1 //===-- RegClass.cpp -----------------------------------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // class RegClass for coloring-based register allocation for LLVM.
12 //===----------------------------------------------------------------------===//
15 #include "RegAllocCommon.h"
17 #include "llvm/Target/TargetRegInfo.h"
19 //----------------------------------------------------------------------------
20 // This constructor inits IG. The actual matrix is created by a call to
21 // createInterferenceGraph() above.
22 //----------------------------------------------------------------------------
23 RegClass::RegClass(const Function *M,
24 const TargetRegInfo *_MRI_,
25 const TargetRegClassInfo *_MRC_)
26 : Meth(M), MRI(_MRI_), MRC(_MRC_),
27 RegClassID( _MRC_->getRegClassID() ),
28 IG(this), IGNodeStack() {
29 if( DEBUG_RA >= RA_DEBUG_Interference)
30 std::cerr << "Created Reg Class: " << RegClassID << "\n";
32 IsColorUsedArr.resize(MRC->getNumOfAllRegs());
37 //----------------------------------------------------------------------------
38 // Main entry point for coloring a register class.
39 //----------------------------------------------------------------------------
40 void RegClass::colorAllRegs()
42 if(DEBUG_RA >= RA_DEBUG_Coloring)
43 std::cerr << "Coloring IG of reg class " << RegClassID << " ...\n";
46 pushAllIGNodes(); // push all IG Nodes
48 unsigned int StackSize = IGNodeStack.size();
51 // for all LRs on stack
52 for( unsigned int IGN=0; IGN < StackSize; IGN++) {
54 CurIGNode = IGNodeStack.top(); // pop the IGNode on top of stack
56 colorIGNode (CurIGNode); // color it
63 //----------------------------------------------------------------------------
64 // The method for pushing all IGNodes on to the stack.
65 //----------------------------------------------------------------------------
66 void RegClass::pushAllIGNodes()
71 IG.setCurDegreeOfIGNodes(); // calculate degree of IGNodes
73 // push non-constrained IGNodes
74 bool PushedAll = pushUnconstrainedIGNodes();
76 if( DEBUG_RA >= RA_DEBUG_Coloring) {
77 std::cerr << " Puhsed all-unconstrained IGNodes. ";
78 if( PushedAll ) std::cerr << " No constrained nodes left.";
82 if( PushedAll ) // if NO constrained nodes left
86 // now, we have constrained nodes. So, push one of them (the one with min
87 // spill cost) and try to push the others as unConstrained nodes.
91 //get node with min spill cost
93 IGNode *IGNodeSpill = getIGNodeWithMinSpillCost();
95 // push that node on to stack
97 IGNodeStack.push(IGNodeSpill);
99 // set its OnStack flag and decrement degree of neighs
101 IGNodeSpill->pushOnStack();
103 // now push NON-constrained ones, if any
105 NeedMoreSpills = !pushUnconstrainedIGNodes();
107 if (DEBUG_RA >= RA_DEBUG_Coloring)
108 std::cerr << "\nConstrained IG Node found !@!" << IGNodeSpill->getIndex();
110 } while(NeedMoreSpills); // repeat until we have pushed all
117 //--------------------------------------------------------------------------
118 // This method goes thru all IG nodes in the IGNodeList of an IG of a
119 // register class and push any unconstrained IG node left (that is not
121 //--------------------------------------------------------------------------
123 bool RegClass::pushUnconstrainedIGNodes()
125 // # of LRs for this reg class
126 unsigned int IGNodeListSize = IG.getIGNodeList().size();
127 bool pushedall = true;
129 // a pass over IGNodeList
130 for( unsigned i =0; i < IGNodeListSize; i++) {
132 // get IGNode i from IGNodeList
133 IGNode *IGNode = IG.getIGNodeList()[i];
135 if( !IGNode ) // can be null due to merging
138 // if already pushed on stack, continue. This can happen since this
139 // method can be called repeatedly until all constrained nodes are
