[heap] Reland "Remove size specializations in static object visitors. (patchset #4 id:60001 of http…

src/heap/objects-visiting.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_OBJECTS_VISITING_H_
 #define V8_OBJECTS_VISITING_H_
 
 #include "src/allocation.h"
 #include "src/heap/embedder-tracing.h"
 #include "src/heap/heap.h"
@@ skipping 23 matching lines @@
   V(ShortcutCandidate)     \
   V(ByteArray)             \
   V(BytecodeArray)         \
   V(FreeSpace)             \
   V(FixedArray)            \
   V(FixedDoubleArray)      \
   V(FixedTypedArray)       \
   V(FixedFloat64Array)     \
   V(NativeContext)         \
   V(AllocationSite)        \
-  V(DataObject2)           \
-  V(DataObject3)           \
-  V(DataObject4)           \
-  V(DataObject5)           \
-  V(DataObject6)           \
-  V(DataObject7)           \
-  V(DataObject8)           \
-  V(DataObject9)           \
-  V(DataObjectGeneric)     \
-  V(JSObject2)             \
-  V(JSObject3)             \
-  V(JSObject4)             \
-  V(JSObject5)             \
-  V(JSObject6)             \
-  V(JSObject7)             \
-  V(JSObject8)             \
-  V(JSObject9)             \
-  V(JSObjectGeneric)       \
-  V(JSApiObject2)          \
-  V(JSApiObject3)          \
-  V(JSApiObject4)          \
-  V(JSApiObject5)          \
-  V(JSApiObject6)          \
-  V(JSApiObject7)          \
-  V(JSApiObject8)          \
-  V(JSApiObject9)          \
-  V(JSApiObjectGeneric)    \
-  V(Struct2)               \
-  V(Struct3)               \
-  V(Struct4)               \
-  V(Struct5)               \
-  V(Struct6)               \
-  V(Struct7)               \
-  V(Struct8)               \
-  V(Struct9)               \
-  V(StructGeneric)         \
+  V(DataObject)            \
+  V(JSObjectFast)          \
+  V(JSObject)              \
+  V(JSApiObject)           \
+  V(Struct)                \
   V(ConsString)            \
   V(SlicedString)          \
   V(ThinString)            \
   V(Symbol)                \
   V(Oddball)               \
   V(Code)                  \
   V(Map)                   \
   V(Cell)                  \
   V(PropertyCell)          \
   V(WeakCell)              \
@@ skipping 10 matching lines @@
   // Ids of specialized visitors are declared in a linear order (without
   // holes) starting from the id of visitor specialized for 2 words objects
   // (base visitor id) and ending with the id of generic visitor.
   // Method GetVisitorIdForSize depends on this ordering to calculate visitor
   // id of specialized visitor from given instance size, base visitor id and
   // generic visitor's id.
   enum VisitorId {
 #define VISITOR_ID_ENUM_DECL(id) kVisit##id,
     VISITOR_ID_LIST(VISITOR_ID_ENUM_DECL)
 #undef VISITOR_ID_ENUM_DECL
-        kVisitorIdCount,
-    kVisitDataObject = kVisitDataObject2,
-    kVisitJSObject = kVisitJSObject2,
-    kVisitJSApiObject = kVisitJSApiObject2,
-    kVisitStruct = kVisitStruct2,
+        kVisitorIdCount
   };
 
   // Visitor ID should fit in one byte.
   STATIC_ASSERT(kVisitorIdCount <= 256);
 
   // Determine which specialized visitor should be used for given instance type
   // and instance type.
   static VisitorId GetVisitorId(int instance_type, int instance_size,
                                 bool has_unboxed_fields);
 
