9814e8bfebcaa63e9fdbdb36f99223aa94e011ba
7 Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
Alex Crichton
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e68aa99588 |
Implement the memory64 proposal in Wasmtime (#3153)
* Implement the memory64 proposal in Wasmtime This commit implements the WebAssembly [memory64 proposal][proposal] in both Wasmtime and Cranelift. In terms of work done Cranelift ended up needing very little work here since most of it was already prepared for 64-bit memories at one point or another. Most of the work in Wasmtime is largely refactoring, changing a bunch of `u32` values to something else. A number of internal and public interfaces are changing as a result of this commit, for example: * Acessors on `wasmtime::Memory` that work with pages now all return `u64` unconditionally rather than `u32`. This makes it possible to accommodate 64-bit memories with this API, but we may also want to consider `usize` here at some point since the host can't grow past `usize`-limited pages anyway. * The `wasmtime::Limits` structure is removed in favor of minimum/maximum methods on table/memory types. * Many libcall intrinsics called by jit code now unconditionally take `u64` arguments instead of `u32`. Return values are `usize`, however, since the return value, if successful, is always bounded by host memory while arguments can come from any guest. * The `heap_addr` clif instruction now takes a 64-bit offset argument instead of a 32-bit one. It turns out that the legalization of `heap_addr` already worked with 64-bit offsets, so this change was fairly trivial to make. * The runtime implementation of mmap-based linear memories has changed to largely work in `usize` quantities in its API and in bytes instead of pages. This simplifies various aspects and reflects that mmap-memories are always bound by `usize` since that's what the host is using to address things, and additionally most calculations care about bytes rather than pages except for the very edge where we're going to/from wasm. Overall I've tried to minimize the amount of `as` casts as possible, using checked `try_from` and checked arithemtic with either error handling or explicit `unwrap()` calls to tell us about bugs in the future. Most locations have relatively obvious things to do with various implications on various hosts, and I think they should all be roughly of the right shape but time will tell. I mostly relied on the compiler complaining that various types weren't aligned to figure out type-casting, and I manually audited some of the more obvious locations. I suspect we have a number of hidden locations that will panic on 32-bit hosts if 64-bit modules try to run there, but otherwise I think we should be generally ok (famous last words). In any case I wouldn't want to enable this by default naturally until we've fuzzed it for some time. In terms of the actual underlying implementation, no one should expect memory64 to be all that fast. Right now it's implemented with "dynamic" heaps which have a few consequences: * All memory accesses are bounds-checked. I'm not sure how aggressively Cranelift tries to optimize out bounds checks, but I suspect not a ton since we haven't stressed this much historically. * Heaps are always precisely sized. This means that every call to `memory.grow` will incur a `memcpy` of memory from the old heap to the new. We probably want to at least look into `mremap` on Linux and otherwise try to implement schemes where dynamic heaps have some reserved pages to grow into to help amortize the cost of `memory.grow`. The memory64 spec test suite is scheduled to now run on CI, but as with all the other spec test suites it's really not all that comprehensive. I've tried adding more tests for basic things as I've had to implement guards for them, but I wouldn't really consider the testing adequate from just this PR itself. I did try to take care in one test to actually allocate a 4gb+ heap and then avoid running that in the pooling allocator or in emulation because otherwise that may fail or take excessively long. [proposal]: https://github.com/WebAssembly/memory64/blob/master/proposals/memory64/Overview.md * Fix some tests * More test fixes * Fix wasmtime tests * Fix doctests * Revert to 32-bit immediate offsets in `heap_addr` This commit updates the generation of addresses in wasm code to always use 32-bit offsets for `heap_addr`, and if the calculated offset is bigger than 32-bits we emit a manual add with an overflow check. * Disable memory64 for spectest fuzzing * Fix wrong offset being added to heap addr * More comments! * Clarify bytes/pages |
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Alex Crichton
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7a1b7cdf92 |
Implement RFC 11: Redesigning Wasmtime's APIs (#2897)
Implement Wasmtime's new API as designed by RFC 11. This is quite a large commit which has had lots of discussion externally, so for more information it's best to read the RFC thread and the PR thread. |
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Peter Huene
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f12b4c467c |
Add resource limiting to the Wasmtime API. (#2736)
