llvm/lib/Target/Sparc/SparcRegInfo.cpp

#include "llvm/Target/Sparc.h"
#include "SparcInternals.h"
#include "llvm/Method.h"
#include "llvm/iTerminators.h"
#include "llvm/iOther.h"
#include "llvm/CodeGen/InstrScheduling.h"
#include "llvm/CodeGen/InstrSelection.h"

#include "llvm/Analysis/LiveVar/MethodLiveVarInfo.h"
#include "llvm/CodeGen/PhyRegAlloc.h"




//---------------------------------------------------------------------------
// UltraSparcRegInfo
//---------------------------------------------------------------------------

//---------------------------------------------------------------------------
// Finds the return value of a call instruction
//---------------------------------------------------------------------------

const Value * 
UltraSparcRegInfo::getCallInstRetVal(const MachineInstr *CallMI) const{

  unsigned OpCode = CallMI->getOpCode();
  unsigned NumOfImpRefs =  CallMI->getNumImplicitRefs();

  if( OpCode == CALL ) {

    // The one before the last implicit operand is the return value of 
    // a CALL instr
    if( NumOfImpRefs > 1 )
      if(  CallMI->implicitRefIsDefined(NumOfImpRefs-2) ) 
	return  CallMI->getImplicitRef(NumOfImpRefs-2); 

  }
  else if( OpCode == JMPLCALL) {

    // The last implicit operand is the return value of a JMPL in   
    if( NumOfImpRefs > 0 )
      if(  CallMI->implicitRefIsDefined(NumOfImpRefs-1) ) 
	return  CallMI->getImplicitRef(NumOfImpRefs-1); 
  }
  else
    assert(0 && "OpCode must be CALL/JMPL for a call instr");

  return NULL;

}

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

const Value *
UltraSparcRegInfo::getCallInstRetAddr(const MachineInstr *CallMI)const {

  unsigned OpCode = CallMI->getOpCode();

  if( OpCode == CALL) {

    unsigned NumOfImpRefs =  CallMI->getNumImplicitRefs();

    assert( NumOfImpRefs && "CALL instr must have at least on ImpRef");
    // The last implicit operand is the return address of a CALL instr
    return  CallMI->getImplicitRef(NumOfImpRefs-1); 

  }
  else if( OpCode == JMPLCALL ) {

    MachineOperand & MO  = ( MachineOperand &) CallMI->getOperand(2);
    return MO.getVRegValue();

  }
  else
    assert(0 && "OpCode must be CALL/JMPL for a call instr");

  assert(0  && "There must be a return addr for a call instr");

  return NULL;

}


//---------------------------------------------------------------------------
// Finds the # of actual arguments of the call instruction
//---------------------------------------------------------------------------

const unsigned 
UltraSparcRegInfo::getCallInstNumArgs(const MachineInstr *CallMI) const {

  unsigned OpCode = CallMI->getOpCode();
  unsigned NumOfImpRefs =  CallMI->getNumImplicitRefs();
  int NumArgs = -1;

  if( OpCode == CALL ) {

    switch( NumOfImpRefs ) {

    case 0: assert(0 && "A CALL inst must have at least one ImpRef (RetAddr)");

    case 1: NumArgs = 0;
            break;
    
    default:  // two or more implicit refs
      if(  CallMI->implicitRefIsDefined(NumOfImpRefs-2) ) 
	NumArgs = NumOfImpRefs - 2;    // i.e., NumOfImpRef-2 is the ret val
      else 
	NumArgs = NumOfImpRefs - 1;
    }

  }
  else if( OpCode == JMPLCALL ) {

    // The last implicit operand is the return value of a JMPL instr
    if( NumOfImpRefs > 0 ) {
      if(  CallMI->implicitRefIsDefined(NumOfImpRefs-1) ) 
	NumArgs = NumOfImpRefs - 1;    // i.e., NumOfImpRef-1 is the ret val
      else 
	NumArgs = NumOfImpRefs;
    }
    else 
      NumArgs = NumOfImpRefs;
  }
  else
    assert(0 && "OpCode must be CALL/JMPL for a call instr");

  assert( (NumArgs != -1)  && "Internal error in getCallInstNumArgs" );
  return (unsigned) NumArgs;
 
