Allow more MIR SROA #144543

scottmcm · 2025-07-27T20:30:10Z

This removes some guards on SROA that are no longer needed:

With Ban projecting into repr(simd) types compiler-team#838 it no longer needs to check for SIMD
With Ban field-projecting into [rustc_layout_scalar_valid_range_*] types compiler-team#807 it no longer needs to check for niches
- This means that Wrapper(char) and Pin<&mut T> can get SRoA'd now, where previously they weren't because the check was banning SRaA for anything with a niche -- not just things with #[rustc_layout_scalar_valid_range_*].
- Technically Tracking issue for banning field projecting into [rustc_layout_scalar_valid_range_*] types (MCP807) #133652 isn't complete yet, but NonZero and NonNull have already moved over, so this is fine. At worst this will mean that LLVM gets less !range metadata on something that wasn't already fixed by Update NonZero and NonNull to not field-project (per MCP#807) #133651 or Update a bunch of library types for MCP807 #135236, but that's still sound, and unblocking general SRoA is worth that tradeoff.

rustbot · 2025-07-27T20:30:14Z

rustbot has assigned @lcnr.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

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rustbot · 2025-07-27T20:30:17Z

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

scottmcm · 2025-07-27T20:32:21Z

tests/mir-opt/inline_coroutine_body.run2-{closure#0}.Inline.panic-abort.diff

@@ -64,9 +64,8 @@
 +                             let mut _45: &mut std::future::Ready<()>;
 +                             let mut _46: &mut std::pin::Pin<&mut std::future::Ready<()>>;
 +                             scope 14 (inlined <Pin<&mut std::future::Ready<()>> as DerefMut>::deref_mut) {
-+                                 let mut _47: std::pin::Pin<&mut std::future::Ready<()>>;


annot: See how this Pin wrapper is now removed, when it previously couldn't be.

scottmcm · 2025-07-27T20:34:45Z

@bors try @rust-timer queue

Allow more MIR SROA

rust-bors · 2025-07-27T20:34:49Z

⌛ Trying commit 47bfa84 with merge d7a058b…

To cancel the try build, run the command @bors try cancel.

rust-bors · 2025-07-27T22:51:43Z

☀️ Try build successful (CI)
Build commit: d7a058b (d7a058b04fbf0f6a47f0680cd24eb12490080bd4, parent: 4b596bbd847672da87763b76171687d3544863c2)

rust-timer · 2025-07-28T00:22:29Z

Finished benchmarking commit (d7a058b): 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)	0.3%	[0.1%, 0.8%]	6
Regressions ❌ (secondary)	0.3%	[0.2%, 0.3%]	6
Improvements ✅ (primary)	-0.4%	[-0.6%, -0.2%]	4
Improvements ✅ (secondary)	-0.2%	[-0.2%, -0.2%]	2
All ❌✅ (primary)	0.0%	[-0.6%, 0.8%]	10

Max RSS (memory usage)

Results (primary 0.8%, secondary 2.9%)

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

	mean	range	count
Regressions ❌ (primary)	4.1%	[3.3%, 4.7%]	4
Regressions ❌ (secondary)	2.9%	[2.3%, 3.9%]	3
Improvements ✅ (primary)	-3.7%	[-5.5%, -2.1%]	3
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.8%	[-5.5%, 4.7%]	7

Cycles

Results (primary -2.6%, 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)	2.3%	[2.3%, 2.3%]	1
Improvements ✅ (primary)	-2.6%	[-2.6%, -2.6%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-2.6%	[-2.6%, -2.6%]	1

Binary size

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

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

	mean	range	count
Regressions ❌ (primary)	0.2%	[0.1%, 0.7%]	9
Regressions ❌ (secondary)	0.2%	[0.2%, 0.2%]	2
Improvements ✅ (primary)	-0.2%	[-0.6%, -0.0%]	19
Improvements ✅ (secondary)	-0.1%	[-0.1%, -0.0%]	7
All ❌✅ (primary)	-0.0%	[-0.6%, 0.7%]	28

Bootstrap: 466.325s -> 466.887s (0.12%)
Artifact size: 376.81 MiB -> 376.81 MiB (-0.00%)

scottmcm · 2025-07-28T01:48:39Z

Looks like this permuted codegen schedules (as is common for MIR changes that downstream affect inlining), so it's expected that there'd be ups and downs from it.

For example, the reason image-opt-full looks like

Is due to the different CGUs

cjgillot · 2025-07-28T01:48:44Z

Perf is neutral on average. I don't see many simplifications in the tests, but that may just be a lack of opportunities.

Still, I like having fewer special cases, so r=me if you want to go ahead as-is

scottmcm · 2025-07-28T01:52:53Z

Yeah, I think that avoiding using layout here is a good reason to take it. Maybe's not that common to wrap niched scalars into transparent newtypes, but we clearly should be SRoAing those cases when they happen.

