Add shared graph viewer to all chapters

30 files changed, 130 insertions, 980 deletions

diff --git a/chapter24/src/main/java/com/seaofnodes/simple/IterPeeps.java b/chapter24/src/main/java/com/seaofnodes/simple/IterPeeps.java
index 18ff470a..c924ccea 100644
--- a/chapter24/src/main/java/com/seaofnodes/simple/IterPeeps.java
+++ b/chapter24/src/main/java/com/seaofnodes/simple/IterPeeps.java
@@ -5,7 +5,6 @@ import com.seaofnodes.simple.type.Type;
 import com.seaofnodes.simple.type.TypeInteger;
 import com.seaofnodes.simple.util.Ary;
 import com.seaofnodes.simple.node.*;
-import com.seaofnodes.simple.print.JSViewer;
 import java.util.Arrays;
 import java.util.BitSet;
 import java.util.Random;
@@ -68,9 +67,14 @@ public class IterPeeps {
         while( (n=_work.pop()) != null ) {
             if( n.isDead() )  continue;
             cnt++;              // Useful for debugging, searching which peephole broke things
+            var obs = CodeGen.CODE._obs;
+            if( obs != null ) obs.before(n);
             Node x = n.peepholeOpt();
             if( x != null ) {
-                if( x.isDead() ) continue;
+                if( x.isDead() ) {
+                    if( obs != null ) obs.after(n, x, true);
+                    continue;
+                }
                 // peepholeOpt can return brand-new nodes, needing an initial type set
                 if( x._type==null ) x.setType(x.compute());
                 // Changes require neighbors onto the worklist
@@ -90,11 +94,11 @@ public class IterPeeps {
                 }
                 // If there are distant neighbors, move to worklist
                 n.moveDepsToWorklist();
-                JSViewer.show(); // Show again
                 assert progressOnList(code, _work, true); // Very expensive assert
             }
             if( n.isUnused() && !(n instanceof StopNode) )
                 n.kill();       // Just plain dead
+            if( obs != null ) obs.after(n, x, true);
         }
 
     }
diff --git a/chapter24/src/main/java/com/seaofnodes/simple/Parser.java b/chapter24/src/main/java/com/seaofnodes/simple/Parser.java
index 1932772c..c9e53b4b 100644
--- a/chapter24/src/main/java/com/seaofnodes/simple/Parser.java
+++ b/chapter24/src/main/java/com/seaofnodes/simple/Parser.java
@@ -2,7 +2,6 @@ package com.seaofnodes.simple;
 
 import com.seaofnodes.simple.codegen.CodeGen;
 import com.seaofnodes.simple.node.*;
-import com.seaofnodes.simple.print.GraphVisualizer;
 import com.seaofnodes.simple.type.*;
 import com.seaofnodes.simple.util.Ary;
 import com.seaofnodes.simple.util.Utils;
@@ -325,7 +324,6 @@ public class Parser {
         else if (matchx("break")   ) return parseBreak();
         else if (matchx("continue")) return parseContinue();
         else if (matchx("struct")  ) return parseStruct();
-        else if (matchx("#showGraph")) return require(showGraph(),";");
         else if (matchx(";")       ) return null; // Empty statement
         // Break ambiguity around leading function types and starting a block
         else if (peek('{') && !isTypeFun() ) {
@@ -642,14 +640,7 @@ public class Parser {
         return expr;
     }
 
-    /**
-     * Dumps out the node graph
-     * @return {@code null}
-     */
-    Node showGraph() {
-        System.out.println(new GraphVisualizer().generateDotOutput(_code._stop,_scope,_xScopes));
-        return null;
-    }
+
 
     /** Parse: [name '='] expr
      */
diff --git a/chapter24/src/main/java/com/seaofnodes/simple/codegen/CodeGen.java b/chapter24/src/main/java/com/seaofnodes/simple/codegen/CodeGen.java
index 3c6e825d..d4af3a10 100644
--- a/chapter24/src/main/java/com/seaofnodes/simple/codegen/CodeGen.java
+++ b/chapter24/src/main/java/com/seaofnodes/simple/codegen/CodeGen.java
@@ -1,5 +1,7 @@
 package com.seaofnodes.simple.codegen;
 
+import com.seaofnodes.graph.GraphObserver;
+
 import com.seaofnodes.simple.IterPeeps;
 import com.seaofnodes.simple.Parser;
 import com.seaofnodes.simple.node.*;
@@ -13,6 +15,7 @@ import java.util.*;
 
 @SuppressWarnings("unchecked")
 public class CodeGen {
+    public GraphObserver<Node> _obs;
     public static final String PORTS = "com.seaofnodes.simple.node.cpus";
     // Last created CodeGen as a global; used all over to avoid passing about a
     // "context".
@@ -165,7 +168,7 @@ public class CodeGen {
 
         P.parse();
         _tParse = (int)(System.currentTimeMillis() - t0);
-        JSViewer.show();
+        if( _obs != null ) _obs.phase("Parse");
         return this;
     }
 
@@ -191,6 +194,7 @@ public class CodeGen {
         Opto.opto(this);
 
         _tOpto = (int)(System.currentTimeMillis() - t0);
+        if( _obs != null ) _obs.phase("Opto");
         return this;
     }
     public <N extends Node> N add( N n ) { return _iter.add(n); }
@@ -339,16 +343,14 @@ public class CodeGen {
     public Ary<CFGNode> _cfg = new Ary<>(CFGNode.class);
 
     // Global schedule (code motion) nodes
-    public CodeGen GCM() { return GCM(false); }
-    public CodeGen GCM( boolean show) {
+    public CodeGen GCM() {
         assert _phase.ordinal() <= Phase.Select.ordinal();
         _phase = Phase.Schedule;
         long t0 = System.currentTimeMillis();
 
         GlobalCodeMotion.buildCFG(this);
         _tGCM = (int)(System.currentTimeMillis() - t0);
-        if( show )
-            System.out.println(new GraphVisualizer().generateDotOutput(_stop,null,null));
+
         return this;
     }
 
diff --git a/chapter24/src/main/java/com/seaofnodes/simple/node/AndNode.java b/chapter24/src/main/java/com/seaofnodes/simple/node/AndNode.java
index 70b57d6d..9957472b 100644
--- a/chapter24/src/main/java/com/seaofnodes/simple/node/AndNode.java
+++ b/chapter24/src/main/java/com/seaofnodes/simple/node/AndNode.java
@@ -9,8 +9,6 @@ public class AndNode extends ArithNode {
 
     @Override public String label() { return "And"; }
     @Override public String op() { return "&"; }
-    @Override public String glabel() { return "&"; }
-
     @Override long doOp( long x, long y ) { return x & y; }
     @Override TypeInteger doOp(TypeInteger x, TypeInteger y) {
         // Sharpen allowed bits if either value is narrowed
diff --git a/chapter24/src/main/java/com/seaofnodes/simple/node/ArithNode.java b/chapter24/src/main/java/com/seaofnodes/simple/node/ArithNode.java
index f2beaacb..6c147fe8 100644
--- a/chapter24/src/main/java/com/seaofnodes/simple/node/ArithNode.java
+++ b/chapter24/src/main/java/com/seaofnodes/simple/node/ArithNode.java
@@ -11,7 +11,6 @@ public abstract class ArithNode extends Node {
     Parser.Lexer _loc;
 
     public ArithNode( Parser.Lexer loc, Node lhs, Node rhs) { super(null, lhs, rhs); _loc = loc; }
-    @Override public String glabel() { return op(); }
     abstract String op();
 
     @Override
diff --git a/chapter24/src/main/java/com/seaofnodes/simple/node/BoolNode.java b/chapter24/src/main/java/com/seaofnodes/simple/node/BoolNode.java
index 513f8d31..1a837435 100644
--- a/chapter24/src/main/java/com/seaofnodes/simple/node/BoolNode.java
+++ b/chapter24/src/main/java/com/seaofnodes/simple/node/BoolNode.java
@@ -18,9 +18,6 @@ abstract public class BoolNode extends Node {
     public String label() { return getClass().getSimpleName(); }
 
