smatch_slist.c

   1 /*
   2  * sparse/smatch_slist.c
   3  *
   4  * Copyright (C) 2008,2009 Dan Carpenter.
   5  *
   6  *  Licensed under the Open Software License version 1.1
   7  *
   8  */
   9
  10 #include <stdlib.h>
  11 #include <stdio.h>
  12 #include "smatch.h"
  13 #include "smatch_slist.h"
  14
  15 #undef CHECKORDER
  16
  17 ALLOCATOR(sm_state, "smatch state");
  18 ALLOCATOR(named_slist, "named slist");
  19
  20 void __print_slist(struct state_list *slist)
  21 {
  22         struct sm_state *state;
  23         struct sm_state *poss;
  24         int i;
  25
  26         printf("dumping slist at %d\n", get_lineno());
  27         FOR_EACH_PTR(slist, state) {
  28                 printf("%d '%s'=%s (", state->owner, state->name,
  29                         show_state(state->state));
  30                 i = 0;
  31                 FOR_EACH_PTR(state->possible, poss) {
  32                         if (i++)
  33                                 printf(", ");
  34                         printf("%s", show_state(poss->state));
  35                 } END_FOR_EACH_PTR(poss);
  36                 printf(")\n");
  37         } END_FOR_EACH_PTR(state);
  38         printf("---\n");
  39 }
  40
  41
  42 /* NULL states go at the end to simplify merge_slist */
  43 int cmp_tracker(const struct sm_state *a, const struct sm_state *b)
  44 {
  45         int ret;
  46
  47         if (!a && !b)
  48                 return 0;
  49         if (!b)
  50                 return -1;
  51         if (!a)
  52                 return 1;
  53
  54         if (a->owner > b->owner)
  55                 return -1;
  56         if (a->owner < b->owner)
  57                 return 1;
  58
  59         ret = strcmp(a->name, b->name);
  60         if (ret)
  61                 return ret;
  62
  63         if (!b->sym && a->sym)
  64                 return -1;
  65         if (!a->sym && b->sym)
  66                 return 1;
  67         if (a->sym > b->sym)
  68                 return -1;
  69         if (a->sym < b->sym)
  70                 return 1;
  71
  72         return 0;
  73 }
  74
  75 static int cmp_sm_states(const struct sm_state *a, const struct sm_state *b)
  76 {
  77         int ret;
  78
  79         ret = cmp_tracker(a, b);
  80         if (ret)
  81                 return ret;
  82
  83         /* todo:  add hook for smatch_extra.c */
  84         if (a->state > b->state)
  85                 return -1;
  86         if (a->state < b->state)
  87                 return 1;
  88         return 0;
  89 }
  90
  91 void add_sm_state_slist(struct state_list **slist, struct sm_state *new)
  92 {
  93         struct sm_state *tmp;
  94
  95         FOR_EACH_PTR(*slist, tmp) {
  96                 if (cmp_sm_states(tmp, new) < 0)
  97                         continue;
  98                 else if (cmp_sm_states(tmp, new) == 0) {
  99                         return;
 100                 } else {
 101                         INSERT_CURRENT(new, tmp);
 102                         return;
 103                 }
 104         } END_FOR_EACH_PTR(tmp);
 105         add_ptr_list(slist, new);
 106 }
 107
 108 static void add_possible(struct sm_state *sm, struct sm_state *new)
 109 {
 110         struct sm_state *tmp;
 111         struct sm_state *tmp2;
 112
 113         if (!new) {
 114                 struct smatch_state *s;
 115
 116                 s = merge_states(sm->name, sm->owner, sm->sym, sm->state, NULL);
 117                 tmp = alloc_state(sm->name, sm->owner, sm->sym, s);
 118                 add_sm_state_slist(&sm->possible, tmp);
 119                 return;
 120         }
 121
 122         FOR_EACH_PTR(new->possible, tmp) {
 123                 tmp2 = alloc_state(tmp->name, tmp->owner, tmp->sym, tmp->state);
 124                 add_sm_state_slist(&sm->possible, tmp2);
 125         } END_FOR_EACH_PTR(tmp);
 126 }
 127
 128 struct sm_state *alloc_state(const char *name, int owner,
 129                              struct symbol *sym, struct smatch_state *state)
 130 {
 131         struct sm_state *sm_state = __alloc_sm_state(0);
 132
 133         sm_state->name = (char *)name;
 134         sm_state->owner = owner;
 135         sm_state->sym = sym;
 136         sm_state->state = state;
 137         sm_state->my_pools = NULL;
