Fix MSVC "not all control paths return a value" warning. NFCI.
diff --git a/llvm/lib/Target/SPIRV/SPIRVGlobalRegistry.cpp b/llvm/lib/Target/SPIRV/SPIRVGlobalRegistry.cpp
index 1858b9e..cc01a6d 100644
--- a/llvm/lib/Target/SPIRV/SPIRVGlobalRegistry.cpp
+++ b/llvm/lib/Target/SPIRV/SPIRVGlobalRegistry.cpp
@@ -83,6 +83,7 @@
   case SPIRV::StorageClass::HostOnlyINTEL:
     return false;
   }
+  llvm_unreachable("Unknown SPIRV::StorageClass enum");
 }
 
 SPIRVGlobalRegistry::SPIRVGlobalRegistry(unsigned PointerSize)