Ensure that negation of floating-point values is correctly handled

Author: tannergooding

src/coreclr/jit/simd.h

@@ -368,6 +368,11 @@ TBase EvaluateUnaryScalarSpecialized(genTreeOps oper, TBase arg0)
 {
     switch (oper)
     {
+        case GT_NEG:
+        {
+            return static_cast<TBase>(0) - arg0;
+        }
+
         case GT_NOT:
         {
             return ~arg0;
@@ -399,6 +404,11 @@ TBase EvaluateUnaryScalarSpecialized(genTreeOps oper, TBase arg0)
 template <>
 inline float EvaluateUnaryScalarSpecialized<float>(genTreeOps oper, float arg0)
 {
+    if (oper == GT_NEG)
+    {
+        return -arg0;
+    }
+
     uint32_t arg0Bits   = BitOperations::SingleToUInt32Bits(arg0);
     uint32_t resultBits = EvaluateUnaryScalarSpecialized<uint32_t>(oper, arg0Bits);
     return BitOperations::UInt32BitsToSingle(resultBits);
@@ -407,6 +417,11 @@ inline float EvaluateUnaryScalarSpecialized<float>(genTreeOps oper, float arg0)
 template <>
 inline double EvaluateUnaryScalarSpecialized<double>(genTreeOps oper, double arg0)
 {
+    if (oper == GT_NEG)
+    {
+        return -arg0;
+    }
+
     uint64_t arg0Bits   = BitOperations::DoubleToUInt64Bits(arg0);
     uint64_t resultBits = EvaluateUnaryScalarSpecialized<uint64_t>(oper, arg0Bits);
     return BitOperations::UInt64BitsToDouble(resultBits);
@@ -415,18 +430,7 @@ inline double EvaluateUnaryScalarSpecialized<double>(genTreeOps oper, double arg
 template <typename TBase>
 TBase EvaluateUnaryScalar(genTreeOps oper, TBase arg0)
 {
-    switch (oper)
-    {
-        case GT_NEG:
-        {
-            return static_cast<TBase>(0) - arg0;
-        }
-
-        default:
-        {
-            return EvaluateUnaryScalarSpecialized<TBase>(oper, arg0);
-        }
-    }
+    return EvaluateUnaryScalarSpecialized<TBase>(oper, arg0);
 }
 
 #if defined(FEATURE_MASKED_HW_INTRINSICS)

src/tests/JIT/Regression/JitBlue/Runtime_105627/Runtime_105627.cs

@@ -0,0 +1,36 @@
+// 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.Runtime.CompilerServices;
+using System.Numerics;
+using System.Runtime.Intrinsics;
+using System.Runtime.Intrinsics.Arm;
+using Xunit;
+
+// 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]
+
+public class Runtime_105627
+{
+    public static Vector128<double> s_9;
+
+    [Fact]
+    public static void TestEntyPoint()
+    {
+        var vr1 = Vector128.CreateScalar(0d);
+
+        if (AdvSimd.IsSupported)
+        {
+            s_9 = AdvSimd.Arm64.Negate(vr1);
+        }
+        else
+        {
+            s_9 = -vr1;
+        }
+        Assert.Equal(Vector128.Create<ulong>(0x80000000_00000000UL, s_9.AsUInt64()));
+    }
+}

src/tests/JIT/Regression/JitBlue/Runtime_105627/Runtime_105627.csproj

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