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_rl(expr
->left
, &left_ranges
);
324 get_implied_rl(expr
->right
, &right_ranges
);
326 poss_true
= possibly_true_rl(left_ranges
, expr
->op
, right_ranges
);
327 poss_false
= possibly_false_rl(left_ranges
, expr
->op
, right_ranges
);
329 free_rl(&left_ranges
);
330 free_rl(&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
)
384 if (implied
== NOTIMPLIED
) {
385 if (get_value(expr
->left
, &left
))
387 if (get_value(expr
->right
, &right
))
390 if (get_implied_value(expr
->left
, &left
))
392 if (get_implied_value(expr
->right
, &right
))
397 case SPECIAL_LOGICAL_OR
:
398 if (left_known
&& left
.value
)
400 if (right_known
&& right
.value
)
402 if (left_known
&& right_known
)
405 case SPECIAL_LOGICAL_AND
:
406 if (left_known
&& right_known
) {
407 if (left
.value
&& right
.value
)
417 if (implied
== IMPLIED_MIN
|| implied
== FUZZY_MIN
|| implied
== ABSOLUTE_MIN
)
419 if (implied
== IMPLIED_MAX
|| implied
== FUZZY_MAX
|| implied
== ABSOLUTE_MAX
)
426 static sval_t
handle_conditional(struct expression
*expr
, int *undefined
, int implied
)
428 if (known_condition_true(expr
->conditional
))
429 return _get_value(expr
->cond_true
, undefined
, implied
);
430 if (known_condition_false(expr
->conditional
))
431 return _get_value(expr
->cond_false
, undefined
, implied
);
433 if (implied
== NOTIMPLIED
) {
438 if (implied_condition_true(expr
->conditional
))
439 return _get_value(expr
->cond_true
, undefined
, implied
);
440 if (implied_condition_false(expr
->conditional
))
441 return _get_value(expr
->cond_false
, undefined
, implied
);
447 static int get_implied_value_helper(struct expression
*expr
, sval_t
*sval
, int implied
)
449 struct smatch_state
*state
;
453 /* fixme: this should return the casted value */
455 expr
= strip_expr(expr
);
457 if (get_value(expr
, sval
))
460 name
= expr_to_str_sym(expr
, &sym
);
463 *sval
= sval_blank(expr
);
464 state
= get_state(SMATCH_EXTRA
, name
, sym
);
466 if (!state
|| !state
->data
)
468 if (implied
== IMPLIED
) {
469 if (estate_get_single_value(state
, sval
))
473 if (implied
== HARD_MAX
) {
474 if (estate_get_hard_max(state
, sval
))
478 if (implied
== IMPLIED_MAX
) {
479 *sval
= estate_max(state
);
480 if (sval_is_max(*sval
)) /* this means just guessing. fixme. not really */
484 *sval
= estate_min(state
);
485 if (sval_is_min(*sval
)) /* fixme */
490 static int get_fuzzy_max_helper(struct expression
*expr
, sval_t
*max
)
493 struct sm_state
*tmp
;
496 if (get_hard_max(expr
, &sval
)) {
501 sm
= get_sm_state_expr(SMATCH_EXTRA
, expr
);
505 sval
= sval_type_min(estate_type(sm
->state
));
506 FOR_EACH_PTR(sm
->possible
, tmp
) {
509 new_min
= estate_min(tmp
->state
);
510 if (sval_cmp(new_min
, sval
) > 0)
512 } END_FOR_EACH_PTR(tmp
);
514 if (sval_is_min(sval
))
516 if (sval
.value
== sval_type_min(sval
.type
).value
+ 1) /* it's common to be on off */
519 *max
= sval_cast(get_type(expr
), sval
);
523 static int get_fuzzy_min_helper(struct expression
*expr
, sval_t
*min
)
526 struct sm_state
*tmp
;
529 if (get_implied_min(expr
, min
))
532 sm
= get_sm_state_expr(SMATCH_EXTRA
, expr
);
536 sval
= sval_type_max(estate_type(sm
->state
));
537 FOR_EACH_PTR(sm
->possible
, tmp
) {
540 new_max
= estate_max(tmp
->state
);
541 if (sval_cmp(new_max
, sval
) < 0)
543 } END_FOR_EACH_PTR(tmp
);
545 if (sval_is_max(sval
))
547 *min
= sval_cast(get_type(expr
), sval
);
551 static sval_t
_get_implied_value(struct expression
*expr
, int *undefined
, int implied
)
555 ret
= sval_blank(expr
);
562 if (!get_implied_value_helper(expr
, &ret
, implied
))
566 if (!get_absolute_min_helper(expr
, &ret
))
570 if (!get_absolute_max_helper(expr
, &ret
))
574 if (!get_fuzzy_max_helper(expr
, &ret
))
578 if (!get_fuzzy_min_helper(expr
, &ret
))
587 static int get_const_value(struct expression
*expr
, sval_t
*sval
)
592 if (expr
->type
!= EXPR_SYMBOL
|| !expr
->symbol
)
595 if (!(sym
->ctype
.modifiers
& MOD_CONST
))
597 if (get_value(sym
->initializer
, &right
)) {
598 *sval
= sval_cast(get_type(expr
), right
);
604 static sval_t
_get_value(struct expression
*expr
, int *undefined
, int implied
)
615 expr
= strip_parens(expr
);
617 switch (expr
->type
) {
