smatch_extra.c

   1 /*
   2  * sparse/smatch_extra.c
   3  *
   4  * Copyright (C) 2008 Dan Carpenter.
   5  *
   6  * Licensed under the Open Software License version 1.1
   7  *
   8  */
   9
  10 /*
  11  * smatch_extra.c is supposed to track the value of every variable.
  12  */
  13
  14 #include <stdlib.h>
  15 #ifndef __USE_ISOC99
  16 #define __USE_ISOC99
  17 #endif
  18 #include <limits.h>
  19 #include "parse.h"
  20 #include "smatch.h"
  21 #include "smatch_slist.h"
  22 #include "smatch_extra.h"
  23
  24 static int my_id;
  25
  26 static struct symbol *cur_func;
  27
  28 struct data_range whole_range = {
  29         .min = LLONG_MIN,
  30         .max = LLONG_MAX,
  31 };
  32
  33 static struct data_info *alloc_dinfo(void)
  34 {
  35         struct data_info *ret;
  36
  37         ret = __alloc_data_info(0);
  38         ret->equiv = NULL;
  39         ret->type = DATA_RANGE;
  40         ret->value_ranges = NULL;
  41         return ret;
  42 }
  43
  44 static struct data_info *alloc_dinfo_range(long long min, long long max)
  45 {
  46         struct data_info *ret;
  47
  48         ret = alloc_dinfo();
  49         add_range(&ret->value_ranges, min, max);
  50         return ret;
  51 }
  52
  53 static struct data_info *alloc_dinfo_range_list(struct range_list *rl)
  54 {
  55         struct data_info *ret;
  56
  57         ret = alloc_dinfo();
  58         ret->value_ranges = rl;
  59         return ret;
  60 }
  61
  62 static struct data_info *clone_dinfo(struct data_info *dinfo)
  63 {
  64         struct data_info *ret;
  65
  66         ret = alloc_dinfo();
  67         ret->equiv = clone_tracker_list(dinfo->equiv);
  68         ret->value_ranges = clone_range_list(dinfo->value_ranges);
  69         return ret;
  70 }
  71
  72 static struct smatch_state *clone_extra_state(struct smatch_state *state)
  73 {
  74         struct smatch_state *ret;
  75
  76         ret = __alloc_smatch_state(0);
  77         ret->name = state->name;
  78         ret->data = clone_dinfo(get_dinfo(state));
  79         return ret;
  80 }
  81
  82 static struct smatch_state *alloc_extra_state_empty(void)
  83 {
  84         struct smatch_state *state;
  85         struct data_info *dinfo;
  86
  87         dinfo = alloc_dinfo();
  88         state = __alloc_smatch_state(0);
  89         state->data = dinfo;
  90         state->name = "";
  91         return state;
  92 }
  93
  94 static struct smatch_state *alloc_extra_state_no_name(int val)
  95 {
  96         struct smatch_state *state;
  97
  98         state = __alloc_smatch_state(0);
  99         state->data = (void *)alloc_dinfo_range(val, val);
 100         return state;
 101 }
 102
 103 /* We do this because ->value_ranges is a list */
 104 struct smatch_state *extra_undefined(void)
 105 {
 106         struct data_info *dinfo;
 107         static struct smatch_state *ret;
 108         static struct symbol *prev_func;
 109
 110         if  (prev_func == cur_func)
 111                 return ret;
 112         prev_func = cur_func;
 113
 114         dinfo = alloc_dinfo_range(whole_range.min, whole_range.max);
 115         ret = __alloc_smatch_state(0);
 116         ret->name = "unknown";
 117         ret->data = dinfo;
 118         return ret;
 119 }
 120
 121 struct smatch_state *alloc_extra_state(long long val)
 122 {
 123         struct smatch_state *state;
 124
 125         state = alloc_extra_state_no_name(val);
 126         state->name = show_ranges(get_dinfo(state)->value_ranges);
 127         return state;
 128 }
 129
 130 struct smatch_state *alloc_extra_state_range(long long min, long long max)
 131 {
 132         struct smatch_state *state;
 133
 134         if (min == whole_range.min && max == whole_range.max)
 135                 return extra_undefined();
 136         state = __alloc_smatch_state(0);
 137         state->data = (void *)alloc_dinfo_range(min, max);
 138         state->name = show_ranges(get_dinfo(state)->value_ranges);
 139         return state;
 140 }
 141
 142 struct smatch_state *alloc_extra_state_range_list(struct range_list *rl)
 143 {
 144         struct smatch_state *state;
 145
 146         state = __alloc_smatch_state(0);
 147         state->data = (void *)alloc_dinfo_range_list(rl);
 148         state->name = show_ranges(get_dinfo(state)->value_ranges);
 149         return state;
 150 }
 151
 152 static void add_equiv(struct smatch_state *state, const char *name, struct symbol *sym)
 153 {
 154         struct data_info *dinfo;
 155
 156         dinfo = get_dinfo(state);
 157         add_tracker(&dinfo->equiv, SMATCH_EXTRA, name, sym);
 158 }
 159
 160 static void del_equiv(struct smatch_state *state, const char *name, struct symbol *sym)
