[llvm] [PHIElimination] Reuse existing COPY in predecessor basic block (PR #131837)

[Mikael Holmén via llvm-commits]

mikaelholmen wrote:

> Now I feel bad 😆 Can you verify whether [c4c9e0e](https://github.com/llvm/llvm-project/commit/c4c9e0eef98d9c480fcdb2604735ca855c94364d) solves the issue?

It does. Thanks! :)

https://github.com/llvm/llvm-project/pull/131837