delegation: store child segment flag in `PathSegment`#158556

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aerooneqq:delegation-child-segment-perf

aerooneqq commented Jun 29, 2026

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This should reduce perf overhead of checking whether path segment is a delegation's child segment.

r? @petrochenkov

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petrochenkov commented Jun 29, 2026

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@bors try @rust-timer queue

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rust-bors Bot pushed a commit that referenced this pull request


          Auto merge of #158556 - aerooneqq:delegation-child-segment-perf, r=<try>

ab95f53

delegation: store child segment flag in `PathSegment`

rust-bors Bot commented Jun 29, 2026

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☀️ Try build successful (CI)
Build commit: ab95f53 (ab95f53da0952e11b0180d3d6de83e807f1ec82b)
Base parent: 63f05e3 (63f05e3635171e7ac3f9ca78bad6c71052cda5a3)

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rust-timer commented Jun 29, 2026

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Finished benchmarking commit (ab95f53): comparison URL.

Overall result: no relevant changes - no action needed

Benchmarking means the PR may be perf-sensitive. Consider adding rollup=never if this change is not fit for rolling up.

@rustbot label: -S-waiting-on-perf -perf-regression

Instruction count

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

Max RSS (memory usage)

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

Cycles

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

Binary size

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

Bootstrap: 486.982s -> 486.289s (-0.14%)
Artifact size: 393.22 MiB -> 393.15 MiB (-0.02%)

rustbot removed the S-waiting-on-perf label

aerooneqq commented Jun 29, 2026

Contributor Author

There are no significant improvements, but many insignificant with significance factor 0.6 - 0.8, including typenum-1.18.0 which in regression PR had:

▶	typenum-1.18.0	check	incr-full	llvm	x64	0.11%	0.03%	4.12x
▶	typenum-1.18.0	opt	incr-full	llvm	x64	0.11%	0.03%	4.18x
▶	typenum-1.18.0	debug	incr-full	llvm	x64	0.11%	0.02%	4.63x

And in this PR:

▶	typenum-1.18.0	check	incr-full	llvm	x64	-0.12%	0.16%	0.79x
▶	typenum-1.18.0	opt	incr-full	llvm	x64	-0.12%	0.18%	0.68x
▶	typenum-1.18.0	debug	incr-full	llvm	x64	-0.12%	0.18%	0.68x

So I think we can consider perf regression from #157960 to be resolved here.

rustbot added S-waiting-on-review and removed S-waiting-on-author labels

aerooneqq marked this pull request as ready for review

June 29, 2026 13:19

rustbot commented Jun 29, 2026

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HIR ty lowering was modified

petrochenkov reviewed

View reviewed changes

compiler/rustc_hir/src/hir.rs

+                  /// Whether this segment is a delegation's child segment:
+                  /// `reuse Trait::foo`, in this case `foo` is a delegation's child segment.
+                  /// Used for faster check during generic args lowering.
+                  pub delegation_child_segment: bool,

petrochenkov Jun 29, 2026 •

edited by rustbot

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Note: the PathSegment's size doesn't change, there's a corresponding assert at the bottom of the file.

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compiler/rustc_hir/src/intravisit.rs Outdated

petrochenkov commented Jun 29, 2026

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r=me after addressing #158556 (comment).
@rustbot author
@bors delegate+

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rust-bors Bot commented Jun 29, 2026

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✌️ @aerooneqq, you can now approve this pull request!

If @petrochenkov told you to "r=me" after making some further change, then please make that change and post @bors r=petrochenkov.

