1 files changed, 19 insertions, 0 deletions
diff --git a/src/mscorlib/src/System/Numerics/Hashing/HashHelpers.cs b/src/mscorlib/src/System/Numerics/Hashing/HashHelpers.cs
new file mode 100644
index 0000000000..0314d1af3c
--- /dev/null
+++ b/src/mscorlib/src/System/Numerics/Hashing/HashHelpers.cs
@@ -0,0 +1,19 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+namespace System.Numerics.Hashing
+{
+    // Please change the corresponding file in corefx if this is changed.
+
+    internal static class HashHelpers
+    {
+        public static int Combine(int h1, int h2)
+        {
+            // The jit optimizes this to use the ROL instruction on x86
+            // Related GitHub pull request: dotnet/coreclr#1830
+            uint shift5 = ((uint)h1 << 5) | ((uint)h1 >> 27);
+            return ((int)shift5 + h1) ^ h2;
+        }
+    }
+}