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React to CheckForOverflowUnderflow in regex source generator #78228

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merged 2 commits into from
Nov 11, 2022
Merged

React to CheckForOverflowUnderflow in regex source generator #78228

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727c872
React to CheckForOverflowUnderflow in regex source generator
stephentoub Nov 11, 2022
04a2add
Address PR feedback
stephentoub Nov 11, 2022
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90 changes: 58 additions & 32 deletions src/libraries/System.Text.RegularExpressions/gen/RegexGenerator.Emitter.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -172,8 +172,27 @@ static void AppendHashtableContents(IndentedTextWriter writer, IEnumerable<Dicti
}

/// <summary>Emits the code for the RunnerFactory. This is the actual logic for the regular expression.</summary>
private static void EmitRegexDerivedTypeRunnerFactory(IndentedTextWriter writer, RegexMethod rm, Dictionary<string, string[]> requiredHelpers)
private static void EmitRegexDerivedTypeRunnerFactory(IndentedTextWriter writer, RegexMethod rm, Dictionary<string, string[]> requiredHelpers, bool checkOverflow)
{
void EnterCheckOverflow()
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NIT: no need to reset CI for this, but I think it is a bit more readable in general when we have local funcs at the end of the method (even better if they are after a return statement)

{
if (checkOverflow)
{
writer.WriteLine($"unchecked");
writer.WriteLine($"{{");
writer.Indent++;
}
}

void ExitCheckOverflow()
{
if (checkOverflow)
{
writer.Indent--;
writer.WriteLine($"}}");
}
}

writer.WriteLine($"/// <summary>Provides a factory for creating <see cref=\"RegexRunner\"/> instances to be used by methods on <see cref=\"Regex\"/>.</summary>");
writer.WriteLine($"private sealed class RunnerFactory : RegexRunnerFactory");
writer.WriteLine($"{{");
Expand Down Expand Up @@ -208,7 +227,9 @@ private static void EmitRegexDerivedTypeRunnerFactory(IndentedTextWriter writer,
writer.WriteLine($" protected override void Scan(ReadOnlySpan<char> inputSpan)");
writer.WriteLine($" {{");
writer.Indent += 3;
EnterCheckOverflow();
(bool needsTryFind, bool needsTryMatch) = EmitScan(writer, rm);
ExitCheckOverflow();
writer.Indent -= 3;
writer.WriteLine($" }}");
if (needsTryFind)
Expand All @@ -220,7 +241,9 @@ private static void EmitRegexDerivedTypeRunnerFactory(IndentedTextWriter writer,
writer.WriteLine($" private bool TryFindNextPossibleStartingPosition(ReadOnlySpan<char> inputSpan)");
writer.WriteLine($" {{");
writer.Indent += 3;
EnterCheckOverflow();
EmitTryFindNextPossibleStartingPosition(writer, rm, requiredHelpers);
ExitCheckOverflow();
writer.Indent -= 3;
writer.WriteLine($" }}");
}
Expand All @@ -233,7 +256,9 @@ private static void EmitRegexDerivedTypeRunnerFactory(IndentedTextWriter writer,
writer.WriteLine($" private bool TryMatchAtCurrentPosition(ReadOnlySpan<char> inputSpan)");
writer.WriteLine($" {{");
writer.Indent += 3;
EmitTryMatchAtCurrentPosition(writer, rm, requiredHelpers);
EnterCheckOverflow();
EmitTryMatchAtCurrentPosition(writer, rm, requiredHelpers, checkOverflow);
ExitCheckOverflow();
writer.Indent -= 3;
writer.WriteLine($" }}");
}
Expand Down Expand Up @@ -288,51 +313,52 @@ private static void AddIsWordCharHelper(Dictionary<string, string[]> requiredHel
}

