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Commit a5119e7

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serhiy-storchakaserhiy-storchaka
authored
bpo-36957: Add _PyLong_Rshift() and _PyLong_Lshift(). (GH-13416)
1 parent 1d5bdef commit a5119e7
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4 files changed

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‎Include/longobject.h

Copy file name to clipboardExpand all lines: Include/longobject.h
+3Lines changed: 3 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -230,6 +230,9 @@ PyAPI_FUNC(PyObject *) _PyLong_GCD(PyObject *, PyObject *);
230230
#ifndef Py_LIMITED_API
231231
PyAPI_DATA(PyObject *) _PyLong_Zero;
232232
PyAPI_DATA(PyObject *) _PyLong_One;
233+
234+
PyAPI_FUNC(PyObject *) _PyLong_Rshift(PyObject *, size_t);
235+
PyAPI_FUNC(PyObject *) _PyLong_Lshift(PyObject *, size_t);
233236
#endif
234237

235238
#ifdef __cplusplus

‎Modules/mathmodule.c

Copy file name to clipboardExpand all lines: Modules/mathmodule.c
+7-23Lines changed: 7 additions & 23 deletions
Original file line numberDiff line numberDiff line change
@@ -1671,18 +1671,13 @@ math_isqrt(PyObject *module, PyObject *n)
16711671
}
16721672
d = 0;
16731673
while (--s >= 0) {
1674-
PyObject *q, *shift;
1674+
PyObject *q;
16751675
size_t e = d;
16761676

16771677
d = c >> s;
16781678

16791679
/* q = (n >> 2*c - e - d + 1) // a */
1680-
shift = PyLong_FromSize_t(2U*c - d - e + 1U);
1681-
if (shift == NULL) {
1682-
goto error;
1683-
}
1684-
q = PyNumber_Rshift(n, shift);
1685-
Py_DECREF(shift);
1680+
q = _PyLong_Rshift(n, 2U*c - d - e + 1U);
16861681
if (q == NULL) {
16871682
goto error;
16881683
}
@@ -1692,13 +1687,7 @@ math_isqrt(PyObject *module, PyObject *n)
16921687
}
16931688

16941689
/* a = (a << d - 1 - e) + q */
1695-
shift = PyLong_FromSize_t(d - 1U - e);
1696-
if (shift == NULL) {
1697-
Py_DECREF(q);
1698-
goto error;
1699-
}
1700-
Py_SETREF(a, PyNumber_Lshift(a, shift));
1701-
Py_DECREF(shift);
1690+
Py_SETREF(a, _PyLong_Lshift(a, d - 1U - e));
17021691
if (a == NULL) {
17031692
Py_DECREF(q);
17041693
goto error;
@@ -1939,9 +1928,9 @@ static PyObject *
19391928
math_factorial(PyObject *module, PyObject *arg)
19401929
/*[clinic end generated code: output=6686f26fae00e9ca input=6d1c8105c0d91fb4]*/
19411930
{
1942-
long x;
1931+
long x, two_valuation;
19431932
int overflow;
1944-
PyObject *result, *odd_part, *two_valuation, *pyint_form;
1933+
PyObject *result, *odd_part, *pyint_form;
19451934

19461935
if (PyFloat_Check(arg)) {
19471936
PyObject *lx;
@@ -1990,13 +1979,8 @@ math_factorial(PyObject *module, PyObject *arg)
19901979
odd_part = factorial_odd_part(x);
19911980
if (odd_part == NULL)
19921981
return NULL;
1993-
two_valuation = PyLong_FromLong(x - count_set_bits(x));
1994-
if (two_valuation == NULL) {
1995-
Py_DECREF(odd_part);
1996-
return NULL;
1997-
}
1998-
result = PyNumber_Lshift(odd_part, two_valuation);
1999-
Py_DECREF(two_valuation);
1982+
two_valuation = x - count_set_bits(x);
1983+
result = _PyLong_Lshift(odd_part, two_valuation);
20001984
Py_DECREF(odd_part);
20011985
return result;
20021986
}

‎Objects/floatobject.c

Copy file name to clipboardExpand all lines: Objects/floatobject.c
+2-2Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -463,13 +463,13 @@ float_richcompare(PyObject *v, PyObject *w, int op)
463463
*/
464464
PyObject *temp;
465465

466-
temp = PyNumber_Lshift(ww, _PyLong_One);
466+
temp = _PyLong_Lshift(ww, 1);
467467
if (temp == NULL)
468468
goto Error;
469469
Py_DECREF(ww);
470470
ww = temp;
471471

