[Serialization] ProtocolLayout: Serialize inherited protocols instead of types

Author: xedin

lib/Serialization/DeclTypeRecordNodes.def

@@ -214,6 +214,8 @@ TRAILING_INFO(CONDITIONAL_SUBSTITUTION_COND)
 
 OTHER(LIFETIME_DEPENDENCE, 158)
 
+TRAILING_INFO(INHERITED_PROTOCOLS)
+
 #ifndef DECL_ATTR
 #define DECL_ATTR(NAME, CLASS, OPTIONS, CODE) RECORD_VAL(CLASS##_DECL_ATTR, 180+CODE)
 #endif

lib/Serialization/Deserialization.cpp

@@ -1717,6 +1717,35 @@ ModuleFile::getSubstitutionMapChecked(serialization::SubstitutionMapID id) {
   return substitutions;
 }
 
+bool ModuleFile::readInheritedProtocols(
+    SmallVectorImpl<ProtocolDecl *> &inherited) {
+  using namespace decls_block;
+
+  BCOffsetRAII lastRecordOffset(DeclTypeCursor);
+
+  llvm::BitstreamEntry entry =
+      fatalIfUnexpected(DeclTypeCursor.advance(AF_DontPopBlockAtEnd));
+  if (entry.Kind != llvm::BitstreamEntry::Record)
+    return false;
+
+  SmallVector<uint64_t, 8> scratch;
+  unsigned recordID =
+      fatalIfUnexpected(DeclTypeCursor.readRecord(entry.ID, scratch));
+  if (recordID != INHERITED_PROTOCOLS)
+    return false;
+
+  lastRecordOffset.reset();
+
+  ArrayRef<uint64_t> inheritedIDs;
+  InheritedProtocolsLayout::readRecord(scratch, inheritedIDs);
+
+  llvm::transform(inheritedIDs, std::back_inserter(inherited),
+                  [&](uint64_t protocolID) {
+                    return cast<ProtocolDecl>(getDecl(protocolID));
+                  });
+  return true;
+}
+
 bool ModuleFile::readDefaultWitnessTable(ProtocolDecl *proto) {
   using namespace decls_block;
 
@@ -4425,21 +4454,19 @@ class DeclDeserializer {
     bool isImplicit, isClassBounded, isObjC, hasSelfOrAssocTypeRequirements;
     TypeID superclassID;
     uint8_t rawAccessLevel;
-    unsigned numInheritedTypes;
-    ArrayRef<uint64_t> rawInheritedAndDependencyIDs;
+    ArrayRef<uint64_t> dependencyIDs;
 
     decls_block::ProtocolLayout::readRecord(scratch, nameID, contextID,
                                             isImplicit, isClassBounded, isObjC,
                                             hasSelfOrAssocTypeRequirements,
                                             superclassID,
-                                            rawAccessLevel, numInheritedTypes,
-                                            rawInheritedAndDependencyIDs);
+                                            rawAccessLevel,
+                                            dependencyIDs);
 
     Identifier name = MF.getIdentifier(nameID);
     PrettySupplementalDeclNameTrace trace(name);
 
-    for (TypeID dependencyID :
-           rawInheritedAndDependencyIDs.slice(numInheritedTypes)) {
+    for (TypeID dependencyID : dependencyIDs) {
       auto dependency = MF.getTypeChecked(dependencyID);
       if (!dependency) {
         return llvm::make_error<TypeError>(
@@ -4469,14 +4496,17 @@ class DeclDeserializer {
     else
       return MF.diagnoseFatal();
 
+    SmallVector<ProtocolDecl *, 2> inherited;
+    if (!MF.readInheritedProtocols(inherited))
+      return MF.diagnoseFatal();
+    ctx.evaluator.cacheOutput(InheritedProtocolsRequest{proto},
+                              ctx.AllocateCopy(inherited));
+
     auto genericParams = MF.maybeReadGenericParams(DC);
     assert(genericParams && "protocol with no generic parameters?");
     ctx.evaluator.cacheOutput(GenericParamListRequest{proto},
                               std::move(genericParams));
 
-    handleInherited(proto,
-                    rawInheritedAndDependencyIDs.slice(0, numInheritedTypes));
-
     if (isImplicit)
       proto->setImplicit();
     proto->setIsObjC(isObjC);

lib/Serialization/ModuleFile.h

@@ -538,6 +538,9 @@ class ModuleFile
       SmallVectorImpl<AssociatedTypeDecl *> &assocTypes,
       llvm::BitstreamCursor &Cursor);
 
+  /// Read a list of the protocol declarations inherited by another protocol.
+  bool readInheritedProtocols(SmallVectorImpl<ProtocolDecl *> &inherited);
+
   /// Populates the protocol's default witness table.
   ///
   /// Returns true if there is an error.

