9 #include "snapshot-interface.h"
11 #include "clockvector.h"
12 #include "cyclegraph.h"
15 #include "threads-model.h"
18 #define INITIAL_THREAD_ID 0
23 bug_message(const char *str) {
24 const char *fmt = " [BUG] %s\n";
25 msg = (char *)snapshot_malloc(strlen(fmt) + strlen(str));
26 sprintf(msg, fmt, str);
28 ~bug_message() { if (msg) snapshot_free(msg); }
31 void print() { model_print("%s", msg); }
37 * Structure for holding small ModelChecker members that should be snapshotted
39 struct model_snapshot_members {
40 model_snapshot_members() :
42 /* First thread created will have id INITIAL_THREAD_ID */
43 next_thread_id(INITIAL_THREAD_ID),
44 used_sequence_numbers(0),
49 failed_promise(false),
50 too_many_reads(false),
51 bad_synchronization(false),
55 ~model_snapshot_members() {
56 for (unsigned int i = 0; i < bugs.size(); i++)
61 ModelAction *current_action;
62 unsigned int next_thread_id;
63 modelclock_t used_sequence_numbers;
65 ModelAction *next_backtrack;
66 std::vector< bug_message *, SnapshotAlloc<bug_message *> > bugs;
67 struct execution_stats stats;
70 /** @brief Incorrectly-ordered synchronization was made */
71 bool bad_synchronization;
77 /** @brief Constructor */
78 ModelChecker::ModelChecker(struct model_params params) :
79 /* Initialize default scheduler */
81 scheduler(new Scheduler()),
83 earliest_diverge(NULL),
84 action_trace(new action_list_t()),
85 thread_map(new HashTable<int, Thread *, int>()),
86 obj_map(new HashTable<const void *, action_list_t *, uintptr_t, 4>()),
87 lock_waiters_map(new HashTable<const void *, action_list_t *, uintptr_t, 4>()),
88 condvar_waiters_map(new HashTable<const void *, action_list_t *, uintptr_t, 4>()),
89 obj_thrd_map(new HashTable<void *, std::vector<action_list_t> *, uintptr_t, 4 >()),
90 promises(new std::vector< Promise *, SnapshotAlloc<Promise *> >()),
91 futurevalues(new std::vector< struct PendingFutureValue, SnapshotAlloc<struct PendingFutureValue> >()),
92 pending_rel_seqs(new std::vector< struct release_seq *, SnapshotAlloc<struct release_seq *> >()),
93 thrd_last_action(new std::vector< ModelAction *, SnapshotAlloc<ModelAction *> >(1)),
94 node_stack(new NodeStack()),
95 priv(new struct model_snapshot_members()),
96 mo_graph(new CycleGraph())
98 /* Initialize a model-checker thread, for special ModelActions */
99 model_thread = new Thread(get_next_id());
100 thread_map->put(id_to_int(model_thread->get_id()), model_thread);
103 /** @brief Destructor */
104 ModelChecker::~ModelChecker()
106 for (unsigned int i = 0; i < get_num_threads(); i++)
107 delete thread_map->get(i);
112 delete lock_waiters_map;
113 delete condvar_waiters_map;
116 for (unsigned int i = 0; i < promises->size(); i++)
117 delete (*promises)[i];
120 delete pending_rel_seqs;
122 delete thrd_last_action;
129 static action_list_t * get_safe_ptr_action(HashTable<const void *, action_list_t *, uintptr_t, 4> * hash, void * ptr) {
130 action_list_t * tmp=hash->get(ptr);
132 tmp=new action_list_t();
138 static std::vector<action_list_t> * get_safe_ptr_vect_action(HashTable<void *, std::vector<action_list_t> *, uintptr_t, 4> * hash, void * ptr) {
139 std::vector<action_list_t> * tmp=hash->get(ptr);
141 tmp=new std::vector<action_list_t>();
148 * Restores user program to initial state and resets all model-checker data
151 void ModelChecker::reset_to_initial_state()
153 DEBUG("+++ Resetting to initial state +++\n");
154 node_stack->reset_execution();
156 /* Print all model-checker output before rollback */
159 snapshotObject->backTrackBeforeStep(0);
162 /** @return a thread ID for a new Thread */
163 thread_id_t ModelChecker::get_next_id()
165 return priv->next_thread_id++;
168 /** @return the number of user threads created during this execution */
169 unsigned int ModelChecker::get_num_threads() const
171 return priv->next_thread_id;
174 /** @return The currently executing Thread. */
175 Thread * ModelChecker::get_current_thread() const
177 return scheduler->get_current_thread();
180 /** @return a sequence number for a new ModelAction */
181 modelclock_t ModelChecker::get_next_seq_num()
183 return ++priv->used_sequence_numbers;
186 Node * ModelChecker::get_curr_node() const
188 return node_stack->get_head();
192 * @brief Choose the next thread to execute.
194 * This function chooses the next thread that should execute. It can force the
195 * adjacency of read/write portions of a RMW action, force THREAD_CREATE to be
196 * followed by a THREAD_START, or it can enforce execution replay/backtracking.
197 * The model-checker may have no preference regarding the next thread (i.e.,
198 * when exploring a new execution ordering), in which case this will return
200 * @param curr The current ModelAction. This action might guide the choice of
202 * @return The next thread to run. If the model-checker has no preference, NULL.
204 Thread * ModelChecker::get_next_thread(ModelAction *curr)
209 /* Do not split atomic actions. */
211 return thread_current();
212 /* The THREAD_CREATE action points to the created Thread */
213 else if (curr->get_type() == THREAD_CREATE)
214 return (Thread *)curr->get_location();
217 /* Have we completed exploring the preselected path? */
221 /* Else, we are trying to replay an execution */
222 ModelAction *next = node_stack->get_next()->get_action();
224 if (next == diverge) {
225 if (earliest_diverge == NULL || *diverge < *earliest_diverge)
226 earliest_diverge=diverge;
228 Node *nextnode = next->get_node();
229 Node *prevnode = nextnode->get_parent();
230 scheduler->update_sleep_set(prevnode);
232 /* Reached divergence point */
233 if (nextnode->increment_misc()) {
234 /* The next node will try to satisfy a different misc_index values. */
235 tid = next->get_tid();
236 node_stack->pop_restofstack(2);
237 } else if (nextnode->increment_promise()) {
238 /* The next node will try to satisfy a different set of promises. */
239 tid = next->get_tid();
240 node_stack->pop_restofstack(2);
241 } else if (nextnode->increment_read_from()) {
242 /* The next node will read from a different value. */
243 tid = next->get_tid();
244 node_stack->pop_restofstack(2);
245 } else if (nextnode->increment_future_value()) {
246 /* The next node will try to read from a different future value. */
247 tid = next->get_tid();
248 node_stack->pop_restofstack(2);
249 } else if (nextnode->increment_relseq_break()) {
250 /* The next node will try to resolve a release sequence differently */
251 tid = next->get_tid();
252 node_stack->pop_restofstack(2);
254 /* Make a different thread execute for next step */
255 scheduler->add_sleep(thread_map->get(id_to_int(next->get_tid())));
256 tid = prevnode->get_next_backtrack();
257 /* Make sure the backtracked thread isn't sleeping. */
258 node_stack->pop_restofstack(1);
259 if (diverge==earliest_diverge) {
260 earliest_diverge=prevnode->get_action();
263 /* The correct sleep set is in the parent node. */
266 DEBUG("*** Divergence point ***\n");
270 tid = next->get_tid();
272 DEBUG("*** ModelChecker chose next thread = %d ***\n", id_to_int(tid));
273 ASSERT(tid != THREAD_ID_T_NONE);
274 return thread_map->get(id_to_int(tid));
278 * We need to know what the next actions of all threads in the sleep
279 * set will be. This method computes them and stores the actions at
280 * the corresponding thread object's pending action.
283 void ModelChecker::execute_sleep_set() {
284 for(unsigned int i=0;i<get_num_threads();i++) {
285 thread_id_t tid=int_to_id(i);
286 Thread *thr=get_thread(tid);
287 if ( scheduler->get_enabled(thr) == THREAD_SLEEP_SET &&
288 thr->get_pending() == NULL ) {
289 thr->set_state(THREAD_RUNNING);
290 scheduler->next_thread(thr);
291 Thread::swap(&system_context, thr);
292 priv->current_action->set_sleep_flag();
293 thr->set_pending(priv->current_action);
296 priv->current_action = NULL;
299 void ModelChecker::wake_up_sleeping_actions(ModelAction * curr) {
300 for(unsigned int i=0;i<get_num_threads();i++) {
301 thread_id_t tid=int_to_id(i);
302 Thread *thr=get_thread(tid);
303 if ( scheduler->get_enabled(thr) == THREAD_SLEEP_SET ) {
304 ModelAction *pending_act=thr->get_pending();
305 if ((!curr->is_rmwr())&&pending_act->could_synchronize_with(curr)) {
306 //Remove this thread from sleep set
307 scheduler->remove_sleep(thr);
313 /** @brief Alert the model-checker that an incorrectly-ordered
314 * synchronization was made */
315 void ModelChecker::set_bad_synchronization()
317 priv->bad_synchronization = true;
320 bool ModelChecker::has_asserted() const
322 return priv->asserted;
325 void ModelChecker::set_assert()
327 priv->asserted = true;
331 * Check if we are in a deadlock. Should only be called at the end of an
332 * execution, although it should not give false positives in the middle of an
333 * execution (there should be some ENABLED thread).
