2 * smatch/smatch_comparison.c
4 * Copyright (C) 2012 Oracle.
6 * Licensed under the Open Software License version 1.1
11 * The point here is to store the relationships between two variables.
13 * To do that we create a state with the two variables in alphabetical order:
14 * ->name = "x vs y" and the state would be "<". On the false path the state
17 * Part of the trick of it is that if x or y is modified then we need to reset
18 * the state. We need to keep a list of all the states which depend on x and
19 * all the states which depend on y. The link_id code handles this.
21 * Future work: If we know that x is greater than y and y is greater than z
22 * then we know that x is greater than z.
26 #include "smatch_extra.h"
27 #include "smatch_slist.h"
29 static int compare_id
;
39 ALLOCATOR(compare_data
, "compare data");
41 int var_sym_eq(const char *a
, struct symbol
*a_sym
, const char *b
, struct symbol
*b_sym
)
45 if (strcmp(a
, b
) == 0)
50 static struct smatch_state
*alloc_compare_state(
51 const char *var1
, struct symbol
*sym1
,
53 const char *var2
, struct symbol
*sym2
)
55 struct smatch_state
*state
;
56 struct compare_data
*data
;
58 state
= __alloc_smatch_state(0);
59 state
->name
= alloc_sname(show_special(comparison
));
60 data
= __alloc_compare_data(0);
61 data
->var1
= alloc_sname(var1
);
63 data
->comparison
= comparison
;
64 data
->var2
= alloc_sname(var2
);
70 static int state_to_comparison(struct smatch_state
*state
)
72 if (!state
|| !state
->data
)
74 return ((struct compare_data
*)state
->data
)->comparison
;
78 * flip_op() reverses the op left and right. So "x >= y" becomes "y <= x".
80 static int flip_op(int op
)
87 case SPECIAL_UNSIGNED_LT
:
88 return SPECIAL_UNSIGNED_GT
;
91 case SPECIAL_UNSIGNED_LTE
:
92 return SPECIAL_UNSIGNED_GTE
;
95 case SPECIAL_NOTEQUAL
:
96 return SPECIAL_NOTEQUAL
;
99 case SPECIAL_UNSIGNED_GTE
:
100 return SPECIAL_UNSIGNED_LTE
;
103 case SPECIAL_UNSIGNED_GT
:
104 return SPECIAL_UNSIGNED_LT
;
106 sm_msg("internal smatch bug. unhandled comparison %d", op
);
111 static int falsify_op(int op
)
118 case SPECIAL_UNSIGNED_LT
:
119 return SPECIAL_UNSIGNED_GTE
;
122 case SPECIAL_UNSIGNED_LTE
:
123 return SPECIAL_UNSIGNED_GT
;
125 return SPECIAL_NOTEQUAL
;
126 case SPECIAL_NOTEQUAL
:
127 return SPECIAL_EQUAL
;
130 case SPECIAL_UNSIGNED_GTE
:
131 return SPECIAL_UNSIGNED_LT
;
134 case SPECIAL_UNSIGNED_GT
:
135 return SPECIAL_UNSIGNED_LTE
;
137 sm_msg("internal smatch bug. unhandled comparison %d", op
);
142 static int rl_comparison(struct range_list
*left_rl
, struct range_list
*right_rl
)
144 sval_t left_min
, left_max
, right_min
, right_max
;
146 if (!left_rl
|| !right_rl
)
149 left_min
= rl_min(left_rl
);
150 left_max
= rl_max(left_rl
);
151 right_min
= rl_min(right_rl
);
152 right_max
= rl_max(right_rl
);
154 if (left_min
.value
== left_max
.value
&&
155 right_min
.value
== right_max
.value
&&
156 left_min
.value
== right_min
.value
)
157 return SPECIAL_EQUAL
;
159 if (sval_cmp(left_max
, right_min
) < 0)
161 if (sval_cmp(left_max
, right_min
) == 0)
163 if (sval_cmp(left_min
, right_max
) > 0)
165 if (sval_cmp(left_min
, right_max
) == 0)
171 static struct range_list
*get_orig_rl(struct symbol
*sym
)
173 struct smatch_state
*state
;
