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
 143
 144         if (!expr) {
 145                 /* can't happen on valid code */
 146                 *complicated = 1;
 147                 return;
 148         }
 149
 150         switch (expr->type) {
 151         case EXPR_DEREF: {
 152                 struct expression *deref;
 153                 int op;
 154
 155                 deref = expr->deref;
 156                 op = deref->op;
 157                 if (op == '*') {
 158                         struct expression *unop = strip_expr(deref->unop);
 159
 160                         if (unop->type == EXPR_PREOP && unop->op == '&') {
 161                                 deref = unop->unop;
 162                                 op = '.';
 163                         } else {
 164                                 deref = deref->unop;
 165                                 if (!is_pointer(deref))
 166                                         op = '.';
 167                         }
 168                 }
 169
 170                 __get_variable_from_expr(sym_ptr, buf, deref, len, complicated, no_parens);
 171
 172                 if (op == '*')
 173                         append(buf, "->", len);
 174                 else
 175                         append(buf, ".", len);
 176
 177                 if (expr->member)
 178                         append(buf, expr->member->name, len);
 179                 else
 180                         append(buf, "unknown_member", len);
 181
 182                 return;
 183         }
 184         case EXPR_SYMBOL:
 185                 if (expr->symbol_name)
 186                         append(buf, expr->symbol_name->name, len);
 187                 if (sym_ptr) {
 188                         if (*sym_ptr)
 189                                 *complicated = 1;
 190                         *sym_ptr = expr->symbol;
 191                 }
 192                 return;
 193         case EXPR_PREOP: {
 194                 const char *tmp;
 195
 196                 if (get_expression_statement(expr)) {
 197                         *complicated = 2;
 198                         return;
 199                 }
 200
 201                 if (expr->op == '(') {
 202                         if (!no_parens && expr->unop->type != EXPR_SYMBOL)
 203                                 append(buf, "(", len);
 204                 } else if (expr->op != '*' || !get_array_expr(expr->unop)) {
 205                         tmp = show_special(expr->op);
 206                         append(buf, tmp, len);
 207                 }
 208                 __get_variable_from_expr(sym_ptr, buf, expr->unop,
 209                                                  len, complicated, no_parens);
 210
 211                 if (expr->op == '(' && !no_parens && expr->unop->type != EXPR_SYMBOL)
 212                         append(buf, ")", len);
 213
 214                 if (expr->op == SPECIAL_DECREMENT ||
 215                                 expr->op == SPECIAL_INCREMENT)
 216                         *complicated = 1;
 217
 218                 return;
 219         }
 220         case EXPR_POSTOP: {
 221                 const char *tmp;
 222
 223                 __get_variable_from_expr(sym_ptr, buf, expr->unop,
 224                                                  len, complicated, no_parens);
 225                 tmp = show_special(expr->op);
 226                 append(buf, tmp, len);
 227
 228                 if (expr->op == SPECIAL_DECREMENT || expr->op == SPECIAL_INCREMENT)
 229                         *complicated = 1;
 230                 return;
 231         }
 232         case EXPR_ASSIGNMENT:
 233         case EXPR_COMPARE:
 234         case EXPR_LOGICAL:
 235         case EXPR_BINOP: {
 236                 char tmp[10];
 237                 struct expression *array_expr;
 238
 239                 *complicated = 1;
 240                 array_expr = get_array_expr(expr);
 241                 if (array_expr) {
 242                         __get_variable_from_expr(sym_ptr, buf, array_expr, len, complicated, no_parens);
 243                         append(buf, "[", len);
 244                 } else {
 245                         __get_variable_from_expr(sym_ptr, buf, expr->left, len, complicated, no_parens);
 246                         snprintf(tmp, sizeof(tmp), " %s ", show_special(expr->op));
 247                         append(buf, tmp, len);
 248                 }
 249                 __get_variable_from_expr(NULL, buf, expr->right, len, complicated, no_parens);
 250                 if (array_expr)
 251                         append(buf, "]", len);
 252                 return;
 253         }
 254         case EXPR_VALUE: {
 255                 char tmp[25];
 256
 257                 *complicated = 1;
