[Bug bootstrap/53681] s390 bootstrap failure since 187965

[rguenther at suse dot de]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53681

--- Comment #6 from rguenther at suse dot de <rguenther at suse dot de> 2012-06-18 08:24:51 UTC ---
On Mon, 18 Jun 2012, krebbel at gcc dot gnu.org wrote:

> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53681
> 
> --- Comment #5 from Andreas Krebbel <krebbel at gcc dot gnu.org> 2012-06-18 07:09:04 UTC ---
> (In reply to comment #4)
> > I don't see how r187965 could cause this, but I do see the problem.
> > mark_sym_for_renaming (called via the s390 va_arg_expr expander) is called
> > during, well, gimplification from GENERIC.  At that point SSA isn't
> > initialized yet, so cfun->gimple_df is still NULL, and so SYMS_TO_RENAME
> > gives a segfault.
> > 
> > You either have to guard the call to mark_sym_for_renaming with
> > gimple_in_ssa_p(), or get rid of the call alltogether.  I don't see how
> > new va_arg expressions would be generated during SSA optimizers, so the latter
> > solution would be safe.  No other backend calls mark_sym_for_renaming either,
> > so just remove it.
> 
> ?! You appear to have added the call to mark_sym_for_renaming with your patch.
> Since it isn't mentioned in the changelog perhaps it is a leftover from
> something else in your tree? So the solution is to revert that change?
> 
> svn diff -r 187964:187965 gcc/config/s390/s390.c
> Index: gcc/config/s390/s390.c
> ===================================================================
> --- gcc/config/s390/s390.c      (revision 187964)
> +++ gcc/config/s390/s390.c      (revision 187965)
> @@ -9044,6 +9044,7 @@
>    lab_false = create_artificial_label (UNKNOWN_LOCATION);
>    lab_over = create_artificial_label (UNKNOWN_LOCATION);
>    addr = create_tmp_var (ptr_type_node, "addr");
> +  mark_sym_for_renaming (addr);

I think that change is indeed bogus as-is, if you ever call this
when we are in SSA form you'd need that call, but you need to guard
it with if (gimple_in_ssa_p (cfun)).

But I'm sure we never gimplify va-arg stuff when in SSA form.

Richard.