Cleanup & backportclinit

The phase rework, made new phases explicit and add them to the CodeGen driver.  Fix the flag-spilling on X86 and ARM.  Fix the GCM conservative anti-deps and backport.

34 files changed, 671 insertions, 289 deletions

diff --git a/chapter25/src/test/java/com/seaofnodes/simple/BulkMemPhiTest.java b/chapter25/src/test/java/com/seaofnodes/simple/BulkMemPhiTest.java
new file mode 100644
index 00000000..31c0302b
--- /dev/null
+++ b/chapter25/src/test/java/com/seaofnodes/simple/BulkMemPhiTest.java
@@ -0,0 +1,40 @@
+package com.seaofnodes.simple;
+
+import com.seaofnodes.simple.codegen.CodeGen;
+import com.seaofnodes.simple.node.*;
+import com.seaofnodes.simple.type.TypeInteger;
+import com.seaofnodes.simple.type.TypeMem;
+import org.junit.Test;
+import static org.junit.Assert.*;
+
+public class BulkMemPhiTest {
+    // Reduced from Capitalize's Lower-phase failure. A precise MemMerge slot
+    // may still be supplied by bulk memory which covers the requested alias.
+    @Test public void testBulkInPreciseSlot() {
+        CodeGen code=new CodeGen("");
+        code._phase=CodeGen.Phase.Lower;
+        Node m0=code.con(TypeMem.START), m1=code.con(TypeMem.BOT);
+        Node ctrl=new CProjNode(code._start,0,"Ctrl").init();
+        Node iff=new IfNode(ctrl,code.con(TypeInteger.BOOL)).init();
+        RegionNode region=new RegionNode(null,null,
+            new CProjNode(iff,0,"True").init(),
+            new CProjNode(iff,1,"False").init()).init();
+        BulkMemPhiNode bulk=new BulkMemPhiNode("$mem",region,m0,m1).init();
+        // A later init check proves its call arm dead. Its precise Phi can
+        // collapse before the surrounding aggregate gets another peephole.
+        RegionNode done=new RegionNode(null,null,region,code.XCTRL).init();
+        MemPhiNode precise=new MemPhiNode("$4",4,done,bulk,m1).init();
+        MemMergeNode merge=new MemMergeNode(null,m0);
+        merge.alias(4,precise);
+        merge.init();
+        Node folded=precise.peepholeOpt();
+        assertSame(bulk,folded);
+        precise.subsume(folded);
+
+        assertFalse(bulk.isSplit(4));
+        assertSame(bulk,merge.alias(4));
+        // Splitting this still-covered alias must tolerate the direct bulk use.
+        Node mem = bulk.idealize();
+        bulk.subsume(mem);
+    }
+}
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/Chapter05Test.java b/chapter25/src/test/java/com/seaofnodes/simple/Chapter05Test.java
index 5b57e701..afdb1071 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/Chapter05Test.java
+++ b/chapter25/src/test/java/com/seaofnodes/simple/Chapter05Test.java
@@ -20,7 +20,7 @@ else {
 }
 return a;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return Phi(Region,(arg+2),(arg-3));", code.print());
     }
 
@@ -36,7 +36,7 @@ if (arg == 1) {
 }
 return c;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         String ir = code.print();
         assertTrue(ir,
                    ir.equals("return ((arg+Phi(Region,1,0))+Phi(Region,2,0));") ||
@@ -133,7 +133,7 @@ if( arg==1 )
 }
 return a;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return (arg==Phi(Region,3,2));", code.print());
     }
 
@@ -148,7 +148,7 @@ else
     a=3;
 return a;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 3;", code.print());
     }
 
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/Chapter06Test.java b/chapter25/src/test/java/com/seaofnodes/simple/Chapter06Test.java
index c503b56c..d1af5d14 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/Chapter06Test.java
+++ b/chapter25/src/test/java/com/seaofnodes/simple/Chapter06Test.java
@@ -15,7 +15,7 @@ public class Chapter06Test {
 if( true ) return 2;
 return 1;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 1;", code.print());
     }
 
@@ -44,7 +44,7 @@ else
   a=3;
 return a;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 2;", code.print());
         assertTrue(code.ctrl() instanceof FunNode);
     }
@@ -65,7 +65,7 @@ else
     b=5;
 return b;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return Phi(Region,42,5);", code.print());
     }
 
@@ -84,7 +84,7 @@ if( arg==2 )
 else
     b=5;
 return b;""");
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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)).parse().iter().opto().iterPostOpto().finalizeIR();
+""", TypeInteger.constant(2)).driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 5;", code.print());
     }
 
@@ -124,7 +124,7 @@ else if( arg==3 )
 else
     a=5;
 return a;
-""", TypeInteger.constant(1)).parse().iter().opto().iterPostOpto().finalizeIR();
+""", TypeInteger.constant(1)).driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 3;", code.print());
     }
 
@@ -144,7 +144,7 @@ else
     a=5;
 return a;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return Phi(Region,3,5,4);", code.print());
     }
 
@@ -165,7 +165,7 @@ else
     a=5;
 return a;
 """, TypeInteger.constant(1));
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 3;", code.print());
     }
 
@@ -186,7 +186,7 @@ else
     a=5;
 return a;
 """, TypeInteger.constant(3));
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 4;", code.print());
     }
 
@@ -202,7 +202,7 @@ if( arg ) {
 }
 return a+b;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return Phi(Region,4,1);", code.print());
     }
 
@@ -221,7 +221,7 @@ if( arg ) {
 }
 return a+b;
 """, TypeInteger.constant(1));
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 4;", code.print());
     }
 
@@ -239,7 +239,7 @@ if( arg ) {
 }
 return a+b;
 """, TypeInteger.constant(0));
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 1;", code.print());
     }
 
@@ -257,7 +257,7 @@ if( arg ) {
 }
 return a+b+c;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return Phi(Region,6,1,5);", code.print());
     }
 
@@ -278,7 +278,7 @@ if( arg ) {
 }
 return a+b+c;
 """, TypeInteger.constant(1));
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 6;", code.print());
     }
 
@@ -298,7 +298,7 @@ if( arg ) {
 }
 return a+b+c;
 """, TypeInteger.constant(2));
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 5;", code.print());
     }
 
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/Chapter07Test.java b/chapter25/src/test/java/com/seaofnodes/simple/Chapter07Test.java
index 498038c1..7094c0d5 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/Chapter07Test.java
+++ b/chapter25/src/test/java/com/seaofnodes/simple/Chapter07Test.java
@@ -17,7 +17,7 @@ while(arg < 10) {
 }
 return arg;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return Phi(Loop,arg,(Phi_arg+1));", code.print());
         assertTrue(code.ctrl() instanceof CProjNode);
     }
@@ -34,7 +34,7 @@ if(arg){}else{
 }
 return a;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return Phi(Loop,2,(Phi(Region,Phi_b,4)+1));", code.print());
         assertTrue(code.ctrl() instanceof CProjNode);
     }
@@ -106,7 +106,7 @@ while(a < 10) {
 }
 return a;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return Phi(Loop,1,(Phi_a+3));", code.print());
         assertTrue(code.ctrl() instanceof CProjNode);
     }
@@ -122,7 +122,7 @@ while(a < 10) {
 }
 return a;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return Phi(Loop,1,2);", code.print());
         assertTrue(code.ctrl() instanceof CProjNode);
     }
@@ -164,7 +164,7 @@ while(a < 10) {
 }
 return a;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return Phi(Loop,1,(Phi_a+3));", code.print());
         assertTrue(code.ctrl() instanceof CProjNode);
     }
@@ -180,7 +180,7 @@ while(a < 10) {
 }
 return a;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return Phi(Loop,1,(Phi_a+3));", code.print());
         assertTrue(code.ctrl() instanceof CProjNode);
     }
@@ -197,7 +197,7 @@ while(a < 10) {
 }
 return a;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return Phi(Loop,1,(Phi_a+3));", code.print());
         assertTrue(code.ctrl() instanceof CProjNode);
     }
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/Chapter08Test.java b/chapter25/src/test/java/com/seaofnodes/simple/Chapter08Test.java
index 61815840..376e472b 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/Chapter08Test.java
+++ b/chapter25/src/test/java/com/seaofnodes/simple/Chapter08Test.java
@@ -22,7 +22,7 @@ while(arg < 10) {
 }
 return arg;
                 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 0;", code.print());
     }
 
@@ -167,7 +167,7 @@ while(arg < 10) {
 }
 return arg;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return arg;", code.print());
     }
 
@@ -184,7 +184,7 @@ while(arg < 10) {
 }
 return a;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return (Phi(Loop,1,Add)+1);", code.print());
         assertTrue(code.ctrl() instanceof CProjNode prj && prj._idx==1 );
     }
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/Chapter09Test.java b/chapter25/src/test/java/com/seaofnodes/simple/Chapter09Test.java
index 839b834d..7025b98a 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/Chapter09Test.java
+++ b/chapter25/src/test/java/com/seaofnodes/simple/Chapter09Test.java
@@ -24,7 +24,7 @@ while(v0) {
 }
 return 0;
                 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
     }
 
     @Test
@@ -40,7 +40,7 @@ else {
 }
 return x;
                 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 0;", code.print());
     }
 
@@ -128,14 +128,14 @@ while(v1+arg) {
 }
 return 0;
                 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 0;", code.print());
     }
 
     @Test
     public void testWhile0() {
         CodeGen code = new CodeGen("while(0) continue; if(0) arg=0; return arg;");
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return arg;", code.print());
     }
 
@@ -148,7 +148,7 @@ if(0) while(0) {
 }
 return 0;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 0;", code.print());
     }
 
@@ -156,14 +156,14 @@ return 0;
     @Test
     public void testPrecedence() {
         CodeGen code = new CodeGen("return 3-1+2;");
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 4;", code.print());
     }
 
     @Test
     public void testSwap2() {
         CodeGen code = new CodeGen("return 1+(1+1);");
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 3;", code.print());
     }
 
@@ -181,7 +181,7 @@ while(arg) {
 }
 return a;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return Phi(Loop,0,(-(Phi_a+3)));", code.print());
     }
 
@@ -195,7 +195,7 @@ arg=0;
 int v0=0!=0<-0;
 return -0+0+0;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return Top;", code.print());
     }
 
@@ -203,14 +203,14 @@ return -0+0+0;
     @Test
     public void testFuzz2() {
         CodeGen code = new CodeGen("return 0+-0;");
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 0;", code.print());
     }
 
     @Test
     public void testFuzz3() {
         CodeGen code = new CodeGen("int v0=0; while(0==69) while(v0) return 0; return 1;");
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 1;", code.print());
     }
 
@@ -222,7 +222,7 @@ while(1) {
     if(1<0) while(arg==-0) arg=arg-arg;
 }
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return Top;", code.print());
     }
 
@@ -244,7 +244,7 @@ while(1) {
 }
 return 0!=0;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return Top;", code.print());
     }
 
@@ -257,7 +257,7 @@ while(0==1) while(v0)
         v0=1+v0;
 return 0;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 0;", code.print());
     }
 
@@ -273,14 +273,14 @@ while(1)
         v1=1;
 return v1+v0;
                                    """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return Top;", code.print());
     }
 
     @Test
     public void testFuzz8() {
         CodeGen code = new CodeGen("while(arg) arg = arg - 1;  return arg;");
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 0;", code.print());
     }
 
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/Chapter10Test.java b/chapter25/src/test/java/com/seaofnodes/simple/Chapter10Test.java
index 1b542d63..924884ac 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/Chapter10Test.java
+++ b/chapter25/src/test/java/com/seaofnodes/simple/Chapter10Test.java
@@ -12,7 +12,7 @@ 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().opto().iterPostOpto().finalizeIR().typeCheck();
+            var code = new CodeGen(src).driver(CodeGen.Phase.TypeCheck);
             // This chapter also has constructor/class-init Returns in the CompUnit.
             var entry = (com.seaofnodes.simple.node.FunNode)code._start.uctrl();
             org.junit.Assert.assertTrue(body,
@@ -102,7 +102,7 @@ if( (arg/13)==0 ) {
 int r = g+h;
 return p-r;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 0;", code.print());
     }
 
