Towrds getting RA spill counts comparable

Ignore JIGs.  Get test suites more conical, so reg alloc spill counts are comparable

36 files changed, 184 insertions, 180 deletions

diff --git a/chapter25/README.md b/chapter25/README.md
index bfe48809..ec8a8ea8 100644
--- a/chapter25/README.md
+++ b/chapter25/README.md
@@ -170,77 +170,41 @@ is not equivalent to this chapter's full `make tests`.
 
 ## RegAlloc improvements: live-range area and split cost
 
-Chapter 24 tried cold copies before splitting a loop Phi's hot edges. This
+Chapter 24 tried cold copies before splitting a loop Phi's hot edges.  This
 chapter also estimates how much scheduled code a spill frees from register
-pressure, divided by the estimated cost of the new copies. Callee-save ranges
-cover a whole function. Cloneable constants can be rebuilt nearer their uses.
+pressure, divided by the estimated cost of the new copies.  Callee-save ranges
+cover a whole function.  Cloneable constants can be rebuilt nearer their uses.
 Copies inside loops cost more: the estimate weights them by `8^loopDepth`.
 These are inexpensive approximations, especially for values with many uses.
 
-The other Chapter 25 conflict-handling rules remain here: direct splitting of
-several fixed-register uses and deeper splits for some multi-definition ranges.
-Their size thresholds are heuristics, not general invariants to backport to the
-first allocator. Shared legality fixes still start in the earliest affected
-chapter. The final audit corrected fixed-neighbor color bias in 20-25, narrow
-store masks in 20-21, and ARM register-bank/float-memory encoding in 21-25.
-
-Chapter 21's adjacent-copy forwarding carries forward here as well: a copy
-used only by the next instruction is removed when the operand accepts its
-source register and is not tied to the instruction's result.
-
-The table below is the complete 2026-10-02 replay, after repairing three saved
-String sources with explicit constructors for their required `cs` field.
-All 212 historical entries now pass. This establishes a new baseline after the
-fixture adaptations and recent compiler corrections; it is not an allocator-only
-comparison with the earlier audit. The [backport record](../docs/chapter-backports.md)
-retains the older partial comparisons.
-
-Run `make spill-stats`. Each row uses **Chapter 25's compiler**. The first five
-rows preserve the earlier 212 program/target entries, adapted to this chapter's
-syntax and library organization; the [fixture notes](src/test/java/com/seaofnodes/simple/spill/README.md)
-list those adaptations and the measurement limits. They use optimizer seed 123.
-The last row includes thirteen recorded allocations from `Chapter25Test` at its existing
-seeds plus a fresh system-library compilation at the driver's seed 456. Reusing
-`sys.o` must not make that substantial workload disappear from the measurements.
-These results are from Windows x86-64; earlier cohorts also include RISC-V/ARM
-SystemV and x86 SystemV. The reporter prints per-target totals as well.
-
-| Program cohort | Compilations | Split/move count | Loop-weighted count |
-|---|---:|---:|---:|
-| Chapter 20 | 39 | 375 | 606 |
-| Chapter 21 | 52 | 479 | 1,172 |
-| Chapter 22 | 24 | 103 | 103 |
-| Chapter 23 | 30 | 129 | 353 |
-| Chapter 24 | 67 | 696 | 1,410 |
-| Chapter 25 | 14 | 786 | 1,815 |
-| **Total** | **226** | **2,568** | **5,459** |
-
-`_spills` counts retained SplitNodes, including register-to-register moves;
-`_spillScaled` applies the loop weight. Neither measures just memory traffic.
-The old cohorts are allocation replays with register-legality checks, not reruns
-of their native harnesses. All 23 `Chapter25Test` tests pass, including their
-native/result checks, with no spill-golden failures.
-Use `make -j 4 tests` for the full chapter, including inherited emulator tests.
-
-### Comments on the measurements
-
-The earlier allocator audit found no uniform improvement. Substituting Chapter
-24's ranking while keeping the rest of that compiler unchanged saved five moves on the 221
-client compilations (2,206 / 4,719 versus 2,211 / 4,724), but failed to allocate
-the system library within eight rounds. It is therefore an incomplete comparison,
-not a lower valid whole-suite total. The existing area/cost ranking is retained;
-the round limit and correctness checks are unchanged. The system library itself
-contributed 386 moves / 855 weighted moves in that audit; the current replay
-measures 373 / 828.
-
-A trial that favored all multi-use cloneable constants saved one move against
-the earlier ranking on those clients, but also failed the fresh library build.
-It was rejected. This is why both aggregate statistics and complete compilation
-and execution checks matter; a favorable subtotal cannot justify a change.
-
-In that earlier audit, the historical-cohort total rose from Chapter 24's
-1,332 / 2,956 to Chapter 25's 1,814 / 3,753.
-Chapter 25 adds class initializers, module ownership, different escape analysis,
-and syntax/library adaptations. These are different machine graphs; the increase
-cannot be attributed to allocator quality alone. Compare a heuristic within one
-compiler and fixed corpus before drawing conclusions from the chapter tables.
+A single-use function address in the same block gets priority for
+rematerialization when it is separated from its use.  Moving that address
+calculation next to the use adds no instruction and avoids preserving a
+callee-save register merely to hold the constant.  Adjacent uses and multi-use
+addresses retain the area/cost ranking.
+
+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 24 | Ch 25 |
+|---|---:|---:|---:|---:|---:|---:|---:|
+| Ch 20 | 39 | 360 | 576 | 430 | 442 | 441 | 491 |
+| Ch 21 | 52 |  | 1,072 | 960 | 961 | 948 | 1,077 |
+| Ch 22 | 26 |  |  | 63 | 63 | 63 | 71 |
+| Ch 23 | 24 |  |  |  | 103 | 103 | 152 |
+| Ch 24 | 58 |  |  |  |  | 1,387 | 1,503 |
+| Ch 25 | 14 |  |  |  |  |  | 1,862 |
+<!-- spill-matrix:end -->
+
+
+Chapter25 introduces several features, which when run on the older tests
+generate a lot more code, which in turn generates more spills.
+
+Class initialization, inlining, escape analysis, and library adaptations
+all change the graphs.  To help with this, we adjust the inlining
+heursitics to try and get all the boilerplate to inline and optimize.
+
diff --git a/chapter25/src/main/java/com/seaofnodes/simple/codegen/IFG.java b/chapter25/src/main/java/com/seaofnodes/simple/codegen/IFG.java
index 6145910c..bcdb14bf 100644
--- a/chapter25/src/main/java/com/seaofnodes/simple/codegen/IFG.java
+++ b/chapter25/src/main/java/com/seaofnodes/simple/codegen/IFG.java
@@ -457,6 +457,13 @@ abstract public class IFG {
             int area = cfg != use.cfg0()
                 ? functionArea(lrg._fun,alloc)
                 : cfg._outputs.find(use)-cfg._outputs.find(def)-1;
+            // A single-use function address can move next to its use without
+            // adding an instruction.  Prefer that to saving a callee-save
+            // register just to hold the address.  Stay in the same block and
+            // require a gap so the clone makes progress.
+            if( def instanceof FunPtrNode && !lrg._multiUse &&
+                cfg == use.cfg0() && area > 0 )
+                return 1000000;
             if( area > 0 )
                 return areaScore(area,loopCost(use));
         }
diff --git a/chapter25/src/main/java/com/seaofnodes/simple/node/CallEndNode.java b/chapter25/src/main/java/com/seaofnodes/simple/node/CallEndNode.java
index 162f9c24..35180fea 100644
--- a/chapter25/src/main/java/com/seaofnodes/simple/node/CallEndNode.java
+++ b/chapter25/src/main/java/com/seaofnodes/simple/node/CallEndNode.java
@@ -179,10 +179,12 @@ public class CallEndNode extends CFGNode implements MultiNode {
             { addDep(fptr); return -1; }
 
