1 /* Copyright (C) 2015-2018 Free Software Foundation, Inc. 2 Contributed by Aldy Hernandez <aldyh@redhat.com>. 3 4 This file is part of the GNU Offloading and Multi Processing Library 5 (libgomp). 6 7 Libgomp is free software; you can redistribute it and/or modify it 8 under the terms of the GNU General Public License as published by 9 the Free Software Foundation; either version 3, or (at your option) 10 any later version. 11 12 Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY 13 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS 14 FOR A PARTICULAR PURPOSE. See the GNU General Public License for 15 more details. 16 17 Under Section 7 of GPL version 3, you are granted additional 18 permissions described in the GCC Runtime Library Exception, version 19 3.1, as published by the Free Software Foundation. 20 21 You should have received a copy of the GNU General Public License and 22 a copy of the GCC Runtime Library Exception along with this program; 23 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 24 <http://www.gnu.org/licenses/>. */ 25 26 /* Priority queue implementation of GOMP tasks. */ 27 28 #include "libgomp.h" 29 30 #if _LIBGOMP_CHECKING_ 31 #include <stdio.h> 32 33 /* Sanity check to verify whether a TASK is in LIST. Return TRUE if 34 found, FALSE otherwise. 35 36 TYPE is the type of priority queue this task resides in. */ 37 38 static inline bool 39 priority_queue_task_in_list_p (enum priority_queue_type type, 40 struct priority_list *list, 41 struct gomp_task *task) 42 { 43 struct priority_node *p = list->tasks; 44 do 45 { 46 if (priority_node_to_task (type, p) == task) 47 return true; 48 p = p->next; 49 } 50 while (p != list->tasks); 51 return false; 52 } 53 54 /* Tree version of priority_queue_task_in_list_p. */ 55 56 static inline bool 57 priority_queue_task_in_tree_p (enum priority_queue_type type, 58 struct priority_queue *head, 59 struct gomp_task *task) 60 { 61 struct priority_list *list 62 = priority_queue_lookup_priority (head, task->priority); 63 if (!list) 64 return false; 65 return priority_queue_task_in_list_p (type, list, task); 66 } 67 68 /* Generic version of priority_queue_task_in_list_p that works for 69 trees or lists. */ 70 71 bool 72 priority_queue_task_in_queue_p (enum priority_queue_type type, 73 struct priority_queue *head, 74 struct gomp_task *task) 75 { 76 if (priority_queue_empty_p (head, MEMMODEL_RELAXED)) 77 return false; 78 if (priority_queue_multi_p (head)) 79 return priority_queue_task_in_tree_p (type, head, task); 80 else 81 return priority_queue_task_in_list_p (type, &head->l, task); 82 } 83 84 /* Sanity check LIST to make sure the tasks therein are in the right 85 order. LIST is a priority list of type TYPE. 86 87 The expected order is that GOMP_TASK_WAITING tasks come before 88 GOMP_TASK_TIED/GOMP_TASK_ASYNC_RUNNING ones. 89 90 If CHECK_DEPS is TRUE, we also check that parent_depends_on WAITING 91 tasks come before !parent_depends_on WAITING tasks. This is only 92 applicable to the children queue, and the caller is expected to 93 ensure that we are verifying the children queue. */ 94 95 static void 96 priority_list_verify (enum priority_queue_type type, 97 struct priority_list *list, bool check_deps) 98 { 99 bool seen_tied = false; 100 bool seen_plain_waiting = false; 101 struct priority_node *p = list->tasks; 102 while (1) 103 { 104 struct gomp_task *t = priority_node_to_task (type, p); 105 if (seen_tied && t->kind == GOMP_TASK_WAITING) 106 gomp_fatal ("priority_queue_verify: WAITING task after TIED"); 107 if (t->kind >= GOMP_TASK_TIED) 108 seen_tied = true; 109 else if (check_deps && t->kind == GOMP_TASK_WAITING) 110 { 111 if (t->parent_depends_on) 112 { 113 if (seen_plain_waiting) 114 gomp_fatal ("priority_queue_verify: " 115 "parent_depends_on after !parent_depends_on"); 116 } 117 else 118 seen_plain_waiting = true; 119 } 120 p = p->next; 121 if (p == list->tasks) 122 break; 123 } 124 } 125 126 /* Callback type for priority_tree_verify_callback. */ 127 struct cbtype 128 { 129 enum priority_queue_type type; 130 bool check_deps; 131 }; 132 133 /* Verify every task in NODE. 134 135 Callback for splay_tree_foreach. */ 136 137 static void 138 priority_tree_verify_callback (prio_splay_tree_key key, void *data) 139 { 140 struct cbtype *cb = (struct cbtype *) data; 141 priority_list_verify (cb->type, &key->l, cb->check_deps); 142 } 143 144 /* Generic version of priority_list_verify. 