Change field mutability

Fields & locals with an initializer are immutable by default; those without are mutable.  Make mutable with `!`.  Fields are always mutable in a constructor.
Add a trinary `pred ? then : else` syntax.
SubNode retains as much precision as AddNode.
Sharpen some asserts and error cases.
Limit Load node cloning if the ptr is not obvious.

6 files changed, 148 insertions, 21 deletions

diff --git a/chapter17/src/test/java/com/seaofnodes/simple/BrainFuckTest.java b/chapter17/src/test/java/com/seaofnodes/simple/BrainFuckTest.java
index abb8b834..de6852c7 100644
--- a/chapter17/src/test/java/com/seaofnodes/simple/BrainFuckTest.java
+++ b/chapter17/src/test/java/com/seaofnodes/simple/BrainFuckTest.java
@@ -24,7 +24,7 @@ public class BrainFuckTest {
         Parser parser = new Parser(
                 encoded + """
 var pc = 0, d = 0;
-u8[] output = new u8[0];
+u8[] !output = new u8[0];
 val data = new u8[100];
 
 while (pc < program#) {
diff --git a/chapter17/src/test/java/com/seaofnodes/simple/Chapter03Test.java b/chapter17/src/test/java/com/seaofnodes/simple/Chapter03Test.java
index c76df903..4525918c 100644
--- a/chapter17/src/test/java/com/seaofnodes/simple/Chapter03Test.java
+++ b/chapter17/src/test/java/com/seaofnodes/simple/Chapter03Test.java
@@ -31,7 +31,7 @@ public class Chapter03Test {
 
     @Test
     public void testVarScopeNoPeephole() {
-        Parser parser = new Parser("int a=1; int b=2; int c=0; { int b=3; c=a+b;  } return c; ");
+        Parser parser = new Parser("int a=1; int b=2; int !c=0; { int b=3; c=a+b;  } return c; ");
         Node._disablePeephole = true;
         StopNode ret = parser.parse();
         Node._disablePeephole = false;
@@ -58,7 +58,7 @@ public class Chapter03Test {
     @Test
     public void testBad1() {
         try {
-            new Parser("int a=1; int b=2; int c=0; { int b=3; c=a+b;").parse();
+            new Parser("int a=1; int b=2; int !c=0; { int b=3; c=a+b;").parse();
             fail();
         } catch( RuntimeException e ) {
             assertEquals("Syntax error, expected }: ",e.getMessage());
diff --git a/chapter17/src/test/java/com/seaofnodes/simple/Chapter04Test.java b/chapter17/src/test/java/com/seaofnodes/simple/Chapter04Test.java
index 70f38dd6..24612fee 100644
--- a/chapter17/src/test/java/com/seaofnodes/simple/Chapter04Test.java
+++ b/chapter17/src/test/java/com/seaofnodes/simple/Chapter04Test.java
@@ -96,14 +96,14 @@ public class Chapter04Test {
 
     @Test
     public void testBug1() {
-        Parser parser = new Parser("int a=arg+1; int b=a; b=1; return a+2; ");
+        Parser parser = new Parser("int a=arg+1; int !b=a; b=1; return a+2; ");
         StopNode ret = parser.parse();
         assertEquals("return (arg+3);", ret.print());
     }
 
     @Test
     public void testBug2() {
-        Parser parser = new Parser("int a=arg+1; a=a; return a; ");
+        Parser parser = new Parser("int !a=arg+1; a=a; return a; ");
         StopNode ret = parser.parse();
         assertEquals("return (arg+1);", ret.print());
     }
diff --git a/chapter17/src/test/java/com/seaofnodes/simple/Chapter13Test.java b/chapter17/src/test/java/com/seaofnodes/simple/Chapter13Test.java
index 165d23e5..aa659147 100644
--- a/chapter17/src/test/java/com/seaofnodes/simple/Chapter13Test.java
+++ b/chapter17/src/test/java/com/seaofnodes/simple/Chapter13Test.java
@@ -144,7 +144,7 @@ struct S{};
     public void testForwardRef0() {
         Parser parser = new Parser(
 """
-struct S1 { S2 s; };
+struct S1 { S2? s; };
 return new S2;
 """);
         try { parser.parse().iterate(); fail(); }
diff --git a/chapter17/src/test/java/com/seaofnodes/simple/Chapter16Test.java b/chapter17/src/test/java/com/seaofnodes/simple/Chapter16Test.java
index ad287e82..be48ec55 100644
--- a/chapter17/src/test/java/com/seaofnodes/simple/Chapter16Test.java
+++ b/chapter17/src/test/java/com/seaofnodes/simple/Chapter16Test.java
@@ -43,23 +43,23 @@ return x+y;
         assertEquals(5L, Evaluator.evaluate(stop,  0));
     }
 
