Re: [committed] - Re: [patch] OpenMP/Fortran: Non-rectangular loops with constant steps other than 1 or -1 [PR107424]

[Thomas Schwinge <thomas@codesourcery.com>]

Hi Tobias!

On 2023-07-19T10:26:12+0200, Tobias Burnus <tobias@codesourcery.com> wrote:
> Now committed as Rev. r14-2634-g85da0b40538fb0

On devel/omp/gcc-13 branch, the corresponding
commit b003e6511754dce475f7f5b0c5cd887a177e41b3
"OpenMP/Fortran: Non-rectangular loops with constant steps other than 1 or -1 [PR107424]"
introduces a regression:

    PASS: libgomp.fortran/loop-transforms/unroll-2.f90   -O0  (test for excess errors)
    [-PASS:-]{+FAIL:+} libgomp.fortran/loop-transforms/unroll-2.f90   -O0  execution test

Etc.

    spawn [open ...]
               4
               8
              10
              11

    Program aborted. Backtrace:
    #0  0x400f9c in test
            at [...]/libgomp.fortran/loop-transforms/unroll-2.f90:85
    #1  0x400fd3 in main
            at [...]/libgomp.fortran/loop-transforms/unroll-2.f90:59


Grüße
 Thomas


> Changes:
>
> * I missed to updated another 'sorry' (msg wording change) - now fixed;
> I also added it to the sorry-testcase file non-rectangular-loop-5.f90.
>
> * I decided to retire the PR as several issues have been fixed and the
> original title did not fit any more. The remaining issue is now tracked
> in PR110735 (i.e. handling step != const, both the generic and possibly
> a simpler special case).
>
> * I added a link to the PR to libgomp.texi such that one can find out
> what is only partially supported for Fortran.
>
> Thanks,
>
> Tobias
>
> PS: Otherwise, the following still applies:
>
> On 18.07.23 14:11, Tobias Burnus wrote:
>> Comments regarding the validity of the Fortran assumptions are welcome!
>>
>> This patch now uses a 'simple' loop for OpenMP loops with
>> a constant loop-step size. Before, it only did so for step = ±1.
>> (Otherwise, a count variable is used from which the original
>> loop index variable is calculated from.)
>>
>> For details, see the attached patch or
>> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107424#c12
>> (comment 12 + 14 plus the email linked in comment 12).
>>
>> Comments? Remarks? If there are none, I will relatively soonish
>> commit the attached patch to mainline, only.

> commit 85da0b40538fb0d17d89de1e7905984668e3dfef
> Author: Tobias Burnus <tobias@codesourcery.com>
> Date:   Wed Jul 19 10:18:49 2023 +0200
>
>     OpenMP/Fortran: Non-rectangular loops with constant steps other than 1 or -1 [PR107424]
>
>     Before this commit, gfortran produced with OpenMP for 'do i = 1,10,2'
>     the code
>       for (count.0 = 0; count.0 < 5; count.0 = count.0 + 1)
>         i = count.0 * 2 + 1;
>
>     While such an inner loop can be collapsed, a non-rectangular could not.
>     With this commit and for all constant loop steps, a simple loop such
>     as 'for (i = 1; i <= 10; i = i + 2)' is created. (Before only for the
>     constant steps of 1 and -1.)
>
>     The constant step permits to know the direction (increasing/decreasing)
>     that is required for the loop condition.
>
>     The new code is only valid if one assumes no overflow of the loop variable.
>     However, the Fortran standard can be read that this must be ensured by
>     the user. Namely, the Fortran standard requires (F2023, 10.1.5.2.4):
>     "The execution of any numeric operation whose result is not defined by
>     the arithmetic used by the processor is prohibited."
>
>     And, for DO loops, F2023's "11.1.7.4.3 The execution cycle" has the
>     following: The number of loop iterations handled by an iteration count,
>     which would permit code like 'do i = huge(i)-5, huge(i),4'. However,
>     in step (3), this count is not only decremented by one but also:
>       "... The DO variable, if any, is incremented by the value of the
>       incrementation parameter m3."
>     And for the example above, 'i' would be 'huge(i)+3' in the last
>     execution cycle, which exceeds the largest model number and should
>     render the example as invalid.
>
>             PR fortran/107424
>
>     gcc/fortran/ChangeLog:
>
>             * trans-openmp.cc (gfc_nonrect_loop_expr): Accept all
>             constant loop steps.
>             (gfc_trans_omp_do): Likewise; use sign to determine
>             loop direction.
>
>     libgomp/ChangeLog:
>
>             * libgomp.texi (Impl. Status 5.0): Add link to new PR110735.
>             * testsuite/libgomp.fortran/non-rectangular-loop-1.f90: Enable
>             commented tests.
>             * testsuite/libgomp.fortran/non-rectangular-loop-1a.f90: Remove
>             test file; tests are in non-rectangular-loop-1.f90.
>             * testsuite/libgomp.fortran/non-rectangular-loop-5.f90: Change
>             testcase to use a non-constant step to retain the 'sorry' test.
>             * testsuite/libgomp.fortran/non-rectangular-loop-6.f90: New test.
>
>     gcc/testsuite/ChangeLog:
>
>             * gfortran.dg/gomp/linear-2.f90: Update dump to remove
>             the additional count variable.
