Own and improve Falcon, Azul’s LLVM-based JIT compiler, by designing, implementing, and validating optimizations across its middle and back ends. Responsibilities include code generation for x86_64 and AArch64, customer performance investigations, compiler performance analysis, code review, mentoring, and delivering measurable improvements to production workloads.
As the only company focused 100% on Java, Azul is building the Java platform for the modern cloud enterprise. We are reimagining how customers use Java, bringing them the tools and insight they need to deliver faster, more performant, more dependable, and less expensive Java services. Come join one of the most influential members of the Java and OpenJDK community and help influence the future of Java.
Falcon is the optimizing just in time (JIT) compiler in Azul Platform Prime. It compiles hot Java bytecode into highly optimized machine code and delivers Java performance that standard JVMs do not reach. Falcon is built on LLVM.
We are looking for a Senior Compiler Performance Engineer to own major performance areas of Falcon. This is not a compiler front end role and not a compiler built from scratch: Falcon is mature and runs in production at large enterprises. Your job is to push its generated code further, deciding which optimizations matter, designing them and delivering measurable speedups on real workloads.
You will work in a distributed team of compiler experts, with direct influence on what Falcon optimizes next.
What You Will Do
- Own performance of Falcon for a set of workloads or an optimization area end to end: analysis, design, implementation, validation
- Design and implement new optimizations and improve existing ones in the middle end and back end: inlining heuristics, loop optimizations, vectorization, escape analysis, speculation and deoptimization, 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 turn findings into compiler improvements
- Review code, mentor engineers on the team and raise the bar for performance methodology
Minimum 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
What We Offer
- Opportunity to make a high impact at a growing, global company
- Work alongside top experts worldwide contributing to the Java ecosystem
- Referral Program — help us grow with great people
- Premium IT equipment — MacBook Pro or hardware of your choice
- 5 weeks of holidays + 5 sick days
- Flexible working hours
- Prague / Limassol / Belgrade city center offices OR hybrid/full-remote - UP TO YOU
- Competitive compensation
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