Revert of [heap] Refactor evacuation for young and old gen into visitors....

Revert of [heap] Refactor evacuation for young and old gen into visitors. (patchset #1 id:1 of https://codereview.chromium.org/1493523003/ )

Reason for revert:
Speculative revert for crashing Canary.

Original issue's description:
> Reland of [heap] Refactor evacuation for young and old gen into visitors. (patchset #1 id:1 of https://codereview.chromium.org/1483393002/ )
>
> Reason for revert:
> Reland after fixing the potential root cause of the canary crasher.
>
> Original issue's description:
> > Revert of [heap] Refactor evacuation for young and old gen into visitors. (patchset #5 id:80001 of https://codereview.chromium.org/1470253002/ )
> >
> > Reason for revert:
> > Still investigating bad canary.
> >
> > Original issue's description:
> > > [heap] Refactor evacuation for young and old gen into visitors.
> > >
> > > Create a visitor for evacuating objects for young and old generation. This is
> > > the first step of preparing a task to process, both,  newspace and oldspace
> > > pages in parallel.
> > >
> > > BUG=chromium:524425
> > > LOG=N
> > >
> > > Committed: https://crrev.com/138d9bae5d7014e0d205634a49b5eac3697744c8
> > > Cr-Commit-Position: refs/heads/master@{#32349}
> >
> > TBR=mlippautz@chromium.org
> > NOPRESUBMIT=true
> > NOTREECHECKS=true
> > NOTRY=true
> > BUG=chromium:524425
> >
> > Committed: https://crrev.com/aa24a3135ec308e1f84bce334844caf0cae2437a
> > Cr-Commit-Position: refs/heads/master@{#32462}
>
> TBR=mlippautz@chromium.org
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=chromium:524425
>
> Committed: https://crrev.com/120b640dfce5f02cecc5af72ca0b2b3b93ce8652
> Cr-Commit-Position: refs/heads/master@{#32500}

TBR=hpayer@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=chromium:524425

Review URL: https://codereview.chromium.org/1495583002

Cr-Commit-Position: refs/heads/master@{#32522}

src/heap/mark-compact.cc

@@ -236,11 +236,6 @@ static void VerifyEvacuation(Heap* heap) {
 
 
 void MarkCompactCollector::SetUp() {
-  DCHECK(strcmp(Marking::kWhiteBitPattern, "00") == 0);
-  DCHECK(strcmp(Marking::kBlackBitPattern, "10") == 0);
-  DCHECK(strcmp(Marking::kGreyBitPattern, "11") == 0);
-  DCHECK(strcmp(Marking::kImpossibleBitPattern, "01") == 0);
-
   free_list_old_space_.Reset(new FreeList(heap_->old_space()));
   free_list_code_space_.Reset(new FreeList(heap_->code_space()));
   free_list_map_space_.Reset(new FreeList(heap_->map_space()));
@@ -1525,119 +1520,69 @@ void MarkCompactCollector::DiscoverGreyObjectsOnPage(MemoryChunk* p) {
 }
 
 
-class MarkCompactCollector::HeapObjectVisitor {
- public:
-  virtual ~HeapObjectVisitor() {}
-  virtual bool Visit(HeapObject* object) = 0;
-};
-
-
-class MarkCompactCollector::EvacuateNewSpaceVisitor
-    : public MarkCompactCollector::HeapObjectVisitor {
- public:
-  explicit EvacuateNewSpaceVisitor(Heap* heap) : heap_(heap) {}
-
-  virtual bool Visit(HeapObject* object) {
-    Heap::UpdateAllocationSiteFeedback(object, Heap::RECORD_SCRATCHPAD_SLOT);
-    int size = object->Size();
-
-    // TODO(hpayer): Refactor EvacuateObject and call this function instead.
-    if (heap_->ShouldBePromoted(object->address(), size) &&
-        heap_->mark_compact_collector()->TryPromoteObject(object, size)) {
-      return true;
-    }
-
-    AllocationAlignment alignment = object->RequiredAlignment();
-    AllocationResult allocation =
-        heap_->new_space()->AllocateRaw(size, alignment);
-    if (allocation.IsRetry()) {
-      if (!heap_->new_space()->AddFreshPage()) {
-        // Shouldn't happen. We are sweeping linearly, and to-space
-        // has the same number of pages as from-space, so there is
-        // always room unless we are in an OOM situation.
-        FatalProcessOutOfMemory("MarkCompactCollector: semi-space copy\n");
-      }
-      allocation = heap_->new_space()->AllocateRaw(size, alignment);
-      DCHECK(!allocation.IsRetry());
-    }
-    Object* target = allocation.ToObjectChecked();
-
-    heap_->mark_compact_collector()->MigrateObject(
-        HeapObject::cast(target), object, size, NEW_SPACE, nullptr);
-    if (V8_UNLIKELY(target->IsJSArrayBuffer())) {
-      heap_->array_buffer_tracker()->MarkLive(JSArrayBuffer::cast(target));
-    }
-    heap_->IncrementSemiSpaceCopiedObjectSize(size);
-    return true;
-  }
+int MarkCompactCollector::DiscoverAndEvacuateBlackObjectsOnPage(
+    NewSpace* new_space, NewSpacePage* p) {
+  DCHECK(strcmp(Marking::kWhiteBitPattern, "00") == 0);
+  DCHECK(strcmp(Marking::kBlackBitPattern, "10") == 0);
+  DCHECK(strcmp(Marking::kGreyBitPattern, "11") == 0);
+  DCHECK(strcmp(Marking::kImpossibleBitPattern, "01") == 0);
 
