[llvm] [SDAG] Handle extract_subvector in isKnownNeverNaN (PR #131581)

[Jim Lin via llvm-commits]

tclin914 wrote:

> LGTM
> 
> Might be worth checking, do we get the insert subvector into undef vector case?

Candidate patch: https://github.com/llvm/llvm-project/pull/131989

https://github.com/llvm/llvm-project/pull/131581