   // Determine which specialized visitor should be used for given map.
   static VisitorId GetVisitorId(Map* map);
-
-  // For visitors that allow specialization by size calculate VisitorId based
-  // on size, base visitor id and generic visitor id.
-  static VisitorId GetVisitorIdForSize(VisitorId base, VisitorId generic,
-                                       int object_size,
-                                       bool has_unboxed_fields) {
-    DCHECK((base == kVisitDataObject) || (base == kVisitStruct) ||
-           (base == kVisitJSObject) || (base == kVisitJSApiObject));
-    DCHECK(IsAligned(object_size, kPointerSize));
-    DCHECK(Heap::kMinObjectSizeInWords * kPointerSize <= object_size);
-    DCHECK(object_size <= kMaxRegularHeapObjectSize);
-    DCHECK(!has_unboxed_fields || (base == kVisitJSObject) ||
-           (base == kVisitJSApiObject));
-
-    if (has_unboxed_fields) return generic;
-
-    int visitor_id = Min(
-        base + (object_size >> kPointerSizeLog2) - Heap::kMinObjectSizeInWords,
-        static_cast<int>(generic));
-
-    return static_cast<VisitorId>(visitor_id);
-  }
 };
 
 
 template <typename Callback>
 class VisitorDispatchTable {
  public:
   void CopyFrom(VisitorDispatchTable* other) {
     // We are not using memcpy to guarantee that during update
     // every element of callbacks_ array will remain correct
     // pointer (memcpy might be implemented as a byte copying loop).
     for (int i = 0; i < StaticVisitorBase::kVisitorIdCount; i++) {
       base::NoBarrier_Store(&callbacks_[i], other->callbacks_[i]);
     }
   }
 
   inline Callback GetVisitor(Map* map);
 
   inline Callback GetVisitorById(StaticVisitorBase::VisitorId id) {
     return reinterpret_cast<Callback>(callbacks_[id]);
   }
 
   void Register(StaticVisitorBase::VisitorId id, Callback callback) {
     DCHECK(id < StaticVisitorBase::kVisitorIdCount);  // id is unsigned.
     callbacks_[id] = reinterpret_cast<base::AtomicWord>(callback);
   }
 
-  template <typename Visitor, StaticVisitorBase::VisitorId base,
-            StaticVisitorBase::VisitorId generic, int object_size_in_words>
-  void RegisterSpecialization() {
-    static const int size = object_size_in_words * kPointerSize;
-    Register(StaticVisitorBase::GetVisitorIdForSize(base, generic, size, false),
-             &Visitor::template VisitSpecialized<size>);
-  }
-
-
-  template <typename Visitor, StaticVisitorBase::VisitorId base,
-            StaticVisitorBase::VisitorId generic>
-  void RegisterSpecializations() {
-    STATIC_ASSERT((generic - base + Heap::kMinObjectSizeInWords) == 10);
-    RegisterSpecialization<Visitor, base, generic, 2>();
-    RegisterSpecialization<Visitor, base, generic, 3>();
-    RegisterSpecialization<Visitor, base, generic, 4>();
-    RegisterSpecialization<Visitor, base, generic, 5>();
-    RegisterSpecialization<Visitor, base, generic, 6>();
-    RegisterSpecialization<Visitor, base, generic, 7>();
-    RegisterSpecialization<Visitor, base, generic, 8>();
-    RegisterSpecialization<Visitor, base, generic, 9>();
-    Register(generic, &Visitor::Visit);
-  }
-
  private:
   base::AtomicWord callbacks_[StaticVisitorBase::kVisitorIdCount];
 };
 
 
 template <typename StaticVisitor, typename BodyDescriptor, typename ReturnType>
 class FlexibleBodyVisitor : public AllStatic {
  public:
   INLINE(static ReturnType Visit(Map* map, HeapObject* object)) {
     int object_size = BodyDescriptor::SizeOf(map, object);
     BodyDescriptor::template IterateBody<StaticVisitor>(object, object_size);
     return static_cast<ReturnType>(object_size);
   }
-
-  // This specialization is only suitable for objects containing pointer fields.
-  template <int object_size>
-  static inline ReturnType VisitSpecialized(Map* map, HeapObject* object) {
-    DCHECK(BodyDescriptor::SizeOf(map, object) == object_size);
-    DCHECK(!FLAG_unbox_double_fields || map->HasFastPointerLayout());
-    StaticVisitor::VisitPointers(
-        object->GetHeap(), object,
-        HeapObject::RawField(object, BodyDescriptor::kStartOffset),
-        HeapObject::RawField(object, object_size));
-    return static_cast<ReturnType>(object_size);
-  }
 };
 
 
 template <typename StaticVisitor, typename BodyDescriptor, typename ReturnType>
 class FixedBodyVisitor : public AllStatic {
  public:
   INLINE(static ReturnType Visit(Map* map, HeapObject* object)) {
     BodyDescriptor::template IterateBody<StaticVisitor>(object);
     return static_cast<ReturnType>(BodyDescriptor::kSize);
   }
@@ skipping 48 matching lines @@
 
