Optimize Enumerable.Min/Max<T> for value types with Comparer<T>.Default intrinsic

[stephentoub]

Method	Toolchain	Count	Mean	Ratio
Max	\master\corerun.exe	10	70.12 ns	1.00
Max	\pr\corerun.exe	10	56.19 ns	0.80
Min	\master\corerun.exe	10	67.45 ns	1.00
Min	\pr\corerun.exe	10	54.85 ns	0.81
Max	\master\corerun.exe	1000000	6,007,980.36 ns	1.00
Max	\pr\corerun.exe	1000000	4,666,923.86 ns	0.78
Min	\master\corerun.exe	1000000	5,492,475.28 ns	1.00
Min	\pr\corerun.exe	1000000	4,401,151.26 ns	0.80

[Params(10, 1_000_000)]
public int Count { get; set; }

[GlobalSetup]
public void Setup()
{
    var r = new Random();
    _times = Enumerable.Range(0, Count).Select(_ => TimeSpan.FromMilliseconds(r.Next(0, int.MaxValue))).ToArray();
}

private TimeSpan[] _times;

[Benchmark]
public TimeSpan Max() => _times.Max();
[Benchmark]
public TimeSpan Min() => _times.Min();

[ghost]

Tagging subscribers to this area: @eiriktsarpalis
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Issue Details

---

Method	Toolchain	Count	Mean	Ratio
Max	\master\corerun.exe	10	70.12 ns	1.00
Max	\pr\corerun.exe	10	56.19 ns	0.80
Min	\master\corerun.exe	10	67.45 ns	1.00
Min	\pr\corerun.exe	10	54.85 ns	0.81
Max	\master\corerun.exe	1000000	6,007,980.36 ns	1.00
Max	\pr\corerun.exe	1000000	4,666,923.86 ns	0.78
Min	\master\corerun.exe	1000000	5,492,475.28 ns	1.00
Min	\pr\corerun.exe	1000000	4,401,151.26 ns	0.80

[Params(10, 1_000_000)]
public int Count { get; set; }

[GlobalSetup]
public void Setup()
{
    var r = new Random();
    _times = Enumerable.Range(0, Count).Select(_ => TimeSpan.FromMilliseconds(r.Next(0, int.MaxValue))).ToArray();
}

private TimeSpan[] _times;

[Benchmark]
public TimeSpan Max() => _times.Max();
[Benchmark]
public TimeSpan Min() => _times.Min();

Author:	stephentoub
Assignees:	-
Labels:	area-System.Linq
Milestone:	-

[stephentoub]

Thanks, @EgorBo ;-)

[mburbea]

What about optimizing the case for TResult Max(IEnumerable<TSource>, Func<TSource, TResult>)?

[stephentoub]

What about optimizing the case for TResult Max(IEnumerable<TSource>, Func<TSource, TResult>)?

#48289

[eiriktsarpalis]

Out of curiosity, what is the motivation for not optimizing reference types?

[mburbea]

See issue #10050 for more details