smatch_extra.c

   1 /*
   2  * sparse/smatch_extra.c
   3  *
   4  * Copyright (C) 2008 Dan Carpenter.
   5  *
   6  * Licensed under the Open Software License version 1.1
   7  *
   8  */
   9
  10 /*
  11  * smatch_extra.c is supposed to track the value of every variable.
  12  */
  13
  14 #include <stdlib.h>
  15 #define __USE_ISOC99
  16 #include <limits.h>
  17 #include "parse.h"
  18 #include "smatch.h"
  19 #include "smatch_slist.h"
  20 #include "smatch_extra.h"
  21
  22 static int my_id;
  23
  24 static struct symbol *cur_func;
  25
  26 struct data_range whole_range = {
  27         .min = LLONG_MIN,
  28         .max = LLONG_MAX,
  29 };
  30
  31 static struct smatch_state *alloc_extra_state_empty()
  32 {
  33         struct smatch_state *state;
  34         struct data_info *dinfo;
  35
  36         dinfo = __alloc_data_info(0);
  37         dinfo->type = DATA_RANGE;
  38         dinfo->value_ranges = NULL;
  39         state = __alloc_smatch_state(0);
  40         state->data = dinfo;
  41         return state;
  42 }
  43
  44 static struct smatch_state *alloc_extra_state_no_name(int val)
  45 {
  46         struct smatch_state *state;
  47
  48         state = __alloc_smatch_state(0);
  49         state->data = (void *)alloc_dinfo_range(val, val);
  50         return state;
  51 }
  52
  53 /* We do this because ->value_ranges is a list */
  54 struct smatch_state *extra_undefined()
  55 {
  56         struct data_info *dinfo;
  57         static struct smatch_state *ret;
  58         static struct symbol *prev_func;
  59
  60         if  (prev_func == cur_func)
  61                 return ret;
  62         prev_func = cur_func;
  63
  64         dinfo = alloc_dinfo_range(whole_range.min, whole_range.max);
  65         ret = __alloc_smatch_state(0);
  66         ret->name = "unknown";
  67         ret->data = dinfo;
  68         return ret;
  69 }
  70
  71 struct smatch_state *alloc_extra_state(int val)
  72 {
  73         struct smatch_state *state;
  74
  75         state = alloc_extra_state_no_name(val);
  76         state->name = show_ranges(((struct data_info *)state->data)->value_ranges);
  77         return state;
  78 }
  79
  80 struct smatch_state *alloc_extra_state_range(long long min, long long max)
  81 {
  82         struct smatch_state *state;
  83
  84         if (min == whole_range.min && max == whole_range.max)
  85                 return extra_undefined();
  86         state = __alloc_smatch_state(0);
  87         state->data = (void *)alloc_dinfo_range(min, max);
  88         state->name = show_ranges(((struct data_info *)state->data)->value_ranges);
  89         return state;
  90 }
  91
  92 struct smatch_state *alloc_extra_state_range_list(struct range_list *rl)
  93 {
  94         struct smatch_state *state;
  95
  96         state = __alloc_smatch_state(0);
  97         state->data = (void *)alloc_dinfo_range_list(rl);
  98         state->name = show_ranges(((struct data_info *)state->data)->value_ranges);
  99         return state;
 100 }
 101
 102 struct smatch_state *filter_range(struct smatch_state *orig,
 103                                  long long filter_min, long long filter_max)
 104 {
 105         struct smatch_state *ret;
 106         struct data_info *orig_info;
 107         struct data_info *ret_info;
 108
 109         if (!orig)
 110                 orig = extra_undefined();
 111         orig_info = (struct data_info *)orig->data;
 112         ret = alloc_extra_state_empty();
 113         ret_info = (struct data_info *)ret->data;
 114         ret_info->value_ranges = remove_range(orig_info->value_ranges, filter_min, filter_max);
 115         ret->name = show_ranges(ret_info->value_ranges);
 116         return ret;
 117 }
 118
 119 struct smatch_state *add_filter(struct smatch_state *orig, long long num)
 120 {
 121         return filter_range(orig, num, num);
 122 }
 123
 124 static struct smatch_state *merge_func(const char *name, struct symbol *sym,
 125                                        struct smatch_state *s1,
 126                                        struct smatch_state *s2)
 127 {
 128         struct data_info *info1 = (struct data_info *)s1->data;
 129         struct data_info *info2 = (struct data_info *)s2->data;
 130         struct data_info *ret_info;
 131         struct smatch_state *tmp;
 132         struct range_list *value_ranges;
