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 void split_conditions(struct expression
*expr
)
316 char *cond
= get_variable_from_expr_complex(expr
, NULL
);
318 sm_debug("%d in split_conditions (%s)\n", get_lineno(), cond
);
322 expr
= strip_expr(expr
);
326 switch (expr
->type
) {
328 __pass_to_client(expr
, LOGIC_HOOK
);
329 handle_logical(expr
);
332 if (handle_zero_comparisons(expr
))
336 if (ignore_builtin_expect(expr
))
340 if (handle_preop(expr
))
343 case EXPR_CONDITIONAL
:
349 /* fixme: this should be in smatch_flow.c
350 but because of the funny stuff we do with conditions
351 it's awkward to put it there. We would need to
352 call CONDITION_HOOK in smatch_flow as well.
354 push_expression(&big_expression_stack
, expr
);
355 if (expr
->type
== EXPR_COMPARE
) {
356 if (expr
->left
->type
!= EXPR_POSTOP
)
357 __split_expr(expr
->left
);
358 if (expr
->right
->type
!= EXPR_POSTOP
)
359 __split_expr(expr
->right
);
360 } else if (expr
->type
!= EXPR_POSTOP
) {
363 __pass_to_client(expr
, CONDITION_HOOK
);
364 if (expr
->type
== EXPR_COMPARE
) {
365 if (expr
->left
->type
== EXPR_POSTOP
)
366 __split_expr(expr
->left
);
367 if (expr
->right
->type
== EXPR_POSTOP
)
368 __split_expr(expr
->right
);
369 } else if (expr
->type
== EXPR_POSTOP
) {
372 pop_expression(&big_expression_stack
);
375 static int inside_condition
;
376 void __split_whole_condition(struct expression
*expr
)
378 sm_debug("%d in __split_whole_condition\n", get_lineno());
380 __save_pre_cond_states();
381 __push_cond_stacks();
382 /* it's a hack, but it's sometimes handy to have this stuff
383 on the big_expression_stack. */
384 push_expression(&big_expression_stack
, expr
);
386 split_conditions(expr
);
388 __pass_to_client(expr
, WHOLE_CONDITION_HOOK
);
389 pop_expression(&big_expression_stack
);
391 sm_debug("%d done __split_whole_condition\n", get_lineno());
394 void __handle_logic(struct expression
*expr
)
396 sm_debug("%d in __handle_logic\n", get_lineno());
398 __save_pre_cond_states();
399 __push_cond_stacks();
400 /* it's a hack, but it's sometimes handy to have this stuff
401 on the big_expression_stack. */
402 push_expression(&big_expression_stack
, expr
);
404 split_conditions(expr
);
406 __pass_to_client(expr
, WHOLE_CONDITION_HOOK
);
407 pop_expression(&big_expression_stack
);
408 __merge_false_states();
410 sm_debug("%d done __handle_logic\n", get_lineno());
413 int __is_condition_assign(struct expression
*expr
)
415 struct expression
*right
;
417 right
= strip_expr(expr
->right
);
418 switch (right
->type
) {
423 if (right
->op
== '!')
