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[package]
name = "wasmtime-cli"
version = "0.29.0"
authors = ["The Wasmtime Project Developers"]
description = "Command-line interface for Wasmtime"
license = "Apache-2.0 WITH LLVM-exception"
documentation = "https://bytecodealliance.github.io/wasmtime/cli.html"
categories = ["wasm"]
keywords = ["webassembly", "wasm"]
repository = "https://github.com/bytecodealliance/wasmtime"
readme = "README.md"
edition = "2018"
default-run = "wasmtime"
[lib]
doctest = false
[[bin]]
name = "wasmtime"
path = "src/bin/wasmtime.rs"
doc = false
[dependencies]
Add a cranelift compile-time feature to wasmtime (#3206) * Remove unnecessary into_iter/map Forgotten from a previous refactoring, this variable was already of the right type! * Move `wasmtime_jit::Compiler` into `wasmtime` This `Compiler` struct is mostly a historical artifact at this point and wasn't necessarily pulling much weight any more. This organization also doesn't lend itself super well to compiling out `cranelift` when the `Compiler` here is used for both parallel iteration configuration settings as well as compilation. The movement into `wasmtime` is relatively small, with `Module::build_artifacts` being the main function added here which is a merging of the previous functions removed from the `wasmtime-jit` crate. * Add a `cranelift` compile-time feature to `wasmtime` This commit concludes the saga of refactoring Wasmtime and making Cranelift an optional dependency by adding a new Cargo feature to the `wasmtime` crate called `cranelift`, which is enabled by default. This feature is implemented by having a new cfg for `wasmtime` itself, `cfg(compiler)`, which is used wherever compilation is necessary. This bubbles up to disable APIs such as `Module::new`, `Func::new`, `Engine::precompile_module`, and a number of `Config` methods affecting compiler configuration. Checks are added to CI that when built in this mode Wasmtime continues to successfully build. It's hoped that although this is effectively "sprinkle `#[cfg]` until things compile" this won't be too too bad to maintain over time since it's also an use case we're interested in supporting. With `cranelift` disabled the only way to create a `Module` is with the `Module::deserialize` method, which requires some form of precompiled artifact. Two consequences of this change are: * `Module::serialize` is also disabled in this mode. The reason for this is that serialized modules contain ISA/shared flags encoded in them which were used to produce the compiled code. There's no storage for this if compilation is disabled. This could probably be re-enabled in the future if necessary, but it may not end up being all that necessary. * Deserialized modules are not checked to ensure that their ISA/shared flags are compatible with the host CPU. This is actually already the case, though, with normal modules. We'll likely want to fix this in the future using a shared implementation for both these locations. Documentation should be updated to indicate that `cranelift` can be disabled, although it's not really the most prominent documentation because this is expected to be a somewhat niche use case (albeit important, just not too common). * Always enable cranelift for the C API * Fix doc example builds * Fix check tests on GitHub Actions
3 years ago
wasmtime = { path = "crates/wasmtime", version = "0.29.0", default-features = false, features = ['cache', 'cranelift'] }
wasmtime-cache = { path = "crates/cache", version = "0.29.0" }
Add a cranelift compile-time feature to wasmtime (#3206) * Remove unnecessary into_iter/map Forgotten from a previous refactoring, this variable was already of the right type! * Move `wasmtime_jit::Compiler` into `wasmtime` This `Compiler` struct is mostly a historical artifact at this point and wasn't necessarily pulling much weight any more. This organization also doesn't lend itself super well to compiling out `cranelift` when the `Compiler` here is used for both parallel iteration configuration settings as well as compilation. The movement into `wasmtime` is relatively small, with `Module::build_artifacts` being the main function added here which is a merging of the previous functions removed from the `wasmtime-jit` crate. * Add a `cranelift` compile-time feature to `wasmtime` This commit concludes the saga of refactoring Wasmtime and making Cranelift an optional dependency by adding a new Cargo feature to the `wasmtime` crate called `cranelift`, which is enabled by default. This feature is implemented by having a new cfg for `wasmtime` itself, `cfg(compiler)`, which is used wherever compilation is necessary. This bubbles up to disable APIs such as `Module::new`, `Func::new`, `Engine::precompile_module`, and a number of `Config` methods affecting compiler configuration. Checks are added to CI that when built in this mode Wasmtime continues to successfully build. It's hoped that although this is effectively "sprinkle `#[cfg]` until things compile" this won't be too too bad to maintain over time since it's also an use case we're interested in supporting. With `cranelift` disabled the only way to create a `Module` is with the `Module::deserialize` method, which requires some form of precompiled artifact. Two consequences of this change are: * `Module::serialize` is also disabled in this mode. The reason for this is that serialized modules contain ISA/shared flags encoded in them which were used to produce the compiled code. There's no storage for this if compilation is disabled. This could probably be re-enabled in the future if necessary, but it may not end up being all that necessary. * Deserialized modules are not checked to ensure that their ISA/shared flags are compatible with the host CPU. This is actually already the case, though, with normal modules. We'll likely want to fix this in the future using a shared implementation for both these locations. Documentation should be updated to indicate that `cranelift` can be disabled, although it's not really the most prominent documentation because this is expected to be a somewhat niche use case (albeit important, just not too common). * Always enable cranelift for the C API * Fix doc example builds * Fix check tests on GitHub Actions
3 years ago
wasmtime-cranelift = { path = "crates/cranelift", version = "0.29.0" }
wasmtime-environ = { path = "crates/environ", version = "0.29.0" }
wasmtime-jit = { path = "crates/jit", version = "0.29.0" }
wasmtime-wast = { path = "crates/wast", version = "0.29.0" }
wasmtime-wasi = { path = "crates/wasi", version = "0.29.0" }
wasmtime-wasi-crypto = { path = "crates/wasi-crypto", version = "0.29.0", optional = true }
wasmtime-wasi-nn = { path = "crates/wasi-nn", version = "0.29.0", optional = true }
Use structopt instead of docopt. This commit refactors the Wasmtime CLI tools to use `structopt` instead of `docopt`. The `wasmtime` tool now has the following subcommands: * `config new` - creates a new Wasmtime configuration file. * `run` - runs a WebAssembly module. * `wasm2obj` - translates a Wasm module to native object file. * `wast` - runs a test script file. If no subcommand is specified, the `run` subcommand is used. Thus, `wasmtime foo.wasm` should continue to function as expected. The `wasm2obj` and `wast` tools still exist, but delegate to the same implementation as the `wasmtime` subcommands. The standalone `wasm2obj` and `wast` tools may be removed in the future in favor of simply using `wasmtime`. Included in this commit is a breaking change to the default Wasmtime configuration file: it has been renamed from `wasmtime-cache-config.toml` to simply `config.toml`. The new name is less specific which will allow for additional (non-cache-related) settings in the future. There are some breaking changes to improve command line UX: * The `--cache-config` option has been renamed to `--config`. * The `--create-config-file` option has moved to the `config new` subcommand. As a result, the `wasm2obj` and `wast` tools cannot be used to create a new config file. * The short form of the `--optimize` option has changed from `-o` to `-O` for consistency. * The `wasm2obj` command takes the output object file as a required positional argument rather than the former required output *option* (e.g. `wasmtime wasm2obj foo.wasm foo.obj`).
5 years ago
structopt = { version = "0.3.5", features = ["color", "suggestions"] }
object = { version = "0.26.0", default-features = false, features = ["write"] }
Migrate from failure to thiserror and anyhow (#436) * Migrate from failure to thiserror and anyhow The failure crate invents its own traits that don't use std::error::Error (because failure predates certain features added to Error); this prevents using ? on an error from failure in a function using Error. The thiserror and anyhow crates integrate with the standard Error trait instead. This change does not attempt to semantically change or refactor the approach to error-handling in any portion of the code, to ensure that the change remains straightforward to review. Modules using specific differentiated error types move from failure_derive and derive(Fail) to thiserror and derive(Error). Modules boxing all errors opaquely move from failure::Error to anyhow. Modules using String as an error type continue to do so. Code using unwrap or expect continues to do so. Drop Display implementations when thiserror can easily derive an identical instance. Drop manual traversal of iter_causes; anyhow's Debug instance prints the chain of causes by default. Use anyhow's type alias anyhow::Result<T> in place of std::result::Result<T, anyhow::Error> whenever possible. * wasm2obj: Simplify error handling using existing messages handle_module in wasm2obj manually maps cranelift_codegen::isa::LookupError values to strings, but LookupError values already have strings that say almost exactly the same thing. Rely on the strings from cranelift. * wasmtime: Rely on question-mark-in-main The main() wrapper around rmain() completely matches the behavior of question-mark-in-main (print error to stderr and return 1), so switch to question-mark-in-main. * Update to walrus 0.13 and wasm-webidl-bindings 0.6 Both crates switched from failure to anyhow; updating lets us avoid a translation from failure to anyhow within wasmtime-interface-types.
