Optimize crate resolution for large workspace by nikic · Pull Request #159763 · rust-lang/rust

nikic · 2026-07-23T10:28:06Z

By keeping a map from hash to crate number.

nikic · 2026-07-23T10:28:43Z

Optimize crate resolution for large workspace

rust-bors · 2026-07-23T12:33:52Z

☀️ Try build successful (CI)
Build commit: dd1f563 (dd1f5634c7540ca852bd1c09e61c8b203a8e5799)
Base parent: 390279b (390279b302ca98ae270f434100ae3730531d1246)

rust-timer · 2026-07-23T13:14:23Z

Finished benchmarking commit (dd1f563): 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)	-	-	0
Improvements ✅ (secondary)	-7.6%	[-15.9%, -1.7%]	10
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary 2.7%, secondary 4.2%)

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

	mean	range	count
Regressions ❌ (primary)	2.7%	[2.7%, 2.7%]	1
Regressions ❌ (secondary)	4.2%	[2.7%, 5.4%]	3
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	2.7%	[2.7%, 2.7%]	1

Cycles

Results (secondary -1.5%)

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)	10.9%	[3.0%, 25.7%]	3
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-5.2%	[-9.1%, -3.0%]	10
All ❌✅ (primary)	-	-	0

Binary size

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

Bootstrap: 486.724s -> 486.28s (-0.09%)
Artifact size: 387.61 MiB -> 387.61 MiB (0.00%)

rustbot · 2026-07-23T13:16:04Z

r? @davidtwco

rustbot has assigned @davidtwco.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

Use r? to explicitly pick a reviewer

Why was this reviewer chosen?

The reviewer was selected based on:

Owners of files modified in this PR: compiler
compiler expanded to 74 candidates
Random selection from 20 candidates

By keeping a map from hash to crate number.

bjorn3 · 2026-07-23T14:21:27Z

Great find by the way!

Kobzol · 2026-08-04T08:08:09Z

@rustbot reroll

Kobzol · 2026-08-04T08:08:43Z

Or maybe @bjorn3 can you r+ it, since you looked at it, to avoid review ping pong? :)

bjorn3 · 2026-08-04T08:28:20Z

r? bjorn3

@bors r+

rust-bors · 2026-08-04T08:28:23Z

📌 Commit 54ff9a2 has been approved by bjorn3

It is now in the queue for this repository.

🌲 The tree is currently closed for pull requests below priority 10. This pull request will be tested once the tree is reopened.

Reason for tree closure: manually handling queue due to backlog

Kobzol · 2026-08-04T11:00:53Z

Marking as rollup=iffy, because this only affects one benchmark, and we have a lot of rollup=never PRs in the queue.

@bors rollup=iffy

…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 #159763 - nikic:resolve-crate-opt, r=bjorn3 Optimize crate resolution for large workspace By keeping a map from hash to crate number.

JonathanBrouwer · 2026-08-05T06:40:11Z

Verifying that actual perf results after merge match expected results
@rust-timer build 2f596f7

…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)

rust-timer · 2026-08-05T09:02:04Z

Finished benchmarking commit (2f596f7): 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)	-	-	0
Improvements ✅ (secondary)	-7.5%	[-15.3%, -1.7%]	11
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary -0.1%, secondary -0.4%)

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

	mean	range	count
Regressions ❌ (primary)	1.0%	[0.4%, 1.6%]	2
Regressions ❌ (secondary)	0.7%	[0.7%, 0.7%]	1
Improvements ✅ (primary)	-2.3%	[-2.3%, -2.3%]	1
Improvements ✅ (secondary)	-1.0%	[-1.2%, -0.7%]	2
All ❌✅ (primary)	-0.1%	[-2.3%, 1.6%]	3

Cycles

Results (primary 0.4%, 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)	0.9%	[0.5%, 1.6%]	7
Regressions ❌ (secondary)	1.0%	[0.7%, 1.6%]	4
Improvements ✅ (primary)	-1.2%	[-1.3%, -1.1%]	2
Improvements ✅ (secondary)	-4.1%	[-10.2%, -0.7%]	12
All ❌✅ (primary)	0.4%	[-1.3%, 1.6%]	9

Binary size

Results (primary -0.0%, 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
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.0%	[-0.1%, -0.0%]	8
Improvements ✅ (secondary)	-0.1%	[-0.1%, -0.0%]	35
All ❌✅ (primary)	-0.0%	[-0.1%, -0.0%]	8

Bootstrap: 489.577s -> 488.839s (-0.15%)
Artifact size: 390.24 MiB -> 390.29 MiB (0.01%)

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 Jul 23, 2026

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rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Jul 23, 2026

rust-bors Bot pushed a commit that referenced this pull request Jul 23, 2026

Auto merge of #159763 - nikic:resolve-crate-opt, r=<try>

dd1f563

Optimize crate resolution for large workspace

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nikic mentioned this pull request Jul 23, 2026

Update to LLVM 23 #158734

Merged

9 tasks

rustbot removed the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Jul 23, 2026

nikic marked this pull request as ready for review July 23, 2026 13:16

rustbot added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jul 23, 2026

rustbot assigned davidtwco Jul 23, 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 Jul 23, 2026

bjorn3 reviewed Jul 23, 2026

View reviewed changes

Comment thread compiler/rustc_metadata/src/creader.rs Outdated

Optimize crate resolution

54ff9a2

By keeping a map from hash to crate number.

nikic force-pushed the resolve-crate-opt branch from 89418e2 to 54ff9a2 Compare July 23, 2026 14:17

rustbot assigned khyperia and unassigned davidtwco Aug 4, 2026

rustbot assigned bjorn3 Aug 4, 2026

rust-bors Bot added the S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. label Aug 4, 2026

rustbot unassigned khyperia Aug 4, 2026

rust-bors Bot removed the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Aug 4, 2026

JonathanBrouwer mentioned this pull request Aug 4, 2026

Rollup of 10 perf-sensitive pull requests #160506

Merged

rust-bors Bot merged commit adf7af8 into rust-lang:main Aug 4, 2026
13 checks passed

rustbot added this to the 1.99.0 milestone Aug 4, 2026

rust-timer added a commit that referenced this pull request Aug 4, 2026

Unrolled build for #159763

2f596f7

Rollup merge of #159763 - nikic:resolve-crate-opt, r=bjorn3 Optimize crate resolution for large workspace By keeping a map from hash to crate number.

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Overall result: ✅ improvements - no action needed

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Overall result: ✅ improvements - no action needed

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