From dc79206aec20b92388e7050d0359dccccd31ef0b Mon Sep 17 00:00:00 2001
From: Iskander Sharipov <iskander.sharipov@intel.com>
Date: Sat, 9 Jun 2018 20:43:54 +0300
Subject: [PATCH] net: combine append calls in reverseaddr
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Combined appends lead to fewer machine code and faster performance.
Some may even say that it makes code more readable.

Running revAddrTests over reverseaddr gives measurable improvements:

	name              old time/op  new time/op  delta
	ReverseAddress-8  4.10µs ± 3%  3.94µs ± 1%  -3.81%  (p=0.000 n=10+9)

Change-Id: I9bda7a20f802bcdffc6e948789765d04c6da04e7
Reviewed-on: https://go-review.googlesource.com/117615
Run-TryBot: Iskander Sharipov <iskander.sharipov@intel.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
---
 src/net/dnsclient.go | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/net/dnsclient.go b/src/net/dnsclient.go
index 2e4bffaab8..e3524280b6 100644
--- a/src/net/dnsclient.go
+++ b/src/net/dnsclient.go
@@ -27,10 +27,10 @@ func reverseaddr(addr string) (arpa string, err error) {
 	// Add it, in reverse, to the buffer
 	for i := len(ip) - 1; i >= 0; i-- {
 		v := ip[i]
-		buf = append(buf, hexDigit[v&0xF])
-		buf = append(buf, '.')
-		buf = append(buf, hexDigit[v>>4])
-		buf = append(buf, '.')
+		buf = append(buf, hexDigit[v&0xF],
+			'.',
+			hexDigit[v>>4],
+			'.')
 	}
 	// Append "ip6.arpa." and return (buf already has the final .)
 	buf = append(buf, "ip6.arpa."...)
-- 
2.50.0