pub enum ArgumentPurpose {
    Normal,
    StructArgument(u32),
    StructReturn,
    VMContext,
    SignatureId,
    StackLimit,
}
Expand description

The special purpose of a function argument.

Function arguments and return values are used to pass user program values between functions, but they are also used to represent special registers with significance to the ABI such as frame pointers and callee-saved registers.

The argument purpose is used to indicate any special meaning of an argument or return value.

Variants

Normal

A normal user program value passed to or from a function.

StructArgument(u32)

A C struct passed as argument.

StructReturn

Struct return pointer.

When a function needs to return more data than will fit in registers, the caller passes a pointer to a memory location where the return value can be written. In some ABIs, this struct return pointer is passed in a specific register.

This argument kind can also appear as a return value for ABIs that require a function with a StructReturn pointer argument to also return that pointer in a register.

VMContext

A VM context pointer.

This is a pointer to a context struct containing details about the current sandbox. It is used as a base pointer for vmctx global values.

SignatureId

A signature identifier.

This is a special-purpose argument used to identify the calling convention expected by the caller in an indirect call. The callee can verify that the expected signature ID matches.

StackLimit

A stack limit pointer.

This is a pointer to a stack limit. It is used to check the current stack pointer against. Can only appear once in a signature.

Trait Implementations

Returns a copy of the value. Read more

Performs copy-assignment from source. Read more

Formats the value using the given formatter. Read more

Formats the value using the given formatter. Read more

The associated error which can be returned from parsing.

Parses a string s to return a value of this type. Read more

Feeds this value into the given Hasher. Read more

Feeds a slice of this type into the given Hasher. Read more

This method tests for self and other values to be equal, and is used by ==. Read more

This method tests for !=.

Auto Trait Implementations

Blanket Implementations

Gets the TypeId of self. Read more

Immutably borrows from an owned value. Read more

Mutably borrows from an owned value. Read more

Compare self to key and return true if they are equal.

Returns the argument unchanged.

Calls U::from(self).

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

The resulting type after obtaining ownership.

Creates owned data from borrowed data, usually by cloning. Read more

🔬 This is a nightly-only experimental API. (toowned_clone_into)

Uses borrowed data to replace owned data, usually by cloning. Read more

Converts the given value to a String. Read more

The type returned in the event of a conversion error.

Performs the conversion.

The type returned in the event of a conversion error.

Performs the conversion.