Vectorize Convert.ToBase64String

src/libraries/System.Memory/src/System/Buffers/Text/Base64.cs → src/libraries/Common/src/System/Buffers/Text/Base64.cs

@@ -6,7 +6,12 @@
 
 namespace System.Buffers.Text
 {
-    public static partial class Base64
+#if SYSTEM_PRIVATE_CORELIB
+    public
+#else
+    internal
+#endif
+        static partial class Base64
     {
         [Conditional("DEBUG")]
         private static unsafe void AssertRead<TVector>(byte* src, byte* srcStart, int srcLength)

src/libraries/System.Memory/src/System/Buffers/Text/Base64Decoder.cs → src/libraries/Common/src/System/Buffers/Text/Base64Decoder.cs

@@ -13,7 +13,12 @@ namespace System.Buffers.Text
     // AVX2 version based on https://github.com/aklomp/base64/tree/e516d769a2a432c08404f1981e73b431566057be/lib/arch/avx2
     // Vector128 version based on https://github.com/aklomp/base64/tree/e516d769a2a432c08404f1981e73b431566057be/lib/arch/ssse3
 
-    public static partial class Base64
+#if SYSTEM_PRIVATE_CORELIB
+    public
+#else
+    internal
+#endif
+        static partial class Base64
     {
         /// <summary>
         /// Decode the span of UTF-8 encoded text represented as base64 into binary data.
@@ -477,22 +482,6 @@ private static unsafe void Avx2Decode(ref byte* srcBytes, ref byte* destBytes, b
             destBytes = dest;
         }
 
-        // This can be replaced once https://github.com/dotnet/runtime/issues/63331 is implemented.
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private static Vector128<byte> SimdShuffle(Vector128<byte> left, Vector128<byte> right, Vector128<byte> mask8F)
-        {
-            Debug.Assert((Ssse3.IsSupported || AdvSimd.Arm64.IsSupported) && BitConverter.IsLittleEndian);
-
-            if (Ssse3.IsSupported)
-            {
-                return Ssse3.Shuffle(left, right);
-            }
-            else
-            {
-                return AdvSimd.Arm64.VectorTableLookup(left, Vector128.BitwiseAnd(right, mask8F));
-            }
-        }
-
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         private static unsafe void Vector128Decode(ref byte* srcBytes, ref byte* destBytes, byte* srcEnd, int sourceLength, int destLength, byte* srcStart, byte* destStart)
         {

src/libraries/System.Memory/src/System/Buffers/Text/Base64Encoder.cs → src/libraries/Common/src/System/Buffers/Text/Base64Encoder.cs

@@ -1,6 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.Diagnostics;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 using System.Runtime.Intrinsics;
@@ -15,8 +16,29 @@ namespace System.Buffers.Text
     /// <summary>
     /// Convert between binary data and UTF-8 encoded text that is represented in base 64.
     /// </summary>
-    public static partial class Base64
+#if SYSTEM_PRIVATE_CORELIB
+    public
+#else
+    internal
+#endif
+        static partial class Base64
     {
+        // This can be replaced once https://github.com/dotnet/runtime/issues/63331 is implemented.
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static Vector128<byte> SimdShuffle(Vector128<byte> left, Vector128<byte> right, Vector128<byte> mask8F)
+        {
+            Debug.Assert((Ssse3.IsSupported || AdvSimd.Arm64.IsSupported) && BitConverter.IsLittleEndian);
+
+            if (Ssse3.IsSupported)
+            {
+                return Ssse3.Shuffle(left, right);
+            }
+            else
+            {
+                return AdvSimd.Arm64.VectorTableLookup(left, Vector128.BitwiseAnd(right, mask8F));
+            }
+        }
+
         /// <summary>
         /// Encode the span of binary data into UTF-8 encoded text represented as base64.
         /// </summary>

src/libraries/System.Memory/src/System.Memory.csproj

@@ -25,9 +25,9 @@
     <Compile Include="System\Buffers\SequenceReader.cs" />
     <Compile Include="System\Buffers\SequenceReader.Search.cs" />
     <Compile Include="System\Buffers\SequenceReaderExtensions.Binary.cs" />
-    <Compile Include="System\Buffers\Text\Base64.cs" />
-    <Compile Include="System\Buffers\Text\Base64Decoder.cs" />
-    <Compile Include="System\Buffers\Text\Base64Encoder.cs" />
+    <Compile Include="$(CommonPath)System\Buffers\Text\Base64.cs" />
+    <Compile Include="$(CommonPath)System\Buffers\Text\Base64Decoder.cs" />
+    <Compile Include="$(CommonPath)System\Buffers\Text\Base64Encoder.cs" />
     <Compile Include="System\Runtime\InteropServices\SequenceMarshal.cs" />
     <Compile Include="System\Text\EncodingExtensions.cs" />
   </ItemGroup>

src/libraries/System.Private.CoreLib/src/System.Private.CoreLib.Shared.projitems

@@ -243,6 +243,8 @@
     <Compile Include="$(MSBuildThisFileDirectory)System\Configuration\Assemblies\AssemblyVersionCompatibility.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Context.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Convert.Base64.cs" />
+    <Compile Include="$(CommonPath)System\Buffers\Text\Base64.cs" />
+    <Compile Include="$(CommonPath)System\Buffers\Text\Base64Encoder.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Convert.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\CoreLib.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\CurrentSystemTimeZone.cs" />

src/libraries/System.Private.CoreLib/src/System/Convert.cs

@@ -6,6 +6,9 @@
 using System.Globalization;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
+using System.Buffers;
+using System.Buffers.Text;
+using System.Text;
 
 namespace System
 {
@@ -2336,7 +2339,24 @@ public static string ToBase64String(ReadOnlySpan<byte> bytes, Base64FormattingOp
             }
 
             bool insertLineBreaks = (options == Base64FormattingOptions.InsertLineBreaks);
-            string result = string.FastAllocateString(ToBase64_CalculateAndValidateOutputLength(bytes.Length, insertLineBreaks));
+            int outputLength = ToBase64_CalculateAndValidateOutputLength(bytes.Length, insertLineBreaks);
+
+            if (!insertLineBreaks && bytes.Length >= 64)
+            {
+                // For large inputs it's faster to allocate a temp buffer and call UTF8 version
+                // which is then extended to UTF8 via Latin1.GetString (base64 is always ASCI)
+                [MethodImpl(MethodImplOptions.NoInlining)]
+                static string ToBase64StringLargeInputs(ReadOnlySpan<byte> data, int outputLen)
+                {
+                    Span<byte> utf8buffer = outputLen <= 256 ? stackalloc byte[256] : new byte[outputLen];
+                    OperationStatus status = Base64.EncodeToUtf8(data, utf8buffer, out int _, out int _);
+                    Debug.Assert(status == OperationStatus.Done);
+                    return Encoding.Latin1.GetString(utf8buffer);
+                }
+                return ToBase64StringLargeInputs(bytes, outputLength);
+            }
+
+            string result = string.FastAllocateString(outputLength);
 
             unsafe
             {