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Re: Does vectorizer support extension?
On Tue, Apr 24, 2007 at 08:55:24PM +0300, Dorit Nuzman wrote:
> "H. J. Lu" <hjl@lucon.org> wrote on 24/04/2007 01:03:25:
> ...
> >
> > There are
> >
> > [hjl@gnu-2 vect]$ cat pmovzxbw.c
> > typedef unsigned char vec_t;
> > typedef unsigned short vecx_t;
> >
> > in
> >
> > http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31667
> >
>
> By the way, this PR says "Integer externsions aren't vectorized" - but I
> think the testcase you are referring to does get vectorized, only not as
> efficiently as you would want it to (right?).
I was referring to extensions including things like V2QI -> V2DI.
> It
> > isn't easy to move N/2 high elemenets to N/2 low elemenets.
>
> just curious - why is it difficult? (couldn't you use a psrldq? is it too
> expensive?)
It needs more instructions.
H.J.