This commit fixes a panic related to type imports where an import of a
type didn't correctly declare the new type index on the Wasmtime side of
things. Additionally this plumbs more support throughout Wasmtime to
support type imports, namely that they do not need to be supplied
through a `Linker`. This additionally implements a feature where empty
instances, even transitively, do not need to be supplied by a Wasmtime
embedder. This means that instances which only have types, for example,
do not need to be supplied into a `Linker` since no runtime information
for them is required anyway.
Closes#5775
At some point what is now `funcref` was called `anyfunc` and the spec changed,
but we didn't update our internal names. This does that.
Co-authored-by: Jamey Sharp <jsharp@fastly.com>
This commit fixes more cases from #5565 where `export` items introducing
indices wasn't handled by accident. Additionally this fixes support for
aliasing types from instances which largely wasn't working before. Most
of the fixes here are about correctly maintaining Wasmtime's view of the
type index spaces.
* Update WIT tooling used by Wasmtime
This commit updates the WIT tooling, namely the wasm-tools family of
crates, with recent updates. Notably:
* bytecodealliance/wasm-tools#867
* bytecodealliance/wasm-tools#871
This updates index spaces in components and additionally bumps the
minimum required version of the component binary format to be consumed
by Wasmtime (because of the index space changes). Additionally WIT
tooling now fully supports `use`.
Note that WIT tooling doesn't, at this time, fully support packages and
depending on remotely defined WIT packages. Currently WIT still needs to
be vendored in the project. It's hoped that future work with `cargo
component` and possible integration here could make the story about
depending on remotely-defined WIT more ergonomic and streamlined.
* Fix `bindgen!` codegen tests
* Add a test for `use` paths an implement support
* Update to crates.io versions of wasm-tools
* Uncomment codegen tests
* Pull `Module` out of `ModuleTextBuilder`
This commit is the first in what will likely be a number towards
preparing for serializing a compiled component to bytes, a precompiled
artifact. To that end my rough plan is to merge all of the compiled
artifacts for a component into one large object file instead of having
lots of separate object files and lots of separate mmaps to manage. To
that end I plan on eventually using `ModuleTextBuilder` to build one
large text section for all core wasm modules and trampolines, meaning
that `ModuleTextBuilder` is no longer specific to one module. I've
extracted out functionality such as function name calculation as well as
relocation resolving (now a closure passed in) in preparation for this.
For now this just keeps tests passing, and the trajectory for this
should become more clear over the following commits.
* Remove component-specific object emission
This commit removes the `ComponentCompiler::emit_obj` function in favor
of `Compiler::emit_obj`, now renamed `append_code`. This involved
significantly refactoring code emission to take a flat list of functions
into `append_code` and the caller is responsible for weaving together
various "families" of functions and un-weaving them afterwards.
* Consolidate ELF parsing in `CodeMemory`
This commit moves the ELF file parsing and section iteration from
`CompiledModule` into `CodeMemory` so one location keeps track of
section ranges and such. This is in preparation for sharing much of this
code with components which needs all the same sections to get tracked
but won't be using `CompiledModule`. A small side benefit from this is
that the section parsing done in `CodeMemory` and `CompiledModule` is no
longer duplicated.
* Remove separately tracked traps in components
Previously components would generate an "always trapping" function
and the metadata around which pc was allowed to trap was handled
manually for components. With recent refactorings the Wasmtime-standard
trap section in object files is now being generated for components as
well which means that can be reused instead of custom-tracking this
metadata. This commit removes the manual tracking for the `always_trap`
functions and plumbs the necessary bits around to make components look
more like modules.
* Remove a now-unnecessary `Arc` in `Module`
Not expected to have any measurable impact on performance, but
complexity-wise this should make it a bit easier to understand the
internals since there's no longer any need to store this somewhere else
than its owner's location.
* Merge compilation artifacts of components
This commit is a large refactoring of the component compilation process
to produce a single artifact instead of multiple binary artifacts. The
core wasm compilation process is refactored as well to share as much
code as necessary with the component compilation process.
This method of representing a compiled component necessitated a few
medium-sized changes internally within Wasmtime:
* A new data structure was created, `CodeObject`, which represents
metadata about a single compiled artifact. This is then stored as an
`Arc` within a component and a module. For `Module` this is always
uniquely owned and represents a shuffling around of data from one
owner to another. For a `Component`, however, this is shared amongst
all loaded modules and the top-level component.
* The "module registry" which is used for symbolicating backtraces and
for trap information has been updated to account for a single region
of loaded code holding possibly multiple modules. This involved adding
a second-level `BTreeMap` for now. This will likely slow down
instantiation slightly but if it poses an issue in the future this
should be able to be represented with a more clever data structure.
This commit additionally solves a number of longstanding issues with
components such as compiling only one host-to-wasm trampoline per
signature instead of possibly once-per-module. Additionally the
`SignatureCollection` registration now happens once-per-component
instead of once-per-module-within-a-component.
* Fix compile errors from prior commits
* Support AOT-compiling components
This commit adds support for AOT-compiled components in the same manner
as `Module`, specifically adding:
* `Engine::precompile_component`
* `Component::serialize`
* `Component::deserialize`
* `Component::deserialize_file`
Internally the support for components looks quite similar to `Module`.
All the prior commits to this made adding the support here
(unsurprisingly) easy. Components are represented as a single object
file as are modules, and the functions for each module are all piled
into the same object file next to each other (as are areas such as data
sections). Support was also added here to quickly differentiate compiled
components vs compiled modules via the `e_flags` field in the ELF
header.
