1
2//===----------------------------------------------------------------------===//
3//
4// The LLVM Compiler Infrastructure
5//
6// This file is dual licensed under the MIT and the University of Illinois Open
7// Source Licenses. See LICENSE.txt for details.
8//
9//===----------------------------------------------------------------------===//
10
11#include "kmp.h"
12#include "kmp_i18n.h"
13#include "kmp_io.h"
14#include "kmp_str.h"
15#if OMPT_SUPPORT
16#include "ompt-specific.h"
17#endif
18
19#if OMP_40_ENABLED
20
21/*!
22@ingroup CANCELLATION
23@param loc_ref location of the original task directive
24@param gtid Global thread ID of encountering thread
25@param cncl_kind Cancellation kind (parallel, for, sections, taskgroup)
26
27@return returns true if the cancellation request has been activated and the
28execution thread needs to proceed to the end of the canceled region.
29
30Request cancellation of the binding OpenMP region.
31*/
32kmp_int32 __kmpc_cancel(ident_t *loc_ref, kmp_int32 gtid, kmp_int32 cncl_kind) {
33 kmp_info_t *this_thr = __kmp_threads[gtid];
34
35 KC_TRACE(10, ("__kmpc_cancel: T#%d request %d OMP_CANCELLATION=%d\n", gtid,
36 cncl_kind, __kmp_omp_cancellation));
37
38 KMP_DEBUG_ASSERT(cncl_kind != cancel_noreq);
39 KMP_DEBUG_ASSERT(cncl_kind == cancel_parallel || cncl_kind == cancel_loop ||
40 cncl_kind == cancel_sections ||
41 cncl_kind == cancel_taskgroup);
42 KMP_DEBUG_ASSERT(__kmp_get_gtid() == gtid);
43
44 if (__kmp_omp_cancellation) {
45 switch (cncl_kind) {
46 case cancel_parallel:
47 case cancel_loop:
48 case cancel_sections:
49 // cancellation requests for parallel and worksharing constructs
50 // are handled through the team structure
51 {
52 kmp_team_t *this_team = this_thr->th.th_team;
53 KMP_DEBUG_ASSERT(this_team);
54 kmp_int32 old = cancel_noreq;
55 this_team->t.t_cancel_request.compare_exchange_strong(old, cncl_kind);
56 if (old == cancel_noreq || old == cncl_kind) {
57// we do not have a cancellation request in this team or we do have
58// one that matches the current request -> cancel
59#if OMPT_SUPPORT && OMPT_OPTIONAL
60 if (ompt_enabled.ompt_callback_cancel) {
61 ompt_data_t *task_data;
62 __ompt_get_task_info_internal(0, NULL, &task_data, NULL, NULL,
63 NULL);
64 ompt_cancel_flag_t type = ompt_cancel_parallel;
65 if (cncl_kind == cancel_parallel)
66 type = ompt_cancel_parallel;
67 else if (cncl_kind == cancel_loop)
68 type = ompt_cancel_loop;
69 else if (cncl_kind == cancel_sections)
70 type = ompt_cancel_sections;
71 ompt_callbacks.ompt_callback(ompt_callback_cancel)(
72 task_data, type | ompt_cancel_activated,
73 OMPT_GET_RETURN_ADDRESS(0));
74 }
75#endif
76 return 1 /* true */;
77 }
78 break;
79 }
80 case cancel_taskgroup:
81 // cancellation requests for a task group
82 // are handled through the taskgroup structure
83 {
84 kmp_taskdata_t *task;
85 kmp_taskgroup_t *taskgroup;
86
87 task = this_thr->th.th_current_task;
88 KMP_DEBUG_ASSERT(task);
89
90 taskgroup = task->td_taskgroup;
91 if (taskgroup) {
92 kmp_int32 old = cancel_noreq;
93 taskgroup->cancel_request.compare_exchange_strong(old, cncl_kind);
94 if (old == cancel_noreq || old == cncl_kind) {
95// we do not have a cancellation request in this taskgroup or we do
96// have one that matches the current request -> cancel
97#if OMPT_SUPPORT && OMPT_OPTIONAL
98 if (ompt_enabled.ompt_callback_cancel) {
99 ompt_data_t *task_data;
100 __ompt_get_task_info_internal(0, NULL, &task_data, NULL, NULL,
101 NULL);
102 ompt_callbacks.ompt_callback(ompt_callback_cancel)(
103 task_data, ompt_cancel_taskgroup | ompt_cancel_activated,
104 OMPT_GET_RETURN_ADDRESS(0));
105 }
106#endif
107 return 1 /* true */;
108 }
109 } else {
110 // TODO: what needs to happen here?
