[heap] Add trivial BodyDescriptorWeak for objects without weak fields.

This patch also changes the visitor of BytecodeArray to use
BytecodeArray::BodyDescriptor.

BUG=chromium:733159

Change-Id: I2ac72c97ec51996b5b100c447b543895180f4f78
Reviewed-on: https://chromium-review.googlesource.com/535674Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#45955}

src/heap/objects-visiting-inl.h

@@ -158,7 +158,7 @@ void StaticMarkingVisitor<StaticVisitor>::Initialize() {
 
   table_.Register(
       kVisitAllocationSite,
-      &FixedBodyVisitor<StaticVisitor, AllocationSite::MarkingBodyDescriptor,
+      &FixedBodyVisitor<StaticVisitor, AllocationSite::BodyDescriptorWeak,
                         void>::Visit);
 
   table_.Register(kVisitByteArray, &DataObjectVisitor::Visit);
@@ -295,7 +295,7 @@ void StaticMarkingVisitor<StaticVisitor>::VisitCodeAgeSequence(
 template <typename StaticVisitor>
 void StaticMarkingVisitor<StaticVisitor>::VisitBytecodeArray(
     Map* map, HeapObject* object) {
-  FixedBodyVisitor<StaticVisitor, BytecodeArray::MarkingBodyDescriptor,
+  FlexibleBodyVisitor<StaticVisitor, BytecodeArray::BodyDescriptor,
                       void>::Visit(map, object);
   BytecodeArray::cast(object)->MakeOlder();
 }

src/objects-body-descriptors-inl.h

@@ -370,7 +370,7 @@ class JSWeakCollection::BodyDescriptorImpl final : public BodyDescriptorBase {
   template <typename ObjectVisitor>
   static inline void IterateBody(HeapObject* obj, int object_size,
                                  ObjectVisitor* v) {
-    if (body_visiting_policy == kVisitStrong) {
+    if (body_visiting_policy == kIgnoreWeakness) {
       IterateBodyImpl(obj, kPropertiesOffset, object_size, v);
     } else {
       IteratePointers(obj, kPropertiesOffset, kTableOffset, v);
@@ -381,7 +381,7 @@ class JSWeakCollection::BodyDescriptorImpl final : public BodyDescriptorBase {
   template <typename StaticVisitor>
   static inline void IterateBody(HeapObject* obj, int object_size) {
     Heap* heap = obj->GetHeap();
-    if (body_visiting_policy == kVisitStrong) {
+    if (body_visiting_policy == kIgnoreWeakness) {
       IterateBodyImpl<StaticVisitor>(heap, obj, kPropertiesOffset, object_size);
     } else {
       IteratePointers<StaticVisitor>(heap, obj, kPropertiesOffset,

src/objects.h

@@ -2587,7 +2587,12 @@ class JSObject: public JSReceiver {
       (kMaxInstanceSize - kHeaderSize) >> kPointerSizeLog2;
 
   class BodyDescriptor;
+  // No weak fields.
+  typedef BodyDescriptor BodyDescriptorWeak;
+
   class FastBodyDescriptor;
+  // No weak fields.
+  typedef FastBodyDescriptor FastBodyDescriptorWeak;
 
   // Gets the number of currently used elements.
   int GetFastElementsUsage();
@@ -2804,6 +2809,8 @@ class FixedArray: public FixedArrayBase {
 #endif
 
   typedef FlexibleBodyDescriptor<kHeaderSize> BodyDescriptor;
+  // No weak fields.
+  typedef BodyDescriptor BodyDescriptorWeak;
 
  protected:
   // Set operation on FixedArray without using write barriers. Can
@@ -2861,6 +2868,8 @@ class FixedDoubleArray: public FixedArrayBase {
   DECLARE_VERIFIER(FixedDoubleArray)
 
   class BodyDescriptor;
+  // No weak fields.
+  typedef BodyDescriptor BodyDescriptorWeak;
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(FixedDoubleArray);
@@ -3132,6 +3141,8 @@ class ByteArray: public FixedArrayBase {
   static const int kMaxLength = kMaxSize - kHeaderSize;
 
   class BodyDescriptor;
+  // No weak fields.
+  typedef BodyDescriptor BodyDescriptorWeak;
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(ByteArray);
@@ -3269,11 +3280,9 @@ class BytecodeArray : public FixedArrayBase {
   static const int kPointerFieldsBeginOffset = kConstantPoolOffset;
   static const int kPointerFieldsEndOffset = kFrameSizeOffset;
 
