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 30 class ShenandoahForwarding { 31 public: 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