GNU bug report logs - #56682
Fix the long lines font locking related slowdowns

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Message #1944 received at 56682 <at> debbugs.gnu.org (full text, mbox):

From: Dmitry Gutov <dgutov <at> yandex.ru>
To: Gregory Heytings <gregory <at> heytings.org>
Cc: 56682 <at> debbugs.gnu.org, Eli Zaretskii <eliz <at> gnu.org>,
 Stefan Monnier <monnier <at> iro.umontreal.ca>
Subject: Re: bug#56682: locked narrowing
Date: Wed, 30 Nov 2022 02:47:41 +0200

On 30/11/2022 02:15, Gregory Heytings wrote:
> 
>>> The result will be that the benchmark will report ~30ms both near BOB 
>>> and near EOB. So the long-lines-threshold thingy adds a regression here.
>>
>> It's not a regression, it's the price we agreed to pay to detect 
>> whether the buffer contains long lines.  That detection happens 
>> dynamically, to catch cases when long lines are inserted in a buffer.
>>
> 
> After looking at this closely, it turns out that the change in 
> 1c837c42c2 doesn't do what it was meant to do.  Sigh...  Dmitry, can you 
> confirm that the following change fixes this?
> 
> diff --git a/src/xdisp.c b/src/xdisp.c
> index b09aa6ec96..cdd6a7f5fe 100644
> --- a/src/xdisp.c
> +++ b/src/xdisp.c
> @@ -19535,7 +19535,7 @@ redisplay_window (Lisp_Object window, bool 
> just_this_one_p)
>     /* Check whether the buffer to be displayed contains long lines.  */
>     if (!NILP (Vlong_line_threshold)
>         && !current_buffer->long_line_optimizations_p
> -      && CHARS_MODIFF - CHARS_UNCHANGED_MODIFIED > 8)
> +      && CHARS_MODIFF - UNCHANGED_MODIFIED > 8)
>       {
>         ptrdiff_t cur, next, found, max = 0, threshold;
>         threshold = XFIXNUM (Vlong_line_threshold);
> 

Looking good. Thanks, Gregory!

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