Reland "[torque] allow exported classes with custom C++ class"

This is a reland of 26f10ecd

Change compared to original CL:
The deserializer changes StrongDescriptorArray to DescriptorArray.
Since this CL uses separate BodyDescriptors for the two kinds of
descriptor arrays, this caused a DCHECK failure when the deserializer
changes the map while the object is visited from the concurrent marking
thread. Fix this by disabling the corresponding checks.


Original change's description:
> [torque] allow exported classes with custom C++ class
>
> Introduce a new annotation @customCppClass that can be used for
> non-extern @export classes, that is, generate everything, remove
> boilerplate from all the internal lists and switches, but allow
> a custom C++ class, which in turn also allows overwriting the generated
> print and verify functions.
>
> Port DescriptorArray and StrongDescriptorArray as an example.
>
> Bug: v8:7793
> Change-Id: I744e52fb4102ac49c0097f1c95bb17d301975bf0
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2489687
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
> Reviewed-by: Seth Brenith <seth.brenith@microsoft.com>
> Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#70989}

Bug: v8:7793
Change-Id: I7505fb111896991d16d7d113704c8c3676669f34
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2526383Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#71048}

src/compiler/types.cc

@@ -294,8 +294,6 @@ Type::bitset BitsetType::Lub(const MapRefLike& map) {
     case BYTECODE_ARRAY_TYPE:
     case OBJECT_BOILERPLATE_DESCRIPTION_TYPE:
     case ARRAY_BOILERPLATE_DESCRIPTION_TYPE:
-    case DESCRIPTOR_ARRAY_TYPE:
-    case STRONG_DESCRIPTOR_ARRAY_TYPE:
     case TRANSITION_ARRAY_TYPE:
     case FEEDBACK_CELL_TYPE:
     case CLOSURE_FEEDBACK_CELL_ARRAY_TYPE:

src/diagnostics/objects-debug.cc

@@ -252,11 +252,6 @@ void HeapObject::HeapObjectVerify(Isolate* isolate) {
       TORQUE_INSTANCE_CHECKERS_MULTIPLE_FULLY_DEFINED(MAKE_TORQUE_CASE)
 #undef MAKE_TORQUE_CASE
 
-    case DESCRIPTOR_ARRAY_TYPE:
-    case STRONG_DESCRIPTOR_ARRAY_TYPE:
-      DescriptorArray::cast(*this).DescriptorArrayVerify(isolate);
-      break;
-
     case FOREIGN_TYPE:
       break;  // No interesting fields.
 

src/diagnostics/objects-printer.cc

@@ -169,10 +169,6 @@ void HeapObject::HeapObjectPrint(std::ostream& os) {  // NOLINT
       TORQUE_INSTANCE_CHECKERS_MULTIPLE_FULLY_DEFINED(MAKE_TORQUE_CASE)
 #undef MAKE_TORQUE_CASE
 
-    case DESCRIPTOR_ARRAY_TYPE:
-    case STRONG_DESCRIPTOR_ARRAY_TYPE:
-      DescriptorArray::cast(*this).DescriptorArrayPrint(os);
-      break;
     case FOREIGN_TYPE:
       Foreign::cast(*this).ForeignPrint(os);
       break;

src/heap/concurrent-marking.cc

@@ -347,6 +347,13 @@ FixedArray ConcurrentMarkingVisitor::Cast(HeapObject object) {
   return FixedArray::unchecked_cast(object);
 }
 
+// The Deserializer changes the map from StrongDescriptorArray to
+// DescriptorArray
+template <>
+StrongDescriptorArray ConcurrentMarkingVisitor::Cast(HeapObject object) {
+  return StrongDescriptorArray::unchecked_cast(DescriptorArray::cast(object));
+}
+
 class ConcurrentMarking::JobTask : public v8::JobTask {
  public:
   JobTask(ConcurrentMarking* concurrent_marking, unsigned mark_compact_epoch,

src/heap/factory.h

@@ -121,6 +121,10 @@ class V8_EXPORT_PRIVATE Factory : public FactoryBase<Factory> {
 
 #include "torque-generated/factory.inc"
 
