vmkit/mmtk/java/src/org/mmtk/plan/PlanConstraints.java

/*
 *  This file is part of the Jikes RVM project (http://jikesrvm.org).
 *
 *  This file is licensed to You under the Eclipse Public License (EPL);
 *  You may not use this file except in compliance with the License. You
 *  may obtain a copy of the License at
 *
 *      http://www.opensource.org/licenses/eclipse-1.0.php
 *
 *  See the COPYRIGHT.txt file distributed with this work for information
 *  regarding copyright ownership.
 */
package org.mmtk.plan;

import org.mmtk.policy.SegregatedFreeListSpace;
import org.vmmagic.pragma.*;

/**
 * This class and its subclasses communicate to the host VM/Runtime
 * any features of the selected plan that it needs to know.  This is
 * separate from the main Plan/PlanLocal class in order to bypass any
 * issues with ordering of static initialization.
 */
@Uninterruptible public abstract class PlanConstraints {
  /** @return True if this Plan requires read barriers on java.lang.reference types. */
  public boolean needsJavaLangReferenceReadBarrier() { return false; }

  /** @return True if this Plan requires write barriers on booleans. */
  public boolean needsBooleanWriteBarrier() { return false; }

  /** @return True if this Plan requires read barriers on booleans. */
  public boolean needsBooleanReadBarrier() { return false; }

  /** @return True if this Plan can perform bulk boolean arraycopy barriers. */
  public boolean booleanBulkCopySupported() { return false; }

  /** @return True if this Plan requires write barriers on bytes. */
  public boolean needsByteWriteBarrier() { return false; }

  /** @return True if this Plan requires read barriers on bytes. */
  public boolean needsByteReadBarrier() { return false; }

  /** @return True if this Plan can perform bulk byte arraycopy barriers. */
  public boolean byteBulkCopySupported() { return false; }

  /** @return True if this Plan requires write barriers on chars. */
  public boolean needsCharWriteBarrier() { return false; }

  /** @return True if this Plan requires read barriers on chars. */
  public boolean needsCharReadBarrier() { return false; }

  /** @return True if this Plan can perform bulk char arraycopy barriers. */
  public boolean charBulkCopySupported() { return false; }

  /** @return True if this Plan requires write barriers on shorts. */
  public boolean needsShortWriteBarrier() { return false; }

  /** @return True if this Plan requires read barriers on shorts. */
  public boolean needsShortReadBarrier() { return false; }

  /** @return True if this Plan can perform bulk short arraycopy barriers. */
  public boolean shortBulkCopySupported() { return false; }

  /** @return True if this Plan requires write barriers on ints. */
  public boolean needsIntWriteBarrier() { return false; }

  /** @return True if this Plan requires read barriers on ints. */
  public boolean needsIntReadBarrier() { return false; }

  /** @return True if this Plan can perform bulk int arraycopy barriers. */
  public boolean intBulkCopySupported() { return false; }

  /** @return True if this Plan requires write barriers on longs. */
  public boolean needsLongWriteBarrier() { return false; }

  /** @return True if this Plan requires read barriers on longs. */
  public boolean needsLongReadBarrier() { return false; }

  /** @return True if this Plan can perform bulk long arraycopy barriers. */
  public boolean longBulkCopySupported() { return false; }

  /** @return True if this Plan requires write barriers on floats. */
  public boolean needsFloatWriteBarrier() { return false; }

  /** @return True if this Plan requires read barriers on floats. */
  public boolean needsFloatReadBarrier() { return false; }

  /** @return True if this Plan can perform bulk float arraycopy barriers. */
  public boolean floatBulkCopySupported() { return false; }

  /** @return True if this Plan requires write barriers on doubles. */
  public boolean needsDoubleWriteBarrier() { return false; }

  /** @return True if this Plan requires read barriers on doubles. */
  public boolean needsDoubleReadBarrier() { return false; }

  /** @return True if this Plan can perform bulk double arraycopy barriers. */
  public boolean doubleBulkCopySupported() { return false; }