335 * @return True if program is in a deadlock; false otherwise
337 bool ModelChecker::is_deadlocked() const
339 bool blocking_threads = false;
340 for (unsigned int i = 0; i < get_num_threads(); i++) {
341 thread_id_t tid = int_to_id(i);
344 Thread *t = get_thread(tid);
345 if (!t->is_model_thread() && t->get_pending())
346 blocking_threads = true;
348 return blocking_threads;
352 * Check if this is a complete execution. That is, have all thread completed
353 * execution (rather than exiting because sleep sets have forced a redundant
356 * @return True if the execution is complete.
358 bool ModelChecker::is_complete_execution() const
360 for (unsigned int i = 0; i < get_num_threads(); i++)
361 if (is_enabled(int_to_id(i)))
367 * @brief Assert a bug in the executing program.
369 * Use this function to assert any sort of bug in the user program. If the
370 * current trace is feasible (actually, a prefix of some feasible execution),
371 * then this execution will be aborted, printing the appropriate message. If
372 * the current trace is not yet feasible, the error message will be stashed and
373 * printed if the execution ever becomes feasible.
375 * @param msg Descriptive message for the bug (do not include newline char)
376 * @return True if bug is immediately-feasible
378 bool ModelChecker::assert_bug(const char *msg)
380 priv->bugs.push_back(new bug_message(msg));
382 if (isfeasibleprefix()) {
390 * @brief Assert a bug in the executing program, asserted by a user thread
391 * @see ModelChecker::assert_bug
392 * @param msg Descriptive message for the bug (do not include newline char)
394 void ModelChecker::assert_user_bug(const char *msg)
396 /* If feasible bug, bail out now */
398 switch_to_master(NULL);
401 /** @return True, if any bugs have been reported for this execution */
402 bool ModelChecker::have_bug_reports() const
404 return priv->bugs.size() != 0;
407 /** @brief Print bug report listing for this execution (if any bugs exist) */
408 void ModelChecker::print_bugs() const
410 if (have_bug_reports()) {
411 model_print("Bug report: %zu bug%s detected\n",
413 priv->bugs.size() > 1 ? "s" : "");
414 for (unsigned int i = 0; i < priv->bugs.size(); i++)
415 priv->bugs[i]->print();
420 * @brief Record end-of-execution stats
422 * Must be run when exiting an execution. Records various stats.
423 * @see struct execution_stats
425 void ModelChecker::record_stats()
428 if (!isfeasibleprefix())
429 stats.num_infeasible++;
430 else if (have_bug_reports())
431 stats.num_buggy_executions++;
432 else if (is_complete_execution())
433 stats.num_complete++;
435 stats.num_redundant++;
438 /** @brief Print execution stats */
439 void ModelChecker::print_stats() const
441 model_print("Number of complete, bug-free executions: %d\n", stats.num_complete);
442 model_print("Number of redundant executions: %d\n", stats.num_redundant);
443 model_print("Number of buggy executions: %d\n", stats.num_buggy_executions);
444 model_print("Number of infeasible executions: %d\n", stats.num_infeasible);
445 model_print("Total executions: %d\n", stats.num_total);
446 model_print("Total nodes created: %d\n", node_stack->get_total_nodes());
450 * @brief End-of-exeuction print
451 * @param printbugs Should any existing bugs be printed?
453 void ModelChecker::print_execution(bool printbugs) const
455 print_program_output();
457 if (DBG_ENABLED() || params.verbose) {
458 model_print("Earliest divergence point since last feasible execution:\n");
459 if (earliest_diverge)
460 earliest_diverge->print();
462 model_print("(Not set)\n");
468 /* Don't print invalid bugs */
477 * Queries the model-checker for more executions to explore and, if one
478 * exists, resets the model-checker state to execute a new execution.
480 * @return If there are more executions to explore, return true. Otherwise,
483 bool ModelChecker::next_execution()
486 /* Is this execution a feasible execution that's worth bug-checking? */
487 bool complete = isfeasibleprefix() && (is_complete_execution() ||
490 /* End-of-execution bug checks */
493 assert_bug("Deadlock detected");
501 if (DBG_ENABLED() || params.verbose || have_bug_reports())
502 print_execution(complete);
504 clear_program_output();
507 earliest_diverge = NULL;
509 if ((diverge = get_next_backtrack()) == NULL)
513 model_print("Next execution will diverge at:\n");
517 reset_to_initial_state();
521 ModelAction * ModelChecker::get_last_conflict(ModelAction *act)
523 switch (act->get_type()) {
527 /* Optimization: relaxed operations don't need backtracking */
528 if (act->is_relaxed())
530 /* linear search: from most recent to oldest */
531 action_list_t *list = get_safe_ptr_action(obj_map, act->get_location());
532 action_list_t::reverse_iterator rit;
533 for (rit = list->rbegin(); rit != list->rend(); rit++) {
534 ModelAction *prev = *rit;
535 if (prev->could_synchronize_with(act))
541 case ATOMIC_TRYLOCK: {
542 /* linear search: from most recent to oldest */
543 action_list_t *list = get_safe_ptr_action(obj_map, act->get_location());
544 action_list_t::reverse_iterator rit;
545 for (rit = list->rbegin(); rit != list->rend(); rit++) {
546 ModelAction *prev = *rit;
547 if (act->is_conflicting_lock(prev))
552 case ATOMIC_UNLOCK: {
553 /* linear search: from most recent to oldest */
554 action_list_t *list = get_safe_ptr_action(obj_map, act->get_location());
555 action_list_t::reverse_iterator rit;
556 for (rit = list->rbegin(); rit != list->rend(); rit++) {
557 ModelAction *prev = *rit;
558 if (!act->same_thread(prev)&&prev->is_failed_trylock())
564 /* linear search: from most recent to oldest */
565 action_list_t *list = get_safe_ptr_action(obj_map, act->get_location());
566 action_list_t::reverse_iterator rit;
567 for (rit = list->rbegin(); rit != list->rend(); rit++) {
568 ModelAction *prev = *rit;
569 if (!act->same_thread(prev)&&prev->is_failed_trylock())
571 if (!act->same_thread(prev)&&prev->is_notify())
577 case ATOMIC_NOTIFY_ALL:
578 case ATOMIC_NOTIFY_ONE: {
579 /* linear search: from most recent to oldest */
580 action_list_t *list = get_safe_ptr_action(obj_map, act->get_location());
581 action_list_t::reverse_iterator rit;
582 for (rit = list->rbegin(); rit != list->rend(); rit++) {
583 ModelAction *prev = *rit;
584 if (!act->same_thread(prev)&&prev->is_wait())
595 /** This method finds backtracking points where we should try to
596 * reorder the parameter ModelAction against.
598 * @param the ModelAction to find backtracking points for.
600 void ModelChecker::set_backtracking(ModelAction *act)
602 Thread *t = get_thread(act);
603 ModelAction * prev = get_last_conflict(act);
607 Node * node = prev->get_node()->get_parent();
609 int low_tid, high_tid;
610 if (node->is_enabled(t)) {
611 low_tid = id_to_int(act->get_tid());
612 high_tid = low_tid+1;
615 high_tid = get_num_threads();
618 for(int i = low_tid; i < high_tid; i++) {
619 thread_id_t tid = int_to_id(i);
621 /* Make sure this thread can be enabled here. */
622 if (i >= node->get_num_threads())
625 /* Don't backtrack into a point where the thread is disabled or sleeping. */
626 if (node->enabled_status(tid)!=THREAD_ENABLED)
629 /* Check if this has been explored already */
630 if (node->has_been_explored(tid))
633 /* See if fairness allows */
634 if (model->params.fairwindow != 0 && !node->has_priority(tid)) {
636 for(int t=0;t<node->get_num_threads();t++) {
637 thread_id_t tother=int_to_id(t);
638 if (node->is_enabled(tother) && node->has_priority(tother)) {
646 /* Cache the latest backtracking point */
647 if (!priv->next_backtrack || *prev > *priv->next_backtrack)
648 priv->next_backtrack = prev;
650 /* If this is a new backtracking point, mark the tree */
651 if (!node->set_backtrack(tid))
653 DEBUG("Setting backtrack: conflict = %d, instead tid = %d\n",
654 id_to_int(prev->get_tid()),
655 id_to_int(t->get_id()));
664 * Returns last backtracking point. The model checker will explore a different
665 * path for this point in the next execution.
666 * @return The ModelAction at which the next execution should diverge.
668 ModelAction * ModelChecker::get_next_backtrack()
670 ModelAction *next = priv->next_backtrack;
671 priv->next_backtrack = NULL;
676 * Processes a read or rmw model action.
677 * @param curr is the read model action to process.
678 * @param second_part_of_rmw is boolean that is true is this is the second action of a rmw.
679 * @return True if processing this read updates the mo_graph.
681 bool ModelChecker::process_read(ModelAction *curr, bool second_part_of_rmw)
683 uint64_t value = VALUE_NONE;
684 bool updated = false;
686 const ModelAction *reads_from = curr->get_node()->get_read_from();
687 if (reads_from != NULL) {
688 mo_graph->startChanges();
690 value = reads_from->get_value();
691 bool r_status = false;
693 if (!second_part_of_rmw) {
694 check_recency(curr, reads_from);
695 r_status = r_modification_order(curr, reads_from);
699 if (!second_part_of_rmw&&is_infeasible()&&(curr->get_node()->increment_read_from()||curr->get_node()->increment_future_value())) {
700 mo_graph->rollbackChanges();
701 priv->too_many_reads = false;
705 curr->read_from(reads_from);
706 mo_graph->commitChanges();
707 mo_check_promises(curr->get_tid(), reads_from);
710 } else if (!second_part_of_rmw) {
711 /* Read from future value */
712 value = curr->get_node()->get_future_value();
713 modelclock_t expiration = curr->get_node()->get_future_value_expiration();
714 curr->read_from(NULL);
715 Promise *valuepromise = new Promise(curr, value, expiration);
716 promises->push_back(valuepromise);
718 get_thread(curr)->set_return_value(value);
724 * Processes a lock, trylock, or unlock model action. @param curr is
725 * the read model action to process.