 161 {
 162         struct data_info *dinfo;
 163
 164         dinfo = get_dinfo(state);
 165         del_tracker(&dinfo->equiv, SMATCH_EXTRA, name, sym);
 166 }
 167
 168 static void remove_from_equiv(const char *name, struct symbol *sym)
 169 {
 170         struct sm_state *orig_sm;
 171         struct tracker *tracker;
 172         struct smatch_state *state;
 173
 174         orig_sm = get_sm_state(SMATCH_EXTRA, name, sym);
 175         if (!orig_sm || !get_dinfo(orig_sm->state)->equiv)
 176                 return;
 177
 178         state = clone_extra_state(orig_sm->state);
 179         del_equiv(state, name, sym);
 180
 181         FOR_EACH_PTR(get_dinfo(orig_sm->state)->equiv, tracker) {
 182                 struct sm_state *new_sm;
 183
 184                 new_sm = clone_sm(orig_sm);
 185                 new_sm->name = tracker->name;
 186                 new_sm->sym = tracker->sym;
 187                 new_sm->state = state;
 188                 __set_sm(new_sm);
 189         } END_FOR_EACH_PTR(tracker);
 190 }
 191
 192 static void remove_from_equiv_expr(struct expression *expr)
 193 {
 194         char *name;
 195         struct symbol *sym;
 196
 197         name = get_variable_from_expr(expr, &sym);
 198         if (!name || !sym)
 199                 goto free;
 200         remove_from_equiv(name, sym);
 201 free:
 202         free_string(name);
 203 }
 204
 205 struct sm_state *set_extra_mod(const char *name, struct symbol *sym, struct smatch_state *state)
 206 {
 207         remove_from_equiv(name, sym);
 208         return set_state(SMATCH_EXTRA, name, sym, state);
 209 }
 210
 211 struct sm_state *set_extra_expr_mod(struct expression *expr, struct smatch_state *state)
 212 {
 213         remove_from_equiv_expr(expr);
 214         return set_state_expr(SMATCH_EXTRA, expr, state);
 215 }
 216
 217 void set_extra_true_false(const char *name, struct symbol *sym,
 218                         struct smatch_state *true_state,
 219                         struct smatch_state *false_state)
 220 {
 221         struct tracker *tracker;
 222         struct smatch_state *orig_state;
 223
 224         orig_state = get_state(SMATCH_EXTRA, name, sym);
 225
 226         if (!orig_state || !get_dinfo(orig_state)->equiv) {
 227                 set_true_false_states(SMATCH_EXTRA, name, sym, true_state, false_state);
 228                 return;
 229         }
 230
 231         FOR_EACH_PTR(get_dinfo(orig_state)->equiv, tracker) {
 232                 set_true_false_states(tracker->owner, tracker->name, tracker->sym,
 233                                 true_state, false_state);
 234                 if (true_state)
 235                         add_equiv(true_state, tracker->name, tracker->sym);
 236                 if (false_state)
 237                         add_equiv(false_state, tracker->name, tracker->sym);
 238         } END_FOR_EACH_PTR(tracker);
 239 }
 240
 241 struct data_info *get_dinfo(struct smatch_state *state)
 242 {
 243         if (!state)
 244                 return NULL;
 245         return (struct data_info *)state->data;
 246
 247 }
 248
 249 struct smatch_state *filter_range(struct smatch_state *orig,
 250                                  long long filter_min, long long filter_max)
 251 {
 252         struct smatch_state *ret;
 253         struct data_info *orig_info;
 254         struct data_info *ret_info;
 255
 256         if (!orig)
 257                 orig = extra_undefined();
 258         orig_info = get_dinfo(orig);
 259         ret = alloc_extra_state_empty();
 260         ret_info = get_dinfo(ret);
 261         ret_info->value_ranges = remove_range(orig_info->value_ranges, filter_min, filter_max);
 262         ret->name = show_ranges(ret_info->value_ranges);
 263         return ret;
 264 }
 265
 266 struct smatch_state *add_filter(struct smatch_state *orig, long long num)
 267 {
 268         return filter_range(orig, num, num);
 269 }
 270
 271 static struct smatch_state *merge_func(const char *name, struct symbol *sym,
 272                                        struct smatch_state *s1,
 273                                        struct smatch_state *s2)
 274 {
 275         struct data_info *info1 = get_dinfo(s1);
 276         struct data_info *info2 = get_dinfo(s2);
 277         struct data_info *ret_info;
 278         struct smatch_state *tmp;
 279         struct range_list *value_ranges;
 280         struct tracker *tracker;
 281
 282         value_ranges = range_list_union(info1->value_ranges, info2->value_ranges);
 283         tmp = alloc_extra_state_empty();
 284         ret_info = get_dinfo(tmp);
 285         ret_info->value_ranges = value_ranges;
