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
);
72 static int reset_warnings
= 1;
79 if (reset_warnings
|| option_debug
)
80 sm_msg("info: ignoring unreachable code.");
85 void set_state(int owner
, const char *name
, struct symbol
*sym
,
86 struct smatch_state
*state
)
92 struct smatch_state
*s
;
94 s
= get_state(owner
, name
, sym
);
96 printf("%d new state. name='%s' [%s] %s\n",
97 get_lineno(), name
, check_name(owner
), show_state(state
));
99 printf("%d state change name='%s' [%s] %s => %s\n",
100 get_lineno(), name
, check_name(owner
), show_state(s
),
104 if (owner
!= -1 && unreachable())
108 set_state_slist(&__fake_cur_slist
, owner
, name
, sym
, state
);
112 set_state_slist(&cur_slist
, owner
, name
, sym
, state
);
114 if (cond_true_stack
) {
115 set_state_stack(&cond_true_stack
, owner
, name
, sym
, state
);
116 set_state_stack(&cond_false_stack
, owner
, name
, sym
, state
);
120 void set_state_expr(int owner
, struct expression
*expr
,
121 struct smatch_state
*state
)
126 expr
= strip_expr(expr
);
127 name
= get_variable_from_expr(expr
, &sym
);
130 reset_on_container_modified(owner
, expr
);
131 set_state(owner
, name
, sym
, state
);
137 void __set_state(struct sm_state
*sm
)
140 struct smatch_state
*s
;
142 s
= get_state(sm
->owner
, sm
->name
, sm
->sym
);
144 printf("%d new state. name='%s' [%s] %s\n",
145 get_lineno(), sm
->name
, check_name(sm
->owner
),
146 show_state(sm
->state
));
148 printf("%d state change name='%s' [%s] %s => %s\n",
149 get_lineno(), sm
->name
, check_name(sm
->owner
), show_state(s
),
150 show_state(sm
->state
));
156 overwrite_sm_state(&cur_slist
, sm
);
158 if (cond_true_stack
) {
159 overwrite_sm_state_stack(&cond_true_stack
, sm
);
160 overwrite_sm_state_stack(&cond_false_stack
, sm
);
164 struct smatch_state
*get_state(int owner
, const char *name
, struct symbol
*sym
)
166 return get_state_slist(cur_slist
, owner
, name
, sym
);
169 struct smatch_state
*get_state_expr(int owner
, struct expression
*expr
)
173 struct smatch_state
*ret
= NULL
;
175 expr
= strip_expr(expr
);
176 name
= get_variable_from_expr(expr
, &sym
);
179 ret
= get_state(owner
, name
, sym
);
185 struct state_list
*get_possible_states(int owner
, const char *name
,
188 struct sm_state
*sms
;
190 sms
= get_sm_state_slist(cur_slist
, owner
, name
, sym
);
192 return sms
->possible
;
196 struct state_list
*get_possible_states_expr(int owner
, struct expression
*expr
)
200 struct state_list
*ret
= NULL
;
202 expr
= strip_expr(expr
);
203 name
= get_variable_from_expr(expr
, &sym
);
206 ret
= get_possible_states(owner
, name
, sym
);
212 struct sm_state
*get_sm_state(int owner
, const char *name
, struct symbol
*sym
)
214 return get_sm_state_slist(cur_slist
, owner
, name
, sym
);
217 struct sm_state
*get_sm_state_expr(int owner
, struct expression
*expr
)
221 struct sm_state
*ret
= NULL
;
223 expr
= strip_expr(expr
);
224 name
= get_variable_from_expr(expr
, &sym
);
227 ret
= get_sm_state(owner
, name
, sym
);
233 void delete_state(int owner
, const char *name
, struct symbol
*sym
)
235 delete_state_slist(&cur_slist
, owner
, name
, sym
);
236 if (cond_true_stack
) {
237 delete_state_stack(&pre_cond_stack
, owner
, name
, sym
);
238 delete_state_stack(&cond_true_stack
, owner
, name
, sym
);
239 delete_state_stack(&cond_false_stack
, owner
, name
, sym
);
243 void delete_state_expr(int owner
, struct expression
*expr
)
