/* APPLE LOCAL begin LLVM (ENTIRE FILE!)  */
/* High-level LLVM backend interface 
Copyright (C) 2005, 2006, 2007 Free Software Foundation, Inc.
Contributed by Chris Lattner (sabre@nondot.org)

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 2, or (at your option) any later
version.

GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
for more details.

You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING.  If not, write to the Free
Software Foundation, 59 Temple Place - Suite 330, Boston, MA
02111-1307, USA.  */

//===----------------------------------------------------------------------===//
// This is the code that converts GCC AST nodes into LLVM code.
//===----------------------------------------------------------------------===//

#include "llvm/ValueSymbolTable.h"
#include "llvm-abi.h"
#include "llvm-internal.h"
#include "llvm-debug.h"
#include "llvm/CallingConv.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/InlineAsm.h"
#include "llvm/Instructions.h"
#include "llvm/Module.h"
#include "llvm/ParameterAttributes.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Target/TargetAsmInfo.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/DenseMap.h"
#include <iostream>

extern "C" {
#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "tm_p.h"
#include "tree.h"
#include "c-tree.h"  // FIXME: eliminate.
#include "tree-iterator.h"
#include "output.h"
#include "diagnostic.h"
#include "real.h"
#include "langhooks.h"
#include "function.h"
#include "toplev.h"
#include "flags.h"
#include "target.h"
#include "hard-reg-set.h"
#include "except.h"
#include "rtl.h"
extern bool tree_could_throw_p(tree);  // tree-flow.h uses non-C++ C constructs.
extern int get_pointer_alignment (tree exp, unsigned int max_align);
extern enum machine_mode reg_raw_mode[FIRST_PSEUDO_REGISTER];
}

#define ITANIUM_STYLE_EXCEPTIONS

//===----------------------------------------------------------------------===//
//                   Matching LLVM Values with GCC DECL trees
//===----------------------------------------------------------------------===//
//
// LLVMValues is a vector of LLVM Values. GCC tree nodes keep track of LLVM 
// Values using this vector's index. It is easier to save and restore the index 
// than the LLVM Value pointer while usig PCH. 

// Collection of LLVM Values

static std::vector<Value *> LLVMValues;
typedef DenseMap<Value *, unsigned> LLVMValuesMapTy;
static LLVMValuesMapTy LLVMValuesMap;

// Remember the LLVM value for GCC tree node.
void llvm_set_decl(tree Tr, Value *V) {

  // If there is not any value then do not add new LLVMValues entry.
  // However clear Tr index if it is non zero.
  if (!V) {
    if (GET_DECL_LLVM_INDEX(Tr))
      SET_DECL_LLVM_INDEX(Tr, 0);
    return;
  }

  unsigned &ValueSlot = LLVMValuesMap[V];
  if (ValueSlot) {
    // Already in map
    SET_DECL_LLVM_INDEX(Tr, ValueSlot);
    return;
  }

  unsigned Index = LLVMValues.size() + 1;
  LLVMValues.push_back(V);
  SET_DECL_LLVM_INDEX(Tr, Index);
  LLVMValuesMap[V] = Index;
}

// Return TRUE if there is a LLVM Value associate with GCC tree node.
bool llvm_set_decl_p(tree Tr) {
  unsigned Index = GET_DECL_LLVM_INDEX(Tr);
  if (Index == 0)
    return false;

  if (LLVMValues[Index - 1])
    return true;

  return false;
}

// Get LLVM Value for the GCC tree node based on LLVMValues vector index.
// If there is not any value associated then use make_decl_llvm() to 
// make LLVM value. When GCC tree node is initialized, it has 0 as the 
// index value. This is why all recorded indices are offset by 1.
Value *llvm_get_decl(tree Tr) {

  unsigned Index = GET_DECL_LLVM_INDEX(Tr);
  if (Index == 0) {
    make_decl_llvm(Tr);
    Index = GET_DECL_LLVM_INDEX(Tr);
    
    // If there was an error, we may have disabled creating LLVM values.
    if (Index == 0) return 0;
  }
  assert ((Index - 1) < LLVMValues.size() && "Invalid LLVM value index");
  assert (LLVMValues[Index - 1] && "Trying to use deleted LLVM value!");

  return LLVMValues[Index - 1];
}

/// changeLLVMValue - If Old exists in the LLVMValues map, rewrite it to New.
/// At this point we know that New is not in the map.
void changeLLVMValue(Value *Old, Value *New) {
  assert(!LLVMValuesMap.count(New) && "New cannot be in the map!");
  
  // Find Old in the table.
  LLVMValuesMapTy::iterator I = LLVMValuesMap.find(Old);
  if (I == LLVMValuesMap.end()) return;
  
  unsigned Idx = I->second-1;
  assert(Idx < LLVMValues.size() && "Out of range index!");
  assert(LLVMValues[Idx] == Old && "Inconsistent LLVMValues mapping!");
  
  LLVMValues[Idx] = New;
  
  // Remove the old value from the value map.
  LLVMValuesMap.erase(I);
  
  // Insert the new value into the value map.  We know that it can't already
  // exist in the mapping.
  if (New)
    LLVMValuesMap[New] = Idx+1;
}

// Read LLVM Types string table
void readLLVMValues() {

  GlobalValue *V = TheModule->getNamedGlobal("llvm.pch.values");
  if (!V)
    return;

  GlobalVariable *GV = cast<GlobalVariable>(V);
  ConstantStruct *ValuesFromPCH = cast<ConstantStruct>(GV->getOperand(0));

  for (unsigned i = 0; i < ValuesFromPCH->getNumOperands(); ++i) {
    Value *Va = ValuesFromPCH->getOperand(i);

    if (!Va) {
      // If V is empty then nsert NULL to represent empty entries.
      LLVMValues.push_back(Va);
      continue;
    }
    if (ConstantArray *CA = dyn_cast<ConstantArray>(Va)) {
      std::string Str = CA->getAsString();
      Va = TheModule->getValueSymbolTable().lookup(Str);
    } 
    assert (Va != NULL && "Invalid Value in LLVMValues string table");
    LLVMValues.push_back(Va);
  }

  // Now, llvm.pch.values is not required so remove it from the symbol table.
  GV->eraseFromParent();
}

// GCC tree's uses LLVMValues vector's index to reach LLVM Values.
// Create a string table to hold these LLVM Values' names. This string
// table will be used to recreate LTypes vector after loading PCH.
void writeLLVMValues() {
  
  if (LLVMValues.empty()) 
    return;

  std::vector<Constant *> ValuesForPCH;

  for (std::vector<Value *>::iterator I = LLVMValues.begin(),
         E = LLVMValues.end(); I != E; ++I)  {
    if (Constant *C = dyn_cast_or_null<Constant>(*I))
      ValuesForPCH.push_back(C);
    else
      // Non constant values, e.g. arguments, are not at global scope.
      // When PCH is read, only global scope values are used.
      ValuesForPCH.push_back(Constant::getNullValue(Type::Int32Ty));
  }

  // Create string table.
  Constant *LLVMValuesTable = ConstantStruct::get(ValuesForPCH, false);

  // Create variable to hold this string table.
  new GlobalVariable(LLVMValuesTable->getType(), true,
                     GlobalValue::ExternalLinkage, 
                     LLVMValuesTable,
                     "llvm.pch.values", TheModule);
}

/// eraseLocalLLVMValues - drop all non-global values from the LLVM values map.
void eraseLocalLLVMValues() {
  // Try to reduce the size of LLVMValues by removing local values from the end.
  std::vector<Value *>::reverse_iterator I, E;

  for (I = LLVMValues.rbegin(), E = LLVMValues.rend(); I != E; ++I) {
    if (Value *V = *I) {
      if (isa<Constant>(V))
        break;
      else
        LLVMValuesMap.erase(V);
    }
  }

  LLVMValues.erase(I.base(), LLVMValues.end()); // Drop erased values

  // Iterate over LLVMValuesMap since it may be much smaller than LLVMValues.
  for (LLVMValuesMapTy::iterator I = LLVMValuesMap.begin(),
       E = LLVMValuesMap.end(); I != E; ++I) {
    assert(I->first && "Values map contains NULL!");
    if (!isa<Constant>(I->first)) {
      unsigned Index = I->second - 1;
      assert(Index < LLVMValues.size() && LLVMValues[Index] == I->first &&
             "Inconsistent value map!");
      LLVMValues[Index] = NULL;
      LLVMValuesMap.erase(I);
    }
  }
}

/// isGCC_SSA_Temporary - Return true if this is an SSA temporary that we can
/// directly compile into an LLVM temporary.  This saves us from creating an
/// alloca and creating loads/stores of that alloca (a compile-time win).  We
/// can only do this if the value is a first class llvm value and if it's a 
/// "gimple_formal_tmp_var".
static bool isGCC_SSA_Temporary(tree decl) {
  return TREE_CODE(decl) == VAR_DECL &&
         DECL_GIMPLE_FORMAL_TEMP_P(decl) && !TREE_ADDRESSABLE(decl) &&
         !isAggregateTreeType(TREE_TYPE(decl));
}

/// isStructWithVarSizeArrayAtEnd - Return true if this StructType contains a
/// zero sized array as its last element.  This typically happens due to C
/// constructs like:  struct X { int A; char B[]; };
static bool isStructWithVarSizeArrayAtEnd(const Type *Ty) {
  const StructType *STy = dyn_cast<StructType>(Ty);
  if (STy == 0) return false;
  assert(STy->getNumElements() && "empty struct?");
  const Type *LastElTy = STy->getElementType(STy->getNumElements()-1);
  return isa<ArrayType>(LastElTy) && 
         cast<ArrayType>(LastElTy)->getNumElements() == 0;
}

/// getINTEGER_CSTVal - Return the specified INTEGER_CST value as a uint64_t.
///
static uint64_t getINTEGER_CSTVal(tree exp) {
  unsigned HOST_WIDE_INT HI = (unsigned HOST_WIDE_INT)TREE_INT_CST_HIGH(exp);
  unsigned HOST_WIDE_INT LO = (unsigned HOST_WIDE_INT)TREE_INT_CST_LOW(exp);
  if (HOST_BITS_PER_WIDE_INT == 64) {
    return (uint64_t)LO;
  } else {
    assert(HOST_BITS_PER_WIDE_INT == 32 &&
           "Only 32- and 64-bit hosts supported!");
    return ((uint64_t)HI << 32) | (uint64_t)LO;
  }
}

/// isInt64 - Return true if t is an INTEGER_CST that fits in a 64 bit integer.
/// If Unsigned is false, returns whether it fits in a int64_t.  If Unsigned is
/// true, returns whether the value is non-negative and fits in a uint64_t.
/// Always returns false for overflowed constants.
bool isInt64(tree_node *t, bool Unsigned) {
  if (HOST_BITS_PER_WIDE_INT == 64)
    return host_integerp(t, Unsigned);
  else {
    assert(HOST_BITS_PER_WIDE_INT == 32 &&
           "Only 32- and 64-bit hosts supported!");
    return
      (TREE_CODE (t) == INTEGER_CST && !TREE_OVERFLOW (t))
      && ((TYPE_UNSIGNED(TREE_TYPE(t)) == Unsigned) ||
          // If the constant is signed and we want an unsigned result, check
          // that the value is non-negative.  If the constant is unsigned and
          // we want a signed result, check it fits in 63 bits.
          (HOST_WIDE_INT)TREE_INT_CST_HIGH(t) >= 0);
  }
}

/// getInt64 - Extract the value of an INTEGER_CST as a 64 bit integer.  If
/// Unsigned is false, the value must fit in a int64_t.  If Unsigned is true,
/// the value must be non-negative and fit in a uint64_t.  Must not be used on
/// overflowed constants.  These conditions can be checked by calling isInt64.
uint64_t getInt64(tree_node *t, bool Unsigned) {
  assert(isInt64(t, Unsigned) && "invalid constant!");
  return getINTEGER_CSTVal(t);
}

//===----------------------------------------------------------------------===//
//                         ... High-Level Methods ...
//===----------------------------------------------------------------------===//

/// TheTreeToLLVM - Keep track of the current function being compiled.  This is
/// only to support the address of labels extension.
static TreeToLLVM *TheTreeToLLVM = 0;

const TargetData &getTargetData() {
  return *TheTarget->getTargetData();
}

TreeToLLVM::TreeToLLVM(tree fndecl) : TD(getTargetData()) {
  FnDecl = fndecl;
  Fn = 0;
  ReturnBB = UnwindBB = 0;
  
  if (TheDebugInfo) {
    expanded_location Location = expand_location(DECL_SOURCE_LOCATION (fndecl));
     
    if (Location.file) {
      TheDebugInfo->setLocationFile(Location.file);
      TheDebugInfo->setLocationLine(Location.line);
    } else {
      TheDebugInfo->setLocationFile("<unknown file>");
      TheDebugInfo->setLocationLine(0);
    }
  }

  AllocaInsertionPoint = 0;

  UsedSRetBuffer = false;

  CleanupFilter = NULL_TREE;
  ExceptionValue = 0;
  ExceptionSelectorValue = 0;
  FuncEHException = 0;
  FuncEHSelector = 0;
  FuncEHGetTypeID = 0;
  FuncCPPPersonality = 0;
  FuncUnwindResume = 0; 
  
  NumAddressTakenBlocks = 0;
  IndirectGotoBlock = 0;
  CurrentEHScopes.reserve(16);
  
  assert(TheTreeToLLVM == 0 && "Reentering function creation?");
  TheTreeToLLVM = this;
}

TreeToLLVM::~TreeToLLVM() {
  TheTreeToLLVM = 0;
}

namespace {
  /// FunctionPrologArgumentConversion - This helper class is driven by the ABI
  /// definition for this target to figure out how to retrieve arguments from
  /// the stack/regs coming into a function and store them into an appropriate
  /// alloca for the argument.
  struct FunctionPrologArgumentConversion : public DefaultABIClient {
    tree FunctionDecl;
    Function::arg_iterator &AI;
    LLVMBuilder Builder;
    std::vector<Value*> LocStack;
    std::vector<std::string> NameStack;
    bool &UsedSRetBuffer;
    FunctionPrologArgumentConversion(tree FnDecl,
                                     Function::arg_iterator &ai,
                                     const LLVMBuilder &B,
                                     bool &SRetBuffer)
      : FunctionDecl(FnDecl), AI(ai), Builder(B), UsedSRetBuffer(SRetBuffer) {}

    void setName(const std::string &Name) {
      NameStack.push_back(Name);
    }
    void setLocation(Value *Loc) {
      LocStack.push_back(Loc);
    }
    void clear() {
      assert(NameStack.size() == 1 && LocStack.size() == 1 && "Imbalance!");
      NameStack.clear(); 
      LocStack.clear();
    }
    
    void HandleAggregateShadowArgument(const PointerType *PtrArgTy, 
                                       bool RetPtr) {
      // If the function returns a structure by value, we transform the function
      // to take a pointer to the result as the first argument of the function
      // instead.
      assert(AI != Builder.GetInsertBlock()->getParent()->arg_end() &&
             "No explicit return value?");
      assert(AI == Builder.GetInsertBlock()->getParent()->arg_begin() &&
             "Struct return is not first argument!");
      AI->setName("agg.result");

      tree ResultDecl = DECL_RESULT(FunctionDecl);
      tree RetTy = TREE_TYPE(TREE_TYPE(FunctionDecl));
      if (TREE_CODE(RetTy) == TREE_CODE(TREE_TYPE(ResultDecl))) {
        // Use a buffer for the return result.  This ensures that writes to the
        // return value do not interfere with reads from parameters: the same
        // aggregate might be used for the return value and as a parameter.
        TheTreeToLLVM->EmitAutomaticVariableDecl(DECL_RESULT(FunctionDecl));
        UsedSRetBuffer = true;
        ++AI;
        return;
      }

      // Otherwise, this must be something returned with NRVO.
      assert(TREE_CODE(TREE_TYPE(ResultDecl)) == REFERENCE_TYPE &&
             "Not type match and not passing by reference?");
      // Create an alloca for the ResultDecl.
      Value *Tmp = TheTreeToLLVM->CreateTemporary(AI->getType());
      Builder.CreateStore(AI, Tmp);

      SET_DECL_LLVM(ResultDecl, Tmp);
      if (TheDebugInfo) {
        TheDebugInfo->EmitDeclare(ResultDecl,
                                  llvm::dwarf::DW_TAG_return_variable,
                                  "agg.result", RetTy, Tmp,
                                  Builder.GetInsertBlock());
      }
      ++AI;
    }
    
    void HandleScalarArgument(const llvm::Type *LLVMTy, tree type) {
      Value *ArgVal = AI;
      if (ArgVal->getType() != LLVMTy) {
        if (isa<PointerType>(ArgVal->getType()) && isa<PointerType>(LLVMTy)) {
          // If this is GCC being sloppy about pointer types, insert a bitcast.
          // See PR1083 for an example.
          ArgVal = Builder.CreateBitCast(ArgVal, LLVMTy, "tmp");
        } else if (ArgVal->getType() == Type::DoubleTy) {
          // If this is a K&R float parameter, it got promoted to double. Insert
          // the truncation to float now.
          ArgVal = Builder.CreateFPTrunc(ArgVal, LLVMTy,
                                         NameStack.back().c_str());
        } else {
          // If this is just a mismatch between integer types, this is due
          // to K&R prototypes, where the forward proto defines the arg as int
          // and the actual impls is a short or char.
          assert(ArgVal->getType() == Type::Int32Ty && LLVMTy->isInteger() &&
                 "Lowerings don't match?");
          ArgVal = Builder.CreateTrunc(ArgVal, LLVMTy,NameStack.back().c_str());
        }
      }
      assert(!LocStack.empty());
      Value *Loc = LocStack.back();
      if (cast<PointerType>(Loc->getType())->getElementType() != LLVMTy)
        // This cast only involves pointers, therefore BitCast
        Loc = Builder.CreateBitCast(Loc, PointerType::getUnqual(LLVMTy), "tmp");
      
      Builder.CreateStore(ArgVal, Loc);
      AI->setName(NameStack.back());
      ++AI;
    }
        
    void HandleByValArgument(const llvm::Type *LLVMTy, tree type) {
      // Should not get here.
      abort();
    }

    void EnterField(unsigned FieldNo, const llvm::Type *StructTy) {
      NameStack.push_back(NameStack.back()+"."+utostr(FieldNo));
      
      Value *Loc = LocStack.back();
      if (cast<PointerType>(Loc->getType())->getElementType() != StructTy)
        // This cast only involves pointers, therefore BitCast
        Loc = Builder.CreateBitCast(Loc, PointerType::getUnqual(StructTy), 
                                    "tmp");

      Value *Idxs[] = {
        Constant::getNullValue(Type::Int32Ty),
        ConstantInt::get(Type::Int32Ty, FieldNo)
      };

      Loc = Builder.CreateGEP(Loc, Idxs, Idxs + 2, "tmp");
      LocStack.push_back(Loc);    
    }
    void ExitField() {
      NameStack.pop_back();
      LocStack.pop_back();
    }
  };
}

void TreeToLLVM::StartFunctionBody() {
  const char *Name = "";
  // Get the name of the function.
  if (tree ID = DECL_ASSEMBLER_NAME(FnDecl))
    Name = IDENTIFIER_POINTER(ID);
  
  // Determine the FunctionType and calling convention for this function.
  tree static_chain = cfun->static_chain_decl;
  const FunctionType *FTy;
  unsigned CallingConv;
  PAListPtr PAL;

  // If the function has no arguments and is varargs (...), turn it into a
  // non-varargs function by scanning the param list for the function.  This
  // allows C functions declared as "T foo() {}" to be treated like 
  // "T foo(void) {}" and allows us to handle functions with K&R-style
  // definitions correctly.
  if (TYPE_ARG_TYPES(TREE_TYPE(FnDecl)) == 0) {
    FTy = TheTypeConverter->ConvertArgListToFnType(TREE_TYPE(TREE_TYPE(FnDecl)),
                                                   DECL_ARGUMENTS(FnDecl),
                                                   static_chain,
                                                   CallingConv, PAL);
#ifdef TARGET_ADJUST_LLVM_CC
    TARGET_ADJUST_LLVM_CC(CallingConv, TREE_TYPE(FnDecl));
#endif
  } else {
    // Otherwise, just get the type from the function itself.
    FTy = TheTypeConverter->ConvertFunctionType(TREE_TYPE(FnDecl),
                                                FnDecl,
                                                static_chain,
                                                CallingConv, PAL);
  }
  
  // If we've already seen this function and created a prototype, and if the
  // proto has the right LLVM type, just use it.
  if (DECL_LLVM_SET_P(FnDecl) &&
      cast<PointerType>(DECL_LLVM(FnDecl)->getType())->getElementType() == FTy){
    Fn = cast<Function>(DECL_LLVM(FnDecl));
    assert(Fn->getCallingConv() == CallingConv &&
           "Calling convention disagreement between prototype and impl!");
    // The visibility can be changed from the last time we've seen this
    // function. Set to current.
    if (TREE_PUBLIC(FnDecl)) {
      if (DECL_VISIBILITY(FnDecl) == VISIBILITY_HIDDEN)
        Fn->setVisibility(Function::HiddenVisibility);
      else if (DECL_VISIBILITY(FnDecl) == VISIBILITY_PROTECTED)
        Fn->setVisibility(Function::ProtectedVisibility);
      else if (DECL_VISIBILITY(FnDecl) == VISIBILITY_DEFAULT)
        Fn->setVisibility(Function::DefaultVisibility);
    }
  } else {
    Function *FnEntry = TheModule->getFunction(Name);
    if (FnEntry) {
      assert(FnEntry->getName() == Name && "Same entry, different name?");
      assert(FnEntry->isDeclaration() &&
             "Multiple fns with same name and neither are external!");
      FnEntry->setName("");  // Clear name to avoid conflicts.
      assert(FnEntry->getCallingConv() == CallingConv &&
             "Calling convention disagreement between prototype and impl!");
    }
    
    // Otherwise, either it exists with the wrong type or it doesn't exist.  In
    // either case create a new function.
    Fn = new Function(FTy, Function::ExternalLinkage, Name, TheModule);
    assert(Fn->getName() == Name && "Preexisting fn with the same name!");
    Fn->setCallingConv(CallingConv);
    Fn->setParamAttrs(PAL);

    // If a previous proto existed with the wrong type, replace any uses of it
    // with the actual function and delete the proto.
    if (FnEntry) {
      FnEntry->replaceAllUsesWith(ConstantExpr::getBitCast(Fn,
                                                           FnEntry->getType()));
      changeLLVMValue(FnEntry, Fn);
      FnEntry->eraseFromParent();
    }
    SET_DECL_LLVM(FnDecl, Fn);
  }

  // The function should not already have a body.
  assert(Fn->empty() && "Function expanded multiple times!");
  
  // Compute the linkage that the function should get.
  if (!TREE_PUBLIC(FnDecl) /*|| lang_hooks.llvm_is_in_anon(subr)*/) {
    Fn->setLinkage(Function::InternalLinkage);
  } else if (DECL_COMDAT(FnDecl)) {
    Fn->setLinkage(Function::LinkOnceLinkage);
  } else if (DECL_WEAK(FnDecl) || DECL_ONE_ONLY(FnDecl)) {
    Fn->setLinkage(Function::WeakLinkage);
  }

#ifdef TARGET_ADJUST_LLVM_LINKAGE
  TARGET_ADJUST_LLVM_LINKAGE(Fn,FnDecl);
#endif /* TARGET_ADJUST_LLVM_LINKAGE */

  // Handle visibility style
  if (TREE_PUBLIC(FnDecl)) {
    if (DECL_VISIBILITY(FnDecl) == VISIBILITY_HIDDEN)
      Fn->setVisibility(Function::HiddenVisibility);
    else if (DECL_VISIBILITY(FnDecl) == VISIBILITY_PROTECTED)
      Fn->setVisibility(Function::ProtectedVisibility);
  }

  // Handle functions in specified sections.
  if (DECL_SECTION_NAME(FnDecl))
    Fn->setSection(TREE_STRING_POINTER(DECL_SECTION_NAME(FnDecl)));

  // Handle used Functions
  if (DECL_PRESERVE_P (FnDecl))
    AttributeUsedGlobals.insert(Fn);
  
  // Handle noinline Functions
  if (lookup_attribute ("noinline", DECL_ATTRIBUTES (FnDecl))) {
    const Type *SBP= PointerType::getUnqual(Type::Int8Ty);
    AttributeNoinlineFunctions.push_back(ConstantExpr::getBitCast(Fn,SBP));
  }
  
  // Handle annotate attributes
  if (DECL_ATTRIBUTES(FnDecl))
    AddAnnotateAttrsToGlobal(Fn, FnDecl);
  
  // Create a new basic block for the function.
  Builder.SetInsertPoint(new BasicBlock("entry", Fn));
  
  if (TheDebugInfo)
    TheDebugInfo->EmitFunctionStart(FnDecl, Fn, Builder.GetInsertBlock());
  
  // Loop over all of the arguments to the function, setting Argument names and
  // creating argument alloca's for the PARM_DECLs in case their address is
  // exposed.
  Function::arg_iterator AI = Fn->arg_begin();

  // Rename and alloca'ify real arguments.
  FunctionPrologArgumentConversion Client(FnDecl, AI, Builder, UsedSRetBuffer);
  TheLLVMABI<FunctionPrologArgumentConversion> ABIConverter(Client);

  // Handle the DECL_RESULT.
  ABIConverter.HandleReturnType(TREE_TYPE(TREE_TYPE(FnDecl)));

  // Prepend the static chain (if any) to the list of arguments.
  tree Args = static_chain ? static_chain : DECL_ARGUMENTS(FnDecl);

  while (Args) {
    const char *Name = "unnamed_arg";
    if (DECL_NAME(Args)) Name = IDENTIFIER_POINTER(DECL_NAME(Args));

    const Type *ArgTy = ConvertType(TREE_TYPE(Args));
    if (isPassedByInvisibleReference(TREE_TYPE(Args)) ||
        (!ArgTy->isFirstClassType() &&
         LLVM_SHOULD_PASS_AGGREGATE_USING_BYVAL_ATTR(TREE_TYPE(Args)))) {
      // If the value is passed by 'invisible reference' or 'byval reference',
      // the l-value for the argument IS the argument itself.
      SET_DECL_LLVM(Args, AI);
      AI->setName(Name);
      ++AI;
    } else {
      // Otherwise, we create an alloca to hold the argument value and provide
      // an l-value.  On entry to the function, we copy formal argument values
      // into the alloca.
      Value *Tmp = CreateTemporary(ArgTy);
      Tmp->setName(std::string(Name)+"_addr");
      SET_DECL_LLVM(Args, Tmp);
      if (TheDebugInfo) {
        TheDebugInfo->EmitDeclare(Args, llvm::dwarf::DW_TAG_arg_variable,
                                  Name, TREE_TYPE(Args), Tmp, 
                                  Builder.GetInsertBlock());
      }

      // Emit annotate intrinsic if arg has annotate attr
      if (DECL_ATTRIBUTES(Args))
        EmitAnnotateIntrinsic(Tmp, Args);

      // Emit gcroot intrinsic if arg has attribute
      if (POINTER_TYPE_P(TREE_TYPE(Args))
	  && lookup_attribute ("gcroot", TYPE_ATTRIBUTES(TREE_TYPE(Args))))
      	EmitTypeGcroot(Tmp, Args);
      
      Client.setName(Name);
      Client.setLocation(Tmp);
      ABIConverter.HandleArgument(TREE_TYPE(Args));
      Client.clear();
    }

    Args = Args == static_chain ? DECL_ARGUMENTS(FnDecl) : TREE_CHAIN(Args);
  }

  // If this is not a void-returning function, initialize the RESULT_DECL.
  if (DECL_RESULT(FnDecl) && !VOID_TYPE_P(TREE_TYPE(DECL_RESULT(FnDecl))) &&
      !DECL_LLVM_SET_P(DECL_RESULT(FnDecl)))
    EmitAutomaticVariableDecl(DECL_RESULT(FnDecl));

  // If this function has nested functions, we should handle a potential
  // nonlocal_goto_save_area.
  if (cfun->nonlocal_goto_save_area) {
    // Not supported yet.
  }
  
  // As it turns out, not all temporaries are associated with blocks.  For those
  // that aren't, emit them now.
  for (tree t = cfun->unexpanded_var_list; t; t = TREE_CHAIN(t)) {
    assert(!DECL_LLVM_SET_P(TREE_VALUE(t)) && "var already emitted?");
    EmitAutomaticVariableDecl(TREE_VALUE(t));
  }
  
  // Create a new block for the return node, but don't insert it yet.
  ReturnBB = new BasicBlock("return");
}

Function *TreeToLLVM::FinishFunctionBody() {
  // Insert the return block at the end of the function.
  EmitBlock(ReturnBB);
  
  Value *RetVal = 0;
  // If the function returns a value, get it into a register and return it now.
  if (Fn->getReturnType() != Type::VoidTy) {
    if (!isAggregateTreeType(TREE_TYPE(DECL_RESULT(FnDecl)))) {
      // If the DECL_RESULT is a scalar type, just load out the return value
      // and return it.
      tree TreeRetVal = DECL_RESULT(FnDecl);
      RetVal = Builder.CreateLoad(DECL_LLVM(TreeRetVal), "retval");
      bool RetValSigned = !TYPE_UNSIGNED(TREE_TYPE(TreeRetVal));
      Instruction::CastOps opcode = CastInst::getCastOpcode(
          RetVal, RetValSigned, Fn->getReturnType(), RetValSigned);
      RetVal = CastToType(opcode, RetVal, Fn->getReturnType());
    } else {
      // Otherwise, this aggregate result must be something that is returned in
      // a scalar register for this target.  We must bit convert the aggregate
      // to the specified scalar type, which we do by casting the pointer and
      // loading.
      RetVal = BitCastToType(DECL_LLVM(DECL_RESULT(FnDecl)),
                             PointerType::getUnqual(Fn->getReturnType()));
      RetVal = Builder.CreateLoad(RetVal, "retval");
    }
  } else if (UsedSRetBuffer) {
    // A buffer was used for the aggregate return result.  Copy it out now.
    assert(Fn->arg_begin() != Fn->arg_end() && "No struct return value?");
    unsigned Alignment = expr_align(DECL_RESULT(FnDecl))/8;
    bool Volatile = TREE_THIS_VOLATILE(DECL_RESULT(FnDecl));
    MemRef BufLoc(DECL_LLVM(DECL_RESULT(FnDecl)), Alignment, false);
    MemRef RetLoc(Fn->arg_begin(), Alignment, Volatile);
    EmitAggregateCopy(RetLoc, BufLoc, TREE_TYPE(DECL_RESULT(FnDecl)));
  }
  if (TheDebugInfo) TheDebugInfo->EmitRegionEnd(Fn, Builder.GetInsertBlock());
  Builder.CreateRet(RetVal);
  
  // If this function has exceptions, emit the lazily created unwind block.
  if (UnwindBB) {
    EmitBlock(UnwindBB);
#ifdef ITANIUM_STYLE_EXCEPTIONS
    if (ExceptionValue) {
      // Fetch and store exception handler.
      Value *Arg = Builder.CreateLoad(ExceptionValue, "eh_ptr");
      Builder.CreateCall(FuncUnwindResume, Arg);
      Builder.CreateUnreachable();
    } else {
      new UnwindInst(UnwindBB);
    }
#else
    new UnwindInst(UnwindBB);
#endif
  }
  
  // If this function takes the address of a label, emit the indirect goto
  // block.
  if (IndirectGotoBlock) {
    EmitBlock(IndirectGotoBlock);
    
    // Change the default destination to go to one of the other destinations, if
    // there is any other dest.
    SwitchInst *SI = cast<SwitchInst>(IndirectGotoBlock->getTerminator());
    if (SI->getNumSuccessors() > 1)
      SI->setSuccessor(0, SI->getSuccessor(1));
  }

  // Remove any cached LLVM values that are local to this function.  Such values
  // may be deleted when the optimizers run, so would be dangerous to keep.
  eraseLocalLLVMValues();

  return Fn;
}


Value *TreeToLLVM::Emit(tree exp, const MemRef *DestLoc) {
  assert((isAggregateTreeType(TREE_TYPE(exp)) == (DestLoc != 0) ||
          TREE_CODE(exp) == MODIFY_EXPR) &&
         "Didn't pass DestLoc to an aggregate expr, or passed it to scalar!");
  
  Value *Result = 0;
  
  if (TheDebugInfo) {
    if (EXPR_HAS_LOCATION(exp)) {
      // Set new location on the way up the tree.
      TheDebugInfo->setLocationFile(EXPR_FILENAME(exp));
      TheDebugInfo->setLocationLine(EXPR_LINENO(exp));
    }
  
    // These node create an artificial jump to end of block.  
    if (TREE_CODE(exp) != BIND_EXPR && TREE_CODE(exp) != STATEMENT_LIST)
      TheDebugInfo->EmitStopPoint(Fn, Builder.GetInsertBlock());
  }
  
  switch (TREE_CODE(exp)) {
  default:
    std::cerr << "Unhandled expression!\n";
    debug_tree(exp);
    abort();
    
  // Basic lists and binding scopes
  case BIND_EXPR:      Result = EmitBIND_EXPR(exp, DestLoc); break;
  case STATEMENT_LIST: Result = EmitSTATEMENT_LIST(exp, DestLoc); break;

  // Control flow
  case LABEL_EXPR:     Result = EmitLABEL_EXPR(exp); break;
  case GOTO_EXPR:      Result = EmitGOTO_EXPR(exp); break;
  case RETURN_EXPR:    Result = EmitRETURN_EXPR(exp, DestLoc); break;
  case COND_EXPR:      Result = EmitCOND_EXPR(exp); break;
  case SWITCH_EXPR:    Result = EmitSWITCH_EXPR(exp); break;
  case TRY_FINALLY_EXPR:
  case TRY_CATCH_EXPR: Result = EmitTRY_EXPR(exp); break;
  case EXC_PTR_EXPR:   Result = EmitEXC_PTR_EXPR(exp); break;
  case CATCH_EXPR:     Result = EmitCATCH_EXPR(exp); break;
  case EH_FILTER_EXPR: Result = EmitEH_FILTER_EXPR(exp); break;
    
  // Expressions
  case VAR_DECL:
  case PARM_DECL:
  case RESULT_DECL:
  case INDIRECT_REF:
  case ARRAY_REF:
  case ARRAY_RANGE_REF:
  case COMPONENT_REF:
  case BIT_FIELD_REF:
  case STRING_CST:
  case REALPART_EXPR:
  case IMAGPART_EXPR:
    Result = EmitLoadOfLValue(exp, DestLoc);
    break;
  case OBJ_TYPE_REF:   Result = EmitOBJ_TYPE_REF(exp); break;
  case ADDR_EXPR:      Result = EmitADDR_EXPR(exp); break;
  case CALL_EXPR:      Result = EmitCALL_EXPR(exp, DestLoc); break;
  case MODIFY_EXPR:    Result = EmitMODIFY_EXPR(exp, DestLoc); break;
  case ASM_EXPR:       Result = EmitASM_EXPR(exp); break;
  case NON_LVALUE_EXPR: Result = Emit(TREE_OPERAND(exp, 0), DestLoc); break;

    // Unary Operators
  case NOP_EXPR:       Result = EmitNOP_EXPR(exp, DestLoc); break;
  case FIX_TRUNC_EXPR:
  case FLOAT_EXPR:
  case CONVERT_EXPR:   Result = EmitCONVERT_EXPR(exp, DestLoc); break;
  case VIEW_CONVERT_EXPR: Result = EmitVIEW_CONVERT_EXPR(exp, DestLoc); break;
  case NEGATE_EXPR:    Result = EmitNEGATE_EXPR(exp, DestLoc); break;
  case CONJ_EXPR:      Result = EmitCONJ_EXPR(exp, DestLoc); break;
  case ABS_EXPR:       Result = EmitABS_EXPR(exp); break;
  case BIT_NOT_EXPR:   Result = EmitBIT_NOT_EXPR(exp); break;
  case TRUTH_NOT_EXPR: Result = EmitTRUTH_NOT_EXPR(exp); break;

