model: we only resolve one promise at a time
[c11tester.git] / model.cc
index ced34316234020eca13efcbb7346d1ee523002e9..618b37e00ee86ad5fd03c03216218e7f36ed0067 100644 (file)
--- a/model.cc
+++ b/model.cc
@@ -483,8 +483,16 @@ void ModelChecker::record_stats()
                stats.num_buggy_executions++;
        else if (is_complete_execution())
                stats.num_complete++;
-       else
+       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());
+       }
 }
 
 /** @brief Print execution stats */
@@ -871,6 +879,16 @@ bool ModelChecker::process_read(ModelAction *curr)
                        updated |= r_status;
                        break;
                }
+               case READ_FROM_PROMISE: {
+                       Promise *promise = curr->get_node()->get_read_from_promise();
+                       promise->add_reader(curr);
+                       value = promise->get_value();
+                       curr->set_read_from_promise(promise);
+                       mo_graph->startChanges();
+                       updated = r_modification_order(curr, promise);
+                       mo_graph->commitChanges();
+                       break;
+               }
                case READ_FROM_FUTURE: {
                        /* Read from future value */
                        struct future_value fv = node->get_future_value();
@@ -1010,7 +1028,7 @@ void ModelChecker::add_future_value(const ModelAction *writer, ModelAction *read
                        write_thread = write_thread->get_parent();
 
                struct future_value fv = {
-                       writer->get_value(),
+                       writer->get_write_value(),
                        writer->get_seq_number() + params.maxfuturedelay,
                        write_thread->get_id(),
                };
@@ -1027,7 +1045,11 @@ void ModelChecker::add_future_value(const ModelAction *writer, ModelAction *read
 bool ModelChecker::process_write(ModelAction *curr)
 {
        bool updated_mod_order = w_modification_order(curr);
-       bool updated_promises = resolve_promises(curr);
+       int promise_idx = get_promise_to_resolve(curr);
+       bool updated_promises = false;
+
+       if (promise_idx >= 0)
+               updated_promises = resolve_promise(curr, promise_idx);
 
        if (promises->size() == 0) {
                for (unsigned int i = 0; i < futurevalues->size(); i++) {
@@ -1312,8 +1334,9 @@ bool ModelChecker::initialize_curr_action(ModelAction **curr)
  */
 bool ModelChecker::read_from(ModelAction *act, const ModelAction *rf)
 {
+       ASSERT(rf);
        act->set_read_from(rf);
-       if (rf != NULL && act->is_acquire()) {
+       if (act->is_acquire()) {
                rel_heads_list_t release_heads;
                get_release_seq_heads(act, act, &release_heads);
                int num_heads = release_heads.size();
@@ -1339,14 +1362,19 @@ void ModelChecker::thread_blocking_check_promises(Thread *blocker, Thread *waiti
 {
        for (unsigned int i = 0; i < promises->size(); i++) {
                Promise *promise = (*promises)[i];
-               ModelAction *reader = promise->get_action();
-               if (reader->get_tid() != blocker->get_id())
-                       continue;
                if (!promise->thread_is_available(waiting->get_id()))
                        continue;
-               if (promise->eliminate_thread(waiting->get_id())) {
-                       /* Promise has failed */
-                       priv->failed_promise = true;
+               for (unsigned int j = 0; j < promise->get_num_readers(); j++) {
+                       ModelAction *reader = promise->get_reader(j);
+                       if (reader->get_tid() != blocker->get_id())
+                               continue;
+                       if (promise->eliminate_thread(waiting->get_id())) {
+                               /* Promise has failed */
+                               priv->failed_promise = true;
+                       } else {
+                               /* Only eliminate the 'waiting' thread once */
+                               return;
+                       }
                }
        }
 }
@@ -2428,42 +2456,49 @@ ClockVector * ModelChecker::get_cv(thread_id_t tid) const
 }
 
