11 #include "clockvector.h"
12 #include "cyclegraph.h"
14 #include "threads-model.h"
15 #include "bugmessage.h"
19 #define INITIAL_THREAD_ID 0
22 * Structure for holding small ModelChecker members that should be snapshotted
24 struct model_snapshot_members {
25 model_snapshot_members() :
26 /* First thread created will have id INITIAL_THREAD_ID */
27 next_thread_id(INITIAL_THREAD_ID),
28 used_sequence_numbers(0),
30 bad_synchronization(false),
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 */
44 bool bad_synchronization;
50 /** @brief Constructor */
51 ModelExecution::ModelExecution(ModelChecker *m, Scheduler *scheduler) :
56 thread_map(2), /* We'll always need at least 2 threads */
60 condvar_waiters_map(),
64 thrd_last_fence_release(),
65 priv(new struct model_snapshot_members ()),
66 mo_graph(new CycleGraph()),
69 thrd_func_inst_lists()
71 /* Initialize a model-checker thread, for special ModelActions */
72 model_thread = new Thread(get_next_id());
73 add_thread(model_thread);
74 scheduler->register_engine(this);
77 /** @brief Destructor */
78 ModelExecution::~ModelExecution()
80 for (unsigned int i = 0;i < get_num_threads();i++)
81 delete get_thread(int_to_id(i));
87 int ModelExecution::get_execution_number() const
89 return model->get_execution_number();
92 static action_list_t * get_safe_ptr_action(HashTable<const void *, action_list_t *, uintptr_t, 4> * hash, void * ptr)
94 action_list_t *tmp = hash->get(ptr);
96 tmp = new action_list_t();
102 static SnapVector<action_list_t> * get_safe_ptr_vect_action(HashTable<const void *, SnapVector<action_list_t> *, uintptr_t, 4> * hash, void * ptr)
104 SnapVector<action_list_t> *tmp = hash->get(ptr);
106 tmp = new SnapVector<action_list_t>();
112 /** @return a thread ID for a new Thread */
113 thread_id_t ModelExecution::get_next_id()
115 return priv->next_thread_id++;
118 /** @return the number of user threads created during this execution */
119 unsigned int ModelExecution::get_num_threads() const
121 return priv->next_thread_id;
124 /** @return a sequence number for a new ModelAction */
125 modelclock_t ModelExecution::get_next_seq_num()
127 return ++priv->used_sequence_numbers;
131 * @brief Should the current action wake up a given thread?
133 * @param curr The current action
134 * @param thread The thread that we might wake up
135 * @return True, if we should wake up the sleeping thread; false otherwise
137 bool ModelExecution::should_wake_up(const ModelAction *curr, const Thread *thread) const
139 const ModelAction *asleep = thread->get_pending();
140 /* Don't allow partial RMW to wake anyone up */
143 /* Synchronizing actions may have been backtracked */
144 if (asleep->could_synchronize_with(curr))
146 /* All acquire/release fences and fence-acquire/store-release */
147 if (asleep->is_fence() && asleep->is_acquire() && curr->is_release())
149 /* Fence-release + store can awake load-acquire on the same location */
150 if (asleep->is_read() && asleep->is_acquire() && curr->same_var(asleep) && curr->is_write()) {
151 ModelAction *fence_release = get_last_fence_release(curr->get_tid());
152 if (fence_release && *(get_last_action(thread->get_id())) < *fence_release)
158 void ModelExecution::wake_up_sleeping_actions(ModelAction *curr)
160 for (unsigned int i = 0;i < get_num_threads();i++) {
161 Thread *thr = get_thread(int_to_id(i));
162 if (scheduler->is_sleep_set(thr)) {
163 if (should_wake_up(curr, thr))
164 /* Remove this thread from sleep set */
165 scheduler->remove_sleep(thr);
170 /** @brief Alert the model-checker that an incorrectly-ordered
171 * synchronization was made */
172 void ModelExecution::set_bad_synchronization()
174 priv->bad_synchronization = true;
177 bool ModelExecution::assert_bug(const char *msg)
179 priv->bugs.push_back(new bug_message(msg));
181 if (isfeasibleprefix()) {
188 /** @return True, if any bugs have been reported for this execution */
189 bool ModelExecution::have_bug_reports() const
191 return priv->bugs.size() != 0;
194 /** @return True, if any fatal bugs have been reported for this execution.
195 * Any bug other than a data race is considered a fatal bug. Data races
196 * are not considered fatal unless the number of races is exceeds
197 * a threshold (temporarily set as 15).
199 bool ModelExecution::have_fatal_bug_reports() const
201 return priv->bugs.size() != 0;
204 SnapVector<bug_message *> * ModelExecution::get_bugs() const
210 * Check whether the current trace has triggered an assertion which should halt
213 * @return True, if the execution should be aborted; false otherwise
215 bool ModelExecution::has_asserted() const
217 return priv->asserted;
221 * Trigger a trace assertion which should cause this execution to be halted.
222 * This can be due to a detected bug or due to an infeasibility that should
225 void ModelExecution::set_assert()
227 priv->asserted = true;
231 * Check if we are in a deadlock. Should only be called at the end of an
232 * execution, although it should not give false positives in the middle of an
233 * execution (there should be some ENABLED thread).
235 * @return True if program is in a deadlock; false otherwise
237 bool ModelExecution::is_deadlocked() const
239 bool blocking_threads = false;
240 for (unsigned int i = 0;i < get_num_threads();i++) {
241 thread_id_t tid = int_to_id(i);
244 Thread *t = get_thread(tid);
245 if (!t->is_model_thread() && t->get_pending())
246 blocking_threads = true;
248 return blocking_threads;
252 * Check if this is a complete execution. That is, have all thread completed
253 * execution (rather than exiting because sleep sets have forced a redundant
256 * @return True if the execution is complete.
