GVN: Use a VnIndex in Address projection. #144477

cjgillot · 2025-07-26T00:57:00Z

The current implementation of address projections is inconsistent. Indexing semantically relies on the index' value, but the implementation uses the index' place. This PR fixes that by using ProjectionElem<VnIndex, Ty<'tcx>> instead of the raw PlaceElem<'tcx>.

This is a more principled fix than the workaround in #145030.

cjgillot · 2025-07-26T00:57:10Z

@bors try @rust-timer queue

rust-bors · 2025-07-26T00:57:14Z

⌛ Trying commit 783ac7a with merge 413faf3…

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

Gvn index

rust-bors · 2025-07-26T03:11:45Z

☀️ Try build successful (CI)
Build commit: 413faf3 (413faf3ee16ba890d3a82bfe8255e45c0aa5a4a5, parent: 430d6eddfc6a455ca4a0137c0822a982cccd3b2b)

rust-timer · 2025-07-26T09:32:25Z

Finished benchmarking commit (413faf3): comparison URL.

Overall result: ❌ regressions - 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)	1.0%	[0.4%, 1.6%]	2
Regressions ❌ (secondary)	0.8%	[0.0%, 1.6%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	1.0%	[0.4%, 1.6%]	2

Max RSS (memory usage)

Results (primary 0.1%, 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)	2.1%	[0.7%, 3.0%]	4
Regressions ❌ (secondary)	2.4%	[2.4%, 2.4%]	1
Improvements ✅ (primary)	-4.0%	[-4.0%, -4.0%]	2
Improvements ✅ (secondary)	-3.5%	[-4.6%, -2.2%]	3
All ❌✅ (primary)	0.1%	[-4.0%, 3.0%]	6

Cycles

Results (primary -3.7%)

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)	-3.7%	[-3.7%, -3.7%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-3.7%	[-3.7%, -3.7%]	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)	0.1%	[0.0%, 0.2%]	7
Regressions ❌ (secondary)	0.1%	[0.0%, 0.2%]	2
Improvements ✅ (primary)	-0.1%	[-0.2%, -0.0%]	2
Improvements ✅ (secondary)	-0.0%	[-0.0%, -0.0%]	3
All ❌✅ (primary)	0.0%	[-0.2%, 0.2%]	9

Bootstrap: 468.925s -> 469.927s (0.21%)
Artifact size: 374.68 MiB -> 374.75 MiB (0.02%)

cjgillot · 2025-08-08T00:39:30Z

@bors try @rust-timer queue

GVN: Use a VnIndex in Address projection.

rust-bors · 2025-08-08T00:39:34Z

⌛ Trying commit 5b541ef with merge 62808a4…

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

rust-bors · 2025-08-08T02:53:33Z

☀️ Try build successful (CI)
Build commit: 62808a4 (62808a420f38bf3827045bb6522bc69d15f26c7b, parent: 2fd855fbfc8239285aa2d596f76a8cc75e17ce02)

rust-timer · 2025-08-08T07:01:17Z

Finished benchmarking commit (62808a4): 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)	0.4%	[0.1%, 1.2%]	9
Regressions ❌ (secondary)	0.5%	[0.2%, 0.9%]	9
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.6%	[-0.6%, -0.5%]	3
All ❌✅ (primary)	0.4%	[0.1%, 1.2%]	9

Max RSS (memory usage)

Results (primary 1.2%, secondary 2.1%)

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

	mean	range	count
Regressions ❌ (primary)	1.7%	[0.5%, 3.4%]	5
Regressions ❌ (secondary)	2.1%	[0.8%, 3.0%]	3
Improvements ✅ (primary)	-1.1%	[-1.1%, -1.1%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	1.2%	[-1.1%, 3.4%]	6

Cycles

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

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)	0.0%	[0.0%, 0.0%]	5
Regressions ❌ (secondary)	0.0%	[0.0%, 0.0%]	3
Improvements ✅ (primary)	-0.2%	[-0.2%, -0.2%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-0.0%	[-0.2%, 0.0%]	6

Bootstrap: 465.394s -> 465.423s (0.01%)
Artifact size: 377.41 MiB -> 377.47 MiB (0.02%)

bors · 2025-08-23T09:14:49Z

☔ The latest upstream changes (presumably #145773) made this pull request unmergeable. Please resolve the merge conflicts.

bors · 2025-09-07T18:07:48Z

☔ The latest upstream changes (presumably #146289) made this pull request unmergeable. Please resolve the merge conflicts.

cjgillot · 2025-09-09T01:23:43Z

@bors try @rust-timer queue

rustbot · 2025-09-17T23:55:10Z

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

rustbot · 2025-09-17T23:55:12Z

r? @SparrowLii

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

Use r? to explicitly pick a reviewer

bors · 2025-09-19T16:19:00Z

☔ The latest upstream changes (presumably #145737) made this pull request unmergeable. Please resolve the merge conflicts.

SparrowLii · 2025-09-30T06:06:44Z

r? @dianqk Since they should be more familiar with gvn :)

rustbot · 2025-09-30T06:12:57Z

Requested reviewer is already assigned to this pull request.

Please choose another assignee.

rustbot · 2025-10-04T16:52:55Z

This PR was rebased onto a different master 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.

dianqk

LGTM.
r=me

View changes since this review

dianqk · 2025-10-06T04:45:11Z

tests/mir-opt/gvn_repeat.rs

    // CHECK-LABEL: fn repeat_local(
-    // CHECK: _0 = copy _3
+    // CHECK: let mut [[ELEM:.*]]: &i32;
+    // CHECK: _0 = copy (*[[ELEM]]);


Should we leave a FIXME here?

