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