From 2eba63966bdc3d9cfdf41ee085f35cbb6d529bbc Mon Sep 17 00:00:00 2001
From: Cliff Click <cliffc@acm.org>
Date: Wed, 7 Oct 2026 19:10:51 -0700
Subject: Towrds getting RA spill counts comparable

Ignore JIGs.  Get test suites more conical, so reg alloc spill counts are comparable
---
 chapter23/README.md                                | 151 ++++++---------------
 .../main/java/com/seaofnodes/simple/IterPeeps.java |  19 ++-
 .../com/seaofnodes/simple/node/CallEndNode.java    |  93 +++++++++++++
 .../java/com/seaofnodes/simple/Chapter12Test.java  |   2 +
 .../com/seaofnodes/simple/Chapter14FloatTest.java  |   2 +
 .../java/com/seaofnodes/simple/Chapter14Test.java  |   2 +
 .../java/com/seaofnodes/simple/Chapter15Test.java  |   1 +
 .../java/com/seaofnodes/simple/Chapter16Test.java  |   2 +
 .../java/com/seaofnodes/simple/Chapter17bTest.java |   2 +
 .../java/com/seaofnodes/simple/Chapter18Test.java  |   3 +-
 .../java/com/seaofnodes/simple/Chapter19Test.java  |   2 +
 .../java/com/seaofnodes/simple/Chapter20Test.java  |   1 +
 .../com/seaofnodes/simple/Chapter23AllocTest.java  |   3 +
 .../java/com/seaofnodes/simple/Chapter23Test.java  |   1 +
 .../test/java/com/seaofnodes/simple/progs/jig.smp  |   4 +-
 15 files changed, 173 insertions(+), 115 deletions(-)

(limited to 'chapter23')

