Merge branch 'main' of https://github.com/SeaOfNodes/Simple

2 files changed, 9 insertions, 6 deletions

diff --git a/chapter04/README.md b/chapter04/README.md
index a7b223b4..272d0b8d 100644
--- a/chapter04/README.md
+++ b/chapter04/README.md
@@ -39,10 +39,13 @@ Following are revised or new nodes
 |-----------|----------------|------------------------------------------------|-----------------------|----------------------------------------------------------------------------|
 | MultiNode | Abstract class | A node that has a tuple result                 |                       | A tuple                                                                    |
 | Start     | Control        | Start of function, now a MultiNode             |                       | A tuple with a ctrl token and an `arg` data node                           |
-| Proj      | Data           | Projection nodes extract values from MultiNode | A MultiNode and index | Result is the extracted value from the input MultiNode at offset index     |
+| Proj      | Data / Control | Projection nodes extract values from MultiNode | A MultiNode and index | Result is the extracted value from the input MultiNode at offset index     |
 | Bool      | Data           | Represents results of a comparison operator    | Two data nodes        | Result is a comparison, represented as integer value where 1=true, 0=false |
 | Not       | Data           | Logical not                                    | One data node         | Result converts 0 to 1 and vice versa                                      |
 
+> A `Proj` is a control node when it projects the control slot: `Proj#0` off `Start`.
+> Every other projection is a data node.  See `ProjNode.isCFG()`.
+
 Below is our list of Nodes from [Chapter 3](../chapter03/README.md):
 
 | Node Name | Type         | Description                        | Inputs                                                           | Value                        |
diff --git a/chapter04/src/main/java/com/seaofnodes/simple/node/AddNode.java b/chapter04/src/main/java/com/seaofnodes/simple/node/AddNode.java
index 5720aca4..7e08a207 100644
--- a/chapter04/src/main/java/com/seaofnodes/simple/node/AddNode.java
+++ b/chapter04/src/main/java/com/seaofnodes/simple/node/AddNode.java
@@ -63,7 +63,7 @@ public class AddNode extends Node {
 
         // Now we might see (add add non) or (add non non) but never (add non add) nor (add add add)
         if( !(lhs instanceof AddNode) )
-            return spline_cmp(lhs,rhs) ? swap12() : null;
+            return spine_cmp(lhs,rhs) ? swap12() : null;
 
         // Now we only see (add add non)
 
@@ -72,22 +72,22 @@ public class AddNode extends Node {
         if( lhs.in(2)._type.isConstant() && t2.isConstant() )
             return new AddNode(lhs.in(1),new AddNode(lhs.in(2),rhs).peephole());
 
-        // Now we sort along the spline via rotates, to gather similar things together.
+        // Now we sort along the spine via rotates, to gather similar things together.
 
         // Do we rotate (x + y) + z
         // into         (x + z) + y ?
-        if( spline_cmp(lhs.in(2),rhs) )
+        if( spine_cmp(lhs.in(2),rhs) )
             return new AddNode(new AddNode(lhs.in(1),rhs).peephole(),lhs.in(2));
 
         return null;
     }
 
-    // Compare two off-spline nodes and decide what order they should be in.
+    // Compare two off-spine nodes and decide what order they should be in.
     // Do we rotate ((x + hi) + lo) into ((x + lo) + hi) ?
     // Generally constants always go right, then others.
     // Ties with in a category sort by node ID.
     // TRUE if swapping hi and lo.
-    static boolean spline_cmp( Node hi, Node lo ) {
+    static boolean spine_cmp( Node hi, Node lo ) {
         if( lo._type.isConstant() ) return false;
         if( hi._type.isConstant() ) return true ;