ASTContext.cpp

//===--- ASTContext.cpp - Context to hold long-lived AST nodes ------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
//  This file implements the ASTContext interface.
//
//===----------------------------------------------------------------------===//

#include "clang/AST/ASTContext.h"
#include "clang/AST/Decl.h"
#include "clang/AST/DeclObjC.h"
#include "clang/Basic/TargetInfo.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/Bitcode/Serialize.h"
#include "llvm/Bitcode/Deserialize.h"

using namespace clang;

enum FloatingRank {
  FloatRank, DoubleRank, LongDoubleRank
};

ASTContext::~ASTContext() {
  // Deallocate all the types.
  while (!Types.empty()) {
    if (FunctionTypeProto *FT = dyn_cast<FunctionTypeProto>(Types.back())) {
      // Destroy the object, but don't call delete.  These are malloc'd.
      FT->~FunctionTypeProto();
      free(FT);
    } else {
      delete Types.back();
    }
    Types.pop_back();
  }
}

void ASTContext::PrintStats() const {
  fprintf(stderr, "*** AST Context Stats:\n");
  fprintf(stderr, "  %d types total.\n", (int)Types.size());
  unsigned NumBuiltin = 0, NumPointer = 0, NumArray = 0, NumFunctionP = 0;
  unsigned NumVector = 0, NumComplex = 0;
  unsigned NumFunctionNP = 0, NumTypeName = 0, NumTagged = 0, NumReference = 0;
  
  unsigned NumTagStruct = 0, NumTagUnion = 0, NumTagEnum = 0, NumTagClass = 0;
  unsigned NumObjCInterfaces = 0, NumObjCQualifiedInterfaces = 0;
  unsigned NumObjCQualifiedIds = 0;
  
  for (unsigned i = 0, e = Types.size(); i != e; ++i) {
    Type *T = Types[i];
    if (isa<BuiltinType>(T))
      ++NumBuiltin;
    else if (isa<PointerType>(T))
      ++NumPointer;
    else if (isa<ReferenceType>(T))
      ++NumReference;
    else if (isa<ComplexType>(T))
      ++NumComplex;
    else if (isa<ArrayType>(T))
      ++NumArray;
    else if (isa<VectorType>(T))
      ++NumVector;
    else if (isa<FunctionTypeNoProto>(T))
      ++NumFunctionNP;
    else if (isa<FunctionTypeProto>(T))
      ++NumFunctionP;
    else if (isa<TypedefType>(T))
      ++NumTypeName;
    else if (TagType *TT = dyn_cast<TagType>(T)) {
      ++NumTagged;
      switch (TT->getDecl()->getKind()) {
      default: assert(0 && "Unknown tagged type!");
      case Decl::Struct: ++NumTagStruct; break;
      case Decl::Union:  ++NumTagUnion; break;
      case Decl::Class:  ++NumTagClass; break; 
      case Decl::Enum:   ++NumTagEnum; break;
      }
    } else if (isa<ObjCInterfaceType>(T))
      ++NumObjCInterfaces;
    else if (isa<ObjCQualifiedInterfaceType>(T))
      ++NumObjCQualifiedInterfaces;
    else if (isa<ObjCQualifiedIdType>(T))
      ++NumObjCQualifiedIds;
    else {
      QualType(T, 0).dump();
      assert(0 && "Unknown type!");
    }
  }

  fprintf(stderr, "    %d builtin types\n", NumBuiltin);
  fprintf(stderr, "    %d pointer types\n", NumPointer);
  fprintf(stderr, "    %d reference types\n", NumReference);
  fprintf(stderr, "    %d complex types\n", NumComplex);
  fprintf(stderr, "    %d array types\n", NumArray);
  fprintf(stderr, "    %d vector types\n", NumVector);
  fprintf(stderr, "    %d function types with proto\n", NumFunctionP);
  fprintf(stderr, "    %d function types with no proto\n", NumFunctionNP);
  fprintf(stderr, "    %d typename (typedef) types\n", NumTypeName);
  fprintf(stderr, "    %d tagged types\n", NumTagged);
  fprintf(stderr, "      %d struct types\n", NumTagStruct);
  fprintf(stderr, "      %d union types\n", NumTagUnion);
  fprintf(stderr, "      %d class types\n", NumTagClass);
  fprintf(stderr, "      %d enum types\n", NumTagEnum);
  fprintf(stderr, "    %d interface types\n", NumObjCInterfaces);
  fprintf(stderr, "    %d protocol qualified interface types\n",
          NumObjCQualifiedInterfaces);
  fprintf(stderr, "    %d protocol qualified id types\n",
          NumObjCQualifiedIds);
  fprintf(stderr, "Total bytes = %d\n", int(NumBuiltin*sizeof(BuiltinType)+
    NumPointer*sizeof(PointerType)+NumArray*sizeof(ArrayType)+
    NumComplex*sizeof(ComplexType)+NumVector*sizeof(VectorType)+
    NumFunctionP*sizeof(FunctionTypeProto)+
    NumFunctionNP*sizeof(FunctionTypeNoProto)+
    NumTypeName*sizeof(TypedefType)+NumTagged*sizeof(TagType)));
}


void ASTContext::InitBuiltinType(QualType &R, BuiltinType::Kind K) {
  Types.push_back((R = QualType(new BuiltinType(K),0)).getTypePtr());
}

void ASTContext::InitBuiltinTypes() {
  assert(VoidTy.isNull() && "Context reinitialized?");
  
