Chapter renumber, and split ch 17

Renumber chapters 10a, 10b, 11, 12, 13, 14 -> 10, 11, 13, 12, [11,14].
Split ch 17 into a 17a and 17b; shuffle around im/mutable syntax to be consistent, and present it more slowly.
THe new immutable syntax is pushed through all later chapters

8 files changed, 886 insertions, 771 deletions

diff --git a/chapter14/README.md b/chapter14/README.md
index 50009f4a..84207f52 100644
--- a/chapter14/README.md
+++ b/chapter14/README.md
@@ -1,27 +1,79 @@
-# Chapter 14: Narrow types
+# Chapter 14: Numeric Types
 
 [Previous: Chapter 13](../chapter13/README.md) |
 [Next: Chapter 15](../chapter15/README.md)
 
 # Table of Contents
 
-1. [Narrow Word Types](#narrow-or-sub-word-types)
-2. [Overflow handling](#overflow-handling)
-3. [Integer ranges](#integer-ranges)
-4. [Bitwise operations](#bitwise-operations)
-5. [Precedence](#precedence)
-6. [Type lattice](#type-implementation)
-7. [Nodes](#nodes)
+1. [Floating-point arithmetic](#floating-point-arithmetic)
+2. [Narrow Word Types](#narrow-or-sub-word-types)
+3. [Overflow handling](#overflow-handling)
+4. [Integer ranges](#integer-ranges)
+5. [Bitwise operations](#bitwise-operations)
+6. [Precedence](#precedence)
+7. [Type lattice](#type-implementation)
+8. [Nodes](#nodes)
 
 
-In this chapter, we add sub-word integer types.
+With structs, reference fields, and scheduling in place, this chapter extends
+the numeric values they carry. We add floating-point arithmetic, narrow
+integer and float types, and integer ranges.
 
 You can also read [this chapter](https://github.com/SeaOfNodes/Simple/tree/linear-chapter14) in a linear Git revision history on the [linear](https://github.com/SeaOfNodes/Simple/tree/linear) branch and [compare](https://github.com/SeaOfNodes/Simple/compare/linear-chapter13...linear-chapter14) it to the previous chapter.
 
-## Narrow or sub-word types
+## Floating-point arithmetic
+
+Floating point values start with the `flt` type and compute IEEE754 64-bit arithmetic.
+Integer expressions auto-widen to floats when involved in a float expression.
+
+```java
+flt f = 0.5;
+int x = 2;
+f = f+x;     // Auto-widen x to 2.0, result is 2.5
+f = f+true;  // Since bools are just synonyms for integers 0,1 they auto-widen also
+```
 
-Narrow or sub-word integer types refer to integer data types that occupy less memory (fewer bits) than the standard or "full-width" (typically 32 or 64 bits) integer types provided by a system or programming language.
+There is no corresponding way right now to round a `flt` back to an `int`:
+```java
+int x = 3.14; // error
+```
+
+Here is Newton's method for computing a square root:
+```java
+flt guess = arg;  // Initial guess is just argument
+while( true ) {
+    // Next guess from Newton's method
+    flt next = (arg/guess + guess)/2;
+    // Break if hit fixed point
+    if( next == guess ) break;
+    guess = next;
+}
+return guess;
+```
+When run with argument 2, produces 1.414213562373095.
 
+Floating point operations have their own Nodes:
+
+| Node                   | Op                   |
+|------------------------|----------------------|
+| AddF, SubF, MulF, DivF | Basic binary FP ops  |
+| MinusF                 | Unary negate         |
+| EQF, LTF, LEF          | FP compare operators |
+
+The parser uses [`Node.widen()`](src/main/java/com/seaofnodes/simple/node/Node.java)
+to choose the floating-point operation and insert `ToFloatNode` conversions.
+The float lattice has constants between `TOP` and `BOT`, like the integer
+lattice before ranges. [`TypeFloat`](src/main/java/com/seaofnodes/simple/type/TypeFloat.java)
+also records whether a value fits `f32`; assigning to `f32` rounds it to that
+precision. Conversion from float back to integer remains a separate, pending
+language feature.
+
+
+## Narrow or sub-word types
+
+Narrow or sub-word integer types refer to integer data types that occupy less
+memory (fewer bits) than the standard or "full-width" (typically 32 or 64 bits)
+integer types provided by a system or programming language.
 
 As a prelude to arrays, especially arrays of bytes common in all networking
 codes, Simple needs some way to manipulate sub-word integer types.
@@ -209,11 +261,11 @@ This is the same as regular additions:
 public long value() { assert isConstant(); return _min; }
 ```
 
-#### Truncate(2)
+#### More Truncate
 
 ```java
 u8 a = arg;  // arg & 255
-u8 b = arg;  // arg & 255(same as a)
+u8 b = arg;  // arg & 255 (same as a)
 u8 c = a + b; // (arg&255)*2, type = TypeInteger.BOT
 return c; // (((arg&255)*2)&255), type = TypeInteger.U8
 ```
@@ -224,9 +276,9 @@ on the expression to keep it in the valid boundaries.
 
 
 ## Integer ranges
-Link hacker's delight here.
 
-For range math, visit:[^1]
+For general range math, visit Hackers Delight:[^1]
+
 ## Bitwise operations
 We support the following bitwise operators:
 And `&`, Or `|`, Xor `^`, Shift left `<<`, Shift right `>>`, Shift right zero `>>>`
@@ -242,6 +294,8 @@ And `&`, Or `|`, Xor `^`, Shift left `<<`, Shift right `>>`, Shift right zero `>
 
 Note `>>>` is a logical shift and not an arithmetic shift.
 
+Here is a sample of peephole opts on these logical operations:
+
 ####  AndNode:
 
 ##### lhs & -1 = lhs;
@@ -305,7 +359,7 @@ arg + 123 & 3 = (arg + 123) & 3
 
 ## Type Implementation
 
-The ![Integer](../chapter10a/docs/type-integer.svg) `TypeInteger` class is
+The ![Integer](../chapter10/docs/type-integer.svg) `TypeInteger` class is
 reworked to support a full range of min/max values.  At this time, only some
 power-of-2 sized ranges are exposed to the programmer but the optimizer
 internally supports all ranges.  The MEET operation takes the min-of-mins and
@@ -321,17 +375,18 @@ Example: the `i8` type has the range `[-128...127]`.
 
 Example: the `dual` of `bool` is `[1...0]` (just swap min and max).
 
-The ![Float](../docs/type-float.svg) `TypeFloat` class is also reworked to support 32-bit and 64-bit sizes.
+The ![Float](../docs/type-float.svg) `TypeFloat` class introduced here supports
+both 32-bit and 64-bit sizes.
 
 The integer range diagram is schematic: it shows the boolean range and its
-dual as examples among the possible ranges. The other domains retain the
+dual as examples among the possible ranges.  The other domains retain the
 named structs, nullable pointers, and precise memory aliases from earlier chapters.
 
 ![Graph1](./docs/lattice.svg)
 
 ### meet:
 
-Meet of two ranges:
+The Meet of two ranges:
 ```java
 @Override
 public Type xmeet(Type other) {
@@ -340,17 +395,14 @@ TypeInteger i = (TypeInteger)other; // Contract
 return make(Math.min(_min,i._min), Math.max(_max,i._max));
 }
 ```
-Combine all values that could possibly occur within either range.
 
-## Nodes
-
-Added this Chapter are some bit-manipulation Nodes representing common hardware
-ops to mask, shift, sign-extend and round bits.  The truncation and extension
-logic uses these.  They are otherwise very similar to the previous
-`Add/Sub/Mul/Div` Nodes but with slightly different constant math and
-slightly different `idealize()` calls.
+This combines all values that could possibly occur within either range.
+Also, the implementation is trivial.
 
 
 
 [^1]:  Hacker's delight.
