2 #include "threads-model.h"
7 #include "concretepredicate.h"
12 #include "execution.h"
14 NewFuzzer::NewFuzzer() :
16 thrd_last_func_inst(),
17 thrd_selected_child_branch(),
20 paused_thread_table(128),
21 failed_predicates(32),
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);
50 FuncInst * read_inst = func_node->get_inst(read);
51 inst_act_map_t * inst_act_map = func_node->get_inst_act_map(tid);
53 check_store_visibility(curr_pred, read_inst, inst_act_map, rf_set);
54 Predicate * selected_branch = selectBranch(tid, curr_pred, read_inst);
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 Predicate * selected_branch = get_selected_child_branch(tid);
68 //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());
71 Thread * read_thread = execution->get_thread(tid);
72 bool should_reselect_predicate = true;
73 bool should_sleep = should_conditional_sleep(selected_branch);
74 dist_info_vec.clear();
76 if (!find_threads(read)) {
77 update_predicate_score(selected_branch, SLEEP_FAIL_TYPE1);
78 should_reselect_predicate = true;
79 } else if (!should_sleep) {
80 update_predicate_score(selected_branch, SLEEP_FAIL_TYPE2);
81 should_reselect_predicate = true;
83 for (uint i = 0; i < dist_info_vec.size(); i++) {
84 struct node_dist_info info = dist_info_vec[i];
85 history->add_waiting_thread(tid, info.tid, info.target, info.dist);
88 // reset thread pending action and revert sequence numbers
89 read_thread->set_pending(read);
90 read->reset_seq_number();
91 execution->restore_last_seq_num();
93 conditional_sleep(read_thread);
94 // Returning -1 stops the while loop of ModelExecution::process_read
99 SnapVector<ModelAction *> * pruned_writes = thrd_pruned_writes[thread_id];
100 for (uint i = 0; i < pruned_writes->size(); i++) {
101 rf_set->push_back( (*pruned_writes)[i] );
104 // Reselect a predicate and prune writes
105 Predicate * curr_pred = selected_branch->get_parent();
106 FuncInst * read_inst = thrd_last_func_inst[thread_id];
107 selected_branch = selectBranch(tid, curr_pred, read_inst);
109 FuncNode * func_node = history->get_curr_func_node(tid);
110 inst_act_map_t * inst_act_map = func_node->get_inst_act_map(tid);
111 prune_writes(tid, selected_branch, rf_set, inst_act_map);
113 ASSERT(selected_branch);
116 ASSERT(rf_set->size() != 0);
117 int random_index = random() % rf_set->size();
122 void NewFuzzer::check_store_visibility(Predicate * curr_pred, FuncInst * read_inst,
123 inst_act_map_t * inst_act_map, SnapVector<ModelAction *> * rf_set)
125 ASSERT(!rf_set->empty());
126 if (curr_pred == NULL || read_inst == NULL)
129 ModelVector<Predicate *> * children = curr_pred->get_children();
130 SnapVector<Predicate *> branches;
132 /* The children predicates may have different FuncInsts */
133 for (uint i = 0; i < children->size(); i++) {
134 Predicate * child = (*children)[i];
135 if (child->get_func_inst() == read_inst) {
136 branches.push_back(child);
140 /* Predicate children have not been generated */
141 if (branches.empty())
144 /* Iterate over all predicate children */
145 for (uint i = 0; i < branches.size(); i++) {
146 Predicate * branch = branches[i];
147 PredExprSet * pred_expressions = branch->get_pred_expressions();
149 /* Do not check unset predicates */
150 if (pred_expressions->isEmpty())
153 branch->incr_total_checking_count();
155 /* Iterate over all write actions */
156 for (uint j = 0; j < rf_set->size(); j++) {
157 ModelAction * write_act = (*rf_set)[j];
158 uint64_t write_val = write_act->get_write_value();
160 bool satisfy_predicate = check_predicate_expressions(pred_expressions, inst_act_map, write_val, &dummy);
162 /* If one write value satisfies the predicate, go to check the next predicate */
163 if (satisfy_predicate) {
164 branch->incr_store_visible_count();
172 /* Select a random branch from the children of curr_pred
173 * @return The selected branch
175 Predicate * NewFuzzer::selectBranch(thread_id_t tid, Predicate * curr_pred, FuncInst * read_inst)
177 int thread_id = id_to_int(tid);
178 if ( thrd_selected_child_branch.size() <= (uint) thread_id)