727 * The try lock operation checks whether the lock is taken. If not,
728 * it falls to the normal lock operation case. If so, it returns
731 * The lock operation has already been checked that it is enabled, so
732 * it just grabs the lock and synchronizes with the previous unlock.
734 * The unlock operation has to re-enable all of the threads that are
735 * waiting on the lock.
737 * @return True if synchronization was updated; false otherwise
739 bool ModelChecker::process_mutex(ModelAction *curr) {
740 std::mutex *mutex=NULL;
741 struct std::mutex_state *state=NULL;
743 if (curr->is_trylock() || curr->is_lock() || curr->is_unlock()) {
744 mutex = (std::mutex *)curr->get_location();
745 state = mutex->get_state();
746 } else if(curr->is_wait()) {
747 mutex = (std::mutex *)curr->get_value();
748 state = mutex->get_state();
751 switch (curr->get_type()) {
752 case ATOMIC_TRYLOCK: {
753 bool success = !state->islocked;
754 curr->set_try_lock(success);
756 get_thread(curr)->set_return_value(0);
759 get_thread(curr)->set_return_value(1);
761 //otherwise fall into the lock case
763 if (curr->get_cv()->getClock(state->alloc_tid) <= state->alloc_clock)
764 assert_bug("Lock access before initialization");
765 state->islocked = true;
766 ModelAction *unlock = get_last_unlock(curr);
767 //synchronize with the previous unlock statement
768 if (unlock != NULL) {
769 curr->synchronize_with(unlock);
774 case ATOMIC_UNLOCK: {
776 state->islocked = false;
777 //wake up the other threads
778 action_list_t *waiters = get_safe_ptr_action(lock_waiters_map, curr->get_location());
779 //activate all the waiting threads
780 for (action_list_t::iterator rit = waiters->begin(); rit != waiters->end(); rit++) {
781 scheduler->wake(get_thread(*rit));
788 state->islocked = false;
789 //wake up the other threads
790 action_list_t *waiters = get_safe_ptr_action(lock_waiters_map, (void *) curr->get_value());
791 //activate all the waiting threads
792 for (action_list_t::iterator rit = waiters->begin(); rit != waiters->end(); rit++) {
793 scheduler->wake(get_thread(*rit));
796 //check whether we should go to sleep or not...simulate spurious failures
797 if (curr->get_node()->get_misc()==0) {
798 get_safe_ptr_action(condvar_waiters_map, curr->get_location())->push_back(curr);
800 scheduler->sleep(get_current_thread());
804 case ATOMIC_NOTIFY_ALL: {
805 action_list_t *waiters = get_safe_ptr_action(condvar_waiters_map, curr->get_location());
806 //activate all the waiting threads
807 for (action_list_t::iterator rit = waiters->begin(); rit != waiters->end(); rit++) {
808 scheduler->wake(get_thread(*rit));
813 case ATOMIC_NOTIFY_ONE: {
814 action_list_t *waiters = get_safe_ptr_action(condvar_waiters_map, curr->get_location());
815 int wakeupthread=curr->get_node()->get_misc();
816 action_list_t::iterator it = waiters->begin();
817 advance(it, wakeupthread);
818 scheduler->wake(get_thread(*it));
830 * Process a write ModelAction
831 * @param curr The ModelAction to process
832 * @return True if the mo_graph was updated or promises were resolved
834 bool ModelChecker::process_write(ModelAction *curr)
836 bool updated_mod_order = w_modification_order(curr);
837 bool updated_promises = resolve_promises(curr);
839 if (promises->size() == 0) {
840 for (unsigned int i = 0; i < futurevalues->size(); i++) {
841 struct PendingFutureValue pfv = (*futurevalues)[i];
842 //Do more ambitious checks now that mo is more complete
843 if (mo_may_allow(pfv.writer, pfv.act)&&
844 pfv.act->get_node()->add_future_value(pfv.writer->get_value(), pfv.writer->get_seq_number()+params.maxfuturedelay) &&
845 (!priv->next_backtrack || *pfv.act > *priv->next_backtrack))
846 priv->next_backtrack = pfv.act;
848 futurevalues->resize(0);
851 mo_graph->commitChanges();
852 mo_check_promises(curr->get_tid(), curr);
854 get_thread(curr)->set_return_value(VALUE_NONE);
855 return updated_mod_order || updated_promises;
859 * @brief Process the current action for thread-related activity
861 * Performs current-action processing for a THREAD_* ModelAction. Proccesses
862 * may include setting Thread status, completing THREAD_FINISH/THREAD_JOIN
863 * synchronization, etc. This function is a no-op for non-THREAD actions
864 * (e.g., ATOMIC_{READ,WRITE,RMW,LOCK}, etc.)
866 * @param curr The current action
867 * @return True if synchronization was updated or a thread completed
869 bool ModelChecker::process_thread_action(ModelAction *curr)
871 bool updated = false;
873 switch (curr->get_type()) {
874 case THREAD_CREATE: {
875 Thread *th = (Thread *)curr->get_location();
876 th->set_creation(curr);
880 Thread *blocking = (Thread *)curr->get_location();
881 ModelAction *act = get_last_action(blocking->get_id());
882 curr->synchronize_with(act);
883 updated = true; /* trigger rel-seq checks */
886 case THREAD_FINISH: {
887 Thread *th = get_thread(curr);
888 while (!th->wait_list_empty()) {
889 ModelAction *act = th->pop_wait_list();
890 scheduler->wake(get_thread(act));
893 updated = true; /* trigger rel-seq checks */
897 check_promises(curr->get_tid(), NULL, curr->get_cv());
908 * @brief Process the current action for release sequence fixup activity
910 * Performs model-checker release sequence fixups for the current action,
911 * forcing a single pending release sequence to break (with a given, potential
912 * "loose" write) or to complete (i.e., synchronize). If a pending release
913 * sequence forms a complete release sequence, then we must perform the fixup
914 * synchronization, mo_graph additions, etc.
916 * @param curr The current action; must be a release sequence fixup action
917 * @param work_queue The work queue to which to add work items as they are
920 void ModelChecker::process_relseq_fixup(ModelAction *curr, work_queue_t *work_queue)
922 const ModelAction *write = curr->get_node()->get_relseq_break();
923 struct release_seq *sequence = pending_rel_seqs->back();
924 pending_rel_seqs->pop_back();
926 ModelAction *acquire = sequence->acquire;
927 const ModelAction *rf = sequence->rf;
928 const ModelAction *release = sequence->release;
932 ASSERT(release->same_thread(rf));
936 * @todo Forcing a synchronization requires that we set
937 * modification order constraints. For instance, we can't allow
938 * a fixup sequence in which two separate read-acquire
939 * operations read from the same sequence, where the first one
940 * synchronizes and the other doesn't. Essentially, we can't
941 * allow any writes to insert themselves between 'release' and
945 /* Must synchronize */
946 if (!acquire->synchronize_with(release)) {
947 set_bad_synchronization();
950 /* Re-check all pending release sequences */
951 work_queue->push_back(CheckRelSeqWorkEntry(NULL));
952 /* Re-check act for mo_graph edges */
953 work_queue->push_back(MOEdgeWorkEntry(acquire));
955 /* propagate synchronization to later actions */
956 action_list_t::reverse_iterator rit = action_trace->rbegin();
957 for (; (*rit) != acquire; rit++) {
958 ModelAction *propagate = *rit;
959 if (acquire->happens_before(propagate)) {
960 propagate->synchronize_with(acquire);
961 /* Re-check 'propagate' for mo_graph edges */
962 work_queue->push_back(MOEdgeWorkEntry(propagate));
966 /* Break release sequence with new edges:
967 * release --mo--> write --mo--> rf */
968 mo_graph->addEdge(release, write);
969 mo_graph->addEdge(write, rf);
972 /* See if we have realized a data race */
977 * Initialize the current action by performing one or more of the following
978 * actions, as appropriate: merging RMWR and RMWC/RMW actions, stepping forward
979 * in the NodeStack, manipulating backtracking sets, allocating and
980 * initializing clock vectors, and computing the promises to fulfill.
982 * @param curr The current action, as passed from the user context; may be
983 * freed/invalidated after the execution of this function, with a different
984 * action "returned" its place (pass-by-reference)
985 * @return True if curr is a newly-explored action; false otherwise
987 bool ModelChecker::initialize_curr_action(ModelAction **curr)
989 ModelAction *newcurr;
991 if ((*curr)->is_rmwc() || (*curr)->is_rmw()) {
992 newcurr = process_rmw(*curr);
995 if (newcurr->is_rmw())
996 compute_promises(newcurr);
1002 (*curr)->set_seq_number(get_next_seq_num());
1004 newcurr = node_stack->explore_action(*curr, scheduler->get_enabled_array());
1006 /* First restore type and order in case of RMW operation */
1007 if ((*curr)->is_rmwr())
1008 newcurr->copy_typeandorder(*curr);
1010 ASSERT((*curr)->get_location() == newcurr->get_location());
1011 newcurr->copy_from_new(*curr);
1013 /* Discard duplicate ModelAction; use action from NodeStack */
1016 /* Always compute new clock vector */
1017 newcurr->create_cv(get_parent_action(newcurr->get_tid()));
1020 return false; /* Action was explored previously */
1024 /* Always compute new clock vector */
1025 newcurr->create_cv(get_parent_action(newcurr->get_tid()));
1027 * Perform one-time actions when pushing new ModelAction onto
1030 if (newcurr->is_write())
1031 compute_promises(newcurr);
1032 else if (newcurr->is_relseq_fixup())
1033 compute_relseq_breakwrites(newcurr);
1034 else if (newcurr->is_wait())
1035 newcurr->get_node()->set_misc_max(2);
1036 else if (newcurr->is_notify_one()) {
1037 newcurr->get_node()->set_misc_max(get_safe_ptr_action(condvar_waiters_map, newcurr->get_location())->size());
1039 return true; /* This was a new ModelAction */
1044 * @brief Check whether a model action is enabled.
