text: //===--- CGCall.cpp - Encapsulate calling convention details ----*- C++ -*-===//
  //
  //                     The LLVM Compiler Infrastructure
  //
  // This file is distributed under the University of Illinois Open Source
  // License. See LICENSE.TXT for details.
  //
  //===----------------------------------------------------------------------===//
  //
  // These classes wrap the information about a call or function
  // definition used to handle ABI compliancy.
  //
  //===----------------------------------------------------------------------===//
  
  #include "CGCall.h"
  #include "CGCXXABI.h"
  #include "ABIInfo.h"
  #include "CodeGenFunction.h"
  #include "CodeGenModule.h"
  #include "TargetInfo.h"
  #include "clang/Basic/TargetInfo.h"
  #include "clang/AST/Decl.h"
  #include "clang/AST/DeclCXX.h"
  #include "clang/AST/DeclObjC.h"
  #include "clang/Frontend/CodeGenOptions.h"
  #include "llvm/Attributes.h"
  #include "llvm/Support/CallSite.h"
  #include "llvm/Target/TargetData.h"
  #include "llvm/InlineAsm.h"
  #include "llvm/Transforms/Utils/Local.h"
  using namespace clang;
  using namespace CodeGen;
  
  /***/
  
  static unsigned ClangCallConvToLLVMCallConv(CallingConv CC) {
    switch (CC) {
    default: return llvm::CallingConv::C;
    case CC_X86StdCall: return llvm::CallingConv::X86_StdCall;
    case CC_X86FastCall: return llvm::CallingConv::X86_FastCall;
    case CC_X86ThisCall: return llvm::CallingConv::X86_ThisCall;
    case CC_AAPCS: return llvm::CallingConv::ARM_AAPCS;
    case CC_AAPCS_VFP: return llvm::CallingConv::ARM_AAPCS_VFP;
    // TODO: add support for CC_X86Pascal to llvm
    }
  }
  
  /// Derives the 'this' type for codegen purposes, i.e. ignoring method
  /// qualification.
  /// FIXME: address space qualification?
  static CanQualType GetThisType(ASTContext &Context, const CXXRecordDecl *RD) {
    QualType RecTy = Context.getTagDeclType(RD)->getCanonicalTypeInternal();
    return Context.getPointerType(CanQualType::CreateUnsafe(RecTy));
  }
  
  /// Returns the canonical formal type of the given C++ method.
  static CanQual<FunctionProtoType> GetFormalType(const CXXMethodDecl *MD) {
    return MD->getType()->getCanonicalTypeUnqualified()
             .getAs<FunctionProtoType>();
  }
  
  /// Returns the "extra-canonicalized" return type, which discards
  /// qualifiers on the return type.  Codegen doesn't care about them,
  /// and it makes ABI code a little easier to be able to assume that
  /// all parameter and return types are top-level unqualified.
  static CanQualType GetReturnType(QualType RetTy) {
    return RetTy->getCanonicalTypeUnqualified().getUnqualifiedType();
  }
  
  /// Arrange the argument and result information for a value of the
  /// given unprototyped function type.
  const CGFunctionInfo &
  CodeGenTypes::arrangeFunctionType(CanQual<FunctionNoProtoType> FTNP) {
    // When translating an unprototyped function type, always use a
    // variadic type.
    return arrangeFunctionType(FTNP->getResultType().getUnqualifiedType(),
                               ArrayRef<CanQualType>(),
                               FTNP->getExtInfo(),
                               RequiredArgs(0));
  }
  
  /// Arrange the argument and result information for a value of the
  /// given function type, on top of any implicit parameters already
  /// stored.
  static const CGFunctionInfo &arrangeFunctionType(CodeGenTypes &CGT,
                                    SmallVectorImpl<CanQualType> &argTypes,
                                               CanQual<FunctionProtoType> FTP) {
    RequiredArgs required = RequiredArgs::forPrototypePlus(FTP, argTypes.size());
    // FIXME: Kill copy.
    for (unsigned i = 0, e = FTP->getNumArgs(); i != e; ++i)
      argTypes.push_back(FTP->getArgType(i));
    CanQualType resultType = FTP->getResultType().getUnqualifiedType();
    return CGT.arrangeFunctionType(resultType, argTypes,
                                   FTP->getExtInfo(), required);
  }
  
  /// Arrange the argument and result information for a value of the
  /// given function type.
  const CGFunctionInfo &
  CodeGenTypes::arrangeFunctionType(CanQual<FunctionProtoType> FTP) {
    SmallVector<CanQualType, 16> argTypes;
    return ::arrangeFunctionType(*this, argTypes, FTP);
  }
  
  static CallingConv getCallingConventionForDecl(const Decl *D) {
    // Set the appropriate calling convention for the Function.
    if (D->hasAttr<StdCallAttr>())
      return CC_X86StdCall;
  
    if (D->hasAttr<FastCallAttr>())
      return CC_X86FastCall;
  
    if (D->hasAttr<ThisCallAttr>())
      return CC_X86ThisCall;
  
    if (D->hasAttr<PascalAttr>())
      return CC_X86Pascal;
  
    if (PcsAttr *PCS = D->getAttr<PcsAttr>())
      return (PCS->getPCS() == PcsAttr::AAPCS ? CC_AAPCS : CC_AAPCS_VFP);
  
    return CC_C;
  }
  
  /// Arrange the argument and result information for a call to an
  /// unknown C++ non-static member function of the given abstract type.
  /// The member function must be an ordinary function, i.e. not a
  /// constructor or destructor.
  const CGFunctionInfo &
  CodeGenTypes::arrangeCXXMethodType(const CXXRecordDecl *RD,
                                     const FunctionProtoType *FTP) {
    SmallVector<CanQualType, 16> argTypes;
  
    // Add the 'this' pointer.
    argTypes.push_back(GetThisType(Context, RD));
  
    return ::arrangeFunctionType(*this, argTypes,
                FTP->getCanonicalTypeUnqualified().getAs<FunctionProtoType>());
  }
  
  /// Arrange the argument and result information for a declaration or
  /// definition of the given C++ non-static member function.  The
  /// member function must be an ordinary function, i.e. not a
  /// constructor or destructor.
  const CGFunctionInfo &
  CodeGenTypes::arrangeCXXMethodDeclaration(const CXXMethodDecl *MD) {
    assert(!isa<CXXConstructorDecl>(MD) && "wrong method for contructors!");
    assert(!isa<CXXDestructorDecl>(MD) && "wrong method for destructors!");
  
    CanQual<FunctionProtoType> prototype = GetFormalType(MD);
  
    if (MD->isInstance()) {
      // The abstract case is perfectly fine.
      return arrangeCXXMethodType(MD->getParent(), prototype.getTypePtr());
    }
  
    return arrangeFunctionType(prototype);
  }
  
  /// Arrange the argument and result information for a declaration
  /// or definition to the given constructor variant.
  const CGFunctionInfo &
  CodeGenTypes::arrangeCXXConstructorDeclaration(const CXXConstructorDecl *D,
                                                 CXXCtorType ctorKind) {
    SmallVector<CanQualType, 16> argTypes;
    argTypes.push_back(GetThisType(Context, D->getParent()));
    CanQualType resultType = Context.VoidTy;
  
    TheCXXABI.BuildConstructorSignature(D, ctorKind, resultType, argTypes);
  
    CanQual<FunctionProtoType> FTP = GetFormalType(D);
  
    RequiredArgs required = RequiredArgs::forPrototypePlus(FTP, argTypes.size());
  
    // Add the formal parameters.
    for (unsigned i = 0, e = FTP->getNumArgs(); i != e; ++i)
      argTypes.push_back(FTP->getArgType(i));
  
    return arrangeFunctionType(resultType, argTypes, FTP->getExtInfo(), required);
  }
  
  /// Arrange the argument and result information for a declaration,
  /// definition, or call to the given destructor variant.  It so
  /// happens that all three cases produce the same information.
  const CGFunctionInfo &
  CodeGenTypes::arrangeCXXDestructor(const CXXDestructorDecl *D,
                                     CXXDtorType dtorKind) {
    SmallVector<CanQualType, 2> argTypes;
    argTypes.push_back(GetThisType(Context, D->getParent()));
    CanQualType resultType = Context.VoidTy;
  
    TheCXXABI.BuildDestructorSignature(D, dtorKind, resultType, argTypes);
  
    CanQual<FunctionProtoType> FTP = GetFormalType(D);
    assert(FTP->getNumArgs() == 0 && "dtor with formal parameters");
  
    return arrangeFunctionType(resultType, argTypes, FTP->getExtInfo(),
                               RequiredArgs::All);
  }
  
  /// Arrange the argument and result information for the declaration or
  /// definition of the given function.
  const CGFunctionInfo &
  CodeGenTypes::arrangeFunctionDeclaration(const FunctionDecl *FD) {
    if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD))
      if (MD->isInstance())
        return arrangeCXXMethodDeclaration(MD);
  
    CanQualType FTy = FD->getType()->getCanonicalTypeUnqualified();
  
    assert(isa<FunctionType>(FTy));
  
    // When declaring a function without a prototype, always use a
    // non-variadic type.
    if (isa<FunctionNoProtoType>(FTy)) {
      CanQual<FunctionNoProtoType> noProto = FTy.getAs<FunctionNoProtoType>();
      return arrangeFunctionType(noProto->getResultType(),
                                 ArrayRef<CanQualType>(),
                                 noProto->getExtInfo(),
                                 RequiredArgs::All);
    }
  
    assert(isa<FunctionProtoType>(FTy));
    return arrangeFunctionType(FTy.getAs<FunctionProtoType>());
  }
  
  /// Arrange the argument and result information for the declaration or
  /// definition of an Objective-C method.
  const CGFunctionInfo &
  CodeGenTypes::arrangeObjCMethodDeclaration(const ObjCMethodDecl *MD) {
    // It happens that this is the same as a call with no optional
    // arguments, except also using the formal 'self' type.
    return arrangeObjCMessageSendSignature(MD, MD->getSelfDecl()->getType());
  }
  
  /// Arrange the argument and result information for the function type
  /// through which to perform a send to the given Objective-C method,
  /// using the given receiver type.  The receiver type is not always
  /// the 'self' type of the method or even an Objective-C pointer type.
  /// This is *not* the right method for actually performing such a
  /// message send, due to the possibility of optional arguments.
  const CGFunctionInfo &
  CodeGenTypes::arrangeObjCMessageSendSignature(const ObjCMethodDecl *MD,
                                                QualType receiverType) {
    SmallVector<CanQualType, 16> argTys;
    argTys.push_back(Context.getCanonicalParamType(receiverType));
    argTys.push_back(Context.getCanonicalParamType(Context.getObjCSelType()));
    // FIXME: Kill copy?
    for (ObjCMethodDecl::param_const_iterator i = MD->param_begin(),
           e = MD->param_end(); i != e; ++i) {
      argTys.push_back(Context.getCanonicalParamType((*i)->getType()));
    }
  
    FunctionType::ExtInfo einfo;
    einfo = einfo.withCallingConv(getCallingConventionForDecl(MD));
  
    if (getContext().getLangOpts().ObjCAutoRefCount &&
        MD->hasAttr<NSReturnsRetainedAttr>())
      einfo = einfo.withProducesResult(true);
  
