obj_map(new HashTable<const void *, action_list_t, uintptr_t, 4>()),
obj_thrd_map(new HashTable<void *, std::vector<action_list_t>, uintptr_t, 4 >()),
promises(new std::vector<Promise *>()),
+ futurevalues(new std::vector<struct PendingFutureValue>()),
lazy_sync_with_release(new HashTable<void *, std::list<ModelAction *>, uintptr_t, 4>()),
thrd_last_action(new std::vector<ModelAction *>(1)),
node_stack(new NodeStack()),
* @param second_part_of_rmw is boolean that is true is this is the second action of a rmw.
* @return True if processing this read updates the mo_graph.
*/
-
bool ModelChecker::process_read(ModelAction *curr, Thread * th, bool second_part_of_rmw) {
uint64_t value;
bool updated=false;
while(true) {
const ModelAction *reads_from = curr->get_node()->get_read_from();
if (reads_from != NULL) {
+ mo_graph->startChanges();
+
value = reads_from->get_value();
- /* Assign reads_from, perform release/acquire synchronization */
- curr->read_from(reads_from);
+
if (!second_part_of_rmw) {
check_recency(curr,false);
}
continue;
}
+ curr->read_from(reads_from);
mo_graph->commitChanges();
updated |= r_status;
- } else {
+ } else if (!second_part_of_rmw) {
/* Read from future value */
value = curr->get_node()->get_future_value();
modelclock_t expiration = curr->get_node()->get_future_value_expiration();
bool updated_promises=resolve_promises(curr);
updated=updated_mod_order|updated_promises;
+ if (promises->size()==0) {
+ for(unsigned int i=0;i<futurevalues->size();i++) {
+ struct PendingFutureValue pfv=(*futurevalues)[i];
+ if (pfv.act->get_node()->add_future_value(pfv.value, pfv.expiration) &&
+ (!priv->next_backtrack || *pfv.act > *priv->next_backtrack))
+ priv->next_backtrack = pfv.act;
+ }
+ futurevalues->resize(0);
+ }
+
mo_graph->commitChanges();
th->set_return_value(VALUE_NONE);
}
if (!second_part_of_rmw)
add_action_to_lists(curr);
+ check_curr_backtracking(curr);
+
+ set_backtracking(curr);
+
+ return get_next_thread(curr);
+}
+
+void ModelChecker::check_curr_backtracking(ModelAction * curr) {
Node *currnode = curr->get_node();
Node *parnode = currnode->get_parent();
if ((!parnode->backtrack_empty() ||
- !currnode->read_from_empty() ||
- !currnode->future_value_empty() ||
- !currnode->promise_empty())
- && (!priv->next_backtrack ||
- *curr > *priv->next_backtrack)) {
+ !currnode->read_from_empty() ||
+ !currnode->future_value_empty() ||
+ !currnode->promise_empty())
+ && (!priv->next_backtrack ||
+ *curr > *priv->next_backtrack)) {
priv->next_backtrack = curr;
}
-
- set_backtracking(curr);
-
- return get_next_thread(curr);
}
bool ModelChecker::promises_expired() {
/** @returns whether the current partial trace is feasible. */
bool ModelChecker::isfeasible() {
+ return !mo_graph->checkForRMWViolation() && isfeasibleotherthanRMW();
+}
+
+/** @returns whether the current partial trace is feasible other than
+ * multiple RMW reading from the same store. */
+bool ModelChecker::isfeasibleotherthanRMW() {
return !mo_graph->checkForCycles() && !failed_promise && !too_many_reads && !promises_expired();
}
continue;
/* Test to see whether this is a feasible write to read from*/
+ mo_graph->startChanges();
r_modification_order(curr, write);
bool feasiblereadfrom=isfeasible();
mo_graph->rollbackChanges();
=>
that read could potentially read from our write.
*/
- if (isfeasible() && act->get_node()->add_future_value(curr->get_value(), curr->get_seq_number()+params.maxfuturedelay) &&
- (!priv->next_backtrack || *act > *priv->next_backtrack))
- priv->next_backtrack = act;
+ if (thin_air_constraint_may_allow(curr, act)) {
+ if (isfeasible() ||
+ (curr->is_rmw() && act->is_rmw() && curr->get_reads_from()==act->get_reads_from() && isfeasibleotherthanRMW())) {
+ struct PendingFutureValue pfv={curr->get_value(),curr->get_seq_number()+params.maxfuturedelay,act};
+ futurevalues->push_back(pfv);
+ }
+ }
}
}
}
return added;
}
+/** 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) {
+ if (!writer->is_rmw())
+ return true;
+
+ if (!reader->is_rmw())
+ return true;
+
+ for(const ModelAction *search=writer->get_reads_from();search!=NULL;search=search->get_reads_from()) {
+ if (search==reader)
+ return false;
+ if (search->get_tid()==reader->get_tid()&&
+ search->happens_before(reader))
+ break;
+ }
+
+ return true;
+}
+
/**
* Finds the head(s) of the release sequence(s) containing a given ModelAction.
* The ModelAction under consideration is expected to be taking part in
bool ModelChecker::resolve_promises(ModelAction *write)
{
bool resolved = false;
+
for (unsigned int i = 0, promise_index = 0; promise_index < promises->size(); i++) {
Promise *promise = (*promises)[promise_index];
if (write->get_node()->get_promise(i)) {
} else
promise_index++;
}
-
return resolved;
}
if (curr) {
if (curr->get_state() == THREAD_READY) {
ASSERT(priv->current_action);
+
priv->nextThread = check_current_action(priv->current_action);
priv->current_action = NULL;
if (!curr->is_blocked() && !curr->is_complete())