Re-commit the safe parts of my 6/9 patch. Still working on fixing the unsafe parts.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@28748 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/Utils/LCSSA.cpp

@@ -132,6 +132,8 @@ bool LCSSA::visitSubloop(Loop* L) {
     processInstruction(*I, exitBlocks);
   }
   
+  assert(L->isLCSSAForm());
+  
   return true;
 }