The Indigo Program-Verification Microbenchmark Suite of Irregular Parallel Code Patterns

Abstract

Irregular programs are found in many domains and tend to exhibit input-dependent control flow and memory accesses. This paper introduces the Indigo suite of important irregular parallel code patterns for testing verification and other tools. We studied many irregular CPU and GPU programs and extracted the key code patterns. Then, we methodically built variations of these patterns to alter the control-flow and memory-access behavior and/or introduce bugs, yielding the thousands of OpenMP and CUDA microbenchmarks in the suite. Indigo includes a set of generators to systematically create an unbounded number of inputs for each microbenchmark, which is essential to exercise the wide range of possible behaviors of input-dependent codes. To manage the millions of code and input combinations, Indigo provides the flexibility to generate user-defined subsets of the suite. Experiments with a subset of buggy and bug-free codes illustrate that irregular programs pose a significant challenge to both static and dynamic program verification tools. Moreover, such tools can perform quite differently across code patterns that contain the same bug.