<MemberPointerType>();1008 1009  // For member data pointers, this is just a matter of adding the1010  // offset if the source is non-null.1011  if (destTy->isMemberDataPointer()) {1012    llvm::Value *dst;1013    if (isDerivedToBase)1014      dst = Builder.CreateNSWSub(src, adj, "adj");1015    else1016      dst = Builder.CreateNSWAdd(src, adj, "adj");1017 1018    // Null check.1019    llvm::Value *null = llvm::Constant::getAllOnesValue(src->getType());1020    llvm::Value *isNull = Builder.CreateICmpEQ(src, null, "memptr.isnull");1021    return Builder.CreateSelect(isNull, src, dst);1022  }1023 1024  // The this-adjustment is left-shifted by 1 on ARM.1025  if (UseARMMethodPtrABI) {1026    uint64_t offset = cast<llvm::ConstantInt>(adj)->getZExtValue();1027    offset <<= 1;1028    adj = llvm::ConstantInt::get(adj->getType(), offset);1029  }1030 1031  llvm::Value *srcAdj = Builder.CreateExtractValue(src, 1, "src.adj");1032  llvm::Value *dstAdj;1033  if (isDerivedToBase)1034    dstAdj = Builder.CreateNSWSub(srcAdj, adj, "adj");1035  else1036    dstAdj = Builder.CreateNSWAdd(srcAdj, adj, "adj");1037 1038  return Builder.CreateInsertValue(src, dstAdj, 1);1039}1040 1041static llvm::Constant *1042pointerAuthResignMemberFunctionPointer(llvm::Constant *Src, QualType DestType,1043                                       QualType SrcType, CodeGenModule &CGM) {1044  assert(DestType->isMemberFunctionPointerType() &&1045         SrcType->isMemberFunctionPointerType() &&1046         "member function pointers expected");1047  if (DestType == SrcType)1048    return Src;1049 1050  const auto &NewAuthInfo = CGM.getMemberFunctionPointerAuthInfo(DestType);1051  const auto &CurAuthInfo = CGM.getMemberFunctionPointerAuthInfo(SrcType);1052 1053  if (!NewAuthInfo && !CurAuthInfo)1054    return Src;1055 1056  llvm::Constant *MemFnPtr = Src->getAggregateElement(0u);1057  if (MemFnPtr->getNumOperands() == 0) {1058    // src must be a pair of null pointers.1059    assert(isa<llvm::ConstantInt>(MemFnPtr) && "constant int expected");1060    return Src;1061  }1062 1063  llvm::Constant *ConstPtr = pointerAuthResignConstant(1064      cast<llvm::User>(MemFnPtr)->getOperand(0), CurAuthInfo, NewAuthInfo, CGM);1065  ConstPtr = llvm::ConstantExpr::getPtrToInt(ConstPtr, MemFnPtr->getType());1066  return ConstantFoldInsertValueInstruction(Src, ConstPtr, 0);1067}1068 1069llvm::Constant *1070ItaniumCXXABI::EmitMemberPointerConversion(const CastExpr *E,1071                                           llvm::Constant *src) {1072  assert(E->getCastKind() == CK_DerivedToBaseMemberPointer ||1073         E->getCastKind() == CK_BaseToDerivedMemberPointer ||1074         E->getCastKind() == CK_ReinterpretMemberPointer);1075 1076  QualType DstType = E->getType();1077 1078  if (DstType->isMemberFunctionPointerType())1079    src = pointerAuthResignMemberFunctionPointer(1080        src, DstType, E->getSubExpr()->getType(), CGM);1081 1082  // Under Itanium, reinterprets don't require any additional processing.1083  if (E->getCastKind() == CK_ReinterpretMemberPointer) return src;1084 1085  // If the adjustment is trivial, we don't need to do anything.1086  llvm::Constant *adj = getMemberPointerAdjustment(E);1087  if (!adj) return src;1088 1089  bool isDerivedToBase = (E->getCastKind() == CK_DerivedToBaseMemberPointer);1090 1091  const MemberPointerType *destTy =1092    E->getType()->castAs<MemberPointerType>();1093 1094  // For member data pointers, this is just a matter of adding the1095  // offset if the source is non-null.1096  if (destTy->isMemberDataPointer()) {1097    // null maps to null.1098    if (src->isAllOnesValue()) return src;1099 1100    if (isDerivedToBase)1101      return llvm::ConstantExpr::getNSWSub(src, adj);1102    else1103      return llvm::ConstantExpr::getNSWAdd(src, adj);1104  }1105 1106  // The this-adjustment is left-shifted by 1 on ARM.1107  if (UseARMMethodPtrABI) {1108    uint64_t offset = cast<llvm::ConstantInt>(adj)->getZExtValue();1109    offset <<= 1;1110    adj = llvm::ConstantInt::get(adj->getType(), offset);1111  }1112 1113  llvm::Constant *srcAdj = src->getAggregateElement(1);1114  llvm::Constant *dstAdj;1115  if (isDerivedToBase)1116    dstAdj = llvm::ConstantExpr::getNSWSub(srcAdj, adj);1117  else1118    dstAdj = llvm::ConstantExpr::getNSWAdd(srcAdj, adj);1119 1120  llvm::Constant *res = ConstantFoldInsertValueInstruction(src, dstAdj, 1);1121  assert(res != nullptr && "Folding must succeed");1122  return res;1123}1124 1125llvm::Constant *1126ItaniumCXXABI::EmitNullMemberPointer(const MemberPointerType *MPT) {1127  // Itanium C++ ABI 2.3:1128  //   A NULL pointer is represented as -1.1129  if (MPT->isMemberDataPointer())1130    return llvm::ConstantInt::get(CGM.PtrDiffTy, -1ULL, /*isSigned=*/true);1131 1132  llvm::Constant *Zero = llvm::ConstantInt::get(CGM.PtrDiffTy, 0);1133  llvm::Constant *Values[2] = { Zero, Zero };1134  return llvm::ConstantStruct::getAnon(Values);1135}1136 1137llvm::Constant *1138ItaniumCXXABI::EmitMemberDataPointer(const MemberPointerType *MPT,1139                                     CharUnits offset) {1140  // Itanium C++ ABI 2.3:1141  //   A pointer to data member is an offset from the base address of1142  //   the class object containing it, represented as a ptrdiff_t1143  return llvm::ConstantInt::get(CGM.PtrDiffTy, offset.getQuantity());1144}1145 1146llvm::Constant *1147ItaniumCXXABI::EmitMemberFunctionPointer(const CXXMethodDecl *MD) {1148  return BuildMemberPointer(MD, CharUnits::Zero());1149}1150 1151llvm::Constant *ItaniumCXXABI::BuildMemberPointer(const CXXMethodDecl *MD,1152                                                  CharUnits ThisAdjustment) {1153  assert(MD->isInstance() && "Member function must not be static!");1154 1155  CodeGenTypes &Types = CGM.getTypes();1156 1157  // Get the function pointer (or index if this is a virtual function).1158  llvm::Constant *MemPtr[2];1159  if (MD->isVirtual()) {1160    uint64_t Index = CGM.getItaniumVTableContext().getMethodVTableIndex(MD);1161    uint64_t VTableOffset;1162    if (CGM.getItaniumVTableContext().isRelativeLayout()) {1163      // Multiply by 4-byte relative offsets.1164      VTableOffset = Index * 4;1165    } else {1166      const ASTContext &Context = getContext();1167      CharUnits PointerWidth = Context.toCharUnitsFromBits(1168          Context.getTargetInfo().getPointerWidth(LangAS::Default));1169      VTableOffset = Index * PointerWidth.getQuantity();1170    }1171 1172    if (UseARMMethodPtrABI) {1173      // ARM C++ ABI 3.2.1:1174      //   This ABI specifies that adj contains twice the this1175      //   adjustment, plus 1 if the member function is virtual. The1176      //   least significant bit of adj then makes exactly the same1177      //   discrimination as the least significant bit of ptr does for1178      //   Itanium.1179 1180      // We cannot use the Itanium ABI's representation for virtual member1181      // function pointers under pointer authentication because it would1182      // require us to store both the virtual offset and the constant1183      // discriminator in the pointer, which would be immediately vulnerable1184      // to attack.  Instead we introduce a thunk that does the virtual dispatch1185      // and store it as if it were a non-virtual member function.  This means1186      // that virtual function pointers may not compare equal anymore, but1187      // fortunately they aren't required to by the standard, and we do make1188      // a best-effort attempt to re-use the thunk.1189      //1190      // To support interoperation with code in which pointer authentication1191      // is disabled, derefencing a member function pointer must still handle1192      // the virtual case, but it can use a discriminator which should never1193      // be valid.1194      const auto &Schema =1195          CGM.getCodeGenOpts().PointerAuth.CXXMemberFunctionPointers;1196      if (Schema)1197        MemPtr[0] = llvm::ConstantExpr::getPtrToInt(1198            getSignedVirtualMemberFunctionPointer(MD), CGM.PtrDiffTy);1199      else1200        MemPtr[0] = llvm::ConstantInt::get(CGM.PtrDiffTy, VTableOffset);1201      // Don't set the LSB of adj to 1 if pointer authentication for member1202      // function pointers is enabled.1203      MemPtr[1] = llvm::ConstantInt::get(1204          CGM.PtrDiffTy, 2 * ThisAdjustment.getQuantity() + !Schema);1205    } else {1206      // Itanium C++ ABI 2.3:1207      //   For a virtual function, [the pointer field] is 1 plus the1208      //   virtual table offset (in bytes) of the function,1209      //   represented as a ptrdiff_t.1210      MemPtr[0] = llvm::ConstantInt::get(CGM.PtrDiffTy, VTableOffset + 1);1211      MemPtr[1] = llvm::ConstantInt::get(CGM.PtrDiffTy,1212                                         ThisAdjustment.getQuantity());1213    }1214  } else {1215    const FunctionProtoType *FPT = MD->getType()->castAs<FunctionProtoType>();1216    llvm::Type *Ty;1217    // Check whether the function has a computable LLVM signature.1218    if (Types.isFuncTypeConvertible(FPT)) {1219      // The function has a computable LLVM signature; use the correct type.1220      Ty = Types.GetFunctionType(Types.arrangeCXXMethodDeclaration(MD));1221    } else {1222      // Use an arbitrary non-function type to tell GetAddrOfFunction that the1223      // function type is incomplete.1224      Ty = CGM.PtrDiffTy;1225    }1226    llvm::Constant *addr = CGM.getMemberFunctionPointer(MD, Ty);1227 1228    MemPtr[0] = llvm::ConstantExpr::getPtrToInt(addr, CGM.PtrDiffTy);1229    MemPtr[1] = llvm::ConstantInt::get(CGM.PtrDiffTy,1230                                       (UseARMMethodPtrABI ? 2 : 1) *1231                                       ThisAdjustment.getQuantity());1232  }1233 1234  return llvm::ConstantStruct::getAnon(MemPtr);1235}1236 1237llvm::Constant *ItaniumCXXABI::EmitMemberPointer(const APValue &MP,1238                                                 QualType MPType) {1239  const MemberPointerType *MPT = MPType->castAs<MemberPointerType>();1240  const ValueDecl *MPD = MP.getMemberPointerDecl();1241  if (!MPD)1242    return EmitNullMemberPointer(MPT);1243 1244  CharUnits ThisAdjustment = getContext().getMemberPointerPathAdjustment(MP);1245 1246  if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(MPD)) {1247    llvm::Constant *Src = BuildMemberPointer(MD, ThisAdjustment);1248    QualType SrcType = getContext().getMemberPointerType(1249        MD->getType(), /*Qualifier=*/std::nullopt, MD->getParent());1250    return pointerAuthResignMemberFunctionPointer(Src, MPType, SrcType, CGM);1251  }1252 1253  CharUnits FieldOffset =1254    getContext().toCharUnitsFromBits(getContext().getFieldOffset(MPD));1255  return EmitMemberDataPointer(MPT, ThisAdjustment + FieldOffset);1256}1257 1258/// The comparison algorithm is pretty easy: the member pointers are1259/// the same if they're either bitwise identical *or* both null.1260///1261/// ARM is different here only because null-ness is more complicated.1262llvm::Value *1263ItaniumCXXABI::EmitMemberPointerComparison(CodeGenFunction &CGF,1264                                           llvm::Value *L,1265                                           llvm::Value *R,1266                                           const MemberPointerType *MPT,1267                                           bool Inequality) {1268  CGBuilderTy &Builder = CGF.Builder;1269 1270  llvm::ICmpInst::Predicate Eq;1271  llvm::Instruction::BinaryOps And, Or;1272  if (Inequality) {1273    Eq = llvm::ICmpInst::ICMP_NE;1274    And = llvm::Instruction::Or;1275    Or = llvm::Instruction::And;1276  } else {1277    Eq = llvm::ICmpInst::ICMP_EQ;1278    And = llvm::Instruction::And;1279    Or = llvm::Instruction::Or;1280  }1281 1282  // Member data pointers are easy because there's a unique null1283  // value, so it just comes down to bitwise equality.1284  if (MPT->isMemberDataPointer())1285    return Builder.CreateICmp(Eq, L, R);1286 1287  // For member function pointers, the tautologies are more complex.1288  // The Itanium tautology is:1289  //   (L == R) <==> (L.ptr == R.ptr && (L.ptr == 0 || L.adj == R.adj))1290  // The ARM tautology is:1291  //   (L == R) <==> (L.ptr == R.ptr &&1292  //                  (L.adj == R.adj ||1293  //                   (L.ptr == 0 && ((L.adj|R.adj) & 1) == 0)))1294  // The inequality tautologies have exactly the same structure, except1295  // applying De Morgan's laws.1296 1297  llvm::Value *LPtr = Builder.CreateExtractValue(L, 0, "lhs.memptr.ptr");1298  llvm::Value *RPtr = Builder.CreateExtractValue(R, 0, "rhs.memptr.ptr");1299 1300  // This condition tests whether L.ptr == R.ptr.  This must always be1301  // true for equality to hold.1302  llvm::Value *PtrEq = Builder.CreateICmp(Eq, LPtr, RPtr, "cmp.ptr");1303 1304  // This condition, together with the assumption that L.ptr == R.ptr,1305  // tests whether the pointers are both null.  ARM imposes an extra1306  // condition.1307  llvm::Value *Zero = llvm::Constant::getNullValue(LPtr->getType());1308  llvm::Value *EqZero = Builder.CreateICmp(Eq, LPtr, Zero, "cmp.ptr.null");1309 1310  // This condition tests whether L.adj == R.adj.  If this isn't1311  // true, the pointers are unequal unless they're both null.1312  llvm::Value *LAdj = Builder.CreateExtractValue(L, 1, "lhs.memptr.adj");1313  llvm::Value *RAdj = Builder.CreateExtractValue(R, 1, "rhs.memptr.adj");1314  llvm::Value *AdjEq = Builder.CreateICmp(Eq, LAdj, RAdj, "cmp.adj");1315 1316  // Null member function pointers on ARM clear the low bit of Adj,1317  // so the zero condition has to check that neither low bit is set.1318  if (UseARMMethodPtrABI) {1319    llvm::Value *One = llvm::ConstantInt::get(LPtr->getType(), 1);1320 1321    // Compute (l.adj | r.adj) & 1 and test it against zero.1322    llvm::Value *OrAdj = Builder.CreateOr(LAdj, RAdj, "or.adj");1323    llvm::Value *OrAdjAnd1 = Builder.CreateAnd(OrAdj, One);1324    llvm::Value *OrAdjAnd1EqZero = Builder.CreateICmp(Eq, OrAdjAnd1, Zero,1325                                                      "cmp.or.adj");1326    EqZero = Builder.CreateBinOp(And, EqZero, OrAdjAnd1EqZero);1327  }1328 1329  // Tie together all our conditions.1330  llvm::Value *Result = Builder.CreateBinOp(Or, EqZero, AdjEq);1331  Result = Builder.CreateBinOp(And, PtrEq, Result,1332                               Inequality ? "memptr.ne" : "memptr.eq");1333  return Result;1334}1335 1336llvm::Value *1337ItaniumCXXABI::EmitMemberPointerIsNotNull(CodeGenFunction &CGF,1338                                          llvm::Value *MemPtr,1339                                          const MemberPointerType *MPT) {1340  CGBuilderTy &Builder = CGF.Builder;1341 1342  /// For member data pointers, this is just a check against -1.1343  if (MPT->isMemberDataPointer()) {1344    assert(MemPtr->getType() == CGM.PtrDiffTy);1345    llvm::Value *NegativeOne =1346      llvm::Constant::getAllOnesValue(MemPtr->getType());1347    return Builder.CreateICmpNE(MemPtr, NegativeOne, "memptr.tobool");1348  }1349 1350  // In Itanium, a member function pointer is not null if 'ptr' is not null.1351  llvm::Value *Ptr = Builder.CreateExtractValue(MemPtr, 0, "memptr.ptr");1352 1353  llvm::Constant *Zero = llvm::ConstantInt::get(Ptr->getType(), 0);1354  llvm::Value *Result = Builder.CreateICmpNE(Ptr, Zero, "memptr.tobool");1355 1356  // On ARM, a member function pointer is also non-null if the low bit of 'adj'1357  // (the virtual bit) is set.1358  if (UseARMMethodPtrABI) {1359    llvm::Constant *One = llvm::ConstantInt::get(Ptr->getType(), 1);1360    llvm::Value *Adj = Builder.CreateExtractValue(MemPtr, 1, "memptr.adj");1361    llvm::Value *VirtualBit = Builder.CreateAnd(Adj, One, "memptr.virtualbit");1362    llvm::Value *IsVirtual = Builder.CreateICmpNE(VirtualBit, Zero,1363                                                  "memptr.isvirtual");1364    Result = Builder.CreateOr(Result, IsVirtual);1365  }1366 1367  return Result;1368}1369 1370bool ItaniumCXXABI::classifyReturnType(CGFunctionInfo &FI) const {1371  const CXXRecordDecl *RD = FI.getReturnType()->getAsCXXRecordDecl();1372  if (!RD)1373    return false;1374 1375  // If C++ prohibits us from making a copy, return by address.1376  if (!RD->canPassInRegisters()) {1377    auto Align = CGM.getContext().getTypeAlignInChars(FI.getReturnType());1378    FI.getReturnInfo() = ABIArgInfo::getIndirect(1379        Align, /*AddrSpace=*/CGM.getDataLayout().getAllocaAddrSpace(),1380        /*ByVal=*/false);1381    return true;1382  }1383  return false;1384}1385 1386/// The Itanium ABI requires non-zero initialization only for data1387/// member pointers, for which '0' is a valid offset.1388bool ItaniumCXXABI::isZeroInitializable(const MemberPointerType *MPT) {1389  return MPT->isMemberFunctionPointer();1390}1391 1392/// The Itanium ABI always places an offset to the complete object1393/// at entry -2 in the vtable.1394void ItaniumCXXABI::emitVirtualObjectDelete(CodeGenFunction &CGF,1395                                            const CXXDeleteExpr *DE,1396                                            Address Ptr,1397                                            QualType ElementType,1398                                            const CXXDestructorDecl *Dtor) {1399  bool UseGlobalDelete = DE->isGlobalDelete();1400  if (UseGlobalDelete) {1401    // Derive the complete-object pointer, which is what we need1402    // to pass to the deallocation function.1403 1404    // Grab the vtable pointer as an intptr_t*.1405    auto *ClassDecl = ElementType->castAsCXXRecordDecl();1406    llvm::Value *VTable = CGF.GetVTablePtr(Ptr, CGF.DefaultPtrTy, ClassDecl);1407 1408    // Track back to entry -2 and pull out the offset there.1409    llvm::Value *OffsetPtr = CGF.Builder.CreateConstInBoundsGEP1_64(1410        CGF.IntPtrTy, VTable, -2, "complete-offset.ptr");1411    llvm::Value *Offset = CGF.Builder.CreateAlignedLoad(CGF.IntPtrTy, OffsetPtr,1412                                                        CGF.getPointerAlign());1413 1414    // Apply the offset.1415    llvm::Value *CompletePtr = Ptr.emitRawPointer(CGF);1416    CompletePtr =1417        CGF.Builder.CreateInBoundsGEP(CGF.Int8Ty, CompletePtr, Offset);1418 1419    // If we're supposed to call the global delete, make sure we do so1420    // even if the destructor throws.1421    CGF.pushCallObjectDeleteCleanup(DE->getOperatorDelete(), CompletePtr,1422                                    ElementType);1423  }1424 1425  // FIXME: Provide a source location here even though there's no1426  // CXXMemberCallExpr for dtor call.1427  CXXDtorType DtorType = UseGlobalDelete ? Dtor_Complete : Dtor_Deleting;1428  EmitVirtualDestructorCall(CGF, Dtor, DtorType, Ptr, DE,1429                            /*CallOrInvoke=*/nullptr);1430 1431  if (UseGlobalDelete)1432    CGF.PopCleanupBlock();1433}1434 1435void ItaniumCXXABI::emitRethrow(CodeGenFunction &CGF, bool isNoReturn) {1436  // void __cxa_rethrow();1437 1438  llvm::FunctionType *FTy =1439    llvm::FunctionType::get(CGM.VoidTy, /*isVarArg=*/false);1440 1441  llvm::FunctionCallee Fn = CGM.CreateRuntimeFunction(FTy, "__cxa_rethrow");1442 1443  if (isNoReturn)1444    CGF.EmitNoreturnRuntimeCallOrInvoke(Fn, {});1445  else1446    CGF.EmitRuntimeCallOrInvoke(Fn);1447}1448 1449static llvm::FunctionCallee getAllocateExceptionFn(CodeGenModule &CGM) {1450  // void *__cxa_allocate_exception(size_t thrown_size);1451 1452  llvm::FunctionType *FTy =1453    llvm::FunctionType::get(CGM.Int8PtrTy, CGM.SizeTy, /*isVarArg=*/false);1454 1455  return CGM.CreateRuntimeFunction(FTy, "__cxa_allocate_exception");1456}1457 1458static llvm::FunctionCallee getThrowFn(CodeGenModule &CGM) {1459  // void __cxa_throw(void *thrown_exception, std::type_info *tinfo,1460  //                  void (*dest) (void *));1461 1462  llvm::Type *Args[3] = { CGM.Int8PtrTy, CGM.GlobalsInt8PtrTy, CGM.Int8PtrTy };1463  llvm::FunctionType *FTy =1464    llvm::FunctionType::get(CGM.VoidTy, Args, /*isVarArg=*/false);1465 1466  return CGM.CreateRuntimeFunction(FTy, "__cxa_throw");1467}1468 1469void ItaniumCXXABI::emitThrow(CodeGenFunction &CGF, const CXXThrowExpr *E) {1470  QualType ThrowType = E->getSubExpr()->getType();1471  // Now allocate the exception object.1472  llvm::Type *SizeTy = CGF.ConvertType(getContext().getSizeType());1473  uint64_t TypeSize = getContext().getTypeSizeInChars(ThrowType).getQuantity();1474 1475  llvm::FunctionCallee AllocExceptionFn = getAllocateExceptionFn(CGM);1476  llvm::CallInst *ExceptionPtr = CGF.EmitNounwindRuntimeCall(1477      AllocExceptionFn, llvm::ConstantInt::get(SizeTy, TypeSize), "exception");1478 1479  CharUnits ExnAlign = CGF.getContext().getExnObjectAlignment();1480  CGF.EmitAnyExprToExn(1481      E->getSubExpr(), Address(ExceptionPtr, CGM.Int8Ty, ExnAlign));1482 1483  // Now throw the exception.1484  llvm::Constant *TypeInfo = CGM.GetAddrOfRTTIDescriptor(ThrowType,1485                                                         /*ForEH=*/true);1486 1487  // The address of the destructor.  If the exception type has a1488  // trivial destructor (or isn't a record), we just pass null.1489  llvm::Constant *Dtor = nullptr;1490  if (const auto *Record = ThrowType->getAsCXXRecordDecl();1491      Record && !Record->hasTrivialDestructor()) {1492    // __cxa_throw is declared to take its destructor as void (*)(void *). We1493    // must match that if function pointers can be authenticated with a1494    // discriminator based on their type.1495    const ASTContext &Ctx = getContext();1496    QualType DtorTy = Ctx.getFunctionType(Ctx.VoidTy, {Ctx.VoidPtrTy},1497                                          FunctionProtoType::ExtProtoInfo());1498 1499    CXXDestructorDecl *DtorD = Record->getDestructor();1500    Dtor = CGM.getAddrOfCXXStructor(GlobalDecl(DtorD, Dtor_Complete));1501    Dtor = CGM.getFunctionPointer(Dtor, DtorTy);1502  }1503  if (!Dtor) Dtor = llvm::Constant::getNullValue(CGM.Int8PtrTy);1504 1505  llvm::Value *args[] = { ExceptionPtr, TypeInfo, Dtor };1506  CGF.EmitNoreturnRuntimeCallOrInvoke(getThrowFn(CGM), args);1507}1508 1509static llvm::FunctionCallee getItaniumDynamicCastFn(CodeGenFunction &CGF) {1510  // void *__dynamic_cast(const void *sub,1511  //                      global_as const abi::__class_type_info *src,1512  //                      global_as const abi::__class_type_info *dst,1513  //                      std::ptrdiff_t src2dst_offset);1514 1515  llvm::Type *Int8PtrTy = CGF.Int8PtrTy;1516  llvm::Type *GlobInt8PtrTy = CGF.GlobalsInt8PtrTy;1517  llvm::Type *PtrDiffTy =1518    CGF.ConvertType(CGF.getContext().getPointerDiffType());1519 1520  llvm::Type *Args[4] = { Int8PtrTy, GlobInt8PtrTy, GlobInt8PtrTy, PtrDiffTy };1521 1522  llvm::FunctionType *FTy = llvm::FunctionType::get(Int8PtrTy, Args, false);1523 1524  // Mark the function as nounwind willreturn readonly.1525  llvm::AttrBuilder FuncAttrs(CGF.getLLVMContext());1526  FuncAttrs.addAttribute(llvm::Attribute::NoUnwind);1527  FuncAttrs.addAttribute(llvm::Attribute::WillReturn);1528  FuncAttrs.addMemoryAttr(llvm::MemoryEffects::readOnly());1529  llvm::AttributeList Attrs = llvm::AttributeList::get(1530      CGF.getLLVMContext(), llvm::AttributeList::FunctionIndex, FuncAttrs);1531 1532  return CGF.CGM.CreateRuntimeFunction(FTy, "__dynamic_cast", Attrs);1533}1534 1535static llvm::FunctionCallee getBadCastFn(CodeGenFunction &CGF) {1536  // void __cxa_bad_cast();1537  llvm::FunctionType *FTy = llvm::FunctionType::get(CGF.VoidTy, false);1538  return CGF.CGM.CreateRuntimeFunction(FTy, "__cxa_bad_cast");1539}1540 1541/// Compute the src2dst_offset hint as described in the1542/// Itanium C++ ABI [2.9.7]1543static CharUnits computeOffsetHint(ASTContext &Context,1544                                   const CXXRecordDecl *Src,1545                                   const CXXRecordDecl *Dst) {1546  CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true,1547                     /*DetectVirtual=*/false);1548 1549  // If Dst is not derived from Src we can skip the whole computation below and1550  // return that Src is not a public base of Dst.  