Index: llvm/trunk/lib/Transforms/Utils/LCSSA.cpp
===================================================================
--- llvm/trunk/lib/Transforms/Utils/LCSSA.cpp
+++ llvm/trunk/lib/Transforms/Utils/LCSSA.cpp
@@ -305,6 +305,12 @@
                      ScalarEvolution *SE) {
   bool Changed = false;
 
+#ifdef EXPENSIVE_CHECKS
+  // Verify all sub-loops are in LCSSA form already.
+  for (Loop *SubLoop: L)
+    assert(SubLoop->isRecursivelyLCSSAForm(DT, *LI) && "Subloop not in LCSSA!");
+#endif
+
   SmallVector<BasicBlock *, 8> ExitBlocks;
   L.getExitBlocks(ExitBlocks);
   if (ExitBlocks.empty())