From: Eli Zaretskii <eliz@gnu.org>
To: Pip Cet <pipcet@gmail.com>
Cc: eggert@cs.ucla.edu, 41321@debbugs.gnu.org, monnier@iro.umontreal.ca
Subject: bug#41321: 27.0.91; Emacs aborts due to invalid pseudovector objects
Date: Sat, 30 May 2020 14:31:02 +0300 [thread overview]
Message-ID: <831rn1mzgp.fsf@gnu.org> (raw)
In-Reply-To: <CAOqdjBfJ68Z-VvHufd=TwKn2+hKsCbZ31WOYM6Jdr3KVptWCHQ@mail.gmail.com> (message from Pip Cet on Sat, 30 May 2020 11:06:52 +0000)
> From: Pip Cet <pipcet@gmail.com>
> Date: Sat, 30 May 2020 11:06:52 +0000
> Cc: eggert@cs.ucla.edu, 41321@debbugs.gnu.org,
> Stefan Monnier <monnier@iro.umontreal.ca>
>
> > I understand that part, but my question was why, even before the
> > change in max_align_t, did we start requiring 8-byte alignment on
> > systems where that is not automatically guaranteed?
>
> I don't know. As I said, I think that was always buggy on pdumper
> systems, though the bug was very subtle. My guess is it predates
> pdumper, at which time it was a valid optimization.
How is pdumper involved here?
> > So this alignment requirement is only due to pthreads being used?
>
> I'm not sure what you're asking. Obviously there are systems on which
> unaligned accesses will fault or be very slow indeed, so we need to
> make sure, say, pure space allocations are aligned somehow. That
> requires a LISP_ALIGNMENT of 8. Everything beyond that is only for
> performance, pthreads, and SIMD types.
If the system guarantees 4-byte alignment from malloc (and/or a
similar alignment of the runtime C stack), then using that doesn't
trigger problems related to unaligned accesses, right? So let me
rephrase: why isn't 4-byte alignment "good enough" for us on systems
where malloc and the runtime stack are guaranteed to be thus aligned?
> > If
> > the two 32-bit parts of the object are non-contiguous, will we be able
> > to recognize such an object, and will we be able to mark it correctly,
> > and if so, how? IOW, don't we need the upper 32-bit (which encodes
> > the object type) for the purposes of marking it?
>
> For everything but symbols, we don't, mark_maybe_pointer called on the
> low 32 bits suffices. For symbols, mark_maybe_pointer needs to be
> changed to also check the pointer at <low 32-bit word> + &lispsym.
Right, that's what I thought. So this issue also has to be fixed on
emacs-27 in order for us to provide a stable Emacs 27.
next prev parent reply other threads:[~2020-05-30 11:31 UTC|newest]
Thread overview: 132+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-16 10:33 bug#41321: 27.0.91; Emacs aborts due to invalid pseudovector objects Eli Zaretskii
2020-05-16 16:33 ` Paul Eggert
2020-05-16 16:47 ` Eli Zaretskii
2020-05-17 10:56 ` Pip Cet
2020-05-17 15:28 ` Eli Zaretskii
2020-05-17 15:57 ` Eli Zaretskii
2020-05-22 7:22 ` Eli Zaretskii
2020-05-22 8:35 ` Andrea Corallo
2020-05-22 11:04 ` Eli Zaretskii
2020-05-22 12:55 ` Andrea Corallo
2020-05-22 10:54 ` Eli Zaretskii
2020-05-22 11:47 ` Pip Cet
2020-05-22 12:13 ` Eli Zaretskii
2020-05-22 12:39 ` Pip Cet
2020-05-22 12:48 ` Eli Zaretskii
2020-05-22 14:04 ` Pip Cet
2020-05-22 14:26 ` Eli Zaretskii
2020-05-22 14:40 ` Andrea Corallo
2020-05-22 19:03 ` Eli Zaretskii
[not found] ` <CAOqdjBdpU4U1NqErNH0idBmUxNeE3fL=2=KKpo9kbCM3DhW5gA@mail.gmail.com>
2020-05-23 17:58 ` Andrea Corallo
2020-05-23 22:37 ` Stefan Monnier
2020-05-23 22:41 ` Pip Cet
2020-05-23 23:26 ` Stefan Monnier
