9d061bbf9a857d41938bb7394d00d18e4bffed1b
[c11tester.git] / newfuzzer.cc
1 #include "newfuzzer.h"
2 #include "threads-model.h"
3 #include "action.h"
4 #include "history.h"
5 #include "funcnode.h"
6 #include "funcinst.h"
7 #include "concretepredicate.h"
8 #include "waitobj.h"
9
10 #include "model.h"
11 #include "schedule.h"
12 #include "execution.h"
13
14 NewFuzzer::NewFuzzer() :
15         thrd_last_read_act(),
16         thrd_last_func_inst(),
17         thrd_selected_child_branch(),
18         thrd_pruned_writes(),
19         paused_thread_list(),
20         paused_thread_table(128),
21         failed_predicates(32),
22         dist_info_vec()
23 {}
24
25 /**
26  * @brief Register the ModelHistory and ModelExecution engine
27  */
28 void NewFuzzer::register_engine(ModelHistory * history, ModelExecution *execution)
29 {
30         this->history = history;
31         this->execution = execution;
32 }
33
34 int NewFuzzer::selectWrite(ModelAction *read, SnapVector<ModelAction *> * rf_set)
35 {
36 //      return random() % rf_set->size();
37
38         thread_id_t tid = read->get_tid();
39         int thread_id = id_to_int(tid);
40
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);
44         }
45
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);
52
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);
56
57                 if (!failed_predicates.isEmpty())
58                         failed_predicates.reset();
59
60                 thrd_last_read_act[thread_id] = read;
61                 thrd_last_func_inst[thread_id] = read_inst;
62         }
63
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);
67
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());
69
70 /*--
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();
75
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;
82                 } else {
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);
86                         }
87
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();
92
93                         conditional_sleep(read_thread);
94                         // Returning -1 stops the while loop of ModelExecution::process_read
95                         return -1;      
96                 }
97 */
98
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] );
102                 }
103
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);
108
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);
112
113                 ASSERT(selected_branch);
114         }
115
116         ASSERT(rf_set->size() != 0);
117         int random_index = random() % rf_set->size();
118
119         return random_index;
120 }
121
122 void NewFuzzer::check_store_visibility(Predicate * curr_pred, FuncInst * read_inst,
123         inst_act_map_t * inst_act_map, SnapVector<ModelAction *> * rf_set)
124 {
125         ASSERT(!rf_set->empty());
126         if (curr_pred == NULL || read_inst == NULL)
127                 return;
128
129         ModelVector<Predicate *> * children = curr_pred->get_children();
130
131         /* Iterate over all predicate children */
132         for (uint i = 0; i < children->size(); i++) {
133                 Predicate * branch = (*children)[i];
134
135                 /* The children predicates may have different FuncInsts */
136                 if (branch->get_func_inst() == read_inst) {
137                         PredExprSet * pred_expressions = branch->get_pred_expressions();
138
139                         /* Do not check unset predicates */
140                         if (pred_expressions->isEmpty())
141                                 continue;
142
143                         branch->incr_total_checking_count();
144
145                         /* Iterate over all write actions */
146                         for (uint j = 0; j < rf_set->size(); j++) {
147                                 ModelAction * write_act = (*rf_set)[j];
148                                 uint64_t write_val = write_act->get_write_value();
149                                 bool dummy = true;
150                                 bool satisfy_predicate = check_predicate_expressions(pred_expressions, inst_act_map, write_val, &dummy);
151
152                                 /* If one write value satisfies the predicate, go to check the next predicate */
153                                 if (satisfy_predicate) {
154                                         branch->incr_store_visible_count();
155                                         break;
156                                 }
157                         }
158                 }
159
160         }
161 }
162
163
164 /* Select a random branch from the children of curr_pred 
165  * @return The selected branch
166  */
167 Predicate * NewFuzzer::selectBranch(thread_id_t tid, Predicate * curr_pred, FuncInst * read_inst)
168 {
169         int thread_id = id_to_int(tid);
170         if ( thrd_selected_child_branch.size() <= (uint) thread_id)
171                 thrd_selected_child_branch.resize(thread_id + 1);
172
173         if (curr_pred == NULL || read_inst == NULL) {
174                 thrd_selected_child_branch[thread_id] = NULL;
175                 return NULL;
176         }
177
178         ModelVector<Predicate *> * children = curr_pred->get_children();
179         SnapVector<Predicate *> branches;
180
181         for (uint i = 0; i < children->size(); i++) {
182                 Predicate * child = (*children)[i];
183                 if (child->get_func_inst() == read_inst && !failed_predicates.contains(child)) {
184                         branches.push_back(child);
185
186                         /*-- max of (exploration counts + 1)
187                         if (child->get_expl_count() + 1 > numerator)
188                                 numerator = child->get_expl_count() + 1;
189                         */
190                 }
191         }
192
193         // predicate children have not been generated
194         if (branches.size() == 0) {
195                 thrd_selected_child_branch[thread_id] = NULL;
196                 return NULL;
197         }
198
199         int index = choose_index(&branches, 0);
200         Predicate * random_branch = branches[ index ];
201         thrd_selected_child_branch[thread_id] = random_branch;
202
203         // Update predicate tree position
204         FuncNode * func_node = history->get_curr_func_node(tid);
205         func_node->set_predicate_tree_position(tid, random_branch);
206
207         return random_branch;
208 }
209
210 /**
211  * @brief Select a branch from the given predicate branches based
212  * on their exploration counts.
