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.
30 #include "smatch_slist.h"
31 #include "smatch_extra.h"
33 struct smatch_state undefined
= { .name
= "undefined" };
34 struct smatch_state merged
= { .name
= "merged" };
35 struct smatch_state true_state
= { .name
= "true" };
36 struct smatch_state false_state
= { .name
= "false" };
38 static struct state_list
*cur_slist
; /* current states */
40 static struct state_list_stack
*true_stack
; /* states after a t/f branch */
41 static struct state_list_stack
*false_stack
;
42 static struct state_list_stack
*pre_cond_stack
; /* states before a t/f branch */
44 static struct state_list_stack
*cond_true_stack
; /* states affected by a branch */
45 static struct state_list_stack
*cond_false_stack
;
48 struct state_list
*__fake_cur_slist
= NULL
;
49 int __fake_conditions
= 0;
50 struct state_list
*__fake_cond_true
= NULL
;
51 struct state_list
*__fake_cond_false
= NULL
;
53 static struct state_list_stack
*break_stack
;
54 static struct state_list_stack
*switch_stack
;
55 static struct range_list_stack
*remaining_cases
;
56 static struct state_list_stack
*default_stack
;
57 static struct state_list_stack
*continue_stack
;
59 static struct named_stack
*goto_stack
;
61 struct state_list_stack
*implied_pools
;
65 void __print_cur_slist(void)
67 __print_slist(cur_slist
);
70 static int in_declarations_bit(void)
72 struct statement
*tmp
;
74 FOR_EACH_PTR_REVERSE(big_statement_stack
, tmp
) {
75 if (tmp
->type
== STMT_DECLARATION
)
78 } END_FOR_EACH_PTR_REVERSE(tmp
);
84 static int reset_warnings
= 1;
91 if (in_declarations_bit())
94 /* option spammy turns on a noisier version of this */
95 if (reset_warnings
&& !option_spammy
)
96 sm_msg("info: ignoring unreachable code.");
101 void set_state(int owner
, const char *name
, struct symbol
*sym
,
102 struct smatch_state
*state
)
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 __use_default_modification_hook(owner
, name
);
126 set_state_slist(&__fake_cur_slist
, owner
, name
, sym
, state
);
130 set_state_slist(&cur_slist
, owner
, name
, sym
, state
);
132 if (cond_true_stack
) {
133 set_state_stack(&cond_true_stack
, owner
, name
, sym
, state
);
134 set_state_stack(&cond_false_stack
, owner
, name
, sym
, state
);
138 void set_state_expr(int owner
, struct expression
*expr
,
139 struct smatch_state
*state
)
144 expr
= strip_expr(expr
);
145 name
= get_variable_from_expr(expr
, &sym
);
148 set_state(owner
, name
, sym
, state
);
154 void __set_state(struct sm_state
*sm
)
157 struct smatch_state
*s
;
159 s
= get_state(sm
->owner
, sm
->name
, sm
->sym
);
161 printf("%d new state. name='%s' [%s] %s\n",
162 get_lineno(), sm
->name
, check_name(sm
->owner
),
163 show_state(sm
->state
));
165 printf("%d state change name='%s' [%s] %s => %s\n",
166 get_lineno(), sm
->name
, check_name(sm
->owner
), show_state(s
),
167 show_state(sm
->state
));
173 overwrite_sm_state(&cur_slist
, sm
);
175 if (cond_true_stack
) {
176 overwrite_sm_state_stack(&cond_true_stack
, sm
);
177 overwrite_sm_state_stack(&cond_false_stack
, sm
);
181 struct smatch_state
*get_state(int owner
, const char *name
, struct symbol
*sym
)
183 return get_state_slist(cur_slist
, owner
, name
, sym
);
186 struct smatch_state
*get_state_expr(int owner
, struct expression
*expr
)
190 struct smatch_state
*ret
= NULL
;
192 expr
= strip_expr(expr
);
193 name
= get_variable_from_expr(expr
, &sym
);
196 ret
= get_state(owner
, name
, sym
);
202 struct state_list
*get_possible_states(int owner
, const char *name
,