  // Binary Operators
  case LT_EXPR: 
    Result = EmitCompare(exp, ICmpInst::ICMP_ULT, ICmpInst::ICMP_SLT, 
                         FCmpInst::FCMP_OLT);
    break;
  case LE_EXPR:
    Result = EmitCompare(exp, ICmpInst::ICMP_ULE, ICmpInst::ICMP_SLE,
                         FCmpInst::FCMP_OLE);
    break;
  case GT_EXPR:
    Result = EmitCompare(exp, ICmpInst::ICMP_UGT, ICmpInst::ICMP_SGT,
                         FCmpInst::FCMP_OGT);
    break;
  case GE_EXPR:
    Result = EmitCompare(exp, ICmpInst::ICMP_UGE, ICmpInst::ICMP_SGE, 
                         FCmpInst::FCMP_OGE);
    break;
  case EQ_EXPR:
    Result = EmitCompare(exp, ICmpInst::ICMP_EQ, ICmpInst::ICMP_EQ, 
                         FCmpInst::FCMP_OEQ);
    break;
  case NE_EXPR:
    Result = EmitCompare(exp, ICmpInst::ICMP_NE, ICmpInst::ICMP_NE, 
                         FCmpInst::FCMP_UNE);
    break;
  case UNORDERED_EXPR: 
    Result = EmitCompare(exp, 0, 0, FCmpInst::FCMP_UNO);
    break;
  case ORDERED_EXPR: 
    Result = EmitCompare(exp, 0, 0, FCmpInst::FCMP_ORD);
    break;
  case UNLT_EXPR: Result = EmitCompare(exp, 0, 0, FCmpInst::FCMP_ULT); break;
  case UNLE_EXPR: Result = EmitCompare(exp, 0, 0, FCmpInst::FCMP_ULE); break;
  case UNGT_EXPR: Result = EmitCompare(exp, 0, 0, FCmpInst::FCMP_UGT); break;
  case UNGE_EXPR: Result = EmitCompare(exp, 0, 0, FCmpInst::FCMP_UGE); break;
  case UNEQ_EXPR: Result = EmitCompare(exp, 0, 0, FCmpInst::FCMP_UEQ); break;
  case LTGT_EXPR: Result = EmitCompare(exp, 0, 0, FCmpInst::FCMP_ONE); break;
  case PLUS_EXPR: Result = EmitBinOp(exp, DestLoc, Instruction::Add);break;
  case MINUS_EXPR:Result = EmitBinOp(exp, DestLoc, Instruction::Sub);break;
  case MULT_EXPR: Result = EmitBinOp(exp, DestLoc, Instruction::Mul);break;
  case EXACT_DIV_EXPR: Result = EmitEXACT_DIV_EXPR(exp, DestLoc); break;
  case TRUNC_DIV_EXPR: 
    if (TYPE_UNSIGNED(TREE_TYPE(exp)))
      Result = EmitBinOp(exp, DestLoc, Instruction::UDiv);
    else 
      Result = EmitBinOp(exp, DestLoc, Instruction::SDiv);
    break;
  case RDIV_EXPR: Result = EmitBinOp(exp, DestLoc, Instruction::FDiv); break;
  case CEIL_DIV_EXPR: Result = EmitCEIL_DIV_EXPR(exp); break;
  case ROUND_DIV_EXPR: Result = EmitROUND_DIV_EXPR(exp); break;
  case TRUNC_MOD_EXPR: 
    if (TYPE_UNSIGNED(TREE_TYPE(exp)))
      Result = EmitBinOp(exp, DestLoc, Instruction::URem);
    else
      Result = EmitBinOp(exp, DestLoc, Instruction::SRem);
    break;
  case FLOOR_MOD_EXPR: Result = EmitFLOOR_MOD_EXPR(exp, DestLoc); break;
  case BIT_AND_EXPR:   Result = EmitBinOp(exp, DestLoc, Instruction::And);break;
  case BIT_IOR_EXPR:   Result = EmitBinOp(exp, DestLoc, Instruction::Or );break;
  case BIT_XOR_EXPR:   Result = EmitBinOp(exp, DestLoc, Instruction::Xor);break;
  case TRUTH_AND_EXPR: Result = EmitTruthOp(exp, Instruction::And); break;
  case TRUTH_OR_EXPR:  Result = EmitTruthOp(exp, Instruction::Or); break;
  case TRUTH_XOR_EXPR: Result = EmitTruthOp(exp, Instruction::Xor); break;
  case RSHIFT_EXPR:
    Result = EmitShiftOp(exp,DestLoc,
       TYPE_UNSIGNED(TREE_TYPE(exp)) ? Instruction::LShr : Instruction::AShr);
    break;
  case LSHIFT_EXPR:    Result = EmitShiftOp(exp,DestLoc,Instruction::Shl);break;
  case RROTATE_EXPR: 
    Result = EmitRotateOp(exp, Instruction::LShr, Instruction::Shl);
    break;
  case LROTATE_EXPR:
    Result = EmitRotateOp(exp, Instruction::Shl, Instruction::LShr);
    break;
  case MIN_EXPR: 
    Result = EmitMinMaxExpr(exp, ICmpInst::ICMP_ULE, ICmpInst::ICMP_SLE, 
                            FCmpInst::FCMP_OLE);
    break;
  case MAX_EXPR:
    Result = EmitMinMaxExpr(exp, ICmpInst::ICMP_UGE, ICmpInst::ICMP_SGE,
                            FCmpInst::FCMP_OGE);
    break;
  case CONSTRUCTOR:    Result = EmitCONSTRUCTOR(exp, DestLoc); break;
    
  // Complex Math Expressions.
  case COMPLEX_CST:    EmitCOMPLEX_CST (exp, DestLoc); break;
  case COMPLEX_EXPR:   EmitCOMPLEX_EXPR(exp, DestLoc); break;
    
  // Constant Expressions
  case INTEGER_CST:
    if (!DestLoc)
      Result = TreeConstantToLLVM::ConvertINTEGER_CST(exp);
    else
      EmitINTEGER_CST_Aggregate(exp, DestLoc);
    break;
  case REAL_CST:
    Result = TreeConstantToLLVM::ConvertREAL_CST(exp);
    break;
  case VECTOR_CST:
    Result = TreeConstantToLLVM::ConvertVECTOR_CST(exp);
    break;
  }
  
  // If this is an operation on an integer value in a precision smaller than
  // the LLVM value we are computing it in, reduce the excess precision here.
  // This happens with odd-sized bitfields (e.g. i33) that are evaluated in the
  // next size power-of-two register (e.g. i64).  This should be reevaluated
  // when we have good support for unusual sized integers in the code generator.
  if (Result && TREE_CODE(TREE_TYPE(exp)) == INTEGER_TYPE) {
    unsigned LLVMWidth = Result->getType()->getPrimitiveSizeInBits();
    unsigned TreeWidth = TYPE_PRECISION(TREE_TYPE(exp));
    if (LLVMWidth > TreeWidth && lang_hooks.reduce_bit_field_operations) {
      if (TYPE_UNSIGNED(TREE_TYPE(exp))) {
        // Use an 'and' to clear excess top bits.
        Constant *Mask =
          ConstantInt::get(APInt::getLowBitsSet(LLVMWidth, TreeWidth));
        Result = Builder.CreateAnd(Result, Mask, "mask");
      } else {
        // Shift Left then shift right.
        Constant *ShAmt = ConstantInt::get(Result->getType(), 
                                           LLVMWidth-TreeWidth);
        Result = Builder.CreateShl(Result, ShAmt, "sextl");
        Result = Builder.CreateAShr(Result, ShAmt, "sextr");
      }
    }
  }
  
  if (TheDebugInfo && EXPR_HAS_LOCATION(exp)) {
    // Restore location back down the tree.
    TheDebugInfo->setLocationFile(EXPR_FILENAME(exp));
    TheDebugInfo->setLocationLine(EXPR_LINENO(exp));
  }

  assert(((DestLoc && Result == 0) || DestLoc == 0) &&
         "Expected a scalar or aggregate but got the wrong thing!"); 
  return Result;
}

/// EmitLV - Convert the specified l-value tree node to LLVM code, returning
/// the address of the result.
LValue TreeToLLVM::EmitLV(tree exp) {
  switch (TREE_CODE(exp)) {
  default:
    std::cerr << "Unhandled lvalue expression!\n";
    debug_tree(exp);
    abort();
  
  case PARM_DECL:
  case VAR_DECL:
  case FUNCTION_DECL:
  case CONST_DECL:
  case RESULT_DECL:   return EmitLV_DECL(exp);
  case ARRAY_RANGE_REF:
  case ARRAY_REF:     return EmitLV_ARRAY_REF(exp);
  case COMPONENT_REF: return EmitLV_COMPONENT_REF(exp);
  case BIT_FIELD_REF: return EmitLV_BIT_FIELD_REF(exp);
  case REALPART_EXPR: return EmitLV_XXXXPART_EXPR(exp, 0);
  case IMAGPART_EXPR: return EmitLV_XXXXPART_EXPR(exp, 1);

  // Constants.
  case LABEL_DECL:    return TreeConstantToLLVM::EmitLV_LABEL_DECL(exp);
  case STRING_CST:    return LValue(TreeConstantToLLVM::EmitLV_STRING_CST(exp));

  // Type Conversion.
  case VIEW_CONVERT_EXPR: return EmitLV_VIEW_CONVERT_EXPR(exp);

  // Trivial Cases.
  case WITH_SIZE_EXPR:
    // The address is the address of the operand.
    return EmitLV(TREE_OPERAND(exp, 0));
  case INDIRECT_REF:
    // The lvalue is just the address.
    return Emit(TREE_OPERAND(exp, 0), 0);
  }
}

//===----------------------------------------------------------------------===//
//                         ... Utility Functions ...
//===----------------------------------------------------------------------===//

void TreeToLLVM::TODO(tree exp) {
  std::cerr << "Unhandled tree node\n";
  if (exp) debug_tree(exp);
  abort();  
}

/// CastToType - Cast the specified value to the specified type if it is
/// not already that type.
Value *TreeToLLVM::CastToType(unsigned opcode, Value *V, const Type* Ty) {
  // Eliminate useless casts of a type to itself.
  if (V->getType() == Ty) 
    return V;

  // If this is a simple constant operand, fold it now.  If it is a constant
  // expr operand, fold it below.
  if (Constant *C = dyn_cast<Constant>(V))
    if (!isa<ConstantExpr>(C))
      return ConstantExpr::getCast(Instruction::CastOps(opcode), C, Ty);
  
  // Handle 'trunc (zext i1 X to T2) to i1' as X, because this occurs all over
  // the place.
  if (ZExtInst *CI = dyn_cast<ZExtInst>(V))
    if (Ty == Type::Int1Ty && CI->getOperand(0)->getType() == Type::Int1Ty)
      return CI->getOperand(0);
  Value *Result = Builder.CreateCast(Instruction::CastOps(opcode), V, Ty,
                                     V->getNameStart());

  // If this is a constantexpr, fold the instruction with
  // ConstantFoldInstruction to allow TargetData-driven folding to occur.
  if (isa<ConstantExpr>(V))
    Result = ConstantFoldInstruction(cast<Instruction>(Result), &TD);
  
  return Result;
}

/// CastToAnyType - Cast the specified value to the specified type making no
/// assumptions about the types of the arguments. This creates an inferred cast.
Value *TreeToLLVM::CastToAnyType(Value *V, bool VisSigned, 
                                 const Type* Ty, bool TyIsSigned) {
  // Eliminate useless casts of a type to itself.
  if (V->getType() == Ty)
    return V;

  // The types are different so we must cast. Use getCastOpcode to create an
  // inferred cast opcode.
  Instruction::CastOps opc = 
    CastInst::getCastOpcode(V, VisSigned, Ty, TyIsSigned);

  // Generate the cast and return it.
  return CastToType(opc, V, Ty);
}

/// CastToUIntType - Cast the specified value to the specified type assuming
/// that the value and type are unsigned integer types.
Value *TreeToLLVM::CastToUIntType(Value *V, const Type* Ty) {
  // Eliminate useless casts of a type to itself.
  if (V->getType() == Ty)
    return V;

  unsigned SrcBits = V->getType()->getPrimitiveSizeInBits();
  unsigned DstBits = Ty->getPrimitiveSizeInBits();
  assert(SrcBits != DstBits && "Types are different but have same #bits?");

  Instruction::CastOps opcode = 
    (SrcBits > DstBits ? Instruction::Trunc : Instruction::ZExt);
  return CastToType(opcode, V, Ty);
}

/// CastToSIntType - Cast the specified value to the specified type assuming
/// that the value and type are signed integer types.
Value *TreeToLLVM::CastToSIntType(Value *V, const Type* Ty) {
  // Eliminate useless casts of a type to itself.
  if (V->getType() == Ty)
    return V;

  unsigned SrcBits = V->getType()->getPrimitiveSizeInBits();
  unsigned DstBits = Ty->getPrimitiveSizeInBits();
  assert(SrcBits != DstBits && "Types are different but have same #bits?");

  Instruction::CastOps opcode = 
    (SrcBits > DstBits ? Instruction::Trunc : Instruction::SExt);
  return CastToType(opcode, V, Ty);
}

/// CastToFPType - Cast the specified value to the specified type assuming
/// that the value and type or floating point
Value *TreeToLLVM::CastToFPType(Value *V, const Type* Ty) {
  unsigned SrcBits = V->getType()->getPrimitiveSizeInBits();
  unsigned DstBits = Ty->getPrimitiveSizeInBits();
  if (SrcBits == DstBits)
    return V;
  Instruction::CastOps opcode = (SrcBits > DstBits ? 
      Instruction::FPTrunc : Instruction::FPExt);
  return CastToType(opcode, V, Ty);
}

/// BitCastToType - Insert a BitCast from V to Ty if needed. This is just a 
/// shorthand convenience function for CastToType(Instruction::BitCast,V,Ty).
Value *TreeToLLVM::BitCastToType(Value *V, const Type *Ty) {
  return CastToType(Instruction::BitCast, V, Ty);
}

/// CreateTemporary - Create a new alloca instruction of the specified type,
/// inserting it into the entry block and returning it.  The resulting
/// instruction's type is a pointer to the specified type.
AllocaInst *TreeToLLVM::CreateTemporary(const Type *Ty) {
  if (AllocaInsertionPoint == 0) {
    // Create a dummy instruction in the entry block as a marker to insert new
    // alloc instructions before.  It doesn't matter what this instruction is,
    // it is dead.  This allows us to insert allocas in order without having to
    // scan for an insertion point. Use BitCast for int -> int
    AllocaInsertionPoint = CastInst::create(Instruction::BitCast,
      Constant::getNullValue(Type::Int32Ty), Type::Int32Ty, "alloca point");
    // Insert it as the first instruction in the entry block.
    Fn->begin()->getInstList().insert(Fn->begin()->begin(),
                                      AllocaInsertionPoint);
  }
  return new AllocaInst(Ty, 0, "memtmp", AllocaInsertionPoint);
}

/// CreateTempLoc - Like CreateTemporary, but returns a MemRef.
MemRef TreeToLLVM::CreateTempLoc(const Type *Ty) {
  AllocaInst *AI = CreateTemporary(Ty);
  // MemRefs do not allow alignment 0.
  if (!AI->getAlignment())
    AI->setAlignment(TD.getPrefTypeAlignment(Ty));
  return MemRef(AI, AI->getAlignment(), false);
}

/// EmitBlock - Add the specified basic block to the end of the function.  If
/// the previous block falls through into it, add an explicit branch.  Also,
/// manage fixups for EH info.
void TreeToLLVM::EmitBlock(BasicBlock *BB) {
  BasicBlock *CurBB = Builder.GetInsertBlock();
  // If the previous block falls through to BB, add an explicit branch.
  if (CurBB->getTerminator() == 0) {
    // If the previous block has no label and is empty, remove it: it is a
    // post-terminator block.
    if (CurBB->getName().empty() && CurBB->begin() == CurBB->end()) {
      CurBB->eraseFromParent();
      
      if (!CurrentEHScopes.empty()) {
        assert(CurrentEHScopes.back().Blocks.back() == CurBB);
        CurrentEHScopes.back().Blocks.pop_back();
        BlockEHScope.erase(CurBB);
      }
    } else {
      // Otherwise, fall through to this block.
      Builder.CreateBr(BB);
    }
  }
  
  // Add this block.
  Fn->getBasicBlockList().push_back(BB);
  Builder.SetInsertPoint(BB);  // It is now the current block.

  // If there are no exception scopes that contain this block, exit.  This is
  // common for C++ code and almost uniformly true for C code.
  if (CurrentEHScopes.empty()) return;
  
  // Otherwise, we now know that this block is in this exception scope.  Update
  // records.
  CurrentEHScopes.back().Blocks.push_back(BB);
  BlockEHScope[BB] = CurrentEHScopes.size()-1;
}

/// CopyAggregate - Recursively traverse the potientially aggregate src/dest
/// ptrs, copying all of the elements.
static void CopyAggregate(MemRef DestLoc, MemRef SrcLoc, LLVMBuilder &Builder) {
  assert(DestLoc.Ptr->getType() == SrcLoc.Ptr->getType() &&
         "Cannot copy between two pointers of different type!");
  const Type *ElTy =
    cast<PointerType>(DestLoc.Ptr->getType())->getElementType();

  unsigned Alignment = std::min(DestLoc.Alignment, SrcLoc.Alignment);

  if (ElTy->isFirstClassType()) {
    LoadInst *V = Builder.CreateLoad(SrcLoc.Ptr, SrcLoc.Volatile, "tmp");
    StoreInst *S = Builder.CreateStore(V, DestLoc.Ptr, DestLoc.Volatile);
    V->setAlignment(Alignment);
    S->setAlignment(Alignment);
  } else if (const StructType *STy = dyn_cast<StructType>(ElTy)) {
    const StructLayout *SL = getTargetData().getStructLayout(STy);
    Constant *Zero = ConstantInt::get(Type::Int32Ty, 0);
    for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
      if (isPaddingElement(STy, i))
        continue;
      Constant *Idx = ConstantInt::get(Type::Int32Ty, i);
      Value *Idxs[2] = { Zero, Idx };
      Value *DElPtr = Builder.CreateGEP(DestLoc.Ptr, Idxs, Idxs + 2, "tmp");
      Value *SElPtr = Builder.CreateGEP(SrcLoc.Ptr, Idxs, Idxs + 2, "tmp");
      unsigned Align = MinAlign(Alignment, SL->getElementOffset(i));
      CopyAggregate(MemRef(DElPtr, Align, DestLoc.Volatile),
                    MemRef(SElPtr, Align, SrcLoc.Volatile),
                    Builder);
    }
  } else {
    const ArrayType *ATy = cast<ArrayType>(ElTy);
    Constant *Zero = ConstantInt::get(Type::Int32Ty, 0);
    unsigned EltSize = getTargetData().getABITypeSize(ATy->getElementType());
    for (unsigned i = 0, e = ATy->getNumElements(); i != e; ++i) {
      Constant *Idx = ConstantInt::get(Type::Int32Ty, i);
      Value *Idxs[2] = { Zero, Idx };
      Value *DElPtr = Builder.CreateGEP(DestLoc.Ptr, Idxs, Idxs + 2, "tmp");
      Value *SElPtr = Builder.CreateGEP(SrcLoc.Ptr, Idxs, Idxs + 2, "tmp");
      unsigned Align = MinAlign(Alignment, i * EltSize);
      CopyAggregate(MemRef(DElPtr, Align, DestLoc.Volatile),
                    MemRef(SElPtr, Align, SrcLoc.Volatile),
                    Builder);
    }
  }
}

/// CountAggregateElements - Return the number of elements in the specified type
/// that will need to be loaded/stored if we copy this by explicit accesses.
static unsigned CountAggregateElements(const Type *Ty) {
  if (Ty->isFirstClassType()) return 1;

  if (const StructType *STy = dyn_cast<StructType>(Ty)) {
    unsigned NumElts = 0;
    for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i)
      NumElts += CountAggregateElements(STy->getElementType(i));
    return NumElts;
  } else {
    const ArrayType *ATy = cast<ArrayType>(Ty);
    return ATy->getNumElements()*CountAggregateElements(ATy->getElementType());
  }
}

#ifndef TARGET_LLVM_MIN_BYTES_COPY_BY_MEMCPY
#define TARGET_LLVM_MIN_BYTES_COPY_BY_MEMCPY 64
#endif

/// EmitAggregateCopy - Copy the elements from SrcLoc to DestLoc, using the
/// GCC type specified by GCCType to know which elements to copy.
void TreeToLLVM::EmitAggregateCopy(MemRef DestLoc, MemRef SrcLoc, tree type) {
  if (DestLoc.Ptr == SrcLoc.Ptr && !DestLoc.Volatile && !SrcLoc.Volatile)
    return;  // noop copy.

  // If the type is small, copy the elements instead of using a block copy.
  if (TREE_CODE(TYPE_SIZE(type)) == INTEGER_CST &&
      TREE_INT_CST_LOW(TYPE_SIZE_UNIT(type)) <
          TARGET_LLVM_MIN_BYTES_COPY_BY_MEMCPY) {
    const Type *LLVMTy = ConvertType(type);
    
    // If the GCC type is not fully covered by the LLVM type, use memcpy. This
    // can occur with unions etc.
    if (!TheTypeConverter->GCCTypeOverlapsWithLLVMTypePadding(type, LLVMTy) && 
        // Don't copy tons of tiny elements.
        CountAggregateElements(LLVMTy) <= 8) {
      DestLoc.Ptr = CastToType(Instruction::BitCast, DestLoc.Ptr,
                               PointerType::getUnqual(LLVMTy));
      SrcLoc.Ptr = CastToType(Instruction::BitCast, SrcLoc.Ptr,
                              PointerType::getUnqual(LLVMTy));
      CopyAggregate(DestLoc, SrcLoc, Builder);
      return;
    }
  }
  
  Value *TypeSize = Emit(TYPE_SIZE_UNIT(type), 0);
  EmitMemCpy(DestLoc.Ptr, SrcLoc.Ptr, TypeSize,
             std::min(DestLoc.Alignment, SrcLoc.Alignment));
}

/// ZeroAggregate - Recursively traverse the potentially aggregate DestLoc,
/// zero'ing all of the elements.
static void ZeroAggregate(MemRef DestLoc, LLVMBuilder &Builder) {
  const Type *ElTy =
    cast<PointerType>(DestLoc.Ptr->getType())->getElementType();
  if (ElTy->isFirstClassType()) {
    StoreInst *St = Builder.CreateStore(Constant::getNullValue(ElTy),
                                        DestLoc.Ptr, DestLoc.Volatile);
    St->setAlignment(DestLoc.Alignment);
  } else if (const StructType *STy = dyn_cast<StructType>(ElTy)) {
    const StructLayout *SL = getTargetData().getStructLayout(STy);
    Constant *Zero = ConstantInt::get(Type::Int32Ty, 0);
    for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
      Constant *Idx = ConstantInt::get(Type::Int32Ty, i);
      Value *Idxs[2] = { Zero, Idx };
      Value *Ptr = Builder.CreateGEP(DestLoc.Ptr, Idxs, Idxs + 2, "tmp");
      unsigned Alignment = MinAlign(DestLoc.Alignment, SL->getElementOffset(i));
      ZeroAggregate(MemRef(Ptr, Alignment, DestLoc.Volatile), Builder);
    }
  } else {
    const ArrayType *ATy = cast<ArrayType>(ElTy);
    Constant *Zero = ConstantInt::get(Type::Int32Ty, 0);
    unsigned EltSize = getTargetData().getABITypeSize(ATy->getElementType());
    for (unsigned i = 0, e = ATy->getNumElements(); i != e; ++i) {
      Constant *Idx = ConstantInt::get(Type::Int32Ty, i);
      Value *Idxs[2] = { Zero, Idx };
      Value *Ptr = Builder.CreateGEP(DestLoc.Ptr, Idxs, Idxs + 2, "tmp");
      unsigned Alignment = MinAlign(DestLoc.Alignment, i * EltSize);
      ZeroAggregate(MemRef(Ptr, Alignment, DestLoc.Volatile), Builder);
    }
  }
}

/// EmitAggregateZero - Zero the elements of DestPtr.
///
void TreeToLLVM::EmitAggregateZero(MemRef DestLoc, tree type) {
  // If the type is small, copy the elements instead of using a block copy.
  if (TREE_CODE(TYPE_SIZE(type)) == INTEGER_CST &&
      TREE_INT_CST_LOW(TYPE_SIZE_UNIT(type)) < 128) {
    const Type *LLVMTy = ConvertType(type);

    // If the GCC type is not fully covered by the LLVM type, use memset. This
    // can occur with unions etc.
    if (!TheTypeConverter->GCCTypeOverlapsWithLLVMTypePadding(type, LLVMTy) &&
        // Don't zero tons of tiny elements.
        CountAggregateElements(LLVMTy) <= 8) {
      DestLoc.Ptr = CastToType(Instruction::BitCast, DestLoc.Ptr,
                               PointerType::getUnqual(LLVMTy));

      ZeroAggregate(DestLoc, Builder);
      return;
    }
  }

  EmitMemSet(DestLoc.Ptr, ConstantInt::get(Type::Int8Ty, 0),
             Emit(TYPE_SIZE_UNIT(type), 0), DestLoc.Alignment);
}

void TreeToLLVM::EmitMemCpy(Value *DestPtr, Value *SrcPtr, Value *Size, 
                            unsigned Align) {
  const Type *SBP = PointerType::getUnqual(Type::Int8Ty);
  const Type *IntPtr = TD.getIntPtrType();
  Value *Ops[4] = {
    CastToType(Instruction::BitCast, DestPtr, SBP),
    CastToType(Instruction::BitCast, SrcPtr, SBP),
    CastToSIntType(Size, IntPtr),
    ConstantInt::get(Type::Int32Ty, Align)
  };

  Intrinsic::ID IID = 
    (IntPtr == Type::Int32Ty) ? Intrinsic::memcpy_i32 : Intrinsic::memcpy_i64;
  Builder.CreateCall(Intrinsic::getDeclaration(TheModule, IID), Ops, Ops+4);
}

void TreeToLLVM::EmitMemMove(Value *DestPtr, Value *SrcPtr, Value *Size, 
                             unsigned Align) {
  const Type *SBP = PointerType::getUnqual(Type::Int8Ty);
  const Type *IntPtr = TD.getIntPtrType();
  Value *Ops[4] = {
    CastToType(Instruction::BitCast, DestPtr, SBP),
    CastToType(Instruction::BitCast, SrcPtr, SBP),
    CastToSIntType(Size, IntPtr),
    ConstantInt::get(Type::Int32Ty, Align)
  };

  Intrinsic::ID IID = 
    (IntPtr == Type::Int32Ty) ? Intrinsic::memmove_i32 : Intrinsic::memmove_i64;
  Builder.CreateCall(Intrinsic::getDeclaration(TheModule, IID), Ops, Ops+4);
}

void TreeToLLVM::EmitMemSet(Value *DestPtr, Value *SrcVal, Value *Size, 
                            unsigned Align) {
  const Type *SBP = PointerType::getUnqual(Type::Int8Ty);
  const Type *IntPtr = TD.getIntPtrType();
  Value *Ops[4] = {
    CastToType(Instruction::BitCast, DestPtr, SBP),
    CastToSIntType(SrcVal, Type::Int8Ty),
    CastToSIntType(Size, IntPtr),
    ConstantInt::get(Type::Int32Ty, Align)
  };

  Intrinsic::ID IID = 
    (IntPtr == Type::Int32Ty) ? Intrinsic::memset_i32 : Intrinsic::memset_i64;
  
  Builder.CreateCall(Intrinsic::getDeclaration(TheModule, IID), Ops, Ops+4);
}


/// EmitBranchInternal - Emit an unconditional branch to the specified basic
/// block, running cleanups if the branch exits scopes.  The arguments specify
/// how to handle these cleanups.
///
/// This function is used for a variety of control flow purposes. In particular,
/// it is responsible for determining which cleanups must be executed as a
/// result of leaving blocks with destructors.  For branches that require
/// cleanups, it schedules cleanup insertion with a goto_fixup record.  When the
/// block containing the cleanup is exited, the end-of-block code inserts the
/// cleanups as indicated by goto_fixups.
///
/// Note that some cleanups only apply to exception edges.  If this is an
/// exception edge (as indicated by IsExceptionEdge) these are expanded,
/// otherwise not.
///
/// Note that all calling code should emit a new basic block after this, so that
/// future code does not fall after the terminator.
///
void TreeToLLVM::EmitBranchInternal(BasicBlock *Dest, bool IsExceptionEdge) {
  // Insert the branch.
  BranchInst *BI = Builder.CreateBr(Dest);

  // If there are no current exception scopes, this edge *couldn't* need
  // cleanups.  It is not possible to jump into a scope that requires a cleanup.
  // This keeps the C case fast.
  if (CurrentEHScopes.empty()) return;

  // If the destination block has already been emitted, this is a backwards
  // branch, and we can resolve it now.
  if (Dest->getParent()) {
    // This is a forward reference to a block.  Since we know that we can't jump
    // INTO a region that has cleanups, we can only be branching out.
    std::map<BasicBlock*, unsigned>::iterator I = BlockEHScope.find(Dest);
    if (I != BlockEHScope.end() && I->second == CurrentEHScopes.size() - 1)
      return;  // Branch within the same EH scope.

    assert((I == BlockEHScope.end() || I->second < CurrentEHScopes.size()) &&
           "Invalid branch into EH region");
  }

  AddBranchFixup(BI, IsExceptionEdge);
}

/// AddBranchFixup - Add the specified unconditional branch to the fixup list
/// for the outermost exception scope, merging it if there is already a fixup
/// that works.
void TreeToLLVM::AddBranchFixup(BranchInst *BI, bool isExceptionEdge) {
  BasicBlock *Dest = BI->getSuccessor(0);

  // Check to see if we already have a fixup for this destination.
  std::vector<BranchFixup> &BranchFixups = CurrentEHScopes.back().BranchFixups;
  for (unsigned i = 0, e = BranchFixups.size(); i != e; ++i)
    if (BranchFixups[i].SrcBranch->getSuccessor(0) == Dest &&
        BranchFixups[i].isExceptionEdge == isExceptionEdge) {
      BranchFixup &Fixup = BranchFixups[i];
      // We found a fixup for this destination already.  Recycle it.
      if (&Fixup.SrcBranch->getParent()->front() == Fixup.SrcBranch) {
        // If the fixup's branch is the only instruction in its block, change
        // the branch we just emitted to branch to that block instead.
        BI->setSuccessor(0, Fixup.SrcBranch->getParent());
        return;
      }
      
      if (&Builder.GetInsertBlock()->front() == BI) {
        // Otherwise, if this block is empty except for the branch, change the
        // fixup to jump here and change the fixup to fix this branch.
        Fixup.SrcBranch->setSuccessor(0, Builder.GetInsertBlock());
        Fixup.SrcBranch = BI;
        return;
      }
      
      // Finally, if neither block is empty, create a new (empty) one and
      // revector BOTH branches to the new block.
      EmitBlock(new BasicBlock("cleanup"));
      BranchInst *NewBI = Builder.CreateBr(Dest);
      BI->setSuccessor(0, Builder.GetInsertBlock());
      Fixup.SrcBranch->setSuccessor(0, Builder.GetInsertBlock());
      Fixup.SrcBranch = NewBI;
      return;
    }
  
  // Otherwise, create a new fixup for this branch so we know that it needs
  // cleanups when we finish up the scopes that it is in.
  BranchFixups.push_back(BranchFixup(BI, isExceptionEdge));
}

// Emits code to do something for a type attribute
void TreeToLLVM::EmitTypeGcroot(Value *V, tree decl) {
  // GC intrinsics can only be used in functions which specify a collector.
  Fn->setCollector("shadow-stack");

  Function *gcrootFun = Intrinsic::getDeclaration(TheModule,
						  Intrinsic::gcroot);
  
  // The idea is that it's a pointer to type "Value"
  // which is opaque* but the routine expects i8** and i8*.
  const PointerType *Ty = PointerType::getUnqual(Type::Int8Ty);
  V = Builder.CreateBitCast(V, PointerType::getUnqual(Ty), "tmp");
  
  Value *Ops[2] = {
    V,
    ConstantPointerNull::get(Ty)
  };
  
  Builder.CreateCall(gcrootFun, Ops, Ops+2);
}  

// Emits annotate intrinsic if the decl has the annotate attribute set.
void TreeToLLVM::EmitAnnotateIntrinsic(Value *V, tree decl) {
  
  // Handle annotate attribute on global.
  tree annotateAttr = lookup_attribute("annotate", DECL_ATTRIBUTES (decl));
  
  if (!annotateAttr)
    return;

  Function *annotateFun = Intrinsic::getDeclaration(TheModule, 
                                                    Intrinsic::var_annotation);

  // Get file and line number
  Constant *lineNo = ConstantInt::get(Type::Int32Ty, DECL_SOURCE_LINE(decl));
  Constant *file = ConvertMetadataStringToGV(DECL_SOURCE_FILE(decl));
  const Type *SBP= PointerType::getUnqual(Type::Int8Ty);
  file = ConstantExpr::getBitCast(file, SBP);
  
  // There may be multiple annotate attributes. Pass return of lookup_attr 
  //  to successive lookups.
  while (annotateAttr) {
    
    // Each annotate attribute is a tree list.
    // Get value of list which is our linked list of args.
    tree args = TREE_VALUE(annotateAttr);
    
    // Each annotate attribute may have multiple args.
    // Treat each arg as if it were a separate annotate attribute.
    for (tree a = args; a; a = TREE_CHAIN(a)) {
      // Each element of the arg list is a tree list, so get value
      tree val = TREE_VALUE(a);
      
      // Assert its a string, and then get that string.
      assert(TREE_CODE(val) == STRING_CST &&
             "Annotate attribute arg should always be a string");
      const Type *SBP = PointerType::getUnqual(Type::Int8Ty);
      Constant *strGV = TreeConstantToLLVM::EmitLV_STRING_CST(val);
      Value *Ops[4] = {
        BitCastToType(V, SBP),
        BitCastToType(strGV, SBP),
        file, 
        lineNo
      };
      
      Builder.CreateCall(annotateFun, Ops, Ops+4);
    }
    
    // Get next annotate attribute.
    annotateAttr = TREE_CHAIN(annotateAttr);
    if (annotateAttr)
      annotateAttr = lookup_attribute("annotate", annotateAttr);
  }
}

//===----------------------------------------------------------------------===//
//                  ... Basic Lists and Binding Scopes ...
//===----------------------------------------------------------------------===//

/// EmitAutomaticVariableDecl - Emit the function-local decl to the current
/// function and set DECL_LLVM for the decl to the right pointer.
void TreeToLLVM::EmitAutomaticVariableDecl(tree decl) {
  tree type = TREE_TYPE(decl);
  
  // An LLVM value pointer for this decl may already be set, for example, if the
  // named return value optimization is being applied to this function, and
  // this variable is the one being returned.
  assert(!DECL_LLVM_SET_P(decl) && "Shouldn't call this on an emitted var!");
  
  // For a CONST_DECL, set mode, alignment, and sizes from those of the
  // type in case this node is used in a reference.
  if (TREE_CODE(decl) == CONST_DECL) {
    DECL_MODE(decl)      = TYPE_MODE(type);
    DECL_ALIGN(decl)     = TYPE_ALIGN(type);
    DECL_SIZE(decl)      = TYPE_SIZE(type);
    DECL_SIZE_UNIT(decl) = TYPE_SIZE_UNIT(type);
    return;
  }
  
  // Otherwise, only automatic (and result) variables need any expansion done.
  // Static and external variables, and external functions, will be handled by
  // `assemble_variable' (called from finish_decl).  TYPE_DECL requires nothing.
  // PARM_DECLs are handled in `llvm_expand_function_start'.
  if ((TREE_CODE(decl) != VAR_DECL && TREE_CODE(decl) != RESULT_DECL) ||
      TREE_STATIC(decl) || DECL_EXTERNAL(decl) || type == error_mark_node)
    return;

  // SSA temporaries are handled specially: their DECL_LLVM is set when the
  // definition is encountered.
  if (isGCC_SSA_Temporary(decl))
    return;
  
  // If this is just the rotten husk of a variable that the gimplifier
  // eliminated all uses of, but is preserving for debug info, ignore it.
  if (TREE_CODE(decl) == VAR_DECL && DECL_VALUE_EXPR(decl))
    return;

  const Type *Ty;  // Type to allocate
  Value *Size = 0; // Amount to alloca (null for 1)

  if (DECL_SIZE(decl) == 0) {    // Variable with incomplete type.
    if (DECL_INITIAL(decl) == 0)
      return; // Error message was already done; now avoid a crash.
    else {
      // "An initializer is going to decide the size of this array."??
      TODO(decl);
      abort();
    }
  } else if (TREE_CODE(DECL_SIZE_UNIT(decl)) == INTEGER_CST) {
    // Variable of fixed size that goes on the stack.
    Ty = ConvertType(type);
  } else {
    tree length;

    // Dynamic-size object: must push space on the stack.
    if (TREE_CODE(type) == ARRAY_TYPE &&
        isSequentialCompatible(type) &&
        (length = arrayLength(type))) {
      Ty = ConvertType(TREE_TYPE(type));  // Get array element type.
      // Compute the number of elements in the array.
      Size = Emit(length, 0);
    } else {
      // Compute the variable's size in bytes.
      Size = Emit(DECL_SIZE_UNIT(decl), 0);
      Ty = Type::Int8Ty;
    }
    Size = CastToUIntType(Size, Type::Int32Ty);
  }

  unsigned Alignment = 0; // Alignment in bytes.

