WIP

Author: byroot

variable.c

@@ -1234,17 +1234,35 @@ rb_obj_fields_no_ractor_check(VALUE obj)
 }
 
 void
-rb_obj_set_fields(VALUE obj, VALUE fields_obj, ID field_name, VALUE original_fields_obj)
+rb_free_generic_ivar(VALUE obj)
 {
-    RUBY_ASSERT(IMEMO_TYPE_P(fields_obj, imemo_fields));
+    if (rb_obj_exivar_p(obj)) {
+        st_data_t key = (st_data_t)obj, value;
 
-    if (fields_obj != original_fields_obj) {
         RB_VM_LOCKING() {
-            st_table *tbl = generic_fields_tbl(obj, field_name, false);
-            st_insert(tbl, (st_data_t)obj, (st_data_t)fields_obj);
+            st_delete(generic_fields_tbl_no_ractor_check(obj), &key, &value);
         }
+    }
+}
+
+void
+rb_obj_set_fields(VALUE obj, VALUE fields_obj, ID field_name, VALUE original_fields_obj)
+{
+    RUBY_ASSERT(!fields_obj || IMEMO_TYPE_P(fields_obj, imemo_fields));
+    RUBY_ASSERT(!original_fields_obj || IMEMO_TYPE_P(original_fields_obj, imemo_fields));
+
+    if (fields_obj != original_fields_obj) {
+        if (fields_obj) {
+            RB_VM_LOCKING() {
+                st_table *tbl = generic_fields_tbl(obj, field_name, false);
+                st_insert(tbl, (st_data_t)obj, (st_data_t)fields_obj);
+            }
 
-        RB_OBJ_WRITTEN(obj, original_fields_obj, fields_obj);
+            RB_OBJ_WRITTEN(obj, original_fields_obj, fields_obj);
+        }
+        else {
+            rb_free_generic_ivar(obj);
+        }
 
         if (original_fields_obj) {
             // Clear root shape to avoid triggering cleanup such as free_object_id.
@@ -1257,23 +1275,11 @@ void
 rb_obj_replace_fields(VALUE obj, VALUE fields_obj, ID field_name)
 {
     RB_VM_LOCKING() {
-        VALUE original_fields_obj = rb_obj_fields(fields_obj, field_name);
+        VALUE original_fields_obj = rb_obj_fields(obj, field_name);
         rb_obj_set_fields(obj, fields_obj, field_name, original_fields_obj);
     }
 }
 
-void
-rb_free_generic_ivar(VALUE obj)
-{
-    if (rb_obj_exivar_p(obj)) {
-        st_data_t key = (st_data_t)obj, value;
-
-        RB_VM_LOCKING() {
-            st_delete(generic_fields_tbl_no_ractor_check(obj), &key, &value);
-        }
-    }
-}
-
 VALUE
 rb_obj_field_get(VALUE obj, shape_id_t target_shape_id)
 {