* Prevent serializing exported modules on components
The current representation of a module within a component means that the
implementation of `Module::serialize` will not work if the module is
exported from a component. The reason for this is that `serialize`
doesn't actually do anything and simply returns the underlying mmap as a
list of bytes. The mmap, however, has `.wasmtime.info` describing
component metadata as opposed to this module's metadata. While rewriting
this section could be implemented it's not so easy to do so and is
otherwise seen as not super important of a feature right now anyway.
* Fix windows build
* Fix an unused function warning
* Update crates/environ/src/compilation.rs
Co-authored-by: Nick Fitzgerald <fitzgen@gmail.com>
Co-authored-by: Nick Fitzgerald <fitzgen@gmail.com>
* Plumb type exports in components around more
This commit adds some more plumbing for type exports to ensure that they
show up in the final compiled representation of a component. For now
they continued to be ignored for all purposes in the embedding API
itself but I found this useful to explore in `wit-bindgen` based tooling
which is leveraging the component parsing in Wasmtime.
* Add a field to `ModuleTranslation` to store the original wasm
This commit adds a field to be able to refer back to the original wasm
binary for a `ModuleTranslation`. This field is used in the upcoming
support for host generation in `wit-component` to "decompile" a
component into core wasm modules to get instantiated. This is used to
extract a core wasm module from the original component.
* FIx a build warning
* allow a ComponentTypeRef::Type to point to a component TypeDef
* component matching: don't assert exported Interface type definitions are "defined"
types may be exported by their name for consumption by some component
runtimes, but in wasmtime this doesn't matter (we lift and lower to
types, not define them) so we should ignore these.
* component-model instance tests: show that an import can export a type definition
this is meaningless, but it should be accepted. (previously rejected)
* Update wasm-tools dependencies
This update brings in a number of features such as:
* The component model binary format and AST has been slightly adjusted
in a few locations. Names are dropped from parameters/results now in
the internal representation since they were not used anyway. At this
time the ability to bind a multi-return function has not been exposed.
* The `wasmparser` validator pass will now share allocations with prior
functions, providing what's probably a very minor speedup for Wasmtime
itself.
* The text format for many component-related tests now requires named
parameters.
* Some new relaxed-simd instructions are updated to be ignored.
I hope to have a follow-up to expose the multi-return ability to the
embedding API of components.
* Update audit information for new crates
* components: Limit the recursive size of types in Wasmtime
This commit is aimed at fixing #4814 by placing a hard limit on the
maximal recursive depth a type may have in the component model. The
component model theoretically allows for infinite recursion but many
various types of operations within the component model are naturally
written as recursion over the structure of a type which can lead to
stack overflow with deeply recursive types. Some examples of recursive
operations are:
* Lifting and lowering a type - currently the recursion here is modeled
in Rust directly with `#[derive]` implementations as well as the
implementations for the `Val` type.
* Compilation of adapter trampolines which iterates over the type
structure recursively.
* Historically many various calculations like the size of a type, the
flattened representation of a type, etc, were all done recursively.
Many of these are more efficiently done via other means but it was
still natural to implement these recursively initially.
By placing a hard limit on type recursion Wasmtime won't be able to load
some otherwise-valid modules. The hope, though, is that no human-written
program is likely to ever reach this limit. This limit can be revised
and/or the locations with recursion revised if it's ever reached.
The implementation of this feature is done by generalizing the current
flattened-representation calculation which now keeps track of a type's
depth and size. The size calculation isn't used just yet but I plan to
use it in fixing #4816 and it was natural enough to write here as well.
The depth is checked after a type is translated and if it exceeds the
maximum then an error is returned.
Additionally the `Arbitrary for Type` implementation was updated to
prevent generation of a type that's too-recursive.
Closes#4814
* Remove unused size calculation
* Bump up just under the limit
* Upgrade wasm-tools crates, namely the component model
This commit pulls in the latest versions of all of the `wasm-tools`
family of crates. There were two major changes that happened in
`wasm-tools` in the meantime:
* bytecodealliance/wasm-tools#697 - this commit introduced a new API for
more efficiently reading binary operators from a wasm binary. The old
`Operator`-based reading was left in place, however, and continues to
be what Wasmtime uses. I hope to update Wasmtime in a future PR to use
this new API, but for now the biggest change is...
* bytecodealliance/wasm-tools#703 - this commit was a major update to
the component model AST. This commit almost entirely deals with the
fallout of this change.
The changes made to the component model were:
1. The `unit` type no longer exists. This was generally a simple change
where the `Unit` case in a few different locations were all removed.
2. The `expected` type was renamed to `result`. This similarly was
relatively lightweight and mostly just a renaming on the surface. I
took this opportunity to rename `val::Result` to `val::ResultVal` and
`types::Result` to `types::ResultType` to avoid clashing with the
standard library types. The `Option`-based types were handled with
this as well.
3. The payload type of `variant` and `result` types are now optional.
This affected many locations that calculate flat type
representations, ABI information, etc. The `#[derive(ComponentType)]`
macro now specifically handles Rust-defined `enum` types which have
no payload to the equivalent in the component model.
4. Functions can now return multiple parameters. This changed the
signature of invoking component functions because the return value is
now bound by `ComponentNamedList` (renamed from `ComponentParams`).
This had a large effect in the tests, fuzz test case generation, etc.
5. Function types with 2-or-more parameters/results must uniquely name
all parameters/results. This mostly affected the text format used
throughout the tests.
I haven't added specifically new tests for multi-return but I changed a
number of tests to use it. Additionally I've updated the fuzzers to all
exercise multi-return as well so I think we should get some good
coverage with that.