+  // Avoid the Torque-generated factory function to shadow the one from
+  // FactoryBase.
+  using FactoryBase::NewDescriptorArray;
+
   Handle<Oddball> NewOddball(Handle<Map> map, const char* to_string,
                              Handle<Object> to_number, const char* type_of,
                              byte kind);

src/heap/objects-visiting.h

@@ -25,7 +25,6 @@ namespace internal {
   V(Context)                           \
   V(CoverageInfo)                      \
   V(DataHandler)                       \
-  V(DescriptorArray)                   \
   V(EmbedderDataArray)                 \
   V(EphemeronHashTable)                \
   V(FeedbackCell)                      \

src/heap/setup-heap-internal.cc

@@ -386,7 +386,6 @@ bool Heap::CreateInitialMaps() {
     ALLOCATE_PRIMITIVE_MAP(SYMBOL_TYPE, Symbol::kSize, symbol,
                            Context::SYMBOL_FUNCTION_INDEX)
     ALLOCATE_MAP(FOREIGN_TYPE, Foreign::kSize, foreign)
-    ALLOCATE_VARSIZE_MAP(STRONG_DESCRIPTOR_ARRAY_TYPE, strong_descriptor_array)
 
     ALLOCATE_PRIMITIVE_MAP(ODDBALL_TYPE, Oddball::kSize, boolean,
                            Context::BOOLEAN_FUNCTION_INDEX);
@@ -428,8 +427,11 @@ bool Heap::CreateInitialMaps() {
     TORQUE_DEFINED_FIXED_INSTANCE_TYPE_LIST(TORQUE_ALLOCATE_MAP);
 #undef TORQUE_ALLOCATE_MAP
 
-#define TORQUE_ALLOCATE_VARSIZE_MAP(NAME, Name, name) \
-  ALLOCATE_VARSIZE_MAP(NAME, name)
+#define TORQUE_ALLOCATE_VARSIZE_MAP(NAME, Name, name)                   \
+  /* The DescriptorArray map is pre-allocated and initialized above. */ \
+  if (NAME != DESCRIPTOR_ARRAY_TYPE) {                                  \
+    ALLOCATE_VARSIZE_MAP(NAME, name)                                    \
+  }
     TORQUE_DEFINED_VARSIZE_INSTANCE_TYPE_LIST(TORQUE_ALLOCATE_VARSIZE_MAP);
 #undef TORQUE_ALLOCATE_VARSIZE_MAP
 

src/objects/descriptor-array.h

@@ -170,9 +170,7 @@ class DescriptorArray
                 "Weak fields extend up to the end of the header.");
   static_assert(kDescriptorsOffset == kHeaderSize,
                 "Variable-size array follows header.");
-  // We use this visitor to also visitor to also visit the enum_cache, which is
-  // the only tagged field in the header, and placed at the end of the header.
-  using BodyDescriptor = FlexibleWeakBodyDescriptor<kStartOfStrongFieldsOffset>;
+  class BodyDescriptor;
 
   // Layout of descriptor.
   // Naming is consistent with Dictionary classes for easy templating.

src/objects/descriptor-array.tq

@@ -16,8 +16,9 @@ struct DescriptorEntry {
   value: JSAny|Weak<Map>|AccessorInfo|AccessorPair|ClassPositions;
 }
 
-@generateCppClass
-extern class DescriptorArray extends HeapObject {
+@export
+@customCppClass
+class DescriptorArray extends HeapObject {
   const number_of_all_descriptors: uint16;
   number_of_descriptors: uint16;
   raw_number_of_marked_descriptors: uint16;
@@ -27,5 +28,4 @@ extern class DescriptorArray extends HeapObject {
 }
 
 // A descriptor array where all values are held strongly.
-extern class StrongDescriptorArray extends DescriptorArray
-    generates 'TNode<DescriptorArray>';
+class StrongDescriptorArray extends DescriptorArray {}

src/objects/map.cc

@@ -202,10 +202,6 @@ VisitorId Map::GetVisitorId(Map map) {
     case PROPERTY_CELL_TYPE:
       return kVisitPropertyCell;
 
