tree dd0b491b58e574a25b67ab5a8e32bbebe99c2a8c
parent 41fd8d6401b6702b801678a493001ec9e08d6f2d
author Ilya Tocar <ilya.tocar@intel.com> 1490728168 -0500
committer Ilya Tocar <ilya.tocar@intel.com> 1490819789 +0000

math: speed up Log on amd64

After https://golang.org/cl/31490 we break false
output dependency for CVTS.. in compiler generated code.
I've looked through asm code, which uses CVTS..
and added XOR to the only case where it affected performance.

Log-6                  21.6ns ± 0%  19.9ns ± 0%  -7.87%  (p=0.000 n=10+10)

Change-Id: I25d9b405e3041a3839b40f9f9a52e708034bb347
Reviewed-on: https://go-review.googlesource.com/38771
Run-TryBot: Ilya Tocar <ilya.tocar@intel.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>