[llvm] [Coroutines] Only rematerialize when operands are available after the suspend (PR #209195)

[Weibo He via llvm-commits]

https://github.com/NewSigma commented:

The overall idea makes sense to me. I think rematerialization requires something like a cost model, and operands that are unavailable after suspension would introduce additional materialization cost.

https://github.com/llvm/llvm-project/pull/209195