Allocate less in GetTypeByMetadataName

src/Compilers/CSharp/Portable/Symbols/AnonymousTypes/PublicSymbols/AnonymousManager.TypeOrDelegatePublicSymbol.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using System;
 using System.Collections.Generic;
 using System.Collections.Immutable;
 using System.Runtime.InteropServices;
@@ -132,12 +133,12 @@ public sealed override ImmutableArray<NamedTypeSymbol> GetTypeMembers()
                 return ImmutableArray<NamedTypeSymbol>.Empty;
             }
 
-            public sealed override ImmutableArray<NamedTypeSymbol> GetTypeMembers(string name)
+            public sealed override ImmutableArray<NamedTypeSymbol> GetTypeMembers(ReadOnlyMemory<char> name)
             {
                 return ImmutableArray<NamedTypeSymbol>.Empty;
             }
 
-            public sealed override ImmutableArray<NamedTypeSymbol> GetTypeMembers(string name, int arity)
+            public sealed override ImmutableArray<NamedTypeSymbol> GetTypeMembers(ReadOnlyMemory<char> name, int arity)
             {
                 return ImmutableArray<NamedTypeSymbol>.Empty;
             }

src/Compilers/CSharp/Portable/Symbols/AnonymousTypes/SynthesizedSymbols/AnonymousType.TypeOrDelegateTemplateSymbol.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using System;
 using System.Collections.Generic;
 using System.Collections.Immutable;
 using System.Diagnostics;
@@ -180,12 +181,12 @@ public sealed override ImmutableArray<NamedTypeSymbol> GetTypeMembers()
                 return ImmutableArray<NamedTypeSymbol>.Empty;
             }
 
-            public sealed override ImmutableArray<NamedTypeSymbol> GetTypeMembers(string name)
+            public sealed override ImmutableArray<NamedTypeSymbol> GetTypeMembers(ReadOnlyMemory<char> name)
             {
                 return ImmutableArray<NamedTypeSymbol>.Empty;
             }
 
-            public sealed override ImmutableArray<NamedTypeSymbol> GetTypeMembers(string name, int arity)
+            public sealed override ImmutableArray<NamedTypeSymbol> GetTypeMembers(ReadOnlyMemory<char> name, int arity)
             {
                 return ImmutableArray<NamedTypeSymbol>.Empty;
             }

src/Compilers/CSharp/Portable/Symbols/ArrayTypeSymbol.cs

@@ -272,12 +272,12 @@ public override ImmutableArray<NamedTypeSymbol> GetTypeMembers()
             return ImmutableArray<NamedTypeSymbol>.Empty;
         }
 
-        public override ImmutableArray<NamedTypeSymbol> GetTypeMembers(string name)
+        public override ImmutableArray<NamedTypeSymbol> GetTypeMembers(ReadOnlyMemory<char> name)
         {
             return ImmutableArray<NamedTypeSymbol>.Empty;
         }
 
-        public override ImmutableArray<NamedTypeSymbol> GetTypeMembers(string name, int arity)
+        public override ImmutableArray<NamedTypeSymbol> GetTypeMembers(ReadOnlyMemory<char> name, int arity)
         {
             return ImmutableArray<NamedTypeSymbol>.Empty;
         }

src/Compilers/CSharp/Portable/Symbols/DynamicTypeSymbol.cs

@@ -139,7 +139,7 @@ public override ImmutableArray<Symbol> GetMembers(string name)
             return ImmutableArray<Symbol>.Empty;
         }
 
-        public override ImmutableArray<NamedTypeSymbol> GetTypeMembers(string name)
+        public override ImmutableArray<NamedTypeSymbol> GetTypeMembers(ReadOnlyMemory<char> name)
         {
             return ImmutableArray<NamedTypeSymbol>.Empty;
         }

src/Compilers/CSharp/Portable/Symbols/ErrorTypeSymbol.cs

@@ -2,11 +2,12 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using Roslyn.Utilities;
+using System;
 using System.Collections.Generic;
 using System.Collections.Immutable;
 using System.Diagnostics;
 using System.Runtime.InteropServices;
+using Roslyn.Utilities;
 