 138         sm_state->all_pools = NULL;
 139         sm_state->possible = NULL;
 140         add_ptr_list(&sm_state->possible, sm_state);
 141         return sm_state;
 142 }
 143
 144 /* At the end of every function we free all the sm_states */
 145 void free_every_single_sm_state()
 146 {
 147         struct allocator_struct *desc = &sm_state_allocator;
 148         struct allocation_blob *blob = desc->blobs;
 149
 150         desc->blobs = NULL;
 151         desc->allocations = 0;
 152         desc->total_bytes = 0;
 153         desc->useful_bytes = 0;
 154         desc->freelist = NULL;
 155         while (blob) {
 156                 struct allocation_blob *next = blob->next;
 157                 struct sm_state *sm = (struct sm_state *)blob->data;
 158
 159                 free_slist(&sm->possible);
 160                 free_stack(&sm->my_pools);
 161                 free_stack(&sm->all_pools);
 162                 blob_free(blob, desc->chunking);
 163                 blob = next;
 164         }
 165 }
 166
 167 struct sm_state *clone_state(struct sm_state *s)
 168 {
 169         struct sm_state *ret;
 170         struct sm_state *poss;
 171
 172         ret = alloc_state(s->name, s->owner, s->sym, s->state);
 173         ret->my_pools = clone_stack(s->my_pools);
 174         ret->all_pools = clone_stack(s->all_pools);
 175         FOR_EACH_PTR(s->possible, poss) {
 176                 add_sm_state_slist(&ret->possible, poss);
 177         } END_FOR_EACH_PTR(poss);
 178         return ret;
 179 }
 180
 181 int slist_has_state(struct state_list *slist, struct smatch_state *state)
 182 {
 183         struct sm_state *tmp;
 184
 185         FOR_EACH_PTR(slist, tmp) {
 186                 if (tmp->state == state)
 187                         return 1;
 188         } END_FOR_EACH_PTR(tmp);
 189         return 0;
 190 }
 191
 192 #ifdef CHECKORDER
 193 static void check_order(struct state_list *slist)
 194 {
 195         struct sm_state *state;
 196         struct sm_state *last = NULL;
 197         int printed = 0;
 198
 199         FOR_EACH_PTR(slist, state) {
 200                 if (last && cmp_tracker(state, last) <= 0) {
 201                         printf("Error.  Unsorted slist %d vs %d, %p vs %p, "
 202                                "%s vs %s\n", last->owner, state->owner,
 203                                last->sym, state->sym, last->name, state->name);
 204                         printed = 1;
 205                 }
 206                 last = state;
 207         } END_FOR_EACH_PTR(state);
 208
 209         if (printed)
 210                 printf("======\n");
 211 }
 212 #endif
 213
 214 struct state_list *clone_slist(struct state_list *from_slist)
 215 {
 216         struct sm_state *state;
 217         struct sm_state *tmp;
 218         struct state_list *to_slist = NULL;
 219
 220         FOR_EACH_PTR(from_slist, state) {
 221                 tmp = clone_state(state);
 222                 add_ptr_list(&to_slist, tmp);
 223         } END_FOR_EACH_PTR(state);
 224 #ifdef CHECKORDER
 225         check_order(to_slist);
 226 #endif
 227         return to_slist;
 228 }
 229
 230 struct state_list_stack *clone_stack(struct state_list_stack *from_stack)
 231 {
 232         struct state_list *slist;
 233         struct state_list_stack *to_stack = NULL;
 234
 235         FOR_EACH_PTR(from_stack, slist) {
 236                 push_slist(&to_stack, slist);
 237         } END_FOR_EACH_PTR(slist);
 238         return to_stack;
 239 }
 240
 241 struct smatch_state *merge_states(const char *name, int owner,
 242                                   struct symbol *sym,
 243                                   struct smatch_state *state1,
 244                                   struct smatch_state *state2)
 245 {
 246         struct smatch_state *ret;
 247
 248         if (state1 == state2)
 249                 ret = state1;
 250         else if (__has_merge_function(owner))
 251                 ret = __client_merge_function(owner, name, sym, state1, state2);
 252         else if (!state1 || !state2)
 253                 ret = &undefined;
 254         else
 255                 ret = &merged;
 256         return ret;
 257 }
 258
 259 /*
 260  * add_pool() adds a slist to ->pools. If the slist has already been
 261  * added earlier then it doesn't get added a second time.
