Re: [PATCH] Fix PRs 52080, 52097 and 48124, rewrite bitfield expansion, enable the C++ memory model wrt bitfields everywhere

[Richard Guenther <rguenther at suse dot de>]

On Thu, 15 Mar 2012, Eric Botcazou wrote:

> > Ok, I applied a fix for PR52134 and am preparing a fix for PR52578.
> > It seems we might not be able to rely on
> >
> >       tree maxsize = size_diffop (TYPE_SIZE_UNIT (DECL_CONTEXT (field)),
> >                                   DECL_FIELD_OFFSET (repr));
> >       gcc_assert (host_integerp (maxsize, 1));
> >
> > but at least until we get a testcase that shows so I won't add
> > (unexercised) code that handles it.  Eventually we'd need to treat
> > tail-padding specially for some languages anyway, via a new langhook.
> 
> This caused 3 classes of problems in Ada:
> 
>   1. failure of the above assertion (pack7.ads)
>   2. ICE in tree_low_cst (pack16.adb, pack16_pkg.ads)
>   3. miscompilation (to be dealt with later).
> 
> 1. and 2. appear to come from variable-sized fields (and 3. from record types 
> with variant part).  Testcases attached, they can be installed as:
> 
>   gnat.dg/pack16.adb
>   gnat.dg/pack16_pkg.ads
>   gnat.dg/specs/pack7.ads
> 
> in the testsuite.

I'll address these and add the testcases.

Thanks,
Richard.