1 /* Copyright (C) 2005-2019 Free Software Foundation, Inc.
2 Contributed by Richard Henderson <rth@redhat.com>.
4 This file is part of the GNU Offloading and Multi Processing Library
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)
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
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.
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/>. */
26 /* This file handles the (bare) PARALLEL construct. */
32 /* Determine the number of threads to be launched for a PARALLEL construct.
33 This algorithm is explicitly described in OpenMP 3.0 section 2.4.1.
34 SPECIFIED is a combination of the NUM_THREADS clause and the IF clause.
35 If the IF clause is false, SPECIFIED is forced to 1. When NUM_THREADS
36 is not present, SPECIFIED is 0. */
39 gomp_resolve_num_threads (unsigned specified
, unsigned count
)
41 struct gomp_thread
*thr
= gomp_thread ();
42 struct gomp_task_icv
*icv
;
43 unsigned threads_requested
, max_num_threads
, num_threads
;
45 struct gomp_thread_pool
*pool
;
47 icv
= gomp_icv (false);
51 else if (thr
->ts
.active_level
>= 1 && !icv
->nest_var
)
53 else if (thr
->ts
.active_level
>= gomp_max_active_levels_var
)
56 /* If NUM_THREADS not specified, use nthreads_var. */
58 threads_requested
= icv
->nthreads_var
;
60 threads_requested
= specified
;
62 max_num_threads
= threads_requested
;
64 /* If dynamic threads are enabled, bound the number of threads
68 unsigned dyn
= gomp_dynamic_max_threads ();
69 if (dyn
< max_num_threads
)
70 max_num_threads
= dyn
;
72 /* Optimization for parallel sections. */
73 if (count
&& count
< max_num_threads
)
74 max_num_threads
= count
;
77 /* UINT_MAX stands for infinity. */
78 if (__builtin_expect (icv
->thread_limit_var
== UINT_MAX
, 1)
79 || max_num_threads
== 1)
80 return max_num_threads
;
82 /* The threads_busy counter lives in thread_pool, if there
83 isn't a thread_pool yet, there must be just one thread
84 in the contention group. If thr->team is NULL, this isn't
85 nested parallel, so there is just one thread in the
86 contention group as well, no need to handle it atomically. */
87 pool
= thr
->thread_pool
;
88 if (thr
->ts
.team
== NULL
|| pool
== NULL
)
90 num_threads
= max_num_threads
;
91 if (num_threads
> icv
->thread_limit_var
)
92 num_threads
= icv
->thread_limit_var
;
94 pool
->threads_busy
= num_threads
;
98 #ifdef HAVE_SYNC_BUILTINS
101 busy
= pool
->threads_busy
;
102 num_threads
= max_num_threads
;
103 if (icv
->thread_limit_var
- busy
+ 1 < num_threads
)
104 num_threads
= icv
->thread_limit_var
- busy
+ 1;
106 while (__sync_val_compare_and_swap (&pool
->threads_busy
,
107 busy
, busy
+ num_threads
- 1)
110 gomp_mutex_lock (&gomp_managed_threads_lock
);
111 num_threads
= max_num_threads
;
112 busy
= pool
->threads_busy
;
113 if (icv
->thread_limit_var
- busy
+ 1 < num_threads
)
114 num_threads
= icv
->thread_limit_var
- busy
+ 1;
115 pool
->threads_busy
+= num_threads
- 1;
116 gomp_mutex_unlock (&gomp_managed_threads_lock
);
123 GOMP_parallel_start (void (*fn
) (void *), void *data
, unsigned num_threads
)
125 num_threads
= gomp_resolve_num_threads (num_threads
, 0);
126 gomp_team_start (fn
, data
, num_threads
, 0, gomp_new_team (num_threads
),
131 GOMP_parallel_end (void)
133 struct gomp_task_icv
*icv
= gomp_icv (false);
134 if (__builtin_expect (icv
->thread_limit_var
!= UINT_MAX
, 0))
136 struct gomp_thread
*thr
= gomp_thread ();
137 struct gomp_team
*team
= thr
->ts
.team
;
138 unsigned int nthreads
= team
? team
->nthreads
: 1;
142 /* If not nested, there is just one thread in the
143 contention group left, no need for atomicity. */
144 if (thr
->ts
.team
== NULL
)
145 thr
->thread_pool
->threads_busy
= 1;
148 #ifdef HAVE_SYNC_BUILTINS
149 __sync_fetch_and_add (&thr
->thread_pool
->threads_busy
,
152 gomp_mutex_lock (&gomp_managed_threads_lock
);
153 thr
->thread_pool
->threads_busy
