[llvm] [DAG] Improve known bits of Zext/Sext loads with range metadata (PR #80829)

[David Sherwood via llvm-commits]

https://github.com/david-arm commented:

Thanks for the changes @davemgreen! The patch LGTM. There was just one comment about FP extending loads. I left a comment about possibly adding an assert - do you think this it's worth doing?

https://github.com/llvm/llvm-project/pull/80829