[Pixman] Compute flags at validation time instea

[Siarhei Siamashka]

On Thursday 25 February 2010, Soeren Sandmann wrote:
> Hi,
>
> I intend to land the branch here:
>
>         http://cgit.freedesktop.org/~sandmann/pixman/log/?h=more-flags
>
> fairly soon. It contains various optimizations:
>
> - Do the flags and extended-format computation at validation time
>   instead of composite time
>
> - Eliminate _pixman_image_is_solid() and _is_opaque() in favor of two
>   new flags.
>
> - Turn the need_workaround boolean into another flags
>
> Most of it should be fairly straight-forward, but as always, reviews
> appreciated.

Looks good in general.

Except that the introduction of FAST_PATH_IS_OPAQUE flag may probably make
operators optimization a bit more tricky for PIXMAN_REPEAT_NONE case.

Also "Restructure the code to use switches instead of ifs" part probably may
have uncertain effect on performance. Optimization manuals say that ifs are
generally faster than switches when one of the cases has much higher
probability than the others.

-- 
Best regards,
Siarhei Siamashka