Discussion of the HPF Extension Subset

• []Rationale. The data mapping features of the HPF subset are limited to static mappings, plus the possible remapping of arguments across the interface of subprogram boundaries. Since the subset language does not include MODULES, and COMMON block variables cannot be remapped, this restriction only impacts remapping of local variables and additional remapping of arguments, after the subprogram boundary.

  

  Only the simplest version of FORALL statement is required in the subset. Note that the omission of the PURE attribute from the subset means that only HPF and Fortran 90 intrinsic functions can be called from the FORALL statement. No other subprograms can be called.

  Only the intrinsics which are useful for declaration of variables and mapping inquiries are included in the subset. The full set of extended operations proposed for the HPF library is not required and since MODULE is not part of the subset, the HPF_LIBRARY module is also not part of the subset. The extrinsic interface attribute is also not in the subset. This includes any specific extrinsic models such as the model described in the Annex .

  All of these HPF language reductions are made in the spirit of allowing vendors to produce a usable subset version of HPF quickly so that initial experimentation with the language can begin. This list of HPF features excluded from the subset should not be interpreted as requiring implementors to omit the features from the subset. Implementations with as many HPF features as possible are encouraged. The list does, however, establish the features a user should avoid if an HPF application is expected to be moved between different HPF subset implementations. (End of rationale.)