split `NormalizesTo` out of `Projection` 3 #118725

lcnr · 2023-12-07T22:45:06Z

third attempt at #112658. Rebasing #116262 is very annoying, so I am doing it again from scratch. We should now be able to merge it without regressing anything as we handle occurs check failures involving aliases correctly since #117088.

see https://hackmd.io/ktEL8knTSYmtdfrMMnA-Hg

fixes rust-lang/trait-system-refactor-initiative#1

r? @compiler-errors

rustbot · 2023-12-07T22:45:15Z

Some changes occurred to the core trait solver

cc @rust-lang/initiative-trait-system-refactor

lcnr · 2023-12-08T00:36:04Z

tests/ui/traits/new-solver/generalize/generalize-proj-new-universe-index-2.rs

@@ -1,5 +1,7 @@
 // compile-flags: -Ztrait-solver=next
 // known-bug: trait-system-refactor-initiative#60
+// dont-check-failure-status
+// dont-check-compiler-stderr


This test now ICEs, but given that it's already buggy I don't want this to block merging this PR. Will look at it separately.

would be fixed by actually reporting errors in writeback if normalization fails. Unfortunately that ICEs because regions have already been resolved. Will do this in a separate PR, temp diff 193abb3

BoxyUwU · 2023-12-08T00:46:35Z

compiler/rustc_infer/src/infer/combine.rs

+                match a_ty.kind() {
+                    &ty::Alias(ty::AliasKind::Projection, data) => {
+                        // FIXME: This does not handle subtyping correctly, we should switch to
+                        // alias-relate in the new solver and could instead create a new inference


we do use alias relate in the new solver like 2 lines above. is this still relevant?

BoxyUwU · 2023-12-08T01:03:17Z

r? @BoxyUwU

BoxyUwU · 2023-12-08T01:20:22Z

@bors r+ rollup=never p=1 (i dont trust adding new predicate kinds to not be conflicty and also i mgiht be perf)

bors · 2023-12-08T01:20:25Z

📌 Commit ac50f4b has been approved by BoxyUwU

It is now in the queue for this repository.

bors · 2023-12-08T02:28:14Z

⌛ Testing commit ac50f4b with merge 21982a4...

bors · 2023-12-08T05:10:03Z

☀️ Test successful - checks-actions
Approved by: BoxyUwU
Pushing 21982a4 to master...

rust-timer · 2023-12-08T06:32:01Z

Finished benchmarking commit (21982a4): comparison URL.

Overall result: ❌✅ regressions and improvements - ACTION NEEDED

Next Steps: If you can justify the regressions found in this perf run, please indicate this with @rustbot label: +perf-regression-triaged along with sufficient written justification. If you cannot justify the regressions please open an issue or create a new PR that fixes the regressions, add a comment linking to the newly created issue or PR, and then add the perf-regression-triaged label to this PR.

@rustbot label: +perf-regression
cc @rust-lang/wg-compiler-performance

Instruction count

This is a highly reliable metric that was used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	0.4%	[0.2%, 0.9%]	17
Regressions ❌ (secondary)	0.3%	[0.2%, 0.3%]	3
Improvements ✅ (primary)	-2.6%	[-2.6%, -2.6%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.3%	[-2.6%, 0.9%]	18

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)	0.6%	[0.6%, 0.6%]	1
Regressions ❌ (secondary)	3.2%	[3.2%, 3.2%]	2
Improvements ✅ (primary)	-0.4%	[-0.4%, -0.4%]	1
Improvements ✅ (secondary)	-2.9%	[-2.9%, -2.9%]	1
All ❌✅ (primary)	0.1%	[-0.4%, 0.6%]	2

Cycles

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)	-2.7%	[-2.7%, -2.7%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-2.7%	[-2.7%, -2.7%]	1

Binary size

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

Bootstrap: 675.561s -> 673.716s (-0.27%)
Artifact size: 314.00 MiB -> 314.08 MiB (0.03%)

BoxyUwU · 2023-12-08T06:48:28Z

probably caused by adding the new PredicateKind. looks small and we need this for new solver so 🤷‍♀️

perf: experiment with only non-functional changes from rust-lang#118725 cc rust-lang#118735 r? `@ghost`

aliemjay · 2023-12-08T12:58:11Z

callgrind diff of bors builds:

Ir1	Called1	Ir2	Called2	function
7,225,289,206	--	+26,998,798	--	Total for serde-1.0.136-Check-full
104,905,987	184,425	+7,130,548	+0	`<rustc_trait_selection::traits::fulfill::FulfillmentContext as rustc_infer::traits::engine::TraitEngine>::register_predicate_obligation:???`
191,337,918	137,023	+5,772,202	+0	`<rustc_middle::ty::ParamEnv as rustc_type_ir::fold::TypeFoldable<rustc_middle::ty::context::TyCtxt>>::try_fold_with::<rustc_infer::infer::canonical::canonicalizer::Canonicalizer>:???`
177,171,243	1,337,430	+5,230,173	+0	`<rustc_middle::ty::context::CtxtInterners>::intern_predicate:???`
39,833,350	243,002	+1,776,212	+0	`<rustc_middle::ty::Clause as rustc_type_ir::fold::TypeFoldable<rustc_middle::ty::context::TyCtxt>>::try_fold_with::<rustc_middle::ty::generic_args::ArgFolder>:???`

The regressed crates are exactly the ones that benefit the most from #117749 where predicate interning and folding is very hot. I don't think there is much that can be done to mitigate the impact. Each function runtime has increased by few instructions as expected but that's enough to make a difference because of how much hot they are.

