match lowering: eagerly simplify match pairs #120904

Nadrieril · 2024-02-11T00:45:04Z

This removes one important complication from match lowering. Before this, match pair simplification (which includes collecting bindings and type ascriptions) was intertwined with the whole match lowering algorithm.

I'm avoiding this by storing in each MatchPair the sub-MatchPairs that correspond to its subfields. This makes it possible to simplify everything (except or-patterns) in Candidate::new().

This should open up further simplifications. It will also give us proper control over the order of bindings.

r? @matthewjasper

Nadrieril · 2024-02-11T00:45:18Z

@bors try @rust-timer queue

bors · 2024-02-11T00:46:27Z

⌛ Trying commit 45ef29c with merge d39daec...

…e-repr, r=<try> match lowering: eagerly simplify match pairs This removes one important complication from match lowering. Before this, match pair simplification (which includes collecting bindings and type ascriptions) was intertwined with the whole match lowering algorithm. I'm avoiding this by storing in each `MatchPair` the sub-`MatchPair`s that correspond to its subfields. This makes it possible to simplify everything (except or-patterns) in `Candidate::new()`. This should open up further simplifications. It will also give us proper control over the order of bindings. r? `@matthewjasper`

bors · 2024-02-11T02:13:38Z

☀️ Try build successful - checks-actions
Build commit: d39daec (d39daecd2270ce85a3888cadd36b654a8f380a06)

rust-timer · 2024-02-11T03:31:23Z

Finished benchmarking commit (d39daec): comparison URL.

Overall result: ✅ improvements - 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 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
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-2.3%	[-3.1%, -1.8%]	6
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-2.3%	[-3.1%, -1.8%]	6

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)	3.6%	[3.6%, 3.6%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.3%	[-2.3%, -2.2%]	3
All ❌✅ (primary)	-	-	0

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)	-2.4%	[-3.0%, -2.0%]	5
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-2.4%	[-3.0%, -2.0%]	5

Binary size

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)	0.2%	[0.1%, 0.2%]	2
Regressions ❌ (secondary)	0.1%	[0.1%, 0.1%]	1
Improvements ✅ (primary)	-0.0%	[-0.1%, -0.0%]	2
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.1%	[-0.1%, 0.2%]	4

Bootstrap: 666.058s -> 664.547s (-0.23%)
Artifact size: 308.32 MiB -> 308.30 MiB (-0.01%)

matthewjasper

Couple of style/comment nits.

matthewjasper · 2024-02-19T14:33:00Z

compiler/rustc_mir_build/src/build/matches/simplify.rs

@@ -142,31 +126,31 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
    /// candidate.
    fn simplify_match_pair<'pat>(


Comment should be updated for change in parameters

matthewjasper · 2024-02-19T16:06:14Z

compiler/rustc_mir_build/src/build/matches/test.rs

@@ -589,22 +589,17 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
        // away.)
        let (match_pair_index, match_pair) =
            candidate.match_pairs.iter().enumerate().find(|&(_, mp)| mp.place == *test_place)?;
+        let mut fully_matched = false;


I would prefer this to be let fully_matched; and have every branch assign true or false.

Ooh yeah, in another branch I in fact forgot to set it once, and the resulting infinite loop crashed my laptop x) Good shout.

Because I'm about to make MatchPair recursive, which I can't do with SmallVec, and I need to share code between the two.

Because we will soon need to apply it to match pairs that aren't directly in a candidate.

Nadrieril · 2024-02-19T20:35:37Z

Thanks for the review!

@rustbot ready

matthewjasper · 2024-02-20T10:09:22Z

@bors r+

bors · 2024-02-20T10:09:24Z

📌 Commit 328c776 has been approved by matthewjasper

It is now in the queue for this repository.

bors · 2024-02-20T18:34:19Z

⌛ Testing commit 328c776 with merge 1aa6816...

…e-repr, r=matthewjasper match lowering: eagerly simplify match pairs This removes one important complication from match lowering. Before this, match pair simplification (which includes collecting bindings and type ascriptions) was intertwined with the whole match lowering algorithm. I'm avoiding this by storing in each `MatchPair` the sub-`MatchPair`s that correspond to its subfields. This makes it possible to simplify everything (except or-patterns) in `Candidate::new()`. This should open up further simplifications. It will also give us proper control over the order of bindings. r? `@matthewjasper`

bors · 2024-02-20T22:49:19Z

💥 Test timed out

rust-log-analyzer · 2024-02-20T22:55:45Z

A job failed! Check out the build log: (web) (plain)

Click to see the possible cause of the failure (guessed by this bot)

Nadrieril · 2024-02-20T23:14:18Z

I can't tell which is the test that timed out or if this has anything to do with this PR.

@bors retry

bors · 2024-02-21T01:11:37Z

⌛ Testing commit 328c776 with merge 4e65074...

bors · 2024-02-21T03:10:18Z

☀️ Test successful - checks-actions
Approved by: matthewjasper
Pushing 4e65074 to master...

rust-timer · 2024-02-21T04:49:34Z

Finished benchmarking commit (4e65074): 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
Regressions ❌ (secondary)	0.2%	[0.2%, 0.2%]	3
Improvements ✅ (primary)	-2.0%	[-3.1%, -0.2%]	7
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-2.0%	[-3.1%, -0.2%]	7

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)	-3.4%	[-3.6%, -3.3%]	2
Improvements ✅ (secondary)	-2.6%	[-2.6%, -2.6%]	1
All ❌✅ (primary)	-3.4%	[-3.6%, -3.3%]	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)	-2.4%	[-3.0%, -1.6%]	5
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-2.4%	[-3.0%, -1.6%]	5

