add comments
diff --git a/xbyak/xbyak_util.h b/xbyak/xbyak_util.h
index a43d98a..2bb215a 100644
--- a/xbyak/xbyak_util.h
+++ b/xbyak/xbyak_util.h
@@ -649,7 +649,7 @@
 template<int dummy> const Type CpuT<dummy>::tCLDEMOTE = Type(0, 1 << 0);
 template<int dummy> const Type CpuT<dummy>::tMOVDIRI = Type(0, 1 << 1);
 template<int dummy> const Type CpuT<dummy>::tMOVDIR64B = Type(0, 1 << 2);
-template<int dummy> const Type CpuT<dummy>::tCLZERO = Type(0, 1 << 3);
+template<int dummy> const Type CpuT<dummy>::tCLZERO = Type(0, 1 << 3); // AMD Zen
 
 } // local