GNU bug report logs - #40634
Massive pattern list handling with -E format seems very slow since 2.28.

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From: Norihiro Tanaka <noritnk <at> kcn.ne.jp>
To: <40634 <at> debbugs.gnu.org>
Cc: fryasu <at> yahoo.co.jp, Paul Eggert <eggert <at> cs.ucla.edu>, bug-gnulib <at> gnu.org
Subject: bug#40634: Massive pattern list handling with -E format seems very slow since 2.28.
Date: Fri, 17 Apr 2020 10:24:42 +0900

[Message part 1 (text/plain, inline)]

On Fri, 17 Apr 2020 09:35:36 +0900
Norihiro Tanaka <noritnk <at> kcn.ne.jp> wrote:

> 
> On Thu, 16 Apr 2020 16:00:29 -0700
> Paul Eggert <eggert <at> cs.ucla.edu> wrote:
> 
> > On 4/16/20 3:53 PM, Norihiro Tanaka wrote:
> > 
> > > I have had no idea to solve the problem yet.  If we revert it, bug#33357
> > > will come back.
> > 
> > Yes, I'd rather not revert if we can help it.
> > 
> > My own thought was to not analyze the regular expression if we discover that the input is empty. :-)
> 
> Now, I have a idea, it is that we build indexes of epsilon nodes
> including in follows before remove epsilon nodes.


I wrote fix for the bug, but it will be slower then at grep 2.27 yet.

[0001-dfa-build-auxiliary-indexes-before-remove-epsilon-cl.patch (text/plain, attachment)]

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