During October 2025, Kexu implemented a C2 JIT compiler optimization in the openjdk/leyden repository, focusing on improving arithmetic-heavy Java code. The work introduced pattern matching and transformation logic in the AddNode, enabling the compiler to collapse repeated additions of the same value into a single multiplication, and further optimize multiplications into bit shifts when possible. This required extending the intermediate representation and developing comprehensive tests to ensure correctness and performance gains. Utilizing C++ and Java, Kexu demonstrated strong skills in code generation, compiler optimization, and JIT compilation, delivering a well-tested feature that reduces instruction count and enhances runtime efficiency.