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      1 /* Copyright (C) 2005-2022 Free Software Foundation, Inc.
      2    Contributed by Richard Henderson <rth (at) redhat.com>.
      3 
      4    This file is part of the GNU Offloading and Multi Processing Library
      5    (libgomp).
      6 
      7    Libgomp is free software; you can redistribute it and/or modify it
      8    under the terms of the GNU General Public License as published by
      9    the Free Software Foundation; either version 3, or (at your option)
     10    any later version.
     11 
     12    Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY
     13    WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
     14    FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
     15    more details.
     16 
     17    Under Section 7 of GPL version 3, you are granted additional
     18    permissions described in the GCC Runtime Library Exception, version
     19    3.1, as published by the Free Software Foundation.
     20 
     21    You should have received a copy of the GNU General Public License and
     22    a copy of the GCC Runtime Library Exception along with this program;
     23    see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
     24    <http://www.gnu.org/licenses/>.  */
     25 
     26 /* This file handles the SINGLE construct.  */
     27 
     28 #include "libgomp.h"
     29 
     30 
     31 /* This routine is called when first encountering a SINGLE construct that
     32    doesn't have a COPYPRIVATE clause.  Returns true if this is the thread
     33    that should execute the clause.  */
     34 
     35 bool
     36 GOMP_single_start (void)
     37 {
     38 #ifdef HAVE_SYNC_BUILTINS
     39   struct gomp_thread *thr = gomp_thread ();
     40   struct gomp_team *team = thr->ts.team;
     41   unsigned long single_count;
     42 
     43   if (__builtin_expect (team == NULL, 0))
     44     return true;
     45 
     46   single_count = thr->ts.single_count++;
     47   return __sync_bool_compare_and_swap (&team->single_count, single_count,
     48 				       single_count + 1L);
     49 #else
     50   bool ret = gomp_work_share_start (0);
     51   if (ret)
     52     gomp_work_share_init_done ();
     53   gomp_work_share_end_nowait ();
     54   return ret;
     55 #endif
     56 }
     57 
     58 /* This routine is called when first encountering a SINGLE construct that
     59    does have a COPYPRIVATE clause.  Returns NULL if this is the thread
     60    that should execute the clause; otherwise the return value is pointer
     61    given to GOMP_single_copy_end by the thread that did execute the clause.  */
     62 
     63 void *
     64 GOMP_single_copy_start (void)
     65 {
     66   struct gomp_thread *thr = gomp_thread ();
     67 
     68   bool first;
     69   void *ret;
     70 
     71   first = gomp_work_share_start (0);
     72 
     73   if (first)
     74     {
     75       gomp_work_share_init_done ();
     76       ret = NULL;
     77     }
     78   else
     79     {
     80       gomp_team_barrier_wait (&thr->ts.team->barrier);
     81 
     82       ret = thr->ts.work_share->copyprivate;
     83       gomp_work_share_end_nowait ();
     84     }
     85 
     86   return ret;
     87 }
     88 
     89 /* This routine is called when the thread that entered a SINGLE construct
     90    with a COPYPRIVATE clause gets to the end of the construct.  */
     91 
     92 void
     93 GOMP_single_copy_end (void *data)
     94 {
     95   struct gomp_thread *thr = gomp_thread ();
     96   struct gomp_team *team = thr->ts.team;
     97 
     98   if (team != NULL)
     99     {
    100       thr->ts.work_share->copyprivate = data;
    101       gomp_team_barrier_wait (&team->barrier);
    102     }
    103 
    104   gomp_work_share_end_nowait ();
    105 }
    106