258 bool ModelExecution::is_complete_execution() const
260 for (unsigned int i = 0;i < get_num_threads();i++)
261 if (is_enabled(int_to_id(i)))
266 ModelAction * ModelExecution::convertNonAtomicStore(void * location) {
267 uint64_t value = *((const uint64_t *) location);
268 modelclock_t storeclock;
269 thread_id_t storethread;
270 getStoreThreadAndClock(location, &storethread, &storeclock);
271 setAtomicStoreFlag(location);
272 ModelAction * act = new ModelAction(NONATOMIC_WRITE, memory_order_relaxed, location, value, get_thread(storethread));
273 act->set_seq_number(storeclock);
274 add_normal_write_to_lists(act);
275 add_write_to_lists(act);
276 w_modification_order(act);
282 * Processes a read model action.
283 * @param curr is the read model action to process.
284 * @param rf_set is the set of model actions we can possibly read from
285 * @return True if processing this read updates the mo_graph.
287 void ModelExecution::process_read(ModelAction *curr, SnapVector<ModelAction *> * rf_set)
289 SnapVector<const ModelAction *> * priorset = new SnapVector<const ModelAction *>();
290 bool hasnonatomicstore = hasNonAtomicStore(curr->get_location());
291 if (hasnonatomicstore) {
292 ModelAction * nonatomicstore = convertNonAtomicStore(curr->get_location());
293 rf_set->push_back(nonatomicstore);
297 int index = fuzzer->selectWrite(curr, rf_set);
298 ModelAction *rf = (*rf_set)[index];
302 bool canprune = false;
303 if (r_modification_order(curr, rf, priorset, &canprune)) {
304 for(unsigned int i=0;i<priorset->size();i++) {
305 mo_graph->addEdge((*priorset)[i], rf);
308 get_thread(curr)->set_return_value(curr->get_return_value());
310 if (canprune && curr->get_type() == ATOMIC_READ) {
311 int tid = id_to_int(curr->get_tid());
312 (*obj_thrd_map.get(curr->get_location()))[tid].pop_back();
317 (*rf_set)[index] = rf_set->back();
323 * Processes a lock, trylock, or unlock model action. @param curr is
324 * the read model action to process.
326 * The try lock operation checks whether the lock is taken. If not,
327 * it falls to the normal lock operation case. If so, it returns
330 * The lock operation has already been checked that it is enabled, so
331 * it just grabs the lock and synchronizes with the previous unlock.
333 * The unlock operation has to re-enable all of the threads that are
334 * waiting on the lock.
336 * @return True if synchronization was updated; false otherwise
338 bool ModelExecution::process_mutex(ModelAction *curr)
340 cdsc::mutex *mutex = curr->get_mutex();
341 struct cdsc::mutex_state *state = NULL;
344 state = mutex->get_state();
346 switch (curr->get_type()) {
347 case ATOMIC_TRYLOCK: {
348 bool success = !state->locked;
349 curr->set_try_lock(success);
351 get_thread(curr)->set_return_value(0);
354 get_thread(curr)->set_return_value(1);
356 //otherwise fall into the lock case
358 //TODO: FIND SOME BETTER WAY TO CHECK LOCK INITIALIZED OR NOT
359 //if (curr->get_cv()->getClock(state->alloc_tid) <= state->alloc_clock)
360 // assert_bug("Lock access before initialization");
361 state->locked = get_thread(curr);
362 ModelAction *unlock = get_last_unlock(curr);
363 //synchronize with the previous unlock statement
364 if (unlock != NULL) {
365 synchronize(unlock, curr);
371 case ATOMIC_UNLOCK: {
372 //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...
374 /* wake up the other threads */
375 for (unsigned int i = 0;i < get_num_threads();i++) {
376 Thread *t = get_thread(int_to_id(i));
377 Thread *curr_thrd = get_thread(curr);
378 if (t->waiting_on() == curr_thrd && t->get_pending()->is_lock())
382 /* unlock the lock - after checking who was waiting on it */
383 state->locked = NULL;
385 if (!curr->is_wait())
386 break;/* The rest is only for ATOMIC_WAIT */
390 case ATOMIC_NOTIFY_ALL: {
391 action_list_t *waiters = get_safe_ptr_action(&condvar_waiters_map, curr->get_location());
392 //activate all the waiting threads
393 for (action_list_t::iterator rit = waiters->begin();rit != waiters->end();rit++) {
394 scheduler->wake(get_thread(*rit));
399 case ATOMIC_NOTIFY_ONE: {
400 action_list_t *waiters = get_safe_ptr_action(&condvar_waiters_map, curr->get_location());
401 if (waiters->size() != 0) {
402 Thread * thread = fuzzer->selectNotify(waiters);
403 scheduler->wake(thread);
415 * Process a write ModelAction
416 * @param curr The ModelAction to process
417 * @return True if the mo_graph was updated or promises were resolved
419 void ModelExecution::process_write(ModelAction *curr)
421 w_modification_order(curr);
422 get_thread(curr)->set_return_value(VALUE_NONE);
426 * Process a fence ModelAction
427 * @param curr The ModelAction to process
428 * @return True if synchronization was updated
430 bool ModelExecution::process_fence(ModelAction *curr)
433 * fence-relaxed: no-op
434 * fence-release: only log the occurence (not in this function), for
435 * use in later synchronization
436 * fence-acquire (this function): search for hypothetical release
438 * fence-seq-cst: MO constraints formed in {r,w}_modification_order
440 bool updated = false;
441 if (curr->is_acquire()) {
442 action_list_t *list = &action_trace;
443 action_list_t::reverse_iterator rit;
444 /* Find X : is_read(X) && X --sb-> curr */
445 for (rit = list->rbegin();rit != list->rend();rit++) {
446 ModelAction *act = *rit;
449 if (act->get_tid() != curr->get_tid())
451 /* Stop at the beginning of the thread */
452 if (act->is_thread_start())
454 /* Stop once we reach a prior fence-acquire */
455 if (act->is_fence() && act->is_acquire())
459 /* read-acquire will find its own release sequences */
460 if (act->is_acquire())
463 /* Establish hypothetical release sequences */
464 ClockVector *cv = get_hb_from_write(act->get_reads_from());
465 if (cv != NULL && curr->get_cv()->merge(cv))
473 * @brief Process the current action for thread-related activity
475 * Performs current-action processing for a THREAD_* ModelAction. Proccesses
476 * may include setting Thread status, completing THREAD_FINISH/THREAD_JOIN
477 * synchronization, etc. This function is a no-op for non-THREAD actions
478 * (e.g., ATOMIC_{READ,WRITE,RMW,LOCK}, etc.)