 262  */
 263 static void add_pool(struct state_list_stack **pools, struct state_list *new)
 264 {
 265         struct state_list *tmp;
 266
 267         FOR_EACH_PTR(*pools, tmp) {
 268                 if (tmp < new)
 269                         continue;
 270                 else if (tmp == new) {
 271                         return;
 272                 } else {
 273                         INSERT_CURRENT(new, tmp);
 274                         return;
 275                 }
 276         } END_FOR_EACH_PTR(tmp);
 277         add_ptr_list(pools, new);
 278 }
 279
 280 static void copy_pools(struct sm_state *to, struct sm_state *sm)
 281 {
 282         struct state_list *tmp;
 283
 284         if (!sm)
 285                 return;
 286
 287         FOR_EACH_PTR(sm->my_pools, tmp) {
 288                 add_pool(&to->my_pools, tmp);
 289         } END_FOR_EACH_PTR(tmp);
 290
 291         FOR_EACH_PTR(sm->all_pools, tmp) {
 292                 add_pool(&to->all_pools, tmp);
 293         } END_FOR_EACH_PTR(tmp);
 294 }
 295
 296 struct sm_state *merge_sm_states(struct sm_state *one, struct sm_state *two)
 297 {
 298         struct smatch_state *s;
 299         struct sm_state *result;
 300
 301         s = merge_states(one->name, one->owner, one->sym, one->state,
 302                         (two?two->state:NULL));
 303         result = alloc_state(one->name, one->owner, one->sym, s);
 304         add_possible(result, one);
 305         add_possible(result, two);
 306         copy_pools(result, one);
 307         copy_pools(result, two);
 308
 309         if (debug_states) {
 310                 struct sm_state *tmp;
 311                 int i = 0;
 312
 313                 printf("%d merge name='%s' owner=%d: %s + %s => %s (",
 314                         get_lineno(), one->name, one->owner,
 315                         show_state(one->state), show_state(two?two->state:NULL),
 316                         show_state(s));
 317
 318                 FOR_EACH_PTR(result->possible, tmp) {
 319                         if (i++) {
 320                                 printf(", ");
 321                         }
 322                         printf("%s", show_state(tmp->state));
 323                 } END_FOR_EACH_PTR(tmp);
 324                 printf(")\n");
 325         }
 326
 327         return result;
 328 }
 329
 330 struct sm_state *get_sm_state_slist(struct state_list *slist, const char *name,
 331                                 int owner, struct symbol *sym)
 332 {
 333         struct sm_state *state;
 334
 335         if (!name)
 336                 return NULL;
 337
 338         FOR_EACH_PTR(slist, state) {
 339                 if (state->owner == owner && state->sym == sym
 340                     && !strcmp(state->name, name))
 341                         return state;
 342         } END_FOR_EACH_PTR(state);
 343         return NULL;
 344 }
 345
 346 struct smatch_state *get_state_slist(struct state_list *slist,
 347                                 const char *name, int owner,
 348                                 struct symbol *sym)
 349 {
 350         struct sm_state *state;
 351
 352         state = get_sm_state_slist(slist, name, owner, sym);
 353         if (state)
 354                 return state->state;
 355         return NULL;
 356 }
 357
 358 void overwrite_sm_state(struct state_list **slist, struct sm_state *new)
 359 {
 360         struct sm_state *tmp;
 361
 362         FOR_EACH_PTR(*slist, tmp) {
 363                 if (cmp_tracker(tmp, new) < 0)
 364                         continue;
 365                 else if (cmp_tracker(tmp, new) == 0) {
