1 2 //===----------------------------------------------------------------------===// 3 // 4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 5 // See https://llvm.org/LICENSE.txt for license information. 6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 7 // 8 //===----------------------------------------------------------------------===// 9 10 #include "kmp.h" 11 #include "kmp_i18n.h" 12 #include "kmp_io.h" 13 #include "kmp_str.h" 14 #if OMPT_SUPPORT 15 #include "ompt-specific.h" 16 #endif 17 18 /*! 19 @ingroup CANCELLATION 20 @param loc_ref location of the original task directive 21 @param gtid Global thread ID of encountering thread 22 @param cncl_kind Cancellation kind (parallel, for, sections, taskgroup) 23 24 @return returns true if the cancellation request has been activated and the 25 execution thread needs to proceed to the end of the canceled region. 26 27 Request cancellation of the binding OpenMP region. 28 */ 29 kmp_int32 __kmpc_cancel(ident_t *loc_ref, kmp_int32 gtid, kmp_int32 cncl_kind) { 30 kmp_info_t *this_thr = __kmp_threads[gtid]; 31 32 KC_TRACE(10, ("__kmpc_cancel: T#%d request %d OMP_CANCELLATION=%d\n", gtid, 33 cncl_kind, __kmp_omp_cancellation)); 34 35 KMP_DEBUG_ASSERT(cncl_kind != cancel_noreq); 36 KMP_DEBUG_ASSERT(cncl_kind == cancel_parallel || cncl_kind == cancel_loop || 37 cncl_kind == cancel_sections || 38 cncl_kind == cancel_taskgroup); 39 KMP_DEBUG_ASSERT(__kmp_get_gtid() == gtid); 40 41 if (__kmp_omp_cancellation) { 42 switch (cncl_kind) { 43 case cancel_parallel: 44 case cancel_loop: 45 case cancel_sections: 46 // cancellation requests for parallel and worksharing constructs 47 // are handled through the team structure 48 { 49 kmp_team_t *this_team = this_thr->th.th_team; 50 KMP_DEBUG_ASSERT(this_team); 51 kmp_int32 old = cancel_noreq; 52 this_team->t.t_cancel_request.compare_exchange_strong(old, cncl_kind); 53 if (old == cancel_noreq || old == cncl_kind) { 54 // we do not have a cancellation request in this team or we do have 55 // one that matches the current request -> cancel 56 #if OMPT_SUPPORT && OMPT_OPTIONAL 57 if (ompt_enabled.ompt_callback_cancel) { 58 ompt_data_t *task_data; 59 __ompt_get_task_info_internal(0, NULL, &task_data, NULL, NULL, 60 NULL); 61 ompt_cancel_flag_t type = ompt_cancel_parallel; 62 if (cncl_kind == cancel_parallel) 63 type = ompt_cancel_parallel; 64 else if (cncl_kind == cancel_loop) 65 type = ompt_cancel_loop; 66 else if (cncl_kind == cancel_sections) 67 type = ompt_cancel_sections; 68 ompt_callbacks.ompt_callback(ompt_callback_cancel)( 69 task_data, type | ompt_cancel_activated, 70 OMPT_GET_RETURN_ADDRESS(0)); 71 } 72 #endif // OMPT_SUPPORT && OMPT_OPTIONAL 73 return 1 /* true */; 74 } 75 break; 76 } 77 case cancel_taskgroup: 78 // cancellation requests for a task group 79 // are handled through the taskgroup structure 80 { 81 kmp_taskdata_t *task; 82 kmp_taskgroup_t *taskgroup; 83 84 task = this_thr->th.th_current_task; 85 KMP_DEBUG_ASSERT(task); 86 87 taskgroup = task->td_taskgroup; 88 if (taskgroup) { 89 kmp_int32 old = cancel_noreq; 90 taskgroup->cancel_request.compare_exchange_strong(old, cncl_kind); 91 if (old == cancel_noreq || old == cncl_kind) { 92 // we do not have a cancellation request in this taskgroup or we do 93 // have one that matches the current request -> cancel 94 #if OMPT_SUPPORT && OMPT_OPTIONAL 95 if (ompt_enabled.ompt_callback_cancel) { 96 ompt_data_t *task_data; 97 __ompt_get_task_info_internal(0, NULL, &task_data, NULL, NULL, 98 NULL); 99 ompt_callbacks.ompt_callback(ompt_callback_cancel)( 100 task_data, ompt_cancel_taskgroup | ompt_cancel_activated, 101 OMPT_GET_RETURN_ADDRESS(0)); 102 } 103 #endif 104 return 1 /* true */; 105 } 106 } else { 107 // TODO: what needs to happen here? 108 // the specification disallows cancellation w/o taskgroups 109 // so we might do anything here, let's abort for now 110 KMP_ASSERT(0 /* false */); 111 } 112 } 113 break; 114 default: 115 KMP_ASSERT(0 /* false */); 116 } 117 } 118 119 // ICV OMP_CANCELLATION=false, so we ignored this cancel request 120 KMP_DEBUG_ASSERT(!