//===----- CGCXXABI.h - Interface to C++ ABIs -------------------*- C++ -*-===//

//

// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.

// See https://llvm.org/LICENSE.txt for license information.

// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

//

//===----------------------------------------------------------------------===//

//

// This provides an abstract class for C++ code generation. Concrete subclasses

// of this implement code generation for specific C++ ABIs.

//

//===----------------------------------------------------------------------===//

#ifndef LLVM_CLANG_LIB_CODEGEN_CGCXXABI_H

#define LLVM_CLANG_LIB_CODEGEN_CGCXXABI_H

#include "CodeGenFunction.h"

#include "clang/Basic/LLVM.h"

#include "clang/CodeGen/CodeGenABITypes.h"

namespace llvm {

class Constant;

class Type;

class Value;

class CallInst;

}

namespace clang {

class CastExpr;

class CXXConstructorDecl;

class CXXDestructorDecl;

class CXXMethodDecl;

class CXXRecordDecl;

class FieldDecl;

class MangleContext;

namespace CodeGen {

class CGCallee;

class CodeGenFunction;

class CodeGenModule;

struct CatchTypeInfo;

/// Implements C++ ABI-specific code generation functions.

class CGCXXABI {

protected:

  CodeGenModule &CGM;

  std::unique_ptr<MangleContext> MangleCtx;

  CGCXXABI(CodeGenModule &CGM)

    : CGM(CGM), MangleCtx(CGM.getContext().createMangleContext()) {}

protected:

  ImplicitParamDecl *getThisDecl(CodeGenFunction &CGF) {

    return CGF.CXXABIThisDecl;

  }

  llvm::Value *getThisValue(CodeGenFunction &CGF) {

    return CGF.CXXABIThisValue;

  }

  Address getThisAddress(CodeGenFunction &CGF) {

    return Address(CGF.CXXABIThisValue, CGF.CXXABIThisAlignment);

  }

  /// Issue a diagnostic about unsupported features in the ABI.

  void ErrorUnsupportedABI(CodeGenFunction &CGF, StringRef S);

  /// Get a null value for unsupported member pointers.

  llvm::Constant *GetBogusMemberPointer(QualType T);

  ImplicitParamDecl *&getStructorImplicitParamDecl(CodeGenFunction &CGF) {

    return CGF.CXXStructorImplicitParamDecl;

  }

  llvm::Value *&getStructorImplicitParamValue(CodeGenFunction &CGF) {

    return CGF.CXXStructorImplicitParamValue;

  }

  /// Loads the incoming C++ this pointer as it was passed by the caller.

  llvm::Value *loadIncomingCXXThis(CodeGenFunction &CGF);

  void setCXXABIThisValue(CodeGenFunction &CGF, llvm::Value *ThisPtr);

  ASTContext &getContext() const { return CGM.getContext(); }

  virtual bool requiresArrayCookie(const CXXDeleteExpr *E, QualType eltType);

  virtual bool requiresArrayCookie(const CXXNewExpr *E);

  /// Determine whether there's something special about the rules of

  /// the ABI tell us that 'this' is a complete object within the

  /// given function.  Obvious common logic like being defined on a

  /// final class will have been taken care of by the caller.

  virtual bool isThisCompleteObject(GlobalDecl GD) const = 0;

public:

  virtual ~CGCXXABI();

  /// Gets the mangle context.

  MangleContext &getMangleContext() {

    return *MangleCtx;

  }

  /// Returns true if the given constructor or destructor is one of the

  /// kinds that the ABI says returns 'this' (only applies when called

  /// non-virtually for destructors).

  ///

  /// There currently is no way to indicate if a destructor returns 'this'

  /// when called virtually, and code generation does not support the case.

  virtual bool HasThisReturn(GlobalDecl GD) const { return false; }

  virtual bool hasMostDerivedReturn(GlobalDecl GD) const { return false; }

  virtual bool useSinitAndSterm() const { return false; }

  /// Returns true if the target allows calling a function through a pointer

  /// with a different signature than the actual function (or equivalently,

  /// bitcasting a function or function pointer to a different function type).

