11 #include "clockvector.h"
12 #include "cyclegraph.h"
14 #include "threads-model.h"
15 #include "bugmessage.h"
18 #include "newfuzzer.h"
20 #define INITIAL_THREAD_ID 0
23 * Structure for holding small ModelChecker members that should be snapshotted
25 struct model_snapshot_members {
26 model_snapshot_members() :
27 /* First thread created will have id INITIAL_THREAD_ID */
28 next_thread_id(INITIAL_THREAD_ID),
29 used_sequence_numbers(0),
34 ~model_snapshot_members() {
35 for (unsigned int i = 0;i < bugs.size();i++)
40 unsigned int next_thread_id;
41 modelclock_t used_sequence_numbers;
42 SnapVector<bug_message *> bugs;
43 /** @brief Incorrectly-ordered synchronization was made */
49 /** @brief Constructor */
50 ModelExecution::ModelExecution(ModelChecker *m, Scheduler *scheduler) :
55 thread_map(2), /* We'll always need at least 2 threads */
59 condvar_waiters_map(),
63 thrd_last_fence_release(),
64 priv(new struct model_snapshot_members ()),
65 mo_graph(new CycleGraph()),
66 fuzzer(new NewFuzzer()),
68 thrd_func_act_lists(),
71 /* Initialize a model-checker thread, for special ModelActions */
72 model_thread = new Thread(get_next_id());
73 add_thread(model_thread);
74 fuzzer->register_engine(m->get_history(), this);
75 scheduler->register_engine(this);
78 /** @brief Destructor */
79 ModelExecution::~ModelExecution()
81 for (unsigned int i = 0;i < get_num_threads();i++)
82 delete get_thread(int_to_id(i));
88 int ModelExecution::get_execution_number() const
90 return model->get_execution_number();
93 static action_list_t * get_safe_ptr_action(HashTable<const void *, action_list_t *, uintptr_t, 2> * hash, void * ptr)
95 action_list_t *tmp = hash->get(ptr);
97 tmp = new action_list_t();
103 static SnapVector<action_list_t> * get_safe_ptr_vect_action(HashTable<const void *, SnapVector<action_list_t> *, uintptr_t, 2> * hash, void * ptr)
105 SnapVector<action_list_t> *tmp = hash->get(ptr);
107 tmp = new SnapVector<action_list_t>();
113 /** @return a thread ID for a new Thread */
114 thread_id_t ModelExecution::get_next_id()
116 return priv->next_thread_id++;
119 /** @return the number of user threads created during this execution */
120 unsigned int ModelExecution::get_num_threads() const
122 return priv->next_thread_id;
125 /** @return a sequence number for a new ModelAction */
126 modelclock_t ModelExecution::get_next_seq_num()
128 return ++priv->used_sequence_numbers;
131 /** Restore the last used sequence number when actions of a thread are postponed by Fuzzer */
132 void ModelExecution::restore_last_seq_num()
134 priv->used_sequence_numbers--;
138 * @brief Should the current action wake up a given thread?
140 * @param curr The current action
141 * @param thread The thread that we might wake up
142 * @return True, if we should wake up the sleeping thread; false otherwise
144 bool ModelExecution::should_wake_up(const ModelAction *curr, const Thread *thread) const
146 const ModelAction *asleep = thread->get_pending();
147 /* Don't allow partial RMW to wake anyone up */
150 /* Synchronizing actions may have been backtracked */
151 if (asleep->could_synchronize_with(curr))
153 /* All acquire/release fences and fence-acquire/store-release */
154 if (asleep->is_fence() && asleep->is_acquire() && curr->is_release())
156 /* Fence-release + store can awake load-acquire on the same location */
157 if (asleep->is_read() && asleep->is_acquire() && curr->same_var(asleep) && curr->is_write()) {
158 ModelAction *fence_release = get_last_fence_release(curr->get_tid());
159 if (fence_release && *(get_last_action(thread->get_id())) < *fence_release)
162 /* The sleep is literally sleeping */
163 if (asleep->is_sleep()) {
164 if (fuzzer->shouldWake(asleep))
171 void ModelExecution::wake_up_sleeping_actions(ModelAction *curr)
173 for (unsigned int i = 0;i < get_num_threads();i++) {
174 Thread *thr = get_thread(int_to_id(i));
175 if (scheduler->is_sleep_set(thr)) {
176 if (should_wake_up(curr, thr)) {
177 /* Remove this thread from sleep set */
178 scheduler->remove_sleep(thr);
179 if (thr->get_pending()->is_sleep())
180 thr->set_wakeup_state(true);
186 void ModelExecution::assert_bug(const char *msg)
188 priv->bugs.push_back(new bug_message(msg));
192 /** @return True, if any bugs have been reported for this execution */
193 bool ModelExecution::have_bug_reports() const
195 return priv->bugs.size() != 0;
198 SnapVector<bug_message *> * ModelExecution::get_bugs() const
204 * Check whether the current trace has triggered an assertion which should halt
207 * @return True, if the execution should be aborted; false otherwise
209 bool ModelExecution::has_asserted() const
211 return priv->asserted;
215 * Trigger a trace assertion which should cause this execution to be halted.
216 * This can be due to a detected bug or due to an infeasibility that should
219 void ModelExecution::set_assert()
221 priv->asserted = true;
225 * Check if we are in a deadlock. Should only be called at the end of an
226 * execution, although it should not give false positives in the middle of an
227 * execution (there should be some ENABLED thread).
229 * @return True if program is in a deadlock; false otherwise
231 bool ModelExecution::is_deadlocked() const
233 bool blocking_threads = false;
234 for (unsigned int i = 0;i < get_num_threads();i++) {
235 thread_id_t tid = int_to_id(i);
238 Thread *t = get_thread(tid);
239 if (!t->is_model_thread() && t->get_pending())
240 blocking_threads = true;
242 return blocking_threads;
246 * Check if this is a complete execution. That is, have all thread completed
247 * execution (rather than exiting because sleep sets have forced a redundant
250 * @return True if the execution is complete.
252 bool ModelExecution::is_complete_execution() const
254 for (unsigned int i = 0;i < get_num_threads();i++)
255 if (is_enabled(int_to_id(i)))
260 ModelAction * ModelExecution::convertNonAtomicStore(void * location) {
261 uint64_t value = *((const uint64_t *) location);
262 modelclock_t storeclock;
263 thread_id_t storethread;
264 getStoreThreadAndClock(location, &storethread, &storeclock);
265 setAtomicStoreFlag(location);
266 ModelAction * act = new ModelAction(NONATOMIC_WRITE, memory_order_relaxed, location, value, get_thread(storethread));
267 act->set_seq_number(storeclock);
268 add_normal_write_to_lists(act);
269 add_write_to_lists(act);
270 w_modification_order(act);
271 // model->get_history()->process_action(act, act->get_tid());
276 * Processes a read model action.
