1 //===--- CGVTables.h - Emit LLVM Code for C++ vtables -----------*- C++ -*-===// 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-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // This contains code dealing with C++ code generation of virtual tables. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #ifndef LLVM_CLANG_LIB_CODEGEN_CGVTABLES_H 14 #define LLVM_CLANG_LIB_CODEGEN_CGVTABLES_H 15 16 #include "clang/AST/BaseSubobject.h" 17 #include "clang/AST/CharUnits.h" 18 #include "clang/AST/GlobalDecl.h" 19 #include "clang/AST/VTableBuilder.h" 20 #include "clang/Basic/ABI.h" 21 #include "llvm/ADT/DenseMap.h" 22 #include "llvm/IR/GlobalVariable.h" 23 24 namespace clang { 25 class CXXRecordDecl; 26 27 namespace CodeGen { 28 class CodeGenModule; 29 class ConstantArrayBuilder; 30 class ConstantStructBuilder; 31 32 class CodeGenVTables { 33 CodeGenModule &CGM; 34 35 VTableContextBase *VTContext; 36 37 /// VTableAddressPointsMapTy - Address points for a single vtable. 38 typedef VTableLayout::AddressPointsMapTy VTableAddressPointsMapTy; 39 40 typedef std::pair<const CXXRecordDecl *, BaseSubobject> BaseSubobjectPairTy; 41 typedef llvm::DenseMap<BaseSubobjectPairTy, uint64_t> SubVTTIndiciesMapTy; 42 43 /// SubVTTIndicies - Contains indices into the various sub-VTTs. 44 SubVTTIndiciesMapTy SubVTTIndicies; 45 46 typedef llvm::DenseMap<BaseSubobjectPairTy, uint64_t> 47 SecondaryVirtualPointerIndicesMapTy; 48 49 /// SecondaryVirtualPointerIndices - Contains the secondary virtual pointer 50 /// indices. 51 SecondaryVirtualPointerIndicesMapTy SecondaryVirtualPointerIndices; 52 53 /// Cache for the pure virtual member call function. 54 llvm::Constant *PureVirtualFn = nullptr; 55 56 /// Cache for the deleted virtual member call function. 57 llvm::Constant *DeletedVirtualFn = nullptr; 58 59 /// Get the address of a thunk and emit it if necessary. 60 llvm::Constant *maybeEmitThunk(GlobalDecl GD, 61 const ThunkInfo &ThunkAdjustments, 62 bool ForVTable); 63 64 void addVTableComponent(ConstantArrayBuilder &builder, 65 const VTableLayout &layout, unsigned componentIndex, 66 llvm::Constant *rtti, unsigned &nextVTableThunkIndex, 67 unsigned vtableAddressPoint, 68 bool vtableHasLocalLinkage); 69 70 /// Add a 32-bit offset to a component relative to the vtable when using the 71 /// relative vtables ABI. The array builder points to the start of the vtable. 72 void addRelativeComponent(ConstantArrayBuilder &builder, 73 llvm::Constant *component, 74 unsigned vtableAddressPoint, 75 bool vtableHasLocalLinkage, 76 bool isCompleteDtor) const; 77 78 /// Create a dso_local stub that will be used for a relative reference in the 79 /// relative vtable layout. This stub will just be a tail call to the original 80 /// function and propagate any function attributes from the original. If the 81 /// original function is already dso_local, the original is returned instead 82 /// and a stub is not created. 83 llvm::Function * 84 getOrCreateRelativeStub(llvm::Function *func, 85 llvm::GlobalValue::LinkageTypes stubLinkage, 86 bool isCompleteDtor) const; 87 88 bool useRelativeLayout() const; 89 90 llvm::Type *getVTableComponentType() const; 91 92 public: 93 /// Add vtable components for the given vtable layout to the given 94 /// global initializer. 95 void createVTableInitializer(ConstantStructBuilder &builder, 96 const VTableLayout &layout, llvm::Constant *rtti, 97 bool vtableHasLocalLinkage); 98 99 CodeGenVTables(CodeGenModule &CGM); 100 101 ItaniumVTableContext &getItaniumVTableContext() { 102 return *cast<ItaniumVTableContext>(VTContext); 103 } 104 105 MicrosoftVTableContext &getMicrosoftVTableContext() { 106 return *cast<MicrosoftVTableContext>(VTContext); 107 } 108 109 /// getSubVTTIndex - Return the index of the sub-VTT for the base class of the 110 /// given record decl. 111 uint64_t getSubVTTIndex(const CXXRecordDecl *RD, BaseSubobject Base); 112 113 /// getSecondaryVirtualPointerIndex - Return the index in the VTT where the 114 /// virtual pointer for the given subobject is located. 115 uint64_t getSecondaryVirtualPointerIndex(const CXXRecordDecl *RD, 116 BaseSubobject Base); 117 118 /// GenerateConstructionVTable - Generate a construction vtable for the given 119 /// base subobject. 120 llvm::GlobalVariable * 121 GenerateConstructionVTable(const CXXRecordDecl *RD, const BaseSubobject &Base, 122 bool BaseIsVirtual, 123 llvm::GlobalVariable::LinkageTypes Linkage, 124 VTableAddressPointsMapTy& AddressPoints); 125 126 127 /// GetAddrOfVTT - Get the address of the VTT for the given record decl. 128 llvm::GlobalVariable *GetAddrOfVTT(const CXXRecordDecl *RD); 129 130 /// EmitVTTDefinition - Emit the definition of the given vtable. 131 void EmitVTTDefinition(llvm::GlobalVariable *VTT, 132 llvm::GlobalVariable::LinkageTypes Linkage, 133 const CXXRecordDecl *RD); 134 135 /// EmitThunks - Emit the associated thunks for the given global decl. 136 void EmitThunks(GlobalDecl GD); 137 138 /// GenerateClassData - Generate all the class data required to be 139 /// generated upon definition of a KeyFunction. This includes the 140 /// vtable, the RTTI data structure (if RTTI is enabled) and the VTT 141 /// (if the class has virtual bases). 142 void GenerateClassData(const CXXRecordDecl *RD); 143 144 bool isVTableExternal(const CXXRecordDecl *RD); 145 146 /// Returns the type of a vtable with the given layout. Normally a struct of 147 /// arrays of pointers, with one struct element for each vtable in the vtable 148 /// group. 149 llvm::Type *getVTableType(const VTableLayout &layout); 150 151 /// Generate a public facing alias for the vtable and make the vtable either 152 /// hidden or private. The alias will have the original linkage and visibility 153 /// of the vtable. This is used for cases under the relative vtables ABI 154 /// when a vtable may not be dso_local. 155 void GenerateRelativeVTableAlias(llvm::GlobalVariable *VTable, 156 llvm::StringRef AliasNameRef); 157 }; 158 159 } // end namespace CodeGen 160 } // end namespace clang 161 #endif 162
Indexes created Tue Jun 09 00:24:00 UTC 2026