2 * sparse/smatch_conditions.c
4 * Copyright (C) 2006,2008 Dan Carpenter.
6 * Licensed under the Open Software License version 1.1
11 * The simplest type of condition is
14 * The next simplest kind of conditions is
16 * In that case 'a' is true when we get to 'b' and both are true
19 * Or's are a little more complicated.
21 * We know 'a' is not true when we get to 'b' but it may be true
24 * If we mix and's and or's that's even more complicated.
25 * if (a && b && c || a && d) { d ;
26 * 'a' is true when we evaluate 'b', and 'd'.
27 * 'b' is true when we evaluate 'c' but otherwise we don't.
29 * The other thing that complicates matters is if we negate
32 * Smatch has passes the un-negated version to the client and flip
33 * the true and false values internally. This makes it easier
36 * And negations can be part of a compound.
37 * if (a && !(b || c)) { d;
38 * In that situation we multiply the negative through to simplify
39 * stuff so that we can remove the parens like this:
40 * if (a && !b && !c) { d;
42 * One other thing is that:
44 * that's basically the same as testing for just 'a' and we simplify
45 * comparisons with zero before passing it to the script.
50 #include "smatch_slist.h"
51 #include "smatch_extra.h"
52 #include "smatch_expression_stacks.h"
54 extern int __expr_stmt_count
;
56 static void split_conditions(struct expression
*expr
);
58 static int is_logical_and(struct expression
*expr
)
60 if (expr
->op
== SPECIAL_LOGICAL_AND
)
65 static int handle_zero_comparisons(struct expression
*expr
)
67 struct expression
*tmp
= NULL
;
69 // if left is zero or right is zero
70 if (is_zero(expr
->left
))
72 else if (is_zero(expr
->right
))
77 // "if (foo != 0)" is the same as "if (foo)"
78 if (expr
->op
== SPECIAL_NOTEQUAL
) {
79 split_conditions(tmp
);
83 // "if (foo == 0)" is the same as "if (!foo)"
84 if (expr
->op
== SPECIAL_EQUAL
) {
85 split_conditions(tmp
);
86 __negate_cond_stacks();
94 * This function is for handling calls to likely/unlikely
97 static int ignore_builtin_expect(struct expression
*expr
)
99 if (sym_name_is("__builtin_expect", expr
->fn
)) {
100 split_conditions(first_ptr_list((struct ptr_list
*) expr
->args
));
107 * handle_compound_stmt() is for: foo = ({blah; blah; blah; 1})
110 static void handle_compound_stmt(struct statement
*stmt
)
112 struct expression
*expr
= NULL
;
113 struct statement
*last
;
116 last
= last_ptr_list((struct ptr_list
*)stmt
->stmts
);
117 if (last
->type
!= STMT_EXPRESSION
)
120 expr
= last
->expression
;
122 FOR_EACH_PTR(stmt
->stmts
, s
) {
125 } END_FOR_EACH_PTR(s
);
126 split_conditions(expr
);
130 static int handle_preop(struct expression
*expr
)
132 struct statement
*stmt
;
134 if (expr
->op
== '!') {
135 split_conditions(expr
->unop
);
136 __negate_cond_stacks();
139 stmt
= get_expression_statement(expr
);
141 handle_compound_stmt(stmt
);
147 static void handle_logical(struct expression
*expr
)
150 * If we come to an "and" expr then:
151 * We split the left side.
152 * We keep all the current states.
153 * We split the right side.
154 * We keep all the states from both true sides.
156 * If it's an "or" expr then:
157 * We save the current slist.
158 * We split the left side.
159 * We use the false states for the right side.
160 * We split the right side.
161 * We save all the states that are the same on both sides.
164 split_conditions(expr
->left
);
166 if (!is_logical_and(expr
))
167 __use_cond_false_states();
169 __push_cond_stacks();
171 __save_pre_cond_states();
172 split_conditions(expr
->right
);
173 __discard_pre_cond_states();
175 if (is_logical_and(expr
))
180 __use_cond_true_states();
183 static struct state_list
*combine(struct state_list
*orig
, struct state_list
*fake
,
184 struct state_list
*new)
186 struct state_list
*ret
= NULL
;
188 overwrite_slist(orig
, &ret
);
189 overwrite_slist(fake
, &ret
);
190 overwrite_slist(new, &ret
);
198 * if ((aaa()?bbb():ccc())) { ...
