Do dynamic layout of generic/resilient default actors properly.

Since these types have an implicit stored property, this requires
adding an abstraction over fields to IRGen, at least throughout
the class code.  In some ways I think this significantly improves
the code, especially in how we approach missing members.

Fixes rdar://72202671.

Author: rjmccall

docs/ABI/Mangling.rst

@@ -493,6 +493,7 @@ Types
   type ::= 'Bb'                              // Builtin.BridgeObject
   type ::= 'BB'                              // Builtin.UnsafeValueBuffer
   type ::= 'Bc'                              // Builtin.RawUnsafeContinuation
+  type ::= 'BD'                              // Builtin.DefaultActorStorage
   type ::= 'Bf' NATURAL '_'                  // Builtin.Float<n>
   type ::= 'Bi' NATURAL '_'                  // Builtin.Int<n>
   type ::= 'BI'                              // Builtin.IntLiteral

include/swift/AST/TypeNodes.def

@@ -110,6 +110,7 @@ ABSTRACT_TYPE(Builtin, Type)
   BUILTIN_TYPE(BuiltinNativeObject, BuiltinType)
   BUILTIN_TYPE(BuiltinBridgeObject, BuiltinType)
   BUILTIN_TYPE(BuiltinUnsafeValueBuffer, BuiltinType)
+  BUILTIN_TYPE(BuiltinDefaultActorStorage, BuiltinType)
   BUILTIN_TYPE(BuiltinVector, BuiltinType)
   TYPE_RANGE(Builtin, BuiltinInteger, BuiltinVector)
 TYPE(Tuple, Type)
@@ -185,6 +186,7 @@ SINGLETON_TYPE(RawUnsafeContinuation, BuiltinRawUnsafeContinuation)
 SINGLETON_TYPE(NativeObject, BuiltinNativeObject)
 SINGLETON_TYPE(BridgeObject, BuiltinBridgeObject)
 SINGLETON_TYPE(UnsafeValueBuffer, BuiltinUnsafeValueBuffer)
+SINGLETON_TYPE(DefaultActorStorage, BuiltinDefaultActorStorage)
 SINGLETON_TYPE(SILToken, SILToken)
 #undef SINGLETON_TYPE
 #endif

include/swift/AST/Types.h

@@ -1420,6 +1420,22 @@ class BuiltinJobType : public BuiltinType {
 };
 DEFINE_EMPTY_CAN_TYPE_WRAPPER(BuiltinJobType, BuiltinType);
 
+/// BuiltinDefaultActorStorageType - The type of the stored property
+/// that's added implicitly to default actors.  No C equivalent because
+/// the C types all include a heap-object header.  Similarly, this type
+/// generally does not appear in the AST/SIL around default actors;
+/// it's purely a convenience in IRGen.
+class BuiltinDefaultActorStorageType : public BuiltinType {
+  friend class ASTContext;
+  BuiltinDefaultActorStorageType(const ASTContext &C)
+    : BuiltinType(TypeKind::BuiltinDefaultActorStorage, C) {}
+public:
+  static bool classof(const TypeBase *T) {
+    return T->getKind() == TypeKind::BuiltinDefaultActorStorage;
+  }
+};
+DEFINE_EMPTY_CAN_TYPE_WRAPPER(BuiltinDefaultActorStorageType, BuiltinType);
+
 /// BuiltinNativeObjectType - The builtin opaque object-pointer type.
 /// Useful for keeping an object alive when it is otherwise being
 /// manipulated via an unsafe pointer type.

include/swift/Reflection/Records.h

@@ -37,6 +37,9 @@ class FieldRecordFlags {
 
     // Is this a mutable `var` property?
     IsVar = 0x2,
+
+    // Is this an artificial field?
+    IsArtificial = 0x4,
   };
   int_type Data = 0;
 
@@ -49,6 +52,10 @@ class FieldRecordFlags {
     return (Data & IsVar) == IsVar;
   }
 
+  bool isArtificial() const {
+    return (Data & IsArtificial) == IsArtificial;
+  }
+
   void setIsIndirectCase(bool IndirectCase=true) {
     if (IndirectCase)
       Data |= IsIndirectCase;
@@ -63,6 +70,13 @@ class FieldRecordFlags {
       Data &= ~IsVar;
   }
 
+  void setIsArtificial(bool artificial=true) {
+    if (artificial)
+      Data |= IsArtificial;
+    else
+      Data &= ~IsArtificial;
+  }
+
   int_type getRawValue() const {
     return Data;
   }

include/swift/Strings.h

@@ -47,6 +47,9 @@ constexpr static const StringLiteral CXX_TEMPLATE_INST_PREFIX =
 constexpr static const StringLiteral SEMANTICS_PROGRAMTERMINATION_POINT =
     "programtermination_point";
 
+constexpr static const StringLiteral DEFAULT_ACTOR_STORAGE_FIELD_NAME =
+    "$defaultActor";
+
 /// The name of the Builtin type prefix
 constexpr static const StringLiteral BUILTIN_TYPE_NAME_PREFIX = "Builtin.";
 
