[Pixman] [PATCH 1/4] pixman-fast-path: Add over_n_8888 fast path (disabled)

Ben Avison bavison at riscosopen.org
Wed Aug 26 04:06:59 PDT 2015

On Wed, 26 Aug 2015 09:46:49 +0100, Pekka Paalanen <ppaalanen at gmail.com> wrote:
> It's clearly controversial to add C fast paths, because it affects all
> targets that don't have an asm fast path for the same, and we cannot
> tell by just review whether it is going to be for better or (much)
> worse.

Yes, it's always going to be a risk changing the cross-platform
functions. Few developers are going to be able to test all the supported
platforms, so we're always going to need help checking performance.
Should that be a reason not to even try C fast paths though?

It would be good to get some understanding of why VMX appears not to
benefit from any sort of over_n_8888 fast path, considering that so many
other platforms have added one. The information might be useful in
designing any future cross-platform code.

> Rpi should not be affected if we drop the C fast path patch,
> there is still the asm fast path patch. Right?

Yes, any ARM targets (ARMv6 or ARMv7) would use the ARMv6 implementation
in preference to the C one.


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