use triomphe::Arc for InternedObligationCauseCode instead of Arc

[klensy]

This nicely cuts memory reads (reported by dhat), while marginally reducing maxrss for some stresstest (#125267 (comment)).

Lets see perf?

[rustbot]

r? @Nadrieril

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[rustbot]

The list of allowed third-party dependencies may have been modified! You must ensure that any new dependencies have compatible licenses before merging.

cc @davidtwco, @wesleywiser

These commits modify the Cargo.lock file. Unintentional changes to Cargo.lock can be introduced when switching branches and rebasing PRs.

If this was unintentional then you should revert the changes before this PR is merged.
Otherwise, you can ignore this comment.

[Nadrieril]

@bors try @rust-timer queue

[bors]

⌛ Trying commit b470b56 with merge ee89a51...

[bors]

☀️ Try build successful - checks-actions
Build commit: ee89a51 (ee89a51b4014bff6890f761267fc68bfaf28ec48)

[rust-timer]

Finished benchmarking commit (ee89a51): comparison URL.

Overall result: no relevant changes - 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 benchmark run did not return any relevant results for this metric.

Max RSS (memory usage)

Results (primary 1.5%)

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)	1.5%	[1.5%, 1.5%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	1.5%	[1.5%, 1.5%]	1

Cycles

This benchmark run did not return any relevant results for this metric.

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 790.759s -> 790.962s (0.03%)
Artifact size: 350.03 MiB -> 350.05 MiB (0.01%)

[compiler-errors]

I personally don't think this justifies changing the impl

[klensy]

Very small instructions and maxrss improvement, but can be spurious (with non-relevant checked.), i'll see what can be done.

I personally don't think this justifies changing the impl

Actual change is only one line:

-    code: Option<Arc<ObligationCauseCode<'tcx>>>,
+    code: Option<triomphe::Arc<ObligationCauseCode<'tcx>>>,

all other changes is copy&paste of Arc impls.

[compiler-errors]

What I mean is relying on an alternative, out-of-tree implementation of Arc for literally minimal perf changes.

[alex-semenyuk]

Triage: comment is not answered and need rebase
@rustbot label: +S-waiting-on-author, -S-waiting-on-review