Add remaining set of TensorPrimitives APIs for .NET 8 (dotnet#92154)

* Add remaining set of TensorPrimitives APIs for .NET 8

Adds non-vectorized implementations of:
- Max
- Min
- MaxMagnitude
- MinMagnitude
- IndexOfMax
- IndexOfMin
- IndexOfMaxMagnitude
- ConvertToHalf (only on .NET Core)
- ConvertToSingle (only on .NET Core)
- IndexOfMinMagnitude

Adds vectorized implementations of:
- Sum
- SumOfSquares
- SumOfMagnitudes
- Product
- ProductOfSums
- ProductOfDifferences

Also includes the helpers that'll make it trivial to vectorize Dot.

Beyond vectorizing the non-vectorized ones, the vectorized implementations should be improved further, including:
- Handling alignment better
- Vectorizing the remainder that doesn't fit in a vector rather than falling back to scalar

* Cleanup after previous PR, vectorize CosineSimilarity/Dot/L2Normalize/Distance, add tests

* Address PR feedback, and fix a few other issues

src/coreclr/jit/utils.cpp

@@ -2734,7 +2734,7 @@ float FloatingPointUtils::maximumNumber(float x, float y)
 //
 // It propagates NaN inputs back to the caller and
 // otherwise returns the lesser of the inputs. It
-// treats +0 as lesser than -0 as per the specification.
+// treats +0 as greater than -0 as per the specification.
 //
 // Arguments:
 //    val1 - left operand
@@ -2763,7 +2763,7 @@ double FloatingPointUtils::minimum(double val1, double val2)
 //
 // It propagates NaN inputs back to the caller and
 // otherwise returns the input with a lesser magnitude.
-// It treats +0 as lesser than -0 as per the specification.
+// It treats +0 as greater than -0 as per the specification.
 //
 // Arguments:
 //    x - left operand
@@ -2856,7 +2856,7 @@ double FloatingPointUtils::minimumNumber(double x, double y)
 //
 // It propagates NaN inputs back to the caller and
 // otherwise returns the lesser of the inputs. It
-// treats +0 as lesser than -0 as per the specification.
+// treats +0 as greater than -0 as per the specification.
 //
 // Arguments:
 //    val1 - left operand
@@ -2885,7 +2885,7 @@ float FloatingPointUtils::minimum(float val1, float val2)
 //
 // It propagates NaN inputs back to the caller and
 // otherwise returns the input with a lesser magnitude.
-// It treats +0 as lesser than -0 as per the specification.
+// It treats +0 as greater than -0 as per the specification.
 //
 // Arguments:
 //    x - left operand

src/libraries/Common/tests/TestUtilities/System/Buffers/BoundedMemory.Unix.cs

@@ -30,6 +30,8 @@ public UnixImplementation(int elementCount)
 
             public override bool IsReadonly => false;
 
+            public override int Length => _elementCount;
+
             public override Memory<T> Memory => _memoryManager.Memory;
 
             public override Span<T> Span
@@ -83,10 +85,7 @@ protected override void Dispose(bool disposing)
                     // no-op; the handle will be disposed separately
                 }
 
-                public override Span<T> GetSpan()
-                {
-                    throw new NotImplementedException();
-                }
+                public override Span<T> GetSpan() => _impl.Span;
 
                 public override MemoryHandle Pin(int elementIndex)
                 {

src/libraries/Common/tests/TestUtilities/System/Buffers/BoundedMemory.Windows.cs

@@ -81,6 +81,8 @@ internal WindowsImplementation(VirtualAllocHandle handle, int byteOffsetIntoHand
 
             public override bool IsReadonly => (Protection != VirtualAllocProtection.PAGE_READWRITE);
 
+            public override int Length => _elementCount;
+
             internal VirtualAllocProtection Protection
             {
                 get
@@ -189,10 +191,7 @@ protected override void Dispose(bool disposing)
                     // no-op; the handle will be disposed separately
                 }
 
-                public override Span<T> GetSpan()
-                {
-                    throw new NotImplementedException();
-                }
+                public override Span<T> GetSpan() => _impl.Span;
 
                 public override MemoryHandle Pin(int elementIndex)
                 {

src/libraries/Common/tests/TestUtilities/System/Buffers/BoundedMemory.cs

@@ -14,6 +14,9 @@ public abstract class BoundedMemory<T> : IDisposable where T : unmanaged
         /// </summary>
         public abstract bool IsReadonly { get; }
 
+        /// <summary>Gets the length of the <see cref="BoundedMemory{T}"/> instance.</summary>
+        public abstract int Length { get; }
+
         /// <summary>
         /// Gets the <see cref="Memory{Byte}"/> which represents this native memory.
         /// This <see cref="BoundedMemory{T}"/> instance must be kept alive while working with the <see cref="Memory{Byte}"/>.
@@ -44,5 +47,23 @@ public abstract class BoundedMemory<T> : IDisposable where T : unmanaged
         /// OS does not support marking the memory block as read+write.
         /// </summary>
         public abstract void MakeWriteable();
+
+        /// <summary>
+        /// Gets the <see cref="Span{Byte}"/> which represents this native memory.
+        /// This <see cref="BoundedMemory{T}"/> instance must be kept alive while working with the <see cref="Span{Byte}"/>.
+        /// </summary>
+        public static implicit operator Span<T>(BoundedMemory<T> boundedMemory) => boundedMemory.Span;
+
+        /// <summary>
+        /// Gets the <see cref="ReadOnlySpan{Byte}"/> which represents this native memory.
+        /// This <see cref="BoundedMemory{T}"/> instance must be kept alive while working with the <see cref="ReadOnlySpan{Byte}"/>.
+        /// </summary>
+        public static implicit operator ReadOnlySpan<T>(BoundedMemory<T> boundedMemory) => boundedMemory.Span;
+
+        /// <summary>
+        /// Gets a reference to the element at the specified index.
+        /// This <see cref="BoundedMemory{T}"/> instance must be kept alive while working with the reference.
+        /// </summary>
+        public ref T this[int index] => ref Span[index];
     }
 }

