Data

Tools

Indexes

Applications

Experiments

Awesome

An open API service indexing awesome lists of open source software.

https://github.com/edf-hpc/verrou

floating-point errors checker
https://github.com/edf-hpc/verrou

arithmetic diagnostics floating-point valgrind

Last synced: 3 months ago
JSON representation

floating-point errors checker

Awesome Lists containing this project

README 

          
# Verrou

[![gitHubAction](https://github.com/edf-hpc/verrou/actions/workflows/github-actions-travis.yml/badge.svg)](https://github.com/edf-hpc/verrou/actions/workflows/github-actions-travis.yml)

[![Documentation](https://img.shields.io/badge/docs-latest-blue.svg)](http://edf-hpc.github.io/verrou/vr-manual.html)



Verrou helps you look for floating-point round-off errors in programs. It

implements various forms of arithmetic, including:



- all IEEE-754 standard rounding modes;



- three variants of stochastic floating-point arithmetic based on random rounding:

  all floating-point operations are perturbed by randomly switching rounding

  modes. These can be seen as an asynchronous variant of the CESTAC method, or a

  subset of Monte Carlo Arithmetic, performing only output randomization through

  random rounding;



- an emulation of single-precision rounding, in order to test the effect of

  reduced precision without any need to change the source code.



Verrou also comes with the `verrou_dd_*` tools, which simplify the Verrou-based

debugging process by implementing several variants of the Delta-Debugging

algorithm. This allows easily locating which parts of the analyzed source code

are likely to be responsible for Floating-Point-related instabilities.



The documentation of the latest stable release is available as a dedicated [chapter in the

Valgrind manual](http://edf-hpc.github.io/verrou/vr-manual.html). For master version,

documentation generation is required (see below).



Documentation and support can also be found in the [verrou_support repository](https://github.com/edf-hpc/verrou_support).



## Installation



### Get the sources



The preferred way to get Verrou sources is to download the latest *stable*

version: [v2.6.0](https://github.com/edf-hpc/verrou/releases/latest).

Older versions are available in the [releases](https://github.com/edf-hpc/verrou/releases)

page. After downloading one of the released versions, skip to the "Configure

and build" section below.



 



In order to build the *development* version of Verrou, it is necessary to first

download a specific Valgrind version, and patch it. Fetch valgrind's sources:



    git clone --branch=VALGRIND_3_25_0 --single-branch https://sourceware.org/git/valgrind.git valgrind-3.25.0+verrou-dev



Add verrou's sources to it:



    cd valgrind-3.25.0+verrou-dev

    git clone https://github.com/edf-hpc/verrou.git verrou



    cat verrou/valgrind.*diff | patch -p1



### Configure and build



First, install all required dependencies (the names of relevant Debian packages

are put in parentheses as examples):



- C & C++ compilers (`build-essential`),

- autoconf & automake (`automake`),

- Python 3 (`python3`),

- C standard library with debugging symbols (`libc6-dbg`),

- [Optional] Python post-treatment tools (`python3-numpy`, `python3-matplotlib`, `texlive-latex-extra`, `texlive-fonts-recommended`, `dvipng`, `cm-super`).



 



Configure valgrind:



    ./autogen.sh

    ./configure --enable-only64bit --prefix=PREFIX



 



Advanced users can use the following configure flags :

- `--enable-verrou-fma=yes|no (default yes)`. This option is useful if your system does not support fma intrinsics.

- `--enable-verrou-sqrt=yes|no (default yes)`. This option is useful if your system does not support sqrt intrinsics.

- `--enable-verrou-check-naninf=yes|no` (default yes). If NaN does not appear in the verified code set this option to 'no' can slightly speed up verrou.

- `--with-det-hash=hash_name` with hash_name in [dietzfelbinger,multiply_shift,double_tabulation,xxhash,mersenne_twister] to select the hash function used for [random|average]_[det|comdet] rounding mode. The default is xxhash. double_tabulation was the previous default(before introduction of xxhash). mersenne_twister is the reference but slow. dietzfelbinger and multiply_shift are faster but are not able to reproduce the reference results.

- `--with-verrou-denorm-hack=[none|float|double|all]` (default float). With denormal number the EFT are no more necessary exact. With the average* rounding modes this problem is always ignored, but the random* rounding, there are the following available options :  with  `none` the problem is ignored. With `float` a hack based on computation in double is applied on float operations ; With `double` an experimental hack is applied for double operations ; With `all` the float and double hacks are applied. float is selected by default.

- `--enable-verrou-xoshiro=[no|yes]` (default yes). If set to yes the tiny mersenne twister prng is replaced (for random, prandom and average) by the xo[ro]shiro prng.

- `--enable-verrou-quad=[yes|no]` (default yes). If set to no the backend mcaquad is disabled. This option is only useful to reduce the dependencies.



 



Build and install:



    make

    make install



### Load the environment



In order to actually use Verrou, you must load the correct environment. This can

be done using:



    source PREFIX/env.sh



### Test (optional)



#### General tests



You can test the whole platform:



    make check

    perl tests/vg_regtest --all

    

or only verrou:



    make -C tests check

    make -C verrou check

    perl tests/vg_regtest verrou

    

    

#### Specific tests



These tests are more closely related to the arithmetic part in Verrou:



    make -C verrou/unitTest



## Documentation



The documentation for verrou is available as a

[chapter in valgrind's manual](//edf-hpc.github.io/verrou/vr-manual.html).



 



You can also re-build it:



    make -C docs html-docs man-pages



and browse it locally:



    firefox docs/html/vr-manual.html



Beware, this requires lots of tools which are not necessarily tested for in

`configure`, including (but not necessarily limited to):



  - xsltproc

  - docbook-xsl



## Bibliography & References



The following papers explain in more details the internals of Verrou, as well as

some of its applications. If you use Verrou for a research work, please consider

citing one of these references:



1. François Févotte and Bruno Lathuilière. Debugging and optimization of HPC

   programs with the Verrou tool. In *International Workshop on Software

   Correctness for HPC Applications (Correctness)*, Denver, CO, USA,

   Nov. 2019. [DOI: 10.1109/Correctness49594.2019.00006](http://dx.doi.org/10.1109/Correctness49594.2019.00006)

1. Hadrien Grasland, François Févotte, Bruno Lathuilière, and David

   Chamont. Floating-point profiling of ACTS using Verrou. *EPJ Web Conf.*, 214, 2019.

   [DOI: 10.1051/epjconf/201921405025](http://dx.doi.org/10.1051/epjconf/201921405025)

1. François Févotte and Bruno Lathuilière. Studying the numerical quality of an

   industrial computing code: A case study on code_aster. In *10th International

   Workshop on Numerical Software Verification (NSV)*, pages 61--80, Heidelberg,

   Germany,

   July 2017. [DOI: 10.1007/978-3-319-63501-9_5](http://dx.doi.org/10.1007/978-3-319-63501-9_5)

1. François Févotte and Bruno Lathuilière. VERROU: a CESTAC evaluation without

   recompilation. In *International Symposium on Scientific Computing, Computer

   Arithmetics and Verified Numerics (SCAN)*, Uppsala, Sweden, September 2016.



(These references are also available in [bibtex format](verrou.bib))