Removed redundant bounds checking at Split's next and next_back methods

[lch361]

Since these methods are using Iterator::rposition, which always returns a valid index, then there is no point in regular indexing with bounds checking

[rustbot]

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[the8472]

The optimizer is often able to eliminate bounds checks based on value range information. Have you checked the assembly whether this makes any difference?

[lch361]

The optimizer is often able to eliminate bounds checks based on value range information. Have you checked the assembly whether this makes any difference?

Well, I guess sometimes it fails to eliminate bound checks. I was compiling my project which uses Split with:
rustc 1.77.0-nightly (2d7be73 2023-12-23)
codegen-units = 1
opt-level = 2
lto = "fat"
And noticed that panicking code still was appearing in assembly

[the8472]

Might affect perf.

@bors r+ rollup=never

[bors]

📌 Commit c082c1c has been approved by the8472

It is now in the queue for this repository.

[bors]

⌛ Testing commit c082c1c with merge f645628...

[bors]

☀️ Test successful - checks-actions
Approved by: the8472
Pushing f645628 to master...

[rust-timer]

Finished benchmarking commit (f645628): 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)

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)	2.6%	[1.3%, 3.7%]	3
Improvements ✅ (primary)	-4.2%	[-5.7%, -2.8%]	2
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-4.2%	[-5.7%, -2.8%]	2

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)	2.9%	[2.3%, 3.3%]	4
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Binary size

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)	0.0%	[0.0%, 0.0%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.0%	[0.0%, 0.0%]	1

Bootstrap: 671.757s -> 671.254s (-0.07%)
Artifact size: 312.54 MiB -> 312.53 MiB (-0.00%)