 258                 snprintf(tmp, 25, "%lld", expr->value);
 259                 append(buf, tmp, len);
 260                 return;
 261         }
 262         case EXPR_STRING:
 263                 append(buf, "\"", len);
 264                 if (expr->string)
 265                         append(buf, expr->string->data, len);
 266                 append(buf, "\"", len);
 267                 return;
 268         case EXPR_CALL: {
 269                 struct expression *tmp;
 270                 int i;
 271
 272                 *complicated = 1;
 273                 __get_variable_from_expr(NULL, buf, expr->fn, len, complicated, no_parens);
 274                 append(buf, "(", len);
 275                 i = 0;
 276                 FOR_EACH_PTR(expr->args, tmp) {
 277                         if (i++)
 278                                 append(buf, ", ", len);
 279                         __get_variable_from_expr(NULL, buf, tmp, len, complicated, no_parens);
 280                 } END_FOR_EACH_PTR(tmp);
 281                 append(buf, ")", len);
 282                 return;
 283         }
 284         case EXPR_CAST:
 285         case EXPR_FORCE_CAST:
 286                 __get_variable_from_expr(sym_ptr, buf,
 287                                          expr->cast_expression, len,
 288                                          complicated, no_parens);
 289                 return;
 290         case EXPR_SIZEOF: {
 291                 int size;
 292                 char tmp[25];
 293
 294                 if (expr->cast_type && get_base_type(expr->cast_type)) {
 295                         size = type_bytes(get_base_type(expr->cast_type));
 296                         snprintf(tmp, 25, "%d", size);
 297                         append(buf, tmp, len);
 298                 }
 299                 return;
 300         }
 301         case EXPR_IDENTIFIER:
 302                 *complicated = 1;
 303                 if (expr->expr_ident)
 304                         append(buf, expr->expr_ident->name, len);
 305                 return;
 306         default:
 307                 *complicated = 1;
 308                 //printf("unknown type = %d\n", expr->type);
 309                 return;
 310         }
 311 }
 312
 313 /*
 314  * This is returns a stylized "c looking" representation of the
 315  * variable name.
 316  *
 317  * It uses the same buffer every time so you have to save the result
 318  * yourself if you want to keep it.
 319  *
 320  */
 321
 322 char *expr_to_str_sym(struct expression *expr, struct symbol **sym_ptr)
 323 {
 324         static char var_name[VAR_LEN];
 325         int complicated = 0;
 326
 327         if (sym_ptr)
 328                 *sym_ptr = NULL;
 329         var_name[0] = '\0';
 330
 331         if (!expr)
 332                 return NULL;
 333         __get_variable_from_expr(sym_ptr, var_name, expr, sizeof(var_name),
 334                                  &complicated, 0);
 335         if (complicated < 2)
 336                 return alloc_string(var_name);
 337         else
 338                 return NULL;
 339 }
 340
 341 char *expr_to_str(struct expression *expr)
 342 {
 343         return expr_to_str_sym(expr, NULL);
 344 }
 345
 346 /*
 347  * get_variable_from_expr_simple() only returns simple variables.
 348  * If it's a complicated variable like a->foo[x] instead of just 'a->foo'
 349  * then it returns NULL.
 350  */
 351 char *expr_to_var_sym(struct expression *expr,
 352                                     struct symbol **sym_ptr)
 353 {
 354         static char var_name[VAR_LEN];
 355         int complicated = 0;
 356
 357         if (sym_ptr)
 358                 *sym_ptr = NULL;
 359         var_name[0] = '\0';
 360
 361         if (!expr)
 362                 return NULL;
 363         expr = strip_expr(expr);
 364         __get_variable_from_expr(sym_ptr, var_name, expr, sizeof(var_name),
 365                                  &complicated, 1);
 366
 367         if (complicated) {
 368                 if (sym_ptr)
 369                         *sym_ptr = NULL;
 370                 return NULL;
 371         }
 372         return alloc_string(var_name);
 373 }
 374
 375 char *expr_to_var(struct expression *expr)
 376 {
 377         return expr_to_var_sym(expr, NULL);
 378 }
 379
 380 struct symbol *expr_to_sym(struct expression *expr)
 381 {
 382         struct symbol *sym;
 383         char *name;
 384
 385         name = expr_to_var_sym(expr, &sym);
 386         free_string(name);
 387         return sym;
 388 }
 389
 390 int get_complication_score(struct expression *expr)
 391 {
 392         int score = 0;
 393
 394         expr = strip_expr(expr);
 395
 396         /*
 397          * Don't forget to keep get_complication_score() and store_all_links()
 398          * in sync.
