Merge pull request swiftlang#31229 from CodaFi/collect-a-mundo

[NFC] Extract Dependency Registration to DependencyCollector

Author: CodaFi

include/swift/AST/Evaluator.h

@@ -48,12 +48,6 @@ class DiagnosticEngine;
 class Evaluator;
 class UnifiedStatsReporter;
 
-namespace detail {
-// Remove this when the compiler bumps to C++17.
-template <typename...>
-using void_t = void;
-}
-
 /// An "abstract" request function pointer, which is the storage type
 /// used for each of the
 using AbstractRequestFunction = void(void);
@@ -231,37 +225,7 @@ class Evaluator {
   /// so all clients must cope with cycles.
   llvm::DenseMap<AnyRequest, std::vector<AnyRequest>> dependencies;
 
-  /// A stack of dependency sources in the order they were evaluated.
-  llvm::SmallVector<evaluator::DependencySource, 8> dependencySources;
-
-  /// An RAII type that manages manipulating the evaluator's
-  /// dependency source stack. It is specialized to be zero-cost for
-  /// requests that are not dependency sources.
-  template <typename Request, typename = detail::void_t<>>
-  struct IncrementalDependencyStackRAII {
-    IncrementalDependencyStackRAII(Evaluator &E, const Request &Req) {}
-  };
-
-  template <typename Request>
-  struct IncrementalDependencyStackRAII<
-      Request, typename std::enable_if<Request::isDependencySource>::type> {
-    NullablePtr<Evaluator> Eval;
-    IncrementalDependencyStackRAII(Evaluator &E, const Request &Req) {
-      auto Source = Req.readDependencySource(E);
-      // If there is no source to introduce, bail. This can occur if
-      // a request originates in the context of a module.
-      if (!Source.getPointer()) {
-        return;
-      }
-      E.dependencySources.emplace_back(Source);
-      Eval = &E;
-    }
-
-    ~IncrementalDependencyStackRAII() {
-      if (Eval.isNonNull())
-        Eval.get()->dependencySources.pop_back();
-    }
-  };
+  evaluator::DependencyCollector collector;
 
   /// Retrieve the request function for the given zone and request IDs.
   AbstractRequestFunction *getAbstractRequestFunction(uint8_t zoneID,
@@ -303,7 +267,8 @@ class Evaluator {
            typename std::enable_if<Request::isEverCached>::type * = nullptr>
   llvm::Expected<typename Request::OutputType>
   operator()(const Request &request) {
-    IncrementalDependencyStackRAII<Request> incDeps{*this, request};
+    evaluator::DependencyCollector::StackRAII<Request> incDeps{collector,
+                                                               request};
     // The request can be cached, but check a predicate to determine
     // whether this particular instance is cached. This allows more
     // fine-grained control over which instances get cache.
@@ -319,7 +284,8 @@ class Evaluator {
            typename std::enable_if<!Request::isEverCached>::type * = nullptr>
   llvm::Expected<typename Request::OutputType>
   operator()(const Request &request) {
-    IncrementalDependencyStackRAII<Request> incDeps{*this, request};
+    evaluator::DependencyCollector::StackRAII<Request> incDeps{collector,
+                                                               request};
     return getResultUncached(request);
   }
 