__kmp_omp_cancellation); 121 return 0 /* false */; 122 } 123 124 /*! 125 @ingroup CANCELLATION 126 @param loc_ref location of the original task directive 127 @param gtid Global thread ID of encountering thread 128 @param cncl_kind Cancellation kind (parallel, for, sections, taskgroup) 129 130 @return returns true if a matching cancellation request has been flagged in the 131 RTL and the encountering thread has to cancel.. 132 133 Cancellation point for the encountering thread. 134 */ 135 kmp_int32 __kmpc_cancellationpoint(ident_t *loc_ref, kmp_int32 gtid, 136 kmp_int32 cncl_kind) { 137 kmp_info_t *this_thr = __kmp_threads[gtid]; 138 139 KC_TRACE(10, 140 ("__kmpc_cancellationpoint: T#%d request %d OMP_CANCELLATION=%d\n", 141 gtid, cncl_kind, __kmp_omp_cancellation)); 142 143 KMP_DEBUG_ASSERT(cncl_kind != cancel_noreq); 144 KMP_DEBUG_ASSERT(cncl_kind == cancel_parallel || cncl_kind == cancel_loop || 145 cncl_kind == cancel_sections || 146 cncl_kind == cancel_taskgroup); 147 KMP_DEBUG_ASSERT(__kmp_get_gtid() == gtid); 148 149 if (__kmp_omp_cancellation) { 150 switch (cncl_kind) { 151 case cancel_parallel: 152 case cancel_loop: 153 case cancel_sections: 154 // cancellation requests for parallel and worksharing constructs 155 // are handled through the team structure 156 { 157 kmp_team_t *this_team = this_thr->th.th_team; 158 KMP_DEBUG_ASSERT(this_team); 159 if (this_team->t.t_cancel_request) { 160 if (cncl_kind == this_team->t.t_cancel_request) { 161 // the request in the team structure matches the type of 162 // cancellation point so we can cancel 163 #if OMPT_SUPPORT && OMPT_OPTIONAL 164 if (ompt_enabled.ompt_callback_cancel) { 165 ompt_data_t *task_data; 166 __ompt_get_task_info_internal(0, NULL, &task_data, NULL, NULL, 167 NULL); 168 ompt_cancel_flag_t type = ompt_cancel_parallel; 169 if (cncl_kind == cancel_parallel) 170 type = ompt_cancel_parallel; 171 else if (cncl_kind == cancel_loop) 172 type = ompt_cancel_loop; 173 else if (cncl_kind == cancel_sections) 174 type = ompt_cancel_sections; 175 ompt_callbacks.ompt_callback(ompt_callback_cancel)( 176 task_data, type | ompt_cancel_detected, 177 OMPT_GET_RETURN_ADDRESS(0)); 178 } 179 #endif 180 return 1 /* true */; 181 } 182 KMP_ASSERT(0 /* false */); 183 } else { 184 // we do not have a cancellation request pending, so we just 185 // ignore this cancellation point 186 return 0; 187 } 188 break; 189 } 190 case cancel_taskgroup: 191 // cancellation requests for a task group 192 // are handled through the taskgroup structure 193 { 194 kmp_taskdata_t *task; 195 kmp_taskgroup_t *taskgroup; 196 197 task = this_thr->th.th_current_task; 198 KMP_DEBUG_ASSERT(task); 199 200 taskgroup = task->td_taskgroup; 201 if (taskgroup) { 202 // return the current status of cancellation for the taskgroup 203 #if OMPT_SUPPORT && OMPT_OPTIONAL 204 if (ompt_enabled.ompt_callback_cancel && 205 !!taskgroup->cancel_request) { 206 ompt_data_t *task_data; 207 __ompt_get_task_info_internal(0, NULL, &task_data, NULL, NULL, 208 NULL); 209 ompt_callbacks.ompt_callback(ompt_callback_cancel)( 210 task_data, ompt_cancel_taskgroup | ompt_cancel_detected, 211 OMPT_GET_RETURN_ADDRESS(0)); 212 } 213 #endif 214 return !!taskgroup->cancel_request; 215 } else { 216 // if a cancellation point is encountered by a task that does not 217 // belong to a taskgroup, it is OK to ignore it 218 return 0 /* false */; 219 } 220 } 221 default: 222 KMP_ASSERT(0 /* false */); 223 } 224 } 225 226 // ICV OMP_CANCELLATION=false, so we ignore the cancellation point 227 KMP_DEBUG_ASSERT(!