  // Set the alignment for the local if one of the following condition is met
  // 1) DECL_ALIGN_UNIT does not match alignment as per ABI specification
  // 2) DECL_ALIGN is set by user.
  if (DECL_ALIGN_UNIT(decl)) {
    unsigned TargetAlign = getTargetData().getABITypeAlignment(Ty);
    if (DECL_USER_ALIGN(decl) || TargetAlign != (unsigned)DECL_ALIGN_UNIT(decl))
      Alignment = DECL_ALIGN_UNIT(decl);
  }

  const char *Name;      // Name of variable
  if (DECL_NAME(decl))
    Name = IDENTIFIER_POINTER(DECL_NAME(decl));
  else if (TREE_CODE(decl) == RESULT_DECL)
    Name = "retval";
  else
    Name = "tmp";

  // Insert an alloca for this variable.
  AllocaInst *AI;
  if (!Size) {                           // Fixed size alloca -> entry block.
    AI = CreateTemporary(Ty);
    AI->setName(Name);
  } else {
    AI = Builder.CreateAlloca(Ty, Size, Name);
  }
  
  AI->setAlignment(Alignment);
    
  SET_DECL_LLVM(decl, AI);
  
  // Handle annotate attributes
  if (DECL_ATTRIBUTES(decl))
    EmitAnnotateIntrinsic(AI, decl);

  // Handle gcroot attribute
  if (POINTER_TYPE_P(TREE_TYPE (decl))
      && lookup_attribute("gcroot", TYPE_ATTRIBUTES(TREE_TYPE (decl))))
    {
      // We should null out local variables so that a stack crawl
      // before initialization doesn't get garbage results to follow.
      const Type *T = cast<PointerType>(AI->getType())->getElementType();
      EmitTypeGcroot(AI, decl);
      Builder.CreateStore(Constant::getNullValue(T), AI);
    }
  
  if (TheDebugInfo) {
    if (DECL_NAME(decl)) {
      TheDebugInfo->EmitDeclare(decl, llvm::dwarf::DW_TAG_auto_variable,
                                Name, TREE_TYPE(decl), AI,
                                Builder.GetInsertBlock());
    } else if (TREE_CODE(decl) == RESULT_DECL) {
      TheDebugInfo->EmitDeclare(decl, llvm::dwarf::DW_TAG_return_variable,
                                Name, TREE_TYPE(decl), AI,
                                Builder.GetInsertBlock());
    }
  }
}

Value *TreeToLLVM::EmitBIND_EXPR(tree exp, const MemRef *DestLoc) {
  // Start region only if not top level.
  if (TheDebugInfo && DECL_SAVED_TREE(FnDecl) != exp) 
    TheDebugInfo->EmitRegionStart(Fn, Builder.GetInsertBlock());
  
  // Mark the corresponding BLOCK for output in its proper place.
  if (BIND_EXPR_BLOCK(exp) != 0 && !TREE_USED(BIND_EXPR_BLOCK(exp)))
    TREE_USED(BIND_EXPR_BLOCK(exp)) = 1;
  //lang_hooks.decls.insert_block(BIND_EXPR_BLOCK(exp));

  // If VARS have not yet been expanded, expand them now.
  tree Var = BIND_EXPR_VARS(exp);
  for (; Var; Var = TREE_CHAIN(Var)) {
    if (TREE_STATIC(Var)) {
      // If this is an inlined copy of a static local variable, look up the
      // original.
      tree RealVar = DECL_ORIGIN(Var);
      
      // If we haven't already emitted the var, do so now.
      if (!TREE_ASM_WRITTEN(RealVar) && !lang_hooks.expand_decl(RealVar) &&
          TREE_CODE (Var) == VAR_DECL)
        rest_of_decl_compilation(RealVar, 0, 0);
      continue;
    }

    // Otherwise, if this is an automatic variable that hasn't been emitted, do
    // so now.
    if (!DECL_LLVM_SET_P(Var))
      EmitAutomaticVariableDecl(Var);
  }

  // Finally, emit the body of the bind expression.
  Value *Result = Emit(BIND_EXPR_BODY(exp), DestLoc);

  TREE_USED(exp) = 1;

  // End region only if not top level.
  if (TheDebugInfo && DECL_SAVED_TREE(FnDecl) != exp) 
    TheDebugInfo->EmitRegionEnd(Fn, Builder.GetInsertBlock());

  return Result;
}

Value *TreeToLLVM::EmitSTATEMENT_LIST(tree exp, const MemRef *DestLoc) {
  assert(DestLoc == 0 && "Does not return a value!");

  // Convert each statement.
  for (tree_stmt_iterator I = tsi_start(exp); !tsi_end_p(I); tsi_next(&I)) {
    tree stmt = tsi_stmt(I);
    MemRef DestLoc;
    
    // If this stmt returns an aggregate value (e.g. a call whose result is
    // ignored), create a temporary to receive the value.  Note that we don't
    // do this for MODIFY_EXPRs as an efficiency hack.
    if (isAggregateTreeType(TREE_TYPE(stmt)) && TREE_CODE(stmt) != MODIFY_EXPR)
      DestLoc = CreateTempLoc(ConvertType(TREE_TYPE(stmt)));

    Emit(stmt, DestLoc.Ptr ? &DestLoc : NULL);
  }
  return 0;
}

//===----------------------------------------------------------------------===//
//                ... Address Of Labels Extension Support ...
//===----------------------------------------------------------------------===//

/// getIndirectGotoBlockNumber - Return the unique ID of the specified basic
/// block for uses that take the address of it.
Constant *TreeToLLVM::getIndirectGotoBlockNumber(BasicBlock *BB) {
  ConstantInt *&Val = AddressTakenBBNumbers[BB];
  if (Val) return Val;
  
  // Assign the new ID, update AddressTakenBBNumbers to remember it.
  uint64_t BlockNo = ++NumAddressTakenBlocks;
  BlockNo &= ~0ULL >> (64-TD.getPointerSizeInBits());
  Val = ConstantInt::get(TD.getIntPtrType(), BlockNo);

  // Add it to the switch statement in the indirect goto block.
  cast<SwitchInst>(getIndirectGotoBlock()->getTerminator())->addCase(Val, BB);
  return Val;
}

/// getIndirectGotoBlock - Get (and potentially lazily create) the indirect
/// goto block.
BasicBlock *TreeToLLVM::getIndirectGotoBlock() {
  if (IndirectGotoBlock) return IndirectGotoBlock;

  // Create a temporary for the value to be switched on.
  IndirectGotoValue = CreateTemporary(TD.getIntPtrType());
  
  // Create the block, emit a load, and emit the switch in the block.
  IndirectGotoBlock = new BasicBlock("indirectgoto");
  Value *Ld = new LoadInst(IndirectGotoValue, "gotodest", IndirectGotoBlock);
  new SwitchInst(Ld, IndirectGotoBlock, 0, IndirectGotoBlock);
  
  // Finally, return it.
  return IndirectGotoBlock;
}


//===----------------------------------------------------------------------===//
//                           ... Control Flow ...
//===----------------------------------------------------------------------===//

/// getLabelDeclBlock - Lazily get and create a basic block for the specified
/// label.
static BasicBlock *getLabelDeclBlock(tree LabelDecl) {
  assert(TREE_CODE(LabelDecl) == LABEL_DECL && "Isn't a label!?");
  if (DECL_LLVM_SET_P(LabelDecl))
    return cast<BasicBlock>(DECL_LLVM(LabelDecl));

  const char *Name = "bb";
  if (DECL_NAME(LabelDecl))
    Name = IDENTIFIER_POINTER(DECL_NAME(LabelDecl));
  
  BasicBlock *NewBB = new BasicBlock(Name);
  SET_DECL_LLVM(LabelDecl, NewBB);
  return NewBB;
}

/// EmitLABEL_EXPR - Emit the basic block corresponding to the specified label.
///
Value *TreeToLLVM::EmitLABEL_EXPR(tree exp) {
  EmitBlock(getLabelDeclBlock(TREE_OPERAND(exp, 0)));
  return 0;
}

Value *TreeToLLVM::EmitGOTO_EXPR(tree exp) {
  if (TREE_CODE(TREE_OPERAND(exp, 0)) == LABEL_DECL) {
    // Direct branch.
    EmitBranchInternal(getLabelDeclBlock(TREE_OPERAND(exp, 0)), false);
  } else {

    // Otherwise we have an indirect goto.
    BasicBlock *DestBB = getIndirectGotoBlock();

    // Store the destination block to the GotoValue alloca.
    Value *V = Emit(TREE_OPERAND(exp, 0), 0);
    V = CastToType(Instruction::PtrToInt, V, TD.getIntPtrType());
    Builder.CreateStore(V, IndirectGotoValue);
    
    // NOTE: This is HORRIBLY INCORRECT in the presence of exception handlers.
    // There should be one collector block per cleanup level!  Note that
    // standard GCC gets this wrong as well.
    //
    EmitBranchInternal(DestBB, false);
  }
  EmitBlock(new BasicBlock(""));
  return 0;
}


Value *TreeToLLVM::EmitRETURN_EXPR(tree exp, const MemRef *DestLoc) {
  assert(DestLoc == 0 && "Does not return a value!");
  if (TREE_OPERAND(exp, 0)) {
    // Emit the expression, including the assignment to RESULT_DECL.  If the
    // operand is an aggregate value, create a temporary to evaluate it into.
    MemRef DestLoc;
    const Type *DestTy = ConvertType(TREE_TYPE(TREE_OPERAND(exp, 0)));
    if (!DestTy->isFirstClassType() && TREE_CODE(exp) != MODIFY_EXPR)
      DestLoc = CreateTempLoc(DestTy);
    Emit(TREE_OPERAND(exp, 0), DestLoc.Ptr ? &DestLoc : NULL);
  }

  // Emit a branch to the exit label.
  EmitBranchInternal(ReturnBB, false);
  EmitBlock(new BasicBlock(""));
  return 0;
}

Value *TreeToLLVM::EmitCOND_EXPR(tree exp) {
  // Emit the conditional expression.
  Value *Cond = Emit(COND_EXPR_COND(exp), 0);
  // If its not already a bool, insert a comparison against zero to make it so.
  if (Cond->getType() != Type::Int1Ty)
    Cond = Builder.CreateICmpNE(Cond, Constant::getNullValue(Cond->getType()),
                                "toBool");
  tree Then = COND_EXPR_THEN(exp);
  tree Else = COND_EXPR_ELSE(exp);

  // One extremely common pattern produced by the loop lowering code are 
  // COND_EXPRS that look like:
  //
  //    if (cond) { goto <D905>; } else { goto <D907>; }
  //
  // The generic code handles this below, but there is no reason to create a
  // cond branch to two blocks which just contain branches themselves.
  // Note that we only do this if we're not in the presence of C++ exceptions.
  // C++ exceptions could require information for the edge, which requires the
  // uncond branch to be available.
  if (CurrentEHScopes.empty() && TREE_CODE(Then) == STATEMENT_LIST &&
      TREE_CODE(Else) == STATEMENT_LIST) {
    tree_stmt_iterator ThenI = tsi_start(Then), ElseI = tsi_start(Else);
    if (!tsi_end_p(ThenI) && !tsi_end_p(ElseI)) { // {} isn't empty.
      tree ThenStmt = tsi_stmt(ThenI), ElseStmt = tsi_stmt(ElseI);
      tsi_next(&ThenI);
      tsi_next(&ElseI);
      
      if (TREE_CODE(ThenStmt) == GOTO_EXPR &&      // Found two uncond gotos.
          TREE_CODE(ElseStmt) == GOTO_EXPR &&
          tsi_end_p(ThenI) && tsi_end_p(ElseI) &&  // Nothing after them.
          TREE_CODE(TREE_OPERAND(ThenStmt, 0)) == LABEL_DECL &&// Not goto *p.
          TREE_CODE(TREE_OPERAND(ElseStmt, 0)) == LABEL_DECL) {
        BasicBlock *ThenDest = getLabelDeclBlock(TREE_OPERAND(ThenStmt, 0));
        BasicBlock *ElseDest = getLabelDeclBlock(TREE_OPERAND(ElseStmt, 0));
        
        // Okay, we have success. Output the conditional branch.
        Builder.CreateCondBr(Cond, ThenDest, ElseDest);
        // Emit a "fallthrough" block, which is almost certainly dead.
        EmitBlock(new BasicBlock(""));
        return 0;
      }
    }
  }
  
  BasicBlock *TrueBlock = new BasicBlock("cond_true");
  BasicBlock *FalseBlock;
  BasicBlock *ContBlock = new BasicBlock("cond_next");
  
  // Another extremely common case we want to handle are if/then blocks with
  // no else.  The gimplifier turns these into:
  //
  //  if (cond) { goto <D905>; } else { }
  //
  // Recognize when the else is an empty STATEMENT_LIST, and don't emit the
  // else if so.
  //
  bool HasEmptyElse =
    TREE_CODE(Else) == STATEMENT_LIST && tsi_end_p(tsi_start(Else));

  if (HasEmptyElse)
    FalseBlock = ContBlock;
  else
    FalseBlock = new BasicBlock("cond_false");

  // Emit the branch based on the condition.
  Builder.CreateCondBr(Cond, TrueBlock, FalseBlock);
  
  // Emit the true code.
  EmitBlock(TrueBlock);
  
  Emit(Then, 0);
  
  // If this is an if/then/else cond-expr, emit the else part, otherwise, just
  // fall through to the ContBlock.
  if (!HasEmptyElse) {
    if (Builder.GetInsertBlock()->getTerminator() == 0 &&
        (!Builder.GetInsertBlock()->getName().empty() || 
         !Builder.GetInsertBlock()->use_empty()))
      Builder.CreateBr(ContBlock);  // Branch to continue block.

    EmitBlock(FalseBlock);
    
    Emit(Else, 0);
  }
  
  EmitBlock(ContBlock);
  return 0;
}

Value *TreeToLLVM::EmitSWITCH_EXPR(tree exp) {
  tree Cases = SWITCH_LABELS(exp);
  
  // Emit the condition.
  Value *SwitchExp = Emit(SWITCH_COND(exp), 0);
  bool ExpIsSigned = !TYPE_UNSIGNED(TREE_TYPE(SWITCH_COND(exp)));
  
  // Emit the switch instruction.
  SwitchInst *SI = Builder.CreateSwitch(SwitchExp, Builder.GetInsertBlock(),
                                        TREE_VEC_LENGTH(Cases));
  EmitBlock(new BasicBlock(""));
  // Default location starts out as fall-through
  SI->setSuccessor(0, Builder.GetInsertBlock());

  assert(!SWITCH_BODY(exp) && "not a gimple switch?");

  BasicBlock *DefaultDest = NULL;
  for (unsigned i = 0, e = TREE_VEC_LENGTH(Cases); i != e; ++i) {
    BasicBlock *Dest = getLabelDeclBlock(CASE_LABEL(TREE_VEC_ELT(Cases, i)));

    tree low = CASE_LOW(TREE_VEC_ELT(Cases, i));
    if (!low) {
      DefaultDest = Dest;
      continue;
    }

    // Convert the integer to the right type.
    Value *Val = Emit(low, 0);
    Val = CastToAnyType(Val, !TYPE_UNSIGNED(TREE_TYPE(low)),
                        SwitchExp->getType(), ExpIsSigned);
    ConstantInt *LowC = cast<ConstantInt>(Val);

    tree high = CASE_HIGH(TREE_VEC_ELT(Cases, i));
    if (!high) {
      SI->addCase(LowC, Dest); // Single destination.
      continue;
    }

    // Otherwise, we have a range, like 'case 1 ... 17'.
    Val = Emit(high, 0);
    // Make sure the case value is the same type as the switch expression
    Val = CastToAnyType(Val, !TYPE_UNSIGNED(TREE_TYPE(high)),
                        SwitchExp->getType(), ExpIsSigned);
    ConstantInt *HighC = cast<ConstantInt>(Val);

    APInt Range = HighC->getValue() - LowC->getValue();
    if (Range.ult(APInt(Range.getBitWidth(), 64))) {
      // Add all of the necessary successors to the switch.
      APInt CurrentValue = LowC->getValue();
      while (1) {
        SI->addCase(LowC, Dest);
        if (LowC == HighC) break;  // Emitted the last one.
        CurrentValue++;
        LowC = ConstantInt::get(CurrentValue);
      }
    } else {
      // The range is too big to add to the switch - emit an "if".
      Value *Diff = Builder.CreateSub(SwitchExp, LowC, "tmp");
      Value *Cond = Builder.CreateICmpULE(Diff, ConstantInt::get(Range), "tmp");
      BasicBlock *False_Block = new BasicBlock("case_false");
      Builder.CreateCondBr(Cond, Dest, False_Block);
      EmitBlock(False_Block);
    }
  }

  if (DefaultDest)
    if (SI->getSuccessor(0) == Builder.GetInsertBlock())
      SI->setSuccessor(0, DefaultDest);
    else {
      Builder.CreateBr(DefaultDest);
      // Emit a "fallthrough" block, which is almost certainly dead.
      EmitBlock(new BasicBlock(""));
    }

  return 0;
}

#ifndef NDEBUG
void TreeToLLVM::dumpEHScopes() const {
  std::cerr << CurrentEHScopes.size() << " EH Scopes:\n";
  for (unsigned i = 0, e = CurrentEHScopes.size(); i != e; ++i) {
    std::cerr << "  " << i << ". catch=" << (void*)CurrentEHScopes[i].CatchExpr
              << " #blocks=" << CurrentEHScopes[i].Blocks.size()
              << " #fixups=" << CurrentEHScopes[i].BranchFixups.size() << "\n";
    for (unsigned f = 0, e = CurrentEHScopes[i].BranchFixups.size(); f != e;++f)
      std::cerr << "    Fixup #" << f << ": isEH="
                << CurrentEHScopes[i].BranchFixups[f].isExceptionEdge
                << "  br = " << *CurrentEHScopes[i].BranchFixups[f].SrcBranch;
  }
}
#endif

/// StripLLVMTranslationFn - Recursive function called from walk_trees to
/// implement StripLLVMTranslation.
static tree StripLLVMTranslationFn(tree *nodep, int *walk_subtrees,
                                   void *data) {
  tree node = *nodep;
  if (TYPE_P(node)) {
    // Don't walk into types.
    *walk_subtrees = 0;
  } else if (TREE_CODE(node) == STATEMENT_LIST) {
    // Look for basic block labels, clearing them out.
    for (tree_stmt_iterator I = tsi_start(node); !tsi_end_p(I); tsi_next(&I))
      if (TREE_CODE(tsi_stmt(I)) == LABEL_EXPR)
        SET_DECL_LLVM(TREE_OPERAND(tsi_stmt(I), 0), 0);
  } else if (TREE_CODE(node) == BIND_EXPR) {
    // Reset the declarations for local vars.  
    tree Var = BIND_EXPR_VARS(node);
    for (; Var; Var = TREE_CHAIN(Var)) {
      if (TREE_CODE(Var) == VAR_DECL && !TREE_STATIC(Var))
        SET_DECL_LLVM(Var, 0);
    }
  }
  return NULL_TREE;
}


/// StripLLVMTranslation - Given a block of code, walk it stripping off LLVM
/// information from declarations.  This permits the code to be expanded into
/// multiple places in the code without (e.g.) emitting the same LABEL_DECL node
/// into multiple places.
static void StripLLVMTranslation(tree code) {
  // Strip off llvm code.
  walk_tree_without_duplicates(&code, StripLLVMTranslationFn, 0);
}


/// GatherTypeInfo - Walk through the expression gathering all the
/// typeinfos that are used.
void TreeToLLVM::GatherTypeInfo(tree exp,
                                std::vector<Constant *> &TypeInfos) {
  if (TREE_CODE(exp) == CATCH_EXPR || TREE_CODE(exp) == EH_FILTER_EXPR) {
    tree Types = TREE_CODE(exp) == CATCH_EXPR ? CATCH_TYPES(exp)
                                              : EH_FILTER_TYPES(exp);

    if (!Types) {
      // Catch all or empty filter.
      if (TREE_CODE(exp) == CATCH_EXPR)
        // Catch all.
        TypeInfos.push_back(
          Constant::getNullValue(PointerType::getUnqual(Type::Int8Ty))
        );
    } else if (TREE_CODE(Types) != TREE_LIST) {
      // Construct typeinfo object.  Each call will produce a new expression
      // even if duplicate.
      tree TypeInfoNopExpr = (*lang_eh_runtime_type)(Types);
      // Produce value.  Duplicate typeinfo get folded here.
      Value *TypeInfo = Emit(TypeInfoNopExpr, 0);
      // Capture typeinfo.
      TypeInfos.push_back(cast<Constant>(TypeInfo));
    } else {
      for (; Types; Types = TREE_CHAIN (Types)) {
        // Construct typeinfo object.  Each call will produce a new expression
        // even if duplicate.
        tree TypeInfoNopExpr = (*lang_eh_runtime_type)(TREE_VALUE(Types));
        // Produce value.  Duplicate typeinfo get folded here.
        Value *TypeInfo = Emit(TypeInfoNopExpr, 0);
        // Capture typeinfo.
        TypeInfos.push_back(cast<Constant>(TypeInfo));
      }
    }
  } else if (TREE_CODE(exp) == STATEMENT_LIST) {
    // Each statement in the statement list will be a catch, or none will.
    for (tree_stmt_iterator I = tsi_start(exp); !tsi_end_p(I); tsi_next(&I))
      GatherTypeInfo(tsi_stmt(I), TypeInfos);
  } else {
    assert(TypeInfos.empty() && "Need an exp with typeinfo");
  }
}


/// AddLandingPad - Insert code to fetch and save the exception and exception
/// selector.
void TreeToLLVM::AddLandingPad() {
  CreateExceptionValues();

  // Fetch and store the exception.
  Value *Ex = Builder.CreateCall(FuncEHException, "eh_ptr");
  Builder.CreateStore(Ex, ExceptionValue);

  // Fetch and store the exception selector.
  std::vector<Value*> Args;

  // The exception and the personality function.
  Args.push_back(Builder.CreateLoad(ExceptionValue, "eh_ptr"));
  Args.push_back(CastToType(Instruction::BitCast, FuncCPPPersonality,
                            PointerType::getUnqual(Type::Int8Ty)));

  bool CaughtAll = false;
  for (std::vector<EHScope>::reverse_iterator I = CurrentEHScopes.rbegin(),
       E = CurrentEHScopes.rend(); I != E; ++I) {
    if (I->CatchExpr) {
      if (I->InfosType == Unknown) {
         // Gather the type info and determine the catch type.
         GatherTypeInfo(I->CatchExpr, I->TypeInfos);
         I->InfosType = (TREE_CODE(I->CatchExpr) == STATEMENT_LIST &&
                         !tsi_end_p(tsi_start(I->CatchExpr)) &&
                         TREE_CODE(tsi_stmt(tsi_start(I->CatchExpr))) ==
                         EH_FILTER_EXPR) ? FilterExpr : CatchList;
      }

      if (I->InfosType == FilterExpr) {
        // Filter - note the size.
        Args.push_back(ConstantInt::get(Type::Int32Ty, I->TypeInfos.size()+1));
        // An empty filter catches all exceptions.
        if ((CaughtAll = !I->TypeInfos.size()))
          break;
      }

      Args.reserve(Args.size() + I->TypeInfos.size());
      for (unsigned j = 0, N = I->TypeInfos.size(); j < N; ++j) {
        Args.push_back(I->TypeInfos[j]);
        // A null typeinfo indicates a catch-all.
        if ((CaughtAll = I->TypeInfos[j]->isNullValue()))
          break;
      }
    }
  }

  // Invokes are required to branch to the unwind label no matter what exception
  // is being unwound.  Enforce this by appending a catch-all.
  // FIXME: The use of null as catch-all is C++ specific.
  if (!CaughtAll)
    Args.push_back(
      Constant::getNullValue(PointerType::getUnqual(Type::Int8Ty)));

  Value *Select = Builder.CreateCall(FuncEHSelector, Args.begin(), Args.end(),
                                     "eh_select");
  Builder.CreateStore(Select, ExceptionSelectorValue);
}


/// CreateExceptionValues - Create values used internally by exception handling.
///
void TreeToLLVM::CreateExceptionValues() {
  // Check to see if the exception values have been constructed.
  if (ExceptionValue) return;

  const Type *IntPtr = TD.getIntPtrType();
  
  ExceptionValue = CreateTemporary(PointerType::getUnqual(Type::Int8Ty));
  ExceptionValue->setName("eh_exception");
  
  ExceptionSelectorValue = CreateTemporary(IntPtr);
  ExceptionSelectorValue->setName("eh_selector");
  
  FuncEHException = Intrinsic::getDeclaration(TheModule,
                                              Intrinsic::eh_exception);
  FuncEHSelector  = Intrinsic::getDeclaration(TheModule,
                                              (IntPtr == Type::Int32Ty ?
                                               Intrinsic::eh_selector_i32 :
                                               Intrinsic::eh_selector_i64));
  FuncEHGetTypeID = Intrinsic::getDeclaration(TheModule,
                                              (IntPtr == Type::Int32Ty ?
                                               Intrinsic::eh_typeid_for_i32 :
                                               Intrinsic::eh_typeid_for_i64));
                                                      
  FuncCPPPersonality =
    TheModule->getOrInsertFunction("__gxx_personality_v0",
                                   Type::getPrimitiveType(Type::VoidTyID),
                                   NULL);

  FuncUnwindResume =
    TheModule->getOrInsertFunction(
#ifdef LLVM_STACKSENSITIVE_UNWIND_RESUME
                                   "_Unwind_Resume_or_Rethrow",
#else
                                   "_Unwind_Resume",
#endif
                                   Type::getPrimitiveType(Type::VoidTyID),
                                   PointerType::getUnqual(Type::Int8Ty),
                                   NULL);

}


/// EmitProtectedCleanups - Wrap cleanups in a TRY_FILTER_EXPR that executes the
/// code specified by lang_protect_cleanup_actions if an exception is thrown.
void TreeToLLVM::EmitProtectedCleanups(tree cleanups) {
  if (!lang_protect_cleanup_actions) {
    Emit(cleanups, 0);
    return;
  }

  if (CleanupFilter == NULL_TREE) {
    // Create a catch-all filter that routes exceptions to the code specified
    // by the lang_protect_cleanup_actions langhook.
    // FIXME: the handler is supposed to be a "nothrow region".  Support for
    // this is blocked on support for nothrow functions.
    tree filter = build (EH_FILTER_EXPR, void_type_node, NULL, NULL);
    append_to_statement_list (lang_protect_cleanup_actions(),
                              &EH_FILTER_FAILURE (filter));
    // CleanupFilter is the filter wrapped in a STATEMENT_LIST.
    append_to_statement_list (filter, &CleanupFilter);
  }

  EmitTryInternal(cleanups, CleanupFilter, true);
}


/// EmitTRY_EXPR - Handle TRY_FINALLY_EXPR and TRY_CATCH_EXPR.
Value *TreeToLLVM::EmitTRY_EXPR(tree exp) {
  return EmitTryInternal(TREE_OPERAND(exp, 0), TREE_OPERAND(exp, 1),
                         TREE_CODE(exp) == TRY_CATCH_EXPR);
}


/// EmitTryInternal - Handle TRY_FINALLY_EXPR and TRY_CATCH_EXPR given only the
/// expression operands.  Done to avoid having EmitProtectedCleanups build a new
/// TRY_CATCH_EXPR for every cleanup block it wraps.
Value *TreeToLLVM::EmitTryInternal(tree inner, tree handler, bool isCatch) {
  // The C++ front-end produces a lot of TRY_FINALLY_EXPR nodes that have empty
  // try blocks.  When these are seen, just emit the finally block directly for
  // a small compile time speedup.
  if (TREE_CODE(inner) == STATEMENT_LIST && tsi_end_p(tsi_start(inner))) {
    if (isCatch)
      return 0;   // TRY_CATCH_EXPR with empty try block: nothing thrown.

    // TRY_FINALLY_EXPR - Just run the finally block.
    assert(!isCatch);
    EmitProtectedCleanups(handler);
    return 0;
  }  

  // Remember that we are in this scope.
  CurrentEHScopes.push_back(isCatch ? handler : NULL);
  
  Emit(inner, 0);
  
  assert(!isCatch || CurrentEHScopes.back().CatchExpr == handler
         && "Scope imbalance!");

  // Emit a new block for the fall-through of the finally block.
  BasicBlock *FinallyBlock = new BasicBlock("finally");
  EmitBlock(FinallyBlock);

  // Get the basic blocks in the current scope.
  std::vector<BasicBlock*> BlocksInScope;
  std::swap(CurrentEHScopes.back().Blocks, BlocksInScope);
  
  // Get the fixups in the current scope.
  std::vector<BranchFixup> BranchFixups;
  std::swap(CurrentEHScopes.back().BranchFixups, BranchFixups);
  
  // Remove the current scope.  The state of the function is no longer in this
  // scope.
  CurrentEHScopes.pop_back();

  // The finally fall-through block actually goes into the parent EH scope.  We
  // must emit things in this order so that EmitBlock can choose to nuke the
  // previous block, and correctly nuke it from the nested scope.
  if (!CurrentEHScopes.empty()) {
    CurrentEHScopes.back().Blocks.push_back(FinallyBlock);
    BlockEHScope[FinallyBlock] = CurrentEHScopes.size()-1;
  } else {
    BlockEHScope.erase(FinallyBlock);
  }
  
  // The finally block is not in the inner scope, it's actually in the outer
  // one.
  assert(BlocksInScope.back() == FinallyBlock);
  BlocksInScope.pop_back();
  
  // Give the FinallyBlock back a temporary terminator instruction.
  new UnreachableInst(FinallyBlock);

  // If the try block falls through (i.e. it doesn't end with a return), make
  // sure to add a fixup on that edge if needed.  If it falls through, EmitBlock
  // would add a branch from the fall-through source to FinallyBlock, otherwise
  // there will be no uses of it.
  if (!FinallyBlock->use_empty()) {
    BranchInst *BI = cast<BranchInst>(FinallyBlock->use_back());
    assert(FinallyBlock->hasOneUse() && BI->isUnconditional() &&
           "Unexpected behavior for EmitBlock");
    // Add an extra branch fixup for the try fall-through.
    BranchFixups.push_back(BranchFixup(BI, false));
  }
  
  // Loop over all of the fixups.  If the fixup destination was in the current
  // scope, then there is nothing to do and the fixup is done.  Remove these.
  for (unsigned i = 0, e = BranchFixups.size(); i != e; ++i) {
    BasicBlock *DestBlock = BranchFixups[i].SrcBranch->getSuccessor(0);
    std::map<BasicBlock*, unsigned>::iterator I = BlockEHScope.find(DestBlock);
    if (I != BlockEHScope.end() && I->second == CurrentEHScopes.size()) {
      BranchFixups[i] = BranchFixups.back();
      BranchFixups.pop_back();
      --i; --e;
      continue;
    }
    
    // If this is a TRY_CATCH expression and the fixup isn't for an exception
    // edge, punt the fixup up to the parent scope.
    if (isCatch && !BranchFixups[i].isExceptionEdge) {
      // Add the fixup to the parent cleanup scope if there is one.
      if (!CurrentEHScopes.empty())
        AddBranchFixup(BranchFixups[i].SrcBranch, false);
      // Remove the fixup from this scope.
      BranchFixups[i] = BranchFixups.back();
      BranchFixups.pop_back();
      --i; --e;
      continue;
    }
  }
  
  // Otherwise, the branch is to some block outside of the scope, which requires
  // us to emit a copy of the finally code into the codepath.
  while (!BranchFixups.empty()) {
    BranchInst *FixupBr = BranchFixups.back().SrcBranch;
    bool FixupIsExceptionEdge = BranchFixups.back().isExceptionEdge;
    BranchFixups.pop_back();
    
    // Okay, the destination is in a parent to this scope, which means that the
    // branch fixup corresponds to an exit from this region.  Expand the cleanup
    // code then patch it into the code sequence.

    // Add a basic block to emit the code into.
    BasicBlock *CleanupBB = new BasicBlock("cleanup");
    EmitBlock(CleanupBB);
    
    // Provide exit point for cleanup code.
    FinallyStack.push_back(FinallyBlock);

    // Emit the code.
    if (isCatch)
      switch (TREE_CODE (tsi_stmt (tsi_start (handler)))) {
      case CATCH_EXPR:
      case EH_FILTER_EXPR:
        Emit(handler, 0);
        break;
      default:
        // Wrap the handler in a filter, like for TRY_FINALLY_EXPR, since this
        // is what tree-eh.c does.
        EmitProtectedCleanups(handler);
        break;
      }
    else
      EmitProtectedCleanups(handler);

    // Clear exit point for cleanup code.
    FinallyStack.pop_back();

    // Because we can emit the same cleanup in more than one context, we must
    // strip off LLVM information from the decls in the code.  Otherwise, we
    // will try to insert the same label into multiple places in the code.
    StripLLVMTranslation(handler);


    // Catches will supply own terminator.
    if (!Builder.GetInsertBlock()->getTerminator()) {
      // Emit a branch to the new target.
      BranchInst *BI = Builder.CreateBr(FixupBr->getSuccessor(0));
    
      // The old branch now goes to the cleanup block.
      FixupBr->setSuccessor(0, CleanupBB);
    
      // Fixup this new branch now.
      FixupBr = BI;
      
      // Add the fixup to the next cleanup scope if there is one.
      if (!CurrentEHScopes.empty())
        AddBranchFixup(FixupBr, FixupIsExceptionEdge);
    } else {
      // The old branch now goes to the cleanup block.
      FixupBr->setSuccessor(0, CleanupBB);
    }
  }

  // Move the finally block to the end of the function so we can continue
  // emitting code into it.
  Fn->getBasicBlockList().splice(Fn->end(), Fn->getBasicBlockList(),
                                 FinallyBlock);
  Builder.SetInsertPoint(FinallyBlock);
  
  // Now that all of the cleanup blocks have been expanded, remove the temporary
  // terminator we put on the FinallyBlock.
  assert(isa<UnreachableInst>(FinallyBlock->getTerminator()));
  FinallyBlock->getInstList().pop_back();
  
  // Finally, remove the blocks in the scope from the BlockEHScope map.
  for (unsigned i = 0, e = BlocksInScope.size(); i != e; ++i) {
    bool Erased = BlockEHScope.erase(BlocksInScope[i]);
    assert(Erased && "Block wasn't in map!");
  }
  return 0;
}


/// EmitCATCH_EXPR - Handle CATCH_EXPR.
///
Value *TreeToLLVM::EmitCATCH_EXPR(tree exp) {
#ifndef ITANIUM_STYLE_EXCEPTIONS
  return 0;
#endif

  // Make sure we have all the exception values in place.
  CreateExceptionValues();

  // Break out parts of catch.
  tree Types = CATCH_TYPES(exp);
  tree Body = CATCH_BODY(exp);
  
  // Destinations of the catch entry conditions.
  BasicBlock *ThenBlock = 0;
  BasicBlock *ElseBlock = 0;
  
  // FiXME - Determine last case so we don't need to emit test.
  if (!Types) {
    // Catch all - no testing required.
  } else if (TREE_CODE(Types) != TREE_LIST) {
    // Construct typeinfo object.  Each call will produce a new expression
    // even if duplicate.
    tree TypeInfoNopExpr = (*lang_eh_runtime_type)(Types);
    // Produce value.  Duplicate typeinfo get folded here.
    Value *TypeInfo = Emit(TypeInfoNopExpr, 0);
    TypeInfo = BitCastToType(TypeInfo, PointerType::getUnqual(Type::Int8Ty));

    // Call get eh type id.
    Value *TypeID = Builder.CreateCall(FuncEHGetTypeID, TypeInfo,
                                       "eh_typeid");
    Value *Select = Builder.CreateLoad(ExceptionSelectorValue, "tmp");

    // Compare with the exception selector.
    Value *Compare = Builder.CreateICmpEQ(Select, TypeID, "tmp");
    ThenBlock = new BasicBlock("eh_then");
    ElseBlock = new BasicBlock("eh_else");
    
    // Branch on the compare.
    Builder.CreateCondBr(Compare, ThenBlock, ElseBlock);
  } else {
    ThenBlock = new BasicBlock("eh_then");
  
    for (; Types; Types = TREE_CHAIN (Types)) {
      if (ElseBlock) EmitBlock(ElseBlock);
    
      // Construct typeinfo object.  Each call will produce a new expression
      // even if duplicate.
      tree TypeInfoNopExpr = (*lang_eh_runtime_type)(TREE_VALUE(Types));
      // Produce value.  Duplicate typeinfo get folded here.
      Value *TypeInfo = Emit(TypeInfoNopExpr, 0);
      TypeInfo = BitCastToType(TypeInfo, PointerType::getUnqual(Type::Int8Ty));

      // Call get eh type id.
      Value *TypeID = Builder.CreateCall(FuncEHGetTypeID, TypeInfo,
                                         "eh_typeid");
      Value *Select = Builder.CreateLoad(ExceptionSelectorValue, "tmp");

      // Compare with the exception selector.
      Value *Compare = Builder.CreateICmpEQ(Select, TypeID, "tmp");
      ElseBlock = new BasicBlock("eh_else");
      
      // Branch on the compare.
      Builder.CreateCondBr(Compare, ThenBlock, ElseBlock);
    }
  }
  
  // Start the then block.
  if (ThenBlock) EmitBlock(ThenBlock);
  
  // Emit the body.
  Emit(Body, 0);

  // Branch to the try exit.
  assert(!FinallyStack.empty() && "Need an exit point");
  if (!Builder.GetInsertBlock()->getTerminator())
    Builder.CreateBr(FinallyStack.back());

  // Start the else block.
  if (ElseBlock) EmitBlock(ElseBlock);
  
  return 0;
}

/// EmitEXC_PTR_EXPR - Handle EXC_PTR_EXPR.
///
Value *TreeToLLVM::EmitEXC_PTR_EXPR(tree exp) {
#ifndef ITANIUM_STYLE_EXCEPTIONS
  return 0;
#endif

  // Load exception address.
  CreateExceptionValues();
  return Builder.CreateLoad(ExceptionValue, "eh_value");
}

/// EmitEH_FILTER_EXPR - Handle EH_FILTER_EXPR.
///
Value *TreeToLLVM::EmitEH_FILTER_EXPR(tree exp) {
#ifndef ITANIUM_STYLE_EXCEPTIONS
  return 0;
#endif

  CreateExceptionValues();

  // The result of a filter landing pad will be a negative index if there is
  // a match.
  Value *Select = Builder.CreateLoad(ExceptionSelectorValue, "tmp");

  // Compare with the filter action value.
  Value *Zero = ConstantInt::get(Select->getType(), 0);
  Value *Compare = Builder.CreateICmpSLT(Select, Zero, "tmp");
  
  // Branch on the compare.
  BasicBlock *FilterBB = new BasicBlock("filter");
  BasicBlock *NoFilterBB = new BasicBlock("nofilter");
  Builder.CreateCondBr(Compare, FilterBB, NoFilterBB);

  EmitBlock(FilterBB);
  Emit(EH_FILTER_FAILURE(exp), 0);
  
  EmitBlock(NoFilterBB);
  
  return 0;
}

//===----------------------------------------------------------------------===//
//                           ... Expressions ...
//===----------------------------------------------------------------------===//

/// EmitINTEGER_CST_Aggregate - The C++ front-end abuses INTEGER_CST nodes to
/// represent empty classes.  For now we check that this is the case we handle,
/// then zero out DestLoc.
///
/// FIXME: When merged with mainline, remove this code.  The C++ front-end has
/// been fixed.
///
void TreeToLLVM::EmitINTEGER_CST_Aggregate(tree exp, const MemRef *DestLoc) {
  tree type = TREE_TYPE(exp);
#ifndef NDEBUG
  assert(TREE_CODE(type) == RECORD_TYPE && "Not an empty class!");
  for (tree F = TYPE_FIELDS(type); F; F = TREE_CHAIN(F))
    assert(TREE_CODE(F) != FIELD_DECL && "Not an empty struct/class!");
#endif
  EmitAggregateZero(*DestLoc, type);
}

/// EmitLoadOfLValue - When an l-value expression is used in a context that
/// requires an r-value, this method emits the lvalue computation, then loads
/// the result.
Value *TreeToLLVM::EmitLoadOfLValue(tree exp, const MemRef *DestLoc) {
  // If this is an SSA value, don't emit a load, just use the result.
  if (isGCC_SSA_Temporary(exp)) {
    assert(DECL_LLVM_SET_P(exp) && "Definition not found before use!");
    return DECL_LLVM(exp);
  } else if (TREE_CODE(exp) == VAR_DECL && DECL_REGISTER(exp) &&
             TREE_STATIC(exp)) {
    // If this is a register variable, EmitLV can't handle it (there is no
    // l-value of a register variable).  Emit an inline asm node that copies the
    // value out of the specified register.
    return EmitReadOfRegisterVariable(exp, DestLoc);
  }
  
  LValue LV = EmitLV(exp);
  bool isVolatile = TREE_THIS_VOLATILE(exp);
  const Type *Ty = ConvertType(TREE_TYPE(exp));
  unsigned Alignment = expr_align(exp) / 8;
  
  if (!LV.isBitfield()) {
    if (!DestLoc) {
      // Scalar value: emit a load.
      Value *Ptr = CastToType(Instruction::BitCast, LV.Ptr, 
                              PointerType::getUnqual(Ty));
      LoadInst *LI = Builder.CreateLoad(Ptr, isVolatile, "tmp");
      LI->setAlignment(Alignment);
      return LI;
    } else {
      EmitAggregateCopy(*DestLoc, MemRef(LV.Ptr, Alignment, isVolatile),
                        TREE_TYPE(exp));
      return 0;
    }
  } else {
    // This is a bitfield reference.
    if (!LV.BitSize)
      return Constant::getNullValue(Ty);

    const Type *ValTy = cast<PointerType>(LV.Ptr->getType())->getElementType();
    unsigned ValSizeInBits = ValTy->getPrimitiveSizeInBits();

