Enum rustc_target::abi::call::aarch64::ParamExtension

pub enum ParamExtension {
    ExtendTo32Bits,
    NoExtension,
}

Given integer-types M and register width N (e.g. M=u16 and N=32 bits), the ParamExtension policy specifies how a uM value should be treated when passed via register or stack-slot of width N. See also rust-lang/rust#97463.

Variants

ExtendTo32Bits

Indicates that when passing an i8/i16, either as a function argument or as a return value, it must be sign-extended to 32 bits, and likewise a u8/u16 must be zero-extended to 32-bits. (This variant is here to accommodate Apple’s deviation from the usual AArch64 ABI as defined by ARM.)

See also: https://developer.apple.com/documentation/xcode/writing-arm64-code-for-apple-platforms#Pass-Arguments-to-Functions-Correctly

NoExtension

Indicates that no sign- nor zero-extension is performed: if a value of type with bitwidth M is passed as function argument or return value, then M bits are copied into the least significant M bits, and the remaining bits of the register (or word of memory) are untouched.

Trait Implementations

impl Clone for ParamExtension

fn clone(&self) -> ParamExtension

Returns a copy of the value.

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

Performs copy-assignment from source.

impl PartialEq<ParamExtension> for ParamExtension

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

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

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

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

impl Copy for ParamExtension

impl StructuralPartialEq for ParamExtension

Layout

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference’s “Type Layout” chapter for details on type layout guarantees.

Size:1 byte

Size for each variant:

• ExtendTo32Bits: 0 bytes
• NoExtension: 0 bytes