    RequiredArgs required =
      (MD->isVariadic() ? RequiredArgs(argTys.size()) : RequiredArgs::All);
  
    return arrangeFunctionType(GetReturnType(MD->getResultType()), argTys,
                               einfo, required);
  }
  
  const CGFunctionInfo &
  CodeGenTypes::arrangeGlobalDeclaration(GlobalDecl GD) {
    // FIXME: Do we need to handle ObjCMethodDecl?
    const FunctionDecl *FD = cast<FunctionDecl>(GD.getDecl());
  
    if (const CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(FD))
      return arrangeCXXConstructorDeclaration(CD, GD.getCtorType());
  
    if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(FD))
      return arrangeCXXDestructor(DD, GD.getDtorType());
  
    return arrangeFunctionDeclaration(FD);
  }
  
  /// Figure out the rules for calling a function with the given formal
  /// type using the given arguments.  The arguments are necessary
  /// because the function might be unprototyped, in which case it's
  /// target-dependent in crazy ways.
  const CGFunctionInfo &
  CodeGenTypes::arrangeFunctionCall(const CallArgList &args,
                                    const FunctionType *fnType) {
    RequiredArgs required = RequiredArgs::All;
    if (const FunctionProtoType *proto = dyn_cast<FunctionProtoType>(fnType)) {
      if (proto->isVariadic())
        required = RequiredArgs(proto->getNumArgs());
    } else if (CGM.getTargetCodeGenInfo()
                 .isNoProtoCallVariadic(args, cast<FunctionNoProtoType>(fnType))) {
      required = RequiredArgs(0);
    }
  
    return arrangeFunctionCall(fnType->getResultType(), args,
                               fnType->getExtInfo(), required);
  }
  
  const CGFunctionInfo &
  CodeGenTypes::arrangeFunctionCall(QualType resultType,
                                    const CallArgList &args,
                                    const FunctionType::ExtInfo &info,
                                    RequiredArgs required) {
    // FIXME: Kill copy.
    SmallVector<CanQualType, 16> argTypes;
    for (CallArgList::const_iterator i = args.begin(), e = args.end();
         i != e; ++i)
      argTypes.push_back(Context.getCanonicalParamType(i->Ty));
    return arrangeFunctionType(GetReturnType(resultType), argTypes, info,
                               required);
  }
  
  const CGFunctionInfo &
  CodeGenTypes::arrangeFunctionDeclaration(QualType resultType,
                                           const FunctionArgList &args,
                                           const FunctionType::ExtInfo &info,
                                           bool isVariadic) {
    // FIXME: Kill copy.
    SmallVector<CanQualType, 16> argTypes;
    for (FunctionArgList::const_iterator i = args.begin(), e = args.end();
         i != e; ++i)
      argTypes.push_back(Context.getCanonicalParamType((*i)->getType()));
  
    RequiredArgs required =
      (isVariadic ? RequiredArgs(args.size()) : RequiredArgs::All);
    return arrangeFunctionType(GetReturnType(resultType), argTypes, info,
                               required);
  }
  
  const CGFunctionInfo &CodeGenTypes::arrangeNullaryFunction() {
    return arrangeFunctionType(getContext().VoidTy, ArrayRef<CanQualType>(),
                               FunctionType::ExtInfo(), RequiredArgs::All);
  }
  
  /// Arrange the argument and result information for an abstract value
  /// of a given function type.  This is the method which all of the
  /// above functions ultimately defer to.
  const CGFunctionInfo &
  CodeGenTypes::arrangeFunctionType(CanQualType resultType,
                                    ArrayRef<CanQualType> argTypes,
                                    const FunctionType::ExtInfo &info,
                                    RequiredArgs required) {
  #ifndef NDEBUG
    for (ArrayRef<CanQualType>::const_iterator
           I = argTypes.begin(), E = argTypes.end(); I != E; ++I)
      assert(I->isCanonicalAsParam());
  #endif
  
    unsigned CC = ClangCallConvToLLVMCallConv(info.getCC());
  
    // Lookup or create unique function info.
    llvm::FoldingSetNodeID ID;
    CGFunctionInfo::Profile(ID, info, required, resultType, argTypes);
  
    void *insertPos = 0;
    CGFunctionInfo *FI = FunctionInfos.FindNodeOrInsertPos(ID, insertPos);
    if (FI)
      return *FI;
  
    // Construct the function info.  We co-allocate the ArgInfos.
    FI = CGFunctionInfo::create(CC, info, resultType, argTypes, required);
    FunctionInfos.InsertNode(FI, insertPos);
  
    bool inserted = FunctionsBeingProcessed.insert(FI); (void)inserted;
    assert(inserted && "Recursively being processed?");
    
    // Compute ABI information.
    getABIInfo().computeInfo(*FI);
  
    // Loop over all of the computed argument and return value info.  If any of
    // them are direct or extend without a specified coerce type, specify the
    // default now.
    ABIArgInfo &retInfo = FI->getReturnInfo();
    if (retInfo.canHaveCoerceToType() && retInfo.getCoerceToType() == 0)
      retInfo.setCoerceToType(ConvertType(FI->getReturnType()));
  
    for (CGFunctionInfo::arg_iterator I = FI->arg_begin(), E = FI->arg_end();
         I != E; ++I)
      if (I->info.canHaveCoerceToType() && I->info.getCoerceToType() == 0)
        I->info.setCoerceToType(ConvertType(I->type));
  
    bool erased = FunctionsBeingProcessed.erase(FI); (void)erased;
    assert(erased && "Not in set?");
    
    return *FI;
  }
  
  CGFunctionInfo *CGFunctionInfo::create(unsigned llvmCC,
                                         const FunctionType::ExtInfo &info,
                                         CanQualType resultType,
                                         ArrayRef<CanQualType> argTypes,
                                         RequiredArgs required) {
    void *buffer = operator new(sizeof(CGFunctionInfo) +
                                sizeof(ArgInfo) * (argTypes.size() + 1));
    CGFunctionInfo *FI = new(buffer) CGFunctionInfo();
    FI->CallingConvention = llvmCC;
    FI->EffectiveCallingConvention = llvmCC;
    FI->ASTCallingConvention = info.getCC();
    FI->NoReturn = info.getNoReturn();
    FI->ReturnsRetained = info.getProducesResult();
    FI->Required = required;
    FI->HasRegParm = info.getHasRegParm();
    FI->RegParm = info.getRegParm();
    FI->NumArgs = argTypes.size();
    FI->getArgsBuffer()[0].type = resultType;
    for (unsigned i = 0, e = argTypes.size(); i != e; ++i)
      FI->getArgsBuffer()[i + 1].type = argTypes[i];
    return FI;
  }
  
  /***/
  
  void CodeGenTypes::GetExpandedTypes(QualType type,
                       SmallVectorImpl<llvm::Type*> &expandedTypes) {
    if (const ConstantArrayType *AT = Context.getAsConstantArrayType(type)) {
      uint64_t NumElts = AT->getSize().getZExtValue();
      for (uint64_t Elt = 0; Elt < NumElts; ++Elt)
        GetExpandedTypes(AT->getElementType(), expandedTypes);
    } else if (const RecordType *RT = type->getAs<RecordType>()) {
      const RecordDecl *RD = RT->getDecl();
      assert(!RD->hasFlexibleArrayMember() &&
             "Cannot expand structure with flexible array.");
      if (RD->isUnion()) {
        // Unions can be here only in degenerative cases - all the fields are same
        // after flattening. Thus we have to use the "largest" field.
        const FieldDecl *LargestFD = 0;
        CharUnits UnionSize = CharUnits::Zero();
  
        for (RecordDecl::field_iterator i = RD->field_begin(), e = RD->field_end();
             i != e; ++i) {
          const FieldDecl *FD = *i;
          assert(!FD->isBitField() &&
                 "Cannot expand structure with bit-field members.");
          CharUnits FieldSize = getContext().getTypeSizeInChars(FD->getType());
          if (UnionSize < FieldSize) {
            UnionSize = FieldSize;
            LargestFD = FD;
          }
        }
        if (LargestFD)
          GetExpandedTypes(LargestFD->getType(), expandedTypes);
      } else {
        for (RecordDecl::field_iterator i = RD->field_begin(), e = RD->field_end();
             i != e; ++i) {
          const FieldDecl *FD = *i;
          assert(!FD->isBitField() &&
                 "Cannot expand structure with bit-field members.");
          GetExpandedTypes(FD->getType(), expandedTypes);
        }
      }
    } else if (const ComplexType *CT = type->getAs<ComplexType>()) {
      llvm::Type *EltTy = ConvertType(CT->getElementType());
      expandedTypes.push_back(EltTy);
      expandedTypes.push_back(EltTy);
    } else
      expandedTypes.push_back(ConvertType(type));
  }
  
  llvm::Function::arg_iterator
  CodeGenFunction::ExpandTypeFromArgs(QualType Ty, LValue LV,
                                      llvm::Function::arg_iterator AI) {
    assert(LV.isSimple() &&
           "Unexpected non-simple lvalue during struct expansion.");
  
    if (const ConstantArrayType *AT = getContext().getAsConstantArrayType(Ty)) {
      unsigned NumElts = AT->getSize().getZExtValue();
      QualType EltTy = AT->getElementType();
      for (unsigned Elt = 0; Elt < NumElts; ++Elt) {
        llvm::Value *EltAddr = Builder.CreateConstGEP2_32(LV.getAddress(), 0, Elt);
        LValue LV = MakeAddrLValue(EltAddr, EltTy);
        AI = ExpandTypeFromArgs(EltTy, LV, AI);
      }
    } else if (const RecordType *RT = Ty->getAs<RecordType>()) {
      RecordDecl *RD = RT->getDecl();
      if (RD->isUnion()) {
        // Unions can be here only in degenerative cases - all the fields are same
        // after flattening. Thus we have to use the "largest" field.
        const FieldDecl *LargestFD = 0;
        CharUnits UnionSize = CharUnits::Zero();
  
        for (RecordDecl::field_iterator i = RD->field_begin(), e = RD->field_end();
             i != e; ++i) {
          const FieldDecl *FD = *i;
          assert(!FD->isBitField() &&
                 "Cannot expand structure with bit-field members.");
          CharUnits FieldSize = getContext().getTypeSizeInChars(FD->getType());
          if (UnionSize < FieldSize) {
            UnionSize = FieldSize;
            LargestFD = FD;
          }
        }
        if (LargestFD) {
          // FIXME: What are the right qualifiers here?
          LValue SubLV = EmitLValueForField(LV, LargestFD);
          AI = ExpandTypeFromArgs(LargestFD->getType(), SubLV, AI);
        }
      } else {
        for (RecordDecl::field_iterator i = RD->field_begin(), e = RD->field_end();
             i != e; ++i) {
          FieldDecl *FD = *i;
          QualType FT = FD->getType();
  
          // FIXME: What are the right qualifiers here?
          LValue SubLV = EmitLValueForField(LV, FD);
          AI = ExpandTypeFromArgs(FT, SubLV, AI);
        }
      }
    } else if (const ComplexType *CT = Ty->getAs<ComplexType>()) {
      QualType EltTy = CT->getElementType();
      llvm::Value *RealAddr = Builder.CreateStructGEP(LV.getAddress(), 0, "real");
      EmitStoreThroughLValue(RValue::get(AI++), MakeAddrLValue(RealAddr, EltTy));
      llvm::Value *ImagAddr = Builder.CreateStructGEP(LV.getAddress(), 1, "imag");
      EmitStoreThroughLValue(RValue::get(AI++), MakeAddrLValue(ImagAddr, EltTy));
    } else {
      EmitStoreThroughLValue(RValue::get(AI), LV);
      ++AI;
    }
  
    return AI;
  }
  
  /// EnterStructPointerForCoercedAccess - Given a struct pointer that we are
  /// accessing some number of bytes out of it, try to gep into the struct to get
  /// at its inner goodness.  Dive as deep as possible without entering an element
  /// with an in-memory size smaller than DstSize.
  static llvm::Value *
  EnterStructPointerForCoercedAccess(llvm::Value *SrcPtr,
                                     llvm::StructType *SrcSTy,
                                     uint64_t DstSize, CodeGenFunction &CGF) {
    // We can't dive into a zero-element struct.
    if (SrcSTy->getNumElements() == 0) return SrcPtr;
  
    llvm::Type *FirstElt = SrcSTy->getElementType(0);
  
