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Subject: [Bug bootstrap/55388] [4.8 regression] ICE in int_mode_for_mode at stor-layout.c:423 breaks sparc64-linux bootstrap
Date: Thu, 22 Nov 2012 17:48:00 -0000
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55388

Eric Botcazou <ebotcazou at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
         AssignedTo|unassigned at gcc dot       |ebotcazou at gcc dot
                   |gnu.org                     |gnu.org
   Target Milestone|---                         |4.8.0

--- Comment #10 from Eric Botcazou <ebotcazou at gcc dot gnu.org> 2012-11-22 17:47:38 UTC ---
> It's caused by r193599:
> http://gcc.gnu.org/ml/gcc-cvs/2012-11/msg00546.html

Yep, the problem is that alias.c:nonoverlapping_component_refs_p considers that
accesses to bitfields never overlap with accesses to other components...

I also think that the size handling in set_mem_attributes_minus_bitpos might
need to be further refined, now that bitfields are handled:

       /* Respect mode size.  */
      attrs.size_known_p = defattrs->size_known_p;
      attrs.size = defattrs->size;
      /* ??? Is this really necessary?  We probably should always get
     the size from the type below.  */

I don't see how the final size can be smaller than the mode size.