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From: "foom at fuhm dot net" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/95722] libatomic crashes on __atomic_load of const object
Date: Wed, 17 Jun 2020 19:10:37 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D95722

James Y Knight <foom at fuhm dot net> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |foom at fuhm dot net

--- Comment #1 from James Y Knight <foom at fuhm dot net> ---
The fix would be to have libatomic use a lock instead of the lock-free
cmpxchg16b instruction to implement atomic_load. But I think this is imposs=
ible
without causing incompatibility with older GCCs.

Older versions of GCC (before GCC 7), and Clang to this day, emitted cmpxch=
g16b
inline for a 16-byte atomic load when you compile with -mcx16.

And thus, unfortunately, I think if libatomic switched to a lock now, it wo=
uld
not be compatible with those older programs.=