  // C99 6.2.5p19.
  InitBuiltinType(VoidTy,              BuiltinType::Void);
  
  // C99 6.2.5p2.
  InitBuiltinType(BoolTy,              BuiltinType::Bool);
  // C99 6.2.5p3.
  if (Target.isCharSigned(FullSourceLoc()))
    InitBuiltinType(CharTy,            BuiltinType::Char_S);
  else
    InitBuiltinType(CharTy,            BuiltinType::Char_U);
  // C99 6.2.5p4.
  InitBuiltinType(SignedCharTy,        BuiltinType::SChar);
  InitBuiltinType(ShortTy,             BuiltinType::Short);
  InitBuiltinType(IntTy,               BuiltinType::Int);
  InitBuiltinType(LongTy,              BuiltinType::Long);
  InitBuiltinType(LongLongTy,          BuiltinType::LongLong);
  
  // C99 6.2.5p6.
  InitBuiltinType(UnsignedCharTy,      BuiltinType::UChar);
  InitBuiltinType(UnsignedShortTy,     BuiltinType::UShort);
  InitBuiltinType(UnsignedIntTy,       BuiltinType::UInt);
  InitBuiltinType(UnsignedLongTy,      BuiltinType::ULong);
  InitBuiltinType(UnsignedLongLongTy,  BuiltinType::ULongLong);
  
  // C99 6.2.5p10.
  InitBuiltinType(FloatTy,             BuiltinType::Float);
  InitBuiltinType(DoubleTy,            BuiltinType::Double);
  InitBuiltinType(LongDoubleTy,        BuiltinType::LongDouble);
  
  // C99 6.2.5p11.
  FloatComplexTy      = getComplexType(FloatTy);
  DoubleComplexTy     = getComplexType(DoubleTy);
  LongDoubleComplexTy = getComplexType(LongDoubleTy);
  
  BuiltinVaListType = QualType();
  ObjCIdType = QualType();
  IdStructType = 0;
  ObjCClassType = QualType();
  ClassStructType = 0;
  
  ObjCConstantStringType = QualType();
  
  // void * type
  VoidPtrTy = getPointerType(VoidTy);
}

//===----------------------------------------------------------------------===//
//                         Type Sizing and Analysis
//===----------------------------------------------------------------------===//

/// getTypeSize - Return the size of the specified type, in bits.  This method
/// does not work on incomplete types.
std::pair<uint64_t, unsigned>
ASTContext::getTypeInfo(QualType T, SourceLocation L) {
  T = T.getCanonicalType();
  uint64_t Size;
  unsigned Align;
  switch (T->getTypeClass()) {
  case Type::TypeName: assert(0 && "Not a canonical type!");
  case Type::FunctionNoProto:
  case Type::FunctionProto:
  default:
    assert(0 && "Incomplete types have no size!");
  case Type::VariableArray:
    assert(0 && "VLAs not implemented yet!");
  case Type::ConstantArray: {
    ConstantArrayType *CAT = cast<ConstantArrayType>(T);
    
    std::pair<uint64_t, unsigned> EltInfo = 
      getTypeInfo(CAT->getElementType(), L);
    Size = EltInfo.first*CAT->getSize().getZExtValue();
    Align = EltInfo.second;
    break;
  }
  case Type::OCUVector:
  case Type::Vector: {
    std::pair<uint64_t, unsigned> EltInfo = 
      getTypeInfo(cast<VectorType>(T)->getElementType(), L);
    Size = EltInfo.first*cast<VectorType>(T)->getNumElements();
    // FIXME: Vector alignment is not the alignment of its elements.
    Align = EltInfo.second;
    break;
  }

  case Type::Builtin: {
    // FIXME: need to use TargetInfo to derive the target specific sizes. This
    // implementation will suffice for play with vector support.
    const llvm::fltSemantics *F;
    switch (cast<BuiltinType>(T)->getKind()) {
    default: assert(0 && "Unknown builtin type!");
    case BuiltinType::Void:
      assert(0 && "Incomplete types have no size!");
    case BuiltinType::Bool:
      Target.getBoolInfo(Size, Align, getFullLoc(L));
      break;
    case BuiltinType::Char_S:
    case BuiltinType::Char_U:
    case BuiltinType::UChar:
    case BuiltinType::SChar:
      Target.getCharInfo(Size, Align, getFullLoc(L));
      break;
    case BuiltinType::UShort:
    case BuiltinType::Short:
      Target.getShortInfo(Size, Align, getFullLoc(L));
      break;
    case BuiltinType::UInt:
    case BuiltinType::Int:
      Target.getIntInfo(Size, Align, getFullLoc(L));
      break;
    case BuiltinType::ULong:
    case BuiltinType::Long:
      Target.getLongInfo(Size, Align, getFullLoc(L));
      break;
    case BuiltinType::ULongLong:
    case BuiltinType::LongLong:
      Target.getLongLongInfo(Size, Align, getFullLoc(L));
      break;
    case BuiltinType::Float:
      Target.getFloatInfo(Size, Align, F, getFullLoc(L));
      break;
    case BuiltinType::Double:
      Target.getDoubleInfo(Size, Align, F, getFullLoc(L));
      break;
    case BuiltinType::LongDouble:
      Target.getLongDoubleInfo(Size, Align, F, getFullLoc(L));
      break;
    }
    break;
  }
  case Type::ASQual:
    return getTypeInfo(QualType(cast<ASQualType>(T)->getBaseType(), 0), L);
  case Type::ObjCQualifiedId:
    Target.getPointerInfo(Size, Align, getFullLoc(L));
    break;
  case Type::Pointer:
    Target.getPointerInfo(Size, Align, getFullLoc(L));
    break;
  case Type::Reference:
    // "When applied to a reference or a reference type, the result is the size
    // of the referenced type." C++98 5.3.3p2: expr.sizeof.
    // FIXME: This is wrong for struct layout: a reference in a struct has
    // pointer size.
    return getTypeInfo(cast<ReferenceType>(T)->getReferenceeType(), L);
    
