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(smatch_state, "smatch state");
  18 ALLOCATOR(sm_state, "sm state");
  19 ALLOCATOR(named_slist, "named slist");
  20 __DO_ALLOCATOR(char, 0, 1, "state names", sname);
  21
  22 static int sm_state_counter;
  23
  24 char *show_sm(struct sm_state *sm)
  25 {
  26         static char buf[256];
  27         struct sm_state *tmp;
  28         int pos;
  29         int i;
  30
  31         pos = snprintf(buf, sizeof(buf), "[%s] '%s' = %s (",
  32                        check_name(sm->owner), sm->name, show_state(sm->state));
  33         if (pos > sizeof(buf))
  34                 goto truncate;
  35
  36         i = 0;
  37         FOR_EACH_PTR(sm->possible, tmp) {
  38                 if (i++)
  39                         pos += snprintf(buf + pos, sizeof(buf) - pos, ", ");
  40                 if (pos > sizeof(buf))
  41                         goto truncate;
  42                 pos += snprintf(buf + pos, sizeof(buf) - pos, "%s",
  43                                show_state(tmp->state));
  44                 if (pos > sizeof(buf))
  45                         goto truncate;
  46         } END_FOR_EACH_PTR(tmp);
  47         snprintf(buf + pos, sizeof(buf) - pos, ")");
  48
  49         return buf;
  50
  51 truncate:
  52         for (i = 0; i < 3; i++)
  53                 buf[sizeof(buf) - 2 - i] = '.';
  54         return buf;
  55 }
  56
  57 void __print_slist(struct state_list *slist)
  58 {
  59         struct sm_state *sm;
  60
  61         printf("dumping slist at %d\n", get_lineno());
  62         FOR_EACH_PTR(slist, sm) {
  63                 printf("%s\n", show_sm(sm));
  64         } END_FOR_EACH_PTR(sm);
  65         printf("---\n");
  66 }
  67
  68 /* NULL states go at the end to simplify merge_slist */
  69 int cmp_tracker(const struct sm_state *a, const struct sm_state *b)
  70 {
  71         int ret;
  72
  73         if (a == b)
  74                 return 0;
  75         if (!b)
  76                 return -1;
  77         if (!a)
  78                 return 1;
  79
  80         if (a->owner > b->owner)
  81                 return -1;
  82         if (a->owner < b->owner)
  83                 return 1;
  84
  85         ret = strcmp(a->name, b->name);
  86         if (ret)
  87                 return ret;
  88
  89         if (!b->sym && a->sym)
  90                 return -1;
  91         if (!a->sym && b->sym)
  92                 return 1;
  93         if (a->sym > b->sym)
  94                 return -1;
  95         if (a->sym < b->sym)
  96                 return 1;
  97
  98         return 0;
  99 }
 100
 101 static int cmp_sm_states(const struct sm_state *a, const struct sm_state *b)
 102 {
 103         int ret;
 104
 105         ret = cmp_tracker(a, b);
 106         if (ret)
 107                 return ret;
 108
 109         /* todo:  add hook for smatch_extra.c */
 110         if (a->state > b->state)
 111                 return -1;
 112         if (a->state < b->state)
 113                 return 1;
 114         return 0;
 115 }
 116
 117 static struct sm_state *alloc_sm_state(int owner, const char *name,
 118                              struct symbol *sym, struct smatch_state *state)
 119 {
 120         struct sm_state *sm_state = __alloc_sm_state(0);
 121
 122         sm_state_counter++;
 123
 124         sm_state->name = alloc_sname(name);
 125         sm_state->owner = owner;
 126         sm_state->sym = sym;
 127         sm_state->state = state;
 128         sm_state->line = get_lineno();
 129         sm_state->merged = 0;
 130         sm_state->implied = 0;
 131         sm_state->pool = NULL;
 132         sm_state->left = NULL;
 133         sm_state->right = NULL;
 134         sm_state->nr_children = 1;
 135         sm_state->possible = NULL;
 136         add_ptr_list(&sm_state->possible, sm_state);
 137         return sm_state;
 138 }
 139
 140 static struct sm_state *alloc_state_no_name(int owner, const char *name,
 141                                      struct symbol *sym,
 142                                      struct smatch_state *state)
 143 {
 144         struct sm_state *tmp;
 145
