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From: "Mattias Engdegård" <mattias.engdegard@gmail.com>
To: Stefan Monnier <monnier@iro.umontreal.ca>
Cc: martin rudalics <rudalics@gmx.at>, Eli Zaretskii <eliz@gnu.org>,
	65726@debbugs.gnu.org
Subject: bug#65726: 29.1.50; Crash in regexp engine
Date: Sat, 9 Sep 2023 18:34:42 +0200	[thread overview]
Message-ID: <B82BE3A0-193C-4B8A-81DE-F90B721B7424@gmail.com> (raw)
In-Reply-To: <jwvpm2r8htj.fsf-monnier+emacs@gnu.org>

9 sep. 2023 kl. 17.55 skrev Stefan Monnier <monnier@iro.umontreal.ca>:

> My patch didn't include the assertion :-)

Oh, I thought you meant the eassert (p2 >= done); added at the start of mutually_exclusive_aux. Sorry about the confusion.
Anyway, disassembling the regexp makes it clear why:

Disassembly of regexp "\\`[^ ]+\\( [^ ]+\\)*\\'"

    0  begbuf
    1  charset-not [ ]
    8  on-failure-jump-smart to 21
   11  charset-not [ ]
   18  jump to 8
   21  on-failure-jump to 54
   24  start-memory group 1
   26  exact " "
   29  charset-not [ ]
   36  on-failure-jump-smart to 49
   39  charset-not [ ]
   46  jump to 36
   49  stop-memory group 1
   51  jump to 21
   54  endbuf
   55  succeed

which unless I'm mistaken we can condense to:

Disassembly of regexp "\\(?:ba*\\)*"

    0  on-failure-jump to 18
    3  exact "b"
    6  on-failure-jump-smart to 15
    9  exact "a"
   12  jump to 6
   15  jump to 0
   18  succeed

so yes, we may need to remember where we've been. (At this point someone will inevitably point out a helpful invariant that is obvious in hindsight. This is just my cunning attempt at making that happen.)






  reply	other threads:[~2023-09-09 16:34 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-09-04  7:46 bug#65726: 29.1.50; Crash in regexp engine martin rudalics
2023-09-04  8:44 ` Mattias Engdegård
2023-09-04 12:12   ` Eli Zaretskii
2023-09-04 13:18     ` Mattias Engdegård
2023-09-04 13:26       ` Mattias Engdegård
2023-09-04 13:28       ` Eli Zaretskii
2023-09-04 15:47         ` Mattias Engdegård
2023-09-05 12:23           ` Mattias Engdegård
2023-09-05 13:08             ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-09-05 13:50               ` Mattias Engdegård
2023-09-05 15:33                 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-09-06 12:03                   ` Mattias Engdegård
2023-09-09 15:55                     ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-09-09 16:34                       ` Mattias Engdegård [this message]
2023-09-14 14:41                         ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-09-15 20:03                           ` Mattias Engdegård
2023-09-15 22:20                             ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-09-16  3:45                           ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-09-16 10:49                             ` Mattias Engdegård
2023-09-16 15:48                               ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-09-18  2:14                                 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-09-18  3:59                                   ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-09-18 12:32                                     ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-09-21 17:23                                       ` Mattias Engdegård
2023-09-21 18:08                                         ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-09-23 11:56                                           ` Mattias Engdegård
2023-09-04 14:32 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-09-04 15:57   ` Eli Zaretskii
2023-09-04 17:12     ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-09-10  7:50       ` Stefan Kangas
2023-09-10  7:55         ` Eli Zaretskii
2023-09-10 23:09           ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-09-11 14:46             ` Stefan Kangas
2023-09-05  7:14   ` martin rudalics
2023-09-11  8:10 ` Mattias Engdegård
2023-09-11 13:41   ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors

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