Remove boxes from ast list elements #146221

camsteffen · 2025-09-05T01:13:50Z

Less indirection should be better perf.

rustbot · 2025-09-05T01:13:55Z

rustbot has assigned @spastorino.
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rustbot · 2025-09-05T01:13:57Z

Some changes occurred in src/tools/clippy

cc @rust-lang/clippy

Some changes occurred in src/tools/rustfmt

cc @rust-lang/rustfmt

Some changes occurred in compiler/rustc_builtin_macros/src/autodiff.rs

cc @ZuseZ4

petrochenkov · 2025-09-05T12:01:50Z

Indirection is removed, but expansion may now do more work to box the stuff and then unbox it again.
@bors2 try @rust-timer queue

Remove boxes from ast list elements

rust-bors · 2025-09-05T14:22:01Z

☀️ Try build successful (CI)
Build commit: cd2fe74 (cd2fe744675bd21a03fe74405a44184f1dbf682e, parent: ad85bc524b1ad696e42061ad8338d382dffbdbe5)

rust-timer · 2025-09-05T16:13:40Z

Finished benchmarking commit (cd2fe74): 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
Regressions ❌ (secondary)	0.2%	[0.1%, 0.4%]	12
Improvements ✅ (primary)	-0.2%	[-0.2%, -0.1%]	4
Improvements ✅ (secondary)	-0.3%	[-0.4%, -0.1%]	8
All ❌✅ (primary)	-0.2%	[-0.2%, -0.1%]	4

Max RSS (memory usage)

Results (primary -0.6%, secondary -2.9%)

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)	-0.6%	[-0.6%, -0.6%]	1
Improvements ✅ (secondary)	-2.9%	[-3.2%, -2.6%]	3
All ❌✅ (primary)	-0.6%	[-0.6%, -0.6%]	1

Cycles

Results (primary 1.6%, secondary 2.6%)

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)	2.6%	[2.2%, 3.0%]	4
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	1.6%	[1.6%, 1.6%]	1

Binary size

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

Bootstrap: 467.829s -> 467.149s (-0.15%)
Artifact size: 390.58 MiB -> 390.60 MiB (0.00%)

camsteffen · 2025-09-05T16:39:26Z

Seems neutral/mixed with a bit of max RSS improvements?

camsteffen · 2025-09-06T22:41:50Z

Moved a Box::new to try and fix regressions. Profiling shows the regressions are in parse_param_general::{closure#0}.

ZuseZ4 · 2025-09-06T22:51:21Z

@bors2 try @rust-timer queue

Remove boxes from ast list elements

rust-bors · 2025-09-07T01:08:42Z

☀️ Try build successful (CI)
Build commit: 4c3b5d3 (4c3b5d3811bd68ed990231b0dcfaad8b5ab255af, parent: 1ed3cd7030718935a5c5e5c8f6581f36d8be179f)

rust-timer · 2025-09-07T02:23:25Z

Finished benchmarking commit (4c3b5d3): comparison URL.

Overall result: ❌ regressions - 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)	0.4%	[0.1%, 0.8%]	19
Regressions ❌ (secondary)	0.2%	[0.1%, 0.4%]	22
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.4%	[-0.5%, -0.3%]	3
All ❌✅ (primary)	0.4%	[0.1%, 0.8%]	19

Max RSS (memory usage)

Results (primary 1.3%, 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)	1.3%	[1.3%, 1.3%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.2%	[-3.4%, -0.7%]	4
All ❌✅ (primary)	1.3%	[1.3%, 1.3%]	1

Cycles

Results (primary 3.1%)

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

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

Binary size

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

Bootstrap: 465.747s -> 468.049s (0.49%)
Artifact size: 387.43 MiB -> 387.47 MiB (0.01%)

camsteffen · 2025-09-07T13:18:42Z

@rustbot author

rust-timer · 2025-10-03T00:30:31Z

Finished benchmarking commit (8474967): comparison URL.

Overall result: ❌ regressions - 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)	0.1%	[0.1%, 0.1%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary 0.8%, secondary 0.1%)

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

	mean	range	count
Regressions ❌ (primary)	0.8%	[0.7%, 0.8%]	2
Regressions ❌ (secondary)	1.4%	[0.9%, 2.6%]	4
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.5%	[-2.5%, -2.5%]	2
All ❌✅ (primary)	0.8%	[0.7%, 0.8%]	2

Cycles

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

Binary size

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

Bootstrap: 471.823s -> 471.318s (-0.11%)
Artifact size: 387.78 MiB -> 387.78 MiB (-0.00%)

rustbot · 2025-10-04T17:44:06Z

This PR was rebased onto a different master commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

This recovers some instruction count regressions after changing most Pat parsing functions return a non-boxed Pat. It seems to be beneficial to break out a #[cold] parsing recovery function when the function includes more parsing, presumably because this requires more stack space and/or mem copies when LLVM optimizes the wrong path.

camsteffen · 2025-10-04T18:26:21Z

Let's try again.

ZuseZ4 · 2025-10-05T01:48:35Z

@bors2 try @rust-timer queue

Remove boxes from ast list elements

rust-bors · 2025-10-05T07:52:41Z

💥 Test timed out after 21600s

camsteffen · 2025-10-07T20:22:26Z

@ZuseZ4 can you give it another try?

ZuseZ4 · 2025-10-07T20:25:56Z

@bors2 try @rust-timer queue

Remove boxes from ast list elements

rust-bors · 2025-10-07T22:41:32Z

☀️ Try build successful (CI)
Build commit: c10c5b1 (c10c5b1ea7de995e6ec34ef6dcda49324b4c2810, parent: fed46ffd5059e11669df1bd9406b02914c3fb73f)

rust-timer · 2025-10-08T00:59:29Z

Finished benchmarking commit (c10c5b1): comparison URL.

Overall result: ❌✅ regressions and 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)	0.2%	[0.2%, 0.2%]	1
Improvements ✅ (primary)	-0.2%	[-0.2%, -0.2%]	2
Improvements ✅ (secondary)	-0.0%	[-0.0%, -0.0%]	1
All ❌✅ (primary)	-0.2%	[-0.2%, -0.2%]	2

Max RSS (memory usage)

Results (primary -2.4%, secondary -0.8%)

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)	1.7%	[0.9%, 2.4%]	2
Improvements ✅ (primary)	-2.4%	[-3.2%, -1.6%]	2
Improvements ✅ (secondary)	-2.0%	[-2.6%, -0.6%]	4
All ❌✅ (primary)	-2.4%	[-3.2%, -1.6%]	2

Cycles

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

Binary size

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

Bootstrap: 474.165s -> 473.322s (-0.18%)
Artifact size: 388.38 MiB -> 388.39 MiB (0.00%)

camsteffen · 2025-10-08T02:25:29Z

This looks like a small win now. I think the one regression is noise.

@rustbot ready

rustbot assigned spastorino Sep 5, 2025