Fix non-deterministic encoding of syntax contexts by aerooneqq · Pull Request #161450 · rust-lang/rust

aerooneqq · 2026-08-21T10:20:19Z

Reiteration of #157409. Explanation can be found in comment for encoding_indices and in the issue.

No llms used.

petrochenkov · 2026-09-03T12:22:48Z

                    .collect()
            });
+
+            all_ctxt_data.sort_by_key(|&(ctxt, _)| self.get_encoding_index(ctxt));


Note: here and below get_encoding_index takes the encoding_indices in every iteration of the loop, it could be more efficient to take the lock once.

View changes since the review

I think we do not need locks at all, I replaced them with RefCells for now, can try to rewrite it without it.

petrochenkov · 2026-09-03T12:23:21Z

@bors try @rust-timer queue

…ing, r=<try> Fix non-deterministic encoding of syntax contexts

rust-bors · 2026-09-03T13:23:29Z

☀️ Try build successful (CI)
Build commit: 7e01adf (7e01adfdd3209974b2d32d2eb35d4173deaa540b)
Base parent: 4fcf397 (4fcf39725a9c99bd495d8c73af83628a256ff9a9)

rust-timer · 2026-09-03T14:14:37Z

Finished benchmarking commit (7e01adf): comparison URL.

Overall result: ❌ regressions - please read:

Benchmarking means the PR may be perf-sensitive. It's automatically marked not fit for rolling up. Overriding is possible but disadvised: it risks changing compiler perf.

Next, please: If you can, justify the regressions found in this try perf run in writing along with @rustbot label: +perf-regression-triaged. If not, fix the regressions and do another perf run. Neutral or positive results will clear the label automatically.

@bors rollup=never rustc-perf
@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)	0.6%	[0.1%, 1.9%]	72
Regressions ❌ (secondary)	0.6%	[0.1%, 1.7%]	50
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.6%	[0.1%, 1.9%]	72

Max RSS (memory usage)

Results (primary 1.0%, secondary -1.6%)

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

	mean	range	count
Regressions ❌ (primary)	1.0%	[1.0%, 1.0%]	1
Regressions ❌ (secondary)	3.7%	[2.6%, 4.9%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-3.7%	[-4.6%, -1.4%]	5
All ❌✅ (primary)	1.0%	[1.0%, 1.0%]	1

Cycles

Results (primary -0.2%, secondary 4.5%)

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

	mean	range	count
Regressions ❌ (primary)	2.3%	[2.3%, 2.3%]	1
Regressions ❌ (secondary)	4.5%	[4.5%, 4.5%]	1
Improvements ✅ (primary)	-2.7%	[-2.7%, -2.7%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-0.2%	[-2.7%, 2.3%]	2

Binary size

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

Bootstrap: 476.065s -> 474.462s (-0.34%)
Artifact size: 401.18 MiB -> 401.32 MiB (0.03%)

rust-bors · 2026-09-07T10:55:52Z

Unknown argument "rustc-timer". Did you mean to use @bors tryorreview``? Run @bors help or go to https://bors.rust-lang.org/help to see available commands.

rust-bors · 2026-09-07T11:52:02Z

☀️ Try build successful (CI)
Build commit: ea02f1d (ea02f1d3fee6db67e8e31ee4fedbf8d1990476ed)
Base parent: 32d94cc (32d94cc9be3f6e6c3fa1deaea9e0ab93c4980dba)

rust-timer · 2026-09-07T12:55:36Z

Finished benchmarking commit (ea02f1d): comparison URL.

Overall result: ❌✅ regressions and improvements - please read:

Benchmarking means the PR may be perf-sensitive. It's automatically marked not fit for rolling up. Overriding is possible but disadvised: it risks changing compiler perf.

Next, please: If you can, justify the regressions found in this try perf run in writing along with @rustbot label: +perf-regression-triaged. If not, fix the regressions and do another perf run. Neutral or positive results will clear the label automatically.

@bors rollup=never rustc-perf
@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)	0.2%	[0.2%, 0.3%]	7
Regressions ❌ (secondary)	0.2%	[0.2%, 0.3%]	4
Improvements ✅ (primary)	-0.3%	[-0.5%, -0.2%]	5
Improvements ✅ (secondary)	-0.5%	[-0.8%, -0.4%]	8
All ❌✅ (primary)	-0.0%	[-0.5%, 0.3%]	12

Max RSS (memory usage)

Results (primary -2.7%, secondary -2.3%)

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)	5.0%	[5.0%, 5.0%]	1
Improvements ✅ (primary)	-2.7%	[-2.7%, -2.7%]	1
Improvements ✅ (secondary)	-4.1%	[-4.5%, -3.2%]	4
All ❌✅ (primary)	-2.7%	[-2.7%, -2.7%]	1

