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From: Eli Zaretskii <eliz@gnu.org>
To: Helmut Eller <eller.helmut@gmail.com>
Cc: gerd.moellmann@gmail.com, emacs-devel@gnu.org
Subject: Re: MPS prstack
Date: Mon, 27 May 2024 14:34:31 +0300	[thread overview]
Message-ID: <86v82zv67s.fsf@gnu.org> (raw)
In-Reply-To: <87le3vogt8.fsf@gmail.com> (message from Helmut Eller on Mon, 27 May 2024 09:27:31 +0200)

> From: Helmut Eller <eller.helmut@gmail.com>
> Cc: Eli Zaretskii <eliz@gnu.org>,  Emacs Devel <emacs-devel@gnu.org>
> Date: Mon, 27 May 2024 09:27:31 +0200
> 
> Somewhat related: I wonder if this line in print_stack_push is safe:
> 
>   prstack.stack[prstack.sp++] = e;
> 
> This is not an atomic operation and prstack.sp gets updated before the
> new stack slot is initialized.

Are you sure?  I think the above assigns e to
prstack.stack[prstack.sp], and then increments prstack.sp.  What you
describe is this instead:

  prstack.stack[++prstack.sp] = e;

By analogy with the original code above, what does the following do?

  char *s;
  *s++ = 'a';

AFAIU, it stores 'a' in the address pointed by s and then increments
s.



      parent reply	other threads:[~2024-05-27 11:34 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-05-20 17:54 MPS prstack Helmut Eller
2024-05-20 18:21 ` Gerd Möllmann
2024-05-20 18:32   ` Helmut Eller
2024-05-21  3:30     ` Gerd Möllmann
2024-05-22 16:27 ` Helmut Eller
2024-05-22 17:55   ` Gerd Möllmann
2024-05-24 14:17   ` Helmut Eller
2024-05-24 14:27     ` Gerd Möllmann
2024-05-25 13:45       ` Gerd Möllmann
2024-05-27  7:27         ` Helmut Eller
2024-05-27  8:43           ` Gerd Möllmann
2024-05-27  9:15             ` Helmut Eller
2024-05-27  9:47               ` Gerd Möllmann
2024-05-27 11:45               ` Eli Zaretskii
2024-05-27 12:39                 ` Helmut Eller
2024-05-27 13:12                   ` Eli Zaretskii
2024-05-27 14:15                     ` Helmut Eller
2024-05-27 14:37                       ` Mattias Engdegård
2024-05-27 14:54                         ` Helmut Eller
2024-05-27 14:43                       ` Po Lu
2024-05-27 15:08                         ` Helmut Eller
2024-05-27 11:34           ` Eli Zaretskii [this message]

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