175 if (!sym
|| !sym
->ident
)
177 state
= get_orig_estate(sym
->ident
->name
, sym
);
178 return estate_rl(state
);
181 static struct smatch_state
*unmatched_comparison(struct sm_state
*sm
)
183 struct compare_data
*data
= sm
->state
->data
;
184 struct range_list
*left_rl
, *right_rl
;
190 if (strstr(data
->var1
, " orig"))
191 left_rl
= get_orig_rl(data
->sym1
);
192 else if (!get_implied_rl_var_sym(data
->var1
, data
->sym1
, &left_rl
))
194 if (strstr(data
->var2
, " orig"))
195 right_rl
= get_orig_rl(data
->sym2
);
196 else if (!get_implied_rl_var_sym(data
->var2
, data
->sym2
, &right_rl
))
199 op
= rl_comparison(left_rl
, right_rl
);
201 return alloc_compare_state(data
->var1
, data
->sym1
, op
, data
->var2
, data
->sym2
);
206 /* remove_unsigned_from_comparison() is obviously a hack. */
207 static int remove_unsigned_from_comparison(int op
)
210 case SPECIAL_UNSIGNED_LT
:
212 case SPECIAL_UNSIGNED_LTE
:
214 case SPECIAL_UNSIGNED_GTE
:
216 case SPECIAL_UNSIGNED_GT
:
223 static int merge_comparisons(int one
, int two
)
227 one
= remove_unsigned_from_comparison(one
);
228 two
= remove_unsigned_from_comparison(two
);
275 return SPECIAL_NOTEQUAL
;
285 static struct smatch_state
*merge_compare_states(struct smatch_state
*s1
, struct smatch_state
*s2
)
287 struct compare_data
*data
= s1
->data
;
290 op
= merge_comparisons(state_to_comparison(s1
), state_to_comparison(s2
));
292 return alloc_compare_state(data
->var1
, data
->sym1
, op
, data
->var2
, data
->sym2
);
296 struct smatch_state
*alloc_link_state(struct string_list
*links
)
298 struct smatch_state
*state
;
299 static char buf
[256];
303 state
= __alloc_smatch_state(0);
306 FOR_EACH_PTR(links
, tmp
) {
308 snprintf(buf
, sizeof(buf
), "%s", tmp
);
310 snprintf(buf
, sizeof(buf
), "%s, %s", buf
, tmp
);
311 } END_FOR_EACH_PTR(tmp
);
313 state
->name
= alloc_sname(buf
);
318 static void save_start_states(struct statement
*stmt
)
320 struct symbol
*param
;
322 char state_name
[128];
323 struct smatch_state
*state
;
324 struct string_list
*links
;
327 FOR_EACH_PTR(cur_func_sym
->ctype
.base_type
->arguments
, param
) {
330 snprintf(orig
, sizeof(orig
), "%s orig", param
->ident
->name
);
331 snprintf(state_name
, sizeof(state_name
), "%s vs %s", param
->ident
->name
, orig
);
332 state
= alloc_compare_state(param
->ident
->name
, param
, SPECIAL_EQUAL
, alloc_sname(orig
), param
);
333 set_state(compare_id
, state_name
, NULL
, state
);
335 link
= alloc_sname(state_name
);
337 insert_string(&links
, link
);
338 state
= alloc_link_state(links
);
339 set_state(link_id
, param
->ident
->name
, param
, state
);
340 } END_FOR_EACH_PTR(param
);
343 static struct smatch_state
*merge_links(struct smatch_state
*s1
, struct smatch_state
*s2
)
345 struct smatch_state
*ret
;
346 struct string_list
*links
;
348 links
= combine_string_lists(s1
->data
, s2
->data
);
349 ret
= alloc_link_state(links
);
353 static void save_link_var_sym(const char *var
, struct symbol
*sym
, char *link
)
355 struct smatch_state
*old_state
, *new_state
;
356 struct string_list
*links
;
359 old_state
= get_state(link_id
, var
, sym
);
361 links
= clone_str_list(old_state
->data
);
365 new = alloc_sname(link
);
366 insert_string(&links
, new);
368 new_state
