Update cc-rs to 1.2.39 by dpaoliello · Pull Request #146186 · rust-lang/rust

dpaoliello · 2025-09-04T00:06:25Z

For my purposes, contains fixes when compiling the Rust compiler for Arm64EC.

Checked the commits since 1.2.16, and I don't see anything else that may affect Rust?

find-msvc-tools was also factored out from cc to allow updating the use in rustc_codegen_ssa (finding the linker when running the Rust compiler) to be separate from the use in rustc_llvm (building LLVM as part of the Rust compiler).

rustbot · 2025-09-04T00:06:28Z

Failed to set assignee to NobodyXu: invalid assignee

Note: Only org members with at least the repository "read" role, users with write permissions, or people who have commented on the PR may be assigned.

rustbot · 2025-09-04T00:06:31Z

These commits modify the Cargo.lock file. Unintentional changes to Cargo.lock can be introduced when switching branches and rebasing PRs.

If this was unintentional then you should revert the changes before this PR is merged.
Otherwise, you can ignore this comment.

Some changes occurred in compiler/rustc_codegen_ssa

cc @WaffleLapkin

jieyouxu · 2025-09-04T01:03:49Z

@bors try jobs=aarch64-msvc-1,aarch64-apple,test-various,dist-apple-various

Update cc-rs to 1.2.33 try-job: aarch64-msvc-1 try-job: aarch64-apple try-job: test-various try-job: dist-apple-various

rust-bors · 2025-09-04T03:17:03Z

☀️ Try build successful (CI)
Build commit: d8ac12e (d8ac12e3b0cef5271092800d62ab852417973355, parent: a1208bf765ba783ee4ebdc4c29ab0a0c215806ef)

jieyouxu · 2025-09-04T14:24:37Z

Let me know @dpaoliello if you want to try with find-msvc-tools, otherwise I'm fine with the current change as well.
@rustbot author

rustbot · 2025-09-04T14:24:42Z

Reminder, once the PR becomes ready for a review, use @rustbot ready.

dpaoliello · 2025-09-04T19:00:31Z

I switched to find-msvc-tools, since I was here changing things.

@rustbot ready

rustbot · 2025-09-04T19:06:53Z

The list of allowed third-party dependencies may have been modified! You must ensure that any new dependencies have compatible licenses before merging.

cc @davidtwco, @wesleywiser

davidtwco · 2025-09-04T21:43:38Z

@bors r=davidtwco,jieyouxu

bors · 2025-09-04T21:43:41Z

📌 Commit 45a0e10 has been approved by davidtwco,jieyouxu

It is now in the queue for this repository.

bors · 2025-10-28T05:46:31Z

📌 Commit 826c925 has been approved by jieyouxu

It is now in the queue for this repository.

bors · 2025-10-28T13:25:48Z

⌛ Testing commit 826c925 with merge bc1d727...

bors · 2025-10-28T16:30:45Z

☀️ Test successful - checks-actions
Approved by: jieyouxu
Pushing bc1d727 to master...

github-actions · 2025-10-28T16:34:10Z

What is this?

This is an experimental post-merge analysis report that shows differences in test outcomes between the merged PR and its parent PR.

Comparing c9537a9 (parent) -> bc1d727 (this PR)

Test differences

Show 2 test diffs

2 doctest diffs were found. These are ignored, as they are noisy.

Test dashboard

Run

cargo run --manifest-path src/ci/citool/Cargo.toml -- \
    test-dashboard bc1d7273dfbc6f8a11c0086fa35f6748a13e8d3c --output-dir test-dashboard

And then open test-dashboard/index.html in your browser to see an overview of all executed tests.

Job duration changes

dist-loongarch64-musl: 10893.4s -> 5156.0s (-52.7%)
dist-loongarch64-linux: 11354.2s -> 5538.0s (-51.2%)
pr-check-1: 1890.9s -> 1300.6s (-31.2%)
aarch64-apple: 8224.5s -> 6892.9s (-16.2%)
armhf-gnu: 4783.2s -> 5547.6s (16.0%)
dist-apple-various: 3959.6s -> 4533.5s (14.5%)
x86_64-gnu-llvm-20-1: 3700.0s -> 3255.6s (-12.0%)
dist-i586-gnu-i586-i686-musl: 5332.8s -> 4750.4s (-10.9%)
dist-x86_64-apple: 6383.1s -> 7051.9s (10.5%)
x86_64-gnu-llvm-20-2: 5415.8s -> 5973.3s (10.3%)

How to interpret the job duration changes?

Job durations can vary a lot, based on the actual runner instance
that executed the job, system noise, invalidated caches, etc. The table above is provided
mostly for t-infra members, for simpler debugging of potential CI slow-downs.

rust-timer · 2025-10-28T17:52:14Z

Finished benchmarking commit (bc1d727): comparison URL.

Overall result: ❌ regressions - please read the text below

Our benchmarks found a performance regression caused by this PR.
This might be an actual regression, but it can also be just noise.

Next Steps:

If the regression was expected or you think it can be justified,
please write a comment with sufficient written justification, and add
@rustbot label: +perf-regression-triaged to it, to mark the regression as triaged.
If you think that you know of a way to resolve the regression, try to create
a new PR with a fix for the regression.
If you do not understand the regression or you think that it is just noise,
you can ask the @rust-lang/wg-compiler-performance working group for help (members of this group
were already notified of this PR).

@rustbot label: +perf-regression
cc @rust-lang/wg-compiler-performance

Instruction count

Our most reliable metric. Used to determine the overall result above. However, even this metric can be noisy.

	mean	range	count
Regressions ❌ (primary)	0.7%	[0.3%, 3.7%]	259
Regressions ❌ (secondary)	0.9%	[0.0%, 3.0%]	287
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.7%	[0.3%, 3.7%]	259

Max RSS (memory usage)

Results (primary -3.1%, secondary -3.9%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-3.1%	[-3.1%, -3.1%]	1
Improvements ✅ (secondary)	-3.9%	[-4.5%, -3.2%]	3
All ❌✅ (primary)	-3.1%	[-3.1%, -3.1%]	1

Cycles

Results (primary -1.9%, secondary 2.2%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	2.2%	[2.2%, 2.2%]	1
Improvements ✅ (primary)	-1.9%	[-2.5%, -1.1%]	3
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-1.9%	[-2.5%, -1.1%]	3

Binary size

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

Bootstrap: 474.143s -> 475.525s (0.29%)
Artifact size: 390.63 MiB -> 390.06 MiB (-0.14%)

jieyouxu · 2025-10-28T18:16:06Z

... I did not expect that, feel free to post a revert if this isn't noise, won't have chance to investigate until EOD tmrw.

lqd · 2025-10-28T18:46:41Z

@dpaoliello this PR wasn’t expected to impact compile-time performance this much, right?

dpaoliello · 2025-10-28T18:55:16Z

No, I wouldn't have thought so. I may have missed a change that would affect it.
@NobodyXu thoughts about the perf regression?

This reverts commit bc1d727, reversing changes made to c9537a9.

Revert "Auto merge of #146186 - dpaoliello:cc, r=jieyouxu"

madsmtm · 2025-10-30T16:08:07Z

I investigated the regression a bit, I don't think it's rustc_llvm that's the actual issue, the perf regression seem to happen on check builds as well.

A hunch could be that blake3 is compiled differently, it uses cc::Build::is_flag_supported (which changed in rust-lang/cc-rs#1424) to try to determine whether to compile C or Rust code, and it might be that one is faster than the other? Though then again, blake3 isn't used much.

Alternatively it might be tikv-jemalloc-sys, the default flags emitted there might affect it.

Kobzol · 2025-10-30T16:38:04Z

We saw similar-ish wins (in the opposite direction) when -flto started being passed to jemalloc. Maybe that regressed now?

Revert "Auto merge of #146186 - dpaoliello:cc, r=jieyouxu" This reverts #146186. This will mean regressing whichever `cc` fixes were needed for > fixes when compiling the Rust compiler for Arm64EC. It's not clear which `cc` change causes the across-the-board perf regression, I suspect it's a change in how certain compiler flags are handed. But I can immediately tell this is a rabbit hole to investigate, so let's revert for now to return-to-baseline and alleviate time pressure.

Revert "Auto merge of #146186 - dpaoliello:cc, r=jieyouxu" This reverts rust-lang/rust#146186. This will mean regressing whichever `cc` fixes were needed for > fixes when compiling the Rust compiler for Arm64EC. It's not clear which `cc` change causes the across-the-board perf regression, I suspect it's a change in how certain compiler flags are handed. But I can immediately tell this is a rabbit hole to investigate, so let's revert for now to return-to-baseline and alleviate time pressure.

Kobzol · 2025-11-03T20:49:18Z

Reverted in #148298.

