Finalize function semantics

Rename ScopeMin to MergeMem.
Move Var to its own file.
Allow out-of-scope id lookups in functions, as long as its a final constant.
This allows e.g. factorial to find "fact" as an out-of-scope final constant function.

3 files changed, 84 insertions, 57 deletions

diff --git a/chapter18/src/test/java/com/seaofnodes/simple/Chapter18Test.java b/chapter18/src/test/java/com/seaofnodes/simple/Chapter18Test.java
index 39da0c72..75ad301e 100644
--- a/chapter18/src/test/java/com/seaofnodes/simple/Chapter18Test.java
+++ b/chapter18/src/test/java/com/seaofnodes/simple/Chapter18Test.java
@@ -1,26 +1,27 @@
 package com.seaofnodes.simple;
 
-import com.seaofnodes.simple.evaluator.Evaluator;
 import org.junit.Test;
-import org.junit.Ignore;
-
 import static org.junit.Assert.*;
+import static org.junit.Assert.fail;
+import org.junit.Ignore;
 
 public class Chapter18Test {
 
     @Test
     public void testJig() {
-        CodeGen code = new CodeGen("""
+        CodeGen code = new CodeGen(
+"""
 return 0;
 """);
-        code.parse(true).opto().typeCheck().GCM();
+        code.parse(false).opto().typeCheck().GCM();
         assertEquals("return 0;", code._stop.toString());
         assertEquals("0", Eval2.eval(code,  0));
     }
 
     @Test
     public void testPhiParalleAssign() {
-        CodeGen code = new CodeGen("""
+        CodeGen code = new CodeGen(
+"""
 int a = 1;
 int b = 2;
 while(arg--) {
@@ -42,7 +43,8 @@ return a;
     // ---------------------------------------------------------------
     @Test
     public void testType0() {
-        CodeGen code = new CodeGen("""
+        CodeGen code = new CodeGen(
+"""
 {int -> int}? x2 = null; // null function ptr
 return x2;
 """);
@@ -53,7 +55,8 @@ return x2;
 
     @Test
     public void testFcn0() {
-        CodeGen code = new CodeGen("""
+        CodeGen code = new CodeGen(
+"""
 {int -> int}? sq = { int x ->
     x*x;
 };
@@ -66,7 +69,8 @@ return sq;
 
     @Test
     public void testFcn1() {
-        CodeGen code = new CodeGen("""
+        CodeGen code = new CodeGen(
+"""
 var sq = { int x ->
     x*x;
 };
@@ -77,9 +81,48 @@ return sq(arg)+sq(3);
         assertEquals("13", Eval2.eval(code, 2));
     }
 
-    // Recursive factorial test
+    // Function scope test
     @Test
     public void testFcn2() {
+        CodeGen code = new CodeGen(
+"""
+int cnt=1;
+return { -> cnt; };
+""");
+        try { code.parse().opto(); fail(); }
+        catch( Exception e ) { assertEquals("Variable 'cnt' is out of function scope and must be a final constant",e.getMessage()); }
+    }
+
+    // Function scope test
+    @Test
+    public void testFcn3() {
+        CodeGen code = new CodeGen(
+"""
+val cnt=2;
+return { -> cnt; }();
+""");
+        code.parse().opto();
+        assertEquals("return 2;", code._stop.toString());
+        assertEquals("2", Eval2.eval(code, 0));
+    }
+
+    // Function variables
+    @Test
+    public void testFcn4() {
+        CodeGen code = new CodeGen(
+"""
+var fcn = arg ? { int x -> x*x; } : { int x -> x+x; };
+return fcn(3);
+""");
+        code.parse().opto();
+        assertEquals("Stop[ return Phi(Region,{ int -> int #1},{ int -> int #2})( 3); return (Parm_x(null,int)*x); return (Parm_x(null,int)*2); ]", code._stop.toString());
+        assertEquals("6", Eval2.eval(code, 0));
+        assertEquals("9", Eval2.eval(code, 1));
+    }
+
+    // Recursive factorial test
+    @Test
+    public void testFcn5() {
         CodeGen code = new CodeGen("val fact = { int x -> x <= 1 ? 1 : x*fact(x-1); }; return fact(arg);");
         code.parse().opto();
         assertEquals("Stop[ return fact( arg); return Phi(Region,1,(Parm_x(fact,int,arg,(x-1))*fact( Sub))); ]", code._stop.toString());
@@ -90,34 +133,21 @@ return sq(arg)+sq(3);
         assertEquals("24", Eval2.eval(code, 4));
     }
 
-
-
+    // Mutual recursion.  Fails without SCCP to lift the recursive return types.
     @Ignore @Test
-    public void testFcn3() {
+    public void testFcn6() {
         CodeGen code = new CodeGen(
 """
-val counter = { ->
-    int cnt;
-    val rez = new {int}?[2];
-    rez[0] = { ->   cnt; };
-    rez[1] = { -> ++cnt; };
-    return rez;
-};
-val A = counter();
-val B = counter();
-int[] rez = new int[5];
-rez[0] = A[0](); // Value of counter A
-rez[1] = A[1](); // Increment counter A
-rez[2] = B[0](); // Value of counter B
-B[1]();          // Increment B
-B[1]();          // Increment B
-rez[3] = B[0](); // Value of counter B
-rez[4] = A[0]() * 10 + B[0]();
-return rez;
+val is_even = { int x -> x ? is_odd (x-1) : true ; };
+val is_odd  = { int x -> x ? is_even(x-1) : false; };
+return is_even(arg);
 """);
         code.parse().opto();
-        assertEquals("Stop[ return (const)[int]; return (const)[{ -> int #ALL}?]; return 0; return 1; ]", code._stop.toString());
-        assertEquals("13", Eval2.eval(code, 0));
+        assertEquals("Stop[ return is_even( arg); return Phi(Region,Phi(Region,is_even( ((Parm_x(is_even,int,arg,Sub)-1)-1)),0),1); ]", code._stop.toString());
+        assertEquals("1", Eval2.eval(code, 0));
+        assertEquals("0", Eval2.eval(code, 1));
+        assertEquals("1", Eval2.eval(code, 2));
+        assertEquals("0", Eval2.eval(code, 3));
     }
 
