1 /*
2  * kmp_tasking.cpp -- OpenMP 3.0 tasking support.
3  */
4 
5 //===----------------------------------------------------------------------===//
6 //
7 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
8 // See https://llvm.org/LICENSE.txt for license information.
9 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "kmp.h"
14 #include "kmp_i18n.h"
15 #include "kmp_itt.h"
16 #include "kmp_stats.h"
17 #include "kmp_wait_release.h"
18 #include "kmp_taskdeps.h"
19 
20 #if OMPT_SUPPORT
21 #include "ompt-specific.h"
22 #endif
23 
24 /* forward declaration */
25 static void __kmp_enable_tasking(kmp_task_team_t *task_team,
26                                  kmp_info_t *this_thr);
27 static void __kmp_alloc_task_deque(kmp_info_t *thread,
28                                    kmp_thread_data_t *thread_data);
29 static int __kmp_realloc_task_threads_data(kmp_info_t *thread,
30                                            kmp_task_team_t *task_team);
31 static void __kmp_bottom_half_finish_proxy(kmp_int32 gtid, kmp_task_t *ptask);
32 
33 #ifdef BUILD_TIED_TASK_STACK
34 
35 //  __kmp_trace_task_stack: print the tied tasks from the task stack in order
36 //  from top do bottom
37 //
38 //  gtid: global thread identifier for thread containing stack
39 //  thread_data: thread data for task team thread containing stack
40 //  threshold: value above which the trace statement triggers
41 //  location: string identifying call site of this function (for trace)
42 static void __kmp_trace_task_stack(kmp_int32 gtid,
43                                    kmp_thread_data_t *thread_data,
44                                    int threshold, char *location) {
45   kmp_task_stack_t *task_stack = &thread_data->td.td_susp_tied_tasks;
46   kmp_taskdata_t **stack_top = task_stack->ts_top;
47   kmp_int32 entries = task_stack->ts_entries;
48   kmp_taskdata_t *tied_task;
49 
50   KA_TRACE(
51       threshold,
52       ("__kmp_trace_task_stack(start): location = %s, gtid = %d, entries = %d, "
53        "first_block = %p, stack_top = %p \n",
54        location, gtid, entries, task_stack->ts_first_block, stack_top));
55 
56   KMP_DEBUG_ASSERT(stack_top != NULL);
57   KMP_DEBUG_ASSERT(entries > 0);
58 
59   while (entries != 0) {
60     KMP_DEBUG_ASSERT(stack_top != &task_stack->ts_first_block.sb_block[0]);
61     // fix up ts_top if we need to pop from previous block
62     if (entries & TASK_STACK_INDEX_MASK == 0) {
63       kmp_stack_block_t *stack_block = (kmp_stack_block_t *)(stack_top);
64 
65       stack_block = stack_block->sb_prev;
66       stack_top = &stack_block->sb_block[TASK_STACK_BLOCK_SIZE];
67     }
68 
69     // finish bookkeeping
70     stack_top--;
71     entries--;
72 
73     tied_task = *stack_top;
74 
75     KMP_DEBUG_ASSERT(tied_task != NULL);
76     KMP_DEBUG_ASSERT(tied_task->td_flags.tasktype == TASK_TIED);
77 
78     KA_TRACE(threshold,
79              ("__kmp_trace_task_stack(%s):             gtid=%d, entry=%d, "
80               "stack_top=%p, tied_task=%p\n",
81               location, gtid, entries, stack_top, tied_task));
82   }
83   KMP_DEBUG_ASSERT(stack_top == &task_stack->ts_first_block.sb_block[0]);
84 
85   KA_TRACE(threshold,
86            ("__kmp_trace_task_stack(exit): location = %s, gtid = %d\n",
87             location, gtid));
88 }
89 
90 //  __kmp_init_task_stack: initialize the task stack for the first time
91 //  after a thread_data structure is created.
92 //  It should not be necessary to do this again (assuming the stack works).
93 //
94 //  gtid: global thread identifier of calling thread
95 //  thread_data: thread data for task team thread containing stack
96 static void __kmp_init_task_stack(kmp_int32 gtid,
97                                   kmp_thread_data_t *thread_data) {
98   kmp_task_stack_t *task_stack = &thread_data->td.td_susp_tied_tasks;
99   kmp_stack_block_t *first_block;
100 
101   // set up the first block of the stack
102   first_block = &task_stack->ts_first_block;
103   task_stack->ts_top = (kmp_taskdata_t **)first_block;
104   memset((void *)first_block, '\0',
105          TASK_STACK_BLOCK_SIZE * sizeof(kmp_taskdata_t *));
106 
107   // initialize the stack to be empty
108   task_stack->ts_entries = TASK_STACK_EMPTY;
109   first_block->sb_next = NULL;
110   first_block->sb_prev = NULL;
111 }
112 
113 //  __kmp_free_task_stack: free the task stack when thread_data is destroyed.
114 //
115 //  gtid: global thread identifier for calling thread
116 //  thread_data: thread info for thread containing stack
117 static void __kmp_free_task_stack(kmp_int32 gtid,
118                                   kmp_thread_data_t *thread_data) {
119   kmp_task_stack_t *task_stack = &thread_data->td.td_susp_tied_tasks;
120   kmp_stack_block_t *stack_block = &task_stack->ts_first_block;
121 
122   KMP_DEBUG_ASSERT(task_stack->ts_entries == TASK_STACK_EMPTY);
123   // free from the second block of the stack
124   while (stack_block != NULL) {
125     kmp_stack_block_t *next_block = (stack_block) ? stack_block->sb_next : NULL;
126 
127     stack_block->sb_next = NULL;
128     stack_block->sb_prev = NULL;
129     if (stack_block != &task_stack->ts_first_block) {
130       __kmp_thread_free(thread,
131                         stack_block); // free the block, if not the first
132     }
133     stack_block = next_block;
134   }
135   // initialize the stack to be empty
136   task_stack->ts_entries = 0;
137   task_stack->ts_top = NULL;
138 }
139 
140 //  __kmp_push_task_stack: Push the tied task onto the task stack.
141 //     Grow the stack if necessary by allocating another block.
142 //
143 //  gtid: global thread identifier for calling thread
144 //  thread: thread info for thread containing stack
145 //  tied_task: the task to push on the stack
146 static void __kmp_push_task_stack(kmp_int32 gtid, kmp_info_t *thread,
147                                   kmp_taskdata_t *tied_task) {
148   // GEH - need to consider what to do if tt_threads_data not allocated yet
149   kmp_thread_data_t *thread_data =
150       &thread->th.th_task_team->tt.tt_threads_data[__kmp_tid_from_gtid(gtid)];
151   kmp_task_stack_t *task_stack = &thread_data->td.td_susp_tied_tasks;
152 
153   if (tied_task->td_flags.team_serial || tied_task->td_flags.tasking_ser) {
154     return; // Don't push anything on stack if team or team tasks are serialized
155   }
156 
157   KMP_DEBUG_ASSERT(tied_task->td_flags.tasktype == TASK_TIED);
158   KMP_DEBUG_ASSERT(task_stack->ts_top != NULL);
159 
160   KA_TRACE(20,
161            ("__kmp_push_task_stack(enter): GTID: %d; THREAD: %p; TASK: %p\n",
162             gtid, thread, tied_task));
163   // Store entry
164   *(task_stack->ts_top) = tied_task;
165 
166   // Do bookkeeping for next push
167   task_stack->ts_top++;
168   task_stack->ts_entries++;
169 
170   if (task_stack->ts_entries & TASK_STACK_INDEX_MASK == 0) {
171     // Find beginning of this task block
172     kmp_stack_block_t *stack_block =
173         (kmp_stack_block_t *)(task_stack->ts_top - TASK_STACK_BLOCK_SIZE);
174 
175     // Check if we already have a block
176     if (stack_block->sb_next !=
177         NULL) { // reset ts_top to beginning of next block
178       task_stack->ts_top = &stack_block->sb_next->sb_block[0];
179     } else { // Alloc new block and link it up
180       kmp_stack_block_t *new_block = (kmp_stack_block_t *)__kmp_thread_calloc(
181           thread, sizeof(kmp_stack_block_t));
182 
183       task_stack->ts_top = &new_block->sb_block[0];
184       stack_block->sb_next = new_block;
185       new_block->sb_prev = stack_block;
186       new_block->sb_next = NULL;
187 
188       KA_TRACE(
189           30,
190           ("__kmp_push_task_stack(): GTID: %d; TASK: %p; Alloc new block: %p\n",
191            gtid, tied_task, new_block));
192     }
193   }
194   KA_TRACE(20, ("__kmp_push_task_stack(exit): GTID: %d; TASK: %p\n", gtid,
195                 tied_task));
196 }
197 
198 //  __kmp_pop_task_stack: Pop the tied task from the task stack.  Don't return
199 //  the task, just check to make sure it matches the ending task passed in.
200 //
201 //  gtid: global thread identifier for the calling thread
202 //  thread: thread info structure containing stack
203 //  tied_task: the task popped off the stack
204 //  ending_task: the task that is ending (should match popped task)
205 static void __kmp_pop_task_stack(kmp_int32 gtid, kmp_info_t *thread,
206                                  kmp_taskdata_t *ending_task) {
207   // GEH - need to consider what to do if tt_threads_data not allocated yet
208   kmp_thread_data_t *thread_data =
209       &thread->th.th_task_team->tt_threads_data[__kmp_tid_from_gtid(gtid)];
210   kmp_task_stack_t *task_stack = &thread_data->td.td_susp_tied_tasks;
211   kmp_taskdata_t *tied_task;
212 
213   if (ending_task->td_flags.team_serial || ending_task->td_flags.tasking_ser) {
214     // Don't pop anything from stack if team or team tasks are serialized
215     return;
216   }
217 
218   KMP_DEBUG_ASSERT(task_stack->ts_top != NULL);
219   KMP_DEBUG_ASSERT(task_stack->ts_entries > 0);
220 
221   KA_TRACE(20, ("__kmp_pop_task_stack(enter): GTID: %d; THREAD: %p\n", gtid,
222                 thread));
223 
224   // fix up ts_top if we need to pop from previous block
225   if (task_stack->ts_entries & TASK_STACK_INDEX_MASK == 0) {
226     kmp_stack_block_t *stack_block = (kmp_stack_block_t *)(task_stack->ts_top);
227 
228     stack_block = stack_block->sb_prev;
229     task_stack->ts_top = &stack_block->sb_block[TASK_STACK_BLOCK_SIZE];
230   }
231 
232   // finish bookkeeping
233   task_stack->ts_top--;
234   task_stack->ts_entries--;
235 
236   tied_task = *(task_stack->ts_top);
237 
238   KMP_DEBUG_ASSERT(tied_task != NULL);
239   KMP_DEBUG_ASSERT(tied_task->td_flags.tasktype == TASK_TIED);
240   KMP_DEBUG_ASSERT(tied_task == ending_task); // If we built the stack correctly
241 
242   KA_TRACE(20, ("__kmp_pop_task_stack(exit): GTID: %d; TASK: %p\n", gtid,
243                 tied_task));
244   return;
245 }
246 #endif /* BUILD_TIED_TASK_STACK */
247 
248 // returns 1 if new task is allowed to execute, 0 otherwise
249 // checks Task Scheduling constraint (if requested) and
250 // mutexinoutset dependencies if any
251 static bool __kmp_task_is_allowed(int gtid, const kmp_int32 is_constrained,
252                                   const kmp_taskdata_t *tasknew,
253                                   const kmp_taskdata_t *taskcurr) {
254   if (is_constrained && (tasknew->td_flags.tiedness == TASK_TIED)) {
255     // Check if the candidate obeys the Task Scheduling Constraints (TSC)
256     // only descendant of all deferred tied tasks can be scheduled, checking
257     // the last one is enough, as it in turn is the descendant of all others
258     kmp_taskdata_t *current = taskcurr->td_last_tied;
259     KMP_DEBUG_ASSERT(current != NULL);
260     // check if the task is not suspended on barrier
261     if (current->td_flags.tasktype == TASK_EXPLICIT ||
262         current->td_taskwait_thread > 0) { // <= 0 on barrier
263       kmp_int32 level = current->td_level;
264       kmp_taskdata_t *parent = tasknew->td_parent;
265       while (parent != current && parent->td_level > level) {
266         // check generation up to the level of the current task
267         parent = parent->td_parent;
268         KMP_DEBUG_ASSERT(parent != NULL);
269       }
270       if (parent != current)
271         return false;
272     }
273   }
274   // Check mutexinoutset dependencies, acquire locks
275   kmp_depnode_t *node = tasknew->td_depnode;
276   if (UNLIKELY(node && (node->dn.mtx_num_locks > 0))) {
277     for (int i = 0; i < node->dn.mtx_num_locks; ++i) {
278       KMP_DEBUG_ASSERT(node->dn.mtx_locks[i] != NULL);
279       if (__kmp_test_lock(node->dn.mtx_locks[i], gtid))
280         continue;
281       // could not get the lock, release previous locks
282       for (int j = i - 1; j >= 0; --j)
283         __kmp_release_lock(node->dn.mtx_locks[j], gtid);
284       return false;
285     }
286     // negative num_locks means all locks acquired successfully
287     node->dn.mtx_num_locks = -node->dn.mtx_num_locks;
288   }
289   return true;
290 }
291 
292 // __kmp_realloc_task_deque:
293 // Re-allocates a task deque for a particular thread, copies the content from
294 // the old deque and adjusts the necessary data structures relating to the
295 // deque. This operation must be done with the deque_lock being held
296 static void __kmp_realloc_task_deque(kmp_info_t *thread,
297                                      kmp_thread_data_t *thread_data) {
298   kmp_int32 size = TASK_DEQUE_SIZE(thread_data->td);
299   KMP_DEBUG_ASSERT(TCR_4(thread_data->td.td_deque_ntasks) == size);
300   kmp_int32 new_size = 2 * size;
301 
302   KE_TRACE(10, ("__kmp_realloc_task_deque: T#%d reallocating deque[from %d to "
303                 "%d] for thread_data %p\n",
304                 __kmp_gtid_from_thread(thread), size, new_size, thread_data));
305 
306   kmp_taskdata_t **new_deque =
307       (kmp_taskdata_t **)__kmp_allocate(new_size * sizeof(kmp_taskdata_t *));
308 
309   int i, j;
310   for (i = thread_data->td.td_deque_head, j = 0; j < size;
311        i = (i + 1) & TASK_DEQUE_MASK(thread_data->td), j++)
312     new_deque[j] = thread_data->td.td_deque[i];
313 
314   __kmp_free(thread_data->td.td_deque);
315 
316   thread_data->td.td_deque_head = 0;
317   thread_data->td.td_deque_tail = size;
318   thread_data->td.td_deque = new_deque;
319   thread_data->td.td_deque_size = new_size;
320 }
321 
322 static kmp_task_pri_t *__kmp_alloc_task_pri_list() {
323   kmp_task_pri_t *l = (kmp_task_pri_t *)__kmp_allocate(sizeof(kmp_task_pri_t));
324   kmp_thread_data_t *thread_data = &l->td;
325   __kmp_init_bootstrap_lock(&thread_data->td.td_deque_lock);
326   thread_data->td.td_deque_last_stolen = -1;
327   KE_TRACE(20, ("__kmp_alloc_task_pri_list: T#%d allocating deque[%d] "
328                 "for thread_data %p\n",
329                 __kmp_get_gtid(), INITIAL_TASK_DEQUE_SIZE, thread_data));
330   thread_data->td.td_deque = (kmp_taskdata_t **)__kmp_allocate(
331       INITIAL_TASK_DEQUE_SIZE * sizeof(kmp_taskdata_t *));
332   thread_data->td.td_deque_size = INITIAL_TASK_DEQUE_SIZE;
333   return l;
334 }
335 
336 // The function finds the deque of priority tasks with given priority, or
337 // allocates a new deque and put it into sorted (high -> low) list of deques.
338 // Deques of non-default priority tasks are shared between all threads in team,
339 // as opposed to per-thread deques of tasks with default priority.
340 // The function is called under the lock task_team->tt.tt_task_pri_lock.
341 static kmp_thread_data_t *
342 __kmp_get_priority_deque_data(kmp_task_team_t *task_team, kmp_int32 pri) {
343   kmp_thread_data_t *thread_data;
344   kmp_task_pri_t *lst = task_team->tt.tt_task_pri_list;
345   if (lst->priority == pri) {
346     // Found queue of tasks with given priority.
347     thread_data = &lst->td;
348   } else if (lst->priority < pri) {
349     // All current priority queues contain tasks with lower priority.
350     // Allocate new one for given priority tasks.
351     kmp_task_pri_t *list = __kmp_alloc_task_pri_list();
352     thread_data = &list->td;
353     list->priority = pri;
354     list->next = lst;
355     task_team->tt.tt_task_pri_list = list;
356   } else { // task_team->tt.tt_task_pri_list->priority > pri
357     kmp_task_pri_t *next_queue = lst->next;
358     while (next_queue && next_queue->priority > pri) {
359       lst = next_queue;
360       next_queue = lst->next;
361     }
362     // lst->priority > pri && (next == NULL || pri >= next->priority)
363     if (next_queue == NULL) {
364       // No queue with pri priority, need to allocate new one.
365       kmp_task_pri_t *list = __kmp_alloc_task_pri_list();
366       thread_data = &list->td;
367       list->priority = pri;
368       list->next = NULL;
369       lst->next = list;
370     } else if (next_queue->priority == pri) {
371       // Found queue of tasks with given priority.
372       thread_data = &next_queue->td;
373     } else { // lst->priority > pri > next->priority
374       // insert newly allocated between existed queues
375       kmp_task_pri_t *list = __kmp_alloc_task_pri_list();
376       thread_data = &list->td;
377       list->priority = pri;
378       list->next = next_queue;
379       lst->next = list;
380     }
381   }
382   return thread_data;
383 }
384 
385 //  __kmp_push_priority_task: Add a task to the team's priority task deque
386 static kmp_int32 __kmp_push_priority_task(kmp_int32 gtid, kmp_info_t *thread,
387                                           kmp_taskdata_t *taskdata,
388                                           kmp_task_team_t *task_team,
389                                           kmp_int32 pri) {
390   kmp_thread_data_t *thread_data = NULL;
391   KA_TRACE(20,
392            ("__kmp_push_priority_task: T#%d trying to push task %p, pri %d.\n",
393             gtid, taskdata, pri));
394 
395   // Find task queue specific to priority value
396   kmp_task_pri_t *lst = task_team->tt.tt_task_pri_list;
397   if (UNLIKELY(lst == NULL)) {
398     __kmp_acquire_bootstrap_lock(&task_team->tt.tt_task_pri_lock);
399     if (task_team->tt.tt_task_pri_list == NULL) {
400       // List of queues is still empty, allocate one.
401       kmp_task_pri_t *list = __kmp_alloc_task_pri_list();
402       thread_data = &list->td;
403       list->priority = pri;
404       list->next = NULL;
405       task_team->tt.tt_task_pri_list = list;
406     } else {
407       // Other thread initialized a queue. Check if it fits and get thread_data.
408       thread_data = __kmp_get_priority_deque_data(task_team, pri);
409     }
410     __kmp_release_bootstrap_lock(&task_team->tt.tt_task_pri_lock);
411   } else {
412     if (lst->priority == pri) {
413       // Found queue of tasks with given priority.
414       thread_data = &lst->td;
415     } else {
416       __kmp_acquire_bootstrap_lock(&task_team->tt.tt_task_pri_lock);
417       thread_data = __kmp_get_priority_deque_data(task_team, pri);
418       __kmp_release_bootstrap_lock(&task_team->tt.tt_task_pri_lock);
419     }
420   }
421   KMP_DEBUG_ASSERT(thread_data);
422 
423   __kmp_acquire_bootstrap_lock(&thread_data->td.td_deque_lock);
424   // Check if deque is full
425   if (TCR_4(thread_data->td.td_deque_ntasks) >=
426       TASK_DEQUE_SIZE(thread_data->td)) {
427     if (__kmp_enable_task_throttling &&
428         __kmp_task_is_allowed(gtid, __kmp_task_stealing_constraint, taskdata,
429                               thread->th.th_current_task)) {
430       __kmp_release_bootstrap_lock(&thread_data->td.td_deque_lock);
431       KA_TRACE(20, ("__kmp_push_priority_task: T#%d deque is full; returning "
432                     "TASK_NOT_PUSHED for task %p\n",
433                     gtid, taskdata));
434       return TASK_NOT_PUSHED;
435     } else {
436       // expand deque to push the task which is not allowed to execute
437       __kmp_realloc_task_deque(thread, thread_data);
438     }
439   }
440   KMP_DEBUG_ASSERT(TCR_4(thread_data->td.td_deque_ntasks) <
441                    TASK_DEQUE_SIZE(thread_data->td));
442   // Push taskdata.
443   thread_data->td.td_deque[thread_data->td.td_deque_tail] = taskdata;
444   // Wrap index.
445   thread_data->td.td_deque_tail =
446       (thread_data->td.td_deque_tail + 1) & TASK_DEQUE_MASK(thread_data->td);
447   TCW_4(thread_data->td.td_deque_ntasks,
448         TCR_4(thread_data->td.td_deque_ntasks) + 1); // Adjust task count
449   KMP_FSYNC_RELEASING(thread->th.th_current_task); // releasing self
450   KMP_FSYNC_RELEASING(taskdata); // releasing child
451   KA_TRACE(20, ("__kmp_push_priority_task: T#%d returning "
452                 "TASK_SUCCESSFULLY_PUSHED: task=%p ntasks=%d head=%u tail=%u\n",
453                 gtid, taskdata, thread_data->td.td_deque_ntasks,
454                 thread_data->td.td_deque_head, thread_data->td.td_deque_tail));
455   __kmp_release_bootstrap_lock(&thread_data->td.td_deque_lock);
456   task_team->tt.tt_num_task_pri++; // atomic inc
457   return TASK_SUCCESSFULLY_PUSHED;
458 }
459 
460 //  __kmp_push_task: Add a task to the thread's deque
461 static kmp_int32 __kmp_push_task(kmp_int32 gtid, kmp_task_t *task) {
462   kmp_info_t *thread = __kmp_threads[gtid];
463   kmp_taskdata_t *taskdata = KMP_TASK_TO_TASKDATA(task);
464 
465   // If we encounter a hidden helper task, and the current thread is not a
466   // hidden helper thread, we have to give the task to any hidden helper thread
467   // starting from its shadow one.
468   if (UNLIKELY(taskdata->td_flags.hidden_helper &&
469                !KMP_HIDDEN_HELPER_THREAD(gtid))) {
470     kmp_int32 shadow_gtid = KMP_GTID_TO_SHADOW_GTID(gtid);
471     __kmpc_give_task(task, __kmp_tid_from_gtid(shadow_gtid));
472     // Signal the hidden helper threads.
473     __kmp_hidden_helper_worker_thread_signal();
474     return TASK_SUCCESSFULLY_PUSHED;
475   }
476 
477   kmp_task_team_t *task_team = thread->th.th_task_team;
478   kmp_int32 tid = __kmp_tid_from_gtid(gtid);
479   kmp_thread_data_t *thread_data;
480 
481   KA_TRACE(20,
482            ("__kmp_push_task: T#%d trying to push task %p.\n", gtid, taskdata));
483 
484   if (UNLIKELY(taskdata->td_flags.tiedness == TASK_UNTIED)) {
485     // untied task needs to increment counter so that the task structure is not
486     // freed prematurely
487     kmp_int32 counter = 1 + KMP_ATOMIC_INC(&taskdata->td_untied_count);
488     KMP_DEBUG_USE_VAR(counter);
489     KA_TRACE(
490         20,
491         ("__kmp_push_task: T#%d untied_count (%d) incremented for task %p\n",
492          gtid, counter, taskdata));
493   }
494 
495   // The first check avoids building task_team thread data if serialized
496   if (UNLIKELY(taskdata->td_flags.task_serial)) {
497     KA_TRACE(20, ("__kmp_push_task: T#%d team serialized; returning "
498                   "TASK_NOT_PUSHED for task %p\n",
499                   gtid, taskdata));
500     return TASK_NOT_PUSHED;
501   }
502 
503   // Now that serialized tasks have returned, we can assume that we are not in
504   // immediate exec mode
505   KMP_DEBUG_ASSERT(__kmp_tasking_mode != tskm_immediate_exec);
506   if (UNLIKELY(!KMP_TASKING_ENABLED(task_team))) {
507     __kmp_enable_tasking(task_team, thread);
508   }
509   KMP_DEBUG_ASSERT(TCR_4(task_team->tt.tt_found_tasks) == TRUE);
510   KMP_DEBUG_ASSERT(TCR_PTR(task_team->tt.tt_threads_data) != NULL);
511 
512   if (taskdata->td_flags.priority_specified && task->data2.priority > 0 &&
513       __kmp_max_task_priority > 0) {
514     int pri = KMP_MIN(task->data2.priority, __kmp_max_task_priority);
515     return __kmp_push_priority_task(gtid, thread, taskdata, task_team, pri);
516   }
517 
518   // Find tasking deque specific to encountering thread
519   thread_data = &task_team->tt.tt_threads_data[tid];
520 
521   // No lock needed since only owner can allocate. If the task is hidden_helper,
522   // we don't need it either because we have initialized the dequeue for hidden
523   // helper thread data.
524   if (UNLIKELY(thread_data->td.td_deque == NULL)) {
525     __kmp_alloc_task_deque(thread, thread_data);
526   }
527 
528   int locked = 0;
529   // Check if deque is full
530   if (TCR_4(thread_data->td.td_deque_ntasks) >=
531       TASK_DEQUE_SIZE(thread_data->td)) {
532     if (__kmp_enable_task_throttling &&
533         __kmp_task_is_allowed(gtid, __kmp_task_stealing_constraint, taskdata,
534                               thread->th.th_current_task)) {
535       KA_TRACE(20, ("__kmp_push_task: T#%d deque is full; returning "
536                     "TASK_NOT_PUSHED for task %p\n",
537                     gtid, taskdata));
538       return TASK_NOT_PUSHED;
539     } else {
540       __kmp_acquire_bootstrap_lock(&thread_data->td.td_deque_lock);
541       locked = 1;
542       if (TCR_4(thread_data->td.td_deque_ntasks) >=
543           TASK_DEQUE_SIZE(thread_data->td)) {
544         // expand deque to push the task which is not allowed to execute
545         __kmp_realloc_task_deque(thread, thread_data);
546       }
547     }
548   }
549   // Lock the deque for the task push operation
550   if (!locked) {
551     __kmp_acquire_bootstrap_lock(&thread_data->td.td_deque_lock);
552     // Need to recheck as we can get a proxy task from thread outside of OpenMP
553     if (TCR_4(thread_data->td.td_deque_ntasks) >=
554         TASK_DEQUE_SIZE(thread_data->td)) {
555       if (__kmp_enable_task_throttling &&
556           __kmp_task_is_allowed(gtid, __kmp_task_stealing_constraint, taskdata,
557                                 thread->th.th_current_task)) {
558         __kmp_release_bootstrap_lock(&thread_data->td.td_deque_lock);
559         KA_TRACE(20, ("__kmp_push_task: T#%d deque is full on 2nd check; "
560                       "returning TASK_NOT_PUSHED for task %p\n",
561                       gtid, taskdata));
562         return TASK_NOT_PUSHED;
563       } else {
564         // expand deque to push the task which is not allowed to execute
565         __kmp_realloc_task_deque(thread, thread_data);
566       }
567     }
568   }
569   // Must have room since no thread can add tasks but calling thread
570   KMP_DEBUG_ASSERT(TCR_4(thread_data->td.td_deque_ntasks) <
571                    TASK_DEQUE_SIZE(thread_data->td));
572 
573   thread_data->td.td_deque[thread_data->td.td_deque_tail] =
574       taskdata; // Push taskdata
575   // Wrap index.
576   thread_data->td.td_deque_tail =
577       (thread_data->td.td_deque_tail + 1) & TASK_DEQUE_MASK(thread_data->td);
578   TCW_4(thread_data->td.td_deque_ntasks,
579         TCR_4(thread_data->td.td_deque_ntasks) + 1); // Adjust task count
580   KMP_FSYNC_RELEASING(thread->th.th_current_task); // releasing self
581   KMP_FSYNC_RELEASING(taskdata); // releasing child
582   KA_TRACE(20, ("__kmp_push_task: T#%d returning TASK_SUCCESSFULLY_PUSHED: "
583                 "task=%p ntasks=%d head=%u tail=%u\n",
584                 gtid, taskdata, thread_data->td.td_deque_ntasks,
585                 thread_data->td.td_deque_head, thread_data->td.td_deque_tail));
586 
587   __kmp_release_bootstrap_lock(&thread_data->td.td_deque_lock);
588 
589   return TASK_SUCCESSFULLY_PUSHED;
590 }
591 
592 // __kmp_pop_current_task_from_thread: set up current task from called thread
593 // when team ends
594 //
595 // this_thr: thread structure to set current_task in.
596 void __kmp_pop_current_task_from_thread(kmp_info_t *this_thr) {
597   KF_TRACE(10, ("__kmp_pop_current_task_from_thread(enter): T#%d "
598                 "this_thread=%p, curtask=%p, "
599                 "curtask_parent=%p\n",
600                 0, this_thr, this_thr->th.th_current_task,
601                 this_thr->th.th_current_task->td_parent));
602 
603   this_thr->th.th_current_task = this_thr->th.th_current_task->td_parent;
604 
605   KF_TRACE(10, ("__kmp_pop_current_task_from_thread(exit): T#%d "
606                 "this_thread=%p, curtask=%p, "
607                 "curtask_parent=%p\n",
608                 0, this_thr, this_thr->th.th_current_task,
609                 this_thr->th.th_current_task->td_parent));
610 }
611 
612 // __kmp_push_current_task_to_thread: set up current task in called thread for a
613 // new team
614 //
615 // this_thr: thread structure to set up
616 // team: team for implicit task data
617 // tid: thread within team to set up
618 void __kmp_push_current_task_to_thread(kmp_info_t *this_thr, kmp_team_t *team,
619                                        int tid) {
620   // current task of the thread is a parent of the new just created implicit
621   // tasks of new team
622   KF_TRACE(10, ("__kmp_push_current_task_to_thread(enter): T#%d this_thread=%p "
623                 "curtask=%p "
624                 "parent_task=%p\n",
625                 tid, this_thr, this_thr->th.th_current_task,
626                 team->t.t_implicit_task_taskdata[tid].td_parent));
627 
628   KMP_DEBUG_ASSERT(this_thr != NULL);
629 
630   if (tid == 0) {
631     if (this_thr->th.th_current_task != &team->t.t_implicit_task_taskdata[0]) {
632       team->t.t_implicit_task_taskdata[0].td_parent =
633           this_thr->th.th_current_task;
634       this_thr->th.th_current_task = &team->t.t_implicit_task_taskdata[0];
635     }
636   } else {
637     team->t.t_implicit_task_taskdata[tid].td_parent =
638         team->t.t_implicit_task_taskdata[0].td_parent;
639     this_thr->th.th_current_task = &team->t.t_implicit_task_taskdata[tid];
640   }
641 
642   KF_TRACE(10, ("__kmp_push_current_task_to_thread(exit): T#%d this_thread=%p "
643                 "curtask=%p "
644                 "parent_task=%p\n",
645                 tid, this_thr, this_thr->th.th_current_task,
646                 team->t.t_implicit_task_taskdata[tid].td_parent));
647 }
648 
649 // __kmp_task_start: bookkeeping for a task starting execution
650 //
651 // GTID: global thread id of calling thread
652 // task: task starting execution
653 // current_task: task suspending
654 static void __kmp_task_start(kmp_int32 gtid, kmp_task_t *task,
655                              kmp_taskdata_t *current_task) {
656   kmp_taskdata_t *taskdata = KMP_TASK_TO_TASKDATA(task);
657   kmp_info_t *thread = __kmp_threads[gtid];
658 
659   KA_TRACE(10,
660            ("__kmp_task_start(enter): T#%d starting task %p: current_task=%p\n",
661             gtid, taskdata, current_task));
662 
663   KMP_DEBUG_ASSERT(taskdata->td_flags.tasktype == TASK_EXPLICIT);
664 
665   // mark currently executing task as suspended
666   // TODO: GEH - make sure root team implicit task is initialized properly.