 366                         REPLACE_CURRENT_PTR(tmp, new);
 367                         return;
 368                 } else {
 369                         INSERT_CURRENT(new, tmp);
 370                         return;
 371                 }
 372         } END_FOR_EACH_PTR(tmp);
 373         add_ptr_list(slist, new);
 374 }
 375
 376 void overwrite_sm_state_stack(struct state_list_stack **stack,
 377                         struct sm_state *state)
 378 {
 379         struct state_list *slist;
 380
 381         slist = pop_slist(stack);
 382         overwrite_sm_state(&slist, state);
 383         push_slist(stack, slist);
 384 }
 385
 386 void set_state_slist(struct state_list **slist, const char *name, int owner,
 387                      struct symbol *sym, struct smatch_state *state)
 388 {
 389         struct sm_state *tmp;
 390         struct sm_state *new = alloc_state(name, owner, sym, state);
 391
 392         FOR_EACH_PTR(*slist, tmp) {
 393                 if (cmp_tracker(tmp, new) < 0)
 394                         continue;
 395                 else if (cmp_tracker(tmp, new) == 0) {
 396                         REPLACE_CURRENT_PTR(tmp, new);
 397                         return;
 398                 } else {
 399                         INSERT_CURRENT(new, tmp);
 400                         return;
 401                 }
 402         } END_FOR_EACH_PTR(tmp);
 403         add_ptr_list(slist, new);
 404 }
 405
 406 void delete_state_slist(struct state_list **slist, const char *name, int owner,
 407                         struct symbol *sym)
 408 {
 409         struct sm_state *state;
 410
 411         FOR_EACH_PTR(*slist, state) {
 412                 if (state->owner == owner && state->sym == sym
 413                     && !strcmp(state->name, name)){
 414                         delete_ptr_list_entry((struct ptr_list **)slist,
 415                                               state, 1);
 416                         return;
 417                 }
 418         } END_FOR_EACH_PTR(state);
 419 }
 420
 421
 422 void push_slist(struct state_list_stack **list_stack, struct state_list *slist)
 423 {
 424         add_ptr_list(list_stack, slist);
 425 }
 426
 427 struct state_list *pop_slist(struct state_list_stack **list_stack)
 428 {
 429         struct state_list *slist;
 430
 431         slist = last_ptr_list((struct ptr_list *)*list_stack);
 432         delete_ptr_list_last((struct ptr_list **)list_stack);
 433         return slist;
 434 }
 435
 436 void free_slist(struct state_list **slist)
 437 {
 438         __free_ptr_list((struct ptr_list **)slist);
 439 }
 440
 441 void free_stack(struct state_list_stack **stack)
 442 {
 443         __free_ptr_list((struct ptr_list **)stack);
 444 }
 445
 446 void free_stack_and_slists(struct state_list_stack **slist_stack)
 447 {
 448         struct state_list *slist;
 449
 450         FOR_EACH_PTR(*slist_stack, slist) {
 451                 free_slist(&slist);
 452         } END_FOR_EACH_PTR(slist);
 453         free_stack(slist_stack);
 454 }
 455
 456 /*
 457  * set_state_stack() sets the state for the top slist on the stack.
 458  */
 459 void set_state_stack(struct state_list_stack **stack, const char *name,
 460                      int owner, struct symbol *sym, struct smatch_state *state)
 461 {
 462         struct state_list *slist;
 463
 464         slist = pop_slist(stack);
 465         set_state_slist(&slist, name, owner, sym, state);
 466         push_slist(stack, slist);
 467 }
 468
 469 /*
 470  * get_state_stack() gets the state for the top slist on the stack.
