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Azul is seeking a Senior Compiler Performance Engineer to own major performance areas of Falcon, the optimizing JIT compiler in Azul Platform Prime. Falcon compiles hot Java bytecode into highly optimized machine code and is built on LLVM. This is a mature, production-grade compiler running at large enterprises—not a greenfield build or frontend role.
You will push Falcon's generated code quality further by deciding which optimizations matter most, designing them, and delivering measurable speedups on real workloads. You'll work in a distributed team of compiler experts with direct influence on Falcon's optimization roadmap.
Key Responsibilities:
- Own performance of Falcon for a set of workloads or optimization area end-to-end: analysis, design, implementation, and validation
- Design and implement new optimizations and improve existing ones in the middle end and back end, including inlining heuristics, loop optimizations, vectorization, escape analysis, speculation and deoptimization, and GC barrier and runtime call optimization
- Drive code generation quality on x86_64 and AArch64, including bringing Falcon to new hardware platforms
- Investigate complex performance issues reported by customers and translate findings into compiler improvements
- Review code, mentor engineers on the team, and raise the bar for performance methodology
- Contribute to upstream LLVM where appropriate
Requirements:
- 5+ years of professional experience developing optimizing compilers or JIT compilers
- Strong C++ design and coding skills in large codebases
- Proven track record of delivering compiler optimizations with measurable performance impact
- Deep knowledge of compiler optimization theory and its practical tradeoffs (compile time, code size, correctness)
- Strong performance analysis skills: profilers, hardware counters, reading and reasoning about generated assembly
Nice to Have:
- Significant experience with LLVM optimization passes or code generation; LLVM commit access is a plus
- Experience with JIT compilers for managed languages (HotSpot C2, Graal, V8, .NET RyuJIT, or similar)
- Deep knowledge of x86_64 and/or AArch64 microarchitecture
- Experience with JVM internals: garbage collection, deoptimization, profiling
- PhD in Computer Science or significant research experience in compilers
