[llvm] [CGP] Split off switch cases with 0 and another power-of-2 const. (PR #139321)

[Florian Hahn via llvm-commits]

fhahn wrote:

> See SwitchCG::SwitchLowering::buildBitTests for similar logic.

Thanks I looked into this and I think it would require adding a new Case kind + lowering: a rough version should be here: https://github.com/llvm/llvm-project/pull/139736

It's slightly more work overall, but it means we don't need to explicitly check for consecutive cases and so on, and only will do it when no other switch-related optimizations trigger.

Would you prefer that direction?

https://github.com/llvm/llvm-project/pull/139321