?  search:
summary | log | graphiclog1 | graphiclog2 | commit | commitdiff | tree | refs | edit | fork
blame | history | raw | HEAD
math: store all constant EXPR_BINOP results
[smatch.git] / smatch_math.c
blob47bb99c29336415212e373271a8f1d714b56bd53
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 #define _GNU_SOURCE
19 #include <string.h>
20
21 #include "symbol.h"
22 #include "smatch.h"
23 #include "smatch_slist.h"
24 #include "smatch_extra.h"
25
26 static bool get_rl_sval(struct expression *expr, int implied, int *recurse_cnt, struct range_list **res, sval_t *sval_res);
27 static bool get_rl_internal(struct expression *expr, int implied, int *recurse_cnt, struct range_list **res);
28 static bool handle_variable(struct expression *expr, int implied, int *recurse_cnt, struct range_list **res, sval_t *res_sval);
29 static struct range_list *(*custom_handle_variable)(struct expression *expr);
30
31 static bool get_implied_value_internal(struct expression *expr, int *recurse_cnt, sval_t *res_sval);
32 static int get_absolute_rl_internal(struct expression *expr, struct range_list **rl, int *recurse_cnt);
33
34 static sval_t zero = {.type = &int_ctype, {.value = 0} };
35 static sval_t one = {.type = &int_ctype, {.value = 1} };
36
37 static int fast_math_only;
38
39 struct range_list *rl_zero(void)
40 {
41 static struct range_list *zero_perm;
42
43 if (!zero_perm)
44 zero_perm = clone_rl_permanent(alloc_rl(zero, zero));
45 return zero_perm;
46 }
47
48 struct range_list *rl_one(void)
49 {
50 static struct range_list *one_perm;
51
52 if (!one_perm)
53 one_perm = clone_rl_permanent(alloc_rl(one, one));
54
55 return one_perm;
56 }
57
58 enum {
59 RL_EXACT,
60 RL_HARD,
61 RL_FUZZY,
62 RL_IMPLIED,
63 RL_ABSOLUTE,
64 RL_REAL_ABSOLUTE,
65 };
66
67 static bool last_stmt_rl(struct statement *stmt, int implied, int *recurse_cnt, struct range_list **res, sval_t *res_sval)
68 {
69 struct expression *expr;
70
71 if (!stmt)
72 return false;
73
74 stmt = last_ptr_list((struct ptr_list *)stmt->stmts);
75 if (stmt->type == STMT_LABEL) {
76 if (stmt->label_statement &&
77 stmt->label_statement->type == STMT_EXPRESSION)
78 expr = stmt->label_statement->expression;
79 else
80 return false;
81 } else if (stmt->type == STMT_EXPRESSION) {
82 expr = stmt->expression;
83 } else {
84 return false;
85 }
86 return get_rl_sval(expr, implied, recurse_cnt, res, res_sval);
87 }
88
89 static bool handle_expression_statement_rl(struct expression *expr, int implied,
90 int *recurse_cnt, struct range_list **res, sval_t *res_sval)
91 {
92 return last_stmt_rl(get_expression_statement(expr), implied, recurse_cnt, res, res_sval);
93 }
94
95 static bool handle_address(struct expression *expr, int implied, int *recurse_cnt, struct range_list **res, sval_t *res_sval)
96 {
97 struct range_list *rl;
98 static int recursed;
99 sval_t sval;
100
101 if (recursed > 10)
102 return false;
103 if (implied == RL_EXACT)
104 return false;
105
106 if (custom_handle_variable) {
107 rl = custom_handle_variable(expr);
108 if (rl) {
109 *res = rl;
110 return true;
111 }
112 }
113
114 recursed++;
115 if (get_mtag_sval(expr, &sval)) {
116 recursed--;
117 *res_sval = sval;
118 return true;
119 }
120
121 if (get_address_rl(expr, res)) {
122 recursed--;
123 return true;
124 }
125 recursed--;
126 return 0;
127 }
128
129 static bool handle_ampersand_rl(struct expression *expr, int implied, int *recurse_cnt, struct range_list **res, sval_t *res_sval)
130 {
131 return handle_address(expr, implied, recurse_cnt, res, res_sval);
132 }
133
134 static bool handle_negate_rl(struct expression *expr, int implied, int *recurse_cnt, struct range_list **res, sval_t *res_sval)
135 {
136 if (known_condition_true(expr->unop)) {
137 *res_sval = zero;
138 return true;
139 }
140 if (known_condition_false(expr->unop)) {
141 *res_sval = one;
142 return true;
143 }
144
145 if (implied == RL_EXACT)
146 return false;
147
148 if (implied_condition_true(expr->unop)) {
149 *res_sval = zero;
150 return true;
151 }
152 if (implied_condition_false(expr->unop)) {
153 *res_sval = one;
154 return true;
155 }
156
157 *res = alloc_rl(zero, one);
158 return true;
159 }
160
161 static bool handle_bitwise_negate(struct expression *expr, int implied, int *recurse_cnt, sval_t *res_sval)
162 {
163 struct range_list *rl;
164 sval_t sval = {};
165
166 if (!get_rl_sval(expr->unop, implied, recurse_cnt, &rl, &sval))
167 return false;
168 if (!sval.type && !rl_to_sval(rl, &sval))
169 return false;
170 sval = sval_preop(sval, '~');
171 sval_cast(get_type(expr->unop), sval);
172 *res_sval = sval;
173 return true;
174 }
175
176 static bool untrusted_type_min(struct expression *expr)
177 {
178 struct range_list *rl;
179
180 rl = var_user_rl(expr);
181 return rl && sval_is_min(rl_min(rl));
182 }
183
184 static bool handle_minus_preop(struct expression *expr, int implied, int *recurse_cnt, struct range_list **res, sval_t *res_sval)
185 {
186 struct range_list *rl;
187 struct range_list *ret = NULL;
188 struct symbol *type;
189 sval_t neg_one = { .value = -1 };
190 sval_t zero = { .value = 0 };
191 sval_t sval = {};
192
193 if (!get_rl_sval(expr->unop, implied, recurse_cnt, &rl, &sval))
194 return false;
195 if (sval.type) {
196 *res_sval = sval_preop(sval, '-');
197 return true;
198 }
199 /*
200 * One complication is that -INT_MIN is still INT_MIN because of integer
201 * overflows... But how many times do we set a time out to INT_MIN?
202 * So normally when we call abs() then it does return a positive value.
