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YJIT: Dive into Ruby's JIT compiler written in ...
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Takashi Kokubun
September 23, 2022
Programming
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YJIT: Dive into Ruby's JIT compiler written in Rust / Rust.Tokyo 2022
Rust.Tokyo 2022
Takashi Kokubun
September 23, 2022
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Transcript
YJIT: Dive into Ruby's JIT compiler written in Rust @k0kubun
/ Rust.Tokyo 2022
Me • @k0kubun • Shopify ◦ YJIT team • Ruby
committer ◦ MJIT maintainer
What’s YJIT?
None
None
None
None
How does YJIT work?
How YJIT works Ruby code
How YJIT works 1 + 2 Parse Ruby code Abstract
Syntax Tree
How YJIT works 1 + 2 Parse Ruby code Abstract
Syntax Tree putobject 1 putobject 2 opt_plus leave Compile Bytecode
How YJIT works 1 + 2 Parse Ruby code Abstract
Syntax Tree putobject 1 putobject 2 opt_plus leave Compile JIT Bytecode Machine code
How YJIT works putobject 1 putobject 2 opt_plus leave JIT
? Machine code Bytecode
How YJIT works: Ruby 3.1 putobject 1 putobject 2 opt_plus
leave x86_64 Codegen Machine code Bytecode
How YJIT works: Ruby 3.2 putobject 1 putobject 2 opt_plus
leave Machine code Bytecode
How YJIT works: Ruby 3.2 putobject 1 putobject 2 opt_plus
leave Machine code Bytecode
Lazy Basic Block Versioning
Lazily compile basic blocks
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
Lazily compile basic blocks
getlocal a getlocal b opt_plus setlocal c getlocal c putobject
1 opt_gt branchunless Branch stub Branch stub Lazily compile basic blocks
getlocal a getlocal b opt_plus setlocal c getlocal c putobject
1 opt_gt branchunless getlocal a leave Branch stub Lazily compile basic blocks
getlocal a getlocal b opt_plus setlocal c getlocal c putobject
1 opt_gt branchunless getlocal a leave Branch stub Lazily compile basic blocks
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
Why lazy compilation? 1. Better code locality a. Only compile
used paths b. Related code is put together
Why lazy compilation? 1. Better code locality a. Only compile
used paths b. Related code is put together 2. More type information
Type Profiling
Type Profiling getlocal a getlocal b opt_plus
Type Profiling getlocal a getlocal b opt_plus
Type Profiling getlocal a getlocal b jmp regenerate
Type Profiling getlocal a getlocal b jmp regenerate
Type Profiling getlocal a getlocal b jmp regenerate a: 1
b: 2
Type Profiling getlocal a getlocal b opt_plus (int) setlocal c
getlocal c putobject 1 opt_gt branchunless
Passes • CodeGen -> Split -> Alloc Regs
Passes • CodeGen -> Split -> Alloc Regs
IR
IR Split
IR Split Alloc Regs
Rust Challenges
Clang and Bindgen Clang dependency or Per-architecture codegen?
Mutable Borrow
Next steps • Code GC • Register allocation • Method
inlining
Conclusion • We reviewed the architecture of YJIT • Rust
has been useful for transforming IR