5 years ago
anyhow = "1.0.19"
target-lexicon = { version = "0.12.0", default-features = false }
pretty_env_logger = "0.4.0"
file-per-thread-logger = "0.1.1"
wat = "1.0.39"
libc = "0.2.60"
externref: implement stack map-based garbage collection For host VM code, we use plain reference counting, where cloning increments the reference count, and dropping decrements it. We can avoid many of the on-stack increment/decrement operations that typically plague the performance of reference counting via Rust's ownership and borrowing system. Moving a `VMExternRef` avoids mutating its reference count, and borrowing it either avoids the reference count increment or delays it until if/when the `VMExternRef` is cloned. When passing a `VMExternRef` into compiled Wasm code, we don't want to do reference count mutations for every compiled `local.{get,set}`, nor for every function call. Therefore, we use a variation of **deferred reference counting**, where we only mutate reference counts when storing `VMExternRef`s somewhere that outlives the activation: into a global or table. Simultaneously, we over-approximate the set of `VMExternRef`s that are inside Wasm function activations. Periodically, we walk the stack at GC safe points, and use stack map information to precisely identify the set of `VMExternRef`s inside Wasm activations. Then we take the difference between this precise set and our over-approximation, and decrement the reference count for each of the `VMExternRef`s that are in our over-approximation but not in the precise set. Finally, the over-approximation is replaced with the precise set. The `VMExternRefActivationsTable` implements the over-approximized set of `VMExternRef`s referenced by Wasm activations. Calling a Wasm function and passing it a `VMExternRef` moves the `VMExternRef` into the table, and the compiled Wasm function logically "borrows" the `VMExternRef` from the table. Similarly, `global.get` and `table.get` operations clone the gotten `VMExternRef` into the `VMExternRefActivationsTable` and then "borrow" the reference out of the table. When a `VMExternRef` is returned to host code from a Wasm function, the host increments the reference count (because the reference is logically "borrowed" from the `VMExternRefActivationsTable` and the reference count from the table will be dropped at the next GC). For more general information on deferred reference counting, see *An Examination of Deferred Reference Counting and Cycle Detection* by Quinane: https://openresearch-repository.anu.edu.au/bitstream/1885/42030/2/hon-thesis.pdf cc #929 Fixes #1804
4 years ago
log = "0.4.8"
rayon = "1.5.0"
humantime = "2.0.0"
wasmparser = "0.80.0"
lazy_static = "1.4.0"
[dev-dependencies]
env_logger = "0.8.1"
filecheck = "0.5.0"
more-asserts = "0.2.1"
tempfile = "3.1.0"
test-programs = { path = "crates/test-programs" }
wasmtime-fuzzing = { path = "crates/fuzzing" }
wasmtime-runtime = { path = "crates/runtime" }
tokio = { version = "1.8.0", features = ["rt", "time", "macros", "rt-multi-thread"] }
tracing-subscriber = "0.2.16"
wast = "37.0.0"
criterion = "0.3.4"
num_cpus = "1.13.0"
Add guard pages to the front of linear memories (#2977) * Add guard pages to the front of linear memories This commit implements a safety feature for Wasmtime to place guard pages before the allocation of all linear memories. Guard pages placed after linear memories are typically present for performance (at least) because it can help elide bounds checks. Guard pages before a linear memory, however, are never strictly needed for performance or features. The intention of a preceding guard page is to help insulate against bugs in Cranelift or other code generators, such as CVE-2021-32629. This commit adds a `Config::guard_before_linear_memory` configuration option, defaulting to `true`, which indicates whether guard pages should be present both before linear memories as well as afterwards. Guard regions continue to be controlled by `{static,dynamic}_memory_guard_size` methods. The implementation here affects both on-demand allocated memories as well as the pooling allocator for memories. For on-demand memories this adjusts the size of the allocation as well as adjusts the calculations for the base pointer of the wasm memory. For the pooling allocator this will place a singular extra guard region at the very start of the allocation for memories. Since linear memories in the pooling allocator are contiguous every memory already had a preceding guard region in memory, it was just the previous memory's guard region afterwards. Only the first memory needed this extra guard. I've attempted to write some tests to help test all this, but this is all somewhat tricky to test because the settings are pretty far away from the actual behavior. I think, though, that the tests added here should help cover various use cases and help us have confidence in tweaking the various `Config` settings beyond their defaults. Note that this also contains a semantic change where `InstanceLimits::memory_reservation_size` has been removed. Instead this field is now inferred from the `static_memory_maximum_size` and guard size settings. This should hopefully remove some duplication in these settings, canonicalizing on the guard-size/static-size settings as the way to control memory sizes and virtual reservations. * Update config docs * Fix a typo * Fix benchmark * Fix wasmtime-runtime tests * Fix some more tests * Try to fix uffd failing test * Review items * Tweak 32-bit defaults Makes the pooling allocator a bit more reasonable by default on 32-bit with these settings.
