[PATCH 4/4] openacc: Allow strided arrays in update directives

[Tobias Burnus]

LGTM.

However, I'd feel better if there were a testcase, which actually
checks that it works correctly. (I think that means a
libgomp/testsuite/ run test.)

Tobias

On 02.02.21 14:28, Julian Brown wrote:
> OpenACC 3.0 ("2.14.4. Update Directive") states:
>
>    Noncontiguous subarrays may appear. It is implementation-specific
>    whether noncontiguous regions are updated by using one transfer for
>    each contiguous subregion, or whether the non-contiguous data is
>    packed, transferred once, and unpacked, or whether one or more larger
>    subarrays (no larger than the smallest contiguous region that contains
>    the specified subarray) are updated.
>
> This patch relaxes some conditions in the Fortran front-end so that
> strided accesses are permitted for update directives.
>
> Tested with offloading to AMD GCN. OK for mainline?
>
> Thanks,
>
> Julian
>
> 2020-02-02  Julian Brown  <julian@codesourcery.com>
>
> gcc/fortran/
>       * openmp.c (resolve_omp_clauses): Omit OpenACC update in
>       contiguity check and stride-specified error.
>
> gcc/testsuite/
>       * gfortran.dg/goacc/array-with-dt-2.f90: New test.
> ---
>   gcc/fortran/openmp.c                                |  5 +++--
>   gcc/testsuite/gfortran.dg/goacc/array-with-dt-2.f90 | 10 ++++++++++
>   2 files changed, 13 insertions(+), 2 deletions(-)
>   create mode 100644 gcc/testsuite/gfortran.dg/goacc/array-with-dt-2.f90
>
> diff --git a/gcc/fortran/openmp.c b/gcc/fortran/openmp.c
> index 9a3a8f63b5e..1c8c5315329 100644
> --- a/gcc/fortran/openmp.c
> +++ b/gcc/fortran/openmp.c
> @@ -5192,7 +5192,8 @@ resolve_omp_clauses (gfc_code *code, gfc_omp_clauses *omp_clauses,
>                          array isn't contiguous.  An expression such as
>                          arr(-n:n,-n:n) could be contiguous even if it looks
>                          like it may not be.  */
> -                     if (list != OMP_LIST_CACHE
> +                     if (code->op != EXEC_OACC_UPDATE
> +                         && list != OMP_LIST_CACHE
>                           && list != OMP_LIST_DEPEND
>                           && !gfc_is_simply_contiguous (n->expr, false, true)
>                           && gfc_is_not_contiguous (n->expr))
> @@ -5224,7 +5225,7 @@ resolve_omp_clauses (gfc_code *code, gfc_omp_clauses *omp_clauses,
>                       int i;
>                       gfc_array_ref *ar = &array_ref->u.ar;
>                       for (i = 0; i < ar->dimen; i++)
> -                       if (ar->stride[i])
> +                       if (ar->stride[i] && code->op != EXEC_OACC_UPDATE)
>                           {
>                             gfc_error ("Stride should not be specified for "
>                                        "array section in %s clause at %L",
> diff --git a/gcc/testsuite/gfortran.dg/goacc/array-with-dt-2.f90 b/gcc/testsuite/gfortran.dg/goacc/array-with-dt-2.f90
> new file mode 100644
> index 00000000000..807580d75a9
> --- /dev/null
> +++ b/gcc/testsuite/gfortran.dg/goacc/array-with-dt-2.f90
> @@ -0,0 +1,10 @@
> +type t
> +   integer, allocatable :: A(:,:)
> +end type t
> +
> +type(t), allocatable :: b(:)
> +
> +!$acc update host(b(::2))
> +!$acc update host(b(1)%A(::3,::4))
> +end
> +
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