 471  */
 472 struct smatch_state *get_state_stack(struct state_list_stack *stack,
 473                                      const char *name, int owner,
 474                                      struct symbol *sym)
 475 {
 476         struct state_list *slist;
 477         struct smatch_state *ret;
 478
 479         slist = pop_slist(&stack);
 480         ret = get_state_slist(slist, name, owner, sym);
 481         push_slist(&stack, slist);
 482         return ret;
 483 }
 484
 485 /*
 486  * We want to find which states have been modified inside a branch.
 487  * If you have 2 &merged states they could be different states really
 488  * and maybe one or both were modified.  We say it is unchanged if
 489  * the ->state pointers are the same and they belong to the same pools.
 490  * If they have been modified on both sides of a branch to the same thing,
 491  * it's still OK to say they are the same, because that means they won't
 492  * belong to any pools.
 493  */
 494 static int is_really_same(struct sm_state *one, struct sm_state *two)
 495 {
 496         struct state_list *tmp1;
 497         struct state_list *tmp2;
 498
 499         if (one->state != two->state)
 500                 return 0;
 501
 502         PREPARE_PTR_LIST(one->my_pools, tmp1);
 503         PREPARE_PTR_LIST(two->my_pools, tmp2);
 504         for (;;) {
 505                 if (!tmp1 && !tmp2)
 506                         return 1;
 507                 if (tmp1 < tmp2) {
 508                         return 0;
 509                 } else if (tmp1 == tmp2) {
 510                         NEXT_PTR_LIST(tmp1);
 511                         NEXT_PTR_LIST(tmp2);
 512                 } else {
 513                         return 0;
 514                 }
 515         }
 516         FINISH_PTR_LIST(tmp2);
 517         FINISH_PTR_LIST(tmp1);
 518         return 1;
 519 }
 520
 521 /*
 522  * merge_slist() is called whenever paths merge, such as after
 523  * an if statement.  It takes the two slists and creates one.
 524  */
 525 void merge_slist(struct state_list **to, struct state_list *slist)
 526 {
 527         struct sm_state *to_state, *state, *tmp;
 528         struct state_list *results = NULL;
 529         struct state_list *implied_to = NULL;
 530         struct state_list *implied_from = NULL;
 531
 532 #ifdef CHECKORDER
 533         check_order(*to);
 534         check_order(slist);
 535 #endif
 536
 537         /* merging a null and nonnull path gives you only the nonnull path */
 538         if (!slist) {
 539                 return;
 540         }
 541         if (!*to) {
 542                 *to = clone_slist(slist);
 543                 return;
 544         }
 545
 546         implied_to = clone_slist(*to);
 547         implied_from = clone_slist(slist);
 548
 549         PREPARE_PTR_LIST(*to, to_state);
 550         PREPARE_PTR_LIST(slist, state);
 551         for (;;) {
 552                 if (!to_state && !state)
 553                         break;
 554                 if (cmp_tracker(to_state, state) < 0) {
 555                         tmp = merge_sm_states(to_state, NULL);
 556                         add_pool(&tmp->my_pools, implied_to);
 557                         add_pool(&tmp->all_pools, implied_to);
 558                         add_ptr_list(&results, tmp);
 559                         NEXT_PTR_LIST(to_state);
 560                 } else if (cmp_tracker(to_state, state) == 0) {
 561                         tmp = merge_sm_states(to_state, state);
 562                         if (!is_really_same(to_state, state)) {
 563                                 add_pool(&tmp->my_pools, implied_to);
 564                                 add_pool(&tmp->my_pools, implied_from);
 565                         }
 566                         add_pool(&tmp->all_pools, implied_to);
 567                         add_pool(&tmp->all_pools, implied_from);
 568                         add_ptr_list(&results, tmp);
 569                         NEXT_PTR_LIST(to_state);
 570                         NEXT_PTR_LIST(state);
 571                 } else {
 572                         tmp = merge_sm_states(state, NULL);
 573                         add_pool(&tmp->my_pools, implied_from);
 574                         add_pool(&tmp->all_pools, implied_from);
 575                         add_ptr_list(&results, tmp);
