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
)
230 sval_t ret
= {.type
= &int_ctype
, .value
= 123456};
235 return handle_mod(expr
, undefined
, implied
);
237 left
= _get_value(expr
->left
, &local_undef
, implied
);
239 if (implied
== IMPLIED_MIN
|| implied
== ABSOLUTE_MIN
) {
240 ret
= sval_blank(expr
->left
);
244 if (implied
!= IMPLIED_MAX
&& implied
!= ABSOLUTE_MAX
)
246 if (!get_absolute_max(expr
->left
, &left
))
249 right
= _get_value(expr
->right
, undefined
, implied
);
252 return sval_binop(left
, '&', right
);
254 case SPECIAL_RIGHTSHIFT
:
255 left
= _get_value(expr
->left
, &local_undef
, implied
);
257 if (implied
== IMPLIED_MIN
|| implied
== ABSOLUTE_MIN
) {
258 ret
= sval_blank(expr
->left
);
262 if (implied
!= IMPLIED_MAX
&& implied
!= ABSOLUTE_MAX
)
264 if (!get_absolute_max(expr
->left
, &left
))
267 right
= _get_value(expr
->right
, undefined
, implied
);
270 return sval_binop(left
, SPECIAL_RIGHTSHIFT
, right
);
273 left
= _get_value(expr
->left
, undefined
, implied
);
274 right
= _get_value(expr
->right
, undefined
, implied
);
281 return handle_divide(expr
, undefined
, implied
);
283 if (right
.value
== 0) {
287 return sval_binop(left
, '%', right
);
290 ret
= handle_subtract(expr
, undefined
, implied
);
293 ret
= sval_binop(left
, expr
->op
, right
);
298 static int do_comparison(struct expression
*expr
)
300 struct range_list
*left_ranges
= NULL
;
301 struct range_list
*right_ranges
= NULL
;
302 int poss_true
, poss_false
;
304 get_implied_range_list(expr
->left
, &left_ranges
);
305 get_implied_range_list(expr
->right
, &right_ranges
);
307 poss_true
= possibly_true_range_lists(left_ranges
, expr
->op
, right_ranges
);
308 poss_false
= possibly_false_range_lists(left_ranges
, expr
->op
, right_ranges
);
310 free_range_list(&left_ranges
);
311 free_range_list(&right_ranges
);
313 if (!poss_true
&& !poss_false
)
315 if (poss_true
&& !poss_false
)
317 if (!poss_true
&& poss_false
)
322 static sval_t
handle_comparison(struct expression
*expr
, int *undefined
, int implied
)
327 if (get_value(expr
->left
, &left
) && get_value(expr
->right
, &right
)) {
328 struct data_range tmp_left
, tmp_right
;
332 tmp_right
.min
= right
;
333 tmp_right
.max
= right
;
334 if (true_comparison_range(&tmp_left
, expr
->op
, &tmp_right
))
339 if (implied
== NOTIMPLIED
) {
344 res
= do_comparison(expr
);
350 if (implied
== IMPLIED_MIN
|| implied
== FUZZY_MIN
|| implied
== ABSOLUTE_MIN
)
352 if (implied
== IMPLIED_MAX
|| implied
== FUZZY_MAX
|| implied
== ABSOLUTE_MAX
)
359 static sval_t
handle_logical(struct expression
*expr
, int *undefined
, int implied
)
363 if ((implied
== NOTIMPLIED
&& get_value(expr
->left
, &left
) &&
364 get_value(expr
->right
, &right
)) ||
365 (implied
!= NOTIMPLIED
&& get_implied_value(expr
->left
, &left
) &&
366 get_implied_value(expr
->right
, &right
))) {
368 case SPECIAL_LOGICAL_OR
:
369 if (left
.value
|| right
.value
)
372 case SPECIAL_LOGICAL_AND
:
373 if (left
.value
&& right
.value
)
382 if (implied
== IMPLIED_MIN
|| implied
== FUZZY_MIN
|| implied
== ABSOLUTE_MIN
)
384 if (implied
== IMPLIED_MAX
|| implied
== FUZZY_MAX
|| implied
== ABSOLUTE_MAX
)
391 static sval_t
handle_conditional(struct expression
*expr
, int *undefined
, int implied
)
393 if (known_condition_true(expr
->conditional
))
394 return _get_value(expr
->cond_true
, undefined
, implied
);
395 if (known_condition_false(expr
->conditional
))
396 return _get_value(expr
->cond_false
, undefined
, implied
);
398 if (implied
