db98ac43ec
Directly emit shl instead of a multiply if VF * Step is a power-of-2. The main motivation here is to prepare the code and test for directly generating and expanding a SCEV expression of the minimum iteration count. SCEVExpander will directly emit shl for multiplies with powers-of-2. InstCombine will also performs this combine, so end-to-end this should effectively by NFC. PR: https://github.com/llvm/llvm-project/pull/153495