  /// In principle in the most general case this could depend on the target, the

  /// calling convention, and the actual types of the arguments and return

  /// value. Here it just means whether the signature mismatch could *ever* be

  /// allowed; in other words, does the target do strict checking of signatures

  /// for all calls.

  virtual bool canCallMismatchedFunctionType() const { return true; }

  /// If the C++ ABI requires the given type be returned in a particular way,

  /// this method sets RetAI and returns true.

  virtual bool classifyReturnType(CGFunctionInfo &FI) const = 0;

  /// Specify how one should pass an argument of a record type.

  enum RecordArgABI {

    /// Pass it using the normal C aggregate rules for the ABI, potentially

    /// introducing extra copies and passing some or all of it in registers.

    RAA_Default = 0,

    /// Pass it on the stack using its defined layout.  The argument must be

    /// evaluated directly into the correct stack position in the arguments area,

    /// and the call machinery must not move it or introduce extra copies.

    RAA_DirectInMemory,

    /// Pass it as a pointer to temporary memory.

    RAA_Indirect

  };

  /// Returns how an argument of the given record type should be passed.

  virtual RecordArgABI getRecordArgABI(const CXXRecordDecl *RD) const = 0;

  /// Returns true if the implicit 'sret' parameter comes after the implicit

  /// 'this' parameter of C++ instance methods.

  virtual bool isSRetParameterAfterThis() const { return false; }

  /// Find the LLVM type used to represent the given member pointer

  /// type.

  virtual llvm::Type *

  ConvertMemberPointerType(const MemberPointerType *MPT);

  /// Load a member function from an object and a member function

  /// pointer.  Apply the this-adjustment and set 'This' to the

  /// adjusted value.

  virtual CGCallee EmitLoadOfMemberFunctionPointer(

      CodeGenFunction &CGF, const Expr *E, Address This,

      llvm::Value *&ThisPtrForCall, llvm::Value *MemPtr,

      const MemberPointerType *MPT);

  /// Calculate an l-value from an object and a data member pointer.

  virtual llvm::Value *

  EmitMemberDataPointerAddress(CodeGenFunction &CGF, const Expr *E,

                               Address Base, llvm::Value *MemPtr,

                               const MemberPointerType *MPT);

  /// Perform a derived-to-base, base-to-derived, or bitcast member

  /// pointer conversion.

  virtual llvm::Value *EmitMemberPointerConversion(CodeGenFunction &CGF,

                                                   const CastExpr *E,

                                                   llvm::Value *Src);

  /// Perform a derived-to-base, base-to-derived, or bitcast member

  /// pointer conversion on a constant value.

  virtual llvm::Constant *EmitMemberPointerConversion(const CastExpr *E,

                                                      llvm::Constant *Src);

  /// Return true if the given member pointer can be zero-initialized

  /// (in the C++ sense) with an LLVM zeroinitializer.

  virtual bool isZeroInitializable(const MemberPointerType *MPT);

  /// Return whether or not a member pointers type is convertible to an IR type.

  virtual bool isMemberPointerConvertible(const MemberPointerType *MPT) const {

    return true;

  }

  /// Create a null member pointer of the given type.

  virtual llvm::Constant *EmitNullMemberPointer(const MemberPointerType *MPT);

  /// Create a member pointer for the given method.

  virtual llvm::Constant *EmitMemberFunctionPointer(const CXXMethodDecl *MD);

  /// Create a member pointer for the given field.

  virtual llvm::Constant *EmitMemberDataPointer(const MemberPointerType *MPT,

                                                CharUnits offset);

  /// Create a member pointer for the given member pointer constant.

  virtual llvm::Constant *EmitMemberPointer(const APValue &MP, QualType MPT);

  /// Emit a comparison between two member pointers.  Returns an i1.

  virtual llvm::Value *

  EmitMemberPointerComparison(CodeGenFunction &CGF,

                              llvm::Value *L,

                              llvm::Value *R,

                              const MemberPointerType *MPT,

                              bool Inequality);

  /// Determine if a member pointer is non-null.  Returns an i1.

  virtual llvm::Value *

  EmitMemberPointerIsNotNull(CodeGenFunction &CGF,

                             llvm::Value *MemPtr,

                             const MemberPointerType *MPT);

protected:

  /// A utility method for computing the offset required for the given

  /// base-to-derived or derived-to-base member-pointer conversion.

