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 sval_t
_get_value(struct expression
*expr
, int *undefined
, int implied
);
17 static sval_t
_get_implied_value(struct expression
*expr
, int *undefined
, int implied
);
21 static sval_t zero
= {.type
= &int_ctype
, {.value
= 0} };
22 static sval_t one
= {.type
= &int_ctype
, {.value
= 1} };
23 static sval_t bogus
= {.type
= &int_ctype
, {.value
= BOGUS
} };
45 static int implied_to_rl_enum(int implied
)
66 static int opposite_implied(int implied
)
68 if (implied
== IMPLIED_MIN
)
70 if (implied
== IMPLIED_MAX
)
72 if (implied
== FUZZY_MIN
)
74 if (implied
== FUZZY_MAX
)
76 if (implied
== ABSOLUTE_MIN
)
78 if (implied
== ABSOLUTE_MAX
)
80 if (implied
== HARD_MAX
) /* we don't have a hard min. */
86 static int last_stmt_sval(struct statement
*stmt
, sval_t
*sval
)
88 struct expression
*expr
;
93 stmt
= last_ptr_list((struct ptr_list
*)stmt
->stmts
);
94 if (stmt
->type
!= STMT_EXPRESSION
)
96 expr
= stmt
->expression
;
97 if (!get_value(expr
, sval
))
102 static sval_t
handle_expression_statement(struct expression
*expr
, int *undefined
, int implied
)
104 struct statement
*stmt
;
107 stmt
= get_expression_statement(expr
);
108 if (!last_stmt_sval(stmt
, &ret
)) {
116 static sval_t
handle_ampersand(int *undefined
, int implied
)
120 ret
.type
= &ptr_ctype
;
123 if (implied
== IMPLIED_MIN
|| implied
== FUZZY_MIN
|| implied
== ABSOLUTE_MIN
)
124 return valid_ptr_min_sval
;
125 if (implied
== IMPLIED_MAX
|| implied
== FUZZY_MAX
|| implied
== ABSOLUTE_MAX
)
126 return valid_ptr_max_sval
;
132 static sval_t
handle_negate(struct expression
*expr
, int *undefined
, int implied
)
136 ret
= sval_blank(expr
->unop
);
138 if (known_condition_true(expr
->unop
)) {
143 if (implied
== EXACT
) {
148 if (implied_condition_true(expr
->unop
)) {
152 if (implied_condition_false(expr
->unop
)) {
156 if (implied
== IMPLIED_MIN
|| implied
== FUZZY_MIN
|| implied
== ABSOLUTE_MIN
) {
160 if (implied
== IMPLIED_MAX
|| implied
== FUZZY_MAX
|| implied
== ABSOLUTE_MAX
) {
168 static sval_t
handle_preop(struct expression
*expr
, int *undefined
, int implied
)
174 ret
= handle_ampersand(undefined
, implied
);
177 ret
= handle_negate(expr
, undefined
, implied
);
180 ret
= _get_value(expr
->unop
, undefined
, implied
);
181 ret
= sval_preop(ret
, '~');
182 ret
= sval_cast(get_type(expr
->unop
), ret
);
185 ret
= _get_value(expr
->unop
, undefined
, implied
);
186 ret
= sval_preop(ret
, '-');
189 ret
= _get_implied_value(expr
, undefined
, implied
);
192 ret
= handle_expression_statement(expr
, undefined
, implied
);
196 ret
= sval_blank(expr
);
198 ret
= sval_cast(get_type(expr
), ret
);
202 static sval_t
handle_divide(struct expression
*expr
, int *undefined
, int implied
)
206 left
= _get_value(expr
->left
, undefined
, implied
);
207 right
= _get_value(expr
->right
, undefined
, opposite_implied(implied
));
209 if (right
.value
== 0) {
214 return sval_binop(left
, '/', right
);
217 static sval_t
handle_subtract(struct expression
