model: handle RMW, unresolved reads in w_modification_order checks

diff --git a/model.cc b/model.cc
index 2be1c82e9861760b321df7a8a54fcfad4ac82dd9..567cbd7a3de983078cfd54677628b34ab60995f3 100644 (file)
--- a/model.cc
+++ b/model.cc
@@ -620,10 +620,16 @@ bool ModelChecker::w_modification_order(ModelAction *curr)
 
                        /* Include at most one act per-thread that "happens before" curr */
                        if (act->happens_before(curr)) {
-                               if (act->is_read())
-                                       mo_graph->addEdge(act->get_reads_from(), curr);
-                               else
+                               /*
+                                * Note: if act is RMW, just add edge:
+                                *   act --mo--> 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)
+                                       mo_graph->addEdge(act->get_reads_from(), curr);
                                added = true;
                                break;
                        } else if (act->is_read() && !act->is_synchronizing(curr) &&