Re: [patch] Fortran fix for PR70289

[Jakub Jelinek <jakub at redhat dot com>]

On Fri, Apr 01, 2016 at 08:07:24AM -0700, Cesar Philippidis wrote:
> On 04/01/2016 07:56 AM, Jakub Jelinek wrote:
> > On Fri, Apr 01, 2016 at 07:49:16AM -0700, Cesar Philippidis wrote:
> >> The bug in PR70289 is an assertion failure triggered by a static
> >> variable used inside an offloaded acc region which doesn't have a data
> >> clause associated with it. Basically, that static variable ends up in a
> >> different lto partition, which was not streamed to the offloaded
> >> compiler. I'm not sure if we should try to replicate the static storage
> >> in the offloaded regions, but it probably doesn't make sense in a
> >> parallel environment anyway.
> > 
> > Is this really Fortran specific?  I'd expect the diagnostics to be in
> > gimplify.c and handle it for all 3 FEs...
> 
> By the time the variable reaches the gimplifier, the reduction variable
> may no longer match the ones inside the data clause. E.g. consider this
> directive inside a fortran subroutine:
> 
>   !$acc parallel copyout(temp) reduction(+:temp)
> 
> The gimplifier would see something like:
> 
>   map(force_from:*temp.2 [len: 4]) map(alloc:temp [pointer assign, bias:
> 0]) reduction(+:temp)
> 
> At this point, unless I'm mistaken, it would be difficult to tell if
> temp.2 is a pointer to the same temp in the reduction. Maybe I'm missing
> something?

All the info is still there, and this wouldn't be the only case where
we rely on exact clause ordering.  I think that is still much better than
doing it in all the FEs.

	Jakub