277 * @param curr is the read model action to process.
278 * @param rf_set is the set of model actions we can possibly read from
279 * @return True if processing this read updates the mo_graph.
281 bool ModelExecution::process_read(ModelAction *curr, SnapVector<ModelAction *> * rf_set)
283 SnapVector<const ModelAction *> * priorset = new SnapVector<const ModelAction *>();
284 bool hasnonatomicstore = hasNonAtomicStore(curr->get_location());
285 if (hasnonatomicstore) {
286 ModelAction * nonatomicstore = convertNonAtomicStore(curr->get_location());
287 rf_set->push_back(nonatomicstore);
290 // Remove writes that violate read modification order
292 for (uint i = 0; i < rf_set->size(); i++) {
293 ModelAction * rf = (*rf_set)[i];
294 if (!r_modification_order(curr, rf, NULL, NULL, true)) {
295 (*rf_set)[i] = rf_set->back();
301 int index = fuzzer->selectWrite(curr, rf_set);
302 if (index == -1)// no feasible write exists
305 ModelAction *rf = (*rf_set)[index];
308 bool canprune = false;
309 if (r_modification_order(curr, rf, priorset, &canprune)) {
310 for(unsigned int i=0;i<priorset->size();i++) {
311 mo_graph->addEdge((*priorset)[i], rf);
314 get_thread(curr)->set_return_value(curr->get_return_value());
316 if (canprune && curr->get_type() == ATOMIC_READ) {
317 int tid = id_to_int(curr->get_tid());
318 (*obj_thrd_map.get(curr->get_location()))[tid].pop_back();
323 (*rf_set)[index] = rf_set->back();
329 * Processes a lock, trylock, or unlock model action. @param curr is
330 * the read model action to process.
332 * The try lock operation checks whether the lock is taken. If not,
333 * it falls to the normal lock operation case. If so, it returns
336 * The lock operation has already been checked that it is enabled, so
337 * it just grabs the lock and synchronizes with the previous unlock.
339 * The unlock operation has to re-enable all of the threads that are
340 * waiting on the lock.
342 * @return True if synchronization was updated; false otherwise
344 bool ModelExecution::process_mutex(ModelAction *curr)
346 cdsc::mutex *mutex = curr->get_mutex();
347 struct cdsc::mutex_state *state = NULL;
350 state = mutex->get_state();
352 switch (curr->get_type()) {
353 case ATOMIC_TRYLOCK: {
354 bool success = !state->locked;
355 curr->set_try_lock(success);
357 get_thread(curr)->set_return_value(0);
360 get_thread(curr)->set_return_value(1);
362 //otherwise fall into the lock case
364 //TODO: FIND SOME BETTER WAY TO CHECK LOCK INITIALIZED OR NOT
365 //if (curr->get_cv()->getClock(state->alloc_tid) <= state->alloc_clock)
366 // assert_bug("Lock access before initialization");
367 state->locked = get_thread(curr);
368 ModelAction *unlock = get_last_unlock(curr);
369 //synchronize with the previous unlock statement
370 if (unlock != NULL) {
371 synchronize(unlock, curr);
377 /* wake up the other threads */
378 for (unsigned int i = 0;i < get_num_threads();i++) {
379 Thread *t = get_thread(int_to_id(i));
380 Thread *curr_thrd = get_thread(curr);
381 if (t->waiting_on() == curr_thrd && t->get_pending()->is_lock())
385 /* unlock the lock - after checking who was waiting on it */
386 state->locked = NULL;
388 if (fuzzer->shouldWait(curr)) {
389 /* disable this thread */
390 get_safe_ptr_action(&condvar_waiters_map, curr->get_location())->push_back(curr);
391 scheduler->sleep(get_thread(curr));
396 case ATOMIC_TIMEDWAIT:
397 case ATOMIC_UNLOCK: {
398 //TODO: FIX WAIT SITUATION...WAITS CAN SPURIOUSLY FAIL...TIMED WAITS SHOULD PROBABLY JUST BE THE SAME AS NORMAL WAITS...THINK ABOUT PROBABILITIES THOUGH....AS IN TIMED WAIT MUST FAIL TO GUARANTEE PROGRESS...NORMAL WAIT MAY FAIL...SO NEED NORMAL WAIT TO WORK CORRECTLY IN THE CASE IT SPURIOUSLY FAILS AND IN THE CASE IT DOESN'T... TIMED WAITS MUST EVENMTUALLY RELEASE...
400 /* wake up the other threads */
401 for (unsigned int i = 0;i < get_num_threads();i++) {
402 Thread *t = get_thread(int_to_id(i));
403 Thread *curr_thrd = get_thread(curr);
404 if (t->waiting_on() == curr_thrd && t->get_pending()->is_lock())
408 /* unlock the lock - after checking who was waiting on it */
409 state->locked = NULL;
412 case ATOMIC_NOTIFY_ALL: {
413 action_list_t *waiters = get_safe_ptr_action(&condvar_waiters_map, curr->get_location());
414 //activate all the waiting threads
415 for (sllnode<ModelAction *> * rit = waiters->begin();rit != NULL;rit=rit->getNext()) {
416 scheduler->wake(get_thread(rit->getVal()));
421 case ATOMIC_NOTIFY_ONE: {
422 action_list_t *waiters = get_safe_ptr_action(&condvar_waiters_map, curr->get_location());
423 if (waiters->size() != 0) {
424 Thread * thread = fuzzer->selectNotify(waiters);
425 scheduler->wake(thread);
437 * Process a write ModelAction
438 * @param curr The ModelAction to process
439 * @return True if the mo_graph was updated or promises were resolved
441 void ModelExecution::process_write(ModelAction *curr)
443 w_modification_order(curr);
444 get_thread(curr)->set_return_value(VALUE_NONE);
448 * Process a fence ModelAction
449 * @param curr The ModelAction to process
450 * @return True if synchronization was updated
452 bool ModelExecution::process_fence(ModelAction *curr)
455 * fence-relaxed: no-op
456 * fence-release: only log the occurence (not in this function), for
457 * use in later synchronization
458 * fence-acquire (this function): search for hypothetical release
460 * fence-seq-cst: MO constraints formed in {r,w}_modification_order
462 bool updated = false;
463 if (curr->is_acquire()) {
464 action_list_t *list = &action_trace;
465 sllnode<ModelAction *> * rit;
466 /* Find X : is_read(X) && X --sb-> curr */
467 for (rit = list->end();rit != NULL;rit=rit->getPrev()) {
468 ModelAction *act = rit->getVal();
471 if (act->get_tid() != curr->get_tid())
473 /* Stop at the beginning of the thread */
474 if (act->is_thread_start())
476 /* Stop once we reach a prior fence-acquire */
477 if (act->is_fence() && act->is_acquire())
481 /* read-acquire will find its own release sequences */
482 if (act->is_acquire())
485 /* Establish hypothetical release sequences */
486 ClockVector *cv = get_hb_from_write(act->get_reads_from());
487 if (cv != NULL && curr->get_cv()->merge(cv))
495 * @brief Process the current action for thread-related activity
497 * Performs current-action processing for a THREAD_* ModelAction. Proccesses
498 * may include setting Thread status, completing THREAD_FINISH/THREAD_JOIN
499 * synchronization, etc. This function is a no-op for non-THREAD actions
500 * (e.g., ATOMIC_{READ,WRITE,RMW,LOCK}, etc.)