diff --git a/chapter23/README.md b/chapter23/README.md
index 59ce0dc5..7dbe385b 100644
--- a/chapter23/README.md
+++ b/chapter23/README.md
@@ -204,44 +204,17 @@ print(hello);     // Pass along the read-only version
 ```
 
 What is the type of `hello`?  It is the read-only type of `List`... and `List` is
-a cyclic type.  Let's look at `Type.makeRO`:
-
-```java
-public final Type makeRO() {
-    if( isFinal() ) return this; // First check if already read-only
-    return recurOpen()._makeRO().recurClose();
-}
-```
-
-and `isFinal()`:
-
-```java
-// Are all reachable struct Fields are final?
-public final boolean isFinal() { return recurClose(recurOpen()._isFinal()); }
-boolean _isFinal() { assert _type < TCYCLIC; return true; }
-```
+a cyclic type. Follow the implementation of
+[`Type.makeRO`, `isFinal`, and `_isFinal`](src/main/java/com/seaofnodes/simple/type/Type.java).
 
 We call `recurOpen()` to start/open the recursive walk, do the recursion
 calling `_isFinal()` and end/close the recursive walk, and return a boolean
 answer.  `_isFinal()` is NOT Java final, and is overridden in the Type subclasses.
-Most subclasses just forward the problem along:
-
-`@Override boolean _isFinal() { return _obj._isFinal(); }`
-
-until we hit `TypeStruct`:
-
-```java
-@Override boolean _isFinal() {
-    if( _open ) return false;     // May have more non-final fields
-    if( VISIT.containsKey(_uid) ) // Test: been here before?
-        return true;              // Cycles assume final
-    VISIT.put(_uid,this);         // Set: don't do this again
-    for( Field fld : _fields )
-        if( !fld._isFinal() )
-            return false;
-    return true;
-}
-```
+Subclasses implement the check for their own representation. For example,
+[`TypeMemPtr._isFinal`](src/main/java/com/seaofnodes/simple/type/TypeMemPtr.java)
+reads the pointer's access permission, while
+[`TypeStruct._isFinal`](src/main/java/com/seaofnodes/simple/type/TypeStruct.java)
+walks the fields and handles cycles.
 
 Here we see a common pattern in dealing with cycles: the **test-and-set**.  We
 check for any hard and fast answers (open structs are never read-only; they are
@@ -257,9 +230,9 @@ fields asking the same question recursively.
 For our example, we open the recursion (set a sentinel in `VISIT`), call
 `makeRO` on `struct List`, which then calls `_isFinal` which then checks
 the `_open` flag (not open), checks the `VISIT` (not visited), sets the
-UID in `VISIT` and starts walking the fields.  Fields check:
-
-`@Override boolean _isFinal() { return _final && _t._isFinal(); }`
+UID in `VISIT` and starts walking the fields.
+[`Field._isFinal`](src/main/java/com/seaofnodes/simple/type/Field.java)
+checks both the field's binding and its type.
 
 The first field is `List*? !next`, which is not-final, so immediately returns
 `false`, which stops `_isFinal` on `List` and the whole `isFinal()` call returns
@@ -283,31 +256,13 @@ You can see from the repeated UIDs that `List#2` happens twice... because List
 is cyclic.
 
 Now we do really need to make a cyclic type, and so our `makeRO()` call falls
-into the next line:
-
-`return recurOpen()._makeRO().recurClose();`.
+into the recursive path in
+[`Type.makeRO`](src/main/java/com/seaofnodes/simple/type/Type.java).
 
 Once again `recurOpen` starts/opens our recursive walk, and then we call
-`_makeRO()` which is overridden in every child Type class.  Let's look at
-`TypeStruct`s version:
-
-```java
-// Make a read-only version
-@Override TypeStruct _makeRO() {
-    // Check for already visited
-    TypeStruct ts = (TypeStruct)VISIT.get(_name);
-    if( ts!=null ) return ts;   // Already visited
-    ts = recurPre(_name,_open); // Make a new type with blank fields
-    Field[] flds = ts._fields;
-    for( Field fld : flds ) fld._final = true;
-
-    // Now start the recursion
-    for( int i=0; i<flds.length; i++ )
-        flds[i].setType(_fields[i]._t._makeRO());
-
-    return ts;
-}
-```
+`_makeRO()` which is overridden in the child Type classes. Follow
+[`TypeStruct._makeRO` and `recurPre`](src/main/java/com/seaofnodes/simple/type/TypeStruct.java)
+for the implementation.
 
 First up is the **test-and-set**.  The **test** is by type name; we attempt to
 get a `List` TypeStruct from `VISIT`, and if successful we return early -
@@ -357,8 +312,10 @@ struct List#12 {
 ```
 
 At this point the recursion unwinds and we head into the complex
-`Type.recurClose()`.  You might try single-stepping through the code for a few
-examples; the `TypeTest.testList` test builds these types.  Here is a high
+[`Type.recurClose()`](src/main/java/com/seaofnodes/simple/type/Type.java).
+You might try single-stepping through
+[`TypeTest.testList`](src/test/java/com/seaofnodes/simple/TypeTest.java),
+which builds these types. Here is a high
 level summary:
 
 Copy all the visited types out of `VISIT` for easier management; we might find
@@ -469,64 +426,36 @@ the old buffer after growth is outside this example. Appending
 
 ## RegAlloc improvements: grouping popular uses
 
-Chapter 22 improved color preferences and cheap-spill ordering. This chapter
+Chapter 22 improved color preferences and cheap-spill ordering.  This chapter
 adds a way to split a popular value whose uses demand incompatible registers.
 For example, several shifts may need the same count register while another use
-needs a different register. Sharing one copy for each compatible group can avoid
-inserting a separate copy at every use.
+needs a different register.  Sharing one copy for each compatible group can
+avoid inserting a separate copy at every use.
 
 The allocator applies this to a single-definition live range with an empty
-register mask and more than two fixed-register uses. It intersects overlapping
+register mask and more than two fixed-register uses.  It intersects overlapping
 use masks into groups; narrowing a group keeps it compatible with its earlier
-users, so one pass suffices. Disjoint masks start separate groups. It snapshots
+users, so one pass suffices. Disjoint masks start separate groups.  It snapshots
 distinct users before rewiring their inputs, ignores scheduling-only edges,
 and counts a call once even when the value supplies several arguments.
 
