[llvm] [InstCombine] Add additional known bits info for self multiply (PR #151202)

[Yingwei Zheng via llvm-commits]

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

LG. Although this patch doesn't demonstrate its usefulness in real-world code, I think it is still acceptable, as the generalization is almost free.
Please wait for additional approval from other reviewers.


https://github.com/llvm/llvm-project/pull/151202