1 /* 2 * Copyright (c) 1997, 2008, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 # include "incls/_precompiled.incl" 26 # include "incls/_markOop.cpp.incl" 27 28 29 void markOopDesc::print_on(outputStream* st) const { 30 if (is_locked()) { 31 st->print("locked(0x%lx)->", value()); 32 markOop(*(markOop*)value())->print_on(st); 33 } else { 34 assert(is_unlocked() || has_bias_pattern(), "just checking"); 35 st->print("mark("); 36 if (has_bias_pattern()) st->print("biased,"); 37 st->print("hash %#lx,", hash()); 38 st->print("age %d)", age()); 39 } 40 } 41 42 43 // Give advice about whether the oop that contains this markOop 44 // should be cached or not. 45 bool markOopDesc::should_not_be_cached() const { 46 // the cast is because decode_pointer() isn't marked const 47 if (is_marked() && ((markOopDesc *)this)->decode_pointer() != NULL) { 48 // If the oop containing this markOop is being forwarded, then 49 // we are in the middle of GC and we do not want the containing 50 // oop to be added to a cache. We have no way of knowing whether 51 // the cache has already been visited by the current GC phase so 52 // we don't know whether the forwarded oop will be properly 53 // processed in this phase. If the forwarded oop is not properly 54 // processed, then we'll see strange crashes or asserts during 55 // the next GC run because the markOop will contain an unexpected 56 // value. 57 // 58 // This situation has been seen when we are GC'ing a methodOop 59 // because we use the methodOop while we're GC'ing it. Scary 60 // stuff. Some of the uses the methodOop cause the methodOop to 61 // be added to the OopMapCache in the instanceKlass as a side 62 // effect. This check lets the cache maintainer know when a 63 // cache addition would not be safe. 64 return true; 65 } 66 67 // caching the containing oop should be just fine 68 return false; 69 }