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
  10 FuncNode::FuncNode(ModelHistory * history) :
  11         history(history),
  12         exit_count(0),
  13         marker(1),
  14         func_inst_map(),
  15         inst_list(),
  16         entry_insts(),
  17         predicate_tree_position(),
  18         edge_table(32),
  19         out_edges()
  20 {
  21         predicate_tree_entry = new Predicate(NULL, true);
  22         predicate_tree_entry->add_predicate_expr(NOPREDICATE, NULL, true);
  23         predicate_tree_exit = new Predicate(NULL, false, true);
  24
  25         // Memories that are reclaimed after each execution
  26         action_list_buffer = new SnapList<action_list_t *>();
  27         read_locations = new loc_set_t();
  28         write_locations = new loc_set_t();
  29         val_loc_map = new HashTable<uint64_t, loc_set_t *, uint64_t, 0>();
  30         loc_may_equal_map = new HashTable<void *, loc_set_t *, uintptr_t, 0>();
  31
  32         //values_may_read_from = new value_set_t();
  33 }
  34
  35 /* Reallocate snapshotted memories when new executions start */
  36 void FuncNode::set_new_exec_flag()
  37 {
  38         action_list_buffer = new SnapList<action_list_t *>();
  39         read_locations = new loc_set_t();
  40         write_locations = new loc_set_t();
  41         val_loc_map = new HashTable<uint64_t, loc_set_t *, uint64_t, 0>();
  42         loc_may_equal_map = new HashTable<void *, loc_set_t *, uintptr_t, 0>();
  43
  44         //values_may_read_from = new value_set_t();
  45 }
  46
  47 /* Check whether FuncInst with the same type, position, and location
  48  * as act has been added to func_inst_map or not. If not, add it.
  49  *
  50  * Note: currently, actions with the same position are filtered out by process_action,
  51  * so the collision list of FuncInst is not used. May remove it later.
  52  */
  53 void FuncNode::add_inst(ModelAction *act)
  54 {
  55         ASSERT(act);
  56         const char * position = act->get_position();
  57
  58         /* THREAD* actions, ATOMIC_LOCK, ATOMIC_TRYLOCK, and ATOMIC_UNLOCK
  59          * actions are not tagged with their source line numbers
  60          */
  61         if (position == NULL)
  62                 return;
  63
  64         if ( func_inst_map.contains(position) ) {
  65                 FuncInst * inst = func_inst_map.get(position);
  66
  67                 ASSERT(inst->get_type() == act->get_type());
  68                 int curr_execution_number = model->get_execution_number();
  69
  70                 /* Reset locations when new executions start */
  71                 if (inst->get_execution_number() != curr_execution_number) {
  72                         inst->set_location(act->get_location());
  73                         inst->set_execution_number(curr_execution_number);
  74                 }
  75
  76                 if (inst->get_location() != act->get_location())
  77                         inst->not_single_location();
  78
  79                 return;
  80         }
  81
  82         FuncInst * func_inst = new FuncInst(act, this);
  83
  84         func_inst_map.put(position, func_inst);
  85         inst_list.push_back(func_inst);
  86 }
  87
  88 /* Get the FuncInst with the same type, position, and location
  89  * as act
  90  *
  91  * @return FuncInst with the same type, position, and location as act */
  92 FuncInst * FuncNode::get_inst(ModelAction *act)
  93 {
  94         ASSERT(act);
  95         const char * position = act->get_position();
  96
  97         /* THREAD* actions, ATOMIC_LOCK, ATOMIC_TRYLOCK, and ATOMIC_UNLOCK
  98          * actions are not tagged with their source line numbers
  99          */
 100         if (position == NULL)
 101                 return NULL;
 102
 103         FuncInst * inst = func_inst_map.get(position);
 104         if (inst == NULL)
 105                 return NULL;
 106
 107         action_type inst_type = inst->get_type();
 108         action_type act_type = act->get_type();
 109
 110         // else if branch: an RMWRCAS action is converted to a RMW or READ action
 111         if (inst_type == act_type)
 112                 return inst;
 113         else if (inst_type == ATOMIC_RMWRCAS &&
