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clang-1/lib/CodeGen/CodeGenTypes.cpp

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//===--- CodeGenTypes.cpp - Type translation 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 handles AST -> LLVM type lowering.
//
//===----------------------------------------------------------------------===//
#include "CodeGenTypes.h"
#include "CGCall.h"
#include "CGCXXABI.h"
#include "CGRecordLayout.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/DeclObjC.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/Expr.h"
#include "clang/AST/RecordLayout.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Module.h"
#include "llvm/Target/TargetData.h"
using namespace clang;
using namespace CodeGen;
CodeGenTypes::CodeGenTypes(ASTContext &Ctx, llvm::Module& M,
const llvm::TargetData &TD, const ABIInfo &Info,
CGCXXABI &CXXABI, const CodeGenOptions &CGO)
: Context(Ctx), Target(Ctx.getTargetInfo()), TheModule(M), TheTargetData(TD),
TheABIInfo(Info), TheCXXABI(CXXABI), CodeGenOpts(CGO) {
SkippedLayout = false;
}
CodeGenTypes::~CodeGenTypes() {
for (llvm::DenseMap<const Type *, CGRecordLayout *>::iterator
I = CGRecordLayouts.begin(), E = CGRecordLayouts.end();
I != E; ++I)
delete I->second;
for (llvm::FoldingSet<CGFunctionInfo>::iterator
I = FunctionInfos.begin(), E = FunctionInfos.end(); I != E; )
delete &*I++;
}
void CodeGenTypes::addRecordTypeName(const RecordDecl *RD,
llvm::StructType *Ty,
StringRef suffix) {
llvm::SmallString<256> TypeName;
llvm::raw_svector_ostream OS(TypeName);
OS << RD->getKindName() << '.';
// Name the codegen type after the typedef name
// if there is no tag type name available
if (RD->getIdentifier()) {
// FIXME: We should not have to check for a null decl context here.
// Right now we do it because the implicit Obj-C decls don't have one.
if (RD->getDeclContext())
OS << RD->getQualifiedNameAsString();
else
RD->printName(OS);
} else if (const TypedefNameDecl *TDD = RD->getTypedefNameForAnonDecl()) {
// FIXME: We should not have to check for a null decl context here.
// Right now we do it because the implicit Obj-C decls don't have one.
if (TDD->getDeclContext())
OS << TDD->getQualifiedNameAsString();
else
TDD->printName(OS);
} else
OS << "anon";
if (!suffix.empty())
OS << suffix;
Ty->setName(OS.str());
}
/// ConvertTypeForMem - Convert type T into a llvm::Type. This differs from
/// ConvertType in that it is used to convert to the memory representation for
/// a type. For example, the scalar representation for _Bool is i1, but the
/// memory representation is usually i8 or i32, depending on the target.
llvm::Type *CodeGenTypes::ConvertTypeForMem(QualType T){
llvm::Type *R = ConvertType(T);
// If this is a non-bool type, don't map it.
if (!R->isIntegerTy(1))
return R;
// Otherwise, return an integer of the target-specified size.
return llvm::IntegerType::get(getLLVMContext(),
(unsigned)Context.getTypeSize(T));
}
/// isRecordLayoutComplete - Return true if the specified type is already
/// completely laid out.
bool CodeGenTypes::isRecordLayoutComplete(const Type *Ty) const {
llvm::DenseMap<const Type*, llvm::StructType *>::const_iterator I =
RecordDeclTypes.find(Ty);
return I != RecordDeclTypes.end() && !I->second->isOpaque();
}
static bool
isSafeToConvert(QualType T, CodeGenTypes &CGT,
llvm::SmallPtrSet<const RecordDecl*, 16> &AlreadyChecked);
/// isSafeToConvert - Return true if it is safe to convert the specified record
/// decl to IR and lay it out, false if doing so would cause us to get into a
/// recursive compilation mess.
static bool
isSafeToConvert(const RecordDecl *RD, CodeGenTypes &CGT,
llvm::SmallPtrSet<const RecordDecl*, 16> &AlreadyChecked) {
// If we have already checked this type (maybe the same type is used by-value
// multiple times in multiple structure fields, don't check again.
