Tutorial Material

• SC24, Nov, 2024
• LANL, January, 2020
• SC19, Denver, Colorado, USA, Nov 17th, 2019
• PEARC19, Chicago, Illinois, USA, Jul 30th, 2019

Background

Dealing with floating-point arithmetic to perform numerical computations is challenging. Not only do round-off errors occur and accumulate at all levels of computation, but also compiler optimizations and low precision arithmetic can significantly affect the final computational results. With accelerators dominating HPC systems, computational scientists are faced with even bigger challenges to program reliable and reproducible floating-point programs.
This tutorial demonstrates tools that are available today to analyze floating-point scientific software.

Presentations

• 02/04/2020: Improving Reliability Through Analyzing and Debugging Floating-Point Software, Ignacio Laguna, 2020 ECP Annual Meeting, Houston, TX.
• 01/07/2020: Tools and Techniques for Floating-Point Analysis, Ignacio Laguna, LLNL.

Tools

FPChecker

FPChecker is tool to detect floating-point exceptions (e.g., NaNs, division by zero) on NVIDIA GPUs. It uses clang/LLVM to compile and instrument CUDA kernels. The tool informs to users the location where exceptions occurred (file and line number).

https://github.com/LLNL/FPChecker

FLiT

FLiT (Floating-point Litmus Tests) is a C++ test infrastructure for detecting variability in floating-point code caused by variations in compiler code generation, hardware and execution environments.

https://github.com/PRUNERS/FLiT

ADAPT

ADAPT is a tool for mixed precision analysis. The tool uses algorithmic differentiation to estimate the output error due to lowering the precision of variables. ADAPT also provides a floating-point rounding error sensitivity profile of the code.

https://github.com/LLNL/adapt-fp

Precimonious

Precimonious is a framework to automatically tune the precision of floating-point variables. The tool allows users to specify a target error and performance threshold, and uses the clang/LLVM compiler a main compiler infrastructure.

https://github.com/corvette-berkeley/precimonious

HiFPTuner

HiFPTuner is a dynamic precision tuner. Different from other tuners, it explores the community structure of the floating-point variables and uses the community structure to guide precision tuning to find better precision configurations in less time.

https://github.com/ucd-plse/HiFPTuner

FloatSmith

FloatSmith provides automated source-to-source tuning and transformation of floating-point code for mixed precision using three existing tools: 1) CRAFT, 2) ADAPT, and 3) TypeForge. The primary search loop is guided by CRAFT and uses TypeForge to prototype mixed-precision versions of an application. ADAPT results can optionally be used to help narrow the search space, and there are a variety of options to customize the search.

https://github.com/crafthpc/floatsmith

FPBench

FPBench provides benchmarks, compilers, and standards for the floating-point research community.

https://github.com/FPBench/FPBench

ReMPI

ReMPI is a record-and-replay tool for MPI+OpenMP applications. It helps in debugging floating-point program executions that produce different floating-point results due to MPI non-determinism.

https://github.com/PRUNERS/ReMPI

ARCHER

Archer is a data race detector for OpenMP programs. Archer combines static and dynamic techniques to identify data races in large OpenMP applications, leading to low runtime and memory overheads, while still offering high accuracy and precision.

https://github.com/PRUNERS/archer