 /**
- * Resolve a set of Promises with a current write. The set is provided in the
- * Node corresponding to @a write.
+ * @brief Find the promise, if any to resolve for the current action
+ * @param curr The current ModelAction. Should be a write.
+ * @return The (non-negative) index for the Promise to resolve, if any;
+ * otherwise -1
+ */
+int ModelChecker::get_promise_to_resolve(const ModelAction *curr) const
+{
+       for (unsigned int i = 0; i < promises->size(); i++)
+               if (curr->get_node()->get_promise(i))
+                       return i;
+       return -1;
+}
+
+/**
+ * Resolve a Promise with a current write.
  * @param write The ModelAction that is fulfilling Promises
- * @return True if promises were resolved; false otherwise
+ * @param promise_idx The index corresponding to the promise
+ * @return True if the Promise was successfully resolved; false otherwise
  */
-bool ModelChecker::resolve_promises(ModelAction *write)
+bool ModelChecker::resolve_promise(ModelAction *write, unsigned int promise_idx)
 {
-       bool haveResolved = false;
        std::vector< ModelAction *, ModelAlloc<ModelAction *> > actions_to_check;
-       promise_list_t mustResolve, resolved;
+       promise_list_t mustResolve;
+       Promise *promise = (*promises)[promise_idx];
 
-       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_from(read, write);
-                       //Make sure the promise's value matches the write's value
-                       ASSERT(promise->is_compatible(write));
-                       mo_graph->resolvePromise(promise, write, &mustResolve);
+       for (unsigned int i = 0; i < promise->get_num_readers(); i++) {
+               ModelAction *read = promise->get_reader(i);
+               read_from(read, write);
+               actions_to_check.push_back(read);
+       }
+       /* Make sure the promise's value matches the write's value */
+       ASSERT(promise->is_compatible(write) && promise->same_value(write));
+       mo_graph->resolvePromise(promise, write, &mustResolve);
 
-                       resolved.push_back(promise);
-                       promises->erase(promises->begin() + promise_index);
-                       actions_to_check.push_back(read);
+       promises->erase(promises->begin() + promise_idx);
 
-                       haveResolved = true;
-               } else
-                       promise_index++;
-       }
+       /** @todo simplify the 'mustResolve' stuff */
+       ASSERT(mustResolve.size() <= 1);
+
+       if (!mustResolve.empty() && mustResolve[0] != promise)
+               priv->failed_promise = true;
+       delete promise;
 
-       for (unsigned int i = 0; i < mustResolve.size(); i++) {
-               if (std::find(resolved.begin(), resolved.end(), mustResolve[i])
-                               == resolved.end())
-                       priv->failed_promise = true;
-       }
-       for (unsigned int i = 0; i < resolved.size(); i++)
-               delete resolved[i];
        //Check whether reading these writes has made threads unable to
        //resolve promises
 
@@ -2472,7 +2507,7 @@ bool ModelChecker::resolve_promises(ModelAction *write)
                mo_check_promises(read, true);
        }
 
-       return haveResolved;
+       return true;
 }
 
 /**
@@ -2485,14 +2520,20 @@ 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();
-               ASSERT(act->is_read());
-               if (!act->happens_before(curr) &&
-                               !act->could_synchronize_with(curr) &&
-                               promise->is_compatible(curr) &&
-                               promise->get_value() == curr->get_value()) {
-                       curr->get_node()->set_promise(i, act->is_rmw());
+               if (!promise->is_compatible(curr) || !promise->same_value(curr))
+                       continue;
+
+               bool satisfy = true;
+               for (unsigned int j = 0; j < promise->get_num_readers(); j++) {
+                       const ModelAction *act = promise->get_reader(j);
+                       if (act->happens_before(curr) ||
+                                       act->could_synchronize_with(curr)) {
+                               satisfy = false;
+                               break;
+                       }
                }
+               if (satisfy)
+                       curr->get_node()->set_promise(i);
        }
 }
 
@@ -2501,13 +2542,17 @@ void ModelChecker::check_promises(thread_id_t tid, ClockVector *old_cv, ClockVec
 {
        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)) {
-                       if (promise->eliminate_thread(tid)) {
-                               //Promise has failed
-                               priv->failed_promise = true;
-                               return;
+               if (!promise->thread_is_available(tid))
+                       continue;
+               for (unsigned int j = 0; j < promise->get_num_readers(); j++) {
+                       const ModelAction *act = promise->get_reader(j);
+                       if ((!old_cv || !old_cv->synchronized_since(act)) &&
+                                       merge_cv->synchronized_since(act)) {
+                               if (promise->eliminate_thread(tid)) {
+                                       /* Promise has failed */
+                                       priv->failed_promise = true;
+                                       return;
+                               }
                        }
                }
        }
@@ -2544,15 +2589,20 @@ void ModelChecker::mo_check_promises(const ModelAction *act, bool is_read_check)
 
        for (unsigned int i = 0; i < promises->size(); i++) {
                Promise *promise = (*promises)[i];
-               const ModelAction *pread = promise->get_action();
 
