Update various Loop optimization passes to cope with the possibility that
LoopSimplify form may not be available.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86175 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/LoopRotation.cpp b/lib/Transforms/Scalar/LoopRotation.cpp
index a18d9d4..5004483 100644
--- a/lib/Transforms/Scalar/LoopRotation.cpp
+++ b/lib/Transforms/Scalar/LoopRotation.cpp
@@ -104,17 +104,18 @@
 bool LoopRotate::rotateLoop(Loop *Lp, LPPassManager &LPM) {
   L = Lp;
 
-  OrigHeader =  L->getHeader();
   OrigPreHeader = L->getLoopPreheader();
+  if (!OrigPreHeader) return false;
+
   OrigLatch = L->getLoopLatch();
+  if (!OrigLatch) return false;
+
+  OrigHeader =  L->getHeader();
 
   // If the loop has only one block then there is not much to rotate.
   if (L->getBlocks().size() == 1)
     return false;
 
-  assert(OrigHeader && OrigLatch && OrigPreHeader &&
-         "Loop is not in canonical form");
-
   // If the loop header is not one of the loop exiting blocks then
   // either this loop is already rotated or it is not
   // suitable for loop rotation transformations.