 146         tmp = alloc_sm_state(owner, NULL, sym, state);
 147         tmp->name = name;
 148         return tmp;
 149 }
 150
 151 void add_sm_state_slist(struct state_list **slist, struct sm_state *new)
 152 {
 153         struct sm_state *tmp;
 154
 155         FOR_EACH_PTR(*slist, tmp) {
 156                 if (cmp_sm_states(tmp, new) < 0)
 157                         continue;
 158                 else if (cmp_sm_states(tmp, new) == 0) {
 159                         return;
 160                 } else {
 161                         INSERT_CURRENT(new, tmp);
 162                         return;
 163                 }
 164         } END_FOR_EACH_PTR(tmp);
 165         add_ptr_list(slist, new);
 166 }
 167
 168 static void copy_possibles(struct sm_state *to, struct sm_state *from)
 169 {
 170         struct sm_state *tmp;
 171
 172         FOR_EACH_PTR(from->possible, tmp) {
 173                 add_sm_state_slist(&to->possible, tmp);
 174         } END_FOR_EACH_PTR(tmp);
 175 }
 176
 177 char *alloc_sname(const char *str)
 178 {
 179         char *tmp;
 180
 181         if (!str)
 182                 return NULL;
 183         tmp = __alloc_sname(strlen(str) + 1);
 184         strcpy(tmp, str);
 185         return tmp;
 186 }
 187
 188 int out_of_memory()
 189 {
 190         /*
 191          * I decided to use 50M here based on trial and error.
 192          * It works out OK for the kernel and so it should work
 193          * for most other projects as well.
 194          */
 195         if (sm_state_counter * sizeof(struct sm_state) >= 50000000)
 196                 return 1;
 197         return 0;
 198 }
 199
 200 static void free_sm_state(struct sm_state *sm)
 201 {
 202         free_slist(&sm->possible);
 203         /*
 204          * fixme.  Free the actual state.
 205          * Right now we leave it until the end of the function
 206          * because we don't want to double free it.
 207          * Use the freelist to not double free things
 208          */
 209 }
 210
 211 static void free_all_sm_states(struct allocation_blob *blob)
 212 {
 213         unsigned int size = sizeof(struct sm_state);
 214         unsigned int offset = 0;
 215
 216         while (offset < blob->offset) {
 217                 free_sm_state((struct sm_state *)(blob->data + offset));
 218                 offset += size;
 219         }
 220 }
 221
 222 /* At the end of every function we free all the sm_states */
 223 void free_every_single_sm_state(void)
 224 {
 225         struct allocator_struct *desc = &sm_state_allocator;
 226         struct allocation_blob *blob = desc->blobs;
 227
 228         desc->blobs = NULL;
 229         desc->allocations = 0;
 230         desc->total_bytes = 0;
 231         desc->useful_bytes = 0;
 232         desc->freelist = NULL;
 233         while (blob) {
 234                 struct allocation_blob *next = blob->next;
 235                 free_all_sm_states(blob);
 236                 blob_free(blob, desc->chunking);
 237                 blob = next;
 238         }
 239         clear_sname_alloc();
 240
 241         sm_state_counter = 0;
 242 }
 243
 244 struct sm_state *clone_sm(struct sm_state *s)
 245 {
 246         struct sm_state *ret;
 247
 248         ret = alloc_state_no_name(s->owner, s->name, s->sym, s->state);
 249         ret->merged = s->merged;
 250         ret->implied = s->implied;
 251         ret->line = s->line;
 252         /* clone_sm() doesn't copy the pools.  Each state needs to have
 253            only one pool. */
 254         ret->possible = clone_slist(s->possible);
 255         ret->left = s->left;
 256         ret->right = s->right;
 257         ret->nr_children = s->nr_children;
 258         return ret;
 259 }
 260
 261 int is_merged(struct sm_state *sm)
 262 {
 263         return sm->merged;
 264 }
 265
 266 int is_implied(struct sm_state *sm)
 267 {
 268         return sm->implied;
 269 }
 270
 271 int slist_has_state(struct state_list *slist, struct smatch_state *state)
 272 {
 273         struct sm_state *tmp;
 274
 275         FOR_EACH_PTR(slist, tmp) {
 276                 if (tmp->state == state)
 277                         return 1;