 Grouping declines values used by multiple calls, whose register kills tend to
-undo the benefit of a shared copy. The usual loop-boundary splitting remains
+undo the benefit of a shared copy.  The usual loop-boundary splitting remains
 the fallback, including splitting an existing copy when all uses have the same
-loop depth. Cold-first loop splitting is left for Chapter 24; area/cost spill
+loop depth.  Cold-first loop splitting is left for Chapter 24; area/cost spill
 ranking remains for Chapter 25.
 
-Chapter 21's adjacent-copy forwarding also carries forward: after coloring,
-a sole use in the next instruction can read the source register when its
-operand mask permits it and no two-address tie is broken. The table below
-includes this cleanup and the lazy memory forward port. Cohort 22 now also includes the two zero-move C return
-ABI checks added since the earlier audit (26 entries instead of 24).
-
-Run `make spill-stats` in this directory. All rows below use **this chapter's
-compiler**, seed 123, and frozen source/target combinations from each cohort.
-The Windows run combines x86 SystemV/Win64 and RISC-V/ARM SystemV. Diagnostic
-machine graphs are checked separately and do not contribute to the counts.
-
-| Program cohort | Compilations | Retained moves | Loop-weighted moves |
-|---|---:|---:|---:|
-| Chapter 20 | 39 | 323 | 442 |
-| Chapter 21 | 52 | 433 | 965 |
-| Chapter 22 | 26 | 67 | 67 |
-| Chapter 23 | 30 | 78 | 225 |
-| **Total** | **147** | **901** | **1,699** |
-
-`_spills` counts retained SplitNodes, including register moves; `_spillScaled`
-weights them by `8^loopDepth`. These estimate compiler-generated moves, not
-runtime memory traffic. The reporter prints individual compilations and sums
-by CPU/ABI, and still reports failure when a spill expectation or execution
-check fails.
-
-In the earlier audit, before adjacent-copy forwarding, disabling grouping produced
-**the same 933 moves / 1,745 weighted moves**. The original grouping code also
-has those totals. This suite therefore shows no spill improvement from grouping;
-the reduced machine-graph regression exercises its compatibility and call rules,
-including a null-mask crash in the old implementation. A plausible allocator
-heuristic needs measurements on workloads that reach it before claiming a win.
-
-For the older cohorts alone, Chapter 22's compiler produced 838 moves / 1,496
-weighted moves; this compiler then produced 849 / 1,514. That comparison includes
-changes outside allocation. In particular, Chapter 20's frozen String input
-survives optimization here and costs 16 weighted moves; Chapter 22 eliminated
-it at this seed. It would be misleading to attribute that difference to grouping.
-
-The original 64-bit `person21` and guarded `stringHash21` inputs preserve cohort
-21. The revised String input and two encoding tests enabled in this chapter
-belong to cohort 23. Keeping these cohorts fixed makes subsequent comparisons
-meaningful even as the language and its tests grow.
+Rows are fixed test cohorts; columns are the compiler/allocator chapters.  Each
+cell is the sum of `_spillScaled`: retained split moves, including register
+copies, weighted by loopDepth.  Lower is better.  **# tests counts
+compilations** (program/CPU/ABI cases), including zero-spill cases, rather than
+JUnit methods.  The count and membership of each row stay fixed across columns.
+
+<!-- spill-matrix:start -->
+| Test cohort | # tests | Ch 20 | Ch 21 | Ch 22 | Ch 23 |
+|---|---:|---:|---:|---:|---:|
+| Ch 20 | 39 | 360 | 576 | 430 | 442 |
+| Ch 21 | 52 |  | 1,072 | 960 | 961 |
+| Ch 22 | 26 |  |  | 63 | 63 |
+| Ch 23 | 24 |  |  |  | 103 |
+<!-- spill-matrix:end -->
diff --git a/chapter23/src/main/java/com/seaofnodes/simple/IterPeeps.java b/chapter23/src/main/java/com/seaofnodes/simple/IterPeeps.java
index c873e74c..c4b96c5c 100644
--- a/chapter23/src/main/java/com/seaofnodes/simple/IterPeeps.java
+++ b/chapter23/src/main/java/com/seaofnodes/simple/IterPeeps.java
@@ -47,7 +47,12 @@ public class IterPeeps {
 
     private final WorkList<Node> _work;
 
