Chapter 18: Functions

Co-authored-by: tannal <tannal2409@gmail.com>
Co-authored-by: hadha <helsgithub15@gmail.com>
Co-authored-by: Tamás Hadházy <85063808+Hels15@users.noreply.github.com>

29 files changed, 1998 insertions, 1054 deletions

diff --git a/src/test/java/com/seaofnodes/simple/BrainFuckTest.java b/src/test/java/com/seaofnodes/simple/BrainFuckTest.java
index 88d79215..37ecde1c 100644
--- a/src/test/java/com/seaofnodes/simple/BrainFuckTest.java
+++ b/src/test/java/com/seaofnodes/simple/BrainFuckTest.java
@@ -1,12 +1,8 @@
 package com.seaofnodes.simple;
 
 import com.seaofnodes.simple.evaluator.Evaluator;
-import com.seaofnodes.simple.node.StopNode;
-import org.junit.Test;
-import org.junit.Ignore;
-
 import java.nio.charset.StandardCharsets;
-
+import org.junit.Test;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.fail;
 
@@ -21,9 +17,10 @@ public class BrainFuckTest {
             encoded.append("program[").append(i).append("] = ").append(value).append(";");
         }
 
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
                 encoded + """
-var d = 0;
+
+int d = 0;
 u8[] !output = new u8[0];
 u8[] !data = new u8[100];
 
@@ -41,14 +38,14 @@ for( int pc = 0; pc < program#; pc++ ) {
         // Output a byte; increase the output array size
         var old = output;
         output = new u8[output# + 1];
-        for( var i = 0; i < old#; i++ )
+        for( int i = 0; i < old#; i++ )
             output[i] = old[i];
         output[old#] = data[d]; // Add the extra byte on the end
     } else if (command == 44) {
         data[d] = 42;
     } else if (command == 91) {
         if (data[d] == 0) {
-            for( var d = 1; d > 0; ) {
+            for( int d = 1; d > 0; ) {
                 command = program[++pc];
                 if (command == 91) d++;
                 if (command == 93) d--;
@@ -56,7 +53,7 @@ for( int pc = 0; pc < program#; pc++ ) {
         }
     } else if (command == 93) {
         if (data[d]) {
-            for( var d = 1; d > 0; ) {
+            for( int d = 1; d > 0; ) {
                 command = program[--pc];
                 if (command == 93) d++;
                 if (command == 91) d--;
@@ -66,7 +63,7 @@ for( int pc = 0; pc < program#; pc++ ) {
 }
 return output;
                 """);
-        StopNode stop = parser.parse(false).iterate(false);
-        assertEquals("Hello World!\n", Evaluator.evaluate(stop, 0, 10000).toString());
+        code.parse().opto().typeCheck().GCM();
+        assertEquals("Hello World!\n", Eval2.eval(code, 0, 10000));
     }
 }
diff --git a/src/test/java/com/seaofnodes/simple/Chapter01Test.java b/src/test/java/com/seaofnodes/simple/Chapter01Test.java
index f7524c17..934eda76 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter01Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter01Test.java
@@ -10,15 +10,10 @@ public class Chapter01Test {
 
     @Test
     public void testSimpleProgram() {
-        Parser parser = new Parser("return 1;");
-        StopNode stop = parser.parse();
-        StartNode start = Parser.START;
-        ReturnNode ret = (ReturnNode)stop.in(0);
-
-        assertTrue(ret.ctrl() instanceof CProjNode);
-        Node expr = ret.expr();
+        CodeGen code = new CodeGen("return 1;").parse();
+        Node expr = code.expr();
         if( expr instanceof ConstantNode con ) {
-            assertEquals(start,con.in(0));
+            assertEquals(code._start,con.in(0));
             assertEquals(TypeInteger.constant(1), con._type);
         } else {
             fail();
@@ -27,10 +22,9 @@ public class Chapter01Test {
 
     @Test
     public void testZero() {
-        Parser parser = new Parser("return 0;");
-        parser.parse();
-        StartNode start = Parser.START;
-        for( Node use : start._outputs )
+        CodeGen code = new CodeGen("return 0;");
+        code.parse();
+        for( Node use : code._start._outputs )
             if( use instanceof ConstantNode con && con._type instanceof TypeInteger )
                 assertEquals(TypeInteger.constant(0),con._type);
     }
@@ -38,7 +32,7 @@ public class Chapter01Test {
     @Test
     public void testBad1() {
         try {
-            new Parser("ret").parse();
+            new CodeGen("ret;").parse();
             fail();
         } catch( RuntimeException e ) {
             assertEquals("Undefined name 'ret'",e.getMessage());
@@ -48,7 +42,7 @@ public class Chapter01Test {
     @Test
     public void testBad2() {
         try {
-            new Parser("return 0123;").parse();
+            new CodeGen("return 0123;").parse();
             fail();
         } catch( RuntimeException e ) {
             assertEquals("Syntax error: integer values cannot start with '0'",e.getMessage());
@@ -58,13 +52,13 @@ public class Chapter01Test {
     @Test
     public void testNotBad3() {
         // this test used to fail in chapter 1
-        assertEquals("return 12;", new Parser("return - -12;").parse().print());
+        assertEquals("return 12;", new CodeGen("return - -12;").parse()._stop.print());
     }
 
     @Test
     public void testBad4() {
         try {
-            new Parser("return 100").parse();
+            new CodeGen("return 100").parse();
             fail();
         } catch( RuntimeException e ) {
             assertEquals("Syntax error, expected ;: ",e.getMessage());
@@ -74,13 +68,13 @@ public class Chapter01Test {
     @Test
     public void testNotBad5() {
         // this test used to fail in chapter 1
-        assertEquals("return -100;", new Parser("return -100;").parse().print());
+        assertEquals("return -100;", new CodeGen("return -100;").parse()._stop.print());
     }
 
     @Test
     public void testBad6() {
         try {
-            new Parser("return100").parse();
+            new CodeGen("return100;").parse();
             fail();
         } catch( RuntimeException e ) {
             assertEquals("Undefined name 'return100'",e.getMessage());
@@ -90,10 +84,10 @@ public class Chapter01Test {
     @Test
     public void testBad7() {
         try {
-            new Parser("return 1;}").parse();
+            new CodeGen("return 1;}").parse();
             fail();
         } catch( RuntimeException e ) {
-            assertEquals("Syntax error, unexpected }",e.getMessage());
+            assertEquals("Syntax error, unexpected: }",e.getMessage());
         }
     }
 
diff --git a/src/test/java/com/seaofnodes/simple/Chapter02Test.java b/src/test/java/com/seaofnodes/simple/Chapter02Test.java
index 75ee0b70..324ebf41 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter02Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter02Test.java
@@ -10,53 +10,51 @@ public class Chapter02Test {
 
     @Test
     public void testParseGrammar() {
-        Parser parser = new Parser("return 1+2*3+-5;");
-        Node._disablePeephole = true; // disable peephole so we can observe full graph
-        StopNode ret = parser.parse();
-        assertEquals("return ((1+(2*3))+(-5));", ret.print());
-        Node._disablePeephole = false;
+        CodeGen code = new CodeGen("return 1+2*3+-5;");
+        code.parse(true); // Disable peepholes
+        assertEquals("return ((1+(2*3))+(-5));", code.print());
     }
 
     @Test
     public void testAddPeephole() {
-        Parser parser = new Parser("return 1+2;");
-        StopNode ret = parser.parse();
-        assertEquals("return 3;", ret.print());
+        CodeGen code = new CodeGen("return 1+2;");
+        code.parse();
+        assertEquals("return 3;", code.print());
     }
 
     @Test
     public void testSubPeephole() {
-        Parser parser = new Parser("return 1-2;");
-        StopNode ret = parser.parse();
-        assertEquals("return -1;", ret.print());
+        CodeGen code = new CodeGen("return 1-2;");
+        code.parse();
+        assertEquals("return -1;", code.print());
     }
 
     @Test
     public void testMulPeephole() {
-        Parser parser = new Parser("return 2*3;");
-        StopNode ret = parser.parse();
-        assertEquals("return 6;", ret.print());
+        CodeGen code = new CodeGen("return 2*3;");
+        code.parse();
+        assertEquals("return 6;", code.print());
     }
 
     @Test
     public void testDivPeephole() {
-        Parser parser = new Parser("return 6/3;");
-        StopNode ret = parser.parse();
-        assertEquals("return 2;", ret.print());
+        CodeGen code = new CodeGen("return 6/3;");
+        code.parse();
+        assertEquals("return 2;", code.print());
     }
 
     @Test
     public void testMinusPeephole() {
-        Parser parser = new Parser("return 6/-3;");
-        StopNode ret = parser.parse();
-        assertEquals("return -2;", ret.print());
+        CodeGen code = new CodeGen("return 6/-3;");
+        code.parse();
+        assertEquals("return -2;", code.print());
     }
 
     @Test
     public void testExample() {
-        Parser parser = new Parser("return 1+2*3+-5;");
-        StopNode ret = parser.parse();
-        assertEquals("return 2;", ret.print());
+        CodeGen code = new CodeGen("return 1+2*3+-5;");
+        code.parse();
+        assertEquals("return 2;", code.print());
     }
 
 }
diff --git a/src/test/java/com/seaofnodes/simple/Chapter03Test.java b/src/test/java/com/seaofnodes/simple/Chapter03Test.java
index 2de0b46e..825235cc 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter03Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter03Test.java
@@ -1,7 +1,5 @@
 package com.seaofnodes.simple;
 
-import com.seaofnodes.simple.node.*;
-import com.seaofnodes.simple.type.TypeInteger;
 import org.junit.Test;
 
 import static org.junit.Assert.*;
@@ -10,45 +8,42 @@ public class Chapter03Test {
 
     @Test
     public void testVarDecl() {
-        Parser parser = new Parser("int a=1; return a;");
-        StopNode ret = parser.parse();
-        assertEquals("return 1;", ret.print());
+        CodeGen code = new CodeGen("int a=1; return a;");
+        code.parse(); assertEquals("return 1;", code.print());
     }
 
     @Test
     public void testVarAdd() {
-        Parser parser = new Parser("int a=1; int b=2; return a+b;");
-        StopNode ret = parser.parse();
-        assertEquals("return 3;", ret.print());
+        CodeGen code = new CodeGen("int a=1; int b=2; return a+b;");
+        code.parse();
+        assertEquals("return 3;", code.print());
     }
 
     @Test
     public void testVarScope() {
-        Parser parser = new Parser("int a=1; int b=2; int c=0; { int b=3; c=a+b; } return c;");
-        StopNode ret = parser.parse();
-        assertEquals("return 4;", ret.print());
+        CodeGen code = new CodeGen("int a=1; int b=2; int c=0; { int b=3; c=a+b; } return c;");
+        code.parse();
+        assertEquals("return 4;", code.print());
     }
 
     @Test
     public void testVarScopeNoPeephole() {
-        Parser parser = new Parser("int a=1; int b=2; int !c=0; { int b=3; c=a+b;  } return c; ");
-        Node._disablePeephole = true;
-        StopNode ret = parser.parse();
-        Node._disablePeephole = false;
-        assertEquals("return (1+3);", ret.print());
+        CodeGen code = new CodeGen("int a=1; int b=2; int !c=0; { int b=3; c=a+b;  } return c; ");
+        code.parse(true);
+        assertEquals("return (1+3);", code.print());
     }
 
     @Test
     public void testVarDist() {
-        Parser parser = new Parser("int x0=1; int y0=2; int x1=3; int y1=4; return (x0-x1)*(x0-x1) + (y0-y1)*(y0-y1); ");
-        StopNode ret = parser.parse();
-        assertEquals("return 8;", ret.print());
+        CodeGen code = new CodeGen("int x0=1; int y0=2; int x1=3; int y1=4; return (x0-x1)*(x0-x1) + (y0-y1)*(y0-y1); ");
+        code.parse();
+        assertEquals("return 8;", code.print());
     }
 
     @Test
     public void testSelfAssign() {
         try {
-            new Parser("int a=a; return a;").parse();
+            new CodeGen("int a=a; return a;").parse();
             fail();
         } catch( RuntimeException e ) {
             assertEquals("Undefined name 'a'",e.getMessage());
@@ -68,7 +63,7 @@ public class Chapter03Test {
     @Test
     public void testBad1() {
         try {
-            new Parser("int a=1; int b=2; int !c=0; { int b=3; c=a+b;").parse();
+            new CodeGen("int a=1; int b=2; int !c=0; { int b=3; c=a+b;").parse();
             fail();
         } catch( RuntimeException e ) {
             assertEquals("Syntax error, expected }: ",e.getMessage());
diff --git a/src/test/java/com/seaofnodes/simple/Chapter04Test.java b/src/test/java/com/seaofnodes/simple/Chapter04Test.java
index 0db3afde..afed67d1 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter04Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter04Test.java
@@ -3,6 +3,7 @@ package com.seaofnodes.simple;
 import com.seaofnodes.simple.node.*;
 import com.seaofnodes.simple.type.TypeInteger;
 import org.junit.Test;
+import org.junit.Ignore;
 
 import static org.junit.Assert.*;
 
@@ -10,102 +11,102 @@ public class Chapter04Test {
 
     @Test
     public void testPeephole() {
-        Parser parser = new Parser("return 1+arg+2; ");
-        StopNode ret = parser.parse();
-        assertEquals("return (arg+3);", ret.print());
+        CodeGen code = new CodeGen("return 1+arg+2; ");
+        code.parse();
+        assertEquals("return (arg+3);", code.print());
     }
 
     @Test
     public void testPeephole2() {
-        Parser parser = new Parser("return (1+arg)+2;");
-        StopNode ret = parser.parse();
-        assertEquals("return (arg+3);", ret.print());
+        CodeGen code = new CodeGen("return (1+arg)+2;");
+        code.parse();
+        assertEquals("return (arg+3);", code.print());
     }
 
     @Test
     public void testAdd0() {
-        Parser parser = new Parser("return 0+arg;");
-        StopNode ret = parser.parse();
-        assertEquals("return arg;", ret.print());
+        CodeGen code = new CodeGen("return 0+arg;");
+        code.parse();
+        assertEquals("return arg;", code.print());
     }
 
     @Test
     public void testAddAddMul() {
-        Parser parser = new Parser("return arg+0+arg;");
-        StopNode ret = parser.parse();
-        assertEquals("return (arg*2);", ret.print());
+        CodeGen code = new CodeGen("return arg+0+arg;");
+        code.parse();
+        assertEquals("return (arg*2);", code.print());
     }
 
     @Test
     public void testPeephole3() {
-        Parser parser = new Parser("return 1+arg+2+arg+3; ");
-        StopNode ret = parser.parse();
-        assertEquals("return ((arg*2)+6);", ret.print());
+        CodeGen code = new CodeGen("return 1+arg+2+arg+3; ");
+        code.parse();
+        assertEquals("return ((arg*2)+6);", code.print());
     }
 
     @Test
     public void testMul1() {
-        Parser parser = new Parser("return 1*arg;");
-        StopNode ret = parser.parse();
-        assertEquals("return arg;", ret.print());
+        CodeGen code = new CodeGen("return 1*arg;");
+        code.parse();
+        assertEquals("return arg;", code.print());
     }
 
     @Test
     public void testVarArg() {
-        Parser parser = new Parser("return arg; ");
-        StopNode stop = parser.parse();
-        ReturnNode ret = stop.ret();
-        assertTrue(ret.in(0) instanceof CProjNode);
-        assertTrue(ret.in(1) instanceof  ProjNode);
+        CodeGen code = new CodeGen("return arg; ");
+        code.parse();
+        assertTrue(code.ctrl() instanceof  FunNode);
+        assertTrue(code.expr() instanceof ParmNode);
     }
 
-    @Test
+    // Adding functions means `main` does not constant fold the incoming arg value
+    @Ignore @Test
     public void testConstantArg() {
-        Parser parser = new Parser("return arg; ", TypeInteger.constant(2));
-        StopNode ret = parser.parse();
-        assertEquals("return 2;", ret.print());
+        CodeGen code = new CodeGen("return arg; ", TypeInteger.constant(2));
+        code.parse();
+        assertEquals("return 2;", code.expr().in(1).toString());
     }
 
     @Test
     public void testCompEq() {
-        Parser parser = new Parser("return 3==3; ");
-        StopNode ret = parser.parse();
-        assertEquals("return 1;", ret.print());
+        CodeGen code = new CodeGen("return 3==3; ");
+        code.parse();
+        assertEquals("return 1;", code.print());
     }
 
     @Test
     public void testCompEq2() {
-        Parser parser = new Parser("return 3==4; ");
-        StopNode ret = parser.parse();
-        assertEquals("return 0;", ret.print());
+        CodeGen code = new CodeGen("return 3==4; ");
+        code.parse();
+        assertEquals("return 0;", code.print());
     }
 
     @Test
     public void testCompNEq() {
-        Parser parser = new Parser("return 3!=3; ");
-        StopNode ret = parser.parse();
-        assertEquals("return 0;", ret.print());
+        CodeGen code = new CodeGen("return 3!=3; ");
+        code.parse();
+        assertEquals("return 0;", code.print());
     }
 
     @Test
     public void testCompNEq2() {
-        Parser parser = new Parser("return 3!=4; ");
-        StopNode ret = parser.parse();
-        assertEquals("return 1;", ret.print());
+        CodeGen code = new CodeGen("return 3!=4; ");
+        code.parse();
+        assertEquals("return 1;", code.print());
     }
 
     @Test
     public void testBug1() {
-        Parser parser = new Parser("int a=arg+1; int !b=a; b=1; return a+2; ");
-        StopNode ret = parser.parse();
-        assertEquals("return (arg+3);", ret.print());
+        CodeGen code = new CodeGen("int a=arg+1; int !b=a; b=1; return a+2; ");
+        code.parse();
+        assertEquals("return (arg+3);", code.print());
     }
 
     @Test
     public void testBug2() {
-        Parser parser = new Parser("int !a=arg+1; a=a; return a; ");
-        StopNode ret = parser.parse();
-        assertEquals("return (arg+1);", ret.print());
+        CodeGen code = new CodeGen("int !a=arg+1; a=a; return a; ");
+        code.parse();
+        assertEquals("return (arg+1);", code.print());
     }
 
     @Test
@@ -120,9 +121,9 @@ public class Chapter04Test {
 
     @Test
     public void testBug4() {
-        Parser parser = new Parser("return -arg;");
-        StopNode ret = parser.parse();
-        assertEquals("return (-arg);", ret.print());
+        CodeGen code = new CodeGen("return -arg;");
+        code.parse();
+        assertEquals("return (-arg);", code.print());
     }
 
     @Test
diff --git a/src/test/java/com/seaofnodes/simple/Chapter05Test.java b/src/test/java/com/seaofnodes/simple/Chapter05Test.java
index 9afb8f28..f4db5624 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter05Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter05Test.java
@@ -1,7 +1,6 @@
 package com.seaofnodes.simple;
 
 import com.seaofnodes.simple.node.*;
-import com.seaofnodes.simple.type.TypeInteger;
 import org.junit.Test;
 
 import static org.junit.Assert.*;
@@ -10,7 +9,7 @@ public class Chapter05Test {
 
     @Test
     public void testIfStmt() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 int a = 1;
 if (arg == 1)
@@ -20,13 +19,13 @@ else {
 }
 return a;
 """);
-        StopNode ret = parser.parse().iterate();
-        assertEquals("return Phi(Region,(arg+2),(arg-3));", ret.toString());
+        code.parse().opto();
+        assertEquals("return Phi(Region,(arg+2),(arg-3));", code.print());
     }
 
     @Test
     public void testTest() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 int c = 3;
 int b = 2;
@@ -34,27 +33,28 @@ if (arg == 1) {
     b = 3;
     c = 4;
 }
-return c;""", TypeInteger.BOT);
-        StopNode ret = parser.parse().iterate();
-        assertEquals("return Phi(Region,4,3);", ret.toString());
+return c;
+""");
+        code.parse().opto();
+        assertEquals("return Phi(Region,4,3);", code.print());
     }
 
     @Test
     public void testReturn2() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 if( arg==1 )
     return 3;
 else
     return 4;
-""", TypeInteger.BOT);
-        StopNode stop = parser.parse();
-        assertEquals("Stop[ return 3; return 4; ]", stop.toString());
+""");
+        code.parse();
+        assertEquals("return Phi(Region,3,4);", code.print());
     }
 
     @Test
     public void testIfMergeB() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 int a=arg+1;
 int b=0;
@@ -63,13 +63,13 @@ if( arg==1 )
 else
     b=a+1;
 return a+b;""");
-        StopNode ret = parser.parse().iterate();
-        assertEquals("return ((arg*2)+Phi(Region,2,3));", ret.toString());
+        code.parse().opto();
+        assertEquals("return ((arg*2)+Phi(Region,2,3));", code.print());
     }
 
     @Test
     public void testIfMerge2() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 int a=arg+1;
 int b=arg+2;
@@ -78,13 +78,13 @@ if( arg==1 )
 else
     a=b+1;
 return a+b;""");
-        StopNode ret = parser.parse().iterate();
-        assertEquals("return ((Phi(Region,(arg*2),arg)+arg)+Phi(Region,4,5));", ret.toString());
+        code.parse().opto();
+        assertEquals("return ((Phi(Region,(arg*2),arg)+arg)+Phi(Region,4,5));", code.print());
     }
 
     @Test
     public void testMerge3() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 int a=1;
 if( arg==1 )
@@ -97,14 +97,14 @@ else if( arg==3 )
 else
     a=5;
 return a;
-""", TypeInteger.BOT);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Region,Phi(Region,2,3),Phi(Region,4,5));", stop.toString());
+""");
+        code.parse().opto();
+        assertEquals("return Phi(Region,Phi(Region,2,3),Phi(Region,4,5));", code.print());
     }
 
     @Test
     public void testMerge4() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 int a=0;
 int b=0;
@@ -113,38 +113,39 @@ if( arg )
 if( arg==0 )
     b=2;
 return arg+a+b;
-""", TypeInteger.BOT);
-        StopNode stop = parser.parse();
-        assertEquals("return ((arg+Phi(Region,1,0))+Phi(Region,2,0));", stop.toString());
+""");
+        code.parse().opto();
+        assertEquals("return ((arg+Phi(Region,1,0))+Phi(Region,2,0));", code.print());
     }
 
     @Test
     public void testMerge5() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 int a=arg==2;
 if( arg==1 )
 {
     a=arg==3;
 }
-return a;""");
-        StopNode ret = parser.parse().iterate();
-        assertEquals("return (arg==Phi(Region,3,2));", ret.toString());
+return a;
+""");
+        code.parse().opto();
+        assertEquals("return (arg==Phi(Region,3,2));", code.print());
     }
 
     @Test
     public void testTrue() {
       StopNode stop = new Parser("return true;").parse();
-      assertEquals("return 1;",stop.toString());
+      assertEquals("return 1;",stop.ret().print());
     }
 
