[LibraryImportGenerator] Allow span copy for char arrays instead of m…

…anual copy loop (#69764)
dotnet · May 25, 2022 · 1601356 · 1601356
1 parent 7015fa2
commit 1601356
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Showing 2 changed files with 92 additions and 28 deletions.
diff --git a/...rosoft.Interop.SourceGeneration/Marshalling/AttributedMarshallingModelGeneratorFactory.cs b/...rosoft.Interop.SourceGeneration/Marshalling/AttributedMarshallingModelGeneratorFactory.cs
@@ -305,8 +305,6 @@ private IMarshallingGenerator CreateNativeCollectionMarshaller(
             IMarshallingGenerator elementMarshaller = _elementMarshallingGenerator.Create(
                 elementInfo,
                 new LinearCollectionElementMarshallingCodeContext(StubCodeContext.Stage.Setup, string.Empty, string.Empty, context));
-            TypeSyntax elementType = elementMarshaller.AsNativeType(elementInfo);
-
 
             ExpressionSyntax numElementsExpression = LiteralExpression(SyntaxKind.NumericLiteralExpression, Literal(0));
             if (info.IsManagedReturnPosition || (info.IsByRef && info.RefKind != RefKind.In))
@@ -315,9 +313,9 @@ private IMarshallingGenerator CreateNativeCollectionMarshaller(
                 numElementsExpression = GetNumElementsExpressionFromMarshallingInfo(info, collectionInfo.ElementCountInfo, context);
             }
 
-            bool isBlittable = elementMarshaller is BlittableMarshaller;
-
-            if (isBlittable)
+            bool enableArrayPinning = elementMarshaller is BlittableMarshaller;
+            bool treatAsBlittable = enableArrayPinning || elementMarshaller is Utf16CharMarshaller;
+            if (treatAsBlittable)
             {
                 marshallingStrategy = new LinearCollectionWithBlittableElementsMarshalling(marshallingStrategy, collectionInfo.ElementType.Syntax, numElementsExpression);
             }
@@ -332,16 +330,17 @@ private IMarshallingGenerator CreateNativeCollectionMarshaller(
                 marshallingStrategy = DecorateWithTwoStageMarshallingStrategy(collectionInfo, marshallingStrategy);
             }
 
+            TypeSyntax nativeElementType = elementMarshaller.AsNativeType(elementInfo);
             marshallingStrategy = new SizeOfElementMarshalling(
                 marshallingStrategy,
-                SizeOfExpression(elementType));
+                SizeOfExpression(nativeElementType));
 
             if (collectionInfo.UseDefaultMarshalling && info.ManagedType is SzArrayType)
             {
                 return new ArrayMarshaller(
                     new CustomNativeTypeMarshallingGenerator(marshallingStrategy, enableByValueContentsMarshalling: true),
-                    elementType,
-                    isBlittable);
+                    collectionInfo.ElementType.Syntax,
+                    enableArrayPinning);
             }
 
             IMarshallingGenerator marshallingGenerator = new CustomNativeTypeMarshallingGenerator(marshallingStrategy, enableByValueContentsMarshalling: false);

diff --git a/...en/Microsoft.Interop.SourceGeneration/Marshalling/ICustomNativeTypeMarshallingStrategy.cs b/...en/Microsoft.Interop.SourceGeneration/Marshalling/ICustomNativeTypeMarshallingStrategy.cs
@@ -687,6 +687,19 @@ public IEnumerable<StatementSyntax> GenerateMarshalStatements(TypePositionInfo i
             if (!info.IsByRef && info.ByValueContentsMarshalKind == ByValueContentsMarshalKind.Out)
             {
                 // If the parameter is marshalled by-value [Out], then we don't marshal the contents of the collection.
+                // We do clear the span, so that if the invoke target doesn't fill it, we aren't left with undefined content.
+                // <nativeIdentifier>.GetNativeValuesDestination().Clear();
+                yield return ExpressionStatement(
+                    InvocationExpression(
+                        MemberAccessExpression(
+                            SyntaxKind.SimpleMemberAccessExpression,
+                            InvocationExpression(
+                                MemberAccessExpression(
+                                    SyntaxKind.SimpleMemberAccessExpression,
+                                    IdentifierName(nativeIdentifier),
+                                    IdentifierName(ShapeMemberNames.LinearCollection.GetNativeValuesDestination)),
+                                ArgumentList()),
+                            IdentifierName("Clear"))));
                 yield break;
             }
 
