Re: [PATCH] riscv/atomic: Do proper sign extension also for unsigned in arch_cmpxchg

From: Andreas Schwab <schwab@suse.de>
To: Jessica Clarke <jrtc27@jrtc27.com>
Cc: Alexandre Ghiti <alex@ghiti.fr>,
	 linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] riscv/atomic: Do proper sign extension also for unsigned in arch_cmpxchg
Date: Mon, 03 Feb 2025 09:42:55 +0100	[thread overview]
Message-ID: <mvmo6zj2zcg.fsf@suse.de> (raw)
In-Reply-To: <CC2D9220-F8DE-4CC8-ACAD-7B1A21E276FE@jrtc27.com> (Jessica Clarke's message of "Thu, 30 Jan 2025 17:21:28 +0000")

On Jan 30 2025, Jessica Clarke wrote:

> On 30 Jan 2025, at 15:53, Andreas Schwab <schwab@suse.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@suse.de
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