    // If the first elt is at least as large as what we're looking for, or if the
    // first element is the same size as the whole struct, we can enter it.
    uint64_t FirstEltSize =
      CGF.CGM.getTargetData().getTypeAllocSize(FirstElt);
    if (FirstEltSize < DstSize &&
        FirstEltSize < CGF.CGM.getTargetData().getTypeAllocSize(SrcSTy))
      return SrcPtr;
  
    // GEP into the first element.
    SrcPtr = CGF.Builder.CreateConstGEP2_32(SrcPtr, 0, 0, "coerce.dive");
  
    // If the first element is a struct, recurse.
    llvm::Type *SrcTy =
      cast<llvm::PointerType>(SrcPtr->getType())->getElementType();
    if (llvm::StructType *SrcSTy = dyn_cast<llvm::StructType>(SrcTy))
      return EnterStructPointerForCoercedAccess(SrcPtr, SrcSTy, DstSize, CGF);
  
    return SrcPtr;
  }
  
  /// CoerceIntOrPtrToIntOrPtr - Convert a value Val to the specific Ty where both
  /// are either integers or pointers.  This does a truncation of the value if it
  /// is too large or a zero extension if it is too small.
  static llvm::Value *CoerceIntOrPtrToIntOrPtr(llvm::Value *Val,
                                               llvm::Type *Ty,
                                               CodeGenFunction &CGF) {
    if (Val->getType() == Ty)
      return Val;
  
    if (isa<llvm::PointerType>(Val->getType())) {
      // If this is Pointer->Pointer avoid conversion to and from int.
      if (isa<llvm::PointerType>(Ty))
        return CGF.Builder.CreateBitCast(Val, Ty, "coerce.val");
  
      // Convert the pointer to an integer so we can play with its width.
      Val = CGF.Builder.CreatePtrToInt(Val, CGF.IntPtrTy, "coerce.val.pi");
    }
  
    llvm::Type *DestIntTy = Ty;
    if (isa<llvm::PointerType>(DestIntTy))
      DestIntTy = CGF.IntPtrTy;
  
    if (Val->getType() != DestIntTy)
      Val = CGF.Builder.CreateIntCast(Val, DestIntTy, false, "coerce.val.ii");
  
    if (isa<llvm::PointerType>(Ty))
      Val = CGF.Builder.CreateIntToPtr(Val, Ty, "coerce.val.ip");
    return Val;
  }
  
  
  
  /// CreateCoercedLoad - Create a load from \arg SrcPtr interpreted as
  /// a pointer to an object of type \arg Ty.
  ///
  /// This safely handles the case when the src type is smaller than the
  /// destination type; in this situation the values of bits which not
  /// present in the src are undefined.
  static llvm::Value *CreateCoercedLoad(llvm::Value *SrcPtr,
                                        llvm::Type *Ty,
                                        CodeGenFunction &CGF) {
    llvm::Type *SrcTy =
      cast<llvm::PointerType>(SrcPtr->getType())->getElementType();
  
    // If SrcTy and Ty are the same, just do a load.
    if (SrcTy == Ty)
      return CGF.Builder.CreateLoad(SrcPtr);
  
    uint64_t DstSize = CGF.CGM.getTargetData().getTypeAllocSize(Ty);
  
    if (llvm::StructType *SrcSTy = dyn_cast<llvm::StructType>(SrcTy)) {
      SrcPtr = EnterStructPointerForCoercedAccess(SrcPtr, SrcSTy, DstSize, CGF);
      SrcTy = cast<llvm::PointerType>(SrcPtr->getType())->getElementType();
    }
  
    uint64_t SrcSize = CGF.CGM.getTargetData().getTypeAllocSize(SrcTy);
  
    // If the source and destination are integer or pointer types, just do an
    // extension or truncation to the desired type.
    if ((isa<llvm::IntegerType>(Ty) || isa<llvm::PointerType>(Ty)) &&
        (isa<llvm::IntegerType>(SrcTy) || isa<llvm::PointerType>(SrcTy))) {
      llvm::LoadInst *Load = CGF.Builder.CreateLoad(SrcPtr);
      return CoerceIntOrPtrToIntOrPtr(Load, Ty, CGF);
    }
  
    // If load is legal, just bitcast the src pointer.
    if (SrcSize >= DstSize) {
      // Generally SrcSize is never greater than DstSize, since this means we are
      // losing bits. However, this can happen in cases where the structure has
      // additional padding, for example due to a user specified alignment.
      //
      // FIXME: Assert that we aren't truncating non-padding bits when have access
      // to that information.
      llvm::Value *Casted =
        CGF.Builder.CreateBitCast(SrcPtr, llvm::PointerType::getUnqual(Ty));
      llvm::LoadInst *Load = CGF.Builder.CreateLoad(Casted);
      // FIXME: Use better alignment / avoid requiring aligned load.
      Load->setAlignment(1);
      return Load;
    }
  
    // Otherwise do coercion through memory. This is stupid, but
    // simple.
    llvm::Value *Tmp = CGF.CreateTempAlloca(Ty);
    llvm::Value *Casted =
      CGF.Builder.CreateBitCast(Tmp, llvm::PointerType::getUnqual(SrcTy));
    llvm::StoreInst *Store =
      CGF.Builder.CreateStore(CGF.Builder.CreateLoad(SrcPtr), Casted);
    // FIXME: Use better alignment / avoid requiring aligned store.
    Store->setAlignment(1);
    return CGF.Builder.CreateLoad(Tmp);
  }
  
  // Function to store a first-class aggregate into memory.  We prefer to
  // store the elements rather than the aggregate to be more friendly to
  // fast-isel.
  // FIXME: Do we need to recurse here?
  static void BuildAggStore(CodeGenFunction &CGF, llvm::Value *Val,
                            llvm::Value *DestPtr, bool DestIsVolatile,
                            bool LowAlignment) {
    // Prefer scalar stores to first-class aggregate stores.
    if (llvm::StructType *STy =
          dyn_cast<llvm::StructType>(Val->getType())) {
      for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
        llvm::Value *EltPtr = CGF.Builder.CreateConstGEP2_32(DestPtr, 0, i);
        llvm::Value *Elt = CGF.Builder.CreateExtractValue(Val, i);
        llvm::StoreInst *SI = CGF.Builder.CreateStore(Elt, EltPtr,
                                                      DestIsVolatile);
        if (LowAlignment)
          SI->setAlignment(1);
      }
    } else {
      llvm::StoreInst *SI = CGF.Builder.CreateStore(Val, DestPtr, DestIsVolatile);
      if (LowAlignment)
        SI->setAlignment(1);
    }
  }
  
  /// CreateCoercedStore - Create a store to \arg DstPtr from \arg Src,
  /// where the source and destination may have different types.
  ///
  /// This safely handles the case when the src type is larger than the
  /// destination type; the upper bits of the src will be lost.
  static void CreateCoercedStore(llvm::Value *Src,
                                 llvm::Value *DstPtr,
                                 bool DstIsVolatile,
                                 CodeGenFunction &CGF) {
    llvm::Type *SrcTy = Src->getType();
    llvm::Type *DstTy =
      cast<llvm::PointerType>(DstPtr->getType())->getElementType();
    if (SrcTy == DstTy) {
      CGF.Builder.CreateStore(Src, DstPtr, DstIsVolatile);
      return;
    }
  
    uint64_t SrcSize = CGF.CGM.getTargetData().getTypeAllocSize(SrcTy);
  
    if (llvm::StructType *DstSTy = dyn_cast<llvm::StructType>(DstTy)) {
      DstPtr = EnterStructPointerForCoercedAccess(DstPtr, DstSTy, SrcSize, CGF);
      DstTy = cast<llvm::PointerType>(DstPtr->getType())->getElementType();
    }
  
    // If the source and destination are integer or pointer types, just do an
    // extension or truncation to the desired type.
    if ((isa<llvm::IntegerType>(SrcTy) || isa<llvm::PointerType>(SrcTy)) &&
        (isa<llvm::IntegerType>(DstTy) || isa<llvm::PointerType>(DstTy))) {
      Src = CoerceIntOrPtrToIntOrPtr(Src, DstTy, CGF);
      CGF.Builder.CreateStore(Src, DstPtr, DstIsVolatile);
      return;
    }
  
    uint64_t DstSize = CGF.CGM.getTargetData().getTypeAllocSize(DstTy);
  
    // If store is legal, just bitcast the src pointer.
    if (SrcSize <= DstSize) {
      llvm::Value *Casted =
        CGF.Builder.CreateBitCast(DstPtr, llvm::PointerType::getUnqual(SrcTy));
      // FIXME: Use better alignment / avoid requiring aligned store.
      BuildAggStore(CGF, Src, Casted, DstIsVolatile, true);
    } else {
      // Otherwise do coercion through memory. This is stupid, but
      // simple.
  
      // Generally SrcSize is never greater than DstSize, since this means we are
      // losing bits. However, this can happen in cases where the structure has
      // additional padding, for example due to a user specified alignment.
      //
      // FIXME: Assert that we aren't truncating non-padding bits when have access
      // to that information.
      llvm::Value *Tmp = CGF.CreateTempAlloca(SrcTy);
      CGF.Builder.CreateStore(Src, Tmp);
      llvm::Value *Casted =
        CGF.Builder.CreateBitCast(Tmp, llvm::PointerType::getUnqual(DstTy));
      llvm::LoadInst *Load = CGF.Builder.CreateLoad(Casted);
      // FIXME: Use better alignment / avoid requiring aligned load.
      Load->setAlignment(1);
      CGF.Builder.CreateStore(Load, DstPtr, DstIsVolatile);
    }
  }
  
  /***/
  
  bool CodeGenModule::ReturnTypeUsesSRet(const CGFunctionInfo &FI) {
    return FI.getReturnInfo().isIndirect();
  }
  
  bool CodeGenModule::ReturnTypeUsesFPRet(QualType ResultType) {
    if (const BuiltinType *BT = ResultType->getAs<BuiltinType>()) {
      switch (BT->getKind()) {
      default:
        return false;
      case BuiltinType::Float:
        return getContext().getTargetInfo().useObjCFPRetForRealType(TargetInfo::Float);
      case BuiltinType::Double:
        return getContext().getTargetInfo().useObjCFPRetForRealType(TargetInfo::Double);
      case BuiltinType::LongDouble:
        return getContext().getTargetInfo().useObjCFPRetForRealType(
          TargetInfo::LongDouble);
      }
    }
  
    return false;
  }
  
  bool CodeGenModule::ReturnTypeUsesFP2Ret(QualType ResultType) {
    if (const ComplexType *CT = ResultType->getAs<ComplexType>()) {
      if (const BuiltinType *BT = CT->getElementType()->getAs<BuiltinType>()) {
        if (BT->getKind() == BuiltinType::LongDouble)
          return getContext().getTargetInfo().useObjCFP2RetForComplexLongDouble();
      }
    }
  
    return false;
  }
  
  llvm::FunctionType *CodeGenTypes::GetFunctionType(GlobalDecl GD) {
    const CGFunctionInfo &FI = arrangeGlobalDeclaration(GD);
    return GetFunctionType(FI);
  }
  
  llvm::FunctionType *
  CodeGenTypes::GetFunctionType(const CGFunctionInfo &FI) {
    
    bool Inserted = FunctionsBeingProcessed.insert(&FI); (void)Inserted;
    assert(Inserted && "Recursively being processed?");
    
    SmallVector<llvm::Type*, 8> argTypes;
    llvm::Type *resultType = 0;
  
    const ABIArgInfo &retAI = FI.getReturnInfo();
    switch (retAI.getKind()) {
    case ABIArgInfo::Expand:
      llvm_unreachable("Invalid ABI kind for return argument");
  
    case ABIArgInfo::Extend:
    case ABIArgInfo::Direct:
      resultType = retAI.getCoerceToType();
      break;
  
    case ABIArgInfo::Indirect: {
      assert(!retAI.getIndirectAlign() && "Align unused on indirect return.");
      resultType = llvm::Type::getVoidTy(getLLVMContext());
  
