[llvm] [llvm/llvm-project][Coroutines] Improve debugging and minor refactoring (PR #104642)

[Chuanqi Xu via llvm-commits]

https://github.com/ChuanqiXu9 commented:

BTW, it looks like you're doing too many different things in a PR. It will be better to separate them.

https://github.com/llvm/llvm-project/pull/104642