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llvm-project/clang/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 "clang/Basic/TargetInfo.h"
#include "clang/AST/AST.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Module.h"
#include "llvm/Target/TargetData.h"
using namespace clang;
using namespace CodeGen;
namespace {
/// RecordOrganizer - This helper class, used by CGRecordLayout, layouts
/// structs and unions. It manages transient information used during layout.
/// FIXME : Handle field aligments. Handle packed structs.
class RecordOrganizer {
public:
explicit RecordOrganizer(CodeGenTypes &Types) :
CGT(Types), STy(NULL), llvmFieldNo(0), Cursor(0),
llvmSize(0) {}
/// addField - Add new field.
void addField(const FieldDecl *FD);
/// addLLVMField - Add llvm struct field that corresponds to llvm type Ty.
/// Increment field count.
void addLLVMField(const llvm::Type *Ty, bool isPaddingField = false);
/// addPaddingFields - Current cursor is not suitable place to add next
/// field. Add required padding fields.
void addPaddingFields(unsigned WaterMark);
/// layoutStructFields - Do the actual work and lay out all fields. Create
/// corresponding llvm struct type. This should be invoked only after
/// all fields are added.
void layoutStructFields(const ASTRecordLayout &RL);
/// layoutUnionFields - Do the actual work and lay out all fields. Create
/// corresponding llvm struct type. This should be invoked only after
/// all fields are added.
void layoutUnionFields();
/// getLLVMType - Return associated llvm struct type. This may be NULL
/// if fields are not laid out.
llvm::Type *getLLVMType() const {
return STy;
}
/// placeBitField - Find a place for FD, which is a bit-field.
void placeBitField(const FieldDecl *FD);
llvm::SmallSet<unsigned, 8> &getPaddingFields() {
return PaddingFields;
}
private:
CodeGenTypes &CGT;
llvm::Type *STy;
unsigned llvmFieldNo;
uint64_t Cursor;
uint64_t llvmSize;
llvm::SmallVector<const FieldDecl *, 8> FieldDecls;
std::vector<const llvm::Type*> LLVMFields;
llvm::SmallSet<unsigned, 8> PaddingFields;
};
}
CodeGenTypes::CodeGenTypes(ASTContext &Ctx, llvm::Module& M,
const llvm::TargetData &TD)
: Context(Ctx), Target(Ctx.Target), TheModule(M), TheTargetData(TD) {
}
CodeGenTypes::~CodeGenTypes() {
for(llvm::DenseMap<const TagDecl *, CGRecordLayout *>::iterator
I = CGRecordLayouts.begin(), E = CGRecordLayouts.end();
I != E; ++I)
delete I->second;
CGRecordLayouts.clear();
}
/// ConvertType - Convert the specified type to its LLVM form.
const llvm::Type *CodeGenTypes::ConvertType(QualType T) {
// See if type is already cached.
llvm::DenseMap<Type *, llvm::PATypeHolder>::iterator
I = TypeCache.find(T.getCanonicalType().getTypePtr());
// If type is found in map and this is not a definition for a opaque
// place holder type then use it. Otherwise, convert type T.
if (I != TypeCache.end())
return I->second.get();
const llvm::Type *ResultType = ConvertNewType(T);
TypeCache.insert(std::make_pair(T.getCanonicalType().getTypePtr(),
llvm::PATypeHolder(ResultType)));
return ResultType;
}
/// 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.
const llvm::Type *CodeGenTypes::ConvertTypeForMem(QualType T) {
const llvm::Type *R = ConvertType(T);
// If this is a non-bool type, don't map it.
if (R != llvm::Type::Int1Ty)
return R;
// Otherwise, return an integer of the target-specified size.
return llvm::IntegerType::get((unsigned)Context.getTypeSize(T));
}
/// 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) {
llvm::DenseMap<const TagDecl*, llvm::PATypeHolder>::iterator TDTI =
TagDeclTypes.find(TD);
if (TDTI == TagDeclTypes.end()) return;
// Remember the opaque LLVM type for this tagdecl.
llvm::PATypeHolder OpaqueHolder = TDTI->second;
assert(isa<llvm::OpaqueType>(OpaqueHolder.get()) &&
"Updating compilation of an already non-opaque type?");
// Remove it from TagDeclTypes so that it will be regenerated.
