[llvm] [MemCpyOpt] lifetime markers reconstruction for Stack-move optimization (PR #68990)

[Kohei Asano via llvm-commits]

khei4 wrote:

> Can you elaborate a bit what is missing? 

Sure.

> Shepherding through review, or is it not done?

Not done yet. So I guess the first thing to be done is to verify this is correct to some kind. This patch introduces more lifetime than current main, so checking sanitizer won't crash for sufficient tests may be good. 

https://github.com/llvm/llvm-project/pull/68990