Avoid manual object's body traversal in GC.

src/heap/heap.cc

 // 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.
 
 #include "src/heap/heap.h"
 
 #include "src/accessors.h"
 #include "src/api.h"
 #include "src/base/bits.h"
 #include "src/base/once.h"
@@ skipping 4462 matching lines @@
       } else if (record_slots &&
                  MarkCompactCollector::IsOnEvacuationCandidate(target)) {
         mark_compact_collector()->RecordSlot(object, slot, target);
       }
     }
     slot_address += kPointerSize;
   }
 }
 
 
+class IteratePointersToFromSpaceVisitor final : public ObjectVisitor {
+ public:
+  IteratePointersToFromSpaceVisitor(Heap* heap, HeapObject* target,
+                                    bool record_slots,
+                                    ObjectSlotCallback callback)
+      : heap_(heap),
+        target_(target),
+        record_slots_(record_slots),
+        callback_(callback) {}
+
+  V8_INLINE void VisitPointers(Object** start, Object** end) override {
+    heap_->IterateAndMarkPointersToFromSpace(
+        target_, reinterpret_cast<Address>(start),
+        reinterpret_cast<Address>(end), record_slots_, callback_);
+  }
+
+  V8_INLINE void VisitCodeEntry(Address code_entry_slot) override {}
+
+ private:
+  Heap* heap_;
+  HeapObject* target_;
+  bool record_slots_;
+  ObjectSlotCallback callback_;
+};
+
+
 void Heap::IteratePointersToFromSpace(HeapObject* target, int size,
                                       ObjectSlotCallback callback) {
-  Address obj_address = target->address();
-
   // We are not collecting slots on new space objects during mutation
   // thus we have to scan for pointers to evacuation candidates when we
   // promote objects. But we should not record any slots in non-black
   // objects. Grey object's slots would be rescanned.
   // White object might not survive until the end of collection
   // it would be a violation of the invariant to record it's slots.
   bool record_slots = false;
   if (incremental_marking()->IsCompacting()) {
     MarkBit mark_bit = Marking::MarkBitFrom(target);
     record_slots = Marking::IsBlack(mark_bit);
   }
 
-  // Do not scavenge JSArrayBuffer's contents
-  switch (target->ContentType()) {
-    case HeapObjectContents::kTaggedValues: {
-      IterateAndMarkPointersToFromSpace(target, obj_address, obj_address + size,
-                                        record_slots, callback);
-      break;
-    }
-    case HeapObjectContents::kMixedValues: {
-      if (target->IsFixedTypedArrayBase()) {
-        IterateAndMarkPointersToFromSpace(
-            target, obj_address + FixedTypedArrayBase::kBasePointerOffset,
-            obj_address + FixedTypedArrayBase::kHeaderSize, record_slots,
-            callback);
-      } else if (target->IsBytecodeArray()) {
-        IterateAndMarkPointersToFromSpace(
-            target, obj_address + BytecodeArray::kConstantPoolOffset,
-            obj_address + BytecodeArray::kHeaderSize, record_slots, callback);
-      } else if (target->IsJSArrayBuffer()) {
-        IterateAndMarkPointersToFromSpace(
-            target, obj_address,
-            obj_address + JSArrayBuffer::kByteLengthOffset + kPointerSize,
-            record_slots, callback);
-        IterateAndMarkPointersToFromSpace(
-            target, obj_address + JSArrayBuffer::kSize, obj_address + size,
-            record_slots, callback);
-#if V8_DOUBLE_FIELDS_UNBOXING
-      } else if (FLAG_unbox_double_fields) {
-        LayoutDescriptorHelper helper(target->map());
-        DCHECK(!helper.all_fields_tagged());
-
-        for (int offset = 0; offset < size;) {
-          int end_of_region_offset;
-          if (helper.IsTagged(offset, size, &end_of_region_offset)) {
-            IterateAndMarkPointersToFromSpace(
-                target, obj_address + offset,
-                obj_address + end_of_region_offset, record_slots, callback);
-          }
-          offset = end_of_region_offset;
-        }
-#endif
-      }
-      break;
-    }
-    case HeapObjectContents::kRawValues: {
-      break;
-    }
-  }
+  IteratePointersToFromSpaceVisitor visitor(this, target, record_slots,
+                                            callback);
+  target->IterateBody(target->map()->instance_type(), size, &visitor);
 }
 
 
 void Heap::IterateRoots(ObjectVisitor* v, VisitMode mode) {
   IterateStrongRoots(v, mode);
   IterateWeakRoots(v, mode);
 }
 
 
 void Heap::IterateWeakRoots(ObjectVisitor* v, VisitMode mode) {
@@ skipping 1637 matching lines @@
 }
 
 
 // static
 int Heap::GetStaticVisitorIdForMap(Map* map) {
   return StaticVisitorBase::GetVisitorId(map);
 }
 
 }  // namespace internal
 }  // namespace v8