Binary size

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)	0.1%	[0.0%, 0.2%]	3
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.1%	[0.0%, 0.2%]	3

Bootstrap: 639.89s -> 640.784s (0.14%)
Artifact size: 308.62 MiB -> 308.61 MiB (-0.00%)

… r=matthewjasper match lowering: Introduce a `TestCase` enum to replace most matching on `PatKind` Introduces `TestCase` that represents the specific outcome of a test. It complements `TestKind` which represents a test. In `MatchPair::new()` we select the appropriate `TestCase` for the pattern, and after that we almost never have to inspect the pattern directly during match lowering. Together with rust-lang#120904, this makes `MatchPair` into a standalone abstraction that hides the details of `thir::Pat`. This will become even truer in the next PR where I make `TestCase` handle or patterns. This opens the door to a lot of future simplifications. r? `@matthewjasper`

Rollup merge of rust-lang#121393 - Nadrieril:match-lowering-testcase, r=matthewjasper match lowering: Introduce a `TestCase` enum to replace most matching on `PatKind` Introduces `TestCase` that represents the specific outcome of a test. It complements `TestKind` which represents a test. In `MatchPair::new()` we select the appropriate `TestCase` for the pattern, and after that we almost never have to inspect the pattern directly during match lowering. Together with rust-lang#120904, this makes `MatchPair` into a standalone abstraction that hides the details of `thir::Pat`. This will become even truer in the next PR where I make `TestCase` handle or patterns. This opens the door to a lot of future simplifications. r? `@matthewjasper`

rylev · 2024-02-27T13:15:46Z

Improvements far outweigh the regressions so I don't think this needs further investigation.

@rustbot label: +perf-regression-triaged

In rust-lang#120904, `MatchPair` became able to store other match pairs as children, forming a tree. That has made the old name confusing, so this patch renames the type to `MatchPairTree`.

match lowering: Rename `MatchPair` to `MatchPairTree` In rust-lang#120904, `MatchPair` became able to store other match pairs as children, forming a tree. That has made the old name confusing, so this patch renames the type to `MatchPairTree`. This PR also includes a patch renaming the `test` method to `pick_test_for_match_pair`, since it would conflict with the main change. r? `@Nadrieril`

Rollup merge of rust-lang#127858 - Zalathar:pair-tree, r=Nadrieril match lowering: Rename `MatchPair` to `MatchPairTree` In rust-lang#120904, `MatchPair` became able to store other match pairs as children, forming a tree. That has made the old name confusing, so this patch renames the type to `MatchPairTree`. This PR also includes a patch renaming the `test` method to `pick_test_for_match_pair`, since it would conflict with the main change. r? `@Nadrieril`

rustbot assigned matthewjasper Feb 11, 2024

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Nadrieril force-pushed the match-lowering-intermediate-repr branch 2 times, most recently from 25247a7 to d33fbc9 Compare February 14, 2024 21:50

matthewjasper reviewed Feb 19, 2024

View reviewed changes

Nadrieril added 8 commits February 19, 2024 21:28

Switch to Vec of MatchPairs

48b83e8

Because I'm about to make MatchPair recursive, which I can't do with SmallVec, and I need to share code between the two.

Move Or test outside of simplify_candidate

bafad5a

Make simplify_candidate more general

e86c822

Because we will soon need to apply it to match pairs that aren't directly in a candidate.

Don't repeatedly simplify already-simplified match pairs

308b482

Eagerly simplify match pairs

d936ab6

Compute subpairs when creating match pair

1507276

Don't default fully_matched to false to avoid mistakes

0ca1d22

Update comments

328c776

Nadrieril force-pushed the match-lowering-intermediate-repr branch from d33fbc9 to 328c776 Compare February 19, 2024 20:36

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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 Feb 20, 2024

bors added the S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. label Feb 20, 2024

bors added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Feb 20, 2024

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 Feb 20, 2024

bors added the merged-by-bors This PR was explicitly merged by bors. label Feb 21, 2024

bors merged commit 4e65074 into rust-lang:master Feb 21, 2024
12 checks passed

rustbot added this to the 1.78.0 milestone Feb 21, 2024

rustbot added the perf-regression Performance regression. label Feb 21, 2024

Nadrieril deleted the match-lowering-intermediate-repr branch February 21, 2024 10:19

Nadrieril mentioned this pull request Feb 21, 2024

match lowering: Introduce a TestCase enum to replace most matching on PatKind #121393

Merged

rustbot added the perf-regression-triaged The performance regression has been triaged. label Feb 27, 2024

Zalathar mentioned this pull request Jul 17, 2024

match lowering: Rename MatchPair to MatchPairTree #127858

Merged

matthiaskrgr mentioned this pull request Oct 11, 2024

ICE: WellFormed .. has escaping bound vars, so it cannot be wrapped in a dummy binder. #131535

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matthiaskrgr mentioned this pull request Nov 21, 2024

ICE: unexpected 'SelfCtor' in pattern, expected identifier #133272

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match lowering: eagerly simplify match pairs #120904

match lowering: eagerly simplify match pairs #120904

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rylev commented Feb 27, 2024

		@@ -142,31 +126,31 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
		/// candidate.
		fn simplify_match_pair<'pat>(

match lowering: eagerly simplify match pairs #120904

match lowering: eagerly simplify match pairs #120904

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Overall result: ✅ improvements - no action needed

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Overall result: ❌✅ regressions and improvements - ACTION NEEDED

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