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 update_predicate_score(selected_branch, 1);
82 SnapVector<ModelAction *> * pruned_writes = thrd_pruned_writes[thread_id];
83 for (uint i = 0; i < pruned_writes->size(); i++) {
84 rf_set->push_back( (*pruned_writes)[i] );
87 // Reselect a predicate and prune writes
88 Predicate * curr_pred = selected_branch->get_parent();
89 FuncInst * read_inst = thrd_last_func_inst[thread_id];
90 selected_branch = selectBranch(tid, curr_pred, read_inst);
92 FuncNode * func_node = history->get_curr_func_node(tid);
93 inst_act_map_t * inst_act_map = func_node->get_inst_act_map(tid);
94 prune_writes(tid, selected_branch, rf_set, inst_act_map);
96 ASSERT(selected_branch);
100 ASSERT(rf_set->size() != 0);
101 int random_index = random() % rf_set->size();
106 /* Select a random branch from the children of curr_pred
107 * @return The selected branch
109 Predicate * NewFuzzer::selectBranch(thread_id_t tid, Predicate * curr_pred, FuncInst * read_inst)
111 int thread_id = id_to_int(tid);
112 if ( thrd_selected_child_branch.size() <= (uint) thread_id)
113 thrd_selected_child_branch.resize(thread_id + 1);
115 if (curr_pred == NULL || read_inst == NULL) {
116 thrd_selected_child_branch[thread_id] = NULL;
120 ModelVector<Predicate *> * children = curr_pred->get_children();
121 SnapVector<Predicate *> branches;
122 uint32_t numerator = 1;
124 for (uint i = 0; i < children->size(); i++) {
125 Predicate * child = (*children)[i];
126 if (child->get_func_inst() == read_inst && !failed_predicates.contains(child)) {
127 branches.push_back(child);
129 // max of (exploration counts + 1)
130 if (child->get_expl_count() + 1 > numerator)
131 numerator = child->get_expl_count() + 1;
135 // predicate children have not been generated
136 if (branches.size() == 0) {
137 thrd_selected_child_branch[thread_id] = NULL;
141 // randomly select a branch
142 // int random_index = random() % branches.size();
143 // Predicate * random_branch = branches[ random_index ];
145 int index = choose_index(&branches, numerator);
146 Predicate * random_branch = branches[ index ];
147 thrd_selected_child_branch[thread_id] = random_branch;
149 // Update predicate tree position
150 FuncNode * func_node = history->get_curr_func_node(tid);
151 func_node->set_predicate_tree_position(tid, random_branch);
153 return random_branch;
157 * @brief Select a branch from the given predicate branches based
158 * on their exploration counts.
160 * Let b_1, ..., b_n be branches with exploration counts c_1, ..., c_n
161 * M := max(c_1, ..., c_n) + 1
162 * Factor f_i := M / (c_i + 1)
163 * The probability p_i that branch b_i is selected:
164 * p_i := f_i / (f_1 + ... + f_n)
165 * = \fraction{ 1/(c_i + 1) }{ 1/(c_1 + 1) + ... + 1/(c_n + 1) }
167 * Note: (1) c_i + 1 is used because counts may be 0.
168 * (2) The numerator of f_i is chosen to reduce the effect of underflow
170 * @param numerator is M defined above
172 int NewFuzzer::choose_index(SnapVector<Predicate *> * branches, uint32_t numerator)
174 if (branches->size() == 1)
177 double total_factor = 0;
178 SnapVector<double> factors = SnapVector<double>( branches->size() + 1 );
179 for (uint i = 0; i < branches->size(); i++) {
180 Predicate * branch = (*branches)[i];
181 double factor = (double) numerator / (branch->get_expl_count() + 5 * branch->get_fail_count() + 1);
182 total_factor += factor;
183 factors.push_back(factor);
186 double prob = (double) random() / RAND_MAX;
190 for (uint i = 0; i < factors.size(); i++) {
192 prob_sum += (double) (factors[i] / total_factor);
193 if (prob_sum > prob) {
201 Predicate * NewFuzzer::get_selected_child_branch(thread_id_t tid)
203 int thread_id = id_to_int(tid);
204 if (thrd_selected_child_branch.size() <= (uint) thread_id)
207 return thrd_selected_child_branch[thread_id];
210 /* Remove writes from the rf_set that do not satisfie the selected predicate,
211 * and store them in thrd_pruned_writes
213 * @return true if rf_set is pruned
215 bool NewFuzzer::prune_writes(thread_id_t tid, Predicate * pred,
216 SnapVector<ModelAction *> * rf_set, inst_act_map_t * inst_act_map)
221 PredExprSet * pred_expressions = pred->get_pred_expressions();
222 if (pred_expressions->getSize() == 0) // unset predicates
225 int thread_id = id_to_int(tid);
226 uint old_size = thrd_pruned_writes.size();
227 if (thrd_pruned_writes.size() <= (uint) thread_id) {
228 uint new_size = thread_id + 1;
229 thrd_pruned_writes.resize(new_size);
230 for (uint i = old_size; i < new_size; i++)
231 thrd_pruned_writes[i] = new SnapVector<ModelAction *>();
233 SnapVector<ModelAction *> * pruned_writes = thrd_pruned_writes[thread_id];
234 pruned_writes->clear(); // clear the old pruned_writes set
239 while ( index < rf_set->size() ) {
240 ModelAction * write_act = (*rf_set)[index];
241 uint64_t write_val = write_act->get_write_value();
242 bool satisfy_predicate = true;
244 PredExprSetIter * pred_expr_it = pred_expressions->iterator();
245 while (pred_expr_it->hasNext()) {
246 struct pred_expr * expression = pred_expr_it->next();
249 switch (expression->token) {
253 FuncInst * to_be_compared;
254 ModelAction * last_act;
257 to_be_compared = expression->func_inst;
258 last_act = inst_act_map->get(to_be_compared);
259 last_read = last_act->get_reads_from_value();
261 equality = (write_val == last_read);
262 if (equality != expression->value)
263 satisfy_predicate = false;
266 equality = ((void*)write_val == NULL);
267 if (equality != expression->value)
268 satisfy_predicate = false;
271 model_print("unknown predicate token\n");
275 if (!satisfy_predicate)
279 if (!satisfy_predicate) {
280 ASSERT(rf_set != NULL);
281 (*rf_set)[index] = rf_set->back();
283 pruned_writes->push_back(write_act);
292 /* @brief Put a thread to sleep because no writes in rf_set satisfies the selected predicate.
