Extract all instance shim variants into new ShimKind enum

[camelid]

They tend to have similar handling -- e.g., they should be the only
input to the mir_shims query -- so it's cleaner to group them
together. This will also make potential future refactorings easier, such
as only carrying GenericArgsRef for instances that actually use it
(e.g., Item) but not others (e.g., CloneShim).

cc https://rust-lang.zulipchat.com/#narrow/channel/131828-t-compiler/topic/moving.20ty.3A.3AInstance.2Eargs.20into.20ty.3A.3AInstanceKind.20variants
r? @oli-obk

[rustbot]

rustc_codegen_cranelift is developed in its own repository. If possible, consider making this change to rust-lang/rustc_codegen_cranelift instead.

cc @bjorn3

Some changes occurred in compiler/rustc_sanitizers

cc @rcvalle

Some changes occurred to the CTFE / Miri interpreter

cc @rust-lang/miri

This PR changes rustc_public

cc @oli-obk, @celinval, @ouz-a, @makai410

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

Some changes occurred to the CTFE machinery

cc @RalfJung, @oli-obk, @lcnr

[camelid]

Not sure if this should get an MCP; let me know.

[rustbot]

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

[oli-obk]

since it touches a fairly often called query and data structure, let's perf it first

@bors try @rust-timer queue

r=me with that clean or green

[rust-bors]

☀️ Try build successful (CI)
Build commit: d347081 (d34708186d2a5b4ccbd9bb66475a209f31661214)
Base parent: cddcbec (cddcbec198760511240bf0e728193bf4d700acb4)

[rust-timer]

Finished benchmarking commit (d347081): comparison URL.

Overall result: ❌ regressions - no action needed

Benchmarking means the PR may be perf-sensitive. Consider adding rollup=never if this change is not fit for rolling up.

@rustbot label: -S-waiting-on-perf -perf-regression

Instruction count

Our most reliable metric. Used to determine the overall result above. However, even this metric can be noisy.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	0.5%	[0.5%, 0.5%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary -2.6%, secondary -2.3%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-2.6%	[-2.9%, -2.4%]	2
Improvements ✅ (secondary)	-2.3%	[-2.3%, -2.3%]	1
All ❌✅ (primary)	-2.6%	[-2.9%, -2.4%]	2

Cycles

Results (primary -0.2%, secondary 2.3%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	2.3%	[2.3%, 2.3%]	1
Regressions ❌ (secondary)	4.0%	[3.3%, 4.7%]	4
Improvements ✅ (primary)	-1.5%	[-1.8%, -1.2%]	2
Improvements ✅ (secondary)	-4.5%	[-4.5%, -4.5%]	1
All ❌✅ (primary)	-0.2%	[-1.8%, 2.3%]	3

Binary size

Results (secondary 0.0%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	0.0%	[0.0%, 0.0%]	8
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Bootstrap: 505.379s -> 508.681s (0.65%)
Artifact size: 353.06 MiB -> 353.25 MiB (0.05%)

[camelid]

Perf looks good, just a small regression on one scenario for a secondary benchmark. Also fixed the commit history.

@bors r=oli-obk

[rust-bors]

📌 Commit d06469a has been approved by oli-obk

It is now in the queue for this repository.

🌲 The tree is currently closed for pull requests below priority 5. This pull request will be tested once the tree is reopened.