On Tue, 3 May 2011, Michael Matz wrote:
> Hi,
>
> On Tue, 3 May 2011, Richard Guenther wrote:
>
> > --- 5858,5890 ----
> >
> > /* If these are the same operation types, we can associate them
> > assuming no overflow. */
> > ! if (tcode == code)
> > ! {
> > ! double_int mul;
> > ! int overflow_p;
> > ! mul = double_int_mul_with_sign
> > ! (double_int_ext
> > ! (tree_to_double_int (op1),
> > ! TYPE_PRECISION (ctype), TYPE_UNSIGNED (ctype)),
> > ! double_int_ext
> > ! (tree_to_double_int (c),
> > ! TYPE_PRECISION (ctype), TYPE_UNSIGNED (ctype)),
> > ! false, &overflow_p);
> > ! overflow_p = (((!TYPE_UNSIGNED (ctype)
> > ! || (TREE_CODE (ctype) == INTEGER_TYPE
> > ! && TYPE_IS_SIZETYPE (ctype))) && overflow_p)
> > ! | TREE_OVERFLOW (c) | TREE_OVERFLOW (op1));
> > ! if (!double_int_fits_to_tree_p (ctype, mul)
> > ! && ((TYPE_UNSIGNED (ctype) && tcode != MULT_EXPR)
> > ! || (!(TYPE_UNSIGNED (ctype) && tcode != MULT_EXPR)
> > ! && (!TYPE_UNSIGNED (ctype)
> > ! || (TREE_CODE (ctype) == INTEGER_TYPE
> > ! && TYPE_IS_SIZETYPE (ctype))))))
>
> Doubled "(TYPE_UNSIGNED (ctype) && tcode != MULT_EXPR)". Clearer is:
>
> if (!double_int_fits_to_tree_p (ctype, mul)
> && ((TYPE_UNSIGNED (ctype) && tcode != MULT_EXPR)
> || !TYPE_UNSIGNED (ctype)
> || (TREE_CODE (ctype) == INTEGER_TYPE
> && TYPE_IS_SIZETYPE (ctype))))
Indeed, fixed.
> I've tried to determine if it's otherwise an equivalent transformation but
> became confused with your intermediate updating of the overflow_p flag.
> The new code sort of makes sense but I can't say if it's exactly what the
> old code did :)
:) Another question is why exactly the old code did what it did.
Richard.
