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From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/107500] Useless atexit entry for ~constant_init in eh_globals.cc
Date: Thu, 03 Nov 2022 11:52:10 +0000	[thread overview]
Message-ID: <bug-107500-4-jx2XrtalGK@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-107500-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107500

--- Comment #17 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to R. Diez from comment #16)
> Therefore, variable "static __cxa_eh_globals eh_globals" in the past was
> already initialised before any users (probably because static memory being
> zeroed on start-up). The situation has not changed now.

Now it's enforced by the compiler and will fail to compile if for some reason
it can't be statically initialized.

> This static variable already outlived anything else, as there was no
> destructor changing anything on termination.

Semantically, no, that's wrong. The C++ standard still says its lifetime ends,
and the compiler can optimize based on that. It's storage is not reused, but
its lifetime does end.

But it also says the lifetime of the wrapper ends, so accessing eh_globals.obj
is still semantically undefined.

> Your patch introduced wrapper "struct constant_init" around it, which makes
> GCC generate a constructor for the wrapper solely to register an empty
> destructor with atexit(). Otherwise, the wrapper does nothing else useful.
> 
> Your patch also changes '__eh_globals_init::_M_init' (a different global
> object) to a static member. Is that not enough to fix the original problem?

Yes, probably.

  parent reply	other threads:[~2022-11-03 11:52 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-11-01 17:53 [Bug c++/107500] New: " rdiezmail-gcc at yahoo dot de
2022-11-02 12:07 ` [Bug libstdc++/107500] " redi at gcc dot gnu.org
2022-11-02 12:08 ` [Bug c++/107500] " redi at gcc dot gnu.org
2022-11-02 12:13 ` redi at gcc dot gnu.org
2022-11-02 12:46 ` rdiezmail-gcc at yahoo dot de
2022-11-02 13:01 ` rdiezmail-gcc at yahoo dot de
2022-11-02 13:04 ` redi at gcc dot gnu.org
2022-11-02 13:09 ` redi at gcc dot gnu.org
2022-11-02 13:29 ` rdiezmail-gcc at yahoo dot de
2022-11-02 13:36 ` rdiezmail-gcc at yahoo dot de
2022-11-02 14:17 ` redi at gcc dot gnu.org
2022-11-02 14:38 ` redi at gcc dot gnu.org
2022-11-02 15:47 ` pinskia at gcc dot gnu.org
2022-11-02 16:12 ` rdiezmail-gcc at yahoo dot de
2022-11-02 17:16 ` redi at gcc dot gnu.org
2022-11-02 17:46 ` redi at gcc dot gnu.org
2022-11-03  7:57 ` rdiezmail-gcc at yahoo dot de
2022-11-03 11:52 ` redi at gcc dot gnu.org [this message]
2022-11-03 11:55 ` redi at gcc dot gnu.org
2022-11-04  9:42 ` sebastian.huber@embedded-brains.de
2022-11-04 12:43 ` rdiezmail-gcc at yahoo dot de
2022-11-04 14:05 ` cvs-commit at gcc dot gnu.org
2022-11-04 14:15 ` redi at gcc dot gnu.org
2022-11-04 14:58 ` rdiezmail-gcc at yahoo dot de
2022-11-04 20:40 ` rdiezmail-gcc at yahoo dot de
2023-05-08 12:25 ` rguenth at gcc dot gnu.org
2024-03-16 10:25 ` redi at gcc dot gnu.org
2024-03-16 10:29 ` [Bug c++/107500] [12 Regression] " redi at gcc dot gnu.org
2024-03-18 14:03 ` cvs-commit at gcc dot gnu.org
2024-05-22 15:48 ` redi at gcc dot gnu.org

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