Cleanup: Delete NGen of T (#9263)

Context
The sole purpose of introducing the type seems to have been silencing a legacy code analyzer rule. The rule does not exist anymore / has not been brought over to Roslyn (dotnet/roslyn-analyzers#722) and it's now hurting performance, if anything. Types like HashSet<int> are part of the mscorlib native image and it's wasteful to duplicate the code in our binaries. The rest is handled by IBC/OptProf.

Changes Made
Deleted NGen and its uses.

Testing
Experimental insertion to confirm no regressions.

src/Build/BackEnd/BuildManager/BuildManager.cs

@@ -118,7 +118,7 @@ public class BuildManager : INodePacketHandler, IBuildComponentHost, IDisposable
         /// <summary>
         /// Set of active nodes in the system.
         /// </summary>
-        private readonly HashSet<NGen<int>> _activeNodes;
+        private readonly HashSet<int> _activeNodes;
 
         /// <summary>
         /// Event signalled when all nodes have shutdown.
@@ -128,7 +128,7 @@ public class BuildManager : INodePacketHandler, IBuildComponentHost, IDisposable
         /// <summary>
         /// Mapping of nodes to the configurations they know about.
         /// </summary>
-        private readonly Dictionary<NGen<int>, HashSet<NGen<int>>> _nodeIdToKnownConfigurations;
+        private readonly Dictionary<int, HashSet<int>> _nodeIdToKnownConfigurations;
 
         /// <summary>
         /// Flag indicating if we are currently shutting down.  When set, we stop processing packets other than NodeShutdown.
@@ -301,9 +301,9 @@ public BuildManager(string hostName)
             _buildSubmissions = new Dictionary<int, BuildSubmission>();
             _graphBuildSubmissions = new Dictionary<int, GraphBuildSubmission>();
             _noActiveSubmissionsEvent = new AutoResetEvent(true);
-            _activeNodes = new HashSet<NGen<int>>();
+            _activeNodes = new HashSet<int>();
             _noNodesActiveEvent = new AutoResetEvent(true);
-            _nodeIdToKnownConfigurations = new Dictionary<NGen<int>, HashSet<NGen<int>>>();
+            _nodeIdToKnownConfigurations = new Dictionary<int, HashSet<int>>();
             _unnamedProjectInstanceToNames = new Dictionary<ProjectInstance, string>();
             _nextUnnamedProjectId = 1;
             _componentFactories = new BuildComponentFactoryCollection(this);
@@ -2394,9 +2394,9 @@ private void HandleConfigurationRequest(int node, BuildRequestConfiguration unre
 
             var response = new BuildRequestConfigurationResponse(unresolvedConfiguration.ConfigurationId, resolvedConfiguration.ConfigurationId, resolvedConfiguration.ResultsNodeId);
 
-            if (!_nodeIdToKnownConfigurations.TryGetValue(node, out HashSet<NGen<int>> configurationsOnNode))
+            if (!_nodeIdToKnownConfigurations.TryGetValue(node, out HashSet<int> configurationsOnNode))
             {
-                configurationsOnNode = new HashSet<NGen<int>>();
+                configurationsOnNode = new HashSet<int>();
                 _nodeIdToKnownConfigurations[node] = configurationsOnNode;
             }
 
@@ -2664,7 +2664,7 @@ private void PerformSchedulingActions(IEnumerable<ScheduleResponse> responses)
                             // of which nodes have had configurations specifically assigned to them for building.  However, a node may
                             // have created a configuration based on a build request it needs to wait on.  In this
                             // case we need not send the configuration since it will already have been mapped earlier.
-                            if (!_nodeIdToKnownConfigurations.TryGetValue(response.NodeId, out HashSet<NGen<int>> configurationsOnNode) ||
+                            if (!_nodeIdToKnownConfigurations.TryGetValue(response.NodeId, out HashSet<int> configurationsOnNode) ||
                                !configurationsOnNode.Contains(response.BuildRequest.ConfigurationId))
                             {
                                 IConfigCache configCache = _componentFactories.GetComponent(BuildComponentType.ConfigCache) as IConfigCache;

src/Build/BackEnd/Components/BuildRequestEngine/BuildRequestEngine.cs

@@ -1122,7 +1122,7 @@ private void IssueBuildRequests(BuildRequestEntry issuingEntry, FullyQualifiedBu
             lock (issuingEntry.GlobalLock)
             {
                 var existingResultsToReport = new List<BuildResult>();
-                var unresolvedConfigurationsAdded = new HashSet<NGen<int>>();
+                var unresolvedConfigurationsAdded = new HashSet<int>();
 
                 foreach (FullyQualifiedBuildRequest request in newRequests)
                 {

src/Build/Evaluation/Evaluator.cs

@@ -115,7 +115,7 @@ internal class Evaluator<P, I, M, D>
         /// Dictionary of project full paths and a boolean that indicates whether at least one
         /// of their targets has the "Returns" attribute set.
         /// </summary>
-        private readonly Dictionary<ProjectRootElement, NGen<bool>> _projectSupportsReturnsAttribute;
+        private readonly Dictionary<ProjectRootElement, bool> _projectSupportsReturnsAttribute;
 