> ---
>  gcc/fortran/trans-openmp.cc                        |  18 +-
>  gcc/testsuite/gfortran.dg/gomp/linear-2.f90        |   4 +-
>  libgomp/libgomp.texi                               |   4 +-
>  .../libgomp.fortran/non-rectangular-loop-1.f90     | 537 ++++++++++-----------
>  .../libgomp.fortran/non-rectangular-loop-1a.f90    | 374 --------------
>  .../libgomp.fortran/non-rectangular-loop-5.f90     |  22 +-
>  .../libgomp.fortran/non-rectangular-loop-6.f90     | 196 ++++++++
>  7 files changed, 494 insertions(+), 661 deletions(-)
>
> diff --git a/gcc/fortran/trans-openmp.cc b/gcc/fortran/trans-openmp.cc
> index c88ee3c7656..cf741cebf91 100644
> --- a/gcc/fortran/trans-openmp.cc
> +++ b/gcc/fortran/trans-openmp.cc
> @@ -5374,10 +5374,10 @@ gfc_nonrect_loop_expr (stmtblock_t *pblock, gfc_se *sep, int loop_n,
>
>    if (!simple)
>      {
> -      /* FIXME: Handle non-unit iter steps, cf. PR fortran/107424.  */
> +      /* FIXME: Handle non-const iter steps, cf. PR fortran/110735.  */
>        sorry_at (gfc_get_location (&curr_loop_var->where),
> -             "non-rectangular loop nest with step other than constant 1 "
> -             "or -1 for %qs", curr_loop_var->symtree->n.sym->name);
> +             "non-rectangular loop nest with non-constant step for %qs",
> +             curr_loop_var->symtree->n.sym->name);
>        return false;
>      }
>
> @@ -5394,10 +5394,10 @@ gfc_nonrect_loop_expr (stmtblock_t *pblock, gfc_se *sep, int loop_n,
>         }
>       else
>         {
> -         /* FIXME: Handle non-unit iter steps, cf. PR fortran/107424.  */
> +         /* FIXME: Handle non-const iter steps, cf. PR fortran/110735.  */
>           sorry_at (gfc_get_location (&code->loc),
> -                   "non-rectangular loop nest with step other than constant "
> -                   "1 or -1 for %qs", var->name);
> +                   "non-rectangular loop nest with non-constant step "
> +                   "for %qs", var->name);
>           inform (gfc_get_location (&expr->where), "Used here");
>           return false;
>         }
> @@ -5578,10 +5578,8 @@ gfc_trans_omp_do (gfc_code *code, gfc_exec_op op, stmtblock_t *pblock,
>        gfc_add_block_to_block (pblock, &se.pre);
>        step = gfc_evaluate_now (se.expr, pblock);
>
> -      if (integer_onep (step))
> -     simple = 1;
> -      else if (tree_int_cst_equal (step, integer_minus_one_node))
> -     simple = -1;
> +      if (TREE_CODE (step) == INTEGER_CST)
> +     simple = tree_int_cst_sgn (step);
>
>        gfc_init_se (&se, NULL);
>        if (!clauses->non_rectangular
> diff --git a/gcc/testsuite/gfortran.dg/gomp/linear-2.f90 b/gcc/testsuite/gfortran.dg/gomp/linear-2.f90
> index 05f007fd5c2..88df96e9b8f 100644
> --- a/gcc/testsuite/gfortran.dg/gomp/linear-2.f90
> +++ b/gcc/testsuite/gfortran.dg/gomp/linear-2.f90
> @@ -105,8 +105,8 @@ end module
>  ! { dg-final { scan-tree-dump-times "#pragma omp for nowait" 6 "original" } }
>  ! { dg-final { scan-tree-dump-times "#pragma omp for linear\\(x:D\\.\[0-9\]+\\) nowait" 1 "original" } }
>  ! { dg-final { scan-tree-dump-times "#pragma omp for linear\\(x:val,step\\(D\\.\[0-9\]+\\)\\) nowait" 1 "original" } }
> -! { dg-final { scan-tree-dump-times "#pragma omp simd linear\\(count\\.\[0-9\]:1\\) linear\\(i:3\\)" 2 "original" } }
> -! { dg-final { scan-tree-dump-times "#pragma omp simd linear\\(count\\.\[0-9\]:1\\) linear\\(i:val,step\\(3\\)\\)" 2 "original" } }
> +! { dg-final { scan-tree-dump-times "#pragma omp simd linear\\(i:3\\)" 2 "original" } }
> +! { dg-final { scan-tree-dump-times "#pragma omp simd linear\\(i:val,step\\(3\\)\\)" 2 "original" } }
>  ! { dg-final { scan-tree-dump-times "#pragma omp simd linear\\(i:1\\) linear\\(x:D\\.\[0-9\]+\\)" 2 "original" } }
>  ! { dg-final { scan-tree-dump-times "#pragma omp simd linear\\(i:1\\) linear\\(x:val,step\\(D\\.\[0-9\]+\\)\\)" 2 "original" } }
>  ! { dg-final { scan-tree-dump-times "#pragma omp simd linear\\(i:D\\.\[0-9\]+\\)" 2 "original" } }
> diff --git a/libgomp/libgomp.texi b/libgomp/libgomp.texi
> index 639dd05eb7b..a8582b50177 100644
> --- a/libgomp/libgomp.texi
> +++ b/libgomp/libgomp.texi
> @@ -194,7 +194,9 @@ The OpenMP 4.5 specification is fully supported.
>  @item @code{requires} directive @tab P
>        @tab complete but no non-host device provides @code{unified_shared_memory}
>  @item @code{teams} construct outside an enclosing target region @tab Y @tab
> -@item Non-rectangular loop nests @tab P @tab Full support for C/C++, partial for Fortran
> +@item Non-rectangular loop nests @tab P
> +      @tab Full support for C/C++, partial for Fortran
> +           (@uref{https://gcc.gnu.org/PR110735,PR110735})
>  @item @code{!=} as relational-op in canonical loop form for C/C++ @tab Y @tab
>  @item @code{nonmonotonic} as default loop schedule modifier for worksharing-loop
>        constructs @tab Y @tab
> diff --git a/libgomp/testsuite/libgomp.fortran/non-rectangular-loop-1.f90 b/libgomp/testsuite/libgomp.fortran/non-rectangular-loop-1.f90
> index dbbd18a1444..d074d4de5a0 100644
> --- a/libgomp/testsuite/libgomp.fortran/non-rectangular-loop-1.f90
> +++ b/libgomp/testsuite/libgomp.fortran/non-rectangular-loop-1.f90
> @@ -6,9 +6,6 @@
>
>  ! Nonrectangular loop nests checks
>
> -! See PR or non-rectangular-loop-1a.f90 for the commented tests
> -! Hint: Those use step for loop vars part of nonrectangular loop nests
> -
>  module m
>    implicit none (type, external)
>  contains
> @@ -26,32 +23,32 @@ subroutine lastprivate_check_simd_1
>    ! Use 'i' or 'j', unit step on 'i' or on 'j' -> 4 loops
>    ! Then same, except use non-unit step for 'k'
>
> -!  !$omp simd collapse(3) lastprivate(k)
> -!  do i = 1, n
> -!    do j = 1, m, 2
> -!      do k = j - 41, p
> -!        if (k < 1 - 41 .or. k > p) error stop
> -!      end do
> -!    end do
> -!  end do
> -!  if (k /= p + 1) error stop
> -
> -!  !$omp simd collapse(3) lastprivate(k)
> -!  do i = 1, n, 2
> -!    do j = 1, m
> -!      do k = i - 41, p
> -!        if (k < 1 - 41 .or. k > p) error stop
> -!      end do
> -!    end do
> -!  end do
> -!  if (k /= p + 1) error stop
> +  !$omp simd collapse(3) lastprivate(k)
> +  do i = 1, n
> +    do j = 1, m, 2
> +      do k = j - 41, p
> +        if (k < 1 - 41 .or. k > p) error stop
> +      end do
> +    end do
> +  end do
> +  if (k /= p + 1) error stop
> +
> +  !$omp simd collapse(3) lastprivate(k)
> +  do i = 1, n, 2
> +    do j = 1, m
> +      do k = i - 41, p
> +        if (k < 1 - 41 .or. k > p) error stop
> +      end do
> +    end do
> +  end do
> +  if (k /= p + 1) error stop
>
>    !$omp simd collapse(3) lastprivate(k)
>    do i = 1, n, 2
>      do j = 1, m
>        do k = j - 41, p
>          if (k < 1 - 41 .or. k > p) then
> -          print *, i, j, k,p, " -> i, j, k, p   (k < 1 - 41 .or. k > p)"
> +          ! print *, i, j, k,p, " -> i, j, k, p   (k < 1 - 41 .or. k > p)"
>            error stop
>          end if
>        end do
> @@ -66,7 +63,7 @@ subroutine lastprivate_check_simd_1
>      do j = 1, m
>        do k = j - 41, p
>          if (k < 1 - 41 .or. k > p) then
> -          print *, i, j, k,p, " -> i, j, k, p   (k < 1 - 41 .or. k > p)"
> +          ! print *, i, j, k,p, " -> i, j, k, p   (k < 1 - 41 .or. k > p)"
>            error stop
>          end if
>        end do
> @@ -102,25 +99,25 @@ subroutine lastprivate_check_simd_1
>
>    ! Same but 'private' for all (i,j) vars
>
> -!  !$omp simd collapse(3) lastprivate(k) private(i,j)
> -!  do i = 1, n
> -!    do j = 1, m, 2
> -!      do k = j - 41, p
> -!        if (k < 1 - 41 .or. k > p) error stop
> -!      end do
> -!    end do
> -!  end do
> -!  if (k /= p + 1) error stop
> -!
