Allow post ++, --

Fix eval auto-string result.  Fix tests hacked because of this.
Turn on BrainFuck in ch15,16,17, also disabled because of this.  Use new features in BrainFuck.
Fix bug not lifting forward refs; add a toString to Vars.
Fix some missing addDeps.
Remove large complex not-productive peep.
Upcast after "while" tests.  Improves a bunch of tests.
Remove dead getBlockStart.

29 files changed, 174 insertions, 153 deletions

diff --git a/chapter17/src/main/java/com/seaofnodes/simple/Parser.java b/chapter17/src/main/java/com/seaofnodes/simple/Parser.java
index d2a1a9ae..9710be30 100644
--- a/chapter17/src/main/java/com/seaofnodes/simple/Parser.java
+++ b/chapter17/src/main/java/com/seaofnodes/simple/Parser.java
@@ -96,7 +96,7 @@ public class Parser {
     // Mapping from a type name to a Type.  The string name matches
     // `type.str()` call.  No TypeMemPtrs are in here, because Simple does not
     // have C-style '*ptr' references.
-    public final HashMap<String, Type> TYPES;
+    public static HashMap<String, Type> TYPES;
 
     // Mapping from a type name to the constructor for a Type.
     public final HashMap<String, StructNode> INITS;
@@ -267,6 +267,7 @@ public class Parser {
         // the loop predicate.  Note that body Scope is still our current scope.
         ctrl(ifF);
         _xScopes.push(_breakScope = _scope.dup());
+        _breakScope.upcast(ifF,pred,true); // Up-cast predicate
 
         // No continues yet
         _continueScope = null;
@@ -274,6 +275,7 @@ public class Parser {
         // Parse the true side, which corresponds to loop body
         // Our current scope is the body Scope
         ctrl(ifT.unkeep());     // set ctrl token to ifTrue projection
+        _scope.upcast(ifT,pred,false); // Up-cast predicate
         parseStatement();       // Parse loop body
 
         // Merge the loop bottom into other continue statements
@@ -302,7 +304,8 @@ public class Parser {
         // the scope is the exit scope after the exit test.
         _xScopes.pop();
         _xScopes.push(exit);
-        return _scope = exit;
+        _scope = exit;
+        return _scope;
     }
 
     private ScopeNode jumpTo(ScopeNode toScope) {
@@ -438,7 +441,7 @@ public class Parser {
             // need to check the final bit.
             if( _scope.in(def._idx)._type!=Type.TOP && def._final )
                 throw error("Cannot reassign final '"+name+"'");
-            t = def._type; // Declared field type
+            t = def.type(); // Declared field type
         }
 
         // Auto-widen int to float
@@ -527,7 +530,7 @@ public class Parser {
         for( int i=lexlen; i<varlen; i++ ) {
             s.addDef(_scope.in(i));
             ScopeMinNode.Var v = _scope._vars.at(i);
-            fs[i-lexlen] = Field.make(v._name,v._type,ALIAS++,v._final);
+            fs[i-lexlen] = Field.make(v._name,v.type(),ALIAS++,v._final);
         }
         TypeStruct ts = s._ts = TypeStruct.make(typeName, fs);
         TYPES.put(typeName, TypeMemPtr.make(ts));
@@ -550,7 +553,7 @@ public class Parser {
         if( tname==null ) return null;
         // Convert the type name to a type.
         Type t0 = TYPES.get(tname);
-        Type t1 = t0 == null ? TypeMemPtr.make(TypeStruct.make(tname)) : t0; // Null: assume a forward ref type
+        Type t1 = t0 == null ? TypeMemPtr.make(TypeStruct.makeFRef(tname)) : t0; // Null: assume a forward ref type
         // Nest arrays and '?' as needed
         while( true ) {
             assert !(t1 instanceof TypeStruct);
@@ -744,23 +747,33 @@ public class Parser {
      * Parse a primary expression:
      *
      * <pre>
-     *     primaryExpr : integerLiteral | Identifier | true | false | null | new Type | '(' expression ')'
+     *     primaryExpr : integerLiteral | true | false | null | new Type | '(' expression ')' | Id['++','--']
      * </pre>
      * @return a primary {@link Node}, never {@code null}
      */
     private Node parsePrimary() {
         if( _lexer.isNumber(_lexer.peek()) ) return parseLiteral();
-        if( match("(") ) return require(parseExpression(), ")");
         if( matchx("true" ) ) return con(1);
         if( matchx("false") ) return ZERO;
         if( matchx("null" ) ) return con(TypeMemPtr.NULLPTR);
+        if( match("(") ) return require(parseExpression(), ")");
         if( matchx("new"  ) ) return alloc();
         // Expect an identifier now
-        String name = _lexer.matchId();
-        if( name == null) throw errorSyntax("an identifier or expression");
-        ScopeMinNode.Var n = _scope.lookup(name);
-        if( n!=null ) return _scope.in(n);
-        throw error("Undefined name '" + name + "'");
+        ScopeMinNode.Var n = requireLookupId("an identifier or expression");
+        Node rvalue = _scope.in(n).keep();
+        if( matchx("++") ) _scope.update(n,new AddNode(rvalue,con( 1)).peephole());
+        if( matchx("--") ) _scope.update(n,new AddNode(rvalue,con(-1)).peephole());
+        return rvalue.unkeep();
+    }
+
+    ScopeMinNode.Var requireLookupId(String msg) {
+        String id = _lexer.matchId();
+        if( id == null || KEYWORDS.contains(id) )
+            throw errorSyntax(msg);
+        ScopeMinNode.Var n = _scope.lookup(id);
+        if( n==null )
+            throw error("Undefined name '" + id + "'");
+        return n;
     }
 