141 if( IGNode->isOnStack() )
143 // if the degree of IGNode is lower
144 if( (unsigned) IGNode->getCurDegree() < MRC->getNumOfAvailRegs()) {
145 IGNodeStack.push( IGNode ); // push IGNode on to the stack
146 IGNode->pushOnStack(); // set OnStack and dec deg of neighs
148 if (DEBUG_RA >= RA_DEBUG_Coloring) {
149 std::cerr << " pushed un-constrained IGNode " << IGNode->getIndex()
153 else pushedall = false; // we didn't push all live ranges
157 // returns true if we pushed all live ranges - else false
163 //----------------------------------------------------------------------------
164 // Get the IGNode with the minimum spill cost
165 //----------------------------------------------------------------------------
166 IGNode * RegClass::getIGNodeWithMinSpillCost()
169 unsigned int IGNodeListSize = IG.getIGNodeList().size();
170 double MinSpillCost = 0;
171 IGNode *MinCostIGNode = NULL;
172 bool isFirstNode = true;
174 // pass over IGNodeList to find the IGNode with minimum spill cost
175 // among all IGNodes that are not yet pushed on to the stack
177 for( unsigned int i =0; i < IGNodeListSize; i++) {
178 IGNode *IGNode = IG.getIGNodeList()[i];
180 if( ! IGNode ) // can be null due to merging
183 if( ! IGNode->isOnStack() ) {
185 double SpillCost = (double) IGNode->getParentLR()->getSpillCost() /
186 (double) (IGNode->getCurDegree() + 1);
188 if( isFirstNode ) { // for the first IG node
189 MinSpillCost = SpillCost;
190 MinCostIGNode = IGNode;
194 else if( MinSpillCost > SpillCost) {
195 MinSpillCost = SpillCost;
196 MinCostIGNode = IGNode;
202 assert( MinCostIGNode && "No IGNode to spill");
203 return MinCostIGNode;
208 //----------------------------------------------------------------------------
209 // Color the IGNode using the machine specific code.
210 //----------------------------------------------------------------------------
211 void RegClass::colorIGNode(IGNode *const Node)
214 if( ! Node->hasColor() ) { // not colored as an arg etc.
216 // init all elements of to IsColorUsedAr false;
219 // initialize all colors used by neighbors of this node to true
220 LiveRange *LR = Node->getParentLR();
221 unsigned NumNeighbors = Node->getNumOfNeighbors();
222 for (unsigned n=0; n < NumNeighbors; n++) {
223 IGNode *NeighIGNode = Node->getAdjIGNode(n);
224 LiveRange *NeighLR = NeighIGNode->getParentLR();
226 // Don't use a color if it is in use by the neighbor,
227 // or is suggested for use by the neighbor,
228 // markColorsUsed() should be given the color and the reg type for
229 // LR, not for NeighLR, because it should mark registers used based on
230 // the type we are looking for, not on the regType for the neighbour.
231 if (NeighLR->hasColor())
232 this->markColorsUsed(NeighLR->getColor(),
233 MRI->getRegTypeForLR(NeighLR),
234 MRI->getRegTypeForLR(LR)); // use LR, not NeighLR
235 else if (NeighLR->hasSuggestedColor() &&
236 NeighLR->isSuggestedColorUsable())
237 this->markColorsUsed(NeighLR->getSuggestedColor(),
238 MRI->getRegTypeForLR(NeighLR),
239 MRI->getRegTypeForLR(LR)); // use LR, not NeighLR
242 // call the target specific code for coloring
244 MRC->colorIGNode(Node, IsColorUsedArr);
247 if( DEBUG_RA >= RA_DEBUG_Coloring) {
248 std::cerr << " Node " << Node->getIndex();
249 std::cerr << " already colored with color " << Node->getColor() << "\n";
254 if( !Node->hasColor() ) {
255 if( DEBUG_RA >= RA_DEBUG_Coloring) {
256 std::cerr << " Node " << Node->getIndex();
257 std::cerr << " - could not find a color (needs spilling)\n";
263 void RegClass::printIGNodeList() const {
264 std::cerr << "IG Nodes for Register Class " << RegClassID << ":" << "\n";
265 IG.printIGNodeList();
268 void RegClass::printIG() {
269 std::cerr << "IG for Register Class " << RegClassID << ":" << "\n";