619 ret
= sval_from_val(expr
, expr
->value
);
622 ret
= handle_preop(expr
, undefined
, implied
);
625 ret
= _get_value(expr
->unop
, undefined
, implied
);
628 case EXPR_FORCE_CAST
:
629 case EXPR_IMPLIED_CAST
:
630 ret
= _get_value(expr
->cast_expression
, undefined
, implied
);
631 ret
= sval_cast(get_type(expr
), ret
);
634 ret
= handle_binop(expr
, undefined
, implied
);
637 ret
= handle_comparison(expr
, undefined
, implied
);
640 ret
= handle_logical(expr
, undefined
, implied
);
644 ret
= sval_blank(expr
);
645 ret
.value
= get_expression_value_nomod(expr
);
648 if (get_const_value(expr
, &ret
)) {
651 ret
= _get_implied_value(expr
, undefined
, implied
);
654 case EXPR_CONDITIONAL
:
655 ret
= handle_conditional(expr
, undefined
, implied
);
658 ret
= _get_implied_value(expr
, undefined
, implied
);
665 /* returns 1 if it can get a value literal or else returns 0 */
666 int get_value(struct expression
*expr
, sval_t
*sval
)
671 ret
= _get_value(expr
, &undefined
, NOTIMPLIED
);
678 int get_implied_value(struct expression
*expr
, sval_t
*sval
)
683 ret
= _get_value(expr
, &undefined
, IMPLIED
);
690 int get_implied_min(struct expression
*expr
, sval_t
*sval
)
695 ret
= _get_value(expr
, &undefined
, IMPLIED_MIN
);
702 int get_implied_max(struct expression
*expr
, sval_t
*sval
)
707 ret
= _get_value(expr
, &undefined
, IMPLIED_MAX
);
714 int get_implied_rl(struct expression
*expr
, struct range_list
**rl
)
717 struct smatch_state
*state
;
722 expr
= strip_parens(expr
);
726 state
= get_state_expr(SMATCH_EXTRA
, expr
);
728 *rl
= clone_rl(estate_rl(state
));
732 if (expr
->type
== EXPR_CALL
) {
733 if (get_implied_return(expr
, rl
))
735 *rl
= db_return_vals(expr
);
741 if (get_implied_value(expr
, &sval
)) {
742 add_range(rl
, sval
, sval
);
746 if (!get_implied_min(expr
, &min
))
748 if (!get_implied_max(expr
, &max
))
751 *rl
= alloc_rl(min
, max
);
755 int get_hard_max(struct expression
*expr
, sval_t
*sval
)
760 ret
= _get_value(expr
, &undefined
, HARD_MAX
);
767 int get_fuzzy_min(struct expression
*expr
, sval_t
*sval
)
772 ret
= _get_value(expr
, &undefined
, FUZZY_MIN
);
779 int get_fuzzy_max(struct expression
*expr
, sval_t
*sval
)
784 ret
= _get_value(expr
, &undefined
, FUZZY_MAX
);
791 int get_absolute_min(struct expression
*expr
, sval_t
*sval
)
796 type
= get_type(expr
);
798 type
= &llong_ctype
; // FIXME: this is wrong but places assume get type can't fail.
799 *sval
= _get_value(expr
, &undefined
, ABSOLUTE_MIN
);
801 *sval
= sval_type_min(type
);
805 if (sval_cmp(*sval
, sval_type_min(type
)) < 0)
806 *sval
= sval_type_min(type
);
810 int get_absolute_max(struct expression
*expr
, sval_t
*sval
)
815 type
= get_type(expr
);
818 *sval
= _get_value(expr
, &undefined
, ABSOLUTE_MAX
);
820 *sval
= sval_type_max(type
);
824 if (sval_cmp(sval_type_max(type
), *sval
) < 0)
825 *sval
= sval_type_max(type
);
829 int known_condition_true(struct expression
*expr
)
836 if (get_value(expr
, &tmp
) && tmp
.value
)
842 int known_condition_false(struct expression
*expr
)
850 if (expr
->type
== EXPR_CALL
) {
851 if (sym_name_is("__builtin_constant_p", expr
->fn
))
857 int implied_condition_true(struct expression
*expr
)
864 if (known_condition_true(expr
))
866 if (get_implied_value(expr
, &tmp
) && tmp
.value
)
869 if (expr
->type
== EXPR_POSTOP
)
870 return implied_condition_true(expr
->unop
);
872 if (expr
->type
== EXPR_PREOP
&& expr
->op
== SPECIAL_DECREMENT
)
873 return implied_not_equal(expr
->unop
, 1);
874 if (expr
->type
== EXPR_PREOP
&& expr
->op
== SPECIAL_INCREMENT
)
875 return implied_not_equal(expr
->unop
, -1);
877 expr
= strip_expr(expr
);
878 switch (expr
->type
) {
880 if (do_comparison(expr
) == 1)
884 if (expr
->op
== '!') {
885 if (implied_condition_false(expr
->unop
))
891 if (implied_not_equal(expr
, 0) == 1)
898 int implied_condition_false(struct expression
*expr
)
900 struct expression
*tmp
;
906 if (known_condition_false(expr
))
909 switch (expr
->type
) {
911 if (do_comparison(expr
) == 2)
914 if (expr
->op
== '!') {
915 if (implied_condition_true(expr
->unop
))
919 tmp
= strip_expr(expr
);
921 return implied_condition_false(tmp
);
924 if (get_implied_value(expr
, &sval
) && sval
.value
== 0)