 286         tmp->name = show_ranges(ret_info->value_ranges);
 287         FOR_EACH_PTR(info1->equiv, tracker) {
 288                 if (in_tracker_list(info2->equiv, tracker->owner, tracker->name, tracker->sym))
 289                         add_equiv(tmp, tracker->name, tracker->sym);
 290         } END_FOR_EACH_PTR(tracker);
 291         return tmp;
 292 }
 293
 294 static struct sm_state *handle_canonical_while_count_down(struct statement *loop)
 295 {
 296         struct expression *iter_var;
 297         struct expression *condition;
 298         struct sm_state *sm;
 299         long long start;
 300
 301         condition = strip_expr(loop->iterator_pre_condition);
 302         if (!condition)
 303                 return NULL;
 304         if (condition->type != EXPR_PREOP && condition->type != EXPR_POSTOP)
 305                 return NULL;
 306         if (condition->op != SPECIAL_DECREMENT)
 307                 return NULL;
 308
 309         iter_var = condition->unop;
 310         sm = get_sm_state_expr(SMATCH_EXTRA, iter_var);
 311         if (!sm)
 312                 return NULL;
 313         if (get_dinfo_min(get_dinfo(sm->state)) < 0)
 314                 return NULL;
 315         start = get_dinfo_max(get_dinfo(sm->state));
 316         if  (start <= 0)
 317                 return NULL;
 318         if (start != whole_range.max)
 319                 start--;
 320
 321         if (condition->type == EXPR_PREOP)
 322                 set_extra_expr_mod(iter_var, alloc_extra_state_range(1, start));
 323         if (condition->type == EXPR_POSTOP)
 324                 set_extra_expr_mod(iter_var, alloc_extra_state_range(0, start));
 325         return get_sm_state_expr(SMATCH_EXTRA, iter_var);
 326 }
 327
 328 static struct sm_state *handle_canonical_for_loops(struct statement *loop)
 329 {
 330         struct expression *iter_expr;
 331         struct expression *iter_var;
 332         struct expression *condition;
 333         struct sm_state *sm;
 334         long long start;
 335         long long end;
 336
 337         if (!loop->iterator_post_statement)
 338                 return NULL;
 339         if (loop->iterator_post_statement->type != STMT_EXPRESSION)
 340                 return NULL;
 341         iter_expr = loop->iterator_post_statement->expression;
 342         if (!loop->iterator_pre_condition)
 343                 return NULL;
 344         if (loop->iterator_pre_condition->type != EXPR_COMPARE)
 345                 return NULL;
 346         condition = loop->iterator_pre_condition;
 347
 348
 349         if (iter_expr->op != SPECIAL_INCREMENT)
 350                 return NULL;
 351         iter_var = iter_expr->unop;
 352         sm = get_sm_state_expr(SMATCH_EXTRA, iter_var);
 353         if (!sm)
 354                 return NULL;
 355         if (!get_single_value_from_dinfo(get_dinfo(sm->state), &start))
 356                 return NULL;
 357         if (!get_implied_value(condition->right, &end))
 358                 end = whole_range.max;
 359         if (get_sm_state_expr(SMATCH_EXTRA, condition->left) != sm)
 360                 return NULL;
 361
 362         switch (condition->op) {
 363         case SPECIAL_NOTEQUAL:
 364         case '<':
 365                 if (end != whole_range.max)
 366                         end--;
 367                 break;
 368         case SPECIAL_LTE:
 369                 break;
 370         default:
 371                 return NULL;
 372         }
 373         if (end < start)
 374                 return NULL;
 375         set_extra_expr_mod(iter_var, alloc_extra_state_range(start, end));
 376         return get_sm_state_expr(SMATCH_EXTRA, iter_var);
 377 }
 378
 379 struct sm_state *__extra_handle_canonical_loops(struct statement *loop, struct state_list **slist)
 380 {
 381         struct sm_state *ret;
 382
 383         __push_fake_cur_slist();;
 384         if (!loop->iterator_post_statement)
 385                 ret = handle_canonical_while_count_down(loop);
 386         else
 387                 ret = handle_canonical_for_loops(loop);
 388         *slist = __pop_fake_cur_slist();
 389         return ret;
 390 }
 391
 392 int __iterator_unchanged(struct sm_state *sm)
 393 {
 394         if (!sm)
 395                 return 0;
 396         if (get_sm_state(my_id, sm->name, sm->sym) == sm)
 397                 return 1;
 398         return 0;
 399 }
 400
 401 static void while_count_down_after(struct sm_state *sm, struct expression *condition)
 402 {
 403         long long after_value;
 404
 405         /* paranoid checking.  prolly not needed */
 406         condition = strip_expr(condition);
 407         if (!condition)
