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 bool useRelativeLayout() const; 79 80 llvm::Type *getVTableComponentType() const; 81 82 public: 83 /// Add vtable components for the given vtable layout to the given 84 /// global initializer. 85 void createVTableInitializer(ConstantStructBuilder &builder, 86 const VTableLayout &layout, llvm::Constant *rtti, 87 bool vtableHasLocalLinkage); 88 89 CodeGenVTables(CodeGenModule &CGM); 90 91 ItaniumVTableContext &getItaniumVTableContext() { 92 return *cast<ItaniumVTableContext>(VTContext); 93 } 94 95 const ItaniumVTableContext &getItaniumVTableContext() const { 96 return *cast<ItaniumVTableContext>(VTContext); 97 } 98 99 MicrosoftVTableContext &getMicrosoftVTableContext() { 100 return *cast<MicrosoftVTableContext>(VTContext); 101 } 102 103 /// getSubVTTIndex - Return the index of the sub-VTT for the base class of the 104 /// given record decl. 105 uint64_t getSubVTTIndex(const CXXRecordDecl *RD, BaseSubobject Base); 106 107 /// getSecondaryVirtualPointerIndex - Return the index in the VTT where the 108 /// virtual pointer for the given subobject is located. 109 uint64_t getSecondaryVirtualPointerIndex(const CXXRecordDecl *RD, 110 BaseSubobject Base); 111 112 /// GenerateConstructionVTable - Generate a construction vtable for the given 113 /// base subobject. 114 llvm::GlobalVariable * 115 GenerateConstructionVTable(const CXXRecordDecl *RD, const BaseSubobject &Base, 116 bool BaseIsVirtual, 117 llvm::GlobalVariable::LinkageTypes Linkage, 118 VTableAddressPointsMapTy& AddressPoints); 119 120 121 /// GetAddrOfVTT - Get the address of the VTT for the given record decl. 122 llvm::GlobalVariable *GetAddrOfVTT(const CXXRecordDecl *RD); 123 124 /// EmitVTTDefinition - Emit the definition of the given vtable. 125 void EmitVTTDefinition(llvm::GlobalVariable *VTT, 126 llvm::GlobalVariable::LinkageTypes Linkage, 127 const CXXRecordDecl *RD); 128 129 /// EmitThunks - Emit the associated thunks for the given global decl. 130 void EmitThunks(GlobalDecl GD); 131 132 /// GenerateClassData - Generate all the class data required to be 133 /// generated upon definition of a KeyFunction. This includes the 134 /// vtable, the RTTI data structure (if RTTI is enabled) and the VTT 135 /// (if the class has virtual bases). 136 void GenerateClassData(const CXXRecordDecl *RD); 137 138 bool isVTableExternal(const CXXRecordDecl *RD); 139 140 /// Returns the type of a vtable with the given layout. Normally a struct of 141 /// arrays of pointers, with one struct element for each vtable in the vtable 142 /// group. 143 llvm::Type *getVTableType(const VTableLayout &layout); 144 145 /// Generate a public facing alias for the vtable and make the vtable either 146 /// hidden or private. The alias will have the original linkage and visibility 147 /// of the vtable. This is used for cases under the relative vtables ABI 148 /// when a vtable may not be dso_local. 149 void GenerateRelativeVTableAlias(llvm::GlobalVariable *VTable, 150 llvm::StringRef AliasNameRef); 151 152 /// Specify a global should not be instrumented with hwasan. 153 void RemoveHwasanMetadata(llvm::GlobalValue *GV) const; 154 }; 155 156 } // end namespace CodeGen 157 } // end namespace clang 158 #endif 159