X-Git-Url: http://plrg.eecs.uci.edu/git/?p=model-checker.git;a=blobdiff_plain;f=model.cc;h=1cde35462588ce1a63727937a99872799ac33317;hp=3e54a001a4541b8d5acada69e76c189ff5e82b36;hb=27178b4c4870ab7dcbcfb1135f73a78a19cf4ff8;hpb=50b95c3747f4fe79b2ab1a1a6fc303224e16e418 diff --git a/model.cc b/model.cc index 3e54a00..1cde354 100644 --- a/model.cc +++ b/model.cc @@ -28,6 +28,7 @@ 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()), @@ -216,7 +217,7 @@ void ModelChecker::set_backtracking(ModelAction *act) { ModelAction *prev; Node *node; - Thread *t = get_thread(act->get_tid()); + Thread *t = get_thread(act); prev = get_last_conflict(act); if (prev == NULL) @@ -265,35 +266,38 @@ ModelAction * ModelChecker::get_next_backtrack() * @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) { 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(); curr->read_from(NULL); - Promise *valuepromise = new Promise(curr, value); + Promise *valuepromise = new Promise(curr, value, expiration); promises->push_back(valuepromise); } th->set_return_value(value); @@ -324,6 +328,7 @@ Thread * ModelChecker::check_current_action(ModelAction *curr) second_part_of_rmw = true; delete curr; curr = tmp; + compute_promises(curr); } else { ModelAction *tmp = node_stack->explore_action(curr); if (tmp) { @@ -353,24 +358,27 @@ 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); break; } case THREAD_JOIN: { - Thread *wait, *join; - wait = get_thread(curr->get_tid()); - join = (Thread *)curr->get_location(); - if (!join->is_complete()) - scheduler->wait(wait, 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); + } break; } case THREAD_FINISH: { - Thread *th = get_thread(curr->get_tid()); + Thread *th = get_thread(curr); while (!th->wait_list_empty()) { - Thread *wake = th->pop_wait_list(); + ModelAction *act = th->pop_wait_list(); + Thread *wake = get_thread(act); scheduler->wake(wake); } th->complete(); @@ -384,20 +392,29 @@ Thread * ModelChecker::check_current_action(ModelAction *curr) break; } - Thread *th = get_thread(curr->get_tid()); - bool updated = false; + if (curr->is_read()) { - updated=process_read(curr, th, second_part_of_rmw); + updated = process_read(curr, get_thread(curr), second_part_of_rmw); } if (curr->is_write()) { - bool updated_mod_order=w_modification_order(curr); - bool updated_promises=resolve_promises(curr); - updated=updated_mod_order|updated_promises; + bool updated_mod_order = w_modification_order(curr); + bool updated_promises = resolve_promises(curr); + updated = updated_mod_order || updated_promises; + + if (promises->size()==0) { + for (unsigned int i = 0; isize(); i++) { + struct PendingFutureValue pfv=(*futurevalues)[i]; + if (pfv.act->get_node()->add_future_value(pfv.value, pfv.expiration) && + (!priv->next_backtrack || *pfv.act > *priv->next_backtrack)) + priv->next_backtrack = pfv.act; + } + futurevalues->resize(0); + } mo_graph->commitChanges(); - th->set_return_value(VALUE_NONE); + get_thread(curr)->set_return_value(VALUE_NONE); } if (updated) @@ -407,21 +424,35 @@ Thread * ModelChecker::check_current_action(ModelAction *curr) if (!second_part_of_rmw) add_action_to_lists(curr); + check_curr_backtracking(curr); + + set_backtracking(curr); + + return get_next_thread(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() || - !currnode->promise_empty()) - && (!priv->next_backtrack || - *curr > *priv->next_backtrack)) { + !currnode->read_from_empty() || + !currnode->future_value_empty() || + !currnode->promise_empty()) + && (!priv->next_backtrack || + *curr > *priv->next_backtrack)) { priv->next_backtrack = curr; } +} - set_backtracking(curr); - - return get_next_thread(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; } /** @returns whether the current partial trace must be a prefix of a @@ -432,7 +463,13 @@ bool ModelChecker::isfeasibleprefix() { /** @returns whether the current partial trace is feasible. */ bool ModelChecker::isfeasible() { - return !mo_graph->checkForCycles() && !failed_promise && !too_many_reads; + 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() { + return !mo_graph->checkForCycles() && !failed_promise && !too_many_reads && !promises_expired(); } /** Returns whether the current completed trace is feasible. */ @@ -445,8 +482,10 @@ ModelAction * ModelChecker::process_rmw(ModelAction *act) { int tid = id_to_int(act->get_tid()); ModelAction *lastread = get_last_action(tid); lastread->process_rmw(act); - if (act->is_rmw()) + if (act->is_rmw() && lastread->get_reads_from()!=NULL) { mo_graph->addRMWEdge(lastread->get_reads_from(), lastread); + mo_graph->commitChanges(); + } return lastread; } @@ -482,16 +521,16 @@ void ModelChecker::check_recency(ModelAction *curr, bool already_added) { action_list_t::reverse_iterator rit = list->rbegin(); /* Skip past curr */ - if (!already_added) { + if (already_added) { for (; (*rit) != curr; rit++) ; /* go past curr now */ 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; @@ -504,36 +543,37 @@ 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; /* 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; } } @@ -568,16 +608,19 @@ 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; } } @@ -661,9 +704,11 @@ bool ModelChecker::w_modification_order(ModelAction *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() && act->get_reads_from() != NULL) + if (act->is_write()) { + //RMW shouldn't have an edge to themselves + if (act!=curr) + mo_graph->addEdge(act, curr); + } else if (act->is_read() && act->get_reads_from() != NULL) mo_graph->addEdge(act->get_reads_from(), curr); added = true; break; @@ -677,9 +722,13 @@ bool ModelChecker::w_modification_order(ModelAction *curr) => that read could potentially read from our write. */ - if (act->get_node()->add_future_value(curr->get_value()) && - (!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); + } + } } } } @@ -687,6 +736,28 @@ 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 @@ -711,11 +782,13 @@ bool ModelChecker::w_modification_order(ModelAction *curr) bool ModelChecker::release_seq_head(const ModelAction *rf, std::vector *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()) { @@ -961,11 +1034,15 @@ 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)) { ModelAction *read = promise->get_action(); read->read_from(write); + if (read->is_rmw()) { + mo_graph->addRMWEdge(write, read); + } r_modification_order(read, write); post_r_modification_order(read, write); promises->erase(promises->begin() + promise_index); @@ -973,7 +1050,6 @@ bool ModelChecker::resolve_promises(ModelAction *write) } else promise_index++; } - return resolved; } @@ -1056,7 +1132,7 @@ void ModelChecker::build_reads_from_past(ModelAction *curr) 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) { + 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(); @@ -1163,6 +1239,7 @@ 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())