Preserve most sub-obligations in the projection cache #85868

Aaron1011 · 2021-05-31T18:23:16Z

When we evaluate a projection predicate, we may produce sub-obligations. During trait evaluation, evaluating these sub-obligations might cause us to produce EvaluatedToOkModuloRegions.

When we cache the result of projection in our projection cache, we try to throw away some of the sub-obligations, so that we don't need to re-evaluate/process them the next time we need to perform this particular projection. However, we may end up throwing away predicates that will (recursively) evaluate to EvaluatedToOkModuloRegions. If we do, then the result of evaluating a predicate will depend on the state of the predicate cache - this is global untracked state, which interacts badly with incremental compilation.

To fix this, we now only discard global predicates that evaluate to EvaluatedToOk. This ensures that any predicates that (may) evaluate to EvaluatedToOkModuloRegions are kept in the cache, and influence the results of any queries which perform this projection.

rust-highfive · 2021-05-31T18:23:18Z

r? @matthewjasper

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Aaron1011 · 2021-05-31T18:23:26Z

@bors try @rust-timer queue

rust-timer · 2021-05-31T18:23:27Z

Awaiting bors try build completion.

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

bors · 2021-05-31T18:23:34Z

⌛ Trying commit a3a287b0bfe095e1fd9bd4292a0e94f738a94cce with merge fa0462d22926332548181c1cd602c85dbb20fec8...

bors · 2021-05-31T19:09:34Z

☀️ Try build successful - checks-actions
Build commit: fa0462d22926332548181c1cd602c85dbb20fec8 (fa0462d22926332548181c1cd602c85dbb20fec8)

rust-timer · 2021-05-31T19:09:36Z

Queued fa0462d22926332548181c1cd602c85dbb20fec8 with parent 6a3dce9, future comparison URL.

rust-timer · 2021-05-31T22:50:03Z

Finished benchmarking try commit (fa0462d22926332548181c1cd602c85dbb20fec8): comparison url.

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. Please note that if the perf results are neutral, you should likely undo the rollup=never given below by specifying rollup- to bors.

Importantly, though, if the results of this run are non-neutral do not roll this PR up -- it will mask other regressions or improvements in the roll up.

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

Aaron1011 · 2021-06-25T01:30:31Z

@bors try @rust-timer queue

rust-timer · 2021-06-25T01:30:32Z

Awaiting bors try build completion.

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

bors · 2021-06-25T01:30:41Z

⌛ Trying commit a3a287b0bfe095e1fd9bd4292a0e94f738a94cce with merge d246c813ecc8de89cc5a05b9479dac8195a3e251...

bors · 2021-06-25T02:20:51Z

☀️ Try build successful - checks-actions
Build commit: d246c813ecc8de89cc5a05b9479dac8195a3e251 (d246c813ecc8de89cc5a05b9479dac8195a3e251)

rust-timer · 2021-06-25T02:20:52Z

Queued d246c813ecc8de89cc5a05b9479dac8195a3e251 with parent d4e7cb3, future comparison URL.

rust-timer · 2021-06-25T05:24:02Z

Finished benchmarking try commit (d246c813ecc8de89cc5a05b9479dac8195a3e251): comparison url.

Summary: This change led to significant regressions 😿 in compiler performance.

Very large regression in instruction counts (up to 21.4% on full builds of deeply-nested-check)

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. Please note that if the perf results are neutral, you should likely undo the rollup=never given below by specifying rollup- to bors.

Importantly, though, if the results of this run are non-neutral do not roll this PR up -- it will mask other regressions or improvements in the roll up.

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

rustbot · 2021-06-25T05:24:04Z

Error: Label perf-regression can only be set by Rust team members

Please let @rust-lang/release know if you're having trouble with this bot.

Aaron1011 · 2021-07-12T21:44:38Z

@bors try @rust-timer queue

rust-timer · 2021-07-12T21:44:39Z

Awaiting bors try build completion.