- private:
-  Heap* heap_;
-};
+  MarkBit::CellType* cells = p->markbits()->cells();
+  int survivors_size = 0;
 
+  for (MarkBitCellIterator it(p); !it.Done(); it.Advance()) {
+    Address cell_base = it.CurrentCellBase();
+    MarkBit::CellType* cell = it.CurrentCell();
 
-class MarkCompactCollector::EvacuateOldSpaceVisitor
-    : public MarkCompactCollector::HeapObjectVisitor {
- public:
-  EvacuateOldSpaceVisitor(Heap* heap,
-                          CompactionSpaceCollection* compaction_spaces,
-                          SlotsBuffer** evacuation_slots_buffer)
-      : heap_(heap),
-        compaction_spaces_(compaction_spaces),
-        evacuation_slots_buffer_(evacuation_slots_buffer) {}
+    MarkBit::CellType current_cell = *cell;
+    if (current_cell == 0) continue;
 
-  virtual bool Visit(HeapObject* object) {
-    int size = object->Size();
-    AllocationAlignment alignment = object->RequiredAlignment();
-    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;
-    }
-    heap_->mark_compact_collector()->MigrateObject(
-        target_object, object, size, id, evacuation_slots_buffer_);
-    DCHECK(object->map_word().IsForwardingAddress());
-    return true;
-  }
+    int offset = 0;
+    while (current_cell != 0) {
+      int trailing_zeros = base::bits::CountTrailingZeros32(current_cell);
+      current_cell >>= trailing_zeros;
+      offset += trailing_zeros;
+      Address address = cell_base + offset * kPointerSize;
+      HeapObject* object = HeapObject::FromAddress(address);
+      DCHECK(Marking::IsBlack(Marking::MarkBitFrom(object)));
 
- private:
-  Heap* heap_;
-  CompactionSpaceCollection* compaction_spaces_;
-  SlotsBuffer** evacuation_slots_buffer_;
-};
+      int size = object->Size();
+      survivors_size += size;
 
+      Heap::UpdateAllocationSiteFeedback(object, Heap::RECORD_SCRATCHPAD_SLOT);
 
-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();
+      offset += 2;
+      current_cell >>= 2;
 
-    if (*cell == 0) continue;
+      // TODO(hpayer): Refactor EvacuateObject and call this function instead.
+      if (heap()->ShouldBePromoted(object->address(), size) &&
+          TryPromoteObject(object, size)) {
+        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]));
+      AllocationAlignment alignment = object->RequiredAlignment();
+      AllocationResult allocation = new_space->AllocateRaw(size, alignment);
+      if (allocation.IsRetry()) {
+        if (!new_space->AddFreshPage()) {
+          // Shouldn't happen. We are sweeping linearly, and to-space
+          // has the same number of pages as from-space, so there is
+          // always room unless we are in an OOM situation.
+          FatalProcessOutOfMemory("MarkCompactCollector: semi-space copy\n");
         }
-        return false;
+        allocation = new_space->AllocateRaw(size, alignment);
+        DCHECK(!allocation.IsRetry());
       }
+      Object* target = allocation.ToObjectChecked();
+
+      MigrateObject(HeapObject::cast(target), object, size, NEW_SPACE, nullptr);
+      if (V8_UNLIKELY(target->IsJSArrayBuffer())) {
+        heap()->array_buffer_tracker()->MarkLive(JSArrayBuffer::cast(target));
+      }
+      heap()->IncrementSemiSpaceCopiedObjectSize(size);
     }
-    if (mode == kClearMarkbits) {
-      *cell = 0;
-    }
+    *cells = 0;
   }
-  return true;
+  return survivors_size;
 }
 
