From: David Laight <david.laight.linux@gmail.com>
To: Andreas Schwab <schwab@linux-m68k.org>
Cc: "Theodore Tso" <tytso@mit.edu>,
Guan-Chun Wu <409411716@gms.tku.edu.tw>,
Andreas Dilger <adilger.kernel@dilger.ca>,
linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org,
visitorckw@gmail.com
Subject: Re: [PATCH] ext4: improve str2hashbuf by processing 4-byte chunks
Date: Fri, 21 Nov 2025 11:59:31 +0000 [thread overview]
Message-ID: <20251121115931.411ab538@pumpkin> (raw)
In-Reply-To: <87a50flko1.fsf@igel.home>
On Fri, 21 Nov 2025 11:55:26 +0100
Andreas Schwab <schwab@linux-m68k.org> wrote:
> On Nov 20 2025, Theodore Tso wrote:
>
> > Secondly, it's not that a promotion happens before "any" arithmetic.
> > If we add two 8-bit values together, promotion doesn't happen.
>
> That is not true. Integer promotion is applied individually to each
> operand independent of context.
True.
You can think of the promotion happening every time a 'variable' is
read into a cpu register for any operation (including an assignment).
Similarly every write to a variable discards the high bits.
David
prev parent reply other threads:[~2025-11-21 11:59 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-11-16 13:01 [PATCH] ext4: improve str2hashbuf by processing 4-byte chunks Guan-Chun Wu
2025-11-16 19:35 ` David Laight
2025-11-17 14:20 ` Guan-Chun Wu
2025-11-20 15:58 ` Theodore Tso
2025-11-20 16:58 ` Kuan-Wei Chiu
2025-11-20 18:27 ` David Laight
2025-11-21 10:07 ` Geert Uytterhoeven
2025-11-21 10:55 ` Andreas Schwab
2025-11-21 11:59 ` David Laight [this message]
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