JIT: Fix containment check for decomposed long halves in CreateScalar (#114654)

* fix containment check for decomposed long halves in CreateScalar

* add IsSupported check to test

Author: saucecontrol

src/coreclr/jit/lowerxarch.cpp

@@ -9893,7 +9893,8 @@ void Lowering::ContainCheckHWIntrinsic(GenTreeHWIntrinsic* node)
 
                             for (GenTree* longOp : op1->Operands())
                             {
-                                if (IsContainableMemoryOp(longOp) && IsSafeToContainMem(node, longOp))
+                                if (!varTypeIsSmall(longOp) && IsContainableMemoryOp(longOp) &&
+                                    IsSafeToContainMem(node, longOp))
                                 {
                                     MakeSrcContained(node, longOp);
                                 }

src/tests/JIT/Regression/JitBlue/Runtime_114570/Runtime_114570.cs

@@ -0,0 +1,53 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+// Generated by Fuzzlyn v2.5 on 2025-04-11 19:36:22
+// Run on X86 Windows
+// Seed: 2880609996874211534-vectort,vector128,vector256,x86aes,x86avx,x86avx2,x86avx512bw,x86avx512bwvl,x86avx512cd,x86avx512cdvl,x86avx512dq,x86avx512dqvl,x86avx512f,x86avx512fvl,x86bmi1,x86bmi2,x86fma,x86lzcnt,x86pclmulqdq,x86popcnt,x86sse,x86sse2,x86sse3,x86sse41,x86sse42,x86ssse3,x86x86base
+// Reduced from 130.6 KiB to 0.9 KiB in 00:04:12
+// Hits JIT assert in Release:
+// Assertion failed 'isContainable || supportsRegOptional' in 'Program:M8():System.Runtime.Intrinsics.Vector128`1[ulong]' during 'Generate code' (IL size 39; hash 0x72979674; FullOpts)
+using System;
+using System.Runtime.Intrinsics;
+using System.Runtime.Intrinsics.X86;
+using Xunit;
+
+public class Runtime_114570
+{
+    public static IRuntime s_rt = new Runtime();
+    public static byte s_1;
+    public static Vector128<sbyte> s_17;
+    public static uint s_22;
+
+    [Fact]
+    public static void Problem()
+    {
+        if (Bmi1.IsSupported)
+        {
+            var vr17 = M8();
+        }
+    }
+
+    public static Vector128<ulong> M8()
+    {
+        var vr6 = Vector128.Create(0, 0, s_22, 0);
+        var vr3 = (ulong)Bmi1.AndNot(0, M23(vr6, ref s_17));
+        return Vector128.CreateScalar(vr3);
+    }
+
+    public static ref byte M23(Vector128<uint> arg0, ref Vector128<sbyte> arg1)
+    {
+        s_rt.WriteLine(arg0);
+        return ref s_1;
+    }
+}
+
+public interface IRuntime
+{
+    void WriteLine<T>(T value);
+}
+
+public class Runtime : IRuntime
+{
+    public void WriteLine<T>(T value) => Console.WriteLine(value);
+}

src/tests/JIT/Regression/JitBlue/Runtime_114570/Runtime_114570.csproj

@@ -0,0 +1,8 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <Optimize>True</Optimize>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="$(MSBuildProjectName).cs" />
+  </ItemGroup>
+</Project>