    // The number of loads needed to read the entire bitfield.
    unsigned Strides = 1 + (LV.BitStart + LV.BitSize - 1) / ValSizeInBits;

    assert(ValTy->isInteger() && "Invalid bitfield lvalue!");
    assert(ValSizeInBits > LV.BitStart && "Bad bitfield lvalue!");
    assert(ValSizeInBits >= LV.BitSize && "Bad bitfield lvalue!");
    assert(2*ValSizeInBits > LV.BitSize+LV.BitStart && "Bad bitfield lvalue!");

    Value *Result = NULL;

    for (unsigned I = 0; I < Strides; I++) {
      unsigned Index = BYTES_BIG_ENDIAN ? I : Strides - I - 1; // MSB first
      unsigned ThisFirstBit = Index * ValSizeInBits;
      unsigned ThisLastBitPlusOne = ThisFirstBit + ValSizeInBits;
      if (ThisFirstBit < LV.BitStart)
        ThisFirstBit = LV.BitStart;
      if (ThisLastBitPlusOne > LV.BitStart+LV.BitSize)
        ThisLastBitPlusOne = LV.BitStart+LV.BitSize;

      Value *Ptr = Index ?
        Builder.CreateGEP(LV.Ptr, ConstantInt::get(Type::Int32Ty, Index),
                          "tmp") : LV.Ptr;
      LoadInst *LI = Builder.CreateLoad(Ptr, isVolatile, "tmp");
      LI->setAlignment(Alignment);
      Value *Val = LI;

      unsigned BitsInVal = ThisLastBitPlusOne - ThisFirstBit;
      unsigned FirstBitInVal = ThisFirstBit % ValSizeInBits;

      // If this target has bitfields laid out in big-endian order, invert the bit
      // in the word if needed.
      if (BITS_BIG_ENDIAN)
        FirstBitInVal = ValSizeInBits-FirstBitInVal-BitsInVal;

      // Mask the bits out by shifting left first, then shifting right.  The
      // LLVM optimizer will turn this into an AND if this is an unsigned
      // expression.

      if (FirstBitInVal+BitsInVal != ValSizeInBits) {
        Value *ShAmt = ConstantInt::get(ValTy,
                                        ValSizeInBits-(FirstBitInVal+BitsInVal));
        Val = Builder.CreateShl(Val, ShAmt, "tmp");
      }

      // Shift right required?
      if (ValSizeInBits != BitsInVal) {
        bool AddSignBits = !TYPE_UNSIGNED(TREE_TYPE(exp)) && !Result;
        Value *ShAmt = ConstantInt::get(ValTy, ValSizeInBits-BitsInVal);
        Val = AddSignBits ?
          Builder.CreateAShr(Val, ShAmt, "tmp") :
          Builder.CreateLShr(Val, ShAmt, "tmp");
      }

      if (Result) {
        Value *ShAmt = ConstantInt::get(ValTy, BitsInVal);
        Result = Builder.CreateShl(Result, ShAmt, "tmp");
        Result = Builder.CreateOr(Result, Val, "tmp");
      } else {
        Result = Val;
      }
    }

    if (TYPE_UNSIGNED(TREE_TYPE(exp)))
      return CastToUIntType(Result, Ty);
    else
      return CastToSIntType(Result, Ty);
  }
}

Value *TreeToLLVM::EmitADDR_EXPR(tree exp) {
  LValue LV = EmitLV(TREE_OPERAND(exp, 0));
  assert((!LV.isBitfield() || LV.BitStart == 0) &&
         "It is illegal to take the address of a bitfield");
  // Perform a cast here if necessary.  For example, GCC sometimes forms an
  // ADDR_EXPR where the operand is an array, and the ADDR_EXPR type is a
  // pointer to the first element.
  return CastToType(Instruction::BitCast, LV.Ptr, ConvertType(TREE_TYPE(exp))); 
}

Value *TreeToLLVM::EmitOBJ_TYPE_REF(tree exp) {
  return CastToType(Instruction::BitCast, Emit(OBJ_TYPE_REF_EXPR(exp), 0), 
                    ConvertType(TREE_TYPE(exp))); 
}

Value *TreeToLLVM::EmitCALL_EXPR(tree exp, const MemRef *DestLoc) {
  // Check for a built-in function call.  If we can lower it directly, do so
  // now.
  tree fndecl = get_callee_fndecl(exp);
  if (fndecl && DECL_BUILT_IN(fndecl) &&
      DECL_BUILT_IN_CLASS(fndecl) != BUILT_IN_FRONTEND) {
    Value *Res = 0;
    if (EmitBuiltinCall(exp, fndecl, DestLoc, Res))
      return Res;
  }

  Value *Callee = Emit(TREE_OPERAND(exp, 0), 0);

  assert(TREE_TYPE (TREE_OPERAND (exp, 0)) &&
         TREE_CODE(TREE_TYPE (TREE_OPERAND (exp, 0))) == POINTER_TYPE
         && "Not calling a function pointer?");
  tree function_type = TREE_TYPE(TREE_TYPE (TREE_OPERAND (exp, 0)));
  unsigned CallingConv;
  PAListPtr PAL;

  const Type *Ty = TheTypeConverter->ConvertFunctionType(function_type,
                                                         fndecl,
                                                         TREE_OPERAND(exp, 2),
                                                         CallingConv, PAL);

  // If this is a direct call to a function using a static chain then we need
  // to ensure the function type is the one just calculated: it has an extra
  // parameter for the chain.
  Callee = BitCastToType(Callee, PointerType::getUnqual(Ty));

  //EmitCall(exp, DestLoc);
  Value *Result = EmitCallOf(Callee, exp, DestLoc, PAL);

  // If the function has the volatile bit set, then it is a "noreturn" function.
  // Output an unreachable instruction right after the function to prevent LLVM
  // from thinking that control flow will fall into the subsequent block.
  //
  if (fndecl && TREE_THIS_VOLATILE(fndecl)) {
    Builder.CreateUnreachable();
    EmitBlock(new BasicBlock(""));
  }
  return Result;
}

namespace {
  /// FunctionCallArgumentConversion - This helper class is driven by the ABI
  /// definition for this target to figure out how to pass arguments into the
  /// stack/regs for a function call.
  struct FunctionCallArgumentConversion : public DefaultABIClient {
    tree CallExpression;
    SmallVector<Value*, 16> &CallOperands;
    CallingConv::ID &CallingConvention;
    LLVMBuilder &Builder;
    const MemRef *DestLoc;
    std::vector<Value*> LocStack;

    FunctionCallArgumentConversion(tree exp, SmallVector<Value*, 16> &ops,
                                   CallingConv::ID &cc,
                                   LLVMBuilder &b, const MemRef *destloc)
      : CallExpression(exp), CallOperands(ops), CallingConvention(cc),
        Builder(b), DestLoc(destloc) {
      CallingConvention = CallingConv::C;
#ifdef TARGET_ADJUST_LLVM_CC
      tree ftype;
      if (tree fdecl = get_callee_fndecl(exp)) {
        ftype = TREE_TYPE(fdecl);
      } else {
        ftype = TREE_TYPE(TREE_OPERAND(exp,0));

        // If it's call to pointer, we look for the function type.
        if (TREE_CODE(ftype) == POINTER_TYPE)
          ftype = TREE_TYPE(ftype);
      }
      
      TARGET_ADJUST_LLVM_CC(CallingConvention, ftype);
#endif
    }
    
    void setLocation(Value *Loc) {
      LocStack.push_back(Loc);
    }
    void clear() {
      assert(LocStack.size() == 1 && "Imbalance!");
      LocStack.clear();
    }
    
    /// HandleScalarResult - This callback is invoked if the function returns a
    /// simple scalar result value.
    void HandleScalarResult(const Type *RetTy) {
      // There is nothing to do here if we return a scalar or void.
      assert(DestLoc == 0 &&
             "Call returns a scalar but caller expects aggregate!");
    }
    
    /// HandleAggregateResultAsScalar - This callback is invoked if the function
    /// returns an aggregate value by bit converting it to the specified scalar
    /// type and returning that.
    void HandleAggregateResultAsScalar(const Type *ScalarTy) {
      // There is nothing to do here.
    }
    
    /// HandleAggregateShadowArgument - This callback is invoked if the function
    /// returns an aggregate value by using a "shadow" first parameter.  If
    /// RetPtr is set to true, the pointer argument itself is returned from the
    /// function.
    void HandleAggregateShadowArgument(const PointerType *PtrArgTy,
                                       bool RetPtr) {
      // If the front-end has already made the argument explicit, don't do it
      // again.
      if (CALL_EXPR_HAS_RETURN_SLOT_ADDR(CallExpression))
        return;
      
      // Otherwise, we need to pass a buffer to return into.  If the caller uses
      // the result, DestLoc will be set.  If it ignores it, it could be unset,
      // in which case we need to create a dummy buffer.
      // FIXME: The alignment and volatility of the buffer are being ignored!
      Value *DestPtr;
      if (DestLoc == 0) {
        DestPtr = TheTreeToLLVM->CreateTemporary(PtrArgTy->getElementType());
      } else {
        DestPtr = DestLoc->Ptr;
        assert(PtrArgTy == DestPtr->getType());
      }
      CallOperands.push_back(DestPtr);
    }
    
    void HandleScalarArgument(const llvm::Type *LLVMTy, tree type) {
      assert(!LocStack.empty());
      Value *Loc = LocStack.back();
      if (cast<PointerType>(Loc->getType())->getElementType() != LLVMTy)
        // This always deals with pointer types so BitCast is appropriate
        Loc = Builder.CreateBitCast(Loc, PointerType::getUnqual(LLVMTy), "tmp");
      
      CallOperands.push_back(Builder.CreateLoad(Loc, "tmp"));
    }
    
    /// HandleByValArgument - This callback is invoked if the aggregate function
    /// argument is passed by value. It is lowered to a parameter passed by
    /// reference with an additional parameter attribute "ByVal".
    void HandleByValArgument(const llvm::Type *LLVMTy, tree type) {
      assert(!LocStack.empty());
      Value *Loc = LocStack.back();
      assert(PointerType::getUnqual(LLVMTy) == Loc->getType());
      CallOperands.push_back(Loc);
    }

    void EnterField(unsigned FieldNo, const llvm::Type *StructTy) {
      Constant *Zero = Constant::getNullValue(Type::Int32Ty);
      Constant *FIdx = ConstantInt::get(Type::Int32Ty, FieldNo);
      Value *Loc = LocStack.back();
      if (cast<PointerType>(Loc->getType())->getElementType() != StructTy)
        // This always deals with pointer types so BitCast is appropriate
        Loc = Builder.CreateBitCast(Loc, PointerType::getUnqual(StructTy), 
                                    "tmp");

      Value *Idxs[2] = { Zero, FIdx };
      LocStack.push_back(Builder.CreateGEP(Loc, Idxs, Idxs + 2, "tmp"));
    }
    void ExitField() {
      LocStack.pop_back();
    }
  };
}


/// EmitCallOf - Emit a call to the specified callee with the operands specified
/// in the CALL_EXP 'exp'.  If the result of the call is a scalar, return the
/// result, otherwise store it in DestLoc.
Value *TreeToLLVM::EmitCallOf(Value *Callee, tree exp, const MemRef *DestLoc,
                              const PAListPtr &InPAL) {
  PAListPtr PAL = InPAL;
  if (PAL.isEmpty() && isa<Function>(Callee))
    PAL = cast<Function>(Callee)->getParamAttrs();

  // Determine if we need to generate an invoke instruction (instead of a simple
  // call) and if so, what the exception destination will be.
  BasicBlock *UnwindBlock = 0;
  
  // Do not turn intrinsic calls or no-throw calls into invokes.
  if ((!isa<Function>(Callee) || !cast<Function>(Callee)->getIntrinsicID()) &&
      // Turn calls that throw that are inside of a cleanup scope into invokes.
      !CurrentEHScopes.empty() && tree_could_throw_p(exp) &&
      // Don't generate the unwind block for ObjC if it's using SJLJ exceptions.
      !(c_dialect_objc() && flag_objc_sjlj_exceptions)) {
    if (UnwindBB == 0)
      UnwindBB = new BasicBlock("Unwind");
    UnwindBlock = UnwindBB;
  }
  
  SmallVector<Value*, 16> CallOperands;
  CallingConv::ID CallingConvention;
  FunctionCallArgumentConversion Client(exp, CallOperands, CallingConvention,
                                        Builder, DestLoc);
  TheLLVMABI<FunctionCallArgumentConversion> ABIConverter(Client);

  // Handle the result, including struct returns.
  ABIConverter.HandleReturnType(TREE_TYPE(exp));

  // Pass the static chain, if any, as the first parameter.
  if (TREE_OPERAND(exp, 2))
    CallOperands.push_back(Emit(TREE_OPERAND(exp, 2), 0));

  // Loop over the arguments, expanding them and adding them to the op list.
  const PointerType *PFTy = cast<PointerType>(Callee->getType());
  const FunctionType *FTy = cast<FunctionType>(PFTy->getElementType());
  for (tree arg = TREE_OPERAND(exp, 1); arg; arg = TREE_CHAIN(arg)) {
    const Type *ActualArgTy = ConvertType(TREE_TYPE(TREE_VALUE(arg)));
    const Type *ArgTy = ActualArgTy;
    if (CallOperands.size() < FTy->getNumParams())
      ArgTy = FTy->getParamType(CallOperands.size());
    
    // If we are implicitly passing the address of this argument instead of 
    // passing it by value, handle this first.
    if (isPassedByInvisibleReference(TREE_TYPE(TREE_VALUE(arg)))) {
      // Get the address of the parameter passed in.
      LValue ArgVal = EmitLV(TREE_VALUE(arg));
      assert(!ArgVal.isBitfield() && "Bitfields shouldn't be invisible refs!");
      Value *Ptr = ArgVal.Ptr;
      
      if (CallOperands.size() >= FTy->getNumParams())
        ArgTy = PointerType::getUnqual(ArgTy);
      CallOperands.push_back(CastToType(Instruction::BitCast, Ptr, ArgTy));
    } else if (ActualArgTy->isFirstClassType()) {
      Value *V = Emit(TREE_VALUE(arg), 0);
      bool isSigned = !TYPE_UNSIGNED(TREE_TYPE(TREE_VALUE(arg)));
      CallOperands.push_back(CastToAnyType(V, isSigned, ArgTy, false));
    } else {
      // If this is an aggregate value passed by-value, use the current ABI to
      // determine how the parameters are passed.
      LValue LV = EmitLV(TREE_VALUE(arg));
      assert(!LV.isBitfield() && "Bitfields are first-class types!");
      Client.setLocation(LV.Ptr);
      ParameterAttributes Attributes = ParamAttr::None;
      ABIConverter.HandleArgument(TREE_TYPE(TREE_VALUE(arg)), &Attributes);
      if (Attributes != ParamAttr::None)
        PAL = PAL.addAttr(CallOperands.size(), Attributes);
    }
  }

  // Compile stuff like:
  //   %tmp = call float (...)* bitcast (float ()* @foo to float (...)*)( )
  // to:
  //   %tmp = call float @foo( )
  // This commonly occurs due to C "implicit ..." semantics.
  if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Callee)) {
    if (CallOperands.empty() && CE->getOpcode() == Instruction::BitCast) {
      Constant *RealCallee = CE->getOperand(0);
      assert(isa<PointerType>(RealCallee->getType()) &&
             "Bitcast to ptr not from ptr?");
      const PointerType *RealPT = cast<PointerType>(RealCallee->getType());
      if (const FunctionType *RealFT =
          dyn_cast<FunctionType>(RealPT->getElementType())) {
        const PointerType *ActualPT = cast<PointerType>(Callee->getType());
        const FunctionType *ActualFT =
          cast<FunctionType>(ActualPT->getElementType());
        if (RealFT->getReturnType() == ActualFT->getReturnType() &&
            ActualFT->getNumParams() == 0)
          Callee = RealCallee;
      }
    }
  }
  
  Value *Call;
  if (!UnwindBlock) {
    Call = Builder.CreateCall(Callee, CallOperands.begin(), CallOperands.end());
    cast<CallInst>(Call)->setCallingConv(CallingConvention);
    cast<CallInst>(Call)->setParamAttrs(PAL);
  } else {
    BasicBlock *NextBlock = new BasicBlock("invcont");
    Call = Builder.CreateInvoke(Callee, NextBlock, UnwindBlock,
                                CallOperands.begin(), CallOperands.end());
    cast<InvokeInst>(Call)->setCallingConv(CallingConvention);
    cast<InvokeInst>(Call)->setParamAttrs(PAL);

    // Lazily create an unwind block for this scope, which we can emit a fixup
    // branch in.
    if (CurrentEHScopes.back().UnwindBlock == 0) {
      EmitBlock(CurrentEHScopes.back().UnwindBlock = new BasicBlock("unwind"));
      
#ifdef ITANIUM_STYLE_EXCEPTIONS
      // Add landing pad entry code.
      AddLandingPad();
#endif
      // This branch to the unwind edge should have exception cleanups
      // inserted onto it.
      EmitBranchInternal(UnwindBlock, true);
    }

    cast<InvokeInst>(Call)->setUnwindDest(CurrentEHScopes.back().UnwindBlock);
    
    EmitBlock(NextBlock);
  }
  
  if (Call->getType() == Type::VoidTy)
    return 0;
  
  Call->setName("tmp");
    
  // If the caller expects an aggregate, we have a situation where the ABI for
  // the current target specifies that the aggregate be returned in scalar
  // registers even though it is an aggregate.  We must bitconvert the scalar
  // to the destination aggregate type.  We do this by casting the DestLoc
  // pointer and storing into it.
  if (!DestLoc)
    return Call;   // Normal scalar return.

  Value *Ptr = BitCastToType(DestLoc->Ptr,    
                             PointerType::getUnqual(Call->getType()));
  StoreInst *St = Builder.CreateStore(Call, Ptr, DestLoc->Volatile);
  St->setAlignment(DestLoc->Alignment);
  return 0;
}

/// HandleMultiplyDefinedGCCTemp - GCC temporaries are *mostly* single
/// definition, and always have all uses dominated by the definition.  In cases
/// where the temporary has multiple uses, we will first see the initial 
/// definition, some uses of that definition, then subsequently see another
/// definition with uses of this second definition.
///
/// Because LLVM temporaries *must* be single definition, when we see the second
/// definition, we actually change the temporary to mark it as not being a GCC
/// temporary anymore.  We then create an alloca for it, initialize it with the
/// first value seen, then treat it as a normal variable definition.
///
void TreeToLLVM::HandleMultiplyDefinedGCCTemp(tree Var) {
  Value *FirstVal = DECL_LLVM(Var);

  // Create a new temporary and set the VAR_DECL to use it as the llvm location.
  Value *NewTmp = CreateTemporary(FirstVal->getType());
  SET_DECL_LLVM(Var, NewTmp);

  // Store the already existing initial value into the alloca.  If the value
  // being stored is an instruction, emit the store right after the instruction,
  // otherwise, emit it into the entry block.
  StoreInst *SI = new StoreInst(FirstVal, NewTmp);
  
  BasicBlock::iterator InsertPt;
  if (Instruction *I = dyn_cast<Instruction>(FirstVal)) {
    InsertPt = I;                      // Insert after the init instruction.
    
    // If the instruction is an alloca in the entry block, the insert point
    // will be before the alloca.  Advance to the AllocaInsertionPoint if we are
    // before it.
    if (I->getParent() == &Fn->front()) {
      for (BasicBlock::iterator CI = InsertPt, E = Fn->begin()->end();
           CI != E; ++CI) {
        if (&*CI == AllocaInsertionPoint) {
          InsertPt = AllocaInsertionPoint;
          ++InsertPt;
          break;
        }
      }
    }
    
    // If the instruction is an invoke, the init is inserted on the normal edge.
    if (InvokeInst *II = dyn_cast<InvokeInst>(I)) {
      InsertPt = II->getNormalDest()->begin();
      while (isa<PHINode>(InsertPt))
        ++InsertPt;
    } else
      ++InsertPt; // Insert after the init instruction.
  } else {
    InsertPt = AllocaInsertionPoint;   // Insert after the allocas.
    ++InsertPt;
  }
  BasicBlock *BB = InsertPt->getParent();
  BB->getInstList().insert(InsertPt, SI);
  
  // Finally, This is no longer a GCC temporary.
  DECL_GIMPLE_FORMAL_TEMP_P(Var) = 0;
}

/// EmitMODIFY_EXPR - Note that MODIFY_EXPRs are rvalues only!
///
Value *TreeToLLVM::EmitMODIFY_EXPR(tree exp, const MemRef *DestLoc) {
  // If this is the definition of an SSA variable, set its DECL_LLVM to the
  // RHS.
  bool Op0Signed = !TYPE_UNSIGNED(TREE_TYPE(TREE_OPERAND(exp, 0)));
  bool Op1Signed = !TYPE_UNSIGNED(TREE_TYPE(TREE_OPERAND(exp, 1)));
  if (isGCC_SSA_Temporary(TREE_OPERAND(exp, 0))) {
    // If DECL_LLVM is already set, this is a multiply defined GCC temporary.
    if (DECL_LLVM_SET_P(TREE_OPERAND(exp, 0))) {
      HandleMultiplyDefinedGCCTemp(TREE_OPERAND(exp, 0));
      return EmitMODIFY_EXPR(exp, DestLoc);
    }
    
    Value *RHS = Emit(TREE_OPERAND(exp, 1), 0);
    RHS = CastToAnyType(RHS, Op1Signed, 
                        ConvertType(TREE_TYPE(TREE_OPERAND(exp, 0))), 
                        Op0Signed);
    SET_DECL_LLVM(TREE_OPERAND(exp, 0), RHS);
    return RHS;
  } else if (TREE_CODE(TREE_OPERAND(exp, 0)) == VAR_DECL &&
             DECL_REGISTER(TREE_OPERAND(exp, 0)) &&
             TREE_STATIC(TREE_OPERAND(exp, 0))) {
    // If this is a store to a register variable, EmitLV can't handle the dest
    // (there is no l-value of a register variable).  Emit an inline asm node
    // that copies the value into the specified register.
    Value *RHS = Emit(TREE_OPERAND(exp, 1), 0);
    RHS = CastToAnyType(RHS, Op1Signed,
                        ConvertType(TREE_TYPE(TREE_OPERAND(exp, 0))), 
                        Op0Signed);
    EmitModifyOfRegisterVariable(TREE_OPERAND(exp, 0), RHS);
    return RHS;
  }
  
  LValue LV = EmitLV(TREE_OPERAND(exp, 0));
  bool isVolatile = TREE_THIS_VOLATILE(TREE_OPERAND(exp, 0));
  unsigned Alignment = expr_align(TREE_OPERAND(exp, 0)) / 8;

  if (!LV.isBitfield()) {
    const Type *ValTy = ConvertType(TREE_TYPE(TREE_OPERAND(exp, 1)));
    if (ValTy->isFirstClassType()) {
      // Non-bitfield, scalar value.  Just emit a store.
      Value *RHS = Emit(TREE_OPERAND(exp, 1), 0);
      // Convert RHS to the right type if we can, otherwise convert the pointer.
      const PointerType *PT = cast<PointerType>(LV.Ptr->getType());
      if (PT->getElementType()->canLosslesslyBitCastTo(RHS->getType()))
        RHS = CastToAnyType(RHS, Op1Signed, PT->getElementType(), Op0Signed);
      else
        LV.Ptr = BitCastToType(LV.Ptr, PointerType::getUnqual(RHS->getType()));
      StoreInst *SI = Builder.CreateStore(RHS, LV.Ptr, isVolatile);
      SI->setAlignment(Alignment);
      return RHS;
    }

    // Non-bitfield aggregate value.
    MemRef NewLoc(LV.Ptr, Alignment, isVolatile);

    Emit(TREE_OPERAND(exp, 1), &NewLoc);
    if (DestLoc)
      EmitAggregateCopy(*DestLoc, NewLoc, TREE_TYPE(exp));
    return 0;
  }

  // Last case, this is a store to a bitfield, so we have to emit a 
  // read/modify/write sequence.

  Value *RHS = Emit(TREE_OPERAND(exp, 1), 0);

  if (!LV.BitSize)
    return RHS;

  const Type *ValTy = cast<PointerType>(LV.Ptr->getType())->getElementType();
  unsigned ValSizeInBits = ValTy->getPrimitiveSizeInBits();

  // The number of stores needed to write the entire bitfield.
  unsigned Strides = 1 + (LV.BitStart + LV.BitSize - 1) / ValSizeInBits;

  assert(ValTy->isInteger() && "Invalid bitfield lvalue!");
  assert(ValSizeInBits > LV.BitStart && "Bad bitfield lvalue!");
  assert(ValSizeInBits >= LV.BitSize && "Bad bitfield lvalue!");
  assert(2*ValSizeInBits > LV.BitSize+LV.BitStart && "Bad bitfield lvalue!");

  Value *BitSource = CastToAnyType(RHS, Op1Signed, ValTy, Op0Signed);

  for (unsigned I = 0; I < Strides; I++) {
    unsigned Index = BYTES_BIG_ENDIAN ? Strides - I - 1 : I; // LSB first
    unsigned ThisFirstBit = Index * ValSizeInBits;
    unsigned ThisLastBitPlusOne = ThisFirstBit + ValSizeInBits;
    if (ThisFirstBit < LV.BitStart)
      ThisFirstBit = LV.BitStart;
    if (ThisLastBitPlusOne > LV.BitStart+LV.BitSize)
      ThisLastBitPlusOne = LV.BitStart+LV.BitSize;

    Value *Ptr = Index ?
      Builder.CreateGEP(LV.Ptr, ConstantInt::get(Type::Int32Ty, Index),
                        "tmp") : LV.Ptr;
    LoadInst *LI = Builder.CreateLoad(Ptr, isVolatile, "tmp");
    LI->setAlignment(Alignment);
    Value *OldVal = LI;
    Value *NewVal = BitSource;

    unsigned BitsInVal = ThisLastBitPlusOne - ThisFirstBit;
    unsigned FirstBitInVal = ThisFirstBit % ValSizeInBits;

    // If this target has bitfields laid out in big-endian order, invert the bit
    // in the word if needed.
    if (BITS_BIG_ENDIAN)
      FirstBitInVal = ValSizeInBits-FirstBitInVal-BitsInVal;

    // If not storing into the zero'th bit, shift the Src value to the left.
    if (FirstBitInVal) {
      Value *ShAmt = ConstantInt::get(ValTy, FirstBitInVal);
      NewVal = Builder.CreateShl(NewVal, ShAmt, "tmp");
    }

    // Next, if this doesn't touch the top bit, mask out any bits that shouldn't
    // be set in the result.
    uint64_t MaskVal = ((1ULL << BitsInVal)-1) << FirstBitInVal;
    Constant *Mask = ConstantInt::get(Type::Int64Ty, MaskVal);
    Mask = ConstantExpr::getTruncOrBitCast(Mask, ValTy);

    if (FirstBitInVal+BitsInVal != ValSizeInBits)
      NewVal = Builder.CreateAnd(NewVal, Mask, "tmp");

    // Next, mask out the bits this bit-field should include from the old value.
    Mask = ConstantExpr::getNot(Mask);
    OldVal = Builder.CreateAnd(OldVal, Mask, "tmp");

    // Finally, merge the two together and store it.
    NewVal = Builder.CreateOr(OldVal, NewVal, "tmp");

    StoreInst *SI = Builder.CreateStore(NewVal, Ptr, isVolatile);
    SI->setAlignment(Alignment);

    if (I + 1 < Strides) {
      Value *ShAmt = ConstantInt::get(ValTy, BitsInVal);
      BitSource = Builder.CreateLShr(BitSource, ShAmt, "tmp");
    }
  }

  return RHS;
}

Value *TreeToLLVM::EmitNOP_EXPR(tree exp, const MemRef *DestLoc) {
  if (TREE_CODE(TREE_TYPE(exp)) == VOID_TYPE &&    // deleted statement.
      TREE_CODE(TREE_OPERAND(exp, 0)) == INTEGER_CST)
    return 0;
  tree Op = TREE_OPERAND(exp, 0);
  const Type *Ty = ConvertType(TREE_TYPE(exp));
  bool OpIsSigned = !TYPE_UNSIGNED(TREE_TYPE(Op));
  bool ExpIsSigned = !TYPE_UNSIGNED(TREE_TYPE(exp));
  if (DestLoc == 0) {
    // Scalar to scalar copy.
    assert(!isAggregateTreeType(TREE_TYPE(Op))
	   && "Aggregate to scalar nop_expr!");
    Value *OpVal = Emit(Op, DestLoc);
    if (Ty == Type::VoidTy) return 0;
    return CastToAnyType(OpVal, OpIsSigned, Ty, ExpIsSigned);
  } else if (isAggregateTreeType(TREE_TYPE(Op))) {
    // Aggregate to aggregate copy.
    MemRef NewLoc = *DestLoc;
    NewLoc.Ptr =
      CastToType(Instruction::BitCast, DestLoc->Ptr, 
                 PointerType::getUnqual(Ty));
    Value *OpVal = Emit(Op, &NewLoc);
    assert(OpVal == 0 && "Shouldn't cast scalar to aggregate!");
    return 0;
  } 

  // Scalar to aggregate copy.
  Value *OpVal = Emit(Op, 0);
  Value *Ptr = CastToType(Instruction::BitCast, DestLoc->Ptr,
                          PointerType::getUnqual(OpVal->getType()));
  StoreInst *St = Builder.CreateStore(OpVal, Ptr, DestLoc->Volatile);
  St->setAlignment(DestLoc->Alignment);
  return 0;
}

Value *TreeToLLVM::EmitCONVERT_EXPR(tree exp, const MemRef *DestLoc) {
  assert(!DestLoc && "Cannot handle aggregate casts!");
  Value *Op = Emit(TREE_OPERAND(exp, 0), 0);
  bool OpIsSigned = !TYPE_UNSIGNED(TREE_TYPE(TREE_OPERAND(exp, 0)));
  bool ExpIsSigned = !TYPE_UNSIGNED(TREE_TYPE(exp));
  return CastToAnyType(Op, OpIsSigned, ConvertType(TREE_TYPE(exp)),ExpIsSigned);
}

Value *TreeToLLVM::EmitVIEW_CONVERT_EXPR(tree exp, const MemRef *DestLoc) {
  tree Op = TREE_OPERAND(exp, 0);

  if (isAggregateTreeType(TREE_TYPE(Op))) {
    const Type *OpTy = ConvertType(TREE_TYPE(Op));
    MemRef Target;
    if (DestLoc) {
      // This is an aggregate-to-agg VIEW_CONVERT_EXPR, just evaluate in place.
      Target = *DestLoc;
      Target.Ptr =
        CastToType(Instruction::BitCast, DestLoc->Ptr, 
                   PointerType::getUnqual(OpTy));
    } else {
      // This is an aggregate-to-scalar VIEW_CONVERT_EXPR, evaluate, then load.
      Target = CreateTempLoc(OpTy);
    }

    switch (TREE_CODE(Op)) {
    default: {
      Value *OpVal = Emit(Op, &Target);
      assert(OpVal == 0 && "Expected an aggregate operand!");
      break;
    }

    // Lvalues
    case VAR_DECL:
    case PARM_DECL:
    case RESULT_DECL:
    case INDIRECT_REF:
    case ARRAY_REF:
    case ARRAY_RANGE_REF:
    case COMPONENT_REF:
    case BIT_FIELD_REF:
    case STRING_CST:
    case REALPART_EXPR:
    case IMAGPART_EXPR:
      // Same as EmitLoadOfLValue but taking the size from TREE_TYPE(exp), since
      // the size of TREE_TYPE(Op) may not be available.
      LValue LV = EmitLV(Op);
      assert(!LV.isBitfield() && "Expected an aggregate operand!");
      bool isVolatile = TREE_THIS_VOLATILE(Op);
      unsigned Alignment = expr_align(Op) / 8;

      EmitAggregateCopy(Target, MemRef(LV.Ptr, Alignment, isVolatile),
                        TREE_TYPE(exp));
      break;
    }

    if (DestLoc)
      return 0;

    // Target holds the temporary created above.
    const Type *ExpTy = ConvertType(TREE_TYPE(exp));
    return Builder.CreateLoad(CastToType(Instruction::BitCast, Target.Ptr,
                                         PointerType::getUnqual(ExpTy)), "tmp");
  }
  
  if (DestLoc) {
    // The input is a scalar the output is an aggregate, just eval the input,
    // then store into DestLoc.
    Value *OpVal = Emit(Op, 0);
    assert(OpVal && "Expected a scalar result!");
    Value *Ptr = CastToType(Instruction::BitCast, DestLoc->Ptr,
                            PointerType::getUnqual(OpVal->getType()));
    StoreInst *St = Builder.CreateStore(OpVal, Ptr, DestLoc->Volatile);
    St->setAlignment(DestLoc->Alignment);
    return 0;
  }

  // Otherwise, this is a scalar to scalar conversion.
  Value *OpVal = Emit(Op, 0);
  assert(OpVal && "Expected a scalar result!");
  const Type *DestTy = ConvertType(TREE_TYPE(exp));
  
  // If the source is a pointer, use ptrtoint to get it to something
  // bitcast'able.  This supports things like v_c_e(foo*, float).
  if (isa<PointerType>(OpVal->getType())) {
    if (isa<PointerType>(DestTy))   // ptr->ptr is a simple bitcast.
      return Builder.CreateBitCast(OpVal, DestTy, "tmp");
    // Otherwise, ptrtoint to intptr_t first.
    OpVal = Builder.CreatePtrToInt(OpVal, TD.getIntPtrType(), "tmp");
  }
  
  // If the destination type is a pointer, use inttoptr.
  if (isa<PointerType>(DestTy))
    return Builder.CreateIntToPtr(OpVal, DestTy, "tmp");

  // Otherwise, use a bitcast.
  return Builder.CreateBitCast(OpVal, DestTy, "tmp");
}

Value *TreeToLLVM::EmitNEGATE_EXPR(tree exp, const MemRef *DestLoc) {
  if (!DestLoc) {
    Value *V = Emit(TREE_OPERAND(exp, 0), 0);
    if (!isa<PointerType>(V->getType()))
      return Builder.CreateNeg(V, "tmp");
    
    // GCC allows NEGATE_EXPR on pointers as well.  Cast to int, negate, cast
    // back.
    V = CastToAnyType(V, false, TD.getIntPtrType(), false);
    V = Builder.CreateNeg(V, "tmp");
    return CastToType(Instruction::IntToPtr, V, ConvertType(TREE_TYPE(exp)));
  }
  
  // Emit the operand to a temporary.
  const Type *ComplexTy =
    cast<PointerType>(DestLoc->Ptr->getType())->getElementType();
  MemRef Tmp = CreateTempLoc(ComplexTy);
  Emit(TREE_OPERAND(exp, 0), &Tmp);

  // Handle complex numbers: -(a+ib) = -a + i*-b
  Value *R, *I;
  EmitLoadFromComplex(R, I, Tmp);
  R = Builder.CreateNeg(R, "tmp");
  I = Builder.CreateNeg(I, "tmp");
  EmitStoreToComplex(*DestLoc, R, I);
  return 0;
}

Value *TreeToLLVM::EmitCONJ_EXPR(tree exp, const MemRef *DestLoc) {
  assert(DestLoc && "CONJ_EXPR only applies to complex numbers.");
  // Emit the operand to a temporary.
  const Type *ComplexTy =
    cast<PointerType>(DestLoc->Ptr->getType())->getElementType();
  MemRef Tmp = CreateTempLoc(ComplexTy);
  Emit(TREE_OPERAND(exp, 0), &Tmp);
  
  // Handle complex numbers: ~(a+ib) = a + i*-b
  Value *R, *I;
  EmitLoadFromComplex(R, I, Tmp);
  I = Builder.CreateNeg(I, "tmp");
  EmitStoreToComplex(*DestLoc, R, I);
  return 0;
}

Value *TreeToLLVM::EmitABS_EXPR(tree exp) {
  Value *Op = Emit(TREE_OPERAND(exp, 0), 0);
  if (!Op->getType()->isFloatingPoint()) {
    Instruction *OpN = Builder.CreateNeg(Op, (Op->getName()+"neg").c_str());
    ICmpInst::Predicate pred = TYPE_UNSIGNED(TREE_TYPE(TREE_OPERAND(exp, 0))) ?
      ICmpInst::ICMP_UGE : ICmpInst::ICMP_SGE;
    Value *Cmp = Builder.CreateICmp(pred, Op, OpN->getOperand(0), "abscond");
    return Builder.CreateSelect(Cmp, Op, OpN, "abs");
  } else {
    // Turn FP abs into fabs/fabsf.
    return EmitBuiltinUnaryFPOp(Op, "fabsf", "fabs", "fabsl");
  }
}

Value *TreeToLLVM::EmitBIT_NOT_EXPR(tree exp) {
  Value *Op = Emit(TREE_OPERAND(exp, 0), 0);
  if (isa<PointerType>(Op->getType())) {
    assert (TREE_CODE(TREE_TYPE(exp)) == INTEGER_TYPE &&
            "Expected integer type here");
    Op = CastToType(Instruction::PtrToInt, Op, TREE_TYPE(exp));
  }
  return Builder.CreateNot(Op, (Op->getName()+"not").c_str());
}

Value *TreeToLLVM::EmitTRUTH_NOT_EXPR(tree exp) {
  Value *V = Emit(TREE_OPERAND(exp, 0), 0);
  if (V->getType() != Type::Int1Ty) 
    V = Builder.CreateICmpNE(V, Constant::getNullValue(V->getType()), "toBool");
  V = Builder.CreateNot(V, (V->getName()+"not").c_str());
  return CastToUIntType(V, ConvertType(TREE_TYPE(exp)));
}

/// EmitCompare - 'exp' is a comparison of two values.  Opc is the base LLVM
/// comparison to use.  isUnord is true if this is a floating point comparison
/// that should also be true if either operand is a NaN.  Note that Opc can be
/// set to zero for special cases.
Value *TreeToLLVM::EmitCompare(tree exp, unsigned UIOpc, unsigned SIOpc, 
                               unsigned FPPred) {
  // Get the type of the operands
  tree Op0Ty = TREE_TYPE(TREE_OPERAND(exp,0));

  // Deal with complex types
  if (TREE_CODE(Op0Ty) == COMPLEX_TYPE)
    return EmitComplexBinOp(exp, 0);  // Complex ==/!=

