llvm/lib/Target/Sparc/SparcRegInfo.cpp

//===-- SparcRegInfo.cpp - Sparc Target Register Information --------------===//
//
// This file contains implementation of Sparc specific helper methods
// used for register allocation.
//
//===----------------------------------------------------------------------===//

#include "SparcInternals.h"
#include "SparcRegClassInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFunctionInfo.h"
#include "llvm/CodeGen/PhyRegAlloc.h"
#include "llvm/CodeGen/InstrSelection.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineInstrAnnot.h"
#include "llvm/CodeGen/FunctionLiveVarInfo.h"   // FIXME: Remove
#include "../../CodeGen/RegAlloc/RegAllocCommon.h"   // FIXME!
#include "llvm/iTerminators.h"
#include "llvm/iOther.h"
#include "llvm/Function.h"
#include "llvm/DerivedTypes.h"

enum {
  BadRegClass = ~0
};

UltraSparcRegInfo::UltraSparcRegInfo(const UltraSparc &tgt)
  : TargetRegInfo(tgt), NumOfIntArgRegs(6), 
    NumOfFloatArgRegs(32), InvalidRegNum(1000) {
   
  MachineRegClassArr.push_back(new SparcIntRegClass(IntRegClassID));
  MachineRegClassArr.push_back(new SparcFloatRegClass(FloatRegClassID));
  MachineRegClassArr.push_back(new SparcIntCCRegClass(IntCCRegClassID));
  MachineRegClassArr.push_back(new SparcFloatCCRegClass(FloatCCRegClassID));
  MachineRegClassArr.push_back(new SparcSpecialRegClass(SpecialRegClassID));
  
  assert(SparcFloatRegClass::StartOfNonVolatileRegs == 32 && 
         "32 Float regs are used for float arg passing");
}


// getZeroRegNum - returns the register that contains always zero.
// this is the unified register number
//
int UltraSparcRegInfo::getZeroRegNum() const {
  return getUnifiedRegNum(UltraSparcRegInfo::IntRegClassID,
                          SparcIntRegClass::g0);
}

// getCallAddressReg - returns the reg used for pushing the address when a
// method is called. This can be used for other purposes between calls
//
unsigned UltraSparcRegInfo::getCallAddressReg() const {
  return getUnifiedRegNum(UltraSparcRegInfo::IntRegClassID,
                          SparcIntRegClass::o7);
}

// Returns the register containing the return address.
// It should be made sure that this  register contains the return 
// value when a return instruction is reached.
//
unsigned UltraSparcRegInfo::getReturnAddressReg() const {
  return getUnifiedRegNum(UltraSparcRegInfo::IntRegClassID,
                          SparcIntRegClass::i7);
}

// Register get name implementations...

// Int register names in same order as enum in class SparcIntRegClass
static const char * const IntRegNames[] = {
  "o0", "o1", "o2", "o3", "o4", "o5",       "o7",
  "l0", "l1", "l2", "l3", "l4", "l5", "l6", "l7",
  "i0", "i1", "i2", "i3", "i4", "i5",  
  "i6", "i7",
  "g0", "g1", "g2", "g3", "g4", "g5",  "g6", "g7", 
  "o6"
}; 

const char * const SparcIntRegClass::getRegName(unsigned reg) const {
  assert(reg < NumOfAllRegs);
  return IntRegNames[reg];
}

static const char * const FloatRegNames[] = {    
  "f0",  "f1",  "f2",  "f3",  "f4",  "f5",  "f6",  "f7",  "f8",  "f9", 
  "f10", "f11", "f12", "f13", "f14", "f15", "f16", "f17", "f18", "f19",
  "f20", "f21", "f22", "f23", "f24", "f25", "f26", "f27", "f28", "f29",
  "f30", "f31", "f32", "f33", "f34", "f35", "f36", "f37", "f38", "f39",
  "f40", "f41", "f42", "f43", "f44", "f45", "f46", "f47", "f48", "f49",
  "f50", "f51", "f52", "f53", "f54", "f55", "f56", "f57", "f58", "f59",
  "f60", "f61", "f62", "f63"
};

const char * const SparcFloatRegClass::getRegName(unsigned reg) const {
  assert (reg < NumOfAllRegs);
  return FloatRegNames[reg];
}


static const char * const IntCCRegNames[] = {    
  "xcc",  "ccr"
};

const char * const SparcIntCCRegClass::getRegName(unsigned reg) const {
  assert(reg < 2);
  return IntCCRegNames[reg];
}

static const char * const FloatCCRegNames[] = {    
  "fcc0", "fcc1",  "fcc2",  "fcc3"
};

const char * const SparcFloatCCRegClass::getRegName(unsigned reg) const {
  assert (reg < 5);
  return FloatCCRegNames[reg];
}

static const char * const SpecialRegNames[] = {    
  "fsr"
};

const char * const SparcSpecialRegClass::getRegName(unsigned reg) const {
  assert (reg < 1);
  return SpecialRegNames[reg];
}

// Get unified reg number for frame pointer
unsigned UltraSparcRegInfo::getFramePointer() const {
  return getUnifiedRegNum(UltraSparcRegInfo::IntRegClassID,
                          SparcIntRegClass::i6);
}

// Get unified reg number for stack pointer
unsigned UltraSparcRegInfo::getStackPointer() const {
  return getUnifiedRegNum(UltraSparcRegInfo::IntRegClassID,
                          SparcIntRegClass::o6);
}


//---------------------------------------------------------------------------
// Finds whether a call is an indirect call
//---------------------------------------------------------------------------

inline bool
isVarArgsFunction(const Type *funcType) {
  return cast<FunctionType>(cast<PointerType>(funcType)
                            ->getElementType())->isVarArg();
}

inline bool
isVarArgsCall(const MachineInstr *CallMI) {
  Value* callee = CallMI->getOperand(0).getVRegValue();
  // const Type* funcType = isa<Function>(callee)? callee->getType()
  //   : cast<PointerType>(callee->getType())->getElementType();
  const Type* funcType = callee->getType();
  return isVarArgsFunction(funcType);
}


// Get the register number for the specified integer arg#,
// assuming there are argNum total args, intArgNum int args,
// and fpArgNum FP args preceding (and not including) this one.
// Use INT regs for FP args if this is a varargs call.
// 
// Return value:
//      InvalidRegNum,  if there is no int register available for the arg. 
//      regNum,         otherwise (this is NOT the unified reg. num).
// 
inline int
UltraSparcRegInfo::regNumForIntArg(bool inCallee, bool isVarArgsCall,
                                   unsigned argNo,
                                   unsigned intArgNo, unsigned fpArgNo,
                                   unsigned& regClassId) const
{
  regClassId = IntRegClassID;
  if (argNo >= NumOfIntArgRegs)
    return InvalidRegNum;
  else
    return argNo + (inCallee? SparcIntRegClass::i0 : SparcIntRegClass::o0);
}

// Get the register number for the specified FP arg#,
// assuming there are argNum total args, intArgNum int args,
// and fpArgNum FP args preceding (and not including) this one.
// Use INT regs for FP args if this is a varargs call.
// 
// Return value:
//      InvalidRegNum,  if there is no int register available for the arg. 
//      regNum,         otherwise (this is NOT the unified reg. num).
// 
inline int
UltraSparcRegInfo::regNumForFPArg(unsigned regType,
                                  bool inCallee, bool isVarArgsCall,
                                  unsigned argNo,
                                  unsigned intArgNo, unsigned fpArgNo,
                                  unsigned& regClassId) const
{
  if (isVarArgsCall)
    return regNumForIntArg(inCallee, isVarArgsCall, argNo, intArgNo, fpArgNo,
                           regClassId);
  else
    {
      regClassId = FloatRegClassID;
      if (regType == FPSingleRegType)
        return (argNo*2+1 >= NumOfFloatArgRegs)?
          InvalidRegNum : SparcFloatRegClass::f0 + (argNo * 2 + 1);
      else if (regType == FPDoubleRegType)
        return (argNo*2 >= NumOfFloatArgRegs)?
          InvalidRegNum : SparcFloatRegClass::f0 + (argNo * 2);
      else
        assert(0 && "Illegal FP register type");
	return 0;
    }
}


