https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92131
--- Comment #10 from Eric Botcazou <ebotcazou at gcc dot gnu.org> ---
> IIRC compare_values doesn't look at symbolic SSA names value-range but it
> should do the same as fold would do for -7 < e.7_8 + (+INF - 1) which
> IIRC doesn't fold this because combining the two constants results in an
> overflow. So that's likely a bug in compare_values to say -1 here:
>
> /* Compute the difference between the constants. If it overflows or
> underflows, this means that we can trivially compare the NAME with
> it and, consequently, the two values with each other. */
> wide_int diff = wi::to_wide (cst) - wi::to_wide (inv);
> if (wi::cmp (0, wi::to_wide (inv), sgn)
> != wi::cmp (diff, wi::to_wide (cst), sgn))
> {
> const int res = wi::cmp (wi::to_wide (cst), wi::to_wide (inv),
> sgn);
> return cst1 ? res : -res;
> }
IIRC this was directly copied from fold_comparison.
