[DO NOT MERGE] Store THIR patterns in Arc instead of Box

[Zalathar]

(Checking if this has any measurable effect on perf.)

r? ghost
@rustbot experimental

[rustbot]

Some changes occurred in rustc_ty_utils::consts.rs

cc @BoxyUwU

Some changes occurred in match checking

cc @Nadrieril

Some changes occurred in exhaustiveness checking

cc @Nadrieril

[Zalathar]

@bors try @rust-timer queue

[bors]

⌛ Trying commit 0201b00 with merge ac7601f83319191e022cff963ad437230fb27043...

[bors]

☀️ Try build successful - checks-actions
Build commit: ac7601f (ac7601f83319191e022cff963ad437230fb27043)

[rust-timer]

Finished benchmarking commit (ac7601f): comparison URL.

Overall result: ❌ regressions - 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 the most reliable metric that we have; it was used to determine the overall result at the top of this comment. However, even this metric can sometimes exhibit noise.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	0.1%	[0.1%, 0.1%]	4
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary -0.6%, secondary 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)	2.9%	[2.9%, 2.9%]	1
Regressions ❌ (secondary)	1.5%	[1.5%, 1.5%]	1
Improvements ✅ (primary)	-2.3%	[-2.9%, -1.7%]	2
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-0.6%	[-2.9%, 2.9%]	3

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: 777.275s -> 777.712s (0.06%)
Artifact size: 328.69 MiB -> 328.70 MiB (0.01%)

[Zalathar]

I've proposed some less ambitious changes in #136435.