         /// <summary>
         /// The Project Xml to be evaluated.
@@ -253,7 +253,7 @@ private Evaluator(
             _targetElements = new List<ProjectTargetElement>();
             _importsSeen = new Dictionary<string, ProjectImportElement>(StringComparer.OrdinalIgnoreCase);
             _initialTargetsList = new List<string>();
-            _projectSupportsReturnsAttribute = new Dictionary<ProjectRootElement, NGen<bool>>();
+            _projectSupportsReturnsAttribute = new Dictionary<ProjectRootElement, bool>();
             _projectRootElement = projectRootElement;
             _loadSettings = loadSettings;
             _maxNodeCount = maxNodeCount;
@@ -901,7 +901,7 @@ private void PerformDepthFirstPass(ProjectRootElement currentProjectOrImport)
                             break;
                         case ProjectTargetElement target:
                             // Defaults to false
-                            _projectSupportsReturnsAttribute.TryGetValue(currentProjectOrImport, out NGen<bool> projectSupportsReturnsAttribute);
+                            _projectSupportsReturnsAttribute.TryGetValue(currentProjectOrImport, out bool projectSupportsReturnsAttribute);
 
                             _projectSupportsReturnsAttribute[currentProjectOrImport] = projectSupportsReturnsAttribute || (target.Returns != null);
                             _targetElements.Add(target);

src/Build/Microsoft.Build.csproj

@@ -82,9 +82,6 @@
     <Compile Include="..\Shared\IConstrainedEqualityComparer.cs">
       <Link>IConstrainedEqualityComparer.cs</Link>
     </Compile>
-    <Compile Include="..\Shared\NGen.cs">
-      <Link>SharedUtilities\NGen.cs</Link>
-    </Compile>
     <Compile Include="..\Shared\PropertyParser.cs">
       <Link>BackEnd\Components\RequestBuilder\IntrinsicTasks\PropertyParser.cs</Link>
     </Compile>

src/Tasks/ManifestUtil/ApplicationManifest.cs

@@ -640,7 +640,7 @@ private void ValidateReferencesForClickOnceApplication()
         {
             int t1 = Environment.TickCount;
             bool isPartialTrust = !TrustInfo.IsFullTrust;
-            var targetPathList = new Dictionary<string, NGen<bool>>();
+            var targetPathList = new Dictionary<string, bool>();
 
             foreach (AssemblyReference assembly in AssemblyReferences)
             {

src/Tasks/ManifestUtil/Manifest.cs

@@ -611,7 +611,7 @@ private void ValidateReferences()
                 return;
             }
 
-            var identityList = new Dictionary<string, NGen<bool>>();
+            var identityList = new Dictionary<string, bool>();
             foreach (AssemblyReference assembly in AssemblyReferences)
             {
                 if (assembly.AssemblyIdentity != null)

src/Tasks/Microsoft.Build.Tasks.csproj

@@ -73,9 +73,6 @@
     <Compile Include="..\Shared\FileDelegates.cs">
       <Link>FileDelegates.cs</Link>
     </Compile>
-    <Compile Include="..\Shared\NGen.cs">
-      <Link>NGen.cs</Link>
-    </Compile>
     <Compile Include="..\Shared\IConstrainedEqualityComparer.cs" />
     <Compile Include="..\Shared\PropertyParser.cs">
       <Link>PropertyParser.cs</Link>

src/Tasks/RedistList.cs

@@ -48,7 +48,7 @@ internal sealed class RedistList
         /// When we check to see if an assembly is in this redist list we want to cache it so that if we ask again we do not
         /// have to re-scan bits of the redist list and do the assemblynameExtension comparisons.
         /// </summary>
-        private readonly ConcurrentDictionary<AssemblyNameExtension, NGen<bool>> _assemblyNameInRedist = new ConcurrentDictionary<AssemblyNameExtension, NGen<bool>>(AssemblyNameComparer.GenericComparer);
+        private readonly ConcurrentDictionary<AssemblyNameExtension, bool> _assemblyNameInRedist = new ConcurrentDictionary<AssemblyNameExtension, bool>(AssemblyNameComparer.GenericComparer);
 
         /// <summary>
         /// AssemblyName to unified assemblyName. We make this kind of call a lot and also will ask for the same name multiple times.
@@ -431,7 +431,7 @@ public bool FrameworkAssemblyEntryInRedist(AssemblyNameExtension assemblyName)
         {
             ErrorUtilities.VerifyThrowArgumentNull(assemblyName, nameof(assemblyName));
 
-            if (!_assemblyNameInRedist.TryGetValue(assemblyName, out NGen<bool> isAssemblyNameInRedist))
+            if (!_assemblyNameInRedist.TryGetValue(assemblyName, out bool isAssemblyNameInRedist))
             {
                 string simpleName = GetSimpleName(assemblyName.Name);
                 if (_simpleNameMap.TryGetValue(simpleName, out int index))