[TOY] Extend GVN to perform local value numbering. #143333

cjgillot · 2025-07-02T15:56:21Z

This PR is more a toy than anything else, but I still think the implementation is sound.

Current GVN MIR opt can be easily extended to track values that change inside a basic block. This PR attempts that.

r? @ghost for perf

cjgillot · 2025-07-05T14:13:23Z

[TOY] Extend GVN to perform local value numbering. This PR is more a toy than anything else, but I still think the implementation is sound. Current GVN MIR opt can be easily extended to track values that change inside a basic block. This PR attempts that. r? `@ghost` for perf

bors · 2025-07-05T14:14:39Z

⌛ Trying commit c3be10b with merge faceb52...

bors · 2025-07-05T17:10:23Z

☀️ Try build successful - checks-actions
Build commit: faceb52 (faceb52e72c06f94883ba351a73c83544ab4154b)

rust-timer · 2025-07-05T18:38:46Z

Finished benchmarking commit (faceb52): 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)	15.4%	[0.2%, 937.4%]	227
Regressions ❌ (secondary)	10.3%	[0.2%, 569.6%]	237
Improvements ✅ (primary)	-1.1%	[-1.8%, -0.4%]	2
Improvements ✅ (secondary)	-1.3%	[-4.1%, -0.3%]	16
All ❌✅ (primary)	15.3%	[-1.8%, 937.4%]	229

Max RSS (memory usage)

Results (primary 9.1%, secondary 2.4%)

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

	mean	range	count
Regressions ❌ (primary)	71.9%	[1.6%, 377.4%]	14
Regressions ❌ (secondary)	28.4%	[2.2%, 134.5%]	15
Improvements ✅ (primary)	-2.0%	[-7.5%, -0.7%]	79
Improvements ✅ (secondary)	-2.5%	[-3.5%, -0.8%]	80
All ❌✅ (primary)	9.1%	[-7.5%, 377.4%]	93

Cycles

Results (primary 44.8%, secondary 29.7%)

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

	mean	range	count
Regressions ❌ (primary)	46.5%	[2.3%, 299.4%]	27
Regressions ❌ (secondary)	40.6%	[2.4%, 263.2%]	28
Improvements ✅ (primary)	-2.1%	[-2.1%, -2.1%]	1
Improvements ✅ (secondary)	-4.2%	[-6.7%, -2.4%]	9
All ❌✅ (primary)	44.8%	[-2.1%, 299.4%]	28

Binary size

Results (primary -0.1%, 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)	0.2%	[0.0%, 0.6%]	37
Regressions ❌ (secondary)	0.5%	[0.0%, 1.7%]	70
Improvements ✅ (primary)	-0.3%	[-1.3%, -0.0%]	54
Improvements ✅ (secondary)	-1.0%	[-12.8%, -0.0%]	24
All ❌✅ (primary)	-0.1%	[-1.3%, 0.6%]	91

Bootstrap: 458.797s -> 582.037s (26.86%)
Artifact size: 372.11 MiB -> 361.76 MiB (-2.78%)

cjgillot · 2025-07-06T08:54:20Z

@bors try @rust-timer queue

[TOY] Extend GVN to perform local value numbering. This PR is more a toy than anything else, but I still think the implementation is sound. Current GVN MIR opt can be easily extended to track values that change inside a basic block. This PR attempts that. r? `@ghost` for perf

bors · 2025-07-06T08:55:31Z

⌛ Trying commit e521268 with merge dc4aa90...

cjgillot · 2025-07-06T08:56:01Z

@bors try @rust-timer queue

[TOY] Extend GVN to perform local value numbering. This PR is more a toy than anything else, but I still think the implementation is sound. Current GVN MIR opt can be easily extended to track values that change inside a basic block. This PR attempts that. r? `@ghost` for perf

bors · 2025-07-06T08:57:11Z

⌛ Trying commit 0293254 with merge 4d16c54...

bors · 2025-07-06T11:13:52Z

☀️ Try build successful - checks-actions
Build commit: 4d16c54 (4d16c544e50b0f84cc5347467c108e93106aa8f9)

rust-bors · 2025-08-24T01:23:48Z

☀️ Try build successful (CI)
Build commit: 1e45fee (1e45fee2f5452acaa981b7784932fd35cce6349e, parent: c5a6a7bdd89f099544fa0d3fad4d833d238377ad)

rust-timer · 2025-08-24T02:59:08Z

Finished benchmarking commit (1e45fee): 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)	3.2%	[0.5%, 12.8%]	17
Regressions ❌ (secondary)	3.4%	[0.3%, 11.6%]	15
Improvements ✅ (primary)	-0.5%	[-0.5%, -0.4%]	2
Improvements ✅ (secondary)	-0.5%	[-1.1%, -0.2%]	14
All ❌✅ (primary)	2.8%	[-0.5%, 12.8%]	19