667   // KMP_DEBUG_ASSERT( current_task -> td_flags.executing == 1 );
668   current_task->td_flags.executing = 0;
669 
670 // Add task to stack if tied
671 #ifdef BUILD_TIED_TASK_STACK
672   if (taskdata->td_flags.tiedness == TASK_TIED) {
673     __kmp_push_task_stack(gtid, thread, taskdata);
674   }
675 #endif /* BUILD_TIED_TASK_STACK */
676 
677   // mark starting task as executing and as current task
678   thread->th.th_current_task = taskdata;
679 
680   KMP_DEBUG_ASSERT(taskdata->td_flags.started == 0 ||
681                    taskdata->td_flags.tiedness == TASK_UNTIED);
682   KMP_DEBUG_ASSERT(taskdata->td_flags.executing == 0 ||
683                    taskdata->td_flags.tiedness == TASK_UNTIED);
684   taskdata->td_flags.started = 1;
685   taskdata->td_flags.executing = 1;
686   KMP_DEBUG_ASSERT(taskdata->td_flags.complete == 0);
687   KMP_DEBUG_ASSERT(taskdata->td_flags.freed == 0);
688 
689   // GEH TODO: shouldn't we pass some sort of location identifier here?
690   // APT: yes, we will pass location here.
691   // need to store current thread state (in a thread or taskdata structure)
692   // before setting work_state, otherwise wrong state is set after end of task
693 
694   KA_TRACE(10, ("__kmp_task_start(exit): T#%d task=%p\n", gtid, taskdata));
695 
696   return;
697 }
698 
699 #if OMPT_SUPPORT
700 //------------------------------------------------------------------------------
701 // __ompt_task_init:
702 //   Initialize OMPT fields maintained by a task. This will only be called after
703 //   ompt_start_tool, so we already know whether ompt is enabled or not.
704 
705 static inline void __ompt_task_init(kmp_taskdata_t *task, int tid) {
706   // The calls to __ompt_task_init already have the ompt_enabled condition.
707   task->ompt_task_info.task_data.value = 0;
708   task->ompt_task_info.frame.exit_frame = ompt_data_none;
709   task->ompt_task_info.frame.enter_frame = ompt_data_none;
710   task->ompt_task_info.frame.exit_frame_flags =
711       ompt_frame_runtime | ompt_frame_framepointer;
712   task->ompt_task_info.frame.enter_frame_flags =
713       ompt_frame_runtime | ompt_frame_framepointer;
714 }
715 
716 // __ompt_task_start:
717 //   Build and trigger task-begin event
718 static inline void __ompt_task_start(kmp_task_t *task,
719                                      kmp_taskdata_t *current_task,
720                                      kmp_int32 gtid) {
721   kmp_taskdata_t *taskdata = KMP_TASK_TO_TASKDATA(task);
722   ompt_task_status_t status = ompt_task_switch;
723   if (__kmp_threads[gtid]->th.ompt_thread_info.ompt_task_yielded) {
724     status = ompt_task_yield;
725     __kmp_threads[gtid]->th.ompt_thread_info.ompt_task_yielded = 0;
726   }
727   /* let OMPT know that we're about to run this task */
728   if (ompt_enabled.ompt_callback_task_schedule) {
729     ompt_callbacks.ompt_callback(ompt_callback_task_schedule)(
730         &(current_task->ompt_task_info.task_data), status,
731         &(taskdata->ompt_task_info.task_data));
732   }
733   taskdata->ompt_task_info.scheduling_parent = current_task;
734 }
735 
736 // __ompt_task_finish:
737 //   Build and trigger final task-schedule event
738 static inline void __ompt_task_finish(kmp_task_t *task,
739                                       kmp_taskdata_t *resumed_task,
740                                       ompt_task_status_t status) {
741   if (ompt_enabled.ompt_callback_task_schedule) {
742     kmp_taskdata_t *taskdata = KMP_TASK_TO_TASKDATA(task);
743     if (__kmp_omp_cancellation && taskdata->td_taskgroup &&
744         taskdata->td_taskgroup->cancel_request == cancel_taskgroup) {
745       status = ompt_task_cancel;
746     }
747 
748     /* let OMPT know that we're returning to the callee task */
749     ompt_callbacks.ompt_callback(ompt_callback_task_schedule)(
750         &(taskdata->ompt_task_info.task_data), status,
751         (resumed_task ? &(resumed_task->ompt_task_info.task_data) : NULL));
752   }
753 }
754 #endif
755 
756 template <bool ompt>
757 static void __kmpc_omp_task_begin_if0_template(ident_t *loc_ref, kmp_int32 gtid,
758                                                kmp_task_t *task,
759                                                void *frame_address,
760                                                void *return_address) {
761   kmp_taskdata_t *taskdata = KMP_TASK_TO_TASKDATA(task);
762   kmp_taskdata_t *current_task = __kmp_threads[gtid]->th.th_current_task;
763 
764   KA_TRACE(10, ("__kmpc_omp_task_begin_if0(enter): T#%d loc=%p task=%p "
765                 "current_task=%p\n",
766                 gtid, loc_ref, taskdata, current_task));
767 
768   if (UNLIKELY(taskdata->td_flags.tiedness == TASK_UNTIED)) {
769     // untied task needs to increment counter so that the task structure is not
770     // freed prematurely
771     kmp_int32 counter = 1 + KMP_ATOMIC_INC(&taskdata->td_untied_count);
772     KMP_DEBUG_USE_VAR(counter);
773     KA_TRACE(20, ("__kmpc_omp_task_begin_if0: T#%d untied_count (%d) "
774                   "incremented for task %p\n",
775                   gtid, counter, taskdata));
776   }
777 
778   taskdata->td_flags.task_serial =
779       1; // Execute this task immediately, not deferred.
780   __kmp_task_start(gtid, task, current_task);
781 
782 #if OMPT_SUPPORT
783   if (ompt) {
784     if (current_task->ompt_task_info.frame.enter_frame.ptr == NULL) {
785       current_task->ompt_task_info.frame.enter_frame.ptr =
786           taskdata->ompt_task_info.frame.exit_frame.ptr = frame_address;
787       current_task->ompt_task_info.frame.enter_frame_flags =
788           taskdata->ompt_task_info.frame.exit_frame_flags =
789               ompt_frame_application | ompt_frame_framepointer;
790     }
791     if (ompt_enabled.ompt_callback_task_create) {
792       ompt_task_info_t *parent_info = &(current_task->ompt_task_info);
793       ompt_callbacks.ompt_callback(ompt_callback_task_create)(
794           &(parent_info->task_data), &(parent_info->frame),
795           &(taskdata->ompt_task_info.task_data),
796           ompt_task_explicit | TASK_TYPE_DETAILS_FORMAT(taskdata), 0,
797           return_address);
798     }
799     __ompt_task_start(task, current_task, gtid);
800   }
801 #endif // OMPT_SUPPORT
802 
803   KA_TRACE(10, ("__kmpc_omp_task_begin_if0(exit): T#%d loc=%p task=%p,\n", gtid,
804                 loc_ref, taskdata));
805 }
806 
807 #if OMPT_SUPPORT
808 OMPT_NOINLINE
809 static void __kmpc_omp_task_begin_if0_ompt(ident_t *loc_ref, kmp_int32 gtid,
810                                            kmp_task_t *task,
811                                            void *frame_address,
812                                            void *return_address) {
813   __kmpc_omp_task_begin_if0_template<true>(loc_ref, gtid, task, frame_address,
814                                            return_address);
815 }
816 #endif // OMPT_SUPPORT
817 
818 // __kmpc_omp_task_begin_if0: report that a given serialized task has started
819 // execution
820 //
821 // loc_ref: source location information; points to beginning of task block.
822 // gtid: global thread number.
823 // task: task thunk for the started task.
824 void __kmpc_omp_task_begin_if0(ident_t *loc_ref, kmp_int32 gtid,
825                                kmp_task_t *task) {
826 #if OMPT_SUPPORT
827   if (UNLIKELY(ompt_enabled.enabled)) {
828     OMPT_STORE_RETURN_ADDRESS(gtid);
829     __kmpc_omp_task_begin_if0_ompt(loc_ref, gtid, task,
830                                    OMPT_GET_FRAME_ADDRESS(1),
831                                    OMPT_LOAD_RETURN_ADDRESS(gtid));
832     return;
833   }
834 #endif
835   __kmpc_omp_task_begin_if0_template<false>(loc_ref, gtid, task, NULL, NULL);
836 }
837 
838 #ifdef TASK_UNUSED
839 // __kmpc_omp_task_begin: report that a given task has started execution
840 // NEVER GENERATED BY COMPILER, DEPRECATED!!!
841 void __kmpc_omp_task_begin(ident_t *loc_ref, kmp_int32 gtid, kmp_task_t *task) {
842   kmp_taskdata_t *current_task = __kmp_threads[gtid]->th.th_current_task;
843 
844   KA_TRACE(
845       10,
846       ("__kmpc_omp_task_begin(enter): T#%d loc=%p task=%p current_task=%p\n",
847        gtid, loc_ref, KMP_TASK_TO_TASKDATA(task), current_task));
848 
849   __kmp_task_start(gtid, task, current_task);
850 
851   KA_TRACE(10, ("__kmpc_omp_task_begin(exit): T#%d loc=%p task=%p,\n", gtid,
852                 loc_ref, KMP_TASK_TO_TASKDATA(task)));
853   return;
854 }
855 #endif // TASK_UNUSED
856 
857 // __kmp_free_task: free the current task space and the space for shareds
858 //
859 // gtid: Global thread ID of calling thread
860 // taskdata: task to free
861 // thread: thread data structure of caller
862 static void __kmp_free_task(kmp_int32 gtid, kmp_taskdata_t *taskdata,
863                             kmp_info_t *thread) {
864   KA_TRACE(30, ("__kmp_free_task: T#%d freeing data from task %p\n", gtid,
865                 taskdata));
866 
867   // Check to make sure all flags and counters have the correct values
868   KMP_DEBUG_ASSERT(taskdata->td_flags.tasktype == TASK_EXPLICIT);
869   KMP_DEBUG_ASSERT(taskdata->td_flags.executing == 0);
870   KMP_DEBUG_ASSERT(taskdata->td_flags.complete == 1);
871   KMP_DEBUG_ASSERT(taskdata->td_flags.freed == 0);
872   KMP_DEBUG_ASSERT(taskdata->td_allocated_child_tasks == 0 ||
873                    taskdata->td_flags.task_serial == 1);
874   KMP_DEBUG_ASSERT(taskdata->td_incomplete_child_tasks == 0);
875   kmp_task_t *task = KMP_TASKDATA_TO_TASK(taskdata);
876   // Clear data to not be re-used later by mistake.
877   task->data1.destructors = NULL;
878   task->data2.priority = 0;
879 
880   taskdata->td_flags.freed = 1;
881 // deallocate the taskdata and shared variable blocks associated with this task
882 #if USE_FAST_MEMORY
883   __kmp_fast_free(thread, taskdata);
884 #else /* ! USE_FAST_MEMORY */
885   __kmp_thread_free(thread, taskdata);
886 #endif
887   KA_TRACE(20, ("__kmp_free_task: T#%d freed task %p\n", gtid, taskdata));
888 }
889 
890 // __kmp_free_task_and_ancestors: free the current task and ancestors without
891 // children
892 //
893 // gtid: Global thread ID of calling thread
894 // taskdata: task to free
895 // thread: thread data structure of caller
896 static void __kmp_free_task_and_ancestors(kmp_int32 gtid,
897                                           kmp_taskdata_t *taskdata,
898                                           kmp_info_t *thread) {
899   // Proxy tasks must always be allowed to free their parents
900   // because they can be run in background even in serial mode.
901   kmp_int32 team_serial =
902       (taskdata->td_flags.team_serial || taskdata->td_flags.tasking_ser) &&
903       !taskdata->td_flags.proxy;
904   KMP_DEBUG_ASSERT(taskdata->td_flags.tasktype == TASK_EXPLICIT);
905 
906   kmp_int32 children = KMP_ATOMIC_DEC(&taskdata->td_allocated_child_tasks) - 1;
907   KMP_DEBUG_ASSERT(children >= 0);
908 
909   // Now, go up the ancestor tree to see if any ancestors can now be freed.
910   while (children == 0) {
911     kmp_taskdata_t *parent_taskdata = taskdata->td_parent;
912 
913     KA_TRACE(20, ("__kmp_free_task_and_ancestors(enter): T#%d task %p complete "
914                   "and freeing itself\n",
915                   gtid, taskdata));
916 
917     // --- Deallocate my ancestor task ---
918     __kmp_free_task(gtid, taskdata, thread);
919 
920     taskdata = parent_taskdata;
921 
922     if (team_serial)
923       return;
924     // Stop checking ancestors at implicit task instead of walking up ancestor
925     // tree to avoid premature deallocation of ancestors.
926     if (taskdata->td_flags.tasktype == TASK_IMPLICIT) {
927       if (taskdata->td_dephash) { // do we need to cleanup dephash?
928         int children = KMP_ATOMIC_LD_ACQ(&taskdata->td_incomplete_child_tasks);
929         kmp_tasking_flags_t flags_old = taskdata->td_flags;
930         if (children == 0 && flags_old.complete == 1) {
931           kmp_tasking_flags_t flags_new = flags_old;
932           flags_new.complete = 0;
933           if (KMP_COMPARE_AND_STORE_ACQ32(
934                   RCAST(kmp_int32 *, &taskdata->td_flags),
935                   *RCAST(kmp_int32 *, &flags_old),
936                   *RCAST(kmp_int32 *, &flags_new))) {
937             KA_TRACE(100, ("__kmp_free_task_and_ancestors: T#%d cleans "
938                            "dephash of implicit task %p\n",
939                            gtid, taskdata));
940             // cleanup dephash of finished implicit task
941             __kmp_dephash_free_entries(thread, taskdata->td_dephash);
942           }
943         }
944       }
945       return;
946     }
947     // Predecrement simulated by "- 1" calculation
948     children = KMP_ATOMIC_DEC(&taskdata->td_allocated_child_tasks) - 1;
949     KMP_DEBUG_ASSERT(children >= 0);
950   }
951 
952   KA_TRACE(
953       20, ("__kmp_free_task_and_ancestors(exit): T#%d task %p has %d children; "
954            "not freeing it yet\n",
955            gtid, taskdata, children));
956 }
957 
958 // Only need to keep track of child task counts if any of the following:
959 // 1. team parallel and tasking not serialized;
960 // 2. it is a proxy or detachable or hidden helper task
961 // 3. the children counter of its parent task is greater than 0.
962 // The reason for the 3rd one is for serialized team that found detached task,
963 // hidden helper task, T. In this case, the execution of T is still deferred,
964 // and it is also possible that a regular task depends on T. In this case, if we
965 // don't track the children, task synchronization will be broken.
966 static bool __kmp_track_children_task(kmp_taskdata_t *taskdata) {
967   kmp_tasking_flags_t flags = taskdata->td_flags;
968   bool ret = !(flags.team_serial || flags.tasking_ser);
969   ret = ret || flags.proxy == TASK_PROXY ||
970         flags.detachable == TASK_DETACHABLE || flags.hidden_helper;
971   ret = ret ||
972         KMP_ATOMIC_LD_ACQ(&taskdata->td_parent->td_incomplete_child_tasks) > 0;
973   return ret;
974 }
975 
976 // __kmp_task_finish: bookkeeping to do when a task finishes execution
977 //
978 // gtid: global thread ID for calling thread
979 // task: task to be finished
980 // resumed_task: task to be resumed.  (may be NULL if task is serialized)
981 //
982 // template<ompt>: effectively ompt_enabled.enabled!=0
983 // the version with ompt=false is inlined, allowing to optimize away all ompt
984 // code in this case
985 template <bool ompt>
986 static void __kmp_task_finish(kmp_int32 gtid, kmp_task_t *task,
987                               kmp_taskdata_t *resumed_task) {
988   kmp_taskdata_t *taskdata = KMP_TASK_TO_TASKDATA(task);
989   kmp_info_t *thread = __kmp_threads[gtid];
990   kmp_task_team_t *task_team =
991       thread->th.th_task_team; // might be NULL for serial teams...
992 #if KMP_DEBUG
993   kmp_int32 children = 0;
994 #endif
995   KA_TRACE(10, ("__kmp_task_finish(enter): T#%d finishing task %p and resuming "
996                 "task %p\n",
997                 gtid, taskdata, resumed_task));
998 
999   KMP_DEBUG_ASSERT(taskdata->td_flags.tasktype == TASK_EXPLICIT);
1000 
1001 // Pop task from stack if tied
1002 #ifdef BUILD_TIED_TASK_STACK
1003   if (taskdata->td_flags.tiedness == TASK_TIED) {
1004     __kmp_pop_task_stack(gtid, thread, taskdata);
1005   }
1006 #endif /* BUILD_TIED_TASK_STACK */
1007 
1008   if (UNLIKELY(taskdata->td_flags.tiedness == TASK_UNTIED)) {
1009     // untied task needs to check the counter so that the task structure is not
1010     // freed prematurely
1011     kmp_int32 counter = KMP_ATOMIC_DEC(&taskdata->td_untied_count) - 1;
1012     KA_TRACE(
1013         20,
1014         ("__kmp_task_finish: T#%d untied_count (%d) decremented for task %p\n",
1015          gtid, counter, taskdata));
1016     if (counter > 0) {
1017       // untied task is not done, to be continued possibly by other thread, do
1018       // not free it now
1019       if (resumed_task == NULL) {
1020         KMP_DEBUG_ASSERT(taskdata->td_flags.task_serial);
1021         resumed_task = taskdata->td_parent; // In a serialized task, the resumed
1022         // task is the parent
1023       }
1024       thread->th.th_current_task = resumed_task; // restore current_task
1025       resumed_task->td_flags.executing = 1; // resume previous task
1026       KA_TRACE(10, ("__kmp_task_finish(exit): T#%d partially done task %p, "
1027                     "resuming task %p\n",
1028                     gtid, taskdata, resumed_task));
1029       return;
1030     }
1031   }
1032 
1033   // bookkeeping for resuming task:
1034   // GEH - note tasking_ser => task_serial
1035   KMP_DEBUG_ASSERT(
1036       (taskdata->td_flags.tasking_ser || taskdata->td_flags.task_serial) ==
1037       taskdata->td_flags.task_serial);
1038   if (taskdata->td_flags.task_serial) {
1039     if (resumed_task == NULL) {
1040       resumed_task = taskdata->td_parent; // In a serialized task, the resumed
1041       // task is the parent
1042     }
1043   } else {
1044     KMP_DEBUG_ASSERT(resumed_task !=
1045                      NULL); // verify that resumed task is passed as argument
1046   }
1047 
1048   /* If the tasks' destructor thunk flag has been set, we need to invoke the
1049      destructor thunk that has been generated by the compiler. The code is
1050      placed here, since at this point other tasks might have been released
1051      hence overlapping the destructor invocations with some other work in the
1052      released tasks.  The OpenMP spec is not specific on when the destructors
1053      are invoked, so we should be free to choose. */
1054   if (UNLIKELY(taskdata->td_flags.destructors_thunk)) {
1055     kmp_routine_entry_t destr_thunk = task->data1.destructors;
1056     KMP_ASSERT(destr_thunk);
1057     destr_thunk(gtid, task);
1058   }
1059 
1060   KMP_DEBUG_ASSERT(taskdata->td_flags.complete == 0);
1061   KMP_DEBUG_ASSERT(taskdata->td_flags.started == 1);
1062   KMP_DEBUG_ASSERT(taskdata->td_flags.freed == 0);
1063 
1064   bool detach = false;
1065   if (UNLIKELY(taskdata->td_flags.detachable == TASK_DETACHABLE)) {
1066     if (taskdata->td_allow_completion_event.type ==
1067         KMP_EVENT_ALLOW_COMPLETION) {
1068       // event hasn't been fulfilled yet. Try to detach task.
1069       __kmp_acquire_tas_lock(&taskdata->td_allow_completion_event.lock, gtid);
1070       if (taskdata->td_allow_completion_event.type ==
1071           KMP_EVENT_ALLOW_COMPLETION) {
1072         // task finished execution
1073         KMP_DEBUG_ASSERT(taskdata->td_flags.executing == 1);
1074         taskdata->td_flags.executing = 0; // suspend the finishing task
1075 
1076 #if OMPT_SUPPORT
1077         // For a detached task, which is not completed, we switch back
1078         // the omp_fulfill_event signals completion
1079         // locking is necessary to avoid a race with ompt_task_late_fulfill
1080         if (ompt)
1081           __ompt_task_finish(task, resumed_task, ompt_task_detach);
1082 #endif
1083 
1084         // no access to taskdata after this point!
1085         // __kmp_fulfill_event might free taskdata at any time from now
1086 
1087         taskdata->td_flags.proxy = TASK_PROXY; // proxify!
1088         detach = true;
1089       }
1090       __kmp_release_tas_lock(&taskdata->td_allow_completion_event.lock, gtid);
1091     }
1092   }
1093 
1094   if (!detach) {
1095     taskdata->td_flags.complete = 1; // mark the task as completed
1096 
1097 #if OMPT_SUPPORT
1098     // This is not a detached task, we are done here
1099     if (ompt)
1100       __ompt_task_finish(task, resumed_task, ompt_task_complete);
1101 #endif
1102     // TODO: What would be the balance between the conditions in the function
1103     // and an atomic operation?
1104     if (__kmp_track_children_task(taskdata)) {
1105       __kmp_release_deps(gtid, taskdata);
1106       // Predecrement simulated by "- 1" calculation
1107 #if KMP_DEBUG
1108       children = -1 +
1109 #endif
1110           KMP_ATOMIC_DEC(&taskdata->td_parent->td_incomplete_child_tasks);
1111       KMP_DEBUG_ASSERT(children >= 0);
1112       if (taskdata->td_taskgroup)
1113         KMP_ATOMIC_DEC(&taskdata->td_taskgroup->count);
1114     } else if (task_team && (task_team->tt.tt_found_proxy_tasks ||
1115                              task_team->tt.tt_hidden_helper_task_encountered)) {
1116       // if we found proxy or hidden helper tasks there could exist a dependency
1117       // chain with the proxy task as origin
1118       __kmp_release_deps(gtid, taskdata);
1119     }
1120     // td_flags.executing must be marked as 0 after __kmp_release_deps has been
1121     // called. Othertwise, if a task is executed immediately from the
1122     // release_deps code, the flag will be reset to 1 again by this same
1123     // function
1124     KMP_DEBUG_ASSERT(taskdata->td_flags.executing == 1);
1125     taskdata->td_flags.executing = 0; // suspend the finishing task
1126   }
1127 
1128   KA_TRACE(
1129       20, ("__kmp_task_finish: T#%d finished task %p, %d incomplete children\n",
1130            gtid, taskdata, children));
1131 
1132   // Free this task and then ancestor tasks if they have no children.
1133   // Restore th_current_task first as suggested by John:
1134   // johnmc: if an asynchronous inquiry peers into the runtime system
1135   // it doesn't see the freed task as the current task.
1136   thread->th.th_current_task = resumed_task;
1137   if (!detach)
1138     __kmp_free_task_and_ancestors(gtid, taskdata, thread);
1139 
1140   // TODO: GEH - make sure root team implicit task is initialized properly.
1141   // KMP_DEBUG_ASSERT( resumed_task->td_flags.executing == 0 );
1142   resumed_task->td_flags.executing = 1; // resume previous task
1143 
1144   KA_TRACE(
1145       10, ("__kmp_task_finish(exit): T#%d finished task %p, resuming task %p\n",
1146            gtid, taskdata, resumed_task));
1147 
1148   return;
1149 }
1150 
1151 template <bool ompt>
1152 static void __kmpc_omp_task_complete_if0_template(ident_t *loc_ref,
1153                                                   kmp_int32 gtid,
1154                                                   kmp_task_t *task) {
1155   KA_TRACE(10, ("__kmpc_omp_task_complete_if0(enter): T#%d loc=%p task=%p\n",
1156                 gtid, loc_ref, KMP_TASK_TO_TASKDATA(task)));
1157   KMP_DEBUG_ASSERT(gtid >= 0);
1158   // this routine will provide task to resume
1159   __kmp_task_finish<ompt>(gtid, task, NULL);
1160 
1161   KA_TRACE(10, ("__kmpc_omp_task_complete_if0(exit): T#%d loc=%p task=%p\n",
1162                 gtid, loc_ref, KMP_TASK_TO_TASKDATA(task)));
1163 
1164 #if OMPT_SUPPORT
1165   if (ompt) {
1166     ompt_frame_t *ompt_frame;
1167     __ompt_get_task_info_internal(0, NULL, NULL, &ompt_frame, NULL, NULL);
1168     ompt_frame->enter_frame = ompt_data_none;
1169     ompt_frame->enter_frame_flags =
1170         ompt_frame_runtime | ompt_frame_framepointer;
1171   }
1172 #endif
1173 
1174   return;
1175 }
1176 
1177 #if OMPT_SUPPORT
1178 OMPT_NOINLINE
1179 void __kmpc_omp_task_complete_if0_ompt(ident_t *loc_ref, kmp_int32 gtid,
1180                                        kmp_task_t *task) {
1181   __kmpc_omp_task_complete_if0_template<true>(loc_ref, gtid, task);
1182 }
1183 #endif // OMPT_SUPPORT
1184 
1185 // __kmpc_omp_task_complete_if0: report that a task has completed execution
1186 //
1187 // loc_ref: source location information; points to end of task block.
1188 // gtid: global thread number.
1189 // task: task thunk for the completed task.
1190 void __kmpc_omp_task_complete_if0(ident_t *loc_ref, kmp_int32 gtid,
1191                                   kmp_task_t *task) {
1192 #if OMPT_SUPPORT
1193   if (UNLIKELY(ompt_enabled.enabled)) {
1194     __kmpc_omp_task_complete_if0_ompt(loc_ref, gtid, task);
1195     return;
1196   }
1197 #endif
1198   __kmpc_omp_task_complete_if0_template<false>(loc_ref, gtid, task);
1199 }
1200 
1201 #ifdef TASK_UNUSED
1202 // __kmpc_omp_task_complete: report that a task has completed execution
1203 // NEVER GENERATED BY COMPILER, DEPRECATED!!!
1204 void __kmpc_omp_task_complete(ident_t *loc_ref, kmp_int32 gtid,
1205                               kmp_task_t *task) {
1206   KA_TRACE(10, ("__kmpc_omp_task_complete(enter): T#%d loc=%p task=%p\n", gtid,
1207                 loc_ref, KMP_TASK_TO_TASKDATA(task)));
1208 
1209   __kmp_task_finish<false>(gtid, task,
1210                            NULL); // Not sure how to find task to resume
1211 
1212   KA_TRACE(10, ("__kmpc_omp_task_complete(exit): T#%d loc=%p task=%p\n", gtid,
1213                 loc_ref, KMP_TASK_TO_TASKDATA(task)));
1214   return;
1215 }
1216 #endif // TASK_UNUSED
1217 
1218 // __kmp_init_implicit_task: Initialize the appropriate fields in the implicit
1219 // task for a given thread
1220 //
1221 // loc_ref:  reference to source location of parallel region
1222 // this_thr:  thread data structure corresponding to implicit task
1223 // team: team for this_thr
1224 // tid: thread id of given thread within team
1225 // set_curr_task: TRUE if need to push current task to thread
1226 // NOTE: Routine does not set up the implicit task ICVS.  This is assumed to
1227 // have already been done elsewhere.
1228 // TODO: Get better loc_ref.  Value passed in may be NULL
1229 void __kmp_init_implicit_task(ident_t *loc_ref, kmp_info_t *this_thr,
1230                               kmp_team_t *team, int tid, int set_curr_task) {
1231   kmp_taskdata_t *task = &team->t.t_implicit_task_taskdata[tid];
1232 
1233   KF_TRACE(
1234       10,
1235       ("__kmp_init_implicit_task(enter): T#:%d team=%p task=%p, reinit=%s\n",
1236        tid, team, task, set_curr_task ? "TRUE" : "FALSE"));
1237 
1238   task->td_task_id = KMP_GEN_TASK_ID();
1239   task->td_team = team;
1240   //    task->td_parent   = NULL;  // fix for CQ230101 (broken parent task info
1241   //    in debugger)
1242   task->td_ident = loc_ref;
1243   task->td_taskwait_ident = NULL;
1244   task->td_taskwait_counter = 0;
1245   task->td_taskwait_thread = 0;
1246 
1247   task->td_flags.tiedness = TASK_TIED;
1248   task->td_flags.tasktype = TASK_IMPLICIT;
1249   task->td_flags.proxy = TASK_FULL;
1250 
1251   // All implicit tasks are executed immediately, not deferred
1252   task->td_flags.task_serial = 1;
1253   task->td_flags.tasking_ser = (__kmp_tasking_mode == tskm_immediate_exec);
1254   task->td_flags.team_serial = (team->t.t_serialized) ? 1 : 0;
1255 
1256   task->td_flags.started = 1;
1257   task->td_flags.executing = 1;
1258   task->td_flags.complete = 0;
1259   task->td_flags.freed = 0;
1260 
1261   task->td_depnode = NULL;
1262   task->td_last_tied = task;
1263   task->td_allow_completion_event.type = KMP_EVENT_UNINITIALIZED;
1264 
1265   if (set_curr_task) { // only do this init first time thread is created
1266     KMP_ATOMIC_ST_REL(&task->td_incomplete_child_tasks, 0);
1267     // Not used: don't need to deallocate implicit task
1268     KMP_ATOMIC_ST_REL(&task->td_allocated_child_tasks, 0);
1269     task->td_taskgroup = NULL; // An implicit task does not have taskgroup
1270     task->td_dephash = NULL;
1271     __kmp_push_current_task_to_thread(this_thr, team, tid);
1272   } else {
1273     KMP_DEBUG_ASSERT(task->td_incomplete_child_tasks == 0);
1274     KMP_DEBUG_ASSERT(task->td_allocated_child_tasks == 0);
1275   }
1276 
1277 #if OMPT_SUPPORT
1278   if (UNLIKELY(ompt_enabled.enabled))
1279     __ompt_task_init(task, tid);
1280 #endif
1281 
1282   KF_TRACE(10, ("__kmp_init_implicit_task(exit): T#:%d team=%p task=%p\n", tid,
1283                 team, task));
1284 }
1285 
1286 // __kmp_finish_implicit_task: Release resources associated to implicit tasks
1287 // at the end of parallel regions. Some resources are kept for reuse in the next
1288 // parallel region.
1289 //
1290 // thread:  thread data structure corresponding to implicit task
1291 void __kmp_finish_implicit_task(kmp_info_t *thread) {
1292   kmp_taskdata_t *task = thread->th.th_current_task;
1293   if (task->td_dephash) {
1294     int children;
1295     task->td_flags.complete = 1;
1296     children = KMP_ATOMIC_LD_ACQ(&task->td_incomplete_child_tasks);
1297     kmp_tasking_flags_t flags_old = task->td_flags;
1298     if (children == 0 && flags_old.complete == 1) {
1299       kmp_tasking_flags_t flags_new = flags_old;
1300       flags_new.complete = 0;
1301       if (KMP_COMPARE_AND_STORE_ACQ32(RCAST(kmp_int32 *, &task->td_flags),
1302                                       *RCAST(kmp_int32 *, &flags_old),
1303                                       *RCAST(kmp_int32 *, &flags_new))) {
1304         KA_TRACE(100, ("__kmp_finish_implicit_task: T#%d cleans "
1305                        "dephash of implicit task %p\n",
1306                        thread->th.th_info.ds.ds_gtid, task));
1307         __kmp_dephash_free_entries(thread, task->td_dephash);
1308       }
1309     }
1310   }
1311 }
1312 
1313 // __kmp_free_implicit_task: Release resources associated to implicit tasks
1314 // when these are destroyed regions
1315 //
1316 // thread:  thread data structure corresponding to implicit task
1317 void __kmp_free_implicit_task(kmp_info_t *thread) {
1318   kmp_taskdata_t *task = thread->th.th_current_task;
1319   if (task && task->td_dephash) {
1320     __kmp_dephash_free(thread, task->td_dephash);
1321     task->td_dephash = NULL;
1322   }
1323 }
1324 
1325 // Round up a size to a power of two specified by val: Used to insert padding
1326 // between structures co-allocated using a single malloc() call
1327 static size_t __kmp_round_up_to_val(size_t size, size_t val) {
1328   if (size & (val - 1)) {
1329     size &= ~(val - 1);
1330     if (size <= KMP_SIZE_T_MAX - val) {
1331       size += val; // Round up if there is no overflow.
