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Rollup of 5 pull requests #130979

Merged
merged 13 commits into from
Sep 28, 2024
Merged

Rollup of 5 pull requests #130979

merged 13 commits into from
Sep 28, 2024

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matthiaskrgr
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Successful merges:

r? @ghost
@rustbot modify labels: rollup

Create a similar rollup

onur-ozkan and others added 13 commits September 27, 2024 16:09
- UnsafeCell: mention the term "data race", and reference the data race definition
- atomic: failing RMWs are just reads, reorder and reword docs
…=Mark-Simulacrum

atomics: allow atomic and non-atomic reads to race

We currently define our atomics in terms of C++ `atomic_ref`. That has the unfortunate side-effect of making it UB for an atomic and a non-atomic read to race (concretely, [this code](https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=d1a743774e60923db33def7fe314d754) has UB). There's really no good reason for this, all the academic models of the C++ memory model I am aware of allow this -- C++ just disallows this because of their insistence on an "object model" with typed memory, where `atomic_ref` temporarily creates an "atomic object" that may not be accesses via regular non-atomic operations.

So instead of tying our operations to `atomic_ref`, let us tie them directly to the underlying C++ memory model. I am not sure what is the best way to phrase this, so here's a first attempt.

We also carve out an exception from the "no mixed-size atomic accesses" rule to permit mixed-size atomic reads -- given that we permit mixed-size non-atomic reads, it seems odd that this would be disallowed for atomic reads. However, when an atomic write races with any other atomic operation, they must use the same size.

With this change, it is finally the case that every non-atomic access can be replaced by an atomic access without introducing UB.

Cc `@rust-lang/opsem` `@chorman0773` `@m-ou-se` `@WaffleLapkin` `@Amanieu`

Fixes rust-lang/unsafe-code-guidelines#483
…andling, r=Kobzol

simplify LLVM submodule handling

Fixes rust-lang#130906.
Only add an automatic SONAME for Rust dylibs

rust-lang#126094 added an automatic relative `SONAME` to all dynamic libraries, but it was really only needed for Rust `--crate-type="dylib"`. In Fedora, it was a surprise to see `SONAME` on `"cdylib"` libraries like Python modules, especially because that generates an undesirable RPM `Provides`. We can instead add a `SONAME` just for Rust dylibs by passing the crate-type argument farther.

Ref: https://bugzilla.redhat.com/show_bug.cgi?id=2314879
compiletest: rename "runtest/crash.rs" to "runtest/crashes.rs" to be in line with the test directory

r? jieyouxu
@rustbot rustbot added A-run-make Area: port run-make Makefiles to rmake.rs A-testsuite Area: The testsuite used to check the correctness of rustc S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-bootstrap Relevant to the bootstrap subteam: Rust's build system (x.py and src/bootstrap) 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. rollup A PR which is a rollup labels Sep 28, 2024
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@bors r+ rollup=never p=5

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bors commented Sep 28, 2024

📌 Commit 2fca8e5 has been approved by matthiaskrgr

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-review Status: Awaiting review from the assignee but also interested parties. labels Sep 28, 2024
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bors commented Sep 28, 2024

⌛ Testing commit 2fca8e5 with merge e6eb451...

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bors commented Sep 28, 2024

☀️ Test successful - checks-actions
Approved by: matthiaskrgr
Pushing e6eb451 to master...

@bors bors added the merged-by-bors This PR was explicitly merged by bors. label Sep 28, 2024
@bors bors merged commit e6eb451 into rust-lang:master Sep 28, 2024
7 checks passed
@rustbot rustbot added this to the 1.83.0 milestone Sep 28, 2024
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📌 Perf builds for each rolled up PR:

PR# Message Perf Build Sha
#128778 atomics: allow atomic and non-atomic reads to race c5de4edefdb7a4f400877829ddde8eadecac1d46 (link)
#130918 simplify LLVM submodule handling 357b80095583dbc7c2a8c71277ba1bb181322d2d (link)
#130960 Only add an automatic SONAME for Rust dylibs 90dfc7c050c299e0cedfa195c71fec2488b7bfbc (link)
#130973 compiletest: rename "runtest/crash.rs" to "runtest/crashes.… fc76bb235b1d9a7919b4b963d0a00f22b696485f (link)
#130976 remove couple redundant clones a90b4d8ec9c676fc9ce93d5d9e51afa7a5f8ee21 (link)

previous master: 612796c420

In the case of a perf regression, run the following command for each PR you suspect might be the cause: @rust-timer build $SHA

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Finished benchmarking commit (e6eb451): comparison URL.

Overall result: ❌ regressions - no action needed

@rustbot label: -perf-regression

Instruction count

This is a highly reliable metric that was used to determine the overall result at the top of this comment.

mean range count
Regressions ❌
(primary)
- - 0
Regressions ❌
(secondary)
1.7% [1.7%, 1.7%] 1
Improvements ✅
(primary)
- - 0
Improvements ✅
(secondary)
- - 0
All ❌✅ (primary) - - 0

Max RSS (memory usage)

Results (primary 1.2%, secondary 0.7%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

mean range count
Regressions ❌
(primary)
1.2% [1.2%, 1.2%] 1
Regressions ❌
(secondary)
0.7% [0.7%, 0.7%] 1
Improvements ✅
(primary)
- - 0
Improvements ✅
(secondary)
- - 0
All ❌✅ (primary) 1.2% [1.2%, 1.2%] 1

Cycles

Results (secondary 2.5%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

mean range count
Regressions ❌
(primary)
- - 0
Regressions ❌
(secondary)
2.5% [1.9%, 3.1%] 2
Improvements ✅
(primary)
- - 0
Improvements ✅
(secondary)
- - 0
All ❌✅ (primary) - - 0

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 767.487s -> 768.814s (0.17%)
Artifact size: 341.37 MiB -> 341.35 MiB (-0.01%)

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Labels
A-run-make Area: port run-make Makefiles to rmake.rs A-testsuite Area: The testsuite used to check the correctness of rustc merged-by-bors This PR was explicitly merged by bors. rollup A PR which is a rollup S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. T-bootstrap Relevant to the bootstrap subteam: Rust's build system (x.py and src/bootstrap) 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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7 participants