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atomic volatile: add intrinsics - #160058

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RalfJung:atomic-volatile
Aug 17, 2026
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atomic volatile: add intrinsics#160058
rust-bors[bot] merged 1 commit into
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RalfJung:atomic-volatile

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@RalfJung

@RalfJung RalfJung commented Jul 28, 2026 •
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Extend the atomic load/store intrinsics to also support volatile atomic load/store.
Tracking issue: #158947.
Library APIs that use these intrinsics will be added inn a future PR.

The GCC and cranelift implementations ignore the volatile flag, not sure how that should be implemented for them.

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rustc_codegen_gcc is developed in its own repository. If possible, consider making this change to rust-lang/rustc_codegen_gcc instead.

cc @antoyo, @GuillaumeGomez

Some changes occurred to the intrinsics. Make sure the CTFE / Miri interpreter
gets adapted for the changes, if necessary.

cc @rust-lang/miri, @oli-obk, @lcnr

rustc_codegen_cranelift is developed in its own repository. If possible, consider making this change to rust-lang/rustc_codegen_cranelift instead.

cc @bjorn3

miri is developed in its own repository. If the Miri part of this change can be broken out, consider making this change to rust-lang/miri instead. However, if Miri needs adjusting for rustc changes, just ignore this message.

cc @rust-lang/miri

@rustbot rustbot added A-LLVM Area: Code generation parts specific to LLVM. Both correctness bugs and optimization-related issues. S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Jul 28, 2026
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nia-e commented Jul 28, 2026

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library stuff looks fine, but the rest is not my prerogative :D

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Cranelift doesn't currently have a way to do volatile memory operations. In the past this was not an issue given the lack of optimizations on memory operations, but those recently got added, so volatile support now needs to be added on the Cranelift side.

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Some changes occurred to the CTFE / Miri interpreter

cc @rust-lang/miri

Some changes occurred to the CTFE machinery

cc @oli-obk, @lcnr

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@RalfJung

RalfJung commented Aug 16, 2026

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Rerolling since we have not heard from the assigned reviewer.
@rustbot reroll

@rustbot rustbot assigned JohnTitor and unassigned TaKO8Ki Aug 16, 2026
RalfJung
RalfJung commented Aug 16, 2026
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Comment thread compiler/rustc_codegen_gcc/src/builder.rs Outdated
_ty: Type<'gcc>,
ptr: RValue<'gcc>,
order: AtomicOrdering,
_volatile: bool, // FIXME we are ignoring this

@RalfJung RalfJung Aug 16, 2026 •
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cc @antoyo, @GuillaumeGomez what do you propose we do about these FIXME? How should volatile atomic operations be handled in the GCC backend?

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Usually, you make something volatile by calling make_volatile() on the type used for the operation, but it seems it is already done here.
And I don't remember why we already call make_volatile() here.

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Ah okay. I have adjusted the comment accordingly, thanks.

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This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

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JohnTitor approved these changes Aug 17, 2026
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The changes except for Cranelift look good. I'd ask for the maintainers but if it's ok to leave FIXMEs on Cranelift, feel free to r=me+(other reviewers).

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@bjorn3

bjorn3 commented Aug 17, 2026

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cg_clif changes LGTM.

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RalfJung commented Aug 17, 2026

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@bors r=JohnTitor

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bjorn3 commented Aug 17, 2026

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Github tells me "Merge status cannot be loaded", maybe that is why bors ignores it?

@bors r=JohnTitor

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There is an active github outage according to the status page.

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📌 Commit 78a3e30 has been approved by JohnTitor

It is now in the queue for this repository.

@rust-bors rust-bors Bot 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-review Status: Awaiting review from the assignee but also interested parties. labels Aug 17, 2026
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RalfJung commented Aug 17, 2026

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Yeah everything is super slow currently or doesn't load at all.

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📌 Commit 78a3e30 has been approved by JohnTitor

It is now in the queue for this repository.

