funcnode.cc

   1 #include "funcnode.h"
   2
   3 FuncNode::FuncNode(ModelHistory * history) :
   4         history(history),
   5         exit_count(0),
   6         func_inst_map(),
   7         inst_list(),
   8         entry_insts(),
   9         predicate_tree_position(),
  10         edge_table(32),
  11         out_edges()
  12 {
  13         predicate_tree_entry = new Predicate(NULL, true);
  14         predicate_tree_entry->add_predicate_expr(NOPREDICATE, NULL, true);
  15
  16         // memories that are reclaimed after each execution
  17         action_list_buffer = new SnapList<action_list_t *>();
  18         read_locations = new loc_set_t();
  19         val_loc_map = new HashTable<uint64_t, loc_set_t *, uint64_t, 0>();
  20         loc_may_equal_map = new HashTable<void *, loc_set_t *, uintptr_t, 0>();
  21         thrd_inst_act_map = new SnapVector<inst_act_map_t *>();
  22
  23         //values_may_read_from = new value_set_t();
  24 }
  25
  26 /* Reallocate snapshotted memories when new executions start */
  27 void FuncNode::set_new_exec_flag()
  28 {
  29         for (mllnode<FuncInst *> * it = inst_list.begin(); it != NULL; it = it->getNext()) {
  30                 FuncInst * inst = it->getVal();
  31                 inst->unset_location();
  32         }
  33
  34         action_list_buffer = new SnapList<action_list_t *>();
  35         read_locations = new loc_set_t();
  36         val_loc_map = new HashTable<uint64_t, loc_set_t *, uint64_t, 0>();
  37         loc_may_equal_map = new HashTable<void *, loc_set_t *, uintptr_t, 0>();
  38         thrd_inst_act_map = new SnapVector<inst_act_map_t *>();
  39
  40         //values_may_read_from = new value_set_t();
  41 }
  42
  43 /* Check whether FuncInst with the same type, position, and location
  44  * as act has been added to func_inst_map or not. If not, add it.
  45  *
  46  * Note: currently, actions with the same position are filtered out by process_action,
  47  * so the collision list of FuncInst is not used. May remove it later.
  48  */
  49 void FuncNode::add_inst(ModelAction *act)
  50 {
  51         ASSERT(act);
  52         const char * position = act->get_position();
  53
  54         /* THREAD* actions, ATOMIC_LOCK, ATOMIC_TRYLOCK, and ATOMIC_UNLOCK
  55          * actions are not tagged with their source line numbers
  56          */
  57         if (position == NULL)
  58                 return;
  59
  60         if ( func_inst_map.contains(position) ) {
  61                 FuncInst * inst = func_inst_map.get(position);
  62
  63                 ASSERT(inst->get_type() == act->get_type());
  64
  65                 // locations are set to NULL when new executions start
  66                 if (inst->get_location() == NULL)
  67                         inst->set_location(act->get_location());
  68
  69                 if (inst->get_location() != act->get_location())
  70                         inst->not_single_location();
  71
  72                 return;
  73         }
  74
  75         FuncInst * func_inst = new FuncInst(act, this);
  76
  77         func_inst_map.put(position, func_inst);
  78         inst_list.push_back(func_inst);
  79 }
  80
  81 /* Get the FuncInst with the same type, position, and location
  82  * as act
  83  *
  84  * @return FuncInst with the same type, position, and location as act */
  85 FuncInst * FuncNode::get_inst(ModelAction *act)
  86 {
  87         ASSERT(act);
  88         const char * position = act->get_position();
  89
  90         /* THREAD* actions, ATOMIC_LOCK, ATOMIC_TRYLOCK, and ATOMIC_UNLOCK
  91          * actions are not tagged with their source line numbers
  92          */
  93         if (position == NULL)
  94                 return NULL;
  95
  96         FuncInst * inst = func_inst_map.get(position);
  97         if (inst == NULL)
  98                 return NULL;
  99
 100         action_type inst_type = inst->get_type();
 101         action_type act_type = act->get_type();
 102
 103         // else if branch: an RMWRCAS action is converted to a RMW or READ action
 104         if (inst_type == act_type)
 105                 return inst;
