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 struct state_list_stack
*implied_pools
;
60 void __print_cur_slist(void)
62 __print_slist(cur_slist
);
65 static int in_declarations_bit(void)
67 struct statement
*tmp
;
69 FOR_EACH_PTR_REVERSE(big_statement_stack
, tmp
) {
70 if (tmp
->type
== STMT_DECLARATION
)
73 } END_FOR_EACH_PTR_REVERSE(tmp
);
79 static int reset_warnings
= 1;
86 if (in_declarations_bit())
89 /* option spammy turns on a noisier version of this */
90 if (reset_warnings
&& !option_spammy
)
91 sm_msg("info: ignoring unreachable code.");
96 struct sm_state
*set_state(int owner
, const char *name
, struct symbol
*sym
, struct smatch_state
*state
)
104 struct smatch_state
*s
;
106 s
= get_state(owner
, name
, sym
);
108 printf("%d new state. name='%s' [%s] %s\n",
109 get_lineno(), name
, check_name(owner
), show_state(state
));
111 printf("%d state change name='%s' [%s] %s => %s\n",
112 get_lineno(), name
, check_name(owner
), show_state(s
),
116 if (owner
!= -1 && unreachable())
119 __use_default_modification_hook(owner
, name
);
121 if (fake_cur_slist_stack
)
122 set_state_stack(&fake_cur_slist_stack
, owner
, name
, sym
, state
);
124 ret
= set_state_slist(&cur_slist
, owner
, name
, sym
, state
);
126 if (cond_true_stack
) {
127 set_state_stack(&cond_true_stack
, owner
, name
, sym
, state
);
128 set_state_stack(&cond_false_stack
, owner
, name
, sym
, state
);
133 struct sm_state
*set_state_expr(int owner
, struct expression
*expr
, struct smatch_state
*state
)
137 struct sm_state
*ret
= NULL
;
139 expr
= strip_expr(expr
);
140 name
= get_variable_from_expr(expr
, &sym
);
143 ret
= set_state(owner
, name
, sym
, state
);
149 void __push_fake_cur_slist()
151 push_slist(&fake_cur_slist_stack
, NULL
);
152 __save_pre_cond_states();
155 struct state_list
*__pop_fake_cur_slist()
157 __use_pre_cond_states();
158 return pop_slist(&fake_cur_slist_stack
);
161 void __merge_slist_into_cur(struct state_list
*slist
)
164 struct sm_state
*orig
;
165 struct sm_state
*merged
;
167 FOR_EACH_PTR(slist
, sm
) {
168 orig
= get_sm_state(sm
->owner
, sm
->name
, sm
->sym
);
170 merged
= merge_sm_states(orig
, sm
);
174 } END_FOR_EACH_PTR(sm
);
177 void __set_sm(struct sm_state
*sm
)
180 struct smatch_state
*s
;
182 s
= get_state(sm
->owner
, sm
->name
, sm
->sym
);
184 printf("%d new state. name='%s' [%s] %s\n",
185 get_lineno(), sm
->name
, check_name(sm
->owner
),
186 show_state(sm
->state
));
188 printf("%d state change name='%s' [%s] %s => %s\n",
189 get_lineno(), sm
->name
, check_name(sm
->owner
), show_state(s
),
190 show_state(sm
->state
));
196 overwrite_sm_state(&cur_slist
, sm
);
198 if (cond_true_stack
) {
199 overwrite_sm_state_stack(&cond_true_stack
, sm
);
200 overwrite_sm_state_stack(&cond_false_stack
, sm
);
204 struct smatch_state
*get_state(int owner
, const char *name
, struct symbol
*sym
)
206 return get_state_slist(cur_slist
, owner
, name
, sym
);
209 struct smatch_state
*get_state_expr(int owner
, struct expression
*expr
)
213 struct smatch_state
*ret
= NULL
;
215 expr
= strip_expr(expr
);
216 name
= get_variable_from_expr(expr
, &sym
);
219 ret
= get_state(owner
, name
, sym
);
225 struct state_list
*get_possible_states(int owner
, const char *name
, struct symbol
*sym
)
227 struct sm_state
*sms
;
229 sms
= get_sm_state_slist(cur_slist