      QualType ret = FI.getReturnType();
      llvm::Type *ty = ConvertType(ret);
      unsigned addressSpace = Context.getTargetAddressSpace(ret);
      argTypes.push_back(llvm::PointerType::get(ty, addressSpace));
      break;
    }
  
    case ABIArgInfo::Ignore:
      resultType = llvm::Type::getVoidTy(getLLVMContext());
      break;
    }
  
    for (CGFunctionInfo::const_arg_iterator it = FI.arg_begin(),
           ie = FI.arg_end(); it != ie; ++it) {
      const ABIArgInfo &argAI = it->info;
  
      switch (argAI.getKind()) {
      case ABIArgInfo::Ignore:
        break;
  
      case ABIArgInfo::Indirect: {
        // indirect arguments are always on the stack, which is addr space #0.
        llvm::Type *LTy = ConvertTypeForMem(it->type);
        argTypes.push_back(LTy->getPointerTo());
        break;
      }
  
      case ABIArgInfo::Extend:
      case ABIArgInfo::Direct: {
        // Insert a padding type to ensure proper alignment.
        if (llvm::Type *PaddingType = argAI.getPaddingType())
          argTypes.push_back(PaddingType);
        // If the coerce-to type is a first class aggregate, flatten it.  Either
        // way is semantically identical, but fast-isel and the optimizer
        // generally likes scalar values better than FCAs.
        llvm::Type *argType = argAI.getCoerceToType();
        if (llvm::StructType *st = dyn_cast<llvm::StructType>(argType)) {
          for (unsigned i = 0, e = st->getNumElements(); i != e; ++i)
            argTypes.push_back(st->getElementType(i));
        } else {
          argTypes.push_back(argType);
        }
        break;
      }
  
      case ABIArgInfo::Expand:
        GetExpandedTypes(it->type, argTypes);
        break;
      }
    }
  
    bool Erased = FunctionsBeingProcessed.erase(&FI); (void)Erased;
    assert(Erased && "Not in set?");
    
    return llvm::FunctionType::get(resultType, argTypes, FI.isVariadic());
  }
  
  llvm::Type *CodeGenTypes::GetFunctionTypeForVTable(GlobalDecl GD) {
    const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
    const FunctionProtoType *FPT = MD->getType()->getAs<FunctionProtoType>();
  
    if (!isFuncTypeConvertible(FPT))
      return llvm::StructType::get(getLLVMContext());
      
    const CGFunctionInfo *Info;
    if (isa<CXXDestructorDecl>(MD))
      Info = &arrangeCXXDestructor(cast<CXXDestructorDecl>(MD), GD.getDtorType());
    else
      Info = &arrangeCXXMethodDeclaration(MD);
    return GetFunctionType(*Info);
  }
  
  void CodeGenModule::ConstructAttributeList(const CGFunctionInfo &FI,
                                             const Decl *TargetDecl,
                                             AttributeListType &PAL,
                                             unsigned &CallingConv) {
    llvm::Attributes FuncAttrs;
    llvm::Attributes RetAttrs;
  
    CallingConv = FI.getEffectiveCallingConvention();
  
    if (FI.isNoReturn())
      FuncAttrs |= llvm::Attribute::NoReturn;
  
    // FIXME: handle sseregparm someday...
    if (TargetDecl) {
      if (TargetDecl->hasAttr<ReturnsTwiceAttr>())
        FuncAttrs |= llvm::Attribute::ReturnsTwice;
      if (TargetDecl->hasAttr<NoThrowAttr>())
        FuncAttrs |= llvm::Attribute::NoUnwind;
      else if (const FunctionDecl *Fn = dyn_cast<FunctionDecl>(TargetDecl)) {
        const FunctionProtoType *FPT = Fn->getType()->getAs<FunctionProtoType>();
        if (FPT && FPT->isNothrow(getContext()))
          FuncAttrs |= llvm::Attribute::NoUnwind;
      }
  
      if (TargetDecl->hasAttr<NoReturnAttr>())
        FuncAttrs |= llvm::Attribute::NoReturn;
  
      if (TargetDecl->hasAttr<ReturnsTwiceAttr>())
        FuncAttrs |= llvm::Attribute::ReturnsTwice;
  
      // 'const' and 'pure' attribute functions are also nounwind.
      if (TargetDecl->hasAttr<ConstAttr>()) {
        FuncAttrs |= llvm::Attribute::ReadNone;
        FuncAttrs |= llvm::Attribute::NoUnwind;
      } else if (TargetDecl->hasAttr<PureAttr>()) {
        FuncAttrs |= llvm::Attribute::ReadOnly;
        FuncAttrs |= llvm::Attribute::NoUnwind;
      }
      if (TargetDecl->hasAttr<MallocAttr>())
        RetAttrs |= llvm::Attribute::NoAlias;
    }
  
    if (CodeGenOpts.OptimizeSize)
      FuncAttrs |= llvm::Attribute::OptimizeForSize;
    if (CodeGenOpts.DisableRedZone)
      FuncAttrs |= llvm::Attribute::NoRedZone;
    if (CodeGenOpts.NoImplicitFloat)
      FuncAttrs |= llvm::Attribute::NoImplicitFloat;
  
    QualType RetTy = FI.getReturnType();
    unsigned Index = 1;
    const ABIArgInfo &RetAI = FI.getReturnInfo();
    switch (RetAI.getKind()) {
    case ABIArgInfo::Extend:
     if (RetTy->hasSignedIntegerRepresentation())
       RetAttrs |= llvm::Attribute::SExt;
     else if (RetTy->hasUnsignedIntegerRepresentation())
       RetAttrs |= llvm::Attribute::ZExt;
      break;
    case ABIArgInfo::Direct:
    case ABIArgInfo::Ignore:
      break;
  
    case ABIArgInfo::Indirect:
      PAL.push_back(llvm::AttributeWithIndex::get(Index,
                                                  llvm::Attribute::StructRet));
      ++Index;
      // sret disables readnone and readonly
      FuncAttrs &= ~(llvm::Attribute::ReadOnly |
                     llvm::Attribute::ReadNone);
      break;
  
    case ABIArgInfo::Expand:
      llvm_unreachable("Invalid ABI kind for return argument");
    }
  
    if (RetAttrs)
      PAL.push_back(llvm::AttributeWithIndex::get(0, RetAttrs));
  
    // FIXME: RegParm should be reduced in case of global register variable.
    signed RegParm;
    if (FI.getHasRegParm())
      RegParm = FI.getRegParm();
    else
      RegParm = CodeGenOpts.NumRegisterParameters;
  
    unsigned PointerWidth = getContext().getTargetInfo().getPointerWidth(0);
    for (CGFunctionInfo::const_arg_iterator it = FI.arg_begin(),
           ie = FI.arg_end(); it != ie; ++it) {
      QualType ParamType = it->type;
      const ABIArgInfo &AI = it->info;
      llvm::Attributes Attrs;
  
      // 'restrict' -> 'noalias' is done in EmitFunctionProlog when we
      // have the corresponding parameter variable.  It doesn't make
      // sense to do it here because parameters are so messed up.
      switch (AI.getKind()) {
      case ABIArgInfo::Extend:
        if (ParamType->isSignedIntegerOrEnumerationType())
          Attrs |= llvm::Attribute::SExt;
        else if (ParamType->isUnsignedIntegerOrEnumerationType())
          Attrs |= llvm::Attribute::ZExt;
        // FALL THROUGH
      case ABIArgInfo::Direct:
        if (RegParm > 0 &&
            (ParamType->isIntegerType() || ParamType->isPointerType() ||
             ParamType->isReferenceType())) {
          RegParm -=
          (Context.getTypeSize(ParamType) + PointerWidth - 1) / PointerWidth;
          if (RegParm >= 0)
            Attrs |= llvm::Attribute::InReg;
        }
        // FIXME: handle sseregparm someday...
  
        // Increment Index if there is padding.
        Index += (AI.getPaddingType() != 0);
  
        if (llvm::StructType *STy =
              dyn_cast<llvm::StructType>(AI.getCoerceToType()))
          Index += STy->getNumElements()-1;  // 1 will be added below.
        break;
  
      case ABIArgInfo::Indirect:
        if (AI.getIndirectByVal())
          Attrs |= llvm::Attribute::ByVal;
  
        Attrs |=
          llvm::Attribute::constructAlignmentFromInt(AI.getIndirectAlign());
        // byval disables readnone and readonly.
        FuncAttrs &= ~(llvm::Attribute::ReadOnly |
                       llvm::Attribute::ReadNone);
        break;
  
      case ABIArgInfo::Ignore:
        // Skip increment, no matching LLVM parameter.
        continue;
  
      case ABIArgInfo::Expand: {
        SmallVector<llvm::Type*, 8> types;
        // FIXME: This is rather inefficient. Do we ever actually need to do
        // anything here? The result should be just reconstructed on the other
        // side, so extension should be a non-issue.
        getTypes().GetExpandedTypes(ParamType, types);
        Index += types.size();
        continue;
      }
      }
  
      if (Attrs)
        PAL.push_back(llvm::AttributeWithIndex::get(Index, Attrs));
      ++Index;
    }
    if (FuncAttrs)
      PAL.push_back(llvm::AttributeWithIndex::get(~0, FuncAttrs));
  }
  
  /// An argument came in as a promoted argument; demote it back to its
  /// declared type.
  static llvm::Value *emitArgumentDemotion(CodeGenFunction &CGF,
                                           const VarDecl *var,
                                           llvm::Value *value) {
    llvm::Type *varType = CGF.ConvertType(var->getType());
  
    // This can happen with promotions that actually don't change the
    // underlying type, like the enum promotions.
    if (value->getType() == varType) return value;
  
    assert((varType->isIntegerTy() || varType->isFloatingPointTy())
           && "unexpected promotion type");
  
    if (isa<llvm::IntegerType>(varType))
      return CGF.Builder.CreateTrunc(value, varType, "arg.unpromote");
  
    return CGF.Builder.CreateFPCast(value, varType, "arg.unpromote");
  }
  
  void CodeGenFunction::EmitFunctionProlog(const CGFunctionInfo &FI,
                                           llvm::Function *Fn,
                                           const FunctionArgList &Args) {
    // If this is an implicit-return-zero function, go ahead and
    // initialize the return value.  TODO: it might be nice to have
    // a more general mechanism for this that didn't require synthesized
    // return statements.
    if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(CurFuncDecl)) {
      if (FD->hasImplicitReturnZero()) {
        QualType RetTy = FD->getResultType().getUnqualifiedType();
        llvm::Type* LLVMTy = CGM.getTypes().ConvertType(RetTy);
        llvm::Constant* Zero = llvm::Constant::getNullValue(LLVMTy);
        Builder.CreateStore(Zero, ReturnValue);
      }
    }
  
    // FIXME: We no longer need the types from FunctionArgList; lift up and
    // simplify.
  