//---------------------------------------------------------------------------
// Finds the return address of a call sparc specific call instruction
//---------------------------------------------------------------------------

// The following 4  methods are used to find the RegType (SparcInternals.h)
// of a LiveRange, a Value, and for a given register unified reg number.
//
int UltraSparcRegInfo::getRegTypeForClassAndType(unsigned regClassID,
                                                 const Type* type) const
{
  switch (regClassID) {
  case IntRegClassID:                   return IntRegType; 
  case FloatRegClassID:
    if (type == Type::FloatTy)          return FPSingleRegType;
    else if (type == Type::DoubleTy)    return FPDoubleRegType;
    assert(0 && "Unknown type in FloatRegClass"); return 0;
  case IntCCRegClassID:                 return IntCCRegType; 
  case FloatCCRegClassID:               return FloatCCRegType; 
  case SpecialRegClassID:               return SpecialRegType; 
  default: assert( 0 && "Unknown reg class ID"); return 0;
  }
}

int UltraSparcRegInfo::getRegType(const Type* type) const
{
  return getRegTypeForClassAndType(getRegClassIDOfType(type), type);
}

int UltraSparcRegInfo::getRegType(const LiveRange *LR) const
{
  return getRegTypeForClassAndType(LR->getRegClassID(), LR->getType());
}

int UltraSparcRegInfo::getRegType(int unifiedRegNum) const
{
  if (unifiedRegNum < 32) 
    return IntRegType;
  else if (unifiedRegNum < (32 + 32))
    return FPSingleRegType;
  else if (unifiedRegNum < (64 + 32))
    return FPDoubleRegType;
  else if (unifiedRegNum < (64+32+4))
    return FloatCCRegType;
  else if (unifiedRegNum < (64+32+4+2))  
    return IntCCRegType;             
  else 
    assert(0 && "Invalid unified register number in getRegType");
  return 0;
}


// To find the register class used for a specified Type
//
unsigned UltraSparcRegInfo::getRegClassIDOfType(const Type *type,
                                                bool isCCReg) const {
  Type::PrimitiveID ty = type->getPrimitiveID();
  unsigned res;
    
  // FIXME: Comparing types like this isn't very safe...
  if ((ty && ty <= Type::LongTyID) || (ty == Type::LabelTyID) ||
      (ty == Type::FunctionTyID) ||  (ty == Type::PointerTyID) )
    res = IntRegClassID;             // sparc int reg (ty=0: void)
  else if (ty <= Type::DoubleTyID)
    res = FloatRegClassID;           // sparc float reg class
  else { 
    //std::cerr << "TypeID: " << ty << "\n";
    assert(0 && "Cannot resolve register class for type");
    return 0;
  }
  
  if (isCCReg)
    return res + 2;      // corresponding condition code register 
  else 
    return res;
}

unsigned UltraSparcRegInfo::getRegClassIDOfRegType(int regType) const {
  switch(regType) {
  case IntRegType:      return IntRegClassID;
  case FPSingleRegType:
  case FPDoubleRegType: return FloatRegClassID;
  case IntCCRegType:    return IntCCRegClassID;
  case FloatCCRegType:  return FloatCCRegClassID;
  default:
    assert(0 && "Invalid register type in getRegClassIDOfRegType");
    return 0;
  }
}

//---------------------------------------------------------------------------
// Suggests a register for the ret address in the RET machine instruction.
// We always suggest %i7 by convention.
//---------------------------------------------------------------------------
void UltraSparcRegInfo::suggestReg4RetAddr(MachineInstr *RetMI, 
					   LiveRangeInfo& LRI) const {

  assert(target.getInstrInfo().isReturn(RetMI->getOpCode()));
  
  // return address is always mapped to i7 so set it immediately
  RetMI->SetRegForOperand(0, getUnifiedRegNum(IntRegClassID,
                                              SparcIntRegClass::i7));
  
  // Possible Optimization: 
  // Instead of setting the color, we can suggest one. In that case,
  // we have to test later whether it received the suggested color.
  // In that case, a LR has to be created at the start of method.
  // It has to be done as follows (remove the setRegVal above):

  // MachineOperand & MO  = RetMI->getOperand(0);
  // const Value *RetAddrVal = MO.getVRegValue();
  // assert( RetAddrVal && "LR for ret address must be created at start");
  // LiveRange * RetAddrLR = LRI.getLiveRangeForValue( RetAddrVal);  
  // RetAddrLR->setSuggestedColor(getUnifiedRegNum( IntRegClassID, 
  //                              SparcIntRegOrdr::i7) );
}


//---------------------------------------------------------------------------
// Suggests a register for the ret address in the JMPL/CALL machine instr.
// Sparc ABI dictates that %o7 be used for this purpose.
//---------------------------------------------------------------------------
void
UltraSparcRegInfo::suggestReg4CallAddr(MachineInstr * CallMI,
                                       LiveRangeInfo& LRI) const
{
  CallArgsDescriptor* argDesc = CallArgsDescriptor::get(CallMI); 
  const Value *RetAddrVal = argDesc->getReturnAddrReg();
  assert(RetAddrVal && "INTERNAL ERROR: Return address value is required");

  // A LR must already exist for the return address.
  LiveRange *RetAddrLR = LRI.getLiveRangeForValue(RetAddrVal);
  assert(RetAddrLR && "INTERNAL ERROR: No LR for return address of call!");

  unsigned RegClassID = RetAddrLR->getRegClassID();
  RetAddrLR->setColor(getUnifiedRegNum(IntRegClassID, SparcIntRegClass::o7));
}



//---------------------------------------------------------------------------
//  This method will suggest colors to incoming args to a method. 
//  According to the Sparc ABI, the first 6 incoming args are in 
//  %i0 - %i5 (if they are integer) OR in %f0 - %f31 (if they are float).
//  If the arg is passed on stack due to the lack of regs, NOTHING will be
//  done - it will be colored (or spilled) as a normal live range.
//---------------------------------------------------------------------------
void UltraSparcRegInfo::suggestRegs4MethodArgs(const Function *Meth, 
					       LiveRangeInfo& LRI) const 
{
  // check if this is a varArgs function. needed for choosing regs.
  bool isVarArgs = isVarArgsFunction(Meth->getType());
  
  // for each argument.  count INT and FP arguments separately.
  unsigned argNo=0, intArgNo=0, fpArgNo=0;
  for(Function::const_aiterator I = Meth->abegin(), E = Meth->aend();
      I != E; ++I, ++argNo) {
    // get the LR of arg
    LiveRange *LR = LRI.getLiveRangeForValue(I);
    assert(LR && "No live range found for method arg");
    
    unsigned regType = getRegType(LR);
    unsigned regClassIDOfArgReg = BadRegClass; // reg class of chosen reg (unused)
    
    int regNum = (regType == IntRegType)
      ? regNumForIntArg(/*inCallee*/ true, isVarArgs,
                        argNo, intArgNo++, fpArgNo, regClassIDOfArgReg)
      : regNumForFPArg(regType, /*inCallee*/ true, isVarArgs,
                       argNo, intArgNo, fpArgNo++, regClassIDOfArgReg); 
    
    if(regNum != InvalidRegNum)
      LR->setSuggestedColor(regNum);
  }
}


//---------------------------------------------------------------------------
// This method is called after graph coloring to move incoming args to
// the correct hardware registers if they did not receive the correct
// (suggested) color through graph coloring.
//---------------------------------------------------------------------------
void UltraSparcRegInfo::colorMethodArgs(const Function *Meth, 
					LiveRangeInfo &LRI,
					AddedInstrns *FirstAI) const {

  // check if this is a varArgs function. needed for choosing regs.
  bool isVarArgs = isVarArgsFunction(Meth->getType());
  MachineInstr *AdMI;

  // for each argument
  // for each argument.  count INT and FP arguments separately.
  unsigned argNo=0, intArgNo=0, fpArgNo=0;
  for(Function::const_aiterator I = Meth->abegin(), E = Meth->aend();
      I != E; ++I, ++argNo) {
    // get the LR of arg
    LiveRange *LR = LRI.getLiveRangeForValue(I);
    assert( LR && "No live range found for method arg");

    unsigned regType = getRegType(LR);
    unsigned RegClassID = LR->getRegClassID();
    