* Update version numbers
* Use crates.io
* Optimize flat type representation calculations
Previously calculating the flat type representation would be done
recursively for an entire type tree every time it was visited.
Additionally the flat type representation was entirely built only to be
thrown away if it was too large at the end. This chiefly presented a
source of recursion based on the type structure in the component model
which fuzzing does not like as it reports stack overflows.
This commit overhauls the representation of flat types in Wasmtime by
caching the representation for each type in the compile-time
`ComponentTypesBuilder` structure. This avoids recalculating each time
the flat representation is queried and additionally allows opportunity
to have more short-circuiting to avoid building overly-large vectors.
* Remove duplicate flat count calculation in wasmtime
Roughly share the infrastructure in the `wasmtime-environ` crate, namely
the non-recursive and memoizing nature of the calculation.
* Fix component fuzz build
* Fix example compile
This commit is an effort to reduce the amount of complexity around
managing the size/alignment calculations of types in the canonical ABI.
Previously the logic for the size/alignment of a type was spread out
across a number of locations. While each individual calculation is not
really the most complicated thing in the world having the duplication in
so many places was constantly worrying me.
I've opted in this commit to centralize all of this within the runtime
at least, and now there's only one "duplicate" of this information in
the fuzzing infrastructure which is to some degree less important to
deduplicate. This commit introduces a new `CanonicalAbiInfo` type to
house all abi size/align information for both memory32 and memory64.
This new type is then used pervasively throughout fused adapter
compilation, dynamic `Val` management, and typed functions. This type
was also able to reduce the complexity of the macro-generated code
meaning that even `wasmtime-component-macro` is performing less math
than it was before.
One other major feature of this commit is that this ABI information is
now saved within a `ComponentTypes` structure. This avoids recursive
querying of size/align information frequently and instead effectively
caching it. This was a worry I had for the fused adapter compiler which
frequently sought out size/align information and would recursively
descend each type tree each time. The `fact-valid-module` fuzzer is now
nearly 10x faster in terms of iterations/s which I suspect is due to
this caching.
* Implement strings in adapter modules
This commit is a hefty addition to Wasmtime's support for the component
model. This implements the final remaining type (in the current type
hierarchy) unimplemented in adapter module trampolines: strings. Strings
are the most complicated type to implement in adapter trampolines
because they are highly structured chunks of data in memory (according
to specific encodings). Additionally each lift/lower operation can
choose its own encoding for strings meaning that Wasmtime, the host, may
have to convert between any pairwise ordering of string encodings.
The `CanonicalABI.md` in the component-model repo in general specifies
all the fiddly bits of string encoding so there's not a ton of wiggle
room for Wasmtime to get creative. This PR largely "just" implements
that. The high-level architecture of this implementation is:
* Fused adapters are first identified to determine src/dst string
encodings. This statically fixes what transcoding operation is being
performed.
* The generated adapter will be responsible for managing calls to
`realloc` and performing bounds checks. The adapter itself does not
perform memory copies or validation of string contents, however.
Instead each transcoding operation is modeled as an imported function
into the adapter module. This means that the adapter module
dynamically, during compile time, determines what string transcoders
are needed. Note that an imported transcoder is not only parameterized
over the transcoding operation but additionally which memory is the
source and which is the destination.
* The imported core wasm functions are modeled as a new
`CoreDef::Transcoder` structure. These transcoders end up being small
Cranelift-compiled trampolines. The Cranelift-compiled trampoline will
load the actual base pointer of memory and add it to the relative
pointers passed as function arguments. This trampoline then calls a
transcoder "libcall" which enters Rust-defined functions for actual
transcoding operations.
* Each possible transcoding operation is implemented in Rust with a
unique name and a unique signature depending on the needs of the
transcoder. I've tried to document inline what each transcoder does.
This means that the `Module::translate_string` in adapter modules is by
far the largest translation method. The main reason for this is due to
the management around calling the imported transcoder functions in the
face of validating string pointer/lengths and performing the dance of
`realloc`-vs-transcode at the right time. I've tried to ensure that each
individual case in transcoding is documented well enough to understand
what's going on as well.
Additionally in this PR is a full implementation in the host for the
`latin1+utf16` encoding which means that both lifting and lowering host
strings now works with this encoding.
Currently the implementation of each transcoder function is likely far
from optimal. Where possible I've leaned on the standard library itself
and for latin1-related things I'm leaning on the `encoding_rs` crate. I
initially tried to implement everything with `encoding_rs` but was
unable to uniformly do so easily. For now I settled on trying to get a
known-correct (even in the face of endianness) implementation for all of
these transcoders. If an when performance becomes an issue it should be
possible to implement more optimized versions of each of these
transcoding operations.
Testing this commit has been somewhat difficult and my general plan,
like with the `(list T)` type, is to rely heavily on fuzzing to cover
the various cases here. In this PR though I've added a simple test that
pushes some statically known strings through all the pairs of encodings
between source and destination. I've attempted to pick "interesting"
strings that one way or another stress the various paths in each
transcoding operation to ideally get full branch coverage there.
Additionally a suite of "negative" tests have also been added to ensure
that validity of encoding is actually checked.
* Fix a temporarily commented out case
* Fix wasmtime-runtime tests
* Update deny.toml configuration
* Add `BSD-3-Clause` for the `encoding_rs` crate
* Remove some unused licenses
* Add an exemption for `encoding_rs` for now
* Split up the `translate_string` method
Move out all the closures and package up captured state into smaller
lists of arguments.
