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Tracking Issue for asm_goto_with_outputs #119364
Description
The feature gate for the issue is #![feature(asm_goto_with_outputs)].
Summary
This now tracks the with_outputs variant since #131523. asm_goto was stabilized in 1.87.
This feature adds a label<block> operand type to asm!.
Example:
unsafe {
asm!(
"jmp {}",
label {
println!("Jumped from asm!");
}
);
}The block must have unit type.
Steps
- Implementation
- Adjust documentation (see instructions on rustc-dev-guide)
- Formatting for new syntax has been added to the Style Guide (nightly-style-procedure)
- Stabilization PR (see instructions on rustc-dev-guide)
Unresolved Questions
- LLVM miscompilation for asm goto with outputs asm goto miscompilation llvm/llvm-project#74483
@rustbot labels: +A-inline-assembly +F-asm
Reacted by comex and LunaticWyrm
Reacted by Celina G. Val
Activity
Noratrieb commentedon Dec 27, 2023
Where is this coming from? Is there a lang MCP or anything like that?
nbdd0121 commentedon Dec 27, 2023
This is outlined as a future possibility in RFC2873 which I am implementing in #119365.
Auto merge of rust-lang#119365 - nbdd0121:asm-goto, r=Amanieu
Auto merge of rust-lang#119365 - nbdd0121:asm-goto, r=Amanieu
Rollup merge of rust-lang#119365 - nbdd0121:asm-goto, r=Amanieu
Rollup merge of rust-lang#119365 - nbdd0121:asm-goto, r=Amanieu
Unrolled build for rust-lang#119365
Rollup merge of rust-lang#119365 - nbdd0121:asm-goto, r=Amanieu
Rollup merge of rust-lang#119365 - nbdd0121:asm-goto, r=Amanieu
rust: upgrade to Rust 1.78.0
rust: upgrade to Rust 1.78.0
rust: upgrade to Rust 1.78.0
9 remaining items
nikomatsakis commentedon Sep 25, 2024
@nbdd0121 wrote up this document on advanced assembly usage in the Linux kernel.
Rollup merge of rust-lang#131544 - nbdd0121:asm_goto_safe_block, r=pe…
Unrolled build for rust-lang#131544
Rollup merge of rust-lang#131523 - nbdd0121:asm, r=compiler-errors
Unrolled build for rust-lang#131523
Rollup merge of rust-lang#133870 - nbdd0121:asm, r=traviscross,nnethe…
Unrolled build for rust-lang#133870
Rollup merge of #133870 - nbdd0121:asm, r=traviscross,nnethercote
programmerjake commentedon Apr 14, 2025
what happens with indirect branches to labels when stuff like IBT is in use? do labels start with
endbr64or equivalent? LLVM currently has a RFC up for removing generatedendbr64instructions to match GCC and maybe adding a way to add them back laternbdd0121 commentedon Apr 15, 2025
I think the current reading of reference isn't really clear on whether this label is allowed to be jumped to indirectly.
I don't think it'll be a huge issue for now if LLVM removes the
endbr64instruction given that this is only recently stabilized and cf-protection is not stable yet in Rust. Also, if GCC doesn't generateendbr64then a rustc_codegen_gcc probably wouldn't generateendbr64either. To allow more room for different backend implementations, I'd be inclined to say let's add a line in the Rust reference to say that the labels should only be jumped to directly if there is an architectural distinction.Mark-Simulacrum commentedon May 4, 2025
It looks like this is now the tracking issue for the with_outputs variant of the feature since #131523, so updating the title accordingly.
[-]Tracking Issue for asm_goto[/-][+]Tracking Issue for asm_goto_with_outputs[/+]rust: upgrade to Rust 1.78.0
rust: upgrade to Rust 1.78.0
jstarks commentedon Dec 13, 2025
What's necessary to stabilize the with_outputs variant? Do we need to wait until the LLVM fix is available in the oldest supported LLVM version?