Reenable limited top-down MIR inlining

[JakobDegen]

Reverts most of #105119 and uses an alternative strategy to prevent exponential blowup. Specifically, we allow doing top-down inlining up to depth at most five, and for at most one call site per nested body.

r? @cjgillot

[rustbot]

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

[JakobDegen]

@bors try @rust-timer queue

[bors]

⌛ Trying commit ee6503a with merge a865f33a588ffb31c0260ef8947f00ab25dfa033...

[bors]

☀️ Try build successful - checks-actions
Build commit: a865f33a588ffb31c0260ef8947f00ab25dfa033 (a865f33a588ffb31c0260ef8947f00ab25dfa033)

[rust-timer]

Finished benchmarking commit (a865f33a588ffb31c0260ef8947f00ab25dfa033): 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)	0.4%	[0.2%, 1.1%]	20
Regressions ❌ (secondary)	0.6%	[0.3%, 1.7%]	11
Improvements ✅ (primary)	-0.4%	[-1.2%, -0.2%]	21
Improvements ✅ (secondary)	-0.7%	[-2.0%, -0.3%]	20
All ❌✅ (primary)	-0.0%	[-1.2%, 1.1%]	41

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)	2.3%	[0.8%, 4.1%]	5
Regressions ❌ (secondary)	3.2%	[3.2%, 3.2%]	1
Improvements ✅ (primary)	-2.1%	[-2.9%, -0.4%]	6
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-0.1%	[-2.9%, 4.1%]	11

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)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.0%	[-3.2%, -1.1%]	4
All ❌✅ (primary)	-	-	0

[cjgillot]

Thanks @JakobDegen.
Improvements pretty much balance regressions. Slightly more improvements than regressions in cycle average.
We are going back to the situation before the deactivation of MIR inlining.
@bors r+

[bors]

📌 Commit ee6503a has been approved by cjgillot

It is now in the queue for this repository.

[bors]

⌛ Testing commit ee6503a with merge 67d1617...

[bors]

☀️ Test successful - checks-actions
Approved by: cjgillot
Pushing 67d1617 to master...

[rust-timer]

Finished benchmarking commit (67d1617): 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)	0.5%	[0.3%, 1.1%]	4
Regressions ❌ (secondary)	0.6%	[0.5%, 0.6%]	4
Improvements ✅ (primary)	-0.6%	[-1.2%, -0.2%]	9
Improvements ✅ (secondary)	-0.9%	[-2.4%, -0.2%]	18
All ❌✅ (primary)	-0.2%	[-1.2%, 1.1%]	13

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)	2.0%	[1.0%, 4.3%]	9
Regressions ❌ (secondary)	2.1%	[1.6%, 2.7%]	5
Improvements ✅ (primary)	-2.5%	[-3.7%, -0.4%]	4
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.6%	[-3.7%, 4.3%]	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)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-3.5%	[-5.7%, -1.3%]	2
Improvements ✅ (secondary)	-1.9%	[-2.4%, -1.6%]	4
All ❌✅ (primary)	-3.5%	[-5.7%, -1.3%]	2

[rylev]

As pointed out here this was effectively a performance wash with regressions and improvements canceling themselves out.

@rustbot label +perf-regression-triaged