CGVTables.h revision 226890 
1//===--- CGVTables.h - Emit LLVM Code for C++ vtables -----------*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This contains code dealing with C++ code generation of virtual tables.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef CLANG_CODEGEN_CGVTABLE_H
15#define CLANG_CODEGEN_CGVTABLE_H
16
17#include "llvm/ADT/DenseMap.h"
18#include "llvm/GlobalVariable.h"
19#include "clang/Basic/ABI.h"
20#include "clang/AST/BaseSubobject.h"
21#include "clang/AST/CharUnits.h"
22#include "clang/AST/GlobalDecl.h"
23#include "clang/AST/VTableBuilder.h"
24
25namespace clang {
26  class CXXRecordDecl;
27
28namespace CodeGen {
29  class CodeGenModule;
30
31class CodeGenVTables {
32  CodeGenModule &CGM;
33
34  VTableContext VTContext;
35
36  /// VTables - All the vtables which have been defined.
37  llvm::DenseMap<const CXXRecordDecl *, llvm::GlobalVariable *> VTables;
38
39  /// VTableAddressPointsMapTy - Address points for a single vtable.
40  typedef llvm::DenseMap<BaseSubobject, uint64_t> VTableAddressPointsMapTy;
41
42  typedef std::pair<const CXXRecordDecl *, BaseSubobject> BaseSubobjectPairTy;
43  typedef llvm::DenseMap<BaseSubobjectPairTy, uint64_t> SubVTTIndiciesMapTy;
44
45  /// SubVTTIndicies - Contains indices into the various sub-VTTs.
46  SubVTTIndiciesMapTy SubVTTIndicies;
47
48  typedef llvm::DenseMap<BaseSubobjectPairTy, uint64_t>
49    SecondaryVirtualPointerIndicesMapTy;
50
51  /// SecondaryVirtualPointerIndices - Contains the secondary virtual pointer
52  /// indices.
53  SecondaryVirtualPointerIndicesMapTy SecondaryVirtualPointerIndices;
54
55  /// EmitThunk - Emit a single thunk.
56  void EmitThunk(GlobalDecl GD, const ThunkInfo &Thunk,
57                 bool UseAvailableExternallyLinkage);
58
59  /// MaybeEmitThunkAvailableExternally - Try to emit the given thunk with
60  /// available_externally linkage to allow for inlining of thunks.
61  /// This will be done iff optimizations are enabled and the member function
62  /// doesn't contain any incomplete types.
63  void MaybeEmitThunkAvailableExternally(GlobalDecl GD, const ThunkInfo &Thunk);
64
65  /// CreateVTableInitializer - Create a vtable initializer for the given record
66  /// decl.
67  /// \param Components - The vtable components; this is really an array of
68  /// VTableComponents.
69  llvm::Constant *CreateVTableInitializer(const CXXRecordDecl *RD,
70                                          const VTableComponent *Components,
71                                          unsigned NumComponents,
72                                const VTableLayout::VTableThunkTy *VTableThunks,
73                                          unsigned NumVTableThunks);
74
75public:
76  CodeGenVTables(CodeGenModule &CGM);
77
78  VTableContext &getVTableContext() { return VTContext; }
79
80  /// \brief True if the VTable of this record must be emitted in the
81  /// translation unit.
82  bool ShouldEmitVTableInThisTU(const CXXRecordDecl *RD);
83
84  /// needsVTTParameter - Return whether the given global decl needs a VTT
85  /// parameter, which it does if it's a base constructor or destructor with
86  /// virtual bases.
87  static bool needsVTTParameter(GlobalDecl GD);
88
89  /// getSubVTTIndex - Return the index of the sub-VTT for the base class of the
90  /// given record decl.
91  uint64_t getSubVTTIndex(const CXXRecordDecl *RD, BaseSubobject Base);
92
93  /// getSecondaryVirtualPointerIndex - Return the index in the VTT where the
94  /// virtual pointer for the given subobject is located.
95  uint64_t getSecondaryVirtualPointerIndex(const CXXRecordDecl *RD,
96                                           BaseSubobject Base);
97
98  /// getAddressPoint - Get the address point of the given subobject in the
99  /// class decl.
100  uint64_t getAddressPoint(BaseSubobject Base, const CXXRecordDecl *RD);
101
102  /// GetAddrOfVTable - Get the address of the vtable for the given record decl.
103  llvm::GlobalVariable *GetAddrOfVTable(const CXXRecordDecl *RD);
104
105  /// EmitVTableDefinition - Emit the definition of the given vtable.
106  void EmitVTableDefinition(llvm::GlobalVariable *VTable,
107                            llvm::GlobalVariable::LinkageTypes Linkage,
108                            const CXXRecordDecl *RD);
109
110  /// GenerateConstructionVTable - Generate a construction vtable for the given
111  /// base subobject.
112  llvm::GlobalVariable *
113  GenerateConstructionVTable(const CXXRecordDecl *RD, const BaseSubobject &Base,
114                             bool BaseIsVirtual,
115                             llvm::GlobalVariable::LinkageTypes Linkage,
116                             VTableAddressPointsMapTy& AddressPoints);
117
118
119  /// GetAddrOfVTable - Get the address of the VTT for the given record decl.
120  llvm::GlobalVariable *GetAddrOfVTT(const CXXRecordDecl *RD);
121
122  /// EmitVTTDefinition - Emit the definition of the given vtable.
123  void EmitVTTDefinition(llvm::GlobalVariable *VTT,
124                         llvm::GlobalVariable::LinkageTypes Linkage,
125                         const CXXRecordDecl *RD);
126
127  /// EmitThunks - Emit the associated thunks for the given global decl.
128  void EmitThunks(GlobalDecl GD);
129
130  /// GenerateClassData - Generate all the class data required to be generated
131  /// upon definition of a KeyFunction.  This includes the vtable, the
132  /// rtti data structure and the VTT.
133  ///
134  /// \param Linkage - The desired linkage of the vtable, the RTTI and the VTT.
135  void GenerateClassData(llvm::GlobalVariable::LinkageTypes Linkage,
136                         const CXXRecordDecl *RD);
137};
138
139} // end namespace CodeGen
140} // end namespace clang
141#endif
142