    // Find whether this argument is coming in a register (if not, on stack)
    // Also find the correct register the argument must use (UniArgReg)
    //
    bool isArgInReg = false;
    unsigned UniArgReg = InvalidRegNum;	// reg that LR MUST be colored with
    unsigned regClassIDOfArgReg = BadRegClass; // reg class of chosen reg
    
    int regNum = (regType == IntRegType)
      ? regNumForIntArg(/*inCallee*/ true, isVarArgs,
                        argNo, intArgNo++, fpArgNo, regClassIDOfArgReg)
      : regNumForFPArg(regType, /*inCallee*/ true, isVarArgs,
                       argNo, intArgNo, fpArgNo++, regClassIDOfArgReg);
    
    if(regNum != InvalidRegNum) {
      isArgInReg = true;
      UniArgReg = getUnifiedRegNum( regClassIDOfArgReg, regNum);
    }
    
    if( LR->hasColor() ) {              // if this arg received a register

      unsigned UniLRReg = getUnifiedRegNum(  RegClassID, LR->getColor() );

      // if LR received the correct color, nothing to do
      //
      if( UniLRReg == UniArgReg )
	continue;

      // We are here because the LR did not receive the suggested 
      // but LR received another register.
      // Now we have to copy the %i reg (or stack pos of arg) 
      // to the register the LR was colored with.
      
      // if the arg is coming in UniArgReg register, it MUST go into
      // the UniLRReg register
      //
      if( isArgInReg ) {
	if( regClassIDOfArgReg != RegClassID ) {
          assert(0 && "This could should work but it is not tested yet");
          
	  // It is a variable argument call: the float reg must go in a %o reg.
	  // We have to move an int reg to a float reg via memory.
          // 
          assert(isVarArgs &&
                 RegClassID == FloatRegClassID && 
                 regClassIDOfArgReg == IntRegClassID &&
                 "This should only be an Int register for an FP argument");
          
 	  int TmpOff = MachineFunction::get(Meth).getInfo()->pushTempValue(
                                                getSpilledRegSize(regType));
	  cpReg2MemMI(FirstAI->InstrnsBefore,
                      UniArgReg, getFramePointer(), TmpOff, IntRegType);
          
	  cpMem2RegMI(FirstAI->InstrnsBefore,
                      getFramePointer(), TmpOff, UniLRReg, regType);
	}
	else {	
	  cpReg2RegMI(FirstAI->InstrnsBefore, UniArgReg, UniLRReg, regType);
	}
      }
      else {

	// Now the arg is coming on stack. Since the LR recieved a register,
	// we just have to load the arg on stack into that register
	//
        const TargetFrameInfo& frameInfo = target.getFrameInfo();
	int offsetFromFP =
          frameInfo.getIncomingArgOffset(MachineFunction::get(Meth),
                                         argNo);
        
	cpMem2RegMI(FirstAI->InstrnsBefore,
                    getFramePointer(), offsetFromFP, UniLRReg, regType);
      }
      
    } // if LR received a color

    else {                             

      // Now, the LR did not receive a color. But it has a stack offset for
      // spilling.
      // So, if the arg is coming in UniArgReg register,  we can just move
      // that on to the stack pos of LR

      if( isArgInReg ) {
        
	if( regClassIDOfArgReg != RegClassID ) {
          assert(0 &&
                 "FP arguments to a varargs function should be explicitly "
                 "copied to/from int registers by instruction selection!");
          
	  // It must be a float arg for a variable argument call, which
          // must come in a %o reg.  Move the int reg to the stack.
          // 
          assert(isVarArgs && regClassIDOfArgReg == IntRegClassID &&
                 "This should only be an Int register for an FP argument");
          
          cpReg2MemMI(FirstAI->InstrnsBefore, UniArgReg,
                      getFramePointer(), LR->getSpillOffFromFP(), IntRegType);
        }
        else {
           cpReg2MemMI(FirstAI->InstrnsBefore, UniArgReg,
                       getFramePointer(), LR->getSpillOffFromFP(), regType);
        }
      }

      else {

	// Now the arg is coming on stack. Since the LR did NOT 
	// recieved a register as well, it is allocated a stack position. We
	// can simply change the stack position of the LR. We can do this,
	// since this method is called before any other method that makes
	// uses of the stack pos of the LR (e.g., updateMachineInstr)

        const TargetFrameInfo& frameInfo = target.getFrameInfo();
	int offsetFromFP =
          frameInfo.getIncomingArgOffset(MachineFunction::get(Meth),
                                         argNo);
        
	LR->modifySpillOffFromFP( offsetFromFP );
      }

    }

  }  // for each incoming argument

}



//---------------------------------------------------------------------------
// This method is called before graph coloring to suggest colors to the
// outgoing call args and the return value of the call.
//---------------------------------------------------------------------------
void UltraSparcRegInfo::suggestRegs4CallArgs(MachineInstr *CallMI, 
					     LiveRangeInfo& LRI) const {
  assert ( (target.getInstrInfo()).isCall(CallMI->getOpCode()) );

  CallArgsDescriptor* argDesc = CallArgsDescriptor::get(CallMI); 
  
  suggestReg4CallAddr(CallMI, LRI);

  // First color the return value of the call instruction, if any.
  // The return value will be in %o0 if the value is an integer type,
  // or in %f0 if the value is a float type.
  // 
  if (const Value *RetVal = argDesc->getReturnValue()) {
    LiveRange *RetValLR = LRI.getLiveRangeForValue(RetVal);
    assert(RetValLR && "No LR for return Value of call!");

    unsigned RegClassID = RetValLR->getRegClassID();

    // now suggest a register depending on the register class of ret arg
    if( RegClassID == IntRegClassID ) 
      RetValLR->setSuggestedColor(SparcIntRegClass::o0);
    else if (RegClassID == FloatRegClassID ) 
      RetValLR->setSuggestedColor(SparcFloatRegClass::f0 );
    else assert( 0 && "Unknown reg class for return value of call\n");
  }

  // Now suggest colors for arguments (operands) of the call instruction.
  // Colors are suggested only if the arg number is smaller than the
  // the number of registers allocated for argument passing.
  // Now, go thru call args - implicit operands of the call MI

  unsigned NumOfCallArgs = argDesc->getNumArgs();
  
  for(unsigned argNo=0, i=0, intArgNo=0, fpArgNo=0;
       i < NumOfCallArgs; ++i, ++argNo) {    

    const Value *CallArg = argDesc->getArgInfo(i).getArgVal();
    
    // get the LR of call operand (parameter)
    LiveRange *const LR = LRI.getLiveRangeForValue(CallArg); 
    assert (LR && "Must have a LR for all arguments since "
                  "all args (even consts) must be defined before");

    unsigned regType = getRegType(LR);
    unsigned regClassIDOfArgReg = BadRegClass; // reg class of chosen reg (unused)

    // Choose a register for this arg depending on whether it is
    // an INT or FP value.  Here we ignore whether or not it is a
    // varargs calls, because FP arguments will be explicitly copied
    // to an integer Value and handled under (argCopy != NULL) below.
    int regNum = (regType == IntRegType)
      ? regNumForIntArg(/*inCallee*/ false, /*isVarArgs*/ false,
                        argNo, intArgNo++, fpArgNo, regClassIDOfArgReg)
      : regNumForFPArg(regType, /*inCallee*/ false, /*isVarArgs*/ false,
                       argNo, intArgNo, fpArgNo++, regClassIDOfArgReg); 
    
    // If a register could be allocated, use it.
    // If not, do NOTHING as this will be colored as a normal value.
    if(regNum != InvalidRegNum)
      LR->setSuggestedColor(regNum);
    
    // Repeat for the second copy of the argument, which would be
    // an FP argument being passed to a function with no prototype
    const Value *argCopy = argDesc->getArgInfo(i).getArgCopy();
    if (argCopy != NULL)
      {
        assert(regType != IntRegType && argCopy->getType()->isInteger()
               && "Must be passing copy of FP argument in int register");
        int copyRegNum = regNumForIntArg(/*inCallee*/false, /*isVarArgs*/false,
                                         argNo, intArgNo, fpArgNo-1,
                                         regClassIDOfArgReg);
        assert(copyRegNum != InvalidRegNum); 
        LiveRange *const copyLR = LRI.getLiveRangeForValue(argCopy); 
        copyLR->setSuggestedColor(copyRegNum);
      }
    
