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                         }
 143                 }
 144
 145                 __get_variable_from_expr(sym_ptr, buf, deref, len, complicated, no_parens);
 146
 147                 if (op == '*')
 148                         append(buf, "->", len);
 149                 else
 150                         append(buf, ".", len);
 151
 152                 if (expr->member)
 153                         append(buf, expr->member->name, len);
 154                 else
 155                         append(buf, "unknown_member", len);
 156
 157                 return;
 158         }
 159         case EXPR_SYMBOL:
 160                 if (expr->symbol_name)
 161                         append(buf, expr->symbol_name->name, len);
 162                 if (sym_ptr) {
 163                         if (*sym_ptr)
 164                                 *complicated = 1;
 165                         *sym_ptr = expr->symbol;
 166                 }
 167                 return;
 168         case EXPR_PREOP: {
 169                 const char *tmp;
 170
 171                 if (get_expression_statement(expr)) {
 172                         *complicated = 2;
 173                         return;
 174                 }
 175
 176                 if (expr->op == '(') {
 177                         if (!no_parens)
 178                                 append(buf, "(", len);
 179                 } else if (expr->op != '*' || !get_array_expr(expr->unop)) {
 180                         tmp = show_special(expr->op);
 181                         append(buf, tmp, len);
 182                 }
 183                 __get_variable_from_expr(sym_ptr, buf, expr->unop,
 184                                                  len, complicated, no_parens);
 185
 186                 if (expr->op == '(' && !no_parens)
 187                         append(buf, ")", len);
 188
 189                 if (expr->op == SPECIAL_DECREMENT ||
 190                                 expr->op == SPECIAL_INCREMENT)
 191                         *complicated = 1;
 192
 193                 return;
 194         }
 195         case EXPR_POSTOP: {
 196                 const char *tmp;
 197
 198                 __get_variable_from_expr(sym_ptr, buf, expr->unop,
 199                                                  len, complicated, no_parens);
 200                 tmp = show_special(expr->op);
 201                 append(buf, tmp, len);
 202
 203                 if (expr->op == SPECIAL_DECREMENT || expr->op == SPECIAL_INCREMENT)
 204                         *complicated = 1;
 205                 return;
 206         }
 207         case EXPR_ASSIGNMENT:
 208         case EXPR_COMPARE:
 209         case EXPR_LOGICAL:
 210         case EXPR_BINOP: {
 211                 char tmp[10];
 212                 struct expression *array_expr;
 213
 214                 *complicated = 1;
 215                 array_expr = get_array_expr(expr);
 216                 if (array_expr) {
 217                         __get_variable_from_expr(sym_ptr, buf, array_expr, len, complicated, no_parens);
 218                         append(buf, "[", len);
 219                 } else {
 220                         __get_variable_from_expr(sym_ptr, buf, expr->left, len, complicated, no_parens);
 221                         snprintf(tmp, sizeof(tmp), " %s ", show_special(expr->op));
 222                         append(buf, tmp, len);
 223                 }
 224                 __get_variable_from_expr(NULL, buf, expr->right, len, complicated, no_parens);
 225                 if (array_expr)
 226                         append(buf, "]", len);
 227                 return;
 228         }
 229         case EXPR_VALUE: {
 230                 char tmp[25];
 231
 232                 *complicated = 1;
 233                 snprintf(tmp, 25, "%lld", expr->value);
 234                 append(buf, tmp, len);
 235                 return;
 236         }
 237         case EXPR_STRING:
 238                 append(buf, "\"", len);
 239                 if (expr->string)
 240                         append(buf, expr->string->data, len);
 241                 append(buf, "\"", len);
 242                 return;
 243         case EXPR_CALL: {
 244                 struct expression *tmp;
 245                 int i;
 246
 247                 *complicated = 1;
 248                 __get_variable_from_expr(NULL, buf, expr->fn, len, complicated, no_parens);
 249                 append(buf, "(", len);
 250                 i = 0;
 251                 FOR_EACH_PTR(expr->args, tmp) {
 252                         if (i++)
 253                                 append(buf, ", ", len);
 254                         __get_variable_from_expr(NULL, buf, tmp, len, complicated, no_parens);
 255                 } END_FOR_EACH_PTR(tmp);
 256                 append(buf, ")", len);
 257                 return;
 258         }
 259         case EXPR_CAST:
 260         case EXPR_FORCE_CAST:
 261                 __get_variable_from_expr(sym_ptr, buf,
 262                                          expr->cast_expression, len,
 263                                          complicated, no_parens);
 264                 return;
 265         case EXPR_SIZEOF: {
 266                 int size;
 267                 char tmp[25];
 268
 269                 if (expr->cast_type && get_base_type(expr->cast_type)) {
 270                         size = type_bytes(get_base_type(expr->cast_type));
 271                         snprintf(tmp, 25, "%d", size);
 272                         append(buf, tmp, len);
 273                 }
 274                 return;
 275         }
 276         case EXPR_IDENTIFIER:
 277                 *complicated = 1;
 278                 if (expr->expr_ident)
 279                         append(buf, expr->expr_ident->name, len);
 280                 return;
 281         default:
 282                 *complicated = 1;
 283                 //printf("unknown type = %d\n", expr->type);
 284                 return;
 285         }
 286 }
 287
 288 /*
 289  * This is returns a stylized "c looking" representation of the
 290  * variable name.
