If MaxVFOnly for buildvector/buildvalue vectorization is set to true and the
total number of elements to vectorize is <= 2, better to try to
vectorize reductions at first, which may produce larger tree (reductions
have a limit of at least 4 elements to vectorize). Smaller
buildvector/buildvalue sequence will be attempted to vectorize later,
with MaxVFOnly set to false.
Reviewers: RKSimon
Reviewed By: RKSimon
Pull Request: https://github.com/llvm/llvm-project/pull/98957
15915c06d5