480 * @param curr The current action
481 * @return True if synchronization was updated or a thread completed
483 bool ModelExecution::process_thread_action(ModelAction *curr)
485 bool updated = false;
487 switch (curr->get_type()) {
488 case THREAD_CREATE: {
489 thrd_t *thrd = (thrd_t *)curr->get_location();
490 struct thread_params *params = (struct thread_params *)curr->get_value();
491 Thread *th = new Thread(get_next_id(), thrd, params->func, params->arg, get_thread(curr));
492 curr->set_thread_operand(th);
494 th->set_creation(curr);
497 case PTHREAD_CREATE: {
498 (*(uint32_t *)curr->get_location()) = pthread_counter++;
500 struct pthread_params *params = (struct pthread_params *)curr->get_value();
501 Thread *th = new Thread(get_next_id(), NULL, params->func, params->arg, get_thread(curr));
502 curr->set_thread_operand(th);
504 th->set_creation(curr);
506 if ( pthread_map.size() < pthread_counter )
507 pthread_map.resize( pthread_counter );
508 pthread_map[ pthread_counter-1 ] = th;
513 Thread *blocking = curr->get_thread_operand();
514 ModelAction *act = get_last_action(blocking->get_id());
515 synchronize(act, curr);
516 updated = true; /* trigger rel-seq checks */
520 Thread *blocking = curr->get_thread_operand();
521 ModelAction *act = get_last_action(blocking->get_id());
522 synchronize(act, curr);
523 updated = true; /* trigger rel-seq checks */
524 break; // WL: to be add (modified)
527 case THREAD_FINISH: {
528 Thread *th = get_thread(curr);
529 /* Wake up any joining threads */
530 for (unsigned int i = 0;i < get_num_threads();i++) {
531 Thread *waiting = get_thread(int_to_id(i));
532 if (waiting->waiting_on() == th &&
533 waiting->get_pending()->is_thread_join())
534 scheduler->wake(waiting);
537 updated = true; /* trigger rel-seq checks */
551 * Initialize the current action by performing one or more of the following
552 * actions, as appropriate: merging RMWR and RMWC/RMW actions,
553 * manipulating backtracking sets, allocating and
554 * initializing clock vectors, and computing the promises to fulfill.
556 * @param curr The current action, as passed from the user context; may be
557 * freed/invalidated after the execution of this function, with a different
558 * action "returned" its place (pass-by-reference)
559 * @return True if curr is a newly-explored action; false otherwise
561 bool ModelExecution::initialize_curr_action(ModelAction **curr)
563 if ((*curr)->is_rmwc() || (*curr)->is_rmw()) {
564 ModelAction *newcurr = process_rmw(*curr);
570 ModelAction *newcurr = *curr;
572 newcurr->set_seq_number(get_next_seq_num());
573 /* Always compute new clock vector */
574 newcurr->create_cv(get_parent_action(newcurr->get_tid()));
576 /* Assign most recent release fence */
577 newcurr->set_last_fence_release(get_last_fence_release(newcurr->get_tid()));
579 return true; /* This was a new ModelAction */
584 * @brief Establish reads-from relation between two actions
586 * Perform basic operations involved with establishing a concrete rf relation,
587 * including setting the ModelAction data and checking for release sequences.
589 * @param act The action that is reading (must be a read)
590 * @param rf The action from which we are reading (must be a write)
592 * @return True if this read established synchronization
595 void ModelExecution::read_from(ModelAction *act, ModelAction *rf)
598 ASSERT(rf->is_write());
600 act->set_read_from(rf);
601 if (act->is_acquire()) {
602 ClockVector *cv = get_hb_from_write(rf);
605 act->get_cv()->merge(cv);
610 * @brief Synchronizes two actions
612 * When A synchronizes with B (or A --sw-> B), B inherits A's clock vector.
613 * This function performs the synchronization as well as providing other hooks
614 * for other checks along with synchronization.
616 * @param first The left-hand side of the synchronizes-with relation
617 * @param second The right-hand side of the synchronizes-with relation
618 * @return True if the synchronization was successful (i.e., was consistent
619 * with the execution order); false otherwise
621 bool ModelExecution::synchronize(const ModelAction *first, ModelAction *second)
623 if (*second < *first) {
624 set_bad_synchronization();
627 return second->synchronize_with(first);
631 * @brief Check whether a model action is enabled.
633 * Checks whether an operation would be successful (i.e., is a lock already
634 * locked, or is the joined thread already complete).
636 * For yield-blocking, yields are never enabled.
638 * @param curr is the ModelAction to check whether it is enabled.
639 * @return a bool that indicates whether the action is enabled.
641 bool ModelExecution::check_action_enabled(ModelAction *curr) {
642 if (curr->is_lock()) {
643 cdsc::mutex *lock = curr->get_mutex();
644 struct cdsc::mutex_state *state = lock->get_state();
647 } else if (curr->is_thread_join()) {
648 Thread *blocking = curr->get_thread_operand();
649 if (!blocking->is_complete()) {
658 * This is the heart of the model checker routine. It performs model-checking
659 * actions corresponding to a given "current action." Among other processes, it
660 * calculates reads-from relationships, updates synchronization clock vectors,
661 * forms a memory_order constraints graph, and handles replay/backtrack
662 * execution when running permutations of previously-observed executions.
