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.escape;
014    
015    import org.jikesrvm.classloader.RVMMethod;
016    
017    /**
018     * Hold semantic information about a method that is not defined in
019     * RVMMethod.
020     */
021    class MethodSummary {
022    
023      /**
024       * Is this method currently being analyzed?  Used for recursive
025       * invocations of the optimizing compiler.
026       */
027      private static boolean inProgress = false;
028    
029      /**
030       * Default escape result, that the result escapes but that no parameter is
031       * escaping.
032       */
033      private static final long RES_ESCAPE = 0x80000000;
034    
035      /**
036       * Escape result, top bit is result of the method bits 0..63 are for
037       * parameters 0..63 respectively
038       */
039      private long escapeInfo = RES_ESCAPE;
040    
041      /**
042       * @param m RVMMethod representing this method.
043       */
044      MethodSummary(RVMMethod m) { }
045    
046      /**
047       * Record that a parameter may or may not escape from a thread.
048       *
049       * @param p the number of the parameter
050       * @param b may it escape?
051       */
052      public void setParameterMayEscapeThread(int p, boolean b) {
053        if (p > 62) return; // all params past 62 escape!
054        long mask = 1L << p;
055        if (b) {
056          escapeInfo |= mask;
057        } else {
058          escapeInfo &= (~mask);
059        }
060      }
061    
062      /**
063       * Query whether a parameter may escape from a thread.
064       * @param p the number of the parameter
065       * @return false iff the parameter <em> must not </em> escape from the
066       * thread. true otherwise.
067       */
068      public boolean parameterMayEscapeThread(int p) {
069        if (p > 62) return true; // all params past 62 escape!
070        long mask = 1L << p;
071        return (escapeInfo & mask) != 0;
072      }
073    
074      /**
075       * Record that a result of this method may or may not escape from a thread.
076       *
077       * @param b may it escape?
078       */
079      public void setResultMayEscapeThread(boolean b) {
080        if (b) {
081          escapeInfo |= RES_ESCAPE;
082        } else {
083          escapeInfo &= ~RES_ESCAPE;
084        }
085      }
086    
087      /**
088       * Query whether the result of this method may escape from a thread.
089       * @return false iff the parameter <em> must not </em> escape from the
090       * thread. true otherwise.
091       */
092      public boolean resultMayEscapeThread() {
093        return (escapeInfo & RES_ESCAPE) != 0L;
094      }
095    
096      /**
097       * Is analysis of this method in progress?
098       */
099      public boolean inProgress() {
100        return inProgress;
101      }
102    
103      /**
104       * Mark that analysis of this method is or is not in progress.
105       * @param b
106       */
107      public void setInProgress(boolean b) {
108        inProgress = b;
109      }
110    }