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From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/108374] [12/13 Regression] unexpected -Wstringop-overflow when using std::atomic and std::shared_ptr
Date: Thu, 12 Jan 2023 09:57:34 +0000	[thread overview]
Message-ID: <bug-108374-4-JLWhcX9nnn@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-108374-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108374

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Romain Geissler from comment #0)
>     std::weak_ptr<A> weakPointer(pointer);
> 
>     [[maybe_unused]] const unsigned int aAttr = weakPointer.lock()->_attr;

If pointer == nullptr then weakPointer.lock() is also null, and so
dereferencing it to access the attr member is undefined, and does indeed
perform an atomic load at address 0.

Instead of complaining about it, I would expect GCC to treat that undefined
condition as unreachable and optimize it away.

  parent reply	other threads:[~2023-01-12  9:57 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-11 18:18 [Bug tree-optimization/108374] New: " romain.geissler at amadeus dot com
2023-01-11 18:19 ` [Bug tree-optimization/108374] " romain.geissler at amadeus dot com
2023-01-12  9:43 ` rguenth at gcc dot gnu.org
2023-01-12  9:57 ` redi at gcc dot gnu.org [this message]
2023-01-12 10:00 ` rguenth at gcc dot gnu.org
2023-01-12 10:10 ` redi at gcc dot gnu.org
2023-01-12 11:34 ` jakub at gcc dot gnu.org
2023-05-08 12:26 ` [Bug tree-optimization/108374] [12/13/14 " rguenth at gcc dot gnu.org

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