smatch_helper.c

   1 /*
   2  * Copyright (C) 2006 Dan Carpenter.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License
   6  * as published by the Free Software Foundation; either version 2
   7  * of the License, or (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, see http://www.gnu.org/copyleft/gpl.txt
  16  */
  17
  18 /*
  19  * Miscellaneous helper functions.
  20  */
  21
  22 #include <stdlib.h>
  23 #include <stdio.h>
  24 #include "allocate.h"
  25 #include "smatch.h"
  26 #include "smatch_extra.h"
  27
  28 #define VAR_LEN 512
  29
  30 char *alloc_string(const char *str)
  31 {
  32         char *tmp;
  33
  34         if (!str)
  35                 return NULL;
  36         tmp = malloc(strlen(str) + 1);
  37         strcpy(tmp, str);
  38         return tmp;
  39 }
  40
  41 void free_string(char *str)
  42 {
  43         free(str);
  44 }
  45
  46 void remove_parens(char *str)
  47 {
  48         char *src, *dst;
  49
  50         dst = src = str;
  51         while (*src != '\0') {
  52                 if (*src == '(' || *src == ')') {
  53                         src++;
  54                         continue;
  55                 }
  56                 *dst++ = *src++;
  57         }
  58         *dst = *src;
  59 }
  60
  61 struct smatch_state *alloc_state_num(int num)
  62 {
  63         struct smatch_state *state;
  64         static char buff[256];
  65
  66         state = __alloc_smatch_state(0);
  67         snprintf(buff, 255, "%d", num);
  68         buff[255] = '\0';
  69         state->name = alloc_string(buff);
  70         state->data = INT_PTR(num);
  71         return state;
  72 }
  73
  74 struct smatch_state *alloc_state_str(const char *name)
  75 {
  76         struct smatch_state *state;
  77
  78         state = __alloc_smatch_state(0);
  79         state->name = alloc_string(name);
  80         return state;
  81 }
  82
  83 void append(char *dest, const char *data, int buff_len)
  84 {
  85         strncat(dest, data, buff_len - strlen(dest) - 1);
  86 }
  87
  88 /*
  89  * If you have "foo(a, b, 1);" then use
  90  * get_argument_from_call_expr(expr, 0) to return the expression for
  91  * a.  Yes, it does start counting from 0.
  92  */
  93 struct expression *get_argument_from_call_expr(struct expression_list *args,
  94                                                int num)
  95 {
  96         struct expression *expr;
  97         int i = 0;
  98
  99         if (!args)
 100                 return NULL;
 101
 102         FOR_EACH_PTR(args, expr) {
 103                 if (i == num)
 104                         return expr;
 105                 i++;
 106         } END_FOR_EACH_PTR(expr);
 107         return NULL;
 108 }
 109
 110 static struct expression *get_array_expr(struct expression *expr)
 111 {
 112         struct symbol *type;
 113
 114         if (expr->type != EXPR_BINOP || expr->op != '+')
 115                 return NULL;
 116
 117         type = get_type(expr->left);
 118         if (!type || type->type != SYM_ARRAY)
 119                 return NULL;
 120         return expr->left;
 121 }
 122
 123 static void __get_variable_from_expr(struct symbol **sym_ptr, char *buf,
 124                                      struct expression *expr, int len,
 125                                      int *complicated, int no_parens)
 126 {
 127         switch (expr->type) {
 128         case EXPR_DEREF: {
 129                 struct expression *deref;
 130                 int op;
 131
 132                 deref = expr->deref;
 133                 op = deref->op;
 134                 if (op == '*') {
 135                         struct expression *unop = strip_expr(deref->unop);
 136
 137                         if (unop->type == EXPR_PREOP && unop->op == '&') {
 138                                 deref = unop->unop;
 139                                 op = '.';
 140                         } else {
 141                                 deref = deref->unop;
 142                                 if (!is_pointer(deref))
 143                                         op = '.';
 144                         }
 145                 }
 146
 147                 __get_variable_from_expr(sym_ptr, buf, deref, len, complicated, no_parens);
