Givy is a runtime developed as part of the PhD thesis of François Gindraud. It is designed for architectures with distributed memories, with the Kalray MPPA as the main target. It will execute dynamic data-flow task graphs, annotated with memory dependencies. It will automatically handle scheduling and placement of tasks (using the memory dependency hints), and generate memory transfers between distributed memory nodes when needed by using a software cache coherence protocol. Most of the work this year was done on implementing and testing a memory allocator with specific properties that is a building block of the whole runtime. This memory allocator is also tuned to work on the MPPA and its constraints, turning with very little memory and being efficient in the context of multithreaded calls.
Tirex is a Textual Intermediate Representation for EXchanging target-level information between compiler optimizers and whole or parts of code generators (aka compiler back-end). The first motivation for this intermediate representation is to factor target-specific compiler optimizations into a single component, in case several compilers need to be maintained for a particular target (e.g., operating system compiler and application code compiler). Another motivation is to reduce the run-time cost of JIT compilation and of mixed mode execution, since the program to compile is already in a representation lowered to the level of the target processor.
The Tirex Intermediate Representation has previously been generated from within both the Open64 and GCC compilers. In order to increase the usability of Tirex and to decrease the amount of required code maintenance that is induced by compiler evolutions a Tirex-generator has been written that is capable of creating the Tirex representation of a program based on its corresponding assembler code.
BOAST is a metaprogramming framework to produce portable and efficient computing kernels for HPC application. BOAST offers an embedded domain specific language to describe the kernels and their possible optimization. BOAST also supplies a complete runtime to compile, run, benchmark, and check the validity of the generated kernels. BOAST is being used in two flagship HPC applications BigDFT and SPECFEM3D, to improve performance portability of those codes.
THEMIS consists of a library and command-line tools. It provides an API, data structures and measures for decentralized monitoring. These building blocks can be reused or extended to modify existing algorithms, design new more intricate algorithms, and elaborate new approaches to assess existing algorithms.
Interactive Debugging with a traditional debugger can be tedious. One has to manually run a program step by step and set breakpoints to track a bug. i-RV is an approach to bug fixing that aims to help developpers during their Interactive Debbugging sessions using Runtime Verification.
Verde is the reference implementation of i-RV.
Nanvix is an Operating System that we designed from scratch to address growing interested on research and education. It originally targets x86-based architectures and features virtual-memory based on paging, a hierarchical Unix file system based on inodes, a uniform device driver interface, and a preemptive priority-based scheduler.
We are currently extending Nanvix to provide a portable OS targetting multiple manycore platforms through the PhD of Pedro Henrique Penna.
Mickey is a set of tools for profiling based performance debugging for compiled binaries. It uses a dynamic binary translator to instrument arbitrary programs as they are being run to reconstruct the control flow and track data dependencies. This information is then fed to a polyhedral optimizer that proposes structured transformations for the original code. Mickey can handle both inter- and intra-procedural control & data flow in a unified way, thus enabling inter-procedural structured transformations. It is based on QEMU to allow for portability, both in terms of targeted CPU architectures, but also in terms of programming environment and the use of third-party libraries for which no source code is available.
Quantifier elimination is the process of removing existential variables of a given formula, obtaining one with less variables and that implies the original formula. This can also be viewed as a projection of the set of points (integer here) that satisfy the original formula onto a sub-vectorial space made up of all the non-eliminated variables. The obtained projection is an over-approximation of the exact projection. The goal of the process is to make it as tight as possible.
IPFME presents extensions to the Fourier-Motzkin quantifier elimination process. The developed techniques allow to derive more precise simplification operations when handling integer valued multivariate polynomial systems.
The implementation, in C++, uses GiNaC (https://www.ginac.de/) for the manipulation of symbolic expressions.
mcGDB defines the concept of “programming-model centric” source-level interactive debugging as an extension of the traditional language-level interactive debugging. The idea is to integrate into debuggers the notion of “programming models”, as abstract machines running over the physical ones. These abstract machines, implemented by runtime libraries and programming frameworks, provide high-level primitives required for the implementation of today’s parallel applications. mcGDB is developed as a Python extension of GDB, the debugger of the GNU project