Chapter 22: A Hello, World!

Co-authored-by: godalming123 <68993177+godalming123@users.noreply.github.com>
Co-authored-by: Tamás Hadházy <85063808+Hels15@users.noreply.github.com>
Co-authored-by: Hsiang-Ying Fu <66062782+fuhsnn@users.noreply.github.com>
Co-authored-by: fuhsnn <66062782+fuhsnn@users.noreply.github.com>
Co-authored-by: Symious <14933944+symious@users.noreply.github.com>
Co-authored-by: Jun Kawasaki <jun784@gmail.com>
Co-authored-by: Claude Opus 5 <noreply@anthropic.com>

55 files changed, 1187 insertions, 499 deletions

diff --git a/src/test/java/com/seaofnodes/simple/BrainFuckTest.java b/src/test/java/com/seaofnodes/simple/BrainFuckTest.java
index 97d33b70..9f626805 100644
--- a/src/test/java/com/seaofnodes/simple/BrainFuckTest.java
+++ b/src/test/java/com/seaofnodes/simple/BrainFuckTest.java
@@ -20,7 +20,7 @@ public class BrainFuckTest {
         String brain_fuck = "Hello World!\n";
         TestC.run("brain_fuck", brain_fuck, 40);
 
-        EvalRisc5 R5 = TestRisc5.build("brain_fuck", 0, 42, false);
+        EvalRisc5 R5 = TestRisc5.build("brain_fuck", 0, 28, false);
         int trap = R5.step(100000);
         assertEquals(0,trap);
         int ptr = (int)R5.regs[riscv.A0];
@@ -28,7 +28,7 @@ public class BrainFuckTest {
         for( int i=0; i<brain_fuck.length(); i++ )
             assertEquals(brain_fuck.charAt(i), R5.ld1z(ptr+4+i));
 
-        EvalArm64 A5 = TestArm64.build("brain_fuck", 0, 34, false);
+        EvalArm64 A5 = TestArm64.build("brain_fuck", 0, 28, false);
         int trap_arm = A5.step(100000);
         assertEquals(0,trap_arm);
         assertEquals(0,trap);
diff --git a/src/test/java/com/seaofnodes/simple/Chapter01Test.java b/src/test/java/com/seaofnodes/simple/Chapter01Test.java
index cddbdfcf..ac9adacc 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter01Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter01Test.java
@@ -25,9 +25,9 @@ public class Chapter01Test {
     public void testZero() {
         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);
+        Node use = code.expr();
+        if( use instanceof ConstantNode con && con._type instanceof TypeInteger )
+            assertEquals(TypeInteger.constant(0),con._type);
     }
 
     @Test
diff --git a/src/test/java/com/seaofnodes/simple/Chapter05Test.java b/src/test/java/com/seaofnodes/simple/Chapter05Test.java
index c809f72f..8168594a 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter05Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter05Test.java
@@ -20,7 +20,7 @@ else {
 }
 return a;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Region,(arg+2),(arg-3));", code.print());
     }
 
@@ -36,7 +36,7 @@ if (arg == 1) {
 }
 return c;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Region,4,3);", code.print());
     }
 
@@ -64,7 +64,7 @@ if( arg==1 )
 else
     b=a+1;
 return a+b;""");
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return ((arg<<1)+Phi(Region,2,3));", code.print());
     }
 
@@ -79,7 +79,7 @@ if( arg==1 )
 else
     a=b+1;
 return a+b;""");
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return ((Phi(Region,(arg<<1),arg)+arg)+Phi(Region,4,5));", code.print());
     }
 
@@ -99,7 +99,7 @@ else
     a=5;
 return a;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Region,3,5,2,4);", code.print());
     }
 
@@ -115,7 +115,7 @@ if( arg==0 )
     b=2;
 return arg+a+b;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return ((arg+Phi(Region,1,0))+Phi(Region,2,0));", code.print());
     }
 
@@ -130,7 +130,7 @@ if( arg==1 )
 }
 return a;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return (arg==Phi(Region,3,2));", code.print());
     }
 
@@ -145,7 +145,7 @@ else
     a=3;
 return a;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 3;", code.print());
     }
 
diff --git a/src/test/java/com/seaofnodes/simple/Chapter06Test.java b/src/test/java/com/seaofnodes/simple/Chapter06Test.java
index 2c97b9c2..ad3597f2 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter06Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter06Test.java
@@ -15,7 +15,7 @@ public class Chapter06Test {
 if( true ) return 2;
 return 1;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 2;", code.print());
         assertTrue(code.ctrl() instanceof FunNode);
     }
@@ -29,7 +29,7 @@ if (arg)
     a = 2;
 return (arg < a) < 3; // Because (arg < a) is a bool/uint1/[0-1], its always less than 3
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 1;", code.print());
     }
 
@@ -44,7 +44,7 @@ else
   a=3;
 return a;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 2;", code.print());
         assertTrue(code.ctrl() instanceof FunNode);
     }
@@ -65,7 +65,7 @@ else
     b=5;
 return b;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Region,42,5);", code.print());
     }
 
@@ -84,7 +84,7 @@ if( arg==2 )
 else
     b=5;
 return b;""");
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Region,2,5);", code.print());
     }
 
@@ -104,7 +104,7 @@ else if( arg==3 )
 else
     a=5;
 return a;
-""", TypeInteger.constant(2), 123L).parse().iter();
+""", TypeInteger.constant(2), 123L).parse().iter().finalizeIR();
         assertEquals("return 5;", code.print());
     }
 
@@ -124,7 +124,7 @@ else if( arg==3 )
 else
     a=5;
 return a;
-""", TypeInteger.constant(1), 123L).parse().iter();
+""", TypeInteger.constant(1), 123L).parse().iter().finalizeIR();
         assertEquals("return 3;", code.print());
     }
 
@@ -144,7 +144,7 @@ else
     a=5;
 return a;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Region,3,5,4);", code.print());
     }
 
@@ -165,7 +165,7 @@ else
     a=5;
 return a;
 """, TypeInteger.constant(1), 123L);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 3;", code.print());
     }
 
@@ -186,7 +186,7 @@ else
     a=5;
 return a;
 """, TypeInteger.constant(3), 123L);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 4;", code.print());
     }
 
@@ -202,7 +202,7 @@ if( arg ) {
 }
 return a+b;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Region,4,1);", code.print());
     }
 
@@ -221,7 +221,7 @@ if( arg ) {
 }
 return a+b;
 """, TypeInteger.constant(1), 123L);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 4;", code.print());
     }
 
@@ -239,7 +239,7 @@ if( arg ) {
 }
 return a+b;
 """, TypeInteger.constant(0), 123L);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 1;", code.print());
     }
 
@@ -257,7 +257,7 @@ if( arg ) {
 }
 return a+b+c;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Region,6,1,5);", code.print());
     }
 
@@ -278,7 +278,7 @@ if( arg ) {
 }
 return a+b+c;
 """, TypeInteger.constant(1), 123L);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 6;", code.print());
     }
 
@@ -298,7 +298,7 @@ if( arg ) {
 }
 return a+b+c;
 """, TypeInteger.constant(2), 123L);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         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 b0526eb1..0ebc427c 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter07Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter07Test.java
@@ -34,7 +34,7 @@ if(arg){}else{
 }
 return a;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Region,1,Phi(Loop,1,(Phi_a+1)));", code.print());
     }
 
@@ -54,7 +54,7 @@ while(i < arg) {
 }
 return sum;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Loop,0,Phi(Loop,Phi_sum,(Phi_sum+Phi(Loop,0,(Phi_j+1)))));", code.print());
     }
 
@@ -89,7 +89,7 @@ while(a < 10) {
 }
 return b;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Loop,2,(Phi(Region,Phi_b,4)+1));", code.print());
         assertTrue(code.ctrl() instanceof CProjNode);
     }
@@ -122,7 +122,7 @@ while(a < 10) {
 }
 return a;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Loop,1,(Phi_a+3));", code.print());
         assertTrue(code.ctrl() instanceof CProjNode);
     }
@@ -148,7 +148,7 @@ int a = 1;
 while(arg) a = 2;
 return a;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Loop,1,2);", code.print());
         assertTrue(code.ctrl() instanceof CProjNode);
     }
@@ -180,7 +180,7 @@ while(a < 10) {
 }
 return a;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Loop,1,(Phi_a+3));", code.print());
         assertTrue(code.ctrl() instanceof CProjNode);
     }
@@ -214,7 +214,7 @@ while(a < 10) {
 }
 return a;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         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 487a2c7b..543b91d1 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter08Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter08Test.java
@@ -22,7 +22,7 @@ while(arg < 10) {
 }
 return arg;
                 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Region,(Phi(Loop,arg,Add)+1),Add,Phi_arg);", code.print());
         assertTrue(code.ctrl() instanceof RegionNode);
         Assert.assertEquals( "5", Eval2.eval(code, 1));
@@ -45,7 +45,7 @@ while(arg < 10) {
 }
 return a;
                 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Loop,1,Phi(Region,Phi_a,(Phi_a+1),Phi_a));", code.print());
         assertTrue(code.ctrl() instanceof CProjNode);
     }
@@ -64,7 +64,7 @@ while(arg < 10) {
 }
 return arg;
                 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Region,Phi(Loop,arg,(Phi_arg+1)),Add);", code.print());
         assertTrue(code.ctrl() instanceof RegionNode);
     }
@@ -80,7 +80,7 @@ while(arg < 10) {
 }
 return arg;
                 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Region,Phi(Loop,arg,(Phi_arg+1)),Add);", code.print());
         assertTrue(code.ctrl() instanceof RegionNode);
     }
@@ -99,7 +99,7 @@ while(arg < 10) {
 }
 return arg;
                 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Loop,arg,(Phi_arg+1));", code.print());
         assertTrue(code.ctrl() instanceof CProjNode);
     }
@@ -116,7 +116,7 @@ while(arg < 10) {
 }
 return arg;
                 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Loop,arg,(Phi_arg+1));", code.print());
         assertTrue(code.ctrl() instanceof CProjNode);
     }
@@ -132,14 +132,14 @@ while( arg < 10 ) {
 }
 return arg;
                 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return arg;", code.print());
     }
 
     @Test
     public void testRegress2() {
         CodeGen code = new CodeGen("if(1) return 0;  else while(arg>- -arg) arg=arg+1; return 0;");
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 0;", code.print());
     }
 
@@ -167,7 +167,7 @@ while(arg < 10) {
 }
 return arg;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return arg;", code.print());
     }
 
@@ -184,7 +184,7 @@ while(arg < 10) {
 }
 return a;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Region,Phi(Loop,1,(Phi_a+1)),Add);", code.print());
         assertTrue(code.ctrl() instanceof RegionNode);
     }
@@ -200,7 +200,7 @@ while(1) {
 }
 return a;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         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 0a3049e6..df590448 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter09Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter09Test.java
@@ -24,7 +24,7 @@ while(v0) {
 }
 return 0;
                 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
     }
 
     @Test
@@ -40,7 +40,7 @@ else {
 }
 return x;
                 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Region,(arg<<1),(Shl+1));", code.print());
         Assert.assertEquals( "2", Eval2.eval(code,  1));
         Assert.assertEquals("23", Eval2.eval(code, 11));
@@ -49,7 +49,7 @@ return x;
     @Test
     public void testGVN2() {
         CodeGen code = new CodeGen("return arg*arg-arg*arg;");
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 0;", code.print());
         Assert.assertEquals("0", Eval2.eval(code,  1, 1));
     }
@@ -63,7 +63,7 @@ while (arg < 10) {
 }
 return arg;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Loop,arg,(Phi_arg+2));", code.print());
         Assert.assertEquals("11", Eval2.eval(code,  1));
     }
@@ -80,7 +80,7 @@ while (arg < 10) {
 }
 return arg;
                 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Loop,arg,(Phi_arg+4));", code.print());
         Assert.assertEquals("13", Eval2.eval(code,  1));
     }
@@ -109,7 +109,7 @@ while (arg) {
 }
 return arg;
                 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 0;", code.print());
     }
 
@@ -127,15 +127,15 @@ while(v1+arg) {
     v1=v2;
 }
                 """);
-        code.parse().iter();
-        assertEquals("return 0;", code.print());
+        code.parse().iter().finalizeIR();
+        assertEquals("Stop[ ]", code.print()); // No explicit return: omit default main.
     }
 
     @Test
     public void testWhile0() {
-        CodeGen code = new CodeGen("while(0) continue; if(0) arg=0;");
-        code.parse().iter();
-        assertEquals("return 0;", code.print());
+        CodeGen code = new CodeGen("while(0) continue; if(0) arg=0; return arg;");
+        code.parse().iter().finalizeIR();
+        assertEquals("return arg;", code.print());
     }
 
     @Test
@@ -145,8 +145,9 @@ if(0) while(0) {
     int arg=arg;
     while(0) {}
 }
+return 0;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 0;", code.print());
     }
 
@@ -154,14 +155,14 @@ if(0) while(0) {
     @Test
     public void testPrecedence() {
         CodeGen code = new CodeGen("return 3-1+2;");
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 4;", code.print());
     }
 
     @Test
     public void testSwap2() {
         CodeGen code = new CodeGen("return 1+(1+1);");
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 3;", code.print());
     }
 
@@ -179,7 +180,7 @@ while(arg) {
 }
 return a;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Loop,0,(-(Phi_a+3)));", code.print());
     }
 
@@ -193,7 +194,7 @@ arg=0;
 int v0=0!=0<-0;
 return -0+0+0;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Top;", code.print());
     }
 
@@ -201,15 +202,15 @@ return -0+0+0;
     @Test
     public void testFuzz2() {
         CodeGen code = new CodeGen("return 0+-0;");
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 0;", code.print());
     }
 
     @Test
     public void testFuzz3() {
         CodeGen code = new CodeGen("int v0=0; while(0==69) while(v0) return 0;");
-        code.parse().iter();
-        assertEquals("return 0;", code.print());
+        code.parse().iter().finalizeIR();
+        assertEquals("Stop[ ]", code.print()); // The only return is unreachable.
     }
 
     @Test
@@ -220,7 +221,7 @@ while(1) {
     if(1<0) while(arg==-0) arg=arg-arg;
 }
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Top;", code.print());
     }
 
@@ -242,7 +243,7 @@ while(1) {
 }
 return 0!=0;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Top;", code.print());
     }
 
@@ -254,8 +255,8 @@ int v0=0;
 while(0==1) while(v0)
         v0=1+v0;
 """);
-        code.parse().iter();
-        assertEquals("return 0;", code.print());
+        code.parse().iter().finalizeIR();
+        assertEquals("Stop[ ]", code.print());
     }
 
     @Test
@@ -270,14 +271,14 @@ while(1)
         v1=1;
 return v1+v0;
                                    """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Top;", code.print());
     }
 
     @Test
     public void testFuzz8() {
         CodeGen code = new CodeGen("while(arg) arg = arg - 1;  return arg;");
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 0;", code.print());
     }
 
diff --git a/src/test/java/com/seaofnodes/simple/Chapter10Test.java b/src/test/java/com/seaofnodes/simple/Chapter10Test.java
index 3e01458b..5fbae210 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter10Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter10Test.java
@@ -32,7 +32,7 @@ public class Chapter10Test {
             "if(1) return new S; else return 0;"
         } ) {
             String src = "struct S { int x; }; " + body;
-            var code = new CodeGen(src).parse().iter().typeCheck();
+            var code = new CodeGen(src).driver(CodeGen.Phase.TypeCheck);
             org.junit.Assert.assertTrue(body,
                 code.expr()._type instanceof com.seaofnodes.simple.type.TypeMemPtr);
         }
@@ -57,7 +57,7 @@ public class Chapter10Test {
             "if (!!!p) return -1; return p.x;",
             "int b = !!p; if (b) return p.x + b - 1; return -1;"
         } ) {
-            CodeGen code = new CodeGen(NULLABLE_POINT_SOURCE+body).parse().iter().typeCheck();
+            CodeGen code = new CodeGen(NULLABLE_POINT_SOURCE+body).driver(CodeGen.Phase.TypeCheck);
             assertEquals(body,"-1",Eval2.eval(code,0));
             assertEquals(body,"42",Eval2.eval(code,1));
         }
@@ -72,7 +72,7 @@ public class Chapter10Test {
             "if (!!p) { int x = p.x; } return p.x;"
         } ) {
             try {
-                new CodeGen(NULLABLE_POINT_SOURCE+body).parse().iter().typeCheck();
+                new CodeGen(NULLABLE_POINT_SOURCE+body).driver(CodeGen.Phase.TypeCheck);
                 fail(body);
             } catch( RuntimeException e ) {
                 // Known null is rejected during parsing in these chapters.
@@ -104,7 +104,7 @@ if( (arg/13)==0 ) {
 int r = g+h;
 return p-r;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 0;", code.print());
     }
 
@@ -124,7 +124,7 @@ bar.a = 1;
 bar.a = 2;
 return bar.a;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 2;", code.print());
     }
 
@@ -140,7 +140,7 @@ else
     v.y = 3;
 return v;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Vector2D;", code.print());
     }
 
@@ -178,7 +178,7 @@ while (arg) {
 }
 return bar.a;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Loop,0,(Phi_a+2));", code.print());
     }
 
@@ -191,7 +191,7 @@ if (arg) bar = null;
 bar.a = 1;
 return bar.a;
 """);
-        try { code.parse().iter(); fail(); }
+        try { code.parse().iter().finalizeIR(); fail(); }
         catch( Exception e ) { assertEquals("Type null is not of declared type *Bar",e.getMessage()); }
     }
 
@@ -204,7 +204,7 @@ if (arg) bar = new Bar;
 bar.a = 1;
 return bar.a;
 """);
-        try { code.parse().iter().typeCheck(); fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
         catch( Exception e ) { assertEquals("Might be null accessing 'a'",e.getMessage()); }
     }
 
@@ -230,7 +230,7 @@ if (arg) bar = null;
 if( bar ) bar.a = 1;
 return bar;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Region,null,Bar);", code.print());
     }
 
@@ -246,7 +246,7 @@ if( !bar ) rez=4;
 else bar.a = 1;
 return rez;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Region,4,3);", code.print());
     }
 
@@ -263,7 +263,7 @@ while(arg) {
 }
 return ret;
 """);
-        try { code.parse().iter().typeCheck(); fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
         catch( Exception e ) {
             assertEquals("Might be null accessing 'v0'", e.getMessage()); }
     }
@@ -300,7 +300,7 @@ while( i.x < i.len ) {
 }
 return sum;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Loop,0,(Phi(Loop,0,(Phi_x+1))+Phi_sum));", code.print());
     }
 
@@ -319,7 +319,7 @@ while(arg) {
 }
 return ret;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Loop,s0,Phi(Region,s0,Phi_ret));", code.print());
     }
 
@@ -337,7 +337,7 @@ while(arg) {
 }
 return ret;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Loop,s0,Phi(Region,s0,Phi_ret));", code.print());
     }
 
@@ -354,7 +354,7 @@ while(arg < 10) {
 }
 return ret;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Loop,s0,Phi(Region,s0,Phi_ret));", code.print());
     }
 
@@ -380,8 +380,9 @@ if(0) {
         v0=v2;
     }
 }
+return 0;
    """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 0;", code.print());
     }
 
@@ -395,7 +396,7 @@ if(0) return 0;
 else return new s0;
 if(new s0.f0) return 0;
     """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return s0;", code.print());
     }
 
@@ -411,7 +412,7 @@ while(0<arg) {
 }
 return 0;
     """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
     }
 
     @Test
@@ -423,7 +424,7 @@ while(v0.f0) {}
 s0 v1 = v0;
 return v1;
     """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return (const)s0;", code.print());
     }
 
@@ -454,8 +455,9 @@ while(0) {}
             }
         }    }
 }
+return 0;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 0;", code.print());
     }
 
@@ -466,7 +468,7 @@ int v0=arg==0;
 while(v0) continue;
 return 0;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 0;", code.print());
     }
 
