OpenMP library linkage for Rust programs

This crate allows using OpenMP-dependent C code with Rust. It makes Cargo link to OpenMP, so that C static libraries linked with Rust programs can use OpenMP.

It can't be used with pure Rust programs (Rayon is a better choice for Rust).

NB: this crate can't automatically enable OpenMP for C code compiled from build scripts. You also need to pass -fopenmp//openmp flag to the C compiler (see usage below).

Requirements

• libgomp.* present in a directory printed by cc -print-search-dirs, vcomp.dll on Windows
• OpenMP-enabling flag set for any C code linked with the Rust program.

Usage

Linking

You can set static feature or set OPENMP_STATIC=1 env var to link OpenMP statically, so that executables using it are usable on machines without a compiler installed.

toml [dependencies.openmp] features = ["static"] version = "0.1"

Enabling

Cargo build scripts will get DEP_OPENMP_FLAG env var set which contains either -fopenmp or /openmp, depending on the target compiler. If you're building C code with cc-rs:

rust cc.flag(&env::var("DEP_OPENMP_FLAG").unwrap());

macOS

In macOS Clang pretends to be the gcc executable, but doesn't support OpenMP. Install brew install gcc from Homebrew and compile with CC=gcc-7 cargo build. You may need to run cargo clean first if it doesn't take effect.

Static linking is recommended on macOS.