  
}


//---------------------------------------------------------------------------
// Suggests a register for the ret address in the RET machine instruction
//---------------------------------------------------------------------------

void UltraSparcRegInfo::suggestReg4RetAddr(const MachineInstr * RetMI, 
					   LiveRangeInfo& LRI) const {

  assert( (RetMI->getNumOperands() >= 2)
          && "JMPL/RETURN must have 3 and 2 operands respectively");
  
  MachineOperand & MO  = ( MachineOperand &) RetMI->getOperand(0);

  MO.setRegForValue( getUnifiedRegNum( IntRegClassID, SparcIntRegOrder::i7) );
  
  // TODO (Optimize): 
  // 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):

  /*
  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
//---------------------------------------------------------------------------
void UltraSparcRegInfo::suggestReg4CallAddr(const MachineInstr * CallMI,
					    LiveRangeInfo& LRI,
					    vector<RegClass *> RCList) const {


  const Value *RetAddrVal = getCallInstRetAddr( CallMI );

  // RetAddrVal cannot be NULL (asserted in  getCallInstRetAddr)
  // create a new LR for the return address and color it
  
  LiveRange * RetAddrLR = new LiveRange();  
  RetAddrLR->add( RetAddrVal );
  unsigned RegClassID = getRegClassIDOfValue( RetAddrVal );
  RetAddrLR->setRegClass( RCList[RegClassID] );
  RetAddrLR->setColor(getUnifiedRegNum(IntRegClassID,SparcIntRegOrder::o7));
  LRI.addLRToMap( RetAddrVal, RetAddrLR);
  

  /*  
  assert( (CallMI->getNumOperands() == 3) && "JMPL must have 3 operands");

  // directly set color since the LR of ret address (if there were one) 
  // will not extend after the call instr

  MachineOperand & MO  = ( MachineOperand &) CallMI->getOperand(2);
  MO.setRegForValue( getUnifiedRegNum( IntRegClassID,SparcIntRegOrder::o7) );

  */

}




//---------------------------------------------------------------------------
//  This method will suggest colors to incoming args to a method. 
//  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 value.
//---------------------------------------------------------------------------

void UltraSparcRegInfo::suggestRegs4MethodArgs(const Method *const Meth, 
					       LiveRangeInfo& LRI) const 
{

                                                 // get the argument list
  const Method::ArgumentListType& ArgList = Meth->getArgumentList();           
                                                 // get an iterator to arg list
  Method::ArgumentListType::const_iterator ArgIt = ArgList.begin(); 

  // for each argument
  for( unsigned argNo=0; ArgIt != ArgList.end() ; ++ArgIt, ++argNo) {    

    // get the LR of arg
    LiveRange *const LR = LRI.getLiveRangeForValue((const Value *) *ArgIt); 
    assert( LR && "No live range found for method arg");

    unsigned RegType = getRegType( LR );


    // if the arg is in int class - allocate a reg for an int arg
    if( RegType == IntRegType ) {

      if( argNo < NumOfIntArgRegs) {
	LR->setSuggestedColor( SparcIntRegOrder::i0 + argNo );

      }
  
      else {
	// Do NOTHING as this will be colored as a normal value.
	if (DEBUG_RA) cerr << " Int Regr not suggested for method arg\n";
      }
     
    }
    else if( RegType==FPSingleRegType && (argNo*2+1) < NumOfFloatArgRegs) 
      LR->setSuggestedColor( SparcFloatRegOrder::f0 + (argNo * 2 + 1) );
    
 
    else if( RegType == FPDoubleRegType && (argNo*2) < NumOfFloatArgRegs) 
      LR->setSuggestedColor( SparcFloatRegOrder::f0 + (argNo * 2) ); 
    

  }
  
}

//---------------------------------------------------------------------------
// 
//---------------------------------------------------------------------------

void UltraSparcRegInfo::colorMethodArgs(const Method *const Meth, 
					LiveRangeInfo& LRI,
					AddedInstrns *const FirstAI) const {

                                                 // get the argument list
  const Method::ArgumentListType& ArgList = Meth->getArgumentList();           
                                                 // get an iterator to arg list
  Method::ArgumentListType::const_iterator ArgIt = ArgList.begin(); 

  MachineInstr *AdMI;


