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
  15 #include <stdlib.h>
  16 #include <errno.h>
  17 #ifndef __USE_ISOC99
  18 #define __USE_ISOC99
  19 #endif
  20 #include <limits.h>
  21 #include "parse.h"
  22 #include "smatch.h"
  23 #include "smatch_slist.h"
  24 #include "smatch_extra.h"
  25
  26 static int my_id;
  27
  28 struct string_list *__ignored_macros = NULL;
  29 static int in_warn_on_macro()
  30 {
  31         struct statement *stmt;
  32         char *tmp;
  33         char *macro;
  34
  35         stmt = get_current_statement();
  36         macro = get_macro_name(stmt->pos);
  37         if (!macro)
  38                 return 0;
  39
  40         FOR_EACH_PTR(__ignored_macros, tmp) {
  41                 if (!strcmp(tmp, macro))
  42                         return 1;
  43         } END_FOR_EACH_PTR(tmp);
  44         return 0;
  45 }
  46
  47 struct sm_state *set_extra_mod(const char *name, struct symbol *sym, struct smatch_state *state)
  48 {
  49         if (in_warn_on_macro())
  50                 return NULL;
  51         remove_from_equiv(name, sym);
  52         return set_state(SMATCH_EXTRA, name, sym, state);
  53 }
  54
  55 struct sm_state *set_extra_expr_mod(struct expression *expr, struct smatch_state *state)
  56 {
  57         if (in_warn_on_macro())
  58                 return NULL;
  59         remove_from_equiv_expr(expr);
  60         return set_state_expr(SMATCH_EXTRA, expr, state);
  61 }
  62
  63 /*
  64  * This is for return_implies_state() hooks which modify a SMATCH_EXTRA state
  65  */
  66 void set_extra_expr_nomod(struct expression *expr, struct smatch_state *state)
  67 {
  68         struct relation *rel;
  69         struct smatch_state *orig_state;
  70
  71         orig_state = get_state_expr(SMATCH_EXTRA, expr);
  72
  73         if (!estate_related(orig_state)) {
  74                 set_state_expr(SMATCH_EXTRA, expr, state);
  75                 return;
  76         }
  77
  78         set_related(state, estate_related(orig_state));
  79         FOR_EACH_PTR(estate_related(orig_state), rel) {
  80                 if (option_debug_related)
  81                         sm_msg("updating related %s to %s", rel->name, state->name);
  82                 set_state(SMATCH_EXTRA, rel->name, rel->sym, state);
  83         } END_FOR_EACH_PTR(rel);
  84 }
  85
  86 static void set_extra_true_false(const char *name, struct symbol *sym,
  87                         struct smatch_state *true_state,
  88                         struct smatch_state *false_state)
  89 {
  90         struct relation *rel;
  91         struct smatch_state *orig_state;
  92
  93         if (in_warn_on_macro())
  94                 return;
  95
  96         orig_state = get_state(SMATCH_EXTRA, name, sym);
  97
  98         if (!estate_related(orig_state)) {
  99                 set_true_false_states(SMATCH_EXTRA, name, sym, true_state, false_state);
 100                 return;
 101         }
 102
 103         if (true_state)
 104                 set_related(true_state, estate_related(orig_state));
 105         if (false_state)
 106                 set_related(false_state, estate_related(orig_state));
 107
 108         FOR_EACH_PTR(estate_related(orig_state), rel) {
 109                 set_true_false_states(SMATCH_EXTRA, rel->name, rel->sym,
 110                                 true_state, false_state);
 111         } END_FOR_EACH_PTR(rel);
 112 }
 113
 114 static void set_extra_expr_true_false(struct expression *expr,
 115                 struct smatch_state *true_state,
 116                 struct smatch_state *false_state)
 117 {
 118         char *name;
 119         struct symbol *sym;
 120
 121         expr = strip_expr(expr);
 122         name = get_variable_from_expr(expr, &sym);
 123         if (!name || !sym)
 124                 goto free;
 125         set_extra_true_false(name, sym, true_state, false_state);
 126 free:
 127         free_string(name);
 128 }
 129
 130 struct smatch_state *filter_range(struct smatch_state *orig,
 131                                  sval_t filter_min, sval_t filter_max)
 132 {
 133         struct range_list *rl;
 134
 135         if (!orig)
 136                 orig = extra_undefined(filter_min.type);
 137
 138         rl = remove_range(estate_ranges(orig), filter_min, filter_max);
 139         return alloc_estate_range_list(rl);
 140 }
 141
 142 struct smatch_state *add_filter(struct smatch_state *orig, sval_t sval)
 143 {
 144         return filter_range(orig, sval, sval);
 145 }
 146
 147 static struct smatch_state *merge_func(struct smatch_state *s1, struct smatch_state *s2)
 148 {
 149         struct smatch_state *tmp;
 150         struct range_list *value_ranges;
 151         struct related_list *rlist;
 152
 153         if (estates_equiv(s1, s2))
 154                 return s1;
 155
 156         value_ranges = range_list_union(estate_ranges(s1), estate_ranges(s2));
 157         tmp = alloc_estate_range_list(value_ranges);
 158         rlist = get_shared_relations(estate_related(s1), estate_related(s2));
 159         set_related(tmp, rlist);
 160         if (estate_has_hard_max(s1) && estate_has_hard_max(s2))
 161                 estate_set_hard_max(tmp);
 162
 163         return tmp;
 164 }
 165
 166 static struct sm_state *handle_canonical_while_count_down(struct statement *loop)
 167 {
 168         struct expression *iter_var;
 169         struct expression *condition;