 291  *
 292  * It uses the same buffer every time so you have to save the result
 293  * yourself if you want to keep it.
 294  *
 295  */
 296
 297 char *expr_to_str_sym(struct expression *expr, struct symbol **sym_ptr)
 298 {
 299         static char var_name[VAR_LEN];
 300         int complicated = 0;
 301
 302         if (sym_ptr)
 303                 *sym_ptr = NULL;
 304         var_name[0] = '\0';
 305
 306         if (!expr)
 307                 return NULL;
 308         __get_variable_from_expr(sym_ptr, var_name, expr, sizeof(var_name),
 309                                  &complicated, 0);
 310         if (complicated < 2)
 311                 return alloc_string(var_name);
 312         else
 313                 return NULL;
 314 }
 315
 316 char *expr_to_str(struct expression *expr)
 317 {
 318         return expr_to_str_sym(expr, NULL);
 319 }
 320
 321 /*
 322  * get_variable_from_expr_simple() only returns simple variables.
 323  * If it's a complicated variable like a->foo[x] instead of just 'a->foo'
 324  * then it returns NULL.
 325  */
 326 char *expr_to_var_sym(struct expression *expr,
 327                                     struct symbol **sym_ptr)
 328 {
 329         static char var_name[VAR_LEN];
 330         int complicated = 0;
 331
 332         if (sym_ptr)
 333                 *sym_ptr = NULL;
 334         var_name[0] = '\0';
 335
 336         if (!expr)
 337                 return NULL;
 338         expr = strip_expr(expr);
 339         __get_variable_from_expr(sym_ptr, var_name, expr, sizeof(var_name),
 340                                  &complicated, 1);
 341
 342         if (complicated) {
 343                 if (sym_ptr)
 344                         *sym_ptr = NULL;
 345                 return NULL;
 346         }
 347         return alloc_string(var_name);
 348 }
 349
 350 char *expr_to_var(struct expression *expr)
 351 {
 352         return expr_to_var_sym(expr, NULL);
 353 }
 354
 355 struct symbol *expr_to_sym(struct expression *expr)
 356 {
 357         struct symbol *sym;
 358         char *name;
 359
 360         name = expr_to_var_sym(expr, &sym);
 361         free_string(name);
 362         return sym;
 363 }
 364
 365 char *expr_to_chunk_helper(struct expression *expr, struct symbol **sym, struct var_sym_list **vsl)
 366 {
 367         char *name, *left_name, *right_name;
 368         struct symbol *tmp, *left_sym, *right_sym;
 369         char buf[128];
 370
 371         if (vsl)
 372                 *vsl = NULL;
 373
 374         expr = strip_parens(expr);
 375         if (!expr)
 376                 return NULL;
 377         if (sym)
 378                 *sym = NULL;
 379
 380         name = expr_to_var_sym(expr, &tmp);
 381         if (name && tmp) {
 382                 if (sym)
 383                         *sym = tmp;
 384                 if (vsl)
 385                         *vsl = expr_to_vsl(expr);
 386                 return name;
 387         }
 388         free_string(name);
 389
 390         if (expr->type != EXPR_BINOP)
 391                 return NULL;
 392         if (expr->op != '-' && expr->op != '+')
 393                 return NULL;
 394
 395         if (vsl) {
 396                 *vsl = expr_to_vsl(expr);
 397                 if (!*vsl)
 398                         return NULL;
 399         }
 400
 401         left_name = expr_to_var_sym(expr->left, &left_sym);
 402         if (!left_name || !left_sym)
 403                 return NULL;
 404         right_name = expr_to_var_sym(expr->right, &right_sym);
 405         if (!right_name || !right_sym) {
 406                 free_string(left_name);
 407                 return NULL;
 408         }
 409
 410         if (expr->op == '+') {
 411                 if (strcmp(left_name, right_name) > 0) {
 412                         char *tmp_name;
 413
 414                         tmp = left_sym;
 415                         left_sym = right_sym;
 416                         right_sym = tmp;
 417
 418                         tmp_name = left_name;
 419                         left_name = right_name;
 420                         right_name = tmp_name;
 421                 }
 422         }
 423
 424         snprintf(buf, sizeof(buf), "%s %s %s", left_name, show_special(expr->op), right_name);
 425         *sym = left_sym;
 426         free_string(left_name);
 427         free_string(right_name);
