jvm

Toy JVM that might be useful. Uses GNU Classpath.

Progress

• [o] Implement all opcodes
  • Implement them correctly
• [o] Implement enough native methods to bootstrap the standard library
  • [.] Implement enough of the JNI too
• Execute a simple `System.out.println" call
• Integration test rig to compare output to a reference implementation
  • Fix all the bugs and unimplemented opcodes
• Fast, non-verifying interpreter optimised for speed

Usage

Not recommended in its current state

A nightly rust compiler is required for variadic functions in the JNI interface.

• Download, build and install GNU Classpath
  • I had luck with the following commands: CFLAGS="-w" ./configure --enable-load-library=yes --with-glibj=flat --enable-jni=yes --disable-gjdoc && make && make install
  • I also had to install antlr 3.5.2, gconf 2.6.0 and downgrade to a JDK that still has javah (OpenJDK 8)
• Find/compile a simple .java file into a .class
• cargo run -- <class name> --Xbootclasspath <colon separated list of paths to system classes> --cp <colon separated list of paths for non-system classes>
  • Example: cargo run -- com.me.MyClass --Xbootclasspath /gnuclasspath:../java --cp ../java. This will (try to) run the main method of ../java/com/me/MyClass.class
  • See help menu for more: cargo run -- --help