248 expr
= strip_expr(expr
);
249 name
= get_variable_from_expr(expr
, &sym
);
252 delete_state(owner
, name
, sym
);
257 struct state_list
*get_all_states(int owner
)
259 struct state_list
*slist
= NULL
;
260 struct sm_state
*tmp
;
262 FOR_EACH_PTR(cur_slist
, tmp
) {
263 if (tmp
->owner
== owner
) {
264 add_ptr_list(&slist
, tmp
);
266 } END_FOR_EACH_PTR(tmp
);
271 int is_reachable(void)
278 struct state_list
*__get_cur_slist(void)
283 void set_true_false_states(int owner
, const char *name
, struct symbol
*sym
,
284 struct smatch_state
*true_state
,
285 struct smatch_state
*false_state
)
288 struct smatch_state
*tmp
;
290 tmp
= get_state(owner
, name
, sym
);
291 sm_debug("%d set_true_false '%s'. Was %s. Now T:%s F:%s\n",
292 get_lineno(), name
, show_state(tmp
),
293 show_state(true_state
), show_state(false_state
));
299 if (__fake_conditions
) {
301 set_state_slist(&__fake_cond_true
, owner
, name
, sym
, true_state
);
303 set_state_slist(&__fake_cond_false
, owner
, name
, sym
, false_state
);
307 if (!cond_false_stack
|| !cond_true_stack
) {
308 printf("Error: missing true/false stacks\n");
313 set_state_slist(&cur_slist
, owner
, name
, sym
, true_state
);
314 set_state_stack(&cond_true_stack
, owner
, name
, sym
, true_state
);
317 set_state_stack(&cond_false_stack
, owner
, name
, sym
, false_state
);
320 void set_true_false_states_expr(int owner
, struct expression
*expr
,
321 struct smatch_state
*true_state
,
322 struct smatch_state
*false_state
)
327 expr
= strip_expr(expr
);
328 name
= get_variable_from_expr(expr
, &sym
);
331 reset_on_container_modified(owner
, expr
);
332 set_true_false_states(owner
, name
, sym
, true_state
, false_state
);
337 void __set_true_false_sm(struct sm_state
*true_state
,
338 struct sm_state
*false_state
)
343 if (!cond_false_stack
|| !cond_true_stack
) {
344 printf("Error: missing true/false stacks\n");
349 overwrite_sm_state(&cur_slist
, true_state
);
350 overwrite_sm_state_stack(&cond_true_stack
, true_state
);
353 overwrite_sm_state_stack(&cond_false_stack
, false_state
);
356 void nullify_path(void)
358 free_slist(&cur_slist
);
361 void __match_nullify_path_hook(const char *fn
, struct expression
*expr
,
367 * At the start of every function we mark the path
368 * as unnull. That there is always at least one state
369 * in the cur_slist until nullify_path is called. This
370 * is used in merge_slist() for the first null check.
373 void __unnullify_path(void)
375 set_state(-1, "unnull_path", NULL
, &true_state
);
378 int __path_is_null(void)
385 void clear_all_states(void)
387 struct named_slist
*named_slist
;
390 free_stack_and_slists(&true_stack
);
391 free_stack_and_slists(&false_stack
);
392 free_stack_and_slists(&pre_cond_stack
);
393 free_stack_and_slists(&cond_true_stack
);
394 free_stack_and_slists(&cond_false_stack
);
395 free_stack_and_slists(&break_stack
);
396 free_stack_and_slists(&switch_stack
);
397 free_stack_and_slists(&continue_stack
);
398 free_stack_and_slists(&implied_pools
);
400 FOR_EACH_PTR(goto_stack
, named_slist
) {
401 free_slist(&named_slist
->slist
);
402 } END_FOR_EACH_PTR(named_slist
);
403 __free_ptr_list((struct ptr_list
**)&goto_stack
);
404 free_every_single_sm_state();
408 void __push_cond_stacks(void)
410 push_slist(&cond_true_stack
, NULL
);
411 push_slist(&cond_false_stack
, NULL
);
415 * This combines the pre cond states with either the true or false states.