 408                 return;
 409         if (condition->type != EXPR_PREOP && condition->type != EXPR_POSTOP)
 410                 return;
 411         if (condition->op != SPECIAL_DECREMENT)
 412                 return;
 413         after_value = get_dinfo_min(get_dinfo(sm->state));
 414         after_value--;
 415         set_extra_mod(sm->name, sm->sym, alloc_extra_state(after_value));
 416 }
 417
 418 void __extra_pre_loop_hook_after(struct sm_state *sm,
 419                                 struct statement *iterator,
 420                                 struct expression *condition)
 421 {
 422         struct expression *iter_expr;
 423         char *name;
 424         struct symbol *sym;
 425         long long value;
 426         int left = 0;
 427         struct smatch_state *state;
 428         struct data_info *dinfo;
 429         long long min, max;
 430
 431         if (!iterator) {
 432                 while_count_down_after(sm, condition);
 433                 return;
 434         }
 435
 436         iter_expr = iterator->expression;
 437
 438         if (condition->type != EXPR_COMPARE)
 439                 return;
 440         if (!get_value(condition->left, &value)) {
 441                 if (!get_value(condition->right, &value))
 442                         return;
 443                 left = 1;
 444         }
 445         if (left)
 446                 name = get_variable_from_expr(condition->left, &sym);
 447         else
 448                 name = get_variable_from_expr(condition->right, &sym);
 449         if (!name || !sym)
 450                 goto free;
 451         if (sym != sm->sym || strcmp(name, sm->name))
 452                 goto free;
 453         state = get_state(my_id, name, sym);
 454         dinfo = get_dinfo(state);
 455         min = get_dinfo_min(dinfo);
 456         max = get_dinfo_max(dinfo);
 457         if (iter_expr->op == SPECIAL_INCREMENT && min != whole_range.min && max == whole_range.max) {
 458                 set_extra_mod(name, sym, alloc_extra_state(min));
 459         } else if (min == whole_range.min && max != whole_range.max) {
 460                 set_extra_mod(name, sym, alloc_extra_state(max));
 461         }
 462 free:
 463         free_string(name);
 464         return;
 465 }
 466
 467 static struct smatch_state *unmatched_state(struct sm_state *sm)
 468 {
 469         return extra_undefined();
 470 }
 471
 472 static void match_function_call(struct expression *expr)
 473 {
 474         struct expression *tmp;
 475         struct symbol *sym;
 476         char *name;
 477         int i = 0;
 478
 479         FOR_EACH_PTR(expr->args, tmp) {
 480                 if (tmp->type == EXPR_PREOP && tmp->op == '&') {
 481                         name = get_variable_from_expr(tmp->unop, &sym);
 482                         if (name) {
 483                                 set_extra_mod(name, sym, extra_undefined());
 484                         }
 485                         free_string(name);
 486                 }
 487                 i++;
 488         } END_FOR_EACH_PTR(tmp);
 489 }
 490
 491 static void set_equiv(struct sm_state *right_sm, struct expression *left)
 492 {
 493         struct smatch_state *state;
 494         struct data_info *dinfo;
 495         struct tracker *tracker;
 496         char *name;
 497         struct symbol *sym;
 498
 499         name = get_variable_from_expr(left, &sym);
 500         if (!name || !sym)
 501                 goto free;
 502
 503         state = clone_extra_state(right_sm->state);
 504
 505         dinfo = get_dinfo(state);
 506         if (!dinfo->equiv)
 507                 add_equiv(state, right_sm->name, right_sm->sym);
 508         add_equiv(state, name, sym);
 509
 510         FOR_EACH_PTR(dinfo->equiv, tracker) {
 511                 struct sm_state *new_sm;
 512
 513                 new_sm = clone_sm(right_sm);
 514                 new_sm->name = tracker->name;
 515                 new_sm->sym = tracker->sym;
 516                 new_sm->state = state;
 517                 __set_sm(new_sm);
 518         } END_FOR_EACH_PTR(tracker);
 519 free:
 520         free_string(name);
 521 }
 522
 523 static void match_assign(struct expression *expr)
 524 {
 525         struct expression *left;
 526         struct expression *right;
 527         struct sm_state *right_sm;
 528         struct symbol *sym;
 529         char *name;
 530         long long value;
 531         int known;
 532         long long min = whole_range.min;
 533         long long max = whole_range.max;
 534         long long tmp;
 535         struct range_list *rl = NULL;
 536
 537         left = strip_expr(expr->left);
