diff options
Diffstat (limited to 'Objects')
| -rw-r--r-- | Objects/longobject.c | 79 |
1 files changed, 79 insertions, 0 deletions
diff --git a/Objects/longobject.c b/Objects/longobject.c index f3afb10..3f9837f 100644 --- a/Objects/longobject.c +++ b/Objects/longobject.c @@ -3502,6 +3502,52 @@ long_mul(PyLongObject *a, PyLongObject *b) return (PyObject *)z; } +/* Fast modulo division for single-digit longs. */ +static PyObject * +fast_mod(PyLongObject *a, PyLongObject *b) +{ + sdigit left = a->ob_digit[0]; + sdigit right = b->ob_digit[0]; + sdigit mod; + + assert(Py_ABS(Py_SIZE(a)) == 1); + assert(Py_ABS(Py_SIZE(b)) == 1); + + if (Py_SIZE(a) == Py_SIZE(b)) { + /* 'a' and 'b' have the same sign. */ + mod = left % right; + } + else { + /* Either 'a' or 'b' is negative. */ + mod = right - 1 - (left - 1) % right; + } + + return PyLong_FromLong(mod * Py_SIZE(b)); +} + +/* Fast floor division for single-digit longs. */ +static PyObject * +fast_floor_div(PyLongObject *a, PyLongObject *b) +{ + sdigit left = a->ob_digit[0]; + sdigit right = b->ob_digit[0]; + sdigit div; + + assert(Py_ABS(Py_SIZE(a)) == 1); + assert(Py_ABS(Py_SIZE(b)) == 1); + + if (Py_SIZE(a) == Py_SIZE(b)) { + /* 'a' and 'b' have the same sign. */ + div = left / right; + } + else { + /* Either 'a' or 'b' is negative. */ + div = -1 - (left - 1) / right; + } + + return PyLong_FromLong(div); +} + /* The / and % operators are now defined in terms of divmod(). The expression a mod b has the value a - b*floor(a/b). The long_divrem function gives the remainder after division of @@ -3529,6 +3575,30 @@ l_divmod(PyLongObject *v, PyLongObject *w, { PyLongObject *div, *mod; + if (Py_ABS(Py_SIZE(v)) == 1 && Py_ABS(Py_SIZE(w)) == 1) { + /* Fast path for single-digit longs */ + div = NULL; + if (pdiv != NULL) { + div = (PyLongObject *)fast_floor_div(v, w); + if (div == NULL) { + return -1; + } + } + if (pmod != NULL) { + mod = (PyLongObject *)fast_mod(v, w); + if (mod == NULL) { + Py_XDECREF(div); + return -1; + } + *pmod = mod; + } + if (pdiv != NULL) { + /* We only want to set `*pdiv` when `*pmod` is + set successfully. */ + *pdiv = div; + } + return 0; + } if (long_divrem(v, w, &div, &mod) < 0) return -1; if ((Py_SIZE(mod) < 0 && Py_SIZE(w) > 0) || @@ -3573,6 +3643,11 @@ long_div(PyObject *a, PyObject *b) PyLongObject *div; CHECK_BINOP(a, b); + + if (Py_ABS(Py_SIZE(a)) == 1 && Py_ABS(Py_SIZE(b)) == 1) { + return fast_floor_div((PyLongObject*)a, (PyLongObject*)b); + } + if (l_divmod((PyLongObject*)a, (PyLongObject*)b, &div, NULL) < 0) div = NULL; return (PyObject *)div; @@ -3848,6 +3923,10 @@ long_mod(PyObject *a, PyObject *b) CHECK_BINOP(a, b); + if (Py_ABS(Py_SIZE(a)) == 1 && Py_ABS(Py_SIZE(b)) == 1) { + return fast_mod((PyLongObject*)a, (PyLongObject*)b); + } + if (l_divmod((PyLongObject*)a, (PyLongObject*)b, NULL, &mod) < 0) mod = NULL; return (PyObject *)mod; |