| /* |
| * 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.Offset; |
| 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 { |
| |
| /**************************************************************************** |
| * |
| * Write and read barriers. By default do nothing, override if |
| * appropriate. |
| */ |
| |
| /** |
| * A new reference is about to be created. Take appropriate write |
| * barrier actions.<p> |
| * |
| * <b>By default do nothing, override if appropriate.</b> |
| * |
| * @param src The object into which the new reference will be stored |
| * @param slot The address into which the new reference will be |
| * stored. |
| * @param tgt The target of the new reference |
| * @param metaDataA A value that assists the host VM in creating a store |
| * @param metaDataB A value that assists the host VM in creating a store |
| * @param mode The context in which the store occurred |
| */ |
| @Inline |
| @Override |
| public void writeBarrier(ObjectReference src, Address slot, ObjectReference tgt, Word metaDataA, Word metaDataB, int mode) { |
| VM.barriers.performRawWriteInBarrier(src, slot, Poisoned.poison(tgt), metaDataA, metaDataB, mode); |
| } |
| |
| /** |
| * Attempt to atomically exchange the value in the given slot |
| * with the passed replacement value. If a new reference is |
| * created, we must then take appropriate write barrier actions.<p> |
| * |
| * <b>By default do nothing, override if appropriate.</b> |
| * |
| * @param src The object into which the new reference will be stored |
| * @param slot The address into which the new reference will be |
| * stored. |
| * @param old The old reference to be swapped out |
| * @param tgt The target of the new reference |
| * @param metaDataA A value that assists the host VM in creating a store |
| * @param metaDataB A value that assists the host VM in creating a store |
| * @param mode The context in which the store occurred |
| * @return True if the swap was successful. |
| */ |
| @Override |
| public boolean tryCompareAndSwapWriteBarrier(ObjectReference src, Address slot, ObjectReference old, ObjectReference tgt, |
| Word metaDataA, Word metaDataB, int mode) { |
| return VM.barriers.tryRawCompareAndSwapWriteInBarrier(src, slot, Poisoned.poison(old), Poisoned.poison(tgt), metaDataA, metaDataB, mode); |
| } |
| |
| /** |
| * A number of references are about to be copied from object |
| * <code>src</code> to object <code>dst</code> (as in an array |
| * copy). Thus, <code>dst</code> is the mutated object. Take |
| * appropriate write barrier actions.<p> |
| * |
| * @param src The source of the values to be copied |
| * @param srcOffset The offset of the first source address, in |
| * bytes, relative to <code>src</code> (in principle, this could be |
| * negative). |
| * @param dst The mutated object, i.e. the destination of the copy. |
| * @param dstOffset The offset of the first destination address, in |
| * bytes relative to <code>tgt</code> (in principle, this could be |
| * negative). |
| * @param bytes The size of the region being copied, in bytes. |
| * @return True if the update was performed by the barrier, false if |
| * left to the caller (always false in this case). |
| */ |
| @Override |
| public boolean writeBarrier(ObjectReference src, Offset srcOffset, ObjectReference dst, Offset dstOffset, int bytes) { |
| // TODO: Currently, read barriers implies that this is never used, perhaps |
| // we might want to use it sometime anyway? |
| if (VM.VERIFY_ASSERTIONS) VM.assertions._assert(false); |
| return false; |
| } |
| |
| /** |
| * Read a reference. Take appropriate read barrier action, and |
| * return the value that was read.<p> This is a <b>substituting<b> |
| * barrier. The call to this barrier takes the place of a load.<p> |
| * |
| * @param src The object reference holding the field being read. |
| * @param slot The address of the slot being read. |
| * @param metaDataA A value that assists the host VM in creating a load |
| * @param metaDataB A value that assists the host VM in creating a load |
| * @param mode The context in which the load occurred |
| * @return The reference that was read. |
| */ |
| @Inline |
| @Override |
| public ObjectReference readBarrier(ObjectReference src, Address slot, Word metaDataA, Word metaDataB, int mode) { |
| return Poisoned.depoison(VM.barriers.performRawReadInBarrier(src, slot, metaDataA, metaDataB, mode)); |
| } |
| } |