213  *
214  * Let b_1, ..., b_n be branches with exploration counts c_1, ..., c_n
215  * M := max(c_1, ..., c_n) + 1
216  * Factor f_i := M / (c_i + 1)
217  * The probability p_i that branch b_i is selected:
218  *      p_i := f_i / (f_1 + ... + f_n)
219  *           = \fraction{ 1/(c_i + 1) }{ 1/(c_1 + 1) + ... + 1/(c_n + 1) }
220  *
221  * Note: (1) c_i + 1 is used because counts may be 0.
222  *       (2) The numerator of f_i is chosen to reduce the effect of underflow
223  *      
224  * @param numerator is M defined above
225  */
226 int NewFuzzer::choose_index(SnapVector<Predicate *> * branches, uint32_t numerator)
227 {
228         return random() % branches->size();
229 /*--
230         if (branches->size() == 1)
231                 return 0;
232
233         double total_factor = 0;
234         SnapVector<double> factors = SnapVector<double>( branches->size() + 1 );
235         for (uint i = 0; i < branches->size(); i++) {
236                 Predicate * branch = (*branches)[i];
237                 double factor = (double) numerator / (branch->get_expl_count() + 5 * branch->get_fail_count() + 1);
238                 total_factor += factor;
239                 factors.push_back(factor);
240         }
241
242         double prob = (double) random() / RAND_MAX;
243         double prob_sum = 0;
244         int index = 0;
245
246         for (uint i = 0; i < factors.size(); i++) {
247                 index = i;
248                 prob_sum += (double) (factors[i] / total_factor);
249                 if (prob_sum > prob) {
250                         break;
251                 }
252         }
253
254         return index;
255 */
256 }
257
258 Predicate * NewFuzzer::get_selected_child_branch(thread_id_t tid)
259 {
260         int thread_id = id_to_int(tid);
261         if (thrd_selected_child_branch.size() <= (uint) thread_id)
262                 return NULL;
263
264         return thrd_selected_child_branch[thread_id];
265 }
266
267 /* Remove writes from the rf_set that do not satisfie the selected predicate, 
268  * and store them in thrd_pruned_writes
269  *
270  * @return true if rf_set is pruned
271  */
272 bool NewFuzzer::prune_writes(thread_id_t tid, Predicate * pred,
273         SnapVector<ModelAction *> * rf_set, inst_act_map_t * inst_act_map)
274 {
275         if (pred == NULL)
276                 return false;
277
278         PredExprSet * pred_expressions = pred->get_pred_expressions();
279         if (pred_expressions->getSize() == 0)   // unset predicates
280                 return false;
281
282         int thread_id = id_to_int(tid);
283         uint old_size = thrd_pruned_writes.size();
284         if (thrd_pruned_writes.size() <= (uint) thread_id) {
285                 uint new_size = thread_id + 1;
286                 thrd_pruned_writes.resize(new_size);
287                 for (uint i = old_size; i < new_size; i++)
288                         thrd_pruned_writes[i] = new SnapVector<ModelAction *>();
289         }
290         SnapVector<ModelAction *> * pruned_writes = thrd_pruned_writes[thread_id];
291         pruned_writes->clear(); // clear the old pruned_writes set
292
293         bool pruned = false;
294         uint index = 0;
295
296         while ( index < rf_set->size() ) {
297                 ModelAction * write_act = (*rf_set)[index];
298                 uint64_t write_val = write_act->get_write_value();
299                 bool no_predicate = false;
300                 bool satisfy_predicate = check_predicate_expressions(pred_expressions, inst_act_map, write_val, &no_predicate);
301
302                 if (no_predicate)
303                         return false;
304
305                 if (!satisfy_predicate) {
306                         ASSERT(rf_set != NULL);
307                         (*rf_set)[index] = rf_set->back();
308                         rf_set->pop_back();
309                         pruned_writes->push_back(write_act);
310                         pruned = true;
311                 } else
312                         index++;
313         }
314
315         return pruned;
316 }
317
318 /* @brief Put a thread to sleep because no writes in rf_set satisfies the selected predicate. 
