Update the minimum external LLVM to 21 by cuviper · Pull Request #153684 · rust-lang/rust

cuviper · 2026-03-11T01:23:29Z

With this change, we'll have stable support for LLVM 21 and 22.
For reference, the previous increase to LLVM 20 was #145071.

cc @rust-lang/wg-llvm
r? nikic

rustbot · 2026-03-11T01:23:31Z

Some changes occurred in tests/codegen-llvm/sanitizer

cc @rcvalle

Some changes occurred in tests/ui/sanitizer

cc @rcvalle

nikic

r=me

View changes since this review

compiler/rustc_codegen_llvm/src/abi.rs

cuviper · 2026-03-11T21:00:25Z

@bors r=nikic rollup=iffy

rust-bors · 2026-03-11T21:00:28Z

📌 Commit 2c26ec1 has been approved by nikic

It is now in the queue for this repository.

Update the minimum external LLVM to 21 With this change, we'll have stable support for LLVM 21 and 22. For reference, the previous increase to LLVM 20 was #145071. cc @rust-lang/wg-llvm r? nikic

rust-bors · 2026-03-12T01:06:49Z

💔 Test for 629ea8e failed: CI. Failed job:

auto - dist-aarch64-msvc (web logs, enhanced plaintext logs)

cuviper · 2026-03-12T21:40:39Z

@bors try jobs=dist-aarch64-msvc

Update the minimum external LLVM to 21 try-job: dist-aarch64-msvc

rust-bors · 2026-03-12T23:41:14Z

☀️ Try build successful (CI)
Build commit: ab50e0e (ab50e0eed2f041e294f7600ea83722e4f2199726, parent: 801bc19d6089fed18b1ffa2f496d154da30f7a18)

cuviper · 2026-03-12T23:44:02Z

src/bootstrap/src/core/builder/cargo.rs

-                // FIXME: There is a bug in Clang 18 when building for ARM64:
-                // https://github.com/llvm/llvm-project/pull/81849. This is
-                // fixed in LLVM 19, but can't be backported.
-                if !target.starts_with("aarch64") && !target.starts_with("arm64ec") {


Looks like this is still relevant after all!

I'll rebase and squash that commit restoring it.

rustbot · 2026-03-12T23:45:55Z

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.

cuviper · 2026-03-12T23:46:33Z

@bors r=nikic

rust-bors · 2026-03-12T23:46:36Z

📌 Commit 52dfa94 has been approved by nikic

It is now in the queue for this repository.

Update the minimum external LLVM to 21 With this change, we'll have stable support for LLVM 21 and 22. For reference, the previous increase to LLVM 20 was #145071. cc @rust-lang/wg-llvm r? nikic

rust-bors · 2026-03-13T04:12:23Z

💔 Test for 5cb7716 failed: CI. Failed job:

auto - dist-x86_64-msvc (web logs, enhanced plaintext logs)

nikic · 2026-03-13T08:18:41Z

@bors retry "The hosted runner lost communication with the server."

rust-bors · 2026-03-13T13:42:09Z

☀️ Test successful - CI
Approved by: nikic
Duration: 3h 5m 21s
Pushing 8db65c7 to main...

github-actions · 2026-03-13T13:45:35Z

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 eaf4e74 (parent) -> 8db65c7 (this PR)

