fix for horrible bug... turns out that we could generate an infinite set of bad...

fix--don't send future values backwards until all of your promises are resolved...

diff --git a/model.cc b/model.cc
index 015ca16796f9b9fdc9bae0ea0ff2b76dfdee4e7f..795c4a99fea347b1d610c62df8172c55c447f91d 100644 (file)
--- a/model.cc
+++ b/model.cc
@@ -28,6 +28,7 @@ ModelChecker::ModelChecker(struct model_params params) :
        obj_map(new HashTable<const void *, action_list_t, uintptr_t, 4>()),
        obj_thrd_map(new HashTable<void *, std::vector<action_list_t>, uintptr_t, 4 >()),
        promises(new std::vector<Promise *>()),
+       futurevalues(new std::vector<struct PendingFutureValue>()),
        lazy_sync_with_release(new HashTable<void *, std::list<ModelAction *>, uintptr_t, 4>()),
        thrd_last_action(new std::vector<ModelAction *>(1)),
        node_stack(new NodeStack()),
@@ -404,6 +405,16 @@ Thread * ModelChecker::check_current_action(ModelAction *curr)
                bool updated_promises=resolve_promises(curr);
                updated=updated_mod_order|updated_promises;
 
+               if (promises->size()==0) {
+                       for(unsigned int i=0;i<futurevalues->size();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);
        }
@@ -714,9 +725,8 @@ bool ModelChecker::w_modification_order(ModelAction *curr)
                                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())) {
-                                               if (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;
+                                               struct PendingFutureValue pfv={curr->get_value(),curr->get_seq_number()+params.maxfuturedelay,act};
+                                               futurevalues->push_back(pfv);
                                        }
                                }
                        }

diff --git a/model.h b/model.h
index fec8d1f1ea55bf331017f9817515cae7e0d93c34..9afe642aea2ad76152556c2fd6dc15f29e09b488 100644 (file)
--- a/model.h
+++ b/model.h
@@ -32,6 +32,12 @@ struct model_params {
        int maxfuturedelay;
 };
 
+struct PendingFutureValue {
+       uint64_t value;
+       modelclock_t expiration;
+       ModelAction * act;
+};
+
 /**
  * Structure for holding small ModelChecker members that should be snapshotted
  */
@@ -143,6 +149,7 @@ private:
 
        HashTable<void *, std::vector<action_list_t>, uintptr_t, 4 > *obj_thrd_map;
        std::vector<Promise *> *promises;
+       std::vector<struct PendingFutureValue> *futurevalues;
 
        /**
         * Collection of lists of objects that might synchronize with one or