-= nthreads
- 1;
154 gomp_mutex_unlock (&gomp_managed_threads_lock
);
162 ialias (GOMP_parallel_end
)
165 GOMP_parallel (void (*fn
) (void *), void *data
, unsigned num_threads
,
168 num_threads
= gomp_resolve_num_threads (num_threads
, 0);
169 gomp_team_start (fn
, data
, num_threads
, flags
, gomp_new_team (num_threads
),
172 ialias_call (GOMP_parallel_end
) ();
176 GOMP_parallel_reductions (void (*fn
) (void *), void *data
,
177 unsigned num_threads
, unsigned int flags
)
179 struct gomp_taskgroup
*taskgroup
;
180 num_threads
= gomp_resolve_num_threads (num_threads
, 0);
181 uintptr_t *rdata
= *(uintptr_t **)data
;
182 taskgroup
= gomp_parallel_reduction_register (rdata
, num_threads
);
183 gomp_team_start (fn
, data
, num_threads
, flags
, gomp_new_team (num_threads
),
186 ialias_call (GOMP_parallel_end
) ();
187 gomp_sem_destroy (&taskgroup
->taskgroup_sem
);
193 GOMP_cancellation_point (int which
)
195 if (!gomp_cancel_var
)
198 struct gomp_thread
*thr
= gomp_thread ();
199 struct gomp_team
*team
= thr
->ts
.team
;
200 if (which
& (GOMP_CANCEL_LOOP
| GOMP_CANCEL_SECTIONS
))
204 return team
->work_share_cancelled
!= 0;
206 else if (which
& GOMP_CANCEL_TASKGROUP
)
208 if (thr
->task
->taskgroup
)
210 if (thr
->task
->taskgroup
->cancelled
)
212 if (thr
->task
->taskgroup
->workshare
213 && thr
->task
->taskgroup
->prev
214 && thr
->task
->taskgroup
->prev
->cancelled
)
217 /* FALLTHRU into the GOMP_CANCEL_PARALLEL case,
218 as #pragma omp cancel parallel also cancels all explicit
222 return gomp_team_barrier_cancelled (&team
->barrier
);
225 ialias (GOMP_cancellation_point
)
228 GOMP_cancel (int which
, bool do_cancel
)
230 if (!gomp_cancel_var
)
234 return ialias_call (GOMP_cancellation_point
) (which
);
236 struct gomp_thread
*thr
= gomp_thread ();
237 struct gomp_team
*team
= thr
->ts
.team
;
238 if (which
& (GOMP_CANCEL_LOOP
| GOMP_CANCEL_SECTIONS
))
240 /* In orphaned worksharing region, all we want to cancel
241 is current thread. */
243 team
->work_share_cancelled
= 1;
246 else if (which
& GOMP_CANCEL_TASKGROUP
)
248 if (thr
->task
->taskgroup
)
250 struct gomp_taskgroup
*taskgroup
= thr
->task
->taskgroup
;
251 if (taskgroup
->workshare
&& taskgroup
->prev
)
252 taskgroup
= taskgroup
->prev
;
253 if (!taskgroup
->cancelled
)
255 gomp_mutex_lock (&team
->task_lock
);
256 taskgroup
->cancelled
= true;
257 gomp_mutex_unlock (&team
->task_lock
);
262 team
->team_cancelled
= 1;
263 gomp_team_barrier_cancel (team
);
267 /* The public OpenMP API for thread and team related inquiries. */
270 omp_get_num_threads (void)
272 struct gomp_team
*team
= gomp_thread ()->ts
.team
;
273 return team
? team
->nthreads
: 1;
277 omp_get_thread_num (void)
279 return gomp_thread ()->ts
.team_id
;
282 /* This wasn't right for OpenMP 2.5. Active region used to be non-zero
283 when the IF clause doesn't evaluate to false, starting with OpenMP 3.0
284 it is non-zero with more than one thread in the team. */
287 omp_in_parallel (void)
289 return gomp_thread ()->ts
.active_level
> 0;
295 return gomp_thread ()->ts
.level
;
299 omp_get_ancestor_thread_num (int level
)
301 struct gomp_team_state
*ts
= &gomp_thread ()->ts
;
302 if (level
< 0 || level
> ts
->level
)
304 for (level
= ts
->level
- level
; level
> 0; --level
)
305 ts
= &ts
->team
->prev_ts
;
310 omp_get_team_size (int level
)
312 struct gomp_team_state
*ts
= &gomp_thread ()->ts
;
313 if (level
< 0 || level
> ts
->level
)
315 for (level
= ts
->level
- level
; level
> 0; --level
)
316 ts
= &ts
->team
->prev_ts
;
317 if (ts
->team
== NULL
)
320 return ts
->team
->nthreads
;
324 omp_get_active_level (void)
326 return gomp_thread ()->ts
.active_level
;
329 ialias (omp_get_num_threads
)
330 ialias (omp_get_thread_num
)
331 ialias (omp_in_parallel
)
332 ialias (omp_get_level
)
333 ialias (omp_get_ancestor_thread_num
)
334 ialias (omp_get_team_size
)
335 ialias (omp_get_active_level
)