319  *
320  * @param thread A thread whose last action is a read
321  */
322 void NewFuzzer::conditional_sleep(Thread * thread)
323 {
324         int index = paused_thread_list.size();
325
326         model->getScheduler()->add_sleep(thread);
327         paused_thread_list.push_back(thread);
328         paused_thread_table.put(thread, index); // Update table
329
330         /* Add the waiting condition to ModelHistory */
331         ModelAction * read = thread->get_pending();
332         thread_id_t tid = thread->get_id();
333         FuncNode * func_node = history->get_curr_func_node(tid);
334         inst_act_map_t * inst_act_map = func_node->get_inst_act_map(tid);
335
336         Predicate * selected_branch = get_selected_child_branch(tid);
337         ConcretePredicate * concrete = selected_branch->evaluate(inst_act_map, tid);
338         concrete->set_location(read->get_location());
339
340         history->add_waiting_write(concrete);
341         /* history->add_waiting_thread is already called in find_threads */
342 }
343
344 /**
345  * Decides whether a thread should condition sleep based on
346  * the sleep score of the chosen predicate.
347  *
348  * sleep_score = 0: never sleeps
349  * sleep_score = 100: always sleeps
350  **/
351 bool NewFuzzer::should_conditional_sleep(Predicate * predicate)
352 {
353         return false;
354         /*
355         int sleep_score = predicate->get_sleep_score();
356         int random_num = random() % 100;
357
358         // should sleep if random_num falls within [0, sleep_score)
359         if (random_num < sleep_score)
360                 return true;
361
362         return false;
363         */
364 }
365
366 bool NewFuzzer::has_paused_threads()
367 {
368         return paused_thread_list.size() != 0;
369 }
370
371 Thread * NewFuzzer::selectThread(int * threadlist, int numthreads)
372 {
373         if (numthreads == 0 && has_paused_threads()) {
374                 wake_up_paused_threads(threadlist, &numthreads);
375                 //model_print("list size: %d, active t id: %d\n", numthreads, threadlist[0]);
376         }
377
378         int random_index = random() % numthreads;
379         int thread = threadlist[random_index];
380         thread_id_t curr_tid = int_to_id(thread);
381         return execution->get_thread(curr_tid);
382 }
383
384 /* Force waking up one of threads paused by Fuzzer, because otherwise
385  * the Fuzzer is not making progress
386  */
387 void NewFuzzer::wake_up_paused_threads(int * threadlist, int * numthreads)
388 {
389         int random_index = random() % paused_thread_list.size();
390         Thread * thread = paused_thread_list[random_index];
391         model->getScheduler()->remove_sleep(thread);
392
393         Thread * last_thread = paused_thread_list.back();
394         paused_thread_list[random_index] = last_thread;
395         paused_thread_list.pop_back();
396         paused_thread_table.put(last_thread, random_index);     // Update table
397         paused_thread_table.remove(thread);
398
399         thread_id_t tid = thread->get_id();
400         history->remove_waiting_write(tid);
401         history->remove_waiting_thread(tid);
402
403         threadlist[*numthreads] = tid;
404         (*numthreads)++;
405
406 /*--
407         Predicate * selected_branch = get_selected_child_branch(tid);
408         update_predicate_score(selected_branch, SLEEP_FAIL_TYPE3);
409 */
410
411         model_print("thread %d is woken up\n", tid);
412 }
413
414 /* Wake up conditional sleeping threads if the desired write is available */
415 void NewFuzzer::notify_paused_thread(Thread * thread)
416 {
417         ASSERT(paused_thread_table.contains(thread));
418
419         int index = paused_thread_table.get(thread);
420         model->getScheduler()->remove_sleep(thread);
421
422         Thread * last_thread = paused_thread_list.back();
423         paused_thread_list[index] = last_thread;
424         paused_thread_list.pop_back();
425         paused_thread_table.put(last_thread, index);    // Update table
426         paused_thread_table.remove(thread);
427
428         thread_id_t tid = thread->get_id();
429         history->remove_waiting_write(tid);
430         history->remove_waiting_thread(tid);
431
432 /*--
433         Predicate * selected_branch = get_selected_child_branch(tid);
434         update_predicate_score(selected_branch, SLEEP_SUCCESS);
435 */
436
437         model_print("** thread %d is woken up\n", tid);
438 }
439
440 /* Find threads that may write values that the pending read action is waiting for.