__kmp_omp_cancellation); 228 return 0 /* false */; 229 } 230 231 /*! 232 @ingroup CANCELLATION 233 @param loc_ref location of the original task directive 234 @param gtid Global thread ID of encountering thread 235 236 @return returns true if a matching cancellation request has been flagged in the 237 RTL and the encountering thread has to cancel.. 238 239 Barrier with cancellation point to send threads from the barrier to the 240 end of the parallel region. Needs a special code pattern as documented 241 in the design document for the cancellation feature. 242 */ 243 kmp_int32 __kmpc_cancel_barrier(ident_t *loc, kmp_int32 gtid) { 244 int ret = 0 /* false */; 245 kmp_info_t *this_thr = __kmp_threads[gtid]; 246 kmp_team_t *this_team = this_thr->th.th_team; 247 248 KMP_DEBUG_ASSERT(__kmp_get_gtid() == gtid); 249 250 // call into the standard barrier 251 __kmpc_barrier(loc, gtid); 252 253 // if cancellation is active, check cancellation flag 254 if (__kmp_omp_cancellation) { 255 // depending on which construct to cancel, check the flag and 256 // reset the flag 257 switch (KMP_ATOMIC_LD_RLX(&(this_team->t.t_cancel_request))) { 258 case cancel_parallel: 259 ret = 1; 260 // ensure that threads have checked the flag, when 261 // leaving the above barrier 262 __kmpc_barrier(loc, gtid); 263 this_team->t.t_cancel_request = cancel_noreq; 264 // the next barrier is the fork/join barrier, which 265 // synchronizes the threads leaving here 266 break; 267 case cancel_loop: 268 case cancel_sections: 269 ret = 1; 270 // ensure that threads have checked the flag, when 271 // leaving the above barrier 272 __kmpc_barrier(loc, gtid); 273 this_team->t.t_cancel_request = cancel_noreq; 274 // synchronize the threads again to make sure we do not have any run-away 275 // threads that cause a race on the cancellation flag 276 __kmpc_barrier(loc, gtid); 277 break; 278 case cancel_taskgroup: 279 // this case should not occur 280 KMP_ASSERT(0 /* false */); 281 break; 282 case cancel_noreq: 283 // do nothing 284 break; 285 default: 286 KMP_ASSERT(0 /* false */); 287 } 288 } 289 290 return ret; 291 } 292 293 /*! 294 @ingroup CANCELLATION 295 @param loc_ref location of the original task directive 296 @param gtid Global thread ID of encountering thread 297 298 @return returns true if a matching cancellation request has been flagged in the 299 RTL and the encountering thread has to cancel.. 300 301 Query function to query the current status of cancellation requests. 302 Can be used to implement the following pattern: 303 304 if (kmp_get_cancellation_status(kmp_cancel_parallel)) { 305 perform_cleanup(); 306 #pragma omp cancellation point parallel 307 } 308 */ 309 int __kmp_get_cancellation_status(int cancel_kind) { 310 if (__kmp_omp_cancellation) { 311 kmp_info_t *this_thr = __kmp_entry_thread(); 312 313 switch (cancel_kind) { 314 case cancel_parallel: 315 case cancel_loop: 316 case cancel_sections: { 317 kmp_team_t *this_team = this_thr->th.th_team; 318 return this_team->t.t_cancel_request == cancel_kind; 319 } 320 case cancel_taskgroup: { 321 kmp_taskdata_t *task; 322 kmp_taskgroup_t *taskgroup; 323 task = this_thr->th.th_current_task; 324 taskgroup = task->td_taskgroup; 325 return taskgroup && taskgroup->cancel_request; 326 } 327 } 328 } 329 330 return 0 /* false */; 331 } 332