TagDeclTypes.erase(TDTI);
// Generate the new type.
const llvm::Type *NT = ConvertTagDeclType(TD);
// Refine the old opaque type to its new definition.
cast<llvm::OpaqueType>(OpaqueHolder.get())->refineAbstractTypeTo(NT);
}
const llvm::Type *CodeGenTypes::ConvertNewType(QualType T) {
const clang::Type &Ty = *T.getCanonicalType();
switch (Ty.getTypeClass()) {
case Type::TypeName: // typedef isn't canonical.
case Type::TypeOfExp: // typeof isn't canonical.
case Type::TypeOfTyp: // typeof isn't canonical.
assert(0 && "Non-canonical type, shouldn't happen");
case Type::Builtin: {
switch (cast<BuiltinType>(Ty).getKind()) {
case BuiltinType::Void:
// LLVM void type can only be used as the result of a function call. Just
// map to the same as char.
return llvm::IntegerType::get(8);
case BuiltinType::Bool:
// Note that we always return bool as i1 for use as a scalar type.
return llvm::Type::Int1Ty;
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:
return llvm::IntegerType::get(
static_cast<unsigned>(Context.getTypeSize(T)));
case BuiltinType::Float: return llvm::Type::FloatTy;
case BuiltinType::Double: return llvm::Type::DoubleTy;
case BuiltinType::LongDouble:
// FIXME: mapping long double onto double.
return llvm::Type::DoubleTy;
}
break;
}
case Type::Complex: {
std::vector<const llvm::Type*> Elts;
Elts.push_back(ConvertType(cast<ComplexType>(Ty).getElementType()));
Elts.push_back(Elts[0]);
return llvm::StructType::get(Elts);
}
case Type::Pointer: {
const PointerType &P = cast<PointerType>(Ty);
QualType ETy = P.getPointeeType();
return llvm::PointerType::get(ConvertType(ETy), ETy.getAddressSpace());
}
case Type::Reference: {
const ReferenceType &R = cast<ReferenceType>(Ty);
return llvm::PointerType::getUnqual(ConvertType(R.getReferenceeType()));
}
case Type::VariableArray: {
const VariableArrayType &A = cast<VariableArrayType>(Ty);
assert(A.getIndexTypeQualifier() == 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.
return ConvertType(A.getElementType());
}
case Type::IncompleteArray: {
const IncompleteArrayType &A = cast<IncompleteArrayType>(Ty);
assert(A.getIndexTypeQualifier() == 0 &&
"FIXME: We only handle trivial array types so far!");
// int X[] -> [0 x int]
return llvm::ArrayType::get(ConvertType(A.getElementType()), 0);
}
case Type::ConstantArray: {
const ConstantArrayType &A = cast<ConstantArrayType>(Ty);
const llvm::Type *EltTy = ConvertType(A.getElementType());
return llvm::ArrayType::get(EltTy, A.getSize().getZExtValue());
}
case Type::OCUVector:
case Type::Vector: {
const VectorType &VT = cast<VectorType>(Ty);
return llvm::VectorType::get(ConvertType(VT.getElementType()),
VT.getNumElements());
}
case Type::FunctionNoProto:
case Type::FunctionProto: {
const FunctionType &FP = cast<FunctionType>(Ty);
const llvm::Type *ResultType;
if (FP.getResultType()->isVoidType())
ResultType = llvm::Type::VoidTy; // Result of function uses llvm void.
else
ResultType = ConvertType(FP.getResultType());
// FIXME: Convert argument types.
bool isVarArg;
std::vector<const llvm::Type*> ArgTys;
// Struct return passes the struct byref.
