Update to LLVM 21.1.8

[nikic]

Fixes #149522.

[rustbot]

r? @cuviper

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[rustbot]

⚠️ Warning ⚠️

• Some commits in this PR modify submodules.

  If this was not intentional, see I changed a submodule on accident in the rustc dev guide.

[cuviper]

@bors r+ rollup=never

[bors]

📌 Commit f33abb1 has been approved by cuviper

It is now in the queue for this repository.

[bors]

⌛ Testing commit f33abb1 with merge f2c7087...

[bors]

☀️ Test successful - checks-actions
Approved by: cuviper
Pushing f2c7087 to main...

[github-actions]

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 58b270b (parent) -> f2c7087 (this PR)

Test differences

Show 5 test diffs

Stage 2

• [run-make] tests/run-make/compressed-debuginfo-zstd: pass -> ignore (ignored if LLVM wasn't build with zstd for ELF section compression or LLVM is not the default codegen backend) (J0)

Additionally, 4 doctest diffs were found. These are ignored, as they are noisy.

Job group index

• J0: x86_64-gnu-nopt

Test dashboard

Run

cargo run --manifest-path src/ci/citool/Cargo.toml -- \
    test-dashboard f2c70877a7dbc51cd98e2d5d25209b24d4a586d5 --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

1. x86_64-rust-for-linux: 2722.7s -> 3733.9s (+37.1%)
2. x86_64-gnu-gcc: 3066.8s -> 4094.3s (+33.5%)
3. pr-check-2: 2344.4s -> 3069.3s (+30.9%)
4. pr-check-1: 1683.4s -> 2161.9s (+28.4%)
5. x86_64-gnu-tools: 3287.4s -> 4216.0s (+28.2%)
6. x86_64-gnu-stable: 8342.6s -> 9788.8s (+17.3%)
7. arm-android: 5822.5s -> 6789.8s (+16.6%)
8. test-various: 6759.0s -> 7873.4s (+16.5%)
9. armhf-gnu: 5009.0s -> 5811.7s (+16.0%)
10. dist-aarch64-apple: 8132.9s -> 9387.0s (+15.4%)

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.

[nikic]

Beta currently has LLVM 21.1.5. The nomination is for the update to LLVM 21.1.8, including the intermediate step #149851. The full diff for both updates is: rust-lang/llvm-project@16b5ac8...85a90d1

[rust-timer]

Finished benchmarking commit (f2c7087): comparison URL.

Overall result: no relevant changes - no action needed

@rustbot label: -perf-regression

Instruction count

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

Max RSS (memory usage)

Results (primary -0.1%, secondary 0.6%)

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

	mean	range	count
Regressions ❌ (primary)	3.0%	[3.0%, 3.0%]	1
Regressions ❌ (secondary)	2.8%	[0.8%, 4.9%]	2
Improvements ✅ (primary)	-3.2%	[-3.2%, -3.2%]	1
Improvements ✅ (secondary)	-1.6%	[-2.3%, -0.8%]	2
All ❌✅ (primary)	-0.1%	[-3.2%, 3.0%]	2

Cycles

Results (primary -2.1%, secondary 2.7%)

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)	2.7%	[2.7%, 2.7%]	1
Improvements ✅ (primary)	-2.1%	[-2.1%, -2.1%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-2.1%	[-2.1%, -2.1%]	1

Binary size

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

Bootstrap: 483.187s -> 483.372s (0.04%)
Artifact size: 390.55 MiB -> 390.57 MiB (0.00%)

[apiraino]

Beta backport accepteed as per compiler team on Zulip. A backport PR will be authored by the release team at the end of the current development cycle. Backport labels handled by them.

@rustbot label +beta-accepted