smatch_math.c

   1 /*
   2  * Copyright (C) 2010 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 #include "symbol.h"
  19 #include "smatch.h"
  20 #include "smatch_slist.h"
  21 #include "smatch_extra.h"
  22
  23 static struct range_list *_get_rl(struct expression *expr, int implied, int *recurse_cnt);
  24 static struct range_list *handle_variable(struct expression *expr, int implied, int *recurse_cnt);
  25 static struct range_list *(*custom_handle_variable)(struct expression *expr);
  26
  27 static int get_implied_value_internal(struct expression *expr, sval_t *sval, int *recurse_cnt);
  28 static int get_absolute_rl_internal(struct expression *expr, struct range_list **rl, int *recurse_cnt);
  29
  30 static sval_t zero  = {.type = &int_ctype, {.value = 0} };
  31 static sval_t one   = {.type = &int_ctype, {.value = 1} };
  32
  33 struct range_list *rl_zero(void)
  34 {
  35         static struct range_list *zero_perm;
  36
  37         if (!zero_perm)
  38                 zero_perm = clone_rl_permanent(alloc_rl(zero, zero));
  39         return zero_perm;
  40 }
  41
  42 struct range_list *rl_one(void)
  43 {
  44         static struct range_list *one_perm;
  45
  46         if (!one_perm)
  47                 one_perm = clone_rl_permanent(alloc_rl(one, one));
  48
  49         return one_perm;
  50 }
  51
  52 enum {
  53         RL_EXACT,
  54         RL_HARD,
  55         RL_FUZZY,
  56         RL_IMPLIED,
  57         RL_ABSOLUTE,
  58         RL_REAL_ABSOLUTE,
  59 };
  60
  61 static struct range_list *last_stmt_rl(struct statement *stmt, int implied, int *recurse_cnt)
  62 {
  63         struct expression *expr;
  64
  65         if (!stmt)
  66                 return NULL;
  67
  68         stmt = last_ptr_list((struct ptr_list *)stmt->stmts);
  69         if (stmt->type == STMT_LABEL) {
  70                 if (stmt->label_statement &&
  71                     stmt->label_statement->type == STMT_EXPRESSION)
  72                         expr = stmt->label_statement->expression;
  73                 else
  74                         return NULL;
  75         } else if (stmt->type == STMT_EXPRESSION) {
  76                 expr = stmt->expression;
  77         } else {
  78                 return NULL;
  79         }
  80         return _get_rl(expr, implied, recurse_cnt);
  81 }
  82
  83 static struct range_list *handle_expression_statement_rl(struct expression *expr, int implied, int *recurse_cnt)
  84 {
  85         return last_stmt_rl(get_expression_statement(expr), implied, recurse_cnt);
  86 }
  87
  88 static struct range_list *handle_ampersand_rl(struct expression *expr, int implied, int *recurse_cnt)
  89 {
  90         struct range_list *rl;
  91         sval_t sval;
  92
  93         if (implied == RL_EXACT || implied == RL_HARD)
  94                 return NULL;
  95         if (get_mtag_sval(expr, &sval))
  96                 return alloc_rl(sval, sval);
  97         if (get_address_rl(expr, &rl))
  98                 return rl;
  99         return alloc_rl(valid_ptr_min_sval, valid_ptr_max_sval);
 100 }
 101
 102 static struct range_list *handle_negate_rl(struct expression *expr, int implied, int *recurse_cnt)
 103 {
 104         if (known_condition_true(expr->unop))
 105                 return rl_zero();
 106         if (known_condition_false(expr->unop))
 107                 return rl_one();
 108
 109         if (implied == RL_EXACT)
 110                 return NULL;
 111
 112         if (implied_condition_true(expr->unop))
 113                 return rl_zero();
 114         if (implied_condition_false(expr->unop))
 115                 return rl_one();
 116         return alloc_rl(zero, one);
 117 }
 118
 119 static struct range_list *handle_bitwise_negate(struct expression *expr, int implied, int *recurse_cnt)
 120 {
 121         struct range_list *rl;
 122         sval_t sval;
 123
 124         rl = _get_rl(expr->unop, implied, recurse_cnt);
 125         if (!rl_to_sval(rl, &sval))
 126                 return NULL;
 127         sval = sval_preop(sval, '~');
 128         sval_cast(get_type(expr->unop), sval);
 129         return alloc_rl(sval, sval);
 130 }
 131
 132 static struct range_list *handle_minus_preop(struct expression *expr, int implied, int *recurse_cnt)
 133 {
 134         struct range_list *rl;
 135         sval_t min, max;
 136
 137         rl = _get_rl(expr->unop, implied, recurse_cnt);
 138         min = sval_preop(rl_max(rl), '-');
 139         max = sval_preop(rl_min(rl), '-');
 140         return alloc_rl(min, max);
 141 }
 142
 143 static struct range_list *handle_preop_rl(struct expression *expr, int implied, int *recurse_cnt)
 144 {
 145         switch (expr->op) {
 146         case '&':
 147                 return handle_ampersand_rl(expr, implied, recurse_cnt);
 148         case '!':
 149                 return handle_negate_rl(expr, implied, recurse_cnt);
 150         case '~':
 151                 return handle_bitwise_negate(expr, implied, recurse_cnt);
 152         case '-':
 153                 return handle_minus_preop(expr, implied, recurse_cnt);
 154         case '*':
 155                 return handle_variable(expr, implied, recurse_cnt);
 156         case '(':
 157                 return handle_expression_statement_rl(expr, implied, recurse_cnt);
 158         default:
 159                 return NULL;
 160         }
 161 }
 162
 163 static struct range_list *handle_divide_rl(struct expression *expr, int implied, int *recurse_cnt)
 164 {
 165         struct range_list *left_rl, *right_rl;
 166         struct symbol *type;
 167
 168         type = get_type(expr);
 169
 170         left_rl = _get_rl(expr->left, implied, recurse_cnt);
 171         left_rl = cast_rl(type, left_rl);
 172         right_rl = _get_rl(expr->right, implied, recurse_cnt);
 173         right_rl = cast_rl(type, right_rl);
 174
 175         if (!left_rl || !right_rl)
 176                 return NULL;
 177
 178         if (implied != RL_REAL_ABSOLUTE) {
 179                 if (is_whole_rl(left_rl) || is_whole_rl(right_rl))
 180                         return NULL;
 181         }
 182
 183         return rl_binop(left_rl, '/', right_rl);
 184 }
 185
 186 static int handle_offset_subtraction(struct expression *expr)
 187 {
 188         struct expression *left, *right;
 189         struct symbol *left_sym, *right_sym;
 190         struct symbol *type;
 191         int left_offset, right_offset;
 192
 193         type = get_type(expr);
 194         if (!type || type->type != SYM_PTR)
 195                 return -1;
 196         type = get_real_base_type(type);
 197         if (!type || (type_bits(type) != 8 && (type != &void_ctype)))
 198                 return -1;
 199
 200         left = strip_expr(expr->left);
 201         right = strip_expr(expr->right);
 202
 203         if (left->type != EXPR_PREOP || left->op != '&')
 204                 return -1;
 205         left = strip_expr(left->unop);
 206
 207         left_sym = expr_to_sym(left);
 208         right_sym = expr_to_sym(right);
 209         if (!left_sym || left_sym != right_sym)
 210                 return -1;
 211