-    public IterPeeps( long seed ) { _work = new WorkList<>(seed); }
+    private final WorkList<CallEndNode> _workInline;
+
+    public IterPeeps( long seed ) {
+        _work = new WorkList<>(seed);
+        _workInline = new WorkList<>(seed);
+    }
 
     @SuppressWarnings("unchecked")
     public <N extends Node> N add( N n ) { return (N)_work.push(n); }
@@ -58,12 +63,24 @@ public class IterPeeps {
      * Iterate peepholes to a fixed point
      */
     public void iterate( CodeGen code ) {
+        while( true ) {
+            iteratePeeps(code);
+            CallEndNode cend;
+            while( (cend=_workInline.pop())!=null )
+                if( cend.inlineSmall() ) break;
+            if( cend==null ) return;
+        }
+    }
+
+    // Only try growing inlines once the shrinking peepholes reach a fixed point.
+    private void iteratePeeps( CodeGen code ) {
         assert progressOnList(code);
         int cnt=0;
 
         Node n;
         while( (n=_work.pop()) != null ) {
             if( n.isDead() )  continue;
+            if( n instanceof CallEndNode cend ) _workInline.push(cend);
             cnt++;              // Useful for debugging, searching which peephole broke things
             var obs = CodeGen.CODE._obs;
             if( obs != null ) obs.before(n);
diff --git a/chapter23/src/main/java/com/seaofnodes/simple/node/CallEndNode.java b/chapter23/src/main/java/com/seaofnodes/simple/node/CallEndNode.java
index cdf12a12..e83e5cba 100644
--- a/chapter23/src/main/java/com/seaofnodes/simple/node/CallEndNode.java
+++ b/chapter23/src/main/java/com/seaofnodes/simple/node/CallEndNode.java
@@ -108,6 +108,99 @@ public class CallEndNode extends CFGNode implements MultiNode {
         return null;
     }
 
