Folding revamp #97447

nnethercote · 2022-05-27T09:36:56Z

r? @ghost

nnethercote · 2022-05-27T09:37:06Z

@bors try @rust-timer queue

rust-timer · 2022-05-27T09:37:08Z

Awaiting bors try build completion.

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

bors · 2022-05-27T09:37:16Z

⌛ Trying commit 4c0dfc4f24819a7a6e29696851b8e9a937df5a17 with merge 0de273a0aaed9784c55f9056accf83bf2b496c6b...

bors · 2022-05-27T11:10:48Z

☀️ Try build successful - checks-actions
Build commit: 0de273a0aaed9784c55f9056accf83bf2b496c6b (0de273a0aaed9784c55f9056accf83bf2b496c6b)

rust-timer · 2022-05-27T11:10:50Z

Queued 0de273a0aaed9784c55f9056accf83bf2b496c6b with parent f558990, future comparison URL.

rust-timer · 2022-05-27T12:28:31Z

Finished benchmarking commit (0de273a0aaed9784c55f9056accf83bf2b496c6b): comparison url.

Instruction count

Primary benchmarks: 😿 relevant regressions found
Secondary benchmarks: mixed results

	mean¹	max	count²
Regressions 😿 (primary)	0.5%	0.9%	10
Regressions 😿 (secondary)	0.5%	0.8%	10
Improvements 🎉 (primary)	N/A	N/A	0
Improvements 🎉 (secondary)	-0.9%	-1.7%	10
All 😿🎉 (primary)	0.5%	0.9%	10

Max RSS (memory usage)

Results

Primary benchmarks: 😿 relevant regression found
Secondary benchmarks: 🎉 relevant improvements found

	mean¹	max	count²
Regressions 😿 (primary)	2.2%	2.2%	1
Regressions 😿 (secondary)	N/A	N/A	0
Improvements 🎉 (primary)	N/A	N/A	0
Improvements 🎉 (secondary)	-1.4%	-1.9%	3
All 😿🎉 (primary)	2.2%	2.2%	1

Cycles

Results

Primary benchmarks: 🎉 relevant improvements found
Secondary benchmarks: 🎉 relevant improvements found

	mean¹	max	count²
Regressions 😿 (primary)	N/A	N/A	0
Regressions 😿 (secondary)	N/A	N/A	0
Improvements 🎉 (primary)	-2.3%	-2.4%	2
Improvements 🎉 (secondary)	-3.9%	-5.5%	7
All 😿🎉 (primary)	-2.3%	-2.4%	2

If you disagree with this performance assessment, please file an issue in rust-lang/rustc-perf.

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.

Next Steps: If you can justify the regressions found in this try perf run, please indicate this with @rustbot label: +perf-regression-triaged along with sufficient written justification. If you cannot justify the regressions please fix the regressions and do another perf run. If the next run shows neutral or positive results, the label will be automatically removed.

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

the arithmetic mean of the percent change ↩ ↩² ↩³
number of relevant changes ↩ ↩² ↩³

jackh726 · 2022-05-27T15:33:10Z

I haven't read through this in deep detail, but just curious on well this aligns with (or differs from) Chalk's Fold/Visit model: https://github.com/rust-lang/chalk/blob/master/chalk-ir/src/fold.rs

nnethercote · 2022-05-31T03:14:41Z

I haven't read through this in deep detail, but just curious on well this aligns with (or differs from) Chalk's Fold/Visit model: https://github.com/rust-lang/chalk/blob/master/chalk-ir/src/fold.rs

Yes, this PR is much like the Chalk model. What Chalk calls Fold/SuperFold my commit calls TypeFoldable/TypeOfInterestFoldable. Perhaps my names are too long :)

nnethercote · 2022-06-02T06:03:45Z

r? @jackh726

Best reviewed one commit at a time.

nnethercote · 2022-06-02T06:03:56Z

@bors try @rust-timer queue

rust-timer · 2022-06-02T06:03:57Z

Awaiting bors try build completion.

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

bors · 2022-06-02T06:04:04Z

⌛ Trying commit bdfa33663f5f27d6102261e2c98aa597f28415e0 with merge 0018697d93c34b5db080c6274e26c0c202d75864...

bors · 2022-06-02T07:54:27Z

☀️ Try build successful - checks-actions
Build commit: 0018697d93c34b5db080c6274e26c0c202d75864 (0018697d93c34b5db080c6274e26c0c202d75864)

rust-timer · 2022-06-02T07:54:29Z

Queued 0018697d93c34b5db080c6274e26c0c202d75864 with parent e838059, future comparison URL.

rust-timer · 2022-06-02T09:35:52Z

Finished benchmarking commit (0018697d93c34b5db080c6274e26c0c202d75864): comparison url.

