funcnode.cc

   1 #include "action.h"
   2 #include "history.h"
   3 #include "funcnode.h"
   4 #include "funcinst.h"
   5 #include "predicate.h"
   6 #include "concretepredicate.h"
   7
   8 #include "model.h"
   9 #include <cmath>
  10
  11 FuncNode::FuncNode(ModelHistory * history) :
  12         history(history),
  13         exit_count(0),
  14         marker(1),
  15         func_inst_map(),
  16         inst_list(),
  17         entry_insts(),
  18         inst_pred_map(128),
  19         inst_id_map(128),
  20         loc_act_map(128),
  21         predicate_tree_position(),
  22         predicate_leaves(),
  23         leaves_tmp_storage(),
  24         weight_debug_vec(),
  25         failed_predicates(),
  26         edge_table(32),
  27         out_edges()
  28 {
  29         predicate_tree_entry = new Predicate(NULL, true);
  30         predicate_tree_entry->add_predicate_expr(NOPREDICATE, NULL, true);
  31
  32         predicate_tree_exit = new Predicate(NULL, false, true);
  33         predicate_tree_exit->set_depth(MAX_DEPTH);
  34
  35         /* Snapshot data structures below */
  36         action_list_buffer = new SnapList<action_list_t *>();
  37         read_locations = new loc_set_t();
  38         write_locations = new loc_set_t();
  39         val_loc_map = new HashTable<uint64_t, loc_set_t *, uint64_t, 0, snapshot_malloc, snapshot_calloc, snapshot_free, int64_hash>();
  40         loc_may_equal_map = new HashTable<void *, loc_set_t *, uintptr_t, 0>();
  41
  42         //values_may_read_from = new value_set_t();
  43 }
  44
  45 /* Reallocate snapshotted memories when new executions start */
  46 void FuncNode::set_new_exec_flag()
  47 {
  48         action_list_buffer = new SnapList<action_list_t *>();
  49         read_locations = new loc_set_t();
  50         write_locations = new loc_set_t();
  51         val_loc_map = new HashTable<uint64_t, loc_set_t *, uint64_t, 0, snapshot_malloc, snapshot_calloc, snapshot_free, int64_hash>();
  52         loc_may_equal_map = new HashTable<void *, loc_set_t *, uintptr_t, 0>();
  53
  54         //values_may_read_from = new value_set_t();
  55 }
  56
  57 /* Check whether FuncInst with the same type, position, and location
  58  * as act has been added to func_inst_map or not. If not, add it.
  59  */
  60 void FuncNode::add_inst(ModelAction *act)
  61 {
  62         ASSERT(act);
  63         const char * position = act->get_position();
  64
  65         /* THREAD* actions, ATOMIC_LOCK, ATOMIC_TRYLOCK, and ATOMIC_UNLOCK
  66          * actions are not tagged with their source line numbers
  67          */
  68         if (position == NULL)
  69                 return;
  70
  71         FuncInst * func_inst = func_inst_map.get(position);
  72
  73         /* This position has not been inserted into hashtable before */
  74         if (func_inst == NULL) {
  75                 func_inst = create_new_inst(act);
  76                 func_inst_map.put(position, func_inst);
  77                 return;
  78         }
  79
  80         /* Volatile variables that use ++ or -- syntax may result in read and write actions with the same position */
  81         if (func_inst->get_type() != act->get_type()) {
  82                 FuncInst * collision_inst = func_inst->search_in_collision(act);
  83
  84                 if (collision_inst == NULL) {
  85                         collision_inst = create_new_inst(act);
  86                         func_inst->add_to_collision(collision_inst);
  87                         return;
  88                 } else {
  89                         func_inst = collision_inst;
  90                 }
  91         }
  92
  93         ASSERT(func_inst->get_type() == act->get_type());
  94         int curr_execution_number = model->get_execution_number();
  95
  96         /* Reset locations when new executions start */
  97         if (func_inst->get_execution_number() != curr_execution_number) {
  98                 func_inst->set_location(act->get_location());
  99                 func_inst->set_execution_number(curr_execution_number);
 100         }
 101
 102         /* Mark the memory location of such inst as not unique */
 103         if (func_inst->get_location() != act->get_location())
 104                 func_inst->not_single_location();
 105 }
 106
 107 FuncInst * FuncNode::create_new_inst(ModelAction * act)
 108 {
 109         FuncInst * func_inst = new FuncInst(act, this);
 110         int exec_num = model->get_execution_number();
 111         func_inst->set_execution_number(exec_num);
 112
 113         inst_list.push_back(func_inst);
 114
 115         return func_inst;
 116 }
 117
 118
 119 /* Get the FuncInst with the same type, position, and location
 120  * as act
 121  *
 122  * @return FuncInst with the same type, position, and location as act */
 123 FuncInst * FuncNode::get_inst(ModelAction *act)
 124 {
 125         ASSERT(act);
 126         const char * position = act->get_position();
 127
 128         /* THREAD* actions, ATOMIC_LOCK, ATOMIC_TRYLOCK, and ATOMIC_UNLOCK
 129          * actions are not tagged with their source line numbers
 130          */
 131         if (position == NULL)
