This change address bug 38641
The select_meta test has a directly related case in it that maps to the bug test case in https://bugs.llvm.org/show_bug.cgi?id=38641
Add a test with FMF too since that was the motivation for rL339938?
Code change LGTM.
Actually the other test in rL339938 shows the positive side, where both binops are fast to show the intersection in /test/Transforms/LoopVectorize/reduction.ll