111 // the specification disallows cancellation w/o taskgroups
112 // so we might do anything here, let's abort for now
113 KMP_ASSERT(0 /* false */);
114 }
115 }
116 break;
117 default:
118 KMP_ASSERT(0 /* false */);
119 }
120 }
121
122 // ICV OMP_CANCELLATION=false, so we ignored this cancel request
123 KMP_DEBUG_ASSERT(!__kmp_omp_cancellation);
124 return 0 /* false */;
125}
126
127/*!
128@ingroup CANCELLATION
129@param loc_ref location of the original task directive
130@param gtid Global thread ID of encountering thread
131@param cncl_kind Cancellation kind (parallel, for, sections, taskgroup)
132
133@return returns true if a matching cancellation request has been flagged in the
134RTL and the encountering thread has to cancel..
135
136Cancellation point for the encountering thread.
137*/
138kmp_int32 __kmpc_cancellationpoint(ident_t *loc_ref, kmp_int32 gtid,
139 kmp_int32 cncl_kind) {
140 kmp_info_t *this_thr = __kmp_threads[gtid];
141
142 KC_TRACE(10,
143 ("__kmpc_cancellationpoint: T#%d request %d OMP_CANCELLATION=%d\n",
144 gtid, cncl_kind, __kmp_omp_cancellation));
145
146 KMP_DEBUG_ASSERT(cncl_kind != cancel_noreq);
147 KMP_DEBUG_ASSERT(cncl_kind == cancel_parallel || cncl_kind == cancel_loop ||
148 cncl_kind == cancel_sections ||
149 cncl_kind == cancel_taskgroup);
150 KMP_DEBUG_ASSERT(__kmp_get_gtid() == gtid);
151
152 if (__kmp_omp_cancellation) {
153 switch (cncl_kind) {
154 case cancel_parallel:
155 case cancel_loop:
156 case cancel_sections:
157 // cancellation requests for parallel and worksharing constructs
158 // are handled through the team structure
159 {
160 kmp_team_t *this_team = this_thr->th.th_team;
161 KMP_DEBUG_ASSERT(this_team);
162 if (this_team->t.t_cancel_request) {
163 if (cncl_kind == this_team->t.t_cancel_request) {
164// the request in the team structure matches the type of
165// cancellation point so we can cancel
166#if OMPT_SUPPORT && OMPT_OPTIONAL
167 if (ompt_enabled.ompt_callback_cancel) {
168 ompt_data_t *task_data;
169 __ompt_get_task_info_internal(0, NULL, &task_data, NULL, NULL,
170 NULL);
171 ompt_cancel_flag_t type = ompt_cancel_parallel;
172 if (cncl_kind == cancel_parallel)
173 type = ompt_cancel_parallel;
174 else if (cncl_kind == cancel_loop)
175 type = ompt_cancel_loop;
176 else if (cncl_kind == cancel_sections)
177 type = ompt_cancel_sections;
178 ompt_callbacks.ompt_callback(ompt_callback_cancel)(
179 task_data, type | ompt_cancel_detected,
180 OMPT_GET_RETURN_ADDRESS(0));
181 }
182#endif
183 return 1 /* true */;
184 }
185 KMP_ASSERT(0 /* false */);
186 } else {
187 // we do not have a cancellation request pending, so we just
188 // ignore this cancellation point
189 return 0;
190 }
191 break;
192 }
193 case cancel_taskgroup:
194 // cancellation requests for a task group
195 // are handled through the taskgroup structure
196 {
197 kmp_taskdata_t *task;
198 kmp_taskgroup_t *taskgroup;
199
200 task = this_thr->th.th_current_task;
201 KMP_DEBUG_ASSERT(task);
202
203 taskgroup = task->td_taskgroup;
204 if (taskgroup) {
205// return the current status of cancellation for the taskgroup
206#if OMPT_SUPPORT && OMPT_OPTIONAL
207 if (ompt_enabled.ompt_callback_cancel &&
208 !!taskgroup->cancel_request) {
209 ompt_data_t *task_data;
210 __ompt_get_task_info_internal(0, NULL, &task_data, NULL, NULL,
211 NULL);
212 ompt_callbacks.ompt_callback(ompt_callback_cancel)(
213 task_data, ompt_cancel_taskgroup | ompt_cancel_detected,
214 OMPT_GET_RETURN_ADDRESS(0));
215 }
216#endif
217 return !!taskgroup->cancel_request;
218 } else {
219 // if a cancellation point is encountered by a task that does not
220 // belong to a taskgroup, it is OK to ignore it
221 return 0 /* false */;
222 }
223 }
224 default:
225 KMP_ASSERT(0 /* false */);
226 }
227 }
228
229 // ICV OMP_CANCELLATION=false, so we ignore the cancellation point
230 KMP_DEBUG_ASSERT(!__kmp_omp_cancellation);
231 return 0 /* false */;
232}
233
234/*!
