X-Git-Url: http://plrg.eecs.uci.edu/git/?p=c11tester.git;a=blobdiff_plain;f=model.cc;h=3262f5e55caf992397d9134f24f2bba325cc4e87;hp=a32fbe61b3bc54405f3ee9f10881520b98e8be7f;hb=805a3e1b51dacac117b394f1c1b0220e3ae9f5e4;hpb=a660db92e26c99c47bc5c3518cd301b0e729a92d diff --git a/model.cc b/model.cc index a32fbe61..3262f5e5 100644 --- a/model.cc +++ b/model.cc @@ -2,42 +2,18 @@ #include "model.h" #include "action.h" -#include "tree.h" +#include "nodestack.h" #include "schedule.h" +#include "snapshot-interface.h" #include "common.h" +#include "clockvector.h" +#include "cyclegraph.h" #define INITIAL_THREAD_ID 0 -class Backtrack { -public: - Backtrack(ModelAction *d, action_list_t *t) { - diverge = d; - actionTrace = t; - iter = actionTrace->begin(); - } - ModelAction * get_diverge() { return diverge; } - action_list_t * get_trace() { return actionTrace; } - void advance_state() { iter++; } - ModelAction * get_state() { - return iter == actionTrace->end() ? NULL : *iter; - } -private: - ModelAction *diverge; - action_list_t *actionTrace; - /* points to position in actionTrace as we replay */ - action_list_t::iterator iter; -}; - ModelChecker *model; -void free_action_list(action_list_t *list) -{ - action_list_t::iterator it; - for (it = list->begin(); it != list->end(); it++) - delete (*it); - delete list; -} - +/** @brief Constructor */ ModelChecker::ModelChecker() : /* Initialize default scheduler */ @@ -48,86 +24,125 @@ ModelChecker::ModelChecker() num_executions(0), current_action(NULL), - exploring(NULL), + diverge(NULL), nextThread(THREAD_ID_T_NONE), action_trace(new action_list_t()), - rootNode(new TreeNode()), - currentNode(rootNode) + thread_map(new std::map), + obj_map(new std::map()), + obj_thrd_map(new std::map >()), + thrd_last_action(new std::vector(1)), + node_stack(new NodeStack()), + next_backtrack(NULL), + cyclegraph(new CycleGraph()) { } +/** @brief Destructor */ ModelChecker::~ModelChecker() { - std::map::iterator it; - for (it = thread_map.begin(); it != thread_map.end(); it++) + std::map::iterator it; + for (it = thread_map->begin(); it != thread_map->end(); it++) delete (*it).second; - thread_map.clear(); - - free_action_list(action_trace); + delete thread_map; + delete obj_thrd_map; + delete obj_map; + delete action_trace; + delete thrd_last_action; + delete node_stack; delete scheduler; - delete rootNode; + delete cyclegraph; } +/** + * Restores user program to initial state and resets all model-checker data + * structures. + */ void ModelChecker::reset_to_initial_state() { DEBUG("+++ Resetting to initial state +++\n"); - std::map::iterator it; - for (it = thread_map.begin(); it != thread_map.end(); it++) - delete (*it).second; - thread_map.clear(); - action_trace = new action_list_t(); - currentNode = rootNode; + node_stack->reset_execution(); current_action = NULL; next_thread_id = INITIAL_THREAD_ID; used_sequence_numbers = 0; - /* scheduler reset ? */ + nextThread = 0; + next_backtrack = NULL; + snapshotObject->backTrackBeforeStep(0); } +/** @returns a thread ID for a new Thread */ thread_id_t ModelChecker::get_next_id() { return next_thread_id++; } -int ModelChecker::get_next_seq_num() +/** @returns the number of user threads created during this execution */ +int ModelChecker::get_num_threads() +{ + return next_thread_id; +} + +/** @returns a sequence number for a new ModelAction */ +modelclock_t ModelChecker::get_next_seq_num() { return ++used_sequence_numbers; } +/** + * Performs the "scheduling" for the model-checker. That is, it checks if the + * model-checker has selected a "next thread to run" and returns it, if + * available. This function should be called from the Scheduler routine, where + * the Scheduler falls back to a default scheduling routine if needed. + * + * @return The next thread chosen by the model-checker. If the model-checker + * makes no selection, retuns NULL. + */ Thread * ModelChecker::schedule_next_thread() { Thread *t; if (nextThread == THREAD_ID_T_NONE) return NULL; - t = thread_map[id_to_int(nextThread)]; + t = (*thread_map)[id_to_int(nextThread)]; ASSERT(t != NULL); return t; } -/* - * get_next_replay_thread() - Choose the next thread in the replay sequence +/** + * Choose the next thread in the replay sequence. * - * If we've reached the 'diverge' point, then we pick a thread from the - * backtracking set. - * Otherwise, we simply return the next thread in the sequence. + * If the replay sequence has reached the 'diverge' point, returns a thread + * from the backtracking set. Otherwise, simply returns the next thread in the + * sequence that is being replayed. */ thread_id_t ModelChecker::get_next_replay_thread() { ModelAction *next; thread_id_t tid; - next = exploring->get_state(); - - if (next == exploring->get_diverge()) { - TreeNode *node = next->get_treenode(); + /* Have we completed exploring the preselected path? */ + if (diverge == NULL) + return THREAD_ID_T_NONE; - /* Reached divergence point; discard our current 'exploring' */ - DEBUG("*** Discard 'Backtrack' object ***\n"); - tid = node->getNextBacktrack(); - delete exploring; - exploring = NULL; + /* Else, we are trying to replay an execution */ + next = node_stack->get_next()->get_action(); + + if (next == diverge) { + Node *nextnode = next->get_node(); + /* Reached divergence point */ + if (nextnode->increment_read_from()) { + /* The next node will read from a different value */ + tid = next->get_tid(); + node_stack->pop_restofstack(2); + } else { + /* Make a different thread execute for next step */ + Node *node = nextnode->get_parent(); + tid = node->get_next_backtrack(); + node_stack->pop_restofstack(1); + } + DEBUG("*** Divergence point ***\n"); + diverge = NULL; } else { tid = next->get_tid(); } @@ -135,37 +150,31 @@ thread_id_t ModelChecker::get_next_replay_thread() return tid; } -thread_id_t ModelChecker::advance_backtracking_state() -{ - /* Have we completed exploring the preselected path? */ - if (exploring == NULL) - return THREAD_ID_T_NONE; - - /* Else, we are trying to replay an execution */ - exploring->advance_state(); - - ASSERT(exploring->get_state() != NULL); - - return get_next_replay_thread(); -} - +/** + * 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. + */ bool ModelChecker::next_execution() { DBG(); num_executions++; - print_summary(); - if ((exploring = model->get_next_backtrack()) == NULL) + + if (isfeasible() || DBG_ENABLED()) + print_summary(); + + if ((diverge = model->get_next_backtrack()) == NULL) return false; if (DBG_ENABLED()) { printf("Next execution will diverge at:\n"); - exploring->get_diverge()->print(); - print_list(exploring->get_trace()); + diverge->print(); } model->reset_to_initial_state(); - nextThread = get_next_replay_thread(); return true; } @@ -174,20 +183,19 @@ ModelAction * ModelChecker::get_last_conflict(ModelAction *act) action_type type = act->get_type(); switch (type) { - case THREAD_CREATE: - case THREAD_YIELD: - case THREAD_JOIN: - return NULL; case ATOMIC_READ: case ATOMIC_WRITE: - default: + case ATOMIC_RMW: break; + default: + return NULL; } /* linear search: from most recent to oldest */ + action_list_t *list = &(*obj_map)[act->get_location()]; action_list_t::reverse_iterator rit; - for (rit = action_trace->rbegin(); rit != action_trace->rend(); rit++) { + for (rit = list->rbegin(); rit != list->rend(); rit++) { ModelAction *prev = *rit; - if (act->is_dependent(prev)) + if (act->is_synchronizing(prev)) return prev; } return NULL; @@ -196,76 +204,349 @@ ModelAction * ModelChecker::get_last_conflict(ModelAction *act) void ModelChecker::set_backtracking(ModelAction *act) { ModelAction *prev; - TreeNode *node; + Node *node; Thread *t = get_thread(act->get_tid()); prev = get_last_conflict(act); if (prev == NULL) return; - node = prev->get_treenode(); + node = prev->get_node()->get_parent(); - while (t && !node->is_enabled(t)) + while (!node->is_enabled(t)) t = t->get_parent(); /* Check if this has been explored already */ - if (node->hasBeenExplored(t->get_id())) + if (node->has_been_explored(t->get_id())) return; + + /* Cache