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Prebuilt LLVM Libraries

This repository builds and publishes prebuilt LLVM libraries used by rustc_codegen_nvvm. Building LLVM from source is slow and finicky — especially older versions — so we publish pinned, reproducible tarballs to GitHub releases that rustc_codegen_nvvm's build.rs can download.

The repo itself contains only the build scripts and CI; the tarballs live as release assets so cloning stays fast.

What's published

Each release is tagged llvm-<version> (e.g. llvm-19.1.7) and ships three assets:

Asset Target triple
linux-x86_64.tar.xz x86_64-unknown-linux-gnu
linux-aarch64.tar.xz aarch64-unknown-linux-gnu
windows-x86_64.tar.xz x86_64-pc-windows-msvc

Download URLs follow the standard GitHub releases pattern:

https://github.com/<owner>/<repo>/releases/download/llvm-<version>/<artifact>.tar.xz

CUDA dropped macOS support before any Rust-CUDA-relevant version, so no Darwin builds are produced.

Each tarball expands to a single top-level directory matching the target name (linux-x86_64/, linux-aarch64/, or windows-x86_64/) containing:

bin/
  llvm-config[.exe]   # probed by build.rs for components, cxxflags, libs
  llvm-as[.exe]       # used by the LLVM 19 build path to assemble libintrinsics.ll
include/
  llvm/
  llvm-c/
lib/
  *.{a,so,lib}        # static archives (and dylib on Linux)

bin/cmake and lib/pkgconfig are stripped because build.rs consumes the link-line via llvm-config, not find_package(LLVM).

Build configuration

Both LLVM 7 and LLVM 19 are built with the same flags:

  • CMAKE_BUILD_TYPE=Release
  • LLVM_TARGETS_TO_BUILD=X86;NVPTX (x86_64) or AArch64;NVPTX (aarch64)
  • LLVM_ENABLE_ASSERTIONS=OFF
  • LLVM_ENABLE_BINDINGS=OFF
  • LLVM_INCLUDE_{EXAMPLES,TESTS,BENCHMARKS}=OFF
  • Linux only: LLVM_BUILD_LLVM_DYLIB=ON, LLVM_LINK_LLVM_DYLIB=ON, LLVM_ENABLE_{ZLIB,TERMINFO}=ON

Linux builds run on ubuntu-22.04 (glibc 2.35) for both x86_64 and aarch64, giving a floor that matches the rust-cuda container baseline. Windows builds run on windows-2022. LLVM 7 on Windows is compiled with clang-cl from the preinstalled LLVM toolchain because MSVC v143 (the default compiler on windows-2022) refuses LLVM 7's older sources without source patches; LLVM 19 uses MSVC directly.

How to build and publish a new version

Trigger build-llvm.yml from the Actions tab via Run workflow, supplying the LLVM version (e.g. 7.1.0 or 19.1.7). The matrix runs on Linux (x86_64 and aarch64) and Windows runners. With the default release: true input, the workflow then creates (or updates) a release tagged llvm-<version> and uploads both tarballs as assets — re-running clobbers the existing assets, so it's safe to retry. Untick release to build without publishing; tarballs are still available as run artifacts on the workflow run page.

How to reproduce locally

The CI uses these scripts directly. To rebuild a tarball locally:

# Linux
LLVM_VERSION=19.1.7 INSTALL_PREFIX="$PWD/install" ./scripts/build-llvm-linux.sh
INSTALL_PREFIX="$PWD/install" ARTIFACT_NAME=linux-x86_64 ./scripts/package-prebuilt.sh

# Windows (PowerShell)
$env:LLVM_VERSION = '19.1.7'; $env:INSTALL_PREFIX = "$PWD\install"
./scripts/build-llvm-windows.ps1
$env:ARTIFACT_NAME = 'windows-x86_64'
bash ./scripts/package-prebuilt.sh