Jordan Rupprecht 6d33362daf [libcxx][atomic] Fix failure mapping in compare_exchange_{strong,weak}. ... https://eel.is/c++draft/atomics.types.operations#23 says: ... the value of failure is order except that a value of `memory_order::acq_rel` shall be replaced by the value `memory_order::acquire` and a value of `memory_order::release` shall be replaced by the value `memory_order::relaxed`. This failure mapping is only handled for `_LIBCPP_HAS_GCC_ATOMIC_IMP`. We are seeing bad code generation for `compare_exchange_strong(cmp, 1, std::memory_order_acq_rel)` when using libc++ in place of libstdc++: https://godbolt.org/z/v3onrrq4G. This was caught by tsan tests after D99434, `[TSAN] Honor failure memory orders in AtomicCAS`, but appears to be an issue in non-tsan code. Reviewed By: ldionne, dvyukov Differential Revision: https://reviews.llvm.org/D103846		2021-06-15 07:55:23 -07:00
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replace_failure_order.pass.cpp	…
replace_failure_order_codegen.sh.cpp	[libcxx][atomic] Fix failure mapping in compare_exchange_{strong,weak}.	2021-06-15 07:55:23 -07:00