2 * Copyright (C) 2008 Dan Carpenter.
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version 2
7 * of the License, or (at your option) any later version.
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, see http://www.gnu.org/copyleft/gpl.txt
19 * Imagine we have this code:
26 * if (foo == 99) // <-- point #2
27 * bar->baz; // <-- point #3
30 * At point #3 bar is non null and can be dereferenced.
32 * It's smatch_implied.c which sets bar to non null at point #2.
34 * At point #1 merge_slist() stores the list of states from both
35 * the true and false paths. On the true path foo == 99 and on
36 * the false path foo == 1. merge_slist() sets their pool
37 * list to show the other states which were there when foo == 99.
39 * When it comes to the if (foo == 99) the smatch implied hook
40 * looks for all the pools where foo was not 99. It makes a list
43 * Then for bar (and all the other states) it says, ok bar is a
44 * merged state that came from these previous states. We'll
45 * chop out all the states where it came from a pool where
46 * foo != 99 and merge it all back together.
48 * That is the implied state of bar.
50 * merge_slist() sets up ->pool. An sm_state only has one ->pool and
51 * that is the pool where it was first set. The my pool gets set when
52 * code paths merge. States that have been set since the last merge do
54 * merge_sm_state() sets ->left and ->right. (These are the states which were
55 * merged to form the current state.)
56 * a pool: a pool is an slist that has been merged with another slist.
62 #include "smatch_slist.h"
63 #include "smatch_extra.h"
65 char *implied_debug_msg
;
66 #define DIMPLIED(msg...) do { if (option_debug_implied) printf(msg); } while (0)
68 int option_debug_implied
= 0;
69 int option_no_implied
= 0;
76 * It messes things up to free range list allocations. This helper fuction
77 * lets us reuse memory instead of doing new allocations.
79 static struct range_list
*tmp_range_list(long long num
)
81 static struct range_list
*my_list
= NULL
;
82 static struct data_range
*my_range
;
84 __free_ptr_list((struct ptr_list
**)&my_list
);
85 my_range
= alloc_range(ll_to_sval(num
), ll_to_sval(num
));
86 add_ptr_list(&my_list
, my_range
);
90 static void print_debug_tf(struct sm_state
*s
, int istrue
, int isfalse
)
92 if (!option_debug_implied
&& !option_debug
)
95 if (istrue
&& isfalse
) {
96 printf("'%s = %s' from %d does not exist.\n", s
->name
,
97 show_state(s
->state
), s
->line
);
99 printf("'%s = %s' from %d is true. [stree %d]\n", s
->name
, show_state(s
->state
),
100 s
->line
, get_stree_id(s
->pool
));
101 } else if (isfalse
) {
102 printf("'%s = %s' from %d is false. [stree %d]\n", s
->name
, show_state(s
->state
),
103 s
->line
, get_stree_id(s
->pool
));
105 printf("'%s = %s' from %d could be true or false. [stree %d]\n", s
->name
,
106 show_state(s
->state
), s
->line
, get_stree_id(s
->pool
));
111 * add_pool() adds a slist to *pools. If the slist has already been
112 * added earlier then it doesn't get added a second time.
114 void add_pool(struct stree_stack
**pools
, struct stree
*new)
118 FOR_EACH_PTR(*pools
, tmp
) {
121 else if (tmp
== new) {
124 INSERT_CURRENT(new, tmp
);
127 } END_FOR_EACH_PTR(tmp
);
128 add_ptr_list(pools
, new);
132 * If 'foo' == 99 add it that pool to the true pools. If it's false, add it to
133 * the false pools. If we're not sure, then we don't add it to either.
