path: root/lib/CodeGen/CodeGenTypes.cpp

//===--- 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: {
    const llvm::Type *EltTy = 
      ConvertType(cast<ComplexType>(Ty).getElementType());
    return llvm::StructType::get(EltTy, EltTy, NULL);
  }
  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() == </