[Bug libgomp/94635] New: [OpenMP][Offloading] mapping with alloc/delete followed by map(from/fromto fails

[burnus at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94635

            Bug ID: 94635
           Summary: [OpenMP][Offloading] mapping with alloc/delete
                    followed by map(from/fromto  fails
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Keywords: openmp, wrong-code
          Severity: normal
          Priority: P3
         Component: libgomp
          Assignee: unassigned at gcc dot gnu.org
          Reporter: burnus at gcc dot gnu.org
                CC: jakub at gcc dot gnu.org
  Target Milestone: ---

Based on an OpenMP test case from SOLLVE_VV,
   https://github.com/SOLLVE/sollve_vv/
Namely, based on
  tests/4.5/target_enter_exit_data/
    test_target_enter_exit_data_allocate_array_alloc_delete.F90

The following test case works if one comments:
  !$omp target enter data map(alloc: my1DPtr(:))
  !$omp target exit data map(delete: my1DPtr(:))
Then it prints the expected
  42 …
  10 …
  10 …
  20 …

If one comments only the "map(delete:…)", it prints
  42 …
  10 …
  0 …   (should be: 10)
  10 …  (should be: 20)

And with alloc/delete enabled, it prints:
  42 …
  10 …
  20 20 … 31911936 17 31907872 17 31907952 (should be: 10)
  10 …  (should be: 20)

In the 'target': when using "my1DArr = 99", the garbage values are replaced by
99, i.e.  20 20 … 99 99 …  (twelf times 20 followed by eight times 99).

The testsuite first tests whether alloc/delete works – which does; only
re-using the alloc/delete space fails.


Test case:
----------
  implicit none
  INTEGER, PARAMETER :: N = 20
  INTEGER, ALLOCATABLE, DIMENSION(:) :: my1DPtr
  INTEGER, DIMENSION(N) :: my1DArr

  allocate(my1DPtr(N))

  !$omp target enter data map(alloc: my1DPtr(:))
  !$omp target exit data map(delete: my1DPtr(:))

  my1DPtr(:) = 10
  my1DArr = 42
  print *, my1DArr  ! = 42, okay
  print *, my1DPtr  ! = 10, okay

  !$omp target map(from: my1DArr) map(tofrom: my1DPtr(:))
    my1DArr = my1DPtr
    my1DPtr(:) = 20
  !$omp end target

  print *, my1DArr ! should be: 10 (not 0 or 20+garbage)
  print *, my1DPtr ! should be: 20 (and not 10)
END