 399          *
 400          */
 401
 402         if (!expr)
 403                 return 999;
 404
 405         switch (expr->type) {
 406         case EXPR_CALL:
 407                 return 999;
 408         case EXPR_COMPARE:
 409         case EXPR_BINOP:
 410                 score += get_complication_score(expr->left);
 411                 score += get_complication_score(expr->right);
 412                 return score;
 413         case EXPR_SYMBOL:
 414                 if (is_local_variable(expr))
 415                         return 1;
 416                 return 999;
 417         case EXPR_PREOP:
 418                 if (expr->op == '*')
 419                         return score + get_complication_score(expr->unop);
 420                 return 999;
 421         case EXPR_DEREF:
 422                 return score + get_complication_score(expr->deref);
 423         case EXPR_VALUE:
 424                 return 0;
 425         default:
 426                 return 999;
 427         }
 428 }
 429
 430 char *expr_to_chunk_helper(struct expression *expr, struct symbol **sym, struct var_sym_list **vsl)
 431 {
 432         char *name;
 433         struct symbol *tmp;
 434         int score;
 435
 436         if (vsl)
 437                 *vsl = NULL;
 438         if (sym)
 439                 *sym = NULL;
 440
 441         expr = strip_parens(expr);
 442         if (!expr)
 443                 return NULL;
 444
 445         name = expr_to_var_sym(expr, &tmp);
 446         if (name && tmp) {
 447                 if (sym)
 448                         *sym = tmp;
 449                 if (vsl)
 450                         *vsl = expr_to_vsl(expr);
 451                 return name;
 452         }
 453         free_string(name);
 454
 455         score = get_complication_score(expr);
 456         if (score <= 0 || score > 2)
 457                 return NULL;
 458
 459         if (vsl) {
 460                 *vsl = expr_to_vsl(expr);
 461                 if (!*vsl)
 462                         return NULL;
 463         }
 464
 465         return expr_to_str(expr);
 466 }
 467
 468 char *expr_to_known_chunk_sym(struct expression *expr, struct symbol **sym)
 469 {
 470         return expr_to_chunk_helper(expr, sym, NULL);
 471 }
 472
 473 char *expr_to_chunk_sym_vsl(struct expression *expr, struct symbol **sym, struct var_sym_list **vsl)
 474 {
 475         return expr_to_chunk_helper(expr, sym, vsl);
 476 }
 477
 478 int sym_name_is(const char *name, struct expression *expr)
 479 {
 480         if (!expr)
 481                 return 0;
 482         if (expr->type != EXPR_SYMBOL)
 483                 return 0;
 484         if (!strcmp(expr->symbol_name->name, name))
 485                 return 1;
 486         return 0;
 487 }
 488
 489 int is_zero(struct expression *expr)
 490 {
 491         sval_t sval;
 492
 493         if (get_value(expr, &sval) && sval.value == 0)
 494                 return 1;
 495         return 0;
 496 }
 497
 498 int is_array(struct expression *expr)
 499 {
 500         struct symbol *type;
 501
 502         expr = strip_expr(expr);
 503         if (!expr)
 504                 return 0;
 505
 506         if (expr->type == EXPR_PREOP && expr->op == '*') {
 507                 expr = strip_expr(expr->unop);
 508                 if (!expr)
 509                         return 0;
 510                 if (expr->type == EXPR_BINOP && expr->op == '+')
 511                         return 1;
 512         }
 513
 514         if (expr->type != EXPR_BINOP || expr->op != '+')
 515                 return 0;
 516
 517         type = get_type(expr->left);
 518         if (!type || type->type != SYM_ARRAY)
 519                 return 0;
 520
 521         return 1;
 522 }
 523
 524 struct expression *get_array_base(struct expression *expr)
 525 {
 526         if (!is_array(expr))
 527                 return NULL;
 528         expr = strip_expr(expr);
 529         if (expr->type == EXPR_PREOP && expr->op == '*')
 530                 expr = strip_expr(expr->unop);
 531         if (expr->type != EXPR_BINOP || expr->op != '+')
 532                 return NULL;
 533         return strip_parens(expr->left);
 534 }
 535
 536 struct expression *get_array_offset(struct expression *expr)
 537 {
 538         if (!is_array(expr))
 539                 return NULL;