     @Override
-    public String glabel() { return op(); }
-
-    @Override
     public StringBuilder _print1(StringBuilder sb, BitSet visited) {
         in(1)._print0(sb.append("("), visited);
         in(2)._print0(sb.append(op()), visited);
@@ -107,7 +104,6 @@ abstract public class BoolNode extends Node {
     public static class LT extends BoolNode {
         public LT(Node lhs, Node rhs) { super(lhs,rhs); }
         public String op() { return "<" ; }
-        public String glabel() { return "&lt;"; }
         TypeInteger doOp(TypeInteger i1, TypeInteger i2) {
             if( i1._max <  i2._min ) return TRUE;
             if( i1._min >= i2._max ) return FALSE;
@@ -120,7 +116,6 @@ abstract public class BoolNode extends Node {
     public static class LE extends BoolNode {
         public LE(Node lhs, Node rhs) { super(lhs,rhs); }
         public String op() { return "<="; }
-        public String glabel() { return "&lt;="; }
         TypeInteger doOp(TypeInteger i1, TypeInteger i2) {
             if( i1._max <= i2._min ) return TRUE;
             if( i1._min >  i2._max ) return FALSE;
@@ -153,7 +148,6 @@ abstract public class BoolNode extends Node {
     public static class ULT extends BoolNode {
         public ULT(Node lhs, Node rhs) { super(lhs,rhs); }
         public String op() { return "u<" ; }
-        public String glabel() { return "u&lt;"; }
         TypeInteger doOp(TypeInteger i1, TypeInteger i2) {
             if( Long.compareUnsigned(i1._max,i2._min) <  0 ) return TRUE;
             if( Long.compareUnsigned(i1._min,i2._max) >= 0 ) return FALSE;
diff --git a/chapter24/src/main/java/com/seaofnodes/simple/node/ConFldOffNode.java b/chapter24/src/main/java/com/seaofnodes/simple/node/ConFldOffNode.java
index c54da2c4..56c125e2 100644
--- a/chapter24/src/main/java/com/seaofnodes/simple/node/ConFldOffNode.java
+++ b/chapter24/src/main/java/com/seaofnodes/simple/node/ConFldOffNode.java
@@ -21,7 +21,6 @@ public class ConFldOffNode extends ConstantNode {
     @Override public String label() {
         return _fname == " len" ? "sizeof("+_name+")" : "#"+_fname;
     }
-    @Override public String glabel() { return label(); }
     @Override public String uniqueName() { return "Off_" + _nid; }
 
     @Override
diff --git a/chapter24/src/main/java/com/seaofnodes/simple/node/ConstantNode.java b/chapter24/src/main/java/com/seaofnodes/simple/node/ConstantNode.java
index d5d70a0f..89289cfc 100644
--- a/chapter24/src/main/java/com/seaofnodes/simple/node/ConstantNode.java
+++ b/chapter24/src/main/java/com/seaofnodes/simple/node/ConstantNode.java
@@ -31,7 +31,6 @@ public class ConstantNode extends Node {
     }
 
     @Override public String  label() { return "#"+_con; }
-    @Override public String glabel() { return "#"+_con.gprint(); }
     @Override public String uniqueName() { return "Con_" + _nid; }
 
     @Override
diff --git a/chapter24/src/main/java/com/seaofnodes/simple/node/ExternNode.java b/chapter24/src/main/java/com/seaofnodes/simple/node/ExternNode.java
index a10bb84a..21ef8eff 100644
--- a/chapter24/src/main/java/com/seaofnodes/simple/node/ExternNode.java
+++ b/chapter24/src/main/java/com/seaofnodes/simple/node/ExternNode.java
@@ -16,7 +16,6 @@ public class ExternNode extends ConstantNode {
     public ExternNode(Type t, String ex) { super(t); _extern = ex; }
 
     @Override public String  label() { return "#"+_con+":"+_extern; }
-    @Override public String glabel() { return _con.print(new SB().p("#"), new BitSet(), true).p(":").p(_extern).toString(); }
     @Override public String uniqueName() { return "Extern_" + _nid; }
 
     @Override public boolean eq(Node n) { return this==n; }
diff --git a/chapter24/src/main/java/com/seaofnodes/simple/node/LoadNode.java b/chapter24/src/main/java/com/seaofnodes/simple/node/LoadNode.java
index 10fa9d43..b32484c2 100644
--- a/chapter24/src/main/java/com/seaofnodes/simple/node/LoadNode.java
+++ b/chapter24/src/main/java/com/seaofnodes/simple/node/LoadNode.java
@@ -24,11 +24,8 @@ public class LoadNode extends MemOpNode {
         super(loc, name, alias, true, glb, mem, ptr, off);
     }
 
-    // GraphVis DOT code (must be valid Java identifiers) and debugger labels
+    // Debugger label
     @Override public String  label() { return "ld_"+mlabel(); }
-    // GraphVis node-internal labels
-    @Override public String glabel() { return "." +_name; }
-
     @Override
     public StringBuilder _print1(StringBuilder sb, BitSet visited) { return sb.append(".").append(_name); }
 
diff --git a/chapter24/src/main/java/com/seaofnodes/simple/node/MinusFNode.java b/chapter24/src/main/java/com/seaofnodes/simple/node/MinusFNode.java
index 5bb0889f..aa66a7f0 100644
--- a/chapter24/src/main/java/com/seaofnodes/simple/node/MinusFNode.java
+++ b/chapter24/src/main/java/com/seaofnodes/simple/node/MinusFNode.java
@@ -10,8 +10,6 @@ public class MinusFNode extends Node {
 
     @Override public String label() { return "MinusF"; }
 
-    @Override public String glabel() { return "-"; }
-
     @Override
     public StringBuilder _print1(StringBuilder sb, BitSet visited) {
         in(1)._print0(sb.append("(-"), visited);
diff --git a/chapter24/src/main/java/com/seaofnodes/simple/node/MinusNode.java b/chapter24/src/main/java/com/seaofnodes/simple/node/MinusNode.java
index 3ab74625..e87d8dd4 100644
--- a/chapter24/src/main/java/com/seaofnodes/simple/node/MinusNode.java
+++ b/chapter24/src/main/java/com/seaofnodes/simple/node/MinusNode.java
@@ -10,8 +10,6 @@ public class MinusNode extends Node {
 
     @Override public String label() { return "Minus"; }
 
-    @Override public String glabel() { return "-"; }
-
     @Override
     public StringBuilder _print1(StringBuilder sb, BitSet visited) {
         in(1)._print0(sb.append("(-"), visited);
diff --git a/chapter24/src/main/java/com/seaofnodes/simple/node/NewNode.java b/chapter24/src/main/java/com/seaofnodes/simple/node/NewNode.java
index 9310aa38..1a15439e 100644
--- a/chapter24/src/main/java/com/seaofnodes/simple/node/NewNode.java
+++ b/chapter24/src/main/java/com/seaofnodes/simple/node/NewNode.java
@@ -35,11 +35,7 @@ public class NewNode extends Node implements MultiNode {
 
     public Node mem (int idx) { return in(idx+2); }
 
-    @Override public String label() { return "new_"+glabel(); }
-    @Override public String glabel() {
-        return _ptr._obj.isAry() ? "ary_"+_ptr._obj._fields[1]._t.str() : _ptr._obj.str();
-    }
-
+    @Override public String label() { return "new_"+(_ptr._obj.isAry() ? "ary_"+_ptr._obj._fields[1]._t.str() : _ptr._obj.str()); }
     @Override
     public StringBuilder _print1(StringBuilder sb, BitSet visited) {
         sb.append("new ");
diff --git a/chapter24/src/main/java/com/seaofnodes/simple/node/Node.java b/chapter24/src/main/java/com/seaofnodes/simple/node/Node.java
index f45a1aa8..5583d3d6 100644
--- a/chapter24/src/main/java/com/seaofnodes/simple/node/Node.java
+++ b/chapter24/src/main/java/com/seaofnodes/simple/node/Node.java
@@ -6,7 +6,6 @@ import com.seaofnodes.simple.util.Ary;
 import com.seaofnodes.simple.util.Utils;
 import com.seaofnodes.simple.codegen.CodeGen;
 import com.seaofnodes.simple.print.IRPrinter;
-import com.seaofnodes.simple.print.JSViewer;
 import com.seaofnodes.simple.type.Type;
 import com.seaofnodes.simple.type.TypeFloat;
 import com.seaofnodes.simple.type.TypeInteger;
@@ -81,14 +80,12 @@ public abstract class Node implements Cloneable {
     // Easy reading label for debugger, e.g. "Add" or "Region" or "EQ"
     public abstract String label();
 
-    // Unique label for graph visualization, e.g. "Add12" or "Region30" or "EQ99"
+    // Unique label for debugging, e.g. "Add12" or "Region30" or "EQ99"
     public String uniqueName() {
-        // Get rid of $ as graphviz doesn't like it
-        String label = label().replaceAll("\\$", "");
-        return label + _nid;
+        return label() + _nid;
     }
 
-    // Graphical label, e.g. "+" or "Region" or "=="
+    // Operator symbol used by assembly/debug printing.
     public String glabel() { return label(); }
 
     // Extra fun stuff, for assembly printing.  Jump labels, parser locations,
@@ -379,13 +376,13 @@ public abstract class Node implements Cloneable {
      * Try to peephole at this node and return a better replacement Node.
      * Always returns some not-null Node (often this).
      */
-    public final Node peephole( ) {
-        if( _type==null )       // Brand-new node, never peeped before
-            JSViewer.show();
+    public final Node peephole() {
+        var obs = CodeGen.CODE._midAssert ? null : CodeGen.CODE._obs;
+        if( obs != null ) obs.before(this);
         Node n = peepholeOpt();
-        if( n!=null )           // Made progress?
-            JSViewer.show();    // Show again
-        return n==null ? this : deadCodeElim(n._nid >= _nid ? n.peephole() : n); // Cannot return null for no-progress
+        Node rez = n == null ? this : deadCodeElim(n._nid >= _nid ? n.peephole() : n);
+        if( obs != null ) obs.after(this, n == null ? null : rez, false);
+        return rez;
     }
 