  case Type::Complex: {
    // Complex types have the same alignment as their elements, but twice the
    // size.
    std::pair<uint64_t, unsigned> EltInfo = 
      getTypeInfo(cast<ComplexType>(T)->getElementType(), L);
    Size = EltInfo.first*2;
    Align = EltInfo.second;
    break;
  }
  case Type::Tagged:
    TagType *TT = cast<TagType>(T);
    if (RecordType *RT = dyn_cast<RecordType>(TT)) {
      const ASTRecordLayout &Layout = getASTRecordLayout(RT->getDecl(), L);
      Size = Layout.getSize();
      Align = Layout.getAlignment();
    } else if (EnumDecl *ED = dyn_cast<EnumDecl>(TT->getDecl())) {
      return getTypeInfo(ED->getIntegerType(), L);
    } else {
      assert(0 && "Unimplemented type sizes!");
    }
    break;
  }
  
  assert(Align && (Align & (Align-1)) == 0 && "Alignment must be power of 2");
  return std::make_pair(Size, Align);
}

/// getASTRecordLayout - Get or compute information about the layout of the
/// specified record (struct/union/class), which indicates its size and field
/// position information.
const ASTRecordLayout &ASTContext::getASTRecordLayout(const RecordDecl *D,
                                                      SourceLocation L) {
  assert(D->isDefinition() && "Cannot get layout of forward declarations!");
  
  // Look up this layout, if already laid out, return what we have.
  const ASTRecordLayout *&Entry = ASTRecordLayouts[D];
  if (Entry) return *Entry;
  
  // Allocate and assign into ASTRecordLayouts here.  The "Entry" reference can
  // be invalidated (dangle) if the ASTRecordLayouts hashtable is inserted into.
  ASTRecordLayout *NewEntry = new ASTRecordLayout();
  Entry = NewEntry;
  
  uint64_t *FieldOffsets = new uint64_t[D->getNumMembers()];
  uint64_t RecordSize = 0;
  unsigned RecordAlign = 8;  // Default alignment = 1 byte = 8 bits.

  if (D->getKind() != Decl::Union) {
    if (const AlignedAttr *AA = D->getAttr<AlignedAttr>())
      RecordAlign = std::max(RecordAlign, AA->getAlignment());
        
    bool StructIsPacked = D->getAttr<PackedAttr>();
    
    // Layout each field, for now, just sequentially, respecting alignment.  In
    // the future, this will need to be tweakable by targets.
    for (unsigned i = 0, e = D->getNumMembers(); i != e; ++i) {
      const FieldDecl *FD = D->getMember(i);
      bool FieldIsPacked = StructIsPacked || FD->getAttr<PackedAttr>();
      uint64_t FieldSize;
      unsigned FieldAlign;
      
      if (const Expr *BitWidthExpr = FD->getBitWidth()) {
        llvm::APSInt I(32);
        bool BitWidthIsICE = 
          BitWidthExpr->isIntegerConstantExpr(I, *this);
        assert (BitWidthIsICE  && "Invalid BitField size expression");
        FieldSize = I.getZExtValue();

        std::pair<uint64_t, unsigned> TypeInfo = getTypeInfo(FD->getType(), L);
        uint64_t TypeSize = TypeInfo.first;
        
        if (const AlignedAttr *AA = FD->getAttr<AlignedAttr>())
          FieldAlign = AA->getAlignment();
        else if (FieldIsPacked)
          FieldAlign = 8;
        else {
          // FIXME: This is X86 specific, use 32-bit alignment for long long.
          if (FD->getType()->isIntegerType() && TypeInfo.second > 32)
            FieldAlign = 32;
          else
            FieldAlign = TypeInfo.second;
        }

        // Check if we need to add padding to give the field the correct
        // alignment.
        if (RecordSize % FieldAlign + FieldSize > TypeSize)
          RecordSize = (RecordSize+FieldAlign-1) & ~(FieldAlign-1);

      } else {
        if (FD->getType()->isIncompleteType()) {
          // This must be a flexible array member; we can't directly
          // query getTypeInfo about these, so we figure it out here.
          // Flexible array members don't have any size, but they
          // have to be aligned appropriately for their element type.
        
