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Merged
jevansaks merged 3 commits into from
Jan 22, 2026
Merged

Reduce allocations #1620

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225a041
Reduce allocations when constructing syntax nodes
DoctorKrolic Jan 16, 2026
7fff9ac
Qualify `Marshal` name
DoctorKrolic Jan 16, 2026
07a6e58
Revert collection expression usage to avoid style warning
DoctorKrolic Jan 17, 2026
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2 changes: 1 addition & 1 deletion src/Microsoft.Windows.CsWin32/ArrayTypeHandleInfo.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -20,7 +20,7 @@ internal override TypeSyntaxAndMarshaling ToTypeSyntax(TypeSyntaxSettings inputs
TypeSyntaxAndMarshaling element = this.ElementType.ToTypeSyntax(inputs, forElement, customAttributes);
if (inputs.AllowMarshaling || inputs.IsField)
{
ArrayTypeSyntax arrayType = ArrayType(element.Type, SingletonList(ArrayRankSpecifier().AddSizes(this.Shape.Sizes.Select(size => LiteralExpression(SyntaxKind.NumericLiteralExpression, Literal(size))).ToArray<ExpressionSyntax>())));
ArrayTypeSyntax arrayType = ArrayType(element.Type, [ArrayRankSpecifier([.. this.Shape.Sizes.Select(size => LiteralExpression(SyntaxKind.NumericLiteralExpression, Literal(size)))])]);
MarshalAsAttribute? marshalAs = element.MarshalAsAttribute is object ? new MarshalAsAttribute(UnmanagedType.LPArray) { ArraySubType = element.MarshalAsAttribute.Value } : null;
return new TypeSyntaxAndMarshaling(arrayType, marshalAs, element.NativeArrayInfo);
}
Expand Down
110 changes: 39 additions & 71 deletions src/Microsoft.Windows.CsWin32/FastSyntaxFactory.cs
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291 changes: 137 additions & 154 deletions src/Microsoft.Windows.CsWin32/Generator.Com.cs
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20 changes: 8 additions & 12 deletions src/Microsoft.Windows.CsWin32/Generator.Constant.cs
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Expand Up @@ -227,7 +227,7 @@ ReadOnlyMemory<char> TrimCurlyBraces(ReadOnlyMemory<char> arg)
i++;
}

return ObjectCreationExpression(targetType).AddArgumentListArguments(argExpressions);
return ObjectCreationExpression(targetType, [.. argExpressions]);
}
}

Expand Down Expand Up @@ -259,7 +259,7 @@ ReadOnlyMemory<char> TrimCurlyBraces(ReadOnlyMemory<char> arg)

return ObjectCreationExpression(targetType)
.WithArgumentList(null)
.WithInitializer(InitializerExpression(SyntaxKind.ObjectInitializerExpression, SeparatedList<ExpressionSyntax>()).AddExpressions(fieldAssignmentExpressions));
.WithInitializer(InitializerExpression(SyntaxKind.ObjectInitializerExpression).AddExpressions(fieldAssignmentExpressions));
}

private ExpressionSyntax CreateConstant(ReadOnlyMemory<char> argsAsString, TypeHandleInfo targetType, out bool unsafeRequired)
Expand Down Expand Up @@ -312,8 +312,7 @@ private ExpressionSyntax CreateByteArrayConstant(ReadOnlyMemory<char> argsAsStri
TypeSyntax byteTypeSyntax = PredefinedType(Token(SyntaxKind.ByteKeyword));
return CastExpression(
MakeReadOnlySpanOfT(byteTypeSyntax),
ArrayCreationExpression(ArrayType(byteTypeSyntax).AddRankSpecifiers(ArrayRankSpecifier())).WithInitializer(InitializerExpression(SyntaxKind.ArrayInitializerExpression, SeparatedList<ExpressionSyntax>())
.AddExpressions(args.Select(b => ToExpressionSyntax(PrimitiveTypeCode.Byte, b)).ToArray())));
ArrayCreationExpression(ArrayType(byteTypeSyntax, [ArrayRankSpecifier()]), InitializerExpression(SyntaxKind.ArrayInitializerExpression, [.. args.Select(b => ToExpressionSyntax(PrimitiveTypeCode.Byte, b))])));
}

