[Intel-gfx] xf86-video-intel (git-13461a1): BROKEN with clang-3.2 due to __cpuid() not available?

[Chris Wilson]

On Tue, Feb 26, 2013 at 03:11:50PM +0100, Sedat Dilek wrote:
> On Tue, Feb 26, 2013 at 2:50 PM, Chris Wilson <chris at chris-wilson.co.uk> wrote:
> > On Tue, Feb 26, 2013 at 02:38:14PM +0100, Sedat Dilek wrote:
> >> On Tue, Feb 26, 2013 at 2:33 PM, Chris Wilson <chris at chris-wilson.co.uk> wrote:
> >> > On Tue, Feb 26, 2013 at 02:20:26PM +0100, Sedat Dilek wrote:
> >> >> On Tue, Feb 26, 2013 at 1:58 PM, Chris Wilson <chris at chris-wilson.co.uk> wrote:
> >> >> > On Tue, Feb 26, 2013 at 01:35:51PM +0100, Sedat Dilek wrote:
> >> >> >> With xf86-video-intel-git13461a1 [1] I see this:
> >> >> >>
> >> >> >> [ build-log ]
> >> >> >> ...
> >> >> >>   CC     sna_cpu.lo
> >> >> >> 8 warnings generated.
> >> >> >>   CC     sna_damage.lo
> >> >> >>   CC     sna_display.lo
> >> >> >> sna_cpu.c:47:2: error: implicit declaration of function '__cpuid' is
> >> >> >> invalid in C99 [-Werror,-Wimplicit-function-declaration]
> >> >> >>         __cpuid(1, eax, ebx, ecx, edx);
> >> >> >>         ^
> >> >> > [snip]
> >> >> >
> >> >> >> So, clang should be treated differently?
> >> >> >
> >> >> > It doesn't use cpuid.h unless the compiler claims to be gcc >= 4. It
> >> >> > would appear once again that clang is broken.
> >> >>
> >> >> Can you explain why clang is BROKEN in your eyes?
> >> >
> >> > Because it claims to be gcc 4, yet fails to provide a function/macro
> >> > provided by gcc 4.
> >>
> >> Even clang latest-git has same file [1].
> >> Any workaround you can imagine?
> >
> > && !defined(__clang__)
> >
> > Based on the bug reports I have, I would strongly recommend not to use
> > clang as it is known to miscompile the ddx. My outlook is jaundiced
> > though as people report the failures but not if it ever then succeeds in
> > not exploding during use.
> 
> Can you explain what you mean with "miscompilation"?

It generates invalid object code that cause segfaults during use.

Besides which as you have also demonstrated, it barely understands C.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre