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//===--- CGVTables.h - Emit LLVM Code for C++ vtables -----------*- C++ -*-===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
// This contains code dealing with C++ code generation of virtual tables.
#include "clang/AST/BaseSubobject.h"
#include "clang/AST/CharUnits.h"
#include "clang/AST/GlobalDecl.h"
#include "clang/AST/VTableBuilder.h"
#include "clang/Basic/ABI.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/IR/GlobalVariable.h"
namespace clang {
class CXXRecordDecl;
namespace CodeGen {
class CodeGenModule;
class ConstantArrayBuilder;
class ConstantStructBuilder;
class CodeGenVTables {
CodeGenModule &CGM;
VTableContextBase *VTContext;
/// VTableAddressPointsMapTy - Address points for a single vtable.
typedef VTableLayout::AddressPointsMapTy VTableAddressPointsMapTy;
typedef std::pair<const CXXRecordDecl *, BaseSubobject> BaseSubobjectPairTy;
typedef llvm::DenseMap<BaseSubobjectPairTy, uint64_t> SubVTTIndiciesMapTy;
/// SubVTTIndicies - Contains indices into the various sub-VTTs.
SubVTTIndiciesMapTy SubVTTIndicies;
typedef llvm::DenseMap<BaseSubobjectPairTy, uint64_t>
/// SecondaryVirtualPointerIndices - Contains the secondary virtual pointer
/// indices.
SecondaryVirtualPointerIndicesMapTy SecondaryVirtualPointerIndices;
/// Cache for the pure virtual member call function.
llvm::Constant *PureVirtualFn = nullptr;
/// Cache for the deleted virtual member call function.
llvm::Constant *DeletedVirtualFn = nullptr;
/// Get the address of a thunk and emit it if necessary.
llvm::Constant *maybeEmitThunk(GlobalDecl GD,
const ThunkInfo &ThunkAdjustments,
bool ForVTable);
void addVTableComponent(ConstantArrayBuilder &builder,
const VTableLayout &layout, unsigned componentIndex,
llvm::Constant *rtti, unsigned &nextVTableThunkIndex,
unsigned vtableAddressPoint,
bool vtableHasLocalLinkage);
/// Add a 32-bit offset to a component relative to the vtable when using the
/// relative vtables ABI. The array builder points to the start of the vtable.
void addRelativeComponent(ConstantArrayBuilder &builder,
llvm::Constant *component,
unsigned vtableAddressPoint,
bool vtableHasLocalLinkage,
bool isCompleteDtor) const;
/// Create a dso_local stub that will be used for a relative reference in the
/// relative vtable layout. This stub will just be a tail call to the original
/// function and propagate any function attributes from the original. If the
/// original function is already dso_local, the original is returned instead
/// and a stub is not created.
llvm::Function *
getOrCreateRelativeStub(llvm::Function *func,
llvm::GlobalValue::LinkageTypes stubLinkage,
bool isCompleteDtor) const;
bool useRelativeLayout() const;
llvm::Type *getVTableComponentType() const;
/// Add vtable components for the given vtable layout to the given
/// global initializer.
void createVTableInitializer(ConstantStructBuilder &builder,
const VTableLayout &layout, llvm::Constant *rtti,
bool vtableHasLocalLinkage);
CodeGenVTables(CodeGenModule &CGM);
ItaniumVTableContext &getItaniumVTableContext() {
return *cast<ItaniumVTableContext>(VTContext);
MicrosoftVTableContext &getMicrosoftVTableContext() {
return *cast<MicrosoftVTableContext>(VTContext);
/// getSubVTTIndex - Return the index of the sub-VTT for the base class of the
/// given record decl.
uint64_t getSubVTTIndex(const CXXRecordDecl *RD, BaseSubobject Base);
/// getSecondaryVirtualPointerIndex - Return the index in the VTT where the
/// virtual pointer for the given subobject is located.
uint64_t getSecondaryVirtualPointerIndex(const CXXRecordDecl *RD,
BaseSubobject Base);
/// GenerateConstructionVTable - Generate a construction vtable for the given
/// base subobject.
llvm::GlobalVariable *
GenerateConstructionVTable(const CXXRecordDecl *RD, const BaseSubobject &Base,
bool BaseIsVirtual,
llvm::GlobalVariable::LinkageTypes Linkage,
VTableAddressPointsMapTy& AddressPoints);
/// GetAddrOfVTT - Get the address of the VTT for the given record decl.
llvm::GlobalVariable *GetAddrOfVTT(const CXXRecordDecl *RD);
/// EmitVTTDefinition - Emit the definition of the given vtable.
void EmitVTTDefinition(llvm::GlobalVariable *VTT,
llvm::GlobalVariable::LinkageTypes Linkage,
const CXXRecordDecl *RD);
/// EmitThunks - Emit the associated thunks for the given global decl.
void EmitThunks(GlobalDecl GD);
/// GenerateClassData - Generate all the class data required to be
/// generated upon definition of a KeyFunction. This includes the
/// vtable, the RTTI data structure (if RTTI is enabled) and the VTT
/// (if the class has virtual bases).
void GenerateClassData(const CXXRecordDecl *RD);
bool isVTableExternal(const CXXRecordDecl *RD);
/// Returns the type of a vtable with the given layout. Normally a struct of
/// arrays of pointers, with one struct element for each vtable in the vtable
/// group.
llvm::Type *getVTableType(const VTableLayout &layout);
/// Generate a public facing alias for the vtable and make the vtable either
/// hidden or private. The alias will have the original linkage and visibility
/// of the vtable. This is used for cases under the relative vtables ABI
/// when a vtable may not be dso_local.
void GenerateRelativeVTableAlias(llvm::GlobalVariable *VTable,
llvm::StringRef AliasNameRef);
} // end namespace CodeGen
} // end namespace clang