X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=model.cc;h=5625f30ca8b637e362ebe49203394e52fe9d9e11;hb=7d48344a260daccd4a4255bd7e07ab232c7ba653;hp=326358ea79c8b80ed0a356854cef43288c0ec304;hpb=cf4cc8a444d3c85367b9aa15b91b2829220e2edf;p=model-checker.git diff --git a/model.cc b/model.cc index 326358e..5625f30 100644 --- a/model.cc +++ b/model.cc @@ -1,5 +1,7 @@ #include #include +#include +#include #include "model.h" #include "action.h" @@ -7,14 +9,12 @@ #include "schedule.h" #include "snapshot-interface.h" #include "common.h" -#include "clockvector.h" -#include "cyclegraph.h" -#include "promise.h" #include "datarace.h" -#include "mutex.h" -#include "threads.h" - -#define INITIAL_THREAD_ID 0 +#include "threads-model.h" +#include "output.h" +#include "traceanalysis.h" +#include "execution.h" +#include "bugmessage.h" ModelChecker *model; @@ -23,54 +23,20 @@ ModelChecker::ModelChecker(struct model_params params) : /* Initialize default scheduler */ params(params), scheduler(new Scheduler()), - num_executions(0), - num_feasible_executions(0), + node_stack(new NodeStack()), + execution(new ModelExecution(this, &this->params, scheduler, node_stack)), + execution_number(1), diverge(NULL), earliest_diverge(NULL), - action_trace(new action_list_t()), - thread_map(new HashTable()), - obj_map(new HashTable()), - lock_waiters_map(new HashTable()), - obj_thrd_map(new HashTable, uintptr_t, 4 >()), - promises(new std::vector()), - futurevalues(new std::vector()), - pending_acq_rel_seq(new std::vector()), - thrd_last_action(new std::vector(1)), - node_stack(new NodeStack()), - mo_graph(new CycleGraph()), - failed_promise(false), - too_many_reads(false), - asserted(false), - bad_synchronization(false) + trace_analyses() { - /* Allocate this "size" on the snapshotting heap */ - priv = (struct model_snapshot_members *)calloc(1, sizeof(*priv)); - /* First thread created will have id INITIAL_THREAD_ID */ - priv->next_thread_id = INITIAL_THREAD_ID; } /** @brief Destructor */ ModelChecker::~ModelChecker() { - for (int i = 0; i < get_num_threads(); i++) - delete thread_map->get(i); - delete thread_map; - - delete obj_thrd_map; - delete obj_map; - delete lock_waiters_map; - delete action_trace; - - for (unsigned int i = 0; i < promises->size(); i++) - delete (*promises)[i]; - delete promises; - - delete pending_acq_rel_seq; - - delete thrd_last_action; delete node_stack; delete scheduler; - delete mo_graph; } /** @@ -81,97 +47,90 @@ void ModelChecker::reset_to_initial_state() { DEBUG("+++ Resetting to initial state +++\n"); node_stack->reset_execution(); - failed_promise = false; - too_many_reads = false; - bad_synchronization = false; - reset_asserted(); - snapshotObject->backTrackBeforeStep(0); -} -/** @return a thread ID for a new Thread */ -thread_id_t ModelChecker::get_next_id() -{ - return priv->next_thread_id++; + /** + * FIXME: if we utilize partial rollback, we will need to free only + * those pending actions which were NOT pending before the rollback + * point + */ + for (unsigned int i = 0; i < get_num_threads(); i++) + delete get_thread(int_to_id(i))->get_pending(); + + snapshot_backtrack_before(0); } /** @return the number of user threads created during this execution */ -int ModelChecker::get_num_threads() +unsigned int ModelChecker::get_num_threads() const { - return priv->next_thread_id; + return execution->get_num_threads(); } -/** @return The currently executing Thread. */ -Thread * ModelChecker::get_current_thread() +/** + * Must be called from user-thread context (e.g., through the global + * thread_current() interface) + * + * @return The currently executing Thread. + */ +Thread * ModelChecker::get_current_thread() const { return scheduler->get_current_thread(); } -/** @return a sequence number for a new ModelAction */ -modelclock_t ModelChecker::get_next_seq_num() -{ - return ++priv->used_sequence_numbers; -} - /** * @brief Choose the next thread to execute. * - * This function chooses the next thread that should execute. It can force the - * adjacency of read/write portions of a RMW action, force THREAD_CREATE to be - * followed by a THREAD_START, or it can enforce execution replay/backtracking. - * The model-checker may have no preference regarding the next thread (i.e., - * when exploring a new execution ordering), in which case this will return - * NULL. - * @param curr The current ModelAction. This action might guide the choice of - * next thread. - * @return The next thread to run. If the model-checker has no preference, NULL. + * This function chooses the next thread that should execute. It can enforce + * execution replay/backtracking or, if the model-checker has no preference + * regarding the next thread (i.e., when exploring a new execution ordering), + * we defer to the scheduler. + * + * @return The next chosen thread to run, if any exist. Or else if the current + * execution should terminate, return NULL. */ -Thread * ModelChecker::get_next_thread(ModelAction *curr) +Thread * ModelChecker::get_next_thread() { thread_id_t tid; - if (curr!=NULL) { - /* Do not split atomic actions. */ - if (curr->is_rmwr()) - return thread_current(); - /* The THREAD_CREATE action points to the created Thread */ - else if (curr->get_type() == THREAD_CREATE) - return (Thread *)curr->get_location(); - } - - /* Have we completed exploring the preselected path? */ + /* + * Have we completed exploring the preselected path? Then let the + * scheduler decide + */ if (diverge == NULL) - return NULL; + return scheduler->select_next_thread(node_stack->get_head()); + /* Else, we are trying to replay an execution */ ModelAction *next = node_stack->get_next()->get_action(); if (next == diverge) { if (earliest_diverge == NULL || *diverge < *earliest_diverge) - earliest_diverge=diverge; + earliest_diverge = diverge; Node *nextnode = next->get_node(); + Node *prevnode = nextnode->get_parent(); + scheduler->update_sleep_set(prevnode); + /* Reached divergence point */ - if (nextnode->increment_promise()) { - /* The next node will try to satisfy a different set of promises. */ - tid = next->get_tid(); - node_stack->pop_restofstack(2); - } else if (nextnode->increment_read_from()) { - /* The next node will read from a different value. */ - tid = next->get_tid(); - node_stack->pop_restofstack(2); - } else if (nextnode->increment_future_value()) { - /* The next node will try to read from a different future value. */ + if (nextnode->increment_behaviors()) { + /* Execute the same thread with a new behavior */ tid = next->get_tid(); node_stack->pop_restofstack(2); } else { + ASSERT(prevnode); /* Make a different thread execute for next step */ - Node *node = nextnode->get_parent(); - tid = node->get_next_backtrack(); + scheduler->add_sleep(get_thread(next->get_tid())); + tid = prevnode->get_next_backtrack(); + /* Make sure the backtracked thread isn't sleeping. */ node_stack->pop_restofstack(1); - if (diverge==earliest_diverge) { - earliest_diverge=node->get_action(); + if (diverge == earliest_diverge) { + earliest_diverge = prevnode->get_action(); } } + /* Start the round robin scheduler from this thread id */ + scheduler->set_scheduler_thread(tid); + /* The correct sleep set is in the parent node. */ + execute_sleep_set(); + DEBUG("*** Divergence point ***\n"); diverge = NULL; @@ -180,1532 +139,195 @@ Thread * ModelChecker::get_next_thread(ModelAction *curr) } DEBUG("*** ModelChecker chose next thread = %d ***\n", id_to_int(tid)); ASSERT(tid != THREAD_ID_T_NONE); - return thread_map->get(id_to_int(tid)); + return