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gh-153144: Avoid checking errno for atan2 #153148

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gh-153144: Avoid checking errno for atan2 #153148

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6 changes: 1 addition & 5 deletions Modules/cmathmodule.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1004,12 +1004,8 @@ cmath_phase_impl(PyObject *module, Py_complex z)
{
double phi;

errno = 0;
phi = atan2(z.imag, z.real); /* should not cause any exception */
if (errno != 0)
return math_error();
else
return PyFloat_FromDouble(phi);
return PyFloat_FromDouble(phi);
}

/*[clinic input]
Expand Down
45 changes: 36 additions & 9 deletions Modules/mathmodule.c
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Expand Up @@ -916,7 +916,7 @@ is_error(double x, int raise_edom)
C89 but for which HUGE_VAL is not an infinity.

For the majority of one-argument functions these rules are enough
to ensure that Python's functions behave as specified in 'Annex F'
to ensure that Python's functions behave as specified in Annex F
of the C99 standard, with the 'invalid' and 'divide-by-zero'
floating-point exceptions mapping to Python's ValueError and the
'overflow' floating-point exception mapping to OverflowError.
Expand Down Expand Up @@ -1011,12 +1011,11 @@ math_1a(PyObject *arg, double (*func) (double), const char *err_msg)
The last rule is used to catch overflow on platforms which follow
C89 but for which HUGE_VAL is not an infinity.

For most two-argument functions (copysign, fmod, hypot, atan2)
these rules are enough to ensure that Python's functions behave as
specified in 'Annex F' of the C99 standard, with the 'invalid' and
'divide-by-zero' floating-point exceptions mapping to Python's
ValueError and the 'overflow' floating-point exception mapping to
OverflowError.
For most two-argument functions (copysign, fmod, hypot) these rules
are enough to ensure that Python's functions behave as specified in
Annex F of the C99 standard, with the 'invalid' and 'divide-by-zero'
floating-point exceptions mapping to Python's ValueError and the
'overflow' floating-point exception mapping to OverflowError.
*/

static PyObject *
Expand Down Expand Up @@ -1054,6 +1053,28 @@ math_2(PyObject *const *args, Py_ssize_t nargs,
return PyFloat_FromDouble(r);
}

/* variant of math_2, to be used when the function being wrapped is known NOT
to need error checking (i.e., no overflow, invalid, or divide-by-zero). */

static PyObject *
math_2ne(PyObject *const *args, Py_ssize_t nargs,
double (*func) (double, double), const char *funcname)
{
double x, y, r;
if (!_PyArg_CheckPositional(funcname, nargs, 2, 2))
return NULL;
x = PyFloat_AsDouble(args[0]);
if (x == -1.0 && PyErr_Occurred()) {
return NULL;
}
y = PyFloat_AsDouble(args[1]);
if (y == -1.0 && PyErr_Occurred()) {
return NULL;
}
r = (*func)(x, y);
return PyFloat_FromDouble(r);
}

#define FUNC1(funcname, func, can_overflow, docstring) \
static PyObject * math_##funcname(PyObject *self, PyObject *args) { \
return math_1(args, func, can_overflow, NULL); \
Expand Down Expand Up @@ -1084,6 +1105,12 @@ math_2(PyObject *const *args, Py_ssize_t nargs,
}\
PyDoc_STRVAR(math_##funcname##_doc, docstring);

#define FUNC2NE(funcname, func, docstring) \
static PyObject * math_##funcname(PyObject *self, PyObject *const *args, Py_ssize_t nargs) { \
return math_2ne(args, nargs, func, #funcname); \
}\
PyDoc_STRVAR(math_##funcname##_doc, docstring);

FUNC1D(acos, acos, 0,
"acos($module, x, /)\n--\n\n"
"Return the arc cosine (measured in radians) of x.\n\n"
Expand Down Expand Up @@ -1115,11 +1142,11 @@ FUNC1(atan, atan, 0,
"atan($module, x, /)\n--\n\n"
"Return the arc tangent (measured in radians) of x.\n\n"
"The result is between -pi/2 and pi/2.")
FUNC2(atan2, atan2,
FUNC2NE(atan2, atan2,
"atan2($module, y, x, /)\n--\n\n"
"Return the arc tangent (measured in radians) of y/x.\n\n"
"Unlike atan(y/x), the signs of both x and y are considered.")
FUNC2(atan2pi, m_atan2pi,
FUNC2NE(atan2pi, m_atan2pi,
"atan2pi($module, y, x, /)\n--\n\n"
"Return the arc tangent (measured in half-turns) of y/x.\n\n"
"Unlike atanpi(y/x), the signs of both x and y are considered.")
Expand Down
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