Add shared graph viewer to all chapters

19 files changed, 141 insertions, 340 deletions

diff --git a/chapter11/src/main/java/com/seaofnodes/simple/GraphVisualizer.java b/chapter11/src/main/java/com/seaofnodes/simple/GraphVisualizer.java
deleted file mode 100644
index 604770a4..00000000
--- a/chapter11/src/main/java/com/seaofnodes/simple/GraphVisualizer.java
+++ /dev/null
@@ -1,280 +0,0 @@
-package com.seaofnodes.simple;
-
-import com.seaofnodes.simple.Parser;
-import com.seaofnodes.simple.node.*;
-
-import java.util.*;
-
-/**
- * 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.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(stop, scope);
-        StringBuilder sb = new StringBuilder();
-        sb.append("digraph chapter11 {\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 ScopeNode || n==Parser.XCTRL)
-                continue; // Do not emit, rolled into MultiNode or Scope cluster already
-            if (_separateControlCluster && doCtrl && !n.isCFG()) continue;
-            if (_separateControlCluster && !doCtrl && n.isCFG()) 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;
-                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.isCFG()) 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).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 level=1;
-        for( int idx = scope._scopes.size()-1; idx>=0; idx-- ) {
-            var syms = scope._scopes.get(idx);
-            String scopeName = makeScopeName(scope, level);
-            sb.append("\tsubgraph cluster_").append(scopeName).append(" {\n"); // Magic "cluster_" in the subgraph name
-            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
-            int scopeLevel = scope._scopes.size()-level;
-            sb.append("\t\t\t<TR><TD BGCOLOR=\"cyan\">").append(scopeLevel).append("</TD>");
-            for(String name: syms.keySet())
-                sb.append("<TD PORT=\"").append(makePortName(scopeName, name)).append("\">").append(name).append("</TD>");
-            sb.append("</TR>\n");
-            sb.append("\t\t\t</TABLE>>];\n");
-            level++;
-        }
-        // 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( level-1 ) ); // 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.isCFG() )
-                        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=1;
-        for( int i = scope._scopes.size()-1; i>=0; i-- ) {
-            var syms = scope._scopes.get(i);
-            String scopeName = makeScopeName(scope, level);
-            for( String name : syms.keySet() ) {
-                int idx = syms.get(name);
-                Node def = scope.in(idx);
-                while( def instanceof ScopeNode lazy )
-                    def = lazy.in(idx);
-                if( def==null ) continue;
-                sb.append("\t")
-                  .append(scopeName).append(":")
-                  .append('"').append(makePortName(scopeName, name)).append('"') // wrap port name with quotes because $ctrl is not valid unquoted
-                  .append(" -> ");
-                if( def instanceof CProjNode proj ) {
-                    String mname = proj.ctrl().uniqueName();
-                    sb.append(mname).append(":p").append(proj._idx);
-                } else sb.append(def.uniqueName());
-                sb.append(";\n");
-            }
-            level++;
-        }
-    }
-
-    /**
-     * Finds all nodes in the graph.
-     */
-    private Collection<Node> findAll(Node stop, Node scope) {
-        final HashMap<Integer, Node> all = new HashMap<>();
-        for( Node n : stop._inputs )
-            walk(all, n);
-        if( scope != null )
-            for( Node n : scope._inputs )
-                walk(all, n);
-        return all.values();
-    }
-
-    /**
-     * Walk a subgraph and populate distinct nodes in the all list.
-     */
-    private 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/chapter11/src/main/java/com/seaofnodes/simple/IterPeeps.java b/chapter11/src/main/java/com/seaofnodes/simple/IterPeeps.java
index b2b76777..9d2b913f 100644
--- a/chapter11/src/main/java/com/seaofnodes/simple/IterPeeps.java
+++ b/chapter11/src/main/java/com/seaofnodes/simple/IterPeeps.java
@@ -57,7 +57,7 @@ public abstract class IterPeeps {
     /**
      * Iterate peepholes to a fixed point
      */
-    public static StopNode iterate(StopNode stop, boolean show) {
+    public static StopNode iterate(StopNode stop) {
         assert progressOnList(stop);
         int cnt=0;
 
@@ -65,9 +65,14 @@ public abstract class IterPeeps {
         while( (n=WORK.pop()) != null ) {
             if( n.isDead() )  continue;
             cnt++;              // Useful for debugging, searching which peephole broke things
+            var obs = Parser.PARSER == null ? null : Parser.PARSER._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
@@ -90,10 +95,9 @@ public abstract class IterPeeps {
             }
             if( n.isUnused() && !(n instanceof StopNode) )
                 n.kill();       // Just plain dead
+            if( obs != null ) obs.after(n, x, true);
         }
 