  } // for all call arguments

}


//---------------------------------------------------------------------------
// Helper method for UltraSparcRegInfo::colorCallArgs().
//---------------------------------------------------------------------------
    
void
UltraSparcRegInfo::InitializeOutgoingArg(MachineInstr* CallMI,
                             AddedInstrns *CallAI,
                             PhyRegAlloc &PRA, LiveRange* LR,
                             unsigned regType, unsigned RegClassID,
                             int UniArgRegOrNone, unsigned argNo,
                             std::vector<MachineInstr*> &AddedInstrnsBefore)
  const
{
  MachineInstr *AdMI;
  bool isArgInReg = false;
  unsigned UniArgReg = BadRegClass;          // unused unless initialized below
  if (UniArgRegOrNone != InvalidRegNum)
    {
      isArgInReg = true;
      UniArgReg = (unsigned) UniArgRegOrNone;
      CallMI->insertUsedReg(UniArgReg); // mark the reg as used
    }
  
  if (LR->hasColor()) {
    unsigned UniLRReg = getUnifiedRegNum(RegClassID, LR->getColor());
    
    // if LR received the correct color, nothing to do
    if( isArgInReg && UniArgReg == UniLRReg )
      return;
    
    // The LR is allocated to a register UniLRReg and must be copied
    // to UniArgReg or to the stack slot.
    // 
    if( isArgInReg ) {
      // Copy UniLRReg to UniArgReg
      cpReg2RegMI(AddedInstrnsBefore, UniLRReg, UniArgReg, regType);
    }
    else {
      // Copy UniLRReg to the stack to pass the arg on stack.
      const TargetFrameInfo& frameInfo = target.getFrameInfo();
      int argOffset = frameInfo.getOutgoingArgOffset(PRA.MF, argNo);
      cpReg2MemMI(CallAI->InstrnsBefore,
                  UniLRReg, getStackPointer(), argOffset, regType);
    }

  } else {                          // LR is not colored (i.e., spilled)      
    
    if( isArgInReg ) {
      // Insert a load instruction to load the LR to UniArgReg
      cpMem2RegMI(AddedInstrnsBefore, getFramePointer(),
                  LR->getSpillOffFromFP(), UniArgReg, regType);
                                        // Now add the instruction
    }
      
    else {
      // Now, we have to pass the arg on stack. Since LR  also did NOT
      // receive a register we have to move an argument in memory to 
      // outgoing parameter on stack.
      // Use TReg to load and store the value.
      // Use TmpOff to save TReg, since that may have a live value.
      // 
      int TReg = PRA.getUniRegNotUsedByThisInst(LR->getRegClass(), CallMI);
      int TmpOff = PRA.MF.getInfo()->
	             pushTempValue(getSpilledRegSize(getRegType(LR)));
      const TargetFrameInfo& frameInfo = target.getFrameInfo();
      int argOffset = frameInfo.getOutgoingArgOffset(PRA.MF, argNo);
      
      MachineInstr *Ad1, *Ad2, *Ad3, *Ad4;
        
      // Sequence:
      // (1) Save TReg on stack    
      // (2) Load LR value into TReg from stack pos of LR
      // (3) Store Treg on outgoing Arg pos on stack
      // (4) Load the old value of TReg from stack to TReg (restore it)
      // 
      // OPTIMIZE THIS:
      // When reverse pointers in MahineInstr are introduced: 
      // Call PRA.getUnusedRegAtMI(....) to get an unused reg. Step 1 is
      // needed only if this fails. Currently, we cannot call the
      // above method since we cannot find LVSetBefore without the BB 
      // 
      // NOTE: We directly add to CallAI->InstrnsBefore instead of adding to
      // AddedInstrnsBefore since these instructions must not be reordered.
      cpReg2MemMI(CallAI->InstrnsBefore,
                  TReg, getFramePointer(), TmpOff, regType);
      cpMem2RegMI(CallAI->InstrnsBefore,
                  getFramePointer(), LR->getSpillOffFromFP(), TReg, regType); 
      cpReg2MemMI(CallAI->InstrnsBefore,
                  TReg, getStackPointer(), argOffset, regType);
      cpMem2RegMI(CallAI->InstrnsBefore,
                  getFramePointer(), TmpOff, TReg, regType); 
    }
  }
}

//---------------------------------------------------------------------------
// After graph coloring, we have call this method to see whehter the return
// value and the call args received the correct colors. If not, we have
// to instert copy instructions.
//---------------------------------------------------------------------------

void UltraSparcRegInfo::colorCallArgs(MachineInstr *CallMI,
				      LiveRangeInfo &LRI,
				      AddedInstrns *CallAI,
				      PhyRegAlloc &PRA,
				      const BasicBlock *BB) const {

  assert ( (target.getInstrInfo()).isCall(CallMI->getOpCode()) );

  CallArgsDescriptor* argDesc = CallArgsDescriptor::get(CallMI); 
  
  // First color the return value of the call.
  // If there is a LR for the return value, it means this
  // method returns a value
  
  MachineInstr *AdMI;

  const Value *RetVal = argDesc->getReturnValue();

  if (RetVal) {
    LiveRange *RetValLR = LRI.getLiveRangeForValue( RetVal );

    if (!RetValLR) {
      std::cerr << "\nNo LR for:" << RAV(RetVal) << "\n";
      assert(RetValLR && "ERR:No LR for non-void return value");
    }

    unsigned RegClassID = RetValLR->getRegClassID();
    bool recvCorrectColor;
    unsigned CorrectCol;                // correct color for ret value
    unsigned UniRetReg;                 // unified number for CorrectCol
    
    if(RegClassID == IntRegClassID)
      CorrectCol = SparcIntRegClass::o0;
    else if(RegClassID == FloatRegClassID)
      CorrectCol = SparcFloatRegClass::f0;
    else {
      assert( 0 && "Unknown RegClass");
      return;
    }
    
    // convert to unified number
    UniRetReg = getUnifiedRegNum(RegClassID, CorrectCol);	

    // Mark the register as used by this instruction
    CallMI->insertUsedReg(UniRetReg);
    
    // if the LR received the correct color, NOTHING to do
    recvCorrectColor = RetValLR->hasColor()? RetValLR->getColor() == CorrectCol
      : false;
    
    // if we didn't receive the correct color for some reason, 
    // put copy instruction
    if( !recvCorrectColor ) {
      
      unsigned regType = getRegType(RetValLR);

      if( RetValLR->hasColor() ) {
	
	unsigned UniRetLRReg=getUnifiedRegNum(RegClassID,RetValLR->getColor());
	
	// the return value is coming in UniRetReg but has to go into
	// the UniRetLRReg

	cpReg2RegMI(CallAI->InstrnsAfter, UniRetReg, UniRetLRReg, regType);

      } // if LR has color
      else {

	// if the LR did NOT receive a color, we have to move the return
	// value coming in UniRetReg to the stack pos of spilled LR
	
        cpReg2MemMI(CallAI->InstrnsAfter, UniRetReg,
                    getFramePointer(),RetValLR->getSpillOffFromFP(), regType);
      }

    } // the LR didn't receive the suggested color  
    
  } // if there a return value
  

  //-------------------------------------------
  // Now color all args of the call instruction
  //-------------------------------------------

  std::vector<MachineInstr*> AddedInstrnsBefore;
  
  unsigned NumOfCallArgs = argDesc->getNumArgs();
  
  for(unsigned argNo=0, i=0, intArgNo=0, fpArgNo=0;
      i < NumOfCallArgs; ++i, ++argNo) {    

    const Value *CallArg = argDesc->getArgInfo(i).getArgVal();
    
    // get the LR of call operand (parameter)
    LiveRange *const LR = LRI.getLiveRangeForValue(CallArg); 

    unsigned RegClassID = getRegClassIDOfType(CallArg->getType());
    unsigned regType = getRegType(CallArg->getType());
    
