[Dependency Scanning] Refactor 'ModuleDependenciesCache' to not hold a reference to the global 'SwiftDependencyScanningService'

While this made sense in the distant past where the scanning service provided backing storage for the dependency cache, it no longer does so and now makes for awkard layering where clients get at the service via the cache. Now the cache is a simple data structure while all the clients that need access to the scanning service will get it explicitly.

Author: artemcm

include/swift/AST/ModuleDependencies.h

@@ -992,7 +992,7 @@ class SwiftDependencyScanningService {
   std::shared_ptr<llvm::cas::ActionCache> ActionCache;
 
   /// File prefix mapper.
-  std::unique_ptr<llvm::PrefixMapper> Mapper;
+  std::shared_ptr<llvm::PrefixMapper> Mapper;
 
   /// The global file system cache.
   std::optional<
@@ -1073,7 +1073,6 @@ class SwiftDependencyScanningService {
 /// found within the current scanning action.
 class ModuleDependenciesCache {
 private:
-  SwiftDependencyScanningService &globalScanningService;
   /// Discovered dependencies
   ModuleDependenciesKindMap ModuleDependenciesMap;
   /// Set containing all of the Clang modules that have already been seen.
@@ -1094,8 +1093,7 @@ class ModuleDependenciesCache {
   getDependencyReferencesMap(ModuleDependencyKind kind) const;
 
 public:
-  ModuleDependenciesCache(SwiftDependencyScanningService &globalScanningService,
-                          const std::string &mainScanModuleName,
+  ModuleDependenciesCache(const std::string &mainScanModuleName,
                           const std::string &scanningContextHash);
   ModuleDependenciesCache(const ModuleDependenciesCache &) = delete;
   ModuleDependenciesCache &operator=(const ModuleDependenciesCache &) = delete;
@@ -1116,12 +1114,6 @@ class ModuleDependenciesCache {
   /// Whether we have cached dependency information for the given Swift module.
   bool hasSwiftDependency(StringRef moduleName) const;
 
-  SwiftDependencyScanningService &getScanService() {
-    return globalScanningService;
-  }
-  const SwiftDependencyScanningService &getScanService() const {
-    return globalScanningService;
-  }
   const llvm::DenseSet<clang::tooling::dependencies::ModuleID> &
   getAlreadySeenClangModules() const {
     return alreadySeenClangModules;

include/swift/ClangImporter/ClangImporter.h

@@ -503,7 +503,6 @@ class ClangImporter final : public ClangModuleLoader {
       const ASTContext &ctx,
       clang::tooling::dependencies::DependencyScanningTool &clangScanningTool,
       clang::tooling::dependencies::ModuleDepsGraph &clangDependencies,
-      StringRef moduleOutputPath, StringRef stableModuleOutputPath,
       LookupModuleOutputCallback LookupModuleOutput,
       RemapPathCallback remapPath = nullptr);
 

include/swift/DependencyScan/ModuleDependencyScanner.h

@@ -40,8 +40,7 @@ class ModuleDependencyScanningWorker {
   ModuleDependencyVector scanFilesystemForClangModuleDependency(
       Identifier moduleName,
       const llvm::DenseSet<clang::tooling::dependencies::ModuleID>
-          &alreadySeenModules,
-      llvm::PrefixMapper *prefixMapper);
+          &alreadySeenModules);
 
   /// Retrieve the module dependencies for the Swift module with the given name.
   ModuleDependencyVector scanFilesystemForSwiftModuleDependency(
@@ -89,6 +88,17 @@ class ModuleDependencyScanningWorker {
   // Swift and Clang module loaders acting as scanners.
   std::unique_ptr<SwiftModuleScanner> swiftModuleScannerLoader;
 
+  /// The location of where the explicitly-built modules will be output to
+  std::string moduleOutputPath;
+  /// The location of where the explicitly-built SDK modules will be output to
+  std::string sdkModuleOutputPath;
+
+  // CAS instance.
+  std::shared_ptr<llvm::cas::ObjectStore> CAS;
+  std::shared_ptr<llvm::cas::ActionCache> ActionCache;
+  /// File prefix mapper.
+  std::shared_ptr<llvm::PrefixMapper> PrefixMapper;
+
   // Base command line invocation for clang scanner queries (both module and header)
   std::vector<std::string> clangScanningBaseCommandLineArgs;
   // Command line invocation for clang by-name module lookups
@@ -98,15 +108,6 @@ class ModuleDependencyScanningWorker {
   std::vector<std::string> swiftModuleClangCC1CommandLineArgs;
   // Working directory for clang module lookup queries
   std::string clangScanningWorkingDirectoryPath;
-
-  /// The location of where the explicitly-built modules will be output to
-  std::string moduleOutputPath;
-  /// The location of where the explicitly-built SDK modules will be output to
-  std::string sdkModuleOutputPath;
-
-  // CAS instance.
-  std::shared_ptr<llvm::cas::ObjectStore> CAS;
-  std::shared_ptr<llvm::cas::ActionCache> ActionCache;
   // Restrict access to the parent scanner class.
   friend class ModuleDependencyScanner;
 };
@@ -221,6 +222,8 @@ class ModuleDependencyScanner {
   unsigned NumThreads;
   std::list<std::unique_ptr<ModuleDependencyScanningWorker>> Workers;
   llvm::DefaultThreadPool ScanningThreadPool;
+  /// File prefix mapper.
+  std::shared_ptr<llvm::PrefixMapper> PrefixMapper;
   /// Protect worker access.
   std::mutex WorkersLock;
   /// Count of filesystem queries performed

include/swift/DependencyScan/ScanDependencies.h

@@ -58,13 +58,15 @@ bool prescanDependencies(CompilerInstance &instance);
 // MARK: Dependency scanning execution
 /// Scans the dependencies of the main module of \c instance.
 llvm::ErrorOr<swiftscan_dependency_graph_t>
-performModuleScan(CompilerInstance &instance,
+performModuleScan(SwiftDependencyScanningService &service,
+                  CompilerInstance &instance,
                   ModuleDependenciesCache &cache,
                   DependencyScanDiagnosticCollector *diagnostics = nullptr);
 
