diff options
| -rw-r--r-- | Objects/listobject.c | 30 |
1 files changed, 6 insertions, 24 deletions
diff --git a/Objects/listobject.c b/Objects/listobject.c index c630f179e2..c9e66044c7 100644 --- a/Objects/listobject.c +++ b/Objects/listobject.c @@ -2234,13 +2234,6 @@ list_richcompare(PyObject *v, PyObject *w, int op) return PyObject_RichCompare(vl->ob_item[i], wl->ob_item[i], op); } -/* empirically determined threshold for activating an optimisation - * in list_fill() - 100 seems close to optimum for current CPUs and - * compilers, as of December '03. - * see also comment in list_fill(). - */ -#define LISTFILL_OPT_THRESHOLD 100 - /* Adapted from newer code by Tim */ static int list_fill(PyListObject *result, PyObject *v) @@ -2255,23 +2248,12 @@ list_fill(PyListObject *result, PyObject *v) n = result->ob_size; - /* Special-case list(a_list), for speed: - * - if the source has 0 elements, there's nothing to copy. - * - if the source has more than a threshold number of elements - * slice assignment is a faster way of filling the target - * (the exact threshold is subject to empirical determination). - * Also special case any other zero length sequence, including - * subclasses of list, there being nothing to copy. - */ - if (PyList_CheckExact(v)) { - i = PyList_GET_SIZE(v); - if (i == 0) - return 0; - if (i > LISTFILL_OPT_THRESHOLD) - return list_ass_slice(result, 0, n, v); - } else - if (PySequence_Check(v) && PySequence_Size(v) == 0) - return 0; + /* Special-case list(a_list), for speed. */ + if (PyList_Check(v)) { + if (v == (PyObject *)result) + return 0; /* source is destination, we're done */ + return list_ass_slice(result, 0, n, v); + } /* Empty previous contents */ if (n != 0) { |