On Mon, Jun 18, 2012 at 04:44:21PM -0700, Richard Henderson wrote:
> On 2012-06-14 13:58, Jakub Jelinek wrote:
> > + if (!supportable_widening_operation (WIDEN_MULT_EXPR, last_stmt,
> > + vecwtype, vectype,
> > + &dummy, &dummy, &dummy_code,
> > + &dummy_code, &dummy_int, &dummy_vec))
> > + return NULL;
>
>
> It would be nice to be able to handle high-part multiplies as well, e.g.
> VEC_WIDEN_MULT_HI_EXPR. Which is what Altivec provides, and not
> VEC_WIDEN_MULT.
Sure, but we don't have a tree code for that right now, do we?
VEC_WIDEN_MULT_HI_EXPR is just one half of the widened multiply results,
not all the high halves of the widened multiply.
For 16-bit multiplication we could also use {,V}PMULH{,U}W
(for 32-bit multiplication we use two {,V}PMUL{,U}DQ plus shifts afterwards).
Jakub
