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 if (fake_cur_slist_stack
)
120 set_state_stack(&fake_cur_slist_stack
, owner
, name
, sym
, state
);
122 ret
= set_state_slist(&cur_slist
, owner
, name
, sym
, state
);
124 if (cond_true_stack
) {
125 set_state_stack(&cond_true_stack
, owner
, name
, sym
, state
);
126 set_state_stack(&cond_false_stack
, owner
, name
, sym
, state
);
131 struct sm_state
*set_state_expr(int owner
, struct expression
*expr
, struct smatch_state
*state
)
135 struct sm_state
*ret
= NULL
;
137 expr
= strip_expr(expr
);
138 name
= get_variable_from_expr(expr
, &sym
);
141 ret
= set_state(owner
, name
, sym
, state
);
147 void __push_fake_cur_slist()
149 push_slist(&fake_cur_slist_stack
, NULL
);
150 __save_pre_cond_states();
153 struct state_list
*__pop_fake_cur_slist()
155 __use_pre_cond_states();
156 return pop_slist(&fake_cur_slist_stack
);
159 void __merge_slist_into_cur(struct state_list
*slist
)
162 struct sm_state
*orig
;
163 struct sm_state
*merged
;
165 FOR_EACH_PTR(slist
, sm
) {
166 orig
= get_sm_state(sm
->owner
, sm
->name
, sm
->sym
);
168 merged
= merge_sm_states(orig
, sm
);
172 } END_FOR_EACH_PTR(sm
);
175 void __set_sm(struct sm_state
*sm
)
178 struct smatch_state
*s
;
180 s
= get_state(sm
->owner
, sm
->name
, sm
->sym
);
182 printf("%d new state. name='%s' [%s] %s\n",
183 get_lineno(), sm
->name
, check_name(sm
->owner
),
184 show_state(sm
->state
));
186 printf("%d state change name='%s' [%s] %s => %s\n",
187 get_lineno(), sm
->name
, check_name(sm
->owner
), show_state(s
),
188 show_state(sm
->state
));
194 overwrite_sm_state(&cur_slist
, sm
);
196 if (cond_true_stack
) {
197 overwrite_sm_state_stack(&cond_true_stack
, sm
);
198 overwrite_sm_state_stack(&cond_false_stack
, sm
);
202 struct smatch_state
*get_state(int owner
, const char *name
, struct symbol
*sym
)
204 return get_state_slist(cur_slist
, owner
, name
, sym
);
207 struct smatch_state
*get_state_expr(int owner
, struct expression
*expr
)
211 struct smatch_state
*ret
= NULL
;
213 expr
= strip_expr(expr
);
214 name
= get_variable_from_expr(expr
, &sym
);
217 ret
= get_state(owner
, name
, sym
);
223 struct state_list
*get_possible_states(int owner
, const char *name
, struct symbol
*sym
)
225 struct sm_state
*sms
;
227 sms
= get_sm_state_slist(cur_slist
, owner
, name
, sym
);
229 return sms
->possible
;
233 struct state_list
*get_possible_states_expr(int owner
, struct expression
*expr
)
237 struct state_list
*ret
= NULL
;
239 expr
= strip_expr(expr
);
240 name
= get_variable_from_expr(expr
, &sym
);
243 ret
= get_possible_states(owner
, name
, sym
);
249 struct sm_state
*get_sm_state(int owner
, const char *name
, struct symbol
*sym
)
251 return get_sm_state_slist(cur_slist
, owner
, name
, sym
);
254 struct sm_state
*get_sm_state_expr(int owner
, struct expression
*expr
)
258 struct sm_state
*ret
= NULL
;
260 expr
= strip_expr(expr
);
261 name
= get_variable_from_expr(expr
, &sym
);
264 ret
= get_sm_state(owner
, name
, sym
);
270 void delete_state(int owner
, const char *name
, struct symbol
*sym
)
272 delete_state_slist(&cur_slist
, owner
, name
, sym
);
273 if (cond_true_stack
) {
274 delete_state_stack(&pre_cond_stack
, owner
, name
, sym
);
275 delete_state_stack(&cond_true_stack
, owner
, name
, sym
);
276 delete_state_stack(&cond_false_stack
, owner
, name
, sym
);
280 void delete_state_expr(int owner
, struct expression
*expr
)
285 expr
= strip_expr(expr
);
286 name
= get_variable_from_expr(expr
, &sym
);
289 delete_state(owner
, name
, sym
);
294 struct state_list
*get_all_states_slist(int owner
, struct state_list
*source
)
296 struct state_list
*slist
= NULL
;
297 struct sm_state
*tmp
;
299 FOR_EACH_PTR(source
, tmp
) {
300 if (tmp
->owner
== owner
)