203 *
204 */
205 type = rl_type(rl);
206 neg_one.type = zero.type = type;
207
208 if (sval_is_negative(rl_min(rl))) {
209 struct range_list *neg;
210 struct data_range *drange;
211 sval_t new_min, new_max;
212
213 neg = alloc_rl(sval_type_min(type), neg_one);
214 neg = rl_intersection(rl, neg);
215
216 if (sval_is_min(rl_min(neg)) && !sval_is_min(rl_max(neg)))
217 neg = remove_range(neg, sval_type_min(type), sval_type_min(type));
218
219 FOR_EACH_PTR(neg, drange) {
220 new_min = drange->max;
221 new_min.value = -new_min.value;
222 new_max = drange->min;
223 new_max.value = -new_max.value;
224 add_range(&ret, new_min, new_max);
225 } END_FOR_EACH_PTR(drange);
226
227 if (untrusted_type_min(expr))
228 add_range(&ret, sval_type_min(type), sval_type_min(type));
229 }
230
231 if (!sval_is_negative(rl_max(rl))) {
232 struct range_list *pos;
233 struct data_range *drange;
234 sval_t new_min, new_max;
235
236 pos = alloc_rl(zero, sval_type_max(type));
237 pos = rl_intersection(rl, pos);
238
239 FOR_EACH_PTR(pos, drange) {
240 new_min = drange->max;
241 new_min.value = -new_min.value;
242 new_max = drange->min;
243 new_max.value = -new_max.value;
244 add_range(&ret, new_min, new_max);
245 } END_FOR_EACH_PTR(drange);
246 }
247
248 *res = ret;
249 return true;
250 }
251
252 static bool handle_preop_rl(struct expression *expr, int implied, int *recurse_cnt, struct range_list **res, sval_t *res_sval)
253 {
254 switch (expr->op) {
255 case '&':
256 return handle_ampersand_rl(expr, implied, recurse_cnt, res, res_sval);
257 case '!':
258 return handle_negate_rl(expr, implied, recurse_cnt, res, res_sval);
259 case '~':
260 return handle_bitwise_negate(expr, implied, recurse_cnt, res_sval);
261 case '-':
262 return handle_minus_preop(expr, implied, recurse_cnt, res, res_sval);
263 case '*':
264 return handle_variable(expr, implied, recurse_cnt, res, res_sval);
265 case '(':
266 return handle_expression_statement_rl(expr, implied, recurse_cnt, res, res_sval);
267 default:
268 return false;
269 }
270 }
271
272 static bool handle_divide_rl(struct expression *expr, int implied, int *recurse_cnt, struct range_list **res)
273 {
274 struct range_list *left_rl = NULL;
275 struct range_list *right_rl = NULL;
276 struct symbol *type;
277
278 type = get_type(expr);
279
280 get_rl_internal(expr->left, implied, recurse_cnt, &left_rl);
281 left_rl = cast_rl(type, left_rl);
282 get_rl_internal(expr->right, implied, recurse_cnt, &right_rl);
283 right_rl = cast_rl(type, right_rl);
284
285 if (!left_rl || !right_rl)
286 return false;
287
288 if (implied != RL_REAL_ABSOLUTE) {
289 if (is_whole_rl(left_rl) || is_whole_rl(right_rl))
290 return false;
291 }
292
293 *res = rl_binop(left_rl, '/', right_rl);
294 return true;
295 }
296
297 static int handle_offset_subtraction(struct expression *expr)
298 {
299 struct expression *left, *right;
300 struct symbol *left_sym, *right_sym;
301 struct symbol *type;
302 int left_offset, right_offset;
303
304 type = get_type(expr);
305 if (!type || type->type != SYM_PTR)
306 return -1;
307 type = get_real_base_type(type);
308 if (!type || (type_bits(type) != 8 && (type != &void_ctype)))
309 return -1;
310
311 left = strip_expr(expr->left);
312 right = strip_expr(expr->right);
313
314 if (left->type != EXPR_PREOP || left->op != '&')
315 return -1;
316 left = strip_expr(left->unop);
317
318 left_sym = expr_to_sym(left);
319 right_sym = expr_to_sym(right);
320 if (!left_sym || left_sym != right_sym)
321 return -1;
322
323 left_offset = get_member_offset_from_deref(left);
324 if (right->type == EXPR_SYMBOL)
325 right_offset = 0;
326 else {
327 if (right->type != EXPR_PREOP || right->op != '&')
328 return -1;
329 right = strip_expr(right->unop);
330 right_offset = get_member_offset_from_deref(right);
331 }
332 if (left_offset < 0 || right_offset < 0)
333 return -1;
334
335 return left_offset - right_offset;
336 }
337
338 static bool max_is_unknown_max(struct range_list *rl)
339 {
340 /*
341 * The issue with this code is that we had:
342 * if (foo > 1) return 1 - foo;
343 * Ideally we would say that returns s32min-(-1) but what Smatch
344 * was saying was that the lowest possible value was "1 - INT_MAX"
345 *
346 * My solution is to ignore max values for int or larger. I keep
347 * the max for shorts etc, because those might be worthwhile.
348 *
349 * The problem with just returning 1 - INT_MAX is that that is
350 * treated as useful information but s32min is treated as basically
351 * unknown.
352 */
353
354 if (type_bits(rl_type(rl)) < 31)
355 return false;
356 return sval_is_max(rl_max(rl));
357 }
358
359 static bool handle_add_rl(struct expression *expr, int implied, int *recurse_cnt, struct range_list **res)
360 {
361 struct range_list *left_rl = NULL;
362 struct range_list *right_rl = NULL;
363 struct range_list *valid;
364 struct symbol *type;
365 sval_t min, max;
366
367 type = get_type(expr);
368
369 get_rl_internal(expr->left, implied, recurse_cnt, &left_rl);
370 left_rl = cast_rl(type, left_rl);
371 get_rl_internal(expr->right, implied, recurse_cnt, &right_rl);
372 right_rl = cast_rl(type, right_rl);
373
374 if (!left_rl)
375 return false;
376
377 if (type_is_ptr(type) && !var_user_rl(expr->right)) {
378 valid = rl_intersection(left_rl, valid_ptr_rl);
379 if (valid && rl_equiv(valid, left_rl))
380 return valid_ptr_rl;
381 }
382
383 if (!right_rl)
384 return false;
385
386 if (sval_binop_overflows(rl_min(left_rl), expr->op, rl_min(right_rl)))
387 return false;
388 if (sval_binop_overflows(rl_max(left_rl), expr->op, rl_max(right_rl)))
389 return false;
390
391 min = sval_binop(rl_min(left_rl), expr->op, rl_min(right_rl));
392 max = sval_binop(rl_max(left_rl), expr->op, rl_max(right_rl));
393
394 *res = alloc_rl(min, max);
395 return true;
396 }
397
398 static bool handle_subtract_rl(struct expression *expr, int implied, int *recurse_cnt, struct range_list **res)
399 {
400 struct symbol *type;
401 struct range_list *left_orig, *right_orig;
402 struct range_list *left_rl, *right_rl;
403 sval_t min, max, tmp;
404 int comparison;
405 int offset;
406
407 type = get_type(expr);
408
409 offset = handle_offset_subtraction(expr);
410 if (offset >= 0) {
411 tmp.type = type;
412 tmp.value = offset;
413
414 *res = alloc_rl(tmp, tmp);
415 return true;
416 }
417
418 comparison = get_comparison(expr->left, expr->right);
419
420 left_orig = NULL;
421 get_rl_internal(expr->left, implied, recurse_cnt, &left_orig);
422 left_rl = cast_rl(type, left_orig);
423 right_orig = NULL;
424 get_rl_internal(expr->right, implied, recurse_cnt, &right_orig);
425 right_rl = cast_rl(type, right_orig);
426
427 if ((!left_rl || !right_rl) &&
428 (implied == RL_EXACT || implied == RL_HARD || implied == RL_FUZZY))
429 return false;
430
431 if (!left_rl)
432 left_rl = alloc_whole_rl(type);
433 if (!right_rl)
434 right_rl = alloc_whole_rl(type);
435
436 /* negative values complicate everything fix this later */