200 * This is almost the same as:
201 * if ((aaa() && bbb()) || (!aaa() && ccc())) { ...
203 * It's a bit complicated because we shouldn't pass aaa()
204 * to the clients more than once.
207 static void handle_select(struct expression
*expr
)
209 struct state_list
*a_T
= NULL
;
210 struct state_list
*a_F
= NULL
;
211 struct state_list
*a_T_b_T
= NULL
;
212 struct state_list
*a_T_b_F
= NULL
;
213 struct state_list
*a_T_b_fake
= NULL
;
214 struct state_list
*a_F_c_T
= NULL
;
215 struct state_list
*a_F_c_F
= NULL
;
216 struct state_list
*a_F_c_fake
= NULL
;
220 * Imagine we have this: if (a ? b : c) { ...
222 * The condition is true if "a" is true and "b" is true or
223 * "a" is false and "c" is true. It's false if "a" is true
224 * and "b" is false or "a" is false and "c" is false.
226 * The variable name "a_T_b_T" stands for "a true b true" etc.
228 * But if we know "b" is true then we can simpilify things.
229 * The condition is true if "a" is true or if "a" is false and
230 * "c" is true. The only way the condition can be false is if
231 * "a" is false and "c" is false.
233 * The remaining thing is the "a_T_b_fake". When we simplify
234 * the equations we have to take into consideration that other
235 * states may have changed that don't play into the true false
236 * equation. Take the following example:
238 * (flags) = __raw_local_irq_save();
239 * _spin_trylock(lock) ? 1 :
240 * ({ raw_local_irq_restore(flags); 0; });
242 * Smatch has to record that the irq flags were restored on the
247 __save_pre_cond_states();
249 split_conditions(expr
->conditional
);
251 a_T
= __copy_cond_true_states();
252 a_F
= __copy_cond_false_states();
254 __push_cond_stacks();
255 __push_fake_cur_slist();
256 split_conditions(expr
->cond_true
);
257 a_T_b_fake
= __pop_fake_cur_slist();
258 a_T_b_T
= combine(a_T
, a_T_b_fake
, __pop_cond_true_stack());
259 a_T_b_F
= combine(a_T
, a_T_b_fake
, __pop_cond_false_stack());
261 __use_cond_false_states();
263 __push_cond_stacks();
264 __push_fake_cur_slist();
265 split_conditions(expr
->cond_false
);
266 a_F_c_fake
= __pop_fake_cur_slist();
267 a_F_c_T
= combine(a_F
, a_F_c_fake
, __pop_cond_true_stack());
268 a_F_c_F
= combine(a_F
, a_F_c_fake
, __pop_cond_false_stack());
270 /* We have to restore the pre condition states so that
271 implied_condition_true() will use the right cur_slist */
272 __use_pre_cond_states();
274 if (implied_condition_true(expr
->cond_true
)) {
275 free_slist(&a_T_b_T
);
276 free_slist(&a_T_b_F
);
277 a_T_b_T
= clone_slist(a_T
);
278 overwrite_slist(a_T_b_fake
, &a_T_b_T
);
280 if (implied_condition_false(expr
->cond_true
)) {
281 free_slist(&a_T_b_T
);
282 free_slist(&a_T_b_F
);
283 a_T_b_F
= clone_slist(a_T
);
284 overwrite_slist(a_T_b_fake
, &a_T_b_F
);
286 if (implied_condition_true(expr
->cond_false
)) {
287 free_slist(&a_F_c_T
);
288 free_slist(&a_F_c_F
);
289 a_F_c_T
= clone_slist(a_F
);
290 overwrite_slist(a_F_c_fake
, &a_F_c_T
);
292 if (implied_condition_false(expr
->cond_false
)) {
293 free_slist(&a_F_c_T
);
294 free_slist(&a_F_c_F
);
295 a_F_c_F
= clone_slist(a_F
);
296 overwrite_slist(a_F_c_fake
, &a_F_c_F
);
299 merge_slist(&a_T_b_T
, a_F_c_T
);
300 merge_slist(&a_T_b_F
, a_F_c_F
);
302 __pop_cond_true_stack();
303 __pop_cond_false_stack();
304 __push_cond_stacks();
305 FOR_EACH_PTR(a_T_b_T
, sm
) {
306 __set_true_false_sm(sm
, NULL
);
307 } END_FOR_EACH_PTR(sm
);
308 FOR_EACH_PTR(a_T_b_F
, sm
) {
309 __set_true_false_sm(NULL
, sm
);
310 } END_FOR_EACH_PTR(sm
