| /* |
| * 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.generational; |
| |
| import org.mmtk.plan.StopTheWorldConstraints; |
| |
| import org.mmtk.policy.CopySpace; |
| import org.mmtk.policy.Space; |
| |
| 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. */ |
| @Override |
| public boolean generational() { return true; } |
| |
| /** @return True if this plan moves objects. */ |
| @Override |
| public boolean movesObjects() { return true; } |
| |
| /** @return The number of header bits that are required. */ |
| @Override |
| public int gcHeaderBits() { return CopySpace.LOCAL_GC_BITS_REQUIRED; } |
| |
| /** @return The number of header words that are required. */ |
| @Override |
| public int gcHeaderWords() { return CopySpace.GC_HEADER_WORDS_REQUIRED; } |
| |
| /** @return True if this plan requires a write barrier */ |
| @Override |
| public boolean needsObjectReferenceWriteBarrier() { return true; } |
| |
| /** @return True if this plan requires a static barrier */ |
| @Override |
| public boolean needsObjectReferenceNonHeapWriteBarrier() { return Gen.USE_NON_HEAP_OBJECT_REFERENCE_WRITE_BARRIER; } |
| |
| /** @return True if this Plan can perform bulk object arraycopy barriers. */ |
| @Override |
| public boolean objectReferenceBulkCopySupported() { return true; } |
| |
| /** @return The specialized scan methods required */ |
| @Override |
| public int numSpecializedScans() { return 2; } |
| |
| /** @return True if this Plan requires a header bit for object logging */ |
| @Override |
| public boolean needsLogBitInHeader() { return Gen.USE_OBJECT_BARRIER; } |
| |
| /** |
| * @return The maximum size of an object that may be allocated directly into the nursery |
| */ |
| @Override |
| public int maxNonLOSDefaultAllocBytes() { |
| /* |
| * If the nursery is discontiguous, the maximum object is essentially unbounded. In |
| * a contiguous nursery, we can't attempt to nursery-allocate objects larger than the |
| * available nursery virtual memory. |
| */ |
| return Gen.USE_DISCONTIGUOUS_NURSERY ? |
| org.mmtk.utility.Constants.MAX_INT : |
| Space.getFracAvailable(Gen.NURSERY_VM_FRACTION).toInt(); |
| } |
| |
| } |