502 * @param curr The current action
503 * @return True if synchronization was updated or a thread completed
505 void ModelExecution::process_thread_action(ModelAction *curr)
507 switch (curr->get_type()) {
508 case THREAD_CREATE: {
509 thrd_t *thrd = (thrd_t *)curr->get_location();
510 struct thread_params *params = (struct thread_params *)curr->get_value();
511 Thread *th = new Thread(get_next_id(), thrd, params->func, params->arg, get_thread(curr));
512 curr->set_thread_operand(th);
514 th->set_creation(curr);
517 case PTHREAD_CREATE: {
518 (*(uint32_t *)curr->get_location()) = pthread_counter++;
520 struct pthread_params *params = (struct pthread_params *)curr->get_value();
521 Thread *th = new Thread(get_next_id(), NULL, params->func, params->arg, get_thread(curr));
522 curr->set_thread_operand(th);
524 th->set_creation(curr);
526 if ( pthread_map.size() < pthread_counter )
527 pthread_map.resize( pthread_counter );
528 pthread_map[ pthread_counter-1 ] = th;
533 Thread *blocking = curr->get_thread_operand();
534 ModelAction *act = get_last_action(blocking->get_id());
535 synchronize(act, curr);
539 Thread *blocking = curr->get_thread_operand();
540 ModelAction *act = get_last_action(blocking->get_id());
541 synchronize(act, curr);
542 break; // WL: to be add (modified)
545 case THREADONLY_FINISH:
546 case THREAD_FINISH: {
547 Thread *th = get_thread(curr);
548 if (curr->get_type() == THREAD_FINISH &&
549 th == model->getInitThread()) {
555 /* Wake up any joining threads */
556 for (unsigned int i = 0;i < get_num_threads();i++) {
557 Thread *waiting = get_thread(int_to_id(i));
558 if (waiting->waiting_on() == th &&
559 waiting->get_pending()->is_thread_join())
560 scheduler->wake(waiting);
569 Thread *th = get_thread(curr);
570 th->set_pending(curr);
571 scheduler->add_sleep(th);
580 * Initialize the current action by performing one or more of the following
581 * actions, as appropriate: merging RMWR and RMWC/RMW actions,
582 * manipulating backtracking sets, allocating and
583 * initializing clock vectors, and computing the promises to fulfill.
585 * @param curr The current action, as passed from the user context; may be
586 * freed/invalidated after the execution of this function, with a different
587 * action "returned" its place (pass-by-reference)
588 * @return True if curr is a newly-explored action; false otherwise
590 bool ModelExecution::initialize_curr_action(ModelAction **curr)
592 if ((*curr)->is_rmwc() || (*curr)->is_rmw()) {
593 ModelAction *newcurr = process_rmw(*curr);
599 ModelAction *newcurr = *curr;
601 newcurr->set_seq_number(get_next_seq_num());
602 /* Always compute new clock vector */
603 newcurr->create_cv(get_parent_action(newcurr->get_tid()));
605 /* Assign most recent release fence */
606 newcurr->set_last_fence_release(get_last_fence_release(newcurr->get_tid()));
608 return true; /* This was a new ModelAction */
613 * @brief Establish reads-from relation between two actions
615 * Perform basic operations involved with establishing a concrete rf relation,
616 * including setting the ModelAction data and checking for release sequences.
618 * @param act The action that is reading (must be a read)
619 * @param rf The action from which we are reading (must be a write)
621 * @return True if this read established synchronization
624 void ModelExecution::read_from(ModelAction *act, ModelAction *rf)
627 ASSERT(rf->is_write());
629 act->set_read_from(rf);
630 if (act->is_acquire()) {
631 ClockVector *cv = get_hb_from_write(rf);
634 act->get_cv()->merge(cv);
639 * @brief Synchronizes two actions
641 * When A synchronizes with B (or A --sw-> B), B inherits A's clock vector.
642 * This function performs the synchronization as well as providing other hooks
643 * for other checks along with synchronization.
645 * @param first The left-hand side of the synchronizes-with relation
646 * @param second The right-hand side of the synchronizes-with relation
647 * @return True if the synchronization was successful (i.e., was consistent
648 * with the execution order); false otherwise
650 bool ModelExecution::synchronize(const ModelAction *first, ModelAction *second)
652 if (*second < *first) {
653 ASSERT(0); //This should not happend
656 return second->synchronize_with(first);
660 * @brief Check whether a model action is enabled.
662 * Checks whether an operation would be successful (i.e., is a lock already
663 * locked, or is the joined thread already complete).
665 * For yield-blocking, yields are never enabled.
667 * @param curr is the ModelAction to check whether it is enabled.
668 * @return a bool that indicates whether the action is enabled.
670 bool ModelExecution::check_action_enabled(ModelAction *curr) {
671 if (curr->is_lock()) {
672 cdsc::mutex *lock = curr->get_mutex();
673 struct cdsc::mutex_state *state = lock->get_state();
676 } else if (curr->is_thread_join()) {
677 Thread *blocking = curr->get_thread_operand();
678 if (!blocking->is_complete()) {
681 } else if (curr->is_sleep()) {
682 if (!fuzzer->shouldSleep(curr))
690 * This is the heart of the model checker routine. It performs model-checking
691 * actions corresponding to a given "current action." Among other processes, it
692 * calculates reads-from relationships, updates synchronization clock vectors,
693 * forms a memory_order constraints graph, and handles replay/backtrack
694 * execution when running permutations of previously-observed executions.