205 struct sm_state
*sms
;
207 sms
= get_sm_state_slist(cur_slist
, owner
, name
, sym
);
209 return sms
->possible
;
213 struct state_list
*get_possible_states_expr(int owner
, struct expression
*expr
)
217 struct state_list
*ret
= NULL
;
219 expr
= strip_expr(expr
);
220 name
= get_variable_from_expr(expr
, &sym
);
223 ret
= get_possible_states(owner
, name
, sym
);
229 struct sm_state
*get_sm_state(int owner
, const char *name
, struct symbol
*sym
)
231 return get_sm_state_slist(cur_slist
, owner
, name
, sym
);
234 struct sm_state
*get_sm_state_expr(int owner
, struct expression
*expr
)
238 struct sm_state
*ret
= NULL
;
240 expr
= strip_expr(expr
);
241 name
= get_variable_from_expr(expr
, &sym
);
244 ret
= get_sm_state(owner
, name
, sym
);
250 void delete_state(int owner
, const char *name
, struct symbol
*sym
)
252 delete_state_slist(&cur_slist
, owner
, name
, sym
);
253 if (cond_true_stack
) {
254 delete_state_stack(&pre_cond_stack
, owner
, name
, sym
);
255 delete_state_stack(&cond_true_stack
, owner
, name
, sym
);
256 delete_state_stack(&cond_false_stack
, owner
, name
, sym
);
260 void delete_state_expr(int owner
, struct expression
*expr
)
265 expr
= strip_expr(expr
);
266 name
= get_variable_from_expr(expr
, &sym
);
269 delete_state(owner
, name
, sym
);
274 struct state_list
*get_all_states(int owner
)
276 struct state_list
*slist
= NULL
;
277 struct sm_state
*tmp
;
279 FOR_EACH_PTR(cur_slist
, tmp
) {
280 if (tmp
->owner
== owner
) {
281 add_ptr_list(&slist
, tmp
);
283 } END_FOR_EACH_PTR(tmp
);
288 int is_reachable(void)
295 struct state_list
*__get_cur_slist(void)
300 void set_true_false_states(int owner
, const char *name
, struct symbol
*sym
,
301 struct smatch_state
*true_state
,
302 struct smatch_state
*false_state
)
305 struct smatch_state
*tmp
;
307 tmp
= get_state(owner
, name
, sym
);
308 sm_debug("%d set_true_false '%s'. Was %s. Now T:%s F:%s\n",
309 get_lineno(), name
, show_state(tmp
),
310 show_state(true_state
), show_state(false_state
));
316 if (__fake_conditions
) {
318 set_state_slist(&__fake_cond_true
, owner
, name
, sym
, true_state
);
320 set_state_slist(&__fake_cond_false
, owner
, name
, sym
, false_state
);
324 if (!cond_false_stack
|| !cond_true_stack
) {
325 printf("Error: missing true/false stacks\n");
330 set_state_slist(&cur_slist
, owner
, name
, sym
, true_state
);
331 set_state_stack(&cond_true_stack
, owner
, name
, sym
, true_state
);
334 set_state_stack(&cond_false_stack
, owner
, name
, sym
, false_state
);
337 void set_true_false_states_expr(int owner
, struct expression
*expr
,
338 struct smatch_state
*true_state
,
339 struct smatch_state
*false_state
)
344 expr
= strip_expr(expr
);
345 name
= get_variable_from_expr(expr
, &sym
);
348 set_true_false_states(owner
, name
, sym
, true_state
, false_state
);
353 void __set_true_false_sm(struct sm_state
*true_state
,
354 struct sm_state
*false_state
)
359 if (!cond_false_stack
|| !cond_true_stack
) {
360 printf("Error: missing true/false stacks\n");
365 overwrite_sm_state(&cur_slist
, true_state
);
366 overwrite_sm_state_stack(&cond_true_stack
, true_state
);
369 overwrite_sm_state_stack(&cond_false_stack
, false_state
);
372 void nullify_path(void)
374 free_slist(&cur_slist
);
377 void __match_nullify_path_hook(const char *fn
, struct expression
*expr
,
383 * At the start of every function we mark the path
384 * as unnull. That there is always at least one state
385 * in the cur_slist until nullify_path is called. This
386 * is used in merge_slist() for the first null check.