          if (const AlignedAttr *AA = FD->getAttr<AlignedAttr>())
            FieldAlign = AA->getAlignment();
          else if (FieldIsPacked)
            FieldAlign = 8;
          else {
            const ArrayType* ATy = FD->getType()->getAsArrayType();
            FieldAlign = getTypeAlign(ATy->getElementType(), L);
          }
          FieldSize = 0;
        } else {
          std::pair<uint64_t, unsigned> FieldInfo = getTypeInfo(FD->getType(), L);
          FieldSize = FieldInfo.first;
        
          if (const AlignedAttr *AA = FD->getAttr<AlignedAttr>())
            FieldAlign = AA->getAlignment();
          else if (FieldIsPacked)
            FieldAlign = 8;
          else
            FieldAlign = FieldInfo.second;
        }

        // Round up the current record size to the field's alignment boundary.
        RecordSize = (RecordSize+FieldAlign-1) & ~(FieldAlign-1);
      }
      
      // Place this field at the current location.
      FieldOffsets[i] = RecordSize;
      
      // Reserve space for this field.
      RecordSize += FieldSize;
      
      // Remember max struct/class alignment.
      RecordAlign = std::max(RecordAlign, FieldAlign);
    }
    
    // Finally, round the size of the total struct up to the alignment of the
    // struct itself.
    RecordSize = (RecordSize+RecordAlign-1) & ~(RecordAlign-1);
  } else {
    // Union layout just puts each member at the start of the record.
    for (unsigned i = 0, e = D->getNumMembers(); i != e; ++i) {
      const FieldDecl *FD = D->getMember(i);
      std::pair<uint64_t, unsigned> FieldInfo = getTypeInfo(FD->getType(), L);
      uint64_t FieldSize = FieldInfo.first;
      unsigned FieldAlign = FieldInfo.second;
      
      // FIXME: This is X86 specific, use 32-bit alignment for long long.
      if (FD->getType()->isIntegerType() && FieldAlign > 32)
        FieldAlign = 32;

      // Round up the current record size to the field's alignment boundary.
      RecordSize = std::max(RecordSize, FieldSize);
      
      // Place this field at the start of the record.
      FieldOffsets[i] = 0;
      
      // Remember max struct/class alignment.
      RecordAlign = std::max(RecordAlign, FieldAlign);
    }
  }
  
  NewEntry->SetLayout(RecordSize, RecordAlign, FieldOffsets);
  return *NewEntry;
}

//===----------------------------------------------------------------------===//
//                   Type creation/memoization methods
//===----------------------------------------------------------------------===//

QualType ASTContext::getASQualType(QualType T, unsigned AddressSpace) {
  if (T.getCanonicalType().getAddressSpace() == AddressSpace)
    return T;
  
  // Type's cannot have multiple ASQuals, therefore we know we only have to deal
  // with CVR qualifiers from here on out.
  assert(T.getCanonicalType().getAddressSpace() == 0 &&
         "Type is already address space qualified");
  
  // Check if we've already instantiated an address space qual'd type of this
  // type.
  llvm::FoldingSetNodeID ID;
  ASQualType::Profile(ID, T.getTypePtr(), AddressSpace);      
  void *InsertPos = 0;
  if (ASQualType *ASQy = ASQualTypes.FindNodeOrInsertPos(ID, InsertPos))
    return QualType(ASQy, 0);
    
  // If the base type isn't canonical, this won't be a canonical type either,
  // so fill in the canonical type field.
  QualType Canonical;
  if (!T->isCanonical()) {
    Canonical = getASQualType(T.getCanonicalType(), AddressSpace);
    
    // Get the new insert position for the node we care about.
    ASQualType *NewIP = ASQualTypes.FindNodeOrInsertPos(ID, InsertPos);
    assert(NewIP == 0 && "Shouldn't be in the map!");
  }
  ASQualType *New = new ASQualType(T.getTypePtr(), Canonical, AddressSpace);
  ASQualTypes.InsertNode(New, InsertPos);
  Types.push_back(New);
  return QualType(New, T.getCVRQualifiers());
}


/// getComplexType - Return the uniqued reference to the type for a complex
/// number with the specified element type.
QualType ASTContext::getComplexType(QualType T) {
  // Unique pointers, to guarantee there is only one pointer of a particular
  // structure.
  llvm::FoldingSetNodeID ID;
  ComplexType::Profile(ID, T);
  
  void *InsertPos = 0;
  if (ComplexType *CT = ComplexTypes.FindNodeOrInsertPos(ID, InsertPos))
    return QualType(CT, 0);
  
  // If the pointee type isn't canonical, this won't be a canonical type either,
  // so fill in the canonical type field.
  QualType Canonical;
  if (!T->isCanonical()) {
    Canonical = getComplexType(T.getCanonicalType());
    
    // Get the new insert position for the node we care about.
    ComplexType *NewIP = ComplexTypes.FindNodeOrInsertPos(ID, InsertPos);
    assert(NewIP == 0 && "Shouldn't be in the map!");
  }
  ComplexType *New = new ComplexType(T, Canonical);
  Types.push_back(New);
  ComplexTypes.InsertNode(New, InsertPos);
  return QualType(New, 0);
}


/// getPointerType - Return the uniqued reference to the type for a pointer to
/// the specified type.
QualType ASTContext::getPointerType(QualType T) {
  // Unique pointers, to guarantee there is only one pointer of a particular
  // structure.
  llvm::FoldingSetNodeID ID;
  PointerType::Profile(ID, T);
  
  void *InsertPos = 0;
  if (PointerType *PT = PointerTypes.FindNodeOrInsertPos(ID, InsertPos))
    return QualType(PT, 0);
  