 538         name = get_variable_from_expr(left, &sym);
 539         if (!name)
 540                 return;
 541         right = strip_expr(expr->right);
 542         while (right->type == EXPR_ASSIGNMENT && right->op == '=')
 543                 right = strip_expr(right->left);
 544
 545         right_sm = get_sm_state_expr(SMATCH_EXTRA, right);
 546         if (expr->op == '=' && right_sm) {
 547                 set_equiv(right_sm, left);
 548                 goto free;
 549         }
 550
 551         known = get_implied_range_list(right, &rl);
 552         if (expr->op == '=') {
 553                 if (known)
 554                         set_extra_mod(name, sym, alloc_extra_state_range_list(rl));
 555                 else
 556                         set_extra_mod(name, sym, extra_undefined());
 557                 goto free;
 558         }
 559
 560         known = get_implied_value(right, &value);
 561         if (expr->op == SPECIAL_ADD_ASSIGN) {
 562                 if (get_implied_min(left, &tmp)) {
 563                         if (known)
 564                                 min = tmp + value;
 565                         else
 566                                 min = tmp;
 567                 }
 568
 569         }
 570         if (expr->op == SPECIAL_SUB_ASSIGN) {
 571                 if (get_implied_max(left, &tmp)) {
 572                         if (known)
 573                                 max = tmp - value;
 574                         else
 575                                 max = tmp;
 576                 }
 577
 578         }
 579         set_extra_mod(name, sym, alloc_extra_state_range(min, max));
 580 free:
 581         free_string(name);
 582 }
 583
 584 static void unop_expr(struct expression *expr)
 585 {
 586         struct symbol *sym;
 587         char *name;
 588         long long min = whole_range.min;
 589         long long max = whole_range.max;
 590         long long val;
 591
 592         if (expr->op == '*')
 593                 return;
 594         if (expr->op == '(')
 595                 return;
 596         if (expr->op == '!')
 597                 return;
 598
 599         name = get_variable_from_expr(expr->unop, &sym);
 600         if (!name)
 601                 goto free;
 602         if (expr->op == SPECIAL_INCREMENT) {
 603                 if (get_implied_min(expr->unop, &val))
 604                         min = val + 1;
 605         }
 606         if (expr->op == SPECIAL_DECREMENT) {
 607                 if (get_implied_max(expr->unop, &val))
 608                         max = val - 1;
 609         }
 610         set_extra_mod(name, sym, alloc_extra_state_range(min, max));
 611 free:
 612         free_string(name);
 613 }
 614
 615 static void delete_state_tracker(struct tracker *t)
 616 {
 617         remove_from_equiv(t->name, t->sym);
 618         delete_state(t->owner, t->name, t->sym);
 619 }
 620
 621 static void scoped_state_extra(const char *name, struct symbol *sym)
 622 {
 623         struct tracker *t;
 624
 625         t = alloc_tracker(SMATCH_EXTRA, name, sym);
 626         add_scope_hook((scope_hook *)&delete_state_tracker, t);
 627 }
 628
 629 static void match_declarations(struct symbol *sym)
 630 {
 631         const char *name;
 632         long long val;
 633
 634         if (sym->ident) {
 635                 name = sym->ident->name;
 636                 if (sym->initializer) {
 637                         if (get_value(sym->initializer, &val))
 638                                 set_state(SMATCH_EXTRA, name, sym, alloc_extra_state(val));
 639                         else
 640                                 set_state(SMATCH_EXTRA, name, sym, extra_undefined());
 641                         scoped_state_extra(name, sym);
 642                 } else {
 643                         set_state(SMATCH_EXTRA, name, sym, extra_undefined());
 644                         scoped_state_extra(name, sym);
 645                 }
 646         }
 647 }
 648
 649 static void match_function_def(struct symbol *sym)
 650 {
 651         struct symbol *arg;
 652
 653         cur_func = sym;
 654         FOR_EACH_PTR(sym->ctype.base_type->arguments, arg) {
 655                 if (!arg->ident) {
 656                         continue;
 657                 }
 658                 set_state(my_id, arg->ident->name, arg, extra_undefined());
 659         } END_FOR_EACH_PTR(arg);
 660 }
 661
 662 static int last_stmt_val(struct statement *stmt, long long *val)
 663 {
 664         struct expression *expr;
 665
 666         if (!stmt)
 667                 return 0;
 668
 669         stmt = last_ptr_list((struct ptr_list *)stmt->stmts);
 670         if (stmt->type != STMT_EXPRESSION)
