Debugging and Optimization of HPC Programs with the Verrou Tool

The analysis of Floating-Point-related issues in HPC codes is becoming a topic of major interest: parallel computing and code optimization often break the reproducibility of numerical results across machines, compilers and even executions of the same program. This paper presents how the Verrou tool can help during all stages of the Floating-Point analysis of HPC codes: diagnose, debugging and optimization. Recent developments of Verrou are presented, along with examples illustrating the interest of these new features for industrial codes such as code aster. More specifically, the Verrou arithmetic back-ends now allow analyzing or emulating mixed-precision programs. Interlibm, an interposition layer for the mathematical library, is introduced to mitigate long-standing issues with algorithms from the libm. Finally, debugging algorithms are extended in order to produce useful information as soon as it is available. All these features are available in released version 2.1.0 and upcoming version 2.2.0.