libgomp/single.c

   1 /* Copyright (C) 2005, 2008 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 Lesser General Public License as published by
   8    the Free Software Foundation; either version 2.1 of the License, or
   9    (at your option) 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 Lesser General Public License for
  14    more details.
  15
  16    You should have received a copy of the GNU Lesser General Public License
  17    along with libgomp; see the file COPYING.LIB.  If not, write to the
  18    Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
  19    MA 02110-1301, USA.  */
  20
  21 /* As a special exception, if you link this library with other files, some
  22    of which are compiled with GCC, to produce an executable, this library
  23    does not by itself cause the resulting executable to be covered by the
  24    GNU General Public License.  This exception does not however invalidate
  25    any other reasons why the executable file might be covered by the GNU
  26    General Public License.  */
  27
  28 /* This file handles the SINGLE construct.  */
  29
  30 #include "libgomp.h"
  31
  32
  33 /* This routine is called when first encountering a SINGLE construct that
  34    doesn't have a COPYPRIVATE clause.  Returns true if this is the thread
  35    that should execute the clause.  */
  36
  37 bool
  38 GOMP_single_start (void)
  39 {
  40 #ifdef HAVE_SYNC_BUILTINS
  41   struct gomp_thread *thr = gomp_thread ();
  42   struct gomp_team *team = thr->ts.team;
  43   unsigned long single_count;
  44
  45   if (__builtin_expect (team == NULL, 0))
  46     return true;
  47
  48   single_count = thr->ts.single_count++;
  49   return __sync_bool_compare_and_swap (&team->single_count, single_count,
  50                                        single_count + 1L);
  51 #else
  52   bool ret = gomp_work_share_start (false);
  53   if (ret)
  54     gomp_work_share_init_done ();
  55   gomp_work_share_end_nowait ();
  56   return ret;
  57 #endif
  58 }
  59
  60 /* This routine is called when first encountering a SINGLE construct that
  61    does have a COPYPRIVATE clause.  Returns NULL if this is the thread
  62    that should execute the clause; otherwise the return value is pointer
  63    given to GOMP_single_copy_end by the thread that did execute the clause.  */
  64
  65 void *
  66 GOMP_single_copy_start (void)
  67 {
  68   struct gomp_thread *thr = gomp_thread ();
  69
  70   bool first;
  71   void *ret;
  72
  73   first = gomp_work_share_start (false);
  74
  75   if (first)
  76     {
  77       gomp_work_share_init_done ();
  78       ret = NULL;
  79     }
  80   else
  81     {
  82       gomp_team_barrier_wait (&thr->ts.team->barrier);
  83
  84       ret = thr->ts.work_share->copyprivate;
  85       gomp_work_share_end_nowait ();
  86     }
  87
  88   return ret;
  89 }
  90
  91 /* This routine is called when the thread that entered a SINGLE construct
  92    with a COPYPRIVATE clause gets to the end of the construct.  */
  93
  94 void
  95 GOMP_single_copy_end (void *data)
  96 {
  97   struct gomp_thread *thr = gomp_thread ();
  98   struct gomp_team *team = thr->ts.team;
  99
 100   if (team != NULL)
 101     {
 102       thr->ts.work_share->copyprivate = data;
 103       gomp_team_barrier_wait (&team->barrier);
 104     }
 105
 106   gomp_work_share_end_nowait ();
 107 }