     4-2 Propagating Bounds through Adds and Subtracts
+
+The next chapter uses these numeric types for array lengths, indexing, and
+element storage, including byte arrays.
diff --git a/chapter14/chapter14.iml b/chapter14/chapter14.iml
new file mode 100644
index 00000000..4c719b6d
--- /dev/null
+++ b/chapter14/chapter14.iml
@@ -0,0 +1,28 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="false">
+    <output url="file://$MODULE_DIR$/../build/idea/production/chapter14" />
+    <output-test url="file://$MODULE_DIR$/../build/idea/test/chapter14" />
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/src/main/java" isTestSource="false" />
+      <sourceFolder url="file://$MODULE_DIR$/src/test/java" isTestSource="true" />
+      <excludeFolder url="file://$MODULE_DIR$/build" />
+      <excludeFolder url="file://$MODULE_DIR$/target" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+    <orderEntry type="module" module-name="graph" />
+    <orderEntry type="module" module-name="print" />
+    <orderEntry type="module-library" scope="TEST">
+      <library name="JUnit4">
+        <CLASSES>
+          <root url="jar://$MODULE_DIR$/lib/junit-4.12.jar!/" />
+          <root url="jar://$MODULE_DIR$/lib/hamcrest-core-1.3.jar!/" />
+        </CLASSES>
+        <JAVADOC />
+        <SOURCES />
+      </library>
+    </orderEntry>
+  </component>
+</module>
diff --git a/chapter14/src/main/java/com/seaofnodes/simple/type/TypeStruct.java b/chapter14/src/main/java/com/seaofnodes/simple/type/TypeStruct.java
index 2599a383..8ad59a39 100644
--- a/chapter14/src/main/java/com/seaofnodes/simple/type/TypeStruct.java
+++ b/chapter14/src/main/java/com/seaofnodes/simple/type/TypeStruct.java
@@ -8,14 +8,12 @@ import java.util.ArrayList;
  */
 public class TypeStruct extends Type {
 
-    // A Struct has a name and a set of fields; the fields themselves have
-    // names and types.  Briefly during parsing its allowed to have a
-    // forward-ref to a Struct; in this case the _fields array is null.
-    // Its illegal to attempt to load a field from a forward-ref struct.
-    //
-    // During the normal optimization run, struct types "bottom out" at further
-    // struct references, so we don't have to handle e.g.  cyclic types.  The
-    // "bottom out" is again the forward-ref struct.
+    // Immutable shallow references, resolved by name in Parser.TYPES when needed.
+    // A name-only struct has _fields == null, even after its definition is known.
+    // For LLI { LLI? next; int i; }, L0 is name-only and L1.next points to L0;
+    // TYPES["LLI"] holds L1. We deliberately stop recursive type expansion here,
+    // keeping interning and lattice operations finite and acyclic. Never patch
+    // L0 into L1: field access looks up the complete declaration by name instead.
     public final String _name;
     public final Field[] _fields;
 
diff --git a/chapter14/src/test/java/com/seaofnodes/simple/Chapter10bTest.java b/chapter14/src/test/java/com/seaofnodes/simple/Chapter10bTest.java
deleted file mode 100644
index 6f094cfb..00000000
--- a/chapter14/src/test/java/com/seaofnodes/simple/Chapter10bTest.java
+++ /dev/null
@@ -1,64 +0,0 @@
-package com.seaofnodes.simple;
-
-import com.seaofnodes.simple.node.*;
-import com.seaofnodes.simple.evaluator.Evaluator;
-import org.junit.Test;
-import static org.junit.Assert.*;
-
-public class Chapter10bTest {
-    @Test public void testIndependentField() {
-        var stop = new Parser("""
-            struct S { int x; int y; }
-            S s = new S;
-            s.x = 42;
-            while (arg > 0) { s.y = s.y + arg; arg = arg - 1; }
-            return s.x;
-            """).parse().iterate();
-        assertEquals("return 42;",stop.toString());
-        assertEquals(42L,Evaluator.evaluate(stop,5));
-        assertNull(stop.walk(n -> n instanceof LoadNode ? n : null));
-    }
-
-    @Test public void testParallelMemoryPhis() {
-        var stop = new Parser("""
-            struct S { int x; int y; int z; }
-            S a = new S; S b = new S;
-            S p = a; if (arg) p = b;
-            while (arg > 0) {
-                a.x = p.x + arg;
-                a.y = p.y + 2;
-                a.z = p.z + 3;
-                arg = arg - 1;
-            }
-            return a;
-            """).parse().iterate();
-        int[] phis = {0};
-        stop.walk(n -> {
-            if (n instanceof MemPhiNode) phis[0]++;
-            if (n instanceof MemMergeNode m && m.in(1) instanceof BulkMemPhiNode b)
-                for(int a=b._aliases.nextSetBit(0); a>=0; a=b._aliases.nextSetBit(a+1))
-                    assertTrue(a<m.nIns() && m.in(a)!=null);
-            assertFalse(n instanceof PhiNode && n.isMem() &&
-                !(n instanceof MemPhiNode) && !(n instanceof BulkMemPhiNode));
-            return null;
-        });
-        assertTrue(phis[0]>=3);
-        assertArrayEquals(new Object[]{1L,2L,3L},((Evaluator.Obj)Evaluator.evaluate(stop,4)).fields());
-    }
-
-    @Test public void testLateSliceWorklist() throws ReflectiveOperationException {
-        // Seed 97 exposed a store selecting a bulk predecessor without queuing
-        // it. Keep both the worklist assertion and the final heap check.
-        for (int seed : new int[]{0,97,123,456}) {
-            var parser = new Parser(Chapter10Test.NESTED_MEMORY);
-            var field = IterPeeps.class.getDeclaredField("WORK");
-            field.setAccessible(true);
-            Object work = field.get(null);
-            field = work.getClass().getDeclaredField("_R");
-            field.setAccessible(true);
-            ((java.util.Random)field.get(work)).setSeed(seed);
-            var stop = parser.parse().iterate();
-            assertArrayEquals(new Object[]{9L,25L,17L},((Evaluator.Obj)Evaluator.evaluate(stop,4)).fields());
-        }
-    }
-}
diff --git a/chapter14/src/test/java/com/seaofnodes/simple/Chapter11Test.java b/chapter14/src/test/java/com/seaofnodes/simple/Chapter11Test.java
index d2e300b1..5f92c9c1 100644
--- a/chapter14/src/test/java/com/seaofnodes/simple/Chapter11Test.java
+++ b/chapter14/src/test/java/com/seaofnodes/simple/Chapter11Test.java
@@ -1,532 +1,64 @@
 package com.seaofnodes.simple;
 
-
+import com.seaofnodes.simple.node.*;
 import com.seaofnodes.simple.evaluator.Evaluator;
-import com.seaofnodes.simple.node.StopNode;
 import org.junit.Test;
-
-
-import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.*;
 
 public class Chapter11Test {
-
-    // A placeholder test used to rapidly rotate through fuzzer produced issues
-    @Test
-    public void testFuzzer() {
-        Parser parser = new Parser(
-"""
-while(-----arg) {
-    while(-arg) {
-        while(-----arg*---0) {
-                int N=--false==false<--arg;
-                while(N<-4==N) {
-                    N=N+N;
-                }
-            }
-        {
-            int kzEl_r7EYz=3*----0!=-arg<(37*--97!=0/arg==arg)<=-(--arg!=0);
-            while(kzEl_r7EYz<---1) {
-                kzEl_r7EYz=kzEl_r7EYz+kzEl_r7EYz*arg>=24;
-                if(7) continue;
-                kzEl_r7EYz=false;
-                if(-kzEl_r7EYz+arg<-3) continue;
-                else {
-                    while(kzEl_r7EYz) continue;
-                    arg=----3;
-                    kzEl_r7EYz=-(-----arg*1>-kzEl_r7EYz);
-                    int v2uF_4ba=9;
-                }
-            }
-        }
-        int pjcp7rv=arg;
-        {
-            int m2ya3=--arg-pjcp7rv;
