[Patch]GCC11 - Fortran: combined directives - order(concurrent) not on distribute (was: Re: [Patch] Fortran/OpenMP: unconstrained/reproducible ordered modifier)

[Tobias Burnus <tobias@codesourcery.com>]

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On 20.09.21 11:55, Jakub Jelinek via Fortran wrote:
> So the FE was splitting the order clause to distribute already before,
> perhaps we should undo that for gcc 11 which doesn't claim any OpenMP 5.1
> support.
> The difference is e.g. the distribute parallel do order(concurrent) copyin(thr)
> case which used to be ok in 5.0 and is not in 5.1.

Well, if I try with GCC 11:

void f(int *a)
{
int  i;
static int thr;
#pragma omp threadprivate (thr)
#pragma omp distribute parallel for order(concurrent) copyin(thr)
   for (i = 0; i < 10; ++i)
    {
     thr = 5;
     a[i] = thr;
    }
}

I get with gcc (+ gfortran):
   error: threadprivate variable ‘thr’ used in a region with ‘order(concurrent)’ clause
I might have misunderstood the example.

  * * *

In any case, for GCC 11, I have now fixed the splitting and added a testcase which
relies on -fdump-tree-original scanning and does not use threadprivate.

OK for GCC 11, only?

Tobias

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GCC11 - Fortran: combined directives - order(concurrent) not on distribute

While OpenMP 5.1 and GCC 12 permits 'order(concurrent)' on distribute,
OpenMP 5.0 and GCC 11 don't. This patch for GCC 11 ensures the clause also
does not end up on 'distribute' when splitting combined directives.

gcc/fortran/ChangeLog:

	* trans-openmp.c (gfc_split_omp_clauses): Don't put 'order(concurrent)'
	on 'distribute' for combined directives, matching OpenMP 5.0

gcc/testsuite/ChangeLog:

	* gfortran.dg/gomp/distribute-order-concurrent.f90: New test.

 gcc/fortran/trans-openmp.c                         |  2 --
 .../gomp/distribute-order-concurrent.f90           | 25 ++++++++++++++++++++++
 2 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/gcc/fortran/trans-openmp.c b/gcc/fortran/trans-openmp.c
index 7e931bf4bc7..973d916b4a2 100644
--- a/gcc/fortran/trans-openmp.c
+++ b/gcc/fortran/trans-openmp.c
@@ -5176,8 +5176,6 @@ gfc_split_omp_clauses (gfc_code *code,
 	  /* Duplicate collapse.  */
 	  clausesa[GFC_OMP_SPLIT_DISTRIBUTE].collapse
 	    = code->ext.omp_clauses->collapse;
-	  clausesa[GFC_OMP_SPLIT_DISTRIBUTE].order_concurrent
-	    = code->ext.omp_clauses->order_concurrent;
 	}
       if (mask & GFC_OMP_MASK_PARALLEL)
 	{
diff --git a/gcc/testsuite/gfortran.dg/gomp/distribute-order-concurrent.f90 b/gcc/testsuite/gfortran.dg/gomp/distribute-order-concurrent.f90
new file mode 100644
index 00000000000..9597d913684
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/gomp/distribute-order-concurrent.f90
@@ -0,0 +1,25 @@
+! { dg-additional-options "-fdump-tree-original" }
+!
+! In OpenMP 5.0, 'order(concurrent)' does not apply to distribute
+! Ensure that it is rejected in GCC 11.
+! 
+! Note: OpenMP 5.1 allows it; the GCC 12 testcase for it is gfortran.dg/gomp/order-5.f90
+
+subroutine f(a)
+implicit none
+integer :: i, thr
+!save :: thr
+integer :: a(:)
+
+!$omp distribute parallel do order(concurrent) private(thr)
+  do i = 1, 10
+    thr = 5
+    a(i) = thr
+  end do
+!$omp end distribute parallel do
+end
+
+! { dg-final { scan-tree-dump-not "omp distribute\[^\n\r]*order" "original" } }
+! { dg-final { scan-tree-dump "#pragma omp distribute\[\n\r\]" "original" } }
+! { dg-final { scan-tree-dump "#pragma omp parallel private\\(thr\\)" "original" } }
+! { dg-final { scan-tree-dump "#pragma omp for nowait order\\(concurrent\\)" "original" } }