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From: Paul Eggert <eggert@cs.ucla.edu>
To: Stefan Monnier <monnier@iro.umontreal.ca>
Cc: 41321@debbugs.gnu.org, Pip Cet <pipcet@gmail.com>
Subject: bug#41321: 27.0.91; Emacs aborts due to invalid pseudovector objects
Date: Fri, 29 May 2020 13:40:33 -0700	[thread overview]
Message-ID: <cc3030ac-1e6f-ca75-8e5f-20bd69967565@cs.ucla.edu> (raw)
In-Reply-To: <jwvzh9qcwyn.fsf-monnier+emacs@gnu.org>

On 5/29/20 1:26 PM, Stefan Monnier wrote:

> The original problematic case is for wide-int where a 64bit Lisp_Object
> containing a symbol is split into a 32bit tag saying "this is a symbol"
> and a 32bit pointer to which an offset has been added.
> 
> So when we encounter a 32bit word on the stack, it may be a "plain
> pointer" or it may be the 32bit of a pointer to a symbol with an
> offset applied but we can't tell which it is because we don't have the
> tag at that point.

Oh, you're right. Thanks, I was thinking only of the USE_LSB_TAG case.

For the !USE_LSB_TAG case, we should check whether the word is aligned for
'struct Lisp_Symbol', not whether it has the Lisp_Symbol tag, when deciding
quickly whether to add 'lispsym' and then do the second rbtree lookup. Something
like this:

  (USE_LSB_TAG
   ? (uintptr_t) word % GCALIGNMENT == Lisp_Symbol
   : (uintptr_t) word % alignof (struct Lisp_Symbol) == 0)

I'll fold this idea into the next iteration of the patch I'm working on.





  reply	other threads:[~2020-05-29 20:40 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 [this message]
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
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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