*expr
, int *undefined
, int implied
)
220 sval_t left
, right
, ret
;
221 int left_undefined
= 0;
222 int right_undefined
= 0;
223 int known_but_negative
= 0;
226 left
= _get_value(expr
->left
, &left_undefined
, implied
);
227 right
= _get_value(expr
->right
, &right_undefined
, opposite_implied(implied
));
229 if (!left_undefined
&& !right_undefined
) {
230 ret
= sval_binop(left
, '-', right
);
231 if (sval_is_negative(ret
))
232 known_but_negative
= 1;
234 return ret
; /* best case scenario */
237 comparison
= get_comparison(expr
->left
, expr
->right
);
241 type
= get_type(expr
);
243 switch (comparison
) {
245 case SPECIAL_UNSIGNED_GT
:
250 return sval_type_val(type
, 1);
254 return _get_value(expr
->left
, undefined
, implied
);
258 case SPECIAL_UNSIGNED_GTE
:
263 return sval_type_val(type
, 0);
267 return _get_value(expr
->left
, undefined
, implied
);
272 if (known_but_negative
)
280 static sval_t
handle_mod(struct expression
*expr
, int *undefined
, int implied
)
284 /* if we can't figure out the right side it's probably hopeless */
285 right
= _get_value(expr
->right
, undefined
, implied
);
286 if (*undefined
|| right
.value
== 0) {
294 left
= _get_value(expr
->left
, undefined
, implied
);
296 return sval_binop(left
, '%', right
);
302 return sval_type_val(get_type(expr
), 0);
307 right
= sval_cast(get_type(expr
), right
);
314 static sval_t
handle_binop(struct expression
*expr
, int *undefined
, int implied
)
318 sval_t ret
= {.type
= &int_ctype
, {.value
= 123456} };
323 return handle_mod(expr
, undefined
, implied
);
325 if (implied
== HARD_MAX
) {
329 left
= _get_value(expr
->left
, &local_undef
, implied
);
331 if (implied
== IMPLIED_MIN
|| implied
== ABSOLUTE_MIN
) {
332 ret
= sval_blank(expr
->left
);
336 if (implied
!= IMPLIED_MAX
&& implied
!= ABSOLUTE_MAX
)
338 if (!get_absolute_max(expr
->left
, &left
))
341 right
= _get_value(expr
->right
, undefined
, implied
);
344 return sval_binop(left
, '&', right
);
346 case SPECIAL_RIGHTSHIFT
:
347 if (implied
== HARD_MAX
) {
351 left
= _get_value(expr
->left
, &local_undef
, implied
);
353 if (implied
== IMPLIED_MIN
|| implied
== ABSOLUTE_MIN
) {
354 ret
= sval_blank(expr
->left
);
358 if (implied
!= IMPLIED_MAX
&& implied
!= ABSOLUTE_MAX
)
360 if (!get_absolute_max(expr
->left
, &left
))
363 right
= _get_value(expr
->right
, undefined
, implied
);
366 return sval_binop(left
, SPECIAL_RIGHTSHIFT
, right
);
368 return handle_subtract(expr
, undefined
, implied
);
371 left
= _get_value(expr
->left
, undefined
, implied
);
372 right
= _get_value(expr
->right
, undefined
, implied
);
377 type
= get_type(expr
);
378 left
= sval_cast(type
, left
);
379 right
= sval_cast(type
, right
);
384 if (sval_binop_overflows(left
, expr
->op
, right
))
385 return sval_type_max(get_type(expr
));
389 if (sval_binop_overflows(left
, expr
->op
, right
)) {
397 return handle_divide(expr
, undefined
, implied
);
399 if (right
.value
== 0) {
403 return sval_binop(left
, '%', right
);
406 ret
