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.controlflow;
014    
015    import org.jikesrvm.compilers.opt.DefUse;
016    import org.jikesrvm.compilers.opt.OptOptions;
017    import org.jikesrvm.compilers.opt.driver.CompilerPhase;
018    import org.jikesrvm.compilers.opt.ir.IR;
019    
020    /**
021     * The driver that creates an annotated {@link AnnotatedLSTGraph}.
022     *
023     * @see AnnotatedLSTGraph
024     */
025    public class LoopAnalysis extends CompilerPhase {
026      /**
027       * Return a string name for this phase.
028       * @return "Loop Analysis"
029       */
030      public final String getName() {
031        return "Loop Analysis";
032      }
033    
034      /**
035       * Should the optimisation be performed
036       */
037      public boolean shouldPerform(OptOptions options) {
038        return options.getOptLevel() >= 3;
039      }
040    
041      /**
042       * The main entry point
043       * @param ir the IR to process
044       */
045      public final void perform(IR ir) {
046        if (!ir.hasReachableExceptionHandlers()) {
047          // Build LST tree and dominator info
048          new DominatorsPhase(false).perform(ir);
049          DefUse.computeDU(ir);
050          // Build annotated version
051          ir.HIRInfo.loopStructureTree = new AnnotatedLSTGraph(ir, ir.HIRInfo.loopStructureTree);
052        }
053      }
054    }