Factor out and improve the vectorization of RegexInterpreter.FindFirstChar

src/libraries/System.Text.RegularExpressions/gen/RegexGenerator.Parser.cs

@@ -178,7 +178,7 @@ private static bool IsSyntaxTargetForGeneration(SyntaxNode node) =>
             RegexCode code;
             try
             {
-                code = RegexWriter.Write(RegexParser.Parse(pattern, regexOptions, culture));
+                code = RegexWriter.Write(RegexParser.Parse(pattern, regexOptions, culture), culture);
             }
             catch (Exception e)
             {

src/libraries/System.Text.RegularExpressions/gen/Stubs.cs

@@ -54,13 +54,13 @@ namespace System.Threading
 {
     internal static class InterlockedExtensions
     {
-        public static int Or(ref int location1, int value)
+        public static uint Or(ref uint location1, uint value)
         {
-            int current = location1;
+            uint current = location1;
             while (true)
             {
-                int newValue = current | value;
-                int oldValue = Interlocked.CompareExchange(ref location1, newValue, current);
+                uint newValue = current | value;
+                uint oldValue = (uint)Interlocked.CompareExchange(ref Unsafe.As<uint, int>(ref location1), (int)newValue, (int)current);
                 if (oldValue == current)
                 {
                     return oldValue;

src/libraries/System.Text.RegularExpressions/gen/System.Text.RegularExpressions.Generator.csproj

@@ -30,10 +30,10 @@
     <Compile Include="$(CoreLibSharedDir)System\Collections\Generic\ValueListBuilder.cs" Link="Production\ValueListBuilder.cs" />
     <Compile Include="..\src\System\Collections\Generic\ValueListBuilder.Pop.cs" Link="Production\ValueListBuilder.Pop.cs" />
     <Compile Include="..\src\System\Threading\StackHelper.cs" Link="Production\StackHelper.cs" />
-    <Compile Include="..\src\System\Text\RegularExpressions\RegexBoyerMoore.cs" Link="Production\RegexBoyerMoore.cs" />
     <Compile Include="..\src\System\Text\RegularExpressions\RegexCharClass.cs" Link="Production\RegexCharClass.cs" />
     <Compile Include="..\src\System\Text\RegularExpressions\RegexCharClass.MappingTable.cs" Link="Production\RegexCharClass.MappingTable.cs" />
     <Compile Include="..\src\System\Text\RegularExpressions\RegexCode.cs" Link="Production\RegexCode.cs" />
+    <Compile Include="..\src\System\Text\RegularExpressions\RegexFindOptimizations.cs" Link="Production\RegexFindOptimizations.cs" />
     <Compile Include="..\src\System\Text\RegularExpressions\RegexNode.cs" Link="Production\RegexNode.cs" />
     <Compile Include="..\src\System\Text\RegularExpressions\RegexOptions.cs" Link="Production\RegexOptions.cs" />
     <Compile Include="..\src\System\Text\RegularExpressions\RegexParseError.cs" Link="Production\RegexParseError.cs" />

src/libraries/System.Text.RegularExpressions/src/System.Text.RegularExpressions.csproj

@@ -23,11 +23,11 @@
     <Compile Include="System\Text\RegularExpressions\Regex.Replace.cs" />
     <Compile Include="System\Text\RegularExpressions\Regex.Split.cs" />
     <Compile Include="System\Text\RegularExpressions\Regex.Timeout.cs" />
-    <Compile Include="System\Text\RegularExpressions\RegexBoyerMoore.cs" />
     <Compile Include="System\Text\RegularExpressions\RegexCharClass.cs" />
     <Compile Include="System\Text\RegularExpressions\RegexCharClass.MappingTable.cs" />
     <Compile Include="System\Text\RegularExpressions\RegexCode.cs" />
     <Compile Include="System\Text\RegularExpressions\RegexCompilationInfo.cs" />
+    <Compile Include="System\Text\RegularExpressions\RegexFindOptimizations.cs" />
     <Compile Include="System\Text\RegularExpressions\RegexGeneratorAttribute.cs" />
     <Compile Include="System\Text\RegularExpressions\RegexInterpreter.cs" />
     <Compile Include="System\Text\RegularExpressions\RegexMatchTimeoutException.cs" />
@@ -100,6 +100,7 @@
     <Reference Include="System.Memory" />
     <Reference Include="System.Runtime" />
     <Reference Include="System.Runtime.Extensions" />
+    <Reference Include="System.Runtime.InteropServices" />
     <Reference Include="System.Threading" />
     <!-- References required for RegexOptions.Compiled -->
     <Reference Include="System.Reflection.Emit" />

src/libraries/System.Text.RegularExpressions/src/System/Text/RegularExpressions/Regex.Cache.cs

