LLVM OpenMP* Runtime Library
kmp_taskdeps.h
1 /*
2  * kmp_taskdeps.h
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 #ifndef KMP_TASKDEPS_H
14 #define KMP_TASKDEPS_H
15 
16 #include "kmp.h"
17 
18 #define KMP_ACQUIRE_DEPNODE(gtid, n) __kmp_acquire_lock(&(n)->dn.lock, (gtid))
19 #define KMP_RELEASE_DEPNODE(gtid, n) __kmp_release_lock(&(n)->dn.lock, (gtid))
20 
21 static inline void __kmp_node_deref(kmp_info_t *thread, kmp_depnode_t *node) {
22  if (!node)
23  return;
24 
25  kmp_int32 n = KMP_ATOMIC_DEC(&node->dn.nrefs) - 1;
26  KMP_DEBUG_ASSERT(n >= 0);
27  if (n == 0) {
28 #if USE_ITT_BUILD && USE_ITT_NOTIFY
29  __itt_sync_destroy(node);
30 #endif
31  KMP_ASSERT(node->dn.nrefs == 0);
32 #if USE_FAST_MEMORY
33  __kmp_fast_free(thread, node);
34 #else
35  __kmp_thread_free(thread, node);
36 #endif
37  }
38 }
39 
40 static inline void __kmp_depnode_list_free(kmp_info_t *thread,
41  kmp_depnode_list *list) {
42  kmp_depnode_list *next;
43 
44  for (; list; list = next) {
45  next = list->next;
46 
47  __kmp_node_deref(thread, list->node);
48 #if USE_FAST_MEMORY
49  __kmp_fast_free(thread, list);
50 #else
51  __kmp_thread_free(thread, list);
52 #endif
53  }
54 }
55 
56 static inline void __kmp_dephash_free_entries(kmp_info_t *thread,
57  kmp_dephash_t *h) {
58  for (size_t i = 0; i < h->size; i++) {
59  if (h->buckets[i]) {
60  kmp_dephash_entry_t *next;
61  for (kmp_dephash_entry_t *entry = h->buckets[i]; entry; entry = next) {
62  next = entry->next_in_bucket;
63  __kmp_depnode_list_free(thread, entry->last_set);
64  __kmp_depnode_list_free(thread, entry->prev_set);
65  __kmp_node_deref(thread, entry->last_out);
66  if (entry->mtx_lock) {
67  __kmp_destroy_lock(entry->mtx_lock);
68  __kmp_free(entry->mtx_lock);
69  }
70 #if USE_FAST_MEMORY
71  __kmp_fast_free(thread, entry);
72 #else
73  __kmp_thread_free(thread, entry);
74 #endif
75  }
76  h->buckets[i] = 0;
77  }
78  }
79  __kmp_node_deref(thread, h->last_all);
80  h->last_all = NULL;
81 }
82 
83 static inline void __kmp_dephash_free(kmp_info_t *thread, kmp_dephash_t *h) {
84  __kmp_dephash_free_entries(thread, h);
85 #if USE_FAST_MEMORY
86  __kmp_fast_free(thread, h);
87 #else
88  __kmp_thread_free(thread, h);
89 #endif
90 }
91 
92 extern void __kmpc_give_task(kmp_task_t *ptask, kmp_int32 start);
93 
94 static inline void __kmp_release_deps(kmp_int32 gtid, kmp_taskdata_t *task) {
95 
96 #if OMPX_TASKGRAPH
97  if (task->is_taskgraph && !(__kmp_tdg_is_recording(task->tdg->tdg_status))) {
98  kmp_node_info_t *TaskInfo = &(task->tdg->record_map[task->td_task_id]);
99 
100  for (int i = 0; i < TaskInfo->nsuccessors; i++) {
101  kmp_int32 successorNumber = TaskInfo->successors[i];
102  kmp_node_info_t *successor = &(task->tdg->record_map[successorNumber]);
103  kmp_int32 npredecessors = KMP_ATOMIC_DEC(&successor->npredecessors_counter) - 1;
104  if (successor->task != nullptr && npredecessors == 0) {
105  __kmp_omp_task(gtid, successor->task, false);
106  }
107  }
108  return;
109  }
110 #endif
111 
112  kmp_info_t *thread = __kmp_threads[gtid];
113  kmp_depnode_t *node = task->td_depnode;
114 
115  // Check mutexinoutset dependencies, release locks
