model: add promise-node edges for 'read' actions
[model-checker.git] / model.cc
index 40b25d0d635a32a5fdd2832001c638c3ee1986fc..15f1831627e0621896fadc3638ec27e6814cfc07 100644 (file)
--- a/model.cc
+++ b/model.cc
@@ -721,7 +721,6 @@ bool ModelChecker::process_read(ModelAction *curr, bool second_part_of_rmw)
                                r_status = r_modification_order(curr, reads_from);
                        }
 
-
                        if (!second_part_of_rmw && is_infeasible() && (curr->get_node()->increment_read_from() || curr->get_node()->increment_future_value())) {
                                mo_graph->rollbackChanges();
                                priv->too_many_reads = false;
@@ -736,9 +735,13 @@ bool ModelChecker::process_read(ModelAction *curr, bool second_part_of_rmw)
                } else if (!second_part_of_rmw) {
                        /* Read from future value */
                        struct future_value fv = curr->get_node()->get_future_value();
+                       Promise *promise = new Promise(curr, fv);
                        value = fv.value;
-                       curr->set_read_from(NULL);
-                       promises->push_back(new Promise(curr, fv));
+                       curr->set_read_from_promise(promise);
+                       promises->push_back(promise);
+                       mo_graph->startChanges();
+                       updated = r_modification_order(curr, promise);
+                       mo_graph->commitChanges();
                }
                get_thread(curr)->set_return_value(value);
                return updated;
@@ -856,11 +859,19 @@ void ModelChecker::add_future_value(const ModelAction *writer, ModelAction *read
 {
        /* Do more ambitious checks now that mo is more complete */
        if (mo_may_allow(writer, reader)) {
+               Node *node = reader->get_node();
+
+               /* Find an ancestor thread which exists at the time of the reader */
+               Thread *write_thread = get_thread(writer);
+               while (id_to_int(write_thread->get_id()) >= node->get_num_threads())
+                       write_thread = write_thread->get_parent();
+
                struct future_value fv = {
                        writer->get_value(),
                        writer->get_seq_number() + params.maxfuturedelay,
+                       write_thread->get_id(),
                };
-               if (reader->get_node()->add_future_value(fv))
+               if (node->add_future_value(fv))
                        set_latest_backtrack(reader);
        }
 }
@@ -959,6 +970,12 @@ bool ModelChecker::process_thread_action(ModelAction *curr)
        case THREAD_CREATE: {
                Thread *th = curr->get_thread_operand();
                th->set_creation(curr);
+               /* Promises can be satisfied by children */
+               for (unsigned int i = 0; i < promises->size(); i++) {
+                       Promise *promise = (*promises)[i];
+                       if (promise->thread_is_available(curr->get_tid()))
+                               promise->add_thread(th->get_id());
+               }
                break;
        }
        case THREAD_JOIN: {
@@ -975,6 +992,13 @@ bool ModelChecker::process_thread_action(ModelAction *curr)
                        scheduler->wake(get_thread(act));
                }
                th->complete();
+               /* Completed thread can't satisfy promises */
+               for (unsigned int i = 0; i < promises->size(); i++) {
+                       Promise *promise = (*promises)[i];
+                       if (promise->thread_is_available(th->get_id()))
+                               if (promise->eliminate_thread(th->get_id()))
+                                       priv->failed_promise = true;
+               }
                updated = true; /* trigger rel-seq checks */
                break;
        }
@@ -1283,8 +1307,14 @@ ModelAction * ModelChecker::check_current_action(ModelAction *curr)
 
                        if (act->is_read()) {
                                const ModelAction *rf = act->get_reads_from();
-                               if (rf != NULL && r_modification_order(act, rf))
-                                       updated = true;
+                               const Promise *promise = act->get_reads_from_promise();
+                               if (rf) {
+                                       if (r_modification_order(act, rf))
+                                               updated = true;
+                               } else if (promise) {
+                                       if (r_modification_order(act, promise))
+                                               updated = true;
+                               }
                        }
                        if (act->is_write()) {
                                if (w_modification_order(act))
@@ -1351,8 +1381,6 @@ void ModelChecker::print_infeasibility(const char *prefix) const
 {
        char buf[100];
        char *ptr = buf;
-       if (mo_graph->checkForRMWViolation())
-               ptr += sprintf(ptr, "[RMW atomicity]");
        if (mo_graph->checkForCycles())
                ptr += sprintf(ptr, "[mo cycle]");
        if (priv->failed_promise)
@@ -1386,21 +1414,10 @@ bool ModelChecker::is_feasible_prefix_ignore_relseq() const
  */
 bool ModelChecker::is_infeasible() const
 {
-       return mo_graph->checkForRMWViolation() || is_infeasible_ignoreRMW();
-}
-
-/**
- * Check If the current partial trace is infeasible, while ignoring
- * infeasibility related to 2 RMW's reading from the same store. It does not
- * check end-of-execution feasibility.
- * @see ModelChecker::is_infeasible
- * @return whether the current partial trace is infeasible, ignoring multiple
- * RMWs reading from the same store.
- * */
-bool ModelChecker::is_infeasible_ignoreRMW() const
-{
-       return mo_graph->checkForCycles() || priv->failed_promise ||
-               priv->too_many_reads || priv->bad_synchronization ||
+       return mo_graph->checkForCycles() ||
+               priv->failed_promise ||
+               priv->too_many_reads ||
+               priv->bad_synchronization ||
                promises_expired();
 }
 
