Some language issues in high performance computing: translation from fine-grained parallelism to coarse-grained parallelism.

A parallel programming model, BEC, was proposed in [1], to enable Global Address Space (GAS) capabilities for programming in SPMD style . It is a portable light-weight approach for incremental acceptance of the GAS model, along an evolution path that leverages existing infrastructures . It assists migration of legacy applications thereby encouraging their expert programmers to adopt the new model . BEC also provides for some unaddressed needs, such as ef f icient support for high-volume fine-grained random communications . BEC can be used as an enhancement to existing environments such as MPI. This report presents a scheme for a compiler to translate high level GAS languages PRAM C ([2]) and UPC ([9]) into BEC . Since PRAM C implements the theoretical Parallel Random Access Machine (PRAM) model [5] and BEC implements the Bulk Synchronous Parallel (BSP) model [10], such a translation by a compiler is theoretically significant, because it is the first time that a program in PRAM semantics (fined-grained parallelism) is translated into program in BSP style (coarse-grained parallelism) . This provides a bridge from the PRAM model (considered impractical) to the BSP model (considered practical) . Because BEC leverages infrastructures on existing platforms (such as * email : spgoudy@sandia .gov temail : zwen@sandia .gov