2025-10-13
A Tutorial
If you can ctrl-c and ctrl-v, you can build a JIT.
Copy-and-Patch
Tutorial
2025-10-13
How It Works
Clang optimizations. Machine code models. Relocations!
Calculator
Building a complete calculator rather than toy example involves solving a few more traditional compiler problems.
Ifs, loops, and more.
Efficient complex expressions and function bodies.
Turning compiled stencils into a library of code emitting and patching functions.
Building a library of stencils and efficiently selecting variants during code generation.
More posts will trickle out over time:
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Control Flow
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Register Allocation
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Stencil Library Generation
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Stencil Selection
Appendix
A closer look at WasmNow vs V8 Liftoff.
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Exceptions
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Debug info
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Profiling with JITDUMP
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Benchmarking with WasmNow
See discussion of this page on Reddit, Hacker News, and Lobsters.