1 /* 2 * Copyright (c) 2006, 2019, 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_OOPS_MARKWORD_INLINE_HPP 26 #define SHARE_OOPS_MARKWORD_INLINE_HPP 27 28 #include "oops/klass.hpp" 29 #include "oops/markWord.hpp" 30 #include "runtime/globals.hpp" 31 32 // Should this header be preserved during GC? 33 template <typename KlassProxy> 34 inline bool markWord::must_be_preserved(KlassProxy klass) const { 35 if (UseBiasedLocking) { 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 markWord prototype_header = prototype_for_klass(klass); 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 } 48 return (!is_unlocked() || !has_no_hash()); 49 } 50 51 // Should this header be preserved in the case of a promotion failure during scavenge? 52 template <typename KlassProxy> 53 inline bool markWord::must_be_preserved_for_promotion_failure(KlassProxy klass) 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(klass).has_bias_pattern()) { 65 return true; 66 } 67 } 68 return (!is_unlocked() || !has_no_hash()); 69 } 70 71 // Same as must_be_preserved_for_promotion_failure(). 72 inline bool markWord::must_be_preserved_for_cms_scavenge(Klass* klass_of_obj_containing_mark) const { 73 return must_be_preserved_for_promotion_failure(klass_of_obj_containing_mark); 74 } 75 76 inline markWord markWord::prototype_for_klass(const Klass* klass) { 77 markWord prototype_header = klass->prototype_header(); 78 assert(prototype_header == prototype() || prototype_header.has_bias_pattern(), "corrupt prototype header"); 79 80 return prototype_header; 81 } 82 83 #endif // SHARE_OOPS_MARKWORD_INLINE_HPP