[Pixman] [PATCH] mmx: Use MMX2 intrinsics from xmmintrin.h directly.

[Matt Turner]

On Sun, Oct 25, 2015 at 1:13 PM, Matt Turner <mattst88 at gmail.com> wrote:
> On Sun, Oct 11, 2015 at 8:59 PM, Matt Turner <mattst88 at gmail.com> wrote:
>> We had lots of hacks to handle the inability to include xmmintrin.h
>> without compiling with -msse (lest SSE instructions be used in
>> pixman-mmx.c). Some recent version of gcc relaxed this restriction.
>>
>> Change configure.ac to test that xmmintrin.h can be included and that we
>> can use some intrinsics from it, and remove the work-around code from
>> pixman-mmx.c.
>>
>> Evidently allows gcc 4.9.3 to optimize better as well:
>>
>>    text    data     bss     dec     hex filename
>>  657078   30848     680  688606   a81de libpixman-1.so.0.33.3 before
>>  656710   30848     680  688238   a806e libpixman-1.so.0.33.3 after
>>
>> Signed-off-by: Matt Turner <mattst88 at gmail.com>
>> ---
>
> Ugh. This is apparently not sufficient...
>
> https://bugs.gentoo.org/show_bug.cgi?id=564024
>
> GCC allows you to *include* xmmintrin.h without enabling SSE, but it
> still doesn't allow you to use any of the functions:
>
> conftest.c: In function ‘main’:
> /usr/lib/gcc/x86_64-pc-linux-gnu/5.1.0/include/xmmintrin.h:1124:1:
> error: inlining failed in call to always_inline ‘_mm_mulhi_pu16’:
> target specific option mismatch
>  _mm_mulhi_pu16 (__m64 __A, __m64 __B)
>  ^
> conftest.c:12:7: error: called from here
>      w = _mm_mulhi_pu16(w, w);
>
> I'm not sure what to do except to revert.
>
> The MMX but no SSE case is important, at least it was in the past
> because of OLPC's XO-1.
>
> Suggestions besides reverting this?

I've now reverted this commit and committed Andrea's fix for clang.