 114                         (act_type == ATOMIC_RMW || act_type == ATOMIC_READ))
 115                 return inst;
 116
 117         return NULL;
 118 }
 119
 120
 121 void FuncNode::add_entry_inst(FuncInst * inst)
 122 {
 123         if (inst == NULL)
 124                 return;
 125
 126         mllnode<FuncInst *> * it;
 127         for (it = entry_insts.begin(); it != NULL; it = it->getNext()) {
 128                 if (inst == it->getVal())
 129                         return;
 130         }
 131
 132         entry_insts.push_back(inst);
 133 }
 134
 135 /**
 136  * @brief Convert ModelAdtion list to FuncInst list
 137  * @param act_list A list of ModelActions
 138  */
 139 void FuncNode::update_tree(action_list_t * act_list)
 140 {
 141         if (act_list == NULL || act_list->size() == 0)
 142                 return;
 143
 144         HashTable<void *, value_set_t *, uintptr_t, 0> * write_history = history->getWriteHistory();
 145
 146         /* build inst_list from act_list for later processing */
 147         func_inst_list_t inst_list;
 148         action_list_t rw_act_list;
 149
 150         for (sllnode<ModelAction *> * it = act_list->begin(); it != NULL; it = it->getNext()) {
 151                 ModelAction * act = it->getVal();
 152                 FuncInst * func_inst = get_inst(act);
 153                 void * loc = act->get_location();
 154
 155                 if (func_inst == NULL)
 156                         continue;
 157
 158                 inst_list.push_back(func_inst);
 159                 bool act_added = false;
 160
 161                 if (act->is_write()) {
 162                         rw_act_list.push_back(act);
 163                         act_added = true;
 164                         if (!write_locations->contains(loc)) {
 165                                 write_locations->add(loc);
 166                                 history->update_loc_wr_func_nodes_map(loc, this);
 167                         }
 168                 }
 169
 170                 if (act->is_read()) {
 171                         if (!act_added)
 172                                 rw_act_list.push_back(act);
 173
 174                         /* If func_inst may only read_from a single location, then:
 175                          *
 176                          * The first time an action reads from some location,
 177                          * import all the values that have been written to this
 178                          * location from ModelHistory and notify ModelHistory
 179                          * that this FuncNode may read from this location.
 180                          */
 181                         if (!read_locations->contains(loc) && func_inst->is_single_location()) {
 182                                 read_locations->add(loc);
 183                                 value_set_t * write_values = write_history->get(loc);
 184                                 add_to_val_loc_map(write_values, loc);
 185                                 history->update_loc_rd_func_nodes_map(loc, this);
 186                         }
 187                 }
 188         }
 189
 190 //      model_print("function %s\n", func_name);
 191 //      print_val_loc_map();
 192
 193         update_inst_tree(&inst_list);
 194         update_predicate_tree(&rw_act_list);
 195
 196 //      print_predicate_tree();
 197 }
 198
 199 /**
 200  * @brief Link FuncInsts in inst_list  - add one FuncInst to another's predecessors and successors
 201  * @param inst_list A list of FuncInsts
 202  */
 203 void FuncNode::update_inst_tree(func_inst_list_t * inst_list)
 204 {
 205         if (inst_list == NULL)
 206                 return;
 207         else if (inst_list->size() == 0)
 208                 return;
 209
 210         /* start linking */
 211         sllnode<FuncInst *>* it = inst_list->begin();
 212         sllnode<FuncInst *>* prev;
 213
 214         /* add the first instruction to the list of entry insts */
 215         FuncInst * entry_inst = it->getVal();
 216         add_entry_inst(entry_inst);
 217
 218         it = it->getNext();
 219         while (it != NULL) {
 220                 prev = it->getPrev();
 221
 222                 FuncInst * prev_inst = prev->getVal();
