Replace NullOp::SizeOf and NullOp::AlignOf by lang items. #147793

cjgillot · 2025-10-16T22:24:36Z

Fixes #119729
Keeps #136175 as it involves offset_of! which this PR does not touch.

cjgillot · 2025-10-16T22:33:04Z

Replace NullOp::SizeOf and NullOp::AlignOf by lang items.

rust-bors · 2025-10-17T00:45:10Z

☀️ Try build successful (CI)
Build commit: 2cefd8f (2cefd8ff4961f18771f6f840878942cbfbc03afe, parent: 53a741fc4b8cf2d8e7b1b2336ed8edf889db84f4)

rust-timer · 2025-10-17T01:54:54Z

Finished benchmarking commit (2cefd8f): comparison URL.

Overall result: ❌✅ regressions and improvements - please read the text below

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.

Next Steps: If you can justify the regressions found in this try perf run, please do so in sufficient writing along with @rustbot label: +perf-regression-triaged. If not, please fix the regressions and do another perf run. If its results are neutral or positive, the label will be automatically removed.

@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)	0.5%	[0.4%, 0.6%]	3
Regressions ❌ (secondary)	0.7%	[0.5%, 0.7%]	4
Improvements ✅ (primary)	-0.2%	[-0.2%, -0.1%]	2
Improvements ✅ (secondary)	-0.2%	[-0.7%, -0.1%]	14
All ❌✅ (primary)	0.2%	[-0.2%, 0.6%]	5

Max RSS (memory usage)

Results (primary -0.3%, secondary -1.4%)

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

	mean	range	count
Regressions ❌ (primary)	1.5%	[0.4%, 3.0%]	8
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-3.4%	[-7.6%, -1.1%]	5
Improvements ✅ (secondary)	-1.4%	[-2.2%, -0.8%]	3
All ❌✅ (primary)	-0.3%	[-7.6%, 3.0%]	13

Cycles

Results (primary -2.9%, secondary 6.8%)

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)	6.8%	[6.8%, 6.8%]	1
Improvements ✅ (primary)	-2.9%	[-2.9%, -2.9%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-2.9%	[-2.9%, -2.9%]	1

Binary size

Results (primary -0.0%, secondary -0.3%)

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

	mean	range	count
Regressions ❌ (primary)	0.1%	[0.0%, 0.5%]	22
Regressions ❌ (secondary)	0.0%	[0.0%, 0.1%]	11
Improvements ✅ (primary)	-0.2%	[-0.8%, -0.0%]	18
Improvements ✅ (secondary)	-1.2%	[-3.2%, -0.3%]	4
All ❌✅ (primary)	-0.0%	[-0.8%, 0.5%]	40

Bootstrap: 475.105s -> 474.369s (-0.15%)
Artifact size: 390.35 MiB -> 390.39 MiB (0.01%)

library/core/src/mem/mod.rs

compiler/rustc_const_eval/src/interpret/intrinsics.rs

library/core/src/mem/mod.rs

bors · 2025-10-23T05:09:28Z

⌛ Testing commit 5dfbf67 with merge 4b3ba58...

bors · 2025-10-23T08:15:56Z

☀️ Test successful - checks-actions
Approved by: scottmcm,oli-obk
Pushing 4b3ba58 to master...

github-actions · 2025-10-23T08:19:44Z

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 7838ce1 (parent) -> 4b3ba58 (this PR)

Test differences

Show 52 test diffs

Stage 1

[crashes] tests/crashes/114663.rs: pass -> [missing] (J1)
[crashes] tests/crashes/119729.rs: pass -> [missing] (J1)
[crashes] tests/crashes/136175.rs: pass -> [missing] (J1)
[ui] tests/ui/const-generics/generic_const_exprs/size_of-dyn-trait-2.rs: [missing] -> pass (J1)
[ui] tests/ui/const-generics/generic_const_exprs/size_of-dyn-trait-3.rs: [missing] -> pass (J1)
[ui] tests/ui/const-generics/generic_const_exprs/size_of-dyn-trait.rs: [missing] -> pass (J1)

