linux-kernel - Re: [PATCH v4 1/3] math.h: add DIV_ROUND_UP_NO

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Message-ID: <CAHk-=whrytmsiaLS=rn==qrYw81y2Qiv6dAZxvGzwgX=dMFxng@mail.gmail.com>
Date:   Wed, 25 Oct 2023 07:41:15 -1000
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     David Laight <David.Laight@...lab.com>
Cc:     Sebastian Reichel <sebastian.reichel@...labora.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        "linux-clk@...r.kernel.org" <linux-clk@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Niklas Schnelle <schnelle@...ux.ibm.com>,
        "kernel@...labora.com" <kernel@...labora.com>
Subject: Re: [PATCH v4 1/3] math.h: add DIV_ROUND_UP_NO_OVERFLOW

On Tue, 24 Oct 2023 at 22:38, David Laight <David.Laight@...lab.com> wrote:
>
> From: Linus Torvalds
> > >  - we can't even use a statement expression and __auto_type, because
> > > these things are used in type definitions etc and need to be constant
> > > expressions
>
> Doesn't min() get around that by using is_constexpr() and
> __builtin_choose_exptr() - the same could be done here.

Nope. I wanted to do it that way - it would have made things much
simpler and avoid the whole _Generic() thing, but try it - you cannot
use statement expressions in a non-function context even with
__builtin_choose_expr().

And no, min/max have never been usable in that context

                 Linus