CS 17-770: Virtual Machines and Managed Runtimes

Instructor: Ben L. Titzer
Syllabus: here
Piazza: https://piazza.com/class/m06ykpnmt331by
Class time: Tues & Thurs 9:30am - 10:50am
Teaching Assistant(s): Arjun Ramesh

Traditional compiler and programming language courses focus on language implementations that generate code statically (offline) for a target machine. Yet in today's landscape, many programming languages run on virtual machines where either a virtual instruction set architecture (bytecode) or the source code of the program is translated (and optimized) dynamically for an underlying machine. Such languages come with additional challenges beyond traditional compilation as taught in courses, including efficient representation of high-level language constructs and automatic memory management in the form of garbage collection. Together, the components of the virtual machine and services form what is known as a managed runtime system. This course focuses on implementation techniques for managed runtime systems. Students will learn the basics of virtual machine implementation and build working prototypes to run actual programs. Prior knowledge of compilers and some familiarity with programming language implementation is required.

Key topics

• code formats: bytecodes and source code
• loading and verifying code
• interpreters: execution of bytecode and/or IR
• runtime system: object, function, and class representations, inline caches
• memory management: allocators and automatic garbage collection
• dynamic compilers: baseline and optimizing JIT compilers
• comparative study of historical virtual machines

Recommended Reading

Lecture Notes

• Lecture 1 (Aug 27) - What is a Virtual Machine?
• Lecture 2 (Aug 29) - Code Formats
• Lecture 3 (Sep 3) - WebAssembly .wasm Binary Format
• Lectures 4 & 5 & 6 - (Sep 5 & 10 & 12) - WebAssembly Runtime Semantics
• Lecture 7 - (Sep 17 [recording] [code]) - Java class format
• Lecture 8 - (Sep 19 [recording] [bytecodes]) - Java Runtime Semantics
• Lectures 9 & 10 & 11 - (Sep 24 & 26 & Oct 1) Object models
• Lectures 12 & 13 - (Oct 3 & 8) Wasm-GC object model
• Lecture 14 - (Oct 10) Intro to JIT compilers
• In-class Midterm - (Oct 22) One page of personal handwritten notes allowed
• Guest Lecture - (Oct 24) Andrew Begel
• Lecture 15 & 16 (Oct 29 & 31) - Baseline JITs
• Lecture 17 & 18 & 19 (Nov 7 & 12 & 14) - Optimizing JITs
• Lectures 20 - 21 (Nov 19 & 21 & 28) - Garbage Collection (Nov 26 Lecture)
• Lectures 22 - 24 (TBD) - Threads, putting it all together

Assessment Structure

• 10 points - (due Sep 17, 9:00pm) Project 1
• 10 points - (due Oct 1, 9:00pm) Project 2
• 20 points - Midterm Exam (Oct 22 in-class)
• 0 points - (due Nov 6) Final Project Proposal
• 12 points - (due Nov 6, 9:00pm) Project 3A or Project 3B
• 13 points - (due Dec 13, 9:00pm) Final Project
• 25 points - Final Exam (Dec 9, 8:30 am, in-person)
• 10 points - (due Dec 16, 9:00pm) Engine report

Office Hours

• Ben Titzer: Tuesdays 1-2pm; Wednesdays 2-3pm; or by appointment
• Arjun Ramesh: Mondays 11am-12pm; Thursdays 12-1pm; or by appointment (Location: CIC 2313C)