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;
014    
015    import org.mmtk.plan.TransitiveClosure;
016    
017    import org.vmmagic.pragma.*;
018    import org.vmmagic.unboxed.*;
019    
020    /**
021     * This class is the fundamental mechanism for performing a
022     * transitive closure over an object graph.<p>
023     *
024     * @see org.mmtk.plan.TraceLocal
025     */
026    @Uninterruptible
027    public final class RCZero extends TransitiveClosure {
028    
029      @Override
030      @Inline
031      public void processEdge(ObjectReference source, Address slot) {
032        slot.store(ObjectReference.nullReference());
033      }
034    }
035