libgomp/single.c

   1 /* Copyright (C) 2005-2015 Free Software Foundation, Inc.
   2    Contributed by Richard Henderson <rth@redhat.com>.
   3
   4    This file is part of the GNU OpenMP Library (libgomp).
   5
   6    Libgomp is free software; you can redistribute it and/or modify it
   7    under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3, or (at your option)
   9    any later version.
  10
  11    Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY
  12    WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  13    FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  14    more details.
  15
  16    Under Section 7 of GPL version 3, you are granted additional
  17    permissions described in the GCC Runtime Library Exception, version
  18    3.1, as published by the Free Software Foundation.
  19
  20    You should have received a copy of the GNU General Public License and
  21    a copy of the GCC Runtime Library Exception along with this program;
  22    see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  23    <http://www.gnu.org/licenses/>.  */
  24
  25 /* This file handles the SINGLE construct.  */
  26
  27 #include "libgomp.h"
  28
  29
  30 /* This routine is called when first encountering a SINGLE construct that
  31    doesn't have a COPYPRIVATE clause.  Returns true if this is the thread
  32    that should execute the clause.  */
  33
  34 bool
  35 GOMP_single_start (void)
  36 {
  37 #ifdef HAVE_SYNC_BUILTINS
  38   struct gomp_thread *thr = gomp_thread ();
  39   struct gomp_team *team = thr->ts.team;
  40   unsigned long single_count;
  41
  42   if (__builtin_expect (team == NULL, 0))
  43     return true;
  44
  45   single_count = thr->ts.single_count++;
  46   return __sync_bool_compare_and_swap (&team->single_count, single_count,
  47                                        single_count + 1L);
  48 #else
  49   bool ret = gomp_work_share_start (false);
  50   if (ret)
  51     gomp_work_share_init_done ();
  52   gomp_work_share_end_nowait ();
  53   return ret;
  54 #endif
  55 }
  56
  57 /* This routine is called when first encountering a SINGLE construct that
  58    does have a COPYPRIVATE clause.  Returns NULL if this is the thread
  59    that should execute the clause; otherwise the return value is pointer
  60    given to GOMP_single_copy_end by the thread that did execute the clause.  */
  61
  62 void *
  63 GOMP_single_copy_start (void)
  64 {
  65   struct gomp_thread *thr = gomp_thread ();
  66
  67   bool first;
  68   void *ret;
  69
  70   first = gomp_work_share_start (false);
  71
  72   if (first)
  73     {
  74       gomp_work_share_init_done ();
  75       ret = NULL;
  76     }
  77   else
  78     {
  79       gomp_team_barrier_wait (&thr->ts.team->barrier);
  80
  81       ret = thr->ts.work_share->copyprivate;
  82       gomp_work_share_end_nowait ();
  83     }
  84
  85   return ret;
  86 }
  87
  88 /* This routine is called when the thread that entered a SINGLE construct
  89    with a COPYPRIVATE clause gets to the end of the construct.  */
  90
  91 void
  92 GOMP_single_copy_end (void *data)
  93 {
  94   struct gomp_thread *thr = gomp_thread ();
  95   struct gomp_team *team = thr->ts.team;
  96
  97   if (team != NULL)
  98     {
  99       thr->ts.work_share->copyprivate = data;
 100       gomp_team_barrier_wait (&team->barrier);
 101     }
 102
 103   gomp_work_share_end_nowait ();
 104 }