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.
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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)?
34inline 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?
51inline 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)?
59inline 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?
79inline 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.
88inline 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.
100inline 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
106inline 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
115