696 * @param curr The current action to process
697 * @return The ModelAction that is actually executed; may be different than
700 ModelAction * ModelExecution::check_current_action(ModelAction *curr)
703 bool second_part_of_rmw = curr->is_rmwc() || curr->is_rmw();
704 bool newly_explored = initialize_curr_action(&curr);
708 wake_up_sleeping_actions(curr);
710 /* Add uninitialized actions to lists */
711 if (!second_part_of_rmw)
712 add_uninit_action_to_lists(curr);
714 SnapVector<ModelAction *> * rf_set = NULL;
715 /* Build may_read_from set for newly-created actions */
716 if (newly_explored && curr->is_read())
717 rf_set = build_may_read_from(curr);
719 if (curr->is_read() && !second_part_of_rmw) {
720 process_read(curr, rf_set);
723 /* bool success = process_read(curr, rf_set);
726 return curr; // Do not add action to lists
729 ASSERT(rf_set == NULL);
731 /* Add the action to lists */
732 if (!second_part_of_rmw)
733 add_action_to_lists(curr);
735 if (curr->is_write())
736 add_write_to_lists(curr);
738 process_thread_action(curr);
740 if (curr->is_write())
743 if (curr->is_fence())
746 if (curr->is_mutex_op())
752 /** Close out a RMWR by converting previous RMWR into a RMW or READ. */
753 ModelAction * ModelExecution::process_rmw(ModelAction *act) {
754 ModelAction *lastread = get_last_action(act->get_tid());
755 lastread->process_rmw(act);
757 mo_graph->addRMWEdge(lastread->get_reads_from(), lastread);
763 * @brief Updates the mo_graph with the constraints imposed from the current
766 * Basic idea is the following: Go through each other thread and find
767 * the last action that happened before our read. Two cases:
769 * -# The action is a write: that write must either occur before
770 * the write we read from or be the write we read from.
771 * -# The action is a read: the write that that action read from
772 * must occur before the write we read from or be the same write.
774 * @param curr The current action. Must be a read.
775 * @param rf The ModelAction or Promise that curr reads from. Must be a write.
776 * @param check_only If true, then only check whether the current action satisfies
777 * read modification order or not, without modifiying priorset and canprune.
779 * @return True if modification order edges were added; false otherwise
782 bool ModelExecution::r_modification_order(ModelAction *curr, const ModelAction *rf,
783 SnapVector<const ModelAction *> * priorset, bool * canprune, bool check_only)
785 SnapVector<action_list_t> *thrd_lists = obj_thrd_map.get(curr->get_location());
787 ASSERT(curr->is_read());
789 /* Last SC fence in the current thread */
790 ModelAction *last_sc_fence_local = get_last_seq_cst_fence(curr->get_tid(), NULL);
792 int tid = curr->get_tid();
793 ModelAction *prev_same_thread = NULL;
794 /* Iterate over all threads */
795 for (i = 0;i < thrd_lists->size();i++, tid = (((unsigned int)(tid+1)) == thrd_lists->size()) ? 0 : tid + 1) {
796 /* Last SC fence in thread tid */
797 ModelAction *last_sc_fence_thread_local = NULL;
799 last_sc_fence_thread_local = get_last_seq_cst_fence(int_to_id(tid), NULL);
801 /* Last SC fence in thread tid, before last SC fence in current thread */
802 ModelAction *last_sc_fence_thread_before = NULL;
803 if (last_sc_fence_local)
804 last_sc_fence_thread_before = get_last_seq_cst_fence(int_to_id(tid), last_sc_fence_local);
806 //Only need to iterate if either hb has changed for thread in question or SC fence after last operation...
807 if (prev_same_thread != NULL &&
808 (prev_same_thread->get_cv()->getClock(tid) == curr->get_cv()->getClock(tid)) &&
809 (last_sc_fence_thread_local == NULL || *last_sc_fence_thread_local < *prev_same_thread)) {
813 /* Iterate over actions in thread, starting from most recent */
814 action_list_t *list = &(*thrd_lists)[tid];
815 sllnode<ModelAction *> * rit;
816 for (rit = list->end();rit != NULL;rit=rit->getPrev()) {
817 ModelAction *act = rit->getVal();
822 /* Don't want to add reflexive edges on 'rf' */
823 if (act->equals(rf)) {
824 if (act->happens_before(curr))
830 if (act->is_write()) {
831 /* C++, Section 29.3 statement 5 */
832 if (curr->is_seqcst() && last_sc_fence_thread_local &&
833 *act < *last_sc_fence_thread_local) {
834 if (mo_graph->checkReachable(rf, act))
837 priorset->push_back(act);
840 /* C++, Section 29.3 statement 4 */
841 else if (act->is_seqcst() && last_sc_fence_local &&
842 *act < *last_sc_fence_local) {
843 if (mo_graph->checkReachable(rf, act))
846 priorset->push_back(act);
849 /* C++, Section 29.3 statement 6 */
850 else if (last_sc_fence_thread_before &&
851 *act < *last_sc_fence_thread_before) {
852 if (mo_graph->checkReachable(rf, act))
855 priorset->push_back(act);
861 * Include at most one act per-thread that "happens
864 if (act->happens_before(curr)) {
866 if (last_sc_fence_local == NULL ||
867 (*last_sc_fence_local < *act)) {
868 prev_same_thread = act;
871 if (act->is_write()) {
872 if (mo_graph->checkReachable(rf, act))
875 priorset->push_back(act);
877 const ModelAction *prevrf = act->get_reads_from();
878 if (!prevrf->equals(rf)) {
879 if (mo_graph->checkReachable(rf, prevrf))
882 priorset->push_back(prevrf);
884 if (act->get_tid() == curr->get_tid()) {
885 //Can prune curr from obj list
899 * Updates the mo_graph with the constraints imposed from the current write.
901 * Basic idea is the following: Go through each other thread and find
902 * the lastest action that happened before our write. Two cases:
904 * (1) The action is a write => that write must occur before
907 * (2) The action is a read => the write that that action read from
908 * must occur before the current write.
910 * This method also handles two other issues:
912 * (I) Sequential Consistency: Making sure that if the current write is
913 * seq_cst, that it occurs after the previous seq_cst write.
915 * (II) Sending the write back to non-synchronizing reads.
917 * @param curr The current action. Must be a write.