> -!  !$omp simd collapse(3) lastprivate(k) private(i,j)
> -!  do i = 1, n, 2
> -!    do j = 1, m
> -!      do k = i - 41, p
> -!        if (k < 1 - 41 .or. k > p) error stop
> -!      end do
> -!    end do
> -!  end do
> -!  if (k /= p + 1) error stop
> +  !$omp simd collapse(3) lastprivate(k) private(i,j)
> +  do i = 1, n
> +    do j = 1, m, 2
> +      do k = j - 41, p
> +        if (k < 1 - 41 .or. k > p) error stop
> +      end do
> +    end do
> +  end do
> +  if (k /= p + 1) error stop
> +
> +  !$omp simd collapse(3) lastprivate(k) private(i,j)
> +  do i = 1, n, 2
> +    do j = 1, m
> +      do k = i - 41, p
> +        if (k < 1 - 41 .or. k > p) error stop
> +      end do
> +    end do
> +  end do
> +  if (k /= p + 1) error stop
>
>    !$omp simd collapse(3) lastprivate(k) private(i,j)
>    do i = 1, n, 2
> @@ -144,27 +141,27 @@ subroutine lastprivate_check_simd_1
>
>    ! Same - but with lastprivate(i,j)
>
> -!  !$omp simd collapse(3) lastprivate(k) lastprivate(i,j)
> -!  do i = 1, n
> -!    do j = 1, m, 2
> -!      do k = j - 41, p
> -!        if (k < 1 - 41 .or. k > p) error stop
> -!      end do
> -!    end do
> -!  end do
> -!  if (k /= p + 1) error stop
> -!  if (i /= n + 1 .or. j /= m + 2) error stop
> -
> -!  !$omp simd collapse(3) lastprivate(k) lastprivate(i,j)
> -!  do i = 1, n, 2
> -!    do j = 1, m
> -!      do k = i - 41, p
> -!        if (k < 1 - 41 .or. k > p) error stop
> -!      end do
> -!    end do
> -!  end do
> -!  if (k /= p + 1) error stop
> -!  if (i /= n + 2 .or. j /= m + 1) error stop
> +  !$omp simd collapse(3) lastprivate(k) lastprivate(i,j)
> +  do i = 1, n
> +    do j = 1, m, 2
> +      do k = j - 41, p
> +        if (k < 1 - 41 .or. k > p) error stop
> +      end do
> +    end do
> +  end do
> +  if (k /= p + 1) error stop
> +  if (i /= n + 1 .or. j /= m + 2) error stop
> +
> +  !$omp simd collapse(3) lastprivate(k) lastprivate(i,j)
> +  do i = 1, n, 2
> +    do j = 1, m
> +      do k = i - 41, p
> +        if (k < 1 - 41 .or. k > p) error stop
> +      end do
> +    end do
> +  end do
> +  if (k /= p + 1) error stop
> +  if (i /= n + 2 .or. j /= m + 1) error stop
>
>    !$omp simd collapse(3) lastprivate(k) lastprivate(i,j)
>    do i = 1, n, 2
> @@ -201,25 +198,25 @@ subroutine lastprivate_check_do_simd_1
>    ! Use 'i' or 'j', unit step on 'i' or on 'j' -> 4 loops
>    ! Then same, except use non-unit step for 'k'
>
> -!  !$omp parallel do simd collapse(3) lastprivate(k)
> -!  do i = 1, n
> -!    do j = 1, m, 2
> -!      do k = j - 41, p
> -!        if (k < 1 - 41 .or. k > p) error stop
> -!      end do
> -!    end do
> -!  end do
> -!  if (k /= p + 1) error stop
> -
> -!  !$omp parallel do simd collapse(3) lastprivate(k)
> -!  do i = 1, n, 2
> -!    do j = 1, m
> -!      do k = i - 41, p
> -!        if (k < 1 - 41 .or. k > p) error stop
> -!      end do
> -!    end do
> -!  end do
> -!  if (k /= p + 1) error stop
> +  !$omp parallel do simd collapse(3) lastprivate(k)
> +  do i = 1, n
> +    do j = 1, m, 2
> +      do k = j - 41, p
> +        if (k < 1 - 41 .or. k > p) error stop
> +      end do
> +    end do
> +  end do
> +  if (k /= p + 1) error stop
> +
> +  !$omp parallel do simd collapse(3) lastprivate(k)
> +  do i = 1, n, 2
> +    do j = 1, m
> +      do k = i - 41, p
> +        if (k < 1 - 41 .or. k > p) error stop
> +      end do
> +    end do
> +  end do
> +  if (k /= p + 1) error stop
>
>    !$omp parallel do simd collapse(3) lastprivate(k)
>    do i = 1, n, 2
> @@ -243,25 +240,25 @@ subroutine lastprivate_check_do_simd_1
>
>    ! Same but 'private' for all (i,j) vars
>
> -!  !$omp parallel do simd collapse(3) lastprivate(k) private(i,j)
> -!  do i = 1, n
> -!    do j = 1, m, 2
> -!      do k = j - 41, p
> -!        if (k < 1 - 41 .or. k > p) error stop
> -!      end do
> -!    end do
> -!  end do
> -!  if (k /= p + 1) error stop
> -
> -!  !$omp parallel do simd collapse(3) lastprivate(k) private(i,j)
> -!  do i = 1, n, 2
> -!    do j = 1, m
> -!      do k = i - 41, p
> -!        if (k < 1 - 41 .or. k > p) error stop
> -!      end do
> -!    end do
> -!  end do
> -!  if (k /= p + 1) error stop
> +  !$omp parallel do simd collapse(3) lastprivate(k) private(i,j)
> +  do i = 1, n
> +    do j = 1, m, 2
> +      do k = j - 41, p
> +        if (k < 1 - 41 .or. k > p) error stop
> +      end do
> +    end do
> +  end do
> +  if (k /= p + 1) error stop
> +
> +  !$omp parallel do simd collapse(3) lastprivate(k) private(i,j)
> +  do i = 1, n, 2
> +    do j = 1, m
> +      do k = i - 41, p
> +        if (k < 1 - 41 .or. k > p) error stop
> +      end do
> +    end do
> +  end do
> +  if (k /= p + 1) error stop
>
>    !$omp parallel do simd collapse(3) lastprivate(k) private(i,j)
>    do i = 1, n, 2
> @@ -285,27 +282,27 @@ subroutine lastprivate_check_do_simd_1
>
>    ! Same - but with lastprivate(i,j)
>
> -!  !$omp parallel do simd collapse(3) lastprivate(k) lastprivate(i,j)
> -!  do i = 1, n
> -!    do j = 1, m, 2
> -!      do k = j - 41, p
> -!        if (k < 1 - 41 .or. k > p) error stop
> -!      end do
> -!    end do