+    // Clone only tiny, straight-line boilerplate, after ordinary peeps settle.
+    // Larger bodies still use the existing single-caller, non-cloning inline.
+    public boolean inlineSmall() {
+        if( isDead() || _folding || nIns()!=2 || !(in(0) instanceof CallNode call) ) return false;
+        Node fptr = call.fptr();
+        if( !(fptr instanceof ConstantNode) ||
+            !(fptr._type instanceof TypeFunPtr tfp && tfp.notNull() && tfp.isConstant()) )
+            { addDep(fptr); return false; }
+        if( call.err()!=null ) return false;
+        ReturnNode ret = (ReturnNode)in(1);
+        FunNode fun = ret.fun();
+        if( fun._folding ) return false;
+        int len = smallBody(fun);
+        if( len==0 ) return false;
+        // All callers consume the three normal return projections.
+        for( Node use : _outputs )
+            if( !((use instanceof ProjNode p && p._idx>=0 && p._idx<3) ||
+                  (use instanceof CProjNode cp && cp._idx==0)) ) return false;
+
+        // Substitute control and arguments directly; no new function identity,
+        // parameter Phis, or return address is needed for this straight line.
+        Node[] copy = new Node[len];
+        for( int i=0; i<len; i++ ) {
+            Node n = TINYBODY[i];
+            copy[i] = n==fun ? call.ctrl() :
+                n instanceof ParmNode parm ? (parm._idx==0 ? null : call.arg(parm._idx)) :
+                n==ret ? null : n.copyEmpty();
+        }
+        for( int i=0; i<len; i++ ) {
+            Node n = TINYBODY[i];
+            if( n instanceof StoreNode || n instanceof MemMergeNode ) {
+                for( Node in : n._inputs ) copy[i].addDef(mapped(in,copy));
+                CodeGen.CODE.add(copy[i]);
+            }
+        }
+        Node[] result = new Node[3];
+        for( int i=0; i<3; i++ ) result[i] = mapped(ret.in(i),copy).keep();
+        keep();
+        call.unlink_all();
+        CodeGen.CODE.add(fun);
+        CodeGen.CODE.addAll(fun._outputs);
+        // subsume kills each projection; retain CallEnd until all are replaced.
+        while( nOuts()>1 ) {
+            Node use = out(0)==null ? out(1) : out(0);
+            int idx = use instanceof ProjNode p ? p._idx : ((CProjNode)use)._idx;
+            CodeGen.CODE.addAll(use._outputs);
+            use.subsume(result[idx]);
+        }
+        unkill();
+        for( Node n : result ) n.unkill();
+        CodeGen.CODE.invalidateIDepthCaches();
+        return true;
+    }
+
+    private static Node mapped(Node n, Node[] copy) {
+        for( int i=0; i<copy.length; i++ )
+            if( TINYBODY[i]==n ) return copy[i];
+        return n;               // Constants outside the body are shared.
+    }
+
+    // Bounded recognition of initializer boilerplate. Walk uses from the entry
+    // and stop at Return, never following callers or constant inputs. This also
+    // avoids scanning sparse MemMerge input arrays while a large body shrinks.
+    // Watch this small prefix, including an unsupported node that may fold.
+    private static final Node[] TINYBODY = new Node[15]; // Tiny worklist
+    private int smallBody(FunNode fun) {
+        ReturnNode ret = fun.ret();
+        for( Node in : ret._inputs )
+            if( in!=null ) addDep(in);
+        if( ret.ctrl()!=fun ) return 0;
+        TINYBODY[0] = fun;
+        int len=1;
+        for( int i=0; i<len; i++ ) {
+            Node n = TINYBODY[i];
+            addDep(n);
+            if( n==ret ) continue;
+            if( n instanceof ParmNode parm && parm.region()!=fun ) return 0;
+            if( n!=fun && !(n instanceof ParmNode) &&
+                !(n instanceof StoreNode) && !(n instanceof MemMergeNode) )
+                return 0;
+            if( n.nOuts()>TINYBODY.length ) return 0;
+            for( Node use : n._outputs ) {
+                if( use==null ) continue;
+                int j=0;
+                while( j<len && TINYBODY[j]!=use ) j++;
+                if( j<len ) continue;
+                if( len==TINYBODY.length ) { addDep(use); return 0; }
+                TINYBODY[len++] = use;
+            }
+        }
+        return len;
+    }
+
     @Override public Node pcopy(int idx) {
         return _folding ? in(1).in(idx) : null;
     }
diff --git a/chapter23/src/test/java/com/seaofnodes/simple/Chapter12Test.java b/chapter23/src/test/java/com/seaofnodes/simple/Chapter12Test.java
index 041e0d06..ac3b81ec 100644
--- a/chapter23/src/test/java/com/seaofnodes/simple/Chapter12Test.java
+++ b/chapter23/src/test/java/com/seaofnodes/simple/Chapter12Test.java
@@ -1,11 +1,13 @@
 package com.seaofnodes.simple;
 
 import com.seaofnodes.simple.codegen.CodeGen;
+import org.junit.Ignore;
 import org.junit.Test;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.fail;
 
 public class Chapter12Test {
+    @Ignore
     @Test
     public void testJig() {
         CodeGen code = new CodeGen(
diff --git a/chapter23/src/test/java/com/seaofnodes/simple/Chapter14FloatTest.java b/chapter23/src/test/java/com/seaofnodes/simple/Chapter14FloatTest.java
index 23d0ef37..6377bc14 100644
--- a/chapter23/src/test/java/com/seaofnodes/simple/Chapter14FloatTest.java
+++ b/chapter23/src/test/java/com/seaofnodes/simple/Chapter14FloatTest.java
@@ -2,6 +2,7 @@ package com.seaofnodes.simple;
 
 import com.seaofnodes.simple.codegen.CodeGen;
 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;
@@ -47,6 +48,7 @@ public class Chapter14FloatTest {
     }
 