1046 * Checks whether a lock or join operation would be successful (i.e., is the
1047 * lock already locked, or is the joined thread already complete). If not, put
1048 * the action in a waiter list.
1050 * @param curr is the ModelAction to check whether it is enabled.
1051 * @return a bool that indicates whether the action is enabled.
1053 bool ModelChecker::check_action_enabled(ModelAction *curr) {
1054 if (curr->is_lock()) {
1055 std::mutex * lock = (std::mutex *)curr->get_location();
1056 struct std::mutex_state * state = lock->get_state();
1057 if (state->islocked) {
1058 //Stick the action in the appropriate waiting queue
1059 get_safe_ptr_action(lock_waiters_map, curr->get_location())->push_back(curr);
1062 } else if (curr->get_type() == THREAD_JOIN) {
1063 Thread *blocking = (Thread *)curr->get_location();
1064 if (!blocking->is_complete()) {
1065 blocking->push_wait_list(curr);
1074 * Stores the ModelAction for the current thread action. Call this
1075 * immediately before switching from user- to system-context to pass
1076 * data between them.
1077 * @param act The ModelAction created by the user-thread action
1079 void ModelChecker::set_current_action(ModelAction *act) {
1080 priv->current_action = act;
1084 * This is the heart of the model checker routine. It performs model-checking
1085 * actions corresponding to a given "current action." Among other processes, it
1086 * calculates reads-from relationships, updates synchronization clock vectors,
1087 * forms a memory_order constraints graph, and handles replay/backtrack
1088 * execution when running permutations of previously-observed executions.
1090 * @param curr The current action to process
1091 * @return The next Thread that must be executed. May be NULL if ModelChecker
1092 * makes no choice (e.g., according to replay execution, combining RMW actions,
1095 Thread * ModelChecker::check_current_action(ModelAction *curr)
1098 bool second_part_of_rmw = curr->is_rmwc() || curr->is_rmw();
1100 if (!check_action_enabled(curr)) {
1101 /* Make the execution look like we chose to run this action
1102 * much later, when a lock/join can succeed */
1103 get_current_thread()->set_pending(curr);
1104 scheduler->sleep(get_current_thread());
1105 return get_next_thread(NULL);
1108 bool newly_explored = initialize_curr_action(&curr);
1110 wake_up_sleeping_actions(curr);
1112 /* Add the action to lists before any other model-checking tasks */
1113 if (!second_part_of_rmw)
1114 add_action_to_lists(curr);
1116 /* Build may_read_from set for newly-created actions */
1117 if (newly_explored && curr->is_read())
1118 build_reads_from_past(curr);
1120 /* Initialize work_queue with the "current action" work */
1121 work_queue_t work_queue(1, CheckCurrWorkEntry(curr));
1122 while (!work_queue.empty() && !has_asserted()) {
1123 WorkQueueEntry work = work_queue.front();
1124 work_queue.pop_front();
1126 switch (work.type) {
1127 case WORK_CHECK_CURR_ACTION: {
1128 ModelAction *act = work.action;
1129 bool update = false; /* update this location's release seq's */
1130 bool update_all = false; /* update all release seq's */
1132 if (process_thread_action(curr))
1135 if (act->is_read() && process_read(act, second_part_of_rmw))
1138 if (act->is_write() && process_write(act))
1141 if (act->is_mutex_op() && process_mutex(act))
1144 if (act->is_relseq_fixup())
1145 process_relseq_fixup(curr, &work_queue);
1148 work_queue.push_back(CheckRelSeqWorkEntry(NULL));
1150 work_queue.push_back(CheckRelSeqWorkEntry(act->get_location()));
1153 case WORK_CHECK_RELEASE_SEQ:
1154 resolve_release_sequences(work.location, &work_queue);
1156 case WORK_CHECK_MO_EDGES: {
1157 /** @todo Complete verification of work_queue */
1158 ModelAction *act = work.action;
1159 bool updated = false;
1161 if (act->is_read()) {
1162 const ModelAction *rf = act->get_reads_from();
1163 if (rf != NULL && r_modification_order(act, rf))
1166 if (act->is_write()) {
1167 if (w_modification_order(act))
1170 mo_graph->commitChanges();
1173 work_queue.push_back(CheckRelSeqWorkEntry(act->get_location()));
1182 check_curr_backtracking(curr);
1183 set_backtracking(curr);
1184 return get_next_thread(curr);
1187 void ModelChecker::check_curr_backtracking(ModelAction * curr) {
1188 Node *currnode = curr->get_node();
1189 Node *parnode = currnode->get_parent();
1191 if ((!parnode->backtrack_empty() ||
1192 !currnode->misc_empty() ||
1193 !currnode->read_from_empty() ||
1194 !currnode->future_value_empty() ||
1195 !currnode->promise_empty() ||
1196 !currnode->relseq_break_empty())
1197 && (!priv->next_backtrack ||
1198 *curr > *priv->next_backtrack)) {
1199 priv->next_backtrack = curr;
1203 bool ModelChecker::promises_expired() const
1205 for (unsigned int promise_index = 0; promise_index < promises->size(); promise_index++) {
1206 Promise *promise = (*promises)[promise_index];
1207 if (promise->get_expiration()<priv->used_sequence_numbers) {
1215 * This is the strongest feasibility check available.
1216 * @return whether the current trace (partial or complete) must be a prefix of
1219 bool ModelChecker::isfeasibleprefix() const
1221 return pending_rel_seqs->size() == 0 && is_feasible_prefix_ignore_relseq();
1225 * Returns whether the current completed trace is feasible, except for pending
1226 * release sequences.
1228 bool ModelChecker::is_feasible_prefix_ignore_relseq() const
1230 if (DBG_ENABLED() && promises->size() != 0)
1231 DEBUG("Infeasible: unrevolved promises\n");
1233 return !is_infeasible() && promises->size() == 0;
1237 * Check if the current partial trace is infeasible. Does not check any
1238 * end-of-execution flags, which might rule out the execution. Thus, this is
1239 * useful only for ruling an execution as infeasible.
1240 * @return whether the current partial trace is infeasible.
1242 bool ModelChecker::is_infeasible() const
1244 if (DBG_ENABLED() && mo_graph->checkForRMWViolation())
1245 DEBUG("Infeasible: RMW violation\n");
1247 return mo_graph->checkForRMWViolation() || is_infeasible_ignoreRMW();
1251 * Check If the current partial trace is infeasible, while ignoring
1252 * infeasibility related to 2 RMW's reading from the same store. It does not
1253 * check end-of-execution feasibility.
1254 * @see ModelChecker::is_infeasible
1255 * @return whether the current partial trace is infeasible, ignoring multiple
1256 * RMWs reading from the same store.
1258 bool ModelChecker::is_infeasible_ignoreRMW() const
1260 if (DBG_ENABLED()) {
1261 if (mo_graph->checkForCycles())
1262 DEBUG("Infeasible: modification order cycles\n");
1263 if (priv->failed_promise)
1264 DEBUG("Infeasible: failed promise\n");
1265 if (priv->too_many_reads)
1266 DEBUG("Infeasible: too many reads\n");
1267 if (priv->bad_synchronization)
1268 DEBUG("Infeasible: bad synchronization ordering\n");
1269 if (promises_expired())
1270 DEBUG("Infeasible: promises expired\n");
1272 return mo_graph->checkForCycles() || priv->failed_promise ||
1273 priv->too_many_reads || priv->bad_synchronization ||
1277 /** Close out a RMWR by converting previous RMWR into a RMW or READ. */
1278 ModelAction * ModelChecker::process_rmw(ModelAction *act) {
1279 ModelAction *lastread = get_last_action(act->get_tid());
1280 lastread->process_rmw(act);
1281 if (act->is_rmw() && lastread->get_reads_from()!=NULL) {
1282 mo_graph->addRMWEdge(lastread->get_reads_from(), lastread);
1283 mo_graph->commitChanges();
1289 * Checks whether a thread has read from the same write for too many times
1290 * without seeing the effects of a later write.
1293 * 1) there must a different write that we could read from that would satisfy the modification order,
1294 * 2) we must have read from the same value in excess of maxreads times, and
1295 * 3) that other write must have been in the reads_from set for maxreads times.
1297 * If so, we decide that the execution is no longer feasible.
1299 void ModelChecker::check_recency(ModelAction *curr, const ModelAction *rf) {
1300 if (params.maxreads != 0) {
1302 if (curr->get_node()->get_read_from_size() <= 1)
1304 //Must make sure that execution is currently feasible... We could
1305 //accidentally clear by rolling back
1306 if (is_infeasible())
1308 std::vector<action_list_t> *thrd_lists = get_safe_ptr_vect_action(obj_thrd_map, curr->get_location());
1309 int tid = id_to_int(curr->get_tid());
1312 if ((int)thrd_lists->size() <= tid)
1314 action_list_t *list = &(*thrd_lists)[tid];
1316 action_list_t::reverse_iterator rit = list->rbegin();
1317 /* Skip past curr */
1318 for (; (*rit) != curr; rit++)
1320 /* go past curr now */
1323 action_list_t::reverse_iterator ritcopy = rit;
1324 //See if we have enough reads from the same value
1326 for (; count < params.maxreads; rit++,count++) {
1327 if (rit==list->rend())
1329 ModelAction *act = *rit;
1330 if (!act->is_read())
1333 if (act->get_reads_from() != rf)
1335 if (act->get_node()->get_read_from_size() <= 1)
1338 for (int i = 0; i<curr->get_node()->get_read_from_size(); i++) {
1340 const ModelAction * write = curr->get_node()->get_read_from_at(i);
1342 //Need a different write
1346 /* Test to see whether this is a feasible write to read from*/
1347 mo_graph->startChanges();
1348 r_modification_order(curr, write);
1349 bool feasiblereadfrom = !is_infeasible();
1350 mo_graph->rollbackChanges();
1352 if (!feasiblereadfrom)
1356 bool feasiblewrite = true;
1357 //new we need to see if this write works for everyone
1359 for (int loop = count; loop>0; loop--,rit++) {
1360 ModelAction *act=*rit;
1361 bool foundvalue = false;
1362 for (int j = 0; j<act->get_node()->get_read_from_size(); j++) {
1363 if (act->get_node()->get_read_from_at(j)==write) {
1369 feasiblewrite = false;
1373 if (feasiblewrite) {
1374 priv->too_many_reads = true;
1382 * Updates the mo_graph with the constraints imposed from the current
1385 * Basic idea is the following: Go through each other thread and find
1386 * the lastest action that happened before our read. Two cases:
1388 * (1) The action is a write => that write must either occur before
1389 * the write we read from or be the write we read from.
1391 * (2) The action is a read => the write that that action read from
1392 * must occur before the write we read from or be the same write.
1394 * @param curr The current action. Must be a read.
1395 * @param rf The action that curr reads from. Must be a write.
1396 * @return True if modification order edges were added; false otherwise
1398 bool ModelChecker::r_modification_order(ModelAction *curr, const ModelAction *rf)
1400 std::vector<action_list_t> *thrd_lists = get_safe_ptr_vect_action(obj_thrd_map, curr->get_location());
1403 ASSERT(curr->is_read());
1405 /* Iterate over all threads */
1406 for (i = 0; i < thrd_lists->size(); i++) {
1407 /* Iterate over actions in thread, starting from most recent */
1408 action_list_t *list = &(*thrd_lists)[i];
1409 action_list_t::reverse_iterator rit;
1410 for (rit = list->rbegin(); rit != list->rend(); rit++) {
1411 ModelAction *act = *rit;
1414 * Include at most one act per-thread that "happens
1415 * before" curr. Don't consider reflexively.
1417 if (act->happens_before(curr) && act != curr) {
1418 if (act->is_write()) {
1420 mo_graph->addEdge(act, rf);
1424 const ModelAction *prevreadfrom = act->get_reads_from();
1425 //if the previous read is unresolved, keep going...
1426 if (prevreadfrom == NULL)
1429 if (rf != prevreadfrom) {
1430 mo_graph->addEdge(prevreadfrom, rf);
1442 /** This method fixes up the modification order when we resolve a
1443 * promises. The basic problem is that actions that occur after the
1444 * read curr could not property add items to the modification order
1447 * So for each thread, we find the earliest item that happens after
1448 * the read curr. This is the item we have to fix up with additional
1449 * constraints. If that action is write, we add a MO edge between
1450 * the Action rf and that action. If the action is a read, we add a
1451 * MO edge between the Action rf, and whatever the read accessed.
1453 * @param curr is the read ModelAction that we are fixing up MO edges for.
1454 * @param rf is the write ModelAction that curr reads from.
1457 void ModelChecker::post_r_modification_order(ModelAction *curr, const ModelAction *rf)
1459 std::vector<action_list_t> *thrd_lists = get_safe_ptr_vect_action(obj_thrd_map, curr->get_location());
1461 ASSERT(curr->is_read());
1463 /* Iterate over all threads */
1464 for (i = 0; i < thrd_lists->size(); i++) {
1465 /* Iterate over actions in thread, starting from most recent */
1466 action_list_t *list = &(*thrd_lists)[i];
1467 action_list_t::reverse_iterator rit;
1468 ModelAction *lastact = NULL;
1470 /* Find last action that happens after curr that is either not curr or a rmw */
1471 for (rit = list->rbegin(); rit != list->rend(); rit++) {
1472 ModelAction *act = *rit;
1473 if (curr->happens_before(act) && (curr != act || curr->is_rmw())) {
1479 /* Include at most one act per-thread that "happens before" curr */
1480 if (lastact != NULL) {
1481 if (lastact==curr) {
1482 //Case 1: The resolved read is a RMW, and we need to make sure
1483 //that the write portion of the RMW mod order after rf
1485 mo_graph->addEdge(rf, lastact);
1486 } else if (lastact->is_read()) {
1487 //Case 2: The resolved read is a normal read and the next
1488 //operation is a read, and we need to make sure the value read
1489 //is mod ordered after rf
1491 const ModelAction *postreadfrom = lastact->get_reads_from();
1492 if (postreadfrom != NULL&&rf != postreadfrom)
1493 mo_graph->addEdge(rf, postreadfrom);
1495 //Case 3: The resolved read is a normal read and the next
1496 //operation is a write, and we need to make sure that the
1497 //write is mod ordered after rf
1499 mo_graph->addEdge(rf, lastact);
1507 * Updates the mo_graph with the constraints imposed from the current write.
1509 * Basic idea is the following: Go through each other thread and find
1510 * the lastest action that happened before our write. Two cases:
1512 * (1) The action is a write => that write must occur before
1515 * (2) The action is a read => the write that that action read from
1516 * must occur before the current write.
1518 * This method also handles two other issues:
1520 * (I) Sequential Consistency: Making sure that if the current write is
1521 * seq_cst, that it occurs after the previous seq_cst write.
1523 * (II) Sending the write back to non-synchronizing reads.
1525 * @param curr The current action. Must be a write.
1526 * @return True if modification order edges were added; false otherwise
1528 bool ModelChecker::w_modification_order(ModelAction *curr)
1530 std::vector<action_list_t> *thrd_lists = get_safe_ptr_vect_action(obj_thrd_map, curr->get_location());
1533 ASSERT(curr->is_write());
1535 if (curr->is_seqcst()) {
1536 /* We have to at least see the last sequentially consistent write,
1537 so we are initialized. */
1538 ModelAction *last_seq_cst = get_last_seq_cst_write(curr);
1539 if (last_seq_cst != NULL) {
1540 mo_graph->addEdge(last_seq_cst, curr);
1545 /* Iterate over all threads */
1546 for (i = 0; i < thrd_lists->size(); i++) {
1547 /* Iterate over actions in thread, starting from most recent */
1548 action_list_t *list = &(*thrd_lists)[i];
1549 action_list_t::reverse_iterator rit;
1550 for (rit = list->rbegin(); rit != list->rend(); rit++) {
1551 ModelAction *act = *rit;
1554 * 1) If RMW and it actually read from something, then we
1555 * already have all relevant edges, so just skip to next
1558 * 2) If RMW and it didn't read from anything, we should
1559 * whatever edge we can get to speed up convergence.
1561 * 3) If normal write, we need to look at earlier actions, so
1562 * continue processing list.
1564 if (curr->is_rmw()) {
1565 if (curr->get_reads_from()!=NULL)
1574 * Include at most one act per-thread that "happens
1577 if (act->happens_before(curr)) {
1579 * Note: if act is RMW, just add edge:
1581 * The following edge should be handled elsewhere:
1582 * readfrom(act) --mo--> act
1584 if (act->is_write())
1585 mo_graph->addEdge(act, curr);
1586 else if (act->is_read()) {
1587 //if previous read accessed a null, just keep going
1588 if (act->get_reads_from() == NULL)
1590 mo_graph->addEdge(act->get_reads_from(), curr);
1594 } else if (act->is_read() && !act->could_synchronize_with(curr) &&
1595 !act->same_thread(curr)) {
1596 /* We have an action that:
1597 (1) did not happen before us
1598 (2) is a read and we are a write
1599 (3) cannot synchronize with us
1600 (4) is in a different thread
1602 that read could potentially read from our write. Note that
1603 these checks are overly conservative at this point, we'll
1604 do more checks before actually removing the
1608 if (thin_air_constraint_may_allow(curr, act)) {
1609 if (!is_infeasible() ||
1610 (curr->is_rmw() && act->is_rmw() && curr->get_reads_from() == act->get_reads_from() && !is_infeasible_ignoreRMW())) {
1611 struct PendingFutureValue pfv = {curr,act};
1612 futurevalues->push_back(pfv);
1622 /** Arbitrary reads from the future are not allowed. Section 29.3
1623 * part 9 places some constraints. This method checks one result of constraint
1624 * constraint. Others require compiler support. */
1625 bool ModelChecker::thin_air_constraint_may_allow(const ModelAction * writer, const ModelAction *reader) {
1626 if (!writer->is_rmw())
1629 if (!reader->is_rmw())
1632 for (const ModelAction *search = writer->get_reads_from(); search != NULL; search = search->get_reads_from()) {
1633 if (search == reader)
1635 if (search->get_tid() == reader->get_tid() &&
1636 search->happens_before(reader))
1644 * Arbitrary reads from the future are not allowed. Section 29.3 part 9 places
1645 * some constraints. This method checks one the following constraint (others
1646 * require compiler support):
1648 * If X --hb-> Y --mo-> Z, then X should not read from Z.
