1 /*
  2  * Copyright (c) 2016, 2023, 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/workerThread.hpp"
 29 #include "gc/shared/workerUtils.hpp"
 30 #include "memory/allocation.inline.hpp"
 31 #include "memory/resourceArea.hpp"
 32 #include "oops/oop.inline.hpp"
 33 #include "runtime/atomic.hpp"
 34 #include "utilities/macros.hpp"
 35 
 36 void PreservedMarks::restore() {
 37   while (!_stack.is_empty()) {
 38     const OopAndMarkWord elem = _stack.pop();
 39     elem.set_mark();
 40   }
 41   assert_empty();
 42 }
 43 
 44 template <bool ALT_FWD>
 45 void PreservedMarks::adjust_during_full_gc_impl() {
 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(SlidingForwarding::forwardee<ALT_FWD>(obj));
 53     }
 54   }
 55 }
 56 
 57 void PreservedMarks::adjust_during_full_gc() {
 58   if (UseAltGCForwarding) {
 59     adjust_during_full_gc_impl<true>();
 60   } else {
 61     adjust_during_full_gc_impl<false>();
 62   }
 63 }
 64 
 65 void PreservedMarks::restore_and_increment(volatile size_t* const total_size_addr) {
 66   const size_t stack_size = size();
 67   restore();
 68   // Only do the atomic add if the size is > 0.
 69   if (stack_size > 0) {
 70     Atomic::add(total_size_addr, stack_size);
 71   }
 72 }
 73 
 74 #ifndef PRODUCT
 75 void PreservedMarks::assert_empty() {
 76   assert(_stack.is_empty(), "stack expected to be empty, size = " SIZE_FORMAT,
 77          _stack.size());
 78   assert(_stack.cache_size() == 0,
 79          "stack expected to have no cached segments, cache size = " SIZE_FORMAT,
 80          _stack.cache_size());
 81 }
 82 #endif // ndef PRODUCT
 83 
 84 void PreservedMarksSet::init(uint num) {
 85   assert(_stacks == nullptr && _num == 0, "do not re-initialize");
 86   assert(num > 0, "pre-condition");
 87   if (_in_c_heap) {
 88     _stacks = NEW_C_HEAP_ARRAY(Padded<PreservedMarks>, num, mtGC);
 89   } else {
 90     _stacks = NEW_RESOURCE_ARRAY(Padded<PreservedMarks>, num);
 91   }
 92   for (uint i = 0; i < num; i += 1) {
 93     ::new (_stacks + i) PreservedMarks();
 94   }
 95   _num = num;
 96 
 97   assert_empty();
 98 }
 99 
100 class RestorePreservedMarksTask : public WorkerTask {
101   PreservedMarksSet* const _preserved_marks_set;
102   SequentialSubTasksDone _sub_tasks;
103   volatile size_t _total_size;
104 #ifdef ASSERT
105   size_t _total_size_before;
106 #endif // ASSERT
107 
108 public:
109   void work(uint worker_id) override {
110     uint task_id = 0;
111     while (_sub_tasks.try_claim_task(task_id)) {
112       _preserved_marks_set->get(task_id)->restore_and_increment(&_total_size);
113     }
114   }
115 
116   RestorePreservedMarksTask(PreservedMarksSet* preserved_marks_set)
117     : WorkerTask("Restore Preserved Marks"),
118       _preserved_marks_set(preserved_marks_set),
119       _sub_tasks(preserved_marks_set->num()),
120       _total_size(0)
121       DEBUG_ONLY(COMMA _total_size_before(0)) {
122 #ifdef ASSERT
123     // This is to make sure the total_size we'll calculate below is correct.
124     for (uint i = 0; i < _preserved_marks_set->num(); ++i) {
125       _total_size_before += _preserved_marks_set->get(i)->size();
126     }
127 #endif // ASSERT
128   }
129 
130   ~RestorePreservedMarksTask() {
131     assert(_total_size == _total_size_before, "total_size = %zu before = %zu", _total_size, _total_size_before);
132     size_t mem_size = _total_size * (sizeof(oop) + sizeof(markWord));
133     log_trace(gc)("Restored %zu marks, occupying %zu %s", _total_size,
134                                                           byte_size_in_proper_unit(mem_size),
135                                                           proper_unit_for_byte_size(mem_size));
136   }
137 };
138 
139 void PreservedMarksSet::restore(WorkerThreads* workers) {
140   {
141     RestorePreservedMarksTask cl(this);
142     if (workers == nullptr) {
143       cl.work(0);
144     } else {
145       workers->run_task(&cl);
146     }
147   }
148 
149   assert_empty();
150 }
151 
152 WorkerTask* PreservedMarksSet::create_task() {
153   return new RestorePreservedMarksTask(this);
154 }
155 
156 void PreservedMarksSet::reclaim() {
157   assert_empty();
158 
159   for (uint i = 0; i < _num; i += 1) {
160     _stacks[i].~Padded<PreservedMarks>();
161   }
162 
163   if (_in_c_heap) {
164     FREE_C_HEAP_ARRAY(Padded<PreservedMarks>, _stacks);
165   } else {
166     // the array was resource-allocated, so nothing to do
167   }
168   _stacks = nullptr;
169   _num = 0;
170 }
171 
172 #ifndef PRODUCT
173 void PreservedMarksSet::assert_empty() {
174   assert(_stacks != nullptr && _num > 0, "should have been initialized");
175   for (uint i = 0; i < _num; i += 1) {
176     get(i)->assert_empty();
177   }
178 }
179 #endif // ndef PRODUCT
--- EOF ---