     @Test
     public void testHalfDef() {
         try {
-            new Parser("if( arg==1 ) int b=2; return b;").parse();
+            new CodeGen("if( arg==1 ) int b=2; return b;").parse();
             fail();
         } catch( RuntimeException e ) {
-            assertEquals("Cannot define a new name on one arm of an if",e.getMessage());
+            assertEquals("Cannot define a 'b' on one arm of an if",e.getMessage());
         }
     }
 
@@ -161,10 +162,10 @@ return a;""");
     @Test
     public void testRegress1() {
         try {
-            new Parser("if(arg==2) int a=1; else int b=2; return a;").parse();
+            new CodeGen("if(arg==2) int a=1; else int b=2; return a;").parse();
             fail();
         } catch( RuntimeException e ) {
-            assertEquals("Cannot define a new name on one arm of an if",e.getMessage());
+            assertEquals("Cannot define a 'a' on one arm of an if",e.getMessage());
         }
     }
 
@@ -202,7 +203,7 @@ return a;""");
     @Test
     public void testKeyword3() {
         try {
-            new Parser("int a=1; ififif(arg)inta=2;return a;").parse();
+            new CodeGen("int a=1; ififif(arg);a=2;return a;").parse();
             fail();
         } catch( RuntimeException e ) {
             assertEquals("Undefined name 'ififif'",e.getMessage());
diff --git a/src/test/java/com/seaofnodes/simple/Chapter06Test.java b/src/test/java/com/seaofnodes/simple/Chapter06Test.java
index 50c0580d..2107cdb0 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter06Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter06Test.java
@@ -10,32 +10,31 @@ public class Chapter06Test {
 
     @Test
     public void testPeepholeReturn() {
-        Parser parser = new Parser(
-"""
+        CodeGen code = new CodeGen("""
 if( true ) return 2;
 return 1;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 2;", stop.toString());
-        assertTrue(stop.ret().ctrl() instanceof CProjNode);
+        code.parse().opto();
+        assertEquals("return 2;", code.print());
+        assertTrue(code.ctrl() instanceof FunNode);
     }
 
     @Test
     public void testPeepholeRotate() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 int a = 1;
 if (arg)
     a = 2;
 return (arg < a) < 3; // Because (arg < a) is a bool/uint1/[0-1], its always less than 3
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 1;", stop.toString());
+        code.parse().opto();
+        assertEquals("return 1;", code.print());
     }
 
     @Test
     public void testPeepholeCFG() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 int a=1;
 if( true )
@@ -44,14 +43,14 @@ else
   a=3;
 return a;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 2;", stop.toString());
-        assertTrue(stop.ret().ctrl() instanceof CProjNode);
+        code.parse().opto();
+        assertEquals("return 2;", code.print());
+        assertTrue(code.ctrl() instanceof FunNode);
     }
 
     @Test
     public void testIfIf() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 int a=1;
 if( arg!=1 )
@@ -63,14 +62,15 @@ if( a==2 )
     b=42;
 else
     b=5;
-return b;""", TypeInteger.BOT);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Region,42,5);", stop.toString());
+return b;
+""");
+        code.parse().opto();
+        assertEquals("return Phi(Region,42,5);", code.print());
     }
 
     @Test
     public void testIfArgIf() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 int a=1;
 if( 1==1 )
@@ -82,15 +82,16 @@ if( arg==2 )
     b=a;
 else
     b=5;
-return b;""", TypeInteger.BOT);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Region,2,5);", stop.toString());
+return b;""");
+        code.parse().opto();
+        assertEquals("return Phi(Region,2,5);", code.print());
     }
 
     @Test
     public void testMerge3With2() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
+arg=2;
 int a=1;
 if( arg==1 )
     if( arg==2 )
@@ -103,14 +104,15 @@ else
     a=5;
 return a;
 """, TypeInteger.constant(2));
-        StopNode stop = parser.parse();
-        assertEquals("return 5;", stop.toString());
+        code.parse().opto();
+        assertEquals("return 5;", code.print());
     }
 
     @Test
     public void testMerge3With1() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
+arg=1;
 int a=1;
 if( arg==1 )
     if( arg==2 )
@@ -123,13 +125,13 @@ else
     a=5;
 return a;
 """, TypeInteger.constant(1));
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 3;", stop.toString());
+        code.parse().opto();
+        assertEquals("return 3;", code.print());
     }
 
     @Test
     public void testMerge3Peephole() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 int a=1;
 if( arg==1 )
@@ -142,15 +144,16 @@ else if( arg==3 )
 else
     a=5;
 return a;
-""", TypeInteger.BOT);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Region,3,Phi(Region,4,5));", stop.toString());
+""");
+        code.parse().opto();
+        assertEquals("return Phi(Region,3,Phi(Region,4,5));", code.print());
     }
 
     @Test
     public void testMerge3Peephole1() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
+arg=1;
 int a=1;
 if( arg==1 )
     if( 1==2 )
@@ -163,14 +166,15 @@ else
     a=5;
 return a;
 """, TypeInteger.constant(1));
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 3;", stop.toString());
+        code.parse().opto();
+        assertEquals("return 3;", code.print());
     }
 
     @Test
     public void testMerge3Peephole3() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
+arg=3;
 int a=1;
 if( arg==1 )
     if( 1==2 )
@@ -183,13 +187,13 @@ else
     a=5;
 return a;
 """, TypeInteger.constant(3));
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 4;", stop.toString());
+        code.parse().opto();
+        assertEquals("return 4;", code.print());
     }
 
     @Test
     public void testDemo1NonConst() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 int a = 0;
 int b = 1;
 if( arg ) {
@@ -199,14 +203,15 @@ if( arg ) {
 }
 return a+b;
 """);
-        StopNode ret = parser.parse().iterate();
-        assertEquals("return Phi(Region,4,1);", ret.toString());
+        code.parse().opto();
+        assertEquals("return Phi(Region,4,1);", code.print());
     }
 
 
     @Test
     public void testDemo1True() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
+arg=1;
 int a = 0;
 int b = 1;
 if( arg ) {
@@ -216,13 +221,14 @@ if( arg ) {
 }
 return a+b;
 """, TypeInteger.constant(1));
-        StopNode ret = parser.parse().iterate();
-        assertEquals("return 4;", ret.toString());
+        code.parse().opto();
+        assertEquals("return 4;", code.print());
     }
 
     @Test
     public void testDemo1False() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
+arg=0;
 int a = 0;
 int b = 1;
 if( arg ) {
@@ -232,13 +238,13 @@ if( arg ) {
 }
 return a+b;
 """, TypeInteger.constant(0));
-        StopNode ret = parser.parse().iterate();
-        assertEquals("return 1;", ret.toString());
+        code.parse().opto();
+        assertEquals("return 1;", code.print());
     }
 
     @Test
     public void testDemo2NonConst() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 int a = 0;
 int b = 1;
 int c = 0;
@@ -250,14 +256,15 @@ if( arg ) {
 }
 return a+b+c;
 """);
-        StopNode ret = parser.parse().iterate();
-        assertEquals("return (Phi(Region,Phi(Region,2,3),0)+Phi(Region,3,1));", ret.toString());
+        code.parse().opto();
+        assertEquals("return (Phi(Region,Phi(Region,2,3),0)+Phi(Region,3,1));", code.print());
     }
 
 
     @Test
     public void testDemo2True() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
+arg=1;
 int a = 0;
 int b = 1;
 int c = 0;
@@ -269,13 +276,14 @@ if( arg ) {
 }
 return a+b+c;
 """, TypeInteger.constant(1));
-        StopNode ret = parser.parse().iterate();
-        assertEquals("return 6;", ret.toString());
+        code.parse().opto();
+        assertEquals("return 6;", code.print());
     }
 
     @Test
     public void testDemo2arg2() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
+arg=2;
 int a = 0;
 int b = 1;
 int c = 0;
@@ -287,8 +295,8 @@ if( arg ) {
 }
 return a+b+c;
 """, TypeInteger.constant(2));
-        StopNode ret = parser.parse().iterate();
-        assertEquals("return 5;", ret.toString());
+        code.parse().opto();
+        assertEquals("return 5;", code.print());
     }
 
 }
diff --git a/src/test/java/com/seaofnodes/simple/Chapter07Test.java b/src/test/java/com/seaofnodes/simple/Chapter07Test.java
index 355bbba4..7cef0d9c 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter07Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter07Test.java
@@ -9,7 +9,7 @@ public class Chapter07Test {
 
     @Test
     public void testExample() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 while(arg < 10) {
     arg = arg + 1;
@@ -17,15 +17,15 @@ while(arg < 10) {
 return arg;
 """);
         Node._disablePeephole = true;
-        StopNode stop = parser.parse();
-        assertEquals("return Phi(Loop,arg,(Phi_arg+1));", stop.toString());
-        assertTrue(stop.ret().ctrl() instanceof CProjNode);
+        code.parse();
+        assertEquals("return Phi(Loop,arg,(Phi_arg+1));", code.print());
+        assertTrue(code.ctrl() instanceof CProjNode);
         Node._disablePeephole = false;
     }
 
     @Test
     public void testRegression() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 int a = 1;
 if(arg){}else{
@@ -35,13 +35,13 @@ if(arg){}else{
 }
 return a;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Region,1,Phi(Loop,1,(Phi_a+1)));", stop.toString());
+        code.parse().opto();
+        assertEquals("return Phi(Region,1,Phi(Loop,1,(Phi_a+1)));", code.print());
     }
 
     @Test
     public void testWhileNested() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 int sum = 0;
 int i = 0;
@@ -55,13 +55,13 @@ while(i < arg) {
 }
 return sum;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Loop,0,Phi(Loop,Phi_sum,(Phi_sum+Phi(Loop,0,(Phi_j+1)))));", stop.toString());
+        code.parse().opto();
+        assertEquals("return Phi(Loop,0,Phi(Loop,Phi_sum,(Phi_sum+Phi(Loop,0,(Phi_j+1)))));", code.print());
     }
 
     @Test
     public void testWhileScope() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 int a = 1;
 int b = 2;
@@ -72,15 +72,15 @@ while(a < 10) {
 return b;
 """);
         Node._disablePeephole = true;
-        StopNode stop = parser.parse();
-        assertEquals("return Phi(Loop,2,Phi(Region,Phi_b,4));", stop.toString());
-        assertTrue(stop.ret().ctrl() instanceof CProjNode);
+        code.parse();
+        assertEquals("return Phi(Loop,2,Phi(Region,Phi_b,4));", code.print());
+        assertTrue(code.ctrl() instanceof CProjNode);
         Node._disablePeephole = false;
     }
 
     @Test
     public void testWhileNestedIfAndInc() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 int a = 1;
 int b = 2;
@@ -92,15 +92,15 @@ while(a < 10) {
 }
 return b;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Loop,2,(Phi(Region,Phi_b,4)+1));", stop.toString());
-        assertTrue(stop.ret().ctrl() instanceof CProjNode);
+        code.parse().opto();
+        assertEquals("return Phi(Loop,2,(Phi(Region,Phi_b,4)+1));", code.print());
+        assertTrue(code.ctrl() instanceof CProjNode);
     }
 
 
     @Test
     public void testWhile() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 int a = 1;
 while(a < 10) {
@@ -110,15 +110,15 @@ while(a < 10) {
 return a;
 """);
         Node._disablePeephole = true;
-        StopNode stop = parser.parse();
-        assertEquals("return Phi(Loop,1,((Phi_a+1)+2));", stop.toString());
-        assertTrue(stop.ret().ctrl() instanceof CProjNode);
+        code.parse();
+        assertEquals("return Phi(Loop,1,(Phi_a+3));", code.print());
+        assertTrue(code.ctrl() instanceof CProjNode);
         Node._disablePeephole = false;
     }
 
     @Test
     public void testWhilePeep() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 int a = 1;
 while(a < 10) {
@@ -127,42 +127,42 @@ while(a < 10) {
 }
 return a;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Loop,1,(Phi_a+3));", stop.toString());
-        assertTrue(stop.ret().ctrl() instanceof CProjNode);
+        code.parse().opto();
+        assertEquals("return Phi(Loop,1,(Phi_a+3));", code.print());
+        assertTrue(code.ctrl() instanceof CProjNode);
     }
 
     @Test
     public void testWhile2() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 int a = 1;
 while(arg) a = 2;
 return a;
 """);
         Node._disablePeephole = true;
-        StopNode stop = parser.parse();
-        assertEquals("return Phi(Loop,1,2);", stop.toString());
-        assertTrue(stop.ret().ctrl() instanceof CProjNode);
+        code.parse();
+        assertEquals("return Phi(Loop,1,2);", code.print());
+        assertTrue(code.ctrl() instanceof CProjNode);
         Node._disablePeephole = false;
     }
 
     @Test
     public void testWhile2Peep() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 int a = 1;
 while(arg) a = 2;
 return a;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Loop,1,2);", stop.toString());
-        assertTrue(stop.ret().ctrl() instanceof CProjNode);
+        code.parse().opto();
+        assertEquals("return Phi(Loop,1,2);", code.print());
+        assertTrue(code.ctrl() instanceof CProjNode);
     }
 
     @Test
     public void testWhile3() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 int a = 1;
 while(a < 10) {
@@ -172,15 +172,15 @@ while(a < 10) {
 return a;
 """);
         Node._disablePeephole = true;
-        StopNode stop = parser.parse();
-        assertEquals("return Phi(Loop,1,((Phi_a+1)+2));", stop.toString());
-        assertTrue(stop.ret().ctrl() instanceof CProjNode);
+        code.parse();
+        assertEquals("return Phi(Loop,1,(Phi_a+3));", code.print());
+        assertTrue(code.ctrl() instanceof CProjNode);
         Node._disablePeephole = false;
     }
 
     @Test
     public void testWhile3Peep() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 int a = 1;
 while(a < 10) {
@@ -189,14 +189,14 @@ while(a < 10) {
 }
 return a;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Loop,1,(Phi_a+3));", stop.toString());
-        assertTrue(stop.ret().ctrl() instanceof CProjNode);
+        code.parse().opto();
+        assertEquals("return Phi(Loop,1,(Phi_a+3));", code.print());
+        assertTrue(code.ctrl() instanceof CProjNode);
     }
 
     @Test
     public void testWhile4() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 int a = 1;
 int b = 2;
@@ -207,15 +207,15 @@ while(a < 10) {
 return a;
 """);
         Node._disablePeephole = true;
-        StopNode stop = parser.parse();
-        assertEquals("return Phi(Loop,1,((Phi_a+1)+2));", stop.toString());
-        assertTrue(stop.ret().ctrl() instanceof CProjNode);
+        code.parse();
+        assertEquals("return Phi(Loop,1,(Phi_a+3));", code.print());
+        assertTrue(code.ctrl() instanceof CProjNode);
         Node._disablePeephole = false;
     }
 
     @Test
     public void testWhile4Peep() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 int a = 1;
 int b = 2;
@@ -225,9 +225,9 @@ while(a < 10) {
 }
 return a;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Loop,1,(Phi_a+3));", stop.toString());
-        assertTrue(stop.ret().ctrl() instanceof CProjNode);
+        code.parse().opto();
+        assertEquals("return Phi(Loop,1,(Phi_a+3));", code.print());
+        assertTrue(code.ctrl() instanceof CProjNode);
     }
 
 }
diff --git a/src/test/java/com/seaofnodes/simple/Chapter08Test.java b/src/test/java/com/seaofnodes/simple/Chapter08Test.java
index bb3bd674..03a2c50a 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter08Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter08Test.java
@@ -2,6 +2,7 @@ package com.seaofnodes.simple;
 
 import com.seaofnodes.simple.evaluator.Evaluator;
 import com.seaofnodes.simple.node.*;
+import com.seaofnodes.simple.type.TypeInteger;
 import org.junit.Assert;
 import org.junit.Test;
 
@@ -11,7 +12,7 @@ public class Chapter08Test {
 
     @Test
     public void testEx6() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
                 """
 while(arg < 10) {
     arg = arg + 1;
@@ -22,17 +23,17 @@ while(arg < 10) {
 }
 return arg;
                 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Region,Phi(Region,Phi(Loop,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));
+        code.parse().opto();
+        assertEquals("return Phi(Region,Phi(Region,Phi(Loop,arg,(Phi_arg+1)),Add),Add);", code.print());
+        assertTrue(code.ctrl() instanceof RegionNode);
+        Assert.assertEquals( "5", Eval2.eval(code, 1));
+        Assert.assertEquals("10", Eval2.eval(code, 6));
     }
 
 
     @Test
     public void testEx5() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
                 """
 int a = 1;
 while(arg < 10) {
@@ -45,15 +46,15 @@ while(arg < 10) {
 }
 return a;
                 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Loop,1,Phi(Region,Phi_a,(Phi_a+1)));", stop.toString());
-        assertTrue(stop.ret().ctrl() instanceof CProjNode);
+        code.parse().opto();
+        assertEquals("return Phi(Loop,1,Phi(Region,Phi_a,(Phi_a+1)));", code.print());
+        assertTrue(code.ctrl() instanceof CProjNode);
     }
 
 
     @Test
     public void testEx4() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
                 """
 while(arg < 10) {
     arg = arg + 1;
@@ -64,14 +65,14 @@ while(arg < 10) {
 }
 return arg;
                 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Region,Phi(Loop,arg,(Phi_arg+1)),Add);", stop.toString());
-        assertTrue(stop.ret().ctrl() instanceof RegionNode);
+        code.parse().opto();
+        assertEquals("return Phi(Region,Phi(Loop,arg,(Phi_arg+1)),Add);", code.print());
+        assertTrue(code.ctrl() instanceof RegionNode);
     }
 
     @Test
     public void testEx3() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
                 """
 while(arg < 10) {
     arg = arg + 1;
@@ -80,15 +81,15 @@ while(arg < 10) {
 }
 return arg;
                 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Region,Phi(Loop,arg,(Phi_arg+1)),Add);", stop.toString());
-        assertTrue(stop.ret().ctrl() instanceof RegionNode);
+        code.parse().opto();
+        assertEquals("return Phi(Region,Phi(Loop,arg,(Phi_arg+1)),Add);", code.print());
+        assertTrue(code.ctrl() instanceof RegionNode);
     }
 
 
     @Test
     public void testEx2() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
                 """
 while(arg < 10) {
     arg = arg + 1;
@@ -99,15 +100,15 @@ while(arg < 10) {
 }
 return arg;
                 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Loop,arg,(Phi_arg+1));", stop.toString());
-        assertTrue(stop.ret().ctrl() instanceof CProjNode);
+        code.parse().opto();
+        assertEquals("return Phi(Loop,arg,(Phi_arg+1));", code.print());
+        assertTrue(code.ctrl() instanceof CProjNode);
     }
 
 
     @Test
     public void testEx1() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
                 """
 while(arg < 10) {
     arg = arg + 1;
@@ -116,14 +117,14 @@ while(arg < 10) {
 }
 return arg;
                 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Loop,arg,(Phi_arg+1));", stop.toString());
-        assertTrue(stop.ret().ctrl() instanceof CProjNode);
+        code.parse().opto();
+        assertEquals("return Phi(Loop,arg,(Phi_arg+1));", code.print());
+        assertTrue(code.ctrl() instanceof CProjNode);
     }
 
     @Test
     public void testRegress1() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
                 """
 while( arg < 10 ) {
     int a = arg+2;
@@ -132,15 +133,15 @@ while( arg < 10 ) {
 }
 return arg;
                 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return arg;", stop.toString());
+        code.parse().opto();
+        assertEquals("return arg;", code.print());
     }
 
     @Test
     public void testRegress2() {
-        Parser parser = new Parser("if(1) return 0;  else while(arg>- -arg) arg=arg+1; return 0;");
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 0;", stop.toString());
+        CodeGen code = new CodeGen("if(1) return 0;  else while(arg>- -arg) arg=arg+1; return 0;");
+        code.parse().opto();
+        assertEquals("return 0;", code.print());
     }
 
     @Test
@@ -161,19 +162,19 @@ return arg;
 
     @Test
     public void testRegress3() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 while(arg < 10) {
     break;
 }
 return arg;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return arg;", stop.toString());
+        code.parse().opto();
+        assertEquals("return arg;", code.print());
     }
 
     @Test
     public void testRegress4() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 int a = 1;
 while(arg < 10) {
     a = a + 1;
@@ -184,14 +185,14 @@ while(arg < 10) {
 }
 return a;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Region,Phi(Loop,1,(Phi_a+1)),Add);", stop.toString());
-        assertTrue(stop.ret().ctrl() instanceof RegionNode);
+        code.parse().opto();
+        assertEquals("return Phi(Region,Phi(Loop,1,(Phi_a+1)),Add);", code.print());
+        assertTrue(code.ctrl() instanceof RegionNode);
     }
 
     @Test
     public void testRegress5() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 int a = 1;
 while(1) {
     a = a + 1;
@@ -200,9 +201,9 @@ while(1) {
 }
 return a;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return (Phi(Loop,1,Add)+1);", stop.toString());
-        assertTrue(stop.ret().ctrl() instanceof CProjNode prj && prj._idx==1 );
+        code.parse().opto();
+        assertEquals("return (Phi(Loop,1,Add)+1);", code.print());
+        assertTrue(code.ctrl() instanceof CProjNode prj && prj._idx==1 );
     }
 
 }
diff --git a/src/test/java/com/seaofnodes/simple/Chapter09Test.java b/src/test/java/com/seaofnodes/simple/Chapter09Test.java
index c31afcd6..b210f7e9 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter09Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter09Test.java
@@ -1,7 +1,6 @@
 package com.seaofnodes.simple;
 
 import com.seaofnodes.simple.evaluator.Evaluator;
-import com.seaofnodes.simple.node.*;
 import com.seaofnodes.simple.type.Type;
 import com.seaofnodes.simple.type.TypeInteger;
 import org.junit.Assert;
@@ -15,7 +14,7 @@ public class Chapter09Test {
     @Test
     @Ignore
     public void testJig() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 int v0=0;
 arg=0;
 while(v0) {
@@ -25,12 +24,12 @@ while(v0) {
 }
 return 0;
                 """);
-        StopNode stop = parser.parse().iterate();
+        code.parse().opto();
     }
 
     @Test
     public void testGVN1() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
                 """
 int x = arg + arg;
 if(arg < 10) {
@@ -41,41 +40,37 @@ else {
 }
 return x;
                 """);
-        StopNode stop = parser.parse();
-        assertEquals("Stop[ return (arg*2); return (Mul+1); ]", stop.toString());
-        Assert.assertEquals(2L, Evaluator.evaluate(stop, 1));
-        Assert.assertEquals(23L, Evaluator.evaluate(stop, 11));
+        code.parse().opto();
+        assertEquals("return Phi(Region,(arg*2),(Mul+1));", code.print());
+        Assert.assertEquals( "2", Eval2.eval(code,  1));
+        Assert.assertEquals("23", Eval2.eval(code, 11));
     }
 
     @Test
     public void testGVN2() {
-        Parser parser = new Parser(
-                """
-return arg*arg-arg*arg;
-                """);
-        StopNode stop = parser.parse();
-        assertEquals("return 0;", stop.toString());
-        Assert.assertEquals(0L, Evaluator.evaluate(stop, 1));
+        CodeGen code = new CodeGen("return arg*arg-arg*arg;");
+        code.parse().opto();
+        assertEquals("return 0;", code.print());
+        Assert.assertEquals("0", Eval2.eval(code,  1, 1));
     }
 
