linux-kernel - Re: [PATCH 6/6] [RESEND] drm/amdgpu: work around llvm bug #42576

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Date:   Wed, 2 Oct 2019 10:07:33 -0700
From:   Nathan Chancellor <natechancellor@...il.com>
To:     Nick Desaulniers <ndesaulniers@...gle.com>
Cc:     arnd@...db.de, David1.Zhou@....com, Hawking.Zhang@....com,
        airlied@...ux.ie, alexander.deucher@....com,
        amd-gfx@...ts.freedesktop.org, christian.koenig@....com,
        clang-built-linux@...glegroups.com, daniel@...ll.ch,
        dri-devel@...ts.freedesktop.org, le.ma@....com,
        linux-kernel@...r.kernel.org, ray.huang@....com
Subject: Re: [PATCH 6/6] [RESEND] drm/amdgpu: work around llvm bug #42576

On Wed, Oct 02, 2019 at 09:51:37AM -0700, 'Nick Desaulniers' via Clang Built Linux wrote:
> > Apparently this bug is still present in both the released clang-9
> > and the current development version of clang-10.
> > I was hoping we would not need a workaround in clang-9+, but
> > it seems that we do.
> 
> I think I'd rather:
> 1. mark AMDGPU BROKEN if CC_IS_CLANG. There are numerous other issues building
>    a working driver here.

The only reason I am not thrilled about this is we will lose out on
warning coverage while the compiler bug gets fixed. I think the AMDGPU
drivers have been the single biggest source of clang warnings.

I think something like:

depends on CC_IS_GCC || (CC_IS_CLANG && COMPILE_TEST)

would end up avoiding the runtime issues and give us warning coverage.
The only issue is that we would still need this patch...

Cheers,
Nathan