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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Sun, 27 Jan 2019 09:31:48 -0800
Message-ID: <CAHk-=wjBZvZ-AZ0OG+DBbyN_5CqPVNOva3v5vmUuSxvT+j1smg@mail.gmail.com>
Subject: Re: [PATCH 1/1] int_sqrt() adjustments
To:     Florian La Roche <florian.laroche@googlemail.com>
Cc:     Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
        Crt Mori <cmo@melexis.com>, Joe Perches <joe@perches.com>,
        Davidlohr Bueso <dave@stgolabs.net>,
        Will Deacon <will.deacon@arm.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Florian La Roche <Florian.LaRoche@gmail.com>
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On Sun, Jan 27, 2019 at 9:06 AM Florian La Roche
<florian.laroche@googlemail.com> wrote:
>
>
> -       m = 1UL << (__fls(x) & ~1UL);
> +       m = 1UL << ((int)__fls(x) & ~1);

No need to add the cast. It doesn't do anything and just makes the code uglier.

The type of a shift operator is the type of the left side of the shift
(with the usual int-promotion).

The type of the right side simply doesn't matter (the *value* does, of
course, but because the value range is limited, the cast is just
noise).

                Linus