https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98758
--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to David Binderman from comment #5)
> Minor quibble over the patch. I notice that integer division by abs_b occurs.
>
> Belt and braces, but is zero a legal value for abs_b ?
>
> If so, it might be worth putting in some code to avoid divide by zero.
>
> If not, it might be worth putting in some code to show the future
> readers of the code that integer division by zero doesn't happen.
The code is (more fully quoted)
while (S[i][j] != 0)
{
lambda_int sigma, factor, a, b;
a = S[i-1][j];
b = S[i][j];
sigma = ((a < 0) ^ (b < 0)) ? -1: 1;
unsigned HOST_WIDE_INT abs_a = absu_hwi (a);
unsigned HOST_WIDE_INT abs_b = absu_hwi (b);
factor = sigma * (lambda_int)(abs_a / abs_b);
lambda_matrix_row_add (S, n, i, i-1, -factor);
std::swap (S[i], S[i-1]);
lambda_matrix_row_add (U, m, i, i-1, -factor);
std::swap (U[i], U[i-1]);
}
so b is not zero. I'm investigating how to handle possible overflow
in lambda_matrix_row_add still.