 212         left_offset = get_member_offset_from_deref(left);
 213         if (right->type == EXPR_SYMBOL)
 214                 right_offset = 0;
 215         else {
 216                 if (right->type != EXPR_PREOP || right->op != '&')
 217                         return -1;
 218                 right = strip_expr(right->unop);
 219                 right_offset = get_member_offset_from_deref(right);
 220         }
 221         if (left_offset < 0 || right_offset < 0)
 222                 return -1;
 223
 224         return left_offset - right_offset;
 225 }
 226
 227 static struct range_list *handle_subtract_rl(struct expression *expr, int implied, int *recurse_cnt)
 228 {
 229         struct symbol *type;
 230         struct range_list *left_orig, *right_orig;
 231         struct range_list *left_rl, *right_rl;
 232         sval_t max, min, tmp;
 233         int comparison;
 234         int offset;
 235
 236         type = get_type(expr);
 237
 238         offset = handle_offset_subtraction(expr);
 239         if (offset >= 0) {
 240                 tmp.type = type;
 241                 tmp.value = offset;
 242
 243                 return alloc_rl(tmp, tmp);
 244         }
 245
 246         comparison = get_comparison(expr->left, expr->right);
 247
 248         left_orig = _get_rl(expr->left, implied, recurse_cnt);
 249         left_rl = cast_rl(type, left_orig);
 250         right_orig = _get_rl(expr->right, implied, recurse_cnt);
 251         right_rl = cast_rl(type, right_orig);
 252
 253         if ((!left_rl || !right_rl) &&
 254             (implied == RL_EXACT || implied == RL_HARD || implied == RL_FUZZY))
 255                 return NULL;
 256
 257         if (!left_rl)
 258                 left_rl = alloc_whole_rl(type);
 259         if (!right_rl)
 260                 right_rl = alloc_whole_rl(type);
 261
 262         /* negative values complicate everything fix this later */
 263         if (sval_is_negative(rl_min(right_rl)))
 264                 return NULL;
 265         max = rl_max(left_rl);
 266         min = sval_type_min(type);
 267
 268         switch (comparison) {
 269         case '>':
 270         case SPECIAL_UNSIGNED_GT:
 271                 min = sval_type_val(type, 1);
 272                 max = rl_max(left_rl);
 273                 break;
 274         case SPECIAL_GTE:
 275         case SPECIAL_UNSIGNED_GTE:
 276                 min = sval_type_val(type, 0);
 277                 max = rl_max(left_rl);
 278                 break;
 279         case SPECIAL_EQUAL:
 280                 min = sval_type_val(type, 0);
 281                 max = sval_type_val(type, 0);
 282                 break;
 283         case '<':
 284         case SPECIAL_UNSIGNED_LT:
 285                 max = sval_type_val(type, -1);
 286                 break;
 287         case SPECIAL_LTE:
 288         case SPECIAL_UNSIGNED_LTE:
 289                 max = sval_type_val(type, 0);
 290                 break;
 291         default:
 292                 if (!left_orig || !right_orig)
 293                         return NULL;
 294                 return rl_binop(left_rl, '-', right_rl);
 295         }
 296
 297         if (!sval_binop_overflows(rl_min(left_rl), '-', rl_max(right_rl))) {
 298                 tmp = sval_binop(rl_min(left_rl), '-', rl_max(right_rl));
 299                 if (sval_cmp(tmp, min) > 0)
 300                         min = tmp;
 301         }
 302
 303         if (!sval_is_max(rl_max(left_rl))) {
 304                 tmp = sval_binop(rl_max(left_rl), '-', rl_min(right_rl));
 305                 if (sval_cmp(tmp, max) < 0)
 306                         max = tmp;
 307         }
 308
 309         if (sval_is_min(min) && sval_is_max(max))
 310                 return NULL;
 311
 312         return cast_rl(type, alloc_rl(min, max));
 313 }
 314
 315 static struct range_list *handle_mod_rl(struct expression *expr, int implied, int *recurse_cnt)
 316 {
 317         struct range_list *rl;
 318         sval_t left, right, sval;
 319
 320         if (implied == RL_EXACT) {
 321                 if (!get_implied_value(expr->right, &right))
 322                         return NULL;
 323                 if (!get_implied_value(expr->left, &left))
 324                         return NULL;
 325                 sval = sval_binop(left, '%', right);
 326                 return alloc_rl(sval, sval);
 327         }
 328         /* if we can't figure out the right side it's probably hopeless */
 329         if (!get_implied_value_internal(expr->right, &right, recurse_cnt))
 330                 return NULL;
 331
 332         right = sval_cast(get_type(expr), right);
 333         right.value--;
 334
 335         rl = _get_rl(expr->left, implied, recurse_cnt);
 336         if (rl && rl_max(rl).uvalue < right.uvalue)
 337                 right.uvalue = rl_max(rl).uvalue;
 338
 339         return alloc_rl(sval_cast(right.type, zero), right);
 340 }
 341
 342 static sval_t sval_lowest_set_bit(sval_t sval)
 343 {
 344         int i;
 345         int found = 0;
 346
 347         for (i = 0; i < 64; i++) {
 348                 if (sval.uvalue & 1ULL << i) {
 349                         if (!found++)
 350                                 continue;
 351                         sval.uvalue &= ~(1ULL << i);
 352                 }
 353         }
 354         return sval;
 355 }
 356
 357 static struct range_list *handle_bitwise_AND(struct expression *expr, int implied, int *recurse_cnt)
 358 {
 359         struct symbol *type;
 360         struct range_list *left_rl, *right_rl;
 361         sval_t known;
 362         int new_recurse;
 363
 364         if (implied != RL_IMPLIED && implied != RL_ABSOLUTE && implied != RL_REAL_ABSOLUTE)
 365                 return NULL;
 366
 367         type = get_type(expr);
 368
 369         if (get_implied_value_internal(expr->left, &known, recurse_cnt)) {
 370                 sval_t min;
 371
 372                 min = sval_lowest_set_bit(known);
 373                 left_rl = alloc_rl(min, known);
 374                 left_rl = cast_rl(type, left_rl);
 375                 add_range(&left_rl, sval_type_val(type, 0), sval_type_val(type, 0));
 376         } else {
 377                 left_rl = _get_rl(expr->left, implied, recurse_cnt);
 378                 if (left_rl) {
 379                         left_rl = cast_rl(type, left_rl);
 380                         left_rl = alloc_rl(sval_type_val(type, 0), rl_max(left_rl));
 381                 } else {
 382                         if (implied == RL_HARD)
 383                                 return NULL;
 384                         left_rl = alloc_whole_rl(type);
 385                 }
 386         }
 387
 388         new_recurse = *recurse_cnt;
 389         if (*recurse_cnt >= 200)
 390                 new_recurse = 100;  /* Let's try super hard to get the mask */
 391         if (get_implied_value_internal(expr->right, &known, &new_recurse)) {
 392                 sval_t min, left_max, mod;
 393
 394                 *recurse_cnt = new_recurse;
 395
 396                 min = sval_lowest_set_bit(known);
 397                 right_rl = alloc_rl(min, known);
 398                 right_rl = cast_rl(type, right_rl);
