Ergonomic ref counting: optimize away clones when possible

[spastorino]

This PR build on top of #134797. It optimizes codegen of ergonomic ref-counting when the type being used is only known to be copy after monomorphization. We avoid codening a clone and generate bitwise copy instead.

RFC: rust-lang/rfcs#3680
Tracking issue: #132290
Project goal: rust-lang/rust-project-goals#107

r? @nikomatsakis

This PR could better sit on top of #131650 but as it did not land yet I've decided to just do minimal changes. It may be the case that doing what I'm doing regress the performance and we may need to go the full route of #131650.
cc @saethlin in this regard.

[spastorino]

We need to clone the mir body here, unsure how bad this could be.

[spastorino]

Would need to properly decide exactly what to do with this test. If just removing it is fine or if there's some variation that needs to be placed in tests/ui. Didn't bother to check this for now.

[rustbot]

This PR changes a file inside tests/crashes. If a crash was fixed, please move into the corresponding ui subdir and add 'Fixes #' to the PR description to autoclose the issue upon merge.

This PR changes MIR

cc @oli-obk, @RalfJung, @JakobDegen, @davidtwco, @vakaras

Some changes occurred in compiler/rustc_codegen_ssa

cc @WaffleLapkin

Some changes occurred in src/tools/clippy

cc @rust-lang/clippy

[RalfJung]

(Procedurally, it'd be nice to reference the tracking issue in every PR related to that feature. Makes it much easier to navigate around for someone who's not following every single PR in this project.)

[spastorino]

@bors try @rust-timer queue

[bors]

⌛ Trying commit da1df90 with merge c5e50d7...

[bors]

☀️ Try build successful - checks-actions
Build commit: c5e50d7 (c5e50d7174504206bc4cc4c002f3a3cde8b5cbb3)

[rust-timer]

Finished benchmarking commit (c5e50d7): comparison URL.

Overall result: ❌✅ regressions and improvements - please read the text below

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.

Next Steps: If you can justify the regressions found in this try perf run, please indicate this with @rustbot label: +perf-regression-triaged along with sufficient written justification. If you cannot justify the regressions please fix the regressions and do another perf run. If the next run shows neutral or positive results, the label will be automatically removed.

@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)	0.6%	[0.2%, 1.3%]	36
Regressions ❌ (secondary)	3.1%	[0.2%, 18.5%]	7
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.1%	[-0.2%, -0.1%]	4
All ❌✅ (primary)	0.6%	[0.2%, 1.3%]	36

Max RSS (memory usage)

Results (primary 8.1%, secondary 1.1%)

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)	8.1%	[2.2%, 29.5%]	42
Regressions ❌ (secondary)	3.1%	[2.9%, 3.4%]	3
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.0%	[-2.4%, -1.5%]	2
All ❌✅ (primary)	8.1%	[2.2%, 29.5%]	42

Cycles

Results (primary 1.5%, secondary 3.8%)

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%	[0.9%, 2.0%]	11
Regressions ❌ (secondary)	5.7%	[1.4%, 18.3%]	4
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-3.7%	[-3.7%, -3.7%]	1
All ❌✅ (primary)	1.5%	[0.9%, 2.0%]	11

Binary size

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

Bootstrap: 774.818s -> 781.377s (0.85%)
Artifact size: 365.93 MiB -> 366.03 MiB (0.03%)