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 | |
26 | namespace clang { |
27 | |
28 | class ASTContext; |
29 | class ASTRecordLayout; |
30 | class CXXRecordDecl; |
31 | |
32 | class VTTVTable { |
33 | llvm::PointerIntPair<const CXXRecordDecl *, 1, bool> BaseAndIsVirtual; |
34 | CharUnits BaseOffset; |
35 | |
36 | public: |
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 | |
61 | struct 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. |
71 | class 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> SubVTTIndicies; |
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 | |
136 | public: |
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> &getSubVTTIndicies() const { |
152 | return SubVTTIndicies; |
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 | |