-    case DESCRIPTOR_ARRAY_TYPE:
-    case STRONG_DESCRIPTOR_ARRAY_TYPE:
-      return kVisitDescriptorArray;
-
     case TRANSITION_ARRAY_TYPE:
       return kVisitTransitionArray;
 

src/objects/map.h

@@ -40,7 +40,6 @@ enum InstanceType : uint16_t;
   V(CodeDataContainer)                 \
   V(Context)                           \
   V(DataHandler)                       \
-  V(DescriptorArray)                   \
   V(EmbedderDataArray)                 \
   V(EphemeronHashTable)                \
   V(FeedbackCell)                      \

src/objects/object-list-macros.h

@@ -104,7 +104,6 @@ class ZoneForwardList;
   V(DataHandler)                               \
   V(DeoptimizationData)                        \
   V(DependentCode)                             \
-  V(DescriptorArray)                           \
   V(EmbedderDataArray)                         \
   V(EphemeronHashTable)                        \
   V(ExternalOneByteString)                     \
@@ -281,7 +280,6 @@ class ZoneForwardList;
   V(ModuleContext)                           \
   V(NonNullForeign)                          \
   V(ScriptContext)                           \
-  V(StrongDescriptorArray)                   \
   V(WithContext)
 
 #define HEAP_OBJECT_TYPE_LIST(V)    \

src/objects/objects-body-descriptors-inl.h

@@ -945,10 +945,6 @@ ReturnType BodyDescriptorApply(InstanceType type, T1 p1, T2 p2, T3 p3, T4 p4) {
                                                                   p4);
     case PROPERTY_ARRAY_TYPE:
       return Op::template apply<PropertyArray::BodyDescriptor>(p1, p2, p3, p4);
-    case DESCRIPTOR_ARRAY_TYPE:
-    case STRONG_DESCRIPTOR_ARRAY_TYPE:
-      return Op::template apply<DescriptorArray::BodyDescriptor>(p1, p2, p3,
-                                                                 p4);
     case TRANSITION_ARRAY_TYPE:
       return Op::template apply<TransitionArray::BodyDescriptor>(p1, p2, p3,
                                                                  p4);

src/objects/torque-defined-classes.h

@@ -4,6 +4,7 @@
 #ifndef V8_OBJECTS_TORQUE_DEFINED_CLASSES_H_
 #define V8_OBJECTS_TORQUE_DEFINED_CLASSES_H_
 
+#include "src/objects/descriptor-array.h"
 #include "src/objects/fixed-array.h"
 #include "src/objects/heap-object.h"
 #include "src/objects/objects.h"

src/roots/roots.h

@@ -85,8 +85,6 @@ class Symbol;
   V(Map, bytecode_array_map, BytecodeArrayMap)                                 \
   V(Map, code_data_container_map, CodeDataContainerMap)                        \
   V(Map, coverage_info_map, CoverageInfoMap)                                   \
-  V(Map, descriptor_array_map, DescriptorArrayMap)                             \
-  V(Map, strong_descriptor_array_map, StrongDescriptorArrayMap)                \
   V(Map, fixed_double_array_map, FixedDoubleArrayMap)                          \
   V(Map, global_dictionary_map, GlobalDictionaryMap)                           \
   V(Map, many_closures_cell_map, ManyClosuresCellMap)                          \

src/torque/constants.h

@@ -85,6 +85,7 @@ static const char* const ANNOTATION_ABSTRACT = "@abstract";
 static const char* const ANNOTATION_HAS_SAME_INSTANCE_TYPE_AS_PARENT =
     "@hasSameInstanceTypeAsParent";
 static const char* const ANNOTATION_GENERATE_CPP_CLASS = "@generateCppClass";
+static const char* const ANNOTATION_CUSTOM_CPP_CLASS = "@customCppClass";
 static const char* const ANNOTATION_HIGHEST_INSTANCE_TYPE_WITHIN_PARENT =
     "@highestInstanceTypeWithinParentClassRange";
 static const char* const ANNOTATION_LOWEST_INSTANCE_TYPE_WITHIN_PARENT =
@@ -135,6 +136,7 @@ enum class ClassFlag {
   kIsShape = 1 << 5,
   kHasSameInstanceTypeAsParent = 1 << 6,
   kGenerateCppClassDefinitions = 1 << 7,
+  kCustomCppClass = 1 << 8,
   kHighestInstanceTypeWithinParent = 1 << 9,
   kLowestInstanceTypeWithinParent = 1 << 10,
   kUndefinedLayout = 1 << 11,

src/torque/implementation-visitor.cc

@@ -3829,7 +3829,7 @@ void CppClassGenerator::GenerateClass() {
 
   hdr_ << "};\n\n";
 