1332     }
1333   }
1334   return size;
1335 } // __kmp_round_up_to_va
1336 
1337 // __kmp_task_alloc: Allocate the taskdata and task data structures for a task
1338 //
1339 // loc_ref: source location information
1340 // gtid: global thread number.
1341 // flags: include tiedness & task type (explicit vs. implicit) of the ''new''
1342 // task encountered. Converted from kmp_int32 to kmp_tasking_flags_t in routine.
1343 // sizeof_kmp_task_t:  Size in bytes of kmp_task_t data structure including
1344 // private vars accessed in task.
1345 // sizeof_shareds:  Size in bytes of array of pointers to shared vars accessed
1346 // in task.
1347 // task_entry: Pointer to task code entry point generated by compiler.
1348 // returns: a pointer to the allocated kmp_task_t structure (task).
1349 kmp_task_t *__kmp_task_alloc(ident_t *loc_ref, kmp_int32 gtid,
1350                              kmp_tasking_flags_t *flags,
1351                              size_t sizeof_kmp_task_t, size_t sizeof_shareds,
1352                              kmp_routine_entry_t task_entry) {
1353   kmp_task_t *task;
1354   kmp_taskdata_t *taskdata;
1355   kmp_info_t *thread = __kmp_threads[gtid];
1356   kmp_team_t *team = thread->th.th_team;
1357   kmp_taskdata_t *parent_task = thread->th.th_current_task;
1358   size_t shareds_offset;
1359 
1360   if (UNLIKELY(!TCR_4(__kmp_init_middle)))
1361     __kmp_middle_initialize();
1362 
1363   if (flags->hidden_helper) {
1364     if (__kmp_enable_hidden_helper) {
1365       if (!TCR_4(__kmp_init_hidden_helper))
1366         __kmp_hidden_helper_initialize();
1367     } else {
1368       // If the hidden helper task is not enabled, reset the flag to FALSE.
1369       flags->hidden_helper = FALSE;
1370     }
1371   }
1372 
1373   KA_TRACE(10, ("__kmp_task_alloc(enter): T#%d loc=%p, flags=(0x%x) "
1374                 "sizeof_task=%ld sizeof_shared=%ld entry=%p\n",
1375                 gtid, loc_ref, *((kmp_int32 *)flags), sizeof_kmp_task_t,
1376                 sizeof_shareds, task_entry));
1377 
1378   KMP_DEBUG_ASSERT(parent_task);
1379   if (parent_task->td_flags.final) {
1380     if (flags->merged_if0) {
1381     }
1382     flags->final = 1;
1383   }
1384 
1385   if (flags->tiedness == TASK_UNTIED && !team->t.t_serialized) {
1386     // Untied task encountered causes the TSC algorithm to check entire deque of
1387     // the victim thread. If no untied task encountered, then checking the head
1388     // of the deque should be enough.
1389     KMP_CHECK_UPDATE(thread->th.th_task_team->tt.tt_untied_task_encountered, 1);
1390   }
1391 
1392   // Detachable tasks are not proxy tasks yet but could be in the future. Doing
1393   // the tasking setup
1394   // when that happens is too late.
1395   if (UNLIKELY(flags->proxy == TASK_PROXY ||
1396                flags->detachable == TASK_DETACHABLE || flags->hidden_helper)) {
1397     if (flags->proxy == TASK_PROXY) {
1398       flags->tiedness = TASK_UNTIED;
1399       flags->merged_if0 = 1;
1400     }
1401     /* are we running in a sequential parallel or tskm_immediate_exec... we need
1402        tasking support enabled */
1403     if ((thread->th.th_task_team) == NULL) {
1404       /* This should only happen if the team is serialized
1405           setup a task team and propagate it to the thread */
1406       KMP_DEBUG_ASSERT(team->t.t_serialized);
1407       KA_TRACE(30,
1408                ("T#%d creating task team in __kmp_task_alloc for proxy task\n",
1409                 gtid));
1410       // 1 indicates setup the current team regardless of nthreads
1411       __kmp_task_team_setup(thread, team, 1);
1412       thread->th.th_task_team = team->t.t_task_team[thread->th.th_task_state];
1413     }
1414     kmp_task_team_t *task_team = thread->th.th_task_team;
1415 
1416     /* tasking must be enabled now as the task might not be pushed */
1417     if (!KMP_TASKING_ENABLED(task_team)) {
1418       KA_TRACE(
1419           30,
1420           ("T#%d enabling tasking in __kmp_task_alloc for proxy task\n", gtid));
1421       __kmp_enable_tasking(task_team, thread);
1422       kmp_int32 tid = thread->th.th_info.ds.ds_tid;
1423       kmp_thread_data_t *thread_data = &task_team->tt.tt_threads_data[tid];
1424       // No lock needed since only owner can allocate
1425       if (thread_data->td.td_deque == NULL) {
1426         __kmp_alloc_task_deque(thread, thread_data);
1427       }
1428     }
1429 
1430     if ((flags->proxy == TASK_PROXY || flags->detachable == TASK_DETACHABLE) &&
1431         task_team->tt.tt_found_proxy_tasks == FALSE)
1432       TCW_4(task_team->tt.tt_found_proxy_tasks, TRUE);
1433     if (flags->hidden_helper &&
1434         task_team->tt.tt_hidden_helper_task_encountered == FALSE)
1435       TCW_4(task_team->tt.tt_hidden_helper_task_encountered, TRUE);
1436   }
1437 
1438   // Calculate shared structure offset including padding after kmp_task_t struct
1439   // to align pointers in shared struct
1440   shareds_offset = sizeof(kmp_taskdata_t) + sizeof_kmp_task_t;
1441   shareds_offset = __kmp_round_up_to_val(shareds_offset, sizeof(void *));
1442 
1443   // Allocate a kmp_taskdata_t block and a kmp_task_t block.
1444   KA_TRACE(30, ("__kmp_task_alloc: T#%d First malloc size: %ld\n", gtid,
1445                 shareds_offset));
1446   KA_TRACE(30, ("__kmp_task_alloc: T#%d Second malloc size: %ld\n", gtid,
1447                 sizeof_shareds));
1448 
1449   // Avoid double allocation here by combining shareds with taskdata
1450 #if USE_FAST_MEMORY
1451   taskdata = (kmp_taskdata_t *)__kmp_fast_allocate(thread, shareds_offset +
1452                                                                sizeof_shareds);
1453 #else /* ! USE_FAST_MEMORY */
1454   taskdata = (kmp_taskdata_t *)__kmp_thread_malloc(thread, shareds_offset +
1455                                                                sizeof_shareds);
1456 #endif /* USE_FAST_MEMORY */
1457 
1458   task = KMP_TASKDATA_TO_TASK(taskdata);
1459 
1460 // Make sure task & taskdata are aligned appropriately
1461 #if KMP_ARCH_X86 || KMP_ARCH_PPC64 || !KMP_HAVE_QUAD
1462   KMP_DEBUG_ASSERT((((kmp_uintptr_t)taskdata) & (sizeof(double) - 1)) == 0);
1463   KMP_DEBUG_ASSERT((((kmp_uintptr_t)task) & (sizeof(double) - 1)) == 0);
1464 #else
1465   KMP_DEBUG_ASSERT((((kmp_uintptr_t)taskdata) & (sizeof(_Quad) - 1)) == 0);
1466   KMP_DEBUG_ASSERT((((kmp_uintptr_t)task) & (sizeof(_Quad) - 1)) == 0);
1467 #endif
1468   if (sizeof_shareds > 0) {
1469     // Avoid double allocation here by combining shareds with taskdata
1470     task->shareds = &((char *)taskdata)[shareds_offset];
1471     // Make sure shareds struct is aligned to pointer size
1472     KMP_DEBUG_ASSERT((((kmp_uintptr_t)task->shareds) & (sizeof(void *) - 1)) ==
1473                      0);
1474   } else {
1475     task->shareds = NULL;
1476   }
1477   task->routine = task_entry;
1478   task->part_id = 0; // AC: Always start with 0 part id
1479 
1480   taskdata->td_task_id = KMP_GEN_TASK_ID();
1481   taskdata->td_team = thread->th.th_team;
1482   taskdata->td_alloc_thread = thread;
1483   taskdata->td_parent = parent_task;
1484   taskdata->td_level = parent_task->td_level + 1; // increment nesting level
1485   KMP_ATOMIC_ST_RLX(&taskdata->td_untied_count, 0);
1486   taskdata->td_ident = loc_ref;
1487   taskdata->td_taskwait_ident = NULL;
1488   taskdata->td_taskwait_counter = 0;
1489   taskdata->td_taskwait_thread = 0;
1490   KMP_DEBUG_ASSERT(taskdata->td_parent != NULL);
1491   // avoid copying icvs for proxy tasks
1492   if (flags->proxy == TASK_FULL)
1493     copy_icvs(&taskdata->td_icvs, &taskdata->td_parent->td_icvs);
1494 
1495   taskdata->td_flags = *flags;
1496   taskdata->td_task_team = thread->th.th_task_team;
1497   taskdata->td_size_alloc = shareds_offset + sizeof_shareds;
1498   taskdata->td_flags.tasktype = TASK_EXPLICIT;
1499   // If it is hidden helper task, we need to set the team and task team
1500   // correspondingly.
1501   if (flags->hidden_helper) {
1502     kmp_info_t *shadow_thread = __kmp_threads[KMP_GTID_TO_SHADOW_GTID(gtid)];
1503     taskdata->td_team = shadow_thread->th.th_team;
1504     taskdata->td_task_team = shadow_thread->th.th_task_team;
1505   }
1506 
1507   // GEH - TODO: fix this to copy parent task's value of tasking_ser flag
1508   taskdata->td_flags.tasking_ser = (__kmp_tasking_mode == tskm_immediate_exec);
1509 
1510   // GEH - TODO: fix this to copy parent task's value of team_serial flag
1511   taskdata->td_flags.team_serial = (team->t.t_serialized) ? 1 : 0;
1512 
1513   // GEH - Note we serialize the task if the team is serialized to make sure
1514   // implicit parallel region tasks are not left until program termination to
1515   // execute. Also, it helps locality to execute immediately.
1516 
1517   taskdata->td_flags.task_serial =
1518       (parent_task->td_flags.final || taskdata->td_flags.team_serial ||
1519        taskdata->td_flags.tasking_ser || flags->merged_if0);
1520 
1521   taskdata->td_flags.started = 0;
1522   taskdata->td_flags.executing = 0;
1523   taskdata->td_flags.complete = 0;
1524   taskdata->td_flags.freed = 0;
1525 
1526   KMP_ATOMIC_ST_RLX(&taskdata->td_incomplete_child_tasks, 0);
1527   // start at one because counts current task and children
1528   KMP_ATOMIC_ST_RLX(&taskdata->td_allocated_child_tasks, 1);
1529   taskdata->td_taskgroup =
1530       parent_task->td_taskgroup; // task inherits taskgroup from the parent task
1531   taskdata->td_dephash = NULL;
1532   taskdata->td_depnode = NULL;
1533   if (flags->tiedness == TASK_UNTIED)
1534     taskdata->td_last_tied = NULL; // will be set when the task is scheduled
1535   else
1536     taskdata->td_last_tied = taskdata;
1537   taskdata->td_allow_completion_event.type = KMP_EVENT_UNINITIALIZED;
1538 #if OMPT_SUPPORT
1539   if (UNLIKELY(ompt_enabled.enabled))
1540     __ompt_task_init(taskdata, gtid);
1541 #endif
1542   // TODO: What would be the balance between the conditions in the function and
1543   // an atomic operation?
1544   if (__kmp_track_children_task(taskdata)) {
1545     KMP_ATOMIC_INC(&parent_task->td_incomplete_child_tasks);
1546     if (parent_task->td_taskgroup)
1547       KMP_ATOMIC_INC(&parent_task->td_taskgroup->count);
1548     // Only need to keep track of allocated child tasks for explicit tasks since
1549     // implicit not deallocated
1550     if (taskdata->td_parent->td_flags.tasktype == TASK_EXPLICIT) {
1551       KMP_ATOMIC_INC(&taskdata->td_parent->td_allocated_child_tasks);
1552     }
1553     if (flags->hidden_helper) {
1554       taskdata->td_flags.task_serial = FALSE;
1555       // Increment the number of hidden helper tasks to be executed
1556       KMP_ATOMIC_INC(&__kmp_unexecuted_hidden_helper_tasks);
1557     }
1558   }
1559 
1560   KA_TRACE(20, ("__kmp_task_alloc(exit): T#%d created task %p parent=%p\n",
1561                 gtid, taskdata, taskdata->td_parent));
1562 
1563   return task;
1564 }
1565 
1566 kmp_task_t *__kmpc_omp_task_alloc(ident_t *loc_ref, kmp_int32 gtid,
1567                                   kmp_int32 flags, size_t sizeof_kmp_task_t,
1568                                   size_t sizeof_shareds,
1569                                   kmp_routine_entry_t task_entry) {
1570   kmp_task_t *retval;
1571   kmp_tasking_flags_t *input_flags = (kmp_tasking_flags_t *)&flags;
1572   __kmp_assert_valid_gtid(gtid);
1573   input_flags->native = FALSE;
1574   // __kmp_task_alloc() sets up all other runtime flags
1575   KA_TRACE(10, ("__kmpc_omp_task_alloc(enter): T#%d loc=%p, flags=(%s %s %s) "
1576                 "sizeof_task=%ld sizeof_shared=%ld entry=%p\n",
1577                 gtid, loc_ref, input_flags->tiedness ? "tied  " : "untied",
1578                 input_flags->proxy ? "proxy" : "",
1579                 input_flags->detachable ? "detachable" : "", sizeof_kmp_task_t,
1580                 sizeof_shareds, task_entry));
1581 
1582   retval = __kmp_task_alloc(loc_ref, gtid, input_flags, sizeof_kmp_task_t,
1583                             sizeof_shareds, task_entry);
1584 
1585   KA_TRACE(20, ("__kmpc_omp_task_alloc(exit): T#%d retval %p\n", gtid, retval));
1586 
1587   return retval;
1588 }
1589 
1590 kmp_task_t *__kmpc_omp_target_task_alloc(ident_t *loc_ref, kmp_int32 gtid,
1591                                          kmp_int32 flags,
1592                                          size_t sizeof_kmp_task_t,
1593                                          size_t sizeof_shareds,
1594                                          kmp_routine_entry_t task_entry,
1595                                          kmp_int64 device_id) {
1596   auto &input_flags = reinterpret_cast<kmp_tasking_flags_t &>(flags);
1597   // target task is untied defined in the specification
1598   input_flags.tiedness = TASK_UNTIED;
1599 
1600   if (__kmp_enable_hidden_helper)
1601     input_flags.hidden_helper = TRUE;
1602 
1603   return __kmpc_omp_task_alloc(loc_ref, gtid, flags, sizeof_kmp_task_t,
1604                                sizeof_shareds, task_entry);
1605 }
1606 
1607 /*!
1608 @ingroup TASKING
1609 @param loc_ref location of the original task directive
1610 @param gtid Global Thread ID of encountering thread
1611 @param new_task task thunk allocated by __kmpc_omp_task_alloc() for the ''new
1612 task''
1613 @param naffins Number of affinity items
1614 @param affin_list List of affinity items
1615 @return Returns non-zero if registering affinity information was not successful.
1616  Returns 0 if registration was successful
1617 This entry registers the affinity information attached to a task with the task
1618 thunk structure kmp_taskdata_t.
1619 */
1620 kmp_int32
1621 __kmpc_omp_reg_task_with_affinity(ident_t *loc_ref, kmp_int32 gtid,
1622                                   kmp_task_t *new_task, kmp_int32 naffins,
1623                                   kmp_task_affinity_info_t *affin_list) {
1624   return 0;
1625 }
1626 
1627 //  __kmp_invoke_task: invoke the specified task
1628 //
1629 // gtid: global thread ID of caller
1630 // task: the task to invoke
1631 // current_task: the task to resume after task invocation
1632 static void __kmp_invoke_task(kmp_int32 gtid, kmp_task_t *task,
1633                               kmp_taskdata_t *current_task) {
1634   kmp_taskdata_t *taskdata = KMP_TASK_TO_TASKDATA(task);
1635   kmp_info_t *thread;
1636   int discard = 0 /* false */;
1637   KA_TRACE(
1638       30, ("__kmp_invoke_task(enter): T#%d invoking task %p, current_task=%p\n",
1639            gtid, taskdata, current_task));
1640   KMP_DEBUG_ASSERT(task);
1641   if (UNLIKELY(taskdata->td_flags.proxy == TASK_PROXY &&
1642                taskdata->td_flags.complete == 1)) {
1643     // This is a proxy task that was already completed but it needs to run
1644     // its bottom-half finish
1645     KA_TRACE(
1646         30,
1647         ("__kmp_invoke_task: T#%d running bottom finish for proxy task %p\n",
1648          gtid, taskdata));
1649 
1650     __kmp_bottom_half_finish_proxy(gtid, task);
1651 
1652     KA_TRACE(30, ("__kmp_invoke_task(exit): T#%d completed bottom finish for "
1653                   "proxy task %p, resuming task %p\n",
1654                   gtid, taskdata, current_task));
1655 
1656     return;
1657   }
1658 
1659 #if OMPT_SUPPORT
1660   // For untied tasks, the first task executed only calls __kmpc_omp_task and
1661   // does not execute code.
1662   ompt_thread_info_t oldInfo;
1663   if (UNLIKELY(ompt_enabled.enabled)) {
1664     // Store the threads states and restore them after the task
1665     thread = __kmp_threads[gtid];
1666     oldInfo = thread->th.ompt_thread_info;
1667     thread->th.ompt_thread_info.wait_id = 0;
1668     thread->th.ompt_thread_info.state = (thread->th.th_team_serialized)
1669                                             ? ompt_state_work_serial
1670                                             : ompt_state_work_parallel;
1671     taskdata->ompt_task_info.frame.exit_frame.ptr = OMPT_GET_FRAME_ADDRESS(0);
1672   }
1673 #endif
1674 
1675   // Decreament the counter of hidden helper tasks to be executed
1676   if (taskdata->td_flags.hidden_helper) {
1677     // Hidden helper tasks can only be executed by hidden helper threads
1678     KMP_ASSERT(KMP_HIDDEN_HELPER_THREAD(gtid));
1679     KMP_ATOMIC_DEC(&__kmp_unexecuted_hidden_helper_tasks);
1680   }
1681 
1682   // Proxy tasks are not handled by the runtime
1683   if (taskdata->td_flags.proxy != TASK_PROXY) {
1684     __kmp_task_start(gtid, task, current_task); // OMPT only if not discarded
1685   }
1686 
1687   // TODO: cancel tasks if the parallel region has also been cancelled
1688   // TODO: check if this sequence can be hoisted above __kmp_task_start
1689   // if cancellation has been enabled for this run ...
1690   if (UNLIKELY(__kmp_omp_cancellation)) {
1691     thread = __kmp_threads[gtid];
1692     kmp_team_t *this_team = thread->th.th_team;
1693     kmp_taskgroup_t *taskgroup = taskdata->td_taskgroup;
1694     if ((taskgroup && taskgroup->cancel_request) ||
1695         (this_team->t.t_cancel_request == cancel_parallel)) {
1696 #if OMPT_SUPPORT && OMPT_OPTIONAL
1697       ompt_data_t *task_data;
1698       if (UNLIKELY(ompt_enabled.ompt_callback_cancel)) {
1699         __ompt_get_task_info_internal(0, NULL, &task_data, NULL, NULL, NULL);
1700         ompt_callbacks.ompt_callback(ompt_callback_cancel)(
1701             task_data,
1702             ((taskgroup && taskgroup->cancel_request) ? ompt_cancel_taskgroup
1703                                                       : ompt_cancel_parallel) |
1704                 ompt_cancel_discarded_task,
1705             NULL);
1706       }
1707 #endif
1708       KMP_COUNT_BLOCK(TASK_cancelled);
1709       // this task belongs to a task group and we need to cancel it
1710       discard = 1 /* true */;
1711     }
1712   }
1713 
1714   // Invoke the task routine and pass in relevant data.
1715   // Thunks generated by gcc take a different argument list.
1716   if (!discard) {
1717     if (taskdata->td_flags.tiedness == TASK_UNTIED) {
1718       taskdata->td_last_tied = current_task->td_last_tied;
1719       KMP_DEBUG_ASSERT(taskdata->td_last_tied);
1720     }
1721 #if KMP_STATS_ENABLED
1722     KMP_COUNT_BLOCK(TASK_executed);
1723     switch (KMP_GET_THREAD_STATE()) {
1724     case FORK_JOIN_BARRIER:
1725       KMP_PUSH_PARTITIONED_TIMER(OMP_task_join_bar);
1726       break;
1727     case PLAIN_BARRIER:
1728       KMP_PUSH_PARTITIONED_TIMER(OMP_task_plain_bar);
1729       break;
1730     case TASKYIELD:
1731       KMP_PUSH_PARTITIONED_TIMER(OMP_task_taskyield);
1732       break;
1733     case TASKWAIT:
1734       KMP_PUSH_PARTITIONED_TIMER(OMP_task_taskwait);
1735       break;
1736     case TASKGROUP:
1737       KMP_PUSH_PARTITIONED_TIMER(OMP_task_taskgroup);
1738       break;
1739     default:
1740       KMP_PUSH_PARTITIONED_TIMER(OMP_task_immediate);
1741       break;
1742     }
1743 #endif // KMP_STATS_ENABLED
1744 
1745 // OMPT task begin
1746 #if OMPT_SUPPORT
1747     if (UNLIKELY(ompt_enabled.enabled))
1748       __ompt_task_start(task, current_task, gtid);
1749 #endif
1750 
1751 #if OMPD_SUPPORT
1752     if (ompd_state & OMPD_ENABLE_BP)
1753       ompd_bp_task_begin();
1754 #endif
1755 
1756 #if USE_ITT_BUILD && USE_ITT_NOTIFY
1757     kmp_uint64 cur_time;
1758     kmp_int32 kmp_itt_count_task =
1759         __kmp_forkjoin_frames_mode == 3 && !taskdata->td_flags.task_serial &&
1760         current_task->td_flags.tasktype == TASK_IMPLICIT;
1761     if (kmp_itt_count_task) {
1762       thread = __kmp_threads[gtid];
1763       // Time outer level explicit task on barrier for adjusting imbalance time
1764       if (thread->th.th_bar_arrive_time)
1765         cur_time = __itt_get_timestamp();
1766       else
1767         kmp_itt_count_task = 0; // thread is not on a barrier - skip timing
1768     }
1769     KMP_FSYNC_ACQUIRED(taskdata); // acquired self (new task)
1770 #endif
1771 
1772     if (task->routine != NULL) {
1773 #ifdef KMP_GOMP_COMPAT
1774       if (taskdata->td_flags.native) {
1775         ((void (*)(void *))(*(task->routine)))(task->shareds);
1776       } else
1777 #endif /* KMP_GOMP_COMPAT */
1778       {
1779         (*(task->routine))(gtid, task);
1780       }
1781     }
1782     KMP_POP_PARTITIONED_TIMER();
1783 
1784 #if USE_ITT_BUILD && USE_ITT_NOTIFY
1785     if (kmp_itt_count_task) {
1786       // Barrier imbalance - adjust arrive time with the task duration
1787       thread->th.th_bar_arrive_time += (__itt_get_timestamp() - cur_time);
1788     }
1789     KMP_FSYNC_CANCEL(taskdata); // destroy self (just executed)
1790     KMP_FSYNC_RELEASING(taskdata->td_parent); // releasing parent
1791 #endif
1792   }
1793 
1794 #if OMPD_SUPPORT
1795   if (ompd_state & OMPD_ENABLE_BP)
1796     ompd_bp_task_end();
1797 #endif
1798 
1799   // Proxy tasks are not handled by the runtime
1800   if (taskdata->td_flags.proxy != TASK_PROXY) {
1801 #if OMPT_SUPPORT
1802     if (UNLIKELY(ompt_enabled.enabled)) {
1803       thread->th.ompt_thread_info = oldInfo;
1804       if (taskdata->td_flags.tiedness == TASK_TIED) {
1805         taskdata->ompt_task_info.frame.exit_frame = ompt_data_none;
1806       }
1807       __kmp_task_finish<true>(gtid, task, current_task);
1808     } else
1809 #endif
1810       __kmp_task_finish<false>(gtid, task, current_task);
1811   }
1812 
1813   KA_TRACE(
1814       30,
1815       ("__kmp_invoke_task(exit): T#%d completed task %p, resuming task %p\n",
1816        gtid, taskdata, current_task));
1817   return;
1818 }
1819 
1820 // __kmpc_omp_task_parts: Schedule a thread-switchable task for execution
1821 //
1822 // loc_ref: location of original task pragma (ignored)
1823 // gtid: Global Thread ID of encountering thread
1824 // new_task: task thunk allocated by __kmp_omp_task_alloc() for the ''new task''
1825 // Returns:
1826 //    TASK_CURRENT_NOT_QUEUED (0) if did not suspend and queue current task to
1827 //    be resumed later.
1828 //    TASK_CURRENT_QUEUED (1) if suspended and queued the current task to be
1829 //    resumed later.
1830 kmp_int32 __kmpc_omp_task_parts(ident_t *loc_ref, kmp_int32 gtid,
1831                                 kmp_task_t *new_task) {
1832   kmp_taskdata_t *new_taskdata = KMP_TASK_TO_TASKDATA(new_task);
1833 
1834   KA_TRACE(10, ("__kmpc_omp_task_parts(enter): T#%d loc=%p task=%p\n", gtid,
1835                 loc_ref, new_taskdata));
1836 
1837 #if OMPT_SUPPORT
1838   kmp_taskdata_t *parent;
1839   if (UNLIKELY(ompt_enabled.enabled)) {
1840     parent = new_taskdata->td_parent;
1841     if (ompt_enabled.ompt_callback_task_create) {
1842       ompt_callbacks.ompt_callback(ompt_callback_task_create)(
1843           &(parent->ompt_task_info.task_data), &(parent->ompt_task_info.frame),
1844           &(new_taskdata->ompt_task_info.task_data), ompt_task_explicit, 0,
1845           OMPT_GET_RETURN_ADDRESS(0));
1846     }
1847   }
1848 #endif
1849 
1850   /* Should we execute the new task or queue it? For now, let's just always try
1851      to queue it.  If the queue fills up, then we'll execute it.  */
1852 
1853   if (__kmp_push_task(gtid, new_task) == TASK_NOT_PUSHED) // if cannot defer
1854   { // Execute this task immediately
1855     kmp_taskdata_t *current_task = __kmp_threads[gtid]->th.th_current_task;
1856     new_taskdata->td_flags.task_serial = 1;
1857     __kmp_invoke_task(gtid, new_task, current_task);
1858   }
1859 
1860   KA_TRACE(
1861       10,
1862       ("__kmpc_omp_task_parts(exit): T#%d returning TASK_CURRENT_NOT_QUEUED: "
1863        "loc=%p task=%p, return: TASK_CURRENT_NOT_QUEUED\n",
1864        gtid, loc_ref, new_taskdata));
1865 
1866 #if OMPT_SUPPORT
1867   if (UNLIKELY(ompt_enabled.enabled)) {
1868     parent->ompt_task_info.frame.enter_frame = ompt_data_none;
1869   }
1870 #endif
1871   return TASK_CURRENT_NOT_QUEUED;
1872 }
1873 
1874 // __kmp_omp_task: Schedule a non-thread-switchable task for execution
1875 //
1876 // gtid: Global Thread ID of encountering thread
1877 // new_task:non-thread-switchable task thunk allocated by __kmp_omp_task_alloc()
1878 // serialize_immediate: if TRUE then if the task is executed immediately its
1879 // execution will be serialized
1880 // Returns:
1881 //    TASK_CURRENT_NOT_QUEUED (0) if did not suspend and queue current task to
1882 //    be resumed later.
1883 //    TASK_CURRENT_QUEUED (1) if suspended and queued the current task to be
1884 //    resumed later.
1885 kmp_int32 __kmp_omp_task(kmp_int32 gtid, kmp_task_t *new_task,
1886                          bool serialize_immediate) {
1887   kmp_taskdata_t *new_taskdata = KMP_TASK_TO_TASKDATA(new_task);
1888 
1889   /* Should we execute the new task or queue it? For now, let's just always try
1890      to queue it.  If the queue fills up, then we'll execute it.  */
1891   if (new_taskdata->td_flags.proxy == TASK_PROXY ||
1892       __kmp_push_task(gtid, new_task) == TASK_NOT_PUSHED) // if cannot defer
1893   { // Execute this task immediately
1894     kmp_taskdata_t *current_task = __kmp_threads[gtid]->th.th_current_task;
1895     if (serialize_immediate)
1896       new_taskdata->td_flags.task_serial = 1;
1897     __kmp_invoke_task(gtid, new_task, current_task);
1898   }
1899 
1900   return TASK_CURRENT_NOT_QUEUED;
1901 }
1902 
1903 // __kmpc_omp_task: Wrapper around __kmp_omp_task to schedule a
1904 // non-thread-switchable task from the parent thread only!
1905 //
1906 // loc_ref: location of original task pragma (ignored)
1907 // gtid: Global Thread ID of encountering thread
1908 // new_task: non-thread-switchable task thunk allocated by
1909 // __kmp_omp_task_alloc()
1910 // Returns:
1911 //    TASK_CURRENT_NOT_QUEUED (0) if did not suspend and queue current task to
1912 //    be resumed later.
1913 //    TASK_CURRENT_QUEUED (1) if suspended and queued the current task to be
1914 //    resumed later.
1915 kmp_int32 __kmpc_omp_task(ident_t *loc_ref, kmp_int32 gtid,
1916                           kmp_task_t *new_task) {
1917   kmp_int32 res;
1918   KMP_SET_THREAD_STATE_BLOCK(EXPLICIT_TASK);
1919 
1920 #if KMP_DEBUG || OMPT_SUPPORT
1921   kmp_taskdata_t *new_taskdata = KMP_TASK_TO_TASKDATA(new_task);
1922 #endif
1923   KA_TRACE(10, ("__kmpc_omp_task(enter): T#%d loc=%p task=%p\n", gtid, loc_ref,
1924                 new_taskdata));
1925   __kmp_assert_valid_gtid(gtid);
1926 
1927 #if OMPT_SUPPORT
1928   kmp_taskdata_t *parent = NULL;
1929   if (UNLIKELY(ompt_enabled.enabled)) {
1930     if (!new_taskdata->td_flags.started) {
1931       OMPT_STORE_RETURN_ADDRESS(gtid);
1932       parent = new_taskdata->td_parent;
1933       if (!parent->ompt_task_info.frame.enter_frame.ptr) {
1934         parent->ompt_task_info.frame.enter_frame.ptr =
1935             OMPT_GET_FRAME_ADDRESS(0);
1936       }
1937       if (ompt_enabled.ompt_callback_task_create) {
1938         ompt_callbacks.ompt_callback(ompt_callback_task_create)(
1939             &(parent->ompt_task_info.task_data),
1940             &(parent->ompt_task_info.frame),
1941             &(new_taskdata->ompt_task_info.task_data),
1942             ompt_task_explicit | TASK_TYPE_DETAILS_FORMAT(new_taskdata), 0,
1943             OMPT_LOAD_RETURN_ADDRESS(gtid));
1944       }
1945     } else {
1946       // We are scheduling the continuation of an UNTIED task.
