Remove a bunch of extra graph walks pre-Optoescape-flowch29-cleanup

Removed most; moved a few into Opto setup pass.
Lots of modest bug fixes

11 files changed, 174 insertions, 32 deletions

diff --git a/chapter29/src/test/java/com/seaofnodes/simple/ArithNodeTest.java b/chapter29/src/test/java/com/seaofnodes/simple/ArithNodeTest.java
index b28a6af3..1e6c6fc0 100644
--- a/chapter29/src/test/java/com/seaofnodes/simple/ArithNodeTest.java
+++ b/chapter29/src/test/java/com/seaofnodes/simple/ArithNodeTest.java
@@ -15,7 +15,8 @@ public class ArithNodeTest {
         Node zero = ConstantNode.seed(TypeInteger.ZERO);
         for( Node op : new Node[]{new MulNode(x,zero,(byte)1),new AndNode(null,x,zero),
                 new SubNode(x,x,(byte)1),new BoolNode.EQ(x,x,(byte)1),
-                new BoolNode.NE(x,x,(byte)1),new BoolNode.ULT(x,x),new NotNode(x)} ) {
+                new BoolNode.NE(x,x,(byte)1),new BoolNode.ULT(x,x),new NotNode(x),
+                new ConvertNode(TypeInteger.BOT,x),new ToIntegerNode(x),new ToFloatNode(x),new PtrToIntNode(x)} ) {
             assertSame(op.label(),TypeScalar.BOT,op.compute());
             Node replacement = op.idealize();
             assertTrue(op.label(),replacement==null || !replacement.compute().isConstant());
diff --git a/chapter29/src/test/java/com/seaofnodes/simple/CallEndTest.java b/chapter29/src/test/java/com/seaofnodes/simple/CallEndTest.java
index a174bdf7..f57fd96a 100644
--- a/chapter29/src/test/java/com/seaofnodes/simple/CallEndTest.java
+++ b/chapter29/src/test/java/com/seaofnodes/simple/CallEndTest.java
@@ -7,6 +7,60 @@ import org.junit.Test;
 import static org.junit.Assert.*;
 
 public class CallEndTest {
+    // An unknown value can become a private object or callback. Both escape
+    // sinks must reserve those possibilities before the value is known.
+    @Test public void testUnknownEscapesRefineToPrivateValues() {
+        CodeGen code = new CodeGen("return 0;").parse();
+        code._phase = CodeGen.Phase.IterPostOpto;
+        StopCUNode stop = code.compunit()._stop;
+        stop._type = TypeTuple.make(Type.CONTROL,TypeMem.START,Type.BOTTOM);
+        ReturnNode ret = (ReturnNode)stop.in(0);
+        TypeFunPtr callback = TypeFunPtr.make1((byte)2,true,TypeFunPtr.TEMPTY,TypeInteger.BOT,100);
+        TypeMemPtr object = TypeMemPtr.make(TypeStruct.make("_Private",false,
+            Field.make("callback",callback,100,false)));
+        code.externFunc(101,"retain");
+        TypeFunPtr retain = TypeFunPtr.make1((byte)2,true,
+            new Type[]{TypeScalar.BOT},TypeInteger.BOT,101);
+        Node value = ConstantNode.raw(TypeScalar.BOT);
+        CallNode call = new CallNode(null,ConstantNode.raw(Type.CONTROL),
+            ConstantNode.raw(TypeMem.START),value,ConstantNode.raw(retain));
+        call._type = Type.CONTROL;
+        GlobalEscapeNode global = new GlobalEscapeNode();
+        global._type = TypeMem.START;
+        for( Type broad : new Type[]{Type.BOTTOM,TypeScalar.BOT} ) {
+            value._type = broad;
+            ret._type = TypeTuple.make(Type.CONTROL,TypeMem.START,broad);
+            TypeTuple unknownStop = stop.compute();
+            TypeMem unknownGlobal = global.compute();
+            assertSame(XInt.FULL,((TypeMem)unknownStop.mem())._escFs);
+            assertSame(XInt.FULL,((TypeMem)unknownStop.mem())._escAs);
+            assertSame(XInt.FULL,unknownGlobal._escFs);
+            assertSame(XInt.FULL,unknownGlobal._escAs);
+            for( Type precise : new Type[]{object,callback} ) {
+                assertTrue(precise.isa(broad));
+                value._type = precise;
+                ret._type = TypeTuple.make(Type.CONTROL,TypeMem.START,precise);
+                assertTrue(stop.compute().isa(unknownStop));
+                assertTrue(global.compute().isa(unknownGlobal));
+            }
+        }
+    }
+
+    @Test public void testUnresolvedOffsetInInlineBody() {
+        CodeGen code = new CodeGen("val f = { int[] data -> return data#; }; return f;").parse();
+        for( FunNode fun : code._linker )
+            if( fun!=null && "f".equals(fun._name) ) {
+                // Keep the offset unresolved: an early inline must copy it
+                // with its data parameter, not share it with the old body.
+                FldOffNode off = new FldOffNode(fun.parm(3),"<<",null).init();
+                fun.ret().setDef(2,off);
+                assertSame(Type.BOTTOM,off._type);
+                assertTrue("Unresolved field offset belongs to the function",fun.body().get(off._nid));
+                return;
+            }
+        fail("Missing test function");
+    }
+
     @Test public void testReturnWideningMonotonicity() {
         new CodeGen("return 0;").parse();
         TypeFunPtr sig = TypeFunPtr.make1((byte)2,true,TypeFunPtr.TEMPTY,TypeInteger.I32,100);
diff --git a/chapter29/src/test/java/com/seaofnodes/simple/Chapter10Test.java b/chapter29/src/test/java/com/seaofnodes/simple/Chapter10Test.java
index 1a954110..eadaf9fe 100644
--- a/chapter29/src/test/java/com/seaofnodes/simple/Chapter10Test.java
+++ b/chapter29/src/test/java/com/seaofnodes/simple/Chapter10Test.java
@@ -158,7 +158,7 @@ else
 return v;
 """);
         code.driver(CodeGen.Phase.FinalizeIR);
-        assertEquals("Stop[ return Test.Vector2D; return MemTop; return Test.Vector2D; ]", code.print());
+        assertEquals("Stop[ return Test.Vector2D; return Test.Vector2D; ]", code.print());
     }
 
