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From: "rodgertq at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/88101] Implement P0528R3, C++20 cmpxchg and padding
 bits
Date: Tue, 15 Sep 2020 20:03:58 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D88101

--- Comment #4 from Thomas Rodgers <rodgertq at gcc dot gnu.org> ---
(In reply to andysem from comment #2)
> Another use case is C++20 atomic_ref, which may be bound to an object who=
se
> padding bits are in indeterminate state. An intrinsic to clear padding bi=
ts
> without altering the object value could be useful.

Having now implemented atomic<T>::wait for libstdc++, I think the intrinsic=
 to
clear padding bits before calling __builtin_memcmp for generic (trivially
copyable) T's is the right approach.=