Instruction count

Primary benchmarks: mixed results
Secondary benchmarks: mixed results

	mean¹	max	count²
Regressions 😿 (primary)	0.6%	0.8%	7
Regressions 😿 (secondary)	0.9%	1.4%	10
Improvements 🎉 (primary)	-0.4%	-0.4%	4
Improvements 🎉 (secondary)	-0.9%	-1.7%	17
All 😿🎉 (primary)	0.3%	0.8%	11

Max RSS (memory usage)

Results

Primary benchmarks: no relevant changes found
Secondary benchmarks: mixed results

	mean¹	max	count²
Regressions 😿 (primary)	N/A	N/A	0
Regressions 😿 (secondary)	3.1%	4.5%	2
Improvements 🎉 (primary)	N/A	N/A	0
Improvements 🎉 (secondary)	-2.7%	-3.6%	3
All 😿🎉 (primary)	N/A	N/A	0

Cycles

Results

Primary benchmarks: no relevant changes found
Secondary benchmarks: mixed results

	mean¹	max	count²
Regressions 😿 (primary)	N/A	N/A	0
Regressions 😿 (secondary)	3.9%	3.9%	1
Improvements 🎉 (primary)	N/A	N/A	0
Improvements 🎉 (secondary)	-2.6%	-2.8%	4
All 😿🎉 (primary)	N/A	N/A	0

If you disagree with this performance assessment, please file an issue in rust-lang/rustc-perf.

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.

Next Steps: If you can justify the regressions found in this try perf run, please indicate this with @rustbot label: +perf-regression-triaged along with sufficient written justification. If you cannot justify the regressions please fix the regressions and do another perf run. If the next run shows neutral or positive results, the label will be automatically removed.

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

the arithmetic mean of the percent change ↩ ↩² ↩³
number of relevant changes ↩ ↩² ↩³

compiler/rustc_middle/src/ty/fold.rs

For most types the default impls of these methods are good enough, and `EarlyBinder` is one such type.

Because `TypeFoldable::try_fold_mir_const` exists, and even though `visit_mir_const` isn't needed right now, the consistency makes the code easier to understand.

We already have `visit_unevaluated`, so this improves consistency. Also, define `TypeFoldable for Unevaluated<'tcx, ()>` in terms of `TypeFoldable for Unevaluated<'tcx>`, which is neater.

This commit makes type folding more like the way chalk does it. Currently, `TypeFoldable` has `fold_with` and `super_fold_with` methods. - `fold_with` is the standard entry point, and defaults to calling `super_fold_with`. - `super_fold_with` does the actual work of traversing a type. - For a few types of interest (`Ty`, `Region`, etc.) `fold_with` instead calls into a `TypeFolder`, which can then call back into `super_fold_with`. With the new approach, `TypeFoldable` has `fold_with` and `TypeSuperFoldable` has `super_fold_with`. - `fold_with` is still the standard entry point, *and* it does the actual work of traversing a type, for all types except types of interest. - `super_fold_with` is only implemented for the types of interest. Benefits of the new model. - I find it easier to understand. The distinction between types of interest and other types is clearer, and `super_fold_with` doesn't exist for most types. - With the current model is easy to get confused and implement a `super_fold_with` method that should be left defaulted. (Some of the precursor commits fixed such cases.) - With the current model it's easy to call `super_fold_with` within `TypeFolder` impls where `fold_with` should be called. The new approach makes this mistake impossible, and this commit fixes a number of such cases. - It's potentially faster, because it avoids the `fold_with` -> `super_fold_with` call in all cases except types of interest. A lot of the time the compile would inline those away, but not necessarily always.

nnethercote · 2022-06-07T23:55:41Z

Thank you for the review! I have rebased.

@bors r=jackh726

bors · 2022-06-07T23:55:42Z

📌 Commit 90db033 has been approved by jackh726

bors · 2022-06-08T05:36:43Z

⌛ Testing commit 90db033 with merge 64a7aa7...

bors · 2022-06-08T08:05:41Z

☀️ Test successful - checks-actions
Approved by: jackh726
Pushing 64a7aa7 to master...

rust-timer · 2022-06-08T09:22:30Z

Finished benchmarking commit (64a7aa7): comparison url.

Instruction count

Primary benchmarks: mixed results
Secondary benchmarks: mixed results

	mean¹	max	count²
Regressions 😿 (primary)	0.5%	0.6%	6
Regressions 😿 (secondary)	0.4%	0.7%	5
Improvements 🎉 (primary)	-0.4%	-0.7%	5
Improvements 🎉 (secondary)	-0.8%	-2.1%	23
All 😿🎉 (primary)	0.1%	-0.7%	11

Max RSS (memory usage)

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

Cycles

Results

Primary benchmarks: 🎉 relevant improvement found
Secondary benchmarks: 🎉 relevant improvements found

	mean¹	max	count²
Regressions 😿 (primary)	N/A	N/A	0
Regressions 😿 (secondary)	N/A	N/A	0
Improvements 🎉 (primary)	-3.0%	-3.0%	1
Improvements 🎉 (secondary)	-4.7%	-4.9%	3
All 😿🎉 (primary)	-3.0%	-3.0%	1

If you disagree with this performance assessment, please file an issue in rust-lang/rustc-perf.

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

the arithmetic mean of the percent change ↩ ↩²
number of relevant changes ↩ ↩²

nnethercote · 2022-06-08T23:00:02Z

The perf effects are fairly small and there are more improvements than regressions.