    // Find whether this argument is coming in a register (if not, on stack)
    // Also find the correct register the argument must use (UniArgReg)
    //
    bool isArgInReg = false;
    unsigned UniArgReg = InvalidRegNum;	  // reg that LR MUST be colored with
    unsigned regClassIDOfArgReg = BadRegClass; // reg class of chosen reg
    
    // Find the register that must be used for this arg, depending on
    // whether it is an INT or FP value.  Here we ignore whether or not it
    // is a varargs calls, because FP arguments will be explicitly copied
    // to an integer Value and handled under (argCopy != NULL) below.
    int regNum = (regType == IntRegType)
      ? regNumForIntArg(/*inCallee*/ false, /*isVarArgs*/ false,
                        argNo, intArgNo++, fpArgNo, regClassIDOfArgReg)
      : regNumForFPArg(regType, /*inCallee*/ false, /*isVarArgs*/ false,
                       argNo, intArgNo, fpArgNo++, regClassIDOfArgReg); 
    
    if(regNum != InvalidRegNum) {
      isArgInReg = true;
      UniArgReg = getUnifiedRegNum( regClassIDOfArgReg, regNum);
      assert(regClassIDOfArgReg == RegClassID &&
             "Moving values between reg classes must happen during selection");
    }
    
    // not possible to have a null LR since all args (even consts)  
    // must be defined before
    if (!LR) {          
      std::cerr <<" ERROR: In call instr, no LR for arg: " <<RAV(CallArg)<<"\n";
      assert(LR && "NO LR for call arg");  
    }
    
    InitializeOutgoingArg(CallMI, CallAI, PRA, LR, regType, RegClassID,
                          UniArgReg, argNo, AddedInstrnsBefore);
    
    // Repeat for the second copy of the argument, which would be
    // an FP argument being passed to a function with no prototype.
    // It may either be passed as a copy in an integer register
    // (in argCopy), or on the stack (useStackSlot).
    const Value *argCopy = argDesc->getArgInfo(i).getArgCopy();
    if (argCopy != NULL)
      {
        assert(regType != IntRegType && argCopy->getType()->isInteger()
               && "Must be passing copy of FP argument in int register");
        
        unsigned copyRegClassID = getRegClassIDOfType(argCopy->getType());
        unsigned copyRegType = getRegType(argCopy->getType());
        
        int copyRegNum = regNumForIntArg(/*inCallee*/false, /*isVarArgs*/false,
                                         argNo, intArgNo, fpArgNo-1,
                                         regClassIDOfArgReg);
        assert(copyRegNum != InvalidRegNum); 
        assert(regClassIDOfArgReg == copyRegClassID &&
           "Moving values between reg classes must happen during selection");
        
        InitializeOutgoingArg(CallMI, CallAI, PRA,
                              LRI.getLiveRangeForValue(argCopy), copyRegType,
                              copyRegClassID, copyRegNum, argNo,
                              AddedInstrnsBefore);
      }
    
    if (regNum != InvalidRegNum &&
        argDesc->getArgInfo(i).usesStackSlot())
      {
        // Pass the argument via the stack in addition to regNum
        assert(regType != IntRegType && "Passing an integer arg. twice?");
        assert(!argCopy && "Passing FP arg in FP reg, INT reg, and stack?");
        InitializeOutgoingArg(CallMI, CallAI, PRA, LR, regType, RegClassID,
                              InvalidRegNum, argNo, AddedInstrnsBefore);
      }
  }  // for each parameter in call instruction

  // If we added any instruction before the call instruction, verify
  // that they are in the proper order and if not, reorder them
  // 
  std::vector<MachineInstr*> ReorderedVec;
  if (!AddedInstrnsBefore.empty()) {

    if (DEBUG_RA) {
      std::cerr << "\nCalling reorder with instrns: \n";
      for(unsigned i=0; i < AddedInstrnsBefore.size(); i++)
	std::cerr  << *(AddedInstrnsBefore[i]);
    }

    OrderAddedInstrns(AddedInstrnsBefore, ReorderedVec, PRA);
    assert(ReorderedVec.size() >= AddedInstrnsBefore.size()
           && "Dropped some instructions when reordering!");
    
    if (DEBUG_RA) {
      std::cerr << "\nAfter reordering instrns: \n";
      for(unsigned i = 0; i < ReorderedVec.size(); i++)
	std::cerr << *ReorderedVec[i];
    }
  }
  
  // Now insert caller saving code for this call instruction
  //
  insertCallerSavingCode(CallAI->InstrnsBefore, CallAI->InstrnsAfter,
                         CallMI, BB, PRA);
  
  // Then insert the final reordered code for the call arguments.
  // 
  for(unsigned i=0; i < ReorderedVec.size(); i++)
    CallAI->InstrnsBefore.push_back( ReorderedVec[i] );
}

//---------------------------------------------------------------------------
// This method is called for an LLVM return instruction to identify which
// values will be returned from this method and to suggest colors.
//---------------------------------------------------------------------------
void UltraSparcRegInfo::suggestReg4RetValue(MachineInstr *RetMI, 
                                            LiveRangeInfo &LRI) const {

  assert( (target.getInstrInfo()).isReturn( RetMI->getOpCode() ) );

  suggestReg4RetAddr(RetMI, LRI);

  // if there is an implicit ref, that has to be the ret value
  if(  RetMI->getNumImplicitRefs() > 0 ) {

    // The first implicit operand is the return value of a return instr
    const Value *RetVal =  RetMI->getImplicitRef(0);

    LiveRange *const LR = LRI.getLiveRangeForValue( RetVal ); 

    if (!LR) {
      std::cerr << "\nNo LR for:" << RAV(RetVal) << "\n";
      assert(0 && "No LR for return value of non-void method");
    }

    unsigned RegClassID = LR->getRegClassID();
    if (RegClassID == IntRegClassID) 
      LR->setSuggestedColor(SparcIntRegClass::i0);
    else if (RegClassID == FloatRegClassID) 
      LR->setSuggestedColor(SparcFloatRegClass::f0);
  }
}



//---------------------------------------------------------------------------
// Colors the return value of a method to %i0 or %f0, if possible. If it is
// not possilbe to directly color the LR, insert a copy instruction to move
// the LR to %i0 or %f0. When the LR is spilled, instead of the copy, we 
// have to put a load instruction.
//---------------------------------------------------------------------------
void UltraSparcRegInfo::colorRetValue(MachineInstr *RetMI, 
				      LiveRangeInfo &LRI,
				      AddedInstrns *RetAI) const {

  assert((target.getInstrInfo()).isReturn( RetMI->getOpCode()));

  // if there is an implicit ref, that has to be the ret value
  if(RetMI->getNumImplicitRefs() > 0) {

    // The first implicit operand is the return value of a return instr
    const Value *RetVal =  RetMI->getImplicitRef(0);

    LiveRange *LR = LRI.getLiveRangeForValue(RetVal); 

    if (!LR) {
      std::cerr << "\nNo LR for:" << RAV(RetVal) << "\n";
      // assert( LR && "No LR for return value of non-void method");
      return;
    }

    unsigned RegClassID = getRegClassIDOfType(RetVal->getType());
    unsigned regType = getRegType(RetVal->getType());

    unsigned CorrectCol;
    if(RegClassID == IntRegClassID)
      CorrectCol = SparcIntRegClass::i0;
    else if(RegClassID == FloatRegClassID)
      CorrectCol = SparcFloatRegClass::f0;
    else {
      assert (0 && "Unknown RegClass");
      return;
    }

    // convert to unified number
    unsigned UniRetReg = getUnifiedRegNum(RegClassID, CorrectCol);

    // Mark the register as used by this instruction
    RetMI->insertUsedReg(UniRetReg);
    
    // if the LR received the correct color, NOTHING to do
    
    if (LR->hasColor() && LR->getColor() == CorrectCol)
      return;
    
    if (LR->hasColor()) {

      // We are here because the LR was allocted a regiter
      // It may be the suggested register or not

      // copy the LR of retun value to i0 or f0

      unsigned UniLRReg =getUnifiedRegNum( RegClassID, LR->getColor());

