1 /*
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 3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 5  * This code is free software; you can redistribute it and/or modify it
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 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).
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15  * You should have received a copy of the GNU General Public License version
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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?
35 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?
53 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 
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