[llvm] [MCP] Move dependencies if they block copy propagation (PR #105562)

[Kai Luo via llvm-commits]

bzEq wrote:

I'm still concerned about introducing rescheduling instructions in MCP. Is there possibility we enhance pre-RA machine scheduler to achieve the same effect?
For example, changes in `llvm/test/CodeGen/AArch64/GlobalISel/arm64-atomic.ll` can be also achieved by disabling pre-RA machine scheduling, i.e., `-enable-misched=0`.

https://github.com/llvm/llvm-project/pull/105562