Towards Ruby 4 JIT / RubyKaigi 2022

RubyKaigi 2022

Transcript

1. Towards Ruby 4 JIT
   @k0kubun
   

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2. @k0kubun
   Maintain: MJIT, Haml, ERB
   Shopify team
   

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3. GitHub Sponsors
   

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4. Haml 6
   

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5. Introduction to Ruby JIT
   

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6. How does Ruby JIT work?
   Ruby
   

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7. How does Ruby JIT work?
   1
   +
   2
   Ruby
   Abstract
   

   Syntax
   

   Tree
   

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8. How does Ruby JIT work?
   1
   +
   2
   putobject 1
   
   
   putobject 2
   
   
   opt_plus
   
   
   leave
   Ruby
   Abstract
   

   Syntax
   

   Tree
   Instruction
   

   Sequence
   

   (Bytecode)
   

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9. How does Ruby JIT work?
   1
   +
   2
   putobject 1
   
   
   putobject 2
   
   
   opt_plus
   
   
   leave
   Ruby
   Abstract
   

   Syntax
   

   Tree
   Instruction
   

   Sequence
   

   (Bytecode)
   Machine
   

   Code
   

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10. How does Ruby JIT work?
    

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11. CRuby JIT 1: MJIT
    

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12. CRuby JIT 2: YJIT
    

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13. Current CRuby JITs
    speed.yjit.org
    

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14. Current CRuby JITs
    speed.yjit.org
    

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15. Current CRuby JITs
    • YJIT
    
    
    • Available since Ruby 3.1
    
    
    • --jit or --yjit
    
    
    • MJIT
    
    
    • Available since Ruby 2.6
    
    
    • --mjit
    

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16. Current CRuby JITs
    • YJIT
    
    
    • Ruby 3.1: x86_64 only, no code GC, written in C
    
    
    • Ruby 3.2: arm64 support, (hopefully) code GC, written in Rust
    
    
    • MJIT
    
    
    • Ruby 3.1: Stable-ish, portable, native threads, written in C
    
    
    • Ruby 3.2: Experimental, fork + SIGCHLD, written in Ruby
    

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17. MJIT in Ruby
    

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20. mjit.rb: Secret "standard library" in Ruby 3.2
    • mjit.rb
    
    
    • Even more powerful than TracePoint
    
    
    • You can monkey-patch CRuby JIT
    
    
    • No compatibility guarantee
    
    
    • Every module is private, so const_get is required
    

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21. BYOJ: Bring Your Own JIT
    

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22. BYOJ: Bring Your Own JIT
    • Load and pause MJIT with --mjit=pause
    
    
    • Define RubyVM::MJIT.compile
    
    
    • Use RubyVM::MJIT.const_get(:C) to hack RubyVM
    
    
    • Call RubyVM::MJIT.resume to start JIT
    With Ruby 3.2:
    

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23. YJIT-style JIT
    • Monkey-patch RubyVM::MJIT.compile
    

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24. MJIT-style JIT
    • Monkey-patch RubyVM::MJIT::Compiler.compile
    

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25. MJIT-style JIT
    

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26. Everyone is writing CRuby JIT
    

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27. Benchmarking Ruby JIT
    

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28. yjit-bench
    

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29. yjit-bench
    • yjit-bench has three kinds of benchmarks:
    
    
    1. Headlining Benchmarks
    
    
    2. Other Benchmarks
    
    
    3. Micro Benchmarks
    

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30. 1. Headlining benchmarks
    • activerecord
    
    
    • hexapdf
    
    
    • liquid-render
    
    
    • mail
    
    
    • psych-load
    
    
    • railsbench
    ✉
    

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31. 2. Other Benchmarks
    • binarytrees, fankuchredux, nbody
    
    
    • chunky_png
    
    
    • erubi, erubi_rails
    
    
    • lee
    
    
    • optcarrot
    
    
    • rubykon
    

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32. 3. Micro Benchmarks
    • 30k_ifelse, 30k_methods
    
    
    • cfunc_itself, str_concat
    
    
    • fib
    
    
    • getivar, setivar
    
    
    • keyword_args
    
    
    • respond_to
    

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34. Benchmark Your Own JIT
    • ./run_benchmarks.rb -e “/path/to/ruby --any-option”
    
    
    • Pass multiple -e options to compare different JITs
    

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35. Towards Ruby 4 JIT
    

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36. My wish on Ruby 4 JIT
    • I want Ruby 4 to be as fast as Java or JavaScript
    
    
    • Ruby 4's performance should be a reason to leave Python
    

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38. More Concrete Examples
    

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42. Ruby 4 Canary
    • true is mov-ed (immediate)
    
    
    • No opt_* VM instruction
    
    
    • Constant folding
    
    
    • Ruby / C method inlining
    

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43. Ruby 4 Canary’
    • Single branch instruction
    to access @one
    
    
    • Single register to access
    two
    
    
    • No heap allocation
    
    
    • No stack frame
    

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46. Ruby 4 Canary 2
    • 5000050000 is mov-ed
    (immediate)
    
    
    • Ruby -> C -> Ruby inlining
    

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47. How can we get there?
    

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48. Optimization Challenges
    1. Constants
    
    
    2. Variables
    
    
    3. Method calls
    
    
    4. Garbage collection
    

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49. 1. Constants
    

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50. 1. Constants
    

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51. 1. Constants
    

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52. 1. Constants
    

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53. 1. Constants
    

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54. 1. Constants
    

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55. 1. Constants
    

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56. 1. Constants
    

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57. 2. Variables
    

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58. 2. Variables
    

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59. 2. Variables
    

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60. 2. Variables
    

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61. 2. Variables
    

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62. 2. Variables
    

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63. 2. Variables
    

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64. 2. Variables
    

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65. 2. Variables
    

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66. 2. Variables
    

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67. 2. Variables
    

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68. 2. Variables
    2021 2022 (tomorrow)
    

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69. 3. Method calls
    

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70. 3. Method calls
    

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71. 3. Method calls
    

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72. 3. Method calls
    

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73. 3. Method calls
    

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74. 3. Method calls
    

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75. 3. Method calls
    • Code locality
    
    
    • Method inlining: C 㱻 Ruby
    
    
    • Pass arguments with native ABI
    
    
    • Deoptimization on redefinition or interruption (or TracePoint)
    

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76. 4. Garbage collection
    

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77. 4. Garbage collection
    

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78. 4. Garbage collection
    

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79. Next Steps
    • We still have a lot of rooms for improvements on yjit-bench
    
    
    • More cross-instruction optimizations
    
    
    • More method inlining over Ruby and C
    

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80. Conclusion
    • Build your own JIT with Ruby 3.2
    
    
    • Benchmark your JIT with yjit-bench
    

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