         // Encouraged inlining because small size and constructor.
-        int maxSize = fun._name!=null && fun.isInit() && !fun.isClz() ? 200 : 100;
-        if( fun._approxUIDs >= maxSize )
-            return -2;          // Try later (if shrinking helps)
-        if( fun.body().cardinality() >= maxSize )
+        int maxSize = fun.inlineLimit();
+        // A large parse can leave only a tiny initializer.  Recognize that
+        // without repeatedly walking the whole body while it shrinks.
+        if( fun._approxUIDs >= maxSize ) {
+            if( !smallBody(fun) ) return -1;
+        } else if( fun.body().cardinality() >= maxSize )
             return -1;          // Try later (if cleanup makes the real body small enough)
 
         // Can be cloned but not trivial
@@ -192,6 +194,39 @@ public class CallEndNode extends CFGNode implements MultiNode {
         return 1;
     }
 
+    // Bounded, conservative recognition of straight-line 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.
+    // Watch only this small prefix, including an unsupported node that may fold.
+    private static final Node[] TINYBODY = new Node[15]; // Tiny worklist
+    private boolean smallBody(FunNode fun) {
+        ReturnNode ret = fun.ret();
+        for( Node in : ret._inputs )
+            if( in!=null ) addDep(in);
+        if( ret.ctrl()!=fun ) return false;
+        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 false;
+            if( n!=fun && !(n instanceof ParmNode) &&
+                !(n instanceof StoreNode) && !(n instanceof MemMergeNode) )
+                return false;                             // Something unexpected
+            if( n.nOuts()>TINYBODY.length ) return false; // Too big
+            for( Node use : n._outputs ) {
+                if( use==null ) continue;
+                int j=0;
+                while( j<len && TINYBODY[j]!=use ) j++;
+                if( j<len ) continue; // Already in TINYBODY
+                if( len==TINYBODY.length ) { addDep(use); return false; } // Too big
+                TINYBODY[len++] = use;  // Add to worklist
+            }
+        }
+        return true;
+    }
+
     public void doInline() {
         assert _inline > 0;    // Only called when possible to inline
 
diff --git a/chapter25/src/main/java/com/seaofnodes/simple/node/FunNode.java b/chapter25/src/main/java/com/seaofnodes/simple/node/FunNode.java
index 29e9900a..b74f9e6b 100644
--- a/chapter25/src/main/java/com/seaofnodes/simple/node/FunNode.java
+++ b/chapter25/src/main/java/com/seaofnodes/simple/node/FunNode.java
@@ -221,6 +221,11 @@ public class FunNode extends RegionNode {
     public static boolean isInit(String name ) { return name!=null && name.endsWith("init>"); }
     public static boolean isInstance(String name ) { return name!=null && name.endsWith(".<init>"); }
 
