`RegionValues`: disable unnecessary range check by amandasystems · Pull Request #158026 · rust-lang/rust

amandasystems · 2026-06-17T12:46:31Z

Currently, when adding liveness points to region values in the RegionValues struct, the locations of the points are checked for ranges. This is unnecessarily cautious because they always are in range by construction. The docstring for the method used in the checks suggests that it was designed for underlying bit sets that currently aren't used for this.

This adds documentation (including debug assertions) to make this clearer and removes the checks, which should have a strictly positive impact on performance.

rustbot · 2026-06-17T12:46:36Z

r? @petrochenkov

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petrochenkov · 2026-06-18T12:24:03Z

This looks reasonable, but I'm not familiar with this code, feel free to reassign if necessary.
@rustbot author

rustbot · 2026-06-18T12:24:09Z

Reminder, once the PR becomes ready for a review, use @rustbot ready.

Currently, when adding liveness points to region values in the `RegionValues` struct, the locations of the points are checked for ranges. This is unnecessarily cautious because they always are in range by construction. This adds documentation (including debug assertions) to make this clearer and removes the checks, which should have a strictly positive impact on performance.

amandasystems · 2026-06-18T14:20:40Z

That should be all of the comments!

@rustbot ready

rust-log-analyzer · 2026-06-18T14:23:28Z

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

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

  IMAGE: x86_64-gnu-gcc
##[endgroup]
    Updating crates.io index
error: failed to get `adler2` as a dependency of package `miniz_oxide v0.8.8`
    ... which satisfies dependency `miniz_oxide = "^0.8.5"` of package `flate2 v1.1.9`
    ... which satisfies dependency `flate2 = "^1.1.9"` of package `citool v0.1.0 (/home/runner/work/rust/rust/src/ci/citool)`

Caused by:
  failed to load source for dependency `adler2`

Caused by:
  unable to update registry `crates-io`

Caused by:
  download of ad/le/adler2 failed

Caused by:
  curl failed

Caused by:

petrochenkov · 2026-06-18T15:40:18Z

The CI failure is spurious.
@bors r+

rust-bors · 2026-06-18T15:40:24Z

📌 Commit dbf6d75 has been approved by petrochenkov

It is now in the queue for this repository.

…no-range-check, r=petrochenkov `RegionValues`: disable unnecessary range check Currently, when adding liveness points to region values in the `RegionValues` struct, the locations of the points are checked for ranges. This is unnecessarily cautious because they always are in range by construction. The docstring for the method used in the checks suggests that it was designed for underlying bit sets that currently aren't used for this. This adds documentation (including debug assertions) to make this clearer and removes the checks, which should have a strictly positive impact on performance.

…uwer Rollup of 6 pull requests Successful merges: - #158026 (`RegionValues`: disable unnecessary range check) - #156795 (Handle generic reborrow in expression-use adjustment walking) - #157694 (Enhance documentation on wake call memory ordering) - #158034 (Fix reborrow source expression visits) - #158074 (Document transient connection errors from TcpListener::accept) - #158086 (renovate: Loosen dashboard approval and adopt recommended config)

…no-range-check, r=petrochenkov `RegionValues`: disable unnecessary range check Currently, when adding liveness points to region values in the `RegionValues` struct, the locations of the points are checked for ranges. This is unnecessarily cautious because they always are in range by construction. The docstring for the method used in the checks suggests that it was designed for underlying bit sets that currently aren't used for this. This adds documentation (including debug assertions) to make this clearer and removes the checks, which should have a strictly positive impact on performance.

…uwer Rollup of 10 pull requests Successful merges: - #158026 (`RegionValues`: disable unnecessary range check) - #156795 (Handle generic reborrow in expression-use adjustment walking) - #157694 (Enhance documentation on wake call memory ordering) - #157935 (Make `proc_macro::ConversionErrorKind` non exhaustive) - #158002 (Replace `unwrap` with `expect` in `get_module_children`) - #158034 (Fix reborrow source expression visits) - #158072 (Bump thin-vec to 0.2.18 to address RUSTSEC-2026-0103) - #158074 (Document transient connection errors from TcpListener::accept) - #158077 (rustdoc-json-types: Replace bincode dev-dependency with postcard) - #158086 (renovate: Loosen dashboard approval and adopt recommended config)

…eck, r=petrochenkov `RegionValues`: disable unnecessary range check Currently, when adding liveness points to region values in the `RegionValues` struct, the locations of the points are checked for ranges. This is unnecessarily cautious because they always are in range by construction. The docstring for the method used in the checks suggests that it was designed for underlying bit sets that currently aren't used for this. This adds documentation (including debug assertions) to make this clearer and removes the checks, which should have a strictly positive impact on performance.

