[Bug fortran/46271] New: OpenMP default(none) and procedure pointers

[Bug fortran/46271] New: OpenMP default(none) and procedure pointers

[mrestelli at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46271

           Summary: OpenMP default(none) and procedure pointers
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: mrestelli@gmail.com


gfortran rejects the attached code both in version A and B. A similar
problem is discussed in

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44036

but, to my understanding, this only covers the case of a procedure
pointer associated with a function, not the subroutine case.


gfortran --version
GNU Fortran (GCC) 4.6.0 20101019 (experimental)


With version A:
gfortran -fopenmp omp_test.f90 -o omp_test
omp_test.f90:22.59:

  !$omp   private(i) shared(s,pf) default(none) ! version A
                                                           1
Error: Object 'pf' is not a variable at (1)

With version B:
gfortran -fopenmp omp_test.f90 -o omp_test
omp_test.f90: In function ‘test’:
omp_test.f90:25:0: error: ‘pf’ not specified in enclosing parallel
omp_test.f90:23:0: error: enclosing parallel



module ma
 implicit none
contains
 pure subroutine f(x,y)
  real, intent(in) :: x
  real, intent(out) :: y
   y = sin(x)*cos(x)
 end subroutine f
end module ma

program test
 use ma, only: f
 implicit none
 integer :: i
 real :: s(1000)
 procedure(f), pointer :: pf

  pf => f

  !$omp parallel do schedule(static) &
  ! !$omp   private(i) shared(s,pf) default(none) ! version A
  !$omp   private(i) shared(s) default(none) ! version B
  do i=1,1000
    call pf(real(i),s(i))
  enddo
  !$omp end parallel do

  write(*,*) 'Sum ',sum(s)
end program test

[Bug fortran/46271] OpenMP default(none) and procedure pointers

[dominiq at lps dot ens.fr]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46271

Dominique d'Humieres <dominiq at lps dot ens.fr> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2013-06-23
     Ever confirmed|0                           |1

--- Comment #1 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
Still present at revision 200321.

[Bug fortran/46271] [F03] OpenMP default(none) and procedure pointers

[janus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46271

janus at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
                 CC|                            |janus at gcc dot gnu.org
           Assignee|unassigned at gcc dot gnu.org      |janus at gcc dot gnu.org
            Summary|OpenMP default(none) and    |[F03] OpenMP default(none)
                   |procedure pointers          |and procedure pointers

--- Comment #2 from janus at gcc dot gnu.org ---
Here is a simple patch to accept version A:


Index: gcc/fortran/openmp.c
===================================================================
--- gcc/fortran/openmp.c    (revision 201653)
+++ gcc/fortran/openmp.c    (working copy)
@@ -847,7 +847,7 @@ resolve_omp_clauses (gfc_code *code)
     for (n = omp_clauses->lists[list]; n; n = n->next)
       {
     n->sym->mark = 0;
-    if (n->sym->attr.flavor == FL_VARIABLE)
+    if (n->sym->attr.flavor == FL_VARIABLE || n->sym->attr.proc_pointer)
       continue;
     if (n->sym->attr.flavor == FL_PROCEDURE
         && n->sym->result == n->sym
@@ -876,8 +876,6 @@ resolve_omp_clauses (gfc_code *code)
         if (el)
           continue;
           }
-        if (n->sym->attr.proc_pointer)
-          continue;
       }
     gfc_error ("Object '%s' is not a variable at %L", n->sym->name,
            &code->loc);

[Bug fortran/46271] [F03] OpenMP default(none) and procedure pointers

[janus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46271

--- Comment #3 from janus at gcc dot gnu.org ---
(In reply to mrestelli from comment #0)
> With version B:
> gfortran -fopenmp omp_test.f90 -o omp_test
> omp_test.f90: In function ‘test’:
> omp_test.f90:25:0: error: ‘pf’ not specified in enclosing parallel
> omp_test.f90:23:0: error: enclosing parallel

What is actually the problem here? That error message looks correct to me,
doesn't it?
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http://gcc.gnu.org/bugzilla/show_bug.cgi?idW717

jules at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jules at gcc dot gnu.org

--- Comment #7 from jules at gcc dot gnu.org ---
Here's another candidate patch:

http://gcc.gnu.org/ml/gcc-patches/2013-08/msg00668.html

[Bug fortran/46271] [F03] OpenMP default(none) and procedure pointers

[janus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46271

--- Comment #4 from janus at gcc dot gnu.org ---
(In reply to janus from comment #2)
> Here is a simple patch to accept version A:

... which regtests cleanly!

