Add support for BSWAP intrinsic (#18398)

With this change, the JIT will recognize a call to BinaryPrimitives.ReverseEndianness and will emit a bswap instruction.
This logic is currently only hooked up for x86 and x64; ARM still uses fallback logic.
If the JIT can't emit a bswap instruction (for example, trying to emit a 64-bit bswap in a 32-bit process), it will fall back to a software implementation, so the APIs will work across all architectures.

3 files changed, 206 insertions, 0 deletions

diff --git a/tests/src/JIT/Intrinsics/BinaryPrimitivesReverseEndianness.cs b/tests/src/JIT/Intrinsics/BinaryPrimitivesReverseEndianness.cs
new file mode 100644
index 0000000000..b650fc8982
--- /dev/null
+++ b/tests/src/JIT/Intrinsics/BinaryPrimitivesReverseEndianness.cs
@@ -0,0 +1,136 @@
+// 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.
+//
+
+using System;
+using System.Buffers.Binary;
+using Internal;
+
+namespace BinaryPrimitivesReverseEndianness
+{
+    class Program
+    {
+        public const int Pass = 100;
+        public const int Fail = 0;
+
+        private const ushort ConstantUInt16Input = 0x9876;
+        private const ushort ConstantUInt16Expected = 0x7698;
+
+        private const uint ConstantUInt32Input = 0x98765432;
+        private const uint ConstantUInt32Expected = 0x32547698;
+
+        private const ulong ConstantUInt64Input = 0xfedcba9876543210;
+        private const ulong ConstantUInt64Expected = 0x1032547698badcfe;
+
+
+        static int Main(string[] args)
+        {
+            /*
+             * CONST VALUE TESTS
+             */
+
+            ushort swappedUInt16 = BinaryPrimitives.ReverseEndianness(ConstantUInt16Input);
+            if (swappedUInt16 != ConstantUInt16Expected)
+            {
+                Console.WriteLine($"BinaryPrimitives.ReverseEndianness(const UInt16) failed.");
+                Console.WriteLine($"Input:    0x{ConstantUInt16Input:X4}");
+                Console.WriteLine($"Output:   0x{swappedUInt16:X4}");
+                Console.WriteLine($"Expected: 0x{ConstantUInt16Expected:X4}");
+            }
+
+            uint swappedUInt32 = BinaryPrimitives.ReverseEndianness(ConstantUInt32Input);
+            if (swappedUInt32 != ConstantUInt32Expected)
+            {
+                Console.WriteLine($"BinaryPrimitives.ReverseEndianness(const UInt32) failed.");
+                Console.WriteLine($"Input:    0x{ConstantUInt32Input:X8}");
+                Console.WriteLine($"Output:   0x{swappedUInt32:X8}");
+                Console.WriteLine($"Expected: 0x{ConstantUInt32Expected:X8}");
+            }
+
+            ulong swappedUInt64 = BinaryPrimitives.ReverseEndianness(ConstantUInt64Input);
+            if (swappedUInt64 != ConstantUInt64Expected)
+            {
+                Console.WriteLine($"BinaryPrimitives.ReverseEndianness(const UInt32) failed.");
+                Console.WriteLine($"Input:    0x{ConstantUInt64Input:X16}");
+                Console.WriteLine($"Output:   0x{swappedUInt64:X16}");
+                Console.WriteLine($"Expected: 0x{ConstantUInt64Expected:X16}");
+            }
+
+            /*
+             * NON-CONST VALUE TESTS