@@ -128,7 +128,7 @@ public static Regex GetOrAdd(string pattern, RegexOptions options, TimeSpan matc
             Regex.ValidateOptions(options);
             Regex.ValidateMatchTimeout(matchTimeout);
 
-            CultureInfo culture = (options & RegexOptions.CultureInvariant) != 0 ? CultureInfo.InvariantCulture : CultureInfo.CurrentCulture;
+            CultureInfo culture = RegexParser.GetTargetCulture(options);
             Key key = new Key(pattern, culture.ToString(), options, matchTimeout);
 
             Regex? regex = Get(key);

src/libraries/System.Text.RegularExpressions/src/System/Text/RegularExpressions/Regex.cs

@@ -65,12 +65,12 @@ internal Regex(string pattern, CultureInfo? culture)
             // Call Init directly rather than delegating to a Regex ctor that takes
             // options to enable linking / tree shaking to remove the Regex compiler
             // and NonBacktracking implementation if it's not used.
-            Init(pattern, RegexOptions.None, s_defaultMatchTimeout, culture);
+            Init(pattern, RegexOptions.None, s_defaultMatchTimeout, culture ?? CultureInfo.CurrentCulture);
         }
 
         internal Regex(string pattern, RegexOptions options, TimeSpan matchTimeout, CultureInfo? culture)
         {
-            culture ??= GetTargetCulture(options);
+            culture ??= RegexParser.GetTargetCulture(options);
             Init(pattern, options, matchTimeout, culture);
 
             if ((options & RegexOptions.NonBacktracking) != 0)
@@ -87,18 +87,14 @@ internal Regex(string pattern, RegexOptions options, TimeSpan matchTimeout, Cult
             }
         }
 
-        /// <summary>Gets the culture to use based on the specified options.</summary>
-        private static CultureInfo GetTargetCulture(RegexOptions options) =>
-            (options & RegexOptions.CultureInvariant) != 0 ? CultureInfo.InvariantCulture : CultureInfo.CurrentCulture;
-
         /// <summary>Initializes the instance.</summary>
         /// <remarks>
         /// This is separated out of the constructor so that an app only using 'new Regex(pattern)'
         /// rather than 'new Regex(pattern, options)' can avoid statically referencing the Regex
         /// compiler, such that a tree shaker / linker can trim it away if it's not otherwise used.
         /// </remarks>
         [MemberNotNull(nameof(_code))]
-        private void Init(string pattern, RegexOptions options, TimeSpan matchTimeout, CultureInfo? culture)
+        private void Init(string pattern, RegexOptions options, TimeSpan matchTimeout, CultureInfo culture)
         {
             ValidatePattern(pattern);
             ValidateOptions(options);
@@ -107,7 +103,6 @@ private void Init(string pattern, RegexOptions options, TimeSpan matchTimeout, C
             this.pattern = pattern;
             internalMatchTimeout = matchTimeout;
             roptions = options;
-            culture ??= GetTargetCulture(options);
 
 #if DEBUG
             if (IsDebug)
@@ -121,7 +116,7 @@ private void Init(string pattern, RegexOptions options, TimeSpan matchTimeout, C
 
             // Generate the RegexCode from the node tree.  This is required for interpreting,
             // and is used as input into RegexOptions.Compiled and RegexOptions.NonBacktracking.
-            _code = RegexWriter.Write(tree);
+            _code = RegexWriter.Write(tree, culture);
 
             if ((options & RegexOptions.NonBacktracking) != 0)
             {
@@ -434,7 +429,7 @@ internal void Run<TState>(string input, int startat, ref TState state, MatchCall
         /// <summary>Creates a new runner instance.</summary>
         private RegexRunner CreateRunner() =>
             factory?.CreateInstance() ??
-            new RegexInterpreter(_code!, GetTargetCulture(roptions));
+            new RegexInterpreter(_code!, RegexParser.GetTargetCulture(roptions));
 
         /// <summary>True if the <see cref="RegexOptions.Compiled"/> option was set.</summary>
         protected bool UseOptionC() => (roptions & RegexOptions.Compiled) != 0;