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.immix;
014    
015    import org.mmtk.plan.StopTheWorldConstraints;
016    import org.mmtk.policy.immix.ObjectHeader;
017    import static org.mmtk.policy.immix.ImmixConstants.MAX_IMMIX_OBJECT_BYTES;
018    
019    import org.vmmagic.pragma.*;
020    
021    /**
022     * This class and its subclasses communicate to the host VM/Runtime
023     * any features of the selected plan that it needs to know.  This is
024     * separate from the main Plan/PlanLocal class in order to bypass any
025     * issues with ordering of static initialization.
026     */
027    @Uninterruptible
028    public class ImmixConstraints extends StopTheWorldConstraints {
029    
030      @Override
031      public int gcHeaderBits() { return ObjectHeader.LOCAL_GC_BITS_REQUIRED; }
032    
033      @Override
034      public int gcHeaderWords() { return ObjectHeader.GC_HEADER_WORDS_REQUIRED; }
035    
036      @Override
037      public boolean movesObjects() { return true;}
038    
039      @Override
040      public int numSpecializedScans() { return 2; }
041    
042      @Override
043      public int maxNonLOSDefaultAllocBytes() { return MAX_IMMIX_OBJECT_BYTES; }
044    
045      @Override
046      public int maxNonLOSCopyBytes() { return MAX_IMMIX_OBJECT_BYTES; }
047    }