+             */
+
+            ushort nonConstUInt16Input = (ushort)DateTime.UtcNow.Ticks;
+            ushort nonConstUInt16Output = BinaryPrimitives.ReverseEndianness(nonConstUInt16Input);
+            ushort nonConstUInt16Expected = ByteSwapUInt16_Control(nonConstUInt16Input);
+            if (nonConstUInt16Output != nonConstUInt16Expected)
+            {
+                Console.WriteLine($"BinaryPrimitives.ReverseEndianness(non-const UInt16) failed.");
+                Console.WriteLine($"Input:    0x{nonConstUInt16Input:X4}");
+                Console.WriteLine($"Output:   0x{nonConstUInt16Output:X4}");
+                Console.WriteLine($"Expected: 0x{nonConstUInt16Expected:X4}");
+            }
+
+            uint nonConstUInt32Input = (uint)DateTime.UtcNow.Ticks;
+            uint nonConstUInt32Output = BinaryPrimitives.ReverseEndianness(nonConstUInt32Input);
+            uint nonConstUInt32Expected = ByteSwapUInt32_Control(nonConstUInt32Input);
+            if (nonConstUInt32Output != nonConstUInt32Expected)
+            {
+                Console.WriteLine($"BinaryPrimitives.ReverseEndianness(non-const UInt32) failed.");
+                Console.WriteLine($"Input:    0x{nonConstUInt32Input:X8}");
+                Console.WriteLine($"Output:   0x{nonConstUInt32Output:X8}");
+                Console.WriteLine($"Expected: 0x{nonConstUInt32Expected:X8}");
+            }
+
+            ulong nonConstUInt64Input = (ulong)DateTime.UtcNow.Ticks;
+            ulong nonConstUInt64Output = BinaryPrimitives.ReverseEndianness(nonConstUInt64Input);
+            ulong nonConstUInt64Expected = ByteSwapUInt64_Control(nonConstUInt64Input);
+            if (nonConstUInt64Output != nonConstUInt64Expected)
+            {
+                Console.WriteLine($"BinaryPrimitives.ReverseEndianness(non-const UInt64) failed.");
+                Console.WriteLine($"Input:    0x{nonConstUInt64Input:X16}");
+                Console.WriteLine($"Output:   0x{nonConstUInt64Output:X16}");
+                Console.WriteLine($"Expected: 0x{nonConstUInt64Expected:X16}");
+            }
+
+            return Pass;
+        }
+
+        private static ushort ByteSwapUInt16_Control(ushort value)
+        {
+            return (ushort)ByteSwapUnsigned_General(value, sizeof(ushort));
+        }
+
+        private static uint ByteSwapUInt32_Control(uint value)
+        {
+            return (uint)ByteSwapUnsigned_General(value, sizeof(uint));
+        }
+
+        private static ulong ByteSwapUInt64_Control(ulong value)
+        {
+            return (ulong)ByteSwapUnsigned_General(value, sizeof(ulong));
+        }
+
+        private static ulong ByteSwapUnsigned_General(ulong value, int width)
+        {
+            // A naive byte swap routine that works on integers of any arbitrary width.
+            // Width is specified in bytes.
+
+            ulong retVal = 0;
+            do
+            {
+                retVal = retVal << 8 | (byte)value;
+                value >>= 8;
+            } while (--width > 0);
+
+            if (value != 0)
+            {
+                // All bits of value should've been shifted out at this point.
