Revert "early return on duplicate span lowerings"

[jdonszelmann]

r? @nnethercote

reverts #149060 because of perf regressions that are still wild to me

[Kobzol]

@bors try @rust-timer qeueu

[rust-timer]

Command cannot be empty

[Kobzol]

@rust-timer queue

[nnethercote]

r=me assuming CI results improve perf as expected.

View changes since this review

[rust-bors]

☀️ Try build successful (CI)
Build commit: 27357a8 (27357a8796972732fc079d7ac78205ab2fdc7545, parent: 03d7ad7dd67d71f1ef1a790fcb4ceb2484ced761)

[rust-timer]

Finished benchmarking commit (27357a8): 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)	-0.3%	[-0.7%, -0.1%]	71
Improvements ✅ (secondary)	-0.4%	[-0.8%, -0.0%]	72
All ❌✅ (primary)	-0.3%	[-0.7%, -0.1%]	71

Max RSS (memory usage)

Results (primary -0.4%, 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)	1.6%	[1.6%, 1.6%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-2.3%	[-2.3%, -2.3%]	1
Improvements ✅ (secondary)	-2.7%	[-2.7%, -2.7%]	1
All ❌✅ (primary)	-0.4%	[-2.3%, 1.6%]	2

Cycles

Results (primary -2.4%, secondary -2.8%)

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)	-2.4%	[-2.5%, -2.2%]	2
Improvements ✅ (secondary)	-2.8%	[-4.2%, -1.3%]	2
All ❌✅ (primary)	-2.4%	[-2.5%, -2.2%]	2

Binary size

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

Bootstrap: 472.922s -> 471.827s (-0.23%)
Artifact size: 389.01 MiB -> 388.96 MiB (-0.01%)

[Kobzol]

Looks like the regression was real.

[jdonszelmann]

@bors r=nnethercote

[bors]

📌 Commit 942a08b has been approved by nnethercote

It is now in the queue for this repository.

[bors]

⌛ Testing commit 942a08b with merge e2893f7...

[bors]

☀️ Test successful - checks-actions
Approved by: nnethercote
Pushing e2893f7 to main...

[github-actions]

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 d5525a7 (parent) -> e2893f7 (this PR)

Test differences

Show 3 test diffs

3 doctest diffs were found. These are ignored, as they are noisy.

Test dashboard

Run

cargo run --manifest-path src/ci/citool/Cargo.toml -- \
    test-dashboard e2893f7c95e45f74c8bc5dbd033486c5bfaa4deb --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

1. aarch64-gnu-llvm-20-2: 2493.4s -> 2086.6s (-16.3%)
2. x86_64-gnu-llvm-20-2: 6031.4s -> 5110.6s (-15.3%)
3. x86_64-gnu-llvm-20: 2822.1s -> 2399.9s (-15.0%)
4. i686-gnu-nopt-1: 8685.2s -> 7405.3s (-14.7%)
5. x86_64-gnu-gcc: 3514.4s -> 3003.9s (-14.5%)
6. dist-aarch64-llvm-mingw: 5732.6s -> 6556.2s (+14.4%)
7. aarch64-gnu-llvm-20-1: 3927.0s -> 3379.4s (-13.9%)
8. x86_64-rust-for-linux: 3220.6s -> 2807.8s (-12.8%)
9. x86_64-gnu-llvm-20-3: 6564.3s -> 5752.6s (-12.4%)
10. dist-aarch64-msvc: 5434.6s -> 6104.0s (+12.3%)

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]

Finished benchmarking commit (e2893f7): 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

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)	0.1%	[0.1%, 0.1%]	1
Improvements ✅ (primary)	-0.3%	[-0.7%, -0.1%]	69
Improvements ✅ (secondary)	-0.3%	[-0.8%, -0.0%]	71
All ❌✅ (primary)	-0.3%	[-0.7%, -0.1%]	69

Max RSS (memory usage)

Results (primary -2.5%)

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)	-2.5%	[-2.5%, -2.5%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-2.5%	[-2.5%, -2.5%]	1

Cycles

Results (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)	-	-	0
Regressions ❌ (secondary)	3.3%	[3.3%, 3.3%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.8%	[-2.8%, -2.8%]	1
All ❌✅ (primary)	-	-	0

Binary size

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

Bootstrap: 472.272s -> 471.528s (-0.16%)
Artifact size: 389.04 MiB -> 388.98 MiB (-0.01%)