    // Emit allocs for param decls.  Give the LLVM Argument nodes names.
    llvm::Function::arg_iterator AI = Fn->arg_begin();
  
    // Name the struct return argument.
    if (CGM.ReturnTypeUsesSRet(FI)) {
      AI->setName("agg.result");
      AI->addAttr(llvm::Attribute::NoAlias);
      ++AI;
    }
  
    assert(FI.arg_size() == Args.size() &&
           "Mismatch between function signature & arguments.");
    unsigned ArgNo = 1;
    CGFunctionInfo::const_arg_iterator info_it = FI.arg_begin();
    for (FunctionArgList::const_iterator i = Args.begin(), e = Args.end(); 
         i != e; ++i, ++info_it, ++ArgNo) {
      const VarDecl *Arg = *i;
      QualType Ty = info_it->type;
      const ABIArgInfo &ArgI = info_it->info;
  
      bool isPromoted =
        isa<ParmVarDecl>(Arg) && cast<ParmVarDecl>(Arg)->isKNRPromoted();
  
      switch (ArgI.getKind()) {
      case ABIArgInfo::Indirect: {
        llvm::Value *V = AI;
  
        if (hasAggregateLLVMType(Ty)) {
          // Aggregates and complex variables are accessed by reference.  All we
          // need to do is realign the value, if requested
          if (ArgI.getIndirectRealign()) {
            llvm::Value *AlignedTemp = CreateMemTemp(Ty, "coerce");
  
            // Copy from the incoming argument pointer to the temporary with the
            // appropriate alignment.
            //
            // FIXME: We should have a common utility for generating an aggregate
            // copy.
            llvm::Type *I8PtrTy = Builder.getInt8PtrTy();
            CharUnits Size = getContext().getTypeSizeInChars(Ty);
            llvm::Value *Dst = Builder.CreateBitCast(AlignedTemp, I8PtrTy);
            llvm::Value *Src = Builder.CreateBitCast(V, I8PtrTy);
            Builder.CreateMemCpy(Dst,
                                 Src,
                                 llvm::ConstantInt::get(IntPtrTy, 
                                                        Size.getQuantity()),
                                 ArgI.getIndirectAlign(),
                                 false);
            V = AlignedTemp;
          }
        } else {
          // Load scalar value from indirect argument.
          CharUnits Alignment = getContext().getTypeAlignInChars(Ty);
          V = EmitLoadOfScalar(V, false, Alignment.getQuantity(), Ty);
  
          if (isPromoted)
            V = emitArgumentDemotion(*this, Arg, V);
        }
        EmitParmDecl(*Arg, V, ArgNo);
        break;
      }
  
      case ABIArgInfo::Extend:
      case ABIArgInfo::Direct: {
        // Skip the dummy padding argument.
        if (ArgI.getPaddingType())
          ++AI;
  
        // If we have the trivial case, handle it with no muss and fuss.
        if (!isa<llvm::StructType>(ArgI.getCoerceToType()) &&
            ArgI.getCoerceToType() == ConvertType(Ty) &&
            ArgI.getDirectOffset() == 0) {
          assert(AI != Fn->arg_end() && "Argument mismatch!");
          llvm::Value *V = AI;
  
          if (Arg->getType().isRestrictQualified())
            AI->addAttr(llvm::Attribute::NoAlias);
  
          // Ensure the argument is the correct type.
          if (V->getType() != ArgI.getCoerceToType())
            V = Builder.CreateBitCast(V, ArgI.getCoerceToType());
  
          if (isPromoted)
            V = emitArgumentDemotion(*this, Arg, V);
          
          EmitParmDecl(*Arg, V, ArgNo);
          break;
        }
  
        llvm::AllocaInst *Alloca = CreateMemTemp(Ty, Arg->getName());
  
        // The alignment we need to use is the max of the requested alignment for
        // the argument plus the alignment required by our access code below.
        unsigned AlignmentToUse =
          CGM.getTargetData().getABITypeAlignment(ArgI.getCoerceToType());
        AlignmentToUse = std::max(AlignmentToUse,
                          (unsigned)getContext().getDeclAlign(Arg).getQuantity());
  
        Alloca->setAlignment(AlignmentToUse);
        llvm::Value *V = Alloca;
        llvm::Value *Ptr = V;    // Pointer to store into.
  
        // If the value is offset in memory, apply the offset now.
        if (unsigned Offs = ArgI.getDirectOffset()) {
          Ptr = Builder.CreateBitCast(Ptr, Builder.getInt8PtrTy());
          Ptr = Builder.CreateConstGEP1_32(Ptr, Offs);
          Ptr = Builder.CreateBitCast(Ptr,
                            llvm::PointerType::getUnqual(ArgI.getCoerceToType()));
        }
  
        // If the coerce-to type is a first class aggregate, we flatten it and
        // pass the elements. Either way is semantically identical, but fast-isel
        // and the optimizer generally likes scalar values better than FCAs.
        llvm::StructType *STy = dyn_cast<llvm::StructType>(ArgI.getCoerceToType());
        if (STy && STy->getNumElements() > 1) {
          uint64_t SrcSize = CGM.getTargetData().getTypeAllocSize(STy);
          llvm::Type *DstTy =
            cast<llvm::PointerType>(Ptr->getType())->getElementType();
          uint64_t DstSize = CGM.getTargetData().getTypeAllocSize(DstTy);
  
          if (SrcSize <= DstSize) {
            Ptr = Builder.CreateBitCast(Ptr, llvm::PointerType::getUnqual(STy));
  
            for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
              assert(AI != Fn->arg_end() && "Argument mismatch!");
              AI->setName(Arg->getName() + ".coerce" + Twine(i));
              llvm::Value *EltPtr = Builder.CreateConstGEP2_32(Ptr, 0, i);
              Builder.CreateStore(AI++, EltPtr);
            }
          } else {
            llvm::AllocaInst *TempAlloca =
              CreateTempAlloca(ArgI.getCoerceToType(), "coerce");
            TempAlloca->setAlignment(AlignmentToUse);
            llvm::Value *TempV = TempAlloca;
  
            for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
              assert(AI != Fn->arg_end() && "Argument mismatch!");
              AI->setName(Arg->getName() + ".coerce" + Twine(i));
              llvm::Value *EltPtr = Builder.CreateConstGEP2_32(TempV, 0, i);
              Builder.CreateStore(AI++, EltPtr);
            }
  
            Builder.CreateMemCpy(Ptr, TempV, DstSize, AlignmentToUse);
          }
        } else {
          // Simple case, just do a coerced store of the argument into the alloca.
          assert(AI != Fn->arg_end() && "Argument mismatch!");
          AI->setName(Arg->getName() + ".coerce");
          CreateCoercedStore(AI++, Ptr, /*DestIsVolatile=*/false, *this);
        }
  
  
        // Match to what EmitParmDecl is expecting for this type.
        if (!CodeGenFunction::hasAggregateLLVMType(Ty)) {
          V = EmitLoadOfScalar(V, false, AlignmentToUse, Ty);
          if (isPromoted)
            V = emitArgumentDemotion(*this, Arg, V);
        }
        EmitParmDecl(*Arg, V, ArgNo);
        continue;  // Skip ++AI increment, already done.
      }
  
      case ABIArgInfo::Expand: {
        // If this structure was expanded into multiple arguments then
        // we need to create a temporary and reconstruct it from the
        // arguments.
        llvm::AllocaInst *Alloca = CreateMemTemp(Ty);
        CharUnits Align = getContext().getDeclAlign(Arg);
        Alloca->setAlignment(Align.getQuantity());
        LValue LV = MakeAddrLValue(Alloca, Ty, Align);
        llvm::Function::arg_iterator End = ExpandTypeFromArgs(Ty, LV, AI);
        EmitParmDecl(*Arg, Alloca, ArgNo);
  
        // Name the arguments used in expansion and increment AI.
        unsigned Index = 0;
        for (; AI != End; ++AI, ++Index)
          AI->setName(Arg->getName() + "." + Twine(Index));
        continue;
      }
  
      case ABIArgInfo::Ignore:
        // Initialize the local variable appropriately.
        if (hasAggregateLLVMType(Ty))
          EmitParmDecl(*Arg, CreateMemTemp(Ty), ArgNo);
        else
          EmitParmDecl(*Arg, llvm::UndefValue::get(ConvertType(Arg->getType())),
                       ArgNo);
  
        // Skip increment, no matching LLVM parameter.
        continue;
      }
  
      ++AI;
    }
    assert(AI == Fn->arg_end() && "Argument mismatch!");
  }
  
  static void eraseUnusedBitCasts(llvm::Instruction *insn) {
    while (insn->use_empty()) {
      llvm::BitCastInst *bitcast = dyn_cast<llvm::BitCastInst>(insn);
      if (!bitcast) return;
  
      // This is "safe" because we would have used a ConstantExpr otherwise.
      insn = cast<llvm::Instruction>(bitcast->getOperand(0));
      bitcast->eraseFromParent();
    }
  }
  
  /// Try to emit a fused autorelease of a return result.
  static llvm::Value *tryEmitFusedAutoreleaseOfResult(CodeGenFunction &CGF,
                                                      llvm::Value *result) {
    // We must be immediately followed the cast.
    llvm::BasicBlock *BB = CGF.Builder.GetInsertBlock();
    if (BB->empty()) return 0;
    if (&BB->back() != result) return 0;
  
    llvm::Type *resultType = result->getType();
  
    // result is in a BasicBlock and is therefore an Instruction.
    llvm::Instruction *generator = cast<llvm::Instruction>(result);
  
    SmallVector<llvm::Instruction*,4> insnsToKill;
  
    // Look for:
    //  %generator = bitcast %type1* %generator2 to %type2*
    while (llvm::BitCastInst *bitcast = dyn_cast<llvm::BitCastInst>(generator)) {
      // We would have emitted this as a constant if the operand weren't
      // an Instruction.
      generator = cast<llvm::Instruction>(bitcast->getOperand(0));
  
      // Require the generator to be immediately followed by the cast.
      if (generator->getNextNode() != bitcast)
        return 0;
  
      insnsToKill.push_back(bitcast);
    }
  
    // Look for:
    //   %generator = call i8* @objc_retain(i8* %originalResult)
    // or
    //   %generator = call i8* @objc_retainAutoreleasedReturnValue(i8* %originalResult)
    llvm::CallInst *call = dyn_cast<llvm::CallInst>(generator);
    if (!call) return 0;
  
    bool doRetainAutorelease;
  
    if (call->getCalledValue() == CGF.CGM.getARCEntrypoints().objc_retain) {
      doRetainAutorelease = true;
    } else if (call->getCalledValue() == CGF.CGM.getARCEntrypoints()
                                            .objc_retainAutoreleasedReturnValue) {
      doRetainAutorelease = false;
  
      // Look for an inline asm immediately preceding the call and kill it, too.
      llvm::Instruction *prev = call->getPrevNode();
      if (llvm::CallInst *asmCall = dyn_cast_or_null<llvm::CallInst>(prev))
        if (asmCall->getCalledValue()
              == CGF.CGM.getARCEntrypoints().retainAutoreleasedReturnValueMarker)
          insnsToKill.push_back(prev);
    } else {
      return 0;
    }
  
    result = call->getArgOperand(0);
    insnsToKill.push_back(call);
  
    // Keep killing bitcasts, for sanity.  Note that we no longer care
    // about precise ordering as long as there's exactly one use.
    while (llvm::BitCastInst *bitcast = dyn_cast<llvm::BitCastInst>(result)) {
      if (!bitcast->hasOneUse()) break;
      insnsToKill.push_back(bitcast);
      result = bitcast->getOperand(0);
    }
  
    // Delete all the unnecessary instructions, from latest to earliest.
    for (SmallVectorImpl<llvm::Instruction*>::iterator
           i = insnsToKill.begin(), e = insnsToKill.end(); i != e; ++i)
      (*i)->eraseFromParent();
  
    // Do the fused retain/autorelease if we were asked to.
    if (doRetainAutorelease)
      result = CGF.EmitARCRetainAutoreleaseReturnValue(result);
  
    // Cast back to the result type.
    return CGF.Builder.CreateBitCast(result, resultType);
  }
  
  /// If this is a +1 of the value of an immutable 'self', remove it.
  static llvm::Value *tryRemoveRetainOfSelf(CodeGenFunction &CGF,
                                            llvm::Value *result) {
    // This is only applicable to a method with an immutable 'self'.
    const ObjCMethodDecl *method = dyn_cast<ObjCMethodDecl>(CGF.CurCodeDecl);
    if (!method) return 0;
    const VarDecl *self = method->getSelfDecl();
    if (!self->getType().isConstQualified()) return 0;
  
    // Look for a retain call.
    llvm::CallInst *retainCall =
      dyn_cast<llvm::CallInst>(result->stripPointerCasts());
    if (!retainCall ||
        retainCall->getCalledValue() != CGF.CGM.getARCEntrypoints().objc_retain)
      return 0;
  