 223                 FuncInst * curr_inst = it->getVal();
 224
 225                 prev_inst->add_succ(curr_inst);
 226                 curr_inst->add_pred(prev_inst);
 227
 228                 it = it->getNext();
 229         }
 230 }
 231
 232 void FuncNode::update_predicate_tree(action_list_t * act_list)
 233 {
 234         if (act_list == NULL || act_list->size() == 0)
 235                 return;
 236
 237         incr_marker();
 238
 239         /* Map a FuncInst to the its predicate */
 240         HashTable<FuncInst *, Predicate *, uintptr_t, 0> inst_pred_map(128);
 241
 242         // Number FuncInsts to detect loops
 243         HashTable<FuncInst *, uint32_t, uintptr_t, 0> inst_id_map(128);
 244         uint32_t inst_counter = 0;
 245
 246         /* Only need to store the locations of read actions */
 247         HashTable<void *, ModelAction *, uintptr_t, 0> loc_act_map(128);
 248
 249         sllnode<ModelAction *> *it = act_list->begin();
 250         Predicate * curr_pred = predicate_tree_entry;
 251         while (it != NULL) {
 252                 ModelAction * next_act = it->getVal();
 253                 FuncInst * next_inst = get_inst(next_act);
 254                 next_inst->set_associated_act(next_act, marker);
 255
 256                 SnapVector<Predicate *> unset_predicates = SnapVector<Predicate *>();
 257                 bool branch_found = follow_branch(&curr_pred, next_inst, next_act, &unset_predicates);
 258
 259                 // A branch with unset predicate expression is detected
 260                 if (!branch_found && unset_predicates.size() != 0) {
 261                         ASSERT(unset_predicates.size() == 1);
 262                         Predicate * one_branch = unset_predicates[0];
 263
 264                         bool amended = amend_predicate_expr(&curr_pred, next_inst, next_act);
 265                         if (amended)
 266                                 continue;
 267                         else {
 268                                 curr_pred = one_branch;
 269                                 branch_found = true;
 270                         }
 271                 }
 272
 273                 // Detect loops
 274                 if (!branch_found && inst_id_map.contains(next_inst)) {
 275                         FuncInst * curr_inst = curr_pred->get_func_inst();
 276                         uint32_t curr_id = inst_id_map.get(curr_inst);
 277                         uint32_t next_id = inst_id_map.get(next_inst);
 278
 279                         if (curr_id >= next_id) {
 280                                 Predicate * old_pred = inst_pred_map.get(next_inst);
 281                                 Predicate * back_pred = old_pred->get_parent();
 282
 283                                 curr_pred->add_backedge(back_pred);
 284                                 curr_pred = back_pred;
 285                                 continue;
 286                         }
 287                 }
 288
 289                 // Generate new branches
 290                 if (!branch_found) {
 291                         SnapVector<struct half_pred_expr *> half_pred_expressions;
 292                         infer_predicates(next_inst, next_act, &loc_act_map, &half_pred_expressions);
 293                         generate_predicates(&curr_pred, next_inst, &half_pred_expressions);
 294                         continue;
 295                 }
 296
 297                 if (next_act->is_write())
 298                         curr_pred->set_write(true);
 299
 300                 if (next_act->is_read()) {
 301                         loc_act_map.put(next_act->get_location(), next_act);
 302                 }
 303
 304                 inst_pred_map.put(next_inst, curr_pred);
 305                 if (!inst_id_map.contains(next_inst))
 306                         inst_id_map.put(next_inst, inst_counter++);
 307
 308                 it = it->getNext();
 309                 curr_pred->incr_expl_count();
 310         }
 311
 312         curr_pred->set_exit(predicate_tree_exit);
 313 }
 314
 315 /* Given curr_pred and next_inst, find the branch following curr_pred that
 316  * contains next_inst and the correct predicate.
 317  * @return true if branch found, false otherwise.