> -!  end do
> -!  if (k /= p + 1) error stop
> -!  if (i /= n + 1 .or. j /= m + 2) error stop
> -
> -!  !$omp parallel do simd collapse(3) lastprivate(k) lastprivate(i,j)
> -!  do i = 1, n, 2
> -!    do j = 1, m
> -!      do k = i - 41, p
> -!        if (k < 1 - 41 .or. k > p) error stop
> -!      end do
> -!    end do
> -!  end do
> -!  if (k /= p + 1) error stop
> -!  if (i /= n + 2 .or. j /= m + 1) error stop
> +  !$omp parallel do simd collapse(3) lastprivate(k) lastprivate(i,j)
> +  do i = 1, n
> +    do j = 1, m, 2
> +      do k = j - 41, p
> +        if (k < 1 - 41 .or. k > p) error stop
> +      end do
> +    end do
> +  end do
> +  if (k /= p + 1) error stop
> +  if (i /= n + 1 .or. j /= m + 2) error stop
> +
> +  !$omp parallel do simd collapse(3) lastprivate(k) lastprivate(i,j)
> +  do i = 1, n, 2
> +    do j = 1, m
> +      do k = i - 41, p
> +        if (k < 1 - 41 .or. k > p) error stop
> +      end do
> +    end do
> +  end do
> +  if (k /= p + 1) error stop
> +  if (i /= n + 2 .or. j /= m + 1) error stop
>
>    !$omp parallel do simd collapse(3) lastprivate(k) lastprivate(i,j)
>    do i = 1, n, 2
> @@ -343,25 +340,25 @@ subroutine lastprivate_check_do_1
>    ! Use 'i' or 'j', unit step on 'i' or on 'j' -> 4 loops
>    ! Then same, except use non-unit step for 'k'
>
> -!  !$omp parallel do collapse(3) lastprivate(k)
> -!  do i = 1, n
> -!    do j = 1, m, 2
> -!      do k = j - 41, p
> -!        if (k < 1 - 41 .or. k > p) error stop
> -!      end do
> -!    end do
> -!  end do
> -!  if (k /= p + 1) error stop
> -
> -!  !$omp parallel do collapse(3) lastprivate(k)
> -!  do i = 1, n, 2
> -!    do j = 1, m
> -!      do k = i - 41, p
> -!        if (k < 1 - 41 .or. k > p) error stop
> -!      end do
> -!    end do
> -!  end do
> -!  if (k /= p + 1) error stop
> +  !$omp parallel do collapse(3) lastprivate(k)
> +  do i = 1, n
> +    do j = 1, m, 2
> +      do k = j - 41, p
> +        if (k < 1 - 41 .or. k > p) error stop
> +      end do
> +    end do
> +  end do
> +  if (k /= p + 1) error stop
> +
> +  !$omp parallel do collapse(3) lastprivate(k)
> +  do i = 1, n, 2
> +    do j = 1, m
> +      do k = i - 41, p
> +        if (k < 1 - 41 .or. k > p) error stop
> +      end do
> +    end do
> +  end do
> +  if (k /= p + 1) error stop
>
>    !$omp parallel do collapse(3) lastprivate(k)
>    do i = 1, n, 2
> @@ -385,25 +382,25 @@ subroutine lastprivate_check_do_1
>
>    ! Same but 'private' for all (i,j) vars
>
> -!  !$omp parallel do collapse(3) lastprivate(k) private(i,j)
> -!  do i = 1, n
> -!    do j = 1, m, 2
> -!      do k = j - 41, p
> -!        if (k < 1 - 41 .or. k > p) error stop
> -!      end do
> -!    end do
> -!  end do
> -!  if (k /= p + 1) error stop
> -
> -!  !$omp parallel do collapse(3) lastprivate(k) private(i,j)
> -!  do i = 1, n, 2
> -!    do j = 1, m
> -!      do k = i - 41, p
> -!        if (k < 1 - 41 .or. k > p) error stop
> -!      end do
> -!    end do
> -!  end do
> -!  if (k /= p + 1) error stop
> +  !$omp parallel do collapse(3) lastprivate(k) private(i,j)
> +  do i = 1, n
> +    do j = 1, m, 2
> +      do k = j - 41, p
> +        if (k < 1 - 41 .or. k > p) error stop
> +      end do
> +    end do
> +  end do
> +  if (k /= p + 1) error stop
> +
> +  !$omp parallel do collapse(3) lastprivate(k) private(i,j)
> +  do i = 1, n, 2
> +    do j = 1, m
> +      do k = i - 41, p
> +        if (k < 1 - 41 .or. k > p) error stop
> +      end do
> +    end do
> +  end do
> +  if (k /= p + 1) error stop
>
>    !$omp parallel do collapse(3) lastprivate(k) private(i,j)
>    do i = 1, n, 2
> @@ -427,27 +424,27 @@ subroutine lastprivate_check_do_1
>
>    ! Same - but with lastprivate(i,j)
>
> -!  !$omp parallel do collapse(3) lastprivate(k) lastprivate(i,j)
> -!  do i = 1, n
> -!    do j = 1, m, 2
> -!      do k = j - 41, p
> -!        if (k < 1 - 41 .or. k > p) error stop
> -!      end do
> -!    end do
> -!  end do
> -!  if (k /= p + 1) error stop
> -!  if (i /= n + 1 .or. j /= m + 2) error stop
> -
> -!  !$omp parallel do collapse(3) lastprivate(k) lastprivate(i,j)
> -!  do i = 1, n, 2
> -!    do j = 1, m
> -!      do k = i - 41, p
> -!        if (k < 1 - 41 .or. k > p) error stop
> -!      end do
> -!    end do
> -!  end do
> -!  if (k /= p + 1) error stop
> -!  if (i /= n + 2 .or. j /= m + 1) error stop
> +  !$omp parallel do collapse(3) lastprivate(k) lastprivate(i,j)
> +  do i = 1, n
> +    do j = 1, m, 2
> +     do k = j - 41, p
> +        if (k < 1 - 41 .or. k > p) error stop
> +      end do
> +    end do
> +  end do
> +  if (k /= p + 1) error stop
> +  if (i /= n + 1 .or. j /= m + 2) error stop
> +
> +  !$omp parallel do collapse(3) lastprivate(k) lastprivate(i,j)
> +  do i = 1, n, 2
> +    do j = 1, m
> +      do k = i - 41, p
> +        if (k < 1 - 41 .or. k > p) error stop
> +      end do
> +    end do
> +  end do
> +  if (k /= p + 1) error stop
> +  if (i /= n + 2 .or. j /= m + 1) error stop
>
>    !$omp parallel do collapse(3) lastprivate(k) lastprivate(i,j)
>    do i = 1, n, 2
> @@ -481,42 +478,42 @@ subroutine lastprivate_check_2