      // the LR received  UniLRReg but must be colored with UniRetReg
      // to pass as the return value
      cpReg2RegMI(RetAI->InstrnsBefore, UniLRReg, UniRetReg, regType);
    }
    else {                              // if the LR is spilled
      cpMem2RegMI(RetAI->InstrnsBefore, getFramePointer(),
                  LR->getSpillOffFromFP(), UniRetReg, regType);
      //std::cerr << "\nCopied the return value from stack\n";
    }
  
  } // if there is a return value

}

//---------------------------------------------------------------------------
// Check if a specified register type needs a scratch register to be
// copied to/from memory.  If it does, the reg. type that must be used
// for scratch registers is returned in scratchRegType.
//
// Only the int CC register needs such a scratch register.
// The FP CC registers can (and must) be copied directly to/from memory.
//---------------------------------------------------------------------------

bool
UltraSparcRegInfo::regTypeNeedsScratchReg(int RegType,
                                          int& scratchRegType) const
{
  if (RegType == IntCCRegType)
    {
      scratchRegType = IntRegType;
      return true;
    }
  return false;
}

//---------------------------------------------------------------------------
// Copy from a register to register. Register number must be the unified
// register number.
//---------------------------------------------------------------------------

void
UltraSparcRegInfo::cpReg2RegMI(std::vector<MachineInstr*>& mvec,
                               unsigned SrcReg,
                               unsigned DestReg,
                               int RegType) const {
  assert( ((int)SrcReg != InvalidRegNum) && ((int)DestReg != InvalidRegNum) &&
	  "Invalid Register");
  
  MachineInstr * MI = NULL;
  
  switch( RegType ) {
    
  case IntCCRegType:
    if (getRegType(DestReg) == IntRegType) {
      // copy intCC reg to int reg
      // Use SrcReg+1 to get the name "%ccr" instead of "%xcc" for RDCCR
      MI = BuildMI(V9::RDCCR, 2).addMReg(SrcReg+1).addMReg(DestReg,MOTy::Def);
    } else {
      // copy int reg to intCC reg
      // Use DestReg+1 to get the name "%ccr" instead of "%xcc" for WRCCR
      assert(getRegType(SrcReg) == IntRegType
             && "Can only copy CC reg to/from integer reg");
      MI = BuildMI(V9::WRCCR, 2).addMReg(SrcReg).addMReg(DestReg+1, MOTy::Def);
    }
    break;
    
  case FloatCCRegType: 
    assert(0 && "Cannot copy FPCC register to any other register");
    break;
    
  case IntRegType:
    MI = BuildMI(V9::ADDr, 3).addMReg(SrcReg).addMReg(getZeroRegNum())
      .addMReg(DestReg, MOTy::Def);
    break;
    
  case FPSingleRegType:
    MI = BuildMI(V9::FMOVS, 2).addMReg(SrcReg).addMReg(DestReg, MOTy::Def);
    break;

  case FPDoubleRegType:
    MI = BuildMI(V9::FMOVD, 2).addMReg(SrcReg).addMReg(DestReg, MOTy::Def);
    break;

  default:
    assert(0 && "Unknown RegType");
    break;
  }
  
  if (MI)
    mvec.push_back(MI);
}

//---------------------------------------------------------------------------
// Copy from a register to memory (i.e., Store). Register number must 
// be the unified register number
//---------------------------------------------------------------------------


void
UltraSparcRegInfo::cpReg2MemMI(std::vector<MachineInstr*>& mvec,
                               unsigned SrcReg, 
                               unsigned DestPtrReg,
                               int Offset, int RegType,
                               int scratchReg) const {
  MachineInstr * MI = NULL;
  switch (RegType) {
  case IntRegType:
    assert(target.getInstrInfo().constantFitsInImmedField(V9::STXi, Offset));
    MI = BuildMI(V9::STXi,3).addMReg(SrcReg).addMReg(DestPtrReg)
      .addSImm(Offset);
    break;

  case FPSingleRegType:
    assert(target.getInstrInfo().constantFitsInImmedField(V9::STFi, Offset));
    MI = BuildMI(V9::STFi, 3).addMReg(SrcReg).addMReg(DestPtrReg)
      .addSImm(Offset);
    break;

  case FPDoubleRegType:
    assert(target.getInstrInfo().constantFitsInImmedField(V9::STDFi, Offset));
    MI = BuildMI(V9::STDFi,3).addMReg(SrcReg).addMReg(DestPtrReg)
      .addSImm(Offset);
    break;

  case IntCCRegType:
    assert(scratchReg >= 0 && "Need scratch reg to store %ccr to memory");
    assert(getRegType(scratchReg) ==IntRegType && "Invalid scratch reg");
    
    // Use SrcReg+1 to get the name "%ccr" instead of "%xcc" for RDCCR
    MI = BuildMI(V9::RDCCR, 2).addMReg(SrcReg+1).addMReg(scratchReg, MOTy::Def);
    mvec.push_back(MI);
    
    cpReg2MemMI(mvec, scratchReg, DestPtrReg, Offset, IntRegType);
    return;
    
  case FloatCCRegType: {
    assert(target.getInstrInfo().constantFitsInImmedField(V9::STXFSRi, Offset));
    unsigned fsrRegNum =  getUnifiedRegNum(UltraSparcRegInfo::SpecialRegClassID,
                                           SparcSpecialRegClass::fsr);
    MI = BuildMI(V9::STXFSRi, 3)
      .addMReg(fsrRegNum).addMReg(DestPtrReg).addSImm(Offset);
    break;
  }
  default:
    assert(0 && "Unknown RegType in cpReg2MemMI");
  }
  mvec.push_back(MI);
}


//---------------------------------------------------------------------------
// Copy from memory to a reg (i.e., Load) Register number must be the unified
// register number
//---------------------------------------------------------------------------


void
UltraSparcRegInfo::cpMem2RegMI(std::vector<MachineInstr*>& mvec,
                               unsigned SrcPtrReg,	
                               int Offset,
                               unsigned DestReg,
                               int RegType,
                               int scratchReg) const {
  MachineInstr * MI = NULL;
  switch (RegType) {
  case IntRegType:
    assert(target.getInstrInfo().constantFitsInImmedField(V9::LDXi, Offset));
    MI = BuildMI(V9::LDXi, 3).addMReg(SrcPtrReg).addSImm(Offset)
      .addMReg(DestReg, MOTy::Def);
    break;

  case FPSingleRegType:
    assert(target.getInstrInfo().constantFitsInImmedField(V9::LDFi, Offset));
    MI = BuildMI(V9::LDFi, 3).addMReg(SrcPtrReg).addSImm(Offset)
      .addMReg(DestReg, MOTy::Def);
    break;

  case FPDoubleRegType:
    assert(target.getInstrInfo().constantFitsInImmedField(V9::LDDFi, Offset));
    MI = BuildMI(V9::LDDFi, 3).addMReg(SrcPtrReg).addSImm(Offset)
      .addMReg(DestReg, MOTy::Def);
    break;

  case IntCCRegType:
    assert(scratchReg >= 0 && "Need scratch reg to load %ccr from memory");
    assert(getRegType(scratchReg) ==IntRegType && "Invalid scratch reg");
    cpMem2RegMI(mvec, SrcPtrReg, Offset, scratchReg, IntRegType);
    
    // Use DestReg+1 to get the name "%ccr" instead of "%xcc" for WRCCR
    MI = BuildMI(V9::WRCCR, 2).addMReg(scratchReg).addMReg(DestReg+1,MOTy::Def);
    break;
    
  case FloatCCRegType: {
    assert(target.getInstrInfo().constantFitsInImmedField(V9::LDXFSRi, Offset));
    unsigned fsrRegNum =  getUnifiedRegNum(UltraSparcRegInfo::SpecialRegClassID,
                                           SparcSpecialRegClass::fsr);
    MI = BuildMI(V9::LDXFSRi, 3).addMReg(SrcPtrReg).addSImm(Offset)
      .addMReg(fsrRegNum, MOTy::UseAndDef);
    break;
  }
  default:
    assert(0 && "Unknown RegType in cpMem2RegMI");
  }
  mvec.push_back(MI);
}