145 146 Sanity check HEAD to make sure the tasks therein are in the right 147 order. The priority_queue holds tasks of type TYPE. 148 149 If CHECK_DEPS is TRUE, we also check that parent_depends_on WAITING 150 tasks come before !parent_depends_on WAITING tasks. This is only 151 applicable to the children queue, and the caller is expected to 152 ensure that we are verifying the children queue. */ 153 154 void 155 priority_queue_verify (enum priority_queue_type type, 156 struct priority_queue *head, bool check_deps) 157 { 158 if (priority_queue_empty_p (head, MEMMODEL_RELAXED)) 159 return; 160 if (priority_queue_multi_p (head)) 161 { 162 struct cbtype cb = { type, check_deps }; 163 prio_splay_tree_foreach (&head->t, 164 priority_tree_verify_callback, &cb); 165 } 166 else 167 priority_list_verify (type, &head->l, check_deps); 168 } 169 #endif /* _LIBGOMP_CHECKING_ */ 170 171 /* Remove NODE from priority queue HEAD, wherever it may be inside the 172 tree. HEAD contains tasks of type TYPE. */ 173 174 void 175 priority_tree_remove (enum priority_queue_type type, 176 struct priority_queue *head, 177 struct priority_node *node) 178 { 179 /* ?? The only reason this function is not inlined is because we 180 need to find the priority within gomp_task (which has not been 181 completely defined in the header file). If the lack of inlining 182 is a concern, we could pass the priority number as a 183 parameter, or we could move this to libgomp.h. */ 184 int priority = priority_node_to_task (type, node)->priority; 185 186 /* ?? We could avoid this lookup by keeping a pointer to the key in 187 the priority_node. */ 188 struct priority_list *list 189 = priority_queue_lookup_priority (head, priority); 190 #if _LIBGOMP_CHECKING_ 191 if (!list) 192 gomp_fatal ("Unable to find priority %d", priority); 193 #endif 194 /* If NODE was the last in its priority, clean up the priority. */ 195 if (priority_list_remove (list, node, MEMMODEL_RELAXED)) 196 { 197 prio_splay_tree_remove (&head->t, (prio_splay_tree_key) list); 198 list->tasks = NULL; 199 #if _LIBGOMP_CHECKING_ 200 memset (list, 0xaf, sizeof (*list)); 201 #endif 202 free (list); 203 } 204 } 205 206 /* Return the highest priority WAITING task in a splay tree NODE. If 207 there are no WAITING tasks available, return NULL. 208 209 NODE is a priority list containing tasks of type TYPE. 210 211 The right most node in a tree contains the highest priority. 212 Recurse down to find such a node. If the task at that max node is 213 not WAITING, bubble back up and look at the remaining tasks 214 in-order. */ 215 216 static struct gomp_task * 217 priority_tree_next_task_1 (enum priority_queue_type type, 218 prio_splay_tree_node node) 219 { 220 again: 221 if (!node) 222 return NULL; 223 struct gomp_task *ret = priority_tree_next_task_1 (type, node->right); 224 if (ret) 225 return ret; 226 ret = priority_node_to_task (type, node->key.l.tasks); 227 if (ret->kind == GOMP_TASK_WAITING) 228 return ret; 229 node = node->left; 230 goto again; 231 } 232 233 /* Return the highest priority WAITING task from within Q1 and Q2, 234 while giving preference to tasks from Q1. Q1 is a queue containing 235 items of type TYPE1. Q2 is a queue containing items of type TYPE2. 236 237 Since we are mostly interested in Q1, if there are no WAITING tasks 238 in Q1, we don't bother checking Q2, and just return NULL. 239 240 As a special case, Q2 can be NULL, in which case, we just choose 241 the highest priority WAITING task in Q1. This is an optimization 242 to speed up looking through only one queue. 243 244 If the returned task is chosen from Q1, *Q1_CHOSEN_P is set to 245 TRUE, otherwise it is set to FALSE. */ 246 247 struct gomp_task * 248 priority_tree_next_task (enum priority_queue_type type1, 249 struct priority_queue *q1, 250 enum priority_queue_type type2, 251 struct priority_queue *q2, 252 bool *q1_chosen_p) 253 { 254 struct gomp_task *t1 = priority_tree_next_task_1 (type1, q1->t.root); 255 if (!t1 256 /* Special optimization when only searching through one queue. */ 257 || !q2) 258 { 259 *q1_chosen_p = true; 260 return t1; 261 } 262 struct gomp_task *t2 = priority_tree_next_task_1 (type2, q2->t.root); 263 if (!t2 || t1->priority > t2->priority) 264 { 265 *q1_chosen_p = true; 266 return t1; 267 } 268 if (t2->priority > t1->priority) 269 { 270 *q1_chosen_p = false; 271 return t2; 272 } 273 /* If we get here, the priorities are the same, so we must look at 274 parent_depends_on to make our decision. */ 275 #if _LIBGOMP_CHECKING_ 276 if (t1 != t2) 277 gomp_fatal ("priority_tree_next_task: t1 != t2"); 278 #endif 279 if (t2->parent_depends_on && !t1->parent_depends_on) 280 { 281 *q1_chosen_p = false; 282 return t2; 283 } 284 *q1_chosen_p = true; 285 return t1; 286 } 287 288 /* Priority splay trees comparison function. */ 289 static inline int 290 prio_splay_compare (prio_splay_tree_key x, prio_splay_tree_key y) 291 { 292 if (x->l.priority == y->l.priority) 293 return 0; 294 return x->l.priority < y->l.priority ? -1 : 1; 295 } 296 297 /* Define another splay tree instantiation, for priority_list's. */ 298 #define splay_tree_prefix prio 299 #define splay_tree_c 300 #include "splay-tree.h" 301