cb48ea406e
This PR switches the default backend on x86, for both the `cranelift-codegen` crate and for Wasmtime, to the new (`MachInst`-style, `VCode`-based) backend that has been under development and testing for some time now. The old backend is still available by default in builds with the `old-x86-backend` feature, or by requesting `BackendVariant::Legacy` from the appropriate APIs. As part of that switch, it adds some more runtime-configurable plumbing to the testing infrastructure so that tests can be run using the appropriate backend. `clif-util test` is now capable of parsing a backend selector option from filetests and instantiating the correct backend. CI has been updated so that the old x86 backend continues to run its tests, just as we used to run the new x64 backend separately. At some point, we will remove the old x86 backend entirely, once we are satisfied that the new backend has not caused any unforeseen issues and we do not need to revert.
Fuzzing Infrastructure for Wasmtime
This crate provides test case generators and oracles for use with fuzzing.
These generators and oracles are generally independent of the fuzzing engine
that might be using them and driving the whole fuzzing process (e.g. libFuzzer
or AFL). As such, this crate does not contain any actual fuzz targets
itself. Those are generally just a couple lines of glue code that plug raw input
from (for example) libFuzzer into a generator, and then run one or more
oracles on the generated test case.
If you're looking for the actual fuzz target definitions we currently have, they
live in wasmtime/fuzz/fuzz_targets/* and are driven by cargo fuzz and
libFuzzer.