 106         else if (inst_type == ATOMIC_RMWRCAS &&
 107                         (act_type == ATOMIC_RMW || act_type == ATOMIC_READ))
 108                 return inst;
 109
 110         return NULL;
 111 }
 112
 113
 114 void FuncNode::add_entry_inst(FuncInst * inst)
 115 {
 116         if (inst == NULL)
 117                 return;
 118
 119         mllnode<FuncInst *> * it;
 120         for (it = entry_insts.begin(); it != NULL; it = it->getNext()) {
 121                 if (inst == it->getVal())
 122                         return;
 123         }
 124
 125         entry_insts.push_back(inst);
 126 }
 127
 128 /**
 129  * @brief Convert ModelAdtion list to FuncInst list
 130  * @param act_list A list of ModelActions
 131  */
 132 void FuncNode::update_tree(action_list_t * act_list)
 133 {
 134         if (act_list == NULL || act_list->size() == 0)
 135                 return;
 136
 137         HashTable<void *, value_set_t *, uintptr_t, 4> * write_history = history->getWriteHistory();
 138
 139         /* build inst_list from act_list for later processing */
 140         func_inst_list_t inst_list;
 141         action_list_t rw_act_list;
 142
 143         for (sllnode<ModelAction *> * it = act_list->begin(); it != NULL; it = it->getNext()) {
 144                 ModelAction * act = it->getVal();
 145                 FuncInst * func_inst = get_inst(act);
 146
 147                 if (func_inst == NULL)
 148                         continue;
 149
 150                 inst_list.push_back(func_inst);
 151
 152                 /* NOTE: for rmw actions, func_inst and act may have different
 153                  * action types because of action type conversion in ModelExecution
 154                  * func_inst->is_write() <==> pure writes (excluding rmw) */
 155                 if (func_inst->is_write()) {
 156                         // model_print("write detected\n");
 157                         rw_act_list.push_back(act);
 158                 }
 159
 160                 /* func_inst->is_read() <==> read + rmw */
 161                 if (func_inst->is_read()) {
 162                         rw_act_list.push_back(act);
 163                         /* If func_inst may only read_from a single location, then:
 164                          *
 165                          * The first time an action reads from some location,
 166                          * import all the values that have been written to this
 167                          * location from ModelHistory and notify ModelHistory
 168                          * that this FuncNode may read from this location.
 169                          */
 170                         void * loc = act->get_location();
 171                         if (!read_locations->contains(loc) && func_inst->is_single_location()) {
 172                                 read_locations->add(loc);
 173                                 value_set_t * write_values = write_history->get(loc);
 174                                 add_to_val_loc_map(write_values, loc);
 175                                 history->add_to_loc_func_nodes_map(loc, this);
 176                         }
 177                 }
 178         }
 179
 180 //      model_print("function %s\n", func_name);
 181 //      print_val_loc_map();
 182
 183         update_inst_tree(&inst_list);
 184         update_predicate_tree(&rw_act_list);
 185
 186 //      print_predicate_tree();
 187 }
 188
 189 /**
 190  * @brief Link FuncInsts in inst_list  - add one FuncInst to another's predecessors and successors
 191  * @param inst_list A list of FuncInsts
 192  */
 193 void FuncNode::update_inst_tree(func_inst_list_t * inst_list)
 194 {
 195         if (inst_list == NULL)
 196                 return;
 197         else if (inst_list->size() == 0)
 198                 return;
 199
 200         /* start linking */
 201         sllnode<FuncInst *>* it = inst_list->begin();
 202         sllnode<FuncInst *>* prev;
 203
 204         /* add the first instruction to the list of entry insts */
 205         FuncInst * entry_inst = it->getVal();
 206         add_entry_inst(entry_inst);
 207
 208         it = it->getNext();
 209         while (it != NULL) {
