model: add process_relseq_fixup()

[model-checker.git] / model.cc

diff --git a/model.cc b/model.cc
index 2260431ab908973fe5b4233e9e15ceeb8be4ca2f..c5e41ab74c4be12cc8605860548abee71192a532 100644 (file)
--- a/model.cc
+++ b/model.cc
@@ -163,6 +163,10 @@ Thread * ModelChecker::get_next_thread(ModelAction *curr)
                        /* The next node will try to read from a different future value. */
                        tid = next->get_tid();
                        node_stack->pop_restofstack(2);
+               } else if (nextnode->increment_relseq_break()) {
+                       /* The next node will try to resolve a release sequence differently */
+                       tid = next->get_tid();
+                       node_stack->pop_restofstack(2);
                } else {
                        /* Make a different thread execute for next step */
                        Node *node = nextnode->get_parent();
@@ -540,6 +544,62 @@ bool ModelChecker::process_thread_action(ModelAction *curr)
        return updated;
 }
 
+/**
+ * @brief Process the current action for release sequence fixup activity
+ *
+ * Performs model-checker release sequence fixups for the current action,
+ * forcing a single pending release sequence to break (with a given, potential
+ * "loose" write) or to complete (i.e., synchronize). If a pending release
+ * sequence forms a complete release sequence, then we must perform the fixup
+ * synchronization, mo_graph additions, etc.
+ *
+ * @param curr The current action; must be a release sequence fixup action
+ * @param work_queue The work queue to which to add work items as they are
+ * generated
+ */
+void ModelChecker::process_relseq_fixup(ModelAction *curr, work_queue_t *work_queue)
+{
+       const ModelAction *write = curr->get_node()->get_relseq_break();
+       struct release_seq *sequence = pending_rel_seqs->back();
+       pending_rel_seqs->pop_back();
+       ASSERT(sequence);
+       ModelAction *acquire = sequence->acquire;
+       const ModelAction *rf = sequence->rf;
+       const ModelAction *release = sequence->release;
+       ASSERT(acquire);
+       ASSERT(release);
+       ASSERT(rf);
+       ASSERT(release->same_thread(rf));
+
+       if (write == NULL) {
+               /* Must synchronize */
+               if (!acquire->synchronize_with(release)) {
+                       set_bad_synchronization();
+                       return;
+               }
+               /* Re-check all pending release sequences */
+               work_queue->push_back(CheckRelSeqWorkEntry(NULL));
+               /* Re-check act for mo_graph edges */
+               work_queue->push_back(MOEdgeWorkEntry(acquire));
+
+               /* propagate synchronization to later actions */
+               action_list_t::reverse_iterator rit = action_trace->rbegin();
+               for (; (*rit) != acquire; rit++) {
+                       ModelAction *propagate = *rit;
+                       if (acquire->happens_before(propagate)) {
+                               propagate->synchronize_with(acquire);
+                               /* Re-check 'propagate' for mo_graph edges */
+                               work_queue->push_back(MOEdgeWorkEntry(propagate));
+                       }
+               }
+       } else {
+               /* Break release sequence with new edges:
+                *   release --mo--> write --mo--> rf */
+               mo_graph->addEdge(release, write);
+               mo_graph->addEdge(write, rf);
+       }
+}
+
 /**
  * Initialize the current action by performing one or more of the following
  * actions, as appropriate: merging RMWR and RMWC/RMW actions, stepping forward
@@ -591,6 +651,8 @@ ModelAction * ModelChecker::initialize_curr_action(ModelAction *curr)
                 */
                if (newcurr->is_write())
                        compute_promises(newcurr);
+               else if (newcurr->is_relseq_fixup())
+                       compute_relseq_breakwrites(newcurr);
        }
        return newcurr;
 }
@@ -678,6 +740,9 @@ Thread * ModelChecker::check_current_action(ModelAction *curr)
                        if (act->is_mutex_op() && process_mutex(act))
                                update_all = true;
 
+                       if (act->is_relseq_fixup())
+                               process_relseq_fixup(curr, &work_queue);
+
                        if (update_all)
                                work_queue.push_back(CheckRelSeqWorkEntry(NULL));
                        else if (update)
@@ -740,7 +805,8 @@ void ModelChecker::check_curr_backtracking(ModelAction * curr) {
        if ((!parnode->backtrack_empty() ||
                         !currnode->read_from_empty() ||
                         !currnode->future_value_empty() ||
-                        !currnode->promise_empty())
+                        !currnode->promise_empty() ||
+                        !currnode->relseq_break_empty())
                        && (!priv->next_backtrack ||
                                        *curr > *priv->next_backtrack)) {
                priv->next_backtrack = curr;
@@ -1258,8 +1324,10 @@ bool ModelChecker::release_seq_heads(const ModelAction *rf,
                bool future_ordered = false;
 
                ModelAction *last = get_last_action(int_to_id(i));
-               if (last && (rf->happens_before(last) ||
-                               get_thread(int_to_id(i))->is_complete()))
+               Thread *th = get_thread(int_to_id(i));
+               if ((last && rf->happens_before(last)) ||
+                               !scheduler->is_enabled(th) ||
+                               th->is_complete())
                        future_ordered = true;
 
                for (rit = list->rbegin(); rit != list->rend(); rit++) {
@@ -1650,6 +1718,29 @@ void ModelChecker::mo_check_promises(thread_id_t tid, const ModelAction *write)
        }
 }
 
+/**
+ * Compute the set of writes that may break the current pending release
+ * sequence. This information is extracted from previou release sequence
+ * calculations.
+ *
+ * @param curr The current ModelAction. Must be a release sequence fixup
+ * action.
+ */
+void ModelChecker::compute_relseq_breakwrites(ModelAction *curr)
+{
+       if (pending_rel_seqs->empty())
+               return;
+
+       struct release_seq *pending = pending_rel_seqs->back();
+       for (unsigned int i = 0; i < pending->writes.size(); i++) {
+               const ModelAction *write = pending->writes[i];
+               curr->get_node()->add_relseq_break(write);
+       }
+
+       /* NULL means don't break the sequence; just synchronize */
+       curr->get_node()->add_relseq_break(NULL);
+}
+
 /**
  * Build up an initial set of all past writes that this 'read' action may read
  * from. This set is determined by the clock vector's "happens before"