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rustbot commented Jun 29, 2026

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Reminder, once the PR becomes ready for a review, use @rustbot ready.

petrochenkov mentioned this pull request

delegation: add support for infers in generics #157960

Merged


          Inline information of whether this segment is delegation's child segm…

91a762b

…ent into `PathSegment`

aerooneqq force-pushed the delegation-child-segment-perf branch from 2bee069 to 91a762b Compare

June 29, 2026 13:54

aerooneqq commented Jun 29, 2026

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@bors r=petrochenkov

rust-bors Bot commented Jun 29, 2026

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📌 Commit 91a762b has been approved by petrochenkov

It is now in the queue for this repository.

rust-bors Bot added S-waiting-on-bors and removed S-waiting-on-author labels

jhpratt added a commit to jhpratt/rust that referenced this pull request


          Rollup merge of rust-lang#158556 - aerooneqq:delegation-child-segment…

f6d6cd5

…-perf, r=petrochenkov

delegation: store child segment flag in `PathSegment`

This should reduce [perf overhead](rust-lang#157960 (comment)) of checking whether path segment is a delegation's child segment.

r? @petrochenkov

jhpratt mentioned this pull request

Rollup of 12 pull requests #158570

Closed

rust-bors Bot pushed a commit that referenced this pull request


          Auto merge of #158570 - jhpratt:rollup-8JjJt7Q, r=jhpratt

4bd48b9

Rollup of 12 pull requests

Successful merges:

 - #158073 (bootstrap: fix panic when repo path contains spaces by switching to CARGO_ENCODED_RUSTFLAGS)
 - #158169 (Fix debuginfo compression in bootstrap)
 - #158256 (Avoid parser panics bubbling out to proc macros)
 - #158375 (Support `DefKind::InlineConst` in `ConstKind::Unevaluated`)
 - #158417 (Avoid ICE when cfg_eval recovers no item from derive input)
 - #158556 (delegation: store child segment flag in `PathSegment`)
 - #158561 (Avoid building rustdoc for tests without doctests)
 - #158562 (Improve tracing of steps in bootstrap)
 - #157445 (Allow section override when using patchable-function-entries)
 - #158081 (trait-system: Recover deferred closure calls after errors)
 - #158327 (Move attribute and keyword docs from `std` to `core`)
 - #158468 (Include default-stability info in rustdoc JSON.)

JonathanBrouwer added a commit to JonathanBrouwer/rust that referenced this pull request


          Rollup merge of rust-lang#158556 - aerooneqq:delegation-child-segment…

36edf51

…-perf, r=petrochenkov

delegation: store child segment flag in `PathSegment`

This should reduce [perf overhead](rust-lang#157960 (comment)) of checking whether path segment is a delegation's child segment.

r? @petrochenkov

JonathanBrouwer mentioned this pull request

Rollup of 14 pull requests #158578

Closed

JonathanBrouwer added a commit to JonathanBrouwer/rust that referenced this pull request


          Rollup merge of rust-lang#158556 - aerooneqq:delegation-child-segment…

2ae791e

…-perf, r=petrochenkov

delegation: store child segment flag in `PathSegment`

This should reduce [perf overhead](rust-lang#157960 (comment)) of checking whether path segment is a delegation's child segment.

r? @petrochenkov

JonathanBrouwer mentioned this pull request

Rollup of 14 pull requests #158581

Closed

JonathanBrouwer added a commit to JonathanBrouwer/rust that referenced this pull request


          Rollup merge of rust-lang#158556 - aerooneqq:delegation-child-segment…

f1573f1

…-perf, r=petrochenkov

delegation: store child segment flag in `PathSegment`

This should reduce [perf overhead](rust-lang#157960 (comment)) of checking whether path segment is a delegation's child segment.

r? @petrochenkov

JonathanBrouwer mentioned this pull request

Rollup of 16 pull requests #158584

Closed

rust-bors Bot pushed a commit that referenced this pull request


          Auto merge of #158584 - JonathanBrouwer:rollup-pJvyPji, r=JonathanBro…

a196d08

…uwer

Rollup of 16 pull requests

Successful merges:

