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 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 SECTIONS construct.  */
27
28#include "libgomp.h"
29
30
31/* Initialize the given work share construct from the given arguments.  */
32
33static inline void
34gomp_sections_init (struct gomp_work_share *ws, unsigned count)
35{
36  ws->sched = GFS_DYNAMIC;
37  ws->chunk_size = 1;
38  ws->end = count + 1L;
39  ws->incr = 1;
40  ws->next = 1;
41#ifdef HAVE_SYNC_BUILTINS
42  /* Prepare things to make each iteration faster.  */
43  if (sizeof (long) > sizeof (unsigned))
44    ws->mode = 1;
45  else
46    {
47      struct gomp_thread *thr = gomp_thread ();
48      struct gomp_team *team = thr->ts.team;
49      long nthreads = team ? team->nthreads : 1;
50
51      ws->mode = ((nthreads | ws->end)
52		  < 1UL << (sizeof (long) * __CHAR_BIT__ / 2 - 1));
53    }
54#else
55  ws->mode = 0;
56#endif
57}
58
59/* This routine is called when first encountering a sections construct
60   that is not bound directly to a parallel construct.  The first thread
61   that arrives will create the work-share construct; subsequent threads
62   will see the construct exists and allocate work from it.
63
64   COUNT is the number of sections in this construct.
65
66   Returns the 1-based section number for this thread to perform, or 0 if
67   all work was assigned to other threads prior to this thread's arrival.  */
68
69unsigned
70GOMP_sections_start (unsigned count)
71{
72  struct gomp_thread *thr = gomp_thread ();
73  long s, e, ret;
74
75  if (gomp_work_share_start (false))
76    {
77      gomp_sections_init (thr->ts.work_share, count);
78      gomp_work_share_init_done ();
79    }
80
81#ifdef HAVE_SYNC_BUILTINS
82  if (gomp_iter_dynamic_next (&s, &e))
83    ret = s;
84  else
85    ret = 0;
86#else
87  gomp_mutex_lock (&thr->ts.work_share->lock);
88  if (gomp_iter_dynamic_next_locked (&s, &e))
89    ret = s;
90  else
91    ret = 0;
92  gomp_mutex_unlock (&thr->ts.work_share->lock);
93#endif
94
95  return ret;
96}
97
98/* This routine is called when the thread completes processing of the
99   section currently assigned to it.  If the work-share construct is
100   bound directly to a parallel construct, then the construct may have
101   been set up before the parallel.  In which case, this may be the
102   first iteration for the thread.
103
104   Returns the 1-based section number for this thread to perform, or 0 if
105   all work was assigned to other threads prior to this thread's arrival.  */
106
107unsigned
108GOMP_sections_next (void)
109{
110  long s, e, ret;
111
112#ifdef HAVE_SYNC_BUILTINS
113  if (gomp_iter_dynamic_next (&s, &e))
114    ret = s;
115  else
116    ret = 0;
117#else
118  struct gomp_thread *thr = gomp_thread ();
119
120  gomp_mutex_lock (&thr->ts.work_share->lock);
121  if (gomp_iter_dynamic_next_locked (&s, &e))
122    ret = s;
123  else
124    ret = 0;
125  gomp_mutex_unlock (&thr->ts.work_share->lock);
126#endif
127
128  return ret;
129}
130
131/* This routine pre-initializes a work-share construct to avoid one
132   synchronization once we get into the loop.  */
133
134void
135GOMP_parallel_sections_start (void (*fn) (void *), void *data,
136			      unsigned num_threads, unsigned count)
137{
138  struct gomp_team *team;
139
140  num_threads = gomp_resolve_num_threads (num_threads, count);
141  team = gomp_new_team (num_threads);
142  gomp_sections_init (&team->work_shares[0], count);
143  gomp_team_start (fn, data, num_threads, 0, team);
144}
145
146ialias_redirect (GOMP_parallel_end)
147
148void
149GOMP_parallel_sections (void (*fn) (void *), void *data,
150			unsigned num_threads, unsigned count, unsigned flags)
151{
152  struct gomp_team *team;
153
154  num_threads = gomp_resolve_num_threads (num_threads, count);
155  team = gomp_new_team (num_threads);
156  gomp_sections_init (&team->work_shares[0], count);
157  gomp_team_start (fn, data, num_threads, flags, team);
158  fn (data);
159  GOMP_parallel_end ();
160}
161
162/* The GOMP_section_end* routines are called after the thread is told
163   that all sections are complete.  The first two versions synchronize
164   all threads; the nowait version does not.  */
165
166void
167GOMP_sections_end (void)
168{
169  gomp_work_share_end ();
170}
171
172bool
173GOMP_sections_end_cancel (void)
174{
175  return gomp_work_share_end_cancel ();
176}
177
178void
179GOMP_sections_end_nowait (void)
180{
181  gomp_work_share_end_nowait ();
182}
183