src/libraries/System.Numerics.Tensors/ref/System.Numerics.Tensors.cs

@@ -20,19 +20,33 @@ public static void Divide(System.ReadOnlySpan<float> x, System.ReadOnlySpan<floa
         public static void Divide(System.ReadOnlySpan<float> x, float y, System.Span<float> destination) { }
         public static float Dot(System.ReadOnlySpan<float> x, System.ReadOnlySpan<float> y) { throw null; }
         public static void Exp(System.ReadOnlySpan<float> x, System.Span<float> destination) { }
+        public static int IndexOfMax(System.ReadOnlySpan<float> x) { throw null; }
+        public static int IndexOfMaxMagnitude(System.ReadOnlySpan<float> x) { throw null; }
+        public static int IndexOfMin(System.ReadOnlySpan<float> x) { throw null; }
+        public static int IndexOfMinMagnitude(System.ReadOnlySpan<float> x) { throw null; }
         public static float L2Normalize(System.ReadOnlySpan<float> x) { throw null; }
         public static void Log(System.ReadOnlySpan<float> x, System.Span<float> destination) { }
+        public static float Max(System.ReadOnlySpan<float> x) { throw null; }
+        public static float MaxMagnitude(System.ReadOnlySpan<float> x) { throw null; }
+        public static float Min(System.ReadOnlySpan<float> x) { throw null; }
+        public static float MinMagnitude(System.ReadOnlySpan<float> x) { throw null; }
         public static void Multiply(System.ReadOnlySpan<float> x, System.ReadOnlySpan<float> y, System.Span<float> destination) { }
         public static void Multiply(System.ReadOnlySpan<float> x, float y, System.Span<float> destination) { }
         public static void MultiplyAdd(System.ReadOnlySpan<float> x, System.ReadOnlySpan<float> y, System.ReadOnlySpan<float> addend, System.Span<float> destination) { }
         public static void MultiplyAdd(System.ReadOnlySpan<float> x, System.ReadOnlySpan<float> y, float addend, System.Span<float> destination) { }
         public static void MultiplyAdd(System.ReadOnlySpan<float> x, float y, System.ReadOnlySpan<float> addend, System.Span<float> destination) { }
         public static void Negate(System.ReadOnlySpan<float> x, System.Span<float> destination) { }
+        public static float Product(System.ReadOnlySpan<float> x) { throw null; }
+        public static float ProductOfDifferences(System.ReadOnlySpan<float> x, System.ReadOnlySpan<float> y) { throw null; }
+        public static float ProductOfSums(System.ReadOnlySpan<float> x, System.ReadOnlySpan<float> y) { throw null; }
         public static void Sigmoid(System.ReadOnlySpan<float> x, System.Span<float> destination) { }
         public static void Sinh(System.ReadOnlySpan<float> x, System.Span<float> destination) { }
         public static void SoftMax(System.ReadOnlySpan<float> x, System.Span<float> destination) { }
         public static void Subtract(System.ReadOnlySpan<float> x, System.ReadOnlySpan<float> y, System.Span<float> destination) { }
         public static void Subtract(System.ReadOnlySpan<float> x, float y, System.Span<float> destination) { }
+        public static float Sum(System.ReadOnlySpan<float> x) { throw null; }
+        public static float SumOfMagnitudes(System.ReadOnlySpan<float> x) { throw null; }
+        public static float SumOfSquares(System.ReadOnlySpan<float> x) { throw null; }
         public static void Tanh(System.ReadOnlySpan<float> x, System.Span<float> destination) { }
     }
 }

src/libraries/System.Numerics.Tensors/ref/System.Numerics.Tensors.csproj

@@ -8,6 +8,10 @@
     <Compile Include="System.Numerics.Tensors.cs" />
   </ItemGroup>
 
+  <ItemGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETCoreApp'">
+    <Compile Include="System.Numerics.Tensors.netcore.cs" />
+  </ItemGroup>
+
   <ItemGroup Condition="'$(TargetFrameworkIdentifier)' != '.NETCoreApp'">
     <PackageReference Include="System.Memory" Version="$(SystemMemoryVersion)" />
   </ItemGroup>

src/libraries/System.Numerics.Tensors/ref/System.Numerics.Tensors.netcore.cs

@@ -0,0 +1,14 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// ------------------------------------------------------------------------------
+// Changes to this file must follow the https://aka.ms/api-review process.
+// ------------------------------------------------------------------------------
+
+namespace System.Numerics.Tensors
+{
+    public static partial class TensorPrimitives
+    {
+        public static void ConvertToHalf(System.ReadOnlySpan<float> source, System.Span<System.Half> destination) { throw null; }
+        public static void ConvertToSingle(System.ReadOnlySpan<System.Half> source, System.Span<float> destination) { throw null; }
+    }
+}