+    // Allocation factories and instance initializers carry extra memory boilerplate.
+    public int inlineLimit() {
+        return isInstance() || (_name!=null && _name.endsWith(".<new>")) ? 200 : 100;
+    }
+
     // Function is public (callable from Start directly).
     public boolean isPublic( ) {
         // Never true for anonymous functions
@@ -316,7 +321,7 @@ public class FunNode extends RegionNode {
     FunNode copyBody() {
         // Build the function body BitSet
         BitSet body = body();
-        assert body.cardinality() < 100;
+        assert body.cardinality() < inlineLimit();
         // Walk the body, cloning
         IdentityHashMap<Node,Node> map = new IdentityHashMap<>();
         BitSet visit = CodeGen.CODE.visit();
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/Chapter12Test.java b/chapter25/src/test/java/com/seaofnodes/simple/Chapter12Test.java
index f1ff2e14..07cd3831 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/Chapter12Test.java
+++ b/chapter25/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/chapter25/src/test/java/com/seaofnodes/simple/Chapter14FloatTest.java b/chapter25/src/test/java/com/seaofnodes/simple/Chapter14FloatTest.java
index 80f70ff8..c1354e34 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/Chapter14FloatTest.java
+++ b/chapter25/src/test/java/com/seaofnodes/simple/Chapter14FloatTest.java
@@ -1,6 +1,7 @@
 package com.seaofnodes.simple;
 
 import com.seaofnodes.simple.codegen.CodeGen;
+import org.junit.Ignore;
 import org.junit.Test;
 import static org.junit.Assert.assertEquals;
 
@@ -45,6 +46,7 @@ public class Chapter14FloatTest {
     }
 
 
+    @Ignore
     @Test
     public void testJig() {
         CodeGen code = new CodeGen(
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/Chapter14Test.java b/chapter25/src/test/java/com/seaofnodes/simple/Chapter14Test.java
index f0ad6c2d..086bb824 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/Chapter14Test.java
+++ b/chapter25/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/chapter25/src/test/java/com/seaofnodes/simple/Chapter15Test.java b/chapter25/src/test/java/com/seaofnodes/simple/Chapter15Test.java
index 85dc7b47..f363847a 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/Chapter15Test.java
+++ b/chapter25/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/chapter25/src/test/java/com/seaofnodes/simple/Chapter16Test.java b/chapter25/src/test/java/com/seaofnodes/simple/Chapter16Test.java
index 23ec549d..91e5cd38 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/Chapter16Test.java
+++ b/chapter25/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/chapter25/src/test/java/com/seaofnodes/simple/Chapter17bTest.java b/chapter25/src/test/java/com/seaofnodes/simple/Chapter17bTest.java
index 62d0b261..b6768d6f 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/Chapter17bTest.java
+++ b/chapter25/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/chapter25/src/test/java/com/seaofnodes/simple/Chapter18Test.java b/chapter25/src/test/java/com/seaofnodes/simple/Chapter18Test.java
index adc05f6f..82f99fc0 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/Chapter18Test.java
+++ b/chapter25/src/test/java/com/seaofnodes/simple/Chapter18Test.java
@@ -115,6 +115,7 @@ public class Chapter18Test {
     }
 
 
+    @Ignore
     @Test
     public void testJig() {
         CodeGen code = new CodeGen(
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/Chapter19Test.java b/chapter25/src/test/java/com/seaofnodes/simple/Chapter19Test.java
index 8cd5137c..cb7d492f 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/Chapter19Test.java
+++ b/chapter25/src/test/java/com/seaofnodes/simple/Chapter19Test.java
@@ -6,6 +6,7 @@ import com.seaofnodes.simple.type.*;
 import com.seaofnodes.simple.codegen.CodeGen.Phase;
 import com.seaofnodes.simple.codegen.CodeGen;
 import java.io.IOException;
+import org.junit.Ignore;
 import org.junit.Test;
 import static org.junit.Assert.*;
 
@@ -30,6 +31,7 @@ public class Chapter19Test {
     }
 
 
+    @Ignore
     @Test
     public void testJig() {
         CodeGen code = new CodeGen("""
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/Chapter20Test.java b/chapter25/src/test/java/com/seaofnodes/simple/Chapter20Test.java
index 262b8604..40e9172e 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/Chapter20Test.java
+++ b/chapter25/src/test/java/com/seaofnodes/simple/Chapter20Test.java
@@ -4,6 +4,7 @@ import com.seaofnodes.simple.codegen.RegAllocTestSupport.CheckedCodeGen;
 
 
 import com.seaofnodes.simple.codegen.CodeGen;
+import org.junit.Ignore;
 import org.junit.Test;
 import static org.junit.Assert.*;
 
