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