== NOTIMPLIED
) {
403 if (implied_condition_true(expr
->conditional
))
404 return _get_value(expr
->cond_true
, undefined
, implied
);
405 if (implied_condition_false(expr
->conditional
))
406 return _get_value(expr
->cond_false
, undefined
, implied
);
412 static int get_implied_value_helper(struct expression
*expr
, sval_t
*sval
, int implied
)
414 struct smatch_state
*state
;
418 /* fixme: this should return the casted value */
420 expr
= strip_expr(expr
);
422 if (get_value(expr
, sval
))
425 name
= get_variable_from_expr(expr
, &sym
);
428 *sval
= sval_blank(expr
);
429 state
= get_state(SMATCH_EXTRA
, name
, sym
);
431 if (!state
|| !state
->data
)
433 if (implied
== IMPLIED
) {
434 if (estate_get_single_value(state
, sval
))
438 if (implied
== HARD_MAX
) {
439 if (estate_get_hard_max(state
, sval
))
443 if (implied
== IMPLIED_MAX
) {
444 *sval
= estate_max(state
);
445 if (sval_is_max(*sval
)) /* this means just guessing. fixme. not really */
449 *sval
= estate_min(state
);
450 if (sval_is_min(*sval
)) /* fixme */
455 static int get_fuzzy_max_helper(struct expression
*expr
, sval_t
*max
)
458 struct sm_state
*tmp
;
461 if (get_hard_max(expr
, &sval
)) {
466 sm
= get_sm_state_expr(SMATCH_EXTRA
, expr
);
470 sval
= sval_type_min(estate_type(sm
->state
));
471 FOR_EACH_PTR(sm
->possible
, tmp
) {
474 new_min
= estate_min(tmp
->state
);
475 if (sval_cmp(new_min
, sval
) > 0)
477 } END_FOR_EACH_PTR(tmp
);
479 if (sval_is_min(sval
))
482 *max
= sval_cast(get_type(expr
), sval
);
486 static int get_fuzzy_min_helper(struct expression
*expr
, sval_t
*min
)
489 struct sm_state
*tmp
;
492 if (get_implied_min(expr
, min
))
495 sm
= get_sm_state_expr(SMATCH_EXTRA
, expr
);
499 sval
= sval_type_max(estate_type(sm
->state
));
500 FOR_EACH_PTR(sm
->possible
, tmp
) {
503 new_max
= estate_max(tmp
->state
);
504 if (sval_cmp(new_max
, sval
) < 0)
506 } END_FOR_EACH_PTR(tmp
);
508 if (sval_is_max(sval
))
510 *min
= sval_cast(get_type(expr
), sval
);
514 static sval_t
_get_implied_value(struct expression
*expr
, int *undefined
, int implied
)
518 ret
= sval_blank(expr
);
525 if (!get_implied_value_helper(expr
, &ret
, implied
))
529 if (!get_absolute_min_helper(expr
, &ret
))
533 if (!get_absolute_max_helper(expr
, &ret
))
537 if (!get_fuzzy_max_helper(expr
, &ret
))
541 if (!get_fuzzy_min_helper(expr
, &ret
))
550 static int get_const_value(struct expression
*expr
, sval_t
*sval
)
555 if (expr
->type
!= EXPR_SYMBOL
|| !expr
->symbol
)
558 if (!(sym
->ctype
.modifiers
& MOD_CONST
))
560 if (get_value(sym
->initializer
, &right
)) {
561 *sval
= sval_cast(get_type(expr
), right
);
567 static sval_t
_get_value(struct expression
*expr
, int *undefined
, int implied
)
578 expr
= strip_parens(expr
);
580 switch (expr
->type
) {
582 ret
= sval_from_val(expr
, expr
->value
);
585 ret
= handle_preop(expr
, undefined
, implied
);
588 ret
= _get_value(expr
->unop
, undefined
, implied
);
591 case EXPR_FORCE_CAST
:
592 case EXPR_IMPLIED_CAST
:
593 ret
= _get_value(expr
->cast_expression
, undefined
, implied
);
594 ret
= sval_cast(get_type(expr
), ret
);
597 ret
= handle_binop(expr
, undefined
, implied
);
600 ret
= handle_comparison(expr
, undefined
, implied
);
603 ret
= handle_logical(expr
, undefined
, implied
);
607 ret
= sval_blank(expr
);
608 ret
.value
= get_expression_value_nomod(expr
);
611 if (get_const_value(expr
, &ret
)) {
614 ret
= _get_implied_value(expr
, undefined
, implied
);
617 case EXPR_CONDITIONAL
:
618 ret
= handle_conditional(expr
