--- ./Source/JavaScriptCore/assembler/AbstractMacroAssembler.h~	2020-09-20 16:08:53.156883980 +0000
+++ ./Source/JavaScriptCore/assembler/AbstractMacroAssembler.h	2020-09-20 17:18:06.814227632 +0000
@@ -918,14 +918,17 @@
     {
 #if USE(JUMP_ISLANDS)
         switch (nearCall.callMode()) {
         case NearCallMode::Tail:
             return CodeLocationLabel<destTag>(tagCodePtr<destTag>(AssemblerType::prepareForAtomicRelinkJumpConcurrently(nearCall.dataLocation(), destination.dataLocation())));
         case NearCallMode::Regular:
             return CodeLocationLabel<destTag>(tagCodePtr<destTag>(AssemblerType::prepareForAtomicRelinkCallConcurrently(nearCall.dataLocation(), destination.untaggedExecutableAddress())));
+        default:
+            UNUSED_PARAM(nearCall);
+            return destination;
         }
 #else
         UNUSED_PARAM(nearCall);
         return destination;
 #endif
     }