model: totally destroy 'curr' within initialize_curr_action()

We don't really want 'curr' and 'newcurr' to hang around together. So
convert initialize_curr_action() to have two "return" parameters; it
overwrites the 'curr' pointer as a return value and it returns a status
boolean to show that it overwrote it. This may help prevent some future
bugs.

diff --git a/model.cc b/model.cc
index 775b796f167d68ee8394a0e828b0791e122a4937..7181f86977688054159da03d0c3a7921ce23c958 100644 (file)
--- a/model.cc
+++ b/model.cc
@@ -744,41 +744,46 @@ void ModelChecker::process_relseq_fixup(ModelAction *curr, work_queue_t *work_qu
  * initializing clock vectors, and computing the promises to fulfill.
  *
  * @param curr The current action, as passed from the user context; may be
- * freed/invalidated after the execution of this function
- * @return The current action, as processed by the ModelChecker. Is only the
- * same as the parameter @a curr if this is a newly-explored action.
+ * freed/invalidated after the execution of this function, with a different
+ * action "returned" its place (pass-by-reference)
+ * @return True if curr is a newly-explored action; false otherwise
  */
-ModelAction * ModelChecker::initialize_curr_action(ModelAction *curr)
+bool ModelChecker::initialize_curr_action(ModelAction **curr)
 {
        ModelAction *newcurr;
 
-       if (curr->is_rmwc() || curr->is_rmw()) {
-               newcurr = process_rmw(curr);
-               delete curr;
+       if ((*curr)->is_rmwc() || (*curr)->is_rmw()) {
+               newcurr = process_rmw(*curr);
+               delete *curr;
 
                if (newcurr->is_rmw())
                        compute_promises(newcurr);
-               return newcurr;
+
+               *curr = newcurr;
+               return false;
        }
 
-       curr->set_seq_number(get_next_seq_num());
+       (*curr)->set_seq_number(get_next_seq_num());
 
-       newcurr = node_stack->explore_action(curr, scheduler->get_enabled());
+       newcurr = node_stack->explore_action(*curr, scheduler->get_enabled());
        if (newcurr) {
                /* First restore type and order in case of RMW operation */
-               if (curr->is_rmwr())
-                       newcurr->copy_typeandorder(curr);
+               if ((*curr)->is_rmwr())
+                       newcurr->copy_typeandorder(*curr);
 
-               ASSERT(curr->get_location() == newcurr->get_location());
-               newcurr->copy_from_new(curr);
+               ASSERT((*curr)->get_location() == newcurr->get_location());
+               newcurr->copy_from_new(*curr);
 
                /* Discard duplicate ModelAction; use action from NodeStack */
-               delete curr;
+               delete *curr;
 
                /* Always compute new clock vector */
                newcurr->create_cv(get_parent_action(newcurr->get_tid()));
+
+               *curr = newcurr;
+               return false; /* Action was explored previously */
        } else {
-               newcurr = curr;
+               newcurr = *curr;
 
                /* Always compute new clock vector */
                newcurr->create_cv(get_parent_action(newcurr->get_tid()));
@@ -795,8 +800,8 @@ ModelAction * ModelChecker::initialize_curr_action(ModelAction *curr)
                else if (newcurr->is_notify_one()) {
                        newcurr->get_node()->set_misc_max(condvar_waiters_map->get_safe_ptr(newcurr->get_location())->size());
                }
+               return true; /* This was a new ModelAction */
        }
-       return newcurr;
 }
 
 /**
@@ -854,18 +859,17 @@ Thread * ModelChecker::check_current_action(ModelAction *curr)
                return get_next_thread(NULL);
        }
 
-       ModelAction *newcurr = initialize_curr_action(curr);
+       bool newly_explored = initialize_curr_action(&curr);
 
-       wake_up_sleeping_actions(newcurr);
+       wake_up_sleeping_actions(curr);
 
        /* Add the action to lists before any other model-checking tasks */
        if (!second_part_of_rmw)
-               add_action_to_lists(newcurr);
+               add_action_to_lists(curr);
 
        /* Build may_read_from set for newly-created actions */
-       if (curr == newcurr && curr->is_read())
+       if (newly_explored && curr->is_read())
                build_reads_from_past(curr);
-       curr = newcurr;
 
        /* Initialize work_queue with the "current action" work */
        work_queue_t work_queue(1, CheckCurrWorkEntry(curr));

diff --git a/model.h b/model.h
index d0043a1f88b1990de8e0fcdee27e21baa387ccd7..8ff9d375838b193bec751f9b7f0d419a89f07a8d 100644 (file)
--- a/model.h
+++ b/model.h
@@ -139,7 +139,7 @@ private:
         */
        void set_current_action(ModelAction *act) { priv->current_action = act; }
        Thread * check_current_action(ModelAction *curr);
-       ModelAction * initialize_curr_action(ModelAction *curr);
+       bool initialize_curr_action(ModelAction **curr);
        bool process_read(ModelAction *curr, bool second_part_of_rmw);
        bool process_write(ModelAction *curr);
        bool process_mutex(ModelAction *curr);