@@ -1513,7 +1530,7 @@ void ModelChecker::check_recency(ModelAction *curr, const ModelAction *rf)
  * read.
  *
  * Basic idea is the following: Go through each other thread and find
- * the lastest action that happened before our read.  Two cases:
+ * the last 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.
@@ -1522,10 +1539,11 @@ void ModelChecker::check_recency(ModelAction *curr, const ModelAction *rf)
  * 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.
+ * @param rf The ModelAction or Promise 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)
+template <typename rf_type>
+bool ModelChecker::r_modification_order(ModelAction *curr, const rf_type *rf)
 {
        std::vector<action_list_t> *thrd_lists = get_safe_ptr_vect_action(obj_thrd_map, curr->get_location());
        unsigned int i;
@@ -1553,7 +1571,7 @@ bool ModelChecker::r_modification_order(ModelAction *curr, const ModelAction *rf
                for (rit = list->rbegin(); rit != list->rend(); rit++) {
                        ModelAction *act = *rit;
 
-                       if (act->is_write() && act != rf && act != curr) {
+                       if (act->is_write() && !act->equals(rf) && act != curr) {
                                /* C++, Section 29.3 statement 5 */
                                if (curr->is_seqcst() && last_sc_fence_thread_local &&
                                                *act < *last_sc_fence_thread_local) {
@@ -1583,7 +1601,7 @@ bool ModelChecker::r_modification_order(ModelAction *curr, const ModelAction *rf
                         */
                        if (act->happens_before(curr) && act != curr) {
                                if (act->is_write()) {
-                                       if (rf != act) {
+                                       if (!act->equals(rf)) {
                                                mo_graph->addEdge(act, rf);
                                                added = true;
                                        }
@@ -1593,7 +1611,7 @@ bool ModelChecker::r_modification_order(ModelAction *curr, const ModelAction *rf
                                        if (prevreadfrom == NULL)
                                                continue;
 
-                                       if (rf != prevreadfrom) {
+                                       if (!prevreadfrom->equals(rf)) {
                                                mo_graph->addEdge(prevreadfrom, rf);
                                                added = true;
                                        }
@@ -1789,10 +1807,10 @@ bool ModelChecker::w_modification_order(ModelAction *curr)
 
                                 */
                                if (thin_air_constraint_may_allow(curr, act)) {
-                                       if (!is_infeasible() ||
-                                                       (curr->is_rmw() && act->is_rmw() && curr->get_reads_from() == act->get_reads_from() && !is_infeasible_ignoreRMW())) {
+                                       if (!is_infeasible())
                                                futurevalues->push_back(PendingFutureValue(curr, act));
-                                       }
+                                       else if (curr->is_rmw() && act->is_rmw() && curr->get_reads_from() && curr->get_reads_from() == act->get_reads_from())
+                                               add_future_value(curr, act);
                                }
                        }
                }
@@ -2331,7 +2349,7 @@ bool ModelChecker::resolve_promises(ModelAction *write)
                        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);
+                       delete promise;
 
                        promises->erase(promises->begin() + promise_index);
                        actions_to_check.push_back(read);
@@ -2466,7 +2484,7 @@ void ModelChecker::mo_check_promises(thread_id_t tid, const ModelAction *write,
                }
 
                // Don't do any lookups twice for the same thread
-               if (promise->thread_is_eliminated(tid))
+               if (!promise->thread_is_available(tid))
                        continue;
 
                if (promise->get_write() && mo_graph->checkReachable(promise->get_write(), write)) {
@@ -2639,7 +2657,6 @@ void ModelChecker::dumpGraph(char *filename) const
 void ModelChecker::print_summary() const
 {
 #if SUPPORT_MOD_ORDER_DUMP
-       scheduler->print();
        char buffername[100];
        sprintf(buffername, "exec%04u", stats.num_total);
        mo_graph->dumpGraphToFile(buffername);