Memory alignment benchmarks

Benchmarks/MemoryAlignment/AddArrays.cs

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+
+using BenchmarkDotNet.Attributes;
+using System.Runtime.InteropServices;
+using System.Runtime.Intrinsics;
+using System.Runtime.Intrinsics.X86;
+
+public unsafe class AddArrays
+{
+    private static T* Allocate<T>(int elemCount, int offsetFromAligned) where T : unmanaged
+    {
+        var toalloc = (nuint)(elemCount * sizeof(T) + offsetFromAligned);
+        return (T*)((byte*)NativeMemory.AlignedAlloc(toalloc, 64) + offsetFromAligned);
+    }
+
+    [Params(0x1000)]
+    public int ElemCount;
+
+    [Params(0,  1,  2,  3,  4,  5,  6,  7,  8,  9,  10, 11, 12, 13, 14, 15,
+            16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31,
+            32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47,
+            48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63)]
+    public int Offset;
+
+    private int* a;
+    private int* b;
+    private int* c;
+
+    [GlobalSetup]
+    public void Setup()
+    {
+        a = Allocate<int>(ElemCount, Offset);
+        b = Allocate<int>(ElemCount, Offset);
+        c = Allocate<int>(ElemCount, Offset);
+        var rand = new Random(100);
+        for (int i = 0; i < ElemCount; i++)
+        {
+            a[i] = rand.Next();
+            b[i] = rand.Next();
+        }
+    }
+
+    /*
+    [Benchmark]
+    public int NaiveAdd()
+    {
+        var e = ElemCount;
+        for (int i = 0; i < e; i++)
+            c[i] = a[i] + b[i];
+        return c[Math.Abs(a[0] + b[e / 2]) % e];
+    }*/
+
+    [Benchmark]
+    public int SimdAdd()
+    {
+        var e = ElemCount;
+        for (int i = 0; i < e; i += Vector256<int>.Count)
+        {
+            var av = Avx2.LoadVector256(a + i);
+            var bv = Avx2.LoadVector256(b + i);
+            Avx2.Store(c + i, Avx2.Add(av, bv));
+        }
+        return c[Math.Abs(a[0] + b[e / 2]) % e];
+    }
+}

Benchmarks/MemoryAlignment/MemoryAlignment.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net6.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+    <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="BenchmarkDotNet" Version="0.13.0" />
+  </ItemGroup>
+
+</Project>

Benchmarks/MemoryAlignment/Program.cs

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+/*
+var b = new AddArrays();
+
+b.ElemCount = 0x10;
+b.Offset = 0;
+b.Setup();
+Console.WriteLine(b.NaiveAdd());
+Console.WriteLine(b.SimdAdd());
+
+b.ElemCount = 0x10;
+b.Offset = 46;
+b.Setup();
+Console.WriteLine(b.NaiveAdd());
+Console.WriteLine(b.SimdAdd());
+*/
+
+using BenchmarkDotNet.Running;
+
+BenchmarkRunner.Run<AddArrays>();