Summary

In this chapter, we went into a lot of detail on how the JIT compiler works and discussed the tiered compilation patterns that JVM uses to optimize the code. We also walked through various optimization techniques with a number of sample code examples. This provided a good understanding of the internal workings of JVM.

JVMCI provides the extensibility to build custom JIT compilers on JVM. Graal JIT is an implementation of JVMCI.

This chapter provided the basis for understanding how JVM works, and how JIT compilation optimizes the code at runtime. This is key in understanding how the Graal JIT compiler works.

In the next chapter, we will understand how the Graal VM architecture is built on the JVM architecture, and how it extends it to support Polyglot.