if (!ResultType->isFirstClassType() && ResultType != llvm::Type::VoidTy) {
ArgTys.push_back(llvm::PointerType::get(ResultType,
FP.getResultType().getAddressSpace()));
ResultType = llvm::Type::VoidTy;
}
if (const FunctionTypeProto *FTP = dyn_cast<FunctionTypeProto>(&FP)) {
DecodeArgumentTypes(*FTP, ArgTys);
isVarArg = FTP->isVariadic();
} else {
isVarArg = true;
}
return llvm::FunctionType::get(ResultType, ArgTys, isVarArg);
}
case Type::ASQual:
return ConvertType(QualType(cast<ASQualType>(Ty).getBaseType(), 0));
case Type::ObjCInterface:
assert(0 && "FIXME: add missing functionality here");
break;
case Type::ObjCQualifiedInterface:
assert(0 && "FIXME: add missing functionality here");
break;
case Type::ObjCQualifiedId:
assert(0 && "FIXME: add missing functionality here");
break;
case Type::Tagged: {
const TagDecl *TD = cast<TagType>(Ty).getDecl();
const llvm::Type *Res = ConvertTagDeclType(TD);
std::string TypeName(TD->getKindName());
TypeName += '.';
// Name the codegen type after the typedef name
// if there is no tag type name available
if (TD->getIdentifier())
TypeName += TD->getName();
else if (const TypedefType *TdT = dyn_cast<TypedefType>(T))
TypeName += TdT->getDecl()->getName();
else
TypeName += "anon";
TheModule.addTypeName(TypeName, Res);
return Res;
}
}
// FIXME: implement.
return llvm::OpaqueType::get();
}
void CodeGenTypes::DecodeArgumentTypes(const FunctionTypeProto &FTP,
std::vector<const llvm::Type*> &ArgTys) {
for (unsigned i = 0, e = FTP.getNumArgs(); i != e; ++i) {
const llvm::Type *Ty = ConvertType(FTP.getArgType(i));
if (Ty->isFirstClassType())
ArgTys.push_back(Ty);
else
// byval arguments are always on the stack, which is addr space #0.
ArgTys.push_back(llvm::PointerType::getUnqual(Ty));
}
}
/// ConvertTagDeclType - Lay out a tagged decl type like struct or union or
/// enum.
const llvm::Type *CodeGenTypes::ConvertTagDeclType(const TagDecl *TD) {
llvm::DenseMap<const TagDecl*, llvm::PATypeHolder>::iterator TDTI =
TagDeclTypes.find(TD);
// If we've already compiled this tag type, use the previous definition.
if (TDTI != TagDeclTypes.end())
return TDTI->second;
// If this is still a forward definition, just define an opaque type to use
// for this tagged decl.
if (!TD->isDefinition()) {
llvm::Type *ResultType = llvm::OpaqueType::get();
TagDeclTypes.insert(std::make_pair(TD, ResultType));
return ResultType;
}
// Okay, this is a definition of a type. Compile the implementation now.
if (TD->getKind() == Decl::Enum) {
// Don't bother storing enums in TagDeclTypes.
return ConvertType(cast<EnumDecl>(TD)->getIntegerType());
}
// This decl could well be recursive. In this case, insert an opaque
// definition of this type, which the recursive uses will get. We will then
// refine this opaque version later.
// Create new OpaqueType now for later use in case this is a recursive
// type. This will later be refined to the actual type.
llvm::PATypeHolder ResultHolder = llvm::OpaqueType::get();
TagDeclTypes.insert(std::make_pair(TD, ResultHolder));
const llvm::Type *ResultType;
const RecordDecl *RD = cast<const RecordDecl>(TD);
if (TD->getKind() == Decl::Struct || TD->getKind() == Decl::Class) {
// Layout fields.
RecordOrganizer RO(*this);
for (unsigned i = 0, e = RD->getNumMembers(); i != e; ++i)
RO.addField(RD->getMember(i));
RO.layoutStructFields(Context.getASTRecordLayout(RD));
// Get llvm::StructType.
CGRecordLayouts[TD] = new CGRecordLayout(RO.getLLVMType(),
RO.getPaddingFields());
ResultType = RO.getLLVMType();
} else if (TD->getKind() == Decl::Union) {
// Just use the largest element of the union, breaking ties with the
// highest aligned member.
if (RD->getNumMembers() != 0) {
RecordOrganizer RO(*this);
for (unsigned i = 0, e = RD->getNumMembers(); i != e; ++i)
RO.addField(RD->getMember(i));
RO.layoutUnionFields();
// Get llvm::StructType.
