linux-kernel - Re: [PATCH] riscv/atomic: Do proper sign extension also for unsigned in arch

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Message-ID: <mvmo6zj2zcg.fsf@suse.de>
Date: Mon, 03 Feb 2025 09:42:55 +0100
From: Andreas Schwab <schwab@...e.de>
To: Jessica Clarke <jrtc27@...c27.com>
Cc: Alexandre Ghiti <alex@...ti.fr>,  linux-riscv@...ts.infradead.org,
  linux-kernel@...r.kernel.org
Subject: Re: [PATCH] riscv/atomic: Do proper sign extension also for
 unsigned in arch_cmpxchg

On Jan 30 2025, Jessica Clarke wrote:

> On 30 Jan 2025, at 15:53, Andreas Schwab <schwab@...e.de> wrote:
>> 
>> On Jan 30 2025, Alexandre Ghiti wrote:
>> 
>>> a2 is used as it is passed by the calling function, so we can't be sure a2
>>> is sign extended to me, what am I missing?
>> 
>> 32-bit scalar arguments are guaranteed to be sign extended on entry.
>
> Firstly, the calling convention is irrelevant if the function is
> inlined, which this almost always will be.

This is only about the non-inlined variant.

-- 
Andreas Schwab, SUSE Labs, schwab@...e.de
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