235@ingroup CANCELLATION
236@param loc_ref location of the original task directive
237@param gtid Global thread ID of encountering thread
238
239@return returns true if a matching cancellation request has been flagged in the
240RTL and the encountering thread has to cancel..
241
242Barrier with cancellation point to send threads from the barrier to the
243end of the parallel region. Needs a special code pattern as documented
244in the design document for the cancellation feature.
245*/
246kmp_int32 __kmpc_cancel_barrier(ident_t *loc, kmp_int32 gtid) {
247 int ret = 0 /* false */;
248 kmp_info_t *this_thr = __kmp_threads[gtid];
249 kmp_team_t *this_team = this_thr->th.th_team;
250
251 KMP_DEBUG_ASSERT(__kmp_get_gtid() == gtid);
252
253 // call into the standard barrier
254 __kmpc_barrier(loc, gtid);
255
256 // if cancellation is active, check cancellation flag
257 if (__kmp_omp_cancellation) {
258 // depending on which construct to cancel, check the flag and
259 // reset the flag
260 switch (KMP_ATOMIC_LD_RLX(&(this_team->t.t_cancel_request))) {
261 case cancel_parallel:
262 ret = 1;
263 // ensure that threads have checked the flag, when
264 // leaving the above barrier
265 __kmpc_barrier(loc, gtid);
266 this_team->t.t_cancel_request = cancel_noreq;
267 // the next barrier is the fork/join barrier, which
268 // synchronizes the threads leaving here
269 break;
270 case cancel_loop:
271 case cancel_sections:
272 ret = 1;
273 // ensure that threads have checked the flag, when
274 // leaving the above barrier
275 __kmpc_barrier(loc, gtid);
276 this_team->t.t_cancel_request = cancel_noreq;
277 // synchronize the threads again to make sure we do not have any run-away
278 // threads that cause a race on the cancellation flag
279 __kmpc_barrier(loc, gtid);
280 break;
281 case cancel_taskgroup:
282 // this case should not occur
283 KMP_ASSERT(0 /* false */);
284 break;
285 case cancel_noreq:
286 // do nothing
287 break;
288 default:
289 KMP_ASSERT(0 /* false */);
290 }
291 }
292
293 return ret;
294}
295
296/*!
297@ingroup CANCELLATION
298@param loc_ref location of the original task directive
299@param gtid Global thread ID of encountering thread
300
301@return returns true if a matching cancellation request has been flagged in the
302RTL and the encountering thread has to cancel..
303
304Query function to query the current status of cancellation requests.
305Can be used to implement the following pattern:
306
307if (kmp_get_cancellation_status(kmp_cancel_parallel)) {
308 perform_cleanup();
309 #pragma omp cancellation point parallel
310}
311*/
312int __kmp_get_cancellation_status(int cancel_kind) {
313 if (__kmp_omp_cancellation) {
314 kmp_info_t *this_thr = __kmp_entry_thread();
315
316 switch (cancel_kind) {
317 case cancel_parallel:
318 case cancel_loop:
319 case cancel_sections: {
320 kmp_team_t *this_team = this_thr->th.th_team;
321 return this_team->t.t_cancel_request == cancel_kind;
322 }
323 case cancel_taskgroup: {
324 kmp_taskdata_t *task;
325 kmp_taskgroup_t *taskgroup;
326 task = this_thr->th.th_current_task;
327 taskgroup = task->td_taskgroup;
328 return taskgroup && taskgroup->cancel_request;
329 }
330 }
331 }
332
333 return 0 /* false */;
334}
335
336#endif