SPLASH 2021
Sun 17 - Fri 22 October 2021 Chicago, Illinois, United States
Thu 21 Oct 2021 14:35 - 14:50 at Zurich C - Implementation of special Paradigms Chair(s): Frank Tip
Thu 21 Oct 2021 22:35 - 22:50 at Zurich C - Implementation of special Paradigms - mirror Chair(s): Steve Blackburn

This paper shows how to compile sparse array programming languages. A sparse array programming language is an array programming language that supports element-wise application, reduction, and broadcasting of arbitrary functions over dense and sparse arrays with any fill value. Such a language has great expressive power and can express sparse and dense linear and tensor algebra, functions over images, exclusion and inclusion filters, and even graph algorithms.

Our compiler strategy generalizes prior work in the literature on sparse tensor algebra compilation to support any function applied to sparse arrays, instead of only addition and multiplication. To achieve this, we generalize the notion of sparse iteration spaces beyond intersections and unions. These iteration spaces are automatically derived by considering how algebraic properties annotated onto functions interact with the fill values of the arrays. We then show how to compile these iteration spaces to efficient code.

When compared with two widely-used Python sparse array packages, our evaluation shows that we generate built-in sparse array library features with a performance of 1.4$\times$ to 53.7$\times$ when measured against PyData/Sparse for user-defined functions and between 0.98$\times$ and 5.53$\times$ when measured against SciPy/Sparse for sparse array slicing. Our technique outperforms PyData/Sparse by 6.58$\times$ to 70.3$\times$, and (where applicable) performs between 0.96$\times$ and 28.9$\times$ that of a dense NumPy implementation, on end-to-end sparse array applications. We also implement graph linear algebra kernels in our system with a performance of between 0.56$\times$ and 3.50$\times$ compared to that of the hand-optimized SuiteSparse:GraphBLAS library.