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//===-- RegClass.cpp -----------------------------------------------------===//
//
// 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.
//
//===----------------------------------------------------------------------===//
//
// class RegClass for coloring-based register allocation for LLVM.
//
//===----------------------------------------------------------------------===//
#include "IGNode.h"
#include "RegAllocCommon.h"
#include "RegClass.h"
#include "../SparcV9RegInfo.h"
#include <iostream>
namespace llvm {
//----------------------------------------------------------------------------
// This constructor inits IG. The actual matrix is created by a call to
// createInterferenceGraph() above.
//----------------------------------------------------------------------------
RegClass::RegClass(const Function *M,
const SparcV9RegInfo *_MRI_,
const TargetRegClassInfo *_MRC_)
: Meth(M), MRI(_MRI_), MRC(_MRC_),
RegClassID( _MRC_->getRegClassID() ),
IG(this), IGNodeStack() {
if (DEBUG_RA >= RA_DEBUG_Interference)
std::cerr << "Created Reg Class: " << RegClassID << "\n";
IsColorUsedArr.resize(MRC->getNumOfAllRegs());
}
//----------------------------------------------------------------------------
// Main entry point for coloring a register class.
//----------------------------------------------------------------------------
void RegClass::colorAllRegs()
{
if (DEBUG_RA >= RA_DEBUG_Coloring)
std::cerr << "Coloring IG of reg class " << RegClassID << " ...\n";
// pre-color IGNodes
pushAllIGNodes(); // push all IG Nodes
unsigned int StackSize = IGNodeStack.size();
IGNode *CurIGNode;
// for all LRs on stack
for (unsigned int IGN=0; IGN < StackSize; IGN++) {
CurIGNode = IGNodeStack.top(); // pop the IGNode on top of stack
IGNodeStack.pop();
colorIGNode (CurIGNode); // color it
}
}
//----------------------------------------------------------------------------
// The method for pushing all IGNodes on to the stack.
//----------------------------------------------------------------------------
void RegClass::pushAllIGNodes()
{
bool NeedMoreSpills;
IG.setCurDegreeOfIGNodes(); // calculate degree of IGNodes
// push non-constrained IGNodes
bool PushedAll = pushUnconstrainedIGNodes();
if (DEBUG_RA >= RA_DEBUG_Coloring) {
std::cerr << " Puhsed all-unconstrained IGNodes. ";
if( PushedAll ) std::cerr << " No constrained nodes left.";
std::cerr << "\n";
}
if (PushedAll) // if NO constrained nodes left
return;
// now, we have constrained nodes. So, push one of them (the one with min
// spill cost) and try to push the others as unConstrained nodes.
// Repeat this.
do {
//get node with min spill cost
IGNode *IGNodeSpill = getIGNodeWithMinSpillCost();
// push that node on to stack
IGNodeStack.push(IGNodeSpill);
// set its OnStack flag and decrement degree of neighs
IGNodeSpill->pushOnStack();
// now push NON-constrained ones, if any
NeedMoreSpills = !pushUnconstrainedIGNodes();
if (DEBUG_RA >= RA_DEBUG_Coloring)
std::cerr << "\nConstrained IG Node found !@!" << IGNodeSpill->getIndex();
} while(NeedMoreSpills); // repeat until we have pushed all
}
//--------------------------------------------------------------------------
// This method goes thru all IG nodes in the IGNodeList of an IG of a
// register class and push any unconstrained IG node left (that is not
// already pushed)
//--------------------------------------------------------------------------
bool RegClass::pushUnconstrainedIGNodes()
{
// # of LRs for this reg class
unsigned int IGNodeListSize = IG.getIGNodeList().size();
bool pushedall = true;
// a pass over IGNodeList
for (unsigned i =0; i < IGNodeListSize; i++) {
// get IGNode i from IGNodeList
IGNode *IGNode = IG.getIGNodeList()[i];
if (!IGNode ) // can be null due to merging
continue;
