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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/106776] Unexpected use-after-free warning
Date: Sat, 22 Oct 2022 01:27:34 +0000	[thread overview]
Message-ID: <bug-106776-4-vQlQtuPjbq@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-106776-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106776

--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Leandro Nini from comment #2)
> Oh, now I see it, it wasn't that obvious in the first test. But why is the
> compiler allowed to postpone the store after deleting the pointer? Is there
> some undefined behavior involved here or what?

So the branch where the read after delete happens just happens to be dead code
but GCC cannot prove it statically due to what I mentioned in comment #4.

Oh if you compile the testcase in comment #4 with -fno-exceptions you don't get
the warning. Or marking f as noexcept. I have not looked into what could be
done for either other testcase though.

  parent reply	other threads:[~2022-10-22  1:27 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-08-30  9:12 [Bug middle-end/106776] New: " drfiemost at email dot it
2022-08-30 16:34 ` [Bug middle-end/106776] " msebor at gcc dot gnu.org
2022-09-28 14:33 ` drfiemost at email dot it
2022-10-22  1:08 ` pinskia at gcc dot gnu.org
2022-10-22  1:24 ` pinskia at gcc dot gnu.org
2022-10-22  1:27 ` pinskia at gcc dot gnu.org [this message]
2023-05-30 17:03 ` drfiemost at yahoo dot com

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