bpo-45107: Make LOAD_METHOD_CLASS safer and faster, clean up comments (GH-28177)

* Improve comments

* Check cls is a type, remove dict calculation

1 files changed, 7 insertions, 8 deletions

diff --git a/Python/specialize.c b/Python/specialize.c
index 8e04c83..398524c 100644
--- a/Python/specialize.c
+++ b/Python/specialize.c
@@ -974,20 +974,19 @@ _Py_Specialize_LoadMethod(PyObject *owner, _Py_CODEUNIT *instr, PyObject *name,
         // Fall through.
     } // Else owner is maybe a builtin with no dict, or __slots__. Doesn't matter.
 
-    /* `descr` is borrowed. Just check tp_version_tag before accessing in case
-    *  it's deleted.  This is safe for methods (even inherited ones from super
-    *  classes!) as long as tp_version_tag is validated for two main reasons:
+    /* `descr` is borrowed. This is safe for methods (even inherited ones from
+    *  super classes!) as long as tp_version_tag is validated for two main reasons:
     *
     *  1. The class will always hold a reference to the method so it will
     *  usually not be GC-ed. Should it be deleted in Python, e.g.
     *  `del obj.meth`, tp_version_tag will be invalidated, because of reason 2.
     *
     *  2. The pre-existing type method cache (MCACHE) uses the same principles
-    *  of caching a borrowed descriptor. It does all the heavy lifting for us.
-    *  E.g. it invalidates on any MRO modification, on any type object
-    *  change along said MRO, etc. (see PyType_Modified usages in typeobject.c).
-    *  The type method cache has been working since Python 2.6 and it's
-    *  battle-tested.
+    *  of caching a borrowed descriptor. The MCACHE infrastructure does all the
+    *  heavy lifting for us. E.g. it invalidates tp_version_tag on any MRO
+    *  modification, on any type object change along said MRO, etc. (see
+    *  PyType_Modified usages in typeobject.c). The MCACHE has been
+    *  working since Python 2.6 and it's battle-tested.
     */
     cache2->obj = descr;
     cache1->dk_version_or_hint = keys_version;