135 static void do_compare(struct sm_state
*sm_state
, int comparison
, struct range_list
*vals
,
137 struct stree_stack
**true_stack
,
138 struct stree_stack
**false_stack
)
147 if (is_implied(sm_state
)) {
148 s
= get_sm_state_stree(sm_state
->pool
,
149 sm_state
->owner
, sm_state
->name
,
156 if (option_debug_implied
|| option_debug
)
157 sm_msg("%s from %d, has borrowed implications.",
158 sm_state
->name
, sm_state
->line
);
163 istrue
= !possibly_false_rl(estate_rl(s
->state
), comparison
, vals
);
164 isfalse
= !possibly_true_rl(estate_rl(s
->state
), comparison
, vals
);
166 istrue
= !possibly_false_rl(vals
, comparison
, estate_rl(s
->state
));
167 isfalse
= !possibly_true_rl(vals
, comparison
, estate_rl(s
->state
));
170 print_debug_tf(s
, istrue
, isfalse
);
173 add_pool(true_stack
, s
->pool
);
176 add_pool(false_stack
, s
->pool
);
179 static int pool_in_pools(struct stree
*pool
,
180 struct stree_stack
*pools
)
184 FOR_EACH_PTR(pools
, tmp
) {
189 } END_FOR_EACH_PTR(tmp
);
193 static int is_checked(struct state_list
*checked
, struct sm_state
*sm
)
195 struct sm_state
*tmp
;
197 FOR_EACH_PTR(checked
, tmp
) {
200 } END_FOR_EACH_PTR(tmp
);
206 * Example code: if (foo == 99) {
208 * Say 'foo' is a merged state that has many possible values. It is the combination
209 * of merges. separate_pools() iterates through the pools recursively and calls
210 * do_compare() for each time 'foo' was set.
212 static void separate_pools(struct sm_state
*sm_state
, int comparison
, struct range_list
*vals
,
214 struct stree_stack
**true_stack
,
215 struct stree_stack
**false_stack
,
216 struct state_list
**checked
)
218 int free_checked
= 0;
219 struct state_list
*checked_states
= NULL
;
225 Sometimes the implications are just too big to deal with
226 so we bail. Theoretically, bailing out here can cause more false
227 positives but won't hide actual bugs.
229 if (sm_state
->nr_children
> 4000) {
230 static char buf
[1028];
231 snprintf(buf
, sizeof(buf
), "debug: separate_pools: nr_children over 4000 (%d). (%s %s)",
232 sm_state
->nr_children
, sm_state
->name
, show_state(sm_state
->state
));
233 implied_debug_msg
= buf
;
237 if (checked
== NULL
) {
238 checked
= &checked_states
;
241 if (is_checked(*checked
, sm_state
))
243 add_ptr_list(checked
, sm_state
);
245 do_compare(sm_state
, comparison
, vals
, lr
, true_stack
, false_stack
);
247 separate_pools(sm_state
->left
, comparison
, vals
, lr
, true_stack
, false_stack
, checked
);
248 separate_pools(sm_state
->right
, comparison
, vals
, lr
, true_stack
, false_stack
, checked
);
253 struct sm_state
*filter_pools(struct sm_state
*sm
,
254 struct stree_stack
*remove_stack
,
255 struct stree_stack
*keep_stack
,
258 struct sm_state
*ret
= NULL
;
259 struct sm_state
*left
;
260 struct sm_state
*right
;
266 if (sm
->nr_children
> 4000) {
267 static char buf
[1028];
268 snprintf(buf
, sizeof(buf
), "debug: %s: nr_children over 4000 (%d). (%s %s)",
269 __func__
, sm
->nr_children
, sm
->name
, show_state(sm
->state
));
270 implied_debug_msg
= buf
;
274 if (pool_in_pools(sm
->pool
, remove_stack
)) {
275 DIMPLIED("removed %s from %d [stree %d]\n", show_sm(sm
), sm
->line
, get_stree_id(sm
->pool
));
280 if (!is_merged(sm
) || pool_in_pools(sm
->pool
, keep_stack
)) {
281 DIMPLIED("kept %s from %d [stree %d]\n", show_sm(sm
), sm
->line
, get_stree_id(sm
->pool
));
285 DIMPLIED("checking %s from %d (%d) [stree %d] left = %s [stree %d] right = %s [stree %d]\n",