Record all inheritance paths.1551  if (!Dst->isDerivedFrom(Src, Paths))1552    return CharUnits::fromQuantity(-2ULL);1553 1554  unsigned NumPublicPaths = 0;1555  CharUnits Offset;1556 1557  // Now walk all possible inheritance paths.1558  for (const CXXBasePath &Path : Paths) {1559    if (Path.Access != AS_public)  // Ignore non-public inheritance.1560      continue;1561 1562    ++NumPublicPaths;1563 1564    for (const CXXBasePathElement &PathElement : Path) {1565      // If the path contains a virtual base class we can't give any hint.1566      // -1: no hint.1567      if (PathElement.Base->isVirtual())1568        return CharUnits::fromQuantity(-1ULL);1569 1570      if (NumPublicPaths > 1) // Won't use offsets, skip computation.1571        continue;1572 1573      // Accumulate the base class offsets.1574      const ASTRecordLayout &L = Context.getASTRecordLayout(PathElement.Class);1575      Offset += L.getBaseClassOffset(1576          PathElement.Base->getType()->getAsCXXRecordDecl());1577    }1578  }1579 1580  // -2: Src is not a public base of Dst.1581  if (NumPublicPaths == 0)1582    return CharUnits::fromQuantity(-2ULL);1583 1584  // -3: Src is a multiple public base type but never a virtual base type.1585  if (NumPublicPaths > 1)1586    return CharUnits::fromQuantity(-3ULL);1587 1588  // Otherwise, the Src type is a unique public nonvirtual base type of Dst.1589  // Return the offset of Src from the origin of Dst.1590  return Offset;1591}1592 1593static llvm::FunctionCallee getBadTypeidFn(CodeGenFunction &CGF) {1594  // void __cxa_bad_typeid();1595  llvm::FunctionType *FTy = llvm::FunctionType::get(CGF.VoidTy, false);1596 1597  return CGF.CGM.CreateRuntimeFunction(FTy, "__cxa_bad_typeid");1598}1599 1600bool ItaniumCXXABI::shouldTypeidBeNullChecked(QualType SrcRecordTy) {1601  return true;1602}1603 1604void ItaniumCXXABI::EmitBadTypeidCall(CodeGenFunction &CGF) {1605  llvm::FunctionCallee Fn = getBadTypeidFn(CGF);1606  llvm::CallBase *Call = CGF.EmitRuntimeCallOrInvoke(Fn);1607  Call->setDoesNotReturn();1608  CGF.Builder.CreateUnreachable();1609}1610 1611llvm::Value *ItaniumCXXABI::EmitTypeid(CodeGenFunction &CGF,1612                                       QualType SrcRecordTy,1613                                       Address ThisPtr,1614                                       llvm::Type *StdTypeInfoPtrTy) {1615  auto *ClassDecl = SrcRecordTy->castAsCXXRecordDecl();1616  llvm::Value *Value = CGF.GetVTablePtr(ThisPtr, CGM.GlobalsInt8PtrTy,1617                                        ClassDecl);1618 1619  if (CGM.getItaniumVTableContext().isRelativeLayout()) {1620    // Load the type info.1621    Value = CGF.Builder.CreateCall(1622        CGM.getIntrinsic(llvm::Intrinsic::load_relative, {CGM.Int32Ty}),1623        {Value, llvm::ConstantInt::get(CGM.Int32Ty, -4)});1624  } else {1625    // Load the type info.1626    Value =1627        CGF.Builder.CreateConstInBoundsGEP1_64(StdTypeInfoPtrTy, Value, -1ULL);1628  }1629  return CGF.Builder.CreateAlignedLoad(StdTypeInfoPtrTy, Value,1630                                       CGF.getPointerAlign());1631}1632 1633bool ItaniumCXXABI::shouldDynamicCastCallBeNullChecked(bool SrcIsPtr,1634                                                       QualType SrcRecordTy) {1635  return SrcIsPtr;1636}1637 1638llvm::Value *ItaniumCXXABI::emitDynamicCastCall(1639    CodeGenFunction &CGF, Address ThisAddr, QualType SrcRecordTy,1640    QualType DestTy, QualType DestRecordTy, llvm::BasicBlock *CastEnd) {1641  llvm::Type *PtrDiffLTy =1642      CGF.ConvertType(CGF.getContext().getPointerDiffType());1643 1644  llvm::Value *SrcRTTI =1645      CGF.CGM.GetAddrOfRTTIDescriptor(SrcRecordTy.getUnqualifiedType());1646  llvm::Value *DestRTTI =1647      CGF.CGM.GetAddrOfRTTIDescriptor(DestRecordTy.getUnqualifiedType());1648 1649  // Compute the offset hint.1650  const CXXRecordDecl *SrcDecl = SrcRecordTy->getAsCXXRecordDecl();1651  const CXXRecordDecl *DestDecl = DestRecordTy->getAsCXXRecordDecl();1652  llvm::Value *OffsetHint = llvm::ConstantInt::get(1653      PtrDiffLTy,1654      computeOffsetHint(CGF.getContext(), SrcDecl, DestDecl).getQuantity());1655 1656  // Emit the call to __dynamic_cast.1657  llvm::Value *Value = ThisAddr.emitRawPointer(CGF);1658  if (CGM.getCodeGenOpts().PointerAuth.CXXVTablePointers) {1659    // We perform a no-op load of the vtable pointer here to force an1660    // authentication. In environments that do not support pointer1661    // authentication this is a an actual no-op that will be elided. When1662    // pointer authentication is supported and enforced on vtable pointers this1663    // load can trap.1664    llvm::Value *Vtable =1665        CGF.GetVTablePtr(ThisAddr, CGM.Int8PtrTy, SrcDecl,1666                         CodeGenFunction::VTableAuthMode::MustTrap);1667    assert(Vtable);1668    (void)Vtable;1669  }1670 1671  llvm::Value *args[] = {Value, SrcRTTI, DestRTTI, OffsetHint};1672  Value = CGF.EmitNounwindRuntimeCall(getItaniumDynamicCastFn(CGF), args);1673 1674  /// C++ [expr.dynamic.cast]p9:1675  ///   A failed cast to reference type throws std::bad_cast1676  if (DestTy->isReferenceType()) {1677    llvm::BasicBlock *BadCastBlock =1678        CGF.createBasicBlock("dynamic_cast.bad_cast");1679 1680    llvm::Value *IsNull = CGF.Builder.CreateIsNull(Value);1681    CGF.Builder.CreateCondBr(IsNull, BadCastBlock, CastEnd);1682 1683    CGF.EmitBlock(BadCastBlock);1684    EmitBadCastCall(CGF);1685  }1686 1687  return Value;1688}1689 1690std::optional<CGCXXABI::ExactDynamicCastInfo>1691ItaniumCXXABI::getExactDynamicCastInfo(QualType SrcRecordTy, QualType DestTy,1692                                       QualType DestRecordTy) {1693  assert(shouldEmitExactDynamicCast(DestRecordTy));1694 1695  ASTContext &Context = getContext();1696 1697  // Find all the inheritance paths.1698  const CXXRecordDecl *SrcDecl = SrcRecordTy->getAsCXXRecordDecl();1699  const CXXRecordDecl *DestDecl = DestRecordTy->getAsCXXRecordDecl();1700  CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true,1701                     /*DetectVirtual=*/false);1702  (void)DestDecl->isDerivedFrom(SrcDecl, Paths);1703 1704  // Find an offset within `DestDecl` where a `SrcDecl` instance and its vptr1705  // might appear.1706  std::optional<CharUnits> Offset;1707  for (const CXXBasePath &Path : Paths) {1708    // dynamic_cast only finds public inheritance paths.1709    if (Path.Access != AS_public)1710      continue;1711 1712    CharUnits PathOffset;1713    for (const CXXBasePathElement &PathElement : Path) {1714      // Find the offset along this inheritance step.1715      const CXXRecordDecl *Base =1716          PathElement.Base->getType()->getAsCXXRecordDecl();1717      if (PathElement.Base->isVirtual()) {1718        // For a virtual base class, we know that the derived class is exactly1719        // DestDecl, so we can use the vbase offset from its layout.1720        const ASTRecordLayout &L = Context.getASTRecordLayout(DestDecl);1721        PathOffset = L.getVBaseClassOffset(Base);1722      } else {1723        const ASTRecordLayout &L =1724            Context.getASTRecordLayout(PathElement.Class);1725        PathOffset += L.getBaseClassOffset(Base);1726      }1727    }1728 1729    if (!Offset)1730      Offset = PathOffset;1731    else if (Offset != PathOffset) {1732      // Base appears in at least two different places.1733      return ExactDynamicCastInfo{/*RequiresCastToPrimaryBase=*/true,1734                                  CharUnits::Zero()};1735    }1736  }1737  if (!Offset)1738    return std::nullopt;1739  return ExactDynamicCastInfo{/*RequiresCastToPrimaryBase=*/false, *Offset};1740}1741 1742llvm::Value *ItaniumCXXABI::emitExactDynamicCast(1743    CodeGenFunction &CGF, Address ThisAddr, QualType SrcRecordTy,1744    QualType DestTy, QualType DestRecordTy,1745    const ExactDynamicCastInfo &ExactCastInfo, llvm::BasicBlock *CastSuccess,1746    llvm::BasicBlock *CastFail) {1747  const CXXRecordDecl *SrcDecl = SrcRecordTy->getAsCXXRecordDecl();1748  const CXXRecordDecl *DestDecl = DestRecordTy->getAsCXXRecordDecl();1749  auto AuthenticateVTable = [&](Address ThisAddr, const CXXRecordDecl *Decl) {1750    if (!CGF.getLangOpts().PointerAuthCalls)1751      return;1752    (void)CGF.GetVTablePtr(ThisAddr, CGF.DefaultPtrTy, Decl,1753                           CodeGenFunction::VTableAuthMode::MustTrap);1754  };1755 1756  bool PerformPostCastAuthentication = false;1757  llvm::Value *VTable = nullptr;1758  if (ExactCastInfo.RequiresCastToPrimaryBase) {1759    // Base appears in at least two different places. Find the most-derived1760    // object and see if it's a DestDecl. Note that the most-derived object1761    // must be at least as aligned as this base class subobject, and must1762    // have a vptr at offset 0.1763    llvm::Value *PrimaryBase =1764        emitDynamicCastToVoid(CGF, ThisAddr, SrcRecordTy);1765    ThisAddr = Address(PrimaryBase, CGF.VoidPtrTy, ThisAddr.getAlignment());1766    SrcDecl = DestDecl;1767    // This unauthenticated load is unavoidable, so we're relying on the1768    // authenticated load in the dynamic cast to void, and we'll manually1769    // authenticate the resulting v-table at the end of the cast check.1770    PerformPostCastAuthentication = CGF.getLangOpts().PointerAuthCalls;1771    CGPointerAuthInfo StrippingAuthInfo(0, PointerAuthenticationMode::Strip,1772                                        false, false, nullptr);1773    Address VTablePtrPtr = ThisAddr.withElementType(CGF.VoidPtrPtrTy);1774    VTable = CGF.Builder.CreateLoad(VTablePtrPtr, "vtable");1775    if (PerformPostCastAuthentication)1776      VTable = CGF.EmitPointerAuthAuth(StrippingAuthInfo, VTable);1777  } else1778    VTable = CGF.GetVTablePtr(ThisAddr, CGF.DefaultPtrTy, SrcDecl);1779 1780  // Compare the vptr against the expected vptr for the destination type at1781  // this offset.1782  llvm::Constant *ExpectedVTable = getVTableAddressPoint(1783      BaseSubobject(SrcDecl, ExactCastInfo.Offset), DestDecl);1784  llvm::Value *Success = CGF.Builder.CreateICmpEQ(VTable, ExpectedVTable);1785  llvm::Value *AdjustedThisPtr = ThisAddr.emitRawPointer(CGF);1786 1787  if (!ExactCastInfo.Offset.isZero()) {1788    CharUnits::QuantityType Offset = ExactCastInfo.Offset.getQuantity();1789    llvm::Constant *OffsetConstant =1790        llvm::ConstantInt::get(CGF.PtrDiffTy, -Offset);1791    AdjustedThisPtr = CGF.Builder.CreateInBoundsGEP(CGF.CharTy, AdjustedThisPtr,1792                                                    OffsetConstant);1793    PerformPostCastAuthentication = CGF.getLangOpts().PointerAuthCalls;1794  }1795 1796  if (PerformPostCastAuthentication) {1797    // If we've changed the object pointer we authenticate the vtable pointer1798    // of the resulting object.1799    llvm::BasicBlock *NonNullBlock = CGF.Builder.GetInsertBlock();1800    llvm::BasicBlock *PostCastAuthSuccess =1801        CGF.createBasicBlock("dynamic_cast.postauth.success");1802    llvm::BasicBlock *PostCastAuthComplete =1803        CGF.createBasicBlock("dynamic_cast.postauth.complete");1804    CGF.Builder.CreateCondBr(Success, PostCastAuthSuccess,1805                             PostCastAuthComplete);1806    CGF.EmitBlock(PostCastAuthSuccess);1807    Address AdjustedThisAddr =1808        Address(AdjustedThisPtr, CGF.IntPtrTy, CGF.getPointerAlign());1809    AuthenticateVTable(AdjustedThisAddr, DestDecl);1810    CGF.EmitBranch(PostCastAuthComplete);1811    CGF.EmitBlock(PostCastAuthComplete);1812    llvm::PHINode *PHI = CGF.Builder.CreatePHI(AdjustedThisPtr->getType(), 2);1813    PHI->addIncoming(AdjustedThisPtr, PostCastAuthSuccess);1814    llvm::Value *NullValue =1815        llvm::Constant::getNullValue(AdjustedThisPtr->getType());1816    PHI->addIncoming(NullValue, NonNullBlock);1817    AdjustedThisPtr = PHI;1818  }1819  CGF.Builder.CreateCondBr(Success, CastSuccess, CastFail);1820  return AdjustedThisPtr;1821}1822 1823llvm::Value *ItaniumCXXABI::emitDynamicCastToVoid(CodeGenFunction &CGF,1824                                                  Address ThisAddr,1825                                                  QualType SrcRecordTy) {1826  auto *ClassDecl = SrcRecordTy->castAsCXXRecordDecl();1827  llvm::Value *OffsetToTop;1828  if (CGM.getItaniumVTableContext().isRelativeLayout()) {1829    // Get the vtable pointer.1830    llvm::Value *VTable =1831        CGF.GetVTablePtr(ThisAddr, CGF.DefaultPtrTy, ClassDecl);1832 1833    // Get the offset-to-top from the vtable.1834    OffsetToTop =1835        CGF.Builder.CreateConstInBoundsGEP1_32(CGM.Int32Ty, VTable, -2U);1836    OffsetToTop = CGF.Builder.CreateAlignedLoad(1837        CGM.Int32Ty, OffsetToTop, CharUnits::fromQuantity(4), "offset.to.top");1838  } else {1839    llvm::Type *PtrDiffLTy =1840        CGF.ConvertType(CGF.getContext().getPointerDiffType());1841 1842    // Get the vtable pointer.1843    llvm::Value *VTable =1844        CGF.GetVTablePtr(ThisAddr, CGF.DefaultPtrTy, ClassDecl);1845 1846    // Get the offset-to-top from the vtable.1847    OffsetToTop =1848        CGF.Builder.CreateConstInBoundsGEP1_64(PtrDiffLTy, VTable, -2ULL);1849    OffsetToTop = CGF.Builder.CreateAlignedLoad(1850        PtrDiffLTy, OffsetToTop, CGF.getPointerAlign(), "offset.to.top");1851  }1852  // Finally, add the offset to the pointer.1853  return CGF.Builder.CreateInBoundsGEP(CGF.Int8Ty, ThisAddr.emitRawPointer(CGF),1854                                       OffsetToTop);1855}1856 1857bool ItaniumCXXABI::EmitBadCastCall(CodeGenFunction &CGF) {1858  llvm::FunctionCallee Fn = getBadCastFn(CGF);1859  llvm::CallBase *Call = CGF.EmitRuntimeCallOrInvoke(Fn);1860  Call->setDoesNotReturn();1861  CGF.Builder.CreateUnreachable();1862  return true;1863}1864 1865llvm::Value *1866ItaniumCXXABI::GetVirtualBaseClassOffset(CodeGenFunction &CGF,1867                                         Address This,1868                                         const CXXRecordDecl *ClassDecl,1869                                         const CXXRecordDecl *BaseClassDecl) {1870  llvm::Value *VTablePtr = CGF.GetVTablePtr(This, CGM.Int8PtrTy, ClassDecl);1871  CharUnits VBaseOffsetOffset =1872      CGM.getItaniumVTableContext().getVirtualBaseOffsetOffset(ClassDecl,1873                                                               BaseClassDecl);1874  llvm::Value *VBaseOffsetPtr =1875    CGF.Builder.CreateConstGEP1_64(1876        CGF.Int8Ty, VTablePtr, VBaseOffsetOffset.getQuantity(),1877        "vbase.offset.ptr");1878 1879  llvm::Value *VBaseOffset;1880  if (CGM.getItaniumVTableContext().isRelativeLayout()) {1881    VBaseOffset = CGF.Builder.CreateAlignedLoad(1882        CGF.Int32Ty, VBaseOffsetPtr, CharUnits::fromQuantity(4),1883        "vbase.offset");1884  } else {1885    VBaseOffset = CGF.Builder.CreateAlignedLoad(1886        CGM.PtrDiffTy, VBaseOffsetPtr, CGF.getPointerAlign(), "vbase.offset");1887  }1888  return VBaseOffset;1889}1890 1891void ItaniumCXXABI::EmitCXXConstructors(const CXXConstructorDecl *D) {1892  // Just make sure we're in sync with TargetCXXABI.1893  assert(CGM.getTarget().getCXXABI().hasConstructorVariants());1894 1895  // The constructor used for constructing this as a base class;1896  // ignores virtual bases.1897  CGM.EmitGlobal(GlobalDecl(D, Ctor_Base));1898 1899  // The constructor used for constructing this as a complete class;1900  // constructs the virtual bases, then calls the base constructor.1901  if (!D->getParent()->isAbstract()) {1902    // We don't need to emit the complete ctor if the class is abstract.1903    CGM.EmitGlobal(GlobalDecl(D, Ctor_Complete));1904  }1905}1906 1907CGCXXABI::AddedStructorArgCounts1908ItaniumCXXABI::buildStructorSignature(GlobalDecl GD,1909                                      SmallVectorImpl<CanQualType> &ArgTys) {1910  ASTContext &Context = getContext();1911 1912  // All parameters are already in place except VTT, which goes after 'this'.1913  // These are Clang types, so we don't need to worry about sret yet.1914 1915  // Check if we need to add a VTT parameter (which has type global void **).1916  if ((isa<CXXConstructorDecl>(GD.getDecl()) ? GD.getCtorType() == Ctor_Base1917                                             : GD.getDtorType() == Dtor_Base) &&1918      cast<CXXMethodDecl>(GD.getDecl())->getParent()->getNumVBases() != 0) {1919    LangAS AS = CGM.GetGlobalVarAddressSpace(nullptr);1920    QualType Q = Context.getAddrSpaceQualType(Context.VoidPtrTy, AS);1921    ArgTys.insert(ArgTys.begin() + 1,1922                  Context.getPointerType(CanQualType::CreateUnsafe(Q)));1923    return AddedStructorArgCounts::prefix(1);1924  }1925  return AddedStructorArgCounts{};1926}1927 1928void ItaniumCXXABI::EmitCXXDestructors(const CXXDestructorDecl *D) {1929  // The destructor used for destructing this as a base class; ignores1930  // virtual bases.1931  CGM.EmitGlobal(GlobalDecl(D, Dtor_Base));1932 1933  // The destructor used for destructing this as a most-derived class;1934  // call the base destructor and then destructs any virtual bases.1935  CGM.EmitGlobal(GlobalDecl(D, Dtor_Complete));1936 1937  // The destructor in a virtual table is always a 'deleting'1938  // destructor, which calls the complete destructor and then uses the1939  // appropriate operator delete.1940  if (D->isVirtual())1941    CGM.EmitGlobal(GlobalDecl(D, Dtor_Deleting));1942}1943 1944void ItaniumCXXABI::addImplicitStructorParams(CodeGenFunction &CGF,1945                                              QualType &ResTy,1946                                              FunctionArgList &Params) {1947  const CXXMethodDecl *MD = cast<CXXMethodDecl>(CGF.CurGD.getDecl());1948  assert(isa<CXXConstructorDecl>(MD) || isa<CXXDestructorDecl>(MD));1949 1950  // Check if we need a VTT parameter as well.1951  if (NeedsVTTParameter(CGF.CurGD)) {1952    ASTContext &Context = getContext();1953 1954    // FIXME: avoid the fake decl1955    LangAS AS = CGM.GetGlobalVarAddressSpace(nullptr);1956    QualType Q = Context.getAddrSpaceQualType(Context.VoidPtrTy, AS);1957    QualType T = Context.getPointerType(Q);1958    auto *VTTDecl = ImplicitParamDecl::Create(1959        Context, /*DC=*/nullptr, MD->getLocation(), &Context.Idents.get("vtt"),1960        T, ImplicitParamKind::CXXVTT);1961    Params.insert(Params.begin() + 1, VTTDecl);1962    getStructorImplicitParamDecl(CGF) = VTTDecl;1963  }1964}1965 1966void ItaniumCXXABI::EmitInstanceFunctionProlog(CodeGenFunction &CGF) {1967  // Naked functions have no prolog.1968  if (CGF.CurFuncDecl && CGF.CurFuncDecl->hasAttr<NakedAttr>())1969    return;1970 1971  /// Initialize the 'this' slot. In the Itanium C++ ABI, no prologue1972  /// adjustments are required, because they are all handled by thunks.1973  setCXXABIThisValue(CGF, loadIncomingCXXThis(CGF));1974 1975  /// Initialize the 'vtt' slot if needed.1976  if (getStructorImplicitParamDecl(CGF)) {1977    getStructorImplicitParamValue(CGF) = CGF.Builder.CreateLoad(1978        CGF.GetAddrOfLocalVar(getStructorImplicitParamDecl(CGF)), "vtt");1979  }1980 1981  /// If this is a function that the ABI specifies returns 'this', initialize1982  /// the return slot to 'this' at the start of the function.1983  ///1984  /// Unlike the setting of return types, this is done within the ABI1985  /// implementation instead of by clients of CGCXXABI because:1986  /// 1) getThisValue is currently protected1987  /// 2) in theory, an ABI could implement 'this' returns some other way;1988  ///    HasThisReturn only specifies a contract, not the implementation1989  if (HasThisReturn(CGF.CurGD))1990    CGF.Builder.CreateStore(getThisValue(CGF), CGF.ReturnValue);1991}1992 1993CGCXXABI::AddedStructorArgs ItaniumCXXABI::getImplicitConstructorArgs(1994    CodeGenFunction &CGF, const CXXConstructorDecl *D, CXXCtorType Type,1995    bool ForVirtualBase, bool Delegating) {1996  if (!NeedsVTTParameter(GlobalDecl(D, Type)))1997    return AddedStructorArgs{};1998 1999  // Insert the implicit 'vtt' argument as the second argument. Make sure to2000  // correctly reflect its address space, which can differ from generic on2001  // some targets.2002  llvm::Value *VTT =2003      CGF.GetVTTParameter(GlobalDecl(D, Type), ForVirtualBase, Delegating);2004  LangAS AS = CGM.GetGlobalVarAddressSpace(nullptr);2005  QualType Q = getContext().getAddrSpaceQualType(getContext().VoidPtrTy, AS);2006  QualType VTTTy = getContext().getPointerType(Q);2007  return AddedStructorArgs::prefix({{VTT, VTTTy}});2008}2009 2010llvm::Value *ItaniumCXXABI::getCXXDestructorImplicitParam(2011    CodeGenFunction &CGF, const CXXDestructorDecl *DD, CXXDtorType Type,2012    bool ForVirtualBase, bool Delegating) {2013  GlobalDecl GD(DD, Type);2014  return CGF.GetVTTParameter(GD, ForVirtualBase, Delegating);2015}2016 2017void ItaniumCXXABI::EmitDestructorCall(CodeGenFunction &CGF,2018                                       const CXXDestructorDecl *DD,2019                                       CXXDtorType Type, bool ForVirtualBase,2020                                       bool Delegating, Address This,2021                                       QualType ThisTy) {2022  GlobalDecl GD(DD, Type);2023  llvm::Value *VTT =2024      getCXXDestructorImplicitParam(CGF, DD, Type, ForVirtualBase, Delegating);2025  QualType VTTTy = getContext().getPointerType(getContext().VoidPtrTy);2026 2027  CGCallee Callee;2028  if (getContext().getLangOpts().AppleKext &&2029      Type != Dtor_Base && DD->isVirtual())2030    Callee = CGF.BuildAppleKextVirtualDestructorCall(DD, Type, DD->getParent());2031  else2032    Callee = CGCallee::forDirect(CGM.getAddrOfCXXStructor(GD), GD);2033 2034  CGF.EmitCXXDestructorCall(GD, Callee, CGF.getAsNaturalPointerTo(This, ThisTy),2035                            ThisTy, VTT, VTTTy, nullptr);2036}2037 2038// Check if any non-inline method has the specified attribute.2039template <typename T>2040static bool CXXRecordNonInlineHasAttr(const CXXRecordDecl *RD) {2041  for (const auto *D : RD->noload_decls()) {2042    if (const auto *FD = dyn_cast<FunctionDecl>(D)) {2043      if (FD->isInlined() || FD->doesThisDeclarationHaveABody() ||2044          FD->isPureVirtual())2045        continue;2046      if (D->hasAttr<T>())2047        return true;2048    }2049  }2050 2051  return false;2052}2053 2054static void setVTableSelectiveDLLImportExport(CodeGenModule &CGM,2055                                              llvm::GlobalVariable *VTable,2056                                              const CXXRecordDecl *RD) {2057  if (VTable->getDLLStorageClass() !