     /**
diff --git a/chapter17/src/main/java/com/seaofnodes/simple/node/CProjNode.java b/chapter17/src/main/java/com/seaofnodes/simple/node/CProjNode.java
index 3d6fd1fa..d2f1bbe1 100644
--- a/chapter17/src/main/java/com/seaofnodes/simple/node/CProjNode.java
+++ b/chapter17/src/main/java/com/seaofnodes/simple/node/CProjNode.java
@@ -52,10 +52,6 @@ public class CProjNode extends CFGNode {
     }
 
     @Override
-    public Node getBlockStart() {
-        return ctrl() instanceof IfNode ? this : ctrl().getBlockStart();
-    }
-    @Override
     boolean eq( Node n ) { return _idx == ((CProjNode)n)._idx; }
 
     @Override
diff --git a/chapter17/src/main/java/com/seaofnodes/simple/node/IfNode.java b/chapter17/src/main/java/com/seaofnodes/simple/node/IfNode.java
index 3cce89ab..41de4c82 100644
--- a/chapter17/src/main/java/com/seaofnodes/simple/node/IfNode.java
+++ b/chapter17/src/main/java/com/seaofnodes/simple/node/IfNode.java
@@ -66,6 +66,4 @@ public class IfNode extends CFGNode implements MultiNode {
                 unreach.add((CProjNode)proj);
         super._walkUnreach(visit,unreach);
     }
-
-    @Override public Node getBlockStart() { return ctrl().getBlockStart(); }
 }
diff --git a/chapter17/src/main/java/com/seaofnodes/simple/node/LoadNode.java b/chapter17/src/main/java/com/seaofnodes/simple/node/LoadNode.java
index d15d4f83..2c0afda2 100644
--- a/chapter17/src/main/java/com/seaofnodes/simple/node/LoadNode.java
+++ b/chapter17/src/main/java/com/seaofnodes/simple/node/LoadNode.java
@@ -33,10 +33,13 @@ public class LoadNode extends MemOpNode {
 
     @Override
     public Type compute() {
-        if( mem()._type instanceof TypeMem mem &&
-            // No constant folding if ptr might null-check
-            _declaredType != mem._t && err()==null ) {
-            return  _declaredType.join(mem._t);
+        if( mem()._type instanceof TypeMem mem ) {
+            // Update declared forward ref to the actual
+            if( _declaredType.isFRef() && mem._t instanceof TypeMemPtr tmp && !tmp.isFRef() )
+                _declaredType = tmp;
+            // No lifting if ptr might null-check
+            if( err()==null )
+                return _declaredType.join(mem._t);
         }
         return _declaredType;
     }
diff --git a/chapter17/src/main/java/com/seaofnodes/simple/node/MemOpNode.java b/chapter17/src/main/java/com/seaofnodes/simple/node/MemOpNode.java
index c7a1efec..82aab8ac 100644
--- a/chapter17/src/main/java/com/seaofnodes/simple/node/MemOpNode.java
+++ b/chapter17/src/main/java/com/seaofnodes/simple/node/MemOpNode.java
@@ -1,6 +1,5 @@
 package com.seaofnodes.simple.node;
 
-import com.seaofnodes.simple.type.Field;
 import com.seaofnodes.simple.type.Type;
 import com.seaofnodes.simple.type.TypeMemPtr;
 
@@ -11,7 +10,9 @@ public abstract class MemOpNode extends Node {
 
     public final String _name;
     public final int _alias;
-    public final Type _declaredType;
+    // Declared type; not final because it might be a forward-reference
+    // which will be lazily improved when the reference is declared.
+    public Type _declaredType;
 
     public MemOpNode(String name, int alias, Type glb, Node mem, Node ptr, Node off) {
         super(null, mem, ptr, off);
diff --git a/chapter17/src/main/java/com/seaofnodes/simple/node/Node.java b/chapter17/src/main/java/com/seaofnodes/simple/node/Node.java
index 462a403c..c67fb910 100644
--- a/chapter17/src/main/java/com/seaofnodes/simple/node/Node.java
+++ b/chapter17/src/main/java/com/seaofnodes/simple/node/Node.java
@@ -278,6 +278,7 @@ public abstract class Node implements OutNode {
             int idx = n._inputs.find(this);
             n._inputs.set(idx,nnn);
             nnn.addUse(n);
+            IterPeeps.addAll(n._outputs);
         }
         kill();
     }
@@ -419,7 +420,7 @@ public abstract class Node implements OutNode {
      * And more folding:
      * <pre>   ary + ((idx<<2) + 16)</pre>
      * And during code-gen:
-     * <pre>   MOV4 Rary,Ridx,16 // or some such hardware-specific notation </pre>
+     * <pre>   MOV4 Rary,[Ridx<<2 +16] // or some such hardware-specific notation </pre>
      * <p>
      * {@link #idealize} has a very specific calling convention:
      * <ul>
@@ -542,9 +543,6 @@ public abstract class Node implements OutNode {
     /** Is this Node Memory related */
     public boolean isMem() { return false; }
 
-    /** Return block start from a isCFG() */
-    public Node getBlockStart() { return null; }
-
     /** Pinned in the schedule; these are data nodes whose input#0 is not allowed to change */
     public boolean isPinned() { return false; }
 
diff --git a/chapter17/src/main/java/com/seaofnodes/simple/node/RegionNode.java b/chapter17/src/main/java/com/seaofnodes/simple/node/RegionNode.java
index 941de76b..a55bb479 100644
--- a/chapter17/src/main/java/com/seaofnodes/simple/node/RegionNode.java
+++ b/chapter17/src/main/java/com/seaofnodes/simple/node/RegionNode.java
@@ -72,65 +72,9 @@ public class RegionNode extends CFGNode {
             p1.in(0) instanceof IfNode iff )
             return iff.ctrl();
 