437 if (sval_is_negative(rl_min(right_rl)))
438 return false;
439 max = rl_max(left_rl);
440 min = sval_type_min(type);
441
442 switch (comparison) {
443 case '>':
444 case SPECIAL_UNSIGNED_GT:
445 min = sval_type_val(type, 1);
446 max = rl_max(left_rl);
447 break;
448 case SPECIAL_GTE:
449 case SPECIAL_UNSIGNED_GTE:
450 min = sval_type_val(type, 0);
451 max = rl_max(left_rl);
452 break;
453 case SPECIAL_EQUAL:
454 min = sval_type_val(type, 0);
455 max = sval_type_val(type, 0);
456 break;
457 case '<':
458 case SPECIAL_UNSIGNED_LT:
459 max = sval_type_val(type, -1);
460 break;
461 case SPECIAL_LTE:
462 case SPECIAL_UNSIGNED_LTE:
463 max = sval_type_val(type, 0);
464 break;
465 default:
466 if (!left_orig || !right_orig)
467 return false;
468 *res = rl_binop(left_rl, '-', right_rl);
469 return true;
470 }
471
472 if (!max_is_unknown_max(right_rl) &&
473 !sval_binop_overflows(rl_min(left_rl), '-', rl_max(right_rl))) {
474 tmp = sval_binop(rl_min(left_rl), '-', rl_max(right_rl));
475 if (sval_cmp(tmp, min) > 0)
476 min = tmp;
477 }
478
479 if (!sval_is_max(rl_max(left_rl))) {
480 tmp = sval_binop(rl_max(left_rl), '-', rl_min(right_rl));
481 if (sval_cmp(tmp, max) < 0)
482 max = tmp;
483 }
484
485 if (sval_is_min(min) && sval_is_max(max))
486 return false;
487
488 *res = cast_rl(type, alloc_rl(min, max));
489 return true;
490 }
491
492 static bool handle_mod_rl(struct expression *expr, int implied, int *recurse_cnt, struct range_list **res)
493 {
494 struct range_list *rl;
495 sval_t left, right, sval;
496
497 if (implied == RL_EXACT) {
498 if (!get_implied_value(expr->right, &right))
499 return false;
500 if (!get_implied_value(expr->left, &left))
501 return false;
502 sval = sval_binop(left, '%', right);
503 *res = alloc_rl(sval, sval);
504 return true;
505 }
506 /* if we can't figure out the right side it's probably hopeless */
507 if (!get_implied_value_internal(expr->right, recurse_cnt, &right))
508 return false;
509
510 right = sval_cast(get_type(expr), right);
511 right.value--;
512
513 if (get_rl_internal(expr->left, implied, recurse_cnt, &rl) && rl &&
514 rl_max(rl).uvalue < right.uvalue)
515 right.uvalue = rl_max(rl).uvalue;
516
517 *res = alloc_rl(sval_cast(right.type, zero), right);
518 return true;
519 }
520
521 static bool handle_bitwise_AND(struct expression *expr, int implied, int *recurse_cnt, struct range_list **res)
522 {
523 struct symbol *type;
524 struct range_list *left_rl, *right_rl;
525 int new_recurse;
526
527 if (implied != RL_IMPLIED && implied != RL_ABSOLUTE && implied != RL_REAL_ABSOLUTE)
528 return false;
529
530 type = get_type(expr);
531
532 if (!get_rl_internal(expr->left, implied, recurse_cnt, &left_rl))
533 left_rl = alloc_whole_rl(type);
534 left_rl = cast_rl(type, left_rl);
535
536 new_recurse = *recurse_cnt;
537 if (*recurse_cnt >= 200)
538 new_recurse = 100; /* Let's try super hard to get the mask */
539 if (!get_rl_internal(expr->right, implied, &new_recurse, &right_rl))
540 right_rl = alloc_whole_rl(type);
541 right_rl = cast_rl(type, right_rl);
542 *recurse_cnt = new_recurse;
543
544 *res = rl_binop(left_rl, '&', right_rl);
545 return true;
546 }
547
548 static bool use_rl_binop(struct expression *expr, int implied, int *recurse_cnt, struct range_list **res)
549 {
550 struct symbol *type;
551 struct range_list *left_rl, *right_rl;
552
553 if (implied != RL_IMPLIED && implied != RL_ABSOLUTE && implied != RL_REAL_ABSOLUTE)
554 return false;
555
556 type = get_type(expr);
557
558 get_absolute_rl_internal(expr->left, &left_rl, recurse_cnt);
559 get_absolute_rl_internal(expr->right, &right_rl, recurse_cnt);
560 left_rl = cast_rl(type, left_rl);
561 right_rl = cast_rl(type, right_rl);
562 if (!left_rl || !right_rl)
563 return false;
564
565 *res = rl_binop(left_rl, expr->op, right_rl);
566 return true;
567 }
568
569 static bool handle_right_shift(struct expression *expr, int implied, int *recurse_cnt, struct range_list **res)
570 {
571 struct range_list *left_rl, *right_rl;
572 sval_t min, max;
573
574 if (implied == RL_EXACT || implied == RL_HARD)
575 return false;
576
577 if (get_rl_internal(expr->left, implied, recurse_cnt, &left_rl)) {
578 max = rl_max(left_rl);
579 min = rl_min(left_rl);
580 } else {
581 if (implied == RL_FUZZY)
582 return false;
583 max = sval_type_max(get_type(expr->left));
584 min = sval_type_val(get_type(expr->left), 0);
585 }
586
587 if (get_rl_internal(expr->right, implied, recurse_cnt, &right_rl) &&
588 !sval_is_negative(rl_min(right_rl))) {
589 min = sval_binop(min, SPECIAL_RIGHTSHIFT, rl_max(right_rl));
590 max = sval_binop(max, SPECIAL_RIGHTSHIFT, rl_min(right_rl));
591 } else if (!sval_is_negative(min)) {
592 min.value = 0;
593 max = sval_type_max(max.type);
594 } else {
595 return false;
596 }
597
598 *res = alloc_rl(min, max);
599 return true;
600 }
601
602 static bool handle_left_shift(struct expression *expr, int implied, int *recurse_cnt, struct range_list **res)
603 {
604 struct range_list *left_rl, *rl;
605 sval_t right;
606
607 if (implied == RL_EXACT || implied == RL_HARD)
608 return false;
609 /* this is hopeless without the right side */
610 if (!get_implied_value_internal(expr->right, recurse_cnt, &right))
611 return false;
612 if (!get_rl_internal(expr->left, implied, recurse_cnt, &left_rl)) {
613 if (implied == RL_FUZZY)
614 return false;
615 left_rl = alloc_whole_rl(get_type(expr->left));
616 }
617
618 rl = rl_binop(left_rl, SPECIAL_LEFTSHIFT, alloc_rl(right, right));
619 if (!rl)
620 return false;
621 *res = rl;
622 return true;
623 }
624
625 static bool handle_known_binop(struct expression *expr, sval_t *res)
626 {
627 sval_t left, right;
628
629 if (!get_value(expr->left, &left))
630 return false;
631 if (!get_value(expr->right, &right))
632 return false;
633 *res = sval_binop(left, expr->op, right);
634 return true;
635 }
636
637 static int has_actual_ranges(struct range_list *rl)
638 {
639 struct data_range *tmp;
640
641 FOR_EACH_PTR(rl, tmp) {
642 if (sval_cmp(tmp->min, tmp->max) != 0)
643 return 1;
644 } END_FOR_EACH_PTR(tmp);
645 return 0;
646 }
647
648 static struct range_list *handle_implied_binop(struct range_list *left_rl, int op, struct range_list *right_rl)
649 {
650 struct range_list *res_rl;
651 struct data_range *left_drange, *right_drange;
652 sval_t res;
653
654 if (!left_rl || !right_rl)
655 return NULL;
656 if (has_actual_ranges(left_rl))
657 return NULL;
658 if (has_actual_ranges(right_rl))
659 return NULL;
660
661 if (ptr_list_size((struct ptr_list *)left_rl) * ptr_list_size((struct ptr_list *)right_rl) > 20)
662 return NULL;
663
664 res_rl = NULL;
665
666 FOR_EACH_PTR(left_rl, left_drange) {
667 FOR_EACH_PTR(right_rl, right_drange) {
668 if ((op == '%' || op == '/') &&
669 right_drange->min.value == 0)
670 return NULL;
671 res = sval_binop(left_drange->min, op, right_drange->min);
672 add_range(&res_rl, res, res);
673 } END_FOR_EACH_PTR(right_drange);
674 } END_FOR_EACH_PTR(left_drange);