-            while(m2ya3<-----pjcp7rv>=pjcp7rv+--pjcp7rv!=---pjcp7rv!=-arg<---(-m2ya3)>m2ya3<=-----true>14!=--m2ya3) {
-                m2ya3=m2ya3+-(--0<=false<pjcp7rv/arg<=-true);
-                while((--m2ya3)<--arg<-----arg*false!=arg<pjcp7rv*arg) {
-                    pjcp7rv=-3+-arg;
-                    break;
-                }
-                while(-3) {
-                    while(67+0-61) m2ya3=m2ya3;
-                    if(----pjcp7rv==---(---arg)) pjcp7rv=0!=-23;
-                    else pjcp7rv=----89;
-                    while(m2ya3!=m2ya3<pjcp7rv) m2ya3=1;
-                    while(--arg<=pjcp7rv) pjcp7rv=-32<=-m2ya3+62;
-                }
-                break;
-            }
-        }
-        {
-            int arg=-1<-9!=(-arg>=-pjcp7rv>=arg<=arg);
-            while(arg<-arg) {
-                arg=arg+--arg;
-                {
-                    while((--93)--pjcp7rv*-pjcp7rv+arg) arg=0-(6>=(--(---41/(0))!=--pjcp7rv)>=---2*33);
-                    pjcp7rv=11;
-                    int c=pjcp7rv;
-                    if(--107) break;
-                    else break;
-                }
-            }
-        }
-        pjcp7rv=pjcp7rv;
-        int aR0Wkua=-pjcp7rv==pjcp7rv;
-        {
-            if(-0!=-0) while(-true) break;
-            else {
-                while(aR0Wkua) pjcp7rv=-0/pjcp7rv;
-                pjcp7rv=pjcp7rv;
-            }
-        }
-    }
-    if(-arg) {
-        {
-            int Isdlt0fr91=0!=arg;
-            while(Isdlt0fr91<-Isdlt0fr91==-Isdlt0fr91+true) {
-                Isdlt0fr91=Isdlt0fr91+-1!=true;
-                if(-arg) if(--arg<=Isdlt0fr91) Isdlt0fr91=-Isdlt0fr91;
-                int i=---arg<---arg!=--40;
-                {
-                    int jVX43Ln4Dm=-(6)==-Isdlt0fr91/----0;
-                    while(jVX43Ln4Dm<--(3-3)) {
-                        jVX43Ln4Dm=jVX43Ln4Dm+-0<25;
-                        i=24<--(jVX43Ln4Dm);
-                    }
-                }
-                i=(arg!=----false>=7);
-                int Te=5>-arg;
-                break;
-            }
-        }
-        arg=arg!=--true/arg;
-        {
-            int UX=arg;
-            while(UX<-3*arg) {
-                UX=UX+arg/-1;
-                arg=-3--(-UX--47<arg==--arg==arg)/arg--UX>=-arg;
-                if(---12) while(-UX) break;
-                break;
-            }
-        }
-        continue;
-    }
-    if(arg) arg=--0;
-    else if(1) continue;
-    int DtTlhjYq=19==arg;
-    {
-        arg=--DtTlhjYq<=(DtTlhjYq/---DtTlhjYq<=-DtTlhjYq);
-        if(---arg) continue;
-        else {
-                int Zsl=40;
-                while(Zsl<--Zsl--false>((Zsl))==Zsl!=--DtTlhjYq-DtTlhjYq-DtTlhjYq) {
-                    Zsl=Zsl+arg;
-                }
-            }
-        if((arg)) if(-DtTlhjYq) {
-            }
-            else while(((2)==3*arg/DtTlhjYq)<=0==---arg) return false;
-        else {
-                int lwbF=arg>=0;
-                while(lwbF<57) {
-                    lwbF=lwbF+--(-arg+lwbF)>=-2>=arg!=arg;
-                    arg=----0+0;
-                    while(49) break;
-                    if(true) DtTlhjYq=-----arg;
-                    DtTlhjYq=0!=-----(0);
-                }
-            }
-        arg=---arg!=DtTlhjYq/--0;
-        DtTlhjYq=-DtTlhjYq/(--arg<arg);
-        if(32) {
-                int q=-DtTlhjYq;
-                while(q<arg*(0*q)/0) {
-                    q=q+DtTlhjYq;
-                    DtTlhjYq=arg;
-                }
-            }
-        else if(--arg) if(15) break;
-                else arg=0==arg<=-55>DtTlhjYq;
-            else {
-            }
-        DtTlhjYq=-0;
-        {
-            while((0)<-arg) DtTlhjYq=-DtTlhjYq;
-        }
-        if(30/--(arg)>=0) DtTlhjYq=-0>=arg;
-        else {
-            int Y2wcIQJ=--DtTlhjYq*---11;
-            if(arg==arg) {
-                Y2wcIQJ=-----Y2wcIQJ;
-                Y2wcIQJ=Y2wcIQJ<7;
-                if(DtTlhjYq) arg=arg;
-                else break;
-                while(-arg!=-31==(false<=-15>=-DtTlhjYq+--6*-----Y2wcIQJ<=---arg!=-Y2wcIQJ<=---0<-arg*--Y2wcIQJ)) DtTlhjYq=arg!=3;
-            }
-            continue;
-        }
-        arg=DtTlhjYq;
-        arg=--3/(---arg)>=80>=-DtTlhjYq<=DtTlhjYq;
-        arg=51+---(-true)!=arg!=----1==-DtTlhjYq;
-        if(11<=arg) if((arg)+79<32+(-arg)) continue;
-            else if(true==DtTlhjYq) break;
-        break;
-    }
-}
-if(arg!=62==arg) {
-    while(---arg) {
-        {
-            int bhmDacPM=arg/arg;
-            while(bhmDacPM<arg) {
-                bhmDacPM=bhmDacPM+80*((-bhmDacPM)/---bhmDacPM>1)<bhmDacPM-2!=7;
-                arg=-0;
-                arg=bhmDacPM>=-arg+-arg;
-                break;
-            }
-        }
-        int arg=true;
-        arg=arg<=arg;
-        {
-            int KlC=30;
-            while(KlC<-2) {
-                KlC=KlC+-1!=25<=-KlC>KlC>----0;
-                int Ij=arg>=-arg<=---10;
-                {
-                    int LAbgurVa2R=-arg!=Ij;
-                    while(LAbgurVa2R<-true) {
-                        LAbgurVa2R=LAbgurVa2R+Ij;
-                        KlC=-LAbgurVa2R;
-                        Ij=42*(-Ij>true);
-                        while(Ij) arg=KlC;
-                        KlC=-----7>-(--KlC<--7)==-LAbgurVa2R;
-                    }
-                }
-                int a=Ij<=-KlC;
-                if(Ij) {
-                    int r1W=a!=-false;
-                }
-                else {
-                    arg=56>=Ij;
-                    while(54) break;
-                    arg=8>=-(a<--Ij)/a>=-a-KlC;
-                }
-                int Yt_T=KlC;
-                arg=KlC;
-            }
+    @Test public void testIndependentField() {
+        var stop = new Parser("""
+            struct S { int x; int y; }
+            S s = new S;
+            s.x = 42;
+            while (arg > 0) { s.y = s.y + arg; arg = arg - 1; }
+            return s.x;
+            """).parse().iterate();
+        assertEquals("return 42;",stop.toString());
+        assertEquals(42L,Evaluator.evaluate(stop,5));
+        assertNull(stop.walk(n -> n instanceof LoadNode ? n : null));
+    }
+
+    @Test public void testParallelMemoryPhis() {
+        var stop = new Parser("""
+            struct S { int x; int y; int z; }
+            S a = new S; S b = new S;
+            S p = a; if (arg) p = b;
+            while (arg > 0) {
+                a.x = p.x + arg;
+                a.y = p.y + 2;
+                a.z = p.z + 3;
+                arg = arg - 1;
+            }
+            return a;
+            """).parse().iterate();
+        int[] phis = {0};
+        stop.walk(n -> {
+            if (n instanceof MemPhiNode) phis[0]++;
+            if (n instanceof MemMergeNode m && m.in(1) instanceof BulkMemPhiNode b)
+                for(int a=b._aliases.nextSetBit(0); a>=0; a=b._aliases.nextSetBit(a+1))
+                    assertTrue(a<m.nIns() && m.in(a)!=null);
+            assertFalse(n instanceof PhiNode && n.isMem() &&
+                !(n instanceof MemPhiNode) && !(n instanceof BulkMemPhiNode));
+            return null;
+        });
+        assertTrue(phis[0]>=3);
+        assertArrayEquals(new Object[]{1L,2L,3L},((Evaluator.Obj)Evaluator.evaluate(stop,4)).fields());
+    }
+
+    @Test public void testLateSliceWorklist() throws ReflectiveOperationException {
+        // Seed 97 exposed a store selecting a bulk predecessor without queuing
+        // it. Keep both the worklist assertion and the final heap check.
