On Fri, 2005-04-08 at 18:58 +0200, Jakub Jelinek wrote:
> On Fri, Apr 08, 2005 at 10:52:02AM -0600, Jeffrey A Law wrote:
> > There's a rather annoying bug in the vectorizer which can cause us to
> > have SSA_NAMEs which are used, but never defined.
> >
> > Consider this testcase compiled with -msse2 -ftree-vectorize:
> >
> > typedef char achar __attribute__ ((__aligned__(16)));
> > int main1 ()
> > {
> > struct {
> > achar *p;
> > achar *q;
> > } s;
> > int i;
> > achar x[16];
> > achar cb[16];
> > s.p = x;
> > i = 0;
> > do
> > {
> > s.p[i] = cb[i];
> > i++;
> > } while (i < 16);
> >
> > if (s.p[0])
> > abort ();
> > }
>
> See middle-end/20794, there is discussion about declaring this
> invalid. When a type with size that is not an integral multiple
> of alignment (e.g. smaller size than alignment) is used in an
> array, we have the choice either to violate the alignment
> request for second and some subsequent array elements,
> or make the elements bigger, but then pointer arithmetics
> won't work very well.
But is that likely the cause for getting a different set of virtual
operands for the scalar and vector versions of the store? That's
the real problem here.
jeff
