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 static struct smatch_state
*alloc_compare_state(
42 const char *var1
, struct symbol
*sym1
,
44 const char *var2
, struct symbol
*sym2
)
46 struct smatch_state
*state
;
47 struct compare_data
*data
;
49 state
= __alloc_smatch_state(0);
50 state
->name
= alloc_sname(show_special(comparison
));
51 data
= __alloc_compare_data(0);
52 data
->var1
= alloc_sname(var1
);
54 data
->comparison
= comparison
;
55 data
->var2
= alloc_sname(var2
);
61 static int state_to_comparison(struct smatch_state
*state
)
63 if (!state
|| !state
->data
)
65 return ((struct compare_data
*)state
->data
)->comparison
;
69 * flip_op() reverses the op left and right. So "x >= y" becomes "y <= x".
71 static int flip_op(int op
)
78 case SPECIAL_UNSIGNED_LT
:
79 return SPECIAL_UNSIGNED_GT
;
82 case SPECIAL_UNSIGNED_LTE
:
83 return SPECIAL_UNSIGNED_GTE
;
86 case SPECIAL_NOTEQUAL
:
87 return SPECIAL_NOTEQUAL
;
90 case SPECIAL_UNSIGNED_GTE
:
91 return SPECIAL_UNSIGNED_LTE
;
94 case SPECIAL_UNSIGNED_GT
:
95 return SPECIAL_UNSIGNED_LT
;
97 sm_msg("internal smatch bug. unhandled comparison %d", op
);
102 static int falsify_op(int op
)
109 case SPECIAL_UNSIGNED_LT
:
110 return SPECIAL_UNSIGNED_GTE
;
113 case SPECIAL_UNSIGNED_LTE
:
114 return SPECIAL_UNSIGNED_GT
;
116 return SPECIAL_NOTEQUAL
;
117 case SPECIAL_NOTEQUAL
:
118 return SPECIAL_EQUAL
;
121 case SPECIAL_UNSIGNED_GTE
:
122 return SPECIAL_UNSIGNED_LT
;
125 case SPECIAL_UNSIGNED_GT
:
126 return SPECIAL_UNSIGNED_LTE
;
128 sm_msg("internal smatch bug. unhandled comparison %d", op
);
133 static int rl_comparison(struct range_list
*left_rl
, struct range_list
*right_rl
)
135 sval_t left_min
, left_max
, right_min
, right_max
;
137 if (!left_rl
|| !right_rl
)
140 left_min
= rl_min(left_rl
);
141 left_max
= rl_max(left_rl
);
142 right_min
= rl_min(right_rl
);
143 right_max
= rl_max(right_rl
);
145 if (left_min
.value
== left_max
.value
&&
146 right_min
.value
== right_max
.value
&&
147 left_min
.value
== right_min
.value
)
148 return SPECIAL_EQUAL
;
150 if (sval_cmp(left_max
, right_min
) < 0)
152 if (sval_cmp(left_max
, right_min
) == 0)
154 if (sval_cmp(left_min
, right_max
) > 0)
156 if (sval_cmp(left_min
, right_max
) == 0)
162 static struct range_list
*get_orig_rl(struct symbol
*sym
)
164 struct smatch_state
*state
;
166 if (!sym
|| !sym
->ident
)
168 state
= get_orig_estate(sym
->ident
->name
, sym
);
169 return estate_rl(state
);
172 static struct smatch_state
*unmatched_comparison(struct sm_state
*sm
)
174 struct compare_data
*data
= sm
->state
->data
;
175 struct range_list
*left_rl
, *right_rl
;
181 if (strstr(data
->var1
, " orig"))
182 left_rl
= get_orig_rl(data
->sym1
);
183 else if (!get_implied_rl_var_sym(data
->var1
, data
->sym1
, &left_rl
))
185 if (strstr(data
->var2
, " orig"))
186 right_rl
= get_orig_rl(data
->sym2
);
187 else if (!get_implied_rl_var_sym(data
->var2
, data
->sym2
, &right_rl
))
190 op
= rl_comparison(left_rl
, right_rl
);
192 return alloc_compare_state(data
->var1
, data
->sym1
, op
, data
->var2