// if already pushed on stack, continue. This can happen since this
// method can be called repeatedly until all constrained nodes are
// pushed
if (IGNode->isOnStack() )
continue;
// if the degree of IGNode is lower
if ((unsigned) IGNode->getCurDegree() < MRC->getNumOfAvailRegs()) {
IGNodeStack.push( IGNode ); // push IGNode on to the stack
IGNode->pushOnStack(); // set OnStack and dec deg of neighs
if (DEBUG_RA >= RA_DEBUG_Coloring) {
std::cerr << " pushed un-constrained IGNode " << IGNode->getIndex()
<< " on to stack\n";
}
}
else pushedall = false; // we didn't push all live ranges
} // for
// returns true if we pushed all live ranges - else false
return pushedall;
}
//----------------------------------------------------------------------------
// Get the IGNode with the minimum spill cost
//----------------------------------------------------------------------------
IGNode * RegClass::getIGNodeWithMinSpillCost() {
unsigned int IGNodeListSize = IG.getIGNodeList().size();
double MinSpillCost = 0;
IGNode *MinCostIGNode = NULL;
bool isFirstNode = true;
// pass over IGNodeList to find the IGNode with minimum spill cost
// among all IGNodes that are not yet pushed on to the stack
for (unsigned int i =0; i < IGNodeListSize; i++) {
IGNode *IGNode = IG.getIGNodeList()[i];
if (!IGNode) // can be null due to merging
continue;
if (!IGNode->isOnStack()) {
double SpillCost = (double) IGNode->getParentLR()->getSpillCost() /
(double) (IGNode->getCurDegree() + 1);
if (isFirstNode) { // for the first IG node
MinSpillCost = SpillCost;
MinCostIGNode = IGNode;
isFirstNode = false;
} else if (MinSpillCost > SpillCost) {
MinSpillCost = SpillCost;
MinCostIGNode = IGNode;
}
}
}
assert (MinCostIGNode && "No IGNode to spill");
return MinCostIGNode;
}
//----------------------------------------------------------------------------
// Color the IGNode using the machine specific code.
//----------------------------------------------------------------------------
void RegClass::colorIGNode(IGNode *const Node) {
if (! Node->hasColor()) { // not colored as an arg etc.
// init all elements of to IsColorUsedAr false;
clearColorsUsed();
// initialize all colors used by neighbors of this node to true
LiveRange *LR = Node->getParentLR();
unsigned NumNeighbors = Node->getNumOfNeighbors();
for (unsigned n=0; n < NumNeighbors; n++) {
IGNode *NeighIGNode = Node->getAdjIGNode(n);
LiveRange *NeighLR = NeighIGNode->getParentLR();
// Don't use a color if it is in use by the neighbor,
// or is suggested for use by the neighbor,
// markColorsUsed() should be given the color and the reg type for
// LR, not for NeighLR, because it should mark registers used based on
// the type we are looking for, not on the regType for the neighbour.
if (NeighLR->hasColor())
this->markColorsUsed(NeighLR->getColor(),
MRI->getRegTypeForLR(NeighLR),
MRI->getRegTypeForLR(LR)); // use LR, not NeighLR
else if (NeighLR->hasSuggestedColor() &&
NeighLR->isSuggestedColorUsable())
this->markColorsUsed(NeighLR->getSuggestedColor(),
MRI->getRegTypeForLR(NeighLR),
MRI->getRegTypeForLR(LR)); // use LR, not NeighLR
}
// call the target specific code for coloring
//
MRC->colorIGNode(Node, IsColorUsedArr);
} else {
if (DEBUG_RA >= RA_DEBUG_Coloring) {
std::cerr << " Node " << Node->getIndex();
std::cerr << " already colored with color " << Node->getColor() << "\n";
}
}
if (!Node->hasColor() ) {
if (DEBUG_RA >= RA_DEBUG_Coloring) {
std::cerr << " Node " << Node->getIndex();
std::cerr << " - could not find a color (needs spilling)\n";
}
}
}
void RegClass::printIGNodeList() const {
std::cerr << "IG Nodes for Register Class " << RegClassID << ":" << "\n";
IG.printIGNodeList();
}
void RegClass::printIG() {
std::cerr << "IG for Register Class " << RegClassID << ":" << "\n";
IG.printIG();
}
} // End llvm namespace
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