= alloc_link_state(links
);
369 set_state(link_id
, var
, sym
, new_state
);
372 static void save_link(struct expression
*expr
, char *link
)
377 var
= expr_to_var_sym(expr
, &sym
);
381 save_link_var_sym(var
, sym
, link
);
386 static void match_inc(struct sm_state
*sm
)
388 struct string_list
*links
;
389 struct smatch_state
*state
;
392 links
= sm
->state
->data
;
394 FOR_EACH_PTR(links
, tmp
) {
395 state
= get_state(compare_id
, tmp
, NULL
);
397 switch (state_to_comparison(state
)) {
400 case SPECIAL_UNSIGNED_GTE
:
402 case SPECIAL_UNSIGNED_GT
: {
403 struct compare_data
*data
= state
->data
;
404 struct smatch_state
*new;
406 new = alloc_compare_state(data
->var1
, data
->sym1
, '>', data
->var2
, data
->sym2
);
407 set_state(compare_id
, tmp
, NULL
, new);
411 set_state(compare_id
, tmp
, NULL
, &undefined
);
413 } END_FOR_EACH_PTR(tmp
);
416 static void match_dec(struct sm_state
*sm
)
418 struct string_list
*links
;
419 struct smatch_state
*state
;
422 links
= sm
->state
->data
;
424 FOR_EACH_PTR(links
, tmp
) {
425 state
= get_state(compare_id
, tmp
, NULL
);
427 switch (state_to_comparison(state
)) {
430 case SPECIAL_UNSIGNED_LTE
:
432 case SPECIAL_UNSIGNED_LT
: {
433 struct compare_data
*data
= state
->data
;
434 struct smatch_state
*new;
436 new = alloc_compare_state(data
->var1
, data
->sym1
, '<', data
->var2
, data
->sym2
);
437 set_state(compare_id
, tmp
, NULL
, new);
441 set_state(compare_id
, tmp
, NULL
, &undefined
);
443 } END_FOR_EACH_PTR(tmp
);
446 static int match_inc_dec(struct sm_state
*sm
, struct expression
*mod_expr
)
450 if (mod_expr
->type
!= EXPR_PREOP
&& mod_expr
->type
!= EXPR_POSTOP
)
453 if (mod_expr
->op
== SPECIAL_INCREMENT
) {
457 if (mod_expr
->op
== SPECIAL_DECREMENT
) {
464 static void match_modify(struct sm_state
*sm
, struct expression
*mod_expr
)
466 struct string_list
*links
;
469 if (match_inc_dec(sm
, mod_expr
))
472 links
= sm
->state
->data
;
474 FOR_EACH_PTR(links
, tmp
) {
475 set_state(compare_id
, tmp
, NULL
, &undefined
);
476 } END_FOR_EACH_PTR(tmp
);
477 set_state(link_id
, sm
->name
, sm
->sym
, &undefined
);
480 static void match_compare(struct expression
*expr
)
484 struct symbol
*left_sym
, *right_sym
;
486 struct smatch_state
*true_state
, *false_state
;
487 char state_name
[256];
489 if (expr
->type
!= EXPR_COMPARE
)
491 left
= expr_to_var_sym(expr
->left
, &left_sym
);
492 if (!left
|| !left_sym
)
494 right
= expr_to_var_sym(expr
->right
, &right_sym
);
495 if (!right
|| !right_sym
)
498 if (strcmp(left
, right
) > 0) {
499 struct symbol
*tmp_sym
= left_sym
;
500 char *tmp_name
= left
;
503 left_sym
= right_sym
;
506 op
= flip_op(expr
->op
);
510 false_op
= falsify_op(op
);
511 snprintf(state_name
, sizeof(state_name
), "%s vs %s", left
, right
);
512 true_state
= alloc_compare_state(left
, left_sym
, op
, right
, right_sym
);
513 false_state
= alloc_compare_state(left
, left_sym
, false_op
, right
, right_sym
);
515 set_true_false_states(compare_id
, state_name
, NULL
, true_state
, false_state
);
516 save_link(expr
->left
, state_name
);
517 save_link(expr
->right
, state_name
);
523 static void add_comparison_var_sym(const char *left_name
, struct symbol
*left_sym
, int comparison
, const char *right_name
