libjava/sysdep/s390/locks.h

   1 // locks.h - Thread synchronization primitives. S/390 implementation.
   2
   3 /* Copyright (C) 2002-2012  Free Software Foundation
   4
   5    This file is part of libgcj.
   6
   7 This software is copyrighted work licensed under the terms of the
   8 Libgcj License.  Please consult the file "LIBGCJ_LICENSE" for
   9 details.  */
  10
  11 #ifndef __SYSDEP_LOCKS_H__
  12 #define __SYSDEP_LOCKS_H__
  13
  14 typedef size_t obj_addr_t;      /* Integer type big enough for object   */
  15                                 /* address.                             */
  16
  17 // Atomically replace *addr by new_val if it was initially equal to old.
  18 // Return true if the comparison succeeded.
  19 // Assumed to have acquire semantics, i.e. later memory operations
  20 // cannot execute before the compare_and_swap finishes.
  21 inline static bool
  22 compare_and_swap(volatile obj_addr_t *addr,
  23                  obj_addr_t old, obj_addr_t new_val)
  24 {
  25   return __sync_bool_compare_and_swap (addr, old, new_val);
  26 }
  27
  28 // Set *addr to new_val with release semantics, i.e. making sure
  29 // that prior loads and stores complete before this
  30 // assignment.
  31 inline static void
  32 release_set(volatile obj_addr_t *addr, obj_addr_t new_val)
  33 {
  34   __sync_synchronize ();
  35   *(addr) = new_val;
  36 }
  37
  38 // Compare_and_swap with release semantics instead of acquire semantics.
  39 // On many architecture, the operation makes both guarantees, so the
  40 // implementation can be the same.
  41 inline static bool
  42 compare_and_swap_release(volatile obj_addr_t *addr,
  43                          obj_addr_t old, obj_addr_t new_val)
  44 {
  45   return compare_and_swap(addr, old, new_val);
  46 }
  47
  48 // Ensure that subsequent instructions do not execute on stale
  49 // data that was loaded from memory before the barrier.
  50 inline static void
  51 read_barrier()
  52 {
  53   __sync_synchronize ();
  54 }
  55
  56 // Ensure that prior stores to memory are completed with respect to other
  57 // processors.
  58 inline static void
  59 write_barrier()
  60 {
  61   __sync_synchronize ();
  62 }
  63 #endif