     /**
@@ -548,6 +545,8 @@ public abstract class Node implements Cloneable {
     // retry the peephole.  Track a set of Nodes dependent on `this`, and
     // revisit them if `this` changes.
     Ary<Node> _deps;
+    public int nDeps() { return _deps == null ? 0 : _deps.size(); }
+    public Node dep(int idx) { return _deps.get(idx); }
 
     /**
      * Add a node to the list of dependencies.  Only add it if it's not an input
@@ -558,6 +557,8 @@ public abstract class Node implements Cloneable {
         // Running peepholes during the big assert cannot have side effects
         // like adding dependencies.
         if( CODE._midAssert ) return dep;
+        var obs = CodeGen.CODE._midAssert ? null : CodeGen.CODE._obs;
+        if( obs != null ) obs.dep(this, dep);
         if( dep._deps==null ) dep._deps = new Ary<>(Node.class);
         if( dep._deps   .find(this) != -1 ) return dep; // Already on list
         if( dep._inputs .find(this) != -1 ) return dep; // No need for deps on immediate neighbors
diff --git a/chapter24/src/main/java/com/seaofnodes/simple/node/NotNode.java b/chapter24/src/main/java/com/seaofnodes/simple/node/NotNode.java
index 4b80e61c..1cbd2402 100644
--- a/chapter24/src/main/java/com/seaofnodes/simple/node/NotNode.java
+++ b/chapter24/src/main/java/com/seaofnodes/simple/node/NotNode.java
@@ -9,8 +9,6 @@ public class NotNode extends Node {
 
     @Override public String label() { return "Not"; }
 
-    @Override public String glabel() { return "!"; }
-
     @Override
     public StringBuilder _print1(StringBuilder sb, BitSet visited) {
         in(1)._print0(sb.append("(!"), visited);
diff --git a/chapter24/src/main/java/com/seaofnodes/simple/node/OrNode.java b/chapter24/src/main/java/com/seaofnodes/simple/node/OrNode.java
index ac0d8454..6b48815d 100644
--- a/chapter24/src/main/java/com/seaofnodes/simple/node/OrNode.java
+++ b/chapter24/src/main/java/com/seaofnodes/simple/node/OrNode.java
@@ -9,9 +9,6 @@ public class OrNode extends ArithNode {
 
     @Override public String label() { return "Or"; }
     @Override public String op() { return "|"; }
-    @Override public String glabel() { return "|"; }
-
-
     @Override long doOp( long x, long y ) { return x | y; }
     @Override TypeInteger doOp(TypeInteger x, TypeInteger y) {
         return TypeInteger.BOT;
diff --git a/chapter24/src/main/java/com/seaofnodes/simple/node/ParmNode.java b/chapter24/src/main/java/com/seaofnodes/simple/node/ParmNode.java
index 880f936c..48d05e6b 100644
--- a/chapter24/src/main/java/com/seaofnodes/simple/node/ParmNode.java
+++ b/chapter24/src/main/java/com/seaofnodes/simple/node/ParmNode.java
@@ -18,8 +18,6 @@ public class ParmNode extends PhiNode {
 
     @Override public String label() { return MemOpNode.mlabel(_label); }
 
-    @Override public String glabel() { return _label; }
-
     public FunNode fun() { return (FunNode)in(0); }
 
     @Override
diff --git a/chapter24/src/main/java/com/seaofnodes/simple/node/PhiNode.java b/chapter24/src/main/java/com/seaofnodes/simple/node/PhiNode.java
index b2483218..81af208c 100644
--- a/chapter24/src/main/java/com/seaofnodes/simple/node/PhiNode.java
+++ b/chapter24/src/main/java/com/seaofnodes/simple/node/PhiNode.java
@@ -37,8 +37,6 @@ public class PhiNode extends Node {
 
     @Override public String label() { return "Phi_"+MemOpNode.mlabel(_label); }
 
-    @Override public String glabel() { return "&phi;_"+_label; }
-
     @Override
     public StringBuilder _print1(StringBuilder sb, BitSet visited) {
         if( !(region() instanceof RegionNode r) || r.inProgress() )
diff --git a/chapter24/src/main/java/com/seaofnodes/simple/node/RoundF32Node.java b/chapter24/src/main/java/com/seaofnodes/simple/node/RoundF32Node.java
index 7936086d..2ad034d6 100644
--- a/chapter24/src/main/java/com/seaofnodes/simple/node/RoundF32Node.java
+++ b/chapter24/src/main/java/com/seaofnodes/simple/node/RoundF32Node.java
@@ -10,8 +10,6 @@ public class RoundF32Node extends Node {
 
     @Override public String label() { return "RoundF32"; }
 
-    @Override public String glabel() { return "(f32)"; }
-
     @Override
     public StringBuilder _print1(StringBuilder sb, BitSet visited) {
         return in(1)._print0(sb.append("((f32)"), visited).append(")");
diff --git a/chapter24/src/main/java/com/seaofnodes/simple/node/SarNode.java b/chapter24/src/main/java/com/seaofnodes/simple/node/SarNode.java
index ee15fa65..6b8969e3 100644
--- a/chapter24/src/main/java/com/seaofnodes/simple/node/SarNode.java
+++ b/chapter24/src/main/java/com/seaofnodes/simple/node/SarNode.java
@@ -9,8 +9,6 @@ public class SarNode extends ArithNode {
 
     @Override public String label() { return "Sar"; }
     @Override public String op() { return ">>"; }
-    @Override public String glabel() { return "&gt;&gt;"; }
-
     @Override long doOp( long x, long y ) { return x >> y; }
     @Override TypeInteger doOp( TypeInteger x, TypeInteger y ) {
         if( y.isConstant() ) {
diff --git a/chapter24/src/main/java/com/seaofnodes/simple/node/ShlNode.java b/chapter24/src/main/java/com/seaofnodes/simple/node/ShlNode.java
index 2557bf6b..60c91fc9 100644
--- a/chapter24/src/main/java/com/seaofnodes/simple/node/ShlNode.java
+++ b/chapter24/src/main/java/com/seaofnodes/simple/node/ShlNode.java
@@ -9,8 +9,6 @@ public class ShlNode extends ArithNode {
 
     @Override public String label() { return "Shl"; }
     @Override public String op() { return "<<"; }
-    @Override public String glabel() { return "&lt;&lt;"; }
-
     @Override long doOp( long x, long y ) { return x << y; }
     @Override TypeInteger doOp( TypeInteger x, TypeInteger y ) {
         if( x == TypeInteger.ZERO )
diff --git a/chapter24/src/main/java/com/seaofnodes/simple/node/ShrNode.java b/chapter24/src/main/java/com/seaofnodes/simple/node/ShrNode.java
index 269f6b7f..81dae615 100644
--- a/chapter24/src/main/java/com/seaofnodes/simple/node/ShrNode.java
+++ b/chapter24/src/main/java/com/seaofnodes/simple/node/ShrNode.java
@@ -9,8 +9,6 @@ public class ShrNode extends ArithNode {
 
     @Override public String label() { return "Shr"; }
     @Override public String op() { return ">>>"; }
-    @Override public String glabel() { return "&gt;&gt;&gt;"; }
-
     @Override long doOp( long x, long y ) { return x >>> y; }
     @Override TypeInteger doOp( TypeInteger x, TypeInteger y ) {
         return x == TypeInteger.ZERO ? x : TypeInteger.BOT;
diff --git a/chapter24/src/main/java/com/seaofnodes/simple/node/StoreNode.java b/chapter24/src/main/java/com/seaofnodes/simple/node/StoreNode.java
index 8e33512a..09257730 100644
--- a/chapter24/src/main/java/com/seaofnodes/simple/node/StoreNode.java
+++ b/chapter24/src/main/java/com/seaofnodes/simple/node/StoreNode.java
@@ -24,10 +24,8 @@ public class StoreNode extends MemOpNode {
         _init = init;
     }
 
-    // GraphVis DOT code and debugger labels
+    // Debugger label
     @Override public String  label() { return "st_"+mlabel(); }
-    // GraphVis node-internal labels
-    @Override public String glabel() { return "." +_name+"="; }
     @Override public boolean isMem() { return true; }
 
     public Node val() { return in(4); }
diff --git a/chapter24/src/main/java/com/seaofnodes/simple/node/ToFloatNode.java b/chapter24/src/main/java/com/seaofnodes/simple/node/ToFloatNode.java
index e02183a0..5734bcbc 100644
--- a/chapter24/src/main/java/com/seaofnodes/simple/node/ToFloatNode.java
+++ b/chapter24/src/main/java/com/seaofnodes/simple/node/ToFloatNode.java
@@ -11,8 +11,6 @@ public class ToFloatNode extends Node {
 
     @Override public String label() { return "ToFloat"; }
 
-    @Override public String glabel() { return "(flt)"; }
-
     @Override
     public StringBuilder _print1(StringBuilder sb, BitSet visited) {
         return in(1)._print0(sb.append("(flt)"), visited);
diff --git a/chapter24/src/main/java/com/seaofnodes/simple/node/XorNode.java b/chapter24/src/main/java/com/seaofnodes/simple/node/XorNode.java
index fdb4863e..cff1706a 100644
--- a/chapter24/src/main/java/com/seaofnodes/simple/node/XorNode.java
+++ b/chapter24/src/main/java/com/seaofnodes/simple/node/XorNode.java
@@ -9,8 +9,6 @@ public class XorNode extends ArithNode {
 