 399                 add_range(&right_rl, sval_type_val(type, 0), sval_type_val(type, 0));
 400
 401                 if (min.value != 0) {
 402                         left_max = rl_max(left_rl);
 403                         mod = sval_binop(left_max, '%', min);
 404                         if (mod.value) {
 405                                 left_max = sval_binop(left_max, '-', mod);
 406                                 left_max.value++;
 407                                 if (left_max.value > 0 && sval_cmp(left_max, rl_max(left_rl)) < 0)
 408                                         left_rl = remove_range(left_rl, left_max, rl_max(left_rl));
 409                         }
 410                 }
 411         } else {
 412                 right_rl = _get_rl(expr->right, implied, recurse_cnt);
 413                 if (right_rl) {
 414                         right_rl = cast_rl(type, right_rl);
 415                         right_rl = alloc_rl(sval_type_val(type, 0), rl_max(right_rl));
 416                 } else {
 417                         if (implied == RL_HARD)
 418                                 return NULL;
 419                         right_rl = alloc_whole_rl(type);
 420                 }
 421         }
 422
 423         return rl_intersection(left_rl, right_rl);
 424 }
 425
 426 static struct range_list *use_rl_binop(struct expression *expr, int implied, int *recurse_cnt)
 427 {
 428         struct symbol *type;
 429         struct range_list *left_rl, *right_rl;
 430
 431         if (implied != RL_IMPLIED && implied != RL_ABSOLUTE && implied != RL_REAL_ABSOLUTE)
 432                 return NULL;
 433
 434         type = get_type(expr);
 435
 436         get_absolute_rl_internal(expr->left, &left_rl, recurse_cnt);
 437         get_absolute_rl_internal(expr->right, &right_rl, recurse_cnt);
 438         left_rl = cast_rl(type, left_rl);
 439         right_rl = cast_rl(type, right_rl);
 440         if (!left_rl || !right_rl)
 441                 return NULL;
 442
 443         return rl_binop(left_rl, expr->op, right_rl);
 444 }
 445
 446 static struct range_list *handle_right_shift(struct expression *expr, int implied, int *recurse_cnt)
 447 {
 448         struct range_list *left_rl;
 449         sval_t right;
 450         sval_t min, max;
 451
 452         if (implied == RL_EXACT || implied == RL_HARD)
 453                 return NULL;
 454
 455         left_rl = _get_rl(expr->left, implied, recurse_cnt);
 456         if (left_rl) {
 457                 max = rl_max(left_rl);
 458                 min = rl_min(left_rl);
 459         } else {
 460                 if (implied == RL_FUZZY)
 461                         return NULL;
 462                 max = sval_type_max(get_type(expr->left));
 463                 min = sval_type_val(get_type(expr->left), 0);
 464         }
 465
 466         if (get_implied_value_internal(expr->right, &right, recurse_cnt)) {
 467                 min = sval_binop(min, SPECIAL_RIGHTSHIFT, right);
 468                 max = sval_binop(max, SPECIAL_RIGHTSHIFT, right);
 469         } else if (!sval_is_negative(min)) {
 470                 min.value = 0;
 471                 max = sval_type_max(max.type);
 472         } else {
 473                 return NULL;
 474         }
 475
 476         return alloc_rl(min, max);
 477 }
 478
 479 static struct range_list *handle_left_shift(struct expression *expr, int implied, int *recurse_cnt)
 480 {
 481         struct range_list *left_rl, *res;
 482         sval_t right;
 483         sval_t min, max;
 484         int add_zero = 0;
 485
 486         if (implied == RL_EXACT || implied == RL_HARD)
 487                 return NULL;
 488         /* this is hopeless without the right side */
 489         if (!get_implied_value_internal(expr->right, &right, recurse_cnt))
 490                 return NULL;
 491         left_rl = _get_rl(expr->left, implied, recurse_cnt);
 492         if (left_rl) {
 493                 max = rl_max(left_rl);
 494                 min = rl_min(left_rl);
 495                 if (min.value == 0) {
 496                         min.value = 1;
 497                         add_zero = 1;
 498                 }
 499         } else {
 500                 if (implied == RL_FUZZY)
 501                         return NULL;
 502                 max = sval_type_max(get_type(expr->left));
 503                 min = sval_type_val(get_type(expr->left), 1);
 504                 add_zero = 1;
 505         }
 506
 507         max = sval_binop(max, SPECIAL_LEFTSHIFT, right);
 508         min = sval_binop(min, SPECIAL_LEFTSHIFT, right);
 509         res = alloc_rl(min, max);
 510         if (add_zero)
 511                 res = rl_union(res, rl_zero());
 512         return res;
 513 }
 514
 515 static struct range_list *handle_known_binop(struct expression *expr)
 516 {
 517         sval_t left, right;
 518
 519         if (!get_value(expr->left, &left))
 520                 return NULL;
 521         if (!get_value(expr->right, &right))
 522                 return NULL;
 523         left = sval_binop(left, expr->op, right);
 524         return alloc_rl(left, left);
 525 }
 526
 527 static int has_actual_ranges(struct range_list *rl)
 528 {
 529         struct data_range *tmp;
 530
 531         FOR_EACH_PTR(rl, tmp) {
 532                 if (sval_cmp(tmp->min, tmp->max) != 0)
 533                         return 1;
 534         } END_FOR_EACH_PTR(tmp);
 535         return 0;
 536 }
 537
 538 static struct range_list *handle_implied_binop(struct range_list *left_rl, int op, struct range_list *right_rl)
 539 {
 540         struct range_list *res_rl;
 541         struct data_range *left_drange, *right_drange;
 542         sval_t res;
 543
 544         if (!left_rl || !right_rl)
 545                 return NULL;
 546         if (has_actual_ranges(left_rl))
 547                 return NULL;
 548         if (has_actual_ranges(right_rl))
 549                 return NULL;
 550
 551         if (ptr_list_size((struct ptr_list *)left_rl) * ptr_list_size((struct ptr_list *)right_rl) > 20)
 552                 return NULL;
 553
 554         res_rl = NULL;
 555
 556         FOR_EACH_PTR(left_rl, left_drange) {
 557                 FOR_EACH_PTR(right_rl, right_drange) {
 558                         if ((op == '%' || op == '/') &&
 559                             right_drange->min.value == 0)
 560                                 return NULL;
 561                         res = sval_binop(left_drange->min, op, right_drange->min);
 562                         add_range(&res_rl, res, res);
 563                 } END_FOR_EACH_PTR(right_drange);
 564         } END_FOR_EACH_PTR(left_drange);
 565
 566         return res_rl;
 567 }
 568
 569 static struct range_list *handle_binop_rl(struct expression *expr, int implied, int *recurse_cnt)
 570 {
 571         struct smatch_state *state;
 572         struct symbol *type;
 573         struct range_list *left_rl, *right_rl, *rl;
 574         sval_t min, max;
 575
 576         rl = handle_known_binop(expr);
 577         if (rl)
 578                 return rl;
 579         if (implied == RL_EXACT)
 580                 return NULL;
 581
