4 * Copyright (C) 2010 Dan Carpenter.
6 * Licensed under the Open Software License version 1.1
11 #include "smatch_slist.h"
12 #include "smatch_extra.h"
14 static sval_t
_get_value(struct expression
*expr
, int *undefined
, int implied
);
15 static sval_t
_get_implied_value(struct expression
*expr
, int *undefined
, int implied
);
19 static sval_t zero
= {.type
= &int_ctype
, .value
= 0};
20 static sval_t one
= {.type
= &int_ctype
, .value
= 1};
21 static sval_t bogus
= {.type
= &int_ctype
, .value
= BOGUS
};
35 static int opposite_implied(int implied
)
37 if (implied
== IMPLIED_MIN
)
39 if (implied
== IMPLIED_MAX
)
41 if (implied
== FUZZY_MIN
)
43 if (implied
== FUZZY_MAX
)
45 if (implied
== ABSOLUTE_MIN
)
47 if (implied
== ABSOLUTE_MAX
)
53 static int last_stmt_sval(struct statement
*stmt
, sval_t
*sval
)
55 struct expression
*expr
;
60 stmt
= last_ptr_list((struct ptr_list
*)stmt
->stmts
);
61 if (stmt
->type
!= STMT_EXPRESSION
)
63 expr
= stmt
->expression
;
64 if (!get_value(expr
, sval
))
69 static sval_t
handle_expression_statement(struct expression
*expr
, int *undefined
, int implied
)
71 struct statement
*stmt
;
74 stmt
= get_expression_statement(expr
);
75 if (!last_stmt_sval(stmt
, &ret
)) {
83 static sval_t
handle_ampersand(int *undefined
, int implied
)
87 ret
.type
= &ptr_ctype
;
90 if (implied
== IMPLIED_MIN
|| implied
== FUZZY_MIN
|| implied
== ABSOLUTE_MIN
)
91 return valid_ptr_min_sval
;
92 if (implied
== IMPLIED_MAX
|| implied
== FUZZY_MAX
|| implied
== ABSOLUTE_MAX
)
93 return valid_ptr_max_sval
;
99 static sval_t
handle_negate(struct expression
*expr
, int *undefined
, int implied
)
103 ret
= sval_blank(expr
->unop
);
105 if (known_condition_true(expr
->unop
)) {
110 if (implied
== NOTIMPLIED
) {
115 if (implied_condition_true(expr
->unop
)) {
119 if (implied_condition_false(expr
->unop
)) {
123 if (implied
== IMPLIED_MIN
|| implied
== FUZZY_MIN
|| implied
== ABSOLUTE_MIN
) {
127 if (implied
== IMPLIED_MAX
|| implied
== FUZZY_MAX
|| implied
== ABSOLUTE_MAX
) {
135 static sval_t
handle_preop(struct expression
*expr
, int *undefined
, int implied
)
141 ret
= handle_ampersand(undefined
, implied
);
144 ret
= handle_negate(expr
, undefined
, implied
);
147 ret
= _get_value(expr
->unop
, undefined
, implied
);
148 ret
= sval_preop(ret
, '~');
149 ret
= sval_cast(get_type(expr
->unop
), ret
);
152 ret
= _get_value(expr
->unop
, undefined
, implied
);
153 ret
= sval_preop(ret
, '-');
156 ret
= _get_implied_value(expr
, undefined
, implied
);
159 ret
= handle_expression_statement(expr
, undefined
, implied
);
163 ret
= sval_blank(expr
);
165 ret
= sval_cast(get_type(expr
), ret
);
169 static sval_t
handle_divide(struct expression
*expr
, int *undefined
, int implied
)
173 left
= _get_value(expr
->left
, undefined
, implied
);
174 right
= _get_value(expr
->right
, undefined
, opposite_implied(implied
));
176 if (right
.value
== 0) {
181 return sval_binop(left
, '/', right
);
184 static sval_t
handle_subtract(struct expression
*expr
, int *undefined
, int implied
)
188 left
= _get_value(expr
->left
, undefined
, implied
);
189 right
= _get_value(expr
->right
, undefined
, opposite_implied(implied
));
191 return sval_binop(left
, '-', right
);
194 static sval_t
handle_mod(struct expression
*expr
, int *undefined
, int implied
)
198 /* if we can't figure out the right side it's probably hopeless */
199 right
= _get_value(expr
->right
, undefined
, implied
);
200 if (*undefined
|| right
.value
== 0)
203 left
= _get_value(expr
->left
, undefined
, implied
);
205 return sval_binop(left
, '%', right
);
215 return sval_type_val(get_type(expr
->left
), 0);
220 right