 148
 149                 if (op == '*')
 150                         append(buf, "->", len);
 151                 else
 152                         append(buf, ".", len);
 153
 154                 if (expr->member)
 155                         append(buf, expr->member->name, len);
 156                 else
 157                         append(buf, "unknown_member", len);
 158
 159                 return;
 160         }
 161         case EXPR_SYMBOL:
 162                 if (expr->symbol_name)
 163                         append(buf, expr->symbol_name->name, len);
 164                 if (sym_ptr) {
 165                         if (*sym_ptr)
 166                                 *complicated = 1;
 167                         *sym_ptr = expr->symbol;
 168                 }
 169                 return;
 170         case EXPR_PREOP: {
 171                 const char *tmp;
 172
 173                 if (get_expression_statement(expr)) {
 174                         *complicated = 2;
 175                         return;
 176                 }
 177
 178                 if (expr->op == '(') {
 179                         if (!no_parens)
 180                                 append(buf, "(", len);
 181                 } else if (expr->op != '*' || !get_array_expr(expr->unop)) {
 182                         tmp = show_special(expr->op);
 183                         append(buf, tmp, len);
 184                 }
 185                 __get_variable_from_expr(sym_ptr, buf, expr->unop,
 186                                                  len, complicated, no_parens);
 187
 188                 if (expr->op == '(' && !no_parens)
 189                         append(buf, ")", len);
 190
 191                 if (expr->op == SPECIAL_DECREMENT ||
 192                                 expr->op == SPECIAL_INCREMENT)
 193                         *complicated = 1;
 194
 195                 return;
 196         }
 197         case EXPR_POSTOP: {
 198                 const char *tmp;
 199
 200                 __get_variable_from_expr(sym_ptr, buf, expr->unop,
 201                                                  len, complicated, no_parens);
 202                 tmp = show_special(expr->op);
 203                 append(buf, tmp, len);
 204
 205                 if (expr->op == SPECIAL_DECREMENT || expr->op == SPECIAL_INCREMENT)
 206                         *complicated = 1;
 207                 return;
 208         }
 209         case EXPR_ASSIGNMENT:
 210         case EXPR_COMPARE:
 211         case EXPR_LOGICAL:
 212         case EXPR_BINOP: {
 213                 char tmp[10];
 214                 struct expression *array_expr;
 215
 216                 *complicated = 1;
 217                 array_expr = get_array_expr(expr);
 218                 if (array_expr) {
 219                         __get_variable_from_expr(sym_ptr, buf, array_expr, len, complicated, no_parens);
 220                         append(buf, "[", len);
 221                 } else {
 222                         __get_variable_from_expr(sym_ptr, buf, expr->left, len, complicated, no_parens);
 223                         snprintf(tmp, sizeof(tmp), " %s ", show_special(expr->op));
 224                         append(buf, tmp, len);
 225                 }
 226                 __get_variable_from_expr(NULL, buf, expr->right, len, complicated, no_parens);
 227                 if (array_expr)
 228                         append(buf, "]", len);
 229                 return;
 230         }
 231         case EXPR_VALUE: {
 232                 char tmp[25];
 233
 234                 *complicated = 1;
 235                 snprintf(tmp, 25, "%lld", expr->value);
 236                 append(buf, tmp, len);
 237                 return;
 238         }
 239         case EXPR_STRING:
 240                 append(buf, "\"", len);
 241                 if (expr->string)
 242                         append(buf, expr->string->data, len);
 243                 append(buf, "\"", len);
 244                 return;
 245         case EXPR_CALL: {
 246                 struct expression *tmp;
 247                 int i;
 248
 249                 *complicated = 1;
