[llvm] [SimplifyCFG] Improve range reducing for switches (PR #67882)

[via llvm-commits]

DianQK wrote:

But your PR seems to be a special case of handling discontinuous values? Is it possible to handle this type of issue like https://github.com/rust-lang/rust/issues/114106#issuecomment-1657131825 does.

https://github.com/llvm/llvm-project/pull/67882