Don't use atomic_thread_fence under TSAN #544
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TSAN is one of the best tools for checking correctness of concurrent programs out there, but sadly, it does not support atomic_thread_fence and unlikely ever will. But for good codegen on ARM we NEED atomic_thread_fence in shared_ptr. Hence, we need to selectively use it only when TSAN is disabled and fallback to an unconditional acq_rel operation where the ARM acquire fence will be performed even when we are not releaseing the last reference. This is pretty much equivalent semantically, but avoids false-positive TSAN reports.
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TSAN is one of the best tools for checking correctness of concurrent programs out there, but sadly, it does not support atomic_thread_fence and unlikely ever will.
But for good codegen on ARM we NEED atomic_thread_fence in shared_ptr. Hence, we need to selectively use it only when TSAN is disabled and fallback to an unconditional acq_rel operation where the ARM acquire fence will be performed even when we are not releaseing the last reference. This is pretty much equivalent semantically, but avoids false-positive TSAN reports.
Tackles #543.