`funcref`s are implemented as `NonNull<VMCallerCheckedAnyfunc>`.
This should be more efficient than using a `VMExternRef` that points at a
`VMCallerCheckedAnyfunc` because it gets rid of an indirection, dynamic
allocation, and some reference counting.
Note that the null function reference is *NOT* a null pointer; it is a
`VMCallerCheckedAnyfunc` that has a null `func_ptr` member.
Part of #929
This is enough to get an `externref -> externref` identity function
passing.
However, `externref`s that are dropped by compiled Wasm code are (safely)
leaked. Follow up work will leverage cranelift's stack maps to resolve this
issue.
* Use `Linker` in `*.wast` testing
By default `Linker` disallows shadowing previously defined items, but it
looks like the `*.wast` test suites rely on this so this commit adds a
boolean flag to `Linker` as well indicating whether duplicates are
allowed.
* Review comments
* Add a test with a number of recursive instances
* Deny warnings in doctests
* No tabs
* Add a first-class way of accessing caller's exports
This commit is a continuation of #1237 and updates the API of `Func` to
allow defining host functions which have easy access to a caller's
memory in particular. The new APIs look like so:
* The `Func::wrap*` family of functions was condensed into one
`Func::wrap` function.
* The ABI layer of conversions in `WasmTy` were removed
* An optional `Caller<'_>` argument can be at the front of all
host-defined functions now.
The old way the wasi bindings looked up memory has been removed and is
now replaced with the `Caller` type. The `Caller` type has a
`get_export` method on it which allows looking up a caller's export by
name, allowing you to get access to the caller's memory easily, and even
during instantiation.
* Add a temporary note
* Move some docs
* Move `Func` to its own file
* Support `Func` imports with zero shims
This commit extends the `Func` type in the `wasmtime` crate with static
`wrap*` constructors. The goal of these constructors is to create a
`Func` type which has zero shims associated with it, creating as small
of a layer as possible between wasm code and calling imported Rust code.
This is achieved by creating an `extern "C"` shim function which matches
the ABI of what Cranelift will generate, and then the host function is
passed directly into an `InstanceHandle` to get called later. This also
enables enough inlining opportunities that LLVM will be able to see all
functions and inline everything to the point where your function is
called immediately from wasm, no questions asked.
* Document and update the API of the `externals.rs` module
This commit ensures that all public methods and items are documented in
the `externals.rs` module, notably all external values that can be
imported and exported in WebAssembly. Along the way this also tidies up
the API and fixes a few bugs:
* `Global::new` now returns a `Result` and fails if the provided value
does not match the type of the global.
* `Global::set` now returns a `Result` and fails if the global is either
immutable or the provided value doesn't match the type of the global.
* `Table::new` now fails if the provided initializer does not match the
element type.
* `Table::get` now returns `Option<Val>` instead of implicitly returning
null.
* `Table::set` now returns `Result<()>`, returning an error on out of
bounds or if the input type is of the wrong type.
* `Table::grow` now returns `Result<u32>`, returning the previous number
of table elements if succesful or an error if the maximum is reached
or the initializer value is of the wrong type. Additionally a bug was
fixed here where if the wrong initializer was provided the table would
be grown still, but initialization would fail.
* `Memory::data` was renamed to `Memory::data_unchecked_mut`.
Additionally `Memory::data_unchecked` was added. Lots of caveats were
written down about how using the method can go wrong.
* `Memory::grow` now returns `Result<u32>`, returning an error if growth
fails or the number of pages previous the growth if successful.
* Run rustfmt
* Fix another test
* Update crates/api/src/externals.rs
Co-Authored-By: Sergei Pepyakin <s.pepyakin@gmail.com>
Co-authored-by: Sergei Pepyakin <s.pepyakin@gmail.com>
* Remove `HostRef` from the `wasmtime` public API
This commit removes all remaining usages of `HostRef` in the public API
of the `wasmtime` crate. This involved a number of API decisions such
as:
* None of `Func`, `Global`, `Table`, or `Memory` are wrapped in `HostRef`
* All of `Func`, `Global`, `Table`, and `Memory` implement `Clone` now.
* Methods called `type` are renamed to `ty` to avoid typing `r#type`.