//---------------------------------------------------------------------------
// Generate a copy instruction to copy a value to another. Temporarily
// used by PhiElimination code.
//---------------------------------------------------------------------------


void
UltraSparcRegInfo::cpValue2Value(Value *Src, Value *Dest,
                                 std::vector<MachineInstr*>& mvec) const {
  int RegType = getRegType(Src->getType());
  MachineInstr * MI = NULL;

  switch( RegType ) {
  case IntRegType:
    MI = BuildMI(V9::ADDr, 3).addReg(Src).addMReg(getZeroRegNum())
      .addRegDef(Dest);
    break;
  case FPSingleRegType:
    MI = BuildMI(V9::FMOVS, 2).addReg(Src).addRegDef(Dest);
    break;
  case FPDoubleRegType:
    MI = BuildMI(V9::FMOVD, 2).addReg(Src).addRegDef(Dest);
    break;
  default:
    assert(0 && "Unknow RegType in CpValu2Value");
  }

  mvec.push_back(MI);
}






//----------------------------------------------------------------------------
// This method inserts caller saving/restoring instructons before/after
// a call machine instruction. The caller saving/restoring instructions are
// inserted like:
//
//    ** caller saving instructions
//    other instructions inserted for the call by ColorCallArg
//    CALL instruction
//    other instructions inserted for the call ColorCallArg
//    ** caller restoring instructions
//
//----------------------------------------------------------------------------


void
UltraSparcRegInfo::insertCallerSavingCode
(std::vector<MachineInstr*> &instrnsBefore,
 std::vector<MachineInstr*> &instrnsAfter,
 MachineInstr *CallMI, 
 const BasicBlock *BB,
 PhyRegAlloc &PRA) const
{
  assert ( (target.getInstrInfo()).isCall(CallMI->getOpCode()) );
  
  // has set to record which registers were saved/restored
  //
  hash_set<unsigned> PushedRegSet;

  CallArgsDescriptor* argDesc = CallArgsDescriptor::get(CallMI);
  
  // Now find the LR of the return value of the call
  // The last *implicit operand* is the return value of a call
  // Insert it to to he PushedRegSet since we must not save that register
  // and restore it after the call.
  // We do this because, we look at the LV set *after* the instruction
  // to determine, which LRs must be saved across calls. The return value
  // of the call is live in this set - but we must not save/restore it.

  const Value *RetVal = argDesc->getReturnValue();

  if (RetVal) {
    LiveRange *RetValLR = PRA.LRI.getLiveRangeForValue( RetVal );
    assert(RetValLR && "No LR for RetValue of call");

    if (RetValLR->hasColor())
      PushedRegSet.insert(getUnifiedRegNum(RetValLR->getRegClassID(),
                                           RetValLR->getColor()));
  }

  const ValueSet &LVSetAft =  PRA.LVI->getLiveVarSetAfterMInst(CallMI, BB);
  ValueSet::const_iterator LIt = LVSetAft.begin();

  // for each live var in live variable set after machine inst
  for( ; LIt != LVSetAft.end(); ++LIt) {

   //  get the live range corresponding to live var
    LiveRange *const LR = PRA.LRI.getLiveRangeForValue(*LIt );    

    // LR can be null if it is a const since a const 
    // doesn't have a dominating def - see Assumptions above
    if( LR )   {  
      
      if( LR->hasColor() ) {

	unsigned RCID = LR->getRegClassID();
	unsigned Color = LR->getColor();

	if ( isRegVolatile(RCID, Color) ) {

	  // if the value is in both LV sets (i.e., live before and after 
	  // the call machine instruction)
          
	  unsigned Reg = getUnifiedRegNum(RCID, Color);
	  
	  if( PushedRegSet.find(Reg) == PushedRegSet.end() ) {
	    
	    // if we haven't already pushed that register

	    unsigned RegType = getRegType(LR);

	    // Now get two instructions - to push on stack and pop from stack
	    // and add them to InstrnsBefore and InstrnsAfter of the
	    // call instruction
            // 
	    int StackOff = 
	      PRA.MF.getInfo()->pushTempValue(getSpilledRegSize(RegType));
            
	    std::vector<MachineInstr*> AdIBef, AdIAft;
            
	    //---- Insert code for pushing the reg on stack ----------
            
            // We may need a scratch register to copy the saved value
            // to/from memory.  This may itself have to insert code to
            // free up a scratch register.  Any such code should go before
            // the save code.
            int scratchRegType = -1;
            int scratchReg = -1;
            if (regTypeNeedsScratchReg(RegType, scratchRegType))
              { // Find a register not live in the LVSet before CallMI
                const ValueSet &LVSetBef =
                  PRA.LVI->getLiveVarSetBeforeMInst(CallMI, BB);
                scratchReg = PRA.getUsableUniRegAtMI(scratchRegType, &LVSetBef,
                                                   CallMI, AdIBef, AdIAft);
                assert(scratchReg != getInvalidRegNum());
                CallMI->insertUsedReg(scratchReg); 
              }
            
            if (AdIBef.size() > 0)
              instrnsBefore.insert(instrnsBefore.end(),
                                   AdIBef.begin(), AdIBef.end());
            
            cpReg2MemMI(instrnsBefore, Reg,getFramePointer(),StackOff,RegType,
                        scratchReg);
            
            if (AdIAft.size() > 0)
              instrnsBefore.insert(instrnsBefore.end(),
                                   AdIAft.begin(), AdIAft.end());
            
	    //---- Insert code for popping the reg from the stack ----------

            // We may need a scratch register to copy the saved value
            // from memory.  This may itself have to insert code to
            // free up a scratch register.  Any such code should go
            // after the save code.
            // 
            scratchRegType = -1;
            scratchReg = -1;
            if (regTypeNeedsScratchReg(RegType, scratchRegType))
              { // Find a register not live in the LVSet after CallMI
                scratchReg = PRA.getUsableUniRegAtMI(scratchRegType, &LVSetAft,
                                                 CallMI, AdIBef, AdIAft);
                assert(scratchReg != getInvalidRegNum());
                CallMI->insertUsedReg(scratchReg); 
              }
            
            if (AdIBef.size() > 0)
              instrnsAfter.insert(instrnsAfter.end(),
                                  AdIBef.begin(), AdIBef.end());
            
	    cpMem2RegMI(instrnsAfter, getFramePointer(), StackOff,Reg,RegType,
                        scratchReg);
            
            if (AdIAft.size() > 0)
              instrnsAfter.insert(instrnsAfter.end(),
                                  AdIAft.begin(), AdIAft.end());
	    
	    PushedRegSet.insert(Reg);
            
	    if(DEBUG_RA) {
	      std::cerr << "\nFor call inst:" << *CallMI;
	      std::cerr << " -inserted caller saving instrs: Before:\n\t ";
              for_each(instrnsBefore.begin(), instrnsBefore.end(),
                       std::mem_fun(&MachineInstr::dump));
	      std::cerr << " -and After:\n\t ";
              for_each(instrnsAfter.begin(), instrnsAfter.end(),
                       std::mem_fun(&MachineInstr::dump));
	    }	    
	  } // if not already pushed

	} // if LR has a volatile color
	
      } // if LR has color

    } // if there is a LR for Var
    
  } // for each value in the LV set after instruction
}


//---------------------------------------------------------------------------
// Print the register assigned to a LR
//---------------------------------------------------------------------------

void UltraSparcRegInfo::printReg(const LiveRange *LR) const {
  unsigned RegClassID = LR->getRegClassID();
  std::cerr << " *Node " << (LR->getUserIGNode())->getIndex();

  if (!LR->hasColor()) {
    std::cerr << " - could not find a color\n";
    return;
  }
  
  // if a color is found

  std::cerr << " colored with color "<< LR->getColor();

  unsigned uRegName = getUnifiedRegNum(RegClassID, LR->getColor());
  
  std::cerr << "[";
  std::cerr<< getUnifiedRegName(uRegName);
  if (RegClassID == FloatRegClassID && LR->getType() == Type::DoubleTy)
    std::cerr << "+" << getUnifiedRegName(uRegName+1);
  std::cerr << "]\n";
}