472-
temp = PyNumber_Lshift(vv, _PyLong_One);
472+
temp = _PyLong_Lshift(vv, 1);
473473
if (temp == NULL)
474474
goto Error;
475475
Py_DECREF(vv);

‎Objects/longobject.c

Copy file name to clipboardExpand all lines: Objects/longobject.c
+75-28Lines changed: 75 additions & 28 deletions
Original file line numberDiff line numberDiff line change
@@ -4416,9 +4416,9 @@ long_bool(PyLongObject *v)
44164416

44174417
/* wordshift, remshift = divmod(shiftby, PyLong_SHIFT) */
44184418
static int
4419-
divmod_shift(PyLongObject *shiftby, Py_ssize_t *wordshift, digit *remshift)
4419+
divmod_shift(PyObject *shiftby, Py_ssize_t *wordshift, digit *remshift)
44204420
{
4421-
assert(PyLong_Check((PyObject *)shiftby));
4421+
assert(PyLong_Check(shiftby));
44224422
assert(Py_SIZE(shiftby) >= 0);
44234423
Py_ssize_t lshiftby = PyLong_AsSsize_t((PyObject *)shiftby);
44244424
if (lshiftby >= 0) {
@@ -4430,7 +4430,7 @@ divmod_shift(PyLongObject *shiftby, Py_ssize_t *wordshift, digit *remshift)
44304430
be that PyLong_AsSsize_t raised an OverflowError. */
44314431
assert(PyErr_ExceptionMatches(PyExc_OverflowError));
44324432
PyErr_Clear();
4433-
PyLongObject *wordshift_obj = divrem1(shiftby, PyLong_SHIFT, remshift);
4433+
PyLongObject *wordshift_obj = divrem1((PyLongObject *)shiftby, PyLong_SHIFT, remshift);
44344434
if (wordshift_obj == NULL) {
44354435
return -1;
44364436
}
@@ -4448,47 +4448,37 @@ divmod_shift(PyLongObject *shiftby, Py_ssize_t *wordshift, digit *remshift)
44484448
}
44494449

44504450
static PyObject *
4451-
long_rshift(PyLongObject *a, PyLongObject *b)
4451+
long_rshift1(PyLongObject *a, Py_ssize_t wordshift, digit remshift)
44524452
{
44534453
PyLongObject *z = NULL;
4454-
Py_ssize_t newsize, wordshift, hishift, i, j;
4455-
digit loshift, lomask, himask;
4456-
4457-
CHECK_BINOP(a, b);
4458-
4459-
if (Py_SIZE(b) < 0) {
4460-
PyErr_SetString(PyExc_ValueError,
4461-
"negative shift count");
4462-
return NULL;
4463-
}
4454+
Py_ssize_t newsize, hishift, i, j;
4455+
digit lomask, himask;
44644456

44654457
if (Py_SIZE(a) < 0) {
44664458
/* Right shifting negative numbers is harder */
44674459
PyLongObject *a1, *a2;
44684460
a1 = (PyLongObject *) long_invert(a);
44694461
if (a1 == NULL)
44704462
return NULL;
4471-
a2 = (PyLongObject *) long_rshift(a1, b);
4463+
a2 = (PyLongObject *) long_rshift1(a1, wordshift, remshift);
44724464
Py_DECREF(a1);
44734465
if (a2 == NULL)
44744466
return NULL;
44754467
z = (PyLongObject *) long_invert(a2);
44764468
Py_DECREF(a2);
44774469
}
44784470
else {
4479-
if (divmod_shift(b, &wordshift, &loshift) < 0)
4480-
return NULL;
44814471
newsize = Py_SIZE(a) - wordshift;
44824472
if (newsize <= 0)
44834473
return PyLong_FromLong(0);
4484-
hishift = PyLong_SHIFT - loshift;
4474+
hishift = PyLong_SHIFT - remshift;
44854475
lomask = ((digit)1 << hishift) - 1;
44864476
himask = PyLong_MASK ^ lomask;
44874477
z = _PyLong_New(newsize);
44884478
if (z == NULL)
44894479
return NULL;
44904480
for (i = 0, j = wordshift; i < newsize; i++, j++) {
4491-
z->ob_digit[i] = (a->ob_digit[j] >> loshift) & lomask;
4481+
z->ob_digit[i] = (a->ob_digit[j] >> remshift) & lomask;
44924482
if (i+1 < newsize)
44934483
z->ob_digit[i] |= (a->ob_digit[j+1] << hishift) & himask;
44944484
}
@@ -4498,15 +4488,10 @@ long_rshift(PyLongObject *a, PyLongObject *b)
44984488
}
44994489

