llvm/lib/Target/SparcV9/SparcV9RegClassInfo.cpp

//===-- SparcV9RegClassInfo.cpp - Register class def'ns for SparcV9 -------===//
// 
//                     The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
// 
//===----------------------------------------------------------------------===//
//
// This file defines the methods used by the SparcV9 register allocator
// to pick registers of various classes.  Most of this code should be
// considered part of the register allocator.
//
//===----------------------------------------------------------------------===//

#include "llvm/Type.h"
#include "SparcV9RegClassInfo.h"
#include "SparcV9Internals.h"
#include "SparcV9RegInfo.h"
#include "RegAlloc/RegAllocCommon.h"
#include "RegAlloc/IGNode.h"
#include <iostream>

namespace llvm {

//-----------------------------------------------------------------------------
// Int Register Class - method for coloring a node in the interference graph.
//
// Algorithm:
//     Record the colors/suggested colors of all neighbors.
//
//     If there is a suggested color, try to allocate it
//     If there is no call interf, try to allocate volatile, then non volatile
//     If there is call interf, try to allocate non-volatile. If that fails
//     try to allocate a volatile and insert save across calls
//     If both above fail, spill.
//  
//-----------------------------------------------------------------------------
void SparcV9IntRegClass::colorIGNode(IGNode * Node,
                               const std::vector<bool> &IsColorUsedArr) const
{
  LiveRange *LR = Node->getParentLR();

  if (DEBUG_RA) {
    std::cerr << "\nColoring LR [CallInt=" << LR->isCallInterference() <<"]:"; 
    printSet(*LR);
  }

  if (LR->hasSuggestedColor()) {
    unsigned SugCol = LR->getSuggestedColor();
    if (!IsColorUsedArr[SugCol]) {
      if (LR->isSuggestedColorUsable()) {
	// if the suggested color is volatile, we should use it only if
	// there are no call interferences. Otherwise, it will get spilled.
	if (DEBUG_RA)
	  std::cerr << "\n  -Coloring with sug color: " << SugCol;

	LR->setColor(LR->getSuggestedColor());
	return;
      } else if(DEBUG_RA) {
        std::cerr << "\n Couldn't alloc Sug col - LR volatile & calls interf";
      }
    } else if (DEBUG_RA) {                // can't allocate the suggested col
      std::cerr << "\n  Could NOT allocate the suggested color (already used) ";
      printSet(*LR); std::cerr << "\n";
    }
  }

  unsigned SearchStart;                 // start pos of color in pref-order
  bool ColorFound= false;               // have we found a color yet?

  //if this Node is between calls
  if (! LR->isCallInterference()) { 
    // start with volatiles (we can  allocate volatiles safely)
    SearchStart = SparcV9IntRegClass::StartOfAllRegs;  
  } else {           
    // start with non volatiles (no non-volatiles)
    SearchStart =  SparcV9IntRegClass::StartOfNonVolatileRegs;  
  }

  unsigned c=0;                         // color
 
  // find first unused color
  for (c=SearchStart; c < SparcV9IntRegClass::NumOfAvailRegs; c++) { 
    if (!IsColorUsedArr[c]) {
      ColorFound = true;
      break;
    }
  }

  if (ColorFound) {
    LR->setColor(c);                  // first color found in preferred order
    if (DEBUG_RA) std::cerr << "\n  Colored after first search with col " << c;
  }

  // if color is not found because of call interference
  // try even finding a volatile color and insert save across calls
  //
  else if (LR->isCallInterference()) {
    // start from 0 - try to find even a volatile this time
    SearchStart = SparcV9IntRegClass::StartOfAllRegs;  

    // find first unused volatile color
    for(c=SearchStart; c < SparcV9IntRegClass::StartOfNonVolatileRegs; c++) { 
      if (! IsColorUsedArr[c]) {
        ColorFound = true;
        break;
      }
    }

    if (ColorFound) { 
      LR->setColor(c);  
      //  get the live range corresponding to live var
      // since LR span across calls, must save across calls 
      //
      LR->markForSaveAcrossCalls();       
      if (DEBUG_RA)
        std::cerr << "\n  Colored after SECOND search with col " << c;
    }
  }


  // If we couldn't find a color regardless of call interference - i.e., we
  // don't have either a volatile or non-volatile color left
  //
  if (!ColorFound)  
    LR->markForSpill();               // no color found - must spill
}

//-----------------------------------------------------------------------------
// Int CC Register Class - method for coloring a node in the interference graph.
//
// Algorithm:
//
//     If (node has any interferences)
//         /* all interference operations can use only one register! */
//         mark the LR for spilling
//     else {
//         if (the LR is a 64-bit comparison) use %xcc
//         else /*32-bit or smaller*/ use %icc
//     }
// 
// Note: The third name (%ccr) is essentially an assembly mnemonic and
// depends solely on the opcode, so the name can be chosen in EmitAssembly.
//-----------------------------------------------------------------------------
void SparcV9IntCCRegClass::colorIGNode(IGNode *Node,
                                 const std::vector<bool> &IsColorUsedArr) const
{
  if (Node->getNumOfNeighbors() > 0)
    Node->getParentLR()->markForSpill();