 /// Scans the main module of \c instance for all direct module imports
 llvm::ErrorOr<swiftscan_import_set_t>
-performModulePrescan(CompilerInstance &instance,
+performModulePrescan(SwiftDependencyScanningService &service,
+                     CompilerInstance &instance,
                      ModuleDependenciesCache &cache,
                      DependencyScanDiagnosticCollector *diagnostics = nullptr);
 
@@ -75,6 +77,7 @@ namespace incremental {
 /// than the serialized dependency graph, it is considered invalidated and must
 /// be re-scanned.
 void validateInterModuleDependenciesCache(
+    const SwiftDependencyScanningService &service,
     const ModuleDependencyID &rootModuleID, ModuleDependenciesCache &cache,
     const llvm::sys::TimePoint<> &cacheTimeStamp, llvm::vfs::FileSystem &fs,
     DiagnosticEngine &diags, bool emitRemarks = false);
@@ -83,7 +86,8 @@ void validateInterModuleDependenciesCache(
 /// with respect to their inputs. Upon encountering such a module, add it to the
 /// set of invalidated modules, along with the path from the root to this
 /// module.
-void outOfDateModuleScan(const ModuleDependencyID &sourceModuleID,
+void outOfDateModuleScan(const SwiftDependencyScanningService &service,
+                         const ModuleDependencyID &sourceModuleID,
                          const ModuleDependenciesCache &cache,
                          const llvm::sys::TimePoint<> &cacheTimeStamp,
                          llvm::vfs::FileSystem &fs, DiagnosticEngine &diags,
@@ -93,6 +97,7 @@ void outOfDateModuleScan(const ModuleDependencyID &sourceModuleID,
 /// Validate whether all inputs of a given module dependency
 /// are older than the cache serialization time.
 bool verifyModuleDependencyUpToDate(
+    const SwiftDependencyScanningService &service,
     const ModuleDependencyID &moduleID, const ModuleDependenciesCache &cache,
     const llvm::sys::TimePoint<> &cacheTimeStamp, llvm::vfs::FileSystem &fs,
     DiagnosticEngine &diags, bool emitRemarks);

lib/AST/ModuleDependencies.cpp

@@ -781,10 +781,8 @@ bool SwiftDependencyScanningService::setupCachingDependencyScanningService(
 }
 
 ModuleDependenciesCache::ModuleDependenciesCache(
-    SwiftDependencyScanningService &globalScanningService,
     const std::string &mainScanModuleName, const std::string &scannerContextHash)
-    : globalScanningService(globalScanningService),
-      mainScanModuleName(mainScanModuleName),
+    : mainScanModuleName(mainScanModuleName),
       scannerContextHash(scannerContextHash),
       scanInitializationTime(std::chrono::system_clock::now()) {
   for (auto kind = ModuleDependencyKind::FirstKind;

lib/ClangImporter/ClangModuleDependencyScanner.cpp

@@ -85,7 +85,6 @@ ModuleDependencyVector ClangImporter::bridgeClangModuleDependencies(
     const ASTContext &ctx,
     clang::tooling::dependencies::DependencyScanningTool &clangScanningTool,
     clang::tooling::dependencies::ModuleDepsGraph &clangDependencies,
-    StringRef moduleOutputPath, StringRef stableModuleOutputPath,
     LookupModuleOutputCallback lookupModuleOutput,
     RemapPathCallback callback) {
   ModuleDependencyVector result;

lib/DependencyScan/DependencyScanningTool.cpp

@@ -288,10 +288,11 @@ DependencyScanningTool::getDependencies(
 
   // Local scan cache instance, wrapping the shared global cache.
   ModuleDependenciesCache cache(
-      *ScanningService, QueryContext.ScanInstance->getMainModule()->getNameStr().str(),
+      QueryContext.ScanInstance->getMainModule()->getNameStr().str(),
       QueryContext.ScanInstance->getInvocation().getModuleScanningHash());
   // Execute the scanning action, retrieving the in-memory result
-  auto DependenciesOrErr = performModuleScan(*QueryContext.ScanInstance.get(),
+  auto DependenciesOrErr = performModuleScan(*ScanningService,
+                                             *QueryContext.ScanInstance.get(),
                                              cache,
                                              QueryContext.ScanDiagnostics.get());
   if (DependenciesOrErr.getError())
@@ -317,9 +318,10 @@ DependencyScanningTool::getImports(ArrayRef<const char *> Command,
 
   // Local scan cache instance, wrapping the shared global cache.
   ModuleDependenciesCache cache(
-      *ScanningService, QueryContext.ScanInstance->getMainModule()->getNameStr().str(),
+      QueryContext.ScanInstance->getMainModule()->getNameStr().str(),
       QueryContext.ScanInstance->getInvocation().getModuleScanningHash());
-  auto DependenciesOrErr = performModulePrescan(*QueryContext.ScanInstance.get(), 
+  auto DependenciesOrErr = performModulePrescan(*ScanningService,
+                                                *QueryContext.ScanInstance.get(),
                                                 cache,
                                                 QueryContext.ScanDiagnostics.get());
   if (DependenciesOrErr.getError())