Filetests is a crate that contains multiple test suites for testing various parts of cranelift. Each folder under cranelift/filetests/filetests is a different test suite that tests different parts.

One of the available testsuites is the "runtest" testsuite. Its goal is to compile some piece of clif code, run it and ensure that what comes out is what we expect.

To build a run test you can add the following to a file:

test interpret
test run
target x86_64
target aarch64
target s390x

function %band_f32(f32, f32) -> f32 {
block0(v0: f32, v1: f32):
    v2 = band v0, v1
    return v2
}
; run: %band_f32(0x0.5, 0x1.0) == 0x1.5

Since this is a run test for band we can put it in: runtests/band.clif. Once we have the file in the test suite we can run it by invoking: cargo run -- test filetests/filetests/runtests/band.clif from the cranelift directory.

The first lines tell clif-util what kind of tests we want to run on this file. test interpret invokes the interpreter and checks if the conditions in the ; run comments pass. test run does the same, but compiles the file and runs it as a native binary.

For more information about testing see testing.md.