From a7049b2ad5520f4f1558a5435e20791853a066ba Mon Sep 17 00:00:00 2001 From: Victor Stinner Date: Wed, 10 Jan 2024 02:01:07 +0100 Subject: [PATCH] gh-111139: Optimize math.gcd(int, int) Add a fast-path for the common case. Benchmark: python -m pyperf timeit \ -s 'import math; gcd=math.gcd; x=2*3; y=3*5' \ 'gcd(x,y)' Result: 1.07x faster (-3.4 ns) Mean +- std dev: 52.6 ns +- 4.0 ns -> 49.2 ns +- 0.4 ns: 1.07x faster --- Modules/mathmodule.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) diff --git a/Modules/mathmodule.c b/Modules/mathmodule.c index 6cd61e9ab75424..38406f2f3bc842 100644 --- a/Modules/mathmodule.c +++ b/Modules/mathmodule.c @@ -759,13 +759,20 @@ m_log10(double x) static PyObject * math_gcd(PyObject *module, PyObject * const *args, Py_ssize_t nargs) { - PyObject *res, *x; - Py_ssize_t i; + // Fast-path for the common case: avoid calling _PyNumber_Index() + // and the loop. + if (nargs == 2 + && PyLong_CheckExact(args[0]) + && PyLong_CheckExact(args[1])) + { + return _PyLong_GCD(args[0], args[1]); + } if (nargs == 0) { return PyLong_FromLong(0); } - res = PyNumber_Index(args[0]); + + PyObject *res = PyNumber_Index(args[0]); if (res == NULL) { return NULL; } @@ -775,8 +782,8 @@ math_gcd(PyObject *module, PyObject * const *args, Py_ssize_t nargs) } PyObject *one = _PyLong_GetOne(); // borrowed ref - for (i = 1; i < nargs; i++) { - x = _PyNumber_Index(args[i]); + for (Py_ssize_t i = 1; i < nargs; i++) { + PyObject *x = _PyNumber_Index(args[i]); if (x == NULL) { Py_DECREF(res); return NULL;