Program-wide with RUSTFLAGS

Target features can be enabled program-wide by setting RUSTFLAGS. The following example enables avx and avx2, and disables fma:

RUSTFLAGS="-Ctarget-features=+avx,+avx2,-fma" cargo build

Instead of targeting specific features, a particular CPU can be targeted:

RUSTFLAGS="-Ctarget-cpu=skylake" cargo build

Rust can also target your specific CPU, with the special native CPU:

RUSTFLAGS="-Ctarget-cpu=native" cargo build

Warning

Enabling features program-wide can be dangerous!

If the program runs on a CPU that does not have an enabled feature, the program will crash.