private ExpressionSyntax CreateGuidConstant(List<ReadOnlyMemory<char>> guidArgs)
Expand All @@ -338,7 +337,7 @@ private ExpressionSyntax CreateGuidConstant(List<ReadOnlyMemory<char>> guidArgs)
Literal(byte.Parse(guidArgs[10].ToString(), CultureInfo.InvariantCulture)),
};

return ObjectCreationExpression(GuidTypeSyntax).AddArgumentListArguments(ctorArgs.Select(t => Argument(LiteralExpression(SyntaxKind.NumericLiteralExpression, t))).ToArray());
return ObjectCreationExpression(GuidTypeSyntax, [.. ctorArgs.Select(t => Argument(LiteralExpression(SyntaxKind.NumericLiteralExpression, t)))]);
}

private ExpressionSyntax CreateConstant(CustomAttribute constantAttribute, TypeHandleInfo targetType, out bool unsafeRequired)
Expand Down Expand Up @@ -389,7 +388,7 @@ private FieldDeclarationSyntax DeclareConstant(FieldDefinition fieldDef)
}
}

SyntaxTokenList modifiers = TokenList(TokenWithSpace(this.Visibility));
SyntaxTokenList modifiers = [TokenWithSpace(this.Visibility)];
if (this.IsTypeDefStruct(fieldTypeInfo) || value is ObjectCreationExpressionSyntax)
{
modifiers = modifiers.Add(TokenWithSpace(SyntaxKind.StaticKeyword)).Add(TokenWithSpace(SyntaxKind.ReadOnlyKeyword));
Expand All @@ -404,9 +403,7 @@ private FieldDeclarationSyntax DeclareConstant(FieldDefinition fieldDef)
modifiers = modifiers.Add(TokenWithSpace(SyntaxKind.UnsafeKeyword));
}

FieldDeclarationSyntax? result = FieldDeclaration(VariableDeclaration(fieldType.Type).AddVariables(
VariableDeclarator(Identifier(name)).WithInitializer(EqualsValueClause(value))))
.WithModifiers(modifiers);
FieldDeclarationSyntax? result = FieldDeclaration(modifiers, VariableDeclaration(fieldType.Type, [VariableDeclarator(Identifier(name), EqualsValueClause(value))]));
result = fieldType.AddMarshalAs(result);
result = this.AddApiDocumentation(result.Declaration.Variables[0].Identifier.ValueText, result);

Expand All @@ -423,8 +420,7 @@ private FieldDeclarationSyntax DeclareConstant(FieldDefinition fieldDef)

private ClassDeclarationSyntax DeclareConstantDefiningClass()
{
return ClassDeclaration(this.methodsAndConstantsClassName.Identifier)
.AddMembers(this.committedCode.TopLevelFields.ToArray())
.WithModifiers(TokenList(TokenWithSpace(this.Visibility), TokenWithSpace(SyntaxKind.StaticKeyword), TokenWithSpace(SyntaxKind.PartialKeyword)));
return ClassDeclaration(this.methodsAndConstantsClassName.Identifier, [.. this.committedCode.TopLevelFields])
.WithModifiers([TokenWithSpace(this.Visibility), TokenWithSpace(SyntaxKind.StaticKeyword), TokenWithSpace(SyntaxKind.PartialKeyword)]);
}
}
61 changes: 26 additions & 35 deletions src/Microsoft.Windows.CsWin32/Generator.CustomMarshaller.cs
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Expand Up @@ -67,9 +67,8 @@ internal string RequestCustomEnumMarshaller(string qualifiedEnumTypeName, Unmana
// }
MethodDeclarationSyntax convertToManagedMethod = MethodDeclaration(enumTypeSyntax, Identifier("ConvertToManaged"))
.AddModifiers(TokenWithSpace(SyntaxKind.PublicKeyword), TokenWithSpace(SyntaxKind.StaticKeyword), TokenWithSpace(SyntaxKind.UnsafeKeyword))
.AddParameterListParameters(Parameter(Identifier("unmanaged")).WithType(unmanagedTypeSyntax.WithTrailingTrivia(Space)))
.WithBody(Block().AddStatements(
ReturnStatement(UncheckedExpression(CastExpression(enumTypeSyntax, IdentifierName("unmanaged"))))));
.AddParameterListParameters(Parameter(unmanagedTypeSyntax.WithTrailingTrivia(Space), Identifier("unmanaged")))
.WithBody(Block(ReturnStatement(UncheckedExpression(CastExpression(enumTypeSyntax, IdentifierName("unmanaged"))))));

