4 * Copyright (C) 2010 Dan Carpenter.
6 * Licensed under the Open Software License version 1.1
12 #include "smatch_slist.h"
13 #include "smatch_extra.h"
15 static struct range_list
*_get_rl(struct expression
*expr
, int implied
);
16 static struct range_list
*handle_variable(struct expression
*expr
, int implied
);
18 static sval_t zero
= {.type
= &int_ctype
, {.value
= 0} };
19 static sval_t one
= {.type
= &int_ctype
, {.value
= 1} };
21 static struct range_list
*rl_zero(void)
23 return alloc_rl(zero
, zero
);
26 static struct range_list
*rl_one(void)
28 return alloc_rl(one
, one
);
39 static struct range_list
*last_stmt_rl(struct statement
*stmt
, int implied
)
44 stmt
= last_ptr_list((struct ptr_list
*)stmt
->stmts
);
45 if (stmt
->type
!= STMT_EXPRESSION
)
47 return _get_rl(stmt
->expression
, implied
);
50 static struct range_list
*handle_expression_statement_rl(struct expression
*expr
, int implied
)
52 return last_stmt_rl(get_expression_statement(expr
), implied
);
55 static struct range_list
*handle_ampersand_rl(int implied
)
57 if (implied
== RL_EXACT
|| implied
== RL_HARD
)
59 return alloc_rl(valid_ptr_min_sval
, valid_ptr_max_sval
);
62 static struct range_list
*handle_negate_rl(struct expression
*expr
, int implied
)
64 if (known_condition_true(expr
->unop
))
66 if (known_condition_false(expr
->unop
))
69 if (implied
== RL_EXACT
)
72 if (implied_condition_true(expr
->unop
))
74 if (implied_condition_false(expr
->unop
))
76 return alloc_rl(zero
, one
);
79 static struct range_list
*handle_bitwise_negate(struct expression
*expr
, int implied
)
81 struct range_list
*rl
;
84 rl
= _get_rl(expr
->unop
, implied
);
85 if (!rl_to_sval(rl
, &sval
))
87 sval
= sval_preop(sval
, '~');
88 sval_cast(get_type(expr
->unop
), sval
);
89 return alloc_rl(sval
, sval
);
92 static struct range_list
*handle_minus_preop(struct expression
*expr
, int implied
)
94 struct range_list
*rl
;
97 rl
= _get_rl(expr
->unop
, implied
);
98 if (!rl_to_sval(rl
, &sval
))
100 sval
= sval_preop(sval
, '-');
101 return alloc_rl(sval
, sval
);
104 static struct range_list
*handle_preop_rl(struct expression
*expr
, int implied
)
108 return handle_ampersand_rl(implied
);
110 return handle_negate_rl(expr
, implied
);
112 return handle_bitwise_negate(expr
, implied
);
114 return handle_minus_preop(expr
, implied
);
116 return handle_variable(expr
, implied
);
118 return handle_expression_statement_rl(expr
, implied
);
124 static struct range_list
*handle_divide_rl(struct expression
*expr
, int implied
)
126 struct range_list
*left_rl
, *right_rl
;
130 type
= get_type(expr
);
132 left_rl
= _get_rl(expr
->left
, implied
);
133 left_rl
= cast_rl(type
, left_rl
);
134 right_rl
= _get_rl(expr
->right
, implied
);
135 right_rl
= cast_rl(type
, right_rl
);
137 if (!left_rl
|| !right_rl
)
139 if (is_whole_rl(left_rl
) || is_whole_rl(right_rl
))
141 if (sval_is_negative(rl_min(left_rl
)) || sval_cmp_val(rl_min(right_rl
), 0) <= 0)
144 max
= rl_max(left_rl
);
145 if (!sval_is_max(max
))
146 max
= sval_binop(max
, '/', rl_min(right_rl
));