918 * @param send_fv A vector for stashing reads to which we may pass our future
919 * value. If NULL, then don't record any future values.
920 * @return True if modification order edges were added; false otherwise
922 void ModelExecution::w_modification_order(ModelAction *curr)
924 SnapVector<action_list_t> *thrd_lists = obj_thrd_map.get(curr->get_location());
926 ASSERT(curr->is_write());
928 SnapList<ModelAction *> edgeset;
930 if (curr->is_seqcst()) {
931 /* We have to at least see the last sequentially consistent write,
932 so we are initialized. */
933 ModelAction *last_seq_cst = get_last_seq_cst_write(curr);
934 if (last_seq_cst != NULL) {
935 edgeset.push_back(last_seq_cst);
937 //update map for next query
938 obj_last_sc_map.put(curr->get_location(), curr);
941 /* Last SC fence in the current thread */
942 ModelAction *last_sc_fence_local = get_last_seq_cst_fence(curr->get_tid(), NULL);
944 /* Iterate over all threads */
945 for (i = 0;i < thrd_lists->size();i++) {
946 /* Last SC fence in thread i, before last SC fence in current thread */
947 ModelAction *last_sc_fence_thread_before = NULL;
948 if (last_sc_fence_local && int_to_id((int)i) != curr->get_tid())
949 last_sc_fence_thread_before = get_last_seq_cst_fence(int_to_id(i), last_sc_fence_local);
951 /* Iterate over actions in thread, starting from most recent */
952 action_list_t *list = &(*thrd_lists)[i];
953 sllnode<ModelAction*>* rit;
954 for (rit = list->end();rit != NULL;rit=rit->getPrev()) {
955 ModelAction *act = rit->getVal();
958 * 1) If RMW and it actually read from something, then we
959 * already have all relevant edges, so just skip to next
962 * 2) If RMW and it didn't read from anything, we should
963 * whatever edge we can get to speed up convergence.
965 * 3) If normal write, we need to look at earlier actions, so
966 * continue processing list.
968 if (curr->is_rmw()) {
969 if (curr->get_reads_from() != NULL)
977 /* C++, Section 29.3 statement 7 */
978 if (last_sc_fence_thread_before && act->is_write() &&
979 *act < *last_sc_fence_thread_before) {
980 edgeset.push_back(act);
985 * Include at most one act per-thread that "happens
988 if (act->happens_before(curr)) {
990 * Note: if act is RMW, just add edge:
992 * The following edge should be handled elsewhere:
993 * readfrom(act) --mo--> act
996 edgeset.push_back(act);
997 else if (act->is_read()) {
998 //if previous read accessed a null, just keep going
999 edgeset.push_back(act->get_reads_from());
1005 mo_graph->addEdges(&edgeset, curr);
1010 * Arbitrary reads from the future are not allowed. Section 29.3 part 9 places
1011 * some constraints. This method checks one the following constraint (others
1012 * require compiler support):
1014 * If X --hb-> Y --mo-> Z, then X should not read from Z.
1015 * If X --hb-> Y, A --rf-> Y, and A --mo-> Z, then X should not read from Z.
1017 bool ModelExecution::mo_may_allow(const ModelAction *writer, const ModelAction *reader)
1019 SnapVector<action_list_t> *thrd_lists = obj_thrd_map.get(reader->get_location());
1021 /* Iterate over all threads */
1022 for (i = 0;i < thrd_lists->size();i++) {
1023 const ModelAction *write_after_read = NULL;
1025 /* Iterate over actions in thread, starting from most recent */
1026 action_list_t *list = &(*thrd_lists)[i];
1027 sllnode<ModelAction *>* rit;
1028 for (rit = list->end();rit != NULL;rit=rit->getPrev()) {
1029 ModelAction *act = rit->getVal();
1031 /* Don't disallow due to act == reader */
1032 if (!reader->happens_before(act) || reader == act)
1034 else if (act->is_write())
1035 write_after_read = act;
1036 else if (act->is_read() && act->get_reads_from() != NULL)
1037 write_after_read = act->get_reads_from();
1040 if (write_after_read && write_after_read != writer && mo_graph->checkReachable(write_after_read, writer))
1047 * Computes the clock vector that happens before propagates from this write.
1049 * @param rf The action that might be part of a release sequence. Must be a
1051 * @return ClockVector of happens before relation.
1054 ClockVector * ModelExecution::get_hb_from_write(ModelAction *rf) const {
1055 SnapVector<ModelAction *> * processset = NULL;
1056 for ( ;rf != NULL;rf = rf->get_reads_from()) {
1057 ASSERT(rf->is_write());
1058 if (!rf->is_rmw() || (rf->is_acquire() && rf->is_release()) || rf->get_rfcv() != NULL)
1060 if (processset == NULL)
1061 processset = new SnapVector<ModelAction *>();
1062 processset->push_back(rf);
1065 int i = (processset == NULL) ? 0 : processset->size();
1067 ClockVector * vec = NULL;
1069 if (rf->get_rfcv() != NULL) {
1070 vec = rf->get_rfcv();
1071 } else if (rf->is_acquire() && rf->is_release()) {
1073 } else if (rf->is_release() && !rf->is_rmw()) {
1075 } else if (rf->is_release()) {
1076 //have rmw that is release and doesn't have a rfcv
1077 (vec = new ClockVector(vec, NULL))->merge(rf->get_cv());
1080 //operation that isn't release
1081 if (rf->get_last_fence_release()) {
1083 vec = rf->get_last_fence_release()->get_cv();
1085 (vec=new ClockVector(vec, NULL))->merge(rf->get_last_fence_release()->get_cv());
1091 rf = (*processset)[i];
1095 if (processset != NULL)
1101 * Performs various bookkeeping operations for the current ModelAction when it is
1102 * the first atomic action occurred at its memory location.
1104 * For instance, adds uninitialized action to the per-object, per-thread action vector
1105 * and to the action trace list of all thread actions.
1107 * @param act is the ModelAction to process.