 170         struct sm_state *sm;
 171         struct smatch_state *estate;
 172         sval_t start;
 173
 174         condition = strip_expr(loop->iterator_pre_condition);
 175         if (!condition)
 176                 return NULL;
 177         if (condition->type != EXPR_PREOP && condition->type != EXPR_POSTOP)
 178                 return NULL;
 179         if (condition->op != SPECIAL_DECREMENT)
 180                 return NULL;
 181
 182         iter_var = condition->unop;
 183         sm = get_sm_state_expr(SMATCH_EXTRA, iter_var);
 184         if (!sm)
 185                 return NULL;
 186         if (sval_cmp_val(estate_min(sm->state), 0) < 0)
 187                 return NULL;
 188         start = estate_max(sm->state);
 189         if  (sval_cmp_val(start, 0) <= 0)
 190                 return NULL;
 191         if (!sval_is_max(start))
 192                 start.value--;
 193
 194         if (condition->type == EXPR_PREOP) {
 195                 estate = alloc_estate_range(sval_type_val(start.type, 1), start);
 196                 if (!sval_is_max(start))
 197                         estate_set_hard_max(estate);
 198                 set_extra_expr_mod(iter_var, estate);
 199         }
 200         if (condition->type == EXPR_POSTOP) {
 201                 estate = alloc_estate_range(sval_type_val(start.type, 0), start);
 202                 if (!sval_is_max(start))
 203                         estate_set_hard_max(estate);
 204                 set_extra_expr_mod(iter_var, estate);
 205         }
 206         return get_sm_state_expr(SMATCH_EXTRA, iter_var);
 207 }
 208
 209 static struct sm_state *handle_canonical_for_inc(struct expression *iter_expr,
 210                                                 struct expression *condition)
 211 {
 212         struct expression *iter_var;
 213         struct sm_state *sm;
 214         struct smatch_state *estate;
 215         sval_t start, end;
 216
 217         iter_var = iter_expr->unop;
 218         sm = get_sm_state_expr(SMATCH_EXTRA, iter_var);
 219         if (!sm)
 220                 return NULL;
 221         if (!estate_get_single_value(sm->state, &start))
 222                 return NULL;
 223         if (!get_implied_value(condition->right, &end))
 224                 end = sval_type_max(get_type(iter_var));
 225
 226         if (get_sm_state_expr(SMATCH_EXTRA, condition->left) != sm)
 227                 return NULL;
 228
 229         switch (condition->op) {
 230         case SPECIAL_NOTEQUAL:
 231         case '<':
 232                 if (!sval_is_max(end))
 233                         end.value--;
 234                 break;
 235         case SPECIAL_LTE:
 236                 break;
 237         default:
 238                 return NULL;
 239         }
 240         if (sval_cmp(end, start) < 0)
 241                 return NULL;
 242         estate = alloc_estate_range(start, end);
 243         if (!sval_is_max(end))
 244                 estate_set_hard_max(estate);
 245         set_extra_expr_mod(iter_var, estate);
 246         return get_sm_state_expr(SMATCH_EXTRA, iter_var);
 247 }
 248
 249 static struct sm_state *handle_canonical_for_dec(struct expression *iter_expr,
 250                                                 struct expression *condition)
 251 {
 252         struct expression *iter_var;
 253         struct sm_state *sm;
 254         struct smatch_state *estate;
 255         sval_t start, end;
 256
 257         iter_var = iter_expr->unop;
 258         sm = get_sm_state_expr(SMATCH_EXTRA, iter_var);
 259         if (!sm)
 260                 return NULL;
 261         if (!estate_get_single_value(sm->state, &start))
 262                 return NULL;
 263         if (!get_implied_value(condition->right, &end))
 264                 end = sval_type_min(get_type(iter_var));
 265         if (get_sm_state_expr(SMATCH_EXTRA, condition->left) != sm)
 266                 return NULL;
 267
 268         switch (condition->op) {
 269         case SPECIAL_NOTEQUAL:
 270         case '>':
 271                 if (!sval_is_min(end) && !sval_is_max(end))
 272                         end.value++;
 273                 break;
 274         case SPECIAL_GTE:
 275                 break;
 276         default:
 277                 return NULL;
 278         }
 279         if (sval_cmp(end, start) > 0)
 280                 return NULL;
 281         estate = alloc_estate_range(end, start);
 282         estate_set_hard_max(estate);
 283         set_extra_expr_mod(iter_var, estate);
 284         return get_sm_state_expr(SMATCH_EXTRA, iter_var);
 285 }
 286
 287 static struct sm_state *handle_canonical_for_loops(struct statement *loop)
 288 {
 289         struct expression *iter_expr;
 290         struct expression *condition;
 291
 292         if (!loop->iterator_post_statement)
 293                 return NULL;
 294         if (loop->iterator_post_statement->type != STMT_EXPRESSION)
 295                 return NULL;
 296         iter_expr = loop->iterator_post_statement->expression;
 297         if (!loop->iterator_pre_condition)
 298                 return NULL;
 299         if (loop->iterator_pre_condition->type != EXPR_COMPARE)
 300                 return NULL;
 301         condition = loop->iterator_pre_condition;
 302
 303         if (iter_expr->op == SPECIAL_INCREMENT)
 304                 return handle_canonical_for_inc(iter_expr, condition);
 305         if (iter_expr->op == SPECIAL_DECREMENT)
