Sebastian Pop
Compiler Engineer at LLVM Foundation
Austin, Texas, United States
Summary
🤩
Rockstar🎓
Top SchoolSebastian Pop is a compiler engineer with 23 years of experience building and optimizing compilers and toolchains for a wide range of architectures, now at NVIDIA and long associated with the LLVM Foundation and Free Software Foundation. He has driven arm64 performance improvements across major projects at AWS and contributed deep backend expertise to GCC, LLVM, and architecture ports (AArch64, x86, Hexagon), with notable work on HotColdSplitting and patchable functions. His open-source contributions include infrastructure and cross-platform build automation for Google OSS-Fuzz and intrinsics translation work in SSE2NEON, demonstrating skill in both low-level code generation and build/release automation. Sebastian’s background spans academia (PhD from Mines Paris - PSL) and industry, blending research-grade compiler analyses with production optimization for multimedia, language runtimes, and system libraries. He often tackles subtle ABI/SSA correctness and floating-point strictness issues that break optimized builds, a niche that few engineers combine with practical release engineering experience. Based in Austin, he’s known for improving real-world performance across toolchains while keeping projects robust and portable.
23 years of coding experience
18 years of employment as a software developer
MSc Computer Science, MSc Computer Science at University of LiverpoolCollege Saint-Etienne StrasbourgPhD Computer Science, PhD Computer Science at Mines Paris - PSLMSc Computer Science, MSc Computer Science at Université Louis Pasteur (Strasbourg I)
English, French, Romanian
Github Skills (39)
c-language10
intrinsics10
float3210
architecture10
computer-architecture10
compiler-development10
testing10
llvm10
cpu-architecture10
bash10
c1110
gcc10
x8610
c1710
arch10
Programming languages (13)
Github contributions (5)
DLTcollab/sse2neon
Mar 2020 - Feb 2021
A translator from Intel SSE intrinsics to Arm/Aarch64 NEON implementation
Role in this project:
Back-end Developer
Back-end DeveloperContributions:1 review, 18 commits, 10 PRs in 11 months
Contributions summary:Sebastian primarily contributed to implementing and testing SSE intrinsics to Arm/Aarch64 NEON implementations. Their work involved writing tests and modifying existing code to support functions like `_mm_storeh_pi`, `_mm_loadh_pi`, `_mm_avg_epu8`, `_mm_avg_epu16`, `_mm_maddubs_epi16`, and `_mm_sll_epi16`. Additionally, the user made changes to enable the test suite to run on x86 architecture and addressed compiler-specific behavior with NaN tests. These contributions focused on expanding the functionality and improving the cross-platform compatibility of the SSE to NEON translation library.
armv8-asimdsse-intrinsicsintrinsicsneon-intrinsics
llvm/llvm-test-suite
Oct 2016 - Dec 2016
Role in this project:Back-end Developer
Back-end DeveloperContributions:6 commits in 1 month
Contributions summary:Sebastian primarily contributed to the `llvm/llvm-test-suite` repository by implementing checks for strict floating-point computations within the Polybench benchmarks. Their work involved modifying existing code to run tests with and without strict floating-point flags, comparing results, and adding the necessary logic for error checking. The user also addressed issues related to compiler flags like `-ffp-contract=on`, ensuring the tests' correct behavior under different compilation settings. Furthermore, they removed function attributes and fixed several tests in the build-bots for Mips.
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