Reland "[heap] Unify evacuating an object for new and old generation."

src/heap/mark-compact.cc

Index: src/heap/mark-compact.cc
diff --git a/src/heap/mark-compact.cc b/src/heap/mark-compact.cc
index 42cb71e8e182f30913ebff21b44ab84a601f47bd..c66cd0c13ac7607bc2939c29b931bb0aeca7708a 100644
--- a/src/heap/mark-compact.cc
+++ b/src/heap/mark-compact.cc
@@ -1533,18 +1533,51 @@ class MarkCompactCollector::HeapObjectVisitor {
 };
 
 
-class MarkCompactCollector::EvacuateNewSpaceVisitor
+class MarkCompactCollector::EvacuateVisitorBase
     : public MarkCompactCollector::HeapObjectVisitor {
  public:
-  explicit EvacuateNewSpaceVisitor(Heap* heap) : heap_(heap) {}
+  EvacuateVisitorBase(Heap* heap, SlotsBuffer** evacuation_slots_buffer)
+      : heap_(heap), evacuation_slots_buffer_(evacuation_slots_buffer) {}
 
-  virtual bool Visit(HeapObject* object) {
-    Heap::UpdateAllocationSiteFeedback(object, Heap::RECORD_SCRATCHPAD_SLOT);
+  bool TryEvacuateObject(PagedSpace* target_space, HeapObject* object,
+                         HeapObject** target_object) {
     int size = object->Size();
+    AllocationAlignment alignment = object->RequiredAlignment();
+    AllocationResult allocation = target_space->AllocateRaw(size, alignment);
+    if (allocation.To(target_object)) {
+      heap_->mark_compact_collector()->MigrateObject(
+          *target_object, object, size, target_space->identity(),
+          evacuation_slots_buffer_);
+      return true;
+    }
+    return false;
+  }
 
-    // TODO(hpayer): Refactor EvacuateObject and call this function instead.
+ protected:
+  Heap* heap_;
+  SlotsBuffer** evacuation_slots_buffer_;
+};
+
+
+class MarkCompactCollector::EvacuateNewSpaceVisitor
+    : public MarkCompactCollector::EvacuateVisitorBase {
+ public:
+  explicit EvacuateNewSpaceVisitor(Heap* heap,
+                                   SlotsBuffer** evacuation_slots_buffer)
+      : EvacuateVisitorBase(heap, evacuation_slots_buffer) {}
+
+  bool Visit(HeapObject* object) override {
+    Heap::UpdateAllocationSiteFeedback(object, Heap::RECORD_SCRATCHPAD_SLOT);
+    int size = object->Size();
+    HeapObject* target_object = nullptr;
     if (heap_->ShouldBePromoted(object->address(), size) &&
-        heap_->mark_compact_collector()->TryPromoteObject(object, size)) {
+        TryEvacuateObject(heap_->old_space(), object, &target_object)) {
+      // If we end up needing more special cases, we should factor this out.
+      if (V8_UNLIKELY(target_object->IsJSArrayBuffer())) {
+        heap_->array_buffer_tracker()->Promote(
+            JSArrayBuffer::cast(target_object));
+      }
+      heap_->IncrementPromotedObjectsSize(size);
       return true;
     }
 
@@ -1571,77 +1604,34 @@ class MarkCompactCollector::EvacuateNewSpaceVisitor
     heap_->IncrementSemiSpaceCopiedObjectSize(size);
     return true;
   }
-
- private:
-  Heap* heap_;
 };
 
 
 class MarkCompactCollector::EvacuateOldSpaceVisitor
-    : public MarkCompactCollector::HeapObjectVisitor {
+    : public MarkCompactCollector::EvacuateVisitorBase {
  public:
   EvacuateOldSpaceVisitor(Heap* heap,
                           CompactionSpaceCollection* compaction_spaces,
                           SlotsBuffer** evacuation_slots_buffer)
-      : heap_(heap),
-        compaction_spaces_(compaction_spaces),
-        evacuation_slots_buffer_(evacuation_slots_buffer) {}
+      : EvacuateVisitorBase(heap, evacuation_slots_buffer),
+        compaction_spaces_(compaction_spaces) {}
 
-  virtual bool Visit(HeapObject* object) {
-    int size = object->Size();
-    AllocationAlignment alignment = object->RequiredAlignment();
+  bool Visit(HeapObject* object) override {
+    CompactionSpace* target_space = compaction_spaces_->Get(
+        Page::FromAddress(object->address())->owner()->identity());
     HeapObject* target_object = nullptr;
-    AllocationSpace id =
-        Page::FromAddress(object->address())->owner()->identity();
-    AllocationResult allocation =
-        compaction_spaces_->Get(id)->AllocateRaw(size, alignment);
-    if (!allocation.To(&target_object)) {
-      return false;
+    if (TryEvacuateObject(target_space, object, &target_object)) {
+      DCHECK(object->map_word().IsForwardingAddress());
+      return true;
     }
-    heap_->mark_compact_collector()->MigrateObject(
-        target_object, object, size, id, evacuation_slots_buffer_);
-    DCHECK(object->map_word().IsForwardingAddress());
-    return true;
+    return false;
   }
 
  private:
-  Heap* heap_;
   CompactionSpaceCollection* compaction_spaces_;
-  SlotsBuffer** evacuation_slots_buffer_;
 };
 