Stage 2

[crashes] tests/crashes/114663.rs: pass -> [missing] (J0)
[crashes] tests/crashes/119729.rs: pass -> [missing] (J0)
[crashes] tests/crashes/136175.rs: pass -> [missing] (J0)
[ui] tests/ui/const-generics/generic_const_exprs/size_of-dyn-trait-2.rs: [missing] -> pass (J2)
[ui] tests/ui/const-generics/generic_const_exprs/size_of-dyn-trait-3.rs: [missing] -> pass (J2)
[ui] tests/ui/const-generics/generic_const_exprs/size_of-dyn-trait.rs: [missing] -> pass (J2)

Additionally, 40 doctest diffs were found. These are ignored, as they are noisy.

Job group index

Test dashboard

Run

cargo run --manifest-path src/ci/citool/Cargo.toml -- \
    test-dashboard 4b3ba5844e8831c9b3ee5a5643cdff5da0677426 --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

aarch64-apple: 8512.0s -> 6923.8s (-18.7%)
x86_64-gnu-llvm-20: 2404.1s -> 2842.5s (18.2%)
dist-x86_64-apple: 7185.0s -> 6096.5s (-15.2%)
dist-aarch64-apple: 6702.2s -> 5767.2s (-14.0%)
dist-various-2: 2223.4s -> 1967.1s (-11.5%)
armhf-gnu: 4926.0s -> 5489.8s (11.4%)
dist-armhf-linux: 4864.6s -> 5321.3s (9.4%)
x86_64-gnu-llvm-20-1: 3236.2s -> 3521.1s (8.8%)
x86_64-gnu-gcc: 3136.2s -> 3411.5s (8.8%)
arm-android: 5820.1s -> 6227.1s (7.0%)

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.

rust-timer · 2025-10-23T09:26:30Z

Finished benchmarking commit (4b3ba58): comparison URL.

Overall result: ❌✅ regressions and improvements - please read the text below

Our benchmarks found a performance regression caused by this PR.
This might be an actual regression, but it can also be just noise.

Next Steps:

If the regression was expected or you think it can be justified,
please write a comment with sufficient written justification, and add
@rustbot label: +perf-regression-triaged to it, to mark the regression as triaged.
If you think that you know of a way to resolve the regression, try to create
a new PR with a fix for the regression.
If you do not understand the regression or you think that it is just noise,
you can ask the @rust-lang/wg-compiler-performance working group for help (members of this group
were already notified of this PR).

@rustbot label: +perf-regression
cc @rust-lang/wg-compiler-performance

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%	[0.1%, 0.5%]	3
Regressions ❌ (secondary)	0.3%	[0.1%, 0.7%]	30
Improvements ✅ (primary)	-0.4%	[-0.7%, -0.1%]	4
Improvements ✅ (secondary)	-0.3%	[-0.7%, -0.1%]	5
All ❌✅ (primary)	-0.1%	[-0.7%, 0.5%]	7

Max RSS (memory usage)

Results (primary -0.1%, secondary 1.9%)

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

	mean	range	count
Regressions ❌ (primary)	2.2%	[0.5%, 4.8%]	5
Regressions ❌ (secondary)	3.5%	[0.6%, 6.3%]	18
Improvements ✅ (primary)	-2.3%	[-4.3%, -1.2%]	5
Improvements ✅ (secondary)	-1.8%	[-3.0%, -0.8%]	8
All ❌✅ (primary)	-0.1%	[-4.3%, 4.8%]	10

Cycles

Results (primary 1.3%, 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)	1.3%	[1.3%, 1.3%]	1
Regressions ❌ (secondary)	5.3%	[1.7%, 9.2%]	7
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-4.6%	[-13.1%, -2.0%]	15
All ❌✅ (primary)	1.3%	[1.3%, 1.3%]	1