  // If the pointee type isn't canonical, this won't be a canonical type either,
  // so fill in the canonical type field.
  QualType Canonical;
  if (!T->isCanonical()) {
    Canonical = getPointerType(T.getCanonicalType());
   
    // Get the new insert position for the node we care about.
    PointerType *NewIP = PointerTypes.FindNodeOrInsertPos(ID, InsertPos);
    assert(NewIP == 0 && "Shouldn't be in the map!");
  }
  PointerType *New = new PointerType(T, Canonical);
  Types.push_back(New);
  PointerTypes.InsertNode(New, InsertPos);
  return QualType(New, 0);
}

/// getReferenceType - Return the uniqued reference to the type for a reference
/// to the specified type.
QualType ASTContext::getReferenceType(QualType T) {
  // Unique pointers, to guarantee there is only one pointer of a particular
  // structure.
  llvm::FoldingSetNodeID ID;
  ReferenceType::Profile(ID, T);

  void *InsertPos = 0;
  if (ReferenceType *RT = ReferenceTypes.FindNodeOrInsertPos(ID, InsertPos))
    return QualType(RT, 0);
  
  // If the referencee type isn't canonical, this won't be a canonical type
  // either, so fill in the canonical type field.
  QualType Canonical;
  if (!T->isCanonical()) {
    Canonical = getReferenceType(T.getCanonicalType());
   
    // Get the new insert position for the node we care about.
    ReferenceType *NewIP = ReferenceTypes.FindNodeOrInsertPos(ID, InsertPos);
    assert(NewIP == 0 && "Shouldn't be in the map!");
  }

  ReferenceType *New = new ReferenceType(T, Canonical);
  Types.push_back(New);
  ReferenceTypes.InsertNode(New, InsertPos);
  return QualType(New, 0);
}

/// getConstantArrayType - Return the unique reference to the type for an 
/// array of the specified element type.
QualType ASTContext::getConstantArrayType(QualType EltTy, 
                                          const llvm::APInt &ArySize,
                                          ArrayType::ArraySizeModifier ASM,
                                          unsigned EltTypeQuals) {
  llvm::FoldingSetNodeID ID;
  ConstantArrayType::Profile(ID, EltTy, ArySize);
      
  void *InsertPos = 0;
  if (ConstantArrayType *ATP = 
      ConstantArrayTypes.FindNodeOrInsertPos(ID, InsertPos))
    return QualType(ATP, 0);
  
  // If the element type isn't canonical, this won't be a canonical type either,
  // so fill in the canonical type field.
  QualType Canonical;
  if (!EltTy->isCanonical()) {
    Canonical = getConstantArrayType(EltTy.getCanonicalType(), ArySize, 
                                     ASM, EltTypeQuals);
    // Get the new insert position for the node we care about.
    ConstantArrayType *NewIP = 
      ConstantArrayTypes.FindNodeOrInsertPos(ID, InsertPos);

    assert(NewIP == 0 && "Shouldn't be in the map!");
  }
  
  ConstantArrayType *New = new ConstantArrayType(EltTy, Canonical, ArySize,
                                                 ASM, EltTypeQuals);
  ConstantArrayTypes.InsertNode(New, InsertPos);
  Types.push_back(New);
  return QualType(New, 0);
}

/// getVariableArrayType - Returns a non-unique reference to the type for a
/// variable array of the specified element type.
QualType ASTContext::getVariableArrayType(QualType EltTy, Expr *NumElts,
                                          ArrayType::ArraySizeModifier ASM,
                                          unsigned EltTypeQuals) {
  // Since we don't unique expressions, it isn't possible to unique VLA's
  // that have an expression provided for their size.

  VariableArrayType *New = new VariableArrayType(EltTy, QualType(), NumElts, 
                                                 ASM, EltTypeQuals);

  VariableArrayTypes.push_back(New);
  Types.push_back(New);
  return QualType(New, 0);
}

QualType ASTContext::getIncompleteArrayType(QualType EltTy,
                                            ArrayType::ArraySizeModifier ASM,
                                            unsigned EltTypeQuals) {
  llvm::FoldingSetNodeID ID;
  IncompleteArrayType::Profile(ID, EltTy);

  void *InsertPos = 0;
  if (IncompleteArrayType *ATP = 
       IncompleteArrayTypes.FindNodeOrInsertPos(ID, InsertPos))
    return QualType(ATP, 0);

  // If the element type isn't canonical, this won't be a canonical type
  // either, so fill in the canonical type field.
  QualType Canonical;

  if (!EltTy->isCanonical()) {
    Canonical = getIncompleteArrayType(EltTy.getCanonicalType(),
                                       ASM, EltTypeQuals);

    // Get the new insert position for the node we care about.
    IncompleteArrayType *NewIP =
      IncompleteArrayTypes.FindNodeOrInsertPos(ID, InsertPos);

    assert(NewIP == 0 && "Shouldn't be in the map!");
  }

  IncompleteArrayType *New = new IncompleteArrayType(EltTy, Canonical,
                                                     ASM, EltTypeQuals);

  IncompleteArrayTypes.InsertNode(New, InsertPos);
  Types.push_back(New);
  return QualType(New, 0);
}