  // for each argument
  for( unsigned argNo=0; ArgIt != ArgList.end() ; ++ArgIt, ++argNo) {    

    // get the LR of arg
    LiveRange *const LR = LRI.getLiveRangeForValue((const Value *) *ArgIt); 
    assert( LR && "No live range found for method arg");


    unsigned RegType = getRegType( LR );
    unsigned RegClassID = (LR->getRegClass())->getID();


    // find whether this argument is coming in a register (if not, on stack)

    bool isArgInReg = false;
    unsigned UniArgReg = InvalidRegNum;	 // reg that LR MUST be colored with

    if( (RegType== IntRegType && argNo <  NumOfIntArgRegs)) {
      isArgInReg = true;
      UniArgReg = getUnifiedRegNum( RegClassID, SparcIntRegOrder::i0 + argNo );
    }
    else if(RegType == FPSingleRegType && argNo < NumOfFloatArgRegs)  { 
      isArgInReg = true;
      UniArgReg = getUnifiedRegNum( RegClassID, 
				    SparcFloatRegOrder::f0 + argNo*2 + 1 ) ;
    }
    else if(RegType == FPDoubleRegType && argNo < NumOfFloatArgRegs)  { 
      isArgInReg = true;
      UniArgReg = getUnifiedRegNum(RegClassID, SparcFloatRegOrder::f0+argNo*2);
    }

    
    if( LR->hasColor() ) {

      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 have a suggested 
      // color or did not receive the suggested color but LR got a register.
      // Now we have to copy %ix reg (or stack pos of arg) 
      // to the register it was colored with.
      
      // if the arg is coming in UniArgReg register MUST go into
      // the UniLRReg register
      if( isArgInReg ) 
	AdMI = cpReg2RegMI( 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
	int ArgStakOffFromFP = 
	  UltraSparcFrameInfo::FirstIncomingArgOffsetFromFP + 
	  argNo * SizeOfOperandOnStack;

	AdMI = cpMem2RegMI(getFramePointer(), ArgStakOffFromFP, 
			   UniLRReg, RegType );
      }

      FirstAI->InstrnsBefore.push_back( AdMI );   
      
    } // 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 ) {

	MachineInstr *AdIBef = 
	  cpReg2MemMI(UniArgReg, getFramePointer(), 
		      LR->getSpillOffFromFP(), RegType );

	FirstAI->InstrnsBefore.push_back( AdMI );   
      }

      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 poistion 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)

	int ArgStakOffFromFP = 
	  UltraSparcFrameInfo::FirstIncomingArgOffsetFromFP + 
	  argNo * SizeOfOperandOnStack;

	LR->modifySpillOffFromFP( ArgStakOffFromFP );
      }

    }

  }  // 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(const MachineInstr *const CallMI, 
					     LiveRangeInfo& LRI,
					     vector<RegClass *> RCList) const {

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

  suggestReg4CallAddr(CallMI, LRI, RCList);


  // First color the return value of the call instruction. The return value
  // will be in %o0 if the value is an integer type, or in %f0 if the 
  // value is a float type.

  // the return value cannot have a LR in machine instruction since it is
  // only defined by the call instruction

  // if type is not void,  create a new live range and set its 
  // register class and add to LRI


  const Value *RetVal = getCallInstRetVal( CallMI );


  if( RetVal ) {

    assert( (! LRI.getLiveRangeForValue( RetVal ) ) && 
	    "LR for ret Value of call already definded!");


      // create a new LR for the return value

    LiveRange * RetValLR = new LiveRange();  
    RetValLR->add( RetVal );
    unsigned RegClassID = getRegClassIDOfValue( RetVal );
    RetValLR->setRegClass( RCList[RegClassID] );
    LRI.addLRToMap( RetVal, RetValLR);
    
    // now suggest a register depending on the register class of ret arg

    if( RegClassID == IntRegClassID ) 
      RetValLR->setSuggestedColor(SparcIntRegOrder::o0);
    else if (RegClassID == FloatRegClassID ) 
      RetValLR->setSuggestedColor(SparcFloatRegOrder::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 =  getCallInstNumArgs( CallMI );
  
  for(unsigned argNo=0, i=0; i < NumOfCallArgs; ++i, ++argNo ) {

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

    // not possible to have a null LR since all args (even consts)  
    // must be defined before
    if( !LR ) {          
      if( DEBUG_RA) {
	cerr << " ERROR: In call instr, no LR for arg:  " ;
	printValue(CallArg); cerr << endl;
      }
      assert(0 && "NO LR for call arg");  
      // continue;
    }
    
    unsigned RegType = getRegType( LR );