+        for (int seed : new int[]{0,97,123,456}) {
+            var parser = new Parser(Chapter10Test.NESTED_MEMORY);
+            var field = IterPeeps.class.getDeclaredField("WORK");
+            field.setAccessible(true);
+            Object work = field.get(null);
+            field = work.getClass().getDeclaredField("_R");
+            field.setAccessible(true);
+            ((java.util.Random)field.get(work)).setSeed(seed);
+            var stop = parser.parse().iterate();
+            assertArrayEquals(new Object[]{9L,25L,17L},((Evaluator.Obj)Evaluator.evaluate(stop,4)).fields());
         }
-        if(----false/--arg/12+-----0) if(-9+-arg) while(arg!=(arg)) arg=--1>=-71-arg!=---(--arg*11+102)/--arg;
-            else if(----arg) continue;
-        if(-arg-arg) {
-            arg=-(-arg)*--(-3)<(-7==-arg----arg);
-            {
-                int arg=arg;
-                while(arg<-0>arg==-arg-(-arg>1+11)) {
-                    arg=arg+6-arg!=--0>---30>=---arg<=arg/(3)+---arg;
-                }
-            }
-            arg=-arg+arg;
-            arg=--47+-arg<1>arg*(-arg==-arg--0>3);
-            arg=(----arg)!=arg+--59;
-            arg=--4+arg==-(arg)-arg;
-        }
-        else {
-            while(--true-----true*-25+-18>arg>=-----(-arg)---13) {
-                arg=-0+--true<false;
-                continue;
-            }
-            arg=true<=arg;
-            break;
-        }
-        arg=arg*22<--(0+-arg);
-        {
-            continue;
-        }
-    }
-    arg=1*---((3<=true)==---2);
-    arg=7+-(-1);
-    return arg+--true;
-}
-else {
-    int o3ypEsewxM=-(---arg);
-    int vzXB=(-(---11<=--o3ypEsewxM>=--0))<=-0/-arg;
-    int L=-arg;
-    int B4mHcrf=---vzXB;
-    int oZWGdzZl=-o3ypEsewxM;
-    int K6tQqa1=11;
-    while(0!=--L) {
-            int sdZfTM=vzXB*true+K6tQqa1;
-            while(sdZfTM<false) {
-                sdZfTM=sdZfTM+arg;
-                sdZfTM=oZWGdzZl;
-                K6tQqa1=-K6tQqa1;
-                arg=---K6tQqa1;
-                while((3+-K6tQqa1)<oZWGdzZl) {
-                    if(-----(-1)) sdZfTM=-false;
-                    {}
-                }
-                K6tQqa1=vzXB!=-(B4mHcrf+-7>false);
-                sdZfTM=vzXB;
-            }
-        }
-    L=false;
-    while(31) B4mHcrf=arg;
-    oZWGdzZl=-0<--oZWGdzZl<=--2;
-    if(K6tQqa1>=20<=46) {
-        if(-1+-L) if(oZWGdzZl) {
-                int wmhv=-----0;
-            }
-        int arg=0;
-        o3ypEsewxM=---(oZWGdzZl);
-        return -oZWGdzZl/0;
-    }
-    else if(arg) {
-            int yKk5=B4mHcrf>=4>K6tQqa1<-B4mHcrf/o3ypEsewxM;
-            return -K6tQqa1;
-        }
-        else {
-            if(---0) {
-                {}
-                {}
-            }
-            return o3ypEsewxM;
-        }
-}
-""");
-        StopNode stop = parser.parse().iterate();
-        assertEquals("Stop[ return 9; return 0; return 0; return 0; ]", stop.toString());
-    }
-
-
-    @Test
-    public void testPrimes() {
-        Parser parser = new Parser(
-"""
-if( arg < 2 ) return 0;
-int primeCount = 1;
-int prime = 3;
-while( prime <= arg ) {
-    int isPrime = 1;
-    // Check for even case, so the next loop need only check odds
-    if( (prime/2)*2 == prime )
-        continue;
-    // Check odds up to sqrt of prime
-    int j = 3;
-    while( j*j <= prime ) {
-        if( (prime/j)*j == prime ) {
-            isPrime = 0;
-            break;
-        }
-        j = j + 2;
-    }
-    if( isPrime )
-        primeCount = primeCount + 1;
-    prime = prime + 2;
-}
-return primeCount;
-""");
-        StopNode stop = parser.parse().iterate();
-        assertEquals("Stop[ return 0; return Phi(Loop21,1,Phi(Region88,Phi_primeCount,Phi(Region82,(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
-        assertEquals(2L, Evaluator.evaluate(stop,  4)); // 2, 3
-        assertEquals(3L, Evaluator.evaluate(stop,  5)); // 2, 3, 5
-        assertEquals(4L, Evaluator.evaluate(stop, 10)); // 2, 3, 5, 7
-    }
-
-    @Test
-    public void testAntiDeps1() {
-        Parser parser = new Parser(
-"""
-struct S { int f; }
-S v=new S;
-v.f = 2;
-int i=new S.f;
-i=v.f;
-if (arg) v.f=1;
-return i;
-""");
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return .f;", stop.toString());
-    }
-
-    @Test
-    public void testAntiDeps2() {
-        Parser parser = new Parser(
-"""
-struct S { int f; }
-S v = new S;
-S t = new S;
-int i = 0;
-if (arg) {
-    if (arg+1) v = t;
-    i = v.f;
-} else {
-    v.f = 2;
-}
-return i;
-""");
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Region37,.f,0);", stop.toString());
-    }
-
-    @Test
-    public void testAntiDeps3() {
-        Parser parser = new Parser(
-"""
-struct S { int f; }
-S v0 = new S;
-S? v1;
-if (arg) v1 = new S;
-if (v1) {
-    v0.f = v1.f;
-} else {
-    v0.f = 2;
-}
-return v0;
-""");
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return new S;", stop.toString());
-    }
-
-
-    @Test
-    public void testAntiDeps4() {
-        Parser parser = new Parser(
-"""
-struct S { int f; }
-S v = new S;
-S t = new S;
-int i = v.f;
-if (arg+1) arg= 0;
-while (arg) v.f = 2;
-return i;
-""");
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return .f;", stop.toString());
-    }
-
-    @Test
-    public void testAntiDeps5() {
-        Parser parser = new Parser(
-"""
-struct S { int f; }
-S v = new S;
-while(1) {
-    while(arg+1) { arg=arg-1; }
-    if (arg) break;
-    v.f = 2;
-}
-return v;
-""");
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return new S;", stop.toString());
-    }
-
-    @Test
-    public void testAntiDeps6() {
-        Parser parser = new Parser(
-"""
-struct s { int v; }
-s ptr=new s;
-while( -arg )
-  ptr = new s;
-while(1)
-  arg = arg+ptr.v;
-""");
-        StopNode stop = parser.parse().iterate();
-        assertEquals("Stop[ return 0; return 0; ]", stop.toString());
-    }
-
-    @Test
-    public void testAntiDeps7() {
-        Parser parser = new Parser(
-"""
-struct S { int f; }
-S v = new S;
-S t = new S;
-int i = v.f;
-while (arg) {
-    v.f = arg;
-    arg = arg-1;
-}
-return i;
-""");
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return .f;", stop.toString());
-    }
-
-    @Test
-    public void testAntiDeps8() {
-        Parser parser = new Parser(
-"""
-struct S { int f; }
-S v = new S;
-S t = new S;
-while(arg) {
-    arg=arg-1;
-    int f = v.f;
-    v.f = 2;
-    if (arg) arg = f;
-    else v.f = 3;
-}
-return arg;
-""");
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Loop17,arg,Phi(Region41,.f,0));", stop.toString());
-    }
-
-    @Test
-    public void testAntiDeps9() {
-        Parser parser = new Parser(
-"""
-struct S { int f; }
-S v = new S;
-S t = new S;
-if (arg) {
-    v.f=2;
-    int i=t.f;
-    v.f=i;
-}
-return v;
-""");
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return new S;", stop.toString());
-    }
-
-    @Test
-    public void testExample2() {
-        Parser parser = new Parser(
-                """
-struct S { int f; }
-S v = new S;
-int i = arg;
-while (arg > 0) {
-    int j = i/3;
-    if (arg == 5)
-        v.f = j;
-    arg = arg - 1;
-}
-return v;
-                """);
-        StopNode stop = parser.parse().iterate();
-        //assertEquals("return new S;", stop.toString());
-    }
-
-    @Test
-    public void testSplit() {
-        Parser parser = new Parser(
-                                   """
-struct S { int f; }
-S s = new S;
-if( arg==0 ) s.f = 1;
-else if (arg == 1) s.f = 1;
-return s.f;
-""");
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Region43,1,Phi(Region38,1,0));", stop.toString());
-        assertEquals(1L, Evaluator.evaluate(stop,  0));
-        assertEquals(1L, Evaluator.evaluate(stop,  1));
-        assertEquals(0L, Evaluator.evaluate(stop,  2));
     }
 }
diff --git a/chapter14/src/test/java/com/seaofnodes/simple/Chapter12Test.java b/chapter14/src/test/java/com/seaofnodes/simple/Chapter12Test.java
index 998053ec..e84da36a 100644
--- a/chapter14/src/test/java/com/seaofnodes/simple/Chapter12Test.java
+++ b/chapter14/src/test/java/com/seaofnodes/simple/Chapter12Test.java
@@ -2,82 +2,221 @@ package com.seaofnodes.simple;
 
 import com.seaofnodes.simple.evaluator.Evaluator;
 import com.seaofnodes.simple.node.StopNode;
+import com.seaofnodes.simple.type.TypeStruct;
+import com.seaofnodes.simple.type.TypeMemPtr;
 import org.junit.Ignore;
 import org.junit.Test;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.fail;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertSame;
 
 public class Chapter12Test {
-    @Test public void testSubZeroFloat() {
-        var stop = new Parser("flt x = arg; return 0-x;").parse().iterate();
-        // Compare strings so +0.0 and -0.0 remain distinct.
