Allow GVN to produce places and not just locals. #139327

cjgillot · 2025-04-03T14:51:40Z

That may be too big of a hammer, as we may introduce new deref projections (possible UB footgun + probably not good for perf).

The second commit opts out of introducing projections that don't have a stable offset, which is probably what we want. Hence no new Deref and no new Index projections.

Fixes #138936
cc @scottmcm @dianqk

rustbot · 2025-04-03T14:51:45Z

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

cjgillot · 2025-04-03T15:41:03Z

@bors try @rust-timer queue

Allow GVN to produce places and not just locals. That may be too big of a hammer, as we may introduce new deref projections (possible UB footgun + probably not good for perf). r? `@ghost` for perf Fixes rust-lang#138936 cc `@scottmcm` `@dianqk`

bors · 2025-04-03T15:42:15Z

⌛ Trying commit 731a3e6 with merge 277319f...

bors · 2025-04-03T17:49:20Z

☀️ Try build successful - checks-actions
Build commit: 277319f (277319f2de9573bbed55fea209bcdaca385a235c)

rust-timer · 2025-04-04T00:55:53Z

Finished benchmarking commit (277319f): comparison URL.

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

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. While you can manually mark this PR as fit for rollup, we strongly recommend not doing so since this PR may lead to changes in compiler perf.

Next Steps: If you can justify the regressions found in this try perf run, please indicate this with @rustbot label: +perf-regression-triaged along with sufficient written justification. If you cannot justify the regressions please fix the regressions and do another perf run. If the next run shows neutral or positive results, the label will be automatically removed.

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

Instruction count

This is the most reliable metric that we have; it was used to determine the overall result at the top of this comment. However, even this metric can sometimes exhibit noise.

	mean	range	count
Regressions ❌ (primary)	0.6%	[0.5%, 0.7%]	2
Regressions ❌ (secondary)	0.5%	[0.1%, 1.1%]	22
Improvements ✅ (primary)	-0.4%	[-0.9%, -0.2%]	7
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-0.2%	[-0.9%, 0.7%]	9

Max RSS (memory usage)

Results (primary 0.2%, secondary -0.8%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	2.0%	[1.5%, 2.3%]	3
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-2.5%	[-2.8%, -2.2%]	2
Improvements ✅ (secondary)	-0.8%	[-0.8%, -0.8%]	1
All ❌✅ (primary)	0.2%	[-2.8%, 2.3%]	5

Cycles

Results (primary 0.9%, secondary 2.3%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	0.9%	[0.9%, 0.9%]	1
Regressions ❌ (secondary)	2.3%	[2.2%, 2.5%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.9%	[0.9%, 0.9%]	1

Binary size

Results (primary -0.1%, secondary 0.0%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	0.2%	[0.0%, 0.5%]	13
Regressions ❌ (secondary)	0.2%	[0.2%, 0.4%]	39
Improvements ✅ (primary)	-0.2%	[-0.4%, -0.0%]	41
Improvements ✅ (secondary)	-0.8%	[-1.4%, -0.3%]	9
All ❌✅ (primary)	-0.1%	[-0.4%, 0.5%]	54

Bootstrap: 776.226s -> 778.039s (0.23%)
Artifact size: 365.90 MiB -> 365.88 MiB (-0.01%)

cjgillot · 2025-04-04T11:28:10Z

@bors try @rust-timer queue

Allow GVN to produce places and not just locals. That may be too big of a hammer, as we may introduce new deref projections (possible UB footgun + probably not good for perf). r? `@ghost` for perf Fixes rust-lang#138936 cc `@scottmcm` `@dianqk`

bors · 2025-04-04T11:29:21Z

⌛ Trying commit d9caf84 with merge 631e9e6...

bors · 2025-04-04T13:40:59Z

☀️ Try build successful - checks-actions
Build commit: 631e9e6 (631e9e60f5e36e847dd5dc1d5813c4a0f6960401)

rust-timer · 2025-04-04T19:27:22Z

Finished benchmarking commit (631e9e6): comparison URL.

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

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. While you can manually mark this PR as fit for rollup, we strongly recommend not doing so since this PR may lead to changes in compiler perf.

Next Steps: If you can justify the regressions found in this try perf run, please indicate this with @rustbot label: +perf-regression-triaged along with sufficient written justification. If you cannot justify the regressions please fix the regressions and do another perf run. If the next run shows neutral or positive results, the label will be automatically removed.

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

Instruction count

This is the most reliable metric that we have; it was used to determine the overall result at the top of this comment. However, even this metric can sometimes exhibit noise.

	mean	range	count
Regressions ❌ (primary)	0.5%	[0.5%, 0.5%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.6%	[-0.6%, -0.6%]	1
Improvements ✅ (secondary)	-0.8%	[-0.9%, -0.2%]	7
All ❌✅ (primary)	-0.0%	[-0.6%, 0.5%]	2

Max RSS (memory usage)

Results (primary -1.3%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	3.7%	[3.5%, 3.8%]	2
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-3.9%	[-6.1%, -2.8%]	4
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-1.3%	[-6.1%, 3.8%]	6

Cycles

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

Binary size

Results (primary 0.0%, secondary 0.0%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	0.2%	[0.0%, 1.5%]	19
Regressions ❌ (secondary)	0.0%	[0.0%, 0.0%]	4
Improvements ✅ (primary)	-0.3%	[-0.6%, -0.0%]	11
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.0%	[-0.6%, 1.5%]	30

Bootstrap: 778.988s -> 778.401s (-0.08%)
Artifact size: 365.99 MiB -> 365.96 MiB (-0.01%)

cjgillot · 2025-04-04T20:56:32Z

r? compiler

oli-obk · 2025-04-08T16:08:03Z

@bors r+

bors · 2025-04-08T16:08:07Z

📌 Commit d9caf84 has been approved by oli-obk

It is now in the queue for this repository.