1947       // Scheduling back to the parent task.
1948       __ompt_task_finish(new_task,
1949                          new_taskdata->ompt_task_info.scheduling_parent,
1950                          ompt_task_switch);
1951       new_taskdata->ompt_task_info.frame.exit_frame = ompt_data_none;
1952     }
1953   }
1954 #endif
1955 
1956   res = __kmp_omp_task(gtid, new_task, true);
1957 
1958   KA_TRACE(10, ("__kmpc_omp_task(exit): T#%d returning "
1959                 "TASK_CURRENT_NOT_QUEUED: loc=%p task=%p\n",
1960                 gtid, loc_ref, new_taskdata));
1961 #if OMPT_SUPPORT
1962   if (UNLIKELY(ompt_enabled.enabled && parent != NULL)) {
1963     parent->ompt_task_info.frame.enter_frame = ompt_data_none;
1964   }
1965 #endif
1966   return res;
1967 }
1968 
1969 // __kmp_omp_taskloop_task: Wrapper around __kmp_omp_task to schedule
1970 // a taskloop task with the correct OMPT return address
1971 //
1972 // loc_ref: location of original task pragma (ignored)
1973 // gtid: Global Thread ID of encountering thread
1974 // new_task: non-thread-switchable task thunk allocated by
1975 // __kmp_omp_task_alloc()
1976 // codeptr_ra: return address for OMPT callback
1977 // Returns:
1978 //    TASK_CURRENT_NOT_QUEUED (0) if did not suspend and queue current task to
1979 //    be resumed later.
1980 //    TASK_CURRENT_QUEUED (1) if suspended and queued the current task to be
1981 //    resumed later.
1982 kmp_int32 __kmp_omp_taskloop_task(ident_t *loc_ref, kmp_int32 gtid,
1983                                   kmp_task_t *new_task, void *codeptr_ra) {
1984   kmp_int32 res;
1985   KMP_SET_THREAD_STATE_BLOCK(EXPLICIT_TASK);
1986 
1987 #if KMP_DEBUG || OMPT_SUPPORT
1988   kmp_taskdata_t *new_taskdata = KMP_TASK_TO_TASKDATA(new_task);
1989 #endif
1990   KA_TRACE(10, ("__kmpc_omp_task(enter): T#%d loc=%p task=%p\n", gtid, loc_ref,
1991                 new_taskdata));
1992 
1993 #if OMPT_SUPPORT
1994   kmp_taskdata_t *parent = NULL;
1995   if (UNLIKELY(ompt_enabled.enabled && !new_taskdata->td_flags.started)) {
1996     parent = new_taskdata->td_parent;
1997     if (!parent->ompt_task_info.frame.enter_frame.ptr)
1998       parent->ompt_task_info.frame.enter_frame.ptr = OMPT_GET_FRAME_ADDRESS(0);
1999     if (ompt_enabled.ompt_callback_task_create) {
2000       ompt_callbacks.ompt_callback(ompt_callback_task_create)(
2001           &(parent->ompt_task_info.task_data), &(parent->ompt_task_info.frame),
2002           &(new_taskdata->ompt_task_info.task_data),
2003           ompt_task_explicit | TASK_TYPE_DETAILS_FORMAT(new_taskdata), 0,
2004           codeptr_ra);
2005     }
2006   }
2007 #endif
2008 
2009   res = __kmp_omp_task(gtid, new_task, true);
2010 
2011   KA_TRACE(10, ("__kmpc_omp_task(exit): T#%d returning "
2012                 "TASK_CURRENT_NOT_QUEUED: loc=%p task=%p\n",
2013                 gtid, loc_ref, new_taskdata));
2014 #if OMPT_SUPPORT
2015   if (UNLIKELY(ompt_enabled.enabled && parent != NULL)) {
2016     parent->ompt_task_info.frame.enter_frame = ompt_data_none;
2017   }
2018 #endif
2019   return res;
2020 }
2021 
2022 template <bool ompt>
2023 static kmp_int32 __kmpc_omp_taskwait_template(ident_t *loc_ref, kmp_int32 gtid,
2024                                               void *frame_address,
2025                                               void *return_address) {
2026   kmp_taskdata_t *taskdata = nullptr;
2027   kmp_info_t *thread;
2028   int thread_finished = FALSE;
2029   KMP_SET_THREAD_STATE_BLOCK(TASKWAIT);
2030 
2031   KA_TRACE(10, ("__kmpc_omp_taskwait(enter): T#%d loc=%p\n", gtid, loc_ref));
2032   KMP_DEBUG_ASSERT(gtid >= 0);
2033 
2034   if (__kmp_tasking_mode != tskm_immediate_exec) {
2035     thread = __kmp_threads[gtid];
2036     taskdata = thread->th.th_current_task;
2037 
2038 #if OMPT_SUPPORT && OMPT_OPTIONAL
2039     ompt_data_t *my_task_data;
2040     ompt_data_t *my_parallel_data;
2041 
2042     if (ompt) {
2043       my_task_data = &(taskdata->ompt_task_info.task_data);
2044       my_parallel_data = OMPT_CUR_TEAM_DATA(thread);
2045 
2046       taskdata->ompt_task_info.frame.enter_frame.ptr = frame_address;
2047 
2048       if (ompt_enabled.ompt_callback_sync_region) {
2049         ompt_callbacks.ompt_callback(ompt_callback_sync_region)(
2050             ompt_sync_region_taskwait, ompt_scope_begin, my_parallel_data,
2051             my_task_data, return_address);
2052       }
2053 
2054       if (ompt_enabled.ompt_callback_sync_region_wait) {
2055         ompt_callbacks.ompt_callback(ompt_callback_sync_region_wait)(
2056             ompt_sync_region_taskwait, ompt_scope_begin, my_parallel_data,
2057             my_task_data, return_address);
2058       }
2059     }
2060 #endif // OMPT_SUPPORT && OMPT_OPTIONAL
2061 
2062 // Debugger: The taskwait is active. Store location and thread encountered the
2063 // taskwait.
2064 #if USE_ITT_BUILD
2065 // Note: These values are used by ITT events as well.
2066 #endif /* USE_ITT_BUILD */
2067     taskdata->td_taskwait_counter += 1;
2068     taskdata->td_taskwait_ident = loc_ref;
2069     taskdata->td_taskwait_thread = gtid + 1;
2070 
2071 #if USE_ITT_BUILD
2072     void *itt_sync_obj = NULL;
2073 #if USE_ITT_NOTIFY
2074     KMP_ITT_TASKWAIT_STARTING(itt_sync_obj);
2075 #endif /* USE_ITT_NOTIFY */
2076 #endif /* USE_ITT_BUILD */
2077 
2078     bool must_wait =
2079         !taskdata->td_flags.team_serial && !taskdata->td_flags.final;
2080 
2081     must_wait = must_wait || (thread->th.th_task_team != NULL &&
2082                               thread->th.th_task_team->tt.tt_found_proxy_tasks);
2083     // If hidden helper thread is encountered, we must enable wait here.
2084     must_wait =
2085         must_wait ||
2086         (__kmp_enable_hidden_helper && thread->th.th_task_team != NULL &&
2087          thread->th.th_task_team->tt.tt_hidden_helper_task_encountered);
2088 
2089     if (must_wait) {
2090       kmp_flag_32<false, false> flag(
2091           RCAST(std::atomic<kmp_uint32> *,
2092                 &(taskdata->td_incomplete_child_tasks)),
2093           0U);
2094       while (KMP_ATOMIC_LD_ACQ(&taskdata->td_incomplete_child_tasks) != 0) {
2095         flag.execute_tasks(thread, gtid, FALSE,
2096                            &thread_finished USE_ITT_BUILD_ARG(itt_sync_obj),
2097                            __kmp_task_stealing_constraint);
2098       }
2099     }
2100 #if USE_ITT_BUILD
2101     KMP_ITT_TASKWAIT_FINISHED(itt_sync_obj);
2102     KMP_FSYNC_ACQUIRED(taskdata); // acquire self - sync with children
2103 #endif /* USE_ITT_BUILD */
2104 
2105     // Debugger:  The taskwait is completed. Location remains, but thread is
2106     // negated.
2107     taskdata->td_taskwait_thread = -taskdata->td_taskwait_thread;
2108 
2109 #if OMPT_SUPPORT && OMPT_OPTIONAL
2110     if (ompt) {
2111       if (ompt_enabled.ompt_callback_sync_region_wait) {
2112         ompt_callbacks.ompt_callback(ompt_callback_sync_region_wait)(
2113             ompt_sync_region_taskwait, ompt_scope_end, my_parallel_data,
2114             my_task_data, return_address);
2115       }
2116       if (ompt_enabled.ompt_callback_sync_region) {
2117         ompt_callbacks.ompt_callback(ompt_callback_sync_region)(
2118             ompt_sync_region_taskwait, ompt_scope_end, my_parallel_data,
2119             my_task_data, return_address);
2120       }
2121       taskdata->ompt_task_info.frame.enter_frame = ompt_data_none;
2122     }
2123 #endif // OMPT_SUPPORT && OMPT_OPTIONAL
2124 
2125   }
2126 
2127   KA_TRACE(10, ("__kmpc_omp_taskwait(exit): T#%d task %p finished waiting, "
2128                 "returning TASK_CURRENT_NOT_QUEUED\n",
2129                 gtid, taskdata));
2130 
2131   return TASK_CURRENT_NOT_QUEUED;
2132 }
2133 
2134 #if OMPT_SUPPORT && OMPT_OPTIONAL
2135 OMPT_NOINLINE
2136 static kmp_int32 __kmpc_omp_taskwait_ompt(ident_t *loc_ref, kmp_int32 gtid,
2137                                           void *frame_address,
2138                                           void *return_address) {
2139   return __kmpc_omp_taskwait_template<true>(loc_ref, gtid, frame_address,
2140                                             return_address);
2141 }
2142 #endif // OMPT_SUPPORT && OMPT_OPTIONAL
2143 
2144 // __kmpc_omp_taskwait: Wait until all tasks generated by the current task are
2145 // complete
2146 kmp_int32 __kmpc_omp_taskwait(ident_t *loc_ref, kmp_int32 gtid) {
2147 #if OMPT_SUPPORT && OMPT_OPTIONAL
2148   if (UNLIKELY(ompt_enabled.enabled)) {
2149     OMPT_STORE_RETURN_ADDRESS(gtid);
2150     return __kmpc_omp_taskwait_ompt(loc_ref, gtid, OMPT_GET_FRAME_ADDRESS(0),
2151                                     OMPT_LOAD_RETURN_ADDRESS(gtid));
2152   }
2153 #endif
2154   return __kmpc_omp_taskwait_template<false>(loc_ref, gtid, NULL, NULL);
2155 }
2156 
2157 // __kmpc_omp_taskyield: switch to a different task
2158 kmp_int32 __kmpc_omp_taskyield(ident_t *loc_ref, kmp_int32 gtid, int end_part) {
2159   kmp_taskdata_t *taskdata = NULL;
2160   kmp_info_t *thread;
2161   int thread_finished = FALSE;
2162 
2163   KMP_COUNT_BLOCK(OMP_TASKYIELD);
2164   KMP_SET_THREAD_STATE_BLOCK(TASKYIELD);
2165 
2166   KA_TRACE(10, ("__kmpc_omp_taskyield(enter): T#%d loc=%p end_part = %d\n",
2167                 gtid, loc_ref, end_part));
2168   __kmp_assert_valid_gtid(gtid);
2169 
2170   if (__kmp_tasking_mode != tskm_immediate_exec && __kmp_init_parallel) {
2171     thread = __kmp_threads[gtid];
2172     taskdata = thread->th.th_current_task;
2173 // Should we model this as a task wait or not?
2174 // Debugger: The taskwait is active. Store location and thread encountered the
2175 // taskwait.
2176 #if USE_ITT_BUILD
2177 // Note: These values are used by ITT events as well.
2178 #endif /* USE_ITT_BUILD */
2179     taskdata->td_taskwait_counter += 1;
2180     taskdata->td_taskwait_ident = loc_ref;
2181     taskdata->td_taskwait_thread = gtid + 1;
2182 
2183 #if USE_ITT_BUILD
2184     void *itt_sync_obj = NULL;
2185 #if USE_ITT_NOTIFY
2186     KMP_ITT_TASKWAIT_STARTING(itt_sync_obj);
2187 #endif /* USE_ITT_NOTIFY */
2188 #endif /* USE_ITT_BUILD */
2189     if (!taskdata->td_flags.team_serial) {
2190       kmp_task_team_t *task_team = thread->th.th_task_team;
2191       if (task_team != NULL) {
2192         if (KMP_TASKING_ENABLED(task_team)) {
2193 #if OMPT_SUPPORT
2194           if (UNLIKELY(ompt_enabled.enabled))
2195             thread->th.ompt_thread_info.ompt_task_yielded = 1;
2196 #endif
2197           __kmp_execute_tasks_32(
2198               thread, gtid, (kmp_flag_32<> *)NULL, FALSE,
2199               &thread_finished USE_ITT_BUILD_ARG(itt_sync_obj),
2200               __kmp_task_stealing_constraint);
2201 #if OMPT_SUPPORT
2202           if (UNLIKELY(ompt_enabled.enabled))
2203             thread->th.ompt_thread_info.ompt_task_yielded = 0;
2204 #endif
2205         }
2206       }
2207     }
2208 #if USE_ITT_BUILD
2209     KMP_ITT_TASKWAIT_FINISHED(itt_sync_obj);
2210 #endif /* USE_ITT_BUILD */
2211 
2212     // Debugger:  The taskwait is completed. Location remains, but thread is
2213     // negated.
2214     taskdata->td_taskwait_thread = -taskdata->td_taskwait_thread;
2215   }
2216 
2217   KA_TRACE(10, ("__kmpc_omp_taskyield(exit): T#%d task %p resuming, "
2218                 "returning TASK_CURRENT_NOT_QUEUED\n",
2219                 gtid, taskdata));
2220 
2221   return TASK_CURRENT_NOT_QUEUED;
2222 }
2223 
2224 // Task Reduction implementation
2225 //
2226 // Note: initial implementation didn't take into account the possibility
2227 // to specify omp_orig for initializer of the UDR (user defined reduction).
2228 // Corrected implementation takes into account the omp_orig object.
2229 // Compiler is free to use old implementation if omp_orig is not specified.
2230 
2231 /*!
2232 @ingroup BASIC_TYPES
2233 @{
2234 */
2235 
2236 /*!
2237 Flags for special info per task reduction item.
2238 */
2239 typedef struct kmp_taskred_flags {
2240   /*! 1 - use lazy alloc/init (e.g. big objects, #tasks < #threads) */
2241   unsigned lazy_priv : 1;
2242   unsigned reserved31 : 31;
2243 } kmp_taskred_flags_t;
2244 
2245 /*!
2246 Internal struct for reduction data item related info set up by compiler.
2247 */
2248 typedef struct kmp_task_red_input {
2249   void *reduce_shar; /**< shared between tasks item to reduce into */
2250   size_t reduce_size; /**< size of data item in bytes */
2251   // three compiler-generated routines (init, fini are optional):
2252   void *reduce_init; /**< data initialization routine (single parameter) */
2253   void *reduce_fini; /**< data finalization routine */
2254   void *reduce_comb; /**< data combiner routine */
2255   kmp_taskred_flags_t flags; /**< flags for additional info from compiler */
2256 } kmp_task_red_input_t;
2257 
2258 /*!
2259 Internal struct for reduction data item related info saved by the library.
2260 */
2261 typedef struct kmp_taskred_data {
2262   void *reduce_shar; /**< shared between tasks item to reduce into */
2263   size_t reduce_size; /**< size of data item */
2264   kmp_taskred_flags_t flags; /**< flags for additional info from compiler */
2265   void *reduce_priv; /**< array of thread specific items */
2266   void *reduce_pend; /**< end of private data for faster comparison op */
2267   // three compiler-generated routines (init, fini are optional):
2268   void *reduce_comb; /**< data combiner routine */
2269   void *reduce_init; /**< data initialization routine (two parameters) */
2270   void *reduce_fini; /**< data finalization routine */
2271   void *reduce_orig; /**< original item (can be used in UDR initializer) */
2272 } kmp_taskred_data_t;
2273 
2274 /*!
2275 Internal struct for reduction data item related info set up by compiler.
2276 
2277 New interface: added reduce_orig field to provide omp_orig for UDR initializer.
2278 */
2279 typedef struct kmp_taskred_input {
2280   void *reduce_shar; /**< shared between tasks item to reduce into */
2281   void *reduce_orig; /**< original reduction item used for initialization */
2282   size_t reduce_size; /**< size of data item */
2283   // three compiler-generated routines (init, fini are optional):
2284   void *reduce_init; /**< data initialization routine (two parameters) */
2285   void *reduce_fini; /**< data finalization routine */
2286   void *reduce_comb; /**< data combiner routine */
2287   kmp_taskred_flags_t flags; /**< flags for additional info from compiler */
2288 } kmp_taskred_input_t;
2289 /*!
2290 @}
2291 */
2292 
2293 template <typename T> void __kmp_assign_orig(kmp_taskred_data_t &item, T &src);
2294 template <>
2295 void __kmp_assign_orig<kmp_task_red_input_t>(kmp_taskred_data_t &item,
2296                                              kmp_task_red_input_t &src) {
2297   item.reduce_orig = NULL;
2298 }
2299 template <>
2300 void __kmp_assign_orig<kmp_taskred_input_t>(kmp_taskred_data_t &item,
2301                                             kmp_taskred_input_t &src) {
2302   if (src.reduce_orig != NULL) {
2303     item.reduce_orig = src.reduce_orig;
2304   } else {
2305     item.reduce_orig = src.reduce_shar;
2306   } // non-NULL reduce_orig means new interface used
2307 }
2308 
2309 template <typename T> void __kmp_call_init(kmp_taskred_data_t &item, size_t j);
2310 template <>
2311 void __kmp_call_init<kmp_task_red_input_t>(kmp_taskred_data_t &item,
2312                                            size_t offset) {
2313   ((void (*)(void *))item.reduce_init)((char *)(item.reduce_priv) + offset);
2314 }
2315 template <>
2316 void __kmp_call_init<kmp_taskred_input_t>(kmp_taskred_data_t &item,
2317                                           size_t offset) {
2318   ((void (*)(void *, void *))item.reduce_init)(
2319       (char *)(item.reduce_priv) + offset, item.reduce_orig);
2320 }
2321 
2322 template <typename T>
2323 void *__kmp_task_reduction_init(int gtid, int num, T *data) {
2324   __kmp_assert_valid_gtid(gtid);
2325   kmp_info_t *thread = __kmp_threads[gtid];
2326   kmp_taskgroup_t *tg = thread->th.th_current_task->td_taskgroup;
2327   kmp_uint32 nth = thread->th.th_team_nproc;
2328   kmp_taskred_data_t *arr;
2329 
2330   // check input data just in case
2331   KMP_ASSERT(tg != NULL);
2332   KMP_ASSERT(data != NULL);
2333   KMP_ASSERT(num > 0);
2334   if (nth == 1) {
2335     KA_TRACE(10, ("__kmpc_task_reduction_init: T#%d, tg %p, exiting nth=1\n",
2336                   gtid, tg));
2337     return (void *)tg;
2338   }
2339   KA_TRACE(10, ("__kmpc_task_reduction_init: T#%d, taskgroup %p, #items %d\n",
2340                 gtid, tg, num));
2341   arr = (kmp_taskred_data_t *)__kmp_thread_malloc(
2342       thread, num * sizeof(kmp_taskred_data_t));
2343   for (int i = 0; i < num; ++i) {
2344     size_t size = data[i].reduce_size - 1;
2345     // round the size up to cache line per thread-specific item
2346     size += CACHE_LINE - size % CACHE_LINE;
2347     KMP_ASSERT(data[i].reduce_comb != NULL); // combiner is mandatory
2348     arr[i].reduce_shar = data[i].reduce_shar;
2349     arr[i].reduce_size = size;
2350     arr[i].flags = data[i].flags;
2351     arr[i].reduce_comb = data[i].reduce_comb;
2352     arr[i].reduce_init = data[i].reduce_init;
2353     arr[i].reduce_fini = data[i].reduce_fini;
2354     __kmp_assign_orig<T>(arr[i], data[i]);
2355     if (!arr[i].flags.lazy_priv) {
2356       // allocate cache-line aligned block and fill it with zeros
2357       arr[i].reduce_priv = __kmp_allocate(nth * size);
2358       arr[i].reduce_pend = (char *)(arr[i].reduce_priv) + nth * size;
2359       if (arr[i].reduce_init != NULL) {
2360         // initialize all thread-specific items
2361         for (size_t j = 0; j < nth; ++j) {
2362           __kmp_call_init<T>(arr[i], j * size);
2363         }
2364       }
2365     } else {
2366       // only allocate space for pointers now,
2367       // objects will be lazily allocated/initialized if/when requested
2368       // note that __kmp_allocate zeroes the allocated memory
2369       arr[i].reduce_priv = __kmp_allocate(nth * sizeof(void *));
2370     }
2371   }
2372   tg->reduce_data = (void *)arr;
2373   tg->reduce_num_data = num;
2374   return (void *)tg;
2375 }
2376 
2377 /*!
2378 @ingroup TASKING
2379 @param gtid      Global thread ID
2380 @param num       Number of data items to reduce
2381 @param data      Array of data for reduction
2382 @return The taskgroup identifier
2383 
2384 Initialize task reduction for the taskgroup.
2385 
2386 Note: this entry supposes the optional compiler-generated initializer routine
2387 has single parameter - pointer to object to be initialized. That means
2388 the reduction either does not use omp_orig object, or the omp_orig is accessible
2389 without help of the runtime library.
2390 */
2391 void *__kmpc_task_reduction_init(int gtid, int num, void *data) {
2392   return __kmp_task_reduction_init(gtid, num, (kmp_task_red_input_t *)data);
2393 }
2394 
2395 /*!
2396 @ingroup TASKING
2397 @param gtid      Global thread ID
2398 @param num       Number of data items to reduce
2399 @param data      Array of data for reduction
2400 @return The taskgroup identifier
2401 
2402 Initialize task reduction for the taskgroup.
2403 
2404 Note: this entry supposes the optional compiler-generated initializer routine
2405 has two parameters, pointer to object to be initialized and pointer to omp_orig
2406 */
2407 void *__kmpc_taskred_init(int gtid, int num, void *data) {
2408   return __kmp_task_reduction_init(gtid, num, (kmp_taskred_input_t *)data);
2409 }
2410 
2411 // Copy task reduction data (except for shared pointers).
2412 template <typename T>
2413 void __kmp_task_reduction_init_copy(kmp_info_t *thr, int num, T *data,
2414                                     kmp_taskgroup_t *tg, void *reduce_data) {
2415   kmp_taskred_data_t *arr;
2416   KA_TRACE(20, ("__kmp_task_reduction_init_copy: Th %p, init taskgroup %p,"
2417                 " from data %p\n",
2418                 thr, tg, reduce_data));
2419   arr = (kmp_taskred_data_t *)__kmp_thread_malloc(
2420       thr, num * sizeof(kmp_taskred_data_t));
2421   // threads will share private copies, thunk routines, sizes, flags, etc.:
2422   KMP_MEMCPY(arr, reduce_data, num * sizeof(kmp_taskred_data_t));
2423   for (int i = 0; i < num; ++i) {
2424     arr[i].reduce_shar = data[i].reduce_shar; // init unique shared pointers
2425   }
2426   tg->reduce_data = (void *)arr;
2427   tg->reduce_num_data = num;
2428 }
2429 
2430 /*!
2431 @ingroup TASKING
2432 @param gtid    Global thread ID
2433 @param tskgrp  The taskgroup ID (optional)
2434 @param data    Shared location of the item
2435 @return The pointer to per-thread data
2436 
2437 Get thread-specific location of data item
2438 */
2439 void *__kmpc_task_reduction_get_th_data(int gtid, void *tskgrp, void *data) {
2440   __kmp_assert_valid_gtid(gtid);
2441   kmp_info_t *thread = __kmp_threads[gtid];
2442   kmp_int32 nth = thread->th.th_team_nproc;
2443   if (nth == 1)
2444     return data; // nothing to do
2445 
2446   kmp_taskgroup_t *tg = (kmp_taskgroup_t *)tskgrp;
2447   if (tg == NULL)
2448     tg = thread->th.th_current_task->td_taskgroup;
2449   KMP_ASSERT(tg != NULL);
2450   kmp_taskred_data_t *arr = (kmp_taskred_data_t *)(tg->reduce_data);
2451   kmp_int32 num = tg->reduce_num_data;
2452   kmp_int32 tid = thread->th.th_info.ds.ds_tid;
2453 
2454   KMP_ASSERT(data != NULL);
2455   while (tg != NULL) {
2456     for (int i = 0; i < num; ++i) {
2457       if (!arr[i].flags.lazy_priv) {
2458         if (data == arr[i].reduce_shar ||
2459             (data >= arr[i].reduce_priv && data < arr[i].reduce_pend))
2460           return (char *)(arr[i].reduce_priv) + tid * arr[i].reduce_size;
2461       } else {
2462         // check shared location first
2463         void **p_priv = (void **)(arr[i].reduce_priv);
2464         if (data == arr[i].reduce_shar)
2465           goto found;
2466         // check if we get some thread specific location as parameter
2467         for (int j = 0; j < nth; ++j)
2468           if (data == p_priv[j])
2469             goto found;
2470         continue; // not found, continue search
2471       found:
2472         if (p_priv[tid] == NULL) {
2473           // allocate thread specific object lazily
2474           p_priv[tid] = __kmp_allocate(arr[i].reduce_size);
2475           if (arr[i].reduce_init != NULL) {
2476             if (arr[i].reduce_orig != NULL) { // new interface
2477               ((void (*)(void *, void *))arr[i].reduce_init)(
2478                   p_priv[tid], arr[i].reduce_orig);
2479             } else { // old interface (single parameter)
2480               ((void (*)(void *))arr[i].reduce_init)(p_priv[tid]);
2481             }
2482           }
2483         }
2484         return p_priv[tid];
2485       }
2486     }
2487     tg = tg->parent;
2488     arr = (kmp_taskred_data_t *)(tg->reduce_data);
2489     num = tg->reduce_num_data;
2490   }
2491   KMP_ASSERT2(0, "Unknown task reduction item");
2492   return NULL; // ERROR, this line never executed
2493 }
2494 
2495 // Finalize task reduction.
2496 // Called from __kmpc_end_taskgroup()
2497 static void __kmp_task_reduction_fini(kmp_info_t *th, kmp_taskgroup_t *tg) {
2498   kmp_int32 nth = th->th.th_team_nproc;
2499   KMP_DEBUG_ASSERT(nth > 1); // should not be called if nth == 1
2500   kmp_taskred_data_t *arr = (kmp_taskred_data_t *)tg->reduce_data;
2501   kmp_int32 num = tg->reduce_num_data;
2502   for (int i = 0; i < num; ++i) {
2503     void *sh_data = arr[i].reduce_shar;
2504     void (*f_fini)(void *) = (void (*)(void *))(arr[i].reduce_fini);
2505     void (*f_comb)(void *, void *) =
2506         (void (*)(void *, void *))(arr[i].reduce_comb);
2507     if (!arr[i].flags.lazy_priv) {
2508       void *pr_data = arr[i].reduce_priv;
2509       size_t size = arr[i].reduce_size;
2510       for (int j = 0; j < nth; ++j) {
2511         void *priv_data = (char *)pr_data + j * size;
2512         f_comb(sh_data, priv_data); // combine results
2513         if (f_fini)
2514           f_fini(priv_data); // finalize if needed
2515       }
2516     } else {
2517       void **pr_data = (void **)(arr[i].reduce_priv);
2518       for (int j = 0; j < nth; ++j) {
2519         if (pr_data[j] != NULL) {
2520           f_comb(sh_data, pr_data[j]); // combine results
2521           if (f_fini)
2522             f_fini(pr_data[j]); // finalize if needed
2523           __kmp_free(pr_data[j]);
2524         }
2525       }
2526     }
2527     __kmp_free(arr[i].reduce_priv);
2528   }
2529   __kmp_thread_free(th, arr);
2530   tg->reduce_data = NULL;
2531   tg->reduce_num_data = 0;
2532 }
2533 
2534 // Cleanup task reduction data for parallel or worksharing,
2535 // do not touch task private data other threads still working with.
2536 // Called from __kmpc_end_taskgroup()
2537 static void __kmp_task_reduction_clean(kmp_info_t *th, kmp_taskgroup_t *tg) {
2538   __kmp_thread_free(th, tg->reduce_data);
2539   tg->reduce_data = NULL;
2540   tg->reduce_num_data = 0;
2541 }
2542 
2543 template <typename T>
2544 void *__kmp_task_reduction_modifier_init(ident_t *loc, int gtid, int is_ws,
2545                                          int num, T *data) {
2546   __kmp_assert_valid_gtid(gtid);
2547   kmp_info_t *thr = __kmp_threads[gtid];
2548   kmp_int32 nth = thr->th.th_team_nproc;
2549   __kmpc_taskgroup(loc, gtid); // form new taskgroup first
2550   if (nth == 1) {
2551     KA_TRACE(10,
2552              ("__kmpc_reduction_modifier_init: T#%d, tg %p, exiting nth=1\n",
2553               gtid, thr->th.th_current_task->td_taskgroup));
2554     return (void *)thr->th.th_current_task->td_taskgroup;
2555   }
2556   kmp_team_t *team = thr->th.th_team;
2557   void *reduce_data;
2558   kmp_taskgroup_t *tg;
2559   reduce_data = KMP_ATOMIC_LD_RLX(&team->t.t_tg_reduce_data[is_ws]);
2560   if (reduce_data == NULL &&
2561       __kmp_atomic_compare_store(&team->t.t_tg_reduce_data[is_ws], reduce_data,
2562                                  (void *)1)) {
2563     // single thread enters this block to initialize common reduction data
2564     KMP_DEBUG_ASSERT(reduce_data == NULL);
2565     // first initialize own data, then make a copy other threads can use
2566     tg = (kmp_taskgroup_t *)__kmp_task_reduction_init<T>(gtid, num, data);
2567     reduce_data = __kmp_thread_malloc(thr, num * sizeof(kmp_taskred_data_t));
2568     KMP_MEMCPY(reduce_data, tg->reduce_data, num * sizeof(kmp_taskred_data_t));
2569     // fini counters should be 0 at this point
2570     KMP_DEBUG_ASSERT(KMP_ATOMIC_LD_RLX(&team->t.t_tg_fini_counter[0]) == 0);
2571     KMP_DEBUG_ASSERT(KMP_ATOMIC_LD_RLX(&team->t.t_tg_fini_counter[1]) == 0);
2572     KMP_ATOMIC_ST_REL(&team->t.t_tg_reduce_data[is_ws], reduce_data);
2573   } else {
2574     while (
2575         (reduce_data = KMP_ATOMIC_LD_ACQ(&team->t.t_tg_reduce_data[is_ws])) ==
2576         (void *)1) { // wait for task reduction initialization
2577       KMP_CPU_PAUSE();
2578     }
2579     KMP_DEBUG_ASSERT(reduce_data > (void *)1); // should be valid pointer here
2580     tg = thr->th.th_current_task->td_taskgroup;
2581     __kmp_task_reduction_init_copy<T>(thr, num, data, tg, reduce_data);
2582   }
2583   return tg;
2584 }
2585 
2586 /*!
