diff options
| author | Wolfram Strepp <wstrepp@gmx.de> | 2009-04-01 02:23:45 +0400 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-04-01 19:59:17 +0400 |
| commit | 55a63998b8967615a15e2211ba0ff3a84a565824 (patch) | |
| tree | a83905577b60496a3ea9174bf29596f927354746 /lib | |
| parent | 53d6660836f233df66490707365ab177e5fb2bb4 (diff) | |
| download | linux-55a63998b8967615a15e2211ba0ff3a84a565824.tar.xz | |
lib/rbtree.c: optimize rb_erase()
Tfour 4 redundant if-conditions in function __rb_erase_color() in
lib/rbtree.c are removed.
In pseudo-source-code, the structure of the code is as follows:
if ((!A || B) && (!C || D)) {
.
.
.
} else {
if (!C || D) {//if this is true, it implies: (A == true) && (B == false)
if (A) {//hence this always evaluates to 'true'...
.
}
.
//at this point, C always becomes true, because of:
__rb_rotate_right/left();
//and:
other = parent->rb_right/left;
}
.
.
if (C) {//...and this too !
.
}
}
Signed-off-by: Wolfram Strepp <wstrepp@gmx.de>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andrea Arcangeli <andrea@qumranet.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/rbtree.c | 14 |
1 files changed, 4 insertions, 10 deletions
diff --git a/lib/rbtree.c b/lib/rbtree.c index 9956b99649f0..f653659e0bc1 100644 --- a/lib/rbtree.c +++ b/lib/rbtree.c @@ -163,17 +163,14 @@ static void __rb_erase_color(struct rb_node *node, struct rb_node *parent, { if (!other->rb_right || rb_is_black(other->rb_right)) { - struct rb_node *o_left; - if ((o_left = other->rb_left)) - rb_set_black(o_left); + rb_set_black(other->rb_left); rb_set_red(other); __rb_rotate_right(other, root); other = parent->rb_right; } rb_set_color(other, rb_color(parent)); rb_set_black(parent); - if (other->rb_right) - rb_set_black(other->rb_right); + rb_set_black(other->rb_right); __rb_rotate_left(parent, root); node = root->rb_node; break; @@ -200,17 +197,14 @@ static void __rb_erase_color(struct rb_node *node, struct rb_node *parent, { if (!other->rb_left || rb_is_black(other->rb_left)) { - register struct rb_node *o_right; - if ((o_right = other->rb_right)) - rb_set_black(o_right); + rb_set_black(other->rb_right); rb_set_red(other); __rb_rotate_left(other, root); other = parent->rb_left; } rb_set_color(other, rb_color(parent)); rb_set_black(parent); - if (other->rb_left) - rb_set_black(other->rb_left); + rb_set_black(other->rb_left); __rb_rotate_right(parent, root); node = root->rb_node; break; |