[llvm] [coro][CoroSplit] Use `llvm.lifetime.end` to compute putting objects on the frame vs the stack (PR #90265)

[Nikita Popov via llvm-commits]

nikic wrote:

Reverted in https://github.com/llvm/llvm-project/commit/924384161ffceda08099536dd07a953299a69b53 due to compile-time regressions, see https://llvm-compile-time-tracker.com/compare.php?from=94204f59e92473bb19333f40a2250b64a398191a&to=fcf341d3ddfe2289ac88aa3c122b25df8732cc8e&stat=instructions:u. Presumably your changes to the isPotentiallyReachable infrastructure have made it much slower than it was.

https://github.com/llvm/llvm-project/pull/90265