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 */
013package org.mmtk.plan.refcount;
014
015import static org.mmtk.policy.SegregatedFreeListSpace.MAX_FREELIST_OBJECT_BYTES;
016import org.mmtk.plan.StopTheWorldConstraints;
017
018import 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
027public class RCBaseConstraints extends StopTheWorldConstraints {
028  @Override
029  public int gcHeaderBits() {
030    return RCHeader.GLOBAL_GC_BITS_REQUIRED;
031  }
032  @Override
033  public int gcHeaderWords() {
034    return RCHeader.GC_HEADER_WORDS_REQUIRED;
035  }
036  @Override
037  public boolean needsObjectReferenceWriteBarrier() {
038    return true;
039  }
040  @Override
041  public int maxNonLOSDefaultAllocBytes() {
042    return MAX_FREELIST_OBJECT_BYTES;
043  }
044  @Override
045  public boolean objectReferenceBulkCopySupported() {
046    return true;
047  }
048  /** @return {@code true} if we are building for generational reference counting */
049  public boolean buildForGenRC() {
050    return false;
051  }
052}