2 * Copyright (C) 2006,2008 Dan Carpenter.
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version 2
7 * of the License, or (at your option) any later version.
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, see http://www.gnu.org/copyleft/gpl.txt
19 * The simplest type of condition is
22 * The next simplest kind of conditions is
24 * In that case 'a' is true when we get to 'b' and both are true
27 * Or's are a little more complicated.
29 * We know 'a' is not true when we get to 'b' but it may be true
32 * If we mix and's and or's that's even more complicated.
33 * if (a && b && c || a && d) { d ;
34 * 'a' is true when we evaluate 'b', and 'd'.
35 * 'b' is true when we evaluate 'c' but otherwise we don't.
37 * The other thing that complicates matters is if we negate
40 * Smatch has passes the un-negated version to the client and flip
41 * the true and false values internally. This makes it easier
44 * And negations can be part of a compound.
45 * if (a && !(b || c)) { d;
46 * In that situation we multiply the negative through to simplify
47 * stuff so that we can remove the parens like this:
48 * if (a && !b && !c) { d;
50 * One other thing is that:
52 * that's basically the same as testing for just 'a' and we simplify
53 * comparisons with zero before passing it to the script.
58 #include "smatch_slist.h"
59 #include "smatch_extra.h"
60 #include "smatch_expression_stacks.h"
62 extern int __expr_stmt_count
;
64 static void split_conditions(struct expression
*expr
);
66 static int is_logical_and(struct expression
*expr
)
68 if (expr
->op
== SPECIAL_LOGICAL_AND
)
73 static int handle_zero_comparisons(struct expression
*expr
)
75 struct expression
*tmp
= NULL
;
77 // if left is zero or right is zero
78 if (is_zero(expr
->left
))
80 else if (is_zero(expr
->right
))
85 // "if (foo != 0)" is the same as "if (foo)"
86 if (expr
->op
== SPECIAL_NOTEQUAL
) {
87 split_conditions(tmp
);
91 // "if (foo == 0)" is the same as "if (!foo)"
92 if (expr
->op
== SPECIAL_EQUAL
) {
93 split_conditions(tmp
);
94 __negate_cond_stacks();
102 * This function is for handling calls to likely/unlikely
105 static int ignore_builtin_expect(struct expression
*expr
)
107 if (sym_name_is("__builtin_expect", expr
->fn
)) {
108 split_conditions(first_ptr_list((struct ptr_list
*) expr
->args
));
115 * handle_compound_stmt() is for: foo = ({blah; blah; blah; 1})
118 static void handle_compound_stmt(struct statement
*stmt
)
120 struct expression
*expr
= NULL
;
121 struct statement
*last
;
124 last
= last_ptr_list((struct ptr_list
*)stmt
->stmts
);
125 if (last
->type
!= STMT_EXPRESSION
)
128 expr
= last
->expression
;
130 FOR_EACH_PTR(stmt
->stmts
, s
) {
133 } END_FOR_EACH_PTR(s
);
134 split_conditions(expr
);
138 static int handle_preop(struct expression
*expr
)
140 struct statement
*stmt
;
142 if (expr
->op
== '!') {
143 split_conditions(expr
->unop
);
144 __negate_cond_stacks();
147 stmt
= get_expression_statement(expr
);
149 handle_compound_stmt(stmt
);
155 static void handle_logical(struct expression
*expr
)
158 * If we come to an "and" expr then:
159 * We split the left side.
160 * We keep all the current states.
161 * We split the right side.
162 * We keep all the states from both true sides.
164 * If it's an "or" expr then:
165 * We save the current slist.
166 * We split the left side.
167 * We use the false states for the right side.
168 * We split the right side.
169 * We save all the states that are the same on both sides.
172 split_conditions(expr
->left
);
173 __process_post_op_stack();
175 if (!is_logical_and(expr
))
176 __use_cond_false_states();
178 __push_cond_stacks();
180 __save_pre_cond_states();
181 split_conditions(expr
->right
);
182 __process_post_op_stack();
183 __discard_pre_cond_states();
185 if (is_logical_and(expr
))
190 __use_cond_true_states();
193 static struct AVL
*combine_strees(struct AVL
*orig
, struct AVL
*fake
, struct AVL
*new)
195 struct AVL
*ret
= NULL
;
197 overwrite_stree(orig
, &ret
);
198 overwrite_stree(fake
, &ret
);
199 overwrite_stree(new, &ret
);
207 * if ((aaa()?bbb():ccc())) { ...