>    m = 23
>    p = 27
>
> -!  !$omp parallel do simd collapse(3) lastprivate(p)
> -!  do i = 1, n
> -!    do j = 1, m,2
> -!      do k = 1, j + 41
> -!        do ll = 1, p, 2
> -!          if (k > 23 + 41 .or. k < 1) error stop
> -!        end do
> -!      end do
> -!    end do
> -!  end do
> -!  if (ll /= 29) error stop
> -
> -!  !$omp simd collapse(3) lastprivate(p)
> -!  do i = 1, n
> -!    do j = 1, m,2
> -!      do k = 1, j + 41
> -!        do ll = 1, p, 2
> -!          if (k > 23 + 41 .or. k < 1) error stop
> -!        end do
> -!      end do
> -!    end do
> -!  end do
> -!  if (ll /= 29) error stop
> -
> -!  !$omp simd collapse(3) lastprivate(k)
> -!  do i = 1, n,2
> -!    do j = 1, m
> -!      do k = 1, i + 41
> -!        if (k > 11 + 41 .or. k < 1) error stop
> -!      end do
> -!    end do
> -!  end do
> -!if (k /= 53) then
> -!  print *, k, 53
> -!  error stop
> -!endif
> +  !$omp parallel do simd collapse(3) lastprivate(ll)
> +  do i = 1, n
> +    do j = 1, m,2
> +      do k = 1, j + 41
> +        do ll = 1, p, 2
> +          if (k > 23 + 41 .or. k < 1) error stop
> +        end do
> +      end do
> +    end do
> +  end do
> +  if (ll /= 29) error stop
> +
> +  !$omp simd collapse(3) lastprivate(ll)
> +  do i = 1, n
> +    do j = 1, m,2
> +      do k = 1, j + 41
> +        do ll = 1, p, 2
> +          if (k > 23 + 41 .or. k < 1) error stop
> +        end do
> +      end do
> +    end do
> +  end do
> +  if (ll /= 29) error stop
> +
> +  !$omp simd collapse(3) lastprivate(k)
> +  do i = 1, n,2
> +    do j = 1, m
> +      do k = 1, i + 41
> +        if (k > 11 + 41 .or. k < 1) error stop
> +      end do
> +    end do
> +  end do
> +if (k /= 53) then
> +  print *, k, 53
> +  error stop
> +endif
>
>  !$omp simd collapse(3) lastprivate(k)
>  do i = 1, n,2
> @@ -546,32 +543,32 @@ if (k /= 53) then
>  endif
>
>  ! - Same but without 'private':
> -!!$omp simd collapse(3) lastprivate(k)
> -!do i = 1, n
> -!  do j = 1, m,2
> -!    do k = 1, j + 41
> -!      if (k > 23 + 41 .or. k < 1) error stop
> -!    end do
> -!  end do
> -!end do
> -!if (k /= 65) then
> -!  print *, k, 65
> -!  error stop
> -!endif
> -
> -
> -!!$omp simd collapse(3) lastprivate(k)
> -!do i = 1, n,2
> -!  do j = 1, m
> -!    do k = 1, i + 41
> -!      if (k > 11 + 41 .or. k < 1) error stop
> -!    end do
> -!  end do
> -!end do
> -!if (k /= 53) then
> -!  print *, k, 53
> -!  error stop
> -!endif
> +!$omp simd collapse(3) lastprivate(k)
> +do i = 1, n
> +  do j = 1, m,2
> +    do k = 1, j + 41
> +      if (k > 23 + 41 .or. k < 1) error stop
> +    end do
> +  end do
> +end do
> +if (k /= 65) then
> +  print *, k, 65
> +  error stop
> +endif
> +
> +
> +!$omp simd collapse(3) lastprivate(k)
> +do i = 1, n,2
> +  do j = 1, m
> +    do k = 1, i + 41
> +      if (k > 11 + 41 .or. k < 1) error stop
> +    end do
> +  end do
> +end do
> +if (k /= 53) then
> +  print *, k, 53
> +  error stop
> +endif
>
>  !$omp simd collapse(3) lastprivate(k)
>  do i = 1, n,2
> @@ -601,32 +598,32 @@ if (k /= 53) then
>  endif
>
>  ! - all with lastprivate
> -!!$omp simd collapse(3) lastprivate(k) lastprivate(i, j)
> -!do i = 1, n
> -!  do j = 1, m,2
> -!    do k = 1, j + 41
> -!      if (k > 23 + 41 .or. k < 1) error stop
> -!    end do
> -!  end do
> -!end do
> -!if (k /= 65) then
> -!  print *, k, 65
> -!  error stop
> -!endif
> -
> -
> -!!$omp simd collapse(3) lastprivate(k) lastprivate(i, j)
> -!do i = 1, n,2
> -!  do j = 1, m
> -!    do k = 1, i + 41
> -!      if (k > 11 + 41 .or. k < 1) error stop
> -!    end do
> -!  end do
> -!end do
> -!if (k /= 53) then
> -!  print *, k, 53
> -!  error stop
> -!endif
> +!$omp simd collapse(3) lastprivate(k) lastprivate(i, j)
> +do i = 1, n
> +  do j = 1, m,2
> +    do k = 1, j + 41
> +      if (k > 23 + 41 .or. k < 1) error stop
> +    end do
> +  end do
> +end do
> +if (k /= 65) then
> +  print *, k, 65
> +  error stop
> +endif
> +
> +
> +!$omp simd collapse(3) lastprivate(k) lastprivate(i, j)
> +do i = 1, n,2
> +  do j = 1, m
> +    do k = 1, i + 41
> +      if (k > 11 + 41 .or. k < 1) error stop
> +    end do
> +  end do
> +end do
> +if (k /= 53) then
> +  print *, k, 53
> +  error stop
> +endif
>
>  !$omp simd collapse(3) lastprivate(k) lastprivate(i, j)
>  do i = 1, n,2
> diff --git a/libgomp/testsuite/libgomp.fortran/non-rectangular-loop-1a.f90 b/libgomp/testsuite/libgomp.fortran/non-rectangular-loop-1a.f90
> deleted file mode 100644
> index 77aa887942e..00000000000
> --- a/libgomp/testsuite/libgomp.fortran/non-rectangular-loop-1a.f90
> +++ /dev/null
> @@ -1,374 +0,0 @@
> -! { dg-do compile }
> -! { dg-additional-options "-msse2" { target sse2_runtime } }
> -! { dg-additional-options "-mavx" { target avx_runtime } }
> -
> -! PR fortran/107424
> -
> -! Nonrectangular loop nests checks
> -
> -! ========================================================
> -! NOTE: The testcases are from non-rectangular-loop-1.f90,
> -! but commented there. Feel free to remove this
> -! file + uncomment them in non-rectangular-loop-1.f90
> -! Otherwise, you need to change it to 'dg-do run'!
