perf: skip irrelevant foreign impls when building the specialization graph by xmakro · Pull Request #157281 · rust-lang/rust

xmakro · 2026-06-02T03:18:57Z

Skip foreign non-blanket impls that can't overlap any local impl when building the specialization graph. The call site showed up when profiling and this PR leads to a mean -1.5% instructions perf improvement, see #157281 (comment)

cjgillot · 2026-06-04T19:12:05Z

@bors try @rust-timer queue

…<try> perf: Skip irrelevant foreign impls when building the specialization graph

rust-bors · 2026-06-05T01:20:20Z

💥 Test timed out after 21600s

xmakro · 2026-06-10T16:34:08Z

@cjgillot could you please retry rust-timer

Kobzol · 2026-06-10T16:57:36Z

@bors try @rust-timer queue

…<try> perf: skip irrelevant foreign impls when building the specialization graph

rust-bors · 2026-06-10T19:09:07Z

☀️ Try build successful (CI)
Build commit: 55fd877 (55fd87784ebf6c3bcb3d43089182c710005c85d3, parent: 485ec3fbcc12fa14ef6596dabb125ad710499c9e)

rust-timer · 2026-06-10T19:49:28Z

Finished benchmarking commit (55fd877): comparison URL.

Overall result: ✅ improvements - no action needed

Benchmarking means the PR may be perf-sensitive. It's automatically marked not fit for rolling up. Overriding is possible but disadvised: it risks changing 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)	1.8%	[1.8%, 1.8%]	1
Improvements ✅ (primary)	-1.5%	[-5.8%, -0.2%]	189
Improvements ✅ (secondary)	-3.2%	[-19.8%, -0.1%]	133
All ❌✅ (primary)	-1.5%	[-5.8%, -0.2%]	189

Max RSS (memory usage)

Results (primary -2.2%, 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)	-2.2%	[-5.5%, -0.6%]	112
Improvements ✅ (secondary)	-2.8%	[-5.2%, -0.5%]	69
All ❌✅ (primary)	-2.2%	[-5.5%, -0.6%]	112

Cycles

Results (primary -4.2%, secondary -8.1%)

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)	-4.2%	[-7.3%, -1.8%]	61
Improvements ✅ (secondary)	-8.1%	[-19.2%, -1.3%]	52
All ❌✅ (primary)	-4.2%	[-7.3%, -1.8%]	61

Binary size

This perf run didn't have relevant results for this metric.

Bootstrap: 517.006s -> 513.501s (-0.68%)
Artifact size: 401.43 MiB -> 400.97 MiB (-0.11%)

xmakro · 2026-06-15T17:01:41Z

@cjgillot would you be comfortable reviewing this PR? or maybe someone from the types team? thanks!

xmakro · 2026-06-28T02:04:34Z

r? types

xmakro · 2026-07-23T20:18:03Z

cc @nnethercote who might be interested

jackh726 · 2026-08-04T03:15:09Z

Seems reasonable...

@bors r+

rust-bors · 2026-08-04T03:15:11Z

📌 Commit 1ddeb9a has been approved by jackh726

It is now in the queue for this repository.

JonathanBrouwer · 2026-08-04T12:39:46Z

@bors rollup=iffy
Including this in a special perf-sensitive rollup

…uwer Rollup of 10 perf-sensitive pull requests Successful merges: - #157281 (perf: skip irrelevant foreign impls when building the specialization graph) - #159403 (Next steps for FnDef binder changes (instantiate most FnDef binders)) - #159763 (Optimize crate resolution for large workspace) - #160033 (Speed up `EverInitializedPlaces`) - #160268 (perf: store the fulfillment engine inline in ObligationCtxt) - #160317 (perf: Cache already-checked types in the privacy visitor) - #160399 (interpret: skip deref-projection validity checks when they are not needed) - #160451 (Deduplicate target and host filesearch) - #160453 (Add fast path to `escape_string_symbol`) - #160454 (Add offload guard flags to typeck to prevent perf regressions)

Rollup merge of #157281 - xmakro:perf/spec-graph-skip-foreign-impls, r=jackh726 perf: skip irrelevant foreign impls when building the specialization graph Skip foreign non-blanket impls that can't overlap any local impl when building the specialization graph. The call site showed up when profiling and this PR leads to a mean -1.5% instructions perf improvement, see #157281 (comment)

JonathanBrouwer · 2026-08-05T06:39:47Z

Verifying that actual perf results after merge match expected results
@rust-timer build 6e2e027

rust-timer · 2026-08-05T07:38:18Z

Finished benchmarking commit (6e2e027): comparison URL.

Overall result: ✅ improvements - no action needed

Benchmarking means the PR may be perf-sensitive. It's automatically marked not fit for rolling up. Overriding is possible but disadvised: it risks changing compiler perf.

