Wed, 06 Jan 2010 22:21:39 -0800
Merge
1 /*
2 * Copyright 2006 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
25 // Should this header be preserved during GC?
26 inline bool markOopDesc::must_be_preserved_with_bias(oop obj_containing_mark) const {
27 assert(UseBiasedLocking, "unexpected");
28 if (has_bias_pattern()) {
29 // Will reset bias at end of collection
30 // Mark words of biased and currently locked objects are preserved separately
31 return false;
32 }
33 markOop prototype_header = prototype_for_object(obj_containing_mark);
34 if (prototype_header->has_bias_pattern()) {
35 // Individual instance which has its bias revoked; must return
36 // true for correctness
37 return true;
38 }
39 return (!is_unlocked() || !has_no_hash());
40 }
42 inline bool markOopDesc::must_be_preserved(oop obj_containing_mark) const {
43 if (!UseBiasedLocking)
44 return (!is_unlocked() || !has_no_hash());
45 return must_be_preserved_with_bias(obj_containing_mark);
46 }
48 // Should this header (including its age bits) be preserved in the
49 // case of a promotion failure during scavenge?
50 inline bool markOopDesc::must_be_preserved_with_bias_for_promotion_failure(oop obj_containing_mark) const {
51 assert(UseBiasedLocking, "unexpected");
52 // We don't explicitly save off the mark words of biased and
53 // currently-locked objects during scavenges, so if during a
54 // promotion failure we encounter either a biased mark word or a
55 // klass which still has a biasable prototype header, we have to
56 // preserve the mark word. This results in oversaving, but promotion
57 // failures are rare, and this avoids adding more complex logic to
58 // the scavengers to call new variants of
59 // BiasedLocking::preserve_marks() / restore_marks() in the middle
60 // of a scavenge when a promotion failure has first been detected.
61 if (has_bias_pattern() ||
62 prototype_for_object(obj_containing_mark)->has_bias_pattern()) {
63 return true;
64 }
65 return (this != prototype());
66 }
68 inline bool markOopDesc::must_be_preserved_for_promotion_failure(oop obj_containing_mark) const {
69 if (!UseBiasedLocking)
70 return (this != prototype());
71 return must_be_preserved_with_bias_for_promotion_failure(obj_containing_mark);
72 }
75 // Should this header (including its age bits) be preserved in the
76 // case of a scavenge in which CMS is the old generation?
77 inline bool markOopDesc::must_be_preserved_with_bias_for_cms_scavenge(klassOop klass_of_obj_containing_mark) const {
78 assert(UseBiasedLocking, "unexpected");
79 // CMS scavenges preserve mark words in similar fashion to promotion failures; see above
80 if (has_bias_pattern() ||
81 klass_of_obj_containing_mark->klass_part()->prototype_header()->has_bias_pattern()) {
82 return true;
83 }
84 return (this != prototype());
85 }
86 inline bool markOopDesc::must_be_preserved_for_cms_scavenge(klassOop klass_of_obj_containing_mark) const {
87 if (!UseBiasedLocking)
88 return (this != prototype());
89 return must_be_preserved_with_bias_for_cms_scavenge(klass_of_obj_containing_mark);
90 }
92 inline markOop markOopDesc::prototype_for_object(oop obj) {
93 #ifdef ASSERT
94 markOop prototype_header = obj->klass()->klass_part()->prototype_header();
95 assert(prototype_header == prototype() || prototype_header->has_bias_pattern(), "corrupt prototype header");
96 #endif
97 return obj->klass()->klass_part()->prototype_header();
98 }