if (!AlreadyChecked.insert(RD)) return true;
const Type *Key = CGT.getContext().getTagDeclType(RD).getTypePtr();
// If this type is already laid out, converting it is a noop.
if (CGT.isRecordLayoutComplete(Key)) return true;
// If this type is currently being laid out, we can't recursively compile it.
if (CGT.isRecordBeingLaidOut(Key))
return false;
// If this type would require laying out bases that are currently being laid
// out, don't do it. This includes virtual base classes which get laid out
// when a class is translated, even though they aren't embedded by-value into
// the class.
if (const CXXRecordDecl *CRD = dyn_cast<CXXRecordDecl>(RD)) {
for (CXXRecordDecl::base_class_const_iterator I = CRD->bases_begin(),
E = CRD->bases_end(); I != E; ++I)
if (!isSafeToConvert(I->getType()->getAs<RecordType>()->getDecl(),
CGT, AlreadyChecked))
return false;
}
// If this type would require laying out members that are currently being laid
// out, don't do it.
for (RecordDecl::field_iterator I = RD->field_begin(),
E = RD->field_end(); I != E; ++I)
if (!isSafeToConvert(I->getType(), CGT, AlreadyChecked))
return false;
// If there are no problems, lets do it.
return true;
}
/// isSafeToConvert - Return true if it is safe to convert this field type,
/// which requires the structure elements contained by-value to all be
/// recursively safe to convert.
static bool
isSafeToConvert(QualType T, CodeGenTypes &CGT,
llvm::SmallPtrSet<const RecordDecl*, 16> &AlreadyChecked) {
T = T.getCanonicalType();
// If this is a record, check it.
if (const RecordType *RT = dyn_cast<RecordType>(T))
return isSafeToConvert(RT->getDecl(), CGT, AlreadyChecked);
// If this is an array, check the elements, which are embedded inline.
if (const ArrayType *AT = dyn_cast<ArrayType>(T))
return isSafeToConvert(AT->getElementType(), CGT, AlreadyChecked);
// Otherwise, there is no concern about transforming this. We only care about
// things that are contained by-value in a structure that can have another
// structure as a member.
return true;
}
/// isSafeToConvert - Return true if it is safe to convert the specified record
/// decl to IR and lay it out, false if doing so would cause us to get into a
/// recursive compilation mess.
static bool isSafeToConvert(const RecordDecl *RD, CodeGenTypes &CGT) {
// If no structs are being laid out, we can certainly do this one.
if (CGT.noRecordsBeingLaidOut()) return true;
llvm::SmallPtrSet<const RecordDecl*, 16> AlreadyChecked;
return isSafeToConvert(RD, CGT, AlreadyChecked);
}
/// isFuncTypeArgumentConvertible - Return true if the specified type in a
/// function argument or result position can be converted to an IR type at this
/// point. This boils down to being whether it is complete, as well as whether
/// we've temporarily deferred expanding the type because we're in a recursive
/// context.
bool CodeGenTypes::isFuncTypeArgumentConvertible(QualType Ty) {
// If this isn't a tagged type, we can convert it!
const TagType *TT = Ty->getAs<TagType>();
if (TT == 0) return true;
// If it's a tagged type used by-value, but is just a forward decl, we can't
// convert it. Note that getDefinition()==0 is not the same as !isDefinition.
if (TT->getDecl()->getDefinition() == 0)
return false;
// If this is an enum, then it is always safe to convert.
const RecordType *RT = dyn_cast<RecordType>(TT);
if (RT == 0) return true;
// Otherwise, we have to be careful. If it is a struct that we're in the
// process of expanding, then we can't convert the function type. That's ok
// though because we must be in a pointer context under the struct, so we can
// just convert it to a dummy type.
