Tracking issue for release notes of #133870: Stabilize asm_goto feature gate · Issue #134860 · rust-lang/rust (original) (raw)

This issue tracks the release notes text for #133870.

Steps

• Proposed text is drafted by PR author (or team) making the noteworthy change.
• Issue is nominated for release team review of clarity for wider audience.
• Release team includes text in release notes/blog posts.

Release notes text

The responsible team for the underlying change should edit this section to replace the automatically generated link with a succinct description of what changed, drawing upon text proposed by the author (either in discussion or through direct editing).

Language

• Stabilize asm_goto feature

Tip

Use the previous releases categories to help choose which one(s) to use.
The category will be de-duplicated with all the other ones by the release team.

More than one section can be included if needed.

Release blog section

If the change is notable enough for inclusion in the blog post, the responsible team should add content to this section.
Otherwise leave it empty.

Stabilization of asm_goto

The asm_goto feature is now stabilized, allowing inline assembly (asm!) to jump to labeled blocks within Rust code. This enables more flexible low-level programming, such as implementing optimized control flow in OS kernels or interacting with hardware more efficiently.

• The asm! macro now supports a label operand, which acts as a jump target.
• The label must be a block expression with a return type of () or !.
• The block executes when jumped to, and execution continues after the asm! block.
• The safety context inside the block is separate, requiring explicit unsafe markings for unsafe operations.
• Using asm_goto with output operands (asm_goto_with_outputs) remains unstable and is tracked separately.

unsafe {
    asm!(
        "jmp {}",
        label {
            println!("Jumped from asm!");
        }
    );
}

cc @nbdd0121, @tmandry -- origin issue/PR authors and assignees for starting to draft text