-        assertEquals("0.0", Evaluator.evaluate(stop,0).toString());
-        assertEquals("-1.0", Evaluator.evaluate(stop,1).toString());
+    @Test
+    public void testJig() {
+        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 testDeadNumericReturns() {
-        for( String[] test : new String[][] {
-            {"if(1) return 7; else return 2.5;", "7"},
-            {"if(0) return 7; else return 2.5;", "2.5"},
-            {"return 7; return 2.5;", "7"},
-            {"return 2.5; return 7;", "2.5"}
-        } ) {
-            String src = test[0];
-            var stop = new Parser(src).parse().iterate();
-            assertEquals(src,test[1],com.seaofnodes.simple.evaluator.Evaluator.evaluate(stop,0).toString());
-        }
+    @Test
+    public void testLinkedList0() {
+        Parser parser = new Parser(
+"""
+struct LLI { LLI? next; int i; }
+LLI? head = null;
+while( arg ) {
+    LLI x = new LLI;
+    x.next = head;
+    x.i = arg;
+    head = x;
+    arg = arg-1;
+}
+return head.next.i;
+""");
+        try { parser.parse().iterate(); fail(); }
+        catch( Exception e ) { assertEquals("Might be null accessing 'i'",e.getMessage()); }
+    }
+
+    @Test
+    public void testLinkedList1() {
+        Parser parser = new Parser(
+"""
+struct LLI { LLI? next; int i; }
+LLI? head = null;
+while( arg ) {
+    LLI x = new LLI;
+    x.next = head;
+    x.i = arg;
+    head = x;
+    arg = arg-1;
+}
+if( !head ) return 0;
+LLI? next = head.next;
+if( next==null ) return 1;
+return next.i;
+""");
+        StopNode stop = parser.parse().iterate();
+        assertEquals("Stop[ return 0; return 1; return .i; ]", stop.toString());
+        assertEquals(2L, Evaluator.evaluate(stop,  3));
     }
 
+    @Test
+    public void testCoRecur() {
+        Parser parser = new Parser(
+"""
+struct int0 { int i; flt0? f; }
+struct flt0 { flt f; int0? i; }
+int0 i0 = new int0;
+i0.i = 17;
+flt0 f0 = new flt0;
+f0.f = 3.14;
+i0.f = f0;
+f0.i = i0;
+return f0.i.f.i.i;
+""");
+        StopNode stop = parser.parse().iterate();
+        assertEquals("return 17;", stop.toString());
+    }
 
     @Test
-    public void testJig() {
+    public void testNullRef0() {
         Parser parser = new Parser(
 """
-return 3.14;
+struct N { N next; int i; }
+N n = new N;
+return n.next;
 """);
         StopNode stop = parser.parse().iterate();
-        assertEquals("return 3.14;", stop.toString());
-        assertEquals(3.14, Evaluator.evaluate(stop,  0));
+        assertEquals("return null;", stop.toString());
     }
 
     @Test
-    public void testFloat() {
+    public void testNullRef1() {
         Parser parser = new Parser(
 """
-return 3.14;
+struct N { N next; int i; }
+N n = new N;
+n.next = new N;
+return n.next;
 """);
         StopNode stop = parser.parse().iterate();
-        assertEquals("return 3.14;", stop.toString());
-        assertEquals(3.14, Evaluator.evaluate(stop,  0));
+        assertEquals("return new N;", stop.toString());
     }
 
     @Test
-    public void testSquareRoot() {
+    public void testNullRef2() {
         Parser parser = new Parser(
 """
-flt guess = arg;
-while( 1 ) {
-    flt next = (arg/guess + guess)/2;
-    if( next == guess ) break;
-    guess = next;
-}
-return guess;
+struct N { N next; int i; }
+N n = new N;
+n.next = null;
+return n.next;
+""");
+        try { parser.parse().iterate(); fail(); }
+        catch( Exception e ) { assertEquals("Cannot store null into field *N next",e.getMessage()); }
+    }
+
+    @Test
+    public void testNullRef3() {
+        Parser parser = new Parser(
+"""
+struct N { N next; int i; }
+N n = new N;
+n.i = 3.14;
+return n.i;
+""");
+        try { parser.parse().iterate(); fail(); }
+        catch( Exception e ) { assertEquals("Cannot store 3.14 into field int i",e.getMessage()); }
+    }
+
+    @Test
+    public void testNullRef4() {
+        Parser parser = new Parser("-null-5/null-5");
+        try { parser.parse().iterate(); fail(); }
+        catch( Exception e ) { assertEquals("Expected an identifier, found 'null'",e.getMessage()); }
+    }
+
+    @Test public void testNullRef5() {
+        Parser parser = new Parser("return null+42;");
+        try { parser.parse().iterate(); fail(); }
+        catch( Exception e ) { assertEquals("Cannot 'Add' null",e.getMessage()); }
+    }
+
+    @Test
+    public void testEmpty() {
+        Parser parser = new Parser(
+"""
+struct S{};
 """);
         StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Loop10,(flt)arg,(((ToFloat/Phi_guess)+Phi_guess)/2.0));", stop.toString());
-        assertEquals(3.0, Evaluator.evaluate(stop,  9));
-        assertEquals(1.414213562373095, Evaluator.evaluate(stop,  2));
+        assertEquals("return 0;", stop.toString());
+        assertEquals(0L, Evaluator.evaluate(stop,  0));
+    }
+
+    @Test
+    public void testForwardRef0() {
+        Parser parser = new Parser(
+"""
+struct S1 { S2 s; }
+return new S2;
+""");
+        try { parser.parse().iterate(); fail(); }
+        catch( Exception e ) { assertEquals("Unknown struct type 'S2'",e.getMessage()); }
     }
 
     @Test
-    public void testFPOps() {
+    public void testForwardRef1() {
         Parser parser = new Parser(
 """
-flt x = arg;
-return x+1==x;
+struct S1 { S2? s; }
+struct S2 { int x; }
+return new S1.s=new S2;
 """);
         StopNode stop = parser.parse().iterate();
-        assertEquals("return ((flt)arg==(ToFloat+1.0));", stop.toString());
-        assertEquals(0L, Evaluator.evaluate(stop, 1));
+        assertEquals("return new S1;", stop.toString());
+    }
+
+    @Test
+    public void testcheckNull() {
+        Parser parser = new Parser(
+"""
+struct I {int i;}
+struct P {I pi;}
+P p1 = new P;
+P p2 = new P;
+p2.pi = new I;
+p2.pi.i = 2;
+if (arg) p1 = new P;
+return p1.pi.i + 1;
+""");
+        try { parser.parse().iterate();  fail(); }
+        catch( Exception e ) {  assertEquals("Might be null accessing 'i'",e.getMessage());  }
+    }
+
+
+    @Test
+    public void testShallowRecursiveType() {
+        new Parser("struct LLI { LLI? next; int i; } return 0;").parse().iterate();
+        TypeStruct l1 = (TypeStruct)Parser.TYPES.get("LLI");
+        TypeStruct l0 = ((TypeMemPtr)l1._fields[0]._type)._obj;
+        assertEquals("LLI", l0._name);
+        assertNull(l0._fields);
+        assertEquals(2, l1._fields.length);
+        assertSame(l0, l1.meet(l0));
+        assertSame(l0, l0.dual());
+        assertSame(l0, l0.glb());
+    }
+
+    @Test
+    public void testUnusedForwardReference() {
+        StopNode stop = new Parser("struct Holder { Missing? ref; } Holder h = new Holder; return h.ref;")
+            .parse().iterate();
+        assertEquals("return null;", stop.toString());
+        assertNull(((TypeStruct)Parser.TYPES.get("Missing"))._fields);
     }
 }
diff --git a/chapter14/src/test/java/com/seaofnodes/simple/Chapter13Test.java b/chapter14/src/test/java/com/seaofnodes/simple/Chapter13Test.java
