https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84648
--- Comment #3 from bin cheng <amker at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #2)
> So we run into
>
> /* Ignore loops of while (i-- < 10) type. */
> if (code != NE_EXPR)
> {
> if (iv0->step && tree_int_cst_sign_bit (iv0->step))
> return false;
>
> if (!integer_zerop (iv1->step) && !tree_int_cst_sign_bit (iv1->step))
> return false;
> }
>
> where code == LE_EXPR from 0 <= iv1 with iv1 being {0, +, 1}.
>
> This specifically singles out loop-until-wrap. We'd need to teach niter
> analysis this kind of loop.
Thanks, I will have a look how niter analysis should be improved for this.