 250                 __get_variable_from_expr(NULL, buf, expr->fn, len, complicated, no_parens);
 251                 append(buf, "(", len);
 252                 i = 0;
 253                 FOR_EACH_PTR(expr->args, tmp) {
 254                         if (i++)
 255                                 append(buf, ", ", len);
 256                         __get_variable_from_expr(NULL, buf, tmp, len, complicated, no_parens);
 257                 } END_FOR_EACH_PTR(tmp);
 258                 append(buf, ")", len);
 259                 return;
 260         }
 261         case EXPR_CAST:
 262         case EXPR_FORCE_CAST:
 263                 __get_variable_from_expr(sym_ptr, buf,
 264                                          expr->cast_expression, len,
 265                                          complicated, no_parens);
 266                 return;
 267         case EXPR_SIZEOF: {
 268                 int size;
 269                 char tmp[25];
 270
 271                 if (expr->cast_type && get_base_type(expr->cast_type)) {
 272                         size = type_bytes(get_base_type(expr->cast_type));
 273                         snprintf(tmp, 25, "%d", size);
 274                         append(buf, tmp, len);
 275                 }
 276                 return;
 277         }
 278         case EXPR_IDENTIFIER:
 279                 *complicated = 1;
 280                 if (expr->expr_ident)
 281                         append(buf, expr->expr_ident->name, len);
 282                 return;
 283         default:
 284                 *complicated = 1;
 285                 //printf("unknown type = %d\n", expr->type);
 286                 return;
 287         }
 288 }
 289
 290 /*
 291  * This is returns a stylized "c looking" representation of the
 292  * variable name.
 293  *
 294  * It uses the same buffer every time so you have to save the result
 295  * yourself if you want to keep it.
 296  *
 297  */
 298
 299 char *expr_to_str_sym(struct expression *expr, struct symbol **sym_ptr)
 300 {
 301         static char var_name[VAR_LEN];
 302         int complicated = 0;
 303
 304         if (sym_ptr)
 305                 *sym_ptr = NULL;
 306         var_name[0] = '\0';
 307
 308         if (!expr)
 309                 return NULL;
 310         __get_variable_from_expr(sym_ptr, var_name, expr, sizeof(var_name),
 311                                  &complicated, 0);
 312         if (complicated < 2)
 313                 return alloc_string(var_name);
 314         else
 315                 return NULL;
 316 }
 317
 318 char *expr_to_str(struct expression *expr)
 319 {
 320         return expr_to_str_sym(expr, NULL);
 321 }
 322
 323 /*
 324  * get_variable_from_expr_simple() only returns simple variables.
 325  * If it's a complicated variable like a->foo[x] instead of just 'a->foo'
 326  * then it returns NULL.
 327  */
 328 char *expr_to_var_sym(struct expression *expr,
 329                                     struct symbol **sym_ptr)
 330 {
 331         static char var_name[VAR_LEN];
 332         int complicated = 0;
 333
 334         if (sym_ptr)
 335                 *sym_ptr = NULL;
 336         var_name[0] = '\0';
 337
 338         if (!expr)
 339                 return NULL;
 340         expr = strip_expr(expr);
 341         __get_variable_from_expr(sym_ptr, var_name, expr, sizeof(var_name),
 342                                  &complicated, 1);
 343
 344         if (complicated) {
 345                 if (sym_ptr)
 346                         *sym_ptr = NULL;
 347                 return NULL;
 348         }
 349         return alloc_string(var_name);
 350 }
 351
 352 char *expr_to_var(struct expression *expr)
 353 {
 354         return expr_to_var_sym(expr, NULL);
 355 }
 356
 357 struct symbol *expr_to_sym(struct expression *expr)
 358 {
 359         struct symbol *sym;
 360         char *name;
 361
 362         name = expr_to_var_sym(expr, &sym);
 363         free_string(name);
 364         return sym;
 365 }
 366
 367 int get_complication_score(struct expression *expr)
 368 {
 369         int score = 0;
 370
 371         expr = strip_expr(expr);
 372
 373         /*
 374          * Don't forget to keep get_complication_score() and store_all_links()
 375          * in sync.