index 15f97b79..34d71d9b 100644
--- a/chapter14/src/test/java/com/seaofnodes/simple/Chapter13Test.java
+++ b/chapter14/src/test/java/com/seaofnodes/simple/Chapter13Test.java
@@ -1,197 +1,532 @@
 package com.seaofnodes.simple;
 
+
 import com.seaofnodes.simple.evaluator.Evaluator;
 import com.seaofnodes.simple.node.StopNode;
-import org.junit.Ignore;
 import org.junit.Test;
+
+
 import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.fail;
 
 public class Chapter13Test {
+
+    // A placeholder test used to rapidly rotate through fuzzer produced issues
     @Test
-    public void testJig() {
+    public void testFuzzer() {
         Parser parser = new Parser(
 """
-return 3.14;
+while(-----arg) {
+    while(-arg) {
+        while(-----arg*---0) {
+                int N=--false==false<--arg;
+                while(N<-4==N) {
+                    N=N+N;
+                }
+            }
+        {
+            int kzEl_r7EYz=3*----0!=-arg<(37*--97!=0/arg==arg)<=-(--arg!=0);
+            while(kzEl_r7EYz<---1) {
+                kzEl_r7EYz=kzEl_r7EYz+kzEl_r7EYz*arg>=24;
+                if(7) continue;
+                kzEl_r7EYz=false;
+                if(-kzEl_r7EYz+arg<-3) continue;
+                else {
+                    while(kzEl_r7EYz) continue;
+                    arg=----3;
+                    kzEl_r7EYz=-(-----arg*1>-kzEl_r7EYz);
+                    int v2uF_4ba=9;
+                }
+            }
+        }
+        int pjcp7rv=arg;
+        {
+            int m2ya3=--arg-pjcp7rv;
+            while(m2ya3<-----pjcp7rv>=pjcp7rv+--pjcp7rv!=---pjcp7rv!=-arg<---(-m2ya3)>m2ya3<=-----true>14!=--m2ya3) {
+                m2ya3=m2ya3+-(--0<=false<pjcp7rv/arg<=-true);
+                while((--m2ya3)<--arg<-----arg*false!=arg<pjcp7rv*arg) {
+                    pjcp7rv=-3+-arg;
+                    break;
+                }
+                while(-3) {
+                    while(67+0-61) m2ya3=m2ya3;
+                    if(----pjcp7rv==---(---arg)) pjcp7rv=0!=-23;
+                    else pjcp7rv=----89;
+                    while(m2ya3!=m2ya3<pjcp7rv) m2ya3=1;
+                    while(--arg<=pjcp7rv) pjcp7rv=-32<=-m2ya3+62;
+                }
+                break;
+            }
+        }
+        {
+            int arg=-1<-9!=(-arg>=-pjcp7rv>=arg<=arg);
+            while(arg<-arg) {
+                arg=arg+--arg;
+                {
+                    while((--93)--pjcp7rv*-pjcp7rv+arg) arg=0-(6>=(--(---41/(0))!=--pjcp7rv)>=---2*33);
+                    pjcp7rv=11;
+                    int c=pjcp7rv;
+                    if(--107) break;
+                    else break;
+                }
+            }
+        }
+        pjcp7rv=pjcp7rv;
+        int aR0Wkua=-pjcp7rv==pjcp7rv;
+        {
+            if(-0!=-0) while(-true) break;
+            else {
+                while(aR0Wkua) pjcp7rv=-0/pjcp7rv;
+                pjcp7rv=pjcp7rv;
+            }
+        }
+    }
+    if(-arg) {
+        {
+            int Isdlt0fr91=0!=arg;
+            while(Isdlt0fr91<-Isdlt0fr91==-Isdlt0fr91+true) {
+                Isdlt0fr91=Isdlt0fr91+-1!=true;
+                if(-arg) if(--arg<=Isdlt0fr91) Isdlt0fr91=-Isdlt0fr91;
+                int i=---arg<---arg!=--40;
+                {
+                    int jVX43Ln4Dm=-(6)==-Isdlt0fr91/----0;
+                    while(jVX43Ln4Dm<--(3-3)) {
+                        jVX43Ln4Dm=jVX43Ln4Dm+-0<25;
+                        i=24<--(jVX43Ln4Dm);
+                    }
+                }
+                i=(arg!=----false>=7);
+                int Te=5>-arg;
+                break;
+            }
+        }
+        arg=arg!=--true/arg;
+        {
+            int UX=arg;
+            while(UX<-3*arg) {
+                UX=UX+arg/-1;
+                arg=-3--(-UX--47<arg==--arg==arg)/arg--UX>=-arg;
+                if(---12) while(-UX) break;
+                break;
+            }
+        }
+        continue;
+    }
+    if(arg) arg=--0;
+    else if(1) continue;
+    int DtTlhjYq=19==arg;
+    {
+        arg=--DtTlhjYq<=(DtTlhjYq/---DtTlhjYq<=-DtTlhjYq);
+        if(---arg) continue;
+        else {
+                int Zsl=40;
+                while(Zsl<--Zsl--false>((Zsl))==Zsl!=--DtTlhjYq-DtTlhjYq-DtTlhjYq) {
+                    Zsl=Zsl+arg;
+                }
+            }
+        if((arg)) if(-DtTlhjYq) {
+            }
+            else while(((2)==3*arg/DtTlhjYq)<=0==---arg) return false;
+        else {
+                int lwbF=arg>=0;
+                while(lwbF<57) {
+                    lwbF=lwbF+--(-arg+lwbF)>=-2>=arg!=arg;
+                    arg=----0+0;
+                    while(49) break;
+                    if(true) DtTlhjYq=-----arg;
+                    DtTlhjYq=0!=-----(0);
+                }
+            }
+        arg=---arg!=DtTlhjYq/--0;
+        DtTlhjYq=-DtTlhjYq/(--arg<arg);
+        if(32) {
+                int q=-DtTlhjYq;
+                while(q<arg*(0*q)/0) {
+                    q=q+DtTlhjYq;
+                    DtTlhjYq=arg;
+                }
+            }
+        else if(--arg) if(15) break;
+                else arg=0==arg<=-55>DtTlhjYq;
+            else {
+            }
+        DtTlhjYq=-0;
+        {
+            while((0)<-arg) DtTlhjYq=-DtTlhjYq;
+        }
+        if(30/--(arg)>=0) DtTlhjYq=-0>=arg;
+        else {
+            int Y2wcIQJ=--DtTlhjYq*---11;
+            if(arg==arg) {
+                Y2wcIQJ=-----Y2wcIQJ;
+                Y2wcIQJ=Y2wcIQJ<7;
+                if(DtTlhjYq) arg=arg;
+                else break;
+                while(-arg!=-31==(false<=-15>=-DtTlhjYq+--6*-----Y2wcIQJ<=---arg!=-Y2wcIQJ<=---0<-arg*--Y2wcIQJ)) DtTlhjYq=arg!=3;
+            }
+            continue;
+        }
+        arg=DtTlhjYq;
+        arg=--3/(---arg)>=80>=-DtTlhjYq<=DtTlhjYq;
+        arg=51+---(-true)!=arg!=----1==-DtTlhjYq;
+        if(11<=arg) if((arg)+79<32+(-arg)) continue;
+            else if(true==DtTlhjYq) break;
+        break;
+    }
+}
+if(arg!=62==arg) {
+    while(---arg) {
+        {
+            int bhmDacPM=arg/arg;
+            while(bhmDacPM<arg) {
+                bhmDacPM=bhmDacPM+80*((-bhmDacPM)/---bhmDacPM>1)<bhmDacPM-2!=7;
+                arg=-0;
+                arg=bhmDacPM>=-arg+-arg;
+                break;
+            }
+        }
+        int arg=true;
+        arg=arg<=arg;
+        {
+            int KlC=30;
+            while(KlC<-2) {
+                KlC=KlC+-1!=25<=-KlC>KlC>----0;
+                int Ij=arg>=-arg<=---10;
+                {
+                    int LAbgurVa2R=-arg!=Ij;
+                    while(LAbgurVa2R<-true) {
+                        LAbgurVa2R=LAbgurVa2R+Ij;
+                        KlC=-LAbgurVa2R;
+                        Ij=42*(-Ij>true);
+                        while(Ij) arg=KlC;
+                        KlC=-----7>-(--KlC<--7)==-LAbgurVa2R;
+                    }
+                }
+                int a=Ij<=-KlC;
+                if(Ij) {
