NewFuzzer::NewFuzzer() :
thrd_last_read_act(),
- thrd_curr_pred(),
+ thrd_last_func_inst(),
thrd_selected_child_branch(),
thrd_pruned_writes(),
paused_thread_list(),
- paused_thread_table(128)
+ paused_thread_table(128),
+ failed_predicates(32)
{}
/**
thread_id_t tid = read->get_tid();
int thread_id = id_to_int(tid);
- if (thrd_last_read_act.size() <= (uint) thread_id)
+ if (thrd_last_read_act.size() <= (uint) thread_id) {
thrd_last_read_act.resize(thread_id + 1);
+ thrd_last_func_inst.resize(thread_id + 1);
+ }
// A new read action is encountered, select a random child branch of current predicate
if (read != thrd_last_read_act[thread_id]) {
- thrd_last_read_act[thread_id] = read;
-
FuncNode * func_node = history->get_curr_func_node(tid);
Predicate * curr_pred = func_node->get_predicate_tree_position(tid);
+
FuncInst * read_inst = func_node->get_inst(read);
Predicate * selected_branch = selectBranch(tid, curr_pred, read_inst);
inst_act_map_t * inst_act_map = func_node->get_inst_act_map(tid);
prune_writes(tid, selected_branch, rf_set, inst_act_map);
+
+ if (!failed_predicates.isEmpty())
+ failed_predicates.reset();
+
+ thrd_last_read_act[thread_id] = read;
+ thrd_last_func_inst[thread_id] = read_inst;
}
// No write satisfies the selected predicate, so pause this thread.
- if ( rf_set->size() == 0 ) {
+ while ( rf_set->size() == 0 ) {
Thread * read_thread = execution->get_thread(tid);
- model_print("the %d read action of thread %d at %p is unsuccessful\n", read->get_seq_number(), read_thread->get_id(), read->get_location());
-
- // reset thread pending action and revert sequence numbers
- read_thread->set_pending(read);
- read->reset_seq_number();
- execution->restore_last_seq_num();
-
- conditional_sleep(read_thread);
-
- return -1;
-/*
- SnapVector<ModelAction *> * pruned_writes = thrd_pruned_writes[thread_id];
- for (uint i = 0; i < pruned_writes->size(); i++)
- rf_set->push_back( (*pruned_writes)[i] );
- pruned_writes->clear();
-*/
+ Predicate * selected_branch = get_selected_child_branch(tid);
+ bool should_reselect_predicate = false;
+ //model_print("the %d read action of thread %d at %p is unsuccessful\n", read->get_seq_number(), read_thread->get_id(), read->get_location());
+
+ if (!find_threads(read)) {
+ update_predicate_score(selected_branch, SLEEP_FAIL_TYPE1);
+ should_reselect_predicate = true;
+ } else if (!should_conditional_sleep(selected_branch)) {
+ update_predicate_score(selected_branch, SLEEP_FAIL_TYPE2);
+ should_reselect_predicate = true;
+ } else {
+ // reset thread pending action and revert sequence numbers
+ read_thread->set_pending(read);
+ read->reset_seq_number();
+ execution->restore_last_seq_num();
+
+ conditional_sleep(read_thread);
+ // Returning -1 stops the while loop of ModelExecution::process_read
+ return -1;
+ }
+
+ if (should_reselect_predicate) {
+ SnapVector<ModelAction *> * pruned_writes = thrd_pruned_writes[thread_id];
+ for (uint i = 0; i < pruned_writes->size(); i++) {
+ rf_set->push_back( (*pruned_writes)[i] );
+ }
+
+ // Reselect a predicate and prune writes
+ Predicate * curr_pred = selected_branch->get_parent();
+ FuncInst * read_inst = thrd_last_func_inst[thread_id];
+ selected_branch = selectBranch(tid, curr_pred, read_inst);
+
+ FuncNode * func_node = history->get_curr_func_node(tid);
+ inst_act_map_t * inst_act_map = func_node->get_inst_act_map(tid);
+ prune_writes(tid, selected_branch, rf_set, inst_act_map);
+
+ ASSERT(selected_branch);
+ }
}
ASSERT(rf_set->size() != 0);
ModelVector<Predicate *> * children = curr_pred->get_children();
SnapVector<Predicate *> branches;
+ uint32_t numerator = 1;
for (uint i = 0; i < children->size(); i++) {
Predicate * child = (*children)[i];
- if (child->get_func_inst() == read_inst)
+ if (child->get_func_inst() == read_inst && !failed_predicates.contains(child)) {
branches.push_back(child);
+
+ // max of (exploration counts + 1)
+ if (child->get_expl_count() + 1 > numerator)
+ numerator = child->get_expl_count() + 1;
+ }
}
// predicate children have not been generated
}
// randomly select a branch
- int random_index = random() % branches.size();
- Predicate * random_branch = branches[ random_index ];
+ // int random_index = random() % branches.size();
+ // Predicate * random_branch = branches[ random_index ];
+
+ int index = choose_index(&branches, numerator);
+ Predicate * random_branch = branches[ index ];
thrd_selected_child_branch[thread_id] = random_branch;
+ // Update predicate tree position
+ FuncNode * func_node = history->get_curr_func_node(tid);
+ func_node->set_predicate_tree_position(tid, random_branch);
+
return random_branch;
}
+/**
+ * @brief Select a branch from the given predicate branches based
+ * on their exploration counts.
