consistently pass ty::Const through valtrees

[RalfJung]

Some drive-by things extracted from #115748.

[rustbot]

r? @davidtwco

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[RalfJung]

I rebased over #115803 and made this PR the logical next step -- consistently pass all ty::Const through valtrees, never short-cutting directly to a ConstValue.
r? @oli-obk

Let's see what perf says.
@bors try @rust-timer queue

[bors]

⌛ Trying commit 19fb2c7 with merge c7767b6...

[bors]

☀️ Try build successful - checks-actions
Build commit: c7767b6 (c7767b6312f5cbb95ff4830dae8fa940221f9f30)

[bors]

☀️ Try build successful - checks-actions
Build commit: c7767b6 (c7767b6312f5cbb95ff4830dae8fa940221f9f30)

[rust-timer]

Finished benchmarking commit (c7767b6): 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

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)	-2.5%	[-2.5%, -2.5%]	1
Improvements ✅ (secondary)	-0.6%	[-0.6%, -0.6%]	2
All ❌✅ (primary)	-2.5%	[-2.5%, -2.5%]	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: 631.545s -> 631.288s (-0.04%)
Artifact size: 317.98 MiB -> 318.00 MiB (0.01%)

[RalfJung]

That looks promising. :)

[oli-obk]

@bors r+

[bors]

📌 Commit 19fb2c7 has been approved by oli-obk

It is now in the queue for this repository.

[bors]

⌛ Testing commit 19fb2c7 with merge e437e57...

[bors]

☀️ Test successful - checks-actions
Approved by: oli-obk
Pushing e437e57 to master...

[rust-timer]

Finished benchmarking commit (e437e57): comparison URL.

Overall result: no relevant changes - no action needed

@rustbot label: -perf-regression

Instruction count

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

Max RSS (memory usage)

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

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)	-	-	0
Improvements ✅ (primary)	-5.1%	[-5.1%, -5.1%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-5.1%	[-5.1%, -5.1%]	1

Binary size

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

Bootstrap: 630.976s -> 632.742s (0.28%)
Artifact size: 317.91 MiB -> 318.05 MiB (0.05%)