[llvm] [llvm][CodeGen] Intrinsic `llvm.powi.*` code gen for vector arguments (PR #118242)

[Craig Topper via llvm-commits]

topperc wrote:

I kind of think this should be handled by unrolling the vector in `DAGTypeLegalizer::PromoteIntOp_ExpOp`.

https://github.com/llvm/llvm-project/pull/118242