    // if the arg is in int class - allocate a reg for an int arg
    if( RegType == IntRegType ) {

      if( argNo < NumOfIntArgRegs) 
	LR->setSuggestedColor( SparcIntRegOrder::o0 + argNo );

      else if (DEBUG_RA) 
	// Do NOTHING as this will be colored as a normal value.
	cerr << " Regr not suggested for int call arg" << endl;
      
    }
    else if( RegType == FPSingleRegType &&  (argNo*2 +1)< NumOfFloatArgRegs) 
      LR->setSuggestedColor( SparcFloatRegOrder::f0 + (argNo * 2 + 1) );
    
 
    else if( RegType == FPDoubleRegType && (argNo*2) < NumOfFloatArgRegs) 
      LR->setSuggestedColor( SparcFloatRegOrder::f0 + (argNo * 2) ); 
    

  } // for all call arguments

}


//---------------------------------------------------------------------------
// 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(const MachineInstr *const CallMI,
				      LiveRangeInfo& LRI,
				      AddedInstrns *const CallAI,
				      PhyRegAlloc &PRA) const {

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

  // 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 = getCallInstRetVal( CallMI );

  if( RetVal ) {

    LiveRange * RetValLR = LRI.getLiveRangeForValue( RetVal );

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

    unsigned RegClassID = (RetValLR->getRegClass())->getID();    
    bool recvCorrectColor = false;

    unsigned CorrectCol;                // correct color for ret value
    if(RegClassID == IntRegClassID)
      CorrectCol = SparcIntRegOrder::o0;
    else if(RegClassID == FloatRegClassID)
      CorrectCol = SparcFloatRegOrder::f0;
    else 
      assert( 0 && "Unknown RegClass");


    // if the LR received the correct color, NOTHING to do

    if(  RetValLR->hasColor() )
      if( RetValLR->getColor() == CorrectCol )
	recvCorrectColor = true;


    // if we didn't receive the correct color for some reason, 
    // put copy instruction
    
    if( !recvCorrectColor ) {

      unsigned RegType = getRegType( RetValLR );

      // the  reg that LR must be colored with 
      unsigned UniRetReg = getUnifiedRegNum( RegClassID, CorrectCol);	
      
      if( RetValLR->hasColor() ) {
	
	unsigned 
	  UniRetLRReg=getUnifiedRegNum(RegClassID,RetValLR->getColor());
	
	// the return value is coming in UniRetReg but has to go into
	// the UniRetLRReg

	AdMI = cpReg2RegMI( 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
	
	AdMI = 	cpReg2MemMI(UniRetReg, getFramePointer(), 
			    RetValLR->getSpillOffFromFP(), RegType );
      }

      CallAI->InstrnsAfter.push_back( AdMI );
      
    } // the LR didn't receive the suggested color  
    
  } // if there a return value
  

  // Now color all args of the call instruction

  unsigned NumOfCallArgs =  getCallInstNumArgs( CallMI );

  for(unsigned argNo=0, i=0; i < NumOfCallArgs; ++i, ++argNo ) {

    const Value *CallArg = CallMI->getImplicitRef(i);

    // get the LR of call operand (parameter)
    LiveRange *const LR = LRI.getLiveRangeForValue(CallArg); 

    unsigned RegType = getRegType( CallArg );
    unsigned RegClassID =  getRegClassIDOfValue( CallArg);
    
    // find whether this argument is coming in a register (if not, on stack)

    bool isArgInReg = false;
    unsigned UniArgReg = InvalidRegNum;  // reg that LR must be colored with

    if( (RegType== IntRegType && argNo <  NumOfIntArgRegs)) {
      isArgInReg = true;
      UniArgReg = getUnifiedRegNum(RegClassID, SparcIntRegOrder::o0 + argNo );
    }
    else if(RegType == FPSingleRegType && argNo < NumOfFloatArgRegs)  { 
      isArgInReg = true;
      UniArgReg = getUnifiedRegNum(RegClassID, 
				   SparcFloatRegOrder::f0 + (argNo*2 + 1) );
    }
    else if(RegType == FPDoubleRegType && argNo < NumOfFloatArgRegs)  { 
      isArgInReg = true;
      UniArgReg = getUnifiedRegNum(RegClassID, SparcFloatRegOrder::f0+argNo*2);
    }