 376          *
 377          */
 378
 379         switch (expr->type) {
 380         case EXPR_CALL:
 381                 return 999;
 382         case EXPR_COMPARE:
 383         case EXPR_BINOP:
 384                 score += get_complication_score(expr->left);
 385                 score += get_complication_score(expr->right);
 386                 return score;
 387         case EXPR_SYMBOL:
 388                 if (is_local_variable(expr))
 389                         return 1;
 390                 return 999;
 391         case EXPR_PREOP:
 392                 if (expr->op == '*')
 393                         return score + get_complication_score(expr->unop);
 394                 return 999;
 395         case EXPR_DEREF:
 396                 return score + get_complication_score(expr->deref);
 397         case EXPR_VALUE:
 398                 return 0;
 399         default:
 400                 return 999;
 401         }
 402 }
 403
 404 char *expr_to_chunk_helper(struct expression *expr, struct symbol **sym, struct var_sym_list **vsl)
 405 {
 406         char *name;
 407         struct symbol *tmp;
 408         int score;
 409
 410         if (vsl)
 411                 *vsl = NULL;
 412         if (sym)
 413                 *sym = NULL;
 414
 415         expr = strip_parens(expr);
 416         if (!expr)
 417                 return NULL;
 418
 419         name = expr_to_var_sym(expr, &tmp);
 420         if (name && tmp) {
 421                 if (sym)
 422                         *sym = tmp;
 423                 if (vsl)
 424                         *vsl = expr_to_vsl(expr);
 425                 return name;
 426         }
 427         free_string(name);
 428
 429         score = get_complication_score(expr);
 430         if (score <= 0 || score > 2)
 431                 return NULL;
 432
 433         if (vsl) {
 434                 *vsl = expr_to_vsl(expr);
 435                 if (!*vsl)
 436                         return NULL;
 437         }
 438
 439         return expr_to_str(expr);
 440 }
 441
 442 char *expr_to_known_chunk_sym(struct expression *expr, struct symbol **sym)
 443 {
 444         return expr_to_chunk_helper(expr, sym, NULL);
 445 }
 446
 447 char *expr_to_chunk_sym_vsl(struct expression *expr, struct symbol **sym, struct var_sym_list **vsl)
 448 {
 449         return expr_to_chunk_helper(expr, sym, vsl);
 450 }
 451
 452 int sym_name_is(const char *name, struct expression *expr)
 453 {
 454         if (!expr)
 455                 return 0;
 456         if (expr->type != EXPR_SYMBOL)
 457                 return 0;
 458         if (!strcmp(expr->symbol_name->name, name))
 459                 return 1;
 460         return 0;
 461 }
 462
 463 int is_zero(struct expression *expr)
 464 {
 465         sval_t sval;
 466
 467         if (get_value(expr, &sval) && sval.value == 0)
 468                 return 1;
 469         return 0;
 470 }
 471
 472 int is_array(struct expression *expr)
 473 {
 474         struct symbol *type;
 475
 476         expr = strip_expr(expr);
 477         if (!expr)
 478                 return 0;
 479
 480         if (expr->type == EXPR_PREOP && expr->op == '*') {
 481                 expr = strip_expr(expr->unop);
 482                 if (expr->type == EXPR_BINOP && expr->op == '+')
 483                         return 1;
 484         }
 485
 486         if (expr->type != EXPR_BINOP || expr->op != '+')
 487                 return 0;
 488
 489         type = get_type(expr->left);
 490         if (!type || type->type != SYM_ARRAY)
 491                 return 0;
 492
 493         return 1;
 494 }
 495
 496 struct expression *get_array_base(struct expression *expr)
 497 {
 498         if (!is_array(expr))
 499                 return NULL;
 500         expr = strip_expr(expr);
 501         if (expr->type == EXPR_PREOP && expr->op == '*')
 502                 expr = strip_expr(expr->unop);
 503         if (expr->type != EXPR_BINOP || expr->op != '+')
 504                 return NULL;