286 show_sm(sm
), sm
->line
, sm
->nr_children
, get_stree_id(sm
->pool
),
287 sm
->left
? show_sm(sm
->left
) : "<none>", sm
->left
? get_stree_id(sm
->left
->pool
) : -1,
288 sm
->right
? show_sm(sm
->right
) : "<none>", sm
->right
? get_stree_id(sm
->right
->pool
) : -1);
289 left
= filter_pools(sm
->left
, remove_stack
, keep_stack
, &removed
);
290 right
= filter_pools(sm
->right
, remove_stack
, keep_stack
, &removed
);
292 DIMPLIED("kept %s from %d [stree %d]\n", show_sm(sm
), sm
->line
, get_stree_id(sm
->pool
));
296 if (!left
&& !right
) {
297 DIMPLIED("removed %s from %d <none> [stree %d]\n", show_sm(sm
), sm
->line
, get_stree_id(sm
->pool
));
302 ret
= clone_sm(right
);
306 ret
->pool
= sm
->pool
;
308 ret
= clone_sm(left
);
312 ret
->pool
= sm
->pool
;
314 ret
= merge_sm_states(left
, right
);
315 ret
->pool
= sm
->pool
;
318 DIMPLIED("partial %s => ", show_sm(sm
));
319 DIMPLIED("%s from %d [stree %d]\n", show_sm(ret
), sm
->line
, get_stree_id(sm
->pool
));
323 static int highest_stree_id(struct sm_state
*sm
)
328 if (!sm
->left
&& !sm
->right
)
332 left
= get_stree_id(sm
->left
->pool
);
334 right
= get_stree_id(sm
->right
->pool
);
341 static struct stree
*filter_stack(struct sm_state
*gate_sm
,
342 struct stree
*pre_stree
,
343 struct stree_stack
*remove_stack
,
344 struct stree_stack
*keep_stack
)
346 struct stree
*ret
= NULL
;
347 struct sm_state
*tmp
;
348 struct sm_state
*filtered_sm
;
354 FOR_EACH_SM(pre_stree
, tmp
) {
355 if (highest_stree_id(tmp
) < highest_stree_id(gate_sm
)) {
356 DIMPLIED("skipping %s. set before. %d vs %d\n",
357 tmp
->name
, highest_stree_id(tmp
),
358 highest_stree_id(gate_sm
));
362 filtered_sm
= filter_pools(tmp
, remove_stack
, keep_stack
, &modified
);
363 if (filtered_sm
&& modified
) {
364 /* the assignments here are for borrowed implications */
365 filtered_sm
->name
= tmp
->name
;
366 filtered_sm
->sym
= tmp
->sym
;
367 avl_insert(&ret
, filtered_sm
);
372 } END_FOR_EACH_SM(tmp
);
376 static void separate_and_filter(struct sm_state
*sm_state
, int comparison
, struct range_list
*vals
,
378 struct stree
*pre_stree
,
379 struct stree
**true_states
,
380 struct stree
**false_states
)
382 struct stree_stack
*true_stack
= NULL
;
383 struct stree_stack
*false_stack
= NULL
;
384 struct timeval time_before
;
385 struct timeval time_after
;
387 gettimeofday(&time_before
, NULL
);
389 if (!is_merged(sm_state
)) {
390 DIMPLIED("%d '%s' is not merged.\n", get_lineno(), sm_state
->name
);
394 if (option_debug_implied
|| option_debug
) {
396 sm_msg("checking implications: (%s %s %s)",
397 sm_state
->name
, show_special(comparison
), show_rl(vals
));
399 sm_msg("checking implications: (%s %s %s)",
400 show_rl(vals
), show_special(comparison
), sm_state
->name
);
403 separate_pools(sm_state
, comparison
, vals
, lr
, &true_stack
, &false_stack
, NULL
);
405 DIMPLIED("filtering true stack.\n");
406 *true_states
= filter_stack(sm_state
, pre_stree
, false_stack
, true_stack
);
407 DIMPLIED("filtering false stack.\n");
408 *false_states
= filter_stack(sm_state
, pre_stree
, true_stack
, false_stack
);
409 free_stree_stack(&true_stack
);
410 free_stree_stack(&false_stack
);
411 if (option_debug_implied
|| option_debug
) {
412 printf("These are the implied states for the true path:\n");
413 __print_stree(*true_states
);
414 printf("These are the implied states for the false path:\n");
415 __print_stree(*false_states
);
418 gettimeofday(&time_after
, NULL
);
419 if (time_after
