On Tue, Nov 19, 2024 at 10:06 AM Richard Biener
<richard.guent...@gmail.com> wrote:
>
> On Sun, Nov 17, 2024 at 4:30 AM Lewis Hyatt <lhy...@gmail.com> wrote:
> >
> > The size of struct gimple increases by 8 bytes with the change in size of
> > location_t from 32- to 64-bit; adjust the WORD markings in the comments
> > accordingly. It seems that most of the WORD markings were off by one
> > already,
> > probably not having been updated after a previous reduction in the size of a
> > gimple, so they have become retroactively correct again, and only a couple
> > needed adjustment actually.
> >
> > Also move the 32-bit num_ops member of struct gimple to the end; since there
> > is now 4 bytes of padding after it, this may enable reuse of the tail
> > padding for some derived structures.
> >
> > gcc/ChangeLog:
> >
> > * gimple.h (struct gimple): Update word marking comments to reflect
> > the new size of location_t. Move the 32-bit int field to the end.
> > (struct gphi): Likewise.
> > ---
> > gcc/gimple.h | 11 ++++++-----
> > 1 file changed, 6 insertions(+), 5 deletions(-)
> >
> > diff --git a/gcc/gimple.h b/gcc/gimple.h
> > index 4a6e0e97d1e..6929c792dc5 100644
> > --- a/gcc/gimple.h
> > +++ b/gcc/gimple.h
> > @@ -268,9 +268,6 @@ struct GTY((desc ("gimple_statement_structure (&%h)"),
> > tag ("GSS_BASE"),
> > Locus information for debug info. */
> > location_t location;
> >
> > - /* Number of operands in this tuple. */
> > - unsigned num_ops;
> > -
>
> Can you instead swap location and num_ops and insert
>
> unsigned int pad : 32;
>
> after the bits section? Or is the intent to allow the tail padding to
> be re-used? I guess
> all the [ WORD 1-n] : base class comments need adjustment? Since
> 'gimple' looks POD
> to me, is tail padding even re-used?
>
> Thanks,
> Richard.
So I was thinking that the tail padding could be reused, but you are
right, it won't be here since this is the base class. All the classes
that inherit from gimple are non-POD because they use inheritance, but
gimple itself is POD. I'll change it how you suggest.