-    @Test
-    public void testFinal0() {
-        Parser parser = new Parser(
-"""
-int !x=2;
-x=3;
-return x;
-""");
-        try { parser.parse().iterate(); fail(); }
-        catch( Exception e ) { assertEquals("Cannot reassign final 'x'",e.getMessage()); }
-    }
+//    @Test
+//    public void testFinal0() {
+//        Parser parser = new Parser(
+//"""
+//int !x=2;
+//x=3;
+//return x;
+//""");
+//        try { parser.parse().iterate(); fail(); }
+//        catch( Exception e ) { assertEquals("Cannot reassign final 'x'",e.getMessage()); }
+//    }
 
     @Test
     public void testFinal1() {
         Parser parser = new Parser(
 """
-int !x=2, y=3;
+int x=2, y=3;
 if( arg ) { int x = y; x = x*x; y=x; } // Shadow final x
 return y;
 """);
@@ -107,7 +107,7 @@ return z.x;
 
 
     @Test
-    public void testStructFinal() {
+    public void testStructFinal0() {
         Parser parser = new Parser("""
 struct Point { int !x, !y; };
 Point p = new Point { x=3; y=4; };
@@ -118,6 +118,67 @@ return p;
         assertEquals("Obj<Point>{x=3,y=4}", Evaluator.evaluate(stop,  0).toString());
     }
 
+    @Test
+    public void testStructFinal1() {
+        Parser parser = new Parser("""
+struct Point { int x=3, y=4; };
+Point p = new Point { x=5; y=6; };
+p.x++;
+return p;
+""");
+        try { parser.parse().iterate(); fail(); }
+        catch( Exception e ) { assertEquals("Cannot reassign final 'x'",e.getMessage()); }
+    }
+
+    @Test
+    public void testStructFinal2() {
+        Parser parser = new Parser("""
+struct Point { int x=3, y=4; };
+Point p = new Point;
+p.x++;
+return p;
+""");
+        try { parser.parse().iterate(); fail(); }
+        catch( Exception e ) { assertEquals("Cannot reassign final 'x'",e.getMessage()); }
+    }
+
+    @Test
+    public void testStructFinal3() {
+        Parser parser = new Parser("""
+struct Point { var x; var y; };
+Point p = new Point;
+p.x++;
+return p;
+""");
+        try { parser.parse().iterate(); fail(); }
+        catch( Exception e ) { assertEquals("Syntax error, expected expression: ;",e.getMessage()); }
+    }
+
+    @Test
+    public void testStructFinal4() {
+        Parser parser = new Parser("""
+struct Point { val x=3; val y=4; };
+Point p = new Point;
+p.x++;
+return p;
+""");
+        try { parser.parse().iterate(); fail(); }
+        catch( Exception e ) { assertEquals("Cannot reassign final 'x'",e.getMessage()); }
+    }
+
+    @Test
+    public void testStructFinal5() {
+        Parser parser = new Parser("""
+struct Point { var x=3; var y=4; };
+Point p = new Point;
+p.x++;
+return p;
+""");
+        StopNode stop = parser.parse().iterate();
+        assertEquals("return Point;", stop.toString());
+        assertEquals("Obj<Point>{x=4,y=4}", Evaluator.evaluate(stop,  0).toString());
+    }
+
     // Same as the Chapter13 test with the same name, but using the new
     // constructor syntax
     @Test
@@ -152,7 +213,7 @@ while( arg ) {
     head = new LLI {
         next=head;
         // Any old code in the constructor
-        int tmp=arg;
+        int !tmp=arg;
         while( arg > 10 ) {
             tmp = tmp + arg;
             arg = arg - 1;
@@ -182,7 +243,7 @@ struct Square {
     // Newtons approximation to the square root, computed in a constructor.
     // The actual allocation will copy in this result as the initial
     // value for 'diag'.
-    flt diag = arg*arg/2;
+    flt !diag = arg*arg/2;
     while( 1 ) {
         flt next = (side/diag + diag)/2;
         if( next == diag ) break;
diff --git a/chapter17/src/test/java/com/seaofnodes/simple/Chapter17Test.java b/chapter17/src/test/java/com/seaofnodes/simple/Chapter17Test.java
index 96f12480..5db9592e 100644
--- a/chapter17/src/test/java/com/seaofnodes/simple/Chapter17Test.java
+++ b/chapter17/src/test/java/com/seaofnodes/simple/Chapter17Test.java
@@ -2,6 +2,7 @@ package com.seaofnodes.simple;
 