@@ -87,6 +88,7 @@ return f(s);
     }
 
 
+    @Ignore
     @Test
     public void testJig() {
         CodeGen code = new CodeGen("return 0;");
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/Chapter21Test.java b/chapter25/src/test/java/com/seaofnodes/simple/Chapter21Test.java
index ba71d1dd..8010e245 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/Chapter21Test.java
+++ b/chapter25/src/test/java/com/seaofnodes/simple/Chapter21Test.java
@@ -10,6 +10,7 @@ import com.seaofnodes.simple.node.cpus.arm.arm;
 import com.seaofnodes.simple.node.cpus.riscv.riscv;
 import com.seaofnodes.simple.util.SB;
 import java.io.IOException;
+import org.junit.Ignore;
 import org.junit.Test;
 import static org.junit.Assert.*;
 
@@ -257,6 +258,7 @@ public class Chapter21Test {
     }
 
 
+    @Ignore
     @Test
     public void testJig() throws IOException {
         String src =
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/Chapter22Test.java b/chapter25/src/test/java/com/seaofnodes/simple/Chapter22Test.java
index ed678334..e8c080fd 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/Chapter22Test.java
+++ b/chapter25/src/test/java/com/seaofnodes/simple/Chapter22Test.java
@@ -96,6 +96,7 @@ public class Chapter22Test {
     }
 
 
+    @Ignore
     @Test
     public void testJig() throws IOException {
         String src = """
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/Chapter24Test.java b/chapter25/src/test/java/com/seaofnodes/simple/Chapter24Test.java
index 05dfe1c2..ef65c6d9 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/Chapter24Test.java
+++ b/chapter25/src/test/java/com/seaofnodes/simple/Chapter24Test.java
@@ -12,6 +12,7 @@ import com.seaofnodes.simple.type.*;
 import com.seaofnodes.simple.codegen.CodeGen;
 import com.seaofnodes.simple.node.cpus.riscv.riscv;
 import java.io.IOException;
+import org.junit.Ignore;
 import org.junit.Test;
 import static org.junit.Assert.*;
 
@@ -36,6 +37,7 @@ public class Chapter24Test {
     }
 
 
+    @Ignore
     @Test
     public void testJig() throws IOException {
         String src = "int v0=0;  v0 = arg && 0== 0 !=0;";
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/Chapter25Test.java b/chapter25/src/test/java/com/seaofnodes/simple/Chapter25Test.java
index dce70897..354c6ec2 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/Chapter25Test.java
+++ b/chapter25/src/test/java/com/seaofnodes/simple/Chapter25Test.java
@@ -372,11 +372,11 @@ public class Chapter25Test {
 
         String obj = "build/objs/"+base+".o";
         String exe = "build/objs/"+base+(TestC.OS.startsWith("Windows") ? ".exe" : "");
-        String syms = TestC.exec(10,"nm",obj);
+        String syms = TestC.exec(TestC.TEST_TIMEOUT_SECONDS,"nm",obj);
         assertTrue(syms, syms.contains(" U sys.io.p_noInline"));
 
         TestC.linkExe(obj,null,null,new Ary<>(new String[]{SYS_FILE.toString()}),exe);
-        String rez = TestC.exec(10,exe);
+        String rez = TestC.exec(TestC.TEST_TIMEOUT_SECONDS,exe);
         assertEquals(expected,rez);
     }
 
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/TestC.java b/chapter25/src/test/java/com/seaofnodes/simple/TestC.java
index 5e32c8c6..64518b0d 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/TestC.java
+++ b/chapter25/src/test/java/com/seaofnodes/simple/TestC.java
@@ -16,6 +16,7 @@ import static org.junit.Assert.*;
 // Call a C driver program, which calls a Simple-generated .o, and self-checks.
 // Expects GCC from the default CLI, compiles C, compiles Simple, links and runs.
 public abstract class TestC {
+    public static final int TEST_TIMEOUT_SECONDS = 60;
 
     public static final String OS  = System.getProperty("os.name");
     public static final String CPU = System.getProperty("os.arch");
@@ -187,7 +188,7 @@ public abstract class TestC {
         }
 
         // Run GCC to link (optionally compile C driver code)
-        exec(10,params.asAry());
+        exec(TEST_TIMEOUT_SECONDS,params.asAry());
     }
 
     public static String exec( String... args ) throws IOException {
@@ -229,9 +230,11 @@ public abstract class TestC {
             if( stdin==null )
                 p.getOutputStream().close();
             if( seconds>0 && !p.waitFor(seconds,TimeUnit.SECONDS) ) {
+                String process = "pid="+p.pid()+", cpu="+
+                    p.info().totalCpuDuration().map(Object::toString).orElse("unknown");
                 p.destroyForcibly();
                 boolean stopped = p.waitFor(5,TimeUnit.SECONDS);
-                throw new IOException(String.join(" ",args)+"\ntimed out after "+seconds+" seconds"+
+                throw new IOException(String.join(" ",args)+"\ntimed out after "+seconds+" seconds ("+process+")"+
                                       (stopped ? "" : "; process did not terminate")+
                                       "\nstdout:\n"+Files.readString(stdoutFile)+
                                       "\nstderr:\n"+Files.readString(stderrFile));
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter20Test-testCast.smp b/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter20Test-testCast.smp
index 19c36ebb..d1368767 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter20Test-testCast.smp
+++ b/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter20Test-testCast.smp
@@ -1 +1 @@
-struct Bar { int x; }; var b = arg ? new Bar;  return b ? b.x++ + b.x++ : -1;
+struct _Bar { int x; }; var b = arg ? new _Bar;  return b ? b.x++ + b.x++ : -1;
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter20Test-testMergeSort.smp b/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter20Test-testMergeSort.smp
index eddf1799..417eba72 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter20Test-testMergeSort.smp
+++ b/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter20Test-testMergeSort.smp
@@ -1,21 +1,21 @@
 // based on the top-down version from https://en.wikipedia.org/wiki/Merge_sort
 
