ClangImporter: Delay building imported conformances until we ask for them

Author: slavapestov

lib/ClangImporter/ImportDecl.cpp

@@ -6864,30 +6864,11 @@ void SwiftDeclConverter::addObjCProtocolConformances(
 
   Impl.recordImportedProtocols(decl, protocols);
 
-  // Synthesize trivial conformances for each of the protocols.
-  SmallVector<ProtocolConformance *, 4> conformances;
-
-  auto dc = decl->getInnermostDeclContext();
-  auto &ctx = Impl.SwiftContext;
-  for (unsigned i = 0, n = protocols.size(); i != n; ++i) {
-    // FIXME: Build a superclass conformance if the superclass
-    // conforms.
-    auto conformance = ctx.getConformance(dc->getDeclaredInterfaceType(),
-                                          protocols[i], SourceLoc(), dc,
-                                          ProtocolConformanceState::Incomplete);
-    conformance->setLazyLoader(&Impl, /*context*/0);
-    conformance->setState(ProtocolConformanceState::Complete);
-    conformances.push_back(conformance);
-  }
-
-  // Set the conformances.
-  // FIXME: This could be lazier.
-  unsigned id = Impl.allocateDelayedConformance(std::move(conformances));
   if (auto nominal = dyn_cast<NominalTypeDecl>(decl)) {
-    nominal->setConformanceLoader(&Impl, id);
+    nominal->setConformanceLoader(&Impl, 0);
   } else {
     auto ext = cast<ExtensionDecl>(decl);
-    ext->setConformanceLoader(&Impl, id);
+    ext->setConformanceLoader(&Impl, 0);
   }
 }
 
@@ -8690,7 +8671,7 @@ void ClangImporter::Implementation::collectMembersToAdd(
 
   SwiftDeclConverter converter(*this, CurrentVersion);
 
-  SmallVector<ProtocolDecl *, 4> protos = takeImportedProtocols(D);
+  auto protos = getImportedProtocols(D);
   if (auto clangClass = dyn_cast<clang::ObjCInterfaceDecl>(objcContainer)) {
     auto swiftClass = cast<ClassDecl>(D);
     objcContainer = clangClass = clangClass->getDefinition();
@@ -8713,9 +8694,22 @@ void ClangImporter::Implementation::collectMembersToAdd(
 }
 
 void ClangImporter::Implementation::loadAllConformances(
-       const Decl *D, uint64_t contextData,
+       const Decl *decl, uint64_t contextData,
        SmallVectorImpl<ProtocolConformance *> &Conformances) {
-  Conformances = takeDelayedConformance(contextData);
+  auto dc = decl->getInnermostDeclContext();
+
+  // Synthesize trivial conformances for each of the protocols.
+  for (auto *protocol : getImportedProtocols(decl)) {
+    // FIXME: Build a superclass conformance if the superclass
+    // conforms.
+    auto conformance = SwiftContext.getConformance(
+        dc->getDeclaredInterfaceType(),
+        protocol, SourceLoc(), dc,
+        ProtocolConformanceState::Incomplete);
+    conformance->setLazyLoader(this, /*context*/0);
+    conformance->setState(ProtocolConformanceState::Complete);
+    Conformances.push_back(conformance);
+  }
 }
 
 Optional<MappedTypeNameKind>

lib/ClangImporter/ImporterImpl.h

@@ -559,17 +559,9 @@ class LLVM_LIBRARY_VISIBILITY ClangImporter::Implementation
   /// Records those modules that we have looked up.
   llvm::DenseMap<Identifier, ModuleDecl *> checkedModules;
 
-  /// Mapping from delayed conformance IDs to the set of delayed
-  /// protocol conformances.
-  llvm::DenseMap<unsigned, SmallVector<ProtocolConformance *, 4>>
-    DelayedConformances;
-
-  /// The next delayed conformance ID to use with \c DelayedConformances.
-  unsigned NextDelayedConformanceID = 0;
-
   /// The set of imported protocols for a declaration, used only to
   /// load all members of the declaration.
-  llvm::DenseMap<const Decl *, SmallVector<ProtocolDecl *, 4>>
+  llvm::DenseMap<const Decl *, ArrayRef<ProtocolDecl *>>
     ImportedProtocols;
 
   void startedImportingEntity();
@@ -1179,24 +1171,6 @@ class LLVM_LIBRARY_VISIBILITY ClangImporter::Implementation
   /// 'let' declaration as opposed to 'var'.
   bool shouldImportGlobalAsLet(clang::QualType type);
 
-  /// Allocate a new delayed conformance ID with the given set of
-  /// conformances.
-  unsigned allocateDelayedConformance(
-             SmallVector<ProtocolConformance *, 4> &&conformances) {
-    unsigned id = NextDelayedConformanceID++;
-    DelayedConformances[id] = std::move(conformances);
-    return id;
-  }
-
-  /// Take the delayed conformances associated with the given id.
-  SmallVector<ProtocolConformance *, 4> takeDelayedConformance(unsigned id) {
-    auto conformances = DelayedConformances.find(id);
-    SmallVector<ProtocolConformance *, 4> result
-      = std::move(conformances->second);
-    DelayedConformances.erase(conformances);
-    return result;
-  }
-
   /// Record the set of imported protocols for the given declaration,
   /// to be used by member loading.
   ///
@@ -1207,21 +1181,15 @@ class LLVM_LIBRARY_VISIBILITY ClangImporter::Implementation
     if (protocols.empty())
       return;
 
-    auto &recorded = ImportedProtocols[decl];
-    recorded.insert(recorded.end(), protocols.begin(), protocols.end());
+    ImportedProtocols[decl] = SwiftContext.AllocateCopy(protocols);
   }
 
   /// Retrieve the imported protocols for the given declaration.
-  SmallVector<ProtocolDecl *, 4> takeImportedProtocols(const Decl *decl) {
-    SmallVector<ProtocolDecl *, 4> result;
-
+  ArrayRef<ProtocolDecl *> getImportedProtocols(const Decl *decl) {
     auto known = ImportedProtocols.find(decl);
-    if (known != ImportedProtocols.end()) {
-      result = std::move(known->second);
-      ImportedProtocols.erase(known);
-    }
-
-    return result;
+    if (known != ImportedProtocols.end())
+      return known->second;
+    return ArrayRef<ProtocolDecl *>();
   }
 
   EnumDecl *lookupErrorCodeEnum(const StructDecl *errorWrapper) {