Update LLVM to 21.1.2

[dianqk]

Fixes #146065.

[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 p=1

[bors]

📌 Commit 95ddfa1 has been approved by cuviper

It is now in the queue for this repository.

[bors]

⌛ Testing commit 95ddfa1 with merge 3e887f5...

[bors]

☀️ Test successful - checks-actions
Approved by: cuviper
Pushing 3e887f5 to master...

[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 ae12bc2 (parent) -> 3e887f5 (this PR)

Test differences

Show 6 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 (we want LLVM/LLD to be built with zstd support)) (J0)
• [assembly] tests/assembly-llvm/nvptx-safe-naming.rs#LLVM20: ignore (ignored when the LLVM version (21.1.1) is newer than majorversion 20) -> ignore (ignored when the LLVM version (21.1.2) is newer than majorversion 20) (J1)
• [codegen] tests/codegen-llvm/enum/enum-discriminant-eq.rs#LLVM20: ignore (ignored when the LLVM version (21.1.1) is newer than majorversion 20) -> ignore (ignored when the LLVM version (21.1.2) is newer than majorversion 20) (J1)
• [ui] tests/ui/sanitizer/kcfi-arity-requires-llvm-21-0-0.rs: ignore (ignored when the LLVM version (21.1.1) is newer than majorversion 20) -> ignore (ignored when the LLVM version (21.1.2) is newer than majorversion 20) (J2)

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

Job group index

• J0: x86_64-gnu-nopt
• J1: aarch64-apple, aarch64-gnu, aarch64-msvc-1, arm-android, armhf-gnu, dist-i586-gnu-i586-i686-musl, i686-gnu-1, i686-gnu-nopt-1, i686-msvc-1, test-various, x86_64-gnu, x86_64-gnu-nopt, x86_64-gnu-stable, x86_64-mingw-1, x86_64-msvc-1
• J2: aarch64-apple, aarch64-gnu, aarch64-msvc-1, arm-android, armhf-gnu, dist-i586-gnu-i586-i686-musl, i686-gnu-1, i686-gnu-nopt-1, i686-msvc-1, test-various, x86_64-gnu, x86_64-gnu-debug, x86_64-gnu-nopt, x86_64-gnu-stable, x86_64-mingw-1, x86_64-msvc-1

Test dashboard

Run

cargo run --manifest-path src/ci/citool/Cargo.toml -- \
    test-dashboard 3e887f5faa673bd1f9f6c95fc5d201598818add4 --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. pr-check-1: 1384.2s -> 4374.7s (216.1%)
2. dist-arm-linux-musl: 5490.8s -> 16901.5s (207.8%)
3. dist-x86_64-illumos: 5645.7s -> 16672.8s (195.3%)
4. dist-x86_64-solaris: 5275.0s -> 15388.6s (191.7%)
5. dist-sparcv9-solaris: 5123.4s -> 14014.7s (173.5%)
6. pr-check-2: 2100.2s -> 5277.3s (151.3%)
7. x86_64-rust-for-linux: 2547.3s -> 6130.7s (140.7%)
8. dist-android: 1568.5s -> 3651.2s (132.8%)
9. dist-x86_64-freebsd: 5053.2s -> 11319.8s (124.0%)
10. dist-ohos-x86_64: 4324.8s -> 9669.8s (123.6%)

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]

Nominating for backport, as this fixes a number of regressions from the LLVM upgrade:

• LLVM 21 bump broke defmt strings containing escaped double-quotes #146065
• Compiletime regression for fast_transpose crate #146512
• https://bugzilla.redhat.com/show_bug.cgi?id=2396901

Full diff: rust-lang/llvm-project@3337936...8c30b9c

[rust-timer]

Finished benchmarking commit (3e887f5): comparison URL.

Overall result: ✅ improvements - no action needed

@rustbot label: -perf-regression

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
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.3%	[-0.4%, -0.3%]	3
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary -0.8%)

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

	mean	range	count
Regressions ❌ (primary)	2.0%	[2.0%, 2.0%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-3.5%	[-3.5%, -3.5%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-0.8%	[-3.5%, 2.0%]	2

Cycles

Results (primary 2.3%, secondary 3.5%)

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

	mean	range	count
Regressions ❌ (primary)	2.3%	[2.3%, 2.3%]	1
Regressions ❌ (secondary)	3.5%	[3.5%, 3.5%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	2.3%	[2.3%, 2.3%]	1

Binary size

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

Bootstrap: 470.741s -> 471.082s (0.07%)
Artifact size: 387.87 MiB -> 387.87 MiB (-0.00%)

[apiraino]

Beta backport accepted 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