the latest backtracking point */ + if (!next_backtrack || *prev > *next_backtrack) + next_backtrack = prev; + /* If this is a new backtracking point, mark the tree */ - if (node->setBacktrack(t->get_id()) != 0) + if (!node->set_backtrack(t->get_id())) return; - DEBUG("Setting backtrack: conflict = %d, instead tid = %d\n", prev->get_tid(), t->get_id()); if (DBG_ENABLED()) { prev->print(); act->print(); } - - Backtrack *back = new Backtrack(prev, action_trace); - backtrack_list.push_back(back); } -Backtrack * ModelChecker::get_next_backtrack() +/** + * 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() { - Backtrack *next; - if (backtrack_list.empty()) - return NULL; - next = backtrack_list.back(); - backtrack_list.pop_back(); + ModelAction *next = next_backtrack; + next_backtrack = NULL; return next; } void ModelChecker::check_current_action(void) { ModelAction *curr = this->current_action; + ModelAction *tmp; current_action = NULL; if (!curr) { DEBUG("trying to push NULL action...\n"); return; } - nextThread = advance_backtracking_state(); - curr->set_node(currentNode); + if (curr->is_rmw()) { + //We have a RMW action + process_rmw(curr); + //Force the current thread to continue since the RMW should be atomic + nextThread = thread_current()->get_id(); + delete curr; + return; + } + + tmp = node_stack->explore_action(curr); + if (tmp) { + /* Discard duplicate ModelAction; use action from NodeStack */ + delete curr; + curr = tmp; + } else { + /* + * Perform one-time actions when pushing new ModelAction onto + * NodeStack + */ + curr->create_cv(get_parent_action(curr->get_tid())); + /* Build may_read_from set */ + if (curr->is_read()) + build_reads_from_past(curr); + } + + /* Assign 'creation' parent */ + if (curr->get_type() == THREAD_CREATE) { + Thread *th = (Thread *)curr->get_location(); + th->set_creation(curr); + } + + /* Is there a better interface for setting the next thread rather + than this field/convoluted approach? Perhaps like just returning + it or something? */ + + nextThread = get_next_replay_thread(); + + Node *currnode = curr->get_node(); + Node *parnode = currnode->get_parent(); + + if (!parnode->backtrack_empty()||!currnode->readsfrom_empty()) + if (!next_backtrack || *curr > *next_backtrack) + next_backtrack = curr; + set_backtracking(curr); - currentNode = currentNode->explore_child(curr); - this->action_trace->push_back(curr); + + /* Assign reads_from values */ + /* TODO: perform release/acquire synchronization here; include + * reads_from as ModelAction member? */ + Thread *th = get_thread(curr->get_tid()); + uint64_t value = VALUE_NONE; + if (curr->is_read()) { + const ModelAction *reads_from = curr->get_node()->get_read_from(); + value = reads_from->get_value(); + /* Assign reads_from, perform release/acquire synchronization */ + curr->read_from(reads_from); + r_modification_order(curr,reads_from); + } else if (curr->is_write()) { + w_modification_order(curr); + } + + th->set_return_value(value); + + /* Add action to list last. */ + add_action_to_lists(curr); } -void ModelChecker::print_summary(void) +/** @returns whether the current trace is feasible. */ +bool ModelChecker::isfeasible() { + return !cyclegraph->checkForCycles(); +} + +/** Process a RMW by converting previous read into a RMW. */ +void ModelChecker::process_rmw(ModelAction * act) { + int tid = id_to_int(act->get_tid()); + std::vector *vec = &(*obj_thrd_map)[act->get_location()]; + ASSERT(tid < (int) vec->size()); + ModelAction *lastread=(*vec)[tid].back(); + lastread->upgrade_rmw(act); +} + +/** + * Updates the cyclegraph with the constraints imposed from the current read. + * @param curr The current action. Must be a read. + * @param rf The action that curr reads from. Must be a write. + */ +void ModelChecker::r_modification_order(ModelAction * curr, const ModelAction *rf) { + std::vector *thrd_lists = &(*obj_thrd_map)[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; + for (rit = list->rbegin(); rit != list->rend(); rit++) { + ModelAction *act = *rit; + + /* Include at most one act per-thread that "happens before" curr */ + if (act->happens_before(curr)) { + if (act->is_read()) { + const ModelAction * prevreadfrom=act->get_reads_from(); + if (rf!