    // not possible to have a null LR since all args (even consts)  
    // must be defined before
    if( !LR ) {          
      if( DEBUG_RA) {
	cerr << " ERROR: In call instr, no LR for arg:  " ;
	printValue(CallArg); cerr << endl;
      }
      assert(0 && "NO LR for call arg");  
      // continue;
    }


    // if the LR received the suggested color, NOTHING to do


    if( LR->hasColor() ) {


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

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

      // We are here because though the LR is allocated a register, it
      // was not allocated the suggested register. So, we have to copy %ix reg 
      // (or stack pos of arg) to the register it was colored with

      // the LR is colored with UniLRReg but has to go into  UniArgReg
      // to pass it as an argument

      if( isArgInReg ) 
	AdMI = cpReg2RegMI(UniLRReg, UniArgReg, RegType );

      else {
	// Now, we have to pass the arg on stack. Since LR received a register
	// we just have to move that register to the stack position where
	// the argument must be passed

	int ArgStakOffFromSP = 
	  UltraSparcFrameInfo::FirstOutgoingArgOffsetFromSP + 
	  argNo * SizeOfOperandOnStack;

	AdMI = cpReg2MemMI(UniLRReg, getStackPointer(), ArgStakOffFromSP, 
			   RegType );
      }

      CallAI->InstrnsBefore.push_back( AdMI );  // Now add the instruction
    }

    else {                          // LR is not colored (i.e., spilled)      
      
      if( isArgInReg ) {

	// Now the LR did NOT recieve a register but has a stack poistion.
	// Since, the outgoing arg goes in a register we just have to insert
	// a load instruction to load the LR to outgoing register


	AdMI = cpMem2RegMI(getStackPointer(), LR->getSpillOffFromFP(),
			   UniArgReg, RegType );

	CallAI->InstrnsBefore.push_back( AdMI );  // 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.
	
	// Optoimize: Optimize when reverse pointers in MahineInstr are
	// introduced. 
	// call PRA.getUnusedRegAtMI(....) to get an unused reg. Only if this
	// fails, then use the following code. Currently, we cannot call the
	// above method since we cannot find LVSetBefore without the BB 
	
	int TReg = PRA.getRegNotUsedByThisInst( LR->getRegClass(), CallMI );
	int TmpOff = PRA.getStackOffsets().getNewTmpPosOffFromFP();
	int ArgStakOffFromSP = 
	  UltraSparcFrameInfo::FirstOutgoingArgOffsetFromSP + 
	  argNo * SizeOfOperandOnStack;

	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)

	Ad1 = cpReg2MemMI(TReg, getFramePointer(), TmpOff, RegType );
	Ad2 = cpMem2RegMI(getFramePointer(), LR->getSpillOffFromFP(), 
			  TReg, RegType ); 
	Ad3 = cpReg2MemMI(TReg, getStackPointer(), ArgStakOffFromSP, RegType );
	Ad4 = cpMem2RegMI(getFramePointer(), TmpOff, TReg, RegType ); 

	CallAI->InstrnsBefore.push_back( Ad1 );  
	CallAI->InstrnsBefore.push_back( Ad2 );  
	CallAI->InstrnsBefore.push_back( Ad3 );  
	CallAI->InstrnsBefore.push_back( Ad4 );  
      }

    }

  }  // for each parameter in call instruction

}

//---------------------------------------------------------------------------
// 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(const MachineInstr *const RetMI, 
					     LiveRangeInfo& LRI) const {

  assert( (UltraSparcInfo->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);

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

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

    unsigned RegClassID = (LR->getRegClass())->getID();
      
    if( RegClassID == IntRegClassID ) 
      LR->setSuggestedColor(SparcIntRegOrder::i0);
    
    else if ( RegClassID == FloatRegClassID ) 
      LR->setSuggestedColor(SparcFloatRegOrder::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(const  MachineInstr *const RetMI, 
				      LiveRangeInfo& LRI,
				      AddedInstrns *const RetAI) const {

  assert( (UltraSparcInfo->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);