@@ -122,7 +122,7 @@ bar.a = 1;
 bar.a = 2;
 return bar.a;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 2;", code.print());
     }
 
@@ -138,7 +138,7 @@ else
     v.y = 3;
 return v;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("Stop[ return Test.Vector2D; return MEM[ 2:___ 3:.x=0; 4:.y=0;]; return Test.Vector2D; ]", code.print());
     }
 
@@ -151,7 +151,7 @@ struct s0 {
 s0? v1=null;
 int v3=v1.zAicm;
 """);
-        try { code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck();  fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck);  fail(); }
         catch( Exception e ) {  assertEquals("Might be null accessing 'zAicm'",e.getMessage());  }
     }
 
@@ -176,7 +176,7 @@ while (arg) {
 }
 return bar.a;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("Stop[ return Phi(Loop,0,(Phi_a+2)); return MEM[ 2:___ 3:.a=0;]; return Test.Bar; ]", code.print());
     }
 
@@ -189,7 +189,7 @@ if (arg) bar = null;
 bar.a = 1;
 return bar.a;
 """);
-        try { code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck(); fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
         catch( Exception e ) { assertEquals("Type null is not of declared type *Test.Bar",e.getMessage()); }
     }
 
@@ -202,7 +202,7 @@ if (arg) bar = new Bar;
 bar.a = 1;
 return bar.a;
 """);
-        try { code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck(); fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
         catch( Exception e ) { assertEquals("Might be null accessing 'a'",e.getMessage()); }
     }
 
@@ -215,7 +215,7 @@ if (arg) bar = null;
 bar.a = 1;
 return bar.a;
 """);
-        try { code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck(); fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
         catch( Exception e ) { assertEquals("Type null is not of declared type *Test.Bar", e.getMessage()); }
     }
 
@@ -228,7 +228,7 @@ if (arg) bar = null;
 if( bar ) bar.a = 1;
 return bar.a;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return Phi(Region,1,.a);", code.print());
     }
 
@@ -244,7 +244,7 @@ if( !bar ) rez=4;
 else bar.a = 1;
 return rez;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return Phi(Region,4,3);", code.print());
     }
 
@@ -261,7 +261,7 @@ while(arg) {
 }
 return ret;
 """);
-        try { code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck(); fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
         catch( Exception e ) {
             assertEquals("Might be null accessing 'v0'", e.getMessage()); }
     }
@@ -298,7 +298,7 @@ while( i.x < i.len ) {
 }
 return sum;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("Stop[ return Phi(Loop,0,(Phi(Loop,0,(Phi_x+1))+Phi_sum)); return MEM[ 2:___ 3:.x=0; 4:.len=0;]; return Test.Iter; ]", code.print());
     }
 
@@ -317,7 +317,7 @@ while(arg) {
 }
 return ret;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("Stop[ return Phi(Loop,Test.s0,Phi(Region,Test.s0,Phi_ret)); return MEM[ 2:___ 3:.v0=0;]; return Test.s0; ]", code.print());
     }
 
@@ -334,7 +334,7 @@ while(arg) {
 }
 return ret.v0;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return .v0;", code.print());
     }
 
@@ -351,7 +351,7 @@ while(arg < 10) {
 }
 return ret.v0;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return .v0;", code.print());
     }
 
@@ -370,7 +370,7 @@ s0 b = new s0();
 // a.x==1, b.x==1, cnt==2
 return a.x * 100 + b.x * 10 + cnt;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("Stop[ return 112; return MEM[ 2:___ 3:___ 4:.x=1;]; return Test.s0; ]", code.print());
     }
 
@@ -399,7 +399,7 @@ if(0) {
 }
 return 0;
    """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 0;", code.print());
     }
 
@@ -413,7 +413,7 @@ if(0) return 0;
 else return new s0;
 if(new s0.f0) return 0;
     """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck();
+        code.driver(CodeGen.Phase.TypeCheck);
         assertEquals("Stop[ return Test.s0; return MEM[ 2:___ 3:.f0=0;]; return Test.s0; ]", code.print());
     }
 
@@ -429,7 +429,7 @@ while(0<arg) {
 }
 return 0;
     """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
     }
 
     @Test
@@ -441,7 +441,7 @@ while(v0.f0) {}
 s0 v1 = v0;
 return v1;
     """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("Stop[ return (const)Test.s0; return MEM[ 2:___ 3:.f0=0;]; return Test.s0; ]", code.print());
     }
 
@@ -474,7 +474,7 @@ while(0) {}
 }
 return 0;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 0;", code.print());
     }
 
@@ -485,7 +485,7 @@ int v0=arg==0;
 while(v0) continue;
 return 0;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 0;", code.print());
     }
 
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/Chapter12Test.java b/chapter25/src/test/java/com/seaofnodes/simple/Chapter12Test.java
index 19c531f8..fae7611d 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/Chapter12Test.java
+++ b/chapter25/src/test/java/com/seaofnodes/simple/Chapter12Test.java
@@ -14,7 +14,7 @@ public class Chapter12Test {
 """
 return 3;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 3;", code.print());
         assertEquals("3", Eval2.eval(code,  0));
     }
@@ -34,7 +34,7 @@ while( arg ) {
 }
 return head.next.i;
 """);
-        try { code.parse().iter().opto().iterPostOpto().finalizeIR().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.q;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck();
+        code.driver(CodeGen.Phase.TypeCheck);
         assertEquals("return Phi(Region,1,.q,0);", 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().opto().iterPostOpto().finalizeIR().typeCheck();
+        code.driver(CodeGen.Phase.TypeCheck);
         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().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return null;", code.print());
     }
 
@@ -100,7 +100,7 @@ struct N { !M !next; int i; new N = { !M m -> next = m; }; };
 N n = new N(new M);
 return n.next;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("Stop[ return (const)Test.M; return MEM[ 2:___ 3:.m=0;]; return Test.M; return MEM[ 2:___ 3:___ 4:___ 5:___ 6:___ 7:.next=Parm_m(Test.N.N,*Test.M {i64 !m; }); 8:.i=0;]; return MEM[ 2:___ 3:___ 4:___ 5:___ 6:___ 7:___ 8:.i=0;]; return Test.N; ]", code.print());
     }
 
@@ -113,7 +113,7 @@ struct N { !M !next; int i; new N = { !M m -> next = m; }; };
 N n = new N(null);
 return n.next;
 """);
-        try { code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck(); fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
         catch( Exception e ) { assertEquals("Argument #0 isa null, but must be a *Test.M {i64 !m; }",e.getMessage()); }
     }
 
@@ -126,20 +126,20 @@ struct N { !N? !next; int i; };
 n.i = 3.14;
 return n.i;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck();
+        code.driver(CodeGen.Phase.TypeCheck);
         assertEquals("3",Eval2.eval(code,0));
     }
 
     @Test
     public void testNullRef4() {
         CodeGen code = new CodeGen("return -null-5/null-5;");
-        try { code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck(); fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
         catch( Exception e ) { assertEquals("Cannot null + 5",e.getMessage()); }
     }
 
     @Test public void testNullRef5() {
         CodeGen code = new CodeGen("return null+42;");
-        try { code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck(); fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
         catch( Exception e ) { assertEquals("Cannot null + 42",e.getMessage()); }
     }
 
@@ -150,7 +150,7 @@ return n.i;
 struct _S{};
 return 0;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 0;", code.print());
         assertEquals("0", Eval2.eval(code,  0));
     }
@@ -162,7 +162,7 @@ return 0;
 struct S1 { S2? s; };
 return new S2;
 """);
-        try { code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck(); fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
         catch( Exception e ) { assertEquals("Unknown struct type 'S2'",e.getMessage()); }
     }
 
@@ -174,7 +174,7 @@ struct _S1 { !_S2? !s; };
 struct _S2 { int x; };
 return (new _S1).s=new _S2;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return Test._S2;", code.print());
     }
 
@@ -191,7 +191,7 @@ p2.pi.i = 2;
 if (arg) p1 = new P;
 return p1.pi.i + 1;
 """);
-        try { code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck();  fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck);  fail(); }
         catch( Exception e ) {  assertEquals("Might be null accessing 'i'",e.getMessage());  }
     }
 
@@ -210,7 +210,7 @@ c.f0=a;  c.f1=b;
 return a.f0.f1.f0.f1.f0;
 
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck().GCM().localSched();
+        code.driver(CodeGen.Phase.FinalizeIR).driver(CodeGen.Phase.Schedule).localSched();
         assertEquals("return Test._B;", code.print());
         assertEquals("Test._B{f0=Test._C{f0=Test._A{f0=$cyclic,f1=$cyclic},f1=$cyclic},f1=$cyclic}", Eval2.eval(code,  0));
     }
@@ -276,7 +276,7 @@ z.a=k;  z.b=s; z.c=e;
 return a.b.c.a.b.c.a.b.c.a.b.c.a.b.c.a.b.c;
 
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck().GCM().localSched();
+        code.driver(CodeGen.Phase.FinalizeIR).driver(CodeGen.Phase.Schedule).localSched();
         assertEquals("return Test._R;", code.print());
         assertEquals("Test._R{a=Test._C{a=Test._N{a=Test._Y{a=Test._J{a=Test._U{a=Test._F{a=Test._Q{a=Test._B{a=Test._M{a=Test._X{a=Test._I{a=Test._T{a=Test._E{a=Test._P{a=Test._A{a=Test._L{a=Test._W{a=Test._H{a=Test._S{a=Test._D{a=Test._O{a=Test._Z{a=Test._K{a=Test._V{a=Test._G{a=$cyclic,b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic},b=$cyclic,c=$cyclic}", Eval2.eval(code,  0));
     }
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/Chapter13Test.java b/chapter25/src/test/java/com/seaofnodes/simple/Chapter13Test.java
index 9786006c..214bc69e 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/Chapter13Test.java
+++ b/chapter25/src/test/java/com/seaofnodes/simple/Chapter13Test.java
@@ -34,7 +34,7 @@ while( prime <= arg ) {
 }
 return primeCount;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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
@@ -73,7 +73,7 @@ i=v.f;
 if (arg) v.f=1;
 return i;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 2;", code.print());
         assertEquals("2", Eval2.eval(code, 0));
         assertEquals("2", Eval2.eval(code, 1));
@@ -96,7 +96,7 @@ if (arg) {
 }
 return i;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return Phi(Region,.f,0);", code.print());
     }
 
@@ -115,7 +115,7 @@ if (v1) {
 }
 return v0.f;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return Phi(Region,.f,2);", code.print());
     }
 
@@ -133,7 +133,7 @@ if (arg+1) arg= 0;
 while (arg) v.f = 2;
 return i;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return arg;", code.print());
     }
 
@@ -150,7 +150,7 @@ while(1) {
 }
 return v.f;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return Phi(Loop,0,2);", code.print());
         for( int arg : new int[]{-1,0,1,3,100} )
             assertEquals("0",Eval2.eval(code,arg));
@@ -167,7 +167,7 @@ while( -arg )
 while(1)
   arg = arg+ptr.v;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return Top;", code.print());
     }
 
@@ -185,7 +185,7 @@ while (arg) {
 }
 return i;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 0;", code.print());
     }
 
@@ -205,7 +205,7 @@ while(arg) {
 }
 return arg;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 0;", code.print());
     }
 
@@ -223,7 +223,7 @@ if (arg) {
 }
 return v.f;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 0;", code.print());
     }
 
@@ -242,7 +242,7 @@ while (arg > 0) {
 }
 return v;
                 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         //assertEquals("return new _S;", code.print());
     }
 
@@ -259,7 +259,7 @@ while(0>=0) {
 }
 return 0;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return Top;", code.print());
     }
 
@@ -277,7 +277,7 @@ u32 v0=0;
     return v1;
 }
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 0;", code.print());
     }
 
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/Chapter14FloatTest.java b/chapter25/src/test/java/com/seaofnodes/simple/Chapter14FloatTest.java
index ccca2e2b..e058a822 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/Chapter14FloatTest.java
+++ b/chapter25/src/test/java/com/seaofnodes/simple/Chapter14FloatTest.java
@@ -18,7 +18,7 @@ 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().opto().iterPostOpto().finalizeIR().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));
         }
@@ -26,7 +26,7 @@ public class Chapter14FloatTest {
 
