path: root/lib/CodeGen/CGVtable.cpp

//===--- CGVtable.cpp - Emit LLVM Code for C++ vtables --------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This contains code dealing with C++ code generation of virtual tables.
//
//===----------------------------------------------------------------------===//

#include "CodeGenModule.h"
#include "CodeGenFunction.h"

#include "clang/AST/RecordLayout.h"
#include "llvm/ADT/DenseSet.h"
#include <cstdio>

using namespace clang;
using namespace CodeGen;

class VtableBuilder {
public:
  /// Index_t - Vtable index type.
  typedef uint64_t Index_t;
private:
  std::vector<llvm::Constant *> &methods;
  std::vector<llvm::Constant *> submethods;
  llvm::Type *Ptr8Ty;
  /// Class - The most derived class that this vtable is being built for.
  const CXXRecordDecl *Class;
  /// LayoutClass - The most derived class used for virtual base layout
  /// information.
  const CXXRecordDecl *LayoutClass;
  /// LayoutOffset - The offset for Class in LayoutClass.
  uint64_t LayoutOffset;
  /// BLayout - Layout for the most derived class that this vtable is being
  /// built for.
  const ASTRecordLayout &BLayout;
  llvm::SmallSet<const CXXRecordDecl *, 32> IndirectPrimary;
  llvm::SmallSet<const CXXRecordDecl *, 32> SeenVBase;
  llvm::Constant *rtti;
  llvm::LLVMContext &VMContext;
  CodeGenModule &CGM;  // Per-module state.
  /// Index - Maps a method decl into a vtable index.  Useful for virtual
  /// dispatch codegen.
  llvm::DenseMap<GlobalDecl, Index_t> Index;
  llvm::DenseMap<GlobalDecl, Index_t> VCall;
  llvm::DenseMap<GlobalDecl, Index_t> VCallOffset;
  // This is the offset to the nearest virtual base
  llvm::DenseMap<GlobalDecl, Index_t> NonVirtualOffset;
  llvm::DenseMap<const CXXRecordDecl *, Index_t> VBIndex;

  /// PureVirtualFunction - Points to __cxa_pure_virtual.
  llvm::Constant *PureVirtualFn;
  
  /// Thunk - Represents a single thunk.
  struct Thunk {
    Thunk()
      : Index(0) { }
    
    Thunk(uint64_t Index, const ThunkAdjustment &Adjustment)
      : Index(Index), Adjustment(Adjustment) { }
    
    /// Index - The index in the vtable.
    uint64_t Index;
    
    /// Adjustment - The thunk adjustment.
    ThunkAdjustment Adjustment;
  };

  /// Thunks - The thunks in a vtable.
  typedef llvm::DenseMap<GlobalDecl, Thunk> ThunksMapTy;
  ThunksMapTy Thunks;

  /// CovariantThunk - Represents a single covariant thunk.
  struct CovariantThunk {
    CovariantThunk()
      : Index(0) { }
    
    CovariantThunk(uint64_t Index, const ThunkAdjustment &ThisAdjustment,
                   const ThunkAdjustment &ReturnAdjustment, 
                   CanQualType ReturnType) 
      : Index(Index), Adjustment(ThisAdjustment, ReturnAdjustment), 
      ReturnType(ReturnType) { }
    
    // Index - The index in the vtable.
    uint64_t Index;
    
    /// Adjustment - The covariant thunk adjustment.
    CovariantThunkAdjustment Adjustment;
    
    /// ReturnType - The return type of the function.
    CanQualType ReturnType;
  };
  
  /// CovariantThunks - The covariant thunks in a vtable.
  typedef llvm::DenseMap<GlobalDecl, CovariantThunk> CovariantThunksMapTy;
  CovariantThunksMapTy CovariantThunks;
  
  /// PureVirtualMethods - Pure virtual methods.
  typedef llvm::DenseSet<GlobalDecl> PureVirtualMethodsSetTy;
  PureVirtualMethodsSetTy PureVirtualMethods;

  std::vector<Index_t> VCalls;

  typedef std::pair<const CXXRecordDecl *, uint64_t> CtorVtable_t;
  // subAddressPoints - Used to hold the AddressPoints (offsets) into the built
  // vtable for use in computing the initializers for the VTT.
  llvm::DenseMap<CtorVtable_t, int64_t> &subAddressPoints;

  typedef CXXRecordDecl::method_iterator method_iter;
  const bool Extern;
  const