Reland "[serializer] share class positions tuple across contexts"

This reverts commit b1eb340d.

Bug: v8:8761
Change-Id: Icd952e16e85a7beb07874cb8979eec4cf1991a14
Reviewed-on: https://chromium-review.googlesource.com/c/1454922Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Commit-Queue: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59391}

src/compiler/types.cc

@@ -342,6 +342,7 @@ Type::bitset BitsetType::Lub(const MapRefLike& map) {
     case ALIASED_ARGUMENTS_ENTRY_TYPE:
     case PROMISE_CAPABILITY_TYPE:
     case PROMISE_REACTION_TYPE:
+    case CLASS_POSITIONS_TYPE:
     case DEBUG_INFO_TYPE:
     case STACK_FRAME_INFO_TYPE:
     case SMALL_ORDERED_HASH_MAP_TYPE:

src/heap/factory.cc

@@ -3785,6 +3785,14 @@ Handle<String> Factory::NumberToString(Smi number, bool check_cache) {
                                 check_cache);
 }
 
+Handle<ClassPositions> Factory::NewClassPositions(int start, int end) {
+  Handle<ClassPositions> class_positions =
+      Handle<ClassPositions>::cast(NewStruct(CLASS_POSITIONS_TYPE, TENURED));
+  class_positions->set_start(start);
+  class_positions->set_end(end);
+  return class_positions;
+}
+
 Handle<DebugInfo> Factory::NewDebugInfo(Handle<SharedFunctionInfo> shared) {
   DCHECK(!shared->HasDebugInfo());
   Heap* heap = isolate()->heap();

src/heap/factory.h

@@ -889,6 +889,7 @@ class V8_EXPORT_PRIVATE Factory {
       MessageTemplate message, Handle<Object> argument, int start_position,
       int end_position, Handle<Script> script, Handle<Object> stack_frames);
 
+  Handle<ClassPositions> NewClassPositions(int start, int end);
   Handle<DebugInfo> NewDebugInfo(Handle<SharedFunctionInfo> shared);
 
   Handle<CoverageInfo> NewCoverageInfo(const ZoneVector<SourceRange>& slots);

src/objects-debug.cc

@@ -1814,6 +1814,12 @@ void Tuple3::Tuple3Verify(Isolate* isolate) {
   VerifyObjectField(isolate, kValue3Offset);
 }
 
+void ClassPositions::ClassPositionsVerify(Isolate* isolate) {
+  CHECK(IsClassPositions());
+  VerifySmiField(kStartOffset);
+  VerifySmiField(kEndOffset);
+}
+
 void ObjectBoilerplateDescription::ObjectBoilerplateDescriptionVerify(
     Isolate* isolate) {
   CHECK(IsObjectBoilerplateDescription());

src/objects-definitions.h

@@ -98,6 +98,7 @@ namespace internal {
   V(ALLOCATION_MEMENTO_TYPE)                                       \
   V(ASM_WASM_DATA_TYPE)                                            \
   V(ASYNC_GENERATOR_REQUEST_TYPE)                                  \
+  V(CLASS_POSITIONS_TYPE)                                          \
   V(DEBUG_INFO_TYPE)                                               \
   V(FUNCTION_TEMPLATE_INFO_TYPE)                                   \
   V(FUNCTION_TEMPLATE_RARE_DATA_TYPE)                              \
@@ -321,6 +322,7 @@ namespace internal {
   V(_, ASM_WASM_DATA_TYPE, AsmWasmData, asm_wasm_data)                        \
   V(_, ASYNC_GENERATOR_REQUEST_TYPE, AsyncGeneratorRequest,                   \
     async_generator_request)                                                  \
+  V(_, CLASS_POSITIONS_TYPE, ClassPositions, class_positions)                 \
   V(_, DEBUG_INFO_TYPE, DebugInfo, debug_info)                                \
   V(_, FUNCTION_TEMPLATE_INFO_TYPE, FunctionTemplateInfo,                     \
     function_template_info)                                                   \

src/objects-printer.cc

@@ -1744,6 +1744,13 @@ void Tuple3::Tuple3Print(std::ostream& os) {  // NOLINT
   os << "\n";
 }
 
