6687581: Make CMS work with compressed oops
Summary: Make FreeChunk read markword instead of LSB in _klass pointer to indicate that it's a FreeChunk for compressed oops.
Reviewed-by: ysr, jmasa
/*
* Copyright 2003 Sun Microsystems, Inc. All Rights Reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
* CA 95054 USA or visit www.sun.com if you need additional information or
* have any questions.
*
*/
package sun.jvm.hotspot.memory;
import java.util.*;
import sun.jvm.hotspot.debugger.*;
import sun.jvm.hotspot.types.*;
import sun.jvm.hotspot.runtime.*;
import sun.jvm.hotspot.oops.*;
public class FreeChunk extends VMObject {
static {
VM.registerVMInitializedObserver(new Observer() {
public void update(Observable o, Object data) {
initialize(VM.getVM().getTypeDataBase());
}
});
}
private static synchronized void initialize(TypeDataBase db) {
Type type = db.lookupType("FreeChunk");
nextField = type.getAddressField("_next");
prevField = type.getAddressField("_prev");
sizeField = type.getAddressField("_size");
}
// Fields
private static AddressField nextField;
private static AddressField prevField;
private static AddressField sizeField;
// Accessors
public FreeChunk next() {
return (FreeChunk) VMObjectFactory.newObject(FreeChunk.class, nextField.getValue(addr));
}
public FreeChunk prev() {
Address prev = prevField.getValue(addr).andWithMask(~0x3);
return (FreeChunk) VMObjectFactory.newObject(FreeChunk.class, prev);
}
public long size() {
if (VM.getVM().isCompressedOopsEnabled()) {
Mark mark = new Mark(sizeField.getValue(addr));
return mark.getSize();
} else {
Address size = sizeField.getValue(addr);
Debugger dbg = VM.getVM().getDebugger();
return dbg.getAddressValue(size);
}
}
public FreeChunk(Address addr) {
super(addr);
}
public static boolean indicatesFreeChunk(Address cur) {
FreeChunk f = new FreeChunk(cur);
return f.isFree();
}
public boolean isFree() {
if (VM.getVM().isCompressedOopsEnabled()) {
Mark mark = new Mark(sizeField.getValue(addr));
return mark.isCmsFreeChunk();
} else {
Address prev = prevField.getValue(addr);
Debugger dbg = VM.getVM().getDebugger();
long word = dbg.getAddressValue(prev);
return (word & 0x1L) == 0x1L;
}
}
}