On Tue, 11 Jun 2019, Jan Hubicka wrote:
> > So the important thing is that during matching the paths
> > aptr->a and *bptr we return false for
> > same_type_for_tbaa (int *, struct a *), correct? But if
> > we can do that then the alias sets should not conflict in
> > the first place and we shouldn't need any path-based disambiguation
> > here.
> >
> > So to me this is the wrong place to fix.
>
> The alias sets of int * conflict with alias set of struct a *
> since that one is same as void * and we make void * to conflict
> with all pointers.
>
> However we also do not want to return -1 for things like
> same_type_for_tbaa (int *, struct a)
> which we do currently, since int * is TYPE_STRUCTURAL_EQUALITY
> and struct a is not.
Yes, but that basically boils down to handling !AGGREGATE_TYPE_P
vs AGGREGATE_TYPE_P in a better way, not looking into pointed-to
types.
> Here you may declare struct a as
> struct a {int *a;};
> and alias sets will be in conflict even w/o void * globing.
>
> Honza
>
--
Richard Biener <[email protected]>
SUSE Linux GmbH, Maxfeldstrasse 5, 90409 Nuernberg, Germany;
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