-val merge_sort = { int[] a, int[] b, int n ->
-    copy_array(a, 0, n, b);
-    split_merge(a, 0, n, b);
+val _merge_sort = { int[] a, int[] b, int n ->
+    _copy_array(a, 0, n, b);
+    _split_merge(a, 0, n, b);
 };
 
-val split_merge = { int[] b, int begin, int end, int[] a ->
+val _split_merge = { int[] b, int begin, int end, int[] a ->
     if (end - begin <= 1)
         return 0;
     int middle = (end + begin) / 2;
-    split_merge(a, begin, middle, b);
-    split_merge(a, middle, end, b);
-    merge(b, begin, middle, end, a);
+    _split_merge(a, begin, middle, b);
+    _split_merge(a, middle, end, b);
+    _merge(b, begin, middle, end, a);
     return 0;
 };
 
-val merge = { int[] b, int begin, int middle, int end, int[] a ->
+val _merge = { int[] b, int begin, int middle, int end, int[] a ->
     int i = begin, j = middle;
 
     for (int k = begin; k < end; k++) {
@@ -30,7 +30,7 @@ val merge = { int[] b, int begin, int middle, int end, int[] a ->
     }
 };
 
-val copy_array = { int[] a, int begin, int end, int[] b ->
+val _copy_array = { int[] a, int begin, int end, int[] b ->
     for (int k = begin; k < end; k++)
         b[k] = a[k];
 };
@@ -41,6 +41,6 @@ int[] !b = new int[a#];
 for (int i = 0; i < a#; i++)
     a[i] = a# - i;
 
-merge_sort(a, b, a#);
+_merge_sort(a, b, a#);
 
 return a;
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter20Test-testNewtonFloat.smp b/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter20Test-testNewtonFloat.smp
index 7fa66a33..fd76478f 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter20Test-testNewtonFloat.smp
+++ b/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter20Test-testNewtonFloat.smp
@@ -1,5 +1,5 @@
 // Newtons approximation to the square root
-val sqrt = { flt x ->
+val _sqrt = { flt x ->
     flt guess = x;
     while( 1 ) {
         flt next = (x/guess + guess)/2;
@@ -8,4 +8,4 @@ val sqrt = { flt x ->
     }
 };
 flt farg = arg;
-return sqrt(farg) + sqrt(farg+2.0);
+return _sqrt(farg) + _sqrt(farg+2.0);
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter20Test-testNewtonInteger.smp b/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter20Test-testNewtonInteger.smp
index b97da1f3..8912dcd9 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter20Test-testNewtonInteger.smp
+++ b/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter20Test-testNewtonInteger.smp
@@ -1,5 +1,5 @@
 // Newtons approximation to the square root
-val sqrt = { int x ->
+val _sqrt = { int x ->
     int guess = x;
     while( 1 ) {
         int next = (x/guess + guess)/2;
@@ -7,4 +7,4 @@ val sqrt = { int x ->
         guess = next;
     }
 };
-return sqrt(arg) + sqrt(arg+2);
+return _sqrt(arg) + _sqrt(arg+2);
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter20Test-testString.smp b/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter20Test-testString.smp
index f66ad621..951cdc32 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter20Test-testString.smp
+++ b/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter20Test-testString.smp
@@ -1,10 +1,10 @@
-struct String {
+struct _String {
     u8[] cs;
-    new String={ u8[] b -> cs=b; };
+    new _String={ u8[] b -> cs=b; };
     int _hashCode;
 };
 
-val equals = { !String !self, !String s ->
+val _equals = { !_String !self, !_String s ->
     if( self == s ) return true;
     if( self.cs# != s.cs# ) return false;
     for( int i=0; i< self.cs#; i++ )
@@ -13,13 +13,13 @@ val equals = { !String !self, !String s ->
     return true;
 };
 
-val hashCode = { !String self ->
+val _hashCode = { !_String self ->
     self._hashCode
     ?  self._hashCode
     : (self._hashCode = _hashCodeString(self));
 };
 
-val _hashCodeString = { !String self ->
+val _hashCodeString = { !_String self ->
     int hash=0;
     if( self.cs ) {
         for( int i=0; i< self.cs#; i++ )
@@ -29,7 +29,7 @@ val _hashCodeString = { !String self ->
     return hash;
 };
 
