/*
* 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 {
@Override
public boolean generational() {
return true;
}
@Override
public boolean movesObjects() {
return true;
}
@Override
public int gcHeaderBits() {
return CopySpace.LOCAL_GC_BITS_REQUIRED;
}
@Override
public int gcHeaderWords() {
return CopySpace.GC_HEADER_WORDS_REQUIRED;
}
@Override
public boolean needsObjectReferenceWriteBarrier() {
return true;
}
@Override
public boolean needsObjectReferenceNonHeapWriteBarrier() {
return Gen.USE_NON_HEAP_OBJECT_REFERENCE_WRITE_BARRIER;
}
@Override
public boolean objectReferenceBulkCopySupported() {
return true;
}
@Override
public int numSpecializedScans() {
return 2;
}
@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.
*/
long fracAvailable = Space.getFracAvailable(Gen.NURSERY_VM_FRACTION).toLong();
if (fracAvailable > org.mmtk.utility.Constants.MAX_INT) {
fracAvailable = org.mmtk.utility.Constants.MAX_INT;
}
return Gen.USE_DISCONTIGUOUS_NURSERY ?
org.mmtk.utility.Constants.MAX_INT :
(int)fracAvailable;
}
}