 582         if (custom_handle_variable) {
 583                 rl = custom_handle_variable(expr);
 584                 if (rl)
 585                         return rl;
 586         }
 587
 588         state = get_extra_state(expr);
 589         if (state && !is_whole_rl(estate_rl(state))) {
 590                 if (implied != RL_HARD || estate_has_hard_max(state))
 591                         return clone_rl(estate_rl(state));
 592         }
 593
 594         type = get_type(expr);
 595         left_rl = _get_rl(expr->left, implied, recurse_cnt);
 596         left_rl = cast_rl(type, left_rl);
 597         right_rl = _get_rl(expr->right, implied, recurse_cnt);
 598         right_rl = cast_rl(type, right_rl);
 599
 600         if (!left_rl && !right_rl)
 601                 return NULL;
 602
 603         rl = handle_implied_binop(left_rl, expr->op, right_rl);
 604         if (rl)
 605                 return rl;
 606
 607         switch (expr->op) {
 608         case '%':
 609                 return handle_mod_rl(expr, implied, recurse_cnt);
 610         case '&':
 611                 return handle_bitwise_AND(expr, implied, recurse_cnt);
 612         case '|':
 613         case '^':
 614                 return use_rl_binop(expr, implied, recurse_cnt);
 615         case SPECIAL_RIGHTSHIFT:
 616                 return handle_right_shift(expr, implied, recurse_cnt);
 617         case SPECIAL_LEFTSHIFT:
 618                 return handle_left_shift(expr, implied, recurse_cnt);
 619         case '-':
 620                 return handle_subtract_rl(expr, implied, recurse_cnt);
 621         case '/':
 622                 return handle_divide_rl(expr, implied, recurse_cnt);
 623         }
 624
 625         if (!left_rl || !right_rl)
 626                 return NULL;
 627
 628         if (sval_binop_overflows(rl_min(left_rl), expr->op, rl_min(right_rl)))
 629                 return NULL;
 630         if (sval_binop_overflows(rl_max(left_rl), expr->op, rl_max(right_rl)))
 631                 return NULL;
 632
 633         min = sval_binop(rl_min(left_rl), expr->op, rl_min(right_rl));
 634         max = sval_binop(rl_max(left_rl), expr->op, rl_max(right_rl));
 635
 636         return alloc_rl(min, max);
 637 }
 638
 639 static int do_comparison(struct expression *expr)
 640 {
 641         struct range_list *left_ranges = NULL;
 642         struct range_list *right_ranges = NULL;
 643         int poss_true, poss_false;
 644         struct symbol *type;
 645
 646         type = get_type(expr);
 647         get_absolute_rl(expr->left, &left_ranges);
 648         get_absolute_rl(expr->right, &right_ranges);
 649
 650         left_ranges = cast_rl(type, left_ranges);
 651         right_ranges = cast_rl(type, right_ranges);
 652
 653         poss_true = possibly_true_rl(left_ranges, expr->op, right_ranges);
 654         poss_false = possibly_false_rl(left_ranges, expr->op, right_ranges);
 655
 656         if (!poss_true && !poss_false)
 657                 return 0x0;
 658         if (poss_true && !poss_false)
 659                 return 0x1;
 660         if (!poss_true && poss_false)
 661                 return 0x2;
 662         return 0x3;
 663 }
 664
 665 static struct range_list *handle_comparison_rl(struct expression *expr, int implied, int *recurse_cnt)
 666 {
 667         sval_t left, right;
 668         int res;
 669
 670         if (expr->op == SPECIAL_EQUAL && expr->left->type == EXPR_TYPE) {
 671                 struct symbol *left, *right;
 672
 673                 left = get_real_base_type(expr->left->symbol);
 674                 right = get_real_base_type(expr->left->symbol);
 675                 if (left == right)
 676                         return rl_one();
 677                 return rl_zero();
 678         }
 679
 680         if (get_value(expr->left, &left) && get_value(expr->right, &right)) {
 681                 struct data_range tmp_left, tmp_right;
 682
 683                 tmp_left.min = left;
 684                 tmp_left.max = left;
 685                 tmp_right.min = right;
 686                 tmp_right.max = right;
 687                 if (true_comparison_range(&tmp_left, expr->op, &tmp_right))
 688                         return rl_one();
 689                 return rl_zero();
 690         }
 691
 692         if (implied == RL_EXACT)
 693                 return NULL;
 694
 695         res = do_comparison(expr);
 696         if (res == 1)
 697                 return rl_one();
 698         if (res == 2)
 699                 return rl_zero();
 700
 701         return alloc_rl(zero, one);
 702 }
 703
 704 static struct range_list *handle_logical_rl(struct expression *expr, int implied, int *recurse_cnt)
 705 {
 706         sval_t left, right;
 707         int left_known = 0;
 708         int right_known = 0;
 709
 710         if (implied == RL_EXACT) {
 711                 if (get_value(expr->left, &left))
 712                         left_known = 1;
 713                 if (get_value(expr->right, &right))
 714                         right_known = 1;
 715         } else {
 716                 if (get_implied_value_internal(expr->left, &left, recurse_cnt))
 717                         left_known = 1;
 718                 if (get_implied_value_internal(expr->right, &right, recurse_cnt))
 719                         right_known = 1;
 720         }
 721
 722         switch (expr->op) {
 723         case SPECIAL_LOGICAL_OR:
 724                 if (left_known && left.value)
 725                         return rl_one();
 726                 if (right_known && right.value)
 727                         return rl_one();
 728                 if (left_known && right_known)
 729                         return rl_zero();
 730                 break;
 731         case SPECIAL_LOGICAL_AND:
 732                 if (left_known && right_known) {
 733                         if (left.value && right.value)
 734                                 return rl_one();
 735                         return rl_zero();
 736                 }
 737                 break;
 738         default:
 739                 return NULL;
 740         }
 741
 742         if (implied == RL_EXACT)
 743                 return NULL;
 744
 745         return alloc_rl(zero, one);
 746 }
 747
 748 static struct range_list *handle_conditional_rl(struct expression *expr, int implied, int *recurse_cnt)
 749 {
 750         struct range_list *true_rl, *false_rl;
 751         struct symbol *type;
 752         int final_pass_orig = final_pass;
 753
 754         if (known_condition_true(expr->conditional))
 755                 return _get_rl(expr->cond_true, implied, recurse_cnt);
 756         if (known_condition_false(expr->conditional))
 757                 return _get_rl(expr->cond_false, implied, recurse_cnt);
 758
 759         if (implied == RL_EXACT)
 760                 return NULL;
 761
 762         if (implied_condition_true(expr->conditional))
 763                 return _get_rl(expr->cond_true, implied, recurse_cnt);
 764         if (implied_condition_false(expr->conditional))
 765                 return _get_rl(expr->cond_false, implied, recurse_cnt);
 766
 767
 768         /* this becomes a problem with deeply nested conditional statements */
