2 * sparse/smatch_states.c
4 * Copyright (C) 2006 Dan Carpenter.
6 * Licensed under the Open Software License version 1.1
11 * You have a lists of states. kernel = locked, foo = NULL, ...
12 * When you hit an if {} else {} statement then you swap the list
13 * of states for a different list of states. The lists are stored
16 * At the beginning of this file there are list of the stacks that
17 * we use. Each function in this file does something to one of
20 * So the smatch_flow.c understands code but it doesn't understand states.
21 * smatch_flow calls functions in this file. This file calls functions
22 * in smatch_slist.c which just has boring generic plumbing for handling
23 * state lists. But really it's this file where all the magic happens.
29 #include "smatch_slist.h"
30 #include "smatch_extra.h"
32 struct smatch_state undefined
= { .name
= "undefined" };
33 struct smatch_state merged
= { .name
= "merged" };
34 struct smatch_state true_state
= { .name
= "true" };
35 struct smatch_state false_state
= { .name
= "false" };
37 static struct state_list
*cur_slist
; /* current states */
39 static struct state_list_stack
*true_stack
; /* states after a t/f branch */
40 static struct state_list_stack
*false_stack
;
41 static struct state_list_stack
*pre_cond_stack
; /* states before a t/f branch */
43 static struct state_list_stack
*cond_true_stack
; /* states affected by a branch */
44 static struct state_list_stack
*cond_false_stack
;
46 static struct state_list_stack
*fake_cur_slist_stack
;
48 static struct state_list_stack
*break_stack
;
49 static struct state_list_stack
*switch_stack
;
50 static struct range_list_stack
*remaining_cases
;
51 static struct state_list_stack
*default_stack
;
52 static struct state_list_stack
*continue_stack
;
54 static struct named_stack
*goto_stack
;
56 static struct ptr_list
*backup
;
58 struct state_list_stack
*implied_pools
;
62 void __print_cur_slist(void)
64 __print_slist(cur_slist
);
67 static int in_declarations_bit(void)
69 struct statement
*tmp
;
71 FOR_EACH_PTR_REVERSE(big_statement_stack
, tmp
) {
72 if (tmp
->type
== STMT_DECLARATION
)
75 } END_FOR_EACH_PTR_REVERSE(tmp
);
81 static int reset_warnings
= 1;
89 if (in_declarations_bit())
92 /* option spammy turns on a noisier version of this */
93 if (reset_warnings
&& !option_spammy
)
94 sm_msg("info: ignoring unreachable code.");
100 struct sm_state
*set_state(int owner
, const char *name
, struct symbol
*sym
, struct smatch_state
*state
)
102 struct sm_state
*ret
;
108 struct smatch_state
*s
;
110 s
= get_state(owner
, name
, sym
);
112 printf("%d new state. name='%s' [%s] %s\n",
113 get_lineno(), name
, check_name(owner
), show_state(state
));
115 printf("%d state change name='%s' [%s] %s => %s\n",
116 get_lineno(), name
, check_name(owner
), show_state(s
),
120 if (owner
!= -1 && unreachable())
123 if (fake_cur_slist_stack
)
124 set_state_stack(&fake_cur_slist_stack
, owner
, name
, sym
, state
);
126 ret
= set_state_slist(&cur_slist
, owner
, name
, sym
, state
);
128 if (cond_true_stack
) {
129 set_state_stack(&cond_true_stack
, owner
, name
, sym
, state
);
130 set_state_stack(&cond_false_stack
, owner
, name
, sym
, state
);
135 struct sm_state
*set_state_expr(int owner
, struct expression
*expr
, struct smatch_state
*state
)
139 struct sm_state
*ret
= NULL
;
141 expr
= strip_expr(expr
);
142 name
= expr_to_var_sym(expr
, &sym
);
145 ret
= set_state(owner
, name
, sym
, state
);
151 void __push_fake_cur_slist()
153 push_slist(&fake_cur_slist_stack
, NULL
);
154 __save_pre_cond_states();
157 struct state_list
*__pop_fake_cur_slist()
159 __use_pre_cond_states();
160 return pop_slist(&fake_cur_slist_stack
);
163 void __merge_slist_into_cur(struct state_list
*slist
)
166 struct sm_state
*orig
;
167 struct sm_state
*merged
;
169 FOR_EACH_PTR(slist
, sm
) {
170 orig
= get_sm_state(sm
->owner
, sm
->name
, sm
->sym
);
172 merged
= merge_sm_states(orig
, sm
);
176 } END_FOR_EACH_PTR(sm
