YJIT: Dive into Ruby's JIT compiler written in Rust / Rust.Tokyo 2022

Rust.Tokyo 2022

Transcript

1. YJIT: Dive into Ruby's JIT
   compiler written in Rust
   @k0kubun / Rust.Tokyo 2022
   

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2. Me
   ● @k0kubun
   ● Shopify
   ○ YJIT team
   ● Ruby committer
   ○ MJIT maintainer
   

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3. What’s YJIT?
   

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8. How does YJIT work?
   

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9. How YJIT works
   Ruby code
   

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10. How YJIT works
    1
    +
    2
    Parse
    Ruby code
    Abstract
    Syntax
    Tree
    

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11. How YJIT works
    1
    +
    2
    Parse
    Ruby code
    Abstract
    Syntax
    Tree
    putobject 1
    putobject 2
    opt_plus
    leave
    Compile
    Bytecode
    

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12. How YJIT works
    1
    +
    2
    Parse
    Ruby code
    Abstract
    Syntax
    Tree
    putobject 1
    putobject 2
    opt_plus
    leave
    Compile JIT
    Bytecode
    Machine code
    

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13. How YJIT works
    putobject 1
    putobject 2
    opt_plus
    leave
    JIT
    ?
    Machine code
    Bytecode
    

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14. How YJIT works: Ruby 3.1
    putobject 1
    putobject 2
    opt_plus
    leave
    x86_64
    Codegen
    Machine code
    Bytecode
    

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15. How YJIT works: Ruby 3.2
    putobject 1
    putobject 2
    opt_plus
    leave
    Machine code
    Bytecode
    

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16. How YJIT works: Ruby 3.2
    putobject 1
    putobject 2
    opt_plus
    leave
    Machine code
    Bytecode
    

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17. Lazy Basic Block Versioning
    

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18. Lazily compile basic blocks
    

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19. getlocal a
    getlocal b
    opt_plus
    setlocal c
    getlocal c
    putobject 1
    opt_gt
    branchunless
    getlocal a
    leave
    getlocal b
    leave
    Lazily compile basic blocks
    

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20. Lazily compile basic blocks
    

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21. getlocal a
    getlocal b
    opt_plus
    setlocal c
    getlocal c
    putobject 1
    opt_gt
    branchunless
    Branch stub Branch stub
    Lazily compile basic blocks
    

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22. getlocal a
    getlocal b
    opt_plus
    setlocal c
    getlocal c
    putobject 1
    opt_gt
    branchunless
    getlocal a
    leave
    Branch stub
    Lazily compile basic blocks
    

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23. getlocal a
    getlocal b
    opt_plus
    setlocal c
    getlocal c
    putobject 1
    opt_gt
    branchunless
    getlocal a
    leave
    Branch stub
    Lazily compile basic blocks
    

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24. getlocal a
    getlocal b
    opt_plus
    setlocal c
    getlocal c
    putobject 1
    opt_gt
    branchunless
    getlocal a
    leave
    getlocal b
    leave
    Lazily compile basic blocks
    

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25. Why lazy compilation?
    1. Better code locality
    a. Only compile used paths
    b. Related code is put together
    

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26. Why lazy compilation?
    1. Better code locality
    a. Only compile used paths
    b. Related code is put together
    2. More type information
    

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27. Type Profiling
    

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28. Type Profiling
    getlocal a
    getlocal b
    opt_plus
    

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29. Type Profiling
    getlocal a
    getlocal b
    opt_plus
    

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30. Type Profiling
    getlocal a
    getlocal b
    jmp regenerate
    

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31. Type Profiling
    getlocal a
    getlocal b
    jmp regenerate
    

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32. Type Profiling
    getlocal a
    getlocal b
    jmp regenerate
    a: 1
    b: 2
    

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33. Type Profiling
    getlocal a
    getlocal b
    opt_plus (int)
    setlocal c
    getlocal c
    putobject 1
    opt_gt
    branchunless
    

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34. Passes
    ● CodeGen -> Split -> Alloc Regs
    

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35. Passes
    ● CodeGen -> Split -> Alloc Regs
    

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36. IR
    

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37. IR
    Split
    

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38. IR
    Split
    Alloc Regs
    

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39. Rust Challenges
    

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40. Clang and Bindgen
    Clang dependency or
    Per-architecture codegen?
    

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41. Mutable Borrow
    

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42. Next steps
    ● Code GC
    ● Register allocation
    ● Method inlining
    

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43. Conclusion
    ● We reviewed the architecture of YJIT
    ● Rust has been useful for transforming IR
    

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