Binary size

Results (primary -0.0%, secondary -0.1%)

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

	mean	range	count
Regressions ❌ (primary)	0.1%	[0.0%, 0.4%]	21
Regressions ❌ (secondary)	0.0%	[0.0%, 0.1%]	11
Improvements ✅ (primary)	-0.1%	[-0.8%, -0.0%]	19
Improvements ✅ (secondary)	-0.6%	[-0.8%, -0.3%]	3
All ❌✅ (primary)	-0.0%	[-0.8%, 0.4%]	40

Bootstrap: 473.667s -> 474.933s (0.27%)
Artifact size: 390.66 MiB -> 390.48 MiB (-0.05%)

Relevant upstream PR: - rust-lang/rust#147793 (Replace NullOp::SizeOf and NullOp::AlignOf by lang items.) Resolves: model-checking#4425

…ug-msg, r=Noratrieb,dianqk Improve the ICE message for invalid nullary intrinsic calls In rust-lang#148104, we found the panic message here rather confusing, and (if I'm reading the tea leaves right) that's because the intended audience for either side of the phrase is very different. I think this is more clear if/when this is encountered by users. I expect this ICE to be hit in practice by people calling the `size_of` and `align_of` intrinsics, so it's now _kind of_ helpful for those users too. The original effort to stop backends from needing to support nullary intrinsics added a note to all these const-only intrinsics, but when rust-lang#147793 ported two more the paragraph wasn't added. I've added it.

Rollup merge of #148118 - saethlin:nullary-intrinsic-check-bug-msg, r=Noratrieb,dianqk Improve the ICE message for invalid nullary intrinsic calls In #148104, we found the panic message here rather confusing, and (if I'm reading the tea leaves right) that's because the intended audience for either side of the phrase is very different. I think this is more clear if/when this is encountered by users. I expect this ICE to be hit in practice by people calling the `size_of` and `align_of` intrinsics, so it's now _kind of_ helpful for those users too. The original effort to stop backends from needing to support nullary intrinsics added a note to all these const-only intrinsics, but when #147793 ported two more the paragraph wasn't added. I've added it.

panstromek · 2025-10-27T15:34:27Z

perf triage:

Justified by #147793 (comment) and #147793 (comment). Post-merge results seem worse, mostly because there's some deep-vector spike that came back in #142712 (possibly noise?).

@rustbot label: +perf-regression-triaged

Relevant upstream PR: - rust-lang/rust#147793 (Replace NullOp::SizeOf and NullOp::AlignOf by lang items.) Resolves: #4425 By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 and MIT licenses. --------- Co-authored-by: thanhnguyen-aws <[email protected]>

Replace NullOp::SizeOf and NullOp::AlignOf by lang items. Part of rust-lang#146411 Fixes rust-lang#119729 Keeps rust-lang#136175 as it involves `offset_of!` which this PR does not touch. r? `@ghost`

oli-obk · 2025-11-19T08:40:29Z

compiler/rustc_const_eval/src/interpret/intrinsics.rs

            }
+            sym::size_of => {
+                let tp_ty = instance.args.type_at(0);
+                let layout = self.layout_of(tp_ty)?;


I think we need a monomorphic enough check here to avoid the cycle error from #149081

Can you say more oli? I could try to look at it, but I'm not sure what you mean here. Delay it until later? Skip evaluating it if there's a generic in here still? Use something like the transmute logic that can sometimes give sizes for generic things?

Oh, I should have expanded more -- I guess it's just another ensure_monomorphic_enough check.

Replace NullOp::SizeOf and NullOp::AlignOf by lang items. Part of rust-lang#146411 Fixes rust-lang#119729 Keeps rust-lang#136175 as it involves `offset_of!` which this PR does not touch. r? `@ghost`

…ug-msg, r=Noratrieb,dianqk Improve the ICE message for invalid nullary intrinsic calls In rust-lang#148104, we found the panic message here rather confusing, and (if I'm reading the tea leaves right) that's because the intended audience for either side of the phrase is very different. I think this is more clear if/when this is encountered by users. I expect this ICE to be hit in practice by people calling the `size_of` and `align_of` intrinsics, so it's now _kind of_ helpful for those users too. The original effort to stop backends from needing to support nullary intrinsics added a note to all these const-only intrinsics, but when rust-lang#147793 ported two more the paragraph wasn't added. I've added it.