 133
 134         value_ranges = range_list_union(info1->value_ranges, info2->value_ranges);
 135         tmp = alloc_extra_state_empty();
 136         ret_info = (struct data_info *)tmp->data;
 137         ret_info->value_ranges = value_ranges;
 138         tmp->name = show_ranges(ret_info->value_ranges);
 139         return tmp;
 140 }
 141
 142 struct sm_state *__extra_pre_loop_hook_before(struct statement *iterator_pre_statement)
 143 {
 144         struct expression *expr;
 145         char *name;
 146         struct symbol *sym;
 147         struct sm_state *ret = NULL;
 148
 149         if (!iterator_pre_statement)
 150                 return NULL;
 151         if (iterator_pre_statement->type != STMT_EXPRESSION)
 152                 return NULL;
 153         expr = iterator_pre_statement->expression;
 154         if (expr->type != EXPR_ASSIGNMENT)
 155                 return NULL;
 156         name = get_variable_from_expr(expr->left, &sym);
 157         if (!name || !sym)
 158                 goto free;
 159         ret = get_sm_state(my_id, name, sym);
 160 free:
 161         free_string(name);
 162         return ret;
 163 }
 164
 165 int __iterator_unchanged(struct sm_state *sm, struct statement *iterator)
 166 {
 167         struct expression *iter_expr;
 168         char *name;
 169         struct symbol *sym;
 170         int ret = 0;
 171
 172         if (!iterator)
 173                 return 0;
 174         if (iterator->type != STMT_EXPRESSION)
 175                 return 0;
 176         iter_expr = iterator->expression;
 177         if (iter_expr->op != SPECIAL_INCREMENT && iter_expr->op != SPECIAL_DECREMENT)
 178                 return 0;
 179         name = get_variable_from_expr(iter_expr->unop, &sym);
 180         if (!name || !sym)
 181                 goto free;
 182         if (get_sm_state(my_id, name, sym) == sm)
 183                 ret = 1;
 184 free:
 185         free_string(name);
 186         return ret;
 187 }
 188
 189 void __extra_pre_loop_hook_after(struct sm_state *sm,
 190                                 struct statement *iterator,
 191                                 struct expression *condition)
 192 {
 193         struct expression *iter_expr;
 194         char *name;
 195         struct symbol *sym;
 196         long long value;
 197         int left = 0;
 198         struct smatch_state *state;
 199         struct data_info *dinfo;
 200         long long min, max;
 201
 202         iter_expr = iterator->expression;
 203
 204         if (condition->type != EXPR_COMPARE)
 205                 return;
 206         if (!get_value(condition->left, &value)) {
 207                 if (!get_value(condition->right, &value))
 208                         return;
 209                 left = 1;
 210         }
 211         if (left)
 212                 name = get_variable_from_expr(condition->left, &sym);
 213         else
 214                 name = get_variable_from_expr(condition->right, &sym);
 215         if (!name || !sym)
 216                 goto free;
 217         if (sym != sm->sym || strcmp(name, sm->name))
 218                 goto free;
 219         state = get_state(my_id, name, sym);
 220         dinfo = (struct data_info *)state->data;
 221         min = get_dinfo_min(dinfo);
 222         max = get_dinfo_max(dinfo);
 223         if (iter_expr->op == SPECIAL_INCREMENT && min != whole_range.min && max == whole_range.max) {
 224                 set_state(my_id, name, sym, alloc_extra_state(min));
 225         } else if (min == whole_range.min && max != whole_range.max) {
 226                 set_state(my_id, name, sym, alloc_extra_state(max));
 227         }
 228 free:
 229         free_string(name);
 230         return;
 231 }
 232
 233 static struct smatch_state *unmatched_state(struct sm_state *sm)
 234 {
 235         return extra_undefined();
 236 }
 237
 238 static void match_function_call(struct expression *expr)
 239 {
 240         struct expression *tmp;
 241         struct symbol *sym;
 242         char *name;
 243         int i = 0;
 244
 245         FOR_EACH_PTR(expr->args, tmp) {
 246                 if (tmp->type == EXPR_PREOP && tmp->op == '&') {
 247                         name = get_variable_from_expr(tmp->unop, &sym);
 248                         if (name) {
 249                                 set_state(my_id, name, sym, extra_undefined());
