Re: [AArch64][PATCH 1/2] Make AES unspecs commutative

[Kyrill Tkachov <kyrylo dot tkachov at foss dot arm dot com>]

Hi Andre,

On 18/06/18 10:38, Andre Simoes Dias Vieira wrote:
> Hi,
>
> This patch teaches the AArch64 backend that the AESE and AESD unspecs are commutative (which correspond to the vaeseq_u8 and vaesdq_u8 intrinsics). This improves register allocation around their corresponding instructions avoiding unnecessary moves.
>
> For instance, with the old patterns code such as:
>
> uint8x16_t
> test0 (uint8x16_t a, uint8x16_t b)
> {
>   uint8x16_t result;
>   result = vaeseq_u8 (a, b);
>   result = vaeseq_u8 (result, a);
>   return result;
> }
>
> would lead to suboptimal register allocation such as:
> test0:
>         mov     v2.16b, v0.16b
>         aese    v2.16b, v1.16b
>         mov     v1.16b, v2.16b
>         aese    v1.16b, v0.16b
>         mov     v0.16b, v1.16b
>         ret
>
> whereas with the new patterns we see:
>         aese    v1.16b, v0.16b
>         aese    v0.16b, v1.16b
>         ret
>
>
> Bootstrapped and tested on aarch64-none-linux-gnu.
>
> Is this OK for trunk?

Nice one!
Do you think we can get an equivalent patch for arm?

Thanks,
Kyrill

> Cheers,
> Andre
>
>
> gcc
> 2018-06-18  Andre Vieira <andre.simoesdiasvieira@arm.com>
>
>
>         * config/aarch64/aarch64-simd.md (aarch64_crypto_aes<aes_op>v16qi):
>         Make operands of the unspec commutative.
>
> gcc/testsuite
> 2018-06-18 Andre Vieira <andre.simoesdiasvieira@arm.com>
>
>         * gcc/target/aarch64/aes_2.c: New test.