 
     @Test public void testSubZeroFloat() {
-        var code = new CodeGen("flt x = arg; return 0-x;").parse().iter().opto().iterPostOpto().finalizeIR().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));
@@ -40,7 +40,7 @@ public class Chapter14FloatTest {
             {"return 2.5; return 7;", "2.5"}
         } ) {
             String src = test[0];
-            var code = new CodeGen(src).parse().iter().opto().iterPostOpto().finalizeIR().typeCheck();
+            var code = new CodeGen(src).driver(CodeGen.Phase.TypeCheck);
             assertEquals(src,test[1],Eval2.eval(code,0));
         }
     }
@@ -53,7 +53,7 @@ public class Chapter14FloatTest {
 """
 return 0;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 0;", code.print());
         assertEquals("0", Eval2.eval(code,  0));
     }
@@ -65,7 +65,7 @@ return 0;
 flt x = 3.14;
 return 0;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 0;", code.print());
         assertEquals("0", Eval2.eval(code,  0));
     }
@@ -84,7 +84,7 @@ return guess;
 """);
         // TODO: One of the problems with <clinit> returning an OS error code,
         // is it chops all results to int.
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return Phi(Loop,(flt)arg,((Phi_guess+(ToFloat/Phi_guess))*0.5f));", code.print());
         assertEquals("3.0", Eval2.eval(code,  9));
         assertEquals("1.414213562373095", Eval2.eval(code,  2));
@@ -97,7 +97,7 @@ return guess;
 flt x = arg;
 return x+1==x;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return ((flt)arg==(ToFloat+1.0f));", code.print());
         assertEquals("0", Eval2.eval(code, 1));
     }
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/Chapter14Test.java b/chapter25/src/test/java/com/seaofnodes/simple/Chapter14Test.java
index 3ba03b48..bc2ad8d3 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/Chapter14Test.java
+++ b/chapter25/src/test/java/com/seaofnodes/simple/Chapter14Test.java
@@ -16,7 +16,7 @@ public class Chapter14Test {
 """
 return 3.14;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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().opto().iterPostOpto().finalizeIR().typeCheck();
+        code.driver(CodeGen.Phase.TypeCheck);
         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().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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().opto().iterPostOpto().finalizeIR().typeCheck(); fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
         catch( Exception e ) { assertEquals("Cannot '&' flt",e.getMessage()); }
     }
 
@@ -175,7 +175,7 @@ while(arg) v1=-v0;
 while(v1) break;
 return v1;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 0;", code.print());
         assertEquals("0", Eval2.eval(code,  0));
     }
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/Chapter15Test.java b/chapter25/src/test/java/com/seaofnodes/simple/Chapter15Test.java
index 3c1254d2..25f00474 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/Chapter15Test.java
+++ b/chapter25/src/test/java/com/seaofnodes/simple/Chapter15Test.java
@@ -17,7 +17,7 @@ public class Chapter15Test {
 """
 return 3.14;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 3.14;", code.print());
         assertEquals("3.14", Eval2.eval(code,  0));
     }
@@ -31,7 +31,7 @@ struct _C { !_C? !l; };
 c.l = c;
 return c;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return Test._C;", code.print());
         assertEquals("Test._C{l=$cyclic}", Eval2.eval(code,  0));
     }
@@ -50,7 +50,7 @@ while (i < old#) {
 output[i] = 1;
 return output;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return []u8;", code.print());
         assertEquals("\u0001", Eval2.eval(code,  0));
     }
@@ -62,7 +62,7 @@ return output;
 int[] is = new int[2];
 return is[1];
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 0;", code.print());
         assertEquals("0", Eval2.eval(code,  0));
     }
@@ -75,7 +75,7 @@ int[] is = new int[2];
 int[] is2 = new int[2];
 return is[1];
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 0;", code.print());
         assertEquals("0", Eval2.eval(code,  0));
     }
@@ -89,7 +89,7 @@ a[0] = 1;
 a[1] = 2;
 return a[0];
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 1;", code.print());
         assertEquals("1", Eval2.eval(code,  0));
     }
@@ -102,7 +102,7 @@ struct _A { int i; };
 !_A?[] !a = new !_A?[2];
 return a;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return []*Test._A?;", code.print());
         assertEquals("*Test._A {i64 !i; }?[ null,null]", Eval2.eval(code, 0));
     }
@@ -131,7 +131,7 @@ else {
 }
 return rez;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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));
@@ -156,7 +156,7 @@ if( iss[arg] )
     if( iss[arg][2] )
         rez = iss[arg][2].y;
 return rez;""");
-        code.parse().iter().opto().iterPostOpto().finalizeIR().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
@@ -174,7 +174,7 @@ root._kids = new !_Tree?[2]; // NO BANG SO ARRAY IS OF IMMUTABLE TREES????
 root._kids[0] = new _Tree;
 return root;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck();
+        code.driver(CodeGen.Phase.TypeCheck);
         assertEquals("return Test._Tree;", code.print());
         assertEquals("Test._Tree{_kids=*Test._Tree {*[]*Test._Tree?[mutable]? !_kids; }?[ Test._Tree{_kids=null},null]}", Eval2.eval(code,  0));
     }
@@ -186,7 +186,7 @@ return root;
 struct _S { int a; int[] !b; new _S = { int[] ary -> b=ary; }; };
 return 0;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 0;", code.print());
     }
 
@@ -209,7 +209,7 @@ while( i < ary# - 1 ) {
 }
 return ary[1] * 1000 + ary[3]; // 1 * 1000 + 6
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck();
+        code.driver(CodeGen.Phase.TypeCheck);
         assertEquals("return (.[]+(.[]*1000));", code.print());
         assertEquals("1006", Eval2.eval(code,  4));
     }
@@ -218,7 +218,7 @@ 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().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return []u32;", code.print());
         assertEquals("u32[ 2,3,5,7,11,13,17,19]",Eval2.eval(code, 20));
     }
@@ -235,7 +235,7 @@ s2.f = 2.0;
 if (arg) s1 = new _S;
 return s1.i + s1.f;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return ((flt).i+.f);", code.print());
         assertEquals("0.0", Eval2.eval(code,  0));
     }
@@ -247,7 +247,7 @@ return s1.i + s1.f;
 """
 return new flt;
 """);
-        try { code.parse().iter().opto().iterPostOpto().finalizeIR(); fail(); }
+        try { code.driver(CodeGen.Phase.FinalizeIR); fail(); }
         catch( Exception e ) { assertEquals("Cannot allocate a flt",e.getMessage()); }
     }
 
@@ -258,7 +258,7 @@ return new flt;
 flt is = new int[2];
 return is;
 """);
-        try { code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck(); fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
         catch( Exception e ) { assertEquals("Type *[]i64 is not of declared type flt",e.getMessage()); }
     }
 
@@ -269,7 +269,7 @@ return is;
 int[] is = new int[3.14];
 return is[1];
 """);
-        try { code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck(); fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
         catch( Exception e ) { assertEquals("Cannot '<<' 3.14",e.getMessage()); }
     }
 
@@ -279,7 +279,7 @@ return is[1];
 int[] is = new int[arg];
 return is[1];
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 0;", code.print());
         assertEquals("0", Eval2.eval(code,  4));
         try { Eval2.eval(code,-1); fail(); }
@@ -312,7 +312,7 @@ while(v5+(0&0)) {
 }
 return v1;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 0;", code.print());
         assertEquals("0", Eval2.eval(code,  0));
     }
@@ -328,7 +328,7 @@ int v8=0;
 while(0<--1>>>---(v7*0==v8)) {}
 return 0;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 0;", code.print());
     }
 
@@ -353,7 +353,7 @@ else {
 }
 return 0;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 0;", code.print());
     }
 }
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/Chapter16Test.java b/chapter25/src/test/java/com/seaofnodes/simple/Chapter16Test.java
index ad9b99bc..2942cfee 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/Chapter16Test.java
+++ b/chapter25/src/test/java/com/seaofnodes/simple/Chapter16Test.java
@@ -15,7 +15,7 @@ public class Chapter16Test {
 """
 return 3.14;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 3.14;", code.print());
         assertEquals("3.14", Eval2.eval(code,  0));
     }
@@ -28,7 +28,7 @@ return 3.14;
 int x, y;
 return x+y;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 0;", code.print());
         assertEquals("0", Eval2.eval(code,  0));
     }
@@ -39,7 +39,7 @@ return x+y;
 int x=2, y=x+1;
 return x+y;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 5;", code.print());
         assertEquals("5", Eval2.eval(code,  0));
     }
@@ -52,7 +52,7 @@ struct _X { int x=3; };
 _X z = new _X;
 return z.x;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 3;", code.print());
         assertEquals("3", Eval2.eval(code,  0));
     }
@@ -64,7 +64,7 @@ struct _X { int x=3; new _X = { int xx -> x=xx; }; };
 _X z = new _X(4);
 return z.x;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 4;", code.print());
         assertEquals("4", Eval2.eval(code,  0));
     }
@@ -85,7 +85,7 @@ _LLI? next = head.next;
 if( !next ) return 1;
 return next.i;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return Phi(Region,1,.i,0);", code.print());
         assertEquals("0", Eval2.eval(code,  0));
         assertEquals("1", Eval2.eval(code,  1));
@@ -115,7 +115,7 @@ _LLI? next = head.next;
 if( !next ) return 1;
 return next.i;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return Phi(Region,1,.i,0);", code.print());
         assertEquals("0", Eval2.eval(code,  0));
         assertEquals("1", Eval2.eval(code,  1));
@@ -140,7 +140,7 @@ struct _Square {
 };
 return new _Square;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return Test._Square;", code.print());
         assertEquals("Test._Square{side=3.0,diag=1.7320508075688772}", Eval2.eval(code,  3));
         assertEquals("Test._Square{side=4.0,diag=2.0}", Eval2.eval(code, 4));
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/Chapter17aTest.java b/chapter25/src/test/java/com/seaofnodes/simple/Chapter17aTest.java
index 95a0fc37..ea7afe56 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/Chapter17aTest.java
+++ b/chapter25/src/test/java/com/seaofnodes/simple/Chapter17aTest.java
@@ -15,7 +15,7 @@ int x=2, y=3;
 if( arg ) { int x = y; x = x*x; y=x; } // Shadow final x
 return y;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return Phi(Region,9,3);", code.print());
         assertEquals("3", Eval2.eval(code, 0));
         assertEquals("9", Eval2.eval(code, 1));
@@ -28,7 +28,7 @@ struct _X { int ~x; new _X = { int xx -> x=xx; }; };
 _X z = new _X(3);
 return z.x;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 3;", code.print());
         assertEquals("3", Eval2.eval(code,  0));
     }
@@ -40,7 +40,7 @@ struct _Point { int ~x, ~y; new _Point = { int xx, int yy -> x=xx; y=yy; }; };
 _Point p = new _Point(3,4);
 return p;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return (const)Test._Point;", code.print());
         assertEquals("Test._Point{x=3,y=4}", Eval2.eval(code,  0));
     }
@@ -53,7 +53,7 @@ struct _Point { int x=3, y=4; new _Point = { int xx, int yy -> x=xx; y=yy; }; };
 p.x++;
 return p;
 """);
-        try { code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck(); fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
         catch( Exception e ) { assertEquals("Cannot modify final field 'x'",e.getMessage()); }
     }
 
@@ -65,7 +65,7 @@ struct _Point { int x=3, y=4; };
 p.x++;
 return p;
 """);
-        try { code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck(); fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
         catch( Exception e ) { assertEquals("Cannot modify final field 'x'",e.getMessage()); }
     }
 
@@ -77,7 +77,7 @@ _Point p = new _Point;
 p.x++;
 return p;
 """);
-        try { code.parse().iter().opto().iterPostOpto().finalizeIR(); fail(); }
+        try { code.driver(CodeGen.Phase.FinalizeIR); fail(); }
         catch( Exception e ) { assertEquals("'Test._Point' is not fully initialized, field 'x' needs to be set in a constructor",e.getMessage()); }
     }
 