 769         if (low_on_memory())
 770                 return NULL;
 771
 772         type = get_type(expr);
 773
 774         __push_fake_cur_stree();
 775         final_pass = 0;
 776         __split_whole_condition(expr->conditional);
 777         true_rl = _get_rl(expr->cond_true, implied, recurse_cnt);
 778         __push_true_states();
 779         __use_false_states();
 780         false_rl = _get_rl(expr->cond_false, implied, recurse_cnt);
 781         __merge_true_states();
 782         __free_fake_cur_stree();
 783         final_pass = final_pass_orig;
 784
 785         if (!true_rl || !false_rl)
 786                 return NULL;
 787         true_rl = cast_rl(type, true_rl);
 788         false_rl = cast_rl(type, false_rl);
 789
 790         return rl_union(true_rl, false_rl);
 791 }
 792
 793 static int get_fuzzy_max_helper(struct expression *expr, sval_t *max)
 794 {
 795         struct smatch_state *state;
 796         sval_t sval;
 797
 798         if (get_hard_max(expr, &sval)) {
 799                 *max = sval;
 800                 return 1;
 801         }
 802
 803         state = get_extra_state(expr);
 804         if (!state || !estate_has_fuzzy_max(state))
 805                 return 0;
 806         *max = sval_cast(get_type(expr), estate_get_fuzzy_max(state));
 807         return 1;
 808 }
 809
 810 static int get_fuzzy_min_helper(struct expression *expr, sval_t *min)
 811 {
 812         struct smatch_state *state;
 813         sval_t sval;
 814
 815         state = get_extra_state(expr);
 816         if (!state || !estate_rl(state))
 817                 return 0;
 818
 819         sval = estate_min(state);
 820         if (sval_is_negative(sval) && sval_is_min(sval))
 821                 return 0;
 822
 823         if (sval_is_max(sval))
 824                 return 0;
 825
 826         *min = sval_cast(get_type(expr), sval);
 827         return 1;
 828 }
 829
 830 int get_const_value(struct expression *expr, sval_t *sval)
 831 {
 832         struct symbol *sym;
 833         sval_t right;
 834
 835         if (expr->type != EXPR_SYMBOL || !expr->symbol)
 836                 return 0;
 837         sym = expr->symbol;
 838         if (!(sym->ctype.modifiers & MOD_CONST))
 839                 return 0;
 840         if (get_value(sym->initializer, &right)) {
 841                 *sval = sval_cast(get_type(expr), right);
 842                 return 1;
 843         }
 844         return 0;
 845 }
 846
 847 struct range_list *var_to_absolute_rl(struct expression *expr)
 848 {
 849         struct smatch_state *state;
 850         struct range_list *rl;
 851
 852         state = get_extra_state(expr);
 853         if (!state || is_whole_rl(estate_rl(state))) {
 854                 state = get_real_absolute_state(expr);
 855                 if (state && state->data && !estate_is_whole(state))
 856                         return clone_rl(estate_rl(state));
 857                 if (get_local_rl(expr, &rl) && !is_whole_rl(rl))
 858                         return rl;
 859                 if (get_mtag_rl(expr, &rl))
 860                         return rl;
 861                 if (get_db_type_rl(expr, &rl) && !is_whole_rl(rl))
 862                         return rl;
 863                 return alloc_whole_rl(get_type(expr));
 864         }
 865         /* err on the side of saying things are possible */
 866         if (!estate_rl(state))
 867                 return alloc_whole_rl(get_type(expr));
 868         return clone_rl(estate_rl(state));
 869 }
 870
 871 static struct range_list *handle_variable(struct expression *expr, int implied, int *recurse_cnt)
 872 {
 873         struct smatch_state *state;
 874         struct range_list *rl;
 875         sval_t sval, min, max;
 876         struct symbol *type;
 877
 878         if (get_const_value(expr, &sval))
 879                 return alloc_rl(sval, sval);
 880
 881         if (custom_handle_variable) {
 882                 rl = custom_handle_variable(expr);
 883                 if (!rl)
 884                         return var_to_absolute_rl(expr);
 885                 return rl;
 886         }
 887
 888         if (implied == RL_EXACT)
 889                 return NULL;
 890
 891         if (get_mtag_sval(expr, &sval))
 892                 return alloc_rl(sval, sval);
 893
 894         type = get_type(expr);
 895         if (type && type->type == SYM_FN)
 896                 return alloc_rl(fn_ptr_min, fn_ptr_max);
 897
 898         switch (implied) {
 899         case RL_HARD:
 900         case RL_IMPLIED:
 901         case RL_ABSOLUTE:
 902                 state = get_extra_state(expr);
 903                 if (!state || !state->data) {
 904                         if (implied == RL_HARD)
 905                                 return NULL;
 906                         if (get_local_rl(expr, &rl))
 907                                 return rl;
 908                         if (get_mtag_rl(expr, &rl))
 909                                 return rl;
 910                         if (get_db_type_rl(expr, &rl))
 911                                 return rl;
 912                         if (is_array(expr) && get_array_rl(expr, &rl))
 913                                 return rl;
 914                         return NULL;
 915                 }
 916                 if (implied == RL_HARD && !estate_has_hard_max(state))
 917                         return NULL;
 918                 return clone_rl(estate_rl(state));
 919         case RL_REAL_ABSOLUTE: {
 920                 struct smatch_state *abs_state;
 921
 922                 state = get_extra_state(expr);
 923                 abs_state = get_real_absolute_state(expr);
 924
 925                 if (estate_rl(state) && estate_rl(abs_state)) {
 926                         return clone_rl(rl_intersection(estate_rl(state),
 927                                                         estate_rl(abs_state)));
 928                 } else if (estate_rl(state)) {
 929                         return clone_rl(estate_rl(state));
 930                 } else if (estate_is_empty(state)) {
 931                         /*
 932                          * FIXME: we don't handle empty extra states correctly.
 933                          *
 934                          * The real abs rl is supposed to be filtered by the
 935                          * extra state if there is one.  We don't bother keeping
 936                          * the abs state in sync all the time because we know it
 937                          * will be filtered later.
 938                          *
 939                          * It's not totally obvious to me how they should be
 940                          * handled.  Perhaps we should take the whole rl and
 941                          * filter by the imaginary states.  Perhaps we should
 942                          * just go with the empty state.
 943                          *
 944                          * Anyway what we currently do is return NULL here and
 945                          * that gets translated into the whole range in
 946                          * get_real_absolute_rl().
