linux-kernel - Re: [PATCH] signal: fix building with clang

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Date:   Thu, 7 Mar 2019 22:45:27 +0100
From:   Arnd Bergmann <arnd@...db.de>
To:     Oleg Nesterov <oleg@...hat.com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        "Eric W . Biederman" <ebiederm@...ssion.com>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        linux-arch <linux-arch@...r.kernel.org>,
        Ralf Baechle <ralf@...ux-mips.org>,
        Paul Burton <paul.burton@...s.com>,
        James Hogan <jhogan@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Deepa Dinamani <deepa.kernel@...il.com>,
        Christian Brauner <christian@...uner.io>,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>,
        linux-mips@...r.kernel.org
Subject: Re: [PATCH] signal: fix building with clang

On Thu, Mar 7, 2019 at 5:46 PM Oleg Nesterov <oleg@...hat.com> wrote:
>
> On 03/07, Arnd Bergmann wrote:
> >
> > We could use % everywhere,
>
> Yes.
>
> But again, why not simply use the "for (;;)" loops? Why we can't kill the
> supid switch(_NSIG_WORDS) tricks altogether?

I'd have to try, but I think you are right. It was probably an
overoptimization back in 1997 when the code got added to
linux-2.1.68pre1, and compilers have become smarter in the
meantime ;-)

Also, the common case these days is _NSIG_WORDS==1, which
is true on all 64-bit architectures other than MIPS64.

      Arnd