45004490
static PyObject *
4501-
long_lshift(PyObject *v, PyObject *w)
4491+
long_rshift(PyObject *a, PyObject *b)
45024492
{
4503-
/* This version due to Tim Peters */
4504-
PyLongObject *a = (PyLongObject*)v;
4505-
PyLongObject *b = (PyLongObject*)w;
4506-
PyLongObject *z = NULL;
4507-
Py_ssize_t oldsize, newsize, wordshift, i, j;
4493+
Py_ssize_t wordshift;
45084494
digit remshift;
4509-
twodigits accum;
45104495

45114496
CHECK_BINOP(a, b);
45124497

@@ -4517,9 +4502,35 @@ long_lshift(PyObject *v, PyObject *w)
45174502
if (Py_SIZE(a) == 0) {
45184503
return PyLong_FromLong(0);
45194504
}
4520-
45214505
if (divmod_shift(b, &wordshift, &remshift) < 0)
45224506
return NULL;
4507+
return long_rshift1((PyLongObject *)a, wordshift, remshift);
4508+
}
4509+
4510+
/* Return a >> shiftby. */
4511+
PyObject *
4512+
_PyLong_Rshift(PyObject *a, size_t shiftby)
4513+
{
4514+
Py_ssize_t wordshift;
4515+
digit remshift;
4516+
4517+
assert(PyLong_Check(a));
4518+
if (Py_SIZE(a) == 0) {
4519+
return PyLong_FromLong(0);
4520+
}
4521+
wordshift = shiftby / PyLong_SHIFT;
4522+
remshift = shiftby % PyLong_SHIFT;
4523+
return long_rshift1((PyLongObject *)a, wordshift, remshift);
4524+
}
4525+
4526+
static PyObject *
4527+
long_lshift1(PyLongObject *a, Py_ssize_t wordshift, digit remshift)
4528+
{
4529+
/* This version due to Tim Peters */
4530+
PyLongObject *z = NULL;
4531+
Py_ssize_t oldsize, newsize, i, j;
4532+
twodigits accum;
4533+
45234534
oldsize = Py_ABS(Py_SIZE(a));
45244535
newsize = oldsize + wordshift;
45254536
if (remshift)
@@ -4547,6 +4558,42 @@ long_lshift(PyObject *v, PyObject *w)
45474558
return (PyObject *) maybe_small_long(z);
45484559
}
45494560

4561+
static PyObject *
4562+
long_lshift(PyObject *a, PyObject *b)
4563+
{
4564+
Py_ssize_t wordshift;
4565+
digit remshift;
4566+
4567+
CHECK_BINOP(a, b);
4568+
4569+
if (Py_SIZE(b) < 0) {
4570+
PyErr_SetString(PyExc_ValueError, "negative shift count");
4571+
return NULL;
4572+
}
4573+
if (Py_SIZE(a) == 0) {
4574+
return PyLong_FromLong(0);
4575+
}
4576+
if (divmod_shift(b, &wordshift, &remshift) < 0)
4577+
return NULL;
4578+
return long_lshift1((PyLongObject *)a, wordshift, remshift);
4579+
}
4580+
4581+
/* Return a << shiftby. */
4582+
PyObject *
4583+
_PyLong_Lshift(PyObject *a, size_t shiftby)
4584+
{
4585+
Py_ssize_t wordshift;
4586+
digit remshift;
4587+
4588+
assert(PyLong_Check(a));
4589+
if (Py_SIZE(a) == 0) {
4590+
return PyLong_FromLong(0);
4591+
}
4592+
wordshift = shiftby / PyLong_SHIFT;
4593+
remshift = shiftby % PyLong_SHIFT;
4594+
return long_lshift1((PyLongObject *)a, wordshift, remshift);
4595+
}
4596+
45504597
/* Compute two's complement of digit vector a[0:m], writing result to
45514598
z[0:m]. The digit vector a need not be normalized, but should not
45524599
be entirely zero. a and z may point to the same digit vector. */
@@ -5552,7 +5599,7 @@ static PyNumberMethods long_as_number = {
55525599
(inquiry)long_bool, /*tp_bool*/
55535600
(unaryfunc)long_invert, /*nb_invert*/
55545601
long_lshift, /*nb_lshift*/
5555-
(binaryfunc)long_rshift, /*nb_rshift*/
5602+
long_rshift, /*nb_rshift*/
55565603
long_and, /*nb_and*/
55575604
long_xor, /*nb_xor*/
55585605
long_or, /*nb_or*/

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