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@cjgillot cjgillot commented Jul 2, 2025

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

@rustbot rustbot added the T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. label Jul 2, 2025
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@cjgillot cjgillot force-pushed the local-value-numbering branch from c7dac45 to 62766e3 Compare July 2, 2025 22:11
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@cjgillot cjgillot added the A-mir-opt-GVN Area: MIR opt Global Value Numbering (GVN) label Jul 5, 2025
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cjgillot commented Jul 5, 2025

@bors try @rust-timer queue

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@rustbot rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Jul 5, 2025
bors added a commit that referenced this pull request Jul 5, 2025
[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
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bors commented Jul 5, 2025

⌛ Trying commit c3be10b with merge faceb52...

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bors commented Jul 5, 2025

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

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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%)

@rustbot rustbot added perf-regression Performance regression. and removed S-waiting-on-perf Status: Waiting on a perf run to be completed. labels Jul 5, 2025
@cjgillot cjgillot force-pushed the local-value-numbering branch from c3be10b to e521268 Compare July 6, 2025 08:54
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cjgillot commented Jul 6, 2025

@bors try @rust-timer queue

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@rustbot rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Jul 6, 2025
bors added a commit that referenced this pull request Jul 6, 2025
[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
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bors commented Jul 6, 2025

⌛ Trying commit e521268 with merge dc4aa90...

@cjgillot cjgillot force-pushed the local-value-numbering branch from e521268 to 0293254 Compare July 6, 2025 08:55
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cjgillot commented Jul 6, 2025

@bors try @rust-timer queue

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bors added a commit that referenced this pull request Jul 6, 2025
[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
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bors commented Jul 6, 2025

⌛ Trying commit 0293254 with merge 4d16c54...

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bors commented Jul 6, 2025

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

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bors commented Sep 17, 2025

☔ The latest upstream changes (presumably #146666) made this pull request unmergeable. Please resolve the merge conflicts.

@cjgillot cjgillot force-pushed the local-value-numbering branch from 48bb7ae to 477da90 Compare September 18, 2025 00:51
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bors commented Sep 19, 2025

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

@cjgillot cjgillot force-pushed the local-value-numbering branch from 477da90 to 2705998 Compare September 19, 2025 21:59
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Now that #145737 is merged.
@bors try @rust-timer queue

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rust-bors bot added a commit that referenced this pull request Sep 21, 2025
[TOY] Extend GVN to perform local value numbering.
@rustbot rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Sep 21, 2025
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rust-bors bot commented Sep 21, 2025

☀️ Try build successful (CI)
Build commit: 695bd40 (695bd40e2c808675c28012225875aeb7508ec032, parent: 1d23da6b7304d9e2a2c3dcb1b0aaa709cb9bc4ad)

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Finished benchmarking commit (695bd40): 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% [0.1%, 4.9%] 109
Regressions ❌
(secondary)
0.7% [0.1%, 6.5%] 55
Improvements ✅
(primary)
-0.6% [-0.9%, -0.4%] 4
Improvements ✅
(secondary)
-0.3% [-1.2%, -0.2%] 26
All ❌✅ (primary) 0.5% [-0.9%, 4.9%] 113

Max RSS (memory usage)

Results (primary 1.9%, secondary 4.6%)

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

mean range count
Regressions ❌
(primary)
1.9% [1.0%, 2.8%] 2
Regressions ❌
(secondary)
4.6% [3.1%, 5.0%] 8
Improvements ✅
(primary)
- - 0
Improvements ✅
(secondary)
- - 0
All ❌✅ (primary) 1.9% [1.0%, 2.8%] 2

Cycles

Results (primary 4.3%, secondary -0.7%)

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

mean range count
Regressions ❌
(primary)
4.3% [3.5%, 5.1%] 2
Regressions ❌
(secondary)
4.1% [3.2%, 5.7%] 3
Improvements ✅
(primary)
- - 0
Improvements ✅
(secondary)
-3.1% [-4.3%, -2.0%] 6
All ❌✅ (primary) 4.3% [3.5%, 5.1%] 2

Binary size

Results (primary -0.1%, 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%, 0.9%] 13
Regressions ❌
(secondary)
0.0% [0.0%, 0.3%] 39
Improvements ✅
(primary)
-0.1% [-2.1%, -0.0%] 46
Improvements ✅
(secondary)
-1.4% [-13.0%, -0.0%] 10
All ❌✅ (primary) -0.1% [-2.1%, 0.9%] 59

Bootstrap: 470.725s -> 472.748s (0.43%)
Artifact size: 387.92 MiB -> 390.07 MiB (0.55%)

@rustbot rustbot removed the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Sep 21, 2025
@cjgillot cjgillot force-pushed the local-value-numbering branch from 2705998 to aa12f6a Compare September 21, 2025 20:28
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@bors try @rust-timer queue

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rust-bors bot added a commit that referenced this pull request Sep 21, 2025
[TOY] Extend GVN to perform local value numbering.
@rustbot rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Sep 21, 2025
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rust-bors bot commented Sep 21, 2025

☀️ Try build successful (CI)
Build commit: ed91d44 (ed91d44e9b64826073d03e70308259977dc35b52, parent: 7e4b8d702fedccc9c7803773a22c2e053ac3b004)

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Finished benchmarking commit (ed91d44): 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%, 2.1%] 125
Regressions ❌
(secondary)
0.3% [0.1%, 0.7%] 62
Improvements ✅
(primary)
-0.6% [-0.9%, -0.3%] 5
Improvements ✅
(secondary)
-0.3% [-1.4%, -0.1%] 22
All ❌✅ (primary) 0.3% [-0.9%, 2.1%] 130

Max RSS (memory usage)

Results (primary -0.5%, secondary 3.4%)

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

mean range count
Regressions ❌
(primary)
0.8% [0.7%, 0.9%] 2
Regressions ❌
(secondary)
4.1% [1.0%, 5.0%] 9
Improvements ✅
(primary)
-1.7% [-2.7%, -0.6%] 2
Improvements ✅
(secondary)
-2.9% [-2.9%, -2.9%] 1
All ❌✅ (primary) -0.5% [-2.7%, 0.9%] 4

Cycles

Results (primary 2.0%, 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)
2.0% [1.7%, 2.3%] 2
Regressions ❌
(secondary)
- - 0
Improvements ✅
(primary)
- - 0
Improvements ✅
(secondary)
-2.9% [-5.3%, -2.0%] 8
All ❌✅ (primary) 2.0% [1.7%, 2.3%] 2

Binary size

Results (primary -0.1%, 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%, 0.8%] 13
Regressions ❌
(secondary)
0.0% [0.0%, 0.3%] 36
Improvements ✅
(primary)
-0.1% [-2.2%, -0.0%] 46
Improvements ✅
(secondary)
-1.4% [-13.0%, -0.0%] 10
All ❌✅ (primary) -0.1% [-2.2%, 0.8%] 59

Bootstrap: 471.863s -> 473.827s (0.42%)
Artifact size: 387.93 MiB -> 390.21 MiB (0.59%)

@rustbot rustbot removed the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Sep 21, 2025
github-actions bot pushed a commit to rust-lang/rustc-dev-guide that referenced this pull request Sep 22, 2025
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/rust#143333
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