 947                          *
 948                          */
 949                         return NULL;
 950                 } else if (estate_rl(abs_state)) {
 951                         return clone_rl(estate_rl(abs_state));
 952                 }
 953
 954                 if (get_local_rl(expr, &rl))
 955                         return rl;
 956                 if (get_mtag_rl(expr, &rl))
 957                         return rl;
 958                 if (get_db_type_rl(expr, &rl))
 959                         return rl;
 960                 if (is_array(expr) && get_array_rl(expr, &rl))
 961                         return rl;
 962                 return NULL;
 963         }
 964         case RL_FUZZY:
 965                 if (!get_fuzzy_min_helper(expr, &min))
 966                         min = sval_type_min(get_type(expr));
 967                 if (!get_fuzzy_max_helper(expr, &max))
 968                         return NULL;
 969                 /* fuzzy ranges are often inverted */
 970                 if (sval_cmp(min, max) > 0) {
 971                         sval = min;
 972                         min = max;
 973                         max = sval;
 974                 }
 975                 return alloc_rl(min, max);
 976         }
 977         return NULL;
 978 }
 979
 980 static sval_t handle_sizeof(struct expression *expr)
 981 {
 982         struct symbol *sym;
 983         sval_t ret;
 984
 985         ret = sval_blank(expr);
 986         sym = expr->cast_type;
 987         if (!sym) {
 988                 sym = evaluate_expression(expr->cast_expression);
 989                 if (!sym) {
 990                         __silence_warnings_for_stmt = true;
 991                         sym = &int_ctype;
 992                 }
 993 #if 0
 994                 /*
 995                  * Expressions of restricted types will possibly get
 996                  * promoted - check that here.  I'm not sure how this works,
 997                  * the problem is that sizeof(le16) shouldn't be promoted and
 998                  * the original code did that...  Let's if zero this out and
 999                  * see what breaks.
1000                  */
1001
1002                 if (is_restricted_type(sym)) {
1003                         if (type_bits(sym) < bits_in_int)
1004                                 sym = &int_ctype;
1005                 }
1006 #endif
1007                 if (is_fouled_type(sym))
1008                         sym = &int_ctype;
1009         }
1010         examine_symbol_type(sym);
1011
1012         ret.type = size_t_ctype;
1013         if (type_bits(sym) <= 0) /* sizeof(void) */ {
1014                 if (get_real_base_type(sym) == &void_ctype)
1015                         ret.value = 1;
1016                 else
1017                         ret.value = 0;
1018         } else
1019                 ret.value = type_bytes(sym);
1020
1021         return ret;
1022 }
1023
1024 static struct range_list *handle_strlen(struct expression *expr, int implied, int *recurse_cnt)
1025 {
1026         struct range_list *rl;
1027         struct expression *arg, *tmp;
1028         sval_t tag;
1029         sval_t ret = { .type = &ulong_ctype };
1030
1031         if (implied == RL_EXACT)
1032                 return NULL;
1033
1034         arg = get_argument_from_call_expr(expr->args, 0);
1035         if (!arg)
1036                 return NULL;
1037         if (arg->type == EXPR_STRING) {
1038                 ret.value = arg->string->length - 1;
1039                 return alloc_rl(ret, ret);
1040         }
1041         if (get_implied_value(arg, &tag) &&
1042             (tmp = fake_string_from_mtag(tag.uvalue))) {
1043                 ret.value = tmp->string->length - 1;
1044                 return alloc_rl(ret, ret);
1045         }
1046
1047         if (implied == RL_HARD || implied == RL_FUZZY)
1048                 return NULL;
1049
1050         if (get_implied_return(expr, &rl))
1051                 return rl;
1052
1053         return NULL;
1054 }
1055
1056 static struct range_list *handle_builtin_constant_p(struct expression *expr, int implied, int *recurse_cnt)
1057 {
1058         struct expression *arg;
1059         struct range_list *rl;
1060         sval_t sval;
1061
1062         arg = get_argument_from_call_expr(expr->args, 0);
1063         rl = _get_rl(arg, RL_EXACT, recurse_cnt);
1064         if (rl_to_sval(rl, &sval))
1065                 return rl_one();
1066         return rl_zero();
1067 }
1068
1069 static struct range_list *handle__builtin_choose_expr(struct expression *expr, int implied, int *recurse_cnt)
1070 {
1071         struct expression *const_expr, *expr1, *expr2;
1072         sval_t sval;
1073
1074         const_expr = get_argument_from_call_expr(expr->args, 0);
1075         expr1 = get_argument_from_call_expr(expr->args, 1);
1076         expr2 = get_argument_from_call_expr(expr->args, 2);
1077
1078         if (!get_value(const_expr, &sval) || !expr1 || !expr2)
1079                 return NULL;
1080         if (sval.value)
1081                 return _get_rl(expr1, implied, recurse_cnt);
1082         return _get_rl(expr2, implied, recurse_cnt);
1083 }
1084
1085 static struct range_list *handle_call_rl(struct expression *expr, int implied, int *recurse_cnt)
1086 {
1087         struct range_list *rl;
1088
1089         if (sym_name_is("__builtin_constant_p", expr->fn))
1090                 return handle_builtin_constant_p(expr, implied, recurse_cnt);
1091
1092         if (sym_name_is("__builtin_choose_expr", expr->fn))
1093                 return handle__builtin_choose_expr(expr, implied, recurse_cnt);
1094
1095         if (sym_name_is("__builtin_expect", expr->fn) ||
1096             sym_name_is("__builtin_bswap16", expr->fn) ||
1097             sym_name_is("__builtin_bswap32", expr->fn) ||
1098             sym_name_is("__builtin_bswap64", expr->fn)) {
1099                 struct expression *arg;
1100
1101                 arg = get_argument_from_call_expr(expr->args, 0);
1102                 return _get_rl(arg, implied, recurse_cnt);
1103         }
1104
1105         if (sym_name_is("strlen", expr->fn))
1106                 return handle_strlen(expr, implied, recurse_cnt);
1107
1108         if (implied == RL_EXACT || implied == RL_HARD || implied == RL_FUZZY)
1109                 return NULL;
1110
1111         if (custom_handle_variable) {
1112                 rl = custom_handle_variable(expr);
1113                 if (rl)
1114                         return rl;
1115         }
1116
1117         if (get_implied_return(expr, &rl))
1118                 return rl;
1119         return db_return_vals(expr);
1120 }
1121
1122 static struct range_list *handle_cast(struct expression *expr, int implied, int *recurse_cnt)
1123 {
1124         struct range_list *rl;
1125         struct symbol *type;
1126
1127         type = get_type(expr);
1128         rl = _get_rl(expr->cast_expression, implied, recurse_cnt);
1129         if (rl)
1130                 return cast_rl(type, rl);
1131         if (implied == RL_ABSOLUTE || implied == RL_REAL_ABSOLUTE)
1132                 return alloc_whole_rl(type);
1133         if (implied == RL_IMPLIED && type &&
1134             type_bits(type) > 0 && type_bits(type) < 32)
1135                 return alloc_whole_rl(type);
1136         return NULL;
1137 }
1138
1139 static struct range_list *_get_rl(struct expression *expr, int implied, int *recurse_cnt)
1140 {
1141         struct range_list *rl;
1142         struct symbol *type;
1143         sval_t sval;
1144
1145         type = get_type(expr);
1146         expr = strip_parens(expr);
1147         if (!expr)
1148                 return NULL;
1149
1150         if (++(*recurse_cnt) >= 200)
1151                 return NULL;
1152
1153         switch(expr->type) {
1154         case EXPR_CAST:
1155         case EXPR_FORCE_CAST:
1156         case EXPR_IMPLIED_CAST:
1157                 rl = handle_cast(expr, implied, recurse_cnt);
1158                 goto out_cast;
1159         }
1160
1161         expr = strip_expr(expr);
1162         if (!expr)
1163                 return NULL;
1164
1165         switch (expr->type) {
1166         case EXPR_VALUE:
