Explicit Shadow
Shadow in HPF
- Shadow elements are not really visible to the programmer, and are managed completely by the compiler.
Explicit shadow in JAHPF
- The communication for the SHADOW area can be controlled by REFLECT, EXT_HOME and LOCAL.
Example
!HPF$ DISTRIBUTE A(BLOCK)
!HPF$ SHADOW A(1)
!HPF$ INDEPENDENT
DO J=...
!HPF$ ON EXT_HOME(A(J)) ! Two processors may own.
A(J) = func(J) ! Redundant computation
ENDDO