4 files changed, 41 insertions, 20 deletions

diff --git a/Objects/codeobject.c b/Objects/codeobject.c
index 148350c..eb8de13 100644
--- a/Objects/codeobject.c
+++ b/Objects/codeobject.c
@@ -1867,14 +1867,11 @@ free_monitoring_data(_PyCoMonitoringData *data)
 static void
 code_dealloc(PyCodeObject *co)
 {
-    assert(Py_REFCNT(co) == 0);
-    Py_SET_REFCNT(co, 1);
+    _PyObject_ResurrectStart((PyObject *)co);
     notify_code_watchers(PY_CODE_EVENT_DESTROY, co);
-    if (Py_REFCNT(co) > 1) {
-        Py_SET_REFCNT(co, Py_REFCNT(co) - 1);
+    if (_PyObject_ResurrectEnd((PyObject *)co)) {
         return;
     }
-    Py_SET_REFCNT(co, 0);
 
 #ifdef Py_GIL_DISABLED
     PyObject_GC_UnTrack(co);
diff --git a/Objects/dictobject.c b/Objects/dictobject.c
index a13d808..1c9f864 100644
--- a/Objects/dictobject.c
+++ b/Objects/dictobject.c
@@ -3162,14 +3162,11 @@ dict_dealloc(PyObject *self)
 {
     PyDictObject *mp = (PyDictObject *)self;
     PyInterpreterState *interp = _PyInterpreterState_GET();
-    assert(Py_REFCNT(mp) == 0);
-    Py_SET_REFCNT(mp, 1);
+    _PyObject_ResurrectStart(self);
     _PyDict_NotifyEvent(interp, PyDict_EVENT_DEALLOCATED, mp, NULL, NULL);
-    if (Py_REFCNT(mp) > 1) {
-        Py_SET_REFCNT(mp, Py_REFCNT(mp) - 1);
+    if (_PyObject_ResurrectEnd(self)) {
         return;
     }
-    Py_SET_REFCNT(mp, 0);
     PyDictValues *values = mp->ma_values;
     PyDictKeysObject *keys = mp->ma_keys;
     Py_ssize_t i, n;
diff --git a/Objects/funcobject.c b/Objects/funcobject.c
index 4ba4728..cca7f01 100644
--- a/Objects/funcobject.c
+++ b/Objects/funcobject.c
@@ -1092,14 +1092,11 @@ static void
 func_dealloc(PyObject *self)
 {
     PyFunctionObject *op = _PyFunction_CAST(self);
-    assert(Py_REFCNT(op) == 0);
-    Py_SET_REFCNT(op, 1);
+    _PyObject_ResurrectStart(self);
     handle_func_event(PyFunction_EVENT_DESTROY, op, NULL);
-    if (Py_REFCNT(op) > 1) {
-        Py_SET_REFCNT(op, Py_REFCNT(op) - 1);
+    if (_PyObject_ResurrectEnd(self)) {
         return;
     }
-    Py_SET_REFCNT(op, 0);
     _PyObject_GC_UNTRACK(op);
     if (op->func_weakreflist != NULL) {
         PyObject_ClearWeakRefs((PyObject *) op);
diff --git a/Objects/object.c b/Objects/object.c
index 8868fa2..74f47fa 100644
--- a/Objects/object.c
+++ b/Objects/object.c
@@ -362,8 +362,10 @@ is_dead(PyObject *o)
 }
 # endif
 
-void
-_Py_DecRefSharedDebug(PyObject *o, const char *filename, int lineno)
+// Decrement the shared reference count of an object. Return 1 if the object
+// is dead and should be deallocated, 0 otherwise.
+static int
+_Py_DecRefSharedIsDead(PyObject *o, const char *filename, int lineno)
 {
     // Should we queue the object for the owning thread to merge?
     int should_queue;
@@ -404,6 +406,15 @@ _Py_DecRefSharedDebug(PyObject *o, const char *filename, int lineno)
     }
     else if (new_shared == _Py_REF_MERGED) {
         // refcount is zero AND merged
+        return 1;
+    }
+    return 0;
+}
+
+void
+_Py_DecRefSharedDebug(PyObject *o, const char *filename, int lineno)
+{
+    if (_Py_DecRefSharedIsDead(o, filename, lineno)) {
         _Py_Dealloc(o);
     }
 }
@@ -472,6 +483,26 @@ _Py_ExplicitMergeRefcount(PyObject *op, Py_ssize_t extra)
                                                 &shared, new_shared));
     return refcnt;
 }
+
+// The more complicated "slow" path for undoing the resurrection of an object.
+int
+_PyObject_ResurrectEndSlow(PyObject *op)
+{
+    if (_Py_IsImmortal(op)) {
+        return 1;
+    }
+    if (_Py_IsOwnedByCurrentThread(op)) {
+        // If the object is owned by the current thread, give up ownership and
+        // merge the refcount. This isn't necessary in all cases, but it
+        // simplifies the implementation.
+        Py_ssize_t refcount = _Py_ExplicitMergeRefcount(op, -1);
+        return refcount != 0;
+    }
+    int is_dead = _Py_DecRefSharedIsDead(op, NULL, 0);
+    return !is_dead;
+}
+
+
 #endif  /* Py_GIL_DISABLED */
 
 
@@ -550,7 +581,7 @@ PyObject_CallFinalizerFromDealloc(PyObject *self)
     }
 
     /* Temporarily resurrect the object. */
-    Py_SET_REFCNT(self, 1);
+    _PyObject_ResurrectStart(self);
 
     PyObject_CallFinalizer(self);
 
@@ -560,8 +591,7 @@ PyObject_CallFinalizerFromDealloc(PyObject *self)
 
     /* Undo the temporary resurrection; can't use DECREF here, it would
      * cause a recursive call. */
-    Py_SET_REFCNT(self, Py_REFCNT(self) - 1);
-    if (Py_REFCNT(self) == 0) {
+    if (!_PyObject_ResurrectEnd(self)) {
         return 0;         /* this is the normal path out */
     }