SchokoVM

A java bytecode interpreter that was implemented by two students for the course on Abstract Machines at the TU Wien.

The name was inspired by cacao jvm.

Slides of our presentation: presentation.pdf

Working:

• Load class and jar files.
• All instructions except invokedynamic.
• Objects/arrays.
• Exceptions.
• Native method calls.

Partially:

• OpenJDK 11 Class Library (System.out.println works).
• Some functions are still missing to use libjvm with java -XXaltjvm=.
• Primitive garbage collection.

Not implemented:

• Invokedynamic (String concatenation).
• Multi-threading / synchronized.
• Custom class loaders.
• Bytecode verification.

Build and test

The repository contains run configurations for the CLion IDE.

Command line instructions:

mkdir build
cd build
cmake ..
make -j
ctest -j 12

Ctest uses the script compare.sh to compare SchokoVM to the system JDK.

Dependencies

• Linux or macOS

• OpenJDK 11:

  If CMake finds the wrong version, you can set the JAVA_HOME environment variable.

• libzip, libdl, libffi

OpenJDK 11 sources

You can optionally download the source code for OpenJDK 11 with this script: cd jdk && ./download.sh. This is not necessary to compile the project.

Notes

Some bullet points about the jvm specification can be found in JvmSpecNotes.md.