From: Nathan Bossart <nathandbossart@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: John Naylor <johncnaylorls@gmail.com>
Cc: Chiranmoy.Bhattacharya@fujitsu.com <Chiranmoy.Bhattacharya@fujitsu.com>
Cc: Devanga.Susmitha@fujitsu.com <Devanga.Susmitha@fujitsu.com>
Cc: pgsql-hackers@postgresql.org <pgsql-hackers@postgresql.org>
Cc: Ragesh.Hajela@fujitsu.com <Ragesh.Hajela@fujitsu.com>
Subject: Re: [PATCH] Hex-coding optimizations using SVE on ARM.
Date: Tue, 14 Jan 2025 10:57:51 -0600
Message-ID: <Z4aXj_fJYCQ6GBbC@nathan> (raw)
In-Reply-To: <622082.1736834344@sss.pgh.pa.us>
References: <OSZPR01MB8499D4884C4541159FA00ECC8B132@OSZPR01MB8499.jpnprd01.prod.outlook.com>
<Z4AUr-Y-TPaqtg0y@nathan>
<OSBPR01MB26648F7B60A543069C75EC43971C2@OSBPR01MB2664.jpnprd01.prod.outlook.com>
<Z4E-5oQGux-2R4iL@nathan>
<Z4GHNfhRKuA0r_Wn@nathan>
<CANWCAZZvXuJMgqMN4u068Yqa19CEjS31tQKZp_qFFFbgYfaXqQ@mail.gmail.com>
<622082.1736834344@sss.pgh.pa.us>
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
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Cc: nathandbossart@gmail.com, tgl@sss.pgh.pa.us, johncnaylorls@gmail.com, Chiranmoy.Bhattacharya@fujitsu.com, Devanga.Susmitha@fujitsu.com, Ragesh.Hajela@fujitsu.com
Subject: Re: [PATCH] Hex-coding optimizations using SVE on ARM.
In-Reply-To: <Z4aXj_fJYCQ6GBbC@nathan>
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