    // Look for an ordinary load of 'self'.
    llvm::Value *retainedValue = retainCall->getArgOperand(0);
    llvm::LoadInst *load =
      dyn_cast<llvm::LoadInst>(retainedValue->stripPointerCasts());
    if (!load || load->isAtomic() || load->isVolatile() || 
        load->getPointerOperand() != CGF.GetAddrOfLocalVar(self))
      return 0;
  
    // Okay!  Burn it all down.  This relies for correctness on the
    // assumption that the retain is emitted as part of the return and
    // that thereafter everything is used "linearly".
    llvm::Type *resultType = result->getType();
    eraseUnusedBitCasts(cast<llvm::Instruction>(result));
    assert(retainCall->use_empty());
    retainCall->eraseFromParent();
    eraseUnusedBitCasts(cast<llvm::Instruction>(retainedValue));
  
    return CGF.Builder.CreateBitCast(load, resultType);
  }
  
  /// Emit an ARC autorelease of the result of a function.
  ///
  /// \return the value to actually return from the function
  static llvm::Value *emitAutoreleaseOfResult(CodeGenFunction &CGF,
                                              llvm::Value *result) {
    // If we're returning 'self', kill the initial retain.  This is a
    // heuristic attempt to "encourage correctness" in the really unfortunate
    // case where we have a return of self during a dealloc and we desperately
    // need to avoid the possible autorelease.
    if (llvm::Value *self = tryRemoveRetainOfSelf(CGF, result))
      return self;
  
    // At -O0, try to emit a fused retain/autorelease.
    if (CGF.shouldUseFusedARCCalls())
      if (llvm::Value *fused = tryEmitFusedAutoreleaseOfResult(CGF, result))
        return fused;
  
    return CGF.EmitARCAutoreleaseReturnValue(result);
  }
  
  /// Heuristically search for a dominating store to the return-value slot.
  static llvm::StoreInst *findDominatingStoreToReturnValue(CodeGenFunction &CGF) {
    // If there are multiple uses of the return-value slot, just check
    // for something immediately preceding the IP.  Sometimes this can
    // happen with how we generate implicit-returns; it can also happen
    // with noreturn cleanups.
    if (!CGF.ReturnValue->hasOneUse()) {
      llvm::BasicBlock *IP = CGF.Builder.GetInsertBlock();
      if (IP->empty()) return 0;
      llvm::StoreInst *store = dyn_cast<llvm::StoreInst>(&IP->back());
      if (!store) return 0;
      if (store->getPointerOperand() != CGF.ReturnValue) return 0;
      assert(!store->isAtomic() && !store->isVolatile()); // see below
      return store;
    }
  
    llvm::StoreInst *store =
      dyn_cast<llvm::StoreInst>(CGF.ReturnValue->use_back());
    if (!store) return 0;
  
    // These aren't actually possible for non-coerced returns, and we
    // only care about non-coerced returns on this code path.
    assert(!store->isAtomic() && !store->isVolatile());
  
    // Now do a first-and-dirty dominance check: just walk up the
    // single-predecessors chain from the current insertion point.
    llvm::BasicBlock *StoreBB = store->getParent();
    llvm::BasicBlock *IP = CGF.Builder.GetInsertBlock();
    while (IP != StoreBB) {
      if (!(IP = IP->getSinglePredecessor()))
        return 0;
    }
  
    // Okay, the store's basic block dominates the insertion point; we
    // can do our thing.
    return store;
  }
  
  void CodeGenFunction::EmitFunctionEpilog(const CGFunctionInfo &FI) {
    // Functions with no result always return void.
    if (ReturnValue == 0) {
      Builder.CreateRetVoid();
      return;
    }
  
    llvm::DebugLoc RetDbgLoc;
    llvm::Value *RV = 0;
    QualType RetTy = FI.getReturnType();
    const ABIArgInfo &RetAI = FI.getReturnInfo();
  
    switch (RetAI.getKind()) {
    case ABIArgInfo::Indirect: {
      unsigned Alignment = getContext().getTypeAlignInChars(RetTy).getQuantity();
      if (RetTy->isAnyComplexType()) {
        ComplexPairTy RT = LoadComplexFromAddr(ReturnValue, false);
        StoreComplexToAddr(RT, CurFn->arg_begin(), false);
      } else if (CodeGenFunction::hasAggregateLLVMType(RetTy)) {
        // Do nothing; aggregrates get evaluated directly into the destination.
      } else {
        EmitStoreOfScalar(Builder.CreateLoad(ReturnValue), CurFn->arg_begin(),
                          false, Alignment, RetTy);
      }
      break;
    }
  
    case ABIArgInfo::Extend:
    case ABIArgInfo::Direct:
      if (RetAI.getCoerceToType() == ConvertType(RetTy) &&
          RetAI.getDirectOffset() == 0) {
        // The internal return value temp always will have pointer-to-return-type
        // type, just do a load.
  
        // If there is a dominating store to ReturnValue, we can elide
        // the load, zap the store, and usually zap the alloca.
        if (llvm::StoreInst *SI = findDominatingStoreToReturnValue(*this)) {
          // Get the stored value and nuke the now-dead store.
          RetDbgLoc = SI->getDebugLoc();
          RV = SI->getValueOperand();
          SI->eraseFromParent();
  
          // If that was the only use of the return value, nuke it as well now.
          if (ReturnValue->use_empty() && isa<llvm::AllocaInst>(ReturnValue)) {
            cast<llvm::AllocaInst>(ReturnValue)->eraseFromParent();
            ReturnValue = 0;
          }
  
        // Otherwise, we have to do a simple load.
        } else {
          RV = Builder.CreateLoad(ReturnValue);
        }
      } else {
        llvm::Value *V = ReturnValue;
        // If the value is offset in memory, apply the offset now.
        if (unsigned Offs = RetAI.getDirectOffset()) {
          V = Builder.CreateBitCast(V, Builder.getInt8PtrTy());
          V = Builder.CreateConstGEP1_32(V, Offs);
          V = Builder.CreateBitCast(V,
                           llvm::PointerType::getUnqual(RetAI.getCoerceToType()));
        }
  
        RV = CreateCoercedLoad(V, RetAI.getCoerceToType(), *this);
      }
  
      // In ARC, end functions that return a retainable type with a call
      // to objc_autoreleaseReturnValue.
      if (AutoreleaseResult) {
        assert(getLangOpts().ObjCAutoRefCount &&
               !FI.isReturnsRetained() &&
               RetTy->isObjCRetainableType());
        RV = emitAutoreleaseOfResult(*this, RV);
      }
  
      break;
  
    case ABIArgInfo::Ignore:
      break;
  
    case ABIArgInfo::Expand:
      llvm_unreachable("Invalid ABI kind for return argument");
    }
  
    llvm::Instruction *Ret = RV ? Builder.CreateRet(RV) : Builder.CreateRetVoid();
    if (!RetDbgLoc.isUnknown())
      Ret->setDebugLoc(RetDbgLoc);
  }
  
  void CodeGenFunction::EmitDelegateCallArg(CallArgList &args,
                                            const VarDecl *param) {
    // StartFunction converted the ABI-lowered parameter(s) into a
    // local alloca.  We need to turn that into an r-value suitable
    // for EmitCall.
    llvm::Value *local = GetAddrOfLocalVar(param);
  
    QualType type = param->getType();
  
    // For the most part, we just need to load the alloca, except:
    // 1) aggregate r-values are actually pointers to temporaries, and
    // 2) references to aggregates are pointers directly to the aggregate.
    // I don't know why references to non-aggregates are different here.
    if (const ReferenceType *ref = type->getAs<ReferenceType>()) {
      if (hasAggregateLLVMType(ref->getPointeeType()))
        return args.add(RValue::getAggregate(local), type);
  
      // Locals which are references to scalars are represented
      // with allocas holding the pointer.
      return args.add(RValue::get(Builder.CreateLoad(local)), type);
    }
  
    if (type->isAnyComplexType()) {
      ComplexPairTy complex = LoadComplexFromAddr(local, /*volatile*/ false);
      return args.add(RValue::getComplex(complex), type);
    }
  
    if (hasAggregateLLVMType(type))
      return args.add(RValue::getAggregate(local), type);
  
    unsigned alignment = getContext().getDeclAlign(param).getQuantity();
    llvm::Value *value = EmitLoadOfScalar(local, false, alignment, type);
    return args.add(RValue::get(value), type);
  }
  
  static bool isProvablyNull(llvm::Value *addr) {
    return isa<llvm::ConstantPointerNull>(addr);
  }
  
  static bool isProvablyNonNull(llvm::Value *addr) {
    return isa<llvm::AllocaInst>(addr);
  }
  
  /// Emit the actual writing-back of a writeback.
  static void emitWriteback(CodeGenFunction &CGF,
                            const CallArgList::Writeback &writeback) {
    llvm::Value *srcAddr = writeback.Address;
    assert(!isProvablyNull(srcAddr) &&
           "shouldn't have writeback for provably null argument");
  
    llvm::BasicBlock *contBB = 0;
  
    // If the argument wasn't provably non-null, we need to null check
    // before doing the store.
    bool provablyNonNull = isProvablyNonNull(srcAddr);
    if (!provablyNonNull) {
      llvm::BasicBlock *writebackBB = CGF.createBasicBlock("icr.writeback");
      contBB = CGF.createBasicBlock("icr.done");
  
      llvm::Value *isNull = CGF.Builder.CreateIsNull(srcAddr, "icr.isnull");
      CGF.Builder.CreateCondBr(isNull, contBB, writebackBB);
      CGF.EmitBlock(writebackBB);
    }
  
    // Load the value to writeback.
    llvm::Value *value = CGF.Builder.CreateLoad(writeback.Temporary);
  
    // Cast it back, in case we're writing an id to a Foo* or something.
    value = CGF.Builder.CreateBitCast(value,
                 cast<llvm::PointerType>(srcAddr->getType())->getElementType(),
                              "icr.writeback-cast");
    
    // Perform the writeback.
    QualType srcAddrType = writeback.AddressType;
    CGF.EmitStoreThroughLValue(RValue::get(value),
                               CGF.MakeAddrLValue(srcAddr, srcAddrType));
  
    // Jump to the continuation block.
    if (!provablyNonNull)
      CGF.EmitBlock(contBB);
  }
  
  static void emitWritebacks(CodeGenFunction &CGF,
                             const CallArgList &args) {
    for (CallArgList::writeback_iterator
           i = args.writeback_begin(), e = args.writeback_end(); i != e; ++i)
      emitWriteback(CGF, *i);
  }
  
  /// Emit an argument that's being passed call-by-writeback.  That is,
  /// we are passing the address of 
  static void emitWritebackArg(CodeGenFunction &CGF, CallArgList &args,
                               const ObjCIndirectCopyRestoreExpr *CRE) {
    llvm::Value *srcAddr = CGF.EmitScalarExpr(CRE->getSubExpr());
  
    // The dest and src types don't necessarily match in LLVM terms
    // because of the crazy ObjC compatibility rules.
  
    llvm::PointerType *destType =
      cast<llvm::PointerType>(CGF.ConvertType(CRE->getType()));
  
    // If the address is a constant null, just pass the appropriate null.
    if (isProvablyNull(srcAddr)) {
      args.add(RValue::get(llvm::ConstantPointerNull::get(destType)),
               CRE->getType());
      return;
    }
  
    QualType srcAddrType =
      CRE->getSubExpr()->getType()->castAs<PointerType>()->getPointeeType();
  
    // Create the temporary.
    llvm::Value *temp = CGF.CreateTempAlloca(destType->getElementType(),
                                             "icr.temp");
  
    // Zero-initialize it if we're not doing a copy-initialization.
    bool shouldCopy = CRE->shouldCopy();
    if (!shouldCopy) {
      llvm::Value *null =
        llvm::ConstantPointerNull::get(
          cast<llvm::PointerType>(destType->getElementType()));
      CGF.Builder.CreateStore(null, temp);
    }
  
    llvm::BasicBlock *contBB = 0;
  