* Test out-of-bounds for zero-length strings
When an adapter module depends on a particular core wasm instance this
means that it actually depends on not only that instance but all prior
core wasm instances as well. This is because core wasm instances must be
instantiated in the specified order within a component and that cannot
change depending on the dataflow between adapters. This commit fixes a
possible panic from linearizing the component dfg where an adapter
module tried to depend on an instance that hadn't been instantiated yet
because the ordering dependency between core wasm instances hadn't been
modeled.
* components: ignore export aliases to types in translation.
Currently, translation is ignoring type exports from components during
translation by skipping over them before adding them to the exports map.
If a component instantiates an inner component and aliases a type export of
that instance, it will cause wasmtime to panic with a failure to find the
export in the exports map.
The fix is to add a representation for exported types to the map that is simply
ignored when encountered. This also makes it easier to track places where we
would have to support type exports in translation in the future.
* Keep type information for type exports.
This commit keeps the type information for type exports so that types can be
properly aliased from an instance export and thereby adjusting the type index
space accordingly.
* Add a simple test case for type exports for the component model.
* Add a dataflow-based representation of components
This commit updates the inlining phase of compiling a component to
creating a dataflow-based representation of a component instead of
creating a final `Component` with a linear list of initializers. This
dataflow graph is then linearized in a final step to create the actual
final `Component`.
The motivation for this commit stems primarily from my work implementing
strings in fused adapters. In doing this my plan is to defer most
low-level transcoding to the host itself rather than implementing that
in the core wasm adapter modules. This means that small
cranelift-generated trampolines will be used for adapter modules to call
which then call "transcoding libcalls". The cranelift-generated
trampolines will get raw pointers into linear memory and pass those to
the libcall which core wasm doesn't have access to when passing
arguments to an import.
Implementing this with the previous representation of a `Component` was
becoming too tricky to bear. The initialization of a transcoder needed
to happen at just the right time: before the adapter module which needed
it was instantiated but after the linear memories referenced had been
extracted into the `VMComponentContext`. The difficulty here is further
compounded by the current adapter module injection pass already being
quite complicated. Adapter modules are already renumbering the index
space of runtime instances and shuffling items around in the
`GlobalInitializer` list. Perhaps the worst part of this was that
memories could already be referenced by host function imports or exports
to the host, and if adapters referenced the same memory it shouldn't be
referenced twice in the component. This meant that `ExtractMemory`
initializers ideally needed to be shuffled around in the initializer
list to happen as early as possible instead of wherever they happened to
show up during translation.
Overall I did my best to implement the transcoders but everything always
came up short. I have decided to throw my hands up in the air and try a
completely different approach to this, namely the dataflow-based
representation in this commit. This makes it much easier to edit the
component after initial translation for injection of adapters, injection
of transcoders, adding dependencies on possibly-already-existing items,
etc. The adapter module partitioning pass in this commit was greatly
simplified to something which I believe is functionally equivalent but
is probably an order of magnitude easier to understand.
The biggest downside of this representation I believe is having a
duplicate representation of a component. The `component::info` was
largely duplicated into the `component::dfg` module in this commit.
Personally though I think this is a more appropriate tradeoff than
before because it's very easy to reason about "convert representation A
to B" code whereas it was very difficult to reason about shuffling
around `GlobalInitializer` items in optimal fashions. This may also have
a cost at compile-time in terms of shuffling data around, but my hope is
that we have lots of other low-hanging fruit to optimize if it ever
comes to that which allows keeping this easier-to-understand
representation.
Finally, to reiterate, the final representation of components is not
changed by this PR. To the runtime internals everything is still the
same.
* Fix compile of factc
* Wasmtime: Add a pointer to `VMRuntimeLimits` in component contexts
* Save exit Wasm FP and PC in component-to-host trampolines
Fixes#4535
* Add comment about why we deref the trampoline's FP
* Update some tests to use new `vmruntime_limits_*` methods
This is a collection of some minor renamings, refactorings, sharing of
code, etc. This was all discovered during my addition of string support
to adapter functions and I figured it'd be best to frontload this and
land it ahead of the full patch since it's getting complex.
This implements the `flags` type for fused adapters and converting
between modules. The main logic here is handling the variable size of
flags in addition to the masking which happens to ignore unrelated bits
when the values pass through the canonical ABI.
This commit fills out the adapter fusion compiler for the `union`,
`enum`, `option,` and `result` types. The preexisting support for
`variant` types was refactored slightly to be extensible to all of these
other types and they all now call into the same common translation code.
* Implement variant translation in fused adapters
This commit implements the most general case of variants for fused
adapter trampolines. Additionally a number of other primitive types are
filled out here to assist with testing variants. The implementation
internally was relatively straightforward given the shape of variants,
but there's room for future optimization as necessary especially around
converting locals to various types.
This commit also introduces a "one off" fuzzer for adapters to ensure
that the generated adapter is valid. I hope to extend this fuzz
generator as more types are implemented to assist in various corner
cases that might arise. For now the fuzzer simply tests that the output
wasm module is valid, not that it actually executes correctly. I hope to
integrate with a fuzzer along the lines of #4307 one day to test the
run-time-correctness of the generated adapters as well, at which point
this fuzzer would become obsolete.
Finally this commit also fixes an issue with `u8` translation where
upper bits weren't zero'd out and were passed raw across modules.
Instead smaller-than-32 types now all mask out their upper bits and do
sign-extension as appropriate for unsigned/signed variants.