     @Test
@@ -196,7 +196,7 @@ while (arg) {
 return bar.a;
 """);
         code.driver(CodeGen.Phase.FinalizeIR);
-        assertEquals("Stop[ return Phi(Loop,0,(Phi_a+2)); return MemTop; return Test.Bar; ]", code.print());
+        assertEquals("Stop[ return Phi(Loop,0,(Phi_a+2)); return Test.Bar; ]", code.print());
     }
 
     @Test
@@ -245,10 +245,10 @@ struct _Bar { int a; };
 !_Bar? !bar = new _Bar;
 if (arg) bar = null;
 if( bar ) bar.a = 1;
-return bar.a;
+return bar;
 """);
-        code.driver(CodeGen.Phase.FinalizeIR);
-        assertEquals("return Phi(Region,1,.a);", code.print());
+        code.driver(CodeGen.Phase.TypeCheck);
+        assertEquals("return Phi(Region,null,Test._Bar);", code.print());
     }
 
     @Test
@@ -318,7 +318,7 @@ while( i.x < i.len ) {
 return sum;
 """);
         code.driver(CodeGen.Phase.FinalizeIR);
-        assertEquals("Stop[ return Phi(Loop,0,(Phi(Loop,0,(Phi_x+1))+Phi_sum)); return MemTop; return Test.Iter; ]", code.print());
+        assertEquals("Stop[ return Phi(Loop,0,(Phi(Loop,0,(Phi_x+1))+Phi_sum)); return Test.Iter; ]", code.print());
     }
 
 
@@ -337,7 +337,7 @@ while(arg) {
 return ret;
 """);
         code.driver(CodeGen.Phase.FinalizeIR);
-        assertEquals("Stop[ return Phi(Loop,Test.s0,Phi(Region,Test.s0,Phi_ret)); return MemTop; return Test.s0; ]", code.print());
+        assertEquals("Stop[ return Phi(Loop,Test.s0,Phi(Region,Test.s0,Phi_ret)); return Test.s0; ]", code.print());
     }
 
