Add SimpleCaseFoldTest

Author: iSazonov

src/SimpleCaseFolding.cs

@@ -40,6 +40,28 @@ public static char SimpleCaseFold(char c)
             return ch == 0 ? c : ch;
         }
 
+        /// <summary>
+        /// Simple case fold the char.
+        /// </summary>
+        /// <param name="c">Source char.</param>
+        /// <returns>
+        /// Returns folded char.
+        /// </returns>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static char SimpleCaseFoldTest(char c)
+        {
+            if (c < MapBelow5FF.Length)
+            {
+                return MapBelow5FF[c];
+            }
+
+            // Still slow due to border checks.
+            ushort v = Unsafe.Add(ref s_MapLevel1, c >> 8);
+            char ch = Unsafe.Add(ref s_refMapData, v + (c & 0xFF));
+
+            return ch == 0 ? c : ch;
+        }
+
         // Mapping for chars > 0x5ff slowly due to 2-level mapping.
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         private static int SimpleCaseFoldCompareAbove05ff(char c1, char c2, ref ushort refMapLevel1, ref char refMapData)

tests/Benchmarks/StringFolding/Perf.StringFolding.cs

@@ -10,6 +10,10 @@
 using System.Security.Cryptography;
 
 using BenchmarkDotNet.Attributes;
+using BenchmarkDotNet.Configs;
+using BenchmarkDotNet.Jobs;
+using BenchmarkDotNet.Toolchains.CsProj;
+using BenchmarkDotNet.Toolchains.DotNetCli;
 using BenchmarkDotNet.Running;
 
 namespace System.Text.CaseFolding
@@ -18,12 +22,46 @@ public class Program
     {
         public static void Main(string[] args)
         {
-            var summary = BenchmarkRunner.Run<StringFoldingBenchmark>();
+            var summary = BenchmarkRunner.Run<StringFoldingBenchmark_SimpleCaseFold>();
             Console.WriteLine("Result: {0}", SimpleCaseFolding.SimpleCaseFold("cASEfOLDING2"));
             Console.WriteLine("Result: {0}", SimpleCaseFolding.SimpleCaseFold("яЯяЯяЯяЯяЯя2"));
         }
     }
 
+    [DisassemblyDiagnoser(printAsm: true, printSource: true, recursiveDepth: 2)]
+    [Config(typeof(ConfigWithCustomEnvVars))]
+    public class StringFoldingBenchmark_SimpleCaseFold
+    {
+        private class ConfigWithCustomEnvVars : ManualConfig
+        {
+             private const string JitNoInline = "COMPlus_TieredCompilation";
+
+            public ConfigWithCustomEnvVars()
+            {
+                Add(Job.Core
+                    .With(new[] { new EnvironmentVariable(JitNoInline, "1") })
+                    .WithTargetCount(20)
+                    .WithUnrollFactor(20)
+                    .With(CsProjCoreToolchain.From(NetCoreAppSettings.NetCoreApp30)));
+            }
+        }
+
+        [Params('A', '\u0600')]
+        public char TestChar { get; set; }
+
+        [Benchmark(Baseline = true)]
+        public char SimpleCaseFold()
+        {
+            return SimpleCaseFolding.SimpleCaseFold(TestChar);
+        }
+
+        [Benchmark]
+        public char SimpleCaseFoldTest()
+        {
+            return SimpleCaseFolding.SimpleCaseFoldTest(TestChar);
+        }
+    }
+
     [DisassemblyDiagnoser(printAsm: true, printSource: true, recursiveDepth: 3)]
     public class StringFoldingBenchmark
     {