 306                 return handle_canonical_for_dec(iter_expr, condition);
 307         return NULL;
 308 }
 309
 310 struct sm_state *__extra_handle_canonical_loops(struct statement *loop, struct state_list **slist)
 311 {
 312         struct sm_state *ret;
 313
 314         __push_fake_cur_slist();
 315         if (!loop->iterator_post_statement)
 316                 ret = handle_canonical_while_count_down(loop);
 317         else
 318                 ret = handle_canonical_for_loops(loop);
 319         *slist = __pop_fake_cur_slist();
 320         return ret;
 321 }
 322
 323 int __iterator_unchanged(struct sm_state *sm)
 324 {
 325         if (!sm)
 326                 return 0;
 327         if (get_sm_state(my_id, sm->name, sm->sym) == sm)
 328                 return 1;
 329         return 0;
 330 }
 331
 332 static void while_count_down_after(struct sm_state *sm, struct expression *condition)
 333 {
 334         sval_t after_value;
 335
 336         /* paranoid checking.  prolly not needed */
 337         condition = strip_expr(condition);
 338         if (!condition)
 339                 return;
 340         if (condition->type != EXPR_PREOP && condition->type != EXPR_POSTOP)
 341                 return;
 342         if (condition->op != SPECIAL_DECREMENT)
 343                 return;
 344         after_value = estate_min(sm->state);
 345         after_value.value--;
 346         set_extra_mod(sm->name, sm->sym, alloc_estate(after_value));
 347 }
 348
 349 void __extra_pre_loop_hook_after(struct sm_state *sm,
 350                                 struct statement *iterator,
 351                                 struct expression *condition)
 352 {
 353         struct expression *iter_expr;
 354         char *name;
 355         struct symbol *sym;
 356         sval_t value;
 357         int left = 0;
 358         struct smatch_state *state;
 359         sval_t min, max;
 360
 361         if (!iterator) {
 362                 while_count_down_after(sm, condition);
 363                 return;
 364         }
 365
 366         iter_expr = iterator->expression;
 367
 368         if (condition->type != EXPR_COMPARE)
 369                 return;
 370         if (!get_value(condition->left, &value)) {
 371                 if (!get_value(condition->right, &value))
 372                         return;
 373                 left = 1;
 374         }
 375         if (left)
 376                 name = get_variable_from_expr(condition->left, &sym);
 377         else
 378                 name = get_variable_from_expr(condition->right, &sym);
 379         if (!name || !sym)
 380                 goto free;
 381         if (sym != sm->sym || strcmp(name, sm->name))
 382                 goto free;
 383         state = get_state(my_id, name, sym);
 384         min = estate_min(state);
 385         max = estate_max(state);
 386         if (iter_expr->op == SPECIAL_INCREMENT &&
 387             !sval_is_min(min) && sval_is_max(max))
 388                 set_extra_mod(name, sym, alloc_estate(min));
 389         else if (sval_is_min(min) && !sval_is_max(max))
 390                 set_extra_mod(name, sym, alloc_estate(max));
 391
 392 free:
 393         free_string(name);
 394         return;
 395 }
 396
 397 static struct smatch_state *unmatched_state(struct sm_state *sm)
 398 {
 399         return extra_undefined(estate_type(sm->state));
 400 }
 401
 402 static void match_function_call(struct expression *expr)
 403 {
 404         struct expression *arg;
 405         struct expression *tmp;
 406
 407         FOR_EACH_PTR(expr->args, arg) {
 408                 tmp = strip_expr(arg);
 409                 if (tmp->type == EXPR_PREOP && tmp->op == '&') {
 410                         remove_from_equiv_expr(tmp->unop);
 411                         set_state_expr(SMATCH_EXTRA, tmp->unop, extra_undefined(get_type(tmp->unop)));
 412                 }
 413         } END_FOR_EACH_PTR(arg);
 414 }
 415
 416 static int types_equiv_or_pointer(struct symbol *one, struct symbol *two)
 417 {
 418         if (!one || !two)
 419                 return 0;
 420         if (one->type == SYM_PTR && two->type == SYM_PTR)
 421                 return 1;
 422         return types_equiv(one, two);
 423 }
 424
 425 static void match_assign(struct expression *expr)
 426 {
 427         struct range_list *rl = NULL;
 428         struct expression *left;
 429         struct expression *right;
 430         struct symbol *right_sym;
 431         char *right_name;
 432         struct symbol *sym;
 433         char *name;
 434         sval_t value;
 435         int known;
 436         sval_t right_min, right_max;
 437         sval_t tmp;
 438
 439         if (__is_condition_assign(expr))
 440                 return;
 441         left = strip_expr(expr->left);
 442         name = get_variable_from_expr(left, &sym);
 443         if (!name)
 444                 return;
 445         right = strip_parens(expr->right);
 446         while (right->type == EXPR_ASSIGNMENT && right->op == '=')
 447                 right = strip_parens(right->left);
 448
 449         if (expr->op == '=' && right->type == EXPR_CALL)
 450                 return;  /* these are handled in match_call_assign() */
 451
 452         right_name = get_variable_from_expr(right, &right_sym);
 453         if (expr->op == '=' && right_name && right_sym &&
 454             types_equiv_or_pointer(get_type(expr->left), get_type(expr->right))) {
