Remove caching of declaring syntax references for symbols in analyzer driver -...

Remove caching of declaring syntax references for symbols in analyzer driver - this was done as part of addressing some performance regressions, but the subsequent tuning should make the original change redundant.

Fixes #7156

src/Compilers/CSharp/Portable/Symbols/Source/SourceMemberContainerSymbol.cs

@@ -814,23 +814,10 @@ public override ImmutableArray<SyntaxReference> DeclaringSyntaxReferences
         {
             get
             {
-                // PERF: Declaring references are cached for compilations with event queue.
-                return this.DeclaringCompilation?.EventQueue != null ? GetCachedDeclaringReferences() : this.SyntaxReferences;
+                return SyntaxReferences;
             }
         }
 
-        private ImmutableArray<SyntaxReference> GetCachedDeclaringReferences()
-        {
-            ImmutableArray<SyntaxReference> declaringReferences;
-            if (!Diagnostics.AnalyzerDriver.TryGetCachedDeclaringReferences(this, this.DeclaringCompilation, out declaringReferences))
-            {
-                declaringReferences = this.SyntaxReferences;
-                Diagnostics.AnalyzerDriver.CacheDeclaringReferences(this, this.DeclaringCompilation, declaringReferences);
-            }
-
-            return declaringReferences;
-        }
-
         #endregion
 
         #region Members

src/Compilers/CSharp/Portable/Symbols/Source/SourceNamespaceSymbol.cs

@@ -111,23 +111,10 @@ public override ImmutableArray<SyntaxReference> DeclaringSyntaxReferences
         {
             get
             {
-                // PERF: Declaring references are cached for compilations with event queue.
-                return this.DeclaringCompilation?.EventQueue != null ? GetCachedDeclaringReferences() : ComputeDeclaringReferencesCore();
+                return ComputeDeclaringReferencesCore();
             }
         }
 
-        private ImmutableArray<SyntaxReference> GetCachedDeclaringReferences()
-        {
-            ImmutableArray<SyntaxReference> declaringReferences;
-            if (!Diagnostics.AnalyzerDriver.TryGetCachedDeclaringReferences(this, this.DeclaringCompilation, out declaringReferences))
-            {
-                declaringReferences = ComputeDeclaringReferencesCore();
-                Diagnostics.AnalyzerDriver.CacheDeclaringReferences(this, this.DeclaringCompilation, declaringReferences);
-            }
-
-            return declaringReferences;
-        }
-
         private ImmutableArray<SyntaxReference> ComputeDeclaringReferencesCore()
         {
             // SyntaxReference in the namespace declaration points to the name node of the namespace decl node not

src/Compilers/Core/Portable/DiagnosticAnalyzer/AnalysisState.cs

@@ -321,11 +321,6 @@ public async Task OnCompilationEventProcessedAsync(CompilationEvent compilationE
             {
                 UpdateEventsMap_NoLock(compilationEvent, add: false);
             }
-
-            if (symbolDeclaredEvent != null)
-            {
-                AnalyzerDriver.RemoveCachedDeclaringReferences(symbolDeclaredEvent.Symbol, symbolDeclaredEvent.Compilation);
-            }
         }
 
         /// <summary>

src/Compilers/Core/Portable/DiagnosticAnalyzer/AnalyzerDriver.CompilationData.cs

@@ -20,16 +20,9 @@ internal class CompilationData
             /// </summary>
             private readonly Dictionary<SyntaxTree, SemanticModel> _semanticModelsMap;
 
-            /// <summary>
-            /// Cached syntax references for a symbol for the lifetime of symbol declared event.
-            /// PERF: This cache reduces allocations for computing declaring syntax references for a symbol.
-            /// </summary>
-            private readonly Dictionary<ISymbol, ImmutableArray<SyntaxReference>> _symbolDeclarationsMap;
-
             public CompilationData(Compilation comp)
             {
                 _semanticModelsMap = new Dictionary<SyntaxTree, SemanticModel>();
-                _symbolDeclarationsMap = new Dictionary<ISymbol, ImmutableArray<SyntaxReference>>();
                 this.SuppressMessageAttributeState = new SuppressMessageAttributeState(comp);
                 this.DeclarationAnalysisDataMap = new Dictionary<SyntaxReference, DeclarationAnalysisData>();
             }
@@ -47,8 +40,7 @@ public SemanticModel GetOrCreateCachedSemanticModel(SyntaxTree tree, Compilation
                         return model;
                     }
                 }
-
-
+                
                 model = compilation.GetSemanticModel(tree);
 