);
179 void __set_sm(struct sm_state
*sm
)
182 struct smatch_state
*s
;
184 s
= get_state(sm
->owner
, sm
->name
, sm
->sym
);
186 printf("%d new state. name='%s' [%s] %s\n",
187 get_lineno(), sm
->name
, check_name(sm
->owner
),
188 show_state(sm
->state
));
190 printf("%d state change name='%s' [%s] %s => %s\n",
191 get_lineno(), sm
->name
, check_name(sm
->owner
), show_state(s
),
192 show_state(sm
->state
));
198 if (fake_cur_slist_stack
)
199 overwrite_sm_state_stack(&fake_cur_slist_stack
, sm
);
201 overwrite_sm_state(&cur_slist
, sm
);
203 if (cond_true_stack
) {
204 overwrite_sm_state_stack(&cond_true_stack
, sm
);
205 overwrite_sm_state_stack(&cond_false_stack
, sm
);
209 struct smatch_state
*get_state(int owner
, const char *name
, struct symbol
*sym
)
211 return get_state_slist(cur_slist
, owner
, name
, sym
);
214 struct smatch_state
*get_state_expr(int owner
, struct expression
*expr
)
218 struct smatch_state
*ret
= NULL
;
220 expr
= strip_expr(expr
);
221 name
= expr_to_var_sym(expr
, &sym
);
224 ret
= get_state(owner
, name
, sym
);
230 struct state_list
*get_possible_states(int owner
, const char *name
, struct symbol
*sym
)
232 struct sm_state
*sms
;
234 sms
= get_sm_state_slist(cur_slist
, owner
, name
, sym
);
236 return sms
->possible
;
240 struct state_list
*get_possible_states_expr(int owner
, struct expression
*expr
)
244 struct state_list
*ret
= NULL
;
246 expr
= strip_expr(expr
);
247 name
= expr_to_var_sym(expr
, &sym
);
250 ret
= get_possible_states(owner
, name
, sym
);
256 struct sm_state
*get_sm_state(int owner
, const char *name
, struct symbol
*sym
)
258 return get_sm_state_slist(cur_slist
, owner
, name
, sym
);
261 struct sm_state
*get_sm_state_expr(int owner
, struct expression
*expr
)
265 struct sm_state
*ret
= NULL
;
267 expr
= strip_expr(expr
);
268 name
= expr_to_var_sym(expr
, &sym
);
271 ret
= get_sm_state(owner
, name
, sym
);
277 void delete_state(int owner
, const char *name
, struct symbol
*sym
)
279 delete_state_slist(&cur_slist
, owner
, name
, sym
);
280 if (cond_true_stack
) {
281 delete_state_stack(&pre_cond_stack
, owner
, name
, sym
);
282 delete_state_stack(&cond_true_stack
, owner
, name
, sym
);
283 delete_state_stack(&cond_false_stack
, owner
, name
, sym
);
287 void delete_state_expr(int owner
, struct expression
*expr
)
292 expr
= strip_expr(expr
);
293 name
= expr_to_var_sym(expr
, &sym
);
296 delete_state(owner
, name
, sym
);
301 struct state_list
*get_all_states_slist(int owner
, struct state_list
*source
)
303 struct state_list
*slist
= NULL
;
304 struct sm_state
*tmp
;
306 FOR_EACH_PTR(source
, tmp
) {
307 if (tmp
->owner
== owner
)
308 add_ptr_list(&slist
, tmp
);
309 } END_FOR_EACH_PTR(tmp
);
314 struct state_list
*get_all_states(int owner
)
316 struct state_list
*slist
= NULL
;
317 struct sm_state
*tmp
;
319 FOR_EACH_PTR(cur_slist
, tmp
) {
320 if (tmp
->owner
== owner
)
321 add_ptr_list(&slist
, tmp
);
322 } END_FOR_EACH_PTR(tmp
);
327 int is_reachable(void)
334 struct state_list
*__get_cur_slist(void)
339 void set_true_false_states(int owner
, const char *name
, struct symbol
*sym
,
340 struct smatch_state
*true_state
,
341 struct smatch_state
*false_state
)
344 struct smatch_state
*tmp
;
346 tmp
= get_state(owner
, name
, sym
);
347 sm_debug("%d set_true_false '%s'. Was %s. Now T:%s F:%s\n",
348 get_lineno(), name
, show_state(tmp
),
349 show_state(true_state
), show_state(false_state
));
355 if (!cond_false_stack
|| !cond_true_stack
) {
356 printf("Error: missing true/false stacks\n");
361 set_state_slist(&cur_slist
, owner
, name
, sym
, true_state
);
362 set_state_stack(&cond_true_stack
, owner
, name
, sym
, true_state
);
365 set_state_stack(&cond_false_stack
, owner
, name
, sym
, false_state
);
368 void set_true_false_states_expr(int owner
, struct expression
*expr
,
369 struct smatch_state
*true_state
,
370 struct smatch_state
*false_state
)
375 expr
= strip_expr(expr
);
376 name
= expr_to_var_sym(expr