/// getVectorType - Return the unique reference to a vector type of
/// the specified element type and size. VectorType must be a built-in type.
QualType ASTContext::getVectorType(QualType vecType, unsigned NumElts) {
  BuiltinType *baseType;
  
  baseType = dyn_cast<BuiltinType>(vecType.getCanonicalType().getTypePtr());
  assert(baseType != 0 && "getVectorType(): Expecting a built-in type");
         
  // Check if we've already instantiated a vector of this type.
  llvm::FoldingSetNodeID ID;
  VectorType::Profile(ID, vecType, NumElts, Type::Vector);      
  void *InsertPos = 0;
  if (VectorType *VTP = VectorTypes.FindNodeOrInsertPos(ID, InsertPos))
    return QualType(VTP, 0);

  // If the element type isn't canonical, this won't be a canonical type either,
  // so fill in the canonical type field.
  QualType Canonical;
  if (!vecType->isCanonical()) {
    Canonical = getVectorType(vecType.getCanonicalType(), NumElts);
    
    // Get the new insert position for the node we care about.
    VectorType *NewIP = VectorTypes.FindNodeOrInsertPos(ID, InsertPos);
    assert(NewIP == 0 && "Shouldn't be in the map!");
  }
  VectorType *New = new VectorType(vecType, NumElts, Canonical);
  VectorTypes.InsertNode(New, InsertPos);
  Types.push_back(New);
  return QualType(New, 0);
}

/// getOCUVectorType - Return the unique reference to an OCU vector type of
/// the specified element type and size. VectorType must be a built-in type.
QualType ASTContext::getOCUVectorType(QualType vecType, unsigned NumElts) {
  BuiltinType *baseType;
  
  baseType = dyn_cast<BuiltinType>(vecType.getCanonicalType().getTypePtr());
  assert(baseType != 0 && "getOCUVectorType(): Expecting a built-in type");
         
  // Check if we've already instantiated a vector of this type.
  llvm::FoldingSetNodeID ID;
  VectorType::Profile(ID, vecType, NumElts, Type::OCUVector);      
  void *InsertPos = 0;
  if (VectorType *VTP = VectorTypes.FindNodeOrInsertPos(ID, InsertPos))
    return QualType(VTP, 0);

  // If the element type isn't canonical, this won't be a canonical type either,
  // so fill in the canonical type field.
  QualType Canonical;
  if (!vecType->isCanonical()) {
    Canonical = getOCUVectorType(vecType.getCanonicalType(), NumElts);
    
    // Get the new insert position for the node we care about.
    VectorType *NewIP = VectorTypes.FindNodeOrInsertPos(ID, InsertPos);
    assert(NewIP == 0 && "Shouldn't be in the map!");
  }
  OCUVectorType *New = new OCUVectorType(vecType, NumElts, Canonical);
  VectorTypes.InsertNode(New, InsertPos);
  Types.push_back(New);
  return QualType(New, 0);
}

/// getFunctionTypeNoProto - Return a K&R style C function type like 'int()'.
///
QualType ASTContext::getFunctionTypeNoProto(QualType ResultTy) {
  // Unique functions, to guarantee there is only one function of a particular
  // structure.
  llvm::FoldingSetNodeID ID;
  FunctionTypeNoProto::Profile(ID, ResultTy);
  
  void *InsertPos = 0;
  if (FunctionTypeNoProto *FT = 
        FunctionTypeNoProtos.FindNodeOrInsertPos(ID, InsertPos))
    return QualType(FT, 0);
  
  QualType Canonical;
  if (!ResultTy->isCanonical()) {
    Canonical = getFunctionTypeNoProto(ResultTy.getCanonicalType());
    
    // Get the new insert position for the node we care about.
    FunctionTypeNoProto *NewIP =
      FunctionTypeNoProtos.FindNodeOrInsertPos(ID, InsertPos);
    assert(NewIP == 0 && "Shouldn't be in the map!");
  }
  
  FunctionTypeNoProto *New = new FunctionTypeNoProto(ResultTy, Canonical);
  Types.push_back(New);
  FunctionTypeNoProtos.InsertNode(New, InsertPos);
  return QualType(New, 0);
}

/// getFunctionType - Return a normal function type with a typed argument
/// list.  isVariadic indicates whether the argument list includes '...'.
QualType ASTContext::getFunctionType(QualType ResultTy, QualType *ArgArray,
                                     unsigned NumArgs, bool isVariadic) {
  // Unique functions, to guarantee there is only one function of a particular
  // structure.
  llvm::FoldingSetNodeID ID;
  FunctionTypeProto::Profile(ID, ResultTy, ArgArray, NumArgs, isVariadic);

  void *InsertPos = 0;
  if (FunctionTypeProto *FTP = 
        FunctionTypeProtos.FindNodeOrInsertPos(ID, InsertPos))
    return QualType(FTP, 0);
    
  // Determine whether the type being created is already canonical or not.  
  bool isCanonical = ResultTy->isCanonical();
  for (unsigned i = 0; i != NumArgs && isCanonical; ++i)
    if (!ArgArray[i]->isCanonical())
      isCanonical = false;

  // If this type isn't canonical, get the canonical version of it.
  QualType Canonical;
  if (!isCanonical) {
    llvm::SmallVector<QualType, 16> CanonicalArgs;
    CanonicalArgs.reserve(NumArgs);
    for (unsigned i = 0; i != NumArgs; ++i)
      CanonicalArgs.push_back(ArgArray[i].getCanonicalType());
    