664 * @param curr The current action to process
665 * @return The ModelAction that is actually executed; may be different than
668 ModelAction * ModelExecution::check_current_action(ModelAction *curr)
671 bool second_part_of_rmw = curr->is_rmwc() || curr->is_rmw();
672 bool newly_explored = initialize_curr_action(&curr);
676 wake_up_sleeping_actions(curr);
678 /* Add the action to lists before any other model-checking tasks */
679 if (!second_part_of_rmw && curr->get_type() != NOOP)
680 add_action_to_lists(curr);
682 if (curr->is_write())
683 add_write_to_lists(curr);
685 SnapVector<ModelAction *> * rf_set = NULL;
686 /* Build may_read_from set for newly-created actions */
687 if (newly_explored && curr->is_read())
688 rf_set = build_may_read_from(curr);
690 process_thread_action(curr);
692 if (curr->is_read() && !second_part_of_rmw) {
693 process_read(curr, rf_set);
696 ASSERT(rf_set == NULL);
699 if (curr->is_write())
702 if (curr->is_fence())
705 if (curr->is_mutex_op())
712 * This is the strongest feasibility check available.
713 * @return whether the current trace (partial or complete) must be a prefix of
716 bool ModelExecution::isfeasibleprefix() const
718 return !is_infeasible();
722 * Print disagnostic information about an infeasible execution
723 * @param prefix A string to prefix the output with; if NULL, then a default
724 * message prefix will be provided
726 void ModelExecution::print_infeasibility(const char *prefix) const
730 if (priv->bad_synchronization)
731 ptr += sprintf(ptr, "[bad sw ordering]");
733 model_print("%s: %s", prefix ? prefix : "Infeasible", buf);
737 * Check if the current partial trace is infeasible. Does not check any
738 * end-of-execution flags, which might rule out the execution. Thus, this is
739 * useful only for ruling an execution as infeasible.
740 * @return whether the current partial trace is infeasible.
742 bool ModelExecution::is_infeasible() const
744 return priv->bad_synchronization;
747 /** Close out a RMWR by converting previous RMWR into a RMW or READ. */
748 ModelAction * ModelExecution::process_rmw(ModelAction *act) {
749 ModelAction *lastread = get_last_action(act->get_tid());
750 lastread->process_rmw(act);
752 mo_graph->addRMWEdge(lastread->get_reads_from(), lastread);
758 * @brief Updates the mo_graph with the constraints imposed from the current
761 * Basic idea is the following: Go through each other thread and find
762 * the last action that happened before our read. Two cases:
764 * -# The action is a write: that write must either occur before
765 * the write we read from or be the write we read from.
766 * -# The action is a read: the write that that action read from
767 * must occur before the write we read from or be the same write.
769 * @param curr The current action. Must be a read.
770 * @param rf The ModelAction or Promise that curr reads from. Must be a write.
771 * @return True if modification order edges were added; false otherwise
774 bool ModelExecution::r_modification_order(ModelAction *curr, const ModelAction *rf, SnapVector<const ModelAction *> * priorset, bool * canprune)
776 SnapVector<action_list_t> *thrd_lists = obj_thrd_map.get(curr->get_location());
778 ASSERT(curr->is_read());
780 /* Last SC fence in the current thread */
781 ModelAction *last_sc_fence_local = get_last_seq_cst_fence(curr->get_tid(), NULL);
783 int tid = curr->get_tid();
784 ModelAction *prev_same_thread = NULL;
785 /* Iterate over all threads */
786 for (i = 0;i < thrd_lists->size();i++, tid = (((unsigned int)(tid+1)) == thrd_lists->size()) ? 0 : tid + 1) {
787 /* Last SC fence in thread tid */
788 ModelAction *last_sc_fence_thread_local = NULL;
790 last_sc_fence_thread_local = get_last_seq_cst_fence(int_to_id(tid), NULL);
792 /* Last SC fence in thread tid, before last SC fence in current thread */
793 ModelAction *last_sc_fence_thread_before = NULL;
794 if (last_sc_fence_local)
795 last_sc_fence_thread_before = get_last_seq_cst_fence(int_to_id(tid), last_sc_fence_local);
797 //Only need to iterate if either hb has changed for thread in question or SC fence after last operation...
798 if (prev_same_thread != NULL &&
799 (prev_same_thread->get_cv()->getClock(tid) == curr->get_cv()->getClock(tid)) &&
800 (last_sc_fence_thread_local == NULL || *last_sc_fence_thread_local < *prev_same_thread)) {
804 /* Iterate over actions in thread, starting from most recent */
805 action_list_t *list = &(*thrd_lists)[tid];
806 action_list_t::reverse_iterator rit;
807 for (rit = list->rbegin();rit != list->rend();rit++) {
808 ModelAction *act = *rit;
813 /* Don't want to add reflexive edges on 'rf' */
814 if (act->equals(rf)) {
815 if (act->happens_before(curr))
821 if (act->is_write()) {
822 /* C++, Section 29.3 statement 5 */
823 if (curr->is_seqcst() && last_sc_fence_thread_local &&
824 *act < *last_sc_fence_thread_local) {
825 if (mo_graph->checkReachable(rf, act))
827 priorset->push_back(act);
830 /* C++, Section 29.3 statement 4 */
831 else if (act->is_seqcst() && last_sc_fence_local &&
832 *act < *last_sc_fence_local) {
833 if (mo_graph->checkReachable(rf, act))
835 priorset->push_back(act);
838 /* C++, Section 29.3 statement 6 */
839 else if (last_sc_fence_thread_before &&
840 *act < *last_sc_fence_thread_before) {
841 if (mo_graph->checkReachable(rf, act))
843 priorset->push_back(act);
849 * Include at most one act per-thread that "happens
852 if (act->happens_before(curr)) {
854 if (last_sc_fence_local == NULL ||
855 (*last_sc_fence_local < *act)) {
856 prev_same_thread = act;
859 if (act->is_write()) {
860 if (mo_graph->checkReachable(rf, act))
862 priorset->push_back(act);
864 const ModelAction *prevrf = act->get_reads_from();
865 if (!prevrf->equals(rf)) {
866 if (mo_graph->checkReachable(rf, prevrf))
868 priorset->push_back(prevrf);
870 if (act->get_tid() == curr->get_tid()) {
871 //Can prune curr from obj list
884 * Updates the mo_graph with the constraints imposed from the current write.
