Florian Hahn
Compiler Engineer at Apple
Leeds, England, United Kingdom
Summary
🤩
Rockstar🎓
Top SchoolFlorian Hahn is a compiler engineer with 15 years of experience building and optimizing toolchains for industry-leading platforms, currently advancing compiler technology at Apple after previous compiler roles at ARM. He brings deep low-level expertise in LLVM/Clang, AArch64 instruction encoding/decoding, and performance benchmarking, with contributions to high-profile projects like llvm, clang, and Rust's cargo. Florian pairs systems-level engineering with practical tooling improvements—ranging from micro-benchmarks for vectorization to adding CLI features and documentation—reflecting both algorithmic depth and developer ergonomics. A former teaching assistant at ETH Zurich and TU Wien, he blends research-minded rigor with production impact and has a knack for surfacing subtle correctness and performance fixes in complex backends.
16 years of coding experience
5 years of employment as a software developer
Vienna University of TechnologyMaster of Science (MSc), Computer Science, Master of Science (MSc), Computer Science at Eidgenössische Technische Hochschule Zürich
German, English
Github Skills (52)
unit-testing10
debugging10
benchmark10
assembly10
c-language10
cargo10
restructuredtext10
python10
sphinx10
tox10
llvm10
django10
testing10
databases10
benchmarking10
Programming languages (15)
Github contributions (5)
llvm/llvm-project
Sep 2021 - 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:3651 reviews, 40 commits, 841 PRs in 1 year 4 months
Contributions summary:Florian's commits primarily focus on compiler-related development within the LLVM project. The contributions involve fixing bugs, enhancing code generation, and contributing to testing infrastructure. This is evidenced by the user's work on tasks such as resolving aliasing issues, improving cost modeling, and updating test cases, reflecting a strong understanding of compiler internals and optimization techniques.
compilerllvmtoolchain
llvm/llvm-test-suite
Apr 2018 - Sep 2022
Role in this project:Performance Engineer
Performance EngineerContributions:46 reviews, 24 commits, 8 PRs in 4 years 5 months
Contributions summary:Florian's contributions primarily involve performance benchmarking and optimization within the LLVM test suite. They added a micro-benchmark for loop interchange optimization and created benchmarks for loop vectorization using libm math functions. Additionally, they introduced SLP vectorization benchmarks focused on memory versioning cases. These contributions are aimed at improving the performance of LLVM's compilation process.
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