Runtime interprocedural data placement optimisation for lazy parallel libraries (extended abstract

Abstract. We are developing a lazy, self-optimising parallel library of vector-matrix routines. The aim is to allow users to parallelise certain computationally expensive parts of numerical programs by simply link-ing with a parallel rather than sequential library of subroutines. The li-brary performs interprocedural data placement optimisation at runtime, which requires the optimiser itself to be very ecient. We achieve this rstly by working from aggregate loop nests which have been optimised in isolation, and secondly by using a carefully constructed mathemati-cal formulation for data distributions and the distribution requirements of library operators, which allows us largely to replace searching with calculation in our algorithm.