  // Get the compare operands, in the right type. Comparison of struct is not
  // allowed, so this is safe as we already handled complex (struct) type.
  Value *LHS = Emit(TREE_OPERAND(exp, 0), 0);
  Value *RHS = Emit(TREE_OPERAND(exp, 1), 0);
  bool LHSIsSigned = !TYPE_UNSIGNED(TREE_TYPE(TREE_OPERAND(exp, 0)));
  bool RHSIsSigned = !TYPE_UNSIGNED(TREE_TYPE(TREE_OPERAND(exp, 1)));
  RHS = CastToAnyType(RHS, RHSIsSigned, LHS->getType(), LHSIsSigned);
  assert(LHS->getType() == RHS->getType() && "Binop type equality failure!");

  // Handle the integer/pointer cases
  if (!FLOAT_TYPE_P(Op0Ty)) {
    // Determine which predicate to use based on signedness
    ICmpInst::Predicate pred = 
      ICmpInst::Predicate(TYPE_UNSIGNED(Op0Ty) ? UIOpc : SIOpc);

    // Get the compare instructions
    Value *Result = Builder.CreateICmp(pred, LHS, RHS, "tmp");
    
    // The GCC type is probably an int, not a bool.
    return CastToUIntType(Result, ConvertType(TREE_TYPE(exp)));
  }

  // Handle floating point comparisons, if we get here.
  Value *Result = Builder.CreateFCmp(FCmpInst::Predicate(FPPred),
                                     LHS, RHS, "tmp");
  
  // The GCC type is probably an int, not a bool.
  return CastToUIntType(Result, ConvertType(TREE_TYPE(exp)));
}

/// EmitBinOp - 'exp' is a binary operator.
///
Value *TreeToLLVM::EmitBinOp(tree exp, const MemRef *DestLoc, unsigned Opc) {
  const Type *Ty = ConvertType(TREE_TYPE(exp));
  if (isa<PointerType>(Ty))
    return EmitPtrBinOp(exp, Opc);   // Pointer arithmetic!
  if (isa<StructType>(Ty))
    return EmitComplexBinOp(exp, DestLoc);
  assert(Ty->isFirstClassType() && DestLoc == 0 &&
         "Bad binary operation!");
  
  Value *LHS = Emit(TREE_OPERAND(exp, 0), 0);
  Value *RHS = Emit(TREE_OPERAND(exp, 1), 0);
  
  // GCC has no problem with things like "xor uint X, int 17", and X-Y, where
  // X and Y are pointer types, but the result is an integer.  As such, convert
  // everything to the result type.
  bool LHSIsSigned = !TYPE_UNSIGNED(TREE_TYPE(TREE_OPERAND(exp, 0)));
  bool RHSIsSigned = !TYPE_UNSIGNED(TREE_TYPE(TREE_OPERAND(exp, 1)));
  bool TyIsSigned  = !TYPE_UNSIGNED(TREE_TYPE(exp));
  LHS = CastToAnyType(LHS, LHSIsSigned, Ty, TyIsSigned);
  RHS = CastToAnyType(RHS, RHSIsSigned, Ty, TyIsSigned);

  return Builder.CreateBinOp((Instruction::BinaryOps)Opc, LHS, RHS, "tmp");
}

/// EmitPtrBinOp - Handle binary expressions involving pointers, e.g. "P+4".
///
Value *TreeToLLVM::EmitPtrBinOp(tree exp, unsigned Opc) {
  Value *LHS = Emit(TREE_OPERAND(exp, 0), 0);
  
  // If this is an expression like (P+4), try to turn this into
  // "getelementptr P, 1".
  if ((Opc == Instruction::Add || Opc == Instruction::Sub) &&
      TREE_CODE(TREE_OPERAND(exp, 1)) == INTEGER_CST) {
    int64_t Offset = getINTEGER_CSTVal(TREE_OPERAND(exp, 1));
    
    // If POINTER_SIZE is 32-bits and the offset is signed, sign extend it.
    if (POINTER_SIZE == 32 && !TYPE_UNSIGNED(TREE_TYPE(TREE_OPERAND(exp, 1))))
      Offset = (Offset << 32) >> 32;
    
    // Figure out how large the element pointed to is.
    const Type *ElTy = cast<PointerType>(LHS->getType())->getElementType();
    // We can't get the type size (and thus convert to using a GEP instr) from
    // pointers to opaque structs if the type isn't abstract.
    if (ElTy->isSized()) {
      int64_t EltSize = TD.getABITypeSize(ElTy);
      
      // If EltSize exactly divides Offset, then we know that we can turn this
      // into a getelementptr instruction.
      int64_t EltOffset = EltSize ? Offset/EltSize : 0;
      if (EltOffset*EltSize == Offset) {
        // If this is a subtract, we want to step backwards.
        if (Opc == Instruction::Sub)
          EltOffset = -EltOffset;
        Constant *C = ConstantInt::get(Type::Int64Ty, EltOffset);
        Value *V = Builder.CreateGEP(LHS, C, "tmp");
        return CastToType(Instruction::BitCast, V, TREE_TYPE(exp));
      }
    }
  }
  
  
  Value *RHS = Emit(TREE_OPERAND(exp, 1), 0);

  const Type *IntPtrTy = TD.getIntPtrType();
  bool LHSIsSigned = !TYPE_UNSIGNED(TREE_TYPE(TREE_OPERAND(exp, 0)));
  bool RHSIsSigned = !TYPE_UNSIGNED(TREE_TYPE(TREE_OPERAND(exp, 1)));
  LHS = CastToAnyType(LHS, LHSIsSigned, IntPtrTy, false);
  RHS = CastToAnyType(RHS, RHSIsSigned, IntPtrTy, false);
  Value *V = Builder.CreateBinOp((Instruction::BinaryOps)Opc, LHS, RHS, "tmp");
  return CastToType(Instruction::IntToPtr, V, ConvertType(TREE_TYPE(exp)));
}


Value *TreeToLLVM::EmitTruthOp(tree exp, unsigned Opc) {
  Value *LHS = Emit(TREE_OPERAND(exp, 0), 0);
  Value *RHS = Emit(TREE_OPERAND(exp, 1), 0);
  bool LHSIsSigned = !TYPE_UNSIGNED(TREE_TYPE(TREE_OPERAND(exp, 0)));
  bool RHSIsSigned = !TYPE_UNSIGNED(TREE_TYPE(TREE_OPERAND(exp, 1)));
  
  // This is a truth operation like the strict &&,||,^^.  Convert to bool as
  // a test against zero
  LHS = Builder.CreateICmpNE(LHS, Constant::getNullValue(LHS->getType()),
                             "toBool");
  RHS = Builder.CreateICmpNE(RHS, Constant::getNullValue(RHS->getType()),
                             "toBool");
  
  Value *Res = Builder.CreateBinOp((Instruction::BinaryOps)Opc, LHS, RHS,"tmp");
  return CastToType(Instruction::ZExt, Res, ConvertType(TREE_TYPE(exp)));
}


Value *TreeToLLVM::EmitShiftOp(tree exp, const MemRef *DestLoc, unsigned Opc) {
  assert(DestLoc == 0 && "aggregate shift?");
  const Type *Ty = ConvertType(TREE_TYPE(exp));
  assert(!isa<PointerType>(Ty) && "Pointer arithmetic!?");
  
  Value *LHS = Emit(TREE_OPERAND(exp, 0), 0);
  Value *RHS = Emit(TREE_OPERAND(exp, 1), 0);
  if (RHS->getType() != LHS->getType())
    RHS = Builder.CreateIntCast(RHS, LHS->getType(), false,
                                (RHS->getName()+".cast").c_str());
  
  return Builder.CreateBinOp((Instruction::BinaryOps)Opc, LHS, RHS, "tmp");
}

Value *TreeToLLVM::EmitRotateOp(tree exp, unsigned Opc1, unsigned Opc2) {
  Value *In  = Emit(TREE_OPERAND(exp, 0), 0);
  Value *Amt = Emit(TREE_OPERAND(exp, 1), 0);
  if (Amt->getType() != In->getType())
    Amt = Builder.CreateIntCast(Amt, In->getType(), false,
                                (Amt->getName()+".cast").c_str());

  Value *TypeSize =
    ConstantInt::get(In->getType(), In->getType()->getPrimitiveSizeInBits());
  
  // Do the two shifts.
  Value *V1 = Builder.CreateBinOp((Instruction::BinaryOps)Opc1, In, Amt, "tmp");
  Value *OtherShift = Builder.CreateSub(TypeSize, Amt, "tmp");
  Value *V2 = Builder.CreateBinOp((Instruction::BinaryOps)Opc2, In, 
                                  OtherShift, "tmp");
  
  // Or the two together to return them.
  Value *Merge = Builder.CreateOr(V1, V2, "tmp");
  return CastToUIntType(Merge, ConvertType(TREE_TYPE(exp)));
}

Value *TreeToLLVM::EmitMinMaxExpr(tree exp, unsigned UIPred, unsigned SIPred, 
                                  unsigned FPPred) {
  Value *LHS = Emit(TREE_OPERAND(exp, 0), 0);
  Value *RHS = Emit(TREE_OPERAND(exp, 1), 0);

  const Type *Ty = ConvertType(TREE_TYPE(exp));

  // The LHS, RHS and Ty could be integer, floating or pointer typed. We need
  // to convert the LHS and RHS into the destination type before doing the 
  // comparison. Use CastInst::getCastOpcode to get this right.
  bool TyIsSigned  = !TYPE_UNSIGNED(TREE_TYPE(exp));
  bool LHSIsSigned = !TYPE_UNSIGNED(TREE_TYPE(TREE_OPERAND(exp, 0)));
  bool RHSIsSigned = !TYPE_UNSIGNED(TREE_TYPE(TREE_OPERAND(exp, 1)));
  Instruction::CastOps opcode = 
    CastInst::getCastOpcode(LHS, LHSIsSigned, Ty, TyIsSigned);
  LHS = CastToType(opcode, LHS, Ty);
  opcode = CastInst::getCastOpcode(RHS, RHSIsSigned, Ty, TyIsSigned);
  RHS = CastToType(opcode, RHS, Ty);
  
  Value *Compare;
  if (LHS->getType()->isFloatingPoint())
    Compare = Builder.CreateFCmp(FCmpInst::Predicate(FPPred), LHS, RHS, "tmp");
  else if TYPE_UNSIGNED(TREE_TYPE(TREE_OPERAND(exp, 0)))
    Compare = Builder.CreateICmp(ICmpInst::Predicate(UIPred), LHS, RHS, "tmp");
  else
    Compare = Builder.CreateICmp(ICmpInst::Predicate(SIPred), LHS, RHS, "tmp");

  return Builder.CreateSelect(Compare, LHS, RHS,
                              TREE_CODE(exp) == MAX_EXPR ? "max" : "min");
}

Value *TreeToLLVM::EmitEXACT_DIV_EXPR(tree exp, const MemRef *DestLoc) {
  // Unsigned EXACT_DIV_EXPR -> normal udiv.
  if (TYPE_UNSIGNED(TREE_TYPE(exp)))
    return EmitBinOp(exp, DestLoc, Instruction::UDiv);
  
  // If this is a signed EXACT_DIV_EXPR by a constant, and we know that
  // the RHS is a multiple of two, we strength reduce the result to use
  // a signed SHR here.  We have no way in LLVM to represent EXACT_DIV_EXPR
  // precisely, so this transform can't currently be performed at the LLVM
  // level.  This is commonly used for pointer subtraction. 
  if (TREE_CODE(TREE_OPERAND(exp, 1)) == INTEGER_CST) {
    uint64_t IntValue = getINTEGER_CSTVal(TREE_OPERAND(exp, 1));
    if (isPowerOf2_64(IntValue)) {
      // Create an ashr instruction, by the log of the division amount.
      Value *LHS = Emit(TREE_OPERAND(exp, 0), 0);
      return Builder.CreateAShr(LHS, ConstantInt::get(LHS->getType(),
                                                      Log2_64(IntValue)),"tmp");
    }
  }
  
  // Otherwise, emit this as a normal signed divide.
  return EmitBinOp(exp, DestLoc, Instruction::SDiv);
}

Value *TreeToLLVM::EmitFLOOR_MOD_EXPR(tree exp, const MemRef *DestLoc) {
  // Notation: FLOOR_MOD_EXPR <-> Mod, TRUNC_MOD_EXPR <-> Rem.
  
  // We express Mod in terms of Rem as follows: if RHS exactly divides LHS,
  // or the values of LHS and RHS have the same sign, then Mod equals Rem.
  // Otherwise Mod equals Rem + RHS.  This means that LHS Mod RHS traps iff
  // LHS Rem RHS traps.
  if (TYPE_UNSIGNED(TREE_TYPE(exp)))
    // LHS and RHS values must have the same sign if their type is unsigned.
    return EmitBinOp(exp, DestLoc, Instruction::URem);
  
  const Type *Ty = ConvertType(TREE_TYPE(exp));
  Constant *Zero = ConstantInt::get(Ty, 0);
  
  Value *LHS = Emit(TREE_OPERAND(exp, 0), 0);
  Value *RHS = Emit(TREE_OPERAND(exp, 1), 0);
  
  // The two possible values for Mod.
  Value *Rem = Builder.CreateSRem(LHS, RHS, "rem");
  Value *RemPlusRHS = Builder.CreateAdd(Rem, RHS, "tmp");
  
  // HaveSameSign: (LHS >= 0) == (RHS >= 0).
  Value *LHSIsPositive = Builder.CreateICmpSGE(LHS, Zero, "tmp");
  Value *RHSIsPositive = Builder.CreateICmpSGE(RHS, Zero, "tmp");
  Value *HaveSameSign = Builder.CreateICmpEQ(LHSIsPositive,RHSIsPositive,"tmp");
  
  // RHS exactly divides LHS iff Rem is zero.
  Value *RemIsZero = Builder.CreateICmpEQ(Rem, Zero, "tmp");
  
  Value *SameAsRem = Builder.CreateOr(HaveSameSign, RemIsZero, "tmp");
  return Builder.CreateSelect(SameAsRem, Rem, RemPlusRHS, "mod");
}

Value *TreeToLLVM::EmitCEIL_DIV_EXPR(tree exp) {
  // Notation: CEIL_DIV_EXPR <-> CDiv, TRUNC_DIV_EXPR <-> Div.

  // CDiv calculates LHS/RHS by rounding up to the nearest integer.  In terms
  // of Div this means if the values of LHS and RHS have opposite signs or if
  // LHS is zero, then CDiv necessarily equals Div; and
  //   LHS CDiv RHS = (LHS - Sign(RHS)) Div RHS + 1
  // otherwise.

  const Type *Ty = ConvertType(TREE_TYPE(exp));
  Constant *Zero = ConstantInt::get(Ty, 0);
  Constant *One = ConstantInt::get(Ty, 1);
  Constant *MinusOne = ConstantInt::getAllOnesValue(Ty);

  Value *LHS = Emit(TREE_OPERAND(exp, 0), 0);
  Value *RHS = Emit(TREE_OPERAND(exp, 1), 0);

  if (!TYPE_UNSIGNED(TREE_TYPE(exp))) {
    // In the case of signed arithmetic, we calculate CDiv as follows:
    //   LHS CDiv RHS = (LHS - Sign(RHS) * Offset) Div RHS + Offset,
    // where Offset is 1 if LHS and RHS have the same sign and LHS is
    // not zero, and 0 otherwise.

    // On some machines INT_MIN Div -1 traps.  You might expect a trap for
    // INT_MIN CDiv -1 too, but this implementation will not generate one.
    // Quick quiz question: what value is returned for INT_MIN CDiv -1?

    // Determine the signs of LHS and RHS, and whether they have the same sign.
    Value *LHSIsPositive = Builder.CreateICmpSGE(LHS, Zero, "tmp");
    Value *RHSIsPositive = Builder.CreateICmpSGE(RHS, Zero, "tmp");
    Value *HaveSameSign = Builder.CreateICmpEQ(LHSIsPositive, RHSIsPositive,
                                             "tmp");

    // Offset equals 1 if LHS and RHS have the same sign and LHS is not zero.
    Value *LHSNotZero = Builder.CreateICmpNE(LHS, Zero, "tmp");
    Value *OffsetOne = Builder.CreateAnd(HaveSameSign, LHSNotZero, "tmp");
    // ... otherwise it is 0.
    Value *Offset = Builder.CreateSelect(OffsetOne, One, Zero, "tmp");

    // Calculate Sign(RHS) ...
    Value *SignRHS = Builder.CreateSelect(RHSIsPositive, One, MinusOne, "tmp");
    // ... and Sign(RHS) * Offset
    Value *SignedOffset = CastToType(Instruction::SExt, OffsetOne, Ty);
    SignedOffset = Builder.CreateAnd(SignRHS, SignedOffset, "tmp");

    // Return CDiv = (LHS - Sign(RHS) * Offset) Div RHS + Offset.
    Value *CDiv = Builder.CreateSub(LHS, SignedOffset, "tmp");
    CDiv = Builder.CreateSDiv(CDiv, RHS, "tmp");
    return Builder.CreateAdd(CDiv, Offset, "cdiv");
  }

  // In the case of unsigned arithmetic, LHS and RHS necessarily have the
  // same sign, so we can use
  //   LHS CDiv RHS = (LHS - 1) Div RHS + 1
  // as long as LHS is non-zero.

  // Offset is 1 if LHS is non-zero, 0 otherwise.
  Value *LHSNotZero = Builder.CreateICmpNE(LHS, Zero, "tmp");
  Value *Offset = Builder.CreateSelect(LHSNotZero, One, Zero, "tmp");

  // Return CDiv = (LHS - Offset) Div RHS + Offset.
  Value *CDiv = Builder.CreateSub(LHS, Offset, "tmp");
  CDiv = Builder.CreateUDiv(CDiv, RHS, "tmp");
  return Builder.CreateAdd(CDiv, Offset, "cdiv");
}

Value *TreeToLLVM::EmitROUND_DIV_EXPR(tree exp) {
  // Notation: ROUND_DIV_EXPR <-> RDiv, TRUNC_DIV_EXPR <-> Div.
  
  // RDiv calculates LHS/RHS by rounding to the nearest integer.  Ties
  // are broken by rounding away from zero.  In terms of Div this means:
  //   LHS RDiv RHS = (LHS + (RHS Div 2)) Div RHS
  // if the values of LHS and RHS have the same sign; and
  //   LHS RDiv RHS = (LHS - (RHS Div 2)) Div RHS
  // if the values of LHS and RHS differ in sign.  The intermediate
  // expressions in these formulae can overflow, so some tweaking is
  // required to ensure correct results.  The details depend on whether
  // we are doing signed or unsigned arithmetic.
  
  const Type *Ty = ConvertType(TREE_TYPE(exp));
  Constant *Zero = ConstantInt::get(Ty, 0);
  Constant *Two = ConstantInt::get(Ty, 2);
  
  Value *LHS = Emit(TREE_OPERAND(exp, 0), 0);
  Value *RHS = Emit(TREE_OPERAND(exp, 1), 0);
  
  if (!TYPE_UNSIGNED(TREE_TYPE(exp))) {
    // In the case of signed arithmetic, we calculate RDiv as follows:
    //   LHS RDiv RHS = (sign) ( (|LHS| + (|RHS| UDiv 2)) UDiv |RHS| ),
    // where sign is +1 if LHS and RHS have the same sign, -1 if their
    // signs differ.  Doing the computation unsigned ensures that there
    // is no overflow.
    
    // On some machines INT_MIN Div -1 traps.  You might expect a trap for
    // INT_MIN RDiv -1 too, but this implementation will not generate one.
    // Quick quiz question: what value is returned for INT_MIN RDiv -1?
    
    // Determine the signs of LHS and RHS, and whether they have the same sign.
    Value *LHSIsPositive = Builder.CreateICmpSGE(LHS, Zero, "tmp");
    Value *RHSIsPositive = Builder.CreateICmpSGE(RHS, Zero, "tmp");
    Value *HaveSameSign = Builder.CreateICmpEQ(LHSIsPositive, RHSIsPositive,
                                               "tmp");
    
    // Calculate |LHS| ...
    Value *MinusLHS = Builder.CreateNeg(LHS, "tmp");
    Value *AbsLHS = Builder.CreateSelect(LHSIsPositive, LHS, MinusLHS,
                                         (LHS->getNameStr()+".abs").c_str());
    // ... and |RHS|
    Value *MinusRHS = Builder.CreateNeg(RHS, "tmp");
    Value *AbsRHS = Builder.CreateSelect(RHSIsPositive, RHS, MinusRHS,
                                         (RHS->getNameStr()+".abs").c_str());
    
    // Calculate AbsRDiv = (|LHS| + (|RHS| UDiv 2)) UDiv |RHS|.
    Value *HalfAbsRHS = Builder.CreateUDiv(AbsRHS, Two, "tmp");
    Value *Numerator = Builder.CreateAdd(AbsLHS, HalfAbsRHS, "tmp");
    Value *AbsRDiv = Builder.CreateUDiv(Numerator, AbsRHS, "tmp");
    
    // Return AbsRDiv or -AbsRDiv according to whether LHS and RHS have the
    // same sign or not.
    Value *MinusAbsRDiv = Builder.CreateNeg(AbsRDiv, "tmp");
    return Builder.CreateSelect(HaveSameSign, AbsRDiv, MinusAbsRDiv, "rdiv");
  }
  
  // In the case of unsigned arithmetic, LHS and RHS necessarily have the
  // same sign, however overflow is a problem.  We want to use the formula
  //   LHS RDiv RHS = (LHS + (RHS Div 2)) Div RHS,
  // but if LHS + (RHS Div 2) overflows then we get the wrong result.  Since
  // the use of a conditional branch seems to be unavoidable, we choose the
  // simple solution of explicitly checking for overflow, and using
  //   LHS RDiv RHS = ((LHS + (RHS Div 2)) - RHS) Div RHS + 1
  // if it occurred.
  
  // Usually the numerator is LHS + (RHS Div 2); calculate this.
  Value *HalfRHS = Builder.CreateUDiv(RHS, Two, "tmp");
  Value *Numerator = Builder.CreateAdd(LHS, HalfRHS, "tmp");
  
  // Did the calculation overflow?
  Value *Overflowed = Builder.CreateICmpULT(Numerator, HalfRHS, "tmp");
  
  // If so, use (LHS + (RHS Div 2)) - RHS for the numerator instead.
  Value *AltNumerator = Builder.CreateSub(Numerator, RHS, "tmp");
  Numerator = Builder.CreateSelect(Overflowed, AltNumerator, Numerator, "tmp");
  
  // Quotient = Numerator / RHS.
  Value *Quotient = Builder.CreateUDiv(Numerator, RHS, "tmp");
  
  // Return Quotient unless we overflowed, in which case return Quotient + 1.
  return Builder.CreateAdd(Quotient, CastToUIntType(Overflowed, Ty), "rdiv");
}

//===----------------------------------------------------------------------===//
//               ... Inline Assembly and Register Variables ...
//===----------------------------------------------------------------------===//


/// Return a ParamAttrsList for the given function return attributes.
PAListPtr getReturnAttrs(uint16_t attrs) {
  if (attrs == ParamAttr::None)
    return PAListPtr();

  SmallVector<ParamAttrsWithIndex, 8> Attrs;
  Attrs.push_back(ParamAttrsWithIndex::get(0, attrs));
  return PAListPtr::get(Attrs.begin(), Attrs.end());
}

/// Reads from register variables are handled by emitting an inline asm node
/// that copies the value out of the specified register.
Value *TreeToLLVM::EmitReadOfRegisterVariable(tree decl, const MemRef *DestLoc){
  const Type *Ty = ConvertType(TREE_TYPE(decl));
  
  // If there was an error, return something bogus.
  if (ValidateRegisterVariable(decl)) {
    if (Ty->isFirstClassType())
      return UndefValue::get(Ty);
    return 0;   // Just don't copy something into DestLoc.
  }
  
  // Turn this into a 'tmp = call Ty asm "", "={reg}"()'.
  FunctionType *FTy = FunctionType::get(Ty, std::vector<const Type*>(),false);
  
  const char *Name = IDENTIFIER_POINTER(DECL_ASSEMBLER_NAME(decl));
  InlineAsm *IA = InlineAsm::get(FTy, "", "={"+std::string(Name)+"}", false);
  CallInst *Call = Builder.CreateCall(IA, "tmp");
  Call->setParamAttrs(getReturnAttrs(ParamAttr::NoUnwind));
  return Call;
}

/// Stores to register variables are handled by emitting an inline asm node
/// that copies the value into the specified register.
void TreeToLLVM::EmitModifyOfRegisterVariable(tree decl, Value *RHS) {
  // If there was an error, bail out.
  if (ValidateRegisterVariable(decl))
    return;
  
  // Turn this into a 'call void asm sideeffect "", "{reg}"(Ty %RHS)'.
  std::vector<const Type*> ArgTys;
  ArgTys.push_back(ConvertType(TREE_TYPE(decl)));
  FunctionType *FTy = FunctionType::get(Type::VoidTy, ArgTys, false);
  
  const char *Name = IDENTIFIER_POINTER(DECL_ASSEMBLER_NAME(decl));
  InlineAsm *IA = InlineAsm::get(FTy, "", "{"+std::string(Name)+"}", true);
  CallInst *Call = Builder.CreateCall(IA, RHS);
  Call->setParamAttrs(getReturnAttrs(ParamAttr::NoUnwind));
}

/// ConvertInlineAsmStr - Convert the specified inline asm string to an LLVM
/// InlineAsm string.  The GNU style inline asm template string has the
/// following format:
///   %N (for N a digit) means print operand N in usual manner.
///   %=  means a unique number for the inline asm.
///   %lN means require operand N to be a CODE_LABEL or LABEL_REF
///       and print the label name with no punctuation.
///   %cN means require operand N to be a constant
///       and print the constant expression with no punctuation.
///   %aN means expect operand N to be a memory address
///       (not a memory reference!) and print a reference to that address.
///   %nN means expect operand N to be a constant and print a constant
///       expression for minus the value of the operand, with no other
///       punctuation.
/// Other %xN expressions are turned into LLVM ${N:x} operands.
///
static std::string ConvertInlineAsmStr(tree exp, unsigned NumOperands) {
  static unsigned InlineAsmCounter = 0U;
  unsigned InlineAsmNum = InlineAsmCounter++;

  tree str = ASM_STRING(exp);
  if (TREE_CODE(str) == ADDR_EXPR) str = TREE_OPERAND(str, 0);

  // ASM_INPUT_P - This flag is set if this is a non-extended ASM, which means
  // that the asm string should not be interpreted, other than to escape $'s.
  if (ASM_INPUT_P(exp)) {
    const char *InStr = TREE_STRING_POINTER(str);
    std::string Result;
    while (1) {
      switch (*InStr++) {
      case 0: return Result;                 // End of string.
      default: Result += InStr[-1]; break;   // Normal character.
      case '$': Result += "$$"; break;       // Escape '$' characters.
      }
    }
  }
  
  // Expand [name] symbolic operand names.
  str = resolve_asm_operand_names(str, ASM_OUTPUTS(exp), ASM_INPUTS(exp));

  const char *InStr = TREE_STRING_POINTER(str);
  
  std::string Result;
  while (1) {
    switch (*InStr++) {
    case 0: return Result;                 // End of string.
    default: Result += InStr[-1]; break;   // Normal character.
    case '$': Result += "$$"; break;       // Escape '$' characters.
#ifdef ASSEMBLER_DIALECT
    // Note that we can't escape to ${, because that is the syntax for vars.
    case '{': Result += "$("; break;       // Escape '{' character.
    case '}': Result += "$)"; break;       // Escape '}' character.
    case '|': Result += "$|"; break;       // Escape '|' character.
#endif
    case '%':                              // GCC escape character.
      char EscapedChar = *InStr++;
      if (EscapedChar == '%') {            // Escaped '%' character
        Result += '%';
      } else if (EscapedChar == '=') {     // Unique ID for the asm instance.
        Result += utostr(InlineAsmNum);
      }
#ifdef LLVM_ASM_EXTENSIONS
      LLVM_ASM_EXTENSIONS(EscapedChar, InStr, Result)
#endif
      else if (ISALPHA(EscapedChar)) {
        // % followed by a letter and some digits. This outputs an operand in a
        // special way depending on the letter.  We turn this into LLVM ${N:o}
        // syntax.
        char *EndPtr;
        unsigned long OpNum = strtoul(InStr, &EndPtr, 10);
        
        if (InStr == EndPtr) {
          error("%Hoperand number missing after %%-letter",&EXPR_LOCATION(exp));
          return Result;
        } else if (OpNum >= NumOperands) {
          error("%Hoperand number out of range", &EXPR_LOCATION(exp));
          return Result;
        }
        Result += "${" + utostr(OpNum) + ":" + EscapedChar + "}";
        InStr = EndPtr;
      } else if (ISDIGIT(EscapedChar)) {
        char *EndPtr;
        unsigned long OpNum = strtoul(InStr-1, &EndPtr, 10);
        InStr = EndPtr;
        Result += "$" + utostr(OpNum);
#ifdef PRINT_OPERAND_PUNCT_VALID_P
      } else if (PRINT_OPERAND_PUNCT_VALID_P((unsigned char)EscapedChar)) {
        Result += "${:";
        Result += EscapedChar;
        Result += "}";
#endif
      } else {
        output_operand_lossage("invalid %%-code");
      }
      break;
    }
  }
}

/// CanonicalizeConstraint - If we can canonicalize the constraint into
/// something simpler, do so now.  This turns register classes with a single
/// register into the register itself, expands builtin constraints to multiple
/// alternatives, etc.
static std::string CanonicalizeConstraint(const char *Constraint) {
  std::string Result;
  
  // Skip over modifier characters.
  bool DoneModifiers = false;
  while (!DoneModifiers) {
    switch (*Constraint) {
    default: DoneModifiers = true; break;
    case '=': assert(0 && "Should be after '='s");
    case '+': assert(0 && "'+' should already be expanded");
    case '*':
    case '?':
    case '!':
      ++Constraint;
      break;
    case '&':     // Pass earlyclobber to LLVM.
    case '%':     // Pass commutative to LLVM.
      Result += *Constraint++;
      break;
    case '#':  // No constraint letters left.
      return Result;
    }
  }
  
  while (*Constraint) {
    char ConstraintChar = *Constraint++;

    // 'g' is just short-hand for 'imr'.
    if (ConstraintChar == 'g') {
      Result += "imr";
      continue;
    }
  
    // See if this is a regclass constraint.
    unsigned RegClass;
    if (ConstraintChar == 'r')
      // REG_CLASS_FROM_CONSTRAINT doesn't support 'r' for some reason.
      RegClass = GENERAL_REGS;
    else 
      RegClass = REG_CLASS_FROM_CONSTRAINT(Constraint[-1], Constraint-1);
  
    if (RegClass == NO_REGS) {  // not a reg class.
      Result += ConstraintChar;
      continue;
    }

    // Look to see if the specified regclass has exactly one member, and if so,
    // what it is.  Cache this information in AnalyzedRegClasses once computed.
    static std::map<unsigned, int> AnalyzedRegClasses;
  
    std::map<unsigned, int>::iterator I =
      AnalyzedRegClasses.lower_bound(RegClass);
  
    int RegMember;
    if (I != AnalyzedRegClasses.end() && I->first == RegClass) {
      // We've already computed this, reuse value.
      RegMember = I->second;
    } else {
      // Otherwise, scan the regclass, looking for exactly one member.
      RegMember = -1;  // -1 => not a single-register class.
      for (unsigned j = 0; j != FIRST_PSEUDO_REGISTER; ++j)
        if (TEST_HARD_REG_BIT(reg_class_contents[RegClass], j)) {
          if (RegMember == -1) {
            RegMember = j;
          } else {
            RegMember = -1;
            break;
          }
        }
      // Remember this answer for the next query of this regclass.
      AnalyzedRegClasses.insert(I, std::make_pair(RegClass, RegMember));
    }

    // If we found a single register register class, return the register.
    if (RegMember != -1) {
      Result += '{';
      Result += reg_names[RegMember];
      Result += '}';
    } else {
      Result += ConstraintChar;
    }
  }
  
  return Result;
}


Value *TreeToLLVM::EmitASM_EXPR(tree exp) {
  unsigned NumInputs = list_length(ASM_INPUTS(exp));
  unsigned NumOutputs = list_length(ASM_OUTPUTS(exp));
  unsigned NumInOut = 0;
  
  /// Constraints - The output/input constraints, concatenated together in array
  /// form instead of list form.
  const char **Constraints =
    (const char **)alloca((NumOutputs + NumInputs) * sizeof(const char *));
  
  // FIXME: CHECK ALTERNATIVES, something akin to check_operand_nalternatives.
  
  std::vector<Value*> CallOps;
  std::vector<const Type*> CallArgTypes;
  std::string NewAsmStr = ConvertInlineAsmStr(exp, NumOutputs+NumInputs);
  std::string ConstraintStr;
  
  // StoreCallResultAddr - The pointer to store the result of the call through.
  Value *StoreCallResultAddr = 0;
  const Type *CallResultType = Type::VoidTy;
  
  // Process outputs.
  int ValNum = 0;
  for (tree Output = ASM_OUTPUTS(exp); Output; 
       Output = TREE_CHAIN(Output), ++ValNum) {
    tree Operand = TREE_VALUE(Output);
    tree type = TREE_TYPE(Operand);
    // If there's an erroneous arg, emit no insn.
    if (type == error_mark_node) return 0;
    
    // Parse the output constraint.
    const char *Constraint =
      TREE_STRING_POINTER(TREE_VALUE(TREE_PURPOSE(Output)));
    Constraints[ValNum] = Constraint;
    bool IsInOut, AllowsReg, AllowsMem;
    if (!parse_output_constraint(&Constraint, ValNum, NumInputs, NumOutputs,
                                 &AllowsMem, &AllowsReg, &IsInOut))
      return 0;
    
    assert(Constraint[0] == '=' && "Not an output constraint?");

    // Output constraints must be addressible if they aren't simple register
    // constraints (this emits "address of register var" errors, etc).
    if (!AllowsReg && (AllowsMem || IsInOut))
      lang_hooks.mark_addressable(Operand);

    // Count the number of "+" constraints.
    if (IsInOut)
      ++NumInOut, ++NumInputs;

    std::string SimplifiedConstraint;
    // If this output register is pinned to a machine register, use that machine
    // register instead of the specified constraint.
    if (TREE_CODE(Operand) == VAR_DECL && DECL_HARD_REGISTER(Operand)) {
      int RegNum = 
        decode_reg_name(IDENTIFIER_POINTER(DECL_ASSEMBLER_NAME(Operand)));
      if (RegNum >= 0) {
        unsigned RegNameLen = strlen(reg_names[RegNum]);
        char *NewConstraint = (char*)alloca(RegNameLen+4);
        NewConstraint[0] = '=';
        NewConstraint[1] = '{';
        memcpy(NewConstraint+2, reg_names[RegNum], RegNameLen);
        NewConstraint[RegNameLen+2] = '}';
        NewConstraint[RegNameLen+3] = 0;
        SimplifiedConstraint = NewConstraint;
        // We should no longer consider mem constraints.
        AllowsMem = false;
      } else {
        // If we can simplify the constraint into something else, do so now.  This
        // avoids LLVM having to know about all the (redundant) GCC constraints.
        SimplifiedConstraint = CanonicalizeConstraint(Constraint+1);
      }
    } else {
      SimplifiedConstraint = CanonicalizeConstraint(Constraint+1);
    }
    
    LValue Dest = EmitLV(Operand);
    const Type *DestValTy =
      cast<PointerType>(Dest.Ptr->getType())->getElementType();
    
    assert(!Dest.isBitfield() && "Cannot assign into a bitfield!");
    if (ConstraintStr.empty() && !AllowsMem &&  // Reg dest and no output yet?
        DestValTy->isFirstClassType()) {
      assert(StoreCallResultAddr == 0 && "Already have a result val?");
      StoreCallResultAddr = Dest.Ptr;
      ConstraintStr += ",=";
      ConstraintStr += SimplifiedConstraint;
      CallResultType = DestValTy;
    } else {
      ConstraintStr += ",=*";
      ConstraintStr += SimplifiedConstraint;
      CallOps.push_back(Dest.Ptr);
      CallArgTypes.push_back(Dest.Ptr->getType());
    }
  }
  
  // Process inputs.
  for (tree Input = ASM_INPUTS(exp); Input; Input = TREE_CHAIN(Input),++ValNum){
    tree Val = TREE_VALUE(Input);
    tree type = TREE_TYPE(Val);
    // If there's an erroneous arg, emit no insn.
    if (type == error_mark_node) return 0;
    
    const char *Constraint =
      TREE_STRING_POINTER(TREE_VALUE(TREE_PURPOSE(Input)));
    Constraints[ValNum] = Constraint;

    bool AllowsReg, AllowsMem;
    if (!parse_input_constraint(Constraints+ValNum, ValNum-NumOutputs,
                                NumInputs, NumOutputs, NumInOut,
                                Constraints, &AllowsMem, &AllowsReg))
      return 0;
    
    bool isIndirect = false;
    if (AllowsReg || !AllowsMem) {    // Register operand.
      const Type *LLVMTy = ConvertType(type);

      Value *Op = 0;
      if (LLVMTy->isFirstClassType()) {
        if (TREE_CODE(Val)==ADDR_EXPR &&
            TREE_CODE(TREE_OPERAND(Val,0))==LABEL_DECL) {
          // Emit the label, but do not assume it is going to be the target
          // of an indirect branch.
          Op = getLabelDeclBlock(TREE_OPERAND(Val, 0));
        } else
          Op = Emit(Val, 0);
      } else {
        LValue LV = EmitLV(Val);
        assert(!LV.isBitfield() && "Inline asm can't have bitfield operand");
        
        // Structs and unions are permitted here, as long as they're the
        // same size as a register.
        uint64_t TySize = TD.getTypeSizeInBits(LLVMTy);
        if (TySize == 1 || TySize == 8 || TySize == 16 ||
            TySize == 32 || TySize == 64) {
          LLVMTy = IntegerType::get(TySize);
          Op = Builder.CreateLoad(CastToType(Instruction::BitCast, LV.Ptr,
                                             PointerType::getUnqual(LLVMTy)), 
                                             "tmp");
        } else {
          // Otherwise, emit our value as a lvalue and let the codegen deal with
          // it.
          isIndirect = true;
          Op = LV.Ptr;
        }
      }
      
      CallOps.push_back(Op);
      CallArgTypes.push_back(Op->getType());
    } else {                          // Memory operand.
      lang_hooks.mark_addressable(TREE_VALUE(Input));
      isIndirect = true;
      LValue Src = EmitLV(Val);
      assert(!Src.isBitfield() && "Cannot read from a bitfield!");
      CallOps.push_back(Src.Ptr);
      CallArgTypes.push_back(Src.Ptr->getType());
    }
    
    ConstraintStr += ',';
    if (isIndirect)
      ConstraintStr += '*';
    
    // If this output register is pinned to a machine register, use that machine
    // register instead of the specified constraint.
    int RegNum;
    if (TREE_CODE(Val) == VAR_DECL && DECL_HARD_REGISTER(Val) &&
        (RegNum = 
         decode_reg_name(IDENTIFIER_POINTER(DECL_ASSEMBLER_NAME(Val)))) >= 0) {
      ConstraintStr += '{';
      ConstraintStr += reg_names[RegNum];
      ConstraintStr += '}';
    } else {
      // If there is a simpler form for the register constraint, use it.
      std::string Simplified = CanonicalizeConstraint(Constraint);
      ConstraintStr += Simplified;
    }
  }
  
  if (ASM_USES(exp)) {
    // FIXME: Figure out what ASM_USES means.
    error("%Hcode warrior/ms asm not supported yet in %qs", &EXPR_LOCATION(exp),
          TREE_STRING_POINTER(ASM_STRING(exp)));
    return 0;
  }
  
  // Process clobbers.