 132                 return NULL;
 133
 134         FuncInst * inst = func_inst_map.get(position);
 135         if (inst == NULL)
 136                 return NULL;
 137
 138         action_type inst_type = inst->get_type();
 139         action_type act_type = act->get_type();
 140
 141         if (inst_type == act_type) {
 142                 return inst;
 143         }
 144         /* RMWRCAS actions are converted to RMW or READ actions */
 145         else if (inst_type == ATOMIC_RMWRCAS &&
 146                                          (act_type == ATOMIC_RMW || act_type == ATOMIC_READ)) {
 147                 return inst;
 148         }
 149         /* Return the FuncInst in the collision list */
 150         else {
 151                 return inst->search_in_collision(act);
 152         }
 153 }
 154
 155
 156 void FuncNode::add_entry_inst(FuncInst * inst)
 157 {
 158         if (inst == NULL)
 159                 return;
 160
 161         mllnode<FuncInst *> * it;
 162         for (it = entry_insts.begin();it != NULL;it = it->getNext()) {
 163                 if (inst == it->getVal())
 164                         return;
 165         }
 166
 167         entry_insts.push_back(inst);
 168 }
 169
 170 /**
 171  * @brief Convert ModelAdtion list to FuncInst list
 172  * @param act_list A list of ModelActions
 173  */
 174 void FuncNode::update_tree(action_list_t * act_list)
 175 {
 176         if (act_list == NULL || act_list->size() == 0)
 177                 return;
 178
 179         HashTable<void *, value_set_t *, uintptr_t, 0> * write_history = history->getWriteHistory();
 180
 181         /* build inst_list from act_list for later processing */
 182         func_inst_list_t inst_list;
 183         action_list_t rw_act_list;
 184
 185         for (sllnode<ModelAction *> * it = act_list->begin();it != NULL;it = it->getNext()) {
 186                 ModelAction * act = it->getVal();
 187
 188                 // Only ATOMIC_RMW or ATOMIC_WRITE may be swapped with their original types,
 189                 // which are later added to rw_act_list. Therefore, it is safe to only revert
 190                 // back action types for actions in rw_act_list whose types have been swapped.
 191                 if (act->get_original_type() != ATOMIC_NOP && act->get_swap_flag() == false)
 192                         act->use_original_type();
 193
 194                 // Remove func_act_ref so that actions can be deleted by Execution::collectActions
 195                 act->setFuncActRef(NULL);
 196                 if (act->is_read()) {
 197                         // For every read or rmw actions in this list, the reads_from is not deleted.
 198                         // So it is safe to call get_reads_from
 199                         ModelAction * rf = act->get_reads_from();
 200                         rf->setFuncActRef(NULL);
 201                 }
 202
 203                 FuncInst * func_inst = get_inst(act);
 204                 void * loc = act->get_location();
 205
 206                 if (func_inst == NULL)
 207                         continue;
 208
 209                 inst_list.push_back(func_inst);
 210                 bool act_added = false;
 211
 212                 if (act->is_write()) {
 213                         rw_act_list.push_back(act);
 214                         act_added = true;
 215                         if (!write_locations->contains(loc)) {
 216                                 write_locations->add(loc);
 217                                 history->update_loc_wr_func_nodes_map(loc, this);
 218                         }
 219                 }
 220
 221                 if (act->is_read()) {
 222                         if (!act_added)
 223                                 rw_act_list.push_back(act);
 224
 225                         /* If func_inst may only read_from a single location, then:
 226                          *
 227                          * The first time an action reads from some location,
 228                          * import all the values that have been written to this
 229                          * location from ModelHistory and notify ModelHistory
 230                          * that this FuncNode may read from this location.
 231                          */
 232                         if (!read_locations->contains(loc) && func_inst->is_single_location()) {
 233                                 read_locations->add(loc);
 234                                 value_set_t * write_values = write_history->get(loc);
 235                                 add_to_val_loc_map(write_values, loc);
 236                                 history->update_loc_rd_func_nodes_map(loc, this);
 237                         }
 238                 }
 239         }
 240
 241         update_inst_tree(&inst_list);
 242         update_predicate_tree(&rw_act_list);
 243
 244         // Revert back action types and free
 245         for (sllnode<ModelAction *> * it = act_list->begin(); it != NULL; it = it->getNext()) {
 246                 ModelAction * act = it->getVal();
 247
 248                 // Revert back action types for actions whose types have been changed.
