1/*
2 * Copyright (c) 2013, 2018, Red Hat, Inc. All rights reserved.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation.
7 *
8 * This code is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
11 * version 2 for more details (a copy is included in the LICENSE file that
12 * accompanied this code).
13 *
14 * You should have received a copy of the GNU General Public License version
15 * 2 along with this work; if not, write to the Free Software Foundation,
16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
17 *
18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
19 * or visit www.oracle.com if you need additional information or have any
20 * questions.
21 *
22 */
23
24#ifndef SHARE_GC_SHENANDOAH_SHENANDOAHFORWARDING_HPP
25#define SHARE_GC_SHENANDOAH_SHENANDOAHFORWARDING_HPP
26
27#include "oops/oop.hpp"
28#include "utilities/globalDefinitions.hpp"
29
30class ShenandoahForwarding {
31public:
32 /* Gets forwardee from the given object.
33 */
34 static inline oop get_forwardee(oop obj);
35
36 /* Returns the raw value from forwardee slot.
37 */
38 static inline HeapWord* get_forwardee_raw(oop obj);
39
40 /* Returns the raw value from forwardee slot without any checks.
41 * Used for quick verification.
42 */
43 static inline HeapWord* get_forwardee_raw_unchecked(oop obj);
44
45 /**
46 * Returns true if the object is forwarded, false otherwise.
47 */
48 static inline bool is_forwarded(oop obj);
49
50 /* Tries to atomically update forwardee in $holder object to $update.
51 * Assumes $holder points at itself.
52 * Asserts $holder is in from-space.
53 * Asserts $update is in to-space.
54 *
55 * Returns the new object 'update' upon success, or
56 * the new forwardee that a competing thread installed.
57 */
58 static inline oop try_update_forwardee(oop obj, oop update);
59
60};
61
62#endif // SHARE_GC_SHENANDOAH_SHENANDOAHFORWARDING_HPP
63