d905da4a5f
The pointer for a class's RTTI data comes right before the VFTable but has no name. To be properly compatible with this, we do the following: * Create a single GlobalVariable which holds the contents of the VFTable _and_ the pointer to the RTTI data. * Create a GlobalAlias, with appropriate linkage/visibility, that points just after the RTTI data pointer. This ensures that the VFTable symbol will always refer to VFTable data. * Create a Comdat with a "Largest" SelectionKind and stick the private GlobalVariable in it. By transitivity, the GlobalAlias will be a member of the Comdat group. Using "Largest" ensures that foreign definitions without an RTTI data pointer will _not_ be chosen in the final linked image. Whether or not we emit RTTI data depends on several things: * The -fno-rtti flag implies that we should never not emit a pointer to RTTI data before the VFTable. * __declspec(dllimport) brings in the VFTable from a remote DLL. Use an available_externally GlobalVariable to provide a local definition of the VFTable. This means that we won't have any available_externally definitions of things like complete object locators. This is acceptable because they are never directly referenced. To my knowledge, this completes the implementation of MSVC RTTI code generation. Further semantic work should be done to properly support /GR-. llvm-svn: 212125
124 lines
4.5 KiB
C++
124 lines
4.5 KiB
C++
//===--- CGVTables.h - Emit LLVM Code for C++ vtables -----------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This contains code dealing with C++ code generation of virtual tables.
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//
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//===----------------------------------------------------------------------===//
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#ifndef CLANG_CODEGEN_CGVTABLE_H
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#define CLANG_CODEGEN_CGVTABLE_H
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#include "clang/AST/BaseSubobject.h"
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#include "clang/AST/CharUnits.h"
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#include "clang/AST/GlobalDecl.h"
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#include "clang/AST/VTableBuilder.h"
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#include "clang/Basic/ABI.h"
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#include "llvm/ADT/DenseMap.h"
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#include "llvm/IR/GlobalVariable.h"
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namespace clang {
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class CXXRecordDecl;
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namespace CodeGen {
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class CodeGenModule;
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class CodeGenVTables {
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CodeGenModule &CGM;
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VTableContextBase *VTContext;
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/// VTableAddressPointsMapTy - Address points for a single vtable.
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typedef llvm::DenseMap<BaseSubobject, uint64_t> VTableAddressPointsMapTy;
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typedef std::pair<const CXXRecordDecl *, BaseSubobject> BaseSubobjectPairTy;
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typedef llvm::DenseMap<BaseSubobjectPairTy, uint64_t> SubVTTIndiciesMapTy;
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/// SubVTTIndicies - Contains indices into the various sub-VTTs.
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SubVTTIndiciesMapTy SubVTTIndicies;
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typedef llvm::DenseMap<BaseSubobjectPairTy, uint64_t>
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SecondaryVirtualPointerIndicesMapTy;
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/// SecondaryVirtualPointerIndices - Contains the secondary virtual pointer
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/// indices.
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SecondaryVirtualPointerIndicesMapTy SecondaryVirtualPointerIndices;
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/// emitThunk - Emit a single thunk.
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void emitThunk(GlobalDecl GD, const ThunkInfo &Thunk, bool ForVTable);
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/// maybeEmitThunkForVTable - Emit the given thunk for the vtable if needed by
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/// the ABI.
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void maybeEmitThunkForVTable(GlobalDecl GD, const ThunkInfo &Thunk);
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public:
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/// CreateVTableInitializer - Create a vtable initializer for the given record
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/// decl.
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/// \param Components - The vtable components; this is really an array of
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/// VTableComponents.
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llvm::Constant *CreateVTableInitializer(
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const CXXRecordDecl *RD, const VTableComponent *Components,
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unsigned NumComponents, const VTableLayout::VTableThunkTy *VTableThunks,
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unsigned NumVTableThunks, llvm::Constant *RTTI);
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CodeGenVTables(CodeGenModule &CGM);
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ItaniumVTableContext &getItaniumVTableContext() {
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return *cast<ItaniumVTableContext>(VTContext);
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}
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MicrosoftVTableContext &getMicrosoftVTableContext() {
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return *cast<MicrosoftVTableContext>(VTContext);
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}
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/// getSubVTTIndex - Return the index of the sub-VTT for the base class of the
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/// given record decl.
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uint64_t getSubVTTIndex(const CXXRecordDecl *RD, BaseSubobject Base);
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/// getSecondaryVirtualPointerIndex - Return the index in the VTT where the
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/// virtual pointer for the given subobject is located.
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uint64_t getSecondaryVirtualPointerIndex(const CXXRecordDecl *RD,
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BaseSubobject Base);
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/// getAddressPoint - Get the address point of the given subobject in the
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/// class decl.
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uint64_t getAddressPoint(BaseSubobject Base, const CXXRecordDecl *RD);
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/// GenerateConstructionVTable - Generate a construction vtable for the given
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/// base subobject.
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llvm::GlobalVariable *
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GenerateConstructionVTable(const CXXRecordDecl *RD, const BaseSubobject &Base,
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bool BaseIsVirtual,
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llvm::GlobalVariable::LinkageTypes Linkage,
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VTableAddressPointsMapTy& AddressPoints);
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/// GetAddrOfVTT - Get the address of the VTT for the given record decl.
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llvm::GlobalVariable *GetAddrOfVTT(const CXXRecordDecl *RD);
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/// EmitVTTDefinition - Emit the definition of the given vtable.
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void EmitVTTDefinition(llvm::GlobalVariable *VTT,
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llvm::GlobalVariable::LinkageTypes Linkage,
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const CXXRecordDecl *RD);
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/// EmitThunks - Emit the associated thunks for the given global decl.
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void EmitThunks(GlobalDecl GD);
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/// GenerateClassData - Generate all the class data required to be
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/// generated upon definition of a KeyFunction. This includes the
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/// vtable, the RTTI data structure (if RTTI is enabled) and the VTT
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/// (if the class has virtual bases).
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void GenerateClassData(const CXXRecordDecl *RD);
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bool isVTableExternal(const CXXRecordDecl *RD);
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};
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} // end namespace CodeGen
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} // end namespace clang
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#endif
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