Use codegen_select in vtable_trait_upcasting_coercion_new_vptr_slot

[compiler-errors]

A super tiny clean up

[rustbot]

r? @nagisa

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[compiler-errors]

@bors try @rust-timer queue

[rust-timer]

Awaiting bors try build completion.

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

[bors]

⌛ Trying commit 20bb56e with merge 62d84d6d284f82beb42154f057d565e919196a63...

[bors]

☀️ Try build successful - checks-actions
Build commit: 62d84d6d284f82beb42154f057d565e919196a63 (62d84d6d284f82beb42154f057d565e919196a63)

[rust-timer]

Queued 62d84d6d284f82beb42154f057d565e919196a63 with parent 11ebe65, future comparison URL.

[compiler-errors]

Rust-timer didnt respond but the perf results came back neutral: https://perf.rust-lang.org/compare.html?start=11ebe6512b4c77633c59f8dcdd421df3b79d1a9f&end=62d84d6d284f82beb42154f057d565e919196a63

[nagisa]

@bors r+

Looks okay to me. I’m not 100% familiar with this code, but given that vtable_trait_upcasting_coercion_new_vptr_slot is called from codegen only, this seems like an appropriate use of codegen_select_candidate.

That said, although the perf results came out neutral, codegen_select_candidate seems to be doing a bunch more. I suspect we're just not exercising this code path much, so if there was an actual regression, it would be hard to see here. Which I guess is fine either way – if the code path is not exercised much, we probably shouldn’t worry about small perf differences for that code anyway.

[bors]

📌 Commit 20bb56e has been approved by nagisa

It is now in the queue for this repository.

[bors]

⌛ Testing commit 20bb56e with merge 1e1e5b8...

[bors]

☀️ Test successful - checks-actions
Approved by: nagisa
Pushing 1e1e5b8 to master...

[rust-timer]

Finished benchmarking commit (1e1e5b8): comparison URL.

Overall result: ❌ regressions - no action needed

@rustbot label: -perf-regression

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)	0.4%	[0.4%, 0.5%]	2
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.4%	[0.4%, 0.5%]	2

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)	0.9%	[0.9%, 0.9%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.9%	[0.9%, 0.9%]	1

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)	0.6%	[0.6%, 0.6%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.6%	[0.6%, 0.6%]	1