2 #include "threads-model.h"
8 #include "concretepredicate.h"
13 #include "execution.h"
15 NewFuzzer::NewFuzzer() :
17 thrd_last_func_inst(),
18 thrd_selected_child_branch(),
21 paused_thread_table(128),
26 * @brief Register the ModelHistory and ModelExecution engine
28 void NewFuzzer::register_engine(ModelHistory * history, ModelExecution *execution)
30 this->history = history;
31 this->execution = execution;
34 int NewFuzzer::selectWrite(ModelAction *read, SnapVector<ModelAction *> * rf_set)
36 // return random() % rf_set->size();
38 thread_id_t tid = read->get_tid();
39 int thread_id = id_to_int(tid);
41 if (thrd_last_read_act.size() <= (uint) thread_id) {
42 thrd_last_read_act.resize(thread_id + 1);
43 thrd_last_func_inst.resize(thread_id + 1);
46 // A new read action is encountered, select a random child branch of current predicate
47 if (read != thrd_last_read_act[thread_id]) {
48 FuncNode * func_node = history->get_curr_func_node(tid);
49 Predicate * curr_pred = func_node->get_predicate_tree_position(tid);
51 FuncInst * read_inst = func_node->get_inst(read);
52 Predicate * selected_branch = selectBranch(tid, curr_pred, read_inst);
54 inst_act_map_t * inst_act_map = func_node->get_inst_act_map(tid);
55 prune_writes(tid, selected_branch, rf_set, inst_act_map);
57 if (!failed_predicates.isEmpty())
58 failed_predicates.reset();
60 thrd_last_read_act[thread_id] = read;
61 thrd_last_func_inst[thread_id] = read_inst;
64 // No write satisfies the selected predicate, so pause this thread.
65 while ( rf_set->size() == 0 ) {
66 Thread * read_thread = execution->get_thread(tid);
67 //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());
69 if (find_threads(read)) {
70 // reset thread pending action and revert sequence numbers
71 read_thread->set_pending(read);
72 read->reset_seq_number();
73 execution->restore_last_seq_num();
75 conditional_sleep(read_thread);
76 // Returning -1 stops the while loop of ModelExecution::process_read
79 Predicate * selected_branch = get_selected_child_branch(tid);
80 selected_branch->incr_fail_count();
81 failed_predicates.put(selected_branch, true);
83 SnapVector<ModelAction *> * pruned_writes = thrd_pruned_writes[thread_id];
84 for (uint i = 0; i < pruned_writes->size(); i++) {
85 rf_set->push_back( (*pruned_writes)[i] );
88 // Reselect a predicate and prune writes
89 Predicate * curr_pred = selected_branch->get_parent();
90 FuncInst * read_inst = thrd_last_func_inst[thread_id];
91 selected_branch = selectBranch(tid, curr_pred, read_inst);
93 FuncNode * func_node = history->get_curr_func_node(tid);
94 inst_act_map_t * inst_act_map = func_node->get_inst_act_map(tid);
95 prune_writes(tid, selected_branch, rf_set, inst_act_map);
97 ASSERT(selected_branch);
101 ASSERT(rf_set->size() != 0);
102 int random_index = random() % rf_set->size();
107 /* Select a random branch from the children of curr_pred
108 * @return The selected branch
110 Predicate * NewFuzzer::selectBranch(thread_id_t tid, Predicate * curr_pred, FuncInst * read_inst)
112 int thread_id = id_to_int(tid);
113 if ( thrd_selected_child_branch.size() <= (uint) thread_id)
114 thrd_selected_child_branch.resize(thread_id + 1);
116 if (curr_pred == NULL || read_inst == NULL) {
117 thrd_selected_child_branch[thread_id] = NULL;
121 ModelVector<Predicate *> * children = curr_pred->get_children();
122 SnapVector<Predicate *> branches;
123 uint32_t numerator = 1;
125 for (uint i = 0; i < children->size(); i++) {
126 Predicate * child = (*children)[i];
127 if (child->get_func_inst() == read_inst && !failed_predicates.contains(child)) {
128 branches.push_back(child);
130 // max of (exploration counts + 1)
131 if (child->get_expl_count() + 1 > numerator)
132 numerator = child->get_expl_count() + 1;
136 // predicate children have not been generated
137 if (branches.size() == 0) {
138 thrd_selected_child_branch[thread_id] = NULL;
142 // randomly select a branch
143 // int random_index = random() % branches.size();
144 // Predicate * random_branch = branches[ random_index ];
146 int index = choose_index(&branches, numerator);
147 Predicate * random_branch = branches[ index ];
148 thrd_selected_child_branch[thread_id] = random_branch;
150 // Update predicate tree position
151 FuncNode * func_node = history->get_curr_func_node(tid);
152 func_node->set_predicate_tree_position(tid, random_branch);
154 return random_branch;
158 * @brief Select a branch from the given predicate branches based
159 * on their exploration counts.
