llvm-project

8680feb9 - [libc++] Use native wait in std::barrier instead of sleep loop (#171041)

[libc++] Use native wait in std::barrier instead of sleep loop (#171041) For some reason, the current `std::barrier`'s wait implementation polls the underlying atomic in a loop with sleeps instead of using the native wait. This change should also indirectly fix the performance issue of `std::barrier` described in https://github.com/llvm/llvm-project/issues/123855. Fixes #123855