> -! ========================================================
> -
> -module m
> -  implicit none (type, external)
> -contains
> -
> -! The 'k' loop uses i or j as start value
> -! but a constant end value such that 'lastprivate'
> -! should be well-defined
> -subroutine lastprivate_check_simd_1
> -  integer :: n,m,p, i,j,k
> -
> -  n = 11
> -  m = 23
> -  p = 27
> -
> -  ! Use 'i' or 'j', unit step on 'i' or on 'j' -> 4 loops
> -  ! Then same, except use non-unit step for 'k'
> -
> -  !$omp simd collapse(3) lastprivate(k)
> -  do i = 1, n
> -    do j = 1, m, 2  ! { dg-message "sorry, unimplemented: non-rectangular loop nest with step other than constant 1 or -1 for 'j'" }
> -      do k = j - 41, p  ! { dg-note "Used here" }
> -        if (k < 1 - 41 .or. k > p) error stop
> -      end do
> -    end do
> -  end do
> -  if (k /= p + 1) error stop
> -
> -  !$omp simd collapse(3) lastprivate(k)
> -  do i = 1, n, 2  ! { dg-message "sorry, unimplemented: non-rectangular loop nest with step other than constant 1 or -1 for 'i'" }
> -    do j = 1, m
> -      do k = i - 41, p  ! { dg-note "Used here" }
> -        if (k < 1 - 41 .or. k > p) error stop
> -      end do
> -    end do
> -  end do
> -  if (k /= p + 1) error stop
> -
> -  ! Same but 'private' for all (i,j) vars
> -
> -  !$omp simd collapse(3) lastprivate(k) private(i,j)
> -  do i = 1, n
> -    do j = 1, m, 2  ! { dg-message "sorry, unimplemented: non-rectangular loop nest with step other than constant 1 or -1 for 'j'" }
> -      do k = j - 41, p  ! { dg-note "Used here" }
> -        if (k < 1 - 41 .or. k > p) error stop
> -      end do
> -    end do
> -  end do
> -  if (k /= p + 1) error stop
> -
> -  !$omp simd collapse(3) lastprivate(k) private(i,j)
> -  do i = 1, n, 2  ! { dg-message "sorry, unimplemented: non-rectangular loop nest with step other than constant 1 or -1 for 'i'" }
> -    do j = 1, m
> -      do k = i - 41, p  ! { dg-note "Used here" }
> -        if (k < 1 - 41 .or. k > p) error stop
> -      end do
> -    end do
> -  end do
> -  if (k /= p + 1) error stop
> -
> -  ! Same - but with lastprivate(i,j)
> -
> -  !$omp simd collapse(3) lastprivate(k) lastprivate(i,j)
> -  do i = 1, n
> -    do j = 1, m, 2  ! { dg-message "sorry, unimplemented: non-rectangular loop nest with step other than constant 1 or -1 for 'j'" }
> -      do k = j - 41, p  ! { dg-note "Used here" }
> -        if (k < 1 - 41 .or. k > p) error stop
> -      end do
> -    end do
> -  end do
> -  if (k /= p + 1) error stop
> -  if (i /= n + 1 .or. j /= m + 2) error stop
> -
> -  !$omp simd collapse(3) lastprivate(k) lastprivate(i,j)
> -  do i = 1, n, 2  ! { dg-message "sorry, unimplemented: non-rectangular loop nest with step other than constant 1 or -1 for 'i'" }
> -    do j = 1, m
> -      do k = i - 41, p  ! { dg-note "Used here" }
> -        if (k < 1 - 41 .or. k > p) error stop
> -      end do
> -    end do
> -  end do
> -  if (k /= p + 1) error stop
> -  if (i /= n + 2 .or. j /= m + 1) error stop
> -
> -end subroutine lastprivate_check_simd_1
> -
> -
> -! Same but with do simd
> -subroutine lastprivate_check_do_simd_1
> -  integer :: n,m,p, i,j,k
> -
> -  n = 11
> -  m = 23
> -  p = 27
> -
> -  ! Use 'i' or 'j', unit step on 'i' or on 'j' -> 4 loops
> -  ! Then same, except use non-unit step for 'k'
> -
> -  !$omp parallel do simd collapse(3) lastprivate(k)
> -  do i = 1, n
> -    do j = 1, m, 2  ! { dg-message "sorry, unimplemented: non-rectangular loop nest with step other than constant 1 or -1 for 'j'" }
> -      do k = j - 41, p  ! { dg-note "Used here" }
> -        if (k < 1 - 41 .or. k > p) error stop
> -      end do
> -    end do
> -  end do
> -  if (k /= p + 1) error stop
> -
> -  !$omp parallel do simd collapse(3) lastprivate(k)
> -  do i = 1, n, 2  ! { dg-message "sorry, unimplemented: non-rectangular loop nest with step other than constant 1 or -1 for 'i'" }
> -    do j = 1, m
> -      do k = i - 41, p  ! { dg-note "Used here" }
> -        if (k < 1 - 41 .or. k > p) error stop
> -      end do
> -    end do
> -  end do
> -  if (k /= p + 1) error stop
> -
> -  ! Same but 'private' for all (i,j) vars
> -
> -  !$omp parallel do simd collapse(3) lastprivate(k) private(i,j)
> -  do i = 1, n
> -    do j = 1, m, 2  ! { dg-message "sorry, unimplemented: non-rectangular loop nest with step other than constant 1 or -1 for 'j'" }
> -      do k = j - 41, p  ! { dg-note "Used here" }
> -        if (k < 1 - 41 .or. k > p) error stop
> -      end do
> -    end do
> -  end do
> -  if (k /= p + 1) error stop
> -
> -  !$omp parallel do simd collapse(3) lastprivate(k) private(i,j)
> -  do i = 1, n, 2  ! { dg-message "sorry, unimplemented: non-rectangular loop nest with step other than constant 1 or -1 for 'i'" }
> -    do j = 1, m
> -      do k = i - 41, p  ! { dg-note "Used here" }
> -        if (k < 1 - 41 .or. k > p) error stop
> -      end do
> -    end do
> -  end do
> -  if (k /= p + 1) error stop
> -
> -  ! Same - but with lastprivate(i,j)
> -
> -  !$omp parallel do simd collapse(3) lastprivate(k) lastprivate(i,j)
> -  do i = 1, n
> -    do j = 1, m, 2  ! { dg-message "sorry, unimplemented: non-rectangular loop nest with step other than constant 1 or -1 for 'j'" }
> -      do k = j - 41, p  ! { dg-note "Used here" }
> -        if (k < 1 - 41 .or. k > p) error stop
> -      end do
> -    end do
> -  end do
> -  if (k /= p + 1) error stop
> -  if (i /= n + 1 .or. j /= m + 2) error stop
> -
> -  !$omp parallel do simd collapse(3) lastprivate(k) lastprivate(i,j)
> -  do i = 1, n, 2  ! { dg-message "sorry, unimplemented: non-rectangular loop nest with step other than constant 1 or -1 for 'i'" }
> -    do j = 1, m
> -      do k = i - 41, p  ! { dg-note "Used here" }
> -        if (k < 1 - 41 .or. k > p) error stop
> -      end do
> -    end do
> -  end do
> -  if (k /= p + 1) error stop
> -  if (i /= n + 2 .or. j /= m + 1) error stop
> -
> -end subroutine lastprivate_check_do_simd_1
> -
> -
> -
> -! Same but with do
> -subroutine lastprivate_check_do_1
> -  integer :: n,m,p, i,j,k
> -
> -  n = 11
> -  m = 23
> -  p = 27
> -
> -  ! Use 'i' or 'j', unit step on 'i' or on 'j' -> 4 loops
> -  ! Then same, except use non-unit step for 'k'
> -
> -  !$omp parallel do collapse(3) lastprivate(k)
> -  do i = 1, n
> -    do j = 1, m, 2  ! { dg-message "sorry, unimplemented: non-rectangular loop nest with step other than constant 1 or -1 for 'j'" }
> -      do k = j - 41, p  ! { dg-note "Used here" }
> -        if (k < 1 - 41 .or. k > p) error stop
> -      end do