  /// Does not handle virtual conversions (in case we ever fully

  /// support an ABI that allows this).  Returns null if no adjustment

  /// is required.

  llvm::Constant *getMemberPointerAdjustment(const CastExpr *E);

  /// Computes the non-virtual adjustment needed for a member pointer

  /// conversion along an inheritance path stored in an APValue.  Unlike

  /// getMemberPointerAdjustment(), the adjustment can be negative if the path

  /// is from a derived type to a base type.

  CharUnits getMemberPointerPathAdjustment(const APValue &MP);

public:

  virtual void emitVirtualObjectDelete(CodeGenFunction &CGF,

                                       const CXXDeleteExpr *DE,

                                       Address Ptr, QualType ElementType,

                                       const CXXDestructorDecl *Dtor) = 0;

  virtual void emitRethrow(CodeGenFunction &CGF, bool isNoReturn) = 0;

  virtual void emitThrow(CodeGenFunction &CGF, const CXXThrowExpr *E) = 0;

  virtual llvm::GlobalVariable *getThrowInfo(QualType T) { return nullptr; }

  /// Determine whether it's possible to emit a vtable for \p RD, even

  /// though we do not know that the vtable has been marked as used by semantic

  /// analysis.

  virtual bool canSpeculativelyEmitVTable(const CXXRecordDecl *RD) const = 0;

  virtual void emitBeginCatch(CodeGenFunction &CGF, const CXXCatchStmt *C) = 0;

  virtual llvm::CallInst *

  emitTerminateForUnexpectedException(CodeGenFunction &CGF,

                                      llvm::Value *Exn);

  virtual llvm::Constant *getAddrOfRTTIDescriptor(QualType Ty) = 0;

  virtual CatchTypeInfo

  getAddrOfCXXCatchHandlerType(QualType Ty, QualType CatchHandlerType) = 0;

  virtual CatchTypeInfo getCatchAllTypeInfo();

  virtual bool shouldTypeidBeNullChecked(bool IsDeref,

                                         QualType SrcRecordTy) = 0;

  virtual void EmitBadTypeidCall(CodeGenFunction &CGF) = 0;

  virtual llvm::Value *EmitTypeid(CodeGenFunction &CGF, QualType SrcRecordTy,

                                  Address ThisPtr,

                                  llvm::Type *StdTypeInfoPtrTy) = 0;

  virtual bool shouldDynamicCastCallBeNullChecked(bool SrcIsPtr,

                                                  QualType SrcRecordTy) = 0;

  virtual llvm::Value *

  EmitDynamicCastCall(CodeGenFunction &CGF, Address Value,

                      QualType SrcRecordTy, QualType DestTy,

                      QualType DestRecordTy, llvm::BasicBlock *CastEnd) = 0;

  virtual llvm::Value *EmitDynamicCastToVoid(CodeGenFunction &CGF,

                                             Address Value,

                                             QualType SrcRecordTy,

                                             QualType DestTy) = 0;

  virtual bool EmitBadCastCall(CodeGenFunction &CGF) = 0;

  virtual llvm::Value *GetVirtualBaseClassOffset(CodeGenFunction &CGF,

                                                 Address This,

                                                 const CXXRecordDecl *ClassDecl,

                                        const CXXRecordDecl *BaseClassDecl) = 0;

  virtual llvm::BasicBlock *EmitCtorCompleteObjectHandler(CodeGenFunction &CGF,

                                                          const CXXRecordDecl *RD);

  /// Emit the code to initialize hidden members required

  /// to handle virtual inheritance, if needed by the ABI.

  virtual void

  initializeHiddenVirtualInheritanceMembers(CodeGenFunction &CGF,

                                            const CXXRecordDecl *RD) {}

  /// Emit constructor variants required by this ABI.

  virtual void EmitCXXConstructors(const CXXConstructorDecl *D) = 0;

  /// Additional implicit arguments to add to the beginning (Prefix) and end

  /// (Suffix) of a constructor / destructor arg list.