     @Override public String label() { return "Xor"; }
     @Override public String op() { return "^"; }
-    @Override public String glabel() { return "^"; }
-
     @Override long doOp( long x, long y ) { return x ^ y; }
     @Override TypeInteger doOp( TypeInteger x, TypeInteger y ) {
         return TypeInteger.BOT;
diff --git a/chapter24/src/main/java/com/seaofnodes/simple/print/GraphVisualizer.java b/chapter24/src/main/java/com/seaofnodes/simple/print/GraphVisualizer.java
deleted file mode 100644
index 20c8439a..00000000
--- a/chapter24/src/main/java/com/seaofnodes/simple/print/GraphVisualizer.java
+++ /dev/null
@@ -1,287 +0,0 @@
-package com.seaofnodes.simple.print;
-
-import com.seaofnodes.simple.Parser;
-import com.seaofnodes.simple.node.*;
-import java.util.*;
-import static com.seaofnodes.simple.util.Utils.TODO;
-
-/**
- * Simple visualizer that outputs GraphViz dot format.
- * The dot output must be saved to a file and run manually via dot to generate the SVG output.
- * Currently, this is done manually.
- */
-public class GraphVisualizer {
-
-    /**
-     * If set to true we put the control nodes in a separate cluster from
-     * data nodes.
-     */
-    boolean _separateControlCluster = false;
-
-    public GraphVisualizer(boolean separateControlCluster) { this._separateControlCluster = separateControlCluster; }
-    public GraphVisualizer() { this(false); }
-
-    public String generateDotOutput(Parser parse) { return generateDotOutput(parse._code._stop,parse._scope,parse._xScopes); }
-    public String generateDotOutput(StopNode stop, Node scope, Stack<ScopeNode> xScopes) {
-
-        // Since the graph has cycles, we need to create a flat list of all the
-        // nodes in the graph.
-        Collection<Node> all = findAll(xScopes, stop, scope);
-        StringBuilder sb = new StringBuilder();
-        sb.append("digraph chapter18 {\n");
-        sb.append("/*\n");
-        sb.append(stop._src);
-        sb.append("\n*/\n");
-
-        // To keep the Scopes below the graph and pointing up into the graph we
-        // need to group the Nodes in a subgraph cluster, and the scopes into a
-        // different subgraph cluster.  THEN we can draw edges between the
-        // scopes and nodes.  If we try to cross subgraph cluster borders while
-        // still making the subgraphs DOT gets confused.
-        sb.append("\trankdir=BT;\n"); // Force Nodes before Scopes
-
-        // CNC - turned off Apr/8/2024, gives more flex in the layout and
-        // removes some of the more ludicrous layout choices.
-        // Preserve node input order
-        //sb.append("\tordering=\"in\";\n");
-
-        // Merge multiple edges hitting the same node.  Makes common shared
-        // nodes much prettier to look at.
-        sb.append("\tconcentrate=\"true\";\n");
-
-        // Force nested scopes to order
-        sb.append("\tcompound=\"true\";\n");
-
-        // Just the Nodes first, in a cluster no edges
-        nodes(sb, all);
-
-        // Now the scopes, in a cluster no edges
-        if( xScopes != null )
-            for( ScopeNode xscope : xScopes )
-                if( !xscope.isDead() )
-                    scope( sb, xscope );
-
-        // Walk the Node edges
-        nodeEdges(sb, all);
-
-        // Walk the active Scope edges
-        if( xScopes != null )
-            for( ScopeNode xscope : xScopes )
-                if( !xscope.isDead() )
-                    scopeEdges( sb, xscope );
-
-        sb.append("}\n");
-        return sb.toString();
-    }
-
-    private void nodesByCluster(StringBuilder sb, boolean doCtrl, Collection<Node> all) {
-        if (!_separateControlCluster && doCtrl) // all nodes in 1 cluster
-            return;
-        // Just the Nodes first, in a cluster no edges
-        sb.append(doCtrl ? "\tsubgraph cluster_Controls {\n" : "\tsubgraph cluster_Nodes {\n"); // Magic "cluster_" in the subgraph name
-        for (Node n : all) {
-            if (n instanceof ProjNode || n instanceof CProjNode || n instanceof MemMergeNode || n==Parser.XCTRL)
-                continue; // Do not emit, rolled into MultiNode or Scope cluster already
-            if( _separateControlCluster &&  doCtrl && !(n instanceof CFGNode) ) continue;
-            if( _separateControlCluster && !doCtrl &&  (n instanceof CFGNode) ) continue;
-            sb.append("\t\t").append(n.uniqueName()).append(" [ ");
-            String lab = n.glabel();
-            if (n instanceof MultiNode) {
-                // Make a box with the MultiNode on top, and all the projections on the bottom
-                sb.append("shape=plaintext label=<\n");
-                sb.append("\t\t\t<TABLE BORDER=\"0\" CELLBORDER=\"1\" CELLSPACING=\"0\" CELLPADDING=\"4\">\n");
-                sb.append("\t\t\t<TR><TD BGCOLOR=\"yellow\">").append(lab).append("</TD></TR>\n");
-                sb.append("\t\t\t<TR>");
-                boolean doProjTable = false;
-                n._outputs.sort((x,y) -> x instanceof ProjNode xp && y instanceof ProjNode yp ? (xp._idx - yp._idx) : (x._nid - y._nid));
-                for (Node use : n._outputs) {
-                    if (use instanceof ProjNode proj) {
-                        if (!doProjTable) {
-                            doProjTable = true;
-                            sb.append("<TD>").append("\n");
-                            sb.append("\t\t\t\t<TABLE BORDER=\"0\" CELLBORDER=\"1\" CELLSPACING=\"0\">").append("\n");
-                            sb.append("\t\t\t\t<TR>");
-                        }
-                        sb.append("<TD PORT=\"p").append(proj._idx).append("\">").append(proj.glabel()).append("</TD>");
-                    }
-                    if (use instanceof CProjNode proj) {
-                        if (!doProjTable) {
-                            doProjTable = true;
-                            sb.append("<TD>").append("\n");
-                            sb.append("\t\t\t\t<TABLE BORDER=\"0\" CELLBORDER=\"1\" CELLSPACING=\"0\">").append("\n");
-                            sb.append("\t\t\t\t<TR>");
-                        }
-                        sb.append("<TD PORT=\"p").append(proj._idx).append("\" BGCOLOR=\"yellow\">").append(proj.glabel()).append("</TD>");
-                    }
-                }
-                if (doProjTable) {
-                    sb.append("</TR>").append("\n");
-                    sb.append("\t\t\t\t</TABLE>").append("\n");
-                    sb.append("\t\t\t</TD>");
-                }
-                sb.append("</TR>\n");
-                sb.append("\t\t\t</TABLE>>\n\t\t");
-
-            } else {
-                // control nodes have box shape
-                // other nodes are ellipses, i.e. default shape
-                if( n instanceof CFGNode ) sb.append("shape=box style=filled fillcolor=yellow ");
-                else if (n instanceof PhiNode) sb.append("style=filled fillcolor=lightyellow ");
-                sb.append("label=\"").append(lab).append("\" ");
-            }
-            sb.append("];\n");
-        }
-        if (!_separateControlCluster) {
-            // Force Region & Phis to line up
-            for (Node n : all) {
-                if (n instanceof RegionNode region) {
-                    sb.append("\t\t{ rank=same; ");
-                    sb.append(region.uniqueName()).append(";");
-                    for (Node phi : region._outputs)
-                        if (phi instanceof PhiNode) sb.append(phi.uniqueName()).append(";");
-                    sb.append("}\n");
-                }
-            }
-        }
-        sb.append("\t}\n");     // End Node cluster
-    }
-
-    private void nodes(StringBuilder sb, Collection<Node> all) {
-        nodesByCluster(sb, true, all);
-        nodesByCluster(sb, false, all);
-    }
-
-    // Build a nested scope display, walking the _prev edge
-    private void scope( StringBuilder sb, ScopeNode scope ) {
-        sb.append("\tnode [shape=plaintext];\n");
-        int last = scope.nIns();
-        int max = scope.depth();
-        for( int i = 0; i < max; i++ ) {
-            int level = max-i-1;
-            String scopeName = makeScopeName(scope, level);
-            sb.append("\tsubgraph cluster_").append(scopeName).append(" {\n"); // Magic "cluster_" in the subgraph name
-            // Special for memory ScopeMinNode
-            if( level==0 ) {
-                MemMergeNode n = scope.mem();
-                sb.append("\t\t").append(n.uniqueName()).append(" [label=\"").append(n.glabel()).append("\"];\n");
-            }
-            sb.append("\t\t").append(scopeName).append(" [label=<\n");
-            sb.append("\t\t\t<TABLE BORDER=\"0\" CELLBORDER=\"1\" CELLSPACING=\"0\">\n");
-            // Add the scope level
-            sb.append("\t\t\t<TR><TD BGCOLOR=\"cyan\">").append(level).append("</TD>");
-            int lexStart = scope._kinds.at(level)._lexSize;
-            for( int j=lexStart; j<last; j++ ) {
-                var v = scope._vars.at(j);
