Guillaume Chatelet
Staff Software Engineer at Google
Paris, Ile-de-France
Summary
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Rockstar🎓
Top SchoolGuillaume Chatelet is a Staff Software Engineer based in Paris with 16 years of experience building and optimizing low-level systems and compilers. At Google since 2013, he focuses on backend and performance work, contributing to core projects like LLVM/Clang, LDC, and the D toolchain where he fixes bugs, tightens memory safety, and improves performance-critical routines such as memcpy prefetching. His background in image processing and AI from ENSICAEN and Université de Caen underpins a methodical, algorithm-first approach to engineering complex systems. An active open-source contributor, he has made notable changes to LLVM libc, D’s phobos, and cpu_features—work that requires deep understanding of architectures and ABI details. Colleagues rely on him for hard-to-debug compiler and portability issues, and he often surfaces subtle cross-language interoperability fixes that prevent runtime vulnerabilities.
16 years of coding experience
MSc, Image processing, Artificial Intelligence, Algorithmic, MSc, Image processing, Artificial Intelligence, Algorithmic at Université de Caen NormandieEngineer, Computer sciences, image processing, artificial intelligence, algorithmic, Engineer, Computer sciences, image processing, artificial intelligence, algorithmic at ENSICAEN - Ecole Nationale Supérieure d'Ingénieurs de Caen
Stackoverflow
213reputation
3kreached
2answers
2questions
Github Skills (41)
algorithm10
algorithms10
debug10
programming-language10
c-language10
llvm10
testing10
memory-management10
ranges10
c1110
dword10
data-structure10
feature-detection10
x8610
c1710
Programming languages (5)
Github contributions (5)
google/cpu_features
Dec 2017 - Jan 2023
A cross platform C99 library to get cpu features at runtime.
Role in this project:
Back-end Developer
Back-end DeveloperContributions:11 releases, 98 reviews, 189 commits in 5 years 1 month
Contributions summary:Guillaume primarily contributed to the core functionality of the `google/cpu_features` library. Their work involved adding and modifying code within the `src/cpuinfo_x86.c` file, which appears to be focused on retrieving and utilizing CPU features at runtime, specifically for x86 architectures. They were involved in fixing bugs related to features. They also converted the `list_cpu_features` program to C, improved compatibility, added caching of cpu info and updated the build process to support multiple architectures.
cpuwindowsbazelc99runtime
llvm/llvm-project
Oct 2022 - Jan 2023
The LLVM Project is a collection of modular and reusable compiler and toolchain technologies.
Role in this project:Back-end Developer
Back-end DeveloperContributions:239 reviews, 12 commits, 340 PRs in 3 months
Contributions summary:Guillaume primarily contributed to the LLVM libc project by fixing bugs, refactoring code, and improving the performance of the library. Their work involved modifying core components like `big_int.h`, `dyadic_float.h`, and related test files. They addressed issues related to bitwise operations, memory access, and build configurations. The user also made enhancements to the software prefetching mechanisms used by the memcpy functions, demonstrating a focus on optimization.
compilerstechnologiesclangsubmittoolchain
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