This is tiny optimization for growslice, which is probably too small to
measure easily.
Move the for loop to avoid multiple checks inside the loop.
Also, use >> 2 instead of /4, which generates fewer instructions.
Change-Id: I9ab09bdccb56f98ab22073f23d9e102c252238c7
Reviewed-on: https://go-review.googlesource.com/c/go/+/493795 Reviewed-by: Keith Randall <khr@golang.org> Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Egon Elbre <egonelbre@gmail.com>
Auto-Submit: Ian Lance Taylor <iant@golang.org> Reviewed-by: Keith Randall <khr@google.com>