Automatic annotation of tasks in structured code
Pedro Ramos, Gleison de Souza, Divino Soares, Guido Costa Souza De Araujo, Fernando Magno Quintão Pereira · 2018
This paper describes the design and implementation of a suit of static analyses and code generation techniques to annotate programs with OpenMP pragmas for task parallelism. These techniques approximate the ranges covered by memory regions, bound recursive tasks and estimate the profitability of tasks. We have used these ideas to implement a source-to-source compiler that inserts OpenMP pragmas into C/C++ programs without any human intervention. By building onto the static program analysis literature, and relying on OpenMP's runtime ability to disambiguate pointers, we show that we can annotate large and convoluted programs, often replicating the performance gains of handmade annotation. Furthermore, our techniques give us the means to discover opportunities of parallelism that remained buried in the syntax of well-known benchmarks for many years -sometimes leading to up to four-fold speedups on a 12-core machine at zero programming cost.