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02a25279ae
Correct the logic used to set `ATOMIC_*_LOCK_FREE` preprocessor macros not to rely on the ABI alignment of types. Instead, just assume all those types are aligned correctly by default since clang uses safe alignment for `_Atomic` types even if the underlying types are aligned to a lower boundary by default. For example, the `long long` and `double` types on x86 are aligned to 32-bit boundary by default. However, `_Atomic long long` and `_Atomic double` are aligned to 64-bit boundary, therefore satisfying the requirements of lock-free atomic operations. This fixes PR #19355 by correcting the value of `__GCC_ATOMIC_LLONG_LOCK_FREE` on x86, and therefore also fixing the assumption made in libc++ tests. This also fixes PR #30581 by applying a consistent logic between the functions used to implement both interfaces. Reviewed By: hfinkel, efriedma Differential Revision: https://reviews.llvm.org/D28213