LLVM OpenMP* Runtime Library
kmp_taskdeps.h
1 /*
2  * kmp_taskdeps.h
3  */
4 
5 
6 //===----------------------------------------------------------------------===//
7 //
8 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
9 // See https://llvm.org/LICENSE.txt for license information.
10 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
11 //
12 //===----------------------------------------------------------------------===//
13 
14 
15 #ifndef KMP_TASKDEPS_H
16 #define KMP_TASKDEPS_H
17 
18 #include "kmp.h"
19 
20 #define KMP_ACQUIRE_DEPNODE(gtid, n) __kmp_acquire_lock(&(n)->dn.lock, (gtid))
21 #define KMP_RELEASE_DEPNODE(gtid, n) __kmp_release_lock(&(n)->dn.lock, (gtid))
22 
23 static inline void __kmp_node_deref(kmp_info_t *thread, kmp_depnode_t *node) {
24  if (!node)
25  return;
26 
27  kmp_int32 n = KMP_ATOMIC_DEC(&node->dn.nrefs) - 1;
28  if (n == 0) {
29  KMP_ASSERT(node->dn.nrefs == 0);
30 #if USE_FAST_MEMORY
31  __kmp_fast_free(thread, node);
32 #else
33  __kmp_thread_free(thread, node);
34 #endif
35  }
36 }
37 
38 static inline void __kmp_depnode_list_free(kmp_info_t *thread,
39  kmp_depnode_list *list) {
40  kmp_depnode_list *next;
41 
42  for (; list; list = next) {
43  next = list->next;
44 
45  __kmp_node_deref(thread, list->node);
46 #if USE_FAST_MEMORY
47  __kmp_fast_free(thread, list);
48 #else
49  __kmp_thread_free(thread, list);
50 #endif
51  }
52 }
53 
54 static inline void __kmp_dephash_free_entries(kmp_info_t *thread,
55  kmp_dephash_t *h) {
56  for (size_t i = 0; i < h->size; i++) {
57  if (h->buckets[i]) {
58  kmp_dephash_entry_t *next;
59  for (kmp_dephash_entry_t *entry = h->buckets[i]; entry; entry = next) {
60  next = entry->next_in_bucket;
61  __kmp_depnode_list_free(thread, entry->last_ins);
62  __kmp_depnode_list_free(thread, entry->last_mtxs);
63  __kmp_node_deref(thread, entry->last_out);
64  if (entry->mtx_lock) {
65  __kmp_destroy_lock(entry->mtx_lock);
66  __kmp_free(entry->mtx_lock);
67  }
68 #if USE_FAST_MEMORY
69  __kmp_fast_free(thread, entry);
70 #else
71  __kmp_thread_free(thread, entry);
72 #endif
73  }
74  h->buckets[i] = 0;
75  }
76  }
77 }
78 
79 static inline void __kmp_dephash_free(kmp_info_t *thread, kmp_dephash_t *h) {
80  __kmp_dephash_free_entries(thread, h);
81 #if USE_FAST_MEMORY
82  __kmp_fast_free(thread, h);
83 #else
84  __kmp_thread_free(thread, h);
85 #endif
86 }
87 
88 static inline void __kmp_release_deps(kmp_int32 gtid, kmp_taskdata_t *task) {
89  kmp_info_t *thread = __kmp_threads[gtid];
90  kmp_depnode_t *node = task->td_depnode;
91 
92  // Check mutexinoutset dependencies, release locks
93  if (UNLIKELY(node && (node->dn.mtx_num_locks < 0))) {
94  // negative num_locks means all locks were acquired
95  node->dn.mtx_num_locks = -node->dn.mtx_num_locks;
96  for (int i = node->dn.mtx_num_locks - 1; i >= 0; --i) {
97  KMP_DEBUG_ASSERT(node->dn.mtx_locks[i] != NULL);
98  __kmp_release_lock(node->dn.mtx_locks[i], gtid);
99  }
100  }
101 
102  if (task->td_dephash) {
103  KA_TRACE(
104  40, ("__kmp_release_deps: T#%d freeing dependencies hash of task %p.\n",
105  gtid, task));
106  __kmp_dephash_free(thread, task->td_dephash);
107  task->td_dephash = NULL;
108  }
109 
110  if (!node)
111  return;
112 
113  KA_TRACE(20, ("__kmp_release_deps: T#%d notifying successors of task %p.\n",
114  gtid, task));
115 
116  KMP_ACQUIRE_DEPNODE(gtid, node);
117  node->dn.task =
118  NULL; // mark this task as finished, so no new dependencies are generated
119  KMP_RELEASE_DEPNODE(gtid, node);
120 
121  kmp_depnode_list_t *next;
122  kmp_taskdata_t *next_taskdata;
123  for (kmp_depnode_list_t *p = node->dn.successors; p; p = next) {
124  kmp_depnode_t *successor = p->node;
125  kmp_int32 npredecessors = KMP_ATOMIC_DEC(&successor->dn.npredecessors) - 1;
126 
127  // successor task can be NULL for wait_depends or because deps are still
128  // being processed
129  if (npredecessors == 0) {
130  KMP_MB();
131  if (successor->dn.task) {
132  KA_TRACE(20, ("__kmp_release_deps: T#%d successor %p of %p scheduled "
133  "for execution.\n",
134  gtid, successor->dn.task, task));
135  // If a regular task depending on a hidden helper task, when the
136  // hidden helper task is done, the regular task should be executed by
137  // its encountering team.
138  if (KMP_HIDDEN_HELPER_THREAD(gtid)) {
139  // Hidden helper thread can only execute hidden helper tasks
140  KMP_ASSERT(task->td_flags.hidden_helper);
141  next_taskdata = KMP_TASK_TO_TASKDATA(successor->dn.task);
142  // If the dependent task is a regular task, we need to push to its
143  // encountering thread's queue; otherwise, it can be pushed to its own
144  // queue.
145  if (!next_taskdata->td_flags.hidden_helper) {
146  __kmp_omp_task(task->encountering_gtid, successor->dn.task, false);
147  } else {
148  __kmp_omp_task(gtid, successor->dn.task, false);
149  }
150  } else {
151  __kmp_omp_task(gtid, successor->dn.task, false);
152  }
153  }
154  }
155 
156  next = p->next;
157  __kmp_node_deref(thread, p->node);
158 #if USE_FAST_MEMORY
159  __kmp_fast_free(thread, p);
160 #else
161  __kmp_thread_free(thread, p);
162 #endif
163  }
164 
165  __kmp_node_deref(thread, node);
166 
167  KA_TRACE(
168  20,
169  ("__kmp_release_deps: T#%d all successors of %p notified of completion\n",
170  gtid, task));
171 }
172 
173 #endif // KMP_TASKDEPS_H