llvm-bootstrap

Release-builder repository for prebuilt LLVM installs.

What this repository builds

Host platforms:

• Windows x64
• Linux x64
• macOS arm64

Enabled LLVM backends inside every host build:

• X86
• AArch64
• WebAssembly

Pinned LLVM version

The LLVM ref is stored in llvm.version.

Current default:

llvmorg-21.1.2

The workflow derives the release tag from that value:

• llvmorg-21.1.2 -> GitHub release tag llvm-21.1.2
• a raw commit SHA -> GitHub release tag llvm-<sha>

Build configuration

The builder is intentionally minimal and release-oriented:

• -DCMAKE_BUILD_TYPE=Release
• -DLLVM_ENABLE_ASSERTIONS=OFF
• -DLLVM_ABI_BREAKING_CHECKS=FORCE_OFF
• -DLLVM_INCLUDE_TESTS=OFF
• -DLLVM_INCLUDE_BENCHMARKS=OFF
• -DLLVM_INCLUDE_EXAMPLES=OFF
• -DLLVM_INCLUDE_DOCS=OFF
• -DLLVM_TARGETS_TO_BUILD=X86;AArch64;WebAssembly
• -DBUILD_SHARED_LIBS=OFF
• -DLLVM_BUILD_LLVM_DYLIB=OFF
• -DLLVM_BUILD_LLVM_C_DYLIB=OFF
• -DLLVM_LINK_LLVM_DYLIB=OFF
• -DLLVM_ENABLE_ZLIB=OFF
• -DLLVM_ENABLE_ZSTD=OFF
• -DLLVM_ENABLE_LIBXML2=OFF
• -DLLVM_ENABLE_TERMINFO=OFF
• macOS default deployment target: 11.0
• Windows default CRT mode: -DCMAKE_MSVC_RUNTIME_LIBRARY=MultiThreaded (/MT)

The optional external dependencies are disabled so the packaged binaries are less tied to whatever happens to be installed on the GitHub runner image.

The current defaults are chosen to produce a better general-purpose package for downstream consumers:

• Windows defaults to a static LLVM build with static MSVC runtime (/MT)
• Linux and macOS default to static LLVM builds
• every archive carries a build manifest so consumers can see exactly which toolchain produced it

Release assets

Each release publishes:

• llvm-<version>-windows-x64-static.zip
• llvm-<version>-linux-x64-static.tar.xz
• llvm-<version>-macos-arm64-static.tar.xz
• SHA256SUMS.txt

Each archive contains a standard LLVM install root:

• bin/
• include/
• lib/
• share/

The install is meant to stay compatible with LLVM_SYS_211_PREFIX.

Each archive also contains:

• share/llvm-bootstrap/BUILDINFO.json

That manifest records the package linkage/runtime mode and the build provenance used to produce it, including:

• LLVM ref and package version
• CMake and Ninja versions
• compiler/linker version details
• Windows toolset and SDK details when applicable
• macOS deployment target when applicable

The Windows archive is a better default package than the previous floating-runtime variant, but it is still not a guarantee of universal MSVC compatibility for all downstream static-link scenarios.

GitHub Actions flow

The main workflow lives at .github/workflows/build.yml.

You can run it in two modes:

1. workflow_dispatch with publish_release=true
2. Push a Git tag like llvm-21.1.2

The workflow:

1. Reads the pinned ref from llvm.version
2. Checks out llvm/llvm-project at that ref
3. Builds and installs LLVM on each supported host runner
4. Packages each install into its platform archive format
5. Uploads intermediate workflow artifacts
6. Generates SHA256SUMS.txt
7. Publishes or updates the matching GitHub release

The CI defaults are configured through workflow env vars:

• LLVM_LINKAGE=Static
• LLVM_WINDOWS_MSVC_RUNTIME=MT
• LLVM_MACOS_DEPLOYMENT_TARGET=11.0

Triggering builds

Local builds

build_local.ps1 and build_local.sh are now the reusable source-bootstrap entrypoints for this repo. They:

• clone llvm-project at the requested ref
• build and install LLVM to the requested directories
• optionally package the install

Examples:

Windows:

./build_local.ps1
./build_local.ps1 -InstallDir C:\tmp\llvm-install
./build_local.ps1 -Package

Unix:

./build_local.sh
./build_local.sh --install-dir /tmp/llvm-install
./build_local.sh --package

Manual trigger from GitHub Actions

Use this when you want to test or publish the current pinned LLVM version without pushing a release tag:

1. Push the repository to GitHub
2. Open the Actions tab
3. Select Build LLVM Releases
4. Click Run workflow
5. Leave publish_release=true to publish the archives to a GitHub release, or set it to false to only run the builds

Tag-driven release trigger

Use this when you want the build to be tied to a specific versioned release:

1. Update llvm.version
2. Commit and push that change
3. Push a matching git tag named llvm-<version>

Examples:

• llvm.version = llvmorg-21.1.2 -> push tag llvm-21.1.2
• llvm.version = 0123abcd -> push tag llvm-0123abcd

The workflow validates that the pushed tag matches the version derived from llvm.version. If they do not match, the release job fails on purpose.

Example commands:

git add llvm.version
git commit -m "Bump LLVM to 21.1.2"
git push origin main
git tag llvm-21.1.2
git push origin llvm-21.1.2