From 132be64c3c4781106b8da4328d39dcd0c696921d Mon Sep 17 00:00:00 2001
From: Kunal Pathak <Kunal.Pathak@microsoft.com>
Date: Mon, 15 Jun 2020 23:40:16 -0700
Subject: [PATCH] Replace Create(ulong) with CreateScalar(uint) in PopCount
 (#37912)

* Replace Create(ulong) with CreateScalar(uint)
* Add CreateScalar() in shim
---
 .../System.Private.CoreLib/src/System/Numerics/BitOperations.cs     | 6 +-----
 .../src/System/Runtime/Intrinsics/Intrinsics.Shims.cs               | 1 +
 2 files changed, 2 insertions(+), 5 deletions(-)

diff --git a/src/libraries/System.Private.CoreLib/src/System/Numerics/BitOperations.cs b/src/libraries/System.Private.CoreLib/src/System/Numerics/BitOperations.cs
index 28b3416..a222296 100644
--- a/src/libraries/System.Private.CoreLib/src/System/Numerics/BitOperations.cs
+++ b/src/libraries/System.Private.CoreLib/src/System/Numerics/BitOperations.cs
@@ -241,11 +241,7 @@ namespace System.Numerics
             {
                 // PopCount works on vector so convert input value to vector first.
 
-                // Vector64.CreateScalar(uint) generates suboptimal code by storing and
-                // loading the result to memory.
-                // See https://github.com/dotnet/runtime/issues/35976 for details.
-                // Hence use Vector64.Create(ulong) to create Vector64<ulong> and operate on that.
-                Vector64<ulong> input = Vector64.Create((ulong)value);
+                Vector64<uint> input = Vector64.CreateScalar(value);
                 Vector64<byte> aggregated = AdvSimd.Arm64.AddAcross(AdvSimd.PopCount(input.AsByte()));
                 return aggregated.ToScalar();
             }
diff --git a/src/libraries/System.Utf8String.Experimental/src/System/Runtime/Intrinsics/Intrinsics.Shims.cs b/src/libraries/System.Utf8String.Experimental/src/System/Runtime/Intrinsics/Intrinsics.Shims.cs
index 38e129a..9d08032 100644
--- a/src/libraries/System.Utf8String.Experimental/src/System/Runtime/Intrinsics/Intrinsics.Shims.cs
+++ b/src/libraries/System.Utf8String.Experimental/src/System/Runtime/Intrinsics/Intrinsics.Shims.cs
@@ -7,6 +7,7 @@ namespace System.Runtime.Intrinsics
     internal static class Vector64
     {
         public static Vector64<ulong> Create(ulong value) => throw new PlatformNotSupportedException();
+        public static Vector64<uint> CreateScalar(uint value) => throw new PlatformNotSupportedException();
         public static Vector64<byte> AsByte<T>(this Vector64<T> vector) where T : struct => throw new PlatformNotSupportedException();
     }
     internal readonly struct Vector64<T>
-- 
2.7.4