, data
->sym2
);
197 /* remove_unsigned_from_comparison() is obviously a hack. */
198 static int remove_unsigned_from_comparison(int op
)
201 case SPECIAL_UNSIGNED_LT
:
203 case SPECIAL_UNSIGNED_LTE
:
205 case SPECIAL_UNSIGNED_GTE
:
207 case SPECIAL_UNSIGNED_GT
:
214 static int merge_comparisons(int one
, int two
)
218 one
= remove_unsigned_from_comparison(one
);
219 two
= remove_unsigned_from_comparison(two
);
266 return SPECIAL_NOTEQUAL
;
276 static struct smatch_state
*merge_compare_states(struct smatch_state
*s1
, struct smatch_state
*s2
)
278 struct compare_data
*data
= s1
->data
;
281 op
= merge_comparisons(state_to_comparison(s1
), state_to_comparison(s2
));
283 return alloc_compare_state(data
->var1
, data
->sym1
, op
, data
->var2
, data
->sym2
);
287 struct smatch_state
*alloc_link_state(struct string_list
*links
)
289 struct smatch_state
*state
;
290 static char buf
[256];
294 state
= __alloc_smatch_state(0);
297 FOR_EACH_PTR(links
, tmp
) {
299 snprintf(buf
, sizeof(buf
), "%s", tmp
);
301 snprintf(buf
, sizeof(buf
), "%s, %s", buf
, tmp
);
302 } END_FOR_EACH_PTR(tmp
);
304 state
->name
= alloc_sname(buf
);
309 static void save_start_states(struct statement
*stmt
)
311 struct symbol
*param
;
313 char state_name
[128];
314 struct smatch_state
*state
;
315 struct string_list
*links
;
318 FOR_EACH_PTR(cur_func_sym
->ctype
.base_type
->arguments
, param
) {
321 snprintf(orig
, sizeof(orig
), "%s orig", param
->ident
->name
);
322 snprintf(state_name
, sizeof(state_name
), "%s vs %s", param
->ident
->name
, orig
);
323 state
= alloc_compare_state(param
->ident
->name
, param
, SPECIAL_EQUAL
, alloc_sname(orig
), param
);
324 set_state(compare_id
, state_name
, NULL
, state
);
326 link
= alloc_sname(state_name
);
328 insert_string(&links
, link
);
329 state
= alloc_link_state(links
);
330 set_state(link_id
, param
->ident
->name
, param
, state
);
331 } END_FOR_EACH_PTR(param
);
334 static struct smatch_state
*merge_links(struct smatch_state
*s1
, struct smatch_state
*s2
)
336 struct smatch_state
*ret
;
337 struct string_list
*links
;
339 links
= combine_string_lists(s1
->data
, s2
->data
);
340 ret
= alloc_link_state(links
);
344 static void save_link_var_sym(const char *var
, struct symbol
*sym
, char *link
)
346 struct smatch_state
*old_state
, *new_state
;
347 struct string_list
*links
;
350 old_state
= get_state(link_id
, var
, sym
);
352 links
= clone_str_list(old_state
->data
);
356 new = alloc_sname(link
);
357 insert_string(&links
, new);
359 new_state
= alloc_link_state(links
);
360 set_state(link_id
, var
, sym
, new_state
);
363 static void save_link(struct expression
*expr
, char *link
)
368 var
= expr_to_var_sym(expr
, &sym
);
372 save_link_var_sym(var
, sym
, link
);
377 static void match_inc(struct sm_state
*sm
)
379 struct string_list
*links
;
380 struct smatch_state
*state
;
383 links
= sm
->state
->data
;
385 FOR_EACH_PTR(links
, tmp
) {
386 state
= get_state(compare_id
, tmp
, NULL
);
388 switch (state_to_comparison(state
)) {
391 case SPECIAL_UNSIGNED_GTE
:
393 case SPECIAL_UNSIGNED_GT