get_thread(id_to_int(tid)); } /** - * Queries the model-checker for more executions to explore and, if one - * exists, resets the model-checker state to execute a new execution. - * - * @return If there are more executions to explore, return true. Otherwise, - * return false. + * We need to know what the next actions of all threads in the sleep + * set will be. This method computes them and stores the actions at + * the corresponding thread object's pending action. */ -bool ModelChecker::next_execution() -{ - DBG(); - - num_executions++; - - if (isfinalfeasible()) { - printf("Earliest divergence point since last feasible execution:\n"); - if (earliest_diverge) - earliest_diverge->print(false); - else - printf("(Not set)\n"); - - earliest_diverge = NULL; - num_feasible_executions++; - } - - DEBUG("Number of acquires waiting on pending release sequences: %lu\n", - pending_acq_rel_seq->size()); - - if (isfinalfeasible() || DBG_ENABLED()) - print_summary(); - - if ((diverge = get_next_backtrack()) == NULL) - return false; - - if (DBG_ENABLED()) { - printf("Next execution will diverge at:\n"); - diverge->print(); - } - - reset_to_initial_state(); - return true; -} - -ModelAction * ModelChecker::get_last_conflict(ModelAction *act) +void ModelChecker::execute_sleep_set() { - switch (act->get_type()) { - case ATOMIC_READ: - case ATOMIC_WRITE: - case 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; - } - break; - } - case ATOMIC_LOCK: - case 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 (act->is_conflicting_lock(prev)) - return prev; - } - break; - } - case 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 (!act->same_thread(prev)&&prev->is_failed_trylock()) - return prev; - } - break; - } - default: - break; - } - return NULL; -} - -/** This method find backtracking points where we should try to - * reorder the parameter ModelAction against. - * - * @param the ModelAction to find backtracking points for. - */ -void ModelChecker::set_backtracking(ModelAction *act) -{ - Thread *t = get_thread(act); - ModelAction * prev = get_last_conflict(act); - if (prev == NULL) - return; - - Node * node = prev->get_node()->get_parent(); - - int low_tid, high_tid; - if (node->is_enabled(t)) { - low_tid = id_to_int(act->get_tid()); - high_tid = low_tid+1; - } else { - low_tid = 0; - high_tid = get_num_threads(); - } - - for(int i = low_tid; i < high_tid; i++) { + for (unsigned int i = 0; i < get_num_threads(); i++) { thread_id_t tid = int_to_id(i); - if (!node->is_enabled(tid)) - continue; - - /* Check if this has been explored already */ - if (node->has_been_explored(tid)) - continue; - - /* See if fairness allows */ - if (model->params.fairwindow != 0 && !node->has_priority(tid)) { - bool unfair=false; - for(int t=0;tget_num_threads();t++) { - thread_id_t tother=int_to_id(t); - if (node->is_enabled(tother) && node->has_priority(tother)) { - unfair=true; - break; - } - } - if (unfair) - continue; - } - - /* Cache the latest backtracking point */ - if (!priv->next_backtrack || *prev > *priv->next_backtrack) - priv->next_backtrack = prev; - - /* If this is a new backtracking point, mark the tree */ - if (!node->set_backtrack(tid)) - continue; - DEBUG("Setting backtrack: conflict = %d, instead tid = %d\n", - id_to_int(prev->get_tid()), - id_to_int(t->get_id())); - if (DBG_ENABLED()) { - prev->print(); - act->print(); - } - } -} - -/** - * Returns last backtracking point. The model checker will explore a different - * path for this point in the next execution. - * @return The ModelAction at which the next execution should diverge. - */ -ModelAction * ModelChecker::get_next_backtrack() -{ - ModelAction *next = priv->next_backtrack; - priv->next_backtrack = NULL; - return next; -} - -/** - * Processes a read or rmw model action. - * @param curr is the read model action to process. - * @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, bool second_part_of_rmw) -{ - uint64_t value; - bool updated = false; - while (true) { - const ModelAction *reads_from = curr->get_node()->get_read_from(); - if (reads_from != NULL) { - mo_graph->startChanges(); - - value = reads_from->get_value(); - bool r_status = false; - - if (!second_part_of_rmw) { - check_recency(curr, reads_from); - r_status = r_modification_order(curr, reads_from); - } - - - if (!second_part_of_rmw&&!isfeasible()&&(curr->get_node()->increment_read_from()||curr->get_node()->increment_future_value())) { - mo_graph->rollbackChanges(); - too_many_reads = false; - continue; - } - - curr->read_from(reads_from); - mo_graph->commitChanges(); - updated |= r_status; - } else if (!second_part_of_rmw) { - /* Read from future value */ - value = curr->get_node()->get_future_value(); - modelclock_t expiration = curr->get_node()->get_future_value_expiration(); - curr->read_from(NULL); - Promise *valuepromise = new Promise(curr, value, expiration); - promises->push_back(valuepromise); - } - get_thread(curr)->set_return_value(value); - return updated; - } -} - -/** - * Processes a lock, trylock, or unlock model action. @param curr is - * the read model action to process. - * - * The try lock operation checks whether the lock is taken. If not, - * it falls to the normal lock operation case. If so, it returns - * fail. - * - * The lock operation has already been checked that it is enabled, so - * it just grabs the lock and synchronizes with the previous unlock. - * - * The unlock operation has to re-enable all of the threads that are - * waiting on the lock. - * - * @return True if synchronization was updated; false otherwise - */ -bool ModelChecker::process_mutex(ModelAction *curr) { - std::mutex *mutex = (std::mutex *)curr->get_location(); - struct std::mutex_state *state = mutex->get_state(); - switch (curr->get_type()) { - case ATOMIC_TRYLOCK: { - bool success = !state->islocked; - curr->set_try_lock(success); - if (!success) { - get_thread(curr)->set_return_value(0); - break; - } - get_thread(curr)->set_return_value(1); - } - //otherwise fall into the lock case - case ATOMIC_LOCK: { - if (curr->get_cv()->getClock(state->alloc_tid) <= state->alloc_clock) { - printf("Lock access before initialization\n"); - set_assert(); - } - state->islocked = true; - ModelAction *unlock = get_last_unlock(curr); - //synchronize with the previous unlock statement - if (unlock != NULL) { - curr->synchronize_with(unlock); - return true; - } - break; - } - case ATOMIC_UNLOCK: { - //unlock the lock - state->islocked = false; - //wake up the other threads - action_list_t *waiters = lock_waiters_map->get_safe_ptr(curr->get_location()); - //activate all the waiting threads - for (action_list_t::iterator rit = waiters->begin(); rit != waiters->end(); rit++) { - scheduler->wake(get_thread(*rit)); - } - waiters->clear(); - break; - } - default: - ASSERT(0); - } - return false; -} - -/** - * 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; i < futurevalues->size(); 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; + Thread *thr = get_thread(tid); + if (scheduler->is_sleep_set(thr) && thr->get_pending()) { + thr->get_pending()->set_sleep_flag(); } - futurevalues->resize(0); } - - mo_graph->commitChanges(); - get_thread(curr)->set_return_value(VALUE_NONE); - return updated_mod_order || updated_promises; } /** - * @brief Process the current action for thread-related activity + * @brief Assert a bug in the executing program. * - * Performs current-action processing for a THREAD_* ModelAction. Proccesses - * may include setting Thread status, completing THREAD_FINISH/THREAD_JOIN - * synchronization, etc. This