JonathanBrouwer · 2026-06-18T17:25:58Z

@bors yield
Yielding to enclosing rollup

rust-bors · 2026-06-18T17:26:02Z

Auto build was cancelled. Cancelled workflows:

https://github.com/rust-lang/rust/actions/runs/27777245903

The next pull request likely to be tested is #158095.

…uwer Rollup of 10 pull requests Successful merges: - #158026 (`RegionValues`: disable unnecessary range check) - #156795 (Handle generic reborrow in expression-use adjustment walking) - #157694 (Enhance documentation on wake call memory ordering) - #157935 (Make `proc_macro::ConversionErrorKind` non exhaustive) - #158002 (Replace `unwrap` with `expect` in `get_module_children`) - #158034 (Fix reborrow source expression visits) - #158072 (Bump thin-vec to 0.2.18 to address RUSTSEC-2026-0103) - #158074 (Document transient connection errors from TcpListener::accept) - #158077 (rustdoc-json-types: Replace bincode dev-dependency with postcard) - #158086 (renovate: Loosen dashboard approval and adopt recommended config)

…eck, r=petrochenkov `RegionValues`: disable unnecessary range check Currently, when adding liveness points to region values in the `RegionValues` struct, the locations of the points are checked for ranges. This is unnecessarily cautious because they always are in range by construction. The docstring for the method used in the checks suggests that it was designed for underlying bit sets that currently aren't used for this. This adds documentation (including debug assertions) to make this clearer and removes the checks, which should have a strictly positive impact on performance.

rust-bors · 2026-06-18T18:26:56Z

💔 Test for 8509975 failed: CI. Failed job:

auto - x86_64-gnu-distcheck (web logs, enhanced plaintext logs)

JonathanBrouwer · 2026-06-18T19:45:52Z

@bors retry

Rollup of 2 pull requests Successful merges: - #158026 (`RegionValues`: disable unnecessary range check) - #158101 (Initialize directly in `From<T> for OnceLock<T>`)

Rollup merge of #158026 - amandasystems:region-values-point-no-range-check, r=petrochenkov `RegionValues`: disable unnecessary range check Currently, when adding liveness points to region values in the `RegionValues` struct, the locations of the points are checked for ranges. This is unnecessarily cautious because they always are in range by construction. The docstring for the method used in the checks suggests that it was designed for underlying bit sets that currently aren't used for this. This adds documentation (including debug assertions) to make this clearer and removes the checks, which should have a strictly positive impact on performance.

Rollup of 2 pull requests Successful merges: - rust-lang/rust#158026 (`RegionValues`: disable unnecessary range check) - rust-lang/rust#158101 (Initialize directly in `From<T> for OnceLock<T>`)

JonathanBrouwer · 2026-06-21T10:46:24Z

@rust-timer build eb4f67d

rust-timer · 2026-06-21T11:26:37Z

Finished benchmarking commit (eb4f67d): comparison URL.

Overall result: ✅ improvements - no action needed

Benchmarking means the PR may be perf-sensitive. Consider adding rollup=never if this change is not fit for rolling up.

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

Instruction count

Our most reliable metric. Used to determine the overall result above. However, even this metric can be noisy.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.2%	[-0.2%, -0.2%]	5
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary 4.6%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	4.6%	[3.9%, 5.3%]	2
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	4.6%	[3.9%, 5.3%]	2

Cycles

Results (secondary -3.5%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-3.5%	[-3.5%, -3.5%]	1
All ❌✅ (primary)	-	-	0

Binary size

This perf run didn't have relevant results for this metric.

Bootstrap: 482.188s -> 482.393s (0.04%)
Artifact size: 391.12 MiB -> 390.72 MiB (-0.10%)

rustbot assigned petrochenkov Jun 17, 2026

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. labels Jun 17, 2026

petrochenkov reviewed Jun 18, 2026

View reviewed changes

Comment thread compiler/rustc_borrowck/src/region_infer/values.rs Outdated

Comment thread compiler/rustc_borrowck/src/region_infer/values.rs Outdated

Comment thread compiler/rustc_borrowck/src/region_infer/values.rs

rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jun 18, 2026

amandasystems force-pushed the region-values-point-no-range-check branch from 8441082 to dbf6d75 Compare June 18, 2026 14:20

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jun 18, 2026

rust-bors Bot 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 Jun 18, 2026

JonathanBrouwer mentioned this pull request Jun 18, 2026

Rollup of 6 pull requests #158094

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JonathanBrouwer mentioned this pull request Jun 18, 2026

Rollup of 10 pull requests #158095

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rust-bors Bot 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 Jun 18, 2026

jhpratt mentioned this pull request Jun 18, 2026

Rollup of 2 pull requests #158104

Merged

rust-bors Bot merged commit 72979c1 into rust-lang:main Jun 19, 2026
2 of 14 checks passed

rustbot added this to the 1.98.0 milestone Jun 19, 2026

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rust-timer commented Jun 21, 2026

Overall result: ✅ improvements - no action needed

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