Fix: Do not create nodes on fast path.

com.oracle.truffle.r.ffi.impl/src/com/oracle/truffle/r/ffi/impl/nfi/TruffleNFI_DLL.java

@@ -22,8 +22,10 @@
  */
 package com.oracle.truffle.r.ffi.impl.nfi;
 
+import com.oracle.truffle.api.CompilerDirectives;
 import com.oracle.truffle.api.CompilerDirectives.TruffleBoundary;
 import com.oracle.truffle.api.TruffleLanguage.Env;
+import com.oracle.truffle.api.dsl.Cached;
 import com.oracle.truffle.api.interop.ForeignAccess;
 import com.oracle.truffle.api.interop.InteropException;
 import com.oracle.truffle.api.interop.Message;
@@ -76,12 +78,17 @@ public class TruffleNFI_DLL implements DLLRFFI {
 
     private static class TruffleNFI_DLSymNode extends Node implements DLLRFFI.DLSymNode {
 
+        @Child private Node lookupSymbol;
+
         @Override
         @TruffleBoundary
         public SymbolHandle execute(Object handle, String symbol) {
             assert handle instanceof NFIHandle;
             NFIHandle nfiHandle = (NFIHandle) handle;
-            Node lookupSymbol = Message.READ.createNode();
+            if (lookupSymbol == null) {
+                CompilerDirectives.transferToInterpreterAndInvalidate();
+                lookupSymbol = insert(Message.READ.createNode());
+            }
             try {
                 TruffleObject result = (TruffleObject) ForeignAccess.sendRead(lookupSymbol, nfiHandle.libHandle, symbol);
                 return new SymbolHandle(result);