=2058          llvm::GlobalVariable::DefaultStorageClass ||2059      RD->hasAttr<DLLImportAttr>() || RD->hasAttr<DLLExportAttr>())2060    return;2061 2062  if (CGM.getVTables().isVTableExternal(RD)) {2063    if (CXXRecordNonInlineHasAttr<DLLImportAttr>(RD))2064      VTable->setDLLStorageClass(llvm::GlobalValue::DLLImportStorageClass);2065  } else if (CXXRecordNonInlineHasAttr<DLLExportAttr>(RD))2066    VTable->setDLLStorageClass(llvm::GlobalValue::DLLExportStorageClass);2067}2068 2069void ItaniumCXXABI::emitVTableDefinitions(CodeGenVTables &CGVT,2070                                          const CXXRecordDecl *RD) {2071  llvm::GlobalVariable *VTable = getAddrOfVTable(RD, CharUnits());2072  if (VTable->hasInitializer())2073    return;2074 2075  ItaniumVTableContext &VTContext = CGM.getItaniumVTableContext();2076  const VTableLayout &VTLayout = VTContext.getVTableLayout(RD);2077  llvm::GlobalVariable::LinkageTypes Linkage = CGM.getVTableLinkage(RD);2078  llvm::Constant *RTTI =2079      CGM.GetAddrOfRTTIDescriptor(CGM.getContext().getCanonicalTagType(RD));2080 2081  // Create and set the initializer.2082  ConstantInitBuilder builder(CGM);2083  auto components = builder.beginStruct();2084  CGVT.createVTableInitializer(components, VTLayout, RTTI,2085                               llvm::GlobalValue::isLocalLinkage(Linkage));2086  components.finishAndSetAsInitializer(VTable);2087 2088  // Set the correct linkage.2089  VTable->setLinkage(Linkage);2090 2091  if (CGM.supportsCOMDAT() && VTable->isWeakForLinker())2092    VTable->setComdat(CGM.getModule().getOrInsertComdat(VTable->getName()));2093 2094  if (CGM.getTarget().hasPS4DLLImportExport())2095    setVTableSelectiveDLLImportExport(CGM, VTable, RD);2096 2097  // Set the right visibility.2098  CGM.setGVProperties(VTable, RD);2099 2100  // If this is the magic class __cxxabiv1::__fundamental_type_info,2101  // we will emit the typeinfo for the fundamental types. This is the2102  // same behaviour as GCC.2103  const DeclContext *DC = RD->getDeclContext();2104  if (RD->getIdentifier() &&2105      RD->getIdentifier()->isStr("__fundamental_type_info") &&2106      isa<NamespaceDecl>(DC) && cast<NamespaceDecl>(DC)->getIdentifier() &&2107      cast<NamespaceDecl>(DC)->getIdentifier()->isStr("__cxxabiv1") &&2108      DC->getParent()->isTranslationUnit())2109    EmitFundamentalRTTIDescriptors(RD);2110 2111  // Always emit type metadata on non-available_externally definitions, and on2112  // available_externally definitions if we are performing whole program2113  // devirtualization. For WPD we need the type metadata on all vtable2114  // definitions to ensure we associate derived classes with base classes2115  // defined in headers but with a strong definition only in a shared library.2116  if (!VTable->isDeclarationForLinker() ||2117      CGM.getCodeGenOpts().WholeProgramVTables) {2118    CGM.EmitVTableTypeMetadata(RD, VTable, VTLayout);2119    // For available_externally definitions, add the vtable to2120    // @llvm.compiler.used so that it isn't deleted before whole program2121    // analysis.2122    if (VTable->isDeclarationForLinker()) {2123      assert(CGM.getCodeGenOpts().WholeProgramVTables);2124      CGM.addCompilerUsedGlobal(VTable);2125    }2126  }2127 2128  if (VTContext.isRelativeLayout()) {2129    CGVT.RemoveHwasanMetadata(VTable);2130    if (!VTable->isDSOLocal())2131      CGVT.GenerateRelativeVTableAlias(VTable, VTable->getName());2132  }2133 2134  // Emit symbol for debugger only if requested debug info.2135  if (CGDebugInfo *DI = CGM.getModuleDebugInfo())2136    DI->emitVTableSymbol(VTable, RD);2137}2138 2139bool ItaniumCXXABI::isVirtualOffsetNeededForVTableField(2140    CodeGenFunction &CGF, CodeGenFunction::VPtr Vptr) {2141  if (Vptr.NearestVBase == nullptr)2142    return false;2143  return NeedsVTTParameter(CGF.CurGD);2144}2145 2146llvm::Value *ItaniumCXXABI::getVTableAddressPointInStructor(2147    CodeGenFunction &CGF, const CXXRecordDecl *VTableClass, BaseSubobject Base,2148    const CXXRecordDecl *NearestVBase) {2149 2150  if ((Base.getBase()->getNumVBases() || NearestVBase != nullptr) &&2151      NeedsVTTParameter(CGF.CurGD)) {2152    return getVTableAddressPointInStructorWithVTT(CGF, VTableClass, Base,2153                                                  NearestVBase);2154  }2155  return getVTableAddressPoint(Base, VTableClass);2156}2157 2158llvm::Constant *2159ItaniumCXXABI::getVTableAddressPoint(BaseSubobject Base,2160                                     const CXXRecordDecl *VTableClass) {2161  llvm::GlobalValue *VTable = getAddrOfVTable(VTableClass, CharUnits());2162 2163  // Find the appropriate vtable within the vtable group, and the address point2164  // within that vtable.2165  const VTableLayout &Layout =2166      CGM.getItaniumVTableContext().getVTableLayout(VTableClass);2167  VTableLayout::AddressPointLocation AddressPoint =2168      Layout.getAddressPoint(Base);2169  llvm::Value *Indices[] = {2170    llvm::ConstantInt::get(CGM.Int32Ty, 0),2171    llvm::ConstantInt::get(CGM.Int32Ty, AddressPoint.VTableIndex),2172    llvm::ConstantInt::get(CGM.Int32Ty, AddressPoint.AddressPointIndex),2173  };2174 2175  // Add inrange attribute to indicate that only the VTableIndex can be2176  // accessed.2177  unsigned ComponentSize =2178      CGM.getDataLayout().getTypeAllocSize(CGM.getVTableComponentType());2179  unsigned VTableSize =2180      ComponentSize * Layout.getVTableSize(AddressPoint.VTableIndex);2181  unsigned Offset = ComponentSize * AddressPoint.AddressPointIndex;2182  llvm::ConstantRange InRange(2183      llvm::APInt(32, (int)-Offset, true),2184      llvm::APInt(32, (int)(VTableSize - Offset), true));2185  return llvm::ConstantExpr::getGetElementPtr(2186      VTable->getValueType(), VTable, Indices, /*InBounds=*/true, InRange);2187}2188 2189llvm::Value *ItaniumCXXABI::getVTableAddressPointInStructorWithVTT(2190    CodeGenFunction &CGF, const CXXRecordDecl *VTableClass, BaseSubobject Base,2191    const CXXRecordDecl *NearestVBase) {2192  assert((Base.getBase()->getNumVBases() || NearestVBase != nullptr) &&2193         NeedsVTTParameter(CGF.CurGD) && "This class doesn't have VTT");2194 2195  // Get the secondary vpointer index.2196  uint64_t VirtualPointerIndex =2197      CGM.getVTables().getSecondaryVirtualPointerIndex(VTableClass, Base);2198 2199  /// Load the VTT.2200  llvm::Value *VTT = CGF.LoadCXXVTT();2201  if (VirtualPointerIndex)2202    VTT = CGF.Builder.CreateConstInBoundsGEP1_64(CGF.GlobalsVoidPtrTy, VTT,2203                                                 VirtualPointerIndex);2204 2205  // And load the address point from the VTT.2206  llvm::Value *AP =2207      CGF.Builder.CreateAlignedLoad(CGF.GlobalsVoidPtrTy, VTT,2208                                    CGF.getPointerAlign());2209 2210  if (auto &Schema = CGF.CGM.getCodeGenOpts().PointerAuth.CXXVTTVTablePointers) {2211    CGPointerAuthInfo PointerAuth = CGF.EmitPointerAuthInfo(Schema, VTT,2212                                                            GlobalDecl(),2213                                                            QualType());2214    AP = CGF.EmitPointerAuthAuth(PointerAuth, AP);2215  }2216 2217  return AP;2218}2219 2220llvm::GlobalVariable *ItaniumCXXABI::getAddrOfVTable(const CXXRecordDecl *RD,2221                                                     CharUnits VPtrOffset) {2222  assert(VPtrOffset.isZero() && "Itanium ABI only supports zero vptr offsets");2223 2224  llvm::GlobalVariable *&VTable = VTables[RD];2225  if (VTable)2226    return VTable;2227 2228  // Queue up this vtable for possible deferred emission.2229  CGM.addDeferredVTable(RD);2230 2231  SmallString<256> Name;2232  llvm::raw_svector_ostream Out(Name);2233  getMangleContext().mangleCXXVTable(RD, Out);2234 2235  const VTableLayout &VTLayout =2236      CGM.getItaniumVTableContext().getVTableLayout(RD);2237  llvm::Type *VTableType = CGM.getVTables().getVTableType(VTLayout);2238 2239  // Use pointer to global alignment for the vtable. Otherwise we would align2240  // them based on the size of the initializer which doesn't make sense as only2241  // single values are read.2242  unsigned PAlign = CGM.getVtableGlobalVarAlignment();2243 2244  VTable = CGM.CreateOrReplaceCXXRuntimeVariable(2245      Name, VTableType, llvm::GlobalValue::ExternalLinkage,2246      getContext().toCharUnitsFromBits(PAlign).getAsAlign());2247  VTable->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);2248 2249  if (CGM.getTarget().hasPS4DLLImportExport())2250    setVTableSelectiveDLLImportExport(CGM, VTable, RD);2251 2252  CGM.setGVProperties(VTable, RD);2253  return VTable;2254}2255 2256CGCallee ItaniumCXXABI::getVirtualFunctionPointer(CodeGenFunction &CGF,2257                                                  GlobalDecl GD,2258                                                  Address This,2259                                                  llvm::Type *Ty,2260                                                  SourceLocation Loc) {2261  llvm::Type *PtrTy = CGM.GlobalsInt8PtrTy;2262  auto *MethodDecl = cast<CXXMethodDecl>(GD.getDecl());2263  llvm::Value *VTable = CGF.GetVTablePtr(This, PtrTy, MethodDecl->getParent());2264 2265  uint64_t VTableIndex = CGM.getItaniumVTableContext().getMethodVTableIndex(GD);2266  llvm::Value *VFunc, *VTableSlotPtr = nullptr;2267  auto &Schema = CGM.getCodeGenOpts().PointerAuth.CXXVirtualFunctionPointers;2268 2269  llvm::Type *ComponentTy = CGM.getVTables().getVTableComponentType();2270  uint64_t ByteOffset =2271      VTableIndex * CGM.getDataLayout().getTypeSizeInBits(ComponentTy) / 8;2272 2273  if (!Schema && CGF.ShouldEmitVTableTypeCheckedLoad(MethodDecl->getParent())) {2274    VFunc = CGF.EmitVTableTypeCheckedLoad(MethodDecl->getParent(), VTable,2275                                          PtrTy, ByteOffset);2276  } else {2277    CGF.EmitTypeMetadataCodeForVCall(MethodDecl->getParent(), VTable, Loc);2278 2279    llvm::Value *VFuncLoad;2280    if (CGM.getItaniumVTableContext().isRelativeLayout()) {2281      VFuncLoad = CGF.Builder.CreateCall(2282          CGM.getIntrinsic(llvm::Intrinsic::load_relative, {CGM.Int32Ty}),2283          {VTable, llvm::ConstantInt::get(CGM.Int32Ty, ByteOffset)});2284    } else {2285      VTableSlotPtr = CGF.Builder.CreateConstInBoundsGEP1_64(2286          PtrTy, VTable, VTableIndex, "vfn");2287      VFuncLoad = CGF.Builder.CreateAlignedLoad(PtrTy, VTableSlotPtr,2288                                                CGF.getPointerAlign());2289    }2290 2291    // Add !invariant.load md to virtual function load to indicate that2292    // function didn't change inside vtable.2293    // It's safe to add it without -fstrict-vtable-pointers, but it would not2294    // help in devirtualization because it will only matter if we will have 22295    // the same virtual function loads from the same vtable load, which won't2296    // happen without enabled devirtualization with -fstrict-vtable-pointers.2297    if (CGM.getCodeGenOpts().OptimizationLevel > 0 &&2298        CGM.getCodeGenOpts().StrictVTablePointers) {2299      if (auto *VFuncLoadInstr = dyn_cast<llvm::Instruction>(VFuncLoad)) {2300        VFuncLoadInstr->setMetadata(2301            llvm::LLVMContext::MD_invariant_load,2302            llvm::MDNode::get(CGM.getLLVMContext(),2303                              llvm::ArrayRef<llvm::Metadata *>()));2304      }2305    }2306    VFunc = VFuncLoad;2307  }2308 2309  CGPointerAuthInfo PointerAuth;2310  if (Schema) {2311    assert(VTableSlotPtr && "virtual function pointer not set");2312    GD = CGM.getItaniumVTableContext().findOriginalMethod(GD.getCanonicalDecl());2313    PointerAuth = CGF.EmitPointerAuthInfo(Schema, VTableSlotPtr, GD, QualType());2314  }2315  CGCallee Callee(GD, VFunc, PointerAuth);2316  return Callee;2317}2318 2319llvm::Value *ItaniumCXXABI::EmitVirtualDestructorCall(2320    CodeGenFunction &CGF, const CXXDestructorDecl *Dtor, CXXDtorType DtorType,2321    Address This, DeleteOrMemberCallExpr E, llvm::CallBase **CallOrInvoke) {2322  auto *CE = dyn_cast<const CXXMemberCallExpr *>(E);2323  auto *D = dyn_cast<const CXXDeleteExpr *>(E);2324  assert((CE != nullptr) ^ (D != nullptr));2325  assert(CE == nullptr || CE->arguments().empty());2326  assert(DtorType == Dtor_Deleting || DtorType == Dtor_Complete);2327 2328  GlobalDecl GD(Dtor, DtorType);2329  const CGFunctionInfo *FInfo =2330      &CGM.getTypes().arrangeCXXStructorDeclaration(GD);2331  llvm::FunctionType *Ty = CGF.CGM.getTypes().GetFunctionType(*FInfo);2332  CGCallee Callee = CGCallee::forVirtual(CE, GD, This, Ty);2333 2334  QualType ThisTy;2335  if (CE) {2336    ThisTy = CE->getObjectType();2337  } else {2338    ThisTy = D->getDestroyedType();2339  }2340 2341  CGF.EmitCXXDestructorCall(GD, Callee, This.emitRawPointer(CGF), ThisTy,2342                            nullptr, QualType(), nullptr, CallOrInvoke);2343  return nullptr;2344}2345 2346void ItaniumCXXABI::emitVirtualInheritanceTables(const CXXRecordDecl *RD) {2347  CodeGenVTables &VTables = CGM.getVTables();2348  llvm::GlobalVariable *VTT = VTables.GetAddrOfVTT(RD);2349  VTables.EmitVTTDefinition(VTT, CGM.getVTableLinkage(RD), RD);2350}2351 2352bool ItaniumCXXABI::canSpeculativelyEmitVTableAsBaseClass(2353    const CXXRecordDecl *RD) const {2354  // We don't emit available_externally vtables if we are in -fapple-kext mode2355  // because kext mode does not permit devirtualization.2356  if (CGM.getLangOpts().AppleKext)2357    return false;2358 2359  // If the vtable is hidden then it is not safe to emit an available_externally2360  // copy of vtable.2361  if (isVTableHidden(RD))2362    return false;2363 2364  if (CGM.getCodeGenOpts().ForceEmitVTables)2365    return true;2366 2367  // A speculative vtable can only be generated if all virtual inline functions2368  // defined by this class are emitted. The vtable in the final program contains2369  // for each virtual inline function not used in the current TU a function that2370  // is equivalent to the unused function. The function in the actual vtable2371  // does not have to be declared under the same symbol (e.g., a virtual2372  // destructor that can be substituted with its base class's destructor). Since2373  // inline functions are emitted lazily and this emissions does not account for2374  // speculative emission of a vtable, we might generate a speculative vtable2375  // with references to inline functions that are not emitted under that name.2376  // This can lead to problems when devirtualizing a call to such a function,2377  // that result in linking errors. Hence, if there are any unused virtual2378  // inline function, we cannot emit the speculative vtable.2379  // FIXME we can still emit a copy of the vtable if we2380  // can emit definition of the inline functions.2381  if (hasAnyUnusedVirtualInlineFunction(RD))2382    return false;2383 2384  // For a class with virtual bases, we must also be able to speculatively2385  // emit the VTT, because CodeGen doesn't have separate notions of "can emit2386  // the vtable" and "can emit the VTT". For a base subobject, this means we2387  // need to be able to emit non-virtual base vtables.2388  if (RD->getNumVBases()) {2389    for (const auto &B : RD->bases()) {2390      auto *BRD = B.getType()->getAsCXXRecordDecl();2391      assert(BRD && "no class for base specifier");2392      if (B.isVirtual() || !BRD->isDynamicClass())2393        continue;2394      if (!canSpeculativelyEmitVTableAsBaseClass(BRD))2395        return false;2396    }2397  }2398 2399  return true;2400}2401 2402bool ItaniumCXXABI::canSpeculativelyEmitVTable(const CXXRecordDecl *RD) const {2403  if (!canSpeculativelyEmitVTableAsBaseClass(RD))2404    return false;2405 2406  if (RD->shouldEmitInExternalSource())2407    return false;2408 2409  // For a complete-object vtable (or more specifically, for the VTT), we need2410  // to be able to speculatively emit the vtables of all dynamic virtual bases.2411  for (const auto &B : RD->vbases()) {2412    auto *BRD = B.getType()->getAsCXXRecordDecl();2413    assert(BRD && "no class for base specifier");2414    if (!BRD->isDynamicClass())2415      continue;2416    if (!canSpeculativelyEmitVTableAsBaseClass(BRD))2417      return false;2418  }2419 2420  return true;2421}2422static llvm::Value *performTypeAdjustment(CodeGenFunction &CGF,2423                                          Address InitialPtr,2424                                          const CXXRecordDecl *UnadjustedClass,2425                                          int64_t NonVirtualAdjustment,2426                                          int64_t VirtualAdjustment,2427                                          bool IsReturnAdjustment) {2428  if (!NonVirtualAdjustment && !VirtualAdjustment)2429    return InitialPtr.emitRawPointer(CGF);2430 2431  Address V = InitialPtr.withElementType(CGF.Int8Ty);2432 2433  // In a base-to-derived cast, the non-virtual adjustment is applied first.2434  if (NonVirtualAdjustment && !IsReturnAdjustment) {2435    V = CGF.Builder.CreateConstInBoundsByteGEP(V,2436                              CharUnits::fromQuantity(NonVirtualAdjustment));2437  }2438 2439  // Perform the virtual adjustment if we have one.2440  llvm::Value *ResultPtr;2441  if (VirtualAdjustment) {2442    llvm::Value *VTablePtr =2443        CGF.GetVTablePtr(V, CGF.Int8PtrTy, UnadjustedClass);2444 2445    llvm::Value *Offset;2446    llvm::Value *OffsetPtr = CGF.Builder.CreateConstInBoundsGEP1_64(2447        CGF.Int8Ty, VTablePtr, VirtualAdjustment);2448    if (CGF.CGM.getItaniumVTableContext().isRelativeLayout()) {2449      // Load the adjustment offset from the vtable as a 32-bit int.2450      Offset =2451          CGF.Builder.CreateAlignedLoad(CGF.Int32Ty, OffsetPtr,2452                                        CharUnits::fromQuantity(4));2453    } else {2454      llvm::Type *PtrDiffTy =2455          CGF.ConvertType(CGF.getContext().getPointerDiffType());2456 2457      // Load the adjustment offset from the vtable.2458      Offset = CGF.Builder.CreateAlignedLoad(PtrDiffTy, OffsetPtr,2459                                             CGF.getPointerAlign());2460    }2461    // Adjust our pointer.2462    ResultPtr = CGF.Builder.CreateInBoundsGEP(V.getElementType(),2463                                              V.emitRawPointer(CGF), Offset);2464  } else {2465    ResultPtr = V.emitRawPointer(CGF);2466  }2467 2468  // In a derived-to-base conversion, the non-virtual adjustment is2469  // applied second.2470  if (NonVirtualAdjustment && IsReturnAdjustment) {2471    ResultPtr = CGF.Builder.CreateConstInBoundsGEP1_64(CGF.Int8Ty, ResultPtr,2472                                                       NonVirtualAdjustment);2473  }2474 2475  return ResultPtr;2476}2477 2478llvm::Value *2479ItaniumCXXABI::performThisAdjustment(CodeGenFunction &CGF, Address This,2480                                     const CXXRecordDecl *UnadjustedClass,2481                                     const ThunkInfo &TI) {2482  return performTypeAdjustment(CGF, This, UnadjustedClass, TI.This.NonVirtual,2483                               TI.This.Virtual.Itanium.VCallOffsetOffset,2484                               /*IsReturnAdjustment=*/false);2485}2486 2487llvm::Value *2488ItaniumCXXABI::performReturnAdjustment(CodeGenFunction &CGF, Address Ret,2489                                       const CXXRecordDecl *UnadjustedClass,2490                                       const ReturnAdjustment &RA) {2491  return performTypeAdjustment(CGF, Ret, UnadjustedClass, RA.NonVirtual,2492                               RA.Virtual.Itanium.VBaseOffsetOffset,2493                               /*IsReturnAdjustment=*/true);2494}2495 2496void ARMCXXABI::EmitReturnFromThunk(CodeGenFunction &CGF,2497                                    RValue RV, QualType ResultType) {2498  if (!isa<CXXDestructorDecl>(CGF.CurGD.getDecl()))2499    return ItaniumCXXABI::EmitReturnFromThunk(CGF, RV, ResultType);2500 2501  // Destructor thunks in the ARM ABI have indeterminate results.2502  llvm::Type *T = CGF.ReturnValue.getElementType();2503  RValue Undef = RValue::get(llvm::UndefValue::get(T));2504  return ItaniumCXXABI::EmitReturnFromThunk(CGF, Undef, ResultType);2505}2506 2507/************************** Array allocation cookies **************************/2508 2509CharUnits ItaniumCXXABI::getArrayCookieSizeImpl(QualType elementType) {2510  // The array cookie is a size_t; pad that up to the element alignment.2511  // The cookie is actually right-justified in that space.2512  return std::max(CharUnits::fromQuantity(CGM.SizeSizeInBytes),2513                  CGM.getContext().getPreferredTypeAlignInChars(elementType));2514}2515 2516Address ItaniumCXXABI::InitializeArrayCookie(CodeGenFunction &CGF,2517                                             Address NewPtr,2518                                             llvm::Value *NumElements,2519                                             const CXXNewExpr *expr,2520                                             QualType ElementType) {2521  assert(requiresArrayCookie(expr));2522 2523  unsigned AS = NewPtr.getAddressSpace();2524 2525  ASTContext &Ctx = getContext();2526  CharUnits SizeSize = CGF.getSizeSize();2527 2528  // The size of the cookie.2529  CharUnits CookieSize =2530      std::max(SizeSize, Ctx.getPreferredTypeAlignInChars(ElementType));2531  assert(CookieSize == getArrayCookieSizeImpl(ElementType));2532 2533  // Compute an offset to the cookie.2534  Address CookiePtr = NewPtr;2535  CharUnits CookieOffset = CookieSize - SizeSize;2536  if (!CookieOffset.isZero())2537    CookiePtr = CGF.Builder.CreateConstInBoundsByteGEP(CookiePtr, CookieOffset);2538 2539  // Write the number of elements into the appropriate slot.2540  Address NumElementsPtr = CookiePtr.withElementType(CGF.SizeTy);2541  llvm::Instruction *SI = CGF.Builder.CreateStore(NumElements, NumElementsPtr);2542 2543  // Handle the array cookie specially in ASan.2544  if (CGM.getLangOpts().Sanitize.has(SanitizerKind::Address) && AS == 0 &&2545      (expr->getOperatorNew()->isReplaceableGlobalAllocationFunction() ||2546       CGM.getCodeGenOpts().SanitizeAddressPoisonCustomArrayCookie)) {2547    // The store to the CookiePtr does not need to be instrumented.2548    SI->setNoSanitizeMetadata();2549    llvm::FunctionType *FTy =2550        llvm::FunctionType::get(CGM.VoidTy, NumElementsPtr.getType(), false);2551    llvm::FunctionCallee F =2552        CGM.CreateRuntimeFunction(FTy, "__asan_poison_cxx_array_cookie");2553    CGF.Builder.CreateCall(F, NumElementsPtr.emitRawPointer(CGF));2554  }2555 2556  // Finally, compute a pointer to the actual data buffer by skipping2557  // over the cookie completely.2558  return CGF.Builder.CreateConstInBoundsByteGEP(NewPtr, CookieSize);2559}2560 2561llvm::Value *ItaniumCXXABI::readArrayCookieImpl(CodeGenFunction &CGF,2562                                                Address allocPtr,2563                                                CharUnits cookieSize) {2564  // The element size is right-justified in the cookie.2565  Address numElementsPtr = allocPtr;2566  CharUnits numElementsOffset = cookieSize - CGF.getSizeSize();2567  if (!numElementsOffset.isZero())2568    numElementsPtr =2569      CGF.Builder.CreateConstInBoundsByteGEP(numElementsPtr, numElementsOffset);2570 2571  unsigned AS = allocPtr.getAddressSpace();2572  numElementsPtr = numElementsPtr.withElementType(CGF.SizeTy);2573  if (!CGM.getLangOpts().Sanitize.has(SanitizerKind::Address) || AS != 0)2574    return CGF.Builder.CreateLoad(numElementsPtr);2575  // In asan mode emit a function call instead of a regular load and let the2576  // run-time deal with it: if the shadow is properly poisoned return the2577  // cookie, otherwise return 0 to avoid an infinite loop calling DTORs.2578  // We can't simply ignore this load using nosanitize metadata because2579  // the metadata may be lost.2580  