+void ClassPositions::ClassPositionsPrint(std::ostream& os) {  // NOLINT
+  PrintHeader(os, "ClassPositions");
+  os << "\n - start position: " << start();
+  os << "\n - end position: " << end();
+  os << "\n";
+}
+
 void ArrayBoilerplateDescription::ArrayBoilerplateDescriptionPrint(
     std::ostream& os) {  // NOLINT
   PrintHeader(os, "ArrayBoilerplateDescription");

src/objects.cc

@@ -2143,6 +2143,10 @@ void Tuple3::BriefPrintDetails(std::ostream& os) {
      << Brief(value3());
 }
 
+void ClassPositions::BriefPrintDetails(std::ostream& os) {
+  os << " " << start() << ", " << end();
+}
+
 void ArrayBoilerplateDescription::BriefPrintDetails(std::ostream& os) {
   os << " " << elements_kind() << ", " << Brief(constant_elements());
 }

src/objects/instance-type.h

@@ -171,6 +171,7 @@ enum InstanceType : uint16_t {
   ALLOCATION_MEMENTO_TYPE,
   ASM_WASM_DATA_TYPE,
   ASYNC_GENERATOR_REQUEST_TYPE,
+  CLASS_POSITIONS_TYPE,
   DEBUG_INFO_TYPE,
   FUNCTION_TEMPLATE_INFO_TYPE,
   FUNCTION_TEMPLATE_RARE_DATA_TYPE,

src/objects/js-objects.cc

@@ -5384,10 +5384,11 @@ Handle<String> JSFunction::ToString(Handle<JSFunction> function) {
   // Check if we should print {function} as a class.
   Handle<Object> maybe_class_positions = JSReceiver::GetDataProperty(
       function, isolate->factory()->class_positions_symbol());
-  if (maybe_class_positions->IsTuple2()) {
-    Tuple2 class_positions = Tuple2::cast(*maybe_class_positions);
-    int start_position = Smi::ToInt(class_positions->value1());
-    int end_position = Smi::ToInt(class_positions->value2());
+  if (maybe_class_positions->IsClassPositions()) {
+    ClassPositions class_positions =
+        ClassPositions::cast(*maybe_class_positions);
+    int start_position = class_positions->start();
+    int end_position = class_positions->end();
     Handle<String> script_source(
         String::cast(Script::cast(shared_info->script())->source()), isolate);
     return isolate->factory()->NewSubString(script_source, start_position,

src/objects/literal-objects.cc

@@ -493,10 +493,8 @@ Handle<ClassBoilerplate> ClassBoilerplate::BuildClassBoilerplate(
                             attribs);
   }
   {
-    Handle<Smi> start_position(Smi::FromInt(expr->start_position()), isolate);
-    Handle<Smi> end_position(Smi::FromInt(expr->end_position()), isolate);
-    Handle<Tuple2> class_positions =
-        factory->NewTuple2(start_position, end_position, NOT_TENURED);
+    Handle<ClassPositions> class_positions = factory->NewClassPositions(
+        expr->start_position(), expr->end_position());
     static_desc.AddConstant(isolate, factory->class_positions_symbol(),
                             class_positions, DONT_ENUM);
   }

src/objects/struct-inl.h

@@ -24,11 +24,15 @@ Tuple2::Tuple2(Address ptr) : Struct(ptr) {}
 Tuple3::Tuple3(Address ptr) : Tuple2(ptr) {}
 OBJECT_CONSTRUCTORS_IMPL(AccessorPair, Struct)
 
