On Thu, 30 Jun 2011, Sebastian Pop wrote:
> On Thu, Jun 30, 2011 at 05:19, Richard Guenther <rguent...@suse.de> wrote:
> > That looks odd. So you given -1U as input you sign-extend that to -1
>
> correct
>
> > and then set the mpz to -1ULLL.
>
> and then it sets the mpz to signed -1, given that I'm passing false to UNS:
>
> /* Sets RESULT to VAL, taken unsigned if UNS is true and as signed
> otherwise. */
>
> void
> mpz_set_double_int (mpz_t result, double_int val, bool uns)
>
> > In fact it looks like you either
> > have non-canoncial INTEGER_CSTs from the start or the type of the
> > integer constants is wrong.
>
> I don't know what a canonical INTEGER_CST is.
Canonically extended according to TYPE_UNSIGNED I mean. So what you
do is always create signed mpzs - that should simply work without
doing anything to the double-int. Thus, why not do
static inline void
tree_int_to_gmp (tree t, mpz_t res)
{
double_int di = tree_to_double_int (t);
mpz_set_double_int (res, di, false);
}
? I don't see why you'd want to sign-extend unsigned values
(for example an unsigned char 255 would get sign-extended to -1).
As double_ints are always correctly extended according to the
sign of the INTEGER_CST they come from (iff they are properly
canonical) you can embed all INTEGER_CSTs with precision of max.
HOST_BITS_PER_WISE_INT * 2 into a signed mpz with precision
HOST_BITS_PER_WISE_INT * 2 + 1.
> Here are the cases that can occur:
> - translating to mpz a -1U as the upper bound of an unsigned type,
> in which case I do not want it to be sign extended,
> - translating to mpz a -1U constant in an unsigned expression "x + -1U"
> in which I do want it to be sign extended.
I don't think you want the 2nd. I think you want to preserve the
value.
Richard.