 import com.seaofnodes.simple.evaluator.Evaluator;
 import com.seaofnodes.simple.node.StopNode;
+import org.junit.Ignore;
 import org.junit.Test;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.fail;
@@ -97,6 +98,71 @@ return d;
         catch( Exception e ) { assertEquals("Syntax error, expected expression: ;",e.getMessage()); }
     }
 
+
+    @Test
+    public void testTrinary0() {
+        Parser parser = new Parser("""
+return arg ? 1 : 2;
+""");
+        StopNode stop = parser.parse().iterate();
+        assertEquals("return Phi(Region19,1,2);", stop.toString());
+        assertEquals(2L, Evaluator.evaluate(stop, 0));
+        assertEquals(1L, Evaluator.evaluate(stop, 1));
+    }
+
+    @Test
+    public void testTrinary1() {
+        Parser parser = new Parser("""
+return arg ? 0 : arg;
+""");
+        StopNode stop = parser.parse().iterate();
+        assertEquals("return 0;", stop.toString());
+        assertEquals(0L, Evaluator.evaluate(stop, 0));
+    }
+
+    @Test
+    public void testTrinary2() {
+        Parser parser = new Parser("""
+struct Bar { int x; };
+var b = arg ? new Bar : null;
+return b ? b.x++ + b.x++ : -1;
+""");
+        StopNode stop = parser.parse().iterate();
+        assertEquals("return Phi(Region54,1,-1);", stop.toString());
+        assertEquals(-1L, Evaluator.evaluate(stop, 0));
+        assertEquals( 1L, Evaluator.evaluate(stop, 1));
+    }
+
+    @Test
+    public void testTrinary3() {
+        Parser parser = new Parser("""
+struct Bar { int x; };
+var b = arg ? new Bar;
+return b ? b.x++ + b.x++ : -1;
+""");
+        StopNode stop = parser.parse().iterate();
+        assertEquals("return Phi(Region54,1,-1);", stop.toString());
+        assertEquals(-1L, Evaluator.evaluate(stop, 0));
+        assertEquals( 1L, Evaluator.evaluate(stop, 1));
+    }
+
+    @Ignore
+    @Test
+    public void testTrinary4() {
+        Parser parser = new Parser("""
+struct Bar { Bar? next; int x; };
+var b = arg ? new Bar { next = (arg==2) ? new Bar{x=2;}; x=1; };
+return b ? b.next ? b.next.x : b.x; // parses "b ? (b.next ? b.next.x : b.x) : 0"
+""");
+        StopNode stop = parser.parse().iterate();
+        assertEquals("return Phi(Region51,1,-1);", stop.toString());
+        assertEquals( 0L, Evaluator.evaluate(stop, 0));
+        assertEquals( 1L, Evaluator.evaluate(stop, 1));
+        assertEquals( 2L, Evaluator.evaluate(stop, 2));
+    }
+
+
+
     @Test
     public void testLinkedList2() {
         Parser parser = new Parser("""