417 * a = kmalloc() ; if (a !! foo(a)
418 * In the pre state a is possibly null. In the true state it is non null.
419 * In the false state it is null. Combine the pre and the false to get
420 * that when we call 'foo', 'a' is null.
423 static void __use_cond_stack(struct state_list_stack
**stack
)
425 struct state_list
*slist
;
427 free_slist(&cur_slist
);
429 cur_slist
= pop_slist(&pre_cond_stack
);
430 push_slist(&pre_cond_stack
, clone_slist(cur_slist
));
432 slist
= pop_slist(stack
);
433 overwrite_slist(slist
, &cur_slist
);
434 push_slist(stack
, slist
);
437 void __save_false_states_for_later(void)
439 struct state_list
*pre_conditions
;
440 struct state_list
*false_states
;
441 struct state_list
*tmp
;
443 pre_conditions
= pop_slist(&pre_cond_stack
);
444 false_states
= pop_slist(&cond_false_stack
);
445 tmp
= clone_slist(pre_conditions
);
447 overwrite_slist(false_states
, &tmp
);
449 push_slist(&pre_cond_stack
, tmp
);
450 push_slist(&pre_cond_stack
, pre_conditions
);
451 push_slist(&cond_false_stack
, false_states
);
454 void __use_previously_stored_false_states(void)
456 free_slist(&cur_slist
);
457 cur_slist
= pop_slist(&pre_cond_stack
);
460 void __use_cond_true_states(void)
462 __use_cond_stack(&cond_true_stack
);
465 void __use_cond_false_states(void)
467 __use_cond_stack(&cond_false_stack
);
470 void __negate_cond_stacks(void)
472 struct state_list
*old_false
, *old_true
;
474 __use_cond_stack(&cond_false_stack
);
475 old_false
= pop_slist(&cond_false_stack
);
476 old_true
= pop_slist(&cond_true_stack
);
477 push_slist(&cond_false_stack
, old_true
);
478 push_slist(&cond_true_stack
, old_false
);
481 void __and_cond_states(void)
483 and_slist_stack(&cond_true_stack
);
484 or_slist_stack(&pre_cond_stack
, cur_slist
, &cond_false_stack
);
487 void __or_cond_states(void)
489 or_slist_stack(&pre_cond_stack
, cur_slist
, &cond_true_stack
);
490 and_slist_stack(&cond_false_stack
);
493 void __save_pre_cond_states(void)
495 push_slist(&pre_cond_stack
, clone_slist(cur_slist
));
498 void __pop_pre_cond_states(void)
500 struct state_list
*tmp
;
502 tmp
= pop_slist(&pre_cond_stack
);
506 void __use_cond_states(void)
508 struct state_list
*pre
, *pre_clone
, *true_states
, *false_states
;
510 pre
= pop_slist(&pre_cond_stack
);
511 pre_clone
= clone_slist(pre
);
513 true_states
= pop_slist(&cond_true_stack
);
514 overwrite_slist(true_states
, &pre
);
515 /* we use the true states right away */
516 free_slist(&cur_slist
);
520 false_states
= pop_slist(&cond_false_stack
);
521 overwrite_slist(false_states
, &pre_clone
);
522 push_slist(&false_stack
, pre_clone
);
525 void __push_true_states(void)
527 push_slist(&true_stack
, clone_slist(cur_slist
));
530 void __use_false_states(void)
532 free_slist(&cur_slist
);
533 cur_slist
= pop_slist(&false_stack
);
536 void __pop_false_states(void)
538 struct state_list
*slist
;
540 slist
= pop_slist(&false_stack
);
544 void __merge_false_states(void)
546 struct state_list
*slist
;
548 slist
= pop_slist(&false_stack
);
549 merge_slist(&cur_slist
, slist
);
553 void __merge_true_states(void)
555 struct state_list
*slist
;
557 slist
= pop_slist(&true_stack
);
558 merge_slist(&cur_slist
, slist
);
562 void __push_continues(void)
564 push_slist(&continue_stack
, NULL
);
567 void __pop_continues(void)
569 struct state_list
*slist