, &sym
);
379 set_true_false_states(owner
, name
, sym
, true_state
, false_state
);
384 void __set_true_false_sm(struct sm_state
*true_sm
, struct sm_state
*false_sm
)
389 if (!cond_false_stack
|| !cond_true_stack
) {
390 printf("Error: missing true/false stacks\n");
395 overwrite_sm_state(&cur_slist
, true_sm
);
396 overwrite_sm_state_stack(&cond_true_stack
, true_sm
);
399 overwrite_sm_state_stack(&cond_false_stack
, false_sm
);
402 void nullify_path(void)
404 free_slist(&cur_slist
);
407 void __match_nullify_path_hook(const char *fn
, struct expression
*expr
,
414 * At the start of every function we mark the path
415 * as unnull. That way there is always at least one state
416 * in the cur_slist until nullify_path is called. This
417 * is used in merge_slist() for the first null check.
419 void __unnullify_path(void)
421 set_state(-1, "unnull_path", NULL
, &true_state
);
424 int __path_is_null(void)
431 static void check_stack_free(struct state_list_stack
**stack
)
434 sm_msg("smatch internal error: stack not empty");
435 free_stack_and_slists(stack
);
439 void save_all_states(void)
441 __add_ptr_list(&backup
, cur_slist
, 0);
443 __add_ptr_list(&backup
, true_stack
, 0);
444 __add_ptr_list(&backup
, false_stack
, 0);
445 __add_ptr_list(&backup
, pre_cond_stack
, 0);
447 __add_ptr_list(&backup
, cond_true_stack
, 0);
448 __add_ptr_list(&backup
, cond_false_stack
, 0);
450 __add_ptr_list(&backup
, fake_cur_slist_stack
, 0);
452 __add_ptr_list(&backup
, break_stack
, 0);
453 __add_ptr_list(&backup
, switch_stack
, 0);
454 __add_ptr_list(&backup
, remaining_cases
, 0);
455 __add_ptr_list(&backup
, default_stack
, 0);
456 __add_ptr_list(&backup
, continue_stack
, 0);
458 __add_ptr_list(&backup
, goto_stack
, 0);
461 void nullify_all_states(void)
467 pre_cond_stack
= NULL
;
469 cond_true_stack
= NULL
;
470 cond_false_stack
= NULL
;
472 fake_cur_slist_stack
= NULL
;
476 remaining_cases
= NULL
;
477 default_stack
= NULL
;
478 continue_stack
= NULL
;
483 static void *pop_backup(void)
487 ret
= last_ptr_list(backup
);
488 delete_ptr_list_last(&backup
);
492 void restore_all_states(void)
494 goto_stack
= pop_backup();
496 continue_stack
= pop_backup();
497 default_stack
= pop_backup();
498 remaining_cases
= pop_backup();
499 switch_stack
= pop_backup();
500 break_stack
= pop_backup();
502 fake_cur_slist_stack
= pop_backup();
504 cond_false_stack
= pop_backup();
505 cond_true_stack
= pop_backup();
507 pre_cond_stack
= pop_backup();
508 false_stack
= pop_backup();
509 true_stack
= pop_backup();
511 cur_slist
= pop_backup();
514 void clear_all_states(void)
516 struct named_slist
*named_slist
;
519 check_stack_free(&true_stack
);
520 check_stack_free(&false_stack
);
521 check_stack_free(&pre_cond_stack
);
522 check_stack_free(&cond_true_stack
);
523 check_stack_free(&cond_false_stack
);
524 check_stack_free(&break_stack
);
525 check_stack_free(&switch_stack
);
526 check_stack_free(&continue_stack
);
527 free_stack_and_slists(&implied_pools
);
529 FOR_EACH_PTR(goto_stack
, named_slist
) {
530 free_slist(&named_slist
->slist
);
531 } END_FOR_EACH_PTR(named_slist
);
532 __free_ptr_list((struct ptr_list
**)&goto_stack
);
533 free_every_single_sm_state();
536 void __push_cond_stacks(void)
538 push_slist(&cond_true_stack
, NULL
);
539 push_slist(&cond_false_stack
, NULL
);
542 struct state_list
*__copy_cond_true_states(void)
544 struct state_list
*ret
;
546 ret
= pop_slist(&cond_true_stack
);
547 push_slist(&cond_true_stack
, clone_slist(ret
));
551 struct state_list
*__copy_cond_false_states(void)
553 struct state_list
*ret
;
555 ret
= pop_slist(&cond_false_stack
);
556 push_slist(&cond_false_stack
, clone_slist(ret
));
560 struct state_list
*__pop_cond_true_stack(void)
562 return pop_slist(&cond_true_stack
);
565 struct state_list
*__pop_cond_false_stack(void)
567 return pop_slist(&cond_false_stack
);
571 * This combines the pre cond states with either the true or false states.