+                throw new Exception("Unexpected data width specified - error in test program?");
+            }
+
+            return retVal;
+        }
+    }
+}
diff --git a/tests/src/JIT/Intrinsics/BinaryPrimitivesReverseEndianness_r.csproj b/tests/src/JIT/Intrinsics/BinaryPrimitivesReverseEndianness_r.csproj
new file mode 100644
index 0000000000..32ddef9c5a
--- /dev/null
+++ b/tests/src/JIT/Intrinsics/BinaryPrimitivesReverseEndianness_r.csproj
@@ -0,0 +1,35 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project ToolsVersion="12.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <Import Project="$([MSBuild]::GetDirectoryNameOfFileAbove($(MSBuildThisFileDirectory), dir.props))\dir.props" />
+  <PropertyGroup>
+    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
+    <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
+    <SchemaVersion>2.0</SchemaVersion>
+    <ProjectGuid>{95DFC527-4DC1-495E-97D7-E94EE1F7140D}</ProjectGuid>
+    <OutputType>Exe</OutputType>
+    <ProjectTypeGuids>{786C830F-07A1-408B-BD7F-6EE04809D6DB};{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}</ProjectTypeGuids>
+    <SolutionDir Condition="$(SolutionDir) == '' Or $(SolutionDir) == '*Undefined*'">..\..\</SolutionDir>
+    <ReferenceSystemPrivateCoreLib>true</ReferenceSystemPrivateCoreLib>
+  </PropertyGroup>
+  <!-- Default configurations to help VS understand the configurations -->
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' "></PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' " />
+  <ItemGroup>
+    <CodeAnalysisDependentAssemblyPaths Condition=" '$(VS100COMNTOOLS)' != '' " Include="$(VS100COMNTOOLS)..\IDE\PrivateAssemblies">
+      <Visible>False</Visible>
+    </CodeAnalysisDependentAssemblyPaths>
+  </ItemGroup>
+  <PropertyGroup>
+    <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
+    <DebugType>None</DebugType>
+    <Optimize></Optimize>
+  </PropertyGroup>
+  <ItemGroup>
+    <Service Include="{82A7F48D-3B50-4B1E-B82E-3ADA8210C358}" />
+  </ItemGroup>
+  <ItemGroup>
+    <Compile Include="BinaryPrimitivesReverseEndianness.cs" />
+  </ItemGroup>
+  <Import Project="$([MSBuild]::GetDirectoryNameOfFileAbove($(MSBuildThisFileDirectory), dir.targets))\dir.targets" />
+  <PropertyGroup Condition=" '$(MsBuildProjectDirOverride)' != '' "></PropertyGroup>
+</Project>
diff --git a/tests/src/JIT/Intrinsics/BinaryPrimitivesReverseEndianness_ro.csproj b/tests/src/JIT/Intrinsics/BinaryPrimitivesReverseEndianness_ro.csproj
new file mode 100644
index 0000000000..ca7ce2184e
--- /dev/null
+++ b/tests/src/JIT/Intrinsics/BinaryPrimitivesReverseEndianness_ro.csproj
@@ -0,0 +1,35 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project ToolsVersion="12.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <Import Project="$([MSBuild]::GetDirectoryNameOfFileAbove($(MSBuildThisFileDirectory), dir.props))\dir.props" />
+  <PropertyGroup>
+    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
+    <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
+    <SchemaVersion>2.0</SchemaVersion>
+    <ProjectGuid>{95DFC527-4DC1-495E-97D7-E94EE1F7140D}</ProjectGuid>
+    <OutputType>Exe</OutputType>
+    <ProjectTypeGuids>{786C830F-07A1-408B-BD7F-6EE04809D6DB};{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}</ProjectTypeGuids>
+    <SolutionDir Condition="$(SolutionDir) == '' Or $(SolutionDir) == '*Undefined*'">..\..\</SolutionDir>
+    <ReferenceSystemPrivateCoreLib>true</ReferenceSystemPrivateCoreLib>
+  </PropertyGroup>
+  <!-- Default configurations to help VS understand the configurations -->
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' "></PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' " />
+  <ItemGroup>
+    <CodeAnalysisDependentAssemblyPaths Condition=" '$(VS100COMNTOOLS)' != '' " Include="$(VS100COMNTOOLS)..\IDE\PrivateAssemblies">
+      <Visible>False</Visible>
+    </CodeAnalysisDependentAssemblyPaths>
+  </ItemGroup>
+  <PropertyGroup>
+    <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
+    <DebugType>None</DebugType>
+    <Optimize>True</Optimize>
+  </PropertyGroup>
+  <ItemGroup>
+    <Service Include="{82A7F48D-3B50-4B1E-B82E-3ADA8210C358}" />
+  </ItemGroup>
+  <ItemGroup>
+    <Compile Include="BinaryPrimitivesReverseEndianness.cs" />
+  </ItemGroup>
+  <Import Project="$([MSBuild]::GetDirectoryNameOfFileAbove($(MSBuildThisFileDirectory), dir.targets))\dir.targets" />
+  <PropertyGroup Condition=" '$(MsBuildProjectDirOverride)' != '' "></PropertyGroup>
+</Project>