-
-        // Look for direct uses of a guarded expression, and replace with the guard result.
-        if( !(idom() instanceof StartNode) && // Dead or dying
-            !(this instanceof LoopNode) ) {
-            VISIT.clear();
-            boolean progress = false;
-            outer:
-            for( int i=1; i<nIns(); i++ ) {
-                CFGNode idom = cfg(i);
-                while( !(idom instanceof CProjNode cproj) ) {
-                    idom = idom.idom();
-                    if( idom==null || idom.idepth() < idom().idepth() )
-                        continue outer;
-                }
-                if( cproj.cfg0() instanceof IfNode iff && cproj.compute()==Type.CONTROL ) {
-                    VISIT.set(iff.pred()._nid);
-                    for( Node out : _outputs )
-                        if( out instanceof PhiNode phi )
-                            progress |= walk(iff,cproj,phi.in(i));
-                }
-            }
-            if( progress )
-                return this;
-        }
-
         return null;
     }
 
-    // A walk that can be cutoff early
-    private static final BitSet VISIT = new BitSet();
-    private boolean walk( IfNode iff, CProjNode cproj, Node n ) {
-        if( VISIT.get(n._nid) ) return false;
-        VISIT.set(n._nid);
-        if( n instanceof CFGNode ) return false;
-        if( n.in(0)!=null && n.cfg0().idepth() < iff.idepth() )
-            return false;
-        boolean progress = false;
-        Node pred = iff.pred();
-        if( pred._type.isHighOrConst() ) return false; // This will collapse the IF already
-        for( int i=1; i<n.nIns(); i++ ) {
-            // Using a tested value
-            if( n.in(i) == pred && !(n instanceof CastNode) ) {
-                // Checking pred for T/F
-                Type t = pred._type;
-                Type tcast = cproj._idx==0 ? t.nonZero() : t.makeInit();
-                if( t!=tcast ) { // Progress to cast
-                    Node cast = new CastNode( tcast, cproj, pred ).peephole();
-                    n.setDef( i, cast );
-                    IterPeeps.add(n);
-                    progress = true;
-                } else pred.addDep( this );
-            }
-            if( n.in(i)!=null )
-                progress |= walk(iff,cproj,n.in(i));
-        }
-        return progress;
-    }
-
-
     private int findDeadInput() {
         for( int i=1; i<nIns(); i++ )
             if( in(i)._type==Type.XCONTROL )
@@ -180,6 +124,4 @@ public class RegionNode extends CFGNode {
     @Override boolean eq( Node n ) {
         return !inProgress();
     }
-
-    @Override public Node getBlockStart() { return this; }
 }
diff --git a/chapter17/src/main/java/com/seaofnodes/simple/node/ReturnNode.java b/chapter17/src/main/java/com/seaofnodes/simple/node/ReturnNode.java
index de4eba52..b586a44f 100644
--- a/chapter17/src/main/java/com/seaofnodes/simple/node/ReturnNode.java
+++ b/chapter17/src/main/java/com/seaofnodes/simple/node/ReturnNode.java
@@ -47,6 +47,4 @@ public class ReturnNode extends CFGNode {
             return ctrl();
         return null;
     }
-
-    @Override public Node getBlockStart() { return ctrl().getBlockStart(); }
 }
diff --git a/chapter17/src/main/java/com/seaofnodes/simple/node/ScopeMinNode.java b/chapter17/src/main/java/com/seaofnodes/simple/node/ScopeMinNode.java
index e4874e15..c51349fa 100644
--- a/chapter17/src/main/java/com/seaofnodes/simple/node/ScopeMinNode.java
+++ b/chapter17/src/main/java/com/seaofnodes/simple/node/ScopeMinNode.java
@@ -14,16 +14,28 @@ public class ScopeMinNode extends Node {
     /** The tracked fields are now complex enough to deserve a array-of-structs layout
      */
     public static class Var {
-        public final int _idx;
-        public final String _name;
-        public final Type _type;
-        public final boolean _final;
+        public final int _idx;       // index in containing scope
+        public final String _name;   // Declared name
+        private Type _type;          // Declared type
+        public final boolean _final; // Final field
         public Var(int idx, String name, Type type, boolean xfinal) {
             _idx = idx;
             _name = name;
             _type = type;
             _final = xfinal;
         }
+        public Type type() {
+            if( !_type.isFRef() ) return _type;
+            Type def = Parser.TYPES.get(((TypeMemPtr)_type)._obj._name);
+            return (_type=_type.meet(def));
+        }
+        public Type glb() {
+            Type t = type();
+            return t instanceof TypeMemPtr ? t : t.glb();
+        }
+        @Override public String toString() {
+            return _type.toString()+(_final ? " !": " ")+_name;
+        }
     }
 
     public ScopeMinNode() { _type = TypeMem.BOT; }
diff --git a/chapter17/src/main/java/com/seaofnodes/simple/node/ScopeNode.java b/chapter17/src/main/java/com/seaofnodes/simple/node/ScopeNode.java
index 11e54d82..f7446c51 100644
--- a/chapter17/src/main/java/com/seaofnodes/simple/node/ScopeNode.java
+++ b/chapter17/src/main/java/com/seaofnodes/simple/node/ScopeNode.java
@@ -43,7 +43,7 @@ public class ScopeNode extends ScopeMinNode {
         for( int i=0; i<nIns(); i++ ) {
             if( j < _lexSize._len && i == _lexSize.at(j) ) { sb.append("| "); j++; }
             Var v = _vars.get(i);
-            v._type.print(sb);
+            v.type().print(sb);
             sb.append(" ");
             if( v._final ) sb.append("!");
             sb.append(v._name);
@@ -125,7 +125,7 @@ public class ScopeNode extends ScopeMinNode {
     public Var lookup( String name ) {
         int idx = find(name);
         // -1 is missed in all scopes, not found
-        return idx == -1 ? null : _update(_vars.at(idx),null);
+        return idx == -1 ? null : update(_vars.at(idx),null);
     }
 