                // Is this promise on the same location?
-               if (!pread->same_var(write))
+               if (!promise->same_location(write))
                        continue;
 
-               if (pread->happens_before(act) && mo_graph->checkPromise(write, promise)) {
-                       priv->failed_promise = true;
-                       return;
+               for (unsigned int j = 0; j < promise->get_num_readers(); j++) {
+                       const ModelAction *pread = promise->get_reader(j);
+                       if (!pread->happens_before(act))
+                              continue;
+                       if (mo_graph->checkPromise(write, promise)) {
+                               priv->failed_promise = true;
+                               return;
+                       }
+                       break;
                }
 
                // Don't do any lookups twice for the same thread
@@ -2647,15 +2697,13 @@ void ModelChecker::build_may_read_from(ModelAction *curr)
        /* Inherit existing, promised future values */
        for (i = 0; i < promises->size(); i++) {
                const Promise *promise = (*promises)[i];
-               const ModelAction *promise_read = promise->get_action();
+               const ModelAction *promise_read = promise->get_reader(0);
                if (promise_read->same_var(curr)) {
                        /* Only add feasible future-values */
                        mo_graph->startChanges();
                        r_modification_order(curr, promise);
-                       if (!is_infeasible()) {
-                               const struct future_value fv = promise->get_fv();
-                               curr->get_node()->add_future_value(fv);
-                       }
+                       if (!is_infeasible())
+                               curr->get_node()->add_read_from_promise(promise_read);
                        mo_graph->rollbackChanges();
                }
        }
@@ -2732,17 +2780,28 @@ void ModelChecker::dumpGraph(char *filename) const
        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=\"N%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());
+               ModelAction *act = *it;
+               if (act->is_read()) {
+                       mo_graph->dot_print_node(file, act);
+                       if (act->get_reads_from())
+                               mo_graph->dot_print_edge(file,
+                                               act->get_reads_from(),
+                                               act,
+                                               "label=\"rf\", color=red, weight=2");
+                       else
+                               mo_graph->dot_print_edge(file,
+                                               act->get_reads_from_promise(),
+                                               act,
+                                               "label=\"rf\", color=red");
                }
-               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());
+               if (thread_array[act->get_tid()]) {
+                       mo_graph->dot_print_edge(file,
+                                       thread_array[id_to_int(act->get_tid())],
+                                       act,
+                                       "label=\"sb\", color=blue, weight=400");
                }
 
-               thread_array[action->get_tid()] = action;
+               thread_array[act->get_tid()] = act;
        }
        fprintf(file, "}\n");
        model_free(thread_array);
@@ -2762,9 +2821,11 @@ void ModelChecker::print_summary() const
 #endif
 
        model_print("Execution %d:", stats.num_total);
-       if (isfeasibleprefix())
+       if (isfeasibleprefix()) {
+               if (scheduler->all_threads_sleeping())
+                       model_print(" SLEEP-SET REDUNDANT");
                model_print("\n");
-       else
+       else
                print_infeasibility(" INFEASIBLE");
        print_list(action_trace);
        model_print("\n");
@@ -2810,6 +2871,26 @@ Thread * ModelChecker::get_thread(const ModelAction *act) const
        return get_thread(act->get_tid());
 }
 
+/**
+ * @brief Get a Promise's "promise number"
+ *
+ * A "promise number" is an index number that is unique to a promise, valid
+ * only for a specific snapshot of an execution trace. Promises may come and go
+ * as they are generated an resolved, so an index only retains meaning for the
+ * current snapshot.
+ *
+ * @param promise The Promise to check
+ * @return The promise index, if the promise still is valid; otherwise -1
+ */
+int ModelChecker::get_promise_number(const Promise *promise) const
+{
+       for (unsigned int i = 0; i < promises->size(); i++)
+               if ((*promises)[i] == promise)
+                       return i;
+       /* Not found */
+       return -1;
+}
+
 /**
  * @brief Check if a Thread is currently enabled
  * @param t The Thread to check