function is a no-op for non-THREAD actions - * (e.g., ATOMIC_{READ,WRITE,RMW,LOCK}, etc.) + * Use this function to assert any sort of bug in the user program. If the + * current trace is feasible (actually, a prefix of some feasible execution), + * then this execution will be aborted, printing the appropriate message. If + * the current trace is not yet feasible, the error message will be stashed and + * printed if the execution ever becomes feasible. * - * @param curr The current action - * @return True if synchronization was updated or a thread completed + * @param msg Descriptive message for the bug (do not include newline char) + * @return True if bug is immediately-feasible */ -bool ModelChecker::process_thread_action(ModelAction *curr) +bool ModelChecker::assert_bug(const char *msg, ...) { - bool updated = false; + char str[800]; - switch (curr->get_type()) { - case THREAD_CREATE: { - Thread *th = (Thread *)curr->get_location(); - th->set_creation(curr); - break; - } - case THREAD_JOIN: { - Thread *waiting, *blocking; - waiting = get_thread(curr); - blocking = (Thread *)curr->get_location(); - if (!blocking->is_complete()) { - blocking->push_wait_list(curr); - scheduler->sleep(waiting); - } else { - do_complete_join(curr); - updated = true; /* trigger rel-seq checks */ - } - break; - } - case THREAD_FINISH: { - Thread *th = get_thread(curr); - while (!th->wait_list_empty()) { - ModelAction *act = th->pop_wait_list(); - Thread *wake = get_thread(act); - scheduler->wake(wake); - do_complete_join(act); - updated = true; /* trigger rel-seq checks */ - } - th->complete(); - updated = true; /* trigger rel-seq checks */ - break; - } - case THREAD_START: { - check_promises(NULL, curr->get_cv()); - break; - } - default: - break; - } + va_list ap; + va_start(ap, msg); + vsnprintf(str, sizeof(str), msg, ap); + va_end(ap); - return updated; + return execution->assert_bug(str); } /** - * Initialize the current action by performing one or more of the following - * actions, as appropriate: merging RMWR and RMWC/RMW actions, stepping forward - * in the NodeStack, manipulating backtracking sets, allocating and - * initializing clock vectors, and computing the promises to fulfill. - * - * @param curr The current action, as passed from the user context; may be - * freed/invalidated after the execution of this function - * @return The current action, as processed by the ModelChecker. Is only the - * same as the parameter @a curr if this is a newly-explored action. + * @brief Assert a bug in the executing program, asserted by a user thread + * @see ModelChecker::assert_bug + * @param msg Descriptive message for the bug (do not include newline char) */ -ModelAction * ModelChecker::initialize_curr_action(ModelAction *curr) +void ModelChecker::assert_user_bug(const char *msg) { - ModelAction *newcurr; - - if (curr->is_rmwc() || curr->is_rmw()) { - newcurr = process_rmw(curr); - delete curr; - - if (newcurr->is_rmw()) - compute_promises(newcurr); - return newcurr; - } - - curr->set_seq_number(get_next_seq_num()); - - newcurr = node_stack->explore_action(curr, scheduler->get_enabled()); - if (newcurr) { - /* First restore type and order in case of RMW operation */ - if (curr->is_rmwr()) - newcurr->copy_typeandorder(curr); - - ASSERT(curr->get_location() == newcurr->get_location()); - newcurr->copy_from_new(curr); - - /* Discard duplicate ModelAction; use action from NodeStack */ - delete curr; - - /* Always compute new clock vector */ - newcurr->create_cv(get_parent_action(newcurr->get_tid())); - } else { - newcurr = curr; - - /* Always compute new clock vector */ - newcurr->create_cv(get_parent_action(newcurr->get_tid())); - /* - * Perform one-time actions when pushing new ModelAction onto - * NodeStack - */ - if (newcurr->is_write()) - compute_promises(newcurr); - } - return newcurr; -} - -/** - * This method checks whether a model action is enabled at the given point. - * At this point, it checks whether a lock operation would be successful at this point. - * If not, it puts the thread in a waiter list. - * @param curr is the ModelAction to check whether it is enabled. - * @return a bool that indicates whether the action is enabled. - */ -bool ModelChecker::check_action_enabled(ModelAction *curr) { - if (curr->is_lock()) { - std::mutex * lock = (std::mutex *)curr->get_location(); - struct std::mutex_state * state = lock->get_state(); - if (state->islocked) { - //Stick the action in the appropriate waiting queue - lock_waiters_map->get_safe_ptr(curr->get_location())->push_back(curr); - return false; - } - } - - return true; + /* If feasible bug, bail out now */ + if (assert_bug(msg)) + switch_to_master(NULL); } -/** - * This is the heart of the model checker routine. It performs model-checking - * actions corresponding to a given "current action." Among other processes, it - * calculates reads-from relationships, updates synchronization clock vectors, - * forms a memory_order constraints graph, and handles replay/backtrack - * execution when running permutations of previously-observed executions. - * - * @param curr The current action to process - * @return The next Thread that must be executed. May be NULL if ModelChecker - * makes no choice (e.g., according to replay execution, combining RMW actions, - * etc.) - */ -Thread * ModelChecker::check_current_action(ModelAction *curr) +/** @brief Print bug report listing for this execution (if any bugs exist) */ +void ModelChecker::print_bugs() const { - ASSERT(curr); - - bool second_part_of_rmw = curr->is_rmwc() || curr->is_rmw(); - - if (!check_action_enabled(curr)) { - /* Make the execution look like we chose to run this action - * much later, when a lock is actually available to release */ - get_current_thread()->set_pending(curr); - scheduler->sleep(get_current_thread()); - return get_next_thread(NULL); - } - - ModelAction *newcurr = initialize_curr_action(curr); - - /* Add the action to lists before any other model-checking tasks */ - if (!second_part_of_rmw) - add_action_to_lists(newcurr); - - /* Build may_read_from set for newly-created actions */ - if (curr == newcurr && curr->is_read()) - build_reads_from_past(curr); - curr = newcurr; - - /* Initialize work_queue with the "current action" work */ - work_queue_t work_queue(1, CheckCurrWorkEntry(curr)); - - while (!work_queue.empty()) { - WorkQueueEntry work = work_queue.front(); - work_queue.pop_front(); - - switch (work.type) { - case WORK_CHECK_CURR_ACTION: { - ModelAction *act = work.action; - bool update = false; /* update this location's release seq's */ - bool update_all = false; /* update all release seq's */ - - if (process_thread_action(curr)) - update_all = true; - - if (act->is_read() && process_read(act, second_part_of_rmw)) - update = true; - - if (act->is_write() && process_write(act)) - update = true; + SnapVector *bugs = execution->get_bugs(); - if (act->is_mutex_op() && process_mutex(act)) - update_all = true; - - if (update_all) - work_queue.push_back(CheckRelSeqWorkEntry(NULL)); - else if (update) - 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 Complete verification of work_queue */ - ModelAction *act = work.action; - bool updated = false; - - if (act->is_read()) { - const ModelAction *rf = act->get_reads_from(); - if (rf != NULL && r_modification_order(act, rf)) - updated = true; - } - if (act->is_write()) { - if (w_modification_order(act)) - updated = true; - } - mo_graph->commitChanges(); - - if (updated) - work_queue.push_back(CheckRelSeqWorkEntry(act->get_location())); - break; - } - default: - ASSERT(false); - break; - } - } - - check_curr_backtracking(curr); - - set_backtracking(curr); - - return get_next_thread(curr); + model_print("Bug report: %zu bug%s detected\n", + bugs->size(), + bugs->size() > 1 ? "s" : ""); + for (unsigned int i = 0; i < bugs->size(); i++) + (*bugs)[i]->print(); } /** - * Complete a THREAD_JOIN operation, by synchronizing with the THREAD_FINISH - * operation from the Thread it is joining with. Must be called after the - * completion of the Thread in question. - * @param join The THREAD_JOIN action - */ -void ModelChecker::do_complete_join(ModelAction *join) -{ - Thread *blocking = (Thread *)join->get_location(); - ModelAction *act = get_last_action(blocking->get_id()); - join->synchronize_with(act); -} - -void ModelChecker::check_curr_backtracking(ModelAction * curr) { - Node *currnode = curr->get_node(); - Node *parnode = currnode->get_parent(); - - if ((!parnode->backtrack_empty() || - !currnode->read_from_empty() || - !currnode->future_value_empty() || - !currnode->promise_empty()) - && (!priv->next_backtrack || - *curr > *priv->next_backtrack)) { - priv->next_backtrack = curr; - } -} - -bool ModelChecker::promises_expired() { - for (unsigned int promise_index = 0; promise_index < promises->size(); promise_index++) { - Promise *promise = (*promises)[promise_index]; - if (promise->get_expiration()used_sequence_numbers) { - return true; - } - } - return false; -} - -/** @return whether the current partial trace must be a prefix of a - * feasible trace. */ -bool ModelChecker::isfeasibleprefix() { - return promises->size() == 0 && pending_acq_rel_seq->size() == 0; -} - -/** @return whether the current partial trace is feasible. */ -bool ModelChecker::isfeasible() { - if (DBG_ENABLED() && mo_graph->checkForRMWViolation()) - DEBUG("Infeasible: RMW violation\n"); - - return !mo_graph->checkForRMWViolation() && isfeasibleotherthanRMW(); -} - -/** @return whether the current partial trace is feasible other than - * multiple RMW reading from the same store. */ -bool ModelChecker::isfeasibleotherthanRMW() { - if (DBG_ENABLED()) { - if (mo_graph->checkForCycles()) - DEBUG("Infeasible: modification order cycles\n"); - if (failed_promise) - DEBUG("Infeasible: failed promise\n"); - if (too_many_reads) - DEBUG("Infeasible: too many reads\n"); - if (bad_synchronization) - DEBUG("Infeasible: bad synchronization ordering\n"); - if (promises_expired()) - DEBUG("Infeasible: promises expired\n"); - } - return !mo_graph->checkForCycles() && !failed_promise && !too_many_reads && !bad_synchronization && !promises_expired(); -} - -/** Returns whether the current completed trace is feasible. */ -bool ModelChecker::isfinalfeasible() { - if (DBG_ENABLED() && promises->size() != 0) - DEBUG("Infeasible: unrevolved promises\n"); - - return isfeasible() && promises->size() == 0; -} - -/** Close out a RMWR by converting previous RMWR into a RMW or READ. */ -ModelAction * ModelChecker::process_rmw(ModelAction *act) { - ModelAction *lastread = get_last_action(act->get_tid()); - lastread->process_rmw(act); - if (act->is_rmw() && lastread->get_reads_from()!=NULL) { - mo_graph->addRMWEdge(lastread->get_reads_from(), lastread); - mo_graph->commitChanges(); - } - return lastread; -} - -/** - * Checks whether a thread has read from the same write for too many times - * without seeing the effects of a later write. - * - * Basic idea: - * 1) there must a different write that we could read from that would satisfy the modification order, - * 2) we must have read from the same value in excess of maxreads times, and - * 3) that other write must have been in the reads_from set for maxreads times. - * - * If so, we decide that the execution is no longer feasible. - */ -void ModelChecker::check_recency(ModelAction *curr, const ModelAction *rf) { - if (params.maxreads != 0) { - - if (curr->get_node()->get_read_from_size() <= 1) - return; - //Must make sure that execution is currently feasible... We could - //accidentally clear by rolling back - if (!isfeasible()) - return; - std::vector *thrd_lists = obj_thrd_map->get_safe_ptr(curr->get_location()); - int tid = id_to_int(curr->get_tid()); - - /* Skip checks */ - if ((int)thrd_lists->size() <= tid) - return; - action_list_t *list = &(*thrd_lists)[tid]; - - action_list_t::reverse_iterator rit = list->rbegin(); - /* Skip past curr */ - for (; (*rit) != curr; rit++) - ; - /* go past curr now */ - rit++; - - action_list_t::reverse_iterator ritcopy = rit; - //See if we have enough reads from the same value - int count = 0; - for (; count < params.maxreads; rit++,count++) { - if (rit==list->rend()) - return; - ModelAction *act = *rit; - if (!act->is_read()) - return; - - if (act->get_reads_from() != rf) - return; - if (act->get_node()->get_read_from_size() <= 1) - return; - } - for (int i = 0; iget_node()->get_read_from_size(); i++) { - //Get write - const ModelAction * write = curr->get_node()->get_read_from_at(i); - - //Need a different write - if (write==rf) - continue; - - /* Test to see whether this is a feasible write to read from*/ - mo_graph->startChanges(); - r_modification_order(curr, write); - bool feasiblereadfrom = isfeasible(); - mo_graph->rollbackChanges(); - - if (!feasiblereadfrom) - continue; - rit = ritcopy; - - bool feasiblewrite = true; - //new we need to see if this write works for everyone - - for (int loop = count; loop>0; loop--,rit++) { - ModelAction *act=*rit; - bool foundvalue = false; - for (int j = 0; jget_node()->get_read_from_size(); j++) { - if (act->get_node()->get_read_from_at(i)==write) { - foundvalue = true; - break; - } - } - if (!foundvalue) { - feasiblewrite = false; - break; - } - } - if (feasiblewrite) { - too_many_reads = true; - return; - } - } - } -} - -/** - * 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 - */ -bool ModelChecker::r_modification_order(ModelAction *curr, const ModelAction *rf) -{ - std::vector *thrd_lists = obj_thrd_map->get_safe_ptr(curr->get_location()); - unsigned int i; - bool added = false; - ASSERT(curr->is_read()); - - /* Iterate over all threads */ - for (i = 0; i < thrd_lists->size(); i++) { - /* Iterate over actions in thread, starting from most recent */ - action_list_t *list = &(*thrd_lists)[i]; - action_list_t::reverse_iterator rit; - for (rit = list->rbegin(); rit != list->rend(); rit++) { - ModelAction *act = *rit; - - /* - * Include at most one act per-thread that "happens - * before" curr. Don't consider reflexively. - */ - if (act->happens_before(curr) && act != curr) { - if (act->is_write()) { - if (rf != act) { - mo_graph->addEdge(act, rf); - added = true; - } - } else { - const ModelAction *prevreadfrom = act->get_reads_from(); - //if the previous read is unresolved, keep going... - if (prevreadfrom == NULL) - continue; - - if (rf != prevreadfrom) { - mo_graph->addEdge(prevreadfrom, rf); - added = true; - } - } - break; - } - } - } - - return added; -} - -/** 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. + * @brief Record end-of-execution stats * - * @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()); - unsigned int i; - ASSERT(curr->is_read()); - - /* Iterate over all threads */ - for (i = 0; i < thrd_lists->size(); i++) { - /* Iterate over actions in thread, starting from most recent */ - action_list_t *list = &(*thrd_lists)[i]; - action_list_t::reverse_iterator rit; - ModelAction *lastact = NULL; - - /* Find last action that happens after curr that is either not curr or a rmw */ - for (rit = list->rbegin(); rit != list->rend(); rit++) { - ModelAction *act = *rit; - if (curr->happens_before(act) && (curr != act || curr->is_rmw())) { - lastact = act; - } else - break; - } - - /* Include at most one act per-thread that "happens before" curr */ - if (lastact != NULL) { - if (lastact==curr) { - //Case 1: The resolved read is a RMW, and we need to make sure - //that the write portion of the RMW mod order after rf - - mo_graph->addEdge(rf, lastact); - } else if (lastact->is_read()) { - //Case 2: The resolved read is a normal read and the next - //operation is a read, and we need to make sure the value read - //is mod ordered after rf - - const ModelAction *postreadfrom = lastact->get_reads_from(); - if (postreadfrom != NULL&&rf != postreadfrom) - mo_graph->addEdge(rf, postreadfrom); - } else { - //Case 3: The resolved read is a normal read and the next - //operation is a write, and we need to make sure that the - //write is mod ordered after rf - if (lastact!