6.6. Array Sections in Device Constructs

The following examples show the usage of array sections in map clauses on target and target data constructs.

This example shows the invalid usage of two separate sections of the same array inside of a target construct.

//%compiler: clang
//%cflags: -fopenmp

/*
* name: array_sections.1
* type: C
* version: omp_4.0
*/
void foo ()
{
   int A[30];
#pragma omp target data map( A[0:4] )
{
   /* Cannot map distinct parts of the same array */
   #pragma omp target map( A[7:20] )
   {
      A[2] = 0;
   }
}
}

!!%compiler: gfortran
!!%cflags: -fopenmp

! name: array_sections.1
! type: F-free
! version: omp_4.0
subroutine foo()
integer :: A(30)
   A = 1
   !$omp target data map( A(1:4) )
     ! Cannot map distinct parts of the same array
     !$omp target map( A(8:27) )
        A(3) = 0
     !$omp end target
   !$omp end target data
end subroutine

This example shows the invalid usage of two separate sections of the same array inside of a target construct.

//%compiler: clang
//%cflags: -fopenmp

/*
* name: array_sections.2
* type: C
* version: omp_4.0
*/
void foo ()
{
   int A[30], *p;
#pragma omp target data map( A[0:4] )
{
   p = &A[0];
   /* invalid because p[3] and A[3] are the same
    * location on the host but the array section
    * specified via p[...] is not a subset of A[0:4] */
   #pragma omp target map( p[3:20] )
   {
      A[2] = 0;
      p[8] = 0;
   }
}
}

!!%compiler: gfortran
!!%cflags: -fopenmp

! name: array_sections.2
! type: F-free
! version: omp_4.0
subroutine foo()
integer,target  :: A(30)
integer,pointer :: p(:)
   A=1
   !$omp target data map( A(1:4) )
     p=>A
     ! invalid because p(4) and A(4) are the same
     ! location on the host but the array section
     ! specified via p(...) is not a subset of A(1:4)
     !$omp target map( p(4:23) )
        A(3) = 0
        p(9) = 0
     !$omp end target
   !$omp end target data
end subroutine

This example shows the valid usage of two separate sections of the same array inside of a target construct.

//%compiler: clang
//%cflags: -fopenmp

/*
* name: array_sections.3
* type: C
* version: omp_4.0
*/
void foo ()
{
   int A[30], *p;
#pragma omp target data map( A[0:4] )
{
   p = &A[0];
   #pragma omp target map( p[7:20] )
   {
      A[2] = 0;
      p[8] = 0;
   }
}
}

!!%compiler: gfortran
!!%cflags: -fopenmp

! name: array_sections.3
! type: F-free
! version: omp_4.0
subroutine foo()
integer,target  :: A(30)
integer,pointer :: p(:)
   !$omp target data map( A(1:4) )
     p=>A
     !$omp target map( p(8:27) )
        A(3) = 0
        p(9) = 0
     !$omp end target
   !$omp end target data
end subroutine

This example shows the valid usage of a wholly contained array section of an already mapped array section inside of a target construct.

//%compiler: clang
//%cflags: -fopenmp

/*
* name: array_sections.4
* type: C
* version: omp_4.0
*/
void foo ()
{
   int A[30], *p;
#pragma omp target data map( A[0:10] )
{
   p = &A[0];
   #pragma omp target map( p[3:7] )
   {
      A[2] = 0;
      p[8] = 0;
      A[8] = 1;
   }
}
}

!!%compiler: gfortran
!!%cflags: -fopenmp

! name: array_sections.4
! type: F-free
! version: omp_4.0
subroutine foo()
integer,target  :: A(30)
integer,pointer :: p(:)
   !$omp target data map( A(1:10) )
     p=>A
     !$omp target map( p(4:10) )
        A(3) = 0
        p(9) = 0
        A(9) = 1
     !$omp end target
   !$omp end target data
end subroutine