[Pixman] xmmintrin.h (was [PATCH 2/4] Disable MMX when incompatible clang is being used.)

Matt Turner mattst88 at gmail.com
Tue Apr 10 12:30:12 PDT 2012

On Tue, Apr 10, 2012 at 1:50 AM, Jeremy Huddleston
<jeremyhu at freedesktop.org> wrote:
>>>>>> Newer clangs support the "K" constraint? Fixed in response to its use
>>>>>> in pixman? :)
>> And to close the loop on this, the fix has landed in clang trunk and will be in 3.1:
>> http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20120319/055254.html
> And the other half of the issue seems to be a bug in pixman (at least that's what I am told):
> """
>> FWIW the problem happening here with inlining is that at -O0 the constant isn't being propagated through the inlining and so we have the 'K' constant error that you see.
>  IMO, the source of this problem is that pixman isn't using clang's xmmintrin.h, which defines _mm_shuffle_pi16 for exactly this reason.  They should fix that.
> """

Sigh. The reason we're not just plainly using xmmintrin.h is that it
requires SSE. The MMX extension instructions we are using in
pixman-mmx.c are available in SSE and Extended 3DNow. If you compile
with -msse and include xmmintrin.h, you'll get lots of SSE
instructions that aren't in 3DNow.

Try the attached patch. It's how gcc's xmmintrin.h handles it.

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