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80 lines
2.5 KiB
C++
80 lines
2.5 KiB
C++
/*
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* Copyright (c) 2015, 2021, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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#include "precompiled.hpp"
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#include "gc/x/xBarrier.inline.hpp"
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#include "gc/x/xRootsIterator.hpp"
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#include "gc/x/xTask.hpp"
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#include "gc/x/xWeakRootsProcessor.hpp"
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#include "gc/x/xWorkers.hpp"
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class XPhantomCleanOopClosure : public OopClosure {
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public:
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virtual void do_oop(oop* p) {
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// Read the oop once, to make sure the liveness check
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// and the later clearing uses the same value.
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const oop obj = Atomic::load(p);
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if (XBarrier::is_alive_barrier_on_phantom_oop(obj)) {
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XBarrier::keep_alive_barrier_on_phantom_oop_field(p);
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} else {
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// The destination could have been modified/reused, in which case
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// we don't want to clear it. However, no one could write the same
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// oop here again (the object would be strongly live and we would
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// not consider clearing such oops), so therefore we don't have an
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// ABA problem here.
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Atomic::cmpxchg(p, obj, oop(nullptr));
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}
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}
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virtual void do_oop(narrowOop* p) {
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ShouldNotReachHere();
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}
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};
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XWeakRootsProcessor::XWeakRootsProcessor(XWorkers* workers) :
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_workers(workers) {}
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class XProcessWeakRootsTask : public XTask {
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private:
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XWeakRootsIterator _weak_roots;
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public:
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XProcessWeakRootsTask() :
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XTask("XProcessWeakRootsTask"),
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_weak_roots() {}
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~XProcessWeakRootsTask() {
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_weak_roots.report_num_dead();
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}
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virtual void work() {
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XPhantomCleanOopClosure cl;
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_weak_roots.apply(&cl);
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}
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};
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void XWeakRootsProcessor::process_weak_roots() {
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XProcessWeakRootsTask task;
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_workers->run(&task);
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}
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