-  typedef FixedBodyDescriptor<kPointerFieldsBeginOffset,
-                              kPointerFieldsEndOffset, kHeaderSize>
-      MarkingBodyDescriptor;
-
   class BodyDescriptor;
+  // No weak fields.
+  typedef BodyDescriptor BodyDescriptorWeak;
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(BytecodeArray);
@@ -3362,6 +3371,8 @@ class FixedTypedArrayBase: public FixedArrayBase {
   static const size_t kMaxLength = Smi::kMaxValue;
 
   class BodyDescriptor;
+  // No weak fields.
+  typedef BodyDescriptor BodyDescriptorWeak;
 
   inline int size();
 
@@ -5414,6 +5425,8 @@ class JSMessageObject: public JSObject {
   typedef FixedBodyDescriptor<HeapObject::kMapOffset,
                               kStackFramesOffset + kPointerSize,
                               kSize> BodyDescriptor;
+  // No weak fields.
+  typedef BodyDescriptor BodyDescriptorWeak;
 };
 
 class JSPromise;
@@ -5819,14 +5832,15 @@ class AllocationSite: public Struct {
   static const int kPointerFieldsBeginOffset = kTransitionInfoOffset;
   static const int kPointerFieldsEndOffset = kWeakNextOffset;
 
-  typedef FixedBodyDescriptor<kPointerFieldsBeginOffset,
-                              kPointerFieldsEndOffset, kSize>
-      MarkingBodyDescriptor;
-
-  // For other visitors, use the fixed body descriptor below.
+  // Ignores weakness.
   typedef FixedBodyDescriptor<HeapObject::kHeaderSize, kSize, kSize>
       BodyDescriptor;
 
+  // Respects weakness.
+  typedef FixedBodyDescriptor<kPointerFieldsBeginOffset,
+                              kPointerFieldsEndOffset, kSize>
+      BodyDescriptorWeak;
+
  private:
   inline bool PretenuringDecisionMade();
 
@@ -5947,6 +5961,8 @@ class Oddball: public HeapObject {
 
   typedef FixedBodyDescriptor<kToStringOffset, kTypeOfOffset + kPointerSize,
                               kSize> BodyDescriptor;
+  // No weak fields.
+  typedef BodyDescriptor BodyDescriptorWeak;
 
   STATIC_ASSERT(kToNumberRawOffset == HeapNumber::kValueOffset);
   STATIC_ASSERT(kKindOffset == Internals::kOddballKindOffset);
@@ -5985,6 +6001,8 @@ class Cell: public HeapObject {
   typedef FixedBodyDescriptor<kValueOffset,
                               kValueOffset + kPointerSize,
                               kSize> BodyDescriptor;
+  // No weak fields.
+  typedef BodyDescriptor BodyDescriptorWeak;
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(Cell);
@@ -6039,6 +6057,8 @@ class PropertyCell : public HeapObject {
   typedef FixedBodyDescriptor<kValueOffset,
                               kSize,
                               kSize> BodyDescriptor;
+  // No weak fields.
+  typedef BodyDescriptor BodyDescriptorWeak;
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(PropertyCell);
@@ -6172,6 +6192,8 @@ class JSProxy: public JSReceiver {
 
   typedef FixedBodyDescriptor<JSReceiver::kPropertiesOffset, kSize, kSize>
       BodyDescriptor;
+  // No weak fields.
+  typedef BodyDescriptor BodyDescriptorWeak;
 
   static Object* GetIdentityHash(Handle<JSProxy> receiver);
 
@@ -6340,17 +6362,17 @@ class JSWeakCollection: public JSObject {
 
   // Visiting policy defines whether the table and next collection fields
   // should be visited or not.
-  enum BodyVisitingPolicy { kVisitStrong, kVisitWeak };
+  enum BodyVisitingPolicy { kIgnoreWeakness, kRespectWeakness };
 
   // Iterates the function object according to the visiting policy.
   template <BodyVisitingPolicy>
   class BodyDescriptorImpl;
 
   // Visit the whole object.
-  typedef BodyDescriptorImpl<kVisitStrong> BodyDescriptor;
+  typedef BodyDescriptorImpl<kIgnoreWeakness> BodyDescriptor;
 
