X-Git-Url: http://plrg.eecs.uci.edu/git/?p=model-checker.git;a=blobdiff_plain;f=model.cc;h=fb492a5363d1cfea467d3a8ef1438c812fd11e83;hp=1712a60a9dd3990efeef26f257467f5bff7d6bb0;hb=fff0a7571d2fc4b9c3186ae2c7f844c22dac3b2b;hpb=e309adaee27786a638bcd44303ecb88351074257 diff --git a/model.cc b/model.cc index 1712a60..fb492a5 100644 --- a/model.cc +++ b/model.cc @@ -21,6 +21,7 @@ ModelChecker::ModelChecker(struct model_params params) : /* Initialize default scheduler */ scheduler(new Scheduler()), num_executions(0), + num_feasible_executions(0), params(params), diverge(NULL), action_trace(new action_list_t()), @@ -174,6 +175,8 @@ bool ModelChecker::next_execution() DBG(); num_executions++; + if (isfinalfeasible()) + num_feasible_executions++; if (isfinalfeasible() || DBG_ENABLED()) print_summary(); @@ -194,21 +197,33 @@ ModelAction * ModelChecker::get_last_conflict(ModelAction *act) { action_type type = act->get_type(); - switch (type) { - case ATOMIC_READ: - case ATOMIC_WRITE: - case ATOMIC_RMW: - break; - default: - return NULL; - } - /* linear search: from most recent to oldest */ - action_list_t *list = obj_map->get_safe_ptr(act->get_location()); - action_list_t::reverse_iterator rit; - for (rit = list->rbegin(); rit != list->rend(); rit++) { - ModelAction *prev = *rit; - if (act->is_synchronizing(prev)) - return prev; + if (type==ATOMIC_READ||type==ATOMIC_WRITE||type==ATOMIC_RMW) { + /* linear search: from most recent to oldest */ + action_list_t *list = obj_map->get_safe_ptr(act->get_location()); + action_list_t::reverse_iterator rit; + for (rit = list->rbegin(); rit != list->rend(); rit++) { + ModelAction *prev = *rit; + if (act->is_synchronizing(prev)) + return prev; + } + } else if (type==ATOMIC_LOCK||type==ATOMIC_TRYLOCK) { + /* linear search: from most recent to oldest */ + action_list_t *list = obj_map->get_safe_ptr(act->get_location()); + action_list_t::reverse_iterator rit; + for (rit = list->rbegin(); rit != list->rend(); rit++) { + ModelAction *prev = *rit; + if (prev->is_success_lock()) + return prev; + } + } else if (type==ATOMIC_UNLOCK) { + /* linear search: from most recent to oldest */ + action_list_t *list = obj_map->get_safe_ptr(act->get_location()); + action_list_t::reverse_iterator rit; + for (rit = list->rbegin(); rit != list->rend(); rit++) { + ModelAction *prev = *rit; + if (prev->is_failed_trylock()) + return prev; + } } return NULL; } @@ -262,11 +277,11 @@ ModelAction * ModelChecker::get_next_backtrack() /** * Processes a read or rmw model action. * @param curr is the read model action to process. - * @param th is the thread * @param second_part_of_rmw is boolean that is true is this is the second action of a rmw. * @return True if processing this read updates the mo_graph. */ -bool ModelChecker::process_read(ModelAction *curr, Thread * th, bool second_part_of_rmw) { +bool ModelChecker::process_read(ModelAction *curr, bool second_part_of_rmw) +{ uint64_t value; bool updated = false; while (true) { @@ -300,11 +315,36 @@ bool ModelChecker::process_read(ModelAction *curr, Thread * th, bool second_part Promise *valuepromise = new Promise(curr, value, expiration); promises->push_back(valuepromise); } - th->set_return_value(value); + get_thread(curr)->set_return_value(value); return updated; } } +/** + * Process a write ModelAction + * @param curr The ModelAction to process + * @return True if the mo_graph was updated or promises were resolved + */ +bool ModelChecker::process_write(ModelAction *curr) +{ + bool updated_mod_order = w_modification_order(curr); + bool updated_promises = resolve_promises(curr); + + if (promises->size() == 0) { + for (unsigned int i = 0; isize(); i++) { + struct PendingFutureValue pfv = (*futurevalues)[i]; + if (pfv.act->get_node()->add_future_value(pfv.value, pfv.expiration) && + (!priv->next_backtrack || *pfv.act > *priv->next_backtrack)) + priv->next_backtrack = pfv.act; + } + futurevalues->resize(0); + } + + mo_graph->commitChanges(); + get_thread(curr)->set_return_value(VALUE_NONE); + return updated_mod_order || updated_promises; +} + /** * This is the heart of the model checker routine. It performs model-checking * actions corresponding to a given "current action." Among other processes, it @@ -330,16 +370,18 @@ Thread * ModelChecker::check_current_action(ModelAction *curr) curr = tmp; compute_promises(curr); } else { - ModelAction *tmp = node_stack->explore_action(curr); + ModelAction *tmp = node_stack->explore_action(curr, scheduler->get_enabled()); if (tmp) { /* Discard duplicate ModelAction; use action from NodeStack */ /* First restore type and order in case of RMW operation */ if (curr->is_rmwr()) tmp->copy_typeandorder(curr); - + /* If we have diverged, we need to reset the clock vector. */ if (diverge == NULL) tmp->create_cv(get_parent_action(tmp->get_tid())); + + ASSERT(curr->get_location()==tmp->get_location()); delete curr; curr = tmp; @@ -392,33 +434,36 @@ Thread * ModelChecker::check_current_action(ModelAction *curr) break; } - bool updated = false; + work_queue_t work_queue(1, CheckCurrWorkEntry(curr)); - if (curr->is_read()) { - updated = process_read(curr, get_thread(curr), second_part_of_rmw); - } + while (!work_queue.empty()) { + WorkQueueEntry work = work_queue.front(); + work_queue.pop_front(); - if (curr->is_write()) { - bool updated_mod_order = w_modification_order(curr); - bool updated_promises = resolve_promises(curr); - updated = updated || updated_mod_order || updated_promises; - - if (promises->size()==0) { - for (unsigned int i = 0; isize(); i++) { - struct PendingFutureValue pfv=(*futurevalues)[i]; - if (pfv.act->get_node()->add_future_value(pfv.value, pfv.expiration) && - (!priv->next_backtrack || *pfv.act > *priv->next_backtrack)) - priv->next_backtrack = pfv.act; - } - futurevalues->resize(0); - } + switch (work.type) { + case WORK_CHECK_CURR_ACTION: { + ModelAction *act = work.action; + bool updated = false; + if (act->is_read() && process_read(act, second_part_of_rmw)) + updated = true; - mo_graph->commitChanges(); - get_thread(curr)->set_return_value(VALUE_NONE); - } + if (act->is_write() && process_write(act)) + updated = true; - if (updated) - resolve_release_sequences(curr->get_location()); + if (updated) + work_queue.push_back(CheckRelSeqWorkEntry(act->get_location())); + break; + } + case WORK_CHECK_RELEASE_SEQ: + resolve_release_sequences(work.location, &work_queue); + break; + case WORK_CHECK_MO_EDGES: + /** @todo Perform follow-up mo_graph checks */ + default: + ASSERT(false); + break; + } + } /* Add action to list. */ if (!second_part_of_rmw) @@ -586,7 +631,18 @@ void ModelChecker::check_recency(ModelAction *curr, bool already_added) { } /** - * Updates the mo_graph with the constraints imposed from the current read. + * Updates the mo_graph with the constraints imposed from the current + * read. + * + * Basic idea is the following: Go through each other thread and find + * the lastest action that happened before our read. Two cases: + * + * (1) The action is a write => that write must either occur before + * the write we read from or be the write we read from. + * + * (2) The action is a read => the write that that action read from + * must occur before the write we read from or be the same write. + * * @param curr The current action. Must be a read. * @param rf The action that curr reads from. Must be a write. * @return True if modification order edges were added; false otherwise @@ -629,7 +685,22 @@ bool ModelChecker::r_modification_order(ModelAction *curr, const ModelAction *rf return added; } -/** Updates the mo_graph with the constraints imposed from the current read. */ +/** This method fixes up the modification order when we resolve a + * promises. The basic problem is that actions that occur after the + * read curr could not property add items to the modification order + * for our read. + * + * So for each thread, we find the earliest item that happens after + * the read curr. This is the item we have to fix up with additional + * constraints. If that action is write, we add a MO edge between + * the Action rf and that action. If the action is a read, we add a + * MO edge between the Action rf, and whatever the read accessed. + * + * @param curr is the read ModelAction that we are fixing up MO edges for. + * @param rf is the write ModelAction that curr reads from. + * + */ + void ModelChecker::post_r_modification_order(ModelAction *curr, const ModelAction *rf) { std::vector *thrd_lists = obj_thrd_map->get_safe_ptr(curr->get_location()); @@ -668,6 +739,23 @@ void