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Disable incr CGU merging#146146

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saethlin:disable-incr-merging
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Disable incr CGU merging#146146
saethlin wants to merge 1 commit intorust-lang:mainfrom
saethlin:disable-incr-merging

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@saethlin saethlin commented Sep 3, 2025

For perf comparison in #145910

@rustbot rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Sep 3, 2025
@saethlin saethlin added the S-experimental Status: Ongoing experiment that does not require reviewing and won't be merged in its current state. label Sep 3, 2025
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saethlin commented Sep 3, 2025

@bors try @rust-timer queue

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rust-bors Bot added a commit that referenced this pull request Sep 3, 2025
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Auto merge of #146146 - saethlin:disable-incr-merging, r=<try>
7cb1a81 
Disable incr CGU merging
@rustbot rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Sep 3, 2025
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rust-bors Bot commented Sep 3, 2025

☀️ Try build successful (CI)
Build commit: 7cb1a81 (7cb1a81145a739c4fd858abe3c624ce8e6e5f9cd, parent: 51ff895062ba60a7cba53f57af928c3fb7b0f2f4)

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rust-timer commented Sep 3, 2025

Finished benchmarking commit (7cb1a81): comparison URL.

Overall result: ❌✅ regressions and improvements - please read the text below

Benchmarking this pull request means it may be perf-sensitive – we'll automatically label it not fit for rolling up. You can override this, but we strongly advise not to, due to possible changes in compiler perf.

Next Steps: If you can justify the regressions found in this try perf run, please do so in sufficient writing along with @rustbot label: +perf-regression-triaged. If not, please fix the regressions and do another perf run. If its results are neutral or positive, the label will be automatically removed.

@bors rollup=never
@rustbot label: -S-waiting-on-perf +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)		 1.3% [0.4%, 4.0%] 16
Regressions ❌
(secondary)		 19.0% [0.1%, 59.8%] 8
Improvements ✅
(primary)		 -13.3% [-84.8%, -0.1%] 8
Improvements ✅
(secondary)		 - - 0
All ❌✅ (primary) -3.6% [-84.8%, 4.0%] 24

Max RSS (memory usage)

Results (primary -2.9%, secondary 2.6%)

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

mean range count
Regressions ❌
(primary)		 7.0% [7.0%, 7.0%] 1
Regressions ❌
(secondary)		 2.6% [2.1%, 3.1%] 5
Improvements ✅
(primary)		 -12.8% [-12.8%, -12.8%] 1
Improvements ✅
(secondary)		 - - 0
All ❌✅ (primary) -2.9% [-12.8%, 7.0%] 2

Cycles

Results (primary -7.7%, secondary 16.3%)

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

mean range count
Regressions ❌
(primary)		 2.8% [2.2%, 4.1%] 5
Regressions ❌
(secondary)		 22.6% [5.0%, 48.4%] 6
Improvements ✅
(primary)		 -16.4% [-84.4%, -1.8%] 6
Improvements ✅
(secondary)		 -2.4% [-2.8%, -2.0%] 2
All ❌✅ (primary) -7.7% [-84.4%, 4.1%] 11

Binary size

Results (primary 2.9%, secondary 3.8%)

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

mean range count
Regressions ❌
(primary)		 2.9% [0.0%, 16.0%] 33
Regressions ❌
(secondary)		 3.8% [3.7%, 3.9%] 6
Improvements ✅
(primary)		 - - 0
Improvements ✅
(secondary)		 - - 0
All ❌✅ (primary) 2.9% [0.0%, 16.0%] 33

Bootstrap: 465.874s -> 465.493s (-0.08%)
Artifact size: 388.34 MiB -> 388.38 MiB (0.01%)

@rustbot rustbot added perf-regression Performance regression. and removed S-waiting-on-perf Status: Waiting on a perf run to be completed. labels Sep 3, 2025
@saethlin saethlin force-pushed the disable-incr-merging branch from 7502ea2 to 9366061 Compare October 6, 2025 00:37
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rust-log-analyzer commented Oct 6, 2025

The job aarch64-gnu-llvm-20-1 failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot) 
test [codegen-units] tests/codegen-units/item-collection/unreferenced-const-fn.rs ... ok
test [codegen-units] tests/codegen-units/item-collection/unreferenced-inline-function.rs ... ok
test [codegen-units] tests/codegen-units/item-collection/unused-traits-and-generics.rs ... ok
test [codegen-units] tests/codegen-units/item-collection/unsizing.rs ... ok
FATAL: !(missing.is_empty() && unexpected.is_empty() && wrong_cgus.is_empty())
test [codegen-units] tests/codegen-units/partitioning/incremental-merging.rs ... FAILED
test [codegen-units] tests/codegen-units/partitioning/inline-always.rs ... ok
test [codegen-units] tests/codegen-units/partitioning/extern-generic.rs ... ok
test [codegen-units] tests/codegen-units/partitioning/extern-drop-glue.rs ... ok
test [codegen-units] tests/codegen-units/partitioning/local-drop-glue.rs ... ok
---
---- [codegen-units] tests/codegen-units/partitioning/incremental-merging.rs stdout ----

The following items were assigned to wrong codegen units:

fn aaa::foo
  expected: incremental_merging-aaa--incremental_merging-bbb[External] 
  actual:   incremental_merging-aaa[External] 

fn bbb::foo
  expected: incremental_merging-aaa--incremental_merging-bbb[External] 
  actual:   incremental_merging-bbb[External] 


thread '[codegen-units] tests/codegen-units/partitioning/incremental-merging.rs' panicked at src/tools/compiletest/src/runtest/codegen_units.rs:111:13:
fatal error
stack backtrace:

@Dylan-DPC Dylan-DPC removed the S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. label Apr 29, 2026
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