 
+    @Ignore
     @Test
     public void testJig() {
         CodeGen code = new CodeGen(
diff --git a/chapter23/src/test/java/com/seaofnodes/simple/Chapter14Test.java b/chapter23/src/test/java/com/seaofnodes/simple/Chapter14Test.java
index da7e50bc..c342eeed 100644
--- a/chapter23/src/test/java/com/seaofnodes/simple/Chapter14Test.java
+++ b/chapter23/src/test/java/com/seaofnodes/simple/Chapter14Test.java
@@ -2,12 +2,14 @@ package com.seaofnodes.simple;
 
 import com.seaofnodes.simple.codegen.CodeGen;
 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;
 
 public class Chapter14Test {
 
+    @Ignore
     @Test
     public void testJig() {
         CodeGen code = new CodeGen(
diff --git a/chapter23/src/test/java/com/seaofnodes/simple/Chapter15Test.java b/chapter23/src/test/java/com/seaofnodes/simple/Chapter15Test.java
index 66a50d0f..d0a42ccf 100644
--- a/chapter23/src/test/java/com/seaofnodes/simple/Chapter15Test.java
+++ b/chapter23/src/test/java/com/seaofnodes/simple/Chapter15Test.java
@@ -10,6 +10,7 @@ import static org.junit.Assert.*;
 
 public class Chapter15Test {
 
+    @Ignore
     @Test
     public void testJig() {
         CodeGen code = new CodeGen(
diff --git a/chapter23/src/test/java/com/seaofnodes/simple/Chapter16Test.java b/chapter23/src/test/java/com/seaofnodes/simple/Chapter16Test.java
index 692ac8d5..f73cbf57 100644
--- a/chapter23/src/test/java/com/seaofnodes/simple/Chapter16Test.java
+++ b/chapter23/src/test/java/com/seaofnodes/simple/Chapter16Test.java
@@ -1,12 +1,14 @@
 package com.seaofnodes.simple;
 
 import com.seaofnodes.simple.codegen.CodeGen;
+import org.junit.Ignore;
 import org.junit.Test;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.fail;
 
 public class Chapter16Test {
 
+    @Ignore
     @Test
     public void testJig() {
         CodeGen code = new CodeGen(
diff --git a/chapter23/src/test/java/com/seaofnodes/simple/Chapter17bTest.java b/chapter23/src/test/java/com/seaofnodes/simple/Chapter17bTest.java
index 59bd3b0c..24dc0229 100644
--- a/chapter23/src/test/java/com/seaofnodes/simple/Chapter17bTest.java
+++ b/chapter23/src/test/java/com/seaofnodes/simple/Chapter17bTest.java
@@ -1,12 +1,14 @@
 package com.seaofnodes.simple;
 
 import com.seaofnodes.simple.codegen.CodeGen;
+import org.junit.Ignore;
 import org.junit.Test;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.fail;
 
 public class Chapter17bTest {
 
+    @Ignore
     @Test
     public void testJig() {
         CodeGen code = new CodeGen(
diff --git a/chapter23/src/test/java/com/seaofnodes/simple/Chapter18Test.java b/chapter23/src/test/java/com/seaofnodes/simple/Chapter18Test.java
index e3dd222d..902344ed 100644
--- a/chapter23/src/test/java/com/seaofnodes/simple/Chapter18Test.java
+++ b/chapter23/src/test/java/com/seaofnodes/simple/Chapter18Test.java
@@ -115,6 +115,7 @@ public class Chapter18Test {
     }
 
 
+    @Ignore
     @Test
     public void testJig() {
         CodeGen code = new CodeGen(
@@ -454,7 +455,7 @@ if (i2i) return i2i(arg);
 return f2f(o)(1);
 """);
         code.driver(Phase.LocalSched);
-        assertEquals("Stop[ return Phi(Region,#2,#2); return Parm_i(i2i.o,i64); ]", code._stop.toString());
+        assertEquals("Stop[ return Phi(Region,#2,1); return Parm_i(i2i.o,i64); ]", code._stop.toString());
         assertEquals("1", Eval2.eval(code,  2));
     }
 
diff --git a/chapter23/src/test/java/com/seaofnodes/simple/Chapter19Test.java b/chapter23/src/test/java/com/seaofnodes/simple/Chapter19Test.java
index d1e5fa70..23b45e46 100644
--- a/chapter23/src/test/java/com/seaofnodes/simple/Chapter19Test.java
+++ b/chapter23/src/test/java/com/seaofnodes/simple/Chapter19Test.java
@@ -8,6 +8,7 @@ import com.seaofnodes.simple.codegen.CodeGen;
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import org.junit.Ignore;
 import org.junit.Test;
 import static org.junit.Assert.*;
 