= sval_binop(left
, expr
->op
, right
);
411 static int do_comparison(struct expression
*expr
)
413 struct range_list
*left_ranges
= NULL
;
414 struct range_list
*right_ranges
= NULL
;
415 int poss_true
, poss_false
;
418 type
= get_type(expr
);
420 get_implied_rl(expr
->left
, &left_ranges
);
421 get_implied_rl(expr
->right
, &right_ranges
);
422 left_ranges
= cast_rl(type
, left_ranges
);
423 right_ranges
= cast_rl(type
, right_ranges
);
425 poss_true
= possibly_true_rl(left_ranges
, expr
->op
, right_ranges
);
426 poss_false
= possibly_false_rl(left_ranges
, expr
->op
, right_ranges
);
428 free_rl(&left_ranges
);
429 free_rl(&right_ranges
);
431 if (!poss_true
&& !poss_false
)
433 if (poss_true
&& !poss_false
)
435 if (!poss_true
&& poss_false
)
440 static sval_t
handle_comparison(struct expression
*expr
, int *undefined
, int implied
)
445 if (get_value(expr
->left
, &left
) && get_value(expr
->right
, &right
)) {
446 struct data_range tmp_left
, tmp_right
;
450 tmp_right
.min
= right
;
451 tmp_right
.max
= right
;
452 if (true_comparison_range(&tmp_left
, expr
->op
, &tmp_right
))
457 if (implied
== EXACT
) {
462 res
= do_comparison(expr
);
468 if (implied
== IMPLIED_MIN
|| implied
== FUZZY_MIN
|| implied
== ABSOLUTE_MIN
)
470 if (implied
== IMPLIED_MAX
|| implied
== FUZZY_MAX
|| implied
== ABSOLUTE_MAX
)
477 static sval_t
handle_logical(struct expression
*expr
, int *undefined
, int implied
)
483 if (implied
== EXACT
) {
484 if (get_value(expr
->left
, &left
))
486 if (get_value(expr
->right
, &right
))
489 if (get_implied_value(expr
->left
, &left
))
491 if (get_implied_value(expr
->right
, &right
))
496 case SPECIAL_LOGICAL_OR
:
497 if (left_known
&& left
.value
)
499 if (right_known
&& right
.value
)
501 if (left_known
&& right_known
)
504 case SPECIAL_LOGICAL_AND
:
505 if (left_known
&& right_known
) {
506 if (left
.value
&& right
.value
)
516 if (implied
== IMPLIED_MIN
|| implied
== FUZZY_MIN
|| implied
== ABSOLUTE_MIN
)
518 if (implied
== IMPLIED_MAX
|| implied
== FUZZY_MAX
|| implied
== ABSOLUTE_MAX
)
525 static sval_t
handle_conditional(struct expression
*expr
, int *undefined
, int implied
)
527 if (known_condition_true(expr
->conditional
))
528 return _get_value(expr
->cond_true
, undefined
, implied
);
529 if (known_condition_false(expr
->conditional
))
530 return _get_value(expr
->cond_false
, undefined
, implied
);
532 if (implied
== EXACT
) {
537 if (implied_condition_true(expr
->conditional
))
538 return _get_value(expr
->cond_true
, undefined
, implied
);
539 if (implied_condition_false(expr
->conditional
))
540 return _get_value(expr
->cond_false
, undefined
, implied
);
546 static int get_local_value(struct expression
*expr
, sval_t
*sval
, int implied
)
555 return get_local_min_helper(expr
, sval
);
560 return get_local_max_helper(expr
, sval
);
565 static int get_implied_value_helper(struct expression
*expr
, sval_t
*sval
, int implied
)
567 struct smatch_state
*state
;
571 /* fixme: this should return the casted value */
573 expr
= strip_expr(expr
);
575 if (get_value(expr
, sval
))
578 name
= expr_to_var_sym(expr
, &sym
);
581 *sval
= sval_blank(expr
);
582 state
= get_state(SMATCH_EXTRA
, name
, sym
);
584 if (!state
|| !state
->data
)
585 return get_local_value(expr
, sval
, implied
);
586 if (implied
== IMPLIED
) {
587 if (estate_get_single_value(state
, sval
))
591 if (implied
== HARD_MAX
) {
592 if (estate_get_hard_max(state
, sval
))
596 if (implied
== IMPLIED_MAX
|| implied
== ABSOLUTE_MAX
) {
597 *sval
= estate_max(state
);
600 *sval
= estate_min(state
);
604 static int get_fuzzy_max_helper(struct expression
*expr
, sval_t
*max
)
607 struct sm_state
*tmp
;
610 if (get_hard_max(expr
, &sval
)) {
615 sm
= get_sm_state_expr(SMATCH_EXTRA
, expr
);
619 sval
= sval_type_min(estate_type(sm
->state
));
620 FOR_EACH_PTR(sm
->possible
, tmp
) {
623 new_min
= estate_min(tmp
->state
);
624 if (sval_cmp(new_min
, sval
) > 0)
626 } END_FOR_EACH_PTR(tmp
);
628 if (sval_is_min(sval
))
630 if (sval
.value
== sval_type_min(sval
.type
).value
+ 1) /* it's common to be on off */
633 *max
= sval_cast(get_type(expr
), sval
);
637 static int get_fuzzy_min_helper(struct expression
*expr
, sval_t
*min
)
640 struct sm_state
*tmp
;
643 sm
= get_sm_state_expr(SMATCH_EXTRA
, expr
);
647 if (!sval_is_min(estate_min(sm
->state
))) {
648 *min
= estate_min(sm
->state
);
652 sval
= sval_type_max(estate_type(sm
->state
));
653 FOR_EACH_PTR(sm
->possible
, tmp
) {
656 new_max
= estate_max(tmp
->state
);
657 if (sval_cmp(new_max
, sval
) < 0)
659 } END_FOR_EACH_PTR(tmp
);
661 if (sval_is_max(sval
))
663 *min
= sval_cast(get_type(expr
), sval
);
667 static sval_t
_get_implied_value(struct expression
*expr
, int *undefined
, int implied
)
671 ret
= sval_blank(expr
);
680 if (!get_implied_value_helper(expr
, &ret
, implied
))
684 if (!get_fuzzy_max_helper(expr
, &ret
))
688 if (!get_fuzzy_min_helper(expr
, &ret
))
697 static int get_const_value(struct expression
*expr
, sval_t
*sval
)
702 if (expr
->type
!= EXPR_SYMBOL
|| !expr
->symbol
)
705 if (!(sym
->ctype
.modifiers
& MOD_CONST
))
707 if (get_value(sym
->initializer
, &right
)) {
708 *sval
= sval_cast(get_type(expr
), right
);
714 static sval_t
handle_sizeof(struct expression
*expr
)
719 ret
= sval_blank(expr
);
720 sym
= expr
->cast_type
;
722 sym
= evaluate_expression(expr
->cast_expression
);
724 * Expressions of restricted types will possibly get
725 * promoted - check that here
727 if (is_restricted_type(sym
)) {
728 if (sym
->bit_size
< bits_in_int
)
730 } else if (is_fouled_type(sym
)) {
734 examine_symbol_type(sym
);
736 ret
.type
= size_t_ctype
;
737 if (sym
->bit_size
<= 0) /* sizeof(void) */ {
738 if (get_real_base_type(sym
) == &void_ctype
)
743 ret
.value
= bits_to_bytes(sym
->bit_size
);
748 static sval_t
handle_call(struct expression
*expr
, int *undefined
, int implied
)
750 struct range_list
*rl
;
752 if (!get_implied_rl(expr
, &rl
)) {
759 if (sval_cmp(rl_min(rl
), rl_max(rl
)) == 0)
778 static struct range_list
*_get_rl(struct expression
