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 #include "smatch_slist.h"
  28
  29 #define VAR_LEN 512
  30
  31 char *alloc_string(const char *str)
  32 {
  33         char *tmp;
  34
  35         if (!str)
  36                 return NULL;
  37         tmp = malloc(strlen(str) + 1);
  38         strcpy(tmp, str);
  39         return tmp;
  40 }
  41
  42 void free_string(char *str)
  43 {
  44         free(str);
  45 }
  46
  47 void remove_parens(char *str)
  48 {
  49         char *src, *dst;
  50
  51         dst = src = str;
  52         while (*src != '\0') {
  53                 if (*src == '(' || *src == ')') {
  54                         src++;
  55                         continue;
  56                 }
  57                 *dst++ = *src++;
  58         }
  59         *dst = *src;
  60 }
  61
  62 struct smatch_state *alloc_state_num(int num)
  63 {
  64         struct smatch_state *state;
  65         static char buff[256];
  66
  67         state = __alloc_smatch_state(0);
  68         snprintf(buff, 255, "%d", num);
  69         buff[255] = '\0';
  70         state->name = alloc_string(buff);
  71         state->data = INT_PTR(num);
  72         return state;
  73 }
  74
  75 struct smatch_state *alloc_state_str(const char *name)
  76 {
  77         struct smatch_state *state;
  78
  79         state = __alloc_smatch_state(0);
  80         state->name = alloc_string(name);
  81         return state;
  82 }
  83
  84 struct smatch_state *alloc_state_expr(struct expression *expr)
  85 {
  86         struct smatch_state *state;
  87         char *name;
  88
  89         state = __alloc_smatch_state(0);
  90         expr = strip_expr(expr);
  91         name = expr_to_str(expr);
  92         state->name = alloc_sname(name);
  93         free_string(name);
  94         state->data = expr;
  95         return state;
  96 }
  97
  98 void append(char *dest, const char *data, int buff_len)
  99 {
 100         strncat(dest, data, buff_len - strlen(dest) - 1);
 101 }
 102
 103 /*
 104  * If you have "foo(a, b, 1);" then use
 105  * get_argument_from_call_expr(expr, 0) to return the expression for
 106  * a.  Yes, it does start counting from 0.
 107  */
 108 struct expression *get_argument_from_call_expr(struct expression_list *args,
 109                                                int num)
 110 {
 111         struct expression *expr;
 112         int i = 0;
 113
 114         if (!args)
 115                 return NULL;
 116
 117         FOR_EACH_PTR(args, expr) {
 118                 if (i == num)
 119                         return expr;
 120                 i++;
 121         } END_FOR_EACH_PTR(expr);
 122         return NULL;
 123 }
 124
 125 static struct expression *get_array_expr(struct expression *expr)
 126 {
 127         struct symbol *type;
 128
 129         if (expr->type != EXPR_BINOP || expr->op != '+')
 130                 return NULL;
 131
 132         type = get_type(expr->left);
 133         if (!type || type->type != SYM_ARRAY)
 134                 return NULL;
 135         return expr->left;
 136 }
 137
 138 static void __get_variable_from_expr(struct symbol **sym_ptr, char *buf,
 139                                      struct expression *expr, int len,
 140                                      int *complicated, int no_parens)
 141 {
 142         switch (expr->type) {
 143         case EXPR_DEREF: {
 144                 struct expression *deref;
 145                 int op;
 146
 147                 deref = expr->deref;
 148                 op = deref->op;
 149                 if (op == '*') {
 150                         struct expression *unop = strip_expr(deref->unop);
 151
 152                         if (unop->type == EXPR_PREOP && unop->op == '&') {
 153                                 deref = unop->unop;
 154                                 op = '.';
 155                         } else {
 156                                 deref = deref->unop;
 157                                 if (!is_pointer(deref))
 158                                         op = '.';
 159                         }
 160                 }
 161
 162                 __get_variable_from_expr(sym_ptr, buf, deref, len, complicated, no_parens);
 163
 164                 if (op == '*')
 165                         append(buf, "->", len);
 166                 else
 167                         append(buf, ".", len);
 168
 169                 if (expr->member)
 170                         append(buf, expr->member->name, len);
 171                 else
 172                         append(buf, "unknown_member", len);
 173
 174                 return;
 175         }
 176         case EXPR_SYMBOL:
 177                 if (expr->symbol_name)
 178                         append(buf, expr->symbol_name->name, len);
 179                 if (sym_ptr) {
 180                         if (*sym_ptr)
 181                                 *complicated = 1;
 182                         *sym_ptr = expr->symbol;
 183                 }
 184                 return;
 185         case EXPR_PREOP: {
 186                 const char *tmp;
 187