llvm::FunctionType *FTy =2581      llvm::FunctionType::get(CGF.SizeTy, CGF.DefaultPtrTy, false);2582  llvm::FunctionCallee F =2583      CGM.CreateRuntimeFunction(FTy, "__asan_load_cxx_array_cookie");2584  return CGF.Builder.CreateCall(F, numElementsPtr.emitRawPointer(CGF));2585}2586 2587CharUnits ARMCXXABI::getArrayCookieSizeImpl(QualType elementType) {2588  // ARM says that the cookie is always:2589  //   struct array_cookie {2590  //     std::size_t element_size; // element_size != 02591  //     std::size_t element_count;2592  //   };2593  // But the base ABI doesn't give anything an alignment greater than2594  // 8, so we can dismiss this as typical ABI-author blindness to2595  // actual language complexity and round up to the element alignment.2596  return std::max(CharUnits::fromQuantity(2 * CGM.SizeSizeInBytes),2597                  CGM.getContext().getTypeAlignInChars(elementType));2598}2599 2600Address ARMCXXABI::InitializeArrayCookie(CodeGenFunction &CGF,2601                                         Address newPtr,2602                                         llvm::Value *numElements,2603                                         const CXXNewExpr *expr,2604                                         QualType elementType) {2605  assert(requiresArrayCookie(expr));2606 2607  // The cookie is always at the start of the buffer.2608  Address cookie = newPtr;2609 2610  // The first element is the element size.2611  cookie = cookie.withElementType(CGF.SizeTy);2612  llvm::Value *elementSize = llvm::ConstantInt::get(CGF.SizeTy,2613                 getContext().getTypeSizeInChars(elementType).getQuantity());2614  CGF.Builder.CreateStore(elementSize, cookie);2615 2616  // The second element is the element count.2617  cookie = CGF.Builder.CreateConstInBoundsGEP(cookie, 1);2618  CGF.Builder.CreateStore(numElements, cookie);2619 2620  // Finally, compute a pointer to the actual data buffer by skipping2621  // over the cookie completely.2622  CharUnits cookieSize = ARMCXXABI::getArrayCookieSizeImpl(elementType);2623  return CGF.Builder.CreateConstInBoundsByteGEP(newPtr, cookieSize);2624}2625 2626llvm::Value *ARMCXXABI::readArrayCookieImpl(CodeGenFunction &CGF,2627                                            Address allocPtr,2628                                            CharUnits cookieSize) {2629  // The number of elements is at offset sizeof(size_t) relative to2630  // the allocated pointer.2631  Address numElementsPtr2632    = CGF.Builder.CreateConstInBoundsByteGEP(allocPtr, CGF.getSizeSize());2633 2634  numElementsPtr = numElementsPtr.withElementType(CGF.SizeTy);2635  return CGF.Builder.CreateLoad(numElementsPtr);2636}2637 2638/*********************** Static local initialization **************************/2639 2640static llvm::FunctionCallee getGuardAcquireFn(CodeGenModule &CGM,2641                                              llvm::PointerType *GuardPtrTy) {2642  // int __cxa_guard_acquire(__guard *guard_object);2643  llvm::FunctionType *FTy =2644    llvm::FunctionType::get(CGM.getTypes().ConvertType(CGM.getContext().IntTy),2645                            GuardPtrTy, /*isVarArg=*/false);2646  return CGM.CreateRuntimeFunction(2647      FTy, "__cxa_guard_acquire",2648      llvm::AttributeList::get(CGM.getLLVMContext(),2649                               llvm::AttributeList::FunctionIndex,2650                               llvm::Attribute::NoUnwind));2651}2652 2653static llvm::FunctionCallee getGuardReleaseFn(CodeGenModule &CGM,2654                                              llvm::PointerType *GuardPtrTy) {2655  // void __cxa_guard_release(__guard *guard_object);2656  llvm::FunctionType *FTy =2657    llvm::FunctionType::get(CGM.VoidTy, GuardPtrTy, /*isVarArg=*/false);2658  return CGM.CreateRuntimeFunction(2659      FTy, "__cxa_guard_release",2660      llvm::AttributeList::get(CGM.getLLVMContext(),2661                               llvm::AttributeList::FunctionIndex,2662                               llvm::Attribute::NoUnwind));2663}2664 2665static llvm::FunctionCallee getGuardAbortFn(CodeGenModule &CGM,2666                                            llvm::PointerType *GuardPtrTy) {2667  // void __cxa_guard_abort(__guard *guard_object);2668  llvm::FunctionType *FTy =2669    llvm::FunctionType::get(CGM.VoidTy, GuardPtrTy, /*isVarArg=*/false);2670  return CGM.CreateRuntimeFunction(2671      FTy, "__cxa_guard_abort",2672      llvm::AttributeList::get(CGM.getLLVMContext(),2673                               llvm::AttributeList::FunctionIndex,2674                               llvm::Attribute::NoUnwind));2675}2676 2677namespace {2678  struct CallGuardAbort final : EHScopeStack::Cleanup {2679    llvm::GlobalVariable *Guard;2680    CallGuardAbort(llvm::GlobalVariable *Guard) : Guard(Guard) {}2681 2682    void Emit(CodeGenFunction &CGF, Flags flags) override {2683      CGF.EmitNounwindRuntimeCall(getGuardAbortFn(CGF.CGM, Guard->getType()),2684                                  Guard);2685    }2686  };2687}2688 2689/// The ARM code here follows the Itanium code closely enough that we2690/// just special-case it at particular places.2691void ItaniumCXXABI::EmitGuardedInit(CodeGenFunction &CGF,2692                                    const VarDecl &D,2693                                    llvm::GlobalVariable *var,2694                                    bool shouldPerformInit) {2695  CGBuilderTy &Builder = CGF.Builder;2696 2697  // Inline variables that weren't instantiated from variable templates have2698  // partially-ordered initialization within their translation unit.2699  bool NonTemplateInline =2700      D.isInline() &&2701      !isTemplateInstantiation(D.getTemplateSpecializationKind());2702 2703  // We only need to use thread-safe statics for local non-TLS variables and2704  // inline variables; other global initialization is always single-threaded2705  // or (through lazy dynamic loading in multiple threads) unsequenced.2706  bool threadsafe = getContext().getLangOpts().ThreadsafeStatics &&2707                    (D.isLocalVarDecl() || NonTemplateInline) &&2708                    !D.getTLSKind();2709 2710  // If we have a global variable with internal linkage and thread-safe statics2711  // are disabled, we can just let the guard variable be of type i8.2712  bool useInt8GuardVariable = !threadsafe && var->hasInternalLinkage();2713 2714  llvm::IntegerType *guardTy;2715  CharUnits guardAlignment;2716  if (useInt8GuardVariable) {2717    guardTy = CGF.Int8Ty;2718    guardAlignment = CharUnits::One();2719  } else {2720    // Guard variables are 64 bits in the generic ABI and size width on ARM2721    // (i.e. 32-bit on AArch32, 64-bit on AArch64).2722    if (UseARMGuardVarABI) {2723      guardTy = CGF.SizeTy;2724      guardAlignment = CGF.getSizeAlign();2725    } else {2726      guardTy = CGF.Int64Ty;2727      guardAlignment =2728          CharUnits::fromQuantity(CGM.getDataLayout().getABITypeAlign(guardTy));2729    }2730  }2731  llvm::PointerType *guardPtrTy = llvm::PointerType::get(2732      CGF.CGM.getLLVMContext(),2733      CGF.CGM.getDataLayout().getDefaultGlobalsAddressSpace());2734 2735  // Create the guard variable if we don't already have it (as we2736  // might if we're double-emitting this function body).2737  llvm::GlobalVariable *guard = CGM.getStaticLocalDeclGuardAddress(&D);2738  if (!guard) {2739    // Mangle the name for the guard.2740    SmallString<256> guardName;2741    {2742      llvm::raw_svector_ostream out(guardName);2743      getMangleContext().mangleStaticGuardVariable(&D, out);2744    }2745 2746    // Create the guard variable with a zero-initializer.2747    // Just absorb linkage, visibility and dll storage class  from the guarded2748    // variable.2749    guard = new llvm::GlobalVariable(CGM.getModule(), guardTy,2750                                     false, var->getLinkage(),2751                                     llvm::ConstantInt::get(guardTy, 0),2752                                     guardName.str());2753    guard->setDSOLocal(var->isDSOLocal());2754    guard->setVisibility(var->getVisibility());2755    guard->setDLLStorageClass(var->getDLLStorageClass());2756    // If the variable is thread-local, so is its guard variable.2757    guard->setThreadLocalMode(var->getThreadLocalMode());2758    guard->setAlignment(guardAlignment.getAsAlign());2759 2760    // The ABI says: "It is suggested that it be emitted in the same COMDAT2761    // group as the associated data object." In practice, this doesn't work for2762    // non-ELF and non-Wasm object formats, so only do it for ELF and Wasm.2763    llvm::Comdat *C = var->getComdat();2764    if (!D.isLocalVarDecl() && C &&2765        (CGM.getTarget().getTriple().isOSBinFormatELF() ||2766         CGM.getTarget().getTriple().isOSBinFormatWasm())) {2767      guard->setComdat(C);2768    } else if (CGM.supportsCOMDAT() && guard->isWeakForLinker()) {2769      guard->setComdat(CGM.getModule().getOrInsertComdat(guard->getName()));2770    }2771 2772    CGM.setStaticLocalDeclGuardAddress(&D, guard);2773  }2774 2775  Address guardAddr = Address(guard, guard->getValueType(), guardAlignment);2776 2777  // Test whether the variable has completed initialization.2778  //2779  // Itanium C++ ABI 3.3.2:2780  //   The following is pseudo-code showing how these functions can be used:2781  //     if (obj_guard.first_byte == 0) {2782  //       if ( __cxa_guard_acquire (&obj_guard) ) {2783  //         try {2784  //           ... initialize the object ...;2785  //         } catch (...) {2786  //            __cxa_guard_abort (&obj_guard);2787  //            throw;2788  //         }2789  //         ... queue object destructor with __cxa_atexit() ...;2790  //         __cxa_guard_release (&obj_guard);2791  //       }2792  //     }2793  //2794  // If threadsafe statics are enabled, but we don't have inline atomics, just2795  // call __cxa_guard_acquire unconditionally.  The "inline" check isn't2796  // actually inline, and the user might not expect calls to __atomic libcalls.2797 2798  unsigned MaxInlineWidthInBits = CGF.getTarget().getMaxAtomicInlineWidth();2799  llvm::BasicBlock *EndBlock = CGF.createBasicBlock("init.end");2800  if (!threadsafe || MaxInlineWidthInBits) {2801    // Load the first byte of the guard variable.2802    llvm::LoadInst *LI =2803        Builder.CreateLoad(guardAddr.withElementType(CGM.Int8Ty));2804 2805    // Itanium ABI:2806    //   An implementation supporting thread-safety on multiprocessor2807    //   systems must also guarantee that references to the initialized2808    //   object do not occur before the load of the initialization flag.2809    //2810    // In LLVM, we do this by marking the load Acquire.2811    if (threadsafe)2812      LI->setAtomic(llvm::AtomicOrdering::Acquire);2813 2814    // For ARM, we should only check the first bit, rather than the entire byte:2815    //2816    // ARM C++ ABI 3.2.3.1:2817    //   To support the potential use of initialization guard variables2818    //   as semaphores that are the target of ARM SWP and LDREX/STREX2819    //   synchronizing instructions we define a static initialization2820    //   guard variable to be a 4-byte aligned, 4-byte word with the2821    //   following inline access protocol.2822    //     #define INITIALIZED 12823    //     if ((obj_guard & INITIALIZED) != INITIALIZED) {2824    //       if (__cxa_guard_acquire(&obj_guard))2825    //         ...2826    //     }2827    //2828    // and similarly for ARM64:2829    //2830    // ARM64 C++ ABI 3.2.2:2831    //   This ABI instead only specifies the value bit 0 of the static guard2832    //   variable; all other bits are platform defined. Bit 0 shall be 0 when the2833    //   variable is not initialized and 1 when it is.2834    llvm::Value *V =2835        (UseARMGuardVarABI && !useInt8GuardVariable)2836            ? Builder.CreateAnd(LI, llvm::ConstantInt::get(CGM.Int8Ty, 1))2837            : LI;2838    llvm::Value *NeedsInit = Builder.CreateIsNull(V, "guard.uninitialized");2839 2840    llvm::BasicBlock *InitCheckBlock = CGF.createBasicBlock("init.check");2841 2842    // Check if the first byte of the guard variable is zero.2843    CGF.EmitCXXGuardedInitBranch(NeedsInit, InitCheckBlock, EndBlock,2844                                 CodeGenFunction::GuardKind::VariableGuard, &D);2845 2846    CGF.EmitBlock(InitCheckBlock);2847  }2848 2849  // The semantics of dynamic initialization of variables with static or thread2850  // storage duration depends on whether they are declared at block-scope. The2851  // initialization of such variables at block-scope can be aborted with an2852  // exception and later retried (per C++20 [stmt.dcl]p4), and recursive entry2853  // to their initialization has undefined behavior (also per C++202854  // [stmt.dcl]p4). For such variables declared at non-block scope, exceptions2855  // lead to termination (per C++20 [except.terminate]p1), and recursive2856  // references to the variables are governed only by the lifetime rules (per2857  // C++20 [class.cdtor]p2), which means such references are perfectly fine as2858  // long as they avoid touching memory. As a result, block-scope variables must2859  // not be marked as initialized until after initialization completes (unless2860  // the mark is reverted following an exception), but non-block-scope variables2861  // must be marked prior to initialization so that recursive accesses during2862  // initialization do not restart initialization.2863 2864  // Variables used when coping with thread-safe statics and exceptions.2865  if (threadsafe) {2866    // Call __cxa_guard_acquire.2867    llvm::Value *V2868      = CGF.EmitNounwindRuntimeCall(getGuardAcquireFn(CGM, guardPtrTy), guard);2869 2870    llvm::BasicBlock *InitBlock = CGF.createBasicBlock("init");2871 2872    Builder.CreateCondBr(Builder.CreateIsNotNull(V, "tobool"),2873                         InitBlock, EndBlock);2874 2875    // Call __cxa_guard_abort along the exceptional edge.2876    CGF.EHStack.pushCleanup<CallGuardAbort>(EHCleanup, guard);2877 2878    CGF.EmitBlock(InitBlock);2879  } else if (!D.isLocalVarDecl()) {2880    // For non-local variables, store 1 into the first byte of the guard2881    // variable before the object initialization begins so that references2882    // to the variable during initialization don't restart initialization.2883    Builder.CreateStore(llvm::ConstantInt::get(CGM.Int8Ty, 1),2884                        guardAddr.withElementType(CGM.Int8Ty));2885  }2886 2887  // Emit the initializer and add a global destructor if appropriate.2888  CGF.EmitCXXGlobalVarDeclInit(D, var, shouldPerformInit);2889 2890  if (threadsafe) {2891    // Pop the guard-abort cleanup if we pushed one.2892    CGF.PopCleanupBlock();2893 2894    // Call __cxa_guard_release.  This cannot throw.2895    CGF.EmitNounwindRuntimeCall(getGuardReleaseFn(CGM, guardPtrTy),2896                                guardAddr.emitRawPointer(CGF));2897  } else if (D.isLocalVarDecl()) {2898    // For local variables, store 1 into the first byte of the guard variable2899    // after the object initialization completes so that initialization is2900    // retried if initialization is interrupted by an exception.2901    Builder.CreateStore(llvm::ConstantInt::get(CGM.Int8Ty, 1),2902                        guardAddr.withElementType(CGM.Int8Ty));2903  }2904 2905  CGF.EmitBlock(EndBlock);2906}2907 2908/// Register a global destructor using __cxa_atexit.2909static void emitGlobalDtorWithCXAAtExit(CodeGenFunction &CGF,2910                                        llvm::FunctionCallee dtor,2911                                        llvm::Constant *addr, bool TLS) {2912  assert(!CGF.getTarget().getTriple().isOSAIX() &&2913         "unexpected call to emitGlobalDtorWithCXAAtExit");2914  assert((TLS || CGF.getTypes().getCodeGenOpts().CXAAtExit) &&2915         "__cxa_atexit is disabled");2916  const char *Name = "__cxa_atexit";2917  if (TLS) {2918    const llvm::Triple &T = CGF.getTarget().getTriple();2919    Name = T.isOSDarwin() ?  "_tlv_atexit" : "__cxa_thread_atexit";2920  }2921 2922  // We're assuming that the destructor function is something we can2923  // reasonably call with the default CC.2924  llvm::Type *dtorTy = CGF.DefaultPtrTy;2925 2926  // Preserve address space of addr.2927  auto AddrAS = addr ? addr->getType()->getPointerAddressSpace() : 0;2928  auto AddrPtrTy = AddrAS ? llvm::PointerType::get(CGF.getLLVMContext(), AddrAS)2929                          : CGF.Int8PtrTy;2930 2931  // Create a variable that binds the atexit to this shared object.2932  llvm::Constant *handle =2933      CGF.CGM.CreateRuntimeVariable(CGF.Int8Ty, "__dso_handle");2934  auto *GV = cast<llvm::GlobalValue>(handle->stripPointerCasts());2935  GV->setVisibility(llvm::GlobalValue::HiddenVisibility);2936 2937  // extern "C" int __cxa_atexit(void (*f)(void *), void *p, void *d);2938  llvm::Type *paramTys[] = {dtorTy, AddrPtrTy, handle->getType()};2939  llvm::FunctionType *atexitTy =2940    llvm::FunctionType::get(CGF.IntTy, paramTys, false);2941 2942  // Fetch the actual function.2943  llvm::FunctionCallee atexit = CGF.CGM.CreateRuntimeFunction(atexitTy, Name);2944  if (llvm::Function *fn = dyn_cast<llvm::Function>(atexit.getCallee()))2945    fn->setDoesNotThrow();2946 2947  const auto &Context = CGF.CGM.getContext();2948  FunctionProtoType::ExtProtoInfo EPI(Context.getDefaultCallingConvention(2949      /*IsVariadic=*/false, /*IsCXXMethod=*/false));2950  QualType fnType =2951      Context.getFunctionType(Context.VoidTy, {Context.VoidPtrTy}, EPI);2952  llvm::Constant *dtorCallee = cast<llvm::Constant>(dtor.getCallee());2953  dtorCallee = CGF.CGM.getFunctionPointer(dtorCallee, fnType);2954 2955  if (!addr)2956    // addr is null when we are trying to register a dtor annotated with2957    // __attribute__((destructor)) in a constructor function. Using null here is2958    // okay because this argument is just passed back to the destructor2959    // function.2960    addr = llvm::Constant::getNullValue(CGF.Int8PtrTy);2961 2962  llvm::Value *args[] = {dtorCallee, addr, handle};2963  CGF.EmitNounwindRuntimeCall(atexit, args);2964}2965 2966static llvm::Function *createGlobalInitOrCleanupFn(CodeGen::CodeGenModule &CGM,2967                                                   StringRef FnName) {2968  // Create a function that registers/unregisters destructors that have the same2969  // priority.2970  llvm::FunctionType *FTy = llvm::FunctionType::get(CGM.VoidTy, false);2971  llvm::Function *GlobalInitOrCleanupFn = CGM.CreateGlobalInitOrCleanUpFunction(2972      FTy, FnName, CGM.getTypes().arrangeNullaryFunction(), SourceLocation());2973 2974  return GlobalInitOrCleanupFn;2975}2976 2977void CodeGenModule::unregisterGlobalDtorsWithUnAtExit() {2978  for (const auto &I : DtorsUsingAtExit) {2979    int Priority = I.first;2980    std::string GlobalCleanupFnName =2981        std::string("__GLOBAL_cleanup_") + llvm::to_string(Priority);2982 2983    llvm::Function *GlobalCleanupFn =2984        createGlobalInitOrCleanupFn(*this, GlobalCleanupFnName);2985 2986    CodeGenFunction CGF(*this);2987    CGF.StartFunction(GlobalDecl(), getContext().VoidTy, GlobalCleanupFn,2988                      getTypes().arrangeNullaryFunction(), FunctionArgList(),2989                      SourceLocation(), SourceLocation());2990    auto AL = ApplyDebugLocation::CreateArtificial(CGF);2991 2992    // Get the destructor function type, void(*)(void).2993    llvm::FunctionType *dtorFuncTy = llvm::FunctionType::get(CGF.VoidTy, false);2994 2995    // Destructor functions are run/unregistered in non-ascending2996    // order of their priorities.2997    const llvm::TinyPtrVector<llvm::Function *> &Dtors = I.second;2998    auto itv = Dtors.rbegin();2999    while (itv != Dtors.rend()) {3000      llvm::Function *Dtor = *itv;3001 3002      // We're assuming that the destructor function is something we can3003      // reasonably call with the correct CC.3004      llvm::Value *V = CGF.unregisterGlobalDtorWithUnAtExit(Dtor);3005      llvm::Value *NeedsDestruct =3006          CGF.Builder.CreateIsNull(V, "needs_destruct");3007 3008      llvm::BasicBlock *DestructCallBlock =3009          CGF.createBasicBlock("destruct.call");3010      llvm::BasicBlock *EndBlock = CGF.createBasicBlock(3011          (itv + 1) != Dtors.rend() ? "unatexit.call" : "destruct.end");3012      // Check if unatexit returns a value of 0. If it does, jump to3013      // DestructCallBlock, otherwise jump to EndBlock directly.3014      CGF.Builder.CreateCondBr(NeedsDestruct, DestructCallBlock, EndBlock);3015 3016      CGF.EmitBlock(DestructCallBlock);3017 3018      // Emit the call to casted Dtor.3019      llvm::CallInst *CI = CGF.Builder.CreateCall(dtorFuncTy, Dtor);3020      // Make sure the call and the callee agree on calling convention.3021      CI->setCallingConv(Dtor->getCallingConv());3022 3023      CGF.EmitBlock(EndBlock);3024 3025      itv++;3026    }3027 3028    CGF.FinishFunction();3029    AddGlobalDtor(GlobalCleanupFn, Priority);3030  }3031}3032 3033void CodeGenModule::registerGlobalDtorsWithAtExit() {3034  for (const auto &I : DtorsUsingAtExit) {3035    int Priority = I.first;3036    std::string GlobalInitFnName =3037        std::string("__GLOBAL_init_") + llvm::to_string(Priority);3038    llvm::Function *GlobalInitFn =3039        createGlobalInitOrCleanupFn(*this, GlobalInitFnName);3040 3041    CodeGenFunction CGF(*this);3042    CGF.StartFunction(GlobalDecl(), getContext().VoidTy, GlobalInitFn,3043                      getTypes().arrangeNullaryFunction(), FunctionArgList(),3044                      SourceLocation(), SourceLocation());3045    auto AL = ApplyDebugLocation::CreateArtificial(CGF);3046 3047    // Since constructor functions are run in non-descending order of their3048    // priorities, destructors are registered in non-descending order of their3049    // priorities, and since destructor functions are run in the reverse order3050    // of their registration, destructor functions are run in non-ascending3051    // order of their priorities.3052    const llvm::TinyPtrVector<llvm::Function *> &Dtors = I.second;3053    for (auto *Dtor : Dtors) {3054      // Register the destructor function calling __cxa_atexit if it is3055      // available. Otherwise fall back on calling atexit.3056      if (getCodeGenOpts().CXAAtExit) {3057        emitGlobalDtorWithCXAAtExit(CGF, Dtor, nullptr, false);3058      } else {3059        // We're assuming that the destructor function is something we can3060        // reasonably call with the correct CC.3061        CGF.registerGlobalDtorWithAtExit(Dtor);3062      }3063    }3064 3065    CGF.FinishFunction();3066    AddGlobalCtor(GlobalInitFn, Priority);3067  }3068 3069  if (getCXXABI().useSinitAndSterm())3070    unregisterGlobalDtorsWithUnAtExit();3071}3072 3073/// Register a global destructor as best as we know how.3074void ItaniumCXXABI::registerGlobalDtor(CodeGenFunction &CGF, const VarDecl &D,3075                                       llvm::FunctionCallee dtor,3076                                       llvm::Constant *addr) {3077  if (D.isNoDestroy(CGM.getContext()))3078    return;3079 3080  // HLSL doesn't support atexit.3081  if (CGM.getLangOpts().HLSL)3082    return CGM.AddCXXDtorEntry(dtor, addr);3083 3084  // OpenMP offloading supports C++ constructors and destructors but we do not3085  // always have 'atexit' available. Instead lower these to use the LLVM global3086  // destructors which we can handle directly in the