  /** @return True if this Plan requires write barriers on Words. */
  public boolean needsWordWriteBarrier() { return false; }

  /** @return True if this Plan requires read barriers on Words. */
  public boolean needsWordReadBarrier() { return false; }

  /** @return True if this Plan can perform bulk Word arraycopy barriers. */
  public boolean wordBulkCopySupported() { return false; }

  /** @return True if this Plan requires write barriers on Address's. */
  public boolean needsAddressWriteBarrier() { return false; }

  /** @return True if this Plan requires read barriers on Address's. */
  public boolean needsAddressReadBarrier() { return false; }

  /** @return True if this Plan can perform bulk Address arraycopy barriers. */
  public boolean addressBulkCopySupported() { return false; }

  /** @return True if this Plan requires write barriers on Extents. */
  public boolean needsExtentWriteBarrier() { return false; }

  /** @return True if this Plan requires read barriers on Extents. */
  public boolean needsExtentReadBarrier() { return false; }

  /** @return True if this Plan can perform bulk Extent arraycopy barriers. */
  public boolean extentBulkCopySupported() { return false; }

  /** @return True if this Plan requires write barriers on Offsets. */
  public boolean needsOffsetWriteBarrier() { return false; }

  /** @return True if this Plan requires read barriers on Offsets. */
  public boolean needsOffsetReadBarrier() { return false; }

  /** @return True if this Plan can perform bulk Offset arraycopy barriers. */
  public boolean offsetBulkCopySupported() { return false; }

  /** @return True if this Plan requires write barriers on object references. */
  public boolean needsObjectReferenceWriteBarrier() { return false; }

  /** @return True if this Plan requires read barriers on object references. */
  public boolean needsObjectReferenceReadBarrier() { return false; }

  /** @return True if this Plan requires non-heap write barriers on object references. */
  public boolean needsObjectReferenceNonHeapWriteBarrier() { return false;}

  /** @return True if this Plan requires non-heap read barriers on object references. */
  public boolean needsObjectReferenceNonHeapReadBarrier() { return false; }

  /** @return True if this Plan can perform bulk object arraycopy barriers. */
  public boolean objectReferenceBulkCopySupported() { return false; }

  /** @return True if this Plan requires linear scanning. */
  public boolean needsLinearScan() { return org.mmtk.utility.Constants.SUPPORT_CARD_SCANNING;}

  /** @return True if this Plan does not support parallel collection. */
  public boolean noParallelGC() { return false;}

  /** @return True if this Plan moves objects. */
  public boolean movesObjects() { return false;}

  /** @return Size (in bytes) beyond which new regular objects must be allocated to the LOS */
  public int maxNonLOSDefaultAllocBytes() { return org.mmtk.utility.Constants.MAX_INT;}

  /** @return Size (in bytes) beyond which new non-moving objects must be allocated to the LOS */
  public int maxNonLOSNonMovingAllocBytes() { return SegregatedFreeListSpace.MAX_FREELIST_OBJECT_BYTES;}

  /** @return Size (in bytes) beyond which copied objects must be copied to the LOS */
  public int maxNonLOSCopyBytes() { return org.mmtk.utility.Constants.MAX_INT;}

  /** @return True if this object forwards objects <i>after</i>
   * determining global object liveness (e.g. many compacting collectors). */
  public boolean needsForwardAfterLiveness() { return false;}

  /** @return Is this plan generational in nature. */
  public boolean generational() { return false;}

  /** @return The number of header bits that are required. */
  public abstract int gcHeaderBits();

  /** @return The number of header words that are required. */
  public abstract int gcHeaderWords();

  /** @return True if this plan contains GCspy. */
  public boolean withGCspy() { return false; }

  /** @return True if this plan contains GCTrace. */
  public boolean generateGCTrace() { return false; }

  /** @return The specialized scan methods required */
  public int numSpecializedScans() { return 0; }

  /** @return True if this plan requires concurrent worker threads */
  public boolean needsConcurrentWorkers() { return false; }

  /** @return True if this Plan requires a header bit for object logging */
  public boolean needsLogBitInHeader() { return false; }
}