CQ. Remove not useful _ParsedFileStateCache.

It was used to support macros, so is not useful anymore.

Change-Id: I12b98ed75125bc59473c9048a9f35554b5f33eae
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/435561
Reviewed-by: Paul Berry <paulberry@google.com>
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>

pkg/analyzer/lib/src/dart/analysis/driver.dart

@@ -574,9 +574,7 @@ class AnalysisDriver {
     addFile(file.path);
   }
 
-  void afterPerformWork() {
-    _fsState.clearParsedFileStateCache();
-  }
+  void afterPerformWork() {}
 
   /// Return a [Future] that completes after pending file changes are applied,
   /// so that [currentSession] can be used to compute results.

pkg/analyzer/lib/src/dart/analysis/file_state.dart

@@ -13,7 +13,6 @@ import 'package:analyzer/dart/analysis/declared_variables.dart';
 import 'package:analyzer/dart/analysis/features.dart';
 import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/dart/element/element.dart';
-import 'package:analyzer/diagnostic/diagnostic.dart';
 import 'package:analyzer/error/listener.dart';
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/source/file_source.dart';
@@ -656,7 +655,6 @@ class FileState {
     var rawFileState = _fsState.fileContentStrategy.get(path);
     var contentChanged = _fileContent?.contentHash != rawFileState.contentHash;
     _fileContent = rawFileState;
-    _fsState._parsedFileStateCache.remove(this);
 
     // Prepare the unlinked bundle key.
     var previousUnlinkedKey = _unlinkedKey;
@@ -802,30 +800,6 @@ class FileState {
     return _fsState.getFileForUri(absoluteUri);
   }
 
-  /// Returns either new, or cached parsed result for this file.
-  _ParsedFileState _getParsed({required OperationPerformanceImpl performance}) {
-    var result = _fsState._parsedFileStateCache.get(this);
-    if (result != null) {
-      return result;
-    }
-
-    var diagnosticListener = RecordingDiagnosticListener();
-    var unit = parseCode(
-      code: content,
-      diagnosticListener: diagnosticListener,
-      performance: performance,
-    );
-
-    result = _ParsedFileState(
-      code: content,
-      unit: unit,
-      diagnostics: diagnosticListener.diagnostics,
-    );
-    _fsState._parsedFileStateCache.put(this, result);
-
-    return result;
-  }
-
   /// Return the unlinked unit, freshly deserialized from bytes,
   /// previously deserialized from bytes, or new.
   AnalysisDriverUnlinkedUnit _getUnlinkedUnit(
@@ -855,7 +829,7 @@ class FileState {
       return result;
     }
 
-    var unit = _getParsed(performance: performance).unit;
+    var unit = parse(performance: performance);
 
     return performance.run('compute', (performance) {
       var unlinkedUnit = performance.run('serializeAstUnlinked2', (
@@ -1280,12 +1254,6 @@ class FileSystemState {
   /// store here the instance to attach [_newFile] operations.
   OperationPerformanceImpl? newFileOperationPerformance;
 
-  /// We cache results of parsing [FileState]s because they might be useful
-  /// in the process of a single analysis operation. But after that, even
-  /// if these results are still valid, they are often never used again. So,
-  /// currently we clear the cache after each operation.
-  final _ParsedFileStateCache _parsedFileStateCache = _ParsedFileStateCache();
-
   FileSystemState(
     this._byteStore,
     this.resourceProvider,
@@ -1340,11 +1308,6 @@ class FileSystemState {
     }
   }
 
-  /// Clears the parsed file state cache.
-  void clearParsedFileStateCache() {
-    _parsedFileStateCache.clear();
-  }
-
   /// Collected files that transitively reference a file with the [path].
   /// These files are potentially affected by the change.
   void collectAffected(String path, Set<FileState> affected) {
@@ -2399,38 +2362,6 @@ class _LibraryNameToFiles {
   }
 }
 
-class _ParsedFileState {
-  final String code;
-  final CompilationUnitImpl unit;
-  final List<Diagnostic> diagnostics;
-
-  _ParsedFileState({
-    required this.code,
-    required this.unit,
-    required this.diagnostics,
-  });
-}
-
-class _ParsedFileStateCache {
-  final Map<FileState, _ParsedFileState> _map = Map.identity();
-
-  void clear() {
-    _map.clear();
-  }
-
-  _ParsedFileState? get(FileState file) {
-    return _map[file];
-  }
-
-  void put(FileState file, _ParsedFileState result) {
-    _map[file] = result;
-  }
-
-  void remove(FileState file) {
-    _map.remove(file);
-  }
-}
-
 extension on List<DirectiveState> {
   void disposeAll() {
     for (var directive in this) {

pkg/analyzer/lib/src/dart/micro/resolve_file.dart

@@ -304,7 +304,6 @@ class FileResolver {
         for (var filePath in result) {
           await collectReferences2(filePath, performance!);
         }
-        _clearFileSystemStateParsedCache();
       }
       return references;
     });
@@ -415,7 +414,6 @@ class FileResolver {
 
     performance.run('libraryContext', (performance) {
       libraryContext!.load(targetLibrary: kind, performance: performance);
-      _clearFileSystemStateParsedCache();
     });
 
     return libraryContext!.elementFactory.libraryOfUri2(uri);
@@ -515,7 +513,6 @@ class FileResolver {
         path: libraryFile.path,
         performance: performance,
       );
-      _clearFileSystemStateParsedCache();
       var unit = libraryResult.units.firstWhereOrNull(
         (unitResult) => unitResult.path == path,
       );
@@ -575,7 +572,6 @@ class FileResolver {
           performance: OperationPerformanceImpl('<root>'),
           typeSystemOperations: typeSystemOperations,
         );
-        _clearFileSystemStateParsedCache();
 
         var analysisResult = performance!.run('analyze', (performance) {
           return libraryAnalyzer.analyzeForCompletion(
@@ -678,10 +674,6 @@ class FileResolver {
     });
   }
 
-  void _clearFileSystemStateParsedCache() {
-    fsState?.clearParsedFileStateCache();
-  }
-
   /// Make sure that [fsState], [contextObjects], and [libraryContext] are
   /// created and configured with the given [fileAnalysisOptions].
   ///
@@ -695,10 +687,6 @@ class FileResolver {
   /// system. And there are lints that are enabled for one package, but not
   /// for another.
   void _createContext(String path, AnalysisOptionsImpl fileAnalysisOptions) {
-    // Clear it here too, so that even if we miss the invocation somewhere,
-    // we still eventually do it, and so limit the number of cached items.
-    _clearFileSystemStateParsedCache();
-
     if (contextObjects != null) {
       libraryContext!.analysisContext.analysisOptions = fileAnalysisOptions;
       return;