From 628d94039c38f9d13df661da66df69943ccb2061 Mon Sep 17 00:00:00 2001
From: Cliff Click <cliffc@acm.org>
Date: Sat, 19 Sep 2026 14:41:56 -0700
Subject: Handle r/w <clinit> sections

---
 .../src/main/java/com/seaofnodes/simple/codegen/ElfWriter.java   | 3 +--
 .../src/main/java/com/seaofnodes/simple/codegen/Encoding.java    | 9 +++++++--
 .../src/main/java/com/seaofnodes/simple/codegen/LinkMem.java     | 3 +--
 .../src/main/java/com/seaofnodes/simple/print/ASMPrinter.java    | 3 +--
 4 files changed, 10 insertions(+), 8 deletions(-)

(limited to 'chapter25/src/main/java/com')

diff --git a/chapter25/src/main/java/com/seaofnodes/simple/codegen/ElfWriter.java b/chapter25/src/main/java/com/seaofnodes/simple/codegen/ElfWriter.java
index 7af7e5f1..a74303e6 100644
--- a/chapter25/src/main/java/com/seaofnodes/simple/codegen/ElfWriter.java
+++ b/chapter25/src/main/java/com/seaofnodes/simple/codegen/ElfWriter.java
@@ -319,8 +319,7 @@ public class ElfWriter {
         // Write relocations for the constant pool
         String cpoolPrefix = _code.entryClinitName().replaceAll("[^A-Za-z0-9_$]", "_") + "$CPOOL$";
         for( Encoding.Relo relo : enc._bigCons.values() ) {
-            boolean ro = !(relo._t instanceof TypeStruct ts) || ts.isConstant();
-            DataSection data = ro ? rodata : rwdata;
+            DataSection data = relo.readOnly() ? rodata : rwdata;
             int symidx = symbols.symbol(cpoolPrefix+symbols.gidx(), data._index, SYM_BIND_GLOBAL, SYM_TYPE_FUNC, relo._target, relo._t.size());
             relocations.writeReloOffPlus(relo._opStart+relo._off, symidx, relo._elf );
         }
diff --git a/chapter25/src/main/java/com/seaofnodes/simple/codegen/Encoding.java b/chapter25/src/main/java/com/seaofnodes/simple/codegen/Encoding.java
index 4c7475fd..48ca4335 100644
--- a/chapter25/src/main/java/com/seaofnodes/simple/codegen/Encoding.java
+++ b/chapter25/src/main/java/com/seaofnodes/simple/codegen/Encoding.java
@@ -53,6 +53,12 @@ public class Encoding {
         Relo( Node op, Type t, byte off, byte elf ) {
             _op=op;  _t=t;  _off=off; _elf=elf;
         }
+        public boolean readOnly() {
+            // Class initializers still write their fields, even when every
+            // final value is constant.  Their storage must remain writable.
+            return !(_t instanceof TypeStruct ts) ||
+                (!Parser.startsClzPrefix(ts._name) && ts.isConstant());
+        }
     }
 
     Encoding( CodeGen code ) {
@@ -510,8 +516,7 @@ public class Encoding {
         Ary<Relo>[] raligns = new Ary[5];
         for( Node op : _bigCons.keySet() ) {
             Relo relo = _bigCons.get(op);
-            // non-constant structs in the r/w data, everything else in r/o data
-            if( (relo._t instanceof TypeStruct ts && !ts.isConstant()) == ro )
+            if( relo.readOnly() != ro )
                 continue;
             int align = relo._t.alignment();
             Ary<Relo> relos = raligns[align]==null ? (raligns[align]=new Ary<>(Relo.class)) : raligns[align];
diff --git a/chapter25/src/main/java/com/seaofnodes/simple/codegen/LinkMem.java b/chapter25/src/main/java/com/seaofnodes/simple/codegen/LinkMem.java
index e0b59395..d249b80c 100644
--- a/chapter25/src/main/java/com/seaofnodes/simple/codegen/LinkMem.java
+++ b/chapter25/src/main/java/com/seaofnodes/simple/codegen/LinkMem.java
@@ -23,8 +23,7 @@ public class LinkMem {
         // Patch local ops, e.g. loading float constants from the constant pool
         for( Node op : enc._bigCons.keySet() ) {
             Encoding.Relo relo = enc._bigCons.get(op);
-            boolean ro = !(relo._t instanceof TypeStruct ts) || ts.isConstant();
-            int target = relo._target+(ro ? cpool : sdata);
+            int target = relo._target+(relo.readOnly() ? cpool : sdata);
             ((RIPRelSize)relo._op).patch(enc, relo._opStart, enc.opLen(relo._op), target - relo._opStart);
         }
 
diff --git a/chapter25/src/main/java/com/seaofnodes/simple/print/ASMPrinter.java b/chapter25/src/main/java/com/seaofnodes/simple/print/ASMPrinter.java
index e15d7dbe..7f9f3ad9 100644
--- a/chapter25/src/main/java/com/seaofnodes/simple/print/ASMPrinter.java
+++ b/chapter25/src/main/java/com/seaofnodes/simple/print/ASMPrinter.java
@@ -45,8 +45,7 @@ public abstract class ASMPrinter {
         Ary<Relo>[] raligns = new Ary[5];
         for( Node op : bigCons.keySet() ) {
             Relo relo = bigCons.get(op);
-            // non-constant structs in the r/w data, everything else in r/o data
-            if( (relo._t instanceof TypeStruct ts && !ts.isConstant()) == ro )
+            if( relo.readOnly() != ro )
                 continue;
             int align = relo._t.alignment();
             Ary<Relo> relos = raligns[align]==null ? (raligns[align]=new Ary<>( Relo.class)) : raligns[align];
-- 
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