 318  */
 319 bool FuncNode::follow_branch(Predicate ** curr_pred, FuncInst * next_inst,
 320         ModelAction * next_act, SnapVector<Predicate *> * unset_predicates)
 321 {
 322         /* Check if a branch with func_inst and corresponding predicate exists */
 323         bool branch_found = false;
 324         ModelVector<Predicate *> * branches = (*curr_pred)->get_children();
 325         for (uint i = 0; i < branches->size(); i++) {
 326                 Predicate * branch = (*branches)[i];
 327                 if (branch->get_func_inst() != next_inst)
 328                         continue;
 329
 330                 /* Check against predicate expressions */
 331                 bool predicate_correct = true;
 332                 PredExprSet * pred_expressions = branch->get_pred_expressions();
 333                 PredExprSetIter * pred_expr_it = pred_expressions->iterator();
 334
 335                 /* Only read and rmw actions my have unset predicate expressions */
 336                 if (pred_expressions->getSize() == 0) {
 337                         predicate_correct = false;
 338                         unset_predicates->push_back(branch);
 339                 }
 340
 341                 while (pred_expr_it->hasNext()) {
 342                         pred_expr * pred_expression = pred_expr_it->next();
 343                         uint64_t last_read, next_read;
 344                         bool equality;
 345
 346                         switch(pred_expression->token) {
 347                                 case NOPREDICATE:
 348                                         predicate_correct = true;
 349                                         break;
 350                                 case EQUALITY:
 351                                         FuncInst * to_be_compared;
 352                                         ModelAction * last_act;
 353
 354                                         to_be_compared = pred_expression->func_inst;
 355                                         last_act = to_be_compared->get_associated_act(marker);
 356
 357                                         last_read = last_act->get_reads_from_value();
 358                                         next_read = next_act->get_reads_from_value();
 359                                         equality = (last_read == next_read);
 360                                         if (equality != pred_expression->value)
 361                                                 predicate_correct = false;
 362
 363                                         break;
 364                                 case NULLITY:
 365                                         next_read = next_act->get_reads_from_value();
 366                                         equality = ((void*)next_read == NULL);
 367                                         if (equality != pred_expression->value)
 368                                                 predicate_correct = false;
 369                                         break;
 370                                 default:
 371                                         predicate_correct = false;
 372                                         model_print("unkown predicate token\n");
 373                                         break;
 374                         }
 375                 }
 376
 377                 if (predicate_correct) {
 378                         *curr_pred = branch;
 379                         branch_found = true;
 380                         break;
 381                 }
 382         }
 383
 384         return branch_found;
 385 }
 386
 387 /* Infer predicate expressions, which are generated in FuncNode::generate_predicates */
 388 void FuncNode::infer_predicates(FuncInst * next_inst, ModelAction * next_act,
 389         HashTable<void *, ModelAction *, uintptr_t, 0> * loc_act_map,
 390         SnapVector<struct half_pred_expr *> * half_pred_expressions)
 391 {
 392         void * loc = next_act->get_location();
 393
 394         if (next_inst->is_read()) {
 395                 /* read + rmw */
 396                 if ( loc_act_map->contains(loc) ) {
 397                         ModelAction * last_act = loc_act_map->get(loc);
 398                         FuncInst * last_inst = get_inst(last_act);
 399                         struct half_pred_expr * expression = new half_pred_expr(EQUALITY, last_inst);
 400                         half_pred_expressions->push_back(expression);
 401                 } else if ( next_inst->is_single_location() ){
 402                         loc_set_t * loc_may_equal = loc_may_equal_map->get(loc);
 403
 404                         if (loc_may_equal != NULL) {
 405                                 loc_set_iter * loc_it = loc_may_equal->iterator();
 406                                 while (loc_it->hasNext()) {
 407                                         void * neighbor = loc_it->next();
 408                                         if (loc_act_map->contains(neighbor)) {
 409                                                 ModelAction * last_act = loc_act_map->get(neighbor);
 410                                                 FuncInst * last_inst = get_inst(last_act);
 411
 412                                                 struct half_pred_expr * expression = new half_pred_expr(EQUALITY, last_inst);
 413                                                 half_pred_expressions->push_back(expression);
 414                                         }
 415                                 }
 416                         }
 417                 } else {
 418                         // next_inst is not single location
 419                         uint64_t read_val = next_act->get_reads_from_value();
 420
 421                         // only infer NULLITY predicate when it is actually NULL.
