Always const-prop scalars and scalar pairs #113858

cjgillot · 2023-07-19T12:42:01Z

This removes some complexity from the pass.

The limitation to propagate ScalarPairs only for tuple comes from #67015, when ScalarPair constant were modeled using Rvalue::Aggregate. Nowadays, we use ConstValue::ByRef, which does not care about the underlying type.

The justification for not propagating in all cases was perf. This seems not to be a clear cut any more: #113858 (comment)

cjgillot · 2023-07-19T12:42:11Z

@bors try @rust-timer queue

bors · 2023-07-19T12:42:19Z

⌛ Trying commit fd83c9db1654bafcf104714ac4e8adf37896f907 with merge f0d8ed27c11d0230590142e813909c7b9b3530ca...

bors · 2023-07-19T13:58:42Z

☀️ Try build successful - checks-actions
Build commit: f0d8ed27c11d0230590142e813909c7b9b3530ca (f0d8ed27c11d0230590142e813909c7b9b3530ca)

bors · 2023-07-19T13:58:42Z

☀️ Try build successful - checks-actions
Build commit: f0d8ed27c11d0230590142e813909c7b9b3530ca (f0d8ed27c11d0230590142e813909c7b9b3530ca)

rust-timer · 2023-07-19T16:26:24Z

Finished benchmarking commit (f0d8ed27c11d0230590142e813909c7b9b3530ca): comparison URL.

Overall result: ❌✅ regressions and improvements - ACTION NEEDED

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. While you can manually mark this PR as fit for rollup, we strongly recommend not doing so since this PR may lead to changes in compiler perf.

Next Steps: If you can justify the regressions found in this try perf run, please indicate this with @rustbot label: +perf-regression-triaged along with sufficient written justification. If you cannot justify the regressions please fix the regressions and do another perf run. If the next run shows neutral or positive results, the label will be automatically removed.

@bors rollup=never
@rustbot label: -S-waiting-on-perf +perf-regression

Instruction count

This is a highly reliable metric that was used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	2.4%	[1.1%, 3.6%]	2
Regressions ❌ (secondary)	0.6%	[0.3%, 1.0%]	2
Improvements ✅ (primary)	-0.6%	[-1.3%, -0.3%]	8
Improvements ✅ (secondary)	-0.6%	[-0.9%, -0.3%]	5
All ❌✅ (primary)	0.0%	[-1.3%, 3.6%]	10

Max RSS (memory usage)

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	7.6%	[7.6%, 7.6%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-5.0%	[-12.3%, -2.0%]	4
Improvements ✅ (secondary)	-1.0%	[-1.0%, -1.0%]	1
All ❌✅ (primary)	-2.5%	[-12.3%, 7.6%]	5

Cycles

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	1.8%	[1.0%, 3.0%]	3
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-1.5%	[-1.9%, -1.2%]	2
Improvements ✅ (secondary)	-3.9%	[-3.9%, -3.9%]	1
All ❌✅ (primary)	0.5%	[-1.9%, 3.0%]	5

Binary size

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	0.2%	[0.0%, 0.6%]	18
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.4%	[-2.7%, -0.0%]	59
Improvements ✅ (secondary)	-1.9%	[-2.0%, -1.7%]	3
All ❌✅ (primary)	-0.3%	[-2.7%, 0.6%]	77

Bootstrap: 647.294s -> 648.53s (0.19%)

rustbot · 2023-07-19T20:57:19Z

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

cjgillot · 2023-07-19T20:57:23Z

r? compiler

oli-obk · 2023-07-20T07:43:32Z

r? @oli-obk

@bors r+

bors · 2023-07-20T07:43:34Z

📌 Commit fd83c9db1654bafcf104714ac4e8adf37896f907 has been approved by oli-obk

It is now in the queue for this repository.

bors · 2023-07-20T12:21:46Z

⌛ Testing commit fd83c9db1654bafcf104714ac4e8adf37896f907 with merge 412faf39e494910216abe24683848973b8f88593...

bors · 2023-07-20T12:24:37Z

💔 Test failed - checks-actions

oli-obk · 2023-07-20T12:52:25Z

@bors retry network

bors · 2023-07-20T18:10:04Z

☔ The latest upstream changes (presumably #113758) made this pull request unmergeable. Please resolve the merge conflicts.

cjgillot · 2023-07-20T21:39:31Z

Rebased.
@bors r=oli-obk

bors · 2023-07-20T21:39:33Z

📌 Commit 4a17740 has been approved by oli-obk

It is now in the queue for this repository.

bors · 2023-07-20T22:22:34Z

⌛ Testing commit 4a17740 with merge e2a7ba2...

scottmcm · 2023-07-20T23:19:29Z

tests/mir-opt/pre-codegen/checked_ops.checked_shl.PreCodegen.after.mir

        StorageLive(_3);
-        _3 = const 31_u32;
-        _4 = BitAnd(_2, move _3);
+        _3 = BitAnd(_2, const 31_u32);


Oh, thank you! I'd been confused why these kept sticking around.

