Fixing Span IndexOf vectorization.

dotnet · Mar 24, 2017 · 22e4c23 · 22e4c23
1 parent d1c4eea
commit 22e4c23
Showing 1 changed file with 5 additions and 4 deletions.
diff --git a/src/System.Memory/src/System/SpanHelpers.byte.cs b/src/System.Memory/src/System/SpanHelpers.byte.cs
@@ -61,7 +61,7 @@ public static unsafe int IndexOf(ref byte searchSpace, byte value, int length)
                 unchecked
                 {
                     int unaligned = (int)(byte*)Unsafe.AsPointer(ref searchSpace) & (Vector<byte>.Count - 1);
-                    nLength = (IntPtr)(uint)unaligned;
+                    nLength = (IntPtr)(uint)((Vector<byte>.Count - unaligned) % Vector<byte>.Count);
                 }
             }
         SequentialScan:
@@ -122,15 +122,16 @@ public static unsafe int IndexOf(ref byte searchSpace, byte value, int length)
                 {
                     goto NotFound;
                 }
-                nLength = (IntPtr)(uint)(length - Vector<byte>.Count);
+                nLength = (IntPtr)(uint)(length - (uint)index);
                 // Get comparision Vector
                 Vector<byte> vComparision = GetVector(value);
-                while ((byte*)nLength > (byte*)index)
+                while ((byte*)nLength >= (byte*)Vector<byte>.Count)
                 {
                     var vMatches = Vector.Equals(vComparision, Unsafe.ReadUnaligned<Vector<byte>>(ref Unsafe.AddByteOffset(ref searchSpace, index)));
                     if (Vector<byte>.Zero.Equals(vMatches))
                     {
                         index += Vector<byte>.Count;
+                        nLength -= Vector<byte>.Count;
                         continue;
                     }
                     // Found match, reuse Vector vComparision to keep register pressure low
@@ -139,7 +140,7 @@ public static unsafe int IndexOf(ref byte searchSpace, byte value, int length)
                     goto VectorFound;
                 }
 
-                if ((int)(byte*)index > length)
+                if ((int)(byte*)index >= length)
                 {
                     goto NotFound;
                 }