: {
394 struct compare_data
*data
= state
->data
;
395 struct smatch_state
*new;
397 new = alloc_compare_state(data
->var1
, data
->sym1
, '>', data
->var2
, data
->sym2
);
398 set_state(compare_id
, tmp
, NULL
, new);
402 set_state(compare_id
, tmp
, NULL
, &undefined
);
404 } END_FOR_EACH_PTR(tmp
);
407 static void match_dec(struct sm_state
*sm
)
409 struct string_list
*links
;
410 struct smatch_state
*state
;
413 links
= sm
->state
->data
;
415 FOR_EACH_PTR(links
, tmp
) {
416 state
= get_state(compare_id
, tmp
, NULL
);
418 switch (state_to_comparison(state
)) {
421 case SPECIAL_UNSIGNED_LTE
:
423 case SPECIAL_UNSIGNED_LT
: {
424 struct compare_data
*data
= state
->data
;
425 struct smatch_state
*new;
427 new = alloc_compare_state(data
->var1
, data
->sym1
, '<', data
->var2
, data
->sym2
);
428 set_state(compare_id
, tmp
, NULL
, new);
432 set_state(compare_id
, tmp
, NULL
, &undefined
);
434 } END_FOR_EACH_PTR(tmp
);
437 static int match_inc_dec(struct sm_state
*sm
, struct expression
*mod_expr
)
441 if (mod_expr
->type
!= EXPR_PREOP
&& mod_expr
->type
!= EXPR_POSTOP
)
444 if (mod_expr
->op
== SPECIAL_INCREMENT
) {
448 if (mod_expr
->op
== SPECIAL_DECREMENT
) {
455 static void match_modify(struct sm_state
*sm
, struct expression
*mod_expr
)
457 struct string_list
*links
;
460 if (match_inc_dec(sm
, mod_expr
))
463 links
= sm
->state
->data
;
465 FOR_EACH_PTR(links
, tmp
) {
466 set_state(compare_id
, tmp
, NULL
, &undefined
);
467 } END_FOR_EACH_PTR(tmp
);
468 set_state(link_id
, sm
->name
, sm
->sym
, &undefined
);
471 static void match_compare(struct expression
*expr
)
475 struct symbol
*left_sym
, *right_sym
;
477 struct smatch_state
*true_state
, *false_state
;
478 char state_name
[256];
480 if (expr
->type
!= EXPR_COMPARE
)
482 left
= expr_to_var_sym(expr
->left
, &left_sym
);
483 if (!left
|| !left_sym
)
485 right
= expr_to_var_sym(expr
->right
, &right_sym
);
486 if (!right
|| !right_sym
)
489 if (strcmp(left
, right
) > 0) {
490 struct symbol
*tmp_sym
= left_sym
;
491 char *tmp_name
= left
;
494 left_sym
= right_sym
;
497 op
= flip_op(expr
->op
);
501 false_op
= falsify_op(op
);
502 snprintf(state_name
, sizeof(state_name
), "%s vs %s", left
, right
);
503 true_state
= alloc_compare_state(left
, left_sym
, op
, right
, right_sym
);
504 false_state
= alloc_compare_state(left
, left_sym
, false_op
, right
, right_sym
);
506 set_true_false_states(compare_id
, state_name
, NULL
, true_state
, false_state
);
507 save_link(expr
->left
, state_name
);
508 save_link(expr
->right
, state_name
);
514 static void add_comparison_var_sym(const char *left_name
, struct symbol
*left_sym
, int comparison
, const char *right_name
, struct symbol
*right_sym
)
516 struct smatch_state
*state
;
517 char state_name
[256];
519 if (strcmp(left_name
, right_name
) > 0) {
520 struct symbol
*tmp_sym
= left_sym
;
521 const char *tmp_name
= left_name
;
523 left_name
= right_name
;
524 left_sym
= right_sym
;
525 right_name
= tmp_name
;
527 comparison
= flip_op(comparison
);
529 snprintf(state_name
