Re: overflow check in extract_range_from_binary_1 useless?

[Richard Biener <richard.guenther@gmail.com>]

On Fri, Jun 8, 2018 at 11:42 AM Aldy Hernandez <aldyh@redhat.com> wrote:
>
> Howdy.
>
> Am I missing something or are these two sets identical?
>
> >         /* Get the lower and upper bounds of the type.  */
> >         if (TYPE_OVERFLOW_WRAPS (expr_type))
> >           {
> >             type_min = wi::min_value (prec, sgn);
> >             type_max = wi::max_value (prec, sgn);
> >           }
> >         else
> >           {
> >             type_min = wi::to_wide (vrp_val_min (expr_type));
> >             type_max = wi::to_wide (vrp_val_max (expr_type));
> >           }
>
> Isn't wi::to_wide(TYPE_MIN/MAX_VALUE) the same as wi::min/max_value, or
> is there some weird language (*cough ada*) subtlety I'm missing?

It might have subtle differences for -fstrict-enums or other language specific
types where the legal value-range doesn't cover all of the types precision.

I think you can safely use the wi::max/min_value variant and IMHO
vrp_val_min/max should use wi::min/max_value as well (well, it returns
a tree so better not re-create that all the time).

Richard.

> Confused.
> Aldy