     @Test
@@ -390,7 +390,7 @@ s0 b = new s0();
 return a.x * 100 + b.x * 10 + cnt;
 """);
         code.driver(CodeGen.Phase.FinalizeIR);
-        assertEquals("Stop[ return 112; return MemTop; return Test.s0; ]", code.print());
+        assertEquals("Stop[ return 112; return Test.s0; ]", code.print());
     }
 
 
@@ -433,7 +433,7 @@ else return new s0;
 if(new s0.f0) return 0;
     """);
         code.driver(CodeGen.Phase.TypeCheck);
-        assertEquals("Stop[ return Test.s0; return MemTop; return Test.s0; ]", code.print());
+        assertEquals("Stop[ return Test.s0; return Test.s0; ]", code.print());
     }
 
     @Test
@@ -461,7 +461,7 @@ s0 v1 = v0;
 return v1;
     """);
         code.driver(CodeGen.Phase.FinalizeIR);
-        assertEquals("Stop[ return (const)Test.s0; return MemTop; return Test.s0; ]", code.print());
+        assertEquals("Stop[ return (const)Test.s0; return Test.s0; ]", code.print());
     }
 
 
diff --git a/chapter29/src/test/java/com/seaofnodes/simple/Chapter12Test.java b/chapter29/src/test/java/com/seaofnodes/simple/Chapter12Test.java
index 156e091d..c6817308 100644
--- a/chapter29/src/test/java/com/seaofnodes/simple/Chapter12Test.java
+++ b/chapter29/src/test/java/com/seaofnodes/simple/Chapter12Test.java
@@ -79,6 +79,19 @@ return f0.i.f.i.i;
         assertEquals("return 17;", code.print());
     }
 
+    @Test public void testPrivateRecursiveReturn() {
+        CodeGen code = new CodeGen("""
+            struct _A { !Test._B? !b; };
+            struct _B { !_A? !a; };
+            !_A !_a = new _A;
+            !_B !_b = new _B;
+            _a.b = _b;
+            _b.a = _a;
+            return _a.b.a.b;
+            """).driver(CodeGen.Phase.TypeCheck);
+        assertEquals("return Test._B;",code.print());
+    }
+
     @Test
     public void testNullRef0() {
         CodeGen code = new CodeGen(
@@ -101,7 +114,7 @@ N n = new N(new M);
 return n.next;
 """);
         code.driver(CodeGen.Phase.FinalizeIR);
-        assertEquals("Stop[ return (const)Test.M; return MemTop; return Test.M; return MemTop; return MemTop; return Test.N; ]", code.print());
+        assertEquals("Stop[ return (const)Test.M; return Test.M; return Test.N; ]", code.print());
     }
 
     @Test
diff --git a/chapter29/src/test/java/com/seaofnodes/simple/Chapter17bTest.java b/chapter29/src/test/java/com/seaofnodes/simple/Chapter17bTest.java
index 1e99bcd9..98197b77 100644
--- a/chapter29/src/test/java/com/seaofnodes/simple/Chapter17bTest.java
+++ b/chapter29/src/test/java/com/seaofnodes/simple/Chapter17bTest.java
@@ -293,7 +293,9 @@ struct A { !B !b; new A = { ->
 A x = new A;
 """);
         try { code.driver(CodeGen.Phase.TypeCheck); fail(); }
-        catch( Exception e ) { assertEquals("Field 'b' might not be initialized",e.getMessage()); }
+        // The unused constructor return value can die; its unwritten field
+        // still fails the completion check at TypeCheck.
+        catch( Exception e ) { assertEquals("'Test.A' is not fully initialized, field 'b' is only partially set in the constructor",e.getMessage()); }
     }
 
