1 /* Copyright (C) 2017-2020 Free Software Foundation, Inc.
2 Contributed by Mentor Embedded.
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 maintenance of threads on AMD GCN. */
27
28 #include "libgomp.h"
29 #include <stdlib.h>
30 #include <string.h>
31
32 static void gomp_thread_start (struct gomp_thread_pool *);
33
34 /* This externally visible function handles target region entry. It
35 sets up a per-team thread pool and transfers control by returning to
36 the kernel in the master thread or gomp_thread_start in other threads.
37
38 The name of this function is part of the interface with the compiler: for
39 each OpenMP kernel the compiler configures the stack, then calls here.
40
41 Likewise, gomp_gcn_exit_kernel is called during the kernel epilogue. */
42
43 void
gomp_gcn_enter_kernel(void)44 gomp_gcn_enter_kernel (void)
45 {
46 int threadid = __builtin_gcn_dim_pos (1);
47
48 if (threadid == 0)
49 {
50 int numthreads = __builtin_gcn_dim_size (1);
51 int teamid = __builtin_gcn_dim_pos(0);
52
53 /* Set up the global state.
54 Every team will do this, but that should be harmless. */
55 gomp_global_icv.nthreads_var = 16;
56 gomp_global_icv.thread_limit_var = numthreads;
57 /* Starting additional threads is not supported. */
58 gomp_global_icv.dyn_var = true;
59
60 /* Initialize the team arena for optimized memory allocation.
61 The arena has been allocated on the host side, and the address
62 passed in via the kernargs. Each team takes a small slice of it. */
63 register void **kernargs asm("s8");
64 void *team_arena = (kernargs[4] + TEAM_ARENA_SIZE*teamid);
65 void * __lds *arena_start = (void * __lds *)TEAM_ARENA_START;
66 void * __lds *arena_free = (void * __lds *)TEAM_ARENA_FREE;
67 void * __lds *arena_end = (void * __lds *)TEAM_ARENA_END;
68 *arena_start = team_arena;
69 *arena_free = team_arena;
70 *arena_end = team_arena + TEAM_ARENA_SIZE;
71
72 /* Allocate and initialize the team-local-storage data. */
73 struct gomp_thread *thrs = team_malloc_cleared (sizeof (*thrs)
74 * numthreads);
75 set_gcn_thrs (thrs);
76
77 /* Allocate and initialize a pool of threads in the team.
78 The threads are already running, of course, we just need to manage
79 the communication between them. */
80 struct gomp_thread_pool *pool = team_malloc (sizeof (*pool));
81 pool->threads = team_malloc (sizeof (void *) * numthreads);
82 for (int tid = 0; tid < numthreads; tid++)
83 pool->threads[tid] = &thrs[tid];
84 pool->threads_size = numthreads;
85 pool->threads_used = numthreads;
86 pool->threads_busy = 1;
87 pool->last_team = NULL;
88 gomp_simple_barrier_init (&pool->threads_dock, numthreads);
89 thrs->thread_pool = pool;
90
91 asm ("s_barrier" ::: "memory");
92 return; /* Return to kernel. */
93 }
94 else
95 {
96 asm ("s_barrier" ::: "memory");
97 gomp_thread_start (gcn_thrs ()[0].thread_pool);
98 /* gomp_thread_start does not return. */
99 }
100 }
101
102 void
gomp_gcn_exit_kernel(void)103 gomp_gcn_exit_kernel (void)
104 {
105 gomp_free_thread (gcn_thrs ());
106 team_free (gcn_thrs ());
107 }
108
109 /* This function contains the idle loop in which a thread waits
110 to be called up to become part of a team. */
111
112 static void
gomp_thread_start(struct gomp_thread_pool * pool)113 gomp_thread_start (struct gomp_thread_pool *pool)
114 {
115 struct gomp_thread *thr = gomp_thread ();
116
117 gomp_sem_init (&thr->release, 0);
118 thr->thread_pool = pool;
119
120 /* The loop exits only when "fn" is assigned "gomp_free_pool_helper",
121 which contains "s_endpgm", or an infinite no-op loop is
122 suspected (this happens when the thread master crashes). */
123 int nul_limit = 99;
124 do
125 {
126 gomp_simple_barrier_wait (&pool->threads_dock);
127 if (!thr->fn)
128 {
129 if (nul_limit-- > 0)
130 continue;
131 else
132 {
133 const char msg[] = ("team master not responding;"
134 " slave thread aborting");
135 write (2, msg, sizeof (msg)-1);
136 abort();
137 }
138 }
139 thr->fn (thr->data);
140 thr->fn = NULL;
141
142 struct gomp_task *task = thr->task;
143 gomp_team_barrier_wait_final (&thr->ts.team->barrier);
144 gomp_finish_task (task);
145 }
146 while (1);
147 }
148
149 /* Launch a team. */
150
151 void
gomp_team_start(void (* fn)(void *),void * data,unsigned nthreads,unsigned flags,struct gomp_team * team,struct gomp_taskgroup * taskgroup)152 gomp_team_start (void (*fn) (void *), void *data, unsigned nthreads,
153 unsigned flags, struct gomp_team *team,
154 struct gomp_taskgroup *taskgroup)
155 {
156 struct gomp_thread *thr, *nthr;
157 struct gomp_task *task;
158 struct gomp_task_icv *icv;
159 struct gomp_thread_pool *pool;
160 unsigned long nthreads_var;
161
162 thr = gomp_thread ();
163 pool = thr->thread_pool;
164 task = thr->task;
165 icv = task ? &task->icv : &gomp_global_icv;
166
167 /* Always save the previous state, even if this isn't a nested team.
168 In particular, we should save any work share state from an outer
169 orphaned work share construct. */
170 team->prev_ts = thr->ts;
171
172 thr->ts.team = team;
173 thr->ts.team_id = 0;
174 ++thr->ts.level;
175 if (nthreads > 1)
176 ++thr->ts.active_level;
177 thr->ts.work_share = &team->work_shares[0];
178 thr->ts.last_work_share = NULL;
179 thr->ts.single_count = 0;
180 thr->ts.static_trip = 0;
181 thr->task = &team->implicit_task[0];
182 nthreads_var = icv->nthreads_var;
183 gomp_init_task (thr->task, task, icv);
184 team->implicit_task[0].icv.nthreads_var = nthreads_var;
185 team->implicit_task[0].taskgroup = taskgroup;
186
187 if (nthreads == 1)
188 return;
189
190 /* Release existing idle threads. */
191 for (unsigned i = 1; i < nthreads; ++i)
192 {
193 nthr = pool->threads[i];
194 nthr->ts.team = team;
195 nthr->ts.work_share = &team->work_shares[0];
196 nthr->ts.last_work_share = NULL;
197 nthr->ts.team_id = i;
198 nthr->ts.level = team->prev_ts.level + 1;
199 nthr->ts.active_level = thr->ts.active_level;
200 nthr->ts.single_count = 0;
201 nthr->ts.static_trip = 0;
202 nthr->task = &team->implicit_task[i];
203 gomp_init_task (nthr->task, task, icv);
204 team->implicit_task[i].icv.nthreads_var = nthreads_var;
205 team->implicit_task[i].taskgroup = taskgroup;
206 nthr->fn = fn;
207 nthr->data = data;
208 team->ordered_release[i] = &nthr->release;
209 }
210
211 gomp_simple_barrier_wait (&pool->threads_dock);
212 }
213
214 #include "../../team.c"
215