CGRecordLayouts[TD] = new CGRecordLayout(RO.getLLVMType(),
RO.getPaddingFields());
ResultType = RO.getLLVMType();
} else {
ResultType = llvm::StructType::get(std::vector<const llvm::Type*>());
}
} else {
assert(0 && "FIXME: Unknown tag decl kind!");
}
// Refine our Opaque type to ResultType. This can invalidate ResultType, so
// make sure to read the result out of the holder.
cast<llvm::OpaqueType>(ResultHolder.get())
->refineAbstractTypeTo(ResultType);
return ResultHolder.get();
}
/// getLLVMFieldNo - Return llvm::StructType element number
/// that corresponds to the field FD.
unsigned CodeGenTypes::getLLVMFieldNo(const FieldDecl *FD) {
llvm::DenseMap<const FieldDecl *, unsigned>::iterator
I = FieldInfo.find(FD);
assert (I != FieldInfo.end() && "Unable to find field info");
return I->second;
}
/// addFieldInfo - Assign field number to field FD.
void CodeGenTypes::addFieldInfo(const FieldDecl *FD, unsigned No) {
FieldInfo[FD] = No;
}
/// getBitFieldInfo - Return the BitFieldInfo that corresponds to the field FD.
CodeGenTypes::BitFieldInfo CodeGenTypes::getBitFieldInfo(const FieldDecl *FD) {
llvm::DenseMap<const FieldDecl *, BitFieldInfo>::iterator
I = BitFields.find(FD);
assert (I != BitFields.end() && "Unable to find bitfield info");
return I->second;
}
/// addBitFieldInfo - Assign a start bit and a size to field FD.
void CodeGenTypes::addBitFieldInfo(const FieldDecl *FD, unsigned Begin,
unsigned Size) {
BitFields.insert(std::make_pair(FD, BitFieldInfo(Begin, Size)));
}
/// getCGRecordLayout - Return record layout info for the given llvm::Type.
const CGRecordLayout *
CodeGenTypes::getCGRecordLayout(const TagDecl *TD) const {
llvm::DenseMap<const TagDecl*, CGRecordLayout *>::iterator I
= CGRecordLayouts.find(TD);
assert (I != CGRecordLayouts.end()
&& "Unable to find record layout information for type");
return I->second;
}
/// addField - Add new field.
void RecordOrganizer::addField(const FieldDecl *FD) {
assert (!STy && "Record fields are already laid out");
FieldDecls.push_back(FD);
}
/// layoutStructFields - Do the actual work and lay out all fields. Create
/// corresponding llvm struct type. This should be invoked only after
/// all fields are added.
/// FIXME : At the moment assume
/// - one to one mapping between AST FieldDecls and
/// llvm::StructType elements.
/// - Ignore bit fields
/// - Ignore field aligments
/// - Ignore packed structs
void RecordOrganizer::layoutStructFields(const ASTRecordLayout &RL) {
// FIXME : Use SmallVector
llvmSize = 0;
llvmFieldNo = 0;
Cursor = 0;
LLVMFields.clear();
for (llvm::SmallVector<const FieldDecl *, 8>::iterator I = FieldDecls.begin(),
E = FieldDecls.end(); I != E; ++I) {
const FieldDecl *FD = *I;
if (FD->isBitField())
placeBitField(FD);
else {
const llvm::Type *Ty = CGT.ConvertType(FD->getType());
addLLVMField(Ty);
CGT.addFieldInfo(FD, llvmFieldNo - 1);
Cursor = llvmSize;
}
}
unsigned StructAlign = RL.getAlignment();
if (llvmSize % StructAlign) {
unsigned StructPadding = StructAlign - (llvmSize % StructAlign);
addPaddingFields(llvmSize + StructPadding);
}
STy = llvm::StructType::get(LLVMFields);
}
/// addPaddingFields - Current cursor is not suitable place to add next field.
/// Add required padding fields.
void RecordOrganizer::addPaddingFields(unsigned WaterMark) {
assert(WaterMark >= llvmSize && "Invalid padding Field");
unsigned RequiredBits = WaterMark - llvmSize;
unsigned RequiredBytes = (RequiredBits + 7) / 8;
for (unsigned i = 0; i != RequiredBytes; ++i)
addLLVMField(llvm::Type::Int8Ty, true);
}
/// addLLVMField - Add llvm struct field that corresponds to llvm type Ty.
