tree 969d007a0e310df537f7f9495b353bbad4e984d4
parent 04904a0fff639c058d38b355d75485ca5dde0a89
author Daniel Hu <Daniel.Hu@arm.com> 1644229026 +0000
committer Pauli <pauli@openssl.org> 1651552666 +1000

Acceleration of chacha20 on aarch64 by SVE

This patch accelerates chacha20 on aarch64 when Scalable Vector Extension
(SVE) is supported by CPU. Tested on modern micro-architecture with
256-bit SVE, it has the potential to improve performance up to 20%

The solution takes a hybrid approach. SVE will handle multi-blocks that fit
the SVE vector length, with Neon/Scalar to process any tail data

Test result:
With SVE
type            1024 bytes   8192 bytes  16384 bytes
ChaCha20        1596208.13k  1650010.79k  1653151.06k

Without SVE (by Neon/Scalar)
type            1024 bytes   8192 bytes  16384 bytes
chacha20        1355487.91k  1372678.83k  1372662.44k

The assembly code has been reviewed internally by
ARM engineer Fangming.Fang@arm.com

Signed-off-by: Daniel Hu <Daniel.Hu@arm.com>

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/17916)