Simplify some more CompareTo methods

Author: lilinus

src/libraries/System.Private.CoreLib/src/System/Byte.cs

@@ -58,12 +58,12 @@ public int CompareTo(object? value)
             {
                 return 1;
             }
-            if (!(value is byte))
+            if (value is not byte other)
             {
                 throw new ArgumentException(SR.Arg_MustBeByte);
             }
 
-            return m_value - (((byte)value).m_value);
+            return CompareTo(other);
         }
 
         public int CompareTo(byte value)

src/libraries/System.Private.CoreLib/src/System/Char.cs

@@ -140,12 +140,12 @@ public int CompareTo(object? value)
             {
                 return 1;
             }
-            if (!(value is char))
+            if (value is not char other)
             {
                 throw new ArgumentException(SR.Arg_MustBeChar);
             }
 
-            return m_value - ((char)value).m_value;
+            return CompareTo(other);
         }
 
         public int CompareTo(char value)

src/libraries/System.Private.CoreLib/src/System/Decimal.cs

@@ -420,11 +420,10 @@ public int CompareTo(object? value)
         {
             if (value == null)
                 return 1;
-            if (!(value is decimal))
+            if (value is not decimal other)
                 throw new ArgumentException(SR.Arg_MustBeDecimal);
 
-            decimal other = (decimal)value;
-            return DecCalc.VarDecCmp(in this, in other);
+            return CompareTo(other);
         }
 
         public int CompareTo(decimal value)

src/libraries/System.Private.CoreLib/src/System/Int16.cs

@@ -60,9 +60,9 @@ public int CompareTo(object? value)
                 return 1;
             }
 
-            if (value is short)
+            if (value is short other)
             {
-                return m_value - ((short)value).m_value;
+                return CompareTo(other);
             }
 
             throw new ArgumentException(SR.Arg_MustBeInt16);

src/libraries/System.Private.CoreLib/src/System/Int32.cs

@@ -63,13 +63,9 @@ public int CompareTo(object? value)
                 return 1;
             }
 
-            // NOTE: Cannot use return (_value - value) as this causes a wrap
-            // around in cases where _value - value > MaxValue.
             if (value is int i)
             {
-                if (m_value < i) return -1;
-                if (m_value > i) return 1;
-                return 0;
+                return CompareTo(i);
             }
 
             throw new ArgumentException(SR.Arg_MustBeInt32);

src/libraries/System.Private.CoreLib/src/System/Int64.cs

@@ -60,13 +60,9 @@ public int CompareTo(object? value)
                 return 1;
             }
 
-            // Need to use compare because subtraction will wrap
-            // to positive for very large neg numbers, etc.
             if (value is long i)
             {
-                if (m_value < i) return -1;
-                if (m_value > i) return 1;
-                return 0;
+                return CompareTo(i);
             }
 
             throw new ArgumentException(SR.Arg_MustBeInt64);

src/libraries/System.Private.CoreLib/src/System/SByte.cs

@@ -62,11 +62,11 @@ public int CompareTo(object? obj)
             {
                 return 1;
             }
-            if (!(obj is sbyte))
+            if (obj is not sbyte other)
             {
                 throw new ArgumentException(SR.Arg_MustBeSByte);
             }
-            return m_value - ((sbyte)obj).m_value;
+            return CompareTo(other);
         }
 
         public int CompareTo(sbyte value)

src/libraries/System.Private.CoreLib/src/System/UInt16.cs

@@ -56,9 +56,9 @@ public int CompareTo(object? value)
             {
                 return 1;
             }
-            if (value is ushort)
+            if (value is ushort other)
             {
-                return (int)m_value - (int)(((ushort)value).m_value);
+                return CompareTo(other);
             }
             throw new ArgumentException(SR.Arg_MustBeUInt16);
         }

src/libraries/System.Private.CoreLib/src/System/UInt32.cs

@@ -57,13 +57,9 @@ public int CompareTo(object? value)
                 return 1;
             }
 
-            // Need to use compare because subtraction will wrap
-            // to positive for very large neg numbers, etc.
             if (value is uint i)
             {
-                if (m_value < i) return -1;
-                if (m_value > i) return 1;
-                return 0;
+                return CompareTo(i);
             }
 
             throw new ArgumentException(SR.Arg_MustBeUInt32);

src/libraries/System.Private.CoreLib/src/System/UInt64.cs

@@ -57,13 +57,9 @@ public int CompareTo(object? value)
                 return 1;
             }
 
-            // Need to use compare because subtraction will wrap
-            // to positive for very large neg numbers, etc.
             if (value is ulong i)
             {
-                if (m_value < i) return -1;
-                if (m_value > i) return 1;
-                return 0;
+                return CompareTo(i);
             }
 
             throw new ArgumentException(SR.Arg_MustBeUInt64);