 249                 if (act->get_swap_flag() == true)
 250                         act->use_original_type();
 251
 252                 /**  Free actions
 253                  * case 1. READY_FREE -> delete
 254                  * case 2. Read action whose read from is READY_FREE -> delete both actions
 255                  * In both cases, the actions have already been removed from core model
 256                  * action lists.
 257                  */
 258
 259                 /* Problematic: could double free actions
 260                 if (act->is_free()) {
 261                         model_print("delete free act %d\n", act->get_seq_number());
 262                         delete act;
 263                 } else if (act->is_read()) {
 264                         ModelAction * rf = act->get_reads_from();
 265                         if (rf->is_free()) {
 266                                 model_print("delete act %d\n", act->get_seq_number());
 267                                 model_print("delete act %d\n", rf->get_seq_number());
 268                                 delete rf;
 269                                 delete act;
 270                         }
 271                 }*/
 272         }
 273
 274 //      print_predicate_tree();
 275 }
 276
 277 /**
 278  * @brief Link FuncInsts in inst_list  - add one FuncInst to another's predecessors and successors
 279  * @param inst_list A list of FuncInsts
 280  */
 281 void FuncNode::update_inst_tree(func_inst_list_t * inst_list)
 282 {
 283         if (inst_list == NULL)
 284                 return;
 285         else if (inst_list->size() == 0)
 286                 return;
 287
 288         /* start linking */
 289         sllnode<FuncInst *>* it = inst_list->begin();
 290         sllnode<FuncInst *>* prev;
 291
 292         /* add the first instruction to the list of entry insts */
 293         FuncInst * entry_inst = it->getVal();
 294         add_entry_inst(entry_inst);
 295
 296         it = it->getNext();
 297         while (it != NULL) {
 298                 prev = it->getPrev();
 299
 300                 FuncInst * prev_inst = prev->getVal();
 301                 FuncInst * curr_inst = it->getVal();
 302
 303                 prev_inst->add_succ(curr_inst);
 304                 curr_inst->add_pred(prev_inst);
 305
 306                 it = it->getNext();
 307         }
 308 }
 309
 310 void FuncNode::update_predicate_tree(action_list_t * act_list)
 311 {
 312         if (act_list == NULL || act_list->size() == 0)
 313                 return;
 314
 315         incr_marker();
 316         uint32_t inst_counter = 0;
 317
 318         // Clear hashtables
 319         loc_act_map.reset();
 320         inst_pred_map.reset();
 321         inst_id_map.reset();
 322
 323         // Clear the set of leaves encountered in this path
 324         leaves_tmp_storage.clear();
 325
 326         sllnode<ModelAction *> *it = act_list->begin();
 327         Predicate * curr_pred = predicate_tree_entry;
 328         while (it != NULL) {
 329                 ModelAction * next_act = it->getVal();
 330                 FuncInst * next_inst = get_inst(next_act);
 331                 next_inst->set_associated_act(next_act, marker);
 332
 333                 Predicate * unset_predicate = NULL;
 334                 bool branch_found = follow_branch(&curr_pred, next_inst, next_act, &unset_predicate);
 335
 336                 // A branch with unset predicate expression is detected
 337                 if (!branch_found && unset_predicate != NULL) {
 338                         bool amended = amend_predicate_expr(curr_pred, next_inst, next_act);
 339                         if (amended)
 340                                 continue;
 341                         else {
 342                                 curr_pred = unset_predicate;
 343                                 branch_found = true;
 344                         }
 345                 }
 346
 347                 // Detect loops
 348                 if (!branch_found && inst_id_map.contains(next_inst)) {
 349                         FuncInst * curr_inst = curr_pred->get_func_inst();
 350                         uint32_t curr_id = inst_id_map.get(curr_inst);
 351                         uint32_t next_id = inst_id_map.get(next_inst);
 352
 353                         if (curr_id >= next_id) {
 354                                 Predicate * old_pred = inst_pred_map.get(next_inst);
 355                                 Predicate * back_pred = old_pred->get_parent();
 356
 357                                 // For updating weights
 358                                 leaves_tmp_storage.push_back(curr_pred);
 359
 360                                 // Add to the set of backedges
 361                                 curr_pred->add_backedge(back_pred);
 362                                 curr_pred = back_pred;
 363                                 continue;
 364                         }
 365                 }
 366
 367                 // Generate new branches
 368                 if (!branch_found) {
 369                         SnapVector<struct half_pred_expr *> half_pred_expressions;
 370                         infer_predicates(next_inst, next_act, &half_pred_expressions);
 371                         generate_predicates(curr_pred, next_inst, &half_pred_expressions);
 372                         continue;
 373                 }
 374
 375                 if (next_act->is_write())
 376                         curr_pred->set_write(true);
 377
 378                 if (next_act->is_read()) {
 379                         /* Only need to store the locations of read actions */
 380                         loc_act_map.put(next_act->get_location(), next_act);
 381                 }
 382
 383                 inst_pred_map.put(next_inst, curr_pred);
 384                 if (!inst_id_map.contains(next_inst))
 385                         inst_id_map.put(next_inst, inst_counter++);
 386
 387                 it = it->getNext();
 388                 curr_pred->incr_expl_count();
 389         }
 390
 391         if (curr_pred->get_exit() == NULL) {
 392                 // Exit predicate is unset yet
 393                 curr_pred->set_exit(predicate_tree_exit);
 394         }
 395
 396         leaves_tmp_storage.push_back(curr_pred);
 397         update_predicate_tree_weight();
 398 }
 399
 400 /* Given curr_pred and next_inst, find the branch following curr_pred that
 401  * contains next_inst and the correct predicate.