// Create ConvertToUnmanaged method
// public static uint ConvertToUnmanaged(Enum managed)
Expand All @@ -78,24 +77,22 @@ internal string RequestCustomEnumMarshaller(string qualifiedEnumTypeName, Unmana
// }
MethodDeclarationSyntax convertToUnmanagedMethod = MethodDeclaration(unmanagedTypeSyntax, Identifier("ConvertToUnmanaged"))
.AddModifiers(TokenWithSpace(SyntaxKind.PublicKeyword), TokenWithSpace(SyntaxKind.StaticKeyword))
.AddParameterListParameters(Parameter(Identifier("managed")).WithType(enumTypeSyntax.WithTrailingTrivia(Space)))
.WithBody(Block().AddStatements(
ReturnStatement(UncheckedExpression(CastExpression(unmanagedTypeSyntax, IdentifierName("managed"))))));
.AddParameterListParameters(Parameter(enumTypeSyntax.WithTrailingTrivia(Space), Identifier("managed")))
.WithBody(Block(ReturnStatement(UncheckedExpression(CastExpression(unmanagedTypeSyntax, IdentifierName("managed"))))));

// Create Free method
// public static void Free(uint unmanaged)
// {
// }
MethodDeclarationSyntax freeMethod = MethodDeclaration(PredefinedType(Token(SyntaxKind.VoidKeyword)), Identifier("Free"))
.AddModifiers(TokenWithSpace(SyntaxKind.PublicKeyword), TokenWithSpace(SyntaxKind.StaticKeyword))
.AddParameterListParameters(Parameter(Identifier("unmanaged")).WithType(unmanagedTypeSyntax.WithTrailingTrivia(Space)))
.AddParameterListParameters(Parameter(unmanagedTypeSyntax.WithTrailingTrivia(Space), Identifier("unmanaged")))
.WithBody(Block()); // Empty body

// Create the class declaration
ClassDeclarationSyntax marshallerClass = ClassDeclaration(Identifier(customTypeMarshallerName))
ClassDeclarationSyntax marshallerClass = ClassDeclaration(Identifier(customTypeMarshallerName), [convertToManagedMethod, convertToUnmanagedMethod, freeMethod])
.AddModifiers(TokenWithSpace(this.Visibility), TokenWithSpace(SyntaxKind.StaticKeyword))
.AddAttributeLists(customMarshallerAttributes.Select(attr => AttributeList().AddAttributes(attr)).ToArray())
.AddMembers(convertToManagedMethod, convertToUnmanagedMethod, freeMethod);
.AddAttributeLists(customMarshallerAttributes.Select(attr => AttributeList(attr)).ToArray());

marshallerClass = marshallerClass.WithAdditionalAnnotations(new SyntaxAnnotation(NamespaceContainerAnnotation, shortNamespace));

