[Bug sanitizer/78158] Strange data race detection with thread sanitizer

[dvyukov at google dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78158

--- Comment #8 from Dmitry Vyukov <dvyukov at google dot com> ---
We need to modify tsan runtime to ignore (zero) __ATOMIC_HLE_ACQUIRE/RELEASE
bits, right? It's only an optimization and we can pretend that elision never
succeeds under tsan.

What is sync special bit (0x4000)?