@@ -89,7 +89,7 @@ _Point p = new _Point;
 p.x++;
 return p;
 """);
-        try { code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck(); fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
         catch( Exception e ) { assertEquals("Cannot modify final field 'x'",e.getMessage()); }
     }
 
@@ -101,7 +101,7 @@ struct _Point { var x=3; var y=4; };
 p.x++;
 return p;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return Test._Point;", code.print());
         assertEquals("Test._Point{x=4,y=4}", Eval2.eval(code,  0));
     }
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/Chapter17bTest.java b/chapter25/src/test/java/com/seaofnodes/simple/Chapter17bTest.java
index 6137c166..e85ce31d 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/Chapter17bTest.java
+++ b/chapter25/src/test/java/com/seaofnodes/simple/Chapter17bTest.java
@@ -15,7 +15,7 @@ public class Chapter17bTest {
 """
 return 1;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck();
+        code.driver(CodeGen.Phase.TypeCheck);
         assertEquals("return 1;", code.print());
         assertEquals("1", Eval2.eval(code,  0));
     }
@@ -27,7 +27,7 @@ return 1;
         CodeGen code = new CodeGen("""
 return arg++;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return arg;", code.print());
         assertEquals("0", Eval2.eval(code, 0));
     }
@@ -37,7 +37,7 @@ return arg++;
         CodeGen code = new CodeGen("""
 return arg+++arg++;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return ((arg<<1)+1);", code.print());
         assertEquals("1", Eval2.eval(code, 0));
     }
@@ -48,7 +48,7 @@ return arg+++arg++;
 //   -(arg--)-(arg--)
 return -arg---arg--;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return (-((arg<<1)+-1));", code.print());
         assertEquals("1", Eval2.eval(code, 0));
     }
@@ -61,7 +61,7 @@ xs[0]++;
 xs[1]++;
 return xs[0];
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 1;", code.print());
         assertEquals("1", Eval2.eval(code, 2));
     }
@@ -73,7 +73,7 @@ u8[] !xs = new u8[1];
 xs[0]--;
 return xs[0];
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 255;", code.print());
         assertEquals("255", Eval2.eval(code, 2));
     }
@@ -86,7 +86,7 @@ struct _S { u16 x; };
 s.x--;
 return s.x;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 65535;", code.print());
         assertEquals("65535", Eval2.eval(code, 2));
     }
@@ -94,7 +94,7 @@ return s.x;
     @Test
     public void testInc6() {
         CodeGen code = new CodeGen("return --arg;");
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return (arg+-1);", code.print());
         assertEquals("-1", Eval2.eval(code, 0));
     }
@@ -102,7 +102,7 @@ return s.x;
     @Test
     public void testInc7() {
         CodeGen code = new CodeGen("u8 x=0; return --x;");
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 255;", code.print());
         assertEquals("255", Eval2.eval(code, 0));
     }
@@ -110,7 +110,7 @@ return s.x;
     @Test
     public void testInc8() {
         CodeGen code = new CodeGen("int x; x+=2; return x+=3;");
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 5;", code.print());
         assertEquals("5", Eval2.eval(code, 0));
     }
@@ -118,14 +118,14 @@ return s.x;
     @Test
     public void testInc9() {
         CodeGen code = new CodeGen("flt x = 1.5; x++; return x;");
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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().opto().iterPostOpto().finalizeIR().typeCheck();
+        code.driver(CodeGen.Phase.TypeCheck);
         assertEquals("2",Eval2.eval(code,0));
     }
 
@@ -133,73 +133,73 @@ return s.x;
     // ---------------------------------------------------------------
     @Test public void testVar0() {
         CodeGen code = new CodeGen("var d; return d;");
-        try { code.parse().iter().opto().iterPostOpto().finalizeIR(); fail(); }
+        try { code.driver(CodeGen.Phase.FinalizeIR); fail(); }
         catch( Exception e ) { assertEquals("Syntax error, expected `=expression` but found `;`",e.getMessage()); }
     }
 
     @Test public void testVar1() {
         CodeGen code = new CodeGen("val d; return d;");
-        try { code.parse().iter().opto().iterPostOpto().finalizeIR(); fail(); }
+        try { code.driver(CodeGen.Phase.FinalizeIR); fail(); }
         catch( Exception e ) { assertEquals("Syntax error, expected `=expression` but found `;`",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().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 1;", code.print());
         assertEquals("1", Eval2.eval(code, 0));
     }
 
     @Test public void testVar5() {
         CodeGen code = new CodeGen("struct _S{int x; new _S={ int xx -> x=xx; };}; !_S? !s; s=new _S(3); s.x++; return s.x; // Ok, no initializer so x is mutable ");
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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().opto().iterPostOpto().finalizeIR().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; new S={ int xx -> x=xx; };}; ~S s = new S(3); s.x++; return s.x; // Error initializer so x is immutable ");
-        try { code.parse().iter().opto().iterPostOpto().finalizeIR().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().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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().opto().iterPostOpto().finalizeIR().typeCheck(); fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
         catch( Exception e ) { assertEquals("Cannot modify final field 'x'",e.getMessage()); }
     }
 
@@ -218,7 +218,7 @@ foo.bar.x++;   // Ok foo and foo.bar and foo.bar.x are all mutable
 xfoo.bar.x++;   // Error, cannot mutate through xfoo
 return xfoo.bar.x;
  """);
-        try { code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck(); fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
         catch( Exception e ) { assertEquals("Cannot modify final field 'x'",e.getMessage()); }
     }
 
@@ -239,7 +239,7 @@ 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().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 45;", code.print());
         assertEquals("45", Eval2.eval(code, 0));
     }
@@ -249,7 +249,7 @@ return x4*10+x5;
         CodeGen code = new CodeGen("""
 int i,i++;
 """);
-        try { code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck(); fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
         catch( Exception e ) { assertEquals("Redefining name 'i'",e.getMessage()); }
     }
 
@@ -264,7 +264,7 @@ struct A { !B !b; new A = { ->
 }; };
 A x = new A;
 """);
-        try { code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck(); fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
         catch( Exception e ) { assertEquals("Field 'b' might not be initialized",e.getMessage()); }
     }
 
@@ -296,7 +296,7 @@ A x = new A;
             "!B !b; new A = { -> if (arg) { b = new B; return 0; } b = new B; };",
         } ) {
             CodeGen code = new CodeGen("struct B {}; struct A { "+fields+" }; return new A.b != null;");
-            code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck();
+            code.driver(CodeGen.Phase.TypeCheck);
             assertEquals("1",Eval2.eval(code,0));
             assertEquals("1",Eval2.eval(code,1));
         }
@@ -314,7 +314,7 @@ val x = 1;
 return x;
 """
 );
-        try { code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck(); fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
         catch( Exception e ) { assertEquals("Undefined name 'x'",e.getMessage()); }
     }
 
@@ -343,7 +343,7 @@ return me;
         CodeGen code = new CodeGen("""
 return arg ? 1 : 2;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return Phi(Region,1,2);", code.print());
         assertEquals("2", Eval2.eval(code, 0));
         assertEquals("1", Eval2.eval(code, 1));
@@ -354,7 +354,7 @@ return arg ? 1 : 2;
         CodeGen code = new CodeGen("""
 return arg ? 0 : arg;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 0;", code.print());
         assertEquals("0", Eval2.eval(code, 0));
     }
@@ -368,7 +368,7 @@ val get = { !S s -> s.x; };
 if( !s || !arg ) return 0;
 return get(s);
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck();
+        code.driver(CodeGen.Phase.TypeCheck);
     }
 
     @Test
@@ -378,7 +378,7 @@ struct _Bar { int x; };
 var b = arg ? new _Bar : null;
 return b ? b.x++ + b.x++ : -1;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return Phi(Region,((.x<<1)+1),-1);", code.print());
         assertEquals("-1", Eval2.eval(code, 0));
 
@@ -392,7 +392,7 @@ struct _Bar { int x; };
 var b = arg ? new _Bar;
 return b ? b.x++ + b.x++ : -1;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return Phi(Region,((.x<<1)+1),-1);", code.print());
         assertEquals("-1", Eval2.eval(code, 0));
         assertEquals("1", Eval2.eval(code, 1));
@@ -406,7 +406,7 @@ struct _Bar { !_Bar? !next; int x; new _Bar = { !_Bar? !n, int xx -> next=n; x=x
 var b = arg ? new _Bar((arg==2) ? new _Bar(null,2), 1);
 return b ? b.next ? b.next.x : b.x; // parses "b ? (b.next ? b.next.x : b.x) : 0"
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return Phi(Region,.x,0,.x);", code.print());
         assertEquals("0", Eval2.eval(code, 0));
         assertEquals("1", Eval2.eval(code, 1));
@@ -419,7 +419,7 @@ 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().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return Phi(Region,1.0f,1.2);", code.print());
         assertEquals("1.2", Eval2.eval(code,  0));
     }
@@ -431,7 +431,7 @@ return f;   // missing widening
 struct S{};
 return arg ? 7 : new S;
 """);
-        try { code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck(); fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
         catch( Exception e ) { assertEquals("Cannot return generic scalar",e.getMessage()); }
     }
 
@@ -444,7 +444,7 @@ for( int i=0; i<arg; i++ )
     sum += i;
 return sum;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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));
@@ -457,7 +457,7 @@ for( ; i<arg; i++ )
     sum += i;
 return sum;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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));
@@ -472,7 +472,7 @@ for( int i=0; ; i++ ) {
 }
 return sum;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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));
@@ -485,7 +485,7 @@ for( int i=0; i<arg; )
     sum += i++;
 return sum;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.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));
@@ -498,7 +498,7 @@ for( int i=0; i<arg; i++ )
     sum += i;
 return i;
 """);
-        try { code.parse().iter().opto().iterPostOpto().finalizeIR(); fail(); }
+        try { code.driver(CodeGen.Phase.FinalizeIR); fail(); }
         catch( Exception e ) { assertEquals("Undefined name 'i'",e.getMessage()); }
     }
     @Test
@@ -506,7 +506,7 @@ return i;
         CodeGen code = new CodeGen("""
 for(;;arg++;) {}
 """);
-        try { code.parse().iter().opto().iterPostOpto().finalizeIR(); fail(); }
+        try { code.driver(CodeGen.Phase.FinalizeIR); fail(); }
         catch( Exception e ) { assertEquals("Syntax error, expected `Unexpected code after expression` but found `;`",e.getMessage()); }
     }
 
@@ -522,7 +522,7 @@ struct _A {
 };
 return new _A;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return Test._A;", code.print());
         assertEquals("Test._A{f1=null,f2=null}", Eval2.eval(code,0));
     }
@@ -537,7 +537,7 @@ struct _A {
 };
 return new _A(new !B?[0]).array_of_b;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return []*B?;", code.print());
         assertEquals("*B {}?[]", Eval2.eval(code,0));
     }
@@ -556,7 +556,7 @@ for( ; ptr; ptr = ptr.next )
     sum += ptr.i;
 return sum;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return Phi(Loop,0,(Phi_sum+.i));", code.print());
         assertEquals("45", Eval2.eval(code, 10));
     }
@@ -587,7 +587,7 @@ for( int j=0; j<nprimes; j++ )
     rez[j] = primes[j];
 return rez;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck().GCM();
+        code.driver(CodeGen.Phase.FinalizeIR).driver(CodeGen.Phase.Schedule);
         assertEquals("return []i64;", code.print());
         assertEquals("i64[ 2,3,5,7,11,13,17,19]",Eval2.eval(code, 20));
     }
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/Chapter18Test.java b/chapter25/src/test/java/com/seaofnodes/simple/Chapter18Test.java
index d88d8e9d..ae1dca5f 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/Chapter18Test.java
+++ b/chapter25/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().opto().iterPostOpto().finalizeIR().typeCheck();
+                new CodeGen(test[0]).driver(CodeGen.Phase.TypeCheck);
                 fail("Expected incompatible return types: " + test[0]);
             } catch( Parser.ParseException e ) {
                 assertEquals("Cannot return generic scalar",e.getMessage());
@@ -140,7 +140,7 @@ while(arg--) {
 }
 return a;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck();
+        code.driver(CodeGen.Phase.TypeCheck);
         assertEquals("return Phi(Loop,1,Phi(Loop,2,Phi_a));", code.print());
         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().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return null;", code.print());
         assertEquals("null", Eval2.eval(code, 0 ) );
     }
@@ -170,7 +170,7 @@ return x2;
     x*x;
 };
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("Stop[ return { sq}; return (Parm_x(sq,i64)*x); ]", code.print());
         assertEquals("{ ptr i64 -> i64 #[ 3]}", Eval2.eval(code, 3));
     }
@@ -197,7 +197,7 @@ return _sq(arg)+_sq(3);
 int cnt=1;                      // Global scope; exactly one of these
 return { -> cnt++; };           // Escape global-scope variable is OK
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("Stop[ return { ptr -> i64 #[ 3]}; return .cnt; ]", code.print());
         assertEquals("{ ptr -> i64 #[ 3]}", Eval2.eval(code, 0));
     }
@@ -216,7 +216,7 @@ val B = ctr();                  // Make a counter
 A();                            // Increment counter A
 return A()*10 + B();            // Incr A and B; result: 2*10+1 == 21
 """);
-        try { code.parse().iter().opto().iterPostOpto().finalizeIR(); fail(); }
+        try { code.driver(CodeGen.Phase.FinalizeIR); fail(); }
         catch( Exception e ) { assertEquals("Variable 'cnt' is out of function scope and must be a final constant",e.getMessage()); }
     }
 