-!String !s = new String(new u8[17]);
+!_String !s = new _String(new u8[17]);
 s.cs[0] =  67; // C
 s.cs[1] = 108; // l
-hashCode(s);
+_hashCode(s);
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter21AllocTest-testNewtonFloat.smp b/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter21AllocTest-testNewtonFloat.smp
index 2b1acfbe..58449f9c 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter21AllocTest-testNewtonFloat.smp
+++ b/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter21AllocTest-testNewtonFloat.smp
@@ -1,6 +1,6 @@
 // -*- mode: java;  -*-
 // Newtons approximation to the square root
-val test_sqrt = { flt x ->
+val _test_sqrt = { flt x ->
     flt epsilon = 1e-15;
     flt guess = x;
     while( 1 ) {
@@ -10,4 +10,4 @@ val test_sqrt = { flt x ->
         guess = next;
     }
 };
-flt farg = arg; return test_sqrt(farg) + test_sqrt(farg+2.0);
+flt farg = arg; return _test_sqrt(farg) + _test_sqrt(farg+2.0);
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter22Test-testInfiniteReturn.smp b/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter22Test-testInfiniteReturn.smp
index f9866025..cc549808 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter22Test-testInfiniteReturn.smp
+++ b/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter22Test-testInfiniteReturn.smp
@@ -1 +1 @@
-struct S { int i; }; !S !s = new S; while(1) s.i++; return s.i;
+struct _S { int i; }; !_S !s = new _S; while(1) s.i++; return s.i;
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter22Test-testNarrowCReturns.smp b/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter22Test-testNarrowCReturns.smp
new file mode 100644
index 00000000..21293a7a
--- /dev/null
+++ b/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter22Test-testNarrowCReturns.smp
@@ -0,0 +1,12 @@
+{i8} c_i8="C"; {u8} c_u8="C";
+{i16} c_i16="C"; {u16} c_u16="C";
+{i32} c_i32="C"; {u32} c_u32="C";
+{int} c_i64="C";
+val test_i8={->return c_i8();};
+val test_u8={->return c_u8();};
+val test_i16={->return c_i16();};
+val test_u16={->return c_u16();};
+val test_i32={->return c_i32();};
+val test_u32={->return c_u32();};
+val test_i64={->return c_i64();};
+val test_cmp={->return c_i32()==-1;};
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter22Test-testSextFail.smp b/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter22Test-testSextFail.smp
index 9558bca4..ec9c6d50 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter22Test-testSextFail.smp
+++ b/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter22Test-testSextFail.smp
@@ -1,4 +1,4 @@
-struct Person { i32 age;};
-!Person !p = new Person;
+struct _Person { i32 age;};
+!_Person !p = new _Person;
 p.age = (arg<<17)>>17;
 return 0;
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter22Test-testSextFail2.smp b/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter22Test-testSextFail2.smp
index d3a27319..d5264aa2 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter22Test-testSextFail2.smp
+++ b/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter22Test-testSextFail2.smp
@@ -1,5 +1,5 @@
 
-        struct Person { i32 age;};
-        !Person !p = new Person;
+        struct _Person { i32 age;};
+        !_Person !p = new _Person;
         p.age = (arg<<48)>>48;
         return 0;
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter22Test-testSextSuccess.smp b/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter22Test-testSextSuccess.smp
index fdf4a7e9..c4398a89 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter22Test-testSextSuccess.smp
+++ b/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter22Test-testSextSuccess.smp
@@ -1,5 +1,5 @@
 // Should fold away sign extend
-struct Person { i8 age;};
-!Person !p = new Person;
+struct _Person { i8 age;};
+!_Person !p = new _Person;
 p.age = (arg<<48)>>48;
 return 0;
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter23AllocTest-testJig21.smp b/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter23AllocTest-testJig21.smp
deleted file mode 100644
index f7a5d202..00000000
--- a/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter23AllocTest-testJig21.smp
+++ /dev/null
@@ -1,16 +0,0 @@
-// -*- mode: java;  -*-
-val fib = {int n ->
-    int temp=0;
-    int f1=1;
-    int f2=1;
-    int i=n;
-    while( i>1 ){
-        temp = f1+f2;
-        f1=f2;
-        f2=temp;
-        i=i-1;
-    }
-    return f2;
-};
-
-fib(10);
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter24AllocTest-testJig21.smp b/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter24AllocTest-testJig21.smp
deleted file mode 100644
index f09915a1..00000000
--- a/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter24AllocTest-testJig21.smp
+++ /dev/null
@@ -1,16 +0,0 @@
-struct s0 {
-    bool v1;
-    i16 v2;
-    int v3;
-    i8 v4;
-    byte v5;
-};
-while(new s0.v3)
-    while(new s0.v5<<new s0.v4) {}
-if(0) {
-    if(0) {
-        flt !P5ZUD4=new s0.v2;
-    }
-    while(0) {}
-}
-return new s0.v1;
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter24AllocTest-testJig22.smp b/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter24AllocTest-testJig22.smp
deleted file mode 100644
index df605c94..00000000
--- a/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter24AllocTest-testJig22.smp
+++ /dev/null
@@ -1,15 +0,0 @@
-val fib = {int n ->
-    int temp=0;
-    int f1=1;
-    int f2=1;
-    int i=n;
-    while( i>1 ){
-        temp = f1+f2;
-        f1=f2;
-        f2=temp;
-        i=i-1;
-    }
-    return f2;
-};
-
-fib(10);
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter24AllocTest-testNewtonInteger.smp b/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter24AllocTest-testNewtonInteger.smp
index 0423585b..572e4ad7 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter24AllocTest-testNewtonInteger.smp
+++ b/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter24AllocTest-testNewtonInteger.smp
@@ -1,5 +1,5 @@
 // Newtons approximation to the square root
-val sqrt = { int x ->
+val _sqrt = { int x ->
     int guess = x;
     while( 1 ) {
         int next = (x/guess + guess)/2;
@@ -8,4 +8,4 @@ val sqrt = { int x ->
     }
 };
 int cast_int = arg+2;
-return sqrt(arg) + sqrt(cast_int);
+return _sqrt(arg) + _sqrt(cast_int);
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter24Test-testJig.smp b/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter24Test-testJig.smp
deleted file mode 100644
index 5c9d3aa5..00000000
--- a/chapter25/src/test/java/com/seaofnodes/simple/spill/Chapter24Test-testJig.smp
+++ /dev/null
@@ -1 +0,0 @@
-int v0=0;  v0 = arg && 0== 0 !=0;
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/spill/README.md b/chapter25/src/test/java/com/seaofnodes/simple/spill/README.md
index 3a064486..08371ae9 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/spill/README.md
+++ b/chapter25/src/test/java/com/seaofnodes/simple/spill/README.md
@@ -2,15 +2,23 @@
 