1650 bool ModelChecker::mo_may_allow(const ModelAction *writer, const ModelAction *reader)
1652 std::vector<action_list_t> *thrd_lists = get_safe_ptr_vect_action(obj_thrd_map, reader->get_location());
1654 /* Iterate over all threads */
1655 for (i = 0; i < thrd_lists->size(); i++) {
1656 const ModelAction *write_after_read = NULL;
1658 /* Iterate over actions in thread, starting from most recent */
1659 action_list_t *list = &(*thrd_lists)[i];
1660 action_list_t::reverse_iterator rit;
1661 for (rit = list->rbegin(); rit != list->rend(); rit++) {
1662 ModelAction *act = *rit;
1664 if (!reader->happens_before(act))
1666 else if (act->is_write())
1667 write_after_read = act;
1668 else if (act->is_read() && act->get_reads_from() != NULL && act != reader) {
1669 write_after_read = act->get_reads_from();
1673 if (write_after_read && write_after_read!=writer && mo_graph->checkReachable(write_after_read, writer))
1680 * Finds the head(s) of the release sequence(s) containing a given ModelAction.
1681 * The ModelAction under consideration is expected to be taking part in
1682 * release/acquire synchronization as an object of the "reads from" relation.
1683 * Note that this can only provide release sequence support for RMW chains
1684 * which do not read from the future, as those actions cannot be traced until
1685 * their "promise" is fulfilled. Similarly, we may not even establish the
1686 * presence of a release sequence with certainty, as some modification order
1687 * constraints may be decided further in the future. Thus, this function
1688 * "returns" two pieces of data: a pass-by-reference vector of @a release_heads
1689 * and a boolean representing certainty.
1691 * @param rf The action that might be part of a release sequence. Must be a
1693 * @param release_heads A pass-by-reference style return parameter. After
1694 * execution of this function, release_heads will contain the heads of all the
1695 * relevant release sequences, if any exists with certainty
1696 * @param pending A pass-by-reference style return parameter which is only used
1697 * when returning false (i.e., uncertain). Returns most information regarding
1698 * an uncertain release sequence, including any write operations that might
1699 * break the sequence.
1700 * @return true, if the ModelChecker is certain that release_heads is complete;
1703 bool ModelChecker::release_seq_heads(const ModelAction *rf,
1704 rel_heads_list_t *release_heads,
1705 struct release_seq *pending) const
1707 /* Only check for release sequences if there are no cycles */
1708 if (mo_graph->checkForCycles())
1712 ASSERT(rf->is_write());
1714 if (rf->is_release())
1715 release_heads->push_back(rf);
1717 break; /* End of RMW chain */
1719 /** @todo Need to be smarter here... In the linux lock
1720 * example, this will run to the beginning of the program for
1722 /** @todo The way to be smarter here is to keep going until 1
1723 * thread has a release preceded by an acquire and you've seen
1726 /* acq_rel RMW is a sufficient stopping condition */
1727 if (rf->is_acquire() && rf->is_release())
1728 return true; /* complete */
1730 rf = rf->get_reads_from();
1733 /* read from future: need to settle this later */
1735 return false; /* incomplete */
1738 if (rf->is_release())
1739 return true; /* complete */
1741 /* else relaxed write; check modification order for contiguous subsequence
1742 * -> rf must be same thread as release */
1743 int tid = id_to_int(rf->get_tid());
1744 std::vector<action_list_t> *thrd_lists = get_safe_ptr_vect_action(obj_thrd_map, rf->get_location());
1745 action_list_t *list = &(*thrd_lists)[tid];
1746 action_list_t::const_reverse_iterator rit;
1748 /* Find rf in the thread list */
1749 rit = std::find(list->rbegin(), list->rend(), rf);
1750 ASSERT(rit != list->rend());
1752 /* Find the last write/release */
1753 for (; rit != list->rend(); rit++)
1754 if ((*rit)->is_release())
1756 if (rit == list->rend()) {
1757 /* No write-release in this thread */
1758 return true; /* complete */
1760 ModelAction *release = *rit;
1762 ASSERT(rf->same_thread(release));
1764 pending->writes.clear();
1766 bool certain = true;
1767 for (unsigned int i = 0; i < thrd_lists->size(); i++) {
1768 if (id_to_int(rf->get_tid()) == (int)i)
1770 list = &(*thrd_lists)[i];
1772 /* Can we ensure no future writes from this thread may break
1773 * the release seq? */
1774 bool future_ordered = false;
1776 ModelAction *last = get_last_action(int_to_id(i));
1777 Thread *th = get_thread(int_to_id(i));
1778 if ((last && rf->happens_before(last)) ||
1781 future_ordered = true;
1783 ASSERT(!th->is_model_thread() || future_ordered);
1785 for (rit = list->rbegin(); rit != list->rend(); rit++) {
1786 const ModelAction *act = *rit;
1787 /* Reach synchronization -> this thread is complete */
1788 if (act->happens_before(release))
1790 if (rf->happens_before(act)) {
1791 future_ordered = true;
1795 /* Only non-RMW writes can break release sequences */
1796 if (!act->is_write() || act->is_rmw())
1799 /* Check modification order */
1800 if (mo_graph->checkReachable(rf, act)) {
1801 /* rf --mo--> act */
1802 future_ordered = true;
1805 if (mo_graph->checkReachable(act, release))
1806 /* act --mo--> release */
1808 if (mo_graph->checkReachable(release, act) &&
1809 mo_graph->checkReachable(act, rf)) {
1810 /* release --mo-> act --mo--> rf */
1811 return true; /* complete */
1813 /* act may break release sequence */
1814 pending->writes.push_back(act);
1817 if (!future_ordered)
1818 certain = false; /* This thread is uncertain */
1822 release_heads->push_back(release);
1823 pending->writes.clear();
1825 pending->release = release;
1832 * A public interface for getting the release sequence head(s) with which a
1833 * given ModelAction must synchronize. This function only returns a non-empty
1834 * result when it can locate a release sequence head with certainty. Otherwise,
1835 * it may mark the internal state of the ModelChecker so that it will handle
1836 * the release sequence at a later time, causing @a act to update its
1837 * synchronization at some later point in execution.
1838 * @param act The 'acquire' action that may read from a release sequence
1839 * @param release_heads A pass-by-reference return parameter. Will be filled
1840 * with the head(s) of the release sequence(s), if they exists with certainty.
1841 * @see ModelChecker::release_seq_heads
1843 void ModelChecker::get_release_seq_heads(ModelAction *act, rel_heads_list_t *release_heads)
1845 const ModelAction *rf = act->get_reads_from();
1846 struct release_seq *sequence = (struct release_seq *)snapshot_calloc(1, sizeof(struct release_seq));
1847 sequence->acquire = act;
1849 if (!release_seq_heads(rf, release_heads, sequence)) {
1850 /* add act to 'lazy checking' list */
1851 pending_rel_seqs->push_back(sequence);
1853 snapshot_free(sequence);
1858 * Attempt to resolve all stashed operations that might synchronize with a
1859 * release sequence for a given location. This implements the "lazy" portion of
1860 * determining whether or not a release sequence was contiguous, since not all
1861 * modification order information is present at the time an action occurs.
1863 * @param location The location/object that should be checked for release
1864 * sequence resolutions. A NULL value means to check all locations.
1865 * @param work_queue The work queue to which to add work items as they are
1867 * @return True if any updates occurred (new synchronization, new mo_graph
1870 bool ModelChecker::resolve_release_sequences(void *location, work_queue_t *work_queue)
1872 bool updated = false;
1873 std::vector< struct release_seq *, SnapshotAlloc<struct release_seq *> >::iterator it = pending_rel_seqs->begin();
1874 while (it != pending_rel_seqs->end()) {
1875 struct release_seq *pending = *it;
1876 ModelAction *act = pending->acquire;
1878 /* Only resolve sequences on the given location, if provided */
1879 if (location && act->get_location() != location) {
1884 const ModelAction *rf = act->get_reads_from();
1885 rel_heads_list_t release_heads;
1887 complete = release_seq_heads(rf, &release_heads, pending);
1888 for (unsigned int i = 0; i < release_heads.size(); i++) {
1889 if (!act->has_synchronized_with(release_heads[i])) {
1890 if (act->synchronize_with(release_heads[i]))
1893 set_bad_synchronization();
1898 /* Re-check all pending release sequences */
1899 work_queue->push_back(CheckRelSeqWorkEntry(NULL));
1900 /* Re-check act for mo_graph edges */
1901 work_queue->push_back(MOEdgeWorkEntry(act));
1903 /* propagate synchronization to later actions */
1904 action_list_t::reverse_iterator rit = action_trace->rbegin();
1905 for (; (*rit) != act; rit++) {
1906 ModelAction *propagate = *rit;
1907 if (act->happens_before(propagate)) {
1908 propagate->synchronize_with(act);
1909 /* Re-check 'propagate' for mo_graph edges */
1910 work_queue->push_back(MOEdgeWorkEntry(propagate));
1915 it = pending_rel_seqs->erase(it);
1916 snapshot_free(pending);
1922 // If we resolved promises or data races, see if we have realized a data race.
1929 * Performs various bookkeeping operations for the current ModelAction. For
1930 * instance, adds action to the per-object, per-thread action vector and to the
1931 * action trace list of all thread actions.
1933 * @param act is the ModelAction to add.
