simplify AccessEnclosingFrameNode

com.oracle.truffle.r.nodes/src/com/oracle/truffle/r/nodes/access/AccessEnclosingFrameNode.java

@@ -24,27 +24,15 @@ package com.oracle.truffle.r.nodes.access;
 
 import com.oracle.truffle.api.dsl.*;
 import com.oracle.truffle.api.frame.*;
-import com.oracle.truffle.api.nodes.*;
 import com.oracle.truffle.r.nodes.*;
 import com.oracle.truffle.r.runtime.*;
 
-@NodeField(name = "level", type = int.class)
 public abstract class AccessEnclosingFrameNode extends RNode {
 
-    @Override
-    public final Object execute(VirtualFrame frame) {
-        return executeMaterializedFrame(frame);
-    }
-
     public abstract MaterializedFrame executeMaterializedFrame(VirtualFrame frame);
 
     @Specialization
-    @ExplodeLoop
-    protected MaterializedFrame doMaterializedFrame(VirtualFrame frame, int level) {
-        MaterializedFrame enclosingFrame = RArguments.getFunction(frame).getEnclosingFrame();
-        for (int i = 1; i < level; i++) {
-            enclosingFrame = RArguments.getFunction(enclosingFrame).getEnclosingFrame();
-        }
-        return enclosingFrame;
+    protected MaterializedFrame doMaterializedFrame(VirtualFrame frame) {
+        return RArguments.getEnclosingFrame(frame);
     }
 }

com.oracle.truffle.r.nodes/src/com/oracle/truffle/r/nodes/access/WriteSuperFrameVariableNode.java

@@ -116,7 +116,7 @@ public abstract class WriteSuperFrameVariableNode extends WriteSuperFrameVariabl
                  * we've reached the global scope, do unconditional write // if this is the first
                  * node in the chain, needs the rhs and enclosingFrame // nodes
                  */
-                AccessEnclosingFrameNode enclosingFrameNode = RArguments.getEnclosingFrame(frame) == enclosingFrame ? AccessEnclosingFrameNodeGen.create(1) : null;
+                AccessEnclosingFrameNode enclosingFrameNode = RArguments.getEnclosingFrame(frame) == enclosingFrame ? AccessEnclosingFrameNodeGen.create() : null;
                 writeNode = WriteSuperFrameVariableNodeGen.create(getRhs(), enclosingFrameNode, FrameSlotNode.create(findOrAddFrameSlot(enclosingFrame.getFrameDescriptor(), symbol)), getName(), mode);
             } else {
                 WriteSuperFrameVariableNode actualWriteNode = WriteSuperFrameVariableNodeGen.create(null, null, FrameSlotNode.create(symbol), this.getName(), mode);