@@ -480,7 +482,7 @@ return 0;
             a.y = 55; b.y = 66;
             a.x = 33; b.x = 44;
             return before*100 + p.x;
-            """).parse().iter();
+            """).parse().iter().finalizeIR();
         StopNode stop = code._stop;
         assertEquals("1133",Eval2.eval(code,0));
         assertEquals("2244",Eval2.eval(code,1));
@@ -506,7 +508,7 @@ return 0;
             """;
 
     @Test public void testMemoryAcrossNestedLoops() {
-        var code = new CodeGen(NESTED_MEMORY).parse().iter();
+        var code = new CodeGen(NESTED_MEMORY).parse().iter().finalizeIR();
         StopNode stop = code._stop;
         for (int arg=0; arg<7; arg++) {
             assertEquals("S{x="+(5L+arg)+",y="+(7L+arg*(arg+1)-(arg>=2 ? 2 : 0))+
@@ -522,7 +524,7 @@ return 0;
             if (arg) { s.x = 11; s.z = 13; return s; }
             s.y = 17;
             return s;
-            """).parse().iter();
+            """).parse().iter().finalizeIR();
         StopNode stop = code._stop;
         for (int arg=0; arg<2; arg++) {
             assertEquals(arg==0 ? "S{x=3,y=17,z=7}" : "S{x=11,y=5,z=13}",Eval2.eval(code,arg));
@@ -539,7 +541,7 @@ return 0;
             int v;
             if (arg>1) v=p.x; else v=q.x;
             return v;
-            """).parse().iter();
+            """).parse().iter().finalizeIR();
         StopNode stop = code._stop;
         // The one-step safety check stops at the memory aggregate.
         assertEquals(2,countMemoryNodes(stop,LoadNode.class,new BitSet()));
@@ -554,7 +556,7 @@ return 0;
             !S !s = new S;
             if (arg) s.x=arg+1; else s.x=arg+2;
             return s;
-            """).parse().iter();
+            """).parse().iter().finalizeIR();
         StopNode stop = code._stop;
         // Keep each Store on its own branch.
         assertEquals(2,countMemoryNodes(stop,StoreNode.class,new BitSet()));
@@ -573,7 +575,7 @@ return 0;
             if (arg>1) { v=p.x; p.x=41; p.y=5; }
             else       { v=q.x; q.x=42; }
             return v;
-            """).parse().iter();
+            """).parse().iter().finalizeIR();
         StopNode stop = code._stop;
         assertEquals(2,countMemoryNodes(stop,LoadNode.class,new BitSet()));
         assertEquals("-1",Eval2.eval(code,-1));
diff --git a/src/test/java/com/seaofnodes/simple/Chapter11Test.java b/src/test/java/com/seaofnodes/simple/Chapter11Test.java
index a74f8540..a2a6aab4 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter11Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter11Test.java
@@ -13,7 +13,7 @@ public class Chapter11Test {
             s.x = 42;
             while (arg > 0) { s.y = s.y + arg; arg = arg - 1; }
             return s.x;
-            """).parse().iter();
+            """).parse().iter().finalizeIR();
         var stop = code._stop;
         assertEquals("return 42;",stop.toString());
         assertEquals("42",Eval2.eval(code,5));
@@ -32,7 +32,7 @@ public class Chapter11Test {
                 arg = arg - 1;
             }
             return a;
-            """).parse().iter();
+            """).parse().iter().finalizeIR();
         var stop = code._stop;
         int[] phis = {0};
         stop.walk(n -> {
@@ -54,7 +54,7 @@ public class Chapter11Test {
         // it. Keep both the worklist assertion and the final heap check.
         for (int seed : new int[]{0,97,123,456}) {
             var code = new CodeGen(Chapter10Test.NESTED_MEMORY,com.seaofnodes.simple.type.TypeInteger.BOT,seed).parse();
-            code.iter();
+            code.iter().finalizeIR();
             assertEquals("S{x=9,y=25,z=17}",Eval2.eval(code,4));
         }
     }
diff --git a/src/test/java/com/seaofnodes/simple/Chapter12Test.java b/src/test/java/com/seaofnodes/simple/Chapter12Test.java
index 324b2a12..e680af8c 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter12Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter12Test.java
@@ -14,7 +14,7 @@ public class Chapter12Test {
 """
 return 3.14;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 3.14;", code.print());
         assertEquals("3.14", Eval2.eval(code,  0));
     }
@@ -34,7 +34,7 @@ while( arg ) {
 }
 return head.next.i;
 """);
-        try { code.parse().iter().typeCheck(); fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
         catch( Exception e ) { assertEquals("Might be null accessing 'next'",e.getMessage()); }
     }
 
@@ -56,7 +56,7 @@ LLI? next = head.next;
 if( next==null ) return 1;
 return next.i;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Region,0,1,.i);", code.print());
         assertEquals("2", Eval2.eval(code,  3));
     }
@@ -75,7 +75,7 @@ i0.f = f0;
 f0.i = i0;
 return f0.i.f.i.i;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 17;", code.print());
     }
 
@@ -87,7 +87,7 @@ struct N { !N? !next; int i; };
 N n = new N;
 return n.next;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return null;", code.print());
     }
 
@@ -100,7 +100,7 @@ struct N { !M !next; int i; };
 N n = new N { next = new M; };
 return n.next;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return (const)M;", code.print());
     }
 
@@ -113,7 +113,7 @@ struct N { !M !next; int i; };
 N n = new N { next = null; }
 return n.next;
 """);
-        try { code.parse().iter(); fail(); }
+        try { code.parse().iter().finalizeIR(); fail(); }
         catch( Exception e ) { assertEquals("Type null is not of declared type *M",e.getMessage()); }
     }
 
@@ -126,21 +126,21 @@ struct N { !N? !next; int i; };
 n.i = 3.14;
 return n.i;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("3",Eval2.eval(code,0));
     }
 
     @Test
     public void testNullRef4() {
-        CodeGen code = new CodeGen("-null-5/null-5;");
-        try { code.parse().iter().typeCheck(); fail(); }
-        catch( Exception e ) { assertEquals("Cannot 'Add' null",e.getMessage()); }
+        CodeGen code = new CodeGen("return -null-5/null-5;");
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
+        catch( Exception e ) { assertEquals("Cannot '+' null",e.getMessage()); }
     }
 
     @Test public void testNullRef5() {
         CodeGen code = new CodeGen("return null+42;");
-        try { code.parse().iter().typeCheck(); fail(); }
-        catch( Exception e ) { assertEquals("Cannot 'Add' null",e.getMessage()); }
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
+        catch( Exception e ) { assertEquals("Cannot '+' null",e.getMessage()); }
     }
 
     @Test
@@ -148,8 +148,9 @@ return n.i;
         CodeGen code = new CodeGen(
 """
 struct S{};
+return 0;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 0;", code.print());
         assertEquals("0", Eval2.eval(code,  0));
     }
@@ -161,7 +162,7 @@ struct S{};
 struct S1 { !S2? !s; };
 return new S2;
 """);
-        try { code.parse().iter(); fail(); }
+        try { code.parse().iter().finalizeIR(); fail(); }
         catch( Exception e ) { assertEquals("Unknown struct type 'S2'",e.getMessage()); }
     }
 
@@ -173,7 +174,7 @@ struct S1 { !S2? !s; };
 struct S2 { int x; };
 return new S1.s=new S2;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return S2;", code.print());
     }
 
@@ -190,7 +191,7 @@ p2.pi.i = 2;
 if (arg) p1 = new P;
 return p1.pi.i + 1;
 """);
-        try { code.parse().iter().typeCheck();  fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck);  fail(); }
         catch( Exception e ) {  assertEquals("Might be null accessing 'i'",e.getMessage());  }
     }
 
diff --git a/src/test/java/com/seaofnodes/simple/Chapter13Test.java b/src/test/java/com/seaofnodes/simple/Chapter13Test.java
index 4e56b9de..4f699a3f 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter13Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter13Test.java
@@ -325,7 +325,7 @@ while( prime <= arg ) {
 }
 return primeCount;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Region,0,Phi(Loop,1,Phi(Region,Phi_primeCount,Phi_primeCount,(Phi_primeCount+1))));", code.print());
         assertEquals("0", Eval2.eval(code,  1)); // No primes 1 or below
         assertEquals("1", Eval2.eval(code,  2)); // 2
@@ -347,7 +347,7 @@ i=v.f;
 if (arg) v.f=1;
 return i;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 2;", code.print());
         assertEquals("2", Eval2.eval(code, 0));
         assertEquals("2", Eval2.eval(code, 1));
@@ -370,7 +370,7 @@ if (arg) {
 }
 return i;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Region,.f,0);", code.print());
     }
 
@@ -389,7 +389,7 @@ if (v1) {
 }
 return v0;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return S;", code.print());
     }
 
@@ -407,7 +407,7 @@ if (arg+1) arg= 0;
 while (arg) v.f = 2;
 return i;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return arg;", code.print());
     }
 
@@ -424,7 +424,7 @@ while(1) {
 }
 return v;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return S;", code.print());
     }
 
@@ -439,7 +439,7 @@ while( -arg )
 while(1)
   arg = arg+ptr.v;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Top;", code.print());
     }
 
@@ -457,7 +457,7 @@ while (arg) {
 }
 return i;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 0;", code.print());
     }
 
@@ -477,7 +477,7 @@ while(arg) {
 }
 return arg;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 0;", code.print());
     }
 
@@ -495,7 +495,7 @@ if (arg) {
 }
 return v;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return S;", code.print());
     }
 
@@ -514,7 +514,7 @@ while (arg > 0) {
 }
 return v;
                 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         //assertEquals("return new S;", code.print());
     }
 
@@ -531,7 +531,7 @@ while(0>=0) {
 }
 return 0;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Top;", code.print());
     }
 
@@ -549,7 +549,7 @@ u32 v0=0;
     return v1;
 }
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 0;", code.print());
     }
 
diff --git a/src/test/java/com/seaofnodes/simple/Chapter14FloatTest.java b/src/test/java/com/seaofnodes/simple/Chapter14FloatTest.java
index cf7d3481..51397e77 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter14FloatTest.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter14FloatTest.java
@@ -20,7 +20,7 @@ public class Chapter14FloatTest {
             {"f32 rounded=arg+16777216.0; return rounded;", "1.6777232E7", "1.6777199E7"}
         };
         for( String[] test : tests ) {
-            var code = new CodeGen(test[0]).parse().iter().typeCheck();
+            var code = new CodeGen(test[0]).driver(CodeGen.Phase.TypeCheck);
             assertEquals(test[0],test[1],Eval2.eval(code,17));
             assertEquals(test[0],test[2],Eval2.eval(code,-17));
         }
@@ -28,7 +28,7 @@ public class Chapter14FloatTest {
 
 
     @Test public void testSubZeroFloat() {
-        var code = new CodeGen("flt x = arg; return 0-x;").parse().iter().typeCheck();
+        var code = new CodeGen("flt x = arg; return 0-x;").driver(CodeGen.Phase.TypeCheck);
         // Compare strings so +0.0 and -0.0 remain distinct.
         assertEquals("0.0", Eval2.eval(code,0));
         assertEquals("-1.0", Eval2.eval(code,1));
@@ -42,7 +42,7 @@ public class Chapter14FloatTest {
             {"return 2.5; return 7;", "2.5"}
         } ) {
             String src = test[0];
-            var code = new CodeGen(src).parse().iter().typeCheck();
+            var code = new CodeGen(src).driver(CodeGen.Phase.TypeCheck);
             assertEquals(src,test[1],Eval2.eval(code,0));
         }
     }
@@ -55,7 +55,7 @@ public class Chapter14FloatTest {
 """
 return 3.14;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 3.14;", code.print());
         assertEquals("3.14", Eval2.eval(code,  0));
     }
@@ -66,7 +66,7 @@ return 3.14;
 """
 return 3.14;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 3.14;", code.print());
         assertEquals("3.14", Eval2.eval(code,  0));
     }
@@ -83,7 +83,7 @@ while( 1 ) {
 }
 return guess;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Loop,(flt)arg,(((ToFloat/Phi_guess)+Phi_guess)*0.5f));", code.print());
         assertEquals("3.0", Eval2.eval(code,  9));
         assertEquals("1.414213562373095", Eval2.eval(code,  2));
@@ -96,7 +96,7 @@ return guess;
 flt x = arg;
 return x+1==x;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return ((flt)arg==(ToFloat+1.0f));", code.print());
         assertEquals("0", Eval2.eval(code, 1));
     }
diff --git a/src/test/java/com/seaofnodes/simple/Chapter14Test.java b/src/test/java/com/seaofnodes/simple/Chapter14Test.java
index ebc94d21..95a5ee81 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter14Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter14Test.java
@@ -16,7 +16,7 @@ public class Chapter14Test {
 """
 return 3.14;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 3.14;", code.print());
         assertEquals("3.14", Eval2.eval(code,  0));
     }
@@ -32,7 +32,7 @@ if( b < 0 ) c = -1;
 if( b > 2 ) c =  1;
 return c;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 99;", code.print());
         assertEquals("99", Eval2.eval(code,  0));
     }
@@ -45,7 +45,7 @@ u8 b = 123;
 b = b + 456;// Truncate
 return b;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 67;", code.print());
         assertEquals("67", Eval2.eval(code,  0));
     }
@@ -59,7 +59,7 @@ u8 b = 123;
 while( b ) b = b + 456;// Truncate
 return b;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 0;", code.print());
     }
 
@@ -72,7 +72,7 @@ b = b + 456;// Truncate
 u1 c = b;   // No more truncate needed
 return c;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 1;", code.print());
         assertEquals("1", Eval2.eval(code,  0));
     }
@@ -85,7 +85,7 @@ int b = 123;
 b = b+456 & 31;                 // Precedence
 return b;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 3;", code.print());
         assertEquals("3", Eval2.eval(code,  0));
     }
@@ -99,7 +99,7 @@ struct Foo { u1 b; };
 f.b = 123;
 return f.b;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 1;", code.print());
         assertEquals("1", Eval2.eval(code,  0));
     }
@@ -111,7 +111,7 @@ return f.b;
 i8 b = 255;                     // Chopped
 return b;                       // Sign extend
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return -1;", code.print());
         assertEquals("-1", Eval2.eval(code,  0));
     }
@@ -124,7 +124,7 @@ i8 b = arg;
 b = b + 1;// Truncate
 return b;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return (((((arg<<56)>>56)+1)<<56)>>56);", code.print());
         assertEquals("1", Eval2.eval(code, 0));
         assertEquals("-128", Eval2.eval(code, 127));
@@ -138,7 +138,7 @@ u16 mask = (1<<16)-1;           // AND mask
 int c = 123456789 & mask;
 return c;                       //
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 52501;", code.print());
         assertEquals("52501", Eval2.eval(code,  0));
     }
@@ -149,7 +149,7 @@ return c;                       //
 """
 return (arg | 123 ^ 456) >>> 1;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return (((arg|123)^456)>>>1);", code.print());
         assertEquals("217", Eval2.eval(code,  0));
     }
@@ -162,7 +162,7 @@ flt f = arg;
 arg = f & 1;
 return arg;
 """);
-        try { code.parse().iter().typeCheck(); fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
         catch( Exception e ) { assertEquals("Cannot '&' flt",e.getMessage()); }
     }
 
@@ -175,8 +175,8 @@ while(arg) v1=-v0;
 while(v1) break;
 return v1;
 """);
-        code.parse().iter();
-        assertEquals("return (Phi(Loop,((1<<arg)&1),0)&Phi(Loop,Shl,4294967295));", code.print());
+        code.parse().iter().finalizeIR();
+        assertEquals("return Phi(Loop,(((1<<arg)&1)&Shl),0);", code.print());
         assertEquals("1", Eval2.eval(code,  0));
     }
 
@@ -194,7 +194,7 @@ if(0&0>>>0) {
 }
 return v0;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 0;", code.print());
         assertEquals("0", Eval2.eval(code,  0));
     }
@@ -220,7 +220,7 @@ f32 ff32 = 3.141592653589793;  if( ff32 != 3.1415927410125732) return 5;
 
 return 0;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         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 4265aecc..c67d1eac 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter15Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter15Test.java
@@ -75,7 +75,7 @@ public class Chapter15Test {
 """
 return 3.14;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 3.14;", code.print());
         assertEquals("3.14", Eval2.eval(code,  0));
     }
@@ -89,7 +89,7 @@ struct C { !C? !l; };
 c.l = c;
 return c;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return C;", code.print());
         assertEquals("C{l=$cyclic}", Eval2.eval(code,  0));
     }
@@ -108,7 +108,7 @@ while (i < old#) {
 output[i] = 1;
 return output;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return [u8];", code.print());
         assertEquals("\u0001", Eval2.eval(code,  0));
     }
@@ -120,7 +120,7 @@ return output;
 int[] is = new int[2];
 return is[1];
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 0;", code.print());
         assertEquals("0", Eval2.eval(code,  0));
     }
@@ -133,7 +133,7 @@ int[] is = new int[2];
 int[] is2 = new int[2];
 return is[1];
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 0;", code.print());
         assertEquals("0", Eval2.eval(code,  0));
     }
@@ -147,7 +147,7 @@ a[0] = 1;
 a[1] = 2;
 return a[0];
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 1;", code.print());
         assertEquals("1", Eval2.eval(code,  0));
     }
@@ -160,7 +160,7 @@ struct A { int i; };
 !A?[] !a = new !A?[2];
 return a;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return [*A?];", code.print());
         assertEquals("*A {int !i; }?[ null,null]", Eval2.eval(code, 0));
     }
@@ -189,7 +189,7 @@ else {
 }
 return rez;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Region,1.2,.y,2.3);", code.print());
         assertEquals("3.14", Eval2.eval(code, 0));
         assertEquals("1.2", Eval2.eval(code, 1));
@@ -214,7 +214,7 @@ if( iss[arg] )
     if( iss[arg][2] )
         rez = iss[arg][2].y;
 return rez;""");
-        code.parse().iter().typeCheck();
+        code.driver(CodeGen.Phase.TypeCheck);
         assertEquals("return Phi(Region,1.2,1.2,.y);", code.print());
         assertEquals("3.14", Eval2.eval(code,  0));
         try { Eval2.eval(code, 10); fail(); } // Fails AIOOBE in Eval2, no range checks
@@ -232,7 +232,7 @@ root._kids = new !Tree?[2]; // NO BANG SO ARRAY IS OF IMMUTABLE TREES????
 root._kids[0] = new Tree;
 return root;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Tree;", code.print());
         assertEquals("Tree{_kids=*Tree?[ Tree{_kids=null},null]}", Eval2.eval(code,  0));
     }
@@ -244,7 +244,7 @@ return root;
 struct S { int a; int[] !b; };
 return 0;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 0;", code.print());
     }
 
@@ -267,7 +267,7 @@ while( i < ary# - 1 ) {
 }
 return ary[1] * 1000 + ary[3]; // 1 * 1000 + 6
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return (.[]+(.[]*1000));", code.print());
         assertEquals("1006", Eval2.eval(code,  4));
     }
@@ -276,7 +276,7 @@ return ary[1] * 1000 + ary[3]; // 1 * 1000 + 6
     public void sieveOEratosthenes() throws IOException {
         String src = Files.readString(Path.of("src/test/java/com/seaofnodes/simple/progs/sieve.smp"));
         CodeGen code = new CodeGen(src+"return sieve(arg);");
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return [u32];", code.print());
         assertEquals("u32[ 2,3,5,7,11,13,17,19]",Eval2.eval(code, 20));
     }
@@ -293,7 +293,7 @@ s2.f = 2.0;
 if (arg) s1 = new S;
 return s1.i + s1.f;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return ((flt).i+.f);", code.print());
         assertEquals("0.0", Eval2.eval(code,  0));
     }
@@ -305,7 +305,7 @@ return s1.i + s1.f;
 """
 return new flt;
 """);
-        try { code.parse().iter(); fail(); }
+        try { code.parse().iter().finalizeIR(); fail(); }
         catch( Exception e ) { assertEquals("Cannot allocate a flt",e.getMessage()); }
     }
 