675
676 return res_rl;
677 }
678
679 static bool handle_binop_rl_helper(struct expression *expr, int implied, int *recurse_cnt, struct range_list **res, sval_t *res_sval)
680 {
681 struct symbol *type;
682 struct range_list *left_rl = NULL;
683 struct range_list *right_rl = NULL;
684 struct range_list *rl;
685 sval_t min, max;
686
687 type = get_promoted_type(get_type(expr->left), get_type(expr->right));
688 get_rl_internal(expr->left, implied, recurse_cnt, &left_rl);
689 left_rl = cast_rl(type, left_rl);
690 get_rl_internal(expr->right, implied, recurse_cnt, &right_rl);
691 right_rl = cast_rl(type, right_rl);
692
693 rl = handle_implied_binop(left_rl, expr->op, right_rl);
694 if (rl) {
695 *res = rl;
696 return true;
697 }
698
699 switch (expr->op) {
700 case '%':
701 return handle_mod_rl(expr, implied, recurse_cnt, res);
702 case '&':
703 return handle_bitwise_AND(expr, implied, recurse_cnt, res);
704 case '|':
705 case '^':
706 return use_rl_binop(expr, implied, recurse_cnt, res);
707 case SPECIAL_RIGHTSHIFT:
708 return handle_right_shift(expr, implied, recurse_cnt, res);
709 case SPECIAL_LEFTSHIFT:
710 return handle_left_shift(expr, implied, recurse_cnt, res);
711 case '+':
712 return handle_add_rl(expr, implied, recurse_cnt, res);
713 case '-':
714 return handle_subtract_rl(expr, implied, recurse_cnt, res);
715 case '/':
716 return handle_divide_rl(expr, implied, recurse_cnt, res);
717 }
718
719 if (!left_rl || !right_rl)
720 return false;
721
722 if (sval_binop_overflows(rl_min(left_rl), expr->op, rl_min(right_rl)))
723 return false;
724 if (sval_binop_overflows(rl_max(left_rl), expr->op, rl_max(right_rl)))
725 return false;
726
727 min = sval_binop(rl_min(left_rl), expr->op, rl_min(right_rl));
728 max = sval_binop(rl_max(left_rl), expr->op, rl_max(right_rl));
729
730 *res = alloc_rl(min, max);
731 return true;
732
733 }
734
735 static bool handle_binop_rl(struct expression *expr, int implied, int *recurse_cnt, struct range_list **res, sval_t *res_sval)
736 {
737 struct smatch_state *state;
738 struct range_list *rl;
739 sval_t val;
740
741 if (expr->sval) {
742 *res_sval = *expr->sval;
743 return true;
744 }
745
746 if (handle_known_binop(expr, &val)) {
747 expr->sval = malloc(sizeof(sval_t));
748 *expr->sval = val;
749 *res_sval = val;
750 return true;
751 }
752 if (implied == RL_EXACT)
753 return false;
754
755 if (custom_handle_variable) {
756 rl = custom_handle_variable(expr);
757 if (rl) {
758 *res = rl;
759 return true;
760 }
761 }
762
763 state = get_extra_state(expr);
764 if (state && !is_whole_rl(estate_rl(state))) {
765 if (implied != RL_HARD || estate_has_hard_max(state)) {
766 *res = clone_rl(estate_rl(state));
767 return true;
768 }
769 }
770
771 return handle_binop_rl_helper(expr, implied, recurse_cnt, res, res_sval);
772 }
773
774 static int do_comparison(struct expression *expr)
775 {
776 struct range_list *left_ranges = NULL;
777 struct range_list *right_ranges = NULL;
778 int poss_true, poss_false;
779 struct symbol *type;
780
781 type = get_type(expr);
782 get_absolute_rl(expr->left, &left_ranges);
783 get_absolute_rl(expr->right, &right_ranges);
784
785 left_ranges = cast_rl(type, left_ranges);
786 right_ranges = cast_rl(type, right_ranges);
787
788 poss_true = possibly_true_rl(left_ranges, expr->op, right_ranges);
789 poss_false = possibly_false_rl(left_ranges, expr->op, right_ranges);
790
791 if (!poss_true && !poss_false)
792 return 0x0;
793 if (poss_true && !poss_false)
794 return 0x1;
795 if (!poss_true && poss_false)
796 return 0x2;
797 return 0x3;
798 }
799
800 static bool handle_comparison_rl(struct expression *expr, int implied, int *recurse_cnt, struct range_list **res, sval_t *res_sval)
801 {
802 sval_t left, right;
803 int cmp;
804
805 if (expr->op == SPECIAL_EQUAL && expr->left->type == EXPR_TYPE) {
806 struct symbol *left, *right;
807
808 if (expr->right->type != EXPR_TYPE)
809 return false;
810
811 left = get_real_base_type(expr->left->symbol);
812 right = get_real_base_type(expr->right->symbol);
813 if (type_bits(left) == type_bits(right) &&
814 type_positive_bits(left) == type_positive_bits(right))
815 *res_sval = one;
816 else
817 *res_sval = zero;
818 return true;
819 }
820
821 if (get_value(expr->left, &left) && get_value(expr->right, &right)) {
822 struct data_range tmp_left, tmp_right;
823
824 tmp_left.min = left;
825 tmp_left.max = left;
826 tmp_right.min = right;
827 tmp_right.max = right;
828 if (true_comparison_range(&tmp_left, expr->op, &tmp_right))
829 *res_sval = one;
830 else
831 *res_sval = zero;
832 return true;
833 }
834
835 if (implied == RL_EXACT)
836 return false;
837
838 cmp = do_comparison(expr);
839 if (cmp == 1) {
840 *res_sval = one;
841 return true;
842 }
843 if (cmp == 2) {
844 *res_sval = zero;
845 return true;
846 }
847
848 *res = alloc_rl(zero, one);
849 return true;
850 }
851
852 static bool handle_logical_rl(struct expression *expr, int implied, int *recurse_cnt, struct range_list **res, sval_t *res_sval)
853 {
854 sval_t left, right;
855 int left_known = 0;
856 int right_known = 0;
857
858 if (implied == RL_EXACT) {
859 if (get_value(expr->left, &left))
860 left_known = 1;
861 if (get_value(expr->right, &right))
862 right_known = 1;
863 } else {
864 if (get_implied_value_internal(expr->left, recurse_cnt, &left))
865 left_known = 1;
866 if (get_implied_value_internal(expr->right, recurse_cnt, &right))
867 right_known = 1;
868 }
869
870 switch (expr->op) {
871 case SPECIAL_LOGICAL_OR:
872 if (left_known && left.value)
873 goto one;
874 if (right_known && right.value)
875 goto one;
876 if (left_known && right_known)
877 goto zero;
878 break;
879 case SPECIAL_LOGICAL_AND:
880 if (left_known && right_known) {
881 if (left.value && right.value)
882 goto one;
883 goto zero;
884 }
885 break;
886 default:
887 return false;
888 }
889
890 if (implied == RL_EXACT)
891 return false;
892
893 *res = alloc_rl(zero, one);
894 return true;
895
896 zero:
897 *res_sval = zero;
898 return true;
899 one:
900 *res_sval = one;
901 return true;
902 }
903
904 static bool handle_conditional_rl(struct expression *expr, int implied, int *recurse_cnt, struct range_list **res, sval_t *res_sval)
905 {
906 struct expression *cond_true;
907 struct range_list *true_rl, *false_rl;
908 struct symbol *type;
909 int final_pass_orig = final_pass;
910
911 cond_true = expr->cond_true;
912 if (!cond_true)
913 cond_true = expr->conditional;
914
915 if (known_condition_true(expr->conditional))
916 return get_rl_sval(cond_true, implied, recurse_cnt, res, res_sval);
917 if (known_condition_false(expr->conditional))
918 return get_rl_sval(expr->cond_false, implied, recurse_cnt, res, res_sval);
919
920 if (implied == RL_EXACT)
921 return false;
922
923 if (implied_condition_true(expr->conditional))
924 return get_rl_sval(cond_true, implied, recurse_cnt, res, res_sval);
925 if (implied_condition_false(expr->conditional))