  ///

  /// Note that Prefix should actually be inserted *after* the first existing

  /// arg; `this` arguments always come first.

  struct AddedStructorArgs {

    struct Arg {

      llvm::Value *Value;

      QualType Type;

    };

    SmallVector<Arg, 1> Prefix;

    SmallVector<Arg, 1> Suffix;

    AddedStructorArgs() = default;

    AddedStructorArgs(SmallVector<Arg, 1> P, SmallVector<Arg, 1> S)

        : Prefix(std::move(P)), Suffix(std::move(S)) {}

    static AddedStructorArgs prefix(SmallVector<Arg, 1> Args) {

      return {std::move(Args), {}};

    }

    static AddedStructorArgs suffix(SmallVector<Arg, 1> Args) {

      return {{}, std::move(Args)};

    }

  };

  /// Similar to AddedStructorArgs, but only notes the number of additional

  /// arguments.

  struct AddedStructorArgCounts {

    unsigned Prefix = 0;

    unsigned Suffix = 0;

    AddedStructorArgCounts() = default;

    AddedStructorArgCounts(unsigned P, unsigned S) : Prefix(P), Suffix(S) {}

    static AddedStructorArgCounts prefix(unsigned N) { return {N, 0}; }

    static AddedStructorArgCounts suffix(unsigned N) { return {0, N}; }

  };

  /// Build the signature of the given constructor or destructor variant by

  /// adding any required parameters.  For convenience, ArgTys has been

  /// initialized with the type of 'this'.

  virtual AddedStructorArgCounts

  buildStructorSignature(GlobalDecl GD,

                         SmallVectorImpl<CanQualType> &ArgTys) = 0;

  /// Returns true if the given destructor type should be emitted as a linkonce

  /// delegating thunk, regardless of whether the dtor is defined in this TU or

  /// not.

  virtual bool useThunkForDtorVariant(const CXXDestructorDecl *Dtor,

                                      CXXDtorType DT) const = 0;

  virtual void setCXXDestructorDLLStorage(llvm::GlobalValue *GV,

                                          const CXXDestructorDecl *Dtor,

                                          CXXDtorType DT) const;

  virtual llvm::GlobalValue::LinkageTypes

  getCXXDestructorLinkage(GVALinkage Linkage, const CXXDestructorDecl *Dtor,

                          CXXDtorType DT) const;

  /// Emit destructor variants required by this ABI.

  virtual void EmitCXXDestructors(const CXXDestructorDecl *D) = 0;

  /// Get the type of the implicit "this" parameter used by a method. May return

  /// zero if no specific type is applicable, e.g. if the ABI expects the "this"

  /// parameter to point to some artificial offset in a complete object due to

  /// vbases being reordered.

  virtual const CXXRecordDecl *

  getThisArgumentTypeForMethod(const CXXMethodDecl *MD) {

    return MD->getParent();

  }

  /// Perform ABI-specific "this" argument adjustment required prior to

  /// a call of a virtual function.

  /// The "VirtualCall" argument is true iff the call itself is virtual.

  virtual Address

  adjustThisArgumentForVirtualFunctionCall(CodeGenFunction &CGF, GlobalDecl GD,

                                           Address This, bool VirtualCall) {

    return This;

  }

  /// Build a parameter variable suitable for 'this'.

  void buildThisParam(CodeGenFunction &CGF, FunctionArgList &Params);

  /// Insert any ABI-specific implicit parameters into the parameter list for a

  /// function.  This generally involves extra data for constructors and

  /// destructors.