    // If the address is *not* known to be non-null, we need to switch.
    llvm::Value *finalArgument;
  
    bool provablyNonNull = isProvablyNonNull(srcAddr);
    if (provablyNonNull) {
      finalArgument = temp;
    } else {
      llvm::Value *isNull = CGF.Builder.CreateIsNull(srcAddr, "icr.isnull");
  
      finalArgument = CGF.Builder.CreateSelect(isNull, 
                                     llvm::ConstantPointerNull::get(destType),
                                               temp, "icr.argument");
  
      // If we need to copy, then the load has to be conditional, which
      // means we need control flow.
      if (shouldCopy) {
        contBB = CGF.createBasicBlock("icr.cont");
        llvm::BasicBlock *copyBB = CGF.createBasicBlock("icr.copy");
        CGF.Builder.CreateCondBr(isNull, contBB, copyBB);
        CGF.EmitBlock(copyBB);
      }
    }
  
    // Perform a copy if necessary.
    if (shouldCopy) {
      LValue srcLV = CGF.MakeAddrLValue(srcAddr, srcAddrType);
      RValue srcRV = CGF.EmitLoadOfLValue(srcLV);
      assert(srcRV.isScalar());
  
      llvm::Value *src = srcRV.getScalarVal();
      src = CGF.Builder.CreateBitCast(src, destType->getElementType(),
                                      "icr.cast");
  
      // Use an ordinary store, not a store-to-lvalue.
      CGF.Builder.CreateStore(src, temp);
    }
  
    // Finish the control flow if we needed it.
    if (shouldCopy && !provablyNonNull)
      CGF.EmitBlock(contBB);
  
    args.addWriteback(srcAddr, srcAddrType, temp);
    args.add(RValue::get(finalArgument), CRE->getType());
  }
  
  void CodeGenFunction::EmitCallArg(CallArgList &args, const Expr *E,
                                    QualType type) {
    if (const ObjCIndirectCopyRestoreExpr *CRE
          = dyn_cast<ObjCIndirectCopyRestoreExpr>(E)) {
      assert(getContext().getLangOpts().ObjCAutoRefCount);
      assert(getContext().hasSameType(E->getType(), type));
      return emitWritebackArg(*this, args, CRE);
    }
  
    assert(type->isReferenceType() == E->isGLValue() &&
           "reference binding to unmaterialized r-value!");
  
    if (E->isGLValue()) {
      assert(E->getObjectKind() == OK_Ordinary);
      return args.add(EmitReferenceBindingToExpr(E, /*InitializedDecl=*/0),
                      type);
    }
  
    if (hasAggregateLLVMType(type) && !E->getType()->isAnyComplexType() &&
        isa<ImplicitCastExpr>(E) &&
        cast<CastExpr>(E)->getCastKind() == CK_LValueToRValue) {
      LValue L = EmitLValue(cast<CastExpr>(E)->getSubExpr());
      assert(L.isSimple());
      args.add(L.asAggregateRValue(), type, /*NeedsCopy*/true);
      return;
    }
  
    args.add(EmitAnyExprToTemp(E), type);
  }
  
  // In ObjC ARC mode with no ObjC ARC exception safety, tell the ARC
  // optimizer it can aggressively ignore unwind edges.
  void
  CodeGenFunction::AddObjCARCExceptionMetadata(llvm::Instruction *Inst) {
    if (CGM.getCodeGenOpts().OptimizationLevel != 0 &&
        !CGM.getCodeGenOpts().ObjCAutoRefCountExceptions)
      Inst->setMetadata("clang.arc.no_objc_arc_exceptions",
                        CGM.getNoObjCARCExceptionsMetadata());
  }
  
  /// Emits a call or invoke instruction to the given function, depending
  /// on the current state of the EH stack.
  llvm::CallSite
  CodeGenFunction::EmitCallOrInvoke(llvm::Value *Callee,
                                    ArrayRef<llvm::Value *> Args,
                                    const Twine &Name) {
    llvm::BasicBlock *InvokeDest = getInvokeDest();
  
    llvm::Instruction *Inst;
    if (!InvokeDest)
      Inst = Builder.CreateCall(Callee, Args, Name);
    else {
      llvm::BasicBlock *ContBB = createBasicBlock("invoke.cont");
      Inst = Builder.CreateInvoke(Callee, ContBB, InvokeDest, Args, Name);
      EmitBlock(ContBB);
    }
  
    // In ObjC ARC mode with no ObjC ARC exception safety, tell the ARC
    // optimizer it can aggressively ignore unwind edges.
    if (CGM.getLangOpts().ObjCAutoRefCount)
      AddObjCARCExceptionMetadata(Inst);
  
    return Inst;
  }
  
  llvm::CallSite
  CodeGenFunction::EmitCallOrInvoke(llvm::Value *Callee,
                                    const Twine &Name) {
    return EmitCallOrInvoke(Callee, ArrayRef<llvm::Value *>(), Name);
  }
  
  static void checkArgMatches(llvm::Value *Elt, unsigned &ArgNo,
                              llvm::FunctionType *FTy) {
    if (ArgNo < FTy->getNumParams())
      assert(Elt->getType() == FTy->getParamType(ArgNo));
    else
      assert(FTy->isVarArg());
    ++ArgNo;
  }
  
  void CodeGenFunction::ExpandTypeToArgs(QualType Ty, RValue RV,
                                         SmallVector<llvm::Value*,16> &Args,
                                         llvm::FunctionType *IRFuncTy) {
    if (const ConstantArrayType *AT = getContext().getAsConstantArrayType(Ty)) {
      unsigned NumElts = AT->getSize().getZExtValue();
      QualType EltTy = AT->getElementType();
      llvm::Value *Addr = RV.getAggregateAddr();
      for (unsigned Elt = 0; Elt < NumElts; ++Elt) {
        llvm::Value *EltAddr = Builder.CreateConstGEP2_32(Addr, 0, Elt);
        LValue LV = MakeAddrLValue(EltAddr, EltTy);
        RValue EltRV;
        if (EltTy->isAnyComplexType())
          // FIXME: Volatile?
          EltRV = RValue::getComplex(LoadComplexFromAddr(LV.getAddress(), false));
        else if (CodeGenFunction::hasAggregateLLVMType(EltTy))
          EltRV = LV.asAggregateRValue();
        else
          EltRV = EmitLoadOfLValue(LV);
        ExpandTypeToArgs(EltTy, EltRV, Args, IRFuncTy);
      }
    } else if (const RecordType *RT = Ty->getAs<RecordType>()) {
      RecordDecl *RD = RT->getDecl();
      assert(RV.isAggregate() && "Unexpected rvalue during struct expansion");
      LValue LV = MakeAddrLValue(RV.getAggregateAddr(), Ty);
  
      if (RD->isUnion()) {
        const FieldDecl *LargestFD = 0;
        CharUnits UnionSize = CharUnits::Zero();
  
        for (RecordDecl::field_iterator i = RD->field_begin(), e = RD->field_end();
             i != e; ++i) {
          const FieldDecl *FD = *i;
          assert(!FD->isBitField() &&
                 "Cannot expand structure with bit-field members.");
          CharUnits FieldSize = getContext().getTypeSizeInChars(FD->getType());
          if (UnionSize < FieldSize) {
            UnionSize = FieldSize;
            LargestFD = FD;
          }
        }
        if (LargestFD) {
          RValue FldRV = EmitRValueForField(LV, LargestFD);
          ExpandTypeToArgs(LargestFD->getType(), FldRV, Args, IRFuncTy);
        }
      } else {
        for (RecordDecl::field_iterator i = RD->field_begin(), e = RD->field_end();
             i != e; ++i) {
          FieldDecl *FD = *i;
  
          RValue FldRV = EmitRValueForField(LV, FD);
          ExpandTypeToArgs(FD->getType(), FldRV, Args, IRFuncTy);
        }
      }
    } else if (Ty->isAnyComplexType()) {
      ComplexPairTy CV = RV.getComplexVal();
      Args.push_back(CV.first);
      Args.push_back(CV.second);
    } else {
      assert(RV.isScalar() &&
             "Unexpected non-scalar rvalue during struct expansion.");
  
      // Insert a bitcast as needed.
      llvm::Value *V = RV.getScalarVal();
      if (Args.size() < IRFuncTy->getNumParams() &&
          V->getType() != IRFuncTy->getParamType(Args.size()))
        V = Builder.CreateBitCast(V, IRFuncTy->getParamType(Args.size()));
  
      Args.push_back(V);
    }
  }
  
  
  RValue CodeGenFunction::EmitCall(const CGFunctionInfo &CallInfo,
                                   llvm::Value *Callee,
                                   ReturnValueSlot ReturnValue,
                                   const CallArgList &CallArgs,
                                   const Decl *TargetDecl,
                                   llvm::Instruction **callOrInvoke) {
    // FIXME: We no longer need the types from CallArgs; lift up and simplify.
    SmallVector<llvm::Value*, 16> Args;
  
    // Handle struct-return functions by passing a pointer to the
    // location that we would like to return into.
    QualType RetTy = CallInfo.getReturnType();
    const ABIArgInfo &RetAI = CallInfo.getReturnInfo();
  
    // IRArgNo - Keep track of the argument number in the callee we're looking at.
    unsigned IRArgNo = 0;
    llvm::FunctionType *IRFuncTy =
      cast<llvm::FunctionType>(
                    cast<llvm::PointerType>(Callee->getType())->getElementType());
  
    // If the call returns a temporary with struct return, create a temporary
    // alloca to hold the result, unless one is given to us.
    if (CGM.ReturnTypeUsesSRet(CallInfo)) {
      llvm::Value *Value = ReturnValue.getValue();
      if (!Value)
        Value = CreateMemTemp(RetTy);
      Args.push_back(Value);
      checkArgMatches(Value, IRArgNo, IRFuncTy);
    }
  
    assert(CallInfo.arg_size() == CallArgs.size() &&
           "Mismatch between function signature & arguments.");
    CGFunctionInfo::const_arg_iterator info_it = CallInfo.arg_begin();
    for (CallArgList::const_iterator I = CallArgs.begin(), E = CallArgs.end();
         I != E; ++I, ++info_it) {
      const ABIArgInfo &ArgInfo = info_it->info;
      RValue RV = I->RV;
  
      unsigned TypeAlign =
        getContext().getTypeAlignInChars(I->Ty).getQuantity();
      switch (ArgInfo.getKind()) {
      case ABIArgInfo::Indirect: {
        if (RV.isScalar() || RV.isComplex()) {
          // Make a temporary alloca to pass the argument.
          llvm::AllocaInst *AI = CreateMemTemp(I->Ty);
          if (ArgInfo.getIndirectAlign() > AI->getAlignment())
            AI->setAlignment(ArgInfo.getIndirectAlign());
          Args.push_back(AI);
          
          if (RV.isScalar())
            EmitStoreOfScalar(RV.getScalarVal(), Args.back(), false,
                              TypeAlign, I->Ty);
          else
            StoreComplexToAddr(RV.getComplexVal(), Args.back(), false);
          
          // Validate argument match.
          checkArgMatches(AI, IRArgNo, IRFuncTy);
        } else {
          // We want to avoid creating an unnecessary temporary+copy here;
          // however, we need one in two cases:
          // 1. If the argument is not byval, and we are required to copy the
          //    source.  (This case doesn't occur on any common architecture.)
          // 2. If the argument is byval, RV is not sufficiently aligned, and
          //    we cannot force it to be sufficiently aligned.
          llvm::Value *Addr = RV.getAggregateAddr();
          unsigned Align = ArgInfo.getIndirectAlign();
          const llvm::TargetData *TD = &CGM.getTargetData();
          if ((!ArgInfo.getIndirectByVal() && I->NeedsCopy) ||
              (ArgInfo.getIndirectByVal() && TypeAlign < Align &&
               llvm::getOrEnforceKnownAlignment(Addr, Align, TD) < Align)) {
            // Create an aligned temporary, and copy to it.
            llvm::AllocaInst *AI = CreateMemTemp(I->Ty);
            if (Align > AI->getAlignment())
              AI->setAlignment(Align);
            Args.push_back(AI);
            EmitAggregateCopy(AI, Addr, I->Ty, RV.isVolatileQualified());
                
