The RANGE Directive

 

The RANGE attribute is used to restrict the possible distribution formats for an object or template that has the DYNAMIC attribute or a transcriptive distribution format (including pointers).

H811 range-directive	is RANGE ranger range-attr-stuff
H812 ranger	is object-name or template-name
H813 range-attr-stuff	is range-distribution-list
H814 range-distribution	is ( range-attr-list )
H815 range-attr	is range-dist-format or ALL
H816 range-dist-format	is BLOCK [ ( ) ] or CYCLIC [ ( ) ] or GEN_BLOCK or INDIRECT or *

• At least one of the following must be true:
  • The ranger has the DYNAMIC attribute.
  • The ranger has the INHERIT attribute.
  • The ranger is specified with a dist-format-clause of * in a DISTRIBUTE or combined directive.
• The length of each range-attr-list must be equal to the rank of the ranger.
• The ranger must not appear as an alignee in an ALIGN or REALIGN directive.

Since the length of each range-attr-list is the same as the rank of the ranger, each range-attr, R, in each range-distribution corresponds positionally to a dimension D of the ranger. This dimension D in turn either corresponds (though not necessarily positionally) to an axis A of the template with which the ranger is ultimately aligned, or corresponds to no axis in that template.

With this notation, a RANGE attribute on a ranger is equivalent to the following restriction:

For at least one range-distribution in the range-distribution-list, every range-attr, R, must either

• be compatible with the distribution format of the corresponding axis A, if such a corresponding axis exists, or
• be either * or ALL, if no such corresponding axis exists.

This compatibility must be maintained by any DISTRIBUTE or REDISTRIBUTE directive in which the ranger appears as a distributee, or if the ranger has the POINTER attribute and is transcriptively distributed, for any target with which the ranger becomes associated.

A distribution format of

1. BLOCK is compatible with a range-dist-format of BLOCK, BLOCK() or CYCLIC();
2. BLOCK(n) is compatible with a range-dist-format of BLOCK(), or CYCLIC();
3. CYCLIC is compatible with a range-dist-format of CYCLIC or CYCLIC();
4. CYCLIC(n) is compatible with a range-dist-format of CYCLIC();
5. GEN_BLOCK(a) is compatible with a range-dist-format of GEN_BLOCK;
6. INDIRECT(a) is compatible with a range-dist-format of INDIRECT;
7. * is compatible with a range-dist-format of *.

All distribution formats are compatible with a range-dist-format of ALL.

Note that the possibility of a RANGE directive of the form

!HPF$ RANGE range-attr-stuff-list :: ranger-list

is covered by syntax rule H301 for a combined-directive using combined-attribute-extended as defined in rule H801.

!HPF$    DISTRIBUTE T(BLOCK)
!HPF$    ALIGN A(I,J) WITH T(I)

         CALL SUB(A)
            ....

         SUBROUTINE SUB(X)
!HPF$    INHERIT X
!HPF$    RANGE X (BLOCK, *), (CYCLIC, *)

Since the ultimate align target of X, the inherited template T in this case, does not have a second dimension, only a * or ALL can be used in the second dimension of each range-distribution on for X.

         REAL A(100, 100, 100)
!HPF$    DISTRIBUTE A(BLOCK, *, CYCLIC)

         CALL SUB( A(:,:,1) )          ! Conforming
         CALL SUB( A(:,1,:) )          ! Nonconforming
         CALL SUB( A(1,:,:) )          ! Nonconforming
            ....

         SUBROUTINE SUB(X)
         REAL X(:, :)
!HPF$    INHERIT X
!HPF$    RANGE X (BLOCK, *)

Given the range directive in the subroutine SUB, only the first call to SUB is conforming. However, all three calls can be made conforming if the range directive above is replaced by the following directive:

!HPF$    RANGE (BLOCK, *), (BLOCK, CYCLIC), (*, CYCLIC) :: X