19b0c68ee0
When narrowing interleave groups, the main vector loop processes IC iterations instead of VF * IC. Update selectEpilogueVectorizationFactor to use the effective VF, checking if the canonical IV controlling the loop now steps by UF instead of VFxUF. This avoids epilogue vectorization with dead epilogue vector loops and also prevents crashes in cases where we can prove both the epilogue and scalar loop are dead. Fixes https://github.com/llvm/llvm-project/issues/186846 PR: https://github.com/llvm/llvm-project/pull/187016