//
// We decide this by checking whether ConvertRecordDeclType returns us an
// opaque type for a struct that we know is defined.
return isSafeToConvert(RT->getDecl(), *this);
}
/// Code to verify a given function type is complete, i.e. the return type
/// and all of the argument types are complete. Also check to see if we are in
/// a RS_StructPointer context, and if so whether any struct types have been
/// pended. If so, we don't want to ask the ABI lowering code to handle a type
/// that cannot be converted to an IR type.
bool CodeGenTypes::isFuncTypeConvertible(const FunctionType *FT) {
if (!isFuncTypeArgumentConvertible(FT->getResultType()))
return false;
if (const FunctionProtoType *FPT = dyn_cast<FunctionProtoType>(FT))
for (unsigned i = 0, e = FPT->getNumArgs(); i != e; i++)
if (!isFuncTypeArgumentConvertible(FPT->getArgType(i)))
return false;
return true;
}
/// UpdateCompletedType - When we find the full definition for a TagDecl,
/// replace the 'opaque' type we previously made for it if applicable.
void CodeGenTypes::UpdateCompletedType(const TagDecl *TD) {
// If this is an enum being completed, then we flush all non-struct types from
// the cache. This allows function types and other things that may be derived
// from the enum to be recomputed.
if (const EnumDecl *ED = dyn_cast<EnumDecl>(TD)) {
// Only flush the cache if we've actually already converted this type.
if (TypeCache.count(ED->getTypeForDecl())) {
// Okay, we formed some types based on this. We speculated that the enum
// would be lowered to i32, so we only need to flush the cache if this
// didn't happen.
if (!ConvertType(ED->getIntegerType())->isIntegerTy(32))
TypeCache.clear();
}
return;
}
// If we completed a RecordDecl that we previously used and converted to an
// anonymous type, then go ahead and complete it now.
const RecordDecl *RD = cast<RecordDecl>(TD);
if (RD->isDependentType()) return;
// Only complete it if we converted it already. If we haven't converted it
// yet, we'll just do it lazily.
if (RecordDeclTypes.count(Context.getTagDeclType(RD).getTypePtr()))
ConvertRecordDeclType(RD);
}
static llvm::Type *getTypeForFormat(llvm::LLVMContext &VMContext,
const llvm::fltSemantics &format) {
if (&format == &llvm::APFloat::IEEEsingle)
return llvm::Type::getFloatTy(VMContext);
if (&format == &llvm::APFloat::IEEEdouble)
return llvm::Type::getDoubleTy(VMContext);
if (&format == &llvm::APFloat::IEEEquad)
return llvm::Type::getFP128Ty(VMContext);
if (&format == &llvm::APFloat::PPCDoubleDouble)
return llvm::Type::getPPC_FP128Ty(VMContext);
if (&format == &llvm::APFloat::x87DoubleExtended)
return llvm::Type::getX86_FP80Ty(VMContext);
assert(0 && "Unknown float format!");
return 0;
}
/// ConvertType - Convert the specified type to its LLVM form.
llvm::Type *CodeGenTypes::ConvertType(QualType T) {
T = Context.getCanonicalType(T);
const Type *Ty = T.getTypePtr();
// RecordTypes are cached and processed specially.
if (const RecordType *RT = dyn_cast<RecordType>(Ty))
return ConvertRecordDeclType(RT->getDecl());
// See if type is already cached.
llvm::DenseMap<const Type *, llvm::Type *>::iterator TCI = TypeCache.find(Ty);
// If type is found in map then use it. Otherwise, convert type T.
if (TCI != TypeCache.end())
return TCI->second;
// If we don't have it in the cache, convert it now.
llvm::Type *ResultType = 0;
switch (Ty->getTypeClass()) {
case Type::Record: // Handled above.
#define TYPE(Class, Base)
#define ABSTRACT_TYPE(Class, Base)
#define NON_CANONICAL_TYPE(Class, Base) case Type::Class:
#define DEPENDENT_TYPE(Class, Base) case Type::Class:
#define NON_CANONICAL_UNLESS_DEPENDENT_TYPE(Class, Base) case Type::Class:
#include "clang/AST/TypeNodes.def"
llvm_unreachable("Non-canonical or dependent types aren't possible.");
break;
case Type::Builtin: {
switch (cast<BuiltinType>(Ty)->getKind()) {
case BuiltinType::Void:
case BuiltinType::ObjCId:
case BuiltinType::ObjCClass:
case BuiltinType::ObjCSel:
// LLVM void type can only be used as the result of a function call. Just
// map to the same as char.
