1 /* 2 * Copyright (c) 2006, 2010, 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. 22 * 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/klassOop.hpp" 30 #include "oops/markOop.hpp" 31 #include "runtime/globals.hpp" 32 33 // Should this header be preserved during GC? 34 inline 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 inline 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? 58 inline 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 76 inline 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? 85 inline 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 } 94 inline 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 } 99 100 inline 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