147 min
= sval_binop(rl_min(left_rl
), '/', rl_max(right_rl
));
148 return alloc_rl(min
, max
);
151 static struct range_list
*handle_subtract_rl(struct expression
*expr
, int implied
)
154 struct range_list
*left_rl
, *right_rl
;
155 sval_t max
, min
, tmp
;
158 type
= get_type(expr
);
159 comparison
= get_comparison(expr
->left
, expr
->right
);
161 left_rl
= _get_rl(expr
->left
, implied
);
162 left_rl
= cast_rl(type
, left_rl
);
163 right_rl
= _get_rl(expr
->right
, implied
);
164 right_rl
= cast_rl(type
, right_rl
);
166 if ((!left_rl
|| !right_rl
) &&
167 (implied
== RL_EXACT
|| implied
== RL_HARD
|| implied
== RL_FUZZY
))
171 left_rl
= alloc_whole_rl(type
);
173 right_rl
= alloc_whole_rl(type
);
175 /* negative values complicate everything fix this later */
176 if (sval_is_negative(rl_min(right_rl
)))
178 max
= rl_max(left_rl
);
180 switch (comparison
) {
182 case SPECIAL_UNSIGNED_GT
:
183 min
= sval_type_val(type
, 1);
184 max
= rl_max(left_rl
);
187 case SPECIAL_UNSIGNED_GTE
:
188 min
= sval_type_val(type
, 0);
189 max
= rl_max(left_rl
);
192 if (sval_binop_overflows(rl_min(left_rl
), '-', rl_max(right_rl
)))
194 min
= sval_type_min(type
);
197 if (!sval_binop_overflows(rl_min(left_rl
), '-', rl_max(right_rl
))) {
198 tmp
= sval_binop(rl_min(left_rl
), '-', rl_max(right_rl
));
199 if (sval_cmp(tmp
, min
) > 0)
203 if (!sval_is_max(rl_max(left_rl
))) {
204 tmp
= sval_binop(rl_max(left_rl
), '-', rl_min(right_rl
));
205 if (sval_cmp(tmp
, max
) < 0)
209 if (sval_is_min(min
) && sval_is_max(max
))
212 return cast_rl(type
, alloc_rl(min
, max
));
215 static struct range_list
*handle_mod_rl(struct expression
*expr
, int implied
)
217 struct range_list
*rl
;
218 sval_t left
, right
, sval
;
220 if (implied
== RL_EXACT
) {
221 if (!get_value(expr
->right
, &right
))
223 if (!get_value(expr
->left
, &left
))
225 sval
= sval_binop(left
, '%', right
);
226 return alloc_rl(sval
, sval
);
228 /* if we can't figure out the right side it's probably hopeless */
229 if (!get_implied_value(expr
->right
, &right
))
232 right
= sval_cast(get_type(expr
), right
);
235 rl
= _get_rl(expr
->left
, implied
);
236 if (rl
&& rl_max(rl
).uvalue
< right
.uvalue
)
237 right
.uvalue
= rl_max(rl
).uvalue
;
239 return alloc_rl(zero
, right
);
242 static struct range_list
*handle_bitwise_AND(struct expression
*expr
, int implied
)
245 struct range_list
*left_rl
, *right_rl
;
247 if (implied
!= RL_IMPLIED
&& implied
!= RL_ABSOLUTE
)
250 type
= get_type(expr
);
252 left_rl
= _get_rl(expr
->left
, implied
);
254 left_rl
= cast_rl(type
, left_rl
);
255 left_rl
= alloc_rl(sval_type_val(type
, 0), rl_max(left_rl
));
257 if (implied
== RL_HARD
)
259 left_rl
= alloc_whole_rl(type
);
262 right_rl
= _get_rl(expr
->right
, implied
);
264 right_rl
= cast_rl(type
, right_rl
);
265 right_rl
= alloc_rl(sval_type_val(type
, 0), rl_max(right_rl
));
267 if (implied
== RL_HARD
)
269 right_rl
= alloc_whole_rl(type
);
272 return rl_intersection(left_rl
, right_rl
);
275 static struct range_list
*handle_right_shift(struct expression
*expr
