Use Set instead of Vec in transitive_relation

[Noratrieb]

Helps with #103195. It doesn't fix the underlying quadraticness but it makes it a lot faster to an extent where even doubling the amount of nested references still takes less than two seconds (50s on nightly).

I want to see whether this causes regressions (because the vec was usually quite small) or improvements (as lookup for bigger sets is now much faster) in real code.

[rust-highfive]

r? @petrochenkov

(rust-highfive has picked a reviewer for you, use r? to override)

[thomcc]

@bors try @rust-timer queue

[rust-timer]

Awaiting bors try build completion.

@rustbot label: +S-waiting-on-perf

[bors]

⌛ Trying commit 04ab19fbde3eb5cc061ff6b026cc1b542d0c400d with merge cfee159701a9bf8017cebf2b31f22fae454b0c54...

[bors]

☀️ Try build successful - checks-actions
Build commit: cfee159701a9bf8017cebf2b31f22fae454b0c54 (cfee159701a9bf8017cebf2b31f22fae454b0c54)

[rust-timer]

Queued cfee159701a9bf8017cebf2b31f22fae454b0c54 with parent a24a020, future comparison URL.

[rust-timer]

Finished benchmarking commit (cfee159701a9bf8017cebf2b31f22fae454b0c54): 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-review -S-waiting-on-perf -perf-regression

Instruction count

This is a highly reliable metric that was used to determine the overall result at the top of this comment.

	mean1	range	count2
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.6%	[-0.7%, -0.5%]	2
Improvements ✅ (secondary)	-1.2%	[-1.6%, -0.6%]	7
All ❌✅ (primary)	-0.6%	[-0.7%, -0.5%]	2

Max RSS (memory usage)

Results

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.

	mean1	range	count2
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	3.4%	[2.0%, 5.3%]	10
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Cycles

Results

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.

	mean1	range	count2
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.9%	[-2.9%, -2.9%]	1
All ❌✅ (primary)	-	-	0

Footnotes

1. the arithmetic mean of the percent change ↩ ↩² ↩³

2. number of relevant changes ↩ ↩² ↩³

[est31]

Tbh the freeze function also looks pretty inefficient. A proper BFS would be better I think. Edit: you'd have to watch out for cycles, but there are ways to do that I think. Or can we assume cycle freedom?

[petrochenkov]

This is a perf improvement so r=me unless you want to address other comments like #103214 (comment).
@rustbot author

[Noratrieb]

The potential perf improvement for freeze sounds interesting, but I don't want to do this in this PR since it requires some more investigation. I'd prefer to land it as-is.
@rustbot ready

[Dylan-DPC]

@bors r=petrochenkov

[bors]

📌 Commit d45f025 has been approved by petrochenkov

It is now in the queue for this repository.

[bors]

⌛ Testing commit d45f025 with merge 4b8f431...

[bors]

☀️ Test successful - checks-actions
Approved by: petrochenkov
Pushing 4b8f431 to master...

[rust-timer]

Finished benchmarking commit (4b8f431): comparison URL.

Overall result: ✅ improvements - no action needed

@rustbot label: -perf-regression

Instruction count

This is a highly reliable metric that was used to determine the overall result at the top of this comment.

	mean1	range	count2
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.6%	[-0.7%, -0.6%]	2
Improvements ✅ (secondary)	-1.2%	[-1.6%, -0.6%]	7
All ❌✅ (primary)	-0.6%	[-0.7%, -0.6%]	2

Max RSS (memory usage)

Results

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.

	mean1	range	count2
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	2.4%	[2.1%, 2.8%]	3
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Cycles

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

Footnotes

1. the arithmetic mean of the percent change ↩ ↩²

2. number of relevant changes ↩ ↩²