peephole optimize type refinements (#31024)
Summary:
Peephole optimize out type refinements when they are no longer refining the type.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/31024
Differential Revision: D18920958
Pulled By: eellison
fbshipit-source-id: 6d05d9812b9f9dcf001de760a78a2042fb832773