            // Validate argument match.
            checkArgMatches(AI, IRArgNo, IRFuncTy);
          } else {
            // Skip the extra memcpy call.
            Args.push_back(Addr);
            
            // Validate argument match.
            checkArgMatches(Addr, IRArgNo, IRFuncTy);
          }
        }
        break;
      }
  
      case ABIArgInfo::Ignore:
        break;
  
      case ABIArgInfo::Extend:
      case ABIArgInfo::Direct: {
        // Insert a padding argument to ensure proper alignment.
        if (llvm::Type *PaddingType = ArgInfo.getPaddingType()) {
          Args.push_back(llvm::UndefValue::get(PaddingType));
          ++IRArgNo;
        }
  
        if (!isa<llvm::StructType>(ArgInfo.getCoerceToType()) &&
            ArgInfo.getCoerceToType() == ConvertType(info_it->type) &&
            ArgInfo.getDirectOffset() == 0) {
          llvm::Value *V;
          if (RV.isScalar())
            V = RV.getScalarVal();
          else
            V = Builder.CreateLoad(RV.getAggregateAddr());
          
          // If the argument doesn't match, perform a bitcast to coerce it.  This
          // can happen due to trivial type mismatches.
          if (IRArgNo < IRFuncTy->getNumParams() &&
              V->getType() != IRFuncTy->getParamType(IRArgNo))
            V = Builder.CreateBitCast(V, IRFuncTy->getParamType(IRArgNo));
          Args.push_back(V);
          
          checkArgMatches(V, IRArgNo, IRFuncTy);
          break;
        }
  
        // FIXME: Avoid the conversion through memory if possible.
        llvm::Value *SrcPtr;
        if (RV.isScalar()) {
          SrcPtr = CreateMemTemp(I->Ty, "coerce");
          EmitStoreOfScalar(RV.getScalarVal(), SrcPtr, false, TypeAlign, I->Ty);
        } else if (RV.isComplex()) {
          SrcPtr = CreateMemTemp(I->Ty, "coerce");
          StoreComplexToAddr(RV.getComplexVal(), SrcPtr, false);
        } else
          SrcPtr = RV.getAggregateAddr();
  
        // If the value is offset in memory, apply the offset now.
        if (unsigned Offs = ArgInfo.getDirectOffset()) {
          SrcPtr = Builder.CreateBitCast(SrcPtr, Builder.getInt8PtrTy());
          SrcPtr = Builder.CreateConstGEP1_32(SrcPtr, Offs);
          SrcPtr = Builder.CreateBitCast(SrcPtr,
                         llvm::PointerType::getUnqual(ArgInfo.getCoerceToType()));
  
        }
  
        // If the coerce-to type is a first class aggregate, we flatten it and
        // pass the elements. Either way is semantically identical, but fast-isel
        // and the optimizer generally likes scalar values better than FCAs.
        if (llvm::StructType *STy =
              dyn_cast<llvm::StructType>(ArgInfo.getCoerceToType())) {
          SrcPtr = Builder.CreateBitCast(SrcPtr,
                                         llvm::PointerType::getUnqual(STy));
          for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
            llvm::Value *EltPtr = Builder.CreateConstGEP2_32(SrcPtr, 0, i);
            llvm::LoadInst *LI = Builder.CreateLoad(EltPtr);
            // We don't know what we're loading from.
            LI->setAlignment(1);
            Args.push_back(LI);
            
            // Validate argument match.
            checkArgMatches(LI, IRArgNo, IRFuncTy);
          }
        } else {
          // In the simple case, just pass the coerced loaded value.
          Args.push_back(CreateCoercedLoad(SrcPtr, ArgInfo.getCoerceToType(),
                                           *this));
          
          // Validate argument match.
          checkArgMatches(Args.back(), IRArgNo, IRFuncTy);
        }
  
        break;
      }
  
      case ABIArgInfo::Expand:
        ExpandTypeToArgs(I->Ty, RV, Args, IRFuncTy);
        IRArgNo = Args.size();
        break;
      }
    }
  
    // If the callee is a bitcast of a function to a varargs pointer to function
    // type, check to see if we can remove the bitcast.  This handles some cases
    // with unprototyped functions.
    if (llvm::ConstantExpr *CE = dyn_cast<llvm::ConstantExpr>(Callee))
      if (llvm::Function *CalleeF = dyn_cast<llvm::Function>(CE->getOperand(0))) {
        llvm::PointerType *CurPT=cast<llvm::PointerType>(Callee->getType());
        llvm::FunctionType *CurFT =
          cast<llvm::FunctionType>(CurPT->getElementType());
        llvm::FunctionType *ActualFT = CalleeF->getFunctionType();
  
        if (CE->getOpcode() == llvm::Instruction::BitCast &&
            ActualFT->getReturnType() == CurFT->getReturnType() &&
            ActualFT->getNumParams() == CurFT->getNumParams() &&
            ActualFT->getNumParams() == Args.size() &&
            (CurFT->isVarArg() || !ActualFT->isVarArg())) {
          bool ArgsMatch = true;
          for (unsigned i = 0, e = ActualFT->getNumParams(); i != e; ++i)
            if (ActualFT->getParamType(i) != CurFT->getParamType(i)) {
              ArgsMatch = false;
              break;
            }
  
          // Strip the cast if we can get away with it.  This is a nice cleanup,
          // but also allows us to inline the function at -O0 if it is marked
          // always_inline.
          if (ArgsMatch)
            Callee = CalleeF;
        }
      }
  
    unsigned CallingConv;
    CodeGen::AttributeListType AttributeList;
    CGM.ConstructAttributeList(CallInfo, TargetDecl, AttributeList, CallingConv);
    llvm::AttrListPtr Attrs = llvm::AttrListPtr::get(AttributeList.begin(),
                                                     AttributeList.end());
  
    llvm::BasicBlock *InvokeDest = 0;
    if (!(Attrs.getFnAttributes() & llvm::Attribute::NoUnwind))
      InvokeDest = getInvokeDest();
  
    llvm::CallSite CS;
    if (!InvokeDest) {
      CS = Builder.CreateCall(Callee, Args);
    } else {
      llvm::BasicBlock *Cont = createBasicBlock("invoke.cont");
      CS = Builder.CreateInvoke(Callee, Cont, InvokeDest, Args);
      EmitBlock(Cont);
    }
    if (callOrInvoke)
      *callOrInvoke = CS.getInstruction();
  
    CS.setAttributes(Attrs);
    CS.setCallingConv(static_cast<llvm::CallingConv::ID>(CallingConv));
  
    // In ObjC ARC mode with no ObjC ARC exception safety, tell the ARC
    // optimizer it can aggressively ignore unwind edges.
    if (CGM.getLangOpts().ObjCAutoRefCount)
      AddObjCARCExceptionMetadata(CS.getInstruction());
  
    // If the call doesn't return, finish the basic block and clear the
    // insertion point; this allows the rest of IRgen to discard
    // unreachable code.
    if (CS.doesNotReturn()) {
      Builder.CreateUnreachable();
      Builder.ClearInsertionPoint();
  
      // FIXME: For now, emit a dummy basic block because expr emitters in
      // generally are not ready to handle emitting expressions at unreachable
      // points.
      EnsureInsertPoint();
  
      // Return a reasonable RValue.
      return GetUndefRValue(RetTy);
    }
  
    llvm::Instruction *CI = CS.getInstruction();
    if (Builder.isNamePreserving() && !CI->getType()->isVoidTy())
      CI->setName("call");
  
    // Emit any writebacks immediately.  Arguably this should happen
    // after any return-value munging.
    if (CallArgs.hasWritebacks())
      emitWritebacks(*this, CallArgs);
  
    switch (RetAI.getKind()) {
    case ABIArgInfo::Indirect: {
      unsigned Alignment = getContext().getTypeAlignInChars(RetTy).getQuantity();
      if (RetTy->isAnyComplexType())
        return RValue::getComplex(LoadComplexFromAddr(Args[0], false));
      if (CodeGenFunction::hasAggregateLLVMType(RetTy))
        return RValue::getAggregate(Args[0]);
      return RValue::get(EmitLoadOfScalar(Args[0], false, Alignment, RetTy));
    }
  
    case ABIArgInfo::Ignore:
      // If we are ignoring an argument that had a result, make sure to
      // construct the appropriate return value for our caller.
      return GetUndefRValue(RetTy);
  
    case ABIArgInfo::Extend:
    case ABIArgInfo::Direct: {
      llvm::Type *RetIRTy = ConvertType(RetTy);
      if (RetAI.getCoerceToType() == RetIRTy && RetAI.getDirectOffset() == 0) {
        if (RetTy->isAnyComplexType()) {
          llvm::Value *Real = Builder.CreateExtractValue(CI, 0);
          llvm::Value *Imag = Builder.CreateExtractValue(CI, 1);
          return RValue::getComplex(std::make_pair(Real, Imag));
        }
        if (CodeGenFunction::hasAggregateLLVMType(RetTy)) {
          llvm::Value *DestPtr = ReturnValue.getValue();
          bool DestIsVolatile = ReturnValue.isVolatile();
  
          if (!DestPtr) {
            DestPtr = CreateMemTemp(RetTy, "agg.tmp");
            DestIsVolatile = false;
          }
          BuildAggStore(*this, CI, DestPtr, DestIsVolatile, false);
          return RValue::getAggregate(DestPtr);
        }
        
        // If the argument doesn't match, perform a bitcast to coerce it.  This
        // can happen due to trivial type mismatches.
        llvm::Value *V = CI;
        if (V->getType() != RetIRTy)
          V = Builder.CreateBitCast(V, RetIRTy);
        return RValue::get(V);
      }
  
      llvm::Value *DestPtr = ReturnValue.getValue();
      bool DestIsVolatile = ReturnValue.isVolatile();
  
      if (!DestPtr) {
        DestPtr = CreateMemTemp(RetTy, "coerce");
        DestIsVolatile = false;
      }
  
      // If the value is offset in memory, apply the offset now.
      llvm::Value *StorePtr = DestPtr;
      if (unsigned Offs = RetAI.getDirectOffset()) {
        StorePtr = Builder.CreateBitCast(StorePtr, Builder.getInt8PtrTy());
        StorePtr = Builder.CreateConstGEP1_32(StorePtr, Offs);
        StorePtr = Builder.CreateBitCast(StorePtr,
                           llvm::PointerType::getUnqual(RetAI.getCoerceToType()));
      }
      CreateCoercedStore(CI, StorePtr, DestIsVolatile, *this);
  
      unsigned Alignment = getContext().getTypeAlignInChars(RetTy).getQuantity();
      if (RetTy->isAnyComplexType())
        return RValue::getComplex(LoadComplexFromAddr(DestPtr, false));
      if (CodeGenFunction::hasAggregateLLVMType(RetTy))
        return RValue::getAggregate(DestPtr);
      return RValue::get(EmitLoadOfScalar(DestPtr, false, Alignment, RetTy));
    }
  
    case ABIArgInfo::Expand:
      llvm_unreachable("Invalid ABI kind for return argument");
    }
  
    llvm_unreachable("Unhandled ABIArgInfo::Kind");
  }
  
  /* VarArg handling */
  
  llvm::Value *CodeGenFunction::EmitVAArg(llvm::Value *VAListAddr, QualType Ty) {
    return CGM.getTypes().getABIInfo().EmitVAArg(VAListAddr, Ty, *this);
  }
  