Remove the `TypedArena::alloc_from_iter` specialization. #116370

nnethercote · 2023-10-03T02:38:25Z

It was added in #78569. It's complicated and doesn't actually help
performance.

r? @cjgillot

rustbot · 2023-10-03T02:38:29Z

Some changes occurred in rustc_ty_utils::consts.rs

cc @BoxyUwU

nnethercote · 2023-10-03T02:38:35Z

@bors try @rust-timer queue

bors · 2023-10-03T02:39:44Z

⌛ Trying commit 2e5e49f with merge 39fc71a...

More arena stuff r? `@ghost`

bors · 2023-10-03T03:53:05Z

☀️ Try build successful - checks-actions
Build commit: 39fc71a (39fc71ad3375354924cb77fd2b30ff0757a0b8f8)

rust-timer · 2023-10-03T05:14:27Z

Finished benchmarking commit (39fc71a): comparison URL.

Overall result: no relevant changes - no action needed

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. While you can manually mark this PR as fit for rollup, we strongly recommend not doing so since this PR may lead to changes in compiler perf.

@bors rollup=never
@rustbot label: -S-waiting-on-perf -perf-regression

Instruction count

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

Max RSS (memory usage)

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-1.3%	[-1.7%, -1.0%]	4
Improvements ✅ (secondary)	-3.4%	[-3.4%, -3.4%]	1
All ❌✅ (primary)	-1.3%	[-1.7%, -1.0%]	4

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: 624.341s -> 623.869s (-0.08%)
Artifact size: 271.92 MiB -> 271.97 MiB (0.02%)

It was added in rust-lang#78569. It's complicated and doesn't actually help performance. Also, add a comment explaining why the two `alloc_from_iter` functions are so different.

There's no need to collect an iterator into a `Vec`, or to call `into_iter` at the call sites.

nnethercote · 2023-10-03T07:18:23Z

Perf is unchanged, I think this is good to go.

r? @cjgillot

cjgillot · 2023-10-04T11:51:49Z

compiler/rustc_arena/src/lib.rs

+        // Instead we use an approach where any iterator panic will occur
+        // before the memory is allocated. This function is much less hot than
+        // `DroplessArena::alloc_from_iter`, so it doesn't need to be
+        // hyper-optimized.


Do we need a fast path if !needs_drop::<T>()? That would call the drop-less codepath and eventually benefit from the opt.

Not sure I understand the question. Any T not implementing Drop will be allocated in the DroplessArena, as per this comment.

cjgillot · 2023-10-04T20:59:41Z

@bors r+

bors · 2023-10-04T20:59:43Z

📌 Commit a2051dd has been approved by cjgillot

It is now in the queue for this repository.

bors · 2023-10-04T22:32:49Z

⌛ Testing commit a2051dd with merge afe67fa...

bors · 2023-10-05T00:21:36Z

☀️ Test successful - checks-actions
Approved by: cjgillot
Pushing afe67fa to master...

rust-timer · 2023-10-05T02:55:57Z

Finished benchmarking commit (afe67fa): comparison URL.

Overall result: no relevant changes - no action needed

@rustbot label: -perf-regression

Instruction count

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

Max RSS (memory usage)

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

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: 623.37s -> 622.444s (-0.15%)
Artifact size: 272.00 MiB -> 272.02 MiB (0.01%)

