libomp

Prebuilt static + shared libomp binaries from LLVM, for Bazel and general use.

Platforms

Platform	Triple	Variants	Format
Linux x86_64	x86_64-unknown-linux-gnu	static + shared	tar.gz
Linux arm64	aarch64-unknown-linux-gnu	static + shared	tar.gz
macOS x86_64	x86_64-apple-darwin	static + shared	tar.gz
macOS arm64	arm64-apple-darwin	static + shared	tar.gz
Windows x86_64	x86_64-pc-windows-msvc	shared only	zip
wasm32	wasm32-unknown-emscripten	static only	tar.gz

Bazel usage

# MODULE.bazel
bazel_dep(name = "libomp", version = "21.1.8")

# BUILD.bazel
cc_binary(
    name = "my_app",
    srcs = ["main.c"],
    copts = select({
        "@platforms//os:macos": ["-Xclang", "-fopenmp"],
        "@platforms//os:windows": ["/openmp:llvm"],
        "//conditions:default": ["-fopenmp"],
    }),
    deps = ["@libomp"],
)

-Xclang -fopenmp bypasses Apple Clang's driver (which rejects -fopenmp) and passes it directly to cc1, which has full OpenMP lowering support.

/openmp:llvm links our libomp. most windows users would prefer /openmp (msvc's vcomp) and skip the @libomp dep entirely.

To use a different LLVM version:

_libomp = use_extension("@libomp//:extensions.bzl", "libomp")
_libomp.version(version = "20.1.4")

Checksums are built-in starting LLVM 20.1.0.

See examples/ for test targets.

Build configuration

• CMAKE_INTERPROCEDURAL_OPTIMIZATION=OFF (-flto off)
• LIBOMP_OMPT_SUPPORT=ON (unix), OFF (windows -- upstream blocks it)
• LIBOMP_INSTALL_ALIASES=ON (unix -- libgomp/libiomp5 compat)
• OPENMP_ENABLE_LIBOMPTARGET=OFF (no GPU offloading)
• Linux builds use Alpine musl for static lib portability, manylinux2014/glibc 2.17 for shared lib
• Windows: shared-only (upstream cmake blocks static on Windows)
• wasm32: static-only, patched KMP_DEFAULT_BLOCKTIME for spin-wait (emscripten condvar latency workaround)