Mercurial > hg > graal-jvmci-8
view agent/src/share/classes/sun/jvm/hotspot/utilities/MarkBits.java @ 1385:bc32f286fae0
6945219: minor SA fixes
Reviewed-by: twisti
author | never |
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date | Tue, 20 Apr 2010 13:26:33 -0700 |
parents | a61af66fc99e |
children | c18cbe5936b8 |
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/* * Copyright 2001-2003 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.utilities; import sun.jvm.hotspot.debugger.*; import sun.jvm.hotspot.gc_interface.*; import sun.jvm.hotspot.memory.*; import sun.jvm.hotspot.oops.*; import sun.jvm.hotspot.runtime.*; /** Helper class which covers the reserved area of the heap with an (object-external) set of mark bits, used for GC-like scans through the heap like liveness analysis. */ public class MarkBits { public MarkBits(CollectedHeap heap) { MemRegion reserved = heap.reservedRegion(); // Must cover "reserved" with one bit for each OopHandle start = reserved.start(); end = reserved.end(); long numOopHandles = end.minus(start) / VM.getVM().getOopSize(); // FIXME: will have trouble with larger heap sizes bits = new BitMap((int) numOopHandles); } public void clear() { bits.clear(); } /** Returns true if a mark was newly placed for the given Oop, or false if the Oop was already marked. If the Oop happens to lie outside the heap (should not happen), prints a warning and returns false. */ public boolean mark(Oop obj) { if (obj == null) { System.err.println("MarkBits: WARNING: null object, ignoring"); return false; } OopHandle handle = obj.getHandle(); // FIXME: will have trouble with larger heap sizes long idx = handle.minus(start) / VM.getVM().getOopSize(); if ((idx < 0) || (idx >= bits.size())) { System.err.println("MarkBits: WARNING: object " + handle + " outside of heap, ignoring"); return false; } int intIdx = (int) idx; if (bits.at(intIdx)) { return false; // already marked } bits.atPut(intIdx, true); return true; } /** Forces clearing of a given mark bit. */ public void clear(Oop obj) { OopHandle handle = obj.getHandle(); // FIXME: will have trouble with larger heap sizes long idx = handle.minus(start) / VM.getVM().getOopSize(); if ((idx < 0) || (idx >= bits.size())) { System.err.println("MarkBits: WARNING: object " + handle + " outside of heap, ignoring"); return; } int intIdx = (int) idx; bits.atPut(intIdx, false); } private BitMap bits; private Address start; private Address end; }