.tv_sec
- time_before
.tv_sec
> 7)
420 __bail_on_rest_of_function
= 1;
423 static struct expression
*get_left_most_expr(struct expression
*expr
)
425 expr
= strip_expr(expr
);
426 if (expr
->type
== EXPR_ASSIGNMENT
)
427 return get_left_most_expr(expr
->left
);
431 static int is_merged_expr(struct expression
*expr
)
436 if (get_value(expr
, &dummy
))
438 sm
= get_sm_state_expr(SMATCH_EXTRA
, expr
);
446 static void delete_equiv_stree(struct stree
**stree
, const char *name
, struct symbol
*sym
)
448 struct smatch_state
*state
;
449 struct relation
*rel
;
451 state
= get_state(SMATCH_EXTRA
, name
, sym
);
452 if (!estate_related(state
)) {
453 delete_state_stree(stree
, SMATCH_EXTRA
, name
, sym
);
457 FOR_EACH_PTR(estate_related(state
), rel
) {
458 delete_state_stree(stree
, SMATCH_EXTRA
, rel
->name
, rel
->sym
);
459 } END_FOR_EACH_PTR(rel
);
462 static void handle_comparison(struct expression
*expr
,
463 struct stree
**implied_true
,
464 struct stree
**implied_false
)
466 struct sm_state
*sm
= NULL
;
467 struct range_list
*ranges
= NULL
;
468 struct expression
*left
;
469 struct expression
*right
;
472 left
= get_left_most_expr(expr
->left
);
473 right
= get_left_most_expr(expr
->right
);
475 if (is_merged_expr(left
)) {
477 sm
= get_sm_state_expr(SMATCH_EXTRA
, left
);
478 get_implied_rl(right
, &ranges
);
479 } else if (is_merged_expr(right
)) {
481 sm
= get_sm_state_expr(SMATCH_EXTRA
, right
);
482 get_implied_rl(left
, &ranges
);
485 if (!ranges
|| !sm
) {
490 separate_and_filter(sm
, expr
->op
, ranges
, lr
, __get_cur_stree(), implied_true
, implied_false
);
492 delete_equiv_stree(implied_true
, sm
->name
, sm
->sym
);
493 delete_equiv_stree(implied_false
, sm
->name
, sm
->sym
);
496 static void handle_zero_comparison(struct expression
*expr
,
497 struct stree
**implied_true
,
498 struct stree
**implied_false
)
504 if (expr
->type
== EXPR_POSTOP
)
505 expr
= strip_expr(expr
->unop
);
507 if (expr
->type
== EXPR_ASSIGNMENT
) {
508 /* most of the time ->pools will be empty here because we
509 just set the state, but if have assigned a conditional
510 function there are implications. */
514 name
= expr_to_var_sym(expr
, &sym
);
517 sm
= get_sm_state(SMATCH_EXTRA
, name
, sym
);
521 separate_and_filter(sm
, SPECIAL_NOTEQUAL
, tmp_range_list(0), LEFT
, __get_cur_stree(), implied_true
, implied_false
);
522 delete_equiv_stree(implied_true
, name
, sym
);
523 delete_equiv_stree(implied_false
, name
, sym
);
528 static int handled_by_implied_hook(struct expression
*expr
,
529 struct stree
**implied_true
,
530 struct stree
**implied_false
)
532 struct stree_stack
*true_stack
= NULL
;
533 struct stree_stack
*false_stack
= NULL
;
534 struct stree
*pre_stree
;
537 sm
= comparison_implication_hook(expr
, &true_stack
, &false_stack
);
541 pre_stree
= clone_stree(__get_cur_stree());
543 *implied_true
= filter_stack(sm
, pre_stree
, false_stack
, true_stack
);
544 *implied_false
= filter_stack(sm
, pre_stree
, true_stack
, false_stack
);
546 free_stree_stack(&true_stack
);
547 free_stree_stack(&false_stack
);
552 static void get_tf_states(struct expression
*expr
,
553 struct stree
**implied_true
,
554 struct stree
**implied_false
)
556 if (handled_by_implied_hook(expr
, implied_true
, implied_false
))
559 if (expr
->type
== EXPR_COMPARE
)
560 handle_comparison(expr
, implied_true
, implied_false
);
562 handle_zero_comparison(expr
, implied_true
, implied_false
);
565 static struct stree
*saved_implied_true
;