 540         expr = strip_expr(expr);
 541         if (expr->type == EXPR_PREOP && expr->op == '*')
 542                 expr = strip_expr(expr->unop);
 543         if (expr->type != EXPR_BINOP || expr->op != '+')
 544                 return NULL;
 545         return strip_parens(expr->right);
 546 }
 547
 548 const char *show_state(struct smatch_state *state)
 549 {
 550         if (!state)
 551                 return NULL;
 552         return state->name;
 553 }
 554
 555 struct statement *get_expression_statement(struct expression *expr)
 556 {
 557         /* What are those things called? if (({....; ret;})) { ...*/
 558
 559         if (expr->type != EXPR_PREOP)
 560                 return NULL;
 561         if (expr->op != '(')
 562                 return NULL;
 563         if (expr->unop->type != EXPR_STATEMENT)
 564                 return NULL;
 565         if (expr->unop->statement->type != STMT_COMPOUND)
 566                 return NULL;
 567         return expr->unop->statement;
 568 }
 569
 570 struct expression *strip_parens(struct expression *expr)
 571 {
 572         if (!expr)
 573                 return NULL;
 574
 575         if (expr->type == EXPR_PREOP) {
 576                 if (expr->op == '(' && expr->unop->type == EXPR_STATEMENT &&
 577                         expr->unop->statement->type == STMT_COMPOUND)
 578                         return expr;
 579                 if (expr->op == '(')
 580                         return strip_parens(expr->unop);
 581         }
 582         return expr;
 583 }
 584
 585 struct expression *strip_expr(struct expression *expr)
 586 {
 587         if (!expr)
 588                 return NULL;
 589
 590         switch (expr->type) {
 591         case EXPR_FORCE_CAST:
 592         case EXPR_CAST:
 593                 return strip_expr(expr->cast_expression);
 594         case EXPR_PREOP: {
 595                 struct expression *unop;
 596
 597                 if (expr->op == '(' && expr->unop->type == EXPR_STATEMENT &&
 598                         expr->unop->statement->type == STMT_COMPOUND)
 599                         return expr;
 600
 601                 unop = strip_expr(expr->unop);
 602
 603                 if (expr->op == '*' && unop &&
 604                     unop->type == EXPR_PREOP && unop->op == '&') {
 605                         struct symbol *type = get_type(unop->unop);
 606
 607                         if (type && type->type == SYM_ARRAY)
 608                                 return expr;
 609                         return strip_expr(unop->unop);
 610                 }
 611
 612                 if (expr->op == '(')
 613                         return unop;
 614
 615                 return expr;
 616         }
 617         case EXPR_CONDITIONAL:
 618                 if (known_condition_true(expr->conditional)) {
 619                         if (expr->cond_true)
 620                                 return strip_expr(expr->cond_true);
 621                         return strip_expr(expr->conditional);
 622                 }
 623                 if (known_condition_false(expr->conditional))
 624                         return strip_expr(expr->cond_false);
 625                 return expr;
 626         case EXPR_CALL:
 627                 if (sym_name_is("__builtin_expect", expr->fn)) {
 628                         expr = get_argument_from_call_expr(expr->args, 0);
 629                         return strip_expr(expr);
 630                 }
 631                 return expr;
 632         }
 633         return expr;
 634 }
 635
 636 static void delete_state_tracker(struct tracker *t)
 637 {
 638         delete_state(t->owner, t->name, t->sym);
 639         __free_tracker(t);
 640 }
 641
 642 void scoped_state(int my_id, const char *name, struct symbol *sym)
 643 {
 644         struct tracker *t;
 645
 646         t = alloc_tracker(my_id, name, sym);
 647         add_scope_hook((scope_hook *)&delete_state_tracker, t);
 648 }
 649
 650 int is_error_return(struct expression *expr)
 651 {
 652         struct symbol *cur_func = cur_func_sym;
 653         sval_t sval;
 654
 655         if (!expr)
 656                 return 0;
 657         if (cur_func->type != SYM_NODE)
 658                 return 0;
 659         cur_func = get_base_type(cur_func);