 422                         if ( (void*)read_val == NULL) {
 423                                 struct half_pred_expr * expression = new half_pred_expr(NULLITY, NULL);
 424                                 half_pred_expressions->push_back(expression);
 425                         }
 426                 }
 427         } else {
 428                 /* Pure writes */
 429                 // TODO: do anything here?
 430         }
 431 }
 432
 433 /* Able to generate complex predicates when there are multiple predciate expressions */
 434 void FuncNode::generate_predicates(Predicate ** curr_pred, FuncInst * next_inst,
 435         SnapVector<struct half_pred_expr *> * half_pred_expressions)
 436 {
 437         if (half_pred_expressions->size() == 0) {
 438                 Predicate * new_pred = new Predicate(next_inst);
 439                 (*curr_pred)->add_child(new_pred);
 440                 new_pred->set_parent(*curr_pred);
 441
 442                 /* entry predicates and predicates containing pure write actions
 443                  * have no predicate expressions */
 444                 if ( (*curr_pred)->is_entry_predicate() )
 445                         new_pred->add_predicate_expr(NOPREDICATE, NULL, true);
 446                 else if (next_inst->is_write()) {
 447                         /* next_inst->is_write() <==> pure writes */
 448                         new_pred->add_predicate_expr(NOPREDICATE, NULL, true);
 449                 }
 450
 451                 return;
 452         }
 453
 454         SnapVector<Predicate *> predicates;
 455
 456         struct half_pred_expr * half_expr = (*half_pred_expressions)[0];
 457         predicates.push_back(new Predicate(next_inst));
 458         predicates.push_back(new Predicate(next_inst));
 459
 460         predicates[0]->add_predicate_expr(half_expr->token, half_expr->func_inst, true);
 461         predicates[1]->add_predicate_expr(half_expr->token, half_expr->func_inst, false);
 462
 463         for (uint i = 1; i < half_pred_expressions->size(); i++) {
 464                 half_expr = (*half_pred_expressions)[i];
 465
 466                 uint old_size = predicates.size();
 467                 for (uint j = 0; j < old_size; j++) {
 468                         Predicate * pred = predicates[j];
 469                         Predicate * new_pred = new Predicate(next_inst);
 470                         new_pred->copy_predicate_expr(pred);
 471
 472                         pred->add_predicate_expr(half_expr->token, half_expr->func_inst, true);
 473                         new_pred->add_predicate_expr(half_expr->token, half_expr->func_inst, false);
 474
 475                         predicates.push_back(new_pred);
 476                 }
 477         }
 478
 479         for (uint i = 0; i < predicates.size(); i++) {
 480                 Predicate * pred= predicates[i];
 481                 (*curr_pred)->add_child(pred);
 482                 pred->set_parent(*curr_pred);
 483         }
 484
 485         /* Free memories allocated by infer_predicate */
 486         for (uint i = 0; i < half_pred_expressions->size(); i++) {
 487                 struct half_pred_expr * tmp = (*half_pred_expressions)[i];
 488                 snapshot_free(tmp);
 489         }
 490 }
 491
 492 /* Amend predicates that contain no predicate expressions. Currenlty only amend with NULLITY predicates */
 493 bool FuncNode::amend_predicate_expr(Predicate ** curr_pred, FuncInst * next_inst, ModelAction * next_act)
 494 {
 495         // there should only be only child
 496         Predicate * unset_pred = (*curr_pred)->get_children()->back();
 497         uint64_t read_val = next_act->get_reads_from_value();
 498
 499         // only generate NULLITY predicate when it is actually NULL.