     @Test
     public void testWorklist1() {
-        Parser parser = new Parser(
-                """
+        CodeGen code = new CodeGen("""
 int step = 1;
 while (arg < 10) {
     arg = arg + step + 1;
 }
 return arg;
-                """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Loop,arg,(Phi_arg+2));", stop.toString());
-        Assert.assertEquals(11L, Evaluator.evaluate(stop, 1));
+""");
+        code.parse().opto();
+        assertEquals("return Phi(Loop,arg,(Phi_arg+2));", code.print());
+        Assert.assertEquals("11", Eval2.eval(code,  1));
     }
 
     @Test
     public void testWorklist2() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
                 """
 int cond = 0;
 int one = 1;
@@ -85,14 +80,14 @@ while (arg < 10) {
 }
 return arg;
                 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Loop,arg,(Phi_arg+4));", stop.toString());
-        Assert.assertEquals(13L, Evaluator.evaluate(stop, 1));
+        code.parse().opto();
+        assertEquals("return Phi(Loop,arg,(Phi_arg+4));", code.print());
+        Assert.assertEquals("13", Eval2.eval(code,  1));
     }
 
     @Test
     public void testWorklist3() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
                 """
 int v1 = 0;
 int v2 = 0;
@@ -114,13 +109,13 @@ while (arg) {
 }
 return arg;
                 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 0;", stop.toString());
+        code.parse().opto();
+        assertEquals("return 0;", code.print());
     }
 
     @Test
     public void testRegionPeepBug() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
                 """
 int v0=0;
 int v1=0;
@@ -132,48 +127,48 @@ while(v1+arg) {
     v1=v2;
 }
                 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("Stop[ return 0; return 0; ]", stop.toString());
+        code.parse().opto();
+        assertEquals("return 0;", code.print());
     }
 
     @Test
     public void testWhile0() {
-        Parser parser = new Parser("while(0) continue; if(0) arg=0;");
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 0;", stop.toString());
+        CodeGen code = new CodeGen("while(0) continue; if(0) arg=0;");
+        code.parse().opto();
+        assertEquals("return 0;", code.print());
     }
 
     @Test
     public void testWhile1() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 if(0) while(0) {
     int arg=arg;
     while(0) {}
 }
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 0;", stop.toString());
+        code.parse().opto();
+        assertEquals("return 0;", code.print());
     }
 
 
     @Test
     public void testPrecedence() {
-        Parser parser = new Parser("return 3-1+2;");
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 4;", stop.toString());
+        CodeGen code = new CodeGen("return 3-1+2;");
+        code.parse().opto();
+        assertEquals("return 4;", code.print());
     }
 
     @Test
     public void testSwap2() {
-        Parser parser = new Parser("return 1+(1+1);");
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 3;", stop.toString());
+        CodeGen code = new CodeGen("return 1+(1+1);");
+        code.parse().opto();
+        assertEquals("return 3;", code.print());
     }
 
 
     @Test
     public void testFuzz0() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 int one = 1;
 int a = 0;
 int zero = 0;
@@ -184,13 +179,13 @@ while(arg) {
 }
 return a;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Loop,0,(-(Phi_a+3)));", stop.toString());
+        code.parse().opto();
+        assertEquals("return Phi(Loop,0,(-(Phi_a+3)));", code.print());
     }
 
     @Test
     public void testFuzz1() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 while(1) {}
 while(arg) break;
 while(arg) arg=0;
@@ -198,40 +193,40 @@ arg=0;
 int v0=0!=0<-0;
 return -0+0+0;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 0;", stop.toString());
+        code.parse().opto();
+        assertEquals("return Top;", code.print());
     }
 
 
     @Test
     public void testFuzz2() {
-        Parser parser = new Parser("return 0+-0;");
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 0;", stop.toString());
+        CodeGen code = new CodeGen("return 0+-0;");
+        code.parse().opto();
+        assertEquals("return 0;", code.print());
     }
 
     @Test
     public void testFuzz3() {
-        Parser parser = new Parser("int v0=0; while(0==69) while(v0) return 0;");
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 0;", stop.toString());
+        CodeGen code = new CodeGen("int v0=0; while(0==69) while(v0) return 0;");
+        code.parse().opto();
+        assertEquals("return 0;", code.print());
     }
 
     @Test
     public void testFuzz4() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 while(1) {
     arg=0<=0;
     if(1<0) while(arg==-0) arg=arg-arg;
 }
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 0;", stop.toString());
+        code.parse().opto();
+        assertEquals("return Top;", code.print());
     }
 
     @Test
     public void testFuzz5() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 {
     int v0=0;
     while(1)
@@ -247,25 +242,25 @@ while(1) {
 }
 return 0!=0;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 0;", stop.toString());
+        code.parse().opto();
+        assertEquals("return Top;", code.print());
     }
 
     @Test
     public void testFuzz6() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 int v0=0;
 while(0==1) while(v0)
         v0=1+v0;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 0;", stop.toString());
+        code.parse().opto();
+        assertEquals("return ~int;", code.print());
     }
 
     @Test
     public void testFuzz7() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 while(1) {}
 int v0=0;
 while(v0)
@@ -275,15 +270,15 @@ while(1)
         v1=1;
 return v1+v0;
                                    """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 0;", stop.toString());
+        code.parse().opto();
+        assertEquals("return Top;", code.print());
     }
 
     @Test
     public void testFuzz8() {
-        Parser parser = new Parser("while(arg) arg = arg - 1;  return arg;");
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 0;", stop.toString());
+        CodeGen code = new CodeGen("while(arg) arg = arg - 1;  return arg;");
+        code.parse().opto();
+        assertEquals("return 0;", code.print());
     }
 
     @Test
diff --git a/src/test/java/com/seaofnodes/simple/Chapter10Test.java b/src/test/java/com/seaofnodes/simple/Chapter10Test.java
index d41c83d8..02029b3f 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter10Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter10Test.java
@@ -1,7 +1,5 @@
 package com.seaofnodes.simple;
 
-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.fail;
@@ -10,7 +8,7 @@ public class Chapter10Test {
 
     @Test
     public void testFuzzer() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 int a = arg/3;
 int b = arg*5;
@@ -29,13 +27,13 @@ if( (arg/13)==0 ) {
 int r = g+h;
 return p-r;
 """);
-        StopNode stop = parser.parse(false).iterate(false);
-        assertEquals("return 0;", stop.toString());
+        code.parse().opto();
+        assertEquals("return 0;", code.print());
     }
 
     @Test
     public void testStruct() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 struct Bar {
     int a;
     int b;
@@ -49,13 +47,13 @@ bar.a = 1;
 bar.a = 2;
 return bar.a;
 """);
-        StopNode stop = parser.parse(false).iterate();
-        assertEquals("return 2;", stop.toString());
+        code.parse().opto();
+        assertEquals("return 2;", code.print());
     }
 
     @Test
     public void testExample() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 struct Vector2D { int x; int y; };
 Vector2D !v = new Vector2D;
 v.x = 1;
@@ -65,36 +63,36 @@ else
     v.y = 3;
 return v;
 """);
-        StopNode stop = parser.parse(false).iterate();
-        assertEquals("return Vector2D;", stop.toString());
+        code.parse().opto();
+        assertEquals("return Vector2D;", code.print());
     }
 
     @Test
     public void testBug() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 struct s0 {
     int v0;
 };
 s0? v1=null;
 int v3=v1.zAicm;
 """);
-        try { parser.parse();  fail(); }
+        try { code.parse();  fail(); }
         catch( Exception e ) {  assertEquals("Accessing unknown field 'zAicm' from 'null'",e.getMessage());  }
     }
 
     @Test
     public void testBug2() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 struct s0 { int v0; };
 arg=0+new s0.0;
 """);
-        try { parser.parse(); fail(); }
+        try { code.parse(); fail(); }
         catch( Exception e ) { assertEquals("Expected an identifier, found 'null'",e.getMessage()); }
     }
 
     @Test
     public void testLoop() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 struct Bar { int a; };
 Bar !bar = new Bar;
 while (arg) {
@@ -103,65 +101,65 @@ while (arg) {
 }
 return bar.a;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Loop,0,(Phi_a+2));", stop.toString());
+        code.parse().opto();
+        assertEquals("return Phi(Loop,0,(Phi_a+2));", code.print());
     }
 
     @Test
     public void testIf() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 struct Bar { int a; };
 Bar !bar = new Bar;
 if (arg) bar = null;
 bar.a = 1;
 return bar.a;
 """);
-        try { parser.parse().iterate(); fail(); }
+        try { code.parse().opto(); fail(); }
         catch( Exception e ) { assertEquals("Type null is not of declared type *Bar",e.getMessage()); }
     }
 
     @Test
     public void testIf2() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 struct Bar { int a; };
 Bar? !bar = null;
 if (arg) bar = new Bar;
 bar.a = 1;
 return bar.a;
 """);
-        try { parser.parse().iterate(); fail(); }
+        try { code.parse().opto().typeCheck(); fail(); }
         catch( Exception e ) { assertEquals("Might be null accessing 'a'",e.getMessage()); }
     }
 
     @Test
     public void testIf3() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 struct Bar { int a; };
 Bar bar = null;
 if (arg) bar = null;
 bar.a = 1;
 return bar.a;
 """);
-        try { parser.parse(); fail(); }
+        try { code.parse(); fail(); }
         catch( Exception e ) { assertEquals("Type null is not of declared type *Bar", e.getMessage()); }
     }
 
     @Test
     public void testIfOrNull() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 struct Bar { int a; };
 Bar? !bar = new Bar;
 if (arg) bar = null;
 if( bar ) bar.a = 1;
 return bar;
 """);
-        StopNode stop = parser.parse(false).iterate();
-        assertEquals("return Phi(Region,(*void)Phi(Region,null,Bar),null);", stop.toString());
+        code.parse().opto();
+        assertEquals("return Phi(Region,null,Bar);", code.print());
     }
 
     @Test
     public void testIfOrNull2() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 struct Bar { int a; };
 Bar? !bar = new Bar;
@@ -171,13 +169,13 @@ if( !bar ) rez=4;
 else bar.a = 1;
 return rez;
 """);
-        StopNode stop = parser.parse(false).iterate();
-        assertEquals("return Phi(Region,4,3);", stop.toString());
+        code.parse().opto();
+        assertEquals("return Phi(Region,4,3);", code.print());
     }
 
     @Test
     public void testWhileWithNullInside() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 struct s0 {int v0;};
 s0? !v0 = new s0;
 int ret = 0;
@@ -188,14 +186,14 @@ while(arg) {
 }
 return ret;
 """);
-        try { parser.parse().iterate(); fail(); }
+        try { code.parse().opto().typeCheck(); fail(); }
         catch( Exception e ) {
             assertEquals("Might be null accessing 'v0'", e.getMessage()); }
     }
 
     @Test
     public void testRedeclareStruct() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 struct s0 {
     int v0;
 };
@@ -203,14 +201,14 @@ s0? v1=new s0;
 s0? v1;
 v1=new s0;
 """);
-        try { parser.parse(); fail(); }
+        try { code.parse(); fail(); }
         catch( Exception e ) { assertEquals("Redefining name 'v1'", e.getMessage()); }
     }
 
     @Test
     public void testIter() {
         // Build and use an iterator
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 struct Iter {
     int x;
@@ -225,14 +223,14 @@ while( i.x < i.len ) {
 }
 return sum;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Loop,0,(Phi(Loop,0,(Phi_x+1))+Phi_sum));", stop.toString());
+        code.parse().opto();
+        assertEquals("return Phi(Loop,0,(Phi(Loop,0,(Phi_x+1))+Phi_sum));", code.print());
     }
 
 
     @Test
     public void test1() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 struct s0 {int v0;};
 s0 !ret = new s0;
 while(arg) {
@@ -244,13 +242,13 @@ while(arg) {
 }
 return ret;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Loop,s0,Phi(Region,s0,Phi_ret));", stop.toString());
+        code.parse().opto();
+        assertEquals("return Phi(Loop,s0,Phi(Region,s0,Phi_ret));", code.print());
     }
 
     @Test
     public void test2() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 struct s0 {int v0;};
 s0 !ret = new s0;
 s0 !v0 = new s0;
@@ -262,14 +260,14 @@ while(arg) {
 }
 return ret;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Loop,s0,Phi(Region,s0,Phi_ret));", stop.toString());
+        code.parse().opto();
+        assertEquals("return Phi(Loop,s0,Phi(Region,s0,Phi_ret));", code.print());
     }
 
 
     @Test
     public void test3() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 struct s0 {int v0;};
 s0 !ret = new s0;
 while(arg < 10) {
@@ -279,41 +277,40 @@ while(arg < 10) {
 }
 return ret;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Loop,s0,Phi(Region,s0,Phi_ret));", stop.toString());
+        code.parse().opto();
+        assertEquals("return Phi(Loop,s0,Phi(Region,s0,Phi_ret));", code.print());
     }
 
     @Test
     public void testBug3() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 struct s0 { int f0; };
 return new s0;
 int v0=null.f0;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return s0;", stop.toString());
-        assertEquals("Obj<s0>{f0=0}", Evaluator.evaluate(stop, 0).toString());
+        try { code.parse();  fail(); }
+        catch( Exception e ) {  assertEquals("Accessing unknown field 'f0' from 'null'",e.getMessage());  }
     }
 
     @Test
     public void testBug4() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 if(0) {
     while(0) if(arg) continue;
     int v0=0;
     while(1) {
-        int arg=-arg;
-        v0=arg;
+        int v2=-arg;
+        v0=v2;
     }
 }
    """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 0;", stop.toString());
+        code.parse().opto();
+        assertEquals("return 0;", code.print());
     }
 
     @Test
     public void testBug5() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 struct s0 {
     int f0;
 };
@@ -321,13 +318,13 @@ if(0) return 0;
 else return new s0;
 if(new s0.f0) return 0;
     """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return s0;", stop.toString());
+        code.parse().opto();
+        assertEquals("return s0;", code.print());
     }
 
     @Test
     public void testBug6MissedWorklist() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 while(0) {}
 int v4=0;
 while(0<arg) {
@@ -337,26 +334,26 @@ while(0<arg) {
 }
 return 0;
     """);
-        StopNode stop = parser.parse().iterate();
+        code.parse().opto();
     }
 
     @Test
     public void testBug7() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 struct s0 {  int f0; };
 s0 v0 = new s0;
 while(v0.f0) {}
 s0 v1 = v0;
 return v1;
     """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return (const)s0;", stop.toString());
+        code.parse().opto();
+        assertEquals("return (const)s0;", code.print());
     }
 
 
     @Test
     public void testBug8() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 int v2=0;
 while(0)
 while(0) {}
@@ -381,19 +378,19 @@ while(0) {}
         }    }
 }
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 0;", stop.toString());
+        code.parse().opto();
+        assertEquals("return 0;", code.print());
     }
 
     @Test
     public void testBug9() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 int v0=arg==0;
 while(v0) continue;
 return 0;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 0;", stop.toString());
+        code.parse().opto();
+        assertEquals("return 0;", code.print());
     }
 
 }
diff --git a/src/test/java/com/seaofnodes/simple/Chapter11Test.java b/src/test/java/com/seaofnodes/simple/Chapter11Test.java
index 613b979b..0b24bd5d 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter11Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter11Test.java
@@ -1,7 +1,5 @@
 package com.seaofnodes.simple;
 
-import com.seaofnodes.simple.evaluator.Evaluator;
-import com.seaofnodes.simple.node.StopNode;
 import org.junit.Test;
 
 
@@ -12,7 +10,7 @@ public class Chapter11Test {
     // A placeholder test used to rapidly rotate through fuzzer produced issues
     @Test
     public void testFuzzer() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 while(---- -arg) {
     while(-arg) {
@@ -291,14 +289,14 @@ else {
         }
 }
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("Stop[ return 9; return 0; return 0; return 0; return 0; ]", stop.toString());
+        code.parse().opto().typeCheck().GCM();
+        assertEquals("return Phi(Region,9,Top,Top,Top,Top);", code.print());
     }
 
 
     @Test
     public void testPrimes() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 if( arg < 2 ) return 0;
 int primeCount = 1;
@@ -323,19 +321,19 @@ while( prime <= arg ) {
 }
 return primeCount;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("Stop[ return 0; return Phi(Loop,1,Phi(Region,Phi_primeCount,Phi(Region,(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
+        code.parse().opto();
+        assertEquals("return Phi(Region,0,Phi(Loop,1,Phi(Region,Phi_primeCount,Phi(Region,(Phi_primeCount+1),Phi_primeCount))));", code.print());
+        assertEquals("0", Eval2.eval(code,  1)); // No primes 1 or below
+        assertEquals("1", Eval2.eval(code,  2)); // 2
+        assertEquals("2", Eval2.eval(code,  3)); // 2, 3
+        assertEquals("2", Eval2.eval(code,  4)); // 2, 3
+        assertEquals("3", Eval2.eval(code,  5)); // 2, 3, 5
+        assertEquals("4", Eval2.eval(code, 10)); // 2, 3, 5, 7
     }
 
     @Test
     public void testAntiDeps1() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 struct S { int f; };
 S !v=new S;
@@ -345,15 +343,15 @@ i=v.f;
 if (arg) v.f=1;
 return i;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 2;", stop.toString());
-        assertEquals(2L, Evaluator.evaluate(stop, 0));
-        assertEquals(2L, Evaluator.evaluate(stop, 1));
+        code.parse().opto();
+        assertEquals("return 2;", code.print());
+        assertEquals("2", Eval2.eval(code, 0));
+        assertEquals("2", Eval2.eval(code, 1));
     }
 
     @Test
     public void testAntiDeps2() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 struct S { int f; };
 S !v = new S;
@@ -368,13 +366,13 @@ if (arg) {
 }
 return i;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Region,.f,0);", stop.toString());
+        code.parse().opto();
+        assertEquals("return Phi(Region,.f,0);", code.print());
     }
 
     @Test
     public void testAntiDeps3() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 struct S { int f; };
 S !v0 = new S;
@@ -387,14 +385,14 @@ if (v1) {
 }
 return v0;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return S;", stop.toString());
+        code.parse().opto();
+        assertEquals("return S;", code.print());
     }
 
 
     @Test
     public void testAntiDeps4() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 struct S { int f; };
 S !v = new S;
@@ -405,13 +403,13 @@ if (arg+1) arg= 0;
 while (arg) v.f = 2;
 return i;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return arg;", stop.toString());
+        code.parse().opto();
+        assertEquals("return arg;", code.print());
     }
 
     @Test
     public void testAntiDeps5() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 struct S { int f; };
 S !v = new S;
@@ -422,13 +420,13 @@ while(1) {
 }
 return v;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return S;", stop.toString());
+        code.parse().opto();
+        assertEquals("return S;", code.print());
     }
 
     @Test
     public void testAntiDeps6() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 struct s { int v; };
 s !ptr=new s;
@@ -437,13 +435,13 @@ while( -arg )
 while(1)
   arg = arg+ptr.v;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 0;", stop.toString());
+        code.parse().opto();
+        assertEquals("return Top;", code.print());
     }
 
     @Test
     public void testAntiDeps7() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 struct S { int f; };
 S !v = new S;
@@ -455,13 +453,13 @@ while (arg) {
 }
 return i;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 0;", stop.toString());
+        code.parse().opto();
+        assertEquals("return 0;", code.print());
     }
 
     @Test
     public void testAntiDeps8() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 struct S { int f; };
 S !v = new S;
@@ -475,13 +473,13 @@ while(arg) {
 }
 return arg;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 0;", stop.toString());
+        code.parse().opto();
+        assertEquals("return 0;", code.print());
     }
 
     @Test
     public void testAntiDeps9() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 struct S { int f; };
 S !v = new S;
@@ -493,13 +491,13 @@ if (arg) {
 }
 return v;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return S;", stop.toString());
+        code.parse().opto();
+        assertEquals("return S;", code.print());
     }
 
     @Test
     public void testExample2() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 struct S { int f; };
 S !v = new S;
@@ -512,13 +510,13 @@ while (arg > 0) {
 }
 return v;
                 """);
-        StopNode stop = parser.parse().iterate();
-        //assertEquals("return new S;", stop.toString());
+        code.parse().opto();
+        //assertEquals("return new S;", code.print());
     }
 
     @Test
     public void testScheduleUse() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 int v0=0;
 while(0>=0) {
@@ -529,13 +527,13 @@ while(0>=0) {
 }
 return 0;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 0;", stop.toString());
+        code.parse().opto();
+        assertEquals("return Top;", code.print());
     }
 
     @Test
     public void testLoopCarriedDep() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 u32 v0=0;
 {
@@ -544,10 +542,11 @@ u32 v0=0;
         v1=1>>>v0!=0;
         v0=v1/0;
     }
+    return v1;
 }
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 0;", stop.toString());
+        code.parse().opto();
+        assertEquals("return 0;", code.print());
     }
 
 }
diff --git a/src/test/java/com/seaofnodes/simple/Chapter12Test.java b/src/test/java/com/seaofnodes/simple/Chapter12Test.java
index a70a5f33..21df8205 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter12Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter12Test.java
@@ -10,29 +10,29 @@ import static org.junit.Assert.fail;
 public class Chapter12Test {
     @Test
     public void testJig() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 return 3.14;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 3.14;", stop.toString());
-        assertEquals(3.14, Evaluator.evaluate(stop,  0));
+        code.parse().opto();
+        assertEquals("return 3.14;", code.print());
+        assertEquals("3.14", Eval2.eval(code,  0));
     }
 
     @Test
     public void testFloat() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 return 3.14;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 3.14;", stop.toString());
-        assertEquals(3.14, Evaluator.evaluate(stop,  0));
+        code.parse().opto();
+        assertEquals("return 3.14;", code.print());
+        assertEquals("3.14", Eval2.eval(code,  0));
     }
 
     @Test
     public void testSquareRoot() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 flt guess = arg;
 while( 1 ) {
@@ -42,21 +42,21 @@ while( 1 ) {
 }
 return guess;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Loop,(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));
+        code.parse().opto();
+        assertEquals("return Phi(Loop,(flt)arg,(((ToFloat/Phi_guess)+Phi_guess)/2.0f));", code.print());
+        assertEquals("3.0", Eval2.eval(code,  9));
+        assertEquals("1.414213562373095", Eval2.eval(code,  2));
     }
 
     @Test
     public void testFPOps() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 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));
+        code.parse().opto();
+        assertEquals("return ((flt)arg==(ToFloat+1.0f));", code.print());
+        assertEquals("0", Eval2.eval(code, 1));
     }
 }
diff --git a/src/test/java/com/seaofnodes/simple/Chapter13Test.java b/src/test/java/com/seaofnodes/simple/Chapter13Test.java
index 30d9b147..6aa64bf9 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter13Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter13Test.java
@@ -1,7 +1,5 @@
 package com.seaofnodes.simple;
 
