001 /*
002 * This file is part of the Jikes RVM project (http://jikesrvm.org).
003 *
004 * This file is licensed to You under the Eclipse Public License (EPL);
005 * You may not use this file except in compliance with the License. You
006 * may obtain a copy of the License at
007 *
008 * http://www.opensource.org/licenses/eclipse-1.0.php
009 *
010 * See the COPYRIGHT.txt file distributed with this work for information
011 * regarding copyright ownership.
012 */
013 package org.jikesrvm.compilers.opt.regalloc;
014
015 import java.util.Enumeration;
016 import org.jikesrvm.compilers.opt.ir.BasicBlock;
017 import org.jikesrvm.compilers.opt.ir.IR;
018 import org.jikesrvm.compilers.opt.ir.Instruction;
019 import org.jikesrvm.compilers.opt.ir.Register;
020 import org.jikesrvm.compilers.opt.ir.operand.MemoryOperand;
021 import org.jikesrvm.compilers.opt.ir.operand.Operand;
022
023 /**
024 * An object that returns an estimate of the relative cost of spilling a
025 * symbolic register.
026 */
027 class SimpleSpillCost extends SpillCostEstimator {
028
029 SimpleSpillCost(IR ir) {
030 calculate(ir);
031 }
032
033 @Override
034 void calculate(IR ir) {
035 final double moveFactor = ir.options.REGALLOC_SIMPLE_SPILL_COST_MOVE_FACTOR;
036 final double memoryOperandFactor = ir.options.REGALLOC_SIMPLE_SPILL_COST_MEMORY_OPERAND_FACTOR;
037 for (Enumeration<BasicBlock> e = ir.getBasicBlocks(); e.hasMoreElements();) {
038 BasicBlock bb = e.nextElement();
039 for (Enumeration<Instruction> ie = bb.forwardInstrEnumerator(); ie.hasMoreElements();) {
040 Instruction s = ie.nextElement();
041 double factor = (bb.getInfrequent()) ? 0.0 : 1.0;
042 if (s.isMove()) {
043 factor *= moveFactor;
044 }
045 double baseFactor = factor;
046 if (hasBadSizeMemoryOperand(s)) {
047 baseFactor *= memoryOperandFactor;
048 }
049 // first deal with non-memory operands
050 for (Enumeration<Operand> e2 = s.getRootOperands(); e2.hasMoreElements();) {
051 Operand op = e2.nextElement();
052 if (op.isRegister()) {
053 Register r = op.asRegister().getRegister();
054 if (r.isSymbolic()) {
055 update(r, baseFactor);
056 }
057 }
058 }
059 // now handle memory operands
060 factor *= memoryOperandFactor;
061 for (Enumeration<Operand> e2 = s.getMemoryOperands(); e2.hasMoreElements();) {
062 MemoryOperand M = (MemoryOperand) e2.nextElement();
063 if (M.base != null) {
064 Register r = M.base.getRegister();
065 if (r.isSymbolic()) {
066 update(r, factor);
067 }
068 }
069 if (M.index != null) {
070 Register r = M.index.getRegister();
071 if (r.isSymbolic()) {
072 update(r, factor);
073 }
074 }
075 }
076 }
077 }
078 }
079
080 /**
081 * Does instruction s have a memory operand of an inconvenient size?<p>
082 *
083 * NOTE: This is pretty intel-specific.
084 * TODO Refactor to arch/ tree.
085 */
086 static boolean hasBadSizeMemoryOperand(Instruction s) {
087 for (Enumeration<Operand> e = s.getMemoryOperands(); e.hasMoreElements();) {
088 MemoryOperand M = (MemoryOperand) e.nextElement();
089 if (M.size != 4) return true;
090 }
091 return false;
092 }
093 }