Now that we have get_h_advances() and get_nominal_glyphs() implemented, the
overhead of doing a proper atomic load would be once per run, NOT once per
glyph. So, no need to pre-load the tables to avoid that overhead.
As such, hb_ot_font_set_funcs() has become really cheap. Can *finally* make
it be default font functions on all newly created fonts!
Some more measurable speedup. The recent commits' speedups are as follows:
Testing with Roboto, ****when disabling kern and liga****:
Before:
FT --features=-kern,-liga
user↦ 0m0.521s
OT --features=-liga,-kern
user↦ 0m0.568s
After:
FT --features=-liga,-kern
user↦ 0m0.428s
OT --features=-liga,-kern
user↦ 0m0.470s
So, 17% speedup.
Note that FT callbacks are faster than OT these days since we added an advance
cache to FT. I don't think the difference is enough to justify adding a cache
to OT.
When not disabling kern, the thing is three times slower, so the speedups
are three times less impressive... Still, 5% not bad for a codebase that I
otherwise thought is optimized out.
Note that, because of this and other optimiztions in our main shaper,
disabling kern and liga, the OT shaper is now *faster* than the fallback
shaper. So, that's my recommendation to clients that need the absolute
fastest...
How come this one is not generated by clang everything bot?!
../../../test/api/test-multithread.c:37:26: warning: initialization discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]
static char *font_path = "fonts/Inconsolata-Regular.abc.ttf";
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../../../test/api/test-multithread.c:38:21: warning: initialization discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]
Unused as of now. To be wired up to normalizer, which would remove
overhead and allow hb-ot-font initialization to become a no-op, so
we can enable it by default.
Instead of passing a CFLAG/CXXFLAG to define HB_EXTERN, define it
directly in src/hb.hh as __declspec(dllexport) extern when we are
building HarfBuzz as DLLs on Visual Studio. Define HB_INTERNAL
as nothing without defining HB_NO_VISIBILITY when building HarfBuzz as
DLLs to avoid linker errors on Visual Studio builds.
Also "install" harfbuzz-subset.dll into $(PREFIX)\bin as the
hb-subset utility will depend on that DLL at runtime, when HarfBuzz is
built as DLLs. Since it consists of private APIs that are subject to
change, we do not install its headers nor .lib file.
"The values in the right class table are stored pre-multiplied by the
number of bytes in a single kerning value, and the values in the left
class table are stored pre-multiplied by the number of bytes in one
row. This eliminates needing to multiply the row and column values
together to determine the location of the kerning value. The array can
be indexed by doing the right- and left-hand class mappings, adding the
class values to the address of the array, and fetching the kerning
value to which the new address points."
Behdad Esfahbod
Chun-wei Fan