-        if( show )
-            System.out.println(new GraphVisualizer().generateDotOutput(stop,null,null));
         GlobalCodeMotion.buildCFG(stop);
         return stop;
     }
diff --git a/chapter11/src/main/java/com/seaofnodes/simple/Parser.java b/chapter11/src/main/java/com/seaofnodes/simple/Parser.java
index e367f499..7008512f 100644
--- a/chapter11/src/main/java/com/seaofnodes/simple/Parser.java
+++ b/chapter11/src/main/java/com/seaofnodes/simple/Parser.java
@@ -1,5 +1,7 @@
 package com.seaofnodes.simple;
 
+import com.seaofnodes.graph.GraphObserver;
+
 import com.seaofnodes.simple.node.*;
 import com.seaofnodes.simple.type.*;
 
@@ -14,6 +16,12 @@ import java.util.*;
  */
 public class Parser {
 
+    // Current compilation context; the observer belongs to the parser.
+    public static Parser PARSER;
+    public GraphObserver<Node> _obs;
+    public int pos() { return _lexer._position; }
+
+
     /**
      * A Global Static, unique to each compilation.  This is a public, so we
      * can make constants everywhere without having to thread the StartNode
@@ -80,6 +88,7 @@ public class Parser {
     public static Map<String, TypeStruct> OBJS = new HashMap<>();
 
     public Parser(String source, TypeInteger arg) {
+        PARSER = this;
         Node.reset();
         IterPeeps.reset();
         OBJS.clear();
@@ -109,8 +118,7 @@ public class Parser {
 
     private Node ctrl(Node n) { return _scope.ctrl(n); }
 
-    public StopNode parse() { return parse(false); }
-    public StopNode parse(boolean show) {
+    public StopNode parse() {
         _xScopes.push(_scope);
         // Enter a new scope for the initial control and arguments
         _scope.push();
@@ -123,7 +131,6 @@ public class Parser {
         _xScopes.pop();
         if (!_lexer.isEOF()) throw error("Syntax error, unexpected " + _lexer.getAnyNextToken());
         STOP.peephole();
-        if( show ) showGraph();
         return STOP;
     }
 
@@ -164,7 +171,6 @@ 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
         // declarations of vars with struct type are handled in parseExpressionStatement due
         // to ambiguity
@@ -381,14 +387,7 @@ public class Parser {
         return ret;
     }
 
-    /**
-     * Dumps out the node graph
-     * @return {@code null}
-     */
-    Node showGraph() {
-        System.out.println(new GraphVisualizer().generateDotOutput(STOP,_scope,_xScopes));
-        return null;
-    }
+
 
     /**
      * Parses an expression statement or a declaration statement where type is a struct
diff --git a/chapter11/src/main/java/com/seaofnodes/simple/node/AddNode.java b/chapter11/src/main/java/com/seaofnodes/simple/node/AddNode.java
index 2cc0b465..b88e13b5 100644
--- a/chapter11/src/main/java/com/seaofnodes/simple/node/AddNode.java
+++ b/chapter11/src/main/java/com/seaofnodes/simple/node/AddNode.java
@@ -9,8 +9,6 @@ public class AddNode extends Node {
 
     @Override public String label() { return "Add"; }
 
-    @Override public String glabel() { return "+"; }
-
     @Override
     StringBuilder _print1(StringBuilder sb, BitSet visited) {
         in(1)._print0(sb.append("("), visited);
diff --git a/chapter11/src/main/java/com/seaofnodes/simple/node/BoolNode.java b/chapter11/src/main/java/com/seaofnodes/simple/node/BoolNode.java
index 8719e4d5..ab577aa6 100644
--- a/chapter11/src/main/java/com/seaofnodes/simple/node/BoolNode.java
+++ b/chapter11/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
     StringBuilder _print1(StringBuilder sb, BitSet visited) {
         in(1)._print0(sb.append("("), visited);
         in(2)._print0(sb.append(op()), visited);
diff --git a/chapter11/src/main/java/com/seaofnodes/simple/node/DivNode.java b/chapter11/src/main/java/com/seaofnodes/simple/node/DivNode.java
index 08ce70b8..d6ecfb69 100644
--- a/chapter11/src/main/java/com/seaofnodes/simple/node/DivNode.java
+++ b/chapter11/src/main/java/com/seaofnodes/simple/node/DivNode.java
@@ -10,8 +10,6 @@ public class DivNode extends Node {
 
