[llvm] [SLP] Make getSameOpcode support interchangeable instructions. (PR #127450)

[Jordan Rupprecht via llvm-commits]

rupprecht wrote:

Thanks @mstorsjo for reverting!

> Cannot reproduce the error. My SHA-1 is [71a0cfd](https://github.com/llvm/llvm-project/commit/71a0cfd93263552ddc0bfd2ea7b0abe9a578f87e). Do you miss anything?

Very certain it's this commit. Did you enable asserts in your local build? Hopefully the other repros can increase the chance of reproducability for you.

https://github.com/llvm/llvm-project/pull/127450