 188                 if (get_expression_statement(expr)) {
 189                         *complicated = 2;
 190                         return;
 191                 }
 192
 193                 if (expr->op == '(') {
 194                         if (!no_parens && expr->unop->type != EXPR_SYMBOL)
 195                                 append(buf, "(", len);
 196                 } else if (expr->op != '*' || !get_array_expr(expr->unop)) {
 197                         tmp = show_special(expr->op);
 198                         append(buf, tmp, len);
 199                 }
 200                 __get_variable_from_expr(sym_ptr, buf, expr->unop,
 201                                                  len, complicated, no_parens);
 202
 203                 if (expr->op == '(' && !no_parens && expr->unop->type != EXPR_SYMBOL)
 204                         append(buf, ")", len);
 205
 206                 if (expr->op == SPECIAL_DECREMENT ||
 207                                 expr->op == SPECIAL_INCREMENT)
 208                         *complicated = 1;
 209
 210                 return;
 211         }
 212         case EXPR_POSTOP: {
 213                 const char *tmp;
 214
 215                 __get_variable_from_expr(sym_ptr, buf, expr->unop,
 216                                                  len, complicated, no_parens);
 217                 tmp = show_special(expr->op);
 218                 append(buf, tmp, len);
 219
 220                 if (expr->op == SPECIAL_DECREMENT || expr->op == SPECIAL_INCREMENT)
 221                         *complicated = 1;
 222                 return;
 223         }
 224         case EXPR_ASSIGNMENT:
 225         case EXPR_COMPARE:
 226         case EXPR_LOGICAL:
 227         case EXPR_BINOP: {
 228                 char tmp[10];
 229                 struct expression *array_expr;
 230
 231                 *complicated = 1;
 232                 array_expr = get_array_expr(expr);
 233                 if (array_expr) {
 234                         __get_variable_from_expr(sym_ptr, buf, array_expr, len, complicated, no_parens);
 235                         append(buf, "[", len);
 236                 } else {
 237                         __get_variable_from_expr(sym_ptr, buf, expr->left, len, complicated, no_parens);
 238                         snprintf(tmp, sizeof(tmp), " %s ", show_special(expr->op));
 239                         append(buf, tmp, len);
 240                 }
 241                 __get_variable_from_expr(NULL, buf, expr->right, len, complicated, no_parens);
 242                 if (array_expr)
 243                         append(buf, "]", len);
 244                 return;
 245         }
 246         case EXPR_VALUE: {
 247                 char tmp[25];
 248
 249                 *complicated = 1;
 250                 snprintf(tmp, 25, "%lld", expr->value);
 251                 append(buf, tmp, len);
 252                 return;
 253         }
 254         case EXPR_STRING:
 255                 append(buf, "\"", len);
 256                 if (expr->string)
 257                         append(buf, expr->string->data, len);
 258                 append(buf, "\"", len);
 259                 return;
 260         case EXPR_CALL: {
 261                 struct expression *tmp;
 262                 int i;
 263
 264                 *complicated = 1;
 265                 __get_variable_from_expr(NULL, buf, expr->fn, len, complicated, no_parens);
 266                 append(buf, "(", len);
 267                 i = 0;
 268                 FOR_EACH_PTR(expr->args, tmp) {
 269                         if (i++)
 270                                 append(buf, ", ", len);
 271                         __get_variable_from_expr(NULL, buf, tmp, len, complicated, no_parens);
 272                 } END_FOR_EACH_PTR(tmp);
 273                 append(buf, ")", len);
 274                 return;
 275         }
 276         case EXPR_CAST:
 277         case EXPR_FORCE_CAST:
 278                 __get_variable_from_expr(sym_ptr, buf,
 279                                          expr->cast_expression, len,
 280                                          complicated, no_parens);
 281                 return;
 282         case EXPR_SIZEOF: {
 283                 int size;
 284                 char tmp[25];
 285
 286                 if (expr->cast_type && get_base_type(expr->cast_type)) {
 287                         size = type_bytes(get_base_type(expr->cast_type));
 288                         snprintf(tmp, 25, "%d", size);
 289                         append(buf, tmp, len);
 290                 }
 291                 return;
 292         }
 293         case EXPR_IDENTIFIER:
 294                 *complicated = 1;
 295                 if (expr->expr_ident)
 296                         append(buf, expr->expr_ident->name, len);
 297                 return;
 298         default:
 299                 *complicated = 1;
 300                 //printf("unknown type = %d\n", expr->type);
 301                 return;
 302         }
 303 }
 304
 305 /*
 306  * This is returns a stylized "c looking" representation of the
 307  * variable name.
