Don't walk into `Certainty::Yes` goals #142085

compiler-errors · 2025-06-05T15:05:18Z

Don't walk into Certainty::Yes goals in the pending obligation finding code, since they will not have been stalled on an infer var anyways

compiler-errors · 2025-06-05T15:05:28Z

@bors2 try @rust-timer queue

rust-bors · 2025-06-05T15:05:32Z

⌛ Trying commit 54b62fc with merge 3e60047…

To cancel the try build, run the command @bors2 try cancel.

[perf] test

rust-bors · 2025-06-05T17:37:29Z

☀️ Try build successful (CI)
Build commit: 3e60047 (3e60047b763a2a4010050b95bbae403458280cff)

rust-timer · 2025-06-05T19:45:04Z

Finished benchmarking commit (3e60047): comparison URL.

Overall result: ✅ improvements - no action needed

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.

@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
Regressions ❌ (secondary)	0.1%	[0.1%, 0.1%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-7.5%	[-16.2%, -0.8%]	6
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary 1.1%, 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)	4.3%	[4.3%, 4.3%]	1
Regressions ❌ (secondary)	3.1%	[3.1%, 3.1%]	1
Improvements ✅ (primary)	-2.1%	[-2.1%, -2.1%]	1
Improvements ✅ (secondary)	-2.1%	[-2.7%, -0.9%]	3
All ❌✅ (primary)	1.1%	[-2.1%, 4.3%]	2

Cycles

Results (secondary -12.8%)

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)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-12.8%	[-14.8%, -9.2%]	3
All ❌✅ (primary)	-	-	0

Binary size

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

Bootstrap: 750.544s -> 750.657s (0.02%)
Artifact size: 371.78 MiB -> 371.72 MiB (-0.02%)

compiler-errors · 2025-06-05T19:47:47Z

r? lcnr

rustbot · 2025-06-05T19:47:52Z

changes to inspect_obligations.rs

cc @compiler-errors, @lcnr

compiler-errors · 2025-06-05T19:56:01Z

compiler/rustc_hir_typeck/src/fn_ctxt/inspect_obligations.rs

+        // No need to walk into goal subtrees that certainly hold, since they
+        // wouldn't then be stalled on an infer var.
+        if inspect_goal.result() == Ok(Certainty::Yes)
+            && !matches!(


We currently report nested goals as Certainty::Yes even if they had nested goals... we could/should fix that?

normalizes-to goals?

in InspectGoal::new, we should also eagerly try to prove the nested goals if the normalizes_to_term_hack is Some 🤔

r=me with a FIXME here saying that normalizes-to nested goals are kinda scuffed or actually fix the impl in this PR

normalizes-to goals?

Yes, typo.

Fixed by #142127.

compiler-errors · 2025-06-06T17:14:34Z

@bors r=lcnr rollup=never

bors · 2025-06-06T17:14:36Z

📌 Commit db1ceca has been approved by lcnr

It is now in the queue for this repository.

bors · 2025-06-08T05:31:02Z

⌛ Testing commit db1ceca with merge 8072811...

bors · 2025-06-08T08:30:31Z

☀️ Test successful - checks-actions
Approved by: lcnr
Pushing 8072811 to master...

github-actions · 2025-06-08T08:33:34Z

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 0b65d0d (parent) -> 8072811 (this PR)

Test differences

No test diffs found

Test dashboard

Run

cargo run --manifest-path src/ci/citool/Cargo.toml -- \
    test-dashboard 8072811356a178dbdf8ca09b1635cfafd4661971 --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-apple-2: 4207.2s -> 3559.7s (-15.4%)
x86_64-rust-for-linux: 2872.0s -> 2506.7s (-12.7%)
dist-aarch64-apple: 5705.9s -> 5008.0s (-12.2%)
i686-gnu-2: 6054.2s -> 5321.1s (-12.1%)
arm-android: 5972.6s -> 5249.5s (-12.1%)
mingw-check-1: 1834.5s -> 1632.7s (-11.0%)
dist-apple-various: 7390.3s -> 6622.0s (-10.4%)
armhf-gnu: 4904.1s -> 4437.6s (-9.5%)
aarch64-apple: 4435.1s -> 4059.9s (-8.5%)
dist-arm-linux-gnueabi: 4712.0s -> 5082.3s (7.9%)

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 · 2025-06-08T09:57:53Z

Finished benchmarking commit (8072811): 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)	1.4%	[1.4%, 1.4%]	1
Regressions ❌ (secondary)	1.4%	[1.4%, 1.4%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-8.7%	[-17.9%, -0.8%]	6
All ❌✅ (primary)	1.4%	[1.4%, 1.4%]	1

Max RSS (memory usage)

Results (secondary -2.7%)

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)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.7%	[-3.3%, -2.1%]	3
All ❌✅ (primary)	-	-	0

Cycles

Results (primary 2.1%, secondary -8.4%)

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)	2.1%	[2.1%, 2.1%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-8.4%	[-17.1%, -3.9%]	8
All ❌✅ (primary)	2.1%	[2.1%, 2.1%]	1

Binary size

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

Bootstrap: 753.249s -> 752.812s (-0.06%)
Artifact size: 372.47 MiB -> 372.43 MiB (-0.01%)

panstromek · 2025-06-09T12:18:26Z

perf triage:

Syn regression is spurious, it's just returning to the default state in bimodal pattern.

Secondary regression is limited to new solver benchmark. New solver is not enabled by default, yet.

@rustbot label: +perf-regression-triaged

rustbot added the T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. label Jun 5, 2025

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rust-bors bot added a commit that referenced this pull request Jun 5, 2025

Auto merge of #142085 - compiler-errors:perf-self-obl, r=<try>

3e60047

[perf] test

rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Jun 5, 2025

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rustbot removed the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Jun 5, 2025

compiler-errors changed the title ~~[perf] test~~ Don't walk into Certainty::Yes goals Jun 5, 2025

rustbot assigned lcnr Jun 5, 2025

compiler-errors marked this pull request as ready for review June 5, 2025 19:47

rustbot added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jun 5, 2025

compiler-errors commented Jun 5, 2025

View reviewed changes

Don't walk into Certainty::Yes subgoals in NestedObligationsForSelfTy

db1ceca

compiler-errors force-pushed the perf-self-obl branch from 54b62fc to db1ceca Compare June 6, 2025 17:14

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 Jun 6, 2025

compiler-errors mentioned this pull request Jun 6, 2025

Apply nested goals certainty to InspectGoals for normalizes-to #142127

Open

bors added the merged-by-bors This PR was explicitly merged by bors. label Jun 8, 2025

bors merged commit 8072811 into rust-lang:master Jun 8, 2025
11 checks passed

rustbot added this to the 1.89.0 milestone Jun 8, 2025

rustbot added the perf-regression Performance regression. label Jun 8, 2025

rustbot added the perf-regression-triaged The performance regression has been triaged. label Jun 9, 2025

Don't walk into Certainty::Yes goals #142085

Don't walk into Certainty::Yes goals #142085

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rust-timer commented Jun 5, 2025

Overall result: ✅ improvements - no action needed

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compiler-errors commented Jun 5, 2025

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compiler-errors commented Jun 6, 2025

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bors commented Jun 6, 2025

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bors commented Jun 8, 2025

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github-actions bot commented Jun 8, 2025

Test differences

Job duration changes

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rust-timer commented Jun 8, 2025

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

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panstromek commented Jun 9, 2025

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Don't walk into `Certainty::Yes` goals #142085

Don't walk into `Certainty::Yes` goals #142085

compiler-errors commented Jun 5, 2025 •

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