* Fuzz memory64 in the new trampoline fuzzer
Currently memory64 isn't supported elsewhere in the component model
implementation of Wasmtime but the trampoline compiler seems as good a
place as any to ensure that it at least works in isolation. This plumbs
through fuzz input into a `memory64` boolean which gets fed into
compilation. Some miscellaneous bugs were fixed as a result to ensure
that memory64 trampolines all validate correctly.
* Tweak manifest for doc build
* Add initial support for fused adapter trampolines
This commit lands a significant new piece of functionality to Wasmtime's
implementation of the component model in the form of the implementation
of fused adapter trampolines. Internally within a component core wasm
modules can communicate with each other by having their exports
`canon lift`'d to get `canon lower`'d into a different component. This
signifies that two components are communicating through a statically
known interface via the canonical ABI at this time. Previously Wasmtime
was able to identify that this communication was happening but it simply
panicked with `unimplemented!` upon seeing it. This commit is the
beginning of filling out this panic location with an actual
implementation.
The implementation route chosen here for fused adapters is to use a
WebAssembly module itself for the implementation. This means that, at
compile time of a component, Wasmtime is generating core WebAssembly
modules which then get recursively compiled within Wasmtime as well. The
choice to use WebAssembly itself as the implementation of fused adapters
stems from a few motivations:
* This does not represent a significant increase in the "trusted
compiler base" of Wasmtime. Getting the Wasm -> CLIF translation
correct once is hard enough much less for an entirely different IR to
CLIF. By generating WebAssembly no new interactions with Cranelift are
added which drastically reduces the possibilities for mistakes.
* Using WebAssembly means that component adapters are insulated from
miscompilations and mistakes. If something goes wrong it's defined
well within the WebAssembly specification how it goes wrong and what
happens as a result. This means that the "blast zone" for a wrong
adapter is the component instance but not the entire host itself.
Accesses to linear memory are guaranteed to be in-bounds and otherwise
handled via well-defined traps.
* A fully-finished fused adapter compiler is expected to be a
significant and quite complex component of Wasmtime. Functionality
along these lines is expected to be needed for Web-based polyfills of
the component model and by using core WebAssembly it provides the
opportunity to share code between Wasmtime and these polyfills for the
component model.
* Finally the runtime implementation of managing WebAssembly modules is
already implemented and quite easy to integrate with, so representing
fused adapters with WebAssembly results in very little extra support
necessary for the runtime implementation of instantiating and managing
a component.
The compiler added in this commit is dubbed Wasmtime's Fused Adapter
Compiler of Trampolines (FACT) because who doesn't like deriving a name
from an acronym. Currently the trampoline compiler is limited in its
support for interface types and only supports a few primitives. I plan
on filing future PRs to flesh out the support here for all the variants
of `InterfaceType`. For now this PR is primarily focused on all of the
other infrastructure for the addition of a trampoline compiler.
With the choice to use core WebAssembly to implement fused adapters it
means that adapters need to be inserted into a module. Unfortunately
adapters cannot all go into a single WebAssembly module because adapters
themselves have dependencies which may be provided transitively through
instances that were instantiated with other adapters. This means that a
significant chunk of this PR (`adapt.rs`) is dedicated to determining
precisely which adapters go into precisely which adapter modules. This
partitioning process attempts to make large modules wherever it can to
cut down on core wasm instantiations but is likely not optimal as
it's just a simple heuristic today.
With all of this added together it's now possible to start writing
`*.wast` tests that internally have adapted modules communicating with
one another. A `fused.wast` test suite was added as part of this PR
which is the beginning of tests for the support of the fused adapter
compiler added in this PR. Currently this is primarily testing some
various topologies of adapters along with direct/indirect modes. This
will grow many more tests over time as more types are supported.
Overall I'm not 100% satisfied with the testing story of this PR. When a
test fails it's very difficult to debug since everything is written in
the text format of WebAssembly meaning there's no "conveniences" to
print out the state of the world when things go wrong and easily debug.
I think this will become even more apparent as more tests are written
for more types in subsequent PRs. At this time though I know of no
better alternative other than leaning pretty heavily on fuzz-testing to
ensure this is all exercised.
* Fix an unused field warning
* Fix tests in `wasmtime-runtime`
* Add some more tests for compiled trampolines
* Remap exports when injecting adapters
The exports of a component were accidentally left unmapped which meant
that they indexed the instance indexes pre-adapter module insertion.
* Fix typo
* Rebase conflicts
* Components: ignore type exports (for now).
This commit updates component translation to ignore type exports for now.
Components generated with `wit-component` contain type exports to give names to
types used within the component's functions based on the component's wit
definition.
The intention is to allow bindings to be generated with meaningful names
directly from a component. In the future, type exports (and imports) may be
used for more than this purpose to support things like resource types.
This commit effectively ignores type exports when translating the component as
they are not useful to executing a component at this time.
Closes#4415.
* Code review feedback.
This commit augments the current translation phase of components with
extra machinery to track the type information of component items such as
instances, components, and functions. The end goal of this commit is to
enable the `Lower` instruction to know the type of the component
function being lowered. Currently during the inlining pass where
component fusion is detected the type of the lifted function is known,
but to implement fusion entirely the type of the lowered function must
be known. Note that these two types are expected to be different to
allow for the subtyping rules specified by the component model.
For now nothing is actually done with this information other than noting
its presence in the face of a lifted-then-lowered function. My hope
though was to split this out for a separate review to avoid making a
future component-adapter-compiler-containing-PR too large.
* wasmtime: Rename host->wasm trampolines
As we introduce new types of trampolines, having clear names for our existing
trampolines will be helpful.