=rf) - mo_graph->addEdge(rf, lastact); - } - break; - } + * Must be run when exiting an execution. Records various stats. + * @see struct execution_stats + */ +void ModelChecker::record_stats() +{ + stats.num_total++; + if (!execution->isfeasibleprefix()) + stats.num_infeasible++; + else if (execution->have_bug_reports()) + stats.num_buggy_executions++; + else if (execution->is_complete_execution()) + stats.num_complete++; + else { + stats.num_redundant++; + + /** + * @todo We can violate this ASSERT() when fairness/sleep sets + * conflict to cause an execution to terminate, e.g. with: + * Scheduler: [0: disabled][1: disabled][2: sleep][3: current, enabled] + */ + //ASSERT(scheduler->all_threads_sleeping()); } } -/** - * 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 - */ -bool ModelChecker::w_modification_order(ModelAction *curr) +/** @brief Print execution stats */ +void ModelChecker::print_stats() const { - std::vector *thrd_lists = obj_thrd_map->get_safe_ptr(curr->get_location()); - unsigned int i; - bool added = false; - ASSERT(curr->is_write()); - - if (curr->is_seqcst()) { - /* We have to at least see the last sequentially consistent write, - so we are initialized. */ - ModelAction *last_seq_cst = get_last_seq_cst(curr); - if (last_seq_cst != NULL) { - mo_graph->addEdge(last_seq_cst, curr); - added = true; - } - } - - /* Iterate over all threads */ - for (i = 0; i < thrd_lists->size(); i++) { - /* Iterate over actions in thread, starting from most recent */ - action_list_t *list = &(*thrd_lists)[i]; - action_list_t::reverse_iterator rit; - for (rit = list->rbegin(); rit != list->rend(); rit++) { - ModelAction *act = *rit; - if (act == curr) { - /* - * 1) If RMW and it actually read from something, then we - * already have all relevant edges, so just skip to next - * thread. - * - * 2) If RMW and it didn't read from anything, we should - * whatever edge we can get to speed up convergence. - * - * 3) If normal write, we need to look at earlier actions, so - * continue processing list. - */ - if (curr->is_rmw()) { - if (curr->get_reads_from()!=NULL) - break; - else - continue; - } else - continue; - } - - /* - * Include at most one act per-thread that "happens - * before" curr - */ - if (act->happens_before(curr)) { - /* - * Note: if act is RMW, just add edge: - * act --mo--> curr - * The following edge should be handled elsewhere: - * readfrom(act) --mo--> act - */ - if (act->is_write()) - mo_graph->addEdge(act, curr); - else if (act->is_read()) { - //if previous read accessed a null, just keep going - if (act->get_reads_from() == NULL) - continue; - mo_graph->addEdge(act->get_reads_from(), curr); - } - added = true; - break; - } else if (act->is_read() && !act->is_synchronizing(curr) && - !act->same_thread(curr)) { - /* We have an action that: - (1) did not happen before us - (2) is a read and we are a write - (3) cannot synchronize with us - (4) is in a different thread - => - that read could potentially read from our write. - */ - if (thin_air_constraint_may_allow(curr, act)) { - if (isfeasible() || - (curr->is_rmw() && act->is_rmw() && curr->get_reads_from() == act->get_reads_from() && isfeasibleotherthanRMW())) { - struct PendingFutureValue pfv = {curr->get_value(),curr->get_seq_number()+params.maxfuturedelay,act}; - futurevalues->push_back(pfv); - } - } - } - } - } - - return added; -} - -/** Arbitrary reads from the future are not allowed. Section 29.3 - * part 9 places some constraints. This method checks one result of constraint - * constraint. Others require compiler support. */ -bool ModelChecker::thin_air_constraint_may_allow(const ModelAction * writer, const ModelAction *reader) { - if (!writer->is_rmw()) - return true; - - if (!reader->is_rmw()) - return true; - - for (const ModelAction *search = writer->get_reads_from(); search != NULL; search = search->get_reads_from()) { - if (search == reader) - return false; - if (search->get_tid() == reader->get_tid() && - search->happens_before(reader)) - break; - } - - return true; + model_print("Number of complete, bug-free executions: %d\n", stats.num_complete); + model_print("Number of redundant executions: %d\n", stats.num_redundant); + model_print("Number of buggy executions: %d\n", stats.num_buggy_executions); + model_print("Number of infeasible executions: %d\n", stats.num_infeasible); + model_print("Total executions: %d\n", stats.num_total); + model_print("Total nodes created: %d\n", node_stack->get_total_nodes()); } /** - * Finds the head(s) of the release sequence(s) containing a given ModelAction. - * The ModelAction under consideration is expected to be taking part in - * release/acquire synchronization as an object of the "reads from" relation. - * Note that this can only provide release sequence support for RMW chains - * which do not read from the future, as those actions cannot be traced until - * their "promise" is fulfilled. Similarly, we may not even establish the - * presence of a release sequence with certainty, as some modification order - * constraints may be decided further in the future. Thus, this function - * "returns" two pieces of data: a pass-by-reference vector of @a release_heads - * and a boolean representing certainty. - * - * @todo Finish lazy updating, when promises are fulfilled in the future - * @param rf The action that might be part of a release sequence. Must be a - * write. - * @param release_heads A pass-by-reference style return parameter. After - * execution of this function, release_heads will contain the heads of all the - * relevant release sequences, if any exists - * @return true, if the ModelChecker is certain that release_heads is complete; - * false otherwise + * @brief End-of-exeuction print + * @param printbugs Should any existing bugs be printed? */ -bool ModelChecker::release_seq_head(const ModelAction *rf, rel_heads_list_t *release_heads) const +void ModelChecker::print_execution(bool printbugs) const { - /* Only check for release sequences if there are no cycles */ - if (mo_graph->checkForCycles()) - return false; - - while (rf) { - ASSERT(rf->is_write()); - - if (rf->is_release()) - release_heads->push_back(rf); - if (!rf->is_rmw()) - break; /* End of RMW chain */ + model_print("Program output from execution %d:\n", + get_execution_number()); + print_program_output(); - /** @todo Need to be smarter here... In the linux lock - * example, this will run to the beginning of the program for - * every acquire. */ - /** @todo The way to be smarter here is to keep going until 1 - * thread has a release preceded by an acquire and you've seen - * both. */ - - /* acq_rel RMW is a sufficient