@bors rollup=never rustc-perf
@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)	-1.5%	[-6.1%, -0.2%]	209
Improvements ✅ (secondary)	-3.2%	[-19.7%, -0.1%]	137
All ❌✅ (primary)	-1.5%	[-6.1%, -0.2%]	209

Max RSS (memory usage)

Results (primary -2.0%, 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)	1.4%	[1.0%, 1.9%]	2
Regressions ❌ (secondary)	2.4%	[0.7%, 4.2%]	2
Improvements ✅ (primary)	-2.0%	[-4.1%, -0.4%]	138
Improvements ✅ (secondary)	-2.7%	[-6.1%, -0.4%]	83
All ❌✅ (primary)	-2.0%	[-4.1%, 1.9%]	140

Cycles

Results (primary -3.5%, secondary -6.4%)

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

	mean	range	count
Regressions ❌ (primary)	0.6%	[0.6%, 0.6%]	1
Regressions ❌ (secondary)	0.8%	[0.6%, 1.1%]	3
Improvements ✅ (primary)	-3.5%	[-7.6%, -0.7%]	85
Improvements ✅ (secondary)	-6.7%	[-20.4%, -0.5%]	70
All ❌✅ (primary)	-3.5%	[-7.6%, 0.6%]	86

Binary size

This perf run didn't have relevant results for this metric.

Bootstrap: 489.577s -> 487.42s (-0.44%)
Artifact size: 390.24 MiB -> 390.39 MiB (0.04%)

…r=jackh726 perf: skip irrelevant foreign impls when building the specialization graph Skip foreign non-blanket impls that can't overlap any local impl when building the specialization graph. The call site showed up when profiling and this PR leads to a mean -1.5% instructions perf improvement, see rust-lang/rust#157281 (comment)

…uwer Rollup of 10 perf-sensitive pull requests Successful merges: - rust-lang/rust#157281 (perf: skip irrelevant foreign impls when building the specialization graph) - rust-lang/rust#159403 (Next steps for FnDef binder changes (instantiate most FnDef binders)) - rust-lang/rust#159763 (Optimize crate resolution for large workspace) - rust-lang/rust#160033 (Speed up `EverInitializedPlaces`) - rust-lang/rust#160268 (perf: store the fulfillment engine inline in ObligationCtxt) - rust-lang/rust#160317 (perf: Cache already-checked types in the privacy visitor) - rust-lang/rust#160399 (interpret: skip deref-projection validity checks when they are not needed) - rust-lang/rust#160451 (Deduplicate target and host filesearch) - rust-lang/rust#160453 (Add fast path to `escape_string_symbol`) - rust-lang/rust#160454 (Add offload guard flags to typeck to prevent perf regressions)

rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Jun 2, 2026

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xmakro force-pushed the perf/spec-graph-skip-foreign-impls branch from 290c594 to 52e8f33Compare June 2, 2026 16:55

xmakro changed the title ~~Skip irrelevant foreign impls when building the specialization graph~~perf: Skip irrelevant foreign impls when building the specialization graphJun 3, 2026

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rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Jun 4, 2026

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rust-borsBot pushed a commit that referenced this pull request Jun 4, 2026
Auto merge of#157281- xmakro:perf/spec-graph-skip-foreign-impls, r=…
5ba91f2
…<try> perf: Skip irrelevant foreign impls when building the specialization graph

xmakro force-pushed the perf/spec-graph-skip-foreign-impls branch from 52e8f33 to 0eef947Compare June 5, 2026 11:51

xmakro changed the title ~~perf: Skip irrelevant foreign impls when building the specialization graph~~perf: skip irrelevant foreign impls when building the specialization graphJun 5, 2026

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rust-borsBot pushed a commit that referenced this pull request Jun 10, 2026
Auto merge of#157281- xmakro:perf/spec-graph-skip-foreign-impls, r=…
55fd877
…<try> perf: skip irrelevant foreign impls when building the specialization graph

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rustbot removed the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Jun 10, 2026

xmakro closed this Jun 11, 2026

rustbot removed the S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. label Jun 11, 2026

xmakro reopened this Jun 11, 2026

rustbot added the S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. label Jun 11, 2026

Skip irrelevant foreign impls when building the specialization graph
1ddeb9a

xmakro force-pushed the perf/spec-graph-skip-foreign-impls branch from 0eef947 to 1ddeb9aCompare June 11, 2026 02:39

rustbot added the T-types Relevant to the types team, which will review and decide on the PR/issue. label Jun 28, 2026

rustbot assigned jackh726 Jun 28, 2026

xmakro marked this pull request as ready for review June 28, 2026 02:04

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jun 28, 2026

rust-borsBot added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Aug 4, 2026

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JonathanBrouwer mentioned this pull request Aug 4, 2026
Rollup of 10 perf-sensitive pull requests #160506
Merged

rust-borsBot merged commit e18f209 into rust-lang:mainAug 4, 2026
12 checks passed

rustbot added this to the 1.99.0 milestone Aug 4, 2026

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rust-timer commented Jun 10, 2026

Overall result: ✅ improvements - no action needed

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rust-timer commented Aug 5, 2026

Overall result: ✅ improvements - no action needed

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xmakro commented Jun 2, 2026•
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