 308  *
 309  * It uses the same buffer every time so you have to save the result
 310  * yourself if you want to keep it.
 311  *
 312  */
 313
 314 char *expr_to_str_sym(struct expression *expr, struct symbol **sym_ptr)
 315 {
 316         static char var_name[VAR_LEN];
 317         int complicated = 0;
 318
 319         if (sym_ptr)
 320                 *sym_ptr = NULL;
 321         var_name[0] = '\0';
 322
 323         if (!expr)
 324                 return NULL;
 325         __get_variable_from_expr(sym_ptr, var_name, expr, sizeof(var_name),
 326                                  &complicated, 0);
 327         if (complicated < 2)
 328                 return alloc_string(var_name);
 329         else
 330                 return NULL;
 331 }
 332
 333 char *expr_to_str(struct expression *expr)
 334 {
 335         return expr_to_str_sym(expr, NULL);
 336 }
 337
 338 /*
 339  * get_variable_from_expr_simple() only returns simple variables.
 340  * If it's a complicated variable like a->foo[x] instead of just 'a->foo'
 341  * then it returns NULL.
 342  */
 343 char *expr_to_var_sym(struct expression *expr,
 344                                     struct symbol **sym_ptr)
 345 {
 346         static char var_name[VAR_LEN];
 347         int complicated = 0;
 348
 349         if (sym_ptr)
 350                 *sym_ptr = NULL;
 351         var_name[0] = '\0';
 352
 353         if (!expr)
 354                 return NULL;
 355         expr = strip_expr(expr);
 356         __get_variable_from_expr(sym_ptr, var_name, expr, sizeof(var_name),
 357                                  &complicated, 1);
 358
 359         if (complicated) {
 360                 if (sym_ptr)
 361                         *sym_ptr = NULL;
 362                 return NULL;
 363         }
 364         return alloc_string(var_name);
 365 }
 366
 367 char *expr_to_var(struct expression *expr)
 368 {
 369         return expr_to_var_sym(expr, NULL);
 370 }
 371
 372 struct symbol *expr_to_sym(struct expression *expr)
 373 {
 374         struct symbol *sym;
 375         char *name;
 376
 377         name = expr_to_var_sym(expr, &sym);
 378         free_string(name);
 379         return sym;
 380 }
 381
 382 int get_complication_score(struct expression *expr)
 383 {
 384         int score = 0;
 385
 386         expr = strip_expr(expr);
 387
 388         /*
 389          * Don't forget to keep get_complication_score() and store_all_links()
 390          * in sync.