 namespace Microsoft.CodeAnalysis.CSharp.Symbols
 {
@@ -190,7 +191,7 @@ public override ImmutableArray<NamedTypeSymbol> GetTypeMembers()
         /// <returns>An ImmutableArray containing all the types that are members of this symbol with the given name.
         /// If this symbol has no type members with this name,
         /// returns an empty ImmutableArray. Never returns null.</returns>
-        public override ImmutableArray<NamedTypeSymbol> GetTypeMembers(string name)
+        public override ImmutableArray<NamedTypeSymbol> GetTypeMembers(ReadOnlyMemory<char> name)
         {
             return ImmutableArray<NamedTypeSymbol>.Empty;
         }
@@ -201,7 +202,7 @@ public override ImmutableArray<NamedTypeSymbol> GetTypeMembers(string name)
         /// <returns>An ImmutableArray containing all the types that are members of this symbol with the given name and arity.
         /// If this symbol has no type members with this name and arity,
         /// returns an empty ImmutableArray. Never returns null.</returns>
-        public override ImmutableArray<NamedTypeSymbol> GetTypeMembers(string name, int arity)
+        public override ImmutableArray<NamedTypeSymbol> GetTypeMembers(ReadOnlyMemory<char> name, int arity)
         {
             return ImmutableArray<NamedTypeSymbol>.Empty;
         }

src/Compilers/CSharp/Portable/Symbols/FunctionPointers/FunctionPointerTypeSymbol.cs

@@ -92,7 +92,7 @@ private FunctionPointerTypeSymbol(FunctionPointerMethodSymbol signature)
         public override ImmutableArray<Symbol> GetMembers() => ImmutableArray<Symbol>.Empty;
         public override ImmutableArray<Symbol> GetMembers(string name) => ImmutableArray<Symbol>.Empty;
         public override ImmutableArray<NamedTypeSymbol> GetTypeMembers() => ImmutableArray<NamedTypeSymbol>.Empty;
-        public override ImmutableArray<NamedTypeSymbol> GetTypeMembers(string name) => ImmutableArray<NamedTypeSymbol>.Empty;
+        public override ImmutableArray<NamedTypeSymbol> GetTypeMembers(ReadOnlyMemory<char> name) => ImmutableArray<NamedTypeSymbol>.Empty;
         internal override TResult Accept<TArgument, TResult>(CSharpSymbolVisitor<TArgument, TResult> visitor, TArgument a) => visitor.VisitFunctionPointerType(this, a);
         internal override ImmutableArray<NamedTypeSymbol> InterfacesNoUseSiteDiagnostics(ConsList<TypeSymbol>? basesBeingResolved = null) => ImmutableArray<NamedTypeSymbol>.Empty;
 

src/Compilers/CSharp/Portable/Symbols/FunctionTypeSymbol.cs

@@ -139,7 +139,7 @@ internal void SetExpression(BoundExpression expression)
 
         public override ImmutableArray<NamedTypeSymbol> GetTypeMembers() => throw ExceptionUtilities.Unreachable();
 
-        public override ImmutableArray<NamedTypeSymbol> GetTypeMembers(string name) => throw ExceptionUtilities.Unreachable();
+        public override ImmutableArray<NamedTypeSymbol> GetTypeMembers(ReadOnlyMemory<char> name) => throw ExceptionUtilities.Unreachable();
 
         protected override ISymbol CreateISymbol() => throw ExceptionUtilities.Unreachable();
 

src/Compilers/CSharp/Portable/Symbols/MergedNamespaceSymbol.cs

@@ -43,7 +43,7 @@ internal sealed class MergedNamespaceSymbol : NamespaceSymbol
         // The cachedLookup caches results of lookups on the constituent namespaces so that
         // subsequent lookups for the same name are much faster than having to ask each of the
         // constituent namespaces.
-        private readonly CachingDictionary<string, Symbol> _cachedLookup;
+        private readonly CachingDictionary<ReadOnlyMemory<char>, Symbol> _cachedLookup;
 
         // GetMembers() is repeatedly called on merged namespaces in some IDE scenarios.
         // This caches the result that is built by asking the 'cachedLookup' for a concatenated
@@ -93,7 +93,7 @@ private MergedNamespaceSymbol(NamespaceExtent extent, NamespaceSymbol containing
             _extent = extent;
             _namespacesToMerge = namespacesToMerge;
             _containingNamespace = containingNamespace;
-            _cachedLookup = new CachingDictionary<string, Symbol>(SlowGetChildrenOfName, SlowGetChildNames, EqualityComparer<string>.Default);
+            _cachedLookup = new CachingDictionary<ReadOnlyMemory<char>, Symbol>(SlowGetChildrenOfName, SlowGetChildNames, ReadOnlyMemoryOfCharComparer.Instance);
             _nameOpt = nameOpt;
 