, sizeof(state_name
), "%s vs %s", left_name
, right_name
);
530 state
= alloc_compare_state(left_name
, left_sym
, comparison
, right_name
, right_sym
);
532 set_state(compare_id
, state_name
, NULL
, state
);
533 save_link_var_sym(left_name
, left_sym
, state_name
);
534 save_link_var_sym(right_name
, right_sym
, state_name
);
537 static void add_comparison(struct expression
*left
, int comparison
, struct expression
*right
)
539 char *left_name
= NULL
;
540 char *right_name
= NULL
;
541 struct symbol
*left_sym
, *right_sym
;
543 left_name
= expr_to_var_sym(left
, &left_sym
);
544 if (!left_name
|| !left_sym
)
546 right_name
= expr_to_var_sym(right
, &right_sym
);
547 if (!right_name
|| !right_sym
)
550 add_comparison_var_sym(left_name
, left_sym
, comparison
, right_name
, right_sym
);
553 free_string(left_name
);
554 free_string(right_name
);
557 static void match_assign_add(struct expression
*expr
)
559 struct expression
*right
;
560 struct expression
*r_left
, *r_right
;
561 sval_t left_tmp
, right_tmp
;
563 right
= strip_expr(expr
->right
);
564 r_left
= strip_expr(right
->left
);
565 r_right
= strip_expr(right
->right
);
567 get_absolute_min(r_left
, &left_tmp
);
568 get_absolute_min(r_right
, &right_tmp
);
570 if (left_tmp
.value
> 0)
571 add_comparison(expr
->left
, '>', r_right
);
572 else if (left_tmp
.value
== 0)
573 add_comparison(expr
->left
, SPECIAL_GTE
, r_right
);
575 if (right_tmp
.value
> 0)
576 add_comparison(expr
->left
, '>', r_left
);
577 else if (right_tmp
.value
== 0)
578 add_comparison(expr
->left
, SPECIAL_GTE
, r_left
);
581 static void match_assign_sub(struct expression
*expr
)
583 struct expression
*right
;
584 struct expression
*r_left
, *r_right
;
588 right
= strip_expr(expr
->right
);
589 r_left
= strip_expr(right
->left
);
590 r_right
= strip_expr(right
->right
);
592 if (get_absolute_min(r_right
, &min
) && sval_is_negative(min
))
595 comparison
= get_comparison(r_left
, r_right
);
597 switch (comparison
) {
600 if (implied_not_equal(r_right
, 0))
601 add_comparison(expr
->left
, '>', r_left
);
603 add_comparison(expr
->left
, SPECIAL_GTE
, r_left
);
608 static void match_assign_divide(struct expression
*expr
)
610 struct expression
*right
;
611 struct expression
*r_left
, *r_right
;
614 right
= strip_expr(expr
->right
);
615 r_left
= strip_expr(right
->left
);
616 r_right
= strip_expr(right
->right
);
617 if (!get_implied_min(r_right
, &min
) || min
.value
<= 1)
620 add_comparison(expr
->left
, '<', r_left
);
623 static void match_binop_assign(struct expression
*expr
)
625 struct expression
*right
;
627 right
= strip_expr(expr
->right
);
628 if (right
->op
== '+')
629 match_assign_add(expr
);
630 if (right
->op
== '-')
631 match_assign_sub(expr
);
632 if (right
->op
== '/')
633 match_assign_divide(expr
);
636 static void copy_comparisons(struct expression
*left
, struct expression
*right
)
638 struct string_list
*links
;
639 struct smatch_state
*state
;
640 struct compare_data
*data
;
641 struct symbol
*left_sym
, *right_sym
;
642 char *left_var
= NULL
;
643 char *right_var