 660         if (cur_func->type != SYM_FN)
 661                 return 0;
 662         cur_func = get_base_type(cur_func);
 663         if (cur_func == &void_ctype)
 664                 return 0;
 665         if (!get_implied_value(expr, &sval))
 666                 return 0;
 667         if (sval.value < 0)
 668                 return 1;
 669         if (cur_func->type == SYM_PTR && sval.value == 0)
 670                 return 1;
 671         return 0;
 672 }
 673
 674 int getting_address(void)
 675 {
 676         struct expression *tmp;
 677         int i = 0;
 678         int dot_ops = 0;
 679
 680         FOR_EACH_PTR_REVERSE(big_expression_stack, tmp) {
 681                 if (!i++)
 682                         continue;
 683                 if (tmp->type == EXPR_PREOP && tmp->op == '(')
 684                         continue;
 685                 if (tmp->op == '.' && !dot_ops++)
 686                         continue;
 687                 if (tmp->op == '&')
 688                         return 1;
 689                 return 0;
 690         } END_FOR_EACH_PTR_REVERSE(tmp);
 691         return 0;
 692 }
 693
 694 int get_struct_and_member(struct expression *expr, const char **type, const char **member)
 695 {
 696         struct symbol *sym;
 697
 698         expr = strip_expr(expr);
 699         if (expr->type != EXPR_DEREF)
 700                 return 0;
 701         if (!expr->member)
 702                 return 0;
 703
 704         sym = get_type(expr->deref);
 705         if (!sym)
 706                 return 0;
 707         if (sym->type == SYM_UNION)
 708                 return 0;
 709         if (!sym->ident)
 710                 return 0;
 711
 712         *type = sym->ident->name;
 713         *member = expr->member->name;
 714         return 1;
 715 }
 716
 717 char *get_member_name(struct expression *expr)
 718 {
 719         char buf[256];
 720         struct symbol *sym;
 721
 722         expr = strip_expr(expr);
 723         if (expr->type != EXPR_DEREF)
 724                 return NULL;
 725         if (!expr->member)
 726                 return NULL;
 727
 728         sym = get_type(expr->deref);
 729         if (!sym)
 730                 return NULL;
 731         if (sym->type == SYM_UNION) {
 732                 snprintf(buf, sizeof(buf), "(union %s)->%s",
 733                          sym->ident ? sym->ident->name : "anonymous",
 734                          expr->member->name);
 735                 return alloc_string(buf);
 736         }
 737         if (!sym->ident)
 738                 return NULL;
 739         snprintf(buf, sizeof(buf), "(struct %s)->%s", sym->ident->name, expr->member->name);
 740         return alloc_string(buf);
 741 }
 742
 743 int cmp_pos(struct position pos1, struct position pos2)
 744 {
 745         /* the stream position is ... */
 746         if (pos1.stream > pos2.stream)
 747                 return -1;
 748         if (pos1.stream < pos2.stream)
 749                 return 1;
 750
 751         if (pos1.line < pos2.line)
 752                 return -1;
 753         if (pos1.line > pos2.line)
 754                 return 1;
 755
 756         if (pos1.pos < pos2.pos)
 757                 return -1;
 758         if (pos1.pos > pos2.pos)
 759                 return 1;
 760
 761         return 0;
 762 }
 763
 764 int positions_eq(struct position pos1, struct position pos2)
 765 {
 766         if (pos1.line != pos2.line)
 767                 return 0;
 768         if (pos1.pos != pos2.pos)
 769                 return 0;
 770         if (pos1.stream != pos2.stream)
 771                 return 0;
 772         return 1;
 773 }
 774
 775 struct statement *get_current_statement(void)
 776 {
 777         struct statement *prev, *tmp;
 778
 779         prev = last_ptr_list((struct ptr_list *)big_statement_stack);
 780
 781         if (!prev || !get_macro_name(prev->pos))
 782                 return prev;
 783
 784         FOR_EACH_PTR_REVERSE(big_statement_stack, tmp) {
 785                 if (positions_eq(tmp->pos, prev->pos))
 786                         continue;
 787                 if (prev->pos.line > tmp->pos.line)
 788                         return prev;
 789                 return tmp;
 790         } END_FOR_EACH_PTR_REVERSE(tmp);
 791         return prev;
 792 }
 793