 455                 set_equiv(left, right);
 456                 goto free;
 457         }
 458
 459         right_min = sval_type_min(get_type(expr->right));
 460         right_max = sval_type_max(get_type(expr->right));
 461
 462         known = get_implied_value(right, &value);
 463         switch (expr->op) {
 464         case '=': {
 465                 struct smatch_state *state;
 466
 467                 if (get_implied_range_list(right, &rl)) {
 468                         rl = cast_rl(get_type(expr->left), rl);
 469                         state = alloc_estate_range_list(rl);
 470                         if (get_hard_max(right, &tmp))
 471                                 estate_set_hard_max(state);
 472                 } else {
 473                         rl = whole_range_list(get_type(right));
 474                         rl = cast_rl(get_type(expr->left), rl);
 475                         state = alloc_estate_range_list(rl);
 476                 }
 477                 set_extra_mod(name, sym, state);
 478                 goto free;
 479         }
 480         case SPECIAL_ADD_ASSIGN:
 481                 if (get_implied_min(left, &tmp)) {
 482                         if (known)
 483                                 right_min = sval_binop(tmp, '+', value);
 484                         else
 485                                 right_min = tmp;
 486                 }
 487                 if (!inside_loop() && known && get_implied_max(left, &tmp))
 488                         right_max = sval_binop(tmp, '+', value);
 489                 break;
 490         case SPECIAL_SUB_ASSIGN:
 491                 if (get_implied_max(left, &tmp)) {
 492                         if (known)
 493                                 right_max = sval_binop(tmp, '-', value);
 494                         else
 495                                 right_max = tmp;
 496                 }
 497                 if (!inside_loop() && known && get_implied_min(left, &tmp))
 498                         right_min = sval_binop(tmp, '-', value);
 499                 break;
 500         }
 501         if (!sval_is_min(right_min) || !sval_is_max(right_max))
 502                 rl = cast_rl(get_type(expr->left), alloc_range_list(right_min, right_max));
 503         else
 504                 rl = whole_range_list(get_type(expr->left));
 505         set_extra_mod(name, sym, alloc_estate_range_list(rl));
 506 free:
 507         free_string(right_name);
 508         free_string(name);
 509 }
 510
 511 static void reset_struct_members(struct sm_state *sm)
 512 {
 513         set_extra_mod(sm->name, sm->sym, extra_undefined(estate_type(sm->state)));
 514 }
 515
 516 static struct smatch_state *increment_state(struct smatch_state *state)
 517 {
 518         sval_t min = estate_min(state);
 519         sval_t max = estate_max(state);
 520
 521         if (!estate_ranges(state))
 522                 return NULL;
 523
 524         if (inside_loop())
 525                 max = sval_type_max(max.type);
 526
 527         if (!sval_is_min(min) && !sval_is_max(min))
 528                 min.value++;
 529         if (!sval_is_min(max) && !sval_is_max(max))
 530                 max.value++;
 531         return alloc_estate_range(min, max);
 532 }
 533
 534 static struct smatch_state *decrement_state(struct smatch_state *state)
 535 {
 536         sval_t min = estate_min(state);
 537         sval_t max = estate_max(state);
 538
 539         if (!estate_ranges(state))
 540                 return NULL;
 541
 542         if (inside_loop())
 543                 min = sval_type_min(min.type);
 544
 545         if (!sval_is_min(min) && !sval_is_max(min))
 546                 min.value--;
 547         if (!sval_is_min(max) && !sval_is_max(max))
 548                 max.value--;
 549         return alloc_estate_range(min, max);
 550 }
 551
 552 static void unop_expr(struct expression *expr)
 553 {
 554         struct smatch_state *state;
 555
 556         if (expr->smatch_flags & Handled)
 557                 return;
 558
 559         switch (expr->op) {
 560         case SPECIAL_INCREMENT:
 561                 state = get_state_expr(SMATCH_EXTRA, expr->unop);
 562                 state = increment_state(state);
 563                 if (!state)
 564                         state = extra_undefined(get_type(expr));
 565                 set_extra_expr_mod(expr->unop, state);
 566                 break;
 567         case SPECIAL_DECREMENT:
 568                 state = get_state_expr(SMATCH_EXTRA, expr->unop);
 569                 state = decrement_state(state);
 570                 if (!state)
 571                         state = extra_undefined(get_type(expr));
 572                 set_extra_expr_mod(expr->unop, state);
 573                 break;
 574         default:
 575                 return;
 576         }
 577 }
 578
 579 static void asm_expr(struct statement *stmt)
 580 {
 581
 582         struct expression *expr;
 583         int state = 0;
 584
 585         FOR_EACH_PTR(stmt->asm_outputs, expr) {
 586                 switch (state) {
 587                 case 0: /* identifier */
 588                 case 1: /* constraint */
 589                         state++;
 590                         continue;
 591                 case 2: /* expression */
 592                         state = 0;
 593                         set_extra_expr_mod(expr, extra_undefined(get_type(expr)));