389 void __unnullify_path(void)
391 set_state(-1, "unnull_path", NULL
, &true_state
);
394 int __path_is_null(void)
401 void clear_all_states(void)
403 struct named_slist
*named_slist
;
406 free_stack_and_slists(&true_stack
);
407 free_stack_and_slists(&false_stack
);
408 free_stack_and_slists(&pre_cond_stack
);
409 free_stack_and_slists(&cond_true_stack
);
410 free_stack_and_slists(&cond_false_stack
);
411 free_stack_and_slists(&break_stack
);
412 free_stack_and_slists(&switch_stack
);
413 free_stack_and_slists(&continue_stack
);
414 free_stack_and_slists(&implied_pools
);
416 FOR_EACH_PTR(goto_stack
, named_slist
) {
417 free_slist(&named_slist
->slist
);
418 } END_FOR_EACH_PTR(named_slist
);
419 __free_ptr_list((struct ptr_list
**)&goto_stack
);
420 free_every_single_sm_state();
424 void __push_cond_stacks(void)
426 push_slist(&cond_true_stack
, NULL
);
427 push_slist(&cond_false_stack
, NULL
);
431 * This combines the pre cond states with either the true or false states.
433 * a = kmalloc() ; if (a !! foo(a)
434 * In the pre state a is possibly null. In the true state it is non null.
435 * In the false state it is null. Combine the pre and the false to get
436 * that when we call 'foo', 'a' is null.
439 static void __use_cond_stack(struct state_list_stack
**stack
)
441 struct state_list
*slist
;
443 free_slist(&cur_slist
);
445 cur_slist
= pop_slist(&pre_cond_stack
);
446 push_slist(&pre_cond_stack
, clone_slist(cur_slist
));
448 slist
= pop_slist(stack
);
449 overwrite_slist(slist
, &cur_slist
);
450 push_slist(stack
, slist
);
453 void __save_false_states_for_later(void)
455 struct state_list
*pre_conditions
;
456 struct state_list
*false_states
;
457 struct state_list
*tmp
;
459 pre_conditions
= pop_slist(&pre_cond_stack
);
460 false_states
= pop_slist(&cond_false_stack
);
461 tmp
= clone_slist(pre_conditions
);
463 overwrite_slist(false_states
, &tmp
);
465 push_slist(&pre_cond_stack
, tmp
);
466 push_slist(&pre_cond_stack
, pre_conditions
);
467 push_slist(&cond_false_stack
, false_states
);
470 void __use_previously_stored_false_states(void)
472 free_slist(&cur_slist
);
473 cur_slist
= pop_slist(&pre_cond_stack
);
476 void __use_cond_true_states(void)
478 __use_cond_stack(&cond_true_stack
);
481 void __use_cond_false_states(void)
483 __use_cond_stack(&cond_false_stack
);
486 void __negate_cond_stacks(void)
488 struct state_list
*old_false
, *old_true
;
490 __use_cond_stack(&cond_false_stack
);
491 old_false
= pop_slist(&cond_false_stack
);
492 old_true
= pop_slist(&cond_true_stack
);
493 push_slist(&cond_false_stack
, old_true
);
494 push_slist(&cond_true_stack
, old_false
);
497 void __and_cond_states(void)
499 and_slist_stack(&cond_true_stack
);
500 or_slist_stack(&pre_cond_stack
, cur_slist
, &cond_false_stack
);
503 void __or_cond_states(void)
505 or_slist_stack(&pre_cond_stack
, cur_slist
, &cond_true_stack
);
506 and_slist_stack(&cond_false_stack
);
509 void __save_pre_cond_states(void)
511 push_slist(&pre_cond_stack
, clone_slist(cur_slist
));
514 void __pop_pre_cond_states(void)
516 struct state_list
*tmp
;
518 tmp
= pop_slist(&pre_cond_stack
);
522 void __use_cond_states(void)
524 struct state_list
*pre
, *pre_clone
, *true_states
, *false_states
;
526 pre
= pop_slist(&pre_cond_stack
);
527 pre_clone
= clone_slist(pre
);
529 true_states
= pop_slist(&cond_true_stack
);
530 overwrite_slist(true_states
, &pre
);
531 /* we use the true states right away */
532 free_slist(&cur_slist
);
536 false_states
= pop_slist(&cond_false_stack
);
537 overwrite_slist(false_states
, &pre_clone
);
538 push_slist(&false_stack
, pre_clone
);
541 void __push_true_states(void)
543 push_slist(&true_stack
, clone_slist(cur_slist
));
546 void __use_false_states(void)
548 free_slist(&cur_slist
);
549 cur_slist
= pop_slist(&false_stack
);
552 void __pop_false_states(void)
