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//===--- CGCXXClass.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/RecordLayout.h"
using namespace clang;
using namespace CodeGen;
static bool
GetNestedPaths(llvm::SmallVectorImpl<const CXXRecordDecl *> &NestedBasePaths,
const CXXRecordDecl *ClassDecl,
const CXXRecordDecl *BaseClassDecl) {
for (CXXRecordDecl::base_class_const_iterator i = ClassDecl->bases_begin(),
e = ClassDecl->bases_end(); i != e; ++i) {
if (i->isVirtual())
continue;
const CXXRecordDecl *Base =
cast<CXXRecordDecl>(i->getType()->getAs<RecordType>()->getDecl());
if (Base == BaseClassDecl) {
NestedBasePaths.push_back(BaseClassDecl);
return true;
}
}
// BaseClassDecl not an immediate base of ClassDecl.
for (CXXRecordDecl::base_class_const_iterator i = ClassDecl->bases_begin(),
e = ClassDecl->bases_end(); i != e; ++i) {
if (i->isVirtual())
continue;
const CXXRecordDecl *Base =
cast<CXXRecordDecl>(i->getType()->getAs<RecordType>()->getDecl());
if (GetNestedPaths(NestedBasePaths, Base, BaseClassDecl)) {
NestedBasePaths.push_back(Base);
return true;
}
}
return false;
}
static uint64_t ComputeBaseClassOffset(ASTContext &Context,
const CXXRecordDecl *ClassDecl,
const CXXRecordDecl *BaseClassDecl) {
uint64_t Offset = 0;
llvm::SmallVector<const CXXRecordDecl *, 16> NestedBasePaths;
GetNestedPaths(NestedBasePaths, ClassDecl, BaseClassDecl);
assert(NestedBasePaths.size() > 0 &&
"AddressCXXOfBaseClass - inheritence path failed");
NestedBasePaths.push_back(ClassDecl);
for (unsigned i = NestedBasePaths.size() - 1; i > 0; i--) {
const CXXRecordDecl *DerivedClass = NestedBasePaths[i];
const CXXRecordDecl *BaseClass = NestedBasePaths[i-1];
const ASTRecordLayout &Layout =
Context.getASTRecordLayout(DerivedClass);
Offset += Layout.getBaseClassOffset(BaseClass) / 8;
}
return Offset;
}
llvm::Value *
CodeGenFunction::GetAddressCXXOfBaseClass(llvm::Value *BaseValue,
const CXXRecordDecl *ClassDecl,
const CXXRecordDecl *BaseClassDecl,
bool NullCheckValue) {
if (ClassDecl == BaseClassDecl)
return BaseValue;
uint64_t Offset = ComputeBaseClassOffset(getContext(),
ClassDecl, BaseClassDecl);
const llvm::Type *LongTy =
CGM.getTypes().ConvertType(CGM.getContext().LongTy);
const llvm::Type *Int8PtrTy =
llvm::PointerType::getUnqual(llvm::Type::getInt8Ty(VMContext));
llvm::Value *OffsetVal = llvm::ConstantInt::get(LongTy, Offset);
// Apply the offset.
BaseValue = Builder.CreateBitCast(BaseValue, Int8PtrTy);
BaseValue = Builder.CreateGEP(BaseValue, OffsetVal, "add.ptr");
QualType BTy =
getContext().getCanonicalType(
getContext().getTypeDeclType(const_cast<CXXRecordDecl*>(BaseClassDecl)));
// Cast back.
const llvm::Type *BasePtr = llvm::PointerType::getUnqual(ConvertType(BTy));
BaseValue = Builder.CreateBitCast(BaseValue, BasePtr);
return BaseValue;
}
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