ModelChecker::post_r_modification_order(ModelAction *curr, const ModelActio /** * Updates the mo_graph with the constraints imposed from the current write. + * + * Basic idea is the following: Go through each other thread and find + * the lastest action that happened before our write. Two cases: + * + * (1) The action is a write => that write must occur before + * the current write + * + * (2) The action is a read => the write that that action read from + * must occur before the current write. + * + * This method also handles two other issues: + * + * (I) Sequential Consistency: Making sure that if the current write is + * seq_cst, that it occurs after the previous seq_cst write. + * + * (II) Sending the write back to non-synchronizing reads. + * * @param curr The current action. Must be a write. * @return True if modification order edges were added; false otherwise */ @@ -908,9 +996,12 @@ void ModelChecker::get_release_seq_heads(ModelAction *act, * * @param location The location/object that should be checked for release * sequence resolutions - * @return True if any updates occurred (new synchronization, new mo_graph edges) + * @param work_queue The work queue to which to add work items as they are + * generated + * @return True if any updates occurred (new synchronization, new mo_graph + * edges) */ -bool ModelChecker::resolve_release_sequences(void *location) +bool ModelChecker::resolve_release_sequences(void *location, work_queue_t *work_queue) { std::list *list; list = lazy_sync_with_release->getptr(location); @@ -933,14 +1024,18 @@ bool ModelChecker::resolve_release_sequences(void *location) } if (updated) { + /* Re-check act for mo_graph edges */ + work_queue->push_back(MOEdgeWorkEntry(act)); + /* propagate synchronization to later actions */ action_list_t::reverse_iterator it = action_trace->rbegin(); while ((*it) != act) { ModelAction *propagate = *it; - if (act->happens_before(propagate)) - /** @todo new mo_graph edges along with - * this synchronization? */ + if (act->happens_before(propagate)) { propagate->synchronize_with(act); + /* Re-check 'propagate' for mo_graph edges */ + work_queue->push_back(MOEdgeWorkEntry(propagate)); + } } } if (complete) { @@ -984,10 +1079,11 @@ void ModelChecker::add_action_to_lists(ModelAction *act) ModelAction * ModelChecker::get_last_action(thread_id_t tid) { - int nthreads = get_num_threads(); - if ((int)thrd_last_action->size() < nthreads) - thrd_last_action->resize(nthreads); - return (*thrd_last_action)[id_to_int(tid)]; + int threadid=id_to_int(tid); + if (threadid<(int)thrd_last_action->size()) + return (*thrd_last_action)[id_to_int(tid)]; + else + return NULL; } /** @@ -1043,7 +1139,11 @@ bool ModelChecker::resolve_promises(ModelAction *write) if (read->is_rmw()) { mo_graph->addRMWEdge(write, read); } + //First fix up the modification order for actions that happened + //before the read r_modification_order(read, write); + //Next fix up the modification order for actions that happened + //after the read. post_r_modification_order(read, write); promises->erase(promises->begin() + promise_index); resolved = true; @@ -1182,6 +1282,7 @@ void ModelChecker::print_summary() { printf("\n"); printf("Number of executions: %d\n", num_executions); + printf("Number of feasible executions: %d\n", num_feasible_executions); printf("Total nodes created: %d\n", node_stack->get_total_nodes()); #if SUPPORT_MOD_ORDER_DUMP @@ -1235,25 +1336,23 @@ int ModelChecker::switch_to_master(ModelAction *act) * @return Returns true (success) if a step was taken and false otherwise. */ bool ModelChecker::take_step() { - Thread *curr, *next; - if (has_asserted()) return false; - curr = thread_current(); + Thread * curr = thread_current(); if (curr) { if (curr->get_state() == THREAD_READY) { ASSERT(priv->current_action); priv->nextThread = check_current_action(priv->current_action); priv->current_action = NULL; - if (!curr->is_blocked() && !curr->is_complete()) - scheduler->add_thread(curr); + if (curr->is_blocked() || curr->is_complete()) + scheduler->remove_thread(curr); } else { ASSERT(false); } } - next = scheduler->next_thread(priv->nextThread); + Thread * next = scheduler->next_thread(priv->nextThread); /* Infeasible -> don't take any more steps */ if (!isfeasible())