886 * Basic idea is the following: Go through each other thread and find
887 * the lastest action that happened before our write. Two cases:
889 * (1) The action is a write => that write must occur before
892 * (2) The action is a read => the write that that action read from
893 * must occur before the current write.
895 * This method also handles two other issues:
897 * (I) Sequential Consistency: Making sure that if the current write is
898 * seq_cst, that it occurs after the previous seq_cst write.
900 * (II) Sending the write back to non-synchronizing reads.
902 * @param curr The current action. Must be a write.
903 * @param send_fv A vector for stashing reads to which we may pass our future
904 * value. If NULL, then don't record any future values.
905 * @return True if modification order edges were added; false otherwise
907 void ModelExecution::w_modification_order(ModelAction *curr)
909 SnapVector<action_list_t> *thrd_lists = obj_thrd_map.get(curr->get_location());
911 ASSERT(curr->is_write());
913 SnapList<ModelAction *> edgeset;
915 if (curr->is_seqcst()) {
916 /* We have to at least see the last sequentially consistent write,
917 so we are initialized. */
918 ModelAction *last_seq_cst = get_last_seq_cst_write(curr);
919 if (last_seq_cst != NULL) {
920 edgeset.push_back(last_seq_cst);
924 /* Last SC fence in the current thread */
925 ModelAction *last_sc_fence_local = get_last_seq_cst_fence(curr->get_tid(), NULL);
927 /* Iterate over all threads */
928 for (i = 0;i < thrd_lists->size();i++) {
929 /* Last SC fence in thread i, before last SC fence in current thread */
930 ModelAction *last_sc_fence_thread_before = NULL;
931 if (last_sc_fence_local && int_to_id((int)i) != curr->get_tid())
932 last_sc_fence_thread_before = get_last_seq_cst_fence(int_to_id(i), last_sc_fence_local);
934 /* Iterate over actions in thread, starting from most recent */
935 action_list_t *list = &(*thrd_lists)[i];
936 action_list_t::reverse_iterator rit;
937 for (rit = list->rbegin();rit != list->rend();rit++) {
938 ModelAction *act = *rit;
941 * 1) If RMW and it actually read from something, then we
942 * already have all relevant edges, so just skip to next
945 * 2) If RMW and it didn't read from anything, we should
946 * whatever edge we can get to speed up convergence.
948 * 3) If normal write, we need to look at earlier actions, so
949 * continue processing list.
951 if (curr->is_rmw()) {
952 if (curr->get_reads_from() != NULL)
960 /* C++, Section 29.3 statement 7 */
961 if (last_sc_fence_thread_before && act->is_write() &&
962 *act < *last_sc_fence_thread_before) {
963 edgeset.push_back(act);
968 * Include at most one act per-thread that "happens
971 if (act->happens_before(curr)) {
973 * Note: if act is RMW, just add edge:
975 * The following edge should be handled elsewhere:
976 * readfrom(act) --mo--> act
979 edgeset.push_back(act);
980 else if (act->is_read()) {
981 //if previous read accessed a null, just keep going
982 edgeset.push_back(act);
988 mo_graph->addEdges(&edgeset, curr);
993 * Arbitrary reads from the future are not allowed. Section 29.3 part 9 places
994 * some constraints. This method checks one the following constraint (others
995 * require compiler support):
997 * If X --hb-> Y --mo-> Z, then X should not read from Z.
998 * If X --hb-> Y, A --rf-> Y, and A --mo-> Z, then X should not read from Z.
1000 bool ModelExecution::mo_may_allow(const ModelAction *writer, const ModelAction *reader)
1002 SnapVector<action_list_t> *thrd_lists = obj_thrd_map.get(reader->get_location());
1004 /* Iterate over all threads */
1005 for (i = 0;i < thrd_lists->size();i++) {
1006 const ModelAction *write_after_read = NULL;
1008 /* Iterate over actions in thread, starting from most recent */
1009 action_list_t *list = &(*thrd_lists)[i];
1010 action_list_t::reverse_iterator rit;
1011 for (rit = list->rbegin();rit != list->rend();rit++) {
1012 ModelAction *act = *rit;
1014 /* Don't disallow due to act == reader */
1015 if (!reader->happens_before(act) || reader == act)
1017 else if (act->is_write())
1018 write_after_read = act;
1019 else if (act->is_read() && act->get_reads_from() != NULL)
1020 write_after_read = act->get_reads_from();
1023 if (write_after_read && write_after_read != writer && mo_graph->checkReachable(write_after_read, writer))
1030 * Computes the clock vector that happens before propagates from this write.
1032 * @param rf The action that might be part of a release sequence. Must be a
1034 * @return ClockVector of happens before relation.
1037 ClockVector * ModelExecution::get_hb_from_write(ModelAction *rf) const {
1038 SnapVector<ModelAction *> * processset = NULL;
1039 for ( ;rf != NULL;rf = rf->get_reads_from()) {
1040 ASSERT(rf->is_write());
1041 if (!rf->is_rmw() || (rf->is_acquire() && rf->is_release()) || rf->get_rfcv() != NULL)
1043 if (processset == NULL)
1044 processset = new SnapVector<ModelAction *>();
1045 processset->push_back(rf);
1048 int i = (processset == NULL) ? 0 : processset->size();
1050 ClockVector * vec = NULL;
1052 if (rf->get_rfcv() != NULL) {
1053 vec = rf->get_rfcv();
1054 } else if (rf->is_acquire() && rf->is_release()) {
1056 } else if (rf->is_release() && !rf->is_rmw()) {
1058 } else if (rf->is_release()) {
1059 //have rmw that is release and doesn't have a rfcv
1060 (vec = new ClockVector(vec, NULL))->merge(rf->get_cv());
1063 //operation that isn't release
1064 if (rf->get_last_fence_release()) {
1066 vec = rf->get_last_fence_release()->get_cv();
1068 (vec=new ClockVector(vec, NULL))->merge(rf->get_last_fence_release()->get_cv());
1074 rf = (*processset)[i];
1078 if (processset != NULL)
1084 * Performs various bookkeeping operations for the current ModelAction. For
1085 * instance, adds action to the per-object, per-thread action vector and to the
1086 * action trace list of all thread actions.