runtime. Note that this is3087  // not strictly 1-to-1 with using `atexit` because we no longer tear down3088  // globals in reverse order of when they were constructed.3089  if (!CGM.getLangOpts().hasAtExit() && !D.isStaticLocal())3090    return CGF.registerGlobalDtorWithLLVM(D, dtor, addr);3091 3092  // emitGlobalDtorWithCXAAtExit will emit a call to either __cxa_thread_atexit3093  // or __cxa_atexit depending on whether this VarDecl is a thread-local storage3094  // or not. CXAAtExit controls only __cxa_atexit, so use it if it is enabled.3095  // We can always use __cxa_thread_atexit.3096  if (CGM.getCodeGenOpts().CXAAtExit || D.getTLSKind())3097    return emitGlobalDtorWithCXAAtExit(CGF, dtor, addr, D.getTLSKind());3098 3099  // In Apple kexts, we want to add a global destructor entry.3100  // FIXME: shouldn't this be guarded by some variable?3101  if (CGM.getLangOpts().AppleKext) {3102    // Generate a global destructor entry.3103    return CGM.AddCXXDtorEntry(dtor, addr);3104  }3105 3106  CGF.registerGlobalDtorWithAtExit(D, dtor, addr);3107}3108 3109static bool isThreadWrapperReplaceable(const VarDecl *VD,3110                                       CodeGen::CodeGenModule &CGM) {3111  assert(!VD->isStaticLocal() && "static local VarDecls don't need wrappers!");3112  // Darwin prefers to have references to thread local variables to go through3113  // the thread wrapper instead of directly referencing the backing variable.3114  return VD->getTLSKind() == VarDecl::TLS_Dynamic &&3115         CGM.getTarget().getTriple().isOSDarwin();3116}3117 3118/// Get the appropriate linkage for the wrapper function. This is essentially3119/// the weak form of the variable's linkage; every translation unit which needs3120/// the wrapper emits a copy, and we want the linker to merge them.3121static llvm::GlobalValue::LinkageTypes3122getThreadLocalWrapperLinkage(const VarDecl *VD, CodeGen::CodeGenModule &CGM) {3123  llvm::GlobalValue::LinkageTypes VarLinkage =3124      CGM.getLLVMLinkageVarDefinition(VD);3125 3126  // For internal linkage variables, we don't need an external or weak wrapper.3127  if (llvm::GlobalValue::isLocalLinkage(VarLinkage))3128    return VarLinkage;3129 3130  // If the thread wrapper is replaceable, give it appropriate linkage.3131  if (isThreadWrapperReplaceable(VD, CGM))3132    if (!llvm::GlobalVariable::isLinkOnceLinkage(VarLinkage) &&3133        !llvm::GlobalVariable::isWeakODRLinkage(VarLinkage))3134      return VarLinkage;3135  return llvm::GlobalValue::WeakODRLinkage;3136}3137 3138llvm::Function *3139ItaniumCXXABI::getOrCreateThreadLocalWrapper(const VarDecl *VD,3140                                             llvm::Value *Val) {3141  // Mangle the name for the thread_local wrapper function.3142  SmallString<256> WrapperName;3143  {3144    llvm::raw_svector_ostream Out(WrapperName);3145    getMangleContext().mangleItaniumThreadLocalWrapper(VD, Out);3146  }3147 3148  // FIXME: If VD is a definition, we should regenerate the function attributes3149  // before returning.3150  if (llvm::Value *V = CGM.getModule().getNamedValue(WrapperName))3151    return cast<llvm::Function>(V);3152 3153  QualType RetQT = VD->getType();3154  if (RetQT->isReferenceType())3155    RetQT = RetQT.getNonReferenceType();3156 3157  const CGFunctionInfo &FI = CGM.getTypes().arrangeBuiltinFunctionDeclaration(3158      getContext().getPointerType(RetQT), FunctionArgList());3159 3160  llvm::FunctionType *FnTy = CGM.getTypes().GetFunctionType(FI);3161  llvm::Function *Wrapper =3162      llvm::Function::Create(FnTy, getThreadLocalWrapperLinkage(VD, CGM),3163                             WrapperName.str(), &CGM.getModule());3164 3165  if (CGM.supportsCOMDAT() && Wrapper->isWeakForLinker())3166    Wrapper->setComdat(CGM.getModule().getOrInsertComdat(Wrapper->getName()));3167 3168  CGM.SetLLVMFunctionAttributes(GlobalDecl(), FI, Wrapper, /*IsThunk=*/false);3169 3170  // Always resolve references to the wrapper at link time.3171  if (!Wrapper->hasLocalLinkage())3172    if (!isThreadWrapperReplaceable(VD, CGM) ||3173        llvm::GlobalVariable::isLinkOnceLinkage(Wrapper->getLinkage()) ||3174        llvm::GlobalVariable::isWeakODRLinkage(Wrapper->getLinkage()) ||3175        VD->getVisibility() == HiddenVisibility)3176      Wrapper->setVisibility(llvm::GlobalValue::HiddenVisibility);3177 3178  if (isThreadWrapperReplaceable(VD, CGM)) {3179    Wrapper->setCallingConv(llvm::CallingConv::CXX_FAST_TLS);3180    Wrapper->addFnAttr(llvm::Attribute::NoUnwind);3181  }3182 3183  ThreadWrappers.push_back({VD, Wrapper});3184  return Wrapper;3185}3186 3187void ItaniumCXXABI::EmitThreadLocalInitFuncs(3188    CodeGenModule &CGM, ArrayRef<const VarDecl *> CXXThreadLocals,3189    ArrayRef<llvm::Function *> CXXThreadLocalInits,3190    ArrayRef<const VarDecl *> CXXThreadLocalInitVars) {3191  llvm::Function *InitFunc = nullptr;3192 3193  // Separate initializers into those with ordered (or partially-ordered)3194  // initialization and those with unordered initialization.3195  llvm::SmallVector<llvm::Function *, 8> OrderedInits;3196  llvm::SmallDenseMap<const VarDecl *, llvm::Function *> UnorderedInits;3197  for (unsigned I = 0; I != CXXThreadLocalInits.size(); ++I) {3198    if (isTemplateInstantiation(3199            CXXThreadLocalInitVars[I]->getTemplateSpecializationKind()))3200      UnorderedInits[CXXThreadLocalInitVars[I]->getCanonicalDecl()] =3201          CXXThreadLocalInits[I];3202    else3203      OrderedInits.push_back(CXXThreadLocalInits[I]);3204  }3205 3206  if (!OrderedInits.empty()) {3207    // Generate a guarded initialization function.3208    llvm::FunctionType *FTy =3209        llvm::FunctionType::get(CGM.VoidTy, /*isVarArg=*/false);3210    const CGFunctionInfo &FI = CGM.getTypes().arrangeNullaryFunction();3211    InitFunc = CGM.CreateGlobalInitOrCleanUpFunction(FTy, "__tls_init", FI,3212                                                     SourceLocation(),3213                                                     /*TLS=*/true);3214    llvm::GlobalVariable *Guard = new llvm::GlobalVariable(3215        CGM.getModule(), CGM.Int8Ty, /*isConstant=*/false,3216        llvm::GlobalVariable::InternalLinkage,3217        llvm::ConstantInt::get(CGM.Int8Ty, 0), "__tls_guard");3218    Guard->setThreadLocal(true);3219    Guard->setThreadLocalMode(CGM.GetDefaultLLVMTLSModel());3220 3221    CharUnits GuardAlign = CharUnits::One();3222    Guard->setAlignment(GuardAlign.getAsAlign());3223 3224    CodeGenFunction(CGM).GenerateCXXGlobalInitFunc(3225        InitFunc, OrderedInits, ConstantAddress(Guard, CGM.Int8Ty, GuardAlign));3226    // On Darwin platforms, use CXX_FAST_TLS calling convention.3227    if (CGM.getTarget().getTriple().isOSDarwin()) {3228      InitFunc->setCallingConv(llvm::CallingConv::CXX_FAST_TLS);3229      InitFunc->addFnAttr(llvm::Attribute::NoUnwind);3230    }3231  }3232 3233  // Create declarations for thread wrappers for all thread-local variables3234  // with non-discardable definitions in this translation unit.3235  for (const VarDecl *VD : CXXThreadLocals) {3236    if (VD->hasDefinition() &&3237        !isDiscardableGVALinkage(getContext().GetGVALinkageForVariable(VD))) {3238      llvm::GlobalValue *GV = CGM.GetGlobalValue(CGM.getMangledName(VD));3239      getOrCreateThreadLocalWrapper(VD, GV);3240    }3241  }3242 3243  // Emit all referenced thread wrappers.3244  for (auto VDAndWrapper : ThreadWrappers) {3245    const VarDecl *VD = VDAndWrapper.first;3246    llvm::GlobalVariable *Var =3247        cast<llvm::GlobalVariable>(CGM.GetGlobalValue(CGM.getMangledName(VD)));3248    llvm::Function *Wrapper = VDAndWrapper.second;3249 3250    // Some targets require that all access to thread local variables go through3251    // the thread wrapper.  This means that we cannot attempt to create a thread3252    // wrapper or a thread helper.3253    if (!VD->hasDefinition()) {3254      if (isThreadWrapperReplaceable(VD, CGM)) {3255        Wrapper->setLinkage(llvm::Function::ExternalLinkage);3256        continue;3257      }3258 3259      // If this isn't a TU in which this variable is defined, the thread3260      // wrapper is discardable.3261      if (Wrapper->getLinkage() == llvm::Function::WeakODRLinkage)3262        Wrapper->setLinkage(llvm::Function::LinkOnceODRLinkage);3263    }3264 3265    CGM.SetLLVMFunctionAttributesForDefinition(nullptr, Wrapper);3266 3267    // Mangle the name for the thread_local initialization function.3268    SmallString<256> InitFnName;3269    {3270      llvm::raw_svector_ostream Out(InitFnName);3271      getMangleContext().mangleItaniumThreadLocalInit(VD, Out);3272    }3273 3274    llvm::FunctionType *InitFnTy = llvm::FunctionType::get(CGM.VoidTy, false);3275 3276    // If we have a definition for the variable, emit the initialization3277    // function as an alias to the global Init function (if any). Otherwise,3278    // produce a declaration of the initialization function.3279    llvm::GlobalValue *Init = nullptr;3280    bool InitIsInitFunc = false;3281    bool HasConstantInitialization = false;3282    if (!usesThreadWrapperFunction(VD)) {3283      HasConstantInitialization = true;3284    } else if (VD->hasDefinition()) {3285      InitIsInitFunc = true;3286      llvm::Function *InitFuncToUse = InitFunc;3287      if (isTemplateInstantiation(VD->getTemplateSpecializationKind()))3288        InitFuncToUse = UnorderedInits.lookup(VD->getCanonicalDecl());3289      if (InitFuncToUse)3290        Init = llvm::GlobalAlias::create(Var->getLinkage(), InitFnName.str(),3291                                         InitFuncToUse);3292    } else {3293      // Emit a weak global function referring to the initialization function.3294      // This function will not exist if the TU defining the thread_local3295      // variable in question does not need any dynamic initialization for3296      // its thread_local variables.3297      Init = llvm::Function::Create(InitFnTy,3298                                    llvm::GlobalVariable::ExternalWeakLinkage,3299                                    InitFnName.str(), &CGM.getModule());3300      const CGFunctionInfo &FI = CGM.getTypes().arrangeNullaryFunction();3301      CGM.SetLLVMFunctionAttributes(3302          GlobalDecl(), FI, cast<llvm::Function>(Init), /*IsThunk=*/false);3303    }3304 3305    if (Init) {3306      Init->setVisibility(Var->getVisibility());3307      // Don't mark an extern_weak function DSO local on windows.3308      if (!CGM.getTriple().isOSWindows() || !Init->hasExternalWeakLinkage())3309        Init->setDSOLocal(Var->isDSOLocal());3310    }3311 3312    llvm::LLVMContext &Context = CGM.getModule().getContext();3313 3314    // The linker on AIX is not happy with missing weak symbols.  However,3315    // other TUs will not know whether the initialization routine exists3316    // so create an empty, init function to satisfy the linker.3317    // This is needed whenever a thread wrapper function is not used, and3318    // also when the symbol is weak.3319    if (CGM.getTriple().isOSAIX() && VD->hasDefinition() &&3320        isEmittedWithConstantInitializer(VD, true) &&3321        !mayNeedDestruction(VD)) {3322      // Init should be null.  If it were non-null, then the logic above would3323      // either be defining the function to be an alias or declaring the3324      // function with the expectation that the definition of the variable3325      // is elsewhere.3326      assert(Init == nullptr && "Expected Init to be null.");3327 3328      llvm::Function *Func = llvm::Function::Create(3329          InitFnTy, Var->getLinkage(), InitFnName.str(), &CGM.getModule());3330      const CGFunctionInfo &FI = CGM.getTypes().arrangeNullaryFunction();3331      CGM.SetLLVMFunctionAttributes(GlobalDecl(), FI,3332                                    cast<llvm::Function>(Func),3333                                    /*IsThunk=*/false);3334      // Create a function body that just returns3335      llvm::BasicBlock *Entry = llvm::BasicBlock::Create(Context, "", Func);3336      CGBuilderTy Builder(CGM, Entry);3337      Builder.CreateRetVoid();3338    }3339 3340    llvm::BasicBlock *Entry = llvm::BasicBlock::Create(Context, "", Wrapper);3341    CGBuilderTy Builder(CGM, Entry);3342    if (HasConstantInitialization) {3343      // No dynamic initialization to invoke.3344    } else if (InitIsInitFunc) {3345      if (Init) {3346        llvm::CallInst *CallVal = Builder.CreateCall(InitFnTy, Init);3347        if (isThreadWrapperReplaceable(VD, CGM)) {3348          CallVal->setCallingConv(llvm::CallingConv::CXX_FAST_TLS);3349          llvm::Function *Fn =3350              cast<llvm::Function>(cast<llvm::GlobalAlias>(Init)->getAliasee());3351          Fn->setCallingConv(llvm::CallingConv::CXX_FAST_TLS);3352        }3353      }3354    } else if (CGM.getTriple().isOSAIX()) {3355      // On AIX, except if constinit and also neither of class type or of3356      // (possibly multi-dimensional) array of class type, thread_local vars3357      // will have init routines regardless of whether they are3358      // const-initialized.  Since the routine is guaranteed to exist, we can3359      // unconditionally call it without testing for its existance.  This3360      // avoids potentially unresolved weak symbols which the AIX linker3361      // isn't happy with.3362      Builder.CreateCall(InitFnTy, Init);3363    } else {3364      // Don't know whether we have an init function. Call it if it exists.3365      llvm::Value *Have = Builder.CreateIsNotNull(Init);3366      llvm::BasicBlock *InitBB = llvm::BasicBlock::Create(Context, "", Wrapper);3367      llvm::BasicBlock *ExitBB = llvm::BasicBlock::Create(Context, "", Wrapper);3368      Builder.CreateCondBr(Have, InitBB, ExitBB);3369 3370      Builder.SetInsertPoint(InitBB);3371      Builder.CreateCall(InitFnTy, Init);3372      Builder.CreateBr(ExitBB);3373 3374      Builder.SetInsertPoint(ExitBB);3375    }3376 3377    // For a reference, the result of the wrapper function is a pointer to3378    // the referenced object.3379    llvm::Value *Val = Builder.CreateThreadLocalAddress(Var);3380 3381    if (VD->getType()->isReferenceType()) {3382      CharUnits Align = CGM.getContext().getDeclAlign(VD);3383      Val = Builder.CreateAlignedLoad(Var->getValueType(), Val, Align);3384    }3385    Val = Builder.CreateAddrSpaceCast(Val, Wrapper->getReturnType());3386 3387    Builder.CreateRet(Val);3388  }3389}3390 3391LValue ItaniumCXXABI::EmitThreadLocalVarDeclLValue(CodeGenFunction &CGF,3392                                                   const VarDecl *VD,3393                                                   QualType LValType) {3394  llvm::Value *Val = CGF.CGM.GetAddrOfGlobalVar(VD);3395  llvm::Function *Wrapper = getOrCreateThreadLocalWrapper(VD, Val);3396 3397  llvm::CallInst *CallVal = CGF.Builder.CreateCall(Wrapper);3398  CallVal->setCallingConv(Wrapper->getCallingConv());3399 3400  LValue LV;3401  if (VD->getType()->isReferenceType())3402    LV = CGF.MakeNaturalAlignRawAddrLValue(CallVal, LValType);3403  else3404    LV = CGF.MakeRawAddrLValue(CallVal, LValType,3405                               CGF.getContext().getDeclAlign(VD));3406  // FIXME: need setObjCGCLValueClass?3407  return LV;3408}3409 3410/// Return whether the given global decl needs a VTT parameter, which it does3411/// if it's a base constructor or destructor with virtual bases.3412bool ItaniumCXXABI::NeedsVTTParameter(GlobalDecl GD) {3413  const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());3414 3415  // We don't have any virtual bases, just return early.3416  if (!MD->getParent()->getNumVBases())3417    return false;3418 3419  // Check if we have a base constructor.3420  if (isa<CXXConstructorDecl>(MD) && GD.getCtorType() == Ctor_Base)3421    return true;3422 3423  // Check if we have a base destructor.3424  if (isa<CXXDestructorDecl>(MD) && GD.getDtorType() == Dtor_Base)3425    return true;3426 3427  return false;3428}3429 3430llvm::Constant *3431ItaniumCXXABI::getOrCreateVirtualFunctionPointerThunk(const CXXMethodDecl *MD) {3432  SmallString<256> MethodName;3433  llvm::raw_svector_ostream Out(MethodName);3434  getMangleContext().mangleCXXName(MD, Out);3435  MethodName += "_vfpthunk_";3436  StringRef ThunkName = MethodName.str();3437  llvm::Function *ThunkFn;3438  if ((ThunkFn = cast_or_null<llvm::Function>(3439           CGM.getModule().getNamedValue(ThunkName))))3440    return ThunkFn;3441 3442  const CGFunctionInfo &FnInfo = CGM.getTypes().arrangeCXXMethodDeclaration(MD);3443  llvm::FunctionType *ThunkTy = CGM.getTypes().GetFunctionType(FnInfo);3444  llvm::GlobalValue::LinkageTypes Linkage =3445      MD->isExternallyVisible() ? llvm::GlobalValue::LinkOnceODRLinkage3446                                : llvm::GlobalValue::InternalLinkage;3447  ThunkFn =3448      llvm::Function::Create(ThunkTy, Linkage, ThunkName, &CGM.getModule());3449  if (Linkage == llvm::GlobalValue::LinkOnceODRLinkage)3450    ThunkFn->setVisibility(llvm::GlobalValue::HiddenVisibility);3451  assert(ThunkFn->getName() == ThunkName && "name was uniqued!");3452 3453  CGM.SetLLVMFunctionAttributes(MD, FnInfo, ThunkFn, /*IsThunk=*/true);3454  CGM.SetLLVMFunctionAttributesForDefinition(MD, ThunkFn);3455 3456  // Stack protection sometimes gets inserted after the musttail call.3457  ThunkFn->removeFnAttr(llvm::Attribute::StackProtect);3458  ThunkFn->removeFnAttr(llvm::Attribute::StackProtectStrong);3459  ThunkFn->removeFnAttr(llvm::Attribute::StackProtectReq);3460 3461  // Start codegen.3462  CodeGenFunction CGF(CGM);3463  CGF.CurGD = GlobalDecl(MD);3464  CGF.CurFuncIsThunk = true;3465 3466  // Build FunctionArgs.3467  FunctionArgList FunctionArgs;3468  CGF.BuildFunctionArgList(CGF.CurGD, FunctionArgs);3469 3470  CGF.StartFunction(GlobalDecl(), FnInfo.getReturnType(), ThunkFn, FnInfo,3471                    FunctionArgs, MD->getLocation(), SourceLocation());3472  llvm::Value *ThisVal = loadIncomingCXXThis(CGF);3473  setCXXABIThisValue(CGF, ThisVal);3474 3475  CallArgList CallArgs;3476  for (const VarDecl *VD : FunctionArgs)3477    CGF.EmitDelegateCallArg(CallArgs, VD, SourceLocation());3478 3479  const FunctionProtoType *FPT = MD->getType()->getAs<FunctionProtoType>();3480  RequiredArgs Required = RequiredArgs::forPrototypePlus(FPT, /*this*/ 1);3481  const CGFunctionInfo &CallInfo =3482      CGM.getTypes().arrangeCXXMethodCall(CallArgs, FPT, Required, 0);3483  CGCallee Callee = CGCallee::forVirtual(nullptr, GlobalDecl(MD),3484                                         getThisAddress(CGF), ThunkTy);3485  llvm::CallBase *CallOrInvoke;3486  CGF.EmitCall(CallInfo, Callee, ReturnValueSlot(), CallArgs, &CallOrInvoke,3487               /*IsMustTail=*/true, SourceLocation(), true);3488  auto *Call = cast<llvm::CallInst>(CallOrInvoke);3489  Call->setTailCallKind(llvm::CallInst::TCK_MustTail);3490  if (Call->getType()->isVoidTy())3491    CGF.Builder.CreateRetVoid();3492  else3493    CGF.Builder.CreateRet(Call);3494 3495  // Finish the function to maintain CodeGenFunction invariants.3496  // FIXME: Don't emit unreachable code.3497  CGF.EmitBlock(CGF.createBasicBlock());3498  CGF.FinishFunction();3499  return ThunkFn;3500}3501 3502namespace {3503class ItaniumRTTIBuilder {3504  CodeGenModule &CGM;  // Per-module state.3505  llvm::LLVMContext &VMContext;3506  const ItaniumCXXABI &CXXABI;  // Per-module state.3507 3508  /// Fields - The fields of the RTTI descriptor currently being built.3509  SmallVector<llvm::Constant *, 16> Fields;3510 3511  /// GetAddrOfTypeName - Returns the mangled type name of the given type.3512  llvm::GlobalVariable *3513  GetAddrOfTypeName(QualType Ty, llvm::GlobalVariable::LinkageTypes Linkage);3514 3515  /// GetAddrOfExternalRTTIDescriptor - Returns the constant for the RTTI3516  /// descriptor of the given type.3517  llvm::Constant *GetAddrOfExternalRTTIDescriptor(QualType Ty);3518 3519  /// BuildVTablePointer - Build the vtable pointer for the given type.3520  void BuildVTablePointer(const Type *Ty, llvm::Constant *StorageAddress);3521 3522  /// BuildSIClassTypeInfo - Build an abi::__si_class_type_info, used for single3523  /// inheritance, according to the Itanium C++ ABI, 2.9.5p6b.3524  void BuildSIClassTypeInfo(const CXXRecordDecl *RD);3525 3526  /// BuildVMIClassTypeInfo - Build an abi::__vmi_class_type_info, used for3527  /// classes with bases that do not satisfy the abi::__si_class_type_info3528  /// constraints, according ti the Itanium C++ ABI, 2.9.5p5c.3529  void BuildVMIClassTypeInfo(const CXXRecordDecl *RD);3530 3531  /// BuildPointerTypeInfo - Build an abi::__pointer_type_info struct, used3532  /// for pointer types.3533  void BuildPointerTypeInfo(QualType PointeeTy);3534 3535  /// BuildObjCObjectTypeInfo - Build the appropriate kind of3536  /// type_info for an object type.3537  void BuildObjCObjectTypeInfo(const ObjCObjectType *Ty);3538 3539  /// BuildPointerToMemberTypeInfo - Build an abi::__pointer_to_member_type_info3540  /// struct, used for member pointer types.3541  void BuildPointerToMemberTypeInfo(const MemberPointerType *Ty);3542 3543public:3544  ItaniumRTTIBuilder(const ItaniumCXXABI &ABI)3545      : CGM(ABI.CGM), VMContext(CGM.getModule().getContext()), CXXABI(ABI) {}3546 3547  // Pointer type info flags.3548  enum {3549    /// PTI_Const - Type has const qualifier.3550    PTI_Const = 0x1,3551 3552    /// PTI_Volatile - Type has volatile qualifier.3553    PTI_Volatile = 0x2,3554 3555    /// PTI_Restrict - Type has restrict qualifier.3556    PTI_Restrict = 0x4,3557 3558    /// PTI_Incomplete - Type is incomplete.3559    PTI_Incomplete = 0x8,3560 3561    /// PTI_ContainingClassIncomplete - Containing class is incomplete.3562    /// (in pointer to member).3563    PTI_ContainingClassIncomplete = 0x10,3564 3565    /// PTI_TransactionSafe - Pointee is transaction_safe function (C++ TM TS).3566    //PTI_TransactionSafe = 0x20,3567 3568    /// PTI_Noexcept - Pointee is noexcept function (C++1z).3569    PTI_Noexcept = 0x40,3570  };3571 3572  // VMI type info flags.3573  enum {3574    /// VMI_NonDiamondRepeat - Class has non-diamond repeated inheritance.3575    VMI_NonDiamondRepeat = 0x1,3576 3577    /// VMI_DiamondShaped - Class is diamond shaped.3578    VMI_DiamondShaped = 0x23579  };3580 3581  // Base class type info flags.3582  enum {3583    /// BCTI_Virtual - Base class is virtual.3584    BCTI_Virtual = 0x1,3585 3586    /// BCTI_Public - Base class is public.3587    BCTI_Public = 0x23588  };3589 3590  /// BuildTypeInfo - Build the RTTI type info struct for the given type, or3591  /// link to an existing RTTI descriptor if one already exists.3592  llvm::Constant *BuildTypeInfo(QualType Ty);3593 3594  /// BuildTypeInfo - Build the RTTI type info struct for the given type.3595  llvm::Constant *BuildTypeInfo(3596      QualType Ty,3597      llvm::GlobalVariable::LinkageTypes Linkage,3598      llvm::GlobalValue::VisibilityTypes Visibility,3599      llvm::GlobalValue::DLLStorageClassTypes DLLStorageClass);3600};3601}3602 3603llvm::GlobalVariable *ItaniumRTTIBuilder::GetAddrOfTypeName(3604    QualType Ty, llvm::GlobalVariable::LinkageTypes Linkage) {3605  SmallString<256> Name;3606  llvm::raw_svector_ostream Out(Name);3607  CGM.getCXXABI().getMangleContext().mangleCXXRTTIName(Ty, Out);3608 3609  // We know that the mangled name of the type starts at index 4 of the3610  // mangled name of the typename, so we can just index into it in order to3611  // get the mangled name of the type.3612  llvm::Constant *Init = llvm::ConstantDataArray::getString(VMContext,3613                                                            Name.substr(4));3614  auto Align = CGM.getContext().getTypeAlignInChars(CGM.getContext().CharTy);3615 3616  llvm::GlobalVariable *GV = CGM.CreateOrReplaceCXXRuntimeVariable(3617      Name, Init->getType(), Linkage, Align.getAsAlign());3618 3619  GV->setInitializer(Init);3620 3621  return GV;3622}3623 3624llvm::Constant *3625ItaniumRTTIBuilder::GetAddrOfExternalRTTIDescriptor(QualType Ty) {3626  // Mangle the RTTI name.3627  SmallString<256> Name;3628  llvm::raw_svector_ostream Out(Name);3629  CGM.getCXXABI().getMangleContext().mangleCXXRTTI(Ty, Out);3630 3631  // Look for an existing global.3632  llvm::GlobalVariable *GV = CGM.getModule().getNamedGlobal(Name);3633 3634  if (!GV) {3635    // Create a new global variable.3636    // Note for the future: If we would ever like to do deferred emission of3637    // RTTI, check if emitting vtables opportunistically need any adjustment.3638 3639    GV = new llvm::GlobalVariable(3640        CGM.getModule(), CGM.GlobalsInt8PtrTy,3641        /*isConstant=*/true, llvm::GlobalValue::ExternalLinkage, nullptr, Name);3642    const CXXRecordDecl *RD = Ty->getAsCXXRecordDecl();3643    CGM.setGVProperties(GV, RD);3644    // Import the typeinfo symbol when all non-inline virtual methods are3645    // imported.3646    if (CGM.getTarget().hasPS4DLLImportExport()) {3647      if (RD && CXXRecordNonInlineHasAttr<DLLImportAttr>(RD)) {3648        GV->setDLLStorageClass(llvm::GlobalVariable::DLLImportStorageClass);3649        CGM.setDSOLocal(GV);3650      }3651    }3652  }3653 3654  return GV;3655}3656 3657/// TypeInfoIsInStandardLibrary - Given a builtin type, returns whether the type3658/// info for that type is defined in the standard library.3659static bool TypeInfoIsInStandardLibrary(const BuiltinType *Ty) {3660  // Itanium C++ ABI 2.9.2:3661  //   Basic type information (e.g. for "int", "bool", etc.) will be kept in3662  //   the run-time support library. Specifically, the run-time support3663  //   library should contain type_info objects for the types X, X* and3664  //   X const*, for every X in: void, std::nullptr_t, bool, wchar_t, char,3665  //   unsigned char, signed char, short, unsigned short, int, unsigned int,3666  //   long, unsigned long, long long, unsigned long long, float, double,3667  //   long double, char16_t, char32_t, and the IEEE 754r decimal and3668  //   half-precision floating point types.3669  //3670  // GCC also emits RTTI for __int128.3671  // FIXME: We do not emit RTTI information for decimal types here.3672 3673  // Types added here must also be added to EmitFundamentalRTTIDescriptors.3674  switch (Ty->getKind()) {3675    case BuiltinType::Void:3676    case BuiltinType::NullPtr:3677    case BuiltinType::Bool:3678    case BuiltinType::WChar_S:3679    case BuiltinType::WChar_U:3680    case BuiltinType::Char_U:3681    case BuiltinType::Char_S:3682    case BuiltinType::UChar:3683    case BuiltinType::SChar:3684    case BuiltinType::Short:3685    case BuiltinType::UShort:3686    case BuiltinType::Int:3687    case BuiltinType::UInt:3688    case BuiltinType::Long:3689    case BuiltinType::ULong:3690    case BuiltinType::LongLong:3691    case BuiltinType::ULongLong:3692    case BuiltinType::Half:3693    case BuiltinType::Float:3694    case BuiltinType::Double:3695    case BuiltinType::LongDouble:3696    case BuiltinType::Float16:3697    case BuiltinType::Float128:3698    case BuiltinType::Ibm128:3699    case BuiltinType::Char8:3700    case BuiltinType::Char16:3701    case BuiltinType::Char32:3702    case BuiltinType::Int128:3703    case BuiltinType::UInt128:3704      return true;3705 3706#define IMAGE_TYPE(ImgType, Id, SingletonId, Access, Suffix) \3707    case BuiltinType::Id:3708#include "clang/Basic/OpenCLImageTypes.def"3709#define EXT_OPAQUE_TYPE(ExtType, Id, Ext) \3710    case BuiltinType::Id:3711#include "clang/Basic/OpenCLExtensionTypes.def"3712    case BuiltinType::OCLSampler:3713    case BuiltinType::OCLEvent:3714    case BuiltinType::OCLClkEvent:3715    case BuiltinType::OCLQueue:3716    case BuiltinType::OCLReserveID:3717#define SVE_TYPE(Name, Id, SingletonId) \3718    case BuiltinType::Id:3719#include "clang/Basic/AArch64ACLETypes.def"3720#define PPC_VECTOR_TYPE(Name, Id, Size) \3721    case BuiltinType::Id:3722#include "clang/Basic/PPCTypes.def"3723#define RVV_TYPE(Name, Id, SingletonId) case BuiltinType::Id:3724#include "clang/Basic/RISCVVTypes.def"3725#define WASM_TYPE(Name, Id, SingletonId) case BuiltinType::Id:3726#include "clang/Basic/WebAssemblyReferenceTypes.def"3727#define AMDGPU_TYPE(Name, Id, SingletonId, Width, Align) case BuiltinType::Id:3728#include "clang/Basic/AMDGPUTypes.def"3729#define HLSL_INTANGIBLE_TYPE(Name, Id, SingletonId) case BuiltinType::Id:3730#include "clang/Basic/HLSLIntangibleTypes.def"3731    case BuiltinType::ShortAccum:3732    case BuiltinType::Accum:3733    case BuiltinType::LongAccum:3734    case BuiltinType::UShortAccum:3735    case BuiltinType::UAccum:3736    case BuiltinType::ULongAccum:3737    case BuiltinType::ShortFract:3738    case BuiltinType::Fract:3739    case BuiltinType::LongFract:3740    case BuiltinType::UShortFract:3741    case BuiltinType::UFract:3742    case BuiltinType::ULongFract:3743    case BuiltinType::SatShortAccum:3744    case BuiltinType::SatAccum:3745    case BuiltinType::SatLongAccum:3746    case BuiltinType::SatUShortAccum:3747    case BuiltinType::SatUAccum:3748    case BuiltinType::SatULongAccum:3749    case BuiltinType::SatShortFract:3750    case BuiltinType::SatFract:3751    case BuiltinType::SatLongFract:3752    case BuiltinType::SatUShortFract:3753    case BuiltinType::SatUFract:3754    case BuiltinType::SatULongFract:3755    case BuiltinType::BFloat16:3756      return false;3757 3758    case BuiltinType::Dependent:3759#define BUILTIN_TYPE(Id, SingletonId)3760#define PLACEHOLDER_TYPE(Id, SingletonId) \3761    case BuiltinType::Id:3762#include "clang/AST/BuiltinTypes.def"3763      llvm_unreachable("asking for RRTI for a placeholder type!");3764 3765    case BuiltinType::ObjCId:3766    case BuiltinType::ObjCClass:3767    case BuiltinType::ObjCSel:3768      llvm_unreachable("FIXME: Objective-C types are unsupported!");3769  }3770 3771  llvm_unreachable("Invalid BuiltinType Kind!");3772}3773 3774static bool TypeInfoIsInStandardLibrary(const PointerType *PointerTy) {3775  QualType PointeeTy = PointerTy->getPointeeType();3776  const BuiltinType *BuiltinTy = dyn_cast<BuiltinType>(PointeeTy);3777  if (!BuiltinTy)3778    return false;3779 3780  // Check the qualifiers.3781  Qualifiers Quals = PointeeTy.getQualifiers();3782  Quals.removeConst();3783 3784  if (!Quals.empty())3785    return false;3786 3787  return TypeInfoIsInStandardLibrary(BuiltinTy);3788}3789 3790/// IsStandardLibraryRTTIDescriptor - Returns whether the type3791/// information for the given type exists in the standard library.3792static bool IsStandardLibraryRTTIDescriptor(QualType Ty) {3793  // Type info for builtin types is defined in the standard library.3794  if (const BuiltinType *BuiltinTy = dyn_cast<BuiltinType>(Ty))3795    return TypeInfoIsInStandardLibrary(BuiltinTy);3796 3797  // Type info for some pointer types to builtin types is defined in the3798  // standard library.3799  if (const PointerType *PointerTy = dyn_cast<PointerType>(Ty))3800    return TypeInfoIsInStandardLibrary(PointerTy);3801 3802  return false;3803}3804 3805/// ShouldUseExternalRTTIDescriptor - Returns whether the type information for3806/// the given type exists somewhere else, and that we should not emit the type3807/// information in this translation unit.  Assumes that it is not a3808/// standard-library type.3809static bool ShouldUseExternalRTTIDescriptor(CodeGenModule &CGM,3810                                            QualType Ty) {3811  ASTContext &Context = CGM.getContext();3812 3813  // If RTTI is disabled, assume it might be disabled in the3814  // translation unit that defines any potential key function, too.3815  if (!Context.getLangOpts().RTTI) return false;3816 3817  if (const RecordType *RecordTy = dyn_cast<RecordType>(Ty)) {3818    const CXXRecordDecl *RD =3819        cast<CXXRecordDecl>(RecordTy->getDecl())->getDefinitionOrSelf();3820    if (!RD->hasDefinition())3821      return false;3822 3823    if (!RD->isDynamicClass())3824      return false;3825 3826    // FIXME: this may need to be reconsidered if the key function3827    // changes.3828    // N.B. We must always emit the RTTI data ourselves if there exists a key3829    // function.3830    bool IsDLLImport = RD->hasAttr<DLLImportAttr>();3831 3832    // Don't import the RTTI but emit it locally.3833    if (CGM.getTriple().isOSCygMing())3834      return false;3835 3836    if (CGM.getVTables().isVTableExternal(RD)) {3837      if (CGM.getTarget().hasPS4DLLImportExport())3838        return true;3839 3840      return IsDLLImport && !CGM.getTriple().isWindowsItaniumEnvironment()3841                 ? false3842                 : true;3843    }3844    if (IsDLLImport)3845      return true;3846  }3847 3848  return false;3849}3850 3851/// IsIncompleteClassType - Returns whether the given record type is incomplete.3852static bool IsIncompleteClassType(const RecordType *RecordTy) {3853  return !RecordTy->getDecl()->getDefinitionOrSelf()->isCompleteDefinition();3854}3855 3856/// ContainsIncompleteClassType - Returns whether the given type contains an3857/// incomplete class type. This is true if3858///3859///   * The given type is an incomplete class type.3860///   * The given type is a pointer type whose pointee type contains an3861///     incomplete class type.3862///   * The given type is a member pointer type whose class is an incomplete3863///     class type.3864///   * The given type is a member pointer type whoise pointee type contains an3865///     incomplete class type.3866/// is an indirect or direct pointer to an incomplete class type.3867static bool ContainsIncompleteClassType(QualType Ty) {3868  if (const RecordType *RecordTy = dyn_cast<RecordType>(Ty)) {3869    if (IsIncompleteClassType(RecordTy))3870      return true;3871  }3872 3873  if (const PointerType *PointerTy = dyn_cast<PointerType>(Ty))3874    return ContainsIncompleteClassType(PointerTy->getPointeeType());3875 3876  if (const MemberPointerType *MemberPointerTy =3877      dyn_cast<MemberPointerType>(Ty)) {3878    // Check if the class type is incomplete.3879    if (!MemberPointerTy->getMostRecentCXXRecordDecl()->hasDefinition())3880      return true;3881 3882    return ContainsIncompleteClassType(MemberPointerTy->getPointeeType());3883  }3884 3885  return false;3886}3887 3888// CanUseSingleInheritance - Return whether the given record decl has a "single,3889// public, non-virtual base at offset zero (i.e. the derived class is dynamic3890// iff the base is)", according to Itanium C++ ABI, 2.95p6b.3891static bool CanUseSingleInheritance(const CXXRecordDecl *RD) {3892  // Check the number of bases.3893  if (RD->getNumBases() != 1)3894    return false;3895 3896  // Get the base.3897  CXXRecordDecl::base_class_const_iterator Base = RD->bases_begin();3898 3899  // Check that the base is not virtual.3900  if (Base->isVirtual())3901    return false;3902 3903  // Check that the base is public.3904  if (Base->getAccessSpecifier() != AS_public)3905    return false;3906 3907  // Check that the class is dynamic iff the base is.3908  auto *BaseDecl = Base->getType()->castAsCXXRecordDecl();3909  if (!BaseDecl->isEmpty() &&3910      BaseDecl->isDynamicClass() != RD->isDynamicClass())3911    return false;3912 3913  return true;3914}3915 3916void ItaniumRTTIBuilder::BuildVTablePointer(const Type *Ty,3917                                            llvm::Constant *StorageAddress) {3918  // abi::__class_type_info.3919  static const char * const ClassTypeInfo =3920    "_ZTVN10__cxxabiv117__class_type_infoE";3921  // abi::__si_class_type_info.3922  static const char * const SIClassTypeInfo =3923    "_ZTVN10__cxxabiv120__si_class_type_infoE";3924  // abi::__vmi_class_type_info.3925  static const char * const VMIClassTypeInfo =3926    "_ZTVN10__cxxabiv121__vmi_class_type_infoE";3927 3928  const char *VTableName = nullptr;3929 3930  switch (Ty->getTypeClass()) {3931#define TYPE(Class, Base)3932#define ABSTRACT_TYPE(Class, Base)3933#define NON_CANONICAL_UNLESS_DEPENDENT_TYPE(Class, Base) case Type::Class:3934#define NON_CANONICAL_TYPE(Class, Base) case Type::Class:3935#define DEPENDENT_TYPE(Class, Base) case Type::Class:3936#include "clang/AST/TypeNodes.inc"3937    llvm_unreachable("Non-canonical and dependent types shouldn't get here");3938 3939  case Type::LValueReference:3940  case Type::RValueReference:3941    llvm_unreachable("References shouldn't get here");3942 3943  case Type::Auto:3944  case Type::DeducedTemplateSpecialization:3945    llvm_unreachable("Undeduced type shouldn't get here");3946 3947  case Type::Pipe:3948    llvm_unreachable("Pipe types shouldn't get here");3949 3950  case Type::ArrayParameter:3951    llvm_unreachable("Array Parameter types should not get here.");3952 3953  case Type::Builtin:3954  case Type::BitInt:3955  // GCC treats vector and complex types as fundamental types.3956  case Type::Vector:3957  case Type::ExtVector:3958  case Type::ConstantMatrix:3959  case Type::Complex:3960  case Type::Atomic:3961  // FIXME: GCC treats block pointers as fundamental types?!3962  case Type::BlockPointer:3963    // abi::__fundamental_type_info.3964    VTableName = "_ZTVN10__cxxabiv123__fundamental_type_infoE";3965    break;3966 3967  case Type::ConstantArray:3968  case Type::IncompleteArray:3969  case Type::VariableArray:3970    // abi::__array_type_info.3971    VTableName = "_ZTVN10__cxxabiv117__array_type_infoE";3972    break;3973 3974  case Type::FunctionNoProto:3975  case Type::FunctionProto:3976    // abi::__function_type_info.3977    VTableName = "_ZTVN10__cxxabiv120__function_type_infoE";3978    break;3979 3980  case Type::Enum:3981    // abi::__enum_type_info.3982    VTableName = "_ZTVN10__cxxabiv116__enum_type_infoE";3983    break;3984 3985  case Type::Record: {3986    const auto *RD = cast<CXXRecordDecl>(cast<RecordType>(Ty)->getDecl())3987                         ->getDefinitionOrSelf();3988 3989    if (!RD->hasDefinition() || !RD->getNumBases()) {3990      VTableName = ClassTypeInfo;3991    } else if (CanUseSingleInheritance(RD)) {3992      VTableName = SIClassTypeInfo;3993    } else {3994      VTableName = VMIClassTypeInfo;3995    }3996 3997    break;3998  }3999 4000  case Type::ObjCObject:4001    // Ignore protocol qualifiers.4002    Ty = cast<ObjCObjectType>(Ty)->getBaseType().getTypePtr();4003 4004    // Handle id and Class.4005    if (isa<BuiltinType>(Ty)) {4006      VTableName = ClassTypeInfo;4007      break;4008    }4009 4010    assert(isa<ObjCInterfaceType>(Ty));4011    [[fallthrough]];4012 4013  case Type::ObjCInterface:4014    if (cast<ObjCInterfaceType>(Ty)->getDecl()->getSuperClass()) {4015      VTableName = SIClassTypeInfo;4016    } else {4017      VTableName = ClassTypeInfo;4018    }4019    break;4020 4021  case Type::ObjCObjectPointer:4022  case Type::Pointer:4023    // abi::__pointer_type_info.4024    VTableName = "_ZTVN10__cxxabiv119__pointer_type_infoE";4025    break;4026 4027  case Type::MemberPointer:4028    // abi::__pointer_to_member_type_info.4029    VTableName = "_ZTVN10__cxxabiv129__pointer_to_member_type_infoE";4030    break;4031 4032  case Type::HLSLAttributedResource:4033  case Type::HLSLInlineSpirv:4034    llvm_unreachable("HLSL doesn't support virtual functions");4035  }4036 4037  llvm::Constant *VTable = nullptr;4038 4039  // Check if the alias exists. If it doesn't, then get or create the global.4040  if (CGM.getItaniumVTableContext().isRelativeLayout())4041    VTable = CGM.getModule().getNamedAlias(VTableName);4042  if (!VTable) {4043    llvm::Type *Ty = llvm::ArrayType::get(CGM.GlobalsInt8PtrTy, 0);4044    VTable = CGM.getModule().getOrInsertGlobal(VTableName, Ty);4045  }4046 4047  CGM.setDSOLocal(cast<llvm::GlobalValue>(VTable->stripPointerCasts()));4048 4049  llvm::Type *PtrDiffTy =4050      CGM.getTypes().ConvertType(CGM.getContext().getPointerDiffType());4051 4052  // The vtable address point is 2.4053  if (CGM.getItaniumVTableContext().isRelativeLayout()) {4054    // The vtable address point is 8 bytes after its start:4055    // 4 for the offset to top + 4 for the relative offset to rtti.4056    llvm::Constant *Eight = llvm::ConstantInt::get(CGM.Int32Ty, 8);4057    VTable =4058        llvm::ConstantExpr::getInBoundsGetElementPtr(CGM.Int8Ty, VTable, Eight);4059  } else {4060    llvm::Constant *Two = llvm::ConstantInt::get(PtrDiffTy, 2);4061    VTable = llvm::ConstantExpr::getInBoundsGetElementPtr(CGM.GlobalsInt8PtrTy,4062                                                          VTable, Two);4063  }4064 4065  if (const auto &Schema =4066          CGM.getCodeGenOpts().PointerAuth.CXXTypeInfoVTablePointer)4067    VTable = CGM.getConstantSignedPointer(4068        VTable, Schema,4069        Schema.isAddressDiscriminated() ? StorageAddress : nullptr,4070        GlobalDecl(), QualType(Ty, 0));4071 4072  Fields.push_back(VTable);4073}4074 4075/// Return the linkage that the type info and type info name constants4076/// should have for the given type.4077static llvm::GlobalVariable::LinkageTypes getTypeInfoLinkage(CodeGenModule &CGM,4078                                                             QualType Ty) {4079  // Itanium C++ ABI 2.9.5p7:4080  //   In addition, it and all of the intermediate abi::__pointer_type_info4081  //   structs in the chain down to the abi::__class_type_info for the4082  //   incomplete class type must be prevented from resolving to the4083  //   corresponding type_info structs for the complete class type, possibly4084  //   by making them local static objects. Finally, a dummy class RTTI is4085  //   generated for the incomplete type that will not resolve to the final4086  //   complete class RTTI (because the latter need not exist), possibly by4087  //   making it a local static object.4088  if (ContainsIncompleteClassType(Ty))4089    return llvm::GlobalValue::InternalLinkage;4090 4091  switch (Ty->getLinkage()) {4092  case Linkage::Invalid:4093    llvm_unreachable("Linkage hasn't been computed!");4094 4095  case Linkage::None:4096  case Linkage::Internal:4097  case Linkage::UniqueExternal:4098    return llvm::GlobalValue::InternalLinkage;4099 4100  case Linkage::VisibleNone:4101  case Linkage::Module:4102  case Linkage::External:4103    // RTTI is not enabled, which means that this type info struct is going4104    // to be used for exception handling. Give it linkonce_odr linkage.4105    if (!CGM.getLangOpts().RTTI)4106      return llvm::GlobalValue::LinkOnceODRLinkage;4107 4108    if (const RecordType *Record = dyn_cast<RecordType>(Ty)) {4109      const auto *RD =4110          cast<CXXRecordDecl>(Record->getDecl())->getDefinitionOrSelf();4111      if (RD->hasAttr<WeakAttr>())4112        return llvm::GlobalValue::WeakODRLinkage;4113      if (CGM.getTriple().isWindowsItaniumEnvironment())4114        if (RD->hasAttr<DLLImportAttr>() &&4115            ShouldUseExternalRTTIDescriptor(CGM, Ty))4116          return llvm::GlobalValue::ExternalLinkage;4117      // MinGW always uses LinkOnceODRLinkage for type info.4118      if (RD->isDynamicClass() &&4119          !CGM.getContext().getTargetInfo().getTriple().isOSCygMing())4120        return CGM.getVTableLinkage(RD);4121    }4122 4123    return llvm::GlobalValue::LinkOnceODRLinkage;4124  }4125 4126  llvm_unreachable("Invalid linkage!");4127}4128 4129llvm::Constant *ItaniumRTTIBuilder::BuildTypeInfo(QualType Ty) {4130  // We want to operate on the canonical type.4131  Ty = Ty.getCanonicalType();4132 4133  // Check if we've already emitted an RTTI descriptor for this type.4134  SmallString<256> Name;4135  llvm::raw_svector_ostream Out(Name);4136  CGM.getCXXABI().getMangleContext().mangleCXXRTTI(Ty, Out);4137 4138  llvm::GlobalVariable *OldGV = CGM.getModule().getNamedGlobal(Name);4139  if (OldGV && !OldGV->isDeclaration()) {4140    assert(!OldGV->hasAvailableExternallyLinkage() &&4141           "available_externally typeinfos not yet implemented");4142 4143    return OldGV;4144  }4145 4146  // Check if there is already an external RTTI descriptor for this type.4147  if (IsStandardLibraryRTTIDescriptor(Ty) ||4148      ShouldUseExternalRTTIDescriptor(CGM, Ty))4149    return GetAddrOfExternalRTTIDescriptor(Ty);4150 4151  // Emit the standard library with external linkage.4152  llvm::GlobalVariable::LinkageTypes Linkage = getTypeInfoLinkage(CGM, Ty);4153 4154  // Give the type_info object and name the formal visibility of the4155  // type itself.4156  llvm::GlobalValue::VisibilityTypes llvmVisibility;4157  if (llvm::GlobalValue::isLocalLinkage(Linkage))4158    // If the linkage is local, only default visibility makes sense.4159    llvmVisibility = llvm::GlobalValue::DefaultVisibility;4160  else if (CXXABI.classifyRTTIUniqueness(Ty, Linkage) ==4161           ItaniumCXXABI::RUK_NonUniqueHidden)4162    llvmVisibility = llvm::GlobalValue::HiddenVisibility;4163  else4164    llvmVisibility = CodeGenModule::GetLLVMVisibility(Ty->getVisibility());4165 4166  llvm::GlobalValue::DLLStorageClassTypes DLLStorageClass =4167      llvm::GlobalValue::DefaultStorageClass;4168  if (auto RD = Ty->getAsCXXRecordDecl()) {4169    if ((CGM.getTriple().isWindowsItaniumEnvironment() &&4170         RD->hasAttr<DLLExportAttr>()) ||4171        (CGM.shouldMapVisibilityToDLLExport(RD) &&4172         !llvm::GlobalValue::isLocalLinkage(Linkage) &&4173         llvmVisibility == llvm::GlobalValue::DefaultVisibility))4174      DLLStorageClass = llvm::GlobalValue::DLLExportStorageClass;4175  }4176  return BuildTypeInfo(Ty, Linkage, llvmVisibility, DLLStorageClass);4177}4178 4179llvm::Constant *ItaniumRTTIBuilder::BuildTypeInfo(4180      QualType Ty,4181      llvm::GlobalVariable::LinkageTypes Linkage,4182      llvm::GlobalValue::VisibilityTypes Visibility,4183      llvm::GlobalValue::DLLStorageClassTypes DLLStorageClass) {4184  SmallString<256> Name;4185  llvm::raw_svector_ostream Out(Name);4186  CGM.getCXXABI().getMangleContext().mangleCXXRTTI(Ty, Out);4187  llvm::Module &M = CGM.getModule();4188  llvm::GlobalVariable *OldGV = M.getNamedGlobal(Name);4189  // int8 is an arbitrary type to be replaced later with replaceInitializer.4190  llvm::GlobalVariable *GV =4191      new llvm::GlobalVariable(M, CGM.Int8Ty, /*isConstant=*/true, Linkage,4192                               /*Initializer=*/nullptr, Name);4193 4194  // Add the vtable pointer.4195  BuildVTablePointer(cast<Type>(Ty), GV);4196 4197  // And the name.4198  llvm::GlobalVariable *TypeName = GetAddrOfTypeName(Ty, Linkage);4199  llvm::Constant *TypeNameField;4200 4201  // If we're supposed to demote the visibility, be sure to set a flag4202  // to use a string comparison for type_info comparisons.4203  ItaniumCXXABI::RTTIUniquenessKind RTTIUniqueness =4204      CXXABI.classifyRTTIUniqueness(Ty, Linkage);4205  if (RTTIUniqueness != ItaniumCXXABI::RUK_Unique) {4206    // The flag is the sign bit, which on ARM64 is defined to be clear4207    // for global pointers.  