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@RalfJung RalfJung commented Dec 20, 2025

Now that this is directly available in the type, there's no reason to ever iterate in any other order.

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rustbot commented Dec 20, 2025

Some changes occurred to the CTFE machinery

cc @RalfJung, @oli-obk, @lcnr

Some changes occurred to the CTFE / Miri interpreter

cc @rust-lang/miri

The Miri subtree was changed

cc @rust-lang/miri

@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 Dec 20, 2025
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rustbot commented Dec 20, 2025

r? @nnethercote

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@bors try
@rust-timer queue

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rust-bors bot added a commit that referenced this pull request Dec 20, 2025
interpreter/visitor: always iterate in in-memory order
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@rustbot rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Dec 20, 2025
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rust-bors bot commented Dec 20, 2025

☀️ Try build successful (CI)
Build commit: 1ba2153 (1ba215368f7212da1a8a7476f2d2a4673b36b36d, parent: 838a912ced37a9f089e7c1a643d63ab5bc83f11b)

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Finished benchmarking commit (1ba2153): comparison URL.

Overall result: ✅ improvements - 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

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)
-1.1% [-1.1%, -1.1%] 2
All ❌✅ (primary) - - 0

Max RSS (memory usage)

Results (primary -1.1%)

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)
-1.1% [-1.1%, -1.1%] 1
Improvements ✅
(secondary)
- - 0
All ❌✅ (primary) -1.1% [-1.1%, -1.1%] 1

Cycles

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

Binary size

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

Bootstrap: 479.839s -> 478.221s (-0.34%)
Artifact size: 390.55 MiB -> 390.51 MiB (-0.01%)

@rustbot rustbot removed the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Dec 20, 2025
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And now with this fast-path.
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rust-bors bot added a commit that referenced this pull request Dec 20, 2025
interpreter/visitor: always iterate in in-memory order
@rustbot rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Dec 20, 2025
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rust-bors bot commented Dec 20, 2025

💥 Test timed out after 21600s

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RalfJung commented Dec 21, 2025 via email

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rust-bors bot added a commit that referenced this pull request Dec 21, 2025
interpreter/visitor: always iterate in in-memory order
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rust-bors bot commented Dec 21, 2025

☀️ Try build successful (CI)
Build commit: af4064f (af4064f905c860fd838b930297b638e290dc95b3, parent: cb79c42008b970269f6a06b257e5f04b93f24d03)

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Finished benchmarking commit (af4064f): 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)

Results (primary -1.7%)

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)
-1.7% [-1.7%, -1.7%] 1
Improvements ✅
(secondary)
- - 0
All ❌✅ (primary) -1.7% [-1.7%, -1.7%] 1

Cycles

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

Binary size

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

Bootstrap: 482.897s -> 480.88s (-0.42%)
Artifact size: 390.62 MiB -> 390.59 MiB (-0.01%)

@rustbot rustbot removed the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Dec 21, 2025
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oli-obk commented Dec 21, 2025

The fast path doesn't seem to be useful in our test suite

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RalfJung commented Dec 21, 2025 via email

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The first commit looks fine, it's a nice simplification.

As for the second commit, even if it doesn't help with the benchmarks, it would be nice to have at least one reported measurement that shows it speeds something up before adding the extra code.

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Is there a way to build a try toolchain that includes the "rustc-dev" component? That is required to build Miri against it...

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That might require infra work. So I'll take the 2nd commit out of this PR and make it a separate PR while we figure out the best way to benchmark the effect of rustc changes on Miri.

@RalfJung RalfJung force-pushed the visitor-in-mem-order branch from ca8a59a to 889ad15 Compare December 22, 2025 09:24
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@bors r=nnethercote

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bors commented Dec 22, 2025

📌 Commit 889ad15 has been approved by nnethercote

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 Dec 22, 2025
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