Ruby YARV Challenge: Build Your Own Bytecode VM in 7 Steps

RubyKaigi 2026 Lightning Talks

Transcript

1. Ruby YARV Challenge: Build Your Own Bytecode VM in 7 Steps yuhi(@yuhi_junior) RubyKaigi 2026 Lightning Talks 2026-04-22 #rubykaigiA
2. 2 SmartBank, Inc. Software Engineer yuhi @yuhi_junior @Yuhi-Sato Self Introduction
3. Get Your Board43! @ HackSpace
4. • A browser-based workshop • Build simplified YARV bytecode and compiler in Ruby • Tutorials + hints at every step What’s “Ruby YARV Challenge”?
6. Motivation • The problem ◦ Stack machines and bytecode are unfamiliar concepts. ◦ YARV is written in C — hard to read for many Rubyists. • The solution ◦ Tutorials + hints guide you from zero — no prior VM knowledge needed. ◦ Reimplement YARV-like bytecode and compiler in Ruby — no C required
7. Where you implement the code bytecode (ISeq) AST Ruby code VM Exec parser compiler
8. Where you implement the code Prism Ruby API bytecode (ISeq) AST Ruby code VM Exec parser compiler
9. Where you implement the code yruby bytecode (ISeq) AST Ruby code VM Exec parser compiler
10. Where you implement the code Workshop code bytecode (ISeq) AST Ruby code VM Exec parser compiler
11. Goal Define and execute recursive Fibonacci on VM
12. 7 steps to reach the goal 1. Literal values (putobject) 2. Addition (opt_plus) 3. Subtraction (opt_minus) 4. Local variables (getlocal, setlocal, dup) 5. Comparison (opt_lt) 6. Control flow (branchunless, jump) 7. Method definition and dispatch (definemethod, opt_send_without_block)
13. 7 steps to reach the goal 1. Literal values (putobject) 2. Addition (opt_plus) 3. Subtraction (opt_minus) 4. Local variables (getlocal, setlocal, dup) 5. Comparison (opt_lt) 6. Control flow (branchunless, jump) 7. Method definition and dispatch (definemethod, opt_send_without_block)
14. Step 2: Addition • bytecode ◦ opt_plus • compile ◦ IntegerNode (Step 1) ◦ ArgumentsNode ◦ CallNode name: +
15. opt_plus opt_plus 1. pop two values 2. push the sum 1 2
16. opt_plus opt_plus 1. pop two values 2. push the sum 1 2
17. opt_plus opt_plus 1. pop two values 2. push the sum 1 2
18. opt_plus opt_plus 1. pop two values 2. push the sum 3
19. Compiler CallNode name: + IntegerNode value: 1 ArgumentsNode arguments: [2] receiver arguments putobject 1 putobject 2 opt_plus AST bytecode
20. Demo: Step 2 URL: https://yuhi-sato.github.io/ruby-yarv-challenge
21. Let’s try! URL: https://yuhi-sato.github.io/ruby-yarv-challenge
23. Workshop UI
24. Workshop UI: Tutorial left pane
25. Workshop UI: Code center pane
26. Workshop UI: Results right pane
27. Step 2: Addition CallNode name: + IntegerNode value: 1 ArgumentsNode arguments: [2] receiver arguments putobject 1 putobject 2 opt_plus AST bytecode
28. Step 2: Addition CallNode name: + IntegerNode value: 1 ArgumentsNode arguments: [2] receiver arguments putobject 1 putobject 2 opt_plus AST bytecode
29. Step 2: Addition • bytecode ◦ opt_plus • compile ◦ IntegerNode (Step 1) ◦ ArgumentsNode ◦ CallNode name: +
30. Step 2: Addition CallNode name: + IntegerNode value: 1 ArgumentsNode arguments: [2] receiver arguments putobject 1 putobject 2 opt_plus AST bytecode
31. Step 2: Addition • bytecode ◦ opt_plus • compile ◦ IntegerNode (Step 1) ◦ ArgumentsNode ◦ CallNode name: +
32. Step 2: Addition CallNode name: + IntegerNode value: 1 ArgumentsNode arguments: [2] receiver arguments • compile_integer_node （Step 1） • compile_arguments_node • compile_binary_plus putobject 1 putobject 2 opt_plus
33. Step 2: Addition CallNode name: + IntegerNode value: 1 ArgumentsNode arguments: [2] receiver arguments • compile_integer_node （Step 1） • compile_arguments_node • compile_binary_plus
34. Step 2: Addition • compile_integer_node （Step 1） • compile_arguments_node • compile_binary_plus CallNode name: + IntegerNode value: 1 ArgumentsNode arguments: [2] receiver arguments
35. Step 2: Addition • compile_integer_node （Step 1） • compile_arguments_node • compile_binary_plus CallNode name: + IntegerNode value: 1 ArgumentsNode arguments: [2] receiver arguments
36. Inspirations