Ignore the always part of #[inline(always)] in MIR inlining

[saethlin]

#[inline(always)] is used in two cases: for functions that are so trivial it is always profitable to inline them, but also for functions which LLVM thinks are a bad inlining candidate, but which actually turn out to be profitable to inline. That second justification doesn't apply to the MIR inliner, so ignoring our cost estimation for these functions is not necessarily the right right thing to do.

This is basically a wash on non-check runs and a perf benefit in check runs. There are some notable regressions, and I think we might be able to claw those back by turning #[inline(always)] into a stronger hint. But I think this PR stands decently on its own as a tidy simplification.

[saethlin]

@bors try @rust-timer queue

[bors]

⌛ Trying commit 5d45d72cd8a4201dfe98ec28d676e2e569d47197 with merge 988256e3d645e9cda49a57c23c799a49d7513fc3...

[bors]

☀️ Try build successful - checks-actions
Build commit: 988256e3d645e9cda49a57c23c799a49d7513fc3 (988256e3d645e9cda49a57c23c799a49d7513fc3)

[rust-timer]

Finished benchmarking commit (988256e3d645e9cda49a57c23c799a49d7513fc3): 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)	1.1%	[0.2%, 2.3%]	9
Regressions ❌ (secondary)	1.0%	[0.3%, 1.8%]	4
Improvements ✅ (primary)	-0.4%	[-2.1%, -0.2%]	112
Improvements ✅ (secondary)	-0.4%	[-0.8%, -0.2%]	46
All ❌✅ (primary)	-0.3%	[-2.1%, 2.3%]	121

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)	4.6%	[1.0%, 6.8%]	4
Regressions ❌ (secondary)	2.1%	[2.1%, 2.1%]	1
Improvements ✅ (primary)	-5.0%	[-9.6%, -2.1%]	3
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.5%	[-9.6%, 6.8%]	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)	1.2%	[0.7%, 2.0%]	3
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-2.7%	[-2.7%, -2.7%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.2%	[-2.7%, 2.0%]	4

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%, 0.5%]	9
Regressions ❌ (secondary)	0.0%	[0.0%, 0.0%]	4
Improvements ✅ (primary)	-0.5%	[-11.1%, -0.0%]	55
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-0.4%	[-11.1%, 0.5%]	64

Bootstrap: 646.397s -> 653.496s (1.10%)

[saethlin]

r? mir-opt

[rustbot]

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

The Miri subtree was changed

cc @rust-lang/miri

[RalfJung]

The justification for this change should be recorded in the code itself via a comment. Otherwise someone is bound to accidentally revert this eventually.

[bors]

☔ The latest upstream changes (presumably #112418) made this pull request unmergeable. Please resolve the merge conflicts.

[oli-obk]

@bors r+

[bors]

📌 Commit b604e358063f8d392f05b87e506933597f662a59 has been approved by oli-obk

It is now in the queue for this repository.

[bors]

☔ The latest upstream changes (presumably #112346) made this pull request unmergeable. Please resolve the merge conflicts.

[saethlin]

@oli-obk I think in the rebase I tweaked some of the way I patched up some of the mir-opt tests. Wouldn't hurt for you to take a look and make sure you still agree with what I've done.

[oli-obk]

@bors r+

[bors]

📌 Commit c153f3a has been approved by oli-obk

It is now in the queue for this repository.

[bors]

⌛ Testing commit c153f3a with merge 6bba061...

[bors]

☀️ Test successful - checks-actions
Approved by: oli-obk
Pushing 6bba061 to master...

[rust-timer]

Finished benchmarking commit (6bba061): 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)	1.7%	[1.2%, 2.5%]	8
Regressions ❌ (secondary)	0.6%	[0.2%, 1.4%]	7
Improvements ✅ (primary)	-0.4%	[-3.0%, -0.2%]	61
Improvements ✅ (secondary)	-0.4%	[-1.0%, -0.2%]	18
All ❌✅ (primary)	-0.1%	[-3.0%, 2.5%]	69

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)	4.5%	[2.7%, 6.2%]	3
Regressions ❌ (secondary)	2.8%	[2.8%, 2.8%]	1
Improvements ✅ (primary)	-6.0%	[-15.3%, -1.5%]	7
Improvements ✅ (secondary)	-2.5%	[-3.1%, -2.1%]	3
All ❌✅ (primary)	-2.9%	[-15.3%, 6.2%]	10

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)	1.6%	[1.3%, 2.2%]	4
Regressions ❌ (secondary)	2.7%	[2.7%, 2.7%]	1
Improvements ✅ (primary)	-2.7%	[-3.1%, -2.3%]	2
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.1%	[-3.1%, 2.2%]	6

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%, 0.4%]	8
Regressions ❌ (secondary)	0.0%	[0.0%, 0.0%]	4
Improvements ✅ (primary)	-0.6%	[-13.3%, -0.0%]	59
Improvements ✅ (secondary)	-1.4%	[-1.4%, -1.4%]	1
All ❌✅ (primary)	-0.5%	[-13.3%, 0.4%]	67

Bootstrap: 646.921s -> 655.492s (1.32%)

[rylev]

Since the perf regressions are justified in the PR description, I'll mark this as triaged.

@rustbot label: +perf-regression-triaged