Fix performance regression introduced in #142531 by excluding `Storage{Live,Dead}` from CGU size estimation by ohadravid · Pull Request #155491 · rust-lang/rust

ohadravid · 2026-04-18T16:41:16Z

Fix performance regression introduced in #142531 (rust-timer comment) by excluding Storage{Live,Dead} from CGU size estimation.

Also, avoid unneeded work for storage removal in non-opt builds in CopyProp and GVN
by allocating local sets for the storage accounting only when tcx.sess.emit_lifetime_markers().

r? saethlin

rustbot · 2026-04-18T16:41:20Z

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

ohadravid · 2026-04-18T19:09:39Z

        for (local, &head) in ssa.copy_classes().iter_enumerated() {
            if local != head {
                any_replacement = true;
-                storage_to_remove.insert(head);


Before, Replacer used unified to check which locals require storage removal - so this is fine
https://github.com/rust-lang/rust/pull/142531/changes#diff-0004c9822ecc282c9d6f6bcec22d1b50d49c6165e8093c1dbd2607086278dc19L96

View changes since the review

… and GVN

Kobzol · 2026-04-18T20:49:12Z

@bors try @rust-timer queue

… r=<try> Avoid unneeded work for storage removal in non-opt builds in CopyProp and GVN

rust-bors · 2026-04-18T22:59:37Z

☀️ Try build successful (CI)
Build commit: 48af6e0 (48af6e0fab57d8f8b2679fe3401c5b490589dad7, parent: b2f1ccf524a3a4cf9c34545167cc23b659cf1cbd)

rust-timer · 2026-04-18T23:46:32Z

Finished benchmarking commit (48af6e0): comparison URL.

Overall result: no relevant changes - no action needed

Benchmarking means the PR may be perf-sensitive. It's automatically marked not fit for rolling up. Overriding is possible but disadvised: it risks changing compiler perf.

@bors rollup=never
@rustbot label: -S-waiting-on-perf -perf-regression

Instruction count

This perf run didn't have relevant results for this metric.

Max RSS (memory usage)

Results (primary 4.2%, secondary -1.5%)

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

	mean	range	count
Regressions ❌ (primary)	4.2%	[3.0%, 5.4%]	2
Regressions ❌ (secondary)	1.2%	[1.2%, 1.2%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-4.2%	[-4.2%, -4.2%]	1
All ❌✅ (primary)	4.2%	[3.0%, 5.4%]	2

Cycles

Results (primary 2.6%, secondary 6.2%)

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

	mean	range	count
Regressions ❌ (primary)	2.6%	[2.6%, 2.6%]	1
Regressions ❌ (secondary)	6.2%	[3.8%, 8.5%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	2.6%	[2.6%, 2.6%]	1

Binary size

This perf run didn't have relevant results for this metric.

Bootstrap: 492.524s -> 492.577s (0.01%)
Artifact size: 394.41 MiB -> 394.45 MiB (0.01%)

ohadravid · 2026-04-19T08:06:27Z

(I probably won't be able to do this, right @Kobzol ?)

@bors try @rust-timer queue

rust-bors · 2026-04-19T08:06:30Z

@ohadravid: 🔑 Insufficient privileges: not in try users

panstromek · 2026-04-19T08:31:52Z

@bors try @rust-timer queue

… r=<try> Avoid unneeded work for storage removal in non-opt builds in CopyProp and GVN

rust-bors · 2026-04-19T10:44:12Z

☀️ Try build successful (CI)
Build commit: 9ab524a (9ab524a53632bd338dd70682bc997e2503f70f8a, parent: ec2d669db8e5ca2cb1604c69a831ef244ebd9aa9)

rust-timer · 2026-04-19T11:24:32Z

Finished benchmarking commit (9ab524a): comparison URL.

Overall result: ❌✅ regressions and improvements - please read:

Benchmarking means the PR may be perf-sensitive. It's automatically marked not fit for rolling up. Overriding is possible but disadvised: it risks changing compiler perf.

Next, please: If you can, justify the regressions found in this try perf run in writing along with @rustbot label: +perf-regression-triaged. If not, fix the regressions and do another perf run. Neutral or positive results will clear the label automatically.