=prevreadfrom) + cyclegraph->addEdge(rf, prevreadfrom); + } else if (rf!=act) { + cyclegraph->addEdge(rf, act); + } + break; + } + } + } +} + +/** + * Updates the cyclegraph with the constraints imposed from the current write. + * @param curr The current action. Must be a write. + */ +void ModelChecker::w_modification_order(ModelAction * curr) { + std::vector *thrd_lists = &(*obj_thrd_map)[curr->get_location()]; + unsigned int i; + 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->get_location()); + if (last_seq_cst!=NULL) + cyclegraph->addEdge(curr, last_seq_cst); + } + + /* 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 */ + if (act->happens_before(curr)) { + if (act->is_read()) { + cyclegraph->addEdge(curr, act->get_reads_from()); + } else + cyclegraph->addEdge(curr, act); + break; + } + } + } +} + +/** + * 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) { - printf("\n"); - printf("Number of executions: %d\n", num_executions); - printf("Total nodes created: %d\n", TreeNode::getTotalNodes()); + int tid = id_to_int(act->get_tid()); + action_trace->push_back(act); - scheduler->print(); + (*obj_map)[act->get_location()].push_back(act); - print_list(action_trace); - printf("\n"); + std::vector *vec = &(*obj_thrd_map)[act->get_location()]; + if (tid >= (int)vec->size()) + vec->resize(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; } -void ModelChecker::print_list(action_list_t *list) +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)]; +} + +/** + * Gets the last memory_order_seq_cst action (in the total global sequence) + * performed on a particular object (i.e., memory location). + * @param location The object location to check + * @return The last seq_cst action performed + */ +ModelAction * ModelChecker::get_last_seq_cst(const void *location) +{ + action_list_t *list = &(*obj_map)[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()) + 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(); +} + +/** + * 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)[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->get_location()); + /* 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()) + continue; + + /* Don't consider more than one seq_cst write if we are a seq_cst read. */ + if (!act->is_seqcst() || !curr->is_seqcst() || 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; @@ -278,9 +559,23 @@ void ModelChecker::print_list(action_list_t *list) printf("---------------------------------------------------------------------\n"); } +void ModelChecker::print_summary(void) +{ + printf("\n"); + printf("Number of executions: %d\n", num_executions); + printf("Total nodes created: %d\n", node_stack->get_total_nodes()); + + scheduler->print(); + + if (!isfeasible()) + printf("INFEASIBLE EXECUTION!\n"); + print_list(action_trace); + printf("\n"); +} + int ModelChecker::add_thread(Thread *t) { - thread_map[id_to_int(t->get_id())] = t; + (*thread_map)[id_to_int(t->get_id())] = t; scheduler->add_thread(t); return 0; } @@ -290,6 +585,17 @@ void ModelChecker::remove_thread(Thread *t) scheduler->remove_thread(t); } +/** + * Switch from a user-context to the "master thread" context (a.k.a. system + * context). This switch is made with the intention of exploring a particular + * model-checking action (described by a ModelAction object). Must be called + * from a user-thread context. + * @param act The current action that will be explored. May be NULL, although + * there is little reason to switch to the model-checker without an action to + * explore (note: act == NULL is sometimes used as a hack to allow a thread to + * yield control without performing any progress; see thrd_join()). + * @return Return status from the 'swap' call (i.e., success/fail, 0/-1) + */ int ModelChecker::switch_to_master(ModelAction *act) { Thread *old;