 250                         }
 251                         free_string(name);
 252                 }
 253                 i++;
 254         } END_FOR_EACH_PTR(tmp);
 255 }
 256
 257 static void match_assign(struct expression *expr)
 258 {
 259         struct expression *left;
 260         struct expression *right;
 261         struct symbol *sym;
 262         char *name;
 263         long long value;
 264         int known;
 265         long long min = whole_range.min;
 266         long long max = whole_range.max;
 267         long long tmp;
 268         struct range_list *rl = NULL;
 269
 270         left = strip_expr(expr->left);
 271         name = get_variable_from_expr(left, &sym);
 272         if (!name)
 273                 return;
 274         right = strip_expr(expr->right);
 275         while (right->type == EXPR_ASSIGNMENT && right->op == '=')
 276                 right = strip_expr(right->left);
 277
 278         known = get_implied_range_list(right, &rl);
 279         if (expr->op == '=') {
 280                 if (known)
 281                         set_state(my_id, name, sym, alloc_extra_state_range_list(rl));
 282                 else
 283                         set_state(my_id, name, sym, extra_undefined());
 284                 goto free;
 285         }
 286
 287         known = get_implied_value(right, &value);
 288         if (expr->op == SPECIAL_ADD_ASSIGN) {
 289                 if (get_implied_min(left, &tmp)) {
 290                         if (known)
 291                                 min = tmp + value;
 292                         else
 293                                 min = tmp;
 294                 }
 295
 296         }
 297         if (expr->op == SPECIAL_SUB_ASSIGN) {
 298                 if (get_implied_max(left, &tmp)) {
 299                         if (known)
 300                                 max = tmp - value;
 301                         else
 302                                 max = tmp;
 303                 }
 304
 305         }
 306         set_state(my_id, name, sym, alloc_extra_state_range(min, max));
 307 free:
 308         free_string(name);
 309 }
 310
 311 static void unop_expr(struct expression *expr)
 312 {
 313         struct symbol *sym;
 314         char *name;
 315         long long min = whole_range.min;
 316         long long max = whole_range.max;
 317         long long val;
 318
 319         if (expr->op == '*')
 320                 return;
 321         if (expr->op == '(')
 322                 return;
 323
 324         name = get_variable_from_expr(expr->unop, &sym);
 325         if (!name)
 326                 goto free;
 327         if (expr->op == SPECIAL_INCREMENT) {
 328                 if (get_implied_min(expr->unop, &val))
 329                         min = val + 1;
 330         }
 331         if (expr->op == SPECIAL_DECREMENT) {
 332                 if (get_implied_max(expr->unop, &val))
 333                         max = val - 1;
 334         }
 335         set_state(my_id, name, sym, alloc_extra_state_range(min, max));
 336 free:
 337         free_string(name);
 338 }
 339
 340 static void match_declarations(struct symbol *sym)
 341 {
 342         const char *name;
 343         long long val;
 344
 345         if (sym->ident) {
 346                 name = sym->ident->name;
 347                 if (sym->initializer) {
 348                         if (get_value(sym->initializer, &val))
 349                                 set_state(my_id, name, sym, alloc_extra_state(val));
 350                         else
 351                                 set_state(my_id, name, sym, extra_undefined());
 352                         scoped_state(my_id, name, sym);
 353                 } else {
 354                         set_state(my_id, name, sym, extra_undefined());
 355                         scoped_state(my_id, name, sym);
 356                 }
 357         }
 358 }
 359
 360 static void match_function_def(struct symbol *sym)
 361 {
 362         struct symbol *arg;
 363
 364         cur_func = sym;
 365         FOR_EACH_PTR(sym->ctype.base_type->arguments, arg) {
 366                 if (!arg->ident) {
 367                         continue;
 368                 }
 369                 set_state(my_id, arg->ident->name, arg, extra_undefined());
 370         } END_FOR_EACH_PTR(arg);
 371 }
 372
 373 #define VAL_SINGLE 0
 374 #define VAL_MAX    1