 #if DEBUG
@@ -132,7 +132,7 @@ internal override void ForceComplete(SourceLocation locationOpt, CancellationTok
         /// Method that is called from the CachingLookup to lookup the children of a given name.
         /// Looks in all the constituent namespaces.
         /// </summary>
-        private ImmutableArray<Symbol> SlowGetChildrenOfName(string name)
+        private ImmutableArray<Symbol> SlowGetChildrenOfName(ReadOnlyMemory<char> name)
         {
             ArrayBuilder<NamespaceSymbol> namespaceSymbols = null;
             var otherSymbols = ArrayBuilder<Symbol>.GetInstance();
@@ -166,15 +166,15 @@ private ImmutableArray<Symbol> SlowGetChildrenOfName(string name)
         /// Method that is called from the CachingLookup to get all child names. Looks in all
         /// constituent namespaces.
         /// </summary>
-        private HashSet<string> SlowGetChildNames(IEqualityComparer<string> comparer)
+        private HashSet<ReadOnlyMemory<char>> SlowGetChildNames(IEqualityComparer<ReadOnlyMemory<char>> comparer)
         {
-            var childNames = new HashSet<string>(comparer);
+            var childNames = new HashSet<ReadOnlyMemory<char>>(comparer);
 
             foreach (var ns in _namespacesToMerge)
             {
                 foreach (var child in ns.GetMembersUnordered())
                 {
-                    childNames.Add(child.Name);
+                    childNames.Add(child.Name.AsMemory());
                 }
             }
 
@@ -218,7 +218,7 @@ public override ImmutableArray<Symbol> GetMembers()
             return _allMembers;
         }
 
-        public override ImmutableArray<Symbol> GetMembers(string name)
+        public override ImmutableArray<Symbol> GetMembers(ReadOnlyMemory<char> name)
         {
             return _cachedLookup[name];
         }
@@ -233,7 +233,7 @@ public sealed override ImmutableArray<NamedTypeSymbol> GetTypeMembers()
             return ImmutableArray.CreateRange<NamedTypeSymbol>(GetMembers().OfType<NamedTypeSymbol>());
         }
 
-        public override ImmutableArray<NamedTypeSymbol> GetTypeMembers(string name)
+        public override ImmutableArray<NamedTypeSymbol> GetTypeMembers(ReadOnlyMemory<char> name)
         {
             // TODO - This is really inefficient. Creating a new array on each lookup needs to fixed!
             return ImmutableArray.CreateRange<NamedTypeSymbol>(_cachedLookup[name].OfType<NamedTypeSymbol>());

src/Compilers/CSharp/Portable/Symbols/Metadata/PE/PEModuleSymbol.cs

@@ -476,7 +476,7 @@ private ImmutableArray<CSharpAttributeData> GetCustomAttributesFilterCompilerAtt
         }
 
         internal void OnNewTypeDeclarationsLoaded(
-            Dictionary<string, ImmutableArray<PENamedTypeSymbol>> typesDict)
+            Dictionary<ReadOnlyMemory<char>, ImmutableArray<PENamedTypeSymbol>> typesDict)
         {
             bool keepLookingForDeclaredCorTypes = (_ordinal == 0 && _assemblySymbol.KeepLookingForDeclaredSpecialTypes);
 
@@ -691,7 +691,7 @@ internal override CharSet? DefaultMarshallingCharSet
         internal NamedTypeSymbol LookupTopLevelMetadataTypeWithNoPiaLocalTypeUnification(ref MetadataTypeName emittedName, out bool isNoPiaLocalType)
         {
             NamedTypeSymbol? result;
-            var scope = (PENamespaceSymbol?)this.GlobalNamespace.LookupNestedNamespace(emittedName.NamespaceSegments);
+            var scope = (PENamespaceSymbol?)this.GlobalNamespace.LookupNestedNamespace(emittedName.NamespaceSegmentsMemory);
 
             if ((object?)scope == null)
             {

src/Compilers/CSharp/Portable/Symbols/Metadata/PE/PENamedTypeSymbol.cs

@@ -27,7 +27,8 @@ namespace Microsoft.CodeAnalysis.CSharp.Symbols.Metadata.PE
     /// </summary>
     internal abstract class PENamedTypeSymbol : NamedTypeSymbol
     {
-        private static readonly Dictionary<string, ImmutableArray<PENamedTypeSymbol>> s_emptyNestedTypes = new Dictionary<string, ImmutableArray<PENamedTypeSymbol>>(EmptyComparer.Instance);
+        private static readonly Dictionary<ReadOnlyMemory<char>, ImmutableArray<PENamedTypeSymbol>> s_emptyNestedTypes =
+            new Dictionary<ReadOnlyMemory<char>, ImmutableArray<PENamedTypeSymbol>>(EmptyReadOnlyMemoryOfCharComparer.Instance);
 