 391          *
 392          */
 393
 394         switch (expr->type) {
 395         case EXPR_CALL:
 396                 return 999;
 397         case EXPR_COMPARE:
 398         case EXPR_BINOP:
 399                 score += get_complication_score(expr->left);
 400                 score += get_complication_score(expr->right);
 401                 return score;
 402         case EXPR_SYMBOL:
 403                 if (is_local_variable(expr))
 404                         return 1;
 405                 return 999;
 406         case EXPR_PREOP:
 407                 if (expr->op == '*')
 408                         return score + get_complication_score(expr->unop);
 409                 return 999;
 410         case EXPR_DEREF:
 411                 return score + get_complication_score(expr->deref);
 412         case EXPR_VALUE:
 413                 return 0;
 414         default:
 415                 return 999;
 416         }
 417 }
 418
 419 char *expr_to_chunk_helper(struct expression *expr, struct symbol **sym, struct var_sym_list **vsl)
 420 {
 421         char *name;
 422         struct symbol *tmp;
 423         int score;
 424
 425         if (vsl)
 426                 *vsl = NULL;
 427         if (sym)
 428                 *sym = NULL;
 429
 430         expr = strip_parens(expr);
 431         if (!expr)
 432                 return NULL;
 433
 434         name = expr_to_var_sym(expr, &tmp);
 435         if (name && tmp) {
 436                 if (sym)
 437                         *sym = tmp;
 438                 if (vsl)
 439                         *vsl = expr_to_vsl(expr);
 440                 return name;
 441         }
 442         free_string(name);
 443
 444         score = get_complication_score(expr);
 445         if (score <= 0 || score > 2)
 446                 return NULL;
 447
 448         if (vsl) {
 449                 *vsl = expr_to_vsl(expr);
 450                 if (!*vsl)
 451                         return NULL;
 452         }
 453
 454         return expr_to_str(expr);
 455 }
 456
 457 char *expr_to_known_chunk_sym(struct expression *expr, struct symbol **sym)
 458 {
 459         return expr_to_chunk_helper(expr, sym, NULL);
 460 }
 461
 462 char *expr_to_chunk_sym_vsl(struct expression *expr, struct symbol **sym, struct var_sym_list **vsl)
 463 {
 464         return expr_to_chunk_helper(expr, sym, vsl);
 465 }
 466
 467 int sym_name_is(const char *name, struct expression *expr)
 468 {
 469         if (!expr)
 470                 return 0;
 471         if (expr->type != EXPR_SYMBOL)
 472                 return 0;
 473         if (!strcmp(expr->symbol_name->name, name))
 474                 return 1;
 475         return 0;
 476 }
 477
 478 int is_zero(struct expression *expr)
 479 {
 480         sval_t sval;
 481
 482         if (get_value(expr, &sval) && sval.value == 0)
 483                 return 1;
 484         return 0;
 485 }
 486
 487 int is_array(struct expression *expr)
 488 {
 489         struct symbol *type;
 490
 491         expr = strip_expr(expr);
 492         if (!expr)
 493                 return 0;
 494
 495         if (expr->type == EXPR_PREOP && expr->op == '*') {
 496                 expr = strip_expr(expr->unop);
 497                 if (expr->type == EXPR_BINOP && expr->op == '+')
 498                         return 1;
 499         }
 500
 501         if (expr->type != EXPR_BINOP || expr->op != '+')
 502                 return 0;
 503
 504         type = get_type(expr->left);
 505         if (!type || type->type != SYM_ARRAY)
 506                 return 0;
 507
 508         return 1;
 509 }
 510
 511 struct expression *get_array_base(struct expression *expr)
 512 {
 513         if (!is_array(expr))
 514                 return NULL;
 515         expr = strip_expr(expr);
 516         if (expr->type == EXPR_PREOP && expr->op == '*')
 517                 expr = strip_expr(expr->unop);
 518         if (expr->type != EXPR_BINOP || expr->op != '+')
 519                 return NULL;
 520         return strip_parens(expr->left);
 521 }
 522
 523 struct expression *get_array_offset(struct expression *expr)
 524 {
 525         if (!is_array(expr))
 526                 return NULL;
 527         expr = strip_expr(expr);
 528         if (expr->type == EXPR_PREOP && expr->op == '*')
 529                 expr = strip_expr(expr->unop);
