[heap] Refactor heap object iteration

src/heap/mark-compact.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/mark-compact.h"
 
 #include "src/base/atomicops.h"
 #include "src/base/bits.h"
 #include "src/base/sys-info.h"
 #include "src/code-stubs.h"
@@ skipping 115 matching lines @@
     }
   }
 }
 
 static void VerifyMarking(NewSpace* space) {
   Address end = space->top();
   // The bottom position is at the start of its page. Allows us to use
   // 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;
     CHECK(limit == end || !page->Contains(end));
     VerifyMarking(space->heap(), page->area_start(), limit);
   }
 }
 
 
 static void VerifyMarking(PagedSpace* space) {
@@ skipping 31 matching lines @@
         CHECK(!MarkCompactCollector::IsOnEvacuationCandidate(object));
       }
     }
   }
 };
 
 
 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);
   }
 }
 
 
 static void VerifyEvacuation(Heap* heap, PagedSpace* space) {
   if (FLAG_use_allocation_folding && (space == heap->old_space())) {
     return;
   }
   for (Page* p : *space) {
     if (p->IsEvacuationCandidate()) continue;
@@ skipping 104 matching lines @@
 #ifdef VERIFY_HEAP
 void MarkCompactCollector::VerifyMarkbitsAreClean(PagedSpace* space) {
   for (Page* p : *space) {
     CHECK(p->markbits()->IsClean());
     CHECK_EQ(0, p->LiveBytes());
   }
 }
 
 
 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());
   }
 }
 
 
 void MarkCompactCollector::VerifyMarkbitsAreClean() {
   VerifyMarkbitsAreClean(heap_->old_space());
   VerifyMarkbitsAreClean(heap_->code_space());
   VerifyMarkbitsAreClean(heap_->map_space());
@@ skipping 1611 matching lines @@
 void MarkCompactCollector::DiscoverGreyObjectsInSpace(PagedSpace* space) {
   for (Page* p : *space) {
     DiscoverGreyObjectsOnPage(p);
     if (marking_deque()->IsFull()) return;
   }
 }
 
 
 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;
   }
 }
 
 
 bool MarkCompactCollector::IsUnmarkedHeapObject(Object** p) {
   Object* o = *p;
   if (!o->IsHeapObject()) return false;
   HeapObject* heap_object = HeapObject::cast(o);
@@ skipping 1046 matching lines @@
   if (map_word.IsForwardingAddress()) {
     return String::cast(map_word.ToForwardingAddress());
   }
 
   return String::cast(*p);
 }
 
 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();
   new_space->ResetAllocationInfo();
 }
 
 class MarkCompactCollector::Evacuator : public Malloced {
  public:
   enum EvacuationMode {
     kObjectsNewToOld,
@@ skipping 765 matching lines @@
       object->IterateBody(map->instance_type(), size, visitor);
     }
   }
 };
 
 void UpdateToSpacePointersInParallel(Heap* heap, base::Semaphore* semaphore) {
   PageParallelJob<ToSpacePointerUpdateJobTraits> job(
       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();
     job.AddPage(page, std::make_pair(start, end));
   }
   PointersUpdatingVisitor visitor;
   int num_tasks = FLAG_parallel_pointer_update ? job.NumberOfPages() : 1;
   job.Run(num_tasks, [&visitor](int i) { return &visitor; });
 }
 
@@ skipping 245 matching lines @@
       // The target is always in old space, we don't have to record the slot in
       // the old-to-new remembered set.
       DCHECK(!heap()->InNewSpace(target));
       RecordRelocSlot(host, &rinfo, target);
     }
   }
 }
 
 }  // namespace internal
 }  // namespace v8