bpo-47009: Let PRECALL_NO_KW_LIST_APPEND do its own POP_TOP (GH-32239)

sweeneyde · web-flow · commit 6c6e0408a663 · 2022-04-05T11:18:30.000+01:00
diff --git a/Python/ceval.c b/Python/ceval.c
@@ -5040,15 +5040,15 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, _PyInterpreterFrame *frame, int
             PyObject *list = SECOND();
             DEOPT_IF(!PyList_Check(list), PRECALL);
             STAT_INC(PRECALL, hit);
-            SKIP_CALL();
+            // PRECALL + CALL + POP_TOP
+            JUMPBY(INLINE_CACHE_ENTRIES_PRECALL + 1 + INLINE_CACHE_ENTRIES_CALL + 1);
+            assert(next_instr[-1] == POP_TOP);
             PyObject *arg = POP();
             if (_PyList_AppendTakeRef((PyListObject *)list, arg) < 0) {
                 goto error;
             }
+            STACK_SHRINK(2);
             Py_DECREF(list);
-            STACK_SHRINK(1);
-            Py_INCREF(Py_None);
-            SET_TOP(Py_None);
             Py_DECREF(callable);
             NOTRACE_DISPATCH();
         }
diff --git a/Python/specialize.c b/Python/specialize.c
@@ -1435,7 +1435,10 @@ specialize_method_descriptor(PyMethodDescrObject *descr, _Py_CODEUNIT *instr,
             }
             PyInterpreterState *interp = _PyInterpreterState_GET();
             PyObject *list_append = interp->callable_cache.list_append;
-            if ((PyObject *)descr == list_append && oparg == 1) {
+            _Py_CODEUNIT next = instr[INLINE_CACHE_ENTRIES_PRECALL + 1
+                                      + INLINE_CACHE_ENTRIES_CALL + 1];
+            bool pop = (_Py_OPCODE(next) == POP_TOP);
+            if ((PyObject *)descr == list_append && oparg == 1 && pop) {
                 _Py_SET_OPCODE(*instr, PRECALL_NO_KW_LIST_APPEND);
                 return 0;
             }

Original file line number	Diff line number	Diff line change
`@@ -1435,7 +1435,10 @@ specialize_method_descriptor(PyMethodDescrObject descr, _Py_CODEUNIT instr,`
`1435`	`1435`	`}`
`1436`	`1436`	`PyInterpreterState *interp = _PyInterpreterState_GET();`
`1437`	`1437`	`PyObject *list_append = interp->callable_cache.list_append;`
`1438`		`- if ((PyObject *)descr == list_append && oparg == 1) {`
	`1438`	`+ _Py_CODEUNIT next = instr[INLINE_CACHE_ENTRIES_PRECALL + 1`
	`1439`	`+ + INLINE_CACHE_ENTRIES_CALL + 1];`
	`1440`	`+ bool pop = (_Py_OPCODE(next) == POP_TOP);`
	`1441`	`+ if ((PyObject *)descr == list_append && oparg == 1 && pop) {`
`1439`	`1442`	`_Py_SET_OPCODE(*instr, PRECALL_NO_KW_LIST_APPEND);`
`1440`	`1443`	`return 0;`
`1441`	`1444`	`}`