Code for the JVM->LLVM JIT Compiler (Proof-of-Concept) is here: https://github.com/LouisJenkinsCS/LLVM-JVM
A 'toy' JVM interpreter written in Haskell. Currently, it is considered a 'toy' in that it is not the intention of the author for this to be used as a viable JVM compared to others such as Hotspot or Oracle's implementations. This is being developed purely for educational purposes, and as such, I may or may not diverge from the JVM specification.
Mind you that this is purely educational, and while I do admit that Haskell may NOT be the best language for an interpreter, I chose Haskell because I love challenges. Haskell is infamous for being difficult to learn, and so I figured it would be fun to do so.
There is no particular logical reasons for as to why I chose Haskell beyond this. However, I would say that Haskell would definitely be better for a JIT Compilation virtual machine instead of an interpreter, and as such I plan to make those overhauls in the future (given the time).
This project originally was for a computer science course, called the "Organization of Programming Languages", and so I figured, why not knock out two birds with one stone by not only teaching myself a new language, a new paradigm, and to learn more about how languages are implemented?
- Parse
.classfile into data structure representation - Implement support for minimal attributes, (I.E:
Codeattribute) - Implement support for all attributes
- Create a stack frame representation
- Create a heap with minimal garbage collection
- Implement bootstrap class loader for runtime
- Implement load and store operations
- Implement arithmetic operations
- Implement conditionals +
gotojumps - Implement all instructions
The Virtual Machine implements small stubs for certain method calls that simulate
the runtime, such as System.out.println, and as well as appending to a StringBuilder.