     /**
@@ -137,10 +137,10 @@ public class ScopeNode extends ScopeMinNode {
     public void update( String name, Node n ) {
         int idx = find(name);
         assert idx>=0;
-        _update(_vars.at(idx),n);
+        update(_vars.at(idx),n);
     }
 
-    Var _update( ScopeNode.Var v, Node st ) {
+    public Var update( ScopeNode.Var v, Node st ) {
         Node old = in(v._idx);
         if( old instanceof ScopeNode loop ) {
             // Lazy Phi!
@@ -151,7 +151,7 @@ public class ScopeNode extends ScopeMinNode {
                 // Set real Phi in the loop head
                 // The phi takes its one input (no backedge yet) from a recursive
                 // lookup, which might have insert a Phi in every loop nest.
-                : loop.setDef(v._idx,new PhiNode(v._name, v._type instanceof TypeMemPtr ? v._type : v._type.glb(), loop.ctrl(), loop.in(loop._update(v,null)._idx),null).peephole());
+                : loop.setDef(v._idx,new PhiNode(v._name, v.glb(), loop.ctrl(), loop.in(loop.update(v,null)._idx),null).peephole());
             setDef(v._idx,old);
         }
         if( st!=null ) setDef(v._idx,st); // Set new value
@@ -223,9 +223,9 @@ public class ScopeNode extends ScopeMinNode {
                 // If we are in lazy phi mode we need to a lookup
                 // by name as it will trigger a phi creation
                 Var v = _vars.at(i);
-                Node lhs = this.in(this._update(v,null));
-                Node rhs = that.in(that._update(v,null));
-                setDef(i, new PhiNode(v._name, v._type, r, lhs, rhs).peephole());
+                Node lhs = this.in(this.update(v,null));
+                Node rhs = that.in(that.update(v,null));
+                setDef(i, new PhiNode(v._name, v.type(), r, lhs, rhs).peephole());
             }
     }
 
@@ -268,6 +268,8 @@ public class ScopeNode extends ScopeMinNode {
     // This Scope looks for direct variable uses, or certain simple
     // combinations, and replaces the variable with the upcast variant.
     public Node upcast( Node ctrl, Node pred, boolean invert ) {
+        if( ctrl._type == Type.XCONTROL || pred.isDead() )
+            return null; // Dead, do not do anything
         // Invert the If conditional
         if( invert )
             pred = pred instanceof NotNode not ? not.in(1) : IterPeeps.add(new NotNode(pred).peephole());
diff --git a/chapter17/src/main/java/com/seaofnodes/simple/node/ShlNode.java b/chapter17/src/main/java/com/seaofnodes/simple/node/ShlNode.java
index b67d985a..6fd951e4 100644
--- a/chapter17/src/main/java/com/seaofnodes/simple/node/ShlNode.java
+++ b/chapter17/src/main/java/com/seaofnodes/simple/node/ShlNode.java
@@ -44,7 +44,7 @@ public class ShlNode extends Node {
             if( (shl.value()&63)==0 )
                 return lhs;
             // (x + c) << i  =>  (x << i) + (c << i)
-            if( lhs instanceof AddNode add && add.in(2)._type instanceof TypeInteger c && c.isConstant() && c!=TypeInteger.ZERO ) {
+            if( lhs instanceof AddNode add && add.addDep(this).in(2)._type instanceof TypeInteger c && c.isConstant() && c!=TypeInteger.ZERO ) {
                 long sum = c.value() << shl.value();
                 if( Integer.MIN_VALUE <= sum  && sum <= Integer.MAX_VALUE )
                     return new AddNode( new ShlNode(add.in(1),rhs).peephole(), Parser.con(sum) );
diff --git a/chapter17/src/main/java/com/seaofnodes/simple/node/StartNode.java b/chapter17/src/main/java/com/seaofnodes/simple/node/StartNode.java
index c03a4b06..d82030f8 100644
--- a/chapter17/src/main/java/com/seaofnodes/simple/node/StartNode.java
+++ b/chapter17/src/main/java/com/seaofnodes/simple/node/StartNode.java
@@ -44,6 +44,4 @@ public class StartNode extends CFGNode implements MultiNode {
     @Override void _walkUnreach( BitSet visit, HashSet<CFGNode> unreach ) { }
 
     @Override public int loopDepth() { return (_loopDepth=1); }
-
-    @Override public Node getBlockStart() { return this; }
 }
diff --git a/chapter17/src/main/java/com/seaofnodes/simple/node/StopNode.java b/chapter17/src/main/java/com/seaofnodes/simple/node/StopNode.java
index 0eacc1f4..5a02190a 100644
--- a/chapter17/src/main/java/com/seaofnodes/simple/node/StopNode.java
+++ b/chapter17/src/main/java/com/seaofnodes/simple/node/StopNode.java
@@ -84,6 +84,4 @@ public class StopNode extends CFGNode {
         GlobalCodeMotion.buildCFG(this);
         return this;
     }
-
-    @Override public Node getBlockStart() { return this; }
 }
diff --git a/chapter17/src/main/java/com/seaofnodes/simple/node/StoreNode.java b/chapter17/src/main/java/com/seaofnodes/simple/node/StoreNode.java
index 7b1bddd5..8e3e6693 100644
--- a/chapter17/src/main/java/com/seaofnodes/simple/node/StoreNode.java
+++ b/chapter17/src/main/java/com/seaofnodes/simple/node/StoreNode.java
@@ -42,9 +42,15 @@ public class StoreNode extends MemOpNode {
     public Type compute() {
         Type val = val()._type;
         TypeMem mem = (TypeMem)mem()._type; // Invariant
-        Type t = mem._alias==_alias
-            ? val.meet(mem._t)  // Meet into existing memory
-            : Type.BOTTOM;
+        Type t = Type.BOTTOM;               // No idea on field contents
+        // Same alias, lift val to the declared type and then meet into other fields
+        if( mem._alias == _alias ) {
+            // Update declared forward ref to the actual
+            if( _declaredType.isFRef() && val instanceof TypeMemPtr tmp && !tmp.isFRef() )
+                _declaredType = tmp;
+            val = val.join(_declaredType);
+            t = val.meet(mem._t);
+        }
         return TypeMem.make(_alias,t);
     }
 