161 * Let b_1, ..., b_n be branches with exploration counts c_1, ..., c_n
162 * M := max(c_1, ..., c_n) + 1
163 * Factor f_i := M / (c_i + 1)
164 * The probability p_i that branch b_i is selected:
165 * p_i := f_i / (f_1 + ... + f_n)
166 * = \fraction{ 1/(c_i + 1) }{ 1/(c_1 + 1) + ... + 1/(c_n + 1) }
168 * Note: (1) c_i + 1 is used because counts may be 0.
169 * (2) The numerator of f_i is chosen to reduce the effect of underflow
171 * @param numerator is M defined above
173 int NewFuzzer::choose_index(SnapVector<Predicate *> * branches, uint32_t numerator)
175 if (branches->size() == 1)
178 double total_factor = 0;
179 SnapVector<double> factors = SnapVector<double>( branches->size() + 1 );
180 for (uint i = 0; i < branches->size(); i++) {
181 Predicate * branch = (*branches)[i];
182 double factor = (double) numerator / (branch->get_expl_count() + 5 * branch->get_fail_count() + 1);
183 total_factor += factor;
184 factors.push_back(factor);
187 double prob = (double) random() / RAND_MAX;
191 for (uint i = 0; i < factors.size(); i++) {
193 prob_sum += (double) (factors[i] / total_factor);
194 if (prob_sum > prob) {
202 Predicate * NewFuzzer::get_selected_child_branch(thread_id_t tid)
204 int thread_id = id_to_int(tid);
205 if (thrd_selected_child_branch.size() <= (uint) thread_id)
208 return thrd_selected_child_branch[thread_id];
211 /* Remove writes from the rf_set that do not satisfie the selected predicate,
212 * and store them in thrd_pruned_writes
214 * @return true if rf_set is pruned
216 bool NewFuzzer::prune_writes(thread_id_t tid, Predicate * pred,
217 SnapVector<ModelAction *> * rf_set, inst_act_map_t * inst_act_map)
222 PredExprSet * pred_expressions = pred->get_pred_expressions();
223 if (pred_expressions->getSize() == 0) // unset predicates
226 int thread_id = id_to_int(tid);
227 uint old_size = thrd_pruned_writes.size();
228 if (thrd_pruned_writes.size() <= (uint) thread_id) {
229 uint new_size = thread_id + 1;
230 thrd_pruned_writes.resize(new_size);
231 for (uint i = old_size; i < new_size; i++)
232 thrd_pruned_writes[i] = new SnapVector<ModelAction *>();
234 SnapVector<ModelAction *> * pruned_writes = thrd_pruned_writes[thread_id];
235 pruned_writes->clear(); // clear the old pruned_writes set
240 while ( index < rf_set->size() ) {
241 ModelAction * write_act = (*rf_set)[index];
242 uint64_t write_val = write_act->get_write_value();
243 bool satisfy_predicate = true;
245 PredExprSetIter * pred_expr_it = pred_expressions->iterator();
246 while (pred_expr_it->hasNext()) {
247 struct pred_expr * expression = pred_expr_it->next();
250 switch (expression->token) {
254 FuncInst * to_be_compared;
255 ModelAction * last_act;
258 to_be_compared = expression->func_inst;
259 last_act = inst_act_map->get(to_be_compared);
260 last_read = last_act->get_reads_from_value();
262 equality = (write_val == last_read);
263 if (equality != expression->value)
264 satisfy_predicate = false;
267 equality = ((void*)write_val == NULL);
268 if (equality != expression->value)
269 satisfy_predicate = false;
272 model_print("unknown predicate token\n");
276 if (!satisfy_predicate)
280 if (!satisfy_predicate) {
281 ASSERT(rf_set != NULL);
282 (*rf_set)[index] = rf_set->back();
284 pruned_writes->push_back(write_act);
293 /* @brief Put a thread to sleep because no writes in rf_set satisfies the selected predicate.