 English | [日本語](README.ja.md)
 
-`cohorts.tsv` freezes the 212 compilation entries measured by Chapter 24's
-`SpillStats`: 39, 52, 24, 30, and 67 entries for cohorts 20-24. The source files
+`cohorts.tsv` freezes 199 compilation entries matching Chapter 24's
+`SpillStats`: 39, 52, 26, 24, and 58 entries for cohorts 20-24. The source files
 are deduplicated by contents and named for their first referring test. The
 manifest preserves test identity, target, ABI, and the original stopping phase.
 `Win64` becomes `win64`, the Chapter 25 ABI spelling. Argument type is i64 and
 the replay seed is 123 throughout.
 
-These inputs were captured from the Chapter 24 tests before this final audit's
-new correctness regressions. They are a stable comparison corpus; changing one
+The original 212 entries were captured from the Chapter 24 tests before the
+allocator audit's new correctness regressions. The 2026-10-07 refresh adds
+Chapter22Test.testNarrowCReturns on x86 SystemV and Win64, matching the two
+entries already measured in Chapters 22-24. The source is unchanged; only the
+manifest's ABI spelling changes. The [cross-chapter matrix](../../../../../../../../docs/regalloc-spills.md)
+checks matching test/CPU/ABI membership, including repeated compilations.
+The same refresh removes all 15 Jig entries: six from cohort 23 and nine from
+cohort 24. Jig methods are ignored scratch pads for debugging, not regression
+tests or allocation benchmarks. Their frozen source copies were removed too.
+These inputs are a stable comparison corpus; changing one
 requires explaining the resulting break in comparability. Synthetic allocator
 and instruction regressions do not contribute allocations to these cohorts.
 
@@ -32,7 +40,17 @@ Chapter 25 cannot parse all earlier sources unchanged. Adaptations are explicit:
   Bubble Sort includes the old library bodies, with namespace prefixes flattened,
   explicit constructors, and mutable replacement buffers. This retains the old
   workload instead of substituting Chapter 25's substantially revised example.
-- Other source texts, including both original Newton float variants, are retained.
+- Local implementation names are private in eleven fixtures: the four Newton
+  variants that call their helper from the top level, Chapter 20's MergeSort,
+  String and Cast programs, and Chapter 22's three sign-extension programs and
+  InfiniteReturn. Their helpers/classes acquire an underscore prefix; operations,
+  inputs and final results are unchanged. This avoids exporting implementation
+  functions and allocation factories solely because Chapter 25 treats top-level
+  declarations as module members. Export/API fixtures, including NewtonExport,
+  StringExport, Person and the C-return wrappers, retain their public names.
+  These visibility adaptations change the generated workload and are recorded
+  separately from the allocator improvement in the cross-chapter comparison.
+- Other source texts are retained.
 