* Add resource limiting to the Wasmtime API. This commit adds a `ResourceLimiter` trait to the Wasmtime API. When used in conjunction with `Store::new_with_limiter`, this can be used to monitor and prevent WebAssembly code from growing linear memories and tables. This is particularly useful when hosts need to take into account host resource usage to determine if WebAssembly code can consume more resources. A simple `StaticResourceLimiter` is also included with these changes that will simply limit the size of linear memories or tables for all instances created in the store based on static values. * Code review feedback. * Implemented `StoreLimits` and `StoreLimitsBuilder`. * Moved `max_instances`, `max_memories`, `max_tables` out of `Config` and into `StoreLimits`. * Moved storage of the limiter in the runtime into `Memory` and `Table`. * Made `InstanceAllocationRequest` use a reference to the limiter. * Updated docs. * Made `ResourceLimiterProxy` generic to remove a level of indirection. * Fixed the limiter not being used for `wasmtime::Memory` and `wasmtime::Table`. * Code review feedback and bug fix. * `Memory::new` now returns `Result<Self>` so that an error can be returned if the initial requested memory exceeds any limits placed on the store. * Changed an `Arc` to `Rc` as the `Arc` wasn't necessary. * Removed `Store` from the `ResourceLimiter` callbacks. Custom resource limiter implementations are free to capture any context they want, so no need to unnecessarily store a weak reference to `Store` from the proxy type. * Fixed a bug in the pooling instance allocator where an instance would be leaked from the pool. Previously, this would only have happened if the OS was unable to make the necessary linear memory available for the instance. With these changes, however, the instance might not be created due to limits placed on the store. We now properly deallocate the instance on error. * Added more tests, including one that covers the fix mentioned above. * Code review feedback. * Add another memory to `test_pooling_allocator_initial_limits_exceeded` to ensure a partially created instance is successfully deallocated. * Update some doc comments for better documentation of `Store` and `ResourceLimiter`. |
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Alex Crichton
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2697a18d2f |
Redo the statically typed Func API (#2719)
* Redo the statically typed `Func` API
This commit reimplements the `Func` API with respect to statically typed
dispatch. Previously `Func` had a `getN` and `getN_async` family of
methods which were implemented for 0 to 16 parameters. The return value
of these functions was an `impl Fn(..)` closure with the appropriate
parameters and return values.
There are a number of downsides with this approach that have become
apparent over time:
* The addition of `*_async` doubled the API surface area (which is quite
large here due to one-method-per-number-of-parameters).
* The [documentation of `Func`][old-docs] are quite verbose and feel
"polluted" with all these getters, making it harder to understand the
other methods that can be used to interact with a `Func`.
* These methods unconditionally pay the cost of returning an owned `impl
Fn` with a `'static` lifetime. While cheap, this is still paying the
cost for cloning the `Store` effectively and moving data into the
closed-over environment.
* Storage of the return value into a struct, for example, always
requires `Box`-ing the returned closure since it otherwise cannot be
named.
* Recently I had the desire to implement an "unchecked" path for
invoking wasm where you unsafely assert the type signature of a wasm
function. Doing this with today's scheme would require doubling
(again) the API surface area for both async and synchronous calls,
further polluting the documentation.
The main benefit of the previous scheme is that by returning a `impl Fn`
it was quite easy and ergonomic to actually invoke the function. In
practice, though, examples would often have something akin to
`.get0::<()>()?()?` which is a lot of things to interpret all at once.
Note that `get0` means "0 parameters" yet a type parameter is passed.
There's also a double function invocation which looks like a lot of
characters all lined up in a row.
Overall, I think that the previous design is starting to show too many
cracks and deserves a rewrite. This commit is that rewrite.
The new design in this commit is to delete the `getN{,_async}` family of
functions and instead have a new API:
impl Func {
fn typed<P, R>(&self) -> Result<&Typed<P, R>>;
}
impl Typed<P, R> {
fn call(&self, params: P) -> Result<R, Trap>;
async fn call_async(&self, params: P) -> Result<R, Trap>;
}
This should entirely replace the current scheme, albeit by slightly
losing ergonomics use cases. The idea behind the API is that the
existence of `Typed<P, R>` is a "proof" that the underlying function
takes `P` and returns `R`. The `Func::typed` method peforms a runtime
type-check to ensure that types all match up, and if successful you get
a `Typed` value. Otherwise an error is returned.
Once you have a `Typed` then, like `Func`, you can either `call` or
`call_async`. The difference with a `Typed`, however, is that the
params/results are statically known and hence these calls can be much
more efficient.