@@ -313,10 +313,10 @@ return new flt;
     public void testBad1() {
         CodeGen code = new CodeGen(
 """
-int is = new int[2];
+flt is = new int[2];
 """);
-        try { code.parse().iter(); fail(); }
-        catch( Exception e ) { assertEquals("Type *[int] is not of declared type int",e.getMessage()); }
+        try { code.parse().iter().finalizeIR(); fail(); }
+        catch( Exception e ) { assertEquals("Type *[int] is not of declared type flt",e.getMessage()); }
     }
 
     @Test
@@ -326,7 +326,7 @@ int is = new int[2];
 int[] is = new int[3.14];
 return is[1];
 """);
-        try { code.parse().iter(); fail(); }
+        try { code.parse().iter().finalizeIR(); fail(); }
         catch( Exception e ) { assertEquals("Cannot allocate an array with length 3.14",e.getMessage()); }
     }
 
@@ -336,7 +336,7 @@ return is[1];
 int[] is = new int[arg];
 return is[1];
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 0;", code.print());
         assertEquals("0", Eval2.eval(code,  4));
         try { Eval2.eval(code,-1); fail(); }
@@ -369,7 +369,7 @@ while(v5+(0&0)) {
 }
 return v1;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 0;", code.print());
         assertEquals("0", Eval2.eval(code,  0));
     }
@@ -383,8 +383,9 @@ while(0) {}
 u32 v7=0;
 int v8=0;
 while(0<--1>>>---(v7*0==v8)) {}
+return 0;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 0;", code.print());
     }
 
@@ -407,8 +408,9 @@ else {
             }
         }
 }
+return 0;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         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 78e468cd..27766f20 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter16Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter16Test.java
@@ -17,7 +17,7 @@ public class Chapter16Test {
 """
 return 3.14;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 3.14;", code.print());
         assertEquals("3.14", Eval2.eval(code,  0));
     }
@@ -30,7 +30,7 @@ return 3.14;
 int x, y;
 return x+y;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 0;", code.print());
         assertEquals("0", Eval2.eval(code,  0));
     }
@@ -41,7 +41,7 @@ return x+y;
 int x=2, y=x+1;
 return x+y;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 5;", code.print());
         assertEquals("5", Eval2.eval(code,  0));
     }
@@ -54,7 +54,7 @@ struct X { int x=3; };
 X z = new X;
 return z.x;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 3;", code.print());
         assertEquals("3", Eval2.eval(code,  0));
     }
@@ -66,7 +66,7 @@ struct X { int x=3; };
 X z = new X { x = 4; };
 return z.x;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 4;", code.print());
         assertEquals("4", Eval2.eval(code,  0));
     }
@@ -87,7 +87,7 @@ LLI? next = head.next;
 if( !next ) return 1;
 return next.i;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Region,0,1,.i);", code.print());
         assertEquals("0", Eval2.eval(code,  0));
         assertEquals("1", Eval2.eval(code,  1));
@@ -118,7 +118,7 @@ LLI? next = head.next;
 if( !next ) return 1;
 return next.i;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Region,0,1,.i);", code.print());
         assertEquals("0", Eval2.eval(code,  0));
         assertEquals("1", Eval2.eval(code,  1));
@@ -143,7 +143,7 @@ struct Square {
 };
 return new Square;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         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));
@@ -167,7 +167,7 @@ return new Square;
         """;
 
     @Test public void testConstructorMemory() {
-        var code = new CodeGen(CONSTRUCTOR_MEMORY).parse().iter();
+        var code = new CodeGen(CONSTRUCTOR_MEMORY).parse().iter().finalizeIR();
         assertEquals("111249",Eval2.eval(code,0));
         assertEquals("222352",Eval2.eval(code,1));
     }
diff --git a/src/test/java/com/seaofnodes/simple/Chapter17aTest.java b/src/test/java/com/seaofnodes/simple/Chapter17aTest.java
index 4a69c33d..b8a25016 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter17aTest.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter17aTest.java
@@ -17,7 +17,7 @@ int x=2, y=3;
 if( arg ) { int x = y; x = x*x; y=x; } // Shadow final x
 return y;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Region,9,3);", code.print());
         assertEquals("3", Eval2.eval(code, 0));
         assertEquals("9", Eval2.eval(code, 1));
@@ -30,7 +30,7 @@ struct X { int ~x; };
 X z = new X { x=3; };
 return z.x;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 3;", code.print());
         assertEquals("3", Eval2.eval(code,  0));
     }
@@ -42,7 +42,7 @@ struct Point { int ~x, ~y; };
 Point p = new Point { x=3; y=4; };
 return p;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return (const)Point;", code.print());
         assertEquals("Point{x=3,y=4}", Eval2.eval(code,  0));
     }
@@ -55,7 +55,7 @@ Point p = new Point { x=5; y=6; };
 p.x++;
 return p;
 """);
-        try { code.parse().iter().typeCheck(); fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
         catch( Exception e ) { assertEquals("Cannot modify final field 'x'",e.getMessage()); }
     }
 
@@ -67,7 +67,7 @@ Point p = new Point;
 p.x++;
 return p;
 """);
-        try { code.parse().iter().typeCheck(); fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
         catch( Exception e ) { assertEquals("Cannot modify final field 'x'",e.getMessage()); }
     }
 
@@ -75,7 +75,7 @@ return p;
     public void testStructFinal3() {
         for( String fields : new String[] { "var x; var y;", "int[] !x;", "int[] !x;" } ) {
             String src = "struct Point { "+fields+" }; Point p = new Point; p.x++; return p;";
-            try { new CodeGen(src).parse().iter(); fail(fields); }
+            try { new CodeGen(src).parse().iter().finalizeIR(); fail(fields); }
             catch( Exception e ) { assertEquals("'Point' is not fully initialized, field 'x' needs to be set in a constructor",e.getMessage()); }
         }
     }
@@ -88,7 +88,7 @@ Point p = new Point;
 p.x++;
 return p;
 """);
-        try { code.parse().iter(); fail(); }
+        try { code.parse().iter().finalizeIR(); fail(); }
         catch( Exception e ) { assertEquals("Cannot reassign final 'x'",e.getMessage()); }
     }
 
@@ -100,7 +100,7 @@ struct Point { var x=3; var y=4; };
 p.x++;
 return p;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Point;", code.print());
         assertEquals("Point{x=4,y=4}", Eval2.eval(code,  0));
     }
diff --git a/src/test/java/com/seaofnodes/simple/Chapter17bTest.java b/src/test/java/com/seaofnodes/simple/Chapter17bTest.java
index a761a31b..9185aec8 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter17bTest.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter17bTest.java
@@ -40,7 +40,7 @@ public class Chapter17bTest {
 """
 return 1;
 """);
-        code.parse().iter().typeCheck();
+        code.driver(CodeGen.Phase.TypeCheck);
         assertEquals("return 1;", code.print());
         assertEquals("1", Eval2.eval(code,  0));
     }
@@ -52,7 +52,7 @@ return 1;
         CodeGen code = new CodeGen("""
 return arg++;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return arg;", code.print());
         assertEquals("0", Eval2.eval(code, 0));
     }
@@ -62,7 +62,7 @@ return arg++;
         CodeGen code = new CodeGen("""
 return arg+++arg++;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return ((arg<<1)+1);", code.print());
         assertEquals("1", Eval2.eval(code, 0));
     }
@@ -73,7 +73,7 @@ return arg+++arg++;
 //   -(arg--)-(arg--)
 return -arg---arg--;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return (-((arg<<1)+-1));", code.print());
         assertEquals("1", Eval2.eval(code, 0));
     }
@@ -86,7 +86,7 @@ xs[0]++;
 xs[1]++;
 return xs[0];
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 1;", code.print());
         assertEquals("1", Eval2.eval(code, 2));
     }
@@ -98,7 +98,7 @@ u8[] !xs = new u8[1];
 xs[0]--;
 return xs[0];
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 255;", code.print());
         assertEquals("255", Eval2.eval(code, 2));
     }
@@ -111,7 +111,7 @@ struct S { u16 x; };
 s.x--;
 return s.x;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 65535;", code.print());
         assertEquals("65535", Eval2.eval(code, 2));
     }
@@ -119,7 +119,7 @@ return s.x;
     @Test
     public void testInc6() {
         CodeGen code = new CodeGen("return --arg;");
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return (arg+-1);", code.print());
         assertEquals("-1", Eval2.eval(code, 0));
     }
@@ -127,7 +127,7 @@ return s.x;
     @Test
     public void testInc7() {
         CodeGen code = new CodeGen("u8 x=0; return --x;");
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 255;", code.print());
         assertEquals("255", Eval2.eval(code, 0));
     }
@@ -135,7 +135,7 @@ return s.x;
     @Test
     public void testInc8() {
         CodeGen code = new CodeGen("int x; x+=2; return x+=3;");
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 5;", code.print());
         assertEquals("5", Eval2.eval(code, 0));
     }
@@ -143,14 +143,14 @@ return s.x;
     @Test
     public void testInc9() {
         CodeGen code = new CodeGen("flt x = 1.5; x++; return x;");
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         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;");
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("2",Eval2.eval(code,0));
     }
 
@@ -158,73 +158,73 @@ return s.x;
     // ---------------------------------------------------------------
     @Test public void testVar0() {
         CodeGen code = new CodeGen("var d; return d;");
-        try { code.parse().iter(); fail(); }
+        try { code.parse().iter().finalizeIR(); fail(); }
         catch( Exception e ) { assertEquals("Syntax error, expected =expression: ;",e.getMessage()); }
     }
 
     @Test public void testVar1() {
         CodeGen code = new CodeGen("val d; return d;");
-        try { code.parse().iter(); fail(); }
+        try { code.parse().iter().finalizeIR(); fail(); }
         catch( Exception e ) { assertEquals("Syntax error, expected =expression: ;",e.getMessage()); }
     }
 
     @Test public void testVar2() {
         CodeGen code = new CodeGen("int x; x=3; x++; return x; // Ok, no initializer so x is mutable ");
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 4;", code.print());
         assertEquals("4", Eval2.eval(code, 0));
     }
 
     @Test public void testVar3() {
         CodeGen code = new CodeGen("int x=3; x++; return x; // Ok, primitive so x is mutable despite initializer ");
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 4;", code.print());
         assertEquals("4", Eval2.eval(code, 0));
     }
 
     @Test public void testVar4() {
         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().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 1;", code.print());
         assertEquals("1", Eval2.eval(code, 0));
     }
 
     @Test public void testVar5() {
         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().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 4;", code.print());
         assertEquals("4", Eval2.eval(code, 0));
     }
 
     @Test public void testVar6() {
         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().iter().typeCheck(); fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
         catch( Exception e ) { assertEquals("Cannot modify final field 'x'",e.getMessage()); }
     }
 
     @Test public void testVar7() {
         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().iter().typeCheck(); fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
         catch( Exception e ) { assertEquals("Cannot modify final field 'x'",e.getMessage()); }
     }
 
     @Test public void testVar8() {
         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().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 1;", code.print());
         assertEquals("1", Eval2.eval(code, 0));
     }
 
     @Test public void testVar9() {
         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().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 1;", code.print());
         assertEquals("1", Eval2.eval(code, 0));
     }
 
     @Test public void testVar10() {
         CodeGen code = new CodeGen("struct S{int x;}; ~S s=new S; s.x++; return s.x; // Error, has val so x is immutable ");
-        try { code.parse().iter().typeCheck(); fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
         catch( Exception e ) { assertEquals("Cannot modify final field 'x'",e.getMessage()); }
     }
 
@@ -242,7 +242,7 @@ foo.bar.x++;   // Ok foo and foo.bar and foo.bar.x are all mutable
 ~Foo xfoo = foo; // Throw away mutability
 xfoo.bar.x++;   // Error, cannot mutate through xfoo
  """);
-        try { code.parse().iter().typeCheck(); fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
         catch( Exception e ) { assertEquals("Cannot modify final field 'x'",e.getMessage()); }
     }
 
@@ -263,7 +263,7 @@ foo.bar.x++;           // Bumps to 5
 int x5 = xfoo.bar.x;   // Ok to read through xfoo, gets 5
 return x4*10+x5;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 45;", code.print());
         assertEquals("45", Eval2.eval(code, 0));
     }
@@ -273,7 +273,7 @@ return x4*10+x5;
         CodeGen code = new CodeGen("""
 int i,i++;
 """);
-        try { code.parse().iter().typeCheck(); fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
         catch( Exception e ) { assertEquals("Redefining name 'i'",e.getMessage()); }
     }
 
@@ -288,7 +288,7 @@ A x = new A {
     b = new B;
 };
 """);
-        try { code.parse().iter(); fail(); }
+        try { code.parse().iter().finalizeIR(); fail(); }
         catch( Exception e ) { assertEquals("Cannot read uninitialized field 'b'",e.getMessage()); }
     }
 
@@ -301,7 +301,7 @@ return new A {
     if (arg) b = new B; // Constructor ends with partial init of b
 }.b;
 """);
-        try { code.parse().iter(); fail(); }
+        try { code.parse().iter().finalizeIR(); fail(); }
         catch( Exception e ) { assertEquals("'A' is not fully initialized, field 'b' needs to be set in a constructor",e.getMessage()); }
     }
 
@@ -315,7 +315,7 @@ val s = new S{x = 2;};
 return x;
 """
 );
-        try { code.parse().iter().typeCheck(); fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
         catch( Exception e ) { assertEquals("Cannot reassign final 'x'",e.getMessage()); }
     }
 
@@ -334,7 +334,7 @@ focus(me);
 return me;
 """
 );
-        try { code.parse().iter().typeCheck(); fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
         catch( Exception e ) { assertEquals("Syntax error, expected =expression: ;",e.getMessage()); }
     }
 
@@ -344,7 +344,7 @@ return me;
         CodeGen code = new CodeGen("""
 return arg ? 1 : 2;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Region,1,2);", code.print());
         assertEquals("2", Eval2.eval(code, 0));
         assertEquals("1", Eval2.eval(code, 1));
@@ -355,7 +355,7 @@ return arg ? 1 : 2;
         CodeGen code = new CodeGen("""
 return arg ? 0 : arg;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 0;", code.print());
         assertEquals("0", Eval2.eval(code, 0));
     }
@@ -367,7 +367,7 @@ struct Bar { int x; };
 var b = arg ? new Bar : null;
 return b ? b.x++ + b.x++ : -1;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Region,((.x<<1)+1),-1);", code.print());
         assertEquals("-1", Eval2.eval(code, 0));
         assertEquals("1", Eval2.eval(code, 1));
@@ -380,7 +380,7 @@ struct Bar { int x; };
 var b = arg ? new Bar;
 return b ? b.x++ + b.x++ : -1;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Region,((.x<<1)+1),-1);", code.print());
         assertEquals("-1", Eval2.eval(code, 0));
         assertEquals("1", Eval2.eval(code, 1));
@@ -394,7 +394,7 @@ 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"
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Region,.x,0,.x);", code.print());
         assertEquals("0", Eval2.eval(code, 0));
         assertEquals("1", Eval2.eval(code, 1));
@@ -407,7 +407,7 @@ return b ? b.next ? b.next.x : b.x; // parses "b ? (b.next ? b.next.x : b.x) : 0
 flt f=arg?1:1.2;
 return f;   // missing widening
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Region,1.0f,1.2);", code.print());
         assertEquals("1.2", Eval2.eval(code,  0));
     }
@@ -419,7 +419,7 @@ return f;   // missing widening
 struct S{};
 return arg ? 7 : new S;
 """);
-        try { code.parse().iter().typeCheck(); fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
         catch( Exception e ) { assertEquals("No common type amongst int and reference",e.getMessage()); }
     }
 
@@ -432,7 +432,7 @@ for( int i=0; i<arg; i++ )
     sum += i;
 return sum;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         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));
@@ -445,7 +445,7 @@ for( ; i<arg; i++ )
     sum += i;
 return sum;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         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));
@@ -460,7 +460,7 @@ for( int i=0; ; i++ ) {
 }
 return sum;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         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));
@@ -473,7 +473,7 @@ for( int i=0; i<arg; )
     sum += i++;
 return sum;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         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));
@@ -486,7 +486,7 @@ for( int i=0; i<arg; i++ )
     sum += i;
 return i;
 """);
-        try { code.parse().iter(); fail(); }
+        try { code.parse().iter().finalizeIR(); fail(); }
         catch( Exception e ) { assertEquals("Undefined name 'i'",e.getMessage()); }
     }
     @Test
@@ -494,7 +494,7 @@ return i;
         CodeGen code = new CodeGen("""
 for(;;arg++;) {}
 """);
-        try { code.parse().iter(); fail(); }
+        try { code.parse().iter().finalizeIR(); fail(); }
         catch( Exception e ) { assertEquals("Syntax error, expected Unexpected code after expression: ;",e.getMessage()); }
     }
 
@@ -510,7 +510,7 @@ struct A{
 };
 return new A;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return A;", code.print());
         assertEquals("A{f1=null,f2=null}", Eval2.eval(code,0));
     }
@@ -524,7 +524,7 @@ struct A{
 };
 return new A.not_array_of_b;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return [*B?];", code.print());
         assertEquals("*B?[]", Eval2.eval(code,0));
     }
@@ -543,7 +543,7 @@ for( ; ptr; ptr = ptr.next )
     sum += ptr.i;
 return sum;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return Phi(Loop,0,(Phi_sum+.i));", code.print());
         assertEquals("45", Eval2.eval(code, 10));
     }
diff --git a/src/test/java/com/seaofnodes/simple/Chapter18Test.java b/src/test/java/com/seaofnodes/simple/Chapter18Test.java
index 6282f26c..e310366d 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter18Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter18Test.java
@@ -91,7 +91,7 @@ public class Chapter18Test {
              "No common type amongst int and reference"}
         } ) {
             try {
-                new CodeGen(test[0]).parse().iter().typeCheck();
+                new CodeGen(test[0]).driver(CodeGen.Phase.TypeCheck);
                 fail("Expected incompatible return types: " + test[0]);
             } catch( Parser.ParseException e ) {
                 assertEquals(test[1],e.getMessage());
@@ -140,7 +140,7 @@ while(arg--) {
 }
 return a;
 """);
-        code.driver(CodeGen.Phase.Schedule);
+        code.driver(CodeGen.Phase.TypeCheck);
         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));
@@ -157,7 +157,7 @@ return a;
 {int -> int}? x2 = null; // null function ptr
 return x2;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return null;", code._stop.toString());
         assertEquals("null", Eval2.eval(code, 0 ) );
     }
@@ -170,7 +170,7 @@ return x2;
     x*x;
 };
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return (Parm_x(sq,int)*x);", code._stop.toString());
         //assertEquals("{ int -> int #1}", Eval2.eval(code, 3));
     }
@@ -185,7 +185,7 @@ var sq = { int x ->
 return sq(arg)+sq(3);
 """);
         code.driver(Phase.LocalSched);
-        assertEquals("Stop[ return (#2+#2); return (Parm_x(sq,int)*x); ]", code._stop.toString());
+        assertEquals("Stop[ return (Parm_x(sq,int)*x); return (#2+#2); ]", code._stop.toString());
         assertEquals("13", Eval2.eval(code, 2));
     }
 
@@ -197,7 +197,7 @@ return sq(arg)+sq(3);
 int cnt=1;
 return { -> cnt; };
 """);
-        try { code.parse().iter(); fail(); }
+        try { code.parse().iter().finalizeIR(); fail(); }
         catch( Exception e ) { assertEquals("Variable 'cnt' is out of function scope and must be a final constant",e.getMessage()); }
     }
 
