Infrequently, but, for example, handling glyph strings, we require the
string to be nul terminated. (Otherwise an error occurs, which was
previously compounded by a drastic leak.)
Handling clip as part of the surface state, as opposed to being part of
the operation state, is cumbersome and a hindrance to providing true proxy
surface support. For example, the clip must be copied from the surface
onto the fallback image, but this was forgotten causing undue hassle in
each backend. Another example is the contortion the meta surface
endures to ensure the clip is correctly recorded. By contrast passing the
clip along with the operation is quite simple and enables us to write
generic handlers for providing surface wrappers. (And in the future, we
should be able to write more esoteric wrappers, e.g. automatic 2x FSAA,
trivially.)
In brief, instead of the surface automatically applying the clip before
calling the backend, the backend can call into a generic helper to apply
clipping. For raster surfaces, clip regions are handled automatically as
part of the composite interface. For vector surfaces, a clip helper is
introduced to replay and callback into an intersect_clip_path() function
as necessary.
Whilst this is not primarily a performance related change (the change
should just move the computation of the clip from the moment it is applied
by the user to the moment it is required by the backend), it is important
to track any potential regression:
ppc:
Speedups
========
image-rgba evolution-20090607-0 1026085.22 0.18% -> 672972.07 0.77%: 1.52x speedup
▌
image-rgba evolution-20090618-0 680579.98 0.12% -> 573237.66 0.16%: 1.19x speedup
▎
image-rgba swfdec-fill-rate-4xaa-0 460296.92 0.36% -> 407464.63 0.42%: 1.13x speedup
▏
image-rgba swfdec-fill-rate-2xaa-0 128431.95 0.47% -> 115051.86 0.42%: 1.12x speedup
▏
Slowdowns
=========
image-rgba firefox-periodic-table-0 56837.61 0.78% -> 66055.17 3.20%: 1.09x slowdown
▏
Hook into the scanner to write out binary version of the tokenized
objects -- note we bind executable names (i.e. check to see if is an
operator and substitute the name with an operator -- this breaks
overloading of operators by scripts).
By converting scripts to a binary form, they are more compact and
execute faster:
firefox-world-map.trace 526850146 bytes
bound.trace 275187755 bytes
[ # ] backend test min(s) median(s) stddev. count
[ 0] null bound 34.481 34.741 0.68% 3/3
[ 1] null firefox-world-map 89.635 89.716 0.19% 3/3
[ 0] drm bound 79.304 79.350 0.61% 3/3
[ 1] drm firefox-world-map 135.380 135.475 0.58% 3/3
[ 0] image bound 95.819 96.258 2.85% 3/3
[ 1] image firefox-world-map 156.889 156.935 1.36% 3/3
[ 0] xlib bound 539.130 550.220 1.40% 3/3
[ 1] xlib firefox-world-map 596.244 613.487 1.74% 3/3
This trace has a lot of complex paths and the use of binary floating point
reduces the file size by about 50%, with a commensurate reduction in scan
time and significant reduction in operator lookup overhead. Note that this
test is still IO/CPU bound on my i915 with its pitifully slow flash...
Add a CairoScript interpreter library and use it to replay the test output
for the CairoScript backend. The library is also used by the currently
standalone Sphinx debugger [git://anongit.freedesktop.org/~ickle/sphinx].
The syntax/operator semantics are not yet finalized, but are expected to
mature before the next stable release.