, int implied
)
277 struct range_list
*left_rl
;
281 if (implied
== RL_EXACT
|| implied
== RL_HARD
)
283 /* this is hopeless without the right side */
284 if (!get_implied_value(expr
->right
, &right
))
286 left_rl
= _get_rl(expr
->left
, implied
);
288 max
= rl_max(left_rl
);
289 min
= rl_min(left_rl
);
291 if (implied
== RL_FUZZY
)
293 if (implied
== RL_HARD
)
295 max
= sval_type_max(get_type(expr
->left
));
296 min
= sval_type_val(get_type(expr
->left
), 0);
299 max
= sval_binop(max
, SPECIAL_RIGHTSHIFT
, right
);
300 min
= sval_binop(min
, SPECIAL_RIGHTSHIFT
, right
);
301 return alloc_rl(min
, max
);
304 static struct range_list
*handle_known_binop(struct expression
*expr
)
308 if (!get_value(expr
->left
, &left
))
310 if (!get_value(expr
->right
, &right
))
312 left
= sval_binop(left
, expr
->op
, right
);
313 return alloc_rl(left
, left
);
316 static struct range_list
*handle_binop_rl(struct expression
*expr
, int implied
)
319 struct range_list
*left_rl
, *right_rl
, *rl
;
322 rl
= handle_known_binop(expr
);
325 if (implied
== RL_EXACT
)
330 return handle_mod_rl(expr
, implied
);
332 return handle_bitwise_AND(expr
, implied
);
333 case SPECIAL_RIGHTSHIFT
:
334 return handle_right_shift(expr
, implied
);
336 return handle_subtract_rl(expr
, implied
);
338 return handle_divide_rl(expr
, implied
);
341 type
= get_type(expr
);
342 left_rl
= _get_rl(expr
->left
, implied
);
343 left_rl
= cast_rl(type
, left_rl
);
344 right_rl
= _get_rl(expr
->right
, implied
);
345 right_rl
= cast_rl(type
, right_rl
);
347 if (!left_rl
|| !right_rl
)
350 if (sval_binop_overflows(rl_min(left_rl
), expr
->op
, rl_min(right_rl
)))
352 min
= sval_binop(rl_min(left_rl
), expr
->op
, rl_min(right_rl
));
354 if (sval_binop_overflows(rl_max(left_rl
), expr
->op
, rl_max(right_rl
))) {
360 max
= sval_type_max(get_type(expr
));
363 max
= sval_binop(rl_max(left_rl
), expr
->op
, rl_max(right_rl
));
366 return alloc_rl(min
, max
);
369 static int do_comparison(struct expression
*expr
)
371 struct range_list
*left_ranges
= NULL
;
372 struct range_list
*right_ranges
= NULL
;
373 int poss_true
, poss_false
;
376 type
= get_type(expr
);
378 get_implied_rl(expr
->left
, &left_ranges
);
379 get_implied_rl(expr
->right
, &right_ranges
);
380 left_ranges
= cast_rl(type
, left_ranges
);
381 right_ranges
= cast_rl(type
, right_ranges
);
383 poss_true
= possibly_true_rl(left_ranges
, expr
->op
, right_ranges
);
384 poss_false
= possibly_false_rl(left_ranges
, expr
->op
, right_ranges
);
386 free_rl(&left_ranges
);
387 free_rl(&right_ranges
);
389 if (!poss_true
&& !poss_false
)
391 if (poss_true
&& !poss_false
)
393 if (!poss_true
&& poss_false
)
398 static struct range_list
*handle_comparison_rl(struct expression
*expr
, int implied
)
403 if (get_value(expr
->left
, &left
) && get_value(expr
->right
, &right
)) {
404 struct data_range tmp_left
, tmp_right
;
408 tmp_right
.min
= right
;
409 tmp_right
.max
= right
;
410 if (true_comparison_range(&tmp_left
, expr
->op
, &tmp_right
))
415 if (implied
== RL_EXACT
)
418 res
= do_comparison(expr