 428         return alloc_string(buf);
 429 }
 430
 431 char *expr_to_known_chunk_sym(struct expression *expr, struct symbol **sym)
 432 {
 433         return expr_to_chunk_helper(expr, sym, NULL);
 434 }
 435
 436 char *expr_to_chunk_sym_vsl(struct expression *expr, struct symbol **sym, struct var_sym_list **vsl)
 437 {
 438         return expr_to_chunk_helper(expr, sym, vsl);
 439 }
 440
 441 int sym_name_is(const char *name, struct expression *expr)
 442 {
 443         if (!expr)
 444                 return 0;
 445         if (expr->type != EXPR_SYMBOL)
 446                 return 0;
 447         if (!strcmp(expr->symbol_name->name, name))
 448                 return 1;
 449         return 0;
 450 }
 451
 452 int is_zero(struct expression *expr)
 453 {
 454         sval_t sval;
 455
 456         if (get_value(expr, &sval) && sval.value == 0)
 457                 return 1;
 458         return 0;
 459 }
 460
 461 int is_array(struct expression *expr)
 462 {
 463         struct symbol *type;
 464
 465         expr = strip_expr(expr);
 466         if (!expr)
 467                 return 0;
 468
 469         if (expr->type == EXPR_PREOP && expr->op == '*') {
 470                 expr = strip_expr(expr->unop);
 471                 if (expr->type == EXPR_BINOP && expr->op == '+')
 472                         return 1;
 473         }
 474
 475         if (expr->type != EXPR_BINOP || expr->op != '+')
 476                 return 0;
 477
 478         type = get_type(expr->left);
 479         if (!type || type->type != SYM_ARRAY)
 480                 return 0;
 481
 482         return 1;
 483 }
 484
 485 struct expression *get_array_base(struct expression *expr)
 486 {
 487         if (!is_array(expr))
 488                 return NULL;
 489         expr = strip_expr(expr);
 490         if (expr->type == EXPR_PREOP && expr->op == '*')
 491                 expr = strip_expr(expr->unop);
 492         if (expr->type != EXPR_BINOP || expr->op != '+')
 493                 return NULL;
 494         return strip_parens(expr->left);
 495 }
 496
 497 struct expression *get_array_offset(struct expression *expr)
 498 {
 499         if (!is_array(expr))
 500                 return NULL;
 501         expr = strip_expr(expr);
 502         if (expr->type == EXPR_PREOP && expr->op == '*')
 503                 expr = strip_expr(expr->unop);
 504         if (expr->type != EXPR_BINOP || expr->op != '+')
 505                 return NULL;
 506         return strip_parens(expr->right);
 507 }
 508
 509 const char *show_state(struct smatch_state *state)
 510 {
 511         if (!state)
 512                 return NULL;
 513         return state->name;
 514 }
 515
 516 struct statement *get_expression_statement(struct expression *expr)
 517 {
 518         /* What are those things called? if (({....; ret;})) { ...*/
 519
 520         if (expr->type != EXPR_PREOP)
 521                 return NULL;
 522         if (expr->op != '(')
 523                 return NULL;
 524         if (expr->unop->type != EXPR_STATEMENT)
 525                 return NULL;
 526         if (expr->unop->statement->type != STMT_COMPOUND)
 527                 return NULL;
 528         return expr->unop->statement;
 529 }
 530
 531 struct expression *strip_parens(struct expression *expr)
 532 {
 533         if (!expr)
 534                 return NULL;
 535
 536         if (expr->type == EXPR_PREOP) {
 537                 if (expr->op == '(' && expr->unop->type == EXPR_STATEMENT &&
 538                         expr->unop->statement->type == STMT_COMPOUND)
 539                         return expr;
 540                 if (expr->op == '(')
 541                         return strip_parens(expr->unop);
 542         }
 543         return expr;
 544 }
 545
 546 struct expression *strip_expr(struct expression *expr)
 547 {
 548         if (!expr)
 549                 return NULL;
 550
 551         switch (expr->type) {
 552         case EXPR_FORCE_CAST:
 553         case EXPR_CAST:
 554                 return strip_expr(expr->cast_expression);
 555         case EXPR_PREOP: {
 556                 struct expression *unop;
 557
 558                 if (expr->op == '(' && expr->unop->type == EXPR_STATEMENT &&
 559                         expr->unop->statement->type == STMT_COMPOUND)
 560                         return expr;
 561
