Array Arguments Example 2

It is much simpler but less efficient to use prescriptive distributions.

Unless the HPF compiler is really smart, the following rewrite of Zubbie, using prescriptive distribution directives, will generate two remappings. What will probably happen is that the compiler will remap the dummy arguments so that they are distributed (BLOCK,BLOCK).

     SUBROUTINE Zubbie(x,y,z)
!HPF$ TEMPLATE, DIMENSION(4,6)            :: T
!HPF$ PROCESSORS, DIMENSION(2,2)          :: P
      REAL, INTENT(INOUT), DIMENSION(:,:) :: x, y
      REAL, INTENT(INOUT), DIMENSION(:,:) :: z
!HPF$ DISTRIBUTE (BLOCK,BLOCK) ONTO P     :: x, y, z
      ...

This will give the following distribution:

• P(1,1) owns X(1:2,1:2) and so on,
• P(2,1) owns X(3,1:2) and so on,
• P(1,2) owns X(1:2,3) and so on,
• P(2,2) owns X(3,3) and so on,

This means that all three arguments are remapped on entry and on exit which will be very inefficient.