From: Michel Lespinasse <walken@google.com>
To: riel@redhat.com, peterz@infradead.org, daniel.santos@pobox.com,
aarcange@redhat.com, dwmw2@infradead.org,
akpm@linux-foundation.org
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
torvalds@linux-foundation.org
Subject: [PATCH v3 3/9] rbtree: place easiest case first in rb_erase()
Date: Mon, 20 Aug 2012 15:05:25 -0700 [thread overview]
Message-ID: <1345500331-10546-4-git-send-email-walken@google.com> (raw)
In-Reply-To: <1345500331-10546-1-git-send-email-walken@google.com>
In rb_erase, move the easy case (node to erase has no more than
1 child) first. I feel the code reads easier that way.
Signed-off-by: Michel Lespinasse <walken@google.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
---
lib/rbtree.c | 35 ++++++++++++++++++-----------------
1 files changed, 18 insertions(+), 17 deletions(-)
diff --git a/lib/rbtree.c b/lib/rbtree.c
index de89a614b1ba..bde1b5c5fb33 100644
--- a/lib/rbtree.c
+++ b/lib/rbtree.c
@@ -368,17 +368,28 @@ static void __rb_erase_color(struct rb_node *node, struct rb_node *parent,
void rb_erase(struct rb_node *node, struct rb_root *root)
{
- struct rb_node *child, *parent;
+ struct rb_node *child = node->rb_right, *tmp = node->rb_left;
+ struct rb_node *parent;
int color;
- if (!node->rb_left)
- child = node->rb_right;
- else if (!node->rb_right)
- child = node->rb_left;
- else {
+ if (!tmp) {
+ case1:
+ /* Case 1: node to erase has no more than 1 child (easy!) */
+
+ parent = rb_parent(node);
+ color = rb_color(node);
+
+ if (child)
+ rb_set_parent(child, parent);
+ __rb_change_child(node, child, parent, root);
+ } else if (!child) {
+ /* Still case 1, but this time the child is node->rb_left */
+ child = tmp;
+ goto case1;
+ } else {
struct rb_node *old = node, *left;
- node = node->rb_right;
+ node = child;
while ((left = node->rb_left) != NULL)
node = left;
@@ -402,18 +413,8 @@ void rb_erase(struct rb_node *node, struct rb_root *root)
node->__rb_parent_color = old->__rb_parent_color;
node->rb_left = old->rb_left;
rb_set_parent(old->rb_left, node);
-
- goto color;
}
- parent = rb_parent(node);
- color = rb_color(node);
-
- if (child)
- rb_set_parent(child, parent);
- __rb_change_child(node, child, parent, root);
-
-color:
if (color == RB_BLACK)
__rb_erase_color(child, parent, root);
}
--
1.7.7.3
--
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next prev parent reply other threads:[~2012-08-20 22:05 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-20 22:05 [PATCH v3 0/9] faster augmented rbtree interface Michel Lespinasse
2012-08-20 22:05 ` [PATCH v3 1/9] rbtree test: fix sparse warning about 64-bit constant Michel Lespinasse
2012-08-20 22:05 ` [PATCH v3 2/9] rbtree: add __rb_change_child() helper function Michel Lespinasse
2012-08-20 22:17 ` Andrew Morton
2012-08-23 12:05 ` Jan Engelhardt
2012-08-23 13:08 ` David Woodhouse
2012-09-26 22:34 ` Daniel Santos
2012-09-26 22:43 ` Andrew Morton
2012-08-20 22:05 ` Michel Lespinasse [this message]
2012-08-20 22:28 ` [PATCH v3 3/9] rbtree: place easiest case first in rb_erase() Andrew Morton
2012-08-20 22:05 ` [PATCH v3 4/9] rbtree: handle 1-child recoloring in rb_erase() instead of rb_erase_color() Michel Lespinasse
2012-08-20 22:05 ` [PATCH v3 5/9] rbtree: low level optimizations in rb_erase() Michel Lespinasse
2012-08-20 22:05 ` [PATCH v3 6/9] rbtree: augmented rbtree test Michel Lespinasse
2012-08-20 22:05 ` [PATCH v3 7/9] rbtree: faster augmented rbtree manipulation Michel Lespinasse
2012-08-20 22:05 ` [PATCH v3 8/9] rbtree: remove prior augmented rbtree implementation Michel Lespinasse
2012-08-20 22:05 ` [PATCH v3 9/9] rbtree: add RB_DECLARE_CALLBACKS() macro Michel Lespinasse
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