Ensure that we don't try and optimize masks for promoted fields

src/coreclr/jit/optimizemaskconversions.cpp

@@ -227,13 +227,22 @@ class MaskConversionsCheckVisitor final : public GenTreeVisitor<MaskConversionsC
                 weight->InvalidateWeight();
                 return fgWalkResult::WALK_CONTINUE;
             }
+
+            // Cannot convert any locals that r promoted struct fields
+            if (varDsc->lvIsStructField)
+            {
+                JITDUMP("is struct field. ");
+                weight->InvalidateWeight();
+                return fgWalkResult::WALK_CONTINUE;
+            }
+
             // TODO: Converting to a mask loses data - as each field is only a single bit.
             // For parameters, OSR locals, and locals which are used as vectors, then they
             // cannot be stored as a mask as data will be lost.
             // For all of these, conversions could be done by creating a new store of type mask.
             // Then uses as mask could be converted to type mask and pointed to use the new
             // definition. The weighting would need updating to take this into account.
-            else if (isLocalUse && !hasConversion)
+            if (isLocalUse && !hasConversion)
             {
                 JITDUMP("is used as vector. ");
                 weight->InvalidateWeight();

src/tests/JIT/Regression/JitBlue/Runtime_110326/Runtime_110326.cs

@@ -0,0 +1,91 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Numerics;
+using System.Runtime.CompilerServices;
+using System.Runtime.Intrinsics;
+using Xunit;
+
+public class Runtime_110326A
+{
+    public struct S1
+    {
+        public bool bool_2;
+        public Vector512<short> v512_short_3;
+        public Vector512<float> v512_float_4;
+    }
+
+    [Fact]
+    public static void TestEntryPoint()
+    {
+        Runtime_110326A.Method1();
+    }
+
+    [MethodImpl(MethodImplOptions.NoInlining)]
+    private static ulong Method1()
+    {
+        S1 s1_s1_d1_f3_160 = new S1();
+        return Vector512.ExtractMostSignificantBits(s1_s1_d1_f3_160.v512_short_3);
+    }
+}
+
+public class Runtime_110326B
+{
+    public struct S2_D1_F2
+    {
+        public struct S2_D2_F2
+        {
+            public Vector<double> v_double_0;
+        }
+
+        public struct S2_D2_F3
+        {
+            public Vector3 v3_10;
+        }
+    }
+
+    public struct S2_D1_F3
+    {
+        public struct S2_D2_F3
+        {
+            public Vector256<int> v256_int_14;
+        }
+
+        public Vector128<long> v128_long_13;
+        public Vector512<uint> v512_uint_16;
+    }
+
+    [Fact]
+    public static void TestEntryPoint()
+    {
+        Runtime_110326B.Method0();
+    }
+
+    [MethodImpl(MethodImplOptions.NoInlining)]
+    private static void Method0()
+    {
+        S2_D1_F2.S2_D2_F2 s2_s2_d1_f2_s2_d2_f2_262 = new S2_D1_F2.S2_D2_F2();
+        S2_D1_F2.S2_D2_F2 s2_s2_d1_f2_s2_d2_f2_263 = s2_s2_d1_f2_s2_d2_f2_262;
+        S2_D1_F2.S2_D2_F3 s2_s2_d1_f2_s2_d2_f3_264 = new S2_D1_F2.S2_D2_F3();
+        S2_D1_F2.S2_D2_F3 s2_s2_d1_f2_s2_d2_f3_265 = s2_s2_d1_f2_s2_d2_f3_264;
+        S2_D1_F2 s2_s2_d1_f2_266 = new S2_D1_F2();
+        S2_D1_F3.S2_D2_F3 s2_s2_d1_f3_s2_d2_f3_268 = new S2_D1_F3.S2_D2_F3();
+        S2_D1_F3 s2_s2_d1_f3_269 = new S2_D1_F3();
+        S2_D1_F3 s2_s2_d1_f3_270 = s2_s2_d1_f3_269;
+        s2_s2_d1_f3_270.v512_uint_16 = Vector512.IsZero(Vector512<uint>.AllBitsSet);
+
+        Log("s2_s2_d1_f", s2_s2_d1_f2_s2_d2_f2_262.v_double_0);
+        Log("s2_s2_d1_f", s2_s2_d1_f2_s2_d2_f2_263.v_double_0);
+        Log("s2_s2_d1_f", s2_s2_d1_f2_s2_d2_f3_264);
+        Log("s2_s2_d1_f", s2_s2_d1_f2_s2_d2_f3_265.v3_10);
+        Log("s2_s2_d1_f", s2_s2_d1_f2_266);
+        Log("s2_s2_d1_f", s2_s2_d1_f3_s2_d2_f3_268.v256_int_14);
+        Log("s2_s2_d1_f", s2_s2_d1_f3_269.v128_long_13);
+        Log("s2_s2_d1_f", s2_s2_d1_f3_270.v128_long_13);
+    }
+
+    [MethodImpl(MethodImplOptions.NoInlining)]
+    private static void Log(string varName, object varValue)
+    {
+    }
+}

src/tests/JIT/Regression/JitBlue/Runtime_110326/Runtime_110326.csproj

@@ -0,0 +1,12 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <Optimize>True</Optimize>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="$(MSBuildProjectName).cs" />
+  </ItemGroup>
+  <ItemGroup>
+    <CLRTestEnvironmentVariable Include="DOTNET_TieredCompilation" Value="0" />
+    <CLRTestEnvironmentVariable Include="DOTNET_JitStress" Value="2" />
+  </ItemGroup>
+</Project>