     @Override public String label() { return "Div"; }
 
-    @Override public String glabel() { return "//"; }
-
     @Override
     StringBuilder _print1(StringBuilder sb, BitSet visited) {
         in(1)._print0(sb.append("("), visited);
diff --git a/chapter11/src/main/java/com/seaofnodes/simple/node/LoadNode.java b/chapter11/src/main/java/com/seaofnodes/simple/node/LoadNode.java
index 296237f4..39bbaff1 100644
--- a/chapter11/src/main/java/com/seaofnodes/simple/node/LoadNode.java
+++ b/chapter11/src/main/java/com/seaofnodes/simple/node/LoadNode.java
@@ -29,9 +29,6 @@ public class LoadNode extends MemOpNode {
     public String label() { return "Load"; }
 
     @Override
-    public String glabel() { return "."+_name; }
-
-    @Override
     StringBuilder _print1(StringBuilder sb, BitSet visited) { return sb.append(".").append(_name); }
 
     @Override
diff --git a/chapter11/src/main/java/com/seaofnodes/simple/node/MinusNode.java b/chapter11/src/main/java/com/seaofnodes/simple/node/MinusNode.java
index 9b687613..fa252903 100644
--- a/chapter11/src/main/java/com/seaofnodes/simple/node/MinusNode.java
+++ b/chapter11/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
     StringBuilder _print1(StringBuilder sb, BitSet visited) {
         in(1)._print0(sb.append("(-"), visited);
diff --git a/chapter11/src/main/java/com/seaofnodes/simple/node/MulNode.java b/chapter11/src/main/java/com/seaofnodes/simple/node/MulNode.java
index 7e9f88a2..6a6c82f9 100644
--- a/chapter11/src/main/java/com/seaofnodes/simple/node/MulNode.java
+++ b/chapter11/src/main/java/com/seaofnodes/simple/node/MulNode.java
@@ -10,8 +10,6 @@ public class MulNode extends Node {
 
     @Override public String label() { return "Mul"; }
 
-    @Override public String glabel() { return "*"; }
-
     @Override
     StringBuilder _print1(StringBuilder sb, BitSet visited) {
         in(1)._print0(sb.append("("), visited);
diff --git a/chapter11/src/main/java/com/seaofnodes/simple/node/NewNode.java b/chapter11/src/main/java/com/seaofnodes/simple/node/NewNode.java
index c00fee62..1c82d5f5 100644
--- a/chapter11/src/main/java/com/seaofnodes/simple/node/NewNode.java
+++ b/chapter11/src/main/java/com/seaofnodes/simple/node/NewNode.java
@@ -18,9 +18,6 @@ public class NewNode extends Node {
     public String label() { return "new"; }
 
     @Override
-    public String glabel() { return "new " + _ptr._obj._name; }
-
-    @Override
     StringBuilder _print1(StringBuilder sb, BitSet visited) {
         sb.append("new ");
         return sb.append(_ptr._obj.str());
diff --git a/chapter11/src/main/java/com/seaofnodes/simple/node/Node.java b/chapter11/src/main/java/com/seaofnodes/simple/node/Node.java
index e5bad801..5ebcf843 100644
--- a/chapter11/src/main/java/com/seaofnodes/simple/node/Node.java
+++ b/chapter11/src/main/java/com/seaofnodes/simple/node/Node.java
@@ -72,17 +72,11 @@ public abstract class Node implements OutNode {
     // 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 "=="
-    public String glabel() { return label(); }
-
-
     // ------------------------------------------------------------------------
 
     // Debugger Printing.
@@ -287,13 +281,14 @@ public abstract class Node implements OutNode {
      * 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 (_disablePeephole) {
-            _type = compute();
-            return this;        // Peephole optimizations turned off
-        }
+    public final Node peephole() {
+        if( _disablePeephole ) { _type = compute(); return this; }
+        var obs = IterPeeps.midAssert() ? null : Parser.PARSER == null ? null : Parser.PARSER._obs;
+        if( obs != null ) obs.before(this);
         Node n = peepholeOpt();
-        return n==null ? this : deadCodeElim(n.peephole()); // Cannot return null for no-progress
+        Node rez = n == null ? this : deadCodeElim(n.peephole());
+        if( obs != null ) obs.after(this, n == null ? null : rez, false);
+        return rez;
     }
 