 402  * @return true if branch found, false otherwise.
 403  */
 404 bool FuncNode::follow_branch(Predicate ** curr_pred, FuncInst * next_inst,
 405                                                                                                                  ModelAction * next_act, Predicate ** unset_predicate)
 406 {
 407         /* Check if a branch with func_inst and corresponding predicate exists */
 408         bool branch_found = false;
 409         ModelVector<Predicate *> * branches = (*curr_pred)->get_children();
 410         for (uint i = 0;i < branches->size();i++) {
 411                 Predicate * branch = (*branches)[i];
 412                 if (branch->get_func_inst() != next_inst)
 413                         continue;
 414
 415                 /* Check against predicate expressions */
 416                 bool predicate_correct = true;
 417                 PredExprSet * pred_expressions = branch->get_pred_expressions();
 418
 419                 /* Only read and rmw actions my have unset predicate expressions */
 420                 if (pred_expressions->getSize() == 0) {
 421                         predicate_correct = false;
 422                         if (*unset_predicate == NULL)
 423                                 *unset_predicate = branch;
 424                         else
 425                                 ASSERT(false);
 426
 427                         continue;
 428                 }
 429
 430                 PredExprSetIter * pred_expr_it = pred_expressions->iterator();
 431                 while (pred_expr_it->hasNext()) {
 432                         pred_expr * pred_expression = pred_expr_it->next();
 433                         uint64_t last_read, next_read;
 434                         bool equality;
 435
 436                         switch(pred_expression->token) {
 437                         case NOPREDICATE:
 438                                 predicate_correct = true;
 439                                 break;
 440                         case EQUALITY:
 441                                 FuncInst * to_be_compared;
 442                                 ModelAction * last_act;
 443
 444                                 to_be_compared = pred_expression->func_inst;
 445                                 last_act = to_be_compared->get_associated_act(marker);
 446
 447                                 last_read = last_act->get_reads_from_value();
 448                                 next_read = next_act->get_reads_from_value();
 449                                 equality = (last_read == next_read);
 450                                 if (equality != pred_expression->value)
 451                                         predicate_correct = false;
 452
 453                                 break;
 454                         case NULLITY:
 455                                 next_read = next_act->get_reads_from_value();
 456                                 // TODO: implement likely to be null
 457                                 equality = ( (void*) (next_read & 0xffffffff) == NULL);
 458                                 if (equality != pred_expression->value)
 459                                         predicate_correct = false;
 460                                 break;
 461                         default:
 462                                 predicate_correct = false;
 463                                 model_print("unkown predicate token\n");
 464                                 break;
 465                         }
 466                 }
 467
 468                 delete pred_expr_it;
 469
 470                 if (predicate_correct) {
 471                         *curr_pred = branch;
 472                         branch_found = true;
 473                         break;
 474                 }
 475         }
 476
 477         return branch_found;
 478 }
 479
 480 /* Infer predicate expressions, which are generated in FuncNode::generate_predicates */
 481 void FuncNode::infer_predicates(FuncInst * next_inst, ModelAction * next_act,
 482                                                                                                                                 SnapVector<struct half_pred_expr *> * half_pred_expressions)
 483 {
 484         void * loc = next_act->get_location();
 485
 486         if (next_inst->is_read()) {
 487                 /* read + rmw */
 488                 if ( loc_act_map.contains(loc) ) {
 489                         ModelAction * last_act = loc_act_map.get(loc);
 490                         FuncInst * last_inst = get_inst(last_act);
 491                         struct half_pred_expr * expression = new half_pred_expr(EQUALITY, last_inst);
 492                         half_pred_expressions->push_back(expression);
 493                 } else if ( next_inst->is_single_location() ) {
 494                         loc_set_t * loc_may_equal = loc_may_equal_map->get(loc);
 495
 496                         if (loc_may_equal != NULL) {
 497                                 loc_set_iter * loc_it = loc_may_equal->iterator();
 498                                 while (loc_it->hasNext()) {
 499                                         void * neighbor = loc_it->next();
 500                                         if (loc_act_map.contains(neighbor)) {
 501                                                 ModelAction * last_act = loc_act_map.get(neighbor);
 502                                                 FuncInst * last_inst = get_inst(last_act);
 503
 504                                                 struct half_pred_expr * expression = new half_pred_expr(EQUALITY, last_inst);
 505                                                 half_pred_expressions->push_back(expression);
 506                                         }
 507                                 }
 508
 509                                 delete loc_it;
 510                         }
 511                 } else {
 512                         // next_inst is not single location
 513                         uint64_t read_val = next_act->get_reads_from_value();
 514
 515                         // only infer NULLITY predicate when it is actually NULL.
 516                         if ( (void*)read_val == NULL) {
 517                                 struct half_pred_expr * expression = new half_pred_expr(NULLITY, NULL);
 518                                 half_pred_expressions->push_back(expression);
 519                         }
 520                 }
 521         } else {
 522                 /* Pure writes */
 523                 // TODO: do anything here?
 524         }
 525 }
 526
 527 /* Able to generate complex predicates when there are multiple predciate expressions */
 528 void FuncNode::generate_predicates(Predicate * curr_pred, FuncInst * next_inst,
 529                                                                                                                                          SnapVector<struct half_pred_expr *> * half_pred_expressions)
 530 {
 531         if (half_pred_expressions->size() == 0) {
 532                 Predicate * new_pred = new Predicate(next_inst);
 533                 curr_pred->add_child(new_pred);
 534                 new_pred->set_parent(curr_pred);
 535
 536                 /* Maintain predicate leaves */
 537                 predicate_leaves.add(new_pred);
 538                 predicate_leaves.remove(curr_pred);
 539
 540                 /* entry predicates and predicates containing pure write actions
 541                  * have no predicate expressions */
 542                 if ( curr_pred->is_entry_predicate() )
 543                         new_pred->add_predicate_expr(NOPREDICATE, NULL, true);
 544                 else if (next_inst->is_write()) {
 545                         /* next_inst->is_write() <==> pure writes */
 546                         new_pred->add_predicate_expr(NOPREDICATE, NULL, true);
 547                 }
 548
 549                 return;
 550         }
 551
 552         SnapVector<Predicate *> predicates;
 553
 554         struct half_pred_expr * half_expr = (*half_pred_expressions)[0];
 555         predicates.push_back(new Predicate(next_inst));
 556         predicates.push_back(new Predicate(next_inst));
 557
 558         predicates[0]->add_predicate_expr(half_expr->token, half_expr->func_inst, true);
 559         predicates[1]->add_predicate_expr(half_expr->token, half_expr->func_inst, false);
 560
 561         for (uint i = 1;i < half_pred_expressions->size();i++) {
 562                 half_expr = (*half_pred_expressions)[i];
 563
 564                 uint old_size = predicates.size();
 565                 for (uint j = 0;j < old_size;j++) {
 566                         Predicate * pred = predicates[j];
 567                         Predicate * new_pred = new Predicate(next_inst);
 568                         new_pred->copy_predicate_expr(pred);
 569
 570                         pred->add_predicate_expr(half_expr->token, half_expr->func_inst, true);
 571                         new_pred->add_predicate_expr(half_expr->token, half_expr->func_inst, false);
 572
 573                         predicates.push_back(new_pred);
 574                 }
 575         }
 576
 577         for (uint i = 0;i < predicates.size();i++) {
 578                 Predicate * pred= predicates[i];
 579                 curr_pred->add_child(pred);
 580                 pred->set_parent(curr_pred);
 581
 582                 /* Add new predicate leaves */
 583                 predicate_leaves.add(pred);
 584         }
 585
 586         /* Remove predicate node that has children */
 587         predicate_leaves.remove(curr_pred);
 588
 589         /* Free memories allocated by infer_predicate */
 590         for (uint i = 0;i < half_pred_expressions->size();i++) {
 591                 struct half_pred_expr * tmp = (*half_pred_expressions)[i];
 592                 snapshot_free(tmp);
 593         }
 594 }
 595
 596 /* Amend predicates that contain no predicate expressions. Currenlty only amend with NULLITY predicates */
 597 bool FuncNode::amend_predicate_expr(Predicate * curr_pred, FuncInst * next_inst, ModelAction * next_act)
 598 {
 599         ModelVector<Predicate *> * children = curr_pred->get_children();
 600
 601         Predicate * unset_pred = NULL;
 602         for (uint i = 0;i < children->size();i++) {
 603                 Predicate * child = (*children)[i];
 604                 if (child->get_func_inst() == next_inst) {
 605                         unset_pred = child;
 606                         break;
 607                 }
 608         }
 609
 610         uint64_t read_val = next_act->get_reads_from_value();
 611
 612         // only generate NULLITY predicate when it is actually NULL.