926 return get_rl_sval(expr->cond_false, implied, recurse_cnt, res, res_sval);
927
928 /* this becomes a problem with deeply nested conditional statements */
929 if (fast_math_only || low_on_memory())
930 return false;
931
932 type = get_type(expr);
933
934 __push_fake_cur_stree();
935 final_pass = 0;
936 __split_whole_condition(expr->conditional);
937 true_rl = NULL;
938 get_rl_internal(cond_true, implied, recurse_cnt, &true_rl);
939 __push_true_states();
940 __use_false_states();
941 false_rl = NULL;
942 get_rl_internal(expr->cond_false, implied, recurse_cnt, &false_rl);
943 __merge_true_states();
944 __free_fake_cur_stree();
945 final_pass = final_pass_orig;
946
947 if (!true_rl || !false_rl)
948 return false;
949 true_rl = cast_rl(type, true_rl);
950 false_rl = cast_rl(type, false_rl);
951
952 *res = rl_union(true_rl, false_rl);
953 return true;
954 }
955
956 static bool get_fuzzy_max_helper(struct expression *expr, sval_t *max)
957 {
958 struct smatch_state *state;
959 sval_t sval;
960
961 if (get_hard_max(expr, &sval)) {
962 *max = sval;
963 return true;
964 }
965
966 state = get_extra_state(expr);
967 if (!state || !estate_has_fuzzy_max(state))
968 return false;
969 *max = sval_cast(get_type(expr), estate_get_fuzzy_max(state));
970 return true;
971 }
972
973 static bool get_fuzzy_min_helper(struct expression *expr, sval_t *min)
974 {
975 struct smatch_state *state;
976 sval_t sval;
977
978 state = get_extra_state(expr);
979 if (!state || !estate_rl(state))
980 return false;
981
982 sval = estate_min(state);
983 if (sval_is_negative(sval) && sval_is_min(sval))
984 return false;
985
986 if (sval_is_max(sval))
987 return false;
988
989 *min = sval_cast(get_type(expr), sval);
990 return true;
991 }
992
993 int get_const_value(struct expression *expr, sval_t *sval)
994 {
995 struct symbol *sym;
996 sval_t right;
997
998 if (expr->type != EXPR_SYMBOL || !expr->symbol)
999 return 0;
1000 sym = expr->symbol;
1001 if (!(sym->ctype.modifiers & MOD_CONST))
1002 return 0;
1003 if (get_value(sym->initializer, &right)) {
1004 *sval = sval_cast(get_type(expr), right);
1005 return 1;
1006 }
1007 return 0;
1008 }
1009
1010 struct range_list *var_to_absolute_rl(struct expression *expr)
1011 {
1012 struct smatch_state *state;
1013 struct range_list *rl;
1014
1015 state = get_extra_state(expr);
1016 if (!state || is_whole_rl(estate_rl(state))) {
1017 state = get_real_absolute_state(expr);
1018 if (state && state->data && !estate_is_whole(state))
1019 return clone_rl(estate_rl(state));
1020 if (get_mtag_rl(expr, &rl))
1021 return rl;
1022 if (get_db_type_rl(expr, &rl) && !is_whole_rl(rl))
1023 return rl;
1024 return alloc_whole_rl(get_type(expr));
1025 }
1026 /* err on the side of saying things are possible */
1027 if (!estate_rl(state))
1028 return alloc_whole_rl(get_type(expr));
1029 return clone_rl(estate_rl(state));
1030 }
1031
1032 static bool is_param_sym(struct expression *expr)
1033 {
1034 if (expr->type != EXPR_SYMBOL)
1035 return false;
1036 if (get_param_num(expr) < 0)
1037 return false;
1038 return true;
1039 }
1040
1041 static bool handle_variable(struct expression *expr, int implied, int *recurse_cnt, struct range_list **res, sval_t *res_sval)
1042 {
1043 struct smatch_state *state;
1044 struct range_list *rl;
1045 sval_t sval, min, max;
1046 struct symbol *type;
1047
1048 if (get_const_value(expr, &sval)) {
1049 *res_sval = sval;
1050 return true;
1051 }
1052
1053 if (implied == RL_EXACT)
1054 return false;
1055
1056 if (custom_handle_variable) {
1057 rl = custom_handle_variable(expr);
1058 if (rl) {
1059 if (!rl_to_sval(rl, res_sval))
1060 *res = rl;
1061 } else {
1062 *res = var_to_absolute_rl(expr);
1063 }
1064 return true;
1065 }
1066
1067 if (get_mtag_sval(expr, &sval)) {
1068 *res_sval = sval;
1069 return true;
1070 }
1071
1072 type = get_type(expr);
1073 if (type &&
1074 ((type->type == SYM_ARRAY && !is_param_sym(expr)) ||
1075 type->type == SYM_FN))
1076 return handle_address(expr, implied, recurse_cnt, res, res_sval);
1077
1078 /* FIXME: call rl_to_sval() on the results */
1079
1080 switch (implied) {
1081 case RL_HARD:
1082 case RL_IMPLIED:
1083 case RL_ABSOLUTE:
1084 state = get_extra_state(expr);
1085 if (!state) {
1086 if (implied == RL_HARD)
1087 return false;
1088 if (get_mtag_rl(expr, res))
1089 return true;
1090 if (get_db_type_rl(expr, res))
1091 return true;
1092 if (is_array(expr) && get_array_rl(expr, res))
1093 return true;
1094 return false;
1095 }
1096 if (implied == RL_HARD && !estate_has_hard_max(state))
1097 return false;
1098 *res = clone_rl(estate_rl(state));
1099 return true;
1100 case RL_REAL_ABSOLUTE: {
1101 struct smatch_state *abs_state;
1102
1103 state = get_extra_state(expr);
1104 abs_state = get_real_absolute_state(expr);
1105
1106 if (estate_rl(state) && estate_rl(abs_state)) {
1107 *res = clone_rl(rl_intersection(estate_rl(state),
1108 estate_rl(abs_state)));
1109 return true;
1110 } else if (estate_rl(state)) {
1111 *res = clone_rl(estate_rl(state));
1112 return true;
1113 } else if (estate_is_empty(state)) {
1114 /*
1115 * FIXME: we don't handle empty extra states correctly.
1116 *
1117 * The real abs rl is supposed to be filtered by the
1118 * extra state if there is one. We don't bother keeping
1119 * the abs state in sync all the time because we know it
1120 * will be filtered later.
1121 *
1122 * It's not totally obvious to me how they should be
1123 * handled. Perhaps we should take the whole rl and
1124 * filter by the imaginary states. Perhaps we should
1125 * just go with the empty state.
1126 *
1127 * Anyway what we currently do is return NULL here and
1128 * that gets translated into the whole range in
1129 * get_real_absolute_rl().
1130 *
1131 */
1132 return false;
1133 } else if (estate_rl(abs_state)) {
1134 *res = clone_rl(estate_rl(abs_state));
1135 return true;
1136 }
1137
1138 if (get_mtag_rl(expr, res))
1139 return true;
1140 if (get_db_type_rl(expr, res))
1141 return true;
1142 if (is_array(expr) && get_array_rl(expr, res))
1143 return true;
1144 return false;
1145 }
1146 case RL_FUZZY:
1147 if (!get_fuzzy_min_helper(expr, &min))
1148 min = sval_type_min(get_type(expr));
1149 if (!get_fuzzy_max_helper(expr, &max))
1150 return false;
1151 /* fuzzy ranges are often inverted */
1152 if (sval_cmp(min, max) > 0) {
1153 sval = min;
1154 min = max;
1155 max = sval;
1156 }
1157 *res = alloc_rl(min, max);
1158 return true;
1159 }
1160 return false;
1161 }
1162
1163 static sval_t handle_sizeof(struct expression *expr)
1164 {
1165 struct symbol *sym;
1166 sval_t ret;
1167
1168 ret = sval_blank(expr);
1169 sym = expr->cast_type;
1170 if (!sym) {
1171 sym = evaluate_expression(expr->cast_expression);
1172 if (!sym) {
1173 __silence_warnings_for_stmt = true;
1174 sym = &int_ctype;
1175 }
1176 #if 0
1177 /*
1178 * Expressions of restricted types will possibly get
1179 * promoted - check that here. I'm not sure how this works,
