//===--- CodeGenTypes.cpp - Type translation for LLVM CodeGen -------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file was developed by Chris Lattner and 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"

using namespace clang;
using namespace CodeGen;

CodeGenTypes::CodeGenTypes(ASTContext &Ctx, llvm::Module& M)
  : Context(Ctx), Target(Ctx.Target), TheModule(M) {
}

/// ConvertType - Convert the specified type to its LLVM form.
const llvm::Type *CodeGenTypes::ConvertType(QualType T) {
  // FIXME: Cache these, move the CodeGenModule, expand, etc.
  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:
      // FIXME: This is very strange.  We want scalars to be i1, but in memory
      // they can be i1 or i32.  Should the codegen handle this issue?
      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, SourceLocation())));
      
    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);
    return llvm::PointerType::get(ConvertType(P.getPointeeType())); 
  }
  case Type::Reference: {
    const ReferenceType &R = cast<ReferenceType>(Ty);
    return llvm::PointerType::get(ConvertType(R.getReferenceeType()));
  }
    
  case Type::VariableArray: {
    const VariableArrayType &A = cast<VariableArrayType>(Ty);
    assert(A.getSizeModifier() == ArrayType::Normal &&
           A.getIndexTypeQualifier() == 0 &&
           "FIXME: We only handle trivial array types so far!");
    if (A.getSizeExpr() == 0) {
      // int X[] -> [0 x int]
      return llvm::ArrayType::get(ConvertType(A.getElementType()), 0);
    } else {
      assert(0 && "FIXME: VLAs not implemented yet!");
    }
  }
  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));
      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, 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::Tagged:
    const TagType &TT = cast<TagType>(Ty);
    const TagDecl *TD = TT.getDecl();
    llvm::Type *&ResultType = TagDeclTypes[TD];
      
    if (ResultType)
      return ResultType;
    
    if (!TD->isDefinition()) {
      ResultType = llvm::OpaqueType::get();  
    } else if (TD->getKind() == Decl::Enum) {
      return ConvertType(cast<EnumDecl>(TD)->getIntegerType());
    } else if (TD->getKind() == Decl::Struct) {
      const RecordDecl *RD = cast<const RecordDecl>(TD);
      std::vector<const llvm::Type*> Fields;
      for (unsigned i = 0, e = RD->getNumMembers(); i != e; ++i)
        Fields.push_back(ConvertType(RD->getMember(i)->getType()));
      ResultType = llvm::StructType::get(Fields);
    } else if (TD->getKind() == Decl::Union) {
      const RecordDecl *RD = cast<const RecordDecl>(TD);
      // Just use the largest element of the union, breaking ties with the
      // highest aligned member.
      std::vector<const llvm::Type*> Fields;
      if (RD->getNumMembers() != 0) {
        std::pair<uint64_t, unsigned> MaxElt = 
          Context.getTypeInfo(RD->getMember(0)->getType(), SourceLocation());
        unsigned MaxEltNo = 0;
        
        for (unsigned i = 1, e = RD->getNumMembers(); i != e; ++i) {
          std::pair<uint64_t, unsigned> EltInfo = 
            Context.getTypeInfo(RD->getMember(i)->getType(), SourceLocation());
          if (EltInfo.first > MaxElt.first ||
              (EltInfo.first == MaxElt.first &&
               EltInfo.second > MaxElt.second)) {
            MaxElt = EltInfo;
            MaxEltNo = i;
          }
        }
        
        Fields.push_back(ConvertType(RD->getMember(MaxEltNo)->getType()));
      }        
      ResultType = llvm::StructType::get(Fields);
    } else {
      assert(0 && "FIXME: Implement tag decl kind!");
    }
          
    std::string TypeName(TD->getKindName());
    TypeName += '.';
    TypeName += TD->getName();
          
    TheModule.addTypeName(TypeName, ResultType);  
    return ResultType;
  }
  
  // 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
      ArgTys.push_back(llvm::PointerType::get(Ty));
  }
}