 210                 prev = it->getPrev();
 211
 212                 FuncInst * prev_inst = prev->getVal();
 213                 FuncInst * curr_inst = it->getVal();
 214
 215                 prev_inst->add_succ(curr_inst);
 216                 curr_inst->add_pred(prev_inst);
 217
 218                 it = it->getNext();
 219         }
 220 }
 221
 222 void FuncNode::update_predicate_tree(action_list_t * act_list)
 223 {
 224         if (act_list == NULL || act_list->size() == 0)
 225                 return;
 226
 227         /* map a FuncInst to the its predicate */
 228         HashTable<FuncInst *, Predicate *, uintptr_t, 0> inst_pred_map(128);
 229
 230         // number FuncInsts to detect loops
 231         HashTable<FuncInst *, uint32_t, uintptr_t, 0> inst_id_map(128);
 232         uint32_t inst_counter = 0;
 233
 234         HashTable<void *, ModelAction *, uintptr_t, 0> loc_act_map(128);
 235         HashTable<FuncInst *, ModelAction *, uintptr_t, 0> inst_act_map(128);
 236
 237         sllnode<ModelAction *> *it = act_list->begin();
 238         Predicate * curr_pred = predicate_tree_entry;
 239         while (it != NULL) {
 240                 ModelAction * next_act = it->getVal();
 241                 FuncInst * next_inst = get_inst(next_act);
 242
 243                 SnapVector<Predicate *> unset_predicates = SnapVector<Predicate *>();
 244                 bool branch_found = follow_branch(&curr_pred, next_inst, next_act, &inst_act_map, &unset_predicates);
 245
 246                 // A branch with unset predicate expression is detected
 247                 if (!branch_found && unset_predicates.size() != 0) {
 248                         ASSERT(unset_predicates.size() == 1);
 249                         Predicate * one_branch = unset_predicates[0];
 250
 251                         bool amended = amend_predicate_expr(&curr_pred, next_inst, next_act);
 252                         if (amended)
 253                                 continue;
 254                         else {
 255                                 curr_pred = one_branch;
 256                                 branch_found = true;
 257                         }
 258                 }
 259
 260                 // Detect loops
 261                 if (!branch_found && inst_id_map.contains(next_inst)) {
 262                         FuncInst * curr_inst = curr_pred->get_func_inst();
 263                         uint32_t curr_id = inst_id_map.get(curr_inst);
 264                         uint32_t next_id = inst_id_map.get(next_inst);
 265
 266                         if (curr_id >= next_id) {
 267                                 Predicate * old_pred = inst_pred_map.get(next_inst);
 268                                 Predicate * back_pred = old_pred->get_parent();
 269
 270                                 curr_pred->add_backedge(back_pred);
 271                                 curr_pred = back_pred;
 272
 273                                 continue;
 274                         }
 275                 }
 276
 277                 // Generate new branches
 278                 if (!branch_found) {
 279                         SnapVector<struct half_pred_expr *> half_pred_expressions;
 280                         infer_predicates(next_inst, next_act, &loc_act_map, &half_pred_expressions);
 281                         generate_predicates(&curr_pred, next_inst, &half_pred_expressions);
 282                         continue;
 283                 }
 284
 285                 if (next_act->is_write())
 286                         curr_pred->set_write(true);
 287
 288                 inst_pred_map.put(next_inst, curr_pred);
 289                 if (!inst_id_map.contains(next_inst))
 290                         inst_id_map.put(next_inst, inst_counter++);
 291
 292                 loc_act_map.put(next_act->get_location(), next_act);
 293                 inst_act_map.put(next_inst, next_act);
 294                 it = it->getNext();
 295         }
 296 }
 297
 298 /* Given curr_pred and next_inst, find the branch following curr_pred that
 299  * contains next_inst and the correct predicate.
 300  * @return true if branch found, false otherwise.