* Fix typo in docs for `VMCOMPONENT_MAGIC`
* wasmtime: Add criterion micro benchmarks for traps
* Bump versions of wasm-tools crates
Note that this leaves new features in the component model, outer type
aliases for core wasm types, unimplemented for now.
* Move to crates.io-based versions of tools
This commit adds support to Wasmtime for components which themselves
export instances. The support here adds new APIs for how instance
exports are accessed in the embedding API. For now this is mostly just a
first-pass where the API is somewhat confusing and has a lot of
lifetimes. I'm hoping that over time we can figure out how to simplify
this but for now it should at least be expressive enough for exploring
the exports of an instance.
* Implement `canon lower` of a `canon lift` function in the same component
This commit implements the "degenerate" logic for implementing a
function within a component that is lifted and then immediately lowered
again. In this situation the lowered function will immediately generate
a trap and doesn't need to implement anything else.
The implementation in this commit is somewhat heavyweight but I think is
probably justified moreso in future additions to the component model
rather than what exactly is here right now. It's not expected that this
"always trap" functionality will really be used all that often since it
would generally mean a buggy component, but the functionality plumbed
through here is hopefully going to be useful for implementing
component-to-component adapter trampolines.
Specifically this commit implements a strategy where the `canon.lower`'d
function is generated by Cranelift and simply has a single trap
instruction when called, doing nothing else. The main complexity comes
from juggling around all the data associated with these functions,
primarily plumbing through the traps into the `ModuleRegistry` to
ensure that the global `is_wasm_trap_pc` function returns `true` and at
runtime when we lookup information about the trap it's all readily
available (e.g. translating the trapping pc to a `TrapCode`).
* Fix non-component build
* Fix some offset calculations
* Only create one "always trap" per signature
Use an internal map to deduplicate during compilation.
Currently I don't know how we can reasonably implement this. Given all
the signatures of how we call functions and how functions are called on
the host there's no real feasible way that I know of to hook these two
up "seamlessly". This means that a component which reexports an imported
function can't be run in Wasmtime.
One of the main reasons for this is that when calling a component
function Wasmtime wants to lower arguments first and then have them
lifted when the host is called. With a reexport though there's not
actually anything to lower into so we'd sort of need something similar
to a table on the side or maybe a linear memory and that seems like it'd
get quite complicated quite quickly for not really all that much
benefit. As-such for now this simply returns a first-class error (rather
than the current panic) in situations like this.
* Implement lowered-then-lifted functions
This commit is a few features bundled into one, culminating in the
implementation of lowered-then-lifted functions for the component model.
It's probably not going to be used all that often but this is possible
within a valid component so Wasmtime needs to do something relatively
reasonable. The main things implemented in this commit are:
* Component instances are now assigned a `RuntimeComponentInstanceIndex`
to differentiate each one. This will be used in the future to detect
fusion (one instance lowering a function from another instance). For
now it's used to allocate separate `VMComponentFlags` for each
internal component instance.
* The `CoreExport<FuncIndex>` of lowered functions was changed to a
`CoreDef` since technically a lowered function can use another lowered
function as the callee. This ended up being not too difficult to plumb
through as everything else was already in place.
* A need arose to compile host-to-wasm trampolines which weren't already
present. Currently wasm in a component is always entered through a
host-to-wasm trampoline but core wasm modules are the source of all
the trampolines. In the case of a lowered-then-lifted function there
may not actually be any core wasm modules, so component objects now
contain necessary trampolines not otherwise provided by the core wasm
objects. This feature required splitting a new function into the
`Compiler` trait for creating a host-to-wasm trampoline. After doing
this core wasm compilation was also updated to leverage this which
further enabled compiling trampolines in parallel as opposed to the
previous synchronous compilation.
* Review comments
This commit implements the `post-return` feature of the canonical ABI in
the component model. This attribute is an optionally-specified function
which is to be executed after the return value has been processed by the
caller to optionally clean-up the return value. This enables, for
example, returning an allocated string and the host then knows how to
clean it up to prevent memory leaks in the original module.
The API exposed in this PR changes the prior `TypedFunc::call` API in
behavior but not in its signature. Previously the `TypedFunc::call`
method would set the `may_enter` flag on the way out, but now that
operation is deferred until a new `TypedFunc::post_return` method is
called. This means that once a method on an instance is invoked then
nothing else can be done on the instance until the `post_return` method
is called. Note that the method must be called irrespective of whether
the `post-return` canonical ABI option was specified or not. Internally
wasm will be invoked if necessary.
This is a pretty wonky and unergonomic API to work with. For now I
couldn't think of a better alternative that improved on the ergonomics.
In the theory that the raw Wasmtime bindings for a component may not be
used all that heavily (instead `wit-bindgen` would largely be used) I'm
hoping that this isn't too much of an issue in the future.
cc #4185
* Add support for nested components
This commit is an implementation of a number of features of the
component model including:
* Defining nested components
* Outer aliases to components and modules
* Instantiating nested components
The implementation here is intended to be a foundational pillar of
Wasmtime's component model support since recursion and nested components
are the bread-and-butter of the component model. At a high level the
intention for the component model implementation in Wasmtime has long
been that the recursive nature of components is "erased" at compile time
to something that's more optimized and efficient to process. This commit
ended up exemplifying this quite well where the vast majority of the
internal changes here are in the "compilation" phase of a component
rather than the runtime instantiation phase. The support in the
`wasmtime` crate, the runtime instantiation support, only had minor
updates here while the internals of translation have seen heavy updates.
The `translate` module was greatly refactored here in this commit.