1167                 sval = sval_from_val(expr, expr->value);
1168                 rl = alloc_rl(sval, sval);
1169                 break;
1170         case EXPR_PREOP:
1171                 rl = handle_preop_rl(expr, implied, recurse_cnt);
1172                 break;
1173         case EXPR_POSTOP:
1174                 rl = _get_rl(expr->unop, implied, recurse_cnt);
1175                 break;
1176         case EXPR_BINOP:
1177                 rl = handle_binop_rl(expr, implied, recurse_cnt);
1178                 break;
1179         case EXPR_COMPARE:
1180                 rl = handle_comparison_rl(expr, implied, recurse_cnt);
1181                 break;
1182         case EXPR_LOGICAL:
1183                 rl = handle_logical_rl(expr, implied, recurse_cnt);
1184                 break;
1185         case EXPR_PTRSIZEOF:
1186         case EXPR_SIZEOF:
1187                 sval = handle_sizeof(expr);
1188                 rl = alloc_rl(sval, sval);
1189                 break;
1190         case EXPR_SELECT:
1191         case EXPR_CONDITIONAL:
1192                 rl = handle_conditional_rl(expr, implied, recurse_cnt);
1193                 break;
1194         case EXPR_CALL:
1195                 rl = handle_call_rl(expr, implied, recurse_cnt);
1196                 break;
1197         case EXPR_STRING:
1198                 rl = NULL;
1199                 if (get_mtag_sval(expr, &sval))
1200                         rl = alloc_rl(sval, sval);
1201                 break;
1202         default:
1203                 rl = handle_variable(expr, implied, recurse_cnt);
1204         }
1205
1206 out_cast:
1207         if (rl)
1208                 return rl;
1209         if (type && (implied == RL_ABSOLUTE || implied == RL_REAL_ABSOLUTE))
1210                 return alloc_whole_rl(type);
1211         return NULL;
1212 }
1213
1214 struct {
1215         struct expression *expr;
1216         struct range_list *rl;
1217 } cached_results[24];
1218 static int cache_idx;
1219
1220 void clear_math_cache(void)
1221 {
1222         memset(cached_results, 0, sizeof(cached_results));
1223 }
1224
1225 /* returns 1 if it can get a value literal or else returns 0 */
1226 int get_value(struct expression *expr, sval_t *sval)
1227 {
1228         struct range_list *(*orig_custom_fn)(struct expression *expr);
1229         struct range_list *rl;
1230         int recurse_cnt = 0;
1231         sval_t tmp;
1232         int i;
1233
1234         /*
1235          * This only handles RL_EXACT because other expr statements can be
1236          * different at different points.  Like the list iterator, for example.
1237          */
1238         for (i = 0; i < ARRAY_SIZE(cached_results); i++) {
1239                 if (expr == cached_results[i].expr)
1240                         return rl_to_sval(cached_results[i].rl, sval);
1241         }
1242
1243         orig_custom_fn = custom_handle_variable;
1244         custom_handle_variable = NULL;
1245         rl = _get_rl(expr, RL_EXACT, &recurse_cnt);
1246         if (!rl_to_sval(rl, &tmp))
1247                 rl = NULL;
1248         custom_handle_variable = orig_custom_fn;
1249
1250         cached_results[cache_idx].expr = expr;
1251         cached_results[cache_idx].rl = rl;
1252         cache_idx = (cache_idx + 1) % ARRAY_SIZE(cached_results);
1253
1254         if (!rl)
1255                 return 0;
1256
1257         *sval = tmp;
1258         return 1;
1259 }
1260
1261 static int get_implied_value_internal(struct expression *expr, sval_t *sval, int *recurse_cnt)
1262 {
1263         struct range_list *rl;
1264
1265         rl =  _get_rl(expr, RL_IMPLIED, recurse_cnt);
1266         if (!rl_to_sval(rl, sval))
1267                 return 0;
1268         return 1;
1269 }
1270
1271 int get_implied_value(struct expression *expr, sval_t *sval)
1272 {
1273         struct range_list *rl;
1274         int recurse_cnt = 0;
1275
1276         rl =  _get_rl(expr, RL_IMPLIED, &recurse_cnt);
1277         if (!rl_to_sval(rl, sval))
1278                 return 0;
1279         return 1;
1280 }
1281
1282 int get_implied_min(struct expression *expr, sval_t *sval)
1283 {
1284         struct range_list *rl;
1285         int recurse_cnt = 0;
1286
1287         rl =  _get_rl(expr, RL_IMPLIED, &recurse_cnt);
1288         if (!rl)
1289                 return 0;
1290         *sval = rl_min(rl);
1291         return 1;
1292 }
1293
1294 int get_implied_max(struct expression *expr, sval_t *sval)
1295 {
1296         struct range_list *rl;
1297         int recurse_cnt = 0;
1298
1299         rl =  _get_rl(expr, RL_IMPLIED, &recurse_cnt);
1300         if (!rl)
1301                 return 0;
1302         *sval = rl_max(rl);
1303         return 1;
1304 }
1305
1306 int get_implied_rl(struct expression *expr, struct range_list **rl)
1307 {
1308         int recurse_cnt = 0;
1309
1310         *rl = _get_rl(expr, RL_IMPLIED, &recurse_cnt);
1311         if (*rl)
1312                 return 1;
1313         return 0;
1314 }
1315
1316 static int get_absolute_rl_internal(struct expression *expr, struct range_list **rl, int *recurse_cnt)
1317 {
1318         *rl = _get_rl(expr, RL_ABSOLUTE, recurse_cnt);
1319         if (!*rl)
1320                 *rl = alloc_whole_rl(get_type(expr));
1321         return 1;
1322 }
1323
1324 int get_absolute_rl(struct expression *expr, struct range_list **rl)
1325 {
1326         int recurse_cnt = 0;
1327
1328         *rl = _get_rl(expr, RL_ABSOLUTE, &recurse_cnt);
1329         if (!*rl)
1330                 *rl = alloc_whole_rl(get_type(expr));
1331         return 1;
1332 }
1333
1334 int get_real_absolute_rl(struct expression *expr, struct range_list **rl)
1335 {
1336         int recurse_cnt = 0;
1337
1338         *rl = _get_rl(expr, RL_REAL_ABSOLUTE, &recurse_cnt);
1339         if (!*rl)
1340                 *rl = alloc_whole_rl(get_type(expr));
1341         return 1;
1342 }
1343
1344 int custom_get_absolute_rl(struct expression *expr,
1345                            struct range_list *(*fn)(struct expression *expr),
1346                            struct range_list **rl)
1347 {
1348         int recurse_cnt = 0;
1349
1350         *rl = NULL;
1351         custom_handle_variable = fn;
1352         *rl = _get_rl(expr, RL_REAL_ABSOLUTE, &recurse_cnt);
1353         custom_handle_variable = NULL;
1354         return 1;
1355 }
1356
1357 int get_implied_rl_var_sym(const char *var, struct symbol *sym, struct range_list **rl)
1358 {
1359         struct smatch_state *state;
1360
1361         state = get_state(SMATCH_EXTRA, var, sym);
1362         *rl = estate_rl(state);
1363         if (*rl)
1364                 return 1;
1365         return 0;
1366 }
1367
1368 int get_hard_max(struct expression *expr, sval_t *sval)
1369 {
1370         struct range_list *rl;
1371         int recurse_cnt = 0;
1372
1373         rl =  _get_rl(expr, RL_HARD, &recurse_cnt);
1374         if (!rl)
1375                 return 0;
1376         *sval = rl_max(rl);
1377         return 1;
1378 }
1379
1380 int get_fuzzy_min(struct expression *expr, sval_t *sval)
1381 {
1382         struct range_list *rl;
1383         sval_t tmp;
1384         int recurse_cnt = 0;
1385
1386         rl =  _get_rl(expr, RL_FUZZY, &recurse_cnt);
1387         if (!rl)
1388                 return 0;
1389         tmp = rl_min(rl);
1390         if (sval_is_negative(tmp) && sval_is_min(tmp))
1391                 return 0;
1392         *sval = tmp;
1393         return 1;
1394 }
1395
1396 int get_fuzzy_max(struct expression *expr, sval_t *sval)
1397 {
1398         struct range_list *rl;
1399         sval_t max;
1400         int recurse_cnt = 0;
1401
1402         rl =  _get_rl(expr, RL_FUZZY, &recurse_cnt);
1403         if (!rl)
1404                 return 0;
1405         max = rl_max(rl);
1406         if (max.uvalue > INT_MAX - 10000)
1407                 return 0;
1408         *sval = max;
1409         return 1;
1410 }
1411
1412 int get_absolute_min(struct expression *expr, sval_t *sval)
1413 {
1414         struct range_list *rl;
1415         struct symbol *type;
1416         int recurse_cnt = 0;
1417
1418         type = get_type(expr);
1419         if (!type)
1420                 type = &llong_ctype;  // FIXME: this is wrong but places assume get type can't fail.
