[llvm] [SimplifyCFG] Shrink integer lookup tables (PR #202071)

[Farzon Lotfi via llvm-commits]

farzonl wrote:

This change is causing validation issues in the DirectX backend.  we are now generating `  %switch.gep5 = getelementptr inbounds nuw [3 x i8], ptr @switch.table.main, i32 0, i32 %10, !dbg !221` But DirectX doesn't support i8s.  Curious what you recommend we do to resolve this issue?

https://github.com/llvm/llvm-project/pull/202071