 }
diff --git a/chapter18/src/test/java/com/seaofnodes/simple/Eval2.java b/chapter18/src/test/java/com/seaofnodes/simple/Eval2.java
index 757699e4..66b5c28b 100644
--- a/chapter18/src/test/java/com/seaofnodes/simple/Eval2.java
+++ b/chapter18/src/test/java/com/seaofnodes/simple/Eval2.java
@@ -132,18 +132,9 @@ public abstract class Eval2 {
         // Return from main hits Stop
         F.put(BB,new Closure(code._stop,F));
 
-        // Set incoming arg into main
-        FunNode main = (FunNode)code._start.uctrl();
-        assert main.sig().isa(TypeFunPtr.MAIN);
-        for( Node use : main._outputs )
-            if( use instanceof ParmNode parm && parm._idx==2 ) {
-                parm.setDef(1,new ConstantNode( TypeInteger.constant( arg ) ).init() );
-                F.put( parm.in(1), arg );
-            }
-
 
         // ------------
-        // Evaluate until we exit or timeout.  Each outer loop step computes
+        // Evaluate until exit or timeout.  Each outer loop step computes
         // all data nodes under some new Control.
         while( true ) {
             traceCtrl(BB,trace);
@@ -184,19 +175,26 @@ public abstract class Eval2 {
 
         // Compute input path on Phis for this Region
         int path = r._inputs.find( prior );
+        // Parameters read from prior frame, Phis from local frame
+        Frame frame = (r instanceof FunNode ? F._prior : F);
+        boolean isMain = r instanceof FunNode fun && fun.sig().isa(TypeFunPtr.MAIN);
 
         // Parallel assign Phis.  First parallel read and cache
         int i;
-        for( i = 0; i < r.nOuts(); i++ )
-            if( r.out(i) instanceof PhiNode phi )
-                // Parameters read from prior frame, Phis from local frame
-                PHICACHE[i] = (r instanceof FunNode ? F._prior : F)
-                    .get( (phi instanceof ParmNode parm && parm._idx==0)
-                          // RPC reads the Call directly
-                          ? phi.region().in(path)
-                          // Phis read from path input
-                          : phi.in(path));
-            else break;
+        for( i = 0; i < r.nOuts(); i++ ) {
+            if( !(r.out(i) instanceof PhiNode phi) ) break;
+            if( isMain && phi instanceof ParmNode parm && parm._idx==2 )
+                PHICACHE[i] = arg; // Reading the initial arguments to main()
+            else {
+                Node n = phi instanceof ParmNode parm
+                    // RPC reads the Call directly;
+                    // Parms may not be linked, so read call args directly
+                    ? (parm._idx==0 ? prior : prior.in(parm._idx))
+                    // Phis read from path input
+                    :  phi.in(path);
+                PHICACHE[i] = frame.get(n);
+            }
+        }
         // Parallel assign; might assign before read, so read from cache
         for( int j=0; j < i; j++ )
             traceData(F.put0(r.out(j),PHICACHE[j]),trace);
@@ -204,6 +202,7 @@ public abstract class Eval2 {
         return i;
     }
 
+
     // Make a call.
     private static CFGNode call( CallNode call ) {
         // Set up the Return PC and return frame (which is just the current frame).
@@ -271,7 +270,7 @@ public abstract class Eval2 {
         case ProjNode     proj -> proj._type instanceof TypeMem ? "$mem" : val(proj.in(0));
         case ReadOnlyNode read -> val(read.in(1));
         case SarNode      sar  -> x(sar.in(1)) >> x(sar.in(2));
-        case ScopeMinNode merge-> "$mem";
+        case MemMergeNode merge-> "$mem";
         case ShlNode      shl  -> x(shl.in(1)) << x(shl.in(2));
         case ShrNode      shr  -> x(shr.in(1)) >>>x(shr.in(2));
         case StoreNode    st   -> store(st);
diff --git a/chapter18/src/test/java/com/seaofnodes/simple/evaluator/Evaluator.java b/chapter18/src/test/java/com/seaofnodes/simple/evaluator/Evaluator.java
index 8e25b133..92b424df 100644
--- a/chapter18/src/test/java/com/seaofnodes/simple/evaluator/Evaluator.java
+++ b/chapter18/src/test/java/com/seaofnodes/simple/evaluator/Evaluator.java
@@ -4,8 +4,6 @@ import com.seaofnodes.simple.Utils;
 import com.seaofnodes.simple.node.*;
 import com.seaofnodes.simple.type.*;
 
-import java.lang.invoke.MethodHandle;
-import java.lang.invoke.MethodHandles;
 import java.util.*;
 
 public class Evaluator {
@@ -307,7 +305,7 @@ public class Evaluator {
             case NewNode      alloc -> alloc(alloc);
             case CProjNode    cproj -> ((Object[])val(cproj.ctrl()))[cproj._idx];
             case ProjNode     proj  -> ((Object[])val( proj.in(0) ))[ proj._idx];
-            case ScopeMinNode mem   -> null;
+            case MemMergeNode mem   -> null;
             case ReadOnlyNode ro    -> val(ro.in(1));
             case CallNode     call  -> Utils.TODO(); // should not reach here, go the IfNode route
             default                 -> throw new AssertionError("Unexpected node " + node);