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Move hidden-class lock initialisation earlier. #430

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Merged
davidchisnall merged 1 commit into from
Oct 13, 2026
+5 −6
Merged

Move hidden-class lock initialisation earlier. #430

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11 changes: 5 additions & 6 deletions associate.mm
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Original file line number Diff line number Diff line change
Expand Up @@ -216,6 +216,11 @@ static Class allocateHiddenClass(Class superclass)
newClass->dtable = uninstalled_dtable;
newClass->instance_size = superclass->instance_size;

// Initialise the lock *before* this is globally reachable via any path.
// This would ideally belong in `initHiddenClassForObject`, but it's also
// possible to find the class after this point by traversing the class
// hierarchy and paths after that may attempt to acquire the lock.
INIT_LOCK(static_cast<struct reference_list*>(object_getIndexedIvars(reinterpret_cast<id>(newClass)))->lock);
LOCK_RUNTIME_FOR_SCOPE();
newClass->sibling_class = superclass->subclass_list;
superclass->subclass_list = (Class)newClass;
Expand Down Expand Up @@ -308,8 +313,6 @@ static void deallocHiddenClass(id obj, SEL _cmd)
if (NULL == hiddenClass)
{
hiddenClass = initHiddenClassForObject(object);
struct reference_list *list = static_cast<struct reference_list *>(object_getIndexedIvars(hiddenClass));
INIT_LOCK(list->lock);
}
}
return hiddenClass ? static_cast<struct reference_list*>(object_getIndexedIvars(hiddenClass)) : nullptr;
Expand Down Expand Up @@ -419,8 +422,6 @@ static Class hiddenClassForObject(id object)
if (NULL == hiddenClass)
{
hiddenClass = initHiddenClassForObject(object);
struct reference_list *list = static_cast<struct reference_list*>(object_getIndexedIvars(hiddenClass));
INIT_LOCK(list->lock);
}
}
return hiddenClass;
Expand All @@ -445,8 +446,6 @@ id object_clone_np(id object)
referenceListForObject(object, YES);
id newInstance = class_createInstance(object->isa, 0);
Class hiddenClass = initHiddenClassForObject(newInstance);
struct reference_list *list = static_cast<struct reference_list*>(object_getIndexedIvars(hiddenClass));
INIT_LOCK(list->lock);
objc_setAssociatedObject(newInstance, &prototypeKey, object,
OBJC_ASSOCIATION_RETAIN_NONATOMIC);
return newInstance;
Expand Down
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