 278         } END_FOR_EACH_PTR(tmp);
 279         return 0;
 280 }
 281
 282 static void check_order(struct state_list *slist)
 283 {
 284 #ifdef CHECKORDER
 285         struct sm_state *sm;
 286         struct sm_state *last = NULL;
 287         int printed = 0;
 288
 289         FOR_EACH_PTR(slist, sm) {
 290                 if (last && cmp_tracker(sm, last) <= 0) {
 291                         printf("Error.  Unsorted slist %d vs %d, %p vs %p, "
 292                                "%s vs %s\n", last->owner, sm->owner,
 293                                last->sym, sm->sym, last->name, sm->name);
 294                         printed = 1;
 295                 }
 296                 last = state;
 297         } END_FOR_EACH_PTR(sm);
 298
 299         if (printed)
 300                 printf("======\n");
 301 #endif
 302 }
 303
 304 struct state_list *clone_slist(struct state_list *from_slist)
 305 {
 306         struct sm_state *sm;
 307         struct state_list *to_slist = NULL;
 308
 309         FOR_EACH_PTR(from_slist, sm) {
 310                 add_ptr_list(&to_slist, sm);
 311         } END_FOR_EACH_PTR(sm);
 312         check_order(to_slist);
 313         return to_slist;
 314 }
 315
 316 struct state_list_stack *clone_stack(struct state_list_stack *from_stack)
 317 {
 318         struct state_list *slist;
 319         struct state_list_stack *to_stack = NULL;
 320
 321         FOR_EACH_PTR(from_stack, slist) {
 322                 push_slist(&to_stack, slist);
 323         } END_FOR_EACH_PTR(slist);
 324         return to_stack;
 325 }
 326
 327 struct smatch_state *merge_states(int owner, const char *name,
 328                                   struct symbol *sym,
 329                                   struct smatch_state *state1,
 330                                   struct smatch_state *state2)
 331 {
 332         struct smatch_state *ret;
 333
 334         if (state1 == state2)
 335                 ret = state1;
 336         else if (__has_merge_function(owner))
 337                 ret = __client_merge_function(owner, state1, state2);
 338         else if (!state1 || !state2)
 339                 ret = &undefined;
 340         else
 341                 ret = &merged;
 342         return ret;
 343 }
 344
 345 struct sm_state *merge_sm_states(struct sm_state *one, struct sm_state *two)
 346 {
 347         struct smatch_state *s;
 348         struct sm_state *result;
 349
 350         if (one == two)
 351                 return one;
 352         s = merge_states(one->owner, one->name, one->sym, one->state, two->state);
 353         result = alloc_state_no_name(one->owner, one->name, one->sym, s);
 354         result->merged = 1;
 355         result->left = one;
 356         result->right = two;
 357         result->nr_children = one->nr_children + two->nr_children;
 358         copy_possibles(result, one);
 359         copy_possibles(result, two);
 360
 361         if (option_debug) {
 362                 struct sm_state *tmp;
 363                 int i = 0;
 364
 365                 printf("%d merge [%s] '%s' %s(L %d) + %s(L %d) => %s (",
 366                         get_lineno(), check_name(one->owner), one->name,
 367                         show_state(one->state), one->line,
 368                         show_state(two->state), two->line,
 369                         show_state(s));
 370
 371                 FOR_EACH_PTR(result->possible, tmp) {
 372                         if (i++)
 373                                 printf(", ");
 374                         printf("%s", show_state(tmp->state));
 375                 } END_FOR_EACH_PTR(tmp);
 376                 printf(")\n");
 377         }
 378
 379         return result;
 380 }
 381
 382 struct sm_state *get_sm_state_slist(struct state_list *slist, int owner, const char *name,
 383                                 struct symbol *sym)
 384 {
 385         struct sm_state *sm;
 386
 387         if (!name)
 388                 return NULL;
 389
 390         FOR_EACH_PTR(slist, sm) {
 391                 if (sm->owner == owner && sm->sym == sym && !strcmp(sm->name, name))
 392                         return sm;