> -    end do
> -  end do
> -  if (k /= p + 1) error stop
> -
> -  !$omp parallel do collapse(3) lastprivate(k)
> -  do i = 1, n, 2  ! { dg-message "sorry, unimplemented: non-rectangular loop nest with step other than constant 1 or -1 for 'i'" }
> -    do j = 1, m
> -      do k = i - 41, p  ! { dg-note "Used here" }
> -        if (k < 1 - 41 .or. k > p) error stop
> -      end do
> -    end do
> -  end do
> -  if (k /= p + 1) error stop
> -
> -  ! Same but 'private' for all (i,j) vars
> -
> -  !$omp parallel do collapse(3) lastprivate(k) private(i,j)
> -  do i = 1, n
> -    do j = 1, m, 2  ! { dg-message "sorry, unimplemented: non-rectangular loop nest with step other than constant 1 or -1 for 'j'" }
> -      do k = j - 41, p  ! { dg-note "Used here" }
> -        if (k < 1 - 41 .or. k > p) error stop
> -      end do
> -    end do
> -  end do
> -  if (k /= p + 1) error stop
> -
> -  !$omp parallel do collapse(3) lastprivate(k) private(i,j)
> -  do i = 1, n, 2  ! { dg-message "sorry, unimplemented: non-rectangular loop nest with step other than constant 1 or -1 for 'i'" }
> -    do j = 1, m
> -      do k = i - 41, p  ! { dg-note "Used here" }
> -        if (k < 1 - 41 .or. k > p) error stop
> -      end do
> -    end do
> -  end do
> -  if (k /= p + 1) error stop
> -
> -  ! Same - but with lastprivate(i,j)
> -
> -  !$omp parallel do collapse(3) lastprivate(k) lastprivate(i,j)
> -  do i = 1, n
> -    do j = 1, m, 2  ! { dg-message "sorry, unimplemented: non-rectangular loop nest with step other than constant 1 or -1 for 'j'" }
> -      do k = j - 41, p  ! { dg-note "Used here" }
> -        if (k < 1 - 41 .or. k > p) error stop
> -      end do
> -    end do
> -  end do
> -  if (k /= p + 1) error stop
> -  if (i /= n + 1 .or. j /= m + 2) error stop
> -
> -  !$omp parallel do collapse(3) lastprivate(k) lastprivate(i,j)
> -  do i = 1, n, 2  ! { dg-message "sorry, unimplemented: non-rectangular loop nest with step other than constant 1 or -1 for 'i'" }
> -    do j = 1, m
> -      do k = i - 41, p  ! { dg-note "Used here" }
> -        if (k < 1 - 41 .or. k > p) error stop
> -      end do
> -    end do
> -  end do
> -  if (k /= p + 1) error stop
> -  if (i /= n + 2 .or. j /= m + 1) error stop
> -
> -end subroutine lastprivate_check_do_1
> -
> -
> -
> -subroutine lastprivate_check_2
> -  integer :: n,m,p, i,j,k,ll
> -
> -  n = 11
> -  m = 23
> -  p = 27
> -
> -  !$omp parallel do simd collapse(3) lastprivate(p)
> -  do i = 1, n
> -    do j = 1, m,2  ! { dg-message "sorry, unimplemented: non-rectangular loop nest with step other than constant 1 or -1 for 'j'" }
> -      do k = 1, j + 41  ! { dg-note "Used here" }
> -        do ll = 1, p, 2
> -          if (k > 23 + 41 .or. k < 1) error stop
> -        end do
> -      end do
> -    end do
> -  end do
> -  if (ll /= 29) error stop
> -
> -  !$omp simd collapse(3) lastprivate(p)
> -  do i = 1, n
> -    do j = 1, m,2  ! { dg-message "sorry, unimplemented: non-rectangular loop nest with step other than constant 1 or -1 for 'j'" }
> -      do k = 1, j + 41  ! { dg-note "Used here" }
> -        do ll = 1, p, 2
> -          if (k > 23 + 41 .or. k < 1) error stop
> -        end do
> -      end do
> -    end do
> -  end do
> -  if (ll /= 29) error stop
> -
> -  !$omp simd collapse(3) lastprivate(k)
> -  do i = 1, n,2  ! { dg-message "sorry, unimplemented: non-rectangular loop nest with step other than constant 1 or -1 for 'i'" }
> -    do j = 1, m
> -      do k = 1, i + 41  ! { dg-note "Used here" }
> -        if (k > 11 + 41 .or. k < 1) error stop
> -      end do
> -    end do
> -  end do
> -if (k /= 53) then
> -  print *, k, 53
> -  error stop
> -endif
> -
> -! - Same but without 'private':
> -!$omp simd collapse(3) lastprivate(k)
> -do i = 1, n
> -  do j = 1, m,2  ! { dg-message "sorry, unimplemented: non-rectangular loop nest with step other than constant 1 or -1 for 'j'" }
> -    do k = 1, j + 41  ! { dg-note "Used here" }
> -      if (k > 23 + 41 .or. k < 1) error stop
> -    end do
> -  end do
> -end do
> -if (k /= 65) then
> -  print *, k, 65
> -  error stop
> -endif
> -
> -
> -!$omp simd collapse(3) lastprivate(k)
> -do i = 1, n,2  ! { dg-message "sorry, unimplemented: non-rectangular loop nest with step other than constant 1 or -1 for 'i'" }
> -  do j = 1, m
> -    do k = 1, i + 41  ! { dg-note "Used here" }
> -      if (k > 11 + 41 .or. k < 1) error stop
> -    end do
> -  end do
> -end do
> -if (k /= 53) then
> -  print *, k, 53
> -  error stop
> -endif
> -
> -! - all with lastprivate
> -!$omp simd collapse(3) lastprivate(k) lastprivate(i, j)
> -do i = 1, n
> -  do j = 1, m,2  ! { dg-message "sorry, unimplemented: non-rectangular loop nest with step other than constant 1 or -1 for 'j'" }
> -    do k = 1, j + 41  ! { dg-note "Used here" }
> -      if (k > 23 + 41 .or. k < 1) error stop
> -    end do
> -  end do
> -end do
> -if (k /= 65) then
> -  print *, k, 65
> -  error stop
> -endif
> -
> -
> -!$omp simd collapse(3) lastprivate(k) lastprivate(i, j)
> -do i = 1, n,2  ! { dg-message "sorry, unimplemented: non-rectangular loop nest with step other than constant 1 or -1 for 'i'" }
> -  do j = 1, m
> -    do k = 1, i + 41  ! { dg-note "Used here" }
> -      if (k > 11 + 41 .or. k < 1) error stop
> -    end do
> -  end do
> -end do
> -if (k /= 53) then
> -  print *, k, 53
> -  error stop
> -endif
> -
> -end
> -end module m
> -
> -program main
> -  use m
> -  implicit none (type, external)
> -  call lastprivate_check_simd_1
> -  call lastprivate_check_do_simd_1
> -  call lastprivate_check_do_1
> -  call lastprivate_check_2
> -end
> diff --git a/libgomp/testsuite/libgomp.fortran/non-rectangular-loop-5.f90 b/libgomp/testsuite/libgomp.fortran/non-rectangular-loop-5.f90
> index 643ab796a84..0e251f263c8 100644
> --- a/libgomp/testsuite/libgomp.fortran/non-rectangular-loop-5.f90
> +++ b/libgomp/testsuite/libgomp.fortran/non-rectangular-loop-5.f90
> @@ -2,27 +2,41 @@
>  ! { dg-additional-options "-msse2" { target sse2_runtime } }
>  ! { dg-additional-options "-mavx" { target avx_runtime } }
>
> -! PR fortran/107424
> +! PR fortran/107424 - original PR
> +! PR fortran/110735 - PR to implement the feature below
>
>  ! Nonrectangular loop nests checks
>
> +integer :: step
> +step = -1
>  !$omp simd collapse(2)
>  do i = 1, 10
> -  do j = i, 10, 2  ! { dg-message "sorry, unimplemented: non-rectangular loop nest with step other than constant 1 or -1 for 'j'" }
> +  do j = i, 10, step  ! { dg-message "sorry, unimplemented: non-rectangular loop nest with non-constant step for 'j'" }
