[metadata prespecialization] Cross-module: enums and structs.

When a generic type from a different module is not resilient within the
current module and at least one of its arguments is from the current
module, emit a non-canonical prespecialized record, and access that
metadata via a call to swift_getCanonicalSpecializedMetadata, passing in
the non-canonical record.

rdar://problem/56996727
rdar://problem/56997022

Author: nate-chandler

docs/ABI/Mangling.rst

@@ -173,6 +173,9 @@ Globals
 
   global ::= global 'MK'                 // instantiation cache associated with global
 
+  global ::= global 'MJ'                 // noncanonical specialized generic type metadata instantiation cache associated with global
+  global ::= global 'MN'                 // noncanonical specialized generic type metadata for global
+
 A direct symbol resolves directly to the address of an object.  An
 indirect symbol resolves to the address of a pointer to the object.
 They are distinct manglings to make a certain class of bugs

include/swift/Demangling/DemangleNodes.def

@@ -287,12 +287,12 @@ NODE(OpaqueTypeDescriptorAccessorVar)
 NODE(OpaqueReturnType)
 CONTEXT_NODE(OpaqueReturnTypeOf)
 
-// Added in Swift 5.3
+// Added in Swift 5.4
 NODE(CanonicalSpecializedGenericMetaclass)
 NODE(CanonicalSpecializedGenericTypeMetadataAccessFunction)
-
-// Added in Swift 5.4
 NODE(MetadataInstantiationCache)
+NODE(NoncanonicalSpecializedGenericTypeMetadata)
+NODE(NoncanonicalSpecializedGenericTypeMetadataCache)
 
 #undef CONTEXT_NODE
 #undef NODE

include/swift/IRGen/Linking.h

@@ -393,6 +393,16 @@ class LinkEntity {
     /// An access function for prespecialized type metadata.
     /// The pointer is a canonical TypeBase*.
     CanonicalSpecializedGenericTypeMetadataAccessFunction,
+
+    /// Metadata for a specialized generic type which cannot be statically
+    /// guaranteed to be canonical and so must be canonicalized.
+    /// The pointer is a canonical TypeBase*.
+    NoncanonicalSpecializedGenericTypeMetadata,
+
+    /// A cache variable for noncanonical specialized type metadata, to be 
+    /// passed to swift_getCanonicalSpecializedMetadata.
+    /// The pointer is a canonical TypeBase*.
+    NoncanonicalSpecializedGenericTypeMetadataCacheVariable,
   };
   friend struct llvm::DenseMapInfo<LinkEntity>;
 
@@ -1045,6 +1055,24 @@ class LinkEntity {
     return entity;
   }
 
+  static LinkEntity
+  forNoncanonicalSpecializedGenericTypeMetadata(CanType theType) {
+    LinkEntity entity;
+    entity.setForType(Kind::NoncanonicalSpecializedGenericTypeMetadata,
+                      theType);
+    entity.Data |= LINKENTITY_SET_FIELD(
+        MetadataAddress, unsigned(TypeMetadataAddress::FullMetadata));
+    return entity;
+  }
+
+
+  static LinkEntity
+  forNoncanonicalSpecializedGenericTypeMetadataCacheVariable(CanType theType) {
+    LinkEntity entity;
+    entity.setForType(Kind::NoncanonicalSpecializedGenericTypeMetadataCacheVariable, theType);
+    return entity;
+  }
+
   void mangle(llvm::raw_ostream &out) const;
   void mangle(SmallVectorImpl<char> &buffer) const;
   std::string mangleAsString() const;
@@ -1152,6 +1180,7 @@ class LinkEntity {
   }
   TypeMetadataAddress getMetadataAddress() const {
     assert(getKind() == Kind::TypeMetadata ||
+           getKind() == Kind::NoncanonicalSpecializedGenericTypeMetadata ||
            getKind() == Kind::ObjCResilientClassStub);
     return (TypeMetadataAddress)LINKENTITY_GET_FIELD(Data, MetadataAddress);
   }