diff --git a/chapter17/src/main/java/com/seaofnodes/simple/type/Type.java b/chapter17/src/main/java/com/seaofnodes/simple/type/Type.java
index 989eff9e..7467be79 100644
--- a/chapter17/src/main/java/com/seaofnodes/simple/type/Type.java
+++ b/chapter17/src/main/java/com/seaofnodes/simple/type/Type.java
@@ -179,6 +179,9 @@ public class Type {
      */
     public Type glb() { return _type==TCTRL ? XCONTROL : BOTTOM; }
 
+    // Is forward-reference
+    public boolean isFRef() { return false; }
+
     // ----------------------------------------------------------
 
     // Size in bits to hold an instance of this type.
diff --git a/chapter17/src/main/java/com/seaofnodes/simple/type/TypeMemPtr.java b/chapter17/src/main/java/com/seaofnodes/simple/type/TypeMemPtr.java
index ec059b8f..449bf89e 100644
--- a/chapter17/src/main/java/com/seaofnodes/simple/type/TypeMemPtr.java
+++ b/chapter17/src/main/java/com/seaofnodes/simple/type/TypeMemPtr.java
@@ -57,6 +57,8 @@ public class TypeMemPtr extends Type {
 
     @Override
     public TypeMemPtr glb() { return make(_obj.glb(),true); }
+    // Is forward-reference
+    @Override public boolean isFRef() { return _obj.isFRef(); }
     @Override public TypeMemPtr makeInit() { return NULLPTR; }
     @Override public Type nonZero() { return VOIDPTR; }
 
diff --git a/chapter17/src/main/java/com/seaofnodes/simple/type/TypeStruct.java b/chapter17/src/main/java/com/seaofnodes/simple/type/TypeStruct.java
index 4e4d1305..39011ce2 100644
--- a/chapter17/src/main/java/com/seaofnodes/simple/type/TypeStruct.java
+++ b/chapter17/src/main/java/com/seaofnodes/simple/type/TypeStruct.java
@@ -36,7 +36,7 @@ public class TypeStruct extends Type {
     public static final TypeStruct BOT = make("$BOT",new Field[0]);
     public static final TypeStruct TEST = make("test",new Field[]{Field.TEST});
     // Forward-ref version
-    public static TypeStruct make(String name) { return make(name, (Field[])null); }
+    public static TypeStruct makeFRef(String name) { return make(name, (Field[])null); }
 
     // Array
     public static TypeStruct makeAry(TypeInteger len, int lenAlias, Type body, int bodyAlias) {
@@ -47,8 +47,8 @@ public class TypeStruct extends Type {
     }
 
     // A pair of self-cyclic types
-    private static final TypeStruct S1F = make("S1");
-    private static final TypeStruct S2F = make("S2");
+    private static final TypeStruct S1F = makeFRef("S1");
+    private static final TypeStruct S2F = makeFRef("S2");
     public  static final TypeStruct S1  = make("S1", new Field[]{ Field.make("a", TypeInteger.BOT, -1, false), Field.make("s2",TypeMemPtr.make(S2F,false),-2, false) });
     private static final TypeStruct S2  = make("S2", new Field[]{ Field.make("b", TypeFloat  .BOT, -3, false), Field.make("s1",TypeMemPtr.make(S1F,false),-4, false) });
 
@@ -89,8 +89,8 @@ public class TypeStruct extends Type {
         // And the answer is: "don't ask".
         if( !_name.equals(that._name) )
             return BOT;         // It's a struct; that's about all we know
-        if( this._fields==null ) return this;
-        if( that._fields==null ) return that;
+        if( this._fields==null ) return that;
+        if( that._fields==null ) return this;
         if( _fields.length != that._fields.length ) return BOT;
         // Just do field meets
         Field[] flds = new Field[_fields.length];
@@ -132,6 +132,9 @@ public class TypeStruct extends Type {
         return true;
     }
 
+    // Is forward-reference
+    @Override public boolean isFRef() { return _fields==null; }
+
     @Override
     boolean eq(Type t) {
         TypeStruct ts = (TypeStruct)t; // Invariant
diff --git a/chapter17/src/test/java/com/seaofnodes/simple/BrainFuckTest.java b/chapter17/src/test/java/com/seaofnodes/simple/BrainFuckTest.java
index f7c66bda..0a48d2e7 100644
--- a/chapter17/src/test/java/com/seaofnodes/simple/BrainFuckTest.java
+++ b/chapter17/src/test/java/com/seaofnodes/simple/BrainFuckTest.java
@@ -12,7 +12,6 @@ import static org.junit.Assert.fail;
 
