Make asm label blocks safe context by nbdd0121 · Pull Request #131544 · rust-lang/rust (original) (raw)

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nbdd0121

Tracking issue: #119364

asm!() is forced to be wrapped inside unsafe. If there's no special treatment, the label blocks would also always be unsafe with no way of opting out. It was suggested that a simple fix is to make asm label blocks safe: #119364 (comment).

@rustbot labels: +A-inline-assembly +F-asm

@nbdd0121

asm!() is forced to be wrapped inside unsafe. If there's no special treatment, the label blocks would also always be unsafe with no way of opting out.

@rustbot

r? @petrochenkov

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petrochenkov

Out { expr: None, reg: _, late: _ }
| Const { value: _, span: _ }
| SymFn { value: _, span: _ }
| SymStatic { def_id: _ } => {}

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The default visitor uses visit_anon_const and visit_qpath in this place, don't you need them here?

To avoid potential mistakes, it probably makes sense to add a public fn walk_inline_asm_operand helper to intravisit.rs.

match op { Label { .. } => self.in_safety_context(SafetyContext::Safe, walk_inline_asm_operand(...)), _ => walk_inline_asm_operand(...), }

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This is the THIR visitor which doesn't have visit_anon_const and visit_qpath.

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Sorry, I never noticed the update, it's better to set the S-waiting-on-review label if a PR is waiting on review.

If this part cannot be improved, then it's good to go.

@ojeda ojeda mentioned this pull request

Nov 8, 2024

95 tasks

@petrochenkov

@bors

📌 Commit 809dc73 has been approved by petrochenkov

It is now in the queue for this repository.

@bors bors added S-waiting-on-bors

Status: Waiting on bors to run and complete tests. Bors will change the label on completion.

and removed S-waiting-on-author

Status: This is awaiting some action (such as code changes or more information) from the author.

labels

Nov 21, 2024

bors added a commit to rust-lang-ci/rust that referenced this pull request

Nov 21, 2024

@bors

…iaskrgr

Rollup of 6 pull requests

Successful merges:

r? @ghost @rustbot modify labels: rollup

rust-timer added a commit to rust-lang-ci/rust that referenced this pull request

Nov 21, 2024

@rust-timer

Rollup merge of rust-lang#131544 - nbdd0121:asm_goto_safe_block, r=petrochenkov

Make asm label blocks safe context

Tracking issue: rust-lang#119364

asm!() is forced to be wrapped inside unsafe. If there's no special treatment, the label blocks would also always be unsafe with no way of opting out. It was suggested that a simple fix is to make asm label blocks safe: rust-lang#119364 (comment).

@rustbot labels: +A-inline-assembly +F-asm

matthiaskrgr added a commit to matthiaskrgr/rust that referenced this pull request

Mar 17, 2025

@matthiaskrgr

…rcote

Stabilize asm_goto feature gate

Stabilize asm_goto feature (tracked by rust-lang#119364). The issue will remain open and be updated to track asm_goto_with_outputs.

Reference PR: rust-lang/reference#1693

Stabilization Report

This feature adds a label <block> operand type to asm!. <block> must be a block expression with type unit or never. The address of the block is substituted and the assembly may jump to the block. When block completes the asm! block returns and continues execution.

The block starts a new safety context and unsafe operations within must have additional unsafes; the effect of unsafe that surrounds asm! block is cancelled. See rust-lang#119364 (comment) and rust-lang#131544.

It's currently forbidden to use asm_goto with output operands; that is still unstable under asm_goto_with_outputs.

Example:

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

Tests:

rust-timer added a commit to rust-lang-ci/rust that referenced this pull request

Mar 17, 2025

@rust-timer

Rollup merge of rust-lang#133870 - nbdd0121:asm, r=traviscross,nnethercote

Stabilize asm_goto feature gate

Stabilize asm_goto feature (tracked by rust-lang#119364). The issue will remain open and be updated to track asm_goto_with_outputs.

Reference PR: rust-lang/reference#1693

Stabilization Report

This feature adds a label <block> operand type to asm!. <block> must be a block expression with type unit or never. The address of the block is substituted and the assembly may jump to the block. When block completes the asm! block returns and continues execution.

The block starts a new safety context and unsafe operations within must have additional unsafes; the effect of unsafe that surrounds asm! block is cancelled. See rust-lang#119364 (comment) and rust-lang#131544.

It's currently forbidden to use asm_goto with output operands; that is still unstable under asm_goto_with_outputs.

Example:

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

Tests:

github-actions bot pushed a commit to rust-lang/miri that referenced this pull request

Mar 20, 2025

@matthiaskrgr

Stabilize asm_goto feature gate

Stabilize asm_goto feature (tracked by #119364). The issue will remain open and be updated to track asm_goto_with_outputs.

Reference PR: rust-lang/reference#1693

Stabilization Report

This feature adds a label <block> operand type to asm!. <block> must be a block expression with type unit or never. The address of the block is substituted and the assembly may jump to the block. When block completes the asm! block returns and continues execution.

The block starts a new safety context and unsafe operations within must have additional unsafes; the effect of unsafe that surrounds asm! block is cancelled. See rust-lang/rust#119364 (comment) and rust-lang/rust#131544.

It's currently forbidden to use asm_goto with output operands; that is still unstable under asm_goto_with_outputs.

Example:

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

Tests:

Labels

A-inline-assembly

Area: Inline assembly (`asm!(…)`)

F-asm

`#![feature(asm)]` (not `llvm_asm`)

S-waiting-on-bors

Status: Waiting on bors to run and complete tests. Bors will change the label on completion.

T-compiler

Relevant to the compiler team, which will review and decide on the PR/issue.