 594                         continue;
 595                 }
 596         } END_FOR_EACH_PTR(expr);
 597 }
 598
 599 static void delete_state_tracker(struct tracker *t)
 600 {
 601         remove_from_equiv(t->name, t->sym);
 602         delete_state(t->owner, t->name, t->sym);
 603 }
 604
 605 static void scoped_state_extra(const char *name, struct symbol *sym)
 606 {
 607         struct tracker *t;
 608
 609         t = alloc_tracker(SMATCH_EXTRA, name, sym);
 610         add_scope_hook((scope_hook *)&delete_state_tracker, t);
 611 }
 612
 613 static void match_declarations(struct symbol *sym)
 614 {
 615         const char *name;
 616
 617         if (sym->ident) {
 618                 name = sym->ident->name;
 619                 if (!sym->initializer) {
 620                         set_state(SMATCH_EXTRA, name, sym, extra_undefined(get_real_base_type(sym)));
 621                         scoped_state_extra(name, sym);
 622                 }
 623         }
 624 }
 625
 626 static void check_dereference(struct expression *expr)
 627 {
 628         set_extra_expr_nomod(expr, alloc_estate_range(valid_ptr_min_sval, valid_ptr_max_sval));
 629 }
 630
 631 static void match_dereferences(struct expression *expr)
 632 {
 633         if (expr->type != EXPR_PREOP)
 634                 return;
 635         check_dereference(expr->unop);
 636 }
 637
 638 static void match_pointer_as_array(struct expression *expr)
 639 {
 640         if (!is_array(expr))
 641                 return;
 642         check_dereference(expr->unop->left);
 643 }
 644
 645 static void set_param_dereferenced(struct expression *arg, char *unused)
 646 {
 647         check_dereference(arg);
 648 }
 649
 650 static void match_function_def(struct symbol *sym)
 651 {
 652         struct symbol *arg;
 653
 654         FOR_EACH_PTR(sym->ctype.base_type->arguments, arg) {
 655                 if (!arg->ident)
 656                         continue;
 657                 set_state(my_id, arg->ident->name, arg, extra_undefined(get_real_base_type(arg)));
 658         } END_FOR_EACH_PTR(arg);
 659 }
 660
 661 static int match_func_comparison(struct expression *expr)
 662 {
 663         struct expression *left = strip_expr(expr->left);
 664         struct expression *right = strip_expr(expr->right);
 665         sval_t sval;
 666
 667         if (left->type == EXPR_CALL) {
 668                 if (!get_implied_value(right, &sval))
 669                         return 1;
 670                 function_comparison(expr->op, left, sval, 1);
 671                 return 1;
 672         }
 673
 674         if (right->type == EXPR_CALL) {
 675                 if (!get_implied_value(left, &sval))
 676                         return 1;
 677                 function_comparison(expr->op, right, sval, 0);
 678                 return 1;
 679         }
 680
 681         return 0;
 682 }
 683
 684 static sval_t add_one(sval_t sval)
 685 {
 686         sval.value++;
 687         return sval;
 688 }
 689
 690 static sval_t sub_one(sval_t sval)
 691 {
 692         sval.value--;
 693         return sval;
 694 }
 695
 696 static void match_comparison(struct expression *expr)
 697 {
 698         struct expression *left = strip_expr(expr->left);
 699         struct expression *right = strip_expr(expr->right);
 700         struct symbol *type;
 701         struct range_list *left_orig;
 702         struct range_list *left_true;
 703         struct range_list *left_false;
 704         struct range_list *right_orig;
 705         struct range_list *right_true;
 706         struct range_list *right_false;
 707         struct smatch_state *left_true_state;
 708         struct smatch_state *left_false_state;
 709         struct smatch_state *right_true_state;
 710         struct smatch_state *right_false_state;
 711         sval_t min, max, dummy;
 712         int left_postop = 0;
 713         int right_postop = 0;
 714
 715         if (match_func_comparison(expr))
 716                 return;
 717
 718         if (left->op == SPECIAL_INCREMENT || left->op == SPECIAL_DECREMENT) {
 719                 if (left->type == EXPR_POSTOP) {
 720                         left->smatch_flags |= Handled;
 721                         left_postop = left->op;
 722                 }
 723                 left = strip_expr(left->unop);
 724         }
 725         while (left->type == EXPR_ASSIGNMENT)
 726                 left = strip_expr(left->left);
 727
 728         if (right->op == SPECIAL_INCREMENT || right->op == SPECIAL_DECREMENT) {
 729                 if (right->type == EXPR_POSTOP) {
 730                         right->smatch_flags |= Handled;
 731                         right_postop = right->op;
 732                 }
 733                 right = strip_expr(right->unop);
 734         }
 735
 736         type = get_type(expr);
 737         if (!type) {
 738                 sm_msg("debug: failed to get type for '%s'", get_variable_from_expr_complex(expr, NULL));
 739                 type = &llong_ctype;
 740         }
 741
 742         if (get_implied_range_list(left, &left_orig)) {
 743                 left_orig = cast_rl(type, left_orig);
 744         } else {
 745                 min = sval_type_min(get_type(left));
 746                 max = sval_type_max(get_type(left));
 747                 left_orig = cast_rl(type, alloc_range_list(min, max));
 748         }
 749
 750         if (get_implied_range_list(right, &right_orig)) {
