Enum rustc_codegen_llvm::abi::PassMode

pub enum PassMode {
    Ignore,
    Direct(ArgAttributes),
    Pair(ArgAttributes, ArgAttributes),
    Cast(Box<CastTarget, Global>, bool),
    Indirect {
        attrs: ArgAttributes,
        extra_attrs: Option<ArgAttributes>,
        on_stack: bool,
    },
}

Variants

Ignore

Ignore the argument.

The argument is either uninhabited or a ZST.

Direct(ArgAttributes)

Pass the argument directly.

The argument has a layout abi of Scalar, Vector or in rare cases Aggregate.

Pair(ArgAttributes, ArgAttributes)

Pass a pair’s elements directly in two arguments.

The argument has a layout abi of ScalarPair.

Cast(Box<CastTarget, Global>, bool)

Pass the argument after casting it, to either a single uniform or a pair of registers. The bool indicates if a Reg::i32() dummy argument is emitted before the real argument.

Indirect

Fields

attrs: ArgAttributes

extra_attrs: Option<ArgAttributes>

on_stack: bool

Pass the argument indirectly via a hidden pointer. The extra_attrs value, if any, is for the extra data (vtable or length) which indicates that it refers to an unsized rvalue. on_stack defines that the value should be passed at a fixed stack offset in accordance to the ABI rather than passed using a pointer. This corresponds to the byval LLVM argument attribute.

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: 40 bytes

Size for each variant:

• Ignore: 0 bytes
• Direct: 23 bytes
• Pair: 39 bytes
• Cast: 15 bytes
• Indirect: 39 bytes