early return on duplicate span lowerings

[jdonszelmann]

@bors2 try

[jdonszelmann]

@bors2 try @rust-timer queue

[rust-timer]

This pull request was already queued before and is awaiting a try build to finish.

[rust-bors]

☀️ Try build successful (CI)
Build commit: a0c110f (a0c110f657f885a3fe1c9415cbffa402f2be5cb3, parent: f9e7961506a97b318ad4815b8ce94bb045562f89)

[rust-timer]

Finished benchmarking commit (a0c110f): 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)	0.1%	[0.1%, 0.1%]	2
Regressions ❌ (secondary)	0.2%	[0.2%, 0.2%]	7
Improvements ✅ (primary)	-0.8%	[-2.9%, -0.1%]	4
Improvements ✅ (secondary)	-0.6%	[-0.6%, -0.6%]	3
All ❌✅ (primary)	-0.5%	[-2.9%, 0.1%]	6

Max RSS (memory usage)

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

Cycles

Results (primary -2.4%, 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)	2.7%	[2.7%, 2.7%]	1
Improvements ✅ (primary)	-2.4%	[-2.4%, -2.4%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-2.4%	[-2.4%, -2.4%]	1

Binary size

Results (primary -1.1%)

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)	-	-	0
Improvements ✅ (primary)	-1.1%	[-1.1%, -1.1%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-1.1%	[-1.1%, -1.1%]	1

Bootstrap: 471.624s -> 473.081s (0.31%)
Artifact size: 388.73 MiB -> 388.78 MiB (0.01%)

[jdonszelmann]

welp, that seems worth it

[jdonszelmann]

lemme clean it up and mark it ready

[jdonszelmann]

r? @oli-obk

[rustbot]

oli-obk is not on the review rotation at the moment.
They may take a while to respond.