@@ -476,47 +442,7 @@ class Evaluator {
             typename std::enable_if<Request::isDependencySink>::type * = nullptr>
   void reportEvaluatedResult(const Request &r,
                              const typename Request::OutputType &o) {
-    if (auto *tracker = getActiveDependencyTracker())
-      r.writeDependencySink(*this, *tracker, o);
-  }
-
-  /// If there is an active dependency source, returns its
-  /// \c ReferencedNameTracker. Else, returns \c nullptr.
-  ReferencedNameTracker *getActiveDependencyTracker() const {
-    if (auto *source = getActiveDependencySourceOrNull())
-      return source->getRequestBasedReferencedNameTracker();
-    return nullptr;
-  }
-
-public:
-  /// Returns \c true if the scope of the current active source cascades.
-  ///
-  /// If there is no active scope, the result always cascades.
-  bool isActiveSourceCascading() const {
-    return getActiveSourceScope() == evaluator::DependencyScope::Cascading;
-  }
-
-  /// Returns the scope of the current active scope.
-  ///
-  /// If there is no active scope, the result always cascades.
-  evaluator::DependencyScope getActiveSourceScope() const {
-    if (dependencySources.empty()) {
-      return evaluator::DependencyScope::Cascading;
-    }
-    return dependencySources.back().getInt();
-  }
-
-  /// Returns the active dependency's source file, or \c nullptr if no
-  /// dependency source is active.
-  ///
-  /// The use of this accessor is strongly discouraged, as it implies that a
-  /// dependency sink is seeking to filter out names based on the files they
-  /// come from. Existing callers are being migrated to more reasonable ways
-  /// of judging the relevancy of a dependency.
-  SourceFile *getActiveDependencySourceOrNull() const {
-    if (dependencySources.empty())
-      return nullptr;
-    return dependencySources.back().getPointer();
+    r.writeDependencySink(collector, o);
   }
 
 public:

include/swift/AST/EvaluatorDependencies.h

@@ -26,6 +26,11 @@ namespace swift {
 
 namespace evaluator {
 
+namespace detail {
+// Remove this when the compiler bumps to C++17.
+template <typename...> using void_t = void;
+} // namespace detail
+
 /// The "scope" of a dependency edge tracked by the evaluator.
 ///
 /// Dependency scopes come in two flavors: cascading and private. A private
@@ -99,6 +104,123 @@ inline DependencyScope getScopeForAccessLevel(AccessLevel l) {
 // edges in the incremental dependency graph invalidate entire files instead
 // of individual contexts.
 using DependencySource = llvm::PointerIntPair<SourceFile *, 1, DependencyScope>;
+
+/// A \c DependencyCollector is an aggregator of named references discovered in a
+/// particular \c DependencyScope during the course of request evaluation.
+struct DependencyCollector {
+private:
+  /// A stack of dependency sources in the order they were evaluated.
+  llvm::SmallVector<evaluator::DependencySource, 8> dependencySources;
+
+public:
+  DependencyCollector() = default;
+
+public:
+  /// Registers a named reference from the current dependency scope to a member
+  /// defined in the given \p subject type.
+  ///
+  /// Used member constraints are typically the by-product of direct lookups,
+  /// where the name being looked up and the target of the lookup are known
+  /// up front. A used member dependency causes the file to be rebuilt if the
+  /// definition of that member changes in any way - via
+  /// deletion, addition, or mutation of a member with that same name.
+  void addUsedMember(NominalTypeDecl *subject, DeclBaseName name);
+  /// Registers a reference from the current dependency scope to a
+  /// "potential member" of the given \p subject type.
+  ///
+  /// A single potential member dependency can be thought of as many used member
+  /// dependencies - one for each current member of the subject type, but also
+  /// one for every member that will be added or removed from the type in the
+  /// future. As such, these dependencies cause rebuilds when any members are
+  /// added, removed, or changed in the \p subject type. It also indicates a
+  /// dependency on the \p subject type's existence, so deleting the \p subject
+  /// type will also cause a rebuild.
+  ///
+  /// These dependencies are most appropriate for protocol conformances,
+  /// superclass constraints, and other requirements involving entire types.
+  void addPotentialMember(NominalTypeDecl *subject);
+  /// Registers a reference from the current dependency scope to a given
+  /// top-level \p name.
+  ///
+  /// A top level dependency causes a rebuild when another top-level entity with
+  /// that name is added, removed, or modified.
+  void addTopLevelName(DeclBaseName name);
+  /// Registers a reference from the current dependency scope to a given
+  /// dynamic member \p name.
+  ///
+  /// A dynamic lookup dependency is a special kind of member dependency on
+  /// a name that is found by \c AnyObject lookup.
+  void addDynamicLookupName(DeclBaseName name);
+
+public:
+  /// Returns the scope of the current active scope.
+  ///
+  /// If there is no active scope, the result always cascades.
+  evaluator::DependencyScope getActiveSourceScope() const {
+    if (dependencySources.empty()) {
+      return evaluator::DependencyScope::Cascading;
+    }
+    return dependencySources.back().getInt();
+  }
+
+  /// Returns the active dependency's source file, or \c nullptr if no
+  /// dependency source is active.
+  ///
+  /// The use of this accessor is strongly discouraged, as it implies that a
+  /// dependency sink is seeking to filter out names based on the files they
+  /// come from. Existing callers are being migrated to more reasonable ways
+  /// of judging the relevancy of a dependency.
+  SourceFile *getActiveDependencySourceOrNull() const {
+    if (dependencySources.empty())
+      return nullptr;
+    return dependencySources.back().getPointer();
+  }
+
+public:
+  /// An RAII type that manages manipulating the evaluator's
+  /// dependency source stack. It is specialized to be zero-cost for
+  /// requests that are not dependency sources.
+  template <typename Request, typename = detail::void_t<>> struct StackRAII {
+    StackRAII(DependencyCollector &DC, const Request &Req) {}
+  };
+
+  template <typename Request>
+  struct StackRAII<Request,
+                   typename std::enable_if<Request::isDependencySource>::type> {
+    NullablePtr<DependencyCollector> Coll;
+    StackRAII(DependencyCollector &coll, const Request &Req) {
+      auto Source = Req.readDependencySource(coll);
+      // If there is no source to introduce, bail. This can occur if
+      // a request originates in the context of a module.
+      if (!Source.getPointer()) {
+        return;
+      }
+      coll.dependencySources.emplace_back(Source);
+      Coll = &coll;
+    }
+
+    ~StackRAII() {
+      if (Coll.isNonNull())
+        Coll.get()->dependencySources.pop_back();
+    }
+  };
+
+private:
+  /// If there is an active dependency source, returns its
+  /// \c ReferencedNameTracker. Else, returns \c nullptr.
+  ReferencedNameTracker *getActiveDependencyTracker() const {
+    if (auto *source = getActiveDependencySourceOrNull())
+      return source->getRequestBasedReferencedNameTracker();
+    return nullptr;
+  }
+
+  /// Returns \c true if the scope of the current active source cascades.
+  ///
+  /// If there is no active scope, the result always cascades.
+  bool isActiveSourceCascading() const {
+    return getActiveSourceScope() == evaluator::DependencyScope::Cascading;
+  }
+};
 } // end namespace evaluator
 