 530         if (expr->type != EXPR_BINOP || expr->op != '+')
 531                 return NULL;
 532         return strip_parens(expr->right);
 533 }
 534
 535 const char *show_state(struct smatch_state *state)
 536 {
 537         if (!state)
 538                 return NULL;
 539         return state->name;
 540 }
 541
 542 struct statement *get_expression_statement(struct expression *expr)
 543 {
 544         /* What are those things called? if (({....; ret;})) { ...*/
 545
 546         if (expr->type != EXPR_PREOP)
 547                 return NULL;
 548         if (expr->op != '(')
 549                 return NULL;
 550         if (expr->unop->type != EXPR_STATEMENT)
 551                 return NULL;
 552         if (expr->unop->statement->type != STMT_COMPOUND)
 553                 return NULL;
 554         return expr->unop->statement;
 555 }
 556
 557 struct expression *strip_parens(struct expression *expr)
 558 {
 559         if (!expr)
 560                 return NULL;
 561
 562         if (expr->type == EXPR_PREOP) {
 563                 if (expr->op == '(' && expr->unop->type == EXPR_STATEMENT &&
 564                         expr->unop->statement->type == STMT_COMPOUND)
 565                         return expr;
 566                 if (expr->op == '(')
 567                         return strip_parens(expr->unop);
 568         }
 569         return expr;
 570 }
 571
 572 struct expression *strip_expr(struct expression *expr)
 573 {
 574         if (!expr)
 575                 return NULL;
 576
 577         switch (expr->type) {
 578         case EXPR_FORCE_CAST:
 579         case EXPR_CAST:
 580                 return strip_expr(expr->cast_expression);
 581         case EXPR_PREOP: {
 582                 struct expression *unop;
 583
 584                 if (expr->op == '(' && expr->unop->type == EXPR_STATEMENT &&
 585                         expr->unop->statement->type == STMT_COMPOUND)
 586                         return expr;
 587
 588                 unop = strip_expr(expr->unop);
 589
 590                 if (expr->op == '*' &&
 591                     unop->type == EXPR_PREOP && unop->op == '&') {
 592                         struct symbol *type = get_type(unop->unop);
 593
 594                         if (type && type->type == SYM_ARRAY)
 595                                 return expr;
 596                         return strip_expr(unop->unop);
 597                 }
 598
 599                 if (expr->op == '(')
 600                         return unop;
 601
 602                 return expr;
 603         }
 604         case EXPR_CONDITIONAL:
 605                 if (known_condition_true(expr->conditional)) {
 606                         if (expr->cond_true)
 607                                 return strip_expr(expr->cond_true);
 608                         return strip_expr(expr->conditional);
 609                 }
 610                 if (known_condition_false(expr->conditional))
 611                         return strip_expr(expr->cond_false);
 612                 return expr;
 613         case EXPR_CALL:
 614                 if (sym_name_is("__builtin_expect", expr->fn)) {
 615                         expr = get_argument_from_call_expr(expr->args, 0);
 616                         return strip_expr(expr);
 617                 }
 618                 return expr;
 619         }
 620         return expr;
 621 }
 622
 623 static void delete_state_tracker(struct tracker *t)
 624 {
 625         delete_state(t->owner, t->name, t->sym);
 626         __free_tracker(t);
 627 }
 628
 629 void scoped_state(int my_id, const char *name, struct symbol *sym)
 630 {
 631         struct tracker *t;
 632
 633         t = alloc_tracker(my_id, name, sym);
 634         add_scope_hook((scope_hook *)&delete_state_tracker, t);
 635 }
 636
 637 int is_error_return(struct expression *expr)
 638 {
 639         struct symbol *cur_func = cur_func_sym;
 640         sval_t sval;
 641
 642         if (!expr)
 643                 return 0;
 644         if (cur_func->type != SYM_NODE)
 645                 return 0;
 646         cur_func = get_base_type(cur_func);
 647         if (cur_func->type != SYM_FN)
 648                 return 0;
 649         cur_func = get_base_type(cur_func);
 650         if (cur_func == &void_ctype)
 651                 return 0;