Previously it would, as a component is parsed, create a final
`Component` to hand off to trampoline compilation and get persisted at
runtime. Instead now it's a thin layer over `wasmparser` which simply
records a list of `LocalInitializer` entries for how to instantiate the
component and its index spaces are built. This internal representation
of the instantiation of a component is pretty close to the binary format
intentionally.
Instead of performing dataflow legwork the `translate` phase of a
component is now responsible for two primary tasks:
1. All components and modules are discovered within a component. They're
assigned `Static{Component,Module}Index` depending on where they're
found and a `{Module,}Translation` is prepared for each one. This
"flattens" the recursive structure of the binary into an indexed list
processable later.
2. The lexical scope of components is managed here to implement outer
module and component aliases. This is a significant design
implementation because when closing over an outer component or module
that item may actually be imported or something like the result of a
previous instantiation. This means that the capture of
modules and components is both a lexical concern as well as a runtime
concern. The handling of the "runtime" bits are handled in the next
phase of compilation.
The next and currently final phase of compilation is a new pass where
much of the historical code in `translate.rs` has been moved to (but
heavily refactored). The goal of compilation is to produce one "flat"
list of initializers for a component (as happens prior to this PR) and
to achieve this an "inliner" phase runs which runs through the
instantiation process at compile time to produce a list of initializers.
This `inline` module is the main addition as part of this PR and is now
the workhorse for dataflow analysis and tracking what's actually
referring to what.
During the `inline` phase the local initializers recorded in the
`translate` phase are processed, in sequence, to instantiate a
component. Definitions of items are tracked to correspond to their root
definition which allows seeing across instantiation argument boundaries
and such. Handling "upvars" for component outer aliases is handled in
the `inline` phase as well by creating state for a component whenever a
component is defined as was recorded during the `translate` phase.
Finally this phase is chiefly responsible for doing all string-based
name resolution at compile time that it can. This means that at runtime
no string maps will need to be consulted for item exports and such.
The final result of inlining is a list of "global initializers" which is
a flat list processed during instantiation time. These are almost
identical to the initializers that were processed prior to this PR.
There are certainly still more gaps of the component model to implement
but this should be a major leg up in terms of functionality that
Wasmtime implements. This commit, however leaves behind a "hole" which
is not intended to be filled in at this time, namely importing and
exporting components at the "root" level from and to the host. This is
tracked and explained in more detail as part of #4283.
cc #4185 as this completes a number of items there
* Tweak code to work on stable without warning
* Review comments
This commit updates the wasm-tools family of crates, notably pulling in
the refactorings and updates from bytecodealliance/wasm-tools#621 for
the latest iteration of the component model. This commit additionally
updates all support for the component model for these changes, notably:
* Many bits and pieces of type information was refactored. Many
`FooTypeIndex` namings are now `TypeFooIndex`. Additionally there is
now `TypeIndex` as well as `ComponentTypeIndex` for the two type index
spaces in a component.
* A number of new sections are now processed to handle the core and
component variants.
* Internal maps were split such as the `funcs` map into
`component_funcs` and `funcs` (same for `instances`).
* Canonical options are now processed individually instead of one bulk
`into` definition.
Overall this was not a major update to the internals of handling the
component model in Wasmtime. Instead this was mostly a surface-level
refactoring to make sure that everything lines up with the new binary
format for components.
* All text syntax used in tests was updated to the new syntax.
* Add a `VMComponentContext` type and create it on instantiation
This commit fills out the `wasmtime-runtime` crate's support for
`VMComponentContext` and creates it as part of the instantiation
process. This moves a few maps that were temporarily allocated in an
`InstanceData` into the `VMComponentContext` and additionally reads the
canonical options data from there instead.
This type still won't be used in its "full glory" until the lowering of
host functions is completely implemented, however, which will be coming
in a future commit.
* Remove `DerefMut` implementation
* Rebase conflicts
* Add trampoline compilation support for lowered imports
This commit adds support to the component model implementation for
compiling trampolines suitable for calling host imports. Currently this
is purely just the compilation side of things, modifying the
wasmtime-cranelift crate and additionally filling out a new
`VMComponentOffsets` type (similar to `VMOffsets`). The actual creation
of a `VMComponentContext` is still not performed and will be a
subsequent PR.
Internally though some tests are actually possible with this where we at
least assert that compilation of a component and creation of everything
in-memory doesn't panic or trip any assertions, so some tests are added
here for that as well.
* Fix some test errors
* Implement module imports into components
As a step towards implementing function imports into a component this
commit implements importing modules into a component. This fills out
missing pieces of functionality such as exporting modules as well. The
previous translation code had initial support for translating imported
modules but some of the AST type information was restructured with
feedback from this implementation, namely splitting the
`InstantiateModule` initializer into separate upvar/import variants to
clarify that the item orderings for imports are resolved differently at
runtime.
Much of this commit is also adding infrastructure for any imports at all
into a component. For example a `Linker` type (analagous to
`wasmtime::Linker`) was added here as well. For now this type is quite
limited due to the inability to define host functions (it can only work
with instances and instances-of-modules) but it's enough to start
writing `*.wast` tests which exercise lots of module-related functionality.
* Fix a warning
This commit enhances the processing of components to track all the
dataflow for the processing of `canon.lower`'d functions. At the same
time this fills out a few other missing details to component processing
such as aliasing from some kinds of component instances and similar.
The major changes contained within this are the updates the `info`
submodule which has the AST of component type information. This has been
significantly refactored to prepare for representing lowered functions
and implementing those. The major change is from an `Instantiation` list
to an `Initializer` list which abstractly represents a few other
initialization actions.
