linux-kernel - Re: [PATCH] __div64_32(): straighten up inline asm constraints

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Message-ID: <44638q0-o866-2o6o-qsp2-q1q528o7o5s9@syhkavp.arg>
Date:   Mon, 30 Nov 2020 15:27:20 -0500 (EST)
From:   Nicolas Pitre <nico@...xnic.net>
To:     Nick Desaulniers <ndesaulniers@...gle.com>
cc:     Ard Biesheuvel <ardb@...nel.org>, Antony Yu <swpenim@...il.com>,
        Russell King <linux@...linux.org.uk>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        clang-built-linux <clang-built-linux@...glegroups.com>,
        Nathan Chancellor <natechancellor@...il.com>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH] __div64_32(): straighten up inline asm constraints

On Mon, 30 Nov 2020, Nick Desaulniers wrote:

> On Mon, Nov 30, 2020 at 11:05 AM Nicolas Pitre <nico@...xnic.net> wrote:
> 
> > +       __rem = __n >> 32;
> >         *n = __res;
> >         return __rem;
> 
> The above 3 statement could be:
> 
> ```
> *n = __res;
> return __n >> 32;
> ```

They could. However the compiler doesn't care, and the extra line makes 
it more obvious that the reminder is the high part of __n. So, 
semantically the extra line has value.

Thanks for the review.


Nicolas