[llvm] [InstCombine] Fold splice.right(splice.left(poison, x, offset), poison, offset) -> x (PR #204256)

[Luke Lau via llvm-commits]

https://github.com/lukel97 approved this pull request.

LGTM, let me know if you'd like me to merge this for you

https://github.com/llvm/llvm-project/pull/204256