 public class BrainFuckTest {
 
-    @Ignore
     @Test
     public void testBrainfuck() {
         var program = "++++++++[>++++[>++>+++>+++>+<<<<-]>+>+>->>+[<]<-]>>.>---.+++++++..+++.>>.<-.<.+++.------.--------.>>+.>++.".getBytes(StandardCharsets.UTF_8);
@@ -32,9 +31,9 @@ u8[] output = new u8[0];
 while (pc < program#) {
     int command = program[pc];
     if (command == 62) {
-        d = d + 1;
+        d++;
     } else if (command == 60) {
-        d = d - 1;
+        d--;
     } else if (command == 43) {
         data[d] = data[d] + 1;
     } else if (command == 45) {
@@ -43,10 +42,8 @@ while (pc < program#) {
         u8[] old = output;
         output = new u8[output# + 1];
         int i = 0;
-        while (i < old#) {
-            output[i] = old[i];
-            i = i + 1;
-        }
+        while (i < old#)
+            output[i] = old[i++];
         output[i] = data[d];
     } else if (command == 44) {
         data[d] = 42;
@@ -54,24 +51,24 @@ while (pc < program#) {
         if (data[d] == 0) {
             int d = 1;
             while (d > 0) {
-                pc = pc + 1;
+                pc++;
                 command = program[pc];
-                if (command == 91) d = d + 1;
-                if (command == 93) d = d - 1;
+                if (command == 91) d++;
+                if (command == 93) d--;
             }
         }
     } else if (command == 93) {
-        if (data[d] != 0) {
+        if (data[d]) {
             int d = 1;
             while (d > 0) {
-                pc = pc - 1;
+                pc--;
                 command = program[pc];
-                if (command == 93) d = d + 1;
-                if (command == 91) d = d - 1;
+                if (command == 93) d++;
+                if (command == 91) d--;
             }
         }
     }
-    pc = pc + 1;
+    pc++;
 }
 return output;
                 """);
diff --git a/chapter17/src/test/java/com/seaofnodes/simple/Chapter06Test.java b/chapter17/src/test/java/com/seaofnodes/simple/Chapter06Test.java
index ff1f3251..6308bdea 100644
--- a/chapter17/src/test/java/com/seaofnodes/simple/Chapter06Test.java
+++ b/chapter17/src/test/java/com/seaofnodes/simple/Chapter06Test.java
@@ -84,7 +84,7 @@ else
     b=5;
 return b;""", TypeInteger.BOT);
         StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Region38,2,5);", stop.toString());
+        assertEquals("return Phi(Region36,2,5);", stop.toString());
     }
 
     @Test
@@ -200,7 +200,7 @@ if( arg ) {
 return a+b;
 """);
         StopNode ret = parser.parse().iterate();
-        assertEquals("return Phi(Region35,4,1);", ret.toString());
+        assertEquals("return Phi(Region32,4,1);", ret.toString());
     }
 
 
@@ -251,7 +251,7 @@ if( arg ) {
 return a+b+c;
 """);
         StopNode ret = parser.parse().iterate();
-        assertEquals("return (Phi(Region48,Phi(Region29,2,3),0)+Phi(Region,3,1));", ret.toString());
+        assertEquals("return (Phi(Region45,Phi(Region29,2,3),0)+Phi(Region,3,1));", ret.toString());
     }
 
 
diff --git a/chapter17/src/test/java/com/seaofnodes/simple/Chapter07Test.java b/chapter17/src/test/java/com/seaofnodes/simple/Chapter07Test.java
index b54c24a3..80cb15d4 100644
--- a/chapter17/src/test/java/com/seaofnodes/simple/Chapter07Test.java
+++ b/chapter17/src/test/java/com/seaofnodes/simple/Chapter07Test.java
@@ -36,7 +36,7 @@ if(arg){}else{
 return a;
 """);
         StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Region31,1,Phi(Loop18,1,(Phi_a+1)));", stop.toString());
+        assertEquals("return Phi(Region32,1,Phi(Loop18,1,(Phi_a+1)));", stop.toString());
     }
 
     @Test
@@ -56,7 +56,7 @@ while(i < arg) {
 return sum;
 """);
         StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Loop12,0,Phi(Loop26,Phi_sum,(Phi_sum+Phi(Loop,0,(Phi_j+1)))));", stop.toString());
+        assertEquals("return Phi(Loop12,0,Phi(Loop27,Phi_sum,(Phi_sum+Phi(Loop,0,(Phi_j+1)))));", stop.toString());
     }
 
     @Test
@@ -73,7 +73,7 @@ return b;
 """);
         Node._disablePeephole = true;
         StopNode stop = parser.parse();
-        assertEquals("return Phi(Loop12,2,Phi(Region34,Phi_b,4));", stop.toString());
+        assertEquals("return Phi(Loop12,2,Phi(Region35,Phi_b,4));", stop.toString());
         assertTrue(stop.ret().ctrl() instanceof CProjNode);
         Node._disablePeephole = false;
     }
@@ -93,7 +93,7 @@ while(a < 10) {
 return b;
 """);
         StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Loop12,2,(Phi(Region34,Phi_b,4)+1));", stop.toString());
+        assertEquals("return Phi(Loop12,2,(Phi(Region35,Phi_b,4)+1));", stop.toString());
         assertTrue(stop.ret().ctrl() instanceof CProjNode);
     }
 
