Remove the "anything + null => null" optimization

src/coreclr/jit/morph.cpp

@@ -12332,27 +12332,9 @@ GenTree* Compiler::fgMorphSmpOp(GenTree* tree, MorphAddrContext* mac)
 
                 if (op2->IsCnsIntOrI() && varTypeIsIntegralOrI(typ))
                 {
-                    CLANG_FORMAT_COMMENT_ANCHOR;
-
                     // Fold (x + 0).
-
                     if ((op2->AsIntConCommon()->IconValue() == 0) && !gtIsActiveCSE_Candidate(tree))
                     {
-
-                        // If this addition is adding an offset to a null pointer,
-                        // avoid the work and yield the null pointer immediately.
-                        // Dereferencing the pointer in either case will have the
-                        // same effect.
-
-                        if (!optValnumCSE_phase && varTypeIsGC(op2->TypeGet()) &&
-                            ((op1->gtFlags & GTF_ALL_EFFECT) == 0))
-                        {
-                            op2->gtType = tree->gtType;
-                            DEBUG_DESTROY_NODE(op1);
-                            DEBUG_DESTROY_NODE(tree);
-                            return op2;
-                        }
-
                         // Remove the addition iff it won't change the tree type
                         // to TYP_REF.
 

src/tests/JIT/Regression/JitBlue/Runtime_61510/Runtime_61510.cs

@@ -0,0 +1,23 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Runtime.CompilerServices;
+
+unsafe class Runtime_61510
+{
+    [FixedAddressValueType]
+    private static byte s_field;
+
+    public static int Main()
+    {
+        ref byte result = ref AddZeroByrefToNativeInt((nint)Unsafe.AsPointer(ref s_field));
+
+        return Unsafe.AreSame(ref s_field, ref result) ? 100 : 101;
+    }
+
+    [MethodImpl(MethodImplOptions.NoInlining)]
+    private static ref byte AddZeroByrefToNativeInt(nint addr)
+    {
+        return ref Unsafe.Add(ref Unsafe.NullRef<byte>(), addr);
+    }
+}

src/tests/JIT/Regression/JitBlue/Runtime_61510/Runtime_61510.csproj

@@ -0,0 +1,10 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <Optimize>True</Optimize>
+    <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="$(MSBuildProjectName).cs" />
+  </ItemGroup>
+</Project>