model: report 'updates' when adding mo_graph edges

The rest of the model checker would like to know if any edges were added. Add a
boolean return value to report this.

diff --git a/model.cc b/model.cc
index bd4496b14b99915b382afaf075ef4958ae9fbe82..fc93296a2524f4d2edc741e36f54dff24eb881e2 100644 (file)
--- a/model.cc
+++ b/model.cc
@@ -387,10 +387,13 @@ ModelAction * ModelChecker::process_rmw(ModelAction *act) {
  * Updates the mo_graph with the constraints imposed from the current read.
  * @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
  */
-void ModelChecker::r_modification_order(ModelAction * curr, const ModelAction *rf) {
+bool ModelChecker::r_modification_order(ModelAction *curr, const ModelAction *rf)
+{
        std::vector<action_list_t> *thrd_lists = obj_thrd_map->get_safe_ptr(curr->get_location());
        unsigned int i;
+       bool added = false;
        ASSERT(curr->is_read());
 
        /* Iterate over all threads */
@@ -405,15 +408,20 @@ void ModelChecker::r_modification_order(ModelAction * curr, const ModelAction *r
                        if (act->happens_before(curr)) {
                                if (act->is_read()) {
                                        const ModelAction *prevreadfrom = act->get_reads_from();
-                                       if (prevreadfrom != NULL && rf != prevreadfrom)
+                                       if (prevreadfrom != NULL && rf != prevreadfrom) {
                                                mo_graph->addEdge(prevreadfrom, rf);
+                                               added = true;
+                                       }
                                } else if (rf != act) {
                                        mo_graph->addEdge(act, rf);
+                                       added = true;
                                }
                                break;
                        }
                }
        }
+
+       return added;
 }
 
 /** Updates the mo_graph with the constraints imposed from the current read. */
@@ -456,18 +464,23 @@ void ModelChecker::post_r_modification_order(ModelAction *curr, const ModelActio
 /**
  * Updates the mo_graph with the constraints imposed from the current write.
  * @param curr The current action. Must be a write.
+ * @return True if modification order edges were added; false otherwise
  */
-void ModelChecker::w_modification_order(ModelAction * curr) {
+bool ModelChecker::w_modification_order(ModelAction *curr)
+{
        std::vector<action_list_t> *thrd_lists = obj_thrd_map->get_safe_ptr(curr->get_location());
        unsigned int i;
+       bool added = false;
        ASSERT(curr->is_write());
 
        if (curr->is_seqcst()) {
                /* We have to at least see the last sequentially consistent write,
                         so we are initialized. */
                ModelAction *last_seq_cst = get_last_seq_cst(curr->get_location());
-               if (last_seq_cst != NULL)
+               if (last_seq_cst != NULL) {
                        mo_graph->addEdge(last_seq_cst, curr);
+                       added = true;
+               }
        }
 
        /* Iterate over all threads */
@@ -484,6 +497,7 @@ void ModelChecker::w_modification_order(ModelAction * curr) {
                                        mo_graph->addEdge(act->get_reads_from(), curr);
                                else
                                        mo_graph->addEdge(act, curr);
+                               added = true;
                                break;
                        } else if (act->is_read() && !act->is_synchronizing(curr) &&
                                                     !act->same_thread(curr)) {
@@ -501,6 +515,8 @@ void ModelChecker::w_modification_order(ModelAction * curr) {
                        }
                }
        }
+
+       return added;
 }
 
 /**

diff --git a/model.h b/model.h
index 0666472d9a2ca9a441db9e3195943ad0b6158e9a..7dc6ed6cb78574596488ecfb53fad221cf1436f1 100644 (file)
--- a/model.h
+++ b/model.h
@@ -103,8 +103,8 @@ private:
        void build_reads_from_past(ModelAction *curr);
        ModelAction * process_rmw(ModelAction *curr);
        void post_r_modification_order(ModelAction *curr, const ModelAction *rf);
-       void r_modification_order(ModelAction *curr, const ModelAction *rf);
-       void w_modification_order(ModelAction *curr);
+       bool r_modification_order(ModelAction *curr, const ModelAction *rf);
+       bool w_modification_order(ModelAction *curr);
        bool release_seq_head(const ModelAction *rf,
                        std::vector<const ModelAction *> *release_heads) const;