3 years ago
winapi = { version = "0.3.9", features = ['memoryapi'] }
Use an mmap-friendly serialization format (#3257) * Use an mmap-friendly serialization format This commit reimplements the main serialization format for Wasmtime's precompiled artifacts. Previously they were generally a binary blob of `bincode`-encoded metadata prefixed with some versioning information. The downside of this format, though, is that loading a precompiled artifact required pushing all information through `bincode`. This is inefficient when some data, such as trap/address tables, are rarely accessed. The new format added in this commit is one which is designed to be `mmap`-friendly. This means that the relevant parts of the precompiled artifact are already page-aligned for updating permissions of pieces here and there. Additionally the artifact is optimized so that if data is rarely read then we can delay reading it until necessary. The new artifact format for serialized modules is an ELF file. This is not a public API guarantee, so it cannot be relied upon. In the meantime though this is quite useful for exploring precompiled modules with standard tooling like `objdump`. The ELF file is already constructed as part of module compilation, and this is the main contents of the serialized artifact. THere is some extra information, though, not encoded in each module's individual ELF file such as type information. This information continues to be `bincode`-encoded, but it's intended to be much smaller and much faster to deserialize. This extra information is appended to the end of the ELF file. This means that the original ELF file is still a valid ELF file, we just get to have extra bits at the end. More information on the new format can be found in the module docs of the serialization module of Wasmtime. Another refatoring implemented as part of this commit is to deserialize and store object files directly in `mmap`-backed storage. This avoids the need to copy bytes after the artifact is loaded into memory for each compiled module, and in a future commit it opens up the door to avoiding copying the text section into a `CodeMemory`. For now, though, the main change is that copies are not necessary when loading from a precompiled compilation artifact once the artifact is itself in mmap-based memory. To assist with managing `mmap`-based memory a new `MmapVec` type was added to `wasmtime_jit` which acts as a form of `Vec<T>` backed by a `wasmtime_runtime::Mmap`. This type notably supports `drain(..N)` to slice the buffer into disjoint regions that are all separately owned, such as having a separately owned window into one artifact for all object files contained within. Finally this commit implements a small refactoring in `wasmtime-cache` to use the standard artifact format for cache entries rather than a bincode-encoded version. This required some more hooks for serializing/deserializing but otherwise the crate still performs as before. * Review comments
3 years ago
memchr = "2.4"
[build-dependencies]
anyhow = "1.0.19"
[profile.release.build-override]
opt-level = 0
[workspace]
resolver = '2'
members = [
"cranelift",
"crates/bench-api",
"crates/c-api",
Add a cranelift compile-time feature to wasmtime (#3206) * Remove unnecessary into_iter/map Forgotten from a previous refactoring, this variable was already of the right type! * Move `wasmtime_jit::Compiler` into `wasmtime` This `Compiler` struct is mostly a historical artifact at this point and wasn't necessarily pulling much weight any more. This organization also doesn't lend itself super well to compiling out `cranelift` when the `Compiler` here is used for both parallel iteration configuration settings as well as compilation. The movement into `wasmtime` is relatively small, with `Module::build_artifacts` being the main function added here which is a merging of the previous functions removed from the `wasmtime-jit` crate. * Add a `cranelift` compile-time feature to `wasmtime` This commit concludes the saga of refactoring Wasmtime and making Cranelift an optional dependency by adding a new Cargo feature to the `wasmtime` crate called `cranelift`, which is enabled by default. This feature is implemented by having a new cfg for `wasmtime` itself, `cfg(compiler)`, which is used wherever