554 struct state_list
*slist
;
556 slist
= pop_slist(&false_stack
);
560 void __merge_false_states(void)
562 struct state_list
*slist
;
564 slist
= pop_slist(&false_stack
);
565 merge_slist(&cur_slist
, slist
);
569 void __merge_true_states(void)
571 struct state_list
*slist
;
573 slist
= pop_slist(&true_stack
);
574 merge_slist(&cur_slist
, slist
);
578 void __push_continues(void)
580 push_slist(&continue_stack
, NULL
);
583 void __pop_continues(void)
585 struct state_list
*slist
;
587 slist
= pop_slist(&continue_stack
);
591 void __process_continues(void)
593 struct state_list
*slist
;
595 slist
= pop_slist(&continue_stack
);
597 slist
= clone_slist(cur_slist
);
599 merge_slist(&slist
, cur_slist
);
601 push_slist(&continue_stack
, slist
);
604 static int top_slist_empty(struct state_list_stack
**stack
)
606 struct state_list
*tmp
;
609 tmp
= pop_slist(stack
);
612 push_slist(stack
, tmp
);
616 /* a silly loop does this: while(i--) { return; } */
617 void __warn_on_silly_pre_loops(void)
619 if (!__path_is_null())
621 if (!top_slist_empty(&continue_stack
))
623 if (!top_slist_empty(&break_stack
))
625 /* if the path was nullified before the loop, then we already
626 printed an error earlier */
627 if (top_slist_empty(&false_stack
))
629 sm_msg("info: loop could be replaced with if statement.");
632 void __merge_continues(void)
634 struct state_list
*slist
;
636 slist
= pop_slist(&continue_stack
);
637 merge_slist(&cur_slist
, slist
);
641 void __push_breaks(void)
643 push_slist(&break_stack
, NULL
);
646 void __process_breaks(void)
648 struct state_list
*slist
;
650 slist
= pop_slist(&break_stack
);
652 slist
= clone_slist(cur_slist
);
654 merge_slist(&slist
, cur_slist
);
656 push_slist(&break_stack
, slist
);
659 void __merge_breaks(void)
661 struct state_list
*slist
;
663 slist
= pop_slist(&break_stack
);
664 merge_slist(&cur_slist
, slist
);
668 void __use_breaks(void)
670 free_slist(&cur_slist
);
671 cur_slist
= pop_slist(&break_stack
);
674 void __save_switch_states(struct expression
*switch_expr
)
676 push_range_list(&remaining_cases
, __get_implied_values(switch_expr
));
677 push_slist(&switch_stack
, clone_slist(cur_slist
));
680 void __merge_switches(struct expression
*switch_expr
, struct expression
*case_expr
)
682 struct state_list
*slist
;
683 struct state_list
*implied_slist
;
685 slist
= pop_slist(&switch_stack
);
686 implied_slist
= __implied_case_slist(switch_expr
, case_expr
, &remaining_cases
, &slist
);
687 merge_slist(&cur_slist
, implied_slist
);
688 free_slist(&implied_slist
);
689 push_slist(&switch_stack
, slist
);
692 void __pop_switches(void)
694 struct state_list
*slist
;
696 pop_range_list(&remaining_cases
);
697 slist
= pop_slist(&switch_stack
);
701 void __push_default(void)
703 push_slist(&default_stack
, NULL
);
706 void __set_default(void)
708 set_state_stack(&default_stack
, 0, "has_default", NULL
, &true_state
);
711 int __pop_default(void)
713 struct state_list
*slist
;
715 slist
= pop_slist(&default_stack
);
723 static struct named_slist
*alloc_named_slist(const char *name
,
724 struct state_list
*slist
)
726 struct named_slist
*named_slist
= __alloc_named_slist(0);
728 named_slist
->name
= (char *)name
;
729 named_slist
->slist
= slist
;
733 void __save_gotos(const char *name
)
735 struct state_list
**slist
;
736 struct state_list
*clone
;
738 slist
= get_slist_from_named_stack(goto_stack
, name
);
740 clone
= clone_slist(cur_slist
);
741 merge_slist(slist
, clone
);
745 struct named_slist
*named_slist
;
747 clone
= clone_slist(cur_slist
);
748 named_slist
= alloc_named_slist(name
, clone
);
749 add_ptr_list(&goto_stack
, named_slist
);
753 void __merge_gotos(const char *name
)
755 struct state_list
**slist
;
757 slist
= get_slist_from_named_stack(goto_stack
, name
);
759 merge_slist(&cur_slist
, *slist
);