1 /*
2 * Copyright (c) 2006, 2016, 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 #ifndef SHARE_VM_OOPS_MARKOOP_INLINE_HPP
26 #define SHARE_VM_OOPS_MARKOOP_INLINE_HPP
27
28 #include "oops/klass.hpp"
29 #include "oops/markOop.hpp"
30 #include "oops/oop.inline.hpp"
31 #include "runtime/globals.hpp"
32
33 // Should this header be preserved during GC (when biased locking is enabled)?
34 inline bool markOopDesc::must_be_preserved_with_bias(oop obj_containing_mark) const {
35 assert(UseBiasedLocking, "unexpected");
36 if (has_bias_pattern()) {
37 // Will reset bias at end of collection
38 // Mark words of biased and currently locked objects are preserved separately
39 return false;
40 }
41 markOop prototype_header = prototype_for_object(obj_containing_mark);
42 if (prototype_header->has_bias_pattern()) {
43 // Individual instance which has its bias revoked; must return
44 // true for correctness
45 return true;
46 }
47 return (!is_unlocked() || !has_no_hash());
48 }
49
50 // Should this header be preserved during GC?
51 inline bool markOopDesc::must_be_preserved(oop obj_containing_mark) const {
52 if (!UseBiasedLocking)
53 return (!is_unlocked() || !has_no_hash());
54 return must_be_preserved_with_bias(obj_containing_mark);
55 }
56
57 // Should this header be preserved in the case of a promotion failure
58 // during scavenge (when biased locking is enabled)?
59 inline bool markOopDesc::must_be_preserved_with_bias_for_promotion_failure(oop obj_containing_mark) const {
60 assert(UseBiasedLocking, "unexpected");
61 // We don't explicitly save off the mark words of biased and
62 // currently-locked objects during scavenges, so if during a
63 // promotion failure we encounter either a biased mark word or a
64 // klass which still has a biasable prototype header, we have to
65 // preserve the mark word. This results in oversaving, but promotion
66 // failures are rare, and this avoids adding more complex logic to
67 // the scavengers to call new variants of
68 // BiasedLocking::preserve_marks() / restore_marks() in the middle
69 // of a scavenge when a promotion failure has first been detected.
70 if (has_bias_pattern() ||
71 prototype_for_object(obj_containing_mark)->has_bias_pattern()) {
72 return true;
73 }
74 return (!is_unlocked() || !has_no_hash());
75 }
76
77 // Should this header be preserved in the case of a promotion failure
78 // during scavenge?
79 inline bool markOopDesc::must_be_preserved_for_promotion_failure(oop obj_containing_mark) const {
80 if (!UseBiasedLocking)
81 return (!is_unlocked() || !has_no_hash());
82 return must_be_preserved_with_bias_for_promotion_failure(obj_containing_mark);
83 }
84
85
86 // Same as must_be_preserved_with_bias_for_promotion_failure() except that
87 // it takes a Klass* argument, instead of the object of which this is the mark word.
88 inline bool markOopDesc::must_be_preserved_with_bias_for_cms_scavenge(Klass* klass_of_obj_containing_mark) const {
89 assert(UseBiasedLocking, "unexpected");
90 // CMS scavenges preserve mark words in similar fashion to promotion failures; see above
91 if (has_bias_pattern() ||
92 klass_of_obj_containing_mark->prototype_header()->has_bias_pattern()) {
93 return true;
94 }
95 return (!is_unlocked() || !has_no_hash());
96 }
97
98 // Same as must_be_preserved_for_promotion_failure() except that
99 // it takes a Klass* argument, instead of the object of which this is the mark word.
100 inline bool markOopDesc::must_be_preserved_for_cms_scavenge(Klass* klass_of_obj_containing_mark) const {
101 if (!UseBiasedLocking)
102 return (!is_unlocked() || !has_no_hash());
103 return must_be_preserved_with_bias_for_cms_scavenge(klass_of_obj_containing_mark);
104 }
105
106 inline markOop markOopDesc::prototype_for_object(oop obj) {
107 #ifdef ASSERT
108 markOop prototype_header = obj->klass()->prototype_header();
109 assert(prototype_header == prototype() || prototype_header->has_bias_pattern(), "corrupt prototype header");
110 #endif
111 return obj->klass()->prototype_header();
112 }
113
114 #endif // SHARE_VM_OOPS_MARKOOP_INLINE_HPP