 375 #define VAL_MIN    2
 376
 377 static int get_implied_value_helper(struct expression *expr, long long *val, int what)
 378 {
 379         struct smatch_state *state;
 380         struct symbol *sym;
 381         char *name;
 382
 383         if (get_value(expr, val))
 384                 return 1;
 385
 386         name = get_variable_from_expr(expr, &sym);
 387         if (!name)
 388                 return 0;
 389         state = get_state(my_id, name, sym);
 390         free_string(name);
 391         if (!state || !state->data)
 392                 return 0;
 393         if (what == VAL_SINGLE)
 394                 return get_single_value_from_range((struct data_info *)state->data, val);
 395         if (what == VAL_MAX) {
 396                 *val = get_dinfo_max((struct data_info *)state->data);
 397                 if (*val == whole_range.max) /* this means just guessing */
 398                         return 0;
 399                 return 1;
 400         }
 401         *val = get_dinfo_min((struct data_info *)state->data);
 402         if (*val == whole_range.min)
 403                 return 0;
 404         return 1;
 405 }
 406
 407 int get_implied_single_val(struct expression *expr, long long *val)
 408 {
 409         return get_implied_value_helper(expr, val, VAL_SINGLE);
 410 }
 411
 412 int get_implied_max(struct expression *expr, long long *val)
 413 {
 414         return get_implied_value_helper(expr, val, VAL_MAX);
 415 }
 416
 417 int get_implied_min(struct expression *expr, long long *val)
 418 {
 419         return get_implied_value_helper(expr, val, VAL_MIN);
 420 }
 421
 422 static int last_stmt_val(struct statement *stmt, long long *val)
 423 {
 424         struct expression *expr;
 425
 426         if (!stmt)
 427                 return 0;
 428
 429         stmt = last_ptr_list((struct ptr_list *)stmt->stmts);
 430         if (stmt->type != STMT_EXPRESSION)
 431                 return 0;
 432         expr = stmt->expression;
 433         return get_value(expr, val);
 434 }
 435
 436 static void match_comparison(struct expression *expr)
 437 {
 438         long long fixed;
 439         char *name = NULL;
 440         struct symbol *sym;
 441         struct smatch_state *one_state;
 442         struct smatch_state *two_state;
 443         struct smatch_state *orig;
 444         int left = 0;
 445         int comparison = expr->op;
 446         struct expression *varies = expr->right;
 447
 448         if (!get_value(expr->left, &fixed)) {
 449                 if (!get_value(expr->right, &fixed))
 450                         return;
 451                 varies = expr->left;
 452                 left = 1;
 453         }
 454         if (varies->op == SPECIAL_INCREMENT || varies->op == SPECIAL_DECREMENT)
 455                 varies = varies->unop;
 456         if (varies->type == EXPR_CALL) {
 457                 function_comparison(comparison, varies, fixed, left);
 458                 return;
 459         }
 460
 461         name = get_variable_from_expr(varies, &sym);
 462         if (!name || !sym)
 463                 goto free;
 464
 465         orig = get_state(my_id, name, sym);
 466         if (!orig)
 467                 orig = extra_undefined();
 468
 469         switch(comparison){
 470         case '<':
 471         case SPECIAL_UNSIGNED_LT:
 472                 one_state = filter_range(orig, whole_range.min, fixed - 1);
 473                 two_state = filter_range(orig, fixed, whole_range.max);
 474                 if (left)
 475                         set_true_false_states(my_id, name, sym, two_state, one_state);
 476                 else
 477                         set_true_false_states(my_id, name, sym, one_state, two_state);
 478                 return;
 479         case SPECIAL_UNSIGNED_LTE:
 480         case SPECIAL_LTE:
 481                 one_state = filter_range(orig, whole_range.min, fixed);
 482                 two_state = filter_range(orig, fixed + 1, whole_range.max);
 483                 if (left)
 484                         set_true_false_states(my_id, name, sym, two_state, one_state);
 485                 else
 486                         set_true_false_states(my_id, name, sym, one_state, two_state);
 487                 return;
 488         case SPECIAL_EQUAL:
 489                 // todo.  print a warning here for impossible conditions.
