Rewrite native thread-local storage

[joboet]

(part of #110897)

The current native thread-local storage implementation has become quite messy, uses indescriptive names and unnecessarily adds code to the macro expansion. This PR tries to fix that by using a new implementation that also allows more layout optimizations and potentially increases performance by eliminating unnecessary TLS accesses.

This does not change the recursive initialization behaviour I described in this comment, so it should be a library-only change. Changing that behaviour should be quite easy now, however.

r? @m-ou-se
@rustbot label +T-libs

[joboet]

@rustbot author
until I fix CI.

[ghost]

I have been impl'ing a lint in clippy to suggest const if possible, and it relies on this structure existing and returning exactly $init. As long as this doesn't change, the lint should keep working.

rust-lang/rust-clippy#12015

[bors]

☔ The latest upstream changes (presumably #117285) made this pull request unmergeable. Please resolve the merge conflicts.

[Dylan-DPC]

@joboet any updates on this? thanks

[joboet]

@rustbot label +S-blocked

I want to do some other cleanups before this can be merged.

[joboet]

@rustbot ready

The other improvements proposed by #110897 become much easier once this is merged, so I'm prioritising this one again.

[joboet]

I'm curious as to whether this affects performance. This should reduce the number of TLS accesses, after all.
@bors try @rust-timer queue

[bors]

☔ The latest upstream changes (presumably #124428) made this pull request unmergeable. Please resolve the merge conflicts.

[m-ou-se]

Thanks for working on this! This looks great.

Given that the average performance has improved, I'd say that the regressions are worth it. What do you think, @m-ou-se?

Agreed!

r=me after rebasing

[joboet]

@bors r-
@bors r=m-ou-se
Whoops!

[bors]

📌 Commit 60bf1ab has been approved by m-ou-se

It is now in the queue for this repository.

[ghost]

I haven't checked the code, but does the clippy lint work?

[joboet]

I haven't checked the code, but does the clippy lint work?

Yes, it should work.

[ghost]

Splendid, thank you very much!

[bors]

⌛ Testing commit 60bf1ab with merge 9c8a58f...

[bors]

☀️ Test successful - checks-actions
Approved by: m-ou-se
Pushing 9c8a58f to master...

[rust-timer]

Finished benchmarking commit (9c8a58f): 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)	0.4%	[0.2%, 1.2%]	10
Regressions ❌ (secondary)	1.0%	[0.7%, 1.6%]	9
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.4%	[0.2%, 1.2%]	10

Max RSS (memory usage)

Results (primary 6.9%, secondary 3.7%)

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)	10.4%	[4.8%, 16.5%]	3
Regressions ❌ (secondary)	3.7%	[3.5%, 3.9%]	2
Improvements ✅ (primary)	-3.4%	[-3.4%, -3.4%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	6.9%	[-3.4%, 16.5%]	4

Cycles

Results (primary 2.9%, secondary 3.2%)

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)	2.9%	[1.6%, 4.1%]	2
Regressions ❌ (secondary)	3.2%	[2.9%, 3.5%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	2.9%	[1.6%, 4.1%]	2

Binary size

Results (primary 0.1%, secondary 0.1%)

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)	0.3%	[0.0%, 0.7%]	34
Regressions ❌ (secondary)	0.1%	[0.0%, 0.1%]	38
Improvements ✅ (primary)	-0.2%	[-1.0%, -0.0%]	20
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.1%	[-1.0%, 0.7%]	54

Bootstrap: 673.262s -> 673.733s (0.07%)
Artifact size: 315.60 MiB -> 315.79 MiB (0.06%)