209 * This is almost the same as:
210 * if ((aaa() && bbb()) || (!aaa() && ccc())) { ...
212 * It's a bit complicated because we shouldn't pass aaa()
213 * to the clients more than once.
216 static void handle_select(struct expression
*expr
)
218 struct AVL
*a_T
= NULL
;
219 struct AVL
*a_F
= NULL
;
220 struct AVL
*a_T_b_T
= NULL
;
221 struct AVL
*a_T_b_F
= NULL
;
222 struct AVL
*a_T_b_fake
= NULL
;
223 struct AVL
*a_F_c_T
= NULL
;
224 struct AVL
*a_F_c_F
= NULL
;
225 struct AVL
*a_F_c_fake
= NULL
;
229 * Imagine we have this: if (a ? b : c) { ...
231 * The condition is true if "a" is true and "b" is true or
232 * "a" is false and "c" is true. It's false if "a" is true
233 * and "b" is false or "a" is false and "c" is false.
235 * The variable name "a_T_b_T" stands for "a true b true" etc.
237 * But if we know "b" is true then we can simpilify things.
238 * The condition is true if "a" is true or if "a" is false and
239 * "c" is true. The only way the condition can be false is if
240 * "a" is false and "c" is false.
242 * The remaining thing is the "a_T_b_fake". When we simplify
243 * the equations we have to take into consideration that other
244 * states may have changed that don't play into the true false
245 * equation. Take the following example:
247 * (flags) = __raw_local_irq_save();
248 * _spin_trylock(lock) ? 1 :
249 * ({ raw_local_irq_restore(flags); 0; });
251 * Smatch has to record that the irq flags were restored on the
256 __save_pre_cond_states();
258 split_conditions(expr
->conditional
);
260 a_T
= __copy_cond_true_states();
261 a_F
= __copy_cond_false_states();
263 __push_cond_stacks();
264 __push_fake_cur_slist();
265 split_conditions(expr
->cond_true
);
266 __process_post_op_stack();
267 a_T_b_fake
= __pop_fake_cur_slist();
268 a_T_b_T
= combine_strees(a_T
, a_T_b_fake
, __pop_cond_true_stack());
269 a_T_b_F
= combine_strees(a_T
, a_T_b_fake
, __pop_cond_false_stack());
271 __use_cond_false_states();
273 __push_cond_stacks();
274 __push_fake_cur_slist();
275 split_conditions(expr
->cond_false
);
276 a_F_c_fake
= __pop_fake_cur_slist();
277 a_F_c_T
= combine_strees(a_F
, a_F_c_fake
, __pop_cond_true_stack());
278 a_F_c_F
= combine_strees(a_F
, a_F_c_fake
, __pop_cond_false_stack());
280 /* We have to restore the pre condition states so that
281 implied_condition_true() will use the right cur_stree */
282 __use_pre_cond_states();
284 if (implied_condition_true(expr
->cond_true
)) {
285 free_stree(&a_T_b_T
);
286 free_stree(&a_T_b_F
);
287 a_T_b_T
= clone_stree(a_T
);
288 overwrite_stree(a_T_b_fake
, &a_T_b_T
);
290 if (implied_condition_false(expr
->cond_true
)) {
291 free_stree(&a_T_b_T
);
292 free_stree(&a_T_b_F
);
293 a_T_b_F
= clone_stree(a_T
);
294 overwrite_stree(a_T_b_fake
, &a_T_b_F
);
296 if (implied_condition_true(expr
->cond_false
)) {
297 free_stree(&a_F_c_T
);
298 free_stree(&a_F_c_F
);
299 a_F_c_T
= clone_stree(a_F
);
300 overwrite_stree(a_F_c_fake
, &a_F_c_T
);
302 if (implied_condition_false(expr
->cond_false
)) {
303 free_stree(&a_F_c_T
);
304 free_stree(&a_F_c_F
);
305 a_F_c_F
= clone_stree(a_F
);
306 overwrite_stree(a_F_c_fake
, &a_F_c_F
);
309 merge_stree(&a_T_b_T
, a_F_c_T
);
310 merge_stree(&a_T_b_F
, a_F_c_F
);
312 __pop_cond_true_stack();
313 __pop_cond_false_stack();
314 __push_cond_stacks();
315 FOR_EACH_SM(a_T_b_T
, sm
) {
316 __set_true_false_sm(sm
, NULL
);
317 } END_FOR_EACH_SM(sm
);
318 FOR_EACH_SM(a_T_b_F
, sm
) {
319 __set_true_false_sm(NULL
, sm
);
320 } END_FOR_EACH_SM(sm
);
322 free_stree(&a_T_b_fake
