Sandwich MIR optimizations between DSE.

[cjgillot]

This PR reorders MIR optimization passes in an attempt to increase their efficiency.

• Stop running CopyProp before GVN, it's useless as GVN will do the same thing anyway. Instead, we perform CopyProp at the end of the pipeline, to ensure we do not emit copy/move chains.
• Run DSE before GVN, as it increases the probability to have single-assignment locals.
• Run DSE after the final CopyProp to turn copies into moves.

r? @ghost

[cjgillot]

@bors try @rust-timer queue

[bors]

⌛ Trying commit bee69ed with merge da2b34d...

[bors]

☀️ Try build successful - checks-actions
Build commit: da2b34d (da2b34d645102a105976e2818671f2be9fc7cf06)

[rust-timer]

Finished benchmarking commit (da2b34d): 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)	0.8%	[0.2%, 4.7%]	19
Regressions ❌ (secondary)	0.4%	[0.2%, 0.8%]	12
Improvements ✅ (primary)	-1.0%	[-2.2%, -0.2%]	28
Improvements ✅ (secondary)	-0.8%	[-1.9%, -0.2%]	13
All ❌✅ (primary)	-0.2%	[-2.2%, 4.7%]	47

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)	4.8%	[1.9%, 14.4%]	5
Regressions ❌ (secondary)	3.8%	[1.7%, 9.5%]	4
Improvements ✅ (primary)	-1.6%	[-2.4%, -0.1%]	4
Improvements ✅ (secondary)	-5.1%	[-7.8%, -3.7%]	3
All ❌✅ (primary)	2.0%	[-2.4%, 14.4%]	9

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)	2.8%	[1.1%, 4.5%]	2
Regressions ❌ (secondary)	3.0%	[2.2%, 3.9%]	2
Improvements ✅ (primary)	-1.9%	[-2.4%, -1.4%]	8
Improvements ✅ (secondary)	-2.2%	[-2.3%, -2.0%]	3
All ❌✅ (primary)	-1.0%	[-2.4%, 4.5%]	10

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)	0.7%	[0.0%, 2.2%]	14
Regressions ❌ (secondary)	0.0%	[0.0%, 0.0%]	1
Improvements ✅ (primary)	-0.3%	[-1.0%, -0.0%]	69
Improvements ✅ (secondary)	-0.5%	[-1.1%, -0.2%]	21
All ❌✅ (primary)	-0.1%	[-1.0%, 2.2%]	83

Bootstrap: 668.367s -> 667.451s (-0.14%)
Artifact size: 308.49 MiB -> 308.66 MiB (0.05%)

[bors]

☔ The latest upstream changes (presumably #119767) made this pull request unmergeable. Please resolve the merge conflicts.

[bors]

☔ The latest upstream changes (presumably #119677) made this pull request unmergeable. Please resolve the merge conflicts.

[cjgillot]

Now that #119677 is merged.
@bors try @rust-timer queue

[bors]

⌛ Trying commit bc35ee4 with merge cc8825e...

[bors]

☀️ Try build successful - checks-actions
Build commit: cc8825e (cc8825e3c98ad94907c9ea8483edd15220baa7e3)

[rust-timer]

Finished benchmarking commit (cc8825e): 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)	0.7%	[0.1%, 1.2%]	12
Regressions ❌ (secondary)	0.5%	[0.2%, 1.8%]	10
Improvements ✅ (primary)	-1.1%	[-2.1%, -0.2%]	27
Improvements ✅ (secondary)	-1.0%	[-2.2%, -0.2%]	9
All ❌✅ (primary)	-0.5%	[-2.1%, 1.2%]	39

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)	2.4%	[0.9%, 3.6%]	6
Regressions ❌ (secondary)	2.6%	[2.1%, 3.1%]	2
Improvements ✅ (primary)	-4.0%	[-18.0%, -0.4%]	9
Improvements ✅ (secondary)	-8.4%	[-8.4%, -8.4%]	1
All ❌✅ (primary)	-1.4%	[-18.0%, 3.6%]	15

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%	[1.9%, 1.9%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-1.6%	[-2.6%, -0.5%]	9
Improvements ✅ (secondary)	-1.9%	[-3.3%, -0.9%]	5
All ❌✅ (primary)	-1.2%	[-2.6%, 1.9%]	10

Binary size

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

Bootstrap: 666.309s -> 663.818s (-0.37%)
Artifact size: 308.10 MiB -> 308.22 MiB (0.04%)

[rustbot]

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

[cjgillot]

Perf results: we get some nice speedups, near 2% for cargo, clap & ripgrep, which confirm the earlier perf run. On average, small improvements and small regressions balance out.
I propose to go ahead and merge this.
r? wg-mir-opt

[oli-obk]

@bors r+

[bors]

📌 Commit bc35ee4 has been approved by oli-obk

It is now in the queue for this repository.

[bors]

⌛ Testing commit bc35ee4 with merge 00b705e...

[bors]

💥 Test timed out

[rust-log-analyzer]

A job failed! Check out the build log: (web) (plain)

Click to see the possible cause of the failure (guessed by this bot)

[oli-obk]

@bors retry apple builder timeout

[bors]

⌛ Testing commit bc35ee4 with merge fa0dc20...

[bors]

☀️ Test successful - checks-actions
Approved by: oli-obk
Pushing fa0dc20 to master...

[rust-timer]

Finished benchmarking commit (fa0dc20): 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)	0.7%	[0.2%, 1.4%]	14
Regressions ❌ (secondary)	0.5%	[0.2%, 2.7%]	14
Improvements ✅ (primary)	-1.0%	[-2.2%, -0.2%]	31
Improvements ✅ (secondary)	-0.9%	[-2.2%, -0.2%]	10
All ❌✅ (primary)	-0.4%	[-2.2%, 1.4%]	45

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)	2.4%	[2.4%, 2.4%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-4.0%	[-7.9%, -0.7%]	6
Improvements ✅ (secondary)	-5.2%	[-8.2%, -3.1%]	3
All ❌✅ (primary)	-3.1%	[-7.9%, 2.4%]	7

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)	1.4%	[1.4%, 1.4%]	2
Regressions ❌ (secondary)	2.0%	[1.8%, 2.3%]	4
Improvements ✅ (primary)	-1.8%	[-2.7%, -1.1%]	11
Improvements ✅ (secondary)	-2.5%	[-3.1%, -2.0%]	3
All ❌✅ (primary)	-1.3%	[-2.7%, 1.4%]	13

Binary size

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

Bootstrap: 666.062s -> 664.881s (-0.18%)
Artifact size: 308.24 MiB -> 308.33 MiB (0.03%)

[lqd]

As seen in the previous runs: some nice wins on bigger benchmarks, and overall gains outweigh the few losses.

@rustbot label: +perf-regression-triaged