Managed Runtime Systems: Lecture 07 - Meta-circular VMs

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1. Managed Runtime Systems Lecture 07: Meta-circular VMs Foivos Zakkak https://foivos.zakkak.net Except where otherwise noted, this presentation is licensed under the Creative Commons Attribution 4.0 International License. Third party marks and brands are the property of their respective holders.
2. Meta-circularity Using the language that the VM implements to write the VM itself! Managed Runtime Systems 1 of 9 https://foivos.zakkak.net
3. Why??? 1. All the advantages of managed and high-level languages 2. Consistent calling conventions (going from app to VM and back) 3. Consistent Types and sizes 4. Consistent memory model 5. Re-use the same compilers at compile-time and run-time 6. Maintainability Managed Runtime Systems 2 of 9 https://foivos.zakkak.net
4. But! 1. Slower product 2. Slower development cycles 3. Thinking in a meta-circular manner is not trivial (hard to find bugs) 4. More complex testing infrastructure Managed Runtime Systems 3 of 9 https://foivos.zakkak.net
5. Using a substrate VM Rely on C compilers to produce machine code C-based implementation of a minimal runtime Bootstraps the Java in Java VM and implements system handling JIT compilation with C compilers is too slow, LLVM aims to fix that Squawk VM is one such example Managed Runtime Systems 4 of 9 https://foivos.zakkak.net
6. Re-using the same compiler at compile-time and run-time Old VM javac MyCompiler.java MyCompiler.class MyCompiler.java MyVM.java Old VM My VM + Compiler HelloWorld.class Hello World!!! Managed Runtime Systems 5 of 9 https://foivos.zakkak.net
7. Re-using the same compiler at compile-time and run-time Old VM javac MyCompiler.java MyCompiler.class MyCompiler.java MyVM.java Old VM My VM + Compiler HelloWorld.class Hello World!!! Managed Runtime Systems 5 of 9 https://foivos.zakkak.net
8. Re-using the same compiler at compile-time and run-time Old VM javac MyCompiler.java MyCompiler.class MyCompiler.java MyVM.java Old VM My VM + Compiler HelloWorld.class Hello World!!! Managed Runtime Systems 5 of 9 https://foivos.zakkak.net
9. Re-using the same compiler at compile-time and run-time Old VM javac MyCompiler.java MyCompiler.class MyCompiler.java MyVM.java Old VM My VM + Compiler HelloWorld.class Hello World!!! Managed Runtime Systems 5 of 9 https://foivos.zakkak.net
10. Difficulties Needs access to unsafe parts of the language How to avoid GC being run during GC Managed Runtime Systems 6 of 9 https://foivos.zakkak.net
11. Examples of Java in Java VMs Jikes Research VM (aka JikesRVM) Maxine VM Managed Runtime Systems 7 of 9 https://foivos.zakkak.net
12. Jikes RVM Originally known as Jalapeño Adopted by the academia Features the Memory Management Toolkit (MMTk) Relies on a magic layer for its implementation on different platforms 2 JIT compilers, no interpreter No 64bit port Managed Runtime Systems 8 of 9 https://foivos.zakkak.net
13. Maxine VM Predecessor of the Graal Compiler, a JIT compiler for Java written in Java Modular design (GC, Compilers, Memory layout, Monitors, etc.) Template based compilation More next time! Managed Runtime Systems 9 of 9 https://foivos.zakkak.net