     @Test
@@ -305,7 +307,7 @@ A x = new A;
             "new A = { -> }; !B !b;",              // Field declared later
         } ) {
             CodeGen code = new CodeGen("struct B {}; struct A { "+fields+" }; return 0;");
-            try { code.parse(); fail(fields); }
+            try { code.driver(CodeGen.Phase.TypeCheck); fail(fields); }
             catch( Parser.ParseException e ) { assertEquals("'Test.A' is not fully initialized, field 'b' is only partially set in the constructor",e.getMessage()); }
         }
     }
@@ -314,7 +316,7 @@ A x = new A;
     public void testDefaultConstructorFields() {
         for( String field : new String[] { "!B !b;", "!B !b;" } ) {
             CodeGen code = new CodeGen("struct B {}; struct A { "+field+" }; return new A;");
-            try { code.parse(); fail(field); }
+            try { code.driver(CodeGen.Phase.TypeCheck); fail(field); }
             catch( Parser.ParseException e ) { assertEquals("'Test.A' is not fully initialized, field 'b' needs to be set in a constructor",e.getMessage()); }
         }
         for( String fields : new String[] {
@@ -550,7 +552,7 @@ struct _A {
 };
 return new _A;
 """);
-        code.driver(CodeGen.Phase.FinalizeIR);
+        code.driver(CodeGen.Phase.TypeCheck);
         assertEquals("return Test._A;", code.print());
         assertEquals("Test._A{f1=null,f2=null}", Eval2.eval(code,0));
     }
@@ -565,7 +567,7 @@ struct _A {
 };
 return new _A(new !B?[0]).array_of_b;
 """);
-        code.driver(CodeGen.Phase.FinalizeIR);
+        code.driver(CodeGen.Phase.TypeCheck);
         assertEquals("return []*B?;", code.print());
         assertEquals("*B {}?[]", Eval2.eval(code,0));
     }
diff --git a/chapter29/src/test/java/com/seaofnodes/simple/Chapter19Test.java b/chapter29/src/test/java/com/seaofnodes/simple/Chapter19Test.java
index e6249d82..50ca8922 100644
--- a/chapter29/src/test/java/com/seaofnodes/simple/Chapter19Test.java
+++ b/chapter29/src/test/java/com/seaofnodes/simple/Chapter19Test.java
@@ -118,7 +118,7 @@ val hashCode = { !String self ->
 hashCode(new String("Hello, World!"));
 """;
         CodeGen code = new CodeGen(src).driver(Phase.LocalSched);
-        assertEquals("Stop[ return Phi(Region,123456789,(!=0)Phi(Loop,0,(.[]+((Phi_hash<<5)-Phi_hash)))); return MemTop; return MemTop; return Test.String; return Phi(Region,0,1,0,1); return Phi(Region,(!=0)._hashCode,Phi(Region,123456789,(!=0)Phi(Loop,0,(.[]+((Phi_hash<<5)-Phi_hash))))); ]", code.print());
+        assertEquals("Stop[ return Phi(Region,123456789,(!=0)Phi(Loop,0,(((Phi_hash<<5)-Phi_hash)+.[]))); return Test.String; return Phi(Region,0,1,0,1); return Phi(Region,(!=0)._hashCode,Phi(Region,123456789,(!=0)Phi(Loop,0,(((Phi_hash<<5)-Phi_hash)+.[])))); ]", code.print());
         assertEquals("4029215624828139541", Eval2.eval(code,  2));
     }
 
diff --git a/chapter29/src/test/java/com/seaofnodes/simple/Chapter20Test.java b/chapter29/src/test/java/com/seaofnodes/simple/Chapter20Test.java
index 66a318ae..6cf92dc3 100644
--- a/chapter29/src/test/java/com/seaofnodes/simple/Chapter20Test.java
+++ b/chapter29/src/test/java/com/seaofnodes/simple/Chapter20Test.java
@@ -79,6 +79,7 @@ return f(s);
     @Test public void testAllocatorUnion() { com.seaofnodes.simple.codegen.RegAllocTestSupport.union(); }
     @Test public void testAllocatorCopyClobber() throws Exception { com.seaofnodes.simple.codegen.RegAllocTestSupport.copyClobber(); }
     @Test public void testAllocatorCommutativePhi() { com.seaofnodes.simple.codegen.RegAllocTestSupport.commutativePhi(); }
+    @Test public void testAllocatorCommutativeLoop() { com.seaofnodes.simple.codegen.RegAllocTestSupport.commutativeLoop(); }
     @Test public void testAllocatorKills() { com.seaofnodes.simple.codegen.RegAllocTestSupport.killWithoutResult(); }
     @Test public void testAllocatorDependencies() { com.seaofnodes.simple.codegen.RegAllocTestSupport.nullUseMask(); }
     @Test public void testAllocatorCloneClass() { com.seaofnodes.simple.codegen.RegAllocTestSupport.cloneRegisterClass(); }
diff --git a/chapter29/src/test/java/com/seaofnodes/simple/ConstructionGroupTest.java b/chapter29/src/test/java/com/seaofnodes/simple/ConstructionGroupTest.java
index cea6ca91..b5bbfce8 100644
--- a/chapter29/src/test/java/com/seaofnodes/simple/ConstructionGroupTest.java
+++ b/chapter29/src/test/java/com/seaofnodes/simple/ConstructionGroupTest.java
@@ -21,7 +21,7 @@ public class ConstructionGroupTest {
 