*expr
, int implied
)
780 struct range_list
*rl
;
785 expr
= strip_parens(expr
);
788 type
= get_type(expr
);
791 switch (expr
->type
) {
793 sval
= sval_from_val(expr
, expr
->value
);
796 sval
= handle_preop(expr
, &undefined
, implied
);
799 sval
= _get_value(expr
->unop
, &undefined
, implied
);
802 case EXPR_FORCE_CAST
:
803 case EXPR_IMPLIED_CAST
:
804 sval
= _get_value(expr
->cast_expression
, &undefined
, implied
);
805 sval
= sval_cast(type
, sval
);
808 sval
= handle_binop(expr
, &undefined
, implied
);
811 sval
= handle_comparison(expr
, &undefined
, implied
);
814 sval
= handle_logical(expr
, &undefined
, implied
);
818 sval
= handle_sizeof(expr
);
821 if (get_const_value(expr
, &sval
)) {
824 sval
= _get_implied_value(expr
, &undefined
, implied
);
827 case EXPR_CONDITIONAL
:
828 sval
= handle_conditional(expr
, &undefined
, implied
);
831 sval
= handle_call(expr
, &undefined
, implied
);
834 sval
= _get_implied_value(expr
, &undefined
, implied
);
837 if (undefined
&& type
&&
838 (implied
== ABSOLUTE_MAX
|| implied
== ABSOLUTE_MIN
))
839 return alloc_whole_rl(type
);
842 rl
= alloc_rl(sval
, sval
);
846 static sval_t
_get_value(struct expression
*expr
, int *undefined
, int implied
)
858 expr
= strip_parens(expr
);
859 type
= get_type(expr
);
861 switch (expr
->type
) {
863 ret
= sval_from_val(expr
, expr
->value
);
866 ret
= handle_preop(expr
, undefined
, implied
);
869 ret
= _get_value(expr
->unop
, undefined
, implied
);
872 case EXPR_FORCE_CAST
:
873 case EXPR_IMPLIED_CAST
:
874 ret
= _get_value(expr
->cast_expression
, undefined
, implied
);
875 ret
= sval_cast(type
, ret
);
878 ret
= handle_binop(expr
, undefined
, implied
);
881 ret
= handle_comparison(expr
, undefined
, implied
);
884 ret
= handle_logical(expr
, undefined
, implied
);
888 ret
= handle_sizeof(expr
);
891 if (get_const_value(expr
, &ret
)) {
894 ret
= _get_implied_value(expr
, undefined
, implied
);
897 case EXPR_CONDITIONAL
:
898 ret
= handle_conditional(expr
, undefined
, implied
);
901 ret
= handle_call(expr
, undefined
, implied
);
904 ret
= _get_implied_value(expr
, undefined
, implied
);
912 /* returns 1 if it can get a value literal or else returns 0 */
913 int get_value(struct expression
*expr
, sval_t
*sval
)
915 struct range_list
*rl
;
917 rl
= _get_rl(expr
, EXACT
);
918 if (!rl_to_sval(rl
, sval
))
923 int get_implied_value(struct expression
*expr
, sval_t
*sval
)
925 struct range_list
*rl
;
927 rl
= _get_rl(expr
, IMPLIED
);
928 if (!rl_to_sval(rl
, sval
))
933 int get_implied_min(struct expression
*expr
, sval_t
*sval
)
935 struct range_list
*rl
;
937 rl
= _get_rl(expr
, IMPLIED_MIN
);
944 int get_implied_max(struct expression
*expr
, sval_t
*sval
)
946 struct range_list
*rl
;
948 rl
= _get_rl(expr
, IMPLIED_MAX
);
955 int get_implied_rl(struct expression
*expr
, struct range_list
**rl
)
958 struct smatch_state
*state
;
965 expr
= strip_parens(expr
);
969 state
= get_state_expr(SMATCH_EXTRA
, expr
);
971 *rl
= clone_rl(estate_rl(state
