pythongh-102839: remove AC for math.log

skirpichev · skirpichev · commit bdbc875b0462 · 2023-03-21T05:39:08.000+03:00
Before:
$  ./python -m timeit -s 'from math import log' 'log(1.1)'
1000000 loops, best of 5: 344 nsec per loop
$ ./python -m timeit -s 'from math import log' 'log(1.1, 3.2)'
500000 loops, best of 5: 601 nsec per loop

After:
$  ./python -m timeit -s 'from math import log' 'log(1.1)'
2000000 loops, best of 5: 171 nsec per loop
$ ./python -m timeit -s 'from math import log' 'log(1.1, 3.2)'
1000000 loops, best of 5: 348 nsec per loop
diff --git a/Misc/NEWS.d/next/Library/2023-03-20-12-21-19.gh-issue-102839.RjRi12.rst b/Misc/NEWS.d/next/Library/2023-03-20-12-21-19.gh-issue-102839.RjRi12.rst
@@ -0,0 +1 @@
+Improve performance of :func:`math.log` arguments handling.
diff --git a/Modules/clinic/mathmodule.c.h b/Modules/clinic/mathmodule.c.h
diff --git a/Modules/mathmodule.c b/Modules/mathmodule.c
@@ -2284,33 +2284,20 @@ loghelper(PyObject* arg, double (*func)(double))
 }
 
 
-/*[clinic input]
-math.log
-
-    x:    object
-    [
-    base: object(c_default="NULL") = math.e
-    ]
-    /
-
-Return the logarithm of x to the given base.
-
-If the base not specified, returns the natural logarithm (base e) of x.
-[clinic start generated code]*/
-
 static PyObject *
-math_log_impl(PyObject *module, PyObject *x, int group_right_1,
-              PyObject *base)
-/*[clinic end generated code: output=7b5a39e526b73fc9 input=0f62d5726cbfebbd]*/
+math_log(PyObject *module, PyObject * const *args, Py_ssize_t nargs)
 {
     PyObject *num, *den;
     PyObject *ans;
 
-    num = loghelper(x, m_log);
-    if (num == NULL || base == NULL)
+    if (!_PyArg_CheckPositional("log", nargs, 1, 2))
+        return NULL;
+
+    num = loghelper(args[0], m_log);
+    if (num == NULL || nargs == 1)
         return num;
 
-    den = loghelper(base, m_log);
+    den = loghelper(args[1], m_log);
     if (den == NULL) {
         Py_DECREF(num);
         return NULL;
@@ -2322,6 +2309,10 @@ math_log_impl(PyObject *module, PyObject *x, int group_right_1,
     return ans;
 }
 
+PyDoc_STRVAR(math_log_doc,
+"log(x, [base=math.e])\n\
+Return the logarithm of x to the given base.\n\n\
+If the base not specified, returns the natural logarithm (base e) of x.");
 
 /*[clinic input]
 math.log2
@@ -4045,7 +4036,7 @@ static PyMethodDef math_methods[] = {
     {"lcm",             _PyCFunction_CAST(math_lcm),       METH_FASTCALL,  math_lcm_doc},
     MATH_LDEXP_METHODDEF
     {"lgamma",          math_lgamma,    METH_O,         math_lgamma_doc},
-    MATH_LOG_METHODDEF
+    {"log",             _PyCFunction_CAST(math_log),       METH_FASTCALL,  math_log_doc},
     {"log1p",           math_log1p,     METH_O,         math_log1p_doc},
     MATH_LOG10_METHODDEF
     MATH_LOG2_METHODDEF

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1 @@`
	`1`	+Improve performance of :func:`math.log` arguments handling.