@@ -119,6 +122,9 @@ constexpr static BuiltinNameStringLiteral BUILTIN_TYPE_NAME_UNSAFEVALUEBUFFER =
 /// The name of the Builtin type for Job
 constexpr static BuiltinNameStringLiteral BUILTIN_TYPE_NAME_JOB = {
     "Builtin.Job"};
+/// The name of the Builtin type for DefaultActorStorage
+constexpr static BuiltinNameStringLiteral BUILTIN_TYPE_NAME_DEFAULTACTORSTORAGE = {
+    "Builtin.DefaultActorStorage"};
 /// The name of the Builtin type for UnknownObject
 ///
 /// This no longer exists as an AST-accessible type, but it's still used for

lib/AST/ASTDumper.cpp

@@ -3561,6 +3561,7 @@ namespace {
 
     TRIVIAL_TYPE_PRINTER(BuiltinIntegerLiteral, builtin_integer_literal)
     TRIVIAL_TYPE_PRINTER(BuiltinJob, builtin_job)
+    TRIVIAL_TYPE_PRINTER(BuiltinDefaultActorStorage, builtin_default_actor_storage)
     TRIVIAL_TYPE_PRINTER(BuiltinRawPointer, builtin_raw_pointer)
     TRIVIAL_TYPE_PRINTER(BuiltinRawUnsafeContinuation, builtin_raw_unsafe_continuation)
     TRIVIAL_TYPE_PRINTER(BuiltinNativeObject, builtin_native_object)

lib/AST/ASTMangler.cpp

@@ -975,6 +975,8 @@ void ASTMangler::appendType(Type type, const ValueDecl *forDecl) {
       return appendOperator("BI");
     case TypeKind::BuiltinJob:
       return appendOperator("Bj");
+    case TypeKind::BuiltinDefaultActorStorage:
+      return appendOperator("BD");
     case TypeKind::BuiltinRawPointer:
       return appendOperator("Bp");
     case TypeKind::BuiltinRawUnsafeContinuation:

lib/AST/ASTPrinter.cpp

@@ -3940,6 +3940,7 @@ class TypePrinter : public TypeVisitor<TypePrinter> {
   ASTPRINTER_PRINT_BUILTINTYPE(BuiltinRawPointerType)
   ASTPRINTER_PRINT_BUILTINTYPE(BuiltinRawUnsafeContinuationType)
   ASTPRINTER_PRINT_BUILTINTYPE(BuiltinJobType)
+  ASTPRINTER_PRINT_BUILTINTYPE(BuiltinDefaultActorStorageType)
   ASTPRINTER_PRINT_BUILTINTYPE(BuiltinNativeObjectType)
   ASTPRINTER_PRINT_BUILTINTYPE(BuiltinBridgeObjectType)
   ASTPRINTER_PRINT_BUILTINTYPE(BuiltinUnsafeValueBufferType)

lib/AST/Builtins.cpp

@@ -83,6 +83,8 @@ Type swift::getBuiltinType(ASTContext &Context, StringRef Name) {
     return Context.TheRawUnsafeContinuationType;
   if (Name == "Job")
     return Context.TheJobType;
+  if (Name == "DefaultActorStorage")
+    return Context.TheDefaultActorStorageType;
   if (Name == "NativeObject")
     return Context.TheNativeObjectType;
   if (Name == "BridgeObject")
@@ -2733,6 +2735,9 @@ StringRef BuiltinType::getTypeName(SmallVectorImpl<char> &result,
   case BuiltinTypeKind::BuiltinJob:
     printer << MAYBE_GET_NAMESPACED_BUILTIN(BUILTIN_TYPE_NAME_JOB);
     break;
+  case BuiltinTypeKind::BuiltinDefaultActorStorage:
+    printer << MAYBE_GET_NAMESPACED_BUILTIN(BUILTIN_TYPE_NAME_DEFAULTACTORSTORAGE);
+    break;
   case BuiltinTypeKind::BuiltinNativeObject:
     printer << MAYBE_GET_NAMESPACED_BUILTIN(BUILTIN_TYPE_NAME_NATIVEOBJECT);
     break;

lib/AST/Type.cpp

@@ -210,6 +210,7 @@ bool CanType::isReferenceTypeImpl(CanType type, const GenericSignatureImpl *sig,
   case TypeKind::BuiltinRawPointer:
   case TypeKind::BuiltinRawUnsafeContinuation:
   case TypeKind::BuiltinJob:
+  case TypeKind::BuiltinDefaultActorStorage:
   case TypeKind::BuiltinUnsafeValueBuffer:
   case TypeKind::BuiltinVector:
   case TypeKind::Tuple:
@@ -5007,6 +5008,7 @@ ReferenceCounting TypeBase::getReferenceCounting() {
   case TypeKind::BuiltinRawPointer:
   case TypeKind::BuiltinRawUnsafeContinuation:
   case TypeKind::BuiltinJob:
+  case TypeKind::BuiltinDefaultActorStorage:
   case TypeKind::BuiltinUnsafeValueBuffer:
   case TypeKind::BuiltinVector:
   case TypeKind::Tuple: