This commit updates the various tooling used by wasmtime which has new
updates to the module linking proposal. This is done primarily to sync
with WebAssembly/module-linking#26. The main change implemented here is
that wasmtime now supports creating instances from a set of values, nott
just from instantiating a module. Additionally subtyping handling of
modules with respect to imports is now properly handled by desugaring
two-level imports to imports of instances.
A number of small refactorings are included here as well, but most of
them are in accordance with the changes to `wasmparser` and the updated
binary format for module linking.
Recent changes to fuzzers made expectations more strict about handling
errors while fuzzing, but this erroneously changed a module compilation
step to always assume that the input wasm is valid. Instead a flag is
now passed through indicating whether the wasm blob is known valid or
invalid, and only if compilation fails and it's known valid do we panic.
This commit removes the binaryen support for fuzzing from wasmtime,
instead switching over to `wasm-smith`. In general it's great to have
what fuzzing we can, but our binaryen support suffers from a few issues:
* The Rust crate, binaryen-sys, seems largely unmaintained at this
point. While we could likely take ownership and/or send PRs to update
the crate it seems like the maintenance is largely on us at this point.
* Currently the binaryen-sys crate doesn't support fuzzing anything
beyond MVP wasm, but we're interested at least in features like bulk
memory and reference types. Additionally we'll also be interested in
features like module-linking. New features would require either
implementation work in binaryen or the binaryen-sys crate to support.
* We have 4-5 fuzz-bugs right now related to timeouts simply in
generating a module for wasmtime to fuzz. One investigation along
these lines in the past revealed a bug in binaryen itself, and in any
case these bugs would otherwise need to get investigated, reported,
and possibly fixed ourselves in upstream binaryen.
Overall I'm not sure at this point if maintaining binaryen fuzzing is
worth it with the advent of `wasm-smith` which has similar goals for
wasm module generation, but is much more readily maintainable on our
end.
Additonally in this commit I've added a fuzzer for wasm-smith's
`SwarmConfig`-based fuzzer which should expand the coverage of tested
modules.
Closes#2163