/// <summary>Adds the IsBoundary helper to the required helpers collection.</summary>
private static void AddIsBoundaryHelper(Dictionary<string, string[]> requiredHelpers)
private static void AddIsBoundaryHelper(Dictionary<string, string[]> requiredHelpers, bool checkOverflow)
{
const string IsBoundary = nameof(IsBoundary);
if (!requiredHelpers.ContainsKey(IsBoundary))
{
string uncheckedKeyword = checkOverflow ? "unchecked" : "";
requiredHelpers.Add(IsBoundary, new string[]
{
"/// <summary>Determines whether the specified index is a boundary.</summary>",
"[MethodImpl(MethodImplOptions.AggressiveInlining)]",
"internal static bool IsBoundary(ReadOnlySpan<char> inputSpan, int index)",
"{",
" int indexMinus1 = index - 1;",
" return ((uint)indexMinus1 < (uint)inputSpan.Length && IsBoundaryWordChar(inputSpan[indexMinus1])) !=",
" ((uint)index < (uint)inputSpan.Length && IsBoundaryWordChar(inputSpan[index]));",
"",
" static bool IsBoundaryWordChar(char ch) => IsWordChar(ch) || (ch == '\\u200C' | ch == '\\u200D');",
"}",
$"/// <summary>Determines whether the specified index is a boundary.</summary>",
$"[MethodImpl(MethodImplOptions.AggressiveInlining)]",
$"internal static bool IsBoundary(ReadOnlySpan<char> inputSpan, int index)",
$"{{",
$" int indexMinus1 = index - 1;",
$" return {uncheckedKeyword}((uint)indexMinus1 < (uint)inputSpan.Length && IsBoundaryWordChar(inputSpan[indexMinus1])) !=",
$" {uncheckedKeyword}((uint)index < (uint)inputSpan.Length && IsBoundaryWordChar(inputSpan[index]));",
$"",
$" static bool IsBoundaryWordChar(char ch) => IsWordChar(ch) || (ch == '\\u200C' | ch == '\\u200D');",
$"}}",
});

AddIsWordCharHelper(requiredHelpers);
}
}

/// <summary>Adds the IsECMABoundary helper to the required helpers collection.</summary>
private static void AddIsECMABoundaryHelper(Dictionary<string, string[]> requiredHelpers)
private static void AddIsECMABoundaryHelper(Dictionary<string, string[]> requiredHelpers, bool checkOverflow)
{
const string IsECMABoundary = nameof(IsECMABoundary);
if (!requiredHelpers.ContainsKey(IsECMABoundary))
{
string uncheckedKeyword = checkOverflow ? "unchecked" : "";
requiredHelpers.Add(IsECMABoundary, new string[]
{
"/// <summary>Determines whether the specified index is a boundary (ECMAScript).</summary>",
"[MethodImpl(MethodImplOptions.AggressiveInlining)]",
"internal static bool IsECMABoundary(ReadOnlySpan<char> inputSpan, int index)",
"{",
" int indexMinus1 = index - 1;",
" return ((uint)indexMinus1 < (uint)inputSpan.Length && IsECMAWordChar(inputSpan[indexMinus1])) !=",
" ((uint)index < (uint)inputSpan.Length && IsECMAWordChar(inputSpan[index]));",
"",
" static bool IsECMAWordChar(char ch) =>",
" ((((uint)ch - 'A') & ~0x20) < 26) || // ASCII letter",
" (((uint)ch - '0') < 10) || // digit",
" ch == '_' || // underscore",
" ch == '\\u0130'; // latin capital letter I with dot above",
"}",
$"/// <summary>Determines whether the specified index is a boundary (ECMAScript).</summary>",
$"[MethodImpl(MethodImplOptions.AggressiveInlining)]",
$"internal static bool IsECMABoundary(ReadOnlySpan<char> inputSpan, int index)",
$"{{",
$" int indexMinus1 = index - 1;",
$" return {uncheckedKeyword}((uint)indexMinus1 < (uint)inputSpan.Length && IsECMAWordChar(inputSpan[indexMinus1])) !=",
$" {uncheckedKeyword}((uint)index < (uint)inputSpan.Length && IsECMAWordChar(inputSpan[index]));",
$"",
$" static bool IsECMAWordChar(char ch) =>",
$" char.IsAsciiLetterOrDigit(ch) ||",
$" ch == '_' ||",
$" ch == '\\u0130'; // latin capital letter I with dot above",
$"}}",
});
}
}
Expand Down Expand Up @@ -426,7 +452,7 @@ FindNextStartingPositionMode.LeadingAnchor_RightToLeft_Start or
/// <summary>Emits the body of the TryFindNextPossibleStartingPosition.</summary>
private static void EmitTryFindNextPossibleStartingPosition(IndentedTextWriter writer, RegexMethod rm, Dictionary<string, string[]> requiredHelpers)
{
RegexOptions options = (RegexOptions)rm.Options;
RegexOptions options = rm.Options;
RegexTree regexTree = rm.Tree;
bool rtl = (options & RegexOptions.RightToLeft) != 0;