The new result is more correct, so I'd rather not. The current annotation was more of a bug: idx1 is not SSA, so we should never have been able to refer to &array[idx1].

cjgillot · 2025-10-06T11:49:32Z

@bors r=dianqk

bors · 2025-10-06T11:49:35Z

📌 Commit 3d96e54 has been approved by dianqk

It is now in the queue for this repository.

bors · 2025-10-06T15:33:20Z

⌛ Testing commit 3d96e54 with merge 3d8c1c1...

bors · 2025-10-06T18:41:42Z

☀️ Test successful - checks-actions
Approved by: dianqk
Pushing 3d8c1c1 to master...

github-actions · 2025-10-06T18:45:06Z

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 8111a2d (parent) -> 3d8c1c1 (this PR)

Test differences

Show 2 test diffs

2 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 3d8c1c1fc077d04658de63261d8ce2903546db13 --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-aarch64-linux: 6400.6s -> 8556.9s (33.7%)
x86_64-rust-for-linux: 3076.5s -> 2546.6s (-17.2%)
aarch64-msvc-1: 7742.6s -> 6702.6s (-13.4%)
x86_64-gnu-tools: 3802.2s -> 3314.7s (-12.8%)
aarch64-gnu: 7037.5s -> 6247.8s (-11.2%)
i686-gnu-1: 8218.4s -> 7297.5s (-11.2%)
aarch64-apple: 9229.1s -> 10229.8s (10.8%)
dist-x86_64-msvc: 7576.5s -> 6795.6s (-10.3%)
i686-gnu-2: 6031.5s -> 5432.5s (-9.9%)
x86_64-gnu-llvm-20-1: 3530.3s -> 3189.4s (-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 · 2025-10-06T20:10:13Z

Finished benchmarking commit (3d8c1c1): 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)	0.6%	[0.5%, 0.6%]	3
Improvements ✅ (primary)	-0.4%	[-0.4%, -0.4%]	1
Improvements ✅ (secondary)	-0.0%	[-0.0%, -0.0%]	1
All ❌✅ (primary)	-0.4%	[-0.4%, -0.4%]	1

Max RSS (memory usage)

Results (primary 5.1%, secondary 0.5%)

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

	mean	range	count
Regressions ❌ (primary)	5.1%	[2.4%, 7.8%]	2
Regressions ❌ (secondary)	4.2%	[4.2%, 4.2%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-1.3%	[-1.6%, -1.0%]	2
All ❌✅ (primary)	5.1%	[2.4%, 7.8%]	2

Cycles

Results (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%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

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)	0.1%	[0.0%, 0.1%]	8
Regressions ❌ (secondary)	0.1%	[0.1%, 0.1%]	2
Improvements ✅ (primary)	-0.1%	[-0.2%, -0.0%]	4
Improvements ✅ (secondary)	-0.1%	[-0.1%, -0.0%]	2
All ❌✅ (primary)	0.0%	[-0.2%, 0.1%]	12

Bootstrap: 471.909s -> 472.01s (0.02%)
Artifact size: 388.29 MiB -> 388.39 MiB (0.03%)

rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Jul 26, 2025

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rust-bors bot added a commit that referenced this pull request Jul 26, 2025

Auto merge of #144477 - cjgillot:gvn-index, r=<try>

413faf3

Gvn index

rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Jul 26, 2025

cjgillot changed the title ~~Gvn index~~ GVN: Use a VnIndex in Address projection. Jul 26, 2025

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rustbot removed the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Jul 26, 2025

cjgillot force-pushed the gvn-index branch from 783ac7a to c169ed7 Compare July 29, 2025 01:32

cjgillot force-pushed the gvn-index branch from c169ed7 to 5b541ef Compare August 8, 2025 00:39

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rust-bors bot added a commit that referenced this pull request Aug 8, 2025

Auto merge of #144477 - cjgillot:gvn-index, r=<try>

62808a4

GVN: Use a VnIndex in Address projection.

rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Aug 8, 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 Aug 8, 2025

cjgillot force-pushed the gvn-index branch from 5b541ef to bcf7fbc Compare August 16, 2025 16:43

cjgillot force-pushed the gvn-index branch from bcf7fbc to 525d69c Compare August 23, 2025 18:31

cjgillot force-pushed the gvn-index branch from 525d69c to cd5386c Compare September 9, 2025 01:18

rustbot removed the S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. label Sep 17, 2025

rustbot assigned SparrowLii Sep 17, 2025

cjgillot force-pushed the gvn-index branch from c5e2829 to f092b9b Compare September 19, 2025 21:59

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rustbot assigned dianqk and unassigned SparrowLii Sep 30, 2025

cjgillot added 2 commits October 4, 2025 16:36

Make Value Copy by arena-allocating vectors.

1180278

Use a VnIndex in Address projection.

3d96e54

cjgillot force-pushed the gvn-index branch from f092b9b to 3d96e54 Compare October 4, 2025 16:52

dianqk approved these changes Oct 6, 2025

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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 Oct 6, 2025

bors added the merged-by-bors This PR was explicitly merged by bors. label Oct 6, 2025

bors merged commit 3d8c1c1 into rust-lang:master Oct 6, 2025
11 checks passed

rustbot added this to the 1.92.0 milestone Oct 6, 2025

cjgillot deleted the gvn-index branch October 6, 2025 19:12

cjgillot mentioned this pull request Oct 6, 2025

GVN: Support unions. #146355

Merged

bors mentioned this pull request Oct 6, 2025

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

Draft

GVN: Use a VnIndex in Address projection. #144477

GVN: Use a VnIndex in Address projection. #144477

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Overall result: ❌ regressions - no action needed

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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 - no action needed

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