     /**
@@ -451,6 +446,8 @@ public abstract class Node implements OutNode {
     // retry the peephole.  Track a set of Nodes dependent on `this`, and
     // revisit them if `this` changes.
     ArrayList<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 its not an input
@@ -461,6 +458,8 @@ public abstract class Node implements OutNode {
         // Running peepholes during the big assert cannot have side effects
         // like adding dependencies.
         if( IterPeeps.midAssert() ) return this;
+        var obs = IterPeeps.midAssert() ? null : Parser.PARSER == null ? null : Parser.PARSER._obs;
+        if( obs != null ) obs.dep(this, dep);
         if( _deps==null ) _deps = new ArrayList<>();
         if( Utils.find(_deps  ,dep) != -1 ) return this; // Already on list
         if( Utils.find(_inputs,dep) != -1 ) return this; // No need for deps on immediate neighbors
diff --git a/chapter11/src/main/java/com/seaofnodes/simple/node/NotNode.java b/chapter11/src/main/java/com/seaofnodes/simple/node/NotNode.java
index 05e44eb0..3d85b220 100644
--- a/chapter11/src/main/java/com/seaofnodes/simple/node/NotNode.java
+++ b/chapter11/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
     StringBuilder _print1(StringBuilder sb, BitSet visited) {
         in(1)._print0(sb.append("(!"), visited);
diff --git a/chapter11/src/main/java/com/seaofnodes/simple/node/PhiNode.java b/chapter11/src/main/java/com/seaofnodes/simple/node/PhiNode.java
index ddd0ca72..52f098fa 100644
--- a/chapter11/src/main/java/com/seaofnodes/simple/node/PhiNode.java
+++ b/chapter11/src/main/java/com/seaofnodes/simple/node/PhiNode.java
@@ -18,8 +18,6 @@ public class PhiNode extends Node {
 
     @Override public String label() { return "Phi_"+_label; }
 
-    @Override public String glabel() { return "&phi;_"+_label; }
-
     @Override
     StringBuilder _print1(StringBuilder sb, BitSet visited) {
         if( !(region() instanceof RegionNode r) || r.inProgress() )
diff --git a/chapter11/src/main/java/com/seaofnodes/simple/node/StopNode.java b/chapter11/src/main/java/com/seaofnodes/simple/node/StopNode.java
index 2bef4f50..da32651a 100644
--- a/chapter11/src/main/java/com/seaofnodes/simple/node/StopNode.java
+++ b/chapter11/src/main/java/com/seaofnodes/simple/node/StopNode.java
@@ -67,8 +67,7 @@ public class StopNode extends CFGNode {
         return addDef(node);
     }
 
-    public StopNode iterate(            ) { return IterPeeps.iterate(this,false).typeCheck(); }
-    public StopNode iterate(boolean show) { return IterPeeps.iterate(this,show ).typeCheck(); }
+    public StopNode iterate() { return IterPeeps.iterate(this).typeCheck(); }
     StopNode typeCheck() {
         String err = walk( Node::err );
         if( err != null ) throw new RuntimeException(err);
diff --git a/chapter11/src/main/java/com/seaofnodes/simple/node/StoreNode.java b/chapter11/src/main/java/com/seaofnodes/simple/node/StoreNode.java
index db8e2ce6..5b30b3ec 100644
--- a/chapter11/src/main/java/com/seaofnodes/simple/node/StoreNode.java
+++ b/chapter11/src/main/java/com/seaofnodes/simple/node/StoreNode.java
@@ -24,8 +24,6 @@ public class StoreNode extends MemOpNode {
     @Override
     public String label() { return "Store"; }
     @Override
-    public String glabel() { return "."+_name+" ="; }
-    @Override
     public boolean isMem() { return true; }
     public Node val() { return in(3); }
 
diff --git a/chapter11/src/main/java/com/seaofnodes/simple/node/SubNode.java b/chapter11/src/main/java/com/seaofnodes/simple/node/SubNode.java
index 5ddcdb68..515b21e8 100644
--- a/chapter11/src/main/java/com/seaofnodes/simple/node/SubNode.java
+++ b/chapter11/src/main/java/com/seaofnodes/simple/node/SubNode.java
@@ -11,8 +11,6 @@ public class SubNode extends Node {
 