 } // end namespace swift

include/swift/AST/IRGenRequests.h

@@ -199,7 +199,8 @@ class IRGenSourceFileRequest
 
 public:
   // Incremental dependencies.
-  evaluator::DependencySource readDependencySource(Evaluator &) const;
+  evaluator::DependencySource
+  readDependencySource(const evaluator::DependencyCollector &) const;
 };
 
 class IRGenWholeModuleRequest

include/swift/AST/NameLookupRequests.h

@@ -188,8 +188,9 @@ class InheritedProtocolsRequest
 
 public:
   // Incremental dependencies
-  evaluator::DependencySource readDependencySource(Evaluator &e) const;
-  void writeDependencySink(Evaluator &evaluator, ReferencedNameTracker &tracker,
+  evaluator::DependencySource
+  readDependencySource(const evaluator::DependencyCollector &e) const;
+  void writeDependencySink(evaluator::DependencyCollector &tracker,
                            ArrayRef<ProtocolDecl *> result) const;
 };
 
@@ -239,7 +240,7 @@ class ExtendedNominalRequest
 
 public:
   // Incremental dependencies
-  void writeDependencySink(Evaluator &evaluator, ReferencedNameTracker &tracker,
+  void writeDependencySink(evaluator::DependencyCollector &tracker,
                            NominalTypeDecl *result) const;
 };
 