 576                         NEXT_PTR_LIST(state);
 577                 }
 578         }
 579         FINISH_PTR_LIST(state);
 580         FINISH_PTR_LIST(to_state);
 581
 582         free_slist(to);
 583         *to = results;
 584
 585         push_slist(&implied_pools, implied_from);
 586         push_slist(&implied_pools, implied_to);
 587 }
 588
 589 static int pool_in_pools(struct state_list_stack *pools,
 590                         struct state_list *pool)
 591 {
 592         struct state_list *tmp;
 593
 594         FOR_EACH_PTR(pools, tmp) {
 595                 if (tmp == pool)
 596                         return 1;
 597         } END_FOR_EACH_PTR(tmp);
 598         return 0;
 599 }
 600
 601 struct state_list *clone_states_in_pool(struct state_list *pool,
 602                                 struct state_list *cur_slist)
 603 {
 604         struct sm_state *state;
 605         struct sm_state *cur_state;
 606         struct sm_state *tmp;
 607         struct state_list *to_slist = NULL;
 608
 609         FOR_EACH_PTR(pool, state) {
 610                 cur_state = get_sm_state_slist(cur_slist, state->name,
 611                                         state->owner, state->sym);
 612                 if (!cur_state)
 613                         continue;
 614                 if (is_really_same(state, cur_state))
 615                         continue;
 616                 if (pool_in_pools(cur_state->all_pools, pool)) {
 617                         tmp = clone_state(state);
 618                         add_ptr_list(&to_slist, tmp);
 619                 }
 620         } END_FOR_EACH_PTR(state);
 621         return to_slist;
 622 }
 623
 624 /*
 625  * merge_implied() takes an implied state and another possibly implied state
 626  * from another pool.  It checks that the second pool is reachable from
 627  * cur_slist then merges the two states and returns the result.
 628  */
 629 struct sm_state *merge_implied(struct sm_state *one, struct sm_state *two,
 630                                 struct state_list *pool,
 631                                 struct state_list *cur_slist)
 632 {
 633         struct sm_state *cur_state;
 634
 635         cur_state = get_sm_state_slist(cur_slist, two->name, two->owner,
 636                                 two->sym);
 637         if (!cur_state)
 638                 return NULL;  /* this can't actually happen */
 639         if (!pool_in_pools(cur_state->all_pools, pool))
 640                 return NULL;
 641         return merge_sm_states(one, two);
 642 }
 643
 644 /*
 645  * filter() is used to find what states are the same across
 646  * a series of slists.
 647  * It takes a **slist and a *filter.
 648  * It removes everything from **slist that isn't in *filter.
 649  * The reason you would want to do this is if you want to
 650  * know what other states are true if one state is true.  (smatch_implied).
 651  */
 652 void filter(struct state_list **slist, struct state_list *filter,
 653         struct state_list *cur_slist)
 654 {
 655         struct sm_state *s_one, *s_two;
 656         struct state_list *results = NULL;
 657         struct sm_state *tmp;
 658
 659 #ifdef CHECKORDER
 660         check_order(*slist);
 661         check_order(filter);
 662 #endif
 663
 664         PREPARE_PTR_LIST(*slist, s_one);
 665         PREPARE_PTR_LIST(filter, s_two);
 666         for (;;) {
 667                 if (!s_one || !s_two)
 668                         break;
 669                 if (cmp_tracker(s_one, s_two) < 0) {
 670                         NEXT_PTR_LIST(s_one);
 671                 } else if (cmp_tracker(s_one, s_two) == 0) {
 672                         tmp = merge_implied(s_one, s_two, filter, cur_slist);
 673                         if (tmp)
 674                                 add_ptr_list(&results, tmp);
 675                         NEXT_PTR_LIST(s_one);
 676                         NEXT_PTR_LIST(s_two);
 677                 } else {
 678                         NEXT_PTR_LIST(s_two);
 679                 }
 680         }
 681         FINISH_PTR_LIST(s_two);
 682         FINISH_PTR_LIST(s_one);
 683
 684         free_slist(slist);
 685         *slist = results;
 686 }
 687
 688 /*
 689  * and_slist_stack() is basically the same as popping the top two slists,
 690  * overwriting the one with the other and pushing it back on the stack.