1109 void ModelExecution::add_uninit_action_to_lists(ModelAction *act)
1111 int tid = id_to_int(act->get_tid());
1112 ModelAction *uninit = NULL;
1114 action_list_t *list = get_safe_ptr_action(&obj_map, act->get_location());
1115 if (list->empty() && act->is_atomic_var()) {
1116 uninit = get_uninitialized_action(act);
1117 uninit_id = id_to_int(uninit->get_tid());
1118 list->push_front(uninit);
1119 SnapVector<action_list_t> *vec = get_safe_ptr_vect_action(&obj_wr_thrd_map, act->get_location());
1120 if ((int)vec->size() <= uninit_id) {
1121 int oldsize = (int) vec->size();
1122 vec->resize(uninit_id + 1);
1123 for(int i = oldsize;i < uninit_id + 1;i++) {
1124 new (&(*vec)[i]) action_list_t();
1127 (*vec)[uninit_id].push_front(uninit);
1130 // Update action trace, a total order of all actions
1132 action_trace.push_front(uninit);
1134 // Update obj_thrd_map, a per location, per thread, order of actions
1135 SnapVector<action_list_t> *vec = get_safe_ptr_vect_action(&obj_thrd_map, act->get_location());
1136 if ((int)vec->size() <= tid) {
1137 uint oldsize = vec->size();
1138 vec->resize(priv->next_thread_id);
1139 for(uint i = oldsize;i < priv->next_thread_id;i++)
1140 new (&(*vec)[i]) action_list_t();
1143 (*vec)[uninit_id].push_front(uninit);
1145 // Update thrd_last_action, the last action taken by each thrad
1146 if ((int)thrd_last_action.size() <= tid)
1147 thrd_last_action.resize(get_num_threads());
1149 thrd_last_action[uninit_id] = uninit;
1154 * Performs various bookkeeping operations for the current ModelAction. For
1155 * instance, adds action to the per-object, per-thread action vector and to the
1156 * action trace list of all thread actions.
1158 * @param act is the ModelAction to add.
1160 void ModelExecution::add_action_to_lists(ModelAction *act)
1162 int tid = id_to_int(act->get_tid());
1163 action_list_t *list = get_safe_ptr_action(&obj_map, act->get_location());
1164 list->push_back(act);
1166 // Update action trace, a total order of all actions
1167 action_trace.push_back(act);
1169 // Update obj_thrd_map, a per location, per thread, order of actions
1170 SnapVector<action_list_t> *vec = get_safe_ptr_vect_action(&obj_thrd_map, act->get_location());
1171 if ((int)vec->size() <= tid) {
1172 uint oldsize = vec->size();
1173 vec->resize(priv->next_thread_id);
1174 for(uint i = oldsize;i < priv->next_thread_id;i++)
1175 new (&(*vec)[i]) action_list_t();
1177 (*vec)[tid].push_back(act);
1179 // Update thrd_last_action, the last action taken by each thrad
1180 if ((int)thrd_last_action.size() <= tid)
1181 thrd_last_action.resize(get_num_threads());
1182 thrd_last_action[tid] = act;
1184 // Update thrd_last_fence_release, the last release fence taken by each thread
1185 if (act->is_fence() && act->is_release()) {
1186 if ((int)thrd_last_fence_release.size() <= tid)
1187 thrd_last_fence_release.resize(get_num_threads());
1188 thrd_last_fence_release[tid] = act;
1191 if (act->is_wait()) {
1192 void *mutex_loc = (void *) act->get_value();
1193 get_safe_ptr_action(&obj_map, mutex_loc)->push_back(act);
1195 SnapVector<action_list_t> *vec = get_safe_ptr_vect_action(&obj_thrd_map, mutex_loc);
1196 if ((int)vec->size() <= tid) {
1197 uint oldsize = vec->size();
1198 vec->resize(priv->next_thread_id);
1199 for(uint i = oldsize;i < priv->next_thread_id;i++)
1200 new (&(*vec)[i]) action_list_t();
1202 (*vec)[tid].push_back(act);
1206 void insertIntoActionList(action_list_t *list, ModelAction *act) {
1207 sllnode<ModelAction*> * rit = list->end();
1208 modelclock_t next_seq = act->get_seq_number();
1209 if (rit == NULL || (rit->getVal()->get_seq_number() == next_seq))
1210 list->push_back(act);
1212 for(;rit != NULL;rit=rit->getPrev()) {
1213 if (rit->getVal()->get_seq_number() == next_seq) {
1214 list->insertAfter(rit, act);
1221 void insertIntoActionListAndSetCV(action_list_t *list, ModelAction *act) {
1222 sllnode<ModelAction*> * rit = list->end();
1223 modelclock_t next_seq = act->get_seq_number();
1225 act->create_cv(NULL);
1226 } else if (rit->getVal()->get_seq_number() == next_seq) {
1227 act->create_cv(rit->getVal());
1228 list->push_back(act);
1230 for(;rit != NULL;rit=rit->getPrev()) {
1231 if (rit->getVal()->get_seq_number() == next_seq) {
1232 act->create_cv(rit->getVal());
1233 list->insertAfter(rit, act);
1241 * Performs various bookkeeping operations for a normal write. The
1242 * complication is that we are typically inserting a normal write
1243 * lazily, so we need to insert it into the middle of lists.
1245 * @param act is the ModelAction to add.
1248 void ModelExecution::add_normal_write_to_lists(ModelAction *act)
1250 int tid = id_to_int(act->get_tid());
1251 insertIntoActionListAndSetCV(&action_trace, act);
1253 action_list_t *list = get_safe_ptr_action(&obj_map, act->get_location());
1254 insertIntoActionList(list, act);
1256 // Update obj_thrd_map, a per location, per thread, order of actions
1257 SnapVector<action_list_t> *vec = get_safe_ptr_vect_action(&obj_thrd_map, act->get_location());
1258 if (tid >= (int)vec->size()) {
1259 uint oldsize =vec->size();
1260 vec->resize(priv->next_thread_id);
1261 for(uint i=oldsize;i<priv->next_thread_id;i++)
1262 new (&(*vec)[i]) action_list_t();
1264 insertIntoActionList(&(*vec)[tid],act);
1266 // Update thrd_last_action, the last action taken by each thrad
1267 if (thrd_last_action[tid]->get_seq_number() == act->get_seq_number())
1268 thrd_last_action[tid] = act;
1272 void ModelExecution::add_write_to_lists(ModelAction *write) {
1273 SnapVector<action_list_t> *vec = get_safe_ptr_vect_action(&obj_wr_thrd_map, write->get_location());
1274 int tid = id_to_int(write->get_tid());
1275 if (tid >= (int)vec->size()) {
1276 uint oldsize =vec->size();
1277 vec->resize(priv->next_thread_id);
1278 for(uint i=oldsize;i<priv->next_thread_id;i++)
1279 new (&(*vec)[i]) action_list_t();
1281 (*vec)[tid].push_back(write);
1285 * @brief Get the last action performed by a particular Thread
1286 * @param tid The thread ID of the Thread in question
1287 * @return The last action in the thread
1289 ModelAction * ModelExecution::get_last_action(thread_id_t tid) const
1291 int threadid = id_to_int(tid);
1292 if (threadid < (int)thrd_last_action.size())
1293 return thrd_last_action[id_to_int(tid)];
1299 * @brief Get the last fence release performed by a particular Thread
1300 * @param tid The thread ID of the Thread in question
1301 * @return The last fence release in the thread, if one exists; NULL otherwise
1303 ModelAction * ModelExecution::get_last_fence_release(thread_id_t tid) const
1305 int threadid = id_to_int(tid);
1306 if (threadid < (int)thrd_last_fence_release.size())
1307 return thrd_last_fence_release[id_to_int(tid)];
1313 * Gets the last memory_order_seq_cst write (in the total global sequence)
1314 * performed on a particular object (i.e., memory location), not including the
1316 * @param curr The current ModelAction; also denotes the object location to
1318 * @return The last seq_cst write
1320 ModelAction * ModelExecution::get_last_seq_cst_write(ModelAction *curr) const
1322 void *location = curr->get_location();
1323 return obj_last_sc_map.get(location);
1327 * Gets the last memory_order_seq_cst fence (in the total global sequence)
1328 * performed in a particular thread, prior to a particular fence.