lib/Demangling/Demangler.cpp

@@ -1911,12 +1911,14 @@ NodePointer Demangler::demangleMetatype() {
     case 'j':
       return createWithChild(Node::Kind::OpaqueTypeDescriptorAccessorKey,
                              popNode());
-    case 'K':
-      return createWithChild(Node::Kind::MetadataInstantiationCache,
-                             popNode());
+    case 'J':
+      return createWithChild(Node::Kind::NoncanonicalSpecializedGenericTypeMetadataCache, popNode());
     case 'k':
       return createWithChild(Node::Kind::OpaqueTypeDescriptorAccessorVar,
                              popNode());
+    case 'K':
+      return createWithChild(Node::Kind::MetadataInstantiationCache,
+                             popNode());
     case 'l':
       return createWithPoppedType(
                           Node::Kind::TypeMetadataSingletonInitializationCache);
@@ -1929,6 +1931,9 @@ NodePointer Demangler::demangleMetatype() {
           Node::Kind::CanonicalSpecializedGenericMetaclass);
     case 'n':
       return createWithPoppedType(Node::Kind::NominalTypeDescriptor);
+    case 'N':
+      return createWithPoppedType(
+          Node::Kind::NoncanonicalSpecializedGenericTypeMetadata);
     case 'o':
       return createWithPoppedType(Node::Kind::ClassMetadataBaseOffset);
     case 'p':

lib/Demangling/NodePrinter.cpp

@@ -549,6 +549,8 @@ class NodePrinter {
     case Node::Kind::OpaqueReturnTypeOf:
     case Node::Kind::CanonicalSpecializedGenericMetaclass:
     case Node::Kind::CanonicalSpecializedGenericTypeMetadataAccessFunction:
+    case Node::Kind::NoncanonicalSpecializedGenericTypeMetadata:
+    case Node::Kind::NoncanonicalSpecializedGenericTypeMetadataCache:
       return false;
     }
     printer_unreachable("bad node kind");
@@ -2438,6 +2440,14 @@ NodePointer NodePrinter::print(NodePointer Node, bool asPrefixContext) {
     Printer << "metadata instantiation cache for ";
     print(Node->getChild(0));
     return nullptr;
+  case Node::Kind::NoncanonicalSpecializedGenericTypeMetadata:
+    Printer << "noncanonical specialized generic type metadata for ";
+    print(Node->getChild(0));
+    return nullptr;
+  case Node::Kind::NoncanonicalSpecializedGenericTypeMetadataCache:
+    Printer << "cache variable for noncanonical specialized generic type metadata for ";
+    print(Node->getChild(0));
+    return nullptr;
   }
   printer_unreachable("bad node kind!");
 }

lib/Demangling/OldRemangler.cpp

@@ -2147,6 +2147,16 @@ void Remangler::mangleCanonicalSpecializedGenericTypeMetadataAccessFunction(
   Buffer << "Mb";
 }
 
+void Remangler::mangleNoncanonicalSpecializedGenericTypeMetadata(Node *node) {
+  mangleSingleChildNode(node);
+  Buffer << "MN";
+}
+
+void Remangler::mangleNoncanonicalSpecializedGenericTypeMetadataCache(Node *node) {
+  mangleSingleChildNode(node);
+  Buffer << "MJ";
+}
+
 /// The top-level interface to the remangler.
 std::string Demangle::mangleNodeOld(NodePointer node) {
   if (!node) return "";

lib/Demangling/Remangler.cpp

@@ -2552,6 +2552,16 @@ void Remangler::mangleMetadataInstantiationCache(Node *node) {
   Buffer << "MK";
 }
 
+void Remangler::mangleNoncanonicalSpecializedGenericTypeMetadata(Node *node) {
+  mangleSingleChildNode(node);
+  Buffer << "MN";
+}
+
+void Remangler::mangleNoncanonicalSpecializedGenericTypeMetadataCache(Node *node) {
+  mangleSingleChildNode(node);
+  Buffer << "MJ";
+}
+
 } // anonymous namespace
 
 /// The top-level interface to the remangler.