* Methods requiring mutability for external items now no longer require
mutability. The mutable reference here is sort of a lie anyway since
the internals are aliased by the underlying module anyway. This
affects:
* `Table::set`
* `Table::grow`
* `Memory::grow`
* `Instance::set_signal_handler`
* The `Val::FuncRef` type is now no longer automatically coerced to
`AnyRef`. This is technically a breaking change which is pretty bad,
but I'm hoping that we can live with this interim state while we sort
out the `AnyRef` story in general.
* The implementation of the C API was refactored and updated in a few
locations to account for these changes:
* Accessing the exports of an instance are now cached to ensure we
always hand out the same `HostRef` values.
* `wasm_*_t` for external values no longer have internal cache,
instead they all wrap `wasm_external_t` and have an unchecked
accessor for the underlying variant (since the type is proof that
it's there). This makes casting back and forth much more trivial.
This is all related to #708 and while there's still more work to be done
in terms of documentation, this is the major bulk of the rest of the
implementation work on #708 I believe.
* More API updates
* Run rustfmt
* Fix a doc test
* More test updates
* Remove the need for `HostRef<Store>`
This commit goes through the public API of the `wasmtime` crate and
removes the need for `HostRef<Store>`, as discussed in #708. This commit
is accompanied with a few changes:
* The `Store` type now also implements `Default`, creating a new
`Engine` with default settings and returning that.
* The `Store` type now implements `Clone`, and is documented as being a
"cheap clone" aka being reference counted. As before there is no
supported way to create a deep clone of a `Store`.
* All APIs take/return `&Store` or `Store` instead of `HostRef<Store>`,
and `HostRef<T>` is left as purely a detail of the C API.
* The `global_exports` function is tagged as `#[doc(hidden)]` for now
while we await its removal.
* The `Store` type is not yet `Send` nor `Sync` due to the usage of
`global_exports`, but it is intended to become so eventually.
* Touch up comments on some examples
* Run rustfmt
* Update the `*.wast` runner to use the `wasmtime` API
This commit migrates the `wasmtime-wast` crate, which executes `*.wast`
test suites, to use the `wasmtime` crate exclusively instead of the raw
support provided by the `wasmtime-*` family of crates.
The primary motivation for this change is to use `*.wast` test to test
the support for interface types, but interface types is only being added
in the `wasmtime` crate for now rather than all throughout the core
crates. This means that without this transition it's much more difficult
to write tests for wasm interface types!
A secondary motivation for this is that it's testing the support we
provide to users through the `wasmtime` crate, since that's the
expectation of what most users would use rather than the raw
`wasmtime-*` crates.
* Run rustfmt
* Fix the multi example
* Handle v128 values in the `wasmtime` crate
Ensure that we allocate 128-bit stack slots instead of 64-bit stack
slots.
* Update to master
* Add comment
* Migrate back to `std::` stylistically
This commit moves away from idioms such as `alloc::` and `core::` as
imports of standard data structures and types. Instead it migrates all
crates to uniformly use `std::` for importing standard data structures
and types. This also removes the `std` and `core` features from all
crates to and removes any conditional checking for `feature = "std"`
All of this support was previously added in #407 in an effort to make
wasmtime/cranelift "`no_std` compatible". Unfortunately though this
change comes at a cost:
* The usage of `alloc` and `core` isn't idiomatic. Especially trying to
dual between types like `HashMap` from `std` as well as from
`hashbrown` causes imports to be surprising in some cases.
* Unfortunately there was no CI check that crates were `no_std`, so none
of them actually were. Many crates still imported from `std` or
depended on crates that used `std`.
It's important to note, however, that **this does not mean that wasmtime
will not run in embedded environments**. The style of the code today and
idioms aren't ready in Rust to support this degree of multiplexing and
makes it somewhat difficult to keep up with the style of `wasmtime`.
Instead it's intended that embedded runtime support will be added as
necessary. Currently only `std` is necessary to build `wasmtime`, and
platforms that natively need to execute `wasmtime` will need to use a
Rust target that supports `std`. Note though that not all of `std` needs
to be supported, but instead much of it could be configured off to
return errors, and `wasmtime` would be configured to gracefully handle
errors.
The goal of this PR is to move `wasmtime` back to idiomatic usage of
features/`std`/imports/etc and help development in the short-term.
Long-term when platform concerns arise (if any) they can be addressed by
moving back to `no_std` crates (but fixing the issues mentioned above)
or ensuring that the target in Rust has `std` available.
* Start filling out platform support doc