(This'll help shrink slice::Iter::next, too, since today it still has _1 = 1; _3 = Offset(_2, _1); instead of Offset(_2, 1_usize).)

bors · 2023-07-21T00:11:35Z

☀️ Test successful - checks-actions
Approved by: oli-obk
Pushing e2a7ba2 to master...

rust-timer · 2023-07-21T02:01:32Z

Finished benchmarking commit (e2a7ba2): comparison URL.

Overall result: ❌✅ regressions and improvements - ACTION NEEDED

Next Steps: If you can justify the regressions found in this perf run, please indicate this with @rustbot label: +perf-regression-triaged along with sufficient written justification. If you cannot justify the regressions please open an issue or create a new PR that fixes the regressions, add a comment linking to the newly created issue or PR, and then add the perf-regression-triaged label to this PR.

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

Instruction count

This is a highly reliable metric that was used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	0.8%	[0.3%, 3.3%]	42
Regressions ❌ (secondary)	0.7%	[0.2%, 1.1%]	19
Improvements ✅ (primary)	-0.6%	[-1.3%, -0.2%]	6
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.6%	[-1.3%, 3.3%]	48

Max RSS (memory usage)

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	4.0%	[2.1%, 6.9%]	11
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-2.8%	[-3.7%, -1.9%]	2
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	2.9%	[-3.7%, 6.9%]	13

Cycles

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	1.9%	[1.0%, 2.9%]	2
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-1.1%	[-1.1%, -1.1%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.9%	[-1.1%, 2.9%]	3

Binary size

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	0.2%	[0.0%, 0.6%]	19
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.4%	[-2.3%, -0.0%]	54
Improvements ✅ (secondary)	-1.8%	[-1.9%, -1.7%]	3
All ❌✅ (primary)	-0.2%	[-2.3%, 0.6%]	73

Bootstrap: 650.713s -> 651.863s (0.18%)

pnkfelix · 2023-07-26T19:58:30Z

Visiting for weekly perf triage.

we didn't anticipate such a high impact to the instruction-counts; the trial run said there were two primary regressions here, not 42.
- exa-0.10.1 opt-full regressed by 3.34%
- five various bitmaps-3.1.0 profiles/scenarios regressed by 1.01% to 1.21%
- ripgrep-13.0.0 check-incr-unchanged regressed by 1.01%
- bunch of others that regressed by a little less than 1%... seems not great.
not marking as triaged.

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 19, 2023

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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 19, 2023

cjgillot marked this pull request as ready for review July 19, 2023 20:57

rustbot assigned petrochenkov Jul 19, 2023

rustbot assigned oli-obk Jul 20, 2023

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 20, 2023

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bors added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Jul 20, 2023

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bors added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Jul 20, 2023

cjgillot added 5 commits July 20, 2023 21:30

Always propagate into operands.

12a2edd

Also propagate ScalarPair operands.

895e215

Propagate ScalarPair for any type.

ccfa9af

Remove visit_terminator.

3f708ad

Inline should_const_prop.

4a17740

cjgillot force-pushed the const-prop-pairs branch from fd83c9d to 4a17740 Compare July 20, 2023 21:31

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-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jul 20, 2023

scottmcm reviewed Jul 20, 2023

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bors added the merged-by-bors This PR was explicitly merged by bors. label Jul 21, 2023

bors merged commit e2a7ba2 into rust-lang:master Jul 21, 2023

rustbot added this to the 1.73.0 milestone Jul 21, 2023

cjgillot deleted the const-prop-pairs branch July 21, 2023 07:39

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Always const-prop scalars and scalar pairs #113858

Always const-prop scalars and scalar pairs #113858

cjgillot commented Jul 19, 2023 •

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Always const-prop scalars and scalar pairs #113858

Always const-prop scalars and scalar pairs #113858

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Overall result: ❌✅ regressions and improvements - ACTION NEEDED

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Overall result: ❌✅ regressions and improvements - ACTION NEEDED

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