Automatic array alignment for distributed memory multicomputers

Languages such as Fortran-D and High Performance Fortran use explicit virtual processor arrays (Templates or Decompositions) to which the programmer aligns the arrays of the program. We explore a technique to automate this process. In particular, we are interested in imperative languages, similar to Fortran, and scientific computations using indexed data structures (arrays). We have implemented automatic alignment for our imperative language using techniques similar to those used for the functional language Crystal. Here we show what changes we made to the procedure to take into account the imperative nature of our source language. In particular, a functional language has a single-assignment attribute; each data element is defined only once. An imperative language allows array elements to be redefined; this allows the imperative program to use arrays with fewer dimensions, as we show. Our compiler technique "resurrects" the lost dimensions of the data arrays to successfully apply automatic data alignment.<>