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

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

    unsigned RegClassID =  getRegClassIDOfValue(RetVal);
    unsigned RegType = getRegType( RetVal );


    unsigned CorrectCol;
    if(RegClassID == IntRegClassID)
      CorrectCol = SparcIntRegOrder::i0;
    else if(RegClassID == FloatRegClassID)
      CorrectCol = SparcFloatRegOrder::f0;
    else 
      assert( 0 && "Unknown RegClass");


    // if the LR received the correct color, NOTHING to do

    if(  LR->hasColor() )
      if( LR->getColor() == CorrectCol )
	return;

    unsigned UniRetReg =  getUnifiedRegNum( RegClassID, CorrectCol );

    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

      AdMI = cpReg2RegMI( UniLRReg, UniRetReg, RegType); 
      RetAI->InstrnsBefore.push_back( AdMI );
    }
    else {                              // if the LR is spilled

      AdMI = cpMem2RegMI(getFramePointer(), LR->getSpillOffFromFP(), 
			 UniRetReg, RegType); 
      RetAI->InstrnsBefore.push_back( AdMI );
      cout << "\nCopied the return value from stack";
    }
  
  } // if there is a return value

}


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


MachineInstr * UltraSparcRegInfo::cpReg2RegMI(const unsigned SrcReg, 
					      const unsigned DestReg,
					      const int RegType) const {

  assert( ((int)SrcReg != InvalidRegNum) && ((int)DestReg != InvalidRegNum) &&
	  "Invalid Register");
  
  MachineInstr * MI = NULL;

  switch( RegType ) {
    
  case IntRegType:
  case IntCCRegType:
  case FloatCCRegType: 
    MI = new MachineInstr(ADD, 3);
    MI->SetMachineOperand(0, SrcReg, false);
    MI->SetMachineOperand(1, SparcIntRegOrder::g0, false);
    MI->SetMachineOperand(2, DestReg, true);
    break;

  case FPSingleRegType:
    MI = new MachineInstr(FMOVS, 2);
    MI->SetMachineOperand(0, SrcReg, false);
    MI->SetMachineOperand(1, DestReg, true);
    break;

  case FPDoubleRegType:
    MI = new MachineInstr(FMOVD, 2);
    MI->SetMachineOperand(0, SrcReg, false);    
    MI->SetMachineOperand(1, DestReg, true);
    break;

  default:
    assert(0 && "Unknow RegType");
  }

  return MI;
}


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


MachineInstr * UltraSparcRegInfo::cpReg2MemMI(const unsigned SrcReg, 
					      const unsigned DestPtrReg,
					      const int Offset,
					      const int RegType) const {


  MachineInstr * MI = NULL;

  switch( RegType ) {
    
  case IntRegType:
  case IntCCRegType:
  case FloatCCRegType: 
    MI = new MachineInstr(STX, 3);
    MI->SetMachineOperand(0, SrcReg, false);
    MI->SetMachineOperand(1, DestPtrReg, false);
    MI->SetMachineOperand(2, MachineOperand:: MO_SignExtendedImmed, 
			  (int64_t) Offset, false);
    break;

  case FPSingleRegType:
    MI = new MachineInstr(ST, 3);
    MI->SetMachineOperand(0, SrcReg, false);
    MI->SetMachineOperand(1, DestPtrReg, false);
    MI->SetMachineOperand(2, MachineOperand:: MO_SignExtendedImmed, 
			  (int64_t) Offset, false);
    break;

  case FPDoubleRegType:
    MI = new MachineInstr(STD, 3);
    MI->SetMachineOperand(0, SrcReg, false);
    MI->SetMachineOperand(1, DestPtrReg, false);
    MI->SetMachineOperand(2, MachineOperand:: MO_SignExtendedImmed, 
			  (int64_t) Offset, false);
    break;

  default:
    assert(0 && "Unknow RegType");
  }

  return MI;
}


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


MachineInstr * UltraSparcRegInfo::cpMem2RegMI(const unsigned SrcPtrReg,	
					      const int Offset,
					      const unsigned DestReg,
					      const int RegType) const {
  
