Add #[inline] annotation to functions moved out of std::io

[bushrat011899]

Description

• Attempts to resolve compilation time regressions noted here.

Solution

Added #[inline] to public functions in alloc::io and core::io with total disregard to rhyme or reason. Might make things better, might make them worse, let's find out!

---

Notes

• No AI tooling of any kind was used during the creation of this bodge PR.

[rustbot]

r? @clarfonthey

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The reviewer was selected based on:

• Owners of files modified in this PR: libs
• libs expanded to 12 candidates
• Random selection from 6 candidates

[bushrat011899]

@JonathanBrouwer and/or @clarfonthey could we try a perf-run on this PR? I'm curious if this makes things better or worse for the core::io migration regressions.

[clarfonthey]

@bors try @rust-timer queue

Side note: very amused that this randomly chose me as the reviewer even though you didn't specify manually.

[rust-bors]

☀️ Try build successful (CI)
Build commit: 71248b2 (71248b2ef0eb27d87ea455b1bdc956e55f92e04c)
Base parent: 38a0576 (38a0576951fb5f7209c892b030f40ac166ae86b4)

[rust-timer]

Finished benchmarking commit (71248b2): comparison URL.

Overall result: ❌✅ regressions and improvements - please read:

Benchmarking means the PR may be perf-sensitive. It's automatically marked not fit for rolling up. Overriding is possible but disadvised: it risks changing compiler perf.

Next, please: If you can, justify the regressions found in this try perf run in writing along with @rustbot label: +perf-regression-triaged. If not, fix the regressions and do another perf run. Neutral or positive results will clear the label automatically.

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

Instruction count

Our most reliable metric. Used to determine the overall result above. However, even this metric can be noisy.

	mean	range	count
Regressions ❌ (primary)	1.2%	[1.0%, 1.4%]	2
Regressions ❌ (secondary)	0.2%	[0.2%, 0.3%]	2
Improvements ✅ (primary)	-1.0%	[-1.0%, -1.0%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.4%	[-1.0%, 1.4%]	3

Max RSS (memory usage)

Results (primary -2.2%, secondary 4.7%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	0.9%	[0.9%, 0.9%]	1
Regressions ❌ (secondary)	4.7%	[4.2%, 5.2%]	2
Improvements ✅ (primary)	-3.3%	[-3.9%, -2.2%]	3
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-2.2%	[-3.9%, 0.9%]	4

Cycles

Results (primary 2.8%, secondary -1.9%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	2.8%	[2.8%, 2.8%]	1
Regressions ❌ (secondary)	2.7%	[2.7%, 2.7%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-3.4%	[-3.5%, -3.2%]	3
All ❌✅ (primary)	2.8%	[2.8%, 2.8%]	1

Binary size

Results (primary 0.2%, secondary 0.2%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	0.3%	[0.0%, 1.6%]	6
Regressions ❌ (secondary)	0.2%	[0.0%, 0.3%]	2
Improvements ✅ (primary)	-0.5%	[-0.5%, -0.5%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.2%	[-0.5%, 1.6%]	7

Bootstrap: 489.951s -> 488.986s (-0.20%)
Artifact size: 389.41 MiB -> 390.00 MiB (0.15%)

[bushrat011899]

Ok so the most notable result I can see is the improvement to cargo, which I believe nullifies (most of) the negatives that came from moving Write. I'll need to double check, but I think ripgrep's regression here is actually the inverse of an improvement from the Error move.

Either way, I think it's clear that some of these functions probably shouldn't be inline. Now to work out which 🙃

EDIT:

Actually never mind ripgrep has just gotten worse with every migration. This PR reverts the worst regressions from Write, but adds doesn't help Error.