unsplittable critical edges, which means the introduction of
loops which cannot be transformed to LoopSimplify form. Fix
LoopSimplify to avoid transforming such loops into invalid
code.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86176 91177308-0d34-0410-b5e6-96231b3b80d8
