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Date:   Mon, 29 Jul 2019 13:47:55 -0700
From:   Nathan Chancellor <natechancellor@gmail.com>
To:     Nick Desaulniers <ndesaulniers@google.com>
Cc:     Michael Ellerman <mpe@ellerman.id.au>,
        Christophe Leroy <christophe.leroy@c-s.fr>,
        Segher Boessenkool <segher@kernel.crashing.org>,
        Arnd Bergmann <arnd@arndb.de>,
        kbuild test robot <lkp@intel.com>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        linuxppc-dev@lists.ozlabs.org, LKML <linux-kernel@vger.kernel.org>,
        clang-built-linux <clang-built-linux@googlegroups.com>
Subject: Re: [PATCH] powerpc: workaround clang codegen bug in dcbz
Message-ID: <20190729204755.GA118622@archlinux-threadripper>
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 <20190729203246.GA117371@archlinux-threadripper>
 <CAKwvOdm7GRBWYhPy4Ni2jbsXJp8gDF-AqaAxeLbZ03+LvHxADQ@mail.gmail.com>
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On Mon, Jul 29, 2019 at 01:45:35PM -0700, Nick Desaulniers wrote:
> On Mon, Jul 29, 2019 at 1:32 PM Nathan Chancellor
> <natechancellor@gmail.com> wrote:
> >
> > On Mon, Jul 29, 2019 at 01:25:41PM -0700, Nick Desaulniers wrote:
> > > But I'm not sure how the inlined code generated would be affected.
> >
> > For the record:
> >
> > https://godbolt.org/z/z57VU7
> >
> > This seems consistent with what Michael found so I don't think a revert
> > is entirely unreasonable.
> 
> Thanks for debugging/reporting/testing and the Godbolt link which
> clearly shows that the codegen for out of line versions is no
> different.  The case I can't comment on is what happens when those
> `static inline` functions get inlined (maybe the original patch
> improves those cases?).
> -- 
> Thanks,
> ~Nick Desaulniers

I'll try to build with various versions of GCC and compare the
disassembly of the one problematic location that I found and see
what it looks like.

Cheers,
Nathan