[3.13] gh-119821: Support non-dict globals in LOAD_FROM_DICT_OR_GLOBALS (#119822) (#119889)

dSupport non-dict globals in LOAD_FROM_DICT_OR_GLOBALS

The implementation basically copies LOAD_GLOBAL. Possibly it could be deduplicated,
but that seems like it may get hairy since the two operations have different operands.

This is important to fix in 3.14 for PEP 649, but it's a bug in earlier versions too,
and we should backport to 3.13 and 3.12 if possible.

(cherry picked from commit 80a4e3899420faaa012c82b4e82cdb6675a6a944)

4 files changed, 54 insertions, 54 deletions

diff --git a/Python/bytecodes.c b/Python/bytecodes.c
index 8a6222c..0dc60bb 100644
--- a/Python/bytecodes.c
+++ b/Python/bytecodes.c
@@ -1375,18 +1375,35 @@ dummy_func(
                 ERROR_NO_POP();
             }
             if (v == NULL) {
-                if (PyDict_GetItemRef(GLOBALS(), name, &v) < 0) {
-                    ERROR_NO_POP();
-                }
-                if (v == NULL) {
-                    if (PyMapping_GetOptionalItem(BUILTINS(), name, &v) < 0) {
+                if (PyDict_CheckExact(GLOBALS())
+                    && PyDict_CheckExact(BUILTINS()))
+                {
+                    v = _PyDict_LoadGlobal((PyDictObject *)GLOBALS(),
+                                            (PyDictObject *)BUILTINS(),
+                                            name);
+                    if (v == NULL) {
+                        if (!_PyErr_Occurred(tstate)) {
+                            /* _PyDict_LoadGlobal() returns NULL without raising
+                            * an exception if the key doesn't exist */
+                            _PyEval_FormatExcCheckArg(tstate, PyExc_NameError,
+                                                    NAME_ERROR_MSG, name);
+                        }
                         ERROR_NO_POP();
                     }
+                }
+                else {
+                    /* Slow-path if globals or builtins is not a dict */
+                    /* namespace 1: globals */
+                    ERROR_IF(PyMapping_GetOptionalItem(GLOBALS(), name, &v) < 0, error);
                     if (v == NULL) {
-                        _PyEval_FormatExcCheckArg(
-                                    tstate, PyExc_NameError,
-                                    NAME_ERROR_MSG, name);
-                        ERROR_NO_POP();
+                        /* namespace 2: builtins */
+                        ERROR_IF(PyMapping_GetOptionalItem(BUILTINS(), name, &v) < 0, error);
+                        if (v == NULL) {
+                            _PyEval_FormatExcCheckArg(
+                                        tstate, PyExc_NameError,
+                                        NAME_ERROR_MSG, name);
+                            ERROR_IF(true, error);
+                        }
                     }
                 }
             }
diff --git a/Python/executor_cases.c.h b/Python/executor_cases.c.h
index 4699c8e..4e0f73f 100644
--- a/Python/executor_cases.c.h
+++ b/Python/executor_cases.c.h
@@ -1394,35 +1394,7 @@
             break;
         }
 
-        case _LOAD_FROM_DICT_OR_GLOBALS: {
-            PyObject *mod_or_class_dict;
-            PyObject *v;
-            oparg = CURRENT_OPARG();
-            mod_or_class_dict = stack_pointer[-1];
-            PyObject *name = GETITEM(FRAME_CO_NAMES, oparg);
-            if (PyMapping_GetOptionalItem(mod_or_class_dict, name, &v) < 0) {
-                JUMP_TO_ERROR();
-            }
-            if (v == NULL) {
-                if (PyDict_GetItemRef(GLOBALS(), name, &v) < 0) {
-                    JUMP_TO_ERROR();
-                }
-                if (v == NULL) {
-                    if (PyMapping_GetOptionalItem(BUILTINS(), name, &v) < 0) {
-                        JUMP_TO_ERROR();
-                    }
-                    if (v == NULL) {
-                        _PyEval_FormatExcCheckArg(
-                            tstate, PyExc_NameError,
-                            NAME_ERROR_MSG, name);
-                        JUMP_TO_ERROR();
-                    }
-                }
-            }
-            Py_DECREF(mod_or_class_dict);
-            stack_pointer[-1] = v;
-            break;
-        }
+        /* _LOAD_FROM_DICT_OR_GLOBALS is not a viable micro-op for tier 2 because it has both popping and not-popping errors */
 
         /* _LOAD_NAME is not a viable micro-op for tier 2 because it has both popping and not-popping errors */
 
diff --git a/Python/generated_cases.c.h b/Python/generated_cases.c.h
index 32d5b8b..ace91a3 100644
--- a/Python/generated_cases.c.h
+++ b/Python/generated_cases.c.h
@@ -4381,18 +4381,35 @@
                 goto error;
             }
             if (v == NULL) {
-                if (PyDict_GetItemRef(GLOBALS(), name, &v) < 0) {
-                    goto error;
-                }
-                if (v == NULL) {
-                    if (PyMapping_GetOptionalItem(BUILTINS(), name, &v) < 0) {
+                if (PyDict_CheckExact(GLOBALS())
+                    && PyDict_CheckExact(BUILTINS()))
+                {
+                    v = _PyDict_LoadGlobal((PyDictObject *)GLOBALS(),
+                        (PyDictObject *)BUILTINS(),
+                        name);
+                    if (v == NULL) {
+                        if (!_PyErr_Occurred(tstate)) {
+                            /* _PyDict_LoadGlobal() returns NULL without raising
+                             * an exception if the key doesn't exist */
+                            _PyEval_FormatExcCheckArg(tstate, PyExc_NameError,
+                                NAME_ERROR_MSG, name);
+                        }
                         goto error;
                     }
+                }
+                else {
+                    /* Slow-path if globals or builtins is not a dict */
+                    /* namespace 1: globals */
+                    if (PyMapping_GetOptionalItem(GLOBALS(), name, &v) < 0) goto pop_1_error;
                     if (v == NULL) {
-                        _PyEval_FormatExcCheckArg(
-                            tstate, PyExc_NameError,
-                            NAME_ERROR_MSG, name);
-                        goto error;
+                        /* namespace 2: builtins */
+                        if (PyMapping_GetOptionalItem(BUILTINS(), name, &v) < 0) goto pop_1_error;
+                        if (v == NULL) {
+                            _PyEval_FormatExcCheckArg(
+                                tstate, PyExc_NameError,
+                                NAME_ERROR_MSG, name);
+                            if (true) goto pop_1_error;
+                        }
                     }
                 }
             }
diff --git a/Python/optimizer_cases.c.h b/Python/optimizer_cases.c.h
index 2a4efd7..6c2480d 100644
--- a/Python/optimizer_cases.c.h
+++ b/Python/optimizer_cases.c.h
@@ -815,13 +815,7 @@
             break;
         }
 
-        case _LOAD_FROM_DICT_OR_GLOBALS: {
-            _Py_UopsSymbol *v;
-            v = sym_new_not_null(ctx);
-            if (v == NULL) goto out_of_space;
-            stack_pointer[-1] = v;
-            break;
-        }
+        /* _LOAD_FROM_DICT_OR_GLOBALS is not a viable micro-op for tier 2 */
 
         /* _LOAD_NAME is not a viable micro-op for tier 2 */