 500         if ( !next_inst->is_single_location() && (void*)read_val == NULL ) {
 501                 Predicate * new_pred = new Predicate(next_inst);
 502
 503                 (*curr_pred)->add_child(new_pred);
 504                 new_pred->set_parent(*curr_pred);
 505
 506                 unset_pred->add_predicate_expr(NULLITY, NULL, false);
 507                 new_pred->add_predicate_expr(NULLITY, NULL, true);
 508
 509                 return true;
 510         }
 511
 512         return false;
 513 }
 514
 515 void FuncNode::add_to_val_loc_map(uint64_t val, void * loc)
 516 {
 517         loc_set_t * locations = val_loc_map->get(val);
 518
 519         if (locations == NULL) {
 520                 locations = new loc_set_t();
 521                 val_loc_map->put(val, locations);
 522         }
 523
 524         update_loc_may_equal_map(loc, locations);
 525         locations->add(loc);
 526         // values_may_read_from->add(val);
 527 }
 528
 529 void FuncNode::add_to_val_loc_map(value_set_t * values, void * loc)
 530 {
 531         if (values == NULL)
 532                 return;
 533
 534         value_set_iter * it = values->iterator();
 535         while (it->hasNext()) {
 536                 uint64_t val = it->next();
 537                 add_to_val_loc_map(val, loc);
 538         }
 539 }
 540
 541 void FuncNode::update_loc_may_equal_map(void * new_loc, loc_set_t * old_locations)
 542 {
 543         if ( old_locations->contains(new_loc) )
 544                 return;
 545
 546         loc_set_t * neighbors = loc_may_equal_map->get(new_loc);
 547
 548         if (neighbors == NULL) {
 549                 neighbors = new loc_set_t();
 550                 loc_may_equal_map->put(new_loc, neighbors);
 551         }
 552
 553         loc_set_iter * loc_it = old_locations->iterator();
 554         while (loc_it->hasNext()) {
 555                 // new_loc: { old_locations, ... }
 556                 void * member = loc_it->next();
 557                 neighbors->add(member);
 558
 559                 // for each i in old_locations, i : { new_loc, ... }
 560                 loc_set_t * _neighbors = loc_may_equal_map->get(member);
 561                 if (_neighbors == NULL) {
 562                         _neighbors = new loc_set_t();
 563                         loc_may_equal_map->put(member, _neighbors);
 564                 }
 565                 _neighbors->add(new_loc);
 566         }
 567 }
 568
 569 /* Every time a thread enters a function, set its position to the predicate tree entry */
 570 void FuncNode::init_predicate_tree_position(thread_id_t tid)
 571 {
 572         int thread_id = id_to_int(tid);
 573         if (predicate_tree_position.size() <= (uint) thread_id)
 574                 predicate_tree_position.resize(thread_id + 1);
 575
 576         predicate_tree_position[thread_id] = predicate_tree_entry;
 577 }
 578
 579 void FuncNode::set_predicate_tree_position(thread_id_t tid, Predicate * pred)
 580 {
 581         int thread_id = id_to_int(tid);
 582         predicate_tree_position[thread_id] = pred;
 583 }
 584
 585 /* @return The position of a thread in a predicate tree */
 586 Predicate * FuncNode::get_predicate_tree_position(thread_id_t tid)
 587 {
 588         int thread_id = id_to_int(tid);
 589         return predicate_tree_position[thread_id];
 590 }
 591
 592 /* Make sure elements of thrd_inst_act_map are initialized properly when threads enter functions */
 593 void FuncNode::init_inst_act_map(thread_id_t tid)
 594 {
 595         int thread_id = id_to_int(tid);
 596         SnapVector<inst_act_map_t *> * thrd_inst_act_map = history->getThrdInstActMap(func_id);
 597         uint old_size = thrd_inst_act_map->size();
 598
 599         if (thrd_inst_act_map->size() <= (uint) thread_id) {
 600                 uint new_size = thread_id + 1;
 601                 thrd_inst_act_map->resize(new_size);
 602
 603                 for (uint i = old_size; i < new_size; i++)
 604                         (*thrd_inst_act_map)[i] = new inst_act_map_t(128);
 605         }
 606 }
 607
 608 /* Reset elements of thrd_inst_act_map when threads exit functions */
 609 void FuncNode::reset_inst_act_map(thread_id_t tid)