2587 @ingroup TASKING
2588 @param loc       Source location info
2589 @param gtid      Global thread ID
2590 @param is_ws     Is 1 if the reduction is for worksharing, 0 otherwise
2591 @param num       Number of data items to reduce
2592 @param data      Array of data for reduction
2593 @return The taskgroup identifier
2594 
2595 Initialize task reduction for a parallel or worksharing.
2596 
2597 Note: this entry supposes the optional compiler-generated initializer routine
2598 has single parameter - pointer to object to be initialized. That means
2599 the reduction either does not use omp_orig object, or the omp_orig is accessible
2600 without help of the runtime library.
2601 */
2602 void *__kmpc_task_reduction_modifier_init(ident_t *loc, int gtid, int is_ws,
2603                                           int num, void *data) {
2604   return __kmp_task_reduction_modifier_init(loc, gtid, is_ws, num,
2605                                             (kmp_task_red_input_t *)data);
2606 }
2607 
2608 /*!
2609 @ingroup TASKING
2610 @param loc       Source location info
2611 @param gtid      Global thread ID
2612 @param is_ws     Is 1 if the reduction is for worksharing, 0 otherwise
2613 @param num       Number of data items to reduce
2614 @param data      Array of data for reduction
2615 @return The taskgroup identifier
2616 
2617 Initialize task reduction for a parallel or worksharing.
2618 
2619 Note: this entry supposes the optional compiler-generated initializer routine
2620 has two parameters, pointer to object to be initialized and pointer to omp_orig
2621 */
2622 void *__kmpc_taskred_modifier_init(ident_t *loc, int gtid, int is_ws, int num,
2623                                    void *data) {
2624   return __kmp_task_reduction_modifier_init(loc, gtid, is_ws, num,
2625                                             (kmp_taskred_input_t *)data);
2626 }
2627 
2628 /*!
2629 @ingroup TASKING
2630 @param loc       Source location info
2631 @param gtid      Global thread ID
2632 @param is_ws     Is 1 if the reduction is for worksharing, 0 otherwise
2633 
2634 Finalize task reduction for a parallel or worksharing.
2635 */
2636 void __kmpc_task_reduction_modifier_fini(ident_t *loc, int gtid, int is_ws) {
2637   __kmpc_end_taskgroup(loc, gtid);
2638 }
2639 
2640 // __kmpc_taskgroup: Start a new taskgroup
2641 void __kmpc_taskgroup(ident_t *loc, int gtid) {
2642   __kmp_assert_valid_gtid(gtid);
2643   kmp_info_t *thread = __kmp_threads[gtid];
2644   kmp_taskdata_t *taskdata = thread->th.th_current_task;
2645   kmp_taskgroup_t *tg_new =
2646       (kmp_taskgroup_t *)__kmp_thread_malloc(thread, sizeof(kmp_taskgroup_t));
2647   KA_TRACE(10, ("__kmpc_taskgroup: T#%d loc=%p group=%p\n", gtid, loc, tg_new));
2648   KMP_ATOMIC_ST_RLX(&tg_new->count, 0);
2649   KMP_ATOMIC_ST_RLX(&tg_new->cancel_request, cancel_noreq);
2650   tg_new->parent = taskdata->td_taskgroup;
2651   tg_new->reduce_data = NULL;
2652   tg_new->reduce_num_data = 0;
2653   tg_new->gomp_data = NULL;
2654   taskdata->td_taskgroup = tg_new;
2655 
2656 #if OMPT_SUPPORT && OMPT_OPTIONAL
2657   if (UNLIKELY(ompt_enabled.ompt_callback_sync_region)) {
2658     void *codeptr = OMPT_LOAD_RETURN_ADDRESS(gtid);
2659     if (!codeptr)
2660       codeptr = OMPT_GET_RETURN_ADDRESS(0);
2661     kmp_team_t *team = thread->th.th_team;
2662     ompt_data_t my_task_data = taskdata->ompt_task_info.task_data;
2663     // FIXME: I think this is wrong for lwt!
2664     ompt_data_t my_parallel_data = team->t.ompt_team_info.parallel_data;
2665 
2666     ompt_callbacks.ompt_callback(ompt_callback_sync_region)(
2667         ompt_sync_region_taskgroup, ompt_scope_begin, &(my_parallel_data),
2668         &(my_task_data), codeptr);
2669   }
2670 #endif
2671 }
2672 
2673 // __kmpc_end_taskgroup: Wait until all tasks generated by the current task
2674 //                       and its descendants are complete
2675 void __kmpc_end_taskgroup(ident_t *loc, int gtid) {
2676   __kmp_assert_valid_gtid(gtid);
2677   kmp_info_t *thread = __kmp_threads[gtid];
2678   kmp_taskdata_t *taskdata = thread->th.th_current_task;
2679   kmp_taskgroup_t *taskgroup = taskdata->td_taskgroup;
2680   int thread_finished = FALSE;
2681 
2682 #if OMPT_SUPPORT && OMPT_OPTIONAL
2683   kmp_team_t *team;
2684   ompt_data_t my_task_data;
2685   ompt_data_t my_parallel_data;
2686   void *codeptr = nullptr;
2687   if (UNLIKELY(ompt_enabled.enabled)) {
2688     team = thread->th.th_team;
2689     my_task_data = taskdata->ompt_task_info.task_data;
2690     // FIXME: I think this is wrong for lwt!
2691     my_parallel_data = team->t.ompt_team_info.parallel_data;
2692     codeptr = OMPT_LOAD_RETURN_ADDRESS(gtid);
2693     if (!codeptr)
2694       codeptr = OMPT_GET_RETURN_ADDRESS(0);
2695   }
2696 #endif
2697 
2698   KA_TRACE(10, ("__kmpc_end_taskgroup(enter): T#%d loc=%p\n", gtid, loc));
2699   KMP_DEBUG_ASSERT(taskgroup != NULL);
2700   KMP_SET_THREAD_STATE_BLOCK(TASKGROUP);
2701 
2702   if (__kmp_tasking_mode != tskm_immediate_exec) {
2703     // mark task as waiting not on a barrier
2704     taskdata->td_taskwait_counter += 1;
2705     taskdata->td_taskwait_ident = loc;
2706     taskdata->td_taskwait_thread = gtid + 1;
2707 #if USE_ITT_BUILD
2708     // For ITT the taskgroup wait is similar to taskwait until we need to
2709     // distinguish them
2710     void *itt_sync_obj = NULL;
2711 #if USE_ITT_NOTIFY
2712     KMP_ITT_TASKWAIT_STARTING(itt_sync_obj);
2713 #endif /* USE_ITT_NOTIFY */
2714 #endif /* USE_ITT_BUILD */
2715 
2716 #if OMPT_SUPPORT && OMPT_OPTIONAL
2717     if (UNLIKELY(ompt_enabled.ompt_callback_sync_region_wait)) {
2718       ompt_callbacks.ompt_callback(ompt_callback_sync_region_wait)(
2719           ompt_sync_region_taskgroup, ompt_scope_begin, &(my_parallel_data),
2720           &(my_task_data), codeptr);
2721     }
2722 #endif
2723 
2724     if (!taskdata->td_flags.team_serial ||
2725         (thread->th.th_task_team != NULL &&
2726          (thread->th.th_task_team->tt.tt_found_proxy_tasks ||
2727           thread->th.th_task_team->tt.tt_hidden_helper_task_encountered))) {
2728       kmp_flag_32<false, false> flag(
2729           RCAST(std::atomic<kmp_uint32> *, &(taskgroup->count)), 0U);
2730       while (KMP_ATOMIC_LD_ACQ(&taskgroup->count) != 0) {
2731         flag.execute_tasks(thread, gtid, FALSE,
2732                            &thread_finished USE_ITT_BUILD_ARG(itt_sync_obj),
2733                            __kmp_task_stealing_constraint);
2734       }
2735     }
2736     taskdata->td_taskwait_thread = -taskdata->td_taskwait_thread; // end waiting
2737 
2738 #if OMPT_SUPPORT && OMPT_OPTIONAL
2739     if (UNLIKELY(ompt_enabled.ompt_callback_sync_region_wait)) {
2740       ompt_callbacks.ompt_callback(ompt_callback_sync_region_wait)(
2741           ompt_sync_region_taskgroup, ompt_scope_end, &(my_parallel_data),
2742           &(my_task_data), codeptr);
2743     }
2744 #endif
2745 
2746 #if USE_ITT_BUILD
2747     KMP_ITT_TASKWAIT_FINISHED(itt_sync_obj);
2748     KMP_FSYNC_ACQUIRED(taskdata); // acquire self - sync with descendants
2749 #endif /* USE_ITT_BUILD */
2750   }
2751   KMP_DEBUG_ASSERT(taskgroup->count == 0);
2752 
2753   if (taskgroup->reduce_data != NULL &&
2754       !taskgroup->gomp_data) { // need to reduce?
2755     int cnt;
2756     void *reduce_data;
2757     kmp_team_t *t = thread->th.th_team;
2758     kmp_taskred_data_t *arr = (kmp_taskred_data_t *)taskgroup->reduce_data;
2759     // check if <priv> data of the first reduction variable shared for the team
2760     void *priv0 = arr[0].reduce_priv;
2761     if ((reduce_data = KMP_ATOMIC_LD_ACQ(&t->t.t_tg_reduce_data[0])) != NULL &&
2762         ((kmp_taskred_data_t *)reduce_data)[0].reduce_priv == priv0) {
2763       // finishing task reduction on parallel
2764       cnt = KMP_ATOMIC_INC(&t->t.t_tg_fini_counter[0]);
2765       if (cnt == thread->th.th_team_nproc - 1) {
2766         // we are the last thread passing __kmpc_reduction_modifier_fini()
2767         // finalize task reduction:
2768         __kmp_task_reduction_fini(thread, taskgroup);
2769         // cleanup fields in the team structure:
2770         // TODO: is relaxed store enough here (whole barrier should follow)?
2771         __kmp_thread_free(thread, reduce_data);
2772         KMP_ATOMIC_ST_REL(&t->t.t_tg_reduce_data[0], NULL);
2773         KMP_ATOMIC_ST_REL(&t->t.t_tg_fini_counter[0], 0);
2774       } else {
2775         // we are not the last thread passing __kmpc_reduction_modifier_fini(),
2776         // so do not finalize reduction, just clean own copy of the data
2777         __kmp_task_reduction_clean(thread, taskgroup);
2778       }
2779     } else if ((reduce_data = KMP_ATOMIC_LD_ACQ(&t->t.t_tg_reduce_data[1])) !=
2780                    NULL &&
2781                ((kmp_taskred_data_t *)reduce_data)[0].reduce_priv == priv0) {
2782       // finishing task reduction on worksharing
2783       cnt = KMP_ATOMIC_INC(&t->t.t_tg_fini_counter[1]);
2784       if (cnt == thread->th.th_team_nproc - 1) {
2785         // we are the last thread passing __kmpc_reduction_modifier_fini()
2786         __kmp_task_reduction_fini(thread, taskgroup);
2787         // cleanup fields in team structure:
2788         // TODO: is relaxed store enough here (whole barrier should follow)?
2789         __kmp_thread_free(thread, reduce_data);
2790         KMP_ATOMIC_ST_REL(&t->t.t_tg_reduce_data[1], NULL);
2791         KMP_ATOMIC_ST_REL(&t->t.t_tg_fini_counter[1], 0);
2792       } else {
2793         // we are not the last thread passing __kmpc_reduction_modifier_fini(),
2794         // so do not finalize reduction, just clean own copy of the data
2795         __kmp_task_reduction_clean(thread, taskgroup);
2796       }
2797     } else {
2798       // finishing task reduction on taskgroup
2799       __kmp_task_reduction_fini(thread, taskgroup);
2800     }
2801   }
2802   // Restore parent taskgroup for the current task
2803   taskdata->td_taskgroup = taskgroup->parent;
2804   __kmp_thread_free(thread, taskgroup);
2805 
2806   KA_TRACE(10, ("__kmpc_end_taskgroup(exit): T#%d task %p finished waiting\n",
2807                 gtid, taskdata));
2808 
2809 #if OMPT_SUPPORT && OMPT_OPTIONAL
2810   if (UNLIKELY(ompt_enabled.ompt_callback_sync_region)) {
2811     ompt_callbacks.ompt_callback(ompt_callback_sync_region)(
2812         ompt_sync_region_taskgroup, ompt_scope_end, &(my_parallel_data),
2813         &(my_task_data), codeptr);
2814   }
2815 #endif
2816 }
2817 
2818 static kmp_task_t *__kmp_get_priority_task(kmp_int32 gtid,
2819                                            kmp_task_team_t *task_team,
2820                                            kmp_int32 is_constrained) {
2821   kmp_task_t *task = NULL;
2822   kmp_taskdata_t *taskdata;
2823   kmp_taskdata_t *current;
2824   kmp_thread_data_t *thread_data;
2825   int ntasks = task_team->tt.tt_num_task_pri;
2826   if (ntasks == 0) {
2827     KA_TRACE(
2828         20, ("__kmp_get_priority_task(exit #1): T#%d No tasks to get\n", gtid));
2829     return NULL;
2830   }
2831   do {
2832     // decrement num_tasks to "reserve" one task to get for execution
2833     if (__kmp_atomic_compare_store(&task_team->tt.tt_num_task_pri, ntasks,
2834                                    ntasks - 1))
2835       break;
2836   } while (ntasks > 0);
2837   if (ntasks == 0) {
2838     KA_TRACE(20, ("__kmp_get_priority_task(exit #2): T#%d No tasks to get\n",
2839                   __kmp_get_gtid()));
2840     return NULL;
2841   }
2842   // We got a "ticket" to get a "reserved" priority task
2843   int deque_ntasks;
2844   kmp_task_pri_t *list = task_team->tt.tt_task_pri_list;
2845   do {
2846     KMP_ASSERT(list != NULL);
2847     thread_data = &list->td;
2848     __kmp_acquire_bootstrap_lock(&thread_data->td.td_deque_lock);
2849     deque_ntasks = thread_data->td.td_deque_ntasks;
2850     if (deque_ntasks == 0) {
2851       __kmp_release_bootstrap_lock(&thread_data->td.td_deque_lock);
2852       KA_TRACE(20, ("__kmp_get_priority_task: T#%d No tasks to get from %p\n",
2853                     __kmp_get_gtid(), thread_data));
2854       list = list->next;
2855     }
2856   } while (deque_ntasks == 0);
2857   KMP_DEBUG_ASSERT(deque_ntasks);
2858   int target = thread_data->td.td_deque_head;
2859   current = __kmp_threads[gtid]->th.th_current_task;
2860   taskdata = thread_data->td.td_deque[target];
2861   if (__kmp_task_is_allowed(gtid, is_constrained, taskdata, current)) {
2862     // Bump head pointer and Wrap.
2863     thread_data->td.td_deque_head =
2864         (target + 1) & TASK_DEQUE_MASK(thread_data->td);
2865   } else {
2866     if (!task_team->tt.tt_untied_task_encountered) {
2867       // The TSC does not allow to steal victim task
2868       __kmp_release_bootstrap_lock(&thread_data->td.td_deque_lock);
2869       KA_TRACE(20, ("__kmp_get_priority_task(exit #3): T#%d could not get task "
2870                     "from %p: task_team=%p ntasks=%d head=%u tail=%u\n",
2871                     gtid, thread_data, task_team, deque_ntasks, target,
2872                     thread_data->td.td_deque_tail));
2873       task_team->tt.tt_num_task_pri++; // atomic inc, restore value
2874       return NULL;
2875     }
2876     int i;
2877     // walk through the deque trying to steal any task
2878     taskdata = NULL;
2879     for (i = 1; i < deque_ntasks; ++i) {
2880       target = (target + 1) & TASK_DEQUE_MASK(thread_data->td);
2881       taskdata = thread_data->td.td_deque[target];
2882       if (__kmp_task_is_allowed(gtid, is_constrained, taskdata, current)) {
2883         break; // found task to execute
2884       } else {
2885         taskdata = NULL;
2886       }
2887     }
2888     if (taskdata == NULL) {
2889       // No appropriate candidate found to execute
2890       __kmp_release_bootstrap_lock(&thread_data->td.td_deque_lock);
2891       KA_TRACE(
2892           10, ("__kmp_get_priority_task(exit #4): T#%d could not get task from "
2893                "%p: task_team=%p ntasks=%d head=%u tail=%u\n",
2894                gtid, thread_data, task_team, deque_ntasks,
2895                thread_data->td.td_deque_head, thread_data->td.td_deque_tail));
2896       task_team->tt.tt_num_task_pri++; // atomic inc, restore value
2897       return NULL;
2898     }
2899     int prev = target;
2900     for (i = i + 1; i < deque_ntasks; ++i) {
2901       // shift remaining tasks in the deque left by 1
2902       target = (target + 1) & TASK_DEQUE_MASK(thread_data->td);
2903       thread_data->td.td_deque[prev] = thread_data->td.td_deque[target];
2904       prev = target;
2905     }
2906     KMP_DEBUG_ASSERT(
2907         thread_data->td.td_deque_tail ==
2908         (kmp_uint32)((target + 1) & TASK_DEQUE_MASK(thread_data->td)));
2909     thread_data->td.td_deque_tail = target; // tail -= 1 (wrapped))
2910   }
2911   thread_data->td.td_deque_ntasks = deque_ntasks - 1;
2912   __kmp_release_bootstrap_lock(&thread_data->td.td_deque_lock);
2913   task = KMP_TASKDATA_TO_TASK(taskdata);
2914   return task;
2915 }
2916 
2917 // __kmp_remove_my_task: remove a task from my own deque
2918 static kmp_task_t *__kmp_remove_my_task(kmp_info_t *thread, kmp_int32 gtid,
2919                                         kmp_task_team_t *task_team,
2920                                         kmp_int32 is_constrained) {
2921   kmp_task_t *task;
2922   kmp_taskdata_t *taskdata;
2923   kmp_thread_data_t *thread_data;
2924   kmp_uint32 tail;
2925 
2926   KMP_DEBUG_ASSERT(__kmp_tasking_mode != tskm_immediate_exec);
2927   KMP_DEBUG_ASSERT(task_team->tt.tt_threads_data !=
2928                    NULL); // Caller should check this condition
2929 
2930   thread_data = &task_team->tt.tt_threads_data[__kmp_tid_from_gtid(gtid)];
2931 
2932   KA_TRACE(10, ("__kmp_remove_my_task(enter): T#%d ntasks=%d head=%u tail=%u\n",
2933                 gtid, thread_data->td.td_deque_ntasks,
2934                 thread_data->td.td_deque_head, thread_data->td.td_deque_tail));
2935 
2936   if (TCR_4(thread_data->td.td_deque_ntasks) == 0) {
2937     KA_TRACE(10,
2938              ("__kmp_remove_my_task(exit #1): T#%d No tasks to remove: "
2939               "ntasks=%d head=%u tail=%u\n",
2940               gtid, thread_data->td.td_deque_ntasks,
2941               thread_data->td.td_deque_head, thread_data->td.td_deque_tail));
2942     return NULL;
2943   }
2944 
2945   __kmp_acquire_bootstrap_lock(&thread_data->td.td_deque_lock);
2946 
2947   if (TCR_4(thread_data->td.td_deque_ntasks) == 0) {
2948     __kmp_release_bootstrap_lock(&thread_data->td.td_deque_lock);
2949     KA_TRACE(10,
2950              ("__kmp_remove_my_task(exit #2): T#%d No tasks to remove: "
2951               "ntasks=%d head=%u tail=%u\n",
2952               gtid, thread_data->td.td_deque_ntasks,
2953               thread_data->td.td_deque_head, thread_data->td.td_deque_tail));
2954     return NULL;
2955   }
2956 
2957   tail = (thread_data->td.td_deque_tail - 1) &
2958          TASK_DEQUE_MASK(thread_data->td); // Wrap index.
2959   taskdata = thread_data->td.td_deque[tail];
2960 
2961   if (!__kmp_task_is_allowed(gtid, is_constrained, taskdata,
2962                              thread->th.th_current_task)) {
2963     // The TSC does not allow to steal victim task
2964     __kmp_release_bootstrap_lock(&thread_data->td.td_deque_lock);
2965     KA_TRACE(10,
2966              ("__kmp_remove_my_task(exit #3): T#%d TSC blocks tail task: "
2967               "ntasks=%d head=%u tail=%u\n",
2968               gtid, thread_data->td.td_deque_ntasks,
2969               thread_data->td.td_deque_head, thread_data->td.td_deque_tail));
2970     return NULL;
2971   }
2972 
2973   thread_data->td.td_deque_tail = tail;
2974   TCW_4(thread_data->td.td_deque_ntasks, thread_data->td.td_deque_ntasks - 1);
2975 
2976   __kmp_release_bootstrap_lock(&thread_data->td.td_deque_lock);
2977 
2978   KA_TRACE(10, ("__kmp_remove_my_task(exit #4): T#%d task %p removed: "
2979                 "ntasks=%d head=%u tail=%u\n",
2980                 gtid, taskdata, thread_data->td.td_deque_ntasks,
2981                 thread_data->td.td_deque_head, thread_data->td.td_deque_tail));
2982 
2983   task = KMP_TASKDATA_TO_TASK(taskdata);
2984   return task;
2985 }
2986 
2987 // __kmp_steal_task: remove a task from another thread's deque
2988 // Assume that calling thread has already checked existence of
2989 // task_team thread_data before calling this routine.
2990 static kmp_task_t *__kmp_steal_task(kmp_info_t *victim_thr, kmp_int32 gtid,
2991                                     kmp_task_team_t *task_team,
2992                                     std::atomic<kmp_int32> *unfinished_threads,
2993                                     int *thread_finished,
2994                                     kmp_int32 is_constrained) {
2995   kmp_task_t *task;
2996   kmp_taskdata_t *taskdata;
2997   kmp_taskdata_t *current;
2998   kmp_thread_data_t *victim_td, *threads_data;
2999   kmp_int32 target;
3000   kmp_int32 victim_tid;
3001 
3002   KMP_DEBUG_ASSERT(__kmp_tasking_mode != tskm_immediate_exec);
3003 
3004   threads_data = task_team->tt.tt_threads_data;
3005   KMP_DEBUG_ASSERT(threads_data != NULL); // Caller should check this condition
3006 
3007   victim_tid = victim_thr->th.th_info.ds.ds_tid;
3008   victim_td = &threads_data[victim_tid];
3009 
3010   KA_TRACE(10, ("__kmp_steal_task(enter): T#%d try to steal from T#%d: "
3011                 "task_team=%p ntasks=%d head=%u tail=%u\n",
3012                 gtid, __kmp_gtid_from_thread(victim_thr), task_team,
3013                 victim_td->td.td_deque_ntasks, victim_td->td.td_deque_head,
3014                 victim_td->td.td_deque_tail));
3015 
3016   if (TCR_4(victim_td->td.td_deque_ntasks) == 0) {
3017     KA_TRACE(10, ("__kmp_steal_task(exit #1): T#%d could not steal from T#%d: "
3018                   "task_team=%p ntasks=%d head=%u tail=%u\n",
3019                   gtid, __kmp_gtid_from_thread(victim_thr), task_team,
3020                   victim_td->td.td_deque_ntasks, victim_td->td.td_deque_head,
3021                   victim_td->td.td_deque_tail));
3022     return NULL;
3023   }
3024 
3025   __kmp_acquire_bootstrap_lock(&victim_td->td.td_deque_lock);
3026 
3027   int ntasks = TCR_4(victim_td->td.td_deque_ntasks);
3028   // Check again after we acquire the lock
3029   if (ntasks == 0) {
3030     __kmp_release_bootstrap_lock(&victim_td->td.td_deque_lock);
3031     KA_TRACE(10, ("__kmp_steal_task(exit #2): T#%d could not steal from T#%d: "
3032                   "task_team=%p ntasks=%d head=%u tail=%u\n",
3033                   gtid, __kmp_gtid_from_thread(victim_thr), task_team, ntasks,
3034                   victim_td->td.td_deque_head, victim_td->td.td_deque_tail));
3035     return NULL;
3036   }
3037 
3038   KMP_DEBUG_ASSERT(victim_td->td.td_deque != NULL);
3039   current = __kmp_threads[gtid]->th.th_current_task;
3040   taskdata = victim_td->td.td_deque[victim_td->td.td_deque_head];
3041   if (__kmp_task_is_allowed(gtid, is_constrained, taskdata, current)) {
3042     // Bump head pointer and Wrap.
3043     victim_td->td.td_deque_head =
3044         (victim_td->td.td_deque_head + 1) & TASK_DEQUE_MASK(victim_td->td);
3045   } else {
3046     if (!task_team->tt.tt_untied_task_encountered) {
3047       // The TSC does not allow to steal victim task
3048       __kmp_release_bootstrap_lock(&victim_td->td.td_deque_lock);
3049       KA_TRACE(10, ("__kmp_steal_task(exit #3): T#%d could not steal from "
3050                     "T#%d: task_team=%p ntasks=%d head=%u tail=%u\n",
3051                     gtid, __kmp_gtid_from_thread(victim_thr), task_team, ntasks,
3052                     victim_td->td.td_deque_head, victim_td->td.td_deque_tail));
3053       return NULL;
3054     }
3055     int i;
3056     // walk through victim's deque trying to steal any task
3057     target = victim_td->td.td_deque_head;
3058     taskdata = NULL;
3059     for (i = 1; i < ntasks; ++i) {
3060       target = (target + 1) & TASK_DEQUE_MASK(victim_td->td);
3061       taskdata = victim_td->td.td_deque[target];
3062       if (__kmp_task_is_allowed(gtid, is_constrained, taskdata, current)) {
3063         break; // found victim task
3064       } else {
3065         taskdata = NULL;
3066       }
3067     }
3068     if (taskdata == NULL) {
3069       // No appropriate candidate to steal found
3070       __kmp_release_bootstrap_lock(&victim_td->td.td_deque_lock);
3071       KA_TRACE(10, ("__kmp_steal_task(exit #4): T#%d could not steal from "
3072                     "T#%d: task_team=%p ntasks=%d head=%u tail=%u\n",
3073                     gtid, __kmp_gtid_from_thread(victim_thr), task_team, ntasks,
3074                     victim_td->td.td_deque_head, victim_td->td.td_deque_tail));
3075       return NULL;
3076     }
3077     int prev = target;
3078     for (i = i + 1; i < ntasks; ++i) {
3079       // shift remaining tasks in the deque left by 1
3080       target = (target + 1) & TASK_DEQUE_MASK(victim_td->td);
3081       victim_td->td.td_deque[prev] = victim_td->td.td_deque[target];
3082       prev = target;
3083     }
3084     KMP_DEBUG_ASSERT(
3085         victim_td->td.td_deque_tail ==
3086         (kmp_uint32)((target + 1) & TASK_DEQUE_MASK(victim_td->td)));
3087     victim_td->td.td_deque_tail = target; // tail -= 1 (wrapped))
3088   }
3089   if (*thread_finished) {
3090     // We need to un-mark this victim as a finished victim.  This must be done
3091     // before releasing the lock, or else other threads (starting with the
3092     // primary thread victim) might be prematurely released from the barrier!!!
3093 #if KMP_DEBUG
3094     kmp_int32 count =
3095 #endif
3096         KMP_ATOMIC_INC(unfinished_threads);
3097     KA_TRACE(
3098         20,
3099         ("__kmp_steal_task: T#%d inc unfinished_threads to %d: task_team=%p\n",
3100          gtid, count + 1, task_team));
3101     *thread_finished = FALSE;
3102   }
3103   TCW_4(victim_td->td.td_deque_ntasks, ntasks - 1);
3104 
3105   __kmp_release_bootstrap_lock(&victim_td->td.td_deque_lock);
3106 
3107   KMP_COUNT_BLOCK(TASK_stolen);
3108   KA_TRACE(10,
3109            ("__kmp_steal_task(exit #5): T#%d stole task %p from T#%d: "
3110             "task_team=%p ntasks=%d head=%u tail=%u\n",
3111             gtid, taskdata, __kmp_gtid_from_thread(victim_thr), task_team,
3112             ntasks, victim_td->td.td_deque_head, victim_td->td.td_deque_tail));
3113 
3114   task = KMP_TASKDATA_TO_TASK(taskdata);
3115   return task;
3116 }
3117 
3118 // __kmp_execute_tasks_template: Choose and execute tasks until either the
3119 // condition is statisfied (return true) or there are none left (return false).
3120 //
3121 // final_spin is TRUE if this is the spin at the release barrier.
3122 // thread_finished indicates whether the thread is finished executing all
3123 // the tasks it has on its deque, and is at the release barrier.
3124 // spinner is the location on which to spin.
3125 // spinner == NULL means only execute a single task and return.
3126 // checker is the value to check to terminate the spin.
3127 template <class C>
3128 static inline int __kmp_execute_tasks_template(
3129     kmp_info_t *thread, kmp_int32 gtid, C *flag, int final_spin,
3130     int *thread_finished USE_ITT_BUILD_ARG(void *itt_sync_obj),
3131     kmp_int32 is_constrained) {
3132   kmp_task_team_t *task_team = thread->th.th_task_team;
3133   kmp_thread_data_t *threads_data;
3134   kmp_task_t *task;
3135   kmp_info_t *other_thread;
3136   kmp_taskdata_t *current_task = thread->th.th_current_task;
3137   std::atomic<kmp_int32> *unfinished_threads;
3138   kmp_int32 nthreads, victim_tid = -2, use_own_tasks = 1, new_victim = 0,
3139                       tid = thread->th.th_info.ds.ds_tid;
3140 
3141   KMP_DEBUG_ASSERT(__kmp_tasking_mode != tskm_immediate_exec);
3142   KMP_DEBUG_ASSERT(thread == __kmp_threads[gtid]);
3143 
3144   if (task_team == NULL || current_task == NULL)
3145     return FALSE;
3146 
3147   KA_TRACE(15, ("__kmp_execute_tasks_template(enter): T#%d final_spin=%d "
3148                 "*thread_finished=%d\n",
3149                 gtid, final_spin, *thread_finished));
3150 
3151   thread->th.th_reap_state = KMP_NOT_SAFE_TO_REAP;
3152   threads_data = (kmp_thread_data_t *)TCR_PTR(task_team->tt.tt_threads_data);
3153 
3154   KMP_DEBUG_ASSERT(threads_data != NULL);
3155 
3156   nthreads = task_team->tt.tt_nproc;
3157   unfinished_threads = &(task_team->tt.tt_unfinished_threads);
3158   KMP_DEBUG_ASSERT(nthreads > 1 || task_team->tt.tt_found_proxy_tasks ||
3159                    task_team->tt.tt_hidden_helper_task_encountered);
3160   KMP_DEBUG_ASSERT(*unfinished_threads >= 0);
3161 
3162   while (1) { // Outer loop keeps trying to find tasks in case of single thread
3163     // getting tasks from target constructs
3164     while (1) { // Inner loop to find a task and execute it
3165       task = NULL;
3166       if (task_team->tt.tt_num_task_pri) { // get priority task first
3167         task = __kmp_get_priority_task(gtid, task_team, is_constrained);
3168       }
3169       if (task == NULL && use_own_tasks) { // check own queue next
3170         task = __kmp_remove_my_task(thread, gtid, task_team, is_constrained);
3171       }
3172       if ((task == NULL) && (nthreads > 1)) { // Steal a task finally
3173         int asleep = 1;
3174         use_own_tasks = 0;
3175         // Try to steal from the last place I stole from successfully.
3176         if (victim_tid == -2) { // haven't stolen anything yet
3177           victim_tid = threads_data[tid].td.td_deque_last_stolen;
3178           if (victim_tid !=
3179               -1) // if we have a last stolen from victim, get the thread
3180             other_thread = threads_data[victim_tid].td.td_thr;
3181         }
3182         if (victim_tid != -1) { // found last victim
3183           asleep = 0;
3184         } else if (!new_victim) { // no recent steals and we haven't already
3185           // used a new victim; select a random thread
3186           do { // Find a different thread to steal work from.
