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bpo-42161: Add _PyLong_GetZero() and _PyLong_GetOne() #22993

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Merged
merged 1 commit into from
Oct 26, 2020
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bpo-42161: Add _PyLong_GetZero() and _PyLong_GetOne() #22993

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7 changes: 5 additions & 2 deletions Include/internal/pycore_interp.h
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Original file line number Diff line number Diff line change
Expand Up @@ -163,6 +163,11 @@ struct _Py_exc_state {
#define _PY_NSMALLPOSINTS 257
#define _PY_NSMALLNEGINTS 5

// _PyLong_GetZero() and _PyLong_GetOne() must always be available
#if _PY_NSMALLPOSINTS < 2
# error "_PY_NSMALLPOSINTS must be greater than 1"
#endif

// The PyInterpreterState typedef is in Include/pystate.h.
struct _is {

Expand Down Expand Up @@ -233,14 +238,12 @@ struct _is {

PyObject *audit_hooks;

#if _PY_NSMALLNEGINTS + _PY_NSMALLPOSINTS > 0
/* Small integers are preallocated in this array so that they
can be shared.
The integers that are preallocated are those in the range
-_PY_NSMALLNEGINTS (inclusive) to _PY_NSMALLPOSINTS (not inclusive).
*/
PyLongObject* small_ints[_PY_NSMALLNEGINTS + _PY_NSMALLPOSINTS];
#endif
struct _Py_bytes_state bytes;
struct _Py_unicode_state unicode;
struct _Py_float_state float_state;
Expand Down
43 changes: 43 additions & 0 deletions Include/internal/pycore_long.h
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@@ -0,0 +1,43 @@
#ifndef Py_INTERNAL_LONG_H
#define Py_INTERNAL_LONG_H
#ifdef __cplusplus
extern "C" {
#endif

#ifndef Py_BUILD_CORE
# error "this header requires Py_BUILD_CORE define"
#endif

#include "pycore_interp.h" // PyInterpreterState.small_ints
#include "pycore_pystate.h" // _PyThreadState_GET()

// Don't call this function but _PyLong_GetZero() and _PyLong_GetOne()
static inline PyObject* __PyLong_GetSmallInt_internal(int value)
{
PyThreadState *tstate = _PyThreadState_GET();
#ifdef Py_DEBUG
_Py_EnsureTstateNotNULL(tstate);
#endif
assert(-_PY_NSMALLNEGINTS <= value && value < _PY_NSMALLPOSINTS);
size_t index = _PY_NSMALLNEGINTS + value;
PyObject *obj = (PyObject*)tstate->interp->small_ints[index];
// _PyLong_GetZero() and _PyLong_GetOne() must not be called
// before _PyLong_Init() nor after _PyLong_Fini()
assert(obj != NULL);
return obj;
}

// Return a borrowed reference to the zero singleton.
// The function cannot return NULL.
static inline PyObject* _PyLong_GetZero(void)
{ return __PyLong_GetSmallInt_internal(0); }

// Return a borrowed reference to the one singleton.
// The function cannot return NULL.
static inline PyObject* _PyLong_GetOne(void)
{ return __PyLong_GetSmallInt_internal(1); }

#ifdef __cplusplus
}
#endif
#endif /* !Py_INTERNAL_LONG_H */
1 change: 1 addition & 0 deletions Makefile.pre.in
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Expand Up @@ -1117,6 +1117,7 @@ PYTHON_HEADERS= \
$(srcdir)/Include/internal/pycore_initconfig.h \
$(srcdir)/Include/internal/pycore_interp.h \
$(srcdir)/Include/internal/pycore_list.h \
$(srcdir)/Include/internal/pycore_long.h \
$(srcdir)/Include/internal/pycore_object.h \
$(srcdir)/Include/internal/pycore_pathconfig.h \
$(srcdir)/Include/internal/pycore_pyerrors.h \
Expand Down
37 changes: 14 additions & 23 deletions Objects/longobject.c
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,7 @@
#include "Python.h"
#include "pycore_bitutils.h" // _Py_popcount32()
#include "pycore_interp.h" // _PY_NSMALLPOSINTS
#include "pycore_long.h" // __PyLong_GetSmallInt_internal()
#include "pycore_object.h" // _PyObject_InitVar()
#include "pycore_pystate.h" // _Py_IsMainInterpreter()
#include "longintrepr.h"
Expand All @@ -19,8 +20,8 @@ class int "PyObject *" "&PyLong_Type"
[clinic start generated code]*/
/*[clinic end generated code: output=da39a3ee5e6b4b0d input=ec0275e3422a36e3]*/