);
323 free_stree(&a_F_c_fake
);
326 static int make_op_unsigned(int op
)
330 return SPECIAL_UNSIGNED_LT
;
332 return SPECIAL_UNSIGNED_LTE
;
334 return SPECIAL_UNSIGNED_GT
;
336 return SPECIAL_UNSIGNED_GTE
;
341 static void hackup_unsigned_compares(struct expression
*expr
)
343 if (expr
->type
!= EXPR_COMPARE
)
346 if (type_unsigned(get_type(expr
)))
347 expr
->op
= make_op_unsigned(expr
->op
);
350 static void split_conditions(struct expression
*expr
)
353 char *cond
= expr_to_str(expr
);
355 sm_debug("%d in split_conditions (%s)\n", get_lineno(), cond
);
359 expr
= strip_expr(expr
);
363 switch (expr
->type
) {
365 __pass_to_client(expr
, LOGIC_HOOK
);
366 handle_logical(expr
);
369 hackup_unsigned_compares(expr
);
370 if (handle_zero_comparisons(expr
))
374 if (ignore_builtin_expect(expr
))
378 if (handle_preop(expr
))
381 case EXPR_CONDITIONAL
:
387 /* fixme: this should be in smatch_flow.c
388 but because of the funny stuff we do with conditions
389 it's awkward to put it there. We would need to
390 call CONDITION_HOOK in smatch_flow as well.
392 push_expression(&big_expression_stack
, expr
);
393 if (expr
->type
== EXPR_COMPARE
) {
394 if (expr
->left
->type
!= EXPR_POSTOP
)
395 __split_expr(expr
->left
);
396 if (expr
->right
->type
!= EXPR_POSTOP
)
397 __split_expr(expr
->right
);
398 } else if (expr
->type
!= EXPR_POSTOP
) {
401 __pass_to_client(expr
, CONDITION_HOOK
);
402 if (expr
->type
== EXPR_COMPARE
) {
403 if (expr
->left
->type
== EXPR_POSTOP
)
404 __split_expr(expr
->left
);
405 if (expr
->right
->type
== EXPR_POSTOP
)
406 __split_expr(expr
->right
);
407 } else if (expr
->type
== EXPR_POSTOP
) {
410 __process_post_op_stack();
411 pop_expression(&big_expression_stack
);
414 static int inside_condition
;
415 void __split_whole_condition(struct expression
*expr
)
417 sm_debug("%d in __split_whole_condition\n", get_lineno());
419 __save_pre_cond_states();
420 __push_cond_stacks();
421 /* it's a hack, but it's sometimes handy to have this stuff
422 on the big_expression_stack. */
423 push_expression(&big_expression_stack
, expr
);
425 split_conditions(expr
);
427 __pass_to_client(expr
, WHOLE_CONDITION_HOOK
);
428 pop_expression(&big_expression_stack
);
430 sm_debug("%d done __split_whole_condition\n", get_lineno());
433 void __handle_logic(struct expression
*expr
)
435 sm_debug("%d in __handle_logic\n", get_lineno());
437 __save_pre_cond_states();
438 __push_cond_stacks();
439 /* it's a hack, but it's sometimes handy to have this stuff
440 on the big_expression_stack. */
441 push_expression(&big_expression_stack
, expr
);
443 split_conditions(expr
);
445 __pass_to_client(expr
, WHOLE_CONDITION_HOOK
);
446 pop_expression(&big_expression_stack
);
447 __merge_false_states();
449 sm_debug("%d done __handle_logic\n", get_lineno());
452 int is_condition(struct expression
*expr
)
455 expr
= strip_expr(expr
);
459 switch (expr
->type
) {
470 int __handle_condition_assigns(struct expression
*expr
)
472 struct expression
*right
;
474 right
= strip_expr(expr
->right
);
475 if (!is_condition(expr
->right
))
478 sm_debug("%d in __handle_condition_assigns\n", get_lineno());
480 __save_pre_cond_states();
481 __push_cond_stacks();
482 /* it's a hack, but it's sometimes handy to have this stuff
483 on the big_expression_stack. */
484 push_expression(&big_expression_stack
, right
);
485 split_conditions(right
);
487 set_extra_expr_mod(expr
->left
, alloc_estate_sval(sval_type_val(get_type(expr
->left
), 1)));
488 __pass_to_client(right
