# AliveToolkit/alive2

Automatic verification of LLVM optimizations

Repository: https://github.com/AliveToolkit/alive2
Canonical: https://ross.abutalabs.com/products/alive2
Language: C++
License: MIT
License Family: permissive
Topics: llvm, verification, translation-validation, automatic-verification, smt, llvm-ir, symbolic-execution, model-checking
Last push: 2026-08-31T14:03:31+00:00

## Health v2 (maintenance only)
Score: 71/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 100, release rhythm 18, longevity 100
- inputs: {"age_days": 3007, "days_push": 2, "days_rel": 386, "gap_med": 101.5, "n_releases_24m": 3}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1162, forks 159 (observed 2026-09-01T02:13:54.051702+00:00)

## What it is
Alive2 is a set of C++ libraries and tools for automatically verifying LLVM code and optimization transformations using symbolic execution and SMT solving. It provides translation validation plugins for clang and LLVM's opt, a standalone verifier (alive-tv), and a UB-precise LLVM IR interpreter.

## Use cases
- verify that an LLVM optimization pass preserves semantics
- check compiler transformations for miscompilation bugs
- run translation validation while compiling C/C++ with clang
- interpret LLVM IR with precise undefined behavior detection
- fuzz-test LLVM passes for correctness
- validate IR refinements with an SMT solver

## When to choose
- you are developing or testing LLVM optimization passes and need automatic correctness checking
- you want to catch miscompilations in compiler transformations before they ship
- you need a UB-precise interpreter for LLVM IR

## When to avoid
- you need inter-procedural transformation verification, which Alive2 does not support
- you work with languages or IRs other than LLVM IR
- you need a lightweight tool without building LLVM and Z3 from source

## Facets
- artifact type: library
- maturity: active
- function: testing, compiler, interpreter, developer-tools
- domain: compilers, developer-tools, programming-languages
- platform: windows, cpp, cli
- tags: llvm, translation-validation, smt, z3, symbolic-execution, formal-verification, llvm-ir, optimization-verifier, algorithms, linux, macos

## Member repositories
- AliveToolkit/alive2 (main) score 71

## Provenance
- Observed fields: from GitHub, fetched 2026-09-01T02:13:54.051702+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 2026-08-30T06:31:50.888032+00:00, confidence not recorded.
  - readme: https://github.com/AliveToolkit/alive2 (fetched 2026-09-01T02:13:54.051702+00:00, sha f76a35f0c785)
- Data as of 2026-08-30T08:39:29.467469+00:00.