#define NSMALLPOSINTS _PY_NSMALLPOSINTS
#define NSMALLNEGINTS _PY_NSMALLNEGINTS
#define NSMALLPOSINTS _PY_NSMALLPOSINTS

_Py_IDENTIFIER(little);
_Py_IDENTIFIER(big);
Expand All @@ -34,16 +35,14 @@ _Py_IDENTIFIER(big);
PyObject *_PyLong_Zero = NULL;
PyObject *_PyLong_One = NULL;

#if NSMALLNEGINTS + NSMALLPOSINTS > 0
#define IS_SMALL_INT(ival) (-NSMALLNEGINTS <= (ival) && (ival) < NSMALLPOSINTS)
#define IS_SMALL_UINT(ival) ((ival) < NSMALLPOSINTS)

static PyObject *
get_small_int(sdigit ival)
{
assert(IS_SMALL_INT(ival));
PyInterpreterState *interp = _PyInterpreterState_GET();
PyObject *v = (PyObject*)interp->small_ints[ival + NSMALLNEGINTS];
PyObject *v = __PyLong_GetSmallInt_internal(ival);
Py_INCREF(v);
return v;
}
Expand All @@ -60,12 +59,6 @@ maybe_small_long(PyLongObject *v)
}
return v;
}
#else
#define IS_SMALL_INT(ival) 0
#define IS_SMALL_UINT(ival) 0
#define get_small_int(ival) (Py_UNREACHABLE(), NULL)
#define maybe_small_long(val) (val)
#endif

/* If a freshly-allocated int is already shared, it must
be a small integer, so negating it must go to PyLong_FromLong */
Expand Down Expand Up @@ -2559,8 +2552,9 @@ long_divrem(PyLongObject *a, PyLongObject *b,
if (*prem == NULL) {
return -1;
}
Py_INCREF(_PyLong_Zero);
*pdiv = (PyLongObject*)_PyLong_Zero;
PyObject *zero = _PyLong_GetZero();
Py_INCREF(zero);
*pdiv = (PyLongObject*)zero;
return 0;
}
if (size_b == 1) {
Expand Down Expand Up @@ -3669,7 +3663,7 @@ l_divmod(PyLongObject *v, PyLongObject *w,
Py_DECREF(div);
return -1;
}
temp = (PyLongObject *) long_sub(div, (PyLongObject *)_PyLong_One);
temp = (PyLongObject *) long_sub(div, (PyLongObject *)_PyLong_GetOne());
if (temp == NULL) {
Py_DECREF(mod);
Py_DECREF(div);
Expand Down Expand Up @@ -4078,7 +4072,7 @@ long_invmod(PyLongObject *a, PyLongObject *n)

Py_DECREF(c);
Py_DECREF(n);
if (long_compare(a, (PyLongObject *)_PyLong_One)) {
if (long_compare(a, (PyLongObject *)_PyLong_GetOne())) {
/* a != 1; we don't have an inverse. */
Py_DECREF(a);
Py_DECREF(b);
Expand Down Expand Up @@ -4313,7 +4307,7 @@ long_invert(PyLongObject *v)
PyLongObject *x;
if (Py_ABS(Py_SIZE(v)) <=1)
return PyLong_FromLong(-(MEDIUM_VALUE(v)+1));
x = (PyLongObject *) long_add(v, (PyLongObject *)_PyLong_One);
x = (PyLongObject *) long_add(v, (PyLongObject *)_PyLong_GetOne());
if (x == NULL)
return NULL;
_PyLong_Negate(&x);
Expand Down Expand Up @@ -5105,7 +5099,8 @@ _PyLong_DivmodNear(PyObject *a, PyObject *b)