);
424 return alloc_rl(zero
, one
);
427 static struct range_list
*handle_logical_rl(struct expression
*expr
, int implied
)
433 if (implied
== RL_EXACT
) {
434 if (get_value(expr
->left
, &left
))
436 if (get_value(expr
->right
, &right
))
439 if (get_implied_value(expr
->left
, &left
))
441 if (get_implied_value(expr
->right
, &right
))
446 case SPECIAL_LOGICAL_OR
:
447 if (left_known
&& left
.value
)
449 if (right_known
&& right
.value
)
451 if (left_known
&& right_known
)
454 case SPECIAL_LOGICAL_AND
:
455 if (left_known
&& right_known
) {
456 if (left
.value
&& right
.value
)
465 if (implied
== RL_EXACT
)
468 return alloc_rl(zero
, one
);
471 static struct range_list
*handle_conditional_rl(struct expression
*expr
, int implied
)
473 struct range_list
*true_rl
, *false_rl
;
475 int final_pass_orig
= final_pass
;
477 if (known_condition_true(expr
->conditional
))
478 return _get_rl(expr
->cond_true
, implied
);
479 if (known_condition_false(expr
->conditional
))
480 return _get_rl(expr
->cond_false
, implied
);
482 if (implied
== RL_EXACT
)
485 if (implied_condition_true(expr
->conditional
))
486 return _get_rl(expr
->cond_true
, implied
);
487 if (implied_condition_false(expr
->conditional
))
488 return _get_rl(expr
->cond_false
, implied
);
491 /* this becomes a problem with deeply nested conditional statements */
495 type
= get_type(expr
);
497 __push_fake_cur_slist();
499 __split_whole_condition(expr
->conditional
);
500 true_rl
= _get_rl(expr
->cond_true
, implied
);
501 __push_true_states();
502 __use_false_states();
503 false_rl
= _get_rl(expr
->cond_false
, implied
);
504 __merge_true_states();
505 __free_fake_cur_slist();
506 final_pass
= final_pass_orig
;
508 if (!true_rl
|| !false_rl
)
510 true_rl
= cast_rl(type
, true_rl
);
511 false_rl
= cast_rl(type
, false_rl
);
513 return rl_union(true_rl
, false_rl
);
516 static int get_fuzzy_max_helper(struct expression
*expr
, sval_t
*max
)
519 struct sm_state
*tmp
;
522 if (get_hard_max(expr
, &sval
)) {
527 sm
= get_sm_state_expr(SMATCH_EXTRA
, expr
);
531 sval
= sval_type_min(estate_type(sm
->state
));
532 FOR_EACH_PTR(sm
->possible
, tmp
) {
535 new_min
= estate_min(tmp
->state
);
536 if (sval_cmp(new_min
, sval
) > 0)
538 } END_FOR_EACH_PTR(tmp
);
540 if (sval_is_min(sval
))
542 if (sval
.value
== sval_type_min(sval
.type
).value
+ 1) /* it's common to be on off */
545 *max
= sval_cast(get_type(expr
), sval
);
549 static int get_fuzzy_min_helper(struct expression
*expr
, sval_t
*min
)
552 struct sm_state
*tmp
;
555 sm
= get_sm_state_expr(SMATCH_EXTRA
, expr
);
559 if (!sval_is_min(estate_min(sm
->state
))) {
560 *min
= estate_min(sm
->state
);
564 sval
= sval_type_max(estate_type(sm
->state
));
565 FOR_EACH_PTR(sm
->possible
, tmp
) {
568 new_max
= estate_max(tmp
->state
);
569 if (sval_cmp(new_max
, sval
) < 0)
571 } END_FOR_EACH_PTR(tmp
);
573 if (sval_is_max(sval
))
575 *min
= sval_cast(get_type(expr
), sval
);
579 static int get_const_value(struct expression
*expr
, sval_t
*sval
)
584 if (expr
->type
!= EXPR_SYMBOL
|| !expr
->symbol
