PackFromVector4ReferenceVsPointer benchmark

tests/ImageSharp.Benchmarks/Color/Bulk/PackFromVector4ReferenceVsPointer.cs

@@ -0,0 +1,74 @@
+namespace ImageSharp.Benchmarks
+{
+    using System.Numerics;
+    using System.Runtime.CompilerServices;
+
+    using BenchmarkDotNet.Attributes;
+
+    using ImageSharp;
+    
+    /// <summary>
+    /// Compares two implementation candidates for general BulkPixelOperations.ToVector4():
+    /// - One iterating with pointers
+    /// - One iterating with ref locals
+    /// </summary>
+    public unsafe class PackFromVector4ReferenceVsPointer
+    {
+        private PinnedBuffer<ImageSharp.Color> destination;
+
+        private PinnedBuffer<Vector4> source;
+
+        [Params(16, 128, 1024)]
+        public int Count { get; set; }
+
+        [Setup]
+        public void Setup()
+        {
+            this.destination = new PinnedBuffer<ImageSharp.Color>(this.Count);
+            this.source = new PinnedBuffer<Vector4>(this.Count * 4);
+        }
+
+        [Cleanup]
+        public void Cleanup()
+        {
+            this.source.Dispose();
+            this.destination.Dispose();
+        }
+
+        [Benchmark(Baseline = true)]
+        public void PackUsingPointers()
+        {
+            Vector4* sp = (Vector4*)this.source.Pointer;
+            byte* dp = (byte*)this.destination.Pointer;
+            int count = this.Count;
+            int size = sizeof(ImageSharp.Color);
+
+            for (int i = 0; i < count; i++)
+            {
+                Vector4 v = Unsafe.Read<Vector4>(sp);
+                ImageSharp.Color c = default(ImageSharp.Color);
+                c.PackFromVector4(v);
+                Unsafe.Write(dp, c);
+
+                sp++;
+                dp += size;
+            }
+        }
+
+        [Benchmark]
+        public void PackUsingReferences()
+        {
+            ref Vector4 sp = ref this.source.Array[0];
+            ref ImageSharp.Color dp = ref this.destination.Array[0];
+            int count = this.Count;
+
+            for (int i = 0; i < count; i++)
+            {
+                dp.PackFromVector4(sp);
+
+                sp = Unsafe.Add(ref sp, 1);
+                dp = Unsafe.Add(ref dp, 1);
+            }
+        }
+    }
+}