@@ -328,7 +329,8 @@ class GetDestructorRequest
 
 public:
   // Incremental dependencies.
-  evaluator::DependencySource readDependencySource(Evaluator &) const;
+  evaluator::DependencySource
+  readDependencySource(const evaluator::DependencyCollector &) const;
 };
 
 class GenericParamListRequest :
@@ -431,8 +433,9 @@ class UnqualifiedLookupRequest
 
 public:
   // Incremental dependencies
-  evaluator::DependencySource readDependencySource(Evaluator &) const;
-  void writeDependencySink(Evaluator &eval, ReferencedNameTracker &tracker,
+  evaluator::DependencySource
+  readDependencySource(const evaluator::DependencyCollector &) const;
+  void writeDependencySink(evaluator::DependencyCollector &tracker,
                            LookupResult res) const;
 };
 
@@ -477,7 +480,7 @@ class AnyObjectLookupRequest
 
 public:
   // Incremental dependencies
-  void writeDependencySink(Evaluator &eval, ReferencedNameTracker &tracker,
+  void writeDependencySink(evaluator::DependencyCollector &tracker,
                            QualifiedLookupResult l) const;
 };
 
@@ -502,8 +505,9 @@ class ModuleQualifiedLookupRequest
 
 public:
   // Incremental dependencies
-  evaluator::DependencySource readDependencySource(Evaluator &) const;
-  void writeDependencySink(Evaluator &eval, ReferencedNameTracker &tracker,
+  evaluator::DependencySource
+  readDependencySource(const evaluator::DependencyCollector &) const;
+  void writeDependencySink(evaluator::DependencyCollector &tracker,
                            QualifiedLookupResult lookupResult) const;
 };
 
@@ -528,7 +532,8 @@ class QualifiedLookupRequest
 
 public:
   // Incremental dependencies.
-  evaluator::DependencySource readDependencySource(Evaluator &) const;
+  evaluator::DependencySource
+  readDependencySource(const evaluator::DependencyCollector &) const;
 };
 
 /// The input type for a direct lookup request.
@@ -580,7 +585,7 @@ class DirectLookupRequest
 
 public:
   // Incremental dependencies
-  void writeDependencySink(Evaluator &evaluator, ReferencedNameTracker &tracker,
+  void writeDependencySink(evaluator::DependencyCollector &tracker,
                            TinyPtrVector<ValueDecl *> result) const;
 };
 
@@ -665,7 +670,7 @@ class LookupOperatorRequest
 
 public:
   // Incremental dependencies
-  void writeDependencySink(Evaluator &evaluator, ReferencedNameTracker &tracker,
+  void writeDependencySink(evaluator::DependencyCollector &tracker,
                            OperatorType *o) const;
 };
 
@@ -755,7 +760,7 @@ class LookupConformanceInModuleRequest
 
 public:
   // Incremental dependencies
-  void writeDependencySink(Evaluator &evaluator, ReferencedNameTracker &tracker,
+  void writeDependencySink(evaluator::DependencyCollector &tracker,
                            ProtocolConformanceRef result) const;
 };
 

include/swift/AST/ParseRequests.h

@@ -102,7 +102,8 @@ class ParseSourceFileRequest
   void cacheResult(ArrayRef<Decl *> decls) const;
 
 public:
-  evaluator::DependencySource readDependencySource(Evaluator &) const;
+  evaluator::DependencySource
+  readDependencySource(const evaluator::DependencyCollector &) const;
 };
 
 void simple_display(llvm::raw_ostream &out,
@@ -123,7 +124,8 @@ class CodeCompletionSecondPassRequest
                 CodeCompletionCallbacksFactory *Factory) const;
 
 public:
-  evaluator::DependencySource readDependencySource(Evaluator &) const;
+  evaluator::DependencySource
+  readDependencySource(const evaluator::DependencyCollector &) const;
 };
 
 /// The zone number for the parser.

include/swift/AST/SILGenRequests.h

@@ -98,7 +98,8 @@ class SILGenSourceFileRequest :
 
 public:
   // Incremental dependencies.
-  evaluator::DependencySource readDependencySource(Evaluator &) const;
+  evaluator::DependencySource
+  readDependencySource(const evaluator::DependencyCollector &) const;
 };
 
 class SILGenWholeModuleRequest :