linux-kernel - Re: [PATCH 00/17] Introduce and use generic parity32/64 helper

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Message-ID: <1cebfebb9c205a1ebc5722ca7e3b87339ceb3c79.camel@ozlabs.org>
Date: Mon, 24 Feb 2025 15:58:49 +0800
From: Jeremy Kerr <jk@...abs.org>
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 Yu-Chun Lin <eleanor15x@...il.com>
Subject: Re: [PATCH 00/17] Introduce and use generic parity32/64 helper

Hi Kuan-Wei,

> Several parts of the kernel contain redundant implementations of parity
> calculations for 32-bit and 64-bit values. Introduces generic
> parity32() and parity64() helpers in bitops.h, providing a standardized
> and optimized implementation.  

More so than __builtin_parity() ?

I'm all for reducing the duplication, but the compiler may well have a
better parity approach than the xor-folding implementation here. Looks
like we can get this to two instructions on powerpc64, for example.

Cheers,


Jeremy