 All entries replay **through RegAlloc**, checking scheduled register constraints.
 The historical phase column is provenance, not a promise to run those old native
diff --git a/chapter25/src/test/java/com/seaofnodes/simple/spill/cohorts.tsv b/chapter25/src/test/java/com/seaofnodes/simple/spill/cohorts.tsv
index e1643e39..83b19d2a 100644
--- a/chapter25/src/test/java/com/seaofnodes/simple/spill/cohorts.tsv
+++ b/chapter25/src/test/java/com/seaofnodes/simple/spill/cohorts.tsv
@@ -129,21 +129,12 @@ Chapter23	Chapter23Test.testCondSideEffOr	arm	SystemV	Export	Chapter23Test-testC
 Chapter23	Chapter23Test.testFuncCall	x86_64_v2	win64	Export	Chapter23Test-testFuncCall.smp
 Chapter23	Chapter23Test.testFuncCall	riscv	SystemV	Export	Chapter23Test-testFuncCall.smp
 Chapter23	Chapter23Test.testFuncCall	arm	SystemV	Export	Chapter23Test-testFuncCall.smp
-Chapter23	Chapter23AllocTest.testJig21	x86_64_v2	win64	Encoding	Chapter23AllocTest-testJig21.smp
-Chapter23	Chapter23AllocTest.testJig21	riscv	SystemV	Encoding	Chapter23AllocTest-testJig21.smp
-Chapter23	Chapter23AllocTest.testJig21	arm	SystemV	Encoding	Chapter23AllocTest-testJig21.smp
-Chapter23	Chapter23AllocTest.testJig22	x86_64_v2	win64	Encoding	Chapter23AllocTest-testJig21.smp
-Chapter23	Chapter23AllocTest.testJig22	riscv	SystemV	Encoding	Chapter23AllocTest-testJig21.smp
-Chapter23	Chapter23AllocTest.testJig22	arm	SystemV	Encoding	Chapter23AllocTest-testJig21.smp
 Chapter23	Chapter23AllocTest.testString	x86_64_v2	SystemV	Encoding	Chapter23AllocTest-testString.smp
 Chapter23	Chapter23AllocTest.testString	riscv	SystemV	Encoding	Chapter23AllocTest-testString.smp
 Chapter23	Chapter23AllocTest.testString	arm	SystemV	Encoding	Chapter23AllocTest-testString.smp
 Chapter24	Chapter24Test.testAnd	x86_64_v2	win64	Export	Chapter23Test-testAnd.smp
 Chapter24	Chapter24Test.testAnd	riscv	SystemV	Export	Chapter23Test-testAnd.smp
 Chapter24	Chapter24Test.testAnd	arm	SystemV	Export	Chapter23Test-testAnd.smp
-Chapter24	Chapter24Test.testJig	x86_64_v2	win64	Encoding	Chapter24Test-testJig.smp
-Chapter24	Chapter24Test.testJig	riscv	SystemV	Encoding	Chapter24Test-testJig.smp
-Chapter24	Chapter24Test.testJig	arm	SystemV	Encoding	Chapter24Test-testJig.smp
 Chapter24	Chapter24Test.testOr	x86_64_v2	win64	Export	Chapter23Test-testOr.smp
 Chapter24	Chapter24Test.testOr	riscv	SystemV	Export	Chapter23Test-testOr.smp
 Chapter24	Chapter24Test.testOr	arm	SystemV	Export	Chapter23Test-testOr.smp
@@ -193,12 +184,6 @@ Chapter24	Chapter24Test.testFuncCall	arm	SystemV	Export	Chapter23Test-testFuncCa
 Chapter24	Chapter24AllocTest.testNewtonInteger	x86_64_v2	win64	Encoding	Chapter24AllocTest-testNewtonInteger.smp
 Chapter24	Chapter24AllocTest.testNewtonInteger	riscv	SystemV	Encoding	Chapter24AllocTest-testNewtonInteger.smp
 Chapter24	Chapter24AllocTest.testNewtonInteger	arm	SystemV	Encoding	Chapter24AllocTest-testNewtonInteger.smp
-Chapter24	Chapter24AllocTest.testJig21	x86_64_v2	win64	Encoding	Chapter24AllocTest-testJig21.smp
-Chapter24	Chapter24AllocTest.testJig21	riscv	SystemV	Encoding	Chapter24AllocTest-testJig21.smp
-Chapter24	Chapter24AllocTest.testJig21	arm	SystemV	Encoding	Chapter24AllocTest-testJig21.smp
-Chapter24	Chapter24AllocTest.testJig22	x86_64_v2	win64	Encoding	Chapter24AllocTest-testJig22.smp
-Chapter24	Chapter24AllocTest.testJig22	riscv	SystemV	Encoding	Chapter24AllocTest-testJig22.smp
-Chapter24	Chapter24AllocTest.testJig22	arm	SystemV	Encoding	Chapter24AllocTest-testJig22.smp
 Chapter24	Chapter24AllocTest.testStackArguments	x86_64_v2	win64	Export	Chapter24AllocTest-testStackArguments.smp
 Chapter24	Chapter24AllocTest.testStackArguments	riscv	SystemV	Export	Chapter24AllocTest-testStackArguments.smp
 Chapter24	Chapter24AllocTest.testStackArguments	arm	SystemV	Export	Chapter24AllocTest-testStackArguments.smp
@@ -211,3 +196,5 @@ Chapter21	BrainFuckTest.testBrainFuck	arm	SystemV	Export	BrainFuckTest-testBrain
 Chapter21	MergeSortTest.testMergeSort0	x86_64_v2	win64	Export	MergeSortTest-testMergeSort0.smp
 Chapter21	MergeSortTest.testMergeSort0	riscv	SystemV	Export	MergeSortTest-testMergeSort0.smp
 Chapter21	MergeSortTest.testMergeSort0	arm	SystemV	Encoding	MergeSortTest-testMergeSort0.smp
+Chapter22	Chapter22Test.testNarrowCReturns	x86_64_v2	SystemV	Export	Chapter22Test-testNarrowCReturns.smp
+Chapter22	Chapter22Test.testNarrowCReturns	x86_64_v2	win64	Export	Chapter22Test-testNarrowCReturns.smp