From: ebiggers@kernel.org (Eric Biggers)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] crypto: arm/chacha20 - faster 8-bit rotations and other optimizations
Date: Fri, 31 Aug 2018 23:42:17 -0700 [thread overview]
Message-ID: <20180901064216.GB6466@sol.localdomain> (raw)
In-Reply-To: <CAKv+Gu-KAbGo3MKNkz26o5qG13283AY6vNrrCLwyi8KQR0Vc0w@mail.gmail.com>
On Fri, Aug 31, 2018 at 06:51:34PM +0200, Ard Biesheuvel wrote:
> >>
> >> + adr ip, .Lrol8_table
> >> mov r3, #10
> >>
> >> .Ldoubleround4:
> >> @@ -238,24 +268,25 @@ ENTRY(chacha20_4block_xor_neon)
> >> // x1 += x5, x13 = rotl32(x13 ^ x1, 8)
> >> // x2 += x6, x14 = rotl32(x14 ^ x2, 8)
> >> // x3 += x7, x15 = rotl32(x15 ^ x3, 8)
> >> + vld1.8 {d16}, [ip, :64]
>
> Also, would it perhaps be more efficient to keep the rotation vector
> in a pair of GPRs, and use something like
>
> vmov d16, r4, r5
>
> here?
>
I tried that, but it doesn't help on either Cortex-A7 or Cortex-A53.
In fact it's very slightly worse.
- Eric
next prev parent reply other threads:[~2018-09-01 6:42 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-31 8:01 [PATCH] crypto: arm/chacha20 - faster 8-bit rotations and other optimizations Eric Biggers
2018-08-31 15:56 ` Ard Biesheuvel
2018-08-31 16:51 ` Ard Biesheuvel
2018-09-01 6:42 ` Eric Biggers [this message]
2018-09-01 6:39 ` Eric Biggers
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