@lcnr consider reviewing #117749 to repent for your sin :)

refactor infer var storage cleanup the code, discovered while working on rust-lang#118725

refactor writeback: emit normalization errors with new solver implements rust-lang#118725 (comment) r? `@compiler-errors` `@BoxyUwU` whoever comes first n stuff

…rrors refactor infer var storage cleanup the code, discovered while working on rust-lang#118725

…rors refactor writeback: emit normalization errors with new solver implements rust-lang#118725 (comment) r? `@compiler-errors` `@BoxyUwU` whoever comes first n stuff

…, r=lcnr Unconditionally register alias-relate in projection goal Follow-up to rust-lang#118725, which subtly broke closure signature inference on combinators like `Result::map` which I noticed in syn. Essentially, instead of using `eq` which will eagerly infer `?1 := <?2 as Trait>::Assoc`, we can directly emit an alias-relate goal, which will stay ambiguous for as long as `?2` is ambiguous. This also more closely models the conceptual framing that projects-to acts like an alias-relate when solving, and like a normalizes-to when in a param env. r? lcnr

Rollup merge of rust-lang#118914 - compiler-errors:eager-alias-relate, r=lcnr Unconditionally register alias-relate in projection goal Follow-up to rust-lang#118725, which subtly broke closure signature inference on combinators like `Result::map` which I noticed in syn. Essentially, instead of using `eq` which will eagerly infer `?1 := <?2 as Trait>::Assoc`, we can directly emit an alias-relate goal, which will stay ambiguous for as long as `?2` is ambiguous. This also more closely models the conceptual framing that projects-to acts like an alias-relate when solving, and like a normalizes-to when in a param env. r? lcnr

lcnr added 2 commits December 7, 2023 16:13

avoid instantiating infer vars with infer

40aa9f4

add unused NormalizesTo predicate

3978f54

rustbot assigned compiler-errors Dec 7, 2023

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. WG-trait-system-refactor The Rustc Trait System Refactor Initiative (-Znext-solver) labels Dec 7, 2023

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lcnr mentioned this pull request Dec 7, 2023

split NormalizesTo out of Projection 2 #116262

Closed

implement and use NormalizesTo

ffb4c08

lcnr force-pushed the normalizes-to-projection-split-3 branch from 5c0809e to ffb4c08 Compare December 8, 2023 00:31

add regression tests

1490c58

lcnr commented Dec 8, 2023

View reviewed changes

BoxyUwU approved these changes Dec 8, 2023

View reviewed changes

rustbot assigned BoxyUwU and unassigned compiler-errors Dec 8, 2023

update fixme

ac50f4b

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 Dec 8, 2023

bors added the merged-by-bors This PR was explicitly merged by bors. label Dec 8, 2023

bors merged commit 21982a4 into rust-lang:master Dec 8, 2023
12 checks passed

rustbot added this to the 1.76.0 milestone Dec 8, 2023

bors mentioned this pull request Dec 8, 2023

Introduce support for async gen blocks #118420

Merged

rustbot added the perf-regression Performance regression. label Dec 8, 2023

BoxyUwU added the perf-regression-triaged The performance regression has been triaged. label Dec 8, 2023

lcnr deleted the normalizes-to-projection-split-3 branch December 8, 2023 06:59

bors added a commit to rust-lang-ci/rust that referenced this pull request Dec 8, 2023

Auto merge of rust-lang#118735 - lcnr:predicate-split, r=<try>

c502f84

perf: experiment with only non-functional changes from rust-lang#118725 cc rust-lang#118735 r? `@ghost`

aliemjay mentioned this pull request Dec 8, 2023

perf: experiment with only non-functional changes from #118725 #118735

Closed

lcnr mentioned this pull request Dec 8, 2023

refactor infer var storage #118742

Merged

bors added a commit to rust-lang-ci/rust that referenced this pull request Dec 8, 2023

Auto merge of rust-lang#118742 - lcnr:infer-var-cleanup, r=<try>

bc279f6

refactor infer var storage cleanup the code, discovered while working on rust-lang#118725

lcnr mentioned this pull request Dec 8, 2023

refactor writeback: emit normalization errors with new solver #118751

Merged

bors added a commit to rust-lang-ci/rust that referenced this pull request Dec 12, 2023

Auto merge of rust-lang#118742 - lcnr:infer-var-cleanup, r=compiler-e…

5f5d248

…rrors refactor infer var storage cleanup the code, discovered while working on rust-lang#118725

compiler-errors mentioned this pull request Dec 13, 2023

Unconditionally register alias-relate in projection goal #118914

Merged

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split `NormalizesTo` out of `Projection` 3 #118725

split `NormalizesTo` out of `Projection` 3 #118725

lcnr commented Dec 7, 2023 •

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aliemjay commented Dec 8, 2023

split NormalizesTo out of Projection 3 #118725

split NormalizesTo out of Projection 3 #118725

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rust-timer commented Dec 8, 2023

Overall result: ❌✅ regressions and improvements - ACTION NEEDED

Instruction count

Max RSS (memory usage)

Cycles

Binary size

BoxyUwU commented Dec 8, 2023

aliemjay commented Dec 8, 2023

split `NormalizesTo` out of `Projection` 3 #118725

split `NormalizesTo` out of `Projection` 3 #118725

lcnr commented Dec 7, 2023 •

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