-                sb.append("<TD PORT=\"").append(makePortName(scopeName, v._name)).append("\">").append(v._name).append("</TD>");
-            }
-            last = lexStart;
-            sb.append("</TR>\n");
-            sb.append("\t\t\t</TABLE>>];\n");
-        }
-        // Scope clusters nest, so the graphics shows the nested scopes, so
-        // they are not closed as they are printed; so they just keep nesting.
-        // We close them all at once here.
-        sb.append( "\t}\n".repeat( max ) ); // End all Scope clusters
-    }
-
-    private String makeScopeName(ScopeNode sn, int level) { return sn.uniqueName() + "_" + level; }
-    private String makePortName(String scopeName, String varName) { return scopeName + "_" + varName; }
-
-    // Walk the node edges
-    private void nodeEdges(StringBuilder sb, Collection<Node> all) {
-        // All them edge labels
-        sb.append("\tedge [ fontname=Helvetica, fontsize=8 ];\n");
-        for( Node n : all ) {
-            // Do not display the Constant->Start edge;
-            // ProjNodes handled by Multi;
-            // ScopeNodes are done separately
-            if( n instanceof ConstantNode || n instanceof ProjNode || n instanceof CProjNode || n instanceof ScopeNode || n==Parser.XCTRL )
-                continue;
-            for( int i=0; i<n.nIns(); i++ ) {
-                Node def = n.in(i);
-                if( n instanceof PhiNode && def instanceof RegionNode ) {
-                    // Draw a dotted use->def edge from Phi to Region.
-                    sb.append('\t').append(n.uniqueName());
-                    sb.append(" -> ");
-                    sb.append(def.uniqueName());
-                    sb.append(" [style=dotted taillabel=").append(i).append("];\n");
-                } else if( def != null ) {
-                    // Most edges land here use->def
-                    sb.append('\t').append(n.uniqueName()).append(" -> ");
-                    if( def instanceof CProjNode proj ) {
-                        String mname = proj.ctrl().uniqueName();
-                        sb.append(mname).append(":p").append(proj._idx);
-                    } else if( def instanceof ProjNode proj ) {
-                        String mname = proj.in(0).uniqueName();
-                        sb.append(mname).append(":p").append(proj._idx);
-                    } else sb.append(def.uniqueName());
-                    // Number edges, so we can see how they track
-                    sb.append("[taillabel=").append(i);
-                    // The edge from New to ctrl is just for anchoring the New
-                    if ( n instanceof NewNode )
-                        sb.append(" color=green");
-                    // control edges are colored red
-                    else if( def instanceof CFGNode )
-                        sb.append(" color=red");
-                    else if( def.isMem() )
-                        sb.append(" color=blue");
-                    // Backedges do not add a ranking constraint
-                    if( i==2 && (n instanceof PhiNode || n instanceof LoopNode) )
-                        sb.append(" constraint=false");
-                    sb.append("];\n");
-                }
-            }
-        }
-    }
-
-    // Walk the scope edges
-    private void scopeEdges( StringBuilder sb, ScopeNode scope ) {
-        sb.append("\tedge [style=dashed color=cornflowerblue];\n");
-        int level=0;
-        for( var v : scope._vars ) {
-            Node def = scope.in(v._idx);
-            while( def instanceof ScopeNode lazy )
-                def = lazy.in(v._idx);
-            if( def==null ) continue;
-            while( level < scope.depth() && v._idx >= scope._kinds.at(level)._lexSize )
-                level++;
-            String scopeName = makeScopeName(scope, level-1);
-            sb.append("\t")
-                .append(scopeName).append(":")
-                .append('"').append(makePortName(scopeName, v._name)).append('"') // wrap port name with quotes because $ctrl is not valid unquoted
-                .append(" -> ");
-            if( def instanceof CProjNode proj ) {
-                sb.append(def.in(0).uniqueName()).append(":p").append(proj._idx);
-            } else if( def instanceof ProjNode proj ) {
-                sb.append(def.in(0).uniqueName()).append(":p").append(proj._idx);
-            } else sb.append(def.uniqueName());
-            sb.append(";\n");
-        }
-    }
-
-    /**
-     * Finds all nodes in the graph.
-     */
-    public static Collection<Node> findAll(Stack<ScopeNode> ss, Node... ns) {
-        final HashMap<Integer, Node> all = new HashMap<>();
-        for( Node n : ns )
-            walk(all, n);
-        if( ss != null )
-            for( Node n : ss )
-                walk(all, n);
-        return all.values();
-    }
-
-    /**
-     * Walk a subgraph and populate distinct nodes in the all list.
-     */
-    private static void walk(HashMap<Integer,Node> all, Node n) {
-        if(n == null ) return;
-        if (all.get(n._nid) != null) return; // Been there, done that
-        all.put(n._nid, n);
-        for (Node c : n._inputs)
-            walk(all, c);
-        for( Node c : n._outputs )
-            walk(all, c);
-    }
-}
diff --git a/chapter24/src/main/java/com/seaofnodes/simple/print/JSViewer.java b/chapter24/src/main/java/com/seaofnodes/simple/print/JSViewer.java
deleted file mode 100644
index f4f72a3b..00000000
--- a/chapter24/src/main/java/com/seaofnodes/simple/print/JSViewer.java
+++ /dev/null
@@ -1,421 +0,0 @@
-package com.seaofnodes.simple.print;
-
-import com.seaofnodes.simple.codegen.CodeGen;
-import com.seaofnodes.simple.node.*;
-import com.seaofnodes.simple.type.*;
-import com.seaofnodes.simple.util.SB;
-import com.seaofnodes.simple.util.Utils;
-import java.io.IOException;
-import java.nio.file.Paths;
-import java.nio.file.Files;
-import java.nio.file.Path;
-import java.net.URI;
-import java.util.Collection;
-import java.util.Stack;
-import static com.seaofnodes.simple.codegen.CodeGen.CODE;
-
-public class JSViewer implements AutoCloseable {
-    // Display programs in an endless loop
-    public static void main( String[] args ) throws Exception {
-        try(var js = new JSViewer()) {
-            js.run();
-        }
-    }
-
-    static boolean SHOW;
-
-    // WebSocket to the browser for display
-    static SimpleWebSocket SERVER;
-
-    static int N;               // Dot frames
-
-    JSViewer() throws Exception {
-        // Launch server; handshake
-        SERVER = new SimpleWebSocket(viewerURI(),12345);
-    }
-
-    // The browser application is shared by all chapters. Search upwards so
-    // chapter, repository-root, and linearized checkouts use the same assets.
-    static URI viewerURI() throws IOException {
-        String url = System.getProperty("simple.graph.url");
-        if( url != null ) return URI.create(url);
-        for( Path dir = Paths.get("").toAbsolutePath(); dir != null; dir = dir.getParent() ) {
-            Path page = dir.resolve("graph/web/index.html");
-            if( Files.isRegularFile(page) ) return page.toUri();
-        }
-        throw new IOException("Cannot find graph/web/index.html; run inside the Simple checkout "
-                              + "or set -Dsimple.graph.url=<viewer URL>");
-    }
-
-    void run( ) throws Exception {
-        SERVER.put("!");
-        while( true ) {
-            String src = SERVER.get();
-            switch( src ) {
-            case null: return;
-            case "null": return;
-            case "+": break;    // Client requests more frames, but we send them all anyway
-            default:
-                System.out.println(src);
-                try {
-                    N=0;
-                    // Use parser scope, xscope when building views
-                    CodeGen code = new CodeGen(src);
-                    SHOW = true;
-                    show();
-                    // Parse program, generating views at every parse point
-                    code.parse();
-                    // No longer user parse internal state when building views
-                    code.opto();
-
-                    // Catch and ignore Parser errors
-                } catch(RuntimeException re) {
-                    System.err.println(re);
-                } finally {
-                    SHOW = false;
-                    SERVER.put("#"); // Final frame
-                }
-                break;
-            }
-        }
-    }
-
-    @Override public void close() throws IOException {
-        SERVER.close();
-        SERVER=null;
-    }
-
-    public static void show() { if( SERVER!=null && SHOW ) _show(); }
-    private static void _show() {
-        // Skip util we at least get the Parse object made
-        if( CODE._phase==null || CODE._phase.ordinal() < CodeGen.Phase.Parse.ordinal() )
-            return;
-        boolean midParse = CODE._phase == CodeGen.Phase.Parse;
-        Stack<ScopeNode> xScopes = midParse ? CODE.P._xScopes : null;
-
