On Mon, 21 Sep 2020, Jan Hubicka wrote:
> > On Sun, 20 Sep 2020, Jan Hubicka wrote:
> >
> > > Hi,
> > > this is patch I am using to fix the assumed_alias_type.f90 failure by
> > > simply arranging alias set 0 for the problematic array descriptor.
> >
> > There's no such named testcase on trunk. Can you be more specific
> > as to the problem at hand? It looks like gfortran.dg/assumed_type_9.f90
> > execute FAILs at the moment.
> >
> > In particular how's this not an issue w/o IPA modref?
>
> >
> > For TYPE(*) I think the object itself cannot be accessed but for
> > arrays the meta-info in the array descriptor can. Now my question
> > would be why the Fortran FE at the call site does not build an
> > appropriately typed array descriptor?
> >
> > CCing the fortran list.
>
> The problem is:
>
> alsize (struct array15_unknown & restrict a)
> {
> ...
> _2 = *a_13(D).dtype.rank;
> _3 = (integer(kind=8)) _2;
> ...
> }
> }
> and in main:
>
> struct array02_integer(kind=4) am;
> <bb 6> :
> MEM <c_char[8]> [(struct dtype_type *)&am + 24B] = {};
> am.dtype.elem_len = 4;
> am.dtype.rank = 2;
> am.dtype.type = 1;
> ...
> _52 = alsize (&am);
>
> Here array15_unknown and array02_integer are different structures with
> different canonical types and thus we end up disambiguating the accesses
> via base alias sets.
>
> My understanding is that this _unknown array descriptor is supposed to
> be universal and work with all kinds of arrays.
But the FE builds a new descriptor for each individual call and thus
should build a universal descriptor for a call to an universal
descriptor argument.
Richard.
> Wihtout modref this works because alsize is not inlined (we think code
> size would grow). Forcing inliner to inline stil leads to working code
> because we first constant propagate the pointer and then we see accesses
> from same base DECL thus bypass the TBAA checks. Disabling the
> constant propagation leads to wrong code as wel.
>
> Honza
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
Germany; GF: Felix Imend
