[vim/vim] f_has(): fast-path for features not in has_list[] (PR #19550)

[mattn]

When querying has() for things like patch-*, vim_starting, gui_running, etc., these were only checked after a linear scan through all ~198 entries in has_list[]. Since none of them exist in that table, the scan always came up empty before reaching the actual check.

This moves those runtime-checked features before the has_list[] scan so we skip the unnecessary work.

Called has() 1000000 times per item, averaged over 3 runs:

feature	master	fast-path	change
patch-9.1.0001	6.04s	4.84s	-19.8%
patch1	5.69s	4.08s	-28.3%
vim_starting	5.77s	4.66s	-19.3%
gui_running	5.82s	4.36s	-25.0%
clipboard_working	6.01s	4.45s	-25.9%
linux	3.99s	4.08s	no change
eval	4.37s	4.47s	no change
xterm_clipboard	6.06s	6.27s	no change
writebackup	5.74s	5.66s	no change
nonexistent	6.32s	6.06s	no change
total	55.80s	48.93s	-12.3%

Items that hit the fast-path are 20-28% faster. No regression for items looked up via has_list[].

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You can view, comment on, or merge this pull request online at:

  https://github.com/vim/vim/pull/19550

Commit Summary

• 06b84ef f_has(): fast-path for features not in has_list[]

File Changes

(1 file)

• M src/evalfunc.c (351)

Patch Links:

• https://github.com/vim/vim/pull/19550.patch
• https://github.com/vim/vim/pull/19550.diff

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[Christian Brabandt]

chrisbra left a comment (vim/vim#19550)

thanks

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[Christian Brabandt]

Closed #19550 via 327e0e3.

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