2986f6b0ff
* ABI: implement register arguments with constraints. Currently, Cranelift's ABI code emits a sequence of moves from physical registers into vregs at the top of the function body, one for every register-carried argument. For a number of reasons, we want to move to operand constraints instead, and remove the use of explicitly-named "pinned vregs"; this allows for better regalloc in theory, as it removes the need to "reverse-engineer" the sequence of moves. This PR alters the ABI code so that it generates a single "args" pseudo-instruction as the first instruction in the function body. This pseudo-inst defs all register arguments, and constrains them to the appropriate registers at the def-point. Subsequently the regalloc can move them wherever it needs to. Some care was taken not to have this pseudo-inst show up in post-regalloc disassemblies, but the change did cause a general regalloc "shift" in many tests, so the precise-output updates are a bit noisy. Sorry about that! A subsequent PR will handle the other half of the ABI code, namely, the callsite case, with a similar preg-to-constraint conversion. * Update based on review feedback. * Review feedback.
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.