Add ConstKind::Expr

[JulianKnodt]

Starting to implement ty::ConstKind::Abstract, most of the match cases are stubbed out, some I was unsure what to add, others I didn't want to add until a more complete implementation was ready.

r? @lcnr

[rustbot]

Some changes occurred to the CTFE / Miri engine

cc @rust-lang/miri

This PR changes MIR

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

Some changes occurred in compiler/rustc_codegen_cranelift

cc @bjorn3

[JulianKnodt]

This will probably require a perf run, considering the size of consts increased, and if there's any alternative way to store consts more efficiently that would also be useful.

[oli-obk]

@bors try @rust-timer queue

[rust-timer]

Awaiting bors try build completion.

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

[bors]

⌛ Trying commit 55f46fc49a77c65c10117d9b412a0061dc2355e5 with merge e5e10c53062b74626dfbbe444c6526d38982715b...

[bors]

☀️ Try build successful - checks-actions
Build commit: e5e10c53062b74626dfbbe444c6526d38982715b (e5e10c53062b74626dfbbe444c6526d38982715b)

[rust-timer]

Queued e5e10c53062b74626dfbbe444c6526d38982715b with parent 2f847b8, future comparison URL.

[rust-timer]

Finished benchmarking commit (e5e10c53062b74626dfbbe444c6526d38982715b): comparison url.

Instruction count

• Primary benchmarks: 🎉 relevant improvements found
• Secondary benchmarks: mixed results

	mean1	max	count2
Regressions 😿 (primary)	N/A	N/A	0
Regressions 😿 (secondary)	2.5%	3.3%	6
Improvements 🎉 (primary)	-0.4%	-0.9%	18
Improvements 🎉 (secondary)	-0.6%	-0.8%	14
All 😿🎉 (primary)	-0.4%	-0.9%	18

Max RSS (memory usage)

Results

• Primary benchmarks: mixed results
• Secondary benchmarks: 🎉 relevant improvements found

	mean1	max	count2
Regressions 😿 (primary)	1.6%	1.6%	1
Regressions 😿 (secondary)	N/A	N/A	0
Improvements 🎉 (primary)	-2.9%	-2.9%	1
Improvements 🎉 (secondary)	-2.1%	-2.4%	2
All 😿🎉 (primary)	-0.6%	-2.9%	2

Cycles

Results

• Primary benchmarks: mixed results
• Secondary benchmarks: 😿 relevant regressions found

	mean1	max	count2
Regressions 😿 (primary)	1.6%	1.8%	2
Regressions 😿 (secondary)	2.9%	3.9%	15
Improvements 🎉 (primary)	-2.6%	-3.1%	2
Improvements 🎉 (secondary)	N/A	N/A	0
All 😿🎉 (primary)	-0.5%	-3.1%	4

If you disagree with this performance assessment, please file an issue in rust-lang/rustc-perf.

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-review -S-waiting-on-perf -perf-regression

Footnotes

1. the arithmetic mean of the percent change↩↩²↩³

2. number of relevant changes↩↩²↩³

[JulianKnodt]

Since the size of the const is the same, I wonder if the perf changes are caused by an increased number of branches, causing it to switch from a jump table to an explicit search?

[BoxyUwU]

@bors r+ rollup=never

[bors]

📌 Commit d0209db has been approved by BoxyUwU

It is now in the queue for this repository.

[bors]

⌛ Testing commit d0209db with merge aff003b...

[bors]

☀️ Test successful - checks-actions
Approved by: BoxyUwU
Pushing aff003b to master...

[rust-timer]

Finished benchmarking commit (aff003b): comparison URL.

Overall result: ❌ regressions - ACTION NEEDED

Next Steps: If you can justify the regressions found in this perf run, please indicate this with @rustbot label: +perf-regression-triaged along with sufficient written justification. If you cannot justify the regressions please open an issue or create a new PR that fixes the regressions, add a comment linking to the newly created issue or PR, and then add the perf-regression-triaged label to this PR.

@rustbot label: +perf-regression
cc @rust-lang/wg-compiler-performance

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)	0.3%	[0.2%, 0.5%]	6
Regressions ❌ (secondary)	0.9%	[0.3%, 1.6%]	21
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.2%	[-0.2%, -0.2%]	1
All ❌✅ (primary)	0.3%	[0.2%, 0.5%]	6

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
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-3.4%	[-5.5%, -2.2%]	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)	7.7%	[6.4%, 9.1%]	6
Improvements ✅ (primary)	-1.2%	[-1.8%, -0.8%]	21
Improvements ✅ (secondary)	-3.1%	[-4.6%, -1.3%]	14
All ❌✅ (primary)	-1.2%	[-1.8%, -0.8%]	21

[nnethercote]

Previous perf runs showed slight improvements, but the post-merge one shows regressions. They are mostly among secondary benchmarks.