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Merged
merged 1 commit into from
Nov 19, 2025
Merged

Avoid encoding non-constness or non-asyncness in metadata #149054

merged 1 commit into from
Nov 19, 2025
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@oli-obk
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@oli-obk oli-obk commented Nov 18, 2025

r? @fee1-dead

Let's see if we can get any benefit (even just metadata size) from not encoding the common case.

Inspired by #148434 (comment)

@rustbot 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 Nov 18, 2025
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oli-obk commented Nov 18, 2025

@bors try @rust-timer queue

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rust-bors bot added a commit that referenced this pull request Nov 18, 2025
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Auto merge of #149054 - oli-obk:min-encode, r=<try>
d435932 
Avoid encoding non-constness or non-asyncness in metadata
@rustbot rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Nov 18, 2025
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rust-bors bot commented Nov 18, 2025

☀️ Try build successful (CI)
Build commit: d435932 (d435932627c93b6e1003e0f9f63e2585c1258b55, parent: c1995621a44398ac33ab368adbfb69753218b49e)

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rust-timer commented Nov 18, 2025

Finished benchmarking commit (d435932): comparison URL.

Overall result: no relevant changes - no action needed

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

Instruction count

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

Max RSS (memory usage)

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

Cycles

Results (primary -2.2%, secondary -4.6%)

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)		 -2.2% [-2.2%, -2.2%] 1
Improvements ✅
(secondary)		 -4.6% [-6.7%, -2.5%] 2
All ❌✅ (primary) -2.2% [-2.2%, -2.2%] 1

Binary size

Results (primary -0.2%, secondary -0.4%)

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)		 -0.2% [-0.6%, -0.0%] 112
Improvements ✅
(secondary)		 -0.4% [-1.4%, -0.0%] 60
All ❌✅ (primary) -0.2% [-0.6%, -0.0%] 112

Bootstrap: 474.876s -> 472.742s (-0.45%)
Artifact size: 388.76 MiB -> 388.77 MiB (0.00%)

@rustbot rustbot removed the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Nov 18, 2025
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oli-obk commented Nov 18, 2025

Binary size reduction says this is def a thing, yay

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Kobzol commented Nov 18, 2025

Just to clarify, the binary size indeed comes from reduced crate metadata: https://perf.rust-lang.org/compare.html?start=c1995621a44398ac33ab368adbfb69753218b49e&end=d435932627c93b6e1003e0f9f63e2585c1258b55&stat=size%3Acrate_metadata.

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fee1-dead commented Nov 18, 2025

Yay!

@bors r+

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bors commented Nov 18, 2025

📌 Commit 357fd66 has been approved by fee1-dead

It is now in the queue for this repository.

@bors 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-review Status: Awaiting review from the assignee but also interested parties. labels Nov 18, 2025
cjgillot
cjgillot reviewed Nov 19, 2025
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compiler/rustc_metadata/src/rmeta/table.rs
}
}

impl FixedSizeEncoding for ty::Asyncness {
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Can we remove the other impl using fixed_size_enum!?

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@oli-obk oli-obk Nov 19, 2025

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on it, good catch

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bors commented Nov 19, 2025

⌛ Testing commit 357fd66 with merge 07bdbae...

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bors commented Nov 19, 2025

☀️ Test successful - checks-actions
Approved by: fee1-dead
Pushing 07bdbae to main...

@bors bors added the merged-by-bors This PR was explicitly merged by bors. label Nov 19, 2025
@bors bors merged commit 07bdbae into rust-lang:main Nov 19, 2025
13 checks passed
@rustbot rustbot added this to the 1.93.0 milestone Nov 19, 2025
@oli-obk oli-obk deleted the min-encode branch November 19, 2025 15:25
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github-actions bot commented Nov 19, 2025

What is this? This is an experimental post-merge analysis report that shows differences in test outcomes between the merged PR and its parent PR.

Comparing 140044c (parent) -> 07bdbae (this PR)

Test differences

Show 22 test diffs

22 doctest diffs were found. These are ignored, as they are noisy.

Test dashboard

Run

cargo run --manifest-path src/ci/citool/Cargo.toml -- \
    test-dashboard 07bdbaedc63094281483c40a88a1a8f2f8ffadc5 --output-dir test-dashboard

And then open test-dashboard/index.html in your browser to see an overview of all executed tests.

Job duration changes

  1. dist-apple-various: 3063.4s -> 4109.9s (+34.2%)
  2. x86_64-gnu-llvm-21-2: 5465.0s -> 6209.6s (+13.6%)
  3. aarch64-apple: 8794.4s -> 9872.8s (+12.3%)
  4. dist-i586-gnu-i586-i686-musl: 4785.7s -> 5356.1s (+11.9%)
  5. aarch64-gnu-debug: 4046.1s -> 4455.8s (+10.1%)
  6. x86_64-msvc-ext3: 6647.5s -> 6027.1s (-9.3%)
  7. x86_64-gnu-llvm-21-3: 5903.6s -> 6430.8s (+8.9%)
  8. x86_64-gnu-aux: 6377.1s -> 6924.4s (+8.6%)
  9. x86_64-gnu-llvm-20: 3170.9s -> 2904.8s (-8.4%)
  10. pr-check-2: 2619.6s -> 2419.1s (-7.7%)
How to interpret the job duration changes?

Job durations can vary a lot, based on the actual runner instance
that executed the job, system noise, invalidated caches, etc. The table above is provided
mostly for t-infra members, for simpler debugging of potential CI slow-downs.

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rust-timer commented Nov 19, 2025

Finished benchmarking commit (07bdbae): comparison URL.

Overall result: ❌✅ regressions and improvements - no action needed

@rustbot label: -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)		 0.1% [0.1%, 0.1%] 1
Improvements ✅
(primary)		 - - 0
Improvements ✅
(secondary)		 -0.8% [-0.8%, -0.8%] 2
All ❌✅ (primary) - - 0

Max RSS (memory usage)

Results (primary -2.0%)

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)		 -2.0% [-2.0%, -2.0%] 1
Improvements ✅
(secondary)		 - - 0
All ❌✅ (primary) -2.0% [-2.0%, -2.0%] 1

Cycles

Results (secondary 2.0%)

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)		 2.0% [1.4%, 2.6%] 2
Improvements ✅
(primary)		 - - 0
Improvements ✅
(secondary)		 - - 0
All ❌✅ (primary) - - 0

Binary size

Results (primary -0.2%, secondary -0.4%)

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)		 -0.2% [-0.6%, -0.0%] 112
Improvements ✅
(secondary)		 -0.4% [-1.4%, -0.0%] 60
All ❌✅ (primary) -0.2% [-0.6%, -0.0%] 112

Bootstrap: 474.2s -> 477.858s (0.77%)
Artifact size: 388.76 MiB -> 388.67 MiB (-0.02%)

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