gh-123358: Update LOAD_DEREF to use stackref and atomic incref

Author: corona10

Include/internal/pycore_cell.h

@@ -2,6 +2,7 @@
 #define Py_INTERNAL_CELL_H
 
 #include "pycore_critical_section.h"
+#include "pycore_object.h"
 
 #ifdef __cplusplus
 extern "C" {
@@ -19,7 +20,7 @@ PyCell_SwapTakeRef(PyCellObject *cell, PyObject *value)
     PyObject *old_value;
     Py_BEGIN_CRITICAL_SECTION(cell);
     old_value = cell->ob_ref;
-    cell->ob_ref = value;
+    FT_ATOMIC_STORE_PTR_RELEASE(cell->ob_ref, value);
     Py_END_CRITICAL_SECTION();
     return old_value;
 }
@@ -42,6 +43,28 @@ PyCell_GetRef(PyCellObject *cell)
     return res;
 }
 
+static inline
+_PyStackRef _PyCell_GetStackRef(PyCellObject *cell)
+{
+    PyObject *value;
+#ifdef Py_GIL_DISABLED
+    value = _Py_atomic_load_ptr(&cell->ob_ref);
+    if (value != NULL) {
+        if (_Py_IsImmortal(value) || _PyObject_HasDeferredRefcount(value)) {
+             return (_PyStackRef){ .bits = (uintptr_t)value | Py_TAG_DEFERRED };
+         }
+        if (_Py_TryIncrefFast(value)) {
+            return _PyStackRef_FromPyObjectSteal(value);
+        }
+    }
+#endif
+    value = PyCell_GetRef(cell);
+    if (value == NULL) {
+        return PyStackRef_NULL;
+    }
+    return PyStackRef_FromPyObjectSteal(value);
+}
+
 #ifdef __cplusplus
 }
 #endif

Include/internal/pycore_opcode_metadata.h

@@ -1811,12 +1811,11 @@ dummy_func(
 
         inst(LOAD_DEREF, ( -- value)) {
             PyCellObject *cell = (PyCellObject *)PyStackRef_AsPyObjectBorrow(GETLOCAL(oparg));
-            PyObject *value_o = PyCell_GetRef(cell);
-            if (value_o == NULL) {
+            value = _PyCell_GetStackRef(cell);
+            if (PyStackRef_IsNull(value)) {
                 _PyEval_FormatExcUnbound(tstate, _PyFrame_GetCode(frame), oparg);
                 ERROR_IF(true, error);
             }
-            value = PyStackRef_FromPyObjectSteal(value_o);
         }
 
         inst(STORE_DEREF, (v --)) {