566 static struct stree
*saved_implied_false
;
568 static void save_implications_hook(struct expression
*expr
)
570 if (option_no_implied
)
572 get_tf_states(expr
, &saved_implied_true
, &saved_implied_false
);
575 static void set_implied_states(struct expression
*expr
)
579 FOR_EACH_SM(saved_implied_true
, sm
) {
580 __set_true_false_sm(sm
, NULL
);
581 } END_FOR_EACH_SM(sm
);
582 free_stree(&saved_implied_true
);
584 FOR_EACH_SM(saved_implied_false
, sm
) {
585 __set_true_false_sm(NULL
, sm
);
586 } END_FOR_EACH_SM(sm
);
587 free_stree(&saved_implied_false
);
590 struct range_list
*__get_implied_values(struct expression
*switch_expr
)
594 struct smatch_state
*state
;
595 struct range_list
*ret
= NULL
;
597 name
= expr_to_var_sym(switch_expr
, &sym
);
600 state
= get_state(SMATCH_EXTRA
, name
, sym
);
603 ret
= clone_rl(estate_rl(state
));
609 type
= get_type(switch_expr
);
610 ret
= alloc_rl(sval_type_min(type
), sval_type_max(type
));
615 struct stree
*__implied_case_stree(struct expression
*switch_expr
,
616 struct expression
*case_expr
,
617 struct range_list_stack
**remaining_cases
,
618 struct stree
**raw_stree
)
623 struct stree
*true_states
= NULL
;
624 struct stree
*false_states
= NULL
;
625 struct stree
*extra_states
= NULL
;
626 struct stree
*ret
= clone_stree(*raw_stree
);
628 struct range_list
*vals
= NULL
;
630 name
= expr_to_var_sym(switch_expr
, &sym
);
633 sm
= get_sm_state_stree(*raw_stree
, SMATCH_EXTRA
, name
, sym
);
636 if (get_value(case_expr
, &sval
)) {
637 filter_top_rl(remaining_cases
, sval
);
638 add_range(&vals
, sval
, sval
);
640 vals
= clone_rl(top_rl(*remaining_cases
));
643 vals
= top_rl(*remaining_cases
);
647 separate_and_filter(sm
, SPECIAL_EQUAL
, vals
, LEFT
, *raw_stree
, &true_states
, &false_states
);
649 __push_fake_cur_stree();
651 set_extra_nomod(name
, sym
, alloc_estate_rl(vals
));
652 extra_states
= __pop_fake_cur_stree();
653 overwrite_stree(extra_states
, &true_states
);
654 overwrite_stree(true_states
, &ret
);
655 free_stree(&extra_states
);
656 free_stree(&true_states
);
657 free_stree(&false_states
);
663 static void match_end_func(struct symbol
*sym
)
667 implied_debug_msg
= NULL
;
670 static int sm_state_in_slist(struct sm_state
*sm
, struct state_list
*slist
)
672 struct sm_state
*tmp
;
674 FOR_EACH_PTR(slist
, tmp
) {
677 } END_FOR_EACH_PTR(tmp
);
682 * The situation is we have a SMATCH_EXTRA state and we want to break it into
683 * each of the ->possible states and find the implications of each. The caller
684 * has to use __push_fake_cur_stree() to preserve the correct states so they
685 * can be restored later.
687 void overwrite_states_using_pool(struct sm_state
*sm
)
689 struct sm_state
*old
;
690 struct sm_state
*new;
695 FOR_EACH_SM(sm
->pool
, old
) {
696 new = get_sm_state(old
->owner
, old
->name
, old
->sym
);
697 if (!new) /* the variable went out of scope */
699 if (sm_state_in_slist(old
, new->possible
))
700 set_state(old
->owner
, old
->name
, old
->sym
, old
->state
);
701 } END_FOR_EACH_SM(old
);
704 void __extra_match_condition(struct expression
*expr
);
705 void __comparison_match_condition(struct expression
*expr
);
706 void register_implications(int id
)
708 add_hook(&save_implications_hook
, CONDITION_HOOK
);
709 add_hook(&__extra_match_condition
, CONDITION_HOOK
);
710 add_hook(&__comparison_match_condition
, CONDITION_HOOK
);
711 add_hook(&set_implied_states
, CONDITION_HOOK
);
712 add_hook(&match_end_func
, END_FUNC_HOOK
);