                 // Invoke GetDiagnostics to populate the compilation's CompilationEvent queue.
@@ -69,36 +61,6 @@ public bool RemoveCachedSemanticModel(SyntaxTree tree)
                     return _semanticModelsMap.Remove(tree);
                 }
             }
-
-            public bool TryGetCachedDeclaringReferences(ISymbol symbol, out ImmutableArray<SyntaxReference> declaringReferences)
-            {
-                lock (_symbolDeclarationsMap)
-                {
-                    if (!_symbolDeclarationsMap.TryGetValue(symbol, out declaringReferences))
-                    {
-                        declaringReferences = default(ImmutableArray<SyntaxReference>);
-                        return false;
-                    }
-
-                    return true;
-                }
-            }
-
-            public void CacheDeclaringReferences(ISymbol symbol, ImmutableArray<SyntaxReference> declaringReferences)
-            {
-                lock (_symbolDeclarationsMap)
-                {
-                    _symbolDeclarationsMap[symbol] = declaringReferences;
-                }
-            }
-
-            public bool RemoveCachedDeclaringReferences(ISymbol symbol)
-            {
-                lock (_symbolDeclarationsMap)
-                {
-                    return _symbolDeclarationsMap.Remove(symbol);
-                }
-            }
         }
 
         internal class DeclarationAnalysisData
@@ -166,24 +128,5 @@ public static bool RemoveCachedSemanticModel(SyntaxTree tree, Compilation compil
             return s_compilationDataCache.TryGetValue(compilation, out compilationData) &&
                 compilationData.RemoveCachedSemanticModel(tree);
         }
-
-        public static bool TryGetCachedDeclaringReferences(ISymbol symbol, Compilation compilation, out ImmutableArray<SyntaxReference> declaringReferences)
-        {
-            var compilationData = GetOrCreateCachedCompilationData(compilation);
-            return compilationData.TryGetCachedDeclaringReferences(symbol, out declaringReferences);
-        }
-
-        public static void CacheDeclaringReferences(ISymbol symbol, Compilation compilation, ImmutableArray<SyntaxReference> declaringReferences)
-        {
-            var compilationData = GetOrCreateCachedCompilationData(compilation);
-            compilationData.CacheDeclaringReferences(symbol, declaringReferences);
-        }
-
-        public static bool RemoveCachedDeclaringReferences(ISymbol symbol, Compilation compilation)
-        {
-            CompilationData compilationData;
-            return s_compilationDataCache.TryGetValue(compilation, out compilationData) &&
-                compilationData.RemoveCachedDeclaringReferences(symbol);
-        }
     }
 }
\ No newline at end of file

src/Compilers/VisualBasic/Portable/Symbols/Source/SourceMemberContainerTypeSymbol.vb

@@ -1397,24 +1397,9 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Symbols
 
         Public NotOverridable Overrides ReadOnly Property DeclaringSyntaxReferences As ImmutableArray(Of SyntaxReference)
             Get
-                ' PERF: Declaring references are cached for compilations with event queue.
-                Return If(Me.DeclaringCompilation?.EventQueue IsNot Nothing, GetCachedDeclaringReferences(), ComputeDeclaringReferencesCore())
+                Return GetDeclaringSyntaxReferenceHelper(SyntaxReferences)
             End Get
         End Property
-
-        Private Function GetCachedDeclaringReferences() As ImmutableArray(Of SyntaxReference)
-            Dim declaringReferences As ImmutableArray(Of SyntaxReference) = Nothing
-            If Not Diagnostics.AnalyzerDriver.TryGetCachedDeclaringReferences(Me, DeclaringCompilation, declaringReferences) Then
-                declaringReferences = ComputeDeclaringReferencesCore()
-                Diagnostics.AnalyzerDriver.CacheDeclaringReferences(Me, DeclaringCompilation, declaringReferences)
-            End If
-
-            Return declaringReferences
-        End Function
-
-        Private Function ComputeDeclaringReferencesCore() As ImmutableArray(Of SyntaxReference)
-            Return GetDeclaringSyntaxReferenceHelper(SyntaxReferences)
-        End Function
 #End Region
 
 #Region "Member from Syntax"

src/Compilers/VisualBasic/Portable/Symbols/Source/SourceNamespaceSymbol.vb

@@ -391,21 +391,10 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Symbols
 
         Public Overrides ReadOnly Property DeclaringSyntaxReferences As ImmutableArray(Of SyntaxReference)
             Get
-                ' PERF: Declaring references are cached for compilations with event queue.
-                Return If(Me.DeclaringCompilation?.EventQueue IsNot Nothing, GetCachedDeclaringReferences(), ComputeDeclaringReferencesCore())
+                Return ComputeDeclaringReferencesCore()
             End Get
         End Property
 
-        Private Function GetCachedDeclaringReferences() As ImmutableArray(Of SyntaxReference)
-            Dim declaringReferences As ImmutableArray(Of SyntaxReference) = Nothing
-            If Not Diagnostics.AnalyzerDriver.TryGetCachedDeclaringReferences(Me, DeclaringCompilation, declaringReferences) Then
-                declaringReferences = ComputeDeclaringReferencesCore()
-                Diagnostics.AnalyzerDriver.CacheDeclaringReferences(Me, DeclaringCompilation, declaringReferences)
-            End If
-
-            Return declaringReferences
-        End Function
-
         Private Function ComputeDeclaringReferencesCore() As ImmutableArray(Of SyntaxReference)
             Dim declarations As ImmutableArray(Of SingleNamespaceDeclaration) = _declaration.Declarations