Fast body iteration for objects without unboxed fields.

src/objects-body-descriptors-inl.h

 // Copyright 2015 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_BODY_DESCRIPTORS_INL_H_
 #define V8_OBJECTS_BODY_DESCRIPTORS_INL_H_
 
 #include "src/assembler-inl.h"
 #include "src/objects-body-descriptors.h"
 #include "src/transitions.h"
 
 namespace v8 {
 namespace internal {
 
 template <int start_offset>
 int FlexibleBodyDescriptor<start_offset>::SizeOf(Map* map, HeapObject* object) {
   return object->SizeFromMap(map);
 }
 
-
 bool BodyDescriptorBase::IsValidSlotImpl(HeapObject* obj, int offset) {
   if (!FLAG_unbox_double_fields || obj->map()->HasFastPointerLayout()) {
     return true;
   } else {
     DCHECK(FLAG_unbox_double_fields);
     DCHECK(IsAligned(offset, kPointerSize));
 
     LayoutDescriptorHelper helper(obj->map());
     DCHECK(!helper.all_fields_tagged());
     return helper.IsTagged(offset);
@@ skipping 15 matching lines @@
     for (int offset = start_offset; offset < end_offset;) {
       int end_of_region_offset;
       if (helper.IsTagged(offset, end_offset, &end_of_region_offset)) {
         IteratePointers(obj, offset, end_of_region_offset, v);
       }
       offset = end_of_region_offset;
     }
   }
 }
 
-
 template <typename StaticVisitor>
 void BodyDescriptorBase::IterateBodyImpl(Heap* heap, HeapObject* obj,
                                          int start_offset, int end_offset) {
   if (!FLAG_unbox_double_fields || obj->map()->HasFastPointerLayout()) {
     IteratePointers<StaticVisitor>(heap, obj, start_offset, end_offset);
   } else {
     DCHECK(FLAG_unbox_double_fields);
     DCHECK(IsAligned(start_offset, kPointerSize) &&
            IsAligned(end_offset, kPointerSize));
 
     LayoutDescriptorHelper helper(obj->map());
     DCHECK(!helper.all_fields_tagged());
     for (int offset = start_offset; offset < end_offset;) {
       int end_of_region_offset;
       if (helper.IsTagged(offset, end_offset, &end_of_region_offset)) {
         IteratePointers<StaticVisitor>(heap, obj, offset, end_of_region_offset);
       }
       offset = end_of_region_offset;
     }
   }
 }
 
-
 template <typename ObjectVisitor>
-DISABLE_CFI_PERF
-void BodyDescriptorBase::IteratePointers(HeapObject* obj, int start_offset,
-                                         int end_offset, ObjectVisitor* v) {
+DISABLE_CFI_PERF void BodyDescriptorBase::IteratePointers(HeapObject* obj,
+                                                          int start_offset,
+                                                          int end_offset,
+                                                          ObjectVisitor* v) {
   v->VisitPointers(HeapObject::RawField(obj, start_offset),
                    HeapObject::RawField(obj, end_offset));
 }
 
-
 template <typename StaticVisitor>
-DISABLE_CFI_PERF
-void BodyDescriptorBase::IteratePointers(Heap* heap, HeapObject* obj,
-                                         int start_offset, int end_offset) {
+DISABLE_CFI_PERF void BodyDescriptorBase::IteratePointers(Heap* heap,
+                                                          HeapObject* obj,
+                                                          int start_offset,
+                                                          int end_offset) {
   StaticVisitor::VisitPointers(heap, obj,
                                HeapObject::RawField(obj, start_offset),
                                HeapObject::RawField(obj, end_offset));
 }
 
-
 template <typename ObjectVisitor>
 void BodyDescriptorBase::IteratePointer(HeapObject* obj, int offset,
                                         ObjectVisitor* v) {
   v->VisitPointer(HeapObject::RawField(obj, offset));
 }
 
-
 template <typename StaticVisitor>
 void BodyDescriptorBase::IteratePointer(Heap* heap, HeapObject* obj,
                                         int offset) {
   StaticVisitor::VisitPointer(heap, obj, HeapObject::RawField(obj, offset));
 }
 
