* Remove global state for trap registration
There's a number of changes brought about in this commit, motivated by a
few things. One motivation was to remove an instance of using
`lazy_static!` in an effort to remove global state and encapsulate it
wherever possible. A second motivation came when investigating a
slowly-compiling wasm module (a bit too slowly) where a good chunk of
time was spent in managing trap registrations.
The specific change made here is that `TrapRegistry` is now stored
inside of a `Compiler` instead of inside a global. Additionally traps
are "bulk registered" for a module rather than one-by-one. This form of
bulk-registration allows optimizing the locks used here, where a lock is
only held for a module at-a-time instead of once-per-function.
With these changes the "unregister" logic has also been tweaked a bit
here and there to continue to work. As a nice side effect the `Compiler`
type now has one fewer field that requires actual mutability and has
been updated for multi-threaded compilation, nudging us closer to a
world where we can support multi-threaded compilation. Yay!
In terms of performance improvements, a local wasm test file that
previously took 3 seconds to compile is now 10% faster to compile,
taking ~2.7 seconds now.
* Perform trap resolution after unwinding
This avoids taking locks in signal handlers which feels a bit iffy...
* Remove `TrapRegistration::dummy()`
Avoid an case where you're trying to lookup trap information from a
dummy module for something that happened in a different module.
* Tweak some comments
The intention of the `wasmtime` crate was to disable this verifier by
default, but it looks like cranelift actually has it turned on by
default which was making our documentation incorrect!
This was discovered by seeing a number of timeouts when fuzzing. The
debug verifier is great for fuzzing, however, so fuzzing is updated to
enable this unconditionally, meaning we'll still have timeouts. For
general users though this should make the documentation correct that the
`wasmtime` crate, by default, disables the debug verifier.
Investigating a susprisingly slow-compiling module recently, it turns
out that if you create a wasm module with 40k empty functions (e.g.
`(module (func) (func) (func) ...)`) then it takes **3 seconds** to
compile and drop via the CLI locally on a Linux system. This seems like
an extraordinary amount of time for "doing nothing", and after some
profiling I found that basically all of the time was spent in
`__deregister_frame` calls.
Poking around in the source it looks like libgcc is managing some form
of linked list, and by deregistering in the LIFO order instead of FIFO
order it avoids a quadratic search of all registered functions. Now that
being said it's still pretty bad to do a linear search all the time, and
nothing will be fixed if there are *two* instances both with 40k
functions.
For now though I hope that this will patch over the performance issue
and we can figure out better ways to manage this in the future.
* Reimplement `wasmtime-wasi` on top of `wasmtime`
This commit reimplements the `wasmtime-wasi` crate on top of the
`wasmtime` API crate, instead of being placed on top of the `wasmtime-*`
family of internal crates. The purpose here is to continue to exercise
the API as well as avoid usage of internals wherever possible and
instead use the safe API as much as possible.
The `wasmtime-wasi` crate's API has been updated as part of this PR as
well. The general outline of it is now:
* Each module snapshot has a `WasiCtxBuilder`, `WasiCtx`, and `Wasi`
type.
* The `WasiCtx*` types are reexported from `wasi-common`.
* The `Wasi` type is synthesized by the `wig` crate's procedural macro
* The `Wasi` type exposes one constructor which takes a `Store` and a
`WasiCtx`, and produces a `Wasi`
* Each `Wasi` struct fields for all the exported functions in that wasi
module. They're all public an they all have type `wasmtime::Func`
* The `Wasi` type has a `get_export` method to fetch an struct field by
name.
The intention here is that we can continue to make progress on #727 by
integrating WASI construction into the `Instance::new` experience, but
it requires everything to be part of the same system!
The main oddity required by the `wasmtime-wasi` crate is that it needs
access to the caller's `memory` export, if any. This is currently done
with a bit of a hack and is expected to go away once interface types are
more fully baked in.
* Remove now no-longer-necessary APIs from `wasmtime`
* rustfmt
* Rename to from_abi
* Add some basic sanity tests for Region
This commit adds some basic sanity tests for `overlap` method
of `Region`.
* Refactor overlaps method of Region struct
This commit refactors `Region::overlaps` method.
* Add some docs
* Assert Region's len is nonzero
* generator: take an &mut GuestMemory
rather than pass the owned GuestMemory in, just give exclusive access
to it. Makes testing easier.
* tests: start transforming tests to check abi-level generated code as well
* finish lowering of test funcs
* tests: rename variables to more sensible names
* proptesting: reliably finds that we dont allow stuff to be right against end of memory!
* memory: fix off-by-one calc in GuestMemory::contains(&self, Region)
ty proptest!
also, refactored the Region::overlaps to be the same code but easier to
read.
* generator: better location information in GuestError
* testing: proptest generates memory areas, tests everything
* 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.
Whenever we enter wasm code we need to verify that the correct number
and the correct types of arguments were passed in, lest we misinterpret
bits!
Closes#52
* Add some (incomplete set) basic sanity end-to-end tests
This commit adds some (an incomplete set of) basic sanity end-to-end
tests. It uses `test.witx` to autogenerate types and module interface
functions (aka the syscalls), and tests their implementation. For
the host memory, it uses simplistic `&mut [u8]` where we have full
control of the addressing and contents.
* Add sanity test for baz interface func
This commit adds a sanity test for the `Foo::baz` interface func.
* Upcast start/len for Region to avoid overflow
* Reenable alignment checking for memory
* use an array to implement hostmemory
Co-authored-by: Pat Hickey <pat@moreproductive.org>
* Remove another thread local in `instance.rs`
This commit removes another usage of `thread_local!` in the continued
effort to centralize all thread-local state per-call (or basically state
needed for traps) in one location. This removal is targeted at the
support for custom signal handlers on instances, removing the previous
stack of instances with instead a linked list of instances.
The `with_signals_on` method is no longer necessary (since it was always
called anyway) and is inferred from the first `vmctx` argument of the
entrypoints into wasm. These functions establish a linked list of
instances on the stack, if needed, to handle signals when they happen.
This involved some refactoring where some C++ glue was moved into Rust,
so now Rust handles a bit more of the signal handling logic.
* Update some inline docs about `HandleTrap`
During creation of an `InstanceHandle` if a link error occurred (such as
an element segment doesn't fit) then the instance itself would be leaked
by accident. This commit fixes the issue by ensuring that an
`InstanceHandle` is created very quickly so if any initialization later
fails it will be cleaned up through normal destructors.
* Improve panics/traps from imported functions
This commit performs a few refactorings and fixes a bug as well. The
changes here are:
* The `thread_local!` in the `wasmtime` crate for trap information is
removed. The thread local in the `wasmtime_runtime` crate is now
leveraged to transmit trap information.
* Panics in user-provided functions are now caught explicitly to be
carried across JIT code manually. Getting Rust panics unwinding
through JIT code is pretty likely to be super tricky and difficult to
do, so in the meantime we can get by with catching panics and resuming
the panic once we've resumed in Rust code.
* Various take/record trap apis have all been removed in favor of
working directly with `Trap` objects, where the internal trap object
has been expanded slightly to encompass user-provided errors as well.
This borrows a bit #839 and otherwise will...
Closes#848
* Rename `r#return` to `ret`
