Faster FastAbs

src/ImageSharp/Common/Helpers/ImageMaths.cs

@@ -25,7 +25,8 @@ namespace ImageSharp
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public static int FastAbs(int x)
         {
-            return (x ^ (x >> 31)) - (x >> 31);
+            int y = x >> 31;
+            return (x ^ y) - y;
         }
 
         /// <summary>

tests/ImageSharp.Benchmarks/General/Abs.cs

@@ -29,5 +29,13 @@
             int x = this.X;
             return (x ^ (x >> 31)) - (x >> 31);
         }
+
+        [Benchmark(Description = "Bitwise Abs With Variable")]
+        public int AbsBitwiseVer()
+        {
+            int x = this.X;
+            int y = x >> 31;
+            return (x ^ y) - y;
+        }
     }
 }