wasmtime_environ::component

Enum Trampoline

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pub enum Trampoline {
    LowerImport {
        index: LoweredIndex,
        lower_ty: TypeFuncIndex,
        options: CanonicalOptions,
    },
    Transcoder {
        op: Transcode,
        from: RuntimeMemoryIndex,
        from64: bool,
        to: RuntimeMemoryIndex,
        to64: bool,
    },
    AlwaysTrap,
    ResourceNew(TypeResourceTableIndex),
    ResourceRep(TypeResourceTableIndex),
    ResourceDrop(TypeResourceTableIndex),
    ResourceTransferOwn,
    ResourceTransferBorrow,
    ResourceEnterCall,
    ResourceExitCall,
}
Expand description

A list of all possible trampolines that may be required to compile a component completely.

These trampolines are used often as core wasm definitions and require Cranelift support to generate these functions. Each trampoline serves a different purpose for implementing bits and pieces of the component model.

All trampolines have a core wasm function signature associated with them which is stored in the Component::trampolines array.

Note that this type does not implement Serialize or Deserialize and that’s intentional as this isn’t stored in the final compilation artifact.

Variants§

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LowerImport

Description of a lowered import used in conjunction with GlobalInitializer::LowerImport.

Fields

§index: LoweredIndex

The runtime lowering state that this trampoline will access.

§lower_ty: TypeFuncIndex

The type of the function that is being lowered, as perceived by the component doing the lowering.

§options: CanonicalOptions

The canonical ABI options used when lowering this function specified in the original component.

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Transcoder

Information about a string transcoding function required by an adapter module.

A transcoder is used when strings are passed between adapter modules, optionally changing string encodings at the same time. The transcoder is implemented in a few different layers:

  • Each generated adapter module has some glue around invoking the transcoder represented by this item. This involves bounds-checks and handling realloc for example.
  • Each transcoder gets a cranelift-generated trampoline which has the appropriate signature for the adapter module in question. Existence of this initializer indicates that this should be compiled by Cranelift.
  • The cranelift-generated trampoline will invoke a “transcoder libcall” which is implemented natively in Rust that has a signature independent of memory64 configuration options for example.

Fields

§op: Transcode

The transcoding operation being performed.

§from: RuntimeMemoryIndex

The linear memory that the string is being read from.

§from64: bool

Whether or not the source linear memory is 64-bit or not.

§to: RuntimeMemoryIndex

The linear memory that the string is being written to.

§to64: bool

Whether or not the destination linear memory is 64-bit or not.

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AlwaysTrap

A small adapter which simply traps, used for degenerate lift/lower combinations.

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ResourceNew(TypeResourceTableIndex)

A resource.new intrinsic which will inject a new resource into the table specified.

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ResourceRep(TypeResourceTableIndex)

Same as ResourceNew, but for the resource.rep intrinsic.

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ResourceDrop(TypeResourceTableIndex)

Same as ResourceNew, but for the resource.drop intrinsic.

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ResourceTransferOwn

An intrinsic used by FACT-generated modules which will transfer an owned resource from one table to another. Used in component-to-component adapter trampolines.

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ResourceTransferBorrow

Same as ResourceTransferOwn but for borrows.

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ResourceEnterCall

An intrinsic used by FACT-generated modules which indicates that a call is being entered and resource-related metadata needs to be configured.

Note that this is currently only invoked when borrowed resources are detected, otherwise this is “optimized out”.

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ResourceExitCall

Same as ResourceEnterCall except for when exiting a call.

Implementations§

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impl Trampoline

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pub fn symbol_name(&self) -> String

Returns the name to use for the symbol of this trampoline in the final compiled artifact

Auto Trait Implementations§

Blanket Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.