[Bug tree-optimization/77550] [6/7 Regression] std::deque with -O3 has infinite std::distance

["pinskia at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77550

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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                 CC|                            |rguenth at gcc dot gnu.org

--- Comment #10 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Bernd Edlinger from comment #9)
> I'm unable to reduce the test case...
> 
> 
> The deque_iterator has these members:
> 
>       _Elt_pointer _M_cur;
>       _Elt_pointer _M_first;
>       _Elt_pointer _M_last;
>       _Map_pointer _M_node;
> 
> the first 3 elements have alias set 12
> while _M_node has alias set 13.
> 
> when all 4 elements are assigned that becomes
> 2 vector statements, but all use alias set 12.

The vector stores should have become the aliasing set of the struct instead as
suggested on the store widening patch.