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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"
#include "clang/AST/RecordLayout.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)) { }
/// BuildVtableRef - Build a reference to a vtable.
llvm::Constant *BuildVtableRef(const char *Name) {
// Build a descriptor for Name
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;
};
/// - BuildFlags - Build a psABI __flags value for __vmi_class_type_info.
llvm::Constant *BuildFlags(int f) {
return llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext), f);
}
/// BuildBaseCount - Build a psABI __base_count value for
/// __vmi_class_type_info.
llvm::Constant *BuildBaseCount(unsigned c) {
return llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext), c);
}
llvm::Constant *Buildclass_type_infoRef(const CXXRecordDecl *RD) {
const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(VMContext);
llvm::Constant *C;
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);
C = CGM.getModule().getGlobalVariable(Out.str());
if (C)
return llvm::ConstantExpr::getBitCast(C, Int8PtrTy);
llvm::GlobalVariable::LinkageTypes linktype;
linktype = llvm::GlobalValue::ExternalLinkage;;
C = new llvm::GlobalVariable(CGM.getModule(), Int8PtrTy, true, linktype,
0, Out.str());
return llvm::ConstantExpr::getBitCast(C, Int8PtrTy);
}
llvm::Constant *Buildclass_type_info(const CXXRecordDecl *RD) {
const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(VMContext);
llvm::Constant *C;
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 *GV;
GV = CGM.getModule().getGlobalVariable(Out.str());
if (GV && !GV->isDeclaration())
return llvm::ConstantExpr::getBitCast(GV, Int8PtrTy);
llvm::GlobalVariable::LinkageTypes linktype;
linktype = llvm::GlobalValue::LinkOnceODRLinkage;
std::vector<llvm::Constant *> info;
if (RD->getNumBases() == 0)
C = BuildVtableRef("_ZTVN10__cxxabiv117__class_type_infoE");
// FIXME: Add si_class_type_info optimization
else
C = BuildVtableRef("_ZTVN10__cxxabiv121__vmi_class_type_infoE");
info.push_back(C);
info.push_back(BuildName(RD));
// If we have no bases, there are no more fields.
if (RD->getNumBases()) {
// FIXME: Calculate is_diamond and non-diamond repeated inheritance, 3 is
// conservative.
info.push_back(BuildFlags(3));
info.push_back(BuildBaseCount(RD->getNumBases()));
const ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(RD);
for (CXXRecordDecl::base_class_const_iterator i = RD->bases_begin(),
e = RD->bases_end(); i != e; ++i) {
const CXXRecordDecl *Base =
cast<CXXRecordDecl>(i->getType()->getAs<RecordType>()->getDecl());
info.push_back(CGM.GenerateRtti(Base));
int64_t offset;
if (!i->isVirtual())
offset = Layout.getBaseClassOffset(Base);
else
offset = CGM.getVtableInfo().getVirtualBaseOffsetIndex(RD, Base);
offset <<= 8;
// Now set the flags.
offset += i->isVirtual() ? 1 : 0;;
offset += i->getAccessSpecifier() == AS_public ? 2 : 0;
const llvm::Type *LongTy =
CGM.getTypes().ConvertType(CGM.getContext().LongTy);
C = llvm::ConstantInt::get(LongTy, offset);
info.push_back(C);
}
}
std::vector<const llvm::Type *> Types(info.size());
for (unsigned i=0; i<info.size(); ++i)
Types[i] = info[i]->getType();
// llvm::StructType *Ty = llvm::StructType::get(VMContext, Types, true);
C = llvm::ConstantStruct::get(VMContext, &info[0], info.size(), false);
if (GV == 0)
GV = new llvm::GlobalVariable(CGM.getModule(), C->getType(), true, linktype,
C, Out.str());
else {
llvm::GlobalVariable *OGV = GV;
GV = new llvm::GlobalVariable(CGM.getModule(), C->getType(), true, linktype,
C, Out.str());
GV->takeName(OGV);
llvm::Constant *NewPtr = llvm::ConstantExpr::getBitCast(GV, OGV->getType());
OGV->replaceAllUsesWith(NewPtr);
OGV->eraseFromParent();
}
return llvm::ConstantExpr::getBitCast(GV, Int8PtrTy);
#if 0
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;
#endif
}
};
llvm::Constant *CodeGenModule::GenerateRttiRef(const CXXRecordDecl *RD) {
RttiBuilder b(*this);
return b.Buildclass_type_infoRef(RD);
}
llvm::Constant *CodeGenModule::GenerateRtti(const CXXRecordDecl *RD) {
RttiBuilder b(*this);
return b.Buildclass_type_info(RD);
}
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