diff --git a/chapter17/src/test/java/com/seaofnodes/simple/Chapter08Test.java b/chapter17/src/test/java/com/seaofnodes/simple/Chapter08Test.java
index c199b78c..5372388b 100644
--- a/chapter17/src/test/java/com/seaofnodes/simple/Chapter08Test.java
+++ b/chapter17/src/test/java/com/seaofnodes/simple/Chapter08Test.java
@@ -23,7 +23,7 @@ while(arg < 10) {
 return arg;
                 """);
         StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Region45,Phi(Region32,Phi(Loop10,arg,(Phi_arg+1)),Add),Add);", stop.toString());
+        assertEquals("return Phi(Region46,Phi(Region33,Phi(Loop10,arg,(Phi_arg+1)),Add),Add);", stop.toString());
         assertTrue(stop.ret().ctrl() instanceof RegionNode);
         Assert.assertEquals(5L, Evaluator.evaluate(stop, 1));
         Assert.assertEquals(10L, Evaluator.evaluate(stop, 6));
@@ -46,7 +46,7 @@ while(arg < 10) {
 return a;
                 """);
         StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Loop11,1,Phi(Region52,Phi_a,(Phi_a+1)));", stop.toString());
+        assertEquals("return Phi(Loop11,1,Phi(Region53,Phi_a,(Phi_a+1)));", stop.toString());
         assertTrue(stop.ret().ctrl() instanceof CProjNode);
     }
 
@@ -65,7 +65,7 @@ while(arg < 10) {
 return arg;
                 """);
         StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Region43,Phi(Loop10,arg,(Phi_arg+1)),Add);", stop.toString());
+        assertEquals("return Phi(Region44,Phi(Loop10,arg,(Phi_arg+1)),Add);", stop.toString());
         assertTrue(stop.ret().ctrl() instanceof RegionNode);
     }
 
@@ -81,7 +81,7 @@ while(arg < 10) {
 return arg;
                 """);
         StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Region32,Phi(Loop10,arg,(Phi_arg+1)),Add);", stop.toString());
+        assertEquals("return Phi(Region33,Phi(Loop10,arg,(Phi_arg+1)),Add);", stop.toString());
         assertTrue(stop.ret().ctrl() instanceof RegionNode);
     }
 
@@ -185,7 +185,7 @@ while(arg < 10) {
 return a;
 """);
         StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Region35,Phi(Loop11,1,(Phi_a+1)),Add);", stop.toString());
+        assertEquals("return Phi(Region36,Phi(Loop11,1,(Phi_a+1)),Add);", stop.toString());
         assertTrue(stop.ret().ctrl() instanceof RegionNode);
     }
 
diff --git a/chapter17/src/test/java/com/seaofnodes/simple/Chapter09Test.java b/chapter17/src/test/java/com/seaofnodes/simple/Chapter09Test.java
index b1d9d6e5..04ab8001 100644
--- a/chapter17/src/test/java/com/seaofnodes/simple/Chapter09Test.java
+++ b/chapter17/src/test/java/com/seaofnodes/simple/Chapter09Test.java
@@ -115,7 +115,7 @@ while (arg) {
 return arg;
                 """);
         StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Loop18,arg,(Phi_arg+1));", stop.toString());
+        assertEquals("return 0;", stop.toString());
     }
 
     @Test
@@ -283,7 +283,7 @@ return v1+v0;
     public void testFuzz8() {
         Parser parser = new Parser("while(arg) arg = arg - 1;  return arg;");
         StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Loop10,arg,(Phi_arg-1));", stop.toString());
+        assertEquals("return 0;", stop.toString());
     }
 
     @Test
diff --git a/chapter17/src/test/java/com/seaofnodes/simple/Chapter10Test.java b/chapter17/src/test/java/com/seaofnodes/simple/Chapter10Test.java
index 2a33031d..0bf921f6 100644
--- a/chapter17/src/test/java/com/seaofnodes/simple/Chapter10Test.java
+++ b/chapter17/src/test/java/com/seaofnodes/simple/Chapter10Test.java
@@ -245,7 +245,7 @@ while(arg) {
 return ret;
 """);
         StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Loop16,s0,Phi(Region43,s0,Phi_ret));", stop.toString());
+        assertEquals("return Phi(Loop16,s0,Phi(Region45,s0,Phi_ret));", stop.toString());
     }
 
     @Test
@@ -263,7 +263,7 @@ while(arg) {
 return ret;
 """);
         StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Loop20,s0,Phi(Region44,s0,Phi_ret));", stop.toString());
+        assertEquals("return Phi(Loop20,s0,Phi(Region46,s0,Phi_ret));", stop.toString());
     }
 
 
@@ -280,7 +280,7 @@ while(arg < 10) {
 return ret;
 """);
         StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Loop16,s0,Phi(Region41,s0,Phi_ret));", stop.toString());
+        assertEquals("return Phi(Loop16,s0,Phi(Region42,s0,Phi_ret));", stop.toString());
     }
 
     @Test
diff --git a/chapter17/src/test/java/com/seaofnodes/simple/Chapter11Test.java b/chapter17/src/test/java/com/seaofnodes/simple/Chapter11Test.java
index d6b7bb00..44814d53 100644
--- a/chapter17/src/test/java/com/seaofnodes/simple/Chapter11Test.java
+++ b/chapter17/src/test/java/com/seaofnodes/simple/Chapter11Test.java
@@ -324,7 +324,7 @@ while( prime <= arg ) {
 return primeCount;
 """);
         StopNode stop = parser.parse().iterate();
-        assertEquals("Stop[ return 0; return Phi(Loop23,1,Phi(Region100,Phi_primeCount,Phi(Region93,(Phi_primeCount+1),Phi_primeCount))); ]", stop.toString());
+        assertEquals("Stop[ return 0; return Phi(Loop23,1,Phi(Region102,Phi_primeCount,Phi(Region95,(Phi_primeCount+1),Phi_primeCount))); ]", stop.toString());
         assertEquals(0L, Evaluator.evaluate(stop,  1)); // No primes 1 or below
         assertEquals(1L, Evaluator.evaluate(stop,  2)); // 2
         assertEquals(2L, Evaluator.evaluate(stop,  3)); // 2, 3
@@ -476,7 +476,7 @@ while(arg) {
 return arg;
 """);
         StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Loop20,arg,Phi(Region48,.f,0));", stop.toString());
+        assertEquals("return 0;", stop.toString());
     }
 
