GNU bug report logs - #16232
[PATCH] grep: make --ignore-case (-i) faster (sometimes 10x) in multibyte locales

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Package: grep;

Reported by: Jim Meyering <jim <at> meyering.net>

Date: Mon, 23 Dec 2013 22:40:02 UTC

Severity: normal

Tags: patch

Done: Paul Eggert <eggert <at> cs.ucla.edu>

Bug is archived. No further changes may be made.

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From: Norihiro TANAKA <noritnk <at> kcn.ne.jp>
To: Jim Meyering <jim <at> meyering.net>
Cc: 16232 <16232 <at> debbugs.gnu.org>, Padraig Brady <P <at> draigbrady.com>
Subject: bug#16232: [PATCH] grep: make --ignore-case (-i) faster (sometimes 10x) in multibyte locales
Date: Thu, 20 Feb 2014 22:39:18 +0900

Hi Jim,

Your patch is probably right.

However, I think that the true cause for 100x slow is that DFA engine is
slower than regex engine for case-insensitive matching on a non-UTF-8
locle.

On a multibyte locale, for case-insensitive "a" grep prefers DFA engine,
but for character class "[Aa]" prefers regex engine.

Norihiro
This bug report was last modified 11 years and 82 days ago.

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