= NULL
;
649 left_var
= expr_to_var_sym(left
, &left_sym
);
650 if (!left_var
|| !left_sym
)
652 right_var
= expr_to_var_sym(right
, &right_sym
);
653 if (!right_var
|| !right_sym
)
656 state
= get_state_expr(link_id
, right
);
661 FOR_EACH_PTR(links
, tmp
) {
662 state
= get_state(compare_id
, tmp
, NULL
);
666 comparison
= data
->comparison
;
669 if (sym
== right_sym
&& strcmp(var
, right_var
) == 0) {
672 comparison
= flip_op(comparison
);
674 add_comparison_var_sym(left_var
, left_sym
, comparison
, var
, sym
);
675 } END_FOR_EACH_PTR(tmp
);
678 free_string(right_var
);
681 static void match_normal_assign(struct expression
*expr
)
683 copy_comparisons(expr
->left
, expr
->right
);
684 add_comparison(expr
->left
, SPECIAL_EQUAL
, expr
->right
);
687 static void match_assign(struct expression
*expr
)
689 struct expression
*right
;
691 right
= strip_expr(expr
->right
);
692 if (right
->type
== EXPR_BINOP
)
693 match_binop_assign(expr
);
695 match_normal_assign(expr
);
698 static int get_comparison_strings(char *one
, char *two
)
701 struct smatch_state
*state
;
705 if (strcmp(one
, two
) > 0) {
713 snprintf(buf
, sizeof(buf
), "%s vs %s", one
, two
);
714 state
= get_state(compare_id
, buf
, NULL
);
716 ret
= state_to_comparison(state
);
724 int get_comparison(struct expression
*a
, struct expression
*b
)
730 one
= expr_to_var(a
);
733 two
= expr_to_var(b
);
737 ret
= get_comparison_strings(one
, two
);
744 void __add_comparison_info(struct expression
*expr
, struct expression
*call
, const char *range
)
746 struct expression
*arg
;
748 const char *c
= range
;
750 if (!str_to_comparison_arg(c
, call
, &comparison
, &arg
))
752 add_comparison(expr
, comparison
, arg
);
755 static char *range_comparison_to_param_helper(struct expression
*expr
, char starts_with
)
757 struct symbol
*param
;
760 char *ret_str
= NULL
;
764 var
= expr_to_var(expr
);
769 FOR_EACH_PTR(cur_func_sym
->ctype
.base_type
->arguments
, param
) {
773 snprintf(buf
, sizeof(buf
), "%s orig", param
->ident
->name
);
774 compare
= get_comparison_strings(var
, buf
);
777 if (show_special(compare
)[0] != starts_with
)
779 snprintf(buf
, sizeof(buf
), "[%sp%d]", show_special(compare
), i
);
780 ret_str
= alloc_sname(buf
);
782 } END_FOR_EACH_PTR(param
);
789 char *expr_equal_to_param(struct expression
*expr
)
791 return range_comparison_to_param_helper(expr
, '=');
794 char *expr_lte_to_param(struct expression
*expr
)
796 return range_comparison_to_param_helper(expr
, '<');
799 static void free_data(struct symbol
*sym
)
803 clear_compare_data_alloc();
806 void register_comparison(int id
)
809 add_hook(&match_compare
, CONDITION_HOOK
);
810 add_hook(&match_assign
, ASSIGNMENT_HOOK
);
811 add_hook(&save_start_states
, AFTER_DEF_HOOK
);
812 add_unmatched_state_hook(compare_id
, unmatched_comparison
);
813 add_merge_hook(compare_id
, &merge_compare_states
);
814 add_hook(&free_data
, AFTER_FUNC_HOOK
);
817 void register_comparison_links(int id
)
820 add_merge_hook(link_id
, &merge_links
);
821 add_modification_hook(link_id
, &match_modify
);