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1 //===--- CGVTables.h - Emit LLVM Code for C++ vtables -----------*- C++ -*-===//
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2 //
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3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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4 // See https://llvm.org/LICENSE.txt for license information.
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5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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6 //
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7 //===----------------------------------------------------------------------===//
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8 //
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9 // This contains code dealing with C++ code generation of virtual tables.
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10 //
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11 //===----------------------------------------------------------------------===//
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12
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13 #ifndef LLVM_CLANG_LIB_CODEGEN_CGVTABLES_H
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14 #define LLVM_CLANG_LIB_CODEGEN_CGVTABLES_H
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15
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16 #include "clang/AST/BaseSubobject.h"
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17 #include "clang/AST/CharUnits.h"
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18 #include "clang/AST/GlobalDecl.h"
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19 #include "clang/AST/VTableBuilder.h"
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20 #include "clang/Basic/ABI.h"
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21 #include "llvm/ADT/DenseMap.h"
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22 #include "llvm/IR/GlobalVariable.h"
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23
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24 namespace clang {
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25 class CXXRecordDecl;
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26
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27 namespace CodeGen {
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28 class CodeGenModule;
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29 class ConstantArrayBuilder;
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30 class ConstantStructBuilder;
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31
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32 class CodeGenVTables {
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33 CodeGenModule &CGM;
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34
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35 VTableContextBase *VTContext;
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36
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37 /// VTableAddressPointsMapTy - Address points for a single vtable.
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38 typedef VTableLayout::AddressPointsMapTy VTableAddressPointsMapTy;
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39
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40 typedef std::pair<const CXXRecordDecl *, BaseSubobject> BaseSubobjectPairTy;
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41 typedef llvm::DenseMap<BaseSubobjectPairTy, uint64_t> SubVTTIndiciesMapTy;
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42
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43 /// SubVTTIndicies - Contains indices into the various sub-VTTs.
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44 SubVTTIndiciesMapTy SubVTTIndicies;
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45
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46 typedef llvm::DenseMap<BaseSubobjectPairTy, uint64_t>
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47 SecondaryVirtualPointerIndicesMapTy;
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48
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49 /// SecondaryVirtualPointerIndices - Contains the secondary virtual pointer
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50 /// indices.
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51 SecondaryVirtualPointerIndicesMapTy SecondaryVirtualPointerIndices;
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52
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53 /// Cache for the pure virtual member call function.
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54 llvm::Constant *PureVirtualFn = nullptr;
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55
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56 /// Cache for the deleted virtual member call function.
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57 llvm::Constant *DeletedVirtualFn = nullptr;
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58
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59 /// Get the address of a thunk and emit it if necessary.
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60 llvm::Constant *maybeEmitThunk(GlobalDecl GD,
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61 const ThunkInfo &ThunkAdjustments,
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62 bool ForVTable);
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63
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64 void addVTableComponent(ConstantArrayBuilder &builder,
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65 const VTableLayout &layout, unsigned componentIndex,
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66 llvm::Constant *rtti, unsigned &nextVTableThunkIndex,
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67 unsigned vtableAddressPoint,
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68 bool vtableHasLocalLinkage);
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69
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70 /// Add a 32-bit offset to a component relative to the vtable when using the
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71 /// relative vtables ABI. The array builder points to the start of the vtable.
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72 void addRelativeComponent(ConstantArrayBuilder &builder,
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73 llvm::Constant *component,
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74 unsigned vtableAddressPoint,
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75 bool vtableHasLocalLinkage,
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76 bool isCompleteDtor) const;
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77
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78 /// Create a dso_local stub that will be used for a relative reference in the
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79 /// relative vtable layout. This stub will just be a tail call to the original
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80 /// function and propagate any function attributes from the original. If the
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81 /// original function is already dso_local, the original is returned instead
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82 /// and a stub is not created.
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83 llvm::Function *
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84 getOrCreateRelativeStub(llvm::Function *func,
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85 llvm::GlobalValue::LinkageTypes stubLinkage,
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86 bool isCompleteDtor) const;
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87
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88 bool useRelativeLayout() const;
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89
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90 llvm::Type *getVTableComponentType() const;
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150
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91
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92 public:
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93 /// Add vtable components for the given vtable layout to the given
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94 /// global initializer.
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95 void createVTableInitializer(ConstantStructBuilder &builder,
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221
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96 const VTableLayout &layout, llvm::Constant *rtti,
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97 bool vtableHasLocalLinkage);
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98
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99 CodeGenVTables(CodeGenModule &CGM);
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100
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101 ItaniumVTableContext &getItaniumVTableContext() {
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102 return *cast<ItaniumVTableContext>(VTContext);
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103 }
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104
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105 MicrosoftVTableContext &getMicrosoftVTableContext() {
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106 return *cast<MicrosoftVTableContext>(VTContext);
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107 }
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108
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109 /// getSubVTTIndex - Return the index of the sub-VTT for the base class of the
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110 /// given record decl.
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111 uint64_t getSubVTTIndex(const CXXRecordDecl *RD, BaseSubobject Base);
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112
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113 /// getSecondaryVirtualPointerIndex - Return the index in the VTT where the
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114 /// virtual pointer for the given subobject is located.
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115 uint64_t getSecondaryVirtualPointerIndex(const CXXRecordDecl *RD,
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116 BaseSubobject Base);
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117
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118 /// GenerateConstructionVTable - Generate a construction vtable for the given
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119 /// base subobject.
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120 llvm::GlobalVariable *
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121 GenerateConstructionVTable(const CXXRecordDecl *RD, const BaseSubobject &Base,
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122 bool BaseIsVirtual,
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123 llvm::GlobalVariable::LinkageTypes Linkage,
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124 VTableAddressPointsMapTy& AddressPoints);
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125
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126
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127 /// GetAddrOfVTT - Get the address of the VTT for the given record decl.
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128 llvm::GlobalVariable *GetAddrOfVTT(const CXXRecordDecl *RD);
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129
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130 /// EmitVTTDefinition - Emit the definition of the given vtable.
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131 void EmitVTTDefinition(llvm::GlobalVariable *VTT,
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132 llvm::GlobalVariable::LinkageTypes Linkage,
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133 const CXXRecordDecl *RD);
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134
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135 /// EmitThunks - Emit the associated thunks for the given global decl.
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136 void EmitThunks(GlobalDecl GD);
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137
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138 /// GenerateClassData - Generate all the class data required to be
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139 /// generated upon definition of a KeyFunction. This includes the
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140 /// vtable, the RTTI data structure (if RTTI is enabled) and the VTT
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141 /// (if the class has virtual bases).
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142 void GenerateClassData(const CXXRecordDecl *RD);
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143
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144 bool isVTableExternal(const CXXRecordDecl *RD);
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145
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146 /// Returns the type of a vtable with the given layout. Normally a struct of
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147 /// arrays of pointers, with one struct element for each vtable in the vtable
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148 /// group.
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149 llvm::Type *getVTableType(const VTableLayout &layout);
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221
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150
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151 /// Generate a public facing alias for the vtable and make the vtable either
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152 /// hidden or private. The alias will have the original linkage and visibility
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153 /// of the vtable. This is used for cases under the relative vtables ABI
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154 /// when a vtable may not be dso_local.
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155 void GenerateRelativeVTableAlias(llvm::GlobalVariable *VTable,
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156 llvm::StringRef AliasNameRef);
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150
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157 };
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158
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159 } // end namespace CodeGen
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160 } // end namespace clang
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161 #endif
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