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.fullheap;
014    
015    import org.mmtk.plan.TransitiveClosure;
016    import org.mmtk.plan.refcount.RCBase;
017    import org.mmtk.plan.refcount.RCHeader;
018    
019    import org.vmmagic.pragma.*;
020    import org.vmmagic.unboxed.*;
021    
022    /**
023     * This class is the fundamental mechanism for performing a
024     * transitive closure over an object graph.<p>
025     *
026     * @see org.mmtk.plan.TraceLocal
027     */
028    @Uninterruptible
029    public final class RCModifiedProcessor extends TransitiveClosure {
030    
031      private RCCollector collector;
032    
033      public RCModifiedProcessor(RCCollector ctor) {
034        this.collector = ctor;
035      }
036    
037      @Override
038      @Inline
039      public void processEdge(ObjectReference source, Address slot) {
040        ObjectReference object = slot.loadObjectReference();
041        if (RCBase.isRCObject(object)) {
042          if (RCBase.CC_BACKUP_TRACE && RCBase.performCycleCollection) {
043            if (RCHeader.remainRC(object) == RCHeader.INC_NEW) {
044              collector.getModBuffer().push(object);
045            }
046          } else {
047            if (RCHeader.incRC(object) == RCHeader.INC_NEW) {
048              collector.getModBuffer().push(object);
049            }
050          }
051        }
052      }
053    }