Cycles

Results (secondary -2.6%)

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)	-2.6%	[-2.6%, -2.6%]	1
All ❌✅ (primary)	-	-	0

Binary size

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

Bootstrap: 477.995s -> 478.812s (0.17%)
Artifact size: 403.44 MiB -> 403.52 MiB (0.02%)

petrochenkov · 2026-09-08T09:27:23Z

@bors try @rust-timer queue

…ing, r=<try> Fix non-deterministic encoding of syntax contexts

rust-bors · 2026-09-08T10:34:43Z

☀️ Try build successful (CI)
Build commit: e742195 (e74219583a992b4baebf5794a9a39804c61b478a)
Base parent: a3e94c2 (a3e94c2ff51d6fa9929cf637fd85df3975119801)

rust-timer · 2026-09-08T12:39:58Z

Finished benchmarking commit (e742195): comparison URL.

Overall result: ❌✅ regressions and improvements - please read:

Benchmarking means the PR may be perf-sensitive. It's automatically marked not fit for rolling up. Overriding is possible but disadvised: it risks changing compiler perf.

Next, please: If you can, justify the regressions found in this try perf run in writing along with @rustbot label: +perf-regression-triaged. If not, fix the regressions and do another perf run. Neutral or positive results will clear the label automatically.

@bors rollup=never rustc-perf
@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)	0.2%	[0.2%, 0.2%]	2
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.3%	[-0.3%, -0.2%]	3
Improvements ✅ (secondary)	-0.5%	[-0.8%, -0.4%]	6
All ❌✅ (primary)	-0.1%	[-0.3%, 0.2%]	5

Max RSS (memory usage)

Results (primary 0.8%, secondary -1.5%)

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

	mean	range	count
Regressions ❌ (primary)	1.7%	[0.4%, 4.4%]	4
Regressions ❌ (secondary)	5.2%	[5.2%, 5.2%]	1
Improvements ✅ (primary)	-1.0%	[-1.5%, -0.5%]	2
Improvements ✅ (secondary)	-3.2%	[-3.9%, -2.0%]	4
All ❌✅ (primary)	0.8%	[-1.5%, 4.4%]	6

Cycles

Results (primary 0.4%, secondary 4.0%)

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

	mean	range	count
Regressions ❌ (primary)	1.2%	[0.4%, 2.5%]	3
Regressions ❌ (secondary)	4.0%	[4.0%, 4.0%]	1
Improvements ✅ (primary)	-0.7%	[-1.0%, -0.5%]	2
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.4%	[-1.0%, 2.5%]	5

Binary size

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

Bootstrap: 479.129s -> 477.217s (-0.40%)
Artifact size: 403.56 MiB -> 403.69 MiB (0.03%)

@petrochenkov

…nkov Refactor `HygieneEncodeContext` Some refactorings around `HygieneEncodeContext` with minor perf improvements, the most notable thing is that `Lock`s were removed. First part for rust-lang#161450. r? @petrochenkov

@petrochenkov

…nkov Refactor `HygieneEncodeContext` Some refactorings around `HygieneEncodeContext` with minor perf improvements, the most notable thing is that `Lock`s were removed. First part for rust-lang#161450. r? @petrochenkov

@petrochenkov

…nkov Refactor `HygieneEncodeContext` Some refactorings around `HygieneEncodeContext` with minor perf improvements, the most notable thing is that `Lock`s were removed. First part for rust-lang#161450. r? @petrochenkov

@petrochenkov

Refactor `HygieneEncodeContext` Some refactorings around `HygieneEncodeContext` with minor perf improvements, the most notable thing is that `Lock`s were removed. First part for #161450. r? @petrochenkov

@petrochenkov

…nkov Refactor `HygieneEncodeContext` Some refactorings around `HygieneEncodeContext` with minor perf improvements, the most notable thing is that `Lock`s were removed. First part for rust-lang#161450. r? @petrochenkov

@petrochenkov

Rollup merge of #162520 - aerooneqq:hygiene-perf, r=petrochenkov Refactor `HygieneEncodeContext` Some refactorings around `HygieneEncodeContext` with minor perf improvements, the most notable thing is that `Lock`s were removed. First part for #161450. r? @petrochenkov

rustbot · 2026-09-11T15:07:51Z

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

aerooneqq · 2026-09-11T15:21:45Z

@rustbot ready

rustbot added A-run-make Area: port run-make Makefiles to rmake.rs S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Aug 21, 2026

rustbot assigned petrochenkov Aug 21, 2026

rustbot added the T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. label Aug 21, 2026