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gh-156145: Don't rely on errno for float pow and is_integer #156551

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gh-156145: Don't rely on errno for float pow and is_integer #156551

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19 changes: 3 additions & 16 deletions Include/internal/pycore_pymath.h
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Original file line number Diff line number Diff line change
Expand Up @@ -9,10 +9,9 @@ extern "C" {
#endif


/* _Py_ADJUST_ERANGE1(x)
* _Py_ADJUST_ERANGE2(x, y)
* Set errno to 0 before calling a libm function, and invoke one of these
* macros after, passing the function result(s) (_Py_ADJUST_ERANGE2 is useful
/* _Py_ADJUST_ERANGE2(x, y)
* Set errno to 0 before calling a libm function, and invoke this
* macro after, passing the function result(s) (_Py_ADJUST_ERANGE2 is useful
* for functions returning complex results). This makes two kinds of
* adjustments to errno: (A) If it looks like the platform libm set
* errno=ERANGE due to underflow, clear errno. (B) If it looks like the
Expand All @@ -30,18 +29,6 @@ extern "C" {
* if the returned result is a NaN, or if a C89 box returns HUGE_VAL
* in non-overflow cases.
*/
static inline void _Py_ADJUST_ERANGE1(double x)
{
if (errno == 0) {
if (x == INFINITY || x == -INFINITY) {
errno = ERANGE;
}
}
else if (errno == ERANGE && x == 0.0) {
errno = 0;
}
}

static inline void _Py_ADJUST_ERANGE2(double x, double y)
{
if (x == INFINITY || x == -INFINITY ||
Expand Down
21 changes: 4 additions & 17 deletions Objects/floatobject.c
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Original file line number Diff line number Diff line change
Expand Up @@ -785,18 +785,13 @@ float_pow(PyObject *v, PyObject *w, PyObject *z)
* positive and not equal to 1.0. We finally allow
* the platform pow to step in and do the rest.
*/
errno = 0;
ix = pow(iv, iw);
_Py_ADJUST_ERANGE1(ix);
if (negate_result)
ix = -ix;

if (errno != 0) {
/* We don't expect any errno value other than ERANGE, but
* the range of libm bugs appears unbounded.
*/
PyErr_SetFromErrno(errno == ERANGE ? PyExc_OverflowError :
PyExc_ValueError);
if (isinf(ix)) {
PyErr_SetString(PyExc_OverflowError,
"float exponentiation result out of range");
return NULL;
}
return PyFloat_FromDouble(ix);
Expand Down Expand Up @@ -836,20 +831,12 @@ float_is_integer_impl(PyObject *self)
/*[clinic end generated code: output=7112acf95a4d31ea input=311810d3f777e10d]*/
{
double x = PyFloat_AsDouble(self);
PyObject *o;

if (x == -1.0 && PyErr_Occurred())
return NULL;
if (!isfinite(x))
Py_RETURN_FALSE;
errno = 0;
o = (floor(x) == x) ? Py_True : Py_False;
if (errno != 0) {
PyErr_SetFromErrno(errno == ERANGE ? PyExc_OverflowError :
PyExc_ValueError);
return NULL;
}
return Py_NewRef(o);
return PyBool_FromLong(floor(x) == x);
}

/*[clinic input]
Expand Down
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