295 * @param thread A thread whose last action is a read
297 void NewFuzzer::conditional_sleep(Thread * thread)
299 int index = paused_thread_list.size();
301 model->getScheduler()->add_sleep(thread);
302 paused_thread_list.push_back(thread);
303 paused_thread_table.put(thread, index); // Update table
305 /* Add the waiting condition to ModelHistory */
306 ModelAction * read = thread->get_pending();
307 thread_id_t tid = thread->get_id();
308 FuncNode * func_node = history->get_curr_func_node(tid);
309 inst_act_map_t * inst_act_map = func_node->get_inst_act_map(tid);
311 Predicate * selected_branch = get_selected_child_branch(tid);
312 ConcretePredicate * concrete = selected_branch->evaluate(inst_act_map, tid);
313 concrete->set_location(read->get_location());
315 history->add_waiting_write(concrete);
316 /* history->add_waiting_thread is already called in find_threads */
319 bool NewFuzzer::has_paused_threads()
321 return paused_thread_list.size() != 0;
324 Thread * NewFuzzer::selectThread(int * threadlist, int numthreads)
326 if (numthreads == 0 && has_paused_threads()) {
327 wake_up_paused_threads(threadlist, &numthreads);
328 //model_print("list size: %d, active t id: %d\n", numthreads, threadlist[0]);
331 int random_index = random() % numthreads;
332 int thread = threadlist[random_index];
333 thread_id_t curr_tid = int_to_id(thread);
334 return execution->get_thread(curr_tid);
337 /* Force waking up one of threads paused by Fuzzer, because otherwise
338 * the Fuzzer is not making progress
340 void NewFuzzer::wake_up_paused_threads(int * threadlist, int * numthreads)
342 int random_index = random() % paused_thread_list.size();
343 Thread * thread = paused_thread_list[random_index];
344 model->getScheduler()->remove_sleep(thread);
346 Thread * last_thread = paused_thread_list.back();
347 paused_thread_list[random_index] = last_thread;
348 paused_thread_list.pop_back();
349 paused_thread_table.put(last_thread, random_index); // Update table
350 paused_thread_table.remove(thread);
352 thread_id_t tid = thread->get_id();
353 history->remove_waiting_write(tid);
354 history->remove_waiting_thread(tid);
356 threadlist[*numthreads] = tid;
359 Predicate * selected_branch = get_selected_child_branch(tid);
360 selected_branch->incr_fail_count();
361 model_print("thread %d is woken up\n", tid);
364 /* Wake up conditional sleeping threads if the desired write is available */
365 void NewFuzzer::notify_paused_thread(Thread * thread)
367 ASSERT(paused_thread_table.contains(thread));
369 int index = paused_thread_table.get(thread);
370 model->getScheduler()->remove_sleep(thread);
372 Thread * last_thread = paused_thread_list.back();
373 paused_thread_list[index] = last_thread;
374 paused_thread_list.pop_back();
375 paused_thread_table.put(last_thread, index); // Update table
376 paused_thread_table.remove(thread);
378 thread_id_t tid = thread->get_id();
379 history->remove_waiting_write(tid);
380 history->remove_waiting_thread(tid);
382 model_print("** thread %d is woken up\n", tid);
385 /* Find threads that may write values that the pending read action is waiting for
386 * @return True if any thread is found
388 bool NewFuzzer::find_threads(ModelAction * pending_read)
390 ASSERT(pending_read->is_read());
392 void * location = pending_read->get_location();
393 thread_id_t self_id = pending_read->get_tid();
394 bool finds_waiting_for = false;
396 SnapVector<FuncNode *> * func_node_list = history->getWrFuncNodes(location);
397 for (uint i = 0; i < func_node_list->size(); i++) {
398 FuncNode * target_node = (*func_node_list)[i];
399 for (uint i = 1; i < execution->get_num_threads(); i++) {
400 thread_id_t tid = int_to_id(i);
404 FuncNode * node = history->get_curr_func_node(tid);
405 /* It is possible that thread tid is not in any FuncNode */
409 int distance = node->compute_distance(target_node);
410 if (distance != -1) {
411 history->add_waiting_thread(self_id, tid, target_node, distance);
412 finds_waiting_for = true;
413 //model_print("thread: %d; distance from node %d to node %d: %d\n", tid, node->get_func_id(), target_node->get_func_id(), distance);
418 return finds_waiting_for;
421 bool NewFuzzer::shouldWait(const ModelAction * act)