   // Don't visit table and next collection fields.
-  typedef BodyDescriptorImpl<kVisitWeak> BodyDescriptorWeak;
+  typedef BodyDescriptorImpl<kRespectWeakness> BodyDescriptorWeak;
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(JSWeakCollection);
@@ -6482,6 +6504,8 @@ class JSArrayBuffer: public JSObject {
   // Iterates all fields in the object including internal ones except
   // kBackingStoreOffset and kBitFieldSlot.
   class BodyDescriptor;
+  // No weak fields.
+  typedef BodyDescriptor BodyDescriptorWeak;
 
   class IsExternal : public BitField<bool, 1, 1> {};
   class IsNeuterable : public BitField<bool, 2, 1> {};
@@ -6619,6 +6643,8 @@ class Foreign: public HeapObject {
   STATIC_ASSERT(kForeignAddressOffset == Internals::kForeignAddressOffset);
 
   class BodyDescriptor;
+  // No weak fields.
+  typedef BodyDescriptor BodyDescriptorWeak;
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(Foreign);

src/objects/hash-table.h

@@ -653,6 +653,8 @@ class SmallOrderedHashTable : public HeapObject {
 
   // Iterates only fields in the DataTable.
   class BodyDescriptor;
+  // No weak fields.
+  typedef BodyDescriptor BodyDescriptorWeak;
 
   // Returns an SmallOrderedHashTable (possibly |table|) with enough
   // space to add at least one new element.

src/objects/name.h

@@ -161,6 +161,8 @@ class Symbol : public Name {
   static const int kPublicBit = 2;
 
   typedef FixedBodyDescriptor<kNameOffset, kFlagsOffset, kSize> BodyDescriptor;
+  // No weak fields.
+  typedef BodyDescriptor BodyDescriptorWeak;
 
   void SymbolShortPrint(std::ostream& os);
 

src/objects/shared-function-info.h

@@ -468,8 +468,8 @@ class SharedFunctionInfo : public HeapObject {
 
   typedef FixedBodyDescriptor<kCodeOffset, kEndOfPointerFieldsOffset, kSize>
       BodyDescriptor;
-  typedef FixedBodyDescriptor<kNameOffset, kEndOfPointerFieldsOffset, kSize>
-      BodyDescriptorWeakCode;
+  // No weak fields.
+  typedef BodyDescriptor BodyDescriptorWeak;
 
 // Bit fields in |start_position_and_type|.
 #define START_POSITION_AND_TYPE_BIT_FIELDS(V, _) \

src/objects/string.h

@@ -505,6 +505,8 @@ class SeqOneByteString : public SeqString {
   STATIC_ASSERT((kMaxSize - kHeaderSize) >= String::kMaxLength);
 
   class BodyDescriptor;
+  // No weak fields.
+  typedef BodyDescriptor BodyDescriptorWeak;
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(SeqOneByteString);
@@ -546,6 +548,8 @@ class SeqTwoByteString : public SeqString {
                 String::kMaxLength);
 
   class BodyDescriptor;
+  // No weak fields.
+  typedef BodyDescriptor BodyDescriptorWeak;
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(SeqTwoByteString);
@@ -592,6 +596,8 @@ class ConsString : public String {
 
   typedef FixedBodyDescriptor<kFirstOffset, kSecondOffset + kPointerSize, kSize>
       BodyDescriptor;
+  // No weak fields.
+  typedef BodyDescriptor BodyDescriptorWeak;
 
   DECLARE_VERIFIER(ConsString)
 
@@ -623,6 +629,8 @@ class ThinString : public String {
   static const int kSize = kActualOffset + kPointerSize;
 
   typedef FixedBodyDescriptor<kActualOffset, kSize, kSize> BodyDescriptor;
+  // No weak fields.
+  typedef BodyDescriptor BodyDescriptorWeak;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(ThinString);
@@ -664,6 +672,8 @@ class SlicedString : public String {
   typedef FixedBodyDescriptor<kParentOffset, kOffsetOffset + kPointerSize,
                               kSize>
       BodyDescriptor;
+  // No weak fields.
+  typedef BodyDescriptor BodyDescriptorWeak;
 
   DECLARE_VERIFIER(SlicedString)
 
@@ -725,6 +735,8 @@ class ExternalOneByteString : public ExternalString {
   DECLARE_CAST(ExternalOneByteString)
 
   class BodyDescriptor;
+  // No weak fields.
+  typedef BodyDescriptor BodyDescriptorWeak;
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(ExternalOneByteString);
@@ -759,6 +771,8 @@ class ExternalTwoByteString : public ExternalString {
   DECLARE_CAST(ExternalTwoByteString)
 
   class BodyDescriptor;
+  // No weak fields.
+  typedef BodyDescriptor BodyDescriptorWeak;
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(ExternalTwoByteString);