 
@@ -3160,13 +3105,9 @@ 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());
   while (it.has_next()) {
     NewSpacePage* p = it.next();
-    survivors_size += p->LiveBytes();
-    bool ok = IterateLiveObjectsOnPage(p, &new_space_visitor, kClearMarkbits);
-    USE(ok);
-    DCHECK(ok);
+    survivors_size += DiscoverAndEvacuateBlackObjectsOnPage(new_space, p);
   }
 
   heap_->IncrementYoungSurvivorsCounter(survivors_size);
@@ -3181,6 +3122,50 @@ void MarkCompactCollector::AddEvacuationSlotsBufferSynchronized(
 }
 
 
+bool MarkCompactCollector::EvacuateLiveObjectsFromPage(
+    Page* p, PagedSpace* target_space, SlotsBuffer** evacuation_slots_buffer) {
+  AlwaysAllocateScope always_allocate(isolate());
+  DCHECK(p->IsEvacuationCandidate() && !p->WasSwept());
+
+  Address starts[16];
+  for (MarkBitCellIterator it(p); !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, starts);
+    for (int i = 0; i < live_objects; i++) {
+      HeapObject* object = HeapObject::FromAddress(starts[i]);
+      DCHECK(Marking::IsBlack(Marking::MarkBitFrom(object)));
+
+      int size = object->Size();
+      AllocationAlignment alignment = object->RequiredAlignment();
+      HeapObject* target_object = nullptr;
+      AllocationResult allocation = target_space->AllocateRaw(size, alignment);
+      if (!allocation.To(&target_object)) {
+        // We need to abort compaction for this page. Make sure that we reset
+        // the mark bits for objects that have already been migrated.
+        if (i > 0) {
+          p->markbits()->ClearRange(p->AddressToMarkbitIndex(p->area_start()),
+                                    p->AddressToMarkbitIndex(starts[i]));
+        }
+        return false;
+      }
+
+      MigrateObject(target_object, object, size, target_space->identity(),
+                    evacuation_slots_buffer);
+      DCHECK(object->map_word().IsForwardingAddress());
+    }
+
+    // Clear marking bits for current cell.
+    *cell = 0;
+  }
+  p->ResetLiveBytes();
+  return true;
+}
+
+
 int MarkCompactCollector::NumberOfParallelCompactionTasks() {
   if (!FLAG_parallel_compaction) return 1;
   // Compute the number of needed tasks based on a target compaction time, the
@@ -3345,8 +3330,6 @@ void MarkCompactCollector::WaitUntilCompactionCompleted(uint32_t* task_ids,
 void MarkCompactCollector::EvacuatePages(
     CompactionSpaceCollection* compaction_spaces,
     SlotsBuffer** evacuation_slots_buffer) {
-  EvacuateOldSpaceVisitor visitor(heap(), compaction_spaces,
-                                  evacuation_slots_buffer);
   for (int i = 0; i < evacuation_candidates_.length(); i++) {
     Page* p = evacuation_candidates_[i];
     DCHECK(p->IsEvacuationCandidate() ||
@@ -3360,8 +3343,9 @@ void MarkCompactCollector::EvacuatePages(
                   MemoryChunk::kCompactingInProgress);
         double start = heap()->MonotonicallyIncreasingTimeInMs();
         intptr_t live_bytes = p->LiveBytes();
-        if (IterateLiveObjectsOnPage(p, &visitor, kClearMarkbits)) {
-          p->ResetLiveBytes();
+        if (EvacuateLiveObjectsFromPage(
+                p, compaction_spaces->Get(p->owner()->identity()),
+                evacuation_slots_buffer)) {
           p->parallel_compaction_state().SetValue(
               MemoryChunk::kCompactingFinalize);
           compaction_spaces->ReportCompactionProgress(

src/heap/mark-compact.h

@@ -314,15 +314,6 @@ class ThreadLocalTop;
 // Mark-Compact collector
 class MarkCompactCollector {
  public:
-  enum IterationMode {
-    kKeepMarking,
-    kClearMarkbits,
-  };
-
-  class EvacuateNewSpaceVisitor;
-  class EvacuateOldSpaceVisitor;
-  class HeapObjectVisitor;
-
   static void Initialize();
 
   void SetUp();
@@ -701,13 +692,14 @@ class MarkCompactCollector {
   // regions to each space's free list.
   void SweepSpaces();
 
-  // Iterates through all live objects on a page using marking information.
-  // Returns whether all objects have successfully been visited.
-  bool IterateLiveObjectsOnPage(MemoryChunk* page, HeapObjectVisitor* visitor,
-                                IterationMode mode);
+  int DiscoverAndEvacuateBlackObjectsOnPage(NewSpace* new_space,
+                                            NewSpacePage* p);
 
   void EvacuateNewSpace();
 
+  bool EvacuateLiveObjectsFromPage(Page* p, PagedSpace* target_space,
+                                   SlotsBuffer** evacuation_slots_buffer);
+
   void AddEvacuationSlotsBufferSynchronized(
       SlotsBuffer* evacuation_slots_buffer);