3187             // Pick a random thread. Initial plan was to cycle through all the
3188             // threads, and only return if we tried to steal from every thread,
3189             // and failed.  Arch says that's not such a great idea.
3190             victim_tid = __kmp_get_random(thread) % (nthreads - 1);
3191             if (victim_tid >= tid) {
3192               ++victim_tid; // Adjusts random distribution to exclude self
3193             }
3194             // Found a potential victim
3195             other_thread = threads_data[victim_tid].td.td_thr;
3196             // There is a slight chance that __kmp_enable_tasking() did not wake
3197             // up all threads waiting at the barrier.  If victim is sleeping,
3198             // then wake it up. Since we were going to pay the cache miss
3199             // penalty for referencing another thread's kmp_info_t struct
3200             // anyway,
3201             // the check shouldn't cost too much performance at this point. In
3202             // extra barrier mode, tasks do not sleep at the separate tasking
3203             // barrier, so this isn't a problem.
3204             asleep = 0;
3205             if ((__kmp_tasking_mode == tskm_task_teams) &&
3206                 (__kmp_dflt_blocktime != KMP_MAX_BLOCKTIME) &&
3207                 (TCR_PTR(CCAST(void *, other_thread->th.th_sleep_loc)) !=
3208                  NULL)) {
3209               asleep = 1;
3210               __kmp_null_resume_wrapper(other_thread);
3211               // A sleeping thread should not have any tasks on it's queue.
3212               // There is a slight possibility that it resumes, steals a task
3213               // from another thread, which spawns more tasks, all in the time
3214               // that it takes this thread to check => don't write an assertion
3215               // that the victim's queue is empty.  Try stealing from a
3216               // different thread.
3217             }
3218           } while (asleep);
3219         }
3220 
3221         if (!asleep) {
3222           // We have a victim to try to steal from
3223           task = __kmp_steal_task(other_thread, gtid, task_team,
3224                                   unfinished_threads, thread_finished,
3225                                   is_constrained);
3226         }
3227         if (task != NULL) { // set last stolen to victim
3228           if (threads_data[tid].td.td_deque_last_stolen != victim_tid) {
3229             threads_data[tid].td.td_deque_last_stolen = victim_tid;
3230             // The pre-refactored code did not try more than 1 successful new
3231             // vicitm, unless the last one generated more local tasks;
3232             // new_victim keeps track of this
3233             new_victim = 1;
3234           }
3235         } else { // No tasks found; unset last_stolen
3236           KMP_CHECK_UPDATE(threads_data[tid].td.td_deque_last_stolen, -1);
3237           victim_tid = -2; // no successful victim found
3238         }
3239       }
3240 
3241       if (task == NULL)
3242         break; // break out of tasking loop
3243 
3244 // Found a task; execute it
3245 #if USE_ITT_BUILD && USE_ITT_NOTIFY
3246       if (__itt_sync_create_ptr || KMP_ITT_DEBUG) {
3247         if (itt_sync_obj == NULL) { // we are at fork barrier where we could not
3248           // get the object reliably
3249           itt_sync_obj = __kmp_itt_barrier_object(gtid, bs_forkjoin_barrier);
3250         }
3251         __kmp_itt_task_starting(itt_sync_obj);
3252       }
3253 #endif /* USE_ITT_BUILD && USE_ITT_NOTIFY */
3254       __kmp_invoke_task(gtid, task, current_task);
3255 #if USE_ITT_BUILD
3256       if (itt_sync_obj != NULL)
3257         __kmp_itt_task_finished(itt_sync_obj);
3258 #endif /* USE_ITT_BUILD */
3259       // If this thread is only partway through the barrier and the condition is
3260       // met, then return now, so that the barrier gather/release pattern can
3261       // proceed. If this thread is in the last spin loop in the barrier,
3262       // waiting to be released, we know that the termination condition will not
3263       // be satisfied, so don't waste any cycles checking it.
3264       if (flag == NULL || (!final_spin && flag->done_check())) {
3265         KA_TRACE(
3266             15,
3267             ("__kmp_execute_tasks_template: T#%d spin condition satisfied\n",
3268              gtid));
3269         return TRUE;
3270       }
3271       if (thread->th.th_task_team == NULL) {
3272         break;
3273       }
3274       KMP_YIELD(__kmp_library == library_throughput); // Yield before next task
3275       // If execution of a stolen task results in more tasks being placed on our
3276       // run queue, reset use_own_tasks
3277       if (!use_own_tasks && TCR_4(threads_data[tid].td.td_deque_ntasks) != 0) {
3278         KA_TRACE(20, ("__kmp_execute_tasks_template: T#%d stolen task spawned "
3279                       "other tasks, restart\n",
3280                       gtid));
3281         use_own_tasks = 1;
3282         new_victim = 0;
3283       }
3284     }
3285 
3286     // The task source has been exhausted. If in final spin loop of barrier,
3287     // check if termination condition is satisfied. The work queue may be empty
3288     // but there might be proxy tasks still executing.
3289     if (final_spin &&
3290         KMP_ATOMIC_LD_ACQ(&current_task->td_incomplete_child_tasks) == 0) {
3291       // First, decrement the #unfinished threads, if that has not already been
3292       // done.  This decrement might be to the spin location, and result in the
3293       // termination condition being satisfied.
3294       if (!*thread_finished) {
3295 #if KMP_DEBUG
3296         kmp_int32 count = -1 +
3297 #endif
3298             KMP_ATOMIC_DEC(unfinished_threads);
3299         KA_TRACE(20, ("__kmp_execute_tasks_template: T#%d dec "
3300                       "unfinished_threads to %d task_team=%p\n",
3301                       gtid, count, task_team));
3302         *thread_finished = TRUE;
3303       }
3304 
3305       // It is now unsafe to reference thread->th.th_team !!!
3306       // Decrementing task_team->tt.tt_unfinished_threads can allow the primary
3307       // thread to pass through the barrier, where it might reset each thread's
3308       // th.th_team field for the next parallel region. If we can steal more
3309       // work, we know that this has not happened yet.
3310       if (flag != NULL && flag->done_check()) {
3311         KA_TRACE(
3312             15,
3313             ("__kmp_execute_tasks_template: T#%d spin condition satisfied\n",
3314              gtid));
3315         return TRUE;
3316       }
3317     }
3318 
3319     // If this thread's task team is NULL, primary thread has recognized that
3320     // there are no more tasks; bail out
3321     if (thread->th.th_task_team == NULL) {
3322       KA_TRACE(15,
3323                ("__kmp_execute_tasks_template: T#%d no more tasks\n", gtid));
3324       return FALSE;
3325     }
3326 
3327     // Check the flag again to see if it has already done in case to be trapped
3328     // into infinite loop when a if0 task depends on a hidden helper task
3329     // outside any parallel region. Detached tasks are not impacted in this case
3330     // because the only thread executing this function has to execute the proxy
3331     // task so it is in another code path that has the same check.
3332     if (flag == NULL || (!final_spin && flag->done_check())) {
3333       KA_TRACE(15,
3334                ("__kmp_execute_tasks_template: T#%d spin condition satisfied\n",
3335                 gtid));
3336       return TRUE;
3337     }
3338 
3339     // We could be getting tasks from target constructs; if this is the only
3340     // thread, keep trying to execute tasks from own queue
3341     if (nthreads == 1 &&
3342         KMP_ATOMIC_LD_ACQ(&current_task->td_incomplete_child_tasks))
3343       use_own_tasks = 1;
3344     else {
3345       KA_TRACE(15,
3346                ("__kmp_execute_tasks_template: T#%d can't find work\n", gtid));
3347       return FALSE;
3348     }
3349   }
3350 }
3351 
3352 template <bool C, bool S>
3353 int __kmp_execute_tasks_32(
3354     kmp_info_t *thread, kmp_int32 gtid, kmp_flag_32<C, S> *flag, int final_spin,
3355     int *thread_finished USE_ITT_BUILD_ARG(void *itt_sync_obj),
3356     kmp_int32 is_constrained) {
3357   return __kmp_execute_tasks_template(
3358       thread, gtid, flag, final_spin,
3359       thread_finished USE_ITT_BUILD_ARG(itt_sync_obj), is_constrained);
3360 }
3361 
3362 template <bool C, bool S>
3363 int __kmp_execute_tasks_64(
3364     kmp_info_t *thread, kmp_int32 gtid, kmp_flag_64<C, S> *flag, int final_spin,
3365     int *thread_finished USE_ITT_BUILD_ARG(void *itt_sync_obj),
3366     kmp_int32 is_constrained) {
3367   return __kmp_execute_tasks_template(
3368       thread, gtid, flag, final_spin,
3369       thread_finished USE_ITT_BUILD_ARG(itt_sync_obj), is_constrained);
3370 }
3371 
3372 template <bool C, bool S>
3373 int __kmp_atomic_execute_tasks_64(
3374     kmp_info_t *thread, kmp_int32 gtid, kmp_atomic_flag_64<C, S> *flag,
3375     int final_spin, int *thread_finished USE_ITT_BUILD_ARG(void *itt_sync_obj),
3376     kmp_int32 is_constrained) {
3377   return __kmp_execute_tasks_template(
3378       thread, gtid, flag, final_spin,
3379       thread_finished USE_ITT_BUILD_ARG(itt_sync_obj), is_constrained);
3380 }
3381 
3382 int __kmp_execute_tasks_oncore(
3383     kmp_info_t *thread, kmp_int32 gtid, kmp_flag_oncore *flag, int final_spin,
3384     int *thread_finished USE_ITT_BUILD_ARG(void *itt_sync_obj),
3385     kmp_int32 is_constrained) {
3386   return __kmp_execute_tasks_template(
3387       thread, gtid, flag, final_spin,
3388       thread_finished USE_ITT_BUILD_ARG(itt_sync_obj), is_constrained);
3389 }
3390 
3391 template int
3392 __kmp_execute_tasks_32<false, false>(kmp_info_t *, kmp_int32,
3393                                      kmp_flag_32<false, false> *, int,
3394                                      int *USE_ITT_BUILD_ARG(void *), kmp_int32);
3395 
3396 template int __kmp_execute_tasks_64<false, true>(kmp_info_t *, kmp_int32,
3397                                                  kmp_flag_64<false, true> *,
3398                                                  int,
3399                                                  int *USE_ITT_BUILD_ARG(void *),
3400                                                  kmp_int32);
3401 
3402 template int __kmp_execute_tasks_64<true, false>(kmp_info_t *, kmp_int32,
3403                                                  kmp_flag_64<true, false> *,
3404                                                  int,
3405                                                  int *USE_ITT_BUILD_ARG(void *),
3406                                                  kmp_int32);
3407 
3408 template int __kmp_atomic_execute_tasks_64<false, true>(
3409     kmp_info_t *, kmp_int32, kmp_atomic_flag_64<false, true> *, int,
3410     int *USE_ITT_BUILD_ARG(void *), kmp_int32);
3411 
3412 template int __kmp_atomic_execute_tasks_64<true, false>(
3413     kmp_info_t *, kmp_int32, kmp_atomic_flag_64<true, false> *, int,
3414     int *USE_ITT_BUILD_ARG(void *), kmp_int32);
3415 
3416 // __kmp_enable_tasking: Allocate task team and resume threads sleeping at the
3417 // next barrier so they can assist in executing enqueued tasks.
3418 // First thread in allocates the task team atomically.
3419 static void __kmp_enable_tasking(kmp_task_team_t *task_team,
3420                                  kmp_info_t *this_thr) {
3421   kmp_thread_data_t *threads_data;
3422   int nthreads, i, is_init_thread;
3423 
3424   KA_TRACE(10, ("__kmp_enable_tasking(enter): T#%d\n",
3425                 __kmp_gtid_from_thread(this_thr)));
3426 
3427   KMP_DEBUG_ASSERT(task_team != NULL);
3428   KMP_DEBUG_ASSERT(this_thr->th.th_team != NULL);
3429 
3430   nthreads = task_team->tt.tt_nproc;
3431   KMP_DEBUG_ASSERT(nthreads > 0);
3432   KMP_DEBUG_ASSERT(nthreads == this_thr->th.th_team->t.t_nproc);
3433 
3434   // Allocate or increase the size of threads_data if necessary
3435   is_init_thread = __kmp_realloc_task_threads_data(this_thr, task_team);
3436 
3437   if (!is_init_thread) {
3438     // Some other thread already set up the array.
3439     KA_TRACE(
3440         20,
3441         ("__kmp_enable_tasking(exit): T#%d: threads array already set up.\n",
3442          __kmp_gtid_from_thread(this_thr)));
3443     return;
3444   }
3445   threads_data = (kmp_thread_data_t *)TCR_PTR(task_team->tt.tt_threads_data);
3446   KMP_DEBUG_ASSERT(threads_data != NULL);
3447 
3448   if (__kmp_tasking_mode == tskm_task_teams &&
3449       (__kmp_dflt_blocktime != KMP_MAX_BLOCKTIME)) {
3450     // Release any threads sleeping at the barrier, so that they can steal
3451     // tasks and execute them.  In extra barrier mode, tasks do not sleep
3452     // at the separate tasking barrier, so this isn't a problem.
3453     for (i = 0; i < nthreads; i++) {
3454       void *sleep_loc;
3455       kmp_info_t *thread = threads_data[i].td.td_thr;
3456 
3457       if (i == this_thr->th.th_info.ds.ds_tid) {
3458         continue;
3459       }
3460       // Since we haven't locked the thread's suspend mutex lock at this
3461       // point, there is a small window where a thread might be putting
3462       // itself to sleep, but hasn't set the th_sleep_loc field yet.
3463       // To work around this, __kmp_execute_tasks_template() periodically checks
3464       // see if other threads are sleeping (using the same random mechanism that
3465       // is used for task stealing) and awakens them if they are.
3466       if ((sleep_loc = TCR_PTR(CCAST(void *, thread->th.th_sleep_loc))) !=
3467           NULL) {
3468         KF_TRACE(50, ("__kmp_enable_tasking: T#%d waking up thread T#%d\n",
3469                       __kmp_gtid_from_thread(this_thr),
3470                       __kmp_gtid_from_thread(thread)));
3471         __kmp_null_resume_wrapper(thread);
3472       } else {
3473         KF_TRACE(50, ("__kmp_enable_tasking: T#%d don't wake up thread T#%d\n",
3474                       __kmp_gtid_from_thread(this_thr),
3475                       __kmp_gtid_from_thread(thread)));
3476       }
3477     }
3478   }
3479 
3480   KA_TRACE(10, ("__kmp_enable_tasking(exit): T#%d\n",
3481                 __kmp_gtid_from_thread(this_thr)));
3482 }
3483 
3484 /* // TODO: Check the comment consistency
3485  * Utility routines for "task teams".  A task team (kmp_task_t) is kind of
3486  * like a shadow of the kmp_team_t data struct, with a different lifetime.
3487  * After a child * thread checks into a barrier and calls __kmp_release() from
3488  * the particular variant of __kmp_<barrier_kind>_barrier_gather(), it can no
3489  * longer assume that the kmp_team_t structure is intact (at any moment, the
3490  * primary thread may exit the barrier code and free the team data structure,
3491  * and return the threads to the thread pool).
3492  *
3493  * This does not work with the tasking code, as the thread is still
3494  * expected to participate in the execution of any tasks that may have been
3495  * spawned my a member of the team, and the thread still needs access to all
3496  * to each thread in the team, so that it can steal work from it.
3497  *
3498  * Enter the existence of the kmp_task_team_t struct.  It employs a reference
3499  * counting mechanism, and is allocated by the primary thread before calling
3500  * __kmp_<barrier_kind>_release, and then is release by the last thread to
3501  * exit __kmp_<barrier_kind>_release at the next barrier.  I.e. the lifetimes
3502  * of the kmp_task_team_t structs for consecutive barriers can overlap
3503  * (and will, unless the primary thread is the last thread to exit the barrier
3504  * release phase, which is not typical). The existence of such a struct is
3505  * useful outside the context of tasking.
3506  *
3507  * We currently use the existence of the threads array as an indicator that
3508  * tasks were spawned since the last barrier.  If the structure is to be
3509  * useful outside the context of tasking, then this will have to change, but
3510  * not setting the field minimizes the performance impact of tasking on
3511  * barriers, when no explicit tasks were spawned (pushed, actually).
3512  */
3513 
3514 static kmp_task_team_t *__kmp_free_task_teams =
3515     NULL; // Free list for task_team data structures
3516 // Lock for task team data structures
3517 kmp_bootstrap_lock_t __kmp_task_team_lock =
3518     KMP_BOOTSTRAP_LOCK_INITIALIZER(__kmp_task_team_lock);
3519 
3520 // __kmp_alloc_task_deque:
3521 // Allocates a task deque for a particular thread, and initialize the necessary
3522 // data structures relating to the deque.  This only happens once per thread
3523 // per task team since task teams are recycled. No lock is needed during
3524 // allocation since each thread allocates its own deque.
3525 static void __kmp_alloc_task_deque(kmp_info_t *thread,
3526                                    kmp_thread_data_t *thread_data) {
3527   __kmp_init_bootstrap_lock(&thread_data->td.td_deque_lock);
3528   KMP_DEBUG_ASSERT(thread_data->td.td_deque == NULL);
3529 
3530   // Initialize last stolen task field to "none"
3531   thread_data->td.td_deque_last_stolen = -1;
3532 
3533   KMP_DEBUG_ASSERT(TCR_4(thread_data->td.td_deque_ntasks) == 0);
3534   KMP_DEBUG_ASSERT(thread_data->td.td_deque_head == 0);
3535   KMP_DEBUG_ASSERT(thread_data->td.td_deque_tail == 0);
3536 
3537   KE_TRACE(
3538       10,
3539       ("__kmp_alloc_task_deque: T#%d allocating deque[%d] for thread_data %p\n",
3540        __kmp_gtid_from_thread(thread), INITIAL_TASK_DEQUE_SIZE, thread_data));
3541   // Allocate space for task deque, and zero the deque
3542   // Cannot use __kmp_thread_calloc() because threads not around for
3543   // kmp_reap_task_team( ).
3544   thread_data->td.td_deque = (kmp_taskdata_t **)__kmp_allocate(
3545       INITIAL_TASK_DEQUE_SIZE * sizeof(kmp_taskdata_t *));
3546   thread_data->td.td_deque_size = INITIAL_TASK_DEQUE_SIZE;
3547 }
3548 
3549 // __kmp_free_task_deque:
3550 // Deallocates a task deque for a particular thread. Happens at library
3551 // deallocation so don't need to reset all thread data fields.
3552 static void __kmp_free_task_deque(kmp_thread_data_t *thread_data) {
3553   if (thread_data->td.td_deque != NULL) {
3554     __kmp_acquire_bootstrap_lock(&thread_data->td.td_deque_lock);
3555     TCW_4(thread_data->td.td_deque_ntasks, 0);
3556     __kmp_free(thread_data->td.td_deque);
3557     thread_data->td.td_deque = NULL;
3558     __kmp_release_bootstrap_lock(&thread_data->td.td_deque_lock);
3559   }
3560 
3561 #ifdef BUILD_TIED_TASK_STACK
3562   // GEH: Figure out what to do here for td_susp_tied_tasks
3563   if (thread_data->td.td_susp_tied_tasks.ts_entries != TASK_STACK_EMPTY) {
3564     __kmp_free_task_stack(__kmp_thread_from_gtid(gtid), thread_data);
3565   }
3566 #endif // BUILD_TIED_TASK_STACK
3567 }
3568 
3569 // __kmp_realloc_task_threads_data:
3570 // Allocates a threads_data array for a task team, either by allocating an
3571 // initial array or enlarging an existing array.  Only the first thread to get
3572 // the lock allocs or enlarges the array and re-initializes the array elements.
3573 // That thread returns "TRUE", the rest return "FALSE".
3574 // Assumes that the new array size is given by task_team -> tt.tt_nproc.
3575 // The current size is given by task_team -> tt.tt_max_threads.
3576 static int __kmp_realloc_task_threads_data(kmp_info_t *thread,
3577                                            kmp_task_team_t *task_team) {
3578   kmp_thread_data_t **threads_data_p;
3579   kmp_int32 nthreads, maxthreads;
3580   int is_init_thread = FALSE;
3581 
3582   if (TCR_4(task_team->tt.tt_found_tasks)) {
3583     // Already reallocated and initialized.
3584     return FALSE;
3585   }
3586 
3587   threads_data_p = &task_team->tt.tt_threads_data;
3588   nthreads = task_team->tt.tt_nproc;
3589   maxthreads = task_team->tt.tt_max_threads;
3590 
3591   // All threads must lock when they encounter the first task of the implicit
3592   // task region to make sure threads_data fields are (re)initialized before
3593   // used.
3594   __kmp_acquire_bootstrap_lock(&task_team->tt.tt_threads_lock);
3595 
3596   if (!TCR_4(task_team->tt.tt_found_tasks)) {
3597     // first thread to enable tasking
3598     kmp_team_t *team = thread->th.th_team;
3599     int i;
3600 
3601     is_init_thread = TRUE;
3602     if (maxthreads < nthreads) {
3603 
3604       if (*threads_data_p != NULL) {
3605         kmp_thread_data_t *old_data = *threads_data_p;
3606         kmp_thread_data_t *new_data = NULL;
3607 
3608         KE_TRACE(
3609             10,
3610             ("__kmp_realloc_task_threads_data: T#%d reallocating "
3611              "threads data for task_team %p, new_size = %d, old_size = %d\n",
3612              __kmp_gtid_from_thread(thread), task_team, nthreads, maxthreads));
3613         // Reallocate threads_data to have more elements than current array
3614         // Cannot use __kmp_thread_realloc() because threads not around for
3615         // kmp_reap_task_team( ).  Note all new array entries are initialized
3616         // to zero by __kmp_allocate().
3617         new_data = (kmp_thread_data_t *)__kmp_allocate(
3618             nthreads * sizeof(kmp_thread_data_t));
3619         // copy old data to new data
3620         KMP_MEMCPY_S((void *)new_data, nthreads * sizeof(kmp_thread_data_t),
3621                      (void *)old_data, maxthreads * sizeof(kmp_thread_data_t));
3622 
3623 #ifdef BUILD_TIED_TASK_STACK
3624         // GEH: Figure out if this is the right thing to do
3625         for (i = maxthreads; i < nthreads; i++) {
3626           kmp_thread_data_t *thread_data = &(*threads_data_p)[i];
3627           __kmp_init_task_stack(__kmp_gtid_from_thread(thread), thread_data);
3628         }
3629 #endif // BUILD_TIED_TASK_STACK
3630        // Install the new data and free the old data
3631         (*threads_data_p) = new_data;
3632         __kmp_free(old_data);
3633       } else {
3634         KE_TRACE(10, ("__kmp_realloc_task_threads_data: T#%d allocating "
3635                       "threads data for task_team %p, size = %d\n",
3636                       __kmp_gtid_from_thread(thread), task_team, nthreads));
3637         // Make the initial allocate for threads_data array, and zero entries
3638         // Cannot use __kmp_thread_calloc() because threads not around for
3639         // kmp_reap_task_team( ).
3640         *threads_data_p = (kmp_thread_data_t *)__kmp_allocate(
3641             nthreads * sizeof(kmp_thread_data_t));
3642 #ifdef BUILD_TIED_TASK_STACK
3643         // GEH: Figure out if this is the right thing to do
3644         for (i = 0; i < nthreads; i++) {
3645           kmp_thread_data_t *thread_data = &(*threads_data_p)[i];
3646           __kmp_init_task_stack(__kmp_gtid_from_thread(thread), thread_data);
3647         }
3648 #endif // BUILD_TIED_TASK_STACK
3649       }
3650       task_team->tt.tt_max_threads = nthreads;
3651     } else {
3652       // If array has (more than) enough elements, go ahead and use it
3653       KMP_DEBUG_ASSERT(*threads_data_p != NULL);
3654     }
3655 
3656     // initialize threads_data pointers back to thread_info structures
3657     for (i = 0; i < nthreads; i++) {
3658       kmp_thread_data_t *thread_data = &(*threads_data_p)[i];
3659       thread_data->td.td_thr = team->t.t_threads[i];
3660 
3661       if (thread_data->td.td_deque_last_stolen >= nthreads) {
3662         // The last stolen field survives across teams / barrier, and the number
3663         // of threads may have changed.  It's possible (likely?) that a new
3664         // parallel region will exhibit the same behavior as previous region.
3665         thread_data->td.td_deque_last_stolen = -1;
3666       }
3667     }
3668 
3669     KMP_MB();
3670     TCW_SYNC_4(task_team->tt.tt_found_tasks, TRUE);
3671   }
3672 
3673   __kmp_release_bootstrap_lock(&task_team->tt.tt_threads_lock);
3674   return is_init_thread;
3675 }
3676 
3677 // __kmp_free_task_threads_data:
3678 // Deallocates a threads_data array for a task team, including any attached
3679 // tasking deques.  Only occurs at library shutdown.
3680 static void __kmp_free_task_threads_data(kmp_task_team_t *task_team) {
3681   __kmp_acquire_bootstrap_lock(&task_team->tt.tt_threads_lock);
3682   if (task_team->tt.tt_threads_data != NULL) {
3683     int i;
3684     for (i = 0; i < task_team->tt.tt_max_threads; i++) {
3685       __kmp_free_task_deque(&task_team->tt.tt_threads_data[i]);
3686     }
3687     __kmp_free(task_team->tt.tt_threads_data);
3688     task_team->tt.tt_threads_data = NULL;
3689   }
3690   __kmp_release_bootstrap_lock(&task_team->tt.tt_threads_lock);
3691 }
3692 
3693 // __kmp_free_task_pri_list:
3694 // Deallocates tasking deques used for priority tasks.
3695 // Only occurs at library shutdown.
3696 static void __kmp_free_task_pri_list(kmp_task_team_t *task_team) {
3697   __kmp_acquire_bootstrap_lock(&task_team->tt.tt_task_pri_lock);
3698   if (task_team->tt.tt_task_pri_list != NULL) {
3699     kmp_task_pri_t *list = task_team->tt.tt_task_pri_list;
3700     while (list != NULL) {
3701       kmp_task_pri_t *next = list->next;
3702       __kmp_free_task_deque(&list->td);
3703       __kmp_free(list);
3704       list = next;
3705     }
3706     task_team->tt.tt_task_pri_list = NULL;
3707   }
3708   __kmp_release_bootstrap_lock(&task_team->tt.tt_task_pri_lock);
3709 }
3710 
3711 // __kmp_allocate_task_team:
3712 // Allocates a task team associated with a specific team, taking it from
3713 // the global task team free list if possible.  Also initializes data
3714 // structures.
3715 static kmp_task_team_t *__kmp_allocate_task_team(kmp_info_t *thread,
3716                                                  kmp_team_t *team) {
3717   kmp_task_team_t *task_team = NULL;
3718   int nthreads;
3719 
3720   KA_TRACE(20, ("__kmp_allocate_task_team: T#%d entering; team = %p\n",
3721                 (thread ? __kmp_gtid_from_thread(thread) : -1), team));
3722 
3723   if (TCR_PTR(__kmp_free_task_teams) != NULL) {
3724     // Take a task team from the task team pool
3725     __kmp_acquire_bootstrap_lock(&__kmp_task_team_lock);
3726     if (__kmp_free_task_teams != NULL) {
3727       task_team = __kmp_free_task_teams;
3728       TCW_PTR(__kmp_free_task_teams, task_team->tt.tt_next);
3729       task_team->tt.tt_next = NULL;
3730     }
3731     __kmp_release_bootstrap_lock(&__kmp_task_team_lock);
3732   }
3733 
3734   if (task_team == NULL) {
3735     KE_TRACE(10, ("__kmp_allocate_task_team: T#%d allocating "
3736                   "task team for team %p\n",
3737                   __kmp_gtid_from_thread(thread), team));
3738     // Allocate a new task team if one is not available. Cannot use
3739     // __kmp_thread_malloc because threads not around for kmp_reap_task_team.
3740     task_team = (kmp_task_team_t *)__kmp_allocate(sizeof(kmp_task_team_t));
3741     __kmp_init_bootstrap_lock(&task_team->tt.tt_threads_lock);
3742     __kmp_init_bootstrap_lock(&task_team->tt.tt_task_pri_lock);
3743 #if USE_ITT_BUILD && USE_ITT_NOTIFY && KMP_DEBUG
3744     // suppress race conditions detection on synchronization flags in debug mode
3745     // this helps to analyze library internals eliminating false positives
3746     __itt_suppress_mark_range(
3747         __itt_suppress_range, __itt_suppress_threading_errors,
3748         &task_team->tt.tt_found_tasks, sizeof(task_team->tt.tt_found_tasks));
3749     __itt_suppress_mark_range(__itt_suppress_range,
3750                               __itt_suppress_threading_errors,
3751                               CCAST(kmp_uint32 *, &task_team->tt.tt_active),
3752                               sizeof(task_team->tt.tt_active));
3753 #endif /* USE_ITT_BUILD && USE_ITT_NOTIFY && KMP_DEBUG */
3754     // Note: __kmp_allocate zeroes returned memory, othewise we would need:
3755     // task_team->tt.tt_threads_data = NULL;
3756     // task_team->tt.tt_max_threads = 0;
3757     // task_team->tt.tt_next = NULL;
3758   }
3759 
3760   TCW_4(task_team->tt.tt_found_tasks, FALSE);
3761   TCW_4(task_team->tt.tt_found_proxy_tasks, FALSE);
3762   TCW_4(task_team->tt.tt_hidden_helper_task_encountered, FALSE);
3763   task_team->tt.tt_nproc = nthreads = team->t.t_nproc;
3764 
3765   KMP_ATOMIC_ST_REL(&task_team->tt.tt_unfinished_threads, nthreads);
3766   TCW_4(task_team->tt.tt_hidden_helper_task_encountered, FALSE);
3767   TCW_4(task_team->tt.tt_active, TRUE);
3768 
3769   KA_TRACE(20, ("__kmp_allocate_task_team: T#%d exiting; task_team = %p "
3770                 "unfinished_threads init'd to %d\n",
3771                 (thread ? __kmp_gtid_from_thread(thread) : -1), task_team,
3772                 KMP_ATOMIC_LD_RLX(&task_team->tt.tt_unfinished_threads)));
3773   return task_team;
3774 }
3775 
3776 // __kmp_free_task_team:
3777 // Frees the task team associated with a specific thread, and adds it
3778 // to the global task team free list.
3779 void __kmp_free_task_team(kmp_info_t *thread, kmp_task_team_t *task_team) {
3780   KA_TRACE(20, ("__kmp_free_task_team: T#%d task_team = %p\n",
3781                 thread ? __kmp_gtid_from_thread(thread) : -1, task_team));
3782 
3783   // Put task team back on free list
3784   __kmp_acquire_bootstrap_lock(&__kmp_task_team_lock);
3785 
3786   KMP_DEBUG_ASSERT(task_team->tt.tt_next == NULL);
3787   task_team->tt.tt_next = __kmp_free_task_teams;
3788   TCW_PTR(__kmp_free_task_teams, task_team);
3789 
3790   __kmp_release_bootstrap_lock(&__kmp_task_team_lock);
3791 }
3792 
3793 // __kmp_reap_task_teams:
3794 // Free all the task teams on the task team free list.
3795 // Should only be done during library shutdown.
3796 // Cannot do anything that needs a thread structure or gtid since they are
3797 // already gone.
3798 void __kmp_reap_task_teams(void) {
3799   kmp_task_team_t *task_team;
3800 
3801   if (TCR_PTR(__kmp_free_task_teams) != NULL) {
3802     // Free all task_teams on the free list
3803     __kmp_acquire_bootstrap_lock(&__kmp_task_team_lock);
3804     while ((task_team = __kmp_free_task_teams) != NULL) {
3805       __kmp_free_task_teams = task_team->tt.tt_next;
3806       task_team->tt.tt_next = NULL;
3807 
3808       // Free threads_data if necessary
3809       if (task_team->tt.tt_threads_data != NULL) {
3810         __kmp_free_task_threads_data(task_team);
3811       }
3812       if (task_team->tt.tt_task_pri_list != NULL) {
3813         __kmp_free_task_pri_list(task_team);
3814       }
3815       __kmp_free(task_team);
3816     }
3817     __kmp_release_bootstrap_lock(&__kmp_task_team_lock);
3818   }
3819 }
3820 
3821 // __kmp_wait_to_unref_task_teams:
3822 // Some threads could still be in the fork barrier release code, possibly
3823 // trying to steal tasks.  Wait for each thread to unreference its task team.
