A necessary condition for the establishment, on a substantial basis, of a parallel software industry would appear to be the availability of technology for generating transportable software, i.e. architecture independent software which delivers scalable performance for a wide variety of applications on a wide range of multiprocessor computers. We are in the process of developing H-BSP — a general purpose parallel computing environment for developing transportable algorithms. H-BSP is based on the Bulk Synchronous Parallel Model (BSP), in which a computation involves a number of supersteps, each having several parallel computational threads that synchronize at the end of the superstep. The BSP Model deals explicitly with the notion of communication among computational threads and introduces parameters g and L that quantify the ratio of communication throughput to computation throughput, and the synchronization period, respectively. These two parameters, together with the number of processors and the problem size, are used to quantify the performance and, therefore, the transportability of given classes of algorithms across machines having different values for these parameters. Recently algorithm designers have developed algorithms for a number of regular problems that are provably optimal as functions of g and L, but for many irregular problems developing optimal solutions will depend on the compiler and the run-time system taking advantage of the g and L values for the intended target. This paper describes the unbundled compiler technology and, particularly, the optimization technology it provides, that facilitates the development of such a parallel computer environment.