diff --git a/llvm/lib/ExecutionEngine/SectionMemoryManager.cpp b/llvm/lib/ExecutionEngine/SectionMemoryManager.cpp
index 2436bb1..2dc66a1 100644
--- a/llvm/lib/ExecutionEngine/SectionMemoryManager.cpp
+++ b/llvm/lib/ExecutionEngine/SectionMemoryManager.cpp
@@ -59,6 +59,7 @@
     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