, owner
, name
, sym
);
231 return sms
->possible
;
235 struct state_list
*get_possible_states_expr(int owner
, struct expression
*expr
)
239 struct state_list
*ret
= NULL
;
241 expr
= strip_expr(expr
);
242 name
= get_variable_from_expr(expr
, &sym
);
245 ret
= get_possible_states(owner
, name
, sym
);
251 struct sm_state
*get_sm_state(int owner
, const char *name
, struct symbol
*sym
)
253 return get_sm_state_slist(cur_slist
, owner
, name
, sym
);
256 struct sm_state
*get_sm_state_expr(int owner
, struct expression
*expr
)
260 struct sm_state
*ret
= NULL
;
262 expr
= strip_expr(expr
);
263 name
= get_variable_from_expr(expr
, &sym
);
266 ret
= get_sm_state(owner
, name
, sym
);
272 void delete_state(int owner
, const char *name
, struct symbol
*sym
)
274 delete_state_slist(&cur_slist
, owner
, name
, sym
);
275 if (cond_true_stack
) {
276 delete_state_stack(&pre_cond_stack
, owner
, name
, sym
);
277 delete_state_stack(&cond_true_stack
, owner
, name
, sym
);
278 delete_state_stack(&cond_false_stack
, owner
, name
, sym
);
282 void delete_state_expr(int owner
, struct expression
*expr
)
287 expr
= strip_expr(expr
);
288 name
= get_variable_from_expr(expr
, &sym
);
291 delete_state(owner
, name
, sym
);
296 struct state_list
*get_all_states(int owner
)
298 struct state_list
*slist
= NULL
;
299 struct sm_state
*tmp
;
301 FOR_EACH_PTR(cur_slist
, tmp
) {
302 if (tmp
->owner
== owner
)
303 add_ptr_list(&slist
, tmp
);
304 } END_FOR_EACH_PTR(tmp
);
309 int is_reachable(void)
316 struct state_list
*__get_cur_slist(void)
321 void set_true_false_states(int owner
, const char *name
, struct symbol
*sym
,
322 struct smatch_state
*true_state
,
323 struct smatch_state
*false_state
)
326 struct smatch_state
*tmp
;
328 tmp
= get_state(owner
, name
, sym
);
329 sm_debug("%d set_true_false '%s'. Was %s. Now T:%s F:%s\n",
330 get_lineno(), name
, show_state(tmp
),
331 show_state(true_state
), show_state(false_state
));
337 if (!cond_false_stack
|| !cond_true_stack
) {
338 printf("Error: missing true/false stacks\n");
342 __use_default_modification_hook(owner
, name
);
345 set_state_slist(&cur_slist
, owner
, name
, sym
, true_state
);
346 set_state_stack(&cond_true_stack
, owner
, name
, sym
, true_state
);
349 set_state_stack(&cond_false_stack
, owner
, name
, sym
, false_state
);
352 void set_true_false_states_expr(int owner
, struct expression
*expr
,
353 struct smatch_state
*true_state
,
354 struct smatch_state
*false_state
)
359 expr
= strip_expr(expr
);
360 name
= get_variable_from_expr(expr
, &sym
);
363 set_true_false_states(owner
, name
, sym
, true_state
, false_state
);
368 void __set_true_false_sm(struct sm_state
*true_sm
, struct sm_state
*false_sm
)
373 if (!cond_false_stack
|| !cond_true_stack
) {
374 printf("Error: missing true/false stacks\n");
379 overwrite_sm_state(&cur_slist
, true_sm
);
380 overwrite_sm_state_stack(&cond_true_stack
, true_sm
);
383 overwrite_sm_state_stack(&cond_false_stack
, false_sm
);
386 void nullify_path(void)
388 free_slist(&cur_slist
);
391 void __match_nullify_path_hook(const char *fn
, struct expression
*expr
,
398 * At the start of every function we mark the path
399 * as unnull. That way there is always at least one state
400 * in the cur_slist until nullify_path is called. This
401 * is used in merge_slist() for the first null check.
