Optimize region constraints #144446

nnethercote · 2025-07-25T12:44:19Z

r? @lcnr

nnethercote · 2025-07-27T22:59:07Z

@bors try @rust-timer queue

Optimize region constraints

rust-bors · 2025-07-27T22:59:11Z

⌛ Trying commit c7ec775 with merge eb4c1dc…

To cancel the try build, run the command @bors try cancel.

rust-bors · 2025-07-28T01:18:54Z

☀️ Try build successful (CI)
Build commit: eb4c1dc (eb4c1dc9331b928cb400f7da5ada2051b02ac7c5, parent: f8e355c230c6eb7b78ffce6a92fd81f78c890524)

rust-timer · 2025-07-28T04:44:35Z

Finished benchmarking commit (eb4c1dc): 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)	-	-	0
Regressions ❌ (secondary)	1.0%	[0.7%, 1.2%]	9
Improvements ✅ (primary)	-0.1%	[-0.2%, -0.1%]	5
Improvements ✅ (secondary)	-0.7%	[-1.0%, -0.3%]	18
All ❌✅ (primary)	-0.1%	[-0.2%, -0.1%]	5

Max RSS (memory usage)

Results (primary 2.4%, 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)	2.4%	[1.7%, 3.1%]	2
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-4.5%	[-4.5%, -4.5%]	1
All ❌✅ (primary)	2.4%	[1.7%, 3.1%]	2

Cycles

Results (primary -3.6%, secondary -5.3%)

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

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-3.6%	[-3.6%, -3.6%]	1
Improvements ✅ (secondary)	-5.3%	[-7.3%, -3.4%]	3
All ❌✅ (primary)	-3.6%	[-3.6%, -3.6%]	1

Binary size

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

Bootstrap: 465.942s -> 467.491s (0.33%)
Artifact size: 376.74 MiB -> 376.87 MiB (0.04%)

rustbot · 2025-07-30T22:29:51Z

Some changes occurred to the core trait solver

cc @rust-lang/initiative-trait-system-refactor

nnethercote · 2025-07-30T22:52:33Z

@bors try @rust-timer queue

rust-bors · 2025-07-30T22:52:37Z

⌛ Trying commit c7ec775 with merge 047aa5d…

To cancel the try build, run the command @bors try cancel.

Optimize region constraints

rust-bors · 2025-07-31T01:10:58Z

☀️ Try build successful (CI)
Build commit: 047aa5d (047aa5de0f87659075675f4173cfd968f0daeebc, parent: 3048886e59c94470e726ecaaf2add7242510ac11)

rust-timer · 2025-07-31T02:51:23Z

Finished benchmarking commit (047aa5d): comparison URL.

Overall result: ✅ improvements - no action needed

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.

@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)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.1%	[-0.1%, -0.1%]	5
Improvements ✅ (secondary)	-0.7%	[-1.1%, -0.1%]	19
All ❌✅ (primary)	-0.1%	[-0.1%, -0.1%]	5

Max RSS (memory usage)

Results (primary -0.3%, secondary 2.9%)

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

	mean	range	count
Regressions ❌ (primary)	1.8%	[1.3%, 2.7%]	3
Regressions ❌ (secondary)	2.9%	[2.9%, 2.9%]	1
Improvements ✅ (primary)	-2.3%	[-3.5%, -0.8%]	3
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-0.3%	[-3.5%, 2.7%]	6

Cycles

Results (secondary -2.3%)

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

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

Binary size

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

Bootstrap: 470.294s -> 469.489s (-0.17%)
Artifact size: 376.85 MiB -> 376.89 MiB (0.01%)

lcnr · 2025-07-31T09:32:06Z

compiler/rustc_infer/src/infer/lexical_region_resolve/mod.rs

-                    }
-                    VarValue::Value(a_region) => {
-                        let b_data = var_values.value_mut(b_vid);
+                        VarValue::Value(a_region) => {


Suggested change

VarValue::Value(a_region) => {

VarValue::Value(sub_region) => {

lcnr

nit, then r=me

If the two regions are the same, we can skip it. This is a small perf win.

This commit changes it to store a `Region` instead of a `RegionVid` for the `Var` cases: - We avoid having to call `Region::new_var` to re-create `Region`s from `RegionVid`s in a few places, avoiding the interning process, giving a small perf win. (At the cost of the type allowing some invalid combinations of values.) - All the cases now store two `Region`s, so the commit also separates the `ConstraintKind` (a new type) from the `sub` and `sup` arguments in `Constraint`.

nnethercote · 2025-07-31T10:11:12Z

I addressed the nit.

@bors r=lcnr

bors · 2025-07-31T10:11:16Z

📌 Commit 066a973 has been approved by lcnr

It is now in the queue for this repository.