@@ -209,7 +209,7 @@ return { -> cnt; };
 val cnt=2;
 return { -> cnt; }();
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         assertEquals("return 2;", code._stop.toString());
         assertEquals("2", Eval2.eval(code, 0));
     }
@@ -222,8 +222,8 @@ return { -> cnt; }();
 var fcn = arg ? { int x -> x*x; } : { int x -> x+x; };
 return fcn(3);
 """);
-        code.parse().iter();
-        assertEquals("Stop[ return #2; return (Parm_x($fun1,int,3)*x); return (Parm_x($fun2,int,3)<<1); ]", code._stop.toString());
+        code.parse().iter().finalizeIR();
+        assertEquals("Stop[ return (Parm_x($fun2,int,3)<<1); return (Parm_x($fun1,int,3)*x); return #2; ]", code._stop.toString());
         assertEquals("6", Eval2.eval(code, 0));
         assertEquals("9", Eval2.eval(code, 1));
     }
@@ -232,8 +232,8 @@ return fcn(3);
     @Test
     public void testFcn5() {
         CodeGen code = new CodeGen("val fact = { int x -> x <= 1 ? 1 : x*fact(x-1); }; return fact(arg);");
-        code.parse().iter().typeCheck();
-        assertEquals("Stop[ return #2; return Phi(Region,1,(Parm_x(fact,int,arg,(x-1))*#2)); ]", code._stop.toString());
+        code.driver(CodeGen.Phase.TypeCheck);
+        assertEquals("Stop[ return Phi(Region,1,(Parm_x(fact,int,arg,(x-1))*#2)); return #2; ]", code._stop.toString());
         assertEquals( "1", Eval2.eval(code, 0));
         assertEquals( "1", Eval2.eval(code, 1));
         assertEquals( "2", Eval2.eval(code, 2));
@@ -265,7 +265,7 @@ val g = {->2;};
 return 2;
 """);
         code.driver(CodeGen.Phase.Schedule);
-        assertEquals("Stop[ return 1; return 1; return 2; ]", code._stop.toString());
+        assertEquals("Stop[ return 2; return 1; return 1; ]", code._stop.toString());
         assertEquals("1", Eval2.eval(code,  0));
     }
 
@@ -283,7 +283,7 @@ for(;;) {
 }
 """);
         code.driver(Phase.LocalSched);
-        assertEquals("Stop[ return #2; return Parm_i(x,int); ]", code._stop.toString());
+        assertEquals("Stop[ return Parm_i(x,int); return #2; ]", code._stop.toString());
         assertEquals("3", Eval2.eval(code,  0));
     }
 
@@ -321,7 +321,7 @@ val fcn = { !Person?[] !ps, int x ->
 var ps = new !Person?[2];
 ps[0] = new Person;
 ps[1] = new Person;
-fcn(ps,1);
+return fcn(ps,1);
 """);
         code.driver(Phase.LocalSched);
         assertEquals("return 0;", code._stop.toString());
@@ -342,7 +342,7 @@ for(;;) {
 }
 return 1;
 """);
-        try { code.parse().iter(); fail(); }
+        try { code.parse().iter().finalizeIR(); fail(); }
         catch( Exception e ) { assertEquals("No active loop for a break or continue",e.getMessage()); }
     }
 
@@ -356,8 +356,9 @@ for(;;) {
     if (i2i(2) == arg) break;
     i2i = null;
 }
+return 0;
 """);
-        try { code.parse().iter().typeCheck(); fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
         catch( Exception e ) { assertEquals("Might be null calling { int -> int #1}?",e.getMessage()); }
     }
 
@@ -369,7 +370,7 @@ for(;;) {
 val f = { int i, int j -> return i+j; };
 return f();
 """);
-        try { code.parse().iter().typeCheck(); fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
         catch( Exception e ) { assertEquals("Expecting 2 arguments, but found 0",e.getMessage()); }
     }
 
@@ -387,7 +388,7 @@ for(;;) {
     if (s) return s.x;
 }
 """);
-        try { code.parse().iter().typeCheck(); fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
         catch( Exception e ) { assertEquals("Accessing unknown field 'x' from '*S'",e.getMessage()); }
     }
 
@@ -400,7 +401,7 @@ val g = { ->
 };
 return 0;
 """);
-        try { code.parse().iter().typeCheck(); fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
         catch( Exception e ) { assertEquals("No defined return type",e.getMessage()); }
     }
 
@@ -414,7 +415,7 @@ 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().iter();
+        code.parse().iter().finalizeIR();
         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));
@@ -454,7 +455,7 @@ if (i2i) return i2i(arg);
 return f2f(o)(1);
 """);
         code.driver(Phase.LocalSched);
-        assertEquals("Stop[ return Phi(Region,#2,1); return Parm_i(o,int); ]", code._stop.toString());
+        assertEquals("Stop[ return Parm_i(i2i.o,int); return Phi(Region,#2,1); ]", code._stop.toString());
         assertEquals("1", Eval2.eval(code,  2));
     }
 
@@ -488,7 +489,7 @@ return p.coffee_count;
         """;
 
     @Test public void testCallMemory() {
-        var code = new CodeGen(CALL_MEMORY).parse().iter();
+        var code = new CodeGen(CALL_MEMORY).parse().iter().finalizeIR();
         int[] calls={0};
         code._stop.walk(n -> { if(n instanceof CallNode) calls[0]++; return null; });
         assertEquals(2,calls[0]); // Keep real calls so this checks scheduling across them.
@@ -517,7 +518,7 @@ return p.coffee_count;
         """;
 
     @Test public void testRecursiveMemory() {
-        var code = new CodeGen(RECURSIVE_MEMORY).parse().iter();
+        var code = new CodeGen(RECURSIVE_MEMORY).parse().iter().finalizeIR();
         for(int n=0; n<7; n++)
             assertEquals(Long.toString((10L*(n+1)+n*(n+1)/2)*100+10+n),Eval2.eval(code,n));
     }
@@ -535,7 +536,7 @@ return p.coffee_count;
         """;
 
     @Test public void testInlineAllocationMemory() {
-        var code = new CodeGen(INLINE_MEMORY).parse().iter();
+        var code = new CodeGen(INLINE_MEMORY).parse().iter().finalizeIR();
         assertNull(code._stop.walk(n -> n instanceof CallNode ? n : null));
         assertEquals("400944",Eval2.eval(code,0));
         assertEquals("420946",Eval2.eval(code,2));
diff --git a/src/test/java/com/seaofnodes/simple/Chapter19Test.java b/src/test/java/com/seaofnodes/simple/Chapter19Test.java
index 2027dbd6..ac141247 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter19Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter19Test.java
@@ -22,7 +22,7 @@ public class Chapter19Test {
         con.toString();
         org.junit.Assert.assertNull(call.name());
 
-        var fun = new FunNode(null,tfp);
+        var fun = new FunNode(null,tfp,"printerTarget");
         fun._name = "printerTarget";
         fun.addDef(code._start);
         code.link(fun);
@@ -39,7 +39,7 @@ public class Chapter19Test {
         CodeGen code = new CodeGen("""
 return 0;
 """);
-        code.parse().iter().typeCheck();
+        code.driver(CodeGen.Phase.TypeCheck);
         assertEquals("return 0;", code._stop.toString());
         assertEquals("0", Eval2.eval(code,  2));
     }
@@ -295,6 +295,7 @@ for( int i=0; i<A#; i++ )
     A[i] = i;
 for( int i=0; i<A#; i++ )
     B[i] += A[i];
+return 0;
 """);
         code.driver(Phase.LocalSched,"x86_64_v2", "SystemV");
         assertEquals("return 0;", code.print());
@@ -339,7 +340,7 @@ val fcn = arg ? { int x -> x*x; } : { int x -> x+x; };
 return fcn(2)*10 + fcn(3);
 """);
         code.driver(Phase.LocalSched,"x86_64_v2", "SystemV");
-        assertEquals("Stop[ return (add,#2,(muli,#2)); return (mul,Parm_x($fun1,int),x); return (shli,Parm_x($fun2,int)); ]", code.print());
+        assertEquals("Stop[ return (shli,Parm_x($fun2,int)); return (mul,Parm_x($fun1,int),x); return (add,#2,(muli,#2)); ]", code.print());
     }
 
     @Test
@@ -350,16 +351,16 @@ val sq = { int x -> x*x; };
 return sq(arg) + sq(3);
 """);
         code.driver(Phase.LocalSched,"x86_64_v2", "SystemV");
-        assertEquals("Stop[ return (add,#2,#2); return (mul,Parm_x(sq,int),x); ]", code.print());
+        assertEquals("Stop[ return (mul,Parm_x(sq,int),x); return (add,#2,#2); ]", code.print());
     }
 
     @Test public void testSelectedMemory() {
         for( String cpu : new String[]{"x86_64_v2","riscv","arm"} )
             for( String src : new String[]{Chapter10Test.NESTED_MEMORY,Chapter16Test.CONSTRUCTOR_MEMORY,
                                           Chapter18Test.CALL_MEMORY,Chapter18Test.RECURSIVE_MEMORY} ) {
-                var code = new CodeGen(src).parse().iter().typeCheck();
+                var code = new CodeGen(src).driver(CodeGen.Phase.TypeCheck);
                 var aliases = memoryPhis(code._stop);
-                code.loopTree().driver(CodeGen.Phase.InstSelect,cpu,"SystemV");
+                code.loopTree().driver(CodeGen.Phase.Select,cpu,"SystemV");
                 assertEquals(aliases,memoryPhis(code._stop));
                 code.driver(CodeGen.Phase.Schedule).localSched();
                 code._stop.walk(n -> {
diff --git a/src/test/java/com/seaofnodes/simple/Chapter20Test.java b/src/test/java/com/seaofnodes/simple/Chapter20Test.java
index 93d8caae..3b1ca4ff 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter20Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter20Test.java
@@ -1,5 +1,7 @@
 package com.seaofnodes.simple;
 
+import com.seaofnodes.simple.codegen.RegAllocTestSupport.CheckedCodeGen;
+
 
 import com.seaofnodes.simple.codegen.CodeGen;
 import com.seaofnodes.simple.print.ASMPrinter;
@@ -73,13 +75,14 @@ return f(s);
         // The entry of g can disappear before its Return is folded into f.
         // Exercise both worklist orders; deleting the entry does not kill 123.
         for( int seed=0; seed<64; seed++ ) {
-            CodeGen code = new CodeGen(src,com.seaofnodes.simple.type.TypeInteger.BOT,seed).parse().iter().typeCheck();
+            CodeGen code = new CodeGen(src,com.seaofnodes.simple.type.TypeInteger.BOT,seed).driver(CodeGen.Phase.TypeCheck);
             assertEquals("seed "+seed, "123", Eval2.eval(code,0));
         }
     }
 
 
     @org.junit.Rule public final org.junit.rules.ErrorCollector _errors = new org.junit.rules.ErrorCollector();
+
     @Test public void testAllocatorMasks() { com.seaofnodes.simple.codegen.RegAllocTestSupport.masks(); }
     @Test public void testAllocatorUnion() { com.seaofnodes.simple.codegen.RegAllocTestSupport.union(); }
     @Test public void testAllocatorCopyClobber() throws Exception { com.seaofnodes.simple.codegen.RegAllocTestSupport.copyClobber(); }
@@ -97,7 +100,7 @@ return f(s);
     @Test
     public void testJig() {
         CodeGen code = new CodeGen("return 0;");
-        code.parse().iter().typeCheck();
+        code.driver(CodeGen.Phase.TypeCheck);
         assertEquals("return 0;", code._stop.toString());
         assertEquals("0", Eval2.eval(code,  2));
     }
@@ -108,9 +111,8 @@ return f(s);
     }
 
     static void testCPU(String src, String cpu, String os, int spills, String stop) {
-        CodeGen code = new CodeGen(src);
+        CodeGen code = new CheckedCodeGen(src);
         code.driver(CodeGen.Phase.RegAlloc,cpu,os);
-        com.seaofnodes.simple.codegen.RegAllocTestSupport.checkRegisters(code);
         SpillStats.record(code,"Chapter20",cpu,os);
         SpillStats.checkSpills(spills,code._regAlloc._spillScaled);
         if( stop!=null ) assertEquals(stop,code._stop.toString());
@@ -150,7 +152,7 @@ val sqrt = { int x ->
 };
 return sqrt(arg) + sqrt(arg+2);
 """;
-        testTarget(src,"x86_64_v2", "SystemV",23,null);
+        testTarget(src,"x86_64_v2", "SystemV",40,null);
         testTarget(src,"riscv"    , "SystemV",17,null);
         testTarget(src,"arm"      , "SystemV",18,null);
     }
@@ -179,9 +181,9 @@ return sqrt(farg) + sqrt(farg+2.0);
     @Test
     public void testAlloc2() {
         String src = "int[] !xs = new int[3]; xs[arg]=1; return xs[arg&1];";
-        testTarget(src,"x86_64_v2","SystemV",4,"return .[];");
-        testTarget(src,"riscv","SystemV",8,"return .[];");
-        testTarget(src,"arm","SystemV",9,"return .[];");
+        testTarget(src,"x86_64_v2","SystemV",3,"return .[];");
+        testTarget(src,"riscv","SystemV",6,"return .[];");
+        testTarget(src,"arm","SystemV",6,"return .[];");
     }
 
     @Test
@@ -197,7 +199,7 @@ for( int i=0; i<ary#-1; i++ )
     ary[i+1] += ary[i];
 return ary[1] * 1000 + ary[3]; // 1 * 1000 + 6
 """;
-        testTarget(src,"x86_64_v2", "SystemV",7,"return .[];");
+        testTarget(src,"x86_64_v2", "SystemV",5,"return .[];");
         testTarget(src,"riscv"    , "SystemV",7,"return (add,.[],(mul,.[],1000));");
         testTarget(src,"arm"      , "SystemV",5,"return (add,.[],(mul,.[],1000));");
     }
@@ -240,9 +242,14 @@ s.cs[0] =  67; // C
 s.cs[1] = 108; // l
 hashCode(s);
 """;
-        testTarget(src,"x86_64_v2", "SystemV",15,null);
-        testTarget(src,"riscv"    , "SystemV", 10,null);
-        testTarget(src,"arm"      , "SystemV", 10,null);
+        // Without an explicit return, default main must be removed completely.
+        // Seed 0 previously left a loop with a missing branch successor.
+        for( String cpu : new String[]{"x86_64_v2","riscv","arm"} )
+            new CodeGen(src,com.seaofnodes.simple.type.TypeInteger.BOT,0)
+                .driver(CodeGen.Phase.Encoding,cpu,"SystemV");
+        testTarget(src,"x86_64_v2", "SystemV",0,null);
+        testTarget(src,"riscv"    , "SystemV",1,null);
+        testTarget(src,"arm"      , "SystemV",0,null);
     }
 
     @Test
@@ -343,8 +350,8 @@ for( int pc = 0; pc < program#; pc++ ) {
 return output;
 """;
         testTarget(src,"x86_64_v2", "SystemV",40,null);
-        testTarget(src,"riscv"    , "SystemV",42,null);
-        testTarget(src,"arm"      , "SystemV",34,null);
+        testTarget(src,"riscv"    , "SystemV",28,null);
+        testTarget(src,"arm"      , "SystemV",28,null);
         //assertEquals("Hello World!\n", Eval2.eval(code, 0, 10000));
     }
     // Original Chapter 20 allocation workload, kept fixed for cohort comparisons.
diff --git a/src/test/java/com/seaofnodes/simple/Chapter21AllocTest.java b/src/test/java/com/seaofnodes/simple/Chapter21AllocTest.java
index bc300217..b81483d8 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter21AllocTest.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter21AllocTest.java
@@ -21,7 +21,7 @@ val sqrt = { int x ->
 };
 return sqrt(arg) + sqrt(arg+2);
 """;
-        Chapter21Test.testCPU(src,"x86_64_v2", "Win64"  ,23,null);
+        Chapter21Test.testCPU(src,"x86_64_v2", "Win64"  ,40,null);
         Chapter21Test.testCPU(src,"riscv"    , "SystemV",19,null);
         Chapter21Test.testCPU(src,"arm"      , "SystemV",19,null);
     }
diff --git a/src/test/java/com/seaofnodes/simple/Chapter21Test.java b/src/test/java/com/seaofnodes/simple/Chapter21Test.java
index b19d1bb5..4bce96ab 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter21Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter21Test.java
@@ -4,6 +4,7 @@ import com.seaofnodes.isa.eval.EvalRisc5;
 
 import com.seaofnodes.isa.eval.EvalArm64;
 
+import com.seaofnodes.simple.codegen.RegAllocTestSupport.CheckedCodeGen;
 import com.seaofnodes.simple.codegen.CodeGen;
 import com.seaofnodes.simple.node.cpus.arm.arm;
 import com.seaofnodes.simple.node.cpus.riscv.riscv;
@@ -27,7 +28,7 @@ public class Chapter21Test {
                 else if(i==4) b.x=40;
             }
             return sum;
-            """).parse().iter();
+            """).parse().iter().finalizeIR();
         // The i==2 read still sees 10: three reads of 10, then three of 30.
         assertEquals("120",Eval2.eval(code,0));
         assertEquals("60",Eval2.eval(code,1));
@@ -103,39 +104,6 @@ public class Chapter21Test {
     }
 
 
-    @Test public void testNarrowStores() throws IOException {
-        for( String type : new String[]{"i8","u8","i16","u16"} ) {
-            String src = "struct S { "+type+" x; }; !S !s = new S; s.x = arg; return 0;";
-            CodeGen code = new CodeGen(src).driver("riscv","SystemV",null);
-            int stores=0;
-            for( var bb : code._cfg )
-                for( var node : bb.outs() )
-                    if( node instanceof com.seaofnodes.simple.node.cpus.riscv.StoreRISC st ) {
-                        stores++;
-                        assertEquals("Byte/short stores have no FP encoding",-1,st.regmap(4).nextReg((short)31));
-                    }
-            assertEquals(1,stores);
-            byte[] image = new byte[1<<20];
-            byte[] bits = code._encoding.bits();
-            System.arraycopy(bits,0,image,0,bits.length);
-            EvalRisc5 cpu = new EvalRisc5(image,1<<16);
-            cpu.regs[riscv.A0] = 0x8765;
-            assertEquals(0,cpu.step(100));
-            assertEquals(type.endsWith("8") ? 0x65 : 0x8765,
-                         type.endsWith("8") ? cpu.ld1z(1<<16) : cpu.ld2z(1<<16));
-            code = new CodeGen(src).driver(CodeGen.Phase.Encoding,"x86_64_v2",TestC.CALL_CONVENTION);
-            stores=0;
-            for( var bb : code._cfg )
-                for( var node : bb.outs() )
-                    if( node instanceof com.seaofnodes.simple.node.cpus.x86_64_v2.StoreX86 st ) {
-                        stores++;
-                        assertEquals("Byte/short stores have no XMM encoding",-1,st.regmap(4).nextReg((short)15));
-                    }
-            assertEquals(1,stores);
-        }
-    }
-
-
     @Test public void testArmCallInstructions() {
         EvalArm64 cpu = new EvalArm64(new byte[512],256);
         for( int delta : new int[]{4,32,-4} ) {
@@ -238,6 +206,52 @@ public class Chapter21Test {
     }
 
