Subset HPF

The Fortran 90 features that we shall study are:

• FORTRAN 77,
• array syntax (including WHERE),
• allocatable arrays,
• most Fortran 90 intrinsics,
• take care with storage and sequence association and pointers!

Initially a Subset language was defined to provide a `fast-track' for useful, yet basic, implementations; the Full HPF language was recognised as being tricky to implement. Some of the Full HPF features have yet to be implemented by any of the vendors.

The subset was designed to cover most of the common and useful Fortran 90 features. MODULE s were not deemed that important by HPFF but most vendors implemented them very early in the development cycles as users find them very powerful. Examples of Fortran 90 features absent from subset HPF are derived types, parameterised types and pointers. All but the latter are implemented by most compilers now.

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We shall study the following HPF features:

• processor arrangements,
• static alignment,
• static distribution,
• FORALL statement,
• INDEPENDENT loops,
• PURE and EXTRINSIC procedures,

The Full HPF (v1) specification includes some features that are much harder to implement and less useful than other simpler features.

Here, we concentrate on the most useful HPF features and omits some of the more complex. Full HPF allows dynamic objects -- ie, objets that can be remapped part-way thorough execution of a program unit -- and inherited mappings (in a procedure). Both these features are very difficult to implement efficiently!

Many HPF features are now in Fortran 95.

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