stopping condition */ - if (rf->is_acquire() && rf->is_release()) - return true; /* complete */ - - rf = rf->get_reads_from(); - }; - if (!rf) { - /* read from future: need to settle this later */ - return false; /* incomplete */ - } - - if (rf->is_release()) - return true; /* complete */ - - /* else relaxed write; check modification order for contiguous subsequence - * -> rf must be same thread as release */ - int tid = id_to_int(rf->get_tid()); - std::vector *thrd_lists = obj_thrd_map->get_safe_ptr(rf->get_location()); - action_list_t *list = &(*thrd_lists)[tid]; - action_list_t::const_reverse_iterator rit; - - /* Find rf in the thread list */ - rit = std::find(list->rbegin(), list->rend(), rf); - ASSERT(rit != list->rend()); + if (params.verbose >= 2) { + model_print("\nEarliest divergence point since last feasible execution:\n"); + if (earliest_diverge) + earliest_diverge->print(); + else + model_print("(Not set)\n"); - /* Find the last write/release */ - for (; rit != list->rend(); rit++) - if ((*rit)->is_release()) - break; - if (rit == list->rend()) { - /* No write-release in this thread */ - return true; /* complete */ + model_print("\n"); + print_stats(); } - ModelAction *release = *rit; - - ASSERT(rf->same_thread(release)); - - bool certain = true; - for (unsigned int i = 0; i < thrd_lists->size(); i++) { - if (id_to_int(rf->get_tid()) == (int)i) - continue; - list = &(*thrd_lists)[i]; - - /* Can we ensure no future writes from this thread may break - * the release seq? */ - bool future_ordered = false; - ModelAction *last = get_last_action(int_to_id(i)); - if (last && (rf->happens_before(last) || - get_thread(int_to_id(i))->is_complete())) - future_ordered = true; - - for (rit = list->rbegin(); rit != list->rend(); rit++) { - const ModelAction *act = *rit; - /* Reach synchronization -> this thread is complete */ - if (act->happens_before(release)) - break; - if (rf->happens_before(act)) { - future_ordered = true; - continue; - } - - /* Only writes can break release sequences */ - if (!act->is_write()) - continue; - - /* Check modification order */ - if (mo_graph->checkReachable(rf, act)) { - /* rf --mo--> act */ - future_ordered = true; - continue; - } - if (mo_graph->checkReachable(act, release)) - /* act --mo--> release */ - break; - if (mo_graph->checkReachable(release, act) && - mo_graph->checkReachable(act, rf)) { - /* release --mo-> act --mo--> rf */ - return true; /* complete */ - } - certain = false; - } - if (!future_ordered) - return false; /* This thread is uncertain */ + /* Don't print invalid bugs */ + if (printbugs && execution->have_bug_reports()) { + model_print("\n"); + print_bugs(); } - if (certain) - release_heads->push_back(release); - return certain; -} - -/** - * A public interface for getting the release sequence head(s) with which a - * given ModelAction must synchronize. This function only returns a non-empty - * result when it can locate a release sequence head with certainty. Otherwise, - * it may mark the internal state of the ModelChecker so that it will handle - * the release sequence at a later time, causing @a act to update its - * synchronization at some later point in execution. - * @param act The 'acquire' action that may read from a release sequence - * @param release_heads A pass-by-reference return parameter. Will be filled - * with the head(s) of the release sequence(s), if they exists with certainty. - * @see ModelChecker::release_seq_head - */ -void ModelChecker::get_release_seq_heads(ModelAction *act, rel_heads_list_t *release_heads) -{ - const ModelAction *rf = act->get_reads_from(); - bool complete; - complete = release_seq_head(rf, release_heads); - if (!complete) { - /* add act to 'lazy checking' list */ - pending_acq_rel_seq->push_back(act); - } + model_print("\n"); + execution->print_summary(); } /** - * Attempt to resolve all stashed operations that might synchronize with a - * release sequence for a given location. This implements the "lazy" portion of - * determining whether or not a release sequence was contiguous, since not all - * modification order information is present at the time an action occurs. + * Queries the model-checker for more executions to explore and, if one + * exists, resets the model-checker state to execute a new execution. * - * @param location The location/object that should be checked for release - * sequence resolutions. A NULL value means to check all locations. - * @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) + * @return If there are more executions to explore, return true. Otherwise, + * return false. */ -bool ModelChecker::resolve_release_sequences(void *location, work_queue_t *work_queue) +bool ModelChecker::next_execution() { - bool updated = false; - std::vector::iterator it = pending_acq_rel_seq->begin(); - while (it != pending_acq_rel_seq->end()) { - ModelAction *act = *it; - - /* Only resolve sequences on the given location, if provided */ - if (location && act->get_location() != location) { - it++; - continue; - } - - const ModelAction *rf = act->get_reads_from(); - rel_heads_list_t release_heads; - bool complete; - complete = release_seq_head(rf, &release_heads); - for (unsigned int i = 0; i < release_heads.size(); i++) { - if (!act->has_synchronized_with(release_heads[i])) { - if (act->synchronize_with(release_heads[i])) - updated = true; - else - set_bad_synchronization(); - } - } + DBG(); + /* Is this execution a feasible execution that's worth bug-checking? */ + bool complete = execution->isfeasibleprefix() && + (execution->is_complete_execution() || + execution->have_bug_reports()); - if (updated) { - /* Re-check all pending release sequences */ - work_queue->push_back(CheckRelSeqWorkEntry(NULL)); - /* Re-check act for mo_graph edges */ - work_queue->push_back(MOEdgeWorkEntry(act)); + /* End-of-execution bug checks */ + if (complete) { + if (execution->is_deadlocked()) + assert_bug("Deadlock detected"); - /* propagate synchronization to later actions */ - action_list_t::reverse_iterator rit = action_trace->rbegin(); - for (; (*rit) != act; rit++) { - ModelAction *propagate = *rit; - if (act->happens_before(propagate)) { - propagate->synchronize_with(act); - /* Re-check 'propagate' for mo_graph edges */ - work_queue->push_back(MOEdgeWorkEntry(propagate)); - } - } - } - if (complete) - it = pending_acq_rel_seq->erase(it); - else - it++; + checkDataRaces(); + run_trace_analyses(); } - // If we resolved promises or data races, see if we have realized a data race. - if (checkDataRaces()) { - set_assert(); - } - - return updated; -} - -/** - * Performs various bookkeeping operations for the current ModelAction. For - * instance, adds action to the per-object, per-thread action vector and to the - * action trace list of all thread actions. - * - * @param act is the ModelAction to add. - */ -void ModelChecker::add_action_to_lists(ModelAction *act) -{ - int tid = id_to_int(act->get_tid()); - action_trace->push_back(act); - - obj_map->get_safe_ptr(act->get_location())->push_back(act); - - std::vector *vec = obj_thrd_map->get_safe_ptr(act->get_location()); - if (tid >= (int)vec->size()) - vec->resize(priv->next_thread_id); - (*vec)[tid].push_back(act); - - if ((int)thrd_last_action->size() <= tid) - thrd_last_action->resize(get_num_threads()); - (*thrd_last_action)[tid] = act; -} + record_stats(); -/** - * @brief Get the last action performed by a particular Thread - * @param tid The thread ID of the Thread in question - * @return The last action in the thread - */ -ModelAction * ModelChecker::get_last_action(thread_id_t tid) const -{ - int threadid = id_to_int(tid); - if (threadid < (int)thrd_last_action->size()) - return (*thrd_last_action)[id_to_int(tid)]; + /* Output */ + if (params.verbose || (complete && execution->have_bug_reports())) + print_execution(complete); else - return NULL; -} - -/** - * Gets the last memory_order_seq_cst write (in the total global sequence) - * performed on a particular object (i.e., memory location), not including the - * current action. - * @param curr The current ModelAction; also denotes the object location to - * check - * @return The last seq_cst write - */ -ModelAction * ModelChecker::get_last_seq_cst(ModelAction *curr) const -{ - void *location = curr->get_location(); - action_list_t *list = obj_map->get_safe_ptr(location); - /* Find: max({i in dom(S) | seq_cst(t_i) && isWrite(t_i) && samevar(t_i, t)}) */ - action_list_t::reverse_iterator rit; - for (rit = list->rbegin(); rit != list->rend(); rit++) - if ((*rit)->is_write() && (*rit)->is_seqcst() && (*rit) != curr) - return *rit; - return NULL; -} - -/** - * Gets the last unlock operation performed on a particular mutex (i.e., memory - * location). This function identifies the mutex according to the current - * action, which is presumed to perform on the same mutex. - * @param curr The current ModelAction; also denotes the object location to - * check - * @return The last unlock operation - */ -ModelAction * ModelChecker::get_last_unlock(ModelAction *curr) const -{ - void *location = curr->get_location(); - action_list_t *list = obj_map->get_safe_ptr(location); - /* Find: max({i in dom(S) | isUnlock(t_i) && samevar(t_i, t)}) */ - action_list_t::reverse_iterator rit; - for (rit = list->rbegin(); rit != list->rend(); rit++) - if ((*rit)->is_unlock()) - return *rit; - return NULL; -} - -ModelAction * ModelChecker::get_parent_action(thread_id_t tid) -{ - ModelAction *parent = get_last_action(tid); - if (!parent) - parent = get_thread(tid)->get_creation(); - return parent; -} - -/** - * Returns the clock vector for a given thread. - * @param tid The thread whose clock vector we want - * @return Desired clock vector - */ -ClockVector * ModelChecker::get_cv(thread_id_t tid) -{ - return get_parent_action(tid)->get_cv(); -} - -/** - * Resolve a set of Promises with a current write. The set is provided in the - * Node corresponding to @a write. - * @param write The ModelAction that is fulfilling Promises - * @return True if promises were resolved; false otherwise - */ -bool ModelChecker::resolve_promises(ModelAction *write) -{ - bool resolved = false; + clear_program_output(); - for (unsigned int i = 0, promise_index = 0; promise_index < promises->size(); i++) { - Promise *promise = (*promises)[promise_index]; - if (write->get_node()->get_promise(i)) { - ModelAction *read = promise->get_action(); - if (read->is_rmw()) { - mo_graph->addRMWEdge(write, read); - } - read->read_from(write); - //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); - //Make sure the promise's value matches the write's value - ASSERT(promise->get_value() == write->get_value()); - - delete(promise); - promises->erase(promises->begin() + promise_index); - resolved = true; - } else - promise_index++; - } - return resolved; -} - -/** - * Compute the set of promises that could potentially be satisfied by this - * action. Note that the set computation actually appears in the Node, not in - * ModelChecker. - * @param curr The ModelAction that may satisfy promises - */ -void ModelChecker::compute_promises(ModelAction *curr) -{ - for (unsigned int i = 0; i < promises->size(); i++) { - Promise *promise = (*promises)[i]; - const ModelAction *act = promise->get_action(); - if (!act->happens_before(curr) && - act->is_read() && - !act->is_synchronizing(curr) && - !act->same_thread(curr) && - promise->get_value() == curr->get_value()) { - curr->get_node()->set_promise(i); - } - } -} - -/** Checks promises in response to change in ClockVector Threads. */ -void ModelChecker::check_promises(ClockVector *old_cv, ClockVector *merge_cv) -{ - for (unsigned int i = 0; i < promises->size(); i++) { - Promise *promise = (*promises)[i]; - const ModelAction *act = promise->get_action(); - if ((old_cv == NULL || !old_cv->synchronized_since(act)) && - merge_cv->synchronized_since(act)) { - //This thread is no longer able to send values back to satisfy the promise - int num_synchronized_threads = promise->increment_threads(); - if (num_synchronized_threads == get_num_threads()) { - //Promise has failed - failed_promise = true; - return; - } - } - } -} - -/** - * Build up an initial set of all past writes that this 'read' action may read - * from. This set is determined by the clock vector's "happens before" - * relationship. - * @param curr is the current ModelAction that we are exploring; it must be a - * 'read' operation. - */ -void ModelChecker::build_reads_from_past(ModelAction *curr) -{ - std::vector *thrd_lists = obj_thrd_map->get_safe_ptr(curr->get_location()); - unsigned int i; - ASSERT(curr->is_read()); - - ModelAction *last_seq_cst = NULL; - - /* Track whether this object has been initialized */ - bool initialized = false; - - if (curr->is_seqcst()) { - last_seq_cst = get_last_seq_cst(curr); - /* We have to at least see the last sequentially consistent write, - so we are initialized. */ - if (last_seq_cst != NULL) - initialized = true; - } - - /* Iterate over all threads */ - for (i = 0; i < thrd_lists->size(); i++) { - /* Iterate over actions in thread, starting from most recent */ - action_list_t *list = &(*thrd_lists)[i]; - action_list_t::reverse_iterator rit; - for (rit = list->rbegin(); rit != list->rend(); rit++) { - ModelAction *act = *rit; - - /* Only consider 'write' actions */ - if (!act->is_write() || act == curr) - continue; - - /* Don't consider more than one seq_cst write if we are a seq_cst read. */ - if (!curr->is_seqcst() || (!act->is_seqcst() && (last_seq_cst == NULL || !act->happens_before(last_seq_cst))) || act == last_seq_cst) { - DEBUG("Adding action to may_read_from:\n"); - if (DBG_ENABLED()) { - act->print(); - curr->print(); - } - curr->get_node()->add_read_from(act); - } - - /* Include at most one act per-thread that "happens before" curr */ - if (act->happens_before(curr)) { - initialized = true; - break; - } - } - } - - if (!initialized) { - /** @todo Need a more informative way of reporting errors. */ - printf("ERROR: may read from uninitialized atomic\n"); - } - - if (DBG_ENABLED() || !initialized) { - printf("Reached read action:\n"); - curr->print(); - printf("Printing may_read_from\n"); - curr->get_node()->print_may_read_from(); - printf("End printing may_read_from\n"); - } - - ASSERT(initialized); -} - -static void print_list(action_list_t *list) -{ - action_list_t::iterator it; - - printf("---------------------------------------------------------------------\n"); - printf("Trace:\n"); + if (complete) + earliest_diverge = NULL; - for (it = list->begin(); it != list->end(); it++) { - (*it)->print(); - } - printf("---------------------------------------------------------------------\n"); -} + if ((diverge = execution->get_next_backtrack()) == NULL) + return false; -#if SUPPORT_MOD_ORDER_DUMP -void ModelChecker::dumpGraph(char *filename) { - char buffer[200]; - sprintf(buffer, "%s.dot",filename); - FILE *file=fopen(buffer, "w"); - fprintf(file, "digraph %s {\n",filename); - mo_graph->dumpNodes(file); - ModelAction ** thread_array=(ModelAction **)model_calloc(1, sizeof(ModelAction *)*get_num_threads()); - - for (action_list_t::iterator it = action_trace->begin(); it != action_trace->end(); it++) { - ModelAction *action=*it; - if (action->is_read()) { - fprintf(file, "N%u [label=\"%u, T%u\"];\n", action->get_seq_number(),action->get_seq_number(), action->get_tid()); - if (action->get_reads_from()!