@rustbot label: +perf-regression-triaged

chore: bump to cc@1.4.3 for rustc_llvm and library ### What is this? Old cc-rs derives this from the `-Clto` rustflag on its own. `cc@1.2.39` starts gating that behind `-Clinker-plugin-lto`, which bootstrap doesn't pass. Therefore, we need to pass this flag explicitly to keep LTO mode Previous efforts: * #146186 * #155438 I personally want this because of cc 1.3.0+ has the support of Cargo `-Ztrim-paths`, which helps what I am experimenting in <#161049>. ### How to review Commit by commit. To keep commits bisect-able, I added the first commit without cc bump. clang should be fine with duplicate `-flto` flags. One thing I am not certain is whether we should probe `-flto` flag in this case, or just make this fail if `-flto` isn't supported. (I assume `-flto` is quote widely supported) r? Kobzol --- 🤖 **LLM disclosure:** I used LLM for the experiment of <#161049>, but not the bootstrap LTO change in this PR.

chore: bump to cc@1.4.3 for rustc_llvm and library ### What is this? Old cc-rs derives this from the `-Clto` rustflag on its own. `cc@1.2.39` starts gating that behind `-Clinker-plugin-lto`, which bootstrap doesn't pass. Therefore, we need to pass this flag explicitly to keep LTO mode Previous efforts: * rust-lang/rust#146186 * rust-lang/rust#155438 I personally want this because of cc 1.3.0+ has the support of Cargo `-Ztrim-paths`, which helps what I am experimenting in <rust-lang/rust#161049>. ### How to review Commit by commit. To keep commits bisect-able, I added the first commit without cc bump. clang should be fine with duplicate `-flto` flags. One thing I am not certain is whether we should probe `-flto` flag in this case, or just make this fail if `-flto` isn't supported. (I assume `-flto` is quote widely supported) r? Kobzol --- 🤖 **LLM disclosure:** I used LLM for the experiment of <rust-lang/rust#161049>, but not the bootstrap LTO change in this PR.

jieyouxu self-assigned this Sep 4, 2025

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rust-bors Bot added a commit that referenced this pull request Sep 4, 2025

Auto merge of #146186 - dpaoliello:cc, r=<try>

d8ac12e

Update cc-rs to 1.2.33 try-job: aarch64-msvc-1 try-job: aarch64-apple try-job: test-various try-job: dist-apple-various

NobodyXu reviewed Sep 4, 2025

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Comment thread compiler/rustc_codegen_ssa/Cargo.toml Outdated

rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Sep 4, 2025

dpaoliello force-pushed the cc branch from 985cb6d to b8733d8 Compare September 4, 2025 18:56

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dpaoliello changed the title ~~Update cc-rs to 1.2.33~~ Update cc-rs to 1.2.33, and switch rustc_codegen_ssa to use find-msvc-tools Sep 4, 2025

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Sep 4, 2025

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dpaoliello force-pushed the cc branch from b8733d8 to 45a0e10 Compare September 4, 2025 19:06

rustbot added A-tidy Area: The tidy tool T-bootstrap Relevant to the bootstrap subteam: Rust's build system (x.py and src/bootstrap) labels Sep 4, 2025

davidtwco approved these changes Sep 4, 2025

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bors removed the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Sep 4, 2025

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 Oct 28, 2025

bors added the merged-by-bors This PR was explicitly merged by bors. label Oct 28, 2025

bors merged commit bc1d727 into rust-lang:master Oct 28, 2025
12 checks passed

rustbot added this to the 1.93.0 milestone Oct 28, 2025

rustbot added the perf-regression Performance regression. label Oct 28, 2025

dpaoliello deleted the cc branch October 28, 2025 18:36

jieyouxu added a commit to jieyouxu/rust that referenced this pull request Oct 30, 2025

Revert "Auto merge of rust-lang#146186 - dpaoliello:cc, r=jieyouxu"

2b9b7bb

This reverts commit bc1d727, reversing changes made to c9537a9.

jieyouxu mentioned this pull request Oct 30, 2025

Revert "Update cc-rs to 1.2.39 #146186" #148298

Merged

rust-bors Bot added a commit that referenced this pull request Oct 30, 2025

Auto merge of #148298 - jieyouxu:revert-cc, r=<try>

6fe122f

Revert "Auto merge of #146186 - dpaoliello:cc, r=jieyouxu"

rustbot added the perf-regression-triaged The performance regression has been triaged. label Nov 3, 2025

bjorn3 mentioned this pull request Apr 17, 2026

Update the cc crate for rustc_llvm #155438

Closed

weihanglo mentioned this pull request Aug 17, 2026

chore: bump to cc@1.4.3 for rustc_llvm and library #161260

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Test differences

Job duration changes

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rust-timer commented Oct 28, 2025

Overall result: ❌ regressions - please read the text below

Instruction count

Max RSS (memory usage)

Cycles

Binary size

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