  // Some targets automatically clobber registers across an asm.
  tree Clobbers = targetm.md_asm_clobbers(ASM_CLOBBERS(exp));
  for (; Clobbers; Clobbers = TREE_CHAIN(Clobbers)) {
    const char *RegName = TREE_STRING_POINTER(TREE_VALUE(Clobbers));
    int RegCode = decode_reg_name(RegName);
    
    switch (RegCode) {
    case -1:     // Nothing specified?
    case -2:     // Invalid.
      error("%Hunknown register name %qs in %<asm%>", &EXPR_LOCATION(exp), 
            RegName);
      return 0;
    case -3:     // cc
      ConstraintStr += ",~{cc}";
      break;
    case -4:     // memory
      ConstraintStr += ",~{memory}";
      break;
    default:     // Normal register name.
      ConstraintStr += ",~{";
      ConstraintStr += reg_names[RegCode];
      ConstraintStr += "}";
      break;
    }
  }
  
  const FunctionType *FTy = 
    FunctionType::get(CallResultType, CallArgTypes, false);
  
  // Remove the leading comma if we have operands.
  if (!ConstraintStr.empty())
    ConstraintStr.erase(ConstraintStr.begin());
  
  // Make sure we're created a valid inline asm expression.
  if (!InlineAsm::Verify(FTy, ConstraintStr)) {
    error("%HInvalid or unsupported inline assembly!", &EXPR_LOCATION(exp));
    return 0;
  }
  
  Value *Asm = InlineAsm::get(FTy, NewAsmStr, ConstraintStr,
                              ASM_VOLATILE_P(exp) || !ASM_OUTPUTS(exp));   
  CallInst *CV = Builder.CreateCall(Asm, CallOps.begin(), CallOps.end(),
                                    StoreCallResultAddr ? "tmp" : "");
  CV->setParamAttrs(getReturnAttrs(ParamAttr::NoUnwind));

  // If the call produces a value, store it into the destination.
  if (StoreCallResultAddr)
    Builder.CreateStore(CV, StoreCallResultAddr);
  
  // Give the backend a chance to upgrade the inline asm to LLVM code.  This
  // handles some common cases that LLVM has intrinsics for, e.g. x86 bswap ->
  // llvm.bswap.
  if (const TargetAsmInfo *TAI = TheTarget->getTargetAsmInfo())
    TAI->ExpandInlineAsm(CV);
  
  return 0;
}

//===----------------------------------------------------------------------===//
//               ... Helpers for Builtin Function Expansion ...
//===----------------------------------------------------------------------===//

Value *TreeToLLVM::BuildVector(const std::vector<Value*> &Ops) {
  assert((Ops.size() & (Ops.size()-1)) == 0 &&
         "Not a power-of-two sized vector!");
  bool AllConstants = true;
  for (unsigned i = 0, e = Ops.size(); i != e && AllConstants; ++i)
    AllConstants &= isa<Constant>(Ops[i]);
    
  // If this is a constant vector, create a ConstantVector.
  if (AllConstants) {
    std::vector<Constant*> CstOps;
    for (unsigned i = 0, e = Ops.size(); i != e; ++i)
      CstOps.push_back(cast<Constant>(Ops[i]));
    return ConstantVector::get(CstOps);
  }
  
  // Otherwise, insertelement the values to build the vector.
  Value *Result = 
    UndefValue::get(VectorType::get(Ops[0]->getType(), Ops.size()));
  
  for (unsigned i = 0, e = Ops.size(); i != e; ++i)
    Result = Builder.CreateInsertElement(Result, Ops[i], 
                                         ConstantInt::get(Type::Int32Ty, i),
                                         "tmp");
  
  return Result;
}

/// BuildVector - This varargs function builds a literal vector ({} syntax) with
/// the specified null-terminated list of elements.  The elements must be all
/// the same element type and there must be a power of two of them.
Value *TreeToLLVM::BuildVector(Value *Elt, ...) {
  std::vector<Value*> Ops;
  va_list VA;
  va_start(VA, Elt);
  
  Ops.push_back(Elt);
  while (Value *Arg = va_arg(VA, Value *))
    Ops.push_back(Arg);
  va_end(VA);
  
  return BuildVector(Ops);
}

/// BuildVectorShuffle - Given two vectors and a variable length list of int
/// constants, create a shuffle of the elements of the inputs, where each dest
/// is specified by the indexes.  The int constant list must be as long as the
/// number of elements in the input vector.
///
/// Undef values may be specified by passing in -1 as the result value.
///
Value *TreeToLLVM::BuildVectorShuffle(Value *InVec1, Value *InVec2, ...) {
  assert(isa<VectorType>(InVec1->getType()) && 
         InVec1->getType() == InVec2->getType() && "Invalid shuffle!");
  unsigned NumElements = cast<VectorType>(InVec1->getType())->getNumElements();

  // Get all the indexes from varargs.
  std::vector<Constant*> Idxs;
  va_list VA;
  va_start(VA, InVec2);
  for (unsigned i = 0; i != NumElements; ++i) {
    int idx = va_arg(VA, int);
    if (idx == -1)
      Idxs.push_back(UndefValue::get(Type::Int32Ty));
    else {
      assert((unsigned)idx < 2*NumElements && "Element index out of range!");
      Idxs.push_back(ConstantInt::get(Type::Int32Ty, idx));
    }
  }
  va_end(VA);

  // Turn this into the appropriate shuffle operation.
  return Builder.CreateShuffleVector(InVec1, InVec2, ConstantVector::get(Idxs),
                                     "tmp");
}

//===----------------------------------------------------------------------===//
//                     ... Builtin Function Expansion ...
//===----------------------------------------------------------------------===//

/// EmitFrontendExpandedBuiltinCall - For MD builtins that do not have a
/// directly corresponding LLVM intrinsic, we allow the target to do some amount
/// of lowering.  This allows us to avoid having intrinsics for operations that
/// directly correspond to LLVM constructs.
///
/// This method returns true if the builtin is handled, otherwise false.
///
bool TreeToLLVM::EmitFrontendExpandedBuiltinCall(tree exp, tree fndecl,
                                                 const MemRef *DestLoc,
                                                 Value *&Result){
#ifdef LLVM_TARGET_INTRINSIC_LOWER
  // Get the result type and oeprand line in an easy to consume format.
  const Type *ResultType = ConvertType(TREE_TYPE(TREE_TYPE(fndecl)));
  std::vector<Value*> Operands;
  for (tree Op = TREE_OPERAND(exp, 1); Op; Op = TREE_CHAIN(Op))
    Operands.push_back(Emit(TREE_VALUE(Op), 0));
  
  unsigned FnCode = DECL_FUNCTION_CODE(fndecl);
  return LLVM_TARGET_INTRINSIC_LOWER(exp, FnCode, DestLoc, Result, ResultType,
                                     Operands);
#endif
  return false;
}

/// TargetBuiltinCache - A cache of builtin intrisics indexed by the GCC builtin
/// number.
static std::vector<Constant*> TargetBuiltinCache;

void clearTargetBuiltinCache() {
  TargetBuiltinCache.clear();
}

/// EmitBuiltinCall - exp is a call to fndecl, a builtin function.  Try to emit
/// the call in a special way, setting Result to the scalar result if necessary.
/// If we can't handle the builtin, return false, otherwise return true.
bool TreeToLLVM::EmitBuiltinCall(tree exp, tree fndecl,
                                 const MemRef *DestLoc, Value *&Result) {
  if (DECL_BUILT_IN_CLASS(fndecl) == BUILT_IN_MD) {
    unsigned FnCode = DECL_FUNCTION_CODE(fndecl);
    if (TargetBuiltinCache.size() <= FnCode)
      TargetBuiltinCache.resize(FnCode+1);
    
    // If we haven't converted this intrinsic over yet, do so now.
    if (TargetBuiltinCache[FnCode] == 0) {
      const char *TargetPrefix = "";
#ifdef LLVM_TARGET_INTRINSIC_PREFIX
      TargetPrefix = LLVM_TARGET_INTRINSIC_PREFIX;
#endif
      // If this builtin directly corresponds to an LLVM intrinsic, get the
      // IntrinsicID now.
      const char *BuiltinName = IDENTIFIER_POINTER(DECL_NAME(fndecl));
      Intrinsic::ID IntrinsicID;
#define GET_LLVM_INTRINSIC_FOR_GCC_BUILTIN
#include "llvm/Intrinsics.gen"
#undef GET_LLVM_INTRINSIC_FOR_GCC_BUILTIN
      
      if (IntrinsicID == Intrinsic::not_intrinsic) {
        if (EmitFrontendExpandedBuiltinCall(exp, fndecl, DestLoc, Result))
          return true;
        
        std::cerr << "TYPE: " << *ConvertType(TREE_TYPE(fndecl)) << "\n";
        error("%Hunsupported target builtin %<%s%> used", &EXPR_LOCATION(exp),
              BuiltinName);
        const Type *ResTy = ConvertType(TREE_TYPE(exp));
        if (ResTy->isFirstClassType())
          Result = UndefValue::get(ResTy);
        return true;
      }
      
      // Finally, map the intrinsic ID back to a name.
      TargetBuiltinCache[FnCode] = 
        Intrinsic::getDeclaration(TheModule, IntrinsicID);
    }

    Result = EmitCallOf(TargetBuiltinCache[FnCode], exp, DestLoc, PAListPtr());
    return true;
  }
  
  switch (DECL_FUNCTION_CODE(fndecl)) {
  default: return false;
  // Varargs builtins.
  case BUILT_IN_VA_START:
  case BUILT_IN_STDARG_START:   return EmitBuiltinVAStart(exp);
  case BUILT_IN_VA_END:         return EmitBuiltinVAEnd(exp);
  case BUILT_IN_VA_COPY:        return EmitBuiltinVACopy(exp);
  case BUILT_IN_CONSTANT_P:     return EmitBuiltinConstantP(exp, Result);
  case BUILT_IN_ALLOCA:         return EmitBuiltinAlloca(exp, Result);
  case BUILT_IN_EXTEND_POINTER: return EmitBuiltinExtendPointer(exp, Result);
  case BUILT_IN_EXPECT:         return EmitBuiltinExpect(exp, DestLoc, Result);
  case BUILT_IN_MEMCPY:         return EmitBuiltinMemCopy(exp, Result, false);
  case BUILT_IN_MEMMOVE:        return EmitBuiltinMemCopy(exp, Result, true);
  case BUILT_IN_MEMSET:         return EmitBuiltinMemSet(exp, Result);
  case BUILT_IN_BZERO:          return EmitBuiltinBZero(exp, Result);
  case BUILT_IN_PREFETCH:       return EmitBuiltinPrefetch(exp);
  case BUILT_IN_FRAME_ADDRESS:  return EmitBuiltinReturnAddr(exp, Result,true);
  case BUILT_IN_RETURN_ADDRESS: return EmitBuiltinReturnAddr(exp, Result,false);
  case BUILT_IN_STACK_SAVE:     return EmitBuiltinStackSave(exp, Result);
  case BUILT_IN_STACK_RESTORE:  return EmitBuiltinStackRestore(exp);
  case BUILT_IN_EXTRACT_RETURN_ADDR:
   return EmitBuiltinExtractReturnAddr(exp, Result);
  case BUILT_IN_FROB_RETURN_ADDR:
   return EmitBuiltinFrobReturnAddr(exp, Result);
  case BUILT_IN_INIT_TRAMPOLINE:
    return EmitBuiltinInitTrampoline(exp, Result);

  // Builtins used by the exception handling runtime.
  case BUILT_IN_DWARF_CFA:
    return EmitBuiltinDwarfCFA(exp, Result);
#ifdef DWARF2_UNWIND_INFO
  case BUILT_IN_DWARF_SP_COLUMN:
    return EmitBuiltinDwarfSPColumn(exp, Result);
  case BUILT_IN_INIT_DWARF_REG_SIZES:
    return EmitBuiltinInitDwarfRegSizes(exp, Result);
#endif
  case BUILT_IN_EH_RETURN:
    return EmitBuiltinEHReturn(exp, Result);
#ifdef EH_RETURN_DATA_REGNO
  case BUILT_IN_EH_RETURN_DATA_REGNO:
    return EmitBuiltinEHReturnDataRegno(exp, Result);
#endif
  case BUILT_IN_UNWIND_INIT:
    return EmitBuiltinUnwindInit(exp, Result);

  // Unary bit counting intrinsics.
  // NOTE: do not merge these case statements.  That will cause the memoized 
  // Function* to be incorrectly shared across the different typed functions.
  case BUILT_IN_CLZ:       // These GCC builtins always return int.
  case BUILT_IN_CLZL:
  case BUILT_IN_CLZLL: {
    Value *Amt = Emit(TREE_VALUE(TREE_OPERAND(exp, 1)), 0);
    EmitBuiltinUnaryIntOp(Amt, Result, Intrinsic::ctlz); 
    const Type *DestTy = ConvertType(TREE_TYPE(exp));
    if (Result->getType() != DestTy)
      Result = Builder.CreateIntCast(Result, DestTy, "cast");
    return true;
  }
  case BUILT_IN_CTZ:       // These GCC builtins always return int.
  case BUILT_IN_CTZL:
  case BUILT_IN_CTZLL: {
    Value *Amt = Emit(TREE_VALUE(TREE_OPERAND(exp, 1)), 0);
    EmitBuiltinUnaryIntOp(Amt, Result, Intrinsic::cttz);
    const Type *DestTy = ConvertType(TREE_TYPE(exp));
    if (Result->getType() != DestTy)
      Result = Builder.CreateIntCast(Result, DestTy, "cast");
    return true;
  }
  case BUILT_IN_POPCOUNT:  // These GCC builtins always return int.
  case BUILT_IN_POPCOUNTL:
  case BUILT_IN_POPCOUNTLL: {
    Value *Amt = Emit(TREE_VALUE(TREE_OPERAND(exp, 1)), 0);
    EmitBuiltinUnaryIntOp(Amt, Result, Intrinsic::ctpop); 
    const Type *DestTy = ConvertType(TREE_TYPE(exp));
    if (Result->getType() != DestTy)
      Result = Builder.CreateIntCast(Result, DestTy, "cast");
    return true;
  }
  case BUILT_IN_SQRT: 
  case BUILT_IN_SQRTF:
  case BUILT_IN_SQRTL:
    // If errno math has been disabled, expand these to llvm.sqrt calls.
    if (!flag_errno_math) {
      Result = EmitBuiltinSQRT(exp);
      Result = CastToFPType(Result, ConvertType(TREE_TYPE(exp)));
      return true; 
    }
    break;
  case BUILT_IN_POWI:
  case BUILT_IN_POWIF:
  case BUILT_IN_POWIL:
    Result = EmitBuiltinPOWI(exp);
    return true;
  case BUILT_IN_FFS:  // These GCC builtins always return int.
  case BUILT_IN_FFSL:
  case BUILT_IN_FFSLL: {      // FFS(X) -> (x == 0 ? 0 : CTTZ(x)+1)
    // The argument and return type of cttz should match the argument type of
    // the ffs, but should ignore the return type of ffs.
    Value *Amt = Emit(TREE_VALUE(TREE_OPERAND(exp, 1)), 0);
    EmitBuiltinUnaryIntOp(Amt, Result, Intrinsic::cttz); 
    Result = Builder.CreateAdd(Result, ConstantInt::get(Result->getType(), 1),
                               "tmp");
    Value *Cond =
      Builder.CreateICmpEQ(Amt, Constant::getNullValue(Amt->getType()), "tmp");
    Result = Builder.CreateSelect(Cond,
                                  Constant::getNullValue(Result->getType()),
                                  Result, "tmp");
    return true;
  }

  // Convert annotation built-in to llvm.annotation intrinsic.
  case BUILT_IN_ANNOTATION: {
      
    // Get file and line number
    location_t locus = EXPR_LOCATION (exp);
    Constant *lineNo = ConstantInt::get(Type::Int32Ty, locus.line);
    Constant *file = ConvertMetadataStringToGV(locus.file);
    const Type *SBP= PointerType::getUnqual(Type::Int8Ty);
    file = ConstantExpr::getBitCast(file, SBP);
    
    // Get arguments.
    tree arglist = TREE_OPERAND(exp, 1);
    Value *ExprVal = Emit(TREE_VALUE(arglist), 0);
    const Type *Ty = ExprVal->getType();
    Value *StrVal = Emit(TREE_VALUE(TREE_CHAIN(arglist)), 0);
    
    SmallVector<Value *, 4> Args;
    Args.push_back(ExprVal);
    Args.push_back(StrVal);
    Args.push_back(file);
    Args.push_back(lineNo);
    
    assert(Ty && "llvm.annotation arg type may not be null");
    Result = Builder.CreateCall(Intrinsic::getDeclaration(TheModule, 
                                                          Intrinsic::annotation, 
                                                          &Ty, 
                                                          1),
                                Args.begin(), Args.end());
    return true;
  }
   case BUILT_IN_TRAP:
     Builder.CreateCall(Intrinsic::getDeclaration(TheModule, Intrinsic::trap));
     // Emit an explicit unreachable instruction.
     Builder.CreateUnreachable();
     EmitBlock(new BasicBlock(""));
     return true;

#if 1  // FIXME: Should handle these GCC extensions eventually.
    case BUILT_IN_APPLY_ARGS:
    case BUILT_IN_APPLY:
    case BUILT_IN_RETURN:
    case BUILT_IN_SAVEREGS:
    case BUILT_IN_ARGS_INFO:
    case BUILT_IN_NEXT_ARG:
    case BUILT_IN_CLASSIFY_TYPE:
    case BUILT_IN_AGGREGATE_INCOMING_ADDRESS:
    case BUILT_IN_SETJMP:
    case BUILT_IN_LONGJMP:
    case BUILT_IN_UPDATE_SETJMP_BUF:

    // FIXME: HACK: Just ignore these.
    {
      const Type *Ty = ConvertType(TREE_TYPE(exp));
      if (Ty != Type::VoidTy)
        Result = Constant::getNullValue(Ty);
      return true;
    }
#endif  // FIXME: Should handle these GCC extensions eventually.
  }
  return false;
}

bool TreeToLLVM::EmitBuiltinUnaryIntOp(Value *InVal, Value *&Result,
                                       Intrinsic::ID Id) {
  // The intrinsic might be overloaded in which case the argument is of
  // varying type. Make sure that we specify the actual type for "iAny" 
  // by passing it as the 3rd and 4th parameters. This isn't needed for
  // most intrinsics, but is needed for ctpop, cttz, ctlz.
  const Type *Ty = InVal->getType();
  Result = Builder.CreateCall(Intrinsic::getDeclaration(TheModule, Id, &Ty, 1),
                                                        InVal, "tmp");
  return true;
}

Value *TreeToLLVM::EmitBuiltinUnaryFPOp(Value *Amt, const char *F32Name,
                                        const char *F64Name, 
                                        const char *LongDoubleName) {
  const char *Name = 0;
  
  switch (Amt->getType()->getTypeID()) {
  default: assert(0 && "Unknown FP type!");
  case Type::FloatTyID:  Name = F32Name; break;
  case Type::DoubleTyID: Name = F64Name; break;
  case Type::X86_FP80TyID:
  case Type::PPC_FP128TyID:
  case Type::FP128TyID: Name = LongDoubleName; break;
  }
  
  return Builder.CreateCall(cast<Function>(
    TheModule->getOrInsertFunction(Name, Amt->getType(), Amt->getType(), NULL)),
                            Amt, "tmp");
}

Value *TreeToLLVM::EmitBuiltinSQRT(tree exp) {
  Value *Amt = Emit(TREE_VALUE(TREE_OPERAND(exp, 1)), 0);
  Intrinsic::ID Id = Intrinsic::not_intrinsic;
  const Type* Ty = Amt->getType();
  
  return Builder.CreateCall(Intrinsic::getDeclaration(TheModule, 
                                                      Intrinsic::sqrt, &Ty, 1),
                            Amt, "tmp");
}

Value *TreeToLLVM::EmitBuiltinPOWI(tree exp) {
  tree ArgList = TREE_OPERAND (exp, 1);
  if (!validate_arglist(ArgList, REAL_TYPE, INTEGER_TYPE, VOID_TYPE))
    return 0;

  Value *Val = Emit(TREE_VALUE(ArgList), 0);
  Value *Pow = Emit(TREE_VALUE(TREE_CHAIN(ArgList)), 0);
  const Type *Ty = Val->getType();
  Pow = CastToSIntType(Pow, Type::Int32Ty);

  SmallVector<Value *,2> Args;
  Args.push_back(Val);
  Args.push_back(Pow);
  return Builder.CreateCall(Intrinsic::getDeclaration(TheModule, 
                                                      Intrinsic::powi, &Ty, 1),
                            Args.begin(), Args.end(), "tmp");
}


bool TreeToLLVM::EmitBuiltinConstantP(tree exp, Value *&Result) {
  Result = Constant::getNullValue(ConvertType(TREE_TYPE(exp)));
  return true;
}

bool TreeToLLVM::EmitBuiltinExtendPointer(tree exp, Value *&Result) {
  tree arglist = TREE_OPERAND(exp, 1);
  Value *Amt = Emit(TREE_VALUE(arglist), 0);
  bool AmtIsSigned = !TYPE_UNSIGNED(TREE_TYPE(TREE_VALUE(arglist)));
  bool ExpIsSigned = !TYPE_UNSIGNED(TREE_TYPE(exp));
  Result = CastToAnyType(Amt, AmtIsSigned, ConvertType(TREE_TYPE(exp)), 
                         ExpIsSigned);
  return true;
}

/// EmitBuiltinMemCopy - Emit an llvm.memcpy or llvm.memmove intrinsic, 
/// depending on the value of isMemMove.
bool TreeToLLVM::EmitBuiltinMemCopy(tree_node *exp, Value *&Result, 
                                    bool isMemMove) {
  tree arglist = TREE_OPERAND(exp, 1);
  if (!validate_arglist(arglist, POINTER_TYPE, POINTER_TYPE, 
                        INTEGER_TYPE, VOID_TYPE))
    return false;
  
  tree Dst = TREE_VALUE(arglist);
  tree Src = TREE_VALUE(TREE_CHAIN(arglist));
  unsigned SrcAlign = get_pointer_alignment(Src, BIGGEST_ALIGNMENT);
  unsigned DstAlign = get_pointer_alignment(Dst, BIGGEST_ALIGNMENT);
  
  // If the DST or SRC pointers are not pointer type, do this out of line.
  if (SrcAlign == 0 || DstAlign == 0) return false;

  Value *DstV = Emit(Dst, 0);
  Value *SrcV = Emit(Src, 0);
  Value *Len = Emit(TREE_VALUE(TREE_CHAIN(TREE_CHAIN(arglist))), 0);
  if (isMemMove)
    EmitMemMove(DstV, SrcV, Len, std::min(SrcAlign, DstAlign)/8);
  else
    EmitMemCpy(DstV, SrcV, Len, std::min(SrcAlign, DstAlign)/8);
  Result = DstV;
  return true;
}

bool TreeToLLVM::EmitBuiltinMemSet(tree_node *exp, Value *&Result) {
  tree arglist = TREE_OPERAND(exp, 1);
  if (!validate_arglist(arglist, POINTER_TYPE, INTEGER_TYPE, 
                        INTEGER_TYPE, VOID_TYPE))
    return false;
  
  tree Dst = TREE_VALUE(arglist);
  unsigned DstAlign = get_pointer_alignment(Dst, BIGGEST_ALIGNMENT);
  
  // If the DST pointer is not a pointer type, do this out of line.
  if (DstAlign == 0) return false;
  
  Value *DstV = Emit(Dst, 0);
  Value *Val = Emit(TREE_VALUE(TREE_CHAIN(arglist)), 0);
  Value *Len = Emit(TREE_VALUE(TREE_CHAIN(TREE_CHAIN(arglist))), 0);
  EmitMemSet(DstV, Val, Len, DstAlign/8);
  Result = DstV;
  return true;
}

bool TreeToLLVM::EmitBuiltinBZero(tree_node *exp, Value *&Result) {
  tree arglist = TREE_OPERAND(exp, 1);
  if (!validate_arglist(arglist, POINTER_TYPE, INTEGER_TYPE, VOID_TYPE))
    return false;
  
  tree Dst = TREE_VALUE(arglist);
  unsigned DstAlign = get_pointer_alignment(Dst, BIGGEST_ALIGNMENT);
  
  // If the DST pointer is not a pointer type, do this out of line.
  if (DstAlign == 0) return false;
  
  Value *DstV = Emit(Dst, 0);
  Value *Val = Constant::getNullValue(Type::Int32Ty);
  Value *Len = Emit(TREE_VALUE(TREE_CHAIN(arglist)), 0);
  EmitMemSet(DstV, Val, Len, DstAlign/8);
  return true;
}

bool TreeToLLVM::EmitBuiltinPrefetch(tree exp) {
  tree arglist = TREE_OPERAND(exp, 1);
  if (!validate_arglist(arglist, POINTER_TYPE, 0))
    return false;

  Value *Ptr = Emit(TREE_VALUE(arglist), 0);
  Value *ReadWrite = 0;
  Value *Locality = 0;
  
  if (TREE_CHAIN(arglist)) { // Args 1/2 are optional
    ReadWrite = Emit(TREE_VALUE(TREE_CHAIN(arglist)), 0);
    if (!isa<ConstantInt>(ReadWrite)) {
      error("second argument to %<__builtin_prefetch%> must be a constant");
      ReadWrite = 0;
    } else if (cast<ConstantInt>(ReadWrite)->getZExtValue() > 1) {
      warning ("invalid second argument to %<__builtin_prefetch%>;"
	       " using zero");
      ReadWrite = 0;
    } else {
      ReadWrite = ConstantExpr::getIntegerCast(cast<Constant>(ReadWrite),
                                               Type::Int32Ty, false);
    }
    
    if (TREE_CHAIN(TREE_CHAIN(arglist))) {
      Locality = Emit(TREE_VALUE(TREE_CHAIN(TREE_CHAIN(arglist))), 0);
      if (!isa<ConstantInt>(Locality)) {
        error("third argument to %<__builtin_prefetch%> must be a constant");
        Locality = 0;
      } else if (cast<ConstantInt>(Locality)->getZExtValue() > 3) {
        warning("invalid third argument to %<__builtin_prefetch%>; using 3");
        Locality = 0;
      } else {
        Locality = ConstantExpr::getIntegerCast(cast<Constant>(Locality),
                                                Type::Int32Ty, false);
      }
    }
  }
  
  // Default to highly local read.
  if (ReadWrite == 0)
    ReadWrite = Constant::getNullValue(Type::Int32Ty);
  if (Locality == 0)
    Locality = ConstantInt::get(Type::Int32Ty, 3);
  
  Ptr = CastToType(Instruction::BitCast, Ptr, 
                   PointerType::getUnqual(Type::Int8Ty));
  
  Value *Ops[3] = { Ptr, ReadWrite, Locality };
  Builder.CreateCall(Intrinsic::getDeclaration(TheModule, Intrinsic::prefetch),
                     Ops, Ops+3);
  return true;
}

/// EmitBuiltinReturnAddr - Emit an llvm.returnaddress or llvm.frameaddress
/// instruction, depending on whether isFrame is true or not.
bool TreeToLLVM::EmitBuiltinReturnAddr(tree exp, Value *&Result, bool isFrame) {
  tree arglist = TREE_OPERAND(exp, 1);
  if (!validate_arglist(arglist, INTEGER_TYPE, VOID_TYPE))
    return false;
  
  ConstantInt *Level = dyn_cast<ConstantInt>(Emit(TREE_VALUE(arglist), 0));
  if (!Level) {
    if (isFrame)
      error("invalid argument to %<__builtin_frame_address%>");
    else
      error("invalid argument to %<__builtin_return_address%>");
    return false;
  }
  
  Intrinsic::ID IID =
    !isFrame ? Intrinsic::returnaddress : Intrinsic::frameaddress;
  Result = Builder.CreateCall(Intrinsic::getDeclaration(TheModule, IID),
                              Level, "tmp");
  Result = CastToType(Instruction::BitCast, Result, TREE_TYPE(exp));
  return true;
}

bool TreeToLLVM::EmitBuiltinExtractReturnAddr(tree exp, Value *&Result) {
  tree arglist = TREE_OPERAND(exp, 1);

  Value *Ptr = Emit(TREE_VALUE(arglist), 0);

  // FIXME: Actually we should do something like this:
  //
  // Result = (Ptr & MASK_RETURN_ADDR) + RETURN_ADDR_OFFSET, if mask and
  // offset are defined. This seems to be needed for: ARM, MIPS, Sparc.
  // Unfortunately, these constants are defined as RTL expressions and
  // should be handled separately.
  
  Result = CastToType(Instruction::BitCast, Ptr, 
                      PointerType::getUnqual(Type::Int8Ty));

  return true;
}

bool TreeToLLVM::EmitBuiltinFrobReturnAddr(tree exp, Value *&Result) {
  tree arglist = TREE_OPERAND(exp, 1);

  Value *Ptr = Emit(TREE_VALUE(arglist), 0);

  // FIXME: Actually we should do something like this:
  //
  // Result = Ptr - RETURN_ADDR_OFFSET, if offset is defined. This seems to be
  // needed for: MIPS, Sparc.  Unfortunately, these constants are defined
  // as RTL expressions and should be handled separately.
  
  Result = CastToType(Instruction::BitCast, Ptr, 
                      PointerType::getUnqual(Type::Int8Ty));

  return true;
}

bool TreeToLLVM::EmitBuiltinStackSave(tree exp, Value *&Result) {
  tree arglist = TREE_OPERAND(exp, 1);
  if (!validate_arglist(arglist, VOID_TYPE))
    return false;
  
  Result = Builder.CreateCall(Intrinsic::getDeclaration(TheModule,
                                                        Intrinsic::stacksave),
                              "tmp");
  return true;
}


// Builtins used by the exception handling runtime.

// On most machines, the CFA coincides with the first incoming parm.
#ifndef ARG_POINTER_CFA_OFFSET
#define ARG_POINTER_CFA_OFFSET(FNDECL) FIRST_PARM_OFFSET (FNDECL)
#endif

// The mapping from gcc register number to DWARF 2 CFA column number.  By
// default, we just provide columns for all registers.
#ifndef DWARF_FRAME_REGNUM
#define DWARF_FRAME_REGNUM(REG) DBX_REGISTER_NUMBER (REG)
#endif

// Map register numbers held in the call frame info that gcc has
// collected using DWARF_FRAME_REGNUM to those that should be output in
// .debug_frame and .eh_frame.
#ifndef DWARF2_FRAME_REG_OUT
#define DWARF2_FRAME_REG_OUT(REGNO, FOR_EH) (REGNO)
#endif

/* Registers that get partially clobbered by a call in a given mode.
   These must not be call used registers.  */
#ifndef HARD_REGNO_CALL_PART_CLOBBERED
#define HARD_REGNO_CALL_PART_CLOBBERED(REGNO, MODE) 0
#endif

bool TreeToLLVM::EmitBuiltinDwarfCFA(tree exp, Value *&Result) {
  if (!validate_arglist(TREE_OPERAND(exp, 1), VOID_TYPE))
    return false;

  int cfa_offset = ARG_POINTER_CFA_OFFSET(0);

  Result = Builder.CreateCall(Intrinsic::getDeclaration(TheModule,
                                                      Intrinsic::eh_dwarf_cfa),
                              ConstantInt::get(Type::Int32Ty, cfa_offset));

  return true;
}

bool TreeToLLVM::EmitBuiltinDwarfSPColumn(tree exp, Value *&Result) {
  if (!validate_arglist(TREE_OPERAND(exp, 1), VOID_TYPE))
    return false;

  unsigned int dwarf_regnum = DWARF_FRAME_REGNUM(STACK_POINTER_REGNUM);
  Result = ConstantInt::get(ConvertType(TREE_TYPE(exp)), dwarf_regnum);

  return true;
}

bool TreeToLLVM::EmitBuiltinEHReturnDataRegno(tree exp, Value *&Result) {
#ifdef EH_RETURN_DATA_REGNO
  tree arglist = TREE_OPERAND(exp, 1);

  if (!validate_arglist(arglist, INTEGER_TYPE, VOID_TYPE))
    return false;

  tree which = TREE_VALUE (arglist);
  unsigned HOST_WIDE_INT iwhich;

  if (TREE_CODE (which) != INTEGER_CST) {
    error ("argument of %<__builtin_eh_return_regno%> must be constant");
    return false;
  }

  iwhich = tree_low_cst (which, 1);
  iwhich = EH_RETURN_DATA_REGNO (iwhich);
  if (iwhich == INVALID_REGNUM)
    return false;

  iwhich = DWARF_FRAME_REGNUM (iwhich);

  Result = ConstantInt::get(ConvertType(TREE_TYPE(exp)), iwhich);
#endif

  return true;
}

bool TreeToLLVM::EmitBuiltinEHReturn(tree exp, Value *&Result) {
  tree arglist = TREE_OPERAND(exp, 1);

  if (!validate_arglist(arglist, INTEGER_TYPE, POINTER_TYPE, VOID_TYPE))
    return false;

  Value *Offset = Emit(TREE_VALUE(arglist), 0);
  Value *Handler = Emit(TREE_VALUE(TREE_CHAIN(arglist)), 0);
  Offset = Builder.CreateIntCast(Offset, Type::Int32Ty, true, "tmp");
  Handler = CastToType(Instruction::BitCast, Handler,
                       PointerType::getUnqual(Type::Int8Ty));

  SmallVector<Value *, 2> Args;
  Args.push_back(Offset);
  Args.push_back(Handler);
  Builder.CreateCall(Intrinsic::getDeclaration(TheModule,
                                               Intrinsic::eh_return),
                     Args.begin(), Args.end());
  Result = Builder.CreateUnreachable();
  EmitBlock(new BasicBlock(""));

  return true;
}

bool TreeToLLVM::EmitBuiltinInitDwarfRegSizes(tree exp, Value *&Result) {
#ifdef DWARF2_UNWIND_INFO
  unsigned int i;
  bool wrote_return_column = false;
  static bool reg_modes_initialized = false;

  tree arglist = TREE_OPERAND(exp, 1);
  if (!validate_arglist(arglist, POINTER_TYPE, VOID_TYPE))
    return false;

  if (!reg_modes_initialized) {
    init_reg_modes_once();
    reg_modes_initialized = true;
  }

  Value *Addr = BitCastToType(Emit(TREE_VALUE(arglist), 0),
                              PointerType::getUnqual(Type::Int8Ty));
  Constant *Size, *Idx;

  for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) {
    int rnum = DWARF2_FRAME_REG_OUT (DWARF_FRAME_REGNUM (i), 1);

    if (rnum < DWARF_FRAME_REGISTERS) {
      enum machine_mode save_mode = reg_raw_mode[i];
      HOST_WIDE_INT size;

      if (HARD_REGNO_CALL_PART_CLOBBERED (i, save_mode))
        save_mode = choose_hard_reg_mode (i, 1, true);
      if (DWARF_FRAME_REGNUM (i) == DWARF_FRAME_RETURN_COLUMN) {
        if (save_mode == VOIDmode)
          continue;
        wrote_return_column = true;
      }
      size = GET_MODE_SIZE (save_mode);
      if (rnum < 0)
        continue;

      Size = ConstantInt::get(Type::Int8Ty, size);
      Idx  = ConstantInt::get(Type::Int32Ty, rnum);
      Builder.CreateStore(Size, Builder.CreateGEP(Addr, Idx, "tmp"), false);
    }
  }

  if (!wrote_return_column) {
    Size = ConstantInt::get(Type::Int8Ty, GET_MODE_SIZE (Pmode));
    Idx  = ConstantInt::get(Type::Int32Ty, DWARF_FRAME_RETURN_COLUMN);
    Builder.CreateStore(Size, Builder.CreateGEP(Addr, Idx, "tmp"), false);
  }

#ifdef DWARF_ALT_FRAME_RETURN_COLUMN
  Size = ConstantInt::get(Type::Int8Ty, GET_MODE_SIZE (Pmode));
  Idx  = ConstantInt::get(Type::Int32Ty, DWARF_ALT_FRAME_RETURN_COLUMN);
  Builder.CreateStore(Size, Builder.CreateGEP(Addr, Idx, "tmp"), false);
#endif

#endif /* DWARF2_UNWIND_INFO */

  // TODO: the RS6000 target needs extra initialization [gcc changeset 122468].

  return true;
}

bool TreeToLLVM::EmitBuiltinUnwindInit(tree exp, Value *&Result) {
  if (!validate_arglist(TREE_OPERAND(exp, 1), VOID_TYPE))
    return false;

  Result = Builder.CreateCall(Intrinsic::getDeclaration(TheModule,
                                                    Intrinsic::eh_unwind_init));

  return true;
}

bool TreeToLLVM::EmitBuiltinStackRestore(tree exp) {
  tree arglist = TREE_OPERAND(exp, 1);
  if (!validate_arglist(arglist, POINTER_TYPE, VOID_TYPE))
    return false;
  
  Value *Ptr = Emit(TREE_VALUE(arglist), 0);
  Ptr = CastToType(Instruction::BitCast, Ptr,     
                   PointerType::getUnqual(Type::Int8Ty));