lib/IRGen/GenDecl.cpp

@@ -1426,7 +1426,22 @@ void IRGenerator::noteUseOfCanonicalSpecializedMetadataAccessor(
   }
 }
 
+static bool typeKindCanBePrespecialized(TypeKind theKind) {
+  switch (theKind) {
+  case TypeKind::Struct:
+  case TypeKind::BoundGenericStruct:
+  case TypeKind::Enum:
+  case TypeKind::BoundGenericEnum:
+  case TypeKind::Class:
+  case TypeKind::BoundGenericClass:
+    return true;
+  default:
+    return false;
+  }
+}
+
 void IRGenerator::noteUseOfSpecializedGenericTypeMetadata(CanType type) {
+  assert(typeKindCanBePrespecialized(type->getKind()));
   auto key = type->getAnyNominal();
   assert(key);
   assert(key->isGenericContext());
@@ -3736,6 +3751,22 @@ IRGenModule::getAddrOfTypeMetadataLazyCacheVariable(CanType type) {
   return variable;
 }
 
+llvm::Constant *
+IRGenModule::getAddrOfNoncanonicalSpecializedGenericTypeMetadataCacheVariable(CanType type) {
+  assert(!type->hasArchetype() && !type->hasTypeParameter());
+  LinkEntity entity = LinkEntity::forNoncanonicalSpecializedGenericTypeMetadataCacheVariable(type);
+  if (auto &entry = GlobalVars[entity]) {
+    return entry;
+  }
+  auto variable =
+    getAddrOfLLVMVariable(entity, ForDefinition, DebugTypeInfo());
+
+  cast<llvm::GlobalVariable>(variable)->setInitializer(
+    llvm::ConstantPointerNull::get(TypeMetadataPtrTy));
+
+  return variable;
+}
+
 /// Get or create a type metadata cache variable.  These are an
 /// implementation detail of type metadata access functions.
 llvm::Constant *
@@ -3817,6 +3848,9 @@ llvm::GlobalValue *IRGenModule::defineTypeMetadata(CanType concreteType,
                                                    llvm::StringRef section) {
   assert(init);
 
+  auto isPrespecialized = concreteType->getAnyGeneric() &&
+                          concreteType->getAnyGeneric()->isGenericContext();
+
   if (isPattern) {
     assert(isConstant && "Type metadata patterns must be constant");
     auto addr = getAddrOfTypeMetadataPattern(concreteType->getAnyNominal(),
@@ -3844,7 +3878,13 @@ llvm::GlobalValue *IRGenModule::defineTypeMetadata(CanType concreteType,
     adjustmentIndex = MetadataAdjustmentIndex::ValueType;
   }
 
-  auto entity = LinkEntity::forTypeMetadata(concreteType, addrKind);
+  auto entity =
+      (isPrespecialized &&
+       !irgen::isCanonicalInitializableTypeMetadataStaticallyAddressable(
+           *this, concreteType))
+          ? LinkEntity::forNoncanonicalSpecializedGenericTypeMetadata(
+                concreteType)
+          : LinkEntity::forTypeMetadata(concreteType, addrKind);
 
   auto DbgTy = DebugTypeInfo::getMetadata(MetatypeType::get(concreteType),
     entity.getDefaultDeclarationType(*this)->getPointerTo(),
@@ -3868,9 +3908,7 @@ llvm::GlobalValue *IRGenModule::defineTypeMetadata(CanType concreteType,
 
   // Don't define the alias for foreign type metadata or prespecialized generic
   // metadata, since neither is ABI.
-  if ((nominal && requiresForeignTypeMetadata(nominal)) ||
-      (concreteType->getAnyGeneric() &&
-       concreteType->getAnyGeneric()->isGenericContext()))
+  if ((nominal && requiresForeignTypeMetadata(nominal)) || isPrespecialized)
     return var;
 
   // For concrete metadata, declare the alias to its address point.
@@ -3892,13 +3930,18 @@ llvm::GlobalValue *IRGenModule::defineTypeMetadata(CanType concreteType,
 }
 
