ASPaS: A Framework for Automatic SIMDization of Parallel Sorting on x86-based Many-core Processors

Due to the difficulty that modern compilers have in vectorizing applications on vector-extension architectures, programmers resort to manually programming vector registers with intrinsics in order to achieve better performance. However, the continued growth in the width of registers and the evolving library of intrinsics make such manual optimizations tedious and error-prone. Hence, we propose a framework for the Automatic SIMDization of Parallel Sorting (ASPaS) on x86-based multicore and manycore processors. That is, ASPaS takes any sorting network and a given instruction set architecture (ISA) as inputs and automatically generates vectorized code for that sorting network. By formalizing the sort function as a sequence of comparators and the transpose and merge functions as sequences of vector-matrix multiplications, ASPaS can map these functions to operations from a selected "pattern pool" that is based on the characteristics of parallel sorting, and then generate the vectorized code with the real ISA intrinsics. The performance evaluation of our ASPaS framework on the Intel Xeon Phi coprocessor illustrates that automatically generated sorting codes from ASPaS can outperform the sorting implementations from STL, Boost, and Intel TBB.