# nbp/holyjit

Generic purpose Just-In-time compiler for Rust.

Repository: https://github.com/nbp/holyjit
Canonical: https://ross.abutalabs.com/products/holyjit
Homepage: https://holyjit.org/
Language: Rust
License: MPL-2.0
License Family: copyleft
Last push: 2019-05-12T14:14:20+00:00

## Health v2 (maintenance only)
Score: 32/100 (v2, computed 2026-09-02T17:46:02.011165+00:00)
- activity 0, release rhythm 35, longevity 100
- inputs: {"age_days": 3247, "days_push": 2670, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: no_releases
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1554, forks 28 (observed 2026-08-28T04:05:02.970850+00:00)

## What it is
HolyJit is a generic-purpose Just-In-Time compiler library for Rust that extends the Rust compiler (as a rustc driver) to convert annotated interpreter code into JIT-compiled code. It lets developers write an ordinary Rust interpreter and annotate functions with a `jit!` macro to generate optimized JIT code without writing assembly.

## Use cases
- build a JIT compiler for my scripting language written in Rust
- speed up an interpreter without writing assembly
- annotate Rust functions to be inlined into JIT-compiled code
- avoid the security pitfalls of hand-written JIT compilers
- reduce startup time of a JIT with macro-guided early compilation tiers

## When to choose
- you are writing an interpreter in Rust and want JIT performance with minimal extra code
- you want a safe, high-level alternative to writing a MacroAssembler-based JIT
- you can adopt a rustc wrapper build workflow

## When to avoid
- you need a maintained, production-ready JIT (last release 2019, project appears inactive)
- your code is not written in Rust
- you need JIT for a language runtime not built as a Rust interpreter

## Facets
- artifact type: library
- maturity: abandoned
- function: compiler, interpreter, developer-tools
- domain: programming-languages, compilers, developer-tools, performance
- platform: rust, cross-platform
- tags: jit, rustc-driver, interpreter-optimization, macro-annotations, linux, macos

## Member repositories
- nbp/holyjit (main) score 32

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:05:02.970850+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T04:30:06.019903+00:00, confidence not recorded.
  - readme: https://github.com/nbp/holyjit (fetched 2026-08-28T04:05:02.970850+00:00, sha b0fd4cc9a67b)
- Data as of 2026-08-30T08:39:29.467469+00:00.