@@ -228,7 +228,7 @@ return A()*10 + B();            // Incr A and B; result: 2*10+1 == 21
 val cnt=2;
 return { -> cnt; }();
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return 2;", code.print());
         assertEquals("2", Eval2.eval(code, 0));
     }
@@ -241,7 +241,7 @@ return { -> cnt; }();
 var fcn = arg ? { int x -> x*x; } : { int x -> x+x; };
 return fcn(3);
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("Stop[ return #2; return (Parm_x($fun3,i64,3)*x); return (Parm_x($fun4,i64,3)<<1); ]", code.print());
         assertEquals("6", Eval2.eval(code, 0));
         assertEquals("9", Eval2.eval(code, 1));
@@ -251,7 +251,7 @@ 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().opto().iterPostOpto().finalizeIR().typeCheck();
+        code.driver(CodeGen.Phase.TypeCheck);
         String ir = code.print();
         assertTrue(ir.equals("Stop[ return #2; return Phi(Region,1,(Parm_x(_fact,arg,(x-1))*#2)); ]") ||
                    ir.equals("Stop[ return Phi(Region,1,(arg*#2)); return Phi(Region,1,(Parm_x(_fact,(arg-1),(x-1))*#2)); ]") ||
@@ -269,7 +269,7 @@ return fcn(3);
     @Test
     public void testFcn5Float() {
         CodeGen code = new CodeGen("val _fact = { int x -> x <= 1 ? 1.0 : x*_fact(x-1); }; return _fact(arg);");
-        code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck();
+        code.driver(CodeGen.Phase.TypeCheck);
         assertEquals("1.0",  Eval2.eval(code, 0));
         assertEquals("1.0",  Eval2.eval(code, 1));
         assertEquals("2.0",  Eval2.eval(code, 2));
@@ -280,7 +280,7 @@ return fcn(3);
     @Test
     public void testFcn5Minus() {
         CodeGen code = new CodeGen("val _neg = { int x -> x ? -_neg(x-1) : 1; }; return _neg(arg);");
-        code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck();
+        code.driver(CodeGen.Phase.TypeCheck);
         assertEquals( "1", Eval2.eval(code, 0));
         assertEquals("-1", Eval2.eval(code, 1));
         assertEquals( "1", Eval2.eval(code, 2));
@@ -295,7 +295,7 @@ struct _S { int i; new _S = { int x -> i=x; }; };
 val _newS = { int x -> return new _S(x); };
 return _newS(1).i;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck();
+        code.driver(CodeGen.Phase.TypeCheck);
         assertEquals("return 1;", code.print());
         assertEquals("1", Eval2.eval(code,  0));
     }
@@ -310,7 +310,7 @@ val _g = {->2;};
 if( arg ? _f : _g ) return 1;
 return 2;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck();
+        code.driver(CodeGen.Phase.TypeCheck);
         assertEquals("return 1;", code.print());
         assertEquals("1", Eval2.eval(code,  0));
     }
@@ -388,7 +388,7 @@ for(;;) {
 }
 return 1;
 """);
-        try { code.parse().iter().opto().iterPostOpto().finalizeIR(); fail(); }
+        try { code.driver(CodeGen.Phase.FinalizeIR); fail(); }
         catch( Exception e ) { assertEquals("No active loop for a break or continue",e.getMessage()); }
     }
 
@@ -404,7 +404,7 @@ for(;;) {
 }
 return 0;
 """);
-        try { code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck(); fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
         catch( Exception e ) { assertEquals("Might be null calling { ptr i64 -> i64 #[ 3]}?",e.getMessage()); }
     }
 
@@ -416,7 +416,7 @@ return 0;
 val f = { int i, int j -> return i+j; };
 return f();
 """);
-        try { code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck(); fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
         catch( Exception e ) { assertEquals("Expecting 3 arguments, but found 1",e.getMessage()); }
     }
 
@@ -432,7 +432,7 @@ val x = { -> return 1; };
 S? s = new S;
 return s.x;
 """);
-        try { code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck(); fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
         catch( Exception e ) { assertEquals("Accessing unknown field 'x' from '*Test.S'",e.getMessage()); }
     }
 
@@ -445,7 +445,7 @@ val g = { ->
 };
 return g();
 """);
-        try { code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck(); fail(); }
+        try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
         catch( Exception e ) { assertEquals("No defined return type",e.getMessage()); }
     }
 
@@ -459,7 +459,7 @@ 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().opto().iterPostOpto().finalizeIR().typeCheck();
+        code.driver(CodeGen.Phase.TypeCheck);
         assertEquals("Stop[ return #2; return Phi(Region,0,1,#2); ]", code.print());
         assertEquals("1", Eval2.eval(code, 0));
         assertEquals("0", Eval2.eval(code, 1));
@@ -481,7 +481,7 @@ for(;;) {
     if (s) return s.f;
 }
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck().GCM();
+        code.driver(CodeGen.Phase.FinalizeIR).driver(CodeGen.Phase.Schedule);
         assertEquals("return 0;", code.print());
         assertEquals("0", Eval2.eval(code,  0));
     }
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/Chapter19Test.java b/chapter25/src/test/java/com/seaofnodes/simple/Chapter19Test.java
index 2763e53d..6f290279 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/Chapter19Test.java
+++ b/chapter25/src/test/java/com/seaofnodes/simple/Chapter19Test.java
@@ -37,7 +37,7 @@ public class Chapter19Test {
         CodeGen code = new CodeGen("""
 return 0;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck();
+        code.driver(CodeGen.Phase.TypeCheck);
         assertEquals("return 0;", code.print());
         assertEquals("0", Eval2.eval(code,  2));
     }
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/Chapter20Test.java b/chapter25/src/test/java/com/seaofnodes/simple/Chapter20Test.java
index 9f537fe7..0458941e 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/Chapter20Test.java
+++ b/chapter25/src/test/java/com/seaofnodes/simple/Chapter20Test.java
@@ -69,7 +69,7 @@ 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,seed,true).parse().iter().opto().iterPostOpto().finalizeIR().typeCheck();
+            CodeGen code = new CodeGen(src,seed,true).driver(CodeGen.Phase.TypeCheck);
             assertEquals("seed "+seed, "123", Eval2.eval(code,0));
         }
     }
@@ -92,7 +92,7 @@ return f(s);
     @Test
     public void testJig() {
         CodeGen code = new CodeGen("return 0;");
-        code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck();
+        code.driver(CodeGen.Phase.TypeCheck);
         assertEquals("return 0;", code.print());
         assertEquals("0", Eval2.eval(code,  2));
     }
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/Chapter21Test.java b/chapter25/src/test/java/com/seaofnodes/simple/Chapter21Test.java
index 83342ab8..07ae42eb 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/Chapter21Test.java
+++ b/chapter25/src/test/java/com/seaofnodes/simple/Chapter21Test.java
@@ -48,7 +48,7 @@ public class Chapter21Test {
                 else if(i==4) b.x=40;
             }
             return sum;
-            """).parse().iter().opto().iterPostOpto().finalizeIR();
+            """).driver(CodeGen.Phase.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));
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/Chapter22Test.java b/chapter25/src/test/java/com/seaofnodes/simple/Chapter22Test.java
index cbb08438..00d77f65 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/Chapter22Test.java
+++ b/chapter25/src/test/java/com/seaofnodes/simple/Chapter22Test.java
@@ -88,7 +88,7 @@ public class Chapter22Test {
 
     @Test public void testSubZeroTypeError() {
         try {
-            new CodeGen("return null-0;").parse().iter().opto().iterPostOpto().finalizeIR().typeCheck();
+            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 - 0",e.getMessage());
@@ -283,7 +283,7 @@ aa.c = cc;
 bb.c = cc;
 return cc.cz;
 """;
-        CodeGen code = new CodeGen(src).parse().iter().opto().iterPostOpto().finalizeIR().typeCheck();
+        CodeGen code = new CodeGen(src).driver(CodeGen.Phase.TypeCheck);
         assertEquals("return 25;", code.print());
         assertEquals("25", Eval2.eval(code, 0));
     }
@@ -322,7 +322,7 @@ return 0;
     @Test
     public void testStrLoad() {
         CodeGen code = new CodeGen("return \"abc\"[1];");
-        code.parse().iter().opto().iterPostOpto().finalizeIR();
+        code.driver(CodeGen.Phase.FinalizeIR);
         assertEquals("return .[];", code.print());
     }
 
@@ -342,7 +342,7 @@ val _sum = { i32[~] is ->  // final array
 };
 return _sum(is);
 """;
-        CodeGen code = new CodeGen(src).parse().iter().opto().iterPostOpto().finalizeIR().typeCheck();
+        CodeGen code = new CodeGen(src).driver(CodeGen.Phase.TypeCheck);
         assertEquals("return Phi(Loop,0,(Phi_sum+.[]));", code.print());
         assertEquals("14", Eval2.eval(code, 0));
     }
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/Chapter23Test.java b/chapter25/src/test/java/com/seaofnodes/simple/Chapter23Test.java
index b5da4d91..df02d3b4 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/Chapter23Test.java
+++ b/chapter25/src/test/java/com/seaofnodes/simple/Chapter23Test.java
@@ -120,10 +120,10 @@ return a && b ? 0 : 1;  // Expected answer 0
 
     @Test
     public void testLogicalValueSemantics() {
-        assertEquals("42", Eval2.eval(new CodeGen("return 7 && 42;").parse().iter().opto().iterPostOpto().finalizeIR(), 0));
-        assertEquals("0",  Eval2.eval(new CodeGen("return 0 && 42;").parse().iter().opto().iterPostOpto().finalizeIR(), 0));
-        assertEquals("7",  Eval2.eval(new CodeGen("return 7 || 42;").parse().iter().opto().iterPostOpto().finalizeIR(), 0));
-        assertEquals("42", Eval2.eval(new CodeGen("return 0 || 42;").parse().iter().opto().iterPostOpto().finalizeIR(), 0));
+        assertEquals("42", Eval2.eval(new CodeGen("return 7 && 42;").driver(CodeGen.Phase.FinalizeIR), 0));
+        assertEquals("0",  Eval2.eval(new CodeGen("return 0 && 42;").driver(CodeGen.Phase.FinalizeIR), 0));
+        assertEquals("7",  Eval2.eval(new CodeGen("return 7 || 42;").driver(CodeGen.Phase.FinalizeIR), 0));
+        assertEquals("42", Eval2.eval(new CodeGen("return 0 || 42;").driver(CodeGen.Phase.FinalizeIR), 0));
     }
 
