2 files changed, 9 insertions, 5 deletions
diff --git a/chapter06/src/main/java/com/seaofnodes/simple/node/DivNode.java b/chapter06/src/main/java/com/seaofnodes/simple/node/DivNode.java
index bf025453..519a8c8a 100644
--- a/chapter06/src/main/java/com/seaofnodes/simple/node/DivNode.java
+++ b/chapter06/src/main/java/com/seaofnodes/simple/node/DivNode.java
@@ -31,7 +31,12 @@ public class DivNode extends Node {
     }
 
     @Override
-    public Node idealize() { return null; }
+    public Node idealize() {
+        // Div of 1.
+        if( in(2)._type.isConstant() && in(2)._type instanceof TypeInteger i && i.value()==1 )
+            return in(1);
+        return null;
+    }
 
     @Override Node copy(Node lhs, Node rhs) { return new DivNode(lhs,rhs); }
 }
diff --git a/chapter06/src/main/java/com/seaofnodes/simple/node/SubNode.java b/chapter06/src/main/java/com/seaofnodes/simple/node/SubNode.java
index 0d0ed7dc..5e7243ba 100644
--- a/chapter06/src/main/java/com/seaofnodes/simple/node/SubNode.java
+++ b/chapter06/src/main/java/com/seaofnodes/simple/node/SubNode.java
@@ -25,15 +25,14 @@ public class SubNode extends Node {
                 return TypeInteger.constant(i0.value()-i1.value());
             return i0.meet(i1);
         }
+        // Sub of same is 0
+        if( in(1)==in(2) )
+            return TypeInteger.ZERO;
         return Type.BOTTOM;
     }
 
     @Override
     public Node idealize() {
-        // Sub of same is 0
-        if( in(1)==in(2) )
-            return new ConstantNode(TypeInteger.constant(0));
-
         return null;
     }