 671                 return 0;
 672         expr = stmt->expression;
 673         return get_value(expr, val);
 674 }
 675
 676 static void match_comparison(struct expression *expr)
 677 {
 678         long long fixed;
 679         char *name = NULL;
 680         struct symbol *sym;
 681         struct smatch_state *true_state;
 682         struct smatch_state *false_state;
 683         struct smatch_state *orig;
 684         int left = 0;
 685         int comparison = expr->op;
 686         struct expression *varies = expr->right;
 687
 688         if (!get_value(expr->left, &fixed)) {
 689                 if (!get_value(expr->right, &fixed))
 690                         return;
 691                 varies = strip_expr(expr->left);
 692                 left = 1;
 693         }
 694         if (varies->op == SPECIAL_INCREMENT || varies->op == SPECIAL_DECREMENT)
 695                 varies = varies->unop;
 696         if (varies->type == EXPR_CALL) {
 697                 function_comparison(comparison, varies, fixed, left);
 698                 return;
 699         }
 700
 701         name = get_variable_from_expr(varies, &sym);
 702         if (!name || !sym)
 703                 goto free;
 704
 705         orig = get_state(my_id, name, sym);
 706         if (!orig)
 707                 orig = extra_undefined();
 708
 709         switch (comparison) {
 710         case '<':
 711         case SPECIAL_UNSIGNED_LT:
 712                 if (left) {
 713                         true_state = filter_range(orig, fixed, whole_range.max);
 714                         false_state = filter_range(orig, whole_range.min, fixed - 1);
 715                 } else {
 716                         true_state = filter_range(orig, whole_range.min, fixed);
 717                         false_state = filter_range(orig, fixed + 1, whole_range.max);
 718                 }
 719                 break;
 720         case SPECIAL_UNSIGNED_LTE:
 721         case SPECIAL_LTE:
 722                 if (left) {
 723                         true_state = filter_range(orig, fixed + 1, whole_range.max);
 724                         false_state = filter_range(orig, whole_range.min, fixed);
 725                 } else {
 726                         true_state = filter_range(orig, whole_range.min, fixed - 1);
 727                         false_state = filter_range(orig, fixed, whole_range.max);
 728                 }
 729                 break;
 730         case SPECIAL_EQUAL:
 731                 if (possibly_true(SPECIAL_EQUAL, get_dinfo(orig), fixed, fixed))
 732                         true_state = alloc_extra_state(fixed);
 733                 else
 734                         true_state = alloc_extra_state_empty();
 735                 false_state = filter_range(orig, fixed, fixed);
 736                 break;
 737         case SPECIAL_UNSIGNED_GTE:
 738         case SPECIAL_GTE:
 739                 if (left) {
 740                         true_state = filter_range(orig, whole_range.min, fixed - 1);
 741                         false_state = filter_range(orig, fixed, whole_range.max);
 742                 } else {
 743                         true_state = filter_range(orig, fixed + 1, whole_range.max);
 744                         false_state = filter_range(orig, whole_range.min, fixed);
 745                 }
 746                 break;
 747         case '>':
 748         case SPECIAL_UNSIGNED_GT:
 749                 if (left) {
 750                         true_state = filter_range(orig, whole_range.min, fixed);
 751                         false_state = filter_range(orig, fixed + 1, whole_range.max);
 752                 } else {
 753                         true_state = filter_range(orig, fixed, whole_range.max);
 754                         false_state = filter_range(orig, whole_range.min, fixed - 1);
 755                 }
 756                 break;
 757         case SPECIAL_NOTEQUAL:
 758                 true_state = filter_range(orig, fixed, fixed);
 759                 if (possibly_true(SPECIAL_EQUAL, get_dinfo(orig), fixed, fixed))
 760                         false_state = alloc_extra_state(fixed);
 761                 else
 762                         false_state = alloc_extra_state_empty();
 763                 break;
 764         default:
 765                 sm_msg("unhandled comparison %d\n", comparison);
 766                 goto free;
 767         }
 768         set_extra_true_false(name, sym, true_state, false_state);
 769 free:
 770         free_string(name);
 771 }
 772
 773 /* this is actually hooked from smatch_implied.c...  it's hacky, yes */
 774 void __extra_match_condition(struct expression *expr)
 775 {
 776         struct symbol *sym;