     @Test
@@ -133,7 +133,7 @@ struct S {};
 S? s = arg ? new S;
 return !(!s || !arg) ? 1 : 0;
 """);
-        code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck();
+        code.driver(CodeGen.Phase.TypeCheck);
         assertEquals("0", Eval2.eval(code, 0));
         assertEquals("1", Eval2.eval(code, 1));
     }
@@ -146,7 +146,7 @@ struct S { !S? !fld; new S = { !S? f -> fld=f; }; };
 val ptr = arg == 1 ? null : new S(arg==1 ? null : new S(null));
 return ptr && ptr.fld ? "true" : "false";
 """;
-        CodeGen code = new CodeGen(src).parse().iter().opto().iterPostOpto().finalizeIR().typeCheck();
+        CodeGen code = new CodeGen(src).driver(CodeGen.Phase.TypeCheck);
         assertEquals("true", Eval2.eval(code, 0));
 
         // Evaluate on RISC5 emulator
@@ -276,7 +276,7 @@ struct _Scan {
 return _s.peek('q');
 """;
 
-        CodeGen code = new CodeGen(src).parse().iter().opto().iterPostOpto().finalizeIR().typeCheck();
+        CodeGen code = new CodeGen(src).driver(CodeGen.Phase.TypeCheck);
         assertEquals("return Phi(Region,0,1);", code.print());
         assertEquals("1", Eval2.eval(code, 0));
         testCPU(src,"x86_64_v2", "win64",23,null);
@@ -301,7 +301,7 @@ struct _Scan {
 return s.skip().x;
 """;
 
-        try { new CodeGen(src).parse().iter().opto().iterPostOpto().finalizeIR().typeCheck(); fail(); }
+        try { new CodeGen(src).driver(CodeGen.Phase.TypeCheck); fail(); }
         catch( Exception e ) {
             // Bad error message, but basically requires a mutable 'x' field.
             org.junit.Assert.assertTrue(e.getMessage().startsWith("Argument #0 isa"));
@@ -331,7 +331,7 @@ struct _Scan {
 return _s.require('[');
 """;
 
-        CodeGen code = new CodeGen(src).parse().iter().opto().iterPostOpto().finalizeIR().typeCheck();
+        CodeGen code = new CodeGen(src).driver(CodeGen.Phase.TypeCheck);
         assertEquals("return (.[]==91);", code.print());
         assertEquals("1", Eval2.eval(code, 0));
         testCPU(src,"x86_64_v2", "win64",4, null);
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/Chapter24Test.java b/chapter25/src/test/java/com/seaofnodes/simple/Chapter24Test.java
index 4bfb0d30..2f125ed0 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/Chapter24Test.java
+++ b/chapter25/src/test/java/com/seaofnodes/simple/Chapter24Test.java
@@ -257,7 +257,7 @@ while (cnt) {
 }
 return x;
 """;
-        CodeGen code = new CodeGen(src).parse().iter().opto().iterPostOpto().finalizeIR().typeCheck();
+        CodeGen code = new CodeGen(src).driver(CodeGen.Phase.TypeCheck);
         assertEquals("return 1;", code.print());
     }
 
@@ -272,7 +272,7 @@ while( cnt-- )
     x = 2-x;
 return x;
 """;
-        CodeGen code = new CodeGen(src).parse().iter().opto().iterPostOpto().finalizeIR().typeCheck();
+        CodeGen code = new CodeGen(src).driver(CodeGen.Phase.TypeCheck);
         assertEquals("return 1;", code.print());
     }
 
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/Chapter25Test.java b/chapter25/src/test/java/com/seaofnodes/simple/Chapter25Test.java
index 4e8effbe..275be96a 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/Chapter25Test.java
+++ b/chapter25/src/test/java/com/seaofnodes/simple/Chapter25Test.java
@@ -28,6 +28,36 @@ import static org.junit.Assert.*;
 
 public class Chapter25Test {
 
+    @Test public void testFlagSpills() throws IOException {
+        com.seaofnodes.simple.codegen.FlagSpillTestSupport.run();
+    }
+
+    @Ignore
+    @Test
+    public void testJig() {
+        String src = "{ i32 -> i32 } close = \"C\"; val main = { u8[] a -> if (a# > 1) return close(0);  return a[0]; };";
+        CodeGen code = new CodeGen(src).driver(CodeGen.Phase.Encoding,"riscv","SystemV");
+        assertEquals("return (arg+3);", code.print());
+        assertEquals("3",Eval2.eval(code,0));
+    }
+
+    @Test public void testConditionalClassInitX86() throws IOException {
+        Path build=Path.of("build/objs");
+        Files.createDirectories(build);
+        Path dir=Files.createTempDirectory(build,"init_flags_");
+        // Keep B separately compiled so its first-touch check survives.
+        new CodeGen(null,dir.toString(),null,"B","int value=17+arg;",123,true,TypeInteger.BOT)
+            .driver("x86_64_v2","win64",false,false);
+        // GCM can hoist the fused B.$init compare above the test of take.
+        // Its flags then cross another flag definition and need a legal split.
+        new CheckedCodeGen(null,dir.toString(),new Ary<>(new String[]{dir.toString()}),
+            "Main","val run={int take -> return take ? B.value : 0; };",123,true,TypeInteger.BOT)
+            .driver(CodeGen.Phase.Encoding,"x86_64_v2","win64");
+        // Remove successful fixtures; preserve the object if compilation fails.
+        Files.delete(dir.resolve("B.o"));
+        Files.delete(dir);
+    }
+
     @Test public void testPublicInstanceMethod() {
         String src = """
             struct Scan {
@@ -63,15 +93,6 @@ public class Chapter25Test {
         }
     }
 
-    @Ignore
-    @Test
-    public void testJig() {
-        String src = "int x = arg/17; if( arg == 0 ) return arg + x; return arg + x;";
-        CodeGen code = new CodeGen(src).driver(CodeGen.Phase.TypeCheck);
-        assertEquals("return (arg+3);", code.print());
-        assertEquals("3",Eval2.eval(code,0));
-    }
-
     @Test public void testNeverReturnPointerRiscV() {
         new CodeGen("""
             struct _S { int x; };
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/ClassInitDependenciesTest.java b/chapter25/src/test/java/com/seaofnodes/simple/ClassInitDependenciesTest.java
index cc010668..47e10f97 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/ClassInitDependenciesTest.java
+++ b/chapter25/src/test/java/com/seaofnodes/simple/ClassInitDependenciesTest.java
@@ -433,6 +433,88 @@ public class ClassInitDependenciesTest {
         assertEquals(1,stores[0]);
     }
 
+    @Test public void testInitializationExecution() throws Exception {
+        Path dir=tempDir("execution-");
+        object(dir,dir,"State","int count=0;");
+        object(dir,dir,"B","State.count++; int value=17+arg;");
+        String src="int value=arg ? B.value+B.value : 0; return value+100*State.count;";
+        for( long seed : new long[]{1,123,987654321} ) {
+            CodeGen code=new CodeGen(null,dir.toString(),new Ary<>(new String[]{dir.toString()}),
+                "Main",src,seed,true,TypeInteger.BOT).driver(CodeGen.Phase.TypeCheck);
+            assertNotNull(code._stop.walk(n -> n instanceof CLInitNode ? n : null));
+            assertEquals("0",Eval2.eval(code,0));
+            assertNull(code._stop.walk(n -> n instanceof CLInitNode ? n : null));
+            assertEquals("134",Eval2.eval(code,1));
+        }
+
+        object(dir,dir,"Main","val run={int take -> "+src.replace("arg ?","take ?")+" };");
+        Path cfile=dir.resolve("check.c");
+        Files.writeString(cfile,"""
+            #include <stdint.h>
+            __attribute__((CALL_CONV)) extern int64_t run(int64_t take);
+            int main(void) {
+                return run(0)!=0 || run(1)!=134 || run(1)!=134 || run(0)!=100;
+            }
+            """);
+        String exe=dir.resolve(TestC.OS.startsWith("Windows") ? "check.exe" : "check").toString();
+        TestC.linkExe(dir.resolve("Main.o").toString(),TestC.CALL_CONVENTION.equals("win64") ? "ms_abi" : "sysv_abi",
+            cfile.toString(),new Ary<>(new String[]{dir.resolve("B.o").toString(),dir.resolve("State.o").toString()}),exe);
+        assertEquals("",TestC.exec(exe));
+        for( String cpu : new String[]{"arm","riscv"} )
+            new CodeGen(null,dir.toString(),new Ary<>(new String[]{dir.toString()}),
+                "Main",src,123,true,TypeInteger.BOT).driver(CodeGen.Phase.Encoding,cpu,"SystemV");
+    }
+
+    @Test public void testParentInitializationExecution() throws Exception {
+        Path dir=tempDir("execution-");
+        object(dir,dir,"State","int count=0;");
+        module(dir,dir,"P",Map.of("P","val C=C; State.count=State.count*10+1;",
+            "P/C","State.count=State.count*10+2; int value=arg;"));
+        for( long seed : new long[]{1,123,987654321} ) {
+            CodeGen code=new CodeGen(null,dir.toString(),new Ary<>(new String[]{dir.toString()}),
+                "Main","return P.C.value+State.count;",seed,true,TypeInteger.BOT).driver(CodeGen.Phase.TypeCheck);
+            assertEquals("12",Eval2.eval(code,99));
+        }
+        object(dir,dir,"Main","val run={ -> P.C.value+State.count; };");
+        Path cfile=dir.resolve("check.c");
+        Files.writeString(cfile,"""
+            #include <stdint.h>
+            __attribute__((CALL_CONV)) extern int64_t run(void);
+            int main(void) { return run()!=12 || run()!=12; }
+            """);
+        String exe=dir.resolve(TestC.OS.startsWith("Windows") ? "check.exe" : "check").toString();
+        TestC.linkExe(dir.resolve("Main.o").toString(),TestC.CALL_CONVENTION.equals("win64") ? "ms_abi" : "sysv_abi",
+            cfile.toString(),new Ary<>(new String[]{dir.resolve("P.o").toString(),dir.resolve("State.o").toString()}),exe);
+        assertEquals("",TestC.exec(exe));
+    }
+
+    @Test public void testNonreturningObject() throws Exception {
+        Path dir=tempDir("nonreturning-");
+        object(dir,dir,"Spin","val spin_noInline={ -> while(1) {} return 7; };");
+        CodeGen code=new CodeGen(null,dir.toString(),new Ary<>(new String[]{dir.toString()}),
+            "Main","Spin.spin_noInline(); return 7;",123,true,TypeInteger.BOT).driver(CodeGen.Phase.TypeCheck);
+        assertNull(Eval2.eval(code,0,10));
+    }
+
+    @Test public void testImportedPrivateInitializer() throws Exception {
+        Path dir=tempDir("private-");
+        module(dir,dir,"Library",Map.of("Library","val read={ -> _Hidden.value; };",
+            "Library/_Hidden","int value=17+arg;"));
+        CodeGen code=new CodeGen(null,dir.toString(),new Ary<>(new String[]{dir.toString()}),
+            "Main","return Library.read();",123,true,TypeInteger.BOT).driver(CodeGen.Phase.TypeCheck);
+        assertEquals("17",Eval2.eval(code,99));
+        // Even a request stopping at Select must drop imported bodies. They
+        // remain available only to the ideal evaluator above, not this object.
+        for( String cpu : new String[]{"x86_64_v2","arm","riscv"} ) {
+            CodeGen selected=new CodeGen(null,dir.toString(),new Ary<>(new String[]{dir.toString()}),
+                "Main","return Library.read();",123,true,TypeInteger.BOT).driver(CodeGen.Phase.Select,cpu,"SystemV");
+            assertNull(selected._serial);
+            for( CompUnit cu : selected._compunits.values() )
+                if( cu._src==null ) assertNull(cu._stop);
+            selected.driver(CodeGen.Phase.Encoding,cpu,"SystemV");
+        }
+    }
+
     @Test public void testOverlappingFunctionAndClassCycles() throws Exception {
         // Fixed function graph: Opto/inlining must not erase the overlap that
         // exercises SCC traversal. One clinit is legal, two in the SCC are not.
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/CompoundAssignmentTest.java b/chapter25/src/test/java/com/seaofnodes/simple/CompoundAssignmentTest.java
index db41363a..e2d822d0 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/CompoundAssignmentTest.java
+++ b/chapter25/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().opto().iterPostOpto().finalizeIR().typeCheck();
+        var code = new CodeGen(src).driver(CodeGen.Phase.TypeCheck);
         assertEquals(src, Long.toString(expected), Eval2.eval(code, arg));
     }
 }
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/Eval2.java b/chapter25/src/test/java/com/seaofnodes/simple/Eval2.java
index 21e677ce..366bd7f4 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/Eval2.java
+++ b/chapter25/src/test/java/com/seaofnodes/simple/Eval2.java
@@ -114,6 +114,9 @@ public abstract class Eval2 {
     // Current active Frame, to avoid having to pass it everywhere
     public static Frame F;
 
