[llvm] [SLP] Make getSameOpcode support interchangeable instructions. (PR #132887)

[Alexander Kornienko via llvm-commits]

alexfh wrote:

We see a Clang crash after 8122bb9dbe39a1dde77eb4aad76bf1c0e70b2d89 and this commit (unfortunately, I don't know yet more precisely, which of the two is the culprit). See https://github.com/llvm/llvm-project/commit/8122bb9dbe39a1dde77eb4aad76bf1c0e70b2d89#commitcomment-154471110

https://github.com/llvm/llvm-project/pull/132887