441  * Side effect: waiting thread related info are stored in dist_info_vec
442  *
443  * @return True if any thread is found
444  */
445 bool NewFuzzer::find_threads(ModelAction * pending_read)
446 {
447         ASSERT(pending_read->is_read());
448
449         void * location = pending_read->get_location();
450         thread_id_t self_id = pending_read->get_tid();
451         bool finds_waiting_for = false;
452
453         SnapVector<FuncNode *> * func_node_list = history->getWrFuncNodes(location);
454         for (uint i = 0; i < func_node_list->size(); i++) {
455                 FuncNode * target_node = (*func_node_list)[i];
456                 for (uint i = 1; i < execution->get_num_threads(); i++) {
457                         thread_id_t tid = int_to_id(i);
458                         if (tid == self_id)
459                                 continue;
460
461                         FuncNode * node = history->get_curr_func_node(tid);
462                         /* It is possible that thread tid is not in any FuncNode */
463                         if (node == NULL)
464                                 continue;
465
466                         int distance = node->compute_distance(target_node);
467                         if (distance != -1) {
468                                 finds_waiting_for = true;
469                                 //model_print("thread: %d; distance from node %d to node %d: %d\n", tid, node->get_func_id(), target_node->get_func_id(), distance);
470
471                                 dist_info_vec.push_back(node_dist_info(tid, target_node, distance));
472                         }
473                 }
474         }
475
476         return finds_waiting_for;
477 }
478
479 /* Update predicate counts and scores (asynchronous) when the read value is not available
480  *
481  * @param type
482  *        type 1: find_threads return false
483  *        type 2: find_threads return true, but the fuzzer decides that that thread shall not sleep based on sleep score
484  *        type 3: threads are put to sleep but woken up before the waited value appears
485  *        type 4: threads are put to sleep and the waited vaule appears (success)
486  */
487
488 /*--
489 void NewFuzzer::update_predicate_score(Predicate * predicate, sleep_result_t type)
490 {
491         switch (type) {
492                 case SLEEP_FAIL_TYPE1:
493                         predicate->incr_fail_count();
494
495                         // Do not choose this predicate when reselecting a new branch
496                         failed_predicates.put(predicate, true);
497                         break;
498                 case SLEEP_FAIL_TYPE2:
499                         predicate->incr_fail_count();
500                         predicate->incr_sleep_score(1);
501                         failed_predicates.put(predicate, true);
502                         break;
503                 case SLEEP_FAIL_TYPE3:
504                         predicate->incr_fail_count();
505                         predicate->decr_sleep_score(10);
506                         break;
507                 case SLEEP_SUCCESS:
508                         predicate->incr_sleep_score(10);
509                         break;
510                 default:
511                         model_print("unknown predicate result type.\n");
512                         break;
513         }
514 }
515 */
516
517 bool NewFuzzer::check_predicate_expressions(PredExprSet * pred_expressions,
518         inst_act_map_t * inst_act_map, uint64_t write_val, bool * no_predicate)
519 {
520         bool satisfy_predicate = true;
521
522         PredExprSetIter * pred_expr_it = pred_expressions->iterator();
523         while (pred_expr_it->hasNext()) {
524                 struct pred_expr * expression = pred_expr_it->next();
525                 bool equality;
526
527                 switch (expression->token) {
528                         case NOPREDICATE:
529                                 *no_predicate = true;
530                                 break;
531                         case EQUALITY:
532                                 FuncInst * to_be_compared;
533                                 ModelAction * last_act;
534                                 uint64_t last_read;
535
536                                 to_be_compared = expression->func_inst;
537                                 last_act = inst_act_map->get(to_be_compared);
538                                 last_read = last_act->get_reads_from_value();
539
540                                 equality = (write_val == last_read);
541                                 if (equality != expression->value)
542                                         satisfy_predicate = false;
543                                 break;
544                         case NULLITY:
545                                 equality = ((void*)write_val == NULL);
546                                 if (equality != expression->value)
547                                         satisfy_predicate = false;
548                                 break;
549                         default:
550                                 model_print("unknown predicate token\n");
551                                 break;
552                 }
553
554                 if (!satisfy_predicate)
555                         break;
556         }
557
558         return satisfy_predicate;
559 }
560
561 bool NewFuzzer::shouldWait(const ModelAction * act)
562 {
563         return random() & 1;
564 }