//---------------------------------------------------------------------------
// This method examines instructions inserted by RegAlloc code before a
// machine instruction to detect invalid orders that destroy values before
// they are used. If it detects such conditions, it reorders the instructions.
//
// The unordered instructions come in the UnordVec. These instructions are
// instructions inserted by RegAlloc. All such instruction MUST have 
// their USES BEFORE THE DEFS after reordering.
// 
// The UnordVec & OrdVec must be DISTINCT. The OrdVec must be empty when
// this method is called.
// 
// This method uses two vectors for efficiency in accessing
// 
// Since instructions are inserted in RegAlloc, this assumes that the 
// first operand is the source reg and the last operand is the dest reg.
// It also does not consider operands that are both use and def.
// 
// All the uses are before THE def to a register
//---------------------------------------------------------------------------

void UltraSparcRegInfo::OrderAddedInstrns(std::vector<MachineInstr*> &UnordVec,
					  std::vector<MachineInstr*> &OrdVec,
                                          PhyRegAlloc &PRA) const{

  /*
    Problem: We can have instructions inserted by RegAlloc like
    1. add %ox %g0 %oy
    2. add %oy %g0 %oz, where z!=x or z==x

    This is wrong since %oy used by 2 is overwritten by 1
  
    Solution:
    We re-order the instructions so that the uses are before the defs

    Algorithm:
    
    do
      for each instruction 'DefInst' in the UnOrdVec
         for each instruction 'UseInst' that follows the DefInst
           if the reg defined by DefInst is used by UseInst
	     mark DefInst as not movable in this iteration
	 If DefInst is not marked as not-movable, move DefInst to OrdVec
    while all instructions in DefInst are moved to OrdVec
    
    For moving, we call the move2OrdVec(). It checks whether there is a def
    in it for the uses in the instruction to be added to OrdVec. If there
    are no preceding defs, it just appends the instruction. If there is a
    preceding def, it puts two instructions to save the reg on stack before
    the load and puts a restore at use.

  */

  bool CouldMoveAll;
  bool DebugPrint = false;

  do {
    CouldMoveAll = true;
    std::vector<MachineInstr*>::iterator DefIt = UnordVec.begin();

    for( ; DefIt !=  UnordVec.end(); ++DefIt ) {

      // for each instruction in the UnordVec do ...

      MachineInstr *DefInst = *DefIt;

      if( DefInst == NULL) continue;

      //std::cerr << "\nInst in UnordVec = " <<  *DefInst;
      
      // last operand is the def (unless for a store which has no def reg)
      MachineOperand& DefOp = DefInst->getOperand(DefInst->getNumOperands()-1);
      
      if ((DefOp.opIsDefOnly() || DefOp.opIsDefAndUse()) &&
          DefOp.getType() == MachineOperand::MO_MachineRegister) {
	
	// If the operand in DefInst is a def ...
	bool DefEqUse = false;
	
	std::vector<MachineInstr*>::iterator UseIt = DefIt;
	UseIt++;
	
	for( ; UseIt !=  UnordVec.end(); ++UseIt ) {

	  MachineInstr *UseInst = *UseIt;
	  if( UseInst == NULL) continue;
	  
	  // for each inst (UseInst) that is below the DefInst do ...
	  MachineOperand& UseOp = UseInst->getOperand(0);
	  
	  if (!UseOp.opIsDefOnly() &&  
	      UseOp.getType() == MachineOperand::MO_MachineRegister) {
	    
	    // if use is a register ...
	    
	    if( DefOp.getMachineRegNum() == UseOp.getMachineRegNum() ) {
	      
	      // if Def and this use are the same, it means that this use
	      // is destroyed by a def before it is used
	      
	      // std::cerr << "\nCouldn't move " << *DefInst;

	      DefEqUse = true;
	      CouldMoveAll = false;	
	      DebugPrint = true;
	      break;
	    } // if two registers are equal
	    
	  } // if use is a register
	  
	}// for all use instructions
	
	if( ! DefEqUse ) {
	  
	  // after examining all the instructions that follow the DefInst
	  // if there are no dependencies, we can move it to the OrdVec

	  // std::cerr << "Moved to Ord: " << *DefInst;

	  moveInst2OrdVec(OrdVec, DefInst, PRA);

	  //OrdVec.push_back(DefInst);

	  // mark the pos of DefInst with NULL to indicate that it is
	  // empty
	  *DefIt = NULL;
	}
    
      } // if Def is a machine register
      
    } // for all instructions in the UnordVec
    

  } while(!CouldMoveAll);

  if (DebugPrint && DEBUG_RA) {
    std::cerr << "\nAdded instructions were reordered to:\n";
    for(unsigned i=0; i < OrdVec.size(); i++)
      std::cerr << *OrdVec[i];
  }
}





void UltraSparcRegInfo::moveInst2OrdVec(std::vector<MachineInstr*> &OrdVec,
					MachineInstr *UnordInst,
					PhyRegAlloc &PRA) const {
  MachineOperand& UseOp = UnordInst->getOperand(0);

  if (!UseOp.opIsDefOnly() &&
      UseOp.getType() ==  MachineOperand::MO_MachineRegister) {

    // for the use of UnordInst, see whether there is a defining instr
    // before in the OrdVec
    bool DefEqUse = false;

    std::vector<MachineInstr*>::iterator OrdIt = OrdVec.begin();
  
    for( ; OrdIt !=  OrdVec.end(); ++OrdIt ) {

      MachineInstr *OrdInst = *OrdIt ;

      MachineOperand& DefOp = 
	OrdInst->getOperand(OrdInst->getNumOperands()-1);

      if( (DefOp.opIsDefOnly() || DefOp.opIsDefAndUse()) &&  
	  DefOp.getType() == MachineOperand::MO_MachineRegister) {

	//std::cerr << "\nDefining Ord Inst: " <<  *OrdInst;
	  
	if( DefOp.getMachineRegNum() == UseOp.getMachineRegNum() ) {

	  // we are here because there is a preceding def in the OrdVec 
	  // for the use in this intr we are going to insert. This
	  // happened because the original code was like:
	  // 1. add %ox %g0 %oy
	  // 2. add %oy %g0 %ox
	  // In Round1, we added 2 to OrdVec but 1 remained in UnordVec
	  // Now we are processing %ox of 1.
	  // We have to 
	      
	  int UReg = DefOp.getMachineRegNum();
	  int RegType = getRegType(UReg);
	  MachineInstr *AdIBef, *AdIAft;
	      
	  int StackOff =
	    PRA.MF.getInfo()->pushTempValue(getSpilledRegSize(RegType));
	  
	  // Save the UReg (%ox) on stack before it's destroyed
          std::vector<MachineInstr*> mvec;
	  cpReg2MemMI(mvec, UReg, getFramePointer(), StackOff, RegType);
          for (std::vector<MachineInstr*>::iterator MI=mvec.begin();
	       MI != mvec.end(); ++MI)
            OrdIt = 1+OrdVec.insert(OrdIt, *MI);
	  
	  // Load directly into DReg (%oy)
	  MachineOperand&  DOp=
	    (UnordInst->getOperand(UnordInst->getNumOperands()-1));
	  assert((DOp.opIsDefOnly() || DefOp.opIsDefAndUse()) &&
                 "Last operand is not the def");
	  const int DReg = DOp.getMachineRegNum();
	  
	  cpMem2RegMI(OrdVec, getFramePointer(), StackOff, DReg, RegType);
	    
	  if( DEBUG_RA ) {
            std::cerr << "\nFixed CIRCULAR references by reordering:";
	    std::cerr << "\nBefore CIRCULAR Reordering:\n";
	    std::cerr << *UnordInst;
	    std::cerr << *OrdInst;
	  
	    std::cerr << "\nAfter CIRCULAR Reordering - All Inst so far:\n";
	    for(unsigned i=0; i < OrdVec.size(); i++)
	      std::cerr << *(OrdVec[i]);
	  }
	  
	  // Do not copy the UseInst to OrdVec
	  DefEqUse = true;
	  break;  
	  
	}// if two registers are equal

      } // if Def is a register

    } // for each instr in OrdVec

    if(!DefEqUse) {  

      // We didn't find a def in the OrdVec, so just append this inst
      OrdVec.push_back( UnordInst );  
      //std::cerr << "Reordered Inst (Moved Dn): " <<  *UnordInst;
    }
    
  }// if the operand in UnordInst is a use
}