Mike Williams wrote:
> Never leave a developer in possession of a profiler ...
>
> So with my setup, nerdtree takes a while to start in large directory of
> files, such as VIM's src directory. On Windows the profiler shows a
> large amount of time is being spent in the CRT's isalnum(), isalpha()
> and islower() internals, coping with locale handling.
>
> Working backwards shows the calls are actually from the ASCII_IS...()
> macros in macros.h and mainly coming from get_name_len(),
> has_loop_cmd(), find_command(), etc - so from VIML processing. There is
> also a call in modifier_len() that AFAICT only has to handle ASCII as well.
>
> Since these macros enforce ASCII character range there is no need to hit
> locale handling. The simplest solution is to use a lookup table with a
> bit mask for the classifications needed. I have thrown in handling for
> VIM_ISDIGIT as well.
>
> After the patch, starting nerdtree in VIM's src is ~35% faster (1.7s vs
> 2.6s) and the CRT's locale handling functions no longer appear in the
> profile (and I warmed the file cache to remove disk reading from the
> times). In general this should help speed up longer running VIML scripts.
Yeah, we've had problems with library functions before.
I think using a table is often slower than simple compares, because a
table lookup has to access memory, while a compare is local inside the
CPU. Especially for ASCII_ISLOWER and ASCII_ISUPPER, it's just two
compares. Changing VIM_ISDIGIT() this way is likely to make it slower.
ASCII_ISALNUM() requires six compares, perhaps a table is faster then?
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/// Bram Moolenaar -- [email protected] -- http://www.Moolenaar.net \\\
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