compilation is necessary. This bubbles up to disable APIs such as `Module::new`, `Func::new`, `Engine::precompile_module`, and a number of `Config` methods affecting compiler configuration. Checks are added to CI that when built in this mode Wasmtime continues to successfully build. It's hoped that although this is effectively "sprinkle `#[cfg]` until things compile" this won't be too too bad to maintain over time since it's also an use case we're interested in supporting. With `cranelift` disabled the only way to create a `Module` is with the `Module::deserialize` method, which requires some form of precompiled artifact. Two consequences of this change are: * `Module::serialize` is also disabled in this mode. The reason for this is that serialized modules contain ISA/shared flags encoded in them which were used to produce the compiled code. There's no storage for this if compilation is disabled. This could probably be re-enabled in the future if necessary, but it may not end up being all that necessary. * Deserialized modules are not checked to ensure that their ISA/shared flags are compatible with the host CPU. This is actually already the case, though, with normal modules. We'll likely want to fix this in the future using a shared implementation for both these locations. Documentation should be updated to indicate that `cranelift` can be disabled, although it's not really the most prominent documentation because this is expected to be a somewhat niche use case (albeit important, just not too common). * Always enable cranelift for the C API * Fix doc example builds * Fix check tests on GitHub Actions
3 years ago
"crates/lightbeam/wasmtime",
"crates/misc/run-examples",
"examples/fib-debug/wasm",
"examples/wasi/wasm",
"examples/tokio/wasm",
"fuzz",
]
exclude = [
'crates/wasi-common/WASI/tools/witx-cli',
'docs/rust_wasi_markdown_parser'
]
[features]
wasi-nn: turn it on by default (#2859) * wasi-nn: turn it on by default This change makes the wasi-nn Cargo feature a default feature. Previously, a wasi-nn user would have to build a separate Wasmtime binary (e.g. `cargo build --features wasi-nn ...`) to use wasi-nn and the resulting binary would require OpenVINO shared libraries to be present in the environment in order to run (otherwise it would fail immediately with linking errors). With recent changes to the `openvino` crate, the wasi-nn implementation can defer the loading of the OpenVINO shared libraries until runtime (i.e., when the user Wasm program calls `wasi_ephemeral_nn::load`) and display a user-level error if anything goes wrong (e.g., the OpenVINO libraries are not present on the system). This runtime-linking addition allows the wasi-nn feature to be turned on by default and shipped with upcoming releases of Wasmtime. This change should be transparent for users who do not use wasi-nn: the `openvino` crate is small and the newly-available wasi-nn imports only affect programs in which they are used. For those interested in reviewing the runtime linking approach added to the `openvino` crate, see https://github.com/intel/openvino-rs/pull/19. * wasi-nn spec path: don't use canonicalize * Allow dependencies using the ISC license The ISC license should be [just as permissive](https://choosealicense.com/licenses/isc) as MIT, e.g., with no additional limitations. * Add a `--wasi-modules` flag This flag controls which WASI modules are made available to the Wasm program. This initial commit enables `wasi-common` by default (equivalent to `--wasi-modules=all`) and allows `wasi-nn` and `wasi-crypto` to be added in either individually (e.g., `--wasi-modules=wasi-nn`) or as a group (e.g., `--wasi-modules=all-experimental`). * wasi-crypto: fix unused dependency Co-authored-by: Pat Hickey <pat@moreproductive.org>
4 years ago
default = ["jitdump", "wasmtime/wat", "wasmtime/parallel-compilation", "wasi-nn"]
lightbeam = ["wasmtime/lightbeam"]
jitdump = ["wasmtime/jitdump"]
vtune = ["wasmtime/vtune"]
wasi-crypto = ["wasmtime-wasi-crypto"]
wasi-nn = ["wasmtime-wasi-nn"]
uffd = ["wasmtime/uffd"]
all-arch = ["wasmtime/all-arch"]
posix-signals-on-macos = ["wasmtime/posix-signals-on-macos"]
# Stub feature that does nothing, for Cargo-features compatibility: the new
# backend is the default now.
experimental_x64 = []
