[Bug middle-end/64491] [5 Regression] incorrect warning: loop exit may only be reached after undefined behavior

["joona.kiiski at gmail dot com" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64491

--- Comment #5 from joona.kiiski at gmail dot com ---
Thanks for confirming the problem, Joost!

* The original reporter stated that also 4.9 branch is affected, but I
haven't tested this myself. No idea about 4.8 branch.

* Latest gcc stable releases (4.7.4, 4.8.4, 4.9.2) compile Stockfish
without this warning, so I assume that they are not affected.

* For Stockfish, the generated code is correct (despite the wrong analysis
by GCC). However I'm aware that GCC can do some aggressive optimizations in
this area, so in other cases, who knows...


On Sat, Jan 10, 2015 at 4:49 PM, Joost.VandeVondele at mat dot ethz.ch <
gcc-bugzilla@gcc.gnu.org> wrote:

> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64491
>
> Joost VandeVondele <Joost.VandeVondele at mat dot ethz.ch> changed:
>
>            What    |Removed                     |Added
>
> ----------------------------------------------------------------------------
>              Status|WAITING                     |NEW
>    Last reconfirmed|2015-01-04 00:00:00         |2015-1-10
>                  CC|                            |Joost.VandeVondele at mat
> dot ethz
>                    |                            |.ch
>             Summary|warning: loop exit may only |[5 Regression] incorrect
>                    |be reached after undefined  |warning: loop exit may
> only
>                    |behavior                    |be reached after undefined
>                    |                            |behavior
>       Known to fail|                            |5.0
>
> --- Comment #4 from Joost VandeVondele <Joost.VandeVondele at mat dot
> ethz.ch> ---
> The incorrect warning is confirmed.
>
> I wonder if this incorrect analysis could lead to wrong code generation.
>
> --
> You are receiving this mail because:
> You are on the CC list for the bug.
>