Test differences

Show 48 test diffs

Stage 1

[assembly] tests/assembly-llvm/nvptx-safe-naming.rs: [missing] -> ignore (only executed when the architecture is nvptx64) (J1)
[assembly] tests/assembly-llvm/nvptx-safe-naming.rs#LLVM20: ignore (ignored when the LLVM version (21.1.2) is newer than majorversion 20) -> [missing] (J1)
[assembly] tests/assembly-llvm/nvptx-safe-naming.rs#LLVM21: ignore (only executed when the architecture is nvptx64) -> [missing] (J1)
[codegen] tests/codegen-llvm/deduced-param-attrs.rs#LLVM20: ignore (ignored when the LLVM version (21.1.2) is newer than majorversion 20) -> [missing] (J1)
[codegen] tests/codegen-llvm/enum/enum-discriminant-eq.rs: [missing] -> pass (J1)
[codegen] tests/codegen-llvm/enum/enum-discriminant-eq.rs#LLVM20: ignore (ignored when the LLVM version (21.1.2) is newer than majorversion 20) -> [missing] (J1)
[codegen] tests/codegen-llvm/enum/enum-discriminant-eq.rs#LLVM21: pass -> [missing] (J1)
[codegen] tests/codegen-llvm/vec-calloc.rs: [missing] -> pass (J1)
[codegen] tests/codegen-llvm/vec-calloc.rs#llvm21: pass -> [missing] (J1)
[codegen] tests/codegen-llvm/vec-calloc.rs#normal: pass -> [missing] (J1)
[ui] tests/ui/sanitizer/kcfi-arity-requires-llvm-21-0-0.rs: ignore (ignored when the LLVM version (21.1.2) is newer than majorversion 20) -> [missing] (J1)
[codegen] tests/codegen-llvm/deduced-param-attrs.rs: [missing] -> pass (J4)
[codegen] tests/codegen-llvm/deduced-param-attrs.rs#LLVM21: pass -> [missing] (J4)
[codegen] tests/codegen-llvm/option-niche-eq.rs: [missing] -> pass (J4)
[codegen] tests/codegen-llvm/option-niche-eq.rs#LLVM21: pass -> [missing] (J4)
[codegen] tests/codegen-llvm/option-niche-eq.rs#REGULAR: pass -> [missing] (J4)
[codegen] tests/codegen-llvm/deduced-param-attrs.rs#LLVM20: ignore (ignored when the LLVM version (22.1.0) is newer than majorversion 20) -> [missing] (J7)
[codegen] tests/codegen-llvm/enum/enum-discriminant-eq.rs: [missing] -> ignore (only executed when the pointer width is 64bit) (J7)
[codegen] tests/codegen-llvm/enum/enum-discriminant-eq.rs#LLVM20: ignore (ignored when the LLVM version (22.1.0) is newer than majorversion 20) -> [missing] (J7)
[codegen] tests/codegen-llvm/enum/enum-discriminant-eq.rs#LLVM21: ignore (only executed when the pointer width is 64bit) -> [missing] (J7)
[codegen] tests/codegen-llvm/vec-calloc.rs: [missing] -> ignore (only executed when the architecture is x86_64) (J7)
[codegen] tests/codegen-llvm/vec-calloc.rs#llvm21: ignore (only executed when the architecture is x86_64) -> [missing] (J7)
[codegen] tests/codegen-llvm/vec-calloc.rs#normal: ignore (only executed when the architecture is x86_64) -> [missing] (J7)

Stage 2

[assembly] tests/assembly-llvm/nvptx-safe-naming.rs#LLVM20: ignore (ignored when the LLVM version (22.1.0) is newer than majorversion 20) -> [missing] (J0)
[codegen] tests/codegen-llvm/deduced-param-attrs.rs#LLVM20: ignore (ignored when the LLVM version (22.1.0) is newer than majorversion 20) -> [missing] (J0)
[codegen] tests/codegen-llvm/enum/enum-discriminant-eq.rs#LLVM20: ignore (ignored when the LLVM version (22.1.0) is newer than majorversion 20) -> [missing] (J0)
[codegen] tests/codegen-llvm/vec-calloc.rs: [missing] -> pass (J2)
[codegen] tests/codegen-llvm/vec-calloc.rs#llvm21: pass -> [missing] (J2)
[codegen] tests/codegen-llvm/vec-calloc.rs#normal: pass -> [missing] (J2)
[codegen] tests/codegen-llvm/enum/enum-discriminant-eq.rs: [missing] -> pass (J3)
[codegen] tests/codegen-llvm/enum/enum-discriminant-eq.rs#LLVM21: pass -> [missing] (J3)
[assembly] tests/assembly-llvm/nvptx-safe-naming.rs#LLVM20: ignore (ignored when the LLVM version (21.1.2) is newer than majorversion 20) -> [missing] (J5)
[codegen] tests/codegen-llvm/deduced-param-attrs.rs#LLVM20: ignore (ignored when the LLVM version (21.1.2) is newer than majorversion 20) -> [missing] (J5)
[codegen] tests/codegen-llvm/enum/enum-discriminant-eq.rs#LLVM20: ignore (ignored when the LLVM version (21.1.2) is newer than majorversion 20) -> [missing] (J5)
[ui] tests/ui/sanitizer/kcfi-arity-requires-llvm-21-0-0.rs: ignore (ignored when the LLVM version (21.1.2) is newer than majorversion 20) -> [missing] (J5)
[assembly] tests/assembly-llvm/nvptx-safe-naming.rs: [missing] -> ignore (only executed when the architecture is nvptx64) (J6)
[assembly] tests/assembly-llvm/nvptx-safe-naming.rs#LLVM21: ignore (only executed when the architecture is nvptx64) -> [missing] (J6)
[codegen] tests/codegen-llvm/deduced-param-attrs.rs: [missing] -> pass (J6)
[codegen] tests/codegen-llvm/deduced-param-attrs.rs#LLVM21: pass -> [missing] (J6)
[codegen] tests/codegen-llvm/option-niche-eq.rs: [missing] -> pass (J6)
[codegen] tests/codegen-llvm/option-niche-eq.rs#LLVM21: pass -> [missing] (J6)
[codegen] tests/codegen-llvm/option-niche-eq.rs#REGULAR: pass -> [missing] (J6)
[codegen] tests/codegen-llvm/vec-calloc.rs: [missing] -> ignore (only executed when the architecture is x86_64) (J8)
[codegen] tests/codegen-llvm/vec-calloc.rs#llvm21: ignore (only executed when the architecture is x86_64) -> [missing] (J8)
[codegen] tests/codegen-llvm/vec-calloc.rs#normal: ignore (only executed when the architecture is x86_64) -> [missing] (J8)
[codegen] tests/codegen-llvm/enum/enum-discriminant-eq.rs: [missing] -> ignore (only executed when the pointer width is 64bit) (J9)
[codegen] tests/codegen-llvm/enum/enum-discriminant-eq.rs#LLVM21: ignore (only executed when the pointer width is 64bit) -> [missing] (J9)
[ui] tests/ui/sanitizer/kcfi-arity-requires-llvm-21-0-0.rs: ignore (ignored when the LLVM version (22.1.0) is newer than majorversion 20) -> [missing] (J10)

