From 29717eb02920eda35c810b444f7fa7b190155170 Mon Sep 17 00:00:00 2001
From: Jilles Tjoelker <jilles@FreeBSD.org>
Date: Thu, 18 May 2017 22:10:04 +0000
Subject: [PATCH] sh: Keep output buffer across builtins.

Allocating and deallocating repeatedly the 1024-byte buffer for stdout from
builtins costs CPU time for little or no benefit.

A simple loop containing builtins that write to a file descriptor, such as
  i=0; while [ "$i" -lt 1000000 ]; do printf .; i=$((i+1)); done >/dev/null
is over 10% faster in a simple benchmark on an amd64 virtual machine.
---
 bin/sh/output.c | 9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

diff --git a/bin/sh/output.c b/bin/sh/output.c
index c3458272785e..ced01d246a1c 100644
--- a/bin/sh/output.c
+++ b/bin/sh/output.c
@@ -254,14 +254,7 @@ flushout(struct output *dest)
 void
 freestdout(void)
 {
-	INTOFF;
-	if (output.buf) {
-		ckfree(output.buf);
-		output.nextc = NULL;
-		output.buf = NULL;
-		output.bufend = NULL;
-	}
-	INTON;
+	output.nextc = output.buf;
 }