Convert assert(0) to llvm_unreachable

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@149961 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/Hexagon/HexagonCFGOptimizer.cpp b/lib/Target/Hexagon/HexagonCFGOptimizer.cpp
index 433d71c..fc46080 100644
--- a/lib/Target/Hexagon/HexagonCFGOptimizer.cpp
+++ b/lib/Target/Hexagon/HexagonCFGOptimizer.cpp
@@ -84,7 +84,7 @@
     break;
 
   default:
-    assert(0 && "Cannot handle this case");
+    llvm_unreachable("Cannot handle this case");
   }
 
   MI->setDesc(QII->get(NewOpcode));