 
+    @Test public void testNarrowStores() throws IOException {
+        for( String type : new String[]{"i8","u8","i16","u16"} ) {
+            String src = "struct S { "+type+" x; }; !S !s = new S; s.x = arg; return 0;";
+            CodeGen code = new CodeGen(src).driver("riscv","SystemV",null);
+            int stores=0;
+            for( var bb : code._cfg )
+                for( var node : bb.outs() )
+                    if( node instanceof com.seaofnodes.simple.node.cpus.riscv.StoreRISC st ) {
+                        stores++;
+                        assertEquals("Byte/short stores have no FP encoding",-1,st.regmap(4).nextReg((short)31));
+                    }
+            assertEquals(1,stores);
+            byte[] image = new byte[1<<20];
+            byte[] bits = code._encoding.bits();
+            System.arraycopy(bits,0,image,0,bits.length);
+            EvalRisc5 cpu = new EvalRisc5(image,1<<16);
+            cpu.regs[riscv.A0] = 0x8765;
+            assertEquals(0,cpu.step(100));
+            assertEquals(type.endsWith("8") ? 0x65 : 0x8765,
+                         type.endsWith("8") ? cpu.ld1z(1<<16) : cpu.ld2z(1<<16));
+            code = new CodeGen(src).driver(CodeGen.Phase.Encoding,"x86_64_v2",TestC.CALL_CONVENTION);
+            stores=0;
+            for( var bb : code._cfg )
+                for( var node : bb.outs() )
+                    if( node instanceof com.seaofnodes.simple.node.cpus.x86_64_v2.StoreX86 st ) {
+                        stores++;
+                        assertEquals("Byte/short stores have no XMM encoding",-1,st.regmap(4).nextReg((short)15));
+                    }
+            assertEquals(1,stores);
+        }
+    }
+
+    @Test public void testNativeExitStatus() throws IOException {
+        Path source = Path.of("build/objs/nativeExit.c");
+        Files.createDirectories(source.getParent());
+        Files.writeString(source,"int main() { return 7; }\n");
+        try {
+            TestC.gcc(source.toString(),null,null,false,
+                      "build/objs/nativeExit"+(TestC.OS.startsWith("Windows") ? ".exe" : ""));
+        } catch( AssertionError error ) {
+            assertTrue(error.getMessage(),error.getMessage().contains("Program exit status"));
+            return;
+        }
+        fail("A failing native program must fail the test, even with empty stdout");
+    }
+
     @Test public void testCoalescing() { com.seaofnodes.simple.codegen.RegAllocTestSupport.coalescing(); }
     @Test public void testCopyForward() throws Exception { com.seaofnodes.simple.codegen.RegAllocTestSupport.copyForward(); }
     @Test public void testRisc64BitStore() {
@@ -278,8 +292,7 @@ public class Chapter21Test {
     }
 
     static void testCPU( String src, String cpu, String os, int spills, String stop ) {
-        CodeGen code = new CodeGen(src).driver(CodeGen.Phase.Encoding,cpu,os);
-        com.seaofnodes.simple.codegen.RegAllocTestSupport.checkRegisters(code);
+        CodeGen code = new CheckedCodeGen(src).driver(CodeGen.Phase.Encoding,cpu,os);
         SpillStats.record(code,"Chapter21",cpu,os);
         SpillStats.checkSpills(spills,code._regAlloc._spillScaled);
         if( stop != null )
@@ -422,7 +435,7 @@ public class Chapter21Test {
 
     @Test public void testPerson() throws IOException {
         String person = "6\n";
-        TestC.run("person", person, 0);
+        TestC.run("person21", person, 0);
 
         // Memory layout starting at PS:
         int ps = 1<<16;         // Person array pointer starts at heap start
@@ -433,7 +446,7 @@ public class Chapter21Test {
         int p1 = ps+4*8+1*8;
         // P2 = { age } // sizeof=8
         int p2 = ps+4*8+2*8;
-        EvalRisc5 R5 = TestRisc5.build("person", ps, 0, false);
+        EvalRisc5 R5 = TestRisc5.build("person21", ps, 0, false);
         R5.regs[riscv.A1] = 1;  // Index 1
         R5.st8(ps,3);           // Length
         R5.st8(ps+1*8,p0);
@@ -449,7 +462,7 @@ public class Chapter21Test {
         assertEquals(17+1,R5.ld8(p1));
         assertEquals(60+0,R5.ld8(p2));
 
-        EvalArm64 A5 = TestArm64.build("person", ps, 0, false);
+        EvalArm64 A5 = TestArm64.build("person21", ps, 0, false);
         A5.regs[arm.X1] = 1;  // Index 1
         A5.st8(ps, 3);
         A5.st8(ps+1*8,p0);
diff --git a/src/test/java/com/seaofnodes/simple/Chapter22Test.java b/src/test/java/com/seaofnodes/simple/Chapter22Test.java
new file mode 100644
index 00000000..a506004e
--- /dev/null
+++ b/src/test/java/com/seaofnodes/simple/Chapter22Test.java
@@ -0,0 +1,411 @@
+package com.seaofnodes.simple;
+
+import com.seaofnodes.isa.eval.EvalRisc5;
+
+import com.seaofnodes.isa.eval.EvalArm64;
+
+import com.seaofnodes.simple.codegen.RegAllocTestSupport.CheckedCodeGen;
+import com.seaofnodes.simple.codegen.CodeGen;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+
+import com.seaofnodes.simple.node.cpus.arm.arm;
+import com.seaofnodes.simple.node.cpus.riscv.riscv;
+import org.junit.Ignore;
+import org.junit.Test;
+import static org.junit.Assert.*;
+
+public class Chapter22Test {
+
+    @Test public void testNarrowCReturnsEmulated() {
+        String[] types = {"i8","u8","i16","u16","i32","u32","int"};
+        long[] values = {0xa5a5a5a500000000L,0xa5a5a5a50000007fL,0xa5a5a5a500000080L,
+            0xa5a5a5a500007fffL,0xa5a5a5a500008000L,0xa5a5a5a57fffffffL,
+            0xa5a5a5a580000000L,0xa5a5a5a5ffffffffL};
+        for( String target : new String[]{"arm","riscv"} )
+            for( int i=0; i<types.length; i++ ) {
+                String src = "{"+types[i]+"} c_narrow=\"C\"; return c_narrow();";
+                CodeGen code = new CheckedCodeGen(src).driver(CodeGen.Phase.Encoding,target,"SystemV");
+                var enc = code._encoding;
+                // Link the external call to a tiny independent native stub.
+                var call = code._stop.walk(n -> n instanceof com.seaofnodes.simple.node.CallNode ? n : null);
+                int start = enc._opStart[call._nid];
+                ((com.seaofnodes.simple.codegen.RIPRelSize)call).patch(enc,start,enc._opLen[call._nid],0x1000-start);
+                for( long value : values ) {
+                    long expected = switch(i) {
+                    case 0 -> (byte)value; case 1 -> value&255;
+                    case 2 -> (short)value; case 3 -> value&65535;
+                    case 4 -> (int)value; case 5 -> value&0xffffffffL;
+                    default -> value;
+                    };
+                    byte[] image = new byte[1<<16];
+                    byte[] bits = enc.bits();
+                    System.arraycopy(bits,0,image,0,bits.length);
+                    if( target.equals("arm") ) {
+                        EvalArm64 cpu = new EvalArm64(image,1<<15);
+                        // MOVZ X0,0x1100; LDR X0,[X0]; RET X30.
+                        cpu._pc = enc._opStart[code.link(code._main)._nid];
+                        cpu.st4(0x1000,0xd2822000); cpu.st4(0x1004,0xf9400000);
+                        cpu.st4(0x1008,0xd65f03c0);
+                        cpu.st8(0x1100,value);
+                        assertEquals(0,cpu.step(1000));
+                        assertEquals(0,cpu._pc);
+                        assertEquals(types[i],expected,cpu.regs[0]);
+                    } else {
+                        EvalRisc5 cpu = new EvalRisc5(image,1<<15);
+                        // AUIPC a0,0; LD a0,12(a0); RET.
+                        cpu._pc = enc._opStart[code.link(code._main)._nid];
+                        cpu.st4(0x1000,0x00000517); cpu.st4(0x1004,0x00c53503);
+                        cpu.st4(0x1008,0x00008067);
+                        // RV64 widens even u32 returns by sign-extending bit 31.
+                        cpu.st8(0x100c,i==6 ? value : (int)expected);
+                        assertEquals(0,cpu.step(1000));
+                        assertEquals(0,cpu._pc);
+                        assertEquals(types[i],expected,cpu.regs[riscv.A0]);
+                    }
+                }
+            }
+    }
+
+    @Test public void testNarrowCReturns() throws IOException {
+        String src = """
+            {i8} c_i8="C"; {u8} c_u8="C";
+            {i16} c_i16="C"; {u16} c_u16="C";
+            {i32} c_i32="C"; {u32} c_u32="C";
+            {int} c_i64="C";
+            val test_i8={->return c_i8();};
+            val test_u8={->return c_u8();};
+            val test_i16={->return c_i16();};
+            val test_u16={->return c_u16();};
+            val test_i32={->return c_i32();};
+            val test_u32={->return c_u32();};
+            val test_i64={->return c_i64();};
+            val test_cmp={->return c_i32()==-1;};
+            """;
+        for( String conv : new String[]{"SystemV","Win64"} )
+            TestC.run(src,conv,conv.equals("SystemV") ? "sysv_abi" : "ms_abi",
+                      "src/test/java/com/seaofnodes/simple/progs/c_returns.c",
+                      "build/objs/c_returns"+conv,"S","",-1);
+    }
+
+
+
+    @Test public void testReturnedFunctions() throws IOException {
+        for( String src : new String[]{"return {->42;};", "val f={->42;}; return f;", "return sys.io.p;"} )
+            for( String target : new String[]{"riscv","arm"} ) {
+                CodeGen code = new CheckedCodeGen(src).driver(CodeGen.Phase.Encoding,target,"SystemV").exportELF(null);
+                byte[] image = new byte[1<<16];
+                byte[] bits = code._encoding.bits();
+                System.arraycopy(bits,0,image,0,bits.length);
+                boolean library = src.contains("sys.io.p");
+                // u8[]: four-byte length followed by its bytes.
+                image[0x2000]=2; image[0x2004]='o'; image[0x2005]='k';
+                int entry = code._encoding._opStart[code.link(code._main)._nid];
+                if( target.equals("riscv") ) {
+                    EvalRisc5 cpu = new EvalRisc5(image,1<<15);
+                    cpu._pc = entry;
+                    assertEquals(0,cpu.step(1000));
+                    assertEquals(0,cpu._pc);
+                    cpu._pc = (int)cpu.regs[riscv.A0]; // Call the returned address.
+                    cpu.regs[riscv.A0] = 0x2000;
+                    assertEquals(0,cpu.step(1000));
+                    assertEquals(0,cpu._pc);
+                    if( library ) assertEquals("ok",cpu._stdout.toString());
+                    else assertEquals(42,cpu.regs[riscv.A0]);
+                } else {
+                    EvalArm64 cpu = new EvalArm64(image,1<<15);
+                    cpu._pc = entry;
+                    assertEquals(0,cpu.step(1000));
+                    assertEquals(0,cpu._pc);
+                    cpu._pc = (int)cpu.regs[0];
+                    cpu.regs[0] = 0x2000;
+                    assertEquals(0,cpu.step(1000));
+                    assertEquals(0,cpu._pc);
+                    if( library ) assertEquals("ok",cpu._stdout.toString());
+                    else assertEquals(42,cpu.regs[0]);
+                }
+            }
+        CodeGen unused = new CodeGen("({->42;}); return 0;").parse().iter().finalizeIR();
+        assertEquals(1,unused._stop.nIns());
+    }
+
+    @Test public void testReturnedFunctionsNative() throws IOException {
+        String src = "val factory={int x -> if(x) return {->42;}; return {->43;};}; val printer={->return sys.io.p;};";
+        String obj = "build/objs/funptr.o";
+        new CheckedCodeGen(src).driver(TestC.CPU_PORT,TestC.CALL_CONVENTION,obj);
+        assertEquals("ok",TestC.gcc(obj,"","src/test/java/com/seaofnodes/simple/progs/funptr.c",false,
+                                   "build/objs/funptr"+(TestC.OS.startsWith("Windows") ? ".exe" : "")));
+    }
+
+    @Test public void testRiscvRightShifts() {
+        // SRAI, SRLI, SRA, SRL: a0 = -32 shifted by 4.
+        int[] ops = {0x40455513,0x00455513,0x40b55533,0x00b55533};
+        for( int i=0; i<ops.length; i++ ) {
+            EvalRisc5 r5 = new EvalRisc5(new byte[1<<16],1<<15);
+            r5.st4(0,ops[i]);
+            r5.regs[riscv.A0] = -32;
+            r5.regs[riscv.A0+1] = 4;
+            assertEquals(0,r5.step(1));
+            assertEquals((i&1)==0 ? -2L : 0x0fff_ffff_ffff_fffeL,r5.regs[riscv.A0]);
+        }
+    }
+
+    @Test public void testRiscvPointerRelocation() {
+        CodeGen code = new CheckedCodeGen("return \"x\";").driver(CodeGen.Phase.Encoding,"riscv","SystemV");
+        var enc = code._encoding;
+        assertEquals(1,enc._bigCons.size());
+        var ptr = (com.seaofnodes.simple.node.cpus.riscv.TMPRISC)enc._bigCons.keySet().iterator().next();
+        int start = enc._opStart[ptr._nid];
+        for( int delta : new int[]{0x7ff,0x800,0xfff,0x1000,0x1800,-1,-0x800,-0x801} ) {
+            ptr.patch(enc,start,enc._opLen[ptr._nid],delta);
+            // Place the program above zero so backward targets are valid addresses.
+            byte[] image = new byte[1<<16];
+            System.arraycopy(enc.bits(),0,image,0x4000,enc._bits.size());
+            EvalRisc5 r5 = new EvalRisc5(image,1<<15);
+            r5._pc = 0x4000;
+            assertEquals(0,r5.step(100));
+            assertEquals(0x4000+start+delta,r5.regs[riscv.A0]);
+        }
+    }
+
+    @Test public void testSubZeroTypeError() {
+        try {
+            new CodeGen("return null-0;").driver(CodeGen.Phase.TypeCheck);
+            fail("Subtraction must reject null even when the other operand is zero");
+        } catch( Parser.ParseException e ) {
+            assertEquals("Cannot '-' null",e.getMessage());
+        }
+    }
+
+    @Test public void testInfiniteReturn() {
+        String src = "struct S { int i; }; !S !s = new S; while(1) s.i++; return s.i;";
+        testCPU(src,"x86_64_v2","SystemV",0,"return Top;");
+        testCPU(src,"riscv","SystemV",0,"return Top;");
+        testCPU(src,"arm","SystemV",0,"return Top;");
+    }
+
+
+    @Test @Ignore
+    public void testJig() throws IOException {
+        String src = Files.readString(Path.of("src/test/java/com/seaofnodes/simple/progs/jig.smp"));
+        //String src = Files.readString(Path.of("docs/examples/BubbleSort.smp"));
+        testCPU(src,"x86_64_v2", "Win64"  ,-1,null);
+        testCPU(src,"riscv"    , "SystemV",-1,null);
+        testCPU(src,"arm"      , "SystemV",-1,null);
+    }
+
+    static CodeGen testCPU( String src, String cpu, String os, int spills, String stop ) {
+        CodeGen code = new CheckedCodeGen(src).driver(CodeGen.Phase.Encoding,cpu,os);
+        SpillStats.record(code,"Chapter22",cpu,os);
+        SpillStats.checkSpills(spills,code._regAlloc._spillScaled);
+        if( stop != null )
+            assertEquals(stop, code._stop.toString());
+        return code;
+    }
+
+
+    static int testCPUSize( String src, String cpu, String os, int spills, String stop ) {
+        return testCPU(src,cpu,os,spills,stop)._encoding._bits.size();
+    }
+
+    // Should not fold away
+    @Test public void testSextFail() throws IOException {
+        String src = """
+struct Person { i32 age;};
+!Person !p = new Person;
+p.age = (arg<<17)>>17;
+return 0;
+""";
+        assertEquals(46, testCPUSize(src, "x86_64_v2","Win64",2,"return 0;"));
+        assertEquals(60, testCPUSize(src, "riscv","SystemV",4,"return 0;"));
+        assertEquals(56, testCPUSize(src, "arm","SystemV",4,"return 0;"));
+
+        // do assertEquals here
+        EvalRisc5 R5 = TestRisc5.build("sext_str_not_fold_away", 0, 4, false);
+        int trap = R5.step(100);
+        assertEquals(0,trap);
+
+        EvalArm64 A5 = TestArm64.build("sext_str_not_fold_away", 0, 4, false);
+        trap = A5.step(100);
+        assertEquals(0,trap);
+
+    }
+
+    // Should not fold away
+    @Test public void testSextFail2() throws IOException {
+        String src = """
+
+                struct Person { i32 age;};
+                !Person !p = new Person;
+                p.age = (arg<<48)>>48;
+                return 0;
+        """;
+
+        EvalRisc5 R5 = TestRisc5.build("sext_str_not_fold_away_2", 0, 4, false);
+        int trap = R5.step(100);
+        assertEquals(0,trap);
+
+        EvalArm64 A5 = TestArm64.build("sext_str_not_fold_away_2", 0, 4, false);
+        int trap_arm = A5.step(100);
+        assertEquals(0,trap_arm);
+
+        assertEquals(46, testCPUSize(src, "x86_64_v2","Win64",2,"return 0;"));
+        assertEquals(60, testCPUSize(src, "riscv","SystemV",4,"return 0;"));
+        assertEquals(56, testCPUSize(src, "arm","SystemV",4,"return 0;"));
+
+    }
+
+    // Should fold away
+    @Test public void testSextSuccess() throws IOException {
+        String src = """
+// Should fold away sign extend
+struct Person { i8 age;};
+!Person !p = new Person;
+p.age = (arg<<48)>>48;
+return 0;
+       """;
+
+        EvalRisc5 R5 = TestRisc5.build("sext_str_fold_away", 0, 5, false);
+        int trap = R5.step(100);
+        assertEquals(0,trap);
+
+        EvalArm64 A5 = TestArm64.build("sext_str_fold_away", 0, 5, false);
+        int trap_arm = A5.step(100);
+        assertEquals(0,trap_arm);
+
+        assertEquals(41, testCPUSize(src, "x86_64_v2","Win64",2,"return 0;"));
+        assertEquals(56, testCPUSize(src, "riscv","SystemV",5,"return 0;"));
+        assertEquals(52, testCPUSize(src, "arm","SystemV",5,"return 0;"));
+        // do assertEquals here
+    }
+
+
+    // Int now is changed to 4 bytes.
+    @Test public void testPerson() throws IOException {
+        String person = "6\n";
+        TestC.run("person", person, 0);
+
+        // Memory layout starting at PS:
+        int ps = 1<<16;         // Person array pointer starts at heap start
+        // Person[3] = { len,pad,P0,P1,P2 }; // sizeof = 4*8
+        // P0 = { age } // sizeof=8
+        int p0 = ps+4*8+0*8;
+        // P1 = { age } // sizeof=8
+        int p1 = ps+4*8+1*8;
+        // P2 = { age } // sizeof=8
+        int p2 = ps+4*8+2*8;
+        EvalRisc5 R5 = TestRisc5.build("person", ps, 0, false);
+        R5.regs[riscv.A1] = 1;  // Index 1
+        R5.st8(ps,3);           // Length
+        R5.st8(ps+1*8,p0);
+        R5.st8(ps+2*8,p1);
+        R5.st8(ps+3*8,p2);
+        R5.st8(p0, 5); // age= 5
+        R5.st8(p1,17); // age=17
+        R5.st8(p2,60); // age=60
+
+        int trap = R5.step(100);
+        assertEquals(0,trap);
+        assertEquals( 5+0,R5.ld8(p0));
+        assertEquals(17+1,R5.ld8(p1));
+        assertEquals(60+0,R5.ld8(p2));
+
+        EvalArm64 A5 = TestArm64.build("person", ps, 0, false);
+        A5.regs[arm.X1] = 1;  // Index 1
+        A5.st8(ps, 3);
+        A5.st8(ps+1*8,p0);
+        A5.st8(ps+2*8,p1);
+        A5.st8(ps+3*8,p2);
+        A5.st8(p0, 5); // age= 5
+        A5.st8(p1,17); // age=17
+        A5.st8(p2,60); // age=60
+
+        int trap_arm = A5.step(100);
+        assertEquals(0,trap_arm);
+        assertEquals( 5+0, A5.ld8(p0));
+        assertEquals(17+1, A5.ld8(p1));
+        assertEquals(60+0, A5.ld8(p2));
+    }
+
+    @Test
+    public void testCoRecur() {
+        String src = """
+struct A { !B? !b; !C? !c; i64 ax; val az = x*2; };
+struct B { !A? !a; !C? !c; f32 bx; val bz = x*3; };
+struct C { !A? !a; !B? !b; f64 cx; val cz = x*x; };
+!A !aa = new A{ ax=17; };
+!B !bb = new B{ bx=3.14; a = aa; };
+!C !cc = new C{ cx=2.73; a = aa; b = bb; };
+aa.b = bb;
+aa.c = cc;
+bb.c = cc;
+val x = 5; // aa.az; // Error to self-define forward ref
+return cc.cz;
+""";
+        CodeGen code = new CodeGen(src).driver(CodeGen.Phase.TypeCheck);
+        assertEquals("return 25;", code._stop.toString());
+        assertEquals("25", Eval2.eval(code, 0));
+    }
+
+    @Test
+    public void testHelloWorld() throws IOException {
+        String src = Files.readString(Path.of("src/test/java/com/seaofnodes/simple/progs/helloWorld.smp"));
+        TestC.run(src,TestC.CALL_CONVENTION,null,null,"build/objs/helloWorld","","Hello, World!",0);
+
+        // Evaluate on RISC5 emulator
+        EvalRisc5 R5 = TestRisc5.build("helloWorld", 0, 2, false);
+        int trap = R5.step(100);
+        assertEquals(0,trap);
+        assertEquals(0,R5.regs[riscv.A0]);
+        assertEquals("Hello, World!",R5._stdout.toString());
+
+        // Evaluate on ARM emulator
+        EvalArm64 arm = TestArm64.build("helloWorld", 0, 2, false);
+        trap = arm.step(100);
+        assertEquals(0,trap);
+        assertEquals(0,arm.regs[0]);
+        assertEquals("Hello, World!",arm._stdout.toString());
+    }
+
+    @Test
+    public void testFinalArray() {
+        String src = """
+int N=4;
+i32[] !is = new i32[N];
+for( int i=0; i<N; i++ )
+    is[i] = i*i;
+val sum = { i32[~] is ->  // final array
+    int sum=0;
+    for( int i=0; i<is#; i++ )
+        sum += is[i];
+    return sum;
+};
+return sum(is);
+""";
+        CodeGen code = new CodeGen(src).driver(CodeGen.Phase.TypeCheck);
+        assertEquals("return Phi(Loop,0,(Phi_sum+.[]));", code._stop.toString());
+        assertEquals("14", Eval2.eval(code, 0));
+    }
+
+
+    @Test @Ignore
+    public void testEcho() throws IOException {
+        String src = Files.readString(Path.of("src/test/java/com/seaofnodes/simple/progs/echo.smp"));
+        TestC.run(src,TestC.CALL_CONVENTION,null,null,"build/objs/echo","","",0);
+
+        // Evaluate on RISC5 emulator
+        EvalRisc5 R5 = TestRisc5.build("echo", 0, 2, false);
+        int trap = R5.step(100);
+        assertEquals(0,trap);
+        assertEquals(0,R5.regs[riscv.A0]);
+
+        // Evaluate on ARM emulator
+        EvalArm64 arm = TestArm64.build("echo", 0, 2, false);
+        trap = arm.step(100);
+        assertEquals(0,trap);
+        assertEquals(0,arm.regs[0]);
+    }
+
+
+}
diff --git a/src/test/java/com/seaofnodes/simple/CompoundAssignmentTest.java b/src/test/java/com/seaofnodes/simple/CompoundAssignmentTest.java
index 8131c95f..e2d822d0 100644
--- a/src/test/java/com/seaofnodes/simple/CompoundAssignmentTest.java
+++ b/src/test/java/com/seaofnodes/simple/CompoundAssignmentTest.java
@@ -88,7 +88,7 @@ public class CompoundAssignmentTest {
     }
 