ResultType = llvm::Type::getInt8Ty(getLLVMContext());
break;
case BuiltinType::Bool:
// Note that we always return bool as i1 for use as a scalar type.
ResultType = llvm::Type::getInt1Ty(getLLVMContext());
break;
case BuiltinType::Char_S:
case BuiltinType::Char_U:
case BuiltinType::SChar:
case BuiltinType::UChar:
case BuiltinType::Short:
case BuiltinType::UShort:
case BuiltinType::Int:
case BuiltinType::UInt:
case BuiltinType::Long:
case BuiltinType::ULong:
case BuiltinType::LongLong:
case BuiltinType::ULongLong:
case BuiltinType::WChar_S:
case BuiltinType::WChar_U:
case BuiltinType::Char16:
case BuiltinType::Char32:
ResultType = llvm::IntegerType::get(getLLVMContext(),
static_cast<unsigned>(Context.getTypeSize(T)));
break;
case BuiltinType::Float:
case BuiltinType::Double:
case BuiltinType::LongDouble:
ResultType = getTypeForFormat(getLLVMContext(),
Context.getFloatTypeSemantics(T));
break;
case BuiltinType::NullPtr:
// Model std::nullptr_t as i8*
ResultType = llvm::Type::getInt8PtrTy(getLLVMContext());
break;
case BuiltinType::UInt128:
case BuiltinType::Int128:
ResultType = llvm::IntegerType::get(getLLVMContext(), 128);
break;
case BuiltinType::Overload:
case BuiltinType::Dependent:
case BuiltinType::BoundMember:
case BuiltinType::UnknownAny:
llvm_unreachable("Unexpected placeholder builtin type!");
break;
}
break;
}
case Type::Complex: {
llvm::Type *EltTy = ConvertType(cast<ComplexType>(Ty)->getElementType());
ResultType = llvm::StructType::get(EltTy, EltTy, NULL);
break;
}
case Type::LValueReference:
case Type::RValueReference: {
const ReferenceType *RTy = cast<ReferenceType>(Ty);
QualType ETy = RTy->getPointeeType();
llvm::Type *PointeeType = ConvertTypeForMem(ETy);
unsigned AS = Context.getTargetAddressSpace(ETy);
ResultType = llvm::PointerType::get(PointeeType, AS);
break;
}
case Type::Pointer: {
const PointerType *PTy = cast<PointerType>(Ty);
QualType ETy = PTy->getPointeeType();
llvm::Type *PointeeType = ConvertTypeForMem(ETy);
if (PointeeType->isVoidTy())
PointeeType = llvm::Type::getInt8Ty(getLLVMContext());
unsigned AS = Context.getTargetAddressSpace(ETy);
ResultType = llvm::PointerType::get(PointeeType, AS);
break;
}
case Type::VariableArray: {
const VariableArrayType *A = cast<VariableArrayType>(Ty);
assert(A->getIndexTypeCVRQualifiers() == 0 &&
"FIXME: We only handle trivial array types so far!");
// VLAs resolve to the innermost element type; this matches
// the return of alloca, and there isn't any obviously better choice.
ResultType = ConvertTypeForMem(A->getElementType());
break;
}
case Type::IncompleteArray: {
const IncompleteArrayType *A = cast<IncompleteArrayType>(Ty);
assert(A->getIndexTypeCVRQualifiers() == 0 &&
"FIXME: We only handle trivial array types so far!");
// int X[] -> [0 x int], unless the element type is not sized. If it is
// unsized (e.g. an incomplete struct) just use [0 x i8].