  // Mark the appropriate register in any case (even if it needs to be spilled)
  // because there is only one possible register, but more importantly, the
  // spill algorithm cannot find it.  In particular, we have to choose
  // whether to use %xcc or %icc based on type of value compared
  // 
  const LiveRange* ccLR = Node->getParentLR();
  const Type* setCCType = (* ccLR->begin())->getType(); // any Value in LR
  assert(setCCType->isIntegral() || isa<PointerType>(setCCType));
  int ccReg = ((isa<PointerType>(setCCType) || setCCType == Type::LongTy)
               ? xcc : icc);

#ifndef NDEBUG
  // Let's just make sure values of two different types have not been
  // coalesced into this LR.
  for (ValueSet::const_iterator I=ccLR->begin(), E=ccLR->end(); I!=E; ++I) {
    const Type* ccType = (*I)->getType();
    assert((ccReg == xcc && (isa<PointerType>(ccType)
                             || ccType == Type::LongTy)) ||
           (ccReg == icc && ccType->isIntegral() && ccType != Type::LongTy)
           && "Comparisons needing different intCC regs coalesced in LR!");
  }
#endif

  Node->setColor(ccReg);                // only one int cc reg is available
}


void SparcV9FloatCCRegClass::colorIGNode(IGNode *Node,
                                const std::vector<bool> &IsColorUsedArr) const {
  for(unsigned c = 0; c != 4; ++c)
    if (!IsColorUsedArr[c]) { // find unused color
      Node->setColor(c);   
      return;
    }
  
  Node->getParentLR()->markForSpill();
}



//-----------------------------------------------------------------------------
// Float Register Class - method for coloring a node in the interference graph.
//
// Algorithm:
//
//     If the LR is a double try to allocate f32 - f63
//     If the above fails or LR is single precision
//        If the LR does not interfere with a call
//	   start allocating from f0
//	Else start allocating from f6
//     If a color is still not found because LR interferes with a call
//        Search in f0 - f6. If found mark for spill across calls.
//     If a color is still not fond, mark for spilling
//
//----------------------------------------------------------------------------
void SparcV9FloatRegClass::colorIGNode(IGNode * Node,
                                 const std::vector<bool> &IsColorUsedArr) const
{
  LiveRange *LR = Node->getParentLR();

#ifndef NDEBUG
  // Check that the correct colors have been are marked for fp-doubles.
  // 
  // FIXME: This is old code that is no longer needed.  Temporarily converting
  // it into a big assertion just to check that the replacement logic
  // (invoking SparcV9FloatRegClass::markColorsUsed() directly from
  // RegClass::colorIGNode) works correctly.
  // 
  // In fact, this entire function should be identical to
  // SparcV9IntRegClass::colorIGNode(), and perhaps can be
  // made into a general case in CodeGen/RegAlloc/RegClass.cpp.  
  // 
  unsigned NumNeighbors =  Node->getNumOfNeighbors();   // total # of neighbors
  for(unsigned n=0; n < NumNeighbors; n++) {            // for each neigh 
    IGNode *NeighIGNode = Node->getAdjIGNode(n);
    LiveRange *NeighLR = NeighIGNode->getParentLR();
    
    if (NeighLR->hasColor()) {
      assert(IsColorUsedArr[ NeighLR->getColor() ]);
      if (NeighLR->getType() == Type::DoubleTy)
        assert(IsColorUsedArr[ NeighLR->getColor()+1 ]);
      
    } else if (NeighLR->hasSuggestedColor() &&
               NeighLR-> isSuggestedColorUsable() ) {

      // if the neighbour can use the suggested color 
      assert(IsColorUsedArr[ NeighLR->getSuggestedColor() ]);
      if (NeighLR->getType() == Type::DoubleTy)
        assert(IsColorUsedArr[ NeighLR->getSuggestedColor()+1 ]);
    }
  }
#endif

  // **NOTE: We don't check for call interferences in allocating suggested
  // color in this class since ALL registers are volatile. If this fact
  // changes, we should change the following part 
  //- see SparcV9IntRegClass::colorIGNode()
  // 
  if( LR->hasSuggestedColor() ) {
    if( ! IsColorUsedArr[ LR->getSuggestedColor() ] ) {
      LR->setColor(  LR->getSuggestedColor() );
      return;
    } else if (DEBUG_RA)  {                 // can't allocate the suggested col
      std::cerr << " Could NOT allocate the suggested color for LR ";
      printSet(*LR); std::cerr << "\n";
    }
  }


  int ColorFound = -1;               // have we found a color yet?
  bool isCallInterf = LR->isCallInterference();

  // if value is a double - search the double only region (f32 - f63)
  // i.e. we try to allocate f32 - f63 first for doubles since singles
  // cannot go there. By doing that, we provide more space for singles
  // in f0 - f31
  //
  if (LR->getType() == Type::DoubleTy)       
    ColorFound = findFloatColor( LR, 32, 64, IsColorUsedArr );

  if (ColorFound >= 0) {               // if we could find a color
    LR->setColor(ColorFound);                
    return;
  } else { 