         private readonly NamespaceOrTypeSymbol _container;
         private readonly TypeDefinitionHandle _handle;
@@ -60,7 +61,7 @@ internal abstract class PENamedTypeSymbol : NamedTypeSymbol
         /// A map of types immediately contained within this type 
         /// grouped by their name (case-sensitively).
         /// </summary>
-        private Dictionary<string, ImmutableArray<PENamedTypeSymbol>> _lazyNestedTypes;
+        private Dictionary<ReadOnlyMemory<char>, ImmutableArray<PENamedTypeSymbol>> _lazyNestedTypes;
 
         /// <summary>
         /// Lazily initialized by TypeKind property.
@@ -1509,7 +1510,7 @@ public override ImmutableArray<Symbol> GetMembers(string name)
 
             // nested types are not common, but we need to check just in case
             ImmutableArray<PENamedTypeSymbol> t;
-            if (_lazyNestedTypes.TryGetValue(name, out t))
+            if (_lazyNestedTypes.TryGetValue(name.AsMemory(), out t))
             {
                 m = m.Concat(StaticCast<Symbol>.From(t));
             }
@@ -1578,7 +1579,7 @@ private void EnsureNestedTypesAreLoaded()
             }
         }
 
-        public override ImmutableArray<NamedTypeSymbol> GetTypeMembers(string name)
+        public override ImmutableArray<NamedTypeSymbol> GetTypeMembers(ReadOnlyMemory<char> name)
         {
             EnsureNestedTypesAreLoaded();
 
@@ -1592,7 +1593,7 @@ public override ImmutableArray<NamedTypeSymbol> GetTypeMembers(string name)
             return ImmutableArray<NamedTypeSymbol>.Empty;
         }
 
-        public override ImmutableArray<NamedTypeSymbol> GetTypeMembers(string name, int arity)
+        public override ImmutableArray<NamedTypeSymbol> GetTypeMembers(ReadOnlyMemory<char> name, int arity)
         {
             return GetTypeMembers(name).WhereAsArray((type, arity) => type.Arity == arity, arity);
         }
@@ -2056,14 +2057,14 @@ private static Dictionary<string, ImmutableArray<Symbol>> GroupByName(ArrayBuild
             return symbols.ToDictionary(s => s.Name, StringOrdinalComparer.Instance);
         }
 
-        private static Dictionary<string, ImmutableArray<PENamedTypeSymbol>> GroupByName(ArrayBuilder<PENamedTypeSymbol> symbols)
+        private static Dictionary<ReadOnlyMemory<char>, ImmutableArray<PENamedTypeSymbol>> GroupByName(ArrayBuilder<PENamedTypeSymbol> symbols)
         {
             if (symbols.Count == 0)
             {
                 return s_emptyNestedTypes;
             }
 
-            return symbols.ToDictionary(s => s.Name, StringOrdinalComparer.Instance);
+            return symbols.ToDictionary(s => s.Name.AsMemory(), ReadOnlyMemoryOfCharComparer.Instance);
         }
 
         internal override UseSiteInfo<AssemblySymbol> GetUseSiteInfo()

src/Compilers/CSharp/Portable/Symbols/Metadata/PE/PENamespaceSymbol.cs

@@ -27,13 +27,13 @@ internal abstract class PENamespaceSymbol
         /// A map of namespaces immediately contained within this namespace 
         /// mapped by their name (case-sensitively).
         /// </summary>
-        protected Dictionary<string, PENestedNamespaceSymbol> lazyNamespaces;
+        protected Dictionary<ReadOnlyMemory<char>, PENestedNamespaceSymbol> lazyNamespaces;
 
         /// <summary>
         /// A map of types immediately contained within this namespace 
         /// grouped by their name (case-sensitively).
         /// </summary>
-        protected Dictionary<string, ImmutableArray<PENamedTypeSymbol>> lazyTypes;
+        protected Dictionary<ReadOnlyMemory<char>, ImmutableArray<PENamedTypeSymbol>> lazyTypes;
 