Max RSS (memory usage)

Results (primary 58.2%, secondary 55.7%)

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

	mean	range	count
Regressions ❌ (primary)	69.5%	[1.8%, 288.2%]	11
Regressions ❌ (secondary)	55.7%	[2.2%, 150.0%]	7
Improvements ✅ (primary)	-4.1%	[-5.4%, -2.9%]	2
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	58.2%	[-5.4%, 288.2%]	13

Cycles

Results (primary 5.4%, secondary 11.6%)

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

	mean	range	count
Regressions ❌ (primary)	5.4%	[2.1%, 12.7%]	7
Regressions ❌ (secondary)	11.6%	[2.3%, 17.1%]	4
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	5.4%	[2.1%, 12.7%]	7

Binary size

Results (primary -0.1%, secondary -1.0%)

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

	mean	range	count
Regressions ❌ (primary)	0.3%	[0.1%, 0.4%]	6
Regressions ❌ (secondary)	0.4%	[0.1%, 1.0%]	4
Improvements ✅ (primary)	-0.1%	[-1.1%, -0.0%]	34
Improvements ✅ (secondary)	-1.6%	[-12.8%, -0.0%]	9
All ❌✅ (primary)	-0.1%	[-1.1%, 0.4%]	40

Bootstrap: 467.196s -> 479.382s (2.61%)
Artifact size: 378.17 MiB -> 378.25 MiB (0.02%)

bors · 2025-08-27T16:33:21Z

☔ The latest upstream changes (presumably #145923) made this pull request unmergeable. Please resolve the merge conflicts.

cjgillot · 2025-09-06T21:07:09Z

@bors try @rust-timer queue

[TOY] Extend GVN to perform local value numbering.

rust-bors · 2025-09-06T23:24:44Z

☀️ Try build successful (CI)
Build commit: e1059c0 (e1059c093c9366f7d49459a4527c600a458553d2, parent: bea625f3275e3c897dc965ed97a1d19ef7831f01)

rust-timer · 2025-09-07T01:14:03Z

Finished benchmarking commit (e1059c0): 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)	1.0%	[0.1%, 5.0%]	30
Regressions ❌ (secondary)	1.2%	[0.2%, 6.6%]	25
Improvements ✅ (primary)	-0.3%	[-0.6%, -0.2%]	8
Improvements ✅ (secondary)	-0.7%	[-2.9%, -0.1%]	38
All ❌✅ (primary)	0.7%	[-0.6%, 5.0%]	38

Max RSS (memory usage)

Results (primary 2.1%, secondary 4.0%)

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

	mean	range	count
Regressions ❌ (primary)	2.6%	[1.4%, 5.6%]	7
Regressions ❌ (secondary)	4.0%	[4.0%, 4.0%]	1
Improvements ✅ (primary)	-1.4%	[-1.4%, -1.4%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	2.1%	[-1.4%, 5.6%]	8

Cycles

Results (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)	-	-	0
Regressions ❌ (secondary)	2.7%	[2.7%, 2.7%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.1%	[-2.3%, -2.0%]	2
All ❌✅ (primary)	-	-	0

Binary size

Results (primary -0.1%, 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)	0.1%	[0.0%, 0.1%]	10
Regressions ❌ (secondary)	0.0%	[0.0%, 0.5%]	26
Improvements ✅ (primary)	-0.1%	[-2.0%, -0.0%]	57
Improvements ✅ (secondary)	-1.4%	[-12.8%, -0.0%]	11
All ❌✅ (primary)	-0.1%	[-2.0%, 0.1%]	67

Bootstrap: 468.001s -> 466.665s (-0.29%)
Artifact size: 387.44 MiB -> 387.54 MiB (0.03%)

bors · 2025-09-08T00:23:11Z

☔ The latest upstream changes (presumably #146304) made this pull request unmergeable. Please resolve the merge conflicts.

GVN: Ensure indirect is first projection in try_as_place. I haven't found any report for this bug on existing code, but managed to trigger it with rust-lang#143333

Rollup merge of #146298 - cjgillot:gvn-derefer, r=nnethercote GVN: Ensure indirect is first projection in try_as_place. I haven't found any report for this bug on existing code, but managed to trigger it with #143333

rustbot added the T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. label Jul 2, 2025