GNU bug report logs - #35675
27.0.50; Is line-number-at-pos unnecessarily slow?

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From: Alex Branham <alex.branham <at> gmail.com>
To: 35675 <at> debbugs.gnu.org
Subject: bug#35675: 27.0.50; Is line-number-at-pos unnecessarily slow?
Date: Fri, 10 May 2019 15:55:09 -0500

Hi all -

I ran into a bottleneck at line-number-at-pos in ESS's indentation
engine. line-number-at-pos basically regex searches forward for \n's and
counts them up. This can be slow in a large buffer. It looks like
someone else has ran into this issue as well.[1]

With the advent of display-line-numbers-mode, I imagine there's a C
implementation of line-number-at-pos. I imagine the C implementation is
faster. Does it make sense for line-number-at-pos to just use the C
implementation?

Thanks,
Alex

Footnotes:
[1]  https://fuco1.github.io/2018-08-12-WAR-STORY:-When-turning-to-the-profiler-turns-out-to-be-a-good-call.html

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