X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=model.cc;h=38c5d4a9396f82bde9b8341fac00f8b2d8dc63a6;hb=3864415594472a6a9b2b09bb0e0f846f056b7a47;hp=cc464a2bcc5b76b933d8769ba450486b4804edbf;hpb=a0562e0739fd643fdb2108f784f4722482ea5a4f;p=model-checker.git diff --git a/model.cc b/model.cc index cc464a2..38c5d4a 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()), @@ -28,6 +29,7 @@ ModelChecker::ModelChecker(struct model_params params) : obj_map(new HashTable()), obj_thrd_map(new HashTable, uintptr_t, 4 >()), promises(new std::vector()), + futurevalues(new std::vector()), lazy_sync_with_release(new HashTable, uintptr_t, 4>()), thrd_last_action(new std::vector(1)), node_stack(new NodeStack()), @@ -173,6 +175,8 @@ bool ModelChecker::next_execution() DBG(); num_executions++; + if (isfinalfeasible()) + num_feasible_executions++; if (isfinalfeasible() || DBG_ENABLED()) print_summary(); @@ -261,37 +265,37 @@ 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) { + 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(); - /* Assign reads_from, perform release/acquire synchronization */ - curr->read_from(reads_from); + bool r_status = false; + if (!second_part_of_rmw) { check_recency(curr,false); + r_status = r_modification_order(curr, reads_from); } - bool r_status=r_modification_order(curr,reads_from); - if (!second_part_of_rmw&&!isfeasible()&&(curr->get_node()->increment_read_from()||!curr->get_node()->future_value_empty())) { + 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; + too_many_reads = false; continue; } + curr->read_from(reads_from); mo_graph->commitChanges(); updated |= r_status; - } else { + } 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(); @@ -299,11 +303,36 @@ 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 @@ -357,7 +386,7 @@ Thread * ModelChecker::check_current_action(ModelAction *curr) } /* Thread specific actions */ - switch(curr->get_type()) { + switch (curr->get_type()) { case THREAD_CREATE: { Thread *th = (Thread *)curr->get_location(); th->set_creation(curr); @@ -391,31 +420,43 @@ Thread * ModelChecker::check_current_action(ModelAction *curr) break; } - Thread *th = get_thread(curr); + work_queue_t work_queue(1, CheckCurrWorkEntry(curr)); - bool updated = false; - if (curr->is_read()) { - updated=process_read(curr, th, 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_mod_order|updated_promises; + 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(); - th->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) add_action_to_lists(curr); check_curr_backtracking(curr); - + set_backtracking(curr); return get_next_thread(curr); @@ -424,7 +465,7 @@ Thread * ModelChecker::check_current_action(ModelAction *curr) 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() || @@ -435,7 +476,6 @@ void ModelChecker::check_curr_backtracking(ModelAction * curr) { } } - bool ModelChecker::promises_expired() { for (unsigned int promise_index = 0; promise_index < promises->size(); promise_index++) { Promise *promise = (*promises)[promise_index]; @@ -454,11 +494,30 @@ bool ModelChecker::isfeasibleprefix() { /** @returns whether the current partial trace is feasible. */ bool ModelChecker::isfeasible() { + return !mo_graph->checkForRMWViolation() && isfeasibleotherthanRMW(); +} + +/** @returns 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 (promises_expired()) + DEBUG("Infeasible: promises expired\n"); + } return !mo_graph->checkForCycles() && !failed_promise && !too_many_reads && !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; } @@ -513,9 +572,9 @@ void ModelChecker::check_recency(ModelAction *curr, bool already_added) { rit++; } - action_list_t::reverse_iterator ritcopy=rit; + action_list_t::reverse_iterator ritcopy = rit; //See if we have enough reads from the same value - int count=0; + int count = 0; for (; count < params.maxreads; rit++,count++) { if (rit==list->rend()) return; @@ -528,9 +587,9 @@ void ModelChecker::check_recency(ModelAction *curr, bool already_added) { return; } - for (int i=0;iget_node()->get_read_from_size();i++) { + for (int i = 0; iget_node()->get_read_from_size(); i++) { //Get write - const ModelAction * write=curr->get_node()->get_read_from_at(i); + const ModelAction * write = curr->get_node()->get_read_from_at(i); //Need a different write if (write==curr->get_reads_from()) continue; @@ -538,27 +597,27 @@ void ModelChecker::check_recency(ModelAction *curr, bool already_added) { /* Test to see whether this is a feasible write to read from*/ mo_graph->startChanges(); r_modification_order(curr, write); - bool feasiblereadfrom=isfeasible(); + bool feasiblereadfrom = isfeasible(); mo_graph->rollbackChanges(); if (!feasiblereadfrom) continue; - rit=ritcopy; + rit = ritcopy; - bool feasiblewrite=true; + bool feasiblewrite = true; //new we need to see if this write works for everyone - for (int loop=count;loop>0;loop--,rit++) { + 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++) { + 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; + foundvalue = true; break; } } if (!foundvalue) { - feasiblewrite=false; + feasiblewrite = false; break; } } @@ -571,7 +630,18 @@ 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 @@ -593,16 +663,19 @@ bool ModelChecker::r_modification_order(ModelAction *curr, const ModelAction *rf /* Include at most one act per-thread that "happens before" curr */ if (act->happens_before(curr)) { - if (act->is_read()) { + if (act->is_write()) { + if (rf != act && act != curr) { + mo_graph->addEdge(act, rf); + added = true; + } + } else { const ModelAction *prevreadfrom = act->get_reads_from(); if (prevreadfrom != NULL && rf != prevreadfrom) { mo_graph->addEdge(prevreadfrom, rf); added = true; } - } else if (rf != act) { - mo_graph->addEdge(act, rf); - added = true; } + break; } } @@ -611,7 +684,22 @@ 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()); @@ -650,6 +738,23 @@ 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 */ @@ -704,9 +809,13 @@ bool ModelChecker::w_modification_order(ModelAction *curr) => that read could potentially read from our write. */ - if (isfeasible() && act->get_node()->add_future_value(curr->get_value(), curr->get_seq_number()+params.maxfuturedelay) && - (!priv->next_backtrack || *act > *priv->next_backtrack)) - priv->next_backtrack = act; + 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); + } + } } } } @@ -714,6 +823,28 @@ bool ModelChecker::w_modification_order(ModelAction *curr) 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; +} + /** * Finds the head(s) of the release sequence(s) containing a given ModelAction. * The ModelAction under consideration is expected to be taking part in @@ -736,13 +867,15 @@ bool ModelChecker::w_modification_order(ModelAction *curr) * false otherwise */ bool ModelChecker::release_seq_head(const ModelAction *rf, - std::vector *release_heads) const + std::vector< const ModelAction *, MyAlloc > *release_heads) const { - ASSERT(rf->is_write()); if (!rf) { /* read from future: need to settle this later */ return false; /* incomplete */ } + + ASSERT(rf->is_write()); + if (rf->is_release()) release_heads->push_back(rf); if (rf->is_rmw()) { @@ -840,7 +973,7 @@ bool ModelChecker::release_seq_head(const ModelAction *rf, * @see ModelChecker::release_seq_head */ void ModelChecker::get_release_seq_heads(ModelAction *act, - std::vector *release_heads) + std::vector< const ModelAction *, MyAlloc > *release_heads) { const ModelAction *rf = act->get_reads_from(); bool complete; @@ -862,9 +995,12 @@ 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); @@ -876,7 +1012,7 @@ bool ModelChecker::resolve_release_sequences(void *location) while (it != list->end()) { ModelAction *act = *it; const ModelAction *rf = act->get_reads_from(); - std::vector release_heads; + std::vector< const ModelAction *, MyAlloc > release_heads; bool complete; complete = release_seq_head(rf, &release_heads); for (unsigned int i = 0; i < release_heads.size(); i++) { @@ -887,14 +1023,18 @@ 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) { @@ -988,6 +1128,7 @@ ClockVector * ModelChecker::get_cv(thread_id_t tid) bool ModelChecker::resolve_promises(ModelAction *write) { bool resolved = false; + 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)) { @@ -996,14 +1137,17 @@ 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; } else promise_index++; } - return resolved; } @@ -1136,9 +1280,15 @@ 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%u",num_executions); + mo_graph->dumpGraphToFile(buffername); +#endif if (!isfinalfeasible()) printf("INFEASIBLE EXECUTION!\n"); @@ -1193,6 +1343,7 @@ bool ModelChecker::take_step() { 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())