-        Collection<Node> all = GraphVisualizer.findAll(xScopes, CODE._stop, midParse ? CODE.P._scope: null);
-        SB sb = new SB();
-        sb.p("digraph view_").p(N++).p(" {\n").ii();
-        if( midParse )
-            sb.i().p("// POS: ").p(CODE.P.pos()).nl();
-
-        // To keep the Scopes below the graph and pointing up into the graph we
-        // need to group the Nodes in a subgraph cluster, and the scopes into a
-        // different subgraph cluster.  THEN we can draw edges between the
-        // scopes and nodes.  If we try to cross subgraph cluster borders while
-        // still making the subgraphs DOT gets confused.
-        sb.i().p("rankdir=BT;\n"); // Force Nodes before Scopes
-
-        // CNC - turned off Apr/8/2024, gives more flex in the layout and
-        // removes some of the more ludicrous layout choices.
-        // Preserve node input order
-        //sb.append("ordering=\"in\";\n");
-
-        // Merge multiple edges hitting the same node.  Makes common shared
-        // nodes much prettier to look at.
-        sb.i().p("concentrate=\"true\";\n");
-
-        // Force nested scopes to order
-        sb.i().p("compound=\"true\";\n");
-
-        // Just the Nodes first, in a cluster no edges
-        nodes(sb, all);
-
-        // Now the scopes, in a cluster no edges
-        if( midParse )
-            for( ScopeNode xscope : xScopes )
-                if( !xscope.isDead() )
-                    scope( sb, xscope );
-
-        // Walk the Node edges
-        nodeEdges(sb, midParse && !xScopes.empty() ? xScopes.peek() : null, all);
-
-        // Walk the active Scope edges
-        if( midParse )
-            for( ScopeNode xscope : xScopes )
-                if( !xscope.isDead() )
-                    scopeEdges( sb, xscope );
-
-
-        sb.p("}\n").di();
-        // Tell client another DOT frame
-        String dot = sb.toString();
-        System.out.println(dot);
-        try {
-            SERVER.put(dot);
-        } catch( IOException ioe ) {
-            try { SERVER.close();} catch( IOException ignored ){}
-        }
-    }
-
-
-    private static void nodes(SB sb, Collection<Node> all) {
-        // Just the Nodes first, in a cluster no edges
-        sb.i().p("subgraph cluster_Nodes {\n").ii(); // Magic "cluster_" in the subgraph name
-        for( Node n : all ) {
-            if( n instanceof ProjNode || n instanceof CProjNode || n instanceof MemMergeNode )
-                continue; // Do not emit, rolled into MultiNode or Scope cluster already
-            sb.i().p(n.uniqueName()).p(" [ ");
-            if( n instanceof MultiNode && !(n instanceof StartNode) ) {
-                // Make a box with the MultiNode on top, and all the projections on the bottom
-                sb.    p("shape=plaintext label=<\n").ii();
-                sb.i().p("<TABLE BORDER=\"0\" CELLBORDER=\"1\" CELLSPACING=\"0\" CELLPADDING=\"4\">\n");
-                // Row over single cell for node label
-                cell(sb.i().p("<TR>"), n.glabel(), n, null).p("</TR>\n");
-                // Row over single cell, for nested table
-                sb.i().p("<TR><TD>\n").ii();
-                sb.i().p("<TABLE BORDER=\"0\" CELLBORDER=\"1\" CELLSPACING=\"0\">").p("\n");
-                sb.i().p("<TR>");
-                n._outputs.sort((x,y) -> x instanceof ProjNode xp && y instanceof ProjNode yp ? (xp._idx - yp._idx) : ((x==null ? 99999 : x._nid) - (y==null ? 99999 : y._nid)));
-                boolean empty_row=true;
-                for( Node use : n._outputs ) {
-                    int idx = idx(n);
-                    if( idx != -1 ) {
-                        cell(sb,use.glabel(),use,"p"+idx);
-                        empty_row=false;
-                    }
-                }
-                // At least one cell on row
-                if( empty_row )  sb.p("<TD></TD>");
-                sb.    p("</TR>").p("\n");
-                sb.i().p("</TABLE>").p("\n").di();
-                sb.i().p("</TD></TR>\n");
-                sb.i().p("</TABLE>>\n").di();
-                sb.i().p("];\n");
-
-            } else {
-                // control nodes have box shape
-                // other nodes are ellipses, i.e. default shape
-                //else if (n instanceof PhiNode) sb.p("style=filled fillcolor=lightyellow ");
-                node(sb,n.glabel(),n);
-                sb.p("];\n");
-            }
-        }
-        // Force Region & Phis to line up
-        for (Node n : all) {
-            if (n instanceof RegionNode region) {
-                sb.i().p("{ rank=same; ");
-                sb.p(region.uniqueName()).p(";");
-                for (Node phi : region._outputs)
-                    if (phi instanceof PhiNode) sb.p(phi.uniqueName()).p(";");
-                sb.p("}\n");
-            }
-        }
-        sb.di().i().p("}").nl();     // End Node cluster
-    }
-
-    // Build a nested scope display, walking the _prev edge
-    private static void scope( SB sb, ScopeNode scope ) {
-        sb.i().p("node [shape=plaintext];\n");
-        int last = scope.nIns();
-        int max = scope.depth()+1; // One more than lexsize
-        for( int i = 0; i < max; i++ ) {
-            int level = max-i-1;
-            String scopeName = makeScopeName(scope, level);
-            sb.i().p("subgraph cluster_").p(scopeName).p(" {\n").ii(); // Magic "cluster_" in the subgraph name
-            sb.i().p(scopeName).p(" [label=<\n").ii();
-            sb.i().p("<TABLE BORDER=\"0\" CELLBORDER=\"1\" CELLSPACING=\"0\">\n");
-            int lexStart = level==0 ? 0 : scope._kinds.at(level-1)._lexSize;
-
-            // Special for memory ScopeMinNode
-            MemMergeNode n = scope.nIns()>1 ? scope.mem() : null;
-            if( level==0 && n!=null && n.nIns()>2 ) {
-                sb.i().p("<TR>");
-                for( int m=2; m<n.nIns(); m++ )
-                    cell(sb,"#"+m,n.alias(m),"m"+m);
-                sb.p("</TR>\n"); // End scope level
-            }
-
-            // Scope variables, empty if none
-            if( lexStart<last ) {
-                sb.i().p("<TR>\n");
-                for( int j=lexStart; j<last; j++ ) {
-                    if( scope.in(j)==null ) continue;
-                    var v = scope._vars.at(j);
-                    cell(sb.i(),v._name,scope.in(j),makePortName(scopeName, v._name)).nl();
-                }
-                last = lexStart;
-                sb.i().p("</TR>\n");
-            }
-            sb.i().p("</TABLE>>];\n").di();
-            // Scope label
-            sb.i().p(scopeName).p("A [label=\"").p(level).p("\" shape=doublecircle style=filled fillcolor=aqua fontsize=10 margin=0 width=0.2 ];\n");
-        }
-        // Scope clusters nest, so the graphics shows the nested scopes, so
-        // they are not closed as they are printed; so they just keep nesting.
-        // We close them all at once here.
-        for( int i=0; i<max; i++ )
-            sb.di().i().p("}\n");
-    }
-
-    // Append a cell, with color
-    private static SB cell(SB sb, String text, Node n, String port) {
-        sb.p("<TD");
-        String color = color(n);
-        sb.p(" BGCOLOR=\"").p(color).p("\"");
-        if( port!=null )  sb.p(" PORT=\"").p(port).p("\"");
-        return colorcell(sb.p(">"),text,n,dark(color)).p("</TD>");
-    }
-    private static SB node(SB sb, String text, Node n) {
-        String color = color(n);
-        sb.p("style=filled fillcolor=").p(color).p(" ");
-        String shape = switch( n ) {
-        case FunNode fun -> "shape=box peripheries=2";
-        case CFGNode cfg -> "shape=box";
-        default -> "";
-        };
-        sb.p(shape).p(" ");
-        return colorcell(sb.p("label=<"),text,n,dark(color)).p(">");
-    }
-
-    private static String color(Node n) {
-        return switch( n ) {
-        case CFGNode cfg  -> "yellow";
-        case NewNode nnn  -> "lightgreen";
-        case StructNode s -> "lightgreen";
-        default -> typeColor(n._type);
-        };
-    }
-    private static String typeColor(Type t) {
-        return t==null ? "white" : switch( t ) {
-        case TypeMem    mem -> "blue";
-        case TypeMemPtr tmp -> "green";
-        case TypeFunPtr tfp -> "orange";
-        case TypeRPC    rpc -> "antiquewhite";
-        case TypeInteger ti -> "lightblue";
-        case TypeFloat   tf -> "aqua";
-        case Type tn -> tn==Type.NIL ? "lightgray" : "red";
-        };
-    }
-    private static final String[] DARKS = new String[]{"blue","green","black"};
-    private static boolean dark(String color) { return Utils.find(DARKS,color) != -1; }
-
-
-
-    // Called with an open div
-    private static SB colorcell(SB sb, String text, Node n, boolean dark) {
-        if( dark ) sb.p("<font color=\"white\">");
-        sb.p(text);
-        if( n._type!=null ) {
-            sb.p("<br /><font point-size=\"10\">");
-            n._type.gprint(sb);
-            sb.p("</font>");
-        }
-        if( dark ) sb.p("</font>");
-        return sb;
-    }
-
-
-    private static String makeScopeName(ScopeNode sn, int level) { return sn.uniqueName() + "_" + level; }