 393         } END_FOR_EACH_PTR(sm);
 394         return NULL;
 395 }
 396
 397 struct smatch_state *get_state_slist(struct state_list *slist,
 398                                 int owner, const char *name,
 399                                 struct symbol *sym)
 400 {
 401         struct sm_state *sm;
 402
 403         sm = get_sm_state_slist(slist, owner, name, sym);
 404         if (sm)
 405                 return sm->state;
 406         return NULL;
 407 }
 408
 409 void overwrite_sm_state(struct state_list **slist, struct sm_state *new)
 410 {
 411         struct sm_state *tmp;
 412
 413         FOR_EACH_PTR(*slist, tmp) {
 414                 if (cmp_tracker(tmp, new) < 0)
 415                         continue;
 416                 else if (cmp_tracker(tmp, new) == 0) {
 417                         REPLACE_CURRENT_PTR(tmp, new);
 418                         return;
 419                 } else {
 420                         INSERT_CURRENT(new, tmp);
 421                         return;
 422                 }
 423         } END_FOR_EACH_PTR(tmp);
 424         add_ptr_list(slist, new);
 425 }
 426
 427 void overwrite_sm_state_stack(struct state_list_stack **stack,
 428                         struct sm_state *sm)
 429 {
 430         struct state_list *slist;
 431
 432         slist = pop_slist(stack);
 433         overwrite_sm_state(&slist, sm);
 434         push_slist(stack, slist);
 435 }
 436
 437 struct sm_state *set_state_slist(struct state_list **slist, int owner, const char *name,
 438                      struct symbol *sym, struct smatch_state *state)
 439 {
 440         struct sm_state *tmp;
 441         struct sm_state *new = alloc_sm_state(owner, name, sym, state);
 442
 443         FOR_EACH_PTR(*slist, tmp) {
 444                 if (cmp_tracker(tmp, new) < 0)
 445                         continue;
 446                 else if (cmp_tracker(tmp, new) == 0) {
 447                         REPLACE_CURRENT_PTR(tmp, new);
 448                         return new;
 449                 } else {
 450                         INSERT_CURRENT(new, tmp);
 451                         return new;
 452                 }
 453         } END_FOR_EACH_PTR(tmp);
 454         add_ptr_list(slist, new);
 455         return new;
 456 }
 457
 458 void delete_state_slist(struct state_list **slist, int owner, const char *name,
 459                         struct symbol *sym)
 460 {
 461         struct sm_state *sm;
 462
 463         FOR_EACH_PTR(*slist, sm) {
 464                 if (sm->owner == owner && sm->sym == sym && !strcmp(sm->name, name)) {
 465                         DELETE_CURRENT_PTR(sm);
 466                         return;
 467                 }
 468         } END_FOR_EACH_PTR(sm);
 469 }
 470
 471 void delete_state_stack(struct state_list_stack **stack, int owner, const char *name,
 472                         struct symbol *sym)
 473 {
 474         struct state_list *slist;
 475
 476         slist = pop_slist(stack);
 477         delete_state_slist(&slist, owner, name, sym);
 478         push_slist(stack, slist);
 479 }
 480
 481 void push_slist(struct state_list_stack **list_stack, struct state_list *slist)
 482 {
 483         add_ptr_list(list_stack, slist);
 484 }
 485
 486 struct state_list *pop_slist(struct state_list_stack **list_stack)
 487 {
 488         struct state_list *slist;
 489
 490         slist = last_ptr_list((struct ptr_list *)*list_stack);
 491         delete_ptr_list_last((struct ptr_list **)list_stack);
 492         return slist;
 493 }
 494
 495 void free_slist(struct state_list **slist)
 496 {
 497         __free_ptr_list((struct ptr_list **)slist);
 498 }
 499
 500 void free_stack(struct state_list_stack **stack)
 501 {
 502         __free_ptr_list((struct ptr_list **)stack);
 503 }
 504
 505 void free_stack_and_slists(struct state_list_stack **slist_stack)
 506 {
 507         struct state_list *slist;
 508
 509         FOR_EACH_PTR(*slist_stack, slist) {
 510                 free_slist(&slist);
 511         } END_FOR_EACH_PTR(slist);
 512         free_stack(slist_stack);
 513 }
 514
 515 /*
 516  * set_state_stack() sets the state for the top slist on the stack.
