testcase for RAW mask byte

Author: dhartglassMSFT

src/tests/JIT/HardwareIntrinsics/Arm/Sve2/CreateWhileRWMask.cs

@@ -0,0 +1,65 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.Numerics;
+using System.Runtime.CompilerServices;
+using System.Runtime.Intrinsics;
+using System.Runtime.Intrinsics.Arm;
+using Xunit;
+
+namespace JIT.HardwareIntrinsics.Arm._Sve2
+{
+    public static partial class Program
+    {
+        [Fact]
+        public static unsafe void CreateWhileReadAfterWriteMaskByte_SameAddress()
+        {
+            if (!Sve2.IsSupported)
+            {
+                return;
+            }
+
+            // When pointers are idential, all elements of returned mask are "1"
+            byte* ptr = stackalloc byte[Vector<byte>.Count];
+            Vector<byte> mask = Sve2.CreateWhileReadAfterWriteMaskByte(ptr, ptr);
+
+            for (int i = 0; i < Vector<byte>.Count; i++)
+            {
+                if (mask.GetElement(i) == 0)
+                {
+                    throw new Exception(
+                        $"CreateWhileReadAfterWriteMaskByte(ptr, ptr): Expected all elements true, but element {i} was false.");
+                }
+            }
+        }
+
+        [Fact]
+        public static unsafe void CreateWhileReadAfterWriteMaskByte_OffsetByOne()
+        {
+            if (!Sve2.IsSupported)
+            {
+                return;
+            }
+
+            // When pointers differ by one element, first element of returned mask is "1", the rest are "0"
+            byte* ptr = stackalloc byte[Vector<byte>.Count + 1];
+            Vector<byte> mask = Sve2.CreateWhileReadAfterWriteMaskByte(ptr, ptr + 1);
+
+            if (mask.GetElement(0) == 0)
+            {
+                throw new Exception(
+                    $"CreateWhileReadAfterWriteMaskByte(ptr, ptr+1): Expected element 0 to be true, but was false.");
+            }
+
+            for (int i = 1; i < Vector<byte>.Count; i++)
+            {
+                if (mask.GetElement(i) != 0)
+                {
+                    throw new Exception(
+                        $"CreateWhileReadAfterWriteMaskByte(ptr, ptr+1): Expected element {i} to be false, but was true.");
+                }
+            }
+        }
+    }
+}

src/tests/JIT/HardwareIntrinsics/Arm/Sve2/Sve2_r.csproj

@@ -8,6 +8,7 @@
   </PropertyGroup>
   <ItemGroup>
     <Compile Include="Program.Sve2.cs" />
+    <Compile Include="CreateWhileRWMask.cs" />
     <Compile Include="..\Shared\Helpers.cs" />
     <Compile Include="..\Shared\Program.cs" />
     <Compile Include="$(RepoRoot)src/libraries/Common/tests/TestUtilities/System/Buffers/BoundedMemory.cs" />

src/tests/JIT/HardwareIntrinsics/Arm/Sve2/Sve2_ro.csproj

@@ -8,6 +8,7 @@
   </PropertyGroup>
   <ItemGroup>
     <Compile Include="Program.Sve2.cs" />
+    <Compile Include="CreateWhileRWMask.cs" />
     <Compile Include="..\Shared\Helpers.cs" />
     <Compile Include="..\Shared\Program.cs" />
     <Compile Include="$(RepoRoot)src/libraries/Common/tests/TestUtilities/System/Buffers/BoundedMemory.cs" />