+ *
+ * Let b_1, ..., b_n be branches with exploration counts c_1, ..., c_n
+ * M := max(c_1, ..., c_n) + 1
+ * Factor f_i := M / (c_i + 1)
+ * The probability p_i that branch b_i is selected:
+ * p_i := f_i / (f_1 + ... + f_n)
+ * = \fraction{ 1/(c_i + 1) }{ 1/(c_1 + 1) + ... + 1/(c_n + 1) }
+ *
+ * Note: (1) c_i + 1 is used because counts may be 0.
+ * (2) The numerator of f_i is chosen to reduce the effect of underflow
+ *
+ * @param numerator is M defined above
+ */
+int NewFuzzer::choose_index(SnapVector<Predicate *> * branches, uint32_t numerator)
+{
+ if (branches->size() == 1)
+ return 0;
+
+ double total_factor = 0;
+ SnapVector<double> factors = SnapVector<double>( branches->size() + 1 );
+ for (uint i = 0; i < branches->size(); i++) {
+ Predicate * branch = (*branches)[i];
+ double factor = (double) numerator / (branch->get_expl_count() + 5 * branch->get_fail_count() + 1);
+ total_factor += factor;
+ factors.push_back(factor);
+ }
+
+ double prob = (double) random() / RAND_MAX;
+ double prob_sum = 0;
+ int index = 0;
+
+ for (uint i = 0; i < factors.size(); i++) {
+ index = i;
+ prob_sum += (double) (factors[i] / total_factor);
+ if (prob_sum > prob) {
+ break;
+ }
+ }
+
+ return index;
+}
+
Predicate * NewFuzzer::get_selected_child_branch(thread_id_t tid)
{
int thread_id = id_to_int(tid);
bool pruned = false;
uint index = 0;
- ConcretePredicate * concrete_pred = pred->evaluate(inst_act_map, tid);
- SnapVector<struct concrete_pred_expr> * concrete_exprs = concrete_pred->getExpressions();
-
while ( index < rf_set->size() ) {
ModelAction * write_act = (*rf_set)[index];
uint64_t write_val = write_act->get_write_value();
bool satisfy_predicate = true;
- for (uint i = 0; i < concrete_exprs->size(); i++) {
- struct concrete_pred_expr concrete = (*concrete_exprs)[i];
+ PredExprSetIter * pred_expr_it = pred_expressions->iterator();
+ while (pred_expr_it->hasNext()) {
+ struct pred_expr * expression = pred_expr_it->next();
bool equality;
- switch (concrete.token) {
+ switch (expression->token) {
case NOPREDICATE:
return false;
case EQUALITY:
- equality = (write_val == concrete.value);
- if (equality != concrete.equality)
+ FuncInst * to_be_compared;
+ ModelAction * last_act;
+ uint64_t last_read;
+
+ to_be_compared = expression->func_inst;
+ last_act = inst_act_map->get(to_be_compared);
+ last_read = last_act->get_reads_from_value();
+
+ equality = (write_val == last_read);
+ if (equality != expression->value)
satisfy_predicate = false;
break;
case NULLITY:
equality = ((void*)write_val == NULL);
- if (equality != concrete.equality)
+ if (equality != expression->value)
satisfy_predicate = false;
break;
default:
index++;
}
- delete concrete_pred;
-
return pruned;
}
concrete->set_location(read->get_location());
history->add_waiting_write(concrete);
+ /* history->add_waiting_thread is already called in find_threads */
+}
- /* history->add_waiting_thread is called in find_threads */
- find_threads(read);
+bool NewFuzzer::should_conditional_sleep(Predicate *)
+{
+ return true;
}
bool NewFuzzer::has_paused_threads()
int random_index = random() % numthreads;
int thread = threadlist[random_index];
