tree c15b578a13f05f35ad3c0367e836d30dfafaae7a
parent 34f69633bfdcf9db92f698f8487115767eebef81
author Lynn Boger <laboger@linux.vnet.ibm.com> 1568729642 -0400
committer Lynn Boger <laboger@linux.vnet.ibm.com> 1570733667 +0000

internal/chacha20: improve chacha20 performance on ppc64le

This improves the performance of the asm implementation for
chacha20 on ppc64le by updating to the vsx implementation
provided in cryptogams. The previous implementation was found to
not perform as well as possible on power9. This implementation
improves performance on both power8 and power9.

Power9 improvement with this change as compared to current:

name               old time/op    new time/op     delta
ChaCha20/32-64        361ns ± 0%      225ns ± 0%  -37.67%  (p=1.000 n=1+1)
ChaCha20/63-64        364ns ± 0%      229ns ± 0%  -37.09%  (p=1.000 n=1+1)
ChaCha20/64-64        364ns ± 0%      231ns ± 0%  -36.54%  (p=1.000 n=1+1)
ChaCha20/256-64       332ns ± 0%      199ns ± 0%  -40.06%  (p=1.000 n=1+1)
ChaCha20/1024-64     1.24µs ± 0%     0.70µs ± 0%  -43.23%  (p=1.000 n=1+1)
ChaCha20/1350-64     1.89µs ± 0%     1.03µs ± 0%  -45.35%  (p=1.000 n=1+1)
ChaCha20/65536-64    77.0µs ± 0%     42.5µs ± 0%  -44.83%  (p=1.000 n=1+1)

This is discussed in issue golang/go#25051.

A few asm instructions vmrgew and vmrgow were just added in Go 1.14
so have been encoded using WORD at this point.

Change-Id: I2b192a63cf46b0b20195e60e4412c43c5dd14ad8
Reviewed-on: https://go-review.googlesource.com/c/crypto/+/195959
Run-TryBot: Lynn Boger <laboger@linux.vnet.ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Carlos Eduardo Seo <cseo@linux.vnet.ibm.com>