         /// <summary>
         /// A map of NoPia local types immediately contained in this assembly.
@@ -87,7 +87,7 @@ private ImmutableArray<NamedTypeSymbol> GetMemberTypesPrivate()
             return StaticCast<NamedTypeSymbol>.From(_lazyFlattenedTypes);
         }
 
-        public sealed override ImmutableArray<Symbol> GetMembers(string name)
+        public sealed override ImmutableArray<Symbol> GetMembers(ReadOnlyMemory<char> name)
         {
             EnsureAllMembersLoaded();
 
@@ -121,7 +121,7 @@ public sealed override ImmutableArray<NamedTypeSymbol> GetTypeMembers()
             return GetMemberTypesPrivate();
         }
 
-        public sealed override ImmutableArray<NamedTypeSymbol> GetTypeMembers(string name)
+        public sealed override ImmutableArray<NamedTypeSymbol> GetTypeMembers(ReadOnlyMemory<char> name)
         {
             EnsureAllMembersLoaded();
 
@@ -132,7 +132,7 @@ public sealed override ImmutableArray<NamedTypeSymbol> GetTypeMembers(string nam
                 : ImmutableArray<NamedTypeSymbol>.Empty;
         }
 
-        public sealed override ImmutableArray<NamedTypeSymbol> GetTypeMembers(string name, int arity)
+        public sealed override ImmutableArray<NamedTypeSymbol> GetTypeMembers(ReadOnlyMemory<char> name, int arity)
         {
             return GetTypeMembers(name).WhereAsArray((type, arity) => type.Arity == arity, arity);
         }
@@ -224,12 +224,12 @@ private void LazyInitializeNamespaces(
         {
             if (this.lazyNamespaces == null)
             {
-                var namespaces = new Dictionary<string, PENestedNamespaceSymbol>(StringOrdinalComparer.Instance);
+                var namespaces = new Dictionary<ReadOnlyMemory<char>, PENestedNamespaceSymbol>(ReadOnlyMemoryOfCharComparer.Instance);
 
                 foreach (var child in childNamespaces)
                 {
                     var c = new PENestedNamespaceSymbol(child.Key, this, child.Value);
-                    namespaces.Add(c.Name, c);
+                    namespaces.Add(c.Name.AsMemory(), c);
                 }
 
                 Interlocked.CompareExchange(ref this.lazyNamespaces, namespaces, null);
@@ -276,7 +276,7 @@ private void LazyInitializeTypes(IEnumerable<IGrouping<string, TypeDefinitionHan
                     }
                 }
 
-                var typesDict = children.ToDictionary(c => c.Name, StringOrdinalComparer.Instance);
+                var typesDict = children.ToDictionary(c => c.Name.AsMemory(), ReadOnlyMemoryOfCharComparer.Instance);
                 children.Free();
 
                 if (noPiaLocalTypes != null)

src/Compilers/CSharp/Portable/Symbols/MissingNamespaceSymbol.cs

@@ -4,13 +4,10 @@
 
 #nullable disable
 
-using System.Collections.Generic;
+using System;
 using System.Collections.Immutable;
-using Microsoft.CodeAnalysis.CSharp.Symbols;
-using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Text;
-using Roslyn.Utilities;
 using System.Diagnostics;
+using Roslyn.Utilities;
 
 namespace Microsoft.CodeAnalysis.CSharp.Symbols
 {
@@ -115,12 +112,12 @@ public override ImmutableArray<NamedTypeSymbol> GetTypeMembers()
             return ImmutableArray<NamedTypeSymbol>.Empty;
         }
 
-        public override ImmutableArray<NamedTypeSymbol> GetTypeMembers(string name)
+        public override ImmutableArray<NamedTypeSymbol> GetTypeMembers(ReadOnlyMemory<char> name)
         {
             return ImmutableArray<NamedTypeSymbol>.Empty;
         }
 
-        public override ImmutableArray<NamedTypeSymbol> GetTypeMembers(string name, int arity)
+        public override ImmutableArray<NamedTypeSymbol> GetTypeMembers(ReadOnlyMemory<char> name, int arity)
         {
             return ImmutableArray<NamedTypeSymbol>.Empty;
         }
@@ -130,7 +127,7 @@ public override ImmutableArray<Symbol> GetMembers()
             return ImmutableArray<Symbol>.Empty;
         }
 
-        public override ImmutableArray<Symbol> GetMembers(string name)
+        public override ImmutableArray<Symbol> GetMembers(ReadOnlyMemory<char> name)
         {
             return ImmutableArray<Symbol>.Empty;
         }