 751                 right_orig = cast_rl(type, right_orig);
 752         } else {
 753                 min = sval_type_min(get_type(right));
 754                 max = sval_type_max(get_type(right));
 755                 right_orig = cast_rl(type, alloc_range_list(min, max));
 756         }
 757         min = sval_type_min(type);
 758         max = sval_type_max(type);
 759
 760         left_true = clone_range_list(left_orig);
 761         left_false = clone_range_list(left_orig);
 762         right_true = clone_range_list(right_orig);
 763         right_false = clone_range_list(right_orig);
 764
 765         switch (expr->op) {
 766         case '<':
 767         case SPECIAL_UNSIGNED_LT:
 768                 if (!sval_is_max(rl_max(right_orig))) {
 769                         left_true = remove_range(left_orig, rl_max(right_orig), max);
 770                 }
 771                 if (!sval_is_min(rl_min(right_orig))) {
 772                         left_false = remove_range(left_orig, min, sub_one(rl_min(right_orig)));
 773                 }
 774
 775                 if (!sval_is_min(rl_min(left_orig)))
 776                         right_true = remove_range(right_orig, min, rl_min(left_orig));
 777                 if (!sval_is_max(rl_max(left_orig)))
 778                         right_false = remove_range(right_orig, add_one(rl_max(left_orig)), max);
 779                 break;
 780         case SPECIAL_UNSIGNED_LTE:
 781         case SPECIAL_LTE:
 782                 if (!sval_is_max(rl_max(right_orig)))
 783                         left_true = remove_range(left_orig, add_one(rl_max(right_orig)), max);
 784                 if (!sval_is_min(rl_min(right_orig)))
 785                         left_false = remove_range(left_orig, min, rl_min(right_orig));
 786
 787                 if (!sval_is_min(rl_min(left_orig)))
 788                         right_true = remove_range(right_orig, min, sub_one(rl_min(left_orig)));
 789                 if (!sval_is_max(rl_max(left_orig)))
 790                         right_false = remove_range(right_orig, rl_max(left_orig), max);
 791                 break;
 792         case SPECIAL_EQUAL:
 793                 if (!sval_is_max(rl_max(right_orig))) {
 794                         left_true = remove_range(left_true, add_one(rl_max(right_orig)), max);
 795                 }
 796                 if (!sval_is_min(rl_min(right_orig))) {
 797                         left_true = remove_range(left_true, min, sub_one(rl_min(right_orig)));
 798                 }
 799                 if (sval_cmp(rl_min(right_orig), rl_max(right_orig)) == 0)
 800                         left_false = remove_range(left_orig, rl_min(right_orig), rl_min(right_orig));
 801
 802                 if (!sval_is_max(rl_max(left_orig)))
 803                         right_true = remove_range(right_true, add_one(rl_max(left_orig)), max);
 804                 if (!sval_is_min(rl_min(left_orig)))
 805                         right_true = remove_range(right_true, min, sub_one(rl_min(left_orig)));
 806                 if (sval_cmp(rl_min(left_orig), rl_max(left_orig)) == 0)
 807                         right_false = remove_range(right_orig, rl_min(left_orig), rl_min(left_orig));
 808                 break;
 809         case SPECIAL_UNSIGNED_GTE:
 810         case SPECIAL_GTE:
 811                 if (!sval_is_min(rl_min(right_orig)))
 812                         left_true = remove_range(left_orig, min, sub_one(rl_min(right_orig)));
 813                 if (!sval_is_max(rl_max(right_orig)))
 814                         left_false = remove_range(left_orig, rl_max(right_orig), max);
 815
 816                 if (!sval_is_max(rl_max(left_orig)))
 817                         right_true = remove_range(right_orig, add_one(rl_max(left_orig)), max);
 818                 if (!sval_is_min(rl_min(left_orig)))
 819                         right_false = remove_range(right_orig, min, rl_min(left_orig));
 820                 break;
 821         case '>':
 822         case SPECIAL_UNSIGNED_GT:
 823                 if (!sval_is_min(rl_min(right_orig)))
 824                         left_true = remove_range(left_orig, min, rl_min(right_orig));
 825                 if (!sval_is_max(rl_max(right_orig)))
 826                         left_false = remove_range(left_orig, add_one(rl_max(right_orig)), max);
 827
 828                 if (!sval_is_max(rl_max(left_orig)))
 829                         right_true = remove_range(right_orig, rl_max(left_orig), max);
 830                 if (!sval_is_min(rl_min(left_orig)))
 831                         right_false = remove_range(right_orig, min, sub_one(rl_min(left_orig)));
 832                 break;
 833         case SPECIAL_NOTEQUAL:
 834                 if (!sval_is_max(rl_max(right_orig)))
 835                         left_false = remove_range(left_false, add_one(rl_max(right_orig)), max);
 836                 if (!sval_is_min(rl_min(right_orig)))
 837                         left_false = remove_range(left_false, min, sub_one(rl_min(right_orig)));
 838                 if (sval_cmp(rl_min(right_orig), rl_max(right_orig)) == 0)
 839                         left_true = remove_range(left_orig, rl_min(right_orig), rl_min(right_orig));
 840
 841                 if (!sval_is_max(rl_max(left_orig)))
 842                         right_false = remove_range(right_false, add_one(rl_max(left_orig)), max);
 843                 if (!sval_is_min(rl_min(left_orig)))