 505         return strip_parens(expr->left);
 506 }
 507
 508 struct expression *get_array_offset(struct expression *expr)
 509 {
 510         if (!is_array(expr))
 511                 return NULL;
 512         expr = strip_expr(expr);
 513         if (expr->type == EXPR_PREOP && expr->op == '*')
 514                 expr = strip_expr(expr->unop);
 515         if (expr->type != EXPR_BINOP || expr->op != '+')
 516                 return NULL;
 517         return strip_parens(expr->right);
 518 }
 519
 520 const char *show_state(struct smatch_state *state)
 521 {
 522         if (!state)
 523                 return NULL;
 524         return state->name;
 525 }
 526
 527 struct statement *get_expression_statement(struct expression *expr)
 528 {
 529         /* What are those things called? if (({....; ret;})) { ...*/
 530
 531         if (expr->type != EXPR_PREOP)
 532                 return NULL;
 533         if (expr->op != '(')
 534                 return NULL;
 535         if (expr->unop->type != EXPR_STATEMENT)
 536                 return NULL;
 537         if (expr->unop->statement->type != STMT_COMPOUND)
 538                 return NULL;
 539         return expr->unop->statement;
 540 }
 541
 542 struct expression *strip_parens(struct expression *expr)
 543 {
 544         if (!expr)
 545                 return NULL;
 546
 547         if (expr->type == EXPR_PREOP) {
 548                 if (expr->op == '(' && expr->unop->type == EXPR_STATEMENT &&
 549                         expr->unop->statement->type == STMT_COMPOUND)
 550                         return expr;
 551                 if (expr->op == '(')
 552                         return strip_parens(expr->unop);
 553         }
 554         return expr;
 555 }
 556
 557 struct expression *strip_expr(struct expression *expr)
 558 {
 559         if (!expr)
 560                 return NULL;
 561
 562         switch (expr->type) {
 563         case EXPR_FORCE_CAST:
 564         case EXPR_CAST:
 565                 return strip_expr(expr->cast_expression);
 566         case EXPR_PREOP: {
 567                 struct expression *unop;
 568
 569                 if (expr->op == '(' && expr->unop->type == EXPR_STATEMENT &&
 570                         expr->unop->statement->type == STMT_COMPOUND)
 571                         return expr;
 572
 573                 unop = strip_expr(expr->unop);
 574
 575                 if (expr->op == '*' &&
 576                     unop->type == EXPR_PREOP && unop->op == '&') {
 577                         struct symbol *type = get_type(unop->unop);
 578
 579                         if (type && type->type == SYM_ARRAY)
 580                                 return expr;
 581                         return strip_expr(unop->unop);
 582                 }
 583
 584                 if (expr->op == '(')
 585                         return unop;
 586
 587                 return expr;
 588         }
 589         case EXPR_CONDITIONAL:
 590                 if (known_condition_true(expr->conditional)) {
 591                         if (expr->cond_true)
 592                                 return strip_expr(expr->cond_true);
 593                         return strip_expr(expr->conditional);
 594                 }
 595                 if (known_condition_false(expr->conditional))
 596                         return strip_expr(expr->cond_false);
 597                 return expr;
 598         case EXPR_CALL:
 599                 if (sym_name_is("__builtin_expect", expr->fn)) {
 600                         expr = get_argument_from_call_expr(expr->args, 0);
 601                         return strip_expr(expr);
 602                 }
 603                 return expr;
 604         }
 605         return expr;
 606 }
 607
 608 static void delete_state_tracker(struct tracker *t)
 609 {
 610         delete_state(t->owner, t->name, t->sym);
 611         __free_tracker(t);
 612 }
 613
 614 void scoped_state(int my_id, const char *name, struct symbol *sym)
