bpo-37986: Improve perfomance of PyLong_FromDouble() (GH-15611)
* bpo-37986: Improve perfomance of PyLong_FromDouble()
* Use strict bound check for safety and symmetry
* Remove possibly outdated performance claims
Co-authored-by: Mark Dickinson <dickinsm@gmail.com>
diff --git a/Objects/floatobject.c b/Objects/floatobject.c
index faa02f2..9f50140 100644
--- a/Objects/floatobject.c
+++ b/Objects/floatobject.c
@@ -862,27 +862,7 @@
float___trunc___impl(PyObject *self)
/*[clinic end generated code: output=dd3e289dd4c6b538 input=591b9ba0d650fdff]*/
{
- double x = PyFloat_AsDouble(self);
- double wholepart; /* integral portion of x, rounded toward 0 */
-
- (void)modf(x, &wholepart);
- /* Try to get out cheap if this fits in a Python int. The attempt
- * to cast to long must be protected, as C doesn't define what
- * happens if the double is too big to fit in a long. Some rare
- * systems raise an exception then (RISCOS was mentioned as one,
- * and someone using a non-default option on Sun also bumped into
- * that). Note that checking for >= and <= LONG_{MIN,MAX} would
- * still be vulnerable: if a long has more bits of precision than
- * a double, casting MIN/MAX to double may yield an approximation,
- * and if that's rounded up, then, e.g., wholepart=LONG_MAX+1 would
- * yield true from the C expression wholepart<=LONG_MAX, despite
- * that wholepart is actually greater than LONG_MAX.
- */
- if (LONG_MIN < wholepart && wholepart < LONG_MAX) {
- const long aslong = (long)wholepart;
- return PyLong_FromLong(aslong);
- }
- return PyLong_FromDouble(wholepart);
+ return PyLong_FromDouble(PyFloat_AS_DOUBLE(self));
}
/*[clinic input]