Fix constant folding for shift SIMD operators (dotnet#105752)

src/coreclr/jit/gentree.cpp

@@ -30912,10 +30912,7 @@ GenTree* Compiler::gtFoldExprHWIntrinsic(GenTreeHWIntrinsic* tree)
                 {
                     if (otherNode->TypeIs(TYP_SIMD16))
                     {
-                        if ((ni != NI_AVX2_ShiftLeftLogicalVariable) && (ni != NI_AVX2_ShiftRightArithmeticVariable) &&
-                            (ni != NI_AVX512F_VL_ShiftRightArithmeticVariable) &&
-                            (ni != NI_AVX10v1_ShiftRightArithmeticVariable) &&
-                            (ni != NI_AVX2_ShiftRightLogicalVariable))
+                        if (!HWIntrinsicInfo::IsVariableShift(ni))
                         {
                             // The xarch shift instructions support taking the shift amount as
                             // a simd16, in which case they take the shift amount from the lower

src/coreclr/jit/hwintrinsic.h

@@ -882,6 +882,32 @@ struct HWIntrinsicInfo
         }
     }
 
+    static bool IsVariableShift(NamedIntrinsic id)
+    {
+#ifdef TARGET_XARCH
+        switch (id)
+        {
+            case NI_AVX2_ShiftRightArithmeticVariable:
+            case NI_AVX512F_ShiftRightArithmeticVariable:
+            case NI_AVX512F_VL_ShiftRightArithmeticVariable:
+            case NI_AVX512BW_ShiftRightArithmeticVariable:
+            case NI_AVX512BW_VL_ShiftRightArithmeticVariable:
+            case NI_AVX10v1_ShiftRightArithmeticVariable:
+            case NI_AVX2_ShiftRightLogicalVariable:
+            case NI_AVX512F_ShiftRightLogicalVariable:
+            case NI_AVX512BW_ShiftRightLogicalVariable:
+            case NI_AVX512BW_VL_ShiftRightLogicalVariable:
+            case NI_AVX10v1_ShiftRightLogicalVariable:
+            case NI_AVX2_ShiftLeftLogicalVariable:
+            case NI_AVX512BW_VL_ShiftLeftLogicalVariable:
+                return true;
+            default:
+                return false;
+        }
+#endif // TARGET_XARCH
+        return false;
+    }
+
     static bool HasImmediateOperand(NamedIntrinsic id)
     {
 #if defined(TARGET_ARM64)

src/coreclr/jit/valuenum.cpp

@@ -8235,9 +8235,7 @@ ValueNum ValueNumStore::EvalHWIntrinsicFunBinary(GenTreeHWIntrinsic* tree,
             {
                 if (TypeOfVN(arg1VN) == TYP_SIMD16)
                 {
-                    if ((ni != NI_AVX2_ShiftLeftLogicalVariable) && (ni != NI_AVX2_ShiftRightArithmeticVariable) &&
-                        (ni != NI_AVX512F_VL_ShiftRightArithmeticVariable) &&
-                        (ni != NI_AVX10v1_ShiftRightArithmeticVariable) && (ni != NI_AVX2_ShiftRightLogicalVariable))
+                    if (!HWIntrinsicInfo::IsVariableShift(ni))
                     {
                         // The xarch shift instructions support taking the shift amount as
                         // a simd16, in which case they take the shift amount from the lower

src/tests/JIT/Regression/JitBlue/Runtime_105742/Runtime_105742.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.
+
+// Run on Arm64 Linux
+// Seed: 10489942769529190437-vectort,vector64,vector128,armadvsimd,armadvsimdarm64,armaes,armarmbase,armarmbasearm64,armcrc32,armcrc32arm64,armdp,armrdm,armrdmarm64,armsha1,armsha256
+// Reduced from 58.9 KiB to 0.4 KiB in 00:00:28
+// Debug: Outputs [9223372036854775808, 9223372036854775808]
+// Release: Outputs [0, 0]
+
+using System;
+using System.Runtime.CompilerServices;
+using System.Runtime.Intrinsics;
+using System.Runtime.Intrinsics.X86;
+using Xunit;
+
+public class Runtime_105742
+{
+    [Fact]
+    public static void TestEntyPoint()
+    {
+        if (!Avx512BW.VL.IsSupported)
+        {
+            return;
+        }
+
+        if (ShiftLeft().ToString() != "<2, 1, 1, 1, 1, 1, 1, 1>")
+        {
+            throw new Exception("ShiftLeft");
+        }
+        if (ShiftRight().ToString() != "<0, 32767, -1, -1, -1, -1, -1, -1>")
+        {
+            throw new Exception("ShiftRight");
+        }
+    }
+
+    [MethodImpl(MethodImplOptions.NoInlining)]
+    private static Vector128<short> ShiftLeft()
+    {
+        var vr4 = Vector128.Create<short>(1);
+        var vr5 = (ushort)1;
+        var vr6 = Vector128.CreateScalar(vr5);
+        var vr7 = Avx512BW.VL.ShiftLeftLogicalVariable(vr4, vr6);
+        return vr7;
+    }
+
+    [MethodImpl(MethodImplOptions.NoInlining)]
+    private static Vector128<short> ShiftRight()
+    {
+        var vr2 = Vector128.Create<short>(-1);
+        var vr3 = Vector128.Create(65534, 1, 0, 0, 0, 0, 0, 0);
+        return Avx512BW.VL.ShiftRightLogicalVariable(vr2, vr3);
+    }
+}

src/tests/JIT/Regression/JitBlue/Runtime_105742/Runtime_105742.csproj

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