432 int __handle_condition_assigns(struct expression
*expr
)
434 struct expression
*right
;
436 right
= strip_expr(expr
->right
);
437 if (!__is_condition_assign(expr
))
440 sm_debug("%d in __handle_condition_assigns\n", get_lineno());
442 __save_pre_cond_states();
443 __push_cond_stacks();
444 /* it's a hack, but it's sometimes handy to have this stuff
445 on the big_expression_stack. */
446 push_expression(&big_expression_stack
, right
);
447 split_conditions(right
);
448 set_true_false_states_expr(SMATCH_EXTRA
, expr
->left
, alloc_extra_state(1), alloc_extra_state(0));
450 __pass_to_client(right
, WHOLE_CONDITION_HOOK
);
451 pop_expression(&big_expression_stack
);
453 sm_debug("%d done __handle_condition_assigns\n", get_lineno());
455 __push_true_states();
456 __use_false_states();
457 __merge_true_states();
458 __pass_to_client(expr
, ASSIGNMENT_HOOK
);
462 static int is_select_assign(struct expression
*expr
)
464 struct expression
*right
;
468 right
= strip_expr(expr
->right
);
469 if (right
->type
== EXPR_CONDITIONAL
)
471 if (right
->type
== EXPR_SELECT
)
476 static void set_fake_assign(struct expression
*new,
477 struct expression
*left
, struct expression
*right
)
480 new->pos
= left
->pos
;
482 new->type
= EXPR_ASSIGNMENT
;
487 int __handle_select_assigns(struct expression
*expr
)
489 struct expression
*right
;
490 struct state_list
*final_states
= NULL
;
495 if (!is_select_assign(expr
))
497 sm_debug("%d in __handle_ternary_assigns\n", get_lineno());
498 right
= strip_expr(expr
->right
);
500 is_true
= implied_condition_true(right
->conditional
);
501 is_false
= implied_condition_false(right
->conditional
);
503 /* hah hah. the ultra fake out */
504 __save_pre_cond_states();
505 __split_whole_condition(right
->conditional
);
508 struct expression fake_expr
;
510 if (right
->cond_true
)
511 set_fake_assign(&fake_expr
, expr
->left
, right
->cond_true
);
513 set_fake_assign(&fake_expr
, expr
->left
, right
->conditional
);
514 __split_expr(&fake_expr
);
515 final_states
= clone_slist(__get_cur_slist());
518 __use_false_states();
520 struct expression fake_expr
;
522 set_fake_assign(&fake_expr
, expr
->left
, right
->cond_false
);
523 __split_expr(&fake_expr
);
524 merge_slist(&final_states
, __get_cur_slist());
527 __use_pre_cond_states();
529 FOR_EACH_PTR(final_states
, sm
) {
531 } END_FOR_EACH_PTR(sm
);
533 free_slist(&final_states
);
535 sm_debug("%d done __handle_ternary_assigns\n", get_lineno());
540 static struct statement
*split_then_return_last(struct statement
*stmt
)
542 struct statement
*tmp
;
543 struct statement
*last_stmt
;
545 last_stmt
= last_ptr_list((struct ptr_list
*)stmt
->stmts
);
549 __push_scope_hooks();
550 FOR_EACH_PTR(stmt
->stmts
, tmp
) {
551 if (tmp
== last_stmt
)
554 } END_FOR_EACH_PTR(tmp
);
558 int __handle_expr_statement_assigns(struct expression
*expr
)
560 struct expression
*right
;
561 struct statement
*stmt
;
564 if (right
->type
== EXPR_PREOP
&& right
->op
== '(')
566 if (right
->type
!= EXPR_STATEMENT
)
570 stmt
= right
->statement
;
571 if (stmt
->type
== STMT_COMPOUND
) {
572 struct statement
*last_stmt
;
573 struct expression fake_assign
;
574 struct expression fake_expr_stmt
;
576 last_stmt
= split_then_return_last(stmt
);
582 fake_expr_stmt
.pos
= last_stmt
->pos
;
583 fake_expr_stmt
.type
= EXPR_STATEMENT
;
584 fake_expr_stmt
.statement
= last_stmt
;
586 fake_assign
.pos
= last_stmt
->pos
;
587 fake_assign
.op
= (int)'=';
588 fake_assign
.type
= EXPR_ASSIGNMENT
;
589 fake_assign
.left
= expr
->left
;
590 fake_assign
.right
= &fake_expr_stmt
;
592 __split_expr(&fake_assign
);
594 __call_scope_hooks();
595 } else if (stmt
->type
== STMT_EXPRESSION
) {
596 struct expression fake_assign
;
598 fake_assign
.pos
= stmt
->pos
;
599 fake_assign
.op
= (int)'=';
600 fake_assign
.type
= EXPR_ASSIGNMENT
;
601 fake_assign
.left
= expr
->left
;
602 fake_assign
.right
= stmt
->expression
;
604 __split_expr(&fake_assign
);
612 int in_condition(void)
614 return inside_condition
;