179 thrd_selected_child_branch.resize(thread_id + 1);
181 if (curr_pred == NULL || read_inst == NULL) {
182 thrd_selected_child_branch[thread_id] = NULL;
186 ModelVector<Predicate *> * children = curr_pred->get_children();
187 SnapVector<Predicate *> branches;
189 for (uint i = 0; i < children->size(); i++) {
190 Predicate * child = (*children)[i];
191 if (child->get_func_inst() == read_inst && !failed_predicates.contains(child)) {
192 branches.push_back(child);
194 /*-- max of (exploration counts + 1)
195 if (child->get_expl_count() + 1 > numerator)
196 numerator = child->get_expl_count() + 1;
201 // predicate children have not been generated
202 if (branches.size() == 0) {
203 thrd_selected_child_branch[thread_id] = NULL;
207 int index = choose_index(&branches, 0);
208 Predicate * random_branch = branches[ index ];
209 thrd_selected_child_branch[thread_id] = random_branch;
211 // Update predicate tree position
212 FuncNode * func_node = history->get_curr_func_node(tid);
213 func_node->set_predicate_tree_position(tid, random_branch);
215 return random_branch;
219 * @brief Select a branch from the given predicate branches based
220 * on their exploration counts.
222 * Let b_1, ..., b_n be branches with exploration counts c_1, ..., c_n
223 * M := max(c_1, ..., c_n) + 1
224 * Factor f_i := M / (c_i + 1)
225 * The probability p_i that branch b_i is selected:
226 * p_i := f_i / (f_1 + ... + f_n)
227 * = \fraction{ 1/(c_i + 1) }{ 1/(c_1 + 1) + ... + 1/(c_n + 1) }
229 * Note: (1) c_i + 1 is used because counts may be 0.
230 * (2) The numerator of f_i is chosen to reduce the effect of underflow
232 * @param numerator is M defined above
234 int NewFuzzer::choose_index(SnapVector<Predicate *> * branches, uint32_t numerator)
236 return random() % branches->size();
238 if (branches->size() == 1)
241 double total_factor = 0;
242 SnapVector<double> factors = SnapVector<double>( branches->size() + 1 );
243 for (uint i = 0; i < branches->size(); i++) {
244 Predicate * branch = (*branches)[i];
245 double factor = (double) numerator / (branch->get_expl_count() + 5 * branch->get_fail_count() + 1);
246 total_factor += factor;
247 factors.push_back(factor);
250 double prob = (double) random() / RAND_MAX;
254 for (uint i = 0; i < factors.size(); i++) {
256 prob_sum += (double) (factors[i] / total_factor);
257 if (prob_sum > prob) {
266 Predicate * NewFuzzer::get_selected_child_branch(thread_id_t tid)
268 int thread_id = id_to_int(tid);
269 if (thrd_selected_child_branch.size() <= (uint) thread_id)
272 return thrd_selected_child_branch[thread_id];
275 /* Remove writes from the rf_set that do not satisfie the selected predicate,
276 * and store them in thrd_pruned_writes
278 * @return true if rf_set is pruned
280 bool NewFuzzer::prune_writes(thread_id_t tid, Predicate * pred,
281 SnapVector<ModelAction *> * rf_set, inst_act_map_t * inst_act_map)
286 PredExprSet * pred_expressions = pred->get_pred_expressions();
287 if (pred_expressions->getSize() == 0) // unset predicates
290 int thread_id = id_to_int(tid);
291 uint old_size = thrd_pruned_writes.size();
292 if (thrd_pruned_writes.size() <= (uint) thread_id) {
293 uint new_size = thread_id + 1;
294 thrd_pruned_writes.resize(new_size);
295 for (uint i = old_size; i < new_size; i++)
296 thrd_pruned_writes[i] = new SnapVector<ModelAction *>();
298 SnapVector<ModelAction *> * pruned_writes = thrd_pruned_writes[thread_id];
299 pruned_writes->clear(); // clear the old pruned_writes set
304 while ( index < rf_set->size() ) {
305 ModelAction * write_act = (*rf_set)[index];
306 uint64_t write_val = write_act->get_write_value();
307 bool no_predicate = false;
308 bool satisfy_predicate = check_predicate_expressions(pred_expressions, inst_act_map, write_val, &no_predicate);
313 if (!satisfy_predicate) {
314 ASSERT(rf_set != NULL);
315 (*rf_set)[index] = rf_set->back();
317 pruned_writes->push_back(write_act);
326 /* @brief Put a thread to sleep because no writes in rf_set satisfies the selected predicate.