ResultType = ConvertTypeForMem(A->getElementType());
if (!ResultType->isSized()) {
SkippedLayout = true;
ResultType = llvm::Type::getInt8Ty(getLLVMContext());
}
ResultType = llvm::ArrayType::get(ResultType, 0);
break;
}
case Type::ConstantArray: {
const ConstantArrayType *A = cast<ConstantArrayType>(Ty);
llvm::Type *EltTy = ConvertTypeForMem(A->getElementType());
// Lower arrays of undefined struct type to arrays of i8 just to have a
// concrete type.
if (!EltTy->isSized()) {
SkippedLayout = true;
EltTy = llvm::Type::getInt8Ty(getLLVMContext());
}
ResultType = llvm::ArrayType::get(EltTy, A->getSize().getZExtValue());
break;
}
case Type::ExtVector:
case Type::Vector: {
const VectorType *VT = cast<VectorType>(Ty);
ResultType = llvm::VectorType::get(ConvertType(VT->getElementType()),
VT->getNumElements());
break;
}
case Type::FunctionNoProto:
case Type::FunctionProto: {
const FunctionType *FT = cast<FunctionType>(Ty);
// First, check whether we can build the full function type. If the
// function type depends on an incomplete type (e.g. a struct or enum), we
// cannot lower the function type.
if (!isFuncTypeConvertible(FT)) {
// This function's type depends on an incomplete tag type.
// Return a placeholder type.
ResultType = llvm::StructType::get(getLLVMContext());
SkippedLayout = true;
break;
}
// While we're converting the argument types for a function, we don't want
// to recursively convert any pointed-to structs. Converting directly-used
// structs is ok though.
if (!RecordsBeingLaidOut.insert(Ty)) {
ResultType = llvm::StructType::get(getLLVMContext());
SkippedLayout = true;
break;
}
// The function type can be built; call the appropriate routines to
// build it.
const CGFunctionInfo *FI;
bool isVariadic;
if (const FunctionProtoType *FPT = dyn_cast<FunctionProtoType>(FT)) {
FI = &getFunctionInfo(
CanQual<FunctionProtoType>::CreateUnsafe(QualType(FPT, 0)));
isVariadic = FPT->isVariadic();
} else {
const FunctionNoProtoType *FNPT = cast<FunctionNoProtoType>(FT);
FI = &getFunctionInfo(
CanQual<FunctionNoProtoType>::CreateUnsafe(QualType(FNPT, 0)));
isVariadic = true;
}
// If there is something higher level prodding our CGFunctionInfo, then
// don't recurse into it again.
if (FunctionsBeingProcessed.count(FI)) {
ResultType = llvm::StructType::get(getLLVMContext());
SkippedLayout = true;
} else {
// Otherwise, we're good to go, go ahead and convert it.
ResultType = GetFunctionType(*FI, isVariadic);
}
RecordsBeingLaidOut.erase(Ty);
if (SkippedLayout)
TypeCache.clear();
if (RecordsBeingLaidOut.empty())
while (!DeferredRecords.empty())
ConvertRecordDeclType(DeferredRecords.pop_back_val());
break;
}
case Type::ObjCObject:
ResultType = ConvertType(cast<ObjCObjectType>(Ty)->getBaseType());
break;
case Type::ObjCInterface: {
// Objective-C interfaces are always opaque (outside of the
// runtime, which can do whatever it likes); we never refine
// these.
llvm::Type *&T = InterfaceTypes[cast<ObjCInterfaceType>(Ty)];
if (!T)
T = llvm::StructType::create(getLLVMContext());
ResultType = T;
break;
}
case Type::ObjCObjectPointer: {
// Protocol qualifications do not influence the LLVM type, we just return a
// pointer to the underlying interface type. We don't need to worry about
// recursive conversion.
llvm::Type *T =
ConvertTypeForMem(cast<ObjCObjectPointerType>(Ty)->getPointeeType());
ResultType = T->getPointerTo();
break;
}
case Type::Enum: {
const EnumDecl *ED = cast<EnumType>(Ty)->getDecl();
if (ED->isDefinition() || ED->isFixed())
return ConvertType(ED->getIntegerType());
// Return a placeholder 'i32' type. This can be changed later when the
// type is defined (see UpdateCompletedType), but is likely to be the
// "right" answer.