1088 * @param act is the ModelAction to add.
1090 void ModelExecution::add_action_to_lists(ModelAction *act)
1092 int tid = id_to_int(act->get_tid());
1093 ModelAction *uninit = NULL;
1095 action_list_t *list = get_safe_ptr_action(&obj_map, act->get_location());
1096 if (list->empty() && act->is_atomic_var()) {
1097 uninit = get_uninitialized_action(act);
1098 uninit_id = id_to_int(uninit->get_tid());
1099 list->push_front(uninit);
1100 SnapVector<action_list_t> *vec = get_safe_ptr_vect_action(&obj_wr_thrd_map, act->get_location());
1101 if (uninit_id >= (int)vec->size())
1102 vec->resize(uninit_id + 1);
1103 (*vec)[uninit_id].push_front(uninit);
1105 list->push_back(act);
1107 // Update action trace, a total order of all actions
1108 action_trace.push_back(act);
1110 action_trace.push_front(uninit);
1112 // Update obj_thrd_map, a per location, per thread, order of actions
1113 SnapVector<action_list_t> *vec = get_safe_ptr_vect_action(&obj_thrd_map, act->get_location());
1114 if (tid >= (int)vec->size())
1115 vec->resize(priv->next_thread_id);
1116 (*vec)[tid].push_back(act);
1118 (*vec)[uninit_id].push_front(uninit);
1120 // Update thrd_last_action, the last action taken by each thrad
1121 if ((int)thrd_last_action.size() <= tid)
1122 thrd_last_action.resize(get_num_threads());
1123 thrd_last_action[tid] = act;
1125 thrd_last_action[uninit_id] = uninit;
1127 // Update thrd_last_fence_release, the last release fence taken by each thread
1128 if (act->is_fence() && act->is_release()) {
1129 if ((int)thrd_last_fence_release.size() <= tid)
1130 thrd_last_fence_release.resize(get_num_threads());
1131 thrd_last_fence_release[tid] = act;
1134 if (act->is_wait()) {
1135 void *mutex_loc = (void *) act->get_value();
1136 get_safe_ptr_action(&obj_map, mutex_loc)->push_back(act);
1138 SnapVector<action_list_t> *vec = get_safe_ptr_vect_action(&obj_thrd_map, mutex_loc);
1139 if (tid >= (int)vec->size())
1140 vec->resize(priv->next_thread_id);
1141 (*vec)[tid].push_back(act);
1145 void insertIntoActionList(action_list_t *list, ModelAction *act) {
1146 action_list_t::reverse_iterator rit = list->rbegin();
1147 modelclock_t next_seq = act->get_seq_number();
1148 if (rit == list->rend() || (*rit)->get_seq_number() == next_seq)
1149 list->push_back(act);
1151 for(;rit != list->rend();rit++) {
1152 if ((*rit)->get_seq_number() == next_seq) {
1153 action_list_t::iterator it = rit.base();
1154 list->insert(it, act);
1161 void insertIntoActionListAndSetCV(action_list_t *list, ModelAction *act) {
1162 action_list_t::reverse_iterator rit = list->rbegin();
1163 modelclock_t next_seq = act->get_seq_number();
1164 if (rit == list->rend()) {
1165 act->create_cv(NULL);
1166 } else if ((*rit)->get_seq_number() == next_seq) {
1167 act->create_cv((*rit));
1168 list->push_back(act);
1170 for(;rit != list->rend();rit++) {
1171 if ((*rit)->get_seq_number() == next_seq) {
1172 act->create_cv((*rit));
1173 action_list_t::iterator it = rit.base();
1174 list->insert(it, act);
1182 * Performs various bookkeeping operations for a normal write. The
1183 * complication is that we are typically inserting a normal write
1184 * lazily, so we need to insert it into the middle of lists.
1186 * @param act is the ModelAction to add.
1189 void ModelExecution::add_normal_write_to_lists(ModelAction *act)
1191 int tid = id_to_int(act->get_tid());
1192 insertIntoActionListAndSetCV(&action_trace, act);
1194 action_list_t *list = get_safe_ptr_action(&obj_map, act->get_location());
1195 insertIntoActionList(list, act);
1197 // Update obj_thrd_map, a per location, per thread, order of actions
1198 SnapVector<action_list_t> *vec = get_safe_ptr_vect_action(&obj_thrd_map, act->get_location());
1199 if (tid >= (int)vec->size())
1200 vec->resize(priv->next_thread_id);
1201 insertIntoActionList(&(*vec)[tid],act);
1203 // Update thrd_last_action, the last action taken by each thrad
1204 if (thrd_last_action[tid]->get_seq_number() == act->get_seq_number())
1205 thrd_last_action[tid] = act;
1209 void ModelExecution::add_write_to_lists(ModelAction *write) {
1210 // Update seq_cst map
1211 if (write->is_seqcst())
1212 obj_last_sc_map.put(write->get_location(), write);
1214 SnapVector<action_list_t> *vec = get_safe_ptr_vect_action(&obj_wr_thrd_map, write->get_location());
1215 int tid = id_to_int(write->get_tid());
1216 if (tid >= (int)vec->size())
1217 vec->resize(priv->next_thread_id);
1218 (*vec)[tid].push_back(write);
1222 * @brief Get the last action performed by a particular Thread
1223 * @param tid The thread ID of the Thread in question
1224 * @return The last action in the thread
1226 ModelAction * ModelExecution::get_last_action(thread_id_t tid) const
1228 int threadid = id_to_int(tid);
1229 if (threadid < (int)thrd_last_action.size())
1230 return thrd_last_action[id_to_int(tid)];
1236 * @brief Get the last fence release performed by a particular Thread
1237 * @param tid The thread ID of the Thread in question
1238 * @return The last fence release in the thread, if one exists; NULL otherwise
1240 ModelAction * ModelExecution::get_last_fence_release(thread_id_t tid) const
1242 int threadid = id_to_int(tid);
1243 if (threadid < (int)thrd_last_fence_release.size())
1244 return thrd_last_fence_release[id_to_int(tid)];
1250 * Gets the last memory_order_seq_cst write (in the total global sequence)
1251 * performed on a particular object (i.e., memory location), not including the
1253 * @param curr The current ModelAction; also denotes the object location to
1255 * @return The last seq_cst write
1257 ModelAction * ModelExecution::get_last_seq_cst_write(ModelAction *curr) const
1259 void *location = curr->get_location();
1260 return obj_last_sc_map.get(location);
1264 * Gets the last memory_order_seq_cst fence (in the total global sequence)
1265 * performed in a particular thread, prior to a particular fence.
