[Bug target/90606] Replace mfence with faster xchg for std::memory_order_seq_cst.

[ubizjak at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90606

Uroš Bizjak <ubizjak at gmail dot com> changed:

           What    |Removed                     |Added
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             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |DUPLICATE

--- Comment #2 from Uroš Bizjak <ubizjak at gmail dot com> ---
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*** This bug has been marked as a duplicate of bug 91719 ***