A transformation method to reduce loop overhead in HPF compiler

Among data parallel languages, which were suggested to solve programming problems of distributed memory machines, HPF is regarded as standard data parallel language. Most HPF compilers are source-to-source translators because they can be implemented easily. Also, they currently generate significant amount of ineffective codes. In particular, the FORALL construct is converted into several DO loops, so loop overhead, which exacerbates program performance of these codes is substantially increased. Therefore HPF source-to-source compilers require some techniques to produce an optimized DO loop from the FORALL construct. The authors propose a transformation method to reduce loop overhead for the FORALL construct. For this, they define and use a relation distance vector which can represent both data dependence information and flow information. Then they evaluate and analyze the execution time for the codes converted by their method and by the PARADIGM method in aspects of array size and dependence distance.