    // if we didn't find a color because the LR was single precision or
    // all f32-f63 range is filled, we try to allocate a register from
    // the f0 - f31 region 

    unsigned SearchStart;                 // start pos of color in pref-order

    //if this Node is between calls (i.e., no call interferences )
    if (! isCallInterf) {
      // start with volatiles (we can  allocate volatiles safely)
      SearchStart = SparcV9FloatRegClass::StartOfAllRegs;  
    } else {
      // start with non volatiles (no non-volatiles)
      SearchStart =  SparcV9FloatRegClass::StartOfNonVolatileRegs;  
    }
    
    ColorFound = findFloatColor(LR, SearchStart, 32, IsColorUsedArr);
  }

  if (ColorFound >= 0) {               // if we could find a color
    LR->setColor(ColorFound);                  
    return;
  } else if (isCallInterf) { 
    // We are here because there is a call interference and no non-volatile
    // color could be found.
    // Now try to allocate even a volatile color
    ColorFound = findFloatColor(LR, SparcV9FloatRegClass::StartOfAllRegs, 
				SparcV9FloatRegClass::StartOfNonVolatileRegs,
				IsColorUsedArr);
  }

  if (ColorFound >= 0) {
    LR->setColor(ColorFound);         // first color found in preferred order
    LR->markForSaveAcrossCalls();  
  } else {
    // we are here because no color could be found
    LR->markForSpill();               // no color found - must spill
  }
}

//-----------------------------------------------------------------------------
// This method marks the registers used for a given register number.
// This marks a single register for Float regs, but the R,R+1 pair
// for double-precision registers.
//-----------------------------------------------------------------------------

void SparcV9FloatRegClass::markColorsUsed(unsigned RegInClass,
                                        int UserRegType,
                                        int RegTypeWanted,
                                    std::vector<bool> &IsColorUsedArr) const
{
  if (UserRegType == SparcV9RegInfo::FPDoubleRegType ||
      RegTypeWanted == SparcV9RegInfo::FPDoubleRegType) {
    // This register is used as or is needed as a double-precision reg.
    // We need to mark the [even,odd] pair corresponding to this reg.
    // Get the even numbered register corresponding to this reg.
    unsigned EvenRegInClass = RegInClass & ~1u;
    assert(EvenRegInClass+1 < NumOfAllRegs &&
           EvenRegInClass+1 < IsColorUsedArr.size());
    IsColorUsedArr[EvenRegInClass]   = true;
    IsColorUsedArr[EvenRegInClass+1] = true;
  }
  else {
    assert(RegInClass < NumOfAllRegs && RegInClass < IsColorUsedArr.size());
    assert(UserRegType == RegTypeWanted
           && "Something other than FP single/double types share a reg class?");
    IsColorUsedArr[RegInClass] = true;
  }
}

// This method finds unused registers of the specified register type,
// using the given "used" flag array IsColorUsedArr.  It checks a single
// entry in the array directly for float regs, and checks the pair [R,R+1]
// for double-precision registers
// It returns -1 if no unused color is found.
// 
int SparcV9FloatRegClass::findUnusedColor(int RegTypeWanted,
                                const std::vector<bool> &IsColorUsedArr) const
{
  if (RegTypeWanted == SparcV9RegInfo::FPDoubleRegType) {
    unsigned NC = 2 * this->getNumOfAvailRegs();
    assert(IsColorUsedArr.size() == NC && "Invalid colors-used array");
    for (unsigned c = 0; c < NC; c+=2)
      if (!IsColorUsedArr[c]) {
        assert(!IsColorUsedArr[c+1] && "Incorrect used regs for FP double!");
	return c;
      }
    return -1;
  }
  else
    return TargetRegClassInfo::findUnusedColor(RegTypeWanted, IsColorUsedArr);
}

//-----------------------------------------------------------------------------
// Helper method for coloring a node of Float Reg class.
// Finds the first available color in the range [Start,End] depending on the
// type of the Node (i.e., float/double)
//-----------------------------------------------------------------------------

int SparcV9FloatRegClass::findFloatColor(const LiveRange *LR, 
                                       unsigned Start,
                                       unsigned End, 
                               const std::vector<bool> &IsColorUsedArr) const
{
  if (LR->getType() == Type::DoubleTy) { 
    // find first unused color for a double 
    assert(Start % 2 == 0 && "Odd register number could be used for double!");
    for (unsigned c=Start; c < End ; c+= 2)
      if (!IsColorUsedArr[c]) {
        assert(!IsColorUsedArr[c+1] &&
               "Incorrect marking of used regs for SparcV9 FP double!");
	return c;
      }
  } else {
    // find first unused color for a single
    for (unsigned c = Start; c < End; c++)
      if (!IsColorUsedArr[c])
        return c;
  }

  return -1;

}

} // End llvm namespace