-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.fail;
@@ -9,18 +7,18 @@ import static org.junit.Assert.fail;
 public class Chapter13Test {
     @Test
     public void testJig() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 return 3.14;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 3.14;", stop.toString());
-        assertEquals(3.14, Evaluator.evaluate(stop,  0));
+        code.parse().opto();
+        assertEquals("return 3.14;", code.print());
+        assertEquals("3.14", Eval2.eval(code,  0));
     }
 
     @Test
     public void testLinkedList0() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 struct LLI { LLI? next; int i; };
 LLI? !head = null;
@@ -33,13 +31,13 @@ while( arg ) {
 }
 return head.next.i;
 """);
-        try { parser.parse().iterate(); fail(); }
+        try { code.parse().opto().typeCheck(); fail(); }
         catch( Exception e ) { assertEquals("Might be null accessing 'i'",e.getMessage()); }
     }
 
     @Test
     public void testLinkedList1() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 struct LLI { LLI? next; int i; };
 LLI? !head = null;
@@ -55,14 +53,14 @@ 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));
+        code.parse().opto();
+        assertEquals("return Phi(Region,0,1,.i);", code.print());
+        assertEquals("2", Eval2.eval(code,  3));
     }
 
     @Test
     public void testCoRecur() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 struct int0 { int i; flt0? f; };
 struct flt0 { flt f; int0? i; };
@@ -74,98 +72,98 @@ i0.f = f0;
 f0.i = i0;
 return f0.i.f.i.i;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 17;", stop.toString());
+        code.parse().opto();
+        assertEquals("return 17;", code.print());
     }
 
     @Test
     public void testNullRef0() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 struct N { N? next; int i; };
 N n = new N;
 return n.next;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return null;", stop.toString());
+        code.parse().opto();
+        assertEquals("return null;", code.print());
     }
 
     @Test
     public void testNullRef1() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 struct M { int m; };
 struct N { M next; int i; };
 N n = new N { next = new M; };
 return n.next;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return (const)M;", stop.toString());
+        code.parse().opto();
+        assertEquals("return (const)M;", code.print());
     }
 
     @Test
     public void testNullRef2() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 struct M { int m; };
 struct N { M next; int i; };
 N n = new N { next = null; }
 return n.next;
 """);
-        try { parser.parse().iterate(); fail(); }
+        try { code.parse().opto(); fail(); }
         catch( Exception e ) { assertEquals("Type null is not of declared type *M",e.getMessage()); }
     }
 
     @Test
     public void testNullRef3() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 struct N { N? next; int i; };
 N !n = new N;
 n.i = 3.14;
 return n.i;
 """);
-        try { parser.parse().iterate(); fail(); }
+        try { code.parse().opto(); fail(); }
         catch( Exception e ) { assertEquals("Type 3.14 is not of declared type int",e.getMessage()); }
     }
 
     @Test
     public void testEmpty() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 struct S{};
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 0;", stop.toString());
-        assertEquals(0L, Evaluator.evaluate(stop,  0));
+        code.parse().opto();
+        assertEquals("return 0;", code.print());
+        assertEquals("0", Eval2.eval(code,  0));
     }
 
     @Test
     public void testForwardRef0() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 struct S1 { S2? s; };
 return new S2;
 """);
-        try { parser.parse().iterate(); fail(); }
+        try { code.parse().opto(); fail(); }
         catch( Exception e ) { assertEquals("Unknown struct type 'S2'",e.getMessage()); }
     }
 
     @Test
     public void testForwardRef1() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 struct S1 { S2? s; };
 struct S2 { int x; };
 return new S1.s=new S2;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return S2;", stop.toString());
+        code.parse().opto();
+        assertEquals("return S2;", code.print());
     }
 
     @Test
     public void testcheckNull() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 struct I {int i;};
 struct P { I? pi; };
@@ -176,8 +174,74 @@ p2.pi.i = 2;
 if (arg) p1 = new P;
 return p1.pi.i + 1;
 """);
-        try { parser.parse(false).iterate();  fail(); }
+        try { code.parse().opto().typeCheck();  fail(); }
         catch( Exception e ) {  assertEquals("Might be null accessing 'i'",e.getMessage());  }
     }
 
+    @Test
+    public void testCoRecur2() {
+        CodeGen code = new CodeGen(
+"""
+struct A { L? a; T? b; F? c; };  A? !a = new A;
+struct B { M? a; U? b; G? c; };  B? !b = new B;
+struct C { N? a; V? b; H? c; };  C? !c = new C;
+struct D { O? a; W? b; I? c; };  D? !d = new D;
+struct E { P? a; X? b; J? c; };  E? !e = new E;
+struct F { Q? a; Y? b; K? c; };  F? !f = new F;
+struct G { R? a; Z? b; L? c; };  G? !g = new G;
+struct H { S? a; A? b; M? c; };  H? !h = new H;
+struct I { T? a; B? b; N? c; };  I? !i = new I;
+struct J { U? a; C? b; O? c; };  J? !j = new J;
+struct K { V? a; D? b; P? c; };  K? !k = new K;
+struct L { W? a; E? b; Q? c; };  L? !l = new L;
+struct M { X? a; F? b; R? c; };  M? !m = new M;
+struct N { Y? a; G? b; S? c; };  N? !n = new N;
+struct O { Z? a; H? b; T? c; };  O? !o = new O;
+struct P { A? a; I? b; U? c; };  P? !p = new P;
+struct Q { B? a; J? b; V? c; };  Q? !q = new Q;
+struct R { C? a; K? b; W? c; };  R? !r = new R;
+struct S { D? a; L? b; X? c; };  S? !s = new S;
+struct T { E? a; M? b; Y? c; };  T? !t = new T;
+struct U { F? a; N? b; Z? c; };  U? !u = new U;
+struct V { G? a; O? b; A? c; };  V? !v = new V;
+struct W { H? a; P? b; B? c; };  W? !w = new W;
+struct X { I? a; Q? b; C? c; };  X? !x = new X;
+struct Y { J? a; R? b; D? c; };  Y? !y = new Y;
+struct Z { K? a; S? b; E? c; };  Z? !z = new Z;
+
+a.a=l;  a.b=t; a.c=f;
+b.a=m;  b.b=u; b.c=g;
+c.a=n;  c.b=v; c.c=h;
+d.a=o;  d.b=w; d.c=i;
+e.a=p;  e.b=x; e.c=j;
+f.a=q;  f.b=y; f.c=k;
+g.a=r;  g.b=z; g.c=l;
+h.a=s;  h.b=a; h.c=m;
+i.a=t;  i.b=b; i.c=n;
+j.a=u;  j.b=c; j.c=o;
+k.a=v;  k.b=d; k.c=p;
+l.a=w;  l.b=e; l.c=q;
+m.a=x;  m.b=f; m.c=r;
+n.a=y;  n.b=g; n.c=s;
+o.a=z;  o.b=h; o.c=t;
+p.a=a;  p.b=i; p.c=u;
+q.a=b;  q.b=j; q.c=v;
+r.a=c;  r.b=k; r.c=w;
+s.a=d;  s.b=l; s.c=x;
+t.a=e;  t.b=m; t.c=y;
+u.a=f;  u.b=n; u.c=z;
+v.a=g;  v.b=o; v.c=a;
+w.a=h;  w.b=p; w.c=b;
+x.a=i;  x.b=q; x.c=c;
+y.a=j;  y.b=r; y.c=d;
+z.a=k;  z.b=s; z.c=e;
+
+return a.b.c.a.b.c.a.b.c.a.b.c.a.b.c.a.b.c;
+
+""");
+        code.parse().opto().typeCheck().GCM().localSched();
+        assertEquals("return R;", code._stop.toString());
+        assertEquals("R{a=C{a=N{a=Y{a=J{a=U{a=F{a=Q{a=B{a=M{a=X{a=I{a=T{a=E{a=P{a=A{a=L{a=W{a=H{a=S{a=D{a=O{a=Z{a=K{a=V{a=G{a=$cyclic,b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic}", Eval2.eval(code,  0));
+    }
+
 }
diff --git a/src/test/java/com/seaofnodes/simple/Chapter14Test.java b/src/test/java/com/seaofnodes/simple/Chapter14Test.java
index 23c82358..a3025001 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter14Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter14Test.java
@@ -1,6 +1,5 @@
 package com.seaofnodes.simple;
 
-import com.seaofnodes.simple.evaluator.Evaluator;
 import com.seaofnodes.simple.node.StopNode;
 import org.junit.Test;
 
@@ -11,18 +10,18 @@ public class Chapter14Test {
 
     @Test
     public void testJig() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 return 3.14;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 3.14;", stop.toString());
-        assertEquals(3.14, Evaluator.evaluate(stop,  0));
+        code.parse().opto();
+        assertEquals("return 3.14;", code.print());
+        assertEquals("3.14", Eval2.eval(code,  0));
     }
 
     @Test
     public void testRange() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 int b;
 if( arg ) b=1; else b=0;
@@ -31,157 +30,157 @@ if( b < 0 ) c = -1;
 if( b > 2 ) c =  1;
 return c;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 99;", stop.toString());
-        assertEquals(99L, Evaluator.evaluate(stop,  0));
+        code.parse().opto();
+        assertEquals("return 99;", code.print());
+        assertEquals("99", Eval2.eval(code,  0));
     }
 
     @Test
     public void testU8() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 u8 b = 123;
 b = b + 456;// Truncate
 return b;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 67;", stop.toString());
-        assertEquals(67L, Evaluator.evaluate(stop,  0));
+        code.parse().opto();
+        assertEquals("return 67;", code.print());
+        assertEquals("67", Eval2.eval(code,  0));
     }
 
 
     @Test
     public void testU8While() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 u8 b = 123;
 while( b ) b = b + 456;// Truncate
 return b;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 0;", stop.toString());
+        code.parse().opto();
+        assertEquals("return 0;", code.print());
     }
 
     @Test
     public void testU1() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 bool b = 123;
 b = b + 456;// Truncate
 u1 c = b;   // No more truncate needed
 return c;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 1;", stop.toString());
-        assertEquals(1L, Evaluator.evaluate(stop,  0));
+        code.parse().opto();
+        assertEquals("return 1;", code.print());
+        assertEquals("1", Eval2.eval(code,  0));
     }
 
     @Test
     public void testAnd() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 int b = 123;
 b = b+456 & 31;                 // Precedence
 return b;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 3;", stop.toString());
-        assertEquals(3L, Evaluator.evaluate(stop,  0));
+        code.parse().opto();
+        assertEquals("return 3;", code.print());
+        assertEquals("3", Eval2.eval(code,  0));
     }
 
     @Test
     public void testRefLoad() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 struct Foo { u1 b; };
 Foo !f = new Foo;
 f.b = 123;
 return f.b;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 1;", stop.toString());
-        assertEquals(1L, Evaluator.evaluate(stop,  0));
+        code.parse().opto();
+        assertEquals("return 1;", code.print());
+        assertEquals("1", Eval2.eval(code,  0));
     }
 
     @Test
     public void testSigned() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 i8 b = 255;                     // Chopped
 return b;                       // Sign extend
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return -1;", stop.toString());
-        assertEquals(-1L, Evaluator.evaluate(stop,  0));
+        code.parse().opto();
+        assertEquals("return -1;", code.print());
+        assertEquals("-1", Eval2.eval(code,  0));
     }
 
     @Test
     public void testI8() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 i8 b = arg;
 b = b + 1;// Truncate
 return b;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return (((((arg<<56)>>56)+1)<<56)>>56);", stop.toString());
-        assertEquals(1L, Evaluator.evaluate(stop, 0));
-        assertEquals(-128L, Evaluator.evaluate(stop, 127));
+        code.parse().opto();
+        assertEquals("return (((((arg<<56)>>56)+1)<<56)>>56);", code.print());
+        assertEquals("1", Eval2.eval(code, 0));
+        assertEquals("-128", Eval2.eval(code, 127));
     }
 
     @Test
     public void testMask() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 u16 mask = (1<<16)-1;           // AND mask
 int c = 123456789 & mask;
 return c;                       //
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 52501;", stop.toString());
-        assertEquals(52501L, Evaluator.evaluate(stop,  0));
+        code.parse().opto();
+        assertEquals("return 52501;", code.print());
+        assertEquals("52501", Eval2.eval(code,  0));
     }
 
     @Test
     public void testOr() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 return (arg | 123 ^ 456) >>> 1;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return (((arg|123)^456)>>>1);", stop.toString());
-        assertEquals(217L, Evaluator.evaluate(stop,  0));
+        code.parse().opto();
+        assertEquals("return (((arg|123)^456)>>>1);", code.print());
+        assertEquals("217", Eval2.eval(code,  0));
     }
 
     @Test
     public void testMaskFloat() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 flt f = arg;
-arg = f & 0;
+arg = f & 1;
 return arg;
 """);
-        try { parser.parse().iterate(); fail(); }
-        catch( Exception e ) { assertEquals("Cannot '&' FltBot",e.getMessage()); }
+        try { code.parse().opto().typeCheck(); fail(); }
+        catch( Exception e ) { assertEquals("Cannot '&' flt",e.getMessage()); }
     }
 
     @Test
     public void testCloneAnd() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 int v0=0;
 u32 v1 = 1&(1<<arg)&(1<<arg);
 while(arg) v1=-v0;
 while(v1) break;
 return v1;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return (Phi(Loop,((1<<arg)&1),0)&Phi(Loop,Shl,4294967295));", stop.toString());
-        assertEquals(1L, Evaluator.evaluate(stop,  0));
+        code.parse().opto();
+        assertEquals("return (Phi(Loop,((1<<arg)&1),0)&Phi(Loop,Shl,4294967295));", code.print());
+        assertEquals("1", Eval2.eval(code,  0));
     }
 
     @Test
     public void testAndHigh() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 int v0=0;
 if(0&0>>>0) {
     while(0) {
@@ -193,14 +192,14 @@ if(0&0>>>0) {
 }
 return v0;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 0;", stop.toString());
-        assertEquals(0L, Evaluator.evaluate(stop,  0));
+        code.parse().opto();
+        assertEquals("return 0;", code.print());
+        assertEquals("0", Eval2.eval(code,  0));
     }
 
     @Test
     public void testTypes() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 i8  xi8  = 123456789;  if( xi8  !=        21 ) return -8;
 i16 xi16 = 123456789;  if( xi16 !=    -13035 ) return -16;
@@ -219,9 +218,9 @@ f32 ff32 = 3.141592653589793;  if( ff32 != 3.1415927410125732) return 5;
 
 return 0;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 0;", stop.toString());
-        assertEquals(0L, Evaluator.evaluate(stop,  0));
+        code.parse().opto();
+        assertEquals("return 0;", code.print());
+        assertEquals("0", Eval2.eval(code,  0));
     }
 
 }
diff --git a/src/test/java/com/seaofnodes/simple/Chapter15Test.java b/src/test/java/com/seaofnodes/simple/Chapter15Test.java
index 4e2682dc..86f5007d 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter15Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter15Test.java
@@ -1,42 +1,38 @@
 package com.seaofnodes.simple;
 
-import com.seaofnodes.simple.evaluator.Evaluator;
-import com.seaofnodes.simple.node.StopNode;
 import org.junit.Test;
-import org.junit.Ignore;
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.fail;
+import static org.junit.Assert.*;
 
 public class Chapter15Test {
 
     @Test
     public void testJig() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 return 3.14;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 3.14;", stop.toString());
-        assertEquals(3.14, Evaluator.evaluate(stop,  0));
+        code.parse().opto();
+        assertEquals("return 3.14;", code.print());
+        assertEquals("3.14", Eval2.eval(code,  0));
     }
 
     @Test
     public void testCyclic() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 struct C { C? l; };
 C !c = new C;
 c.l = c;
 return c;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return C;", stop.toString());
-        assertEquals("Obj<C>@1{l=obj@1}", Evaluator.evaluate(stop,  0).toString());
+        code.parse().opto();
+        assertEquals("return C;", code.print());
+        assertEquals("C{l=$cyclic}", Eval2.eval(code,  0));
     }
 
     @Test
     public void testSafetyCheck() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 u8[] old = new u8[0];
 u8[] !output = new u8[1];
@@ -48,66 +44,66 @@ while (i < old#) {
 output[i] = 1;
 return output;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return [u8];", stop.toString());
-        assertEquals("\u0001", Evaluator.evaluate(stop,  0).toString());
+        code.parse().opto();
+        assertEquals("return [u8];", code.print());
+        assertEquals("\u0001", Eval2.eval(code,  0));
     }
 
     @Test
     public void testBasic1() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 int[] is = new int[2];
 return is[1];
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 0;", stop.toString());
-        assertEquals(0L, Evaluator.evaluate(stop,  0));
+        code.parse().opto();
+        assertEquals("return 0;", code.print());
+        assertEquals("0", Eval2.eval(code,  0));
     }
 
     @Test
     public void testBasic2() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 int[] is = new int[2];
 int[] is2 = new int[2];
 return is[1];
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 0;", stop.toString());
-        assertEquals(0L, Evaluator.evaluate(stop,  0));
+        code.parse().opto();
+        assertEquals("return 0;", code.print());
+        assertEquals("0", Eval2.eval(code,  0));
     }
 
     @Test
     public void testBasic3() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 int[] !a = new int[2];
 a[0] = 1;
 a[1] = 2;
 return a[0];
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 1;", stop.toString());
-        assertEquals(1L, Evaluator.evaluate(stop,  0));
+        code.parse().opto();
+        assertEquals("return 1;", code.print());
+        assertEquals("1", Eval2.eval(code,  0));
     }
 
     @Test
     public void testBasic4() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 struct A { int i; };
 A?[] !a = new A?[2];
 return a;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return [*A?];", stop.toString());
-        assertEquals("Obj<[*A?]>{#=2,[]=[null,null]}", Evaluator.evaluate(stop, 0).toString());
+        code.parse().opto();
+        assertEquals("return [*A?];", code.print());
+        assertEquals("*A {int !i; }?[ null,null]", Eval2.eval(code, 0));
     }
 
     @Test
     public void testBasic5() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 struct S { int x; flt y; };
 // A new S
@@ -129,15 +125,15 @@ else {
 }
 return rez;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Region,1.2,Phi(Region,2.3,3.14));", stop.toString());
-        assertEquals(3.14, Evaluator.evaluate(stop, 0));
-        assertEquals(1.2 , Evaluator.evaluate(stop, 1));
+        code.parse().opto();
+        assertEquals("return Phi(Region,1.2,Phi(Region,2.3,.y));", code.print());
+        assertEquals("3.14", Eval2.eval(code, 0));
+        assertEquals("1.2", Eval2.eval(code, 1));
     }
 
     @Test
     public void testBasic6() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 struct S { int x; flt y; };
 // A new S
@@ -155,13 +151,13 @@ if( iss[arg] )
         rez = iss[arg][2].y;
 return rez;
 """);
-        try { parser.parse().iterate(); fail(); }
+        try { code.parse().opto().typeCheck(); fail(); }
         catch( Exception e ) { assertEquals("Might be null accessing 'y'",e.getMessage()); }
     }
 
     @Test
     public void testTree() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 // Can we define a forward-reference array?
 struct Tree { Tree?[]? _kids; };
@@ -170,25 +166,25 @@ root._kids = new Tree?[2]; // NO BANG SO ARRAY IS OF IMMUTABLE TREES????
 root._kids[0] = new Tree;
 return root;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Tree;", stop.toString());
-        assertEquals("Obj<Tree>{_kids=Obj<[*Tree?]>{#=2,[]=[Obj<Tree>{_kids=null},null]}}", Evaluator.evaluate(stop,  0).toString());
+        code.parse().opto();
+        assertEquals("return Tree;", code.print());
+        assertEquals("Tree{_kids=*Tree?[ Tree{_kids=null},null]}", Eval2.eval(code,  0));
     }
 
     @Test
     public void testNestedStructAddMemProj() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 struct S { int a; int[] b; };
 return 0;
 """);
-        StopNode stop = parser.parse();
-        assertEquals("return 0;", stop.toString());
+        code.parse().opto();
+        assertEquals("return 0;", code.print());
     }
 
     @Test
     public void testRollingSum() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 int[] !ary = new int[arg];
 // Fill [0,1,2,3,4,...]
@@ -205,14 +201,14 @@ while( i < ary# - 1 ) {
 }
 return ary[1] * 1000 + ary[3]; // 1 * 1000 + 6
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return (.[]+(.[]*1000));", stop.toString());
-        assertEquals(1006L, Evaluator.evaluate(stop,  4));
+        code.parse().opto();
+        assertEquals("return (.[]+(.[]*1000));", code.print());
+        assertEquals("1006", Eval2.eval(code,  4));
     }
 
     @Test
     public void sieveOEratosthenes() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 int[] !ary = new int[arg], !primes = new int[arg];
 int nprimes = 0, p=2;
@@ -246,19 +242,14 @@ while( j < nprimes ) {
 }
 return rez;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return [int];", stop.toString());
-        Evaluator.Obj obj = (Evaluator.Obj)Evaluator.evaluate(stop, 20);
-        assertEquals("[int] {int #; int ![]; }",obj.struct().toString());
-        long nprimes = (Long)obj.fields()[0];
-        long[] primes = new long[]{2,3,5,7,11,13,17,19};
-        for( int i=0; i<nprimes; i++ )
-            assertEquals(primes[i],(long)(Long)obj.fields()[i+1]);
+        code.parse().opto();
+        assertEquals("return [int];", code.print());
+        assertEquals("int[ 2,3,5,7,11,13,17,19]",Eval2.eval(code, 20));
     }
 
     @Test
     public void testNewNodeInit() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 struct S {int i; flt f;};
 S !s1 = new S;
@@ -268,62 +259,62 @@ s2.f = 2.0;
 if (arg) s1 = new S;
 return s1.i + s1.f;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return ((flt).i+.f);", stop.toString());
-        assertEquals(0.0, Evaluator.evaluate(stop,  0));
+        code.parse().opto();
+        assertEquals("return ((flt).i+.f);", code.print());
+        assertEquals("0.0", Eval2.eval(code,  0));
     }
 
 
     @Test
     public void testBad0() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 return new flt;
 """);
-        try { parser.parse().iterate(); fail(); }
+        try { code.parse().opto(); fail(); }
         catch( Exception e ) { assertEquals("Cannot allocate a flt",e.getMessage()); }
     }
 
     @Test
     public void testBad1() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 int is = new int[2];
 """);
-        try { parser.parse().iterate(); fail(); }
+        try { code.parse().opto(); fail(); }
         catch( Exception e ) { assertEquals("Type *[int] is not of declared type int",e.getMessage()); }
     }
 
     @Test
     public void testBad2() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 int[] is = new int[3.14];
 return is[1];
 """);
-        try { parser.parse().iterate(); fail(); }
+        try { code.parse().opto(); fail(); }
         catch( Exception e ) { assertEquals("Cannot allocate an array with length 3.14",e.getMessage()); }
     }
 