573 * a = kmalloc() ; if (a !! foo(a)
574 * In the pre state a is possibly null. In the true state it is non null.
575 * In the false state it is null. Combine the pre and the false to get
576 * that when we call 'foo', 'a' is null.
578 static void __use_cond_stack(struct state_list_stack
**stack
)
580 struct state_list
*slist
;
582 free_slist(&cur_slist
);
584 cur_slist
= pop_slist(&pre_cond_stack
);
585 push_slist(&pre_cond_stack
, clone_slist(cur_slist
));
587 slist
= pop_slist(stack
);
588 overwrite_slist(slist
, &cur_slist
);
589 push_slist(stack
, slist
);
592 void __use_pre_cond_states(void)
594 free_slist(&cur_slist
);
595 cur_slist
= pop_slist(&pre_cond_stack
);
598 void __use_cond_true_states(void)
600 __use_cond_stack(&cond_true_stack
);
603 void __use_cond_false_states(void)
605 __use_cond_stack(&cond_false_stack
);
608 void __negate_cond_stacks(void)
610 struct state_list
*old_false
, *old_true
;
612 __use_cond_stack(&cond_false_stack
);
613 old_false
= pop_slist(&cond_false_stack
);
614 old_true
= pop_slist(&cond_true_stack
);
615 push_slist(&cond_false_stack
, old_true
);
616 push_slist(&cond_true_stack
, old_false
);
619 void __and_cond_states(void)
621 and_slist_stack(&cond_true_stack
);
622 or_slist_stack(&pre_cond_stack
, cur_slist
, &cond_false_stack
);
625 void __or_cond_states(void)
627 or_slist_stack(&pre_cond_stack
, cur_slist
, &cond_true_stack
);
628 and_slist_stack(&cond_false_stack
);
631 void __save_pre_cond_states(void)
633 push_slist(&pre_cond_stack
, clone_slist(cur_slist
));
636 void __discard_pre_cond_states(void)
638 struct state_list
*tmp
;
640 tmp
= pop_slist(&pre_cond_stack
);
644 void __use_cond_states(void)
646 struct state_list
*pre
, *pre_clone
, *true_states
, *false_states
;
648 pre
= pop_slist(&pre_cond_stack
);
649 pre_clone
= clone_slist(pre
);
651 true_states
= pop_slist(&cond_true_stack
);
652 overwrite_slist(true_states
, &pre
);
653 /* we use the true states right away */
654 free_slist(&cur_slist
);
657 false_states
= pop_slist(&cond_false_stack
);
658 overwrite_slist(false_states
, &pre_clone
);
659 push_slist(&false_stack
, pre_clone
);
662 void __push_true_states(void)
664 push_slist(&true_stack
, clone_slist(cur_slist
));
667 void __use_false_states(void)
669 free_slist(&cur_slist
);
670 cur_slist
= pop_slist(&false_stack
);
673 void __discard_false_states(void)
675 struct state_list
*slist
;
677 slist
= pop_slist(&false_stack
);
681 void __merge_false_states(void)
683 struct state_list
*slist
;
685 slist
= pop_slist(&false_stack
);
686 merge_slist(&cur_slist
, slist
);
690 void __merge_true_states(void)
692 struct state_list
*slist
;
694 slist
= pop_slist(&true_stack
);
695 merge_slist(&cur_slist
, slist
);
699 void __push_continues(void)
701 push_slist(&continue_stack
, NULL
);
704 void __discard_continues(void)
706 struct state_list
*slist
;
708 slist
= pop_slist(&continue_stack
);
712 void __process_continues(void)
714 struct state_list
*slist
;
716 slist
= pop_slist(&continue_stack
);
718 slist
= clone_slist(cur_slist
);
720 merge_slist(&slist
, cur_slist
);
722 push_slist(&continue_stack
, slist
);
725 static int top_slist_empty(struct state_list_stack
