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.mmtk.utility.sanitychecker;
014    
015    import org.mmtk.plan.TraceLocal;
016    import org.mmtk.plan.Trace;
017    import org.mmtk.vm.VM;
018    
019    import org.vmmagic.pragma.*;
020    import org.vmmagic.unboxed.*;
021    
022    /**
023     * This class implements the parallel root-gathering part of a sanity check.
024     */
025    @Uninterruptible
026    public final class SanityRootTraceLocal extends TraceLocal {
027    
028      /**
029       * Constructor
030       */
031      public SanityRootTraceLocal(Trace trace) {
032        super(trace);
033      }
034    
035      /****************************************************************************
036       *
037       * Object processing and tracing
038       */
039    
040      /**
041       * Copy root values across to the 'real' single-threaded trace that will do
042       * the sanity checking.
043       */
044      @Inline
045      public void copyRootValuesTo(TraceLocal trace) {
046        while (!rootLocations.isEmpty()) {
047          ObjectReference object = rootLocations.pop().loadObjectReference();
048          if (!object.isNull()) {
049            trace.traceObject(object, true);
050          }
051        }
052        while (!values.isEmpty()) {
053          trace.traceObject(values.pop(), true);
054        }
055      }
056    
057      /**
058       * Process delayed roots. This does not make sense for SanityRootTraceLocal.
059       * are empty.
060       */
061      @Override
062      @Inline
063      public void processRoots() {
064        VM.assertions.fail("SanityRootTraceLocal.processRoots called.");
065      }
066    
067      /**
068       * Finishing processing all GC work. This does not make sense for SanityRootTraceLocal.
069       */
070      @Override
071      @Inline
072      public void completeTrace() {
073        VM.assertions.fail("SanityRootTraceLocal.completeTrace called.");
074      }
075    
076      /**
077       * Trace a root object, i.e. root must be <code>true</code>.
078       */
079      @Override
080      @Inline
081      public ObjectReference traceObject(ObjectReference object, boolean root) {
082        if (!root) VM.assertions.fail("SanityRootTraceLocal.traceObject called for non-root object.");
083        if (!object.isNull()) {
084          values.push(object);
085        }
086        return object;
087      }
088    
089      /**
090       * Will this object move from this point on, during the current trace ?
091       *
092       * @param object The object to query.
093       * @return {@code true} if the object will not move.
094       */
095      @Override
096      public boolean willNotMoveInCurrentCollection(ObjectReference object) {
097        // We never move objects!
098        return true;
099      }
100    }