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//===--- CGCXXRtti.cpp - Emit LLVM Code for C++ RTTI descriptors ----------===//
//
// 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 RTTI descriptors.
//
//===----------------------------------------------------------------------===//
#include "CodeGenModule.h"
using namespace clang;
using namespace CodeGen;
class RttiBuilder {
CodeGenModule &CGM; // Per-module state.
llvm::LLVMContext &VMContext;
const llvm::Type *Int8PtrTy;
public:
RttiBuilder(CodeGenModule &cgm)
: CGM(cgm), VMContext(cgm.getModule().getContext()),
Int8PtrTy(llvm::Type::getInt8PtrTy(VMContext)) { }
llvm::Constant *Buildclass_type_infoDesc() {
// Build a descriptor for class_type_info.
llvm::StringRef Name = "_ZTVN10__cxxabiv121__vmi_class_type_infoE";
llvm::Constant *GV = CGM.getModule().getGlobalVariable(Name);
if (GV)
GV = llvm::ConstantExpr::getBitCast(GV,
llvm::PointerType::get(Int8PtrTy, 0));
else {
llvm::GlobalVariable::LinkageTypes linktype;
linktype = llvm::GlobalValue::ExternalLinkage;
GV = new llvm::GlobalVariable(CGM.getModule(), Int8PtrTy,
true, linktype, 0, Name);
}
llvm::Constant *C;
C = llvm::ConstantInt::get(llvm::Type::getInt64Ty(VMContext), 2);
C = llvm::ConstantExpr::getInBoundsGetElementPtr(GV, &C, 1);
return llvm::ConstantExpr::getBitCast(C, Int8PtrTy);
}
llvm::Constant *BuildName(const CXXRecordDecl *RD) {
llvm::SmallString<256> OutName;
llvm::raw_svector_ostream Out(OutName);
mangleCXXRttiName(CGM.getMangleContext(),
CGM.getContext().getTagDeclType(RD), Out);
llvm::GlobalVariable::LinkageTypes linktype;
linktype = llvm::GlobalValue::LinkOnceODRLinkage;
llvm::Constant *C;
C = llvm::ConstantArray::get(VMContext, Out.str().substr(4));
llvm::Constant *s = new llvm::GlobalVariable(CGM.getModule(), C->getType(),
true, linktype, C,
Out.str());
s = llvm::ConstantExpr::getBitCast(s, Int8PtrTy);
return s;
};
llvm::Constant *Buildclass_type_info(const CXXRecordDecl *RD) {
const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(VMContext);
if (!CGM.getContext().getLangOptions().Rtti)
return llvm::Constant::getNullValue(Int8PtrTy);
llvm::SmallString<256> OutName;
llvm::raw_svector_ostream Out(OutName);
mangleCXXRtti(CGM.getMangleContext(), CGM.getContext().getTagDeclType(RD),
Out);
llvm::GlobalVariable::LinkageTypes linktype;
linktype = llvm::GlobalValue::LinkOnceODRLinkage;
std::vector<llvm::Constant *> info;
info.push_back(Buildclass_type_infoDesc());
info.push_back(BuildName(RD));
// FIXME: rest of rtti bits
llvm::Constant *C;
llvm::ArrayType *type = llvm::ArrayType::get(Int8PtrTy, info.size());
C = llvm::ConstantArray::get(type, info);
llvm::Constant *Rtti =
new llvm::GlobalVariable(CGM.getModule(), type, true, linktype, C,
Out.str());
Rtti = llvm::ConstantExpr::getBitCast(Rtti, Int8PtrTy);
return Rtti;
}
};
llvm::Constant *CodeGenModule::GenerateRtti(const CXXRecordDecl *RD) {
RttiBuilder b(*this);
return b.Buildclass_type_info(RD);
}
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