328 * @param thread A thread whose last action is a read
330 void NewFuzzer::conditional_sleep(Thread * thread)
332 int index = paused_thread_list.size();
334 model->getScheduler()->add_sleep(thread);
335 paused_thread_list.push_back(thread);
336 paused_thread_table.put(thread, index); // Update table
338 /* Add the waiting condition to ModelHistory */
339 ModelAction * read = thread->get_pending();
340 thread_id_t tid = thread->get_id();
341 FuncNode * func_node = history->get_curr_func_node(tid);
342 inst_act_map_t * inst_act_map = func_node->get_inst_act_map(tid);
344 Predicate * selected_branch = get_selected_child_branch(tid);
345 ConcretePredicate * concrete = selected_branch->evaluate(inst_act_map, tid);
346 concrete->set_location(read->get_location());
348 history->add_waiting_write(concrete);
349 /* history->add_waiting_thread is already called in find_threads */
353 * Decides whether a thread should condition sleep based on
354 * the sleep score of the chosen predicate.
356 * sleep_score = 0: never sleeps
357 * sleep_score = 100: always sleeps
359 bool NewFuzzer::should_conditional_sleep(Predicate * predicate)
363 int sleep_score = predicate->get_sleep_score();
364 int random_num = random() % 100;
366 // should sleep if random_num falls within [0, sleep_score)
367 if (random_num < sleep_score)
374 bool NewFuzzer::has_paused_threads()
376 return paused_thread_list.size() != 0;
379 Thread * NewFuzzer::selectThread(int * threadlist, int numthreads)
381 if (numthreads == 0 && has_paused_threads()) {
382 wake_up_paused_threads(threadlist, &numthreads);
383 //model_print("list size: %d, active t id: %d\n", numthreads, threadlist[0]);
386 int random_index = random() % numthreads;
387 int thread = threadlist[random_index];
388 thread_id_t curr_tid = int_to_id(thread);
389 return execution->get_thread(curr_tid);
392 /* Force waking up one of threads paused by Fuzzer, because otherwise
393 * the Fuzzer is not making progress
395 void NewFuzzer::wake_up_paused_threads(int * threadlist, int * numthreads)
397 int random_index = random() % paused_thread_list.size();
398 Thread * thread = paused_thread_list[random_index];
399 model->getScheduler()->remove_sleep(thread);
401 Thread * last_thread = paused_thread_list.back();
402 paused_thread_list[random_index] = last_thread;
403 paused_thread_list.pop_back();
404 paused_thread_table.put(last_thread, random_index); // Update table
405 paused_thread_table.remove(thread);
407 thread_id_t tid = thread->get_id();
408 history->remove_waiting_write(tid);
409 history->remove_waiting_thread(tid);
411 threadlist[*numthreads] = tid;
415 Predicate * selected_branch = get_selected_child_branch(tid);
416 update_predicate_score(selected_branch, SLEEP_FAIL_TYPE3);
419 model_print("thread %d is woken up\n", tid);
422 /* Wake up conditional sleeping threads if the desired write is available */
423 void NewFuzzer::notify_paused_thread(Thread * thread)
425 ASSERT(paused_thread_table.contains(thread));
427 int index = paused_thread_table.get(thread);
428 model->getScheduler()->remove_sleep(thread);
430 Thread * last_thread = paused_thread_list.back();
431 paused_thread_list[index] = last_thread;
432 paused_thread_list.pop_back();
433 paused_thread_table.put(last_thread, index); // Update table
434 paused_thread_table.remove(thread);
436 thread_id_t tid = thread->get_id();
437 history->remove_waiting_write(tid);
438 history->remove_waiting_thread(tid);
441 Predicate * selected_branch = get_selected_child_branch(tid);
442 update_predicate_score(selected_branch, SLEEP_SUCCESS);
445 model_print("** thread %d is woken up\n", tid);
448 /* Find threads that may write values that the pending read action is waiting for.