, undefined
, implied
);
621 ret
= _get_implied_value(expr
, undefined
, implied
);
628 /* returns 1 if it can get a value literal or else returns 0 */
629 int get_value(struct expression
*expr
, sval_t
*sval
)
634 ret
= _get_value(expr
, &undefined
, NOTIMPLIED
);
641 int get_implied_value(struct expression
*expr
, sval_t
*sval
)
646 ret
= _get_value(expr
, &undefined
, IMPLIED
);
653 int get_implied_min(struct expression
*expr
, sval_t
*sval
)
658 ret
= _get_value(expr
, &undefined
, IMPLIED_MIN
);
665 int get_implied_max(struct expression
*expr
, sval_t
*sval
)
670 ret
= _get_value(expr
, &undefined
, IMPLIED_MAX
);
677 int get_implied_range_list(struct expression
*expr
, struct range_list
**rl
)
680 struct smatch_state
*state
;
685 expr
= strip_parens(expr
);
689 state
= get_state_expr(SMATCH_EXTRA
, expr
);
691 *rl
= clone_range_list(estate_ranges(state
));
695 if (expr
->type
== EXPR_CALL
) {
696 if (get_implied_return(expr
, rl
))
698 *rl
= db_return_vals(expr
);
704 if (get_implied_value(expr
, &sval
)) {
705 add_range(rl
, sval
, sval
);
709 if (!get_implied_min(expr
, &min
))
711 if (!get_implied_max(expr
, &max
))
714 *rl
= alloc_range_list(min
, max
);
718 int get_hard_max(struct expression
*expr
, sval_t
*sval
)
723 ret
= _get_value(expr
, &undefined
, HARD_MAX
);
730 int get_fuzzy_min(struct expression
*expr
, sval_t
*sval
)
735 ret
= _get_value(expr
, &undefined
, FUZZY_MIN
);
742 int get_fuzzy_max(struct expression
*expr
, sval_t
*sval
)
747 ret
= _get_value(expr
, &undefined
, FUZZY_MAX
);
754 int get_absolute_min(struct expression
*expr
, sval_t
*sval
)
759 type
= get_type(expr
);
761 type
= &llong_ctype
; // FIXME: this is wrong but places assume get type can't fail.
762 *sval
= _get_value(expr
, &undefined
, ABSOLUTE_MIN
);
764 *sval
= sval_type_min(type
);
768 if (sval_cmp(*sval
, sval_type_min(type
)) < 0)
769 *sval
= sval_type_min(type
);
773 int get_absolute_max(struct expression
*expr
, sval_t
*sval
)
778 type
= get_type(expr
);
781 *sval
= _get_value(expr
, &undefined
, ABSOLUTE_MAX
);
783 *sval
= sval_type_max(type
);
787 if (sval_cmp(sval_type_max(type
), *sval
) < 0)
788 *sval
= sval_type_max(type
);
792 int known_condition_true(struct expression
*expr
)
799 if (get_value(expr
, &tmp
) && tmp
.value
)
805 int known_condition_false(struct expression
*expr
)
813 if (expr
->type
== EXPR_CALL
) {
814 if (sym_name_is("__builtin_constant_p", expr
->fn
))
820 int implied_condition_true(struct expression
*expr
)
827 if (known_condition_true(expr
))
829 if (get_implied_value(expr
, &tmp
) && tmp
.value
)
832 if (expr
->type
== EXPR_POSTOP
)
833 return implied_condition_true(expr
->unop
);
835 if (expr
->type
== EXPR_PREOP
&& expr
->op
== SPECIAL_DECREMENT
)
836 return implied_not_equal(expr
->unop
, 1);
837 if (expr
->type
== EXPR_PREOP
&& expr
->op
== SPECIAL_INCREMENT
)
838 return implied_not_equal(expr
->unop
, -1);
840 expr
= strip_expr(expr
);
841 switch (expr
->type
) {
843 if (do_comparison(expr
) == 1)
847 if (expr
->op
== '!') {
848 if (implied_condition_false(expr
->unop
))
854 if (implied_not_equal(expr
, 0) == 1)
861 int implied_condition_false(struct expression
*expr
)
863 struct expression
*tmp
;
869 if (known_condition_false(expr
))
872 switch (expr
->type
) {
874 if (do_comparison(expr
) == 2)
877 if (expr
->op
== '!') {
878 if (implied_condition_true(expr
->unop
))
882 tmp
= strip_expr(expr
);
884 return implied_condition_false(tmp
);
887 if (get_implied_value(expr
, &sval
) && sval
.value
== 0)