@@ -32,6 +33,7 @@ public class Chapter19Test {
     }
 
 
+    @Ignore
     @Test
     public void testJig() {
         CodeGen code = new CodeGen("""
diff --git a/chapter23/src/test/java/com/seaofnodes/simple/Chapter20Test.java b/chapter23/src/test/java/com/seaofnodes/simple/Chapter20Test.java
index 36f2f7b0..08a23ef0 100644
--- a/chapter23/src/test/java/com/seaofnodes/simple/Chapter20Test.java
+++ b/chapter23/src/test/java/com/seaofnodes/simple/Chapter20Test.java
@@ -92,6 +92,7 @@ return f(s);
     }
 
 
+    @Ignore
     @Test
     public void testJig() {
         CodeGen code = new CodeGen("return 0;");
diff --git a/chapter23/src/test/java/com/seaofnodes/simple/Chapter23AllocTest.java b/chapter23/src/test/java/com/seaofnodes/simple/Chapter23AllocTest.java
index 7f4b86d5..f3cc7512 100644
--- a/chapter23/src/test/java/com/seaofnodes/simple/Chapter23AllocTest.java
+++ b/chapter23/src/test/java/com/seaofnodes/simple/Chapter23AllocTest.java
@@ -2,6 +2,7 @@ package com.seaofnodes.simple;
 
 import java.io.IOException;
 import java.nio.file.*;
+import org.junit.Ignore;
 import org.junit.Test;
 
 // Revised or newly enabled allocation examples in Chapter 23.
@@ -14,6 +15,7 @@ public class Chapter23AllocTest {
         Chapter23Test.testCPU(src,"arm"      , "SystemV", 1,null);
     }
 
+    @Ignore
     @Test
     public void testJig21() throws IOException {
         String src = Files.readString(Path.of("src/test/java/com/seaofnodes/simple/progs/jig.smp"));
@@ -22,6 +24,7 @@ public class Chapter23AllocTest {
         Chapter23Test.testCPU(src,"arm"      , "SystemV",-1,null);
     }
 
+    @Ignore
     @Test
     public void testJig22() throws IOException {
         String src = Files.readString(Path.of("src/test/java/com/seaofnodes/simple/progs/jig.smp"));
diff --git a/chapter23/src/test/java/com/seaofnodes/simple/Chapter23Test.java b/chapter23/src/test/java/com/seaofnodes/simple/Chapter23Test.java
index 58b8d3e4..0feaa5de 100644
--- a/chapter23/src/test/java/com/seaofnodes/simple/Chapter23Test.java
+++ b/chapter23/src/test/java/com/seaofnodes/simple/Chapter23Test.java
@@ -83,6 +83,7 @@ public class Chapter23Test {
         }
     }
 
+    @Ignore
     @Test
     public void testJig() throws IOException {
         String src =
diff --git a/chapter23/src/test/java/com/seaofnodes/simple/progs/jig.smp b/chapter23/src/test/java/com/seaofnodes/simple/progs/jig.smp
index f7a5d202..29987d8e 100644
--- a/chapter23/src/test/java/com/seaofnodes/simple/progs/jig.smp
+++ b/chapter23/src/test/java/com/seaofnodes/simple/progs/jig.smp
@@ -1,5 +1,5 @@
 // -*- mode: java;  -*-
-val fib = {int n ->
+val _fib = {int n ->
     int temp=0;
     int f1=1;
     int f2=1;
@@ -13,4 +13,4 @@ val fib = {int n ->
     return f2;
 };
 
-fib(10);
+_fib(10);
-- 
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