 517  */
 518 struct sm_state *set_state_stack(struct state_list_stack **stack, int owner, const char *name,
 519                                 struct symbol *sym, struct smatch_state *state)
 520 {
 521         struct state_list *slist;
 522         struct sm_state *sm;
 523
 524         slist = pop_slist(stack);
 525         sm = set_state_slist(&slist, owner, name, sym, state);
 526         push_slist(stack, slist);
 527
 528         return sm;
 529 }
 530
 531 /*
 532  * get_sm_state_stack() gets the state for the top slist on the stack.
 533  */
 534 struct sm_state *get_sm_state_stack(struct state_list_stack *stack,
 535                                 int owner, const char *name,
 536                                 struct symbol *sym)
 537 {
 538         struct state_list *slist;
 539         struct sm_state *ret;
 540
 541         slist = pop_slist(&stack);
 542         ret = get_sm_state_slist(slist, owner, name, sym);
 543         push_slist(&stack, slist);
 544         return ret;
 545 }
 546
 547 struct smatch_state *get_state_stack(struct state_list_stack *stack,
 548                                 int owner, const char *name,
 549                                 struct symbol *sym)
 550 {
 551         struct sm_state *sm;
 552
 553         sm = get_sm_state_stack(stack, owner, name, sym);
 554         if (sm)
 555                 return sm->state;
 556         return NULL;
 557 }
 558
 559 static void match_states(struct state_list **one, struct state_list **two)
 560 {
 561         struct sm_state *one_sm;
 562         struct sm_state *two_sm;
 563         struct sm_state *tmp;
 564         struct smatch_state *tmp_state;
 565         struct state_list *add_to_one = NULL;
 566         struct state_list *add_to_two = NULL;
 567
 568         PREPARE_PTR_LIST(*one, one_sm);
 569         PREPARE_PTR_LIST(*two, two_sm);
 570         for (;;) {
 571                 if (!one_sm && !two_sm)
 572                         break;
 573                 if (cmp_tracker(one_sm, two_sm) < 0) {
 574                         tmp_state = __client_unmatched_state_function(one_sm);
 575                         tmp = alloc_state_no_name(one_sm->owner, one_sm->name,
 576                                                   one_sm->sym, tmp_state);
 577                         add_ptr_list(&add_to_two, tmp);
 578                         NEXT_PTR_LIST(one_sm);
 579                 } else if (cmp_tracker(one_sm, two_sm) == 0) {
 580                         NEXT_PTR_LIST(one_sm);
 581                         NEXT_PTR_LIST(two_sm);
 582                 } else {
 583                         tmp_state = __client_unmatched_state_function(two_sm);
 584                         tmp = alloc_state_no_name(two_sm->owner, two_sm->name,
 585                                                   two_sm->sym, tmp_state);
 586                         add_ptr_list(&add_to_one, tmp);
 587                         NEXT_PTR_LIST(two_sm);
 588                 }
 589         }
 590         FINISH_PTR_LIST(two_sm);
 591         FINISH_PTR_LIST(one_sm);
 592
 593         overwrite_slist(add_to_one, one);
 594         overwrite_slist(add_to_two, two);
 595 }
 596
 597 static void clone_pool_havers(struct state_list *slist)
 598 {
 599         struct sm_state *sm;
 600         struct sm_state *new;
 601
 602         FOR_EACH_PTR(slist, sm) {
 603                 if (sm->pool) {
 604                         new = clone_sm(sm);
 605                         REPLACE_CURRENT_PTR(sm, new);
 606                 }
 607         } END_FOR_EACH_PTR(sm);
 608 }
 609
 610 int __slist_id;
 611 /*
 612  * Sets the first state to the slist_id.