@rustbot label: +perf-regression-triaged

Signed-off-by: Yuki Okushi <jtitor@2k36.org>

Rustup to rust-lang/rust#97447 Fixes #316 Signed-off-by: Yuki Okushi <jtitor@2k36.org>

@nnethercote

rust-lang#97447 added folding of unevaluated constants, but did not include an override of the default (fallible) operation in the blanket impl of `FallibleTypeFolder` for infallible folders. Here we provide that missing override. r? @nnethercote

…allibletypefolder, r=nnethercote `try_fold_unevaluated` for infallible folders rust-lang#97447 added folding of unevaluated constants, but did not include an override of the default (fallible) operation in the blanket impl of `FallibleTypeFolder` for infallible folders. Here we provide that missing override. r? `@nnethercote`

…allibletypefolder, r=nnethercote `try_fold_unevaluated` for infallible folders rust-lang#97447 added folding of unevaluated constants, but did not include an override of the default (fallible) operation in the blanket impl of `FallibleTypeFolder` for infallible folders. Here we provide that missing override. r? ``@nnethercote``

…allibletypefolder, r=nnethercote `try_fold_unevaluated` for infallible folders rust-lang#97447 added folding of unevaluated constants, but did not include an override of the default (fallible) operation in the blanket impl of `FallibleTypeFolder` for infallible folders. Here we provide that missing override. r? ```@nnethercote```

rustbot added T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. T-rustdoc Relevant to the rustdoc team, which will review and decide on the PR/issue. labels May 27, 2022

rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label May 27, 2022

rustbot added perf-regression Performance regression. S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-perf Status: Waiting on a perf run to be completed. labels May 27, 2022

nnethercote force-pushed the improve-folding branch 2 times, most recently from 6383df7 to bdfa336 Compare June 2, 2022 06:03

rust-highfive assigned jackh726 Jun 2, 2022

rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Jun 2, 2022

rustbot removed the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Jun 2, 2022

lcnr reviewed Jun 3, 2022

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compiler/rustc_middle/src/ty/fold.rs Show resolved Hide resolved

LegionMammal978 mentioned this pull request Jun 5, 2022

Fix stack overflows when compiling high-recursion_limit programs #93056

Closed

nnethercote added 5 commits June 8, 2022 09:22

Remove EarlyBinder::{try_fold_with,visit_with}.

ca7585a

For most types the default impls of these methods are good enough, and `EarlyBinder` is one such type.

Add TypeVisitor::visit_mir_const.

6ba2dfd

Because `TypeFoldable::try_fold_mir_const` exists, and even though `visit_mir_const` isn't needed right now, the consistency makes the code easier to understand.

Add try_fold_uenevaluted.

23880a0

We already have `visit_unevaluated`, so this improves consistency. Also, define `TypeFoldable for Unevaluated<'tcx, ()>` in terms of `TypeFoldable for Unevaluated<'tcx>`, which is neater.

Avoid some unnecessary returns.

7480b50

nnethercote force-pushed the improve-folding branch from bdfa336 to 90db033 Compare June 7, 2022 23:54

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-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jun 7, 2022

bors added the merged-by-bors This PR was explicitly merged by bors. label Jun 8, 2022

bors merged commit 64a7aa7 into rust-lang:master Jun 8, 2022

rustbot added this to the 1.63.0 milestone Jun 8, 2022

This was referenced Jun 8, 2022

Enable MIR inlining #91743

Merged

Use valtrees as the type-system representation for constant values #96591

Merged

wf-check generators #97183

Merged

nnethercote deleted the improve-folding branch June 8, 2022 22:58

rustbot added the perf-regression-triaged The performance regression has been triaged. label Jun 8, 2022

JohnTitor added a commit to JohnTitor/rust-semverver that referenced this pull request Jun 9, 2022

Rustup to rust-lang/rust#97447

aa8ccf2

Signed-off-by: Yuki Okushi <jtitor@2k36.org>

bors added a commit to rust-lang/rust-semverver that referenced this pull request Jun 9, 2022

Auto merge of #317 - JohnTitor:rustup-2022-06-09, r=JohnTitor

127312f

Rustup to rust-lang/rust#97447 Fixes #316 Signed-off-by: Yuki Okushi <jtitor@2k36.org>

eggyal mentioned this pull request Jun 20, 2022

try_fold_unevaluated for infallible folders #98306

Merged

nnethercote mentioned this pull request Jun 20, 2022

Obligation forest tweaks #97674

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Folding revamp #97447

Folding revamp #97447

nnethercote commented May 27, 2022

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nnethercote commented May 31, 2022

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nnethercote commented Jun 8, 2022

Folding revamp #97447

Folding revamp #97447

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nnethercote commented May 27, 2022

nnethercote commented May 27, 2022

rust-timer commented May 27, 2022

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Footnotes

jackh726 commented May 27, 2022

nnethercote commented May 31, 2022

nnethercote commented Jun 2, 2022

nnethercote commented Jun 2, 2022

rust-timer commented Jun 2, 2022

bors commented Jun 2, 2022

bors commented Jun 2, 2022

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Footnotes

nnethercote commented Jun 7, 2022

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Footnotes

nnethercote commented Jun 8, 2022