e95ffe4413
* Fix StructReturn handling: properly mark the clobber, and offset actual rets. The legalization of `StructReturn` was causing issues in the new call-handling code: the `StructReturn` ret was included in the `SigData` as if it were an actual CLIF-level return value, but it is not. Prior to using regalloc constraints for return values, we unconditionally included rax (or the architecture's usual return register) as a def, so it would be properly handled as "clobbered" by the regalloc. With the new scheme, we include defs on the call only for CLIF-level outputs. Callees with `StructReturn` args were thus not known to clobber the return-value register, and values might be corrupted. This PR updates the code to include a `StructReturn` ret as a clobber rather than a returned value in the relevant spots. I observed it causing saves/restores of rax in some CLIF that @bjorn3 provided me, but I was having difficulty minimizing this into a test-case that I would be comfortable including as a precise-output case (including the whole thing verbatim would lock down a bunch of other irrelevant details and cause test-update noise later). If we can find a more minimized example I'm happy to include it as a filetest. Fixes #5018.
filetests
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.
Adding a runtest
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.