@@ -742,12 +755,76 @@ public IEnumerable<StatementSyntax> GenerateUnmarshalStatements(TypePositionInfo
         {
             string nativeIdentifier = context.GetIdentifiers(info).native;
             string numElementsIdentifier = context.GetAdditionalIdentifier(info, "numElements");
-            yield return LocalDeclarationStatement(
-                VariableDeclaration(
-                    PredefinedType(Token(SyntaxKind.IntKeyword)),
-                    SingletonSeparatedList(
-                        VariableDeclarator(numElementsIdentifier).WithInitializer(EqualsValueClause(_numElementsExpression)))));
-            // MemoryMarshal.Cast<byte, <elementType>>(<nativeIdentifier>.GetNativeValuesSource(<numElements>)).CopyTo(<nativeIdentifier>.GetManagedValuesDestination(<numElements>));
+
+            ExpressionSyntax copySource;
+            ExpressionSyntax copyDestination;
+            if (!info.IsByRef && info.ByValueContentsMarshalKind.HasFlag(ByValueContentsMarshalKind.Out))
+            {
+                // <nativeIdentifier>.GetNativeValuesDestination()
+                copySource = InvocationExpression(
+                    MemberAccessExpression(
+                        SyntaxKind.SimpleMemberAccessExpression,
+                        IdentifierName(nativeIdentifier),
+                        IdentifierName(ShapeMemberNames.LinearCollection.GetNativeValuesDestination)));
+
+                // MemoryMarshal.CreateSpan(ref MemoryMarshal.GetReference(<nativeIdentifier>.GetManagedValuesSource()), <nativeIdentifier>.GetManagedValuesSource().Length)
+                copyDestination = InvocationExpression(
+                    MemberAccessExpression(
+                        SyntaxKind.SimpleMemberAccessExpression,
+                        ParseName(TypeNames.System_Runtime_InteropServices_MemoryMarshal),
+                        IdentifierName("CreateSpan")),
+                    ArgumentList(
+                        SeparatedList(new[]
+                        {
+                            Argument(
+                                InvocationExpression(
+                                    MemberAccessExpression(SyntaxKind.SimpleMemberAccessExpression,
+                                        ParseName(TypeNames.System_Runtime_InteropServices_MemoryMarshal),
+                                        IdentifierName("GetReference")),
+                                    ArgumentList(SingletonSeparatedList(
+                                        Argument(
+                                            InvocationExpression(
+                                                MemberAccessExpression(SyntaxKind.SimpleMemberAccessExpression,
+                                                    IdentifierName(nativeIdentifier),
+                                                    IdentifierName(ShapeMemberNames.LinearCollection.GetManagedValuesSource))))))))
+                                .WithRefKindKeyword(
+                                    Token(SyntaxKind.RefKeyword)),
+                            Argument(
+                                MemberAccessExpression(SyntaxKind.SimpleMemberAccessExpression,
+                                    InvocationExpression(
+                                        MemberAccessExpression(SyntaxKind.SimpleMemberAccessExpression,
+                                            IdentifierName(nativeIdentifier),
+                                            IdentifierName(ShapeMemberNames.LinearCollection.GetManagedValuesSource))),
+                                    IdentifierName("Length")))
+                        })));
+
+            }
+            else
+            {
+                yield return LocalDeclarationStatement(
+                    VariableDeclaration(
+                        PredefinedType(Token(SyntaxKind.IntKeyword)),
+                        SingletonSeparatedList(
+                            VariableDeclarator(numElementsIdentifier).WithInitializer(EqualsValueClause(_numElementsExpression)))));
+
+                // <nativeIdentifier>.GetNativeValuesSource(<numElements>)
+                copySource = InvocationExpression(
+                    MemberAccessExpression(
+                        SyntaxKind.SimpleMemberAccessExpression,
+                        IdentifierName(nativeIdentifier),
+                        IdentifierName(ShapeMemberNames.LinearCollection.GetNativeValuesSource)),
+                    ArgumentList(SingletonSeparatedList(Argument(IdentifierName(numElementsIdentifier)))));
+
+                // <nativeIdentifier>.GetManagedValuesDestination(<numElements>)
+                copyDestination = InvocationExpression(
+                    MemberAccessExpression(
+                        SyntaxKind.SimpleMemberAccessExpression,
+                        IdentifierName(nativeIdentifier),
+                        IdentifierName(ShapeMemberNames.LinearCollection.GetManagedValuesDestination)),
+                    ArgumentList(SingletonSeparatedList(Argument(IdentifierName(numElementsIdentifier)))));
+            }
+
+            // MemoryMarshal.Cast<byte, <elementType>>(<copySource>).CopyTo(<copyDestination>);
             yield return ExpressionStatement(
                 InvocationExpression(
                     MemberAccessExpression(
@@ -767,22 +844,10 @@ public IEnumerable<StatementSyntax> GenerateUnmarshalStatements(TypePositionInfo
                                                     _elementType
                                                 })))))
                             .AddArgumentListArguments(
-                                Argument(
-                                    InvocationExpression(
-                                        MemberAccessExpression(
-                                            SyntaxKind.SimpleMemberAccessExpression,
-                                            IdentifierName(nativeIdentifier),
-                                            IdentifierName(ShapeMemberNames.LinearCollection.GetNativeValuesSource)),
-                                        ArgumentList(SingletonSeparatedList(Argument(IdentifierName(numElementsIdentifier))))))),
+                                Argument(copySource)),
                         IdentifierName("CopyTo")))
                 .AddArgumentListArguments(
-                    Argument(
-                        InvocationExpression(
-                                        MemberAccessExpression(
-                                            SyntaxKind.SimpleMemberAccessExpression,
-                                            IdentifierName(nativeIdentifier),
-                                            IdentifierName(ShapeMemberNames.LinearCollection.GetManagedValuesDestination)),
-                                        ArgumentList(SingletonSeparatedList(Argument(IdentifierName(numElementsIdentifier))))))));
+                    Argument(copyDestination)));
 
             foreach (StatementSyntax statement in _innerMarshaller.GenerateUnmarshalStatements(info, context))
             {