= sval_cast(get_type(expr
), right
);
227 static sval_t
handle_binop(struct expression
*expr
, int *undefined
, int implied
)
231 sval_t ret
= {.type
= &int_ctype
, .value
= 123456};
236 return handle_mod(expr
, undefined
, implied
);
238 left
= _get_value(expr
->left
, &local_undef
, implied
);
240 if (implied
== IMPLIED_MIN
|| implied
== ABSOLUTE_MIN
) {
241 ret
= sval_blank(expr
->left
);
245 if (implied
!= IMPLIED_MAX
&& implied
!= ABSOLUTE_MAX
)
247 if (!get_absolute_max(expr
->left
, &left
))
250 right
= _get_value(expr
->right
, undefined
, implied
);
253 return sval_binop(left
, '&', right
);
255 case SPECIAL_RIGHTSHIFT
:
256 left
= _get_value(expr
->left
, &local_undef
, implied
);
258 if (implied
== IMPLIED_MIN
|| implied
== ABSOLUTE_MIN
) {
259 ret
= sval_blank(expr
->left
);
263 if (implied
!= IMPLIED_MAX
&& implied
!= ABSOLUTE_MAX
)
265 if (!get_absolute_max(expr
->left
, &left
))
268 right
= _get_value(expr
->right
, undefined
, implied
);
271 return sval_binop(left
, SPECIAL_RIGHTSHIFT
, right
);
274 left
= _get_value(expr
->left
, undefined
, implied
);
275 right
= _get_value(expr
->right
, undefined
, implied
);
280 type
= get_type(expr
);
281 left
= sval_cast(type
, left
);
282 right
= sval_cast(type
, right
);
287 if (sval_binop_overflows(left
, expr
->op
, right
))
288 return sval_type_max(get_type(expr
));
292 if (sval_binop_overflows(left
, expr
->op
, right
)) {
300 return handle_divide(expr
, undefined
, implied
);
302 if (right
.value
== 0) {
306 return sval_binop(left
, '%', right
);
309 ret
= handle_subtract(expr
, undefined
, implied
);
312 ret
= sval_binop(left
, expr
->op
, right
);
317 static int do_comparison(struct expression
*expr
)
319 struct range_list
*left_ranges
= NULL
;
320 struct range_list
*right_ranges
= NULL
;
321 int poss_true
, poss_false
;
323 get_implied_range_list(expr
->left
, &left_ranges
);
324 get_implied_range_list(expr
->right
, &right_ranges
);
326 poss_true
= possibly_true_range_lists(left_ranges
, expr
->op
, right_ranges
);
327 poss_false
= possibly_false_range_lists(left_ranges
, expr
->op
, right_ranges
);
329 free_range_list(&left_ranges
);
330 free_range_list(&right_ranges
);
332 if (!poss_true
&& !poss_false
)
334 if (poss_true
&& !poss_false
)
336 if (!poss_true
&& poss_false
)
341 static sval_t
handle_comparison(struct expression
*expr
, int *undefined
, int implied
)
346 if (get_value(expr
->left
, &left
) && get_value(expr
->right
, &right
)) {
347 struct data_range tmp_left
, tmp_right
;
351 tmp_right
.min
= right
;
352 tmp_right
.max
= right
;
353 if (true_comparison_range(&tmp_left
, expr
->op
, &tmp_right
))
358 if (implied
== NOTIMPLIED
) {
363 res
= do_comparison(expr
);
369 if (implied
== IMPLIED_MIN
|| implied
== FUZZY_MIN
|| implied
== ABSOLUTE_MIN
)
371 if (implied
== IMPLIED_MAX
|| implied
== FUZZY_MAX
|| implied
== ABSOLUTE_MAX
)
378 static sval_t
handle_logical(struct expression
*expr
, int *undefined
, int implied
)
382 if ((implied
== NOTIMPLIED
&& get_value(expr
->left
, &left
) &&
383 get_value(expr
->right
, &right
)) ||
384 (implied
!= NOTIMPLIED
&& get_implied_value(expr
->left
, &left
) &&
385 get_implied_value(expr
->right
, &right
))) {
387 case SPECIAL_LOGICAL_OR
:
388 if (left
.value
|| right
.value
)
391 case SPECIAL_LOGICAL_AND
:
392 if (left
.value
&& right
.value
)
401 if (implied
== IMPLIED_MIN
|| implied
== FUZZY_MIN
|| implied
== ABSOLUTE_MIN
)
403 if (implied
== IMPLIED_MAX
|| implied
== FUZZY_MAX
|| implied
== ABSOLUTE_MAX
)
410 static sval_t
handle_conditional(struct expression
*expr
, int *undefined
, int implied
)
412 if (known_condition_true(expr
->conditional
))