=NULL) - fprintf(file, "N%u -> N%u[label=\"rf\", color=red];\n", action->get_seq_number(), action->get_reads_from()->get_seq_number()); - } - if (thread_array[action->get_tid()] != NULL) { - fprintf(file, "N%u -> N%u[label=\"sb\", color=blue];\n", thread_array[action->get_tid()]->get_seq_number(), action->get_seq_number()); - } - - thread_array[action->get_tid()]=action; + if (DBG_ENABLED()) { + model_print("Next execution will diverge at:\n"); + diverge->print(); } - fprintf(file,"}\n"); - model_free(thread_array); - fclose(file); -} -#endif -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 - scheduler->print(); - char buffername[100]; - sprintf(buffername, "exec%04u", num_executions); - mo_graph->dumpGraphToFile(buffername); - sprintf(buffername, "graph%04u", num_executions); - dumpGraph(buffername); -#endif - - if (!isfinalfeasible()) - printf("INFEASIBLE EXECUTION!\n"); - print_list(action_trace); - printf("\n"); -} + execution_number++; -/** - * Add a Thread to the system for the first time. Should only be called once - * per thread. - * @param t The Thread to add - */ -void ModelChecker::add_thread(Thread *t) -{ - thread_map->put(id_to_int(t->get_id()), t); - scheduler->add_thread(t); + reset_to_initial_state(); + return true; } -/** - * Removes a thread from the scheduler. - * @param the thread to remove. - */ -void ModelChecker::remove_thread(Thread *t) -{ - scheduler->remove_thread(t); +/** @brief Run trace analyses on complete trace */ +void ModelChecker::run_trace_analyses() { + for (unsigned int i = 0; i < trace_analyses.size(); i++) + trace_analyses[i]->analyze(execution->get_action_trace()); } /** @@ -1715,7 +337,7 @@ void ModelChecker::remove_thread(Thread *t) */ Thread * ModelChecker::get_thread(thread_id_t tid) const { - return thread_map->get(id_to_int(tid)); + return execution->get_thread(tid); } /** @@ -1723,9 +345,22 @@ Thread * ModelChecker::get_thread(thread_id_t tid) const * @param act The ModelAction * @return A Thread reference */ -Thread * ModelChecker::get_thread(ModelAction *act) const +Thread * ModelChecker::get_thread(const ModelAction *act) const { - return get_thread(act->get_tid()); + return execution->get_thread(act); +} + +/** + * Switch from a model-checker context to a user-thread context. This is the + * complement of ModelChecker::switch_to_master and must be called from the + * model-checker context + * + * @param thread The user-thread to switch to + */ +void ModelChecker::switch_from_master(Thread *thread) +{ + scheduler->set_current_thread(thread); + Thread::swap(&system_context, thread); } /** @@ -1735,71 +370,103 @@ Thread * ModelChecker::get_thread(ModelAction *act) const * from a user-thread context. * * @param act The current action that will be explored. May be NULL only if - * trace is exiting via an assertion (see ModelChecker::set_assert and - * ModelChecker::has_asserted). - * @return Return status from the 'swap' call (i.e., success/fail, 0/-1) + * trace is exiting via an assertion (see ModelExecution::set_assert and + * ModelExecution::has_asserted). + * @return Return the value returned by the current action */ -int ModelChecker::switch_to_master(ModelAction *act) +uint64_t ModelChecker::switch_to_master(ModelAction *act) { DBG(); Thread *old = thread_current(); - set_current_action(act); - old->set_state(THREAD_READY); - return Thread::swap(old, &system_context); + scheduler->set_current_thread(NULL); + ASSERT(!old->get_pending()); + old->set_pending(act); + if (Thread::swap(old, &system_context) < 0) { + perror("swap threads"); + exit(EXIT_FAILURE); + } + return old->get_return_value(); } -/** - * Takes the next step in the execution, if possible. - * @return Returns true (success) if a step was taken and false otherwise. - */ -bool ModelChecker::take_step() { - if (has_asserted()) - return false; +/** Wrapper to run the user's main function, with appropriate arguments */ +void user_main_wrapper(void *) +{ + user_main(model->params.argc, model->params.argv); +} - Thread *curr = thread_current(); - if (curr) { - if (curr->get_state() == THREAD_READY) { - ASSERT(priv->current_action); +bool ModelChecker::should_terminate_execution() +{ + /* Infeasible -> don't take any more steps */ + if (execution->is_infeasible()) + return true; + else if (execution->isfeasibleprefix() && execution->have_bug_reports()) { + execution->set_assert(); + return true; + } - priv->nextThread = check_current_action(priv->current_action); - priv->current_action = NULL; + if (execution->too_many_steps()) + return true; + return false; +} - if (curr->is_blocked() || curr->is_complete()) - scheduler->remove_thread(curr); - } else { - ASSERT(false); - } - } - Thread *next = scheduler->next_thread(priv->nextThread); +/** @brief Run ModelChecker for the user program */ +void ModelChecker::run() +{ + do { + thrd_t user_thread; + Thread *t = new Thread(execution->get_next_id(), &user_thread, &user_main_wrapper, NULL, NULL); + execution->add_thread(t); - /* Infeasible -> don't take any more steps */ - if (!isfeasible()) - return false; + do { + /* + * Stash next pending action(s) for thread(s). There + * should only need to stash one thread's action--the + * thread which just took a step--plus the first step + * for any newly-created thread + */ + for (unsigned int i = 0; i < get_num_threads(); i++) { + thread_id_t tid = int_to_id(i); + Thread *thr = get_thread(tid); + if (!thr->is_model_thread() && !thr->is_complete() && !thr->get_pending()) { + switch_from_master(thr); + if (thr->is_waiting_on(thr)) + assert_bug("Deadlock detected (thread %u)", i); + } + } - DEBUG("(%d, %d)\n", curr ? id_to_int(curr->get_id()) : -1, - next ? id_to_int(next->get_id()) : -1); + /* Don't schedule threads which should be disabled */ + for (unsigned int i = 0; i < get_num_threads(); i++) { + Thread *th = get_thread(int_to_id(i)); + ModelAction *act = th->get_pending(); + if (act && execution->is_enabled(th) && !execution->check_action_enabled(act)) { + scheduler->sleep(th); + } + } - /* next == NULL -> don't take any more steps */ - if (!next) - return false; + /* Catch assertions from prior take_step or from + * between-ModelAction bugs (e.g., data races) */ + if (execution->has_asserted()) + break; - next->set_state(THREAD_RUNNING); + if (!t) + t = get_next_thread(); + if (!t || t->is_model_thread()) + break; - if (next->get_pending() != NULL) { - /* restart a pending action */ - set_current_action(next->get_pending()); - next->set_pending(NULL); - next->set_state(THREAD_READY); - return true; - } + /* Consume the next action for a Thread */ + ModelAction *curr = t->get_pending(); + t->set_pending(NULL); + t = execution->take_step(curr); + } while (!should_terminate_execution()); - /* Return false only if swap fails with an error */ - return (Thread::swap(&system_context, next) == 0); -} + } while (next_execution()); -/** Runs the current execution until threre are no more steps to take. */ -void ModelChecker::finish_execution() { - DBG(); + execution->fixup_release_sequences(); + + model_print("******* Model-checking complete: *******\n"); + print_stats(); - while (take_step()); + /* Have the trace analyses dump their output. */ + for (unsigned int i = 0; i < trace_analyses.size(); i++) + trace_analyses[i]->finish(); }