diff --git a/runtime/Java/src/org/antlr/v4/runtime/nfa/NFA.java b/runtime/Java/src/org/antlr/v4/runtime/nfa/NFA.java
index 81928f381..3634e89d5 100644
--- a/runtime/Java/src/org/antlr/v4/runtime/nfa/NFA.java
+++ b/runtime/Java/src/org/antlr/v4/runtime/nfa/NFA.java
@@ -70,7 +70,7 @@ processOneChar:
 				ip = t.addr;
 				NFAStack context = t.context;
 				int alt = t.alt;
-				System.out.println("input["+input.index()+"]=="+(char)c+" closure="+closure+", i="+i+", reach="+ reach);
+				//System.out.println("input["+input.index()+"]=="+(char)c+" closure="+closure+", i="+i+", reach="+ reach);
 				trace(ip);
 				short opcode = code[ip];
 				ip++; // move to next instruction or first byte of operand
@@ -284,7 +284,7 @@ processOneChar:
 processOneChar:
 			while ( i<closure.size() ) {
 			//for (int i=0; i<closure.size(); i++) {
-				System.out.println("input["+input.index()+"]=="+(char)c+" closure="+closure+", i="+i+", reach="+ reach);
+				//System.out.println("input["+input.index()+"]=="+(char)c+" closure="+closure+", i="+i+", reach="+ reach);
 				ip = closure.get(i); 
 				trace(ip);
 				short opcode = code[ip];
diff --git a/tool/src/org/antlr/v4/codegen/NFABytecodeGenerator.java b/tool/src/org/antlr/v4/codegen/NFABytecodeGenerator.java
index b36320309..b1b934c79 100644
--- a/tool/src/org/antlr/v4/codegen/NFABytecodeGenerator.java
+++ b/tool/src/org/antlr/v4/codegen/NFABytecodeGenerator.java
@@ -5,6 +5,7 @@ import org.antlr.runtime.Token;
 import org.antlr.runtime.tree.CommonTreeNodeStream;
 import org.antlr.runtime.tree.TreeNodeStream;
 import org.antlr.v4.codegen.nfa.*;
+import org.antlr.v4.misc.DoubleKeyMap;
 import org.antlr.v4.parse.ANTLRParser;
 import org.antlr.v4.parse.GrammarASTAdaptor;
 import org.antlr.v4.runtime.nfa.Bytecode;
@@ -27,13 +28,21 @@ public class NFABytecodeGenerator extends TreeParser {
 	Map<String, Integer> ruleToAddr = new HashMap<String, Integer>();
 	int[] tokenTypeToAddr;
 
-	Map<Rule, Map<String, Integer>> ruleLabels = new HashMap<Rule, Map<String, Integer>>();
-	Map<Rule, Map<Token, Integer>> ruleActions = new HashMap<Rule, Map<Token, Integer>>();
-	Map<Rule, Map<Token, Integer>> ruleSempreds = new HashMap<Rule, Map<Token, Integer>>();
+	DoubleKeyMap<Rule, String, Integer> ruleLabels = new DoubleKeyMap<Rule, String, Integer>();
+	DoubleKeyMap<Rule, Token, Integer> ruleActions = new DoubleKeyMap<Rule, Token, Integer>();
+	DoubleKeyMap<Rule, Token, Integer> ruleSempreds = new DoubleKeyMap<Rule, Token, Integer>();
 
 	public Rule currentRule;
 
-	public int labelIndex = 0;
+	public int labelIndex = 0; // first time we ask for labels we index
+
+//	public abstract class LabelMaker<Key,Label> {
+//		Map<Key,Label> labels = new HashMap<Key,Label>();
+//		public LabelMaker(Collection<Key> keys) {
+//			for (Key k : keys) labels.put(k, computeLabel(k));
+//		}
+//		public abstract Label computeLabel(Key k);
+//	}
 
 	public NFABytecodeGenerator(TreeNodeStream input, RecognizerSharedState state) {
 		super(input, state);
@@ -49,36 +58,22 @@ public class NFABytecodeGenerator extends TreeParser {
 