 301  */
 302 bool FuncNode::follow_branch(Predicate ** curr_pred, FuncInst * next_inst, ModelAction * next_act,
 303         HashTable<FuncInst *, ModelAction *, uintptr_t, 0> * inst_act_map,
 304         SnapVector<Predicate *> * unset_predicates)
 305 {
 306         /* check if a branch with func_inst and corresponding predicate exists */
 307         bool branch_found = false;
 308         ModelVector<Predicate *> * branches = (*curr_pred)->get_children();
 309         for (uint i = 0; i < branches->size(); i++) {
 310                 Predicate * branch = (*branches)[i];
 311                 if (branch->get_func_inst() != next_inst)
 312                         continue;
 313
 314                 /* check against predicate expressions */
 315                 bool predicate_correct = true;
 316                 PredExprSet * pred_expressions = branch->get_pred_expressions();
 317                 PredExprSetIter * pred_expr_it = pred_expressions->iterator();
 318
 319                 /* Only read and rmw actions my have unset predicate expressions */
 320                 if (pred_expressions->getSize() == 0) {
 321                         predicate_correct = false;
 322                         unset_predicates->push_back(branch);
 323                 }
 324
 325                 while (pred_expr_it->hasNext()) {
 326                         pred_expr * pred_expression = pred_expr_it->next();
 327                         uint64_t last_read, next_read;
 328                         bool equality;
 329
 330                         switch(pred_expression->token) {
 331                                 case NOPREDICATE:
 332                                         predicate_correct = true;
 333                                         break;
 334                                 case EQUALITY:
 335                                         FuncInst * to_be_compared;
 336                                         ModelAction * last_act;
 337
 338                                         to_be_compared = pred_expression->func_inst;
 339                                         last_act = inst_act_map->get(to_be_compared);
 340
 341                                         last_read = last_act->get_reads_from_value();
 342                                         next_read = next_act->get_reads_from_value();
 343                                         equality = (last_read == next_read);
 344                                         if (equality != pred_expression->value)
 345                                                 predicate_correct = false;
 346
 347                                         break;
 348                                 case NULLITY:
 349                                         next_read = next_act->get_reads_from_value();
 350                                         equality = ((void*)next_read == NULL);
 351                                         if (equality != pred_expression->value)
 352                                                 predicate_correct = false;
 353                                         break;
 354                                 default:
 355                                         predicate_correct = false;
 356                                         model_print("unkown predicate token\n");
 357                                         break;
 358                         }
 359                 }
 360
 361                 if (predicate_correct) {
 362                         *curr_pred = branch;
 363                         branch_found = true;
 364                         break;
 365                 }
 366         }
 367
 368         return branch_found;
 369 }
 370
 371 /* Infer predicate expressions, which are generated in FuncNode::generate_predicates */
 372 void FuncNode::infer_predicates(FuncInst * next_inst, ModelAction * next_act,
 373         HashTable<void *, ModelAction *, uintptr_t, 0> * loc_act_map,
 374         SnapVector<struct half_pred_expr *> * half_pred_expressions)
 375 {
 376         void * loc = next_act->get_location();
 377
 378         if (next_inst->is_read()) {
 379                 /* read + rmw */
 380                 if ( loc_act_map->contains(loc) ) {
 381                         ModelAction * last_act = loc_act_map->get(loc);
 382                         FuncInst * last_inst = get_inst(last_act);
 383                         struct half_pred_expr * expression = new half_pred_expr(EQUALITY, last_inst);
 384                         half_pred_expressions->push_back(expression);
 385                 } else if ( next_inst->is_single_location() ){
 386                         loc_set_t * loc_may_equal = loc_may_equal_map->get(loc);
 387
 388                         if (loc_may_equal != NULL) {
 389                                 loc_set_iter * loc_it = loc_may_equal->iterator();
 390                                 while (loc_it->hasNext()) {
 391                                         void * neighbor = loc_it->next();
 392                                         if (loc_act_map->contains(neighbor)) {
 393                                                 ModelAction * last_act = loc_act_map->get(neighbor);
 394                                                 FuncInst * last_inst = get_inst(last_act);
 395
 396                                                 struct half_pred_expr * expression = new half_pred_expr(EQUALITY, last_inst);
 397                                                 half_pred_expressions->push_back(expression);
 398                                         }
 399                                 }
 400                         }
 401                 } else {
 402                         // next_inst is not single location
 403                         uint64_t read_val = next_act->get_reads_from_value();
 404
 405                         // only infer NULLITY predicate when it is actually NULL.
 406                         if ( (void*)read_val == NULL) {
 407                                 struct half_pred_expr * expression = new half_pred_expr(NULLITY, NULL);
 408                                 half_pred_expressions->push_back(expression);
 409                         }
 410                 }
 411         } else {
 412                 /* Pure writes */
 413                 // TODO: do anything here?
