markOop.inline.hpp revision 1472:c18cbe5936b8 
1/*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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7 * published by the Free Software Foundation.
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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.
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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23 */
24
25// Should this header be preserved during GC?
26inline 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}
41
42inline 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}
47
48// Should this header (including its age bits) be preserved in the
49// case of a promotion failure during scavenge?
50inline 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}
67
68inline 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}
73
74
75// Should this header (including its age bits) be preserved in the
76// case of a scavenge in which CMS is the old generation?
77inline 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}
86inline 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}
91
92inline 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}
99