-    private static String makePortName(String scopeName, String varName) { return scopeName + "_" + varName; }
-
-    // Walk the node edges
-    private static void nodeEdges(SB sb, ScopeNode scope, Collection<Node> all) {
-        // All them edge labels
-        String scopeName = scope!=null ? makeScopeName(scope, 0) : null;
-        sb.i().p("edge [ fontname=Helvetica, fontsize=8 ];\n");
-        for( Node n : all ) {
-            // Do not display the Constant->Start edge;
-            if( n instanceof ConstantNode ||
-                n instanceof XCtrlNode ||
-                // ProjNodes handled by Multi;
-                n instanceof ProjNode ||
-                n instanceof CProjNode ||
-                // ScopeNodes are done separately
-                n instanceof ScopeNode ||
-                n instanceof MemMergeNode
-                )
-                continue;
-            if( n.isDead() )
-                throw Utils.TODO();
-            // Normal edges
-            for( int i=0; i<n.nIns(); i++ ) {
-                Node def = n.in(i);
-                if( def==null ) continue;
-                sb.i().p(n.uniqueName()).p(" -> ");
-                if( n instanceof PhiNode && def instanceof RegionNode ) {
-                    // Draw a dotted use->def edge from Phi to Region.
-                    sb.p(def.uniqueName());
-                    sb.p(" [style=dotted taillabel=").p(i).p("];\n");
-                } else {
-                    // Most edges land here use->def
-                    if( def instanceof CProjNode proj ) {
-                        String mname = proj.ctrl().uniqueName();
-                        sb.p(mname).p(":p").p(proj._idx);
-                    } else if( def instanceof ProjNode proj ) {
-                        String mname = proj.in(0).uniqueName();
-                        sb.p(mname).p(":p").p(proj._idx);
-                    } else sb.p(def.uniqueName());
-                    // Number edges, so we can see how they track
-                    sb.p("[taillabel=").p(i);
-                    // Color the edge
-                    nodeEdgeColor(sb,def._type);
-                    // Backedges do not add a ranking constraint
-                    if( i==2 && (n instanceof PhiNode || n instanceof LoopNode) )
-                        sb.p(" constraint=false");
-                    sb.p("];\n");
-                }
-            }
-
-            // Bonus edge if hooked by parser
-            if( (n.iskeep() || n.isUnused()) && scopeName != null ) {
-                sb.i().p(scopeName).p(" -> ").p(n.uniqueName()).p(" [ style=dashed color=grey];\n");
-            }
-            // Force functions above return
-            if( n instanceof ReturnNode ret && ret.inProgress() && !ret.fun().isDead() )
-                sb.i().p(ret.ctrl().uniqueName()).p(" -> ").p(ret.fun().uniqueName()).p("[style=invis]\n");
-        }
-    }
-
-    private static void nodeEdgeColor(SB sb, Type t) {
-        sb.p(" color=").p(typeColor(t));
-    }
-
-    // Walk the scope edges
-    private static void scopeEdges( SB sb, ScopeNode scope ) {
-        sb.i().p("edge [style=dashed color=cornflowerblue];\n");
-        int level=0;
-        for( var v : scope._vars ) {
-            if( v._idx==1 ) continue; // Memory done separately
-            Node def = scope.in(v._idx);
-            while( def instanceof ScopeNode lazy )
-                def = lazy.in(v._idx);
-            if( def==null ) continue;
-            while( level < scope.depth() && v._idx >= scope._kinds.at(level)._lexSize )
-                level++;
-            String scopeName = makeScopeName(scope, level);
-            sb.i()
-                .p(scopeName).p(":")
-                .p('"').p(makePortName(scopeName, v._name)).p('"') // wrap port name with quotes because $ctrl is not valid unquoted
-                .p(" -> ");
-            defPort(sb,def).p(";\n");
-        }
-
-        // Memory
-        if( scope.nIns()>1 ) {
-            MemMergeNode n = scope.mem();
-            for( int i=2; i<n.nIns(); i++ ) {
-                Node def = n.in(i);
-                while( def instanceof ScopeNode lazy )
-                    def = lazy.in(i);
-                if( def==null ) continue;
-                String scopeName = makeScopeName(scope, 0);
-                sb.i().p(scopeName).p(":m").p(i).p(" -> ");
-                defPort(sb,def).p(";\n");
-            }
-        }
-
-    }
-
-    // (C)Projection index or -1
-    private static int idx(Node n) {
-        return n instanceof ProjNode p ? p._idx : (n instanceof CProjNode cp ? cp._idx : -1);
-    }
-
-    private static SB defPort(SB sb, Node def) {
-        int idx = idx(def);
-        return idx != -1
-            ? sb.p(def.in(0).uniqueName()).p(":p").p(idx)
-            : sb.p(def.uniqueName());
-    }
-}
diff --git a/chapter24/src/main/java/com/seaofnodes/simple/print/SimpleGraphAdapter.java b/chapter24/src/main/java/com/seaofnodes/simple/print/SimpleGraphAdapter.java
new file mode 100644
index 00000000..bf8f4181
--- /dev/null
+++ b/chapter24/src/main/java/com/seaofnodes/simple/print/SimpleGraphAdapter.java
@@ -0,0 +1,64 @@
+package com.seaofnodes.simple.print;
+
+import com.seaofnodes.graph.GraphAdapter;
+import com.seaofnodes.graph.GraphSnapshot;
+import com.seaofnodes.graph.GraphSnapshot.*;
+import com.seaofnodes.simple.node.*;
+import com.seaofnodes.simple.node.Node;
+import com.seaofnodes.simple.type.TypeMem;
+import java.util.ArrayList;
+
+/** Chapter 24's view of the IR; browser, transport and layout are shared. */
+public class SimpleGraphAdapter extends GraphAdapter<Node> {
+    @Override protected boolean dead(Node n) { return n.isDead(); }
+    @Override protected int id(Node n) { return n._nid; }
+    @Override protected int nIns(Node n) { return n.nIns(); }
+    @Override protected Node in(Node n, int idx) { return n.in(idx); }
+    @Override protected int nOuts(Node n) { return n.nOuts(); }
+    @Override protected Node out(Node n, int idx) { return n.out(idx); }
+    @Override protected int nDeps(Node n) { return n.nDeps(); }
+    @Override protected Node dep(Node n, int idx) { return n.dep(idx); }
+
+    private ArrayList<Edge> edges(Node n) {
+        var edges = new ArrayList<Edge>();
+        for( int i = 0; i < n.nIns(); i++ ) {
+            String name = n instanceof ScopeNode scope && i < scope._vars.size()
+                ? scope._vars.get(i)._name : null;
+            edges.add(new Edge(i, ref(n.in(i)), role(n, i), name));
+        }
+        return edges;
+    }
+
+    @Override protected GraphSnapshot.Node desc(Node n) {
+        Projection proj = n instanceof ProjNode p ? new Projection(ref(n.in(0)), p._idx)
+            : n instanceof CProjNode p ? new Projection(ref(n.in(0)), p._idx) : null;
+        String label = n.label();
+        return new GraphSnapshot.Node(n._nid, label == null ? n.getClass().getSimpleName() : label,
+                                      n._type == null ? null : n._type.toString(), kind(n), edges(n), proj);
+    }
+
+    private Kind kind(Node n) {
+        if( n instanceof ScopeNode ) return Kind.SCOPE;
+        if( n instanceof FunNode ) return Kind.FUN;
+        if( n instanceof StartNode ) return Kind.CTRL;
+        if( n instanceof LoopNode ) return Kind.LOOP;
+        if( n instanceof RegionNode ) return Kind.REGION;
+        if( n instanceof PhiNode ) return Kind.PHI;
+        return n instanceof CFGNode ? Kind.CTRL : isMem(n) ? Kind.MEM : Kind.DATA;
+    }
+
+    private Role role(Node n, int i) {
+        if( n instanceof ScopeNode || n instanceof ConstantNode || n instanceof CtrlNode || n instanceof XCtrlNode ) return Role.ASSOC;
+        if( n instanceof PhiNode ) return i == 0 ? Role.ASSOC : isMem(n) ? Role.MEM : Role.DATA;
+        if( n instanceof ProjNode || n instanceof CProjNode )
+            return n instanceof CFGNode ? Role.CTRL : isMem(n) ? Role.MEM : Role.DATA;
+        if( n instanceof RegionNode && i == 0 ) return Role.ASSOC;
+        if( i == 0 || n instanceof RegionNode || n instanceof StopNode ) return Role.CTRL;
+        if( n instanceof MemMergeNode || i == 1 && (n instanceof MemOpNode || n instanceof ReturnNode || n instanceof CallNode) ) return Role.MEM;
+        Node def = n.in(i);
+        if( def != null && isMem(def) ) return Role.MEM;
+        return Role.DATA;
+    }
+
+    private boolean isMem(Node n) { return n.isMem() || n._type instanceof TypeMem; }
+}
diff --git a/chapter24/src/main/java/com/seaofnodes/simple/print/SimpleGraphObserver.java b/chapter24/src/main/java/com/seaofnodes/simple/print/SimpleGraphObserver.java
new file mode 100644
index 00000000..ee540508
--- /dev/null
+++ b/chapter24/src/main/java/com/seaofnodes/simple/print/SimpleGraphObserver.java
@@ -0,0 +1,35 @@
+package com.seaofnodes.simple.print;
+
+import com.seaofnodes.graph.GraphCapture;
+import com.seaofnodes.graph.GraphViewer;
+import com.seaofnodes.simple.codegen.CodeGen;
+import com.seaofnodes.simple.node.Node;
+import java.util.ArrayList;