  ///

  /// ABIs may also choose to override the return type, which has been

  /// initialized with the type of 'this' if HasThisReturn(CGF.CurGD) is true or

  /// the formal return type of the function otherwise.

  virtual void addImplicitStructorParams(CodeGenFunction &CGF, QualType &ResTy,

                                         FunctionArgList &Params) = 0;

  /// Get the ABI-specific "this" parameter adjustment to apply in the prologue

  /// of a virtual function.

  virtual CharUnits getVirtualFunctionPrologueThisAdjustment(GlobalDecl GD) {

    return CharUnits::Zero();

  }

  /// Emit the ABI-specific prolog for the function.

  virtual void EmitInstanceFunctionProlog(CodeGenFunction &CGF) = 0;

  virtual AddedStructorArgs

  getImplicitConstructorArgs(CodeGenFunction &CGF, const CXXConstructorDecl *D,

                             CXXCtorType Type, bool ForVirtualBase,

                             bool Delegating) = 0;

  /// Add any ABI-specific implicit arguments needed to call a constructor.

  ///

  /// \return The number of arguments added at the beginning and end of the

  /// call, which is typically zero or one.

  AddedStructorArgCounts

  addImplicitConstructorArgs(CodeGenFunction &CGF, const CXXConstructorDecl *D,

                             CXXCtorType Type, bool ForVirtualBase,

                             bool Delegating, CallArgList &Args);

  /// Get the implicit (second) parameter that comes after the "this" pointer,

  /// or nullptr if there is isn't one.

  virtual llvm::Value *

  getCXXDestructorImplicitParam(CodeGenFunction &CGF,

                                const CXXDestructorDecl *DD, CXXDtorType Type,

                                bool ForVirtualBase, bool Delegating) = 0;

  /// Emit the destructor call.

  virtual void EmitDestructorCall(CodeGenFunction &CGF,

                                  const CXXDestructorDecl *DD, CXXDtorType Type,

                                  bool ForVirtualBase, bool Delegating,

                                  Address This, QualType ThisTy) = 0;

  /// Emits the VTable definitions required for the given record type.

  virtual void emitVTableDefinitions(CodeGenVTables &CGVT,

                                     const CXXRecordDecl *RD) = 0;

  /// Checks if ABI requires extra virtual offset for vtable field.

  virtual bool

  isVirtualOffsetNeededForVTableField(CodeGenFunction &CGF,

                                      CodeGenFunction::VPtr Vptr) = 0;

  /// Checks if ABI requires to initialize vptrs for given dynamic class.

  virtual bool doStructorsInitializeVPtrs(const CXXRecordDecl *VTableClass) = 0;

  /// Get the address point of the vtable for the given base subobject.

  virtual llvm::Constant *

  getVTableAddressPoint(BaseSubobject Base,

                        const CXXRecordDecl *VTableClass) = 0;

  /// Get the address point of the vtable for the given base subobject while

  /// building a constructor or a destructor.

  virtual llvm::Value *

  getVTableAddressPointInStructor(CodeGenFunction &CGF, const CXXRecordDecl *RD,

                                  BaseSubobject Base,

                                  const CXXRecordDecl *NearestVBase) = 0;

  /// Get the address point of the vtable for the given base subobject while

  /// building a constexpr.

  virtual llvm::Constant *

  getVTableAddressPointForConstExpr(BaseSubobject Base,

                                    const CXXRecordDecl *VTableClass) = 0;

  /// Get the address of the vtable for the given record decl which should be

  /// used for the vptr at the given offset in RD.

  virtual llvm::GlobalVariable *getAddrOfVTable(const CXXRecordDecl *RD,

                                                CharUnits VPtrOffset) = 0;

  /// Build a virtual function pointer in the ABI-specific way.

  virtual CGCallee getVirtualFunctionPointer(CodeGenFunction &CGF,

                                             GlobalDecl GD, Address This,

                                             llvm::Type *Ty,

                                             SourceLocation Loc) = 0;

  using DeleteOrMemberCallExpr =

      llvm::PointerUnion<const CXXDeleteExpr *, const CXXMemberCallExpr *>;

  /// Emit the ABI-specific virtual destructor call.

