Perf regression fix

[Kivooeo]

The only thing changed from the previous PR is that I removed output_is_inhabited from hot path, and hide it behind condition, so now it will compute it less frequent

follow up on #149664

[Kivooeo]

@rust-timer build 9124eca

[Kivooeo]

@Kobzol how do i run this

[Kobzol]

@bors try @rust-timer queue

[rust-bors]

☀️ Try build successful (CI)
Build commit: 48c5d38 (48c5d3879672c42316e3b17a082885381ab2cfb9, parent: 95a27adcf907bcc1046602c3746dad8cfdf3bf3f)

[rust-timer]

Finished benchmarking commit (48c5d38): 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)	-0.2%	[-0.3%, -0.2%]	19
Improvements ✅ (secondary)	-0.3%	[-0.4%, -0.2%]	12
All ❌✅ (primary)	-0.2%	[-0.3%, -0.2%]	19

Max RSS (memory usage)

Results (primary 2.1%, secondary 2.2%)

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

	mean	range	count
Regressions ❌ (primary)	2.1%	[2.1%, 2.1%]	1
Regressions ❌ (secondary)	2.2%	[2.2%, 2.2%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	2.1%	[2.1%, 2.1%]	1

Cycles

Results (secondary -2.7%)

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)	-2.7%	[-2.9%, -2.5%]	2
All ❌✅ (primary)	-	-	0

Binary size

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

Bootstrap: 479.485s -> 478.535s (-0.20%)
Artifact size: 390.32 MiB -> 390.28 MiB (-0.01%)

[Kivooeo]

hm, wait how do I even understand if perf is fine? is there a way to check perf between two commits? I believe there's been a numerous amount of changes in this period of time that affects a bootstrap time

but on the other hand it's not a 5 second reduce, not sure how to interpret this results

[Kobzol]

Bootstrap time is not super important here, I would say. Based on the icount results, it looks like this change does indeed fix the regression!

[rustbot]

r? @SparrowLii

rustbot has assigned @SparrowLii.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

Use r? to explicitly pick a reviewer

[Kivooeo]

r? @davidtwco

[Kivooeo]

Based on the icount results, it looks like this change does indeed fix the regression!

Ah, thanks for the clarification!

[Kivooeo]

I want to try different approach, should be even better, do I need to rerun bors try before next perf run?

[Kobzol]

Yes, rustc-perf always benchmarks the result of the try build :)

@bors try @rust-timer queue

[rust-bors]

☀️ Try build successful (CI)
Build commit: da3c48f (da3c48f3bacfa34354f911642899ba5eb24ea620, parent: 31010ca61c3ff019e1480dda0a7ef16bd2bd51c0)

[rust-timer]

Finished benchmarking commit (da3c48f): 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)	-0.2%	[-0.3%, -0.2%]	18
Improvements ✅ (secondary)	-0.3%	[-0.4%, -0.2%]	10
All ❌✅ (primary)	-0.2%	[-0.3%, -0.2%]	18

Max RSS (memory usage)

Results (primary 2.0%, secondary -0.3%)

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

	mean	range	count
Regressions ❌ (primary)	2.0%	[2.0%, 2.0%]	1
Regressions ❌ (secondary)	4.3%	[4.3%, 4.3%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.6%	[-3.0%, -2.3%]	2
All ❌✅ (primary)	2.0%	[2.0%, 2.0%]	1

Cycles

Results (secondary 3.1%)

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)	3.1%	[3.1%, 3.1%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Binary size

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

Bootstrap: 479.038s -> 478.549s (-0.10%)
Artifact size: 390.32 MiB -> 390.27 MiB (-0.01%)

[Kivooeo]

looks slightly better right?

[Kobzol]

Looks pretty much the same to me.

[Kivooeo]

Nominate this to beta backport as was discussed on todays triage meeting because it's a follow up on a beta accepted PR

@rustbot label +beta-nominated

[davidtwco]

@bors r+

[bors]

📌 Commit fc0d01b has been approved by davidtwco

It is now in the queue for this repository.

[bors]

⌛ Testing commit fc0d01b with merge 806c2a3...