gh-144569: Avoid creating temporary objects in BINARY_SLICE for list, tuple, and unicode

Misc/NEWS.d/next/Core_and_Builtins/2026-02-08-13-14-00.gh-issue-144569.pjlJVe.rst

@@ -0,0 +1 @@
+Optimize ``BINARY_SLICE`` for list, tuple, and unicode by avoiding temporary ``slice`` object creation.

Python/bytecodes.c

@@ -866,19 +866,47 @@ dummy_func(
         }
 
         op(_BINARY_SLICE, (container, start, stop -- res)) {
-            PyObject *slice = _PyBuildSlice_ConsumeRefs(PyStackRef_AsPyObjectSteal(start),
-                                                        PyStackRef_AsPyObjectSteal(stop));
+            PyObject *container_o = PyStackRef_AsPyObjectBorrow(container);
+            PyObject *start_o = PyStackRef_AsPyObjectBorrow(start);
+            PyObject *stop_o = PyStackRef_AsPyObjectBorrow(stop);
             PyObject *res_o;
-            // Can't use ERROR_IF() here, because we haven't
-            // DECREF'ed container yet, and we still own slice.
-            if (slice == NULL) {
-                res_o = NULL;
+            if (PyList_CheckExact(container_o) ||
+                PyTuple_CheckExact(container_o) ||
+                PyUnicode_CheckExact(container_o))
+            {
+                Py_ssize_t len = PyUnicode_CheckExact(container_o)
+                    ? PyUnicode_GET_LENGTH(container_o)
+                    : Py_SIZE(container_o);
+                Py_ssize_t istart = 0, istop = PY_SSIZE_T_MAX;
+                if (!_PyEval_SliceIndex(start_o, &istart) ||
+                    !_PyEval_SliceIndex(stop_o, &istop))
+                {
+                    res_o = NULL;
+                }
+                else {
+                    PySlice_AdjustIndices(len, &istart, &istop, 1);
+                    if (PyList_CheckExact(container_o)) {
+                        res_o = PyList_GetSlice(container_o, istart, istop);
+                    }
+                    else if (PyTuple_CheckExact(container_o)) {
+                        res_o = PyTuple_GetSlice(container_o, istart, istop);
+                    }
+                    else {
+                        res_o = PyUnicode_Substring(container_o, istart, istop);
+                    }
+                }
             }
             else {
-                res_o = PyObject_GetItem(PyStackRef_AsPyObjectBorrow(container), slice);
-                Py_DECREF(slice);
+                PyObject *slice = PySlice_New(start_o, stop_o, NULL);
+                if (slice == NULL) {
+                    res_o = NULL;
+                }
+                else {
+                    res_o = PyObject_GetItem(container_o, slice);
+                    Py_DECREF(slice);
+                }
             }
-            PyStackRef_CLOSE(container);
+            DECREF_INPUTS();
             ERROR_IF(res_o == NULL);
             res = PyStackRef_FromPyObjectSteal(res_o);
         }