Compiler Performance Engineer

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  Compiler Performance Engineer  to make Falcon generate even faster code. This is not a compiler front end role and not a compiler built from scratch: the compiler exists, runs in production at large enterprises, and your job is to find where the generated code is slower than it should be and fix it in the optimizer and code generator.
You will join a distributed team of compiler experts and work on real workloads with direct, measurable impact on customer performance.

What You Will Do   Analyze performance of Java benchmarks and customer workloads, find gaps in generated code and trace them to their root cause in the compiler
Implement and improve optimizations in Falcon's middle end and back end: inlining, loop optimizations, vectorization, redundancy elimination, speculative optimizations and their interaction with the runtime
Improve code generation for  and AArch
64
Write tests and benchmarks that prove the improvement and protect it from regressions
Contribute changes upstream to LLVM where it makes sense

Minimum Requirements   2+ years of professional experience in compilers, JIT compilers or low level performance engineering
Strong C++ design and coding skills
Solid understanding of compiler optimization theory: SSA, data flow analysis, loop transformations
Ability to read assembly and reason about why one instruction sequence is faster than another
Nice to Have   

Experience with LLVM IR and LLVM optimization passes, or with another optimizing compiler such as Hot Spot C2, Graal, GCC or V8

Experience with profilers such as perf, VTune or async profiler
Knowledge of  and/or AArch
64 microarchitecture

Experience with Java, Scala or Kotlin, or with JVM internals
MSc or PhD in Computer Science with a compiler or performance focus

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 — Mac Book Pro or hardware of your choice
Competitive paid holidays and sick time
Flexible working hours
Remote first OR Prague / Limassol / Belgrade city center offices OR hybrid - UP TO YOU!
Competitive compensation
We may use artificial intelligence (AI) tools to support parts of the hiring process, such as reviewing applications, analyzing resumes, or assessing responses and identifying potential inconsistencies or verification signals in application materials based on available information. These tools assist our recruitment team but do not replace human judgment. Final hiring decisions are ultimately made by humans. If you would like more information about how your data is processed, please contact us.