sections.c revision 171831 
1/* Copyright (C) 2005, 2007 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 SECTIONS construct.  */
29
30#include "libgomp.h"
31
32
33/* Initialize the given work share construct from the given arguments.  */
34
35static inline void
36gomp_sections_init (struct gomp_work_share *ws, unsigned count)
37{
38  ws->sched = GFS_DYNAMIC;
39  ws->chunk_size = 1;
40  ws->end = count + 1;
41  ws->incr = 1;
42  ws->next = 1;
43}
44
45/* This routine is called when first encountering a sections construct
46   that is not bound directly to a parallel construct.  The first thread
47   that arrives will create the work-share construct; subsequent threads
48   will see the construct exists and allocate work from it.
49
50   COUNT is the number of sections in this construct.
51
52   Returns the 1-based section number for this thread to perform, or 0 if
53   all work was assigned to other threads prior to this thread's arrival.  */
54
55unsigned
56GOMP_sections_start (unsigned count)
57{
58  struct gomp_thread *thr = gomp_thread ();
59  long s, e, ret;
60
61  if (gomp_work_share_start (false))
62    gomp_sections_init (thr->ts.work_share, count);
63
64  if (gomp_iter_dynamic_next_locked (&s, &e))
65    ret = s;
66  else
67    ret = 0;
68
69  gomp_mutex_unlock (&thr->ts.work_share->lock);
70
71  return ret;
72}
73
74/* This routine is called when the thread completes processing of the
75   section currently assigned to it.  If the work-share construct is
76   bound directly to a parallel construct, then the construct may have
77   been set up before the parallel.  In which case, this may be the
78   first iteration for the thread.
79
80   Returns the 1-based section number for this thread to perform, or 0 if
81   all work was assigned to other threads prior to this thread's arrival.  */
82
83unsigned
84GOMP_sections_next (void)
85{
86  struct gomp_thread *thr = gomp_thread ();
87  long s, e, ret;
88
89  gomp_mutex_lock (&thr->ts.work_share->lock);
90  if (gomp_iter_dynamic_next_locked (&s, &e))
91    ret = s;
92  else
93    ret = 0;
94  gomp_mutex_unlock (&thr->ts.work_share->lock);
95
96  return ret;
97}
98
99/* This routine pre-initializes a work-share construct to avoid one
100   synchronization once we get into the loop.  */
101
102void
103GOMP_parallel_sections_start (void (*fn) (void *), void *data,
104			      unsigned num_threads, unsigned count)
105{
106  struct gomp_work_share *ws;
107
108  num_threads = gomp_resolve_num_threads (num_threads);
109  if (gomp_dyn_var && num_threads > count)
110    num_threads = count;
111
112  ws = gomp_new_work_share (false, num_threads);
113  gomp_sections_init (ws, count);
114  gomp_team_start (fn, data, num_threads, ws);
115}
116
117/* The GOMP_section_end* routines are called after the thread is told
118   that all sections are complete.  This first version synchronizes
119   all threads; the nowait version does not.  */
120
121void
122GOMP_sections_end (void)
123{
124  gomp_work_share_end ();
125}
126
127void
128GOMP_sections_end_nowait (void)
129{
130  gomp_work_share_end_nowait ();
131}
132