, struct symbol
*right_sym
)
525 struct smatch_state
*state
;
526 char state_name
[256];
528 if (strcmp(left_name
, right_name
) > 0) {
529 struct symbol
*tmp_sym
= left_sym
;
530 const char *tmp_name
= left_name
;
532 left_name
= right_name
;
533 left_sym
= right_sym
;
534 right_name
= tmp_name
;
536 comparison
= flip_op(comparison
);
538 snprintf(state_name
, sizeof(state_name
), "%s vs %s", left_name
, right_name
);
539 state
= alloc_compare_state(left_name
, left_sym
, comparison
, right_name
, right_sym
);
541 set_state(compare_id
, state_name
, NULL
, state
);
542 save_link_var_sym(left_name
, left_sym
, state_name
);
543 save_link_var_sym(right_name
, right_sym
, state_name
);
546 static void add_comparison(struct expression
*left
, int comparison
, struct expression
*right
)
548 char *left_name
= NULL
;
549 char *right_name
= NULL
;
550 struct symbol
*left_sym
, *right_sym
;
552 left_name
= expr_to_var_sym(left
, &left_sym
);
553 if (!left_name
|| !left_sym
)
555 right_name
= expr_to_var_sym(right
, &right_sym
);
556 if (!right_name
|| !right_sym
)
559 add_comparison_var_sym(left_name
, left_sym
, comparison
, right_name
, right_sym
);
562 free_string(left_name
);
563 free_string(right_name
);
566 static void match_assign_add(struct expression
*expr
)
568 struct expression
*right
;
569 struct expression
*r_left
, *r_right
;
570 sval_t left_tmp
, right_tmp
;
572 right
= strip_expr(expr
->right
);
573 r_left
= strip_expr(right
->left
);
574 r_right
= strip_expr(right
->right
);
576 get_absolute_min(r_left
, &left_tmp
);
577 get_absolute_min(r_right
, &right_tmp
);
579 if (left_tmp
.value
> 0)
580 add_comparison(expr
->left
, '>', r_right
);
581 else if (left_tmp
.value
== 0)
582 add_comparison(expr
->left
, SPECIAL_GTE
, r_right
);
584 if (right_tmp
.value
> 0)
585 add_comparison(expr
->left
, '>', r_left
);
586 else if (right_tmp
.value
== 0)
587 add_comparison(expr
->left
, SPECIAL_GTE
, r_left
);
590 static void match_assign_sub(struct expression
*expr
)
592 struct expression
*right
;
593 struct expression
*r_left
, *r_right
;
597 right
= strip_expr(expr
->right
);
598 r_left
= strip_expr(right
->left
);
599 r_right
= strip_expr(right
->right
);
601 if (get_absolute_min(r_right
, &min
) && sval_is_negative(min
))
604 comparison
= get_comparison(r_left
, r_right
);
606 switch (comparison
) {
609 if (implied_not_equal(r_right
, 0))
610 add_comparison(expr
->left
, '>', r_left
);
612 add_comparison(expr
->left
, SPECIAL_GTE
, r_left
);
617 static void match_assign_divide(struct expression
*expr
)
619 struct expression
*right
;
620 struct expression
*r_left
, *r_right
;
623 right
= strip_expr(expr
->right
);
624 r_left
= strip_expr(right
->left
);
625 r_right
= strip_expr(right
->right
);
626 if (!get_implied_min(r_right
, &min
) || min
.value
<= 1)
629 add_comparison(expr
->left
, '<', r_left
);
632 static void match_binop_assign(struct expression
*expr
)
634 struct expression
*right
;
636 right
= strip_expr(expr
->right
);
637 if (right
->op
== '+')
638 match_assign_add(expr
);
639 if (right
->op
== '-')
640 match_assign_sub(expr
);
641 if (right
->op
== '/')
642 match_assign_divide(expr
);
645 static void copy_comparisons(struct expression
*left
, struct expression
*right
)