1329 * @param tid The ID of the thread to check
1330 * @param before_fence The fence from which to begin the search; if NULL, then
1331 * search for the most recent fence in the thread.
1332 * @return The last prior seq_cst fence in the thread, if exists; otherwise, NULL
1334 ModelAction * ModelExecution::get_last_seq_cst_fence(thread_id_t tid, const ModelAction *before_fence) const
1336 /* All fences should have location FENCE_LOCATION */
1337 action_list_t *list = obj_map.get(FENCE_LOCATION);
1342 sllnode<ModelAction*>* rit = list->end();
1345 for (;rit != NULL;rit=rit->getPrev())
1346 if (rit->getVal() == before_fence)
1349 ASSERT(rit->getVal() == before_fence);
1353 for (;rit != NULL;rit=rit->getPrev()) {
1354 ModelAction *act = rit->getVal();
1355 if (act->is_fence() && (tid == act->get_tid()) && act->is_seqcst())
1362 * Gets the last unlock operation performed on a particular mutex (i.e., memory
1363 * location). This function identifies the mutex according to the current
1364 * action, which is presumed to perform on the same mutex.
1365 * @param curr The current ModelAction; also denotes the object location to
1367 * @return The last unlock operation
1369 ModelAction * ModelExecution::get_last_unlock(ModelAction *curr) const
1371 void *location = curr->get_location();
1373 action_list_t *list = obj_map.get(location);
1374 /* Find: max({i in dom(S) | isUnlock(t_i) && samevar(t_i, t)}) */
1375 sllnode<ModelAction*>* rit;
1376 for (rit = list->end();rit != NULL;rit=rit->getPrev())
1377 if (rit->getVal()->is_unlock() || rit->getVal()->is_wait())
1378 return rit->getVal();
1382 ModelAction * ModelExecution::get_parent_action(thread_id_t tid) const
1384 ModelAction *parent = get_last_action(tid);
1386 parent = get_thread(tid)->get_creation();
1391 * Returns the clock vector for a given thread.
1392 * @param tid The thread whose clock vector we want
1393 * @return Desired clock vector
1395 ClockVector * ModelExecution::get_cv(thread_id_t tid) const
1397 ModelAction *firstaction=get_parent_action(tid);
1398 return firstaction != NULL ? firstaction->get_cv() : NULL;
1401 bool valequals(uint64_t val1, uint64_t val2, int size) {
1404 return ((uint8_t)val1) == ((uint8_t)val2);
1406 return ((uint16_t)val1) == ((uint16_t)val2);
1408 return ((uint32_t)val1) == ((uint32_t)val2);
1418 * Build up an initial set of all past writes that this 'read' action may read
1419 * from, as well as any previously-observed future values that must still be valid.
1421 * @param curr is the current ModelAction that we are exploring; it must be a
1424 SnapVector<ModelAction *> * ModelExecution::build_may_read_from(ModelAction *curr)
1426 SnapVector<action_list_t> *thrd_lists = obj_wr_thrd_map.get(curr->get_location());
1428 ASSERT(curr->is_read());
1430 ModelAction *last_sc_write = NULL;
1432 if (curr->is_seqcst())
1433 last_sc_write = get_last_seq_cst_write(curr);
1435 SnapVector<ModelAction *> * rf_set = new SnapVector<ModelAction *>();
1437 /* Iterate over all threads */
1438 for (i = 0;i < thrd_lists->size();i++) {
1439 /* Iterate over actions in thread, starting from most recent */
1440 action_list_t *list = &(*thrd_lists)[i];
1441 sllnode<ModelAction *> * rit;
1442 for (rit = list->end();rit != NULL;rit=rit->getPrev()) {
1443 ModelAction *act = rit->getVal();
1448 /* Don't consider more than one seq_cst write if we are a seq_cst read. */
1449 bool allow_read = true;
1451 if (curr->is_seqcst() && (act->is_seqcst() || (last_sc_write != NULL && act->happens_before(last_sc_write))) && act != last_sc_write)
1454 /* Need to check whether we will have two RMW reading from the same value */
1455 if (curr->is_rmwr()) {
1456 /* It is okay if we have a failing CAS */
1457 if (!curr->is_rmwrcas() ||
1458 valequals(curr->get_value(), act->get_value(), curr->getSize())) {
1459 //Need to make sure we aren't the second RMW
1460 CycleNode * node = mo_graph->getNode_noCreate(act);
1461 if (node != NULL && node->getRMW() != NULL) {
1462 //we are the second RMW
1469 /* Only add feasible reads */
1470 rf_set->push_back(act);
1473 /* Include at most one act per-thread that "happens before" curr */
1474 if (act->happens_before(curr))
1479 if (DBG_ENABLED()) {
1480 model_print("Reached read action:\n");
1482 model_print("End printing read_from_past\n");
1488 * @brief Get an action representing an uninitialized atomic
1490 * This function may create a new one.
