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//===--- CodeGenTypes.cpp - TBAA information for LLVM CodeGen -------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This is the code that manages TBAA information.
//
//===----------------------------------------------------------------------===//
#include "CodeGenTBAA.h"
#include "clang/AST/ASTContext.h"
#include "llvm/LLVMContext.h"
#include "llvm/Metadata.h"
using namespace clang;
using namespace CodeGen;
CodeGenTBAA::CodeGenTBAA(ASTContext &Ctx, llvm::LLVMContext& VMContext,
const LangOptions &Features)
: Context(Ctx), VMContext(VMContext), Features(Features), Root(0), Char(0) {
}
CodeGenTBAA::~CodeGenTBAA() {
}
llvm::MDNode *CodeGenTBAA::getTBAAInfoForNamedType(const char *NameStr,
llvm::MDNode *Parent) {
llvm::Value *Ops[] = {
llvm::MDString::get(VMContext, NameStr),
Parent
};
return llvm::MDNode::get(VMContext, Ops, llvm::array_lengthof(Ops));
}
llvm::MDNode *
CodeGenTBAA::getTBAAInfo(QualType QTy) {
Type *Ty = Context.getCanonicalType(QTy).getTypePtr();
if (llvm::MDNode *N = MetadataCache[Ty])
return N;
if (!Root) {
Root = getTBAAInfoForNamedType("Experimental TBAA", 0);
Char = getTBAAInfoForNamedType("omnipotent char", Root);
}
// For now, just emit a very minimal tree.
if (const BuiltinType *BTy = dyn_cast<BuiltinType>(Ty)) {
switch (BTy->getKind()) {
// Charactar types are special and can alias anything.
case BuiltinType::Char_U:
case BuiltinType::Char_S:
case BuiltinType::UChar:
case BuiltinType::SChar:
return Char;
// Unsigned types can alias their corresponding signed types.
case BuiltinType::UShort:
return getTBAAInfo(Context.ShortTy);
case BuiltinType::UInt:
return getTBAAInfo(Context.IntTy);
case BuiltinType::ULong:
return getTBAAInfo(Context.LongTy);
case BuiltinType::ULongLong:
return getTBAAInfo(Context.LongLongTy);
case BuiltinType::UInt128:
return getTBAAInfo(Context.Int128Ty);
// Other builtin types.
default:
return MetadataCache[Ty] =
getTBAAInfoForNamedType(BTy->getName(Features), Char);
}
}
// For now, treat all pointers as equivalent to each other.
if (Ty->isPointerType())
return MetadataCache[Ty] = getTBAAInfoForNamedType("TBAA.pointer", Char);
// For now, handle any other kind of type conservatively.
return MetadataCache[Ty] = Char;
}
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