1//===- VTTBuilder.h - C++ VTT layout builder --------------------*- 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 generation of the layout of virtual table
10// tables (VTT).
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_CLANG_AST_VTTBUILDER_H
15#define LLVM_CLANG_AST_VTTBUILDER_H
16
17#include "clang/AST/BaseSubobject.h"
18#include "clang/AST/CharUnits.h"
19#include "clang/Basic/LLVM.h"
20#include "llvm/ADT/DenseMap.h"
21#include "llvm/ADT/PointerIntPair.h"
22#include "llvm/ADT/SmallPtrSet.h"
23#include "llvm/ADT/SmallVector.h"
24#include <cstdint>
25
26namespace clang {
27
28class ASTContext;
29class ASTRecordLayout;
30class CXXRecordDecl;
31
32class VTTVTable {
33 llvm::PointerIntPair<const CXXRecordDecl *, 1, bool> BaseAndIsVirtual;
34 CharUnits BaseOffset;
35
36public:
37 VTTVTable() = default;
38 VTTVTable(const CXXRecordDecl *Base, CharUnits BaseOffset, bool BaseIsVirtual)
39 : BaseAndIsVirtual(Base, BaseIsVirtual), BaseOffset(BaseOffset) {}
40 VTTVTable(BaseSubobject Base, bool BaseIsVirtual)
41 : BaseAndIsVirtual(Base.getBase(), BaseIsVirtual),
42 BaseOffset(Base.getBaseOffset()) {}
43
44 const CXXRecordDecl *getBase() const {
45 return BaseAndIsVirtual.getPointer();
46 }
47
48 CharUnits getBaseOffset() const {
49 return BaseOffset;
50 }
51
52 bool isVirtual() const {
53 return BaseAndIsVirtual.getInt();
54 }
55
56 BaseSubobject getBaseSubobject() const {
57 return BaseSubobject(getBase(), getBaseOffset());
58 }
59};
60
61struct VTTComponent {
62 uint64_t VTableIndex;
63 BaseSubobject VTableBase;
64
65 VTTComponent() = default;
66 VTTComponent(uint64_t VTableIndex, BaseSubobject VTableBase)
67 : VTableIndex(VTableIndex), VTableBase(VTableBase) {}
68};
69
70/// Class for building VTT layout information.
71class VTTBuilder {
72 ASTContext &Ctx;
73
74 /// The most derived class for which we're building this vtable.
75 const CXXRecordDecl *MostDerivedClass;
76
77 using VTTVTablesVectorTy = SmallVector<VTTVTable, 64>;
78
79 /// The VTT vtables.
80 VTTVTablesVectorTy VTTVTables;
81
82 using VTTComponentsVectorTy = SmallVector<VTTComponent, 64>;
83
84 /// The VTT components.
85 VTTComponentsVectorTy VTTComponents;
86
87 /// The AST record layout of the most derived class.
88 const ASTRecordLayout &MostDerivedClassLayout;
89
90 using VisitedVirtualBasesSetTy = llvm::SmallPtrSet<const CXXRecordDecl *, 4>;
91
92 using AddressPointsMapTy = llvm::DenseMap<BaseSubobject, uint64_t>;
93
94 /// The sub-VTT indices for the bases of the most derived class.
95 llvm::DenseMap<BaseSubobject, uint64_t> SubVTTIndices;
96
97 /// The secondary virtual pointer indices of all subobjects of
98 /// the most derived class.
99 llvm::DenseMap<BaseSubobject, uint64_t> SecondaryVirtualPointerIndices;
100
101 /// Whether the VTT builder should generate LLVM IR for the VTT.
102 bool GenerateDefinition;
103
104 /// Add a vtable pointer to the VTT currently being built.
105 void AddVTablePointer(BaseSubobject Base, uint64_t VTableIndex,
106 const CXXRecordDecl *VTableClass);
107
108 /// Lay out the secondary VTTs of the given base subobject.
109 void LayoutSecondaryVTTs(BaseSubobject Base);
110
111 /// Lay out the secondary virtual pointers for the given base
112 /// subobject.
113 ///
114 /// \param BaseIsMorallyVirtual whether the base subobject is a virtual base
115 /// or a direct or indirect base of a virtual base.
116 void LayoutSecondaryVirtualPointers(BaseSubobject Base,
117 bool BaseIsMorallyVirtual,
118 uint64_t VTableIndex,
119 const CXXRecordDecl *VTableClass,
120 VisitedVirtualBasesSetTy &VBases);
121
122 /// Lay out the secondary virtual pointers for the given base
123 /// subobject.
124 void LayoutSecondaryVirtualPointers(BaseSubobject Base,
125 uint64_t VTableIndex);
126
127 /// Lay out the VTTs for the virtual base classes of the given
128 /// record declaration.
129 void LayoutVirtualVTTs(const CXXRecordDecl *RD,
130 VisitedVirtualBasesSetTy &VBases);
131
132 /// Lay out the VTT for the given subobject, including any
133 /// secondary VTTs, secondary virtual pointers and virtual VTTs.
134 void LayoutVTT(BaseSubobject Base, bool BaseIsVirtual);
135
136public:
137 VTTBuilder(ASTContext &Ctx, const CXXRecordDecl *MostDerivedClass,
138 bool GenerateDefinition);
139
140 // Returns a reference to the VTT components.
141 const VTTComponentsVectorTy &getVTTComponents() const {
142 return VTTComponents;
143 }
144
145 // Returns a reference to the VTT vtables.
146 const VTTVTablesVectorTy &getVTTVTables() const {
147 return VTTVTables;
148 }
149
150 /// Returns a reference to the sub-VTT indices.
151 const llvm::DenseMap<BaseSubobject, uint64_t> &getSubVTTIndices() const {
152 return SubVTTIndices;
153 }
154
155 /// Returns a reference to the secondary virtual pointer indices.
156 const llvm::DenseMap<BaseSubobject, uint64_t> &
157 getSecondaryVirtualPointerIndices() const {
158 return SecondaryVirtualPointerIndices;
159 }
160};
161
162} // namespace clang
163
164#endif // LLVM_CLANG_AST_VTTBUILDER_H
165