[Pixman] [PATCH 1/3] autoconf: add MMX EXT support check

Søren Sandmann sandmann at cs.au.dk
Sun Feb 19 13:59:14 PST 2012

Matt Turner <mattst88 at gmail.com> writes:

> The current runtime test checked that MMX extensions were available
> before executing code in pixman-mmx.c, even though no MMX extensions
> were used.
> The new --{enable,disable}-mmxext flag enables the use of MMX extensions
> in pixman-mmx.c. This allows us to use a few more efficient instructions
> added with 3DNow and SSE1 by default, and also allows the builder to
> disable these instructions and use pixman-mmx.c on a system without MMX
> extensions, something that wasn't possible before.

Are there any interesting chips without MMX extensions? Pentium MMX
definitely is not interesting. If there aren't, I'd rather just get rid
of the ifdefs and unconditionally require MMX-ext to be present.

> The SSE intrinsics header xmmintrin.h includes the MMX extensions we
> want to use, while the mm3dnow.h header does not. Instead of compiling
> with -msse (which would cause SSE instructions to be generated), we use
> a hack and just #define __SSE__ before including xmmintrin.h.

I like this hack, but looking at the code it doesn't look like you are
using it?


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