+    // Class pointers and initializer self parameters share one object per run.
+    private static final HashMap<String,Object[]> CLASSES = new HashMap<>();
+
     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
@@ -122,6 +125,7 @@ public abstract class Eval2 {
         code.driver(CodeGen.Phase.LocalSched);
         // Set global, so don't have to pass everywhere
         CODE = code;
+        CLASSES.clear();
 
         // Timer for when we run too long.  Ticks once per backedge or function call
         int loopCnt = 0;
@@ -140,7 +144,7 @@ public abstract class Eval2 {
                 TypeStruct clz = ((TypeMemPtr)fun.sig().arg(0))._obj;
                 // Map from the <clinit> self parameter to the
                 // singleton class structure.
-                F.put(fun.parm(2),alloc(clz));
+                F.put(fun.parm(2),classObject(clz));
             }
 
 
@@ -203,9 +207,9 @@ public abstract class Eval2 {
 
             // Parms read from Call args -
             // - except RPC is the actual prior frame
-            // - except <clinit> takes the singleton class object and external args
+            // - except entry <clinit> takes the external program argument
             Object val;
-            if( isClz && phi instanceof ParmNode parm && parm._idx==3 )
+            if( isClz && prior instanceof StartNode && phi instanceof ParmNode parm && parm._idx==3 )
                 PHICACHE[i] = arg; // Reading the initial arguments to <clinit>
             else {
                 Node n = phi instanceof ParmNode parm
@@ -349,6 +353,8 @@ public abstract class Eval2 {
                     yield new Object[0];
                 }
 
+            } else if( Parser.startsClzPrefix(tmp._obj._name) ) {
+                yield classObject(tmp._obj);
             } else {
                 // Constant object with all zeros
                 yield alloc(tmp._obj);
@@ -417,6 +423,12 @@ public abstract class Eval2 {
         return ptr;
     }
 
+    private static Object[] classObject(TypeStruct type) {
+        Object[] ptr = CLASSES.get(type._name);
+        if( ptr==null ) CLASSES.put(type._name,ptr=alloc(type));
+        return ptr;
+    }
+
     private static Object not( NotNode not ) {
         Object n = val(not.in(1));
         return ( n==null || (n instanceof Double D && D==0.0) || n instanceof Long L && L==0 )
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/Main.java b/chapter25/src/test/java/com/seaofnodes/simple/Main.java
index 97129f5b..1248a6cf 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/Main.java
+++ b/chapter25/src/test/java/com/seaofnodes/simple/Main.java
@@ -11,7 +11,7 @@ public class Main {
         String src = Files.readString(Path.of(args[0]));
         int arg = Integer.valueOf(args[1]);
         CodeGen code = new CodeGen(src);
-        code.parse().iter().opto().iterPostOpto().finalizeIR().typeCheck().GCM().localSched();
+        code.driver(CodeGen.Phase.FinalizeIR).driver(CodeGen.Phase.Schedule).localSched();
         System.out.println(code._stop);
         System.out.println(Eval2.eval(code,arg,100000));
     }
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/MemoryEncodingTest.java b/chapter25/src/test/java/com/seaofnodes/simple/MemoryEncodingTest.java
index 4934c91f..adeba136 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/MemoryEncodingTest.java
+++ b/chapter25/src/test/java/com/seaofnodes/simple/MemoryEncodingTest.java
@@ -58,7 +58,7 @@ public class MemoryEncodingTest {
         // Exercise both unresolved Store aliases and nested value-Phi cleanup.
         for( long seed : new long[]{0,9,126} )
             for( int p=0; p<sources.length; p++ ) {
-                CodeGen code=new CodeGen(sources[p],seed,true).parse().iter().opto().iterPostOpto().finalizeIR();
+                CodeGen code=new CodeGen(sources[p],seed,true).driver(CodeGen.Phase.FinalizeIR);
                 if( p==0 ) assertNull(code._stop.walk(n ->
                     n instanceof LoadNode ld && ld.ptr() instanceof ProjNode ptr &&
                     ptr.in(0) instanceof NewNode nn &&
@@ -86,7 +86,7 @@ public class MemoryEncodingTest {
             if (arg>1) { v=p.x; p.x=41; p.y=5; }
             else       { v=q.x; q.x=42; }
             return v;
-            """).parse().iter().opto().iterPostOpto().finalizeIR();
+            """).driver(CodeGen.Phase.FinalizeIR);
         StopNode stop = code._stop;
         assertEquals(2,countMemoryNodes(stop,LoadNode.class,new BitSet()));
         assertEquals("-1",Eval2.eval(code,-1));
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/MutabilityTest.java b/chapter25/src/test/java/com/seaofnodes/simple/MutabilityTest.java
index 9727857e..8bd77c06 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/MutabilityTest.java
+++ b/chapter25/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().opto().iterPostOpto().finalizeIR().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().opto().iterPostOpto().finalizeIR().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/chapter25/src/test/java/com/seaofnodes/simple/PhaseTest.java b/chapter25/src/test/java/com/seaofnodes/simple/PhaseTest.java
new file mode 100644
index 00000000..7252378a
--- /dev/null
+++ b/chapter25/src/test/java/com/seaofnodes/simple/PhaseTest.java
@@ -0,0 +1,64 @@
+package com.seaofnodes.simple;
+
+import com.seaofnodes.graph.GraphObserver;
+import com.seaofnodes.simple.codegen.CodeGen;
+import com.seaofnodes.simple.codegen.CodeGen.Phase;
+import com.seaofnodes.simple.node.Node;
+import java.util.ArrayList;
+import org.junit.Test;
+import static org.junit.Assert.*;
+
+public class PhaseTest {
+    private static final String SRC = "int sum=0; for(int i=0; i<arg; i++) sum+=i; return sum;";
+
+    @Test public void testIdealPhasesAndResume() {
+        ArrayList<String> phases = new ArrayList<>();
+        CodeGen code = new CodeGen(SRC);
+        code._obs = new GraphObserver<Node>() {
+            @Override public void before(Node n) {}
+            @Override public void after(Node n, Node repl, boolean applied) {}
+            @Override public void phase(String phase) { phases.add(phase); }
+        };
+        code.driver(Phase.TypeCheck);
+        code.driver(Phase.TypeCheck); // A repeated request does not rerun anything.
+        code.driver(Phase.LocalSched);
+        assertEquals("Parse Iter Opto IterPostOpto FinalizeIR TypeCheck Lower LoopTree Unlink Schedule LocalSched",
+                     String.join(" ",phases));
+        assertNull(code._serial);
+        assertNull(code._mach);
+        assertEquals("45",Eval2.eval(code,10));
+    }
+
+    @Test public void testEncodingWithoutSerialization() {
+        for( String cpu : new String[]{"x86_64_v2","arm","riscv"} ) {
+            CodeGen code = new CodeGen(SRC).driver(Phase.TypeCheck);
+            code.driver(Phase.Unlink,cpu,"SystemV");
+            code.driver(Phase.Select,cpu,"SystemV");
+            code.driver(Phase.Encoding,cpu,"SystemV");
+            assertNull(code._serial);
+            byte[] staged = code._encoding._bits.toByteArray();
+            CodeGen direct = new CodeGen(SRC).driver(Phase.Encoding,cpu,"SystemV");
+            assertArrayEquals(staged,direct._encoding._bits.toByteArray());
+        }
+    }
+
+    @Test public void testExplicitSerializationAndMemoryExport() {
+        CodeGen code = new CodeGen(SRC).driver(Phase.Serialize);
+        assertNotNull(code._serial);
+        assertEquals(Phase.Serialize,code._phase);
+        code.driver(Phase.Encoding,"riscv","SystemV");
+        assertNotNull(code._serial);
+
+        CodeGen memory = new CodeGen(SRC).driver("riscv","SystemV",true,false);
+        assertNull(memory._serial);
+        assertEquals(Phase.Export,memory._phase);
+
+        CodeGen late = new CodeGen(SRC).driver(Phase.Encoding,"riscv","SystemV");
+        try {
+            late.exportELF(false,false);
+            fail("Cannot recover ideal IR after lowering and instruction selection");
+        } catch( IllegalStateException expected ) {
+            assertTrue(expected.getMessage().contains("Serialize before Lower"));
+        }
+    }
+}
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/Simple.java b/chapter25/src/test/java/com/seaofnodes/simple/Simple.java
index 9078a33a..2d688bbe 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/Simple.java
+++ b/chapter25/src/test/java/com/seaofnodes/simple/Simple.java
@@ -49,6 +49,7 @@ Options:
   --dump-after-iter-post-opto - dump after SCCP-driven peepholes and inlining
   --dump-after-finalize-ir - dump after field layout and IR finalization
   --dump-after-type-check  - dump intermediate representation after type check pass
+  --dump-after-lower       - dump expanded class initialization before loop trees
   --dump-after-select      - dump intermediate representation after instruction selection pass
   --dump-after-gcm         - dump intermediate representation after GCM pass
   --dump-after-local-sched - dump intermediate representation after local scheduling pass
@@ -119,6 +120,7 @@ Options:
             case "--dump-after-iter-post-opto": dump |= 1<<Phase.IterPostOpto.ordinal(); break;
             case "--dump-after-finalize-ir":  dump |=  1<<Phase.FinalizeIR.ordinal()   ; break;
             case "--dump-after-type-check":   dump |=  1<<Phase.TypeCheck .ordinal()   ; break;
+            case "--dump-after-lower":        dump |=  1<<Phase.Lower     .ordinal()   ; break;
             case "--dump-after-loop-tree":    dump |=  1<<Phase.LoopTree  .ordinal()   ; break;
             case "--dump-after-select":       dump |=  1<<Phase.Select    .ordinal()   ; break;
             case "--dump-after-gcm":          dump |=  1<<Phase.Schedule  .ordinal()   ; break;
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/StaticDataTest.java b/chapter25/src/test/java/com/seaofnodes/simple/StaticDataTest.java
index 070b7a9e..03df05a7 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/StaticDataTest.java
+++ b/chapter25/src/test/java/com/seaofnodes/simple/StaticDataTest.java
@@ -2,6 +2,9 @@ package com.seaofnodes.simple;
 
 import com.seaofnodes.simple.codegen.CodeGen;
 import com.seaofnodes.simple.codegen.StaticData;
+import com.seaofnodes.simple.node.ConstantNode;
+import com.seaofnodes.simple.node.StoreNode;
+import com.seaofnodes.simple.type.TypeMem;
 import com.seaofnodes.simple.type.TypeStruct;
 import com.seaofnodes.simple.type.TypeInteger;
 import com.seaofnodes.simple.util.Ary;
@@ -16,14 +19,25 @@ public class StaticDataTest {
     private static final String SRC="val n=42; val f={int x -> x+n;}; return 0;";
 
     private static StaticData.ObjectData root(CodeGen code) {
-        return code._encoding._data.entries().stream()
-            .filter(obj -> obj.symbol.endsWith("Test.$class")).findFirst().orElseThrow();
+        for( var obj : code._encoding._data.entries() )
+            if( obj.symbol.endsWith("Test.$class") ) return obj;
+        throw new AssertionError("Missing Test class object");
     }
 
