PR85463 '[nvptx] "exit" in offloaded region doesn't terminate process' (was: [patch, libfortran, committed] Implement stop_numeric for minimal targets)

[Thomas Schwinge]

Hi!

On Thu, 19 Apr 2018 11:25:30 +0200, Jakub Jelinek <jakub@redhat.com> wrote:
> On Thu, Apr 19, 2018 at 11:19:31AM +0200, Thomas Schwinge wrote:
> > On Thu, 19 Apr 2018 11:14:38 +0200, Jakub Jelinek <jakub@redhat.com> wrote:
> > > On Thu, Apr 19, 2018 at 11:06:18AM +0200, Thomas Schwinge wrote:
> > > > On Wed, 4 Apr 2018 11:30:34 +0200, Thomas König <tk@tkoenig.net> wrote:
> > > > > the recent patch to make the gfortran and libgomp testsuites more
> > > > > standard conforming, by replacing CALL ABORT() with STOP N, led
> > > > > to numerous testsuite failures on nvptx because stop_numeric
> > > > > was not implemented in minimal.c.
> > > > > 
> > > > > I have committed the patch below in r259072 as obvious after Tom
> > > > > de Vries had confirmed that it solves the problem.
> > > > 
> > > > ... for some meaning of "solves the problem"; see below.  ;-) Which you
> > > > couldn't know, of course.  (So, definitely thanks anyway, for promptly
> > > > addressing the issue raised!)
> > > 
> > > My preference would be just to revert the call abort to stop n changes
> > > in target regions.
> > 
> > That seems backwards to me -- having "exit" (as well as Fortran language
> > "stop" and "error stop") inside offloaded regions do the right thing is
> > something we wanted to do anyway, eventually.
> 
> I'm looking for a GCC8 fix, and for that it seems like the simplest
> and safest solution.

As far as I know, the "call abort to stop n" changes regressed nvptx
targets only, and that's now fixed (and improved to handle more Fortran
language "stop" and "error stop" variants), so I don't see a reason to
iterate once again?  (Or, why didn't you then already dispute Thomas
König's nvptx/libgfortran minimal.c patch adding stop_numeric?)


> > > Mapping exit to abort is weird
> > 
> > Sure, that's why PR85463 is still open, and has some (initial)
> > comments/ideas regarding that.
> > 
> > > and making exit terminate whole process even
> > > when called from offloaded regions might be too expensive.
> > 
> > In what way "too expensive"?
> 
> If you need to add code to handle that case to every target region entry
> just in case something does stop, the slow down might be too high and
> unacceptable.  Depends on how it is implemented.

Right, but that's again "why PR85463 is still open, and has some
(initial) comments/ideas regarding that", and no overhead has so far been
introduced.


Grüße
 Thomas