     @Override public String label() { return "Sub"; }
 
-    @Override public String glabel() { return "-"; }
-
     @Override
     StringBuilder _print1(StringBuilder sb, BitSet visited) {
         in(1)._print0(sb.append("("), visited);
diff --git a/chapter11/src/main/java/com/seaofnodes/simple/print/SimpleGraphAdapter.java b/chapter11/src/main/java/com/seaofnodes/simple/print/SimpleGraphAdapter.java
new file mode 100644
index 00000000..38acb8cd
--- /dev/null
+++ b/chapter11/src/main/java/com/seaofnodes/simple/print/SimpleGraphAdapter.java
@@ -0,0 +1,62 @@
+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 11'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>();
+        String[] names = n instanceof ScopeNode scope && n.nIns() != 0 ? scope.reverseNames() : null;
+        for( int i = 0; i < n.nIns(); i++ ) {
+            String name = names == null || i >= names.length ? null : names[i];
+            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 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.isCFG() ? Kind.CTRL : isMem(n) ? Kind.MEM : Kind.DATA;
+    }
+
+    private Role role(Node n, int i) {
+        if( n instanceof ScopeNode || n instanceof ConstantNode || 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.isCFG() ? 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( i == 1 && (n instanceof MemOpNode || n instanceof ReturnNode) ) 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/chapter11/src/main/java/com/seaofnodes/simple/print/SimpleGraphObserver.java b/chapter11/src/main/java/com/seaofnodes/simple/print/SimpleGraphObserver.java
new file mode 100644
index 00000000..af20e147
--- /dev/null
+++ b/chapter11/src/main/java/com/seaofnodes/simple/print/SimpleGraphObserver.java
@@ -0,0 +1,43 @@
+package com.seaofnodes.simple.print;
+
+import com.seaofnodes.graph.GraphCapture;
+import com.seaofnodes.graph.GraphViewer;
+import com.seaofnodes.simple.Parser;
+import com.seaofnodes.simple.node.Node;
+import java.util.ArrayList;
+import java.io.IOException;
+
+/** Chapter 11's compilation context; capture and event bookkeeping are shared. */
+public class SimpleGraphObserver extends GraphCapture<Node> {
+    private Parser _parser;
+    private Node _ret;
+    private String _phase;
+    public SimpleGraphObserver() { super(new SimpleGraphAdapter()); }
+    public static void main(String[] args) throws IOException {
+        GraphViewer.run(new SimpleGraphObserver());
+    }
+    @Override protected void compile(String src) {
+        _parser = new Parser(src);
+        _parser._obs = this;
+        _phase = "Parse";
+        _ret = _parser.parse();
+        phase(_phase);
+        _phase = "Iter";
+        com.seaofnodes.simple.IterPeeps.iterate(_parser.STOP);
+        phase(_phase);
+    }
+    @Override protected String phase() { return _phase; }
+    @Override protected int pos() { return "Parse".equals(_phase) ? _parser.pos() : -1; }
+    @Override protected void detach() {
+        if( _parser != null ) _parser._obs = null;
+        _parser = null;
+        _ret = null;
+    }
+    @Override protected void roots(ArrayList<Node> roots) {
+        roots.add(Parser.START);
+        roots.add(_parser.STOP);
+        roots.add(_parser._scope);
+        roots.addAll(_parser._xScopes);
+        roots.add(_ret);
+    }
+}
diff --git a/chapter11/src/test/java/com/seaofnodes/simple/SchedulerTest.java b/chapter11/src/test/java/com/seaofnodes/simple/SchedulerTest.java
index 32c9c0c5..853999b1 100644
--- a/chapter11/src/test/java/com/seaofnodes/simple/SchedulerTest.java
+++ b/chapter11/src/test/java/com/seaofnodes/simple/SchedulerTest.java
@@ -31,7 +31,7 @@ if (arg) v.f=1;
 return i;
 """);
         StopNode._disablePeephole = true;
-        StopNode stop = parser.parse(true);//.iterate();
+        StopNode stop = parser.parse();//.iterate();
         var eval = new Evaluator(stop);
         assertEquals(2L, eval.evaluate(1, 10));
     }
@@ -46,7 +46,7 @@ S v0=new S;
 if(arg) v0.f=1;
 return v0;
 """);
-        StopNode stop = parser.parse(false).iterate();
+        StopNode stop = parser.parse().iterate();
         var eval = new Evaluator(stop);
         assertObj(eval.evaluate(0, 10), "S", 0L);
         assertObj(eval.evaluate(1, 10), "S", 1L);
@@ -65,7 +65,7 @@ i=v.f;
 if (arg) v.f=1;
 return i;
 """);
-        StopNode stop = parser.parse(false).iterate();
+        StopNode stop = parser.parse().iterate();
         var eval = new Evaluator(stop);
         assertEquals(2L, eval.evaluate(0, 10));
         assertEquals(2L, eval.evaluate(1, 10));