LoopRotate wanted to avoid live range interference by looking at the
uses of a Value in the loop latch and seeing if any lied outside of the
loop. We would wrongly perform this operation on Constants.
This fixes PR22337.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@227171 91177308-0d34-0410-b5e6-96231b3b80d8
David Majnemer