 414         }
 415 }
 416
 417 /* Able to generate complex predicates when there are multiple predciate expressions */
 418 void FuncNode::generate_predicates(Predicate ** curr_pred, FuncInst * next_inst,
 419         SnapVector<struct half_pred_expr *> * half_pred_expressions)
 420 {
 421         if (half_pred_expressions->size() == 0) {
 422                 Predicate * new_pred = new Predicate(next_inst);
 423                 (*curr_pred)->add_child(new_pred);
 424                 new_pred->set_parent(*curr_pred);
 425
 426                 /* entry predicates and predicates containing pure write actions
 427                  * have no predicate expressions */
 428                 if ( (*curr_pred)->is_entry_predicate() )
 429                         new_pred->add_predicate_expr(NOPREDICATE, NULL, true);
 430                 else if (next_inst->is_write()) {
 431                         /* next_inst->is_write() <==> pure writes */
 432                         new_pred->add_predicate_expr(NOPREDICATE, NULL, true);
 433                 }
 434
 435                 return;
 436         }
 437
 438         SnapVector<Predicate *> predicates;
 439
 440         struct half_pred_expr * half_expr = (*half_pred_expressions)[0];
 441         predicates.push_back(new Predicate(next_inst));
 442         predicates.push_back(new Predicate(next_inst));
 443
 444         predicates[0]->add_predicate_expr(half_expr->token, half_expr->func_inst, true);
 445         predicates[1]->add_predicate_expr(half_expr->token, half_expr->func_inst, false);
 446
 447         for (uint i = 1; i < half_pred_expressions->size(); i++) {
 448                 half_expr = (*half_pred_expressions)[i];
 449
 450                 uint old_size = predicates.size();
 451                 for (uint j = 0; j < old_size; j++) {
 452                         Predicate * pred = predicates[j];
 453                         Predicate * new_pred = new Predicate(next_inst);
 454                         new_pred->copy_predicate_expr(pred);
 455
 456                         pred->add_predicate_expr(half_expr->token, half_expr->func_inst, true);
 457                         new_pred->add_predicate_expr(half_expr->token, half_expr->func_inst, false);
 458
 459                         predicates.push_back(new_pred);
 460                 }
 461         }
 462
 463         for (uint i = 0; i < predicates.size(); i++) {
 464                 Predicate * pred= predicates[i];
 465                 (*curr_pred)->add_child(pred);
 466                 pred->set_parent(*curr_pred);
 467         }
 468 }
 469
 470 /* Amend predicates that contain no predicate expressions. Currenlty only amend with NULLITY predicates */
 471 bool FuncNode::amend_predicate_expr(Predicate ** curr_pred, FuncInst * next_inst, ModelAction * next_act)
 472 {
 473         // there should only be only child
 474         Predicate * unset_pred = (*curr_pred)->get_children()->back();
 475         uint64_t read_val = next_act->get_reads_from_value();
 476
 477         // only generate NULLITY predicate when it is actually NULL.
 478         if ( !next_inst->is_single_location() && (void*)read_val == NULL ) {
 479                 Predicate * new_pred = new Predicate(next_inst);
 480
 481                 (*curr_pred)->add_child(new_pred);
 482                 new_pred->set_parent(*curr_pred);
 483
 484                 unset_pred->add_predicate_expr(NULLITY, NULL, false);
 485                 new_pred->add_predicate_expr(NULLITY, NULL, true);
 486
 487                 return true;
 488         }
 489
 490         return false;
 491 }
 492
 493 void FuncNode::add_to_val_loc_map(uint64_t val, void * loc)
 494 {
 495         loc_set_t * locations = val_loc_map->get(val);
 496
 497         if (locations == NULL) {
 498                 locations = new loc_set_t();
 499                 val_loc_map->put(val, locations);
 500         }
 501
 502         update_loc_may_equal_map(loc, locations);
 503         locations->add(loc);
 504         // values_may_read_from->add(val);
 505 }
 506
 507 void FuncNode::add_to_val_loc_map(value_set_t * values, void * loc)
 508 {
 509         if (values == NULL)
 510                 return;
 511
 512         value_set_iter * it = values->iterator();
 513         while (it->hasNext()) {
 514                 uint64_t val = it->next();
 515                 add_to_val_loc_map(val, loc);
 516         }
 517 }
 518
 519 void FuncNode::update_loc_may_equal_map(void * new_loc, loc_set_t * old_locations)
 520 {
 521         if ( old_locations->contains(new_loc) )
 522                 return;
 523
 524         loc_set_t * neighbors = loc_may_equal_map->get(new_loc);
