Use EqualityComparer<TKey>.Default.Equals intrinsic

Author: benaadams

src/mscorlib/src/System/Collections/Generic/Dictionary.cs

@@ -400,8 +400,7 @@ private ref Entry FindEntry<TComparer>(TKey key, out bool found, IEqualityCompar
                     {
                         if (typeof(TComparer) == typeof(DefaultComparer))
                         {
-                            // Change to EqualityComparer<T>.Default when Jit recognises intrinsic https://github.com/dotnet/coreclr/pull/14125
-                            if (default(TKey) == null ? entry.key.Equals(key) : StructKeyEquals(entry.key, key))
+                            if (EqualityComparer<TKey>.Default.Equals(entry.key, key))
                             {
                                 return ref entry;
                             }
@@ -502,8 +501,7 @@ private bool TryInsert<TInsertionBehavior, TComparer>(TKey key, TValue value, IE
                     bool keysEqual = false;
                     if (typeof(TComparer) == typeof(DefaultComparer))
                     {
-                        // Change to EqualityComparer<T>.Default when Jit recognises intrinsic https://github.com/dotnet/coreclr/pull/14125
-                        keysEqual = default(TKey) == null ? candidateEntry.key.Equals(key) : StructKeyEquals(candidateEntry.key, key);
+                        keysEqual = EqualityComparer<TKey>.Default.Equals(candidateEntry.key, key);
                     }
                     else if (typeof(TComparer) == typeof(CustomComparer))
                     {
@@ -784,8 +782,7 @@ private ref Entry Remove<TComparer>(TKey key, out bool success, IEqualityCompare
                         bool keysEqual = false;
                         if (typeof(TComparer) == typeof(DefaultComparer))
                         {
-                            // Change to EqualityComparer<T>.Default when Jit recognises intrinsic https://github.com/dotnet/coreclr/pull/14125
-                            keysEqual = default(TKey) == null ? entry.key.Equals(key) : StructKeyEquals(entry.key, key);
+                            keysEqual = EqualityComparer<TKey>.Default.Equals(entry.key, key);
                         }
                         else if (typeof(TComparer) == typeof(CustomComparer))
                         {
@@ -838,69 +835,6 @@ public bool TryGetValue(TKey key, out TValue value)
 
         public bool TryAdd(TKey key, TValue value) => TryInsert<RejectIfExisting>(key, value);
 
-        // Replace with EqualityComparer<T>.Default when Jit recognises intrinsic https://github.com/dotnet/coreclr/pull/14125
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private bool StructKeyEquals(TKey key0, TKey key1)
-        {
-            Debug.Assert(default(TKey) != null);
-
-            // Specialize equality for each of the BCL ValueType primitives
-            // cast via object to the type and use them directly
-            // the Jit will elide the boxing.
-            if (typeof(TKey) == typeof(byte))
-            {
-                return (byte)(object)key0 == (byte)(object)key1;
-            }
-            else if (typeof(TKey) == typeof(sbyte))
-            {
-                return (sbyte)(object)key0 == (sbyte)(object)key1;
-            }
-            else if (typeof(TKey) == typeof(ushort))
-            {
-                return (ushort)(object)key0 == (ushort)(object)key1;
-            }
-            else if (typeof(TKey) == typeof(short))
-            {
-                return (short)(object)key0 == (short)(object)key1;
-            }
-            else if (typeof(TKey) == typeof(char))
-            {
-                return (char)(object)key0 == (char)(object)key1;
-            }
-            else if (typeof(TKey) == typeof(uint))
-            {
-                return (uint)(object)key0 == (uint)(object)key1;
-            }
-            else if (typeof(TKey) == typeof(int))
-            {
-                return (int)(object)key0 == (int)(object)key1;
-            }
-            else if (typeof(TKey) == typeof(ulong))
-            {
-                return (ulong)(object)key0 == (ulong)(object)key1;
-            }
-            else if (typeof(TKey) == typeof(long))
-            {
-                return (long)(object)key0 == (long)(object)key1;
-            }
-            else if (typeof(TKey) == typeof(IntPtr))
-            {
-                return (IntPtr)(object)key0 == (IntPtr)(object)key1;
-            }
-            else if (typeof(TKey) == typeof(UIntPtr))
-            {
-                return (UIntPtr)(object)key0 == (UIntPtr)(object)key1;
-            }
-            else if (typeof(TKey) == typeof(Guid))
-            {
-                return (Guid)(object)key0 == (Guid)(object)key1;
-            }
-            else
-            {
-                return EqualityComparer<TKey>.Default.Equals(key0, key1);
-            }
-        }
-
         bool ICollection<KeyValuePair<TKey, TValue>>.IsReadOnly => false;
 
         void ICollection<KeyValuePair<TKey, TValue>>.CopyTo(KeyValuePair<TKey, TValue>[] array, int index) => CopyTo(array, index);