[Pixman] [ssse3]Optimization for fetch_scanline_x8r8g8b8

Siarhei Siamashka siarhei.siamashka at gmail.com
Fri Aug 27 07:57:12 PDT 2010

On Friday 27 August 2010 15:00:49 Xu, Samuel wrote:
> Hi, Siarhei Siamashka:
> 	Thanks for quick response!
> 	For 64 bit detect_cpu_features(), if ignore HAVE_GETISAX and _MSC_VER,
> 	it is ok for us to simplify it as your example in next update.

If you can ensure MSVC compatibility and make it work with your optimizations, 
then it would be really great. But if it is totally untested, I don't feel
comfortable about having it just blindly replicated from 32 to 64 bits with the 
hope that it will work.

It's just my opinion, the others may disagree. And the others may also try to
test your patch on win32 or solaris systems, providing a lot more useful
feedback than me.

> For pixman-ssse3.c, maybe we have 2 options:
>  1) duplicate 6562 lines from pixman-sse2.c to new pixman-
>     ssse3.c in 1st patch (of course to replace 2 entries with newly added
>     SSSE3 asm optimization), and then add "merge" mechanism in later patch.

No, there is no need to duplicate anything.

>  2) firstly add "merge" mechanism patch, and the added new pixman-ssse3.c in
>     later patch, which might be shorter (111 lines) Does it mean 
>     1) option is preferred?

What problems do you have without "merge" mechanism? The pixman-sse2.c works
fine without it, and it does properly fallback to MMX code if SSE2 does not
support some operations. Similarly, SSSE3 can fallback to SSE2 in the very same 

Best regards,
Siarhei Siamashka
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