413 return _get_value(expr
->cond_true
, undefined
, implied
);
414 if (known_condition_false(expr
->conditional
))
415 return _get_value(expr
->cond_false
, undefined
, implied
);
417 if (implied
== NOTIMPLIED
) {
422 if (implied_condition_true(expr
->conditional
))
423 return _get_value(expr
->cond_true
, undefined
, implied
);
424 if (implied_condition_false(expr
->conditional
))
425 return _get_value(expr
->cond_false
, undefined
, implied
);
431 static int get_implied_value_helper(struct expression
*expr
, sval_t
*sval
, int implied
)
433 struct smatch_state
*state
;
437 /* fixme: this should return the casted value */
439 expr
= strip_expr(expr
);
441 if (get_value(expr
, sval
))
444 name
= get_variable_from_expr(expr
, &sym
);
447 *sval
= sval_blank(expr
);
448 state
= get_state(SMATCH_EXTRA
, name
, sym
);
450 if (!state
|| !state
->data
)
452 if (implied
== IMPLIED
) {
453 if (estate_get_single_value(state
, sval
))
457 if (implied
== HARD_MAX
) {
458 if (estate_get_hard_max(state
, sval
))
462 if (implied
== IMPLIED_MAX
) {
463 *sval
= estate_max(state
);
464 if (sval_is_max(*sval
)) /* this means just guessing. fixme. not really */
468 *sval
= estate_min(state
);
469 if (sval_is_min(*sval
)) /* fixme */
474 static int get_fuzzy_max_helper(struct expression
*expr
, sval_t
*max
)
477 struct sm_state
*tmp
;
480 if (get_hard_max(expr
, &sval
)) {
485 sm
= get_sm_state_expr(SMATCH_EXTRA
, expr
);
489 sval
= sval_type_min(estate_type(sm
->state
));
490 FOR_EACH_PTR(sm
->possible
, tmp
) {
493 new_min
= estate_min(tmp
->state
);
494 if (sval_cmp(new_min
, sval
) > 0)
496 } END_FOR_EACH_PTR(tmp
);
498 if (sval_is_min(sval
))
500 if (sval
.value
== sval_type_min(sval
.type
).value
+ 1) /* it's common to be on off */
503 *max
= sval_cast(get_type(expr
), sval
);
507 static int get_fuzzy_min_helper(struct expression
*expr
, sval_t
*min
)
510 struct sm_state
*tmp
;
513 if (get_implied_min(expr
, min
))
516 sm
= get_sm_state_expr(SMATCH_EXTRA
, expr
);
520 sval
= sval_type_max(estate_type(sm
->state
));
521 FOR_EACH_PTR(sm
->possible
, tmp
) {
524 new_max
= estate_max(tmp
->state
);
525 if (sval_cmp(new_max
, sval
) < 0)
527 } END_FOR_EACH_PTR(tmp
);
529 if (sval_is_max(sval
))
531 *min
= sval_cast(get_type(expr
), sval
);
535 static sval_t
_get_implied_value(struct expression
*expr
, int *undefined
, int implied
)
539 ret
= sval_blank(expr
);
546 if (!get_implied_value_helper(expr
, &ret
, implied
))
550 if (!get_absolute_min_helper(expr
, &ret
))
554 if (!get_absolute_max_helper(expr
, &ret
))
558 if (!get_fuzzy_max_helper(expr
, &ret
))
562 if (!get_fuzzy_min_helper(expr
, &ret
))
571 static int get_const_value(struct expression
*expr
, sval_t
*sval
)
576 if (expr
->type
!= EXPR_SYMBOL
|| !expr
->symbol
)
579 if (!(sym
->ctype
.modifiers
& MOD_CONST
))
581 if (get_value(sym
->initializer
, &right
)) {
582 *sval
= sval_cast(get_type(expr
), right
);
588 static sval_t
_get_value(struct expression
*expr
, int *undefined
, int implied
)
599 expr
= strip_parens(expr
);
601 switch (expr
->type
) {
603 ret
= sval_from_val(expr
, expr
->value
);
606 ret
= handle_preop(expr
, undefined
, implied
);
609 ret
= _get_value(expr
->unop
, undefined
, implied
);
612 case EXPR_FORCE_CAST
:
613 case EXPR_IMPLIED_CAST
:
614 ret
= _get_value(expr
->cast_expression
, undefined
, implied
);
615 ret
= sval_cast(get_type(expr
), ret
);
618 ret
= handle_binop(expr
, undefined
, implied
);
621 ret
= handle_comparison(expr
, undefined
, implied
);
624 ret
= handle_logical(expr
, undefined
, implied
);
628 ret
= sval_blank(expr
);
629 ret
.value
= get_expression_value_nomod(expr
);
632 if (get_const_value(expr