This is very ARM64-specific.4208    TypeNameField = llvm::ConstantExpr::getPtrToInt(TypeName, CGM.Int64Ty);4209    llvm::Constant *flag =4210        llvm::ConstantInt::get(CGM.Int64Ty, ((uint64_t)1) << 63);4211    TypeNameField = llvm::ConstantExpr::getAdd(TypeNameField, flag);4212    TypeNameField =4213        llvm::ConstantExpr::getIntToPtr(TypeNameField, CGM.GlobalsInt8PtrTy);4214  } else {4215    TypeNameField = TypeName;4216  }4217  Fields.push_back(TypeNameField);4218 4219  switch (Ty->getTypeClass()) {4220#define TYPE(Class, Base)4221#define ABSTRACT_TYPE(Class, Base)4222#define NON_CANONICAL_UNLESS_DEPENDENT_TYPE(Class, Base) case Type::Class:4223#define NON_CANONICAL_TYPE(Class, Base) case Type::Class:4224#define DEPENDENT_TYPE(Class, Base) case Type::Class:4225#include "clang/AST/TypeNodes.inc"4226    llvm_unreachable("Non-canonical and dependent types shouldn't get here");4227 4228  // GCC treats vector types as fundamental types.4229  case Type::Builtin:4230  case Type::Vector:4231  case Type::ExtVector:4232  case Type::ConstantMatrix:4233  case Type::Complex:4234  case Type::BlockPointer:4235    // Itanium C++ ABI 2.9.5p4:4236    // abi::__fundamental_type_info adds no data members to std::type_info.4237    break;4238 4239  case Type::LValueReference:4240  case Type::RValueReference:4241    llvm_unreachable("References shouldn't get here");4242 4243  case Type::Auto:4244  case Type::DeducedTemplateSpecialization:4245    llvm_unreachable("Undeduced type shouldn't get here");4246 4247  case Type::Pipe:4248    break;4249 4250  case Type::BitInt:4251    break;4252 4253  case Type::ConstantArray:4254  case Type::IncompleteArray:4255  case Type::VariableArray:4256  case Type::ArrayParameter:4257    // Itanium C++ ABI 2.9.5p5:4258    // abi::__array_type_info adds no data members to std::type_info.4259    break;4260 4261  case Type::FunctionNoProto:4262  case Type::FunctionProto:4263    // Itanium C++ ABI 2.9.5p5:4264    // abi::__function_type_info adds no data members to std::type_info.4265    break;4266 4267  case Type::Enum:4268    // Itanium C++ ABI 2.9.5p5:4269    // abi::__enum_type_info adds no data members to std::type_info.4270    break;4271 4272  case Type::Record: {4273    const auto *RD = cast<CXXRecordDecl>(cast<RecordType>(Ty)->getDecl())4274                         ->getDefinitionOrSelf();4275    if (!RD->hasDefinition() || !RD->getNumBases()) {4276      // We don't need to emit any fields.4277      break;4278    }4279 4280    if (CanUseSingleInheritance(RD))4281      BuildSIClassTypeInfo(RD);4282    else4283      BuildVMIClassTypeInfo(RD);4284 4285    break;4286  }4287 4288  case Type::ObjCObject:4289  case Type::ObjCInterface:4290    BuildObjCObjectTypeInfo(cast<ObjCObjectType>(Ty));4291    break;4292 4293  case Type::ObjCObjectPointer:4294    BuildPointerTypeInfo(cast<ObjCObjectPointerType>(Ty)->getPointeeType());4295    break;4296 4297  case Type::Pointer:4298    BuildPointerTypeInfo(cast<PointerType>(Ty)->getPointeeType());4299    break;4300 4301  case Type::MemberPointer:4302    BuildPointerToMemberTypeInfo(cast<MemberPointerType>(Ty));4303    break;4304 4305  case Type::Atomic:4306    // No fields, at least for the moment.4307    break;4308 4309  case Type::HLSLAttributedResource:4310  case Type::HLSLInlineSpirv:4311    llvm_unreachable("HLSL doesn't support RTTI");4312  }4313 4314  GV->replaceInitializer(llvm::ConstantStruct::getAnon(Fields));4315 4316  // Export the typeinfo in the same circumstances as the vtable is exported.4317  auto GVDLLStorageClass = DLLStorageClass;4318  if (CGM.getTarget().hasPS4DLLImportExport() &&4319      GVDLLStorageClass != llvm::GlobalVariable::DLLExportStorageClass) {4320    if (const RecordType *RecordTy = dyn_cast<RecordType>(Ty)) {4321      const auto *RD =4322          cast<CXXRecordDecl>(RecordTy->getDecl())->getDefinitionOrSelf();4323      if (RD->hasAttr<DLLExportAttr>() ||4324          CXXRecordNonInlineHasAttr<DLLExportAttr>(RD))4325        GVDLLStorageClass = llvm::GlobalVariable::DLLExportStorageClass;4326    }4327  }4328 4329  // If there's already an old global variable, replace it with the new one.4330  if (OldGV) {4331    GV->takeName(OldGV);4332    OldGV->replaceAllUsesWith(GV);4333    OldGV->eraseFromParent();4334  }4335 4336  if (CGM.supportsCOMDAT() && GV->isWeakForLinker())4337    GV->setComdat(M.getOrInsertComdat(GV->getName()));4338 4339  CharUnits Align = CGM.getContext().toCharUnitsFromBits(4340      CGM.getTarget().getPointerAlign(CGM.GetGlobalVarAddressSpace(nullptr)));4341  GV->setAlignment(Align.getAsAlign());4342 4343  // The Itanium ABI specifies that type_info objects must be globally4344  // unique, with one exception: if the type is an incomplete class4345  // type or a (possibly indirect) pointer to one.  That exception4346  // affects the general case of comparing type_info objects produced4347  // by the typeid operator, which is why the comparison operators on4348  // std::type_info generally use the type_info name pointers instead4349  // of the object addresses.  However, the language's built-in uses4350  // of RTTI generally require class types to be complete, even when4351  // manipulating pointers to those class types.  This allows the4352  // implementation of dynamic_cast to rely on address equality tests,4353  // which is much faster.4354 4355  // All of this is to say that it's important that both the type_info4356  // object and the type_info name be uniqued when weakly emitted.4357 4358  TypeName->setVisibility(Visibility);4359  CGM.setDSOLocal(TypeName);4360 4361  GV->setVisibility(Visibility);4362  CGM.setDSOLocal(GV);4363 4364  TypeName->setDLLStorageClass(DLLStorageClass);4365  GV->setDLLStorageClass(GVDLLStorageClass);4366 4367  TypeName->setPartition(CGM.getCodeGenOpts().SymbolPartition);4368  GV->setPartition(CGM.getCodeGenOpts().SymbolPartition);4369 4370  return GV;4371}4372 4373/// BuildObjCObjectTypeInfo - Build the appropriate kind of type_info4374/// for the given Objective-C object type.4375void ItaniumRTTIBuilder::BuildObjCObjectTypeInfo(const ObjCObjectType *OT) {4376  // Drop qualifiers.4377  const Type *T = OT->getBaseType().getTypePtr();4378  assert(isa<BuiltinType>(T) || isa<ObjCInterfaceType>(T));4379 4380  // The builtin types are abi::__class_type_infos and don't require4381  // extra fields.4382  if (isa<BuiltinType>(T)) return;4383 4384  ObjCInterfaceDecl *Class = cast<ObjCInterfaceType>(T)->getDecl();4385  ObjCInterfaceDecl *Super = Class->getSuperClass();4386 4387  // Root classes are also __class_type_info.4388  if (!Super) return;4389 4390  QualType SuperTy = CGM.getContext().getObjCInterfaceType(Super);4391 4392  // Everything else is single inheritance.4393  llvm::Constant *BaseTypeInfo =4394      ItaniumRTTIBuilder(CXXABI).BuildTypeInfo(SuperTy);4395  Fields.push_back(BaseTypeInfo);4396}4397 4398/// BuildSIClassTypeInfo - Build an abi::__si_class_type_info, used for single4399/// inheritance, according to the Itanium C++ ABI, 2.95p6b.4400void ItaniumRTTIBuilder::BuildSIClassTypeInfo(const CXXRecordDecl *RD) {4401  // Itanium C++ ABI 2.9.5p6b:4402  // It adds to abi::__class_type_info a single member pointing to the4403  // type_info structure for the base type,4404  llvm::Constant *BaseTypeInfo =4405    ItaniumRTTIBuilder(CXXABI).BuildTypeInfo(RD->bases_begin()->getType());4406  Fields.push_back(BaseTypeInfo);4407}4408 4409namespace {4410  /// SeenBases - Contains virtual and non-virtual bases seen when traversing4411  /// a class hierarchy.4412  struct SeenBases {4413    llvm::SmallPtrSet<const CXXRecordDecl *, 16> NonVirtualBases;4414    llvm::SmallPtrSet<const CXXRecordDecl *, 16> VirtualBases;4415  };4416}4417 4418/// ComputeVMIClassTypeInfoFlags - Compute the value of the flags member in4419/// abi::__vmi_class_type_info.4420///4421static unsigned ComputeVMIClassTypeInfoFlags(const CXXBaseSpecifier *Base,4422                                             SeenBases &Bases) {4423 4424  unsigned Flags = 0;4425 4426  auto *BaseDecl = Base->getType()->castAsCXXRecordDecl();4427  if (Base->isVirtual()) {4428    // Mark the virtual base as seen.4429    if (!Bases.VirtualBases.insert(BaseDecl).second) {4430      // If this virtual base has been seen before, then the class is diamond4431      // shaped.4432      Flags |= ItaniumRTTIBuilder::VMI_DiamondShaped;4433    } else {4434      if (Bases.NonVirtualBases.count(BaseDecl))4435        Flags |= ItaniumRTTIBuilder::VMI_NonDiamondRepeat;4436    }4437  } else {4438    // Mark the non-virtual base as seen.4439    if (!Bases.NonVirtualBases.insert(BaseDecl).second) {4440      // If this non-virtual base has been seen before, then the class has non-4441      // diamond shaped repeated inheritance.4442      Flags |= ItaniumRTTIBuilder::VMI_NonDiamondRepeat;4443    } else {4444      if (Bases.VirtualBases.count(BaseDecl))4445        Flags |= ItaniumRTTIBuilder::VMI_NonDiamondRepeat;4446    }4447  }4448 4449  // Walk all bases.4450  for (const auto &I : BaseDecl->bases())4451    Flags |= ComputeVMIClassTypeInfoFlags(&I, Bases);4452 4453  return Flags;4454}4455 4456static unsigned ComputeVMIClassTypeInfoFlags(const CXXRecordDecl *RD) {4457  unsigned Flags = 0;4458  SeenBases Bases;4459 4460  // Walk all bases.4461  for (const auto &I : RD->bases())4462    Flags |= ComputeVMIClassTypeInfoFlags(&I, Bases);4463 4464  return Flags;4465}4466 4467/// BuildVMIClassTypeInfo - Build an abi::__vmi_class_type_info, used for4468/// classes with bases that do not satisfy the abi::__si_class_type_info4469/// constraints, according ti the Itanium C++ ABI, 2.9.5p5c.4470void ItaniumRTTIBuilder::BuildVMIClassTypeInfo(const CXXRecordDecl *RD) {4471  llvm::Type *UnsignedIntLTy =4472    CGM.getTypes().ConvertType(CGM.getContext().UnsignedIntTy);4473 4474  // Itanium C++ ABI 2.9.5p6c:4475  //   __flags is a word with flags describing details about the class4476  //   structure, which may be referenced by using the __flags_masks4477  //   enumeration. These flags refer to both direct and indirect bases.4478  unsigned Flags = ComputeVMIClassTypeInfoFlags(RD);4479  Fields.push_back(llvm::ConstantInt::get(UnsignedIntLTy, Flags));4480 4481  // Itanium C++ ABI 2.9.5p6c:4482  //   __base_count is a word with the number of direct proper base class4483  //   descriptions that follow.4484  Fields.push_back(llvm::ConstantInt::get(UnsignedIntLTy, RD->getNumBases()));4485 4486  if (!RD->getNumBases())4487    return;4488 4489  // Now add the base class descriptions.4490 4491  // Itanium C++ ABI 2.9.5p6c:4492  //   __base_info[] is an array of base class descriptions -- one for every4493  //   direct proper base. Each description is of the type:4494  //4495  //   struct abi::__base_class_type_info {4496  //   public:4497  //     const __class_type_info *__base_type;4498  //     long __offset_flags;4499  //4500  //     enum __offset_flags_masks {4501  //       __virtual_mask = 0x1,4502  //       __public_mask = 0x2,4503  //       __offset_shift = 84504  //     };4505  //   };4506 4507  // If we're in mingw and 'long' isn't wide enough for a pointer, use 'long4508  // long' instead of 'long' for __offset_flags. libstdc++abi uses long long on4509  // LLP64 platforms.4510  // FIXME: Consider updating libc++abi to match, and extend this logic to all4511  // LLP64 platforms.4512  QualType OffsetFlagsTy = CGM.getContext().LongTy;4513  const TargetInfo &TI = CGM.getContext().getTargetInfo();4514  if (TI.getTriple().isOSCygMing() &&4515      TI.getPointerWidth(LangAS::Default) > TI.getLongWidth())4516    OffsetFlagsTy = CGM.getContext().LongLongTy;4517  llvm::Type *OffsetFlagsLTy =4518      CGM.getTypes().ConvertType(OffsetFlagsTy);4519 4520  for (const auto &Base : RD->bases()) {4521    // The __base_type member points to the RTTI for the base type.4522    Fields.push_back(ItaniumRTTIBuilder(CXXABI).BuildTypeInfo(Base.getType()));4523 4524    auto *BaseDecl = Base.getType()->castAsCXXRecordDecl();4525    int64_t OffsetFlags = 0;4526 4527    // All but the lower 8 bits of __offset_flags are a signed offset.4528    // For a non-virtual base, this is the offset in the object of the base4529    // subobject. For a virtual base, this is the offset in the virtual table of4530    // the virtual base offset for the virtual base referenced (negative).4531    CharUnits Offset;4532    if (Base.isVirtual())4533      Offset =4534        CGM.getItaniumVTableContext().getVirtualBaseOffsetOffset(RD, BaseDecl);4535    else {4536      const ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(RD);4537      Offset = Layout.getBaseClassOffset(BaseDecl);4538    };4539 4540    OffsetFlags = uint64_t(Offset.getQuantity()) << 8;4541 4542    // The low-order byte of __offset_flags contains flags, as given by the4543    // masks from the enumeration __offset_flags_masks.4544    if (Base.isVirtual())4545      OffsetFlags |= BCTI_Virtual;4546    if (Base.getAccessSpecifier() == AS_public)4547      OffsetFlags |= BCTI_Public;4548 4549    Fields.push_back(llvm::ConstantInt::get(OffsetFlagsLTy, OffsetFlags));4550  }4551}4552 4553/// Compute the flags for a __pbase_type_info, and remove the corresponding4554/// pieces from \p Type.4555static unsigned extractPBaseFlags(ASTContext &Ctx, QualType &Type) {4556  unsigned Flags = 0;4557 4558  if (Type.isConstQualified())4559    Flags |= ItaniumRTTIBuilder::PTI_Const;4560  if (Type.isVolatileQualified())4561    Flags |= ItaniumRTTIBuilder::PTI_Volatile;4562  if (Type.isRestrictQualified())4563    Flags |= ItaniumRTTIBuilder::PTI_Restrict;4564  Type = Type.getUnqualifiedType();4565 4566  // Itanium C++ ABI 2.9.5p7:4567  //   When the abi::__pbase_type_info is for a direct or indirect pointer to an4568  //   incomplete class type, the incomplete target type flag is set.4569  if (ContainsIncompleteClassType(Type))4570    Flags |= ItaniumRTTIBuilder::PTI_Incomplete;4571 4572  if (auto *Proto = Type->getAs<FunctionProtoType>()) {4573    if (Proto->isNothrow()) {4574      Flags |= ItaniumRTTIBuilder::PTI_Noexcept;4575      Type = Ctx.getFunctionTypeWithExceptionSpec(Type, EST_None);4576    }4577  }4578 4579  return Flags;4580}4581 4582/// BuildPointerTypeInfo - Build an abi::__pointer_type_info struct,4583/// used for pointer types.4584void ItaniumRTTIBuilder::BuildPointerTypeInfo(QualType PointeeTy) {4585  // Itanium C++ ABI 2.9.5p7:4586  //   __flags is a flag word describing the cv-qualification and other4587  //   attributes of the type pointed to4588  unsigned Flags = extractPBaseFlags(CGM.getContext(), PointeeTy);4589 4590  llvm::Type *UnsignedIntLTy =4591    CGM.getTypes().ConvertType(CGM.getContext().UnsignedIntTy);4592  Fields.push_back(llvm::ConstantInt::get(UnsignedIntLTy, Flags));4593 4594  // Itanium C++ ABI 2.9.5p7:4595  //  __pointee is a pointer to the std::type_info derivation for the4596  //  unqualified type being pointed to.4597  llvm::Constant *PointeeTypeInfo =4598      ItaniumRTTIBuilder(CXXABI).BuildTypeInfo(PointeeTy);4599  Fields.push_back(PointeeTypeInfo);4600}4601 4602/// BuildPointerToMemberTypeInfo - Build an abi::__pointer_to_member_type_info4603/// struct, used for member pointer types.4604void4605ItaniumRTTIBuilder::BuildPointerToMemberTypeInfo(const MemberPointerType *Ty) {4606  QualType PointeeTy = Ty->getPointeeType();4607 4608  // Itanium C++ ABI 2.9.5p7:4609  //   __flags is a flag word describing the cv-qualification and other4610  //   attributes of the type pointed to.4611  unsigned Flags = extractPBaseFlags(CGM.getContext(), PointeeTy);4612 4613  const auto *RD = Ty->getMostRecentCXXRecordDecl();4614  if (!RD->hasDefinition())4615    Flags |= PTI_ContainingClassIncomplete;4616 4617  llvm::Type *UnsignedIntLTy =4618    CGM.getTypes().ConvertType(CGM.getContext().UnsignedIntTy);4619  Fields.push_back(llvm::ConstantInt::get(UnsignedIntLTy, Flags));4620 4621  // Itanium C++ ABI 2.9.5p7:4622  //   __pointee is a pointer to the std::type_info derivation for the4623  //   unqualified type being pointed to.4624  llvm::Constant *PointeeTypeInfo =4625      ItaniumRTTIBuilder(CXXABI).BuildTypeInfo(PointeeTy);4626  Fields.push_back(PointeeTypeInfo);4627 4628  // Itanium C++ ABI 2.9.5p9:4629  //   __context is a pointer to an abi::__class_type_info corresponding to the4630  //   class type containing the member pointed to4631  //   (e.g., the "A" in "int A::*").4632  CanQualType T = CGM.getContext().getCanonicalTagType(RD);4633  Fields.push_back(ItaniumRTTIBuilder(CXXABI).BuildTypeInfo(T));4634}4635 4636llvm::Constant *ItaniumCXXABI::getAddrOfRTTIDescriptor(QualType Ty) {4637  return ItaniumRTTIBuilder(*this).BuildTypeInfo(Ty);4638}4639 4640void ItaniumCXXABI::EmitFundamentalRTTIDescriptors(const CXXRecordDecl *RD) {4641  // Types added here must also be added to TypeInfoIsInStandardLibrary.4642  QualType FundamentalTypes[] = {4643      getContext().VoidTy,             getContext().NullPtrTy,4644      getContext().BoolTy,             getContext().WCharTy,4645      getContext().CharTy,             getContext().UnsignedCharTy,4646      getContext().SignedCharTy,       getContext().ShortTy,4647      getContext().UnsignedShortTy,    getContext().IntTy,4648      getContext().UnsignedIntTy,      getContext().LongTy,4649      getContext().UnsignedLongTy,     getContext().LongLongTy,4650      getContext().UnsignedLongLongTy, getContext().Int128Ty,4651      getContext().UnsignedInt128Ty,   getContext().HalfTy,4652      getContext().FloatTy,            getContext().DoubleTy,4653      getContext().LongDoubleTy,       getContext().Float128Ty,4654      getContext().Char8Ty,            getContext().Char16Ty,4655      getContext().Char32Ty4656  };4657  llvm::GlobalValue::DLLStorageClassTypes DLLStorageClass =4658      RD->hasAttr<DLLExportAttr>() || CGM.shouldMapVisibilityToDLLExport(RD)4659          ? llvm::GlobalValue::DLLExportStorageClass4660          : llvm::GlobalValue::DefaultStorageClass;4661  llvm::GlobalValue::VisibilityTypes Visibility =4662      CodeGenModule::GetLLVMVisibility(RD->getVisibility());4663  for (const QualType &FundamentalType : FundamentalTypes) {4664    QualType PointerType = getContext().getPointerType(FundamentalType);4665    QualType PointerTypeConst = getContext().getPointerType(4666        FundamentalType.withConst());4667    for (QualType Type : {FundamentalType, PointerType, PointerTypeConst})4668      ItaniumRTTIBuilder(*this).BuildTypeInfo(4669          Type, llvm::GlobalValue::ExternalLinkage,4670          Visibility, DLLStorageClass);4671  }4672}4673 4674/// What sort of uniqueness rules should we use for the RTTI for the4675/// given type?4676ItaniumCXXABI::RTTIUniquenessKind ItaniumCXXABI::classifyRTTIUniqueness(4677    QualType CanTy, llvm::GlobalValue::LinkageTypes Linkage) const {4678  if (shouldRTTIBeUnique())4679    return RUK_Unique;4680 4681  // It's only necessary for linkonce_odr or weak_odr linkage.4682  if (Linkage != llvm::GlobalValue::LinkOnceODRLinkage &&4683      Linkage != llvm::GlobalValue::WeakODRLinkage)4684    return RUK_Unique;4685 4686  // It's only necessary with default visibility.4687  if (CanTy->getVisibility() != DefaultVisibility)4688    return RUK_Unique;4689 4690  // If we're not required to publish this symbol, hide it.4691  if (Linkage == llvm::GlobalValue::LinkOnceODRLinkage)4692    return RUK_NonUniqueHidden;4693 4694  // If we're required to publish this symbol, as we might be under an4695  // explicit instantiation, leave it with default visibility but4696  // enable string-comparisons.4697  assert(Linkage == llvm::GlobalValue::WeakODRLinkage);4698  return RUK_NonUniqueVisible;4699}4700 4701// Find out how to codegen the complete destructor and constructor4702namespace {4703enum class StructorCodegen { Emit, RAUW, Alias, COMDAT };4704}4705static StructorCodegen getCodegenToUse(CodeGenModule &CGM,4706                                       const CXXMethodDecl *MD) {4707  if (!CGM.getCodeGenOpts().CXXCtorDtorAliases)4708    return StructorCodegen::Emit;4709 4710  // The complete and base structors are not equivalent if there are any virtual4711  // bases, so emit separate functions.4712  if (MD->getParent()->getNumVBases())4713    return StructorCodegen::Emit;4714 4715  GlobalDecl AliasDecl;4716  if (const auto *DD = dyn_cast<CXXDestructorDecl>(MD)) {4717    AliasDecl = GlobalDecl(DD, Dtor_Complete);4718  } else {4719    const auto *CD = cast<CXXConstructorDecl>(MD);4720    AliasDecl = GlobalDecl(CD, Ctor_Complete);4721  }4722  llvm::GlobalValue::LinkageTypes Linkage = CGM.getFunctionLinkage(AliasDecl);4723 4724  if (llvm::GlobalValue::isDiscardableIfUnused(Linkage))4725    return StructorCodegen::RAUW;4726 4727  // FIXME: Should we allow available_externally aliases?4728  if (!llvm::GlobalAlias::isValidLinkage(Linkage))4729    return StructorCodegen::RAUW;4730 4731  if (llvm::GlobalValue::isWeakForLinker(Linkage)) {4732    // Only ELF and wasm support COMDATs with arbitrary names (C5/D5).4733    if (CGM.getTarget().getTriple().isOSBinFormatELF() ||4734        CGM.getTarget().getTriple().isOSBinFormatWasm())4735      return StructorCodegen::COMDAT;4736    return StructorCodegen::Emit;4737  }4738 4739  return StructorCodegen::Alias;4740}4741 4742static void emitConstructorDestructorAlias(CodeGenModule &CGM,4743                                           GlobalDecl AliasDecl,4744                                           GlobalDecl TargetDecl) {4745  llvm::GlobalValue::LinkageTypes Linkage = CGM.getFunctionLinkage(AliasDecl);4746 4747  StringRef MangledName = CGM.getMangledName(AliasDecl);4748  llvm::GlobalValue *Entry = CGM.GetGlobalValue(MangledName);4749  if (Entry && !Entry->isDeclaration())4750    return;4751 4752  auto *Aliasee = cast<llvm::GlobalValue>(CGM.GetAddrOfGlobal(TargetDecl));4753 4754  // Create the alias with no name.4755  auto *Alias = llvm::GlobalAlias::create(Linkage, "", Aliasee);4756 4757  // Constructors and destructors are always unnamed_addr.4758  Alias->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);4759 4760  // Switch any previous uses to the alias.4761  if (Entry) {4762    assert(Entry->getType() == Aliasee->getType() &&4763           "declaration exists with different type");4764    Alias->takeName(Entry);4765    Entry->replaceAllUsesWith(Alias);4766    Entry->eraseFromParent();4767  } else {4768    Alias->setName(MangledName);4769  }4770 4771  // Finally, set up the alias with its proper name and attributes.4772  CGM.SetCommonAttributes(AliasDecl, Alias);4773}4774 4775void ItaniumCXXABI::emitCXXStructor(GlobalDecl GD) {4776  auto *MD = cast<CXXMethodDecl>(GD.getDecl());4777  auto *CD = dyn_cast<CXXConstructorDecl>(MD);4778  const CXXDestructorDecl *DD = CD ? nullptr : cast<CXXDestructorDecl>(MD);4779 4780  StructorCodegen CGType = getCodegenToUse(CGM, MD);4781 4782  if (CD ? GD.getCtorType() == Ctor_Complete4783         : GD.getDtorType() == Dtor_Complete) {4784    GlobalDecl BaseDecl;4785    if (CD)4786      BaseDecl = GD.getWithCtorType(Ctor_Base);4787    else4788      BaseDecl = GD.getWithDtorType(Dtor_Base);4789 4790    if (CGType == StructorCodegen::Alias || CGType == StructorCodegen::COMDAT) {4791      emitConstructorDestructorAlias(CGM, GD, BaseDecl);4792      return;4793    }4794 4795    if (CGType == StructorCodegen::RAUW) {4796      StringRef MangledName = CGM.getMangledName(GD);4797      auto *Aliasee = CGM.GetAddrOfGlobal(BaseDecl);4798      CGM.addReplacement(MangledName, Aliasee);4799      return;4800    }4801  }4802 4803  // The base destructor is equivalent to the base destructor of its4804  // base class if there is exactly one non-virtual base class with a4805  // non-trivial destructor, there are no fields with a non-trivial4806  // destructor, and the body of the destructor is trivial.4807  if (DD && GD.getDtorType() == Dtor_Base &&4808      CGType != StructorCodegen::COMDAT &&4809      !CGM.TryEmitBaseDestructorAsAlias(DD))4810    return;4811 4812  // FIXME: The deleting destructor is equivalent to the selected operator4813  // delete if:4814  //  * either the delete is a destroying operator delete or the destructor4815  //    would be trivial if it weren't virtual,4816  //  * the conversion from the 'this' parameter to the first parameter of the4817  //    destructor is equivalent to a bitcast,4818  //  * the destructor does not have an implicit "this" return, and4819  //  * the operator delete has the same calling convention and IR function type4820  //    as the destructor.4821  // In such cases we should try to emit the deleting dtor as an alias to the4822  // selected 'operator delete'.4823 4824  llvm::Function *Fn = CGM.codegenCXXStructor(GD);4825 4826  if (CGType == StructorCodegen::COMDAT) {4827    SmallString<256> Buffer;4828    llvm::raw_svector_ostream Out(Buffer);4829    if (DD)4830      getMangleContext().mangleCXXDtorComdat(DD, Out);4831    else4832      getMangleContext().mangleCXXCtorComdat(CD, Out);4833    llvm::Comdat *C = CGM.getModule().getOrInsertComdat(Out.str());4834    Fn->setComdat(C);4835  } else {4836    CGM.maybeSetTrivialComdat(*MD, *Fn);4837  }4838}4839 4840static llvm::FunctionCallee getBeginCatchFn(CodeGenModule &CGM) {4841  // void *__cxa_begin_catch(void*);4842  llvm::FunctionType *FTy = llvm::FunctionType::get(4843      CGM.Int8PtrTy, CGM.Int8PtrTy, /*isVarArg=*/false);4844 4845  return CGM.CreateRuntimeFunction(FTy, "__cxa_begin_catch");4846}4847 4848static llvm::FunctionCallee getEndCatchFn(CodeGenModule &CGM) {4849  // void __cxa_end_catch();4850  llvm::FunctionType *FTy =4851      llvm::FunctionType::get(CGM.VoidTy, /*isVarArg=*/false);4852 4853  return CGM.CreateRuntimeFunction(FTy, "__cxa_end_catch");4854}4855 4856static llvm::FunctionCallee getGetExceptionPtrFn(CodeGenModule &CGM) {4857  // void *__cxa_get_exception_ptr(void*);4858  llvm::FunctionType *FTy = llvm::FunctionType::get(4859      CGM.Int8PtrTy, CGM.Int8PtrTy, /*isVarArg=*/false);4860 4861  return CGM.CreateRuntimeFunction(FTy, "__cxa_get_exception_ptr");4862}4863 4864namespace {4865  /// A cleanup to call __cxa_end_catch.  