a number of fixes to add missing mo_graph edges to speed up detection of infeasible

traces

diff --git a/model.cc b/model.cc
index c01122191d0e712750b382f87b9c0edbfecf9aa2..c9353db71c5bc15c77e802c32285f64f0c697681 100644 (file)
--- a/model.cc
+++ b/model.cc
@@ -934,7 +934,11 @@ bool ModelChecker::r_modification_order(ModelAction *curr, const ModelAction *rf
                                        }
                                } else {
                                        const ModelAction *prevreadfrom = act->get_reads_from();
-                                       if (prevreadfrom != NULL && rf != prevreadfrom) {
+                                       //if the previous read is unresolved, keep going...
+                                       if (prevreadfrom == NULL)
+                                               continue;
+
+                                       if (rf != prevreadfrom) {
                                                mo_graph->addEdge(prevreadfrom, rf);
                                                added = true;
                                        }
@@ -1059,14 +1063,22 @@ bool ModelChecker::w_modification_order(ModelAction *curr)
                        ModelAction *act = *rit;
                        if (act == curr) {
                                /*
-                                * If RMW, we already have all relevant edges,
-                                * so just skip to next thread.
-                                * If normal write, we need to look at earlier
-                                * actions, so continue processing list.
+                                * 1) If RMW and it actually read from something, then we
+                                * already have all relevant edges, so just skip to next
+                                * thread.
+                                * 
+                                * 2) If RMW and it didn't read from anything, we should
+                                * whatever edge we can get to speed up convergence.
+                                *
+                                * 3) If normal write, we need to look at earlier actions, so
+                                * continue processing list.
                                 */
-                               if (curr->is_rmw())
-                                       break;
-                               else
+                               if (curr->is_rmw()) {
+                                       if (curr->get_reads_from()!=NULL)
+                                               break;
+                                       else 
+                                               continue;
+                               } else
                                        continue;
                        }
 
@@ -1083,8 +1095,12 @@ bool ModelChecker::w_modification_order(ModelAction *curr)
                                 */
                                if (act->is_write())
                                        mo_graph->addEdge(act, curr);
-                               else if (act->is_read() && act->get_reads_from() != NULL)
+                               else if (act->is_read()) { 
+                                       //if previous read accessed a null, just keep going
+                                       if (act->get_reads_from() == NULL)
+                                               continue;
                                        mo_graph->addEdge(act->get_reads_from(), curr);
+                               }
                                added = true;
                                break;
                        } else if (act->is_read() && !act->is_synchronizing(curr) &&
@@ -1628,7 +1644,8 @@ void ModelChecker::dumpGraph(char *filename) {
                ModelAction *action=*it;
                if (action->is_read()) {
                        fprintf(file, "N%u [label=\"%u, T%u\"];\n", action->get_seq_number(),action->get_seq_number(), action->get_tid());
-                       fprintf(file, "N%u -> N%u[label=\"rf\", color=red];\n", action->get_seq_number(), action->get_reads_from()->get_seq_number());
+                       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());
                }
                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());