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 static org.mmtk.policy.SegregatedFreeListSpace.MAX_FREELIST_OBJECT_BYTES;
016    import org.mmtk.plan.StopTheWorldConstraints;
017    
018    import org.vmmagic.pragma.*;
019    
020    /**
021     * This class and its subclasses communicate to the host VM/Runtime
022     * any features of the selected plan that it needs to know.  This is
023     * separate from the main Plan/PlanLocal class in order to bypass any
024     * issues with ordering of static initialization.
025     */
026    @Uninterruptible
027    public class RCBaseConstraints extends StopTheWorldConstraints {
028      @Override
029      public int gcHeaderBits() { return RCHeader.GLOBAL_GC_BITS_REQUIRED; }
030      @Override
031      public int gcHeaderWords() { return RCHeader.GC_HEADER_WORDS_REQUIRED; }
032      @Override
033      public boolean needsObjectReferenceWriteBarrier() { return true; }
034      @Override
035      public int maxNonLOSDefaultAllocBytes() { return MAX_FREELIST_OBJECT_BYTES; }
036      @Override
037      public boolean objectReferenceBulkCopySupported() { return true; }
038    
039      /** @return {@code true} if we are building for generational reference counting */
040      public boolean buildForGenRC() { return false; }
041    }