SFU-Sim reverse-engineers NVIDIA MUFU instructions into bit-exact models, open-sourced
ssh4net · x · 2026-11-13
Haozhi Xie and Tao Su released SFU-Sim (paper + MIT-licensed code): black-box reverse engineering of NVIDIA multi-function unit (MUFU) instructions to build bit-exact models, since vendor docs only specify semantics and error bounds, not exact output bit patterns.
- Covers 12 common MUFU forms plus two BF16 forms unique to the tested Blackwell (sm120) GPU, modeling full PTX-to-SASS paths including surrounding ops like FMUL.RZ prescale for SIN/COS.
- Complete SIN/COS case study: segment detection via even/odd pairing errors yields 64 segments with a 6+17-bit field split, per-segment fixed-point quadratic coefficients, and a truncated partial-product square feeding a Q37 fixed-point sum, normalized to FP32.
- Includes full model checks and exhaustive bit-exact validation over specified input domains.
Valuable for engineers needing exact GPU numerical reproduction, deterministic simulation, or cross-hardware consistency.
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