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

bors · 2021-07-12T21:44:47Z

⌛ Trying commit fbfe5baaf5d5faff7450209c02a699ad25948230 with merge 7d3788b67103a424bf6612495afedb80c4fe8b10...

bors · 2021-09-02T21:27:03Z

⌛ Testing commit 611191f with merge 371f3cd...

bors · 2021-09-02T23:56:32Z

☀️ Test successful - checks-actions
Approved by: jackh726
Pushing 371f3cd to master...

pnkfelix · 2021-09-08T15:06:35Z

@nikomatsakis: This PR is now ready for review.

This performance is worse than the two other approaches (#86896 and #86871), but this is less hacky, and more clearly correct.

As expected, this was flagged as causing mixed performance changes in instruction counts during weekly performance triage. Since these changes in performance were anticipating and discussed above, I'm marking as already-triaged.

Update: whoops, it was already marked accordingly. Sorry for the noise!

apiraino · 2021-09-09T15:10:49Z

It's already in current beta (Zulip comment)

@rustbot label -beta-nominated

jackh726 · 2021-09-09T15:13:14Z

Do we want to nominate for stable? How concerned are we about this incremental issue? @rust-lang/compiler

@lqd

Adds the minimial repro test case from rust-lang#85360. The fix for rust-lang#85360 was supposed to be rust-lang#85868 however the repro was resolved in the 2021-07-05 nightly while rust-lang#85360 didn't land until 2021-09-03. The reason for that is d34a3a4 **also** resolves that issue. To test if rust-lang#85868 actually fixes rust-lang#85360, I reverted d34a3a4 and found that rust-lang#85868 does indeed resolve rust-lang#85360. With that question resolved, add a test case to our incremental test suite for the original Ok(EvaluatedToOkModuloRegions) ICE. Thanks to @lqd for helping track this down!

Add test for evaluate_obligation: Ok(EvaluatedToOkModuloRegions) ICE Adds the minimial repro test case from rust-lang#85360. The fix for rust-lang#85360 was supposed to be rust-lang#85868 however the repro was resolved in the 2021-07-05 nightly while rust-lang#85868 didn't land until 2021-09-03. The reason for that is d34a3a4 **also** resolves that issue. To test if rust-lang#85868 actually fixes rust-lang#85360, I reverted d34a3a4 and found that rust-lang#85868 does indeed resolve rust-lang#85360. With that question resolved, add a test case to our incremental test suite for the original Ok(EvaluatedToOkModuloRegions) ICE. Thanks to `@lqd` for helping track this down!

Add test for evaluate_obligation: Ok(EvaluatedToOkModuloRegions) ICE Adds the minimial repro test case from rust-lang#85360. The fix for rust-lang#85360 was supposed to be rust-lang#85868 however the repro was resolved in the 2021-07-05 nightly while rust-lang#85868 didn't land until 2021-09-03. The reason for that is d34a3a4 **also** resolves that issue. To test if rust-lang#85868 actually fixes rust-lang#85360, I reverted d34a3a4 and found that rust-lang#85868 does indeed resolve rust-lang#85360. With that question resolved, add a test case to our incremental test suite for the original Ok(EvaluatedToOkModuloRegions) ICE. Thanks to ``@lqd`` for helping track this down!

Add test for evaluate_obligation: Ok(EvaluatedToOkModuloRegions) ICE Adds the minimial repro test case from rust-lang#85360. The fix for rust-lang#85360 was supposed to be rust-lang#85868 however the repro was resolved in the 2021-07-05 nightly while rust-lang#85868 didn't land until 2021-09-03. The reason for that is d34a3a4 **also** resolves that issue. To test if rust-lang#85868 actually fixes rust-lang#85360, I reverted d34a3a4 and found that rust-lang#85868 does indeed resolve rust-lang#85360. With that question resolved, add a test case to our incremental test suite for the original Ok(EvaluatedToOkModuloRegions) ICE. Thanks to ```@lqd``` for helping track this down!

