[heap] Refactor heap object iteration

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 8b1c7085c0b2fdf8190b3193b69a6059bd54e223..bad3495bbe4befe1c583ff680b66bc8a845ff213 100644
--- a/src/heap/mark-compact.cc
+++ b/src/heap/mark-compact.cc
@@ -133,7 +133,7 @@ static void VerifyMarking(NewSpace* space) {
   // page->area_start() as start of range on all pages.
   CHECK_EQ(space->bottom(), Page::FromAddress(space->bottom())->area_start());
 
-  NewSpacePageRange range(space->bottom(), end);
+  PageRange range(space->bottom(), end);
   for (auto it = range.begin(); it != range.end();) {
     Page* page = *(it++);
     Address limit = it != range.end() ? page->area_end() : end;
@@ -185,29 +185,21 @@ class VerifyEvacuationVisitor : public ObjectVisitor {
 static void VerifyEvacuation(Page* page) {
   VerifyEvacuationVisitor visitor;
   HeapObjectIterator iterator(page);
-  for (HeapObject* heap_object = iterator.Next(); heap_object != NULL;
+  for (HeapObject* heap_object = iterator.Next(); heap_object != nullptr;
        heap_object = iterator.Next()) {
-    // We skip free space objects.
-    if (!heap_object->IsFiller()) {
-      heap_object->Iterate(&visitor);
-    }
+    CHECK(!heap_object->IsFiller());
+    heap_object->Iterate(&visitor);
   }
 }
 
 
 static void VerifyEvacuation(NewSpace* space) {
   VerifyEvacuationVisitor visitor;
-  NewSpacePageRange range(space->bottom(), space->top());
-  for (auto it = range.begin(); it != range.end();) {
-    Page* page = *(it++);
-    Address current = page->area_start();
-    Address limit = it != range.end() ? page->area_end() : space->top();
-    CHECK(limit == space->top() || !page->Contains(space->top()));
-    while (current < limit) {
-      HeapObject* object = HeapObject::FromAddress(current);
-      object->Iterate(&visitor);
-      current += object->Size();
-    }
+  HeapObjectIterator iterator(space);
+  for (HeapObject* heap_object = iterator.Next(); heap_object != nullptr;
+       heap_object = iterator.Next()) {
+    CHECK(!heap_object->IsFiller());
+    heap_object->Iterate(&visitor);
   }
 }
 
@@ -332,7 +324,7 @@ void MarkCompactCollector::VerifyMarkbitsAreClean(PagedSpace* space) {
 
 
 void MarkCompactCollector::VerifyMarkbitsAreClean(NewSpace* space) {
-  for (Page* p : NewSpacePageRange(space->bottom(), space->top())) {
+  for (Page* p : PageRange(space->bottom(), space->top())) {
     CHECK(p->markbits()->IsClean());
     CHECK_EQ(0, p->LiveBytes());
   }
@@ -1964,7 +1956,7 @@ void MarkCompactCollector::DiscoverGreyObjectsInSpace(PagedSpace* space) {
 
 void MarkCompactCollector::DiscoverGreyObjectsInNewSpace() {
   NewSpace* space = heap()->new_space();
-  for (Page* page : NewSpacePageRange(space->bottom(), space->top())) {
+  for (Page* page : PageRange(space->bottom(), space->top())) {
     DiscoverGreyObjectsOnPage(page);
     if (marking_deque()->IsFull()) return;
   }
@@ -3031,7 +3023,7 @@ static String* UpdateReferenceInExternalStringTableEntry(Heap* heap,
 void MarkCompactCollector::EvacuateNewSpacePrologue() {
   NewSpace* new_space = heap()->new_space();
   // Append the list of new space pages to be processed.
-  for (Page* p : NewSpacePageRange(new_space->bottom(), new_space->top())) {
+  for (Page* p : PageRange(new_space->bottom(), new_space->top())) {
     newspace_evacuation_candidates_.Add(p);
   }
   new_space->Flip();
@@ -3817,7 +3809,7 @@ void UpdateToSpacePointersInParallel(Heap* heap, base::Semaphore* semaphore) {
       heap, heap->isolate()->cancelable_task_manager(), semaphore);
   Address space_start = heap->new_space()->bottom();
   Address space_end = heap->new_space()->top();
-  for (Page* page : NewSpacePageRange(space_start, space_end)) {
+  for (Page* page : PageRange(space_start, space_end)) {
     Address start =
         page->Contains(space_start) ? space_start : page->area_start();
     Address end = page->Contains(space_end) ? space_end : page->area_end();