**stack
)
727 struct state_list
*tmp
;
730 tmp
= pop_slist(stack
);
733 push_slist(stack
, tmp
);
737 /* a silly loop does this: while(i--) { return; } */
738 void __warn_on_silly_pre_loops(void)
740 if (!__path_is_null())
742 if (!top_slist_empty(&continue_stack
))
744 if (!top_slist_empty(&break_stack
))
746 /* if the path was nullified before the loop, then we already
747 printed an error earlier */
748 if (top_slist_empty(&false_stack
))
750 sm_msg("info: loop could be replaced with if statement.");
753 void __merge_continues(void)
755 struct state_list
*slist
;
757 slist
= pop_slist(&continue_stack
);
758 merge_slist(&cur_slist
, slist
);
762 void __push_breaks(void)
764 push_slist(&break_stack
, NULL
);
767 void __process_breaks(void)
769 struct state_list
*slist
;
771 slist
= pop_slist(&break_stack
);
773 slist
= clone_slist(cur_slist
);
775 merge_slist(&slist
, cur_slist
);
777 push_slist(&break_stack
, slist
);
780 int __has_breaks(void)
782 struct state_list
*slist
;
785 slist
= pop_slist(&break_stack
);
787 push_slist(&break_stack
, slist
);
791 void __merge_breaks(void)
793 struct state_list
*slist
;
795 slist
= pop_slist(&break_stack
);
796 merge_slist(&cur_slist
, slist
);
800 void __use_breaks(void)
802 free_slist(&cur_slist
);
803 cur_slist
= pop_slist(&break_stack
);
806 void __save_switch_states(struct expression
*switch_expr
)
808 push_rl(&remaining_cases
, __get_implied_values(switch_expr
));
809 push_slist(&switch_stack
, clone_slist(cur_slist
));
812 void __merge_switches(struct expression
*switch_expr
, struct expression
*case_expr
)
814 struct state_list
*slist
;
815 struct state_list
*implied_slist
;
817 slist
= pop_slist(&switch_stack
);
818 implied_slist
= __implied_case_slist(switch_expr
, case_expr
, &remaining_cases
, &slist
);
819 merge_slist(&cur_slist
, implied_slist
);
820 free_slist(&implied_slist
);
821 push_slist(&switch_stack
, slist
);
824 void __discard_switches(void)
826 struct state_list
*slist
;
828 pop_rl(&remaining_cases
);
829 slist
= pop_slist(&switch_stack
);
833 void __push_default(void)
835 push_slist(&default_stack
, NULL
);
838 void __set_default(void)
840 set_state_stack(&default_stack
, 0, "has_default", NULL
, &true_state
);
843 int __pop_default(void)
845 struct state_list
*slist
;
847 slist
= pop_slist(&default_stack
);
855 static struct named_slist
*alloc_named_slist(const char *name
, struct state_list
*slist
)
857 struct named_slist
*named_slist
= __alloc_named_slist(0);
859 named_slist
->name
= (char *)name
;
860 named_slist
->slist
= slist
;
864 void __save_gotos(const char *name
)
866 struct state_list
**slist
;
867 struct state_list
*clone
;
869 slist
= get_slist_from_named_stack(goto_stack
, name
);
871 clone
= clone_slist(cur_slist
);
872 merge_slist(slist
, clone
);
876 struct named_slist
*named_slist
;
878 clone
= clone_slist(cur_slist
);
879 named_slist
= alloc_named_slist(name
, clone
);
880 add_ptr_list(&goto_stack
, named_slist
);
884 void __merge_gotos(const char *name
)
886 struct state_list
**slist
;
888 slist
= get_slist_from_named_stack(goto_stack
, name
);
890 merge_slist(&cur_slist
, *slist
);