 794 struct statement *get_prev_statement(void)
 795 {
 796         struct statement *tmp;
 797         int i;
 798
 799         i = 0;
 800         FOR_EACH_PTR_REVERSE(big_statement_stack, tmp) {
 801                 if (i++ == 1)
 802                         return tmp;
 803         } END_FOR_EACH_PTR_REVERSE(tmp);
 804         return NULL;
 805 }
 806
 807 int get_param_num_from_sym(struct symbol *sym)
 808 {
 809         struct symbol *tmp;
 810         int i;
 811
 812         if (!cur_func_sym)
 813                 return -1;
 814
 815         i = 0;
 816         FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, tmp) {
 817                 if (tmp == sym)
 818                         return i;
 819                 i++;
 820         } END_FOR_EACH_PTR(tmp);
 821         return -1;
 822 }
 823
 824 int get_param_num(struct expression *expr)
 825 {
 826         struct symbol *sym;
 827         char *name;
 828
 829         if (!cur_func_sym)
 830                 return -1;
 831         name = expr_to_var_sym(expr, &sym);
 832         free_string(name);
 833         if (!sym)
 834                 return -1;
 835         return get_param_num_from_sym(sym);
 836 }
 837
 838 int ms_since(struct timeval *start)
 839 {
 840         struct timeval end;
 841         double diff;
 842
 843         gettimeofday(&end, NULL);
 844         diff = (end.tv_sec - start->tv_sec) * 1000.0;
 845         diff += (end.tv_usec - start->tv_usec) / 1000.0;
 846         return (int)diff;
 847 }
 848
 849 int parent_is_gone_var_sym(const char *name, struct symbol *sym)
 850 {
 851         if (!name || !sym)
 852                 return 0;
 853
 854         if (parent_is_null_var_sym(name, sym) ||
 855             parent_is_free_var_sym(name, sym))
 856                 return 1;
 857         return 0;
 858 }
 859
 860 int parent_is_gone(struct expression *expr)
 861 {
 862         struct symbol *sym;
 863         char *var;
 864         int ret = 0;
 865
 866         expr = strip_expr(expr);
 867         var = expr_to_var_sym(expr, &sym);
 868         if (!var || !sym)
 869                 goto free;
 870         ret = parent_is_gone_var_sym(var, sym);
 871 free:
 872         free_string(var);
 873         return ret;
 874 }
 875
 876 int invert_op(int op)
 877 {
 878         switch (op) {
 879         case '*':
 880                 return '/';
 881         case '/':
 882                 return '*';
 883         case '+':
 884                 return '-';
 885         case '-':
 886                 return '+';
 887         case SPECIAL_LEFTSHIFT:
 888                 return SPECIAL_RIGHTSHIFT;
 889         case SPECIAL_RIGHTSHIFT:
 890                 return SPECIAL_LEFTSHIFT;
 891         }
 892         return 0;
 893 }
 894
 895 int expr_equiv(struct expression *one, struct expression *two)
 896 {
 897         struct symbol *one_sym, *two_sym;
 898         char *one_name = NULL;
 899         char *two_name = NULL;
 900         int ret = 0;
 901
 902         if (!one || !two)
 903                 return 0;
 904         if (one->type != two->type)
 905                 return 0;
 906
 907         one_name = expr_to_str_sym(one, &one_sym);
 908         if (!one_name || !one_sym)
 909                 goto free;
 910         two_name = expr_to_str_sym(two, &two_sym);
 911         if (!two_name || !two_sym)
 912                 goto free;
 913         if (one_sym != two_sym)
 914                 goto free;
 915         if (strcmp(one_name, two_name) == 0)
 916                 ret = 1;
 917 free:
 918         free_string(one_name);
 919         free_string(two_name);
 920         return ret;
 921 }
 922
 923 void push_int(struct int_stack **stack, int num)
 924 {
 925         int *munged;
 926
 927         /*
 928          * Just put the int on directly instead of a pointer to the int.
 929          * Shift it to the left because Sparse uses the last two bits.
 930          * This is sort of a dirty hack, yes.
 931          */
 932
 933         munged = INT_PTR(num << 2);
 934
 935         add_ptr_list(stack, munged);
 936 }
 937
 938 int pop_int(struct int_stack **stack)
 939 {
 940         int *num;
 941
 942         num = last_ptr_list((struct ptr_list *)*stack);
 943         delete_ptr_list_last((struct ptr_list **)stack);
 944
 945         return PTR_INT(num) >> 2;
 946 }