check in insane test case...

[model-checker.git] / model.cc

diff --git a/model.cc b/model.cc
index f0763cbfca28971b9dfd36a0fe5e76dcae41f8aa..7df70eebbe271c88486a4c85e4289217f1a40e4b 100644 (file)
--- a/model.cc
+++ b/model.cc
@@ -1051,25 +1051,66 @@ bool ModelChecker::process_mutex(ModelAction *curr)
        return false;
 }
 
+/**
+ * @brief Check if the current pending promises allow a future value to be sent
+ *
+ * If one of the following is true:
+ *  (a) there are no pending promises
+ *  (b) the reader and writer do not cross any promises
+ * Then, it is safe to pass a future value back now.
+ *
+ * Otherwise, we must save the pending future value until (a) or (b) is true
+ *
+ * @param writer The operation which sends the future value. Must be a write.
+ * @param reader The operation which will observe the value. Must be a read.
+ * @return True if the future value can be sent now; false if it must wait.
+ */
+bool ModelChecker::promises_may_allow(const ModelAction *writer,
+               const ModelAction *reader) const
+{
+       if (promises->empty())
+               return true;
+       for(int i=promises->size()-1;i>=0;i--) {
+               ModelAction *pr=(*promises)[i]->get_reader(0);
+               //reader is after promise...doesn't cross any promise
+               if (*reader > *pr)
+                       return true;
+               //writer is after promise, reader before...bad...
+               if (*writer > *pr)
+                       return false;
+       }
+       return true;
+}
+
+/**
+ * @brief Add a future value to a reader
+ *
+ * This function performs a few additional checks to ensure that the future
+ * value can be feasibly observed by the reader
+ *
+ * @param writer The operation whose value is sent. Must be a write.
+ * @param reader The read operation which may read the future value. Must be a read.
+ */
 void ModelChecker::add_future_value(const ModelAction *writer, ModelAction *reader)
 {
        /* Do more ambitious checks now that mo is more complete */
-       if (mo_may_allow(writer, reader)) {
-               Node *node = reader->get_node();
-
-               /* Find an ancestor thread which exists at the time of the reader */
-               Thread *write_thread = get_thread(writer);
-               while (id_to_int(write_thread->get_id()) >= node->get_num_threads())
-                       write_thread = write_thread->get_parent();
-
-               struct future_value fv = {
-                       writer->get_write_value(),
-                       writer->get_seq_number() + params.maxfuturedelay,
-                       write_thread->get_id(),
-               };
-               if (node->add_future_value(fv))
-                       set_latest_backtrack(reader);
-       }
+       if (!mo_may_allow(writer, reader))
+               return;
+
+       Node *node = reader->get_node();
+
+       /* Find an ancestor thread which exists at the time of the reader */
+       Thread *write_thread = get_thread(writer);
+       while (id_to_int(write_thread->get_id()) >= node->get_num_threads())
+               write_thread = write_thread->get_parent();
+
+       struct future_value fv = {
+               writer->get_write_value(),
+               writer->get_seq_number() + params.maxfuturedelay,
+               write_thread->get_id(),
+       };
+       if (node->add_future_value(fv))
+               set_latest_backtrack(reader);
 }
 
 /**
@@ -1094,19 +1135,27 @@ bool ModelChecker::process_write(ModelAction *curr)
        } else
                earliest_promise_reader = NULL;
 
-       /* Don't send future values to reads after the Promise we resolve */
        for (unsigned int i = 0; i < send_fv.size(); i++) {
                ModelAction *read = send_fv[i];
-               if (!earliest_promise_reader || *read < *earliest_promise_reader)
-                       futurevalues->push_back(PendingFutureValue(curr, read));
+
+               /* Don't send future values to reads after the Promise we resolve */
+               if (!earliest_promise_reader || *read < *earliest_promise_reader) {
+                       /* Check if future value can be sent immediately */
+                       if (promises_may_allow(curr, read)) {
+                               add_future_value(curr, read);
+                       } else {
+                               futurevalues->push_back(PendingFutureValue(curr, read));
+                       }
+               }
        }
 
-       if (promises->empty()) {
-               for (unsigned int i = 0; i < futurevalues->size(); i++) {
-                       struct PendingFutureValue pfv = (*futurevalues)[i];
+       /* Check the pending future values */
+       for (int i = (int)futurevalues->size() - 1; i >= 0; i--) {
+               struct PendingFutureValue pfv = (*futurevalues)[i];
+               if (promises_may_allow(pfv.writer, pfv.reader)) {
                        add_future_value(pfv.writer, pfv.reader);
+                       futurevalues->erase(futurevalues->begin() + i);
                }
-               futurevalues->clear();
        }
 
        mo_graph->commitChanges();
@@ -2049,7 +2098,7 @@ bool ModelChecker::w_modification_order(ModelAction *curr, ModelVector<ModelActi
 /** Arbitrary reads from the future are not allowed.  Section 29.3
  * part 9 places some constraints.  This method checks one result of constraint
  * constraint.  Others require compiler support. */
-bool ModelChecker::thin_air_constraint_may_allow(const ModelAction *writer, const ModelAction *reader)
+bool ModelChecker::thin_air_constraint_may_allow(const ModelAction *writer, const ModelAction *reader) const
 {
        if (!writer->is_rmw())
                return true;