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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/114865] [13/14/15 Regression]
 std::atomic<X>::compare_exchange_strong seems to hang under GCC 13  for C++11
Date: Sat, 27 Apr 2024 00:42:35 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D114865

--- Comment #12 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Peter Dimov from comment #11)
> So, basically, C++14 and above initialize the padding of
>=20
> ```
>     std::atomic<state_type> state{{ 0, 0x2222 }};
> ```
>=20
> in `main` to zero, which masks the problem in `generate`. (The problem in
> `generate` still exists because the assembly is identical - it just doesn=
't
> trigger because the padding is zero. If we manually poke something nonzero
> into the padding, it would (ought to) still break.)

No there is no problem in generate for C++14+ because there is no way to get
the padding non-zero for that variable.

The problem is only with C++11's std::atomic ...
See PR 111077 and such.=