[Bug target/91719] gcc compiles seq_cst store on x86-64 differently from clang/icc

[ubizjak at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91719

--- Comment #7 from Uroš Bizjak <ubizjak at gmail dot com> ---
Created attachment 46861
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=46861&action=edit
Proposed patch that introduces use_xchg_for_atomic_store

The patch introduces use_xchg_for_atomic_store and enables it for
(m_INTEL | m_CORE_ALL). We need some confirmation from Intel and AMD, what
targets should have this tune enabled.