);
313 static int make_op_unsigned(int op
)
317 return SPECIAL_UNSIGNED_LT
;
319 return SPECIAL_UNSIGNED_LTE
;
321 return SPECIAL_UNSIGNED_GT
;
323 return SPECIAL_UNSIGNED_GTE
;
328 static void hackup_unsigned_compares(struct expression
*expr
)
330 if (expr
->type
!= EXPR_COMPARE
)
333 if (type_unsigned(get_type(expr
)))
334 expr
->op
= make_op_unsigned(expr
->op
);
337 static void split_conditions(struct expression
*expr
)
340 char *cond
= expr_to_str(expr
);
342 sm_debug("%d in split_conditions (%s)\n", get_lineno(), cond
);
346 expr
= strip_expr(expr
);
350 switch (expr
->type
) {
352 __pass_to_client(expr
, LOGIC_HOOK
);
353 handle_logical(expr
);
356 hackup_unsigned_compares(expr
);
357 if (handle_zero_comparisons(expr
))
361 if (ignore_builtin_expect(expr
))
365 if (handle_preop(expr
))
368 case EXPR_CONDITIONAL
:
374 /* fixme: this should be in smatch_flow.c
375 but because of the funny stuff we do with conditions
376 it's awkward to put it there. We would need to
377 call CONDITION_HOOK in smatch_flow as well.
379 push_expression(&big_expression_stack
, expr
);
380 if (expr
->type
== EXPR_COMPARE
) {
381 if (expr
->left
->type
!= EXPR_POSTOP
)
382 __split_expr(expr
->left
);
383 if (expr
->right
->type
!= EXPR_POSTOP
)
384 __split_expr(expr
->right
);
385 } else if (expr
->type
!= EXPR_POSTOP
) {
388 __pass_to_client(expr
, CONDITION_HOOK
);
389 if (expr
->type
== EXPR_COMPARE
) {
390 if (expr
->left
->type
== EXPR_POSTOP
)
391 __split_expr(expr
->left
);
392 if (expr
->right
->type
== EXPR_POSTOP
)
393 __split_expr(expr
->right
);
394 } else if (expr
->type
== EXPR_POSTOP
) {
397 pop_expression(&big_expression_stack
);
400 static int inside_condition
;
401 void __split_whole_condition(struct expression
*expr
)
403 sm_debug("%d in __split_whole_condition\n", get_lineno());
405 __save_pre_cond_states();
406 __push_cond_stacks();
407 /* it's a hack, but it's sometimes handy to have this stuff
408 on the big_expression_stack. */
409 push_expression(&big_expression_stack
, expr
);
411 split_conditions(expr
);
413 __pass_to_client(expr
, WHOLE_CONDITION_HOOK
);
414 pop_expression(&big_expression_stack
);
416 sm_debug("%d done __split_whole_condition\n", get_lineno());
419 void __handle_logic(struct expression
*expr
)
421 sm_debug("%d in __handle_logic\n", get_lineno());
423 __save_pre_cond_states();
424 __push_cond_stacks();
425 /* it's a hack, but it's sometimes handy to have this stuff
426 on the big_expression_stack. */
427 push_expression(&big_expression_stack
, expr
);
429 split_conditions(expr
);
431 __pass_to_client(expr
, WHOLE_CONDITION_HOOK
);
432 pop_expression(&big_expression_stack
);
433 __merge_false_states();
435 sm_debug("%d done __handle_logic\n", get_lineno());
438 int is_condition(struct expression
*expr
)
441 expr
= strip_expr(expr
);
445 switch (expr
->type
) {
456 int __handle_condition_assigns(struct expression
*expr
)
458 struct expression
*right
;
460 right
= strip_expr(expr
->right
);
461 if (!is_condition(expr
->right
))
464 sm_debug("%d in __handle_condition_assigns\n", get_lineno());
466 __save_pre_cond_states();
467 __push_cond_stacks();
468 /* it's a hack, but it's sometimes handy to have this stuff
469 on the big_expression_stack. */
470 push_expression(&big_expression_stack
, right
);
471 split_conditions(right
);
472 set_true_false_states_expr(SMATCH_EXTRA
, expr
->left
,
473 alloc_estate_sval(sval_type_val(get_type(expr
->left
), 1)),
474 alloc_estate_sval(sval_type_val(get_type(expr