Add test for evaluate_obligation: Ok(EvaluatedToOkModuloRegions) ICE Adds the minimial repro test case from rust-lang#85360. The fix for rust-lang#85360 was supposed to be rust-lang#85868 however the repro was resolved in the 2021-07-05 nightly while rust-lang#85868 didn't land until 2021-09-03. The reason for that is d34a3a4 **also** resolves that issue. To test if rust-lang#85868 actually fixes rust-lang#85360, I reverted d34a3a4 and found that rust-lang#85868 does indeed resolve rust-lang#85360. With that question resolved, add a test case to our incremental test suite for the original Ok(EvaluatedToOkModuloRegions) ICE. Thanks to ````@lqd```` for helping track this down!

@lqd

Adds the minimial repro test case from rust-lang#85360. The fix for rust-lang#85360 was supposed to be rust-lang#85868 however the repro was resolved in the 2021-07-05 nightly while rust-lang#85360 didn't land until 2021-09-03. The reason for that is d34a3a4 **also** resolves that issue. To test if rust-lang#85868 actually fixes rust-lang#85360, I reverted d34a3a4 and found that rust-lang#85868 does indeed resolve rust-lang#85360. With that question resolved, add a test case to our incremental test suite for the original Ok(EvaluatedToOkModuloRegions) ICE. Thanks to @lqd for helping track this down!

rust-highfive assigned matthewjasper May 31, 2021

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label May 31, 2021

rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label May 31, 2021

rustbot removed the S-waiting-on-perf Status: Waiting on a perf run to be completed. label May 31, 2021

Aaron1011 mentioned this pull request Jun 3, 2021

Incremental compilation error with evaluate_obligation: Ok(EvaluatedToOkModuloRegions) #85360

Closed

MOZGIII mentioned this pull request Jun 14, 2021

Cache builds in CI humanode-network/humanode#20

Merged

2 tasks

rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Jun 25, 2021

JohnTitor removed the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Jun 28, 2021

Aaron1011 force-pushed the projection-cache branch from a3a287b to fbfe5ba Compare July 12, 2021 21:44

rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Jul 12, 2021

bors added the S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. label Sep 2, 2021

camelid mentioned this pull request Sep 2, 2021

[WIP] Use all projection sub-obligations during trait evaluation #86896

Closed

bors added the merged-by-bors This PR was explicitly merged by bors. label Sep 2, 2021

bors merged commit 371f3cd into rust-lang:master Sep 2, 2021

rustbot added this to the 1.56.0 milestone Sep 2, 2021

This was referenced Sep 4, 2021

ICE with recursive type using GAT. #87750

Closed

ICE when getting the size of a struct containing itself in an odd way #82830

Closed

jackh726 mentioned this pull request Sep 9, 2021

Try to evalate obligation in fulfillment when we have no inference vars #86748

Closed

rustbot removed the beta-nominated Nominated for backporting to the compiler in the beta channel. label Sep 9, 2021

Aaron1011 mentioned this pull request Sep 15, 2021

regression: Copy no longer implemented #88969

Closed

jackh726 mentioned this pull request Sep 16, 2021

Remove concept of 'completion' from the projection cache #88945

Merged

apiraino mentioned this pull request Oct 4, 2021

Where bounds with associated types equality cause overflow. #89503

Open

nayato mentioned this pull request Oct 13, 2021

Re-introduce concept of projection cache 'completion' #89831

Merged

camelid mentioned this pull request Nov 6, 2021

Regression in 1.56.0 - Trait bound not satisfied error even though the impl exists #90662

Closed

wesleywiser mentioned this pull request Nov 20, 2021

Add test for evaluate_obligation: Ok(EvaluatedToOkModuloRegions) ICE #91065

Merged

hkratz mentioned this pull request Dec 15, 2021

Exponential slowdown in catching an overflow error. #91949

Closed

Aaron1011 mentioned this pull request Feb 18, 2022

ICE index OOB in 1.59.0-beta.8 🚨 #94124

Closed

Preserve most sub-obligations in the projection cache #85868

Preserve most sub-obligations in the projection cache #85868

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