+import java.io.IOException;
+
+/** Chapter 24's compilation context; capture and event bookkeeping are shared. */
+public class SimpleGraphObserver extends GraphCapture<Node> {
+    private CodeGen _code;
+    public SimpleGraphObserver() { super(new SimpleGraphAdapter()); }
+    public static void main(String[] args) throws IOException {
+        GraphViewer.run(new SimpleGraphObserver());
+    }
+    @Override protected void compile(String src) {
+        _code = new CodeGen(src);
+        _code._obs = this;
+        _code.parse().opto();
+    }
+    @Override protected String phase() { return _code._phase.name(); }
+    @Override protected int pos() { return _code._phase == CodeGen.Phase.Parse ? _code.P.pos() : -1; }
+    @Override protected void detach() {
+        if( _code != null ) _code._obs = null;
+        _code = null;
+    }
+    @Override protected void roots(ArrayList<Node> roots) {
+        roots.add(_code._stop);
+        if( _code._phase == CodeGen.Phase.Parse ) {
+            roots.add(_code.P._scope);
+            roots.addAll(_code.P._xScopes);
+        }
+    }
+}
diff --git a/chapter24/src/main/java/com/seaofnodes/simple/print/SimpleWebSocket.java b/chapter24/src/main/java/com/seaofnodes/simple/print/SimpleWebSocket.java
deleted file mode 100644
index d7fa8bf2..00000000
--- a/chapter24/src/main/java/com/seaofnodes/simple/print/SimpleWebSocket.java
+++ /dev/null
@@ -1,193 +0,0 @@
-package com.seaofnodes.simple.print;
-
-import com.seaofnodes.simple.util.Utils;
-import java.io.*;
-import java.net.ServerSocket;
-import java.net.Socket;
-import java.net.URI;
-import java.nio.charset.StandardCharsets;
-import java.security.MessageDigest;
-import java.security.NoSuchAlgorithmException;
-import java.util.Base64;
-import java.net.InetSocketAddress;
-import java.nio.file.Path;
-import com.sun.net.httpserver.HttpServer;
-import com.sun.net.httpserver.SimpleFileServer;
-
-// Why-Oh-Why is this needed?
-
-// Pass in a URI and a port.
-// Opens the client; client has to open a websocket at the given port.
-// Connects, handshakes.
-// Thereafter you can call get/put to swap frames with client.
-
-class SimpleWebSocket extends ServerSocket {
-    final  InputStream _in;
-    final OutputStream _out;
-    private HttpServer _http;
-    private Socket _client;
-
-    SimpleWebSocket(URI uri, int port) throws IOException, NoSuchAlgorithmException {
-        super(port);
-        try {
-            // Use an ordinary web URL; desktop dispatch of file: URLs can silently
-            // raise the browser without opening the page.
-            if( "file".equals(uri.getScheme()) ) {
-                Path page = Path.of(uri);
-                _http = SimpleFileServer.createFileServer(
-                    new InetSocketAddress("127.0.0.1",0), page.getParent(),
-                    SimpleFileServer.OutputLevel.NONE);
-                _http.start();
-                uri = URI.create("http://127.0.0.1:" + _http.getAddress().getPort()
-                                 + "/" + page.getFileName());
-            }
-            // Print the address even if the desktop silently fails to open a tab.
-            System.out.println("Graph viewer: " + uri);
-            if( Boolean.parseBoolean(System.getProperty("simple.graph.open", "true")) )
-                java.awt.Desktop.getDesktop().browse(uri);
-            // Look for client; get in/out streams
-            Socket sock = accept();
-            _client = sock;
-            _in  = sock. getInputStream();
-            _out = sock.getOutputStream();
-
-
-            // Establish web socket with handshake; easier with a buffered reader
-            BufferedReader br = new BufferedReader(new InputStreamReader(_in, StandardCharsets.US_ASCII));
-            String key = null;
-            // TCP can deliver the request in several chunks. ready() is not an
-            // end-of-headers test; wait for the terminating empty line.
-            String line;
-            while( (line = br.readLine()) != null && !line.isEmpty() ) {
-                if( line.startsWith("Sec-WebSocket-Key: ") )
-                    key = line.substring(19);
-            }
-            if( key==null || line==null ) {
-                sock.close();
-                super.close();
-                throw new IOException("Incomplete WebSocket upgrade request");
-            }
-            // Magic handshake
-            byte[] response = ("HTTP/1.1 101 Switching Protocols\r\n"
-                               + "Connection: Upgrade\r\n"
-                               + "Upgrade: websocket\r\n"
-                               + "Sec-WebSocket-Accept: "
-                               + Base64.getEncoder().encodeToString(MessageDigest.getInstance("SHA-1").digest((key + "258EAFA5-E914-47DA-95CA-C5AB0DC85B11").getBytes( StandardCharsets.UTF_8 )))
-                               + "\r\n\r\n").getBytes( StandardCharsets.UTF_8 );
-            _out.write(response,0,response.length);
-            _out.flush();
-        } catch( IOException | NoSuchAlgorithmException | RuntimeException | Error failure ) {
-            if( _http != null ) _http.stop(0);
-            if( _client != null ) {
-                try { _client.close(); } catch( IOException ignored ) {}
-            }
-            try { super.close(); } catch( IOException ignored ) {}
-            throw failure;
-        }
-    }
-
-    final byte[] _ins = new byte[1024];
-    final byte[] _str = new byte[1024];
-    final byte[] _key = new byte[4];
-    int _x, _len;
-    private int rawget() { assert _x<_len; return _ins[_x++]&0xFF; }
-
-    // TODO: Flip to Direct Byte Buffer, this is just a poor-mans version
-    private void flipRead() throws IOException {
-        // Move _x to _len to offset 0
-        System.arraycopy(_ins,_x,_ins,0,(_len-_x));
-        _len = _len-_x;
-        _x=0;
-        // Read more
-        int len = _in.read(_ins,_len,_ins.length-_len);
-        if( len == -1 )
-            throw Utils.TODO(); // EOF
-        _len += len;
-    }
-    // Block until you read at least len
-    private void atLeast(int len) throws IOException {
-        if( _x+len <= _len ) return;
-        flipRead();
-    }
-
-
-    // Classic read from browser client.  Encoded, so decoded here
-    public String get() throws IOException {
-        atLeast(1);             // Need 1 byte for opcode
-        int op = rawget();
-        if( (op&0x80)!=0x80 )   // FIN bit not set?
-            throw Utils.TODO( "Multi-part from client: " + op ); // Multipart message
-        op &= 0x7F;             // Strip FIN bit
-        switch( op&15) {
-        case 1: {
-            atLeast(5);         // Min message length
-            // Message length
-            int len = rawget()-128;
-            if( len > 125 ) {
-                if( len > 126 )
-                    throw Utils.TODO(); // Multi-byte length
-                len = (rawget()<<8) | rawget();
-            }
-            atLeast(len+4);     // Rest of message
-            // Encoding key
-            _key[0] = (byte)rawget();
-            _key[1] = (byte)rawget();
-            _key[2] = (byte)rawget();
-            _key[3] = (byte)rawget();
-
-            // Decode bytes
-            for( int i=0; i<len; i++ )
-                _str[i] = (byte)(rawget() ^ _key[i & 3]);
-
-            return new String(_str,0,len);
-        }
-            // Client closes
-        case 8: return null;
-            // Ping
-        case 9:
-            // Send a PONG back.  TODO: echo PING data in the PONG
-            _out.write(0x8A); // FIN + PONG
-            _out.write(0x00); // LENGTH==0
-            return get();
-            // Not (yet) implemented: continuation frames, ping/pong
-        default:
-            throw Utils.TODO("Unexpected op from client: "+op); // Multi-part message
-        }
-    }
-
-    // Classic put to browser client.  No encoding.
-    public void put(String msg) throws IOException {
-        int len = msg.length();
-        if( len <= 125 ) {
-            _out.write(129); // FIN, opcode 1 - whole text message
-            _out.write(len);
-            for( int i=0; i<msg.length(); i++ )
-                _out.write(msg.charAt(i));
-            return;
-        }
-        if( len > 65535 )
-            throw Utils.TODO("MOAR LENGTH");
-        _out.write(129);        // FIN, opcode 1 - whole text message
-        _out.write(126);        // Length is 16b
-        _out.write(len>>>8);
-        _out.write(len&255);
-        for( int i=0; i<msg.length(); i++ )
-            _out.write(msg.charAt(i));
-    }
-
-    @Override public void close() throws IOException {
-        try {
-            if( _out != null ) {
-                _out.write(new byte[]{(byte)0x88, 0}); // Complete, empty close frame
-                _out.flush();
-            }
-        } finally {
-            if( _http != null ) _http.stop(0);
-            try {
-                if( _client != null ) _client.close();
-            } finally {
-                super.close();
-            }
-        }
-    }
-}