, &ret
)) {
635 ret
= _get_implied_value(expr
, undefined
, implied
);
638 case EXPR_CONDITIONAL
:
639 ret
= handle_conditional(expr
, undefined
, implied
);
642 ret
= _get_implied_value(expr
, undefined
, implied
);
649 /* returns 1 if it can get a value literal or else returns 0 */
650 int get_value(struct expression
*expr
, sval_t
*sval
)
655 ret
= _get_value(expr
, &undefined
, NOTIMPLIED
);
662 int get_implied_value(struct expression
*expr
, sval_t
*sval
)
667 ret
= _get_value(expr
, &undefined
, IMPLIED
);
674 int get_implied_min(struct expression
*expr
, sval_t
*sval
)
679 ret
= _get_value(expr
, &undefined
, IMPLIED_MIN
);
686 int get_implied_max(struct expression
*expr
, sval_t
*sval
)
691 ret
= _get_value(expr
, &undefined
, IMPLIED_MAX
);
698 int get_implied_range_list(struct expression
*expr
, struct range_list
**rl
)
701 struct smatch_state
*state
;
706 expr
= strip_parens(expr
);
710 state
= get_state_expr(SMATCH_EXTRA
, expr
);
712 *rl
= clone_range_list(estate_ranges(state
));
716 if (expr
->type
== EXPR_CALL
) {
717 if (get_implied_return(expr
, rl
))
719 *rl
= db_return_vals(expr
);
725 if (get_implied_value(expr
, &sval
)) {
726 add_range(rl
, sval
, sval
);
730 if (!get_implied_min(expr
, &min
))
732 if (!get_implied_max(expr
, &max
))
735 *rl
= alloc_range_list(min
, max
);
739 int get_hard_max(struct expression
*expr
, sval_t
*sval
)
744 ret
= _get_value(expr
, &undefined
, HARD_MAX
);
751 int get_fuzzy_min(struct expression
*expr
, sval_t
*sval
)
756 ret
= _get_value(expr
, &undefined
, FUZZY_MIN
);
763 int get_fuzzy_max(struct expression
*expr
, sval_t
*sval
)
768 ret
= _get_value(expr
, &undefined
, FUZZY_MAX
);
775 int get_absolute_min(struct expression
*expr
, sval_t
*sval
)
780 type
= get_type(expr
);
782 type
= &llong_ctype
; // FIXME: this is wrong but places assume get type can't fail.
783 *sval
= _get_value(expr
, &undefined
, ABSOLUTE_MIN
);
785 *sval
= sval_type_min(type
);
789 if (sval_cmp(*sval
, sval_type_min(type
)) < 0)
790 *sval
= sval_type_min(type
);
794 int get_absolute_max(struct expression
*expr
, sval_t
*sval
)
799 type
= get_type(expr
);
802 *sval
= _get_value(expr
, &undefined
, ABSOLUTE_MAX
);
804 *sval
= sval_type_max(type
);
808 if (sval_cmp(sval_type_max(type
), *sval
) < 0)
809 *sval
= sval_type_max(type
);
813 int known_condition_true(struct expression
*expr
)
820 if (get_value(expr
, &tmp
) && tmp
.value
)
826 int known_condition_false(struct expression
*expr
)
834 if (expr
->type
== EXPR_CALL
) {
835 if (sym_name_is("__builtin_constant_p", expr
->fn
))
841 int implied_condition_true(struct expression
*expr
)
848 if (known_condition_true(expr
))
850 if (get_implied_value(expr
, &tmp
) && tmp
.value
)
853 if (expr
->type
== EXPR_POSTOP
)
854 return implied_condition_true(expr
->unop
);
856 if (expr
->type
== EXPR_PREOP
&& expr
->op
== SPECIAL_DECREMENT
)
857 return implied_not_equal(expr
->unop
, 1);
858 if (expr
->type
== EXPR_PREOP
&& expr
->op
== SPECIAL_INCREMENT
)
859 return implied_not_equal(expr
->unop
, -1);
861 expr
= strip_expr(expr
);
862 switch (expr
->type
) {
864 if (do_comparison(expr
) == 1)
868 if (expr
->op
== '!') {
869 if (implied_condition_false(expr
->unop
))
875 if (implied_not_equal(expr
, 0) == 1)
882 int implied_condition_false(struct expression
*expr
)
884 struct expression
*tmp
;
890 if (known_condition_false(expr
))
893 switch (expr
->type
) {
895 if (do_comparison(expr
) == 2)
898 if (expr
->op
== '!') {
899 if (implied_condition_true(expr
->unop
))
903 tmp
= strip_expr(expr
);
905 return implied_condition_false(tmp
);
908 if (get_implied_value(expr
, &sval
) && sval
.value
== 0)