[llvm] [MachineLICM] Hoist copies of constant physical register (PR #93285)

[Pengcheng Wang via llvm-commits]

wangpc-pp wrote:

Background: I'm doing some auto-vectorization evaluations of x264 hotspots on RISCV. This change can improve codegen vector reductions as we can hoist the initial zero value.

https://github.com/llvm/llvm-project/pull/93285