>    end do
>  end do
>
> +step = 3
>  !$omp do collapse(2) lastprivate(j)  ! { dg-error "lastprivate variable 'j' is private in outer context" }
>  do i = 1, 10
> -  do j = i, 10, 2  ! { dg-message "sorry, unimplemented: non-rectangular loop nest with step other than constant 1 or -1 for 'j'" }
> +  do j = i, 10, step  ! { dg-message "sorry, unimplemented: non-rectangular loop nest with non-constant step for 'j'" }
>    end do
>  end do
>  if (i /= 11) stop 1
>
> +step = -5
>  !$omp simd collapse(2) lastprivate(j)
>  do i = 1, 10
> -  do j = i, 10, 2  ! { dg-message "sorry, unimplemented: non-rectangular loop nest with step other than constant 1 or -1 for 'j'" }
> +  do j = i, 10, step  ! { dg-message "sorry, unimplemented: non-rectangular loop nest with non-constant step for 'j'" }
>    end do
>  end do
>  if (i /= 11) stop 1
> +
> +step = -5
> +!$omp simd collapse(2)
> +do i = 1, 10, step  ! { dg-message "sorry, unimplemented: non-rectangular loop nest with non-constant step for 'i'" }
> +  do j = i, i       ! { dg-note "Used here" }
> +  end do
> +end do
> +if (i /= 11) stop 1
> +
>  end
> diff --git a/libgomp/testsuite/libgomp.fortran/non-rectangular-loop-6.f90 b/libgomp/testsuite/libgomp.fortran/non-rectangular-loop-6.f90
> new file mode 100644
> index 00000000000..ae885af9623
> --- /dev/null
> +++ b/libgomp/testsuite/libgomp.fortran/non-rectangular-loop-6.f90
> @@ -0,0 +1,196 @@
> +! { dg-do run }
> +! { dg-additional-options "-msse2" { target sse2_runtime } }
> +! { dg-additional-options "-mavx" { target avx_runtime } }
> +
> +! PR fortran/107424
> +
> +! Nonrectangular loop nests checks
> +! This testcase uses negative step sizes
> +
> +module m
> +  implicit none (type, external)
> +contains
> +
> +! The 'k' loop uses i or j as start value
> +! but a constant end value such that 'lastprivate'
> +! should be well-defined
> +subroutine lastprivate_check_simd_1
> +  integer :: n,m,p, i,j,k, one
> +
> +  n = 11
> +  m = 23
> +  p = 27
> +  one = 1
> +
> +  ! Use 'i' or 'j', unit step on 'i' or on 'j' -> 4 loops
> +  ! Then same, except use non-unit step for 'k'
> +
> +  !$omp simd collapse(3) lastprivate(k)
> +  do i = n, one, -1
> +    do j = m, one, -2
> +      do k = p + j, p - 41, -1
> +        if (k < p - 41 .or. k > p+m) error stop
> +      end do
> +    end do
> +  end do
> +  if (k /= p - 41 - 1) error stop
> +
> +  !$omp simd collapse(3) lastprivate(k)
> +  do i = n, 1, -2
> +    do j = m, 1, -1
> +      do k = p, i - 41, -1
> +        if (k < 1 - 41 .or. k > p) error stop
> +      end do
> +    end do
> +  end do
> +  if (k /= -41) error stop
> +
> +  !$omp simd collapse(3) lastprivate(k)
> +  do i = n, one, -2
> +    do j = m, one, -1
> +      do k = p, j - 41, -1
> +        if (k < 1 - 41 .or. k > p) then
> +          ! print *, i, j, k,p, " -> i, j, k, p   (k < 1 - 41 .or. k > p)"
> +          error stop
> +        end if
> +      end do
> +    end do
> +  end do
> +  if (k /= -41) error stop
> +
> +  k = -43
> +  m = 0
> +  !$omp simd collapse(3) lastprivate(k)
> +  do i = m, one, -2
> +    do j = m, one, -1
> +      do k = p, j - 41, -1
> +        if (k < 1 - 41 .or. k > p) then
> +          ! print *, i, j, k,p, " -> i, j, k, p   (k < 1 - 41 .or. k > p)"
> +          error stop
> +        end if
> +      end do
> +    end do
> +  end do
> +  if (k /= -43) error stop
> +
> +  m = 23
> +
> +  !$omp simd collapse(3) lastprivate(k)
> +  do i = n, one, -1
> +    do j = m, one, -2
> +      do k = p, i - 41, -1
> +        if (k < 1 - 41 .or. k > p) error stop
> +      end do
> +    end do
> +  end do
> +  if (k /= -41) error stop
> +
> +  n = -5
> +  k = - 70
> +  !$omp simd collapse(3) lastprivate(k)
> +  do i = n, one, -1
> +    do j = m, one, -2
> +      do k = p, i - 41, -1
> +        if (k < 1 - 41 .or. k > p) error stop
> +      end do
> +    end do
> +  end do
> +  if (k /= -70) error stop
> +
> +  n = 11
> +
> +  ! Same but 'private' for all (i,j) vars
> +
> +  !$omp simd collapse(3) lastprivate(k) private(i,j)
> +  do i = n, one, -1
> +    do j = m, one, -2
> +      do k = p, j - 41, -1
> +        if (k < 1 - 41 .or. k > p) error stop
> +      end do
> +    end do
> +  end do
> +  if (k /= -41) error stop
> +
> +  !$omp simd collapse(3) lastprivate(k) private(i,j)
> +  do i = n, one, -2
> +    do j = m, one, -1
> +      do k = p, i - 41, -1
> +        if (k < 1 - 41 .or. k > p) error stop
> +      end do
> +    end do
> +  end do
> +  if (k /= -41) error stop
> +
> +  !$omp simd collapse(3) lastprivate(k) private(i,j)
> +  do i = n, one, -2
> +    do j = m, one, -1
> +      do k = p, j - 41, -1
> +        if (k < 1 - 41 .or. k > p) error stop
> +      end do
> +    end do
> +  end do
> +  if (k /= -41) error stop
> +
> +  !$omp simd collapse(3) lastprivate(k) private(i,j)
> +  do i = n, one, -1
> +    do j = m, one, -2
> +      do k = p, i - 41, -1
> +        if (k < 1 - 41 .or. k > p) error stop
> +      end do
> +    end do
> +  end do
> +  if (k /= -41) error stop
> +
> +  ! Same - but with lastprivate(i,j)
> +
> +  !$omp simd collapse(3) lastprivate(k) lastprivate(i,j)
> +  do i = n, one, -1
> +    do j = m, one, -2
> +      do k = p, j - 41, -1
> +        if (k < 1 - 41 .or. k > p) error stop
> +      end do
> +    end do
> +  end do
> +  if (k /= -41) error stop
> +  if (i /= 0 .or. j /= -1) error stop
> +
> +  !$omp simd collapse(3) lastprivate(k) lastprivate(i,j)
> +  do i = n, 1, -2
> +    do j = m, one, -1
> +      do k = p, i - 41, -1
> +        if (k < 1 - 41 .or. k > p) error stop
> +      end do
> +    end do
> +  end do
> +  if (k /= -41) error stop
> +  if (i /= -1 .or. j /= 0) error stop
> +
> +  !$omp simd collapse(3) lastprivate(k) lastprivate(i,j)
> +  do i = n, 1, -2
> +    do j = m, 1, -1
> +      do k = p, j - 41, -1
> +        if (k < 1 - 41 .or. k > p) error stop
> +      end do
> +    end do
> +  end do
> +  if (k /= -41) error stop
> +  if (i /= -1 .or. j /= 0) error stop
> +
> +  !$omp simd collapse(3) lastprivate(k) lastprivate(i,j)
> +  do i = n, one, -1
> +    do j = m, one, -2
> +      do k = p, i - 41, -1
> +        if (k < 1 - 41 .or. k > p) error stop
> +      end do
> +    end do
> +  end do
> +  if (k /= -41) error stop
> +  if (i /= 0 .or. j /= -1) error stop
> +end subroutine lastprivate_check_simd_1
> +end module m
> +
> +program main
> +  use m
> +  implicit none (type, external)
> +  call lastprivate_check_simd_1
> +end
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