3824 void __kmp_wait_to_unref_task_teams(void) {
3825   kmp_info_t *thread;
3826   kmp_uint32 spins;
3827   kmp_uint64 time;
3828   int done;
3829 
3830   KMP_INIT_YIELD(spins);
3831   KMP_INIT_BACKOFF(time);
3832 
3833   for (;;) {
3834     done = TRUE;
3835 
3836     // TODO: GEH - this may be is wrong because some sync would be necessary
3837     // in case threads are added to the pool during the traversal. Need to
3838     // verify that lock for thread pool is held when calling this routine.
3839     for (thread = CCAST(kmp_info_t *, __kmp_thread_pool); thread != NULL;
3840          thread = thread->th.th_next_pool) {
3841 #if KMP_OS_WINDOWS
3842       DWORD exit_val;
3843 #endif
3844       if (TCR_PTR(thread->th.th_task_team) == NULL) {
3845         KA_TRACE(10, ("__kmp_wait_to_unref_task_team: T#%d task_team == NULL\n",
3846                       __kmp_gtid_from_thread(thread)));
3847         continue;
3848       }
3849 #if KMP_OS_WINDOWS
3850       // TODO: GEH - add this check for Linux* OS / OS X* as well?
3851       if (!__kmp_is_thread_alive(thread, &exit_val)) {
3852         thread->th.th_task_team = NULL;
3853         continue;
3854       }
3855 #endif
3856 
3857       done = FALSE; // Because th_task_team pointer is not NULL for this thread
3858 
3859       KA_TRACE(10, ("__kmp_wait_to_unref_task_team: Waiting for T#%d to "
3860                     "unreference task_team\n",
3861                     __kmp_gtid_from_thread(thread)));
3862 
3863       if (__kmp_dflt_blocktime != KMP_MAX_BLOCKTIME) {
3864         void *sleep_loc;
3865         // If the thread is sleeping, awaken it.
3866         if ((sleep_loc = TCR_PTR(CCAST(void *, thread->th.th_sleep_loc))) !=
3867             NULL) {
3868           KA_TRACE(
3869               10,
3870               ("__kmp_wait_to_unref_task_team: T#%d waking up thread T#%d\n",
3871                __kmp_gtid_from_thread(thread), __kmp_gtid_from_thread(thread)));
3872           __kmp_null_resume_wrapper(thread);
3873         }
3874       }
3875     }
3876     if (done) {
3877       break;
3878     }
3879 
3880     // If oversubscribed or have waited a bit, yield.
3881     KMP_YIELD_OVERSUB_ELSE_SPIN(spins, time);
3882   }
3883 }
3884 
3885 // __kmp_task_team_setup:  Create a task_team for the current team, but use
3886 // an already created, unused one if it already exists.
3887 void __kmp_task_team_setup(kmp_info_t *this_thr, kmp_team_t *team, int always) {
3888   KMP_DEBUG_ASSERT(__kmp_tasking_mode != tskm_immediate_exec);
3889 
3890   // If this task_team hasn't been created yet, allocate it. It will be used in
3891   // the region after the next.
3892   // If it exists, it is the current task team and shouldn't be touched yet as
3893   // it may still be in use.
3894   if (team->t.t_task_team[this_thr->th.th_task_state] == NULL &&
3895       (always || team->t.t_nproc > 1)) {
3896     team->t.t_task_team[this_thr->th.th_task_state] =
3897         __kmp_allocate_task_team(this_thr, team);
3898     KA_TRACE(20, ("__kmp_task_team_setup: Primary T#%d created new task_team %p"
3899                   " for team %d at parity=%d\n",
3900                   __kmp_gtid_from_thread(this_thr),
3901                   team->t.t_task_team[this_thr->th.th_task_state], team->t.t_id,
3902                   this_thr->th.th_task_state));
3903   }
3904 
3905   // After threads exit the release, they will call sync, and then point to this
3906   // other task_team; make sure it is allocated and properly initialized. As
3907   // threads spin in the barrier release phase, they will continue to use the
3908   // previous task_team struct(above), until they receive the signal to stop
3909   // checking for tasks (they can't safely reference the kmp_team_t struct,
3910   // which could be reallocated by the primary thread). No task teams are formed
3911   // for serialized teams.
3912   if (team->t.t_nproc > 1) {
3913     int other_team = 1 - this_thr->th.th_task_state;
3914     KMP_DEBUG_ASSERT(other_team >= 0 && other_team < 2);
3915     if (team->t.t_task_team[other_team] == NULL) { // setup other team as well
3916       team->t.t_task_team[other_team] =
3917           __kmp_allocate_task_team(this_thr, team);
3918       KA_TRACE(20, ("__kmp_task_team_setup: Primary T#%d created second new "
3919                     "task_team %p for team %d at parity=%d\n",
3920                     __kmp_gtid_from_thread(this_thr),
3921                     team->t.t_task_team[other_team], team->t.t_id, other_team));
3922     } else { // Leave the old task team struct in place for the upcoming region;
3923       // adjust as needed
3924       kmp_task_team_t *task_team = team->t.t_task_team[other_team];
3925       if (!task_team->tt.tt_active ||
3926           team->t.t_nproc != task_team->tt.tt_nproc) {
3927         TCW_4(task_team->tt.tt_nproc, team->t.t_nproc);
3928         TCW_4(task_team->tt.tt_found_tasks, FALSE);
3929         TCW_4(task_team->tt.tt_found_proxy_tasks, FALSE);
3930         TCW_4(task_team->tt.tt_hidden_helper_task_encountered, FALSE);
3931         KMP_ATOMIC_ST_REL(&task_team->tt.tt_unfinished_threads,
3932                           team->t.t_nproc);
3933         TCW_4(task_team->tt.tt_active, TRUE);
3934       }
3935       // if team size has changed, the first thread to enable tasking will
3936       // realloc threads_data if necessary
3937       KA_TRACE(20, ("__kmp_task_team_setup: Primary T#%d reset next task_team "
3938                     "%p for team %d at parity=%d\n",
3939                     __kmp_gtid_from_thread(this_thr),
3940                     team->t.t_task_team[other_team], team->t.t_id, other_team));
3941     }
3942   }
3943 
3944   // For regular thread, task enabling should be called when the task is going
3945   // to be pushed to a dequeue. However, for the hidden helper thread, we need
3946   // it ahead of time so that some operations can be performed without race
3947   // condition.
3948   if (this_thr == __kmp_hidden_helper_main_thread) {
3949     for (int i = 0; i < 2; ++i) {
3950       kmp_task_team_t *task_team = team->t.t_task_team[i];
3951       if (KMP_TASKING_ENABLED(task_team)) {
3952         continue;
3953       }
3954       __kmp_enable_tasking(task_team, this_thr);
3955       for (int j = 0; j < task_team->tt.tt_nproc; ++j) {
3956         kmp_thread_data_t *thread_data = &task_team->tt.tt_threads_data[j];
3957         if (thread_data->td.td_deque == NULL) {
3958           __kmp_alloc_task_deque(__kmp_hidden_helper_threads[j], thread_data);
3959         }
3960       }
3961     }
3962   }
3963 }
3964 
3965 // __kmp_task_team_sync: Propagation of task team data from team to threads
3966 // which happens just after the release phase of a team barrier.  This may be
3967 // called by any thread, but only for teams with # threads > 1.
3968 void __kmp_task_team_sync(kmp_info_t *this_thr, kmp_team_t *team) {
3969   KMP_DEBUG_ASSERT(__kmp_tasking_mode != tskm_immediate_exec);
3970 
3971   // Toggle the th_task_state field, to switch which task_team this thread
3972   // refers to
3973   this_thr->th.th_task_state = (kmp_uint8)(1 - this_thr->th.th_task_state);
3974 
3975   // It is now safe to propagate the task team pointer from the team struct to
3976   // the current thread.
3977   TCW_PTR(this_thr->th.th_task_team,
3978           team->t.t_task_team[this_thr->th.th_task_state]);
3979   KA_TRACE(20,
3980            ("__kmp_task_team_sync: Thread T#%d task team switched to task_team "
3981             "%p from Team #%d (parity=%d)\n",
3982             __kmp_gtid_from_thread(this_thr), this_thr->th.th_task_team,
3983             team->t.t_id, this_thr->th.th_task_state));
3984 }
3985 
3986 // __kmp_task_team_wait: Primary thread waits for outstanding tasks after the
3987 // barrier gather phase. Only called by primary thread if #threads in team > 1
3988 // or if proxy tasks were created.
3989 //
3990 // wait is a flag that defaults to 1 (see kmp.h), but waiting can be turned off
3991 // by passing in 0 optionally as the last argument. When wait is zero, primary
3992 // thread does not wait for unfinished_threads to reach 0.
3993 void __kmp_task_team_wait(
3994     kmp_info_t *this_thr,
3995     kmp_team_t *team USE_ITT_BUILD_ARG(void *itt_sync_obj), int wait) {
3996   kmp_task_team_t *task_team = team->t.t_task_team[this_thr->th.th_task_state];
3997 
3998   KMP_DEBUG_ASSERT(__kmp_tasking_mode != tskm_immediate_exec);
3999   KMP_DEBUG_ASSERT(task_team == this_thr->th.th_task_team);
4000 
4001   if ((task_team != NULL) && KMP_TASKING_ENABLED(task_team)) {
4002     if (wait) {
4003       KA_TRACE(20, ("__kmp_task_team_wait: Primary T#%d waiting for all tasks "
4004                     "(for unfinished_threads to reach 0) on task_team = %p\n",
4005                     __kmp_gtid_from_thread(this_thr), task_team));
4006       // Worker threads may have dropped through to release phase, but could
4007       // still be executing tasks. Wait here for tasks to complete. To avoid
4008       // memory contention, only primary thread checks termination condition.
4009       kmp_flag_32<false, false> flag(
4010           RCAST(std::atomic<kmp_uint32> *,
4011                 &task_team->tt.tt_unfinished_threads),
4012           0U);
4013       flag.wait(this_thr, TRUE USE_ITT_BUILD_ARG(itt_sync_obj));
4014     }
4015     // Deactivate the old task team, so that the worker threads will stop
4016     // referencing it while spinning.
4017     KA_TRACE(
4018         20,
4019         ("__kmp_task_team_wait: Primary T#%d deactivating task_team %p: "
4020          "setting active to false, setting local and team's pointer to NULL\n",
4021          __kmp_gtid_from_thread(this_thr), task_team));
4022     KMP_DEBUG_ASSERT(task_team->tt.tt_nproc > 1 ||
4023                      task_team->tt.tt_found_proxy_tasks == TRUE ||
4024                      task_team->tt.tt_hidden_helper_task_encountered == TRUE);
4025     TCW_SYNC_4(task_team->tt.tt_found_proxy_tasks, FALSE);
4026     TCW_SYNC_4(task_team->tt.tt_hidden_helper_task_encountered, FALSE);
4027     KMP_CHECK_UPDATE(task_team->tt.tt_untied_task_encountered, 0);
4028     TCW_SYNC_4(task_team->tt.tt_active, FALSE);
4029     KMP_MB();
4030 
4031     TCW_PTR(this_thr->th.th_task_team, NULL);
4032   }
4033 }
4034 
4035 // __kmp_tasking_barrier:
4036 // This routine is called only when __kmp_tasking_mode == tskm_extra_barrier.
4037 // Internal function to execute all tasks prior to a regular barrier or a join
4038 // barrier. It is a full barrier itself, which unfortunately turns regular
4039 // barriers into double barriers and join barriers into 1 1/2 barriers.
4040 void __kmp_tasking_barrier(kmp_team_t *team, kmp_info_t *thread, int gtid) {
4041   std::atomic<kmp_uint32> *spin = RCAST(
4042       std::atomic<kmp_uint32> *,
4043       &team->t.t_task_team[thread->th.th_task_state]->tt.tt_unfinished_threads);
4044   int flag = FALSE;
4045   KMP_DEBUG_ASSERT(__kmp_tasking_mode == tskm_extra_barrier);
4046 
4047 #if USE_ITT_BUILD
4048   KMP_FSYNC_SPIN_INIT(spin, NULL);
4049 #endif /* USE_ITT_BUILD */
4050   kmp_flag_32<false, false> spin_flag(spin, 0U);
4051   while (!spin_flag.execute_tasks(thread, gtid, TRUE,
4052                                   &flag USE_ITT_BUILD_ARG(NULL), 0)) {
4053 #if USE_ITT_BUILD
4054     // TODO: What about itt_sync_obj??
4055     KMP_FSYNC_SPIN_PREPARE(RCAST(void *, spin));
4056 #endif /* USE_ITT_BUILD */
4057 
4058     if (TCR_4(__kmp_global.g.g_done)) {
4059       if (__kmp_global.g.g_abort)
4060         __kmp_abort_thread();
4061       break;
4062     }
4063     KMP_YIELD(TRUE);
4064   }
4065 #if USE_ITT_BUILD
4066   KMP_FSYNC_SPIN_ACQUIRED(RCAST(void *, spin));
4067 #endif /* USE_ITT_BUILD */
4068 }
4069 
4070 // __kmp_give_task puts a task into a given thread queue if:
4071 //  - the queue for that thread was created
4072 //  - there's space in that queue
4073 // Because of this, __kmp_push_task needs to check if there's space after
4074 // getting the lock
4075 static bool __kmp_give_task(kmp_info_t *thread, kmp_int32 tid, kmp_task_t *task,
4076                             kmp_int32 pass) {
4077   kmp_taskdata_t *taskdata = KMP_TASK_TO_TASKDATA(task);
4078   kmp_task_team_t *task_team = taskdata->td_task_team;
4079 
4080   KA_TRACE(20, ("__kmp_give_task: trying to give task %p to thread %d.\n",
4081                 taskdata, tid));
4082 
4083   // If task_team is NULL something went really bad...
4084   KMP_DEBUG_ASSERT(task_team != NULL);
4085 
4086   bool result = false;
4087   kmp_thread_data_t *thread_data = &task_team->tt.tt_threads_data[tid];
4088 
4089   if (thread_data->td.td_deque == NULL) {
4090     // There's no queue in this thread, go find another one
4091     // We're guaranteed that at least one thread has a queue
4092     KA_TRACE(30,
4093              ("__kmp_give_task: thread %d has no queue while giving task %p.\n",
4094               tid, taskdata));
4095     return result;
4096   }
4097 
4098   if (TCR_4(thread_data->td.td_deque_ntasks) >=
4099       TASK_DEQUE_SIZE(thread_data->td)) {
4100     KA_TRACE(
4101         30,
4102         ("__kmp_give_task: queue is full while giving task %p to thread %d.\n",
4103          taskdata, tid));
4104 
4105     // if this deque is bigger than the pass ratio give a chance to another
4106     // thread
4107     if (TASK_DEQUE_SIZE(thread_data->td) / INITIAL_TASK_DEQUE_SIZE >= pass)
4108       return result;
4109 
4110     __kmp_acquire_bootstrap_lock(&thread_data->td.td_deque_lock);
4111     if (TCR_4(thread_data->td.td_deque_ntasks) >=
4112         TASK_DEQUE_SIZE(thread_data->td)) {
4113       // expand deque to push the task which is not allowed to execute
4114       __kmp_realloc_task_deque(thread, thread_data);
4115     }
4116 
4117   } else {
4118 
4119     __kmp_acquire_bootstrap_lock(&thread_data->td.td_deque_lock);
4120 
4121     if (TCR_4(thread_data->td.td_deque_ntasks) >=
4122         TASK_DEQUE_SIZE(thread_data->td)) {
4123       KA_TRACE(30, ("__kmp_give_task: queue is full while giving task %p to "
4124                     "thread %d.\n",
4125                     taskdata, tid));
4126 
4127       // if this deque is bigger than the pass ratio give a chance to another
4128       // thread
4129       if (TASK_DEQUE_SIZE(thread_data->td) / INITIAL_TASK_DEQUE_SIZE >= pass)
4130         goto release_and_exit;
4131 
4132       __kmp_realloc_task_deque(thread, thread_data);
4133     }
4134   }
4135 
4136   // lock is held here, and there is space in the deque
4137 
4138   thread_data->td.td_deque[thread_data->td.td_deque_tail] = taskdata;
4139   // Wrap index.
4140   thread_data->td.td_deque_tail =
4141       (thread_data->td.td_deque_tail + 1) & TASK_DEQUE_MASK(thread_data->td);
4142   TCW_4(thread_data->td.td_deque_ntasks,
4143         TCR_4(thread_data->td.td_deque_ntasks) + 1);
4144 
4145   result = true;
4146   KA_TRACE(30, ("__kmp_give_task: successfully gave task %p to thread %d.\n",
4147                 taskdata, tid));
4148 
4149 release_and_exit:
4150   __kmp_release_bootstrap_lock(&thread_data->td.td_deque_lock);
4151 
4152   return result;
4153 }
4154 
4155 #define PROXY_TASK_FLAG 0x40000000
4156 /* The finish of the proxy tasks is divided in two pieces:
4157     - the top half is the one that can be done from a thread outside the team
4158     - the bottom half must be run from a thread within the team
4159 
4160    In order to run the bottom half the task gets queued back into one of the
4161    threads of the team. Once the td_incomplete_child_task counter of the parent
4162    is decremented the threads can leave the barriers. So, the bottom half needs
4163    to be queued before the counter is decremented. The top half is therefore
4164    divided in two parts:
4165     - things that can be run before queuing the bottom half
4166     - things that must be run after queuing the bottom half
4167 
4168    This creates a second race as the bottom half can free the task before the
4169    second top half is executed. To avoid this we use the
4170    td_incomplete_child_task of the proxy task to synchronize the top and bottom
4171    half. */
4172 static void __kmp_first_top_half_finish_proxy(kmp_taskdata_t *taskdata) {
4173   KMP_DEBUG_ASSERT(taskdata->td_flags.tasktype == TASK_EXPLICIT);
4174   KMP_DEBUG_ASSERT(taskdata->td_flags.proxy == TASK_PROXY);
4175   KMP_DEBUG_ASSERT(taskdata->td_flags.complete == 0);
4176   KMP_DEBUG_ASSERT(taskdata->td_flags.freed == 0);
4177 
4178   taskdata->td_flags.complete = 1; // mark the task as completed
4179 
4180   if (taskdata->td_taskgroup)
4181     KMP_ATOMIC_DEC(&taskdata->td_taskgroup->count);
4182 
4183   // Create an imaginary children for this task so the bottom half cannot
4184   // release the task before we have completed the second top half
4185   KMP_ATOMIC_OR(&taskdata->td_incomplete_child_tasks, PROXY_TASK_FLAG);
4186 }
4187 
4188 static void __kmp_second_top_half_finish_proxy(kmp_taskdata_t *taskdata) {
4189 #if KMP_DEBUG
4190   kmp_int32 children = 0;
4191   // Predecrement simulated by "- 1" calculation
4192   children = -1 +
4193 #endif
4194       KMP_ATOMIC_DEC(&taskdata->td_parent->td_incomplete_child_tasks);
4195   KMP_DEBUG_ASSERT(children >= 0);
4196 
4197   // Remove the imaginary children
4198   KMP_ATOMIC_AND(&taskdata->td_incomplete_child_tasks, ~PROXY_TASK_FLAG);
4199 }
4200 
4201 static void __kmp_bottom_half_finish_proxy(kmp_int32 gtid, kmp_task_t *ptask) {
4202   kmp_taskdata_t *taskdata = KMP_TASK_TO_TASKDATA(ptask);
4203   kmp_info_t *thread = __kmp_threads[gtid];
4204 
4205   KMP_DEBUG_ASSERT(taskdata->td_flags.proxy == TASK_PROXY);
4206   KMP_DEBUG_ASSERT(taskdata->td_flags.complete ==
4207                    1); // top half must run before bottom half
4208 
4209   // We need to wait to make sure the top half is finished
4210   // Spinning here should be ok as this should happen quickly
4211   while ((KMP_ATOMIC_LD_ACQ(&taskdata->td_incomplete_child_tasks) &
4212           PROXY_TASK_FLAG) > 0)
4213     ;
4214 
4215   __kmp_release_deps(gtid, taskdata);
4216   __kmp_free_task_and_ancestors(gtid, taskdata, thread);
4217 }
4218 
4219 /*!
4220 @ingroup TASKING
4221 @param gtid Global Thread ID of encountering thread
4222 @param ptask Task which execution is completed
4223 
4224 Execute the completion of a proxy task from a thread of that is part of the
4225 team. Run first and bottom halves directly.
4226 */
4227 void __kmpc_proxy_task_completed(kmp_int32 gtid, kmp_task_t *ptask) {
4228   KMP_DEBUG_ASSERT(ptask != NULL);
4229   kmp_taskdata_t *taskdata = KMP_TASK_TO_TASKDATA(ptask);
4230   KA_TRACE(
4231       10, ("__kmp_proxy_task_completed(enter): T#%d proxy task %p completing\n",
4232            gtid, taskdata));
4233   __kmp_assert_valid_gtid(gtid);
4234   KMP_DEBUG_ASSERT(taskdata->td_flags.proxy == TASK_PROXY);
4235 
4236   __kmp_first_top_half_finish_proxy(taskdata);
4237   __kmp_second_top_half_finish_proxy(taskdata);
4238   __kmp_bottom_half_finish_proxy(gtid, ptask);
4239 
4240   KA_TRACE(10,
4241            ("__kmp_proxy_task_completed(exit): T#%d proxy task %p completing\n",
4242             gtid, taskdata));
4243 }
4244 
4245 void __kmpc_give_task(kmp_task_t *ptask, kmp_int32 start = 0) {
4246   KMP_DEBUG_ASSERT(ptask != NULL);
4247   kmp_taskdata_t *taskdata = KMP_TASK_TO_TASKDATA(ptask);
4248 
4249   // Enqueue task to complete bottom half completion from a thread within the
4250   // corresponding team
4251   kmp_team_t *team = taskdata->td_team;
4252   kmp_int32 nthreads = team->t.t_nproc;
4253   kmp_info_t *thread;
4254 
4255   // This should be similar to start_k = __kmp_get_random( thread ) % nthreads
4256   // but we cannot use __kmp_get_random here
4257   kmp_int32 start_k = start % nthreads;
4258   kmp_int32 pass = 1;
4259   kmp_int32 k = start_k;
4260 
4261   do {
4262     // For now we're just linearly trying to find a thread
4263     thread = team->t.t_threads[k];
4264     k = (k + 1) % nthreads;
4265 
4266     // we did a full pass through all the threads
4267     if (k == start_k)
4268       pass = pass << 1;
4269 
4270   } while (!__kmp_give_task(thread, k, ptask, pass));
4271 }
4272 
4273 /*!
4274 @ingroup TASKING
4275 @param ptask Task which execution is completed
4276 
4277 Execute the completion of a proxy task from a thread that could not belong to
4278 the team.
4279 */
4280 void __kmpc_proxy_task_completed_ooo(kmp_task_t *ptask) {
4281   KMP_DEBUG_ASSERT(ptask != NULL);
4282   kmp_taskdata_t *taskdata = KMP_TASK_TO_TASKDATA(ptask);
4283 
4284   KA_TRACE(
4285       10,
4286       ("__kmp_proxy_task_completed_ooo(enter): proxy task completing ooo %p\n",
4287        taskdata));
4288 
4289   KMP_DEBUG_ASSERT(taskdata->td_flags.proxy == TASK_PROXY);
4290 
4291   __kmp_first_top_half_finish_proxy(taskdata);
4292 
4293   __kmpc_give_task(ptask);
4294 
4295   __kmp_second_top_half_finish_proxy(taskdata);
4296 
4297   KA_TRACE(
4298       10,
4299       ("__kmp_proxy_task_completed_ooo(exit): proxy task completing ooo %p\n",
4300        taskdata));
4301 }
4302 
4303 kmp_event_t *__kmpc_task_allow_completion_event(ident_t *loc_ref, int gtid,
4304                                                 kmp_task_t *task) {
4305   kmp_taskdata_t *td = KMP_TASK_TO_TASKDATA(task);
4306   if (td->td_allow_completion_event.type == KMP_EVENT_UNINITIALIZED) {
4307     td->td_allow_completion_event.type = KMP_EVENT_ALLOW_COMPLETION;
4308     td->td_allow_completion_event.ed.task = task;
4309     __kmp_init_tas_lock(&td->td_allow_completion_event.lock);
4310   }
4311   return &td->td_allow_completion_event;
4312 }
4313 
4314 void __kmp_fulfill_event(kmp_event_t *event) {
4315   if (event->type == KMP_EVENT_ALLOW_COMPLETION) {
4316     kmp_task_t *ptask = event->ed.task;
4317     kmp_taskdata_t *taskdata = KMP_TASK_TO_TASKDATA(ptask);
4318     bool detached = false;
4319     int gtid = __kmp_get_gtid();
4320 
4321     // The associated task might have completed or could be completing at this
4322     // point.
4323     // We need to take the lock to avoid races
4324     __kmp_acquire_tas_lock(&event->lock, gtid);
4325     if (taskdata->td_flags.proxy == TASK_PROXY) {
4326       detached = true;
4327     } else {
4328 #if OMPT_SUPPORT
4329       // The OMPT event must occur under mutual exclusion,
4330       // otherwise the tool might access ptask after free
4331       if (UNLIKELY(ompt_enabled.enabled))
4332         __ompt_task_finish(ptask, NULL, ompt_task_early_fulfill);
4333 #endif
4334     }
4335     event->type = KMP_EVENT_UNINITIALIZED;
4336     __kmp_release_tas_lock(&event->lock, gtid);
4337 
4338     if (detached) {
4339 #if OMPT_SUPPORT
4340       // We free ptask afterwards and know the task is finished,
4341       // so locking is not necessary
4342       if (UNLIKELY(ompt_enabled.enabled))
4343         __ompt_task_finish(ptask, NULL, ompt_task_late_fulfill);
4344 #endif
4345       // If the task detached complete the proxy task
4346       if (gtid >= 0) {
4347         kmp_team_t *team = taskdata->td_team;
4348         kmp_info_t *thread = __kmp_get_thread();
4349         if (thread->th.th_team == team) {
4350           __kmpc_proxy_task_completed(gtid, ptask);
4351           return;
4352         }
4353       }
4354 
4355       // fallback
4356       __kmpc_proxy_task_completed_ooo(ptask);
4357     }
4358   }
4359 }
4360 
4361 // __kmp_task_dup_alloc: Allocate the taskdata and make a copy of source task
4362 // for taskloop
4363 //
4364 // thread:   allocating thread
4365 // task_src: pointer to source task to be duplicated
4366 // returns:  a pointer to the allocated kmp_task_t structure (task).
4367 kmp_task_t *__kmp_task_dup_alloc(kmp_info_t *thread, kmp_task_t *task_src) {
4368   kmp_task_t *task;
4369   kmp_taskdata_t *taskdata;
4370   kmp_taskdata_t *taskdata_src = KMP_TASK_TO_TASKDATA(task_src);
4371   kmp_taskdata_t *parent_task = taskdata_src->td_parent; // same parent task
4372   size_t shareds_offset;
4373   size_t task_size;
4374 
4375   KA_TRACE(10, ("__kmp_task_dup_alloc(enter): Th %p, source task %p\n", thread,
4376                 task_src));
4377   KMP_DEBUG_ASSERT(taskdata_src->td_flags.proxy ==
4378                    TASK_FULL); // it should not be proxy task
4379   KMP_DEBUG_ASSERT(taskdata_src->td_flags.tasktype == TASK_EXPLICIT);
4380   task_size = taskdata_src->td_size_alloc;
4381 
4382   // Allocate a kmp_taskdata_t block and a kmp_task_t block.
4383   KA_TRACE(30, ("__kmp_task_dup_alloc: Th %p, malloc size %ld\n", thread,
4384                 task_size));
4385 #if USE_FAST_MEMORY
4386   taskdata = (kmp_taskdata_t *)__kmp_fast_allocate(thread, task_size);
4387 #else
4388   taskdata = (kmp_taskdata_t *)__kmp_thread_malloc(thread, task_size);
4389 #endif /* USE_FAST_MEMORY */
4390   KMP_MEMCPY(taskdata, taskdata_src, task_size);
4391 
4392   task = KMP_TASKDATA_TO_TASK(taskdata);
4393 
4394   // Initialize new task (only specific fields not affected by memcpy)
4395   taskdata->td_task_id = KMP_GEN_TASK_ID();
4396   if (task->shareds != NULL) { // need setup shareds pointer
4397     shareds_offset = (char *)task_src->shareds - (char *)taskdata_src;
4398     task->shareds = &((char *)taskdata)[shareds_offset];
4399     KMP_DEBUG_ASSERT((((kmp_uintptr_t)task->shareds) & (sizeof(void *) - 1)) ==
4400                      0);
4401   }
4402   taskdata->td_alloc_thread = thread;
4403   taskdata->td_parent = parent_task;
4404   // task inherits the taskgroup from the parent task
4405   taskdata->td_taskgroup = parent_task->td_taskgroup;
4406   // tied task needs to initialize the td_last_tied at creation,
4407   // untied one does this when it is scheduled for execution
4408   if (taskdata->td_flags.tiedness == TASK_TIED)
4409     taskdata->td_last_tied = taskdata;
4410 
4411   // Only need to keep track of child task counts if team parallel and tasking
4412   // not serialized
4413   if (!(taskdata->td_flags.team_serial || taskdata->td_flags.tasking_ser)) {
4414     KMP_ATOMIC_INC(&parent_task->td_incomplete_child_tasks);
4415     if (parent_task->td_taskgroup)
4416       KMP_ATOMIC_INC(&parent_task->td_taskgroup->count);
4417     // Only need to keep track of allocated child tasks for explicit tasks since
4418     // implicit not deallocated
4419     if (taskdata->td_parent->td_flags.tasktype == TASK_EXPLICIT)
4420       KMP_ATOMIC_INC(&taskdata->td_parent->td_allocated_child_tasks);
4421   }
4422 
4423   KA_TRACE(20,
4424            ("__kmp_task_dup_alloc(exit): Th %p, created task %p, parent=%p\n",
4425             thread, taskdata, taskdata->td_parent));
4426 #if OMPT_SUPPORT
4427   if (UNLIKELY(ompt_enabled.enabled))
4428     __ompt_task_init(taskdata, thread->th.th_info.ds.ds_gtid);
4429 #endif
4430   return task;
4431 }
4432 
4433 // Routine optionally generated by the compiler for setting the lastprivate flag
4434 // and calling needed constructors for private/firstprivate objects
4435 // (used to form taskloop tasks from pattern task)
4436 // Parameters: dest task, src task, lastprivate flag.
4437 typedef void (*p_task_dup_t)(kmp_task_t *, kmp_task_t *, kmp_int32);
4438 
4439 KMP_BUILD_ASSERT(sizeof(long) == 4 || sizeof(long) == 8);
4440 
4441 // class to encapsulate manipulating loop bounds in a taskloop task.
4442 // this abstracts away the Intel vs GOMP taskloop interface for setting/getting
4443 // the loop bound variables.