)
587 if (!(sym
->ctype
.modifiers
& MOD_CONST
))
589 if (get_value(sym
->initializer
, &right
)) {
590 *sval
= sval_cast(get_type(expr
), right
);
596 static struct range_list
*handle_variable(struct expression
*expr
, int implied
)
598 struct smatch_state
*state
;
599 struct range_list
*rl
;
600 sval_t sval
, min
, max
;
602 if (get_const_value(expr
, &sval
))
603 return alloc_rl(sval
, sval
);
611 state
= get_state_expr(SMATCH_EXTRA
, expr
);
612 if (!state
|| !state
->data
) {
613 if (implied
== RL_HARD
)
615 if (get_local_rl(expr
, &rl
))
619 if (implied
== RL_HARD
&& !estate_has_hard_max(state
))
621 return clone_rl(estate_rl(state
));
623 if (!get_fuzzy_min_helper(expr
, &min
))
624 min
= sval_type_min(get_type(expr
));
625 if (!get_fuzzy_max_helper(expr
, &max
))
627 /* fuzzy ranges are often inverted */
628 if (sval_cmp(min
, max
) > 0) {
633 return alloc_rl(min
, max
);
638 static sval_t
handle_sizeof(struct expression
*expr
)
643 ret
= sval_blank(expr
);
644 sym
= expr
->cast_type
;
646 sym
= evaluate_expression(expr
->cast_expression
);
648 * Expressions of restricted types will possibly get
649 * promoted - check that here
651 if (is_restricted_type(sym
)) {
652 if (sym
->bit_size
< bits_in_int
)
654 } else if (is_fouled_type(sym
)) {
658 examine_symbol_type(sym
);
660 ret
.type
= size_t_ctype
;
661 if (sym
->bit_size
<= 0) /* sizeof(void) */ {
662 if (get_real_base_type(sym
) == &void_ctype
)
667 ret
.value
= bits_to_bytes(sym
->bit_size
);
672 static struct range_list
*handle_call_rl(struct expression
*expr
, int implied
)
674 struct range_list
*rl
;
676 if (implied
== RL_EXACT
|| implied
== RL_HARD
|| implied
== RL_FUZZY
)
679 if (get_implied_return(expr
, &rl
))
681 return db_return_vals(expr
);
684 static struct range_list
*_get_rl(struct expression
*expr
, int implied
)
686 struct range_list
*rl
;
690 expr
= strip_parens(expr
);
693 type
= get_type(expr
);
695 switch (expr
->type
) {
697 sval
= sval_from_val(expr
, expr
->value
);
698 rl
= alloc_rl(sval
, sval
);
701 rl
= handle_preop_rl(expr
, implied
);
704 rl
= _get_rl(expr
->unop
, implied
);
707 case EXPR_FORCE_CAST
:
708 case EXPR_IMPLIED_CAST
:
709 rl
= _get_rl(expr
->cast_expression
, implied
);
710 rl
= cast_rl(type
, rl
);
713 rl
= handle_binop_rl(expr
, implied
);
716 rl
= handle_comparison_rl(expr
, implied
);
719 rl
= handle_logical_rl(expr
, implied
);
723 sval
= handle_sizeof(expr
);
724 rl
= alloc_rl(sval
, sval
);
727 case EXPR_CONDITIONAL
:
728 rl
= handle_conditional_rl(expr
, implied
);
731 rl
= handle_call_rl(expr
, implied
);
734 rl
= handle_variable(expr
, implied
);
739 if (type
&& implied
== RL_ABSOLUTE
)
740 return alloc_whole_rl(type
);
744 /* returns 1 if it can get a value literal or else returns 0 */
745 int get_value(struct expression
*expr
, sval_t
*sval
)
747 struct range_list
*rl
;
749 rl
= _get_rl(expr
, RL_EXACT
);
750 if (!rl_to_sval(rl
, sval
))
755 int get_implied_value(struct expression
*expr
, sval_t
*sval
)
757 struct range_list
*rl
;
759 rl
= _get_rl(expr
, RL_IMPLIED
);
760 if (!rl_to_sval(rl
