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
,
43 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
->var2
= alloc_sname(var2
);
56 data
->comparison
= comparison
;
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 smatch_state
*unmatched_comparison(struct sm_state
*sm
)
164 struct compare_data
*data
= sm
->state
->data
;
165 struct range_list
*left_rl
, *right_rl
;
171 if (!get_implied_rl_var_sym(data
->var1
, data
->sym1
, &left_rl
))
173 if (!get_implied_rl_var_sym(data
->var2
, data
->sym2
, &right_rl
))
176 op
= rl_comparison(left_rl
, right_rl
);
178 return alloc_compare_state(data
->var1
, data
->sym1
, data
->var2
, data
->sym2
, op
);
183 /* remove_unsigned_from_comparison() is obviously a hack. */
184 static int remove_unsigned_from_comparison(int op
)
187 case SPECIAL_UNSIGNED_LT
:
189 case SPECIAL_UNSIGNED_LTE
:
191 case SPECIAL_UNSIGNED_GTE
:
193 case SPECIAL_UNSIGNED_GT
:
200 static int merge_comparisons(int one
, int two
)
204 one
= remove_unsigned_from_comparison(one
);
205 two
= remove_unsigned_from_comparison(two
);
252 return SPECIAL_NOTEQUAL
;
262 static struct smatch_state
*merge_compare_states(struct smatch_state
*s1
, struct smatch_state
*s2
)
264 struct compare_data
*data
= s1
->data
;
267 op
= merge_comparisons(state_to_comparison(s1
), state_to_comparison(s2
));
269 return alloc_compare_state(data
->var1
, data
->sym1
, data
->var2
, data
->sym2
, op
);
273 struct smatch_state
*alloc_link_state(struct string_list
*links
)
275 struct smatch_state
*state
;
276 static char buf
[256];
280 state
= __alloc_smatch_state(0);
283 FOR_EACH_PTR(links
, tmp
) {
285 snprintf(buf
, sizeof(buf
), "%s", tmp
);
287 snprintf(buf
, sizeof(buf
), "%s, %s", buf
, tmp
);
288 } END_FOR_EACH_PTR(tmp
);
290 state
->name
= alloc_sname(buf
);
295 static void save_start_states(struct statement
*stmt
)
297 struct symbol
*param
;
299 char state_name
[128];
300 struct smatch_state
*state
;
301 struct string_list
*links
;
304 FOR_EACH_PTR(cur_func_sym
->ctype
.base_type
->arguments
, param
) {
307 snprintf(orig
, sizeof(orig
), "%s orig", param
->ident
->name
);
308 snprintf(state_name
, sizeof(state_name
), "%s vs %s", param
->ident
->name
, orig
);
309 state
= alloc_compare_state(param
->ident
->name
, param
, alloc_sname(orig
), NULL
, SPECIAL_EQUAL
);
310 set_state(compare_id
, state_name
, NULL
, state
);
312 link
= alloc_sname(state_name
);
314 insert_string(&links
, link
);
315 state
= alloc_link_state(links
);
316 set_state(link_id
, param
->ident
->name
, param
, state
);
317 } END_FOR_EACH_PTR(param
);
320 static struct smatch_state
*merge_links(struct smatch_state
*s1
, struct smatch_state
*s2
)
322 struct smatch_state
*ret
;
323 struct string_list
*links
;
325 links
= combine_string_lists(s1
->data
, s2
->data
);
326 ret
= alloc_link_state(links
);
330 static void save_link(struct expression
*expr
, char *link
)
332 struct smatch_state
*old_state
, *new_state
;
333 struct string_list
*links
;
336 old_state
= get_state_expr(link_id
, expr
);
338 links
= clone_str_list(old_state
->data
);
342 new = alloc_sname(link
);
343 insert_string(&links
, new);
345 new_state
= alloc_link_state(links
);
346 set_state_expr(link_id
, expr
, new_state
);
349 static void match_inc(struct sm_state
*sm
)
351 struct string_list
*links
;
352 struct smatch_state
*state
;
355 links
= sm
->state
->data
;
357 FOR_EACH_PTR(links
, tmp
) {
358 state
= get_state(compare_id
, tmp
, NULL
);
360 switch (state_to_comparison(state
)) {
363 case SPECIAL_UNSIGNED_GTE
:
365 case SPECIAL_UNSIGNED_GT
: {
366 struct compare_data
*data
= state
->data
;
367 struct smatch_state
*new;
369 new = alloc_compare_state(data
->var1
, data
->sym1
, data
->var2
, data
->sym2
, '>');
370 set_state(compare_id
, tmp