Expand Down Expand Up @@ -1034,7 +1060,7 @@ void EmitLiteralAfterAtomicLoop()
}

/// <summary>Emits the body of the TryMatchAtCurrentPosition.</summary>
private static void EmitTryMatchAtCurrentPosition(IndentedTextWriter writer, RegexMethod rm, Dictionary<string, string[]> requiredHelpers)
private static void EmitTryMatchAtCurrentPosition(IndentedTextWriter writer, RegexMethod rm, Dictionary<string, string[]> requiredHelpers, bool checkOverflow)
{
// In .NET Framework and up through .NET Core 3.1, the code generated for RegexOptions.Compiled was effectively an unrolled
// version of what RegexInterpreter would process. The RegexNode tree would be turned into a series of opcodes via
Expand Down Expand Up @@ -2677,14 +2703,14 @@ void EmitBoundary(RegexNode node)
call = node.Kind is RegexNodeKind.Boundary ?
$"!{HelpersTypeName}.IsBoundary" :
$"{HelpersTypeName}.IsBoundary";
AddIsBoundaryHelper(requiredHelpers);
AddIsBoundaryHelper(requiredHelpers, checkOverflow);
}
else
{
call = node.Kind is RegexNodeKind.ECMABoundary ?
$"!{HelpersTypeName}.IsECMABoundary" :
$"{HelpersTypeName}.IsECMABoundary";
AddIsECMABoundaryHelper(requiredHelpers);
AddIsECMABoundaryHelper(requiredHelpers, checkOverflow);
}

using (EmitBlock(writer, $"if ({call}(inputSpan, pos{(sliceStaticPos > 0 ? $" + {sliceStaticPos}" : "")}))"))
Expand Down
41 changes: 23 additions & 18 deletions src/libraries/System.Text.RegularExpressions/gen/RegexGenerator.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -36,13 +36,24 @@ public partial class RegexGenerator : IIncrementalGenerator
"#pragma warning disable CS0219 // Variable assigned but never used",
};

private record struct CompilationData(bool AllowUnsafe, bool CheckOverflow);

public void Initialize(IncrementalGeneratorInitializationContext context)
{
// To avoid invalidating every regex's output when anything from the compilation changes,
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// we extract from it the only things we care about.
IncrementalValueProvider<CompilationData> compilationDataProvider =
context.CompilationProvider
.Select((x, _) =>
x.Options is CSharpCompilationOptions options ?
new CompilationData(options.AllowUnsafe, options.CheckOverflow) :
default);

// Produces one entry per generated regex. This may be:
// - Diagnostic in the case of a failure that should end the compilation
// - (RegexMethod regexMethod, string runnerFactoryImplementation, Dictionary<string, string[]> requiredHelpers) in the case of valid regex
// - (RegexMethod regexMethod, string reason, Diagnostic diagnostic) in the case of a limited-support regex
IncrementalValueProvider<ImmutableArray<object>> codeOrDiagnostics =
IncrementalValueProvider<ImmutableArray<object>> results =
context.SyntaxProvider

