Expose IsSupported properties on the vector types

[tannergooding]

Summary

There are currently several scenarios where we may be dealing with a generic type and want to vectorize it if vectorization support exists. However, those checks are currently sometimes hard to do, may not cover future changes to what T is supported, and may not be constant folded by the JIT.

One such example of this is in #68183 where we currently have to limit the vectorization paths after checking for specific cases of T.

Users would be expected to check both Vector128<T>.IsSupported && Vector128.IsHardwareAccelerated to determine if the usage of T is expected to be performant.

API Proposal

namespace System.Numerics
{
    public partial struct Vector<T>
    {
        public static bool IsSupported { get; }
    }
}

namespace System.Runtime.Intrinsics
{
    public partial struct Vector64<T>
    {
        public static bool IsSupported { get; }
    }

    public partial struct Vector128<T>
    {
        public static bool IsSupported { get; }
    }

    public partial struct Vector256<T>
    {
        public static bool IsSupported { get; }
    }
}

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Issue Details

---

Summary

There are currently several scenarios where we may be dealing with a generic type and want to vectorize it if vectorization support exists. However, those checks are currently sometimes hard to do, may not cover future changes to what T is supported, and may not be constant folded by the JIT.

One such example of this is in #68183 where we currently have to limit the vectorization paths after checking for specific cases of T.

Users would be expected to check both Vector128<T>.IsSupported && Vector128.IsHardwareAccelerated to determine if the usage of T is expected to be performant.

API Proposal

namespace System.Numerics
{
    public partial struct Vector<T>
    {
        public static bool IsSupported { get; }
    }
}

namespace System.Runtime.Intrinsics
{
    public partial struct Vector64<T>
    {
        public static bool IsSupported { get; }
    }

    public partial struct Vector128<T>
    {
        public static bool IsSupported { get; }
    }

    public partial struct Vector256<T>
    {
        public static bool IsSupported { get; }
    }
}

Author:	tannergooding
Assignees:	-
Labels:	area-System.Runtime.Intrinsics, api-ready-for-review
Milestone:	-

[tannergooding]

CC. @stephentoub

[terrajobst]

Video

• Looks good as proposed

namespace System.Numerics;

public partial struct Vector<T>
{
    public static bool IsSupported { get; }
}

namespace System.Runtime.Intrinsics;

public partial struct Vector64<T>
{
    public static bool IsSupported { get; }
}

public partial struct Vector128<T>
{
    public static bool IsSupported { get; }
}

public partial struct Vector256<T>
{
    public static bool IsSupported { get; }
}