 613         if ( !next_inst->is_single_location() && (void*)read_val == NULL ) {
 614                 Predicate * new_pred = new Predicate(next_inst);
 615
 616                 curr_pred->add_child(new_pred);
 617                 new_pred->set_parent(curr_pred);
 618
 619                 unset_pred->add_predicate_expr(NULLITY, NULL, false);
 620                 new_pred->add_predicate_expr(NULLITY, NULL, true);
 621
 622                 return true;
 623         }
 624
 625         return false;
 626 }
 627
 628 void FuncNode::add_to_val_loc_map(uint64_t val, void * loc)
 629 {
 630         loc_set_t * locations = val_loc_map->get(val);
 631
 632         if (locations == NULL) {
 633                 locations = new loc_set_t();
 634                 val_loc_map->put(val, locations);
 635         }
 636
 637         update_loc_may_equal_map(loc, locations);
 638         locations->add(loc);
 639         // values_may_read_from->add(val);
 640 }
 641
 642 void FuncNode::add_to_val_loc_map(value_set_t * values, void * loc)
 643 {
 644         if (values == NULL)
 645                 return;
 646
 647         value_set_iter * it = values->iterator();
 648         while (it->hasNext()) {
 649                 uint64_t val = it->next();
 650                 add_to_val_loc_map(val, loc);
 651         }
 652
 653         delete it;
 654 }
 655
 656 void FuncNode::update_loc_may_equal_map(void * new_loc, loc_set_t * old_locations)
 657 {
 658         if ( old_locations->contains(new_loc) )
 659                 return;
 660
 661         loc_set_t * neighbors = loc_may_equal_map->get(new_loc);
 662
 663         if (neighbors == NULL) {
 664                 neighbors = new loc_set_t();
 665                 loc_may_equal_map->put(new_loc, neighbors);
 666         }
 667
 668         loc_set_iter * loc_it = old_locations->iterator();
 669         while (loc_it->hasNext()) {
 670                 // new_loc: { old_locations, ... }
 671                 void * member = loc_it->next();
 672                 neighbors->add(member);
 673
 674                 // for each i in old_locations, i : { new_loc, ... }
 675                 loc_set_t * _neighbors = loc_may_equal_map->get(member);
 676                 if (_neighbors == NULL) {
 677                         _neighbors = new loc_set_t();
 678                         loc_may_equal_map->put(member, _neighbors);
 679                 }
 680                 _neighbors->add(new_loc);
 681         }
 682
 683         delete loc_it;
 684 }
 685
 686 /* Every time a thread enters a function, set its position to the predicate tree entry */
 687 void FuncNode::init_predicate_tree_position(thread_id_t tid)
 688 {
 689         int thread_id = id_to_int(tid);
 690         if (predicate_tree_position.size() <= (uint) thread_id)
 691                 predicate_tree_position.resize(thread_id + 1);
 692
 693         predicate_tree_position[thread_id] = predicate_tree_entry;
 694 }
 695
 696 void FuncNode::set_predicate_tree_position(thread_id_t tid, Predicate * pred)
 697 {
 698         int thread_id = id_to_int(tid);
 699         predicate_tree_position[thread_id] = pred;
 700 }
 701
 702 /* @return The position of a thread in a predicate tree */
 703 Predicate * FuncNode::get_predicate_tree_position(thread_id_t tid)
 704 {
 705         int thread_id = id_to_int(tid);
 706         return predicate_tree_position[thread_id];
 707 }
 708
 709 /* Make sure elements of thrd_inst_act_map are initialized properly when threads enter functions */
 710 void FuncNode::init_inst_act_map(thread_id_t tid)
 711 {
 712         int thread_id = id_to_int(tid);
 713         SnapVector<inst_act_map_t *> * thrd_inst_act_map = history->getThrdInstActMap(func_id);
 714         uint old_size = thrd_inst_act_map->size();
 715
 716         if (thrd_inst_act_map->size() <= (uint) thread_id) {
 717                 uint new_size = thread_id + 1;
 718                 thrd_inst_act_map->resize(new_size);
 719
 720                 for (uint i = old_size;i < new_size;i++)
 721                         (*thrd_inst_act_map)[i] = new inst_act_map_t(128);
 722         }
 723 }
 724
 725 /* Reset elements of thrd_inst_act_map when threads exit functions */
 726 void FuncNode::reset_inst_act_map(thread_id_t tid)
 727 {
 728         int thread_id = id_to_int(tid);
 729         SnapVector<inst_act_map_t *> * thrd_inst_act_map = history->getThrdInstActMap(func_id);
 730
 731         inst_act_map_t * map = (*thrd_inst_act_map)[thread_id];
 732         map->reset();
 733 }
 734
 735 void FuncNode::update_inst_act_map(thread_id_t tid, ModelAction * read_act)
 736 {
 737         int thread_id = id_to_int(tid);
 738         SnapVector<inst_act_map_t *> * thrd_inst_act_map = history->getThrdInstActMap(func_id);
 739
 740         inst_act_map_t * map = (*thrd_inst_act_map)[thread_id];
 741         FuncInst * read_inst = get_inst(read_act);
 742         map->put(read_inst, read_act);
 743 }
 744