     // Read the image before <clinit>, then call the function through its data slot.
     @Test public void testEmulatorImage() {
         for( String cpu : new String[]{"arm","riscv"} ) {
-            CodeGen code=new CodeGen(SRC).driver(cpu,"SystemV",true,false);
+            CodeGen code=new CodeGen(SRC).driver(CodeGen.Phase.TypeCheck);
+            assertNull("Constant fields fold before instruction selection",
+                       code._stop.walk(n -> n instanceof StoreNode st &&
+                           (st._name.equals("n") || st._name.equals("f")) ? n : null));
+            assertNotNull(code._stop.walk(n -> n instanceof ConstantNode &&
+                n._type instanceof TypeMem mem && mem.isConstant() &&
+                mem._t==TypeInteger.constant(42) ? n : null));
+            assertNotNull("The runtime initialization flag still needs its Store",
+                          code._stop.walk(n -> n instanceof StoreNode st &&
+                              st._name.equals("$init") ? n : null));
+            code.driver(cpu,"SystemV",true,false);
             var e=code._encoding;
             var obj=root(code);
             TypeStruct ts=(TypeStruct)obj.type;
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/codegen/FlagSpillTestSupport.java b/chapter25/src/test/java/com/seaofnodes/simple/codegen/FlagSpillTestSupport.java
new file mode 100644
index 00000000..445acb61
--- /dev/null
+++ b/chapter25/src/test/java/com/seaofnodes/simple/codegen/FlagSpillTestSupport.java
@@ -0,0 +1,141 @@
+package com.seaofnodes.simple.codegen;
+
+import com.seaofnodes.isa.X86;
+import com.seaofnodes.isa.eval.EvalArm64;
+import com.seaofnodes.simple.TestC;
+import com.seaofnodes.simple.node.*;
+import com.seaofnodes.simple.node.cpus.arm.arm;
+import com.seaofnodes.simple.node.cpus.x86_64_v2.x86_64_v2;
+import com.seaofnodes.simple.type.TypeInteger;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import static org.junit.Assert.*;
+
+// Force overlapping flags, then force every GPR unavailable across the gap.
+public class FlagSpillTestSupport {
+    private static class Op extends MachConcreteNode {
+        final RegMask _def, _use, _kill;
+        Op(RegMask def,RegMask use,RegMask kill,Node... ins) {
+            super(ins); _def=def; _use=use; _kill=kill; _type=TypeInteger.BOT;
+        }
+        @Override public String op() { return "flagsProbe"; }
+        @Override public RegMask outregmap() { return _def; }
+        @Override public RegMask regmap(int i) { return _use; }
+        @Override public RegMask killmap() { return _kill; }
+        @Override public void encoding(Encoding enc) { throw new AssertionError(); }
+    }
+
+    public static void run() throws IOException {
+        StringBuilder asm = new StringBuilder(".text\n");
+        for( boolean isArm : new boolean[]{false,true} )
+            for( boolean stack : new boolean[]{false,true} ) {
+                CodeGen code = new CodeGen("");
+                code._callingConv="SystemV";
+                code._mach=isArm ? new arm(code) : new x86_64_v2(code);
+                RegionNode block = new RegionNode(null,code._start,code._start);
+                code._cfg.add(block);
+                int flagsReg=isArm ? 64 : 32, firstStack=flagsReg+1;
+                RegMask flags = new RegMask(flagsReg);
+                Op def = new Op(flags,null,null,block);
+                RegMask killMask = stack ? (isArm ? new RegMask(0x7fffffffL,1L) : new RegMask(0x1ffffffefL)) : flags;
+                Op kill = new Op(null,null,killMask,block);
+                new Op(null,flags,null,block,def);
+                RegAlloc alloc = new RegAlloc(code);
+                alloc.regAlloc();
+
+                int splits=0, slots=0;
+                for( Node n : block._outputs ) if( n instanceof SplitNode split ) {
+                    int dst=alloc.regnum(n), src=alloc.regnum(n.in(1));
+                    assertTrue(split.outregmap().test(dst));
+                    assertTrue(split.regmap(1).test(src));
+                    for( int fp=isArm ? 32 : 16; fp<flagsReg; fp++ ) {
+                        assertFalse("FP output allowed",split.outregmap().test(fp));
+                        assertFalse("FP input allowed",split.regmap(1).test(fp));
+                    }
+                    if( dst>=firstStack || src>=firstStack ) slots++;
+                    splits++;
+                }
+                assertTrue(splits>=2);
+                assertEquals(stack,slots!=0);
+
+                // Keep the allocated registers, supplying a frame for encoding stack offsets.
+                FunNode frame = new FunNode(null,null,"flags",null,(Node)null);
+                code._regAlloc=new RegAlloc(code);
+                for( Node n : block._outputs )
+                    if( alloc.regnum(n)>=0 ) code._regAlloc.newLRG(n,frame)._reg=alloc.regnum(n);
+                Encoding save = new Encoding(code), restore = new Encoding(code);
+                Encoding enc = save;
+                for( Node n : block._outputs ) {
+                    if( n==kill ) enc=restore;
+                    if( n instanceof SplitNode split ) split.encoding(enc);
+                }
+                if( isArm ) {
+                    for( int bits=0; bits<16; bits++ ) {
+                        EvalArm64 cpu = new EvalArm64(new byte[1024],512);
+                        System.arraycopy(save._bits.buf(),0,cpu._buf,0,save._bits.size());
+                        System.arraycopy(restore._bits.buf(),0,cpu._buf,save._bits.size(),restore._bits.size());
+                        cpu.N=(bits&8)!=0; cpu.Z=(bits&4)!=0; cpu.C=(bits&2)!=0; cpu.V=(bits&1)!=0;
+                        assertEquals(0,cpu.step(save._bits.size()/4));
+                        cpu.N=cpu.Z=cpu.C=cpu.V=false;
+                        if( stack ) for( int r=0; r<31; r++ ) cpu.regs[r]=0;
+                        assertEquals(0,cpu.step(restore._bits.size()/4));
+                        assertEquals((bits&8)!=0,cpu.N); assertEquals((bits&4)!=0,cpu.Z);
+                        assertEquals((bits&2)!=0,cpu.C); assertEquals((bits&1)!=0,cpu.V);
+                        assertEquals(512,cpu.regs[31]);
+                    }
+                } else {
+                    Encoding body = new Encoding(code);
+                    int[] preserved={3,5,6,7,12,13,14,15};
+                    for( int r : preserved ) pushPop(body,r,false);
+                    X86.imm(body,0x81,5,4,16); // Reserve spill storage.
+                    X86.flags(body,TestC.OS.startsWith("Windows") ? 1 : 7,true);
+                    bytes(body,save);
+                    if( stack ) {
+                        for( int r=0; r<16; r++ ) if( r!=4 ) X86.constant(body,r,0);
+                    } else X86.reg(body,0x39,0,0); // CMP rax,rax clobbers only flags.
+                    bytes(body,restore);
+                    X86.flags(body,0,false); // Return the restored flags.
+                    X86.imm(body,0x81,0,4,16);
+                    for( int i=preserved.length-1; i>=0; i-- ) pushPop(body,preserved[i],true);
+                    X86.ret(body);
+                    String name=stack ? "flags_stack" : "flags_reg";
+                    asm.append(".globl ").append(name).append('\n').append(name).append(":\n.byte ");
+                    for( int i=0; i<body._bits.size(); i++ ) {
+                        if( i!=0 ) asm.append(',');
+                        asm.append(body._bits.buf()[i]&255);
+                    }
+                    asm.append('\n');
+                }
+            }
+        Path dir=Files.createTempDirectory(Path.of("build/objs"),"flag_spills_");
+        Files.writeString(dir.resolve("flags.s"),asm);
+        Files.writeString(dir.resolve("flags.c"),"""
+            typedef unsigned long long u64;
+            u64 __attribute__((CALL_CONV)) flags_reg(u64);
+            u64 __attribute__((CALL_CONV)) flags_stack(u64);
+            int main(void) {
+                const int positions[]={0,2,4,6,7,11};
+                for(int bits=0; bits<64; bits++) {
+                    u64 flags=0x202;
+                    for(int i=0;i<6;i++) if(bits&(1<<i)) flags|=1ULL<<positions[i];
+                    if((flags_reg(flags)&0x8d5)!=(flags&0x8d5)) return 1;
+                    if((flags_stack(flags)&0x8d5)!=(flags&0x8d5)) return 2;
+                }
+                return 0;
+            }
+            """);
+        String exe=dir.resolve(TestC.OS.startsWith("Windows") ? "flags.exe" : "flags").toString();
+        TestC.exec("gcc","-DCALL_CONV="+(TestC.OS.startsWith("Windows") ? "ms_abi" : "sysv_abi"),
+            "-o",exe,dir.resolve("flags.c").toString(),dir.resolve("flags.s").toString());
+        TestC.exec(exe);
+    }
+
+    private static void bytes(Encoding dst,Encoding src) {
+        for( int i=0; i<src._bits.size(); i++ ) dst.add1(src._bits.buf()[i]&255);
+    }
+    private static void pushPop(Encoding enc,int reg,boolean pop) {
+        if( reg>=8 ) enc.add1(0x41);
+        enc.add1((pop ? 0x58 : 0x50)+(reg&7));
+    }
+}
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/codegen/RegAllocTestSupport.java b/chapter25/src/test/java/com/seaofnodes/simple/codegen/RegAllocTestSupport.java
index 93380c87..292f1ae7 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/codegen/RegAllocTestSupport.java
+++ b/chapter25/src/test/java/com/seaofnodes/simple/codegen/RegAllocTestSupport.java
@@ -29,6 +29,12 @@ public class RegAllocTestSupport {
         return code;
     }
 
+    private static SplitNode testSplit(CodeGen code, MachNode def) {
+        LRG lrg = new LRG((short)0,null);
+        lrg._machDef = def;
+        return code._mach.split(lrg,"test",(byte)0);
+    }
+
     public static void uncoloredFixedNeighbor() throws Exception {
         CodeGen code = graph();
         RegAlloc alloc = new RegAlloc(code);
@@ -225,11 +231,11 @@ public class RegAllocTestSupport {
             RegAlloc alloc = new RegAlloc(code);
             Op def = new Op(A,null,null,false,code._start);
             alloc.newLRG(def,null)._reg=0;
-            SplitNode hi = code._mach.split(null,"test",(byte)0);
+            SplitNode hi = testSplit(code,def);
             hi.setDef(0,code._start); hi.setDef(1,def);
             alloc.newLRG(hi,null)._reg=1;
             new Op(null,null,killed ? A : null,false,code._start);
-            SplitNode lo = code._mach.split(null,"test",(byte)0);
+            SplitNode lo = testSplit(code,hi);
             lo.setDef(0,code._start); lo.setDef(1,hi);
             alloc.newLRG(lo,null)._reg=0;
             Op use = new Op(null,A,null,false,code._start,lo);
@@ -243,7 +249,7 @@ public class RegAllocTestSupport {
         uncolored.newLRG(def0,null)._mask=A;
         Op fixed = new Op(A,null,null,false,pre._start);
         uncolored.newLRG(fixed,null)._mask=A;
-        SplitNode copy = pre._mach.split(null,"test",(byte)0);
+        SplitNode copy = testSplit(pre,def0);
         copy.setDef(0,pre._start); copy.setDef(1,def0);
         assertFalse("A fixed definition clobbers even before coloring",uncolored.sameBlockNoClobber(copy));
     }
@@ -284,7 +290,7 @@ public class RegAllocTestSupport {
             RegAlloc alloc = new RegAlloc(code);
             Op def = new Op(A,null,null,false,code._start);
             alloc.newLRG(def,null)._reg=0;
-            SplitNode copy = code._mach.split(null,"test",(byte)0);
+            SplitNode copy = testSplit(code,def);
             copy.setDef(0,code._start); copy.setDef(1,def);
             alloc.newLRG(copy,null)._reg=1;
             if( kind==3 ) new Op(null,null,A,false,code._start);
@@ -307,7 +313,7 @@ public class RegAllocTestSupport {
             CodeGen code = graph();
             RegAlloc alloc = new RegAlloc(code);
             Op def = new Op(new RegMask(3L),null,null,false,code._start);
-            SplitNode copy = code._mach.split(null,"test",(byte)0);
+            SplitNode copy = testSplit(code,def);
             copy.setDef(0,code._start); copy.setDef(1,def);
             Op use = new Op(null,new RegMask(3L),null,false,code._start,copy);
             LRG from = alloc.newLRG(def,null), to = alloc.newLRG(copy,null);