This is a much smaller API surface area from before and should greatly
simplify the `Func` documentation. There's still a problem where
`Func::wrapN_async` produces a lot of functions to document, but that's
now the sole offender. It's a nice benefit that the
statically-typed-async verisons are now expressed with an `async`
function rather than a function-returning-a-future which makes it both
more efficient and easier to understand.
The type `P` and `R` are intended to either be bare types (e.g. `i32`)
or tuples of any length (including 0). At this time `R` is only allowed
to be `()` or a bare `i32`-style type because multi-value is not
supported with a native ABI (yet). The `P`, however, can be any size of
tuples of parameters. This is also where some ergonomics are lost
because instead of `f(1, 2)` you now have to write `f.call((1, 2))`
(note the double-parens). Similarly `f()` becomes `f.call(())`.
Overall I feel that this is a better tradeoff than before. While not
universally better due to the loss in ergonomics I feel that this design
is much more flexible in terms of what you can do with the return value
and also understanding the API surface area (just less to take in).
[old-docs]: https://docs.rs/wasmtime/0.24.0/wasmtime/struct.Func.html#method.get0
* Rename Typed to TypedFunc
* Implement multi-value returns through `Func::typed`
* Fix examples in docs
* Fix some more errors
* More test fixes
* Rebasing and adding `get_typed_func`
* Updating tests
* Fix typo
* More doc tweaks
* Tweak visibility on `Func::invoke`
* Fix tests again
|
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Yury Delendik
|
15c68f2cc1 |
Disconnects Store state fields from Compiler (#1761)
* Moves CodeMemory, VMInterrupts and SignatureRegistry from Compiler * CompiledModule holds CodeMemory and GdbJitImageRegistration * Store keeps track of its JIT code * Makes "jit_int.rs" stuff Send+Sync * Adds the threads example. |
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Dan Gohman
|
9364eb1d98 |
Refactor (#1524)
* Compute instance exports on demand. Instead having instances eagerly compute a Vec of Externs, and bumping the refcount for each Extern, compute Externs on demand. This also enables `Instance::get_export` to avoid doing a linear search. This also means that the closure returned by `get0` and friends now holds an `InstanceHandle` to dynamically hold the instance live rather than being scoped to a lifetime. * Compute module imports and exports on demand too. And compute Extern::ty on demand too. * Add a utility function for computing an ExternType. * Add a utility function for looking up a function's signature. * Add a utility function for computing the ValType of a Global. * Rename wasmtime_environ::Export to EntityIndex. This helps differentiate it from other Export types in the tree, and describes what it is. * Fix a typo in a comment. * Simplify module imports and exports. * Make `Instance::exports` return the export names. This significantly simplifies the public API, as it's relatively common to need the names, and this avoids the need to do a zip with `Module::exports`. This also changes `ImportType` and `ExportType` to have public members instead of private members and accessors, as I find that simplifies the usage particularly in cases where there are temporary instances. * Remove `Instance::module`. This doesn't quite remove `Instance`'s `module` member, it gets a step closer. * Use a InstanceHandle utility function. * Don't consume self in the `Func::get*` methods. Instead, just create a closure containing the instance handle and the export for them to call. * Use `ExactSizeIterator` to avoid needing separate `num_*` methods. * Rename `Extern::func()` etc. to `into_func()` etc. * Revise examples to avoid using `nth`. * Add convenience methods to instance for getting specific extern types. * Use the convenience functions in more tests and examples. * Avoid cloning strings for `ImportType` and `ExportType`. * Remove more obviated clone() calls. * Simplify `Func`'s closure state. * Make wasmtime::Export's fields private. This makes them more consistent with ExportType. * Fix compilation error. * Make a lifetime parameter explicit, and use better lifetime names. Instead of 'me, use 'instance and 'module to make it clear what the lifetime is. * More lifetime cleanups. |
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Alex Crichton
|
3c51d3adb8 |
Move all examples to a top-level directory (#1286)
* Move all examples to a top-level directory This commit moves all API examples (Rust and C) to a top-level `examples` directory. This is intended to make it more discoverable and conventional as to where examples are located. Additionally all examples are now available in both Rust and C to see how to execute the example in the language you're familiar with. The intention is that as more languages are supported we'd add more languages as examples here too. Each example is also accompanied by either a `*.wat` file which is parsed as input, or a Rust project in a `wasm` folder which is compiled as input. A simple driver crate was also added to `crates/misc` which executes all the examples on CI, ensuring the C and Rust examples all execute successfully. |