lib/CodeGen/RegAlloc/LiveRange.h

/* Title:   LiveRange.h
   Author:  Ruchira Sasanka
   Date:    July 25, 01
   Purpose: To keep info about a live range. 
   Asuumptions:

   Since the Value pointed by a use is the same as of its def, it is sufficient
   to keep only defs in a LiveRange.
*/

#ifndef LIVE_RANGE_H
#define LIVE_RANGE_H

#include "llvm/Analysis/LiveVar/ValueSet.h"
#include "llvm/Type.h"




class RegClass;
class IGNode;


class LiveRange : public ValueSet
{
 private:

  RegClass *MyRegClass;       // register classs (e.g., int, FP) for this LR

  // a list of call instructions that interferes with this live range
  //vector<const Instruction *> CallInterferenceList;  

  // does this live range span across calls? 
  // This information is used by graph
  // coloring algo to avoid allocating volatile colors to live ranges
  // that span across calls (since they have to be saved/restored)

  bool doesSpanAcrossCalls;

  IGNode *UserIGNode;         // IGNode which uses this LR
  int Color;                  // color assigned to this live range
  bool mustSpill;             // whether this LR must be spilt

  // whether this LR must be saved accross calls ***TODO REMOVE this
  bool mustSaveAcrossCalls;        

  // bool mustLoadFromStack;     // must load from stack at start of method


  int SuggestedColor;        // The suggested color for this LR

  // if this LR has a suggested color, can it be really alloated?
  // A suggested color cannot be allocated when the suggested color is
  // volatile and when there are call interferences.

  bool CanUseSuggestedCol;

  // if this LR is spilled, its stack offset from *FP*. The spilled offsets
  // must always be relative to the FP.
  int SpilledStackOffsetFromFP;
  bool HasSpillOffset;

 public:


  ~LiveRange() {}             // empty destructor 

  void setRegClass(RegClass *const RC) 
    { MyRegClass = RC; }

  inline RegClass *const getRegClass() const 
    { assert(MyRegClass); return MyRegClass; } 

  inline bool hasColor() const 
    { return Color != -1; }
  
  inline unsigned int getColor() const 
    { assert( Color != -1); return (unsigned) Color ; }

  inline void setColor(unsigned int Col) 
    { Color = (int) Col ; }

  
  inline void setCallInterference() { 
    doesSpanAcrossCalls = 1;
  }


  inline bool isCallInterference() const { 
    return (doesSpanAcrossCalls == 1); 
  } 

  
  inline void markForSpill() { mustSpill = true; }

  inline bool isMarkedForSpill() { return  mustSpill; }

  inline void setSpillOffFromFP(int StackOffset) {
    assert( mustSpill && "This LR is not spilled");
    SpilledStackOffsetFromFP = StackOffset;
    HasSpillOffset = true;
  }

  inline void modifySpillOffFromFP(int StackOffset) {
    assert( mustSpill && "This LR is not spilled");
    SpilledStackOffsetFromFP = StackOffset;
    HasSpillOffset = true;
  }



  inline bool hasSpillOffset() {
    return  HasSpillOffset;
  }


  inline int getSpillOffFromFP() const {
    assert( HasSpillOffset && "This LR is not spilled");
    return SpilledStackOffsetFromFP;
  }


  inline void markForSaveAcrossCalls() { mustSaveAcrossCalls = true; }

  // inline void markForLoadFromStack() { mustLoadFromStack = true; 


  inline void setUserIGNode( IGNode *const IGN) 
    { assert( !UserIGNode); UserIGNode = IGN; }

  inline IGNode * getUserIGNode() const 
    { return UserIGNode; }    // NULL if the user is not allocated

  inline Type::PrimitiveID getTypeID() const {
    const Value *val = *begin();
    assert(val && "Can't find type - Live range is empty" );
    return (val->getType())->getPrimitiveID();
  }


  inline void setSuggestedColor(int Col) {
    //assert( (SuggestedColor == -1) && "Changing an already suggested color");

    if(SuggestedColor == -1 )
      SuggestedColor = Col;
    else if (DEBUG_RA) 
      cerr << "Already has a suggested color " << Col << endl;
  }

  inline unsigned getSuggestedColor() const {
    assert( SuggestedColor != -1);      // only a valid color is obtained
    return (unsigned) SuggestedColor;
  }

  inline bool hasSuggestedColor() const {
    return ( SuggestedColor > -1);
  }

  inline bool isSuggestedColorUsable() const {
    assert( hasSuggestedColor() && "No suggested color");
    return CanUseSuggestedCol;
  }

  inline void setSuggestedColorUsable(const bool val) {
    assert( hasSuggestedColor() && "No suggested color");
    CanUseSuggestedCol = val;
  }







  inline LiveRange() : ValueSet() /* , CallInterferenceList() */
    {
      Color = SuggestedColor = -1;      // not yet colored 
      mustSpill = mustSaveAcrossCalls = false;
      MyRegClass = NULL;
      UserIGNode = NULL;
      doesSpanAcrossCalls = false;
      CanUseSuggestedCol = true;
      HasSpillOffset  = false;
    }

};





#endif