Re: [patch, fortran] Remove parallell annotation from DO CONCURRENT

[Richard Biener <richard.guenther@gmail.com>]

On Mon, Apr 9, 2018 at 10:58 PM, Thomas Koenig <tkoenig@netcologne.de> wrote:
> Hi Steve,
>
>> On Mon, Apr 09, 2018 at 10:10:13PM +0200, Thomas Koenig wrote:
>>>
>>>
>>> the attached patch removes the parallel annotation from DO CONCURRENT.
>>> As discussed in the PR, the autoparallellizer currently generates
>>> wrong code. The only feasible way is to disable the annotation for
>>> gcc-8 and work on the wrong-code issues for gcc-9. This is an 8
>>> regression.
>>>
>>> Regression-tested. OK for trunk?
>>>
>>
>> Yes.
>
>
> Thanks for the review!
>
> However, just as I was about to commit, I thought of something else
> and, hopefully, better.
>
> The underlying problem is that the annotation does not go together
> with -ftree-parallelize-loops - so let's simply not set it if that
> flag is set.
>
> This way, we can avoid speed regressions for people who do not use
> -ftree-parallelize-loops, and it will be possible to downgrade the
> PR to a missed-optimization bug; it is also not necessary to xfail
> vect-do-concurrent-1.f90
>
> Regression-tested. OK for trunk, for this version?

flag_tree_parallelize_loops is 1 by default (and doesn't parallelize then,
the flag specifies the number of threads).  The pass is also run if
flag_openacc.

Note that setting the attribute is only ever useful for autopar, nothing
else looks at it.  I think before I made the change there was the
ivdep flag set which should be still valid (in fact lowering of parallel_kind
sets both can_be_parallel and safelen).

So I suggest to instead unconditonally replace parallel_kind with
ivdep_kind.

Richard.

>
> 2018-04-09  Thomas Koenig  <tkoenig@gcc.gnu.org>
>
>         PR fortran/83064
>         * trans-stmt.c (gfc_trans_forall_loop): Remove annotation for
>         parallell processing of DO CONCURRENT -ftree-parallelize-loops
>         is set.
>
> 2018-04-09  Thomas Koenig  <tkoenig@gcc.gnu.org>
>
>         PR fortran/83064
>         * gfortran.dg/do_concurrent_5.f90: New test.
>         * gfortran.dg/vect/vect-do-concurrent-1.f90: Adjust dg-bogus
>         message.