));
975 if (expr
->type
== EXPR_CALL
) {
976 if (get_implied_return(expr
, rl
))
978 *rl
= db_return_vals(expr
);
984 if (get_implied_value(expr
, &sval
)) {
985 add_range(rl
, sval
, sval
);
989 if (get_local_rl(expr
, rl
))
992 min_known
= get_implied_min(expr
, &min
);
993 max_known
= get_implied_max(expr
, &max
);
994 if (!min_known
&& !max_known
)
997 get_absolute_min(expr
, &min
);
999 get_absolute_max(expr
, &max
);
1001 *rl
= alloc_rl(min
, max
);
1005 int get_hard_max(struct expression
*expr
, sval_t
*sval
)
1007 struct range_list
*rl
;
1009 rl
= _get_rl(expr
, HARD_MAX
);
1016 int get_fuzzy_min(struct expression
*expr
, sval_t
*sval
)
1018 struct range_list
*rl
;
1020 rl
= _get_rl(expr
, FUZZY_MIN
);
1027 int get_fuzzy_max(struct expression
*expr
, sval_t
*sval
)
1029 struct range_list
*rl
;
1032 rl
= _get_rl(expr
, FUZZY_MAX
);
1036 if (max
.uvalue
> INT_MAX
- 10000)
1042 int get_absolute_min(struct expression
*expr
, sval_t
*sval
)
1044 struct range_list
*rl
;
1045 struct symbol
*type
;
1047 type
= get_type(expr
);
1049 type
= &llong_ctype
; // FIXME: this is wrong but places assume get type can't fail.
1050 rl
= _get_rl(expr
, ABSOLUTE_MIN
);
1054 *sval
= sval_type_min(type
);
1056 if (sval_cmp(*sval
, sval_type_min(type
)) < 0)
1057 *sval
= sval_type_min(type
);
1061 int get_absolute_max(struct expression
*expr
, sval_t
*sval
)
1063 struct range_list
*rl
;
1064 struct symbol
*type
;
1066 type
= get_type(expr
);
1068 type
= &llong_ctype
;
1069 rl
= _get_rl(expr
, ABSOLUTE_MAX
);
1073 *sval
= sval_type_max(type
);
1075 if (sval_cmp(sval_type_max(type
), *sval
) < 0)
1076 *sval
= sval_type_max(type
);
1080 int known_condition_true(struct expression
*expr
)
1087 if (get_value(expr
, &tmp
) && tmp
.value
)
1093 int known_condition_false(struct expression
*expr
)
1101 if (expr
->type
== EXPR_CALL
) {
1102 if (sym_name_is("__builtin_constant_p", expr
->fn
))
1108 int implied_condition_true(struct expression
*expr
)
1115 if (known_condition_true(expr
))
1117 if (get_implied_value(expr
, &tmp
) && tmp
.value
)
1120 if (expr
->type
== EXPR_POSTOP
)
1121 return implied_condition_true(expr
->unop
);
1123 if (expr
->type
== EXPR_PREOP
&& expr
->op
== SPECIAL_DECREMENT
)
1124 return implied_not_equal(expr
->unop
, 1);
1125 if (expr
->type
== EXPR_PREOP
&& expr
->op
== SPECIAL_INCREMENT
)
1126 return implied_not_equal(expr
->unop
, -1);
1128 expr
= strip_expr(expr
);
1129 switch (expr
->type
) {
1131 if (do_comparison(expr
) == 1)
1135 if (expr
->op
== '!') {
1136 if (implied_condition_false(expr
->unop
))
1142 if (implied_not_equal(expr
, 0) == 1)
1149 int implied_condition_false(struct expression
*expr
)
1151 struct expression
*tmp
;
1157 if (known_condition_false(expr
))
1160 switch (expr
->type
) {
1162 if (do_comparison(expr
) == 2)
1165 if (expr
->op
== '!') {
1166 if (implied_condition_true(expr
->unop
))
1170 tmp
= strip_expr(expr
);
1172 return implied_condition_false(tmp
);
1175 if (get_implied_value(expr
, &sval
) && sval
.value
== 0)