403 void __unnullify_path(void)
405 set_state(-1, "unnull_path", NULL
, &true_state
);
408 int __path_is_null(void)
415 static void check_stack_free(struct state_list_stack
**stack
)
418 sm_msg("smatch internal error: stack not empty");
419 free_stack_and_slists(stack
);
423 void clear_all_states(void)
425 struct named_slist
*named_slist
;
428 check_stack_free(&true_stack
);
429 check_stack_free(&false_stack
);
430 check_stack_free(&pre_cond_stack
);
431 check_stack_free(&cond_true_stack
);
432 check_stack_free(&cond_false_stack
);
433 check_stack_free(&break_stack
);
434 check_stack_free(&switch_stack
);
435 check_stack_free(&continue_stack
);
436 free_stack_and_slists(&implied_pools
);
438 FOR_EACH_PTR(goto_stack
, named_slist
) {
439 free_slist(&named_slist
->slist
);
440 } END_FOR_EACH_PTR(named_slist
);
441 __free_ptr_list((struct ptr_list
**)&goto_stack
);
442 free_every_single_sm_state();
445 void __push_cond_stacks(void)
447 push_slist(&cond_true_stack
, NULL
);
448 push_slist(&cond_false_stack
, NULL
);
451 struct state_list
*__copy_cond_true_states(void)
453 struct state_list
*ret
;
455 ret
= pop_slist(&cond_true_stack
);
456 push_slist(&cond_true_stack
, clone_slist(ret
));
460 struct state_list
*__copy_cond_false_states(void)
462 struct state_list
*ret
;
464 ret
= pop_slist(&cond_false_stack
);
465 push_slist(&cond_false_stack
, clone_slist(ret
));
469 struct state_list
*__pop_cond_true_stack(void)
471 return pop_slist(&cond_true_stack
);
474 struct state_list
*__pop_cond_false_stack(void)
476 return pop_slist(&cond_false_stack
);
480 * This combines the pre cond states with either the true or false states.
482 * a = kmalloc() ; if (a !! foo(a)
483 * In the pre state a is possibly null. In the true state it is non null.
484 * In the false state it is null. Combine the pre and the false to get
485 * that when we call 'foo', 'a' is null.
487 static void __use_cond_stack(struct state_list_stack
**stack
)
489 struct state_list
*slist
;
491 free_slist(&cur_slist
);
493 cur_slist
= pop_slist(&pre_cond_stack
);
494 push_slist(&pre_cond_stack
, clone_slist(cur_slist
));
496 slist
= pop_slist(stack
);
497 overwrite_slist(slist
, &cur_slist
);
498 push_slist(stack
, slist
);
501 void __use_pre_cond_states(void)
503 free_slist(&cur_slist
);
504 cur_slist
= pop_slist(&pre_cond_stack
);
507 void __use_cond_true_states(void)
509 __use_cond_stack(&cond_true_stack
);
512 void __use_cond_false_states(void)
514 __use_cond_stack(&cond_false_stack
);
517 void __negate_cond_stacks(void)
519 struct state_list
*old_false
, *old_true
;
521 __use_cond_stack(&cond_false_stack
);
522 old_false
= pop_slist(&cond_false_stack
);
523 old_true
= pop_slist(&cond_true_stack
);
524 push_slist(&cond_false_stack
, old_true
);
525 push_slist(&cond_true_stack
, old_false
);
528 void __and_cond_states(void)
530 and_slist_stack(&cond_true_stack
);
531 or_slist_stack(&pre_cond_stack
, cur_slist
, &cond_false_stack
);
534 void __or_cond_states(void)
536 or_slist_stack(&pre_cond_stack
, cur_slist
, &cond_true_stack
);
537 and_slist_stack(&cond_false_stack
);
540 void __save_pre_cond_states(void)
542 push_slist(&pre_cond_stack
, clone_slist(cur_slist
));
545 void __discard_pre_cond_states(void)
547 struct state_list
*tmp
;
549 tmp
= pop_slist(&pre_cond_stack
);
553 void __use_cond_states(void)
555 struct state_list
*pre
, *pre_clone
, *true_states
, *false_states
;
557 pre
= pop_slist(&pre_cond_stack
);
558 pre_clone
= clone_slist(pre
);
560 true_states
= pop_slist(&cond_true_stack
);
561 overwrite_slist(true_states
, &pre
);
562 /* we use the true states right away */
563 free_slist(&cur_slist
);
566 false_states
= pop_slist(&cond_false_stack
);
567 overwrite_slist(false_states
, &pre_clone
);
568 push_slist(&false_stack
, pre_clone
);
571 void __push_true_states(void)
573 push_slist(&true_stack
, clone_slist(cur_slist
));
576 void __use_false_states(void)
578 free_slist(&cur_slist
