Re: Suggestion for a moratorium on short-circuit IF

[Janus Weil <janus at gcc dot gnu dot org>]

Hi Thomas,

sorry, but I don't really understand why you're making such a fuzz
about this issue.

Sure, the discussion of the whole topic has been a bit lengthy and
quite controversial (and part of the blame certainly goes to the
Fortran standard for not being more stringent in this area). But in
the end I would say that the process was quite useful. It has helped
to illuminate the issue from all angles and brought up all relevant
boundary conditions.

>From my point of view the debate has crystallized into a very clear
end result: Short-circuiting is not mandatory in Fortran, but it is a
useful and important optimization. My proposal (and in fact two other
people have proposed this before me) was to treat it like every other
optimization and enable it with -O flags (providing the best possible
performance), but disable it with -O0 (in order to allow for debugging
and error diagnostics).

It seems that for some reason you have a diffuse aversion to this
approach, but you haven't really explained why.

I would strongly prefer to have a factual debate, instead of somebody
killing off the topic as non-debatable. Please explain what the
problem is. I think I'm a reasonable person and open to objective
arguments. However, I don't understand at all why this topic is such a
holy cow and afflicted with so much dogma.

So, a simple question to you personally: Why, in your opinion, is it
so utterly important to do short-circuiting at -O0? I really see no
good reason why we should.

Cheers,
Janus

PS: Regarding the beers-at-the-cauldron thing ... that really is an
excellent idea and I was actually trying to make it happen, but
unfortunately there are severe personal-life constraints that make it
hard if not impossible for me to come to Manchester in September
(which is not quite around the corner from where I live).



2018-07-25 23:23 GMT+02:00 Thomas Koenig <tkoenig@netcologne.de>:
> Hi,
>
> after some thoughts and off-line discussion with another contributor,
> I would like to propose a moratorium on this topic.
>
> It seems that we are unable to agree to a course of action, or even
> the direction that the course should take us.  Also, I think that
> a continuing disagreement could do more harm to gfortran development
> than this topic actually merits.
>
> So, my proposal would be to freeze the current status, which is better
> than gcc 8 because we have added a warning that was not there before,
> and because we now have the documentation that users can turn to.
>
> I would also like to thank Janus for the work he has put into this,
> and the other participants of the discussion.
>
> Maybe we can discuss this over a beer at the GNU cauldron (hint, hint).
> I'll buy a round.
>
> Regards
>
>         Thomas