 777         char *name;
 778         struct smatch_state *pre_state;
 779         struct smatch_state *true_state;
 780         struct smatch_state *false_state;
 781
 782         expr = strip_expr(expr);
 783         switch (expr->type) {
 784         case EXPR_CALL:
 785                 function_comparison(SPECIAL_NOTEQUAL, expr, 0, 1);
 786                 return;
 787         case EXPR_PREOP:
 788         case EXPR_SYMBOL:
 789         case EXPR_DEREF:
 790                 name = get_variable_from_expr(expr, &sym);
 791                 if (!name)
 792                         return;
 793                 pre_state = get_state(my_id, name, sym);
 794                 true_state = add_filter(pre_state, 0);
 795                 if (possibly_true(SPECIAL_EQUAL, get_dinfo(pre_state), 0, 0))
 796                         false_state = alloc_extra_state(0);
 797                 else
 798                         false_state = alloc_extra_state_empty();
 799                 set_extra_true_false(name, sym, true_state, false_state);
 800                 free_string(name);
 801                 return;
 802         case EXPR_COMPARE:
 803                 match_comparison(expr);
 804                 return;
 805         case EXPR_ASSIGNMENT:
 806                 __extra_match_condition(expr->left);
 807                 return;
 808         }
 809 }
 810
 811 /* returns 1 if it is not possible for expr to be value, otherwise returns 0 */
 812 int implied_not_equal(struct expression *expr, long long val)
 813 {
 814         char *name;
 815         struct symbol *sym;
 816         struct smatch_state *state;
 817         int ret = 0;
 818
 819         name = get_variable_from_expr(expr, &sym);
 820         if (!name || !sym)
 821                 goto exit;
 822         state = get_state(my_id, name, sym);
 823         if (!state || !state->data)
 824                 goto exit;
 825         ret = !possibly_false(SPECIAL_NOTEQUAL, get_dinfo(state), val, 1);
 826 exit:
 827         free_string(name);
 828         return ret;
 829 }
 830
 831 int known_condition_true(struct expression *expr)
 832 {
 833         long long tmp;
 834
 835         if (!expr)
 836                 return 0;
 837
 838         if (get_value(expr, &tmp) && tmp)
 839                 return 1;
 840
 841         expr = strip_expr(expr);
 842         switch (expr->type) {
 843         case EXPR_PREOP:
 844                 if (expr->op == '!') {
 845                         if (known_condition_false(expr->unop))
 846                                 return 1;
 847                         break;
 848                 }
 849                 break;
 850         default:
 851                 break;
 852         }
 853         return 0;
 854 }
 855
 856 int known_condition_false(struct expression *expr)
 857 {
 858         if (!expr)
 859                 return 0;
 860
 861         if (is_zero(expr))
 862                 return 1;
 863
 864         switch (expr->type) {
 865         case EXPR_PREOP:
 866                 if (expr->op == '!') {
 867                         if (known_condition_true(expr->unop))
 868                                 return 1;
 869                         break;
 870                 }
 871                 break;
 872         default:
 873                 break;
 874         }
 875         return 0;
 876 }
 877
 878 static int do_comparison_range(struct expression *expr)
 879 {
 880         struct symbol *sym;
 881         char *name;
 882         struct smatch_state *state;
 883         long long value;
 884         int left = 0;
 885         int poss_true, poss_false;
 886
 887         if (!get_value(expr->left, &value)) {
 888                 if (!get_value(expr->right, &value))
 889                         return 3;
 890                 left = 1;
 891         }
 892         if (left)
 893                 name = get_variable_from_expr(expr->left, &sym);
 894         else
 895                 name = get_variable_from_expr(expr->right, &sym);
 896         if (!name || !sym)
 897                 goto free;
 898         state = get_state(SMATCH_EXTRA, name, sym);
 899         if (!state)
 900                 goto free;
 901         poss_true = possibly_true(expr->op, get_dinfo(state), value, left);
 902         poss_false = possibly_false(expr->op, get_dinfo(state), value, left);
 903         if (!poss_true && !poss_false)
 904                 return 0;
 905         if (poss_true && !poss_false)
 906                 return 1;
 907         if (!poss_true && poss_false)
 908                 return 2;
 909         if (poss_true && poss_false)
 910                 return 3;
 911 free:
 912         free_string(name);
 913         return 3;