  virtual llvm::Value *EmitVirtualDestructorCall(CodeGenFunction &CGF,

                                                 const CXXDestructorDecl *Dtor,

                                                 CXXDtorType DtorType,

                                                 Address This,

                                                 DeleteOrMemberCallExpr E) = 0;

  virtual void adjustCallArgsForDestructorThunk(CodeGenFunction &CGF,

                                                GlobalDecl GD,

                                                CallArgList &CallArgs) {}

  /// Emit any tables needed to implement virtual inheritance.  For Itanium,

  /// this emits virtual table tables.  For the MSVC++ ABI, this emits virtual

  /// base tables.

  virtual void emitVirtualInheritanceTables(const CXXRecordDecl *RD) = 0;

  virtual bool exportThunk() = 0;

  virtual void setThunkLinkage(llvm::Function *Thunk, bool ForVTable,

                               GlobalDecl GD, bool ReturnAdjustment) = 0;

  virtual llvm::Value *performThisAdjustment(CodeGenFunction &CGF,

                                             Address This,

                                             const ThisAdjustment &TA) = 0;

  virtual llvm::Value *performReturnAdjustment(CodeGenFunction &CGF,

                                               Address Ret,

                                               const ReturnAdjustment &RA) = 0;

  virtual void EmitReturnFromThunk(CodeGenFunction &CGF,

                                   RValue RV, QualType ResultType);

  virtual size_t getSrcArgforCopyCtor(const CXXConstructorDecl *,

                                      FunctionArgList &Args) const = 0;

  /// Gets the offsets of all the virtual base pointers in a given class.

  virtual std::vector<CharUnits> getVBPtrOffsets(const CXXRecordDecl *RD);

  /// Gets the pure virtual member call function.

  virtual StringRef GetPureVirtualCallName() = 0;

  /// Gets the deleted virtual member call name.

  virtual StringRef GetDeletedVirtualCallName() = 0;

  /**************************** Array cookies ******************************/

  /// Returns the extra size required in order to store the array

  /// cookie for the given new-expression.  May return 0 to indicate that no

  /// array cookie is required.

  ///

  /// Several cases are filtered out before this method is called:

  ///   - non-array allocations never need a cookie

  ///   - calls to \::operator new(size_t, void*) never need a cookie

  ///

  /// \param expr - the new-expression being allocated.

  virtual CharUnits GetArrayCookieSize(const CXXNewExpr *expr);

  /// Initialize the array cookie for the given allocation.

  ///

  /// \param NewPtr - a char* which is the presumed-non-null

  ///   return value of the allocation function

  /// \param NumElements - the computed number of elements,

  ///   potentially collapsed from the multidimensional array case;

  ///   always a size_t

  /// \param ElementType - the base element allocated type,

  ///   i.e. the allocated type after stripping all array types

  virtual Address InitializeArrayCookie(CodeGenFunction &CGF,

                                        Address NewPtr,

                                        llvm::Value *NumElements,

                                        const CXXNewExpr *expr,

                                        QualType ElementType);

  /// Reads the array cookie associated with the given pointer,

  /// if it has one.

  ///

  /// \param Ptr - a pointer to the first element in the array

  /// \param ElementType - the base element type of elements of the array

  /// \param NumElements - an out parameter which will be initialized

  ///   with the number of elements allocated, or zero if there is no

  ///   cookie

  /// \param AllocPtr - an out parameter which will be initialized

  ///   with a char* pointing to the address returned by the allocation

  ///   function

  /// \param CookieSize - an out parameter which will be initialized

  ///   with the size of the cookie, or zero if there is no cookie

  virtual void ReadArrayCookie(CodeGenFunction &CGF, Address Ptr,

                               const CXXDeleteExpr *expr,

                               QualType ElementType, llvm::Value *&NumElements,

                               llvm::Value *&AllocPtr, CharUnits &CookieSize);

  /// Return whether the given global decl needs a VTT parameter.

  virtual bool NeedsVTTParameter(GlobalDecl GD);

protected:

  /// Returns the extra size required in order to store the array

  /// cookie for the given type.  Assumes that an array cookie is

  /// required.

  virtual CharUnits getArrayCookieSizeImpl(QualType elementType);

  /// Reads the array cookie for an allocation which is known to have one.

