This moves the actual work to do loop rotation into standalone
functions with the analysis results they need passed in as arguments,
leaving the class itself as a relatively simple shim. This will make
the functions easy to reuse when we're ready to port this
transformation to the new pass manager.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@255574 91177308-0d34-0410-b5e6-96231b3b80d8