PING^2: [PATCH v3] eliminate mutex in fast path of __register_frame

[Thomas Neumann via Gcc-patches]

Summary: __register_frame and the corresponding _Unwind_Find_FDE use a 
global mutex for frame registration and unwinding. This can lead to very 
poor performance on machines with high core counts. This patch organizes 
the frames in a b-tree with read-optimized synchronization instead, 
which allows for fully parallel unwinding.

See:
https://gcc.gnu.org/pipermail/gcc-patches/2022-June/597256.html
Best

Thomas