Expand Down Expand Up @@ -140,20 +137,18 @@ internal string RequestCustomTypeDefMarshaller(string fullyQualifiedTypeName, Ty
// public static unsafe void* ConvertToUnmanaged(HWND managed) => managed.Value;
MethodDeclarationSyntax toUnmanaged = MethodDeclaration(unmanagedTypeSyntax, Identifier("ConvertToUnmanaged"))
.AddModifiers(TokenWithSpace(SyntaxKind.PublicKeyword), TokenWithSpace(SyntaxKind.StaticKeyword), TokenWithSpace(SyntaxKind.UnsafeKeyword))
.AddParameterListParameters(Parameter(Identifier("managed")).WithType(typedefTypeSyntax.WithTrailingTrivia(Space)))
.AddParameterListParameters(Parameter(typedefTypeSyntax.WithTrailingTrivia(Space), Identifier("managed")))
.WithBody(Block(ReturnStatement(MemberAccessExpression(SyntaxKind.SimpleMemberAccessExpression, IdentifierName("managed"), IdentifierName("Value")))));

// public static unsafe HWND ConvertToManaged(void* unmanaged) => new(unmanaged);
MethodDeclarationSyntax toManaged = MethodDeclaration(typedefTypeSyntax, Identifier("ConvertToManaged"))
.AddModifiers(TokenWithSpace(SyntaxKind.PublicKeyword), TokenWithSpace(SyntaxKind.StaticKeyword), TokenWithSpace(SyntaxKind.UnsafeKeyword))
.AddParameterListParameters(Parameter(Identifier("unmanaged")).WithType(unmanagedTypeSyntax.WithTrailingTrivia(Space)))
.WithBody(Block(ReturnStatement(ObjectCreationExpression(typedefTypeSyntax)
.WithArgumentList(ArgumentList(SingletonSeparatedList(Argument(IdentifierName("unmanaged"))))))));
.AddParameterListParameters(Parameter(unmanagedTypeSyntax.WithTrailingTrivia(Space), Identifier("unmanaged")))
.WithBody(Block(ReturnStatement(ObjectCreationExpression(typedefTypeSyntax, [Argument(IdentifierName("unmanaged"))]))));

ClassDeclarationSyntax marshallerClass = ClassDeclaration(Identifier(customTypeMarshallerName))
ClassDeclarationSyntax marshallerClass = ClassDeclaration(Identifier(customTypeMarshallerName), [toUnmanaged, toManaged])
.AddModifiers(TokenWithSpace(this.Visibility), TokenWithSpace(SyntaxKind.StaticKeyword))
.AddAttributeLists(AttributeList().AddAttributes(attribute))
.AddMembers(toUnmanaged, toManaged)
.AddAttributeLists(AttributeList(attribute))
.WithAdditionalAnnotations(new SyntaxAnnotation(NamespaceContainerAnnotation, shortNamespace));

string qualifiedName = $"global::{this.Namespace}.{shortNamespace}.{customTypeMarshallerName}";
Expand Down Expand Up @@ -215,15 +210,14 @@ internal string RequestCustomWinRTMarshaller(string qualifiedWinRTTypeName)
// }
MethodDeclarationSyntax convertToManagedMethod = MethodDeclaration(winrtTypeSyntax, Identifier("ConvertToManaged"))
.AddModifiers(TokenWithSpace(SyntaxKind.PublicKeyword), TokenWithSpace(SyntaxKind.StaticKeyword), TokenWithSpace(SyntaxKind.UnsafeKeyword))
.AddParameterListParameters(Parameter(Identifier("unmanaged")).WithType(unmanagedTypeSyntax.WithTrailingTrivia(Space)))
.WithBody(Block().AddStatements(
.AddParameterListParameters(Parameter(unmanagedTypeSyntax.WithTrailingTrivia(Space), Identifier("unmanaged")))
.WithBody(Block(
ReturnStatement(InvocationExpression(
MemberAccessExpression(
SyntaxKind.SimpleMemberAccessExpression,
GenericName("global::WinRT.MarshalInterface")
.AddTypeArgumentListArguments(winrtTypeSyntax),
GenericName("global::WinRT.MarshalInterface", [winrtTypeSyntax]),
IdentifierName("FromAbi")),
ArgumentList().AddArguments(Argument(IdentifierName("unmanaged")))))));
[Argument(IdentifierName("unmanaged"))]))));