  Builder.CreateCall(Intrinsic::getDeclaration(TheModule,
                                               Intrinsic::stackrestore), Ptr);
  return true;
}


bool TreeToLLVM::EmitBuiltinAlloca(tree exp, Value *&Result) {
  tree arglist = TREE_OPERAND(exp, 1);
  if (!validate_arglist(arglist, INTEGER_TYPE, VOID_TYPE))
    return false;
  Value *Amt = Emit(TREE_VALUE(arglist), 0);
  Amt = CastToSIntType(Amt, Type::Int32Ty);
  Result = Builder.CreateAlloca(Type::Int8Ty, Amt, "tmp");
  return true;
}

bool TreeToLLVM::EmitBuiltinExpect(tree exp, const MemRef *DestLoc,
                                   Value *&Result) {
  // Ignore the hint for now, just expand the expr.  This is safe, but not
  // optimal.
  tree arglist = TREE_OPERAND(exp, 1);
  if (arglist == NULL_TREE || TREE_CHAIN(arglist) == NULL_TREE)
    return true;
  Result = Emit(TREE_VALUE(arglist), DestLoc);
  return true;
}

bool TreeToLLVM::EmitBuiltinVAStart(tree exp) {
  tree arglist = TREE_OPERAND(exp, 1);
  tree fntype = TREE_TYPE(current_function_decl);
  
  if (TYPE_ARG_TYPES(fntype) == 0 ||
      (TREE_VALUE(tree_last(TYPE_ARG_TYPES(fntype))) == void_type_node)) {
    error("`va_start' used in function with fixed args");
    return true;
  }
  
  tree last_parm = tree_last(DECL_ARGUMENTS(current_function_decl));
  tree chain = TREE_CHAIN(arglist);

  // Check for errors.
  if (fold_builtin_next_arg (chain))
    return true;
  
  tree arg = TREE_VALUE(chain);
  
  Value *ArgVal = Emit(TREE_VALUE(arglist), 0);

  Constant *llvm_va_start_fn = Intrinsic::getDeclaration(TheModule,
                                                         Intrinsic::vastart);
  const Type *FTy =
    cast<PointerType>(llvm_va_start_fn->getType())->getElementType();
  ArgVal = CastToType(Instruction::BitCast, ArgVal,
                      PointerType::getUnqual(Type::Int8Ty));
  Builder.CreateCall(llvm_va_start_fn, ArgVal);
  return true;
}

bool TreeToLLVM::EmitBuiltinVAEnd(tree exp) {
  Value *Arg = Emit(TREE_VALUE(TREE_OPERAND(exp, 1)), 0);
  Arg = CastToType(Instruction::BitCast, Arg,
                   PointerType::getUnqual(Type::Int8Ty));
  Builder.CreateCall(Intrinsic::getDeclaration(TheModule, Intrinsic::vaend),
                     Arg);
  return true;
}

bool TreeToLLVM::EmitBuiltinVACopy(tree exp) {
  tree Arg1T = TREE_VALUE(TREE_OPERAND(exp, 1));
  tree Arg2T = TREE_VALUE(TREE_CHAIN(TREE_OPERAND(exp, 1)));
  
  Value *Arg1 = Emit(Arg1T, 0);   // Emit the address of the destination.
  // The second arg of llvm.va_copy is a pointer to a valist.
  Value *Arg2;
  if (!isAggregateTreeType(TREE_TYPE(Arg2T))) {
    // Emit it as a value, then store it to a temporary slot.
    Value *V2 = Emit(Arg2T, 0);
    Arg2 = CreateTemporary(V2->getType());
    Builder.CreateStore(V2, Arg2);
  } else {
    // If the target has aggregate valists, emit the srcval directly into a
    // temporary.
    const Type *VAListTy = cast<PointerType>(Arg1->getType())->getElementType();
    MemRef DestLoc = CreateTempLoc(VAListTy);
    Emit(Arg2T, &DestLoc);
    Arg2 = DestLoc.Ptr;
  }
  
  static const Type *VPTy = PointerType::getUnqual(Type::Int8Ty);

  // FIXME: This ignores alignment and volatility of the arguments.
  SmallVector<Value *, 2> Args;
  Args.push_back(CastToType(Instruction::BitCast, Arg1, VPTy));
  Args.push_back(CastToType(Instruction::BitCast, Arg2, VPTy));

  Builder.CreateCall(Intrinsic::getDeclaration(TheModule, Intrinsic::vacopy),
                     Args.begin(), Args.end());
  return true;
}

bool TreeToLLVM::EmitBuiltinInitTrampoline(tree exp, Value *&Result) {
  tree arglist = TREE_OPERAND(exp, 1);
  if (!validate_arglist (arglist, POINTER_TYPE, POINTER_TYPE, POINTER_TYPE,
                         VOID_TYPE))
    return false;

  static const Type *VPTy = PointerType::getUnqual(Type::Int8Ty);

  Value *Tramp = Emit(TREE_VALUE(arglist), 0);
  Tramp = CastToType(Instruction::BitCast, Tramp, VPTy);

  Value *Func = Emit(TREE_VALUE(TREE_CHAIN(arglist)), 0);
  Func = CastToType(Instruction::BitCast, Func, VPTy);

  Value *Chain = Emit(TREE_VALUE(TREE_CHAIN(TREE_CHAIN(arglist))), 0);
  Chain = CastToType(Instruction::BitCast, Chain, VPTy);

  Value *Ops[3] = { Tramp, Func, Chain };

  Function *Intr = Intrinsic::getDeclaration(TheModule,
                                             Intrinsic::init_trampoline);
  Result = Builder.CreateCall(Intr, Ops, Ops+3, "tramp");
  return true;
}

//===----------------------------------------------------------------------===//
//                      ... Complex Math Expressions ...
//===----------------------------------------------------------------------===//

void TreeToLLVM::EmitLoadFromComplex(Value *&Real, Value *&Imag,
                                     MemRef SrcComplex) {
  Value *I0 = ConstantInt::get(Type::Int32Ty, 0);
  Value *I1 = ConstantInt::get(Type::Int32Ty, 1);
  Value *Idxs[2] = { I0, I0 };
  
  Value *RealPtr = Builder.CreateGEP(SrcComplex.Ptr, Idxs, Idxs + 2, "real");
  Real = Builder.CreateLoad(RealPtr, SrcComplex.Volatile, "real");
  cast<LoadInst>(Real)->setAlignment(SrcComplex.Alignment);

  Idxs[1] = I1;
  Value *ImagPtr = Builder.CreateGEP(SrcComplex.Ptr, Idxs, Idxs + 2, "real");
  Imag = Builder.CreateLoad(ImagPtr, SrcComplex.Volatile, "imag");
  cast<LoadInst>(Imag)->setAlignment(
    MinAlign(SrcComplex.Alignment, TD.getABITypeSize(Real->getType()))
  );
}

void TreeToLLVM::EmitStoreToComplex(MemRef DestComplex, Value *Real,
                                    Value *Imag) {
  Value *I0 = ConstantInt::get(Type::Int32Ty, 0);
  Value *I1 = ConstantInt::get(Type::Int32Ty, 1);  
  Value *Idxs[2] = { I0, I0 };
  StoreInst *St;

  Value *RealPtr = Builder.CreateGEP(DestComplex.Ptr, Idxs, Idxs + 2, "real");
  St = Builder.CreateStore(Real, RealPtr, DestComplex.Volatile);
  St->setAlignment(DestComplex.Alignment);
  
  Idxs[1] = I1;
  Value *ImagPtr = Builder.CreateGEP(DestComplex.Ptr, Idxs, Idxs + 2, "real");
  St = Builder.CreateStore(Imag, ImagPtr, DestComplex.Volatile);
  St->setAlignment(
    MinAlign(DestComplex.Alignment, TD.getABITypeSize(Real->getType()))
  );
}


void TreeToLLVM::EmitCOMPLEX_EXPR(tree exp, const MemRef *DestLoc) {
  Value *Real = Emit(TREE_OPERAND(exp, 0), 0);
  Value *Imag = Emit(TREE_OPERAND(exp, 1), 0);
  EmitStoreToComplex(*DestLoc, Real, Imag);
}

void TreeToLLVM::EmitCOMPLEX_CST(tree exp, const MemRef *DestLoc) {
  Value *Real = Emit(TREE_REALPART(exp), 0);
  Value *Imag = Emit(TREE_IMAGPART(exp), 0);
  EmitStoreToComplex(*DestLoc, Real, Imag);
}

// EmitComplexBinOp - Note that this operands on binops like ==/!=, which return
// a bool, not a complex value.
Value *TreeToLLVM::EmitComplexBinOp(tree exp, const MemRef *DestLoc) {
  const Type *ComplexTy = ConvertType(TREE_TYPE(TREE_OPERAND(exp, 0)));

  MemRef LHSTmp = CreateTempLoc(ComplexTy);
  MemRef RHSTmp = CreateTempLoc(ComplexTy);
  Emit(TREE_OPERAND(exp, 0), &LHSTmp);
  Emit(TREE_OPERAND(exp, 1), &RHSTmp);

  Value *LHSr, *LHSi;
  EmitLoadFromComplex(LHSr, LHSi, LHSTmp);
  Value *RHSr, *RHSi;
  EmitLoadFromComplex(RHSr, RHSi, RHSTmp);
  
  Value *DSTr, *DSTi;
  switch (TREE_CODE(exp)) {
  default: TODO(exp);
  case PLUS_EXPR: // (a+ib) + (c+id) = (a+c) + i(b+d)
    DSTr = Builder.CreateAdd(LHSr, RHSr, "tmpr");
    DSTi = Builder.CreateAdd(LHSi, RHSi, "tmpi");
    break;
  case MINUS_EXPR: // (a+ib) - (c+id) = (a-c) + i(b-d)
    DSTr = Builder.CreateSub(LHSr, RHSr, "tmpr");
    DSTi = Builder.CreateSub(LHSi, RHSi, "tmpi");
    break;
  case MULT_EXPR: { // (a+ib) * (c+id) = (ac-bd) + i(ad+cb)
    Value *Tmp1 = Builder.CreateMul(LHSr, RHSr, "tmp"); // a*c
    Value *Tmp2 = Builder.CreateMul(LHSi, RHSi, "tmp"); // b*d
    DSTr = Builder.CreateSub(Tmp1, Tmp2, "tmp");  // ac-bd

    Value *Tmp3 = Builder.CreateMul(LHSr, RHSi, "tmp"); // a*d
    Value *Tmp4 = Builder.CreateMul(RHSr, LHSi, "tmp"); // c*b
    DSTi = Builder.CreateAdd(Tmp3, Tmp4, "tmp"); // ad+cb
    break;
  }
  case RDIV_EXPR: { // (a+ib) / (c+id) = ((ac+bd)/(cc+dd)) + i((bc-ad)/(cc+dd))
    Value *Tmp1 = Builder.CreateMul(LHSr, RHSr, "tmp"); // a*c
    Value *Tmp2 = Builder.CreateMul(LHSi, RHSi, "tmp"); // b*d
    Value *Tmp3 = Builder.CreateAdd(Tmp1, Tmp2, "tmp"); // ac+bd
    
    Value *Tmp4 = Builder.CreateMul(RHSr, RHSr, "tmp"); // c*c
    Value *Tmp5 = Builder.CreateMul(RHSi, RHSi, "tmp"); // d*d
    Value *Tmp6 = Builder.CreateAdd(Tmp4, Tmp5, "tmp"); // cc+dd
    // FIXME: What about integer complex?
    DSTr = Builder.CreateFDiv(Tmp3, Tmp6, "tmp");

    Value *Tmp7 = Builder.CreateMul(LHSi, RHSr, "tmp"); // b*c
    Value *Tmp8 = Builder.CreateMul(LHSr, RHSi, "tmp"); // a*d
    Value *Tmp9 = Builder.CreateSub(Tmp7, Tmp8, "tmp"); // bc-ad
    DSTi = Builder.CreateFDiv(Tmp9, Tmp6, "tmp");
    break;
  }
  case EQ_EXPR:   // (a+ib) == (c+id) = (a == c) & (b == d)
    if (LHSr->getType()->isFloatingPoint()) {
      DSTr = Builder.CreateFCmpOEQ(LHSr, RHSr, "tmpr");
      DSTi = Builder.CreateFCmpOEQ(LHSi, RHSi, "tmpi");
    } else {
      DSTr = Builder.CreateICmpEQ(LHSr, RHSr, "tmpr");
      DSTi = Builder.CreateICmpEQ(LHSi, RHSi, "tmpi");
    }
    return Builder.CreateAnd(DSTr, DSTi, "tmp");
  case NE_EXPR:   // (a+ib) != (c+id) = (a != c) | (b != d) 
    if (LHSr->getType()->isFloatingPoint()) {
      DSTr = Builder.CreateFCmpUNE(LHSr, RHSr, "tmpr");
      DSTi = Builder.CreateFCmpUNE(LHSi, RHSi, "tmpi");
    } else {
      DSTr = Builder.CreateICmpNE(LHSr, RHSr, "tmpr");
      DSTi = Builder.CreateICmpNE(LHSi, RHSi, "tmpi");
    }
    return Builder.CreateOr(DSTr, DSTi, "tmp");
  }
  
  EmitStoreToComplex(*DestLoc, DSTr, DSTi);
  return 0;
}


//===----------------------------------------------------------------------===//
//                         ... L-Value Expressions ...
//===----------------------------------------------------------------------===//

LValue TreeToLLVM::EmitLV_DECL(tree exp) {
  if (TREE_CODE(exp) == PARM_DECL || TREE_CODE(exp) == VAR_DECL || 
      TREE_CODE(exp) == CONST_DECL) {
    // If a static var's type was incomplete when the decl was written,
    // but the type is complete now, lay out the decl now.
    if (DECL_SIZE(exp) == 0 && COMPLETE_OR_UNBOUND_ARRAY_TYPE_P(TREE_TYPE(exp))
        && (TREE_STATIC(exp) || DECL_EXTERNAL(exp))) {
      layout_decl(exp, 0);
      
      // This mirrors code in layout_decl for munging the RTL.  Here we actually
      // emit a NEW declaration for the global variable, now that it has been
      // laid out.  We then tell the compiler to "forward" any uses of the old
      // global to this new one.
      if (Value *Val = DECL_LLVM_IF_SET(exp)) {
        //fprintf(stderr, "***\n*** SHOULD HANDLE GLOBAL VARIABLES!\n***\n");
        //assert(0 && "Reimplement this with replace all uses!");
#if 0
        SET_DECL_LLVM(exp, 0);
        // Create a new global variable declaration
        llvm_assemble_external(exp);
        V2GV(Val)->ForwardedGlobal = V2GV(DECL_LLVM(exp));
#endif
      }
    }
  }

  assert(!isGCC_SSA_Temporary(exp) &&
         "Cannot use an SSA temporary as an l-value");
  
  Value *Decl = DECL_LLVM(exp);
  if (Decl == 0) {
    if (errorcount || sorrycount) {
      const PointerType *Ty = 
        PointerType::getUnqual(ConvertType(TREE_TYPE(exp)));
      return ConstantPointerNull::get(Ty);
    }
    assert(0 && "INTERNAL ERROR: Referencing decl that hasn't been laid out");
    abort();
  }
  
  // Ensure variable marked as used even if it doesn't go through a parser.  If
  // it hasn't been used yet, write out an external definition.
  if (!TREE_USED(exp)) {
    assemble_external(exp);
    TREE_USED(exp) = 1;
    Decl = DECL_LLVM(exp);
  }
  
  if (GlobalValue *GV = dyn_cast<GlobalValue>(Decl)) {
    // If this is an aggregate CONST_DECL, emit it to LLVM now.  GCC happens to
    // get this case right by forcing the initializer into memory.
    if (TREE_CODE(exp) == CONST_DECL) {
      if (DECL_INITIAL(exp) && GV->isDeclaration()) {
        emit_global_to_llvm(exp);
        Decl = DECL_LLVM(exp);     // Decl could have change if it changed type.
      }
    } else {
      // Otherwise, inform cgraph that we used the global.
      mark_decl_referenced(exp);
      if (tree ID = DECL_ASSEMBLER_NAME(exp))
        mark_referenced(ID);
    }
  }
  
  const Type *Ty = ConvertType(TREE_TYPE(exp));
  // If we have "extern void foo", make the global have type {} instead of
  // type void.
  if (Ty == Type::VoidTy) Ty = StructType::get(std::vector<const Type*>(),
                                               false);
  const PointerType *PTy = PointerType::getUnqual(Ty);
  return CastToType(Instruction::BitCast, Decl, PTy);
}

LValue TreeToLLVM::EmitLV_ARRAY_REF(tree exp) {
  // The result type is an ElementTy* in the case of an ARRAY_REF, an array
  // of ElementTy in the case of ARRAY_RANGE_REF.

  tree Array = TREE_OPERAND(exp, 0);
  tree ArrayType = TREE_TYPE(Array);
  tree Index = TREE_OPERAND(exp, 1);
  tree IndexType = TREE_TYPE(Index);
  tree ElementType = TREE_TYPE(ArrayType);

  assert((TREE_CODE (ArrayType) == ARRAY_TYPE ||
          TREE_CODE (ArrayType) == POINTER_TYPE ||
          TREE_CODE (ArrayType) == REFERENCE_TYPE) &&
         "Unknown ARRAY_REF!");

  // As an LLVM extension, we allow ARRAY_REF with a pointer as the first
  // operand.  This construct maps directly to a getelementptr instruction.
  Value *ArrayAddr;

  if (TREE_CODE(ArrayType) == ARRAY_TYPE) {
    // First subtract the lower bound, if any, in the type of the index.
    tree LowerBound = array_ref_low_bound(exp);
    if (!integer_zerop(LowerBound))
      Index = fold(build2(MINUS_EXPR, IndexType, Index, LowerBound));

    LValue ArrayAddrLV = EmitLV(Array);
    assert(!ArrayAddrLV.isBitfield() && "Arrays cannot be bitfields!");
    ArrayAddr = ArrayAddrLV.Ptr;
  } else {
    ArrayAddr = Emit(Array, 0);
  }

  Value *IndexVal = Emit(Index, 0);

  const Type *IntPtrTy = getTargetData().getIntPtrType();
  if (TYPE_UNSIGNED(IndexType)) // if the index is unsigned
    // ZExt it to retain its value in the larger type
    IndexVal = CastToUIntType(IndexVal, IntPtrTy);
  else
    // SExt it to retain its value in the larger type
    IndexVal = CastToSIntType(IndexVal, IntPtrTy);

  // If this is an index into an LLVM array, codegen as a GEP.
  if (isArrayCompatible(ArrayType)) {
    Value *Idxs[2] = { ConstantInt::get(Type::Int32Ty, 0), IndexVal };
    Value *Ptr = Builder.CreateGEP(ArrayAddr, Idxs, Idxs + 2, "tmp");
    return BitCastToType(Ptr, 
                         PointerType::getUnqual(ConvertType(TREE_TYPE(exp))));
  }

  // If we are indexing over a fixed-size type, just use a GEP.
  if (isSequentialCompatible(ArrayType)) {
    const Type *PtrElementTy = PointerType::getUnqual(ConvertType(ElementType));
    ArrayAddr = BitCastToType(ArrayAddr, PtrElementTy);
    Value *Ptr = Builder.CreateGEP(ArrayAddr, IndexVal, "tmp");
    return BitCastToType(Ptr, 
                         PointerType::getUnqual(ConvertType(TREE_TYPE(exp))));
  }

  // Otherwise, just do raw, low-level pointer arithmetic.  FIXME: this could be
  // much nicer in cases like:
  //   float foo(int w, float A[][w], int g) { return A[g][0]; }

  ArrayAddr = BitCastToType(ArrayAddr, PointerType::getUnqual(Type::Int8Ty));

  if (VOID_TYPE_P(TREE_TYPE(ArrayType)))
    // void * size is 1
    return Builder.CreateGEP(ArrayAddr, IndexVal, "tmp");
  
  Value *TypeSize = Emit(array_ref_element_size(exp), 0);
  TypeSize = CastToUIntType(TypeSize, IntPtrTy);
  IndexVal = Builder.CreateMul(IndexVal, TypeSize, "tmp");
  Value *Ptr = Builder.CreateGEP(ArrayAddr, IndexVal, "tmp");
  return BitCastToType(Ptr, 
                       PointerType::getUnqual(ConvertType(TREE_TYPE(exp))));
}

/// getFieldOffsetInBits - Return the offset (in bits) of a FIELD_DECL in a
/// structure.
static unsigned getFieldOffsetInBits(tree Field) {
  assert(DECL_FIELD_BIT_OFFSET(Field) != 0 && DECL_FIELD_OFFSET(Field) != 0);
  unsigned Result = TREE_INT_CST_LOW(DECL_FIELD_BIT_OFFSET(Field));
  if (TREE_CODE(DECL_FIELD_OFFSET(Field)) == INTEGER_CST)
    Result += TREE_INT_CST_LOW(DECL_FIELD_OFFSET(Field))*8;
  return Result;
}

/// getComponentRefOffsetInBits - Return the offset (in bits) of the field
/// referenced in a COMPONENT_REF exp.
static unsigned getComponentRefOffsetInBits(tree exp) {
  assert(TREE_CODE(exp) == COMPONENT_REF && "not a COMPONENT_REF!");
  tree field = TREE_OPERAND(exp, 1);
  assert(TREE_CODE(field) == FIELD_DECL && "not a FIELD_DECL!");
  tree field_offset = component_ref_field_offset (exp);
  assert(DECL_FIELD_BIT_OFFSET(field) && field_offset);
  unsigned Result = TREE_INT_CST_LOW(DECL_FIELD_BIT_OFFSET(field));
  if (TREE_CODE(field_offset) == INTEGER_CST)
    Result += TREE_INT_CST_LOW(field_offset)*8;
  return Result;
}

LValue TreeToLLVM::EmitLV_COMPONENT_REF(tree exp) {
  LValue StructAddrLV = EmitLV(TREE_OPERAND(exp, 0));
  tree FieldDecl = TREE_OPERAND(exp, 1);

  assert((TREE_CODE(DECL_CONTEXT(FieldDecl)) == RECORD_TYPE ||
          TREE_CODE(DECL_CONTEXT(FieldDecl)) == UNION_TYPE));
   
  // Ensure that the struct type has been converted, so that the fielddecls
  // are laid out.  Note that we convert to the context of the Field, not to the
  // type of Operand #0, because GCC doesn't always have the field match up with
  // operand #0's type.
  const Type *StructTy = ConvertType(DECL_CONTEXT(FieldDecl));
  
  assert((!StructAddrLV.isBitfield() || 
          StructAddrLV.BitStart == 0) && "structs cannot be bitfields!");

  StructAddrLV.Ptr = CastToType(Instruction::BitCast, StructAddrLV.Ptr, 
                                PointerType::getUnqual(StructTy));
  const Type *FieldTy = ConvertType(TREE_TYPE(FieldDecl));
  
  // BitStart - This is the actual offset of the field from the start of the
  // struct, in bits.  For bitfields this may be on a non-byte boundary.
  unsigned BitStart = getComponentRefOffsetInBits(exp);
  Value *FieldPtr;
  
  tree field_offset = component_ref_field_offset (exp);
  // If this is a normal field at a fixed offset from the start, handle it.
  if (TREE_CODE(field_offset) == INTEGER_CST) {
    assert(DECL_LLVM_SET_P(FieldDecl) && "Struct not laid out for LLVM?");
    ConstantInt *CI = cast<ConstantInt>(DECL_LLVM(FieldDecl));
    uint32_t MemberIndex = CI->getZExtValue();
    assert(MemberIndex < StructTy->getNumContainedTypes() &&
           "Field Idx out of range!");
    Value *Idxs[2] = { Constant::getNullValue(Type::Int32Ty), CI };
    FieldPtr = Builder.CreateGEP(StructAddrLV.Ptr, Idxs, Idxs + 2, "tmp");
    
    // Now that we did an offset from the start of the struct, subtract off
    // the offset from BitStart.
    if (MemberIndex) {
      const StructLayout *SL = TD.getStructLayout(cast<StructType>(StructTy));
      BitStart -= SL->getElementOffset(MemberIndex) * 8;
    }
    
  } else {
    Value *Offset = Emit(field_offset, 0);

    // Here BitStart gives the offset of the field in bits from field_offset.
    // Incorporate as much of it as possible into the pointer computation.
    unsigned ByteOffset = BitStart/8;
    if (ByteOffset > 0) {
      Offset = Builder.CreateAdd(Offset,
        ConstantInt::get(Offset->getType(), ByteOffset), "tmp");
      BitStart -= ByteOffset*8;
    }

    Value *Ptr = CastToType(Instruction::PtrToInt, StructAddrLV.Ptr, 
                            Offset->getType());
    Ptr = Builder.CreateAdd(Ptr, Offset, "tmp");
    FieldPtr = CastToType(Instruction::IntToPtr, Ptr, 
                          PointerType::getUnqual(FieldTy));
  }

  if (tree DeclaredType = DECL_BIT_FIELD_TYPE(FieldDecl)) {
    assert(DECL_SIZE(FieldDecl) &&
           TREE_CODE(DECL_SIZE(FieldDecl)) == INTEGER_CST &&
           "Variable sized bitfield?");
    unsigned BitfieldSize = TREE_INT_CST_LOW(DECL_SIZE(FieldDecl));

    const Type *LLVMFieldTy =
      cast<PointerType>(FieldPtr->getType())->getElementType();

    // If this is a bitfield, the declared type must be an integral type.
    FieldTy = ConvertType(DeclaredType);
    // If the field result is a bool, cast to a ubyte instead.  It is not
    // possible to access all bits of a memory object with a bool (only the low
    // bit) but it is possible to access them with a byte.
    if (FieldTy == Type::Int1Ty)
      FieldTy = Type::Int8Ty;
    assert(FieldTy->isInteger() && "Invalid bitfield");

    // If the LLVM notion of the field type contains the entire bitfield being
    // accessed, use the LLVM type.  This avoids pointer casts and other bad
    // things that are difficult to clean up later.  This occurs in cases like
    // "struct X{ unsigned long long x:50; unsigned y:2; }" when accessing y.
    // We want to access the field as a ulong, not as a uint with an offset.
    if (LLVMFieldTy->isInteger() &&
        LLVMFieldTy->getPrimitiveSizeInBits() >= BitStart + BitfieldSize)
      FieldTy = LLVMFieldTy;

    // We are now loading/storing through a casted pointer type, whose
    // signedness depends on the signedness of the field.  Force the field to
    // be unsigned.  This solves performance problems where you have, for
    // example:  struct { int A:1; unsigned B:2; };  Consider a store to A then
    // a store to B.  In this case, without this conversion, you'd have a
    // store through an int*, followed by a load from a uint*.  Forcing them
    // both to uint* allows the store to be forwarded to the load.

    // If this is a bitfield, the field may span multiple fields in the LLVM
    // type.  As such, cast the pointer to be a pointer to the declared type.
    FieldPtr = BitCastToType(FieldPtr, PointerType::getUnqual(FieldTy));

    unsigned LLVMValueBitSize = FieldTy->getPrimitiveSizeInBits();
    // Finally, because bitfields can span LLVM fields, and because the start
    // of the first LLVM field (where FieldPtr currently points) may be up to
    // 63 bits away from the start of the bitfield), it is possible that
    // *FieldPtr doesn't contain any of the bits for this bitfield. If needed,
    // adjust FieldPtr so that it is close enough to the bitfield that
    // *FieldPtr contains the first needed bit.  Be careful to make sure that
    // the pointer remains appropriately aligned.
    if (BitStart > LLVMValueBitSize) {
      // In this case, we know that the alignment of the field is less than
      // the size of the field.  To get the pointer close enough, add some
      // number of alignment units to the pointer.
      unsigned ByteAlignment = TD.getABITypeAlignment(FieldTy);
      // It is possible that an individual field is Packed. This information is
      // not reflected in FieldTy. Check DECL_PACKED here.
      if (DECL_PACKED(FieldDecl))
        ByteAlignment = 1;
      assert(ByteAlignment*8 <= LLVMValueBitSize && "Unknown overlap case!");
      unsigned NumAlignmentUnits = BitStart/(ByteAlignment*8);
      assert(NumAlignmentUnits && "Not adjusting pointer?");

      // Compute the byte offset, and add it to the pointer.
      unsigned ByteOffset = NumAlignmentUnits*ByteAlignment;

      Constant *Offset = ConstantInt::get(TD.getIntPtrType(), ByteOffset);
      FieldPtr = CastToType(Instruction::PtrToInt, FieldPtr,
                            Offset->getType());
      FieldPtr = Builder.CreateAdd(FieldPtr, Offset, "tmp");
      FieldPtr = CastToType(Instruction::IntToPtr, FieldPtr,
                            PointerType::getUnqual(FieldTy));

      // Adjust bitstart to account for the pointer movement.
      BitStart -= ByteOffset*8;

      // Check that this worked.  Note that the bitfield may extend beyond
      // the end of *FieldPtr, for example because BitfieldSize is the same
      // as LLVMValueBitSize but BitStart > 0.
      assert(BitStart < LLVMValueBitSize &&
             BitStart+BitfieldSize < 2*LLVMValueBitSize &&
             "Couldn't get bitfield into value!");
    }

    // Okay, everything is good.  Return this as a bitfield if we can't
    // return it as a normal l-value. (e.g. "struct X { int X : 32 };" ).
    if (BitfieldSize != LLVMValueBitSize || BitStart != 0)
      return LValue(FieldPtr, BitStart, BitfieldSize);
  } else {
    // Make sure we return a pointer to the right type.
    FieldPtr = CastToType(Instruction::BitCast, FieldPtr,
                          PointerType::getUnqual(ConvertType(TREE_TYPE(exp))));
  }
  
  assert(BitStart == 0 &&
         "It's a bitfield reference or we didn't get to the field!");
  return LValue(FieldPtr);
}

LValue TreeToLLVM::EmitLV_BIT_FIELD_REF(tree exp) {
  LValue Ptr = EmitLV(TREE_OPERAND(exp, 0));
  assert(!Ptr.isBitfield() && "BIT_FIELD_REF operands cannot be bitfields!");
  
  unsigned BitStart = (unsigned)TREE_INT_CST_LOW(TREE_OPERAND(exp, 2));
  unsigned BitSize = (unsigned)TREE_INT_CST_LOW(TREE_OPERAND(exp, 1));
  const Type *ValTy = ConvertType(TREE_TYPE(exp));
  
  unsigned ValueSizeInBits = TD.getTypeSizeInBits(ValTy);
  assert(BitSize <= ValueSizeInBits &&
         "ValTy isn't large enough to hold the value loaded!");

  // BIT_FIELD_REF values can have BitStart values that are quite large.  We
  // know that the thing we are loading is ValueSizeInBits large.  If BitStart
  // is larger than ValueSizeInBits, bump the pointer over to where it should
  // be.
  if (unsigned UnitOffset = BitStart / ValueSizeInBits) {
    // TODO: If Ptr.Ptr is a struct type or something, we can do much better
    // than this.  e.g. check out when compiling unwind-dw2-fde-darwin.c.
    Ptr.Ptr = CastToType(Instruction::BitCast, Ptr.Ptr, 
                         PointerType::getUnqual(ValTy));
    Ptr.Ptr = Builder.CreateGEP(Ptr.Ptr,
                                ConstantInt::get(Type::Int32Ty, UnitOffset),
                                "tmp");
    BitStart -= UnitOffset*ValueSizeInBits;
  }
  
  // If this is referring to the whole field, return the whole thing.
  if (BitStart == 0 && BitSize == ValueSizeInBits)
    return LValue(BitCastToType(Ptr.Ptr, PointerType::getUnqual(ValTy)));
  
  return LValue(BitCastToType(Ptr.Ptr, PointerType::getUnqual(ValTy)), BitStart, 
                BitSize);
}

LValue TreeToLLVM::EmitLV_XXXXPART_EXPR(tree exp, unsigned Idx) {
  LValue Ptr = EmitLV(TREE_OPERAND(exp, 0));
  assert(!Ptr.isBitfield() && "BIT_FIELD_REF operands cannot be bitfields!");

  Value *Idxs[2] = { ConstantInt::get(Type::Int32Ty, 0),
                     ConstantInt::get(Type::Int32Ty, Idx) };
  return LValue(Builder.CreateGEP(Ptr.Ptr, Idxs, Idxs + 2, "tmp"));
}

LValue TreeToLLVM::EmitLV_VIEW_CONVERT_EXPR(tree exp) {
  tree Op = TREE_OPERAND(exp, 0);

  if (isAggregateTreeType(TREE_TYPE(Op))) {
    // If the input is an aggregate, the address is the address of the operand.
    LValue LV = EmitLV(Op);
    // The type is the type of the expression.
    LV.Ptr = BitCastToType(LV.Ptr, 
                           PointerType::getUnqual(ConvertType(TREE_TYPE(exp))));
    return LV;
  } else {
    // If the input is a scalar, emit to a temporary.
    Value *Dest = CreateTemporary(ConvertType(TREE_TYPE(Op)));
    Builder.CreateStore(Emit(Op, 0), Dest);
    // The type is the type of the expression.
    Dest = BitCastToType(Dest, 
                         PointerType::getUnqual(ConvertType(TREE_TYPE(exp))));
    return LValue(Dest);
  }
}

//===----------------------------------------------------------------------===//
//                       ... Constant Expressions ...
//===----------------------------------------------------------------------===//

/// EmitCONSTRUCTOR - emit the constructor into the location specified by
/// DestLoc.
Value *TreeToLLVM::EmitCONSTRUCTOR(tree exp, const MemRef *DestLoc) {
  tree type = TREE_TYPE(exp);
  const Type *Ty = ConvertType(type);
  if (const VectorType *PTy = dyn_cast<VectorType>(Ty)) {
    assert(DestLoc == 0 && "Dest location for packed value?");
    
    std::vector<Value *> BuildVecOps;
    
    // Insert zero initializers for any uninitialized values.
    Constant *Zero = Constant::getNullValue(PTy->getElementType());
    BuildVecOps.resize(cast<VectorType>(Ty)->getNumElements(), Zero);
    
    // Insert all of the elements here.
    for (tree Ops = TREE_OPERAND(exp, 0); Ops; Ops = TREE_CHAIN(Ops)) {
      if (!TREE_PURPOSE(Ops)) continue;  // Not actually initialized?
      
      unsigned FieldNo = TREE_INT_CST_LOW(TREE_PURPOSE(Ops));

      // Update the element.
      if (FieldNo < BuildVecOps.size())
        BuildVecOps[FieldNo] = Emit(TREE_VALUE(Ops), 0);
    }
    
    return BuildVector(BuildVecOps);
  }

  assert(!Ty->isFirstClassType() && "Constructor for scalar type??");
  
  // Start out with the value zero'd out.
  EmitAggregateZero(*DestLoc, type);
  
  tree elt = CONSTRUCTOR_ELTS(exp);
  switch (TREE_CODE(TREE_TYPE(exp))) {
  case ARRAY_TYPE:
  case RECORD_TYPE:
  default:
    if (elt) {
      // We don't handle elements yet.
      TODO(exp);
    }
    return 0;
  case UNION_TYPE:
    // Store each element of the constructor into the corresponding field of
    // DEST.
    if (elt == NULL_TREE) return 0;  // no elements
    assert(TREE_CHAIN(elt) == 0 &&"Union CONSTRUCTOR should have one element!");
    if (!TREE_PURPOSE(elt)) return 0;  // Not actually initialized?
      
    if (!ConvertType(TREE_TYPE(TREE_PURPOSE(elt)))->isFirstClassType()) {
      Value *V = Emit(TREE_VALUE(elt), DestLoc);
      assert(V == 0 && "Aggregate value returned in a register?");
    } else {
      // Scalar value.  Evaluate to a register, then do the store.
      Value *V = Emit(TREE_VALUE(elt), 0);
      Value *Ptr = CastToType(Instruction::BitCast, DestLoc->Ptr,
                              PointerType::getUnqual(V->getType()));
      StoreInst *St = Builder.CreateStore(V, Ptr, DestLoc->Volatile);
      St->setAlignment(DestLoc->Alignment);
    }
    break;
  }
  return 0;
}

Constant *TreeConstantToLLVM::Convert(tree exp) {
  // Some front-ends use constants other than the standard language-independent
  // varieties, but which may still be output directly.  Give the front-end a
  // chance to convert EXP to a language-independent representation.
  exp = lang_hooks.expand_constant (exp);

  assert((TREE_CONSTANT(exp) || TREE_CODE(exp) == STRING_CST) &&
         "Isn't a constant!");
  switch (TREE_CODE(exp)) {
  case FDESC_EXPR:    // Needed on itanium
  default: 
    debug_tree(exp); 
    assert(0 && "Unknown constant to convert!");
    abort();
  case INTEGER_CST:   return ConvertINTEGER_CST(exp);
  case REAL_CST:      return ConvertREAL_CST(exp);
  case VECTOR_CST:    return ConvertVECTOR_CST(exp);
  case STRING_CST:    return ConvertSTRING_CST(exp);
  case COMPLEX_CST:   return ConvertCOMPLEX_CST(exp);
  case NOP_EXPR:      return ConvertNOP_EXPR(exp);
  case CONVERT_EXPR:  return ConvertCONVERT_EXPR(exp);
  case PLUS_EXPR:
  case MINUS_EXPR:    return ConvertBinOp_CST(exp);
  case CONSTRUCTOR:   return ConvertCONSTRUCTOR(exp);
  case VIEW_CONVERT_EXPR: return Convert(TREE_OPERAND(exp, 0));
  case ADDR_EXPR:     
    return ConstantExpr::getBitCast(EmitLV(TREE_OPERAND(exp, 0)),
                                 ConvertType(TREE_TYPE(exp)));
  }
}

Constant *TreeConstantToLLVM::ConvertINTEGER_CST(tree exp) {
  // Convert it to a uint64_t.
  uint64_t IntValue = getINTEGER_CSTVal(exp);
  
  // Build the value as a ulong constant, then constant fold it to the right
  // type.  This handles overflow and other things appropriately.
  const Type *Ty = ConvertType(TREE_TYPE(exp));
  ConstantInt *C = ConstantInt::get(Type::Int64Ty, IntValue);
  // The destination type can be a pointer, integer or floating point 
  // so we need a generalized cast here
  Instruction::CastOps opcode = CastInst::getCastOpcode(C, false, Ty,
      !TYPE_UNSIGNED(TREE_TYPE(exp)));
  return ConstantExpr::getCast(opcode, C, Ty);
}

Constant *TreeConstantToLLVM::ConvertREAL_CST(tree exp) {
  const Type *Ty = ConvertType(TREE_TYPE(exp));
  assert(Ty->isFloatingPoint() && "Integer REAL_CST?");
  long RealArr[2];
  union {
    int UArr[2];
    double V;
  };
  if (Ty==Type::FloatTy || Ty==Type::DoubleTy) {
    REAL_VALUE_TO_TARGET_DOUBLE(TREE_REAL_CST(exp), RealArr);