->left
), 0)));
476 __pass_to_client(right
, WHOLE_CONDITION_HOOK
);
477 pop_expression(&big_expression_stack
);
479 sm_debug("%d done __handle_condition_assigns\n", get_lineno());
481 __push_true_states();
482 __use_false_states();
483 __merge_true_states();
484 __pass_to_client(expr
, ASSIGNMENT_HOOK
);
488 static int is_select_assign(struct expression
*expr
)
490 struct expression
*right
;
494 right
= strip_expr(expr
->right
);
495 if (right
->type
== EXPR_CONDITIONAL
)
497 if (right
->type
== EXPR_SELECT
)
502 static void set_fake_assign(struct expression
*new,
503 struct expression
*left
, int op
, struct expression
*right
)
506 new->pos
= left
->pos
;
508 new->type
= EXPR_ASSIGNMENT
;
513 int __handle_select_assigns(struct expression
*expr
)
515 struct expression
*right
;
516 struct state_list
*final_states
= NULL
;
521 if (!is_select_assign(expr
))
523 sm_debug("%d in __handle_ternary_assigns\n", get_lineno());
524 right
= strip_expr(expr
->right
);
526 is_true
= implied_condition_true(right
->conditional
);
527 is_false
= implied_condition_false(right
->conditional
);
529 /* hah hah. the ultra fake out */
530 __save_pre_cond_states();
531 __split_whole_condition(right
->conditional
);
534 struct expression fake_expr
;
536 if (right
->cond_true
)
537 set_fake_assign(&fake_expr
, expr
->left
, expr
->op
, right
->cond_true
);
539 set_fake_assign(&fake_expr
, expr
->left
, expr
->op
, right
->conditional
);
540 __split_expr(&fake_expr
);
541 final_states
= clone_slist(__get_cur_slist());
544 __use_false_states();
546 struct expression fake_expr
;
548 set_fake_assign(&fake_expr
, expr
->left
, expr
->op
, right
->cond_false
);
549 __split_expr(&fake_expr
);
550 merge_slist(&final_states
, __get_cur_slist());
553 __use_pre_cond_states();
555 FOR_EACH_PTR(final_states
, sm
) {
557 } END_FOR_EACH_PTR(sm
);
559 free_slist(&final_states
);
561 sm_debug("%d done __handle_ternary_assigns\n", get_lineno());
566 static struct statement
*split_then_return_last(struct statement
*stmt
)
568 struct statement
*tmp
;
569 struct statement
*last_stmt
;
571 last_stmt
= last_ptr_list((struct ptr_list
*)stmt
->stmts
);
575 __push_scope_hooks();
576 FOR_EACH_PTR(stmt
->stmts
, tmp
) {
577 if (tmp
== last_stmt
)
580 } END_FOR_EACH_PTR(tmp
);
584 int __handle_expr_statement_assigns(struct expression
*expr
)
586 struct expression
*right
;
587 struct statement
*stmt
;
590 if (right
->type
== EXPR_PREOP
&& right
->op
== '(')
592 if (right
->type
!= EXPR_STATEMENT
)
596 stmt
= right
->statement
;
597 if (stmt
->type
== STMT_COMPOUND
) {
598 struct statement
*last_stmt
;
599 struct expression fake_assign
;
600 struct expression fake_expr_stmt
;
602 last_stmt
= split_then_return_last(stmt
);
608 fake_expr_stmt
.pos
= last_stmt
->pos
;
609 fake_expr_stmt
.type
= EXPR_STATEMENT
;
610 fake_expr_stmt
.statement
= last_stmt
;
612 fake_assign
.pos
= last_stmt
->pos
;
613 fake_assign
.op
= expr
->op
;
614 fake_assign
.type
= EXPR_ASSIGNMENT
;
615 fake_assign
.left
= expr
->left
;
616 fake_assign
.right
= &fake_expr_stmt
;
618 __split_expr(&fake_assign
);
620 __call_scope_hooks();
621 } else if (stmt
->type
== STMT_EXPRESSION
) {
622 struct expression fake_assign
;
624 fake_assign
.pos
= stmt
->pos
;
625 fake_assign
.op
= expr
->op
;
626 fake_assign
.type
= EXPR_ASSIGNMENT
;
627 fake_assign
.left
= expr
->left
;
628 fake_assign
.right
= stmt
->expression
;
630 __split_expr(&fake_assign
);
639 int in_condition(void)
641 return inside_condition
;