Implement loop splitting analysis.

Determine which loop exit blocks need a 'pre-exit' block inserted.
Recognize when this would be impossible.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@108941 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Analysis/LoopInfo.h

@@ -509,6 +509,12 @@ protected:
   }
 };
 
+template<class BlockT, class LoopT>
+raw_ostream& operator<<(raw_ostream &OS, const LoopBase<BlockT, LoopT> &Loop) {
+  Loop.print(OS);
+  return OS;
+}
+
 class Loop : public LoopBase<BasicBlock, Loop> {
 public:
   Loop() {}