Optimisation: avoid emitting verify bounds that always hold#152579
Open
amandasystems wants to merge 2 commits intorust-lang:mainfrom
Open
Optimisation: avoid emitting verify bounds that always hold#152579amandasystems wants to merge 2 commits intorust-lang:mainfrom
amandasystems wants to merge 2 commits intorust-lang:mainfrom
Conversation
… hold This makes more sense than you'd imagine since empty `All` bounds which always hold is relatively common.
d55cf4c to
6b612a0
Compare
lcnr
reviewed
Feb 13, 2026
compiler/rustc_borrowck/src/type_check/constraint_conversion.rs
Outdated
Show resolved
Hide resolved
lcnr
reviewed
Feb 26, 2026
|
|
||
| // If this bound is always satisfied, a complex bound should never have been | ||
| // constructed and we should have gotten [[`VerifyBound::always_satisfied`]] | ||
| debug_assert!( |
Contributor
|
@bors try @rust-timer queue |
This comment has been minimized.
This comment has been minimized.
This comment has been minimized.
This comment has been minimized.
rust-bors bot
pushed a commit
that referenced
this pull request
Feb 26, 2026
Optimisation: avoid emitting verify bounds that always hold
Contributor
This comment has been minimized.
This comment has been minimized.
Collaborator
|
Finished benchmarking commit (158e3b6): comparison URL. Overall result: ✅ improvements - no action neededBenchmarking this pull request means it may be perf-sensitive – we'll automatically label it not fit for rolling up. You can override this, but we strongly advise not to, due to possible changes in compiler perf. @bors rollup=never Instruction countOur most reliable metric. Used to determine the overall result above. However, even this metric can be noisy.
Max RSS (memory usage)Results (primary 3.0%)A less reliable metric. May be of interest, but not used to determine the overall result above.
CyclesResults (secondary 2.4%)A less reliable metric. May be of interest, but not used to determine the overall result above.
Binary sizeThis benchmark run did not return any relevant results for this metric. Bootstrap: 480.119s -> 484.722s (0.96%) |
21 tasks
lcnr
reviewed
Mar 2, 2026
| this.append(&mut that); | ||
| VerifyBound::AnyBound(this) | ||
| } | ||
| // FIXME: This can still nest arbitrarily. |
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
4 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
This PR normalises verify bounds that always hold and uses that logic to cheaply detect that case and never emit them.
This leaves a ton of tripwire assertions around that will activate if these assumptions are violated.
VerifyBound::or()is now also short-circuiting and flattens immediately nested Any bounds. Note that the short-circuiting means information may be lost if both bounds are failing and we want to keep both failing bounds.r? @lcnr