[PATCH] Fix PR79278, amend ADJUST_FIELD_ALIGN interface

[Jakub Jelinek]

On Wed, Feb 01, 2017 at 10:27:27AM -0500, Trevor Saunders wrote:
> Yeah, different targets deal with this mess in different ways, looks
> like frv uses a different macro and ppc redefines macros as needed
> rs6000_special_adjust_field_align_p is also defined in ppc headers.
> 
> > 
> > /* @@@ A hack, needed because libobjc wants to use ADJUST_FIELD_ALIGN for
> >    some reason.  */
> > #ifdef IN_TARGET_LIBS
> > #define BIGGEST_FIELD_ALIGNMENT 64
> > #else
> > /* An expression for the alignment of a structure field FIELD if the
> >    alignment computed in the usual way is COMPUTED.  GCC uses this
> >    value instead of the value in `BIGGEST_ALIGNMENT' or
> >    `BIGGEST_FIELD_ALIGNMENT', if defined, for structure fields only.  */
> > #define ADJUST_FIELD_ALIGN(FIELD, COMPUTED)                             \
> >   frv_adjust_field_align (FIELD, COMPUTED)
> > #endif
> > 
> > Similar x86_64.
> > 
> > So it seems on power this might be an issue and thus I'd need to
> > adjust the macro use - but not sure what to pass as "type" here...
> 
> Sorry but I seem to have successfully purged my brain of the details on
> how this works.

IMNSHO what libobjc should have used is just some new builtin that would
allow it to query such information from the compiler.

	Jakub