/*
 *  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.poisoned;

import org.mmtk.plan.marksweep.MSMutator;
import org.mmtk.vm.VM;

import org.vmmagic.pragma.*;
import org.vmmagic.unboxed.Address;
import org.vmmagic.unboxed.ObjectReference;
import org.vmmagic.unboxed.Word;

/**
 * This class implements a poisoned collector, that is essentially a test
 * case for read and write barriers in the VM.
 */
@Uninterruptible
public class PoisonedMutator extends MSMutator {

  @Override
  public void postAlloc(ObjectReference ref, ObjectReference typeRef, int bytes,
      int allocator) {
    VM.barriers.initializeObjectReferenceFields(ref, typeRef);
    super.postAlloc(ref, typeRef, bytes, allocator);
  }

  /****************************************************************************
   *
   * Write and read barriers. By default do nothing, override if
   * appropriate.
   */

  /**
   * {@inheritDoc}
   */
  @Inline
  @Override
  public void objectReferenceWrite(ObjectReference src, Address slot, ObjectReference tgt, Word metaDataA, Word metaDataB, int mode) {
    VM.barriers.wordWrite(src, Poisoned.poison(tgt), metaDataA, metaDataB, mode);
  }

  @Override
  public boolean objectReferenceTryCompareAndSwap(ObjectReference src, Address slot, ObjectReference old, ObjectReference tgt,
                                               Word metaDataA, Word metaDataB, int mode) {
    return VM.barriers.wordTryCompareAndSwap(src, Poisoned.poison(old), Poisoned.poison(tgt), metaDataA, metaDataB, mode);
  }

  @Inline
  @Override
  public ObjectReference objectReferenceRead(ObjectReference src, Address slot, Word metaDataA, Word metaDataB, int mode) {
    return Poisoned.depoison(VM.barriers.wordRead(src, metaDataA, metaDataB, mode));
  }
}