1935 void ModelChecker::add_action_to_lists(ModelAction *act)
1937 int tid = id_to_int(act->get_tid());
1938 action_trace->push_back(act);
1940 get_safe_ptr_action(obj_map, act->get_location())->push_back(act);
1942 std::vector<action_list_t> *vec = get_safe_ptr_vect_action(obj_thrd_map, act->get_location());
1943 if (tid >= (int)vec->size())
1944 vec->resize(priv->next_thread_id);
1945 (*vec)[tid].push_back(act);
1947 if ((int)thrd_last_action->size() <= tid)
1948 thrd_last_action->resize(get_num_threads());
1949 (*thrd_last_action)[tid] = act;
1951 if (act->is_wait()) {
1952 void *mutex_loc=(void *) act->get_value();
1953 get_safe_ptr_action(obj_map, mutex_loc)->push_back(act);
1955 std::vector<action_list_t> *vec = get_safe_ptr_vect_action(obj_thrd_map, mutex_loc);
1956 if (tid >= (int)vec->size())
1957 vec->resize(priv->next_thread_id);
1958 (*vec)[tid].push_back(act);
1960 if ((int)thrd_last_action->size() <= tid)
1961 thrd_last_action->resize(get_num_threads());
1962 (*thrd_last_action)[tid] = act;
1967 * @brief Get the last action performed by a particular Thread
1968 * @param tid The thread ID of the Thread in question
1969 * @return The last action in the thread
1971 ModelAction * ModelChecker::get_last_action(thread_id_t tid) const
1973 int threadid = id_to_int(tid);
1974 if (threadid < (int)thrd_last_action->size())
1975 return (*thrd_last_action)[id_to_int(tid)];
1981 * Gets the last memory_order_seq_cst write (in the total global sequence)
1982 * performed on a particular object (i.e., memory location), not including the
1984 * @param curr The current ModelAction; also denotes the object location to
1986 * @return The last seq_cst write
1988 ModelAction * ModelChecker::get_last_seq_cst_write(ModelAction *curr) const
1990 void *location = curr->get_location();
1991 action_list_t *list = get_safe_ptr_action(obj_map, location);
1992 /* Find: max({i in dom(S) | seq_cst(t_i) && isWrite(t_i) && samevar(t_i, t)}) */
1993 action_list_t::reverse_iterator rit;
1994 for (rit = list->rbegin(); rit != list->rend(); rit++)
1995 if ((*rit)->is_write() && (*rit)->is_seqcst() && (*rit) != curr)
2001 * Gets the last memory_order_seq_cst fence (in the total global sequence)
2002 * performed in a particular thread, prior to a particular fence.
2003 * @param tid The ID of the thread to check
2004 * @param before_fence The fence from which to begin the search; if NULL, then
2005 * search for the most recent fence in the thread.
2006 * @return The last prior seq_cst fence in the thread, if exists; otherwise, NULL
2008 ModelAction * ModelChecker::get_last_seq_cst_fence(thread_id_t tid, const ModelAction *before_fence) const
2010 /* All fences should have NULL location */
2011 action_list_t *list = get_safe_ptr_action(obj_map, NULL);
2012 action_list_t::reverse_iterator rit = list->rbegin();
2015 for (; rit != list->rend(); rit++)
2016 if (*rit == before_fence)
2019 ASSERT(*rit == before_fence);
2023 for (; rit != list->rend(); rit++)
2024 if ((*rit)->is_fence() && (tid == (*rit)->get_tid()) && (*rit)->is_seqcst())
2030 * Gets the last unlock operation performed on a particular mutex (i.e., memory
2031 * location). This function identifies the mutex according to the current
2032 * action, which is presumed to perform on the same mutex.
2033 * @param curr The current ModelAction; also denotes the object location to
2035 * @return The last unlock operation
2037 ModelAction * ModelChecker::get_last_unlock(ModelAction *curr) const
2039 void *location = curr->get_location();
2040 action_list_t *list = get_safe_ptr_action(obj_map, location);
2041 /* Find: max({i in dom(S) | isUnlock(t_i) && samevar(t_i, t)}) */
2042 action_list_t::reverse_iterator rit;
2043 for (rit = list->rbegin(); rit != list->rend(); rit++)
2044 if ((*rit)->is_unlock() || (*rit)->is_wait())
2049 ModelAction * ModelChecker::get_parent_action(thread_id_t tid) const
2051 ModelAction *parent = get_last_action(tid);
2053 parent = get_thread(tid)->get_creation();
2058 * Returns the clock vector for a given thread.
2059 * @param tid The thread whose clock vector we want
2060 * @return Desired clock vector
2062 ClockVector * ModelChecker::get_cv(thread_id_t tid) const
2064 return get_parent_action(tid)->get_cv();
2068 * Resolve a set of Promises with a current write. The set is provided in the
2069 * Node corresponding to @a write.
2070 * @param write The ModelAction that is fulfilling Promises
2071 * @return True if promises were resolved; false otherwise
2073 bool ModelChecker::resolve_promises(ModelAction *write)
2075 bool resolved = false;
2076 std::vector< thread_id_t, ModelAlloc<thread_id_t> > threads_to_check;
2078 for (unsigned int i = 0, promise_index = 0; promise_index < promises->size(); i++) {
2079 Promise *promise = (*promises)[promise_index];
2080 if (write->get_node()->get_promise(i)) {
2081 ModelAction *read = promise->get_action();
2082 if (read->is_rmw()) {
2083 mo_graph->addRMWEdge(write, read);
2085 read->read_from(write);
2086 //First fix up the modification order for actions that happened
2088 r_modification_order(read, write);
2089 //Next fix up the modification order for actions that happened
2091 post_r_modification_order(read, write);
2092 //Make sure the promise's value matches the write's value
2093 ASSERT(promise->get_value() == write->get_value());
2096 promises->erase(promises->begin() + promise_index);
2097 threads_to_check.push_back(read->get_tid());
2104 //Check whether reading these writes has made threads unable to
2107 for(unsigned int i=0;i<threads_to_check.size();i++)
2108 mo_check_promises(threads_to_check[i], write);
2114 * Compute the set of promises that could potentially be satisfied by this
2115 * action. Note that the set computation actually appears in the Node, not in
2117 * @param curr The ModelAction that may satisfy promises
2119 void ModelChecker::compute_promises(ModelAction *curr)
2121 for (unsigned int i = 0; i < promises->size(); i++) {
2122 Promise *promise = (*promises)[i];
2123 const ModelAction *act = promise->get_action();
2124 if (!act->happens_before(curr) &&
2126 !act->could_synchronize_with(curr) &&
2127 !act->same_thread(curr) &&
2128 act->get_location() == curr->get_location() &&
2129 promise->get_value() == curr->get_value()) {
2130 curr->get_node()->set_promise(i, act->is_rmw());
2135 /** Checks promises in response to change in ClockVector Threads. */
2136 void ModelChecker::check_promises(thread_id_t tid, ClockVector *old_cv, ClockVector *merge_cv)
2138 for (unsigned int i = 0; i < promises->size(); i++) {
2139 Promise *promise = (*promises)[i];
2140 const ModelAction *act = promise->get_action();
2141 if ((old_cv == NULL || !old_cv->synchronized_since(act)) &&
2142 merge_cv->synchronized_since(act)) {
2143 if (promise->increment_threads(tid)) {
2144 //Promise has failed
2145 priv->failed_promise = true;
2152 void ModelChecker::check_promises_thread_disabled() {
2153 for (unsigned int i = 0; i < promises->size(); i++) {
2154 Promise *promise = (*promises)[i];
2155 if (promise->check_promise()) {
2156 priv->failed_promise = true;
2162 /** Checks promises in response to addition to modification order for threads.
2164 * pthread is the thread that performed the read that created the promise
2166 * pread is the read that created the promise
2168 * pwrite is either the first write to same location as pread by
2169 * pthread that is sequenced after pread or the value read by the
2170 * first read to the same lcoation as pread by pthread that is
2171 * sequenced after pread..
2173 * 1. If tid=pthread, then we check what other threads are reachable
2174 * through the mode order starting with pwrite. Those threads cannot
2175 * perform a write that will resolve the promise due to modification
2176 * order constraints.
2178 * 2. If the tid is not pthread, we check whether pwrite can reach the
2179 * action write through the modification order. If so, that thread
2180 * cannot perform a future write that will resolve the promise due to
2181 * modificatin order constraints.
2183 * @parem tid The thread that either read from the model action
2184 * write, or actually did the model action write.
2186 * @parem write The ModelAction representing the relevant write.
2189 void ModelChecker::mo_check_promises(thread_id_t tid, const ModelAction *write) {
2190 void * location = write->get_location();
2191 for (unsigned int i = 0; i < promises->size(); i++) {
2192 Promise *promise = (*promises)[i];
2193 const ModelAction *act = promise->get_action();
2195 //Is this promise on the same location?