 615 {
 616         struct tracker *t;
 617
 618         t = alloc_tracker(my_id, name, sym);
 619         add_scope_hook((scope_hook *)&delete_state_tracker, t);
 620 }
 621
 622 int is_error_return(struct expression *expr)
 623 {
 624         struct symbol *cur_func = cur_func_sym;
 625         sval_t sval;
 626
 627         if (!expr)
 628                 return 0;
 629         if (cur_func->type != SYM_NODE)
 630                 return 0;
 631         cur_func = get_base_type(cur_func);
 632         if (cur_func->type != SYM_FN)
 633                 return 0;
 634         cur_func = get_base_type(cur_func);
 635         if (cur_func == &void_ctype)
 636                 return 0;
 637         if (!get_implied_value(expr, &sval))
 638                 return 0;
 639         if (sval.value < 0)
 640                 return 1;
 641         if (cur_func->type == SYM_PTR && sval.value == 0)
 642                 return 1;
 643         return 0;
 644 }
 645
 646 int getting_address(void)
 647 {
 648         struct expression *tmp;
 649         int i = 0;
 650         int dot_ops = 0;
 651
 652         FOR_EACH_PTR_REVERSE(big_expression_stack, tmp) {
 653                 if (!i++)
 654                         continue;
 655                 if (tmp->type == EXPR_PREOP && tmp->op == '(')
 656                         continue;
 657                 if (tmp->op == '.' && !dot_ops++)
 658                         continue;
 659                 if (tmp->op == '&')
 660                         return 1;
 661                 return 0;
 662         } END_FOR_EACH_PTR_REVERSE(tmp);
 663         return 0;
 664 }
 665
 666 char *get_member_name(struct expression *expr)
 667 {
 668         char buf[256];
 669         struct symbol *sym;
 670
 671         expr = strip_expr(expr);
 672         if (expr->type != EXPR_DEREF)
 673                 return NULL;
 674         if (!expr->member)
 675                 return NULL;
 676
 677         sym = get_type(expr->deref);
 678         if (!sym)
 679                 return NULL;
 680         if (sym->type == SYM_UNION) {
 681                 sym = expr_to_sym(expr->deref);
 682                 sym = get_real_base_type(sym);
 683                 if (sym && sym->type == SYM_PTR)
 684                         sym = get_real_base_type(sym);
 685                 if (!sym || !sym->ident) {
 686                         snprintf(buf, sizeof(buf), "(union hack)->%s", expr->member->name);
 687                         return alloc_string(buf);
 688                 }
 689         }
 690         if (!sym->ident)
 691                 return NULL;
 692         snprintf(buf, sizeof(buf), "(struct %s)->%s", sym->ident->name, expr->member->name);
 693         return alloc_string(buf);
 694 }
 695
 696 int cmp_pos(struct position pos1, struct position pos2)
 697 {
 698         /* the stream position is ... */
 699         if (pos1.stream > pos2.stream)
 700                 return -1;
 701         if (pos1.stream < pos2.stream)
 702                 return 1;
 703
 704         if (pos1.line < pos2.line)
 705                 return -1;
 706         if (pos1.line > pos2.line)
 707                 return 1;
 708
 709         if (pos1.pos < pos2.pos)
 710                 return -1;
 711         if (pos1.pos > pos2.pos)
 712                 return 1;
 713
 714         return 0;
 715 }
 716
 717 int positions_eq(struct position pos1, struct position pos2)
 718 {
 719         if (pos1.line != pos2.line)
 720                 return 0;
 721         if (pos1.pos != pos2.pos)
 722                 return 0;
 723         if (pos1.stream != pos2.stream)
 724                 return 0;
 725         return 1;
 726 }
 727
 728 struct statement *get_current_statement(void)
 729 {
 730         struct statement *prev, *tmp;
 731
 732         prev = last_ptr_list((struct ptr_list *)big_statement_stack);
 733
 734         if (!prev || !get_macro_name(prev->pos))
 735                 return prev;
 736
 737         FOR_EACH_PTR_REVERSE(big_statement_stack, tmp) {