    // Here's how this works:
    // REAL_VALUE_TO_TARGET_DOUBLE() will generate the floating point number
    //  as an array of integers in the hosts's representation.  Each integer
    // in the array will hold 32 bits of the result REGARDLESS OF THE HOST'S
    //  INTEGER SIZE.
    //
    // This, then, makes the conversion pretty simple.  The tricky part is
    // getting the byte ordering correct and make sure you don't print any
    // more than 32 bits per integer on platforms with ints > 32 bits.
    //
    bool HostBigEndian = false;
#ifdef HOST_WORDS_BIG_ENDIAN
    HostBigEndian = true;
#endif

    UArr[0] = RealArr[0];   // Long -> int convert
    UArr[1] = RealArr[1];

    if (WORDS_BIG_ENDIAN != HostBigEndian)
      std::swap(UArr[0], UArr[1]);

    return ConstantFP::get(Ty, Ty==Type::FloatTy ? APFloat((float)V)
                                                 : APFloat(V));
  } else if (Ty==Type::X86_FP80Ty) {
    long RealArr[4];
    uint64_t UArr[2];
    REAL_VALUE_TO_TARGET_LONG_DOUBLE(TREE_REAL_CST(exp), RealArr);

    UArr[0] = ((uint64_t)((uint16_t)RealArr[2]) << 48) |
              ((uint64_t)((uint32_t)RealArr[1]) << 16) |
              ((uint64_t)((uint16_t)(RealArr[0] >> 16)));
    UArr[1] = (uint16_t)RealArr[0];

    return ConstantFP::get(Ty, APFloat(APInt(80, 2, UArr)));
  } else if (Ty==Type::PPC_FP128Ty) {
    long RealArr[4];
    uint64_t UArr[2];
    REAL_VALUE_TO_TARGET_LONG_DOUBLE(TREE_REAL_CST(exp), RealArr);

    UArr[0] = ((uint64_t)((uint32_t)RealArr[0]) << 32) |
              ((uint64_t)((uint32_t)RealArr[1]));
    UArr[1] = ((uint64_t)((uint32_t)RealArr[2]) << 32) |
              ((uint64_t)((uint32_t)RealArr[3]));
    return ConstantFP::get(Ty, APFloat(APInt(128, 2, UArr)));
  }
  assert(0 && "Floating point type not handled yet");
  return 0;   // outwit compiler warning
}

Constant *TreeConstantToLLVM::ConvertVECTOR_CST(tree exp) {
  if (TREE_VECTOR_CST_ELTS(exp)) {
    std::vector<Constant*> Elts;
    for (tree elt = TREE_VECTOR_CST_ELTS(exp); elt; elt = TREE_CHAIN(elt))
      Elts.push_back(Convert(TREE_VALUE(elt)));
    
    // The vector should be zero filled if insufficient elements are provided.
    if (Elts.size() < TYPE_VECTOR_SUBPARTS(TREE_TYPE(exp))) {
      tree EltType = TREE_TYPE(TREE_TYPE(exp));
      Constant *Zero = Constant::getNullValue(ConvertType(EltType));
      while (Elts.size() < TYPE_VECTOR_SUBPARTS(TREE_TYPE(exp)))
        Elts.push_back(Zero);
    }
    
    return ConstantVector::get(Elts);
  } else {
    return Constant::getNullValue(ConvertType(TREE_TYPE(exp)));
  }
}

Constant *TreeConstantToLLVM::ConvertSTRING_CST(tree exp) {
  const ArrayType *StrTy = cast<ArrayType>(ConvertType(TREE_TYPE(exp)));
  const Type *ElTy = StrTy->getElementType();
  
  unsigned Len = (unsigned)TREE_STRING_LENGTH(exp);
  
  std::vector<Constant*> Elts;
  if (ElTy == Type::Int8Ty) {
    const unsigned char *InStr =(const unsigned char *)TREE_STRING_POINTER(exp);
    for (unsigned i = 0; i != Len; ++i)
      Elts.push_back(ConstantInt::get(Type::Int8Ty, InStr[i]));
  } else if (ElTy == Type::Int16Ty) {
    const unsigned short *InStr =
      (const unsigned short *)TREE_STRING_POINTER(exp);
    for (unsigned i = 0; i != Len; ++i)
      Elts.push_back(ConstantInt::get(Type::Int16Ty, InStr[i]));
  } else if (ElTy == Type::Int32Ty) {
    const unsigned *InStr = (const unsigned *)TREE_STRING_POINTER(exp);
    for (unsigned i = 0; i != Len; ++i)
      Elts.push_back(ConstantInt::get(Type::Int32Ty, InStr[i]));
  } else {
    assert(0 && "Unknown character type!");
  }
  
  unsigned ConstantSize = StrTy->getNumElements();
  
  if (Len != ConstantSize) {
    // If this is a variable sized array type, set the length to Len.
    if (ConstantSize == 0) {
      tree Domain = TYPE_DOMAIN(TREE_TYPE(exp));
      if (!Domain || !TYPE_MAX_VALUE(Domain)) {
        ConstantSize = Len;
        StrTy = ArrayType::get(ElTy, Len);
      }
    }
    
    if (ConstantSize < Len) {
      // Only some chars are being used, truncate the string: char X[2] = "foo";
      Elts.resize(ConstantSize);
    } else {
      // Fill the end of the string with nulls.
      Constant *C = Constant::getNullValue(ElTy);
      for (; Len != ConstantSize; ++Len)
        Elts.push_back(C);
    }
  }
  return ConstantArray::get(StrTy, Elts);
}

Constant *TreeConstantToLLVM::ConvertCOMPLEX_CST(tree exp) {
  std::vector<Constant*> Elts;
  Elts.push_back(Convert(TREE_REALPART(exp)));
  Elts.push_back(Convert(TREE_IMAGPART(exp)));
  return ConstantStruct::get(Elts, false);
}

Constant *TreeConstantToLLVM::ConvertNOP_EXPR(tree exp) {
  Constant *Elt = Convert(TREE_OPERAND(exp, 0));
  const Type *Ty = ConvertType(TREE_TYPE(exp));
  bool EltIsSigned = !TYPE_UNSIGNED(TREE_TYPE(TREE_OPERAND(exp, 0)));
  bool TyIsSigned = !TYPE_UNSIGNED(TREE_TYPE(exp));
  
  // If this is a structure-to-structure cast, just return the uncasted value.
  if (!Elt->getType()->isFirstClassType() || !Ty->isFirstClassType())
    return Elt;
  
  // Elt and Ty can be integer, float or pointer here: need generalized cast
  Instruction::CastOps opcode = CastInst::getCastOpcode(Elt, EltIsSigned,
                                                        Ty, TyIsSigned);
  return ConstantExpr::getCast(opcode, Elt, Ty);
}

Constant *TreeConstantToLLVM::ConvertCONVERT_EXPR(tree exp) {
  Constant *Elt = Convert(TREE_OPERAND(exp, 0));
  bool EltIsSigned = !TYPE_UNSIGNED(TREE_TYPE(TREE_OPERAND(exp, 0)));
  const Type *Ty = ConvertType(TREE_TYPE(exp));
  bool TyIsSigned = !TYPE_UNSIGNED(TREE_TYPE(exp));
  Instruction::CastOps opcode = CastInst::getCastOpcode(Elt, EltIsSigned, Ty, 
                                                        TyIsSigned); 
  return ConstantExpr::getCast(opcode, Elt, Ty);
}

Constant *TreeConstantToLLVM::ConvertBinOp_CST(tree exp) {
  Constant *LHS = Convert(TREE_OPERAND(exp, 0));
  bool LHSIsSigned = !TYPE_UNSIGNED(TREE_TYPE(TREE_OPERAND(exp,0)));
  Constant *RHS = Convert(TREE_OPERAND(exp, 1));
  bool RHSIsSigned = !TYPE_UNSIGNED(TREE_TYPE(TREE_OPERAND(exp,1)));
  Instruction::CastOps opcode;
  if (isa<PointerType>(LHS->getType())) {
    const Type *IntPtrTy = getTargetData().getIntPtrType();
    opcode = CastInst::getCastOpcode(LHS, LHSIsSigned, IntPtrTy, false);
    LHS = ConstantExpr::getCast(opcode, LHS, IntPtrTy);
    opcode = CastInst::getCastOpcode(RHS, RHSIsSigned, IntPtrTy, false);
    RHS = ConstantExpr::getCast(opcode, RHS, IntPtrTy);
  }

  Constant *Result;
  switch (TREE_CODE(exp)) {
  default: assert(0 && "Unexpected case!");
  case PLUS_EXPR:   Result = ConstantExpr::getAdd(LHS, RHS); break;
  case MINUS_EXPR:  Result = ConstantExpr::getSub(LHS, RHS); break;
  }
  
  const Type *Ty = ConvertType(TREE_TYPE(exp));
  bool TyIsSigned = !TYPE_UNSIGNED(TREE_TYPE(exp));
  opcode = CastInst::getCastOpcode(Result, LHSIsSigned, Ty, TyIsSigned);
  return ConstantExpr::getCast(opcode, Result, Ty);
}

Constant *TreeConstantToLLVM::ConvertCONSTRUCTOR(tree exp) {
  if (CONSTRUCTOR_ELTS(exp) == 0)  // All zeros?
    return Constant::getNullValue(ConvertType(TREE_TYPE(exp)));

  switch (TREE_CODE(TREE_TYPE(exp))) {
  default: 
    debug_tree(exp);
    assert(0 && "Unknown ctor!");
  case VECTOR_TYPE:
  case ARRAY_TYPE:  return ConvertArrayCONSTRUCTOR(exp);
  case RECORD_TYPE: return ConvertRecordCONSTRUCTOR(exp);
  case UNION_TYPE:  return ConvertUnionCONSTRUCTOR(exp);
  }
}

Constant *TreeConstantToLLVM::ConvertArrayCONSTRUCTOR(tree exp) {
  // Vectors are like arrays, but the domain is stored via an array
  // type indirectly.

  // If we have a lower bound for the range of the type, get it.
  tree InitType = TREE_TYPE(exp);
  tree min_element = size_zero_node;
  std::vector<Constant*> ResultElts;
  
  if (TREE_CODE(InitType) == VECTOR_TYPE) {
    ResultElts.resize(TYPE_VECTOR_SUBPARTS(InitType));
  } else {
    assert(TREE_CODE(InitType) == ARRAY_TYPE && "Unknown type for init");
    tree Domain = TYPE_DOMAIN(InitType);
    if (Domain && TYPE_MIN_VALUE(Domain))
      min_element = fold_convert(sizetype, TYPE_MIN_VALUE(Domain));
    
    if (Domain && TYPE_MAX_VALUE(Domain)) {
      tree max_element = fold_convert(sizetype, TYPE_MAX_VALUE(Domain));
      tree size = size_binop (MINUS_EXPR, max_element, min_element);
      size = size_binop (PLUS_EXPR, size, size_one_node);
      
      if (host_integerp(size, 1))
        ResultElts.resize(tree_low_cst(size, 1));
    }
  }
  
  unsigned NextFieldToFill = 0;
  Constant *SomeVal = 0;
  for (tree elt = CONSTRUCTOR_ELTS(exp); elt; elt = TREE_CHAIN(elt)) {
    // Find and decode the constructor's value.
    Constant *Val = Convert(TREE_VALUE(elt));
    SomeVal = Val;
    
    // Get the index position of the element within the array.  Note that this
    // can be NULL_TREE, which means that it belongs in the next available slot.
    tree index = TREE_PURPOSE(elt);
    
    // The first and last field to fill in, inclusive.
    unsigned FieldOffset, FieldLastOffset;
    if (index && TREE_CODE(index) == RANGE_EXPR) {
      tree first = fold_convert (sizetype, TREE_OPERAND(index, 0));
      tree last  = fold_convert (sizetype, TREE_OPERAND(index, 1));

      first = size_binop (MINUS_EXPR, first, min_element);
      last  = size_binop (MINUS_EXPR, last, min_element);

      assert(host_integerp(first, 1) && host_integerp(last, 1) &&
             "Unknown range_expr!");
      FieldOffset     = tree_low_cst(first, 1);
      FieldLastOffset = tree_low_cst(last, 1);
    } else if (index) {
      index = size_binop (MINUS_EXPR, fold_convert (sizetype, index),
                          min_element);
      assert(host_integerp(index, 1));
      FieldOffset = tree_low_cst(index, 1);
      FieldLastOffset = FieldOffset;
    } else {
      FieldOffset = NextFieldToFill;
      FieldLastOffset = FieldOffset;
    }
    
    // Process all of the elements in the range.
    for (--FieldOffset; FieldOffset != FieldLastOffset; ) {
      ++FieldOffset;
      if (FieldOffset == ResultElts.size())
        ResultElts.push_back(Val);
      else {
        if (FieldOffset >= ResultElts.size())
          ResultElts.resize(FieldOffset+1);
        ResultElts[FieldOffset] = Val;
      }
      
      NextFieldToFill = FieldOffset+1;
    }
  }
  
  // Zero length array.
  if (ResultElts.empty())
    return ConstantArray::get(cast<ArrayType>(ConvertType(TREE_TYPE(exp))),
                              ResultElts);
  assert(SomeVal && "If we had some initializer, we should have some value!");
  
  // Do a post-pass over all of the elements.  We're taking care of two things
  // here:
  //   #1. If any elements did not have initializers specified, provide them
  //       with a null init.
  //   #2. If any of the elements have different types, return a struct instead
  //       of an array.  This can occur in cases where we have an array of
  //       unions, and the various unions had different pieces init'd.
  const Type *ElTy = SomeVal->getType();
  Constant *Filler = Constant::getNullValue(ElTy);
  bool AllEltsSameType = true;
  for (unsigned i = 0, e = ResultElts.size(); i != e; ++i) {
    if (ResultElts[i] == 0)
      ResultElts[i] = Filler;
    else if (ResultElts[i]->getType() != ElTy)
      AllEltsSameType = false;
  }
  
  if (TREE_CODE(InitType) == VECTOR_TYPE) {
    assert(AllEltsSameType && "Vector of heterogeneous element types?");
    return ConstantVector::get(ResultElts);
  }
  
  if (AllEltsSameType)
    return ConstantArray::get(ArrayType::get(ElTy, ResultElts.size()),
                              ResultElts);
  return ConstantStruct::get(ResultElts, false);
}

/// InsertBitFieldValue - Process the assignment of a bitfield value into an
/// LLVM struct value.  Val may be null if nothing has been assigned into this
/// field, so FieldTy indicates the type of the LLVM struct type to use.
static Constant *InsertBitFieldValue(uint64_t ValToInsert,
                                     unsigned NumBitsToInsert,
                                     unsigned OffsetToBitFieldStart,
                                     unsigned FieldBitSize,
                                     Constant *Val, const Type *FieldTy) {
  if (FieldTy->isInteger()) {
    uint64_t ExistingVal;
    if (Val == 0)
      ExistingVal = 0;
    else {
      assert(isa<ConstantInt>(Val) && "Bitfield shared with non-bit-field?");
      ExistingVal = cast<ConstantInt>(Val)->getZExtValue();
    }
    
    // Compute the value to insert, and the mask to use.
    uint64_t FieldMask;
    if (BITS_BIG_ENDIAN) {
      FieldMask = ~0ULL >> (64-NumBitsToInsert);
      FieldMask   <<= FieldBitSize-(OffsetToBitFieldStart+NumBitsToInsert);
      ValToInsert <<= FieldBitSize-(OffsetToBitFieldStart+NumBitsToInsert);
    } else {
      FieldMask = ~0ULL >> (64-NumBitsToInsert);
      FieldMask   <<= OffsetToBitFieldStart;
      ValToInsert <<= OffsetToBitFieldStart;
    }

    // Insert the new value into the field and return it.
    uint64_t NewVal = (ExistingVal & ~FieldMask) | ValToInsert;
    return ConstantExpr::getTruncOrBitCast(ConstantInt::get(Type::Int64Ty, 
                                                            NewVal), FieldTy);
  } else {
    // Otherwise, this is initializing part of an array of bytes.  Recursively
    // insert each byte.
    assert(isa<ArrayType>(FieldTy) && 
           cast<ArrayType>(FieldTy)->getElementType() == Type::Int8Ty &&
           "Not an array of bytes?");
    // Expand the already parsed initializer into its elements if it is a 
    // ConstantArray or ConstantAggregateZero.
    std::vector<Constant*> Elts;
    Elts.resize(cast<ArrayType>(FieldTy)->getNumElements());
    
    if (Val) {
      if (ConstantArray *CA = dyn_cast<ConstantArray>(Val)) {
        for (unsigned i = 0, e = Elts.size(); i != e; ++i)
          Elts[i] = CA->getOperand(i);
      } else {
        assert(isa<ConstantAggregateZero>(Val) && "Unexpected initializer!");
        Constant *Elt = Constant::getNullValue(Type::Int8Ty);
        for (unsigned i = 0, e = Elts.size(); i != e; ++i)
          Elts[i] = Elt;
      }
    }
    
    // Loop over all of our elements, inserting pieces into each one as
    // appropriate.
    unsigned i = OffsetToBitFieldStart/8;  // Skip to first byte
    OffsetToBitFieldStart &= 7;
    
    for (; NumBitsToInsert; ++i) {
      assert(i < Elts.size() && "Inserting out of range!");
      
      unsigned NumEltBitsToInsert = std::min(8-OffsetToBitFieldStart,
                                             NumBitsToInsert);
      
      uint64_t EltValToInsert;
      if (BITS_BIG_ENDIAN) {
        // If this is a big-endian bit-field, take the top NumBitsToInsert
        // bits from the bitfield value.
        EltValToInsert = ValToInsert >> (NumBitsToInsert-NumEltBitsToInsert);
        
        // Clear the handled bits from BitfieldVal.
        ValToInsert &= (1ULL << (NumBitsToInsert-NumEltBitsToInsert))-1;
      } else {
        // If this is little-endian bit-field, take the bottom NumBitsToInsert
        // bits from the bitfield value.
        EltValToInsert = ValToInsert & (1ULL << NumEltBitsToInsert)-1;
        ValToInsert >>= NumEltBitsToInsert;
      }

      Elts[i] = InsertBitFieldValue(EltValToInsert, NumEltBitsToInsert,
                                    OffsetToBitFieldStart, 8, Elts[i], 
                                    Type::Int8Ty);
      
      // Advance for next element.
      OffsetToBitFieldStart = 0;
      NumBitsToInsert -= NumEltBitsToInsert;
    }

    // Pad extra array elements. This may happens when one llvm field
    // is used to access two struct fields and llvm field is represented
    // as an array of bytes.
    for (; i < Elts.size(); ++i)
      Elts[i] = ConstantInt::get((cast<ArrayType>(FieldTy))->getElementType(), 0);

    return ConstantArray::get(cast<ArrayType>(FieldTy), Elts);
  }
}


/// ProcessBitFieldInitialization - Handle a static initialization of a 
/// RECORD_TYPE field that is a bitfield.
static void ProcessBitFieldInitialization(tree Field, Value *Val,
                                          const StructType *STy,
                                          std::vector<Constant*> &ResultElts) {
  // Get the offset and size of the bitfield, in bits.
  unsigned BitfieldBitOffset = getFieldOffsetInBits(Field);
  unsigned BitfieldSize      = TREE_INT_CST_LOW(DECL_SIZE(Field));
  
  // Get the value to insert into the bitfield.
  assert(Val->getType()->isInteger() && "Bitfield initializer isn't int!");
  assert(isa<ConstantInt>(Val) && "Non-constant bitfield initializer!");
  uint64_t BitfieldVal = cast<ConstantInt>(Val)->getZExtValue();
  
  // Ensure that the top bits (which don't go into the bitfield) are zero.
  BitfieldVal &= ~0ULL >> (64-BitfieldSize);
  
  // Get the struct field layout info for this struct.
  const StructLayout *STyLayout = getTargetData().getStructLayout(STy);
  
  // If this is a bitfield, we know that FieldNo is the *first* LLVM field
  // that contains bits from the bitfield overlayed with the declared type of
  // the bitfield.  This bitfield value may be spread across multiple fields, or
  // it may be just this field, or it may just be a small part of this field.
  unsigned FieldNo = cast<ConstantInt>(DECL_LLVM(Field))->getZExtValue();
  assert(FieldNo < ResultElts.size() && "Invalid struct field number!");
  
  // Get the offset and size of the LLVM field.
  uint64_t STyFieldBitOffs = STyLayout->getElementOffset(FieldNo)*8;
  
  assert(BitfieldBitOffset >= STyFieldBitOffs &&
         "This bitfield doesn't start in this LLVM field!");
  unsigned OffsetToBitFieldStart = BitfieldBitOffset-STyFieldBitOffs;
  
  // Loop over all of the fields this bitfield is part of.  This is usually just
  // one, but can be several in some cases.
  for (; BitfieldSize; ++FieldNo) {
    assert(STyFieldBitOffs == STyLayout->getElementOffset(FieldNo)*8 &&
           "Bitfield LLVM fields are not exactly consecutive in memory!");
    
    // Compute overlap of this bitfield with this LLVM field, then call a
    // function to insert (the STy element may be an array of bytes or
    // something).
    const Type *STyFieldTy = STy->getElementType(FieldNo);
    unsigned STyFieldBitSize = getTargetData().getTypeSizeInBits(STyFieldTy);
    
    // If the bitfield starts after this field, advance to the next field.  This
    // can happen because we start looking at the first element overlapped by
    // an aligned instance of the declared type. 
    if (OffsetToBitFieldStart >= STyFieldBitSize) {
      OffsetToBitFieldStart -= STyFieldBitSize;
      STyFieldBitOffs       += STyFieldBitSize;
      continue;
    }
    
    // We are inserting part of 'Val' into this LLVM field.  The start bit
    // is OffsetToBitFieldStart.  Compute the number of bits from this bitfield
    // we are inserting into this LLVM field.
    unsigned NumBitsToInsert =
      std::min(BitfieldSize, STyFieldBitSize-OffsetToBitFieldStart);
    
    // Compute the NumBitsToInsert-wide value that we are going to insert
    // into this field as an ulong integer constant value.
    uint64_t ValToInsert;
    if (BITS_BIG_ENDIAN) {
      // If this is a big-endian bit-field, take the top NumBitsToInsert
      // bits from the bitfield value.
      ValToInsert = BitfieldVal >> (BitfieldSize-NumBitsToInsert);
      
      // Clear the handled bits from BitfieldVal.
      BitfieldVal &= (1ULL << (BitfieldSize-NumBitsToInsert))-1;
    } else {
      // If this is little-endian bit-field, take the bottom NumBitsToInsert
      // bits from the bitfield value.
      ValToInsert = BitfieldVal & (1ULL << NumBitsToInsert)-1;
      BitfieldVal >>= NumBitsToInsert;
    }
    
    ResultElts[FieldNo] = InsertBitFieldValue(ValToInsert, NumBitsToInsert,
                                              OffsetToBitFieldStart,
                                              STyFieldBitSize,
                                              ResultElts[FieldNo], STyFieldTy);
    
    // If this bitfield splits across multiple LLVM fields, update these
    // values for the next field.
    BitfieldSize          -= NumBitsToInsert;
    STyFieldBitOffs       += STyFieldBitSize;
    OffsetToBitFieldStart = 0;
  }
}

/// ConvertStructFieldInitializerToType - Convert the input value to a new type,
/// when constructing the field initializers for a constant CONSTRUCTOR object.
static Constant *ConvertStructFieldInitializerToType(Constant *Val, 
                                                     const Type *FieldTy) {
  const TargetData &TD = getTargetData();
  assert(TD.getABITypeSize(FieldTy) == TD.getABITypeSize(Val->getType()) &&
         "Mismatched initializer type isn't same size as initializer!");

  // If this is an integer initializer for an array of ubytes, we are
  // initializing an unaligned integer field.  Break the integer initializer up
  // into pieces.
  if (ConstantInt *CI = dyn_cast<ConstantInt>(Val)) {
    if (const ArrayType *ATy = dyn_cast<ArrayType>(FieldTy))
      if (ATy->getElementType() == Type::Int8Ty) {
        std::vector<Constant*> ArrayElts;
        uint64_t Val = CI->getZExtValue();
        for (unsigned i = 0, e = ATy->getNumElements(); i != e; ++i) {
          unsigned char EltVal;
         
          if (TD.isLittleEndian()) {
            EltVal = (Val >> 8*i) & 0xFF;
          } else {
            EltVal = (Val >> 8*(e-i-1)) & 0xFF;
          }
          
          ArrayElts.push_back(ConstantInt::get(Type::Int8Ty, EltVal));
        }

        return ConstantArray::get(ATy, ArrayElts);
      }
  }
  
  // Otherwise, we can get away with this initialization.
  assert(TD.getABITypeAlignment(FieldTy) >= 
         TD.getABITypeAlignment(Val->getType()) &&
         "Field initialize is over aligned for LLVM type!");
  return Val;
}


Constant *TreeConstantToLLVM::ConvertRecordCONSTRUCTOR(tree exp) {
  const StructType *STy = cast<StructType>(ConvertType(TREE_TYPE(exp)));

  std::vector<Constant*> ResultElts;
  ResultElts.resize(STy->getNumElements());

  tree NextField = TYPE_FIELDS(TREE_TYPE(exp));
  for (tree elt = CONSTRUCTOR_ELTS(exp); elt; elt = TREE_CHAIN(elt)) {
    tree Field = TREE_PURPOSE(elt);    // The fielddecl for the field.
    unsigned FieldNo;
    if (Field == 0) {           // If an explicit field is specified, use it.
      Field = NextField;
      // Advance to the next FIELD_DECL, skipping over other structure members
      // (e.g. enums).
      for (; 1; Field = TREE_CHAIN(Field)) {
        assert(Field && "Fell off end of record!");
        if (TREE_CODE(Field) == FIELD_DECL) break;
      }
    }

    // Decode the field's value.
    Constant *Val = Convert(TREE_VALUE(elt));

    // If the field is a bitfield, it could be spread across multiple fields and
    // may start at some bit offset.
    if (DECL_BIT_FIELD_TYPE(Field)) {
      ProcessBitFieldInitialization(Field, Val, STy, ResultElts);
    } else {
      // If not, things are much simpler.
      assert(DECL_LLVM_SET_P(Field) && "Struct not laid out for LLVM?");
      unsigned FieldNo = cast<ConstantInt>(DECL_LLVM(Field))->getZExtValue();
      assert(FieldNo < ResultElts.size() && "Invalid struct field number!");

      // Example: struct X { int A; char C[]; } x = { 4, "foo" };
      assert(TYPE_SIZE(TREE_TYPE(Field)) ||
             (FieldNo == ResultElts.size()-1 &&
              isStructWithVarSizeArrayAtEnd(STy))
             && "field with no size is not array at end of struct!");

      // If this is an initialization of a global that ends with a variable
      // sized array at its end, and the initializer has a non-zero number of
      // elements, then Val contains the actual type for the array.  Otherwise,
      // we know that the initializer has to match the element type of the LLVM
      // structure field.  If not, then there is something that is not
      // straight-forward going on.  For example, we could be initializing an
      // unaligned integer field (e.g. due to attribute packed) with an
      // integer.  The struct field will have type [4 x ubyte] instead of
      // "int" for example.  If we ignored this, we would lay out the
      // initializer wrong.
      if (TYPE_SIZE(TREE_TYPE(Field)) &&
          Val->getType() != STy->getElementType(FieldNo))
        Val = ConvertStructFieldInitializerToType(Val,
                                                  STy->getElementType(FieldNo));

      ResultElts[FieldNo] = Val;
    }

    NextField = TREE_CHAIN(Field);
  }
  
  // Fill in null elements with zeros.
  for (unsigned i = 0, e = ResultElts.size(); i != e; ++i)
    if (ResultElts[i] == 0)
      ResultElts[i] = Constant::getNullValue(STy->getElementType(i));
  
  return ConstantStruct::get(ResultElts, STy->isPacked());
}

Constant *TreeConstantToLLVM::ConvertUnionCONSTRUCTOR(tree exp) {
  assert(CONSTRUCTOR_ELTS(exp) && "Union CONSTRUCTOR has no elements? Zero?");
  
  tree elt = CONSTRUCTOR_ELTS(exp);
  assert(TREE_CHAIN(elt) == 0 && "Union CONSTRUCTOR with multiple elements?");

  std::vector<Constant*> Elts;
  // Convert the constant itself.
  Elts.push_back(Convert(TREE_VALUE(elt)));

  // If the union has a fixed size, and if the value we converted isn't large
  // enough to fill all the bits, add a zero initialized array at the end to pad
  // it out.
  tree UnionType = TREE_TYPE(exp);
  if (TYPE_SIZE(UnionType) && TREE_CODE(TYPE_SIZE(UnionType)) == INTEGER_CST) {
    unsigned UnionSize = ((unsigned)TREE_INT_CST_LOW(TYPE_SIZE(UnionType))+7)/8;
    unsigned InitSize = getTargetData().getABITypeSize(Elts[0]->getType());
    if (UnionSize != InitSize) {
      const Type *FillTy;
      assert(UnionSize > InitSize && "Init shouldn't be larger than union!");
      if (UnionSize - InitSize == 1)
        FillTy = Type::Int8Ty;
      else
        FillTy = ArrayType::get(Type::Int8Ty, UnionSize - InitSize);
      Elts.push_back(Constant::getNullValue(FillTy));
    }
  }
  return ConstantStruct::get(Elts, false);
}

//===----------------------------------------------------------------------===//
//                  ... Constant Expressions L-Values ...
//===----------------------------------------------------------------------===//

Constant *TreeConstantToLLVM::EmitLV(tree exp) {
  switch (TREE_CODE(exp)) {
  default: 
    debug_tree(exp); 
    assert(0 && "Unknown constant lvalue to convert!");
    abort();
  case FUNCTION_DECL:
  case CONST_DECL:
  case VAR_DECL:      return EmitLV_Decl(exp);
  case LABEL_DECL:    return EmitLV_LABEL_DECL(exp);
  case STRING_CST:    return EmitLV_STRING_CST(exp);
  case COMPONENT_REF: return EmitLV_COMPONENT_REF(exp);
  case ARRAY_RANGE_REF:
  case ARRAY_REF:     return EmitLV_ARRAY_REF(exp);
  case INDIRECT_REF:
    // The lvalue is just the address.
    return Convert(TREE_OPERAND(exp, 0));
  case COMPOUND_LITERAL_EXPR: // FIXME: not gimple - defined by C front-end
    /* This used to read 
       return EmitLV(COMPOUND_LITERAL_EXPR_DECL(exp));
       but gcc warns about that and there doesn't seem to be any way to stop it 
       with casts or the like.  The following is equivalent with no checking
       (since we know TREE_CODE(exp) is COMPOUND_LITERAL_EXPR the checking 
       doesn't accomplish anything anyway). */
    return EmitLV(DECL_EXPR_DECL (TREE_OPERAND (exp, 0)));
  }
}

Constant *TreeConstantToLLVM::EmitLV_Decl(tree exp) {
  GlobalValue *Val = cast<GlobalValue>(DECL_LLVM(exp));

  // Ensure variable marked as used even if it doesn't go through a parser.  If
  // it hasn't been used yet, write out an external definition.
  if (!TREE_USED(exp)) {
    assemble_external(exp);
    TREE_USED(exp) = 1;
    Val = cast<GlobalValue>(DECL_LLVM(exp));
  }
  
  // If this is an aggregate CONST_DECL, emit it to LLVM now.  GCC happens to
  // get this case right by forcing the initializer into memory.
  if (TREE_CODE(exp) == CONST_DECL) {
    if (DECL_INITIAL(exp) && Val->isDeclaration()) {
      emit_global_to_llvm(exp);
      // Decl could have change if it changed type.
      Val = cast<GlobalValue>(DECL_LLVM(exp));
    }
  } else {
    // Otherwise, inform cgraph that we used the global.
    mark_decl_referenced(exp);
    if (tree ID = DECL_ASSEMBLER_NAME(exp))
      mark_referenced(ID);
  }
  
  return Val;
}

/// EmitLV_LABEL_DECL - Someone took the address of a label.
Constant *TreeConstantToLLVM::EmitLV_LABEL_DECL(tree exp) {
  assert(TheTreeToLLVM &&
         "taking the address of a label while not compiling the function!");
    
  // Figure out which function this is for, verify it's the one we're compiling.
  if (DECL_CONTEXT(exp)) {
    assert(TREE_CODE(DECL_CONTEXT(exp)) == FUNCTION_DECL &&
           "Address of label in nested function?");
    assert(TheTreeToLLVM->getFUNCTION_DECL() == DECL_CONTEXT(exp) &&
           "Taking the address of a label that isn't in the current fn!?");
  }
  
  BasicBlock *BB = getLabelDeclBlock(exp);
  Constant *C = TheTreeToLLVM->getIndirectGotoBlockNumber(BB);
  return ConstantExpr::getIntToPtr(C, PointerType::getUnqual(Type::Int8Ty));
}

Constant *TreeConstantToLLVM::EmitLV_STRING_CST(tree exp) {
  Constant *Init = TreeConstantToLLVM::ConvertSTRING_CST(exp);

  // Support -fwritable-strings.
  bool StringIsConstant = !flag_writable_strings;

  GlobalVariable **SlotP = 0;

  if (StringIsConstant) {
    // Cache the string constants to avoid making obvious duplicate strings that
    // have to be folded by the optimizer.
    static std::map<Constant*, GlobalVariable*> StringCSTCache;
    GlobalVariable *&Slot = StringCSTCache[Init];
    if (Slot) return Slot;
    SlotP = &Slot;
  }
    
  // Create a new string global.
  GlobalVariable *GV = new GlobalVariable(Init->getType(), StringIsConstant,
                                          GlobalVariable::InternalLinkage,
                                          Init, ".str", TheModule);
  if (SlotP) *SlotP = GV;
  return GV;
}

Constant *TreeConstantToLLVM::EmitLV_ARRAY_REF(tree exp) {
  tree Array = TREE_OPERAND(exp, 0);
  tree ArrayType = TREE_TYPE(Array);
  tree Index = TREE_OPERAND(exp, 1);
  tree IndexType = TREE_TYPE(Index);
  assert((TREE_CODE (ArrayType) == ARRAY_TYPE ||
          TREE_CODE (ArrayType) == POINTER_TYPE ||
          TREE_CODE (ArrayType) == REFERENCE_TYPE) &&
         "Unknown ARRAY_REF!");

  // Check for variable sized reference.
  // FIXME: add support for array types where the size doesn't fit into 64 bits
  assert(isArrayCompatible(ArrayType) || isSequentialCompatible(ArrayType)
         && "Cannot have globals with variable size!");

  // As an LLVM extension, we allow ARRAY_REF with a pointer as the first
  // operand.  This construct maps directly to a getelementptr instruction.
  Constant *ArrayAddr;
  if (TREE_CODE (ArrayType) == ARRAY_TYPE) {
    // First subtract the lower bound, if any, in the type of the index.
    tree LowerBound = array_ref_low_bound(exp);
    if (!integer_zerop(LowerBound))
      Index = fold(build2(MINUS_EXPR, IndexType, Index, LowerBound));
    ArrayAddr = EmitLV(Array);
  } else {
    ArrayAddr = Convert(Array);
  }
  
  Constant *IndexVal = Convert(Index);

  const Type *IntPtrTy = getTargetData().getIntPtrType();
  if (IndexVal->getType() != IntPtrTy)
    IndexVal = ConstantExpr::getIntegerCast(IndexVal, IntPtrTy,
                                            !TYPE_UNSIGNED(IndexType));

  std::vector<Value*> Idx;
  if (isArrayCompatible(ArrayType))
    Idx.push_back(ConstantInt::get(Type::Int32Ty, 0));
  Idx.push_back(IndexVal);
  return ConstantExpr::getGetElementPtr(ArrayAddr, &Idx[0], Idx.size());
}

Constant *TreeConstantToLLVM::EmitLV_COMPONENT_REF(tree exp) {
  Constant *StructAddrLV = EmitLV(TREE_OPERAND(exp, 0));
  
  // Ensure that the struct type has been converted, so that the fielddecls
  // are laid out.
  const Type *StructTy = ConvertType(TREE_TYPE(TREE_OPERAND(exp, 0)));
  
  tree FieldDecl = TREE_OPERAND(exp, 1);
  
  StructAddrLV = ConstantExpr::getBitCast(StructAddrLV,
                                          PointerType::getUnqual(StructTy));
  const Type *FieldTy = ConvertType(TREE_TYPE(FieldDecl));
  
  // BitStart - This is the actual offset of the field from the start of the
  // struct, in bits.  For bitfields this may be on a non-byte boundary.
  unsigned BitStart = getComponentRefOffsetInBits(exp);
  unsigned BitSize  = 0;
  Constant *FieldPtr;
  const TargetData &TD = getTargetData();

  tree field_offset = component_ref_field_offset (exp);
  // If this is a normal field at a fixed offset from the start, handle it.
  if (TREE_CODE(field_offset) == INTEGER_CST) {
    assert(DECL_LLVM_SET_P(FieldDecl) && "Struct not laid out for LLVM?");
    ConstantInt *CI = cast<ConstantInt>(DECL_LLVM(FieldDecl));
    uint64_t MemberIndex = CI->getZExtValue();
    
    std::vector<Value*> Idxs;
    Idxs.push_back(Constant::getNullValue(Type::Int32Ty));
    Idxs.push_back(CI);
    FieldPtr = ConstantExpr::getGetElementPtr(StructAddrLV, &Idxs[0],
                                              Idxs.size());
    
    // Now that we did an offset from the start of the struct, subtract off
    // the offset from BitStart.
    if (MemberIndex) {
      const StructLayout *SL = TD.getStructLayout(cast<StructType>(StructTy));
      BitStart -= SL->getElementOffset(MemberIndex) * 8;
    }
  } else {
    Constant *Offset = Convert(field_offset);
    Constant *Ptr = ConstantExpr::getPtrToInt(StructAddrLV, Offset->getType());
    Ptr = ConstantExpr::getAdd(Ptr, Offset);
    FieldPtr = ConstantExpr::getIntToPtr(Ptr, PointerType::getUnqual(FieldTy));
  }
  
  if (DECL_BIT_FIELD_TYPE(FieldDecl)) {
    FieldTy = ConvertType(DECL_BIT_FIELD_TYPE(FieldDecl));
    FieldPtr = ConstantExpr::getBitCast(FieldPtr, 
                                        PointerType::getUnqual(FieldTy));
  }
  
  assert(BitStart == 0 &&
         "It's a bitfield reference or we didn't get to the field!");
  return FieldPtr;
}

/* APPLE LOCAL end LLVM (ENTIRE FILE!)  */