Date: Tue, 14 Jan 2025 10:57:51 -0600
From: Nathan Bossart <nathandbossart@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: John Naylor <johncnaylorls@gmail.com>,
	"Chiranmoy.Bhattacharya@fujitsu.com" <Chiranmoy.Bhattacharya@fujitsu.com>,
	"Devanga.Susmitha@fujitsu.com" <Devanga.Susmitha@fujitsu.com>,
	"pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>,
	"Ragesh.Hajela@fujitsu.com" <Ragesh.Hajela@fujitsu.com>
Subject: Re: [PATCH] Hex-coding optimizations using SVE on ARM.
Message-ID: <Z4aXj_fJYCQ6GBbC@nathan>
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On Tue, Jan 14, 2025 at 12:59:04AM -0500, Tom Lane wrote:
> John Naylor <johncnaylorls@gmail.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.

> 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

-- 
nathan