 	// indexed from 0 per rule
 	public int getActionIndex(Rule r, Token actionToken) {
-		Map<Token, Integer> actions = ruleActions.get(r);
-		if ( actions==null ) {
-			actions = new HashMap<Token, Integer>();
-			ruleActions.put(r, actions);
-		}
-		if ( actions.get(actionToken)!=null ) {
-			return actions.get(actionToken);
-		}
-		else {
-			int i = actions.size();
-			actions.put(actionToken, i);
-			return i;
-		}
+		Integer I = ruleActions.get(r, actionToken);
+		if ( I!=null ) return I; // already got its label
+		Map<Token, Integer> labels = ruleActions.get(r);
+		int i = labels.size();
+		ruleActions.put(r, actionToken, i);
+		return i;
 	}
 
 	// indexed from 0 per rule
 	public int getSempredIndex(Rule r, Token actionToken) {
-		Map<Token, Integer> actions = ruleSempreds.get(r);
-		if ( actions==null ) {
-			actions = new HashMap<Token, Integer>();
-			ruleSempreds.put(r, actions);
-		}
-		if ( actions.get(actionToken)!=null ) {
-			return actions.get(actionToken);
-		}
-		else {
-			int i = actions.size();
-			actions.put(actionToken, i);
-			return i;
-		}
+		Integer I = ruleSempreds.get(r, actionToken);
+		if ( I!=null ) return I; // already got its label
+		Map<Token, Integer> labels = ruleSempreds.get(r);
+		int i = labels.size();
+		ruleSempreds.put(r, actionToken, i);
+		return i;
 	}
 
 	/** labels in all rules share single label space
@@ -86,18 +81,11 @@ public class NFABytecodeGenerator extends TreeParser {
 	 *  to an index in an action.
 	 */
 	public int getLabelIndex(Rule r, String labelName) {
-		Map<String, Integer> labels = ruleLabels.get(r);
-		if ( labels==null ) {
-			labels = new HashMap<String, Integer>();
-			ruleLabels.put(r, labels);
-		}
-		if ( labels.get(labelName)!=null ) {
-			return labels.get(labelName);
-		}
-		else {
-			labels.put(labelName, labelIndex);
-			return labelIndex++;
-		}
+		Integer I = ruleLabels.get(r, labelName);
+		if ( I!=null ) return I; // already got its label
+		int i = labelIndex++;
+		ruleLabels.put(r, labelName, i);
+		return i;
 	}
 
 	public void emitString(Token t) {
diff --git a/tool/src/org/antlr/v4/misc/DoubleKeyMap.java b/tool/src/org/antlr/v4/misc/DoubleKeyMap.java
new file mode 100644
index 000000000..5619ec143
--- /dev/null
+++ b/tool/src/org/antlr/v4/misc/DoubleKeyMap.java
@@ -0,0 +1,37 @@
+package org.antlr.v4.misc;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/** Sometimes we need to map a key to a value but key is two pieces of data.
+ *  This nested hash table saves creating a single key each time we access
+ *  map; avoids mem creation.
+ */
+public class DoubleKeyMap<Key1, Key2, Value> {
+	Map<Key1, Map<Key2, Value>> data = new HashMap<Key1, Map<Key2, Value>>();
+
+	public Value put(Key1 k1, Key2 k2, Value v) {
+		Map<Key2, Value> data2 = data.get(k1);
+		Value prev = null;
+		if ( data2==null ) {
+			data2 = new HashMap<Key2, Value>();
+			data.put(k1, data2);
+		}
+		else {
+			prev = data2.get(k2);
+		}
+		data2.put(k2, v);
+		return prev;
+	}
+
+	public Value get(Key1 k1, Key2 k2) {
+		Map<Key2, Value> data2 = data.get(k1);
+		if ( data2==null ) {
+			data2 = new HashMap<Key2, Value>();
+			data.put(k1, data2);
+		}
+		return data2.get(k2);
+	}
+
+	public Map<Key2, Value> get(Key1 k1) { return data.get(k1); }
+}