Hi,
On Wed, 20 Apr 2011, Richard Guenther wrote:
> > I had occasion to try this today; this inheritance structure doesn't
> > work. The truncated inheritance tree looks like:
> >
> > * decl_common
> > * field_decl
> > * const_decl
> > * decl_with_rtl
> > * label_decl
> > * result_decl
> > * parm_decl
> > * decl_with_vis...
> >
> > In particular, FIELD_DECLs have a size, but they have no RTL associated
> > with them. And LABEL_DECLs have RTL, but no size.
Blaeh. So far about nice clean ideas :) One hacky idea: change my
proposal to this:
decl_common {} # no size, no rtl, no align, no pt_uid
decl_with_rtl_or_size : decl_common {
# add align, pt_uid
union {
rtx rtl;
tree size;
} u;
}
decl_with_size : decl_with_rtl_or_size {
# add size, size_unit
}
Use the rtl_or_size struct primarily for the current _with_rtl things that
don't naturally have a size, but use it also for FIELD_DECLs via the
union.
Alternatively I could also envision making a new tree_ struct for just
field_decls, that would contain the size and other fields that currently
are in decl_common just for fields (in particular the off_align) member.
The various accessors like DECL_SIZE would then need to dispatch based on
tree code.
Also doesn't sound terribly sexy.
FWIW I'm usually against on the side mappings A->B if most As will most of
the time be associated with a B. A size _is_ associated with the entity
always (for entities where it makes sense to talk about sizes), so that's
exactly where I would find on the side tables strange. For DECL_RTL it's
less clear.
Ciao,
Michael.
