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    
017    import org.jikesrvm.compilers.opt.ir.BasicBlock;
018    import org.jikesrvm.compilers.opt.ir.IR;
019    import org.jikesrvm.compilers.opt.ir.Instruction;
020    import org.jikesrvm.compilers.opt.ir.Register;
021    import org.jikesrvm.compilers.opt.ir.operand.MemoryOperand;
022    import org.jikesrvm.compilers.opt.ir.operand.Operand;
023    
024    /**
025     * An object that returns an estimate of the relative cost of spilling a
026     * symbolic register, based on basic block frequencies.
027     */
028    class BlockCountSpillCost extends SpillCostEstimator {
029    
030      BlockCountSpillCost(IR ir) {
031        calculate(ir);
032      }
033    
034      @Override
035      void calculate(IR ir) {
036        final double moveFactor = ir.options.REGALLOC_SIMPLE_SPILL_COST_MOVE_FACTOR;
037        final double memoryOperandFactor = ir.options.REGALLOC_SIMPLE_SPILL_COST_MEMORY_OPERAND_FACTOR;
038        for (Enumeration<BasicBlock> blocks = ir.getBasicBlocks(); blocks.hasMoreElements();) {
039          BasicBlock bb = blocks.nextElement();
040          float freq = bb.getExecutionFrequency();
041          for (Enumeration<Instruction> e = bb.forwardInstrEnumerator(); e.hasMoreElements();) {
042            Instruction s = e.nextElement();
043            double factor = freq;
044    
045            if (s.isMove()) factor *= moveFactor;
046            double baseFactor = factor;
047            if (SimpleSpillCost.hasBadSizeMemoryOperand(s)) {
048              baseFactor *= memoryOperandFactor;
049            }
050    
051            // first deal with non-memory operands
052            for (Enumeration<Operand> e2 = s.getRootOperands(); e2.hasMoreElements();) {
053              Operand op = e2.nextElement();
054              if (op.isRegister()) {
055                Register r = op.asRegister().getRegister();
056                if (r.isSymbolic()) {
057                  update(r, baseFactor);
058                }
059              }
060            }
061            // now handle memory operands
062            factor *= memoryOperandFactor;
063            for (Enumeration<Operand> e2 = s.getMemoryOperands(); e2.hasMoreElements();) {
064              MemoryOperand M = (MemoryOperand) e2.nextElement();
065              if (M.base != null) {
066                Register r = M.base.getRegister();
067                if (r.isSymbolic()) {
068                  update(r, factor);
069                }
070              }
071              if (M.index != null) {
072                Register r = M.index.getRegister();
073                if (r.isSymbolic()) {
074                  update(r, factor);
075                }
076              }
077            }
078          }
079        }
080      }
081    }