From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eli Zaretskii <eliz@gnu.org>
Subject: =?UTF-8?B?YnVnIzIzOTE3OiBQbGVhc2UgY29uc2lkZXIgbWFraW5nIEJ1ZyAj?=
 =?UTF-8?B?MjM5MTcgYSBibG9ja2VyIGZvciAyNS4xICh3YXMgUmU6IG9yZy1jYXB0dXJl?=
 =?UTF-8?B?OiBDYXB0dXJlIHRlbXBsYXRlIOKAmGfigJk6IE1hdGNoIGRhdGEgY2xvYmJl?=
 =?UTF-8?B?cmVkIGJ5IGJ1ZmZlciBtb2RpZmljYXRpb24gaG9va3Mp?=
Date: Wed, 20 Jul 2016 17:55:11 +0300
Message-ID: <83shv4z7e8.fsf__3306.31501642547$1469026634$gmane$org@gnu.org>
References: <87vb066ejv.fsf@linaro.org> <8360s67qcp.fsf@gnu.org>
	<87bn1yyaui.fsf@linaro.org>
	<CAM-tV-9Befm+jtvvO9tZsYwCbzgggumNgWeuPzV-i=ZB0mgPog@mail.gmail.com>
	<87mvlhmv0x.fsf_-_@moondust.awandering> <837fcl5zs9.fsf@gnu.org>
	<m28tx1o6h6.fsf@newartisans.com> <87a8hgkwcb.fsf@linaro.org>
	<8360s42mcb.fsf@gnu.org> <87eg6rgmlg.fsf@gmail.com>
	<83lh0y24y6.fsf@gnu.org> <jwvmvle5udz.fsf-monnier+emacsbugs@gnu.org>
	<83eg6q1hbo.fsf@gnu.org> <jwv1t2q5jsz.fsf-monnier+emacsbugs@gnu.org>
	<83a8hd1vzi.fsf@gnu.org> <jwvzipdeibv.fsf-monnier+emacsbugs@gnu.org>
	<834m7l1u8u.fsf@gnu.org> <jwvd1m9dran.fsf-monnier+emacsbugs@gnu.org>
Reply-To: Eli Zaretskii <eliz@gnu.org>
Mime-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 8bit
Return-path: <emacs-orgmode-bounces+geo-emacs-orgmode=m.gmane.org@gnu.org>
Received: from eggs.gnu.org ([2001:4830:134:3::10]:33307)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <Debian-debbugs@debbugs.gnu.org>) id 1bPsuu-000599-1G
	for emacs-orgmode@gnu.org; Wed, 20 Jul 2016 10:56:08 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <Debian-debbugs@debbugs.gnu.org>) id 1bPsut-0008VT-4l
	for emacs-orgmode@gnu.org; Wed, 20 Jul 2016 10:56:08 -0400
Sender: "Debbugs-submit" <debbugs-submit-bounces@debbugs.gnu.org>
Resent-Message-ID: <handler.23917.B23917.14690265427198@debbugs.gnu.org>
In-reply-to: <jwvd1m9dran.fsf-monnier+emacsbugs@gnu.org> (message from Stefan
	Monnier on Tue, 19 Jul 2016 21:50:07 -0400)
List-Id: "General discussions about Org-mode." <emacs-orgmode.gnu.org>
List-Unsubscribe: <https://lists.gnu.org/mailman/options/emacs-orgmode>,
	<mailto:emacs-orgmode-request@gnu.org?subject=unsubscribe>
List-Archive: <http://lists.gnu.org/archive/html/emacs-orgmode/>
List-Post: <mailto:emacs-orgmode@gnu.org>
List-Help: <mailto:emacs-orgmode-request@gnu.org?subject=help>
List-Subscribe: <https://lists.gnu.org/mailman/listinfo/emacs-orgmode>,
	<mailto:emacs-orgmode-request@gnu.org?subject=subscribe>
Errors-To: emacs-orgmode-bounces+geo-emacs-orgmode=m.gmane.org@gnu.org
Sender: "Emacs-orgmode"
	<emacs-orgmode-bounces+geo-emacs-orgmode=m.gmane.org@gnu.org>
To: Stefan Monnier <monnier@iro.umontreal.ca>
Cc: nljlistbox2@gmail.com, npostavs@users.sourceforge.net, jwiegley@gmail.com, rpluim@gmail.com, 23917@debbugs.gnu.org, alex.bennee@linaro.org

> From: Stefan Monnier <monnier@iro.umontreal.ca>
> Cc: rpluim@gmail.com,  23917@debbugs.gnu.org,  alex.bennee@linaro.org,  jwiegley@gmail.com,  nljlistbox2@gmail.com
> Date: Tue, 19 Jul 2016 21:50:07 -0400
> 
> > Do we care that using save-match-data in every call to replace-match
> > might mean a performance hit?
> 
> I do but:
> - to be honest, it's probably lost in the noise.
> - if we copy search_regs.start and search_regs.end with something like
>   alloca+memcpy (instead of calling Fmatch_data), the cost should be even more
>   lost in the noise.  Especially if you consider that the current code
>   already loops through the match-data to adjust it.
> - it's the best fix we've found so far.

What about Noam's suggestion:

> Is it not possible to adjust the match data *before* calling buffer
> modification hooks?  Seems to me the root of the problem is that buffer
> modification hooks get to see this invalid intermediate state where the
> match data is out of sync with the buffer.

Is it OK to adjust the match data before actually making the
replacement?  If so, I think it's a simpler solution.

> PS: I can think of one (theoretical) other/better way to fix this
>     problem: move the match-data adjustment so it's done within
>     replace_range before running the after-change-functions.

Isn't that almost the same as what Noam suggested?