 844                         right_false = remove_range(right_false, min, sub_one(rl_min(left_orig)));
 845                 if (sval_cmp(rl_min(left_orig), rl_max(left_orig)) == 0)
 846                         right_true = remove_range(right_orig, rl_min(left_orig), rl_min(left_orig));
 847                 break;
 848         default:
 849                 return;
 850         }
 851
 852         left_true_state = alloc_estate_range_list(cast_rl(get_type(left), left_true));
 853         left_false_state = alloc_estate_range_list(cast_rl(get_type(left), left_false));
 854         right_true_state = alloc_estate_range_list(cast_rl(get_type(right), right_true));
 855         right_false_state = alloc_estate_range_list(cast_rl(get_type(right), right_false));
 856
 857         switch (expr->op) {
 858         case '<':
 859         case SPECIAL_UNSIGNED_LT:
 860         case SPECIAL_UNSIGNED_LTE:
 861         case SPECIAL_LTE:
 862                 if (get_hard_max(right, &dummy))
 863                         estate_set_hard_max(left_true_state);
 864                 if (get_hard_max(left, &dummy))
 865                         estate_set_hard_max(right_false_state);
 866                 break;
 867         case '>':
 868         case SPECIAL_UNSIGNED_GT:
 869         case SPECIAL_UNSIGNED_GTE:
 870         case SPECIAL_GTE:
 871                 if (get_hard_max(left, &dummy))
 872                         estate_set_hard_max(right_true_state);
 873                 if (get_hard_max(right, &dummy))
 874                         estate_set_hard_max(left_false_state);
 875                 break;
 876         }
 877
 878         if (get_hard_max(left, &dummy)) {
 879                 estate_set_hard_max(left_true_state);
 880                 estate_set_hard_max(left_false_state);
 881         }
 882         if (get_hard_max(right, &dummy)) {
 883                 estate_set_hard_max(right_true_state);
 884                 estate_set_hard_max(right_false_state);
 885         }
 886
 887         if (left_postop == SPECIAL_INCREMENT) {
 888                 left_true_state = increment_state(left_true_state);
 889                 left_false_state = increment_state(left_false_state);
 890         }
 891         if (left_postop == SPECIAL_DECREMENT) {
 892                 left_true_state = decrement_state(left_true_state);
 893                 left_false_state = decrement_state(left_false_state);
 894         }
 895         if (right_postop == SPECIAL_INCREMENT) {
 896                 right_true_state = increment_state(right_true_state);
 897                 right_false_state = increment_state(right_false_state);
 898         }
 899         if (right_postop == SPECIAL_DECREMENT) {
 900                 right_true_state = decrement_state(right_true_state);
 901                 right_false_state = decrement_state(right_false_state);
 902         }
 903
 904         set_extra_expr_true_false(left, left_true_state, left_false_state);
 905         set_extra_expr_true_false(right, right_true_state, right_false_state);
 906 }
 907
 908 /* this is actually hooked from smatch_implied.c...  it's hacky, yes */
 909 void __extra_match_condition(struct expression *expr)
 910 {
 911         struct symbol *sym;
 912         char *name;
 913         struct smatch_state *pre_state;
 914         struct smatch_state *true_state;
 915         struct smatch_state *false_state;
 916
 917         expr = strip_expr(expr);
 918         switch (expr->type) {
 919         case EXPR_CALL:
 920                 function_comparison(SPECIAL_NOTEQUAL, expr, ll_to_sval(0), 1);
 921                 return;
 922         case EXPR_PREOP:
 923         case EXPR_SYMBOL:
 924         case EXPR_DEREF: {
 925                 sval_t zero;
 926
 927                 zero = sval_blank(expr);
 928                 zero.value = 0;
 929
 930                 name = get_variable_from_expr(expr, &sym);
 931                 if (!name)
 932                         return;
 933                 pre_state = get_state(my_id, name, sym);
 934                 true_state = add_filter(pre_state, zero);
 935                 if (possibly_true(expr, SPECIAL_EQUAL, zero_expr()))
 936                         false_state = alloc_estate(zero);
 937                 else
 938                         false_state = alloc_estate_empty();
 939                 set_extra_true_false(name, sym, true_state, false_state);
 940                 free_string(name);
 941                 return;
 942         }
 943         case EXPR_COMPARE:
 944                 match_comparison(expr);
 945                 return;
 946         case EXPR_ASSIGNMENT:
 947                 __extra_match_condition(expr->left);
 948                 return;
 949         }
 950 }
 951
 952 /* returns 1 if it is not possible for expr to be value, otherwise returns 0 */
 953 int implied_not_equal(struct expression *expr, long long val)
 954 {
 955         return !possibly_false(expr, SPECIAL_NOTEQUAL, value_expr(val));
 956 }
 957
 958 int get_implied_range_list(struct expression *expr, struct range_list **rl)
 959 {
 960         sval_t sval;
 961         struct smatch_state *state;
 962         sval_t min, max;
 963
 964         *rl = NULL;
 965
 966         expr = strip_parens(expr);
 967         if (!expr)
 968                 return 0;
 969
 970         state = get_state_expr(my_id, expr);
 971         if (state) {
 972                 *rl = clone_range_list(estate_ranges(state));