    Canonical = getFunctionType(ResultTy.getCanonicalType(),
                                &CanonicalArgs[0], NumArgs,
                                isVariadic);
    
    // Get the new insert position for the node we care about.
    FunctionTypeProto *NewIP =
      FunctionTypeProtos.FindNodeOrInsertPos(ID, InsertPos);
    assert(NewIP == 0 && "Shouldn't be in the map!");
  }
  
  // FunctionTypeProto objects are not allocated with new because they have a
  // variable size array (for parameter types) at the end of them.
  FunctionTypeProto *FTP = 
    (FunctionTypeProto*)malloc(sizeof(FunctionTypeProto) + 
                               NumArgs*sizeof(QualType));
  new (FTP) FunctionTypeProto(ResultTy, ArgArray, NumArgs, isVariadic,
                              Canonical);
  Types.push_back(FTP);
  FunctionTypeProtos.InsertNode(FTP, InsertPos);
  return QualType(FTP, 0);
}

/// getTypedefType - Return the unique reference to the type for the
/// specified typename decl.
QualType ASTContext::getTypedefType(TypedefDecl *Decl) {
  if (Decl->TypeForDecl) return QualType(Decl->TypeForDecl, 0);
  
  QualType Canonical = Decl->getUnderlyingType().getCanonicalType();
  Decl->TypeForDecl = new TypedefType(Type::TypeName, Decl, Canonical);
  Types.push_back(Decl->TypeForDecl);
  return QualType(Decl->TypeForDecl, 0);
}

/// getObjCInterfaceType - Return the unique reference to the type for the
/// specified ObjC interface decl.
QualType ASTContext::getObjCInterfaceType(ObjCInterfaceDecl *Decl) {
  if (Decl->TypeForDecl) return QualType(Decl->TypeForDecl, 0);
  
  Decl->TypeForDecl = new ObjCInterfaceType(Type::ObjCInterface, Decl);
  Types.push_back(Decl->TypeForDecl);
  return QualType(Decl->TypeForDecl, 0);
}

/// getObjCQualifiedInterfaceType - Return a 
/// ObjCQualifiedInterfaceType type for the given interface decl and
/// the conforming protocol list.
QualType ASTContext::getObjCQualifiedInterfaceType(ObjCInterfaceDecl *Decl,
                       ObjCProtocolDecl **Protocols, unsigned NumProtocols) {
  llvm::FoldingSetNodeID ID;
  ObjCQualifiedInterfaceType::Profile(ID, Protocols, NumProtocols);
  
  void *InsertPos = 0;
  if (ObjCQualifiedInterfaceType *QT =
      ObjCQualifiedInterfaceTypes.FindNodeOrInsertPos(ID, InsertPos))
    return QualType(QT, 0);
  
  // No Match;
  ObjCQualifiedInterfaceType *QType =
    new ObjCQualifiedInterfaceType(Decl, Protocols, NumProtocols);
  Types.push_back(QType);
  ObjCQualifiedInterfaceTypes.InsertNode(QType, InsertPos);
  return QualType(QType, 0);
}

/// getObjCQualifiedIdType - Return a 
/// getObjCQualifiedIdType type for the 'id' decl and
/// the conforming protocol list.
QualType ASTContext::getObjCQualifiedIdType(QualType idType,
                                            ObjCProtocolDecl **Protocols, 
                                            unsigned NumProtocols) {
  llvm::FoldingSetNodeID ID;
  ObjCQualifiedIdType::Profile(ID, Protocols, NumProtocols);
  
  void *InsertPos = 0;
  if (ObjCQualifiedIdType *QT =
      ObjCQualifiedIdTypes.FindNodeOrInsertPos(ID, InsertPos))
    return QualType(QT, 0);
  
  // No Match;
  QualType Canonical;
  if (!idType->isCanonical()) {
    Canonical = getObjCQualifiedIdType(idType.getCanonicalType(), 
                                       Protocols, NumProtocols);
    ObjCQualifiedIdType *NewQT = 
      ObjCQualifiedIdTypes.FindNodeOrInsertPos(ID, InsertPos);
    assert(NewQT == 0 && "Shouldn't be in the map!");
  }
  
  ObjCQualifiedIdType *QType = 
    new ObjCQualifiedIdType(Canonical, Protocols, NumProtocols);
  Types.push_back(QType);
  ObjCQualifiedIdTypes.InsertNode(QType, InsertPos);
  return QualType(QType, 0);
}

/// getTypeOfExpr - Unlike many "get<Type>" functions, we can't unique
/// TypeOfExpr AST's (since expression's are never shared). For example,
/// multiple declarations that refer to "typeof(x)" all contain different
/// DeclRefExpr's. This doesn't effect the type checker, since it operates 
/// on canonical type's (which are always unique).
QualType ASTContext::getTypeOfExpr(Expr *tofExpr) {
  QualType Canonical = tofExpr->getType().getCanonicalType();
  TypeOfExpr *toe = new TypeOfExpr(tofExpr, Canonical);
  Types.push_back(toe);
  return QualType(toe, 0);
}

