ASTGen: An assortment of strides and improvements

include/swift/AST/ASTContext.h

@@ -1347,11 +1347,14 @@ class ASTContext final {
   getInheritedConformance(Type type, ProtocolConformance *inherited);
 
   /// Get the lazy data for the given declaration.
+  LazyContextData *getLazyContextData(const Decl *decl) const;
+
+  /// Get or otherwise allocate the lazy data for the given declaration.
   ///
   /// \param lazyLoader If non-null, the lazy loader to use when creating the
   /// lazy data. The pointer must either be null or be consistent
-  /// across all calls for the same \p func.
-  LazyContextData *getOrCreateLazyContextData(const DeclContext *decl,
+  /// across all calls for the same \p decl.
+  LazyContextData *getOrCreateLazyContextData(const Decl *decl,
                                               LazyMemberLoader *lazyLoader);
 
   /// Get the lazy iterable context for the given iterable declaration context.

include/swift/AST/Decl.h

@@ -548,6 +548,11 @@ class alignas(1 << DeclAlignInBits) Decl : public ASTAllocated<Decl> {
     IsOpaqueType : 1
   );
 
+  SWIFT_INLINE_BITFIELD_FULL(AssociatedTypeDecl, TypeDecl, 1,
+    /// Whether we have computed the default type.
+    IsDefaultDefinitionTypeComputed : 1
+  );
+
   SWIFT_INLINE_BITFIELD_EMPTY(GenericTypeDecl, TypeDecl);
 
   SWIFT_INLINE_BITFIELD(TypeAliasDecl, GenericTypeDecl, 1+1,
@@ -3677,24 +3682,28 @@ class AssociatedTypeDecl : public TypeDecl {
   SourceLoc KeywordLoc;
 
   /// The default definition.
-  TypeRepr *DefaultDefinition;
+  TypeLoc DefaultDefinition;
 
   /// The where clause attached to the associated type.
   TrailingWhereClause *TrailingWhere;
 
-  LazyMemberLoader *Resolver = nullptr;
-  uint64_t ResolverContextData;
-
   friend class DefaultDefinitionTypeRequest;
 
-public:
   AssociatedTypeDecl(DeclContext *dc, SourceLoc keywordLoc, Identifier name,
                      SourceLoc nameLoc, TypeRepr *defaultDefinition,
                      TrailingWhereClause *trailingWhere);
-  AssociatedTypeDecl(DeclContext *dc, SourceLoc keywordLoc, Identifier name,
-                     SourceLoc nameLoc, TrailingWhereClause *trailingWhere,
-                     LazyMemberLoader *definitionResolver,
-                     uint64_t resolverData);
+
+public:
+  static AssociatedTypeDecl *createParsed(ASTContext &ctx, DeclContext *dc,
+                                          SourceLoc keywordLoc, Identifier name,
+                                          SourceLoc nameLoc,
+                                          TypeRepr *defaultDefinition,
+                                          TrailingWhereClause *trailingWhere);
+
+  static AssociatedTypeDecl *createDeserialized(
+      ASTContext &ctx, DeclContext *dc, SourceLoc keywordLoc, Identifier name,
+      SourceLoc nameLoc, TrailingWhereClause *trailingWhere,
+      LazyMemberLoader *lazyLoader, uint64_t defaultDefinitionTypeData);
 
   /// Get the protocol in which this associated type is declared.
   ProtocolDecl *getProtocol() const {
@@ -3705,15 +3714,25 @@ class AssociatedTypeDecl : public TypeDecl {
   bool hasDefaultDefinitionType() const {
     // If we have a TypeRepr, return true immediately without kicking off
     // a request.
-    return DefaultDefinition || getDefaultDefinitionType();
+    return DefaultDefinition.getTypeRepr() || getDefaultDefinitionType();
   }
 
   /// Retrieve the default definition type.
   Type getDefaultDefinitionType() const;
 
+  /// Retrieve the default definition type if computed, `None` otherwise.
+  ///
+  /// \Note Should only be used for dumping.
+  llvm::Optional<Type> getCachedDefaultDefinitionType() const;
+
+private:
+  /// Set the computed default definition type.
+  void setDefaultDefinitionType(Type ty);
+
+public:
   /// Retrieve the default definition as written in the source.
   TypeRepr *getDefaultDefinitionTypeRepr() const {
-    return DefaultDefinition;
+    return DefaultDefinition.getTypeRepr();
   }
 
   /// Retrieve the trailing where clause for this associated type, if any.

include/swift/AST/DefaultArgumentKind.h

@@ -54,6 +54,11 @@ enum class DefaultArgumentKind : uint8_t {
 };
 enum { NumDefaultArgumentKindBits = 4 };
 
