| /* |
| * 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.semispace.gctrace; |
| |
| import org.mmtk.plan.semispace.SSMutator; |
| import org.mmtk.plan.*; |
| import org.mmtk.utility.TraceGenerator; |
| import org.mmtk.vm.VM; |
| |
| import org.vmmagic.unboxed.*; |
| import org.vmmagic.pragma.*; |
| |
| /** |
| * This class implements <i>per-mutator thread</i> behavior and state for the |
| * <i>GCTrace</i> plan, which implements a GC tracing algorithm.<p> |
| * |
| * Specifically, this class defines <i>SS</i> mutator-time allocation, write |
| * barriers, and per-mutator collection semantics.<p> |
| * |
| * See {@link GCTrace} for an overview of the GC trace algorithm.<p> |
| * |
| * @see SSMutator |
| * @see GCTrace |
| * @see GCTraceCollector |
| * @see org.mmtk.plan.StopTheWorldMutator |
| * @see org.mmtk.plan.MutatorContext |
| */ |
| @Uninterruptible public class GCTraceMutator extends SSMutator { |
| |
| /**************************************************************************** |
| * |
| * Mutator-time allocation |
| */ |
| |
| /** |
| * Perform post-allocation actions. For many allocators none are |
| * required. |
| * |
| * @param object The newly allocated object |
| * @param typeRef the type reference for the instance being created |
| * @param bytes The size of the space to be allocated (in bytes) |
| * @param allocator The allocator number to be used for this allocation |
| */ |
| @Inline |
| public final void postAlloc(ObjectReference object, ObjectReference typeRef, |
| int bytes, int allocator) { |
| /* Make the trace generator aware of the new object. */ |
| TraceGenerator.addTraceObject(object, allocator); |
| |
| super.postAlloc(object, typeRef, bytes, allocator); |
| |
| /* Now have the trace process aware of the new allocation. */ |
| GCTrace.traceInducedGC = TraceGenerator.MERLIN_ANALYSIS; |
| TraceGenerator.traceAlloc(allocator == GCTrace.ALLOC_IMMORTAL, object, typeRef, bytes); |
| GCTrace.traceInducedGC = false; |
| } |
| |
| |
| /**************************************************************************** |
| * |
| * Write barrier. |
| */ |
| |
| /** |
| * A new reference is about to be created. Take appropriate write |
| * barrier actions.<p> |
| * |
| * In this case, we remember the address of the source of the |
| * pointer if the new reference points into the nursery from |
| * non-nursery space. |
| * |
| * @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 |
| * being modified |
| * @param mode The mode of the store (eg putfield, putstatic etc) |
| */ |
| @Inline |
| public final void writeBarrier(ObjectReference src, Address slot, |
| ObjectReference tgt, Word metaDataA, |
| Word metaDataB, int mode) { |
| TraceGenerator.processPointerUpdate(mode == PUTFIELD_WRITE_BARRIER, |
| src, slot, tgt); |
| VM.barriers.performWriteInBarrier(src, slot, 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 occured |
| * @return True if the swap was successful. |
| */ |
| @Inline |
| public boolean tryCompareAndSwapWriteBarrier(ObjectReference src, Address slot, |
| ObjectReference old, ObjectReference tgt, Word metaDataA, |
| Word metaDataB, int mode) { |
| boolean result = VM.barriers.tryCompareAndSwapWriteInBarrier(src, slot, old, tgt, metaDataA, metaDataB, mode); |
| if (result) { |
| TraceGenerator.processPointerUpdate(mode == PUTFIELD_WRITE_BARRIER, src, slot, tgt); |
| } |
| return result; |
| } |
| |
| /** |
| * 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). |
| */ |
| public boolean writeBarrier(ObjectReference src, Offset srcOffset, |
| ObjectReference dst, Offset dstOffset, int bytes) { |
| /* These names seem backwards, but are defined to be compatable with the |
| * previous writeBarrier method. */ |
| Address slot = dst.toAddress().plus(dstOffset); |
| Address tgtLoc = src.toAddress().plus(srcOffset); |
| for (int i = 0; i < bytes; i += BYTES_IN_ADDRESS) { |
| ObjectReference tgt = tgtLoc.loadObjectReference(); |
| TraceGenerator.processPointerUpdate(false, dst, slot, tgt); |
| slot = slot.plus(BYTES_IN_ADDRESS); |
| tgtLoc = tgtLoc.plus(BYTES_IN_ADDRESS); |
| } |
| return false; |
| } |
| |
| /**************************************************************************** |
| * |
| * Collection |
| */ |
| |
| /** |
| * Perform a per-mutator collection phase. |
| * |
| * @param phaseId The collection phase to perform |
| * @param primary perform any single-threaded local activities. |
| */ |
| public void collectionPhase(short phaseId, boolean primary) { |
| if (!GCTrace.traceInducedGC || |
| (phaseId != StopTheWorld.PREPARE) && |
| (phaseId != StopTheWorld.RELEASE)) { |
| // Delegate up. |
| super.collectionPhase(phaseId, primary); |
| } |
| } |
| } |