Fix bootstrap issue with gcc 4.1

[Jan Hubicka]

> On Thu, May 4, 2017 at 11:04 AM, Jan Hubicka <hubicka@ucw.cz> wrote:
> >> >
> >> >Sure, I'm not questioning the patch, just wondering if we shouldn't
> >> >improve
> >> >store-merging further (we want to do it anyway for e.g. bitop adjacent
> >> >operations etc.).
> >>
> >> We definitely want to do that.  It should also 'nicely' merge with bswap for gathering the load side of a piecewise memory to memory copy.
> >
> > The code we produce now in .optimized is:
> >   <bb 8> [15.35%]:
> >   # DEBUG this => _42
> >   MEM[(struct inline_summary *)_42].estimated_self_stack_size = 0;
> >   MEM[(struct inline_summary *)_42].self_size = 0;
> >   _44 = &MEM[(struct inline_summary *)_42].self_time;
> >   # DEBUG this => _44
> >   # DEBUG sig => 0
> >   # DEBUG exp => 0
> >   MEM[(struct sreal *)_42 + 16B].m_sig = 0;
> >   MEM[(struct sreal *)_42 + 16B].m_exp = 0;
> >   sreal::normalize (_44);
> >   # DEBUG this => NULL
> >   # DEBUG sig => NULL
> >   # DEBUG exp => NULL
> >   MEM[(struct inline_summary *)_42].min_size = 0;
> >   MEM[(struct inline_summary *)_42].inlinable = 0;
> >   MEM[(struct inline_summary *)_42].contains_cilk_spawn = 0;
> >   MEM[(struct inline_summary *)_42].single_caller = 0;
> >   MEM[(struct inline_summary *)_42].fp_expressions = 0;
> >   MEM[(struct inline_summary *)_42].estimated_stack_size = 0;
> >   MEM[(struct inline_summary *)_42].stack_frame_offset = 0;
> 
> It should handle at least the bitfields here (inlinable, contains_cilk_spawn,
> single_caller and fp_expression).  Ah, I guess it doesn't because the
> padding isn't initialized and it doesn't want to touch it.  Well, just a guess.
> 
> inline_summary is also very badly laid out now with lots of padding.

Yep, I am aware it does not make sense now after reorganization.  I plan to break it
into inliner independent part and inliner hints and then I will fix layout ;)

Honza
> 
> >   _45 = &MEM[(struct inline_summary *)_42].time;
> >   # DEBUG this => _45
> >   # DEBUG sig => 0
> >   # DEBUG exp => 0
> >   MEM[(struct sreal *)_42 + 56B].m_sig = 0;
> >   MEM[(struct sreal *)_42 + 56B].m_exp = 0;
> >   sreal::normalize (_45);
> >   # DEBUG this => NULL
> >   # DEBUG sig => NULL
> >   # DEBUG exp => NULL
> >   MEM[(struct inline_summary *)_42].size = 0;
> >   MEM[(void *)_42 + 80B] = 0;
> >   MEM[(void *)_42 + 88B] = 0;
> >   MEM[(void *)_42 + 96B] = 0;
> >   MEM[(struct predicate * *)_42 + 104B] = 0;
> >   MEM[(void *)_42 + 112B] = 0;
> >   MEM[(void *)_42 + 120B] = 0;
> >   goto <bb 10>; [100.00%]
> >
> > so indeed it is not quite pretty at all. Even the bitfields are split
> > and there is offlined call to normlize zero in sreal.
> > I wonder why inliner does not see htis as obviously good inlining oppurtunity.
> > I will look into that problem. For store merging it would indeed be
> > very nice to improve this as well.
> >
> > Honza
> >>
> >> Richard.
> >>
> >> >
> >> >     Jakub