+/// Determine the kind of a default argument given a parsed expression that has
+/// not yet been type-checked.
+/// FIXME: Requestify/internalize the computation of the default arg expr and its kind (given a parsed expr) once the old parser no longer needs this.
+DefaultArgumentKind getDefaultArgKind(Expr *init);
+
 struct ArgumentAttrs {
   DefaultArgumentKind argumentKind;
   bool isUnavailableInSwift = false;

include/swift/AST/LazyResolver.h

@@ -57,6 +57,12 @@ class LazyIterableDeclContextData : public LazyContextData {
   uint64_t allConformancesData = 0;
 };
 
+class LazyAssociatedTypeData : public LazyContextData {
+public:
+  /// The context data used for loading the default type.
+  uint64_t defaultDefinitionTypeData = 0;
+};
+
 /// Context data for protocols.
 class LazyProtocolData : public LazyIterableDeclContextData {
 public:

include/swift/AST/TypeCheckRequests.h

@@ -528,10 +528,10 @@ class RequirementSignatureRequest :
 };
 
 /// Compute the default definition type of an associated type.
-class DefaultDefinitionTypeRequest :
-    public SimpleRequest<DefaultDefinitionTypeRequest,
-                         Type(AssociatedTypeDecl *),
-                         RequestFlags::Cached> {
+class DefaultDefinitionTypeRequest
+    : public SimpleRequest<DefaultDefinitionTypeRequest,
+                           Type(AssociatedTypeDecl *),
+                           RequestFlags::SeparatelyCached> {
 public:
   using SimpleRequest::SimpleRequest;
 
@@ -544,6 +544,8 @@ class DefaultDefinitionTypeRequest :
 public:
   // Caching.
   bool isCached() const { return true; }
+  llvm::Optional<Type> getCachedResult() const;
+  void cacheResult(Type value) const;
 };
 
 /// Describes the owner of a where clause, from which we can extract

lib/AST/ASTContext.cpp

@@ -341,7 +341,7 @@ struct ASTContext::Implementation {
     DelayedMissingWitnesses;
 
   /// Stores information about lazy deserialization of various declarations.
-  llvm::DenseMap<const DeclContext *, LazyContextData *> LazyContexts;
+  llvm::DenseMap<const Decl *, LazyContextData *> LazyContexts;
 
   /// A fake generic parameter list <Self> for parsing @opened archetypes
   /// in textual SIL.
@@ -2829,23 +2829,30 @@ PackConformance *PackConformance::get(PackType *conformingType,
   return result;
 }
 
-LazyContextData *ASTContext::getOrCreateLazyContextData(
-                                                const DeclContext *dc,
-                                                LazyMemberLoader *lazyLoader) {
-  LazyContextData *&entry = getImpl().LazyContexts[dc];
-  if (entry) {
+LazyContextData *ASTContext::getLazyContextData(const Decl *decl) const {
+  return getImpl().LazyContexts.lookup(decl);
+}
+
+LazyContextData *
+ASTContext::getOrCreateLazyContextData(const Decl *decl,
+                                       LazyMemberLoader *lazyLoader) {
+  if (auto *data = getLazyContextData(decl)) {
     // Make sure we didn't provide an incompatible lazy loader.
-    assert(!lazyLoader || lazyLoader == entry->loader);
-    return entry;
+    assert(!lazyLoader || lazyLoader == data->loader);
+    return data;
   }
 
+  LazyContextData *&entry = getImpl().LazyContexts[decl];
+
   // Create new lazy context data with the given loader.
   assert(lazyLoader && "Queried lazy data for non-lazy iterable context");
-  if (isa<ProtocolDecl>(dc))
+  if (isa<ProtocolDecl>(decl)) {
     entry = Allocate<LazyProtocolData>();
-  else {
-    assert(isa<NominalTypeDecl>(dc) || isa<ExtensionDecl>(dc));
+  } else if (isa<NominalTypeDecl>(decl) || isa<ExtensionDecl>(decl)) {
     entry = Allocate<LazyIterableDeclContextData>();
+  } else {
+    assert(isa<AssociatedTypeDecl>(decl));
+    entry = Allocate<LazyAssociatedTypeData>();
   }
 
   entry->loader = lazyLoader;

lib/AST/ASTDumper.cpp

@@ -1110,9 +1110,14 @@ namespace {
 
     void visitAssociatedTypeDecl(AssociatedTypeDecl *decl, StringRef label) {
       printCommon(decl, "associated_type_decl", label);
-      if (auto defaultDef = decl->getDefaultDefinitionType()) {
-        printFieldQuoted(defaultDef, "default");
+
+      StringRef fieldName("default");
+      if (auto defaultDef = decl->getCachedDefaultDefinitionType()) {
+        printFieldQuoted(*defaultDef, fieldName);
+      } else {
+        printField("<not computed>", fieldName);
       }
+
       printWhereRequirements(decl);
       if (decl->overriddenDeclsComputed()) {
         printFieldQuotedRaw([&](raw_ostream &OS) {