Perform simple scalar replacement of aggregates (SROA) MIR opt

[cjgillot]

This is a re-open of #85796

I copied the debuginfo implementation (first commit) from @eddyb's own SROA PR.

This pass replaces plain field accesses by simple locals when possible.
To be eligible, the replaced locals:

• must not be enums or unions;
• must not be used whole;
• must not have their address taken.

The storage and deinit statements are duplicated on each created local.

cc @tmiasko who reviewed the former version of this PR.

[rust-highfive]

r? @nagisa

(rust-highfive has picked a reviewer for you, use r? to override)

[rustbot]

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

Some changes occurred in compiler/rustc_codegen_gcc

cc @antoyo

[nagisa]

I don’t see myself finding the resources to get to reviewing this any time soon. I was kinda hoping to but all sorts of things keep coming up.

r? @rust-lang/wg-mir-opt

[nagisa]

r? mir-opt

[oli-obk]

Please turn on this optimization in release mode so we can do a perf test and a crater run

[oli-obk]

@bors try @rust-timer queue

[bors]

⌛ Trying commit 7b36296ae89744037f9e407a004b4f46199005d7 with merge 015dbcea68b7642e2acc268b5c8f3e9086fc02ff...

[bors]

☀️ Try build successful - checks-actions
Build commit: 015dbcea68b7642e2acc268b5c8f3e9086fc02ff (015dbcea68b7642e2acc268b5c8f3e9086fc02ff)

[rust-timer]

Finished benchmarking commit (015dbcea68b7642e2acc268b5c8f3e9086fc02ff): comparison URL.

Overall result: ✅ improvements - no 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.

@bors rollup=never
@rustbot label: +S-waiting-on-review -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
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.3%	[-0.4%, -0.2%]	21
Improvements ✅ (secondary)	-0.3%	[-0.6%, -0.2%]	16
All ❌✅ (primary)	-0.3%	[-0.4%, -0.2%]	21

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)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-4.4%	[-4.4%, -4.4%]	1
Improvements ✅ (secondary)	-3.6%	[-7.8%, -1.8%]	6
All ❌✅ (primary)	-4.4%	[-4.4%, -4.4%]	1

Cycles

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

[cjgillot]

@craterbot run mode=build-and-test

[craterbot]

👌 Experiment pr-102570 created and queued.
🤖 Automatically detected try build 015dbcea68b7642e2acc268b5c8f3e9086fc02ff
🔍 You can check out the queue and this experiment's details.

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

[craterbot]

🚧 Experiment pr-102570 is now running

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

[craterbot]

🎉 Experiment pr-102570 is completed!
📊 132 regressed and 96 fixed (247718 total)
📰 Open the full report.

⚠️ If you notice any spurious failure please add them to the blacklist!
ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

[cjgillot]

@craterbot run mode=build-and-test crates=https://crater-reports.s3.amazonaws.com/pr-102570/retry-regressed-list.txt

[craterbot]

👌 Experiment pr-102570-1 created and queued.
🤖 Automatically detected try build 015dbcea68b7642e2acc268b5c8f3e9086fc02ff
🔍 You can check out the queue and this experiment's details.

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

[bors]

⌛ Testing commit c0a6f49382ff3b9a25d7b27a2333ac7cf7164297 with merge fd098f068cff3f04ef6c067eee0beda9343ccedc...

[bors]

💔 Test failed - checks-actions

[cjgillot]

Tweaked the test to avoid depending on panic=unwind/abort.
@bors r=oli-obk

[bors]

📌 Commit a18de70 has been approved by oli-obk

It is now in the queue for this repository.

[bors]

⌛ Testing commit a18de70 with merge 79146ba...

[bors]

☀️ Test successful - checks-actions
Approved by: oli-obk
Pushing 79146ba to master...

[rust-timer]

Finished benchmarking commit (79146ba): comparison URL.

Overall result: ❌ regressions - 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)	0.2%	[0.2%, 0.2%]	2
Regressions ❌ (secondary)	0.4%	[0.2%, 0.8%]	6
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-1.4%	[-1.4%, -1.4%]	1
All ❌✅ (primary)	0.2%	[0.2%, 0.2%]	2

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)	-	-	0
Regressions ❌ (secondary)	1.7%	[1.7%, 1.7%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-4.6%	[-8.3%, -0.8%]	2
All ❌✅ (primary)	-	-	0

Cycles

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