Implement IEquatable on the Register struct

ChocolArm64/IntermediateRepresentation/RegisterMask.cs

@@ -43,14 +43,14 @@ namespace ChocolArm64.IntermediateRepresentation
             return obj is RegisterMask regMask && Equals(regMask);
         }
 
-        public override int GetHashCode()
-        {
-            return HashCode.Combine(IntMask, VecMask);
-        }
-
         public bool Equals(RegisterMask other)
         {
             return IntMask == other.IntMask && VecMask == other.VecMask;
         }
+
+        public override int GetHashCode()
+        {
+            return HashCode.Combine(IntMask, VecMask);
+        }
     }
 }

ChocolArm64/State/Register.cs

@@ -3,7 +3,7 @@ using System.Reflection;
 
 namespace ChocolArm64.State
 {
-    struct Register
+    struct Register : IEquatable<Register>
     {
         public int Index;
 
@@ -22,9 +22,12 @@ namespace ChocolArm64.State
 
         public override bool Equals(object obj)
         {
-            return obj is Register reg &&
-                   reg.Index == Index &&
-                   reg.Type  == Type;
+            return obj is Register reg && Equals(reg);
+        }
+
+        public bool Equals(Register other)
+        {
+            return Index == other.Index && Type == other.Type;
         }
 
         public FieldInfo GetField()