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From: "wuyongwei at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug target/80878] -mcx16 (enable 128 bit CAS) on x86_64 seems not
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Date: Tue, 16 Mar 2021 16:02:18 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D80878

--- Comment #29 from Yongwei Wu <wuyongwei at gmail dot com> ---
As usual, test results are always elusive. I have to add yet another import=
ant
piece of information. The very bad performance result does not occur on Lin=
ux,
but only on macOS (Homebrew versions of GCC and libatomic).

So far, it seems to indicate that this is more a libatomic issue on macOS,
which I traced to pthread_mutex_lock, instead of "lock cmpxchg16b" on Linux=
...=