 652         if (!get_implied_value(expr, &sval))
 653                 return 0;
 654         if (sval.value < 0)
 655                 return 1;
 656         if (cur_func->type == SYM_PTR && sval.value == 0)
 657                 return 1;
 658         return 0;
 659 }
 660
 661 int getting_address(void)
 662 {
 663         struct expression *tmp;
 664         int i = 0;
 665         int dot_ops = 0;
 666
 667         FOR_EACH_PTR_REVERSE(big_expression_stack, tmp) {
 668                 if (!i++)
 669                         continue;
 670                 if (tmp->type == EXPR_PREOP && tmp->op == '(')
 671                         continue;
 672                 if (tmp->op == '.' && !dot_ops++)
 673                         continue;
 674                 if (tmp->op == '&')
 675                         return 1;
 676                 return 0;
 677         } END_FOR_EACH_PTR_REVERSE(tmp);
 678         return 0;
 679 }
 680
 681 int get_struct_and_member(struct expression *expr, const char **type, const char **member)
 682 {
 683         struct symbol *sym;
 684
 685         expr = strip_expr(expr);
 686         if (expr->type != EXPR_DEREF)
 687                 return 0;
 688         if (!expr->member)
 689                 return 0;
 690
 691         sym = get_type(expr->deref);
 692         if (!sym)
 693                 return 0;
 694         if (sym->type == SYM_UNION)
 695                 return 0;
 696         if (!sym->ident)
 697                 return 0;
 698
 699         *type = sym->ident->name;
 700         *member = expr->member->name;
 701         return 1;
 702 }
 703
 704 char *get_member_name(struct expression *expr)
 705 {
 706         char buf[256];
 707         struct symbol *sym;
 708
 709         expr = strip_expr(expr);
 710         if (expr->type != EXPR_DEREF)
 711                 return NULL;
 712         if (!expr->member)
 713                 return NULL;
 714
 715         sym = get_type(expr->deref);
 716         if (!sym)
 717                 return NULL;
 718         if (sym->type == SYM_UNION) {
 719                 sym = expr_to_sym(expr->deref);
 720                 sym = get_real_base_type(sym);
 721                 if (sym && sym->type == SYM_PTR)
 722                         sym = get_real_base_type(sym);
 723                 if (!sym || !sym->ident) {
 724                         snprintf(buf, sizeof(buf), "(union hack)->%s", expr->member->name);
 725                         return alloc_string(buf);
 726                 }
 727         }
 728         if (!sym->ident)
 729                 return NULL;
 730         snprintf(buf, sizeof(buf), "(struct %s)->%s", sym->ident->name, expr->member->name);
 731         return alloc_string(buf);
 732 }
 733
 734 int cmp_pos(struct position pos1, struct position pos2)
 735 {
 736         /* the stream position is ... */
 737         if (pos1.stream > pos2.stream)
 738                 return -1;
 739         if (pos1.stream < pos2.stream)
 740                 return 1;
 741
 742         if (pos1.line < pos2.line)
 743                 return -1;
 744         if (pos1.line > pos2.line)
 745                 return 1;
 746
 747         if (pos1.pos < pos2.pos)
 748                 return -1;
 749         if (pos1.pos > pos2.pos)
 750                 return 1;
 751
 752         return 0;
 753 }
 754
 755 int positions_eq(struct position pos1, struct position pos2)
 756 {
 757         if (pos1.line != pos2.line)
 758                 return 0;
 759         if (pos1.pos != pos2.pos)
 760                 return 0;
 761         if (pos1.stream != pos2.stream)
 762                 return 0;
 763         return 1;
 764 }
 765
 766 struct statement *get_current_statement(void)
 767 {
 768         struct statement *prev, *tmp;
 769
 770         prev = last_ptr_list((struct ptr_list *)big_statement_stack);
 771
 772         if (!prev || !get_macro_name(prev->pos))
 773                 return prev;
 774
 775         FOR_EACH_PTR_REVERSE(big_statement_stack, tmp) {
 776                 if (positions_eq(tmp->pos, prev->pos))
 777                         continue;
 778                 if (prev->pos.line > tmp->pos.line)
 779                         return prev;
 780                 return tmp;
 781         } END_FOR_EACH_PTR_REVERSE(tmp);
 782         return prev;
 783 }
 784