1492 * @param curr The current action, which prompts the creation of an UNINIT action
1493 * @return A pointer to the UNINIT ModelAction
1495 ModelAction * ModelExecution::get_uninitialized_action(ModelAction *curr) const
1497 ModelAction *act = curr->get_uninit_action();
1499 act = new ModelAction(ATOMIC_UNINIT, std::memory_order_relaxed, curr->get_location(), params->uninitvalue, model_thread);
1500 curr->set_uninit_action(act);
1502 act->create_cv(NULL);
1506 static void print_list(action_list_t *list)
1508 sllnode<ModelAction*> *it;
1510 model_print("------------------------------------------------------------------------------------\n");
1511 model_print("# t Action type MO Location Value Rf CV\n");
1512 model_print("------------------------------------------------------------------------------------\n");
1514 unsigned int hash = 0;
1516 for (it = list->begin();it != NULL;it=it->getNext()) {
1517 const ModelAction *act = it->getVal();
1518 if (act->get_seq_number() > 0)
1520 hash = hash^(hash<<3)^(it->getVal()->hash());
1522 model_print("HASH %u\n", hash);
1523 model_print("------------------------------------------------------------------------------------\n");
1526 #if SUPPORT_MOD_ORDER_DUMP
1527 void ModelExecution::dumpGraph(char *filename)
1530 sprintf(buffer, "%s.dot", filename);
1531 FILE *file = fopen(buffer, "w");
1532 fprintf(file, "digraph %s {\n", filename);
1533 mo_graph->dumpNodes(file);
1534 ModelAction **thread_array = (ModelAction **)model_calloc(1, sizeof(ModelAction *) * get_num_threads());
1536 for (sllnode<ModelAction*>* it = action_trace.begin();it != NULL;it=it->getNext()) {
1537 ModelAction *act = it->getVal();
1538 if (act->is_read()) {
1539 mo_graph->dot_print_node(file, act);
1540 mo_graph->dot_print_edge(file,
1541 act->get_reads_from(),
1543 "label=\"rf\", color=red, weight=2");
1545 if (thread_array[act->get_tid()]) {
1546 mo_graph->dot_print_edge(file,
1547 thread_array[id_to_int(act->get_tid())],
1549 "label=\"sb\", color=blue, weight=400");
1552 thread_array[act->get_tid()] = act;
1554 fprintf(file, "}\n");
1555 model_free(thread_array);
1560 /** @brief Prints an execution trace summary. */
1561 void ModelExecution::print_summary()
1563 #if SUPPORT_MOD_ORDER_DUMP
1564 char buffername[100];
1565 sprintf(buffername, "exec%04u", get_execution_number());
1566 mo_graph->dumpGraphToFile(buffername);
1567 sprintf(buffername, "graph%04u", get_execution_number());
1568 dumpGraph(buffername);
1571 model_print("Execution trace %d:", get_execution_number());
1572 if (scheduler->all_threads_sleeping())
1573 model_print(" SLEEP-SET REDUNDANT");
1574 if (have_bug_reports())
1575 model_print(" DETECTED BUG(S)");
1579 print_list(&action_trace);
1585 * Add a Thread to the system for the first time. Should only be called once
1587 * @param t The Thread to add
1589 void ModelExecution::add_thread(Thread *t)
1591 unsigned int i = id_to_int(t->get_id());
1592 if (i >= thread_map.size())
1593 thread_map.resize(i + 1);
1595 if (!t->is_model_thread())
1596 scheduler->add_thread(t);
1600 * @brief Get a Thread reference by its ID
1601 * @param tid The Thread's ID
1602 * @return A Thread reference
1604 Thread * ModelExecution::get_thread(thread_id_t tid) const
1606 unsigned int i = id_to_int(tid);
1607 if (i < thread_map.size())
1608 return thread_map[i];
1613 * @brief Get a reference to the Thread in which a ModelAction was executed
1614 * @param act The ModelAction
1615 * @return A Thread reference
1617 Thread * ModelExecution::get_thread(const ModelAction *act) const
1619 return get_thread(act->get_tid());
1623 * @brief Get a Thread reference by its pthread ID
1624 * @param index The pthread's ID
1625 * @return A Thread reference
1627 Thread * ModelExecution::get_pthread(pthread_t pid) {
1633 uint32_t thread_id = x.v;
1634 if (thread_id < pthread_counter + 1) return pthread_map[thread_id];
1639 * @brief Check if a Thread is currently enabled
1640 * @param t The Thread to check
1641 * @return True if the Thread is currently enabled
1643 bool ModelExecution::is_enabled(Thread *t) const
1645 return scheduler->is_enabled(t);
1649 * @brief Check if a Thread is currently enabled
1650 * @param tid The ID of the Thread to check
1651 * @return True if the Thread is currently enabled
1653 bool ModelExecution::is_enabled(thread_id_t tid) const
1655 return scheduler->is_enabled(tid);
1659 * @brief Select the next thread to execute based on the curren action
1661 * RMW actions occur in two parts, and we cannot split them. And THREAD_CREATE
1662 * actions should be followed by the execution of their child thread. In either
1663 * case, the current action should determine the next thread schedule.
1665 * @param curr The current action
1666 * @return The next thread to run, if the current action will determine this
1667 * selection; otherwise NULL
1669 Thread * ModelExecution::action_select_next_thread(const ModelAction *curr) const
1671 /* Do not split atomic RMW */
1672 if (curr->is_rmwr() && !paused_by_fuzzer(curr))
1673 return get_thread(curr);
1674 /* Follow CREATE with the created thread */
1675 /* which is not needed, because model.cc takes care of this */
1676 if (curr->get_type() == THREAD_CREATE)
1677 return curr->get_thread_operand();
1678 if (curr->get_type() == PTHREAD_CREATE) {
1679 return curr->get_thread_operand();
1684 /** @param act A read atomic action */
1685 bool ModelExecution::paused_by_fuzzer(const ModelAction * act) const
1687 ASSERT(act->is_read());
1689 // Actions paused by fuzzer have their sequence number reset to 0
1690 return act->get_seq_number() == 0;
1694 * Takes the next step in the execution, if possible.
1695 * @param curr The current step to take
1696 * @return Returns the next Thread to run, if any; NULL if this execution
1699 Thread * ModelExecution::take_step(ModelAction *curr)
1701 Thread *curr_thrd = get_thread(curr);
1702 ASSERT(curr_thrd->get_state() == THREAD_READY);
1704 ASSERT(check_action_enabled(curr)); /* May have side effects? */
1705 curr = check_current_action(curr);
1708 /* Process this action in ModelHistory for records */
1709 // model->get_history()->process_action( curr, curr->get_tid() );
1711 if (curr_thrd->is_blocked() || curr_thrd->is_complete())
1712 scheduler->remove_thread(curr_thrd);
1714 return action_select_next_thread(curr);
1717 Fuzzer * ModelExecution::getFuzzer() {