294 * @param thread A thread whose last action is a read
296 void NewFuzzer::conditional_sleep(Thread * thread)
298 int index = paused_thread_list.size();
300 model->getScheduler()->add_sleep(thread);
301 paused_thread_list.push_back(thread);
302 paused_thread_table.put(thread, index); // Update table
304 /* Add the waiting condition to ModelHistory */
305 ModelAction * read = thread->get_pending();
306 thread_id_t tid = thread->get_id();
307 FuncNode * func_node = history->get_curr_func_node(tid);
308 inst_act_map_t * inst_act_map = func_node->get_inst_act_map(tid);
310 Predicate * selected_branch = get_selected_child_branch(tid);
311 ConcretePredicate * concrete = selected_branch->evaluate(inst_act_map, tid);
312 concrete->set_location(read->get_location());
314 history->add_waiting_write(concrete);
315 /* history->add_waiting_thread is already called in find_threads */
318 bool NewFuzzer::has_paused_threads()
320 return paused_thread_list.size() != 0;
323 Thread * NewFuzzer::selectThread(int * threadlist, int numthreads)
325 if (numthreads == 0 && has_paused_threads()) {
326 wake_up_paused_threads(threadlist, &numthreads);
327 //model_print("list size: %d, active t id: %d\n", numthreads, threadlist[0]);
330 int random_index = random() % numthreads;
331 int thread = threadlist[random_index];
332 thread_id_t curr_tid = int_to_id(thread);
333 return execution->get_thread(curr_tid);
336 /* Force waking up one of threads paused by Fuzzer, because otherwise
337 * the Fuzzer is not making progress
339 void NewFuzzer::wake_up_paused_threads(int * threadlist, int * numthreads)
341 int random_index = random() % paused_thread_list.size();
342 Thread * thread = paused_thread_list[random_index];
343 model->getScheduler()->remove_sleep(thread);
345 Thread * last_thread = paused_thread_list.back();
346 paused_thread_list[random_index] = last_thread;
347 paused_thread_list.pop_back();
348 paused_thread_table.put(last_thread, random_index); // Update table
349 paused_thread_table.remove(thread);
351 thread_id_t tid = thread->get_id();
352 history->remove_waiting_write(tid);
353 history->remove_waiting_thread(tid);
355 threadlist[*numthreads] = tid;
358 Predicate * selected_branch = get_selected_child_branch(tid);
359 update_predicate_score(selected_branch, 3);
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 Predicate * selected_branch = get_selected_child_branch(tid);
383 update_predicate_score(selected_branch, 4);
385 model_print("** thread %d is woken up\n", tid);
388 /* Find threads that may write values that the pending read action is waiting for
389 * @return True if any thread is found
391 bool NewFuzzer::find_threads(ModelAction * pending_read)
393 ASSERT(pending_read->is_read());
395 void * location = pending_read->get_location();
396 thread_id_t self_id = pending_read->get_tid();
397 bool finds_waiting_for = false;
399 SnapVector<FuncNode *> * func_node_list = history->getWrFuncNodes(location);
400 for (uint i = 0; i < func_node_list->size(); i++) {
401 FuncNode * target_node = (*func_node_list)[i];
402 for (uint i = 1; i < execution->get_num_threads(); i++) {
403 thread_id_t tid = int_to_id(i);
407 FuncNode * node = history->get_curr_func_node(tid);
408 /* It is possible that thread tid is not in any FuncNode */
412 int distance = node->compute_distance(target_node);
413 if (distance != -1) {
414 history->add_waiting_thread(self_id, tid, target_node, distance);
415 finds_waiting_for = true;
416 //model_print("thread: %d; distance from node %d to node %d: %d\n", tid, node->get_func_id(), target_node->get_func_id(), distance);
421 return finds_waiting_for;
424 /* Update predicate counts and scores (asynchronous) when the read value is not available
427 * type 1: find_threads return false
428 * type 2: find_threads return true, but the fuzzer decides that that thread shall not sleep based on sleep score
429 * type 3: threads are put to sleep but woken up before the waited value appears
430 * type 4: threads are put to sleep and the waited vaule appears (success)
432 void NewFuzzer::update_predicate_score(Predicate * predicate, int type)
436 predicate->incr_fail_count();
438 /* Do not choose this predicate when reselecting a new branch */
439 failed_predicates.put(predicate, true);
441 predicate->incr_fail_count();
442 predicate->decr_sleep_score(1);
444 predicate->incr_fail_count();
445 predicate->incr_sleep_score(10);
447 predicate->decr_sleep_score(10);
451 bool NewFuzzer::shouldWait(const ModelAction * act)