 973                 goto out;
 974         }
 975
 976         if (expr->type == EXPR_CALL) {
 977                 if (get_implied_return(expr, rl))
 978                         goto out;
 979                 *rl = db_return_vals(expr);
 980                 goto out;
 981         }
 982
 983         if (get_implied_value(expr, &sval)) {
 984                 add_range(rl, sval, sval);
 985                 goto out;
 986         }
 987
 988         if (expr->type == EXPR_BINOP && expr->op == '%') {
 989                 if (!get_implied_value(expr->right, &sval))
 990                         return 0;
 991                 add_range(rl, ll_to_sval(0), ll_to_sval(sval.value - 1));
 992                 goto out;
 993         }
 994
 995         if (!get_implied_min(expr, &min))
 996                 return 0;
 997         if (!get_implied_max(expr, &max))
 998                 return 0;
 999
1000         *rl = alloc_range_list(min, max);
1001
1002 out:
1003         if (is_whole_range_rl(*rl))
1004                 return 0;
1005         return 1;
1006 }
1007
1008 static struct symbol *get_arg_type(struct expression *fn, int arg)
1009 {
1010         struct symbol *fn_type;
1011         struct symbol *tmp;
1012         struct symbol *arg_type;
1013         int i;
1014
1015         fn_type = get_type(fn);
1016         if (!fn_type)
1017                 return NULL;
1018         if (fn_type->type == SYM_PTR)
1019                 fn_type = get_real_base_type(fn_type);
1020         if (fn_type->type != SYM_FN)
1021                 return NULL;
1022
1023         i = 0;
1024         FOR_EACH_PTR(fn_type->arguments, tmp) {
1025                 arg_type = get_real_base_type(tmp);
1026                 if (i == arg) {
1027                         return arg_type;
1028                 }
1029                 i++;
1030         } END_FOR_EACH_PTR(tmp);
1031
1032         return NULL;
1033 }
1034
1035 int is_whole_range(struct smatch_state *state)
1036 {
1037         return is_whole_range_rl(estate_ranges(state));
1038 }
1039
1040 static void struct_member_callback(char *fn, char *global_static, int param, char *printed_name, struct smatch_state *state)
1041 {
1042         if (is_whole_range(state))
1043                 return;
1044         sm_msg("info: passes param_value '%s' %d '%s' %s %s", fn, param, printed_name, state->name, global_static);
1045 }
1046
1047 static void match_call_info(struct expression *expr)
1048 {
1049         struct range_list *rl = NULL;
1050         struct expression *arg;
1051         struct symbol *type;
1052         char *name;
1053         int i = 0;
1054
1055         name = get_fnptr_name(expr->fn);
1056         if (!name)
1057                 return;
1058
1059         FOR_EACH_PTR(expr->args, arg) {
1060                 type = get_arg_type(expr->fn, i);
1061
1062                 if (get_implied_range_list(arg, &rl))
1063                         rl = cast_rl(type, rl);
1064                 else
1065                         rl = whole_range_list(type);
1066
1067                 sm_msg("info: passes param_value '%s' %d '$$' %s %s",
1068                        name, i, show_ranges(rl),
1069                        is_static(expr->fn) ? "static" : "global");
1070                 i++;
1071         } END_FOR_EACH_PTR(arg);
1072
1073         free_string(name);
1074 }
1075
1076 static void set_param_value(const char *name, struct symbol *sym, char *key, char *value)
1077 {
1078         struct range_list *rl = NULL;
1079         struct smatch_state *state;
1080         char fullname[256];
1081
1082         if (strncmp(key, "$$", 2))
1083                 return;
1084
1085         snprintf(fullname, 256, "%s%s", name, key + 2);
1086         parse_value_ranges_type(get_real_base_type(sym), value, &rl);
1087         state = alloc_estate_range_list(rl);
1088         set_state(SMATCH_EXTRA, fullname, sym, state);
1089 }
1090
1091 static void match_call_assign(struct expression *expr)
1092 {
1093         if (expr->op != '=')
1094                 return;
1095
1096         /* if we have a db set up this gets set in smatch_function_hooks.c */
1097         if (option_no_db)
1098                 set_extra_expr_mod(expr->left, extra_undefined(get_type(expr->left)));
1099 }
1100
1101 void register_smatch_extra(int id)
1102 {
1103         my_id = id;
1104
1105         add_merge_hook(my_id, &merge_func);
1106         add_unmatched_state_hook(my_id, &unmatched_state);
1107         add_hook(&unop_expr, OP_HOOK);
1108         add_hook(&asm_expr, ASM_HOOK);
1109         add_hook(&match_function_def, FUNC_DEF_HOOK);
1110         add_hook(&match_declarations, DECLARATION_HOOK);
1111         if (option_info) {
1112                 add_hook(&match_call_info, FUNCTION_CALL_HOOK);
1113                 add_member_info_callback(my_id, struct_member_callback);
1114         }
1115         add_definition_db_callback(set_param_value, PARAM_VALUE);
1116 }
1117
1118 void register_smatch_extra_late(int id)
1119 {
1120         add_hook(&match_dereferences, DEREF_HOOK);
1121         add_hook(&match_pointer_as_array, OP_HOOK);
1122         add_db_fn_call_callback(DEREFERENCE, &set_param_dereferenced);
1123         add_indirect_modification_hook(SMATCH_EXTRA, reset_struct_members);
1124         add_hook(&match_function_call, FUNCTION_CALL_HOOK);
1125         add_hook(&match_assign, ASSIGNMENT_HOOK);
1126         add_hook(&match_call_assign, CALL_ASSIGNMENT_HOOK);
1127 }