, NULL
, new);
374 set_state(compare_id
, tmp
, NULL
, &undefined
);
376 } END_FOR_EACH_PTR(tmp
);
379 static void match_dec(struct sm_state
*sm
)
381 struct string_list
*links
;
382 struct smatch_state
*state
;
385 links
= sm
->state
->data
;
387 FOR_EACH_PTR(links
, tmp
) {
388 state
= get_state(compare_id
, tmp
, NULL
);
390 switch (state_to_comparison(state
)) {
393 case SPECIAL_UNSIGNED_LTE
:
395 case SPECIAL_UNSIGNED_LT
: {
396 struct compare_data
*data
= state
->data
;
397 struct smatch_state
*new;
399 new = alloc_compare_state(data
->var1
, data
->sym1
, data
->var2
, data
->sym2
, '<');
400 set_state(compare_id
, tmp
, NULL
, new);
404 set_state(compare_id
, tmp
, NULL
, &undefined
);
406 } END_FOR_EACH_PTR(tmp
);
409 static int match_inc_dec(struct sm_state
*sm
, struct expression
*mod_expr
)
413 if (mod_expr
->type
!= EXPR_PREOP
&& mod_expr
->type
!= EXPR_POSTOP
)
416 if (mod_expr
->op
== SPECIAL_INCREMENT
) {
420 if (mod_expr
->op
== SPECIAL_DECREMENT
) {
427 static void match_modify(struct sm_state
*sm
, struct expression
*mod_expr
)
429 struct string_list
*links
;
432 if (match_inc_dec(sm
, mod_expr
))
435 links
= sm
->state
->data
;
437 FOR_EACH_PTR(links
, tmp
) {
438 set_state(compare_id
, tmp
, NULL
, &undefined
);
439 } END_FOR_EACH_PTR(tmp
);
440 set_state(link_id
, sm
->name
, sm
->sym
, &undefined
);
443 static void match_logic(struct expression
*expr
)
447 struct symbol
*left_sym
, *right_sym
;
449 struct smatch_state
*true_state
, *false_state
;
450 char state_name
[256];
452 if (expr
->type
!= EXPR_COMPARE
)
454 left
= expr_to_var_sym(expr
->left
, &left_sym
);
455 if (!left
|| !left_sym
)
457 right
= expr_to_var_sym(expr
->right
, &right_sym
);
458 if (!right
|| !right_sym
)
461 if (strcmp(left
, right
) > 0) {
462 struct symbol
*tmp_sym
= left_sym
;
463 char *tmp_name
= left
;
466 left_sym
= right_sym
;
469 op
= flip_op(expr
->op
);
473 false_op
= falsify_op(op
);
474 snprintf(state_name
, sizeof(state_name
), "%s vs %s", left
, right
);
475 true_state
= alloc_compare_state(left
, left_sym
, right
, right_sym
, op
);
476 false_state
= alloc_compare_state(left
, left_sym
, right
, right_sym
, false_op
);
478 set_true_false_states(compare_id
, state_name
, NULL
, true_state
, false_state
);
479 save_link(expr
->left
, state_name
);
480 save_link(expr
->right
, state_name
);
486 static void add_comparison(struct expression
*left
, int comparison
, struct expression
*right
)
488 char *left_name
= NULL
;
489 char *right_name
= NULL
;
490 struct symbol
*left_sym
, *right_sym
;
491 struct smatch_state
*state
;
492 char state_name
[256];
494 left_name
= expr_to_var_sym(left
, &left_sym
);
495 if (!left_name
|| !left_sym
)
497 right_name
= expr_to_var_sym(right
, &right_sym
);
498 if (!right_name
|| !right_sym
)
501 if (strcmp(left_name
, right_name
) > 0) {
502 struct symbol
*tmp_sym
= left_sym
;
503 char *tmp_name
= left_name
;
505 left_name
= right_name
;
506 left_sym
= right_sym
;
507 right_name
= tmp_name
;
509 comparison
= flip_op(comparison
);
511 snprintf(state_name
, sizeof(state_name
), "%s vs %s", left_name
, right_name
);
512 state
= alloc_compare_state(left_name
, left_sym
, right_name
, right_sym
, comparison
);
514 set_state(compare_id
, state_name
, NULL
, state
);
515 save_link(left
, state_name
);
516 save_link(right
, state_name
);
518 free_string(left_name
);
519 free_string(right_name
);
523 static void match_assign_add(struct expression
*expr
)
525 struct expression
*right
;
526 struct expression
*r_left
, *r_right
;
527 sval_t left_tmp
, right_tmp
;
529 right
= strip_expr(expr
->right
);
530 r_left
= strip_expr(right
->left
);
531 r_right
= strip_expr(right
->right
);
533 if (!is_capped(expr
->left
)) {
534 get_absolute_max(r_left
, &left_tmp