+OBJECT_CONSTRUCTORS_IMPL(ClassPositions, Struct)
+
 CAST_ACCESSOR(AccessorPair)
 CAST_ACCESSOR(Struct)
 CAST_ACCESSOR(Tuple2)
 CAST_ACCESSOR(Tuple3)
 
+CAST_ACCESSOR(ClassPositions)
+
 void Struct::InitializeBody(int object_size) {
   Object value = GetReadOnlyRoots().undefined_value();
   for (int offset = kHeaderSize; offset < object_size; offset += kPointerSize) {
@@ -43,6 +47,9 @@ ACCESSORS(Tuple3, value3, Object, kValue3Offset)
 ACCESSORS(AccessorPair, getter, Object, kGetterOffset)
 ACCESSORS(AccessorPair, setter, Object, kSetterOffset)
 
+SMI_ACCESSORS(ClassPositions, start, kStartOffset)
+SMI_ACCESSORS(ClassPositions, end, kEndOffset)
+
 Object AccessorPair::get(AccessorComponent component) {
   return component == ACCESSOR_GETTER ? getter() : setter();
 }

src/objects/struct.h

@@ -119,6 +119,31 @@ class AccessorPair : public Struct {
   OBJECT_CONSTRUCTORS(AccessorPair, Struct);
 };
 
+class ClassPositions : public Struct {
+ public:
+  DECL_INT_ACCESSORS(start)
+  DECL_INT_ACCESSORS(end)
+
+  DECL_CAST(ClassPositions)
+
+  // Dispatched behavior.
+  DECL_PRINTER(ClassPositions)
+  DECL_VERIFIER(ClassPositions)
+  void BriefPrintDetails(std::ostream& os);
+
+// Layout description.
+#define CLASS_POSITIONS_FIELDS(V) \
+  V(kStartOffset, kTaggedSize)    \
+  V(kEndOffset, kTaggedSize)      \
+  /* Total size. */               \
+  V(kSize, 0)
+
+  DEFINE_FIELD_OFFSET_CONSTANTS(HeapObject::kHeaderSize, CLASS_POSITIONS_FIELDS)
+#undef CLASS_POSITIONS_FIELDS
+
+  OBJECT_CONSTRUCTORS(ClassPositions, Struct);
+};
+
 }  // namespace internal
 }  // namespace v8
 

src/snapshot/partial-serializer.cc

@@ -133,7 +133,7 @@ bool PartialSerializer::ShouldBeInThePartialSnapshotCache(HeapObject o) {
   DCHECK(!o->IsScript());
   return o->IsName() || o->IsSharedFunctionInfo() || o->IsHeapNumber() ||
          o->IsCode() || o->IsScopeInfo() || o->IsAccessorInfo() ||
-         o->IsTemplateInfo() ||
+         o->IsTemplateInfo() || o->IsClassPositions() ||
          o->map() == ReadOnlyRoots(startup_serializer_->isolate())
                          .fixed_cow_array_map();
 }

test/cctest/test-serialize.cc

@@ -3923,5 +3923,27 @@ TEST(CachedCompileFunctionInContext) {
   }
 }
 
+UNINITIALIZED_TEST(SnapshotCreatorAnonClassWithKeep) {
+  DisableAlwaysOpt();
+  v8::SnapshotCreator creator;
+  v8::Isolate* isolate = creator.GetIsolate();
+  {
+    v8::HandleScope handle_scope(isolate);
+    {
+      v8::Local<v8::Context> context = v8::Context::New(isolate);
+      v8::Context::Scope context_scope(context);
+      CompileRun(
+          "function Foo() { return class {}; } \n"
+          "class Bar extends Foo() {}\n"
+          "Foo()\n");
+      creator.SetDefaultContext(context);
+    }
+  }
+  v8::StartupData blob =
+      creator.CreateBlob(v8::SnapshotCreator::FunctionCodeHandling::kKeep);
+
+  delete[] blob.data;
+}
+
 }  // namespace internal
 }  // namespace v8