116  if (UNLIKELY(node && (node->dn.mtx_num_locks < 0))) {
117  // negative num_locks means all locks were acquired
118  node->dn.mtx_num_locks = -node->dn.mtx_num_locks;
119  for (int i = node->dn.mtx_num_locks - 1; i >= 0; --i) {
120  KMP_DEBUG_ASSERT(node->dn.mtx_locks[i] != NULL);
121  __kmp_release_lock(node->dn.mtx_locks[i], gtid);
122  }
123  }
124 
125  if (task->td_dephash) {
126  KA_TRACE(
127  40, ("__kmp_release_deps: T#%d freeing dependencies hash of task %p.\n",
128  gtid, task));
129  __kmp_dephash_free(thread, task->td_dephash);
130  task->td_dephash = NULL;
131  }
132 
133  if (!node)
134  return;
135 
136  KA_TRACE(20, ("__kmp_release_deps: T#%d notifying successors of task %p.\n",
137  gtid, task));
138 
139  KMP_ACQUIRE_DEPNODE(gtid, node);
140 #if OMPX_TASKGRAPH
141  if (!task->is_taskgraph ||
142  (task->is_taskgraph && !__kmp_tdg_is_recording(task->tdg->tdg_status)))
143 #endif
144  node->dn.task =
145  NULL; // mark this task as finished, so no new dependencies are generated
146  KMP_RELEASE_DEPNODE(gtid, node);
147 
148  kmp_depnode_list_t *next;
149  kmp_taskdata_t *next_taskdata;
150  for (kmp_depnode_list_t *p = node->dn.successors; p; p = next) {
151  kmp_depnode_t *successor = p->node;
152 #if USE_ITT_BUILD && USE_ITT_NOTIFY
153  __itt_sync_releasing(successor);
154 #endif
155  kmp_int32 npredecessors = KMP_ATOMIC_DEC(&successor->dn.npredecessors) - 1;
156 
157  // successor task can be NULL for wait_depends or because deps are still
158  // being processed
159  if (npredecessors == 0) {
160 #if USE_ITT_BUILD && USE_ITT_NOTIFY
161  __itt_sync_acquired(successor);
162 #endif
163  KMP_MB();
164  if (successor->dn.task) {
165  KA_TRACE(20, ("__kmp_release_deps: T#%d successor %p of %p scheduled "
166  "for execution.\n",
167  gtid, successor->dn.task, task));
168  // If a regular task depending on a hidden helper task, when the
169  // hidden helper task is done, the regular task should be executed by
170  // its encountering team.
171  if (KMP_HIDDEN_HELPER_THREAD(gtid)) {
172  // Hidden helper thread can only execute hidden helper tasks
173  KMP_ASSERT(task->td_flags.hidden_helper);
174  next_taskdata = KMP_TASK_TO_TASKDATA(successor->dn.task);
175  // If the dependent task is a regular task, we need to push to its
176  // encountering thread's queue; otherwise, it can be pushed to its own
177  // queue.
178  if (!next_taskdata->td_flags.hidden_helper) {
179  kmp_int32 encountering_gtid =
180  next_taskdata->td_alloc_thread->th.th_info.ds.ds_gtid;
181  kmp_int32 encountering_tid = __kmp_tid_from_gtid(encountering_gtid);
182  __kmpc_give_task(successor->dn.task, encountering_tid);
183  } else {
184  __kmp_omp_task(gtid, successor->dn.task, false);
185  }
186  } else {
187  __kmp_omp_task(gtid, successor->dn.task, false);
188  }
189  }
190  }
191 
192  next = p->next;
193  __kmp_node_deref(thread, p->node);
194 #if USE_FAST_MEMORY
195  __kmp_fast_free(thread, p);
196 #else
197  __kmp_thread_free(thread, p);
198 #endif
199  }
200 
201  __kmp_node_deref(thread, node);
202 
203  KA_TRACE(
204  20,
205  ("__kmp_release_deps: T#%d all successors of %p notified of completion\n",
206  gtid, task));
207 }
208 
209 #endif // KMP_TASKDEPS_H