[Pixman] performance of bilinear_interpolation

Søren Sandmann sandmann at cs.au.dk
Fri Sep 13 10:56:54 PDT 2013

Maksim Lin <maks at manichord.com> writes:

> And even on devices such as the Nexus10 (and I've now seen this on the
> tegra based Nexus7) pixman_composite_src_8888_8888_asm_neon *is*
> called for some gfxContext:Fill operations, but not others, hence the
> slow performance on those devices.

It may depend on whether Firefox is displaying the page zoomed or not.

> This leads me to think that its only for some operations that the
> runtime check to see if accelerated functions are available is
> failing.
> Would anyone be knwo why this would be? or perhaps be able to poitn me
> to the code where these runtime checks happen to see if I can debug
> why the checks sometimes don't work?

The fast path is chosen by _pixman_implementation_lookup_composite()
which searches a set of tables exported in the various pixman-<arch>.c


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