 562                 unop = strip_expr(expr->unop);
 563
 564                 if (expr->op == '*' &&
 565                     unop->type == EXPR_PREOP && unop->op == '&') {
 566                         struct symbol *type = get_type(unop->unop);
 567
 568                         if (type && type->type == SYM_ARRAY)
 569                                 return expr;
 570                         return strip_expr(unop->unop);
 571                 }
 572
 573                 if (expr->op == '(')
 574                         return unop;
 575
 576                 return expr;
 577         }
 578         case EXPR_CONDITIONAL:
 579                 if (known_condition_true(expr->conditional)) {
 580                         if (expr->cond_true)
 581                                 return strip_expr(expr->cond_true);
 582                         return strip_expr(expr->conditional);
 583                 }
 584                 if (known_condition_false(expr->conditional))
 585                         return strip_expr(expr->cond_false);
 586                 return expr;
 587         case EXPR_CALL:
 588                 if (sym_name_is("__builtin_expect", expr->fn)) {
 589                         expr = get_argument_from_call_expr(expr->args, 0);
 590                         return strip_expr(expr);
 591                 }
 592                 return expr;
 593         }
 594         return expr;
 595 }
 596
 597 static void delete_state_tracker(struct tracker *t)
 598 {
 599         delete_state(t->owner, t->name, t->sym);
 600         __free_tracker(t);
 601 }
 602
 603 void scoped_state(int my_id, const char *name, struct symbol *sym)
 604 {
 605         struct tracker *t;
 606
 607         t = alloc_tracker(my_id, name, sym);
 608         add_scope_hook((scope_hook *)&delete_state_tracker, t);
 609 }
 610
 611 int is_error_return(struct expression *expr)
 612 {
 613         struct symbol *cur_func = cur_func_sym;
 614         sval_t sval;
 615
 616         if (!expr)
 617                 return 0;
 618         if (cur_func->type != SYM_NODE)
 619                 return 0;
 620         cur_func = get_base_type(cur_func);
 621         if (cur_func->type != SYM_FN)
 622                 return 0;
 623         cur_func = get_base_type(cur_func);
 624         if (cur_func == &void_ctype)
 625                 return 0;
 626         if (!get_implied_value(expr, &sval))
 627                 return 0;
 628         if (sval.value < 0)
 629                 return 1;
 630         if (cur_func->type == SYM_PTR && sval.value == 0)
 631                 return 1;
 632         return 0;
 633 }
 634
 635 int getting_address(void)
 636 {
 637         struct expression *tmp;
 638         int i = 0;
 639         int dot_ops = 0;
 640
 641         FOR_EACH_PTR_REVERSE(big_expression_stack, tmp) {
 642                 if (!i++)
 643                         continue;
 644                 if (tmp->type == EXPR_PREOP && tmp->op == '(')
 645                         continue;
 646                 if (tmp->op == '.' && !dot_ops++)
 647                         continue;
 648                 if (tmp->op == '&')
 649                         return 1;
 650                 return 0;
 651         } END_FOR_EACH_PTR_REVERSE(tmp);
 652         return 0;
 653 }
 654
 655 char *get_member_name(struct expression *expr)
 656 {
 657         char buf[256];
 658         struct symbol *sym;
 659
 660         expr = strip_expr(expr);
 661         if (expr->type != EXPR_DEREF)
 662                 return NULL;
 663         if (!expr->member)
 664                 return NULL;
 665
 666         sym = get_type(expr->deref);
 667         if (!sym)
 668                 return NULL;
 669         if (sym->type == SYM_UNION) {
 670                 sym = expr_to_sym(expr->deref);
 671                 sym = get_real_base_type(sym);
 672                 if (sym && sym->type == SYM_PTR)
 673                         sym = get_real_base_type(sym);
 674                 if (!sym || !sym->ident) {
 675                         snprintf(buf, sizeof(buf), "(union hack)->%s", expr->member->name);
 676                         return alloc_string(buf);
 677                 }
 678         }
 679         if (!sym->ident)
 680                 return NULL;
 681         snprintf(buf, sizeof(buf), "(struct %s)->%s", sym->ident->name, expr->member->name);
 682         return alloc_string(buf);