 490                 one_state = alloc_extra_state(fixed);
 491                 two_state = filter_range(orig, fixed, fixed);
 492                 set_true_false_states(my_id, name, sym, one_state, two_state);
 493                 return;
 494         case SPECIAL_UNSIGNED_GTE:
 495         case SPECIAL_GTE:
 496                 one_state = filter_range(orig, whole_range.min, fixed - 1);
 497                 two_state = filter_range(orig, fixed, whole_range.max);
 498                 if (left)
 499                         set_true_false_states(my_id, name, sym, one_state, two_state);
 500                 else
 501                         set_true_false_states(my_id, name, sym, two_state, one_state);
 502                 return;
 503         case '>':
 504         case SPECIAL_UNSIGNED_GT:
 505                 one_state = filter_range(orig, whole_range.min, fixed);
 506                 two_state = filter_range(orig, fixed + 1, whole_range.max);
 507                 if (left)
 508                         set_true_false_states(my_id, name, sym, one_state, two_state);
 509                 else
 510                         set_true_false_states(my_id, name, sym, two_state, one_state);
 511                 return;
 512         case SPECIAL_NOTEQUAL:
 513                 one_state = alloc_extra_state(fixed);
 514                 two_state = filter_range(orig, fixed, fixed);
 515                 set_true_false_states(my_id, name, sym, two_state, one_state);
 516                 return;
 517         default:
 518                 sm_msg("unhandled comparison %d\n", comparison);
 519                 return;
 520         }
 521         return;
 522 free:
 523         free_string(name);
 524 }
 525
 526 /* this is actually hooked from smatch_implied.c...  it's hacky, yes */
 527 void __extra_match_condition(struct expression *expr)
 528 {
 529         struct symbol *sym;
 530         char *name;
 531         struct smatch_state *pre_state;
 532         struct smatch_state *true_state;
 533         struct smatch_state *false_state;
 534
 535         expr = strip_expr(expr);
 536         switch(expr->type) {
 537         case EXPR_CALL:
 538                 function_comparison(SPECIAL_NOTEQUAL, expr, 0, 1);
 539                 return;
 540         case EXPR_PREOP:
 541         case EXPR_SYMBOL:
 542         case EXPR_DEREF:
 543                 name = get_variable_from_expr(expr, &sym);
 544                 if (!name)
 545                         return;
 546                 pre_state = get_state(my_id, name, sym);
 547                 true_state = add_filter(pre_state, 0);
 548                 false_state = alloc_extra_state(0);
 549                 set_true_false_states(my_id, name, sym, true_state, false_state);
 550                 free_string(name);
 551                 return;
 552         case EXPR_COMPARE:
 553                 match_comparison(expr);
 554                 return;
 555         case EXPR_ASSIGNMENT:
 556                 __extra_match_condition(expr->left);
 557                 return;
 558         }
 559 }
 560
 561 /* returns 1 if it is not possible for expr to be value, otherwise returns 0 */
 562 int implied_not_equal(struct expression *expr, long long val)
 563 {
 564         char *name;
 565         struct symbol *sym;
 566         struct smatch_state *state;
 567         int ret = 0;
 568
 569         name = get_variable_from_expr(expr, &sym);
 570         if (!name || !sym)
 571                 goto exit;
 572         state = get_state(my_id, name, sym);
 573         if (!state || !state->data)
 574                 goto exit;
 575         ret = !possibly_false(SPECIAL_NOTEQUAL, (struct data_info *)state->data, val, 1);
 576 exit:
 577         free_string(name);
 578         return ret;
 579 }
 580
 581 int known_condition_true(struct expression *expr)
 582 {
 583         long long tmp;
 584
 585         if (!expr)
 586                 return 0;
 587
 588         if (get_value(expr, &tmp) && tmp)
 589                 return 1;
 590
 591         expr = strip_expr(expr);
 592         switch(expr->type) {
 593         case EXPR_PREOP:
 594                 if (expr->op == '!') {
 595                         if (known_condition_false(expr->unop))
 596                                 return 1;
 597                         break;
 598                 }
 599                 break;
 600         default:
 601                 break;
 602         }
 603         return 0;
 604 }
 605
 606 int known_condition_false(struct expression *expr)
 607 {
 608         if (!expr)
 609                 return 0;
 610
 611         if (is_zero(expr))
 612                 return 1;
 613
 614         switch(expr->type) {
 615         case EXPR_PREOP:
 616                 if (expr->op == '!') {
 617                         if (known_condition_true(expr->unop))
 618                                 return 1;
 619                         break;
 620                 }
 621                 break;
 622         default:
 623                 break;
 624         }
 625         return 0;
 626 }
 627
 628 static int do_comparison_range(struct expression *expr)
 629 {
 630         struct symbol *sym;
 631         char *name;
 632         struct smatch_state *state;
 633         long long value;
 634         int left = 0;
 635         int poss_true, poss_false;
 636
 637         if (!get_value(expr->left, &value)) {
 638                 if (!get_value(expr->right, &value))