// Find all MethodDeclarationSyntax nodes attributed with GeneratedRegex and gather the required information.
Expand All @@ -52,9 +63,13 @@ public void Initialize(IncrementalGeneratorInitializationContext context)
GetSemanticTargetForGeneration)
.Where(static m => m is not null)

// Incorporate the compilation data, as it impacts code generation.
.Combine(compilationDataProvider)

// Generate the RunnerFactory for each regex, if possible. This is where the bulk of the implementation occurs.
.Select((state, _) =>
.Select((methodOrDiagnosticAndCompilationData, _) =>
{
object? state = methodOrDiagnosticAndCompilationData.Left;
if (state is not RegexMethod regexMethod)
{
Debug.Assert(state is Diagnostic);
Expand All @@ -74,26 +89,16 @@ public void Initialize(IncrementalGeneratorInitializationContext context)
var writer = new IndentedTextWriter(sw);
writer.Indent += 2;
writer.WriteLine();
EmitRegexDerivedTypeRunnerFactory(writer, regexMethod, requiredHelpers);
EmitRegexDerivedTypeRunnerFactory(writer, regexMethod, requiredHelpers, methodOrDiagnosticAndCompilationData.Right.CheckOverflow);
writer.Indent -= 2;
return (regexMethod, sw.ToString(), requiredHelpers);
return (regexMethod, sw.ToString(), requiredHelpers, methodOrDiagnosticAndCompilationData.Right);
})
.Collect();

// To avoid invalidating every regex's output when anything from the compilation changes,
// we extract from it the only things we care about: whether unsafe code is allowed,
// and a name based on the assembly's name, and only that information is then fed into
// RegisterSourceOutput along with all of the cached generated data from each regex.
IncrementalValueProvider<(bool AllowUnsafe, string? AssemblyName)> compilationDataProvider =
context.CompilationProvider
.Select((x, _) => (x.Options is CSharpCompilationOptions { AllowUnsafe: true }, x.AssemblyName));

// When there something to output, take all the generated strings and concatenate them to output,
// and raise all of the created diagnostics.
context.RegisterSourceOutput(codeOrDiagnostics.Combine(compilationDataProvider), static (context, compilationDataAndResults) =>
context.RegisterSourceOutput(results, static (context, results) =>
{
ImmutableArray<object> results = compilationDataAndResults.Left;

// Report any top-level diagnostics.
bool allFailures = true;
foreach (object result in results)
Expand Down Expand Up @@ -150,7 +155,7 @@ public void Initialize(IncrementalGeneratorInitializationContext context)
context.ReportDiagnostic(limitedSupportResult.Item3);
regexMethod = limitedSupportResult.Item1;
}
else if (result is ValueTuple<RegexMethod, string, Dictionary<string, string[]>> regexImpl)
else if (result is ValueTuple<RegexMethod, string, Dictionary<string, string[]>, CompilationData> regexImpl)
{
foreach (KeyValuePair<string, string[]> helper in regexImpl.Item3)
{
Expand Down Expand Up @@ -214,11 +219,11 @@ public void Initialize(IncrementalGeneratorInitializationContext context)
writer.WriteLine();
}
}
else if (result is ValueTuple<RegexMethod, string, Dictionary<string, string[]>> regexImpl)
else if (result is ValueTuple<RegexMethod, string, Dictionary<string, string[]>, CompilationData> regexImpl)
{
if (!regexImpl.Item1.IsDuplicate)
{
EmitRegexDerivedImplementation(writer, regexImpl.Item1, regexImpl.Item2, compilationDataAndResults.Right.AllowUnsafe);
EmitRegexDerivedImplementation(writer, regexImpl.Item1, regexImpl.Item2, regexImpl.Item4.AllowUnsafe);
writer.WriteLine();
}
}
Expand Down
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