From 443c2d5442edf78a5b91ed13e756e21ea30a5bb1 Mon Sep 17 00:00:00 2001
From: Gareth Ellis <gareth.ellis@uk.ibm.com>
Date: Mon, 21 Mar 2016 09:46:42 +0000
Subject: [PATCH] buffer: changing let in for loops back to var

Using let in for loops showed a regression in 4.4.0. @ofrobots
suggested that we avoid using let in for loops until TurboFan becomes
the default optimiser.

The regression that was detected was when looking at how long it took
to create a new buffer from an array of data.

When using `for (let i=0; i<length; i++) ` we saw the operation take
almost 40% longer compared to `var i=0`.

PR-URL: https://github.com/nodejs/node/pull/5819
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>
Reviewed-By: Trevor Norris <trevnorris@gmail.com>
Reviewed-By: Myles Borins <myles.borins@gmail.com>
Ref: http://github.com/nodejs/benchmarking/issues/38
---
 lib/buffer.js | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/lib/buffer.js b/lib/buffer.js
index 01a8f303e1..b138552ef9 100644
--- a/lib/buffer.js
+++ b/lib/buffer.js
@@ -185,7 +185,7 @@ function fromString(string, encoding) {
 function fromArrayLike(obj) {
   const length = obj.length;
   const b = allocate(length);
-  for (let i = 0; i < length; i++)
+  for (var i = 0; i < length; i++)
     b[i] = obj[i] & 255;
   return b;
 }
@@ -276,6 +276,7 @@ Buffer.isEncoding = function(encoding) {
 
 
 Buffer.concat = function(list, length) {
+  var i;
   if (!Array.isArray(list))
     throw new TypeError('"list" argument must be an Array of Buffers');
 
@@ -284,7 +285,7 @@ Buffer.concat = function(list, length) {
 
   if (length === undefined) {
     length = 0;
-    for (let i = 0; i < list.length; i++)
+    for (i = 0; i < list.length; i++)
       length += list[i].length;
   } else {
     length = length >>> 0;
@@ -292,7 +293,7 @@ Buffer.concat = function(list, length) {
 
   var buffer = Buffer.allocUnsafe(length);
   var pos = 0;
-  for (let i = 0; i < list.length; i++) {
+  for (i = 0; i < list.length; i++) {
     var buf = list[i];
     if (!Buffer.isBuffer(buf))
       throw new TypeError('"list" argument must be an Array of Buffers');