Restore _PyObject_GetMethod optimization to LOAD_ATTR

Author: markshannon

Include/internal/pycore_opcode_metadata.h

@@ -1138,8 +1138,8 @@ def func2():
             ('call', 'func2', sys.monitoring.MISSING),
             ('line', 'func2', 1),
             ('line', 'func2', 2),
-            ('call', 'append', 2),
-            ('C return', 'append', 2),
+            ('call', 'append', [2]),
+            ('C return', 'append', [2]),
             ('line', 'func2', 3),
             ('line', 'get_events', 11),
             ('call', 'set_events', 2)])
@@ -1434,8 +1434,8 @@ def func2():
         self.check_events(func2, recorders = LOCAL_RECORDERS, expected = [
             ('line', 'func2', 1),
             ('line', 'func2', 2),
-            ('call', 'append', 2),
-            ('C return', 'append', 2),
+            ('call', 'append', [2]),
+            ('C return', 'append', [2]),
             ('line', 'func2', 3)])
 
     def test_try_except(self):
@@ -1913,6 +1913,7 @@ def f():
         """)
 
         def get_expected(name, call_method, ns):
+            repr_arg = 0 if name == "int" else sys.monitoring.MISSING
             return [
                 ('line', 'get_events', 10),
                 ('call', 'f', sys.monitoring.MISSING),
@@ -1923,8 +1924,8 @@ def get_expected(name, call_method, ns):
                 ('C return', name, sys.monitoring.MISSING),
                 *(
                     [
-                        ('call', '__repr__', sys.monitoring.MISSING),
-                        ('C return', '__repr__', sys.monitoring.MISSING),
+                        ('call', '__repr__', repr_arg),
+                        ('C return', '__repr__', repr_arg),
                     ] if call_method else []
                 ),
                 ('line', 'get_events', 11),

Lib/test/test_monitoring.py

@@ -2155,19 +2155,48 @@ dummy_func(
             #endif  /* ENABLE_SPECIALIZATION_FT */
         }
 
-        op(_LOAD_ATTR, (owner -- attr)) {
+        op(_LOAD_ATTR, (owner -- attr, self_or_null[oparg&1])) {
             PyObject *name = GETITEM(FRAME_CO_NAMES, oparg >> 1);
-            PyObject *attr_o = PyObject_GetAttr(PyStackRef_AsPyObjectBorrow(owner), name);
-            DECREF_INPUTS();
-            ERROR_IF(attr_o == NULL, error);
+            PyObject *attr_o;
+            if (oparg & 1) {
+                /* Designed to work in tandem with CALL, pushes two values. */
+                attr_o = NULL;
+                int is_meth = _PyObject_GetMethod(PyStackRef_AsPyObjectBorrow(owner), name, &attr_o);
+                if (is_meth) {
+                    /* We can bypass temporary bound method object.
+                       meth is unbound method and obj is self.
+                       meth | self | arg1 | ... | argN
+                     */
+                    assert(attr_o != NULL);  // No errors on this branch
+                    self_or_null[0] = owner;  // Transfer ownership
+                    DEAD(owner);
+                }
+                else {
+                    /* meth is not an unbound method (but a regular attr, or
+                       something was returned by a descriptor protocol).  Set
+                       the second element of the stack to NULL, to signal
+                       CALL that it's not a method call.
+                       meth | NULL | arg1 | ... | argN
+                    */
+                    DECREF_INPUTS();
+                    ERROR_IF(attr_o == NULL, error);
+                    self_or_null[0] = PyStackRef_NULL;
+                }
+            }
+            else {
+                /* Classic, pushes one value. */
+                attr_o = PyObject_GetAttr(PyStackRef_AsPyObjectBorrow(owner), name);
+                DECREF_INPUTS();
+                ERROR_IF(attr_o == NULL, error);
+            }
             attr = PyStackRef_FromPyObjectSteal(attr_o);
         }
 
+
         macro(LOAD_ATTR) =
             _SPECIALIZE_LOAD_ATTR +
             unused/8 +
-            _LOAD_ATTR +
-            _PUSH_NULL_CONDITIONAL;
+            _LOAD_ATTR;
 
         op(_GUARD_TYPE_VERSION, (type_version/2, owner -- owner)) {
             PyTypeObject *tp = Py_TYPE(PyStackRef_AsPyObjectBorrow(owner));

Python/bytecodes.c

@@ -548,9 +548,12 @@ dummy_func(void) {
         null = sym_new_null(ctx);
     }
 
-    op(_LOAD_ATTR, (owner -- attr)) {
+    op(_LOAD_ATTR, (owner -- attr, self_or_null[oparg&1])) {
         (void)owner;
         attr = sym_new_not_null(ctx);
+        if (oparg &1) {
+            self_or_null[0] = sym_new_unknown(ctx);
+        }
     }
 
     op(_LOAD_ATTR_MODULE_FROM_KEYS, (index/1, owner, mod_keys -- attr)) {