thread_id_t curr_tid = int_to_id(thread);
- return model->get_thread(curr_tid);
+ return execution->get_thread(curr_tid);
}
/* Force waking up one of threads paused by Fuzzer, because otherwise
history->remove_waiting_write(tid);
history->remove_waiting_thread(tid);
- model_print("thread %d is woken up\n", tid);
threadlist[*numthreads] = tid;
(*numthreads)++;
+
+ Predicate * selected_branch = get_selected_child_branch(tid);
+ update_predicate_score(selected_branch, SLEEP_FAIL_TYPE3);
+
+ model_print("thread %d is woken up\n", tid);
}
/* Wake up conditional sleeping threads if the desired write is available */
thread_id_t tid = thread->get_id();
history->remove_waiting_write(tid);
history->remove_waiting_thread(tid);
+
+ Predicate * selected_branch = get_selected_child_branch(tid);
+ update_predicate_score(selected_branch, SLEEP_SUCCESS);
+
+ model_print("** thread %d is woken up\n", tid);
}
-/* Find threads that may write values that the pending read action is waiting for */
-void NewFuzzer::find_threads(ModelAction * pending_read)
+/* Find threads that may write values that the pending read action is waiting for
+ * @return True if any thread is found
+ */
+bool NewFuzzer::find_threads(ModelAction * pending_read)
{
ASSERT(pending_read->is_read());
void * location = pending_read->get_location();
thread_id_t self_id = pending_read->get_tid();
+ bool finds_waiting_for = false;
SnapVector<FuncNode *> * func_node_list = history->getWrFuncNodes(location);
for (uint i = 0; i < func_node_list->size(); i++) {
int distance = node->compute_distance(target_node);
if (distance != -1) {
history->add_waiting_thread(self_id, tid, target_node, distance);
- model_print("thread: %d; distance from node %d to node %d: %d\n", tid, node->get_func_id(), target_node->get_func_id(), distance);
-
+ finds_waiting_for = true;
+ //model_print("thread: %d; distance from node %d to node %d: %d\n", tid, node->get_func_id(), target_node->get_func_id(), distance);
}
-
}
}
+
+ return finds_waiting_for;
+}
+
+/* Update predicate counts and scores (asynchronous) when the read value is not available
+ *
+ * @param type
+ * type 1: find_threads return false
+ * type 2: find_threads return true, but the fuzzer decides that that thread shall not sleep based on sleep score
+ * type 3: threads are put to sleep but woken up before the waited value appears
+ * type 4: threads are put to sleep and the waited vaule appears (success)
+ */
+void NewFuzzer::update_predicate_score(Predicate * predicate, sleep_result_t type)
+{
+ switch (type) {
+ case SLEEP_FAIL_TYPE1:
+ predicate->incr_fail_count();
+
+ /* Do not choose this predicate when reselecting a new branch */
+ failed_predicates.put(predicate, true);
+ break;
+ case SLEEP_FAIL_TYPE2:
+ predicate->incr_fail_count();
+ predicate->decr_sleep_score(1);
+ failed_predicates.put(predicate, true);
+ break;
+ case SLEEP_FAIL_TYPE3:
+ predicate->incr_fail_count();
+ predicate->incr_sleep_score(10);
+ break;
+ case SLEEP_SUCCESS:
+ predicate->decr_sleep_score(10);
+ break;
+ default:
+ model_print("unknown predicate result type.\n");
+ break;
+ }
}
bool NewFuzzer::shouldWait(const ModelAction * act)
projects / c11tester.git / blobdiff