 /// Fetch the declaration of the (possibly uninitialized) metadata for a type.
-llvm::Constant *IRGenModule::getAddrOfTypeMetadata(CanType concreteType) {
-  return getAddrOfTypeMetadata(concreteType,
-                               SymbolReferenceKind::Absolute).getDirectValue();
+llvm::Constant *
+IRGenModule::getAddrOfTypeMetadata(CanType concreteType,
+                                   TypeMetadataCanonicality canonicality) {
+  return getAddrOfTypeMetadata(concreteType, SymbolReferenceKind::Absolute,
+                               canonicality)
+      .getDirectValue();
 }
 
-ConstantReference IRGenModule::getAddrOfTypeMetadata(CanType concreteType,
-                                               SymbolReferenceKind refKind) {
+ConstantReference
+IRGenModule::getAddrOfTypeMetadata(CanType concreteType,
+                                   SymbolReferenceKind refKind,
+                                   TypeMetadataCanonicality canonicality) {
   assert(!isa<UnboundGenericType>(concreteType));
 
   auto nominal = concreteType->getAnyNominal();
@@ -3952,12 +3995,20 @@ ConstantReference IRGenModule::getAddrOfTypeMetadata(CanType concreteType,
   Optional<LinkEntity> entity;
   DebugTypeInfo DbgTy;
 
-  if (fullMetadata) {
-    entity = LinkEntity::forTypeMetadata(concreteType,
-                                         TypeMetadataAddress::FullMetadata);
-  } else {
-    entity = LinkEntity::forTypeMetadata(concreteType,
-                                         TypeMetadataAddress::AddressPoint);
+  switch (canonicality) {
+  case TypeMetadataCanonicality::Canonical:
+    if (fullMetadata) {
+      entity = LinkEntity::forTypeMetadata(concreteType,
+                                           TypeMetadataAddress::FullMetadata);
+    } else {
+      entity = LinkEntity::forTypeMetadata(concreteType,
+                                           TypeMetadataAddress::AddressPoint);
+    }
+    break;
+  case TypeMetadataCanonicality::Noncanonical:
+    entity =
+        LinkEntity::forNoncanonicalSpecializedGenericTypeMetadata(concreteType);
+    break;
   }
   DbgTy = DebugTypeInfo::getMetadata(MetatypeType::get(concreteType),
                                      defaultVarTy->getPointerTo(), Size(0),

lib/IRGen/GenMeta.cpp

@@ -1977,8 +1977,9 @@ void irgen::emitLazySpecializedGenericTypeMetadata(IRGenModule &IGM,
                                         *type.getClassOrBoundGenericClass());
     break;
   default:
-    llvm_unreachable("Cannot statically specialize types of kind other than "
-                     "struct and enum.");
+    llvm_unreachable(
+        "Cannot statically specialize metadata for generic types of"
+        "kind other than struct, enum, and class.");
   }
 }
 
@@ -3476,7 +3477,9 @@ namespace {
       MetadataTrailingFlags flags = super::getTrailingFlags();
 
       flags.setIsStaticSpecialization(true);
-      flags.setIsCanonicalStaticSpecialization(true);
+      flags.setIsCanonicalStaticSpecialization(
+          irgen::isCanonicalInitializableTypeMetadataStaticallyAddressable(
+              IGM, type));
 
       return flags;
     }

lib/IRGen/IRGenMangler.h

@@ -118,6 +118,14 @@ class IRGenMangler : public Mangle::ASTMangler {
     return mangleTypeSymbol(type, "N");
   }
 
+  std::string mangleNoncanonicalTypeMetadata(Type type) {
+    return mangleTypeSymbol(type, "MN");
+  }
+
+  std::string mangleNoncanonicalSpecializedGenericTypeMetadataCache(Type type) {
+    return mangleTypeSymbol(type, "MJ");
+  }
+
   std::string mangleTypeMetadataPattern(const NominalTypeDecl *decl) {
     return mangleNominalTypeSymbol(decl, "MP");
   }