often expressed as "x >= y ? x : y", there is a good chance we can extract
the existing "x >= y" from it and use that as a replacement for "max(x,y)==x".
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@131049 91177308-0d34-0410-b5e6-96231b3b80d8