     private void rejects(String src, String message) {
         try {
-            new CodeGen(src).parse();
+            new CodeGen(src).driver(CodeGen.Phase.TypeCheck);
             fail("Accepted: "+src);
         } catch( Parser.ParseException e ) {
             assertTrue(e.getMessage(),e.getMessage().contains(message));
@@ -40,12 +40,25 @@ public class ConstructionGroupTest {
             .driver(CodeGen.Phase.Encoding,TestC.CPU_PORT,TestC.CALL_CONVENTION,true,false,0);
     }
 
-    @Test public void testNoIncompleteLookupOrEscape() {
+    @Test public void testIncompleteChildReadAfterInlining() {
         // This lookup supplies a live result. Inlining must not turn self
         // complete inside the body before checking the use of child.
         rejects(parent("child = new Child(self); payload = child.parent==null;")+
             "return new Parent(arg).payload;","incomplete object");
-        rejects(parent("payload = 1; child = new Child(self); int x = child.parent==null;")+"return 0;","incomplete object");
+    }
+
+    @Test public void testInitializerFeedsConstructor() {
+        // Private memory comes from the initializer's real call edge. An
+        // unknown-caller default must neither erase it nor poison its fields.
+        String src = "struct C { int !x = 7; new C = { -> x = x+1; }; }; return new C().x;";
+        for( long seed : new long[]{1,123,987654321} ) {
+            CodeGen code = new CodeGen(src,seed,true).driver(CodeGen.Phase.TypeCheck);
+            assertEquals("8",Eval2.eval(code,0));
+            assertEquals("Stop[ return 8; return Test.C; ]",code.print());
+        }
+    }
+
+    @Test public void testNoIncompleteLookupOrEscape() {
         rejects(parent("payload = 1; child = new Child(self); read(child);")+"return 0;","ordinary function");
         rejects(parent("payload = 1; child = new Child(self);").replace("parent = par;","parent = par; value = par.payload;")+
             "return 0;","incomplete object");
@@ -54,7 +67,7 @@ public class ConstructionGroupTest {
             struct C { int~ x; new C = { -> box.value = self; x = 1; }; };
             return 0;
             ""","ordinary object");
-        rejects("struct C { C next = self; int~ x; new C = { -> int y = next.x; x = 7; }; }; return 0;",
+        rejects("struct C { C next = self; int~ x; new C = { -> x = next.x; }; }; return new C().x;",
             "incomplete object");
     }
 