/// Increment field count.
void RecordOrganizer::addLLVMField(const llvm::Type *Ty, bool isPaddingField) {
unsigned AlignmentInBits = CGT.getTargetData().getABITypeAlignment(Ty) * 8;
if (llvmSize % AlignmentInBits) {
// At the moment, insert padding fields even if target specific llvm
// type alignment enforces implict padding fields for FD. Later on,
// optimize llvm fields by removing implicit padding fields and
// combining consequetive padding fields.
unsigned Padding = AlignmentInBits - (llvmSize % AlignmentInBits);
addPaddingFields(llvmSize + Padding);
}
unsigned TySize = CGT.getTargetData().getABITypeSizeInBits(Ty);
llvmSize += TySize;
if (isPaddingField)
PaddingFields.insert(llvmFieldNo);
LLVMFields.push_back(Ty);
++llvmFieldNo;
}
/// layoutUnionFields - Do the actual work and lay out all fields. Create
/// corresponding llvm struct type. This should be invoked only after
/// all fields are added.
void RecordOrganizer::layoutUnionFields() {
unsigned PrimaryEltNo = 0;
std::pair<uint64_t, unsigned> PrimaryElt =
CGT.getContext().getTypeInfo(FieldDecls[0]->getType());
CGT.addFieldInfo(FieldDecls[0], 0);
unsigned Size = FieldDecls.size();
for(unsigned i = 1; i != Size; ++i) {
const FieldDecl *FD = FieldDecls[i];
assert (!FD->isBitField() && "Bit fields are not yet supported");
std::pair<uint64_t, unsigned> EltInfo =
CGT.getContext().getTypeInfo(FD->getType());
// Use largest element, breaking ties with the hightest aligned member.
if (EltInfo.first > PrimaryElt.first ||
(EltInfo.first == PrimaryElt.first &&
EltInfo.second > PrimaryElt.second)) {
PrimaryElt = EltInfo;
PrimaryEltNo = i;
}
// In union, each field gets first slot.
CGT.addFieldInfo(FD, 0);
}
std::vector<const llvm::Type*> Fields;
const llvm::Type *Ty = CGT.ConvertType(FieldDecls[PrimaryEltNo]->getType());
Fields.push_back(Ty);
STy = llvm::StructType::get(Fields);
}
/// placeBitField - Find a place for FD, which is a bit-field.
/// This function searches for the last aligned field. If the bit-field fits in
/// it, it is reused. Otherwise, the bit-field is placed in a new field.
void RecordOrganizer::placeBitField(const FieldDecl *FD) {
assert (FD->isBitField() && "FD is not a bit-field");
Expr *BitWidth = FD->getBitWidth();
llvm::APSInt FieldSize(32);
bool isBitField =
BitWidth->isIntegerConstantExpr(FieldSize, CGT.getContext());
assert (isBitField && "Invalid BitField size expression");
uint64_t BitFieldSize = FieldSize.getZExtValue();
const llvm::Type *Ty = CGT.ConvertType(FD->getType());
uint64_t TySize = CGT.getTargetData().getABITypeSizeInBits(Ty);
unsigned Idx = Cursor / TySize;
unsigned BitsLeft = TySize - (Cursor % TySize);
if (BitsLeft >= BitFieldSize) {
// The bitfield fits in the last aligned field.
// This is : struct { char a; int CurrentField:10;};
// where 'CurrentField' shares first field with 'a'.
CGT.addFieldInfo(FD, Idx);
CGT.addBitFieldInfo(FD, TySize - BitsLeft, BitFieldSize);
Cursor += BitFieldSize;
} else {
// Place the bitfield in a new LLVM field.
// This is : struct { char a; short CurrentField:10;};
// where 'CurrentField' needs a new llvm field.
CGT.addFieldInfo(FD, Idx + 1);
CGT.addBitFieldInfo(FD, 0, BitFieldSize);
Cursor = (Idx + 1) * TySize + BitFieldSize;
}
if (Cursor > llvmSize)
addPaddingFields(Cursor);
}
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