[PATCH 1/3] Further optimization of function rb_erase() inlib/rbtree.c

[Wolfram Strepp]

This small patch-series reorganizes some lines in function rb_erase()
in lib/rbtree.c, and as a result one if-condition can be omitted.
Tested on x86.


First, move some code around in order to make the next change more obvious.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Signed-off-by: Wolfram Strepp <wstrepp@xxxxxx>

---
 lib/rbtree.c |   19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)
Index: linux-2.6/lib/rbtree.c
===================================================================
--- linux-2.6.orig/lib/rbtree.c
+++ linux-2.6/lib/rbtree.c
@@ -237,6 +237,16 @@ void rb_erase(struct rb_node *node, stru
 		node = node->rb_right;
 		while ((left = node->rb_left) != NULL)
 			node = left;
+
+		if (rb_parent(old))
+		{
+			if (rb_parent(old)->rb_left == old)
+				rb_parent(old)->rb_left = node;
+			else
+				rb_parent(old)->rb_right = node;
+		} else
+			root->rb_node = node;
+
 		child = node->rb_right;
 		parent = rb_parent(node);
 		color = rb_color(node);
@@ -253,15 +263,6 @@ void rb_erase(struct rb_node *node, stru
 		node->rb_right = old->rb_right;
 		node->rb_left = old->rb_left;
 
-		if (rb_parent(old))
-		{
-			if (rb_parent(old)->rb_left == old)
-				rb_parent(old)->rb_left = node;
-			else
-				rb_parent(old)->rb_right = node;
-		} else
-			root->rb_node = node;
-
 		rb_set_parent(old->rb_left, node);
 		if (old->rb_right)
 			rb_set_parent(old->rb_right, node);

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