ResultType = llvm::Type::getInt32Ty(getLLVMContext());
break;
}
case Type::BlockPointer: {
const QualType FTy = cast<BlockPointerType>(Ty)->getPointeeType();
llvm::Type *PointeeType = ConvertTypeForMem(FTy);
unsigned AS = Context.getTargetAddressSpace(FTy);
ResultType = llvm::PointerType::get(PointeeType, AS);
break;
}
case Type::MemberPointer: {
ResultType =
getCXXABI().ConvertMemberPointerType(cast<MemberPointerType>(Ty));
break;
}
}
assert(ResultType && "Didn't convert a type?");
TypeCache[Ty] = ResultType;
return ResultType;
}
/// ConvertRecordDeclType - Lay out a tagged decl type like struct or union.
llvm::StructType *CodeGenTypes::ConvertRecordDeclType(const RecordDecl *RD) {
// TagDecl's are not necessarily unique, instead use the (clang)
// type connected to the decl.
const Type *Key = Context.getTagDeclType(RD).getTypePtr();
llvm::StructType *&Entry = RecordDeclTypes[Key];
// If we don't have a StructType at all yet, create the forward declaration.
if (Entry == 0) {
Entry = llvm::StructType::create(getLLVMContext());
addRecordTypeName(RD, Entry, "");
}
llvm::StructType *Ty = Entry;
// If this is still a forward declaration, or the LLVM type is already
// complete, there's nothing more to do.
RD = RD->getDefinition();
if (RD == 0 || !Ty->isOpaque())
return Ty;
// If converting this type would cause us to infinitely loop, don't do it!
if (!isSafeToConvert(RD, *this)) {
DeferredRecords.push_back(RD);
return Ty;
}
// Okay, this is a definition of a type. Compile the implementation now.
bool InsertResult = RecordsBeingLaidOut.insert(Key); (void)InsertResult;
assert(InsertResult && "Recursively compiling a struct?");
// Force conversion of non-virtual base classes recursively.
if (const CXXRecordDecl *CRD = dyn_cast<CXXRecordDecl>(RD)) {
for (CXXRecordDecl::base_class_const_iterator i = CRD->bases_begin(),
e = CRD->bases_end(); i != e; ++i) {
if (i->isVirtual()) continue;
ConvertRecordDeclType(i->getType()->getAs<RecordType>()->getDecl());
}
}
// Layout fields.
CGRecordLayout *Layout = ComputeRecordLayout(RD, Ty);
CGRecordLayouts[Key] = Layout;
// We're done laying out this struct.
bool EraseResult = RecordsBeingLaidOut.erase(Key); (void)EraseResult;
assert(EraseResult && "struct not in RecordsBeingLaidOut set?");
// If this struct blocked a FunctionType conversion, then recompute whatever
// was derived from that.
// FIXME: This is hugely overconservative.
if (SkippedLayout)
TypeCache.clear();
// If we're done converting the outer-most record, then convert any deferred
// structs as well.
if (RecordsBeingLaidOut.empty())
while (!DeferredRecords.empty())
ConvertRecordDeclType(DeferredRecords.pop_back_val());
return Ty;
}
/// getCGRecordLayout - Return record layout info for the given record decl.
const CGRecordLayout &
CodeGenTypes::getCGRecordLayout(const RecordDecl *RD) {
const Type *Key = Context.getTagDeclType(RD).getTypePtr();
const CGRecordLayout *Layout = CGRecordLayouts.lookup(Key);
if (!Layout) {
// Compute the type information.
ConvertRecordDeclType(RD);
// Now try again.
Layout = CGRecordLayouts.lookup(Key);
}
assert(Layout && "Unable to find record layout information for type");
return *Layout;
}
bool CodeGenTypes::isZeroInitializable(QualType T) {
// No need to check for member pointers when not compiling C++.
if (!Context.getLangOptions().CPlusPlus)
return true;
T = Context.getBaseElementType(T);
// Records are non-zero-initializable if they contain any
// non-zero-initializable subobjects.
if (const RecordType *RT = T->getAs<RecordType>()) {
const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
return isZeroInitializable(RD);
}
// We have to ask the ABI about member pointers.
if (const MemberPointerType *MPT = T->getAs<MemberPointerType>())
return getCXXABI().isZeroInitializable(MPT);
// Everything else is okay.
return true;
}
bool CodeGenTypes::isZeroInitializable(const CXXRecordDecl *RD) {
return getCGRecordLayout(RD).isZeroInitializable();
}
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