 
-bool MarkCompactCollector::IterateLiveObjectsOnPage(MemoryChunk* page,
-                                                    HeapObjectVisitor* visitor,
-                                                    IterationMode mode) {
-  Address offsets[16];
-  for (MarkBitCellIterator it(page); !it.Done(); it.Advance()) {
-    Address cell_base = it.CurrentCellBase();
-    MarkBit::CellType* cell = it.CurrentCell();
-
-    if (*cell == 0) continue;
-
-    int live_objects = MarkWordToObjectStarts(*cell, cell_base, offsets);
-    for (int i = 0; i < live_objects; i++) {
-      HeapObject* object = HeapObject::FromAddress(offsets[i]);
-      DCHECK(Marking::IsBlack(Marking::MarkBitFrom(object)));
-      if (!visitor->Visit(object)) {
-        if ((mode == kClearMarkbits) && (i > 0)) {
-          page->markbits()->ClearRange(
-              page->AddressToMarkbitIndex(page->area_start()),
-              page->AddressToMarkbitIndex(offsets[i]));
-        }
-        return false;
-      }
-    }
-    if (mode == kClearMarkbits) {
-      *cell = 0;
-    }
-  }
-  return true;
-}
-
-
 void MarkCompactCollector::DiscoverGreyObjectsInSpace(PagedSpace* space) {
   PageIterator it(space);
   while (it.has_next()) {
@@ -2994,28 +2984,6 @@ static String* UpdateReferenceInExternalStringTableEntry(Heap* heap,
 }
 
 
-bool MarkCompactCollector::TryPromoteObject(HeapObject* object,
-                                            int object_size) {
-  OldSpace* old_space = heap()->old_space();
-
-  HeapObject* target = nullptr;
-  AllocationAlignment alignment = object->RequiredAlignment();
-  AllocationResult allocation = old_space->AllocateRaw(object_size, alignment);
-  if (allocation.To(&target)) {
-    MigrateObject(target, object, object_size, old_space->identity(),
-                  &migration_slots_buffer_);
-    // If we end up needing more special cases, we should factor this out.
-    if (V8_UNLIKELY(target->IsJSArrayBuffer())) {
-      heap()->array_buffer_tracker()->Promote(JSArrayBuffer::cast(target));
-    }
-    heap()->IncrementPromotedObjectsSize(object_size);
-    return true;
-  }
-
-  return false;
-}
-
-
 bool MarkCompactCollector::IsSlotInBlackObject(Page* p, Address slot,
                                                HeapObject** out_object) {
   Space* owner = p->owner();
@@ -3188,11 +3156,11 @@ void MarkCompactCollector::EvacuateNewSpace() {
   // new entries in the store buffer and may cause some pages to be marked
   // scan-on-scavenge.
   NewSpacePageIterator it(from_bottom, from_top);
-  EvacuateNewSpaceVisitor new_space_visitor(heap());
+  EvacuateNewSpaceVisitor new_space_visitor(heap(), &migration_slots_buffer_);
   while (it.has_next()) {
     NewSpacePage* p = it.next();
     survivors_size += p->LiveBytes();
-    bool ok = IterateLiveObjectsOnPage(p, &new_space_visitor, kClearMarkbits);
+    bool ok = VisitLiveObjects(p, &new_space_visitor, kClearMarkbits);
     USE(ok);
     DCHECK(ok);
   }
@@ -3394,7 +3362,7 @@ void MarkCompactCollector::EvacuatePages(
         double start = heap()->MonotonicallyIncreasingTimeInMs();
         intptr_t live_bytes = p->LiveBytes();
         AlwaysAllocateScope always_allocate(isolate());
-        if (IterateLiveObjectsOnPage(p, &visitor, kClearMarkbits)) {
+        if (VisitLiveObjects(p, &visitor, kClearMarkbits)) {
           p->ResetLiveBytes();
           p->parallel_compaction_state().SetValue(
               MemoryChunk::kCompactingFinalize);
@@ -3581,9 +3549,37 @@ void MarkCompactCollector::RemoveObjectSlots(Address start_slot,
 }
 
 
-void MarkCompactCollector::VisitLiveObjects(Page* page,
-                                            ObjectVisitor* visitor) {
-  // First pass on aborted pages.
+bool MarkCompactCollector::VisitLiveObjects(MemoryChunk* page,
+                                            HeapObjectVisitor* visitor,
+                                            IterationMode mode) {
+  Address offsets[16];
+  for (MarkBitCellIterator it(page); !it.Done(); it.Advance()) {
+    Address cell_base = it.CurrentCellBase();
+    MarkBit::CellType* cell = it.CurrentCell();
+    if (*cell == 0) continue;
+    int live_objects = MarkWordToObjectStarts(*cell, cell_base, offsets);
+    for (int i = 0; i < live_objects; i++) {
+      HeapObject* object = HeapObject::FromAddress(offsets[i]);
+      DCHECK(Marking::IsBlack(Marking::MarkBitFrom(object)));
+      if (!visitor->Visit(object)) {
+        if ((mode == kClearMarkbits) && (i > 0)) {
+          page->markbits()->ClearRange(
+              page->AddressToMarkbitIndex(page->area_start()),
+              page->AddressToMarkbitIndex(offsets[i]));
+        }
+        return false;
+      }
+    }
+    if (mode == kClearMarkbits) {
+      *cell = 0;
+    }
+  }
+  return true;
+}
+
+
+void MarkCompactCollector::VisitLiveObjectsBody(Page* page,
+                                                ObjectVisitor* visitor) {
   Address starts[16];
   for (MarkBitCellIterator it(page); !it.Done(); it.Advance()) {
     Address cell_base = it.CurrentCellBase();
@@ -3728,7 +3724,7 @@ void MarkCompactCollector::EvacuateNewSpaceAndCandidates() {
         // First pass on aborted pages, fixing up all live objects.
         if (p->IsFlagSet(Page::COMPACTION_WAS_ABORTED)) {
           p->ClearEvacuationCandidate();
-          VisitLiveObjects(p, &updating_visitor);
+          VisitLiveObjectsBody(p, &updating_visitor);
         }
       }