@@ -115,14 +128,16 @@ public class ConstructionGroupTest {
 
     @Test public void testDeclaredQualifierAndOwnReceiver() {
         // A complete caller does not grant permission to read a ^ formal.
-        rejects("""
+        for( String body : new String[]{"value = par.payload;", "value = par.payload*0;",
+                "int x = par.payload; value = x*0;", "value = par.payload==par.payload;"} )
+            rejects("""
             struct Parent { int payload = 7; };
             struct Child {
                 int value;
-                new Child = { Parent ^par -> value = par.payload; };
+                new Child = { Parent ^par -> BODY };
             };
             return new Child(new Parent).value;
-            ""","incomplete object");
+            """.replace("BODY",body),"incomplete object");
         // The self exception belongs to the receiver, not every pointer of its class.
         rejects("""
             struct C {
@@ -132,4 +147,15 @@ public class ConstructionGroupTest {
             return new C(new C(null)).value;
             ""","incomplete object");
     }
+
+    @Test public void testUnusedIncompleteReadCanDie() {
+        String src = """
+            struct Parent { int payload = 7; };
+            struct Child { int value = 5;
+                new Child = { Parent ^par -> int unused = par.payload; };
+            };
+            return new Child(new Parent).value;
+            """;
+        assertEquals("5",Eval2.eval(new CodeGen(src).driver(CodeGen.Phase.TypeCheck),0));
+    }
 }
diff --git a/chapter29/src/test/java/com/seaofnodes/simple/ConstructorCompletionTest.java b/chapter29/src/test/java/com/seaofnodes/simple/ConstructorCompletionTest.java
index cbb9ee37..a5fc236b 100644
--- a/chapter29/src/test/java/com/seaofnodes/simple/ConstructorCompletionTest.java
+++ b/chapter29/src/test/java/com/seaofnodes/simple/ConstructorCompletionTest.java
@@ -30,10 +30,10 @@ public class ConstructorCompletionTest {
             "int~ x; int y = x*0; new A = { -> x = 7; };",
             // Constructor entry includes the initializer's early return.
             // Its later Store of 2 must not excuse the earlier read of x.
-            "int~ x; if(arg) return 0; x = 1; new A = { -> int y = x; x = 2; };"
+            "int~ x; int seen; if(arg) return 0; x = 1; new A = { -> seen = x; x = 2; };"
         } )
             try {
-                new CodeGen("struct A { "+body+" }; return 0;").parse();
+                new CodeGen("struct A { "+body+" }; return 0;").driver(CodeGen.Phase.TypeCheck);
                 fail("Read a field before its constructor wrote it");
             } catch( Parser.ParseException e ) {
                 assertTrue(e.getMessage(),e.getMessage().contains("might not be initialized"));
@@ -51,7 +51,7 @@ public class ConstructorCompletionTest {
     private void rejects(String fields, String field, boolean explicit) {
         String src = "struct B {}; struct A { "+fields+" }; return 0;";
         try {
-            new CodeGen(src).parse();
+            new CodeGen(src).driver(CodeGen.Phase.TypeCheck);
             fail(src);
         } catch( Parser.ParseException e ) {
             assertEquals("'Test.A' is not fully initialized, field '"+field+
@@ -95,8 +95,8 @@ public class ConstructorCompletionTest {
     @Test public void testNonreturningPaths() {
         // An initializer parsed in dead enclosing code can have TOP memory
         // rather than a struct-shaped result.
-        new CodeGen("while(false) { struct A { int x; }; } return 0;").parse();
-        new CodeGen("struct A { int~ x; new A = { -> while(true) {} }; }; return 0;").parse();
+        new CodeGen("while(false) { struct A { int x; }; } return 0;").driver(CodeGen.Phase.TypeCheck);
+        new CodeGen("struct A { int~ x; new A = { -> while(true) {} }; }; return 0;").driver(CodeGen.Phase.TypeCheck);
         rejects("int~ x; new A = { -> if(arg) return 0; while(true) {} };","x",true);
         CodeGen code = new CodeGen("""
             struct A {
@@ -113,7 +113,7 @@ public class ConstructorCompletionTest {
         // Its Return lacks that field, so completion must consult <init> too.
         rejects("val A = { -> }; B b;","b",true);
         rejects("int~ x; val A = { -> if(arg) x = 1; };","x",true);
-        new CodeGen("struct B {}; struct A { val A = { -> }; B b = new B; }; return 0;").parse();
-        new CodeGen("struct A { val A = { -> while(true) {} }; int~ x; }; return 0;").parse();
+        new CodeGen("struct B {}; struct A { val A = { -> }; B b = new B; }; return 0;").driver(CodeGen.Phase.TypeCheck);
+        new CodeGen("struct A { val A = { -> while(true) {} }; int~ x; }; return 0;").driver(CodeGen.Phase.TypeCheck);
     }
 }
diff --git a/chapter29/src/test/java/com/seaofnodes/simple/TypeTest.java b/chapter29/src/test/java/com/seaofnodes/simple/TypeTest.java
index 68239396..16b75fdc 100644
--- a/chapter29/src/test/java/com/seaofnodes/simple/TypeTest.java
+++ b/chapter29/src/test/java/com/seaofnodes/simple/TypeTest.java
@@ -7,6 +7,26 @@ import static org.junit.Assert.assertSame;
 
