Worked on the pytorch/FBGEMM repository to address a bug related to AVX512_256 instruction set handling. Focused on improving the initialization logic by introducing std::optional from the C++ Standard Library, enabling explicit state management for the AVX512_256 flag. Developed an environment variable override mechanism using FBGEMM_ENABLE_AVX512_256, ensuring predictable and configurable behavior across different environments, with a safe default to false when unset. The work required careful low-level optimization and robust environment variable handling in C++. This targeted fix enhanced the reliability and flexibility of instruction set usage without introducing new features during the development period.