Use Arc as Lrc for parallel compiler

[SparrowLii]

part of #101566

Test perf of Lrc and make optimization

[rustbot]

r? @jackh726

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[SparrowLii]

@bors try @rust-timer queue

[bors]

⌛ Trying commit 8c40102 with merge b1dc84ef05b47984bedf7ee679a75b84d7854b59...

[bors]

☀️ Try build successful - checks-actions
Build commit: b1dc84ef05b47984bedf7ee679a75b84d7854b59 (b1dc84ef05b47984bedf7ee679a75b84d7854b59)

[rust-timer]

Finished benchmarking commit (b1dc84ef05b47984bedf7ee679a75b84d7854b59): 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-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)	0.5%	[0.5%, 0.5%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-1.4%	[-4.7%, -0.4%]	19
All ❌✅ (primary)	-	-	0

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)	0.7%	[0.7%, 0.7%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.8%	[-0.9%, -0.8%]	3
All ❌✅ (primary)	-	-	0

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)	0.6%	[0.5%, 0.7%]	4
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.5%	[-0.6%, -0.4%]	2
All ❌✅ (primary)	-	-	0

[jackh726]

@SparrowLii what do you want to do with this PR?

@rustbot author

[SparrowLii]

@jackh726 This is a step to land parallel compiler. Since use Arc as Lrc doesn't impact the perf, I think we can just replace it

[SparrowLii]

I think we can just leave it here and merge it when the other work of parallel compilation is done.

[jackh726]

I'm not sure it's worth leaving this open for some undefined period of time. Perf seems good enough to merge if you'd like to do that. Otherwise, I think we should just close it.

[SparrowLii]

That makes sense. We'd better close it now