;
571 slist
= pop_slist(&continue_stack
);
575 void __process_continues(void)
577 struct state_list
*slist
;
579 slist
= pop_slist(&continue_stack
);
581 slist
= clone_slist(cur_slist
);
583 merge_slist(&slist
, cur_slist
);
585 push_slist(&continue_stack
, slist
);
588 static int top_slist_empty(struct state_list_stack
**stack
)
590 struct state_list
*tmp
;
593 tmp
= pop_slist(stack
);
596 push_slist(stack
, tmp
);
600 /* a silly loop does this: while(i--) { return; } */
601 void __warn_on_silly_pre_loops(void)
603 if (!__path_is_null())
605 if (!top_slist_empty(&continue_stack
))
607 if (!top_slist_empty(&break_stack
))
609 /* if the path was nullified before the loop, then we already
610 printed an error earlier */
611 if (top_slist_empty(&false_stack
))
613 sm_msg("info: loop could be replaced with if statement.");
616 void __merge_continues(void)
618 struct state_list
*slist
;
620 slist
= pop_slist(&continue_stack
);
621 merge_slist(&cur_slist
, slist
);
625 void __push_breaks(void)
627 push_slist(&break_stack
, NULL
);
630 void __process_breaks(void)
632 struct state_list
*slist
;
634 slist
= pop_slist(&break_stack
);
636 slist
= clone_slist(cur_slist
);
638 merge_slist(&slist
, cur_slist
);
640 push_slist(&break_stack
, slist
);
643 void __merge_breaks(void)
645 struct state_list
*slist
;
647 slist
= pop_slist(&break_stack
);
648 merge_slist(&cur_slist
, slist
);
652 void __use_breaks(void)
654 free_slist(&cur_slist
);
655 cur_slist
= pop_slist(&break_stack
);
658 void __save_switch_states(struct expression
*switch_expr
)
660 push_range_list(&remaining_cases
, __get_implied_values(switch_expr
));
661 push_slist(&switch_stack
, clone_slist(cur_slist
));
664 void __merge_switches(struct expression
*switch_expr
, struct expression
*case_expr
)
666 struct state_list
*slist
;
667 struct state_list
*implied_slist
;
669 slist
= pop_slist(&switch_stack
);
670 implied_slist
= __implied_case_slist(switch_expr
, case_expr
, &remaining_cases
, &slist
);
671 merge_slist(&cur_slist
, implied_slist
);
672 free_slist(&implied_slist
);
673 push_slist(&switch_stack
, slist
);
676 void __pop_switches(void)
678 struct state_list
*slist
;
680 pop_range_list(&remaining_cases
);
681 slist
= pop_slist(&switch_stack
);
685 void __push_default(void)
687 push_slist(&default_stack
, NULL
);
690 void __set_default(void)
692 set_state_stack(&default_stack
, 0, "has_default", NULL
, &true_state
);
695 int __pop_default(void)
697 struct state_list
*slist
;
699 slist
= pop_slist(&default_stack
);
707 static struct named_slist
*alloc_named_slist(const char *name
,
708 struct state_list
*slist
)
710 struct named_slist
*named_slist
= __alloc_named_slist(0);
712 named_slist
->name
= (char *)name
;
713 named_slist
->slist
= slist
;
717 void __save_gotos(const char *name
)
719 struct state_list
**slist
;
720 struct state_list
*clone
;
722 slist
= get_slist_from_named_stack(goto_stack
, name
);
724 clone
= clone_slist(cur_slist
);
725 merge_slist(slist
, clone
);
729 struct named_slist
*named_slist
;
731 clone
= clone_slist(cur_slist
);
732 named_slist
= alloc_named_slist(name
, clone
);
733 add_ptr_list(&goto_stack
, named_slist
);
737 void __merge_gotos(const char *name
)
739 struct state_list
**slist
;
741 slist
= get_slist_from_named_stack(goto_stack
, name
);
743 merge_slist(&cur_slist
, *slist
);