 613  */
 614 static void set_slist_id(struct state_list *slist)
 615 {
 616         struct smatch_state *state;
 617         struct sm_state *tmp, *new;
 618
 619         state = alloc_state_num(++__slist_id);
 620         new = alloc_sm_state(-1, "unnull_path", NULL, state);
 621
 622         FOR_EACH_PTR(slist, tmp) {
 623                 if (tmp->owner != (unsigned short)-1)
 624                         return;
 625                 REPLACE_CURRENT_PTR(tmp, new);
 626                 return;
 627         } END_FOR_EACH_PTR(tmp);
 628 }
 629
 630 int get_slist_id(struct state_list *slist)
 631 {
 632         struct sm_state *tmp;
 633
 634         FOR_EACH_PTR(slist, tmp) {
 635                 if (tmp->owner != (unsigned short)-1)
 636                         return 0;
 637                 return PTR_INT(tmp->state->data);
 638         } END_FOR_EACH_PTR(tmp);
 639         return 0;
 640 }
 641
 642 /*
 643  * merge_slist() is called whenever paths merge, such as after
 644  * an if statement.  It takes the two slists and creates one.
 645  */
 646 void merge_slist(struct state_list **to, struct state_list *slist)
 647 {
 648         struct sm_state *one_sm, *two_sm, *tmp;
 649         struct state_list *results = NULL;
 650         struct state_list *implied_one = NULL;
 651         struct state_list *implied_two = NULL;
 652
 653         if (out_of_memory())
 654                 return;
 655
 656         check_order(*to);
 657         check_order(slist);
 658
 659         /* merging a null and nonnull path gives you only the nonnull path */
 660         if (!slist)
 661                 return;
 662
 663         if (!*to) {
 664                 *to = clone_slist(slist);
 665                 return;
 666         }
 667
 668         implied_one = clone_slist(*to);
 669         implied_two = clone_slist(slist);
 670
 671         match_states(&implied_one, &implied_two);
 672
 673         clone_pool_havers(implied_one);
 674         clone_pool_havers(implied_two);
 675
 676         set_slist_id(implied_one);
 677         set_slist_id(implied_two);
 678
 679         PREPARE_PTR_LIST(implied_one, one_sm);
 680         PREPARE_PTR_LIST(implied_two, two_sm);
 681         for (;;) {
 682                 if (!one_sm && !two_sm)
 683                         break;
 684                 if (cmp_tracker(one_sm, two_sm) < 0) {
 685                         sm_msg("error:  Internal smatch error.");
 686                         NEXT_PTR_LIST(one_sm);
 687                 } else if (cmp_tracker(one_sm, two_sm) == 0) {
 688                         if (one_sm != two_sm) {
 689                                 one_sm->pool = implied_one;
 690                                 two_sm->pool = implied_two;
 691                         }
 692
 693                         tmp = merge_sm_states(one_sm, two_sm);
 694                         add_ptr_list(&results, tmp);
 695                         NEXT_PTR_LIST(one_sm);
 696                         NEXT_PTR_LIST(two_sm);
 697                 } else {
 698                         sm_msg("error:  Internal smatch error.");
 699                         NEXT_PTR_LIST(two_sm);
 700                 }
 701         }
 702         FINISH_PTR_LIST(two_sm);
 703         FINISH_PTR_LIST(one_sm);
 704
 705         free_slist(to);
 706         *to = results;
 707 }
 708
 709 /*
 710  * filter_slist() removes any sm states "slist" holds in common with "filter"
 711  */
 712 void filter_slist(struct state_list **slist, struct state_list *filter)
 713 {
 714         struct sm_state *one_sm, *two_sm;
 715         struct state_list *results = NULL;
 716
 717         PREPARE_PTR_LIST(*slist, one_sm);
