[feedback] Minor name and type changes

Minor refactors to improve readability and consistency between
FeedbackVectorSpec and FeedbackMetadata:

- Rename FeedbackVectorSpec::slots to slot_count.
- Rename FeedbackVectorSpec::closure_feedback_cells to
  create_closure_slot_count, likewise all related fields.
- Store FeedbackVectorSpec::slot_kinds_ as an array of
  FeedbackSlotKind.

Bug: v8:8888
Change-Id: I3a45177163d1484b1625de8dfba5c6c05cfc426d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2512908Reviewed-by: Mythri Alle <mythria@chromium.org>
Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Reviewed-by: Michael Stanton <mvstanton@chromium.org>
Commit-Queue: Michael Stanton <mvstanton@chromium.org>
Auto-Submit: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70943}

src/diagnostics/objects-debug.cc

@@ -583,7 +583,7 @@ void NativeContext::NativeContextVerify(Isolate* isolate) {
 }
 
 void FeedbackMetadata::FeedbackMetadataVerify(Isolate* isolate) {
-  if (slot_count() == 0 && closure_feedback_cell_count() == 0) {
+  if (slot_count() == 0 && create_closure_slot_count() == 0) {
     CHECK_EQ(ReadOnlyRoots(isolate).empty_feedback_metadata(), *this);
   } else {
     FeedbackMetadataIterator iter(*this);

src/diagnostics/objects-printer.cc

@@ -846,14 +846,13 @@ void FeedbackVectorSpec::Print() {
 }
 
 void FeedbackVectorSpec::FeedbackVectorSpecPrint(std::ostream& os) {  // NOLINT
-  int slot_count = slots();
-  os << " - slot_count: " << slot_count;
-  if (slot_count == 0) {
+  os << " - slot_count: " << slot_count();
+  if (slot_count() == 0) {
     os << " (empty)\n";
     return;
   }
 
-  for (int slot = 0; slot < slot_count;) {
+  for (int slot = 0; slot < slot_count();) {
     FeedbackSlotKind kind = GetKind(FeedbackSlot(slot));
     int entry_size = FeedbackMetadata::GetSlotSize(kind);
     DCHECK_LT(0, entry_size);
@@ -866,6 +865,7 @@ void FeedbackVectorSpec::FeedbackVectorSpecPrint(std::ostream& os) {  // NOLINT
 void FeedbackMetadata::FeedbackMetadataPrint(std::ostream& os) {
   PrintHeader(os, "FeedbackMetadata");
   os << "\n - slot_count: " << slot_count();
+  os << "\n - create_closure_slot_count: " << create_closure_slot_count();
 
   FeedbackMetadataIterator iter(*this);
   while (iter.HasNext()) {

src/heap/factory-base.cc

@@ -409,14 +409,14 @@ FactoryBase<Impl>::NewTemplateObjectDescription(
 
 template <typename Impl>
 Handle<FeedbackMetadata> FactoryBase<Impl>::NewFeedbackMetadata(
-    int slot_count, int feedback_cell_count, AllocationType allocation) {
+    int slot_count, int create_closure_slot_count, AllocationType allocation) {
   DCHECK_LE(0, slot_count);
   int size = FeedbackMetadata::SizeFor(slot_count);
   HeapObject result = AllocateRawWithImmortalMap(
       size, allocation, read_only_roots().feedback_metadata_map());
   Handle<FeedbackMetadata> data(FeedbackMetadata::cast(result), isolate());
   data->set_slot_count(slot_count);
-  data->set_closure_feedback_cell_count(feedback_cell_count);
+  data->set_create_closure_slot_count(create_closure_slot_count);
 
   // Initialize the data section to 0.
   int data_size = size - FeedbackMetadata::kHeaderSize;

src/heap/factory-base.h

@@ -137,7 +137,7 @@ class EXPORT_TEMPLATE_DECLARE(V8_EXPORT_PRIVATE) FactoryBase {
 
   // Allocates a FeedbackMedata object and zeroes the data section.
   Handle<FeedbackMetadata> NewFeedbackMetadata(
-      int slot_count, int feedback_cell_count,
+      int slot_count, int create_closure_slot_count,
       AllocationType allocation = AllocationType::kOld);
 
