Struct wasmtime_environ::WasmFuncType

pub struct WasmFuncType { /* private fields */ }

WebAssembly function type – equivalent of wasmparser’s FuncType.

Implementations

impl WasmFuncType

pub fn new(params: Box<[WasmValType]>, returns: Box<[WasmValType]>) -> Self

Creates a new function type from the provided params and returns.

pub fn params(&self) -> &[WasmValType]

Function params types.

pub fn non_i31_gc_ref_params_count(&self) -> usize

How many externrefs are in this function’s params?

pub fn returns(&self) -> &[WasmValType]

Returns params types.

pub fn non_i31_gc_ref_returns_count(&self) -> usize

How many externrefs are in this function’s returns?

pub fn is_trampoline_type(&self) -> bool

Is this function type compatible with trampoline usage in Wasmtime?

pub fn trampoline_type(&self) -> Cow<'_, Self>

Get the version of this function type that is suitable for usage as a trampoline in Wasmtime.

If this function is suitable for trampoline usage as-is, then a borrowed Cow is returned. If it must be tweaked for trampoline usage, then an owned Cow is returned.

What is a trampoline type?

All reference types in parameters and results are mapped to their nullable top type, e.g. (ref $my_struct_type) becomes (ref null any).

This allows us to share trampolines between functions whose signatures both map to the same trampoline type. It also allows the host to satisfy a Wasm module’s function import of type S with a function of type T where T <: S, even when the Wasm module never defines the type T (and might never even be able to!)

The flip side is that this adds a constraint to our trampolines: they can only pass references around (e.g. move a reference from one calling convention’s location to another’s) and may not actually inspect the references themselves (unless the trampolines start doing explicit, fallible downcasts, but if we ever need that, then we might want to redesign this stuff).

Trait Implementations

impl Clone for WasmFuncType

fn clone(&self) -> WasmFuncType

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for WasmFuncType

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for WasmFuncType

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Display for WasmFuncType

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Hash for WasmFuncType

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for WasmFuncType

fn eq(&self, other: &WasmFuncType) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Serialize for WasmFuncType

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl TypeTrace for WasmFuncType

fn trace<F, E>(&self, func: &mut F) -> Result<(), E>

where F: FnMut(EngineOrModuleTypeIndex) -> Result<(), E>,

Visit each edge.

fn trace_mut<F, E>(&mut self, func: &mut F) -> Result<(), E>

where F: FnMut(&mut EngineOrModuleTypeIndex) -> Result<(), E>,

Visit each edge, mutably.

fn trace_engine_indices<F, E>(&self, func: &mut F) -> Result<(), E>

where F: FnMut(VMSharedTypeIndex) -> Result<(), E>,

Trace all VMSharedTypeIndex edges, ignoring other edges.

fn canonicalize_for_runtime_usage<F>(&mut self, module_to_engine: &mut F)

where F: FnMut(ModuleInternedTypeIndex) -> VMSharedTypeIndex,

Canonicalize self by rewriting all type references inside self from module-level interned type indices to engine-level interned type indices.

fn is_canonicalized_for_runtime_usage(&self) -> bool

Is this type canonicalized for runtime usage?

fn canonicalize_for_hash_consing<F>( &mut self, rec_group_range: Range<ModuleInternedTypeIndex>, module_to_engine: &mut F, )

where F: FnMut(ModuleInternedTypeIndex) -> VMSharedTypeIndex,

Canonicalize self by rewriting all type references inside self from module-level interned type indices to either engine-level interned type indices or recgroup-relative indices.

fn is_canonicalized_for_hash_consing(&self) -> bool

Is this type canonicalized for hash consing?

impl Eq for WasmFuncType

impl StructuralPartialEq for WasmFuncType