647 struct string_list
*links
;
648 struct smatch_state
*state
;
649 struct compare_data
*data
;
650 struct symbol
*left_sym
, *right_sym
;
651 char *left_var
= NULL
;
652 char *right_var
= NULL
;
658 left_var
= expr_to_var_sym(left
, &left_sym
);
659 if (!left_var
|| !left_sym
)
661 right_var
= expr_to_var_sym(right
, &right_sym
);
662 if (!right_var
|| !right_sym
)
665 state
= get_state_expr(link_id
, right
);
670 FOR_EACH_PTR(links
, tmp
) {
671 state
= get_state(compare_id
, tmp
, NULL
);
675 comparison
= data
->comparison
;
678 if (var_sym_eq(var
, sym
, right_var
, right_sym
)) {
681 comparison
= flip_op(comparison
);
683 add_comparison_var_sym(left_var
, left_sym
, comparison
, var
, sym
);
684 } END_FOR_EACH_PTR(tmp
);
687 free_string(right_var
);
690 static void match_normal_assign(struct expression
*expr
)
692 copy_comparisons(expr
->left
, expr
->right
);
693 add_comparison(expr
->left
, SPECIAL_EQUAL
, expr
->right
);
696 static void match_assign(struct expression
*expr
)
698 struct expression
*right
;
700 right
= strip_expr(expr
->right
);
701 if (right
->type
== EXPR_BINOP
)
702 match_binop_assign(expr
);
704 match_normal_assign(expr
);
707 static int get_comparison_strings(char *one
, char *two
)
710 struct smatch_state
*state
;
714 if (strcmp(one
, two
) > 0) {
722 snprintf(buf
, sizeof(buf
), "%s vs %s", one
, two
);
723 state
= get_state(compare_id
, buf
, NULL
);
725 ret
= state_to_comparison(state
);
733 int get_comparison(struct expression
*a
, struct expression
*b
)
739 one
= expr_to_var(a
);
742 two
= expr_to_var(b
);
746 ret
= get_comparison_strings(one
, two
);
753 void __add_comparison_info(struct expression
*expr
, struct expression
*call
, const char *range
)
755 struct expression
*arg
;
757 const char *c
= range
;
759 if (!str_to_comparison_arg(c
, call
, &comparison
, &arg
))
761 add_comparison(expr
, comparison
, arg
);
764 static char *range_comparison_to_param_helper(struct expression
*expr
, char starts_with
)
766 struct symbol
*param
;
769 char *ret_str
= NULL
;
773 var
= expr_to_var(expr
);
778 FOR_EACH_PTR(cur_func_sym
->ctype
.base_type
->arguments
, param
) {
782 snprintf(buf
, sizeof(buf
), "%s orig", param
->ident
->name
);
783 compare
= get_comparison_strings(var
, buf
);
786 if (show_special(compare
)[0] != starts_with
)
788 snprintf(buf
, sizeof(buf
), "[%sp%d]", show_special(compare
), i
);
789 ret_str
= alloc_sname(buf
);
791 } END_FOR_EACH_PTR(param
);
798 char *expr_equal_to_param(struct expression
*expr
)
800 return range_comparison_to_param_helper(expr
, '=');
803 char *expr_lte_to_param(struct expression
*expr
)
805 return range_comparison_to_param_helper(expr
, '<');
808 static void free_data(struct symbol
*sym
)
812 clear_compare_data_alloc();
815 void register_comparison(int id
)
818 add_hook(&match_compare
, CONDITION_HOOK
);
819 add_hook(&match_assign
, ASSIGNMENT_HOOK
);
820 add_hook(&save_start_states
, AFTER_DEF_HOOK
);
821 add_unmatched_state_hook(compare_id
, unmatched_comparison
);
822 add_merge_hook(compare_id
, &merge_compare_states
);
823 add_hook(&free_data
, AFTER_FUNC_HOOK
);
826 void register_comparison_links(int id
)
829 add_merge_hook(link_id
, &merge_links
);
830 add_modification_hook(link_id
, &match_modify
);