 691  * The difference is that it checks to see that a mutually exclusive
 692  * state isn't included in both stacks.  If smatch sees something like
 693  * "if (a && !a)" it prints a warning.
 694  */
 695 void and_slist_stack(struct state_list_stack **slist_stack)
 696 {
 697         struct sm_state *tmp;
 698         struct smatch_state *tmp_state;
 699         struct state_list *tmp_slist = pop_slist(slist_stack);
 700
 701         FOR_EACH_PTR(tmp_slist, tmp) {
 702                 tmp_state = get_state_stack(*slist_stack, tmp->name,
 703                                             tmp->owner, tmp->sym);
 704                 if (tmp_state && tmp_state != tmp->state) {
 705                         smatch_msg("mutually exclusive 'and' conditions states "
 706                                 "'%s': %s + %s",
 707                                 tmp->name, show_state(tmp_state),
 708                                 show_state(tmp->state));
 709                 }
 710                 set_state_stack(slist_stack, tmp->name, tmp->owner, tmp->sym,
 711                                 tmp->state);
 712         } END_FOR_EACH_PTR(tmp);
 713         free_slist(&tmp_slist);
 714 }
 715
 716 /*
 717  * or_slist_stack() is for if we have:  if (foo || bar) { foo->baz;
 718  * It pops the two slists from the top of the stack and merges them
 719  * together in a way that preserves the things they have in common
 720  * but creates a merged state for most of the rest.
 721  * You could have code that had:  if (foo || foo) { foo->baz;
 722  * It's this function which ensures smatch does the right thing.
 723  */
 724 void or_slist_stack(struct state_list_stack **slist_stack)
 725 {
 726         struct state_list *one;
 727         struct state_list *two;
 728         struct state_list *res = NULL;
 729         struct sm_state *tmp;
 730         struct sm_state *sm;
 731         struct sm_state *new_sm;
 732
 733         one = pop_slist(slist_stack);
 734         two = pop_slist(slist_stack);
 735
 736         FOR_EACH_PTR(one, tmp) {
 737                 sm = get_sm_state_slist(two, tmp->name, tmp->owner, tmp->sym);
 738                 new_sm = merge_sm_states(tmp, sm);
 739                 add_ptr_list(&res, new_sm);
 740         } END_FOR_EACH_PTR(tmp);
 741
 742         FOR_EACH_PTR(two, tmp) {
 743                 sm = get_sm_state_slist(one, tmp->name, tmp->owner, tmp->sym);
 744                 new_sm = merge_sm_states(tmp, sm);
 745                 add_ptr_list(&res, new_sm);
 746         } END_FOR_EACH_PTR(tmp);
 747
 748         push_slist(slist_stack, res);
 749
 750         free_slist(&one);
 751         free_slist(&two);
 752 }
 753
 754 /*
 755  * get_slist_from_named_stack() is only used for gotos.
 756  */
 757 struct state_list **get_slist_from_named_stack(struct named_stack *stack,
 758                                               const char *name)
 759 {
 760         struct named_slist *tmp;
 761
 762         FOR_EACH_PTR(stack, tmp) {
 763                 if (!strcmp(tmp->name, name))
 764                         return &tmp->slist;
 765         } END_FOR_EACH_PTR(tmp);
 766         return NULL;
 767 }
 768
 769 void overwrite_slist(struct state_list *from, struct state_list **to)
 770 {
 771         struct sm_state *tmp;
 772
 773         FOR_EACH_PTR(from, tmp) {
 774                 overwrite_sm_state(to, tmp);
 775         } END_FOR_EACH_PTR(tmp);
 776 }