https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97721
--- Comment #8 from Aldy Hernandez <aldyh at gcc dot gnu.org> ---
(In reply to Jakub Jelinek from comment #7)
> But TREE_OVERFLOW is meaningful during evaluation, e.g. inside of VRP or
> when folding some expression. It just doesn't belong into the GIMPLE IL.
> So I'd say it would be better for ranger when it sees TREE_OVERFLOW constant
> somewhere in the IL not to set the range to that constant, but to
> drop_tree_overflow of it.
That's certainly the easiest path for us. We could drop_overflow in
get_tree_range while creating said ranges, and then no other changes to the
ranger are needed.
However, I wonder if compare_values_warnv is being unnecessarily restrictive.
For example, here, we bail on overflow, even though tree_int_cst_compare,
through its use of wi::cmps, is perfectly capable of comparing these integers:
if (!POINTER_TYPE_P (TREE_TYPE (val1)))
{
/* We cannot compare overflowed values. */
if (TREE_OVERFLOW (val1) || TREE_OVERFLOW (val2))
return -2;
if (TREE_CODE (val1) == INTEGER_CST
&& TREE_CODE (val2) == INTEGER_CST)
return tree_int_cst_compare (val1, val2);
as well as here:
if (TREE_CODE (val1) == INTEGER_CST && TREE_CODE (val2) == INTEGER_CST)
{
/* We cannot compare overflowed values. */
if (TREE_OVERFLOW (val1) || TREE_OVERFLOW (val2))
return -2;
return tree_int_cst_compare (val1, val2);
}
