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

using namespace clang;
using namespace CodeGen;

namespace {
class VtableBuilder {
public:
  /// Index_t - Vtable index type.
  typedef uint64_t Index_t;
  typedef std::vector<std::pair<GlobalDecl,
                                std::pair<GlobalDecl, ThunkAdjustment> > >
      SavedAdjustmentsVectorTy;
private:
  
  // VtableComponents - The components of the vtable being built.
  typedef llvm::SmallVector<llvm::Constant *, 64> VtableComponentsVectorTy;
  VtableComponentsVectorTy VtableComponents;
  
  const bool BuildVtable;

  llvm::Type *Ptr8Ty;
  
  /// MostDerivedClass - The most derived class that this vtable is being 
  /// built for.
  const CXXRecordDecl *MostDerivedClass;
  
  /// 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.
  
  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;
  
  /// VtableMethods - A data structure for keeping track of methods in a vtable.
  /// Can add methods, override methods and iterate in vtable order.
  class VtableMethods {
    // MethodToIndexMap - Maps from a global decl to the index it has in the
    // Methods vector.
    llvm::DenseMap<GlobalDecl, uint64_t> MethodToIndexMap;

    /// Methods - The methods, in vtable order.
    typedef llvm::SmallVector<GlobalDecl, 16> MethodsVectorTy;
    MethodsVectorTy Methods;
    MethodsVectorTy OrigMethods;

  public:
    /// AddMethod - Add a method to the vtable methods.
    void AddMethod(GlobalDecl GD) {
      assert(!MethodToIndexMap.count(GD) && 
             "Method has already been added!");
      
      MethodToIndexMap[GD] = Methods.size();
      Methods.push_back(GD);
      OrigMethods