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   class ConstantArrayBuilder;
31   class ConstantStructBuilder;
32 
33 class CodeGenVTables {
34   CodeGenModule &CGM;
35 
36   VTableContextBase *VTContext;
37 
38   /// VTableAddressPointsMapTy - Address points for a single vtable.
39   typedef VTableLayout::AddressPointsMapTy VTableAddressPointsMapTy;
40 
41   typedef std::pair<const CXXRecordDecl *, BaseSubobject> BaseSubobjectPairTy;
42   typedef llvm::DenseMap<BaseSubobjectPairTy, uint64_t> SubVTTIndiciesMapTy;
43 
44   /// SubVTTIndicies - Contains indices into the various sub-VTTs.
45   SubVTTIndiciesMapTy SubVTTIndicies;
46 
47   typedef llvm::DenseMap<BaseSubobjectPairTy, uint64_t>
48     SecondaryVirtualPointerIndicesMapTy;
49 
50   /// SecondaryVirtualPointerIndices - Contains the secondary virtual pointer
51   /// indices.
52   SecondaryVirtualPointerIndicesMapTy SecondaryVirtualPointerIndices;
53 
54   /// Cache for the pure virtual member call function.
55   llvm::Constant *PureVirtualFn = nullptr;
56 
57   /// Cache for the deleted virtual member call function.
58   llvm::Constant *DeletedVirtualFn = nullptr;
59 
60   /// Get the address of a thunk and emit it if necessary.
61   llvm::Constant *maybeEmitThunk(GlobalDecl GD,
62                                  const ThunkInfo &ThunkAdjustments,
63                                  bool ForVTable);
64 
65   void addVTableComponent(ConstantArrayBuilder &builder,
66                           const VTableLayout &layout, unsigned idx,
67                           llvm::Constant *rtti,
68                           unsigned &nextVTableThunkIndex);
69 
70 public:
71   /// Add vtable components for the given vtable layout to the given
72   /// global initializer.
73   void createVTableInitializer(ConstantStructBuilder &builder,
74                                const VTableLayout &layout,
75                                llvm::Constant *rtti);
76 
77   CodeGenVTables(CodeGenModule &CGM);
78 
79   ItaniumVTableContext &getItaniumVTableContext() {
80     return *cast<ItaniumVTableContext>(VTContext);
81   }
82 
83   MicrosoftVTableContext &getMicrosoftVTableContext() {
84     return *cast<MicrosoftVTableContext>(VTContext);
85   }
86 
87   /// getSubVTTIndex - Return the index of the sub-VTT for the base class of the
88   /// given record decl.
89   uint64_t getSubVTTIndex(const CXXRecordDecl *RD, BaseSubobject Base);
90 
91   /// getSecondaryVirtualPointerIndex - Return the index in the VTT where the
92   /// virtual pointer for the given subobject is located.
93   uint64_t getSecondaryVirtualPointerIndex(const CXXRecordDecl *RD,
94                                            BaseSubobject Base);
95 
96   /// GenerateConstructionVTable - Generate a construction vtable for the given
97   /// base subobject.
98   llvm::GlobalVariable *
99   GenerateConstructionVTable(const CXXRecordDecl *RD, const BaseSubobject &Base,
100                              bool BaseIsVirtual,
101                              llvm::GlobalVariable::LinkageTypes Linkage,
102                              VTableAddressPointsMapTy& AddressPoints);
103 
104 
105   /// GetAddrOfVTT - Get the address of the VTT for the given record decl.
106   llvm::GlobalVariable *GetAddrOfVTT(const CXXRecordDecl *RD);
107 
108   /// EmitVTTDefinition - Emit the definition of the given vtable.
109   void EmitVTTDefinition(llvm::GlobalVariable *VTT,
110                          llvm::GlobalVariable::LinkageTypes Linkage,
111                          const CXXRecordDecl *RD);
112 
113   /// EmitThunks - Emit the associated thunks for the given global decl.
114   void EmitThunks(GlobalDecl GD);
115 
116   /// GenerateClassData - Generate all the class data required to be
117   /// generated upon definition of a KeyFunction.  This includes the
118   /// vtable, the RTTI data structure (if RTTI is enabled) and the VTT
119   /// (if the class has virtual bases).
120   void GenerateClassData(const CXXRecordDecl *RD);
121 
122   bool isVTableExternal(const CXXRecordDecl *RD);
123 
124   /// Returns the type of a vtable with the given layout. Normally a struct of
125   /// arrays of pointers, with one struct element for each vtable in the vtable
126   /// group.
127   llvm::Type *getVTableType(const VTableLayout &layout);
128 };
129 
130 } // end namespace CodeGen
131 } // end namespace clang
132 #endif
133