1180 * the problem is that sizeof(le16) shouldn't be promoted and
1181 * the original code did that... Let's if zero this out and
1182 * see what breaks.
1183 */
1184
1185 if (is_restricted_type(sym)) {
1186 if (type_bits(sym) < bits_in_int)
1187 sym = &int_ctype;
1188 }
1189 #endif
1190 if (is_fouled_type(sym))
1191 sym = &int_ctype;
1192 }
1193 examine_symbol_type(sym);
1194
1195 ret.type = size_t_ctype;
1196 if (type_bits(sym) <= 0) /* sizeof(void) */ {
1197 if (get_real_base_type(sym) == &void_ctype)
1198 ret.value = 1;
1199 else
1200 ret.value = 0;
1201 } else
1202 ret.value = type_bytes(sym);
1203
1204 return ret;
1205 }
1206
1207 static bool handle_strlen(struct expression *expr, int implied, int *recurse_cnt, struct range_list **res, sval_t *res_sval)
1208 {
1209 struct expression *arg, *tmp;
1210 sval_t tag;
1211 sval_t ret = { .type = &ulong_ctype };
1212 struct range_list *rl;
1213
1214 arg = get_argument_from_call_expr(expr->args, 0);
1215 if (!arg)
1216 return false;
1217 if (arg->type == EXPR_STRING) {
1218 ret.value = arg->string->length - 1;
1219 *res_sval = ret;
1220 return true;
1221 }
1222 if (implied == RL_EXACT)
1223 return false;
1224 if (get_implied_value(arg, &tag) &&
1225 (tmp = fake_string_from_mtag(tag.uvalue))) {
1226 ret.value = tmp->string->length - 1;
1227 *res_sval = ret;
1228 return true;
1229 }
1230
1231 if (implied == RL_HARD || implied == RL_FUZZY)
1232 return false;
1233
1234 if (get_implied_return(expr, &rl)) {
1235 *res = rl;
1236 return true;
1237 }
1238
1239 return false;
1240 }
1241
1242 static bool handle_builtin_constant_p(struct expression *expr, int implied, int *recurse_cnt, sval_t *res_sval)
1243 {
1244 struct expression *arg;
1245 struct range_list *rl;
1246
1247 arg = get_argument_from_call_expr(expr->args, 0);
1248 if (get_rl_internal(arg, RL_EXACT, recurse_cnt, &rl))
1249 *res_sval = one;
1250 else
1251 *res_sval = zero;
1252 return true;
1253 }
1254
1255 static bool handle__builtin_choose_expr(struct expression *expr, int implied, int *recurse_cnt, struct range_list **res, sval_t *res_sval)
1256 {
1257 struct expression *const_expr, *expr1, *expr2;
1258 sval_t sval;
1259
1260 const_expr = get_argument_from_call_expr(expr->args, 0);
1261 expr1 = get_argument_from_call_expr(expr->args, 1);
1262 expr2 = get_argument_from_call_expr(expr->args, 2);
1263
1264 if (!get_value(const_expr, &sval) || !expr1 || !expr2)
1265 return false;
1266 if (sval.value)
1267 return get_rl_sval(expr1, implied, recurse_cnt, res, res_sval);
1268 else
1269 return get_rl_sval(expr2, implied, recurse_cnt, res, res_sval);
1270 }
1271
1272 int smatch_fls(unsigned long long value)
1273 {
1274 int i;
1275
1276 for (i = 63; i >= 0; i--) {
1277 if (value & 1ULL << i)
1278 return i + 1;
1279 }
1280 return 0;
1281 }
1282
1283 static bool handle_ffs(struct expression *expr, int implied, int *recurse_cnt, struct range_list **res, sval_t *res_sval)
1284 {
1285 struct expression *arg;
1286 struct bit_info *bits;
1287 sval_t high = { .type = &int_ctype };
1288 sval_t low = { .type = &int_ctype };
1289
1290 arg = get_argument_from_call_expr(expr->args, 0);
1291
1292 bits = get_bit_info(arg);
1293 if (bits->possible == 0) {
1294 high.value = 0;
1295 *res_sval = high;
1296 return true;
1297 }
1298
1299 high.value = ffsll(bits->set);
1300 if (!high.value)
1301 high.value = smatch_fls(bits->possible);
1302
1303 low.value = ffsll(bits->possible);
1304
1305 *res = alloc_rl(low, high);
1306 return false;
1307 }
1308
1309 static bool handle_call_rl(struct expression *expr, int implied, int *recurse_cnt, struct range_list **res, sval_t *res_sval)
1310 {
1311 struct range_list *rl;
1312
1313 if (sym_name_is("__builtin_constant_p", expr->fn))
1314 return handle_builtin_constant_p(expr, implied, recurse_cnt, res_sval);
1315
1316 if (sym_name_is("__builtin_choose_expr", expr->fn))
1317 return handle__builtin_choose_expr(expr, implied, recurse_cnt, res, res_sval);
1318
1319 if (sym_name_is("__builtin_expect", expr->fn) ||
1320 sym_name_is("__builtin_bswap16", expr->fn) ||
1321 sym_name_is("__builtin_bswap32", expr->fn) ||
1322 sym_name_is("__builtin_bswap64", expr->fn)) {
1323 struct expression *arg;
1324
1325 arg = get_argument_from_call_expr(expr->args, 0);
1326 return get_rl_sval(arg, implied, recurse_cnt, res, res_sval);
1327 }
1328
1329 if (sym_name_is("__builtin_ffs", expr->fn) ||
1330 sym_name_is("__builtin_ffsl", expr->fn) ||
1331 sym_name_is("__builtin_ffsll", expr->fn))
1332 return handle_ffs(expr, implied, recurse_cnt, res, res_sval);
1333
1334 if (sym_name_is("strlen", expr->fn))
1335 return handle_strlen(expr, implied, recurse_cnt, res, res_sval);
1336
1337 if (implied == RL_EXACT || implied == RL_HARD)
1338 return false;
1339
1340 if (custom_handle_variable) {
1341 rl = custom_handle_variable(expr);
1342 if (rl) {
1343 *res = rl;
1344 return true;
1345 }
1346 }
1347
1348 /* Ugh... get_implied_return() sets *rl to NULL on failure */
1349 if (get_implied_return(expr, &rl)) {
1350 *res = rl;
1351 return true;
1352 }
1353 rl = db_return_vals(expr);
1354 if (rl) {
1355 *res = rl;
1356 return true;
1357 }
1358 return false;
1359 }
1360
1361 static bool handle_cast(struct expression *expr, int implied, int *recurse_cnt, struct range_list **res, sval_t *res_sval)
1362 {
1363 struct range_list *rl;
1364 struct symbol *type;
1365 sval_t sval = {};
1366
1367 type = get_type(expr);
1368 if (get_rl_sval(expr->cast_expression, implied, recurse_cnt, &rl, &sval)) {
1369 if (sval.type)
1370 *res_sval = sval_cast(type, sval);
1371 else
1372 *res = cast_rl(type, rl);
1373 return true;
1374 }
1375 if (implied == RL_ABSOLUTE || implied == RL_REAL_ABSOLUTE) {
1376 *res = alloc_whole_rl(type);
1377 return true;
1378 }
1379 if (implied == RL_IMPLIED && type &&
1380 type_bits(type) > 0 && type_bits(type) < 32) {
1381 *res = alloc_whole_rl(type);
1382 return true;
1383 }
1384 return false;
1385 }
1386
1387 static bool get_offset_from_down(struct expression *expr, int implied, int *recurse_cnt, struct range_list **res, sval_t *res_sval)
1388 {
1389 struct expression *index;
1390 struct symbol *type = expr->in;
1391 struct range_list *rl;
1392 struct symbol *field;
1393 int offset = 0;
1394 sval_t sval = { .type = ssize_t_ctype };
1395 sval_t tmp_sval = {};
1396
1397 /*
1398 * FIXME: I don't really know what I'm doing here. I wish that I
1399 * could just get rid of the __builtin_offset() function and use:
1400 * "&((struct bpf_prog *)NULL)->insns[fprog->len]" instead...
1401 * Anyway, I have done the minimum ammount of work to get that
1402 * expression to work.
1403 *
1404 */
1405
1406 if (expr->op != '.' || !expr->down ||
1407 expr->down->type != EXPR_OFFSETOF ||
1408 expr->down->op != '[' ||
1409 !expr->down->index)
1410 return false;
1411
1412 index = expr->down->index;
1413
1414 examine_symbol_type(type);
1415 type = get_real_base_type(type);
1416 if (!type)
1417 return false;
1418 field = find_identifier(expr->ident, type->symbol_list, &offset);