1266 * @param tid The ID of the thread to check
1267 * @param before_fence The fence from which to begin the search; if NULL, then
1268 * search for the most recent fence in the thread.
1269 * @return The last prior seq_cst fence in the thread, if exists; otherwise, NULL
1271 ModelAction * ModelExecution::get_last_seq_cst_fence(thread_id_t tid, const ModelAction *before_fence) const
1273 /* All fences should have location FENCE_LOCATION */
1274 action_list_t *list = obj_map.get(FENCE_LOCATION);
1279 action_list_t::reverse_iterator rit = list->rbegin();
1282 for (;rit != list->rend();rit++)
1283 if (*rit == before_fence)
1286 ASSERT(*rit == before_fence);
1290 for (;rit != list->rend();rit++)
1291 if ((*rit)->is_fence() && (tid == (*rit)->get_tid()) && (*rit)->is_seqcst())
1297 * Gets the last unlock operation performed on a particular mutex (i.e., memory
1298 * location). This function identifies the mutex according to the current
1299 * action, which is presumed to perform on the same mutex.
1300 * @param curr The current ModelAction; also denotes the object location to
1302 * @return The last unlock operation
1304 ModelAction * ModelExecution::get_last_unlock(ModelAction *curr) const
1306 void *location = curr->get_location();
1308 action_list_t *list = obj_map.get(location);
1309 /* Find: max({i in dom(S) | isUnlock(t_i) && samevar(t_i, t)}) */
1310 action_list_t::reverse_iterator rit;
1311 for (rit = list->rbegin();rit != list->rend();rit++)
1312 if ((*rit)->is_unlock() || (*rit)->is_wait())
1317 ModelAction * ModelExecution::get_parent_action(thread_id_t tid) const
1319 ModelAction *parent = get_last_action(tid);
1321 parent = get_thread(tid)->get_creation();
1326 * Returns the clock vector for a given thread.
1327 * @param tid The thread whose clock vector we want
1328 * @return Desired clock vector
1330 ClockVector * ModelExecution::get_cv(thread_id_t tid) const
1332 ModelAction *firstaction=get_parent_action(tid);
1333 return firstaction != NULL ? firstaction->get_cv() : NULL;
1336 bool valequals(uint64_t val1, uint64_t val2, int size) {
1339 return ((uint8_t)val1) == ((uint8_t)val2);
1341 return ((uint16_t)val1) == ((uint16_t)val2);
1343 return ((uint32_t)val1) == ((uint32_t)val2);
1353 * Build up an initial set of all past writes that this 'read' action may read
1354 * from, as well as any previously-observed future values that must still be valid.
1356 * @param curr is the current ModelAction that we are exploring; it must be a
1359 SnapVector<ModelAction *> * ModelExecution::build_may_read_from(ModelAction *curr)
1361 SnapVector<action_list_t> *thrd_lists = obj_wr_thrd_map.get(curr->get_location());
1363 ASSERT(curr->is_read());
1365 ModelAction *last_sc_write = NULL;
1367 if (curr->is_seqcst())
1368 last_sc_write = get_last_seq_cst_write(curr);
1370 SnapVector<ModelAction *> * rf_set = new SnapVector<ModelAction *>();
1372 /* Iterate over all threads */
1373 for (i = 0;i < thrd_lists->size();i++) {
1374 /* Iterate over actions in thread, starting from most recent */
1375 action_list_t *list = &(*thrd_lists)[i];
1376 action_list_t::reverse_iterator rit;
1377 for (rit = list->rbegin();rit != list->rend();rit++) {
1378 ModelAction *act = *rit;
1383 /* Don't consider more than one seq_cst write if we are a seq_cst read. */
1384 bool allow_read = true;
1386 if (curr->is_seqcst() && (act->is_seqcst() || (last_sc_write != NULL && act->happens_before(last_sc_write))) && act != last_sc_write)
1389 /* Need to check whether we will have two RMW reading from the same value */
1390 if (curr->is_rmwr()) {
1391 /* It is okay if we have a failing CAS */
1392 if (!curr->is_rmwrcas() ||
1393 valequals(curr->get_value(), act->get_value(), curr->getSize())) {
1394 //Need to make sure we aren't the second RMW
1395 CycleNode * node = mo_graph->getNode_noCreate(act);
1396 if (node != NULL && node->getRMW() != NULL) {
1397 //we are the second RMW
1404 /* Only add feasible reads */
1405 rf_set->push_back(act);
1408 /* Include at most one act per-thread that "happens before" curr */
1409 if (act->happens_before(curr))
1414 if (DBG_ENABLED()) {
1415 model_print("Reached read action:\n");
1417 model_print("End printing read_from_past\n");
1423 * @brief Get an action representing an uninitialized atomic
1425 * This function may create a new one.