Update Rust toolchain from nightly-2023-10-05 to nightly-2023-10-06 without any other source changes. This is an automatically generated pull request. If any of the CI checks fail, manual intervention is required. In such a case, review the changes at https://github.com/rust-lang/rust from rust-lang@2bbb619 up to rust-lang@cae0791. The log for this commit range is: rust-lang@cae0791da4 Auto merge of rust-lang#116417 - ouz-a:trait_type_detective, r=compiler-errors rust-lang@e30d27be00 remove is global hack rust-lang@cdca82c2c8 Auto merge of rust-lang#116455 - matthiaskrgr:rollup-p226a5u, r=matthiaskrgr rust-lang@76d0b794cb Rollup merge of rust-lang#116452 - cjgillot:noassert-erased, r=oli-obk rust-lang@c1c5ab717e Rollup merge of rust-lang#116428 - Alexendoo:note-duplicate-diagnostics, r=compiler-errors,estebank rust-lang@08cc7428d9 Rollup merge of rust-lang#116415 - ouz-a:move_subtyper, r=oli-obk rust-lang@b301bd4220 Rollup merge of rust-lang#116288 - ouz-a:smir_spans, r=spastorino rust-lang@864e5d8d94 Rollup merge of rust-lang#116220 - llogiq:stabilize-option-as-slice, r=BurntSushi rust-lang@3088c4b046 move subtyper change reveal_all rust-lang@14c846cb05 Do not assert that hidden types don't have erased regions. rust-lang@3bcad65fbf Auto merge of rust-lang#103046 - JanBeh:PR_clarify_cmp_terminology, r=workingjubilee rust-lang@cf9fd95b1c Auto merge of rust-lang#114042 - liushuyu:ubuntu/i586-fpmath, r=workingjubilee rust-lang@86b031b734 docs: Correct terminology in std::cmp rust-lang@90f3a6f920 Auto merge of rust-lang#104153 - tspiteri:doc-float-constants, r=workingjubilee rust-lang@5c3a0e932b Auto merge of rust-lang#116427 - cjgillot:no-internal, r=oli-obk rust-lang@a49138e46e impl stable for kinds rust-lang@a79567b01c add span to statements rust-lang@e293927016 Auto merge of rust-lang#116443 - workingjubilee:rollup-r9mh13f, r=workingjubilee rust-lang@4a14a80605 Rollup merge of rust-lang#116432 - notriddle:master, r=fmease rust-lang@d7b02c3d40 Rollup merge of rust-lang#116431 - estebank:issue-80476, r=compiler-errors rust-lang@a9a389cf44 Rollup merge of rust-lang#116429 - fmease:clean-up-struct-field-suggs, r=compiler-errors rust-lang@cfce3a919d Rollup merge of rust-lang#116296 - compiler-errors:default-return, r=estebank rust-lang@ea3454eabb Rollup merge of rust-lang#116223 - catandcoder:master, r=cjgillot rust-lang@5236c8e1fa Auto merge of rust-lang#116273 - compiler-errors:refine2, r=tmandry rust-lang@b781645332 Auto merge of rust-lang#116184 - compiler-errors:afit-lint, r=tmandry rust-lang@5453a9f34d Add a note to duplicate diagnostics rust-lang@afe67fa2ef Auto merge of rust-lang#116370 - nnethercote:more-arena-stuff, r=cjgillot rust-lang@2f5249019e Apply suggestions from code review rust-lang@dd5f26c42d Fix spans for comments in rustfmt rust-lang@1f079cfb44 Point to closure return instead of output if defaulted rust-lang@89b14ae212 Fix clippy rust-lang@137b6d0b01 Point to where missing return type should go rust-lang@a46ccd8d3f Add URL to test case issues rust-lang@9266270ef5 Rename issue-\d+.rs tests to have meaningful names rust-lang@041e54bd92 Tweak wording of E0562 rust-lang@867cc41b5b clean up struct field suggestions rust-lang@a198aff4a4 Add `crate_name` to test so that it can be renamed rust-lang@e63d19c4dd Remove mir::LocalDecl::internal. rust-lang@f44d116e1f Fix misuses of a vs an rust-lang@a2051dd578 Optimize some `alloc_from_iter` call sites. rust-lang@816383c60d Remove the `TypedArena::alloc_from_iter` specialization. rust-lang@c373d206cd Address review nits rust-lang@90dfa24415 Only reachable traits rust-lang@afea0b4eab Fill in prose to describe the `async_fn_in_trait` lint rust-lang@28d58f6524 Bless tests rust-lang@ec79720c1e Add async_fn_in_trait lint rust-lang@999a354a81 add span to terminator rust-lang@9130484db9 create localdecl and add span to it rust-lang@06d9602d33 Only trigger refine lint on reachable traits rust-lang@702da3b89c stabilize `Option::as_`(`mut_`)`slice` rust-lang@40a52cf55c core library: Disable fpmath tests for i386 ... rust-lang@c953b6c014 doc: expand description for f32 and f64 associated constants Co-authored-by: celinval <celinval@users.noreply.github.com>

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Oct 3, 2023

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rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Oct 3, 2023

bors added a commit to rust-lang-ci/rust that referenced this pull request Oct 3, 2023

Auto merge of rust-lang#116370 - nnethercote:more-arena-stuff, r=<try>

39fc71a

More arena stuff r? `@ghost`

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rustbot removed the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Oct 3, 2023

nnethercote added 2 commits October 3, 2023 18:12

Remove the TypedArena::alloc_from_iter specialization.

816383c

It was added in rust-lang#78569. It's complicated and doesn't actually help performance. Also, add a comment explaining why the two `alloc_from_iter` functions are so different.

Optimize some alloc_from_iter call sites.

a2051dd

There's no need to collect an iterator into a `Vec`, or to call `into_iter` at the call sites.

nnethercote changed the title ~~More arena stuff~~ Remove the TypedArena::alloc_from_iter specialization. Oct 3, 2023

rustbot assigned cjgillot Oct 3, 2023

nnethercote force-pushed the more-arena-stuff branch from 2e5e49f to a2051dd Compare October 3, 2023 07:18

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nnethercote mentioned this pull request Oct 3, 2023

Make TypedArena::alloc_from_iter like DroplessArena::alloc_from_iter. #116327

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cjgillot reviewed Oct 4, 2023

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bors 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 Oct 4, 2023

bors added the merged-by-bors This PR was explicitly merged by bors. label Oct 5, 2023

bors merged commit afe67fa into rust-lang:master Oct 5, 2023
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rustbot added this to the 1.75.0 milestone Oct 5, 2023

nnethercote deleted the more-arena-stuff branch October 5, 2023 01:11

pvdrz mentioned this pull request Oct 6, 2023

Fix divergence from upstream master ferrocene/ferrocene#23

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Remove the `TypedArena::alloc_from_iter` specialization. #116370

Remove the `TypedArena::alloc_from_iter` specialization. #116370

nnethercote commented Oct 3, 2023 •

edited

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rust-timer commented Oct 5, 2023

Remove the TypedArena::alloc_from_iter specialization. #116370

Remove the TypedArena::alloc_from_iter specialization. #116370

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nnethercote commented Oct 3, 2023 • edited Loading

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Overall result: no relevant changes - no action needed

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rust-timer commented Oct 5, 2023

Overall result: no relevant changes - no action needed

Remove the `TypedArena::alloc_from_iter` specialization. #116370

Remove the `TypedArena::alloc_from_iter` specialization. #116370

nnethercote commented Oct 3, 2023 •

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