diff --git a/lib/ExecutionEngine/SectionMemoryManager.cpp b/lib/ExecutionEngine/SectionMemoryManager.cpp
index 2436bb19491..2dc66a1502f 100644
--- a/lib/ExecutionEngine/SectionMemoryManager.cpp
+++ b/lib/ExecutionEngine/SectionMemoryManager.cpp
@@ -59,6 +59,7 @@ uint8_t *SectionMemoryManager::allocateSection(
     case AllocationPurpose::RWData:
       return RWDataMem;
     }
+    llvm_unreachable("Unknown SectionMemoryManager::AllocationPurpose");
   }();
 
   // Look in the list of free memory regions and use a block there if one