# Use the old x86 backend.
Fully support multiple returns in Wasmtime (#2806) * Fully support multiple returns in Wasmtime For quite some time now Wasmtime has "supported" multiple return values, but only in the mose bare bones ways. Up until recently you couldn't get a typed version of functions with multiple return values, and never have you been able to use `Func::wrap` with functions that return multiple values. Even recently where `Func::typed` can call functions that return multiple values it uses a double-indirection by calling a trampoline which calls the real function. The underlying reason for this lack of support is that cranelift's ABI for returning multiple values is not possible to write in Rust. For example if a wasm function returns two `i32` values there is no Rust (or C!) function you can write to correspond to that. This commit, however fixes that. This commit adds two new ABIs to Cranelift: `WasmtimeSystemV` and `WasmtimeFastcall`. The intention is that these Wasmtime-specific ABIs match their corresponding ABI (e.g. `SystemV` or `WindowsFastcall`) for everything *except* how multiple values are returned. For multiple return values we simply define our own version of the ABI which Wasmtime implements, which is that for N return values the first is returned as if the function only returned that and the latter N-1 return values are returned via an out-ptr that's the last parameter to the function. These custom ABIs provides the ability for Wasmtime to bind these in Rust meaning that `Func::wrap` can now wrap functions that return multiple values and `Func::typed` no longer uses trampolines when calling functions that return multiple values. Although there's lots of internal changes there's no actual changes in the API surface area of Wasmtime, just a few more impls of more public traits which means that more types are supported in more places! Another change made with this PR is a consolidation of how the ABI of each function in a wasm module is selected. The native `SystemV` ABI, for example, is more efficient at returning multiple values than the wasmtime version of the ABI (since more things are in more registers). To continue to take advantage of this Wasmtime will now classify some functions in a wasm module with the "fast" ABI. Only functions that are not reachable externally from the module are classified with the fast ABI (e.g. those not exported, used in tables, or used with `ref.func`). This should enable purely internal functions of modules to have a faster calling convention than those which might be exposed to Wasmtime itself. Closes #1178 * Tweak some names and add docs * "fix" lightbeam compile * Fix TODO with dummy environ * Unwind info is a property of the target, not the ABI * Remove lightbeam unused imports * Attempt to fix arm64 * Document new ABIs aren't stable * Fix filetests to use the right target * Don't always do 64-bit stores with cranelift This was overwriting upper bits when 32-bit registers were being stored into return values, so fix the code inline to do a sized store instead of one-size-fits-all store. * At least get tests passing on the old backend * Fix a typo * Add some filetests with mixed abi calls * Get `multi` example working * Fix doctests on old x86 backend * Add a mixture of wasmtime/system_v tests
4 years ago
old-x86-backend = ["wasmtime/old-x86-backend"]
[badges]
maintenance = { status = "actively-developed" }
[[test]]
name = "host_segfault"
harness = false
externref: implement stack map-based garbage collection For host VM code, we use plain reference counting, where cloning increments the reference count, and dropping decrements it. We can avoid many of the on-stack increment/decrement operations that typically plague the performance of reference counting via Rust's ownership and borrowing system. Moving a `VMExternRef` avoids mutating its reference count, and borrowing it either avoids the reference count increment or delays it until if/when the `VMExternRef` is cloned. When passing a `VMExternRef` into compiled Wasm code, we don't want to do reference count mutations for every compiled `local.{get,set}`, nor for every function call. Therefore, we use a variation of **deferred reference counting**, where we only mutate reference counts when storing `VMExternRef`s somewhere that outlives the activation: into a global or table. Simultaneously, we over-approximate the set of `VMExternRef`s that are inside Wasm function activations. Periodically, we walk the stack at GC safe points, and use stack map information to precisely identify the set of `VMExternRef`s inside Wasm activations. Then we take the difference between this precise set and our over-approximation, and decrement the reference count for each of the `VMExternRef`s that are in our over-approximation but not in the precise set. Finally, the over-approximation is replaced with the precise set. The `VMExternRefActivationsTable` implements the over-approximized set of `VMExternRef`s referenced by Wasm activations. Calling a Wasm function and passing it a `VMExternRef` moves the `VMExternRef` into the table, and the compiled Wasm function logically "borrows" the `VMExternRef` from the table. Similarly, `global.get` and `table.get` operations clone the gotten `VMExternRef` into the `VMExternRefActivationsTable` and then "borrow" the reference out of the table. When a `VMExternRef` is returned to host code from a Wasm function, the host increments the reference count (because the reference is logically "borrowed" from the `VMExternRefActivationsTable` and the reference count from the table will be dropped at the next GC). For more general information on deferred reference counting, see *An Examination of Deferred Reference Counting and Cycle Detection* by Quinane: https://openresearch-repository.anu.edu.au/bitstream/1885/42030/2/hon-thesis.pdf cc #929 Fixes #1804
4 years ago
[[example]]
name = "tokio"
required-features = ["wasmtime-wasi/tokio"]
[profile.dev.package.backtrace]
debug = false # FIXME(#1813)
[[bench]]
name = "instantiation"
harness = false
[[bench]]
name = "thread_eager_init"
harness = false