nodes unless we KNOW that we are able to promote all of them. In this case
promoting the phi to a select is silly because we will always have to do the
call conditionally. As such, select promotion is actually a pessimization.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@16972 91177308-0d34-0410-b5e6-96231b3b80d8