This work is split off from my main work to implement component imports
of host functions. This is incomplete in the sense that it doesn't
actually finish everything necessary to define host functions and import
them into components. Instead this is only the changes necessary at the
translation layer (so far). Consequently this commit does not have tests
and also namely doesn't actually include the `VMComponentContext`
initialization and usage. The full body of work is still a bit too messy
to PR just yet so I'm hoping that this is a slimmed-down-enough piece to
adequately be reviewed.
* components: Implement the ability to call component exports
This commit is an implementation of the typed method of calling
component exports. This is intended to represent the most efficient way
of calling a component in Wasmtime, similar to what `TypedFunc`
represents today for core wasm.
Internally this contains all the traits and implementations necessary to
invoke component exports with any type signature (e.g. arbitrary
parameters and/or results). The expectation is that for results we'll
reuse all of this infrastructure except in reverse (arguments and
results will be swapped when defining imports).
Some features of this implementation are:
* Arbitrary type hierarchies are supported
* The Rust-standard `Option`, `Result`, `String`, `Vec<T>`, and tuple
types all map down to the corresponding type in the component model.
* Basic utf-16 string support is implemented as proof-of-concept to show
what handling might look like. This will need further testing and
benchmarking.
* Arguments can be behind "smart pointers", so for example
`&Rc<Arc<[u8]>>` corresponds to `list<u8>` in interface types.
* Bulk copies from linear memory never happen unless explicitly
instructed to do so.
The goal of this commit is to create the ability to actually invoke wasm
components. This represents what is expected to be the performance
threshold for these calls where it ideally should be optimal how
WebAssembly is invoked. One major missing piece of this is a `#[derive]`
of some sort to generate Rust types for arbitrary `*.wit` types such as
custom records, variants, flags, unions, etc. The current trait impls
for tuples and `Result<T, E>` are expected to have fleshed out most of
what such a derive would look like.
There are some downsides and missing pieces to this commit and method of
calling components, however, such as:
* Passing `&[u8]` to WebAssembly is currently not optimal. Ideally this
compiles down to a `memcpy`-equivalent somewhere but that currently
doesn't happen due to all the bounds checks of copying data into
memory. I have been unsuccessful so far at getting these bounds checks
to be removed.
* There is no finalization at this time (the "post return" functionality
in the canonical ABI). Implementing this should be relatively
straightforward but at this time requires `wasmparser` changes to
catch up with the current canonical ABI.
* There is no guarantee that results of a wasm function will be
validated. As results are consumed they are validated but this means
that if function returns an invalid string which the host doesn't look
at then no trap will be generated. This is probably not the intended
semantics of hosts in the component model.
* At this time there's no support for memory64 memories, just a bunch of
`FIXME`s to get around to. It's expected that this won't be too
onerous, however. Some extra care will need to ensure that the various
methods related to size/alignment all optimize to the same thing they
do today (e.g. constants).
* The return value of a typed component function is either `T` or
`Value<T>`, and it depends on the ABI details of `T` and whether it
takes up more than one return value slot or not. This is an
ABI-implementation detail which is being forced through to the API
layer which is pretty unfortunate. For example if you say the return
value of a function is `(u8, u32)` then it's a runtime type-checking
error. I don't know of a great way to solve this at this time.
Overall I'm feeling optimistic about this trajectory of implementing
value lifting/lowering in Wasmtime. While there are a number of
downsides none seem completely insurmountable. There's naturally still a
good deal of work with the component model but this should be a
significant step up towards implementing and testing the component model.
* Review comments
* Write tests for calling functions
This commit adds a new test file for actually executing functions and
testing their results. This is not written as a `*.wast` test yet since
it's not 100% clear if that's the best way to do that for now (given
that dynamic signatures aren't supported yet). The tests themselves
could all largely be translated to `*.wast` testing in the future,
though, if supported.
Along the way a number of minor issues were fixed with lowerings with
the bugs exposed here.
* Fix an endian mistake
* Fix a typo and the `memory.fill` instruction
* Initial skeleton of some component model processing
This commit is the first of what will likely be many to implement the
component model proposal in Wasmtime. This will be structured as a
series of incremental commits, most of which haven't been written yet.
My hope is to make this incremental and over time to make this easier to
review and easier to test each step in isolation.
Here much of the skeleton of how components are going to work in
Wasmtime is sketched out. This is not a complete implementation of the
component model so it's not all that useful yet, but some things you can
do are:
* Process the type section into a representation amenable for working
with in Wasmtime.
* Process the module section and register core wasm modules.
* Process the instance section for core wasm modules.
* Process core wasm module imports.
* Process core wasm instance aliasing.
* Ability to compile a component with core wasm embedded.
* Ability to instantiate a component with no imports.
* Ability to get functions from this component.
This is already starting to diverge from the previous module linking
representation where a `Component` will try to avoid unnecessary
metadata about the component and instead internally only have the bare
minimum necessary to instantiate the module. My hope is we can avoid
constructing most of the index spaces during instantiation only for it
to all ge thrown away. Additionally I'm predicting that we'll need to
see through processing where possible to know how to generate adapters
and where they are fused.
At this time you can't actually call a component's functions, and that's
the next PR that I would like to make.
* Add tests for the component model support
This commit uses the recently updated wasm-tools crates to add tests for
the component model added in the previous commit. This involved updating
the `wasmtime-wast` crate for component-model changes. Currently the
component support there is quite primitive, but enough to at least
instantiate components and verify the internals of Wasmtime are all
working correctly. Additionally some simple tests for the embedding API
have also been added.
