Hi!
On Wed, 4 Nov 2015 18:21:36 +0100, Jakub Jelinek <ja...@redhat.com> wrote:
> On Wed, Nov 04, 2015 at 06:15:14PM +0100, Thomas Schwinge wrote:
> > > --- a/gcc/fortran/openmp.c
> > > +++ b/gcc/fortran/openmp.c
> >
> > > @@ -3028,6 +3015,22 @@ resolve_omp_clauses (gfc_code *code,
> > > gfc_omp_clauses *omp_clauses,
> > > n->sym->mark = 1;
> > > }
> > >
> > > + /* OpenACC reductions. */
> > > + if (openacc)
> > > + {
> > > + for (n = omp_clauses->lists[OMP_LIST_REDUCTION]; n; n = n->next)
> > > + n->sym->mark = 0;
> >
> > Maybe I'm just confugsed, but if setting all these to zero here...
> >
> > > +
> > > + for (n = omp_clauses->lists[OMP_LIST_REDUCTION]; n; n = n->next)
> > > + {
> > > + if (n->sym->mark)
> > > + gfc_error ("Symbol %qs present on multiple clauses at %L",
> > > + n->sym->name, &n->where);
> > > + else
> > > + n->sym->mark = 1;
> >
> > ... won't this just always run into the "else" branch?
>
> The point is to check if some symbol isn't present multiple times in
> reduction clause(s). So the first loop clears the flag as it could have
> arbitrary values, and the second loop will diagnose an error if n->sym
> is present multiple times in the list. reduction(+: a, b, a) and the like.
> In C/C++ FE we use bitmaps for this, in Fortran FE we have mark
> field for those purposes.Thanks for the explanation -- I'd missed the fact that several "n" might refer to the same "sym"... ;-) Grüße Thomas
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