[llvm] [DAGTypeLegalize] Legalize ISD::POISON as ISD::UNDEF for Float Type Legalization (PR #135056)

[Alexander Richardson via llvm-commits]

https://github.com/arichardson approved this pull request.

I would suggest using update_llc_test_checks.py (and adding nounwind to ensure it doesn't add the cfi information), otherwise this change LGTM.

But since I'm not a SelectionDAG expert please wait for someone else to approve too.

https://github.com/llvm/llvm-project/pull/135056