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