markOop.inline.hpp revision 1879:f95d63e2154a 
1/*
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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/klassOop.hpp"
30#include "oops/markOop.hpp"
31#include "runtime/globals.hpp"
32
33// Should this header be preserved during GC?
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
50inline bool markOopDesc::must_be_preserved(oop obj_containing_mark) const {
51  if (!UseBiasedLocking)
52    return (!is_unlocked() || !has_no_hash());
53  return must_be_preserved_with_bias(obj_containing_mark);
54}
55
56// Should this header (including its age bits) be preserved in the
57// case of a promotion failure during scavenge?
58inline bool markOopDesc::must_be_preserved_with_bias_for_promotion_failure(oop obj_containing_mark) const {
59  assert(UseBiasedLocking, "unexpected");
60  // We don't explicitly save off the mark words of biased and
61  // currently-locked objects during scavenges, so if during a
62  // promotion failure we encounter either a biased mark word or a
63  // klass which still has a biasable prototype header, we have to
64  // preserve the mark word. This results in oversaving, but promotion
65  // failures are rare, and this avoids adding more complex logic to
66  // the scavengers to call new variants of
67  // BiasedLocking::preserve_marks() / restore_marks() in the middle
68  // of a scavenge when a promotion failure has first been detected.
69  if (has_bias_pattern() ||
70      prototype_for_object(obj_containing_mark)->has_bias_pattern()) {
71    return true;
72  }
73  return (this != prototype());
74}
75
76inline bool markOopDesc::must_be_preserved_for_promotion_failure(oop obj_containing_mark) const {
77  if (!UseBiasedLocking)
78    return (this != prototype());
79  return must_be_preserved_with_bias_for_promotion_failure(obj_containing_mark);
80}
81
82
83// Should this header (including its age bits) be preserved in the
84// case of a scavenge in which CMS is the old generation?
85inline bool markOopDesc::must_be_preserved_with_bias_for_cms_scavenge(klassOop klass_of_obj_containing_mark) const {
86  assert(UseBiasedLocking, "unexpected");
87  // CMS scavenges preserve mark words in similar fashion to promotion failures; see above
88  if (has_bias_pattern() ||
89      klass_of_obj_containing_mark->klass_part()->prototype_header()->has_bias_pattern()) {
90    return true;
91  }
92  return (this != prototype());
93}
94inline bool markOopDesc::must_be_preserved_for_cms_scavenge(klassOop klass_of_obj_containing_mark) const {
95  if (!UseBiasedLocking)
96    return (this != prototype());
97  return must_be_preserved_with_bias_for_cms_scavenge(klass_of_obj_containing_mark);
98}
99
100inline markOop markOopDesc::prototype_for_object(oop obj) {
101#ifdef ASSERT
102  markOop prototype_header = obj->klass()->klass_part()->prototype_header();
103  assert(prototype_header == prototype() || prototype_header->has_bias_pattern(), "corrupt prototype header");
104#endif
105  return obj->klass()->klass_part()->prototype_header();
106}
107
108#endif // SHARE_VM_OOPS_MARKOOP_INLINE_HPP
109