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 LLVM_CLANG_LIB_CODEGEN_CGVTABLES_H
15 #define LLVM_CLANG_LIB_CODEGEN_CGVTABLES_H
16 
17 #include "clang/AST/BaseSubobject.h"
18 #include "clang/AST/CharUnits.h"
19 #include "clang/AST/GlobalDecl.h"
20 #include "clang/AST/VTableBuilder.h"
21 #include "clang/Basic/ABI.h"
22 #include "llvm/ADT/DenseMap.h"
23 #include "llvm/IR/GlobalVariable.h"
24 
25 namespace clang {
26   class CXXRecordDecl;
27 
28 namespace CodeGen {
29   class CodeGenModule;
30 
31 class CodeGenVTables {
32   CodeGenModule &CGM;
33 
34   VTableContextBase *VTContext;
35 
36   /// VTableAddressPointsMapTy - Address points for a single vtable.
37   typedef llvm::DenseMap<BaseSubobject, uint64_t> VTableAddressPointsMapTy;
38 
39   typedef std::pair<const CXXRecordDecl *, BaseSubobject> BaseSubobjectPairTy;
40   typedef llvm::DenseMap<BaseSubobjectPairTy, uint64_t> SubVTTIndiciesMapTy;
41 
42   /// SubVTTIndicies - Contains indices into the various sub-VTTs.
43   SubVTTIndiciesMapTy SubVTTIndicies;
44 
45   typedef llvm::DenseMap<BaseSubobjectPairTy, uint64_t>
46     SecondaryVirtualPointerIndicesMapTy;
47 
48   /// SecondaryVirtualPointerIndices - Contains the secondary virtual pointer
49   /// indices.
50   SecondaryVirtualPointerIndicesMapTy SecondaryVirtualPointerIndices;
51 
52   /// Cache for the pure virtual member call function.
53   llvm::Constant *PureVirtualFn = nullptr;
54 
55   /// Cache for the deleted virtual member call function.
56   llvm::Constant *DeletedVirtualFn = nullptr;
57 
58   /// emitThunk - Emit a single thunk.
59   void emitThunk(GlobalDecl GD, const ThunkInfo &Thunk, bool ForVTable);
60 
61   /// maybeEmitThunkForVTable - Emit the given thunk for the vtable if needed by
62   /// the ABI.
63   void maybeEmitThunkForVTable(GlobalDecl GD, const ThunkInfo &Thunk);
64 
65   llvm::Constant *CreateVTableComponent(unsigned Idx,
66                                         const VTableLayout &VTLayout,
67                                         llvm::Constant *RTTI,
68                                         unsigned &NextVTableThunkIndex);
69 
70 public:
71   /// CreateVTableInitializer - Create a vtable initializer with the given
72   /// layout.
73   llvm::Constant *CreateVTableInitializer(const VTableLayout &VTLayout,
74                                           llvm::Constant *RTTI);
75 
76   CodeGenVTables(CodeGenModule &CGM);
77 
78   ItaniumVTableContext &getItaniumVTableContext() {
79     return *cast<ItaniumVTableContext>(VTContext);
80   }
81 
82   MicrosoftVTableContext &getMicrosoftVTableContext() {
83     return *cast<MicrosoftVTableContext>(VTContext);
84   }
85 
86   /// getSubVTTIndex - Return the index of the sub-VTT for the base class of the
87   /// given record decl.
88   uint64_t getSubVTTIndex(const CXXRecordDecl *RD, BaseSubobject Base);
89 
90   /// getSecondaryVirtualPointerIndex - Return the index in the VTT where the
91   /// virtual pointer for the given subobject is located.
92   uint64_t getSecondaryVirtualPointerIndex(const CXXRecordDecl *RD,
93                                            BaseSubobject Base);
94 
95   /// GenerateConstructionVTable - Generate a construction vtable for the given
96   /// base subobject.
97   llvm::GlobalVariable *
98   GenerateConstructionVTable(const CXXRecordDecl *RD, const BaseSubobject &Base,
99                              bool BaseIsVirtual,
100                              llvm::GlobalVariable::LinkageTypes Linkage,
101                              VTableAddressPointsMapTy& AddressPoints);
102 
103 
104   /// GetAddrOfVTT - Get the address of the VTT for the given record decl.
105   llvm::GlobalVariable *GetAddrOfVTT(const CXXRecordDecl *RD);
106 
107   /// EmitVTTDefinition - Emit the definition of the given vtable.
108   void EmitVTTDefinition(llvm::GlobalVariable *VTT,
109                          llvm::GlobalVariable::LinkageTypes Linkage,
110                          const CXXRecordDecl *RD);
111 
112   /// EmitThunks - Emit the associated thunks for the given global decl.
113   void EmitThunks(GlobalDecl GD);
114 
115   /// GenerateClassData - Generate all the class data required to be
116   /// generated upon definition of a KeyFunction.  This includes the
117   /// vtable, the RTTI data structure (if RTTI is enabled) and the VTT
118   /// (if the class has virtual bases).
119   void GenerateClassData(const CXXRecordDecl *RD);
120 
121   bool isVTableExternal(const CXXRecordDecl *RD);
122 };
123 
124 } // end namespace CodeGen
125 } // end namespace clang
126 #endif
127