     @Test
     public void testBad3() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 int[] is = new int[arg];
 return is[1];
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 0;", stop.toString());
-        assertEquals(0L, Evaluator.evaluate(stop,  4));
-        try { Evaluator.evaluate(stop,0); }
+        code.parse().opto();
+        assertEquals("return 0;", code.print());
+        assertEquals("0", Eval2.eval(code,  4));
+        try { Eval2.eval(code,0); }
         catch( ArrayIndexOutOfBoundsException e ) { assertEquals("Array index 1 out of bounds for array length 0",e.getMessage()); }
-        try { Evaluator.evaluate(stop,-1); }
+        try { Eval2.eval(code,-1); }
         catch( NegativeArraySizeException e ) { assertEquals("-1",e.getMessage()); }
     }
 
     @Test
     public void testProgress() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 i8 v1=0&0;
 u8 v2=0;
 byte v4=0;
@@ -342,14 +333,14 @@ while(v5+(0&0)) {
 }
 return v1;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 0;", stop.toString());
-        assertEquals(0L, Evaluator.evaluate(stop,  0));
+        code.parse().opto();
+        assertEquals("return 0;", code.print());
+        assertEquals("0", Eval2.eval(code,  0));
     }
 
     @Test
     public void testSharpNot() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 if(0>>0) {}
 while(0) {}
@@ -357,14 +348,14 @@ u32 v7=0;
 int v8=0;
 while(0<--1>>>---(v7*0==v8)) {}
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 0;", stop.toString());
+        code.parse().opto();
+        assertEquals("return 0;", code.print());
     }
 
 
     @Test
     public void testProgress2() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 if(1) {}
 else {
@@ -381,7 +372,7 @@ else {
         }
 }
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 0;", stop.toString());
+        code.parse().opto();
+        assertEquals("return 0;", code.print());
     }
 }
diff --git a/src/test/java/com/seaofnodes/simple/Chapter16Test.java b/src/test/java/com/seaofnodes/simple/Chapter16Test.java
index 5450824a..ad3dc690 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter16Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter16Test.java
@@ -10,180 +10,180 @@ public class Chapter16Test {
 
     @Test
     public void testJig() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 return 3.14;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 3.14;", stop.toString());
-        assertEquals(3.14, Evaluator.evaluate(stop,  0));
+        code.parse().opto();
+        assertEquals("return 3.14;", code.print());
+        assertEquals("3.14", Eval2.eval(code,  0));
     }
 
 
     @Test
     public void testMulti0() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 int x, y;
 return x+y;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 0;", stop.toString());
-        assertEquals(0L, Evaluator.evaluate(stop,  0));
+        code.parse().opto();
+        assertEquals("return 0;", code.print());
+        assertEquals("0", Eval2.eval(code,  0));
     }
     @Test
     public void testMulti1() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 int x=2, y=x+1;
 return x+y;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 5;", stop.toString());
-        assertEquals(5L, Evaluator.evaluate(stop,  0));
+        code.parse().opto();
+        assertEquals("return 5;", code.print());
+        assertEquals("5", Eval2.eval(code,  0));
     }
 
 //    @Test
 //    public void testFinal0() {
-//        Parser parser = new Parser(
+//        CodeGen code = new CodeGen(
 //"""
 //int !x=2;
 //x=3;
 //return x;
 //""");
-//        try { parser.parse().iterate(); fail(); }
+//        try { code.parse().opto(); fail(); }
 //        catch( Exception e ) { assertEquals("Cannot reassign final 'x'",e.getMessage()); }
 //    }
 
     @Test
     public void testFinal1() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 int x=2, y=3;
 if( arg ) { int x = y; x = x*x; y=x; } // Shadow final x
 return y;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Region,9,3);", stop.toString());
-        assertEquals(3L, Evaluator.evaluate(stop, 0));
-        assertEquals(9L, Evaluator.evaluate(stop, 1));
+        code.parse().opto();
+        assertEquals("return Phi(Region,9,3);", code.print());
+        assertEquals("3", Eval2.eval(code, 0));
+        assertEquals("9", Eval2.eval(code, 1));
     }
 
     @Test
     public void testConstruct0() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 struct X { int x=3; };
 X z = new X;
 return z.x;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 3;", stop.toString());
-        assertEquals(3L, Evaluator.evaluate(stop,  0));
+        code.parse().opto();
+        assertEquals("return 3;", code.print());
+        assertEquals("3", Eval2.eval(code,  0));
     }
 
     @Test
     public void testConstruct1() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 struct X { int !x; };
 X z = new X { x=3; };
 return z.x;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 3;", stop.toString());
-        assertEquals(3L, Evaluator.evaluate(stop,  0));
+        code.parse().opto();
+        assertEquals("return 3;", code.print());
+        assertEquals("3", Eval2.eval(code,  0));
     }
 
     @Test
     public void testConstruct2() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 struct X { int x=3; };
 X z = new X { x = 4; };
 return z.x;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 4;", stop.toString());
-        assertEquals(4L, Evaluator.evaluate(stop,  0));
+        code.parse().opto();
+        assertEquals("return 4;", code.print());
+        assertEquals("4", Eval2.eval(code,  0));
     }
 
 
     @Test
     public void testStructFinal0() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 struct Point { int !x, !y; };
 Point p = new Point { x=3; y=4; };
 return p;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return (const)Point;", stop.toString());
-        assertEquals("Obj<Point>{x=3,y=4}", Evaluator.evaluate(stop,  0).toString());
+        code.parse().opto();
+        assertEquals("return (const)Point;", code.print());
+        assertEquals("Point{x=3,y=4}", Eval2.eval(code,  0));
     }
 
     @Test
     public void testStructFinal1() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 struct Point { int x=3, y=4; };
 Point p = new Point { x=5; y=6; };
 p.x++;
 return p;
 """);
-        try { parser.parse().iterate(); fail(); }
+        try { code.parse().opto().typeCheck(); fail(); }
         catch( Exception e ) { assertEquals("Cannot modify final field 'x'",e.getMessage()); }
     }
 
     @Test
     public void testStructFinal2() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 struct Point { int x=3, y=4; };
 Point p = new Point;
 p.x++;
 return p;
 """);
-        try { parser.parse().iterate(); fail(); }
+        try { code.parse().opto().typeCheck(); fail(); }
         catch( Exception e ) { assertEquals("Cannot modify final field 'x'",e.getMessage()); }
     }
 
     @Test
     public void testStructFinal3() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 struct Point { var x; var y; };
 Point p = new Point;
 p.x++;
 return p;
 """);
-        try { parser.parse().iterate(); fail(); }
+        try { code.parse().opto(); fail(); }
         catch( Exception e ) { assertEquals("'Point' is not fully initialized, field 'x' needs to be set in a constructor",e.getMessage()); }
     }
 
     @Test
     public void testStructFinal4() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 struct Point { val x=3; val y=4; };
 Point p = new Point;
 p.x++;
 return p;
 """);
-        try { parser.parse().iterate(); fail(); }
+        try { code.parse().opto(); fail(); }
         catch( Exception e ) { assertEquals("Cannot reassign final 'x'",e.getMessage()); }
     }
 
     @Test
     public void testStructFinal5() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 struct Point { var x=3; var y=4; };
 Point !p = new Point;
 p.x++;
 return p;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Point;", stop.toString());
-        assertEquals("Obj<Point>{x=4,y=4}", Evaluator.evaluate(stop,  0).toString());
+        code.parse().opto();
+        assertEquals("return Point;", code.print());
+        assertEquals("Point{x=4,y=4}", Eval2.eval(code,  0));
     }
 
     // Same as the Chapter13 test with the same name, but using the new
     // constructor syntax
     @Test
     public void testLinkedList1() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 struct LLI { LLI? next; int i; };
 LLI? !head = null;
@@ -196,16 +196,16 @@ LLI? next = head.next;
 if( !next ) return 1;
 return next.i;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("Stop[ return 0; return 1; return .i; ]", stop.toString());
-        assertEquals(0L, Evaluator.evaluate(stop,  0));
-        assertEquals(1L, Evaluator.evaluate(stop,  1));
-        assertEquals(2L, Evaluator.evaluate(stop,  3));
+        code.parse().opto();
+        assertEquals("return Phi(Region,0,1,.i);", code.print());
+        assertEquals("0", Eval2.eval(code,  0));
+        assertEquals("1", Eval2.eval(code,  1));
+        assertEquals("2", Eval2.eval(code,  3));
     }
 
     @Test
     public void testLinkedList2() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 struct LLI { LLI? next; int i; };
 LLI? !head = null;
@@ -227,16 +227,16 @@ LLI? next = head.next;
 if( !next ) return 1;
 return next.i;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("Stop[ return 0; return 1; return .i; ]", stop.toString());
-        assertEquals(0L, Evaluator.evaluate(stop,  0));
-        assertEquals(1L, Evaluator.evaluate(stop,  1));
-        assertEquals(2L, Evaluator.evaluate(stop, 11));
+        code.parse().opto();
+        assertEquals("return Phi(Region,0,1,.i);", code.print());
+        assertEquals("0", Eval2.eval(code,  0));
+        assertEquals("1", Eval2.eval(code,  1));
+        assertEquals("2", Eval2.eval(code, 11));
     }
 
     @Test
     public void testSquare() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 struct Square {
     flt !side = arg;
@@ -252,9 +252,9 @@ struct Square {
 };
 return new Square;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Square;", stop.toString());
-        assertEquals("Obj<Square>{side=3.0,diag=1.7320508075688772}", Evaluator.evaluate(stop,  3).toString());
-        assertEquals("Obj<Square>{side=4.0,diag=2.0}", Evaluator.evaluate(stop, 4).toString());
+        code.parse().opto();
+        assertEquals("return Square;", code.print());
+        assertEquals("Square{side=3.0,diag=1.7320508075688772}", Eval2.eval(code,  3));
+        assertEquals("Square{side=4.0,diag=2.0}", Eval2.eval(code, 4));
     }
 }
diff --git a/src/test/java/com/seaofnodes/simple/Chapter17Test.java b/src/test/java/com/seaofnodes/simple/Chapter17Test.java
index 4a7e959a..8ec95f33 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter17Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter17Test.java
@@ -1,9 +1,6 @@
 package com.seaofnodes.simple;
 
-import com.seaofnodes.simple.evaluator.Evaluator;
-import com.seaofnodes.simple.node.StopNode;
 import org.junit.Test;
-import org.junit.Ignore;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.fail;
 
@@ -11,187 +8,202 @@ public class Chapter17Test {
 
     @Test
     public void testJig() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen(
+"""
 int i = 0;
 i=i=1;
 return i;
-                                   //return 3.14;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 1;", stop.toString());
-        assertEquals(1L, Evaluator.evaluate(stop,  0));
+        code.parse().opto();
+        assertEquals("return 1;", code.print());
+        assertEquals("1", Eval2.eval(code,  0));
     }
 
 
     // ---------------------------------------------------------------
     @Test
     public void testInc0() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 return arg++;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return arg;", stop.toString());
-        assertEquals(0L, Evaluator.evaluate(stop, 0));
+        code.parse().opto();
+        assertEquals("return arg;", code.print());
+        assertEquals("0", Eval2.eval(code, 0));
     }
 
     @Test
     public void testInc1() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 return arg+++arg++;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return ((arg*2)+1);", stop.toString());
-        assertEquals(1L, Evaluator.evaluate(stop, 0));
+        code.parse().opto();
+        assertEquals("return ((arg*2)+1);", code.print());
+        assertEquals("1", Eval2.eval(code, 0));
     }
 
     @Test
     public void testInc2() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 //   -(arg--)-(arg--)
 return -arg---arg--;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return (-((arg*2)+-1));", stop.toString());
-        assertEquals(1L, Evaluator.evaluate(stop, 0));
+        code.parse().opto();
+        assertEquals("return (-((arg*2)+-1));", code.print());
+        assertEquals("1", Eval2.eval(code, 0));
     }
 
     @Test
     public void testInc3() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 int[] !xs = new int[arg];
 xs[0]++;
 xs[1]++;
 return xs[0];
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 1;", stop.toString());
-        assertEquals(1L, Evaluator.evaluate(stop, 2));
+        code.parse().opto();
+        assertEquals("return 1;", code.print());
+        assertEquals("1", Eval2.eval(code, 2));
     }
 
     @Test
     public void testInc4() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 u8[] !xs = new u8[1];
 xs[0]--;
 return xs[0];
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 255;", stop.toString());
-        assertEquals(255L, Evaluator.evaluate(stop, 2));
+        code.parse().opto();
+        assertEquals("return 255;", code.print());
+        assertEquals("255", Eval2.eval(code, 2));
     }
 
     @Test
     public void testInc5() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 struct S { u16 x; };
 S !s = new S;
 s.x--;
 return s.x;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 65535;", stop.toString());
-        assertEquals(65535L, Evaluator.evaluate(stop, 2));
+        code.parse().opto();
+        assertEquals("return 65535;", code.print());
+        assertEquals("65535", Eval2.eval(code, 2));
     }
 
     @Test
     public void testInc6() {
-        Parser parser = new Parser("return --arg;");
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return (arg+-1);", stop.toString());
-        assertEquals(-1L, Evaluator.evaluate(stop, 0));
+        CodeGen code = new CodeGen("return --arg;");
+        code.parse().opto();
+        assertEquals("return (arg+-1);", code.print());
+        assertEquals("-1", Eval2.eval(code, 0));
     }
 
     @Test
     public void testInc7() {
-        Parser parser = new Parser("u8 x=0; return --x;");
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 255;", stop.toString());
-        assertEquals(255L, Evaluator.evaluate(stop, 0));
+        CodeGen code = new CodeGen("u8 x=0; return --x;");
+        code.parse().opto();
+        assertEquals("return 255;", code.print());
+        assertEquals("255", Eval2.eval(code, 0));
     }
 
     @Test
     public void testInc8() {
-        Parser parser = new Parser("int x; x+=2; return x+=3;");
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 5;", stop.toString());
-        assertEquals(5L, Evaluator.evaluate(stop, 0));
+        CodeGen code = new CodeGen("int x; x+=2; return x+=3;");
+        code.parse().opto();
+        assertEquals("return 5;", code.print());
+        assertEquals("5", Eval2.eval(code, 0));
+    }
+
+    @Test
+    public void testInc9() {
+        CodeGen code = new CodeGen("flt x = 1.5; x++; return x;");
+        code.parse().opto();
+        assertEquals("return 2.5f;", code.print());
+        assertEquals("2.5", Eval2.eval(code, 0));
     }
 
+    @Test public void testInt10() {
+        CodeGen code = new CodeGen("flt x = 1.5; x++; int i = x; return i;");
+        try { code.parse().opto(); fail(); }
+        catch( Exception e ) { assertEquals("Type 2.5f is not of declared type int",e.getMessage()); }
+    }
+
+
     // ---------------------------------------------------------------
     @Test public void testVar0() {
-        Parser parser = new Parser("var d; return d;");
-        try { parser.parse().iterate(); fail(); }
+        CodeGen code = new CodeGen("var d; return d;");
+        try { code.parse().opto(); fail(); }
         catch( Exception e ) { assertEquals("Syntax error, expected =expression: ;",e.getMessage()); }
     }
 
     @Test public void testVar1() {
-        Parser parser = new Parser("val d; return d;");
-        try { parser.parse().iterate(); fail(); }
+        CodeGen code = new CodeGen("val d; return d;");
+        try { code.parse().opto(); fail(); }
         catch( Exception e ) { assertEquals("Syntax error, expected =expression: ;",e.getMessage()); }
     }
 
     @Test public void testVar2() {
-        Parser parser = new Parser("int x; x=3; x++; return x; // Ok, no initializer so x is mutable ");
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 4;", stop.toString());
-        assertEquals(4L, Evaluator.evaluate(stop, 0));
+        CodeGen code = new CodeGen("int x; x=3; x++; return x; // Ok, no initializer so x is mutable ");
+        code.parse().opto();
+        assertEquals("return 4;", code.print());
+        assertEquals("4", Eval2.eval(code, 0));
     }
 
     @Test public void testVar3() {
-        Parser parser = new Parser("int x=3; x++; return x; // Ok, primitive so x is mutable despite initializer ");
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 4;", stop.toString());
-        assertEquals(4L, Evaluator.evaluate(stop, 0));
+        CodeGen code = new CodeGen("int x=3; x++; return x; // Ok, primitive so x is mutable despite initializer ");
+        code.parse().opto();
+        assertEquals("return 4;", code.print());
+        assertEquals("4", Eval2.eval(code, 0));
     }
 
     @Test public void testVar4() {
-        Parser parser = new Parser("struct S{int x;}; S s; s=new S; s.x++; return s.x; // Ok, no initializer so x is mutable ");
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 1;", stop.toString());
-        assertEquals(1L, Evaluator.evaluate(stop, 0));
+        CodeGen code = new CodeGen("struct S{int x;}; S? s; s=new S; s.x++; return s.x; // Ok, no initializer so x is mutable ");
+        code.parse().opto();
+        assertEquals("return 1;", code.print());
+        assertEquals("1", Eval2.eval(code, 0));
     }
 
     @Test public void testVar5() {
-        Parser parser = new Parser("struct S{int x;}; S s; s=new S{x=3;}; s.x++; return s.x; // Ok, no initializer so x is mutable ");
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 4;", stop.toString());
-        assertEquals(4L, Evaluator.evaluate(stop, 0));
+        CodeGen code = new CodeGen("struct S{int x;}; S? s; s=new S{x=3;}; s.x++; return s.x; // Ok, no initializer so x is mutable ");
+        code.parse().opto();
+        assertEquals("return 4;", code.print());
+        assertEquals("4", Eval2.eval(code, 0));
     }
 
     @Test public void testVar6() {
-        Parser parser = new Parser("struct S{int x;}; S s=new S; s.x++; return s.x; // Error initializer so x is immutable ");
-        try { parser.parse().iterate(); fail(); }
+        CodeGen code = new CodeGen("struct S{int x;}; S s=new S; s.x++; return s.x; // Error initializer so x is immutable ");
+        try { code.parse().opto().typeCheck(); fail(); }
         catch( Exception e ) { assertEquals("Cannot modify final field 'x'",e.getMessage()); }
     }
 
     @Test public void testVar7() {
-        Parser parser = new Parser("struct S{int x;}; S s=new S{x=3;}; s.x++; return s.x; // Error initializer so x is immutable ");
-        try { parser.parse().iterate(); fail(); }
+        CodeGen code = new CodeGen("struct S{int x;}; S s=new S{x=3;}; s.x++; return s.x; // Error initializer so x is immutable ");
+        try { code.parse().opto().typeCheck(); fail(); }
         catch( Exception e ) { assertEquals("Cannot modify final field 'x'",e.getMessage()); }
     }
 
     @Test public void testVar8() {
-        Parser parser = new Parser("struct S{int x;}; S !s=new S; s.x++; return s.x; // Ok, has '!' so s.x is mutable ");
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 1;", stop.toString());
-        assertEquals(1L, Evaluator.evaluate(stop, 0));
+        CodeGen code = new CodeGen("struct S{int x;}; S !s=new S; s.x++; return s.x; // Ok, has '!' so s.x is mutable ");
+        code.parse().opto();
+        assertEquals("return 1;", code.print());
+        assertEquals("1", Eval2.eval(code, 0));
     }
 
     @Test public void testVar9() {
-        Parser parser = new Parser("struct S{int x;}; var s=new S; s.x++; return s.x; // Ok, has var so s.x is mutable ");
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 1;", stop.toString());
-        assertEquals(1L, Evaluator.evaluate(stop, 0));
+        CodeGen code = new CodeGen("struct S{int x;}; var s=new S; s.x++; return s.x; // Ok, has var so s.x is mutable ");
+        code.parse().opto();
+        assertEquals("return 1;", code.print());
+        assertEquals("1", Eval2.eval(code, 0));
     }
 
     @Test public void testVar10() {
-        Parser parser = new Parser("struct S{int x;}; val s=new S; s.x++; return s.x; // Error, has val so x is immutable ");
-        try { parser.parse().iterate(); fail(); }
+        CodeGen code = new CodeGen("struct S{int x;}; val s=new S; s.x++; return s.x; // Error, has val so x is immutable ");
+        try { code.parse().opto().typeCheck(); fail(); }
         catch( Exception e ) { assertEquals("Cannot modify final field 'x'",e.getMessage()); }
     }
 
     @Test public void testVar11() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 struct Bar { int x; };
 Bar !bar = new Bar;
 bar.x = 3; // Ok, bar is mutable
@@ -204,12 +216,12 @@ foo.bar.x++;   // Ok foo and foo.bar and foo.bar.x are all mutable
 val xfoo = foo; // Throw away mutability
 xfoo.bar.x++;   // Error, cannot mutate through xfoo
  """);
-        try { parser.parse().iterate(); fail(); }
+        try { code.parse().opto().typeCheck(); fail(); }
         catch( Exception e ) { assertEquals("Cannot modify final field 'x'",e.getMessage()); }
     }
 
     @Test public void testVar12() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 struct Bar { int x; };
 Bar !bar = new Bar;
 bar.x = 3; // Ok, bar is mutable
@@ -225,24 +237,24 @@ foo.bar.x++;           // Bumps to 5
 int x5 = xfoo.bar.x;   // Ok to read through xfoo, gets 5
 return x4*10+x5;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 45;", stop.toString());
-        assertEquals(45L, Evaluator.evaluate(stop, 0));
+        code.parse().opto();
+        assertEquals("return 45;", code.print());
+        assertEquals("45", Eval2.eval(code, 0));
     }
 
     @Test
     public void testVar13() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 int i,i++;
 """);
-        try { parser.parse().iterate(); fail(); }
+        try { code.parse().opto().typeCheck(); fail(); }
         catch( Exception e ) { assertEquals("Redefining name 'i'",e.getMessage()); }
     }
 
 
     @Test
     public void testVar14() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 struct B {};
 struct A { B b; };
 A x = new A {
@@ -250,127 +262,171 @@ A x = new A {
     b = new B;
 };
 """);
-        try { parser.parse().iterate(); fail(); }
+        try { code.parse().opto(); fail(); }
         catch( Exception e ) { assertEquals("Cannot read uninitialized field 'b'",e.getMessage()); }
     }
 
     @Test
     public void testVar15() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 struct B {};
 struct A { B b; };
 return new A {
     if (arg) b = new B; // Constructor ends with partial init of b
 }.b;
 """);
-        try { parser.parse().iterate(); fail(); }
+        try { code.parse().opto(); fail(); }
         catch( Exception e ) { assertEquals("'A' is not fully initialized, field 'b' needs to be set in a constructor",e.getMessage()); }
     }
 
+    @Test
+    public void testVar16() {
+        CodeGen code = new CodeGen(
+"""
+struct S{};
+val x = 1;
+val s = new S{x = 2;};
+return x;
+"""
+);
+        try { code.parse().opto().typeCheck(); fail(); }
+        catch( Exception e ) { assertEquals("Cannot reassign final 'x'",e.getMessage()); }
+    }
+
+    @Test
+    public void testVar17() {
+        CodeGen code = new CodeGen(
+"""
+struct Person {
+    bool focused;
+};
+val focus = { Person p ->
+    p.focused = true;
+};
+Person me; // Person !me = new Person;
+focus(me);
+return me;
+"""
+);
+        try { code.parse().opto().typeCheck(); fail(); }
+        catch( Exception e ) { assertEquals("Syntax error, expected =expression: ;",e.getMessage()); }
+    }
+
     // ---------------------------------------------------------------
     @Test
     public void testTrinary0() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 return arg ? 1 : 2;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Region,1,2);", stop.toString());
-        assertEquals(2L, Evaluator.evaluate(stop, 0));
-        assertEquals(1L, Evaluator.evaluate(stop, 1));
+        code.parse().opto();
+        assertEquals("return Phi(Region,1,2);", code.print());
+        assertEquals("2", Eval2.eval(code, 0));
+        assertEquals("1", Eval2.eval(code, 1));
     }
 