4444 class kmp_taskloop_bounds_t {
4445   kmp_task_t *task;
4446   const kmp_taskdata_t *taskdata;
4447   size_t lower_offset;
4448   size_t upper_offset;
4449 
4450 public:
4451   kmp_taskloop_bounds_t(kmp_task_t *_task, kmp_uint64 *lb, kmp_uint64 *ub)
4452       : task(_task), taskdata(KMP_TASK_TO_TASKDATA(task)),
4453         lower_offset((char *)lb - (char *)task),
4454         upper_offset((char *)ub - (char *)task) {
4455     KMP_DEBUG_ASSERT((char *)lb > (char *)_task);
4456     KMP_DEBUG_ASSERT((char *)ub > (char *)_task);
4457   }
4458   kmp_taskloop_bounds_t(kmp_task_t *_task, const kmp_taskloop_bounds_t &bounds)
4459       : task(_task), taskdata(KMP_TASK_TO_TASKDATA(_task)),
4460         lower_offset(bounds.lower_offset), upper_offset(bounds.upper_offset) {}
4461   size_t get_lower_offset() const { return lower_offset; }
4462   size_t get_upper_offset() const { return upper_offset; }
4463   kmp_uint64 get_lb() const {
4464     kmp_int64 retval;
4465 #if defined(KMP_GOMP_COMPAT)
4466     // Intel task just returns the lower bound normally
4467     if (!taskdata->td_flags.native) {
4468       retval = *(kmp_int64 *)((char *)task + lower_offset);
4469     } else {
4470       // GOMP task has to take into account the sizeof(long)
4471       if (taskdata->td_size_loop_bounds == 4) {
4472         kmp_int32 *lb = RCAST(kmp_int32 *, task->shareds);
4473         retval = (kmp_int64)*lb;
4474       } else {
4475         kmp_int64 *lb = RCAST(kmp_int64 *, task->shareds);
4476         retval = (kmp_int64)*lb;
4477       }
4478     }
4479 #else
4480     (void)taskdata;
4481     retval = *(kmp_int64 *)((char *)task + lower_offset);
4482 #endif // defined(KMP_GOMP_COMPAT)
4483     return retval;
4484   }
4485   kmp_uint64 get_ub() const {
4486     kmp_int64 retval;
4487 #if defined(KMP_GOMP_COMPAT)
4488     // Intel task just returns the upper bound normally
4489     if (!taskdata->td_flags.native) {
4490       retval = *(kmp_int64 *)((char *)task + upper_offset);
4491     } else {
4492       // GOMP task has to take into account the sizeof(long)
4493       if (taskdata->td_size_loop_bounds == 4) {
4494         kmp_int32 *ub = RCAST(kmp_int32 *, task->shareds) + 1;
4495         retval = (kmp_int64)*ub;
4496       } else {
4497         kmp_int64 *ub = RCAST(kmp_int64 *, task->shareds) + 1;
4498         retval = (kmp_int64)*ub;
4499       }
4500     }
4501 #else
4502     retval = *(kmp_int64 *)((char *)task + upper_offset);
4503 #endif // defined(KMP_GOMP_COMPAT)
4504     return retval;
4505   }
4506   void set_lb(kmp_uint64 lb) {
4507 #if defined(KMP_GOMP_COMPAT)
4508     // Intel task just sets the lower bound normally
4509     if (!taskdata->td_flags.native) {
4510       *(kmp_uint64 *)((char *)task + lower_offset) = lb;
4511     } else {
4512       // GOMP task has to take into account the sizeof(long)
4513       if (taskdata->td_size_loop_bounds == 4) {
4514         kmp_uint32 *lower = RCAST(kmp_uint32 *, task->shareds);
4515         *lower = (kmp_uint32)lb;
4516       } else {
4517         kmp_uint64 *lower = RCAST(kmp_uint64 *, task->shareds);
4518         *lower = (kmp_uint64)lb;
4519       }
4520     }
4521 #else
4522     *(kmp_uint64 *)((char *)task + lower_offset) = lb;
4523 #endif // defined(KMP_GOMP_COMPAT)
4524   }
4525   void set_ub(kmp_uint64 ub) {
4526 #if defined(KMP_GOMP_COMPAT)
4527     // Intel task just sets the upper bound normally
4528     if (!taskdata->td_flags.native) {
4529       *(kmp_uint64 *)((char *)task + upper_offset) = ub;
4530     } else {
4531       // GOMP task has to take into account the sizeof(long)
4532       if (taskdata->td_size_loop_bounds == 4) {
4533         kmp_uint32 *upper = RCAST(kmp_uint32 *, task->shareds) + 1;
4534         *upper = (kmp_uint32)ub;
4535       } else {
4536         kmp_uint64 *upper = RCAST(kmp_uint64 *, task->shareds) + 1;
4537         *upper = (kmp_uint64)ub;
4538       }
4539     }
4540 #else
4541     *(kmp_uint64 *)((char *)task + upper_offset) = ub;
4542 #endif // defined(KMP_GOMP_COMPAT)
4543   }
4544 };
4545 
4546 // __kmp_taskloop_linear: Start tasks of the taskloop linearly
4547 //
4548 // loc        Source location information
4549 // gtid       Global thread ID
4550 // task       Pattern task, exposes the loop iteration range
4551 // lb         Pointer to loop lower bound in task structure
4552 // ub         Pointer to loop upper bound in task structure
4553 // st         Loop stride
4554 // ub_glob    Global upper bound (used for lastprivate check)
4555 // num_tasks  Number of tasks to execute
4556 // grainsize  Number of loop iterations per task
4557 // extras     Number of chunks with grainsize+1 iterations
4558 // last_chunk Reduction of grainsize for last task
4559 // tc         Iterations count
4560 // task_dup   Tasks duplication routine
4561 // codeptr_ra Return address for OMPT events
4562 void __kmp_taskloop_linear(ident_t *loc, int gtid, kmp_task_t *task,
4563                            kmp_uint64 *lb, kmp_uint64 *ub, kmp_int64 st,
4564                            kmp_uint64 ub_glob, kmp_uint64 num_tasks,
4565                            kmp_uint64 grainsize, kmp_uint64 extras,
4566                            kmp_int64 last_chunk, kmp_uint64 tc,
4567 #if OMPT_SUPPORT
4568                            void *codeptr_ra,
4569 #endif
4570                            void *task_dup) {
4571   KMP_COUNT_BLOCK(OMP_TASKLOOP);
4572   KMP_TIME_PARTITIONED_BLOCK(OMP_taskloop_scheduling);
4573   p_task_dup_t ptask_dup = (p_task_dup_t)task_dup;
4574   // compiler provides global bounds here
4575   kmp_taskloop_bounds_t task_bounds(task, lb, ub);
4576   kmp_uint64 lower = task_bounds.get_lb();
4577   kmp_uint64 upper = task_bounds.get_ub();
4578   kmp_uint64 i;
4579   kmp_info_t *thread = __kmp_threads[gtid];
4580   kmp_taskdata_t *current_task = thread->th.th_current_task;
4581   kmp_task_t *next_task;
4582   kmp_int32 lastpriv = 0;
4583 
4584   KMP_DEBUG_ASSERT(tc == num_tasks * grainsize +
4585                              (last_chunk < 0 ? last_chunk : extras));
4586   KMP_DEBUG_ASSERT(num_tasks > extras);
4587   KMP_DEBUG_ASSERT(num_tasks > 0);
4588   KA_TRACE(20, ("__kmp_taskloop_linear: T#%d: %lld tasks, grainsize %lld, "
4589                 "extras %lld, last_chunk %lld, i=%lld,%lld(%d)%lld, dup %p\n",
4590                 gtid, num_tasks, grainsize, extras, last_chunk, lower, upper,
4591                 ub_glob, st, task_dup));
4592 
4593   // Launch num_tasks tasks, assign grainsize iterations each task
4594   for (i = 0; i < num_tasks; ++i) {
4595     kmp_uint64 chunk_minus_1;
4596     if (extras == 0) {
4597       chunk_minus_1 = grainsize - 1;
4598     } else {
4599       chunk_minus_1 = grainsize;
4600       --extras; // first extras iterations get bigger chunk (grainsize+1)
4601     }
4602     upper = lower + st * chunk_minus_1;
4603     if (upper > *ub) {
4604       upper = *ub;
4605     }
4606     if (i == num_tasks - 1) {
4607       // schedule the last task, set lastprivate flag if needed
4608       if (st == 1) { // most common case
4609         KMP_DEBUG_ASSERT(upper == *ub);
4610         if (upper == ub_glob)
4611           lastpriv = 1;
4612       } else if (st > 0) { // positive loop stride
4613         KMP_DEBUG_ASSERT((kmp_uint64)st > *ub - upper);
4614         if ((kmp_uint64)st > ub_glob - upper)
4615           lastpriv = 1;
4616       } else { // negative loop stride
4617         KMP_DEBUG_ASSERT(upper + st < *ub);
4618         if (upper - ub_glob < (kmp_uint64)(-st))
4619           lastpriv = 1;
4620       }
4621     }
4622     next_task = __kmp_task_dup_alloc(thread, task); // allocate new task
4623     kmp_taskdata_t *next_taskdata = KMP_TASK_TO_TASKDATA(next_task);
4624     kmp_taskloop_bounds_t next_task_bounds =
4625         kmp_taskloop_bounds_t(next_task, task_bounds);
4626 
4627     // adjust task-specific bounds
4628     next_task_bounds.set_lb(lower);
4629     if (next_taskdata->td_flags.native) {
4630       next_task_bounds.set_ub(upper + (st > 0 ? 1 : -1));
4631     } else {
4632       next_task_bounds.set_ub(upper);
4633     }
4634     if (ptask_dup != NULL) // set lastprivate flag, construct firstprivates,
4635                            // etc.
4636       ptask_dup(next_task, task, lastpriv);
4637     KA_TRACE(40,
4638              ("__kmp_taskloop_linear: T#%d; task #%llu: task %p: lower %lld, "
4639               "upper %lld stride %lld, (offsets %p %p)\n",
4640               gtid, i, next_task, lower, upper, st,
4641               next_task_bounds.get_lower_offset(),
4642               next_task_bounds.get_upper_offset()));
4643 #if OMPT_SUPPORT
4644     __kmp_omp_taskloop_task(NULL, gtid, next_task,
4645                             codeptr_ra); // schedule new task
4646 #else
4647     __kmp_omp_task(gtid, next_task, true); // schedule new task
4648 #endif
4649     lower = upper + st; // adjust lower bound for the next iteration
4650   }
4651   // free the pattern task and exit
4652   __kmp_task_start(gtid, task, current_task); // make internal bookkeeping
4653   // do not execute the pattern task, just do internal bookkeeping
4654   __kmp_task_finish<false>(gtid, task, current_task);
4655 }
4656 
4657 // Structure to keep taskloop parameters for auxiliary task
4658 // kept in the shareds of the task structure.
4659 typedef struct __taskloop_params {
4660   kmp_task_t *task;
4661   kmp_uint64 *lb;
4662   kmp_uint64 *ub;
4663   void *task_dup;
4664   kmp_int64 st;
4665   kmp_uint64 ub_glob;
4666   kmp_uint64 num_tasks;
4667   kmp_uint64 grainsize;
4668   kmp_uint64 extras;
4669   kmp_int64 last_chunk;
4670   kmp_uint64 tc;
4671   kmp_uint64 num_t_min;
4672 #if OMPT_SUPPORT
4673   void *codeptr_ra;
4674 #endif
4675 } __taskloop_params_t;
4676 
4677 void __kmp_taskloop_recur(ident_t *, int, kmp_task_t *, kmp_uint64 *,
4678                           kmp_uint64 *, kmp_int64, kmp_uint64, kmp_uint64,
4679                           kmp_uint64, kmp_uint64, kmp_int64, kmp_uint64,
4680                           kmp_uint64,
4681 #if OMPT_SUPPORT
4682                           void *,
4683 #endif
4684                           void *);
4685 
4686 // Execute part of the taskloop submitted as a task.
4687 int __kmp_taskloop_task(int gtid, void *ptask) {
4688   __taskloop_params_t *p =
4689       (__taskloop_params_t *)((kmp_task_t *)ptask)->shareds;
4690   kmp_task_t *task = p->task;
4691   kmp_uint64 *lb = p->lb;
4692   kmp_uint64 *ub = p->ub;
4693   void *task_dup = p->task_dup;
4694   //  p_task_dup_t ptask_dup = (p_task_dup_t)task_dup;
4695   kmp_int64 st = p->st;
4696   kmp_uint64 ub_glob = p->ub_glob;
4697   kmp_uint64 num_tasks = p->num_tasks;
4698   kmp_uint64 grainsize = p->grainsize;
4699   kmp_uint64 extras = p->extras;
4700   kmp_int64 last_chunk = p->last_chunk;
4701   kmp_uint64 tc = p->tc;
4702   kmp_uint64 num_t_min = p->num_t_min;
4703 #if OMPT_SUPPORT
4704   void *codeptr_ra = p->codeptr_ra;
4705 #endif
4706 #if KMP_DEBUG
4707   kmp_taskdata_t *taskdata = KMP_TASK_TO_TASKDATA(task);
4708   KMP_DEBUG_ASSERT(task != NULL);
4709   KA_TRACE(20,
4710            ("__kmp_taskloop_task: T#%d, task %p: %lld tasks, grainsize"
4711             " %lld, extras %lld, last_chunk %lld, i=%lld,%lld(%d), dup %p\n",
4712             gtid, taskdata, num_tasks, grainsize, extras, last_chunk, *lb, *ub,
4713             st, task_dup));
4714 #endif
4715   KMP_DEBUG_ASSERT(num_tasks * 2 + 1 > num_t_min);
4716   if (num_tasks > num_t_min)
4717     __kmp_taskloop_recur(NULL, gtid, task, lb, ub, st, ub_glob, num_tasks,
4718                          grainsize, extras, last_chunk, tc, num_t_min,
4719 #if OMPT_SUPPORT
4720                          codeptr_ra,
4721 #endif
4722                          task_dup);
4723   else
4724     __kmp_taskloop_linear(NULL, gtid, task, lb, ub, st, ub_glob, num_tasks,
4725                           grainsize, extras, last_chunk, tc,
4726 #if OMPT_SUPPORT
4727                           codeptr_ra,
4728 #endif
4729                           task_dup);
4730 
4731   KA_TRACE(40, ("__kmp_taskloop_task(exit): T#%d\n", gtid));
4732   return 0;
4733 }
4734 
4735 // Schedule part of the taskloop as a task,
4736 // execute the rest of the taskloop.
4737 //
4738 // loc        Source location information
4739 // gtid       Global thread ID
4740 // task       Pattern task, exposes the loop iteration range
4741 // lb         Pointer to loop lower bound in task structure
4742 // ub         Pointer to loop upper bound in task structure
4743 // st         Loop stride
4744 // ub_glob    Global upper bound (used for lastprivate check)
4745 // num_tasks  Number of tasks to execute
4746 // grainsize  Number of loop iterations per task
4747 // extras     Number of chunks with grainsize+1 iterations
4748 // last_chunk Reduction of grainsize for last task
4749 // tc         Iterations count
4750 // num_t_min  Threshold to launch tasks recursively
4751 // task_dup   Tasks duplication routine
4752 // codeptr_ra Return address for OMPT events
4753 void __kmp_taskloop_recur(ident_t *loc, int gtid, kmp_task_t *task,
4754                           kmp_uint64 *lb, kmp_uint64 *ub, kmp_int64 st,
4755                           kmp_uint64 ub_glob, kmp_uint64 num_tasks,
4756                           kmp_uint64 grainsize, kmp_uint64 extras,
4757                           kmp_int64 last_chunk, kmp_uint64 tc,
4758                           kmp_uint64 num_t_min,
4759 #if OMPT_SUPPORT
4760                           void *codeptr_ra,
4761 #endif
4762                           void *task_dup) {
4763   kmp_taskdata_t *taskdata = KMP_TASK_TO_TASKDATA(task);
4764   KMP_DEBUG_ASSERT(task != NULL);
4765   KMP_DEBUG_ASSERT(num_tasks > num_t_min);
4766   KA_TRACE(20,
4767            ("__kmp_taskloop_recur: T#%d, task %p: %lld tasks, grainsize"
4768             " %lld, extras %lld, last_chunk %lld, i=%lld,%lld(%d), dup %p\n",
4769             gtid, taskdata, num_tasks, grainsize, extras, last_chunk, *lb, *ub,
4770             st, task_dup));
4771   p_task_dup_t ptask_dup = (p_task_dup_t)task_dup;
4772   kmp_uint64 lower = *lb;
4773   kmp_info_t *thread = __kmp_threads[gtid];
4774   //  kmp_taskdata_t *current_task = thread->th.th_current_task;
4775   kmp_task_t *next_task;
4776   size_t lower_offset =
4777       (char *)lb - (char *)task; // remember offset of lb in the task structure
4778   size_t upper_offset =
4779       (char *)ub - (char *)task; // remember offset of ub in the task structure
4780 
4781   KMP_DEBUG_ASSERT(tc == num_tasks * grainsize +
4782                              (last_chunk < 0 ? last_chunk : extras));
4783   KMP_DEBUG_ASSERT(num_tasks > extras);
4784   KMP_DEBUG_ASSERT(num_tasks > 0);
4785 
4786   // split the loop in two halves
4787   kmp_uint64 lb1, ub0, tc0, tc1, ext0, ext1;
4788   kmp_int64 last_chunk0 = 0, last_chunk1 = 0;
4789   kmp_uint64 gr_size0 = grainsize;
4790   kmp_uint64 n_tsk0 = num_tasks >> 1; // num_tasks/2 to execute
4791   kmp_uint64 n_tsk1 = num_tasks - n_tsk0; // to schedule as a task
4792   if (last_chunk < 0) {
4793     ext0 = ext1 = 0;
4794     last_chunk1 = last_chunk;
4795     tc0 = grainsize * n_tsk0;
4796     tc1 = tc - tc0;
4797   } else if (n_tsk0 <= extras) {
4798     gr_size0++; // integrate extras into grainsize
4799     ext0 = 0; // no extra iters in 1st half
4800     ext1 = extras - n_tsk0; // remaining extras
4801     tc0 = gr_size0 * n_tsk0;
4802     tc1 = tc - tc0;
4803   } else { // n_tsk0 > extras
4804     ext1 = 0; // no extra iters in 2nd half
4805     ext0 = extras;
4806     tc1 = grainsize * n_tsk1;
4807     tc0 = tc - tc1;
4808   }
4809   ub0 = lower + st * (tc0 - 1);
4810   lb1 = ub0 + st;
4811 
4812   // create pattern task for 2nd half of the loop
4813   next_task = __kmp_task_dup_alloc(thread, task); // duplicate the task
4814   // adjust lower bound (upper bound is not changed) for the 2nd half
4815   *(kmp_uint64 *)((char *)next_task + lower_offset) = lb1;
4816   if (ptask_dup != NULL) // construct firstprivates, etc.
4817     ptask_dup(next_task, task, 0);
4818   *ub = ub0; // adjust upper bound for the 1st half
4819 
4820   // create auxiliary task for 2nd half of the loop
4821   // make sure new task has same parent task as the pattern task
4822   kmp_taskdata_t *current_task = thread->th.th_current_task;
4823   thread->th.th_current_task = taskdata->td_parent;
4824   kmp_task_t *new_task =
4825       __kmpc_omp_task_alloc(loc, gtid, 1, 3 * sizeof(void *),
4826                             sizeof(__taskloop_params_t), &__kmp_taskloop_task);
4827   // restore current task
4828   thread->th.th_current_task = current_task;
4829   __taskloop_params_t *p = (__taskloop_params_t *)new_task->shareds;
4830   p->task = next_task;
4831   p->lb = (kmp_uint64 *)((char *)next_task + lower_offset);
4832   p->ub = (kmp_uint64 *)((char *)next_task + upper_offset);
4833   p->task_dup = task_dup;
4834   p->st = st;
4835   p->ub_glob = ub_glob;
4836   p->num_tasks = n_tsk1;
4837   p->grainsize = grainsize;
4838   p->extras = ext1;
4839   p->last_chunk = last_chunk1;
4840   p->tc = tc1;
4841   p->num_t_min = num_t_min;
4842 #if OMPT_SUPPORT
4843   p->codeptr_ra = codeptr_ra;
4844 #endif
4845 
4846 #if OMPT_SUPPORT
4847   // schedule new task with correct return address for OMPT events
4848   __kmp_omp_taskloop_task(NULL, gtid, new_task, codeptr_ra);
4849 #else
4850   __kmp_omp_task(gtid, new_task, true); // schedule new task
4851 #endif
4852 
4853   // execute the 1st half of current subrange
4854   if (n_tsk0 > num_t_min)
4855     __kmp_taskloop_recur(loc, gtid, task, lb, ub, st, ub_glob, n_tsk0, gr_size0,
4856                          ext0, last_chunk0, tc0, num_t_min,
4857 #if OMPT_SUPPORT
4858                          codeptr_ra,
4859 #endif
4860                          task_dup);
4861   else
4862     __kmp_taskloop_linear(loc, gtid, task, lb, ub, st, ub_glob, n_tsk0,
4863                           gr_size0, ext0, last_chunk0, tc0,
4864 #if OMPT_SUPPORT
4865                           codeptr_ra,
4866 #endif
4867                           task_dup);
4868 
4869   KA_TRACE(40, ("__kmp_taskloop_recur(exit): T#%d\n", gtid));
4870 }
4871 
4872 static void __kmp_taskloop(ident_t *loc, int gtid, kmp_task_t *task, int if_val,
4873                            kmp_uint64 *lb, kmp_uint64 *ub, kmp_int64 st,
4874                            int nogroup, int sched, kmp_uint64 grainsize,
4875                            int modifier, void *task_dup) {
4876   kmp_taskdata_t *taskdata = KMP_TASK_TO_TASKDATA(task);
4877   KMP_DEBUG_ASSERT(task != NULL);
4878   if (nogroup == 0) {
4879 #if OMPT_SUPPORT && OMPT_OPTIONAL
4880     OMPT_STORE_RETURN_ADDRESS(gtid);
4881 #endif
4882     __kmpc_taskgroup(loc, gtid);
4883   }
4884 
4885   // =========================================================================
4886   // calculate loop parameters
4887   kmp_taskloop_bounds_t task_bounds(task, lb, ub);
4888   kmp_uint64 tc;
4889   // compiler provides global bounds here
4890   kmp_uint64 lower = task_bounds.get_lb();
4891   kmp_uint64 upper = task_bounds.get_ub();
4892   kmp_uint64 ub_glob = upper; // global upper used to calc lastprivate flag
4893   kmp_uint64 num_tasks = 0, extras = 0;
4894   kmp_int64 last_chunk =
4895       0; // reduce grainsize of last task by last_chunk in strict mode
4896   kmp_uint64 num_tasks_min = __kmp_taskloop_min_tasks;
4897   kmp_info_t *thread = __kmp_threads[gtid];
4898   kmp_taskdata_t *current_task = thread->th.th_current_task;
4899 
4900   KA_TRACE(20, ("__kmp_taskloop: T#%d, task %p, lb %lld, ub %lld, st %lld, "
4901                 "grain %llu(%d, %d), dup %p\n",
4902                 gtid, taskdata, lower, upper, st, grainsize, sched, modifier,
4903                 task_dup));
4904 
4905   // compute trip count
4906   if (st == 1) { // most common case
4907     tc = upper - lower + 1;
4908   } else if (st < 0) {
4909     tc = (lower - upper) / (-st) + 1;
4910   } else { // st > 0
4911     tc = (upper - lower) / st + 1;
4912   }
4913   if (tc == 0) {
4914     KA_TRACE(20, ("__kmp_taskloop(exit): T#%d zero-trip loop\n", gtid));
4915     // free the pattern task and exit
4916     __kmp_task_start(gtid, task, current_task);
4917     // do not execute anything for zero-trip loop
4918     __kmp_task_finish<false>(gtid, task, current_task);
4919     return;
4920   }
4921 
4922 #if OMPT_SUPPORT && OMPT_OPTIONAL
4923   ompt_team_info_t *team_info = __ompt_get_teaminfo(0, NULL);
4924   ompt_task_info_t *task_info = __ompt_get_task_info_object(0);
4925   if (ompt_enabled.ompt_callback_work) {
4926     ompt_callbacks.ompt_callback(ompt_callback_work)(
4927         ompt_work_taskloop, ompt_scope_begin, &(team_info->parallel_data),
4928         &(task_info->task_data), tc, OMPT_GET_RETURN_ADDRESS(0));
4929   }
4930 #endif
4931 
4932   if (num_tasks_min == 0)
4933     // TODO: can we choose better default heuristic?
4934     num_tasks_min =
4935         KMP_MIN(thread->th.th_team_nproc * 10, INITIAL_TASK_DEQUE_SIZE);
4936 
4937   // compute num_tasks/grainsize based on the input provided
4938   switch (sched) {
4939   case 0: // no schedule clause specified, we can choose the default
4940     // let's try to schedule (team_size*10) tasks
4941     grainsize = thread->th.th_team_nproc * 10;
4942     KMP_FALLTHROUGH();
4943   case 2: // num_tasks provided
4944     if (grainsize > tc) {
4945       num_tasks = tc; // too big num_tasks requested, adjust values
4946       grainsize = 1;
4947       extras = 0;
4948     } else {
4949       num_tasks = grainsize;
4950       grainsize = tc / num_tasks;
4951       extras = tc % num_tasks;
4952     }
4953     break;
4954   case 1: // grainsize provided
4955     if (grainsize > tc) {
4956       num_tasks = 1;
4957       grainsize = tc; // too big grainsize requested, adjust values
4958       extras = 0;
4959     } else {
4960       if (modifier) {
4961         num_tasks = (tc + grainsize - 1) / grainsize;
4962         last_chunk = tc - (num_tasks * grainsize);
4963         extras = 0;
4964       } else {
4965         num_tasks = tc / grainsize;
4966         // adjust grainsize for balanced distribution of iterations
4967         grainsize = tc / num_tasks;
4968         extras = tc % num_tasks;
4969       }
4970     }
4971     break;
4972   default:
4973     KMP_ASSERT2(0, "unknown scheduling of taskloop");
4974   }
4975 
4976   KMP_DEBUG_ASSERT(tc == num_tasks * grainsize +
4977                              (last_chunk < 0 ? last_chunk : extras));
4978   KMP_DEBUG_ASSERT(num_tasks > extras);
4979   KMP_DEBUG_ASSERT(num_tasks > 0);
4980   // =========================================================================
4981 
4982   // check if clause value first
4983   // Also require GOMP_taskloop to reduce to linear (taskdata->td_flags.native)
4984   if (if_val == 0) { // if(0) specified, mark task as serial
4985     taskdata->td_flags.task_serial = 1;
4986     taskdata->td_flags.tiedness = TASK_TIED; // AC: serial task cannot be untied
4987     // always start serial tasks linearly
4988     __kmp_taskloop_linear(loc, gtid, task, lb, ub, st, ub_glob, num_tasks,
4989                           grainsize, extras, last_chunk, tc,
4990 #if OMPT_SUPPORT
4991                           OMPT_GET_RETURN_ADDRESS(0),
4992 #endif
4993                           task_dup);
4994     // !taskdata->td_flags.native => currently force linear spawning of tasks
4995     // for GOMP_taskloop
4996   } else if (num_tasks > num_tasks_min && !taskdata->td_flags.native) {
4997     KA_TRACE(20, ("__kmp_taskloop: T#%d, go recursive: tc %llu, #tasks %llu"
4998                   "(%lld), grain %llu, extras %llu, last_chunk %lld\n",
4999                   gtid, tc, num_tasks, num_tasks_min, grainsize, extras,
5000                   last_chunk));
5001     __kmp_taskloop_recur(loc, gtid, task, lb, ub, st, ub_glob, num_tasks,
5002                          grainsize, extras, last_chunk, tc, num_tasks_min,
5003 #if OMPT_SUPPORT
5004                          OMPT_GET_RETURN_ADDRESS(0),
5005 #endif
5006                          task_dup);
5007   } else {
5008     KA_TRACE(20, ("__kmp_taskloop: T#%d, go linear: tc %llu, #tasks %llu"
5009                   "(%lld), grain %llu, extras %llu, last_chunk %lld\n",
5010                   gtid, tc, num_tasks, num_tasks_min, grainsize, extras,
5011                   last_chunk));
5012     __kmp_taskloop_linear(loc, gtid, task, lb, ub, st, ub_glob, num_tasks,
5013                           grainsize, extras, last_chunk, tc,
5014 #if OMPT_SUPPORT
5015                           OMPT_GET_RETURN_ADDRESS(0),
5016 #endif
5017                           task_dup);
5018   }
5019 
5020 #if OMPT_SUPPORT && OMPT_OPTIONAL
5021   if (ompt_enabled.ompt_callback_work) {
5022     ompt_callbacks.ompt_callback(ompt_callback_work)(
5023         ompt_work_taskloop, ompt_scope_end, &(team_info->parallel_data),
5024         &(task_info->task_data), tc, OMPT_GET_RETURN_ADDRESS(0));
5025   }
5026 #endif
5027 
5028   if (nogroup == 0) {
5029 #if OMPT_SUPPORT && OMPT_OPTIONAL
5030     OMPT_STORE_RETURN_ADDRESS(gtid);
5031 #endif
5032     __kmpc_end_taskgroup(loc, gtid);
5033   }
5034   KA_TRACE(20, ("__kmp_taskloop(exit): T#%d\n", gtid));
5035 }
5036 
5037 /*!
5038 @ingroup TASKING
5039 @param loc       Source location information
5040 @param gtid      Global thread ID
5041 @param task      Task structure
5042 @param if_val    Value of the if clause
5043 @param lb        Pointer to loop lower bound in task structure
5044 @param ub        Pointer to loop upper bound in task structure
5045 @param st        Loop stride
5046 @param nogroup   Flag, 1 if nogroup clause specified, 0 otherwise
5047 @param sched     Schedule specified 0/1/2 for none/grainsize/num_tasks
5048 @param grainsize Schedule value if specified
5049 @param task_dup  Tasks duplication routine
5050 
5051 Execute the taskloop construct.
5052 */
5053 void __kmpc_taskloop(ident_t *loc, int gtid, kmp_task_t *task, int if_val,
5054                      kmp_uint64 *lb, kmp_uint64 *ub, kmp_int64 st, int nogroup,
5055                      int sched, kmp_uint64 grainsize, void *task_dup) {
5056   __kmp_assert_valid_gtid(gtid);
5057   KA_TRACE(20, ("__kmpc_taskloop(enter): T#%d\n", gtid));
5058   __kmp_taskloop(loc, gtid, task, if_val, lb, ub, st, nogroup, sched, grainsize,
5059                  0, task_dup);
5060   KA_TRACE(20, ("__kmpc_taskloop(exit): T#%d\n", gtid));
5061 }
5062 
5063 /*!
5064 @ingroup TASKING
5065 @param loc       Source location information
5066 @param gtid      Global thread ID
5067 @param task      Task structure
5068 @param if_val    Value of the if clause
5069 @param lb        Pointer to loop lower bound in task structure
5070 @param ub        Pointer to loop upper bound in task structure
5071 @param st        Loop stride
5072 @param nogroup   Flag, 1 if nogroup clause specified, 0 otherwise
5073 @param sched     Schedule specified 0/1/2 for none/grainsize/num_tasks
5074 @param grainsize Schedule value if specified
5075 @param modifer   Modifier 'strict' for sched, 1 if present, 0 otherwise
5076 @param task_dup  Tasks duplication routine
5077 
5078 Execute the taskloop construct.
5079 */
5080 void __kmpc_taskloop_5(ident_t *loc, int gtid, kmp_task_t *task, int if_val,
5081                        kmp_uint64 *lb, kmp_uint64 *ub, kmp_int64 st,
5082                        int nogroup, int sched, kmp_uint64 grainsize,
5083                        int modifier, void *task_dup) {
5084   __kmp_assert_valid_gtid(gtid);
5085   KA_TRACE(20, ("__kmpc_taskloop_5(enter): T#%d\n", gtid));
5086   __kmp_taskloop(loc, gtid, task, if_val, lb, ub, st, nogroup, sched, grainsize,
5087                  modifier, task_dup);
5088   KA_TRACE(20, ("__kmpc_taskloop_5(exit): T#%d\n", gtid));
5089 }
5090