#include "CodeGenTBAA.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/RecordLayout.h"
#include "clang/AST/Mangle.h"
#include "clang/Frontend/CodeGenOptions.h"
#include "llvm/LLVMContext.h"
#include "llvm/Metadata.h"
#include "llvm/Constants.h"
#include "llvm/Type.h"
using namespace clang;
using namespace CodeGen;
CodeGenTBAA::CodeGenTBAA(ASTContext &Ctx, llvm::LLVMContext& VMContext,
const CodeGenOptions &CGO,
const LangOptions &Features, MangleContext &MContext)
: Context(Ctx), CodeGenOpts(CGO), Features(Features), MContext(MContext),
MDHelper(VMContext), Root(0), Char(0) {
}
CodeGenTBAA::~CodeGenTBAA() {
}
llvm::MDNode *CodeGenTBAA::getRoot() {
if (!Root)
Root = MDHelper.createTBAARoot("Simple C/C++ TBAA");
return Root;
}
llvm::MDNode *CodeGenTBAA::getChar() {
if (!Char)
Char = MDHelper.createTBAANode("omnipotent char", getRoot());
return Char;
}
static bool TypeHasMayAlias(QualType QTy) {
if (const TagType *TTy = dyn_cast<TagType>(QTy))
return TTy->getDecl()->hasAttr<MayAliasAttr>();
if (const TypedefType *TTy = dyn_cast<TypedefType>(QTy)) {
if (TTy->getDecl()->hasAttr<MayAliasAttr>())
return true;
return TypeHasMayAlias(TTy->desugar());
}
return false;
}
llvm::MDNode *
CodeGenTBAA::getTBAAInfo(QualType QTy) {
if (CodeGenOpts.OptimizationLevel == 0 || CodeGenOpts.RelaxedAliasing)
return NULL;
if (TypeHasMayAlias(QTy))
return getChar();
const Type *Ty = Context.getCanonicalType(QTy).getTypePtr();
if (llvm::MDNode *N = MetadataCache[Ty])
return N;
if (const BuiltinType *BTy = dyn_cast<BuiltinType>(Ty)) {
switch (BTy->getKind()) {
case BuiltinType::Char_U:
case BuiltinType::Char_S:
case BuiltinType::UChar:
case BuiltinType::SChar:
return getChar();
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);
default:
return MetadataCache[Ty] =
MDHelper.createTBAANode(BTy->getName(Features), getChar());
}
}
if (Ty->isPointerType())
return MetadataCache[Ty] = MDHelper.createTBAANode("any pointer",
getChar());
if (const EnumType *ETy = dyn_cast<EnumType>(Ty)) {
if (!Features.CPlusPlus &&
ETy->getDecl()->getTypedefNameForAnonDecl())
return MetadataCache[Ty] = getChar();
if (Features.CPlusPlus &&
ETy->getDecl()->getLinkage() != ExternalLinkage)
return MetadataCache[Ty] = getChar();
SmallString<256> OutName;
llvm::raw_svector_ostream Out(OutName);
MContext.mangleCXXRTTIName(QualType(ETy, 0), Out);
Out.flush();
return MetadataCache[Ty] = MDHelper.createTBAANode(OutName, getChar());
}
return MetadataCache[Ty] = getChar();
}
llvm::MDNode *CodeGenTBAA::getTBAAInfoForVTablePtr() {
return MDHelper.createTBAANode("vtable pointer", getRoot());
}
bool
CodeGenTBAA::CollectFields(uint64_t BaseOffset,
QualType QTy,
SmallVectorImpl<llvm::MDBuilder::TBAAStructField> &
Fields,
bool MayAlias) {
if (const RecordType *TTy = QTy->getAs<RecordType>()) {
const RecordDecl *RD = TTy->getDecl()->getDefinition();
if (RD->hasFlexibleArrayMember())
return false;
if (const CXXRecordDecl *Decl = dyn_cast<CXXRecordDecl>(RD))
if (Decl->bases_begin() != Decl->bases_end())
return false;
const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
unsigned idx = 0;
for (RecordDecl::field_iterator i = RD->field_begin(),
e = RD->field_end(); i != e; ++i, ++idx) {
uint64_t Offset = BaseOffset +
Layout.getFieldOffset(idx) / Context.getCharWidth();
QualType FieldQTy = i->getType();
if (!CollectFields(Offset, FieldQTy, Fields,
MayAlias || TypeHasMayAlias(FieldQTy)))
return false;
}
return true;
}
uint64_t Offset = BaseOffset;
uint64_t Size = Context.getTypeSizeInChars(QTy).getQuantity();
llvm::MDNode *TBAAInfo = MayAlias ? getChar() : getTBAAInfo(QTy);
Fields.push_back(llvm::MDBuilder::TBAAStructField(Offset, Size, TBAAInfo));
return true;
}
llvm::MDNode *
CodeGenTBAA::getTBAAStructInfo(QualType QTy) {
const Type *Ty = Context.getCanonicalType(QTy).getTypePtr();
if (llvm::MDNode *N = StructMetadataCache[Ty])
return N;
SmallVector<llvm::MDBuilder::TBAAStructField, 4> Fields;
if (CollectFields(0, QTy, Fields, TypeHasMayAlias(QTy)))
return MDHelper.createTBAAStructNode(Fields);
return StructMetadataCache[Ty] = NULL;
}