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
24namespace clang {
25 class CXXRecordDecl;
26
27namespace CodeGen {
28 class CodeGenModule;
29 class ConstantArrayBuilder;
30 class ConstantStructBuilder;
31
32class 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
92public:
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

source code of clang/lib/CodeGen/CGVTables.h