   Handle<CoverageInfo> NewCoverageInfo(const ZoneVector<SourceRange>& slots);

src/interpreter/bytecode-generator.cc

@@ -2531,7 +2531,7 @@ void BytecodeGenerator::BuildInstanceMemberInitialization(Register constructor,
 void BytecodeGenerator::VisitNativeFunctionLiteral(
     NativeFunctionLiteral* expr) {
   size_t entry = builder()->AllocateDeferredConstantPoolEntry();
-  int index = feedback_spec()->AddFeedbackCellForCreateClosure();
+  int index = feedback_spec()->AddCreateClosureSlot();
   uint8_t flags = CreateClosureFlags::Encode(false, false, false);
   builder()->CreateClosure(entry, index, flags);
   native_function_literals_.push_back(std::make_pair(expr, entry));
@@ -6658,7 +6658,7 @@ int BytecodeGenerator::GetCachedCreateClosureSlot(FunctionLiteral* literal) {
   if (index != -1) {
     return index;
   }
-  index = feedback_spec()->AddFeedbackCellForCreateClosure();
+  index = feedback_spec()->AddCreateClosureSlot();
   feedback_slot_cache()->Put(slot_kind, literal, index);
   return index;
 }

src/objects/feedback-vector-inl.h

@@ -35,8 +35,8 @@ CAST_ACCESSOR(ClosureFeedbackCellArray)
 
 INT32_ACCESSORS(FeedbackMetadata, slot_count, kSlotCountOffset)
 
-INT32_ACCESSORS(FeedbackMetadata, closure_feedback_cell_count,
-                kFeedbackCellCountOffset)
+INT32_ACCESSORS(FeedbackMetadata, create_closure_slot_count,
+                kCreateClosureSlotCountOffset)
 
 int32_t FeedbackMetadata::synchronized_slot_count() const {
   return base::Acquire_Load(

src/objects/feedback-vector.cc

@@ -20,7 +20,7 @@ namespace v8 {
 namespace internal {
 
 FeedbackSlot FeedbackVectorSpec::AddSlot(FeedbackSlotKind kind) {
-  int slot = slots();
+  int slot = slot_count();
   int entries_per_slot = FeedbackMetadata::GetSlotSize(kind);
   append(kind);
   for (int i = 1; i < entries_per_slot; i++) {
@@ -39,9 +39,7 @@ FeedbackSlot FeedbackVectorSpec::AddTypeProfileSlot() {
 bool FeedbackVectorSpec::HasTypeProfileSlot() const {
   FeedbackSlot slot =
       FeedbackVector::ToSlot(FeedbackVectorSpec::kTypeProfileSlotIndex);
-  if (slots() <= slot.ToInt()) {
-    return false;
-  }
+  if (slot_count() <= slot.ToInt()) return false;
   return GetKind(slot) == FeedbackSlotKind::kTypeProfile;
 }
 
@@ -82,10 +80,10 @@ Handle<FeedbackMetadata> FeedbackMetadata::New(LocalIsolate* isolate,
                                                const FeedbackVectorSpec* spec) {
   auto* factory = isolate->factory();
 
-  const int slot_count = spec == nullptr ? 0 : spec->slots();
-  const int closure_feedback_cell_count =
-      spec == nullptr ? 0 : spec->closure_feedback_cells();
-  if (slot_count == 0 && closure_feedback_cell_count == 0) {
+  const int slot_count = spec == nullptr ? 0 : spec->slot_count();
+  const int create_closure_slot_count =
+      spec == nullptr ? 0 : spec->create_closure_slot_count();
+  if (slot_count == 0 && create_closure_slot_count == 0) {
     return factory->empty_feedback_metadata();
   }
 #ifdef DEBUG
@@ -102,7 +100,7 @@ Handle<FeedbackMetadata> FeedbackMetadata::New(LocalIsolate* isolate,
 #endif
 
   Handle<FeedbackMetadata> metadata =
-      factory->NewFeedbackMetadata(slot_count, closure_feedback_cell_count);
+      factory->NewFeedbackMetadata(slot_count, create_closure_slot_count);
 
   // Initialize the slots. The raw data section has already been pre-zeroed in
   // NewFeedbackMetadata.
@@ -123,7 +121,7 @@ template Handle<FeedbackMetadata> FeedbackMetadata::New(
 
 bool FeedbackMetadata::SpecDiffersFrom(
     const FeedbackVectorSpec* other_spec) const {
-  if (other_spec->slots() != slot_count()) {
+  if (other_spec->slot_count() != slot_count()) {
     return true;
   }
 
@@ -221,7 +219,7 @@ Handle<ClosureFeedbackCellArray> ClosureFeedbackCellArray::New(
   Factory* factory = isolate->factory();
 
   int num_feedback_cells =
-      shared->feedback_metadata().closure_feedback_cell_count();
+      shared->feedback_metadata().create_closure_slot_count();
 
