CodeGeneration: Support only simple regions

llvm-svn: 131351
diff --git a/polly/lib/CodeGeneration.cpp b/polly/lib/CodeGeneration.cpp
index 1f53ba5..1f2b88e 100644
--- a/polly/lib/CodeGeneration.cpp
+++ b/polly/lib/CodeGeneration.cpp
@@ -1364,6 +1364,8 @@
       return false;
     }
 
+    assert(R->isSimple() && "Only simple regions supported");
+
     createSeSeEdges(R);
 
     // Create a basic block in which to start code generation.