GNU bug report logs - #58558
29.0.50; re-search-forward is slow in some buffers

Previous Next

Full log

Message #212 received at 58558 <at> debbugs.gnu.org (full text, mbox):

From: Stefan Monnier <monnier <at> iro.umontreal.ca>
To: Ihor Radchenko <yantar92 <at> posteo.net>
Cc: 58558 <at> debbugs.gnu.org, Alan Mackenzie <acm <at> muc.de>,
 Eli Zaretskii <eliz <at> gnu.org>, larsi <at> gnus.org
Subject: Re: bug#58558: 29.0.50; re-search-forward is slow in some buffers
Date: Wed, 12 Apr 2023 11:20:17 -0400

> I confirm that it does fix the problem. But why not `with-temp-buffer'?

I think it's for compatibility with TECO Emacs or something like that :-)

> Also, how come `setq' changes the global variable value despite it is
> let-bound?

Because the `let` and the `setq` were not performed in the same buffer,
so if the var is buffer-local ...

> To improve the performance, the two obvious ways are reducing the number
> of SYNTAX_TABLE_BYTE_TO_CHAR calls in re_match_2_internal and speeding
> up buf_bytepos_to_charpos.

I think the behavior you experience doesn't require "speeding up" but it
requires "fixing a performance bug".  Technically it's the same, but still..

> I'd prefer the latter as it is used ubiquitously across Emacs and
> making point lookup faster will thus benefit other places as well.

Why choose?

For the former, we could probably extend the `b_property` and
`e_property` fields of `gl_state` (which hold charpos) to also store
their bytepos equivalent, which should significantly reduce the number
of conversions between bytepos and charpos.


        Stefan

Previous Next

GNU bug tracking system
Copyright (C) 1999 Darren O. Benham, 1997,2003 nCipher Corporation Ltd, 1994-97 Ian Jackson.