2020-05-22 12:32 ` Eli Zaretskii
2020-05-29 9:51 ` Eli Zaretskii
2020-05-29 10:00 ` Pip Cet
2020-05-23 23:54 ` Pip Cet
2020-05-24 14:24 ` Eli Zaretskii
2020-05-24 15:00 ` Pip Cet
2020-05-24 16:25 ` Eli Zaretskii
2020-05-24 16:55 ` Eli Zaretskii
2020-05-24 18:03 ` Pip Cet
2020-05-24 18:40 ` Eli Zaretskii
2020-05-24 19:40 ` Pip Cet
2020-05-25 2:30 ` Eli Zaretskii
2020-05-25 6:40 ` Pip Cet
2020-05-25 11:28 ` Pip Cet
2020-05-25 14:53 ` Eli Zaretskii
2020-05-25 15:12 ` Stefan Monnier
2020-05-26 3:39 ` Paul Eggert
2020-05-26 3:33 ` Paul Eggert
2020-05-26 6:18 ` Pip Cet
2020-05-26 7:51 ` Paul Eggert
2020-05-26 8:27 ` Pip Cet
2020-05-26 6:46 ` Paul Eggert
2020-05-26 15:17 ` Eli Zaretskii
2020-05-26 22:49 ` Paul Eggert
2020-05-27 15:26 ` Eli Zaretskii
2020-05-27 16:58 ` Paul Eggert
2020-05-27 17:33 ` Eli Zaretskii
2020-05-27 17:53 ` Paul Eggert
2020-05-27 18:24 ` Eli Zaretskii
2020-05-27 18:39 ` Paul Eggert
2020-05-28 2:43 ` Stefan Monnier
2020-05-28 7:27 ` Eli Zaretskii
2020-05-28 7:41 ` Paul Eggert
2020-05-28 13:30 ` Stefan Monnier
2020-05-28 14:28 ` Pip Cet
2020-05-28 16:24 ` Stefan Monnier
2020-05-29 9:43 ` Pip Cet
2020-05-29 18:31 ` Paul Eggert
2020-05-29 18:37 ` Pip Cet
2020-05-29 19:32 ` Paul Eggert
2020-05-29 19:37 ` Pip Cet
2020-05-29 20:26 ` Stefan Monnier
2020-05-29 20:40 ` Paul Eggert
2020-05-30 5:54 ` Eli Zaretskii
2020-05-30 17:52 ` Paul Eggert
2020-05-30 18:11 ` Eli Zaretskii
2020-05-30 18:17 ` Paul Eggert
2020-05-30 5:51 ` Eli Zaretskii
2020-05-30 14:26 ` Stefan Monnier
2020-05-27 17:57 ` Pip Cet
2020-05-27 18:39 ` Paul Eggert
2020-05-27 18:56 ` Pip Cet
2020-05-28 1:21 ` Paul Eggert
2020-05-28 6:31 ` Pip Cet
2020-05-28 7:47 ` Paul Eggert
2020-05-28 8:11 ` Pip Cet
2020-05-28 18:27 ` Eli Zaretskii
2020-05-28 19:33 ` Paul Eggert
2020-05-29 6:19 ` Eli Zaretskii
2020-05-29 20:24 ` Paul Eggert
2020-05-29 21:01 ` Pip Cet
2020-05-30 5:58 ` Eli Zaretskii
2020-05-30 7:19 ` Pip Cet
2020-05-30 9:08 ` Eli Zaretskii
2020-05-30 11:06 ` Pip Cet
2020-05-30 11:31 ` Eli Zaretskii [this message]
2020-05-30 13:29 ` Pip Cet
2020-05-30 16:32 ` Eli Zaretskii
2020-05-30 16:36 ` Pip Cet
2020-05-30 16:45 ` Eli Zaretskii
2020-05-30 18:04 ` Paul Eggert
2020-05-30 18:12 ` Pip Cet
2020-05-30 18:16 ` Eli Zaretskii
2020-05-30 18:45 ` Paul Eggert
2020-05-30 18:39 ` Pip Cet
2020-05-30 18:57 ` Paul Eggert
2020-05-30 19:06 ` Pip Cet
2020-05-30 21:27 ` Paul Eggert
2020-05-30 21:49 ` Pip Cet
2020-05-30 22:23 ` Paul Eggert
2020-05-30 22:54 ` Pip Cet
2020-05-30 16:31 ` Paul Eggert
2020-05-30 16:42 ` Eli Zaretskii
2020-05-30 17:06 ` Paul Eggert
2020-05-30 17:22 ` Eli Zaretskii
2020-05-30 18:12 ` Paul Eggert
2020-05-30 18:21 ` Eli Zaretskii
2020-05-30 19:14 ` Paul Eggert
2020-05-30 19:33 ` Eli Zaretskii
2020-05-30 22:18 ` Paul Eggert
2020-05-31 15:48 ` Eli Zaretskii
2020-06-01 14:48 ` Eli Zaretskii
2020-09-27 14:39 ` Lars Ingebrigtsen
2020-09-27 14:45 ` Pip Cet
2020-09-27 15:02 ` Lars Ingebrigtsen
2020-09-27 15:16 ` Eli Zaretskii
2020-05-30 16:53 ` Pip Cet
2020-05-30 5:50 ` Eli Zaretskii
2020-05-29 8:25 ` Pip Cet
2020-05-25 15:14 ` Eli Zaretskii
2020-05-25 17:41 ` Pip Cet
2020-05-24 19:00 ` Andy Moreton
2020-05-24 19:09 ` Pip Cet
2020-05-29 10:16 ` Eli Zaretskii
2020-05-29 10:34 ` Pip Cet
2020-05-29 10:55 ` Eli Zaretskii
2020-05-29 11:47 ` Pip Cet
2020-05-29 13:52 ` Eli Zaretskii
2020-05-29 14:19 ` Pip Cet
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