@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)	2.2%	[0.8%, 4.6%]	5
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-4.1%	[-14.1%, -0.2%]	9
Improvements ✅ (secondary)	-3.8%	[-9.1%, -1.1%]	3
All ❌✅ (primary)	-1.9%	[-14.1%, 4.6%]	14

Max RSS (memory usage)

Results (primary -1.7%, secondary -1.4%)

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

	mean	range	count
Regressions ❌ (primary)	2.6%	[2.1%, 2.9%]	3
Regressions ❌ (secondary)	4.6%	[4.6%, 4.6%]	1
Improvements ✅ (primary)	-3.3%	[-4.6%, -1.0%]	8
Improvements ✅ (secondary)	-3.3%	[-4.3%, -2.4%]	3
All ❌✅ (primary)	-1.7%	[-4.6%, 2.9%]	11

Cycles

Results (primary -3.4%, secondary -4.5%)

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

	mean	range	count
Regressions ❌ (primary)	3.8%	[2.2%, 5.6%]	3
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-8.9%	[-12.4%, -3.0%]	4
Improvements ✅ (secondary)	-4.5%	[-9.8%, -1.6%]	3
All ❌✅ (primary)	-3.4%	[-12.4%, 5.6%]	7

Binary size

Results (primary -0.2%, secondary -0.8%)

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

	mean	range	count
Regressions ❌ (primary)	0.7%	[0.2%, 2.0%]	11
Regressions ❌ (secondary)	1.1%	[1.1%, 1.1%]	1
Improvements ✅ (primary)	-0.7%	[-1.8%, -0.1%]	19
Improvements ✅ (secondary)	-1.0%	[-3.8%, -0.1%]	10
All ❌✅ (primary)	-0.2%	[-1.8%, 2.0%]	30

Bootstrap: 490.129s -> 492.074s (0.40%)
Artifact size: 394.32 MiB -> 394.29 MiB (-0.01%)

saethlin · 2026-04-20T02:40:22Z

Can you update the PR description to include the second commit as well? Then r=me. It's up to you if you want to include the initial optimization as well, I think it makes logical sense and doesn't introduce too much complexity so it would be okay to include it. Even though it doesn't seem very impactful.

ohadravid · 2026-04-20T04:22:17Z

@saethlin done 🙏

saethlin · 2026-04-21T00:49:37Z

@bors r+

rust-bors · 2026-04-21T00:49:40Z

📌 Commit 846974e has been approved by saethlin

It is now in the queue for this repository.

rust-bors · 2026-04-21T08:58:40Z

☀️ Test successful - CI
Approved by: saethlin
Duration: 3h 23m 16s
Pushing 9ab01ae to main...

github-actions · 2026-04-21T09:01:28Z

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 84c1190 (parent) -> 9ab01ae (this PR)

Test differences

Show 3 test diffs

3 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 9ab01ae53c416f89fe256b79588a76dcbcdc9290 --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

x86_64-msvc-2: 1h 58m -> 2h 38m (+34.2%)
x86_64-gnu-stable: 1h 50m -> 2h 19m (+26.0%)
dist-ohos-aarch64: 1h 3m -> 1h 17m (+21.7%)
aarch64-apple: 2h 42m -> 3h 17m (+21.4%)
dist-apple-various: 1h 25m -> 1h 42m (+20.3%)
dist-powerpc64-linux-musl: 1h 14m -> 1h 28m (+18.3%)
dist-android: 27m 55s -> 23m 11s (-16.9%)
dist-x86_64-apple: 2h -> 2h 19m (+16.2%)
x86_64-rust-for-linux: 55m 2s -> 46m 16s (-15.9%)
pr-check-1: 33m 5s -> 27m 52s (-15.8%)

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 · 2026-04-21T09:40:03Z

Finished benchmarking commit (9ab01ae): comparison URL.

