1 /* 2 * Copyright (c) 2016, 2021, 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 #include "precompiled.hpp" 26 #include "gc/shared/preservedMarks.inline.hpp" 27 #include "gc/shared/slidingForwarding.inline.hpp" 28 #include "gc/shared/workgroup.hpp" 29 #include "memory/allocation.inline.hpp" 30 #include "memory/resourceArea.hpp" 31 #include "oops/oop.inline.hpp" 32 #include "runtime/atomic.hpp" 33 #include "utilities/macros.hpp" 34 35 void PreservedMarks::restore() { 36 while (!_stack.is_empty()) { 37 const OopAndMarkWord elem = _stack.pop(); 38 elem.set_mark(); 39 } 40 assert_empty(); 41 } 42 43 // TODO: This method is unused, except in the gunit test. Change the test 44 // to exercise the updated method below instead, and remove this one. 45 void PreservedMarks::adjust_during_full_gc() { 46 StackIterator<OopAndMarkWord, mtGC> iter(_stack); 47 while (!iter.is_empty()) { 48 OopAndMarkWord* elem = iter.next_addr(); 49 50 oop obj = elem->get_oop(); 51 if (obj->is_forwarded()) { 52 elem->set_oop(obj->forwardee()); 53 } 54 } 55 } 56 57 void PreservedMarks::adjust_during_full_gc(const SlidingForwarding* const forwarding) { 58 StackIterator<OopAndMarkWord, mtGC> iter(_stack); 59 while (!iter.is_empty()) { 60 OopAndMarkWord* elem = iter.next_addr(); 61 62 oop obj = elem->get_oop(); 63 if (obj->is_forwarded()) { 64 elem->set_oop(forwarding->forwardee(obj)); 65 } 66 } 67 } 68 69 void PreservedMarks::restore_and_increment(volatile size_t* const total_size_addr) { 70 const size_t stack_size = size(); 71 restore(); 72 // Only do the atomic add if the size is > 0. 73 if (stack_size > 0) { 74 Atomic::add(total_size_addr, stack_size); 75 } 76 } 77 78 #ifndef PRODUCT 79 void PreservedMarks::assert_empty() { 80 assert(_stack.is_empty(), "stack expected to be empty, size = " SIZE_FORMAT, 81 _stack.size()); 82 assert(_stack.cache_size() == 0, 83 "stack expected to have no cached segments, cache size = " SIZE_FORMAT, 84 _stack.cache_size()); 85 } 86 #endif // ndef PRODUCT 87 88 void RemoveForwardedPointerClosure::do_object(oop obj) { 89 if (obj->is_forwarded()) { 90 #ifdef _LP64 91 if (UseCompactObjectHeaders) { 92 oop forwardee = obj->forwardee(); 93 markWord header = forwardee->mark(); 94 if (header.has_displaced_mark_helper()) { 95 header = header.displaced_mark_helper(); 96 } 97 assert(UseCompressedClassPointers, "assume +UseCompressedClassPointers"); 98 narrowKlass nklass = header.narrow_klass(); 99 obj->set_mark(markWord::prototype().set_narrow_klass(nklass)); 100 } else 101 #endif 102 { 103 PreservedMarks::init_forwarded_mark(obj); 104 } 105 } 106 } 107 108 void PreservedMarksSet::init(uint num) { 109 assert(_stacks == nullptr && _num == 0, "do not re-initialize"); 110 assert(num > 0, "pre-condition"); 111 if (_in_c_heap) { 112 _stacks = NEW_C_HEAP_ARRAY(Padded<PreservedMarks>, num, mtGC); 113 } else { 114 _stacks = NEW_RESOURCE_ARRAY(Padded<PreservedMarks>, num); 115 } 116 for (uint i = 0; i < num; i += 1) { 117 ::new (_stacks + i) PreservedMarks(); 118 } 119 _num = num; 120 121 assert_empty(); 122 } 123 124 class RestorePreservedMarksTask : public AbstractGangTask { 125 PreservedMarksSet* const _preserved_marks_set; 126 SequentialSubTasksDone _sub_tasks; 127 volatile size_t _total_size; 128 #ifdef ASSERT 129 size_t _total_size_before; 130 #endif // ASSERT 131 132 public: 133 void work(uint worker_id) override { 134 uint task_id = 0; 135 while (_sub_tasks.try_claim_task(task_id)) { 136 _preserved_marks_set->get(task_id)->restore_and_increment(&_total_size); 137 } 138 } 139 140 RestorePreservedMarksTask(PreservedMarksSet* preserved_marks_set) 141 : AbstractGangTask("Restore Preserved Marks"), 142 _preserved_marks_set(preserved_marks_set), 143 _sub_tasks(preserved_marks_set->num()), 144 _total_size(0) 145 DEBUG_ONLY(COMMA _total_size_before(0)) { 146 #ifdef ASSERT 147 // This is to make sure the total_size we'll calculate below is correct. 148 for (uint i = 0; i < _preserved_marks_set->num(); ++i) { 149 _total_size_before += _preserved_marks_set->get(i)->size(); 150 } 151 #endif // ASSERT 152 } 153 154 ~RestorePreservedMarksTask() { 155 assert(_total_size == _total_size_before, "total_size = %zu before = %zu", _total_size, _total_size_before); 156 157 log_trace(gc)("Restored %zu marks", _total_size); 158 } 159 }; 160 161 void PreservedMarksSet::restore(WorkGang* workers) { 162 { 163 RestorePreservedMarksTask cl(this); 164 if (workers == nullptr) { 165 cl.work(0); 166 } else { 167 workers->run_task(&cl); 168 } 169 } 170 171 assert_empty(); 172 } 173 174 AbstractGangTask* PreservedMarksSet::create_task() { 175 return new RestorePreservedMarksTask(this); 176 } 177 178 void PreservedMarksSet::reclaim() { 179 assert_empty(); 180 181 for (uint i = 0; i < _num; i += 1) { 182 _stacks[i].~Padded<PreservedMarks>(); 183 } 184 185 if (_in_c_heap) { 186 FREE_C_HEAP_ARRAY(Padded<PreservedMarks>, _stacks); 187 } else { 188 // the array was resource-allocated, so nothing to do 189 } 190 _stacks = nullptr; 191 _num = 0; 192 } 193 194 #ifndef PRODUCT 195 void PreservedMarksSet::assert_empty() { 196 assert(_stacks != nullptr && _num > 0, "should have been initialized"); 197 for (uint i = 0; i < _num; i += 1) { 198 get(i)->assert_empty(); 199 } 200 } 201 #endif // ndef PRODUCT