return next;
}
+
/**
* Processes a read or rmw model action.
* @param curr is the read model action to process.
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();
curr->read_from(NULL);
- Promise *valuepromise = new Promise(curr, value);
+ Promise *valuepromise = new Promise(curr, value, expiration);
promises->push_back(valuepromise);
}
th->set_return_value(value);
second_part_of_rmw = true;
delete curr;
curr = tmp;
+ compute_promises(curr);
} else {
ModelAction *tmp = node_stack->explore_action(curr);
if (tmp) {
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() {
+ for (unsigned int promise_index = 0; promise_index < promises->size(); promise_index++) {
+ Promise *promise = (*promises)[promise_index];
+ if (promise->get_expiration()<priv->used_sequence_numbers) {
+ return true;
+ }
+ }
+ return false;
}
/** @returns whether the current partial trace must be a prefix of a
/** @returns whether the current partial trace is feasible. */
bool ModelChecker::isfeasible() {
- return !mo_graph->checkForCycles() && !failed_promise && !too_many_reads;
+ 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();
}
/** Returns whether the current completed trace is feasible. */
int tid = id_to_int(act->get_tid());
ModelAction *lastread = get_last_action(tid);
lastread->process_rmw(act);
- if (act->is_rmw())
+ if (act->is_rmw() && lastread->get_reads_from()!=NULL) {
mo_graph->addRMWEdge(lastread->get_reads_from(), lastread);
+ mo_graph->commitChanges();
+ }
return lastread;
}
action_list_t::reverse_iterator rit = list->rbegin();
/* Skip past curr */
- if (!already_added) {
+ if (already_added) {
for (; (*rit) != curr; rit++)
;
/* go past curr now */
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();
* The following edge should be handled elsewhere:
* readfrom(act) --mo--> act
*/
- if (act->is_write())
- mo_graph->addEdge(act, curr);
- else if (act->is_read() && act->get_reads_from() != NULL)
+ if (act->is_write()) {
+ //RMW shouldn't have an edge to themselves
+ if (act!=curr)
+ mo_graph->addEdge(act, curr);
+ } else if (act->is_read() && act->get_reads_from() != NULL)
mo_graph->addEdge(act->get_reads_from(), curr);
added = true;
break;
=>
that read could potentially read from our write.
*/
- if (act->get_node()->add_future_value(curr->get_value()) &&
- (!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())) {
+ if (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;
+ }
+ }
}
}
}
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)) {
ModelAction *read = promise->get_action();
read->read_from(write);
+ if (read->is_rmw()) {
+ mo_graph->addRMWEdge(write, read);
+ }
r_modification_order(read, write);
post_r_modification_order(read, write);
promises->erase(promises->begin() + promise_index);
} else
promise_index++;
}
-
return resolved;
}
+
+
/**
* Compute the set of promises that could potentially be satisfied by this
* action. Note that the set computation actually appears in the Node, not in
continue;
/* Don't consider more than one seq_cst write if we are a seq_cst read. */
- if (!act->is_seqcst() || !curr->is_seqcst() || act == last_seq_cst) {
+ if (!curr->is_seqcst()|| (!act->is_seqcst() && (last_seq_cst==NULL||!act->happens_before(last_seq_cst))) || act == last_seq_cst) {
DEBUG("Adding action to may_read_from:\n");
if (DBG_ENABLED()) {
act->print();
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())
projects / c11tester.git / blobdiff