[llvm] [SelectionDAG] Treat CopyFromReg as freezing the value (PR #85932)

[Yingwei Zheng via llvm-commits]

dtcxzyw wrote:

Reverse ping. At least you can rebase to resolve conflicts.
I believe this patch will eliminate a ton of `andi gpr, 1` instructions on RISCV :)


https://github.com/llvm/llvm-project/pull/85932