     private static void check(String src, long arg, long expected) {
-        var code = new CodeGen(src).parse().iter().typeCheck();
+        var code = new CodeGen(src).driver(CodeGen.Phase.TypeCheck);
         assertEquals(src, Long.toString(expected), Eval2.eval(code, arg));
     }
 }
diff --git a/src/test/java/com/seaofnodes/simple/Eval2.java b/src/test/java/com/seaofnodes/simple/Eval2.java
index f39750c2..bbf88f1a 100644
--- a/src/test/java/com/seaofnodes/simple/Eval2.java
+++ b/src/test/java/com/seaofnodes/simple/Eval2.java
@@ -114,6 +114,7 @@ public abstract class Eval2 {
 
     public static String eval( CodeGen code, long arg ) { return eval(code,arg,1000); }
     public static String eval( CodeGen code, long arg, int timeout ) {
+        if( code._start.uctrl()==null ) return ""; // The empty program
         SB trace = null; // new SB(); // TRACE, set to null for off, new SB() for on
         // Force local scheduling phase
         code.driver(CodeGen.Phase.LocalSched);
@@ -297,9 +298,9 @@ public abstract class Eval2 {
     // 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);  }
+    static long   x( Node n ) { Object d = F.get(n); return d==null ? 0 : (Long)d;  }
     // Fetch and unbox as primitive double
-    static double d( Node n ) { Object d = F.get(n); return d==null ? 0 : (Double)F.get(n);  }
+    static double d( Node n ) { Object d = F.get(n); return d==null ? 0 : (Double)d;  }
     // Fetch and unbox a function constant
     static TypeFunPtr tfp(Node n) { return (TypeFunPtr)F.get(n); }
     // Fetch and unbox a closure
@@ -355,10 +356,19 @@ public abstract class Eval2 {
     }
 
     private static Object load( LoadNode ld ) {
-        TypeMemPtr tmp = (TypeMemPtr)ld.ptr()._type;
-        Object[] fs = (Object[])val(ld.ptr());
+        Object f = val(ld.ptr());
+        // Check for dense constant array
+        if( f instanceof TypeMemPtr tmp ) {
+            assert tmp._obj._con != TypeConAry.BOT;
+            if( ld._name.equals("#") )
+                return (long)tmp._obj._con.len();
+            int idx = offToIdx(x(ld.off()),tmp._obj);
+            return tmp._obj._con.at(idx);
+        }
+        Object[] fs = (Object[])f;
         if( ld._name.equals("#") )
             return (long)fs.length;
+        TypeMemPtr tmp = (TypeMemPtr)ld.ptr()._type;
         int idx = tmp._obj.isAry()
             ? offToIdx(x(ld.off()),tmp._obj)
             : tmp._obj.find(ld._name);
diff --git a/src/test/java/com/seaofnodes/simple/LiteralTest.java b/src/test/java/com/seaofnodes/simple/LiteralTest.java
new file mode 100644
index 00000000..0f6e43a4
--- /dev/null
+++ b/src/test/java/com/seaofnodes/simple/LiteralTest.java
@@ -0,0 +1,65 @@
+package com.seaofnodes.simple;
+
+import com.seaofnodes.simple.codegen.CodeGen;
+import com.seaofnodes.simple.type.TypeConAryB;
+import com.seaofnodes.simple.type.TypeInteger;
+import com.seaofnodes.simple.type.TypeMemPtr;
+import org.junit.Test;
+import static org.junit.Assert.*;
+
+public class LiteralTest {
+    private static final String[] ESCAPES = {"\\0", "\\n", "\\t", "\\r", "\\\\", "\\\"", "\\'"};
+    private static final int[] VALUES = {0, 10, 9, 13, 92, 34, 39};
+
+    @Test public void testStringEscapes() {
+        for (int i = 0; i < ESCAPES.length; i++)
+            assertString(ESCAPES[i], new byte[]{(byte)VALUES[i]});
+        assertString("a\\\"b\\\\c\\0d", new byte[]{97, 34, 98, 92, 99, 0, 100});
+        assertString("", new byte[]{});
+        assertString("plain", new byte[]{112, 108, 97, 105, 110});
+    }
+
+    private static void assertString(String text, byte[] expected) {
+        var code = new CodeGen("return \"" + text + "\";").driver(CodeGen.Phase.TypeCheck);
+        TypeMemPtr ptr = (TypeMemPtr)code.expr()._type;
+        TypeConAryB bytes = (TypeConAryB)ptr._obj._con;
+        assertArrayEquals(text, expected, bytes._ary);
+    }
+
+    @Test public void testCharacterEscapes() {
+        for (int i = 0; i < ESCAPES.length; i++)
+            assertCharacter(ESCAPES[i], VALUES[i]);
+        assertCharacter("A", 65);
+    }
+
+    private static void assertCharacter(String text, int expected) {
+        var code = new CodeGen("return '" + text + "';").driver(CodeGen.Phase.TypeCheck);
+        assertEquals(text, expected, ((TypeInteger)code.expr()._type).value());
+    }
+
+    @Test public void testMalformedStrings() {
+        assertBadLiteral("return \"\\q\";", "Unknown string escape");
+        assertBadLiteral("return \"abc", "Unclosed string");
+        assertBadLiteral("return \"abc\\", "Unclosed string");
+        // The quote closes the string at EOF; the missing token is the semicolon.
+        assertBadLiteral("return \"plain\"", ";");
+    }
+
+    @Test public void testMalformedCharacters() {
+        assertBadLiteral("return '\\q';", "Unknown character escape");
+        assertBadLiteral("return '", "Unclosed character");
+        assertBadLiteral("return '\\", "Unclosed character");
+        assertBadLiteral("return '';", "Syntax error");
+        assertBadLiteral("return 'ab';", "Syntax error");
+        assertBadLiteral("return 'a", "Syntax error");
+    }
+
+    private static void assertBadLiteral(String src, String message) {
+        try {
+            new CodeGen(src).parse();
+            fail("Accepted malformed literal: " + src);
+        } catch (Parser.ParseException e) {
+            assertTrue(e.getMessage(), e.getMessage().contains(message));
+        }
+    }
+}
diff --git a/src/test/java/com/seaofnodes/simple/MemoryEncodingTest.java b/src/test/java/com/seaofnodes/simple/MemoryEncodingTest.java
index 7cdf217b..700e5344 100644
--- a/src/test/java/com/seaofnodes/simple/MemoryEncodingTest.java
+++ b/src/test/java/com/seaofnodes/simple/MemoryEncodingTest.java
@@ -9,6 +9,7 @@ import com.seaofnodes.simple.codegen.RegAllocTestSupport;
 import com.seaofnodes.simple.node.*;
 import com.seaofnodes.simple.node.cpus.arm.arm;
 import com.seaofnodes.simple.node.cpus.riscv.riscv;
+import com.seaofnodes.simple.type.TypeMemPtr;
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
@@ -65,7 +66,7 @@ public class MemoryEncodingTest {
             """
         };
         for( int p=0; p<sources.length; p++ ) {
-            CodeGen code=new CodeGen(sources[p]).parse().iter();
+            CodeGen code=new CodeGen(sources[p]).parse().iter().finalizeIR();
             if( p==0 ) assertNull(code._stop.walk(n ->
                 n instanceof LoadNode ld && ld.ptr() instanceof ProjNode ptr &&
                 ptr.in(0) instanceof NewNode nn &&
@@ -152,8 +153,9 @@ public class MemoryEncodingTest {
             assertNotNull(code._stop.walk(n -> {
                 if( n instanceof MemMergeNode mem &&
                     mem.in(0) instanceof CProjNode exit && exit.in(0) instanceof NeverNode ) {
-                    assertTrue(mem.alias(2) instanceof MemPhiNode);
-                    assertTrue(mem.alias(3) instanceof MemPhiNode);
+                    var fields = ((TypeMemPtr)Parser.TYPES.get("S"))._obj._fields;
+                    assertTrue(mem.alias(fields[0]._alias) instanceof MemPhiNode);
+                    assertTrue(mem.alias(fields[1]._alias) instanceof MemPhiNode);
                     return mem;
                 }
                 return null;
@@ -173,7 +175,7 @@ public class MemoryEncodingTest {
                 c.append("if(memory(").append(arg).append(")!=").append(expected(p,arg)).append("LL) return ").append(arg+1).append(";\n");
             c.append("return 0;\n}\n");
             Files.writeString(Path.of(file+".c"),c);
-            TestC._run("val memory = { int arg -> "+SOURCES[p]+" };",
+            TestC.run("val memory = { int arg -> "+SOURCES[p]+" };",
                 TestC.CALL_CONVENTION,"",file+".c",file,"S","",-1);
         }
     }
diff --git a/src/test/java/com/seaofnodes/simple/MutabilityTest.java b/src/test/java/com/seaofnodes/simple/MutabilityTest.java
index baf4e252..51e31a17 100644
--- a/src/test/java/com/seaofnodes/simple/MutabilityTest.java
+++ b/src/test/java/com/seaofnodes/simple/MutabilityTest.java
@@ -6,12 +6,12 @@ import com.seaofnodes.simple.codegen.CodeGen;
 
 public class MutabilityTest {
     private static void ok(String src, String result) {
-        var code = new CodeGen(src).parse().iter().typeCheck();
+        var code = new CodeGen(src).driver(CodeGen.Phase.TypeCheck);
         assertEquals(result,Eval2.eval(code,0));
     }
     private static void bad(String src) {
         try {
-            new CodeGen(src).parse().iter().typeCheck();
+            new CodeGen(src).driver(CodeGen.Phase.TypeCheck);
         } catch( RuntimeException expected ) {
             String msg = expected.getMessage();
             assertTrue("Expected a permission error, got: "+expected,
diff --git a/src/test/java/com/seaofnodes/simple/PhaseTest.java b/src/test/java/com/seaofnodes/simple/PhaseTest.java
index d890a537..885889a8 100644
--- a/src/test/java/com/seaofnodes/simple/PhaseTest.java
+++ b/src/test/java/com/seaofnodes/simple/PhaseTest.java
@@ -27,13 +27,13 @@ public class PhaseTest {
         code.driver(Phase.LoopTree);
         assertEquals(Phase.LoopTree,code._phase);
         code.driver(Phase.LocalSched);
-        assertEquals("Parse Iter TypeCheck LoopTree Schedule LocalSched",String.join(" ",phases));
+        assertEquals("Parse Iter FinalizeIR TypeCheck LoopTree Schedule LocalSched",String.join(" ",phases));
         assertEquals("45",Eval2.eval(code,10));
     }
 
     @Test public void testResumeMachineCompilation() {
         CodeGen staged = new CodeGen(SRC).driver(Phase.TypeCheck);
-        staged.driver(Phase.InstSelect,"x86_64_v2","SystemV");
+        staged.driver(Phase.Select,"x86_64_v2","SystemV");
         staged.driver(Phase.Encoding,"x86_64_v2","SystemV");
         byte[] bits = staged._encoding._bits.toByteArray();
         CodeGen direct = new CodeGen(SRC).driver(Phase.Encoding,"x86_64_v2","SystemV");
diff --git a/src/test/java/com/seaofnodes/simple/SchedulerTest.java b/src/test/java/com/seaofnodes/simple/SchedulerTest.java
index a388d8c3..ca211c60 100644
--- a/src/test/java/com/seaofnodes/simple/SchedulerTest.java
+++ b/src/test/java/com/seaofnodes/simple/SchedulerTest.java
@@ -51,7 +51,7 @@ int i=v.f;
 if (arg) v.f=1;
 return i;
 """);
-        code.parse();//.iter();
+        code.parse();//.iter().finalizeIR();
         var eval = new Evaluator(code._stop);
         assertEquals(2L, eval.evaluate(1, 10));
     }
@@ -66,7 +66,7 @@ struct S {
 if(arg) v0.f=1;
 return v0;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         var eval = new Evaluator(code._stop);
         assertObj(eval.evaluate(0, 10), "S", 0L);
         assertObj(eval.evaluate(1, 10), "S", 1L);
@@ -85,7 +85,7 @@ i=v.f;
 if (arg) v.f=1;
 return i;
 """);
-        code.parse().iter();
+        code.parse().iter().finalizeIR();
         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/Simple.java b/src/test/java/com/seaofnodes/simple/Simple.java
index c496ea90..69fbabc9 100644
--- a/src/test/java/com/seaofnodes/simple/Simple.java
+++ b/src/test/java/com/seaofnodes/simple/Simple.java
@@ -16,9 +16,10 @@ public class Simple {
 
     static final int DUMP_AFTER_PARSE = 1<<Phase.Parse.ordinal();
     static final int DUMP_AFTER_ITER = 1<<Phase.Iter.ordinal();
+    static final int DUMP_AFTER_FINALIZE_IR = 1<<Phase.FinalizeIR.ordinal();
     static final int DUMP_AFTER_TYPE_CHECK = 1<<Phase.TypeCheck.ordinal();
     static final int DUMP_AFTER_LOOP_TREE = 1<<Phase.LoopTree.ordinal();
-    static final int DUMP_AFTER_INSTR_SELECT = 1<<Phase.InstSelect.ordinal();
+    static final int DUMP_AFTER_SELECT = 1<<Phase.Select.ordinal();
     static final int DUMP_AFTER_GCM = 1<<Phase.Schedule.ordinal();
     static final int DUMP_AFTER_LOCAL_SCHED = 1<<Phase.LocalSched.ordinal();
     static final int DUMP_AFTER_REG_ALLOC = 1<<Phase.RegAlloc.ordinal();
@@ -31,33 +32,31 @@ public class Simple {
 
     static final int DUMP_DISASSEMBLE        = 1<<31;
 
-    static String system_cpu = null;
-    static String system_abi = null;
-
     static void usage() {
         System.out.println(
 """
-simple <input-file> [options] [--eval|--run ...]
+simple [options] <input-file> ...args...
 Options:
-  --dump                     - dump final intermediate representation
+  --dump                   - dump final intermediate representation
   --dump-after-parse           - dump intermediate representation after parsing
   --dump-after-iter            - dump intermediate representation after Iter
+  --dump-after-finalize-ir     - dump intermediate representation after FinalizeIR
   --dump-after-type-check      - dump intermediate representation after type checking
   --dump-after-loop-tree       - dump intermediate representation after loop-tree construction
-  --dump-after-instr-select    - dump intermediate representation after instruction selection
+  --dump-after-select          - dump intermediate representation after instruction selection
   --dump-after-gcm             - dump intermediate representation after GCM
   --dump-after-local-sched     - dump intermediate representation after local scheduling
   --dump-after-reg-alloc       - dump intermediate representation after register allocation
   --dump-after-encode          - dump intermediate representation after encoding
   --dump-after-all             - dump intermediate representation after all passes
-  -S                         - dump generated assembler code
-  --eval ...                 - evaluate the compiled code in emulator
-  --run ...                  - run the compiled code natively
-  --dump-size                - print the size of generated code
-  --dump-time                - print compilation and execution times
-  --cpu <cpu-name>           - use specific CPU (x86_64_v2, riscv, arm)
-  --abi <abi-name>           - use speific ABI variant (SystemV)
-  --target                   - print native CPU and ABI
+  -S                       - dump generated assembler code
+  --eval                   - evaluate the compiled code in emulator
+  --run                    - run the compiled code natively; this is the default
+  --dump-size              - print the size of generated code
+  --dump-time              - print compilation and execution times
+  --cpu <cpu-name>         - use specific CPU (x86_64_v2, riscv, arm)
+  --abi <abi-name>         - use speific ABI variant (SystemV)
+  --target                 - print native CPU and ABI
   --version
   --help
 """
@@ -65,20 +64,17 @@ Options:
         System.exit(0);
     }
 
-    static void bad_usage() {
-        System.err.println("ERROR: Invalid usage (use --help)");
+    static void bad_usage() { bad("Invalid usage (use --help)"); }
+    static RuntimeException bad(String err) {
+        System.err.println("ERROR: "+err);
         System.exit(1);
+        return new RuntimeException(err);
     }
 
     static void target() {
-        if (system_cpu == null || system_abi == null) {
-            System.err.println("ERROR: Unknown target");
-            System.exit(1);
-        }
-        System.out.print(system_cpu);
+        System.out.print(TestC.CPU_PORT);
         System.out.print("-");
-        System.out.println(system_abi);
-        System.exit(0);
+        System.out.println(TestC.CALL_CONVENTION);
     }
 
     static void dump(CodeGen code, int dump, int pass) {
@@ -105,9 +101,8 @@ Options:
 
     public static void main(String[] args) throws Exception {
         String input_filename = null;
-        boolean use_stdin = false;
         boolean do_eval = false;
-        boolean do_run = false;
+        boolean do_run = true;
         boolean do_codegen = false;
         boolean do_print_size = false;
         boolean do_print_time = false;
@@ -117,83 +112,69 @@ Options:
         String cpu = null;
         String abi = null;
 
-        // TODO: autodetect
-        system_cpu = "x86_64_v2";
-        system_abi = "SystemV";
-
         // Parse command line
-loop:   for (int i = 0; i < args.length; i++) {
+        int i; for( i = 0; i < args.length; i++ ) {
             String arg = args[i];
-            if (arg.charAt(0) == '-') {
-                switch (arg) {
-                    case "-":                         use_stdin = true; break;
-                    case "--dump":                    dump |= DUMP_FINAL; break;
-                    case "--dump-after-parse":          dump |= DUMP_AFTER_PARSE; break;
-                    case "--dump-after-iter":           dump |= DUMP_AFTER_ITER; break;
-                    case "--dump-after-type-check":     dump |= DUMP_AFTER_TYPE_CHECK; break;
-                    case "--dump-after-loop-tree":      dump |= DUMP_AFTER_LOOP_TREE; break;
-                    case "--dump-after-instr-select":   dump |= DUMP_AFTER_INSTR_SELECT; break;
-                    case "--dump-after-gcm":            dump |= DUMP_AFTER_GCM; break;
-                    case "--dump-after-local-sched":    dump |= DUMP_AFTER_LOCAL_SCHED; break;
-                    case "--dump-after-reg-alloc":      dump |= DUMP_AFTER_REG_ALLOC; break;
-                    case "--dump-after-encode":         dump |= DUMP_AFTER_ENCODE; break;
-                    case "--dump-after-all":            dump |= DUMP_AFTER_ALL; break;
-                    case "-S":                        dump |= DUMP_DISASSEMBLE; break;
-                    case "--eval":                    do_eval = true; first_arg = i + 1; break loop;
-                    case "--run":                     do_run = true; first_arg = i + 1; break loop;
-                    case "--dump-size":               do_print_size = true; break;
-                    case "--dump-time":               do_print_time = true; break;
-                    case "--cpu":                     if (cpu != null
-                                                       || i + 1 >= args.length
-                                                       || args[i + 1].charAt(0) == '-') bad_usage();
-                                                      cpu = args[i + 1];
-                                                      i++;
-                                                      break;
-                    case "--abi":                     if (abi != null
-                                                       || i + 1 >= args.length
-                                                       || args[i + 1].charAt(0) == '-') bad_usage();
-                                                      abi = args[i + 1];
-                                                      i++;
-                                                      break;
-                    case "--target":                  target();
-                    case "--version":                 throw Utils.TODO();
-                    case "--help":                    usage();
-                    default:                          bad_usage();
-                }
-            } else {
-                if (input_filename != null || use_stdin) bad_usage();
+            if( arg.charAt(0) != '-' ) {
                 input_filename = arg;
+                break;
             }
-        }
 
-        if (input_filename == null && !use_stdin) {
-            System.err.println("ERROR: no input file' (use --help)");
-            System.exit(1);
+            switch (arg) {
+            case "-":                         input_filename=""; break;
+            case "--dump":                    dump |= DUMP_FINAL; break;
+            case "--dump-after-parse":          dump |= DUMP_AFTER_PARSE; break;
+            case "--dump-after-finalize-ir":    dump |= DUMP_AFTER_FINALIZE_IR; break;
+            case "--dump-after-iter":           dump |= DUMP_AFTER_ITER; break;
+            case "--dump-after-type-check":     dump |= DUMP_AFTER_TYPE_CHECK; break;
+            case "--dump-after-loop-tree":      dump |= DUMP_AFTER_LOOP_TREE; break;
+            case "--dump-after-select":         dump |= DUMP_AFTER_SELECT; break;
+            case "--dump-after-gcm":            dump |= DUMP_AFTER_GCM; break;
+            case "--dump-after-local-sched":    dump |= DUMP_AFTER_LOCAL_SCHED; break;
+            case "--dump-after-reg-alloc":      dump |= DUMP_AFTER_REG_ALLOC; break;
+            case "--dump-after-encode":         dump |= DUMP_AFTER_ENCODE; break;
+            case "--dump-after-all":            dump |= DUMP_AFTER_ALL; break;
+            case "-S":                        dump |= DUMP_DISASSEMBLE; break;
+            case "--eval":                    do_eval = true ; do_run = false; break;
+            case "--run":                     do_run  = true ; break;
+            case "--norun":                   do_run  = false; break;
+            case "--dump-size":               do_print_size = true; break;
+            case "--dump-time":               do_print_time = true; break;
+            case "--cpu":                     if (cpu != null || i + 1 >= args.length || args[i + 1].charAt(0) == '-') bad_usage();
+                                              cpu = args[++i];
+                                              break;
+            case "--abi":                     if (abi != null || i + 1 >= args.length || args[i + 1].charAt(0) == '-') bad_usage();
+                                              abi = args[++i];
+                                              break;
+            case "--target":                  target(); break;
+            case "--version":                 throw Utils.TODO();
+            case "--help":                    usage();
+            default:                          bad_usage();
+            }
         }
 
+        if (input_filename == null) throw bad("no input file' (use --help)");
+        if( !input_filename.isEmpty() && !input_filename.endsWith(".smp") )
+            throw bad("File extension must be .smp");
+        String base = input_filename.substring(0,input_filename.length()-4);
+
         if (do_run || (dump & DUMP_DISASSEMBLE) != 0 || do_print_size) {
-            if (cpu == null) cpu = system_cpu;
-            if (abi == null) abi = system_abi;
-            if (cpu == null || abi == null) {
-                System.err.println("ERROR: Cannot compile for unknown target");
-                System.exit(1);
-            }
+            if (cpu == null) cpu = TestC.CPU_PORT;
+            if (abi == null) abi = TestC.CALL_CONVENTION;
             do_codegen = true;
         }
 
         // Read input file
         try {
-            src = use_stdin ? getInput() : Files.readString(Path.of(input_filename));
-        } catch(IOException e) {
-            System.err.println("ERROR: Cannot read input file");
-            System.exit(1);
-        }
+            src = input_filename.isEmpty() ? getInput() : Files.readString(Path.of(input_filename));
+        } catch( IOException e ) { throw bad("Cannot read input file: "+input_filename);  }
 
         // Compilation pipeline
         CodeGen code = new CodeGen(src);
 
         code.driver(do_codegen ? Phase.Encoding : Phase.LocalSched,
                     do_codegen ? cpu : null, abi, dump);
+        if( do_codegen ) code.exportELF(base+".o");
 
         dump(code, dump, DUMP_FINAL);
 
@@ -202,7 +183,7 @@ loop:   for (int i = 0; i < args.length; i++) {
         }
 
         if (do_print_size) {
-             System.out.println(String.format("Code Size: %d", code._encoding._bits.size()));
+             System.out.printf( "Code Size: %d%n", code._encoding._bits.size());
         }
 
         if (do_print_time) {
@@ -212,19 +193,19 @@ loop:   for (int i = 0; i < args.length; i++) {
         if (do_eval) {
             // TODO: Support for evaluation of functions with different argument numbers and types
             long t = System.currentTimeMillis();
-            long arg = (first_arg < args.length) ? Integer.valueOf(args[first_arg]) : 0;
+            long arg = (i+1 < args.length) ? Integer.parseInt(args[i+1]) : 0;
             System.out.println(Eval2.eval(code, arg, 100000));
             if (do_print_time) {
-                System.out.println(String.format("EXECUTION TIME:             %.3f sec",
-                    (System.currentTimeMillis() - t) / 1e3));
+                System.out.printf( "EXECUTION TIME:             %.3f sec%n",
+                    (System.currentTimeMillis() - t) / 1e3);
             }
-        } else if (do_run) {
-            if (cpu != system_cpu || abi != system_abi) {
-                System.err.println("ERROR: cannot run code on not native target");
-                System.exit(1);
-            }
-
-            throw Utils.TODO();
+        }
+        if (do_run) {
+            if ( !TestC.CPU_PORT.equals( cpu ) || !TestC.CALL_CONVENTION.equals( abi ) )
+                throw bad("cannot run code on not native target");
+            String exe = TestC.OS.startsWith("Windows") ? base+".exe" : base;
+            String result = com.seaofnodes.simple.TestC.gcc(base+".o", null, null, true, exe);
+            System.out.print(result);
         }
     }
 }
diff --git a/src/test/java/com/seaofnodes/simple/SpillStats.java b/src/test/java/com/seaofnodes/simple/SpillStats.java
index 318a6e33..82cffef8 100644
--- a/src/test/java/com/seaofnodes/simple/SpillStats.java
+++ b/src/test/java/com/seaofnodes/simple/SpillStats.java
@@ -26,6 +26,13 @@ public class SpillStats extends RunListener {
                            code._regAlloc._spills+","+code._regAlloc._spillScaled);
     }
 
+    // The same native helpers serve old and new program cohorts.
+    public static void recordNative(CodeGen code, String cpu, String abi) {
+        String cohort = ACTIVE!=null && ACTIVE._test.getTestClass()==Chapter22Test.class
+            ? "Chapter22" : "Chapter21";
+        record(code,cohort,cpu,abi);
+    }
+
     // Keep running every CPU and native result check when measuring quality.
     // A changed golden still makes spill-stats fail at the end.
     public static void checkSpills(int expected, int actual) {
@@ -39,7 +46,7 @@ public class SpillStats extends RunListener {
     }
 
     public static void main(String[] args) throws ClassNotFoundException {
-        if( args.length==0 ) args = new String[]{"Chapter20Test","Chapter21Test","Chapter21AllocTest","BrainFuckTest","MergeSortTest"};
+        if( args.length==0 ) args = new String[]{"Chapter20Test","Chapter21Test","Chapter21AllocTest","Chapter22Test","BrainFuckTest","MergeSortTest"};
         Class<?>[] tests = new Class<?>[args.length];
         for( int i=0; i<args.length; i++ )
             tests[i] = Class.forName("com.seaofnodes.simple."+args[i]);
@@ -48,7 +55,8 @@ public class SpillStats extends RunListener {
         junit.addListener(ACTIVE);
         Result result = junit.run(tests);
         boolean passed = result.wasSuccessful() && ACTIVE._qualityFailures==0;
-        if( !passed ) System.out.println("FAILED test run: totals are not a complete comparison.");
+        if( !result.wasSuccessful() ) System.out.println("FAILED test run: totals are not a complete comparison.");
+        else if( !passed ) System.out.println("Spill expectations differ; allocation and runtime checks passed.");
         System.out.println("cohort,cpu,abi,allocations,splits,scaled");
         for( var row : ACTIVE._totals.entrySet() ) {
             long[] sum = row.getValue();
diff --git a/src/test/java/com/seaofnodes/simple/TestArm64.java b/src/test/java/com/seaofnodes/simple/TestArm64.java
index e4bc38a0..a22063eb 100644
--- a/src/test/java/com/seaofnodes/simple/TestArm64.java
+++ b/src/test/java/com/seaofnodes/simple/TestArm64.java
@@ -2,6 +2,8 @@ package com.seaofnodes.simple;
 
 import com.seaofnodes.isa.eval.EvalArm64;
 
+import com.seaofnodes.simple.codegen.RegAllocTestSupport.CheckedCodeGen;
+
 
 import com.seaofnodes.simple.codegen.CodeGen;
 import com.seaofnodes.simple.node.cpus.arm.arm;
@@ -23,9 +25,8 @@ public class TestArm64 {
     public static EvalArm64 build( String dir, String file, int arg, int spills, boolean print ) throws IOException {
         // Compile and export Simple
         String src = Files.readString(Path.of(dir+"/"+file+".smp"));
-        CodeGen code = new CodeGen(src).driver("arm", "SystemV",null);
-        com.seaofnodes.simple.codegen.RegAllocTestSupport.checkRegisters(code);
-        SpillStats.record(code,"Chapter21","arm","SystemV");
+        CodeGen code = new CheckedCodeGen(src).driver("arm", "SystemV",null);
+        SpillStats.recordNative(code,"arm","SystemV");
         if( print ) { code.print_as_hex(); System.out.print(code.asm()); }
 
         // Allocation quality not degraded
diff --git a/src/test/java/com/seaofnodes/simple/TestC.java b/src/test/java/com/seaofnodes/simple/TestC.java
index b3e21ea7..44c06128 100644
--- a/src/test/java/com/seaofnodes/simple/TestC.java
+++ b/src/test/java/com/seaofnodes/simple/TestC.java
@@ -1,10 +1,11 @@
 package com.seaofnodes.simple;
 
+import com.seaofnodes.simple.codegen.RegAllocTestSupport.CheckedCodeGen;
 import com.seaofnodes.simple.codegen.CodeGen;
+import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
-import java.io.InputStream;
-import java.io.IOException;
+import java.util.concurrent.TimeUnit;
 import static org.junit.Assert.*;
 
 // Call a C driver program, which calls a Simple-generated .o, and self-checks.
@@ -16,8 +17,8 @@ public abstract class TestC {
 
     public static final String CALL_CONVENTION = OS.startsWith("Windows") ? "Win64" : "SystemV";
     public static final String CPU_PORT = switch( CPU ) {
-    case "amd64" -> "x86_64_v2";
-    default -> throw Utils.TODO("Map Yer CPU Port Here");
+        case "amd64" -> "x86_64_v2";
+        default -> throw Utils.TODO("Map Yer CPU Port Here");
     };
 
     public static void run( String file, int spills ) throws IOException { run(file,"",spills); }
@@ -35,54 +36,69 @@ public abstract class TestC {
 
         // Compile and export Simple
         String src = Files.readString(Path.of(sfile));
-        _run(src,CALL_CONVENTION,"",cfile,efile,"S",expected,spills);
+        run(src,CALL_CONVENTION,"",cfile,efile,"S",expected,spills);
     }
 
-    static void _run( String src, String simple_conv, String c_conv, String cfile, String efile, String xtn, String expected, int spills ) throws IOException {
+    public static void run( String src, String simple_conv, String c_conv, String cfile, String efile, String xtn, String expected, int spills ) throws IOException {
         String bin = efile+xtn;
         String obj = bin+".o";
+        String exe = OS.startsWith("Windows") ? bin+".exe" : bin;
         // Compile simple, emit ELF
-        CodeGen code = new CodeGen(src).driver( CPU_PORT, simple_conv, obj);
-        com.seaofnodes.simple.codegen.RegAllocTestSupport.checkRegisters(code);
-        SpillStats.record(code,"Chapter21",CPU_PORT,simple_conv);
+        CodeGen code = new CheckedCodeGen(src).driver( CPU_PORT, simple_conv, obj);
+        SpillStats.recordNative(code,CPU_PORT,simple_conv);
+        String result = gcc(obj, c_conv, cfile, false, exe );
+        assertEquals(expected,result);
+
+        // Allocation quality not degraded
+        SpillStats.checkSpills(spills,code._regAlloc._spillScaled);
+    }
+
+    public static String gcc( String obj, String c_conv, String cfile, boolean stdin, String... args ) throws IOException {
+
+        // Compile the C program.  Compiling code and constants in the low
+        // 2Gig.  Pointers are 64b BUT since always in the low 2G all the
+        // high bits are zero - and Simple code can be emitted treating
+        // pointers as 4bytes.
+        var params = new Ary<>(String.class);
+        params.add("gcc");
+        if( cfile!=null ) params.add(cfile); // Associated C driver, usually has a `main`
+        params.addAll(new String[] {
+                obj,
+                "-lm", // Picks up 'sqrt' for newtonFloat tests to compare
+                "-g",
+                "-o",
+                args[0],
+        });
+        // Calling convention for C calls, if any
+        if( cfile!=null ) {
+            params.add("-D");
+            params.add("CALL_CONV="+c_conv);
+        }
 
-        // Compile the C program
-        var params = new String[] {
-            //if (USE_WSL) "wsl.exe";
-            "gcc",
-            cfile,
-            obj,
-            "-lm", // Picks up 'sqrt' for newtonFloat tests to compare
-            "-g",
-            "-o",
-            bin,
-            "-D",
-            "CALL_CONV="+c_conv,
-        };
-        Process gcc = new ProcessBuilder(params).redirectErrorStream(true).start();
-        int error;
-        try { error = gcc.waitFor(); } catch( InterruptedException e ) { throw new IOException("interrupted"); }
+        // Run GCC to link (optionally compile C driver code)
+        Process gcc = new ProcessBuilder(params.asAry()).redirectErrorStream(true).start();
+        int exit;
+        try {
+            boolean normal = gcc.waitFor(2, TimeUnit.SECONDS);
+            exit = normal ? gcc.exitValue() : -1; // no exit???
+        }  catch( InterruptedException e ) {
+            throw new IOException("interrupted");
+        }
         String result = new String(gcc.getInputStream().readAllBytes());
-        if( error!=0 ) {
-            System.err.println("gcc error code: "+error);
+        if( exit!=0 ) {
+            System.err.println("gcc error code: "+exit);
             System.err.println(result);
         }
-        assertEquals( 0, error );
+        assertEquals( 0, exit );
         //assertTrue(result.isEmpty()); // No data in error stream
 
         // Execute results
-        Process smp = new ProcessBuilder(bin).redirectErrorStream(true).start();
-        try { error = smp.waitFor(); } catch( InterruptedException e ) { throw new IOException("interrupted"); }
-        result = new String(smp.getInputStream().readAllBytes());
-        if( error!=0 ) {
-            System.err.println("exec error code: "+error);
-            System.err.println(result);
-        }
-        assertEquals( 0, error );
-        assertEquals(expected,result);
-
-        // Allocation quality not degraded
-        SpillStats.checkSpills(spills,code._regAlloc._spillScaled);
-
+        ProcessBuilder smp = new ProcessBuilder(args);
+        if( stdin ) smp.redirectInput(ProcessBuilder.Redirect.INHERIT);
+        Process p = smp.start();
+        try { exit = p.waitFor(); } catch( InterruptedException e ) { throw new IOException("interrupted"); }
+        result = new String(p.getInputStream().readAllBytes());
+        assertEquals("Program exit status",0,exit);
+        return result;
     }
 }
diff --git a/src/test/java/com/seaofnodes/simple/TestRisc5.java b/src/test/java/com/seaofnodes/simple/TestRisc5.java
index 1289575d..ace2a7ea 100644
--- a/src/test/java/com/seaofnodes/simple/TestRisc5.java
+++ b/src/test/java/com/seaofnodes/simple/TestRisc5.java
@@ -2,6 +2,7 @@ package com.seaofnodes.simple;
 
 import com.seaofnodes.isa.eval.EvalRisc5;
 
+import com.seaofnodes.simple.codegen.RegAllocTestSupport.CheckedCodeGen;
 import com.seaofnodes.simple.codegen.CodeGen;
 import com.seaofnodes.simple.node.FunNode;
 import com.seaofnodes.simple.node.Node;
@@ -22,9 +23,8 @@ public abstract class TestRisc5 {
     public static EvalRisc5 build( String dir, String file, String main, int arg, int spills, boolean print ) throws IOException {
         // Compile and export Simple
         String src = Files.readString(Path.of(dir+"/"+file+".smp"));
-        CodeGen code = new CodeGen(src).driver("riscv", "SystemV",null);
-        com.seaofnodes.simple.codegen.RegAllocTestSupport.checkRegisters(code);
-        SpillStats.record(code,"Chapter21","riscv","SystemV");
+        CodeGen code = new CheckedCodeGen(src).driver("riscv", "SystemV",null);
+        SpillStats.recordNative(code,"riscv","SystemV");
         if( print ) { code.print_as_hex(); System.out.print(code.asm()); }
 