JonathanBrouwer added a commit to JonathanBrouwer/rust that referenced this pull request Aug 17, 2026
@JonathanBrouwer
Rollup merge of rust-lang#160058 - RalfJung:atomic-volatile, r=JohnTitor
f54bd55 
atomic volatile: add intrinsics

Extend the atomic load/store intrinsics to also support volatile atomic load/store.
Tracking issue: rust-lang#158947.
Library APIs that use these intrinsics will be added inn a future PR.

The GCC and cranelift implementations ignore the volatile flag, not sure how that should be implemented for them.
This was referenced Aug 17, 2026
Closed
Merged
rust-bors Bot pushed a commit that referenced this pull request Aug 17, 2026
@bors
Auto merge of #161256 - JonathanBrouwer:rollup-WuI2sWX, r=JonathanBro…
8fa1c96 
…uwer

Rollup of 12 pull requests

Successful merges:

 - #161221 (`rust-analyzer` subtree update)
 - #161232 (Subtree sync for rustc_codegen_cranelift)
 - #160058 (atomic volatile: add intrinsics)
 - #161206 (Library lock file update)
 - #160905 (implement <IpAddr, SocketAddr>::unspecified_from())
 - #160986 (Move `LateParamRegion` to `rustc_type_ir`)
 - #161145 (Remove references to the obsolete `try-perf` branch)
 - #161197 (citool: update rust crates)
 - #161225 (Add regression test for lint panic on nested generic with default type param)
 - #161229 (rustc_target: couple AArch64 LLVM and cfg pauthtest ABIs)
 - #161230 (rename `#[rustc_dump_predicates]` to `#[rustc_dump_clauses]`)
 - #161237 (Remove jdno from infra-ci rotation)
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rust-bors Bot merged commit 765bc48 into rust-lang:main Aug 17, 2026
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rust-bors Bot pushed a commit that referenced this pull request Aug 17, 2026
@bors
Unrolled build for #160058
275c5b9 
Rollup merge of #160058 - RalfJung:atomic-volatile, r=JohnTitor

atomic volatile: add intrinsics

Extend the atomic load/store intrinsics to also support volatile atomic load/store.
Tracking issue: #158947.
Library APIs that use these intrinsics will be added inn a future PR.

The GCC and cranelift implementations ignore the volatile flag, not sure how that should be implemented for them.
@rustbot rustbot added this to the 1.100.0 milestone Aug 17, 2026
@RalfJung
RalfJung deleted the atomic-volatile branch August 18, 2026 08:44
@RalfJung RalfJung mentioned this pull request Aug 18, 2026
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@ojeda ojeda mentioned this pull request Aug 18, 2026
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RalfJung pushed a commit to RalfJung/miri that referenced this pull request Aug 19, 2026
@bors
Auto merge of #161256 - JonathanBrouwer:rollup-WuI2sWX, r=JonathanBro…
a87ec93 
…uwer

Rollup of 12 pull requests

Successful merges:

 - rust-lang/rust#161221 (`rust-analyzer` subtree update)
 - rust-lang/rust#161232 (Subtree sync for rustc_codegen_cranelift)
 - rust-lang/rust#160058 (atomic volatile: add intrinsics)
 - rust-lang/rust#161206 (Library lock file update)
 - rust-lang/rust#160905 (implement <IpAddr, SocketAddr>::unspecified_from())
 - rust-lang/rust#160986 (Move `LateParamRegion` to `rustc_type_ir`)
 - rust-lang/rust#161145 (Remove references to the obsolete `try-perf` branch)
 - rust-lang/rust#161197 (citool: update rust crates)
 - rust-lang/rust#161225 (Add regression test for lint panic on nested generic with default type param)
 - rust-lang/rust#161229 (rustc_target: couple AArch64 LLVM and cfg pauthtest ABIs)
 - rust-lang/rust#161230 (rename `#[rustc_dump_predicates]` to `#[rustc_dump_clauses]`)
 - rust-lang/rust#161237 (Remove jdno from infra-ci rotation)
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A-LLVM Area: Code generation parts specific to LLVM. Both correctness bugs and optimization-related issues. 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. T-libs Relevant to the library team, which will review and decide on the PR/issue.

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