[Bug fortran/46271] [F03] OpenMP default(none) and procedure pointers

[mrestelli at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46271

--- Comment #5 from mrestelli <mrestelli at gmail dot com> ---
(In reply to janus from comment #3)
> (In reply to mrestelli from comment #0)
> > With version B:
> > gfortran -fopenmp omp_test.f90 -o omp_test
> > omp_test.f90: In function ‘test’:
> > omp_test.f90:25:0: error: ‘pf’ not specified in enclosing parallel
> > omp_test.f90:23:0: error: enclosing parallel
> 
> What is actually the problem here? That error message looks correct to me,
> doesn't it?

Janus, you are probably right that version B should not compile. I
guess when I posted the bug report I was not sure which was the
correct version according to the OpenMP specifications, since fp is a
variable (requiring an OpenMP attribute), but it behaves like a
subroutine (so, no OpenMP attribute). Clearly however at least one of
the two versions should work, hence my pointing out that both
alternatives do not work. Well, at least this is my recollection,
since it was quite a while ago.

As a note, I mention that ifort (version 13.1) accepts both versions,
but maybe this is an issue with ifort itself.

Regards,
   Marco Restelli
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Subject: [Bug fortran/46271] [F03] OpenMP default(none) and procedure pointers
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http://gcc.gnu.org/bugzilla/show_bug.cgi?idF271

--- Comment #6 from janus at gcc dot gnu.org ---
Hi Marco,

> Janus, you are probably right that version B should not compile. I
> guess when I posted the bug report I was not sure which was the
> correct version according to the OpenMP specifications, since fp is a
> variable (requiring an OpenMP attribute), but it behaves like a
> subroutine (so, no OpenMP attribute).

well, since a procedure pointer can be assigned and change its value, I would
say it counts as a variable and one should make up one's mind whether it is
supposed to be shared or private in an OpenMP loop (as for any other variable,
this can clearly make a difference). Hence my interpretation that the error
message is correct.

However, I should note that I'm not much of an OpenMP expert and haven't
checked whether the OpenMP specifications makes any definitive statement about
this. It's merely my 'gut feeling'.


> As a note, I mention that ifort (version 13.1) accepts both versions,
> but maybe this is an issue with ifort itself.

ifort is not exactly known for it's strictness on invalid programs, and of
course it may have bugs. I don't know if this is allowed on purpose or if the
missing error is an oversight.

If ifort accepts the program, it would be interesting whether it treats the
procptr as private or shared with default(none), and whether this behavior is
documented somewhere (either in the OpenMP spec or the ifort docs).

Some people claim that documentation is the only thing that distinguishes a
feature from a bug ;)

Cheers,
Janus

[Bug fortran/46271] [F03] OpenMP default(none) and procedure pointers

[janus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46271

janus at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |FIXED

--- Comment #7 from janus at gcc dot gnu.org ---
(In reply to janus from comment #2)
> Here is a simple patch to accept version A:

... which has been committed to 4.9 trunk:


Author: janus
Date: Mon Aug 19 09:03:20 2013
New Revision: 201835

URL: http://gcc.gnu.org/viewcvs?rev=201835&root=gcc&view=rev
Log:
2013-08-19  Janus Weil  <janus@gcc.gnu.org>

    PR fortran/46271
    * openmp.c (resolve_omp_clauses): Bugfix for procedure pointers.


2013-08-19  Janus Weil  <janus@gcc.gnu.org>

    PR fortran/46271
    * gfortran.dg/gomp/proc_ptr_1.f90: New.

Added:
    trunk/gcc/testsuite/gfortran.dg/gomp/proc_ptr_1.f90
Modified:
    trunk/gcc/fortran/ChangeLog
    trunk/gcc/fortran/openmp.c
    trunk/gcc/testsuite/ChangeLog



I think the rejection of version B is ok (see above discussion), therefore I'm
closing this PR. Thanks for the report!