@bors r=cjgillot

bors · 2025-07-28T01:52:56Z

📌 Commit 47bfa84 has been approved by cjgillot

It is now in the queue for this repository.

bors · 2025-07-28T11:53:19Z

⌛ Testing commit 47bfa84 with merge 9ba00e0...

bors · 2025-07-28T15:16:00Z

☀️ Test successful - checks-actions
Approved by: cjgillot
Pushing 9ba00e0 to master...

github-actions · 2025-07-28T15:19:28Z

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 65b6cdb (parent) -> 9ba00e0 (this PR)

Test differences

Show 3 test diffs

3 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 9ba00e0f9e00990fb88c1beac7172afe93b15609 --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

dist-x86_64-apple: 8190.2s -> 11486.0s (40.2%)
x86_64-apple-1: 7842.6s -> 6510.5s (-17.0%)
pr-check-2: 2686.6s -> 2267.7s (-15.6%)
x86_64-gnu-llvm-19: 2858.0s -> 2450.6s (-14.3%)
x86_64-apple-2: 4791.6s -> 4118.0s (-14.1%)
dist-aarch64-apple: 7587.6s -> 6553.4s (-13.6%)
aarch64-gnu-llvm-19-2: 2596.5s -> 2285.8s (-12.0%)
x86_64-rust-for-linux: 2974.3s -> 2624.6s (-11.8%)
tidy: 114.4s -> 102.6s (-10.3%)
i686-gnu-1: 8112.3s -> 7321.7s (-9.7%)

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.

rust-timer · 2025-07-28T16:34:56Z

Finished benchmarking commit (9ba00e0): 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)	0.5%	[0.2%, 0.8%]	3
Regressions ❌ (secondary)	0.3%	[0.2%, 0.3%]	6
Improvements ✅ (primary)	-0.4%	[-0.6%, -0.2%]	3
Improvements ✅ (secondary)	-0.9%	[-1.0%, -0.9%]	6
All ❌✅ (primary)	0.0%	[-0.6%, 0.8%]	6

Max RSS (memory usage)

Results (primary 1.9%, secondary 4.4%)

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

	mean	range	count
Regressions ❌ (primary)	4.0%	[1.2%, 5.3%]	5
Regressions ❌ (secondary)	4.4%	[4.4%, 4.4%]	1
Improvements ✅ (primary)	-3.3%	[-4.2%, -2.3%]	2
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	1.9%	[-4.2%, 5.3%]	7

Cycles

Results (primary 2.1%, 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)	2.1%	[2.0%, 2.1%]	2
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.3%	[-2.3%, -2.3%]	1
All ❌✅ (primary)	2.1%	[2.0%, 2.1%]	2

Binary size

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

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

	mean	range	count
Regressions ❌ (primary)	0.2%	[0.1%, 0.7%]	9
Regressions ❌ (secondary)	0.1%	[0.0%, 0.2%]	3
Improvements ✅ (primary)	-0.2%	[-0.6%, -0.0%]	19
Improvements ✅ (secondary)	-0.1%	[-0.1%, -0.0%]	7
All ❌✅ (primary)	-0.0%	[-0.6%, 0.7%]	28

Bootstrap: 468.035s -> 468.487s (0.10%)
Artifact size: 376.82 MiB -> 376.81 MiB (-0.00%)

lqd · 2025-07-28T16:52:34Z

Neutral results, worthwhile simplification, marking triaged as per #144543 (comment)

@rustbot label: +perf-regression-triaged

lqd · 2025-07-28T19:05:19Z

(for triagers) also: match-stress is currently noisy

Allow more MIR SROA

47bfa84

rustbot assigned lcnr Jul 27, 2025

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 Jul 27, 2025

scottmcm commented Jul 27, 2025

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rust-bors bot added a commit that referenced this pull request Jul 27, 2025

Auto merge of #144543 - scottmcm:more-sroa, r=<try>

d7a058b

Allow more MIR SROA

rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Jul 27, 2025

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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 Jul 28, 2025

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 Jul 28, 2025

lcnr assigned cjgillot and unassigned lcnr Jul 28, 2025

bors added the merged-by-bors This PR was explicitly merged by bors. label Jul 28, 2025

bors merged commit 9ba00e0 into rust-lang:master Jul 28, 2025
12 checks passed

rustbot added this to the 1.90.0 milestone Jul 28, 2025

bors mentioned this pull request Jul 28, 2025

Allow MIR-inlining Drop terminators too #144561

Draft

rustbot added the perf-regression-triaged The performance regression has been triaged. label Jul 28, 2025

scottmcm deleted the more-sroa branch July 29, 2025 06:00

This was referenced Jul 30, 2025

ICE building glam: Projecting into SIMD type std::arch::aarch64::float32x4_t is banned by MCP#838 #144621

Closed

Re-block SRoA on SIMD types #144665

Merged

This was referenced Aug 4, 2025

Rollup of 6 pull requests #144637

Merged

Rollup of 12 pull requests #144876

Merged

Allow more MIR SROA #144543

Allow more MIR SROA #144543

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

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Test differences

Job duration changes

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

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