[llvm] [BOLT] fix race condition in multi-threaded DWO type unit processing (PR #197359)

[Amir Ayupov via llvm-commits]

https://github.com/aaupov commented:

If this is a race, can you reproduce it under TSan? You may need `-no-threads` controlling parallelism outside debug info processing.

https://github.com/llvm/llvm-project/pull/197359