1419 if (!field)
1420 return false;
1421
1422 type = get_real_base_type(field);
1423 if (!type || type->type != SYM_ARRAY)
1424 return false;
1425 type = get_real_base_type(type);
1426
1427 if (get_implied_value_internal(index, recurse_cnt, &sval)) {
1428 res_sval->type = ssize_t_ctype;
1429 res_sval->value = offset + sval.value * type_bytes(type);
1430 return true;
1431 }
1432
1433 if (!get_rl_sval(index, implied, recurse_cnt, &rl, &tmp_sval))
1434 return false;
1435
1436 /*
1437 * I'm not sure why get_rl_sval() would return an sval when
1438 * get_implied_value_internal() failed but it does when I
1439 * parse drivers/net/ethernet/mellanox/mlx5/core/en/monitor_stats.c
1440 *
1441 */
1442 if (tmp_sval.type) {
1443 res_sval->type = ssize_t_ctype;
1444 res_sval->value = offset + sval.value * type_bytes(type);
1445 return true;
1446 }
1447
1448 sval.value = type_bytes(type);
1449 rl = rl_binop(rl, '*', alloc_rl(sval, sval));
1450 sval.value = offset;
1451 *res = rl_binop(rl, '+', alloc_rl(sval, sval));
1452 return true;
1453 }
1454
1455 static bool get_offset_from_in(struct expression *expr, int implied, int *recurse_cnt, struct range_list **res, sval_t *res_sval)
1456 {
1457 struct symbol *type = get_real_base_type(expr->in);
1458 struct symbol *field;
1459 int offset = 0;
1460
1461 if (expr->op != '.' || !type || !expr->ident)
1462 return false;
1463
1464 field = find_identifier(expr->ident, type->symbol_list, &offset);
1465 if (!field)
1466 return false;
1467
1468 res_sval->type = size_t_ctype;
1469 res_sval->value = offset;
1470
1471 return true;
1472 }
1473
1474 static bool handle_offsetof_rl(struct expression *expr, int implied, int *recurse_cnt, struct range_list **res, sval_t *res_sval)
1475 {
1476 if (get_offset_from_down(expr, implied, recurse_cnt, res, res_sval))
1477 return true;
1478
1479 if (get_offset_from_in(expr, implied, recurse_cnt, res, res_sval))
1480 return true;
1481
1482 evaluate_expression(expr);
1483 if (expr->type == EXPR_VALUE) {
1484 *res_sval = sval_from_val(expr, expr->value);
1485 return true;
1486 }
1487 return false;
1488 }
1489
1490 static bool get_rl_sval(struct expression *expr, int implied, int *recurse_cnt, struct range_list **res, sval_t *sval_res)
1491 {
1492 struct range_list *rl = (void *)-1UL;
1493 struct symbol *type;
1494 sval_t sval = {};
1495
1496 type = get_type(expr);
1497 expr = strip_parens(expr);
1498 if (!expr)
1499 return false;
1500
1501 if (++(*recurse_cnt) >= 200)
1502 return false;
1503
1504 switch(expr->type) {
1505 case EXPR_CAST:
1506 case EXPR_FORCE_CAST:
1507 case EXPR_IMPLIED_CAST:
1508 handle_cast(expr, implied, recurse_cnt, &rl, &sval);
1509 goto out_cast;
1510 }
1511
1512 expr = strip_expr(expr);
1513 if (!expr)
1514 return false;
1515
1516 switch (expr->type) {
1517 case EXPR_VALUE:
1518 sval = sval_from_val(expr, expr->value);
1519 break;
1520 case EXPR_FVALUE:
1521 sval = sval_from_fval(expr, expr->fvalue);
1522 break;
1523 case EXPR_PREOP:
1524 handle_preop_rl(expr, implied, recurse_cnt, &rl, &sval);
1525 break;
1526 case EXPR_POSTOP:
1527 get_rl_sval(expr->unop, implied, recurse_cnt, &rl, &sval);
1528 break;
1529 case EXPR_BINOP:
1530 handle_binop_rl(expr, implied, recurse_cnt, &rl, &sval);
1531 break;
1532 case EXPR_COMPARE:
1533 handle_comparison_rl(expr, implied, recurse_cnt, &rl, &sval);
1534 break;
1535 case EXPR_LOGICAL:
1536 handle_logical_rl(expr, implied, recurse_cnt, &rl, &sval);
1537 break;
1538 case EXPR_PTRSIZEOF:
1539 case EXPR_SIZEOF:
1540 sval = handle_sizeof(expr);
1541 break;
1542 case EXPR_SELECT:
1543 case EXPR_CONDITIONAL:
1544 handle_conditional_rl(expr, implied, recurse_cnt, &rl, &sval);
1545 break;
1546 case EXPR_CALL:
1547 handle_call_rl(expr, implied, recurse_cnt, &rl, &sval);
1548 break;
1549 case EXPR_STRING:
1550 if (get_mtag_sval(expr, &sval))
1551 break;
1552 if (implied == RL_EXACT)
1553 break;
1554 rl = alloc_rl(valid_ptr_min_sval, valid_ptr_max_sval);
1555 break;
1556 case EXPR_OFFSETOF:
1557 handle_offsetof_rl(expr, implied, recurse_cnt, &rl, &sval);
1558 break;
1559 case EXPR_ALIGNOF:
1560 evaluate_expression(expr);
1561 if (expr->type == EXPR_VALUE)
1562 sval = sval_from_val(expr, expr->value);
1563 break;
1564 default:
1565 handle_variable(expr, implied, recurse_cnt, &rl, &sval);
1566 }
1567
1568 out_cast:
1569 if (rl == (void *)-1UL)
1570 rl = NULL;
1571
1572 if (sval.type || (rl && rl_to_sval(rl, &sval))) {
1573 *sval_res = sval;
1574 return true;
1575 }
1576 if (implied == RL_EXACT)
1577 return false;
1578
1579 if (rl) {
1580 *res = rl;
1581 return true;
1582 }
1583 if (type && (implied == RL_ABSOLUTE || implied == RL_REAL_ABSOLUTE)) {
1584 *res = alloc_whole_rl(type);
1585 return true;
1586 }
1587 return false;
1588 }
1589
1590 static bool get_rl_internal(struct expression *expr, int implied, int *recurse_cnt, struct range_list **res)
1591 {
1592 struct range_list *rl = NULL;
1593 sval_t sval = {};
1594
1595 if (!get_rl_sval(expr, implied, recurse_cnt, &rl, &sval))
1596 return false;
1597
1598 if (sval.type)
1599 *res = alloc_rl(sval, sval);
1600 else
1601 *res = rl;
1602 return true;
1603 }
1604
1605 static bool get_rl_helper(struct expression *expr, int implied, struct range_list **res)
1606 {
1607 struct range_list *rl = NULL;
1608 sval_t sval = {};
1609 int recurse_cnt = 0;
1610
1611 if (get_value(expr, &sval)) {
1612 *res = alloc_rl(sval, sval);
1613 return true;
1614 }
1615
1616 if (!get_rl_sval(expr, implied, &recurse_cnt, &rl, &sval))
1617 return false;
1618
1619 if (sval.type)
1620 *res = alloc_rl(sval, sval);
1621 else
1622 *res = rl;
1623 return true;
1624 }
1625
1626 struct {
1627 struct expression *expr;
1628 sval_t sval;
1629 } cached_results[24];
1630 static int cache_idx;
1631
1632 void clear_math_cache(void)
1633 {
1634 memset(cached_results, 0, sizeof(cached_results));
1635 }
1636
1637 void set_fast_math_only(void)
1638 {
1639 fast_math_only++;
1640 }
1641
1642 void clear_fast_math_only(void)
1643 {
1644 fast_math_only--;
1645 }
1646
1647 /*
1648 * Don't cache EXPR_VALUE because values are fast already.
1649 *
1650 */
1651 static bool get_value_literal(struct expression *expr, sval_t *res_sval)
1652 {
1653 struct expression *tmp;
1654 int recurse_cnt = 0;
1655
1656 tmp = strip_expr(expr);
1657 if (!tmp || tmp->type != EXPR_VALUE)
1658 return false;
1659
1660 return get_rl_sval(expr, RL_EXACT, &recurse_cnt, NULL, res_sval);
1661 }
1662
1663 /* returns 1 if it can get a value literal or else returns 0 */
1664 int get_value(struct expression *expr, sval_t *res_sval)
1665 {
1666 struct range_list *(*orig_custom_fn)(struct expression *expr);
1667 int recurse_cnt = 0;
1668 sval_t sval = {};
1669 int i;
1670
1671 if (get_value_literal(expr, res_sval))
1672 return 1;
1673
1674 /*
1675 * This only handles RL_EXACT because other expr statements can be
1676 * different at different points. Like the list iterator, for example.
