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

[Guy David via llvm-commits]

guy-david wrote:

> ```
> clang -target armv7-w64-mingw32 y4minput-preproc.c -c -o y4minput.c.o -O2
> ```

Sorry for the inconvenience. I was not able to reproduce locally, can you test whether https://github.com/llvm/llvm-project/pull/146337 fixes the issue?

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