+class JSObject::BodyDescriptor final : public BodyDescriptorBase {
+ public:
+  static const int kStartOffset = JSReceiver::kPropertiesOffset;
+
+  static bool IsValidSlot(HeapObject* obj, int offset) {
+    if (offset < kStartOffset) return false;
+    return IsValidSlotImpl(obj, offset);
+  }
+
+  template <typename ObjectVisitor>
+  static inline void IterateBody(HeapObject* obj, int object_size,
+                                 ObjectVisitor* v) {
+    IterateBodyImpl(obj, kStartOffset, object_size, v);
+  }
+
+  template <typename StaticVisitor>
+  static inline void IterateBody(HeapObject* obj, int object_size) {
+    Heap* heap = obj->GetHeap();
+    IterateBodyImpl<StaticVisitor>(heap, obj, kStartOffset, object_size);
+  }
+
+  static inline int SizeOf(Map* map, HeapObject* object) {
+    return map->instance_size();
+  }
+};
 
 // Iterates the function object according to the visiting policy.
 template <JSFunction::BodyVisitingPolicy body_visiting_policy>
 class JSFunction::BodyDescriptorImpl final : public BodyDescriptorBase {
  public:
   STATIC_ASSERT(kNonWeakFieldsEndOffset == kCodeEntryOffset);
   STATIC_ASSERT(kCodeEntryOffset + kPointerSize == kNextFunctionLinkOffset);
   STATIC_ASSERT(kNextFunctionLinkOffset + kPointerSize == kSize);
 
   static bool IsValidSlot(HeapObject* obj, int offset) {
@@ skipping 31 matching lines @@
       IteratePointers<StaticVisitor>(heap, obj, kNextFunctionLinkOffset, kSize);
     }
     IterateBodyImpl<StaticVisitor>(heap, obj, kSize, object_size);
   }
 
   static inline int SizeOf(Map* map, HeapObject* object) {
     return map->instance_size();
   }
 };
 
-
 class JSArrayBuffer::BodyDescriptor final : public BodyDescriptorBase {
  public:
   STATIC_ASSERT(kByteLengthOffset + kPointerSize == kBackingStoreOffset);
   STATIC_ASSERT(kBackingStoreOffset + kPointerSize == kBitFieldSlot);
   STATIC_ASSERT(kBitFieldSlot + kPointerSize == kSize);
 
   static bool IsValidSlot(HeapObject* obj, int offset) {
     if (offset < kBackingStoreOffset) return true;
     if (offset < kSize) return false;
     return IsValidSlotImpl(obj, offset);
@@ skipping 12 matching lines @@
     IteratePointers<StaticVisitor>(heap, obj, kPropertiesOffset,
                                    kBackingStoreOffset);
     IterateBodyImpl<StaticVisitor>(heap, obj, kSize, object_size);
   }
 
   static inline int SizeOf(Map* map, HeapObject* object) {
     return map->instance_size();
   }
 };
 
-
 class BytecodeArray::BodyDescriptor final : public BodyDescriptorBase {
  public:
   static bool IsValidSlot(HeapObject* obj, int offset) {
     return offset >= kConstantPoolOffset &&
            offset <= kSourcePositionTableOffset;
   }
 
   template <typename ObjectVisitor>
   static inline void IterateBody(HeapObject* obj, int object_size,
                                  ObjectVisitor* v) {
     IteratePointer(obj, kConstantPoolOffset, v);
     IteratePointer(obj, kHandlerTableOffset, v);
     IteratePointer(obj, kSourcePositionTableOffset, v);
   }
 
   template <typename StaticVisitor>
   static inline void IterateBody(HeapObject* obj, int object_size) {
     Heap* heap = obj->GetHeap();
     IteratePointer<StaticVisitor>(heap, obj, kConstantPoolOffset);
     IteratePointer<StaticVisitor>(heap, obj, kHandlerTableOffset);
     IteratePointer<StaticVisitor>(heap, obj, kSourcePositionTableOffset);
   }
 
   static inline int SizeOf(Map* map, HeapObject* obj) {
     return reinterpret_cast<BytecodeArray*>(obj)->BytecodeArraySize();
   }
 };
 
-
 class FixedTypedArrayBase::BodyDescriptor final : public BodyDescriptorBase {
  public:
   static bool IsValidSlot(HeapObject* obj, int offset) {
     return offset == kBasePointerOffset;
   }
 
   template <typename ObjectVisitor>
   static inline void IterateBody(HeapObject* obj, int object_size,
                                  ObjectVisitor* v) {
     IteratePointer(obj, kBasePointerOffset, v);
   }
 
   template <typename StaticVisitor>
   static inline void IterateBody(HeapObject* obj, int object_size) {
     Heap* heap = obj->GetHeap();
     IteratePointer<StaticVisitor>(heap, obj, kBasePointerOffset);
   }
 
   static inline int SizeOf(Map* map, HeapObject* object) {
     return reinterpret_cast<FixedTypedArrayBase*>(object)->size();
   }
 };
 