 - #155722 (Introduce aarch64-unknown-linux-pauthtest target)
 - #156230 (tests: check wasm compiler_builtins object architecture)
 - #158073 (bootstrap: fix panic when repo path contains spaces by switching to CARGO_ENCODED_RUSTFLAGS)
 - #158169 (Fix debuginfo compression in bootstrap)
 - #158256 (Avoid parser panics bubbling out to proc macros)
 - #158375 (Support `DefKind::InlineConst` in `ConstKind::Unevaluated`)
 - #158556 (delegation: store child segment flag in `PathSegment`)
 - #158561 (Avoid building rustdoc for tests without doctests)
 - #158562 (Improve tracing of steps in bootstrap)
 - #157445 (Allow section override when using patchable-function-entries)
 - #158081 (trait-system: Recover deferred closure calls after errors)
 - #158327 (Move attribute and keyword docs from `std` to `core`)
 - #158468 (Include default-stability info in rustdoc JSON.)
 - #158564 (fix `-Z min-recursion-limit` unstable chapter name)
 - #158568 (llvm-wrapper: use accessors for private fields in LLVM 23+)
 - #158582 (Comment on needed RAM in huge-stacks.rs)

rust-bors Bot pushed a commit that referenced this pull request


          Auto merge of #158584 - JonathanBrouwer:rollup-pJvyPji, r=JonathanBro…

e98c46d

…uwer

Rollup of 16 pull requests

Successful merges:

 - #155722 (Introduce aarch64-unknown-linux-pauthtest target)
 - #156230 (tests: check wasm compiler_builtins object architecture)
 - #158073 (bootstrap: fix panic when repo path contains spaces by switching to CARGO_ENCODED_RUSTFLAGS)
 - #158169 (Fix debuginfo compression in bootstrap)
 - #158256 (Avoid parser panics bubbling out to proc macros)
 - #158375 (Support `DefKind::InlineConst` in `ConstKind::Unevaluated`)
 - #158556 (delegation: store child segment flag in `PathSegment`)
 - #158561 (Avoid building rustdoc for tests without doctests)
 - #158562 (Improve tracing of steps in bootstrap)
 - #157445 (Allow section override when using patchable-function-entries)
 - #158081 (trait-system: Recover deferred closure calls after errors)
 - #158327 (Move attribute and keyword docs from `std` to `core`)
 - #158468 (Include default-stability info in rustdoc JSON.)
 - #158564 (fix `-Z min-recursion-limit` unstable chapter name)
 - #158568 (llvm-wrapper: use accessors for private fields in LLVM 23+)
 - #158582 (Comment on needed RAM in huge-stacks.rs)

JonathanBrouwer added a commit to JonathanBrouwer/rust that referenced this pull request


          Rollup merge of rust-lang#158556 - aerooneqq:delegation-child-segment…

1d86eaa

…-perf, r=petrochenkov

delegation: store child segment flag in `PathSegment`

This should reduce [perf overhead](rust-lang#157960 (comment)) of checking whether path segment is a delegation's child segment.

r? @petrochenkov

JonathanBrouwer mentioned this pull request

Rollup of 11 pull requests #158593

Open

rust-bors Bot pushed a commit that referenced this pull request


          Auto merge of #158593 - JonathanBrouwer:rollup-tGO5Zmu, r=JonathanBro…

e9c0998

…uwer

Rollup of 11 pull requests

Successful merges:

 - #155722 (Introduce aarch64-unknown-linux-pauthtest target)
 - #156230 (tests: check wasm compiler_builtins object architecture)
 - #156295 (Pass the whole `GenericArgs` to `Interner::for_each_relevant_impl()`)
 - #158375 (Support `DefKind::InlineConst` in `ConstKind::Unevaluated`)
 - #158556 (delegation: store child segment flag in `PathSegment`)
 - #158081 (trait-system: Recover deferred closure calls after errors)
 - #158468 (Include default-stability info in rustdoc JSON.)
 - #158543 (Note usage of documentation hard links in `core::io`)
 - #158564 (fix `-Z min-recursion-limit` unstable chapter name)
 - #158568 (llvm-wrapper: use accessors for private fields in LLVM 23+)
 - #158582 (Comment on needed RAM in huge-stacks.rs)

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