     @Test
     public void testTrinary1() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 return arg ? 0 : arg;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return 0;", stop.toString());
-        assertEquals(0L, Evaluator.evaluate(stop, 0));
+        code.parse().opto();
+        assertEquals("return 0;", code.print());
+        assertEquals("0", Eval2.eval(code, 0));
     }
 
     @Test
     public void testTrinary2() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 struct Bar { int x; };
 var b = arg ? new Bar : null;
 return b ? b.x++ + b.x++ : -1;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Region,1,-1);", stop.toString());
-        assertEquals(-1L, Evaluator.evaluate(stop, 0));
-        assertEquals( 1L, Evaluator.evaluate(stop, 1));
+        code.parse().opto();
+        assertEquals("return Phi(Region,((.x*2)+1),-1);", code.print());
+        assertEquals("-1", Eval2.eval(code, 0));
+        assertEquals("1", Eval2.eval(code, 1));
     }
 
     @Test
     public void testTrinary3() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 struct Bar { int x; };
 var b = arg ? new Bar;
 return b ? b.x++ + b.x++ : -1;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Region,1,-1);", stop.toString());
-        assertEquals(-1L, Evaluator.evaluate(stop, 0));
-        assertEquals( 1L, Evaluator.evaluate(stop, 1));
+        code.parse().opto();
+        assertEquals("return Phi(Region,((.x*2)+1),-1);", code.print());
+        assertEquals("-1", Eval2.eval(code, 0));
+        assertEquals("1", Eval2.eval(code, 1));
     }
 
     @Test
     public void testTrinary4() {
         // This test case will benefit from an unzipping transformation
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 struct Bar { Bar? next; int x; };
 var b = arg ? new Bar { next = (arg==2) ? new Bar{x=2;}; x=1; };
 return b ? b.next ? b.next.x : b.x; // parses "b ? (b.next ? b.next.x : b.x) : 0"
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Region,Phi(Region,.x,.x),0);", stop.toString());
-        assertEquals( 0L, Evaluator.evaluate(stop, 0));
-        assertEquals( 1L, Evaluator.evaluate(stop, 1));
-        assertEquals( 2L, Evaluator.evaluate(stop, 2));
+        code.parse().opto();
+        assertEquals("return Phi(Region,Phi(Region,.x,.x),0);", code.print());
+        assertEquals("0", Eval2.eval(code, 0));
+        assertEquals("1", Eval2.eval(code, 1));
+        assertEquals("2", Eval2.eval(code, 2));
     }
 
     @Test
     public void testTrinary5() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 flt f=arg?1:1.2;
 return f;   // missing widening
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Region,1.0,1.2);", stop.toString());
-        assertEquals(1.2, Evaluator.evaluate(stop,  0));
+        code.parse().opto();
+        assertEquals("return Phi(Region,1.0f,1.2);", code.print());
+        assertEquals("1.2", Eval2.eval(code,  0));
+    }
+
+
+    @Test
+    public void testTrinary6() {
+        CodeGen code = new CodeGen("""
+struct S{};
+return arg ? 7 : new S;
+""");
+        try { code.parse().opto().typeCheck(); fail(); }
+        catch( Exception e ) { assertEquals("No common type amongst int and reference",e.getMessage()); }
     }
 
     // ---------------------------------------------------------------
     @Test
     public void testFor0() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 int sum=0;
 for( int i=0; i<arg; i++ )
     sum += i;
 return sum;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Loop,0,(Phi_sum+Phi(Loop,0,(Phi_i+1))));", stop.toString());
-        assertEquals(3L, Evaluator.evaluate(stop, 3));
-        assertEquals(45L, Evaluator.evaluate(stop, 10));
+        code.parse().opto();
+        assertEquals("return Phi(Loop,0,(Phi_sum+Phi(Loop,0,(Phi_i+1))));", code.print());
+        assertEquals("3", Eval2.eval(code, 3));
+        assertEquals("45", Eval2.eval(code, 10));
     }
     @Test
     public void testFor1() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 int sum=0, i=0;
 for( ; i<arg; i++ )
     sum += i;
 return sum;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Loop,0,(Phi_sum+Phi(Loop,0,(Phi_i+1))));", stop.toString());
-        assertEquals(3L, Evaluator.evaluate(stop, 3));
-        assertEquals(45L, Evaluator.evaluate(stop, 10));
+        code.parse().opto();
+        assertEquals("return Phi(Loop,0,(Phi_sum+Phi(Loop,0,(Phi_i+1))));", code.print());
+        assertEquals("3", Eval2.eval(code, 3));
+        assertEquals("45", Eval2.eval(code, 10));
     }
     @Test
     public void testFor2() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 int sum=0;
 for( int i=0; ; i++ ) {
     if( i>=arg ) break;
@@ -378,41 +434,41 @@ for( int i=0; ; i++ ) {
 }
 return sum;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Loop,0,(Phi_sum+Phi(Loop,0,(Phi_i+1))));", stop.toString());
-        assertEquals(3L, Evaluator.evaluate(stop, 3));
-        assertEquals(45L, Evaluator.evaluate(stop, 10));
+        code.parse().opto();
+        assertEquals("return Phi(Loop,0,(Phi_sum+Phi(Loop,0,(Phi_i+1))));", code.print());
+        assertEquals("3", Eval2.eval(code, 3));
+        assertEquals("45", Eval2.eval(code, 10));
     }
     @Test
     public void testFor3() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 int sum=0;
 for( int i=0; i<arg; )
     sum += i++;
 return sum;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Loop,0,(Phi_sum+Phi(Loop,0,(Phi_i+1))));", stop.toString());
-        assertEquals(3L, Evaluator.evaluate(stop, 3));
-        assertEquals(45L, Evaluator.evaluate(stop, 10));
+        code.parse().opto();
+        assertEquals("return Phi(Loop,0,(Phi_sum+Phi(Loop,0,(Phi_i+1))));", code.print());
+        assertEquals("3", Eval2.eval(code, 3));
+        assertEquals("45", Eval2.eval(code, 10));
     }
     @Test
     public void testFor4() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 int sum=0;
 for( int i=0; i<arg; i++ )
     sum += i;
 return i;
 """);
-        try { parser.parse().iterate(); fail(); }
+        try { code.parse().opto(); fail(); }
         catch( Exception e ) { assertEquals("Undefined name 'i'",e.getMessage()); }
     }
     @Test
     public void testFor5() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 for(;;arg++;) {}
 """);
-        try { parser.parse().iterate(); fail(); }
+        try { code.parse().opto(); fail(); }
         catch( Exception e ) { assertEquals("Syntax error, expected Unexpected code after expression: ;",e.getMessage()); }
     }
 
@@ -421,36 +477,36 @@ for(;;arg++;) {}
     // ---------------------------------------------------------------
     @Test
     public void testForward0() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 struct A{
     B? f1;
     B? f2;
 };
 return new A;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return A;", stop.toString());
-        assertEquals("Obj<A>{f1=null,f2=null}", Evaluator.evaluate(stop).toString());
+        code.parse().opto();
+        assertEquals("return A;", code.print());
+        assertEquals("A{f1=null,f2=null}", Eval2.eval(code,0));
     }
 
     @Test
     public void testForward1() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 struct A{
     B?[]? nil_array_of_b;
     B?[]  not_array_of_b = new B?[0];
 };
 return new A.not_array_of_b;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return (const)[*B?];", stop.toString());
-        assertEquals("Obj<[*B?]>{#=0,[]=[]}", Evaluator.evaluate(stop).toString());
+        code.parse().opto();
+        assertEquals("return (const)[*B?];", code.print());
+        assertEquals("*B?[]", Eval2.eval(code,0));
     }
 
     // ---------------------------------------------------------------
     @Test
     public void testLinkedList2() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 struct LLI { LLI? next; int i; };
 LLI? !head = null;
 while( arg-- )
@@ -461,14 +517,14 @@ for( ; ptr; ptr = ptr.next )
     sum += ptr.i;
 return sum;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return Phi(Loop,0,(Phi_sum+.i));", stop.toString());
-        assertEquals(45L, Evaluator.evaluate(stop, 10));
+        code.parse().opto();
+        assertEquals("return Phi(Loop,0,(Phi_sum+.i));", code.print());
+        assertEquals("45", Eval2.eval(code, 10));
     }
 
     @Test
     public void sieveOfEratosthenes() {
-        Parser parser = new Parser(
+        CodeGen code = new CodeGen(
 """
 var ary = new bool[arg], primes = new int[arg];
 var nprimes=0, p=0;
@@ -492,14 +548,9 @@ for( int j=0; j<nprimes; j++ )
     rez[j] = primes[j];
 return rez;
 """);
-        StopNode stop = parser.parse().iterate();
-        assertEquals("return [int];", stop.toString());
-        Evaluator.Obj obj = (Evaluator.Obj)Evaluator.evaluate(stop, 20);
-        assertEquals("[int] {int #; int ![]; }",obj.struct().toString());
-        long nprimes = (Long)obj.fields()[0];
-        long[] primes = new long[]{2,3,5,7,11,13,17,19};
-        for( int i=0; i<nprimes; i++ )
-            assertEquals(primes[i],(long)(Long)obj.fields()[i+1]);
+        code.parse().opto().typeCheck().GCM();
+        assertEquals("return [int];", code.print());
+        assertEquals("int[ 2,3,5,7,11,13,17,19]",Eval2.eval(code, 20));
     }
 