 public class TypeTest {
 
+    @Test public void testOpaqueExternalEscapes() {
+        TypeMem defaults = TypeMem.START.makeFrom(XInt.make(2),XInt.make(3));
+        TypeMem prior = TypeMem.START.makeFrom(XInt.make(5),XInt.make(7));
+        TypeMemPtr opaque = TypeMemPtr.makeNullable(TypeStruct.forward("OpaqueExternal"));
+        TypeMem escaped = prior.escapesFrom(opaque,defaults);
+        assertSame(XInt.meet(prior._escFs,defaults._escFs),escaped._escFs);
+        assertSame(XInt.meet(prior._escAs,defaults._escAs),escaped._escAs);
+        // Before type closure the same name might still resolve locally.
+        assertSame(XInt.FULL,prior.escapesFrom(opaque,TypeMem.BOT)._escFs);
+        for( Type unknown : new Type[]{Type.BOTTOM,TypeScalar.BOT,TypePtr.PTR,
+                TypeMemPtr.make(TypeStruct.open("LocalStillOpen"))} ) {
+            TypeMem broad = prior.escapesFrom(unknown,defaults);
+            assertSame(XInt.FULL,broad._escFs);
+            assertSame(XInt.FULL,broad._escAs);
+        }
+        // Concrete private callbacks must not be restricted to public names.
+        TypeFunPtr callback = TypeFunPtr.make1((byte)2,true,TypeFunPtr.TEMPTY,TypeInteger.BOT,11);
+        assertSame(XInt.make(11),TypeMem.START.escapesFrom(callback,defaults)._escFs);
+    }
+
     // Aggregate finality is carried by its fields. Canonicalizing the unused
     // aggregate bit must commute with dual, even for named (non-high) structs.
     @Test public void testAggregateMemoryDual() {
diff --git a/chapter29/src/test/java/com/seaofnodes/simple/codegen/RegAllocTestSupport.java b/chapter29/src/test/java/com/seaofnodes/simple/codegen/RegAllocTestSupport.java
index 292f1ae7..adbb10a5 100644
--- a/chapter29/src/test/java/com/seaofnodes/simple/codegen/RegAllocTestSupport.java
+++ b/chapter29/src/test/java/com/seaofnodes/simple/codegen/RegAllocTestSupport.java
@@ -1,6 +1,7 @@
 package com.seaofnodes.simple.codegen;
 
 import com.seaofnodes.simple.node.*;
+import com.seaofnodes.simple.node.cpus.x86_64_v2.SubX86;
 import com.seaofnodes.simple.node.cpus.x86_64_v2.x86_64_v2;
 import com.seaofnodes.simple.type.TypeInteger;
 import static org.junit.Assert.*;
@@ -124,6 +125,30 @@ public class RegAllocTestSupport {
         assertTrue(BuildLRG.run(0,new RegAlloc(code)));
     }
 
+    public static void commutativeLoop() {
+        for( String op : new String[]{"+","*","^","&","|"} )
+            for( boolean reversed : new boolean[]{false,true} ) {
+                String src = "return { u8[] data -> int h = 1; for(int i = 0; i < data#; i++) " +
+                    "h = ((h<<5)-h) "+op+" data[i]; return h; };";
+                CodeGen code = new CodeGen(src).driver(CodeGen.Phase.LocalSched,"x86_64_v2","SystemV");
+                // Exercise both destructive operands regardless of ideal-node
+                // numbering. The shifted value overlaps the old loop hash.
+                int found = 0;
+                for( CFGNode bb : code._cfg )
+                    for( Node n : bb.outs() )
+                        if( n instanceof MachNode mach && mach.commutes() && mach.twoAddress()==1 &&
+                            (n.in(1) instanceof SubX86 || n.in(2) instanceof SubX86) ) {
+                            if( (n.in(1) instanceof SubX86)==reversed ) n.swap12();
+                            found++;
+                        }
+                assertEquals(op,1,found);
+                code.driver(CodeGen.Phase.RegAlloc,"x86_64_v2","SystemV");
+                checkRegisters(code);
+                assertEquals(op+" reversed="+reversed,8,code._regAlloc._spillScaled);
+                code.encode();
+            }
+    }
+
     private static class CallOp extends CallNode implements MachNode {
         CallOp(Node ctrl, Node def) { super(null,ctrl,null,def,def); }
         @Override public RegMask regmap(int i) { return i==2 ? A : i==3 ? B : null; }