 683 }
 684
 685 int cmp_pos(struct position pos1, struct position pos2)
 686 {
 687         /* the stream position is ... */
 688         if (pos1.stream > pos2.stream)
 689                 return -1;
 690         if (pos1.stream < pos2.stream)
 691                 return 1;
 692
 693         if (pos1.line < pos2.line)
 694                 return -1;
 695         if (pos1.line > pos2.line)
 696                 return 1;
 697
 698         if (pos1.pos < pos2.pos)
 699                 return -1;
 700         if (pos1.pos > pos2.pos)
 701                 return 1;
 702
 703         return 0;
 704 }
 705
 706 int positions_eq(struct position pos1, struct position pos2)
 707 {
 708         if (pos1.line != pos2.line)
 709                 return 0;
 710         if (pos1.pos != pos2.pos)
 711                 return 0;
 712         if (pos1.stream != pos2.stream)
 713                 return 0;
 714         return 1;
 715 }
 716
 717 struct statement *get_current_statement(void)
 718 {
 719         struct statement *prev, *tmp;
 720
 721         prev = last_ptr_list((struct ptr_list *)big_statement_stack);
 722
 723         if (!prev || !get_macro_name(prev->pos))
 724                 return prev;
 725
 726         FOR_EACH_PTR_REVERSE(big_statement_stack, tmp) {
 727                 if (positions_eq(tmp->pos, prev->pos))
 728                         continue;
 729                 if (prev->pos.line > tmp->pos.line)
 730                         return prev;
 731                 return tmp;
 732         } END_FOR_EACH_PTR_REVERSE(tmp);
 733         return prev;
 734 }
 735
 736 struct statement *get_prev_statement(void)
 737 {
 738         struct statement *tmp;
 739         int i;
 740
 741         i = 0;
 742         FOR_EACH_PTR_REVERSE(big_statement_stack, tmp) {
 743                 if (i++ == 1)
 744                         return tmp;
 745         } END_FOR_EACH_PTR_REVERSE(tmp);
 746         return NULL;
 747 }
 748
 749 int get_param_num_from_sym(struct symbol *sym)
 750 {
 751         struct symbol *tmp;
 752         int i;
 753
 754         if (!cur_func_sym)
 755                 return -1;
 756
 757         i = 0;
 758         FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, tmp) {
 759                 if (tmp == sym)
 760                         return i;
 761                 i++;
 762         } END_FOR_EACH_PTR(tmp);
 763         return -1;
 764 }
 765
 766 int get_param_num(struct expression *expr)
 767 {
 768         struct symbol *sym;
 769         char *name;
 770
 771         if (!cur_func_sym)
 772                 return -1;
 773         name = expr_to_var_sym(expr, &sym);
 774         free_string(name);
 775         if (!sym)
 776                 return -1;
 777         return get_param_num_from_sym(sym);
 778 }
 779
 780 int ms_since(struct timeval *start)
 781 {
 782         struct timeval end;
 783         double diff;
 784
 785         gettimeofday(&end, NULL);
 786         diff = (end.tv_sec - start->tv_sec) * 1000.0;
 787         diff += (end.tv_usec - start->tv_usec) / 1000.0;
 788         return (int)diff;
 789 }
 790
 791 int parent_is_gone_var_sym(const char *name, struct symbol *sym)
 792 {
 793         if (!name || !sym)
 794                 return 0;
 795
 796         if (parent_is_null_var_sym(name, sym) ||
 797             parent_is_free_var_sym(name, sym))
 798                 return 1;
 799         return 0;
 800 }
 801
 802 int parent_is_gone(struct expression *expr)
 803 {
 804         struct symbol *sym;
 805         char *var;
 806         int ret = 0;
 807
 808         expr = strip_expr(expr);
 809         var = expr_to_var_sym(expr, &sym);
 810         if (!var || !sym)
 811                 goto free;
 812         ret = parent_is_gone_var_sym(var, sym);
 813 free:
 814         free_string(var);
 815         return ret;
 816 }
 817
 818 int invert_op(int op)
 819 {
 820         switch (op) {
 821         case '*':
 822                 return '/';
 823         case '/':
 824                 return '*';
 825         case '+':
 826                 return '-';
 827         case '-':
 828                 return '+';
 829         case SPECIAL_LEFTSHIFT:
 830                 return SPECIAL_RIGHTSHIFT;
 831         case SPECIAL_RIGHTSHIFT:
 832                 return SPECIAL_LEFTSHIFT;
 833         }
 834         return 0;
 835 }