// Create ConvertToUnmanaged method
// public static nint ConvertToUnmanaged(T managed)
Expand All @@ -232,15 +226,14 @@ internal string RequestCustomWinRTMarshaller(string qualifiedWinRTTypeName)
// }
MethodDeclarationSyntax convertToUnmanagedMethod = MethodDeclaration(unmanagedTypeSyntax, Identifier("ConvertToUnmanaged"))
.AddModifiers(TokenWithSpace(SyntaxKind.PublicKeyword), TokenWithSpace(SyntaxKind.StaticKeyword))
.AddParameterListParameters(Parameter(Identifier("managed")).WithType(winrtTypeSyntax.WithTrailingTrivia(Space)))
.WithBody(Block().AddStatements(
.AddParameterListParameters(Parameter(winrtTypeSyntax.WithTrailingTrivia(Space), Identifier("managed")))
.WithBody(Block(
ReturnStatement(InvocationExpression(
MemberAccessExpression(
SyntaxKind.SimpleMemberAccessExpression,
GenericName("global::WinRT.MarshalInterface")
.AddTypeArgumentListArguments(winrtTypeSyntax),
GenericName("global::WinRT.MarshalInterface", [winrtTypeSyntax]),
IdentifierName("FromManaged")),
ArgumentList().AddArguments(Argument(IdentifierName("managed")))))));
[Argument(IdentifierName("managed"))]))));

// Create Free method
// public static void Free(nint unmanaged)
Expand All @@ -249,21 +242,19 @@ internal string RequestCustomWinRTMarshaller(string qualifiedWinRTTypeName)
// }
MethodDeclarationSyntax freeMethod = MethodDeclaration(PredefinedType(Token(SyntaxKind.VoidKeyword)), Identifier("Free"))
.AddModifiers(TokenWithSpace(SyntaxKind.PublicKeyword), TokenWithSpace(SyntaxKind.StaticKeyword))
.AddParameterListParameters(Parameter(Identifier("unmanaged")).WithType(unmanagedTypeSyntax.WithTrailingTrivia(Space)))
.WithBody(Block().AddStatements(
.AddParameterListParameters(Parameter(unmanagedTypeSyntax.WithTrailingTrivia(Space), Identifier("unmanaged")))
.WithBody(Block(
ExpressionStatement(InvocationExpression(
MemberAccessExpression(
SyntaxKind.SimpleMemberAccessExpression,
GenericName("global::WinRT.MarshalInterface")
.AddTypeArgumentListArguments(winrtTypeSyntax),
GenericName("global::WinRT.MarshalInterface", [winrtTypeSyntax]),
IdentifierName("DisposeAbi")),
ArgumentList().AddArguments(Argument(IdentifierName("unmanaged")))))));
[Argument(IdentifierName("unmanaged"))]))));

// Create the class declaration
ClassDeclarationSyntax marshallerClass = ClassDeclaration(Identifier(customTypeMarshallerName))
ClassDeclarationSyntax marshallerClass = ClassDeclaration(Identifier(customTypeMarshallerName), [convertToManagedMethod, convertToUnmanagedMethod, freeMethod])
.AddModifiers(TokenWithSpace(this.Visibility), TokenWithSpace(SyntaxKind.StaticKeyword))
.AddAttributeLists(customMarshallerAttributes.Select(attr => AttributeList().AddAttributes(attr)).ToArray())
.AddMembers(convertToManagedMethod, convertToUnmanagedMethod, freeMethod);
.AddAttributeLists(customMarshallerAttributes.Select(attr => AttributeList(attr)).ToArray());

marshallerClass = marshallerClass.WithAdditionalAnnotations(new SyntaxAnnotation(NamespaceContainerAnnotation, marshallerNamespace));

Expand Down
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