Re: [PATCH] Hex-coding optimizations using SVE on ARM.

On Tue, Jan 14, 2025 at 11:57 PM Nathan Bossart
<nathandbossart(at)gmail(dot)com> wrote:
>
> On Tue, Jan 14, 2025 at 12:59:04AM -0500, Tom Lane wrote:
> > John Naylor <johncnaylorls(at)gmail(dot)com> writes:
> >> We can do about as well simply by changing the nibble lookup to a byte
> >> lookup, which works on every compiler and architecture:
>
> Nice. I tried enabling auto-vectorization and loop unrolling on top of
> this patch, and the numbers looked the same. I think we'd need CPU
> intrinsics or an even bigger lookup table to do any better.

Thanks for looking further! Yeah, I like that the table is still only 512 bytes.

> > I didn't attempt to verify your patch, but I do prefer addressing
> > this issue in a machine-independent fashion. I also like the brevity
> > of the patch (though it could do with some comments perhaps, not that
> > the existing code has any).
>
> +1

Okay, I added a comment. I also agree with Michael that my quick
one-off was a bit hard to read so I've cleaned it up a bit. I plan to
commit the attached by Friday, along with any bikeshedding that
happens by then.

--
John Naylor
Amazon Web Services