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Reduce allocations in AnalyzerFileReference.GetAnalyzerTypeNameMap #74411

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Merged
ToddGrun merged 1 commit into from
Jul 18, 2024
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Reduce allocations in AnalyzerFileReference.GetAnalyzerTypeNameMap #74411

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65 changes: 40 additions & 25 deletions src/Compilers/Core/Portable/DiagnosticAnalyzer/AnalyzerFileReference.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -31,7 +31,7 @@ namespace Microsoft.CodeAnalysis.Diagnostics
/// </remarks>
public sealed class AnalyzerFileReference : AnalyzerReference, IEquatable<AnalyzerReference>
{
private delegate IEnumerable<string> AttributeLanguagesFunc(PEModule module, CustomAttributeHandle attribute);
private delegate ImmutableArray<string> AttributeLanguagesFunc(PEModule module, CustomAttributeHandle attribute);

public override string FullPath { get; }

Expand Down Expand Up @@ -224,48 +224,63 @@ private static ImmutableSortedDictionary<string, ImmutableHashSet<string>> GetAn
{
using var assembly = AssemblyMetadata.CreateFromFile(fullPath);

// This is longer than strictly necessary to avoid thrashing the GC with string allocations
// in the call to GetFullyQualifiedTypeNames. Specifically, this checks for the presence of
// supported languages prior to creating the type names.
var typeNameMap = from module in assembly.GetModules()
from typeDefHandle in module.MetadataReader.TypeDefinitions
let typeDef = module.MetadataReader.GetTypeDefinition(typeDefHandle)
let supportedLanguages = GetSupportedLanguages(typeDef, module.Module, attributeType, languagesFunc)
where supportedLanguages.Any()
let typeName = GetFullyQualifiedTypeName(typeDef, module.Module)
from supportedLanguage in supportedLanguages
group typeName by supportedLanguage;

return typeNameMap.ToImmutableSortedDictionary(g => g.Key, g => g.ToImmutableHashSet(), StringComparer.OrdinalIgnoreCase);
Dictionary<string, ImmutableHashSet<string>.Builder> typeNameMap = new Dictionary<string, ImmutableHashSet<string>.Builder>(StringComparer.OrdinalIgnoreCase);
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@333fred 333fred Jul 17, 2024

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Should we use ImmutableSegmentedHashSet instead?

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@ToddGrun ToddGrun Jul 17, 2024

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I didn't see these hitting the LOH in the profile that I looked at, so I'd prefer to keep as-is, without that evidence to back up such a change.


foreach (var module in assembly.GetModules())
{
foreach (var typeDefHandle in module.MetadataReader.TypeDefinitions)
{
var typeDef = module.MetadataReader.GetTypeDefinition(typeDefHandle);
var supportedLanguages = GetSupportedLanguages(typeDef, module.Module, attributeType, languagesFunc);

// PERF: avoid calling GetFullyQualifiedTypeName when no supported languages.
if (supportedLanguages.Length > 0)
{
var typeName = GetFullyQualifiedTypeName(typeDef, module.Module);
foreach (var supportedLanguage in supportedLanguages)
{
if (!typeNameMap.TryGetValue(supportedLanguage, out var builder))
{
builder = ImmutableHashSet.CreateBuilder<string>();
typeNameMap.Add(supportedLanguage, builder);
}

builder.Add(typeName);
}
}
}
}

return typeNameMap.ToImmutableSortedDictionary(g => g.Key, g => g.Value.ToImmutable(), StringComparer.OrdinalIgnoreCase);
}

private static IEnumerable<string> GetSupportedLanguages(TypeDefinition typeDef, PEModule peModule, Type attributeType, AttributeLanguagesFunc languagesFunc)
private static ImmutableArray<string> GetSupportedLanguages(TypeDefinition typeDef, PEModule peModule, Type attributeType, AttributeLanguagesFunc languagesFunc)
{
IEnumerable<string>? result = null;
ImmutableArray<string> result = [];
foreach (CustomAttributeHandle customAttrHandle in typeDef.GetCustomAttributes())
{
if (peModule.IsTargetAttribute(customAttrHandle, attributeType.Namespace!, attributeType.Name, ctor: out _))
{
if (languagesFunc(peModule, customAttrHandle) is { } attributeSupportedLanguages)
{
if (result is null)
if (result.IsDefaultOrEmpty)
{
result = attributeSupportedLanguages;
}
else
{
// This is a slow path, but only occurs if a single type has multiple
// DiagnosticAnalyzerAttribute instances applied to it.
result = result.Concat(attributeSupportedLanguages);
result = result.AddRange(attributeSupportedLanguages);
}
}
}
}

return result ?? SpecializedCollections.EmptyEnumerable<string>();
return result;
}

private static IEnumerable<string> GetDiagnosticsAnalyzerSupportedLanguages(PEModule peModule, CustomAttributeHandle customAttrHandle)
private static ImmutableArray<string> GetDiagnosticsAnalyzerSupportedLanguages(PEModule peModule, CustomAttributeHandle customAttrHandle)
{
// The DiagnosticAnalyzerAttribute has one constructor, which has a string parameter for the
// first supported language and an array parameter for additional supported languages.
Expand All @@ -274,7 +289,7 @@ private static IEnumerable<string> GetDiagnosticsAnalyzerSupportedLanguages(PEMo
return ReadLanguagesFromAttribute(ref argsReader);
}

private static IEnumerable<string> GetGeneratorSupportedLanguages(PEModule peModule, CustomAttributeHandle customAttrHandle)
private static ImmutableArray<string> GetGeneratorSupportedLanguages(PEModule peModule, CustomAttributeHandle customAttrHandle)
{
// The GeneratorAttribute has two constructors: one default, and one with a string parameter for the
// first supported language and an array parameter for additional supported languages.
Expand All @@ -293,7 +308,7 @@ private static IEnumerable<string> GetGeneratorSupportedLanguages(PEModule peMod

// https://github.com/dotnet/roslyn/issues/53994 tracks re-enabling nullable and fixing this method
#nullable disable
private static IEnumerable<string> ReadLanguagesFromAttribute(ref BlobReader argsReader)
private static ImmutableArray<string> ReadLanguagesFromAttribute(ref BlobReader argsReader)
{
if (argsReader.Length > 4)
{
Expand All @@ -303,22 +318,22 @@ private static IEnumerable<string> ReadLanguagesFromAttribute(ref BlobReader arg
string firstLanguageName;
if (!PEModule.CrackStringInAttributeValue(out firstLanguageName, ref argsReader))
{
return SpecializedCollections.EmptyEnumerable<string>();
return [];
}

ImmutableArray<string> additionalLanguageNames;
if (PEModule.CrackStringArrayInAttributeValue(out additionalLanguageNames, ref argsReader))
{
if (additionalLanguageNames.Length == 0)
{
return SpecializedCollections.SingletonEnumerable(firstLanguageName);
return [firstLanguageName];
}

return additionalLanguageNames.Insert(0, firstLanguageName);
}
}
}
return SpecializedCollections.EmptyEnumerable<string>();
return [];
}

#nullable enable
Expand Down