[Pixman] bilinear fast path

[Alexander Larsson]

On Tue, 2010-03-16 at 09:49 +0200, Siarhei Siamashka wrote:
> On Monday 15 March 2010, Alexander Larsson wrote:
> > On Mon, 2010-03-15 at 17:05 +0200, Siarhei Siamashka wrote:
> > > Really good performance improvements for bilinear scaling are
> going to
> > > come
> > > from SIMD optimizations. To make it happen, scaler core needs to
> be
> > > isolated
> > > into a small simple function with a minimal number of checks and
> > > branches.
> >
> >
> http://cgit.freedesktop.org/~alexl/pixman/commit/?h=fast-bilinear&id=a
> 79daa
> >8453560b4193b848e51b4942dcdcd74c8d
> >
> > The "/* Main columns: */" part there is probably a good start for
> that.
> 
> Yes, I know :)  Just a switch on different repeat cases needs to be
> eliminated
> and it should become quite easy to vectorize. Removal of this switch
> may also
> improve performance of generic C code a bit more.

Switch? The main (i.e. non-border) pixels have straight linear code:

http://cgit.freedesktop.org/~alexl/pixman/tree/pixman/pixman-fast-path.c?h=fast-bilinear#n1854

There is no switch (or other repeat handling) in there, because we're
using FAST_PATH_SAMPLES_COVERS_CLIP.

-- 
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 Alexander Larsson                                            Red Hat, Inc 
       alexl at redhat.com            alexander.larsson at gmail.com 
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