[clang] [llvm] [clang][CodeGen] Extends lifetime of coroutine promise(CWG2563) (PR #151067)

[Chuanqi Xu via llvm-commits]

ChuanqiXu9 wrote:

I don't understand this: 

> Do not lower coro.end to ret void if its return value will be used. This allows front end separate coro start section and resume section without early return from resume function.

Could elaborate it? Especially why it is safe to not lower  `coro.end` to `ret void`?

https://github.com/llvm/llvm-project/pull/151067