Overall result: ❌✅ regressions and improvements - please read:

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)	2.1%	[0.8%, 4.6%]	5
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-4.2%	[-14.1%, -0.2%]	9
Improvements ✅ (secondary)	-3.9%	[-9.2%, -1.2%]	3
All ❌✅ (primary)	-1.9%	[-14.1%, 4.6%]	14

Max RSS (memory usage)

Results (primary -1.4%, secondary 0.0%)

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

	mean	range	count
Regressions ❌ (primary)	3.3%	[2.4%, 4.8%]	3
Regressions ❌ (secondary)	4.2%	[3.6%, 4.7%]	2
Improvements ✅ (primary)	-3.4%	[-5.9%, -0.9%]	7
Improvements ✅ (secondary)	-2.8%	[-3.9%, -1.1%]	3
All ❌✅ (primary)	-1.4%	[-5.9%, 4.8%]	10

Cycles

Results (primary -4.6%, secondary -4.1%)

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

	mean	range	count
Regressions ❌ (primary)	4.4%	[3.5%, 5.4%]	2
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-9.0%	[-13.0%, -3.5%]	4
Improvements ✅ (secondary)	-4.1%	[-9.2%, -2.2%]	9
All ❌✅ (primary)	-4.6%	[-13.0%, 5.4%]	6

Binary size

Results (primary -0.2%, secondary -0.7%)

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

	mean	range	count
Regressions ❌ (primary)	0.6%	[0.1%, 2.0%]	14
Regressions ❌ (secondary)	1.1%	[1.1%, 1.1%]	1
Improvements ✅ (primary)	-0.7%	[-2.2%, -0.1%]	22
Improvements ✅ (secondary)	-0.8%	[-3.8%, -0.1%]	14
All ❌✅ (primary)	-0.2%	[-2.2%, 2.0%]	36

Bootstrap: 490.276s -> 490.352s (0.02%)
Artifact size: 394.36 MiB -> 394.40 MiB (0.01%)

Kobzol · 2026-04-21T17:46:18Z

Fixed a previous regression from #142531.

@rustbot label: +perf-regression-triaged

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Apr 18, 2026

rustbot assigned saethlin Apr 18, 2026

ohadravid force-pushed the faster-storage-in-copyprop-and-gvn branch from 544ea18 to bb8798b Compare April 18, 2026 16:43

ohadravid commented Apr 18, 2026

View reviewed changes

Avoid unneeded work for storage removal in non-opt builds in CopyProp…

2389a3a

… and GVN

ohadravid force-pushed the faster-storage-in-copyprop-and-gvn branch from bb8798b to 2389a3a Compare April 18, 2026 19:13

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rust-bors Bot pushed a commit that referenced this pull request Apr 18, 2026

Auto merge of #155491 - ohadravid:faster-storage-in-copyprop-and-gvn,…

48af6e0

… r=<try> Avoid unneeded work for storage removal in non-opt builds in CopyProp and GVN

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rustbot removed the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Apr 18, 2026

Don't count storage statements in size_estimate query

846974e

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rust-bors Bot pushed a commit that referenced this pull request Apr 19, 2026

Auto merge of #155491 - ohadravid:faster-storage-in-copyprop-and-gvn,…

9ab524a

… r=<try> Avoid unneeded work for storage removal in non-opt builds in CopyProp and GVN

rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Apr 19, 2026

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rustbot added the perf-regression Performance regression. label Apr 19, 2026

rustbot removed the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Apr 19, 2026

ohadravid mentioned this pull request Apr 19, 2026

Remove fewer Storage calls in CopyProp and GVN #142531

Merged

ohadravid changed the title ~~Avoid unneeded work for storage removal in non-opt builds in CopyProp and GVN~~ Fix performance regression introduced in rust-lang/rust#142531 by excluding Storage{Live,Dead} from CGU size estimation Apr 20, 2026

ohadravid changed the title ~~Fix performance regression introduced in rust-lang/rust#142531 by excluding Storage{Live,Dead} from CGU size estimation~~ Fix performance regression introduced in #142531 by excluding Storage{Live,Dead} from CGU size estimation Apr 20, 2026

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 Apr 21, 2026

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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 Apr 21, 2026

rust-bors Bot merged commit 9ab01ae into rust-lang:main Apr 21, 2026
13 checks passed

rustbot added this to the 1.97.0 milestone Apr 21, 2026

rustbot added the perf-regression-triaged The performance regression has been triaged. label Apr 21, 2026

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rust-timer commented Apr 18, 2026

Overall result: no relevant changes - no action needed

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Overall result: ❌✅ regressions and improvements - please read:

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Test differences

Job duration changes

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rust-timer commented Apr 21, 2026

Overall result: ❌✅ regressions and improvements - please read:

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