, sval
))
765 int get_implied_min(struct expression
*expr
, sval_t
*sval
)
767 struct range_list
*rl
;
769 rl
= _get_rl(expr
, RL_IMPLIED
);
776 int get_implied_max(struct expression
*expr
, sval_t
*sval
)
778 struct range_list
*rl
;
780 rl
= _get_rl(expr
, RL_IMPLIED
);
787 int get_implied_rl(struct expression
*expr
, struct range_list
**rl
)
789 *rl
= _get_rl(expr
, RL_IMPLIED
);
795 int get_implied_rl_var_sym(const char *var
, struct symbol
*sym
, struct range_list
**rl
)
797 struct smatch_state
*state
;
799 state
= get_state(SMATCH_EXTRA
, var
, sym
);
800 *rl
= estate_rl(state
);
806 int get_hard_max(struct expression
*expr
, sval_t
*sval
)
808 struct range_list
*rl
;
810 rl
= _get_rl(expr
, RL_HARD
);
817 int get_fuzzy_min(struct expression
*expr
, sval_t
*sval
)
819 struct range_list
*rl
;
822 rl
= _get_rl(expr
, RL_FUZZY
);
826 if (sval_is_negative(tmp
) && sval_is_min(tmp
))
832 int get_fuzzy_max(struct expression
*expr
, sval_t
*sval
)
834 struct range_list
*rl
;
837 rl
= _get_rl(expr
, RL_FUZZY
);
841 if (max
.uvalue
> INT_MAX
- 10000)
847 int get_absolute_min(struct expression
*expr
, sval_t
*sval
)
849 struct range_list
*rl
;
852 type
= get_type(expr
);
854 type
= &llong_ctype
; // FIXME: this is wrong but places assume get type can't fail.
855 rl
= _get_rl(expr
, RL_ABSOLUTE
);
859 *sval
= sval_type_min(type
);
861 if (sval_cmp(*sval
, sval_type_min(type
)) < 0)
862 *sval
= sval_type_min(type
);
866 int get_absolute_max(struct expression
*expr
, sval_t
*sval
)
868 struct range_list
*rl
;
871 type
= get_type(expr
);
874 rl
= _get_rl(expr
, RL_ABSOLUTE
);
878 *sval
= sval_type_max(type
);
880 if (sval_cmp(sval_type_max(type
), *sval
) < 0)
881 *sval
= sval_type_max(type
);
885 int known_condition_true(struct expression
*expr
)
892 if (get_value(expr
, &tmp
) && tmp
.value
)
898 int known_condition_false(struct expression
*expr
)
906 if (expr
->type
== EXPR_CALL
) {
907 if (sym_name_is("__builtin_constant_p", expr
->fn
))
913 int implied_condition_true(struct expression
*expr
)
920 if (known_condition_true(expr
))
922 if (get_implied_value(expr
, &tmp
) && tmp
.value
)
925 if (expr
->type
== EXPR_POSTOP
)
926 return implied_condition_true(expr
->unop
);
928 if (expr
->type
== EXPR_PREOP
&& expr
->op
== SPECIAL_DECREMENT
)
929 return implied_not_equal(expr
->unop
, 1);
930 if (expr
->type
== EXPR_PREOP
&& expr
->op
== SPECIAL_INCREMENT
)
931 return implied_not_equal(expr
->unop
, -1);
933 expr
= strip_expr(expr
);
934 switch (expr
->type
) {
936 if (do_comparison(expr
) == 1)
940 if (expr
->op
== '!') {
941 if (implied_condition_false(expr
->unop
))
947 if (implied_not_equal(expr
, 0) == 1)
954 int implied_condition_false(struct expression
*expr
)
956 struct expression
*tmp
;
962 if (known_condition_false(expr
))
965 switch (expr
->type
) {
967 if (do_comparison(expr
) == 2)
970 if (expr
->op
== '!') {
971 if (implied_condition_true(expr
->unop
))
975 tmp
= strip_expr(expr
);
977 return implied_condition_false(tmp
);
980 if (get_implied_value(expr
, &sval
) && sval
.value
== 0)