+                    int r1W=a!=-false;
+                }
+                else {
+                    arg=56>=Ij;
+                    while(54) break;
+                    arg=8>=-(a<--Ij)/a>=-a-KlC;
+                }
+                int Yt_T=KlC;
+                arg=KlC;
+            }
+        }
+        if(----false/--arg/12+-----0) if(-9+-arg) while(arg!=(arg)) arg=--1>=-71-arg!=---(--arg*11+102)/--arg;
+            else if(----arg) continue;
+        if(-arg-arg) {
+            arg=-(-arg)*--(-3)<(-7==-arg----arg);
+            {
+                int arg=arg;
+                while(arg<-0>arg==-arg-(-arg>1+11)) {
+                    arg=arg+6-arg!=--0>---30>=---arg<=arg/(3)+---arg;
+                }
+            }
+            arg=-arg+arg;
+            arg=--47+-arg<1>arg*(-arg==-arg--0>3);
+            arg=(----arg)!=arg+--59;
+            arg=--4+arg==-(arg)-arg;
+        }
+        else {
+            while(--true-----true*-25+-18>arg>=-----(-arg)---13) {
+                arg=-0+--true<false;
+                continue;
+            }
+            arg=true<=arg;
+            break;
+        }
+        arg=arg*22<--(0+-arg);
+        {
+            continue;
+        }
+    }
+    arg=1*---((3<=true)==---2);
+    arg=7+-(-1);
+    return arg+--true;
+}
+else {
+    int o3ypEsewxM=-(---arg);
+    int vzXB=(-(---11<=--o3ypEsewxM>=--0))<=-0/-arg;
+    int L=-arg;
+    int B4mHcrf=---vzXB;
+    int oZWGdzZl=-o3ypEsewxM;
+    int K6tQqa1=11;
+    while(0!=--L) {
+            int sdZfTM=vzXB*true+K6tQqa1;
+            while(sdZfTM<false) {
+                sdZfTM=sdZfTM+arg;
+                sdZfTM=oZWGdzZl;
+                K6tQqa1=-K6tQqa1;
+                arg=---K6tQqa1;
+                while((3+-K6tQqa1)<oZWGdzZl) {
+                    if(-----(-1)) sdZfTM=-false;
+                    {}
+                }
+                K6tQqa1=vzXB!=-(B4mHcrf+-7>false);
+                sdZfTM=vzXB;
+            }
+        }
+    L=false;
+    while(31) B4mHcrf=arg;
+    oZWGdzZl=-0<--oZWGdzZl<=--2;
+    if(K6tQqa1>=20<=46) {
+        if(-1+-L) if(oZWGdzZl) {
+                int wmhv=-----0;
+            }
+        int arg=0;
+        o3ypEsewxM=---(oZWGdzZl);
+        return -oZWGdzZl/0;
+    }
+    else if(arg) {
+            int yKk5=B4mHcrf>=4>K6tQqa1<-B4mHcrf/o3ypEsewxM;
+            return -K6tQqa1;
+        }
+        else {
+            if(---0) {
+                {}
+                {}
+            }
+            return o3ypEsewxM;
+        }
+}
 """);
         StopNode stop = parser.parse().iterate();
-        assertEquals("return 3.14;", stop.toString());
-        assertEquals(3.14, Evaluator.evaluate(stop,  0));
+        assertEquals("Stop[ return 9; return 0; return 0; return 0; ]", stop.toString());
     }
 
+
     @Test
-    public void testLinkedList0() {
+    public void testPrimes() {
         Parser parser = new Parser(
 """
-struct LLI { LLI? next; int i; }
-LLI? head = null;
-while( arg ) {
-    LLI x = new LLI;
-    x.next = head;
-    x.i = arg;
-    head = x;
-    arg = arg-1;
+if( arg < 2 ) return 0;
+int primeCount = 1;
+int prime = 3;
+while( prime <= arg ) {
+    int isPrime = 1;
+    // Check for even case, so the next loop need only check odds
+    if( (prime/2)*2 == prime )
+        continue;
+    // Check odds up to sqrt of prime
+    int j = 3;
+    while( j*j <= prime ) {
+        if( (prime/j)*j == prime ) {
+            isPrime = 0;
+            break;
+        }
+        j = j + 2;
+    }
+    if( isPrime )
+        primeCount = primeCount + 1;
+    prime = prime + 2;
 }
-return head.next.i;
+return primeCount;
 """);
-        try { parser.parse().iterate(); fail(); }
-        catch( Exception e ) { assertEquals("Might be null accessing 'i'",e.getMessage()); }
+        StopNode stop = parser.parse().iterate();
+        assertEquals("Stop[ return 0; return Phi(Loop21,1,Phi(Region88,Phi_primeCount,Phi(Region82,(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
+        assertEquals(2L, Evaluator.evaluate(stop,  4)); // 2, 3
+        assertEquals(3L, Evaluator.evaluate(stop,  5)); // 2, 3, 5
+        assertEquals(4L, Evaluator.evaluate(stop, 10)); // 2, 3, 5, 7
     }
 
     @Test
-    public void testLinkedList1() {
+    public void testAntiDeps1() {
         Parser parser = new Parser(
 """
-struct LLI { LLI? next; int i; }
-LLI? head = null;
-while( arg ) {
-    LLI x = new LLI;
-    x.next = head;
-    x.i = arg;
-    head = x;
-    arg = arg-1;
-}
-if( !head ) return 0;
-LLI? next = head.next;
-if( next==null ) return 1;
-return next.i;
+struct S { int f; }
+S v=new S;
+v.f = 2;
+int i=new S.f;
+i=v.f;
+if (arg) v.f=1;
+return i;
 """);
         StopNode stop = parser.parse().iterate();
-        assertEquals("Stop[ return 0; return 1; return .i; ]", stop.toString());
-        assertEquals(2L, Evaluator.evaluate(stop,  3));
+        assertEquals("return .f;", stop.toString());
     }
 
     @Test
-    public void testCoRecur() {
+    public void testAntiDeps2() {
         Parser parser = new Parser(
 """
-struct int0 { int i; flt0? f; }
-struct flt0 { flt f; int0? i; }
-int0 i0 = new int0;
-i0.i = 17;
-flt0 f0 = new flt0;
-f0.f = 3.14;
-i0.f = f0;
-f0.i = i0;
-return f0.i.f.i.i;
+struct S { int f; }
+S v = new S;
+S t = new S;
+int i = 0;
+if (arg) {
+    if (arg+1) v = t;
+    i = v.f;
+} else {
+    v.f = 2;
+}
+return i;
 """);
         StopNode stop = parser.parse().iterate();
-        assertEquals("return 17;", stop.toString());
+        assertEquals("return Phi(Region37,.f,0);", stop.toString());
     }
 
     @Test
-    public void testNullRef0() {
+    public void testAntiDeps3() {
         Parser parser = new Parser(
 """
-struct N { N next; int i; }
-N n = new N;
-return n.next;
+struct S { int f; }
+S v0 = new S;
+S? v1;
+if (arg) v1 = new S;
+if (v1) {
+    v0.f = v1.f;
+} else {
+    v0.f = 2;
+}
+return v0;
 """);
         StopNode stop = parser.parse().iterate();
-        assertEquals("return null;", stop.toString());
+        assertEquals("return new S;", stop.toString());
     }
 
+
     @Test
-    public void testNullRef1() {
+    public void testAntiDeps4() {
         Parser parser = new Parser(
 """
-struct N { N next; int i; }
-N n = new N;
-n.next = new N;
-return n.next;
+struct S { int f; }
+S v = new S;
+S t = new S;
+int i = v.f;
+if (arg+1) arg= 0;
+while (arg) v.f = 2;
+return i;
 """);
         StopNode stop = parser.parse().iterate();
-        assertEquals("return new N;", stop.toString());
+        assertEquals("return .f;", stop.toString());
     }
 
     @Test
-    public void testNullRef2() {
+    public void testAntiDeps5() {
         Parser parser = new Parser(
 """
-struct N { N next; int i; }
-N n = new N;
-n.next = null;
-return n.next;
+struct S { int f; }
+S v = new S;
+while(1) {
+    while(arg+1) { arg=arg-1; }
+    if (arg) break;
+    v.f = 2;
+}
+return v;
 """);
-        try { parser.parse().iterate(); fail(); }