 785 struct statement *get_prev_statement(void)
 786 {
 787         struct statement *tmp;
 788         int i;
 789
 790         i = 0;
 791         FOR_EACH_PTR_REVERSE(big_statement_stack, tmp) {
 792                 if (i++ == 1)
 793                         return tmp;
 794         } END_FOR_EACH_PTR_REVERSE(tmp);
 795         return NULL;
 796 }
 797
 798 int get_param_num_from_sym(struct symbol *sym)
 799 {
 800         struct symbol *tmp;
 801         int i;
 802
 803         if (!cur_func_sym)
 804                 return -1;
 805
 806         i = 0;
 807         FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, tmp) {
 808                 if (tmp == sym)
 809                         return i;
 810                 i++;
 811         } END_FOR_EACH_PTR(tmp);
 812         return -1;
 813 }
 814
 815 int get_param_num(struct expression *expr)
 816 {
 817         struct symbol *sym;
 818         char *name;
 819
 820         if (!cur_func_sym)
 821                 return -1;
 822         name = expr_to_var_sym(expr, &sym);
 823         free_string(name);
 824         if (!sym)
 825                 return -1;
 826         return get_param_num_from_sym(sym);
 827 }
 828
 829 int ms_since(struct timeval *start)
 830 {
 831         struct timeval end;
 832         double diff;
 833
 834         gettimeofday(&end, NULL);
 835         diff = (end.tv_sec - start->tv_sec) * 1000.0;
 836         diff += (end.tv_usec - start->tv_usec) / 1000.0;
 837         return (int)diff;
 838 }
 839
 840 int parent_is_gone_var_sym(const char *name, struct symbol *sym)
 841 {
 842         if (!name || !sym)
 843                 return 0;
 844
 845         if (parent_is_null_var_sym(name, sym) ||
 846             parent_is_free_var_sym(name, sym))
 847                 return 1;
 848         return 0;
 849 }
 850
 851 int parent_is_gone(struct expression *expr)
 852 {
 853         struct symbol *sym;
 854         char *var;
 855         int ret = 0;
 856
 857         expr = strip_expr(expr);
 858         var = expr_to_var_sym(expr, &sym);
 859         if (!var || !sym)
 860                 goto free;
 861         ret = parent_is_gone_var_sym(var, sym);
 862 free:
 863         free_string(var);
 864         return ret;
 865 }
 866
 867 int invert_op(int op)
 868 {
 869         switch (op) {
 870         case '*':
 871                 return '/';
 872         case '/':
 873                 return '*';
 874         case '+':
 875                 return '-';
 876         case '-':
 877                 return '+';
 878         case SPECIAL_LEFTSHIFT:
 879                 return SPECIAL_RIGHTSHIFT;
 880         case SPECIAL_RIGHTSHIFT:
 881                 return SPECIAL_LEFTSHIFT;
 882         }
 883         return 0;
 884 }
 885
 886 int expr_equiv(struct expression *one, struct expression *two)
 887 {
 888         struct symbol *one_sym, *two_sym;
 889         char *one_name = NULL;
 890         char *two_name = NULL;
 891         int ret = 0;
 892
 893         if (!one || !two)
 894                 return 0;
 895         if (one->type != two->type)
 896                 return 0;
 897
 898         one_name = expr_to_str_sym(one, &one_sym);
 899         if (!one_name || !one_sym)
 900                 goto free;
 901         two_name = expr_to_str_sym(two, &two_sym);
 902         if (!two_name || !two_sym)
 903                 goto free;
 904         if (one_sym != two_sym)
 905                 goto free;
 906         if (strcmp(one_name, two_name) == 0)
 907                 ret = 1;
 908 free:
 909         free_string(one_name);
 910         free_string(two_name);
 911         return ret;
 912 }
 913
 914 void push_int(struct int_stack **stack, int num)
 915 {
 916         int *munged;
 917
 918         /*
 919          * Just put the int on directly instead of a pointer to the int.
 920          * Shift it to the left because Sparse uses the last two bits.
 921          * This is sort of a dirty hack, yes.
 922          */
 923
 924         munged = INT_PTR(num << 2);
 925
 926         add_ptr_list(stack, munged);
 927 }
 928
 929 int pop_int(struct int_stack **stack)
 930 {
 931         int *num;
 932
 933         num = last_ptr_list((struct ptr_list *)*stack);
 934         delete_ptr_list_last((struct ptr_list **)stack);
 935
 936         return PTR_INT(num) >> 2;
 937 }