[Bug tree-optimization/58570] [4.9 Regression] wrong code for bitfields at -O2 and above

[ebotcazou at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58570

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|bernd.edlinger at hotmail dot de   |
           Assignee|unassigned at gcc dot gnu.org      |ebotcazou at gcc dot 
gnu.org
            Summary|[4.9 Regression] wrong code |[4.9 Regression] wrong code
                   |at -Os and above on         |for bitfields at -O2 and
                   |x86_64-linux-gnu (both      |above
                   |32-bit and 64-bit modes)    |

--- Comment #5 from Eric Botcazou <ebotcazou at gcc dot gnu.org> ---
I think we just want to copy the following from
nonoverlapping_component_refs_p:

      /* If we're left with accessing different fields of a structure, then no
     possible overlap, unless they are both bitfields.  */
      if (TREE_CODE (typex) == RECORD_TYPE && fieldx != fieldy)
    return !(DECL_BIT_FIELD (fieldx) && DECL_BIT_FIELD (fieldy));

over to nonoverlapping_component_refs_of_decl_p.