/// getTypeOfType -  Unlike many "get<Type>" functions, we don't unique
/// TypeOfType AST's. The only motivation to unique these nodes would be
/// memory savings. Since typeof(t) is fairly uncommon, space shouldn't be
/// an issue. This doesn't effect the type checker, since it operates 
/// on canonical type's (which are always unique).
QualType ASTContext::getTypeOfType(QualType tofType) {
  QualType Canonical = tofType.getCanonicalType();
  TypeOfType *tot = new TypeOfType(tofType, Canonical);
  Types.push_back(tot);
  return QualType(tot, 0);
}

/// getTagDeclType - Return the unique reference to the type for the
/// specified TagDecl (struct/union/class/enum) decl.
QualType ASTContext::getTagDeclType(TagDecl *Decl) {
  assert (Decl);

  // The decl stores the type cache.
  if (Decl->TypeForDecl) return QualType(Decl->TypeForDecl, 0);
  
  TagType* T = new TagType(Decl, QualType());
  Types.push_back(T);  
  Decl->TypeForDecl = T;

  return QualType(T, 0);
}

/// getSizeType - Return the unique type for "size_t" (C99 7.17), the result 
/// of the sizeof operator (C99 6.5.3.4p4). The value is target dependent and 
/// needs to agree with the definition in <stddef.h>. 
QualType ASTContext::getSizeType() const {
  // On Darwin, size_t is defined as a "long unsigned int". 
  // FIXME: should derive from "Target".
  return UnsignedLongTy; 
}

/// getWcharType - Return the unique type for "wchar_t" (C99 7.17), the
/// width of characters in wide strings, The value is target dependent and 
/// needs to agree with the definition in <stddef.h>.
QualType ASTContext::getWcharType() const {
  // On Darwin, wchar_t is defined as a "int". 
  // FIXME: should derive from "Target".
  return IntTy; 
}

/// getPointerDiffType - Return the unique type for "ptrdiff_t" (ref?)
/// defined in <stddef.h>. Pointer - pointer requires this (C99 6.5.6p9).
QualType ASTContext::getPointerDiffType() const {
  // On Darwin, ptrdiff_t is defined as a "int". This seems like a bug...
  // FIXME: should derive from "Target".
  return IntTy; 
}

/// getIntegerRank - Return an integer conversion rank (C99 6.3.1.1p1). This
/// routine will assert if passed a built-in type that isn't an integer or enum.
static int getIntegerRank(QualType t) {
  if (const TagType *TT = dyn_cast<TagType>(t.getCanonicalType())) {
    assert(TT->getDecl()->getKind() == Decl::Enum && "not an int or enum");
    return 4;
  }
  
  const BuiltinType *BT = t.getCanonicalType()->getAsBuiltinType();
  switch (BT->getKind()) {
  default:
    assert(0 && "getIntegerRank(): not a built-in integer");
  case BuiltinType::Bool:
    return 1;
  case BuiltinType::Char_S:
  case BuiltinType::Char_U:
  case BuiltinType::SChar:
  case BuiltinType::UChar:
    return 2;
  case BuiltinType::Short:
  case BuiltinType::UShort:
    return 3;
  case BuiltinType::Int:
  case BuiltinType::UInt:
    return 4;
  case BuiltinType::Long:
  case BuiltinType::ULong:
    return 5;
  case BuiltinType::LongLong:
  case BuiltinType::ULongLong:
    return 6;
  }
}

/// getFloatingRank - Return a relative rank for floating point types.
/// This routine will assert if passed a built-in type that isn't a float.
static int getFloatingRank(QualType T) {
  T = T.getCanonicalType();
  if (const ComplexType *CT = T->getAsComplexType())
    return getFloatingRank(CT->getElementType());
  
  switch (T->getAsBuiltinType()->getKind()) {
  default:  assert(0 && "getFloatingRank(): not a floating type");
  case BuiltinType::Float:      return FloatRank;
  case BuiltinType::Double:     return DoubleRank;
  case BuiltinType::LongDouble: return LongDoubleRank;
  }
}

/// getFloatingTypeOfSizeWithinDomain - Returns a real floating 
/// point or a complex type (based on typeDomain/typeSize). 
/// 'typeDomain' is a real floating point or complex type.
/// 'typeSize' is a real floating point or complex type.
QualType ASTContext::getFloatingTypeOfSizeWithinDomain(
  QualType typeSize, QualType typeDomain) const {
  if (typeDomain->isComplexType()) {
    switch (getFloatingRank(typeSize)) {
    default: assert(0 && "getFloatingRank(): illegal value for rank");
    case FloatRank:      return FloatComplexTy;
    case DoubleRank:     return DoubleComplexTy;
    case LongDoubleRank: return LongDoubleComplexTy;
    }
  }
  if (typeDomain->isRealFloatingType()) {
    switch (getFloatingRank(typeSize)) {
    default: assert(0 && "getFloatingRank(): illegal value for rank");
    case FloatRank:      return FloatTy;
    case DoubleRank:     return DoubleTy;
    case LongDoubleRank: return LongDoubleTy;
    }
  }
  assert(0 && "getFloatingTypeOfSizeWithinDomain(): illegal domain");
  //an invalid return value, but the assert
  //will ensure that this code is never reached.
  return VoidTy;
}

/// compareFloatingType - Handles 3 different combos: 
/// float/float, float/complex, complex/complex. 
/// If lt > rt, return 1. If lt == rt, return 0. If lt < rt, return -1.