, WHOLE_CONDITION_HOOK
);
489 pop_expression(&big_expression_stack
);
491 sm_debug("%d done __handle_condition_assigns\n", get_lineno());
493 __push_true_states();
494 __use_false_states();
495 set_extra_expr_mod(expr
->left
, alloc_estate_sval(sval_type_val(get_type(expr
->left
), 0)));
496 __merge_true_states();
497 __pass_to_client(expr
, ASSIGNMENT_HOOK
);
501 static int is_select_assign(struct expression
*expr
)
503 struct expression
*right
;
507 right
= strip_expr(expr
->right
);
508 if (right
->type
== EXPR_CONDITIONAL
)
510 if (right
->type
== EXPR_SELECT
)
515 static void set_fake_assign(struct expression
*new,
516 struct expression
*left
, int op
, struct expression
*right
)
519 new->pos
= left
->pos
;
521 new->type
= EXPR_ASSIGNMENT
;
526 int __handle_select_assigns(struct expression
*expr
)
528 struct expression
*right
;
529 struct AVL
*final_states
= NULL
;
534 if (!is_select_assign(expr
))
536 sm_debug("%d in __handle_ternary_assigns\n", get_lineno());
537 right
= strip_expr(expr
->right
);
539 is_true
= implied_condition_true(right
->conditional
);
540 is_false
= implied_condition_false(right
->conditional
);
542 /* hah hah. the ultra fake out */
543 __save_pre_cond_states();
544 __split_whole_condition(right
->conditional
);
547 struct expression fake_expr
;
549 if (right
->cond_true
)
550 set_fake_assign(&fake_expr
, expr
->left
, expr
->op
, right
->cond_true
);
552 set_fake_assign(&fake_expr
, expr
->left
, expr
->op
, right
->conditional
);
553 __split_expr(&fake_expr
);
554 final_states
= clone_stree(__get_cur_stree());
557 __use_false_states();
559 struct expression fake_expr
;
561 set_fake_assign(&fake_expr
, expr
->left
, expr
->op
, right
->cond_false
);
562 __split_expr(&fake_expr
);
563 merge_stree(&final_states
, __get_cur_stree());
566 __use_pre_cond_states();
568 FOR_EACH_SM(final_states
, sm
) {
570 } END_FOR_EACH_SM(sm
);
572 free_stree(&final_states
);
574 sm_debug("%d done __handle_ternary_assigns\n", get_lineno());
579 static struct statement
*split_then_return_last(struct statement
*stmt
)
581 struct statement
*tmp
;
582 struct statement
*last_stmt
;
584 last_stmt
= last_ptr_list((struct ptr_list
*)stmt
->stmts
);
588 __push_scope_hooks();
589 FOR_EACH_PTR(stmt
->stmts
, tmp
) {
590 if (tmp
== last_stmt
)
593 } END_FOR_EACH_PTR(tmp
);
597 int __handle_expr_statement_assigns(struct expression
*expr
)
599 struct expression
*right
;
600 struct statement
*stmt
;
603 if (right
->type
== EXPR_PREOP
&& right
->op
== '(')
605 if (right
->type
!= EXPR_STATEMENT
)
609 stmt
= right
->statement
;
610 if (stmt
->type
== STMT_COMPOUND
) {
611 struct statement
*last_stmt
;
612 struct expression fake_assign
;
613 struct expression fake_expr_stmt
;
615 last_stmt
= split_then_return_last(stmt
);
621 fake_expr_stmt
.pos
= last_stmt
->pos
;
622 fake_expr_stmt
.type
= EXPR_STATEMENT
;
623 fake_expr_stmt
.statement
= last_stmt
;
625 fake_assign
.pos
= last_stmt
->pos
;
626 fake_assign
.op
= expr
->op
;
627 fake_assign
.type
= EXPR_ASSIGNMENT
;
628 fake_assign
.left
= expr
->left
;
629 fake_assign
.right
= &fake_expr_stmt
;
631 __split_expr(&fake_assign
);
633 __call_scope_hooks();
634 } else if (stmt
->type
== STMT_EXPRESSION
) {
635 struct expression fake_assign
;
637 fake_assign
.pos
= stmt
->pos
;
638 fake_assign
.op
= expr
->op
;
639 fake_assign
.type
= EXPR_ASSIGNMENT
;
640 fake_assign
.left
= expr
->left
;
641 fake_assign
.right
= stmt
->expression
;
643 __split_expr(&fake_assign
);
652 int in_condition(void)
654 return inside_condition
;