In many cases, the caught4866  /// exception type lets us state definitively that the thrown exception4867  /// type does not have a destructor.  In particular:4868  ///   - Catch-alls tell us nothing, so we have to conservatively4869  ///     assume that the thrown exception might have a destructor.4870  ///   - Catches by reference behave according to their base types.4871  ///   - Catches of non-record types will only trigger for exceptions4872  ///     of non-record types, which never have destructors.4873  ///   - Catches of record types can trigger for arbitrary subclasses4874  ///     of the caught type, so we have to assume the actual thrown4875  ///     exception type might have a throwing destructor, even if the4876  ///     caught type's destructor is trivial or nothrow.4877  struct CallEndCatch final : EHScopeStack::Cleanup {4878    CallEndCatch(bool MightThrow) : MightThrow(MightThrow) {}4879    bool MightThrow;4880 4881    void Emit(CodeGenFunction &CGF, Flags flags) override {4882      if (!MightThrow) {4883        CGF.EmitNounwindRuntimeCall(getEndCatchFn(CGF.CGM));4884        return;4885      }4886 4887      CGF.EmitRuntimeCallOrInvoke(getEndCatchFn(CGF.CGM));4888    }4889  };4890}4891 4892/// Emits a call to __cxa_begin_catch and enters a cleanup to call4893/// __cxa_end_catch. If -fassume-nothrow-exception-dtor is specified, we assume4894/// that the exception object's dtor is nothrow, therefore the __cxa_end_catch4895/// call can be marked as nounwind even if EndMightThrow is true.4896///4897/// \param EndMightThrow - true if __cxa_end_catch might throw4898static llvm::Value *CallBeginCatch(CodeGenFunction &CGF,4899                                   llvm::Value *Exn,4900                                   bool EndMightThrow) {4901  llvm::CallInst *call =4902    CGF.EmitNounwindRuntimeCall(getBeginCatchFn(CGF.CGM), Exn);4903 4904  CGF.EHStack.pushCleanup<CallEndCatch>(4905      NormalAndEHCleanup,4906      EndMightThrow && !CGF.CGM.getLangOpts().AssumeNothrowExceptionDtor);4907 4908  return call;4909}4910 4911/// A "special initializer" callback for initializing a catch4912/// parameter during catch initialization.4913static void InitCatchParam(CodeGenFunction &CGF,4914                           const VarDecl &CatchParam,4915                           Address ParamAddr,4916                           SourceLocation Loc) {4917  // Load the exception from where the landing pad saved it.4918  llvm::Value *Exn = CGF.getExceptionFromSlot();4919 4920  CanQualType CatchType =4921    CGF.CGM.getContext().getCanonicalType(CatchParam.getType());4922  llvm::Type *LLVMCatchTy = CGF.ConvertTypeForMem(CatchType);4923 4924  // If we're catching by reference, we can just cast the object4925  // pointer to the appropriate pointer.4926  if (isa<ReferenceType>(CatchType)) {4927    QualType CaughtType = cast<ReferenceType>(CatchType)->getPointeeType();4928    bool EndCatchMightThrow = CaughtType->isRecordType();4929 4930    // __cxa_begin_catch returns the adjusted object pointer.4931    llvm::Value *AdjustedExn = CallBeginCatch(CGF, Exn, EndCatchMightThrow);4932 4933    // We have no way to tell the personality function that we're4934    // catching by reference, so if we're catching a pointer,4935    // __cxa_begin_catch will actually return that pointer by value.4936    if (const PointerType *PT = dyn_cast<PointerType>(CaughtType)) {4937      QualType PointeeType = PT->getPointeeType();4938 4939      // When catching by reference, generally we should just ignore4940      // this by-value pointer and use the exception object instead.4941      if (!PointeeType->isRecordType()) {4942 4943        // Exn points to the struct _Unwind_Exception header, which4944        // we have to skip past in order to reach the exception data.4945        unsigned HeaderSize =4946          CGF.CGM.getTargetCodeGenInfo().getSizeOfUnwindException();4947        AdjustedExn =4948            CGF.Builder.CreateConstGEP1_32(CGF.Int8Ty, Exn, HeaderSize);4949 4950      // However, if we're catching a pointer-to-record type that won't4951      // work, because the personality function might have adjusted4952      // the pointer.  There's actually no way for us to fully satisfy4953      // the language/ABI contract here:  we can't use Exn because it4954      // might have the wrong adjustment, but we can't use the by-value4955      // pointer because it's off by a level of abstraction.4956      //4957      // The current solution is to dump the adjusted pointer into an4958      // alloca, which breaks language semantics (because changing the4959      // pointer doesn't change the exception) but at least works.4960      // The better solution would be to filter out non-exact matches4961      // and rethrow them, but this is tricky because the rethrow4962      // really needs to be catchable by other sites at this landing4963      // pad.  The best solution is to fix the personality function.4964      } else {4965        // Pull the pointer for the reference type off.4966        llvm::Type *PtrTy = CGF.ConvertTypeForMem(CaughtType);4967 4968        // Create the temporary and write the adjusted pointer into it.4969        Address ExnPtrTmp =4970          CGF.CreateTempAlloca(PtrTy, CGF.getPointerAlign(), "exn.byref.tmp");4971        llvm::Value *Casted = CGF.Builder.CreateBitCast(AdjustedExn, PtrTy);4972        CGF.Builder.CreateStore(Casted, ExnPtrTmp);4973 4974        // Bind the reference to the temporary.4975        AdjustedExn = ExnPtrTmp.emitRawPointer(CGF);4976      }4977    }4978 4979    llvm::Value *ExnCast =4980      CGF.Builder.CreateBitCast(AdjustedExn, LLVMCatchTy, "exn.byref");4981    CGF.Builder.CreateStore(ExnCast, ParamAddr);4982    return;4983  }4984 4985  // Scalars and complexes.4986  TypeEvaluationKind TEK = CGF.getEvaluationKind(CatchType);4987  if (TEK != TEK_Aggregate) {4988    llvm::Value *AdjustedExn = CallBeginCatch(CGF, Exn, false);4989 4990    // If the catch type is a pointer type, __cxa_begin_catch returns4991    // the pointer by value.4992    if (CatchType->hasPointerRepresentation()) {4993      llvm::Value *CastExn =4994        CGF.Builder.CreateBitCast(AdjustedExn, LLVMCatchTy, "exn.casted");4995 4996      switch (CatchType.getQualifiers().getObjCLifetime()) {4997      case Qualifiers::OCL_Strong:4998        CastExn = CGF.EmitARCRetainNonBlock(CastExn);4999        [[fallthrough]];5000 5001      case Qualifiers::OCL_None:5002      case Qualifiers::OCL_ExplicitNone:5003      case Qualifiers::OCL_Autoreleasing:5004        CGF.Builder.CreateStore(CastExn, ParamAddr);5005        return;5006 5007      case Qualifiers::OCL_Weak:5008        CGF.EmitARCInitWeak(ParamAddr, CastExn);5009        return;5010      }5011      llvm_unreachable("bad ownership qualifier!");5012    }5013 5014    // Otherwise, it returns a pointer into the exception object.5015 5016    LValue srcLV = CGF.MakeNaturalAlignAddrLValue(AdjustedExn, CatchType);5017    LValue destLV = CGF.MakeAddrLValue(ParamAddr, CatchType);5018    switch (TEK) {5019    case TEK_Complex:5020      CGF.EmitStoreOfComplex(CGF.EmitLoadOfComplex(srcLV, Loc), destLV,5021                             /*init*/ true);5022      return;5023    case TEK_Scalar: {5024      llvm::Value *ExnLoad = CGF.EmitLoadOfScalar(srcLV, Loc);5025      CGF.EmitStoreOfScalar(ExnLoad, destLV, /*init*/ true);5026      return;5027    }5028    case TEK_Aggregate:5029      llvm_unreachable("evaluation kind filtered out!");5030    }5031    llvm_unreachable("bad evaluation kind");5032  }5033 5034  assert(isa<RecordType>(CatchType) && "unexpected catch type!");5035  auto catchRD = CatchType->getAsCXXRecordDecl();5036  CharUnits caughtExnAlignment = CGF.CGM.getClassPointerAlignment(catchRD);5037 5038  llvm::Type *PtrTy = CGF.DefaultPtrTy;5039 5040  // Check for a copy expression.  If we don't have a copy expression,5041  // that means a trivial copy is okay.5042  const Expr *copyExpr = CatchParam.getInit();5043  if (!copyExpr) {5044    llvm::Value *rawAdjustedExn = CallBeginCatch(CGF, Exn, true);5045    Address adjustedExn(CGF.Builder.CreateBitCast(rawAdjustedExn, PtrTy),5046                        LLVMCatchTy, caughtExnAlignment);5047    LValue Dest = CGF.MakeAddrLValue(ParamAddr, CatchType);5048    LValue Src = CGF.MakeAddrLValue(adjustedExn, CatchType);5049    CGF.EmitAggregateCopy(Dest, Src, CatchType, AggValueSlot::DoesNotOverlap);5050    return;5051  }5052 5053  // We have to call __cxa_get_exception_ptr to get the adjusted5054  // pointer before copying.5055  llvm::CallInst *rawAdjustedExn =5056    CGF.EmitNounwindRuntimeCall(getGetExceptionPtrFn(CGF.CGM), Exn);5057 5058  // Cast that to the appropriate type.5059  Address adjustedExn(CGF.Builder.CreateBitCast(rawAdjustedExn, PtrTy),5060                      LLVMCatchTy, caughtExnAlignment);5061 5062  // The copy expression is defined in terms of an OpaqueValueExpr.5063  // Find it and map it to the adjusted expression.5064  CodeGenFunction::OpaqueValueMapping5065    opaque(CGF, OpaqueValueExpr::findInCopyConstruct(copyExpr),5066           CGF.MakeAddrLValue(adjustedExn, CatchParam.getType()));5067 5068  // Call the copy ctor in a terminate scope.5069  CGF.EHStack.pushTerminate();5070 5071  // Perform the copy construction.5072  CGF.EmitAggExpr(copyExpr,5073                  AggValueSlot::forAddr(ParamAddr, Qualifiers(),5074                                        AggValueSlot::IsNotDestructed,5075                                        AggValueSlot::DoesNotNeedGCBarriers,5076                                        AggValueSlot::IsNotAliased,5077                                        AggValueSlot::DoesNotOverlap));5078 5079  // Leave the terminate scope.5080  CGF.EHStack.popTerminate();5081 5082  // Undo the opaque value mapping.5083  opaque.pop();5084 5085  // Finally we can call __cxa_begin_catch.5086  CallBeginCatch(CGF, Exn, true);5087}5088 5089/// Begins a catch statement by initializing the catch variable and5090/// calling __cxa_begin_catch.5091void ItaniumCXXABI::emitBeginCatch(CodeGenFunction &CGF,5092                                   const CXXCatchStmt *S) {5093  // We have to be very careful with the ordering of cleanups here:5094  //   C++ [except.throw]p4:5095  //     The destruction [of the exception temporary] occurs5096  //     immediately after the destruction of the object declared in5097  //     the exception-declaration in the handler.5098  //5099  // So the precise ordering is:5100  //   1.  Construct catch variable.5101  //   2.  __cxa_begin_catch5102  //   3.  Enter __cxa_end_catch cleanup5103  //   4.  Enter dtor cleanup5104  //5105  // We do this by using a slightly abnormal initialization process.5106  // Delegation sequence:5107  //   - ExitCXXTryStmt opens a RunCleanupsScope5108  //     - EmitAutoVarAlloca creates the variable and debug info5109  //       - InitCatchParam initializes the variable from the exception5110  //       - CallBeginCatch calls __cxa_begin_catch5111  //       - CallBeginCatch enters the __cxa_end_catch cleanup5112  //     - EmitAutoVarCleanups enters the variable destructor cleanup5113  //   - EmitCXXTryStmt emits the code for the catch body5114  //   - EmitCXXTryStmt close the RunCleanupsScope5115 5116  VarDecl *CatchParam = S->getExceptionDecl();5117  if (!CatchParam) {5118    llvm::Value *Exn = CGF.getExceptionFromSlot();5119    CallBeginCatch(CGF, Exn, true);5120    return;5121  }5122 5123  // Emit the local.5124  CodeGenFunction::AutoVarEmission var = CGF.EmitAutoVarAlloca(*CatchParam);5125  {5126    ApplyAtomGroup Grp(CGF.getDebugInfo());5127    InitCatchParam(CGF, *CatchParam, var.getObjectAddress(CGF),5128                   S->getBeginLoc());5129  }5130  CGF.EmitAutoVarCleanups(var);5131}5132 5133/// Get or define the following function:5134///   void @__clang_call_terminate(i8* %exn) nounwind noreturn5135/// This code is used only in C++.5136static llvm::FunctionCallee getClangCallTerminateFn(CodeGenModule &CGM) {5137  ASTContext &C = CGM.getContext();5138  const CGFunctionInfo &FI = CGM.getTypes().arrangeBuiltinFunctionDeclaration(5139      C.VoidTy, {C.getPointerType(C.CharTy)});5140  llvm::FunctionType *fnTy = CGM.getTypes().GetFunctionType(FI);5141  llvm::FunctionCallee fnRef = CGM.CreateRuntimeFunction(5142      fnTy, "__clang_call_terminate", llvm::AttributeList(), /*Local=*/true);5143  llvm::Function *fn =5144      cast<llvm::Function>(fnRef.getCallee()->stripPointerCasts());5145  if (fn->empty()) {5146    CGM.SetLLVMFunctionAttributes(GlobalDecl(), FI, fn, /*IsThunk=*/false);5147    CGM.SetLLVMFunctionAttributesForDefinition(nullptr, fn);5148    fn->setDoesNotThrow();5149    fn->setDoesNotReturn();5150 5151    // What we really want is to massively penalize inlining without5152    // forbidding it completely.  The difference between that and5153    // 'noinline' is negligible.5154    fn->addFnAttr(llvm::Attribute::NoInline);5155 5156    // Allow this function to be shared across translation units, but5157    // we don't want it to turn into an exported symbol.5158    fn->setLinkage(llvm::Function::LinkOnceODRLinkage);5159    fn->setVisibility(llvm::Function::HiddenVisibility);5160    if (CGM.supportsCOMDAT())5161      fn->setComdat(CGM.getModule().getOrInsertComdat(fn->getName()));5162 5163    // Set up the function.5164    llvm::BasicBlock *entry =5165        llvm::BasicBlock::Create(CGM.getLLVMContext(), "", fn);5166    CGBuilderTy builder(CGM, entry);5167 5168    // Pull the exception pointer out of the parameter list.5169    llvm::Value *exn = &*fn->arg_begin();5170 5171    // Call __cxa_begin_catch(exn).5172    llvm::CallInst *catchCall = builder.CreateCall(getBeginCatchFn(CGM), exn);5173    catchCall->setDoesNotThrow();5174    catchCall->setCallingConv(CGM.getRuntimeCC());5175 5176    // Call std::terminate().5177    llvm::CallInst *termCall = builder.CreateCall(CGM.getTerminateFn());5178    termCall->setDoesNotThrow();5179    termCall->setDoesNotReturn();5180    termCall->setCallingConv(CGM.getRuntimeCC());5181 5182    // std::terminate cannot return.5183    builder.CreateUnreachable();5184  }5185  return fnRef;5186}5187 5188llvm::CallInst *5189ItaniumCXXABI::emitTerminateForUnexpectedException(CodeGenFunction &CGF,5190                                                   llvm::Value *Exn) {5191  // In C++, we want to call __cxa_begin_catch() before terminating.5192  if (Exn) {5193    assert(CGF.CGM.getLangOpts().CPlusPlus);5194    return CGF.EmitNounwindRuntimeCall(getClangCallTerminateFn(CGF.CGM), Exn);5195  }5196  return CGF.EmitNounwindRuntimeCall(CGF.CGM.getTerminateFn());5197}5198 5199std::pair<llvm::Value *, const CXXRecordDecl *>5200ItaniumCXXABI::LoadVTablePtr(CodeGenFunction &CGF, Address This,5201                             const CXXRecordDecl *RD) {5202  return {CGF.GetVTablePtr(This, CGM.Int8PtrTy, RD), RD};5203}5204 5205llvm::Constant *5206ItaniumCXXABI::getSignedVirtualMemberFunctionPointer(const CXXMethodDecl *MD) {5207  const CXXMethodDecl *origMD =5208      cast<CXXMethodDecl>(CGM.getItaniumVTableContext()5209                              .findOriginalMethod(MD->getCanonicalDecl())5210                              .getDecl());5211  llvm::Constant *thunk = getOrCreateVirtualFunctionPointerThunk(origMD);5212  QualType funcType = CGM.getContext().getMemberPointerType(5213      MD->getType(), /*Qualifier=*/std::nullopt, MD->getParent());5214  return CGM.getMemberFunctionPointer(thunk, funcType);5215}5216 5217void WebAssemblyCXXABI::emitBeginCatch(CodeGenFunction &CGF,5218                                       const CXXCatchStmt *C) {5219  if (CGF.getTarget().hasFeature("exception-handling"))5220    CGF.EHStack.pushCleanup<CatchRetScope>(5221        NormalCleanup, cast<llvm::CatchPadInst>(CGF.CurrentFuncletPad));5222  ItaniumCXXABI::emitBeginCatch(CGF, C);5223}5224 5225llvm::CallInst *5226WebAssemblyCXXABI::emitTerminateForUnexpectedException(CodeGenFunction &CGF,5227                                                       llvm::Value *Exn) {5228  // Itanium ABI calls __clang_call_terminate(), which __cxa_begin_catch() on5229  // the violating exception to mark it handled, but it is currently hard to do5230  // with wasm EH instruction structure with catch/catch_all, we just call5231  // std::terminate and ignore the violating exception as in CGCXXABI in Wasm EH5232  // and call __clang_call_terminate only in Emscripten EH.5233  // TODO Consider code transformation that makes calling __clang_call_terminate5234  // in Wasm EH possible.5235  if (Exn && !EHPersonality::get(CGF).isWasmPersonality()) {5236    assert(CGF.CGM.getLangOpts().CPlusPlus);5237    return CGF.EmitNounwindRuntimeCall(getClangCallTerminateFn(CGF.CGM), Exn);5238  }5239  return CGCXXABI::emitTerminateForUnexpectedException(CGF, Exn);5240}5241 5242/// Register a global destructor as best as we know how.5243void XLCXXABI::registerGlobalDtor(CodeGenFunction &CGF, const VarDecl &D,5244                                  llvm::FunctionCallee Dtor,5245                                  llvm::Constant *Addr) {5246  if (D.getTLSKind() != VarDecl::TLS_None) {5247    llvm::PointerType *PtrTy = CGF.DefaultPtrTy;5248 5249    // extern "C" int __pt_atexit_np(int flags, int(*)(int,...), ...);5250    llvm::FunctionType *AtExitTy =5251        llvm::FunctionType::get(CGM.IntTy, {CGM.IntTy, PtrTy}, true);5252 5253    // Fetch the actual function.5254    llvm::FunctionCallee AtExit =5255        CGM.CreateRuntimeFunction(AtExitTy, "__pt_atexit_np");5256 5257    // Create __dtor function for the var decl.5258    llvm::Function *DtorStub = CGF.createTLSAtExitStub(D, Dtor, Addr, AtExit);5259 5260    // Register above __dtor with atexit().5261    // First param is flags and must be 0, second param is function ptr5262    llvm::Value *NV = llvm::Constant::getNullValue(CGM.IntTy);5263    CGF.EmitNounwindRuntimeCall(AtExit, {NV, DtorStub});5264 5265    // Cannot unregister TLS __dtor so done5266    return;5267  }5268 5269  // Create __dtor function for the var decl.5270  llvm::Function *DtorStub =5271      cast<llvm::Function>(CGF.createAtExitStub(D, Dtor, Addr));5272 5273  // Register above __dtor with atexit().5274  CGF.registerGlobalDtorWithAtExit(DtorStub);5275 5276  // Emit __finalize function to unregister __dtor and (as appropriate) call5277  // __dtor.5278  emitCXXStermFinalizer(D, DtorStub, Addr);5279}5280 5281void XLCXXABI::emitCXXStermFinalizer(const VarDecl &D, llvm::Function *dtorStub,5282                                     llvm::Constant *addr) {5283  llvm::FunctionType *FTy = llvm::FunctionType::get(CGM.VoidTy, false);5284  SmallString<256> FnName;5285  {5286    llvm::raw_svector_ostream Out(FnName);5287    getMangleContext().mangleDynamicStermFinalizer(&D, Out);5288  }5289 5290  // Create the finalization action associated with a variable.5291  const CGFunctionInfo &FI = CGM.getTypes().arrangeNullaryFunction();5292  llvm::Function *StermFinalizer = CGM.CreateGlobalInitOrCleanUpFunction(5293      FTy, FnName.str(), FI, D.getLocation());5294 5295  CodeGenFunction CGF(CGM);5296 5297  CGF.StartFunction(GlobalDecl(), CGM.getContext().VoidTy, StermFinalizer, FI,5298                    FunctionArgList(), D.getLocation(),5299                    D.getInit()->getExprLoc());5300 5301  // The unatexit subroutine unregisters __dtor functions that were previously5302  // registered by the atexit subroutine. If the referenced function is found,5303  // the unatexit returns a value of 0, meaning that the cleanup is still5304  // pending (and we should call the __dtor function).5305  llvm::Value *V = CGF.unregisterGlobalDtorWithUnAtExit(dtorStub);5306 5307  llvm::Value *NeedsDestruct = CGF.Builder.CreateIsNull(V, "needs_destruct");5308 5309  llvm::BasicBlock *DestructCallBlock = CGF.createBasicBlock("destruct.call");5310  llvm::BasicBlock *EndBlock = CGF.createBasicBlock("destruct.end");5311 5312  // Check if unatexit returns a value of 0. If it does, jump to5313  // DestructCallBlock, otherwise jump to EndBlock directly.5314  CGF.Builder.CreateCondBr(NeedsDestruct, DestructCallBlock, EndBlock);5315 5316  CGF.EmitBlock(DestructCallBlock);5317 5318  // Emit the call to dtorStub.5319  llvm::CallInst *CI = CGF.Builder.CreateCall(dtorStub);5320 5321  // Make sure the call and the callee agree on calling convention.5322  CI->setCallingConv(dtorStub->getCallingConv());5323 5324  CGF.EmitBlock(EndBlock);5325 5326  CGF.FinishFunction();5327 5328  if (auto *IPA = D.getAttr<InitPriorityAttr>()) {5329    CGM.AddCXXPrioritizedStermFinalizerEntry(StermFinalizer,5330                                             IPA->getPriority());5331  } else if (isTemplateInstantiation(D.getTemplateSpecializationKind()) ||5332             getContext().GetGVALinkageForVariable(&D) == GVA_DiscardableODR) {5333    // According to C++ [basic.start.init]p2, class template static data5334    // members (i.e., implicitly or explicitly instantiated specializations)5335    // have unordered initialization. As a consequence, we can put them into5336    // their own llvm.global_dtors entry.5337    CGM.AddCXXStermFinalizerToGlobalDtor(StermFinalizer, 65535);5338  } else {5339    CGM.AddCXXStermFinalizerEntry(StermFinalizer);5340  }5341}5342