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      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   /// emitThunk - Emit a single thunk.
     53   void emitThunk(GlobalDecl GD, const ThunkInfo &Thunk, bool ForVTable);
     54 
     55   /// maybeEmitThunkForVTable - Emit the given thunk for the vtable if needed by
     56   /// the ABI.
     57   void maybeEmitThunkForVTable(GlobalDecl GD, const ThunkInfo &Thunk);
     58 
     59 public:
     60   /// CreateVTableInitializer - Create a vtable initializer for the given record
     61   /// decl.
     62   /// \param Components - The vtable components; this is really an array of
     63   /// VTableComponents.
     64   llvm::Constant *CreateVTableInitializer(
     65       const CXXRecordDecl *RD, const VTableComponent *Components,
     66       unsigned NumComponents, const VTableLayout::VTableThunkTy *VTableThunks,
     67       unsigned NumVTableThunks, llvm::Constant *RTTI);
     68 
     69   CodeGenVTables(CodeGenModule &CGM);
     70 
     71   ItaniumVTableContext &getItaniumVTableContext() {
     72     return *cast<ItaniumVTableContext>(VTContext);
     73   }
     74 
     75   MicrosoftVTableContext &getMicrosoftVTableContext() {
     76     return *cast<MicrosoftVTableContext>(VTContext);
     77   }
     78 
     79   /// getSubVTTIndex - Return the index of the sub-VTT for the base class of the
     80   /// given record decl.
     81   uint64_t getSubVTTIndex(const CXXRecordDecl *RD, BaseSubobject Base);
     82 
     83   /// getSecondaryVirtualPointerIndex - Return the index in the VTT where the
     84   /// virtual pointer for the given subobject is located.
     85   uint64_t getSecondaryVirtualPointerIndex(const CXXRecordDecl *RD,
     86                                            BaseSubobject Base);
     87 
     88   /// GenerateConstructionVTable - Generate a construction vtable for the given
     89   /// base subobject.
     90   llvm::GlobalVariable *
     91   GenerateConstructionVTable(const CXXRecordDecl *RD, const BaseSubobject &Base,
     92                              bool BaseIsVirtual,
     93                              llvm::GlobalVariable::LinkageTypes Linkage,
     94                              VTableAddressPointsMapTy& AddressPoints);
     95 
     96 
     97   /// GetAddrOfVTT - Get the address of the VTT for the given record decl.
     98   llvm::GlobalVariable *GetAddrOfVTT(const CXXRecordDecl *RD);
     99 
    100   /// EmitVTTDefinition - Emit the definition of the given vtable.
    101   void EmitVTTDefinition(llvm::GlobalVariable *VTT,
    102                          llvm::GlobalVariable::LinkageTypes Linkage,
    103                          const CXXRecordDecl *RD);
    104 
    105   /// EmitThunks - Emit the associated thunks for the given global decl.
    106   void EmitThunks(GlobalDecl GD);
    107 
    108   /// GenerateClassData - Generate all the class data required to be
    109   /// generated upon definition of a KeyFunction.  This includes the
    110   /// vtable, the RTTI data structure (if RTTI is enabled) and the VTT
    111   /// (if the class has virtual bases).
    112   void GenerateClassData(const CXXRecordDecl *RD);
    113 
    114   bool isVTableExternal(const CXXRecordDecl *RD);
    115 };
    116 
    117 } // end namespace CodeGen
    118 } // end namespace clang
    119 #endif
    120