Implement Write Barrier for `autoload_table_type`

It's just a decorated st_table, so we call `RB_OBJ_WRITTEN` after
inserting to it.

We also call `RB_OBJ_WRITTEN` on delete for completeness even though
it's a noop.

1 files changed, 16 insertions, 12 deletions

diff --git a/variable.c b/variable.c
index 26a00db7c4..1a417da08e 100644
--- a/variable.c
+++ b/variable.c
@@ -2099,7 +2099,7 @@ autoload_table_compact(void *ptr)
 static const rb_data_type_t autoload_table_type = {
     "autoload_table",
     {autoload_table_mark, autoload_table_free, autoload_table_memsize, autoload_table_compact,},
-    0, 0, RUBY_TYPED_FREE_IMMEDIATELY
+    0, 0, RUBY_TYPED_FREE_IMMEDIATELY | RUBY_TYPED_WB_PROTECTED
 };
 
 #define check_autoload_table(av) \
@@ -2126,8 +2126,8 @@ autoload_data(VALUE mod, ID id)
 
     // Look up the instance variable table for `autoload`, then index into that table with the given constant name `id`.
 
-    VALUE tbl_value = rb_ivar_lookup(mod, autoload, 0);
-    if (!tbl_value || !(tbl = check_autoload_table(tbl_value)) || !st_lookup(tbl, (st_data_t)id, &val)) {
+    VALUE tbl_value = rb_ivar_lookup(mod, autoload, Qfalse);
+    if (!RTEST(tbl_value) || !(tbl = check_autoload_table(tbl_value)) || !st_lookup(tbl, (st_data_t)id, &val)) {
         return 0;
     }
 
@@ -2323,17 +2323,18 @@ autoload_feature_lookup_or_create(VALUE feature, struct autoload_data **autoload
     return autoload_data_value;
 }
 
-static struct st_table *
+static VALUE
 autoload_table_lookup_or_create(VALUE module)
 {
-    VALUE autoload_table_value = rb_ivar_lookup(module, autoload, 0);
-    if (autoload_table_value) {
-        return check_autoload_table(autoload_table_value);
+    VALUE autoload_table_value = rb_ivar_lookup(module, autoload, Qfalse);
+    if (RTEST(autoload_table_value)) {
+        return autoload_table_value;
     }
     else {
-        autoload_table_value = TypedData_Wrap_Struct(0, &autoload_table_type, 0);
+        autoload_table_value = TypedData_Wrap_Struct(0, &autoload_table_type, NULL);
         rb_class_ivar_set(module, autoload, autoload_table_value);
-        return (DATA_PTR(autoload_table_value) = st_init_numtable());
+        RTYPEDDATA_DATA(autoload_table_value) = st_init_numtable();
+        return autoload_table_value;
     }
 }
 
@@ -2350,7 +2351,8 @@ autoload_synchronized(VALUE _arguments)
     // Reset any state associated with any previous constant:
     const_set(arguments->module, arguments->name, Qundef);
 
-    struct st_table *autoload_table = autoload_table_lookup_or_create(arguments->module);
+    VALUE autoload_table_value = autoload_table_lookup_or_create(arguments->module);
+    struct st_table *autoload_table = check_autoload_table(autoload_table_value);
 
     // Ensure the string is uniqued since we use an identity lookup:
     VALUE feature = rb_fstring(arguments->feature);
@@ -2368,6 +2370,7 @@ autoload_synchronized(VALUE _arguments)
         autoload_const->autoload_data_value = autoload_data_value;
         ccan_list_add_tail(&autoload_data->constants, &autoload_const->cnode);
         st_insert(autoload_table, (st_data_t)arguments->name, (st_data_t)autoload_const_value);
+        RB_OBJ_WRITTEN(autoload_table_value, Qundef, autoload_const_value);
     }
 
     return Qtrue;
@@ -2407,11 +2410,12 @@ autoload_delete(VALUE module, ID name)
 
     RUBY_ASSERT(RB_TYPE_P(module, T_CLASS) || RB_TYPE_P(module, T_MODULE));
 
-    VALUE table_value = rb_ivar_lookup(module, autoload, 0);
-    if (table_value) {
+    VALUE table_value = rb_ivar_lookup(module, autoload, Qfalse);
+    if (RTEST(table_value)) {
         struct st_table *table = check_autoload_table(table_value);
 
         st_delete(table, &key, &load);
+        RB_OBJ_WRITTEN(table_value, load, Qundef);
 
         /* Qfalse can indicate already deleted */
         if (load != Qfalse) {