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.generational;
014    
015    import org.mmtk.plan.TransitiveClosure;
016    import org.mmtk.plan.refcount.RCHeader;
017    import org.mmtk.policy.Space;
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 GenRCModifiedProcessor extends TransitiveClosure {
030    
031        private final GenRCFindRootSetTraceLocal trace;
032    
033        public GenRCModifiedProcessor(GenRCFindRootSetTraceLocal trace) {
034          this.trace = trace;
035        }
036    
037      @Override
038      @Inline
039      public void processEdge(ObjectReference source, Address slot) {
040        ObjectReference object = slot.loadObjectReference();
041        if (!object.isNull()) {
042          if (Space.isInSpace(GenRC.NURSERY, object)) {
043            object = GenRC.nurserySpace.traceObject(trace, object, GenRC.ALLOC_RC);
044            RCHeader.incRC(object);
045            slot.store(object);
046          } else if (GenRC.isRCObject(object)) {
047            RCHeader.incRC(object);
048          }
049        }
050      }
051    }