Mojo trait

RegisterPassable

A marker trait to denote the type to be register passable.

The compiler treats the type that conforms to this trait with the following constraints:

the value struct doesn’t have “identity” - you can’t take the address of self on read convention methods. This is allows the compiler to pass it in registers.
The type implicitly conforms to Movable and the compiler synthesizes a trivial move constructor. The compiler needs to be able to move around values of the type by loading and storing them. A custom defined moveinit is not allowed.
Compiler checks that any stored member (vars) also conforms to this trait. It wouldn’t be possible to provide identity for a contained member if the container doesn’t have identity.
The type can choose whether it wants to be Copyable or not.

struct Foo(RegisterPassable):
   ...

Implemented traits

comptime __moveinit__is_trivial

A flag (often compiler generated) to indicate whether the implementation of __moveinit__ is trivial.

The implementation of __moveinit__ is considered to be trivial if:

The struct has a compiler-generated __moveinit__ and all its fields have a trivial __moveinit__ method.

In practice, it means the value can be moved by moving the bits from one location to another without side effects.

__moveinit__(out self: _Self, deinit existing: _Self, /)

Create a new instance of the value by moving the value of another.

Args:

Returns:

_Self