301 add_ptr_list(&slist
, tmp
);
302 } END_FOR_EACH_PTR(tmp
);
307 struct state_list
*get_all_states(int owner
)
309 struct state_list
*slist
= NULL
;
310 struct sm_state
*tmp
;
312 FOR_EACH_PTR(cur_slist
, tmp
) {
313 if (tmp
->owner
== owner
)
314 add_ptr_list(&slist
, tmp
);
315 } END_FOR_EACH_PTR(tmp
);
320 int is_reachable(void)
327 struct state_list
*__get_cur_slist(void)
332 void set_true_false_states(int owner
, const char *name
, struct symbol
*sym
,
333 struct smatch_state
*true_state
,
334 struct smatch_state
*false_state
)
337 struct smatch_state
*tmp
;
339 tmp
= get_state(owner
, name
, sym
);
340 sm_debug("%d set_true_false '%s'. Was %s. Now T:%s F:%s\n",
341 get_lineno(), name
, show_state(tmp
),
342 show_state(true_state
), show_state(false_state
));
348 if (!cond_false_stack
|| !cond_true_stack
) {
349 printf("Error: missing true/false stacks\n");
354 set_state_slist(&cur_slist
, owner
, name
, sym
, true_state
);
355 set_state_stack(&cond_true_stack
, owner
, name
, sym
, true_state
);
358 set_state_stack(&cond_false_stack
, owner
, name
, sym
, false_state
);
361 void set_true_false_states_expr(int owner
, struct expression
*expr
,
362 struct smatch_state
*true_state
,
363 struct smatch_state
*false_state
)
368 expr
= strip_expr(expr
);
369 name
= get_variable_from_expr(expr
, &sym
);
372 set_true_false_states(owner
, name
, sym
, true_state
, false_state
);
377 void __set_true_false_sm(struct sm_state
*true_sm
, struct sm_state
*false_sm
)
382 if (!cond_false_stack
|| !cond_true_stack
) {
383 printf("Error: missing true/false stacks\n");
388 overwrite_sm_state(&cur_slist
, true_sm
);
389 overwrite_sm_state_stack(&cond_true_stack
, true_sm
);
392 overwrite_sm_state_stack(&cond_false_stack
, false_sm
);
395 void nullify_path(void)
397 free_slist(&cur_slist
);
400 void __match_nullify_path_hook(const char *fn
, struct expression
*expr
,
407 * At the start of every function we mark the path
408 * as unnull. That way there is always at least one state
409 * in the cur_slist until nullify_path is called. This
410 * is used in merge_slist() for the first null check.
412 void __unnullify_path(void)
414 set_state(-1, "unnull_path", NULL
, &true_state
);
417 int __path_is_null(void)
424 static void check_stack_free(struct state_list_stack
**stack
)
427 sm_msg("smatch internal error: stack not empty");
428 free_stack_and_slists(stack
);
432 void clear_all_states(void)
434 struct named_slist
*named_slist
;
437 check_stack_free(&true_stack
);
438 check_stack_free(&false_stack
);
439 check_stack_free(&pre_cond_stack
);
440 check_stack_free(&cond_true_stack
);
441 check_stack_free(&cond_false_stack
);
442 check_stack_free(&break_stack
);
443 check_stack_free(&switch_stack
);
444 check_stack_free(&continue_stack
);
445 free_stack_and_slists(&implied_pools
);
447 FOR_EACH_PTR(goto_stack
, named_slist
) {
448 free_slist(&named_slist
->slist
);
449 } END_FOR_EACH_PTR(named_slist
);
450 __free_ptr_list((struct ptr_list
**)&goto_stack
);
451 free_every_single_sm_state();
454 void __push_cond_stacks(void)
456 push_slist(&cond_true_stack
, NULL
);
457 push_slist(&cond_false_stack
, NULL
);
460 struct state_list
*__copy_cond_true_states(void)
462 struct state_list
*ret
;
464 ret
= pop_slist(&cond_true_stack
);
465 push_slist(&cond_true_stack
, clone_slist(ret
));
469 struct state_list
*__copy_cond_false_states(void)
471 struct state_list
*ret
;
473 ret
= pop_slist(&cond_false_stack
);
474 push_slist(&cond_false_stack
, clone_slist(ret
));
478 struct state_list
*__pop_cond_true_stack(void)
480 return pop_slist(&cond_true_stack
);
483 struct state_list
*__pop_cond_false_stack(void)
485 return pop_slist(&cond_false_stack
);
489 * This combines the pre cond states with either the true or false states.