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cjgillot force-pushed the no-null-op branch from 5ca7d48 to b335a91 Compare October 16, 2025 22:32

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rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Oct 16, 2025

rust-bors bot added a commit that referenced this pull request Oct 16, 2025

Auto merge of #147793 - cjgillot:no-null-op, r=<try>

2cefd8f

Replace NullOp::SizeOf and NullOp::AlignOf by lang items.

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rustbot added perf-regression Performance regression. and removed S-waiting-on-perf Status: Waiting on a perf run to be completed. labels Oct 17, 2025

cjgillot force-pushed the no-null-op branch from b335a91 to a785cc9 Compare October 17, 2025 01:57

rustbot added the T-clippy Relevant to the Clippy team. label Oct 17, 2025

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cjgillot force-pushed the no-null-op branch from a785cc9 to a70daae Compare October 17, 2025 02:36

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RalfJung reviewed Oct 17, 2025

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cjgillot force-pushed the no-null-op branch 2 times, most recently from fca4c69 to 27154a0 Compare October 17, 2025 17:59

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bors added the merged-by-bors This PR was explicitly merged by bors. label Oct 23, 2025

bors merged commit 4b3ba58 into rust-lang:master Oct 23, 2025
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rustbot added this to the 1.92.0 milestone Oct 23, 2025

bors mentioned this pull request Oct 23, 2025

[EXPERIMENT] Introduce TypingMode::Codegen to avoid layout cycles #145477

Draft

bors mentioned this pull request Oct 23, 2025

Remove box_new intrinsic #147862

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cjgillot deleted the no-null-op branch October 23, 2025 10:12

tautschnig added a commit to tautschnig/kani that referenced this pull request Oct 24, 2025

Upgrade Rust toolchain to 2025-10-24

d0592d0

Relevant upstream PR: - rust-lang/rust#147793 (Replace NullOp::SizeOf and NullOp::AlignOf by lang items.) Resolves: model-checking#4425

tautschnig mentioned this pull request Oct 24, 2025

Upgrade Rust toolchain to 2025-10-24 model-checking/kani#4426

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folkertdev mentioned this pull request Oct 25, 2025

ICE when using size_of in rust-lang/stdarch tests on i686-pc-windows-msvc #148104

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saethlin mentioned this pull request Oct 26, 2025

Improve the ICE message for invalid nullary intrinsic calls #148118

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rustbot added the perf-regression-triaged The performance regression has been triaged. label Oct 27, 2025

github-actions bot mentioned this pull request Oct 30, 2025

Toolchain upgrade to nightly-2025-11-25 flux-rs/flux#1345

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madsmtm mentioned this pull request Nov 19, 2025

1.92 regression in PyO3: unable to determine layout for ... because ... cannot be normalized #149081

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oli-obk reviewed Nov 19, 2025

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scottmcm mentioned this pull request Nov 20, 2025

See if this is the time we can remove layout::size_align #149109

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Replace NullOp::SizeOf and NullOp::AlignOf by lang items. #147793

Replace NullOp::SizeOf and NullOp::AlignOf by lang items. #147793

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rust-timer commented Oct 17, 2025

Overall result: ❌✅ regressions and improvements - please read the text below

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bors commented Oct 23, 2025

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github-actions bot commented Oct 23, 2025

Test differences

Stage 1

Stage 2

Job duration changes

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rust-timer commented Oct 23, 2025

Overall result: ❌✅ regressions and improvements - please read the text below

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panstromek commented Oct 27, 2025

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cjgillot commented Oct 16, 2025 •

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