/*
* This file is part of the Jikes RVM project (http://jikesrvm.org).
*
* This file is licensed to You under the Common Public License (CPL);
* 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/cpl1.0.php
*
* See the COPYRIGHT.txt file distributed with this work for information
* regarding copyright ownership.
*/
package org.mmtk.plan.generational;
import org.mmtk.plan.StopTheWorldConstraints;
import org.mmtk.policy.CopySpace;
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 class GenConstraints extends StopTheWorldConstraints {
/** @return True if this plan is generational. */
public boolean generational() { return true; }
/** @return True if this plan moves objects. */
public boolean movesObjects() { return true; }
/** @return The number of header bits that are required. */
public int gcHeaderBits() { return CopySpace.LOCAL_GC_BITS_REQUIRED; }
/** @return The number of header words that are required. */
public int gcHeaderWords() { return CopySpace.GC_HEADER_WORDS_REQUIRED; }
/** @return True if this plan requires a write barrier */
public boolean needsWriteBarrier() { return true; }
/** @return True if this plan requires a static barrier */
public boolean needsStaticWriteBarrier() { return Gen.USE_STATIC_WRITE_BARRIER; }
/** @return The specialized scan methods required */
public int numSpecializedScans() { return 2; }
}