 }
diff --git a/src/test/java/com/seaofnodes/simple/Chapter18Test.java b/src/test/java/com/seaofnodes/simple/Chapter18Test.java
new file mode 100644
index 00000000..60f9b847
--- /dev/null
+++ b/src/test/java/com/seaofnodes/simple/Chapter18Test.java
@@ -0,0 +1,345 @@
+package com.seaofnodes.simple;
+
+import org.junit.Test;
+import static org.junit.Assert.*;
+import static org.junit.Assert.fail;
+import org.junit.Ignore;
+
+public class Chapter18Test {
+
+    @Test
+    public void testJig() {
+        CodeGen code = new CodeGen(
+"""
+return 0;
+""");
+        code.parse().opto().typeCheck().GCM().localSched();
+        assertEquals("return 0;", code._stop.toString());
+        assertEquals("0", Eval2.eval(code,  2));
+    }
+
+    @Test
+    public void testPhiParalleAssign() {
+        CodeGen code = new CodeGen(
+"""
+int a = 1;
+int b = 2;
+while(arg--) {
+  int t = a;
+  a = b;
+  b = t;
+}
+return a;
+""");
+        code.parse().opto().typeCheck().GCM();
+        assertEquals("return Phi(Loop,1,Phi(Loop,2,Phi_a));", code._stop.toString());
+        assertEquals("1", Eval2.eval(code,  0));
+        assertEquals("2", Eval2.eval(code,  1));
+        assertEquals("1", Eval2.eval(code,  2));
+        assertEquals("2", Eval2.eval(code,  3));
+    }
+
+
+    // ---------------------------------------------------------------
+    @Test
+    public void testType0() {
+        CodeGen code = new CodeGen(
+"""
+{int -> int}? x2 = null; // null function ptr
+return x2;
+""");
+        code.parse().opto();
+        assertEquals("return null;", code._stop.toString());
+        assertEquals("null", Eval2.eval(code, 0 ) );
+    }
+
+    @Test
+    public void testFcn0() {
+        CodeGen code = new CodeGen(
+"""
+{int -> int}? sq = { int x ->
+    x*x;
+};
+return sq;
+""");
+        code.parse().opto();
+        assertEquals("Stop[ return { sq}; return (Parm_x(sq,int)*x); ]", code._stop.toString());
+        assertEquals("{ sq}", Eval2.eval(code, 3));
+    }
+
+    @Test
+    public void testFcn1() {
+        CodeGen code = new CodeGen(
+"""
+var sq = { int x ->
+    x*x;
+};
+return sq(arg)+sq(3);
+""");
+        code.parse().opto();
+        assertEquals("Stop[ return (sq( 3)+sq( arg)); return (Parm_x(sq,int,3,arg)*x); ]", code._stop.toString());
+        assertEquals("13", Eval2.eval(code, 2));
+    }
+
+    // Function scope test
+    @Test
+    public void testFcn2() {
+        CodeGen code = new CodeGen(
+"""
+int cnt=1;
+return { -> cnt; };
+""");
+        try { code.parse().opto(); fail(); }
+        catch( Exception e ) { assertEquals("Variable 'cnt' is out of function scope and must be a final constant",e.getMessage()); }
+    }
+
+    // Function scope test
+    @Test
+    public void testFcn3() {
+        CodeGen code = new CodeGen(
+"""
+val cnt=2;
+return { -> cnt; }();
+""");
+        code.parse().opto();
+        assertEquals("return 2;", code._stop.toString());
+        assertEquals("2", Eval2.eval(code, 0));
+    }
+
+    // Function variables
+    @Test
+    public void testFcn4() {
+        CodeGen code = new CodeGen(
+"""
+var fcn = arg ? { int x -> x*x; } : { int x -> x+x; };
+return fcn(3);
+""");
+        code.parse().opto();
+        assertEquals("Stop[ return Phi(Region,{ int -> int #1},{ int -> int #2})( 3); return (Parm_x($fun,int,3)*x); return (Parm_x($fun,int,3)*2); ]", code._stop.toString());
+        assertEquals("6", Eval2.eval(code, 0));
+        assertEquals("9", Eval2.eval(code, 1));
+    }
+
+    // Recursive factorial test
+    @Test
+    public void testFcn5() {
+        CodeGen code = new CodeGen("val fact = { int x -> x <= 1 ? 1 : x*fact(x-1); }; return fact(arg);");
+        code.parse().opto();
+        assertEquals("Stop[ return fact( arg); return Phi(Region,1,(Parm_x(fact,int,arg,(x-1))*fact( Sub))); ]", code._stop.toString());
+        assertEquals( "1", Eval2.eval(code, 0));
+        assertEquals( "1", Eval2.eval(code, 1));
+        assertEquals( "2", Eval2.eval(code, 2));
+        assertEquals( "6", Eval2.eval(code, 3));
+        assertEquals("24", Eval2.eval(code, 4));
+    }
+
+    @Test
+    public void testFcn6() {
+        CodeGen code = new CodeGen(
+"""
+struct S { int i; };
+val newS = { int x -> return new S { i=x; }; };
+return newS(1).i;
+""");
+        code.parse().opto().typeCheck().GCM();
+        assertEquals("return 1;", code._stop.toString());
+        assertEquals("1", Eval2.eval(code,  0));
+    }
+
+    // Double forward reference
+    @Test
+    public void testFcn7() {
+        CodeGen code = new CodeGen(
+"""
+if( arg ? f : g ) return 1;
+val f = {->1;};
+val g = {->2;};
+return 2;
+""");
+        code.parse().opto().typeCheck().GCM();
+        assertEquals("Stop[ return 1; return 1; return 2; ]", code._stop.toString());
+        assertEquals("1", Eval2.eval(code,  0));
+    }
+
+    @Test
+    public void testFcn8() {
+        CodeGen code = new CodeGen(
+"""
+{int -> int}? i2i = null;
+var id = {{int->int} f-> return f;};
+for(;;) {
+    if (i2i) return i2i(arg);
+    var x = {int i-> return i;};
+    arg = x(3);
+    i2i = id(x);
+}
+""");
+        code.parse().opto().typeCheck().GCM().localSched();
+        assertEquals("Stop[ return x( Phi(Loop,arg,x( 3))); return Parm_i(x,int,3,Phi_arg); ]", code._stop.toString());
+        assertEquals("3", Eval2.eval(code,  0));
+    }
+
+
+    @Test
+    public void testFcn9() {
+        CodeGen code = new CodeGen(
+"""
+{int -> int}? i2i = null;
+for(;;) {
+    if (i2i) return i2i(arg);
+    var x = {int i-> return i;};
+    arg = x(3);
+}
+""");
+        code.parse().opto().typeCheck().GCM().localSched();
+        assertEquals("return Top;", code._stop.toString());
+        assertEquals(null, Eval2.eval(code,  0));
+    }
+
+    // Function break
+    @Test
+    public void testErr1() {
+        CodeGen code = new CodeGen(
+"""
+for(;;) {
+    val f = { ->
+        break;
+    };
+    f();
+    return 2;
+}
+return 1;
+""");
+        try { code.parse().opto(); fail(); }
+        catch( Exception e ) { assertEquals("No active loop for a break or continue",e.getMessage()); }
+    }
+
+    // Calling and inlining a null function
+    @Test
+    public void testErr2() {
+        CodeGen code = new CodeGen(
+"""
+{int -> int}? !i2i = { int i -> return i; };
+for(;;) {
+    if (i2i(2) == arg) break;
+    i2i = null;
+}
+""");
+        try { code.parse().opto().typeCheck(); fail(); }
+        catch( Exception e ) { assertEquals("Might be null calling { int -> int #1}?",e.getMessage()); }
+    }
+
+
+    @Test
+    public void testErr3() {
+        CodeGen code = new CodeGen(
+"""
+val f = { int i, int j -> return i+j; };
+return f();
+""");
+        try { code.parse().opto().typeCheck(); fail(); }
+        catch( Exception e ) { assertEquals("Expecting 2 arguments, but found 0",e.getMessage()); }
+    }
+
+
+    @Test
+    public void testErr4() {
+        CodeGen code = new CodeGen(
+"""
+struct S {
+    {int} f = { -> x(); return 0; }; // Do not let fref x be a field
+};
+val x = { -> return 1; };
+S? s = null;
+for(;;) {
+    if (s) return s.x;
+}
+""");
+        try { code.parse().opto().typeCheck(); fail(); }
+        catch( Exception e ) { assertEquals("Accessing unknown field 'x' from '*S'",e.getMessage()); }
+    }
+
+    @Test
+    public void testErr5() {
+        CodeGen code = new CodeGen(
+"""
+val g = { ->
+    g();
+};
+return 0;
+""");
+        try { code.parse().opto().typeCheck(); fail(); }
+        catch( Exception e ) { assertEquals("No defined return type",e.getMessage()); }
+    }
+
+
+    // Mutual recursion.  Fails without SCCP to lift the recursive return types.
+    @Ignore @Test
+    public void testFcnMutRec() {
+        CodeGen code = new CodeGen(
+"""
+val is_even = { int x -> x ? is_odd (x-1) : true ; };
+val is_odd  = { int x -> x ? is_even(x-1) : false; };
+return is_even(arg);
+""");
+        code.parse().opto();
+        assertEquals("Stop[ return is_even( arg); return Phi(Region,Phi(Region,is_even( ((Parm_x(is_even,int,arg,Sub)-1)-1)),0),1); ]", code._stop.toString());
+        assertEquals("1", Eval2.eval(code, 0));
+        assertEquals("0", Eval2.eval(code, 1));
+        assertEquals("1", Eval2.eval(code, 2));
+        assertEquals("0", Eval2.eval(code, 3));
+    }
+
+    // Forward ref to 'x' means that
+    @Ignore @Test
+    public void testForwardRef1() {
+        CodeGen code = new CodeGen(
+"""
+struct S {
+    { int } f = { -> return x(); };
+};
+val x = { -> return 1; };
+S? s = null;
+for(;;) {
+    if (s) return s.f;
+}
+""");
+        code.parse().opto().typeCheck().GCM();
+        assertEquals("return 0;", code._stop.toString());
+        assertEquals("0", Eval2.eval(code,  0));
+    }
+
+    // Inline hidden called more than once
+    @Test
+    public void testInline() {
+        CodeGen code = new CodeGen(
+"""
+{int->int}?! i2i = {int i->return i;};
+{{int->int}->{int->int}}! f2f = {{int->int} f->return f;};
+val o = i2i;
+if (arg) i2i = null;
+if (i2i) return i2i(arg);
+return f2f(o)(1);
+""");
+        code.parse().opto().typeCheck().GCM().localSched();
+        assertEquals("Stop[ return Phi(Region,o( arg),o( 1)); return Parm_i(o,int,arg,1); ]", code._stop.toString());
+        assertEquals("1", Eval2.eval(code,  2));
+    }
+
+    @Test
+    public void testOperField() {
+        CodeGen code = new CodeGen(
+"""
+struct Person {
+    int coffee_count;
+};
+Person !p = new Person;
+p.coffee_count += 1;
+return p.coffee_count;
+""");
+        code.parse().opto().typeCheck().GCM().localSched();
+        assertEquals("return 1;", code._stop.toString());
+        assertEquals("1", Eval2.eval(code,  2));
+    }
+
+}
diff --git a/src/test/java/com/seaofnodes/simple/Eval2.java b/src/test/java/com/seaofnodes/simple/Eval2.java
new file mode 100644
index 00000000..2da834e5
--- /dev/null
+++ b/src/test/java/com/seaofnodes/simple/Eval2.java
@@ -0,0 +1,446 @@
+package com.seaofnodes.simple;
+
+import com.seaofnodes.simple.type.*;
+import com.seaofnodes.simple.node.*;
+import java.util.*;
+
+public abstract class Eval2 {
+
+    // A mapping from Node ID to evaluation data Object.
+    // Data Objsts are a boxed Long or Double; or an Object[] of fields, which
+    // themselves are just more Objects.
+    private static class Frame {
+        private static int UID=1;
+
+        private final IdentityHashMap<Node,Object> _data;
+        private Frame _prior;   // Prior frame in this sequence, means when making a new frame we can find old stuff
+        private int _refcnt;    // TODO: Use this in a sentence (free/recycle unused stack frames)
+        final int _uid = UID++; // Debugging aid
+        Frame(Frame prior) {
+            _prior = prior;
+            if( prior!=null ) prior._refcnt++;
+            _data = new IdentityHashMap<>();
+            _refcnt = 1;
+        }
+
+        // Dec ref count
+        void dec() {
+            assert _refcnt>0;
+            if( --_refcnt == 0 ) {
+                Frame prior = _prior;
+                _prior = null;
+                _data.clear();
+                // TODO: FREE LIST?
+                if( prior!=null )
+                    prior.dec();
+            }
+        }
+
+        // Put a mapping from Node->Object
+        Node put(Node n, Object d) {
+            assert d!=null;
+            return put0(n,d);
+        }
+        // Put a mapping from Node->Object?
+        Node put0(Node n, Object d) {
+            assert _refcnt>0;
+            _data.put(n,d);
+            return n;
+        }
+        // Get a mapped Node, perhaps using the prior stack frame crawl
+        Object get(Node n) {
+            assert _refcnt>0;
+            Object d = _data.get(n);
+            return d != null ? d
+                : _prior == null ? null
+                : _prior.get(n);
+        }
+
+        // Short debugging print
+        public String p() {
+            return "#"+_uid + (_prior==null ? "" : " >> " + _prior.p());
+        }
+        // Long debugging print
+        @Override public String toString() {
+            String s = "";
+            if( _prior != null ) s+= _prior+" << ";
+            s += "#"+_uid+"[ ";
+            for( Node n : _data.keySet() )
+                s += n + ":" + _data.get(n) + ",";
+            s += "]";
+
+            return s;
+        }
+    }
+
+    // Classic Closure; an environment (stack of frames) and an execution point
+    private static class Closure {
+        // Where to return too; either a CallEnd or a Function
+        final CFGNode _cc;
+
+        // Stack frame at the execution point.  Includes Closures which
+        // recursively include other stack frames
+        private Frame _frame;
+
+        Closure(CFGNode cc, Frame frame) {
+            _cc = cc;           // One of Fun, CallEnd or Stop (null)
+            _frame = frame;
+            assert _frame._refcnt >=0;
+            _frame._refcnt++;
+        }
+
+        FunNode fun() { return (FunNode)_cc; }
+        CallEndNode cend() { return (CallEndNode)_cc; }
+        boolean isStop() { return _cc instanceof StopNode; } // or Stop
+
+        //
+        void pushFrame() {
+            _frame = new Frame(_frame);
+            _frame._refcnt++;
+        }
+
+        @Override public String toString() {
+            return _cc.toString();
+        }
+    }
+
+    // CodeGen has the linker tables
+    public static CodeGen CODE;
+
+    // Current active Frame, to avoid having to pass it everywhere
+    public static Frame F;
+
+    public static String eval( CodeGen code, long arg ) { return eval(code,arg,1000); }
+    public static String eval( CodeGen code, long arg, int timeout ) {
+        SB trace = null; // new SB(); // TRACE, set to null for off, new SB() for on
+        // Force local scheduling phase
+        if( code._phase.ordinal() < CodeGen.Phase.TypeCheck .ordinal() )  code.typeCheck();
+        if( code._phase.ordinal() < CodeGen.Phase.Schedule  .ordinal() )  code.GCM();
+        if( code._phase.ordinal() < CodeGen.Phase.LocalSched.ordinal() )  code.localSched();
+        // Set global, so don't have to pass everywhere
+        CODE = code;
+
+        // Timer for when we run too long.  Ticks once per backedge or function call
+        int loopCnt = 0;
+
+        // Current value for each Node; boxed Long or Double; or an Object[] of
+        // fields, which themselves are just more Objects.
+        F = new Frame(null);
+
+        // Start at the START
+        CFGNode BB = code._start, prior = null;
+        // Return from main hits Stop
+        F.put(BB,new Closure(code._stop,F));
+
+
+        // ------------
+        // Evaluate until exit or timeout.  Each outer loop step computes
+        // all data nodes under some new Control.
+        while( true ) {
+            assert BB!=null;
+            traceCtrl(BB,trace);
+            if( trace!=null ) System.out.println(F.p());
+
+            // Parallel assign Phis
+            int i = BB instanceof RegionNode r
+                    ? parallelAssignPhis(r,prior,arg,trace)
+                    : 0;
+
+            // Compute the data nodes until BB control
+            for( ; i < BB.nOuts(); i++ )
+                if( !(BB.out(i) instanceof CFGNode) )
+                    step(BB.out(i), trace);
+
+            // Find the next control target
+            prior = BB;
+            BB = BB.uctrl();      // Next unique control target
+            switch( prior ) {
+            case StartNode start:  F = new Frame(F); break; // Frame for the call to main, as-if Called
+            case CallNode  call :  BB = call(call); break;
+            case IfNode    iff  :  Object p = val(iff.pred()); BB = iff.cproj( p==null || (p instanceof Long x && x==0L)  ? 1 : 0);  break;
+            case ReturnNode ret :  if( clj(ret.rpc()).isStop() ) return exit(ret); else BB = ret(ret); break;
+            case FunNode   fun  :  if( loopCnt++ > timeout ) return null;  break; // Timeout
+            case LoopNode  loop :  if( loopCnt++ > timeout ) return null;  break; // Timeout
+            case CallEndNode cend: break;
+            case CProjNode cproj:  break;
+            case RegionNode r   :  break;
+            default:               throw Utils.TODO();
+            }
+            assert !BB.isDead();
+        }
+    }
+
+
+    // Phi cache; size is limited to number of Phis at a merge point
+    private static final Object[] PHICACHE = new Object[256];
+    static int parallelAssignPhis(RegionNode r, CFGNode prior, long arg, SB trace) {
+
+        // Compute input path on Phis for this Region
+        int path = r._inputs.find( prior );
+        // Parameters read from prior frame, Phis from local frame
+        Frame frame = (r instanceof FunNode ? F._prior : F);
+        boolean isMain = r instanceof FunNode fun && fun.sig().isa(TypeFunPtr.MAIN);
+
+        // Parallel assign Phis.  First parallel read and cache
+        int i;
+        for( i = 0; i < r.nOuts(); i++ ) {
+            if( !(r.out(i) instanceof PhiNode phi) ) break;
+            if( isMain && phi instanceof ParmNode parm && parm._idx==2 )
+                PHICACHE[i] = arg; // Reading the initial arguments to main()
+            else {
+                Node n = phi instanceof ParmNode parm
+                    // RPC reads the Call directly;
+                    // Parms may not be linked, so read call args directly
+                    ? (parm._idx==0 ? prior : prior.in(parm._idx))
+                    // Phis read from path input
+                    :  phi.in(path);
+                PHICACHE[i] = frame.get(n);
+            }
+        }
+        // Parallel assign; might assign before read, so read from cache
+        for( int j=0; j < i; j++ )
+            traceData(F.put0(r.out(j),PHICACHE[j]),trace);
+        // Return point in basic block past last Phi
+        return i;
+    }
+
+
+    // Make a call.
+    private static CFGNode call( CallNode call ) {
+        // Set up the Return PC and return frame (which is just the current frame).
+        // Really making a Continuation, but it's just a Closure
+        Closure cont = new Closure(call.cend(),F);
+        // Set the return continuation into the current frame RPC
+        F.put(call, cont );
+        // Next Frame to use
+        F = new Frame(F);
+        // Target function and environment
+        return CODE.link(tfp(call.fptr()));
+    }
+
+    private static CFGNode ret( ReturnNode ret ) {
+        // Fetch return expression value and continuation from current frame
+        Object rez = val(ret.expr());
+        Closure cont = clj(ret.rpc());
+        // Lower Frame reference count; might delete frame
+        F.dec();                // Lower ref count
+        // Install replacement Frame; set return result over the CallEnd
+        F = cont._frame;
+        F.put0(cont._cc,rez);   // Set return value into CallEnd
+        return cont._cc;        // Return CallEnd as the new control
+    }
+
+    private static String exit( ReturnNode ret ) {
+        return prettyPrint(ret.expr()._type,val(ret.expr()));
+    }
+
+    // Take a worklist step: one data op from the current Control is updated.
+    private static void step(Node n, SB trace) {
+        if( n instanceof PhiNode ) return;
+        // Compute new value
+        F.put0(n,compute(n));
+        traceData(n,trace);
+        // Also do any following projections, which are not in the local schedule otherwise
+        if( n instanceof MultiNode )
+            for( Node use : n._outputs )
+                step(use,trace);
+    }
+
+    // From here down shamelessly copied from Evaluator, written by @Xmilia
+    private static Object compute( Node n ) {
+        return switch( n ) {
+        case AddFNode     adf  -> d(adf.in(1)) +  d(adf.in(2));
+        case AddNode      add  -> x(add.in(1)) +  x(add.in(2));
+        case AndNode      and  -> x(and.in(1)) &  x(and.in(2));
+        case BoolNode.EQF eqf  -> d(eqf.in(1)) == d(eqf.in(2)) ? 1L : 0L;
+        case BoolNode.LEF lef  -> d(lef.in(1)) <= d(lef.in(2)) ? 1L : 0L;
+        case BoolNode.LTF ltf  -> d(ltf.in(1)) <  d(ltf.in(2)) ? 1L : 0L;
+        case BoolNode.EQ  eq   -> Objects.equals(val(eq.in(1)), val(eq.in(2))) ? 1L : 0L; // Bool EQ supports pointers, nil, and integers
+        case BoolNode.LE  le   -> x(le .in(1)) <= x(le .in(2)) ? 1L : 0L;
+        case BoolNode.LT  lt   -> x(lt .in(1)) <  x(lt .in(2)) ? 1L : 0L;
+        case CastNode    cast  -> val(cast.in(1));
+        case ConstantNode con  -> con(con._con);
+        case DivFNode     dvf  -> d(dvf.in(2))==0 ? 0D : d(dvf.in(1)) /  d(dvf.in(2));
+        case DivNode      div  -> x(div.in(2))==0 ? 0L : x(div.in(1)) /  x(div.in(2));
+        case LoadNode     ld   -> load(ld);
+        case MinusFNode   mnf  -> - d(mnf.in(1));
+        case MinusNode    sub  -> - x(sub.in(1));
+        case MulFNode     mlf  -> d(mlf.in(1)) *  d(mlf.in(2));
+        case MulNode      mul  -> x(mul.in(1)) *  x(mul.in(2));
+        case NewNode      alloc-> alloc(alloc);
+        case NotNode      not  -> x(not.in(1)) == 0 ? 1L : 0L;
+        case OrNode       or   -> x(or .in(1)) |  x(or .in(2));
+        case ProjNode     proj -> proj._type instanceof TypeMem ? "$mem" : val(proj.in(0));
+        case ReadOnlyNode read -> val(read.in(1));
+        case SarNode      sar  -> x(sar.in(1)) >> x(sar.in(2));
+        case MemMergeNode merge-> "$mem";
+        case ShlNode      shl  -> x(shl.in(1)) << x(shl.in(2));
+        case ShrNode      shr  -> x(shr.in(1)) >>>x(shr.in(2));
+        case StoreNode    st   -> store(st);
+        case SubNode      sub  -> x(sub.in(1)) -  x(sub.in(2));
+        case SubFNode     sbf  -> d(sbf.in(1)) -  d(sbf.in(2));
+        case ToFloatNode  toflt-> (double)x(toflt.in(1));
+        case XorNode      xor  -> x(xor.in(1)) ^  x(xor.in(2));
+        default -> throw Utils.TODO();
+        };
+    }
+
+    // Fetch without unboxing, searching up-Frame
+    static Object val( Node n ) { return F.get(n); }
+    // Fetch and unbox as primitive long
+    static long   x( Node n ) { Object d = F.get(n); return d==null ? 0 : (Long)  F.get(n);  }
+    // Fetch and unbox as primitive double
+    static double d( Node n ) { Object d = F.get(n); return d==null ? 0 : (Double)F.get(n);  }
+    // Fetch and unbox a function constant
+    static TypeFunPtr tfp(Node n) { return (TypeFunPtr)F.get(n); }
+    // Fetch and unbox a closure
+    static Closure clj(Node n) { return (Closure)F.get(n); }
+
+    // Java box ints and floats.  Other things can just be null or some informative string
+    private static Object con( Type t ) {
+        return switch ( t ) {
+        case TypeInteger i -> i.isConstant() ? (Long  )i.value() : "INT";
+        case TypeFloat   f -> f.isConstant() ? (Double)f.value() : "FLT";
+        case TypeMemPtr tmp -> tmp;
+        case TypeFunPtr tfp -> tfp;
+        case TypeMem mem -> "MEM";
+        default -> null;
+        };
+    }
+
+    // Convert array size to array element count
+    private static int offToIdx( long off, TypeStruct t) {
+        off -= t.aryBase();
+        int scale = t.aryScale();
+        long mask = (1L << scale)-1;
+        assert (off & mask) == 0;
+        return (int)(off>>scale);
+    }
+
+    // Builds and returns a pointer Object
+    private static Object alloc(NewNode alloc) {
+        TypeStruct type = alloc._ptr._obj;
+        if( type.isAry() ) {
+            long sz = (Long)val(alloc.in(1));
+            long x = offToIdx(sz, type);
+            int n = (int)x;
+            if( n!=x || n<0 )
+                throw new NegativeArraySizeException(""+n);
+            Object[] ary = new Object[n]; // Array body
+            var elem = type._fields[1]._type;
+            if (elem instanceof TypeInteger) {
+                Arrays.fill( ary, 0L );
+            } else if (elem instanceof TypeFloat) {
+                Arrays.fill( ary, 0D );
+            } else {
+                assert elem instanceof TypeMemPtr || elem instanceof TypeFunPtr;
+            }
+            return ary;
+        }
+
+        int num = type._fields.length;
+        Object[] ptr = new Object[num];
+        for( int i=0; i<num; i++ )
+            ptr[i] = val(alloc.in(2+i+num));
+        return ptr;
+    }
+
+    private static Object load( LoadNode ld ) {
+        TypeMemPtr tmp = (TypeMemPtr)ld.ptr()._type;
+        Object[] fs = (Object[])val(ld.ptr());
+        if( ld._name.equals("#") )
+            return (long)fs.length;
+        int idx = tmp._obj.isAry()
+            ? offToIdx(x(ld.off()),tmp._obj)
+            : tmp._obj.find(ld._name);
+        return fs[idx];
+    }
+
+    private static Object store( StoreNode st ) {
+        TypeMemPtr tmp = (TypeMemPtr)st.ptr()._type;
+        Object[] fs = (Object[])val(st.ptr());
+        int idx = tmp._obj.isAry()
+            ? offToIdx(x(st.off()),tmp._obj)
+            : tmp._obj.find(st._name);
+        Object val = val(st.val());
+        fs[idx] = val;
+        return "$mem";
+    }
+
+
+    // ------------------------------------------------------------------------
+    private static final IdentityHashMap<Object,Object> VISIT = new IdentityHashMap<>();
+
+
+    static void traceCtrl( CFGNode BB, SB sb ) {
+        if( sb==null ) return;
+        IRPrinter.printLine(BB,sb.p("--- "));
+        System.out.print(sb);
+        sb.clear();
+    }
+    static void traceData( Node n, SB sb ) {
+        if( sb==null ) return;
+        IRPrinter.printLine(n,sb).unchar();
+        _print( n._type, F.get(n), sb.p('\t'), VISIT );
+        System.out.println(sb);
+        sb.clear();
+        VISIT.clear();
+    }
+
+    // Use type to print x as a string.  Uses a new VISIT table so the debugger
+    // doesn't try to reuse VISIT if stopping mid-print.  The trace code reuses
+    // VISIT endlessly for some minor speed hope
+    static String prettyPrint( Type t, Object x ) { return _print(t,x,new SB(), new IdentityHashMap<>()).toString(); }
+    static SB _print( Type t, Object x, SB sb, IdentityHashMap<Object,Object> visit ) {
+        if( x instanceof String s ) return sb.p(s);
+        if( x == null ) return sb.p("null");
+        return switch( t ) {
+        case TypeInteger i -> sb.p(  (Long)x);
+        case TypeFloat   f -> sb.p((Double)x);
+        case TypeMemPtr tmp -> {
+            if( visit.containsKey(x) ) yield sb.p("$cyclic");
+            visit.put(x,x);
+            // Since never can close the type cycle, without cyclic types, have
+            // to handle FRefs even here
+            if( tmp.isFRef() )
+                tmp = tmp.makeFrom(((TypeMemPtr)Parser.TYPES.get(tmp._obj._name))._obj);
+
+            Object[] xs = (Object[])x; // Array of fields
+            if( tmp._obj.isAry() ) {
+                Type elem = tmp._obj._fields[1]._type;
+                if( elem == TypeInteger.U8 ) {
+                    // Shortcut u8[] as a String
+                    for( Object o : xs )
+                        sb.p((char)(long)(Long)o);
+                } else {
+                    // Array of elements
+                    elem.print(sb).p("[ ");
+                    for( Object o : xs )
+                        _print( elem, o, sb, visit ).p( "," );
+                    sb.unchar().p("]");
+                }
+            } else {
+                sb.p(tmp._obj._name).p("{");
+                Field[] flds = tmp._obj._fields;
+                for( int i=0; i<flds.length; i++ )
+                    _print( flds[i]._type,xs[i], sb.p(flds[i]._fname).p("="), visit ).p(",");
+                sb.unchar().p("}");
+            }
+            yield sb;
+        }
+        case TypeFunPtr tfp -> sb.p(x.toString());
+        case TypeRPC rpc -> sb.p(x.toString());
+        case TypeMem mem -> sb.p("$mem");
+        case TypeTuple tt -> {
+            if( tt._types.length>1 && tt._types[1] instanceof TypeMemPtr )
+                // Assume a NewNode
+                yield _print( tt._types[1], x, sb, visit );
+            throw Utils.TODO();
+        }
+        case Type tt -> {
+            if( tt == Type.NIL ) yield sb.p("null");
+            throw Utils.TODO();
+        }
+        };
+    }
+}
diff --git a/src/test/java/com/seaofnodes/simple/FuzzerWrap.java b/src/test/java/com/seaofnodes/simple/FuzzerWrap.java
index eaeed8e2..d67b2065 100644
--- a/src/test/java/com/seaofnodes/simple/FuzzerWrap.java
+++ b/src/test/java/com/seaofnodes/simple/FuzzerWrap.java
@@ -28,7 +28,7 @@ public class FuzzerWrap {
         Random R = new Random(System.currentTimeMillis());
         var fuzzer = new Fuzzer();
         for (int i=0; i<100; i++)
-            fuzzer.fuzzPeeps(R.nextLong());
+            fuzzer.fuzzPeeps( R.nextLong());
         assertTrue(fuzzer.noExceptions());
     }
 
diff --git a/src/test/java/com/seaofnodes/simple/MergeSortTest.java b/src/test/java/com/seaofnodes/simple/MergeSortTest.java
new file mode 100644
index 00000000..d48449d5
--- /dev/null
+++ b/src/test/java/com/seaofnodes/simple/MergeSortTest.java
@@ -0,0 +1,65 @@
+package com.seaofnodes.simple;
+
+import org.junit.Test;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.fail;
+
+public class MergeSortTest {
+
+    @Test
+    public void testMergeSort() {
+        CodeGen code = new CodeGen(
+"""
+// based on the top-down version from https://en.wikipedia.org/wiki/Merge_sort
+
+val merge_sort = { int[] a, int[] b, int n ->
+    copy_array(a, 0, n, b);
+    split_merge(a, 0, n, b);
+};
+
+val split_merge = { int[] b, int begin, int end, int[] a ->
+    if (end - begin <= 1)
+        return 0;
+    int middle = (end + begin) / 2;
+    split_merge(a, begin, middle, b);
+    split_merge(a, middle, end, b);
+    merge(b, begin, middle, end, a);
+    return 0;
+};
+
+val merge = { int[] b, int begin, int middle, int end, int[] a ->
+    int i = begin, j = middle;
+
+    for (int k = begin; k < end; k++) {
+        // && and ||
+        bool cond = false;
+        if (i < middle) {
+            if (j >= end)          cond = true;
+            else if (a[i] <= a[j]) cond = true;
+        }
+        if (cond) b[k] = a[i++];
+        else      b[k] = a[j++];
+    }
+};
+
+val copy_array = { int[] a, int begin, int end, int[] b ->
+    for (int k = begin; k < end; k++)
+        b[k] = a[k];
+};
+
+int[] !a = new int[arg];
+int[] !b = new int[a#];
+
+for (int i = 0; i < a#; i++)
+    a[i] = a# - i;
+
+merge_sort(a, b, a#);
+
+return a;
+""");
+        code.parse().opto();
+        assertEquals("Stop[ return [int]; return 0; ]", code._stop.toString());
+        assertEquals("int[ 1,2,3,4,5,6,7,8,9,10,11]", Eval2.eval(code, 11));
+    }
+
+}
diff --git a/src/test/java/com/seaofnodes/simple/SchedulerTest.java b/src/test/java/com/seaofnodes/simple/SchedulerTest.java
index c67217af..e869e133 100644
--- a/src/test/java/com/seaofnodes/simple/SchedulerTest.java
+++ b/src/test/java/com/seaofnodes/simple/SchedulerTest.java
@@ -20,7 +20,7 @@ public class SchedulerTest {
     @Test
     @Ignore
     public void testJig() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 struct S {
     int f;
 }
@@ -31,14 +31,14 @@ if (arg) v.f=1;
 return i;
 """);
         StopNode._disablePeephole = true;
-        StopNode stop = parser.parse();//.iterate();
-        var eval = new Evaluator(stop);
+        code.parse();//.opto();
+        var eval = new Evaluator(code._stop);
         assertEquals(2L, eval.evaluate(1, 10));
     }
 
     @Test
     public void testStoreInIf() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 struct S {
     int f;
 };
@@ -46,15 +46,15 @@ S !v0=new S;
 if(arg) v0.f=1;
 return v0;
 """);
-        StopNode stop = parser.parse().iterate();
-        var eval = new Evaluator(stop);
+        code.parse().opto();
+        var eval = new Evaluator(code._stop);
         assertObj(eval.evaluate(0, 10), "S", 0L);
         assertObj(eval.evaluate(1, 10), "S", 1L);
     }
 
     @Test
     public void testStoreInIf2() {
-        Parser parser = new Parser("""
+        CodeGen code = new CodeGen("""
 struct S {
     int f;
 };
@@ -65,8 +65,8 @@ i=v.f;
 if (arg) v.f=1;
 return i;
 """);
-        StopNode stop = parser.parse().iterate();
-        var eval = new Evaluator(stop);
+        code.parse().opto();
+        var eval = new Evaluator(code._stop);
         assertEquals(2L, eval.evaluate(0, 10));
         assertEquals(2L, eval.evaluate(1, 10));
     }
diff --git a/src/test/java/com/seaofnodes/simple/TypeTest.java b/src/test/java/com/seaofnodes/simple/TypeTest.java
index 1cb97cf6..d94f5b5a 100644
--- a/src/test/java/com/seaofnodes/simple/TypeTest.java
+++ b/src/test/java/com/seaofnodes/simple/TypeTest.java
@@ -2,9 +2,7 @@ package com.seaofnodes.simple;
 
 import com.seaofnodes.simple.type.*;
 import org.junit.Assert;
-import org.junit.Ignore;
 import org.junit.Test;
-import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertSame;
 
 public class TypeTest {
@@ -12,19 +10,23 @@ public class TypeTest {
     // Test basic properties and GLB
     @Test
     public void testTypeAdHoc() {
+        Assert.assertEquals( Type.BOTTOM, TypeInteger.TRUE.meet(TypeNil.NIL) );
+        Assert.assertEquals( Type.BOTTOM, TypeInteger.TOP.meet(TypeNil.NIL) );
+
+
         TypeStruct s1 = TypeStruct.make("s1", new Field[]{
                 Field.make("a", TypeInteger.BOT,-1, false),
                 Field.make("b", TypeInteger.BOT,-2, false) });
         TypeStruct s2 = TypeStruct.make("s2", new Field[]{
                 Field.make("a", TypeInteger.BOT,-3, false),
                 Field.make("b", TypeInteger.BOT,-4, false) });
-        Assert.assertEquals(s1, s1.glb());
+        Assert.assertEquals(s1.makeRO(), s1.glb());
         Assert.assertNotEquals(s1, s1.dual());
         Assert.assertEquals(s1.makeRO(), s1.dual().glb());
 