  /// This is called by the standard implementation of ReadArrayCookie.

  ///

  /// \param ptr - a pointer to the allocation made for an array, as a char*

  /// \param cookieSize - the computed cookie size of an array

  ///

  /// Other parameters are as above.

  ///

  /// \return a size_t

  virtual llvm::Value *readArrayCookieImpl(CodeGenFunction &IGF, Address ptr,

                                           CharUnits cookieSize);

public:

  /*************************** Static local guards ****************************/

  /// Emits the guarded initializer and destructor setup for the given

  /// variable, given that it couldn't be emitted as a constant.

  /// If \p PerformInit is false, the initialization has been folded to a

  /// constant and should not be performed.

  ///

  /// The variable may be:

  ///   - a static local variable

  ///   - a static data member of a class template instantiation

  virtual void EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D,

                               llvm::GlobalVariable *DeclPtr,

                               bool PerformInit) = 0;

  /// Emit code to force the execution of a destructor during global

  /// teardown.  The default implementation of this uses atexit.

  ///

  /// \param Dtor - a function taking a single pointer argument

  /// \param Addr - a pointer to pass to the destructor function.

  virtual void registerGlobalDtor(CodeGenFunction &CGF, const VarDecl &D,

                                  llvm::FunctionCallee Dtor,

                                  llvm::Constant *Addr) = 0;

  /*************************** thread_local initialization ********************/

  /// Emits ABI-required functions necessary to initialize thread_local

  /// variables in this translation unit.

  ///

  /// \param CXXThreadLocals - The thread_local declarations in this translation

  ///        unit.

  /// \param CXXThreadLocalInits - If this translation unit contains any

  ///        non-constant initialization or non-trivial destruction for

  ///        thread_local variables, a list of functions to perform the

  ///        initialization.

  virtual void EmitThreadLocalInitFuncs(

      CodeGenModule &CGM, ArrayRef<const VarDecl *> CXXThreadLocals,

      ArrayRef<llvm::Function *> CXXThreadLocalInits,

      ArrayRef<const VarDecl *> CXXThreadLocalInitVars) = 0;

  // Determine if references to thread_local global variables can be made

  // directly or require access through a thread wrapper function.

  virtual bool usesThreadWrapperFunction(const VarDecl *VD) const = 0;

  /// Emit a reference to a non-local thread_local variable (including

  /// triggering the initialization of all thread_local variables in its

  /// translation unit).

  virtual LValue EmitThreadLocalVarDeclLValue(CodeGenFunction &CGF,

                                              const VarDecl *VD,

                                              QualType LValType) = 0;

  /// Emit a single constructor/destructor with the given type from a C++

  /// constructor Decl.

  virtual void emitCXXStructor(GlobalDecl GD) = 0;

  /// Load a vtable from This, an object of polymorphic type RD, or from one of

  /// its virtual bases if it does not have its own vtable. Returns the vtable

  /// and the class from which the vtable was loaded.

  virtual std::pair<llvm::Value *, const CXXRecordDecl *>

  LoadVTablePtr(CodeGenFunction &CGF, Address This,

                const CXXRecordDecl *RD) = 0;

};

// Create an instance of a C++ ABI class:

/// Creates an Itanium-family ABI.

CGCXXABI *CreateItaniumCXXABI(CodeGenModule &CGM);

/// Creates a Microsoft-family ABI.

CGCXXABI *CreateMicrosoftCXXABI(CodeGenModule &CGM);

struct CatchRetScope final : EHScopeStack::Cleanup {

  llvm::CatchPadInst *CPI;

  CatchRetScope(llvm::CatchPadInst *CPI) : CPI(CPI) {}

  void Emit(CodeGenFunction &CGF, Flags flags) override {

    llvm::BasicBlock *BB = CGF.createBasicBlock("catchret.dest");

    CGF.Builder.CreateCatchRet(CPI, BB);

    CGF.EmitBlock(BB);

  }

};

}

}

#endif