  MachineInstr * MI = NULL;

  switch( RegType ) {
    
  case IntRegType:
  case IntCCRegType:
  case FloatCCRegType: 
    MI = new MachineInstr(LDX, 3);
    MI->SetMachineOperand(0, SrcPtrReg, false);
    MI->SetMachineOperand(1, MachineOperand:: MO_SignExtendedImmed, 
			  (int64_t) Offset, false);
    MI->SetMachineOperand(2, DestReg, false);
    break;

  case FPSingleRegType:
    MI = new MachineInstr(LD, 3);
    MI->SetMachineOperand(0, SrcPtrReg, false);
    MI->SetMachineOperand(1, MachineOperand:: MO_SignExtendedImmed, 
			  (int64_t) Offset, false);
    MI->SetMachineOperand(2, DestReg, false);

    break;

  case FPDoubleRegType:
    MI = new MachineInstr(LDD, 3);
    MI->SetMachineOperand(0, SrcPtrReg, false);
    MI->SetMachineOperand(1, MachineOperand:: MO_SignExtendedImmed, 
			  (int64_t) Offset, false);
    MI->SetMachineOperand(2, DestReg, false);
    break;

  default:
    assert(0 && "Unknow RegType");
  }

  return MI;
}


MachineInstr* UltraSparcRegInfo::cpValue2Value(Value *Src, Value *Dest) const {

  MachineInstr * MI = NULL;

  MI = new MachineInstr(ADD, 3);
  MI->SetMachineOperand(0, MachineOperand:: MO_VirtualRegister, Src, false);
  MI->SetMachineOperand(1, SparcIntRegOrder::g0, false);
  MI->SetMachineOperand(2, MachineOperand:: MO_VirtualRegister, Dest, true);
  

  return MI;

}



//----------------------------------------------------------------------------
// This method inserts caller saving/restoring instructons before/after
// a call machine instruction.
//----------------------------------------------------------------------------


void UltraSparcRegInfo::insertCallerSavingCode(const MachineInstr *MInst, 
					       const BasicBlock *BB,
					       PhyRegAlloc &PRA) const {
  // assert( (getInstrInfo()).isCall( MInst->getOpCode() ) );

 
  PRA.StackOffsets.resetTmpPos();

  hash_set<unsigned> PushedRegSet;

  // 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 = getCallInstRetVal( MInst );

  if( RetVal ) {

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

    PushedRegSet.insert(
			getUnifiedRegNum((RetValLR->getRegClass())->getID(), 
				      RetValLR->getColor() ) );
  }


  const LiveVarSet *LVSetAft =  PRA.LVI->getLiveVarSetAfterMInst(MInst, BB);

  LiveVarSet::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->getRegClass())->getID();
	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.StackOffsets. getNewTmpPosOffFromFP();

	    /**** TODO  - Handle IntCCRegType
		  


	    }
	    */
	    
	    MachineInstr *AdIBef = 
	      cpReg2MemMI(Reg, getStackPointer(), StackOff, RegType ); 

	    MachineInstr *AdIAft = 
	      cpMem2RegMI(getStackPointer(), StackOff, Reg, RegType ); 

	    ((PRA.AddedInstrMap[MInst])->InstrnsBefore).push_front(AdIBef);
	    ((PRA.AddedInstrMap[MInst])->InstrnsAfter).push_back(AdIAft);
	    
	    PushedRegSet.insert( Reg );

	    if(DEBUG_RA) {
	      cerr << "\nFor callee save call inst:" << *MInst;
	      cerr << "\n  -inserted caller saving instrs:\n\t ";
	      cerr << *AdIBef << "\n\t" << *AdIAft  ;
	    }	    
	  } // 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 *const LR) {

  unsigned RegClassID = (LR->getRegClass())->getID();

  cerr << " *Node " << (LR->getUserIGNode())->getIndex();

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

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

  if( RegClassID == IntRegClassID ) {

    cerr<< " [" << SparcIntRegOrder::getRegName(LR->getColor()) ;
    cerr << "]" << endl;
  }
  else if ( RegClassID == FloatRegClassID) {
    cerr << "[" << SparcFloatRegOrder::getRegName(LR->getColor());
    if( LR->getTypeID() == Type::DoubleTyID )
      cerr << "+" << SparcFloatRegOrder::getRegName(LR->getColor()+1);
    cerr << "]" << endl;
  }
}