On Wed, 17 Jun 2026 11:33:20 GMT, Andrew Dinn <[email protected]> wrote:
>> It is true that IntegerPolynomial::conditionalAssign() is not only for the
>> IntegerPolynomialP256 subclass, but it has a fixed set of permitted
>> subclasses, with the number of limbs in the set {5, 10, 14, 16, 19} as one
>> can infer from the comment at the beginning of this function. So the 0-check
>> is not necessary.
>
> Yes, the definition of Java class `IntegerPolynomial` does limit the possible
> subclasses. However, as I mentioned in my earlier comment, that list includes
> `IntegerPolynomialModBinP`
>
>
> public abstract sealed class IntegerPolynomial implements IntegerFieldModuloP
> permits IntegerPolynomial1305, IntegerPolynomial25519,
> IntegerPolynomial448, IntegerPolynomialP256,
> MontgomeryIntegerPolynomialP256, IntegerPolynomialP384,
> IntegerPolynomialP521, IntegerPolynomialModBinP, P256OrderField,
> P384OrderField, P521OrderField, Curve25519OrderField,
> Curve448OrderField {
>
>
> This specific subclass employs a limb count specified by a caller in the
> constructor
>
>
> public sealed class IntegerPolynomialModBinP extends IntegerPolynomial {
> ...
> public IntegerPolynomialModBinP(int bitsPerLimb,
> int numLimbs,
> int power,
> BigInteger subtrahend) {
> super(bitsPerLimb, numLimbs, 1,
> BigInteger.valueOf(2).pow(power).subtract(subtrahend));
>
>
> So, for this class it looks as if a user could specify numLimbs == 0 when
> creating an `IntegerPolynomialModBinP` and that same count will be passed on
> up to `IntegerPolynomial`.
>
> Now, that doesn't guarantee that any subsequent call to
> `IntegerPolynomial::mult` will end up being passed a zero length array but
> I'd like to be reassured why this won't happen.
0 as number of limbs doesn't make sense as no number can be represented that
way. I think the IntegerPolynomialModBinP class was created for testing
purposes mainly and only the two inner classes should subclass it, i.e. the
constructor should rather be private and in that case the 0 number of limbs
would not be a concern. @ascarpino, do you remember what this class was made
for and whether it is obsolete now?
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/30941#discussion_r3430793498