 639                         return 3;
 640                 left = 1;
 641         }
 642         if (left)
 643                 name = get_variable_from_expr(expr->left, &sym);
 644         else
 645                 name = get_variable_from_expr(expr->right, &sym);
 646         if (!name || !sym)
 647                 goto free;
 648         state = get_state(SMATCH_EXTRA, name, sym);
 649         if (!state)
 650                 goto free;
 651         poss_true = possibly_true(expr->op, (struct data_info *)state->data, value, left);
 652         poss_false = possibly_false(expr->op, (struct data_info *)state->data, value, left);
 653         if (!poss_true && !poss_false)
 654                 return 0;
 655         if (poss_true && !poss_false)
 656                 return 1;
 657         if (!poss_true && poss_false)
 658                 return 2;
 659         if (poss_true && poss_false)
 660                 return 3;
 661 free:
 662         free_string(name);
 663         return 3;
 664 }
 665
 666 int implied_condition_true(struct expression *expr)
 667 {
 668         struct statement *stmt;
 669         long long tmp;
 670         long long val;
 671
 672         if (!expr)
 673                 return 0;
 674
 675         if (get_value(expr, &tmp) && tmp)
 676                 return 1;
 677
 678         expr = strip_expr(expr);
 679         switch(expr->type) {
 680         case EXPR_COMPARE:
 681                 if (do_comparison_range(expr) == 1)
 682                         return 1;
 683                 break;
 684         case EXPR_PREOP:
 685                 if (expr->op == '!') {
 686                         if (implied_condition_false(expr->unop))
 687                                 return 1;
 688                         break;
 689                 }
 690                 stmt = get_block_thing(expr);
 691                 if (last_stmt_val(stmt, &val) && val == 1)
 692                         return 1;
 693                 break;
 694         default:
 695                 if (implied_not_equal(expr, 0) == 1)
 696                         return 1;
 697                 break;
 698         }
 699         return 0;
 700 }
 701
 702 int implied_condition_false(struct expression *expr)
 703 {
 704         struct statement *stmt;
 705         struct expression *tmp;
 706         long long val;
 707
 708         if (!expr)
 709                 return 0;
 710
 711         if (is_zero(expr))
 712                 return 1;
 713
 714         switch(expr->type) {
 715         case EXPR_COMPARE:
 716                 if (do_comparison_range(expr) == 2)
 717                         return 1;
 718         case EXPR_PREOP:
 719                 if (expr->op == '!') {
 720                         if (implied_condition_true(expr->unop))
 721                                 return 1;
 722                         break;
 723                 }
 724                 stmt = get_block_thing(expr);
 725                 if (last_stmt_val(stmt, &val) && val == 0)
 726                         return 1;
 727                 tmp = strip_expr(expr);
 728                 if (tmp != expr)
 729                         return implied_condition_false(tmp);
 730                 break;
 731         default:
 732                 if (get_implied_value(expr, &val) && val == 0)
 733                         return 1;
 734                 break;
 735         }
 736         return 0;
 737 }
 738
 739 int get_implied_range_list(struct expression *expr, struct range_list **rl)
 740 {
 741         long long val;
 742         struct smatch_state *state;
 743
 744         expr = strip_expr(expr);
 745
 746         state = get_state_expr(my_id, expr);
 747         if (state) {
 748                 *rl = clone_range_list(((struct data_info *)state->data)->value_ranges);
 749                 return 1;
 750         }
 751
 752         if (get_implied_value(expr, &val)) {
 753                 *rl = NULL;
 754                 add_range(rl, val, val);
 755                 return 1;
 756         }
 757
 758         if (expr->type == EXPR_BINOP && expr->op == '%') {
 759                 if (!get_implied_value(expr->right, &val))
 760                         return 0;
 761                 *rl = NULL;
 762                 add_range(rl, 0, val - 1);
 763                 return 1;
 764         }
 765
 766         return 0;
 767 }
 768
 769 void register_smatch_extra(int id)
 770 {
 771         my_id = id;
 772         add_merge_hook(my_id, &merge_func);
 773         add_unmatched_state_hook(my_id, &unmatched_state);
 774         add_hook(&unop_expr, OP_HOOK);
 775         add_hook(&match_function_def, FUNC_DEF_HOOK);
 776         add_hook(&match_function_call, FUNCTION_CALL_HOOK);
 777         add_hook(&match_assign, ASSIGNMENT_HOOK);
 778         add_hook(&match_declarations, DECLARATION_HOOK);
 779
 780         if (option_project == PROJ_KERNEL) {
 781                 /* I don't know how to test for the ATTRIB_NORET attribute. :( */
 782                 add_function_hook("panic", &__match_nullify_path_hook, NULL);
 783                 add_function_hook("do_exit", &__match_nullify_path_hook, NULL);
 784                 add_function_hook("complete_and_exit", &__match_nullify_path_hook, NULL);
 785                 add_function_hook("__module_put_and_exit", &__match_nullify_path_hook, NULL);
 786                 add_function_hook("do_group_exit", &__match_nullify_path_hook, NULL);
 787         }
 788 }