action/model: backtrack for seq-cst and release/acquire fences

[model-checker.git] / action.cc

diff --git a/action.cc b/action.cc
index 9427c7d204e4a8e3a509f7cda437c7c67439e58f..3d46bd91aa0de6a2dd1a5729a1867fd3737343b3 100644 (file)
--- a/action.cc
+++ b/action.cc
@@ -37,7 +37,7 @@ ModelAction::ModelAction(action_type_t type, memory_order order, void *loc,
        sleep_flag(false)
 {
        /* References to NULL atomic variables can end up here */
-       ASSERT(loc || type == MODEL_FIXUP_RELSEQ);
+       ASSERT(loc || type == ATOMIC_FENCE || type == MODEL_FIXUP_RELSEQ);
 
        Thread *t = thread ? thread : thread_current();
        this->tid = t->get_id();
@@ -253,13 +253,15 @@ bool ModelAction::could_synchronize_with(const ModelAction *act) const
        if (!same_var(act))
                return false;
 
-       // Explore interleavings of seqcst writes to guarantee total order
-       // of seq_cst operations that don't commute
-       if ((could_be_write() || act->could_be_write()) && is_seqcst() && act->is_seqcst())
+       // Explore interleavings of seqcst writes/fences to guarantee total
+       // order of seq_cst operations that don't commute
+       if ((could_be_write() || act->could_be_write() || is_fence() || act->is_fence())
+                       && is_seqcst() && act->is_seqcst())
                return true;
 
-       // Explore synchronizing read/write pairs
-       if (is_read() && is_acquire() && act->could_be_write() && act->is_release())
+       // Explore synchronizing read/write/fence pairs
+       if (is_acquire() && act->is_release() && (is_read() || is_fence()) &&
+                       (act->could_be_write() || act->is_fence()))
                return true;
 
        //lock just released...we can grab lock