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gh-123497: New limit for Python integers on 64-bit platforms (GH-123724)

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Instead of be limited just by the size of addressable memory (2**63
bytes), Python integers are now also limited by the number of bits, so
the number of bit now always fit in a 64-bit integer.

Both limits are much larger than what might be available in practice,
so it doesn't affect users.

_PyLong_NumBits() and _PyLong_Frexp() are now always successful.
This commit is contained in:
Serhiy Storchaka 2024-09-29 10:40:20 +03:00 • committed by GitHub
parent e0a41a5dd1
commit d08c788822
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GPG key ID: B5690EEEBB952194
8 changed files with 108 additions and 175 deletions
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23
Python/ast_opt.c
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@ -169,11 +169,10 @@ safe_multiply(PyObject *v, PyObject *w)
if (PyLong_Check(v) && PyLong_Check(w) &&
!_PyLong_IsZero((PyLongObject *)v) && !_PyLong_IsZero((PyLongObject *)w)
) {
uint64_t vbits = _PyLong_NumBits(v);
uint64_t wbits = _PyLong_NumBits(w);
if (vbits == (uint64_t)-1 || wbits == (uint64_t)-1) {
return NULL;
}
int64_t vbits = _PyLong_NumBits(v);
int64_t wbits = _PyLong_NumBits(w);
assert(vbits >= 0);
assert(wbits >= 0);
if (vbits + wbits > MAX_INT_SIZE) {
return NULL;
}
@ -215,12 +214,13 @@ safe_power(PyObject *v, PyObject *w)
if (PyLong_Check(v) && PyLong_Check(w) &&
!_PyLong_IsZero((PyLongObject *)v) && _PyLong_IsPositive((PyLongObject *)w)
) {
uint64_t vbits = _PyLong_NumBits(v);
int64_t vbits = _PyLong_NumBits(v);
size_t wbits = PyLong_AsSize_t(w);
if (vbits == (uint64_t)-1 || wbits == (size_t)-1) {
assert(vbits >= 0);
if (wbits == (size_t)-1) {
return NULL;
}
if (vbits > MAX_INT_SIZE / wbits) {
if ((uint64_t)vbits > MAX_INT_SIZE / wbits) {
return NULL;
}
}
@ -234,12 +234,13 @@ safe_lshift(PyObject *v, PyObject *w)
if (PyLong_Check(v) && PyLong_Check(w) &&
!_PyLong_IsZero((PyLongObject *)v) && !_PyLong_IsZero((PyLongObject *)w)
) {
uint64_t vbits = _PyLong_NumBits(v);
int64_t vbits = _PyLong_NumBits(v);
size_t wbits = PyLong_AsSize_t(w);
if (vbits == (uint64_t)-1 || wbits == (size_t)-1) {
assert(vbits >= 0);
if (wbits == (size_t)-1) {
return NULL;
}
if (wbits > MAX_INT_SIZE || vbits > MAX_INT_SIZE - wbits) {
if (wbits > MAX_INT_SIZE || (uint64_t)vbits > MAX_INT_SIZE - wbits) {
return NULL;
}
}