/* compare twice the remainder with the divisor, to see
if we need to adjust the quotient and remainder */
twice_rem = long_lshift((PyObject *)rem, _PyLong_One);
PyObject *one = _PyLong_GetOne(); // borrowed reference
twice_rem = long_lshift((PyObject *)rem, one);
if (twice_rem == NULL)
goto error;
if (quo_is_neg) {
Expand All @@ -5122,9 +5117,9 @@ _PyLong_DivmodNear(PyObject *a, PyObject *b)
if ((Py_SIZE(b) < 0 ? cmp < 0 : cmp > 0) || (cmp == 0 && quo_is_odd)) {
/* fix up quotient */
if (quo_is_neg)
temp = long_sub(quo, (PyLongObject *)_PyLong_One);
temp = long_sub(quo, (PyLongObject *)one);
else
temp = long_add(quo, (PyLongObject *)_PyLong_One);
temp = long_add(quo, (PyLongObject *)one);
Py_DECREF(quo);
quo = (PyLongObject *)temp;
if (quo == NULL)
Expand Down Expand Up @@ -5406,7 +5401,7 @@ int_as_integer_ratio_impl(PyObject *self)
if (numerator == NULL) {
return NULL;
}
ratio_tuple = PyTuple_Pack(2, numerator, _PyLong_One);
ratio_tuple = PyTuple_Pack(2, numerator, _PyLong_GetOne());
Py_DECREF(numerator);
return ratio_tuple;
}
Expand Down Expand Up @@ -5712,7 +5707,6 @@ PyLong_GetInfo(void)
int
_PyLong_Init(PyThreadState *tstate)
{
#if NSMALLNEGINTS + NSMALLPOSINTS > 0
for (Py_ssize_t i=0; i < NSMALLNEGINTS + NSMALLPOSINTS; i++) {
sdigit ival = (sdigit)i - NSMALLNEGINTS;
int size = (ival < 0) ? -1 : ((ival == 0) ? 0 : 1);
Expand All @@ -5727,7 +5721,6 @@ _PyLong_Init(PyThreadState *tstate)

tstate->interp->small_ints[i] = v;
}
#endif

if (_Py_IsMainInterpreter(tstate)) {
_PyLong_Zero = PyLong_FromLong(0);
Expand Down Expand Up @@ -5759,9 +5752,7 @@ _PyLong_Fini(PyThreadState *tstate)
Py_CLEAR(_PyLong_Zero);
}

#if NSMALLNEGINTS + NSMALLPOSINTS > 0
for (Py_ssize_t i = 0; i < NSMALLNEGINTS + NSMALLPOSINTS; i++) {
Py_CLEAR(tstate->interp->small_ints[i]);
}
#endif
}
1 change: 1 addition & 0 deletions PCbuild/pythoncore.vcxproj
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Expand Up @@ -185,6 +185,7 @@
<ClInclude Include="..\Include\internal\pycore_initconfig.h" />
<ClInclude Include="..\Include\internal\pycore_interp.h" />
<ClInclude Include="..\Include\internal\pycore_list.h" />
<ClInclude Include="..\Include\internal\pycore_long.h" />
<ClInclude Include="..\Include\internal\pycore_object.h" />
<ClInclude Include="..\Include\internal\pycore_pathconfig.h" />
<ClInclude Include="..\Include\internal\pycore_pyerrors.h" />
Expand Down
3 changes: 3 additions & 0 deletions PCbuild/pythoncore.vcxproj.filters
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Expand Up @@ -537,6 +537,9 @@
<ClInclude Include="..\Include\internal\pycore_list.h">
<Filter>Include\internal</Filter>
</ClInclude>
<ClInclude Include="..\Include\internal\pycore_long.h">
<Filter>Include\internal</Filter>
</ClInclude>
<ClInclude Include="..\Include\internal\pycore_object.h">
<Filter>Include\internal</Filter>
</ClInclude>
Expand Down