linux-kernel - Re: [PATCH] ARM: mtd-xip: work around clang/llvm bug

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Message-ID: <20190709222517.c3nn6fgrz2eost3s@shell.armlinux.org.uk>
Date:   Tue, 9 Jul 2019 23:25:17 +0100
From:   Russell King - ARM Linux admin <linux@...linux.org.uk>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Nick Desaulniers <ndesaulniers@...gle.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        clang-built-linux <clang-built-linux@...glegroups.com>
Subject: Re: [PATCH] ARM: mtd-xip: work around clang/llvm bug

On Tue, Jul 09, 2019 at 08:40:51PM +0200, Arnd Bergmann wrote:
> On Tue, Jul 9, 2019 at 8:08 PM 'Nick Desaulniers' via Clang Built
> Linux <clang-built-linux@...glegroups.com> wrote:
> > On Tue, Jul 9, 2019 at 1:41 AM Linus Walleij <linus.walleij@...aro.org> wrote:
> >
> > > I guess this brings up the old question whether the compiler should
> > > be worked around or just considered immature, but as it happens this
> >
> > Definitely a balancing act; we prioritize work based on what's
> > feasible to work around vs must be implemented.  A lot of my time is
> > going into validation of asm goto right now, but others are ramping up
> > on the integrated assembler (clang itself can be invoked as a
> > substitute for GNU AS; but there's not enough support to do `make
> > AS=clang` for the kernel just yet).
> 
> Note that this bug is the same with both gas and AS=clang, which also
> indicates that clang implemented the undocumented .rep directive
> for compatibility.
> 
> Overall I think we are at the point where building the kernel with clang-8
> is mature enough that we should work around bugs like this where it is
> easy enough rather than waiting for clang-9.

While both assemblers seem to support both .rept and .rep, might it
be an idea to check what the clang-8 situation is with .rept ?

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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