 718         PREPARE_PTR_LIST(filter, two_sm);
 719         for (;;) {
 720                 if (!one_sm && !two_sm)
 721                         break;
 722                 if (cmp_tracker(one_sm, two_sm) < 0) {
 723                         add_ptr_list(&results, one_sm);
 724                         NEXT_PTR_LIST(one_sm);
 725                 } else if (cmp_tracker(one_sm, two_sm) == 0) {
 726                         if (one_sm != two_sm)
 727                                 add_ptr_list(&results, one_sm);
 728                         NEXT_PTR_LIST(one_sm);
 729                         NEXT_PTR_LIST(two_sm);
 730                 } else {
 731                         NEXT_PTR_LIST(two_sm);
 732                 }
 733         }
 734         FINISH_PTR_LIST(two_sm);
 735         FINISH_PTR_LIST(one_sm);
 736
 737         free_slist(slist);
 738         *slist = results;
 739 }
 740
 741 /*
 742  * and_slist_stack() pops the top two slists, overwriting the one with
 743  * the other and pushing it back on the stack.
 744  */
 745 void and_slist_stack(struct state_list_stack **slist_stack)
 746 {
 747         struct sm_state *tmp;
 748         struct state_list *right_slist = pop_slist(slist_stack);
 749
 750         FOR_EACH_PTR(right_slist, tmp) {
 751                 overwrite_sm_state_stack(slist_stack, tmp);
 752         } END_FOR_EACH_PTR(tmp);
 753         free_slist(&right_slist);
 754 }
 755
 756 /*
 757  * or_slist_stack() is for if we have:  if (foo || bar) { foo->baz;
 758  * It pops the two slists from the top of the stack and merges them
 759  * together in a way that preserves the things they have in common
 760  * but creates a merged state for most of the rest.
 761  * You could have code that had:  if (foo || foo) { foo->baz;
 762  * It's this function which ensures smatch does the right thing.
 763  */
 764 void or_slist_stack(struct state_list_stack **pre_conds,
 765                     struct state_list *cur_slist,
 766                     struct state_list_stack **slist_stack)
 767 {
 768         struct state_list *new;
 769         struct state_list *old;
 770         struct state_list *pre_slist;
 771         struct state_list *res;
 772         struct state_list *tmp_slist;
 773
 774         new = pop_slist(slist_stack);
 775         old = pop_slist(slist_stack);
 776
 777         pre_slist = pop_slist(pre_conds);
 778         push_slist(pre_conds, clone_slist(pre_slist));
 779
 780         res = clone_slist(pre_slist);
 781         overwrite_slist(old, &res);
 782
 783         tmp_slist = clone_slist(cur_slist);
 784         overwrite_slist(new, &tmp_slist);
 785
 786         merge_slist(&res, tmp_slist);
 787         filter_slist(&res, pre_slist);
 788
 789         push_slist(slist_stack, res);
 790         free_slist(&tmp_slist);
 791         free_slist(&pre_slist);
 792         free_slist(&new);
 793         free_slist(&old);
 794 }
 795
 796 /*
 797  * get_slist_from_named_stack() is only used for gotos.
 798  */
 799 struct state_list **get_slist_from_named_stack(struct named_stack *stack,
 800                                               const char *name)
 801 {
 802         struct named_slist *tmp;
 803
 804         FOR_EACH_PTR(stack, tmp) {
 805                 if (!strcmp(tmp->name, name))
 806                         return &tmp->slist;
 807         } END_FOR_EACH_PTR(tmp);
 808         return NULL;
 809 }
 810
 811 void overwrite_slist(struct state_list *from, struct state_list **to)
 812 {
 813         struct sm_state *tmp;
 814
 815         FOR_EACH_PTR(from, tmp) {
 816                 overwrite_sm_state(to, tmp);
 817         } END_FOR_EACH_PTR(tmp);
 818 }