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/*
* Copyright (c) 2006, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
// Should this header be preserved during GC?
inline bool markOopDesc::must_be_preserved_with_bias(oop obj_containing_mark) const {
assert(UseBiasedLocking, "unexpected");
if (has_bias_pattern()) {
// Will reset bias at end of collection
// Mark words of biased and currently locked objects are preserved separately
return false;
}
markOop prototype_header = prototype_for_object(obj_containing_mark);
if (prototype_header->has_bias_pattern()) {
// Individual instance which has its bias revoked; must return
// true for correctness
return true;
}
return (!is_unlocked() || !has_no_hash());
}
inline bool markOopDesc::must_be_preserved(oop obj_containing_mark) const {
if (!UseBiasedLocking)
return (!is_unlocked() || !has_no_hash());
return must_be_preserved_with_bias(obj_containing_mark);
}
// Should this header (including its age bits) be preserved in the
// case of a promotion failure during scavenge?
inline bool markOopDesc::must_be_preserved_with_bias_for_promotion_failure(oop obj_containing_mark) const {
assert(UseBiasedLocking, "unexpected");
// We don't explicitly save off the mark words of biased and
// currently-locked objects during scavenges, so if during a
// promotion failure we encounter either a biased mark word or a
// klass which still has a biasable prototype header, we have to
// preserve the mark word. This results in oversaving, but promotion
// failures are rare, and this avoids adding more complex logic to
// the scavengers to call new variants of
// BiasedLocking::preserve_marks() / restore_marks() in the middle
// of a scavenge when a promotion failure has first been detected.
if (has_bias_pattern() ||
prototype_for_object(obj_containing_mark)->has_bias_pattern()) {
return true;
}
return (this != prototype());
}
inline bool markOopDesc::must_be_preserved_for_promotion_failure(oop obj_containing_mark) const {
if (!UseBiasedLocking)
return (this != prototype());
return must_be_preserved_with_bias_for_promotion_failure(obj_containing_mark);
}
// Should this header (including its age bits) be preserved in the
// case of a scavenge in which CMS is the old generation?
inline bool markOopDesc::must_be_preserved_with_bias_for_cms_scavenge(klassOop klass_of_obj_containing_mark) const {
assert(UseBiasedLocking, "unexpected");
// CMS scavenges preserve mark words in similar fashion to promotion failures; see above
if (has_bias_pattern() ||
klass_of_obj_containing_mark->klass_part()->prototype_header()->has_bias_pattern()) {
return true;
}
return (this != prototype());
}
inline bool markOopDesc::must_be_preserved_for_cms_scavenge(klassOop klass_of_obj_containing_mark) const {
if (!UseBiasedLocking)
return (this != prototype());
return must_be_preserved_with_bias_for_cms_scavenge(klass_of_obj_containing_mark);
}
inline markOop markOopDesc::prototype_for_object(oop obj) {
#ifdef ASSERT
markOop prototype_header = obj->klass()->klass_part()->prototype_header();
assert(prototype_header == prototype() || prototype_header->has_bias_pattern(), "corrupt prototype header");
#endif
return obj->klass()->klass_part()->prototype_header();
}
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