Specialize by length in single-value SearchValues<string>

[MihaZupan]

Fixes #96142 - pretty much a revert of 2e70415 from #88394.

Method	Toolchain	Word	Mean	Error	Ratio
Count	main	the	146.1 us	2.83 us	1.00
Count	pr	the	119.7 us	0.96 us	0.82
CountIgnoreCase	main	the	169.5 us	2.99 us	1.00
CountIgnoreCase	pr	the	150.4 us	0.51 us	0.89
Count	main	that	71.10 us	0.229 us	1.00
Count	pr	that	62.66 us	0.237 us	0.88
CountIgnoreCase	main	that	79.90 us	0.197 us	1.00
CountIgnoreCase	pr	that	74.46 us	1.221 us	0.93
Count	main	Holmes	49.58 us	0.151 us	1.00
Count	pr	Holmes	48.54 us	0.663 us	0.98
CountIgnoreCase	main	Holmes	59.90 us	0.126 us	1.00
CountIgnoreCase	pr	Holmes	59.95 us	0.623 us	1.00
Count	main	something	44.72 us	0.281 us	1.00
Count	pr	something	44.10 us	0.331 us	0.99
CountIgnoreCase	main	something	54.12 us	0.221 us	1.00
CountIgnoreCase	pr	something	54.59 us	0.106 us	1.01

---

Looking at the benchmark from #96142

Method	Toolchain	Mean	Error	Ratio
RegularCaseInsensitive	main	26.12 ns	0.195 ns	1.00
RegularCaseInsensitive	pr	25.43 ns	0.366 ns	0.97
OptimizedCaseInsensitive	main	56.46 ns	0.770 ns	1.00
OptimizedCaseInsensitive	pr	20.72 ns	0.337 ns	0.37
RegularCaseSensitive	main	13.95 ns	0.114 ns	1.00
RegularCaseSensitive	pr	14.10 ns	0.179 ns	1.01
OptimizedCaseSensitive	main	56.65 ns	0.850 ns	1.00
OptimizedCaseSensitive	pr	10.38 ns	0.174 ns	0.18

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Issue Details

---

Fixes #96142 - pretty much a revert of 2e70415 from #88394.

Method	Toolchain	Word	Mean	Error	Ratio
Count	main	the	146.1 us	2.83 us	1.00
Count	pr	the	119.7 us	0.96 us	0.82
CountIgnoreCase	main	the	169.5 us	2.99 us	1.00
CountIgnoreCase	pr	the	150.4 us	0.51 us	0.89
Count	main	that	71.10 us	0.229 us	1.00
Count	pr	that	62.66 us	0.237 us	0.88
CountIgnoreCase	main	that	79.90 us	0.197 us	1.00
CountIgnoreCase	pr	that	74.46 us	1.221 us	0.93
Count	main	Holmes	49.58 us	0.151 us	1.00
Count	pr	Holmes	48.54 us	0.663 us	0.98
CountIgnoreCase	main	Holmes	59.90 us	0.126 us	1.00
CountIgnoreCase	pr	Holmes	59.95 us	0.623 us	1.00
Count	main	something	44.72 us	0.281 us	1.00
Count	pr	something	44.10 us	0.331 us	0.99
CountIgnoreCase	main	something	54.12 us	0.221 us	1.00
CountIgnoreCase	pr	something	54.59 us	0.106 us	1.01

---

Looking at the benchmark from #96142

Method	Toolchain	Mean	Error	Ratio
RegularCaseInsensitive	main	26.12 ns	0.195 ns	1.00
RegularCaseInsensitive	pr	25.43 ns	0.366 ns	0.97
OptimizedCaseInsensitive	main	56.46 ns	0.770 ns	1.00
OptimizedCaseInsensitive	pr	20.72 ns	0.337 ns	0.37
RegularCaseSensitive	main	13.95 ns	0.114 ns	1.00
RegularCaseSensitive	pr	14.10 ns	0.179 ns	1.01
OptimizedCaseSensitive	main	56.65 ns	0.850 ns	1.00
OptimizedCaseSensitive	pr	10.38 ns	0.174 ns	0.18

Author:	MihaZupan
Assignees:	MihaZupan
Labels:	area-System.Buffers
Milestone:	9.0.0

[stephentoub]

Thanks!