 738                 if (positions_eq(tmp->pos, prev->pos))
 739                         continue;
 740                 if (prev->pos.line > tmp->pos.line)
 741                         return prev;
 742                 return tmp;
 743         } END_FOR_EACH_PTR_REVERSE(tmp);
 744         return prev;
 745 }
 746
 747 struct statement *get_prev_statement(void)
 748 {
 749         struct statement *tmp;
 750         int i;
 751
 752         i = 0;
 753         FOR_EACH_PTR_REVERSE(big_statement_stack, tmp) {
 754                 if (i++ == 1)
 755                         return tmp;
 756         } END_FOR_EACH_PTR_REVERSE(tmp);
 757         return NULL;
 758 }
 759
 760 int get_param_num_from_sym(struct symbol *sym)
 761 {
 762         struct symbol *tmp;
 763         int i;
 764
 765         if (!cur_func_sym)
 766                 return -1;
 767
 768         i = 0;
 769         FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, tmp) {
 770                 if (tmp == sym)
 771                         return i;
 772                 i++;
 773         } END_FOR_EACH_PTR(tmp);
 774         return -1;
 775 }
 776
 777 int get_param_num(struct expression *expr)
 778 {
 779         struct symbol *sym;
 780         char *name;
 781
 782         if (!cur_func_sym)
 783                 return -1;
 784         name = expr_to_var_sym(expr, &sym);
 785         free_string(name);
 786         if (!sym)
 787                 return -1;
 788         return get_param_num_from_sym(sym);
 789 }
 790
 791 int ms_since(struct timeval *start)
 792 {
 793         struct timeval end;
 794         double diff;
 795
 796         gettimeofday(&end, NULL);
 797         diff = (end.tv_sec - start->tv_sec) * 1000.0;
 798         diff += (end.tv_usec - start->tv_usec) / 1000.0;
 799         return (int)diff;
 800 }
 801
 802 int parent_is_gone_var_sym(const char *name, struct symbol *sym)
 803 {
 804         if (!name || !sym)
 805                 return 0;
 806
 807         if (parent_is_null_var_sym(name, sym) ||
 808             parent_is_free_var_sym(name, sym))
 809                 return 1;
 810         return 0;
 811 }
 812
 813 int parent_is_gone(struct expression *expr)
 814 {
 815         struct symbol *sym;
 816         char *var;
 817         int ret = 0;
 818
 819         expr = strip_expr(expr);
 820         var = expr_to_var_sym(expr, &sym);
 821         if (!var || !sym)
 822                 goto free;
 823         ret = parent_is_gone_var_sym(var, sym);
 824 free:
 825         free_string(var);
 826         return ret;
 827 }
 828
 829 int invert_op(int op)
 830 {
 831         switch (op) {
 832         case '*':
 833                 return '/';
 834         case '/':
 835                 return '*';
 836         case '+':
 837                 return '-';
 838         case '-':
 839                 return '+';
 840         case SPECIAL_LEFTSHIFT:
 841                 return SPECIAL_RIGHTSHIFT;
 842         case SPECIAL_RIGHTSHIFT:
 843                 return SPECIAL_LEFTSHIFT;
 844         }
 845         return 0;
 846 }
 847
 848 int expr_equiv(struct expression *one, struct expression *two)
 849 {
 850         struct symbol *one_sym, *two_sym;
 851         char *one_name = NULL;
 852         char *two_name = NULL;
 853         int ret = 0;
 854
 855         if (!one || !two)
 856                 return 0;
 857         if (one->type != two->type)
 858                 return 0;
 859
 860         one_name = expr_to_str_sym(one, &one_sym);
 861         if (!one_name || !one_sym)
 862                 goto free;
 863         two_name = expr_to_str_sym(two, &two_sym);
 864         if (!two_name || !two_sym)
 865                 goto free;
 866         if (one_sym != two_sym)
 867                 goto free;
 868         if (strcmp(one_name, two_name) == 0)
 869                 ret = 1;
 870 free:
 871         free_string(one_name);
 872         free_string(two_name);
 873         return ret;
 874 }
 875