-
 template <JSWeakCollection::BodyVisitingPolicy body_visiting_policy>
 class JSWeakCollection::BodyDescriptorImpl final : public BodyDescriptorBase {
  public:
   STATIC_ASSERT(kTableOffset + kPointerSize == kNextOffset);
   STATIC_ASSERT(kNextOffset + kPointerSize == kSize);
 
   static bool IsValidSlot(HeapObject* obj, int offset) {
     return IsValidSlotImpl(obj, offset);
   }
 
@@ skipping 18 matching lines @@
                                      kTableOffset);
       IterateBodyImpl<StaticVisitor>(heap, obj, kSize, object_size);
     }
   }
 
   static inline int SizeOf(Map* map, HeapObject* object) {
     return map->instance_size();
   }
 };
 
-
 class Foreign::BodyDescriptor final : public BodyDescriptorBase {
  public:
   static bool IsValidSlot(HeapObject* obj, int offset) { return false; }
 
   template <typename ObjectVisitor>
   static inline void IterateBody(HeapObject* obj, int object_size,
                                  ObjectVisitor* v) {
     v->VisitExternalReference(reinterpret_cast<Address*>(
         HeapObject::RawField(obj, kForeignAddressOffset)));
   }
 
   template <typename StaticVisitor>
   static inline void IterateBody(HeapObject* obj, int object_size) {
     StaticVisitor::VisitExternalReference(reinterpret_cast<Address*>(
         HeapObject::RawField(obj, kForeignAddressOffset)));
   }
 
   static inline int SizeOf(Map* map, HeapObject* object) { return kSize; }
 };
 
-
 class ExternalOneByteString::BodyDescriptor final : public BodyDescriptorBase {
  public:
   static bool IsValidSlot(HeapObject* obj, int offset) { return false; }
 
   template <typename ObjectVisitor>
   static inline void IterateBody(HeapObject* obj, int object_size,
                                  ObjectVisitor* v) {
     typedef v8::String::ExternalOneByteStringResource Resource;
     v->VisitExternalOneByteString(reinterpret_cast<Resource**>(
         HeapObject::RawField(obj, kResourceOffset)));
   }
 
   template <typename StaticVisitor>
   static inline void IterateBody(HeapObject* obj, int object_size) {
     typedef v8::String::ExternalOneByteStringResource Resource;
     StaticVisitor::VisitExternalOneByteString(reinterpret_cast<Resource**>(
         HeapObject::RawField(obj, kResourceOffset)));
   }
 
   static inline int SizeOf(Map* map, HeapObject* object) { return kSize; }
 };
 
-
 class ExternalTwoByteString::BodyDescriptor final : public BodyDescriptorBase {
  public:
   static bool IsValidSlot(HeapObject* obj, int offset) { return false; }
 
   template <typename ObjectVisitor>
   static inline void IterateBody(HeapObject* obj, int object_size,
                                  ObjectVisitor* v) {
     typedef v8::String::ExternalStringResource Resource;
     v->VisitExternalTwoByteString(reinterpret_cast<Resource**>(
         HeapObject::RawField(obj, kResourceOffset)));
   }
 
   template <typename StaticVisitor>
   static inline void IterateBody(HeapObject* obj, int object_size) {
     typedef v8::String::ExternalStringResource Resource;
     StaticVisitor::VisitExternalTwoByteString(reinterpret_cast<Resource**>(
         HeapObject::RawField(obj, kResourceOffset)));
   }
 
   static inline int SizeOf(Map* map, HeapObject* object) { return kSize; }
 };
 
-
 class Code::BodyDescriptor final : public BodyDescriptorBase {
  public:
   STATIC_ASSERT(kRelocationInfoOffset + kPointerSize == kHandlerTableOffset);
   STATIC_ASSERT(kHandlerTableOffset + kPointerSize ==
                 kDeoptimizationDataOffset);
   STATIC_ASSERT(kDeoptimizationDataOffset + kPointerSize ==
                 kSourcePositionTableOffset);
   STATIC_ASSERT(kSourcePositionTableOffset + kPointerSize ==
                 kTypeFeedbackInfoOffset);
   STATIC_ASSERT(kTypeFeedbackInfoOffset + kPointerSize ==
@@ skipping 246 matching lines @@
 
 template <typename ObjectVisitor>
 void HeapObject::IterateBodyFast(InstanceType type, int object_size,
                                  ObjectVisitor* v) {
   BodyDescriptorApply<CallIterateBody, void>(type, this, object_size, v);
 }
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_OBJECTS_BODY_DESCRIPTORS_INL_H_