     @Test
diff --git a/chapter17/src/test/java/com/seaofnodes/simple/Chapter14Test.java b/chapter17/src/test/java/com/seaofnodes/simple/Chapter14Test.java
index 7d7bb25a..e72b0c76 100644
--- a/chapter17/src/test/java/com/seaofnodes/simple/Chapter14Test.java
+++ b/chapter17/src/test/java/com/seaofnodes/simple/Chapter14Test.java
@@ -59,7 +59,7 @@ while( b ) b = b + 456;// Truncate
 return b;
 """);
         StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Loop11,123,((Phi_b+456)&255));", stop.toString());
+        assertEquals("return 0;", stop.toString());
     }
 
     @Test
diff --git a/chapter17/src/test/java/com/seaofnodes/simple/Chapter15Test.java b/chapter17/src/test/java/com/seaofnodes/simple/Chapter15Test.java
index d2d60b34..8161862f 100644
--- a/chapter17/src/test/java/com/seaofnodes/simple/Chapter15Test.java
+++ b/chapter17/src/test/java/com/seaofnodes/simple/Chapter15Test.java
@@ -50,7 +50,7 @@ return output;
 """);
         StopNode stop = parser.parse().iterate();
         assertEquals("return [u8];", stop.toString());
-        assertEquals("Obj<[u8]>{#=1,[]=[1]}", Evaluator.evaluate(stop,  0).toString());
+        assertEquals("\u0001", Evaluator.evaluate(stop,  0).toString());
     }
 
     @Test
diff --git a/chapter17/src/test/java/com/seaofnodes/simple/Chapter17Test.java b/chapter17/src/test/java/com/seaofnodes/simple/Chapter17Test.java
index 790f9531..91c275ce 100644
--- a/chapter17/src/test/java/com/seaofnodes/simple/Chapter17Test.java
+++ b/chapter17/src/test/java/com/seaofnodes/simple/Chapter17Test.java
@@ -10,12 +10,63 @@ public class Chapter17Test {
 
     @Test
     public void testJig() {
-        Parser parser = new Parser(
-"""
+        Parser parser = new Parser("""
 return 3.14;
 """);
         StopNode stop = parser.parse().iterate();
         assertEquals("return 3.14;", stop.toString());
         assertEquals(3.14, Evaluator.evaluate(stop,  0));
     }
+
+    @Test
+    public void testInc0() {
+        Parser parser = new Parser("""
+return arg++;
+""");
+        StopNode stop = parser.parse().iterate();
+        assertEquals("return arg;", stop.toString());
+        assertEquals(0L, Evaluator.evaluate(stop, 0));
+    }
+
+    @Test
+    public void testInc1() {
+        Parser parser = new Parser("""
+return arg+++arg++;
+""");
+        StopNode stop = parser.parse().iterate();
+        assertEquals("return ((arg*2)+1);", stop.toString());
+        assertEquals(1L, Evaluator.evaluate(stop, 0));
+    }
+
+    @Test
+    public void testInc2() {
+        Parser parser = new Parser("""
+//   -(arg--)-(arg--)
+return -arg---arg--;
+""");
+        StopNode stop = parser.parse().iterate();
+        assertEquals("return (-((arg*2)+-1));", stop.toString());
+        assertEquals(1L, Evaluator.evaluate(stop, 0));
+    }
+
+
+    @Test
+    public void testLinkedList2() {
+        Parser parser = new Parser("""
+struct LLI { LLI? next; int i; };
+LLI? head = null;
+while( arg-- )
+    head = new LLI { next=head; i=arg; };
+int sum=0;
+while( head ) {
+    sum = sum + head.i;
+    head = head.next;
+}
+return sum;
+""");
+        StopNode stop = parser.parse().iterate();
+        assertEquals("return Phi(Loop35,0,(Phi_sum+.i));", stop.toString());
+        assertEquals(45L, Evaluator.evaluate(stop, 10));
+    }
+
 }
diff --git a/chapter17/src/test/java/com/seaofnodes/simple/TypeTest.java b/chapter17/src/test/java/com/seaofnodes/simple/TypeTest.java
index 6f7409cd..03b0e31d 100644
--- a/chapter17/src/test/java/com/seaofnodes/simple/TypeTest.java
+++ b/chapter17/src/test/java/com/seaofnodes/simple/TypeTest.java
@@ -79,7 +79,7 @@ public class TypeTest {
 
     // Test theoretical properties.
     // This is a symmetric complete bounded (ranked) lattice.
-    // Also the meet is commutative and associative.
+    // Also, the meet is commutative and associative.
     // The lattice has a dual (symmetric), and join is ~(~x meet ~y).
     // See https://en.wikipedia.org/wiki/Lattice_(order).
     @Test
diff --git a/chapter17/src/test/java/com/seaofnodes/simple/evaluator/Evaluator.java b/chapter17/src/test/java/com/seaofnodes/simple/evaluator/Evaluator.java
index 28896283..c215de00 100644
--- a/chapter17/src/test/java/com/seaofnodes/simple/evaluator/Evaluator.java
+++ b/chapter17/src/test/java/com/seaofnodes/simple/evaluator/Evaluator.java
@@ -100,7 +100,7 @@ public class Evaluator {
         }
         @Override
         public String toString() {
-            if (struct._name.equals("u8[]")) {
+            if (struct._name.equals("[u8]")) {
                 var sb = new StringBuilder();
                 for (int i=struct._fields.length-1; i<fields.length; i++) {
                     var v = fields[i];