 525
 526         if (neighbors == NULL) {
 527                 neighbors = new loc_set_t();
 528                 loc_may_equal_map->put(new_loc, neighbors);
 529         }
 530
 531         loc_set_iter * loc_it = old_locations->iterator();
 532         while (loc_it->hasNext()) {
 533                 // new_loc: { old_locations, ... }
 534                 void * member = loc_it->next();
 535                 neighbors->add(member);
 536
 537                 // for each i in old_locations, i : { new_loc, ... }
 538                 loc_set_t * _neighbors = loc_may_equal_map->get(member);
 539                 if (_neighbors == NULL) {
 540                         _neighbors = new loc_set_t();
 541                         loc_may_equal_map->put(member, _neighbors);
 542                 }
 543                 _neighbors->add(new_loc);
 544         }
 545 }
 546
 547 /* Every time a thread enters a function, set its position to the predicate tree entry */
 548 void FuncNode::init_predicate_tree_position(thread_id_t tid)
 549 {
 550         int thread_id = id_to_int(tid);
 551         if (predicate_tree_position.size() <= (uint) thread_id)
 552                 predicate_tree_position.resize(thread_id + 1);
 553
 554         predicate_tree_position[thread_id] = predicate_tree_entry;
 555 }
 556
 557 void FuncNode::set_predicate_tree_position(thread_id_t tid, Predicate * pred)
 558 {
 559         int thread_id = id_to_int(tid);
 560         predicate_tree_position[thread_id] = pred;
 561 }
 562
 563 /* @return The position of a thread in a predicate tree */
 564 Predicate * FuncNode::get_predicate_tree_position(thread_id_t tid)
 565 {
 566         int thread_id = id_to_int(tid);
 567         return predicate_tree_position[thread_id];
 568 }
 569
 570 /* Make sure elements of thrd_inst_act_map are initialized properly when threads enter functions */
 571 void FuncNode::init_inst_act_map(thread_id_t tid)
 572 {
 573         int thread_id = id_to_int(tid);
 574         uint old_size = thrd_inst_act_map->size();
 575
 576         if (thrd_inst_act_map->size() <= (uint) thread_id) {
 577                 uint new_size = thread_id + 1;
 578                 thrd_inst_act_map->resize(new_size);
 579
 580                 for (uint i = old_size; i < new_size; i++)
 581                         (*thrd_inst_act_map)[i] = new inst_act_map_t(128);
 582         }
 583 }
 584
 585 /* Reset elements of thrd_inst_act_map when threads exit functions */
 586 void FuncNode::reset_inst_act_map(thread_id_t tid)
 587 {
 588         int thread_id = id_to_int(tid);
 589         inst_act_map_t * map = (*thrd_inst_act_map)[thread_id];
 590         map->reset();
 591 }
 592
 593 void FuncNode::update_inst_act_map(thread_id_t tid, ModelAction * read_act)
 594 {
 595         int thread_id = id_to_int(tid);
 596         inst_act_map_t * map = (*thrd_inst_act_map)[thread_id];
 597         FuncInst * read_inst = get_inst(read_act);
 598         map->put(read_inst, read_act);
 599 }
 600
 601 inst_act_map_t * FuncNode::get_inst_act_map(thread_id_t tid)
 602 {
 603         int thread_id = id_to_int(tid);
 604         return (*thrd_inst_act_map)[thread_id];
 605 }
 606
 607 /* Add FuncNodes that this node may follow */
 608 void FuncNode::add_out_edge(FuncNode * other)
 609 {
 610         if ( !edge_table.contains(other) ) {
 611                 edge_table.put(other, OUT_EDGE);
 612                 out_edges.push_back(other);
 613                 return;
 614         }
 615
 616         edge_type_t edge = edge_table.get(other);
 617         if (edge == IN_EDGE) {
 618                 edge_table.put(other, BI_EDGE);
 619                 out_edges.push_back(other);
 620         }
 621 }
 622
 623 void FuncNode::print_predicate_tree()
 624 {
 625         model_print("digraph function_%s {\n", func_name);
 626         predicate_tree_entry->print_pred_subtree();
 627         model_print("}\n");     // end of graph
 628 }
 629
 630 void FuncNode::print_val_loc_map()
 631 {
 632 /*
 633         value_set_iter * val_it = values_may_read_from->iterator();
 634         while (val_it->hasNext()) {
 635                 uint64_t value = val_it->next();
 636                 model_print("val %llx: ", value);
 637
 638                 loc_set_t * locations = val_loc_map->get(value);
 639                 loc_set_iter * loc_it = locations->iterator();
 640                 while (loc_it->hasNext()) {
 641                         void * location = loc_it->next();
 642                         model_print("%p ", location);
 643                 }
 644                 model_print("\n");
 645         }
 646 */
 647 }