diff -r 970abfc9f077 -r b029d63565a2 src/BytecodeEmitter.h
--- a/src/BytecodeEmitter.h	Sun Sep 16 23:33:48 2012 -0700
+++ b/src/BytecodeEmitter.h	Mon Sep 17 00:10:01 2012 -0700
@@ -528,6 +528,9 @@
         singleByteOp(OP_COPYSTRUCT);
         markOop(1);
     }
+    void sizeof_() {
+        singleByteOp(OP_SIZEOF);
+    }
 
     void dup() {
         bool oop = getOop(1);