 745 inst_act_map_t * FuncNode::get_inst_act_map(thread_id_t tid)
 746 {
 747         int thread_id = id_to_int(tid);
 748         SnapVector<inst_act_map_t *> * thrd_inst_act_map = history->getThrdInstActMap(func_id);
 749
 750         return (*thrd_inst_act_map)[thread_id];
 751 }
 752
 753 /* Add FuncNodes that this node may follow */
 754 void FuncNode::add_out_edge(FuncNode * other)
 755 {
 756         if ( !edge_table.contains(other) ) {
 757                 edge_table.put(other, OUT_EDGE);
 758                 out_edges.push_back(other);
 759                 return;
 760         }
 761
 762         edge_type_t edge = edge_table.get(other);
 763         if (edge == IN_EDGE) {
 764                 edge_table.put(other, BI_EDGE);
 765                 out_edges.push_back(other);
 766         }
 767 }
 768
 769 /* Compute the distance between this FuncNode and the target node.
 770  * Return -1 if the target node is unreachable or the actual distance
 771  * is greater than max_step.
 772  */
 773 int FuncNode::compute_distance(FuncNode * target, int max_step)
 774 {
 775         if (target == NULL)
 776                 return -1;
 777         else if (target == this)
 778                 return 0;
 779
 780         SnapList<FuncNode *> queue;
 781         HashTable<FuncNode *, int, uintptr_t, 0> distances(128);
 782
 783         queue.push_back(this);
 784         distances.put(this, 0);
 785
 786         while (!queue.empty()) {
 787                 FuncNode * curr = queue.front();
 788                 queue.pop_front();
 789                 int dist = distances.get(curr);
 790
 791                 if (max_step <= dist)
 792                         return -1;
 793
 794                 ModelList<FuncNode *> * outEdges = curr->get_out_edges();
 795                 mllnode<FuncNode *> * it;
 796                 for (it = outEdges->begin();it != NULL;it = it->getNext()) {
 797                         FuncNode * out_node = it->getVal();
 798
 799                         /* This node has not been visited before */
 800                         if ( !distances.contains(out_node) ) {
 801                                 if (out_node == target)
 802                                         return dist + 1;
 803
 804                                 queue.push_back(out_node);
 805                                 distances.put(out_node, dist + 1);
 806                         }
 807                 }
 808         }
 809
 810         /* Target node is unreachable */
 811         return -1;
 812 }
 813
 814 void FuncNode::add_failed_predicate(Predicate * pred)
 815 {
 816         failed_predicates.add(pred);
 817 }
 818
 819 /* Implement quick sort to sort leaves before assigning base scores */
 820 template<typename _Tp>
 821 static int partition(ModelVector<_Tp *> * arr, int low, int high)
 822 {
 823         unsigned int pivot = (*arr)[high] -> get_depth();
 824         int i = low - 1;
 825
 826         for (int j = low;j <= high - 1;j ++) {
 827                 if ( (*arr)[j] -> get_depth() < pivot ) {
 828                         i ++;
 829                         _Tp * tmp = (*arr)[i];
 830                         (*arr)[i] = (*arr)[j];
 831                         (*arr)[j] = tmp;
 832                 }
 833         }
 834
 835         _Tp * tmp = (*arr)[i + 1];
 836         (*arr)[i + 1] = (*arr)[high];
 837         (*arr)[high] = tmp;
 838
 839         return i + 1;
 840 }
 841
 842 /* Implement quick sort to sort leaves before assigning base scores */
 843 template<typename _Tp>
 844 static void quickSort(ModelVector<_Tp *> * arr, int low, int high)
 845 {
 846         if (low < high) {
 847                 int pi = partition(arr, low, high);
 848
 849                 quickSort(arr, low, pi - 1);
 850                 quickSort(arr, pi + 1, high);
 851         }
 852 }
 853
 854 void FuncNode::assign_initial_weight()
 855 {
 856         PredSetIter * it = predicate_leaves.iterator();
 857         leaves_tmp_storage.clear();
 858
 859         while (it->hasNext()) {
 860                 Predicate * pred = it->next();
 861                 double weight = 100.0 / sqrt(pred->get_expl_count() + pred->get_fail_count() + 1);
 862                 pred->set_weight(weight);
 863                 leaves_tmp_storage.push_back(pred);
 864         }
 865         delete it;
 866
 867         quickSort(&leaves_tmp_storage, 0, leaves_tmp_storage.size() - 1);
 868
 869         // assign scores for internal nodes;
 870         while ( !leaves_tmp_storage.empty() ) {
 871                 Predicate * leaf = leaves_tmp_storage.back();
 872                 leaves_tmp_storage.pop_back();
 873
 874                 Predicate * curr = leaf->get_parent();
 875                 while (curr != NULL) {
 876                         if (curr->get_weight() != 0) {
 877                                 // Has been exlpored
 878                                 break;
 879                         }
 880
