//===-- RegClass.cpp -----------------------------------------------------===// // // class RegClass for coloring-based register allocation for LLVM. // //===----------------------------------------------------------------------===// #include "RegClass.h" #include "RegAllocCommon.h" #include "llvm/CodeGen/IGNode.h" #include "llvm/Target/TargetRegInfo.h" using std::cerr; //---------------------------------------------------------------------------- // This constructor inits IG. The actual matrix is created by a call to // createInterferenceGraph() above. //---------------------------------------------------------------------------- RegClass::RegClass(const Function *M, const TargetRegInfo *_MRI_, const TargetRegClassInfo *_MRC_) : Meth(M), MRI(_MRI_), MRC(_MRC_), RegClassID( _MRC_->getRegClassID() ), IG(this), IGNodeStack() { if( DEBUG_RA >= RA_DEBUG_Interference) 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) 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) { cerr << " Puhsed all-unconstrained IGNodes. "; if( PushedAll ) cerr << " No constrained nodes left."; 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-constrined ones, if any // NeedMoreSpills = !pushUnconstrainedIGNodes(); if (DEBUG_RA >= RA_DEBUG_Coloring) 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) { cerr << " pushed un-constrained IGNode " << IGNode->getIndex() ; cerr << " 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 withe 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 neighbour, // or is suggested for use by the neighbour, // 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) { cerr << " Node " << Node->getIndex(); cerr << " already colored with color " << Node->getColor() << "\n"; } } if( !Node->hasColor() ) { if( DEBUG_RA >= RA_DEBUG_Coloring) { cerr << " Node " << Node->getIndex(); 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(); }