lib/Serialization/ModuleFormat.h

@@ -58,7 +58,7 @@ const uint16_t SWIFTMODULE_VERSION_MAJOR = 0;
 /// describe what change you made. The content of this comment isn't important;
 /// it just ensures a conflict if two people change the module format.
 /// Don't worry about adhering to the 80-column limit for this line.
-const uint16_t SWIFTMODULE_VERSION_MINOR = 857; // Add superclass to protocol layout
+const uint16_t SWIFTMODULE_VERSION_MINOR = 858; // Replace inherited types with protocols in protocol layout
 
 /// A standard hash seed used for all string hashes in a serialized module.
 ///
@@ -1529,10 +1529,16 @@ namespace decls_block {
     BCFixed<1>,             // existential-type-supported?
     TypeIDField,            // superclass
     AccessLevelField,       // access level
-    BCVBR<4>,               // number of inherited types
-    BCArray<TypeIDField>    // inherited types, followed by dependency types
-    // Trailed by the generic parameters (if any), the members record, and
-    // the default witness table record
+    BCArray<TypeIDField>    // dependency types
+    // Trailed by the inherited protocols, the generic parameters (if any),
+    // the generic signature, the members record, and the default witness table record
+  >;
+
+  /// A default witness table for a protocol.
+  using InheritedProtocolsLayout = BCRecordLayout<
+    INHERITED_PROTOCOLS,
+    BCArray<DeclIDField>
+    // An array of inherited protocol declarations
   >;
 
   /// A default witness table for a protocol.

lib/Serialization/Serialization.cpp

@@ -3712,6 +3712,18 @@ class Serializer::DeclSerializer : public DeclVisitor<DeclSerializer> {
     }
   }
 
+  void writeInheritedProtocols(ArrayRef<ProtocolDecl *> inherited) {
+    using namespace decls_block;
+
+    SmallVector<DeclID, 4> inheritedIDs;
+    llvm::transform(inherited, std::back_inserter(inheritedIDs),
+                    [&](const ProtocolDecl *P) { return S.addDeclRef(P); });
+
+    unsigned abbrCode = S.DeclTypeAbbrCodes[InheritedProtocolsLayout::Code];
+    InheritedProtocolsLayout::emitRecord(S.Out, S.ScratchRecord, abbrCode,
+                                         inheritedIDs);
+  }
+
   void writeDefaultWitnessTable(const ProtocolDecl *proto) {
     using namespace decls_block;
 
@@ -4280,12 +4292,8 @@ class Serializer::DeclSerializer : public DeclVisitor<DeclSerializer> {
 
     auto contextID = S.addDeclContextRef(proto->getDeclContext());
 
-    SmallVector<TypeID, 4> inheritedAndDependencyTypes;
     swift::SmallSetVector<Type, 4> dependencyTypes;
 
-    unsigned numInherited = addInherited(
-        proto->getInherited(), inheritedAndDependencyTypes);
-
     // Separately collect inherited protocol types as dependencies.
     for (auto element : proto->getInherited().getEntries()) {
       auto elementType = element.getType();
@@ -4311,8 +4319,9 @@ class Serializer::DeclSerializer : public DeclVisitor<DeclSerializer> {
                                   /*excluding*/S.M);
     }
 
+    SmallVector<TypeID, 4> dependencyTypeIDs;
     for (Type ty : dependencyTypes)
-      inheritedAndDependencyTypes.push_back(S.addTypeRef(ty));
+      dependencyTypeIDs.push_back(S.addTypeRef(ty));
 
     uint8_t rawAccessLevel = getRawStableAccessLevel(proto->getFormalAccess());
 
@@ -4326,9 +4335,10 @@ class Serializer::DeclSerializer : public DeclVisitor<DeclSerializer> {
                                proto->isObjC(),
                                proto->hasSelfOrAssociatedTypeRequirements(),
                                S.addTypeRef(proto->getSuperclass()),
-                               rawAccessLevel, numInherited,
-                               inheritedAndDependencyTypes);
+                               rawAccessLevel,
+                               dependencyTypeIDs);
 
+    writeInheritedProtocols(proto->getInheritedProtocols());
     writeGenericParams(proto->getGenericParams());
     S.writeRequirementSignature(proto->getRequirementSignature());
     S.writeAssociatedTypes(proto->getAssociatedTypeMembers());
@@ -6032,6 +6042,8 @@ void Serializer::writeAllDeclsAndTypes() {
   registerDeclTypeAbbr<ConditionalSubstitutionLayout>();
   registerDeclTypeAbbr<ConditionalSubstitutionConditionLayout>();
 
+  registerDeclTypeAbbr<InheritedProtocolsLayout>();
+
 #define DECL_ATTR(X, NAME, ...) \
   registerDeclTypeAbbr<NAME##DeclAttrLayout>();
 #include "swift/AST/DeclAttr.def"