path: root/lib/CodeGen/CGClass.cpp

//===--- CGClass.cpp - Emit LLVM Code for C++ classes ---------------------===//
//
//                     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 classes
//
//===----------------------------------------------------------------------===//

#include "CodeGenFunction.h"
#include "clang/AST/CXXInheritance.h"
#include "clang/AST/RecordLayout.h"
#include "clang/AST/StmtCXX.h"

using namespace clang;
using namespace CodeGen;

static uint64_t 
ComputeNonVirtualBaseClassOffset(ASTContext &Context, 
                                 const CXXRecordDecl *DerivedClass,
                                 CXXBaseSpecifierArray::iterator Start,
                                 CXXBaseSpecifierArray::iterator End) {
  uint64_t Offset = 0;
  
  const CXXRecordDecl *RD = DerivedClass;
  
  for (CXXBaseSpecifierArray::iterator I = Start; I != End; ++I) {
    const CXXBaseSpecifier *Base = *I;
    assert(!Base->isVirtual() && "Should not see virtual bases here!");

    // Get the layout.
    const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
    
    const CXXRecordDecl *BaseDecl = 
      cast<CXXRecordDecl>(Base->getType()->getAs<RecordType>()->getDecl());
    
    // Add the offset.
    Offset += Layout.getBaseClassOffset(BaseDecl);
    
    RD = BaseDecl;
  }
  
  // FIXME: We should not use / 8 here.
  return Offset / 8;
}

llvm::Constant *
CodeGenModule::GetNonVirtualBaseClassOffset(const CXXRecordDecl *ClassDecl,
                                        const CXXBaseSpecifierArray &BasePath) {
  assert(!BasePath.empty() && "Base path should not be empty!");

  uint64_t Offset = 
    ComputeNonVirtualBaseClassOffset(getContext(), ClassDecl, 
                                     BasePath.begin(), BasePath.end());
  if (!Offset)
    return 0;
  
  const llvm::Type *PtrDiffTy = 
  Types.ConvertType(getContext().getPointerDiffType());
  
  return llvm::ConstantInt::get(PtrDiffTy, Offset);
}