Use Box<[T]> for ProcessResult::Changed

[GnomedDev]

Using a boxed slice here should save moving around the capacity when it's equal, and maybe save some memory as this automatically shrink_to_fits.

[rustbot]

r? @estebank

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[compiler-errors]

@bors try @rust-timer queue

[bors]

⌛ Trying commit f9e71fc with merge 5140237...

[bors]

☀️ Try build successful - checks-actions
Build commit: 5140237 (5140237979808f031043c5a318f5ce8beb0564fe)

[rust-timer]

Finished benchmarking commit (5140237): 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 a highly reliable metric that was 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)	-2.1%	[-2.1%, -2.1%]	1
All ❌✅ (primary)	-	-	0

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.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	2.5%	[2.5%, 2.5%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.6%	[-3.0%, -2.2%]	2
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.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	2.7%	[2.7%, 2.7%]	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: 641.255s -> 639.801s (-0.23%)
Artifact size: 308.58 MiB -> 308.60 MiB (0.01%)

[compiler-errors]

Probably noise. I don't think we should land this, since it just adds extra complexity.

[GnomedDev]

I don't see how this is extra complexity? Boxed slices are less complex than Vecs.

[estebank]

@compiler-errors the only metric affected does have a >1x significance factor, and the over all changes seem slightly annoying simply because vec is such a common construct, but it doesn't seem worth it to block this due to that?

@GnomedDev apologies for the delay in reviewing this again, it fell of my radar.

[estebank]

I'm +1, but want to discuss and arrive to the consensus with @compiler-errors

[compiler-errors]

Thanks, but I don't think this is worth the change. If this were actually significantly affecting the processing of obligations in fulfillment, then we would see more than a single benchmark improve here; afaict, there's nothing particularly special about incr-full wrt fulfillment.