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> SubVTTIndicesMapTy;
42
43 /// SubVTTIndices - Contains indices into the various sub-VTTs.
44 SubVTTIndicesMapTy SubVTTIndices;
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
78public:
79 /// Add vtable components for the given vtable layout to the given
80 /// global initializer.
81 void createVTableInitializer(ConstantStructBuilder &builder,
82 const VTableLayout &layout, llvm::Constant *rtti,
83 bool vtableHasLocalLinkage);
84
85 CodeGenVTables(CodeGenModule &CGM);
86
87 ItaniumVTableContext &getItaniumVTableContext() {
88 return *cast<ItaniumVTableContext>(Val: VTContext);
89 }
90
91 const ItaniumVTableContext &getItaniumVTableContext() const {
92 return *cast<ItaniumVTableContext>(Val: VTContext);
93 }
94
95 MicrosoftVTableContext &getMicrosoftVTableContext() {
96 return *cast<MicrosoftVTableContext>(Val: VTContext);
97 }
98
99 /// getSubVTTIndex - Return the index of the sub-VTT for the base class of the
100 /// given record decl.
101 uint64_t getSubVTTIndex(const CXXRecordDecl *RD, BaseSubobject Base);
102
103 /// getSecondaryVirtualPointerIndex - Return the index in the VTT where the
104 /// virtual pointer for the given subobject is located.
105 uint64_t getSecondaryVirtualPointerIndex(const CXXRecordDecl *RD,
106 BaseSubobject Base);
107
108 /// GenerateConstructionVTable - Generate a construction vtable for the given
109 /// base subobject.
110 llvm::GlobalVariable *
111 GenerateConstructionVTable(const CXXRecordDecl *RD, const BaseSubobject &Base,
112 bool BaseIsVirtual,
113 llvm::GlobalVariable::LinkageTypes Linkage,
114 VTableAddressPointsMapTy& AddressPoints);
115
116
117 /// GetAddrOfVTT - Get the address of the VTT for the given record decl.
118 llvm::GlobalVariable *GetAddrOfVTT(const CXXRecordDecl *RD);
119
120 /// EmitVTTDefinition - Emit the definition of the given vtable.
121 void EmitVTTDefinition(llvm::GlobalVariable *VTT,
122 llvm::GlobalVariable::LinkageTypes Linkage,
123 const CXXRecordDecl *RD);
124
125 /// EmitThunks - Emit the associated thunks for the given global decl.
126 void EmitThunks(GlobalDecl GD);
127
128 /// GenerateClassData - Generate all the class data required to be
129 /// generated upon definition of a KeyFunction. This includes the
130 /// vtable, the RTTI data structure (if RTTI is enabled) and the VTT
131 /// (if the class has virtual bases).
132 void GenerateClassData(const CXXRecordDecl *RD);
133
134 bool isVTableExternal(const CXXRecordDecl *RD);
135
136 /// Returns the type of a vtable with the given layout. Normally a struct of
137 /// arrays of pointers, with one struct element for each vtable in the vtable
138 /// group.
139 llvm::Type *getVTableType(const VTableLayout &layout);
140
141 /// Generate a public facing alias for the vtable and make the vtable either
142 /// hidden or private. The alias will have the original linkage and visibility
143 /// of the vtable. This is used for cases under the relative vtables ABI
144 /// when a vtable may not be dso_local.
145 void GenerateRelativeVTableAlias(llvm::GlobalVariable *VTable,
146 llvm::StringRef AliasNameRef);
147
148 /// Specify a global should not be instrumented with hwasan.
149 void RemoveHwasanMetadata(llvm::GlobalValue *GV) const;
150
151 /// Return the type used as components for a vtable.
152 llvm::Type *getVTableComponentType() const;
153
154 /// Return true if the relative vtable layout is used.
155 bool useRelativeLayout() const;
156};
157
158} // end namespace CodeGen
159} // end namespace clang
160#endif
161