491 * a = kmalloc() ; if (a !! foo(a)
492 * In the pre state a is possibly null. In the true state it is non null.
493 * In the false state it is null. Combine the pre and the false to get
494 * that when we call 'foo', 'a' is null.
496 static void __use_cond_stack(struct state_list_stack
**stack
)
498 struct state_list
*slist
;
500 free_slist(&cur_slist
);
502 cur_slist
= pop_slist(&pre_cond_stack
);
503 push_slist(&pre_cond_stack
, clone_slist(cur_slist
));
505 slist
= pop_slist(stack
);
506 overwrite_slist(slist
, &cur_slist
);
507 push_slist(stack
, slist
);
510 void __use_pre_cond_states(void)
512 free_slist(&cur_slist
);
513 cur_slist
= pop_slist(&pre_cond_stack
);
516 void __use_cond_true_states(void)
518 __use_cond_stack(&cond_true_stack
);
521 void __use_cond_false_states(void)
523 __use_cond_stack(&cond_false_stack
);
526 void __negate_cond_stacks(void)
528 struct state_list
*old_false
, *old_true
;
530 __use_cond_stack(&cond_false_stack
);
531 old_false
= pop_slist(&cond_false_stack
);
532 old_true
= pop_slist(&cond_true_stack
);
533 push_slist(&cond_false_stack
, old_true
);
534 push_slist(&cond_true_stack
, old_false
);
537 void __and_cond_states(void)
539 and_slist_stack(&cond_true_stack
);
540 or_slist_stack(&pre_cond_stack
, cur_slist
, &cond_false_stack
);
543 void __or_cond_states(void)
545 or_slist_stack(&pre_cond_stack
, cur_slist
, &cond_true_stack
);
546 and_slist_stack(&cond_false_stack
);
549 void __save_pre_cond_states(void)
551 push_slist(&pre_cond_stack
, clone_slist(cur_slist
));
554 void __discard_pre_cond_states(void)
556 struct state_list
*tmp
;
558 tmp
= pop_slist(&pre_cond_stack
);
562 void __use_cond_states(void)
564 struct state_list
*pre
, *pre_clone
, *true_states
, *false_states
;
566 pre
= pop_slist(&pre_cond_stack
);
567 pre_clone
= clone_slist(pre
);
569 true_states
= pop_slist(&cond_true_stack
);
570 overwrite_slist(true_states
, &pre
);
571 /* we use the true states right away */
572 free_slist(&cur_slist
);
575 false_states
= pop_slist(&cond_false_stack
);
576 overwrite_slist(false_states
, &pre_clone
);
577 push_slist(&false_stack
, pre_clone
);
580 void __push_true_states(void)
582 push_slist(&true_stack
, clone_slist(cur_slist
));
585 void __use_false_states(void)
587 free_slist(&cur_slist
);
588 cur_slist
= pop_slist(&false_stack
);
591 void __discard_false_states(void)
593 struct state_list
*slist
;
595 slist
= pop_slist(&false_stack
);
599 void __merge_false_states(void)
601 struct state_list
*slist
;
603 slist
= pop_slist(&false_stack
);
604 merge_slist(&cur_slist
, slist
);
608 void __merge_true_states(void)
610 struct state_list
*slist
;
612 slist
= pop_slist(&true_stack
);
613 merge_slist(&cur_slist
, slist
);
617 void __push_continues(void)
619 push_slist(&continue_stack
, NULL
);
622 void __discard_continues(void)
624 struct state_list
*slist
;
626 slist
= pop_slist(&continue_stack
);
630 void __process_continues(void)
632 struct state_list
*slist
;
634 slist
= pop_slist(&continue_stack
);
636 slist
= clone_slist(cur_slist
);
638 merge_slist(&slist
, cur_slist
);
640 push_slist(&continue_stack
, slist
);
643 static int top_slist_empty(struct state_list_stack