   INLINE(static int VisitByteArray(Map* map, HeapObject* object)) {
     return reinterpret_cast<ByteArray*>(object)->ByteArraySize();
   }
 
   INLINE(static int VisitFixedDoubleArray(Map* map, HeapObject* object)) {
     int length = reinterpret_cast<FixedDoubleArray*>(object)->length();
     return FixedDoubleArray::SizeFor(length);
   }
 
-  INLINE(static int VisitJSObject(Map* map, HeapObject* object)) {
-    return JSObjectVisitor::Visit(map, object);
-  }
-
   INLINE(static int VisitSeqOneByteString(Map* map, HeapObject* object)) {
     return SeqOneByteString::cast(object)
         ->SeqOneByteStringSize(map->instance_type());
   }
 
   INLINE(static int VisitSeqTwoByteString(Map* map, HeapObject* object)) {
     return SeqTwoByteString::cast(object)
         ->SeqTwoByteStringSize(map->instance_type());
   }
 
@@ skipping 12 matching lines @@
       return map->instance_size();
     }
   };
 
   typedef FlexibleBodyVisitor<StaticVisitor, StructBodyDescriptor, int>
       StructVisitor;
 
   typedef FlexibleBodyVisitor<StaticVisitor, JSObject::BodyDescriptor, int>
       JSObjectVisitor;
 
+  // Visitor for JSObjects without unboxed double fields.
+  typedef FlexibleBodyVisitor<StaticVisitor, JSObject::FastBodyDescriptor, int>
+      JSObjectFastVisitor;
+
   typedef int (*Callback)(Map* map, HeapObject* object);
 
   static VisitorDispatchTable<Callback> table_;
 };
 
 
 template <typename StaticVisitor>
 VisitorDispatchTable<typename StaticNewSpaceVisitor<StaticVisitor>::Callback>
     StaticNewSpaceVisitor<StaticVisitor>::table_;
 
@@ skipping 63 matching lines @@
    public:
     template <int size>
     static inline void VisitSpecialized(Map* map, HeapObject* object) {}
 
     INLINE(static void Visit(Map* map, HeapObject* object)) {}
   };
 
   typedef FlexibleBodyVisitor<StaticVisitor, FixedArray::BodyDescriptor, void>
       FixedArrayVisitor;
 
+  typedef FlexibleBodyVisitor<StaticVisitor, JSObject::FastBodyDescriptor, void>
+      JSObjectFastVisitor;
   typedef FlexibleBodyVisitor<StaticVisitor, JSObject::BodyDescriptor, void>
       JSObjectVisitor;
 
   class JSApiObjectVisitor : AllStatic {
    public:
-    template <int size>
-    static inline void VisitSpecialized(Map* map, HeapObject* object) {
-      TracePossibleWrapper(object);
-      JSObjectVisitor::template VisitSpecialized<size>(map, object);
-    }
-
     INLINE(static void Visit(Map* map, HeapObject* object)) {
       TracePossibleWrapper(object);
       JSObjectVisitor::Visit(map, object);
     }
 
    private:
     INLINE(static void TracePossibleWrapper(HeapObject* object)) {
       if (object->GetHeap()->local_embedder_heap_tracer()->InUse()) {
         DCHECK(object->IsJSObject());
         object->GetHeap()->TracePossibleWrapper(JSObject::cast(object));
@@ skipping 22 matching lines @@
 // the next element. Given the head of the list, this function removes dead
 // elements from the list and if requested records slots for next-element
 // pointers. The template parameter T is a WeakListVisitor that defines how to
 // access the next-element pointers.
 template <class T>
 Object* VisitWeakList(Heap* heap, Object* list, WeakObjectRetainer* retainer);
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_OBJECTS_VISITING_H_