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| -rw-r--r-- | Misc/NEWS.d/next/Core and Builtins/2021-09-20-10-02-12.bpo-24076.ZFgFSj.rst | 1 | ||||
| -rw-r--r-- | Python/bltinmodule.c | 10 |
2 files changed, 10 insertions, 1 deletions
diff --git a/Misc/NEWS.d/next/Core and Builtins/2021-09-20-10-02-12.bpo-24076.ZFgFSj.rst b/Misc/NEWS.d/next/Core and Builtins/2021-09-20-10-02-12.bpo-24076.ZFgFSj.rst new file mode 100644 index 0000000..b680884 --- /dev/null +++ b/Misc/NEWS.d/next/Core and Builtins/2021-09-20-10-02-12.bpo-24076.ZFgFSj.rst @@ -0,0 +1 @@ +sum() was further optimised for summing up single digit integers. diff --git a/Python/bltinmodule.c b/Python/bltinmodule.c index 76c9f87..38bdfb2 100644 --- a/Python/bltinmodule.c +++ b/Python/bltinmodule.c @@ -2479,7 +2479,15 @@ builtin_sum_impl(PyObject *module, PyObject *iterable, PyObject *start) return PyLong_FromLong(i_result); } if (PyLong_CheckExact(item) || PyBool_Check(item)) { - long b = PyLong_AsLongAndOverflow(item, &overflow); + long b; + overflow = 0; + /* Single digits are common, fast, and cannot overflow on unpacking. */ + switch (Py_SIZE(item)) { + case -1: b = -(sdigit) ((PyLongObject*)item)->ob_digit[0]; break; + case 0: continue; + case 1: b = ((PyLongObject*)item)->ob_digit[0]; break; + default: b = PyLong_AsLongAndOverflow(item, &overflow); break; + } if (overflow == 0 && (i_result >= 0 ? (b <= LONG_MAX - i_result) : (b >= LONG_MIN - i_result))) |