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

> 
> On Thu, 16 Apr 2020 16:00:29 -0700
> Paul Eggert <eggert@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.