 610 {
 611         int thread_id = id_to_int(tid);
 612         SnapVector<inst_act_map_t *> * thrd_inst_act_map = history->getThrdInstActMap(func_id);
 613
 614         inst_act_map_t * map = (*thrd_inst_act_map)[thread_id];
 615         map->reset();
 616 }
 617
 618 void FuncNode::update_inst_act_map(thread_id_t tid, ModelAction * read_act)
 619 {
 620         int thread_id = id_to_int(tid);
 621         SnapVector<inst_act_map_t *> * thrd_inst_act_map = history->getThrdInstActMap(func_id);
 622
 623         inst_act_map_t * map = (*thrd_inst_act_map)[thread_id];
 624         FuncInst * read_inst = get_inst(read_act);
 625         map->put(read_inst, read_act);
 626 }
 627
 628 inst_act_map_t * FuncNode::get_inst_act_map(thread_id_t tid)
 629 {
 630         int thread_id = id_to_int(tid);
 631         SnapVector<inst_act_map_t *> * thrd_inst_act_map = history->getThrdInstActMap(func_id);
 632
 633         return (*thrd_inst_act_map)[thread_id];
 634 }
 635
 636 /* Add FuncNodes that this node may follow */
 637 void FuncNode::add_out_edge(FuncNode * other)
 638 {
 639         if ( !edge_table.contains(other) ) {
 640                 edge_table.put(other, OUT_EDGE);
 641                 out_edges.push_back(other);
 642                 return;
 643         }
 644
 645         edge_type_t edge = edge_table.get(other);
 646         if (edge == IN_EDGE) {
 647                 edge_table.put(other, BI_EDGE);
 648                 out_edges.push_back(other);
 649         }
 650 }
 651
 652 /* Compute the distance between this FuncNode and the target node.
 653  * Return -1 if the target node is unreachable or the actual distance
 654  * is greater than max_step.
 655  */
 656 int FuncNode::compute_distance(FuncNode * target, int max_step)
 657 {
 658         if (target == NULL)
 659                 return -1;
 660         else if (target == this)
 661                 return 0;
 662
 663         SnapList<FuncNode *> queue;
 664         HashTable<FuncNode *, int, uintptr_t, 0> distances(128);
 665
 666         queue.push_back(this);
 667         distances.put(this, 0);
 668
 669         while (!queue.empty()) {
 670                 FuncNode * curr = queue.front();
 671                 queue.pop_front();
 672                 int dist = distances.get(curr);
 673
 674                 if (max_step <= dist)
 675                         return -1;
 676
 677                 ModelList<FuncNode *> * outEdges = curr->get_out_edges();
 678                 mllnode<FuncNode *> * it;
 679                 for (it = outEdges->begin(); it != NULL; it = it->getNext()) {
 680                         FuncNode * out_node = it->getVal();
 681
 682                         /* This node has not been visited before */
 683                         if ( !distances.contains(out_node) ) {
 684                                 if (out_node == target)
 685                                         return dist + 1;
 686
 687                                 queue.push_back(out_node);
 688                                 distances.put(out_node, dist + 1);
 689                         }
 690                 }
 691         }
 692
 693         /* Target node is unreachable */
 694         return -1;
 695 }
 696
 697 void FuncNode::print_predicate_tree()
 698 {
 699         model_print("digraph function_%s {\n", func_name);
 700         predicate_tree_entry->print_pred_subtree();
 701         predicate_tree_exit->print_predicate();
 702         model_print("}\n");     // end of graph
 703 }
 704
 705 void FuncNode::print_val_loc_map()
 706 {
 707 /*
 708         value_set_iter * val_it = values_may_read_from->iterator();
 709         while (val_it->hasNext()) {
 710                 uint64_t value = val_it->next();
 711                 model_print("val %llx: ", value);
 712
 713                 loc_set_t * locations = val_loc_map->get(value);
 714                 loc_set_iter * loc_it = locations->iterator();
 715                 while (loc_it->hasNext()) {
 716                         void * location = loc_it->next();
 717                         model_print("%p ", location);
 718                 }
 719                 model_print("\n");
 720         }
 721 */
 722 }