Workaround an MSVC bug with __libm_sse2_sincos_

src/coreclr/classlibnative/float/floatdouble.cpp

@@ -253,6 +253,12 @@ FCIMPL1_V(double, COMDouble::Sin, double x)
     return sin(x);
 FCIMPLEND
 
+#if defined(_MSC_VER) && defined(TARGET_AMD64)
+// The /fp:fast form of `sincos` for AMD64 returns sin twice, rather than sincos
+#pragma float_control(push)
+#pragma float_control(precise, on)
+#endif
+
 /*====================================SinCos====================================
 **
 ==============================================================================*/
@@ -268,6 +274,10 @@ FCIMPL3_VII(void, COMDouble::SinCos, double x, double* pSin, double* pCos)
 
 FCIMPLEND
 
+#if defined(_MSC_VER) && defined(TARGET_AMD64)
+#pragma float_control(pop)
+#endif
+
 /*=====================================Sinh=====================================
 **
 ==============================================================================*/

src/coreclr/classlibnative/float/floatsingle.cpp

@@ -228,6 +228,12 @@ FCIMPL1_V(float, COMSingle::Sin, float x)
     return sinf(x);
 FCIMPLEND
 
+#if defined(_MSC_VER) && defined(TARGET_AMD64)
+// The /fp:fast form of `sincos` for AMD64 returns sin twice, rather than sincos
+#pragma float_control(push)
+#pragma float_control(precise, on)
+#endif
+
 /*====================================SinCos====================================
 **
 ==============================================================================*/
@@ -243,6 +249,10 @@ FCIMPL3_VII(void, COMSingle::SinCos, float x, float* pSin, float* pCos)
 
 FCIMPLEND
 
+#if defined(_MSC_VER) && defined(TARGET_AMD64)
+#pragma float_control(pop)
+#endif
+
 /*=====================================Sinh=====================================
 **
 ==============================================================================*/

src/tests/JIT/Regression/JitBlue/Runtime_98204/Runtime_98204.cs

@@ -0,0 +1,35 @@
+// 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 Xunit;
+
+public static class Runtime_98068
+{
+    [Fact]
+    [InlineData(1e18)]
+    public static void TestSinCosDouble(double d)
+    {
+        double sin1 = Math.Sin(d);
+        double cos1 = Math.Cos(d);
+
+        (double sin2, double cos2) = Math.SinCos(d);
+
+        Assert.Equal(sin1, sin2);
+        Assert.Equal(cos1, cos2);
+    }
+
+    [Fact]
+    [InlineData(1e18f)]
+    public static void TestSinCosSingle(float f)
+    {
+        float sin1 = MathF.Sin(f);
+        float cos1 = MathF.Cos(f);
+
+        (float sin2, float cos2) = MathF.SinCos(f);
+
+        Assert.Equal(sin1, sin2);
+        Assert.Equal(cos1, cos2);
+    }
+}

src/tests/JIT/Regression/JitBlue/Runtime_98204/Runtime_98204.csproj

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