Merge pull request #40786 from jasonmalinowski/improve-getdeclaredsymbols-perf

Speed up ISemanticFactsService.GetDeclaredSymbol

src/Workspaces/CSharp/Portable/LanguageServices/CSharpSemanticFactsService.cs

@@ -145,12 +145,30 @@ public string GenerateNameForExpression(SemanticModel semanticModel, SyntaxNode
         public ISymbol GetDeclaredSymbol(SemanticModel semanticModel, SyntaxToken token, CancellationToken cancellationToken)
         {
             var location = token.GetLocation();
-            var q = from node in token.GetAncestors<SyntaxNode>()
-                    let symbol = semanticModel.GetDeclaredSymbol(node, cancellationToken)
-                    where symbol != null && symbol.Locations.Contains(location)
-                    select symbol;
 
-            return q.FirstOrDefault();
+            foreach (var ancestor in token.GetAncestors<SyntaxNode>())
+            {
+                var symbol = semanticModel.GetDeclaredSymbol(ancestor, cancellationToken);
+
+                if (symbol != null)
+                {
+                    if (symbol.Locations.Contains(location))
+                    {
+                        return symbol;
+                    }
+
+                    // We found some symbol, but it defined something else. We're not going to have a higher node defining _another_ symbol with this token, so we can stop now.
+                    return null;
+                }
+
+                // If we hit an executable statement syntax and didn't find anything yet, we can just stop now -- anything higher would be a member declaration which won't be defined by something inside a statement.
+                if (SyntaxFactsService.IsExecutableStatement(ancestor))
+                {
+                    return null;
+                }
+            }
+
+            return null;
         }
 
         public bool LastEnumValueHasInitializer(INamedTypeSymbol namedTypeSymbol)

src/Workspaces/VisualBasic/Portable/LanguageServices/VisualBasicSemanticFactsService.vb

@@ -145,16 +145,31 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
         Public Function GetDeclaredSymbol(semanticModel As SemanticModel, token As SyntaxToken, cancellationToken As CancellationToken) As ISymbol Implements ISemanticFactsService.GetDeclaredSymbol
             Dim location = token.GetLocation()
 
-            Dim q = From node In token.GetAncestors(Of SyntaxNode)()
-                    Where Not TypeOf node Is AggregationRangeVariableSyntax AndAlso
-                          Not TypeOf node Is CollectionRangeVariableSyntax AndAlso
-                          Not TypeOf node Is ExpressionRangeVariableSyntax AndAlso
-                          Not TypeOf node Is InferredFieldInitializerSyntax
-                    Let symbol = semanticModel.GetDeclaredSymbol(node, cancellationToken)
-                    Where symbol IsNot Nothing AndAlso symbol.Locations.Contains(location)
-                    Select symbol
-
-            Return q.FirstOrDefault()
+            For Each ancestor In token.GetAncestors(Of SyntaxNode)()
+                If Not TypeOf ancestor Is AggregationRangeVariableSyntax AndAlso
+                   Not TypeOf ancestor Is CollectionRangeVariableSyntax AndAlso
+                   Not TypeOf ancestor Is ExpressionRangeVariableSyntax AndAlso
+                   Not TypeOf ancestor Is InferredFieldInitializerSyntax Then
+
+                    Dim symbol = semanticModel.GetDeclaredSymbol(ancestor)
+
+                    If symbol IsNot Nothing Then
+                        If symbol.Locations.Contains(location) Then
+                            Return symbol
+                        End If
+
+                        ' We found some symbol, but it defined something else. We're not going to have a higher node defining _another_ symbol with this token, so we can stop now.
+                        Return Nothing
+                    End If
+
+                    ' If we hit an executable statement syntax and didn't find anything yet, we can just stop now -- anything higher would be a member declaration which won't be defined by something inside a statement.
+                    If SyntaxFactsService.IsExecutableStatement(ancestor) Then
+                        Return Nothing
+                    End If
+                End If
+            Next
+
+            Return Nothing
         End Function
 
         Public Function LastEnumValueHasInitializer(namedTypeSymbol As INamedTypeSymbol) As Boolean Implements ISemanticFactsService.LastEnumValueHasInitializer