[Pixman] [PATCH 0/5] Normal repeat mode support for nearest/bilinear scaling fast paths

[Taekyun Kim]

Hi all,

Recently I've profiled several applications using pixman.
(Webkit cairo port is my major concern)
Most of cases are covered by C, SSE2 and NEON fast paths now.
However siarhei's slow-path-reporter still reports some non-optimized
general_composite_rect().
One of them is PIXMAN_REPEAT_NORMAL.
This repeat mode is used for drawing tiled background or some gradient
patterns.

I've modified nearest/bilinear fast path macro templates to support NORMAL
repeat.
The basic idea is breaking down one scanline composition into several
NONE_REPEAT scanline compositions.
So we can use already implemented scanline functions.
This approach does not increase binary size much and gives us reasonable
speed up.

When width of src image is very small, too frequent function call can
decrease performance.
In this case, pre-repeating src scanline into temporary buffer can reduce
the function calls.
Bilinear may require last and first pixels to interpolate.
Temporary wrap-around buffer can resolve this case.

I want to know whether this approach is proper way to go.
Maybe you guys are thinking of handling repeat mode inside scanline
functions??
(Some scanline functions take max_vx though it is not used yet).

Any kind of comments would be appreciated.


Here're some benchmark results of SSE2 and NEON fast paths.

<< SSE2 Fast Paths >>
OP=SRC Bilinear Scaling 8888_8888
sse2_src_8888_8888 for comparison : 122.40 MPix/s

width = 1 to 512
Before  : 28.21 MPix/s
After   : 74.27 MPix/s (37.18 MPix/s without pre-repeating)

width = 15 to 512
Before  : 24.73 MPix/s
After   : 92.72 MPix/s

width = 63 to 512
Before  : 24.88 MPix/s
After   : 114.11 MPix/s

<< NEON Fast Paths >>
OP=SRC Bilinear Scaling 8888_8888
neon_src_8888_8888 for comparison : 99.56 MPix/s

width = 1 to 512
Before  : 5.48 MPix/s
After   : 30.66 MPix/s (10.13 MPix/s without pre-repeating)

width = 15 to 512
Before  : 3.81 MPix/s
After   : 43.95 MPix/s

width = 63 to 512
Before  : 4.16 MPix/s
After   : 78.93 MPix/s

-- 
Best Regards,
Taekyun Kim
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