jieyouxu · 2025-04-08T23:05:47Z

@bors p=5 (rollup threading)

bors · 2025-04-09T08:50:41Z

⌛ Testing commit d9caf84 with merge f06e5c1...

bors · 2025-04-09T12:02:13Z

☀️ Test successful - checks-actions
Approved by: oli-obk
Pushing f06e5c1 to master...

github-actions · 2025-04-09T12:04:00Z

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 97c966b (parent) -> f06e5c1 (this PR)

Test differences

Show 2 test diffs

Stage 1

[mir-opt] tests/mir-opt/gvn_copy_constant_projection.rs: [missing] -> pass (J1)

Stage 2

[mir-opt] tests/mir-opt/gvn_copy_constant_projection.rs: [missing] -> pass (J0)

Job group index

J0: aarch64-apple, aarch64-gnu, arm-android, armhf-gnu, dist-i586-gnu-i586-i686-musl, i686-gnu-1, i686-gnu-nopt-1, i686-msvc-1, test-various, x86_64-apple-1, x86_64-gnu, x86_64-gnu-llvm-19-1, x86_64-gnu-llvm-19-2, x86_64-gnu-nopt, x86_64-gnu-stable, x86_64-mingw-1, x86_64-msvc-1
J1: x86_64-gnu-llvm-19-3

Job duration changes

aarch64-apple: 3676.7s -> 4495.6s (22.3%)
dist-aarch64-apple: 4402.7s -> 5203.3s (18.2%)
x86_64-apple-2: 4755.2s -> 5237.7s (10.1%)
dist-apple-various: 5396.1s -> 5902.4s (9.4%)
x86_64-gnu-stable: 6626.8s -> 6957.6s (5.0%)
dist-x86_64-msvc: 5950.4s -> 6168.4s (3.7%)
dist-x86_64-linux: 5463.5s -> 5633.8s (3.1%)
x86_64-gnu: 6397.4s -> 6593.4s (3.1%)
x86_64-gnu-nopt: 5564.0s -> 5728.7s (3.0%)
dist-x86_64-illumos: 5667.0s -> 5816.0s (2.6%)

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.

rust-timer · 2025-04-09T13:18:26Z

Finished benchmarking commit (f06e5c1): comparison URL.

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

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

This is the most reliable metric that we have; it was used to determine the overall result at the top of this comment. However, even this metric can sometimes exhibit noise.

	mean	range	count
Regressions ❌ (primary)	0.7%	[0.7%, 0.7%]	1
Regressions ❌ (secondary)	0.7%	[0.7%, 0.7%]	1
Improvements ✅ (primary)	-0.6%	[-0.6%, -0.6%]	1
Improvements ✅ (secondary)	-0.6%	[-0.9%, -0.2%]	10
All ❌✅ (primary)	0.0%	[-0.6%, 0.7%]	2

Max RSS (memory usage)

Results (primary 5.0%, secondary 1.7%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	6.6%	[4.0%, 8.8%]	5
Regressions ❌ (secondary)	6.6%	[6.6%, 6.6%]	1
Improvements ✅ (primary)	-2.9%	[-2.9%, -2.9%]	1
Improvements ✅ (secondary)	-3.2%	[-3.2%, -3.2%]	1
All ❌✅ (primary)	5.0%	[-2.9%, 8.8%]	6

Cycles

Results (secondary 2.8%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	2.8%	[2.8%, 2.8%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Binary size

Results (primary -0.0%, secondary 0.0%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	0.2%	[0.0%, 1.5%]	15
Regressions ❌ (secondary)	0.0%	[0.0%, 0.0%]	2
Improvements ✅ (primary)	-0.2%	[-0.5%, -0.0%]	15
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-0.0%	[-0.5%, 1.5%]	30

Bootstrap: 778.182s -> 779.721s (0.20%)
Artifact size: 366.15 MiB -> 366.13 MiB (-0.01%)

Mark-Simulacrum · 2025-04-14T12:13:48Z

Regressions look plausibly real, but are limited (~2 scenarios) and outweighed by benefits. Marking as 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 3, 2025

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rustbot added perf-regression Performance regression. and removed S-waiting-on-perf Status: Waiting on a perf run to be completed. labels Apr 4, 2025

cjgillot added 2 commits April 4, 2025 10:55

Allow GVN to produce places and not just locals.

109edab

Only introduce stable projections.

d9caf84

cjgillot force-pushed the gvn-place branch from 731a3e6 to d9caf84 Compare April 4, 2025 10:59

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rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Apr 4, 2025

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rustbot removed the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Apr 4, 2025

rustbot assigned oli-obk Apr 4, 2025

bors 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 8, 2025

bors added the merged-by-bors This PR was explicitly merged by bors. label Apr 9, 2025

bors merged commit f06e5c1 into rust-lang:master Apr 9, 2025
7 checks passed

rustbot added this to the 1.88.0 milestone Apr 9, 2025

cjgillot deleted the gvn-place branch April 10, 2025 23:18

Mark-Simulacrum added the perf-regression-triaged The performance regression has been triaged. label Apr 14, 2025

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Allow GVN to produce places and not just locals. #139327

Allow GVN to produce places and not just locals. #139327

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Allow GVN to produce places and not just locals. #139327

Allow GVN to produce places and not just locals. #139327

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

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

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Test differences

Stage 1

Stage 2

Job duration changes

rust-timer commented Apr 9, 2025

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

Mark-Simulacrum commented Apr 14, 2025

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