         // Allocation quality not degraded
diff --git a/src/test/java/com/seaofnodes/simple/TypeTest.java b/src/test/java/com/seaofnodes/simple/TypeTest.java
index dee033bc..551bddad 100644
--- a/src/test/java/com/seaofnodes/simple/TypeTest.java
+++ b/src/test/java/com/seaofnodes/simple/TypeTest.java
@@ -20,9 +20,9 @@ public class TypeTest {
         TypeStruct s2 = TypeStruct.make("s2", new Field[]{
                 Field.make("a", TypeInteger.BOT,-3, false),
                 Field.make("b", TypeInteger.BOT,-4, false) });
-        Assert.assertEquals(s1.makeRO(), s1.glb());
+        Assert.assertEquals(s1.makeRO(), s1.glb(false));
         Assert.assertNotEquals(s1, s1.dual());
-        Assert.assertEquals(s1.makeRO(), s1.dual().glb());
+        Assert.assertEquals(s1.makeRO(), s1.dual().glb(false));
 
         TypeMem m1 = TypeMem.make(1,TypeNil.NIL);
         TypeMem m2 = TypeMem.make(2,TypeInteger.U16);
@@ -38,9 +38,9 @@ public class TypeTest {
         Assert.assertEquals(TypeMem.make(0,Type.BOTTOM), m1.meet(m3));
         Assert.assertEquals(TypeMem   .BOT, m3.meet(m4));
 
-        Assert.assertEquals(TypeMem.make(1,Type.BOTTOM), m1.glb());
+        Assert.assertEquals(TypeMem.make(1,Type.BOTTOM), m1.glb(false));
         Assert.assertEquals(TypeMem.make(1,Type.XNIL), m1.dual());
-        Assert.assertEquals(m4.dual(), m4.glb().dual());
+        Assert.assertEquals(m4.dual(), m4.glb(false).dual());
 
         TypeMemPtr ptr1 = TypeMemPtr.make(s1);
         Assert.assertEquals(s1, ptr1._obj);
@@ -55,11 +55,11 @@ public class TypeTest {
         Assert.assertEquals(s2, ptr2nil._obj);
 
         Assert.assertNotEquals(ptr1, ptr2);
-        Assert.assertNotEquals(ptr1, ptr1.glb());
-        Assert.assertEquals(ptr1nil.makeFrom(s1.glb()).makeRO(), ptr1.glb());
+        Assert.assertNotEquals(ptr1, ptr1.glb(false));
+        Assert.assertEquals(ptr1nil.makeFrom(s1.glb(false)).makeRO(), ptr1.glb(false));
 
         Assert.assertEquals(ptr1, ptr1.dual().dual());
-        Assert.assertEquals(ptr1.glb().makeFrom(s1.dual().glb()), ptr1.dual().glb());
+        Assert.assertEquals(ptr1.glb(false).makeFrom(s1.dual().glb(false)), ptr1.dual().glb(false));
         Assert.assertEquals(TypeMemPtr.makeNullable(TypeStruct.BOT).withAccess(false), ptr1.meet(ptr2nil));
         Assert.assertEquals(ptr1nil, ptr1.meet(TypeNil.NIL));
 
diff --git a/src/test/java/com/seaofnodes/simple/codegen/FlagSpillTestSupport.java b/src/test/java/com/seaofnodes/simple/codegen/FlagSpillTestSupport.java
index 7054ade4..00d86c63 100644
--- a/src/test/java/com/seaofnodes/simple/codegen/FlagSpillTestSupport.java
+++ b/src/test/java/com/seaofnodes/simple/codegen/FlagSpillTestSupport.java
@@ -60,7 +60,7 @@ public class FlagSpillTestSupport {
                 assertEquals(stack,slots!=0);
 
                 code._regAlloc=alloc;
-                FunNode frame = new FunNode(null,null,(Node)null);
+                FunNode frame = new FunNode(null,null,"flags",(Node)null);
                 Encoding save = new Encoding(code), restore = new Encoding(code);
                 save._fun=restore._fun=frame;
                 Encoding enc = save;
diff --git a/src/test/java/com/seaofnodes/simple/codegen/RegAllocTestSupport.java b/src/test/java/com/seaofnodes/simple/codegen/RegAllocTestSupport.java
index 06ed40d9..0895a4fc 100644
--- a/src/test/java/com/seaofnodes/simple/codegen/RegAllocTestSupport.java
+++ b/src/test/java/com/seaofnodes/simple/codegen/RegAllocTestSupport.java
@@ -123,6 +123,16 @@ public class RegAllocTestSupport {
         assertTrue(BuildLRG.run(0,new RegAlloc(code)));
     }
 
+    // Check the scheduled graph before encoding adds untyped branches or rewrites tail calls.
+    public static class CheckedCodeGen extends CodeGen {
+        public CheckedCodeGen(String src) { super(src); }
+        @Override public CodeGen regAlloc() {
+            super.regAlloc();
+            checkRegisters(this);
+            return this;
+        }
+    }
+
     public static void topPhi() {
         // Either arm can be the synthetic exit.  Both predecessors share a
         // block here so making TOP live would conflict with the real value.
diff --git a/src/test/java/com/seaofnodes/simple/codegen/X86EncodingTest.java b/src/test/java/com/seaofnodes/simple/codegen/X86EncodingTest.java
index 368c243b..0914d916 100644
--- a/src/test/java/com/seaofnodes/simple/codegen/X86EncodingTest.java
+++ b/src/test/java/com/seaofnodes/simple/codegen/X86EncodingTest.java
@@ -3,6 +3,7 @@ package com.seaofnodes.simple.codegen;
 import com.seaofnodes.simple.node.Node;
 import com.seaofnodes.simple.node.cpus.x86_64_v2.CmpMemX86;
 import com.seaofnodes.simple.node.cpus.x86_64_v2.NotX86;
+import com.seaofnodes.simple.node.cpus.x86_64_v2.MulIX86;
 import org.junit.Test;
 import static org.junit.Assert.*;
 
@@ -11,7 +12,7 @@ public class X86EncodingTest {
     @Test
     public void testLogicalNotRegisters() {
         CodeGen code = new CodeGen("return !arg;")
-            .driver(CodeGen.Phase.InstSelect, "x86_64_v2", "SystemV");
+            .driver(CodeGen.Phase.Select, "x86_64_v2", "SystemV");
         var not = code._stop.walk(n -> n instanceof NotX86 ? (NotX86)n : null);
         assertNotNull("Must exercise logical not", not);
         int[][] registers = {{0,0}, {1,1}, {7,7}, {9,9}, {1,9}, {9,1}, {6,0}, {15,8}};
@@ -50,6 +51,31 @@ public class X86EncodingTest {
             """);
         com.seaofnodes.simple.TestC.run("build/objs", "x86LogicalNot", "", -1);
     }
+
+    @Test
+    public void testMultiplyImmediateRegisters() {
+        // Destination, source, expected REX and ModRM. Cross the register-8
+        // boundary in both directions, with low/low and high/high controls.
+        int[][] cases = {{1, 9, 0x49, 0xC9}, {9, 1, 0x4C, 0xC9},
+                         {1, 2, 0x48, 0xCA}, {9, 10, 0x4D, 0xCA}};
+        for (int immediate : new int[]{11, -11, 123456789, -123456789}) {
+            CodeGen code = new CodeGen("return arg * " + immediate + ";")
+                .driver(CodeGen.Phase.Select, "x86_64_v2", "SystemV");
+            var mul = code._stop.walk(n -> n instanceof MulIX86 ? n : null);
+            assertNotNull("Must exercise immediate multiply", mul);
+            for (int[] regs : cases) {
+                var enc = new FixedRegisterEncoding(
+                    code, mul, regs[0], mul.in(1), regs[1]);
+                ((MulIX86)mul).encoding(enc);
+                boolean small = immediate == 11 || immediate == -11;
+                assertEquals("REX for dst=" + regs[0] + ", src=" + regs[1], regs[2], enc.read1(0));
+                assertEquals(small ? 0x6B : 0x69, enc.read1(1));
+                assertEquals(regs[3], enc.read1(2));
+                assertEquals(small ? 4 : 7, enc._bits.size());
+                assertEquals(immediate, small ? (byte)enc.read1(3) : enc.read4(3));
+            }
+        }
+    }
     @Test
     public void testMemoryCompare64Immediate32() {
         for (int immediate : new int[]{123456789, -123456789}) {
diff --git a/src/test/java/com/seaofnodes/simple/fuzzer/Fuzzer.java b/src/test/java/com/seaofnodes/simple/fuzzer/Fuzzer.java
index 7e8bdbf1..08e19fd4 100644
--- a/src/test/java/com/seaofnodes/simple/fuzzer/Fuzzer.java
+++ b/src/test/java/com/seaofnodes/simple/fuzzer/Fuzzer.java
@@ -133,7 +133,7 @@ public class Fuzzer {
             double parse_nop_ratio = (double)parse_nops/parse_peeps;
             double parse_peeps_per_node = (double)parse_peeps/nids;
 
-            code.iter();
+            code.iter().finalizeIR();
             int iter_peeps= code._iter_cnt;
             int iter_nops = code._iter_nop_cnt;
             double iter_nop_ratio = (double)iter_nops/iter_peeps;
diff --git a/src/test/java/com/seaofnodes/simple/fuzzer/ScriptGenerator.java b/src/test/java/com/seaofnodes/simple/fuzzer/ScriptGenerator.java
index 167a5b24..79547c0d 100644
--- a/src/test/java/com/seaofnodes/simple/fuzzer/ScriptGenerator.java
+++ b/src/test/java/com/seaofnodes/simple/fuzzer/ScriptGenerator.java
@@ -97,7 +97,7 @@ public class ScriptGenerator {
     private static final List<TypeInt> INTTYPES = new ArrayList<>();
 
     static {
-        for( var e : Parser.defaultTypes().entrySet() ) {
+        for( var e : Parser.TYPES.entrySet() ) {
             if( e.getValue() instanceof TypeInteger ) {
                 INTTYPES.add(new TypeInt(e.getKey()));
             }
diff --git a/src/test/java/com/seaofnodes/simple/progs/c_returns.c b/src/test/java/com/seaofnodes/simple/progs/c_returns.c
new file mode 100644
index 00000000..6d0ff2fe
--- /dev/null
+++ b/src/test/java/com/seaofnodes/simple/progs/c_returns.c
@@ -0,0 +1,28 @@
+#include <stdint.h>
+#include <stdio.h>
+
+uint64_t c_bits;
+// Legal narrow C returns: unused RAX bits deliberately contain garbage.
+#define RET(name) __asm__(".text\n.globl " #name "\n" #name ":\nmovq c_bits(%rip), %rax\nret\n");
+RET(c_i8) RET(c_u8) RET(c_i16) RET(c_u16) RET(c_i32) RET(c_u32) RET(c_i64)
+#define DECL(name) extern int64_t __attribute__((CALL_CONV)) name(void);
+DECL(test_i8) DECL(test_u8) DECL(test_i16) DECL(test_u16)
+DECL(test_i32) DECL(test_u32) DECL(test_i64) DECL(test_cmp)
+
+int main(void) {
+    uint64_t values[] = {0xa5a5a5a500000000ULL, 0xa5a5a5a50000007fULL,
+        0xa5a5a5a500000080ULL, 0xa5a5a5a500007fffULL, 0xa5a5a5a500008000ULL,
+        0xa5a5a5a57fffffffULL, 0xa5a5a5a580000000ULL, 0xa5a5a5a5ffffffffULL};
+    for(unsigned i=0; i<sizeof(values)/sizeof(values[0]); i++) {
+        c_bits=values[i];
+        int64_t actual[]={test_i8(),test_u8(),test_i16(),test_u16(),test_i32(),test_u32(),test_i64(),test_cmp()};
+        int64_t expected[]={(int8_t)c_bits,(uint8_t)c_bits,(int16_t)c_bits,(uint16_t)c_bits,
+                            (int32_t)c_bits,(uint32_t)c_bits,(int64_t)c_bits,(int32_t)c_bits==-1};
+        for(unsigned j=0; j<8; j++)
+            if(actual[j]!=expected[j]) {
+                printf("case %u type %u: %lld != %lld\n",i,j,(long long)actual[j],(long long)expected[j]);
+                return 1;
+            }
+    }
+    return 0;
+}
diff --git a/src/test/java/com/seaofnodes/simple/progs/echo.smp b/src/test/java/com/seaofnodes/simple/progs/echo.smp
new file mode 100644
index 00000000..8eafd73b
--- /dev/null
+++ b/src/test/java/com/seaofnodes/simple/progs/echo.smp
@@ -0,0 +1,3 @@
+// -*- mode: java;  -*-
+// Echo stdin to stdout.
+return sys.io.p( sys.io.stdin() );
diff --git a/src/test/java/com/seaofnodes/simple/progs/funptr.c b/src/test/java/com/seaofnodes/simple/progs/funptr.c
new file mode 100644
index 00000000..7545992d
--- /dev/null
+++ b/src/test/java/com/seaofnodes/simple/progs/funptr.c
@@ -0,0 +1,15 @@
+#include <assert.h>
+#include <stdint.h>
+
+typedef int64_t (*Function)(void);
+typedef int64_t (*Printer)(void *);
+extern Function factory(int64_t);
+extern Printer printer(void);
+
+int main(void) {
+    assert(factory(1)() == 42);
+    assert(factory(0)() == 43);
+    struct { uint32_t length; char data[2]; } text = {2, {'o','k'}};
+    printer()(&text);
+    return 0;
+}
diff --git a/src/test/java/com/seaofnodes/simple/progs/helloWorld.smp b/src/test/java/com/seaofnodes/simple/progs/helloWorld.smp
new file mode 100644
index 00000000..07ff935f
--- /dev/null
+++ b/src/test/java/com/seaofnodes/simple/progs/helloWorld.smp
@@ -0,0 +1,3 @@
+// -*- mode: java;  -*-
+sys.io.p("Hello, World!");
+return 0;
diff --git a/src/test/java/com/seaofnodes/simple/progs/jig.smp b/src/test/java/com/seaofnodes/simple/progs/jig.smp
index 1daeee09..29987d8e 100644
--- a/src/test/java/com/seaofnodes/simple/progs/jig.smp
+++ b/src/test/java/com/seaofnodes/simple/progs/jig.smp
@@ -1,2 +1,16 @@
 // -*- mode: java;  -*-
-return 0;
+val _fib = {int n ->
+    int temp=0;
+    int f1=1;
+    int f2=1;
+    int i=n;
+    while( i>1 ){
+        temp = f1+f2;
+        f1=f2;
+        f2=temp;
+        i=i-1;
+    }
+    return f2;
+};
+
+_fib(10);
diff --git a/src/test/java/com/seaofnodes/simple/progs/person.smp b/src/test/java/com/seaofnodes/simple/progs/person.smp
index b5e6ee90..94e2cdde 100644
--- a/src/test/java/com/seaofnodes/simple/progs/person.smp
+++ b/src/test/java/com/seaofnodes/simple/progs/person.smp
@@ -1,6 +1,6 @@
 // -*-java-*-
 struct Person {
-    int age;
+    i32 age;
 };
 
 val fcn = { !Person?[] ps, int x ->
diff --git a/src/test/java/com/seaofnodes/simple/progs/person21.c b/src/test/java/com/seaofnodes/simple/progs/person21.c
new file mode 100644
index 00000000..df95e1ca
--- /dev/null
+++ b/src/test/java/com/seaofnodes/simple/progs/person21.c
@@ -0,0 +1,34 @@
+#include <stdio.h>
+#include <stdbool.h>
+#include <stdlib.h>
+
+typedef struct Person {
+    int age;
+} Person;
+
+typedef struct PersonArray {
+    unsigned int length;
+    int pad;
+    Person* data[];
+} PersonArray;
+
+__attribute__ ((CALL_CONV))
+extern void fcn(PersonArray* people, int index);
+
+int main() {
+    Person base[5] = {{25},{1},{18},{45},{60}};
+    unsigned char buf[8+8*5];
+    PersonArray* people_array = (PersonArray*)buf;
+    people_array->length=5;
+    for (int i=0; i<people_array->length; i++) people_array->data[i] = &base[i];
+
+    fcn(people_array, 1);
+    fcn(people_array, 1);
+    fcn(people_array, 1);
+    fcn(people_array, 1);
+    fcn(people_array, 1);
+
+    printf("%d\n", people_array->data[1]->age); // expected: 6
+
+    return 0;
+}
\ No newline at end of file
diff --git a/src/test/java/com/seaofnodes/simple/progs/person21.smp b/src/test/java/com/seaofnodes/simple/progs/person21.smp
new file mode 100644
index 00000000..b5e6ee90
--- /dev/null
+++ b/src/test/java/com/seaofnodes/simple/progs/person21.smp
@@ -0,0 +1,9 @@
+// -*-java-*-
+struct Person {
+    int age;
+};
+
+val fcn = { !Person?[] ps, int x ->
+    if( ps[x] )
+        ps[x].age++;
+};
\ No newline at end of file
diff --git a/src/test/java/com/seaofnodes/simple/progs/riscv_load.smp b/src/test/java/com/seaofnodes/simple/progs/riscv_load.smp
new file mode 100644
index 00000000..1a36fb99
--- /dev/null
+++ b/src/test/java/com/seaofnodes/simple/progs/riscv_load.smp
@@ -0,0 +1,4 @@
+struct Person { i32 age;};
+!Person !p = new Person;
+p.age += arg;
+return p.age;
diff --git a/src/test/java/com/seaofnodes/simple/progs/sext_str_1.smp b/src/test/java/com/seaofnodes/simple/progs/sext_str_1.smp
new file mode 100644
index 00000000..57b37477
--- /dev/null
+++ b/src/test/java/com/seaofnodes/simple/progs/sext_str_1.smp
@@ -0,0 +1,4 @@
+struct Person {i64 age;}
+!Person !p  = new Person;
+p.age += arg;
+return p.age;
diff --git a/src/test/java/com/seaofnodes/simple/progs/sext_str_fold_away.smp b/src/test/java/com/seaofnodes/simple/progs/sext_str_fold_away.smp
new file mode 100644
index 00000000..7d7fdce7
--- /dev/null
+++ b/src/test/java/com/seaofnodes/simple/progs/sext_str_fold_away.smp
@@ -0,0 +1,5 @@
+// Should fold away sign extend
+struct Person { i8 age;};
+!Person !p = new Person;
+p.age = (arg<<48)>>48;
+return 0;
\ No newline at end of file
diff --git a/src/test/java/com/seaofnodes/simple/progs/sext_str_not_fold_away.smp b/src/test/java/com/seaofnodes/simple/progs/sext_str_not_fold_away.smp
new file mode 100644
index 00000000..4d6ca3a3
--- /dev/null
+++ b/src/test/java/com/seaofnodes/simple/progs/sext_str_not_fold_away.smp
@@ -0,0 +1,4 @@
+struct Person { i32 age;};
+!Person !p = new Person;
+p.age = (arg<<17)>>17;
+return 0;
\ No newline at end of file
diff --git a/src/test/java/com/seaofnodes/simple/progs/sext_str_not_fold_away_2.smp b/src/test/java/com/seaofnodes/simple/progs/sext_str_not_fold_away_2.smp
new file mode 100644
index 00000000..5c96c060
--- /dev/null
+++ b/src/test/java/com/seaofnodes/simple/progs/sext_str_not_fold_away_2.smp
@@ -0,0 +1,4 @@
+struct Person { i32 age;};
+!Person !p = new Person;
+p.age = (arg<<48)>>48;
+return 0;
\ No newline at end of file
diff --git a/src/test/java/com/seaofnodes/simple/progs/store_peep.smp b/src/test/java/com/seaofnodes/simple/progs/store_peep.smp
new file mode 100644
index 00000000..c3feddd5
--- /dev/null
+++ b/src/test/java/com/seaofnodes/simple/progs/store_peep.smp
@@ -0,0 +1,3 @@
+i64 a = 123456789012345;
+i32 b = a; // truncate high order bits
+return b;
\ No newline at end of file