**stack
)
645 struct state_list
*tmp
;
648 tmp
= pop_slist(stack
);
651 push_slist(stack
, tmp
);
655 /* a silly loop does this: while(i--) { return; } */
656 void __warn_on_silly_pre_loops(void)
658 if (!__path_is_null())
660 if (!top_slist_empty(&continue_stack
))
662 if (!top_slist_empty(&break_stack
))
664 /* if the path was nullified before the loop, then we already
665 printed an error earlier */
666 if (top_slist_empty(&false_stack
))
668 sm_msg("info: loop could be replaced with if statement.");
671 void __merge_continues(void)
673 struct state_list
*slist
;
675 slist
= pop_slist(&continue_stack
);
676 merge_slist(&cur_slist
, slist
);
680 void __push_breaks(void)
682 push_slist(&break_stack
, NULL
);
685 void __process_breaks(void)
687 struct state_list
*slist
;
689 slist
= pop_slist(&break_stack
);
691 slist
= clone_slist(cur_slist
);
693 merge_slist(&slist
, cur_slist
);
695 push_slist(&break_stack
, slist
);
698 int __has_breaks(void)
700 struct state_list
*slist
;
703 slist
= pop_slist(&break_stack
);
705 push_slist(&break_stack
, slist
);
709 void __merge_breaks(void)
711 struct state_list
*slist
;
713 slist
= pop_slist(&break_stack
);
714 merge_slist(&cur_slist
, slist
);
718 void __use_breaks(void)
720 free_slist(&cur_slist
);
721 cur_slist
= pop_slist(&break_stack
);
724 void __save_switch_states(struct expression
*switch_expr
)
726 push_range_list(&remaining_cases
, __get_implied_values(switch_expr
));
727 push_slist(&switch_stack
, clone_slist(cur_slist
));
730 void __merge_switches(struct expression
*switch_expr
, struct expression
*case_expr
)
732 struct state_list
*slist
;
733 struct state_list
*implied_slist
;
735 slist
= pop_slist(&switch_stack
);
736 implied_slist
= __implied_case_slist(switch_expr
, case_expr
, &remaining_cases
, &slist
);
737 merge_slist(&cur_slist
, implied_slist
);
738 free_slist(&implied_slist
);
739 push_slist(&switch_stack
, slist
);
742 void __discard_switches(void)
744 struct state_list
*slist
;
746 pop_range_list(&remaining_cases
);
747 slist
= pop_slist(&switch_stack
);
751 void __push_default(void)
753 push_slist(&default_stack
, NULL
);
756 void __set_default(void)
758 set_state_stack(&default_stack
, 0, "has_default", NULL
, &true_state
);
761 int __pop_default(void)
763 struct state_list
*slist
;
765 slist
= pop_slist(&default_stack
);
773 static struct named_slist
*alloc_named_slist(const char *name
, struct state_list
*slist
)
775 struct named_slist
*named_slist
= __alloc_named_slist(0);
777 named_slist
->name
= (char *)name
;
778 named_slist
->slist
= slist
;
782 void __save_gotos(const char *name
)
784 struct state_list
**slist
;
785 struct state_list
*clone
;
787 slist
= get_slist_from_named_stack(goto_stack
, name
);
789 clone
= clone_slist(cur_slist
);
790 merge_slist(slist
, clone
);
794 struct named_slist
*named_slist
;
796 clone
= clone_slist(cur_slist
);
797 named_slist
= alloc_named_slist(name
, clone
);
798 add_ptr_list(&goto_stack
, named_slist
);
802 void __merge_gotos(const char *name
)
804 struct state_list
**slist
;
806 slist
= get_slist_from_named_stack(goto_stack
, name
);
808 merge_slist(&cur_slist
, *slist
);