Optimize region constraints r? `@lcnr`

bors · 2025-07-31T15:12:44Z

⌛ Testing commit 066a973 with merge ffb8b2f...

bors · 2025-07-31T16:41:12Z

💔 Test failed - checks-actions

nnethercote · 2025-07-31T22:05:56Z

Looks like some kind of network issue.

@bors retry

bors · 2025-08-01T04:06:24Z

⌛ Testing commit 066a973 with merge 6c02dd4...

bors · 2025-08-01T07:08:36Z

☀️ Test successful - checks-actions
Approved by: lcnr
Pushing 6c02dd4 to master...

github-actions · 2025-08-01T07:11:36Z

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 adcb3d3 (parent) -> 6c02dd4 (this PR)

Test differences

Show 1 test diff

1 doctest diff were found. These are ignored, as they are noisy.

Test dashboard

Run

cargo run --manifest-path src/ci/citool/Cargo.toml -- \
    test-dashboard 6c02dd4eae83befde07dc4782395e2005055e9fa --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

aarch64-apple: 4568.7s -> 6259.9s (37.0%)
x86_64-apple-2: 5867.8s -> 4262.9s (-27.4%)
dist-apple-various: 5496.8s -> 4528.8s (-17.6%)
dist-x86_64-freebsd: 4928.1s -> 5728.2s (16.2%)
x86_64-apple-1: 7959.0s -> 8791.6s (10.5%)
pr-check-1: 1695.4s -> 1862.3s (9.8%)
dist-aarch64-apple: 5187.9s -> 5594.5s (7.8%)
aarch64-gnu-llvm-19-1: 3930.2s -> 3630.5s (-7.6%)
dist-sparcv9-solaris: 5437.9s -> 5060.4s (-6.9%)
x86_64-gnu-tools: 4004.7s -> 3729.7s (-6.9%)

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 · 2025-08-01T08:19:51Z

Finished benchmarking commit (6c02dd4): 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)	-0.1%	[-0.1%, -0.1%]	2
Improvements ✅ (secondary)	-0.5%	[-1.0%, -0.3%]	12
All ❌✅ (primary)	-0.1%	[-0.1%, -0.1%]	2

Max RSS (memory usage)

Results (primary 0.9%, secondary 2.5%)

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

	mean	range	count
Regressions ❌ (primary)	2.9%	[1.4%, 4.5%]	2
Regressions ❌ (secondary)	2.5%	[2.5%, 2.5%]	1
Improvements ✅ (primary)	-3.0%	[-3.0%, -3.0%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.9%	[-3.0%, 4.5%]	3

Cycles

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

Binary size

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

Bootstrap: 468.61s -> 467.393s (-0.26%)
Artifact size: 376.82 MiB -> 376.76 MiB (-0.02%)

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rust-bors bot added a commit that referenced this pull request Jul 27, 2025

Auto merge of #144446 - nnethercote:opt-region-constraints, r=<try>

eb4c1dc

Optimize region constraints

rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Jul 27, 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 Jul 28, 2025

nnethercote marked this pull request as ready for review July 30, 2025 22:29

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jul 30, 2025

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rust-bors bot added a commit that referenced this pull request Jul 30, 2025

Auto merge of #144446 - nnethercote:opt-region-constraints, r=<try>

047aa5d

Optimize region constraints

rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Jul 30, 2025

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rustbot removed S-waiting-on-perf Status: Waiting on a perf run to be completed. perf-regression Performance regression. labels Jul 31, 2025

rustbot assigned lcnr Jul 31, 2025

lcnr reviewed Jul 31, 2025

View reviewed changes

nnethercote added 2 commits July 31, 2025 20:04

Avoid vacuous Constraint::{VarSubVar,RegSubReg} constraints.

75a1f47

If the two regions are the same, we can skip it. This is a small perf win.

nnethercote force-pushed the opt-region-constraints branch from c7ec775 to 066a973 Compare July 31, 2025 10:10

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 Jul 31, 2025

bors added a commit that referenced this pull request Jul 31, 2025

Auto merge of #144446 - nnethercote:opt-region-constraints, r=lcnr

ffb8b2f

Optimize region constraints r? `@lcnr`

bors added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Jul 31, 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 Jul 31, 2025

bors added the merged-by-bors This PR was explicitly merged by bors. label Aug 1, 2025

bors merged commit 6c02dd4 into rust-lang:master Aug 1, 2025
11 checks passed

rustbot added this to the 1.90.0 milestone Aug 1, 2025

	VarValue::Value(a_region) => {
	VarValue::Value(sub_region) => {

Optimize region constraints #144446

Optimize region constraints #144446

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nnethercote commented Jul 25, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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rust-timer commented Jul 28, 2025

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

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rust-timer commented Jul 31, 2025

Overall result: ✅ improvements - no action needed

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nnethercote commented Jul 31, 2025

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Test differences

Job duration changes

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rust-timer commented Aug 1, 2025

Overall result: ✅ improvements - no action needed

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nnethercote commented Jul 25, 2025 •

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