Recursive sharing bug is no issue anymore in the new DSL layout.

com.oracle.truffle.r.nodes/src/com/oracle/truffle/r/nodes/builtin/RBuiltinNode.java

@@ -22,7 +22,6 @@
  */
 package com.oracle.truffle.r.nodes.builtin;
 
-import java.lang.reflect.*;
 import java.util.*;
 
 import com.oracle.truffle.api.*;
@@ -130,41 +129,6 @@ public abstract class RBuiltinNode extends LeafCallNode implements VisibilityCon
         return executeDouble(frame);
     }
 
-    /**
-     * WORKAROUND for recursive sharing bug. A shallow copy is insufficient because is can cause
-     * shared state in the {@code arguments} field to be overwritten during a re-specialization.
-     * This is an ugly fix that uses reflection to update the hidden {@code arguments} field, and
-     * should go away with an upcoming Truffle fix.
-     */
-    @Override
-    public Node copy() {
-        RBuiltinNode copy = (RBuiltinNode) super.copy();
-        RNode[] args = getArguments();
-        RNode[] copyArgs = Arrays.copyOf(args, args.length);
-        try {
-            Field field = getArgumentsField(getClass());
-            field.setAccessible(true);
-            field.set(copy, copyArgs);
-        } catch (IllegalAccessException | NoSuchFieldException ex) {
-            Utils.fatalError("failed to update RBuiltinNode.arguments");
-        }
-        return copy;
-    }
-
-    /**
-     * WORKAROUND support method.
-     */
-    private Field getArgumentsField(Class<?> klass) throws NoSuchFieldException {
-        if (klass == RBuiltinNode.class) {
-            throw new NoSuchFieldException();
-        }
-        try {
-            return klass.getDeclaredField("arguments");
-        } catch (NoSuchFieldException ex) {
-            return getArgumentsField(klass.getSuperclass());
-        }
-    }
-
     private static RNode[] createAccessArgumentsNodes(RBuiltinFactory builtin) {
         int total = builtin.getRBuiltin().parameterNames().length;
         RNode[] args = new RNode[total];