1677 */
1678 for (i = 0; i < ARRAY_SIZE(cached_results); i++) {
1679 if (expr == cached_results[i].expr) {
1680 if (cached_results[i].sval.type) {
1681 *res_sval = cached_results[i].sval;
1682 return true;
1683 }
1684 return false;
1685 }
1686 }
1687
1688 orig_custom_fn = custom_handle_variable;
1689 custom_handle_variable = NULL;
1690 get_rl_sval(expr, RL_EXACT, &recurse_cnt, NULL, &sval);
1691
1692 custom_handle_variable = orig_custom_fn;
1693
1694 cached_results[cache_idx].expr = expr;
1695 cached_results[cache_idx].sval = sval;
1696 cache_idx = (cache_idx + 1) % ARRAY_SIZE(cached_results);
1697
1698 if (!sval.type)
1699 return 0;
1700
1701 *res_sval = sval;
1702 return 1;
1703 }
1704
1705 static bool get_implied_value_internal(struct expression *expr, int *recurse_cnt, sval_t *res_sval)
1706 {
1707 struct range_list *rl;
1708
1709 res_sval->type = NULL;
1710
1711 if (!get_rl_sval(expr, RL_IMPLIED, recurse_cnt, &rl, res_sval))
1712 return false;
1713 if (!res_sval->type && !rl_to_sval(rl, res_sval))
1714 return false;
1715 return true;
1716 }
1717
1718 int get_implied_value(struct expression *expr, sval_t *sval)
1719 {
1720 struct range_list *rl;
1721
1722 if (!get_rl_helper(expr, RL_IMPLIED, &rl) ||
1723 !rl_to_sval(rl, sval))
1724 return 0;
1725 return 1;
1726 }
1727
1728 int get_implied_value_fast(struct expression *expr, sval_t *sval)
1729 {
1730 struct range_list *rl;
1731 static int recurse;
1732 int ret = 0;
1733
1734 if (recurse)
1735 return 0;
1736
1737 recurse = 1;
1738 set_fast_math_only();
1739 if (get_rl_helper(expr, RL_IMPLIED, &rl) &&
1740 rl_to_sval(rl, sval))
1741 ret = 1;
1742 clear_fast_math_only();
1743 recurse = 0;
1744
1745 return ret;
1746 }
1747
1748 int get_implied_min(struct expression *expr, sval_t *sval)
1749 {
1750 struct range_list *rl;
1751
1752 if (!get_rl_helper(expr, RL_IMPLIED, &rl) || !rl)
1753 return 0;
1754 *sval = rl_min(rl);
1755 return 1;
1756 }
1757
1758 int get_implied_max(struct expression *expr, sval_t *sval)
1759 {
1760 struct range_list *rl;
1761
1762 if (!get_rl_helper(expr, RL_IMPLIED, &rl) || !rl)
1763 return 0;
1764 *sval = rl_max(rl);
1765 return 1;
1766 }
1767
1768 int get_implied_rl(struct expression *expr, struct range_list **rl)
1769 {
1770 if (!get_rl_helper(expr, RL_IMPLIED, rl) || !*rl)
1771 return 0;
1772 return 1;
1773 }
1774
1775 static int get_absolute_rl_internal(struct expression *expr, struct range_list **rl, int *recurse_cnt)
1776 {
1777 *rl = NULL;
1778 get_rl_internal(expr, RL_ABSOLUTE, recurse_cnt, rl);
1779 if (!*rl)
1780 *rl = alloc_whole_rl(get_type(expr));
1781 return 1;
1782 }
1783
1784 int get_absolute_rl(struct expression *expr, struct range_list **rl)
1785 {
1786 *rl = NULL;
1787 get_rl_helper(expr, RL_ABSOLUTE, rl);
1788 if (!*rl)
1789 *rl = alloc_whole_rl(get_type(expr));
1790 return 1;
1791 }
1792
1793 int get_real_absolute_rl(struct expression *expr, struct range_list **rl)
1794 {
1795 *rl = NULL;
1796 get_rl_helper(expr, RL_REAL_ABSOLUTE, rl);
1797 if (!*rl)
1798 *rl = alloc_whole_rl(get_type(expr));
1799 return 1;
1800 }
1801
1802 int custom_get_absolute_rl(struct expression *expr,
1803 struct range_list *(*fn)(struct expression *expr),
1804 struct range_list **rl)
1805 {
1806 int ret;
1807
1808 *rl = NULL;
1809 custom_handle_variable = fn;
1810 ret = get_rl_helper(expr, RL_REAL_ABSOLUTE, rl);
1811 custom_handle_variable = NULL;
1812 return ret;
1813 }
1814
1815 int get_implied_rl_var_sym(const char *var, struct symbol *sym, struct range_list **rl)
1816 {
1817 struct smatch_state *state;
1818
1819 state = get_state(SMATCH_EXTRA, var, sym);
1820 *rl = estate_rl(state);
1821 if (*rl)
1822 return 1;
1823 return 0;
1824 }
1825
1826 int get_hard_max(struct expression *expr, sval_t *sval)
1827 {
1828 struct range_list *rl;
1829
1830 if (!get_rl_helper(expr, RL_HARD, &rl) || !rl)
1831 return 0;
1832 *sval = rl_max(rl);
1833 return 1;
1834 }
1835
1836 int get_fuzzy_min(struct expression *expr, sval_t *sval)
1837 {
1838 struct range_list *rl;
1839 sval_t tmp;
1840
1841 if (!get_rl_helper(expr, RL_FUZZY, &rl) || !rl)
1842 return 0;
1843 tmp = rl_min(rl);
1844 if (sval_is_negative(tmp) && sval_is_min(tmp))
1845 return 0;
1846 *sval = tmp;
1847 return 1;
1848 }
1849
1850 int get_fuzzy_max(struct expression *expr, sval_t *sval)
1851 {
1852 struct range_list *rl;
1853 sval_t max;
1854
1855 if (!get_rl_helper(expr, RL_FUZZY, &rl) || !rl)
1856 return 0;
1857 max = rl_max(rl);
1858 if (max.uvalue > INT_MAX - 10000)
1859 return 0;
1860 *sval = max;
1861 return 1;
1862 }
1863
1864 int get_absolute_min(struct expression *expr, sval_t *sval)
1865 {
1866 struct range_list *rl;
1867 struct symbol *type;
1868
1869 type = get_type(expr);
1870 if (!type)
1871 type = &llong_ctype; // FIXME: this is wrong but places assume get type can't fail.
1872 rl = NULL;
1873 get_rl_helper(expr, RL_REAL_ABSOLUTE, &rl);
1874 if (rl)
1875 *sval = rl_min(rl);
1876 else
1877 *sval = sval_type_min(type);
1878
1879 if (sval_cmp(*sval, sval_type_min(type)) < 0)
1880 *sval = sval_type_min(type);
1881 return 1;
1882 }
1883
1884 int get_absolute_max(struct expression *expr, sval_t *sval)
1885 {
1886 struct range_list *rl;
1887 struct symbol *type;
1888
1889 type = get_type(expr);
1890 if (!type)
1891 type = &llong_ctype;
1892 rl = NULL;
1893 get_rl_helper(expr, RL_REAL_ABSOLUTE, &rl);
1894 if (rl)
1895 *sval = rl_max(rl);
1896 else
1897 *sval = sval_type_max(type);
1898
1899 if (sval_cmp(sval_type_max(type), *sval) < 0)
1900 *sval = sval_type_max(type);
1901 return 1;
1902 }
1903
1904 int known_condition_true(struct expression *expr)
1905 {
1906 sval_t tmp;
1907
1908 if (!expr)
1909 return 0;
1910
1911 if (__inline_fn && get_param_num(expr) >= 0) {
1912 if (get_implied_value(expr, &tmp) && tmp.value)
1913 return 1;
1914 return 0;
1915 }
1916
1917 if (get_value(expr, &tmp) && tmp.value)
1918 return 1;
1919
1920 return 0;
1921 }
1922
1923 int known_condition_false(struct expression *expr)
1924 {
1925 sval_t tmp;
1926
1927 if (!expr)
1928 return 0;
1929
1930 if (__inline_fn && get_param_num(expr) >= 0) {
1931 if (get_implied_value(expr, &tmp) && tmp.value == 0)
1932 return 1;
1933 return 0;
1934 }
1935
1936 if (expr_is_zero(expr))
1937 return 1;
1938
1939 return 0;
1940 }
1941
1942 int implied_condition_true(struct expression *expr)
1943 {
1944 sval_t tmp;
1945
1946 if (!expr)
1947 return 0;
1948
1949 if (known_condition_true(expr))
1950 return 1;
1951 if (get_implied_value(expr, &tmp) && tmp.value)
1952 return 1;
1953
1954 if (expr->type == EXPR_POSTOP)
1955 return implied_condition_true(expr->unop);
1956
1957 if (expr->type == EXPR_PREOP && expr->op == SPECIAL_DECREMENT)
1958 return implied_not_equal(expr->unop, 1);
1959 if (expr->type == EXPR_PREOP && expr->op == SPECIAL_INCREMENT)
1960 return implied_not_equal(expr->unop, -1);
1961
1962 expr = strip_expr(expr);
1963 switch (expr->type) {
1964 case EXPR_COMPARE:
1965 if (do_comparison(expr) == 1)
1966 return 1;
1967 break;
1968 case EXPR_PREOP:
1969 if (expr->op == '!') {
1970 if (implied_condition_false(expr->unop))
1971 return 1;
1972 break;
1973 }
1974 break;
1975 default:
1976 if (implied_not_equal(expr, 0) == 1)
1977 return 1;
1978 break;
1979 }
1980 return 0;
1981 }
1982
1983 int implied_condition_false(struct expression *expr)
1984 {
1985 struct expression *tmp;
1986 sval_t sval;
1987
1988 if (!expr)
1989 return 0;
1990
1991 if (known_condition_false(expr))
1992 return 1;
1993
1994 switch (expr->type) {
1995 case EXPR_COMPARE:
1996 if (do_comparison(expr) == 2)
1997 return 1;
1998 case EXPR_PREOP:
1999 if (expr->op == '!') {
2000 if (implied_condition_true(expr->unop))
2001 return 1;
2002 break;
2003 }
2004 tmp = strip_expr(expr);
2005 if (tmp != expr)
2006 return implied_condition_false(tmp);
2007 break;
2008 default:
2009 if (get_implied_value(expr, &sval) && sval.value == 0)
2010 return 1;
2011 break;
2012 }
2013 return 0;
2014 }
2015
2016
Static analysis for C