   Handle<ClosureFeedbackCellArray> feedback_cell_array =
       factory->NewClosureFeedbackCellArray(num_feedback_cells);

src/objects/feedback-vector.h

@@ -26,7 +26,7 @@ namespace internal {
 
 class IsCompiledScope;
 
-enum class FeedbackSlotKind {
+enum class FeedbackSlotKind : uint8_t {
   // This kind means that the slot points to the middle of other slot
   // which occupies more than one feedback vector element.
   // There must be no such slots in the system.
@@ -344,20 +344,17 @@ class FeedbackVector
 
 class V8_EXPORT_PRIVATE FeedbackVectorSpec {
  public:
-  explicit FeedbackVectorSpec(Zone* zone)
-      : slot_kinds_(zone), num_closure_feedback_cells_(0) {
+  explicit FeedbackVectorSpec(Zone* zone) : slot_kinds_(zone) {
     slot_kinds_.reserve(16);
   }
 
-  int slots() const { return static_cast<int>(slot_kinds_.size()); }
-  int closure_feedback_cells() const { return num_closure_feedback_cells_; }
+  int slot_count() const { return static_cast<int>(slot_kinds_.size()); }
+  int create_closure_slot_count() const { return create_closure_slot_count_; }
 
-  int AddFeedbackCellForCreateClosure() {
-    return num_closure_feedback_cells_++;
-  }
+  int AddCreateClosureSlot() { return create_closure_slot_count_++; }
 
   FeedbackSlotKind GetKind(FeedbackSlot slot) const {
-    return static_cast<FeedbackSlotKind>(slot_kinds_.at(slot.ToInt()));
+    return slot_kinds_.at(slot.ToInt());
   }
 
   bool HasTypeProfileSlot() const;
@@ -458,12 +455,11 @@ class V8_EXPORT_PRIVATE FeedbackVectorSpec {
  private:
   FeedbackSlot AddSlot(FeedbackSlotKind kind);
 
-  void append(FeedbackSlotKind kind) {
-    slot_kinds_.push_back(static_cast<unsigned char>(kind));
-  }
+  void append(FeedbackSlotKind kind) { slot_kinds_.push_back(kind); }
 
-  ZoneVector<unsigned char> slot_kinds_;
-  unsigned int num_closure_feedback_cells_;
+  STATIC_ASSERT(sizeof(FeedbackSlotKind) == sizeof(uint8_t));
+  ZoneVector<FeedbackSlotKind> slot_kinds_;
+  int create_closure_slot_count_ = 0;
 
   friend class SharedFeedbackSlot;
 };
@@ -502,7 +498,7 @@ class FeedbackMetadata : public HeapObject {
   // int32.
   // TODO(mythria): Consider using 16 bits for this and slot_count so that we
   // can save 4 bytes.
-  DECL_INT32_ACCESSORS(closure_feedback_cell_count)
+  DECL_INT32_ACCESSORS(create_closure_slot_count)
 
   // Get slot_count using an acquire load.
   inline int32_t synchronized_slot_count() const;
@@ -535,9 +531,13 @@ class FeedbackMetadata : public HeapObject {
     return OBJECT_POINTER_ALIGN(kHeaderSize + length(slot_count) * kInt32Size);
   }
 
-  static const int kSlotCountOffset = HeapObject::kHeaderSize;
-  static const int kFeedbackCellCountOffset = kSlotCountOffset + kInt32Size;
-  static const int kHeaderSize = kFeedbackCellCountOffset + kInt32Size;
+#define FIELDS(V)                              \
+  V(kSlotCountOffset, kInt32Size)              \
+  V(kCreateClosureSlotCountOffset, kInt32Size) \
+  V(kHeaderSize, 0)
+
+  DEFINE_FIELD_OFFSET_CONSTANTS(HeapObject::kHeaderSize, FIELDS)
+#undef FIELDS
 
   class BodyDescriptor;
 

test/cctest/test-feedback-vector.cc

@@ -89,7 +89,7 @@ TEST(VectorStructure) {
   {
     FeedbackVectorSpec spec(&zone);
     spec.AddForInSlot();
-    spec.AddFeedbackCellForCreateClosure();
+    spec.AddCreateClosureSlot();
     spec.AddForInSlot();
     vector = NewFeedbackVector(isolate, &spec);
     FeedbackVectorHelper helper(vector);