1427 * @param curr The current action, which prompts the creation of an UNINIT action
1428 * @return A pointer to the UNINIT ModelAction
1430 ModelAction * ModelExecution::get_uninitialized_action(ModelAction *curr) const
1432 ModelAction *act = curr->get_uninit_action();
1434 act = new ModelAction(ATOMIC_UNINIT, std::memory_order_relaxed, curr->get_location(), params->uninitvalue, model_thread);
1435 curr->set_uninit_action(act);
1437 act->create_cv(NULL);
1441 static void print_list(const action_list_t *list)
1443 action_list_t::const_iterator it;
1445 model_print("------------------------------------------------------------------------------------\n");
1446 model_print("# t Action type MO Location Value Rf CV\n");
1447 model_print("------------------------------------------------------------------------------------\n");
1449 unsigned int hash = 0;
1451 for (it = list->begin();it != list->end();it++) {
1452 const ModelAction *act = *it;
1453 if (act->get_seq_number() > 0)
1455 hash = hash^(hash<<3)^((*it)->hash());
1457 model_print("HASH %u\n", hash);
1458 model_print("------------------------------------------------------------------------------------\n");
1461 #if SUPPORT_MOD_ORDER_DUMP
1462 void ModelExecution::dumpGraph(char *filename) const
1465 sprintf(buffer, "%s.dot", filename);
1466 FILE *file = fopen(buffer, "w");
1467 fprintf(file, "digraph %s {\n", filename);
1468 mo_graph->dumpNodes(file);
1469 ModelAction **thread_array = (ModelAction **)model_calloc(1, sizeof(ModelAction *) * get_num_threads());
1471 for (action_list_t::const_iterator it = action_trace.begin();it != action_trace.end();it++) {
1472 ModelAction *act = *it;
1473 if (act->is_read()) {
1474 mo_graph->dot_print_node(file, act);
1475 mo_graph->dot_print_edge(file,
1476 act->get_reads_from(),
1478 "label=\"rf\", color=red, weight=2");
1480 if (thread_array[act->get_tid()]) {
1481 mo_graph->dot_print_edge(file,
1482 thread_array[id_to_int(act->get_tid())],
1484 "label=\"sb\", color=blue, weight=400");
1487 thread_array[act->get_tid()] = act;
1489 fprintf(file, "}\n");
1490 model_free(thread_array);
1495 /** @brief Prints an execution trace summary. */
1496 void ModelExecution::print_summary() const
1498 #if SUPPORT_MOD_ORDER_DUMP
1499 char buffername[100];
1500 sprintf(buffername, "exec%04u", get_execution_number());
1501 mo_graph->dumpGraphToFile(buffername);
1502 sprintf(buffername, "graph%04u", get_execution_number());
1503 dumpGraph(buffername);
1506 model_print("Execution trace %d:", get_execution_number());
1507 if (isfeasibleprefix()) {
1508 if (scheduler->all_threads_sleeping())
1509 model_print(" SLEEP-SET REDUNDANT");
1510 if (have_bug_reports())
1511 model_print(" DETECTED BUG(S)");
1513 print_infeasibility(" INFEASIBLE");
1516 print_list(&action_trace);
1522 * Add a Thread to the system for the first time. Should only be called once
1524 * @param t The Thread to add
1526 void ModelExecution::add_thread(Thread *t)
1528 unsigned int i = id_to_int(t->get_id());
1529 if (i >= thread_map.size())
1530 thread_map.resize(i + 1);
1532 if (!t->is_model_thread())
1533 scheduler->add_thread(t);
1537 * @brief Get a Thread reference by its ID
1538 * @param tid The Thread's ID
1539 * @return A Thread reference
1541 Thread * ModelExecution::get_thread(thread_id_t tid) const
1543 unsigned int i = id_to_int(tid);
1544 if (i < thread_map.size())
1545 return thread_map[i];
1550 * @brief Get a reference to the Thread in which a ModelAction was executed
1551 * @param act The ModelAction
1552 * @return A Thread reference
1554 Thread * ModelExecution::get_thread(const ModelAction *act) const
1556 return get_thread(act->get_tid());
1560 * @brief Get a Thread reference by its pthread ID
1561 * @param index The pthread's ID
1562 * @return A Thread reference
1564 Thread * ModelExecution::get_pthread(pthread_t pid) {
1570 uint32_t thread_id = x.v;
1571 if (thread_id < pthread_counter + 1) return pthread_map[thread_id];
1576 * @brief Check if a Thread is currently enabled
1577 * @param t The Thread to check
1578 * @return True if the Thread is currently enabled
1580 bool ModelExecution::is_enabled(Thread *t) const
1582 return scheduler->is_enabled(t);
1586 * @brief Check if a Thread is currently enabled
1587 * @param tid The ID of the Thread to check
1588 * @return True if the Thread is currently enabled
1590 bool ModelExecution::is_enabled(thread_id_t tid) const
1592 return scheduler->is_enabled(tid);
1596 * @brief Select the next thread to execute based on the curren action
1598 * RMW actions occur in two parts, and we cannot split them. And THREAD_CREATE
1599 * actions should be followed by the execution of their child thread. In either
1600 * case, the current action should determine the next thread schedule.
1602 * @param curr The current action
1603 * @return The next thread to run, if the current action will determine this
1604 * selection; otherwise NULL
1606 Thread * ModelExecution::action_select_next_thread(const ModelAction *curr) const
1608 /* Do not split atomic RMW */
1609 if (curr->is_rmwr())
1610 return get_thread(curr);
1611 /* Follow CREATE with the created thread */
1612 /* which is not needed, because model.cc takes care of this */
1613 if (curr->get_type() == THREAD_CREATE)
1614 return curr->get_thread_operand();
1615 if (curr->get_type() == PTHREAD_CREATE) {
1616 return curr->get_thread_operand();
1622 * Takes the next step in the execution, if possible.
1623 * @param curr The current step to take
1624 * @return Returns the next Thread to run, if any; NULL if this execution
1627 Thread * ModelExecution::take_step(ModelAction *curr)
1629 Thread *curr_thrd = get_thread(curr);
1630 ASSERT(curr_thrd->get_state() == THREAD_READY);
1632 ASSERT(check_action_enabled(curr)); /* May have side effects? */
1633 curr = check_current_action(curr);
1636 /* Process this action in ModelHistory for records*/
1637 model->get_history()->process_action( curr, curr_thrd->get_id() );
1639 if (curr_thrd->is_blocked() || curr_thrd->is_complete())
1640 scheduler->remove_thread(curr_thrd);
1642 return action_select_next_thread(curr);
1645 Fuzzer * ModelExecution::getFuzzer() {