1421         rl = _get_rl(expr, RL_REAL_ABSOLUTE, &recurse_cnt);
1422         if (rl)
1423                 *sval = rl_min(rl);
1424         else
1425                 *sval = sval_type_min(type);
1426
1427         if (sval_cmp(*sval, sval_type_min(type)) < 0)
1428                 *sval = sval_type_min(type);
1429         return 1;
1430 }
1431
1432 int get_absolute_max(struct expression *expr, sval_t *sval)
1433 {
1434         struct range_list *rl;
1435         struct symbol *type;
1436         int recurse_cnt = 0;
1437
1438         type = get_type(expr);
1439         if (!type)
1440                 type = &llong_ctype;
1441         rl = _get_rl(expr, RL_REAL_ABSOLUTE, &recurse_cnt);
1442         if (rl)
1443                 *sval = rl_max(rl);
1444         else
1445                 *sval = sval_type_max(type);
1446
1447         if (sval_cmp(sval_type_max(type), *sval) < 0)
1448                 *sval = sval_type_max(type);
1449         return 1;
1450 }
1451
1452 int known_condition_true(struct expression *expr)
1453 {
1454         sval_t tmp;
1455
1456         if (!expr)
1457                 return 0;
1458
1459         if (get_value(expr, &tmp) && tmp.value)
1460                 return 1;
1461
1462         return 0;
1463 }
1464
1465 int known_condition_false(struct expression *expr)
1466 {
1467         if (!expr)
1468                 return 0;
1469
1470         if (is_zero(expr))
1471                 return 1;
1472
1473         return 0;
1474 }
1475
1476 int implied_condition_true(struct expression *expr)
1477 {
1478         sval_t tmp;
1479
1480         if (!expr)
1481                 return 0;
1482
1483         if (known_condition_true(expr))
1484                 return 1;
1485         if (get_implied_value(expr, &tmp) && tmp.value)
1486                 return 1;
1487
1488         if (expr->type == EXPR_POSTOP)
1489                 return implied_condition_true(expr->unop);
1490
1491         if (expr->type == EXPR_PREOP && expr->op == SPECIAL_DECREMENT)
1492                 return implied_not_equal(expr->unop, 1);
1493         if (expr->type == EXPR_PREOP && expr->op == SPECIAL_INCREMENT)
1494                 return implied_not_equal(expr->unop, -1);
1495
1496         expr = strip_expr(expr);
1497         switch (expr->type) {
1498         case EXPR_COMPARE:
1499                 if (do_comparison(expr) == 1)
1500                         return 1;
1501                 break;
1502         case EXPR_PREOP:
1503                 if (expr->op == '!') {
1504                         if (implied_condition_false(expr->unop))
1505                                 return 1;
1506                         break;
1507                 }
1508                 break;
1509         default:
1510                 if (implied_not_equal(expr, 0) == 1)
1511                         return 1;
1512                 break;
1513         }
1514         return 0;
1515 }
1516
1517 int implied_condition_false(struct expression *expr)
1518 {
1519         struct expression *tmp;
1520         sval_t sval;
1521
1522         if (!expr)
1523                 return 0;
1524
1525         if (known_condition_false(expr))
1526                 return 1;
1527
1528         switch (expr->type) {
1529         case EXPR_COMPARE:
1530                 if (do_comparison(expr) == 2)
1531                         return 1;
1532         case EXPR_PREOP:
1533                 if (expr->op == '!') {
1534                         if (implied_condition_true(expr->unop))
1535                                 return 1;
1536                         break;
1537                 }
1538                 tmp = strip_expr(expr);
1539                 if (tmp != expr)
1540                         return implied_condition_false(tmp);
1541                 break;
1542         default:
1543                 if (get_implied_value(expr, &sval) && sval.value == 0)
1544                         return 1;
1545                 break;
1546         }
1547         return 0;
1548 }
1549
1550 int can_integer_overflow(struct symbol *type, struct expression *expr)
1551 {
1552         int op;
1553         sval_t lmax, rmax, res;
1554
1555         if (!type)
1556                 type = &int_ctype;
1557
1558         expr = strip_expr(expr);
1559
1560         if (expr->type == EXPR_ASSIGNMENT) {
1561                 switch(expr->op) {
1562                 case SPECIAL_MUL_ASSIGN:
1563                         op = '*';
1564                         break;
1565                 case SPECIAL_ADD_ASSIGN:
1566                         op = '+';
1567                         break;
1568                 case SPECIAL_SHL_ASSIGN:
1569                         op = SPECIAL_LEFTSHIFT;
1570                         break;
1571                 default:
1572                         return 0;
1573                 }
1574         } else if (expr->type == EXPR_BINOP) {
1575                 if (expr->op != '*' && expr->op != '+' && expr->op != SPECIAL_LEFTSHIFT)
1576                         return 0;
1577                 op = expr->op;
1578         } else {
1579                 return 0;
1580         }
1581
1582         get_absolute_max(expr->left, &lmax);
1583         get_absolute_max(expr->right, &rmax);
1584
1585         if (sval_binop_overflows(lmax, op, rmax))
1586                 return 1;
1587
1588         res = sval_binop(lmax, op, rmax);
1589         if (sval_cmp(res, sval_type_max(type)) > 0)
1590                 return 1;
1591         return 0;
1592 }