Fix stale copy-pasted comment on BoolNode's phiCon call (#249)

The three comment lines above `AddNode.phiCon(this, ...)` in BoolNode were
copy-pasted from MulNode and never adapted: they use `*` as the operator and
describe the rotated shape `(x * (phi cons)) * con`.

For BoolNode neither is right. The operator is a compare, and in chapters
6-9 `rotate` is hard-coded `false`, so the rotated shape is never matched;
the shapes actually handled are `(phi cons) cmp con` and
`(phi cons) cmp (phi cons)`.

Reword the comment accordingly, and in chapters 6-9 add a line noting why
rotate is off. Chapters 10-25 pass `this instanceof EQ`, so no such claim is
made there.

Comment-only change; no code is touched.

Co-authored-by: Claude Opus 5 <noreply@anthropic.com>

1 files changed, 4 insertions, 3 deletions

diff --git a/chapter09/src/main/java/com/seaofnodes/simple/node/BoolNode.java b/chapter09/src/main/java/com/seaofnodes/simple/node/BoolNode.java
index d3fcec95..ee643bf5 100644
--- a/chapter09/src/main/java/com/seaofnodes/simple/node/BoolNode.java
+++ b/chapter09/src/main/java/com/seaofnodes/simple/node/BoolNode.java
@@ -44,9 +44,10 @@ abstract public class BoolNode extends Node {
         if( in(1)==in(2) )
             return new ConstantNode(TypeInteger.constant(doOp(3,3)?1:0));
 
-        // Do we have ((x * (phi cons)) * con) ?
-        // Do we have ((x * (phi cons)) * (phi cons)) ?
-        // Push constant up through the phi: x * (phi con0*con0 con1*con1...)
+        // Do we have ((phi cons) cmp con) ?
+        // Do we have ((phi cons) cmp (phi cons)) ?
+        // Push the compare up through the phi: (phi con0 cmp con, con1 cmp con...)
+        // No rotate: compares are not associative.
         Node phicon = AddNode.phiCon(this,false);
         if( phicon!=null ) return phicon;