449 * Side effect: waiting thread related info are stored in dist_info_vec
451 * @return True if any thread is found
453 bool NewFuzzer::find_threads(ModelAction * pending_read)
455 ASSERT(pending_read->is_read());
457 void * location = pending_read->get_location();
458 thread_id_t self_id = pending_read->get_tid();
459 bool finds_waiting_for = false;
461 SnapVector<FuncNode *> * func_node_list = history->getWrFuncNodes(location);
462 for (uint i = 0; i < func_node_list->size(); i++) {
463 FuncNode * target_node = (*func_node_list)[i];
464 for (uint i = 1; i < execution->get_num_threads(); i++) {
465 thread_id_t tid = int_to_id(i);
469 FuncNode * node = history->get_curr_func_node(tid);
470 /* It is possible that thread tid is not in any FuncNode */
474 int distance = node->compute_distance(target_node);
475 if (distance != -1) {
476 finds_waiting_for = true;
477 //model_print("thread: %d; distance from node %d to node %d: %d\n", tid, node->get_func_id(), target_node->get_func_id(), distance);
479 dist_info_vec.push_back(node_dist_info(tid, target_node, distance));
484 return finds_waiting_for;
487 /* Update predicate counts and scores (asynchronous) when the read value is not available
490 * type 1: find_threads return false
491 * type 2: find_threads return true, but the fuzzer decides that that thread shall not sleep based on sleep score
492 * type 3: threads are put to sleep but woken up before the waited value appears
493 * type 4: threads are put to sleep and the waited vaule appears (success)
497 void NewFuzzer::update_predicate_score(Predicate * predicate, sleep_result_t type)
500 case SLEEP_FAIL_TYPE1:
501 predicate->incr_fail_count();
503 // Do not choose this predicate when reselecting a new branch
504 failed_predicates.put(predicate, true);
506 case SLEEP_FAIL_TYPE2:
507 predicate->incr_fail_count();
508 predicate->incr_sleep_score(1);
509 failed_predicates.put(predicate, true);
511 case SLEEP_FAIL_TYPE3:
512 predicate->incr_fail_count();
513 predicate->decr_sleep_score(10);
516 predicate->incr_sleep_score(10);
519 model_print("unknown predicate result type.\n");
525 bool NewFuzzer::check_predicate_expressions(PredExprSet * pred_expressions,
526 inst_act_map_t * inst_act_map, uint64_t write_val, bool * no_predicate)
528 bool satisfy_predicate = true;
530 PredExprSetIter * pred_expr_it = pred_expressions->iterator();
531 while (pred_expr_it->hasNext()) {
532 struct pred_expr * expression = pred_expr_it->next();
535 switch (expression->token) {
537 *no_predicate = true;
540 FuncInst * to_be_compared;
541 ModelAction * last_act;
544 to_be_compared = expression->func_inst;
545 last_act = inst_act_map->get(to_be_compared);
546 last_read = last_act->get_reads_from_value();
548 equality = (write_val == last_read);
549 if (equality != expression->value)
550 satisfy_predicate = false;
553 equality = ((void*)write_val == NULL);
554 if (equality != expression->value)
555 satisfy_predicate = false;
558 model_print("unknown predicate token\n");
562 if (!satisfy_predicate)
566 return satisfy_predicate;
569 bool NewFuzzer::shouldWait(const ModelAction * act)