);
535 get_absolute_max(r_right
, &right_tmp
);
536 if (sval_binop_overflows(left_tmp
, '+', right_tmp
))
540 get_absolute_min(r_left
, &left_tmp
);
541 if (sval_is_negative(left_tmp
))
543 get_absolute_min(r_right
, &right_tmp
);
544 if (sval_is_negative(right_tmp
))
547 if (left_tmp
.value
== 0)
548 add_comparison(expr
->left
, SPECIAL_GTE
, r_right
);
550 add_comparison(expr
->left
, '>', r_right
);
552 if (right_tmp
.value
== 0)
553 add_comparison(expr
->left
, SPECIAL_GTE
, r_left
);
555 add_comparison(expr
->left
, '>', r_left
);
558 static void match_assign_sub(struct expression
*expr
)
560 struct expression
*right
;
561 struct expression
*r_left
, *r_right
;
565 right
= strip_expr(expr
->right
);
566 r_left
= strip_expr(right
->left
);
567 r_right
= strip_expr(right
->right
);
569 if (get_absolute_min(r_right
, &min
) && sval_is_negative(min
))
572 comparison
= get_comparison(r_left
, r_right
);
574 switch (comparison
) {
577 if (implied_not_equal(r_right
, 0))
578 add_comparison(expr
->left
, '>', r_left
);
580 add_comparison(expr
->left
, SPECIAL_GTE
, r_left
);
585 static void match_binop_assign(struct expression
*expr
)
587 struct expression
*right
;
589 right
= strip_expr(expr
->right
);
590 if (right
->op
== '+')
591 match_assign_add(expr
);
592 if (right
->op
== '-')
593 match_assign_sub(expr
);
596 static void match_normal_assign(struct expression
*expr
)
598 add_comparison(expr
->left
, SPECIAL_EQUAL
, expr
->right
);
601 static void match_assign(struct expression
*expr
)
603 struct expression
*right
;
605 right
= strip_expr(expr
->right
);
606 if (right
->type
== EXPR_BINOP
)
607 match_binop_assign(expr
);
609 match_normal_assign(expr
);
612 static int get_comparison_strings(char *one
, char *two
)
615 struct smatch_state
*state
;
619 if (strcmp(one
, two
) > 0) {
627 snprintf(buf
, sizeof(buf
), "%s vs %s", one
, two
);
628 state
= get_state(compare_id
, buf
, NULL
);
630 ret
= state_to_comparison(state
);
638 int get_comparison(struct expression
*a
, struct expression
*b
)
644 one
= expr_to_var(a
);
647 two
= expr_to_var(b
);
651 ret
= get_comparison_strings(one
, two
);
658 void __add_comparison_info(struct expression
*expr
, struct expression
*call
, const char *range
)
660 struct expression
*arg
;
662 const char *c
= range
;
664 if (!str_to_comparison_arg(c
, call
, &comparison
, &arg
))
666 add_comparison(expr
, SPECIAL_LTE
, arg
);
669 static char *range_comparison_to_param_helper(struct expression
*expr
, char starts_with
)
671 struct symbol
*param
;
674 char *ret_str
= NULL
;
678 var
= expr_to_var(expr
);
683 FOR_EACH_PTR(cur_func_sym
->ctype
.base_type
->arguments
, param
) {
687 snprintf(buf
, sizeof(buf
), "%s orig", param
->ident
->name
);
688 compare
= get_comparison_strings(var
, buf
);
691 if (show_special(compare
)[0] != starts_with
)
693 snprintf(buf
, sizeof(buf
), "[%sp%d]", show_special(compare
), i
);
694 ret_str
= alloc_sname(buf
);
696 } END_FOR_EACH_PTR(param
);
703 char *expr_equal_to_param(struct expression
*expr
)
705 return range_comparison_to_param_helper(expr
, '=');
708 char *expr_lte_to_param(struct expression
*expr
)
710 return range_comparison_to_param_helper(expr
, '<');
713 static void free_data(struct symbol
*sym
)
717 clear_compare_data_alloc();
720 void register_comparison(int id
)
723 add_hook(&match_logic
, CONDITION_HOOK
);
724 add_hook(&match_assign
, ASSIGNMENT_HOOK
);
725 add_hook(&save_start_states
, AFTER_DEF_HOOK
);
726 add_unmatched_state_hook(compare_id
, unmatched_comparison
);
727 add_merge_hook(compare_id
, &merge_compare_states
);
728 add_hook(&free_data
, AFTER_FUNC_HOOK
);
731 void register_comparison_links(int id
)
734 add_merge_hook(link_id
, &merge_links
);
735 add_modification_hook(link_id
, &match_modify
);