1 /*
   2  * Copyright (c) 2015, 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_INLINE_HPP
  25 #define SHARE_GC_SHENANDOAH_SHENANDOAHFORWARDING_INLINE_HPP
  26 
  27 #include "gc/shenandoah/shenandoahAsserts.hpp"
  28 #include "gc/shenandoah/shenandoahForwarding.hpp"
  29 #include "oops/markWord.inline.hpp"
  30 #include "runtime/atomic.hpp"
  31 
  32 inline HeapWord* ShenandoahForwarding::get_forwardee_raw(oop obj) {
  33   shenandoah_assert_in_heap(NULL, obj);
  34   return get_forwardee_raw_unchecked(obj);
  35 }
  36 
  37 inline HeapWord* ShenandoahForwarding::get_forwardee_raw_unchecked(oop obj) {
  38   markWord mark = obj->mark_raw();
  39   if (mark.is_marked()) {
  40     return (HeapWord*) mark.clear_lock_bits().to_pointer();
  41   } else {
  42     return (HeapWord*) obj;
  43   }
  44 }
  45 
  46 inline oop ShenandoahForwarding::get_forwardee(oop obj) {
  47   shenandoah_assert_correct(NULL, obj);
  48   return oop(get_forwardee_raw_unchecked(obj));
  49 }
  50 
  51 inline bool ShenandoahForwarding::is_forwarded(oop obj) {
  52   return obj->mark_raw().is_marked();
  53 }
  54 
  55 inline oop ShenandoahForwarding::try_update_forwardee(oop obj, oop update) {
  56   markWord old_mark = obj->mark_raw();
  57   if (old_mark.is_marked()) {
  58     return oop(old_mark.clear_lock_bits().to_pointer());
  59   }
  60 
  61   markWord new_mark = markWord::encode_pointer_as_mark(update);
  62   markWord prev_mark = obj->cas_set_mark_raw(new_mark, old_mark);
  63   if (prev_mark == old_mark) {
  64     return update;
  65   } else {
  66     return oop(prev_mark.clear_lock_bits().to_pointer());
  67   }
  68 }
  69 
  70 #endif // SHARE_GC_SHENANDOAH_SHENANDOAHFORWARDING_INLINE_HPP