--- /dev/null
+// 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 Microsoft.Xunit.Performance;
+using Microsoft.Xunit.Performance.Api;
+using System;
+using System.Reflection;
+using Xunit;
+
+[assembly: OptimizeForBenchmarks]
+
+// Test code taken directly from GitHub issue #9692 (https://github.com/dotnet/coreclr/issues/9692)
+// Laying the loop's early return path in-line can cost 30% on this micro-benchmark.
+
+namespace Layout
+{
+ public unsafe class SearchLoops
+ {
+ public static int Main(string[] args)
+ {
+ // Make sure equal strings compare as such
+ if (!LoopReturn("hello", "hello") || !LoopGoto("goodbye", "goodbye"))
+ {
+ return -1;
+ }
+
+ // Make sure not-equal strings compare as such
+ if (LoopReturn("hello", "goodbye") || LoopGoto("goodbye", "hello"))
+ {
+ return -1;
+ }
+
+ // Success
+ return 100;
+ }
+
+ public int length = 100;
+
+ private string test1;
+ private string test2;
+
+ public SearchLoops()
+ {
+ test1 = new string('A', length);
+ test2 = new string('A', length);
+ }
+
+ [Benchmark]
+ public void LoopReturn()
+ {
+ Benchmark.Iterate(() => LoopReturn(test1, test2));
+ }
+
+ [Benchmark]
+ public void LoopGoto()
+ {
+ Benchmark.Iterate(() => LoopGoto(test1, test2));
+ }
+
+ // Variant with code written naturally -- need JIT to lay this out
+ // with return path out of loop for best performance.
+ public static bool LoopReturn(String strA, String strB)
+ {
+ int length = strA.Length;
+
+ fixed (char* ap = strA) fixed (char* bp = strB)
+ {
+ char* a = ap;
+ char* b = bp;
+
+ while (length != 0)
+ {
+ int charA = *a;
+ int charB = *b;
+
+ if (charA != charB)
+ return false; // placement of prolog for this return is the issue
+
+ a++;
+ b++;
+ length--;
+ }
+
+ return true;
+ }
+ }
+
+ // Variant with code written awkwardly but which acheives the desired
+ // performance if JIT simply lays out code in source order.
+ public static bool LoopGoto(String strA, String strB)
+ {
+ int length = strA.Length;
+
+ fixed (char* ap = strA) fixed (char* bp = strB)
+ {
+ char* a = ap;
+ char* b = bp;
+
+ while (length != 0)
+ {
+ int charA = *a;
+ int charB = *b;
+
+ if (charA != charB)
+ goto ReturnFalse; // placement of prolog for this return is the issue
+
+ a++;
+ b++;
+ length--;
+ }
+
+ return true;
+
+ ReturnFalse:
+ return false;
+ }
+ }
+ }
+}
--- /dev/null
+<?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>{C1BFD48A-A83F-4767-8EB2-3E2C50906681}</ProjectGuid>
+ <OutputType>Exe</OutputType>
+ <ProjectTypeGuids>{786C830F-07A1-408B-BD7F-6EE04809D6DB};{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}</ProjectTypeGuids>
+ <SolutionDir Condition="$(SolutionDir) == '' Or $(SolutionDir) == '*Undefined*'">..\..\</SolutionDir>
+ <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
+ </PropertyGroup>
+ <!-- Default configurations to help VS understand the configurations -->
+ <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
+ <DebugType>pdbonly</DebugType>
+ <Optimize>true</Optimize>
+ </PropertyGroup>
+ <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
+ <DebugType>pdbonly</DebugType>
+ <Optimize>true</Optimize>
+ </PropertyGroup>
+ <ItemGroup>
+ <CodeAnalysisDependentAssemblyPaths Condition=" '$(VS100COMNTOOLS)' != '' " Include="$(VS100COMNTOOLS)..\IDE\PrivateAssemblies">
+ <Visible>False</Visible>
+ </CodeAnalysisDependentAssemblyPaths>
+ </ItemGroup>
+ <ItemGroup>
+ <Service Include="{82A7F48D-3B50-4B1E-B82E-3ADA8210C358}" />
+ </ItemGroup>
+ <ItemGroup>
+ <Compile Include="SearchLoops.cs" />
+ </ItemGroup>
+ <Import Project="$([MSBuild]::GetDirectoryNameOfFileAbove($(MSBuildThisFileDirectory), dir.targets))\dir.targets" />
+ <PropertyGroup Condition=" '$(MsBuildProjectDirOverride)' != '' "></PropertyGroup>
+ <PropertyGroup>
+ <ProjectAssetsFile>$(JitPackagesConfigFileDirectory)benchmark\obj\project.assets.json</ProjectAssetsFile>
+ </PropertyGroup>
+</Project>