1 /*
2 * Copyright (c) 2006, 2019, 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.
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23 */
24
25 #ifndef SHARE_OOPS_MARKWORD_INLINE_HPP
26 #define SHARE_OOPS_MARKWORD_INLINE_HPP
27
28 #include "oops/markWord.hpp"
29
30 #include "oops/klass.hpp"
31 #include "oops/oop.inline.hpp"
32 #include "runtime/globals.hpp"
33
34 // Should this header be preserved during GC?
must_be_preserved(const oopDesc * obj) const35 inline bool markWord::must_be_preserved(const oopDesc* obj) const {
36 if (UseBiasedLocking) {
37 if (has_bias_pattern()) {
38 // Will reset bias at end of collection
39 // Mark words of biased and currently locked objects are preserved separately
40 return false;
41 }
42 markWord prototype_header = prototype_for_klass(obj->klass());
43 if (prototype_header.has_bias_pattern()) {
44 // Individual instance which has its bias revoked; must return
45 // true for correctness
46 return true;
47 }
48 }
49 return (!is_unlocked() || !has_no_hash());
50 }
51
52 // Should this header be preserved in the case of a promotion failure during scavenge?
must_be_preserved_for_promotion_failure(const oopDesc * obj) const53 inline bool markWord::must_be_preserved_for_promotion_failure(const oopDesc* obj) const {
54 if (UseBiasedLocking) {
55 // We don't explicitly save off the mark words of biased and
56 // currently-locked objects during scavenges, so if during a
57 // promotion failure we encounter either a biased mark word or a
58 // klass which still has a biasable prototype header, we have to
59 // preserve the mark word. This results in oversaving, but promotion
60 // failures are rare, and this avoids adding more complex logic to
61 // the scavengers to call new variants of
62 // BiasedLocking::preserve_marks() / restore_marks() in the middle
63 // of a scavenge when a promotion failure has first been detected.
64 if (has_bias_pattern() || prototype_for_klass(obj->klass()).has_bias_pattern()) {
65 return true;
66 }
67 }
68 return (!is_unlocked() || !has_no_hash());
69 }
70
prototype_for_klass(const Klass * klass)71 inline markWord markWord::prototype_for_klass(const Klass* klass) {
72 markWord prototype_header = klass->prototype_header();
73 assert(prototype_header == prototype() || prototype_header.has_bias_pattern(), "corrupt prototype header");
74
75 return prototype_header;
76 }
77
78 #endif // SHARE_OOPS_MARKWORD_INLINE_HPP
79