);
579 cur_slist
= pop_slist(&false_stack
);
582 void __discard_false_states(void)
584 struct state_list
*slist
;
586 slist
= pop_slist(&false_stack
);
590 void __merge_false_states(void)
592 struct state_list
*slist
;
594 slist
= pop_slist(&false_stack
);
595 merge_slist(&cur_slist
, slist
);
599 void __merge_true_states(void)
601 struct state_list
*slist
;
603 slist
= pop_slist(&true_stack
);
604 merge_slist(&cur_slist
, slist
);
608 void __push_continues(void)
610 push_slist(&continue_stack
, NULL
);
613 void __discard_continues(void)
615 struct state_list
*slist
;
617 slist
= pop_slist(&continue_stack
);
621 void __process_continues(void)
623 struct state_list
*slist
;
625 slist
= pop_slist(&continue_stack
);
627 slist
= clone_slist(cur_slist
);
629 merge_slist(&slist
, cur_slist
);
631 push_slist(&continue_stack
, slist
);
634 static int top_slist_empty(struct state_list_stack
**stack
)
636 struct state_list
*tmp
;
639 tmp
= pop_slist(stack
);
642 push_slist(stack
, tmp
);
646 /* a silly loop does this: while(i--) { return; } */
647 void __warn_on_silly_pre_loops(void)
649 if (!__path_is_null())
651 if (!top_slist_empty(&continue_stack
))
653 if (!top_slist_empty(&break_stack
))
655 /* if the path was nullified before the loop, then we already
656 printed an error earlier */
657 if (top_slist_empty(&false_stack
))
659 sm_msg("info: loop could be replaced with if statement.");
662 void __merge_continues(void)
664 struct state_list
*slist
;
666 slist
= pop_slist(&continue_stack
);
667 merge_slist(&cur_slist
, slist
);
671 void __push_breaks(void)
673 push_slist(&break_stack
, NULL
);
676 void __process_breaks(void)
678 struct state_list
*slist
;
680 slist
= pop_slist(&break_stack
);
682 slist
= clone_slist(cur_slist
);
684 merge_slist(&slist
, cur_slist
);
686 push_slist(&break_stack
, slist
);
689 void __merge_breaks(void)
691 struct state_list
*slist
;
693 slist
= pop_slist(&break_stack
);
694 merge_slist(&cur_slist
, slist
);
698 void __use_breaks(void)
700 free_slist(&cur_slist
);
701 cur_slist
= pop_slist(&break_stack
);
704 void __save_switch_states(struct expression
*switch_expr
)
706 push_range_list(&remaining_cases
, __get_implied_values(switch_expr
));
707 push_slist(&switch_stack
, clone_slist(cur_slist
));
710 void __merge_switches(struct expression
*switch_expr
, struct expression
*case_expr
)
712 struct state_list
*slist
;
713 struct state_list
*implied_slist
;
715 slist
= pop_slist(&switch_stack
);
716 implied_slist
= __implied_case_slist(switch_expr
, case_expr
, &remaining_cases
, &slist
);
717 merge_slist(&cur_slist
, implied_slist
);
718 free_slist(&implied_slist
);
719 push_slist(&switch_stack
, slist
);
722 void __discard_switches(void)
724 struct state_list
*slist
;
726 pop_range_list(&remaining_cases
);
727 slist
= pop_slist(&switch_stack
);
731 void __push_default(void)
733 push_slist(&default_stack
, NULL
);
736 void __set_default(void)
738 set_state_stack(&default_stack
, 0, "has_default", NULL
, &true_state
);
741 int __pop_default(void)
743 struct state_list
*slist
;
745 slist
= pop_slist(&default_stack
);
753 static struct named_slist
*alloc_named_slist(const char *name
, struct state_list
*slist
)
755 struct named_slist
*named_slist
= __alloc_named_slist(0);
757 named_slist
->name
= (char *)name
;
758 named_slist
->slist
= slist
;
762 void __save_gotos(const char *name
)
764 struct state_list
**slist
;
765 struct state_list
*clone
;
767 slist
= get_slist_from_named_stack(goto_stack
, name
);
769 clone
= clone_slist(cur_slist
);
770 merge_slist(slist
, clone
);
774 struct named_slist
*named_slist
;
776 clone
= clone_slist(cur_slist
);
777 named_slist
= alloc_named_slist(name
, clone
);
778 add_ptr_list(&goto_stack
, named_slist
);
782 void __merge_gotos(const char *name
)
784 struct state_list
**slist
;
786 slist
= get_slist_from_named_stack(goto_stack
, name
);
788 merge_slist(&cur_slist
, *slist
);