Job group index

Test dashboard

Run

cargo run --manifest-path src/ci/citool/Cargo.toml -- \
    test-dashboard 8db65c71725664d85d06ec96ee3e575665de1f6a --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-aarch64-apple: 1h 39m -> 2h 10m (+31.8%)
dist-apple-various: 1h 23m -> 1h 48m (+29.6%)
aarch64-apple: 2h 26m -> 2h 54m (+19.0%)
dist-aarch64-msvc: 1h 51m -> 1h 31m (-18.1%)
dist-x86_64-apple: 2h 17m -> 1h 53m (-17.4%)
i686-gnu-2: 1h 42m -> 1h 25m (-16.9%)
x86_64-gnu-tools: 1h 1m -> 52m 13s (-14.8%)
pr-check-1: 32m 9s -> 27m 47s (-13.6%)
i686-gnu-nopt-1: 2h 15m -> 1h 57m (-13.4%)
armhf-gnu: 1h 32m -> 1h 20m (-13.0%)

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 · 2026-03-13T14:22:50Z

Finished benchmarking commit (8db65c7): comparison URL.

Overall result: ❌ regressions - 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)	1.1%	[1.1%, 1.1%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary 2.4%)

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

	mean	range	count
Regressions ❌ (primary)	2.4%	[2.4%, 2.4%]	2
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	2.4%	[2.4%, 2.4%]	2

Cycles

Results (primary 0.7%)

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

	mean	range	count
Regressions ❌ (primary)	3.5%	[3.5%, 3.5%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-2.1%	[-2.1%, -2.1%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.7%	[-2.1%, 3.5%]	2

Binary size

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

Bootstrap: 481.06s -> 481.871s (0.17%)
Artifact size: 395.03 MiB -> 397.07 MiB (0.51%)

rustbot assigned nikic Mar 11, 2026

nikic reviewed Mar 11, 2026

View reviewed changes

compiler/rustc_codegen_llvm/src/abi.rs Show resolved Hide resolved

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 Mar 11, 2026

cuviper added the relnotes Marks issues that should be documented in the release notes of the next release. label Mar 11, 2026

rustbot mentioned this pull request Mar 11, 2026

Tracking issue for release notes of #153684: Update the minimum external LLVM to 21 #153740

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rust-bors bot pushed a commit that referenced this pull request Mar 12, 2026

Auto merge of #153684 - cuviper:min-llvm-21, r=<try>

ab50e0e

Update the minimum external LLVM to 21 try-job: dist-aarch64-msvc

cuviper commented Mar 12, 2026

View reviewed changes

Update the minimum external LLVM to 21

52dfa94

cuviper force-pushed the min-llvm-21 branch from 6eeba5e to 52dfa94 Compare March 12, 2026 23:45

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rust-bors bot added merged-by-bors This PR was explicitly merged by bors. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Mar 13, 2026

rust-bors bot merged commit 8db65c7 into rust-lang:main Mar 13, 2026
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rustbot added this to the 1.96.0 milestone Mar 13, 2026

This was referenced Mar 13, 2026

add rustc option -Zpacked-stack #152432

Open

Fix LegacyKeyValueFormat report from docker build: x86_64-gnu #153372

Open

Actually enable the AIX Extended Altivec ABI in LLVM #153784

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cuviper deleted the min-llvm-21 branch March 13, 2026 14:02

cuviper mentioned this pull request Mar 13, 2026

Revamp cg_llvm debuginfo handling to use the LLVM-C API #134001

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Test differences

Stage 1

Stage 2

Job duration changes

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rust-timer commented Mar 13, 2026

Overall result: ❌ regressions - no action needed

Instruction count

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Cycles

Binary size

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