-        catch( Exception e ) { assertEquals("Cannot store null into field *N next",e.getMessage()); }
+        StopNode stop = parser.parse().iterate();
+        assertEquals("return new S;", stop.toString());
     }
 
     @Test
-    public void testNullRef3() {
+    public void testAntiDeps6() {
         Parser parser = new Parser(
 """
-struct N { N next; int i; }
-N n = new N;
-n.i = 3.14;
-return n.i;
+struct s { int v; }
+s ptr=new s;
+while( -arg )
+  ptr = new s;
+while(1)
+  arg = arg+ptr.v;
 """);
-        try { parser.parse().iterate(); fail(); }
-        catch( Exception e ) { assertEquals("Cannot store 3.14 into field int i",e.getMessage()); }
+        StopNode stop = parser.parse().iterate();
+        assertEquals("Stop[ return 0; return 0; ]", stop.toString());
     }
 
     @Test
-    public void testNullRef4() {
-        Parser parser = new Parser("-null-5/null-5");
-        try { parser.parse().iterate(); fail(); }
-        catch( Exception e ) { assertEquals("Expected an identifier, found 'null'",e.getMessage()); }
-    }
-
-    @Test public void testNullRef5() {
-        Parser parser = new Parser("return null+42;");
-        try { parser.parse().iterate(); fail(); }
-        catch( Exception e ) { assertEquals("Cannot 'Add' null",e.getMessage()); }
+    public void testAntiDeps7() {
+        Parser parser = new Parser(
+"""
+struct S { int f; }
+S v = new S;
+S t = new S;
+int i = v.f;
+while (arg) {
+    v.f = arg;
+    arg = arg-1;
+}
+return i;
+""");
+        StopNode stop = parser.parse().iterate();
+        assertEquals("return .f;", stop.toString());
     }
 
     @Test
-    public void testEmpty() {
+    public void testAntiDeps8() {
         Parser parser = new Parser(
 """
-struct S{};
+struct S { int f; }
+S v = new S;
+S t = new S;
+while(arg) {
+    arg=arg-1;
+    int f = v.f;
+    v.f = 2;
+    if (arg) arg = f;
+    else v.f = 3;
+}
+return arg;
 """);
         StopNode stop = parser.parse().iterate();
-        assertEquals("return 0;", stop.toString());
-        assertEquals(0L, Evaluator.evaluate(stop,  0));
+        assertEquals("return Phi(Loop17,arg,Phi(Region41,.f,0));", stop.toString());
     }
 
     @Test
-    public void testForwardRef0() {
+    public void testAntiDeps9() {
         Parser parser = new Parser(
 """
-struct S1 { S2 s; }
-return new S2;
+struct S { int f; }
+S v = new S;
+S t = new S;
+if (arg) {
+    v.f=2;
+    int i=t.f;
+    v.f=i;
+}
+return v;
 """);
-        try { parser.parse().iterate(); fail(); }
-        catch( Exception e ) { assertEquals("Unknown struct type 'S2'",e.getMessage()); }
+        StopNode stop = parser.parse().iterate();
+        assertEquals("return new S;", stop.toString());
     }
 
     @Test
-    public void testForwardRef1() {
+    public void testExample2() {
         Parser parser = new Parser(
-"""
-struct S1 { S2? s; }
-struct S2 { int x; }
-return new S1.s=new S2;
-""");
+                """
+struct S { int f; }
+S v = new S;
+int i = arg;
+while (arg > 0) {
+    int j = i/3;
+    if (arg == 5)
+        v.f = j;
+    arg = arg - 1;
+}
+return v;
+                """);
         StopNode stop = parser.parse().iterate();
-        assertEquals("return new S1;", stop.toString());
+        //assertEquals("return new S;", stop.toString());
     }
 
     @Test
-    public void testcheckNull() {
+    public void testSplit() {
         Parser parser = new Parser(
-"""
-struct I {int i;}
-struct P {I pi;}
-P p1 = new P;
-P p2 = new P;
-p2.pi = new I;
-p2.pi.i = 2;
-if (arg) p1 = new P;
-return p1.pi.i + 1;
+                                   """
+struct S { int f; }
+S s = new S;
+if( arg==0 ) s.f = 1;
+else if (arg == 1) s.f = 1;
+return s.f;
 """);
-        try { parser.parse().iterate();  fail(); }
-        catch( Exception e ) {  assertEquals("Might be null accessing 'i'",e.getMessage());  }
+        StopNode stop = parser.parse().iterate();
+        assertEquals("return Phi(Region43,1,Phi(Region38,1,0));", stop.toString());
+        assertEquals(1L, Evaluator.evaluate(stop,  0));
+        assertEquals(1L, Evaluator.evaluate(stop,  1));
+        assertEquals(0L, Evaluator.evaluate(stop,  2));
     }
-
 }
diff --git a/chapter14/src/test/java/com/seaofnodes/simple/Chapter14FloatTest.java b/chapter14/src/test/java/com/seaofnodes/simple/Chapter14FloatTest.java
new file mode 100644
index 00000000..f2b51da2
--- /dev/null
+++ b/chapter14/src/test/java/com/seaofnodes/simple/Chapter14FloatTest.java
@@ -0,0 +1,95 @@
+package com.seaofnodes.simple;
+
+import com.seaofnodes.simple.evaluator.Evaluator;
+import com.seaofnodes.simple.node.StopNode;
+import org.junit.Ignore;
+import org.junit.Test;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.fail;
+
+public class Chapter14FloatTest {
+    @Test public void testSubZeroFloat() {
+        var stop = new Parser("flt x = arg; return 0-x;").parse().iterate();
+        // Compare strings so +0.0 and -0.0 remain distinct.
+        assertEquals("0.0", Evaluator.evaluate(stop,0).toString());
+        assertEquals("-1.0", Evaluator.evaluate(stop,1).toString());
+    }
+
+    @Test public void testDeadNumericReturns() {
+        for( String[] test : new String[][] {
+            {"if(1) return 7; else return 2.5;", "7"},
+            {"if(0) return 7; else return 2.5;", "2.5"},
+            {"return 7; return 2.5;", "7"},
+            {"return 2.5; return 7;", "2.5"}
+        } ) {
+            String src = test[0];
+            var stop = new Parser(src).parse().iterate();
+            assertEquals(src,test[1],com.seaofnodes.simple.evaluator.Evaluator.evaluate(stop,0).toString());
+        }
+    }
+
+
+    @Test
+    public void testJig() {
+        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 testFloat() {
+        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 testSquareRoot() {
+        Parser parser = new Parser(
+"""
+flt guess = arg;
+while( 1 ) {
+    flt next = (arg/guess + guess)/2;
+    if( next == guess ) break;
+    guess = next;
+}
+return guess;
+""");
+        StopNode stop = parser.parse().iterate();
+        assertEquals("return Phi(Loop10,(flt)arg,(((ToFloat/Phi_guess)+Phi_guess)/2.0));", stop.toString());
+        assertEquals(3.0, Evaluator.evaluate(stop,  9));
+        assertEquals(1.414213562373095, Evaluator.evaluate(stop,  2));
+    }
+
+    @Test
+    public void testFPOps() {
+        Parser parser = new Parser(
+"""
+flt x = arg;
+return x+1==x;
+""");
+        StopNode stop = parser.parse().iterate();
+        assertEquals("return ((flt)arg==(ToFloat+1.0));", stop.toString());
+        assertEquals(0L, Evaluator.evaluate(stop, 1));
+    }
+    @Test
+    public void testReferenceFieldRejectsFloat() {
+        Parser parser = new Parser(
+"""
+struct N { N next; int i; }
+N n = new N;
+n.i = 3.14;
+return n.i;
+""");
+        try { parser.parse().iterate(); fail(); }
+        catch( Exception e ) { assertEquals("Cannot store 3.14 into field int i",e.getMessage()); }
+    }
+}