2196 if ( act->get_location() != location )
2199 //same thread as the promise
2200 if ( act->get_tid()==tid ) {
2202 //do we have a pwrite for the promise, if not, set it
2203 if (promise->get_write() == NULL ) {
2204 promise->set_write(write);
2205 //The pwrite cannot happen before the promise
2206 if (write->happens_before(act) && (write != act)) {
2207 priv->failed_promise = true;
2211 if (mo_graph->checkPromise(write, promise)) {
2212 priv->failed_promise = true;
2217 //Don't do any lookups twice for the same thread
2218 if (promise->has_sync_thread(tid))
2221 if (promise->get_write()&&mo_graph->checkReachable(promise->get_write(), write)) {
2222 if (promise->increment_threads(tid)) {
2223 priv->failed_promise = true;
2231 * Compute the set of writes that may break the current pending release
2232 * sequence. This information is extracted from previou release sequence
2235 * @param curr The current ModelAction. Must be a release sequence fixup
2238 void ModelChecker::compute_relseq_breakwrites(ModelAction *curr)
2240 if (pending_rel_seqs->empty())
2243 struct release_seq *pending = pending_rel_seqs->back();
2244 for (unsigned int i = 0; i < pending->writes.size(); i++) {
2245 const ModelAction *write = pending->writes[i];
2246 curr->get_node()->add_relseq_break(write);
2249 /* NULL means don't break the sequence; just synchronize */
2250 curr->get_node()->add_relseq_break(NULL);
2254 * Build up an initial set of all past writes that this 'read' action may read
2255 * from. This set is determined by the clock vector's "happens before"
2257 * @param curr is the current ModelAction that we are exploring; it must be a
2260 void ModelChecker::build_reads_from_past(ModelAction *curr)
2262 std::vector<action_list_t> *thrd_lists = get_safe_ptr_vect_action(obj_thrd_map, curr->get_location());
2264 ASSERT(curr->is_read());
2266 ModelAction *last_sc_write = NULL;
2268 /* Track whether this object has been initialized */
2269 bool initialized = false;
2271 if (curr->is_seqcst()) {
2272 last_sc_write = get_last_seq_cst_write(curr);
2273 /* We have to at least see the last sequentially consistent write,
2274 so we are initialized. */
2275 if (last_sc_write != NULL)
2279 /* Iterate over all threads */
2280 for (i = 0; i < thrd_lists->size(); i++) {
2281 /* Iterate over actions in thread, starting from most recent */
2282 action_list_t *list = &(*thrd_lists)[i];
2283 action_list_t::reverse_iterator rit;
2284 for (rit = list->rbegin(); rit != list->rend(); rit++) {
2285 ModelAction *act = *rit;
2287 /* Only consider 'write' actions */
2288 if (!act->is_write() || act == curr)
2291 /* Don't consider more than one seq_cst write if we are a seq_cst read. */
2292 if (!curr->is_seqcst() || (!act->is_seqcst() && (last_sc_write == NULL || !act->happens_before(last_sc_write))) || act == last_sc_write) {
2293 if (!curr->get_sleep_flag() || curr->is_seqcst() || sleep_can_read_from(curr, act)) {
2294 DEBUG("Adding action to may_read_from:\n");
2295 if (DBG_ENABLED()) {
2299 curr->get_node()->add_read_from(act);
2303 /* Include at most one act per-thread that "happens before" curr */
2304 if (act->happens_before(curr)) {
2312 assert_bug("May read from uninitialized atomic");
2314 if (DBG_ENABLED() || !initialized) {
2315 model_print("Reached read action:\n");
2317 model_print("Printing may_read_from\n");
2318 curr->get_node()->print_may_read_from();
2319 model_print("End printing may_read_from\n");
2323 bool ModelChecker::sleep_can_read_from(ModelAction * curr, const ModelAction *write) {
2325 Node *prevnode=write->get_node()->get_parent();
2327 bool thread_sleep=prevnode->enabled_status(curr->get_tid())==THREAD_SLEEP_SET;
2328 if (write->is_release()&&thread_sleep)
2330 if (!write->is_rmw()) {
2333 if (write->get_reads_from()==NULL)
2335 write=write->get_reads_from();
2339 static void print_list(action_list_t *list, int exec_num = -1)
2341 action_list_t::iterator it;
2343 model_print("---------------------------------------------------------------------\n");
2345 model_print("Execution %d:\n", exec_num);
2347 unsigned int hash=0;
2349 for (it = list->begin(); it != list->end(); it++) {
2351 hash=hash^(hash<<3)^((*it)->hash());
2353 model_print("HASH %u\n", hash);
2354 model_print("---------------------------------------------------------------------\n");
2357 #if SUPPORT_MOD_ORDER_DUMP
2358 void ModelChecker::dumpGraph(char *filename) {
2360 sprintf(buffer, "%s.dot",filename);
2361 FILE *file=fopen(buffer, "w");
2362 fprintf(file, "digraph %s {\n",filename);
2363 mo_graph->dumpNodes(file);
2364 ModelAction ** thread_array=(ModelAction **)model_calloc(1, sizeof(ModelAction *)*get_num_threads());
2366 for (action_list_t::iterator it = action_trace->begin(); it != action_trace->end(); it++) {
2367 ModelAction *action=*it;
2368 if (action->is_read()) {
2369 fprintf(file, "N%u [label=\"%u, T%u\"];\n", action->get_seq_number(),action->get_seq_number(), action->get_tid());
2370 if (action->get_reads_from()!=NULL)
2371 fprintf(file, "N%u -> N%u[label=\"rf\", color=red];\n", action->get_seq_number(), action->get_reads_from()->get_seq_number());
2373 if (thread_array[action->get_tid()] != NULL) {
2374 fprintf(file, "N%u -> N%u[label=\"sb\", color=blue];\n", thread_array[action->get_tid()]->get_seq_number(), action->get_seq_number());
2377 thread_array[action->get_tid()]=action;
2379 fprintf(file,"}\n");
2380 model_free(thread_array);
2385 /** @brief Prints an execution trace summary. */
2386 void ModelChecker::print_summary() const
2388 #if SUPPORT_MOD_ORDER_DUMP
2390 char buffername[100];
2391 sprintf(buffername, "exec%04u", stats.num_total);
2392 mo_graph->dumpGraphToFile(buffername);
2393 sprintf(buffername, "graph%04u", stats.num_total);
2394 dumpGraph(buffername);
2397 if (!isfeasibleprefix())
2398 model_print("INFEASIBLE EXECUTION!\n");
2399 print_list(action_trace, stats.num_total);
2404 * Add a Thread to the system for the first time. Should only be called once
2406 * @param t The Thread to add
2408 void ModelChecker::add_thread(Thread *t)
2410 thread_map->put(id_to_int(t->get_id()), t);
2411 scheduler->add_thread(t);
2415 * Removes a thread from the scheduler.
2416 * @param the thread to remove.
2418 void ModelChecker::remove_thread(Thread *t)
2420 scheduler->remove_thread(t);
2424 * @brief Get a Thread reference by its ID
2425 * @param tid The Thread's ID
2426 * @return A Thread reference
2428 Thread * ModelChecker::get_thread(thread_id_t tid) const
2430 return thread_map->get(id_to_int(tid));
2434 * @brief Get a reference to the Thread in which a ModelAction was executed
2435 * @param act The ModelAction
2436 * @return A Thread reference
2438 Thread * ModelChecker::get_thread(ModelAction *act) const
2440 return get_thread(act->get_tid());
2444 * @brief Check if a Thread is currently enabled
2445 * @param t The Thread to check
2446 * @return True if the Thread is currently enabled
2448 bool ModelChecker::is_enabled(Thread *t) const
2450 return scheduler->is_enabled(t);
2454 * @brief Check if a Thread is currently enabled
2455 * @param tid The ID of the Thread to check
2456 * @return True if the Thread is currently enabled
2458 bool ModelChecker::is_enabled(thread_id_t tid) const
2460 return scheduler->is_enabled(tid);
2464 * Switch from a user-context to the "master thread" context (a.k.a. system
2465 * context). This switch is made with the intention of exploring a particular
2466 * model-checking action (described by a ModelAction object). Must be called
2467 * from a user-thread context.
2469 * @param act The current action that will be explored. May be NULL only if
2470 * trace is exiting via an assertion (see ModelChecker::set_assert and
2471 * ModelChecker::has_asserted).
2472 * @return Return status from the 'swap' call (i.e., success/fail, 0/-1)
2474 int ModelChecker::switch_to_master(ModelAction *act)
2477 Thread *old = thread_current();
2478 set_current_action(act);
2479 old->set_state(THREAD_READY);
2480 return Thread::swap(old, &system_context);
2484 * Takes the next step in the execution, if possible.
2485 * @return Returns true (success) if a step was taken and false otherwise.
2487 bool ModelChecker::take_step() {
2491 Thread *curr = priv->current_action ? get_thread(priv->current_action) : NULL;
2493 if (curr->get_state() == THREAD_READY) {
2494 ASSERT(priv->current_action);
2496 priv->nextThread = check_current_action(priv->current_action);
2497 priv->current_action = NULL;
2499 if (curr->is_blocked() || curr->is_complete())
2500 scheduler->remove_thread(curr);
2505 Thread *next = scheduler->next_thread(priv->nextThread);
2507 /* Infeasible -> don't take any more steps */
2508 if (is_infeasible())
2510 else if (isfeasibleprefix() && have_bug_reports()) {
2515 if (params.bound != 0) {
2516 if (priv->used_sequence_numbers > params.bound) {
2521 DEBUG("(%d, %d)\n", curr ? id_to_int(curr->get_id()) : -1,
2522 next ? id_to_int(next->get_id()) : -1);
2525 * Launch end-of-execution release sequence fixups only when there are:
2527 * (1) no more user threads to run (or when execution replay chooses
2528 * the 'model_thread')
2529 * (2) pending release sequences
2530 * (3) pending assertions (i.e., data races)
2531 * (4) no pending promises
2533 if (!pending_rel_seqs->empty() && (!next || next->is_model_thread()) &&
2534 is_feasible_prefix_ignore_relseq() && !unrealizedraces.empty()) {
2535 model_print("*** WARNING: release sequence fixup action (%zu pending release seuqences) ***\n",
2536 pending_rel_seqs->size());
2537 ModelAction *fixup = new ModelAction(MODEL_FIXUP_RELSEQ,
2538 std::memory_order_seq_cst, NULL, VALUE_NONE,
2540 set_current_action(fixup);
2544 /* next == NULL -> don't take any more steps */
2548 next->set_state(THREAD_RUNNING);
2550 if (next->get_pending() != NULL) {
2551 /* restart a pending action */
2552 set_current_action(next->get_pending());
2553 next->set_pending(NULL);
2554 next->set_state(THREAD_READY);
2558 /* Return false only if swap fails with an error */
2559 return (Thread::swap(&system_context, next) == 0);
2562 /** Wrapper to run the user's main function, with appropriate arguments */
2563 void user_main_wrapper(void *)
2565 user_main(model->params.argc, model->params.argv);
2568 /** @brief Run ModelChecker for the user program */
2569 void ModelChecker::run()
2574 /* Start user program */
2575 add_thread(new Thread(&user_thread, &user_main_wrapper, NULL));
2577 /* Wait for all threads to complete */
2578 while (take_step());
2579 } while (next_execution());