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From: Dagfinn Ilmari Mannsåker <[email protected]>
To: Joel Jacobson <[email protected]>
Cc: pgsql-hackers <[email protected]>
Subject: Re: Optimize numeric multiplication for one and two base-NBASE digit multiplicands.
Date: Mon, 01 Jul 2024 13:25:08 +0100
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
References: <[email protected]>

"Joel Jacobson" <[email protected]> writes:

> Hello hackers,
>
> Attached patch introduces an optimization of mul_var() in numeric.c,
> targeting cases where the multiplicands consist of only one or two
> base-NBASE digits. Such small multiplicands can fit into an int64 and
> thus be computed directly, resulting in a significant performance
> improvement, between 26% - 34% benchmarked on Intel Core i9-14900K.
>
> This optimization is similar to commit d1b307eef2, that also targeted
> one and two base-NBASE digit operands, but optimized div_var().

div_var() also has an optimisation for 3- and 4-digit operands under
HAVE_INT128 (added in commit 0aa38db56bf), would that make sense in
mul_var() too?

> Regards,
> Joel

- ilmari

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