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.plan.refcount.backuptrace;
014    
015    import org.mmtk.plan.refcount.RCHeader;
016    import org.mmtk.policy.ExplicitLargeObjectSpace;
017    import org.mmtk.vm.VM;
018    
019    import org.vmmagic.pragma.*;
020    import org.vmmagic.unboxed.*;
021    
022    /**
023     * This class implements the scanning of dead large objects during a backup trace.
024     */
025    @Uninterruptible
026    public final class BTScanLargeObjectSweeper extends ExplicitLargeObjectSpace.Sweeper {
027    
028      private final BTDecMarked sdm = new BTDecMarked();
029    
030      public boolean sweepLargeObject(ObjectReference object) {
031        if (!RCHeader.isMarked(object)) {
032          VM.scanning.scanObject(sdm, object);
033        }
034        // Do not free any objects at this time
035        return false;
036      }
037    }