[llvm] Make DWARFUnitVector threadsafe. (PR #71487)

[David Blaikie via llvm-commits]

dwblaikie wrote:

Could you check the history and describe why the lazy feature was added (I'd guess I probably added it for symbolizing performance, or for other DWP usage performance) and why this change ensures those needs are still addressed?

> not thread safe and causes crashes

Does it cause crashes in non-multithreaded situations? If not, then it may be hard to justify pessimizing the non-multithreaded usage to fix the threaded usage without some more nuance about how to address these different needs.


https://github.com/llvm/llvm-project/pull/71487