 881                         ModelVector<Predicate *> * children = curr->get_children();
 882                         double weight_sum = 0;
 883                         bool has_unassigned_node = false;
 884
 885                         for (uint i = 0;i < children->size();i++) {
 886                                 Predicate * child = (*children)[i];
 887
 888                                 // If a child has unassigned weight
 889                                 double weight = child->get_weight();
 890                                 if (weight == 0) {
 891                                         has_unassigned_node = true;
 892                                         break;
 893                                 } else
 894                                         weight_sum += weight;
 895                         }
 896
 897                         if (!has_unassigned_node) {
 898                                 double average_weight = (double) weight_sum / (double) children->size();
 899                                 double weight = average_weight * pow(0.9, curr->get_depth());
 900                                 curr->set_weight(weight);
 901                         } else
 902                                 break;
 903
 904                         curr = curr->get_parent();
 905                 }
 906         }
 907 }
 908
 909 void FuncNode::update_predicate_tree_weight()
 910 {
 911         if (marker == 2) {
 912                 // Predicate tree is initially built
 913                 assign_initial_weight();
 914                 return;
 915         }
 916
 917         weight_debug_vec.clear();
 918
 919         PredSetIter * it = failed_predicates.iterator();
 920         while (it->hasNext()) {
 921                 Predicate * pred = it->next();
 922                 leaves_tmp_storage.push_back(pred);
 923         }
 924         delete it;
 925         failed_predicates.reset();
 926
 927         quickSort(&leaves_tmp_storage, 0, leaves_tmp_storage.size() - 1);
 928         for (uint i = 0;i < leaves_tmp_storage.size();i++) {
 929                 Predicate * pred = leaves_tmp_storage[i];
 930                 double weight = 100.0 / sqrt(pred->get_expl_count() + pred->get_fail_count() + 1);
 931                 pred->set_weight(weight);
 932         }
 933
 934         // Update weights in internal nodes
 935         while ( !leaves_tmp_storage.empty() ) {
 936                 Predicate * leaf = leaves_tmp_storage.back();
 937                 leaves_tmp_storage.pop_back();
 938
 939                 Predicate * curr = leaf->get_parent();
 940                 while (curr != NULL) {
 941                         ModelVector<Predicate *> * children = curr->get_children();
 942                         double weight_sum = 0;
 943                         bool has_unassigned_node = false;
 944
 945                         for (uint i = 0;i < children->size();i++) {
 946                                 Predicate * child = (*children)[i];
 947
 948                                 double weight = child->get_weight();
 949                                 if (weight != 0)
 950                                         weight_sum += weight;
 951                                 else if ( predicate_leaves.contains(child) ) {
 952                                         // If this child is a leaf
 953                                         double weight = 100.0 / sqrt(child->get_expl_count() + 1);
 954                                         child->set_weight(weight);
 955                                         weight_sum += weight;
 956                                 } else {
 957                                         has_unassigned_node = true;
 958                                         weight_debug_vec.push_back(child);      // For debugging purpose
 959                                         break;
 960                                 }
 961                         }
 962
 963                         if (!has_unassigned_node) {
 964                                 double average_weight = (double) weight_sum / (double) children->size();
 965                                 double weight = average_weight * pow(0.9, curr->get_depth());
 966                                 curr->set_weight(weight);
 967                         } else
 968                                 break;
 969
 970                         curr = curr->get_parent();
 971                 }
 972         }
 973
 974         for (uint i = 0;i < weight_debug_vec.size();i++) {
 975                 Predicate * tmp = weight_debug_vec[i];
 976                 ASSERT( tmp->get_weight() != 0 );
 977         }
 978 }
 979
 980 void FuncNode::print_predicate_tree()
 981 {
 982         model_print("digraph function_%s {\n", func_name);
 983         predicate_tree_entry->print_pred_subtree();
 984         predicate_tree_exit->print_predicate();
 985         model_print("}\n");     // end of graph
 986 }