GeeVM

GeeVM is a JDK 17-compatible JVM implementation in C++, implemented as a learning project. It comes with full OpenJDK compatibility, JNI support and a copying garbage collector.

Building

Requirements

You'll require the following dependencies:

• C++23-compatible compiler,
• CMake 3.28 or newer,
• OpenJDK/OracleJDK 17,
• libzip.

GeeVM currently only supports on Linux.

Building with CMake

The CMake build requires OpenJDK/OracleJDK 17 to be present on the system in order to extract and copy the required classes from the JDK. By default, it will search in the directory specified by the environment variable JAVA_HOME.

After installing the dependencies and setting JAVA_HOME accordingly, you can build with the usual CMake commands:

cmake -B build -S . 
cmake --build build

Running the tests

Test files are full Java programs written either in Java or Jasmin and are found in the tests/programs directory.

Test execution is done using LLVM's lit and FileCheck tools that need to be installed separately. Once they are installed, you can run the full test suite using ctest:

cmake --build build --target test

Usage

Run the built java executable:

java <mainclass> [args]...

References

• JVM 17 Specification
• JNI 17 Specification