 914 }
 915
 916 int implied_condition_true(struct expression *expr)
 917 {
 918         struct statement *stmt;
 919         long long tmp;
 920         long long val;
 921
 922         if (!expr)
 923                 return 0;
 924
 925         if (get_implied_value(expr, &tmp) && tmp)
 926                 return 1;
 927
 928         if (expr->type == EXPR_POSTOP)
 929                 return implied_condition_true(expr->unop);
 930
 931         if (expr->type == EXPR_PREOP && expr->op == SPECIAL_DECREMENT)
 932                 return implied_not_equal(expr->unop, 1);
 933         if (expr->type == EXPR_PREOP && expr->op == SPECIAL_INCREMENT)
 934                 return implied_not_equal(expr->unop, -1);
 935
 936         expr = strip_expr(expr);
 937         switch (expr->type) {
 938         case EXPR_COMPARE:
 939                 if (do_comparison_range(expr) == 1)
 940                         return 1;
 941                 break;
 942         case EXPR_PREOP:
 943                 if (expr->op == '!') {
 944                         if (implied_condition_false(expr->unop))
 945                                 return 1;
 946                         break;
 947                 }
 948                 stmt = get_block_thing(expr);
 949                 if (last_stmt_val(stmt, &val) && val == 1)
 950                         return 1;
 951                 break;
 952         default:
 953                 if (implied_not_equal(expr, 0) == 1)
 954                         return 1;
 955                 break;
 956         }
 957         return 0;
 958 }
 959
 960 int implied_condition_false(struct expression *expr)
 961 {
 962         struct statement *stmt;
 963         struct expression *tmp;
 964         long long val;
 965
 966         if (!expr)
 967                 return 0;
 968
 969         if (is_zero(expr))
 970                 return 1;
 971
 972         switch (expr->type) {
 973         case EXPR_COMPARE:
 974                 if (do_comparison_range(expr) == 2)
 975                         return 1;
 976         case EXPR_PREOP:
 977                 if (expr->op == '!') {
 978                         if (implied_condition_true(expr->unop))
 979                                 return 1;
 980                         break;
 981                 }
 982                 stmt = get_block_thing(expr);
 983                 if (last_stmt_val(stmt, &val) && val == 0)
 984                         return 1;
 985                 tmp = strip_expr(expr);
 986                 if (tmp != expr)
 987                         return implied_condition_false(tmp);
 988                 break;
 989         default:
 990                 if (get_implied_value(expr, &val) && val == 0)
 991                         return 1;
 992                 break;
 993         }
 994         return 0;
 995 }
 996
 997 int get_implied_range_list(struct expression *expr, struct range_list **rl)
 998 {
 999         long long val;
1000         struct smatch_state *state;
1001
1002         expr = strip_expr(expr);
1003
1004         state = get_state_expr(my_id, expr);
1005         if (state) {
1006                 *rl = clone_range_list(get_dinfo(state)->value_ranges);
1007                 return 1;
1008         }
1009
1010         if (get_implied_value(expr, &val)) {
1011                 *rl = NULL;
1012                 add_range(rl, val, val);
1013                 return 1;
1014         }
1015
1016         if (expr->type == EXPR_BINOP && expr->op == '%') {
1017                 if (!get_implied_value(expr->right, &val))
1018                         return 0;
1019                 *rl = NULL;
1020                 add_range(rl, 0, val - 1);
1021                 return 1;
1022         }
1023
1024         return 0;
1025 }
1026
1027 int is_whole_range(struct smatch_state *state)
1028 {
1029         struct data_info *dinfo;
1030         struct data_range *drange;
1031
1032         if (!state)
1033                 return 0;
1034         dinfo = get_dinfo(state);
1035         drange = first_ptr_list((struct ptr_list *)dinfo->value_ranges);
1036         if (drange->min == whole_range.min && drange->max == whole_range.max)
1037                 return 1;
1038         return 0;
1039 }
1040
1041 void register_smatch_extra(int id)
1042 {
1043         my_id = id;
1044         add_merge_hook(my_id, &merge_func);
1045         add_unmatched_state_hook(my_id, &unmatched_state);
1046         add_hook(&unop_expr, OP_HOOK);
1047         add_hook(&match_function_def, FUNC_DEF_HOOK);
1048         add_hook(&match_function_call, FUNCTION_CALL_HOOK);
1049         add_hook(&match_assign, ASSIGNMENT_HOOK);
1050         add_hook(&match_declarations, DECLARATION_HOOK);
1051 }