-        TypeMem m1 = TypeMem.make(1,TypeInteger.ZERO);
+        TypeMem m1 = TypeMem.make(1,TypeNil.NIL);
         TypeMem m2 = TypeMem.make(2,TypeInteger.U16);
-        TypeMem m3 = TypeMem.make(3,TypeFloat.BOT);
+        TypeMem m3 = TypeMem.make(3,TypeFloat.F64);
         TypeMem m4 = TypeMem.make(4,TypeInteger.BOT);
 
         Assert.assertNotEquals(m1, m2);
@@ -32,12 +34,12 @@ public class TypeTest {
         Assert.assertNotEquals(m3, m4);
 
         Assert.assertEquals(TypeStruct.BOT, s1.meet(s2));
-        Assert.assertEquals(TypeMem.make(-1,TypeInteger.U16), m1.meet(m2));
-        Assert.assertEquals(TypeMem   .BOT, m2.meet(m3));
+        Assert.assertEquals(TypeMem   .BOT, m1.meet(m2));
+        Assert.assertEquals(TypeMem.make(0,Type.BOTTOM), m1.meet(m3));
         Assert.assertEquals(TypeMem   .BOT, m3.meet(m4));
 
-        Assert.assertEquals(TypeMem.make(1,TypeInteger.BOT), m1.glb());
-        Assert.assertEquals(TypeMem.make(1,TypeInteger.ZERO), m1.dual());
+        Assert.assertEquals(TypeMem.make(1,Type.BOTTOM), m1.glb());
+        Assert.assertEquals(TypeMem.make(1,Type.XNIL), m1.dual());
         Assert.assertEquals(m4.dual(), m4.glb().dual());
 
         TypeMemPtr ptr1 = TypeMemPtr.make(s1);
@@ -45,34 +47,34 @@ public class TypeTest {
         TypeMemPtr ptr2 = TypeMemPtr.make(s2);
         Assert.assertEquals(s2, ptr2._obj);
 
-        TypeMemPtr ptr1nil = TypeMemPtr.make(s1, true);
+        TypeMemPtr ptr1nil = TypeMemPtr.makeNullable(s1);
         Assert.assertEquals(s1, ptr1nil._obj);
-        Assert.assertTrue(ptr1nil._nil);
-        Assert.assertFalse(ptr1nil._obj==null);
-        TypeMemPtr ptr2nil = TypeMemPtr.make(s2, true);
+        Assert.assertTrue( ptr1nil.nullable() );
+        Assert.assertNotNull( ptr1nil._obj );
+        TypeMemPtr ptr2nil = TypeMemPtr.makeNullable( s2);
         Assert.assertEquals(s2, ptr2nil._obj);
 
         Assert.assertNotEquals(ptr1, ptr2);
         Assert.assertNotEquals(ptr1, ptr1.glb());
-        Assert.assertEquals(ptr1nil, ptr1.glb());
+        Assert.assertEquals(ptr1nil.makeRO(), ptr1.glb());
 
         Assert.assertEquals(ptr1, ptr1.dual().dual());
         Assert.assertEquals(ptr1.glb().makeRO(), ptr1.dual().glb());
-        Assert.assertEquals(TypeMemPtr.make(TypeStruct.BOT,true), ptr1.meet(ptr2nil));
-        Assert.assertEquals(ptr1.glb(), ptr1.meet(TypeMemPtr.NULLPTR));
+        Assert.assertEquals(TypeMemPtr.makeNullable(TypeStruct.BOT), ptr1.meet(ptr2nil));
+        Assert.assertEquals(ptr1.glb(), ptr1.meet(TypeNil.NIL).makeRO());
 
         TypeMemPtr TOP = TypeMemPtr.TOP;
-        TypeMemPtr BOT = TypeMemPtr.make(TypeStruct.BOT,true );
-        TypeMemPtr PTR = TypeMemPtr.make(TypeStruct.BOT,false);
-        TypeMemPtr NULL = TypeMemPtr.NULLPTR;
+        TypeMemPtr BOT = TypeMemPtr.makeNullable(TypeStruct.BOT);
+        TypeMemPtr PTR = TypeMemPtr.make(TypeStruct.BOT);
+        Type NULL = TypeNil.NIL;
         Type PTR_meet_NULL = NULL.meet(PTR);
         Assert.assertEquals(BOT, PTR_meet_NULL);
         Type ptr1_meet_ptr2 = ptr1.meet(ptr2);
         Assert.assertEquals(PTR, ptr1_meet_ptr2);
         Type NULL_join_ptr1 = NULL.join(ptr1);
-        Assert.assertEquals(TOP, NULL_join_ptr1);
+        Assert.assertEquals(TypePtr.XNPTR, NULL_join_ptr1);
         Type NULL_join_PTR = PTR.join(NULL);
-        Assert.assertEquals(TOP, NULL_join_PTR);
+        Assert.assertEquals(TypePtr.XNPTR, NULL_join_PTR);
         Type ptr1_dual = ptr1.dual();
         Type nullableptr1_dual = ptr1nil.dual();
     }
@@ -153,5 +155,4 @@ public class TypeTest {
         assertSame(TypeStruct.S1,d1);
     }
 
-
 }
diff --git a/src/test/java/com/seaofnodes/simple/evaluator/Evaluator.java b/src/test/java/com/seaofnodes/simple/evaluator/Evaluator.java
index 72f84fa2..92b424df 100644
--- a/src/test/java/com/seaofnodes/simple/evaluator/Evaluator.java
+++ b/src/test/java/com/seaofnodes/simple/evaluator/Evaluator.java
@@ -4,8 +4,6 @@ import com.seaofnodes.simple.Utils;
 import com.seaofnodes.simple.node.*;
 import com.seaofnodes.simple.type.*;
 
-import java.lang.invoke.MethodHandle;
-import java.lang.invoke.MethodHandles;
 import java.util.*;
 
 public class Evaluator {
@@ -263,14 +261,14 @@ public class Evaluator {
     private double vald(Node node) {
         var v = val(node);
         if (v instanceof Number n) return n.doubleValue();
+        if( v == null ) return 0;
         throw new AssertionError("Not a double " + v);
     }
 
     private Object cons(ConstantNode cons) {
         var type = cons.compute();
-        if (type instanceof TypeInteger i) return i.value();
+        if (type instanceof TypeInteger i) return i.isConstant() ? i.value() : Integer.MAX_VALUE;
         if (type instanceof TypeFloat i) return i.value();
-        assert type instanceof TypeMemPtr;
         return null;
     }
 
@@ -307,8 +305,9 @@ public class Evaluator {
             case NewNode      alloc -> alloc(alloc);
             case CProjNode    cproj -> ((Object[])val(cproj.ctrl()))[cproj._idx];
             case ProjNode     proj  -> ((Object[])val( proj.in(0) ))[ proj._idx];
-            case ScopeMinNode mem   -> null;
+            case MemMergeNode mem   -> null;
             case ReadOnlyNode ro    -> val(ro.in(1));
+            case CallNode     call  -> Utils.TODO(); // should not reach here, go the IfNode route
             default                 -> throw new AssertionError("Unexpected node " + node);
         };
     }
@@ -328,31 +327,33 @@ public class Evaluator {
             for(; i<block.nodes().length;i++) values[block.nodes()[i]._nid] = exec(block.nodes()[i]);
             i=0;
             switch (block.exit()) {
-                case null:
-                    return Status.FALLTHROUGH;
-                case ReturnNode ret:
-                    return val(ret.in(1));
-                case IfNode ifn:
-                    block = block.next()[isTrue(val(ifn.in(1))) ? 0 : 1];
-                    if (block == null) return Status.FALLTHROUGH;
-                    break;
-                case RegionNode region:
-                    if (loops-- <= 0) return Status.TIMEOUT;
-                    int exit = block.exitId();
-                    assert exit > 0 && region.nIns() > exit;
-                    block = block.next()[0];
-                    assert block != null;
-                    for (; i < block.nodes().length; i++) {
-                        if (!(block.nodes()[i] instanceof PhiNode)) break;
-                        phiCache.add(val(block.nodes()[i].in(exit)));
-                    }
-                    for (i=0; i<phiCache.size(); i++) {
-                        values[block.nodes()[i]._nid] = phiCache.get(i);
-                    }
-                    phiCache.clear();
-                    break;
-                default:
-                    throw Utils.TODO("Unexpected control node " + block.exit());
+            case null:
+                return Status.FALLTHROUGH;
+            case ReturnNode ret :  return val(ret .expr());
+            case IfNode ifn:
+                block = block.next()[isTrue(val(ifn.in(1))) ? 0 : 1];
+                if (block == null) return Status.FALLTHROUGH;
+                break;
+            case RegionNode region:
+                if (loops-- <= 0) return Status.TIMEOUT;
+                int exit = block.exitId();
+                assert exit > 0 && region.nIns() > exit;
+                block = block.next()[0];
+                assert block != null;
+                for (; i < block.nodes().length; i++) {
+                    if (!(block.nodes()[i] instanceof PhiNode phi)) break;
+                    var val = region instanceof FunNode fun && "main".equals(fun.sig()._name) && ((ParmNode)phi)._idx==2 && exit==1
+                            ? parameter
+                            : val(phi.in(exit));
+                    phiCache.add(val);
+                }
+                for (i=0; i<phiCache.size(); i++) {
+                    values[block.nodes()[i]._nid] = phiCache.get(i);
+                }
+                phiCache.clear();
+                break;
+            default:
+                throw Utils.TODO("Unexpected control node " + block.exit());
             }
         }
     }
diff --git a/src/test/java/com/seaofnodes/simple/evaluator/Scheduler.java b/src/test/java/com/seaofnodes/simple/evaluator/Scheduler.java
index 06169e2c..52d8f3e3 100644
--- a/src/test/java/com/seaofnodes/simple/evaluator/Scheduler.java
+++ b/src/test/java/com/seaofnodes/simple/evaluator/Scheduler.java
@@ -87,6 +87,9 @@ public class Scheduler {
             this.entry = entry;
             this.prev = prev;
         }
+        BasicBlock(Node entry, BasicBlock prev) {
+            this(entry,prev.depth+1,prev);
+        }
 
     }
 
@@ -358,35 +361,29 @@ public class Scheduler {
         var queue = new Stack<NodeData>();
         var phiQueue = new Stack<NodeData>();
         queue.push(d(start));
-        int depth = 0;
         while (!queue.isEmpty()) {
             var data = queue.pop();
             var node = data.node;
             assert node instanceof CFGNode;
-            BasicBlock block;
-            switch (node) {
-                case StartNode s:
-                    block = new BasicBlock(s, depth++);
-                    break;
-                case LoopNode l:
-                    block = new BasicBlock(l, depth++, d(l.in(1)).block);
-                    break;
-                case RegionNode r:
+            BasicBlock block = switch (node) {
+            case StartNode s -> new BasicBlock(s, 0);
+            case LoopNode l -> new BasicBlock(l, d(l.in(1)).block);
+            case RegionNode r -> {
                     var prev = new ArrayList<BasicBlock>();
+                    int depth = 0;
                     for(int i=1; i<r.nIns(); i++) {
-                        od(r.in(i)).ifPresent(d->prev.add(d.block));
+                        if( !od(r.in(i)).isPresent() ) continue;
+                        BasicBlock bb = d(r.in(i)).block;
+                        prev.add(bb);
+                        depth = Math.max(depth,bb.depth);
                     }
-                    block = new BasicBlock(r, depth++, prev.toArray(BasicBlock[]::new));
-                    break;
-                case IfNode i:
-                    block = d(i.in(0)).block;
-                    break;
-                case ReturnNode r:
-                    block = d(r.in(0)).block;
-                    break;
-                default:
-                    block = new BasicBlock(node, depth++, d(node.in(0)).block);
+                    yield new BasicBlock(r, depth+1, prev.toArray(BasicBlock[]::new));
             }
+            case IfNode i -> d(i.in(0)).block;
+            case ReturnNode ret -> d(ret .in(0)).block;
+            case CallNode call -> throw Utils.TODO();
+            default -> new BasicBlock(node, d(node.in(0)).block);
+            };
             data.block = block;
             if (node instanceof RegionNode r) {
                 // Regions might have phis which need to be scheduled.
@@ -401,10 +398,17 @@ public class Scheduler {
                     }
                 }
             }
-            if (!(node instanceof ReturnNode))
+            if( node instanceof FunNode fun ) {
+                // Cannot find CFG user from fun via a naive search, because always find
+                // Return but Return is not always the one CFG user.
+                CFGNode n = fun.uctrl();
+                assert isCFGNodeReady(n) && d(n).block==null;
+                queue.push(d(n));
+            } else if( !(node instanceof ReturnNode) ) {
                 for (Node n : node._outputs)
                     if(n instanceof CFGNode && isCFGNodeReady(n) && d(n).block == null)
                         queue.push(d(n));
+            }
             var b = block;
             for(var in:data.node._inputs) od(in).ifPresent(d->update(d, b));
         }
@@ -449,7 +453,7 @@ public class Scheduler {
             var data = cfgQueue.pop();
             node = data.node;
             assert node instanceof CFGNode;
-            if (!(node instanceof ReturnNode)) {
+            if (!(node instanceof ReturnNode) ) {
                 for (var out : node._outputs) if (out!=null && out instanceof CFGNode && isNotXCtrl(out)) markAlive(cfgQueue, out, true);
             }
             for (var in : node._inputs) if(in!=null && !(in instanceof CFGNode) && isNotXCtrl(in)) markAlive(dataQueue, in, false);
@@ -499,15 +503,18 @@ public class Scheduler {
     /**
      * Find the CFG output of a node
      * @param node The node
-     * @return THe CFG output of the node.
+     * @return The CFG output of the node.
      */
-    private static Node findSingleCFGOut(Node node) {
+    private static CFGNode findSingleCFGOut(Node node) {
         if (node instanceof StartNode) {
-            for(var n:node._outputs) if (n instanceof CProjNode p && p._idx==0) return p;
+            for(var n:node._outputs)
+                if (n instanceof FunNode fun && "main".equals(fun.sig()._name) )
+                   return fun;
             return null;
         }
+        if( node instanceof FunNode fun ) return fun.uctrl();
         assert node._outputs.stream().filter(x -> x instanceof CFGNode).limit(2).count()<=1;
-        for(var n:node._outputs) if(n instanceof CFGNode) return n;
+        for(var n:node._outputs) if(n instanceof CFGNode cfg) return cfg;
         return null;
     }
 
@@ -561,7 +568,7 @@ public class Scheduler {
                 case null -> new Block(arr, null, -1, new Block[0]);
                 case IfNode i -> new Block(arr, i, -1, new Block[2]);
                 case RegionNode r -> new Block(arr, r, r._inputs.find(prev), new Block[1]);
-                case ReturnNode r -> new Block(arr, r, -1, new Block[0]);
+                case ReturnNode r -> new Block(arr, r   , -1, new Block[0]);
                 default -> throw new AssertionError("Unexpected block exit node");
             });
         }
diff --git a/src/test/java/com/seaofnodes/simple/fuzzer/Fuzzer.java b/src/test/java/com/seaofnodes/simple/fuzzer/Fuzzer.java
index 51e39cd0..f57a0031 100644
--- a/src/test/java/com/seaofnodes/simple/fuzzer/Fuzzer.java
+++ b/src/test/java/com/seaofnodes/simple/fuzzer/Fuzzer.java
@@ -1,10 +1,9 @@
 package com.seaofnodes.simple.fuzzer;
 
 import com.seaofnodes.simple.Parser;
-import com.seaofnodes.simple.evaluator.Evaluator;
+import com.seaofnodes.simple.Eval2;
+import com.seaofnodes.simple.CodeGen;
 import com.seaofnodes.simple.node.Node;
-import com.seaofnodes.simple.node.StopNode;
-
 import java.util.ArrayList;
 import java.util.Objects;
 import java.util.Random;
@@ -46,8 +45,8 @@ public class Fuzzer {
         e.printStackTrace(System.out);
         System.out.println("========== Seed ==========");
         System.out.println(seed);
-        System.out.println("========== Code ===========");
-        System.out.println(script);
+        //System.out.println("========== Code ===========");
+        //System.out.println(script);
         System.out.println("========= Reduced =========");
         System.out.println(Reducer.reduce(script, e, reproducer));
         System.out.println("===========================");
@@ -56,13 +55,6 @@ public class Fuzzer {
 
     private static boolean neq(Object a, Object b) {
         if (Objects.equals(a, b)) return false;
-        if (a instanceof Evaluator.Obj ea && b instanceof Evaluator.Obj eb) {
-            if (ea.struct() != eb.struct()) return true;
-            for(int i=0;i<ea.fields().length;i++) {
-                if (neq(ea.fields()[i], eb.fields()[i])) return true;
-            }
-            return false;
-        }
         return true;
     }
 
@@ -72,11 +64,11 @@ public class Fuzzer {
      * @param e2 Evaluator for the second graph
      * @param in The input value to both graphs to test for an equal output
      */
-    private static void checkGraphs(Evaluator e1, Evaluator e2, long in) {
-        var r1 = e1.evaluate(in, EVAL_TIMEOUT);
-        var r2 = e2.evaluate(in, EVAL_TIMEOUT);
-        if (r1 == Evaluator.Status.TIMEOUT || r2 == Evaluator.Status.TIMEOUT) return;
-        if (neq(r1, r2))
+    private static void checkGraphs(CodeGen code1, CodeGen code2, long in) {
+        var r1 = Eval2.eval(code1, in, EVAL_TIMEOUT);
+        var r2 = Eval2.eval(code2, in, EVAL_TIMEOUT);
+        if( r1 == null || r2 == null ) return; // Timeout test invalid
+        if( neq(r1, r2) )
             throw new RuntimeException("Different calculations values " + r1 + " vs " + r2);
     }
 
@@ -88,27 +80,25 @@ public class Fuzzer {
      * @param valid If the script is definitely valid. If not some exceptions may be suppressed.
      */
     private static void runCheck(String script, boolean valid) {
-        StopNode stop1;
+        CodeGen code1;
         try {
-            stop1 = FuzzerUtils.parse(script, false);
+            code1 = FuzzerUtils.parse(script, false);
         } catch (RuntimeException e1) {
             try {
                 FuzzerUtils.parse(script, true);
             } catch (RuntimeException e2) {
                 if (FuzzerUtils.isExceptionFromSameCause(e1, e2)) {
-                    if (!valid || e1.getClass() == RuntimeException.class) return;
+                    if (!valid || e1.getClass() == Parser.ParseException.class) return;
                 } else {
                     e1.addSuppressed(e2);
                 }
             }
             throw e1;
         }
-        var stop2 = FuzzerUtils.parse(script, true);
-        var e1 = new Evaluator(stop1);
-        var e2 = new Evaluator(stop2);
-        checkGraphs(e1, e2, 0);
-        checkGraphs(e1, e2, 1);
-        checkGraphs(e1, e2, 10);
+        CodeGen code2 = FuzzerUtils.parse(script, true);
+        checkGraphs(code1, code2, 0);
+        checkGraphs(code1, code2, 1);
+        checkGraphs(code1, code2, 10);
     }
 
     /**
@@ -133,9 +123,9 @@ public class Fuzzer {
         var sb = new StringBuilder();
         new ScriptGenerator(rand, sb, true).genProgram();
         try {
-            var parser = new Parser(sb.toString());
+            var code = new CodeGen(sb.toString());
 
-            var stop = parser.parse();
+            code.parse();
             int parse_peeps= Node.ITER_CNT;
             int parse_nops = Node.ITER_NOP_CNT;
             double parse_nop_ratio = (double)parse_nops/parse_peeps;
@@ -144,7 +134,7 @@ public class Fuzzer {
 
             double parse_peeps_per_node = (double)parse_peeps/nids;
 
-            stop.iterate();
+            code.opto();
             int iter_peeps= Node.ITER_CNT;
             int iter_nops = Node.ITER_NOP_CNT;
             double iter_nop_ratio = (double)iter_nops/iter_peeps;
diff --git a/src/test/java/com/seaofnodes/simple/fuzzer/FuzzerUtils.java b/src/test/java/com/seaofnodes/simple/fuzzer/FuzzerUtils.java
index 18ef069a..62a149a8 100644
--- a/src/test/java/com/seaofnodes/simple/fuzzer/FuzzerUtils.java
+++ b/src/test/java/com/seaofnodes/simple/fuzzer/FuzzerUtils.java
@@ -1,10 +1,9 @@
 package com.seaofnodes.simple.fuzzer;
 
+import com.seaofnodes.simple.CodeGen;
 import com.seaofnodes.simple.IterPeeps;
-import com.seaofnodes.simple.Parser;
 import com.seaofnodes.simple.node.Node;
 import com.seaofnodes.simple.node.StopNode;
-
 import java.io.OutputStream;
 import java.io.PrintStream;
 import java.lang.invoke.MethodHandle;
@@ -115,7 +114,7 @@ class FuzzerUtils {
     /**
      * Parse script with peepholes enabled or disabled
      */
-    public static StopNode parse(String script, boolean runPeeps) {
+    public static CodeGen parse(String script, boolean runPeeps) {
         var err = System.err;
         var out = System.out;
         try {
@@ -126,10 +125,8 @@ class FuzzerUtils {
             } catch (Throwable e) {
                 throw rethrow(e);
             }
-            var parser = new Parser(script);
-            Node._disablePeephole = !runPeeps;
-            var stop = parser.parse();
-            return runPeeps ? stop.iterate() : stop;
+            var code = new CodeGen(script);
+            return code.parse(!runPeeps).opto().typeCheck().GCM().localSched();
         } finally {
             NodeWalkVisit.clear();
             System.setErr(err);
diff --git a/src/test/java/com/seaofnodes/simple/fuzzer/ScriptGenerator.java b/src/test/java/com/seaofnodes/simple/fuzzer/ScriptGenerator.java
index d3cbb0ee..86dbe66a 100644
--- a/src/test/java/com/seaofnodes/simple/fuzzer/ScriptGenerator.java
+++ b/src/test/java/com/seaofnodes/simple/fuzzer/ScriptGenerator.java
@@ -483,7 +483,7 @@ public class ScriptGenerator {
             fields[i] = new TypeStruct.Field(fieldName.toString(), type, struct);
         }
         indentation -= INDENTATION;
-        printIndentation().append("}");
+        printIndentation().append("};");
         struct.fields = fields;
         forwardStructs.remove(struct);
         structs.add(struct);
@@ -683,7 +683,8 @@ public class ScriptGenerator {
     public int genDecl() {
         var type = getType();
         var name = getVarName();
-        sb.append(generateInvalid() ? getRandomName() : type.name).append(" ").append(name);
+        // Always make them mutable
+        sb.append(generateInvalid() ? getRandomName() : type.name).append(" !").append(name);
         if (!(type instanceof TypeNullable) || random.nextBoolean()) {
             sb.append("=");
             genExpression(type, true);