-  if (!type_->IsExtern()) {
+  if (type_->ShouldGenerateFullClassDefinition()) {
     GenerateClassExport(type_, hdr_, inl_);
   }
 }
@@ -4542,8 +4542,10 @@ void ImplementationVisitor::GenerateBodyDescriptors(
       if (type->size().SingleValue()) {
         h_contents << "    return " << *type->size().SingleValue() << ";\n";
       } else {
+        // We use an unchecked_cast here because this is used for concurrent
+        // marking, where we shouldn't re-read the map.
         h_contents << "    return " << name
-                   << "::cast(raw_object).AllocatedSize();\n";
+                   << "::unchecked_cast(raw_object).AllocatedSize();\n";
       }
       h_contents << "  }\n\n";
 

src/torque/torque-parser.cc

@@ -889,8 +889,9 @@ base::Optional<ParseResult> MakeClassDeclaration(
       child_results,
       {ANNOTATION_GENERATE_PRINT, ANNOTATION_NO_VERIFIER, ANNOTATION_ABSTRACT,
        ANNOTATION_HAS_SAME_INSTANCE_TYPE_AS_PARENT,
-       ANNOTATION_GENERATE_CPP_CLASS, ANNOTATION_GENERATE_BODY_DESCRIPTOR,
-       ANNOTATION_EXPORT, ANNOTATION_DO_NOT_GENERATE_CAST,
+       ANNOTATION_GENERATE_CPP_CLASS, ANNOTATION_CUSTOM_CPP_CLASS,
+       ANNOTATION_GENERATE_BODY_DESCRIPTOR, ANNOTATION_EXPORT,
+       ANNOTATION_DO_NOT_GENERATE_CAST,
        ANNOTATION_HIGHEST_INSTANCE_TYPE_WITHIN_PARENT,
        ANNOTATION_LOWEST_INSTANCE_TYPE_WITHIN_PARENT},
       {ANNOTATION_RESERVE_BITS_IN_INSTANCE_TYPE,
@@ -909,6 +910,9 @@ base::Optional<ParseResult> MakeClassDeclaration(
   if (annotations.Contains(ANNOTATION_GENERATE_CPP_CLASS)) {
     flags |= ClassFlag::kGenerateCppClassDefinitions;
   }
+  if (annotations.Contains(ANNOTATION_CUSTOM_CPP_CLASS)) {
+    flags |= ClassFlag::kCustomCppClass;
+  }
   if (annotations.Contains(ANNOTATION_DO_NOT_GENERATE_CAST)) {
     flags |= ClassFlag::kDoNotGenerateCast;
   }

src/torque/type-visitor.cc

@@ -287,6 +287,15 @@ const ClassType* TypeVisitor::ComputeType(
     Error("Class \"", decl->name->value,
           "\" requires a layout but doesn't have one");
   }
+  if (flags & ClassFlag::kCustomCppClass) {
+    if (!(flags & ClassFlag::kExport)) {
+      Error("Only exported classes can have a custom C++ class.");
+    }
+    if (flags & ClassFlag::kExtern) {
+      Error("No need to specify ", ANNOTATION_CUSTOM_CPP_CLASS,
+            ", extern classes always have a custom C++ class.");
+    }
+  }
   if (flags & ClassFlag::kExtern) {
     if (decl->generates) {
       bool enforce_tnode_type = true;

src/torque/types.h

@@ -683,6 +683,9 @@ class ClassType final : public AggregateType {
     return flags_ & ClassFlag::kGenerateCppClassDefinitions || !IsExtern() ||
            ShouldGenerateBodyDescriptor();
   }
+  bool ShouldGenerateFullClassDefinition() const {
+    return !IsExtern() && !(flags_ & ClassFlag::kCustomCppClass);
+  }
   bool ShouldExport() const { return flags_ & ClassFlag::kExport; }
   bool IsShape() const { return flags_ & ClassFlag::kIsShape; }
   bool HasStaticSize() const;